Concisely, describe the particular features of Creighton’s and McClintock’s experiment that allowed them to prove Morgan’s hypothesis that coupling and repulsion results from the physical exchange of DNA between homologous chromosomes?

Below you will find part of a job description for a part-time position in a campus bookstore. Read each task in the job description and identify those tasks for which training (rather than employee selection techniques) would be appropriate. In the next exercise, you will be asked to determine how to train the employees for each of the tasks you identify.

Textbook Clerk

Job Summary

The Textbook Clerk is a university work-study position. The student hired for this job is responsible for assisting the Textbook Supervisor with book inventories, shelving duties, and customer requests. Additionally, the Textbook Clerk performs general clerical and messenger duties and operates the cash register when additional assistance is needed. Work Activities

Inventory Duties - Inventories books by section and course number - Informs supervisor of number of books to be returned - Writes ISBN-13 on inventory sheet - Verifies all information as typed on each textbook requisition - Records price information

Shelving Duties - Shelves returned books - Straightens shelves - Removes previous semester's textbooks from store shelves at the end of each semester - Shelves used books in the stockroom by title - Shelves new books in the stockroom by publisher - Places shelf cards on appropriate shelf - Dusts shelves - Dusts books

Customer Relations Duties - Phones professors regarding new textbook editions - Mails book arrival notices to professors

Clerical Duties - Creates and prints shelf cards - Creates and prints book arrival notices - Types PU-6 Forms - Photocopies book orders and notices about book arrivals

Messenger Duties - Delivers materials or messages to other employees - Delivers materials to university departments 100

Cash Register Duties

- Writes name on register tab at beginning and end of shift - Watches customers entering store to make sure they do not take books and backpacks into store - Tabulates price of purchases using cash register - Counts appropriate change and gives it to customers - Pages employee on register list to assist with checkout when lines are long - Approves student's’ checks by validating university ID or by certifying driver's license - Approves out-of-town checks by verifying name, address, and phone number with driver's license - Pages supervisor to fill out void slips - Completes in-slip forms for returns - Sells laundry tickets, computer disks, and dissection coupons to students - Verifies textbook tags for price and author codes to ensure that the correct tag is still on the textbook - Pages supervisor if tag and code are incorrect

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Your company offers a denied-benefit pension plan to each of its employees. The plan will make a monthly payment to each retiree of $4 thousand, next month. In each subsequent month, the payment will grow by an annualized rate of 2% to adjust for inflation. There are currently 100 retirees, and you estimate that this number will remain the same, indefinitely. The government mandates that (i) pension liabilities must be discounted at an annualized rate of 4%, and (ii) pension liabilities must be 75% funded (that is, the pension fund must be funded at 75% of the present value of the liabilities). (a) How much money must your rm contribute to its pension fund. (b) Consider the following variation on (a). Yours is a young company { a sexy startup. You don't have any retirees right now, but you do make pension promises to your young workers. You estimate that 20 years from now the first cohort of 50 workers will retire, receiving their first monthly payment one month after retiring (received in 241 months). Going forward, you expect the pool of retirees to remain stable, at 50. How much money must your firm contribute now in order to fulfil the government mandate?

Read the following text and apply at least 3 guidelines for judging whether the observed association is causal to answer question.

Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder and is associated with significant burden. More than half of children with ADHD continue to have this disorder in adulthood and live with many long-term adverse health and social conditions. The worldwide ADHD prevalence in children has been estimated at 7.2%. Genetic factors have been demonstrated to play a role in ADHD etiology with a heritability of 70%-80%. Other factors that play a role include low level of paternal education, low maternal age at delivery, prenatal smoking, prenatal illicit drug use, birth complications, low birth weight, preterm delivery, neonatal jaundice, childhood asthma, maternal depression, use of prenatal antidepressants and acetaminophen exposure. It has been demonstrated that exposure to antibiotics in early life disrupts the equilibrium of gut microbiota and could potentially contribute to the development of ADHD. In a population-based cohort study, researchers found that early antibiotic exposure was associated with the development of ADHD (RR=1.10, 95% Confidence interval 1.01, 1.65).

Is the association between early antibiotic exposure and ADHD causal?

Background: Despite their antimicrobial potential, vaginal lactobacilli often fail to retain dominance, resulting in overgrowth of the vgna by other bacteria, as observed with bacterial vaginosis. It remains elusive however to what extent interindividual differences in vaginal Lactobacillus community composition determine the stability of this microflora. In a prospective cohort of pregnant women we studied the stability of the normal vaginal microflora (VMF) (assessed on Gram stain) as a function of the presence of the vaginal Lactobacillus index species (determined through culture and molecular analysis with tRFLP).

Results: From 100 consecutive Caucasian women vaginal swabs were obtained at mean gestational ages of 8.6 (SD 1.4), 21.2 (SD 1.3), and 32.4 (SD 1.7) weeks, respectively. Based on Gram stain, 77 women had normal or Lactobacillus-dominated vaginal microflora (VMF) during the first trimester of which 56 remained normail in the third trimester. Th3 remaining 23 women tested abnormal in the first trimester and 13 of them converted in the second or third trimester.

Test the null hypothesis that having an abnormal result in the first trimester is related to having an abnormal result in the third trimester (Hint: What type of chi-square test is this?). (5 pts).