317 research outputs found
Spin content of constituent quarks and one-spin asymmetries in inclusive processes
We consider mechanism for one-spin asymmetries observed in inclusive hadron
production. The main role belongs to the orbital angular momentum of the
quark-antiquark cloud in the internal structure of constituent quarks. We argue
that the origin of the asymmetries in pion production is a result of retaining
of this internal angular orbital momentum by the perturbative phase of QCD
under transition from the non-perturbative phase. The non-perturbative hadron
structure is based on the results of chiral quark models. PACS number(s):
11.30.Qc, 12.40.Pp, 13.75.Ni, 13.88.+eComment: 21 pages LaTeX + 8 figures (not included
Search for Direct CP Violation in Non-Leptonic Decays of Charged and Hyperons
A search for direct CP violation in the non-leptonic decays of hyperons has
been performed. In comparing the product of the decay parameters,
, in terms of an asymmetry parameter,
, between hyperons and anti-hyperons in the charged and decay sequence, we found no evidence of
direct CP violations. The parameter was measured to be .Comment: Submitted for publication; RevTex, 13 pages, 4 figure
Hyperon Polarization in the Constituent Quark Model
We consider mechanism for hyperon polarization in inclusive production. The
main role belongs to the orbital angular momentum and polarization of the
strange quark-antiquark pairs in the internal structure of the constituent
quarks. We consider a nucleon as a core consisting of the constituent quarks
embedded into quark condensate. The nonperturbative hadron structure is based
on the results of chiral quark models.Comment: 14 pages, LaTeX, 2 Figures, References adde
Genitourinary Tuberculosis: A Rare Cause of Obstructive Uropathy in Pregnancy
Background. A rare but morbid form of extrapulmonary tuberculosis (TB), genitourinary TB is an important cause of obstructive uropathy and is likely underdiagnosed in pregnancy. Case. A 30-year-old primigravida undergoing treatment for active pulmonary TB presented with anuria at 13-14-weeks gestation. Bilateral ureteral strictures above the level of the ureterovesicular junctions were seen on imaging studies. Given her pulmonary disease, her obstructive uropathy was attributed to genitourinary TB. Bilateral percutaneous nephrostomy tubes were placed during pregnancy with successful ureteral reimplantation postpartum. Conclusion. Genitourinary TB should be considered as an etiology of urinary tract pathology during pregnancy, especially in foreign-born and immunocompromised persons. Early recognition resulting in prompt treatment can prevent further deterioration of maternal renal function and optimize pregnancy outcomes
Human Capital Policies: What They Can and Cannot Do for Productivity and Poverty Reduction in Latin America
Raising labor productivity is recognized as a critical factor for increasing economic growth and reducing poverty levels in Latin America. Low levels of education continue to be singled out as the main obstacle to higher productivity in the region. We examine the scope for education to lift labor incomes above poverty levels in Latin America and find that in many countries education, by itself, has a positive, but limited, potential to increase wages above a minimum level. In general, the prospects are dim because progress in raising average schooling levels has been slow even under the best historical scenarios. We also examine whether the apparent failure of education can be explained by low wage returns to schooling, and poor underlying conditions. We find that investments in education continue to have important payoffs but poor underlying conditions explain the modest prospect for the role of education in the short run. This leads us to consider what additional policies should be pursued in order to ensure higher productivity for workers in the region
The Impact of Alcohol-Specific and Traditional Masculine Norms on Drinking Game Behaviors: A Multisite Study of Emerging Adult Men
Playing a drinking game (DG) can provide a context for men to behave in accordance with endorsed masculine norms. Using a multisite college sample of emerging adult men ( n = 1142), we examined alcohol-specific masculine norms ( excess / control ) alongside traditional masculine norms and their relations to DG frequency and quantity, and the moderating effects of fraternity membership and hazardous drinking status on these associations. After adjusting for known demographic correlates of DG behaviors and non-DG-related alcohol use, we found that the masculine drinking norm of excess was positively associated with DG frequency, with the effect being primarily driven by this association among fraternity men. Excess was unrelated to DG quantity when accounting for covariates. Control was negatively associated with DG frequency but was unrelated to DG quantity; neither fraternity membership nor hazardous drinking status moderated these associations. Our findings further our theoretical understanding of how masculinity relates to DG behaviors among emerging adults
Strength Training for Arthritis Trial (START): design and rationale
Background Muscle loss and fat gain contribute to the disability, pain, and morbidity associated with knee osteoarthritis (OA), and thigh muscle weakness is an independent and modifiable risk factor for it. However, while all published treatment guidelines recommend muscle strengthening exercise to combat loss of muscle mass and strength in knee OA patients, previous strength training studies either used intensities or loads below recommended levels for healthy adults or were generally short, lasting only 6 to 24 weeks. The efficacy of high-intensity strength training in improving OA symptoms, slowing progression, and affecting the underlying mechanisms has not been examined due to the unsubstantiated belief that it might exacerbate symptoms. We hypothesize that in addition to short-term clinical benefits, combining greater duration with high-intensity strength training will alter thigh composition sufficiently to attain long-term reductions in knee-joint forces, lower pain levels, decrease inflammatory cytokines, and slow OA progression. Methods/Design This is an assessor-blind, randomized controlled trial. The study population consists of 372 older (age ≥ 55 yrs) ambulatory, community-dwelling persons with: (1) mild-to-moderate medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2 or 3); (2) knee neutral or varus aligned knee ( -2° valgus ≤ angle ≤ 10° varus); (3) 20 kg.m-2 ≥ BMI ≤ 45 kg.m-2; and (3) no participation in a formal strength-training program for more than 30 minutes per week within the past 6 months. Participants are randomized to one of 3 groups: high-intensity strength training (75-90% 1Repetition Maximum (1RM)); low-intensity strength training (30-40%1RM); or healthy living education. The primary clinical aim is to compare the interventions’ effects on knee pain, and the primary mechanistic aim is to compare their effects on knee-joint compressive forces during walking, a mechanism that affects the OA disease pathway. Secondary aims will compare the interventions’ effects on additional clinical measures of disease severity (e.g., function, mobility); disease progression measured by x-ray; thigh muscle and fat volume, measured by computed tomography (CT); components of thigh muscle function, including hip abductor strength and quadriceps strength, and power; additional measures of knee-joint loading; inflammatory and OA biomarkers; and health-related quality of life. Discussion Test-retest reliability for the thigh CT scan was: total thigh volume, intra-class correlation coefficients (ICC) = 0.99; total fat volume, ICC = 0.99, and total muscle volume, ICC = 0.99. ICC for both isokinetic concentric knee flexion and extension strength was 0.93, and for hip-abductor concentric strength was 0.99. The reliability of our 1RM testing was: leg press, ICC = 0.95; leg curl, ICC = 0.99; and leg extension, ICC = 0.98. Results of this trial will provide critically needed guidance for clinicians in a variety of health professions who prescribe and oversee treatment and prevention of OA-related complications. Given the prevalence and impact of OA and the widespread availability of this intervention, assessing the efficacy of optimal strength training has the potential for immediate and vital clinical impact
Performance Comparison of 10 State-of-the-Art Machine Learning Algorithms for Outcome Prediction Modeling of Radiation-Induced Toxicity
Purpose: To evaluate the efficacy of prominent machine learning algorithms in predicting normal tissue complication probability using clinical data obtained from 2 distinct disease sites and to create a software tool that facilitates the automatic determination of the optimal algorithm to model any given labeled data set.
Methods and materials: We obtained 3 sets of radiation toxicity data (478 patients) from our clinic: gastrointestinal toxicity, radiation pneumonitis, and radiation esophagitis. These data comprised clinicopathological and dosimetric information for patients diagnosed with non-small cell lung cancer and anal squamous cell carcinoma. Each data set was modeled using 11 commonly employed machine learning algorithms (elastic net, least absolute shrinkage and selection operator [LASSO], random forest, random forest regression, support vector machine, extreme gradient boosting, light gradient boosting machine, k-nearest neighbors, neural network, Bayesian-LASSO, and Bayesian neural network) by randomly dividing the data set into a training and test set. The training set was used to create and tune the model, and the test set served to assess it by calculating performance metrics. This process was repeated 100 times by each algorithm for each data set. Figures were generated to visually compare the performance of the algorithms. A graphical user interface was developed to automate this whole process.
Results: LASSO achieved the highest area under the precision-recall curve (0.807 ± 0.067) for radiation esophagitis, random forest for gastrointestinal toxicity (0.726 ± 0.096), and the neural network for radiation pneumonitis (0.878 ± 0.060). The area under the curve was 0.754 ± 0.069, 0.889 ± 0.043, and 0.905 ± 0.045, respectively. The graphical user interface was used to compare all algorithms for each data set automatically. When averaging the area under the precision-recall curve across all toxicities, Bayesian-LASSO was the best model.
Conclusions: Our results show that there is no best algorithm for all data sets. Therefore, it is important to compare multiple algorithms when training an outcome prediction model on a new data set. The graphical user interface created for this study automatically compares the performance of these 11 algorithms for any data set
Preliminary results from E756 on the Ξ− and Ω− magnetic moments
We have used the spin precession technique to measure the Ξ− and Ω− magnetic moments. The preliminary results are μ(Ξ−)=−0.64±0.02 nuclear magnetons and μ(Ω−)=−2.0±0.2 nuclear magnetons where the error for both measurements is statistical. The polarization of Ξ−’s produced at 2.5 mr by 800 GeV protons on a Be target was 11% while the polarization of Ω−’s was consistent with zero. Polarized Ξ−’s and Ω−’s were produced using spin transfer from a polarized neutral hyperon beam. The Ω− polarization at 325 GeV/c was 6.5%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87375/2/374_1.pd
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