Media And Growth Of Bacteria

Media And Growth Of Bacteria To grow and reproduce, microorganisms require nutrients as their source of energy and certain environmental conditions. Adaptation to different habitats has been acquired by microbes living in the exposed environment. In the laboratory, however, these requirements are to be met by a culture medium. Therefore, media preparation is an essential aspect in microbial growth. There is a wide variety of media which can be used for laboratory purposes. Generally, similar procedures can be used in the preparation of media. In this practical, YT broth is prepared from yeast extract, trypton, NaCl and agar. YT broth is a commonly used bacterial Esherichia coli culture media in molecular biology. Usually, YT medium is applicable for phage DNA production. Compared to LB broth, YT is a richer medium in which it supports higher cell density and a longer growth period for E. coli. Bacteria are the most abundant and most important biological component as they involve in the transformation and mineralization of organic matter in the biosphere (Cho Adam, 1988; Pomeroy Wiebe, 2001). Generally, growth is defined as an increase in number of cells. Bacterial cell growth depends upon a large number of cellular reactions such as transforming energy. Syntheses of small molecules are performed to build macromolecules and to provide various cofactors and coenzymes for biochemical reactions. Polymerization of monomers builds the macromolecules in the bacterial cell. As the macromolecules accumulate in the cell, they are assembled into new structures with specific functions such as the cell wall, cytoplasmic membranes, ribosomes and flagella, if to name a few, and eventually lead to cell division. E. coli is used as a test organism in this practical for investigating the bacterial growth. Such a growing rod shaped cell bacterium elongates to approximately twice their original length and then forms a partition that constricts the cell into two daughter cells. This process is known as binary fission. A partition called the septum is formed by the inward growth of the cytoplasmic membrane and the cell wall from opposite directions. The septum continues to grow inwards until the two daughter cells are pinched off. When one cell separates from to form two daughter cells, one generation has occurred and the time required for binary fission is known as the generation time. Under the best nutritional conditions, the generation time of a laboratory E. coli culture is approximately 20 minutes (Buettner et al., 1973). The growth stages of bacterial cells are described in a growth curve consisting of the lag phase, exponential phase, stationary phase and death phase (Zwietering et al., 1990). In the lag phase, the bacterial cell begins to grow only after a period of time due to new environment being inoculated. The time interval of lag phase depends on the growth conditions and the history of the inoculum. If the growing culture is transferred into the same medium under the same conditions, there is no lag phase and exponential phase starts immediately. However, if the inoculum transferred is taken from the stationary phase in an old culture, lag phase is observed. This is because certain essentials of the cell have depleted and time is required for biosynthesis of new constituents. The lag phase is also observed when the cells are transferred from a rich culture medium to a poorer culture medium. In the poorer condition, the cells need to synthesize the essential metabolites that are not present i n the previous medium. Thus, time is needed by the cells to produce new enzymes. In the exponential phase, the cell divides to form two cells, both the total cell number and mass double but there is no change in the average cell mass. The cells are said to be in their healthiest state. The rate of exponential growth varies widely among microorganisms. The rate is influenced by environmental conditions and the genetic characteristics of the organism itself. In the stationary phase, the essential nutrients of the culture medium are used up and at the same time, the wastes produced by the bacterial cells accumulate in the culture medium. Thus, growth is inhibited. The exponential growth is ceased and the cells reach the stationary phase. There is no net increase or decrease in the cell number and hence the growth rate of the cells is zero. The cells enter the death phase of the growth cycle after reaching the stationary phase whereby cell lysis occurs. Figure 1: Typical growth curve of a bacterial population. The growth of E.coli is investigated under various cultural conditions, including effect of pH, temperature and aeration). Effect of pH is ascertained by preparing media of different pH values. Temperature is always a potentially limiting factor by affecting all chemical and biochemical processes and thus is viewed as an interactive factor (Pomeroy Wiebe, 2001). Aeration is done by shaking so that air space volume can be increased. As such, good and excellent aeration is stimulated. MATERIALS Media components (yeast extract, trypton, NaCl and agar), E. coli culture, 20x petri dish, 5250 ml conical flask and 1100 ml conical flask, plus cotton wool plugs in aluminium foil, Whatman paper METHOD Media Preparation The five 250 ml conical flasks and one 100 ml conical flasks were prepared and labelled as M1-M10 on the first day of practical. 100 ml of YT broth was prepared in 250 ml flasks, with the composition as trypton 1.6%(w:v), yeast extract 1%(w:v), and NaCl 0.5%(w:v). The pH was adjusted to those shown in table 2.1, followed by autoclaving. 500 ml agar was prepared in 1L flask, in which composed of YT broth and agar (13.5 g/L). The prepared medium was autoclaved. The agar was poured on 20 petri dishes. Inoculation Day 2 was begun with inoculating M1 to M8 with 1.0ml E. coli, while M9 and M10 as control set. Incubation was performed at 37Â °C for 24 hours. Whatman paper was dried overnight. Analysis Prior to an analysis, the culture was well shaken and the sampling was done under aseptic condition. Measurement of cell density and variable cell (as colony forming units, cfu) After the overnight incubation, a 3.0ml aliquot of each culture was taken and the absorbance was measured at 660nm. M9 and M10 was used as the blank. Data obtained was tabulated. Measurement of final pH of broth The final pH of the cell culture was measured. The results were also recorded in table 2.1. Measurement of CFU At day 3, a serial dilution was done from 10-2, 10-4, 10-6, 10-8 to 10-10. Hockey stick spreading technique was performed to plate out the sample. Two replicates were done for each plate, labelled a and b respectively. The culture was incubated at 37Â °C for 24 hours. The changes were observed and recorded on the next day, and thereby determining the CFU, as what recorded in table 2.2(a) and 2.2(b). Measurement of biomass The Whatman paper dried was weighed and the initial weight was recorded. A 10ml aliquot of the content of the flasks was filtered using the Whatman paper by washing with distilled water. The paper together with the content was dried in oven at 70Â °C overnight. On the next day, the final weight was measured and thereby obtaining the net weight gain of the filter paper. The result was recorded in table 2.3. RESULTS The pH change and the absorbance values measured were recorded in table 2.1. Flask M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 Pre-incubation pH 4.0 7.0 10.0 7.0 4.0 7.0 10.0 7.0 7.0 7.0 Post-incubation pH 3.96 7.08 10.16 7.16 4.13 7.21 9.93 7.73 7.12 7.14 OD660nm 0.108 1.267 0.01 0.916 0.191 1.906 0.056 1.812 0.0 0.0 Growth condition No shaking (with air space) No shaking (without air space) Shaking at 200 rpm (with air space) Shaking at 200 rpm (without air space) Table 2.1: pH change and absorbance measured for M1 to M10 CFU for plate labelled a and for plate b was calculated using the formula below, which was then recorded in table 2.2(a) and 2.2(b) respectively. CFU = colony number x dilution factor = x cfu/0.1ml = ? cfu/ml Table 2.2(a): CFU for plate labelled a Flask M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 Dilution (10-4) 55 22 0 >300 1 161 0 >300 0 0 CFU/ml 5500000 2200000 0 TMTC 100000 16100000 0 TMTC 0 0 Dilution (10-6) 0 13 0 185 0 24 0 3 0 0 CFU/ml 0 130000000 0 1850000000 0 240000000 0 30000000 0 0 Flask M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 Dilution (10-4) 13 >300 0 >300 0 >300 0 >300 0 0 CFU/ml 1300000 TMTC 0 TMTC 0 TMTC 0 TMTC 0 0 Dilution (10-6) 0 3 0 89 0 32 0 4 0 0 CFU/ml 0 30000000 0 890000000 0 320000000 0 40000000 0 0 Table 2.2(b): CFU for plate labelled b The biomass was calculated using the formula below and was recorded in table 2.3. Biomass (g/ml) = Flask M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 Initial weight of filter paper 1.14 1.16 1.14 1.17 1.19 1.15 1.16 1.19 1.16 1.17 Dried weight of filter paper 1.15 1.17 1.14 1.17 1.20 1.17 1.16 1.19 1.16 1.17 Mass Difference 0.01 0.01 0.0 0.0 0.01 0.02 0.0 0.0 0.0 0.0 Biomass (mg /ml) 0.001 0.001 0.0 0.0 0.001 0.002 0.0 0.0 0.0 0.0 Table 2.3: Biomass DISCUSSION From the tables in the result section and observation, we analyze the growth of E. coli under various pH and aeration condition. Measuring OD and calculating CFU give relevant and supportive information to our experiment. However, the biomass calculated is not applicable to accurately ascertain the factors affecting the growth as some errors occurred during the measurement of biomass, probably. Cell density and variable cell OD stands for optical density which indicates the wavelength of light. In this practical, OD660 measures the light absorbance by E. coli cultures, which correspond to the E. coli cell density in a given volume. OD660 determines whether the cells are ready for making cell stocks or as a competent cell. In other words, it can be said that in this part, OD660 was used to ascertain the quantity of E. coli grown in the YT broth after incubating overnight at 37Â °C. Flasks M1 to M8 were inoculated with 1.0 ml of E. coli culture. The result showed that growth had occurred. On the other hand, M9 and M10 served as the control set in which inoculation of bacteria was not applied, in addition to acting as blank during analysis with spectrophotometer. From table 2.1, it was shown that the OD of both M9 and M10 appeared to be zero. This shows that there was no sign of growth of E. coli in the two flasks. Spreading of plates was done in class II laminar flow cabinet. Sterile operation in cell culture is vital where it can affect the CFU of E. coli. This minimizes the chance of culture contamination. On top of that, the safety of the operator is ensured (Betler, 2004). From the aspect of CFU, as what shown in table 2.2(a) and 2.2(b), there was abundant of cells in M2, M4, M6 and M8. The cell density was still high even with the dilution of 10-6. Therefore, it was determined that E. coli has the optimum growth pH at 7.0. Effect of broths pH on growth Different growth condition gives different OD values. Optimum pH of E.coli growing in a culture at 37oC is around 7.0. E.coli is not able to tolerate under extremely alkaline and acidic environments because most of the enzymes found in the bacterium are very pH-sensitive. These enzymes carry out the important processes in E.coli. When there is extreme change in pH, enzymes in E.coli become denatured. Denature of enzymes in E.coli can lead to all sorts of interruptions to biochemical processes or even causes death of the E.coli. From table 2.1, it was found that there was no growth of E.coli in both flask M3 and M7 with pH 10.0; as the absorbance measured were 0.01 and 0.056 respectively. Whereas, there were some E.coli grow in flask M1 and M5 with pH 4.0, which have OD recorded 0.108 and 0.191 respectively. Thus, it can be concluded that E.coli seems to be more tolerate to lower pH (acidic condition) than higher pH (alkaline condition). Since pH 7.0 is the optimum pH for the growth of E.coli at 37oC, there were many colony of E.coli growing on the agar plates which spread with the sample from flask M2, M4, M6 and M8. There are some changes in the pH before and after the incubation. This is because there is formation of inhibitory products such as organic acids during the growth of E.coli in the YT nutrient broth. Effect of aeration on growth pH of medium is determined by medium composition, buffers, cellular metabolism and aeration. NaCl is used as buffer, where the depletion of this organic buffer will cause an E. coli reaches its maximum pH limit. Hence, care has to be taken to balance the organic buffer, sugar content and aeration medium because low aeration leads to production of acids; High aeration causes cells to use organic acids as carbon source, and thus increases the pH of medium. In brief, selected aeration also helps in maintaining cells pH. Theoretically, shake flask incubator reduces the solid and liquid inter-phase, thus minimizing the mass transfer. Increased speed and momentum cause cells to lyse among themselves. Increased speed also increases the formation of foam, thus trapping gas and resulting less gas in the liquid. Since cells require nutrients for survival, absence of gas as nutrient source will cause cells to die. Hence, shaking flask actually plays an important role in bringing an improvement to mass transfer between the gas phase outside the shake flask and the liquid phase inside the shake flask. Shake flask incubator can provide a suitable environment by ensuring sufficient transfer of oxygen gas to the cell culture by appropriate mixing. Agitation will increase the aeration of the bacterial growth of E.coli. This is because oxygen is important for high density growth of E.coli cells. Agitation is controlled by the shaking speed of a shaker incubator. Thus, from the observation, Whatman paper with content from M6 has bigger biomass than others. The biomass of M6 is 1.0 mg/ml. This is because flask M6 has been shaken at 200rpm and the flask contains air space which helps in the growth of E.coli cells. Therefore, the media without shaking or without air space or without both of these growth conditions has less growth of E.coli. Thus, M6 has the best growth condition for E.coli if compared with other media. However, from the observation in this experiment, there is more E.coli colony grows in M8 (growth condition with shaking at 200rpm but without air space) than M6 (growth condition with both shaking at 200rpm and with air space) in the culture with serial dilution 10-4. Theoretically, there should be less E.coli colony grows on the plate which spread with the culture from M8 since flask M8 has less flavour growth condition for the growth of E.coli. This unexpected observation may be because the sample with serial dilution 10-4 is not well shaken before take 1.0ml of aliquot to spread on the plate. From our result, it was again determined that the growth rate of E. coli is not affected by shaking. This is proven through our experiment where there was no significant difference in yields with or without shaking cultures. When air is supplied, however, shaking cultures shows a higher yield than static cultures. The main purpose of shaking cultures at 20 rpm is to mix thoroughly the nutrient concentration in broth, with constant temperature, 37Â °C. 37Â °C is the optimum growth temperature for E.coli. Shaking prevents cells localizing at the bottom of the broth which causes a faster depletion of nutrient as time passes. Nutrients still present in the broth but cells may not accessible to them. Hence, shaking minimizes areas of high and low nutrient concentration. The amplitude of the vibration controls the intensity of fluid mixing. Shaking broth brings advantage to non-motile cells because it enables the metabolism rate to continue, in addition to benefiting mobile cells by redu cing energy on mobility. Besides, shaking increases the aeration of broth which leads to a higher yield of E. coli. From the OD values, OD at pH 7 shows the highest value for both shaking and non-shaking media because pH 7 is the most suitable medium for growth of E.coli. However, pH 7 from shaking broth has a comparatively higher OD reading compare to non-shaking broth due to shaking enhances the growth of E.coli. However, OD of pH 4 is far higher than OD of pH 10 because E.coli can still grow on pH 4, but pH 10 does not really support growth of E.coli. As for M9 and M10, both broths do not show any OD reading value because no E.coli culture is added into both broths. When pH and vibration are held constant (i.e. pH 7 with shaking), broth with aeration shows a higher OD value compare to non-aeration. This means that a higher E.coli cell density in aerated broth compare to non-aerated broth. When other factors are held constant, air space does not significantly affect E.coli yields, because E.coli is a facultative anaerobe, which means E.coli is able to produce energy during aerobic respiration and switch to anaerobic respiration when oxygen is depleting in the environment. Thus, E.coli grows in both with or without air space broth. Supposedly, colony forming unit (CFU) in plates from medium with air space has a higher growth amount compare to medium with no air-space. This is because E.coli cells produce a large quantity of acetic acid with no air-space, and thus reducing the pH of broth and does not favour the growth of E.coli. Acetic acid inhibits growth condition under anaerobic growth condition. However, according to our result, when the pH and vibration are held constant (both of pH 7 and with no shaking), CFU is greater in non air space compare to with air space. This may be due to errors occur where the mouth of broth is not tightly covered which leads to entranc e of oxygen molecules into the broth. CONCLUSION Sterile medium such as sterile YT broth is essential for bacteria growth. The optimum pH for the growth of E. coli is 7.0. Excellent aeration promotes growth of bacteria to a further extent than what good aeration does. QUESTIONS Write a flow chart for the above protocol before you start work. Label all the conical flasks from M1 to M10 Add 100ml YT broth to flasks M1 to M3 and M5 to M7 Adjust the pH of the media to 4.0,7.0 and 10.0 using either HCL or NaOH Autoclave and allow to cool to room temperature For flask M4 to M8, autoclave 200ml of the medium in a bigger container and then pour the cooled medium into the sterile 100ml conical flask Inoculate flasks M1 to M8 with 1.0ml of E.coli culture under aseptic conditions Incubate with or without shaking as indicated from the table Prepare M9 and M10 under the same conditions as for flask M2 and M6, but do not add any inoculum Prepare and autoclave the agar After an overnight incubation,take 3.0ml aliquot of each culture and measure the absorbance at 660nm Do a serial dilution from 10-1 to 10-5 in a sterile microfuge tube and plate out 0.1ml of the sample at 10-4 to 10-5 in YT agar media Incubate at 370C overnight Determine the cfu/ml of the original culture and tabulate data Measure the final pH of the cell culture and tabulate results Filter 10ml aliquot of the content of the flasks using pre-weighted Whatman paper dried in an oven at 800C overnight Measure the net weight gain of the filter paper as an indication of biomass Tabulate results Discuss your results with respect to the effect of pH of the media and aeration on bacterial growth and reasons for your observations. In addition to nutrients, the pH of the growth medium is also important for E.coli growth rate and cell density. The optimal growth pH for E.coli is near neutral. E.coli cells can grow reasonably well over a range of three pH units (from pH 5.5 to 8.5). Extreme pH beyond this range will significantly decrease the cell growth rate and may sometimes even cause cell death. The minimum and maximum growth pHs for E.coli are pH 4.4 and 9.0 respectively. E.coli cells appear to tolerate a more neutral pH better than a high pH. This is clearly shown as E.coli grows well at pH 7 as shown on plate M2, M4,M6, and M8.In fact, extended exposure of E.coli cells to a high pH causes cell lysis. This is the reason why no colonies were found on plate M3 and M7. At the saturation or stationary phase, the pH of the E.coli culture in commonly used media is near its pH limits. pH is another limiting factor for cell growth in addition to nutrition exhaustion and accumulation of toxic metabolites. E.coli cel ls can also use sugars such as glycerol and glucose as carbon or energy sources. When the E.coli cells use these sugars as carbon sources, they will produce acetic acid and therefore lower the medium pH. Carefully balancing the sugar contents, and aeration conditions can maintain the culture medium pH near E.coli optimum growth pH or within the range of the three pH units. Low aeration conditions lead the cells to produce acids. High aeration conditions allow the cells to use organic acids as carbon source and increase medium pH. Selected aeration conditions can also help cells maintain its medium pH. Do your data on absorbance at 660nm correlate with the cfu/ml and biomass data? Explain. The data on the absorbance at 660nm correlates with cfu/ml as a lower OD660nm gives a high cfu/ml and vice versa. But the data of absorbance does not correlate with the biomass. Despite the inherent inaccuracy of the method, if the procedure is adequately controlled and calibrated the estimation of microbial numbers by optical density should be sufficiently accurate for use in preparing inoculum for cfu/ml testing. Would you expect to obtain the same data if you were to scale up the experiment using a 1000L fermenter? Explain your answer. No, as the size and volume of the fermentor increases, the volume and density of the E.coli culture will increase too so the CFU/ml will also increase.

Flight 587 Crash Investigation

This paper examines the disaster of American Airlines flight 587 on November 12, 2001 in New York City. At least 265 people died in this tragedy making its one of the major disasters in modern aviation history. In the immediate aftermath of the accident, there were great fears that this could be another outcome of a terrorist attack on the U. S soil. Official investigations, however, quickly ruled out any terrorist involvement. Findings indicated that the weak wake turbulence caused by an airplane that took off slightly before flight 587 initiated an unfortunate chain of events that resulted in the catastrophe.The final report of the NTSB held the faulty rudder control system design of Airbus A300-600, and the inadequate pilot training program of American Airlines to be chiefly responsible. In addition, the allegedly quirky response behavior of the first officer at the controls of the airplane is considered a critical factor. However, many people, common men and experts alike, are no t convinced of the validity of the NTSB investigations. Introduction On the morning of November 12, 2001, Tom Lynch, a retired firefighter, is on Rockaway Beach Boulevard taking his regular morning exercise march.He watches an airplane complete a banked turn and start towards the ocean. Then, all of a sudden, he sees a small explosion in the fuselage behind the wing. Two more seconds elapse and suddenly there is a second explosion, engulfing most of the plane in flames. It was the American Airlines Flight 587. Two months after 9/11 – this Airbus 300-600 left John F. Kennedy International Airport en route to Santa Domingo, the Dominican Republic. Less than three minutes after takeoff, the aircraft crashed in a blazing inferno in the heart of the neighborhood of Bell Harbor, Queens. All 251 passengers along with 9 crew members perished.Most remarkably, only five people died on the ground. 44 fire trucks and 200 firefighters were rushed to the scene. Soon, the disaster of AA Fli ght 587 would be found not to be due to terrorism, but to mechanical failure. However, in the stark post 9/11 environment of the day, it was difficult for many people to believe that planes could still fall from the sky for reasons unrelated to terrorism. Feelings and fears were especially strong and these were exacerbated this fresh tragic event. As the author S. D. Manning (2003) put it, â€Å"This crash jarred a city (and a nation) still scarred and numb from the agony it has already endured†The Investigation Tonight, American holds its collective breath, Prays this nightmare is due to mechanical failure, Not premeditated design. The sheer irony would shame Kafka – It's not the disaster itself but its cause That bothers us, enslaves us to out TV's; We pray that it’s something man-made, not man. – L. D. Brodsky. (2002). As the aircraft climbed from John F. Kennedy airport, some people on the ground saw an explosion and fire on the underneath side of the aircraft, which was quickly followed by parts falling off the aircraft, including the vertical stabilizer and rudder.During the aircraft's fall, engines came away from the wings. Falling separately, one engine landed on Beach 129th Street the other engine on Beach 126th. The plane then plunged to the ground on the narrow strip of land known as Rockaway, in Belle Harbor at Queens. The plane's tail broke off and fell into Jamaica Bay, more than a mile from the primary crash site. Although a few stray remnants landed here and there, the fuselage and wings pounded into the home on the corner of Beach 131st Street and Newport Avenue. The plane's impact, subsequent explosions, and fire destroyed other homes.The rudder and the tail fin were found first along the flight path, followed by the engines and then the main wreckage. According to the NTSB, the tail fin and rudder of the plane sheared off as it accelerated. The aircraft began a climbing turn over Jamaica Bay when it encountered tu rbulence caused by the wake vortices generated by a Japan Airlines 747 that had taken off just one minute forty-five seconds earlier. Records from the flight data recorder later recovered from the crash site showed that the turbulence had cause movements of flight 587's rudder, part of which, together with the vertical tail fin, became detached from the aircraft.Control of the aircraft was lost and it fell from the sky. This was the second deadliest crash in US history, but it also, â€Å"was the first example where we had an in-flight failure of a major structural component of an aircraft that in fact was made of composite materials,† as NTSB Chairwoman Marion Blakley would assert later. From the outset, the investigation into the loss of the American Airlines aircraft was conducted on the premise that it was an accident. There seemed to be no immediate indication it was anything else, except for the numerous eyewitness accounts of fire and explosion just before the aircraft plummeted.Officials were keen to reiterate that there was nothing to suggest any foul play had been involved in the loss of the aircraft. Coming so soon after the September 11th outrages, another terrorist assault in America would have been untenable and morally damaging. The President had declared war on terrorism. Congress had been actively involved in developing new legislation to contain the threat that al-Qaeda posed to civil aviation operations. The possibility of a terrorist strike seemed a little farfetched in the state of intensely heightened vigilance that the air transportation industry was in during the aftermath of 9/11.Even if there was foul play involved, it could have been more of a sabotage than the explosion of a bomb. Though terrorism was suspected by everyone, it could not be substantiated. The main difficulty of associating the loss of AA587 with terrorism was the manner of its destruction. If the tail assembly did lie at the root of the problem, then sabotage when the aircraft was on the ground appeared a more likely scenario than a suitcase bomb or a suicidal passenger detonating a device on board the plane. Accident scenarios had to be explored first.Marion Blakley said in an interview on CNN Newsnight on the day of the crash: One of the things that we're very committed to doing is to have a full investigation from a system standpoint, mechanical standpoint, looking at the history of this flight, the crew, the human factors that may have been involved. Immediately following the loss of flight 587, a 40-strong NTSB Go Team under the Investigator-in-Charge Robert Benzon was sent to the site of the crash (NTSB News, 2001). As was the norm, their work was supported by other agencies and companies considered appropriate by the board.The NTSB used the American Airlines facility at Tulsa for a detailed examination of the aircraft engines. No evidence was found of a fire, bird strike, or other pre-impact malfunction. The auxiliary power unit ( used to power the aircraft when it is on the ground) was sent to Honeywell, its manufacturer. Nothing wrong was found with the unit. The tail fin and rudder assemblies underwent visual inspection in New York before being sent to the NASA Langley Research Center in Hampton, Virginia.Extensive preliminary tests at Langley sought to identify whether the vertical stabilizer and rudder had had any damage or faults before the accident. None were found. Although the flight data recorder indicated significant rudder movement before the crash, there was nothing to show why this had happened (NTSB News 2002). That both engines separated from the wings as the aircraft fell from a comparatively low height posed another question: Could the engines have been sabotaged, if not by an explosive device, then by some other means so far undetected by the NTSB investigators?â€Å"Investigators suspect a catastrophic engine event as the likely cause of an airline crash Monday in New York,† went CN N. com’s headline on the very day of the accident. However, the primary focus of the investigation eventually shifted to the rudder system. The NTSB team flew to France to work with experts from Airbus Industrie, the aircraft's manufacturer, at their headquarters in Toulouse. The purpose of this visit was to study at firsthand the mechanism of the rudder system and to simulate the pattern of the aerodynamic loads that may have affected the vertical stabilizer during the failure of flight 587.If the investigators could not identify a possible mechanical or structural reason for the accident, they would have been left considering the impossible. Even though they may not have found any terrorist involvement in the loss of AA flight 587, in the absence any other demonstrable reason for the crash, terrorism would be back in focus. Flight History Flight 587 was an Airbus A300-600, Registration Number N14053. It took off from JFK International Airport at 9:14:29 A. M. on November 12 , 2001 in clear weather conditions. At 0915:44.7, the captain Edward States asked, â€Å"little wake turbulence, huh? † to which the first Officer, Sten Molin, replied, at 0915:45. 6, â€Å"yeah. † At 9:15:51, when the plane was 2,000 feet and was over Jamaica Bay, the first officer initiated a series of emergency control inputs and called for the emergency â€Å"escape† maneuver. During the wake turbulence encounter, the airplane’s pitch angle increased from 9? to 11. 5? , decreased to about 10? , and increased again to 11?. At 9:16:01. 9, F. O. Molin was heard on ATC uttering â€Å"losing control.†The airplane crashed 13 seconds later, it was airborne for less than 106 seconds. At 0915:58. 5, the CVR (Cockpit Voice Recorder) recorded the sound of a loud bang. At that time, the airplane was traveling at an airspeed of about 251 knots. â€Å"Hang onto it, Hang onto it,† were the last words of the Captain Edward States, as recorded on the CVR The Crew Background The captain was 42 years of age and the first officer 34. They were hired by American Airlines in July 1985, and March 1991 respectively. The captain had 1,922 hours total flyingtime in military and general aviation before his employment with American Airlines, and 8,050 hours total flying time thereafter which included 3,448 hours as pilot-in-command and 1,723 hours as a pilot-in-command for A300 specifically. His last proficiency check took place on June 21, 2001; and his last pilot-in-command line check occurred on July 31, 2001. He consumed alcohol sparingly and never during a time around his work schedule. According to a colleague, he was an extremely good pilot, very relaxed and competent.The first officer had 3,220 hours total flying time in commercial and general aviation before his employment with American Airlines, and 4,403 hours total flying time, which included 1,835 hours as second-in-command for A300 specifically. Both the captain and the first of ficer had no FAA records that indicated any incident history or enforcement action. One pilot who worked with the first officer, however, described him as being â€Å"very aggressive† on the rudder pedals after a wake turbulence encounter. Except for that, his overall skills were described as excellent, and â€Å"well above the norm. †The 5M ConceptThe 5M concept is a risk assessment tool used to graphically illustrate how the dynamic interaction of the man, the machine and the media (that is, environment) converge to produce either a successful mission or if unsuccessful, a mishap. Man-category encompasses aircrew members, their training, selection, proficiency, habit patterns, performance, and personal factors. Factors under â€Å"performance† heading include awareness, perceptions, saturation, distraction, channelized attention, stress, confidence, adaptive skills, and fatigue (physical, motivational, sleep deprivation, circadian rhythm, klutz).â€Å"Persona l factors† include job satisfaction, values, families/friends, command/control, discipline (internal and external), and communication skills. The Machine-category encompasses the various design, maintenance, logistics, and other technical data related to the aircraft. The Media is the environment in which aircrew fly and includes factors and forces that are related to climactic, operational, hygienic conditions. The fourth category is the management. Management regulates standards, procedures, and controls.The interaction between the 4M’s Man, Media, Machine, and Management determine the desired outcome, or the Mission. When outcome fails to meet anticipated goals, these 5 M’s must be thoroughly reassessed (Civil Air Patrol). The Shell Model The factors that affect the outcome of each flight can be assessed under the SHELL Model: Software, Hardware, Environment, Liveware (outer ring) and Liveware (inner ring). Software is what makes the system work, and includes guidelines, regulations, operation specifications, and company policy and procedures.Hardware is the physical equipment that is necessary for a flight to operate. The category â€Å"Environment† relates to the broad external context that can affect the flight or the pilot, and includes factors such as weather, g-forces, and ambient light. Liveware represents the human factors. The outer ring includes air traffic controllers, flight service briefers, dispatchers, other crewmembers, pilots of other aircraft, flight attendants.The inner ring is the most important part of the SHELL model and includes various variables affecting the competence and performance of the pilots (Shields 2002). The NTSB Findings The NTSB officials very early on in the investigation suggested the cause of the crash might be due to wake turbulence from an aircraft that departed earlier. However, many experts doubted that the light turbulence from such an encounter would register on the scale of the type o f extreme turbulence that aircraft undergo from atmospheric disturbances such as in the vicinity of thunderstorms.Commercial jets are built to withstand forces up to 2. 5 G-forces, while the turbulence that hit the plane was one tenth of a G-force — barely strong enough to be even noticed (Dyer 2002). The Board then suggested that the composite vertical stabilizer may be faulty. However, this does not address the numerous reports of reliable witnesses, such as policemen and firemen, concerning fire and explosions coming from the aircraft before the vertical stabilizer ripped from the aircraft.Finally, after three years of investigations, National Transportation and Safety Board stood by its wake turbulence hypothesis. However, it was only a triggering event. The report, under the heading â€Å"Probable Cause† placed most of the blame on the first office for his â€Å"unnecessary and excessive rudder pedal inputs. † It goes on to say, â€Å"Contributing to these rudder pedal inputs were characteristics of the Airbus A300-600 rudder system design and elements of the American Airlines Advanced Aircraft Maneuvering Program† (NTSB 2004).The NTSB's conclusion was that the cause of the crash was the tail separating from the fuselage, which happened as a result of pilot placing loads on the tail that exceeded its ultimate limit – which in turn was an outcome of pilot’s rudder movements. He put excessive pressure on the rudder pedal in response to the wake turbulence caused by the JAL flight that preceded them. But why did the pilot move the rudder pedals as aggressively as he did? This became an issue of great controversy.The NTSB report dwells on the previously observed tendency of the first officer to place inappropriate pedal inputs, which in tandem with two other reasons, the deficient pilot training system and the defective Airbus rudder control system, resulted in a colossal disaster: The Safety Board’s investigat ion determined that three main factors influenced the first officer’s rudder use during the accident sequence: a tendency to react aggressively to wake turbulence, as evidenced by his responses to previous wake turbulence encounters; his pilot training, including the training he received at American Airlines regarding wake turbulence, upset recovery, and rudder pedal use; and the characteristics of the A300-600 rudder control system. (NTSB 2004)These findings resulted in a mammoth row between Airbus and American Airlines is –– with Airbus contending that the first officer’s inappropriate response caused because of his improper training by American Airlines, and the American Airlines contending the Airbus’ rudder pedal system unusually sensitive.The NTSB RecommendationsThe NTSB report discusses several safety issues relevant to the Flight 587 disaster, focusing on characteristics of the A300-600 rudder control system design, A300-600 rudder pedal in puts at high airspeeds, aircraft-pilot coupling, flight operations at or below an airplane’s design maneuvering speed, and upset recovery training programs. Airbus Industrie and American Airlines have acted upon industry-wide amendments to ensure safety of operation of aircraft.American Airlines continue to operate the Airbus A300, Airbus are confident of the structural and functional integrity of their plane – although many AA pilots and those of other airlines sought transfer to supposedly much more stable Boeing airplanes in the wake of the disaster. Conclusion New Yorkers may be resilient, But they have their breaking points, And they must be getting close to them. Like all of us, they want to believe That something like a shorting wire, Exploding fuel tank, or malfunctioning turbofan Is the reason at least 265 perished in Queens. – L. D. Brodsky. (2002).The biggest unresolved issue in this entire tragic episode of Flight 587 crash were the flames and the ex plosions noted by over 50% of over 400 witnesses. In its report, the NTSB attributes them to either an â€Å"initial release of fuel† or the â€Å"effects of engine compressor surges. † Both of them could have been caused due to out-of-control motion during the airplane's precipitous descent. However, one must remember that the airplane had just took over and was not at a great height, and most importantly that the witnesses observed the fire before anything else happened.In effect, the fire could not have been set off during the descent and as a result of the descent. Most of the witnesses are unequivocal about it and stand vehemently by their testimony to this day. Many quarters have felt that the NTSB prematurely declared the crash to be an accident and hastily concluded that the tail separation was the initiating event without adequate analysis of all the evidence, and especially without giving proper credence to witness testimony – and later went on to bols ter its convenient preconceived notions.Today, claims of NTSB cover-up and conspiracy theories pointing to terrorist involvement abound around this subject – making the tragedy of flight 587 a lingering mystery.References:Brodsky, L. D. (2002). Shadow War: A Poetic Chronicle of September 11 and Beyond, Volume Two. St. Louis, Missouri : Time Being Books Civil Air Patrol. Civil Air Patrol Guide to Operational Risk Management. Retrieved 3 March 2007 from www. orwg. cap. gov/Safety/CAPguidetoORM. pdf Dyer, N. (2002). The Mystery of Flight 587?What Caused the Crash of Flight 587? Science World. Feb 25 2002. Retrieved 3 March 2007 from http://www. findarticles. com/p/articles/mi_m1590/is_10_58/ai_83667600Manning, S. D. (2004). American Dream, A Search for Justice. New York : A&M Publishing NTSB News (2001).American Airlines Flight 587. National Transportation and Safety Board. 12 November 2001. Retrieved 3 March 2007 from http://www. ntsb. gov/events/2001/AA587/default. htm   NTS B News. (2002).Fourth Update on NTSB Investigation into Crash of American Airlines Flight 587. National Transportation and Safety Board. January 15, 2002. Retrieved 3 March 2007 from http://www. ntsb. gov/Pressrel/2002/020115. htm NTSB. (2004).Aircraft Accident Report. National Transportation and Safety Board. October 26, 2004. Retrieved 3 March 2007 from http://www. ntsb. gov/publictn/2004/AAR0404. pdf Shields. J. (2002).SHELL Model. Josh's Little Aviation Place on the Web. Retrieved 3 March 2007 from http://people. aero. und. edu/~jshields/CRM/shell_model. htm

The Unusual Details About Essay Intro for 5th Grade Samples Most People Arent Aware Of

The Unusual Details About Essay Intro for 5th Grade Samples Most People Aren't Aware Of The Basic Principles of Essay Intro for 5th Grade Samples You Can Learn From Beginning Immediately You might think that this is a really long process only for developing the ideas which you will present. Any examples or support you provide ought to be about the topic accessible. Make certain to have permission from every parent before beginning any form of camera undertaking. Look at these sites for ideas. 10-11 year-old 5th graders are predicted in order to organize their ideas and structure sentences well. Write about a day you want to forget. Describe the ideal day. Write about your day in the life span of that individual. The Fight Against Essay Intro for 5th Grade Samples Whatever you should finish your writing and receive an exemplary grade, you can get it right here. Do not be concerned, EssayPro is here in order to teach our students everything they will need to learn about c rafting an informative essay! Students need to understand how to compose persuasive essaysthis skill is critical since it's often tested. 1 approach to get students energized to review math is to make math partners that work with each other to solve what you've assigned them. Math worksheets for 5th graders comprise math problems on several different topics and provide the kids a chance to brush up on their math abilities. Some individuals wouldn't be able accept that the subject Math is straightforward. If you're feeling confident about your essay-writing abilities, you can definitely branch out into longer and more intricate essays. To get ready for the demands of middle school and higher school writing, fifth graders ought to be mastering skills necessary for strong nonfiction writing. As always, The Teacher's Corner is searching for strategies to create your life simpler. Imagine your teacher is really your parent. If you would rather, you may ask the student to simplify. Students learn how to write effectively when they write more frequently. Who Else Wants to Learn About Essay Intro for 5th Grade Samples? Students should be in a position to share their ideas with proper and efficient word choice and use a selection of different sentence structures. Fifth grade students utilize every phase of the writing procedure and continue to construct their understanding of writing conventions. In any event, you can choose from what angle that you want to approach the topic. The very first sentence is regarded as the opener as it introduces the topic and grabs the reader's interest. For instance, you can create a mind map by means of your thesis idea or even the entire thesis sentence in the center. Likewise, it has to be logically complete and express a particular idea. Top Essay Intro for 5th Grade Samples Secrets This worksheet types are past the Common Core standards. Based on what standard you're working on, or wish to review, can guide your bag activity. A target point is the area of the thesis that you're aiming to prove. Thus, it's the very best choice to purchase from the stores immediately. The Essay Intro for 5th Grade Samples Game This paragraph is just one of the most crucial in our papers. These sentences express a few principal ideas that support the opinion in the very first sentence. Students are requested to indicate how a specific sentence may be corrected or improved or the way the organization or development of a paragraph may be strengthened. Inside this paragraph, the very first sentence should transition from the prior paragraph to the current one. The subsequent 5 paragraph essay template should inform you precisely what you should do to finish your assignment. After introducing your topic sentence, it's time to stick to the CCE format to craft the most crucial region of the essay. The thesis statement is the principal idea of the essay and it expresses what you would like to tell the reader in a couple of sentences. To be able to effectively complete the essay, an individual must develop an overall concluding statement.

What Is the Definition of Role Conflict

Role conflict happens when there are contradictions between different roles that a person takes on or plays in their everyday life. In some cases, the conflict is a result of opposing obligations which results in a conflict of interest, in others, when a person has roles that have different statuses, and it also occurs when people disagree about what the responsibilities for a particular role should be, whether in the personal or professional realms. To truly understand role conflict, though, one must first have a solid grasp of how sociologists understand roles, generally speaking. The Concept of Roles in Sociology Sociologists use the term role (as do others outside of the field) to describe a set of expected behaviors and obligations a person has based on his or her position in life and relative to others. All of us have multiple roles and responsibilities in our lives, that run the gamut from son or daughter, sister or brother, mother or father, spouse or partner, to friend, and professional and community ones too. Within sociology, role theory was developed by American sociologist Talcott Parsons through his work on social systems, along with German sociologist Ralf Dahrendorf, and by Erving Goffman, with his numerous studies and theories focused on how social life resembles theatrical performance. Role theory was a particularly prominent paradigm used to understand social behavior during the middle of the 20th century. Roles not only lay out a blueprint to guide behavior, but they also delineate the goals to pursue, tasks to carry out, and how to perform for a particular scenario. Role theory posits that a large proportion of our outward day-to-day social behavior and interaction is defined by people carrying out their roles, just like actors do in the theater. Sociologists believe that role theory can predict behavior; if we understand the expectations for a particular role (such as father, baseball player, teacher), we can predict a large portion of the behavior of people in those roles. Roles not only guide behavior, but they also influence our beliefs as the theory holds that people will change their attitudes to be in line with their roles. Role theory also posits that changing behavior requires changing roles. Types of Role Conflict and Examples Because we all play multiple roles in our lives, all of us have or will experience one or more types of role conflict at least once. In some cases, we may take on different roles that are not compatible and conflict ensues because of this. When we have opposing obligations in different roles, it may be difficult to satisfy either responsibility in an effective way. Role conflict can occur, for example, when a parent coaches a baseball team that includes that parents son. The role of the parent can conflict with the role of the coach who needs to be objective when determining the positions and batting lineup, for example, along with the need to interact with all the children equally.  Another role conflict can arise if the parents career impacts the time he can commit to coaching as well as parenting. Role conflict can happen in other ways too. When the roles have two different statuses, the result is called status strain. For example, people of color in the U.S. who have high-status professional roles often experience status strain because while they might enjoy prestige and respect in their profession, they are likely to experience the degradation and disrespect of racism in their everyday lives. When conflicting roles both have the same status, role strain results.  This happens when a person who needs to fulfill a certain role is strained because of obligations or extensive demands on energy, time or resources caused by the multiple roles. For example, consider a single parent who has to work full-time, provide child care, manage and organize the home, help kids with homework, take care of their health, and provide effective parenting. A parents role can be tested by the need to fulfill all of these demands simultaneously and effectively. Role conflict can also ensue when people disagree about what the expectations are for a particular role or when someone has trouble fulfilling the expectations of a role because their duties are difficult, unclear or unpleasant. In the 21st century, many women who have professional careers experience role conflict when expectations for what it means to be a good wife or good mother — both external and internal — conflict with the goals and responsibilities she may have in her professional life. A sign that gender roles remain fairly stereotypical in todays world of heterosexual relationships, men who are professionals and fathers rarely experience this type of role conflict. Updated by Nicki Lisa Cole, Ph.D.