Critique of quantitative methods journal paper

 

 

 

 

 

 

Critique of quantitative methods journal paper

University affiliation

 

 

 

 

 

 

 

 

 

 

 

Introduction

Contribution and Gaps                                       

Dong, Seo and Bartol in their research paper are trying to explain the contributions of developmental job experience in training employees to improve their learning. They argued that shortage of large pool of well trained workforce and high cost incurred by companies hiring external experts has compelled many firms all over the world to utilize development assignments aimed to facilitate employees on job training and learning. Adoption of developmental job experience by company’s helps the employees in career advancement and it instills the needed confidence to the employees preparing them to hold high job levels. Through such program the company creates a large stock of human capital thus reducing the costs incurred by the firms in recruiting, selecting and engaging external new recruits to fill the vacant managerial positions.

They researchers argued that highly challenging DJE can bring the unintended negative consequences. Some development assignments were found to bring in stress related emotions which increased an employee’s intentions to seek job elsewhere to avoid the strain associated by his or her current job.  The researchers argued that few scholars had explored whether and how developmental job experience could produce both positive and negative results. The researchers found that majority of the earlier researches linking Developmental job experience to personal outcomes had used cognitive approach. The researchers found a gap existed:

“…..few scholars have investigated whether and how DJE can produce both positive and negative consequences, such as advancement potential and turnover intention, simultaneously within individuals” (Dong,seo & Bartol, 2014)

Aims of the Research

The research was aimed to examine to what extend was Developmental job experience associated with employees career advancement and turnover intention and the reasons why it might also fail in that regard.

Transactional stress Theory

Evaluation of the Transactional stress theory

According to Lazarus and Forkman transactional stress theory argues that, when an employee is faced with a stressor, the individual evaluates the potential threat and comes up actual strategy to mediate both its two levels of coping efforts and the actual outcomes of the response. “Stress is not a property of an individual, or a property of the environment, but it arises when there is a stimulator between the particular kind of the environment and particular kind of person that leads to a threat appraisal” (Lazarus, 1991c). “Interaction of a person and his or her environment can create ambiguous danger or threat”,(Smith, C. and Lazarus, R. S, 1990).while According to (Selye.H, 1983) , “stress is due to both negatively and positively toned experience that he said could be contributed to and  moderated by cognitive factor”. The model proposes that if an individual has a stake in the encounter should engage in the secondary appraisal in order to try to tackle the conditions perceived to be undesirable.

Previous use of the transactional stress theory

According to transactional stress model coping to the stress is affected by the choice of the coping efforts made by the affected employee. “Coping is expected to be consistent with a determination of whether anything can be done to change the situation”, (Folkman, S. and Lazarus, R. S., 1985) . Primary and secondary appraisals are central to Lazarus cognitive theory of stress. The person can choose the Primary appraisal which is considered as an evaluation stage to the significance of the encounter or transaction to the person. If the individual finds that he/she a stake in the encounter, the model proposes that the individual should go for the secondary appraisal in order to try to tackle the conditions perceived to be undesirable to him or her.

Use of the Transactional Stress Theory in the Study

The authors used the transactional model in their study to point to the possibility that stressful job demand and threats in a workplace can lead to both positive and negative feelings and how the individuals reacts to  stress fulsituations. The authors tried to examine if these feelings can affect the effectiveness of the employees. The authors also examine how the developmental job experience can lead to employee’s advancement potential and turn over intentions. The authors argued that past researches had focused mainly on individuals cognitive and passionate characteristics and missed to elaborate how employee’s affective characteristic influences patterns of affective processes between developmental job experience and work results. In their work, they examined the how DJE theory is linked to two opposite work outcomes: potential advancement and turnover intentions. Contrasting the previous use of the theory, which was cognitive in approach, the researchers incorporated and established the negative and positive influence of DJE on varied affective experiences. In conclusion, the researchers examined how DJE was related to both pleasant and unpleasant feelings to the employees’ advancement potential and turnover intentions.

Quantitative Methods and Analysis

Hypothesis

The first two hypotheses used by the authors related to transaction stress theory and explain the pleasant and unpleasant feelings experience in developmental job assignments and their relation to the advancement potential. The third hypotheses are relating pleasant feeling to advancement potential and also pleasant feelings is said to mediate the relationship between developmental job experience and advancement potential. Fourth hypotheses are related to negative or unpleasant feelings where unpleasant feelings are negatively related to advancement potential and are also a mediator between DJE band potential advancement. In this case DJE is indirectly related to advancement potential. In Fifth hypothesis pleasant feelings is associated to low turnover while in 6th hypothesis unpleasant feelings is directly related to turnover intentions and is a mediator between DJE and turnover intention relationships. In this 6bth hypothesis DJE is positively and indirectly related to turnover intentions through unpleasant feelings.

The last four hypothesesrelate job outcomes to emotional intelligence. The seventh hypothesis relates emotional intelligence with Developmental Job Experiences and affective experiences. Eighth, ninth and tenth hypotheses authors explains the relationships among emotional intelligence, advancement potential and turnover intention.

Study Design and Sample

In their test model, the authors study sample consisted of 357 part time career managers doing their masters business program from the university of Mid Atlantic in United States. They considered such sample because individuals in management positions were thought to have likelihood to obtain DJE in varying degrees. Experience sampling procedure was employed to access participant’s effective experiences. The procedure was relevant to their study because independent variables were to be examined to establish their effect on the effective experiences. Out of the 357 participants, 214 participants completed all the three surveys. Due to the high response the bias was minimal.

Measures – Independent, Dependent, and Control Variables

Developmental challenge profile(DCP) was used to measure developmental job experience. DCP was used because has high reliability and its validity had been tested and proven in several work environments. Responses from participants were taken. Responses were analyzed on a scale of 1 to 5 and then various statistical method used to test the fitness of the outcomes. A further examination was done to ensure that their measurements of effective states were empirically different from individual’s specific affective traits and measurement was only to include employees work related effective states. They used twelve adjectives to describe affective experiences, dependent variables. The effective experiences were measured on a scale of 1 to 4. After several statistical methods were used, the measurement was analyzed and averaged to create dimension scores and indicators which generated pleasant and unpleasant feelings. They verified their measurements and examined the measurement findings to have a well-established relationship between DJE and effective experiences.

In the analysis of the emotional intelligence they used MSCEIT version 2, a computer aided test to evaluate the participants Emotional intelligence .MSCEIT version 2 was used because had proved reasonable reliability and had ability to measure general mental ability. In the examination for advancement potential and turnover intentions among the participants three item scale was used. The researchers used tested and proven methods to measure control variable in their study. Respondents’ age, gender and organizational tenure wasincluded as control variables in their study. “Demographic variables have impacts on employees’ advancement potential and turnover intentions”,(Spector, P. E, & Brannick, M. T, 2010).

Reliability and validity

Reliability is the ability of the significant results to produce more than one off finding and inherently repeatable. The authors used Cronbach’s alpha to determine reliability of the study. If results produce a Cronbach’s alpha > 0.7 showed the results were reliable. In their study Cronbach’s alpha value was0.91 based on DJE scale. The measurement produced Cronbach’s value of 0.84 and 0.75for affective experiences, pleasant and unpleasant feelings respectively. Cronbach’s values of 0.88, 0.76 and 0.84 were obtained for emotional intelligence, advancement potential turnover intention respectively. Since the Cronbach’s alpha for all the variables was > 0.7, all tests were considered reliable.

Statistical Techniques Used to Test the Hypotheses

In their researcher works the authors employed two step structural equation modeling (SEM) to test theoretical model using MPLUS 6.11.The two step model was chosen since it permitted simultaneous analysis in a multiple association. They tested the observed data and then compared nested structural models to obtain proper information concerning the model. They computed mean and variance to establish variability. Their computational analysis produced a p-value p>0.05, indicating the measurement model had an excellent good fit and further examination was necessary. The authors carried another study, structural model analysis to compare the results, their hypothesized model produced p<0.001. When they compared the model result and alternative model found the alternative model was not a significant improvement over the hypothesized .from the measured and analyzed means first five hypothesis were held valid, while hypothesis 6a, 7, and 8 which produce p > 0.05 were announced null hypotheses and rejected. 9th hypothesis produced significant pvalue and was considered valid.

Statistical Analysis and Findings

From the research, the authors were able to establish emotional intelligence could not moderate both the relationship between DJE and unpleasant feelings and relationship between unpleasant feelings and advancement potential. They established that both high and low advancement potential is indirectly affected by DJE via pleasant and unpleasant feelings. They found that DJE can result to both pleasant and unpleasant feelings among employees .it was established DJE affect both pleasant and unpleasant feelings, unpleasant feelings affect low turnover intention while pleasant feelings affects both advancement potential and turnover intention. The illustrations are below.

Figure 1: Interaction of Unpleasant Feelings and Emotional Intelligence on Turnover Intention

Figure 2: Interaction of Unpleasant Feelings and Emotional Intelligence on Turnover Intention

 

Contributions

From the research, the authors were able to establish emotional intelligence could not moderate both the relationship between DJE and unpleasant feelings and relationship between unpleasant feelings and advancement potential. They established that both high and low advancement potential is indirectly affected by DJE via pleasant and unpleasant feelings. They found that DJE can result to both pleasant and unpleasant feelings among employees .it was established DJE affect both pleasant and unpleasant feelings, unpleasant feelings affect low turnover intention while pleasant feelings affects both advancement potential and turnover intention

Conclusions

Theoretical contributions    

Their study made theoretical contributions to the existing literatures on workplace affect and stress. They added knowledge of affect in organizations by identifying DJE as an important predictor of feeling states at work. Their research also added to the existing the stress literature by pointing out the potentially critical role of EI in coping with stressors in the workplace. As such, anyone needing to get an insight to the workplace stress can gain some understanding of the topic by referring to this research study by Dong, Seo and Bartol.

Practical Contributions and Implications for Managers

In today’s competitive business world every organization seeks to the optimal productivity that its employees can offer at any one given time. Having an environment that addresses stress and how it can be minimized if not done away with for employees is one of the most practical ways of maximizing employee productivity. It in this line that this work of research by Dong, Seo and Bartol becomes very relevant and practical for managers, who may need to effectively know to handle stress at the workplace (Hardin, 2013).  As has been outlined earlier, the study touched on several issues that concern work stress and how it can be dealt with.

Limitations

This study had two major limitations. First, the sample used was limited to just one industry. This is a limitation because there many industries in the business world. The experiences from each of these may significantly differ; essentially with regard to how stressing the workers find the environment. Secondly, the use of young managers in this presented another limitation concerning the scope of the study. This is so because different industries are managed by different managers, and some require very experienced managers in order to operate well (Kobrin et al, 2011).

Points for Improvement in the Study

In the study the scope can be extended by targeting a diverse population, such as mixing the responded managers from entry level managers, middle level manager and top level managers. This would give a more practical result concerning the topic of stress in management. Secondly, taking samples from different industries would be another way to expand the validity and make the findings of the study more reliable.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Dong,seo & Bartol. (2014). No pain, No gain: An effect based model of developmental job experience and the buffering effects of emotional intelligence. Academy of Management Journal, 57 No. 4, pp 1056-1077.

Folkman, S. and Lazarus, R. S. (1985). `If it changes it must be a process: study of emotion and coping during three stages of a college examination’,. Journal of Personality and Social Psychology,, 48, 150-170.

Hardin, J. M. & Nick T. G. (2013) Regression modeling strategies: an illustrative case study from medical rehabilitation outcomes research. Retrieved November 13th, 2014, from PubMed: http://www.ncbi.nlm.nih.gov/pubmed/10500854

Kobrin, J. L., Sandip, S., Shelby, J. H. & Chajewski, M. (2011). An Investigation of the Fit of Linear Regression Models to Data from an SAT Validity Study. Retrieved November 13th, 2014, from ETS: http://www.ets.org/research/policy_research_reports/publications/report/2011/issd

Lazarus, R. S. (1991c). Psychological stress in the workplace. Journal of Social Behavior and Personality, 6, 6-13.

Selye.H. (1983). The stress concept: Past, present, and future. New york: John Wiley.

Smith, C. and Lazarus, R. S. (1990). Emotion and adaptation. Handbook of Personality: Theory and Research, 609-637.

Spector, P. E, & Brannick, M. T. (2010). Methodological urban legends:The misuse of statistical control variables. organisational research methods, 14, 287-395.

 

Preparation of Alcohols: Reduction of Fluorenone and Lucas Test for Alcohols

 

Background& Methods

By the end of this this experiment our goal was to prepare 9-fluorenol by reducing 9-fluorenone using sodium borohydride. For this carbon-oxygen double bond specific reaction, we were assigned 1.20 grams of 9-fluorenone from our T.A. Using this value the amount of reagents used in the experiment were calculated. The reagents included were sodium borohydride, methanol, and sulfuric acid. After the reaction was complete, the final product we purified through recrystallization. To characterize the product most accurately melting point analysis and IR spectroscopy are used. Then, through the Lucas test alcohol formation was verified. The secondary product, 9-fluorenol, is compared to the primary and tertiary alcohol. After obtaining the final product IR, Lucas test, and melting point were taken to characterize it. Once completed the percent yield was calculated.

 

Within this experiment reduction, oxidation and oxidation state of carbon was used heavily. These reactions can be either organic or inorganic. In simple terms, reduction is the gain of electrons while oxidation is the loss of. This becomes a lot more complicated during the organic redox reactions. In actuality, the carbon that makes a covalent bond doesn’t gain or lose anything though the carbon atom faces a change in the electron density. Typically, the most electronegative atoms are nitrogen oxygen or halogens like Hydrogen. Once the oxidation number of the carbon atom is calculated it can be classified as either an oxidation or reduction reaction. In order to count electrons we use the oxidation station. It states the charge on the atom would be if all of the bonds were ionic. An increase in this number will result in oxidation, and a decrease in reduction. It takes a total of three steps to determine such:

  1. For every atom bound to carbon that is more electronegative than carbon add 1
  2. For every atom bound to carbon that is less electronegative than carbon subtract 1
  3. Every time carbon is bound to another carbon add 0.

The total sum results in the oxidation state of the carbon. In the reduction of 9-fluoreone to 9-fluorenol there is a change from +2 to 0 in carbon’s state.

 

{insert calculation}

 

In the reduction of 9-fluoreone to 9-fluorenol a total of three reagents are used. The following are considered reducing agents: molecular hydrogen (H2), sodium borohydride (NaBH4), and lithium aluminum hydride (LiAlH4 or LAH). Though in this lab sodium borohydride is used and becomes oxidized over the course of the reaction. In order for a reducing agent to do its job it must react which causes another molecule to be reduced.

Catalytic Hydrogenations can be utilized in the in the reduction of other pi bonds like Ketones to alkanols, amines from imines, or nitro groups to amines. Sodium borohydride and lithium aluminium hydride are called metal hydrides. Sodium borohydride and lithium alumunium hydride operate in alternative mechanism to catalytic hydrogenation. The two i.e. sodium borohydride and lithium aluminium hydride assist in the reduction by simply acting the delivery agents of hydride to to electrophilic sites. Lithium aliminium hydride is more strong than sodium borohydride and can reduce functional groups like imines, aldehydes, ketones, carboxylic acids, esters amd amides. The less strong Sodium borohydride is common for reduction of imines, aldehydes, and ketones.

A crucial aspect of the metal hydrides chemistry lies in the selectivity acquired while utilizing these reagents rather than the catalytic hydrogenation. Of all the reactions, many of the reductions done using metal hydrides can also be effected by using H2 with a metal catalyst. Metal hydrides reduce pi bonds that are polar. Due to this fact they cannot be able to reduce carbon to carbon multiple bonds. However they may be a preferable alternative to reduce a C=O or C=N bond with the presence of an alkene or alkyne. Many forms of LAH and NaBH4 are found when 3 of the 4 hydrogen attached to the central B/Li are replaced by an alkyl. Cyano or alkoxy groups. Readjustments of these groups allows the reaction rate of LAH and NaBH4 to be increased or weakened in modification of the use and selectivity of the reagents.

Having completed the TLC and the IR spectroscopy we did the Lucas classification of test for alkanols. The test differentiates between the primary, secondary and tertiary alkanols. It is analogous to the silver nitrate test utilized in Lab 7 to differentiate between primary, secondary and tertiary alkyl halides. The analogy lies in the operation of SN1 necuophilic substitution mechanism. In the test there is a mixture of ZNCl2 and HCl which increase the reactivity of alcohols towards the acids. This is due to the strength of ZNCl2 as a Lewis acid and reacts with the lone pairs of electrons of the oxygen in alcohol. The ZNCl-OH then breaks down to give carbonication , which also reacts with chloride ion forming an alkyl chloride. What determines the rate is carbonation. This implies that the rate increase with increase carbocation stability. This shows that tertiary alkanols will have a higher rate of reaction and secondary and primary alcohols them being unreactive with the Lucas test. A positive test is shown by change of the solution from being clear to cloudy when alcohol is added. This is based on the fact that alkyl chloride is not soluble in the aqueous solution whereas the alcohol we started with was. We establish whether it is a secondary or a tertiary by just noting the rate at which it reacts. Tertiary alcohols react immediately whereas secondary alkanols may take 5-20 minutes to react. The Lucas test is ideal for the alkanols with six or fewer carbons. The alkanol we start with must be soluble in the Lucas reagent.

 

Methodology

Part 1: Synthesis of 9-fluorenol

We had been assigned 1.2 g of 9-fluorenone and then calculated the amount of the other reagents used in the lab today. After the calculation we poured 9-fluoronone into a 50 ml flask and calculated the value of methanol. We then dissolved the 9-fluorone by swirling and heating. The solution was put to cool down to the room temperature. Sodium borohydride was then added to the reaction flask. The flask was swirled vigorously to dissolve the reagent. The reaction flask was not closed. This is because it can be explosive incase hydrogen gas builds up in the bottle. The combination of occasional swirling and cooling was done for about 20 minutes within which the solution had cooled down to room temperature. However after the first about 10 minutes the solution was not yet colorless so we added 6 g of sodium borohydride and continued with the process. Before working up the solution we took a TLC. The ratio of 1 to 9 Ethyl acetate to hexanes was placed in the beaker. We drew a line on the TLC silica plate and three dots were placed on the plate. The three dots included the first which was pure 9-fluoronone , followed by the second which was 9- fluoronone and the mixture , finally the last was the mixture. The plate was then observed under UV light. We calculated the values of RF. When the TLC was finished, we worked up the reaction by adding up 3M of Sulphuric acid to the reaction mixture. The solid that was formed when we added the acid was reduced by heating and swirling the solution for about 5 to 7 minutes. A watch glass was also used to minimize solvent loss. The flask was then allowed to calmly cool at room temperature before transferring it to an ice water bath until it precipitated. The precipitate in solid form was then taken out and washed till it was neutral. A pH paper was used to confirm whether the pH was neutral. The solid was then let to dry. The solution started to re crystallize; the minimum amount of hot methanol was added until it dissolved. When the 9-fluoronone was dissolved the solution was taken out of heat and the solution let to cool. When I cooled to room temperature the contents were transferred to an ice bath. The final product was filtered, dried, weighed and the percentage yield calculated. Melting point and IR were then taken out. The product obtained was put in the capillaries; they were then dropped down to ensure the product was well packed. It was then transferred to the melting point apparatus. The IR machine was cleaned the sample placed on it for analysis.

 

Part II: Confirmation of alcohol formation by Lucas classification test.

Preparation of three test tubes was done by adding 1 ml of Lucas reagent to each tube. We added 3 ml of tertiary alcohol to one test tube. That test-tube was then shaken. The procedure was repeated for the other two secondary and primary alcohols. Our products were solid so we first needed to prepare a solution of 9-fluorenol in 3ml of ethanol before performing the test.

 

 

 

 

 

 

DATA ACQUISITION

 

Compound Molecular Weight (g/mol) d(g/mL) or M(mmol/mL) Rxn Weight or Volume (g or mL) mmol Equivalents
9-Fluorenone 180.10 n/a 1.5g 6.66 1.0
Sodium Borohydride 37.83 n/a 0.126g 3.33 0.5
Methanol 32.04 0.792 g/mL 12.12mL 299.7 45
Sulfuric Acid 98.08 1.00 g/mL

3.00 mol/L

4.4mL 13.32 2.0

 

Percent Yield

States the correct amount of the product that was made

Percent Yield = (Actual Yield/ Theoretical Yield) * 100

 

Percent Yield= (1.25g/1.20g) * 100= 104.2% of 9-Fluorenol

 

Discussion of Collected Data

The biggest problem with our collected data is that our percent yield is above 100 percent. Typically this is unlikely if the starting measured amount is less but may have occurred if the final product hadn’t dried enough or the initial measurement of 9-Fluorenone was greater than the 1.2 grams assigned by our T.A.

IR SPECTROSCOPY

Molecular Motion Theoretical Wavenumber (cm-1) Actual Wavenumber (cm-1)
O-H Stretch (Alcohol) 3400-3300 3306.53
Unsaturated C-H Stretch ~3020 3037.30
Aromatic Ring ~1450 1449.50

 

TLC

The reaction is complete when there is no more 9-Fluorenone in the reaction mixture.

 

LANE SOLVENT SOLUTE
1 2.7 mL 2.3 mL
2  
3 0.0 mL

 

Rf=distance spot moved/distance solvent moved

Rf=2.3/2.7= 0.852

Rf=0.0/2.7=0

ANALYSIS AND CLASSIFICATION TESTS

TESTS

   
Melting Point Analysis Ideal: 152-158°C

Actual: 152 °C

 
Lucas Test    
3° Alcohol Cloudy POSITIVE. The solution became cloudy rather quickly.
2° Alcohol Cloudy POSITIVE.  The solution became cloudy within a couple of minutes
1°Alcohol Clear NEGATIVE. The solution had no reaction therefore remained clear. No visible reaction.

 

 

CONCLUSION

By the end of this experiment we were able to conduct a complete reduction reaction of 9-Fluorenone to 9-Flurenol with the use of sodium borohydride. In the end we were able to produce 1.25 grams of 9-Fluorenol giving us a percent yield of 104.2% proving that our goal was achieved.  It is likely this value is high due to the fact that our product was not completely dry. Other possibilities for error may be directed to incorrect measurement of the original amount of 9-Fluorenone, 1.2 grams. Our melting point for the product was 152 °C, which is within the ideal range of 152-158°C.

 

Multiple tests were conducted post reaction completion such as the TLC test. In this experiment, the TLC test differentiates from other labs since it monitors the progress of the reaction. When there isn’t any 9-Fluorenone in the reaction mixture then the reaction is complete, or disappearance of the starting material. The Rf values of two spots on a TLC plate provided evidence of the identity of our compound, and the success of our fluorine reduction reaction. The more polar compound has a lower Rf value, and vice versa. Our TLC had a retention factor of 0.852 and 0.00. In short, this means that our reaction was complete since there is no more 9-Fluorenone in the reaction mixture.

 

The other test that was conducted was the Lucas classification test. In this test all 3 types of alcohols undergo 3 different reaction rates. It starts with tertiary then secondary, and finally primary alcohol reactions. Typically, primary alcohols don’t react with Lucas reagent at room temperature since it requires a very high temperature. During the SN1 mechanism the RDS is carbocation formation. In order for the test to be positive the solution will become cloudy when the solutions are added. If the solution remains clear in the time allotted then it results in a negative test, no reaction occurred.IR Spectroscopy confirmed that the experiment was conducted correctly by showing that 9-Flurenol was formed. An O-H stretch, alcohol, was seen at 3306.53 cm-1. An unsaturated C-H stretch was seen at 3037.30 cm-1 and an aromatic ring at 1449.50 cm-1.

 

Possible errors may have been made during the experimentation process. Again, our mass of 9-Flurenol was greater than the 1.20 grams of 9-Fluorenone that was used in the experiment. This was due to the excess amount of water that was retained by the product, 9-Flurenol. Other possible errors that may have occurred when our product was stuck on the vacuum. If our product had been thoroughly dried then a significant difference may have been seen in a loss of 9-Flurenol in our final weighing.

 Chemistry department

 

 

 

 

 

 

Amplification vs. Dilution

 

Dilution refers to the phenomenon whereby an introduction of a host in the system causes a reduction of the pathogen population in that system.  On the other hand, amplification refers to the phenomenon whereby the addition of a host to the system causes an increase in the pathogen population in that system. In other words, the dilution effect occurs when biodiversity and the risk of disease are inversely proportional while amplification is borne of a positive interaction between biodiversity and disease risk. Dilution and amplification scenarios are abundant in the human environment depending on the nature of the host-pathogen competition in a particular ecosystem.

In the dilution effect, once a host organism is introduced into a population of pathogens, it creates a diversity of species in the setting and causes competition between the diverse species. This competition, in turn, causes a reduction in the pathogenic efficiency of the more dominant of the two species.  Hence, this effect resulted in a decreased abundance of pathogens, a decreased disease risk and decreased the intraspecific transmission. In the amplification effect, the introduction of a host into an ecological setting enhances pathogenicity hence causes an increase in pathogen abundance, an increased disease risk, and interspecific transmission.

Of late, there has been a heated discussion as to whether the postulate that biodiversity dilutes disease holds ground. In some way, amplification and dilution mechanism have illustrated that there is a relationship between biodiversity and the outcome of the disease. Many believe that changes in biodiversity can cause different outcomes on the risk of diseases, such as amplification and dilution, and which can influence the disease effect in the community. Amplification effect is caused when there is a positive relationship between disease risk and biodiversity, whereas the dilution effect takes place when disease risk and biodiversity are inversely related (Ostfeld, Keesing & Eviner, 2008). When a variety of species are infected by the same pathogen, the target host species have different abilities in fighting against the pathogen, acquiring the pathogen, and in transmitting the pathogen to others. Therefore, alterations in biodiversity affect the composition of the host species resulting in a change in the community.

Amplification occurs in a scenario where adding species in a community that has lower diversity and contain unfavorable hosts increases the number of hosts that are highly competent. For instance, when intraspecific transmissions of the pathogen seem to drive the disease, the amplification will occur. In this case, the diversity of the species resulted in an increase in the disease.

Some disputants of the debate argue that dilution effects are more likely going to occur in the pathogens with frequency-dependent transmission, whereas amplification is common in pathogens with density–dependent transmission (Holt et al., 2003). In density-dependent transmission, the infection transferred from infected to uninfected depends on the total number of infecting organisms (population density). Therefore, the rate of disease transmission increases with the increase in population density. On the other hand, population density does not affect frequency-dependent transmissions; what matters in this case is the frequency of contact with the infected organism.

The Lyme disease system is a good instance of the dilution effect, and it is caused by bacteria that are factored by ticks. When larval ticks are born, they are uninfected, but become infected after consuming a blood meal from a host that is infected by the pathogen. Mice are, usually, highly competent hosts that transmit the bacteria to the ticks. After feeding on the blood, the nymph molts into a nymph that also has to take a blood meal to transform into an adult tick. The infected nymphs transmit the pathogen to the hosts as they take a blood meal. These nymphs feed on human beings and other mammalian hosts. In this disease, the pathogen infection is high when there is a large population of ticks that are infected, in an area.  The number of ticks that are infected can increase with high prevalence or high total densities of infected ticks. However, in Lyme disease, the vectors become infected after they bite the infected hosts; the pathogen is not transmitted from parent to offspring (Wood & Lafferty, 2013).  In other words, all hatched larval ticks are uninfected and become infected only after consuming a blood meal from a host that is infected.

I think that since that since the status quo is that the dilution effect has not been significantly implicated in disease reduction, more research is required to clarify this issue. However, I feel that the dilution effects hold great promise for disease management. According to the case study above, the population can be protected against diseases by altering the biodiversity to cause a dilution effect. Researchers and pathologists should work together towards the goal of preserving biodiversity while they reduce the risk of harmful and infectious disease. These experiments show that studying the community structure and biodiversity in relation to species variation, genetic variation and ecosystem variation may contribute to the study of disease dynamics. Understanding the variation in a particular community may enable researchers to control the effect of the disease to the population.

Columbia University

 

 

 

Annotated bibliography

 

 

‘Women in World War II’ was authored by Dr. Kristine M. McCusker. The paper discusses the role of women during World War II. It demonstrates how women were targeted by the United States government during the war. The paper further explores how such circumstances were fundamental in shaping the lives of women after the war. The resultant effects were both positive and negative. The roles and responsibilities of women changed during the World War II. Women took part in initiatives to aid the United States government end the war. After the war ended, the government and media recognized the new roles of women. This paper will be helpful in linking their roles in the war and the effects on them.

 

Lockhart and Jenna in “Women Who Answered the Call: World War II; A Turning Point for Women in the Workforce “state that that the World War II was a turning point for women in the workforce. During the 1940’s married women overwhelmingly began to participate in the labour force. The authors admit that the World War II imparted economic and social changes among the women. Some of the changes however were negative. The article is, therefore resource as uncovers the effects of World War II on women. The substantial increase in the number of employed women during the World War II greatly influenced women in employment after the post-war period.

 

Authored by Cynthia Cupit and Avigdor Klingman, “Children and war” explores the effects of war on children.  The paper examines both the direct and indirect effects. It is relevant for this research paper as it draws much from the post-war surveys on children conducted after the aftermath of World War II. Among the effects discussed in this paper include post-traumatic stress, many children becoming orphans. Some children had to evacuate their homes and live with strangers. The traumatic events of the war had long-lasting effects on the children.

 

As Akbulut-Yuksel documents in the article ‘Children of war’, war have detrimental effects on the society including on children. Such effects may become long-lasting and continuous impacts on children. As the author suggests, children and their mothers undergo very many challenges during warfare. The experiences in most cases are undesirable to cope up with. Through the use of a case study on German children, the article is relevant to this research as it paper explores the causal relationship of long-term effects of large-scale physical destruction that occur during war. It further discusses the specific impacts on children’s educational attainment and other social aspects as health.

Zeiler and Daniel in the book A Companion to World War II, discusses a range of issues that related to World War II. As the author admits, it is a time on the world history that represented a time of industrial revolution, modernism and societal shifts.  This book provides detailed topics that provide links between the happenings of the World War II that had dire effects on women and children, the author notes that generations that came after war, were most affected. The book uncovers the human experiences during the time and explores the conflicts that surrounded the war. Emphasis was also done on the horrific and suffering and ultimate consequences caused by