Exploring the Expansion History of the Universe

Exploring the recent expansion history of the universe promises insights into the cosmological model, the nature of dark energy, and potentially clues to high energy physics theories and gravitation. We examine the extent to which precision distance-redshift observations can map out the history, including the acceleration-deceleration transition, and the components and equations of state of the energy density. We consider the ability to distinguish between various dynamical scalar field models for the dark energy, as well as higher dimension and alternate gravity theories. Finally, we present a new, advantageous parametrization for the study of dark energy.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Letter

Measured space environmental effects to LDEF during retrieval

On the STS-32 shuttle mission, a space flight experiment provided an understanding of the effects of the space environment on the Long Duration Exposure Facility (LDEF) from rendezvous with the shuttle until removal from the payload bay at the Orbiter Processing Facility (OPF) at KSC. The Interim Operational Contamination Monitor (IOCM) is an attached shuttle payload that has been used on two earlier flights (STS 51C and STS 28) to quantify the contamination deposited during the course of the mission. The IOCM can characterize by direct measurement, the deposition of molecular and particulate contamination during any phase of flight. In addition to these principal measurements, the IOCM actively measures the thermophysical properties of thermal control surfaces by calorimetry, the flux of the ambient atomic oxygen environment, the incident solar flux, and the absolute ambient pressure in the payload bay. The IOCM also provides a structure and sample holders for the exposure of passive material samples to the space environment, e.g. thermal cycling, atomic oxygen, and micrometeoroids and/or orbital debris, etc. One of the more salient results from the STS-32 flight suggests that the LDEF emitted a large number of particulates after berthing into the shuttle. The mission atomic oxygen fluence was also calculated. Although the fluence was low by normal standards, the Kapton passive samples exhibited the onset of erosion. Orbital debris and micrometeoroid impacts also occurred during the retrieval mission. The average perforation diameter was approximately 12.5 microns. The largest perforation diameter was measured at 65 microns

Parametric resonance for antineutrino conversions using LSND best-fit results with a 3+1 flavor scheme

An analytical solution to a parametric resonance effect for antineutrinos in a 3+1 flavor (active+sterile) scheme using multiple non-adiabatic density shifts is presented. We derive the conditions for a full flavor conversion for antineutrino oscillations $\bar{\nu}_\alpha \to \bar{\nu}_s$ $(\alpha=e,\mu,\tau)$ under the assumption that LSND best-fits for the mixing parameters are valid in a short-baseline accelerator experiment. We show that the parametric resonance effect can be exploited to increase the effective antineutrino oscillation length by a factor of 10-40, thus sustaining a high oscillation probability for a much longer period of time than in the vacuum scenario. We propose a realistic experimental setup that could probe for this effect which leaves a signature in terms of a specific oscillation probability profile. Moreover, since the parametric resonance effect is valid in any 2 or 1+1 flavor approximation, our results could be suggestive for future short-baseline accelerator neutrino detection experiments.Comment: 6 pages, 4 figure

Dark Before Light: Testing the Cosmic Expansion History through the Cosmic Microwave Background

The cosmic expansion history proceeds in broad terms from a radiation dominated epoch to matter domination to an accelerated, dark energy dominated epoch. We investigate whether intermittent periods of acceleration are possible in the early universe -- between Big Bang nucleosynthesis (BBN) and recombination and beyond. We establish that the standard picture is remarkably robust: observations of anisotropies in the cosmic microwave background exclude any extra period of accelerated expansion between 1 \leq z \lesssim 10^5 (corresponding to 5\times10^{-4}\ {\rm eV} \leq T \lesssim 25\ {\rm eV}).Comment: 7 pages, 5 figure

Comparison of organoleptic acceptability of liquid and fresh diets

Organoleptic acceptability of liquid and fresh diets for space flight feedin

Use of a single bipolar electrode in the posterior arytenoid muscles for bilateral monitoring of the recurrent laryngeal nerves in thyroid surgery

The aims were to assess the technical feasibility of using a single electrode in the posterior arytenoid muscles (PAM) for intraoperative monitoring of the recurrent laryngeal nerve (RLN) in thyroid surgery, to validate the new method against the insertion of electrodes placed in the vocal cord muscle, and to report the results of the clinical application of the new concept. A total of 52 patients were enrolled. The handling and safety of RLN monitoring was tested by simultaneous registration of the EMG response from vocal fold electrodes and PAM electrodes. Acoustically and electromyographically we found nearly the same values for the arytenoid muscles as for the vocal folds, although the signals taken from the vocal folds were slightly stronger. PAM recording using a single bipolar electrode is technically feasible and as reliable compared to the standard vocal cord monitorin

Reducing Zero-point Systematics in Dark Energy Supernova Experiments

We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission calibration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or space-based.Comment: 30 pages,8 figures, 5 table, one reference added, submitted to Astroparticle Physic

Effects of angiotensin converting enzyme inhibition on endothelial vasodilator function in primary human hypertension

Hypertension in animal models and in humans is associated with a decreased vasodilator response to acetylcholine which causes vascular relaxation by release of endothelium-derived relaxing factor from the endothelium. Since lowering of blood pressure, particularly with angiotensin converting enzyme inhibitors, improved the response to acetylcholine we investigated the effects of brachial artery infusions of ascending dosages of actetylcholine on forearm blood flow before and after 5 months of therapy with the angiotensin converting enzyme inhibitor, cilazapril, in 10 patients with mild to moderate primary hypertension. Cilazapril decreased blood pressure from 150.8 ± 14.4/98.9 ± 4.3 mmHg during placebo to 138.8 ± 15.6/88.6 ± 8.9 mmHg (P < 0.01). Brachial artery acetylcholine infusions increased forearm blood flow from 2.95 ± 1.5 to a maximum of 22.8 ± 11.5 ml.min−1.100 ml−1 forearm tissue and decreased forearm vascular resistance from 48.1 ± 34.1 to 6.9 ± 6.9 units before cilazapril. This response did not change after cilazapril therapy. Our findings in patients with primary hypertension, therefore, do not support the concept that angiotensin converting enzyme inhibition influences endothelium-dependent vascular relaxation to acetylcholine to a significant degree. Whether this lack of effect on endothelial vasodilator function is specific for the vascular bed chosen for study or whether it represents a fundamental difference between animal models and human hypertension remains an important issue to be clarifie