Development of a prototype automatic controller for liquid cooling garment inlet temperature

The development of a computer control of a liquid cooled garment (LCG) inlet temperature is descirbed. An adaptive model of the LCG is used to predict the heat-removal rates for various inlet temperatures. An experimental system that contains a microcomputer was constructed. The LCG inlet and outlet temperatures and the heat exchanger outlet temperature form the inputs to the computer. The adaptive model prediction method of control is successful during tests where the inlet temperature is automatically chosen by the computer. It is concluded that the program can be implemented in a microprocessor of a size that is practical for a life support back-pack

Unsteady Simulations of Rocket Plume Expansions in Geostationary Earth Orbit

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143086/1/1.A33838.pd

Role of oxygen in the electron-doped superconducting cuprates

We report on resistivity and Hall measurements in thin films of the electron-doped superconducting cuprate Pr$_{2-x}$Ce$_{x}$CuO$_{4\pm\delta}$. Comparisons between x = 0.17 samples subjected to either ion-irradiation or oxygenation demonstrate that changing the oxygen content has two separable effects: 1) a doping effect similar to that of cerium, and 2) a disorder effect. These results are consistent with prior speculations that apical oxygen removal is necessary to achieve superconductivity in this compound.Comment: 5 pages, 5 figure

Gaining clinical wisdom from adversity: Nurse leaders’ ethical conflict and resilience experiences

Developing effective nurse leaders in today’s“reengineered” corporate healthcare cultures requires that more attention be given to the preparation of ethical leadership during undergraduate programs and nurses’ formative years in practice. Through analyzing the experiences of three nurse leaders dealing with ethical conflicts and the meaning they made of these experiences, we identified that nurses need practical guidance to successfully negotiate ethical conflicts, take risks to uphold their ethical codes, and foster collaborative relationships. According to these nurse leaders, it was important to mentor student and novice nurses in working through workplace ethical conflicts and help guide them through the formulation of successful practical strategies. Our findings showed that these nurses developed resilience and clinical wisdom which they carried through to their leadership practice and future situations

The Singularity in Generic Gravitational Collapse Is Spacelike, Local, and Oscillatory

A longstanding conjecture by Belinskii, Khalatnikov, and Lifshitz that the singularity in generic gravitational collapse is spacelike, local, and oscillatory is explored analytically and numerically in spatially inhomogeneous cosmological spacetimes. With a convenient choice of variables, it can be seen analytically how nonlinear terms in Einstein's equations control the approach to the singularity and cause oscillatory behavior. The analytic picture requires the drastic assumption that each spatial point evolves toward the singularity as an independent spatially homogeneous universe. In every case, detailed numerical simulations of the full Einstein evolution equations support this assumption.Comment: 7 pages includes 4 figures. Uses Revtex and psfig. Received "honorable mention" in 1998 Gravity Research Foundation essay contest. Submitted to Mod. Phys. Lett.

Ion-channel-like behavior in lipid bilayer membranes at the melting transition

It is well known that at the gel-liquid phase transition temperature a lipid bilayer membrane exhibits an increased ion permeability. We analyze the quantized currents in which the increased permeability presents itself. The open time histogram shows a "-3/2" power law which implies an open-closed transition rate that decreases like $k(t) \propto t^{-1}$ as time evolves. We propose a "pore freezing" model to explain the observations. We discuss how this model also leads to the $1/f^{\alpha}$ noise that is commonly observed in currents across biological and artificial membranes.Comment: 5 pages, 4 figure

High velocity spikes in Gowdy spacetimes

We study the behavior of spiky features in Gowdy spacetimes. Spikes with velocity initially high are, generally, driven to low velocity. Let n be any integer greater than or equal to 1. If the initial velocity of an upward pointing spike is between 4n-3 and 4n-1 the spike persists with final velocity between 1 and 2, while if the initial velocity is between 4n-1 and 4n+1, the spiky feature eventually disappears. For downward pointing spikes the analogous rule is that spikes with initial velocity between 4n-4 and 4n-2 persist with final velocity between 0 and 1, while spikes with initial velocity between 4n-2 and 4n eventually disappear.Comment: discussion of constraints added. Accepted for publication in Phys. Rev.

Probing the mechanical properties of graphene using a corrugated elastic substrate

The exceptional mechanical properties of graphene have made it attractive for nano-mechanical devices and functional composite materials. Two key aspects of graphene's mechanical behavior are its elastic and adhesive properties. These are generally determined in separate experiments, and it is moreover typically difficult to extract parameters for adhesion. In addition, the mechanical interplay between graphene and other elastic materials has not been well studied. Here, we demonstrate a technique for studying both the elastic and adhesive properties of few-layer graphene (FLG) by placing it on deformable, micro-corrugated substrates. By measuring deformations of the composite graphene-substrate structures, and developing a related linear elasticity theory, we are able to extract information about graphene's bending rigidity, adhesion, critical stress for interlayer sliding, and sample-dependent tension. The results are relevant to graphene-based mechanical and electronic devices, and to the use of graphene in composite, flexible, and strain-engineered materials.Comment: 5 pages, 4 figure

Manufacture of Gowdy spacetimes with spikes

In numerical studies of Gowdy spacetimes evidence has been found for the development of localized features (spikes) involving large gradients near the singularity. The rigorous mathematical results available up to now did not cover this kind of situation. In this work we show the existence of large classes of Gowdy spacetimes exhibiting features of the kind discovered numerically. These spacetimes are constructed by applying certain transformations to previously known spacetimes without spikes. It is possible to control the behaviour of the Kretschmann scalar near the singularity in detail. This curvature invariant is found to blow up in a way which is non-uniform near the spike in some cases. When this happens it demonstrates that the spike is a geometrically invariant feature and not an artefact of the choice of variables used to parametrize the metric. We also identify another class of spikes which are artefacts. The spikes produced by our method are compared with the results of numerical and heuristic analyses of the same situation.Comment: 25 page

Hydrogen Isocyanide in Comet 73P/Schwassmann-Wachmann (Fragment B)

We present a sensitive 3-sigma upper limit of 1.1% for the HNC/HCN abundance ratio in comet 73P/Schwassmann-Wachmann (Fragment B), obtained on May 10-11, 2006 using Caltech Submillimeter Observatory (CSO). This limit is a factor of ~7 lower than the values measured previously in moderately active comets at 1 AU from the Sun. Comet 73P/Schwassmann-Wachmann was depleted in most volatile species, except of HCN. The low HNC/HCN ratio thus argues against HNC production from polymers produced from HCN. However, thermal degradation of macromolecules, or polymers, produced from ammonia and carbon compounds, such as acetylene, methane, or ethane appears a plausible explanation for the observed variations of the HNC/HCN ratio in moderately active comets, including the very low ratio in comet 73P/Schwassmann-Wachmann reported here. Similar polymers have been invoked previously to explain anomalous 14N/15N ratios measured in cometary CN.Comment: 6 pages, 5 figures, 2 table