Using Independent Bernoulli Random Variables to Model Gender Hiring Practices

Gender bias is a problem in the workforce at large. In order for society to progress it is important that hiring practices do not use gender as a competitive factor. Hiring practices based on gender can be represented statistically using Bernoulli Random Variables and the Beta and Binomial distributions.Using the moment generating function (MGF) of the Bernoulli and Binomial Distributions, it is possible to calculate the expected value (mean) and variance for the number of women hires for n positions. The probability generating function (PGF) of a sample size n can be used to find the probability of hiring a specific number of women (X). The PGF when solved for P(X = 0) reveals the probability of no women hired for n positions, while P(X less than or equal to 1) gives the probability that one or no women were hired. A computer program was used to run trials to simulate different male/female distributions using recent data on the proportion of women earning a PhD in a variety of disciplines. The simulations were used to represent hiring results for seven faculty positions. Situations where the female proportion is centered at 0.3, 0.5, and 0.7 were studied to account for a range of situations explained by the data researched. Trials that included random proportions of women for each position were run as well. The Chi-Squared Goodness-of-Fit Test will compare the Binomial cumulative distribution function to the sum of Bernoulli cumulative distribution function in order to find a critical value at which it is acceptable to approximate the Bernoulli distribution with a Binomial distribution for various simulations. Simulations will be run to find the average difference between the probabilities that one or more women are hired. Results reveal that it is actually unusual for employers to hire one or no women for seven positions, which could provide evidence of gender bias and that the Binomial distribution approximates each situation fairly well for varying measures of central tendency

Acoustic Emission Linear Pulse Holography

This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of the received signals is measured at successive points on the scan. The innovation proposed in this paper is the utilization of the crack generated acoustic emission as the acoustic source and generation of a line image of the crack as it grows. A thirty-two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The phases are calculated using the pulse time-of-flight (TOF) times from the reference transducer to the array of receivers. Computer reconstruction of the image is accomplished using a one-dimensional FFT algorithm (i.e., backward wave). Experimental results are shown which graphically illustrate the unique acoustic emission images of a single point and a linear crack in a 100 mm × 1220 mm × 1220 mm aluminum plate

Promoting adherence to antiretroviral therapy: the experience from a primary care setting in Khayelitsha, South Africa.

OBJECTIVE: To describe the approach used to promote adherence to antiretroviral therapy (ART) and to present the outcomes in the first primary care public sector ART project in South Africa. DESIGN: The study is a prospective open cohort, including all adult patients naive to previous ART who received antiretroviral treatment in Khayelitsha, from May 2001 to the end of 2002. Patients were followed until their most recent visit before 31 July 2003. METHODS: Plasma viral load was determined at 3, 6, 12, 18 and 24 months after ART was initiated, and CD4 cell counts 6-monthly. Kaplan-Meier estimates were determined for the cumulative proportions of patients surviving, and patients with viral load suppression and viral rebound. RESULTS: A total of 287 patients were initiated on triple therapy. The probability of survival was 86.3% at 24 months. The median CD4 cell count gain was 288 cells/microliters at 24 months. Viral load was less than 400 copies/ml in 89.2, 84.2 and 69.7% of patients at 6, 12 and 24 months, respectively. The cumulative probability of viral rebound (two consecutive HIV-RNA measurements above 400 copies/ml) after achieving an HIV-RNA measurement below 400 copies/ml was 13.2% at 18 months. CONCLUSION: The study shows that, with a standard approach to patient preparation and strategies to enhance adherence, a cohort of patients on ART can be retained in a resource-limited setting in a developing country. A high proportion of patients achieved suppression of viral replication. The subsequent probability of viral rebound was low

Research Notes: Soybean seed β-amylase variants

Hildebrand and Hymowitz (1980a) reported that two soybean genotypes were found that lack detectable seed a- amylase activity . The cultivar \u27Chestnut\u27 produces an inactive a- amylase protein, Span (Hildebrand and Hymowitz , 1980b) ; \u27Altona\u27 is a mixture of genotypes that have a a-amylase protein of normal activity (sp1b) or lack it entirely (sp1) (Hildebrand and Hymowitz , 1980b) . Chestnut was selected from \u27Habaro\u27 and introduced into the U.S. as PI 20,405 in 1906 from Kharbarovsk, USSR (Hymowitz et al ., 1977)

Resolving velocity space dynamics in continuum gyrokinetics

Many plasmas of interest to the astrophysical and fusion communities are weakly collisional. In such plasmas, small scales can develop in the distribution of particle velocities, potentially affecting observable quantities such as turbulent fluxes. Consequently, it is necessary to monitor velocity space resolution in gyrokinetic simulations. In this paper, we present a set of computationally efficient diagnostics for measuring velocity space resolution in gyrokinetic simulations and apply them to a range of plasma physics phenomena using the continuum gyrokinetic code GS2. For the cases considered here, it is found that the use of a collisionality at or below experimental values allows for the resolution of plasma dynamics with relatively few velocity space grid points. Additionally, we describe implementation of an adaptive collision frequency which can be used to improve velocity space resolution in the collisionless regime, where results are expected to be independent of collision frequency.Comment: 20 pages, 11 figures, submitted to Phys. Plasma

Research Notes : Seed acid phosphatase genotypes of cultivars in the USDA soybean collection

Soybeans have three cultivar-specific electrophoretic fonns of a seed acid phosphatase (Gorman and Kiang, 1977). Hildebrand et al. (1980) reported that the three acid phosphata se fonns are inherited as codominant alleles at a single locus. The symbol Ap^a was assigned to the slow form, Ap^b to the intermediate and Ap^c to the fast form

Mapping Residual Stress Fields by Ultrasonic Tomography

It is well known that the velocity of sound in a solid is affected by stress. This phenomenon is a third order effect, and has been used primarily as a research tool to determine the Lame and Murnaghan elastic constants for various materials. A few preliminary attempts to use it for stress analysis have also been made. In this paper we describe the first attempt to combine this effect with the newly revived mathematical technique known as Computerized Axial Tomography (CAT) to provide quantitative maps of velocity within thick metal sections. From these maps , it is possible to infer the state of residual stress within the material. The technique requires that time-of-flight profiles through a section of the solid be made in a number of angular directions. This is equivalent to measuring the velocity through the solid from many different directions in a single plane. The computer takes the set of data so gathered and inverts it to produce a cross-sectional plot of velocity versus position. We have succeeded in mapping velocity anomalies as low as 0.21% and estimate that 0.5% is technically feasible. This kind of sensitivity should allow us to map stress anomalies as low as 1000 psi/inch in steel. We will also describe an experiment with a mild steel section in which we inserted an oversized pin by shrink fitting. The reconstruction clearly shows the high compressive stress within the pin, and the tensile .stress in the metal surrounding the pin

Far infrared maps of the ridge between OMC-1 and OMC-2

Dust continuum emission from a 6 ft x 20 ft region surrounding OMC-1 and OMC-2 were mapped at 55 and 125 microns with 4 ft resolution. The dominant features of the maps are a strong peak at OMC-1 and a ridge of lower surface brightness between OMC-1 and OMC-2. Along the ridge the infrared flux densities and the color temperature decreases smoothly from OMC-1 to OMC-2. OMC-1 is heated primarily by several optical and infrared stars situated within or just at the boundary of the cloud. At the region of minimum column density between OMC-1 and OMC-2 the nearby B0.5 V star NU Ori may contribute significantly to the dust heating. Near OMC-2 dust column densities are large enough so that, in addition to the OMC-2 infrared cluster, the nonlocal infrared sources associated with OMC-1 and NU Ori can contribute to the heating