Measurements of the Electric Form Factor of the Neutron up to Q(2)=3.4 GeV2 Using the Reaction (3)(He)over-right-arrowe((e)over-right-arrow, e \u27 n)pp

The electric form factor of the neutron was determined from studies of the reaction 3He⃗(e⃗,e′n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find GEn=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q2=1.72, 2.48, and 3.41  GeV2, respectively

Search for a New Gauge Boson in Electron-Nucleus Fixed-Target Scattering by the APEX Experiment

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α′ to electrons. Such a particle A′ can be produced in electron-nucleus fixed-target scattering and then decay to an e+e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175–250 MeV, found no evidence for an A′→e+e- reaction, and set an upper limit of α′/α≃10-6. Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces

Measurement of the Neutron Radius of (208)Pb through Parity Violation in Electron Scattering

We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV=0.656±0.060(stat)±0.014(syst)  ppm corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp=0.33-0.18+0.16  fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus

Adjusting Overall Survival Estimates after Treatment Switching: a Case Study in Metastatic Castration-Resistant Prostate Cancer

Background If patients in oncology trials receive subsequent therapy, standard intention-to-treat (ITT) analyses may inaccurately estimate the overall survival (OS) effect of the investigational product. In this context, a post-hoc analysis of the phase 3 PREVAIL study was performed with the aim to compare enzalutamide with placebo in terms of OS, adjusting for potential confounding from switching to antineoplastic therapies that are not part of standard metastatic castration-resistant prostate cancer (mCRPC) treatment pathways in some jurisdictions. Methods The PREVAIL study, which included 1717 chemotherapy-naïve men with mCRPC randomized to treatment with enzalutamide 160 mg/day or placebo, was stopped after a planned interim survival analysis revealed a benefit in favor of enzalutamide. Data from this cutoff point were confounded by switching from both arms and so were evaluated in terms of OS using two switching adjustment methods: the two-stage accelerated failure time model (two-stage method) and inverse probability of censoring weights (IPCW). Results Following adjustment for switching to nonstandard antineoplastic therapies by 14.8 (129/872 patients) and 21.3% (180/845 patients) of patients initially randomized to enzalutamide and placebo, respectively, the two-stage and IPCW methods both resulted in numerical reductions in the hazard ratio (HR) for OS [HR 0.66, 95% confidence interval (CI) 0.57–0.81 and HR 0.63, 95% CI 0.52–0.75, respectively] for enzalutamide compared to placebo versus the unadjusted ITT analysis (HR 0.71, 95% CI 0.60–0.84). These results suggest a slightly greater effect of enzalutamide on OS than originally reported. Conclusion In the PREVAIL study, switching to nonstandard antineoplastic mCRPC therapies resulted in the ITT analysis of primary data underestimating the benefit of enzalutamide on OS

Cracks in GaN/AlN multiple quantum well structures grown by MBE

Due to the large lattice constant mismatch and thermal expansion coefficient difference between GaN and AlN, large strain is generated inside the GaN/AlN multiple quantum wells, which causes cracks in the structure. We investigated such cracks by optical microscopy and AFM. The crack density was studied with buffer and cap layer thickness, the number of quantum well periods, and the temperature reduction rate after growth as parameters. It was found that the crack density increased exponentially, with the number of periods above 4. Besides, a very thin, 100 nm, GaN buffer layer and similar to 300 nm GaN cap layer greatly reduced the crack density

Improving organizational learning through leadership training

Purpose: Managers play a crucial role in providing opportunities to employees for learning. Although scholars have called for intervention research on the effects of leadership development on organizational learning, no such research is currently available. This paper evaluates whether training of managers at workplaces can improve organizational learning. Methodology: The training program consisted of theoretical and practical elements aimed to improve line managers’ transformational leadership behaviors and, in turn, improve organizational learning. The study used a pre- and post-intervention evaluation survey. Line managers’ and their subordinates' perceptions of organizational learning were measured with the Dimensions of Organizational Learning Questionnaire and with post-intervention single items on organizational learning. Findings: Comparisons between pre-and post-intervention assessments revealed that managers’ ratings of Continuous Learning and employees' ratings of Empowerment and Embedded Systems improved significantly as a result of the training. The leadership training intervention had positive effects on managers' perceptions of individual-level and on employees' perceptions of organizational-level aspects of organizational learning. Originality/value: The study provides empirical evidence that organizational learning can be improved through leadership training. Both line managers and their subordinates perceived that organizational learning had increased after the training intervention, albeit in different ways. Implications for developing leadership training programs and for evaluating these are discussed

The Fear of Exclusion: Individual Effort when Group Formation is Endogenous

To secure their membership in a popular group, individuals may contribute more to the group’s local public good than they would if group formation were exogenous. Those in the most unpopular group do not have this incentive to contribute to their group. Substantial differences in individual efforts levels between groups may be the result. A principal may prefer either exogenous or endogenous group formation, depending on whether an increase in contributions to the local public good coincides with the principal’s interests. We analyze two examples: Social interaction in schools, and multiple-task teamwork

Ions Accelerated by Sounder-Plasma Interaction as Observed by Mars Express

The ion sensor of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment detects accelerated ions during pulses of radio emissions from the powerful topside sounder: the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) onboard Mars Express. Accelerated ions (O+2, O+, and lighter ions) are observed in an energy range up to 800 eV when MARSIS transmits at a frequency close to the plasma frequency. Individual observations consist of almost monoenergetic ion beams aligned with the MARSIS antenna or lying in the plane perpendicular to the antenna. The observed ion beams are often accompanied by a small decrease in the electron flux observed by the electron sensor of Analyzer of Space Plasmas and Energetic Atoms 3. Observations indicate that the voltage applied to the antenna causes charging of the spacecraft to several hundreds of volts by the electrons of the ambient plasma. Positively charged ions are accelerated when the spacecraft discharges