950 research outputs found
Discrimination in a Rank Order Contest: Evidence from the NFL Draft
This paper examines discrimination in the NFL draft. The NFL is a favorable empirical setting to examine the role of skin
color because franchise selectors are required to make rank-order judgements of players based on noisy signals of future
productivity. Since wages are tightly related to the rank-order of the draft for the first four years of a playerâs career, even
if discrimination plays only a marginal role in selection, there could be a large discriminatory impact. We observe racial
differences in drafting. However, much of the variation is explained by Black and White players selecting into different
playing positions. Conditional upon a large set of control variables, including athletic performance at a marque selection
event (the NFL combine), we do not find robust evidence of racial discrimination in NFL drafting between 2000 and 2018.
However, we do find some evidence that Black players are disadvantaged relative to White players in later rounds of the draf
Search complexity and resource scaling for the quantum optimal control of unitary transformations
The optimal control of unitary transformations is a fundamental problem in
quantum control theory and quantum information processing. The feasibility of
performing such optimizations is determined by the computational and control
resources required, particularly for systems with large Hilbert spaces. Prior
work on unitary transformation control indicates that (i) for controllable
systems, local extrema in the search landscape for optimal control of quantum
gates have null measure, facilitating the convergence of local search
algorithms; but (ii) the required time for convergence to optimal controls can
scale exponentially with Hilbert space dimension. Depending on the control
system Hamiltonian, the landscape structure and scaling may vary. This work
introduces methods for quantifying Hamiltonian-dependent and kinematic effects
on control optimization dynamics in order to classify quantum systems according
to the search effort and control resources required to implement arbitrary
unitary transformations
Micro Electron MicroProbe and Sample Analyzer
A proposed, low-power, backpack-sized instrument, denoted the micro electron microprobe and sample analyzer (MEMSA), would serve as a means of rapidly performing high-resolution microscopy and energy-dispersive x-ray spectroscopy (EDX) of soil, dust, and rock particles in the field. The MEMSA would be similar to an environmental scanning electron microscope (ESEM) but would be much smaller and designed specifically for field use in studying effects of geological alteration at the micrometer scale. Like an ESEM, the MEMSA could be used to examine uncoated, electrically nonconductive specimens. In addition to the difference in size, other significant differences between the MEMSA and an ESEM lie in the mode of scanning and the nature of the electron source
Isotopic labeling of the heme cofactor in cytochrome p450 and other heme proteins.
A recombinant bacterial expression system that generates 13C-labeled heme or 15N-labeled heme in functional cytochrome P450 enzymes and other heme-containing systems is reported here using a mutant strain of Escherichia coli (HU227) in which the HemA gene is inactive. By synthesizing several isotopomers of aminolevulinic acid with 13C or 15N at different locations, isotopes have been incorporated with high abundance into the heme cofactor of five different cytochrome P450 isoforms, along with one peroxidase. Confirmed both 13C- and 15N-incorporation; spectral and catalytic assays show the labeled enzymes produced in this system are functional
Kepler Exoplanet Candidate Host Stars are Preferentially Metal Rich
We find that Kepler exoplanet candidate (EC) host stars are preferentially
metal-rich, including the low-mass stellar hosts of small-radius ECs. The last
observation confirms a tentative hint that there is a correlation between the
metallicity of low-mass stars and the presence of low-mass and small-radius
exoplanets. In particular, we compare the J-H--g-r color-color distribution of
Kepler EC host stars with a control sample of dwarf stars selected from the
~150,000 stars observed during Q1 and Q2 of the Kepler mission but with no
detected planets. We find that at J-H = 0.30 characteristic of solar-type
stars, the average g-r color of stars that host giant ECs is 4-sigma redder
than the average color of the stars in the control sample. At the same time,
the average g-r color of solar-type stars that host small-radius ECs is
indistinguishable from the average color of the stars in the control sample. In
addition, we find that at J-H = 0.62 indicative of late K dwarfs, the average
g-r color of stars that host small-radius ECs is 4-sigma redder than the
average color of the stars in the control sample. These offsets are unlikely to
be caused by differential reddening, age differences between the two
populations, or the presence of giant stars in the control sample. Stellar
models suggest that the first color offset is due to a 0.2 dex enhancement in
[Fe/H] of the giant EC host population at M_star = 1 M_Sun, while Sloan
photometry of M 67 and NGC 6791 suggests that the second color offset is due to
a similar [Fe/H] enhancement of the small-radius EC host population at M_star =
0.7 M_Sun. These correlations are a natural consequence of the core-accretion
model of planet formation.Comment: 15 pages, 8 figures, and 1 table in emulateapj format; accepted for
publication in Ap
Diagnostic stability in young children at risk for autism spectrum disorder:A baby siblings research consortium study
BACKGROUND: The diagnosis of autism spectrum disorder (ASD) made before age 3 has been found to be remarkably stable in clinic- and community-ascertained samples. The stability of an ASD diagnosis in prospectively ascertained samples of infants at risk for ASD due to familial factors has not yet been studied, however. The American Academy of Pediatrics recommends intensive surveillance and screening for this high-risk group, which may afford earlier identification. Therefore, it is critical to understand the stability of an ASD diagnosis made before age 3 in young children at familial risk. METHODS: Data were pooled across 7 sites of the Baby Siblings Research Consortium. Evaluations of 418 later-born siblings of children with ASD were conducted at 18, 24, and 36 months of age and a clinical diagnosis of ASD or Not ASD was made at each age. RESULTS: The stability of an ASD diagnosis at 18 months was 93% and at 24 months was 82%. There were relatively few children diagnosed with ASD at 18 or 24 months whose diagnosis was not confirmed at 36 months. There were, however, many children with ASD outcomes at 36 months who had not yet been diagnosed at 18 months (63%) or 24 months (41%). CONCLUSIONS: The stability of an ASD diagnosis in this familial-risk sample was high at both 18 and 24 months of age and comparable with previous data from clinic- and community-ascertained samples. However, almost half of children with ASD outcomes were not identified as being on the spectrum at 24 months and did not receive an ASD diagnosis until 36 months. Thus, longitudinal follow-up is critical for children with early signs of social-communication difficulties, even if they do not meet diagnostic criteria at initial assessment. A public health implication of these data is that screening for ASD may need to be repeated multiple times in the first years of life. These data also suggest that there is a period of early development in which ASD features unfold and emerge but have not yet reached levels supportive of a diagnosis
Neuroprotective effect of mild hypothermia in patients undergoing coronary artery surgery with cardiopulmonary bypass: Five-year follow-up of a randomized trial
ObjectiveIn a randomized trial of 223 patients undergoing coronary artery surgery with cardiopulmonary bypass, we have reported a neuroprotective effect of mild hypothermia. To determine whether the beneficial effect of mild hypothermia was long-lasting, we repeated the psychometric tests in 131 patients after 5 years.MethodsPatients were cooled to 32°C during aortic crossclamping and then randomized to rewarming to either 34°C or 37°C, with no further rewarming until arrival in intensive care unit. Cognitive function was measured preoperatively and 1 week and 5 years postoperatively with a battery of 11 psychometric tests interrogating verbal memory, attention, and psychomotor speed and dexterity.ResultsPatients who had greater cognitive decline 1 week after surgery showed poorer performance 5 years later. The magnitude of cognitive decline over 5 years was modest. The incidence of deficits defined as a 1 standard deviation [SD] decline in at least 1 of 3 factors was not different between temperature groups. Fewer patients in the hypothermic group had deficits that persisted over the 5 years, but this difference did not attain statistical significance (RR = 0.64, P = .16).ConclusionsThe effect of surgery on cognitive function observed early after surgery is an important predictor of cognitive performance 5 years later. Although there was evidence of a neuroprotective effect of mild hypothermia early after surgery in the original cohort, the results after 5 years were inconclusive. In general, the magnitude of cognitive changes over 5 years was modest. We believe that further trials investigating the efficacy of mild hypothermia in patients having cardiac surgery are warranted
Anesthesiologists' and surgeons' perceptions about routine pre-operative testing in low risk patients: application of the Theoretical Domains Framework to identify factors that influence physicians' decisions to order pre-operative tests
Background
Routine pre-operative tests for anesthesia management are often ordered by both anesthesiologists and surgeons for healthy patients undergoing low-risk surgery. The Theoretical Domains Framework (TDF) was developed to investigate determinants of behaviour and identify potential behaviour change interventions. In this study, the TDF is used to explore anaesthesiologistsâ and surgeonsâ perceptions of ordering routine tests for healthy patients undergoing low-risk surgery.
Conclusion
We identified key factors that anesthesiologists and surgeons believe influence whether they order pre-operative tests routinely for anesthesia management for a healthy adults undergoing low-risk surgery. These beliefs identify potential individual, team, and organisation targets for behaviour change interventions to reduce unnecessary routine test ordering.
Methods
Sixteen clinicians (eleven anesthesiologists and five surgeons) throughout Ontario were recruited. An interview guide based on the TDF was developed to identify beliefs about preoperative testing practices. Content analysis of physiciansâ statements into the relevant theoretical domains was performed. Specific beliefs were identified by grouping similar utterances of the interview participants. Relevant domains were identified by noting the frequencies of the beliefs reported, presence of conflicting beliefs, and perceived influence on the performance of the behaviour under investigation.
Results
Seven of the twelve domains were identified as likely relevant to changing cliniciansâ behaviour about pre-operative test ordering for anesthesia management. Key beliefs were identified within these domains including: conflicting comments about who was responsible for the test-ordering (Social/professional role and identity); inability to cancel tests ordered by fellow physicians (Beliefs about capabilities and social influences); and the problem with tests being completed before the anesthesiologists see the patient (Beliefs about capabilities and Environmental context and resources). Often, tests were ordered by an anesthesiologist based on who may be the attending anesthesiologist on the day of surgery while surgeons ordered tests they thought anesthesiologists may need (Social influences). There were also conflicting comments about the potential consequences associated with reducing testing, from negative (delay or cancel patientsâ surgeries), to indifference (little or no change in patient outcomes), to positive (save money, avoid unnecessary investigations) (Beliefs about consequences). Further, while most agreed that they are motivated to reduce ordering unnecessary tests (Motivation and goals), there was still a report of a gap between their motivation and practice (Behavioural regulation)
Beneficial autoimmunity at body surfaces â immune surveillance and rapid type 2 immunity regulate tissue homeostasis and cancer
Epithelial cells line body surface tissues and provide a physicochemical barrier to the external environment. Frequent microbial and non-microbial challenges such as those imposed by mechanical disruption, injury or exposure to noxious environmental substances including chemicals, carcinogens, ultraviolet-irradiation or toxins cause activation of epithelial cells with release of cytokines and chemokines as well as alterations in the expression of cell surface ligands. Such display of epithelial stress is rapidly sensed by tissue resident immunocytes, which can directly interact with self-moieties on epithelial cells and initiate both local and systemic immune responses. Epithelial cells are thus key drivers of immune surveillance at body surface tissues. However, epithelial cells have a propensity to drive type 2 immunity (rather than type 1) upon non-invasive challenge or stress â a type of immunity whose regulation and function still remain enigmatic. Here we review the induction and possible role of type 2 immunity in epithelial tissues and propose that rapid immune surveillance and type 2 immunity are key regulators of tissue homeostasis and carcinogenesis
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