Memory is a tool on which many people rely heavily every day. How and what is remembered plays a significant role in determining how people act in their daily lives (Araya, Ekehammar & Akrami, 2003). It is important to understand how memory works as a way of understanding more about people in general, and specifically about how the brain stores information. With this information people can be helped to expand and build memory, those with learning disabilities can be treated, and eyewitness testimony can be filtered for accuracy (Dysart, Lindsay, Hammond & Dupuis, 2001). Understanding memory has and will continue to influence many disciplines and help uncover the myriad mysteries of the mind (McNamara & Wong, 2003).

Researchers have spent decades studying the mechanisms of memory (Ho, Cheung, & Chan 2003). There are several different types of memory, such as episodic, which allows people to remember specific events with striking clarity. Implicit memories are pieces of information people know, but are not aware of the source. Conversely, explicit memories are pieces of information people can remember and they can also remember when and how they acquired that information.

Most researchers believe that a piece of knowledge must pass through a series of “gates” before it is permanently stored in memory (Ward & Loftus, 1985). The first of these gates is called working memory, where objects that are being attended to at the present moment are stored. Objects in working memory can remain there anywhere from two seconds to several minutes before either being forgotten or passing though the next gate, known as short term memory.

Short term memory is similar to working memory, and not all researchers agree on the distinction between working memory and short term memory (Hinson, Jameson & Whitney, 2003) However, short term memory is considered to be the staging area where the fate of a piece of information is decided; it will either fail to be encoded as a memory, and so be forgotten, or it will pass into permastore, where long term memories are held. Approximately 7 items can be stored in short term memory at one time.

With this knowledge, researchers have been able to test memory skills under a variety of conditions and in many circumstances, to arrive at a better understanding of memory skills and function. In order to attain this knowledge, most of the research in memory has been aimed at short term or working memory (Hinson, Jameson & Whitney, 2003). For example, researchers know that information to which people are exposed in passing can sometimes remain, subconsciously, in memory and can influence future decisions (Bushman & Bonacci, 2002). This information is frequently used in advertising, where advertisers hope that frequent exposure to their products will prompt more purchases at the store. Extensive market research has shown that consumers are indeed influenced by this exposure (Bushman & Bonacci, 2002).

In the 2003 study by Hinson, Jameson and Whitney, it was found that individual differences in working memory are related to decision making that favors short-term over long-term consequences. People with more efficient working memories were better able to process and weigh the differences between a short-term reward, which appeared better at first glance, and a long-term reward, which was actually the better choice. There were some differences noted in the working memory processes of the individuals who chose the long-term reward.

One of the most popular areas of memory research is that of eyewitness testimony and identification (Dysart, Lindsay, Hammond & Dupuis, 2001). In a study by Dysart and colleagues (2001), there was significant evidence to show that eyewitnesses who had been shown mug shots of suspects prior to participating in a lineup were more likely to choose a suspect to whom they had been previously exposed. The implications of this research are monumental: A suspect can be incarcerated on the basis of testimony that may have inadvertently been planted in memory by the viewing of mug shots. With this research, the lives of many innocent people may be spared.

Another study on eyewitness performance by Ward and Loftus (1985) showed that when two people witness the same event, their memories will be different. They also found that people with certain personality traits were more likely to me misled by false information.

Verbal and visual memory are two more types of memory. Verbal refers to remembering associated with words, like how many words a person can remember when they hear them read aloud. Visual memory refers to the amount and accuracy of recollections having to do with visual stimuli, such as the details of the slide show in the current study. It has been found that verbal memory is affected by interference in working memory (Woodman, Vogel & Luck, 2001). For example, if a person is asked to remember a series of words that are read aloud, and then must complete a task that fills their working memory, they are much less likely to accurately recall the words. Since verbal and visual memory are closely related, logic would assume that the same rule would hold true for visual memory.

To this end, it is hypothesized that the more interference that is present between the stimulus and the desired response, the less accurate the participants’ responses will be. Group 1, which has only a time delay, should have the most accurate responses, and there should be a significant difference between the accuracy of the responses of group 2, which had the easy task interference condition, and group 3, which had the difficult task interference condition.

Method

Participants

Participants were 17 undergraduate students enrolled in the Thursday lab section of experimental psychology at Rutgers University. Group 1, the control group, consisted of 5 students, while groups 2 and 3 consisted of 6 students. Students were randomly assigned to groups as they entered the classroom. Students who participated were given class credit for their participation in this and several other experiments.

Procedure

It should be noted that this study was conducted after a very short study in this same lab period. Participants may have had less interest in this study because they were told it was the longer of the two, or they may have been impatient to leave. Participants were shown a brief slide show of a man visiting several stores, examining merchandise, and shoplifting several items. Group 1, the control group, was then required to sit quietly for 5 minutes, while group 2 completed an easy task and group 3 completed a difficult task. The easy task was to look for pictures of items in a newspaper and to record the page number on which they were found on a questionnaire. The difficult task was to complete the crossword puzzle in the newspaper and writing a brief assessment of one’s puzzle solving abilities.

After the 5 minute period, all participants read a narrative that told the same basic story as the slide show, but with some misleading and some reinforcing statements.

After the narrative, another 5 minute period followed in which group 1 was required to sit quietly, group 2 completed an easy task, and group 3 completed a difficult task. The easy task was again identifying pictures in a newspaper, while the difficult task consisted of answering questions based on information embedded in different newspaper articles.

After the second 5 minute period, all participants were tested on their memory of specific details from the slide show.

Results

The data indicated support for the hypothesis that the group with the most interference between the slide show and the questions would yield the most inaccurate responses. However, group 2 (easy task), out-performed both group 1 (control group), and group 3 (hard task). It appears that when slightly challenged, participants perform at their optimal level.

Group 1 performed better than Group 3, but not as well as Group 2. This may be attributable to the fact that the participants of Group 1 had nothing with which to occupy their minds except their own thoughts, and they may have grown bored and disinterested during the two periods of down time. Group 3 did have the fewest accurate responses, due to the fact that their tasks were the most challenging and required the most abstract thought. These results are in keeping with the hypothesis that, with too much interference, the brain is unable to store a lot of information in working memory. However, the hypothesis did not anticipate that no interference at all may in fact prove more distracting than a small amount of interference.

Though our experiment yielded results which seem to be an accurate demonstration of the capacities of memory, further research is highly suggested. Due to the fact that this lab class has only minimal students and several were absent during the experiment, the results may not be as reliable as possible. Having a large sample group is an important factor for any experiment. Because these experimental groups were so small, it would be advisable to try and re-create these results with a larger, more diverse subject pool.

In the questionnaire regarding the slide show, the questions were classified as reinforced: items in the slide show were mentioned correctly in the narrative (e.g. yellow candle); misled: items in the slide show were mentioned incorrectly in the narrative (e.g. white candle); slide only: items in the slide show were not mentioned in the narrative; and neutral: items in the slide show were mentioned in the slide show, but with no modifiers (e.g. candle). There were four (4) misleading questions, eight (8) slide only questions, four (4) neutral questions, and four (4) reinforced questions.

All groups performed the same or better with reinforced questions than with any other questions. Group 1, the control group, had a 90% overall accuracy for reinforced questions, 87.5% for slide only, 85% for neutral questions, and only 40% for misleading questions. Group 2, the easy task group, had 87.5% overall accuracy for both the reinforced and slide only questions, 79.2% for neutral questions, and 66.7% for misleading questions. Group 3, the hard task group, had 95.8% overall accuracy for reinforced questions, 85. 4% for slide only questions, 70.8% for neutral questions, and only 33.3% for misleading questions. Out of all the groups, group 3 had the best overall accuracy for reinforced questions, and the worst overall accuracy for misleading questions.

Group 2 had the least variance, a 20.8% difference, in their overall accuracy between the misleading and reinforced questions, group 1 had a 40% variance, and group 3 had 62.5%, the most variance.

All 3 groups rated themselves similarly to one another on confidence judgments, and across all categories of questions. Across all 20 questions, Group 2 rated themselves an overall confidence of 87.81%, Group 1 rated themselves an overall confidence of 88.48%, and Group 3 rated themselves an overall confidence of 88.57%. All groups rated their performance within 1% of each other. However, Group 3 (hard task), who yielded the least accurate responses, rated themselves highest in confidence. Group 2, (easy task), who yielded the most accurate responses, rated themselves lowest in confidence, and Group 1 (control group) rated themselves right in the middle.

Group 3 showed an overall accuracy for confidence judgments of 71.35%, Group 1 showed 75.63%, and Group 2 showed 80.21%. Group 2 did nearly 10% better than group 3 and nearly 5% better than group 1.

Conclusion

A most interesting phenomenon lies in the results of the confidence judgments. It appears that participants have no true idea of their actual accuracy in answering questions. Regardless of their actual accuracy, all 3 groups rated themselves fairly high on their confidence levels, and extremely close to one another. These results are in keeping with the findings of Elizabeth Loftus (1986), who demonstrated that individuals’ confidence of their answers has no bearing on their actual results.

It appears that, for working memory to function at an optimal level, some interference or distraction is desirable. When individuals are forced to concentrate too avidly on a task, they appear to lose interest and become easily distracted from their goal. When there is too much interference or distraction, however, the individual is unable to recall all the information from working or short term memory, probably due to the fact that they are forced to channel their concentration almost completely into other areas. Therefore, the data lead to the conclusion that a low level of distraction has the capability of driving the memory to achieve greater results.

It would be interesting to try to replicate these results with a larger group of participants, and also to create more distinction between the difficulties of each group’s task. Doing so may yield more detailed information on the intricacies of working memory.

According to the Flight Safety Foundation, a leading organization dedicated to lowering the risks in aviation, the four most pressing aviation safety issues are Controlled Flight into Terrain (CFIT), Approach and Landing, Loss of Control and Human Factors. Of these four, the top priority for the Flight Safety Foundation is reducing accidents as a result of Controlled Flight into Terrain.

The FAA defines CFIT as occurring “when an airworthy aircraft is flown, under the control of a qualified pilot, into terrain (water or obstacles) with inadequate awareness on the part of the pilot of the impending collision.”[2] CFIT accidents are responsible for more than half of all commercial aviation fatalities during the past 10 years.[3] In General Aviation, CFIT accidents account for seventeen percent of all accidents.[4]

A CFIT accident is the accident category most clearly attributable to human error. In considering the definition, there is a qualified pilot flying a perfectly flyable airplane yet the flight ends in an accident. The definition includes assigning the blame as inadequate awareness on the part of the pilot, in other words, human error.  These types of accidents occur either because the pilot is laterally displaced from the intended position or the pilot is lower than intended, sometimes both.

Most aviation accidents can be traced back to a human error but CFIT accidents are particularly troubling due to the percentage of fatalities as a result of the accident.    The goal of prevention lies in giving the qualified pilot more resources to increase awareness and to prevent the CFIT accident. There are two ways to begin to decrease the risk of CFIT accidents. Either the qualified pilot receives more training or the qualified pilot is given better technological resources in the cockpit. Ideally, the qualified pilot will have both.

To eliminate as much human error as possible, technologies have been developed to assist the pilot. There are a variety of systems available for all areas of aviation but the technology of the Enhanced Ground Proximity Warning System is considered to be the most useful advance to date. Flying Magazine has called it “one of the most important safety advances in decades.”[5] EGPWS is prohibitively expensive for use in General Aviation so this paper will focus on the description and use of the EGPWS technology in the commercial airline industry.

What was needed in the cockpit was a system that would monitor the flight path and provide a warning to the pilots if impact with terrain was imminent before any unusual flight maneuvers would have to be employed. Prior warning systems were interfaced with the radio altimeter, which had limitations. The older systems would keep track of the airplane’s height via the radio altimeter settings and then give an aural alarm if a downward trend was detected. It would only give indications based on correct altimeter settings and did not have the ability to “look ahead” of the airplane to detect possible terrain collisions. The EGPWS was a major improvement for the simple fact that it would utilize a terrain map database via Global Positioning Systems to provide the pilots with a more reliable source of data. It would give a visual and an aural warning for terrain warnings.   The warnings sound approximately 60 seconds before terrain impact giving ample time for the pilot to make corrections. The older Terrain Warning Systems would give only 15-30 seconds warning before terrain impact.

The early EGPWS interfaced only with the Flight Management System on the aircraft. This interface worked well within the contiguous United States and Europe but in the more remote areas of the world such as Africa the EGPWS data had to rely on possibly outdated terrain data in the FMS. The original intent of Honeywell’s EGPWS was to have the system download independent GPS input and provide accurate terrain display no matter how old the FMS data might be.

The Austrian writer, Karl Kraus said, “The development of technology will leave only one problem: the infirmity of human nature.”[6] With all new technological advances, it would be a useless application if it were not an intuitive tool for the pilots for whom it may save. Before working on the technical aspect of the hardware, the engineers recognized that abiding by the FAA recommendation to consider the human factors in presenting a new function in the already familiar cockpit would be a solid course of action.

The FAA understands that before the engineers devise new technologies they should first consider the human factors framework in which this new technology will be used. To that end, the FAA published a report in 1996 which in part states, “Recommendation Processes-1: The FAA should task an aviation industry working group to produce a set of guiding principles for designers to use as a recommended practice in designing and integrating human-centered flight deck automation.”  And “Recommendation SA-3: The FAA should encourage the aviation industry to develop and implement new concepts to provide better terrain awareness.”[7]

The older terrain warning systems had a set of functions that are now considered standard. They include warnings for Rising Terrain, Excessive Descent Rate, Descent After Takeoff, Terrain Clearance, Descent Below Glideslope, Alltitude Callouts, Smart

500 foot Callout, Excessive Bank Angle Warning and Tail Strike Warning.

The enhanced features of the Enhanced Ground Proximity Warning System that earned the system it’s accolades are as follows:   Enroute Terrain Display – PEAKS, A Detailed Terrain Database, Obstacle Database, All publicly Known Airports, Look Ahead Algorithms, Terrain Alerting,  Pop-up feature, Geometric Altitude and Envelop Modulation.

Enroute Terrain Display-Peaks

Flying is a visual activity so care in considering how to display the information is of high priority. One display issue is what colors should be used for terrain awareness. One universal standard color scheme would be followed in the use of Red, Yellow and Green. Red is an urgent warning for the crew to take action, Yellow signifies that the crew should be aware of the terrain, Green symbolizes that the crew is in the clear and no action would be necessary. The color palate is used in the same manner as it is used in the outside world. For example, consider a traffic stoplight, Red is the color used to denote a definitive Stop signal, Yellow provides a caution warning and Green is an all clear. Utilizing aspects from other areas of life to match how to respond to various display indications in the cockpit will decrease the possibilities of negative transfer. Negative transfer is defined as “the interference of previous learning in the process of learning something new, such as switching from an old manual typewriter to a computer keyboard.”[8]

“The EGPWS terrain display utilizes five colors; red for terrain well above the aircraft, yellow for terrain slightly above and below the aircraft, green for terrain well below the aircraft, cyan for significant bodies of water and black for no threatening terrain.”[9]

During daylight hours the colors are more brightly displayed in order to be more visible to the flight crew. As slight a difference this may sound, the brightness factor could be critical. In an aircraft I recently started flying, I had thought that my Distance Measuring Equipment (DME) was INOP and I had chosen a different instrument approach than I had intended or even preferred. Later that evening, during dusk, I noticed that the DME was operating once again. It occurred to me that the DME was working all day but did not have a bright enough display to be seen during daylight hours. Fortunately, I did not have to rely on that cockpit instrument in order to safely complete the flight.

The PEAKS function will give highest and lowest terrain in feet of sea level numerically displayed on the side of the main map display. This allows for yet another level of increased awareness of the surrounding terrain.   The flight crew not only has the pictorial view of the terrain but it is reinforced by a graphical/numeric indication for a quick reference. The numeric display is color coded to correspond to the color coding on the terrain display. The number corresponding to the highest peak and lowest peak in the area will be displayed in whatever color it is represented on the display.

Detailed Terrain Database/Obstacle Database/All Publicly Known Airports

With Interfacing the Terrain display with a Global Positioning System the EGPWS is able to provide the flight crew with a more accurate terrain display than previous models used.

Look Ahead Algorithms

The display would not only need to show appropriate colors but also give correct terrain information in a timely manner. A major improvement that was needed to assist the flight crew was a longer lead time in order to respond to aural and visual warnings of impending terrain impact. Earlier systems would give a 15-20 second warning but often this was not enough time. Flight crews, when faced with a system that in the past has “cried wolf” and alerted the crew of impending terrain impact but was actually a false warning created an “accident waiting to happen” scenario. When a crew is given 15-20 seconds to respond to a terrain avoidance warning but takes time to discern whether or not it’s a true or false warning the hesitation to pull-up may put the flight in danger. One case to consider is the USAF 737-200 that crashed into a hillside while flying an NDB approach into Dubrovnik, Croatia carrying U.S. Secretary of Commerce, Ron Brown. The flight was off course, to the left of the inbound course of the approach, and installed on the airplane was an early model terrain avoidance system. The investigators could not confirm if the system was operational. If operational, the flight crew would have received a terrain warning 20 seconds before the impact. In this case, that was not enough time to execute the pull-up and avoid the accident.[10] The engineers on the EGPWS project were charged with the responsibility to increase the visual and aural warning to occur with enough lead time for the flight crew to respond. The EGPWS will provide warning indications 60 seconds before terrain impact. Considering that the flight crew might not be expecting this warning, the 60 second lead time gives adequate warning for the flight crew to react and respond.

A global terrain database with 100% coverage is resident within the EGPWS. By using the input latitude, longitude, altitude as well as flight path angle, turn rate and ground speed, the EGPWS can place the aircraft position within the terrain data and “look ahead” to potential conflicts with terrain. This eliminates the problem of abruptly rising terrain and gives greatly enhanced warning times for most CFIT situations. Software algorithms look down, based on flight path angle and nearest runway; ahead, based on aircraft ground speed; aside, based on roll angle; and up, by about 6 degrees.

Terrain Alerting

If any terrain is “seen” in the database by the algorithms, annunciators are illuminated and the voice “Caution Terrain” or “Terrain Terrain Pull Up” is given. The algorithms are designed to provide about 60 seconds advance alert to conflict with terrain. The first aural warning of “Caution Terrain” is in a more quiet or low tone so that it may be easily distinguished from the louder and more urgent callout of “Terrain!  Terrain! Pull Up!”[11]

Pop-up Feature

Another enhanced feature of the EGPWS is the ability to have the display map “pop-up” or be overlaid on the cockpit’s weather radar system so that the flight crew may have a more integrated picture of weather and terrain. Putting the two systems together with the Pop-Up feature may help eliminate errors when a flight crew member must look at two different displays in order to interpret the flight condition in relationship to terrain and weather.

Geometric Altitude

As mentioned previously, many of the CFIT accidents in prior years could be attributable to altimeter miss-sets. The EGPWS uses a geometric altitude that blends improved pressure altitude calculations, GPS altitude, radio altimeter, and terrain and runway information to eliminate the reliance on human data input. This feature alone may go a long way to reduce the number of CFIT accidents each year. One statistic claims that 25% of all CFIT accidents are attributable to miss-set altimeters.[12]

Envelop Modulation

One feature of the EGPWS is the capability to customize the alert system at certain geographical locations in order to reduce nuisance warnings and provide extra alert time if necessary.

Maintenance

In considering human factors in relationship to the maintenance of the EGPWS, automating the tasks of updating and maintenance is a prime concern of the design team. Automation should be incorporated to make a task simple to perform to achieve a more correct output. The role of human interaction should not be so difficult or tedious as to prohibit or discourage the task to be performed. The person responsible for ensuring the EGPWS is up to date and operating correctly should be able to accomplish these tasks effectively through automation.

Access to correct and updated databases is critical to flight safety. The EGPWS Terrain Database requires updates to remain the most useful to the flight crews but regulations are not in place to require such updates.   Even though not required to do so, Honeywell makes available three updates per year which they provide at no additional cost knowing that easy access to the information will help the flight crews stay informed on critical flight data.  The EGPWS operators are able to sign up for an email notification that a new database download is available. The database is available through the internet and takes only 30 minutes to complete once downloaded onto a card that interfaces with the EGPWS system.[13]

Honeywell makes available to EGPWS operators many tools to assess whether or not the EGPWS unit is working correctly. On their website the company has available a step-by-step self test guide as well as a real-time assessment of why a false terrain warning may have been activated.

With Human Factor considerations in mind the engineers worked to create a product that interfaced well between Humans and Technology. Unfortunately, it is impossible to prepare for all situations. There was one interesting problem that arose as a result of a disconnect between what the engineers designed and how avionic technicians interpreted the technological indication. An article in Avionics News stated the problem this way, “The biggest mistake technicians make when troubleshooting the EGPWS is using illumination of any cockpit failure annunciators (GPWS INOP, TERR INOP, W/S INOP) as a reason for removal.”[14]

Taking the statement on its face value, how could one fault the technicians for removing critical equipment that appeared to be indicating a failure. The Avionics News article goes on to explain the failure signal indicates a lack or failure of the required input signal and not a failure of the EGPWS unit itself. The technicians would remove the EGPWS unit and send the unit back to Honeywell for the company to test. Honeywell had so many returns of equipment in which no problems were found that they have begun to charge customers for returns of units for which no self test was performed prior to sending the units to Honeywell.

This disconnect issue was that on a different part of the display panel another indication would be illuminated to verify that the computer is fine. So if there is an INOP indication the technicians should have tried to troubleshoot via a self test procedure detailed in the manual rather than remove the equipment itself. The technicians did not make the connection between the two displays. The FAA suggests that when designing error messages the engineers should incorporate multilevel message. “The system shall provide more than one level of error messages, with successive levels providing increasingly detailed levels of explanation.”[15] If the failure indication utilized a more multilevel approach to error messages perhaps the technicians would have been able to more easily understand the failure indication thus not wasting company time in removing operable equipment.

No where in the article was it suggested that the engineers may have prevented this misunderstanding, that was quite prevalent, by considering Human Factors in the design of this failure of signal input indication.

The company does make available to EGPWS operators many tools to assess whether or not the EGPWS unit is working correctly. On their website the company has available a step-by-step self test guide as well as a real-time assessment of why false terrain warnings may have been activated which makes flight testing unnecessary. This is major cost cutting measure in terms of fuel for the operators of the EGPWS.[16]

The success of EGPWS can be measured by the number of CFIT accidents that have been prevented. To date, EGPWS has been responsible for saving 27 different aircraft from CFIT accidents.[17] One of the prohibitive factors in getting this cutting-edge technology in all aircraft is the expense. There has already been some forward movement by the US Presidential Commission on air safety to mandate that all commercial air-carriers include the EGPWS system on all their aircraft. This federal push comes from the success of a 1994 mandate in which the FAA mandated the installation of GPWS into regional turbine aircraft with 10 or more passenger seats. Since the 1994 mandate not one aircraft from that fleet of about 1600 aircraft has suffered a CFIT accident in the USA. It is unclear how a mandate to install this technology would impact the economics of the airline industry but it would be a giant step toward the goal for a zero accident rate for commercial air-carriers.

[1] EGPWS Review (2004, February) Flying magazine

[2] Federal Aviation Administration Advisory Circular  (Publication No.61-134)  General Aviation Controlled Flight Into Terrain Awareness (2003, April 1)

[3] Flight Safety Foundation Priorities. (2001-2004) Page 2 Retrieved from
http://www.flightsafety.org/

[4] Federal Aviation Administration Advisory Circular  (Publication No.61-134)  General Aviation Controlled Flight Into Terrain Awareness, (2003, April 1)

[5] EGPWS Review (2004 February) Flying magazine

[6] Karl Kraus (1874–1936), Austrian writer. Trans. by Harry Zohn, originally published in Beim Wortgenommen (1955). Half-Truths and One-and-a-Half Truths, University of Chicago Press (1990).

[7] Federal Aviation Administration Human Factors Team Report on: The Interfaces Between Flightcrews and Modern Flight Deck Systems”,(1996, June 18)

[8] The American Heritage Dictionary of the English Language, Fourth Edition, 2000

[9] Getting the Job Done-Part 1, Avionic News, March 2004

[10] Honeywell document 3.3;(2002,  January 21)  accessed from
http://www51.honeywell.com/aero/Products-Services/Avionics-Electronics/EGPWS-Home.html?c=21

[11] EGPWS Saves Lives (2004) [electronic version] Retrieved from
http://www.egpws.com/general_information/broxhures/EGPWS_Saves_Lives.pdf

[12] EGPWS Saves Lives (2004) [electronic version] Retrieved from
http://www.egpws.com/general_information/broxhures/EGPWS_Saves_Lives.pdf

[13] Honeywell document (2004, January) accessed from
http://www51.honeywell.com/aero/Products-Services/Avionics-Electronics/EGPWS-Home.html?c=21

[14] Getting the Job Done-Part 2, Avionic News, May 2004

[15] Federal Aviation Administration Human Factors Team Report, Human and Computers Interface, Error Messages, (1996, June 18)

[16] Honeywell document (2004, January) accessed from
http://www51.honeywell.com/aero/Products-Services/Avionics-Electronics/EGPWS-Home.html?c=21

[17] Honeywell document (2004, January) accessed from
http://www51.honeywell.com/aero/Products-Services/Avionics-Electronics/EGPWS-Home.html?c=21

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For one, human language differs because it has form and meaning, which means it has a structure which combines sounds, gestures, letters, and written words which when put together have a certain significance or meaning.  Secondly, human language differs because it is creative, meaning that we can (with language) produce (and understand) an infinite number of new sentences which have never before been spoken; we can lie and joke and even talk about things that don’t make any sense.  Thirdly, human language differs because it has displacement, which basically means that we as humans can talk about things in the past and future, and things that are either right in front of us or miles away.  While some animals, like bees, have shown signs of limited displacement, and while certain apes have been able to acquire a number of sign language messages, animal communication is restricted to very simple messages like “look out” or “danger!”  Animals cannot say “look out, I saw a snake in that tree yesterday” or make jokes, lie, and talk about the imaginary (which linguists refer to as the ability to use tropes).

Many researches have tried to teach primates language, and while some chimps and apes have been more successful than others in language acquisition, the end result has always shown that primates can only learn language to a certain extent, and usually only things related to stimulus-controlled phenomena like eating and drinking.  Language was only rarely spontaneous with these animals, they usually displayed redundancy and imitation, and no research shows them to have the same ability of language learning like a human child.  Gua was a chimp in the 1930s that was raised as a child along with the researcher’s own baby son.  Gua understood more words than the human boy at sixteen months, but never learned any more than that, while the boy of course did.  Among other things, primates have a different vocal apparatus than ours which prevents them from producing spoken language.  Research has simply shown that primates are not capable of learning human language.

Non-primates have shown an even lesser chance of acquiring human language.  Dolphins have shown the ability to understand and act on certain commands, but they have not displayed understanding for “novel utterances, metaphors, jokes, and lies.”  Not to mention the fact that producing spoken human language is simply impossible for these animals.

Like other animals, dolphins also have a limited number of messages which they produce amongst each other.  Dolphins, as well as apes and other animals have no way of communicating about the past, expressing their feelings, lying to each other, and among other things, talking smack about their enemies.  Human language, however, differs because it gives us the ability to do all of those things and more.

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What are Pheromones?

The definition of a pheromone, according to the Oxford dictionary, is: “a chemical substance secreted and released by an animal for detection by another usually of the same species. ” Basically, pheromones are chemical messengers that activate physiological or behavioral responses in other like organisms. In most mammals pheromones are detected within the vomeronasal organ (VNO). In human beings, however, it is hypothesized that they are detected and processed in the olfactory bulbs within the brain. The olfactory bulbs are located near the hypothalamus, which is the part of the brain that controls sexuality.

Pheromones are actually modified hormones or molecules used in trace amounts in order to control bodily functions ranging from cell-cycle regulation to production and release of other chemicals and proteins. Most importantly, they are hormones responsible for the behavioral responses of individuals – sexual behavior included.

Where Are Pheromones Found?

Pheromones have been isolated in saliva, sweat, and urine of different species, including humans. Most mammals have a specific organ for the detection of pheromones; however, it has not yet been assessed whether the pheromonal communication depends solely on that organ. While “odorant detection is mediated by millions of olfactory sensory neurons located in the olfactory epithelium lining the nasal cavity” of the first olfactory system, “the vomeronasal organ, a separate olfactory structure in the nasal septum that opens into the nasal cavity” mediates the pheromone perception in the second olfactory system (Buck, 2004, p. 184). These two systems are very similar to each other.

It is proposed that humans can detect around 10,000 different odors and which is accomplished with the use of around 350 odorant (olfactory) receptors ,or ORs (Buck, 2004, Kien & Storm, 2004). ORs are transmembrane proteins embedded in the cell membrane of the sensory neurons or the olfactory epithelium. These transmembrane proteins are coded in the DNA and several studies show that “each neuron may express only one gene,” therefore only one type of an OR is found in the cell membrane (Buck, 2004, p.184).

How is it that humans only have 350 odorant detectors but can detect over 10,000 different compounds? The answer is that the 350 ORs have additive effects. Each OR binds to a specific chemical or odorant molecule which causes a cascading sequence of events within the cell

… one OR can recognize multiple odorants and that a single odorant is detected by multiple ORs, but, importantly, different odorants are recognized by different combinations of ORs. This indicated that the OR family is used in a combinatorial manner to encode odor identities. (Buck, 2004, p.185)

The combination of activation of several of the 350 ORs encodes a particular odor which is then passed trough the olfactory bulb to the olfactory cortex.

The second system that uses the VNO has a similar processing pathway. There are between 120 and 140 receptors in the VNO in mice – significantly less than around a 1,000 found in the olfactory epithelium of mice (Buck, 2004). This is a general trend in most mammals. There are usually two families of receptors: V1Rs and V2Rs – vomeronasal receptors which are not to be confused with the olfactory receptors. These receptors are similar in form and function to the ORs and can detect a variety of chemicals. Once pheromones are detected by vomeronasal receptors “sensory signals are relayed from this organ [VNO] through the accessory olfactory bulb and then targeted to the medial amygdala and hypothalamus, areas implicated in the hormonal and behavioral effects of pheromones” (Buck, 2004, p.184). One major difference between the two systems is that while a few of the vomeronasal neurons equipped with VRs can detect more than one pheromone, most neurons that can detect only one pheromone – a single receptor-type pheromone indicating a lock and key mechanism (Buck, 2004, Von Campenhausen, 2000).

How Many Types of Pheromones Exist?

Pheromones are essential to nonverbal communication between members of the same species. Human beings are, however, unaware of pheromones and the influence they have on the mating process as well as other areas of life. Pheromones play significant roles in the areas of relationships and reproduction. There are four main types of pheromones; releaser pheromones, primer pheromones, signaler pheromones, and modulator hormones. Releaser pheromones elicit an immediate response that is quick and reliable. Primer pheromones require more time than releaser pheromones to affect their intended. Signaler pheromones provide information and modulator pheromones can both alter and sync bodily functions.

Releaser pheromones are generally associated with sexual attraction. Primer pheromones affect the development or reproduction physiology, including puberty, cyclicity in females, the success or failure of pregnancy, and shifts in hormone levels (Wysocki & Pereti, 2004). It has been hypothesized by Wysocki & Pereti (2004) that in other mammals, if a female is exposed to male pheromones from a male other than the one who impregnated her, primer pheromones can cause the pregnant female to spontaneously abort the fetus. Signaler pheromones allow human mothers to recognize their newborns by scent alone. Fathers who attempt this sameprocedure fail. The signaler pheromones give us our genetic odor print, which is as unique as a fingerprint. Modulator pheromones, in the form of sweat, when placed on the upper lip of females shifted the mood of the subject. They were more relaxed and less tense than the control group, and they also have an impact on women’s monthly cycle.

Of these four types of pheromones there are also four specific functions of pheromones: opposite sex attractants, same sex repellents, mother infant bonding, and menstrual cycle modulators. Pheromones activate specific regions within the brain. They affect social behavior, regulate ovulation, and modulate physiological parameters such as the serum levels of testosterone, luetinizing hormone and follicle stimulating hormone. Pheromones have also been shown to affect respiration and cardiac frequency in a gender specific way (Beier, K. , Ginez, I. , & Schaller, H. , 2004).

Introduction to Pheromones – 1

Opposite-Sex Attraction – 2

Same-Sex Attraction – 3

Mother-Infant Bonding – 4

Menstrual Cycle Modulator – 5

Conclusion & References – 6

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Ponty then goes on to discuss more specifically why physiology alone, or why psychology alone cannot account for the phenomenon of phantom limbs. Rather Ponty attempts to understand how each complements the other; the body the mind and the mind the body.

He begins with the example of a man who has lost his leg. Stimulus is applied to, instead of the leg, the path between the stump and the man’s brain. It is then realized that the man will experience, once again, the feeling of his leg. Why is this? Ponty begins with the physiological, mechanistic approach, but soon reveals its shortcomings.

“What has modern physiology to say about this [phenomenon]? Anesthesia with cocaine does not do away with the phantom limb, and there are cases of phantom limbs without amputation as a result of brain injury. Finally, the imaginary limb is often found to retain the position in which the real arm was at the moment of injury” (428). This leads Ponty to the conclusion that physiology alone cannot account for this phenomenon; the psychic realm must also play a role.

He believes the phenomenon of phantom limb can be understood more completely if we are able to understand a similar phenomenon, that of anosognosia. Anosognosia is the phenomenon that occurs when a patient retains a limb, but refuses to acknowledge its presence. Ponty explains these patients “who systematically ignore their paralyzed right hand, and hold out their left hand when asked for their right, refer to their paralyzed arm as ‘a long, cold snake’, which rules out any hypothesis of anesthesia and suggests one in terms of the refusal to recognize the deficiency” (428). This phenomenon clearly demands a psychological explanation. But is a psychological explanation enough to account for phantom limbs? Ponty doesn’t think so: “…no psychological explanation can overlook the fact that the severance of the nerves abolished the phantom limb. What has to be understood, then, is how the psychic determining factors and the physiological conditions gear into each other.”

But this phenomenon cannot be understood simply as a combination of the psychic and the physical forces. It must be understood in terms of the person, as the living body rising toward the world with its various projects in mind as it does so; it must be understood as the relationship between the subjective person and the objective world.

Ponty then applies this view of the subject/object to the physiological and psychological explanations, pointing out their essential shortcomings. Along the way he begins to borrow an idea from psychoanalysis, the idea of repression. A purely physiological explanation of anosognosia and the phantom limb could be conceived of as the repression of what Ponty calls “interoceptive” stimulations. According to this idea, anosognosia would be the “absence of a fragment of representation which ought to be given, since the corresponding limb is there; the phantom limb is the presence of the part of the representation of the body which should not be given, since the corresponding limb is not there” (430). But this makes no sense, if a part does not exist it should not be represented, and vice versa. But the psychological account doesn’t do much better.

In the psychological account, the phantom limb is viewed as a memory or a perception, while anosognosia is forgetfulness or a negative perception. In this case the phantom limb is viewed as an actual positive perception of an entity which does not exist, while anosognosia is thought of as the absence of an actual presence, which, again, makes little sense.

Ponty resolves these issues by realizing that in both cases we are relying on the outside world and its inherent characteristics, which is problematic. He says, “In both cases we are imprisoned in the categories of the objective world, in which there is no middle term between presence and absence. In reality the anosognosic is not simply ignorant of the existence of his paralyzed limb: he can evade his deficiency only because he knows…what he does not want to face, otherwise he would not have been able to avoid it successfully” (430).

This is a critical point Ponty is trying to make. Just as in the psychoanalytic tradition, the patient can only be aware of and act on the basis of what he or she knows. In the case of the phantom limb patient and the anosognosic, each is aware of the deficiency and is attempting to make up for it on what could be considered the subconscious level. The anosognosic denies knowledge of the paralyzed limb in order not to feel the pain of the handicap, while the phantom limb patient demands that his exists for the same reason, so as not to be rendered handicapped.

This is what Ponty means when he says, “The phantom arm is not the representation of the arm, but the ambivalent presence of the arm” (430-431). There is no deliberate decision made by the patient to deny existence or assert existence (depending on the case), but it comes from something deeper. Ponty says that it finds its genesis elsewhere, not in the patient declaring: “I think that…”, but it needs-to-be for the patient.

This idea hinges on the aforementioned projective outlook of the living-body toward the world. The living-body views the world in terms of projects it wishes to accomplish, and to do this the body becomes unperceived as it learns to perform certain skills. The body, in this sense, is comprised of two layers: the habitual and the present. The habitual is that which we have learned to do and can do without thinking (turning a doorknob or tying a shoe). These skills are put at the disposal of the present body, and because one does not have to think about them, to bring them into the present body, they do not intrude upon the present body. When, as a young child, one learns to turn a doorknob, this becomes part of the habitual body and can be utilized by the present body.

The problem approaches when something interrupts this transmission from habitual body to present body, i.e. a disfigurement or a handicap. In this case, an amputated arm for example, the present body can no longer rely on the habitual. The tying-of-the-shoes becomes impossible, as well as the opening-of-the-door. This causes great pain for the patient and may result in the phenomenon of phantom limb or anosognosia, as a way for the patient to continue it his or her existence. The patient never really deals with the situation, but covers it up somewhat; thus the analogy to psychoanalytic repression.

So here we can come to understand that a merely physical or psychological explanation of the phenomenon of phantom limbs or anosognosia are lacking. The patient must be viewed as occupying a middle ground between the two. He builds a self through his past and relies on it in the present and in toward a future horizon. When this reliance is disturbed through a handicap, the patient must act (or not act) in someway so that he may continue in his existence. Often this results in a repression of the malady so that the patient believes he will continue on his same path, relying on his past and directing his living-body toward the future.

Mooney, Timothy & Moran Dermot, eds. The Phenomenology Reader. Routledge Publishing, London and New York. 2004. (Reprint of The Body as Object and Mechanistic Pysiology)

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Thermophiles are perhaps one of the most interesting varieties of the extremophilic organisms. These microorganisms are those that can thrive at temperatures over 50°C (9). Based on their optimal temperature, thermophiles can be subdivided into three groups: slight thermophiles with an optimal temperature between 50°C and 64°C and a maximum at 70°C, extreme thermophiles with an optimal temperature between 65°C and 85°C, and finally hyperthermophiles with an optimal temperature above 85°C and a maximum above 90°C (9). (For the purposes of this paper, the term “thermophile” will refer all organisms with the ability to thrive at temperatures above 50°C, unless otherwise noted.) It was previously believed that life could not thrive at temperatures above 113°C, however recent discoveries have found a microbe called strain 121 that is able to grow at 121°C and can survive at 130°C (1). This changed the way many scientists look at the temperature dependence of life. As of 2001, over sixty species of Bacteria and Archea have been isolated and grown between 80°C and 110°C (9). Of the thermophiles, there are a much higher number of anaerobes than aerobes. This is most likely due to the fact that oxygen is much less soluble at higher temperatures and therefore is not available for organisms to use in metabolic processes (9). Thermophiles can grow in both terrestrial and marine environments, including: solfataric fields, geothermal soils, volcanically heated surface waters, hot fumaroles, deep-sea vents, and even black smokers (2). These can also thrive in biotopes created by man, such as smoldering coal refuse and geothermal powerplants (2).

Due to the hazards of living at such extreme temperatures, thermophiles have evolved a variety of mechanisms that allow them to survive at temperatures no other organisms can thrive at. These traits include unique membrane lipid composition, thermostable membrane proteins, and higher turnover rates for various protein enzymes (9). One of the most important attributes to the maintenance of homeostasis within the organism is that of the plasma membrane surrounding the organism. Archaean thermophiles, and also acidophiles, have membranes containing unique ether lipids (2). These tetraether lipids span the entire membrane forming a rigid monolayer that is impermeable to both ions and protons (2). Ether-type lipids, such as these, are much stronger than the ester-type lipids found in non-thermophilic Bacteria and Eukarya (2). Also, the lipid composition in the membranes of the thermophiles consists of more branched and saturated fatty acids than other organisms (9). Having a stronger lipid complex within the membrane helps the Archaean thermophiles to withstand higher temperatures better than other organisms. Aside from having to stabilize the plasma membrane at high temperatures, thermophiles must also stabilize their proteins, DNA, RNA, and ATP. As of now, the process of heat stabilization for DNA, RNA, and ATP is unknown (2).

Thermophiles have developed distinct ways of heat stabilizing the proteins that are required for the maintenance of life. For one, the surface energy of the protein, along with the hydration of the non-polar groups that are exposed, are minimized (2). Also, hydrophobic regions are packed into a very dense core of the protein by charge-charge interactions between amino acids (2). There is also an increase in salt bridges and other networks, which help to stabilize the structures at higher temperatures (2). Finally, it has been shown that there is a distinct increase in the synthesis of chaperonin proteins after a heat shock (2). Chaperonins are proteins that unfold and help refold proteins that are not folded properly enough to perform their required function (4). Increasing the number of these during high temperatures, most likely allows the cells to have second chance at folding proteins that misfolded due to high heat (2).

Another group of extremophiles that have adapted themselves to an extreme environment are the halophiles. These organisms have the ability to grow at very high salt concentrations (2). In this case, the salt concentrations can be anywhere from 3% to 35% (2). Commonly, this group of extremophiles can be found in such environments as sea water, hypersaline lakes (the Dead Sea, the Great Salt Lake), and saline souls (2). Halophilic organisms can also be found in man-made saline environments such as salted foods and tanned hides (2). Much like thermophiles, halophiles can also be broken down into three different groups; instead of optimum growth temperature, the groups are based on optimum salinity. There are slight halophiles that grow at an optimum salinity 2% to 5%, moderate halophiles that grow at an optimum salinity of 5% to 20%, and finally extreme halophiles that grow at an optimum salinity of 20% to 30% (6). Also, some organisms are referred to as “halotolerant,” meaning that the organism has the ability to grow in bother hypersaline environments and non-saline environments, but saline is not required for optimum growth (6).

An interesting feature of hypersaline environments is the formation of gradients in concentration with respect to time. As small bodies of hypersaline waters evaporate, the salinity gradually increases. The salinity of water can start at 1M NaCl, but as times goes by the salinity can increase to over 5M NaCl (6). This causes natural fluctuations in the halophilic species that inhabit that particular body of water. For example, when water is around 1M to 3M NaCl, the environment tends to be filled with algae, protests, and yeasts (6). However, when evaporation occurs, and the salinity increases 5M, those organisms die off because they cannot survive at such high salt concentrations. Organisms that can survive at these higher salt concentrations, such as red-orange halobacteria, drastically increase in numbers until the body is completely dried up or diluted back to a lower concentration (6). The increases in red-orange halobacteria populations are very dramatic and blooms can be as dense as 10^8 cells per mL (6). However, no matter what level of salinity the organism can thrive at, all halophiles face difficulties in surviving.

One of the biggest problems faced by halophiles in maintaining homeostasis is the balance of osmotic pressure. Since these organisms are in hypertonic solution, water diffuses out of the cells and into the surrounding environment. This even would cause non-halophilic organisms to plasmolyze or, if the organism does not have a cell wall, the organism would shrivel. Both of these reactions would be lethal to the organism (4). Usually, the organism would take up sodium ions to create equilibrium between the interior and the exterior cellular environments. However, since sodium ions at such high concentrations would be potentially lethal within a cell, most halophiles accumulate potassium ions while actively expelling sodium ions to create osmotic equilibrium (2). Aside from potassium ions, halophiles also accumulate other non-disruptive solutes to maintain equilibrium. These can include amino acids, glycine, betaine, ecotine, and sucrose (6).

Other problems faced by halophiles include: protein structure and membrane structure. In order to combat denaturation, aggregation, and precipitation of proteins at high salt concentrations, halophiles proteins often contain a high ration of acidic to basic amino acids, thus giving the surface of the proteins a negative charge (6). It is believed that this negative charge allows the proteins to be solvated in a high salt environment (6). Halophile membranes are unique in their composition, just as thermophiles are. Some halophiles make use of the protein bacteriorhodopsin (6). This compound of bacterioopsin and retinal is found in the membranes of some halophiles in lattice shaped areas, giving the membrane a purple color and sometimes covering more than 50% of the entire membrane surface (6). The function of this protein is to act as a light dependant proton pump (6). When induced by a drop in oxygen levels or a high intensity of light, this protein can help support phototropic growth (6). Halophiles also have novel gas vesicles to allow flotation of the organisms in liquid and into higher depths where more oxygen may be available, or where the salt concentration is at optimum range (6).

Another form of extremophilic living is the ability to live in pH levels lower than neutral. Organisms that inhabit the niche between pH 0 and pH 4 are termed acidophiles (2). These organisms often have the ability to grow at high temperatures as well; organisms that can do as such are called thermoacidophiles (2). Acidophiles can inhabit any niche within the bounds of low pH, however the only one genus is known to thrive at pH 0; the genus Picrophilus has the uncanny ability to grow aerobically at 60°C and at pH 0 (8).

Living at such low pH’s is not easy, so acidophiles have evolved ways to overcome the difficulties. For one, the internal pH of the cell is maintained as close to neutral as possible, usually between pH 5 and pH 7, n order to avoid the denaturation of proteins and other molecules (8). However, Picrophilus oshimae has been recorded as having an internal pH of 4.6 (8). Also, the cellular membranes have a very low protein permeability to keep stray protons from an acid out of the cytoplasm (8). In order to maintain the internal pH, acidophiles either actively excrete protons or use them in various metabolic reactions such as the reduction of oxygen in the membrane, before the acidic protons can cause internal cellular damage (8). Acidophiles also utilize non-energy processes to maintain internal pH. These include the maintenance of fixed negative charges on intracellular molecules and the upkeep of a proton diffusion potential (8). Protein enzymes must also be modified in order to keep from being denatured. Acidophilic enzymes have the charged amino acids replaced by neutral polar amino acids in their polypeptide chains (8). This reduces the electrostatic repulsion that occurs between charged groups at low pH, thus enhancing stability (8).

Living at the opposite end of the spectrum from acidophiles are alkaliphiles. These organisms thrive in environments with a pH between 10 and 12, with an optimum growth pH of about 9 (7). Alkaliphiles also have the ability to live in neutral and even acidic environments (7). Of interesting note, is the fact that when alkaliphiles are placed in a neutral or acidic environment, they have the ability to change the environmental pH to a more optimal level (7). In order to survive at these levels, alkaliphiles have novel adaptations to cell wall structure. It has been shown that the cell wall of alkaliphiles contains a variety of acidic compounds, including: phosphoric acid, aspartic acid, galacturonic acid, glutamic acid, and gluconic acid (7). Having these negatively charged amino acids in the membrane allows the cells to better absorb sodium ions and hydronium ions (due to their positive charges),while at the same time repel the hydroxide ions which are in high concentrations at high pH levels (7). Having a membrane capable of this feat allows alkaliphiles to grow at pH levels higher than any other organism.

A final type of extremophilic organism is the group called piezophiles. Piezophiles are organisms that have the ability to grow at pressures higher than normal atmospheric pressure (10). The majority of piezophiles can also be categorized by the temperatures where they thrive: thermopeizophiles grow in high temperatures and pressure while psychropeizophiles grow in low temperatures and high pressure (10). Piezophiles are found underwater, at virtually all depths. Depending on the location of their underwater home, piezophiles are subjected o different temperatures. For example, the thermopiezophiles would be found around deep-sea vents (10). As for how these organisms have the ability to survive at high pressure, it has been difficult for scientists to show how piezophiles overcome this extreme. However, scientists are beginning to look at the cell membrane to see if piezophiles have a unique membrane composition or structure that would allow them to survive at the greatly increased pressures (10).

Thermophiles, halophiles, acidophiles, alkaliphiles, and piezophiles all take life to the extreme. By studying these unique organisms, scientists can gain insight into how life arose on the Earth and even infer as to how life would be able to exist on other planets. According to professor Michael Danson, a biochemistry professor at the University of Bath in the UK, “By studying how organisms live and thrive in places like the Antarctic, if we can understand how these organisms operate, then we will have a good starting base by which to find life and study life on Europa” (3). As for the origins of life on Earth, some scientists are looking to the extremophilic microbe Dienococcus radiodurans. This extremophile has the unique ability to survive radiation at several thousand times the lethal dose for humans (5). Researchers in St. Petersburg attempted to induce this type of radioactive resistance in E. coli. They subjected the bacteria to gamma rays to kill 99.9% of the population. After allowing he survivors to recuperate, they repeated the cycle. After 44 cycles of gamma radiation, it took 50 times the original dose to kill 99.9% of the population (5). Using their data, they found that it would take thousands of these cycles before the E. coli were as resistant to radiation as the Dienococcus. They have calculated that it would take somewhere between one million and a hundred million years for Dienococcus to have acquired this resistance on Earth (5). However, these researchers feel that if this microbe had evolved on Mars, it would have been able to acquire this level of resistance in a much more reasonable time due to the amount of radiation that Mars’ surface is subjected to (5). However, it has not yet been shown that this organism did evolve this ability from living on Mars, as of now it is merely a story.

Stories like the previous are bound to appear. Extremophiles have found a way to fill niches on Earth that no other organism can even fathom to survive in- showing that life will find a way to survive almost any conditions it happens to find itself. The environments on Mars and Europa are not a far step from the extreme locales here on Earth. The variety of unique adaptations that extremophiles here on Earth have developed could very well translate to other worlds. By continuing to study these organisms, scientists will continue to discover just how extreme life really is.

Works Cited

1. (2003) Some like it hotter. Science News. 163(123), 366.
2. Antranikian, Garabed. (January 2001). Extremophiles. In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.
3. Black, H. (2002). Extremophiles: They love living on the edge; these microbes, with possible ties to outerspace, call fire and permafrost home. The Scientist. 16(14), 36-37.
4. Campbell, Neil A., and Reece, Jane B. (2002) Biology (6^th ed.). San Francisco: Benjamin Cummings.
5. Clark, S. (2002). Did living on Mars build up a microbe’s resistance to radiation?.
   New Scientist. 175(2362), 16.
6. DasSarma, Shiladity, and Arora, Priya. (July 1999). Halophiles. In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.
7. Horikoshi, Koki. (April 1999). Alkaliphiles. In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.
8. Norris, Paul R. (March 2001) Acidophiles In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.
9. Weigal, Juergen, and Canganella, Francesco. (October 2000). Extreme Thermophiles. In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.
10. Yayanos, A. Aristides. (December 2001). Barophiles and Peizophiles. In: Nature Encyclopedia of Life Sciences. London: Nature Publishing Group.

The rise and development of humankind is the primary source for the mass extinction that occurs today. From the times of Jesus until the year 1800, man contributed to the loss of one species every 55 years. This statistic could almost be considered natural, but then should be taken into account the later years. From 1800 to 1900, one species was sacrificed by and for mankind every 1.5 years. Between 1900 and 1990 that number rose to one lost species every year. The years between 1990 and 1995 contained a surge in population and use of resources and in effect killed 3 species each day. Today, the number is ever rising.

A rapid growth in human population has strained the Earth’s resources as well as its species. Around 40 to 50 years ago, the population of the world was about two billion. Today, that number is over six billion. The estimated population in the year 2030 is eight billion, which seems to be more than our planet is capable of handling under the current abusive circumstances. Most of the Earth’s resources are not able to be replenished and so will continuously deteriorate as the human population continues to escalate in its demand for them. These same resources also provide food and shelter for the animals which are or would become endangered; as the supplies of Earth are used up, the endangered species become extinct.

In addition to the problems of resource abuse, poaching, and habitat destruction, the introduction of exotic species into new habitats is one of the major factors that contributes to the loss of so many species that were native to that land. For example: in California, trout were introduced into a previously-fishless body of water to heighten the fishing industry. The effect of this decision, however, was the rapid decline in the population of frogs and other amphibians which lived in the immediate area. The best explanation reasons that the fish eat the frogs’ eggs and tadpoles, thus cutting off the lives of the amphibians before they have a chance of survival. Millions of dollars have been spent to eliminate non-native species from environments such as this to preserve the native species and ecosystems. Hopefully, the amount of money working against exotic species will discourage species displacement.

It is a proven fact that the diversity of species is the most important factor in the survival of an ecosystem. Pollinators, such as bees, help plant-life reproduce by transferring pollen from one flower to the next. These plants provide food for herbivores such as rabbits and deer. The herbivores’ numbers are kept in-check by their predators, the carnivores, which include wolves and big cats. In this way, neither the plants nor the herbivores are allowed to multiply exceedingly, and a balance is achieved. When this cycle is interrupted, however, and one species is lessened or completely removed, the results would be catastrophic to the species that are involved in even the least direct way. Half of the world’s diversity in species is contained in rainforests, which once covered 25% of the earth’s surface. Through the ravaging by mankind and through the afore-mentioned effects, however, they now cover merely 6%, and are growing thinner every day.

There are those who argue that the extinction of species is not a matter that needs immediate attention. The fact that some species that were once presumed extinct have resurfaced is very true; the cases of the black-footed ferret and Edward’s pheasant are only two in hundreds of such revivals. The problem, however, does not lie in the complete extinction of a certain species; the mere deterioration in a species’ population is enough to upset the ecological balance of a system. No one can tell for sure whether the last of any species has died; humans cannot feasibly scour the earth for a survivor. We can, however, notice when a species that was once abundant falls to a mere handful due to human intervention.

Some skeptics continue to argue that environmentalists are keeping the natural extinction processes at bay by attempting to save endangered species. The current extinction rate, however, ranges from 1000 to 10,000 times higher than natural extinction rates. This number is very alarming when the health of the ecosystem is taken into consideration. If the world continues on the path it is on now, two million species of plants and animals will be extinct by the end of this century.

There is an ethical duty to endangered species that lies within mankind. Species that become rare or extinct have an effect on other species, including humans, if only in an indirect way. By destroying resources, poaching, and ultimately rearranging the ecosystems of the world, humankind is in actuality playing God. No one can argue that we are qualified to do so. Man has the power to stop the chain reaction that is happening all over the Earth, and a deep responsibility exists to correct our own mistakes.

There are efforts in place to assist in the fight against extinction. In 1973, President Nixon signed the Endangered Species Act, which proved that the United States Congress recognized the plight of endangered species and the importance of saving them from extinction. By placing endangered animals on a protective list that made destroying these animals and their habitats illegal, these species were given the chance to multiply and regain the population they once had. In the years since the passing of this Act, nearly 1,000 endangered species of plants and animals have been placed on the list, and more than 40 percent of these are stable or improving. The Act is not perfect, however; there is a lack of enforcement of the laws it stresses, and so it is not as effective as originally intended.

Wildlife Reserve Networks are also being used to keep animals isolated from human civilizations and possible harm. These networks include three or more areas of untouched wilderness that span as wide as a population of a given species and are protected against human entry. Corridors connect these areas to allow for migration, and are also blocked off from humans. This system of zones allows humankind and endangered animals to share the land and resources without one taking advantage over the other.

Another solution, often called a last resort, is captive breeding. Endangered animals that are on the brink of extinction are captured and bred under sterile and stable conditions to ensure healthy offspring. These captive-bred animals then must be reintroduced into the wild in order to increase the population of that species. This, however, is a task that is seldom achieved to expectations. Animals that were raised in captivity are not prepared for the harsh wilderness and so have a smaller probability of surviving their first year on their own. The option of captive breeding is often the only one available; The efforts continue.

All species of plants and animals play a part in its fragile ecosystems and natural balance. No matter how small that part is, one species’ extinction could cause a chain reaction that could devastate the world as we know it. In order to help them, the Endangered Species Act must be taken as seriously as any other document of law. Punishments should be harsher and the tolerance level should remain unwavering and strict. The zones and passages in Wildlife Reserve Networks should be better protected; poachers still enter these areas and continue to destroy the endangered species that thrive within. Finally, the captive-breeding programs in zoos and other wildlife facilities should continue, and hopefully research will unveil a way to reintroduce these animals without worry of survival.

The world is a ship in treacherous waters, and the species that live on its surface are the only rivets holding the vessel together. Mankind has the power to choke the decline of populations, and there is yet more that can be done to save this ship from sinking.

Helen Cothran, ed., Opposing Viewpoints: Endangered Species (San Diego, C.A.: Greenhaven Press, Inc., 2001)”Total Midyear Population of the World: 1950-2050,” International Programs Center, US Census Bureau, http://www.census.gov/ipc/www/idb/

James P. Sterba, ed., Earth Ethics: Environmental Ethics, Animal Rights, and Practical Applications (Eaglewood Cliffs, N.J.: Prentice-Hall, Inc., 1995)

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The purpose of this lab was to identify an unknown mixture of two compounds using powder diffraction techniques combined with scanning electron microscopy and the “PC Identify” computer software. The X-ray powder diffraction pattern of the unknown mixture was analyzed on the computer in the laboratory. A peak search-match showed possible compounds contained in the mixture for further identification. An elemental analysis was conducted using a scanning electron microscope to determine which elements were present in the unknown mixture. Information from the XRD pattern and the elemental analysis helped identify the two compounds in the unknown by comparing it with the powder diffraction files. It was determined that unknown mixture mx3 contains potassium bromate (KBrO₃) and nickel oxide (NiO). The two compounds were verified using the “PC Identify” computer software.

Introduction:

Similar to the past week’s labs, this particular lab employed the use of powder diffraction techniques to identify an unknown material. In X-ray diffraction, specimens are powdered so that all orientations are uniformly represented. X-rays are electromagnetic radiation of wavelength 0.5-2.5 A, and occur in the electromagnetic spectrum between gamma-rays and ultraviolet light. In this experiment, a monochromatic source of X-rays was used. The X-ray powder diffraction technique is used to fingerprint crystalline materials and determine their structures. Each crystalline solid has a unique characteristic XRD powder pattern. Once a material is identified, X-ray crystallography can be used to determine its structure. In this experiment, an unknown mixture of two compounds was identified. The X-ray powder diffraction pattern of the unknown mixture was a superposition of each compound’s individual XRD pattern. By examining the XRD powder pattern with a peak search-match, the computer found possible compounds in the unknown mixture for further identification.

In the second part of the lab, scanning electron microscopy (SEM) was used to conduct an elemental analysis of the unknown mixture. The SEM uses electrons instead of light to form an image. A beam of electrons is produced at the top of the microscope by heating of a metallic filament. The electron beam follows a vertical path through a column of the microscope. The electron beam travels through electromagnetic lenses which focus and direct the beam down towards the sample. Once the beam hits the sample, either backscattered or secondary electrons are ejected from it. The interaction of the electrons in the SEM with the sample results in the generation of characteristic X-rays. Detectors collect the secondary and backscattered electrons, along with the characteristic X-rays, and convert them into a signal that is sent to a viewing screen producing an image. This process was used to determine the individual elements in the unknown mixture. For unknown mixture mx3 the elements detected were potassium, nickel, bromide, and oxygen.

In the third part of the experiment, the information from the elemental analysis and XRD pattern were used along with the powder diffraction files to determine the two compounds in the unknown. It was determined that unknown mixture mx3 contains potassium bromate (KBrO₃) and nickel oxide (NiO). This result was verified with the “PC Identify” software.

Experimental Procedures:

Part One: Powder Diffraction

The first steps to this experiment included logging into the X-ray diffraction computer program in the laboratory, choosing an unknown mixture of two compounds, and downloading the XRD powder pattern intensity graph. The intensity graph was optimized by stripping away the Ka₂ and smoothing the peaks. A chart of the d-spacings, relative intensity and scattering angle of the unknown mixture was created. D-spacing labels were applied to the graph. The graph and chart were printed and saved for later use. A peak search-match was done without restriction to find all possible compounds that might be in the mixture. These were recorded and taken to the scanning electron microscopy room.

Part Two: Scanning Electron Microscopy

The SEM was used to conduct an elemental analysis of the unknown mixture. The day this lab was conducted, Thursday October 13, 2005, the SEM was not working properly. Mr. Al Stewart ran the experiment earlier that morning and gave us his results. First a picture was taken of the sample. This picture is in the appendix and labeled Figure One: Scanning Electron Microscopy of mx3. Next, an elemental analysis of the mixture was carried out. Each compound in the mixture was analyzed by placing an “X” on it and EDEXing. On the resulting graph, the strong peaks show which elements are in each compound.

Part Three: Identification

The elemental information from part two was used with the diffraction data from part one to correctly identify the two compounds in the unknown. The diffraction data used to determine the compounds included the d-spacings, relative intensities and scattering angles. This information was compared with the powder diffraction files. In unknown mx3, the compounds were identified as potassium bromate and nickel oxide. The intensity graph from part one was re-opened. This time when trying to identify the unknown on the computer, the elements resulting from part two of the lab were set as restrictions. The “PC Identify” software verified the two compounds in the mixture. The computer also identifies which peak belongs to which compound on the XRD pattern. Powder diffraction files were used to determine which peak coincides with each compound. The crystal structure, lattice parameters, and space group for each compound were determined. Finally, the measured experimental relative intensities of each compound were compared with the theoretical data found in the powder diffraction file. An error analysis was completed on the results.

Results/ Calculations:

In part one, an unknown mixture’s XRD pattern was downloaded and analyzed. Several possible compounds resulted from the peak search-match. Among these were potassium bromate, nickel oxide and several others. The original experimental data is attached at the end of this lab.

In part two, first a picture of the sample was taken. This picture is located in the appendix and labeled Figure One: Scanning Electron Microscopy of mx3. An elemental analysis was conducted and revealed that the elements in the unknown mixture were potassium, bromide, nickel and oxide. This data is also in the appendix and labeled Figure Two: Elemental Analysis of mx3. Next, each compound in the mixture was analyzed. The results from the first compound are shown in Figure Three: Compound One. The strong peaks show that this compound consists of bromide and potassium. The results from the second compound are shown in Figure Four: Compound Two. The strong peaks indicate that this compound contains nickel and oxygen.

In part three, a comparison of the d-spacings, relative intensities and scattering angles to the powder diffraction files, allowed identification of the two compounds as potassium bromate and nickel oxide. This result was verified with the “PC Identify” software in the laboratory.

Nickel oxide is rhombohedral and has theoretical lattice parameters of a = 2.9552 A and c = 7.2275 A. The space group of nickel oxide is R3m. On the mixture’s XRD pattern, NiO has peaks at (101) and (012). Potassium bromate also has a rhombohedral crystal structure. Its theoretical lattice parameters are a = 6.014 A and c = 8.156 A. The space group of potassium bromate is R3m. On the mixture’s XRD pattern, KBrO₃ has peaks at (101), (012), (110), (003), (021), (202), (113), (211), (104), (122), (300), and (024). The (hkl) for each compound are labeled on the mixture’s XRD powder pattern in the appendix in Figure Five: mx3 XRD pattern with labeled (hkl).

The PDF card file for each compound is in the appendix labeled Figure Six and Figure Seven. The measured relative intensities for each compound were compared with the card file for the compound and an error analysis was conducted. The results are in the next two tables.

Table One: Comparison of Relative Intensities for Potassium Bromate

Table Two: Comparison of Relative Intensities for Nickel Oxide

Discussion:

The information from the X-ray powder diffraction and the scanning electron microscopy allowed for us to identify the compounds in the unknown mixture. This information was verified with the “PC Identify” computer software. We were able to identify the compounds and then determine each compound’s crystal structure, (hkl) values, lattice parameters and space group and compare the relative intensities of the experimental and theoretical data.

For the nickel oxide compound, the experimental relative intensities were very similar to the theoretical ones. However, for the potassium bromate compound, the experimental relative intensities varied greatly from the theoretical data. This may have resulted from either systematic or random errors. For example, a random error may have occurred in the counting statistics. This is the probability of the event occurring and is a measurement error. The scattering angle, theta, may not have been read properly. This is another example of a random error. The differences in relative intensity may also have been caused by a systematic error. For example, the scattering angle, theta, may not have been properly set to scale. Also, the mixture might have had a low “Z” value. In this case, the X-rays will just penetrate through the thin sample.

Summary:

The purpose of this lab was achieved. Two compounds in an unknown mixture were identified using powder diffraction techniques, scanning electron microscopy and the “PC Identify” computer software. The unknown mixture’s XRD powder pattern was downloaded from the computer and analyzed. Possible compounds in the mixture resulted from a peak search-match on the XRD powder pattern. The scanning electron microscope was used to examine the unknown mixture again and identify which elements were contained in it. Comparing the d-spacings, relative intensities and scattering angles from the XRD powder pattern to the PDF powder diffraction files helped identify the two compounds in the unknown mixture, along with the elemental analysis. It was determined that the two compounds in unknown mixture mx3 were potassium bromate (KBrO₃) and nickel oxide (NiO). These compounds were verified using the “PC Identify” software.

After identifying the compounds, we were able to determine each compound’s crystal structure, (hkl) values, lattice parameters and space group, and then compare the relative intensities of the experimental and theoretical data. The experimental relative intensities for the nickel oxide compound were very similar to the theoretical ones. However, for the potassium bromate compound, the experimental relative intensities varied greatly from the theoretical data, which may have been the effect of either the random or systematic errors described earlier.

Since the scanning electron microscope was not working Thursday October 13, 2005, we may want to retry part two on our own. This way we will be confident in using the SEM for future work.

Related:

• Extremophiles: varietals and adaptations