A microbiological method for the determination of choline by use of a mutant of Neurospora

Previous communications from this laboratory have described the production of biochemical mutants in the mold Neurospora by means of ultraviolet and x-rays (1, 2). Such mutants are characterized by the inability to carry out specific chemical syntheses which normally occur in the unmutated, or wild type, strain. In each case which has been genetically analyzed the failure of the synthesis has been found to be related to the mutation of a single gene. The strain to be described, known as No. 34486, or cholineless, arose from a culture of wild type Neurospora crassa which had been irradiated with ultraviolet light. It was found to be unable to grow in a medium containing only salts, sugar, and biotin, but it grew normally on the addition of a mixture of water-soluble vitamins. When the components of the mixture were tested singly, it was found that the addition of choline alone permitted normal growth. Up to the present, no completely satisfactory method for the determination of choline in natural products and tissue extracts has been described. Chemical methods, such as precipitation of the reineckate, lack specificity, while the biological method of Fletcher, Best, and Solandt (3) is time-consuming and difficult, and “possesses many dangerous pitfalls for the chemist” (4). The whole subject has been critically reviewed by Best and Lucas (4). It was therefore of interest to determine whether the Neurospora mutant is a suitable test organism in a quantitative assay for choline. The experiments to be described show that this is the case and form the basis of a simple, sensitive, and specific method for the determination of choline in natural products. By this procedure it is possible to determine choline in a concentration of 0.02 mg. per liter; routine analyses can be run on 100 mg. samples of material

Letter to Sonora Dodd from W. N. Beadle, July 3, 1943

Letter to Sonora Dodd from W. N. Beadle, Vice President of Byron Jackson Co., Los Angeles, California.https://digitalcommons.whitworth.edu/fathers-day-correspondence/1131/thumbnail.jp

Do social networks impact perceived loneliness in caregivers to older adults with chronic conditions?

The abstract is not published at this time to protect intellectual property

Ventromedial Prefrontal Cortex Is Critical for Helping Others Who Are Suffering

Neurological patients with damage to the ventromedial prefrontal cortex (vmPFC) are reported to display reduced empathy toward others in their daily lives in clinical case studies. However, the empathic behavior of patients with damage to the vmPFC has not been measured experimentally in response to an empathy-eliciting event. This is important because characterizing the degree to which patients with damage to the vmPFC have lower empathic behavior will allow for the development of targeted interventions to improve patients’ social skills and in turn will help family members to better understand their impairments so they can provide appropriate supports. For the first time, we induced empathy using an ecologically-valid empathy induction in neurological patients with damage to the vmPFC and measured their empathic emotional responses and behavior in real time. Eight neurological patients with focal damage to the vmPFC were compared to demographically-matched brain-damaged and healthy comparison participants. Patients with damage to the vmPFC gave less money in the empathy condition to a person who was suffering (a confederate) than comparison participants. This provides the first direct experimental evidence that the vmPFC is critical for empathic behavior toward individuals who are suffering

Effects of Social Networks and Caregiver Characteristics on Loneliness in Caregivers to Older Adults with Chronic Conditions

Caregivers to older adults with chronic conditions may experience physical and mental health issues, such as depression and loneliness, due to the stressful nature of providing daily care. Loneliness levels also may be affected by caregiving characteristics (e.g., time spent on caregiving per week), as well as differing levels of social support. Yet, few studies have specifically examined the relationship between loneliness, caregiving characteristics and social support in caregivers to older adults with chronic conditions. Understanding the risk factors for loneliness among caregivers may provide insights into ways to improve caregiver well-being. This study aims to investigate differences in loneliness between caregivers and non-caregivers and associations with caregiving and social network characteristics. In this study, participants will include healthy adult caregivers and non-caregivers who will complete a series of measures assessing loneliness, social support, social networks and caregiving characteristics. This information will be used to map social networks, social interaction frequency, and examine relationships with loneliness among caregivers and non-caregivers

Managerial Work in a Practice-Embodying Institution - The role of calling, the virtue of constancy

What can be learned from a small scale study of managerial work in a highly marginal and under-researched working community? This paper uses the ‘goods-virtues-practices-institutions’ framework to examine the managerial work of owner-directors of traditional circuses. Inspired by MacIntyre’s arguments for the necessity of a narrative understanding of the virtues, interviews explored how British and Irish circus directors accounted for their working lives. A purposive sample was used to select subjects who had owned and managed traditional touring circuses for at least 15 years, a period in which the economic and reputational fortunes of traditional circuses have suffered badly. This sample enabled the research to examine the self-understanding of people who had, at least on the face of it, exhibited the virtue of constancy. The research contributes to our understanding of the role of the virtues in organizations by presenting evidence of an intimate relationship between the virtue of constancy and a ‘calling’ work orientation. This enhances our understanding of the virtues that are required if management is exercised as a domain-related practice

Time series prediction via aggregation : an oracle bound including numerical cost

We address the problem of forecasting a time series meeting the Causal Bernoulli Shift model, using a parametric set of predictors. The aggregation technique provides a predictor with well established and quite satisfying theoretical properties expressed by an oracle inequality for the prediction risk. The numerical computation of the aggregated predictor usually relies on a Markov chain Monte Carlo method whose convergence should be evaluated. In particular, it is crucial to bound the number of simulations needed to achieve a numerical precision of the same order as the prediction risk. In this direction we present a fairly general result which can be seen as an oracle inequality including the numerical cost of the predictor computation. The numerical cost appears by letting the oracle inequality depend on the number of simulations required in the Monte Carlo approximation. Some numerical experiments are then carried out to support our findings

First principle study of intrinsic defects in hexagonal tungsten carbide

The characteristics of intrinsic defects are important for the understanding of self-diffusion processes, mechanical strength, brittleness, and plasticity of tungsten carbide, which present in the divertor of fusion reactors. Here, we use first-principles calculations to investigate the stability of point defects and their complexes in WC. Our calculation results confirm that the formation energies of carbon defects are much lower than that of tungsten defects. The outward relaxations around vacancy are found. Both interstitial carbon and interstitial tungsten atom prefer to occupy the carbon basal plane projection of octahedral interstitial site. The results of isolated carbon defect diffusion show that the carbon vacancy stay for a wide range of temperature because of extremely high diffusion barriers, while carbon interstitial migration is activated at lower temperatures for its considerable lower activation energy. These results provide evidence for the presumption that the 800K stage is attributed by the annealing out of carbon vacancies by long-range migration.Comment: Submitted to Journal of Nuclear Material