1,521 research outputs found

    Precision Tests of Parity Violation Over Cosmological Distances

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    Recent measurements of the Cosmic Microwave Background BB-mode polarization power spectrum by the BICEP2 and POLARBEAR experiments have demonstrated new precision tools for probing fundamental physics. Regardless of origin, the fact that we can detect sub-μ\muK CMB polarization represents a tremendous technological breakthrough. Yet more information may be latent in the CMB's polarization pattern. Because of its tensorial nature, CMB polarization may also reveal parity-violating physics via a detection of cosmic polarization rotation. Although current CMB polarimeters are sensitive enough to measure one degree-level polarization rotation with >5σ>5\sigma statistical significance, they lack the ability to differentiate this effect from a systematic instrumental polarization rotation. Here, we motivate the search for cosmic polarization rotation from current CMB data as well as independent radio galaxy and quasar polarization measurements. We argue that an improvement in calibration accuracy would allow the precise measurement of parity- and Lorentz-violating effects. We describe the CalSat space-based polarization calibrator that will provide stringent control of systematic polarization angle calibration uncertainties to 0.05∘0.05^\circ -- an order of magnitude improvement over current CMB polarization calibrators. CalSat-based calibration could be used with current CMB polarimeters searching for BB-mode polarization, effectively turning them into probes of cosmic parity violation, i.e. without the need to build dedicated instruments.Comment: 11 pages, 3 figure

    Ventilation Loss in the NASA Space Shuttle Crew Protective Garments: Potential for Heat Stress

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    The potential of the National Aeronautics and Space Administration (NASA) S1035 Launch/Entry suit (LES) for producing heat stress in a simulated Space Shuttle cabin environment has been studied. The testing was designed to determine if the NASA S1035 poses a greater threat of inducing heat stress than the NASA S1032. Conditions were designed to simulate an extreme prelaunch situation, with chamber temperatures maintained at dry bulb temperature 27.2 +/- 0.1 C, globe temperature - 27.3 +/- 0.1 C, and wet bulb temperature 21.1 +/- 0.3 C. Four males, aged 28-48, were employed in this study, with three subjects having exposures in all four conditions and the fourth subject exposed to 3 conditions. Test durations in the ventilated (V) and unventilated (UV) conditions were designed for 480 minutes, which all subjects achieved. No significant differences related to experimental conditions were noted in rectal temperatures, heart rates or sweat rates. The results indicate that the S1032 and S1035 garments, in either the V or UV state, poses no danger of inducing unacceptable heat stress under the conditions expected within the Shuttle cabin during launch or re-entry

    State of the Unions: The Impact of Janus on Public University Student Fees

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    In Janus v. American Federation of State, County,and Municipal Employees, Council 31, the U.S.Supreme Court overruled forty-one years of precedentthat had allowed public-sector unions to collectagency-shop fees from nonmembers. The Court ruled thismandatory fee collection unconstitutional as a violationof nonmember First Amendment rights. This decisionmay pose problems for other public entities, such aspublic universities, who also collect mandatory fees thatsupport political speech

    Ventilation loss and pressurization in the NASA launch/entry suit: Potential for heat stress

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    The potential of the NASA Launch/Entry Suit (LES) for producing heat stress in a simulated Space Shuttle cabin environment was studied. The testing was designed to identify potential heat stress hazards if the LES were pressurized or if ventilation were lost. Conditions were designed to simulate an extreme pre-launch situation with chamber temperatures maintained at dry bulb temperature = 27.2 +/- 0.1 C, globe temperature = 27.3 +/- 0.1 C, and wet bulb temperature = 21.1 +/- 0.3 C. Two females and two males, 23 to 34 years of age, were employed in this study, with two subjects having exposures in all 3 conditions. Test durations in the ventilated (V) and unventilated (UV) conditions were designed for 480 minutes, which all subjects achieved. Pressurized runs (Pr) were designed for 45 minutes, which all subjects also achieved. While some significant differences related to experimental conditions were noted in rectal and mean skin temperatures, evaporation rates, sweat rates, and heart rate, these differences were not thought to be physiologically significant. The results indicate that the LES garment, in either the Pr or UV state, poses no danger of inducing unacceptable heat stress under the conditions expected within the Space Shuttle cabin during launch or reentry

    Thinking, Talking and Acting about Public Health Ethics in the COVID-19 Pandemic

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    During the COVID-19 pandemic, the discipline of public ethics has struggled to find a consensus on how best to conceptualise the challenges. The transactional nature of clinical ethics is too limited to capture the range of ethically relevant concerns. Although public health ethics is broader, it fails to provide a convincing framework for the deeply political implications of the response to the pandemic. They go beyond health issues and raise questions of justice. We consider the demands of fairness for all, corrective justice for past structural wrongs, and utopian approaches that draw on our ideas about the ideal society. The lack of an agreed framework for ethical analysis is exacerbated by dwindling faith in expertise and a degradation of trust in media sources to present reliable, accurate information. These matters have undermined the quality of public reason. Although both the USA and UK had well-established anticipatory governance for pandemic influenza, it was not followed when COVID-19 took hold. The pandemic has exposed the weaknesses of our collective thinking, our readiness to discuss the issues rationally and effectively, and our ability to act effectively in the public good. Rebuilding effective public ethics in its wake will present a monumental challenge

    Dude, Where's My Stitch? Strength Analysis of Absorbable Sutures via COMSOL

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    A common method in aiding postoperative tissue healing is the use of a suture, which functions by holding tissues together. The ideal suture is able to lose strength at the same rate that the tissue gains strength. Absorbable sutures have been studied to provide that strength for the tissue, while at the same time reducing tissue trauma caused by the gradual absorption of the biocompatible material. Because of its excellent fiber-forming ability and biodegradability, polyglycolic acid (PGA) has been investigated for developing resorbable sutures [1]. A computational model of the decomposition and mechanical analysis of this suture provided insight into how the mechanical strength of the suture changes as it deteriorates. In this novel study, we aimed to create a model via COMSOL that would simulate the degradation of a dissolvable suture and analyze the sutures changing mechanical properties during degradation. Diffusion of water into the suture occurs so quickly that we realized that bulk erosion, not surface erosion, was the main means of degradation. We created a model that simulated the effect of the natural decomposition of the PGA suture within the body via bulk erosion. By decreasing the volume and applying a uniaxial load to the model, we related the effective Young’s modulus to the original Young’s modulus of the material as the suture degraded. Suture decomposition rate was determined from scientific literature and previous experiments. The suture’s effective elastic modulus decayed with time as the suture dissolved and was absorbed by the body. Knowing the rate at which the elastic modulus decays will allow us to predict the point in time at which the suture no longer holds the tissues together. Findings on the change of material properties of the suture over time are a valuable first step for determining the initial elastic modulus of sutures required for certain tissue repair

    Cauchy interpolation for multi-variate and multi-derivative data

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    There is often a need to interpolate data that is obtained through experiment or computational analysis, because the data is difficult or expensive to obtain. An example is the scattering parameters of microwave devices, obtained through computationally intensive finite element (FE) analysis. Cauchy interpolation is an established solution to this problem. In this thesis it is extended to interpolate data over a multi-parameter space, when the data available includes not just the function to be interpolated, but also its derivatives with respect to each parameter. The finite element method (FEM) provides such derivatives. The new algorithm is applied to a simple RLC circuit test case, and to real data from a 3D FE analysis of a rectangular waveguide component, in a 4-parameter space. Results show the effectiveness of the approach taken

    Evaluation of Self-Perceptions of Creativity: Is It a Useful Criterion?

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    Self-evaluations or self-perceptions of creativity have been used in the past both as predictors of creative performance and as a criterion. Four measures utilizing self-perceptions of creativity were assessed for their usefulness as criterion measures of creativity. Analyses provided evidence of domain specificity of self-perceptions. The scales correlated with self-report measures of creativity, but not with objective measures. Self-perceptions of creativity had strong to moderate relationships with personality and creative self-efficacy. These results suggest that while self-perceptions of creativity may provide some information about creativity, researchers should be cautious when using this measure as a criterion
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