We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = -131 +/- 14(stat) +/- 10(syst) x 10(-9), leading to the ...determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.
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By comparing the cross Sections for left- and right-handed electrons scattered from various unpolarized nuclear targets, the small parity-violating asymmetry can be measured. These asymmetry data ...probe a wide variety of important topies, including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes. A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties, which justifies pushing the experiments to the highest possible precision. To measure the small asymmetries accurately, a number of novel experimental techniques have been developed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
The solenoidal large intensity device (SoLID) is a new experimental apparatus planned for Hall A at the Thomas Jefferson National Accelerator Facility (JLab). SoLID will combine large ...angular and momentum acceptance with the capability to handle very high data rates at high luminosity. With a slate of approved high-impact physics experiments, SoLID will push JLab to a new limit at the QCD intensity frontier that will exploit the full potential of its 12 GeV electron beam. In this paper, we present an overview of the rich physics program that can be realized with SoLID, which encompasses the tomography of the nucleon in 3D momentum space from semi-inclusive deep inelastic scattering, expanding the phase space in the search for new physics and novel hadronic effects in parity-violating DIS, a precision measurement of
J
/
ψ
production at threshold that probes the gluon field and its contribution to the proton mass, tomography of the nucleon in combined coordinate and momentum space with deep exclusive reactions, and more. To meet the challenging requirements, the design of SoLID described here takes full advantage of recent progress in detector, data acquisition and computing technologies. In addition, we outline potential experiments beyond the currently approved program and discuss the physics that could be explored should upgrades of CEBAF become a reality in the future.
We discuss precision measurements of PVDIS with the upgraded JLab 12 GeV beam by using a Solenoidal Łarge Iintensity Device (SoLID). The unique feature of SoLID, combining high luminosity and large ...acceptance, makes it possible to reach the high precision needed to have a high impact by using PVDIS to probe physics beyond the Standard Model. A measurement of PVDIS in deuterium will determine a fundamental coupling constant that is inaccessible with other means. PVDIS measurements can also access a number of topics in QCD physics, including searching for charge symmetry violation in the parton distribution functions, determining the
d
/
u
ratio in the proton without nuclear effects, and a clean extraction of higher-twist effects due to quark-quark correlations. SoLID allows a full exploitation of the physics potential of the JLab 12 GeV upgrade. In addition to PVDIS, it has a set of approved highly-rated experiments to study nucleon transverse spin and transverse structure by using polarized semi-inclusive DIS and to study non-perturbative gluon dynamics with J/
Ψ
production near threshold. A brief description of the SoLID spectrometer is also given.
The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2 = 0.624 GeV2 and beam ...energy E(b) = 3.48 GeV to be A(PV) = -23.80 ± 0.78(stat) ± 0.36(syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors G(E)(s) + 0.517G(M)(s) = 0.003 ± 0.010(stat) ± 0.004(syst) ± 0.009(ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.
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Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that binds environmental toxicants and regulates gene expression. AHR also regulates developmental processes, ...like craniofacial development and hematopoiesis, in the absence of environmental exposures. Zebrafish have 3 paralogs of AHR: ahr1a, ahr1b, and ahr2. Adult zebrafish with mutations in ahr2 exhibited craniofacial and fin defects. However, the degree to which ahr1a and ahr1b influence ahr2 signaling and contribute to fin and craniofacial development are not known. We compared morphology of adult ahr2 mutants and ahr1a;ahr1b single and double mutant zebrafish. We found that ahr1a;ahr1b single and double mutants were morphologically normal whereas ahr2 mutant zebrafish demonstrated fin and craniofacial malformations. At 5 days post fertilization, both ahr1a;ahr1b and ahr2 mutant larvae were normal, suggesting that adult phenotypes are due to defects in maturation or maintenance. Next, we analyzed the function of zebrafish AHRs activated by environmental ligands. The prototypical AHR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), induces toxicity in humans and rodents via AHR and causes cardiotoxicity in zebrafish embryos. It has been shown that embryos with mutations in ahr2 are resistant to TCDD toxicity, yet it is unclear whether ahr1 receptors are required. Furthermore, though AHR was shown to interact with estrogen receptor alpha following TCDD treatment, it is not known whether this interaction is constitutive or context-dependent. To determine whether estrogen receptors are constitutive cofactors for AHR signaling, we used genetic and pharmacologic techniques to analyze TCDD-dependent toxicity in estrogen receptor and ahr mutant embryos. We found that embryos with mutations in ahr1a;ahr1b or estrogen receptor genes are susceptible to TCDD toxicity whereas ahr2 mutant embryos are TCDD-resistant. Moreover, pharmacologic blockade of nuclear estrogen receptors failed to prevent TCDD toxicity. These findings suggest that ahr1 genes do not have overlapping functions with ahr2 in fin and craniofacial development or TCDD-dependent toxicity, and that estrogen receptors are not constitutive partners of ahr2.
We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very ...forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.
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Physician-scientists have long been in high demand owing to their role as key drivers of biomedical innovation, but their dwindling prevalence in research and medical communities threatens ongoing ...progress. As the principal avenue for physician-scientist development, combined MD-PhD training programs and NIH-funded Medical Scientist Training Programs (MSTPs) must address all aspects of career development, including grant writing skills.
The NIH F-series grants - the F30 grant in particular - model the NIH format of federal funding, and are thus ideal opportunities to acquire biomedical research grant preparation experience. Therefore, in this report, we describe a curricular model through which predoctoral MSTP students obtain exposure to - and training for - F-series grant conceptualization, writing, and evaluation.
Since the development of these longitudinal courses, we observed trending improvements in student funding success rates, particularly among original submissions, and perceived benefits among participating students.
During embryonic development, a subset of cells in the mesoderm germ layer are specified as hemato-vascular progenitor cells, which then differentiate into endothelial cells and hematopoietic stem ...and progenitor cells. In zebrafish, the transcription factor npas4l (cloche) is required for the specification of hemato-vascular progenitor cells. However, it is unclear whether npas4l is the sole factor at the top of the hemato-vascular specification cascade. Here, we show that arnt1 and arnt2 genes are required for hemato-vascular specification. We found that arnt1;arnt2 double mutant zebrafish embryos, but not arnt1 or arnt2 single mutants, lack blood cells and most endothelial cells. arnt1/2 mutants have reduced or absent expression of etsrp and tal1, the earliest known endothelial and hematopoietic transcription factor genes. We found that Npas4l binds both Arnt1 and Arnt2 proteins in vitro, consistent with the idea that PAS domain-containing bHLH transcription factors act in a multimeric complex to regulate gene expression. Our results demonstrate that npas4l, arnt1 and arnt2 act together to regulate endothelial and hematopoietic cell fate, where each gene is necessary, but not sufficient, to drive hemato-vascular specification.
OBJECTIVE:Maternal folate (vitamin B9) status is the largest known modifier of neural tube defect risk, so we evaluated folate-related mechanisms of action for dolutegravir (DTG) developmental ...toxicity.
DESIGN:Folate receptor 1 (FOLR1) was examined as a target for DTG developmental toxicity using protein and cellular interaction studies and an animal model.
METHODS:FOLR1 competitive binding studies were used to test DTG for FOLR1 antagonism. Human placenta cell line studies were used to test interactions with DTG, folate, and cations. Zebrafish were selected as an animal model to examine DTG-induced developmental toxicity and rescue strategies.
RESULTS:FOLR1 binding studies indicate DTG is a noncompetitive FOLR1 antagonist at therapeutic concentrations. In-vitro testing indicates calcium (2 mmol/l) increases FOLR1-folate interactions and alters DTG-FOLR1-folate interactions and cytotoxicity. DTG does not inhibit downstream folate metabolism by dihydrofolate reductase. Early embryonic exposure to DTG is developmentally toxic in zebrafish, and supplemental folic acid can mitigate DTG developmental toxicity.
CONCLUSION:Folates and FOLR1 are established modifiers of risk for neural tube defects, and binding data indicates DTG is a partial antagonist of FOLR1. Supplemental folate can ameliorate increased developmental toxicity due to DTG in zebrafish. The results from these studies are expected to inform and guide future animal models and clinical studies of DTG-based antiretroviral therapy in women of childbearing age.
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