Ceiling and visibility instrumentation within government agencies

The key systems requirements for ceilometer systems are described. The following items are included: range must be 10,000 ft.; laser emission must conform to the bureau of radiological health class I performance; system must detect two lowest cloud layers; display must be in either English or metric units; and system must be capable of self monitoring and testing performance. Based upon the requirements competitive prototype cloud height indicator systems are to be built

Studies of the physiology, pharmacology, and biochemistry of the auxins

Several excellent reviews of auxin matters have appeared during the past few years dealing broadly with the subject as a whole, such as the Wisconsin Symposium on Plant Growth Substances whleh is referred to repeatedly below, as well as reviews of more restricted scope such as those of Thimann (116) and of the previous volumes in this series. The present review need not, therefore, attempt to cover the entire spectrum of auxin physiology. It will concern a few aspects of the subject only, aspects in which particular progress has been made in recent years. It will attempt to evaluate the work which has been done in each of the several fields, to see in how far an integrated picture can be made of each and to make a few suggestions

Total Chiral Symmetry Breaking during Crystallization: Who needs a "Mother Crystal"?

Processes that can produce states of broken chiral symmetry are of particular interest to physics, chemistry and biology. Chiral symmetry breaking during crystallization of sodium chlorate occurs via the production of secondary crystals of the same handedness from a single "mother crystal" that seeds the solution. Here we report that a large and "symmetric" population of D- and L-crystals moves into complete chiral purity disappearing one of the enantiomers. This result shows: (i) a new symmetry breaking process incompatible with the hypothesis of a single "mother crystal"; (ii) that complete symmetry breaking and chiral purity can be achieved from an initial system with both enantiomers. These findings demand a new explanation to the process of total symmetry breaking in crystallization without the intervention of a "mother crystal" and open the debate on this fascinating phenomenon. We present arguments to show that our experimental data can been explained with a new model of "complete chiral purity induced by nonlinear autocatalysis and recycling".Comment: 5 pages, 4 figures, Added reference

Superparamagnetic-like ac susceptibility behavior in a "partially disordered antiferromagnetic" compound, Ca3_3CoRhO6_6

We report the results of dc and ac magnetization measurements as a function of temperature (1.8 - 300 K) for the spin chain compound, Ca$_3$CoRhO$_6$, which has been recently reported to exhibit a partially disordered antiferromagnetic (PDAF) structure in the range 30 - 90 K and spin-glass freezing below 30 K. We observe an unexpectedly large frequency dependence of ac susceptibility in the T range 30 - 90 K, typical of superparamagnets. In addition, we find that there is no difference in the isothermal remanent magnetization behavior for the two regimes below 90 K. These findings call for more investigations to understand the magnetism of this compound.Comment: 4 pages, 3 figure

A Reanalysis of the Hydrodynamic Theory of Fluid, Polar-Ordered Flocks

I reanalyze the hydrodynamic theory of fluid, polar ordered flocks. I find new linear terms in the hydrodynamic equations which slightly modify the anisotropy, but not the scaling, of the damping of sound modes. I also find that the nonlinearities allowed {\it in equilibrium} do not stabilize long ranged order in spatial dimensions $d=2$; in accord with the Mermin-Wagner theorem. Nonequilibrium nonlinearities {\it do} stabilize long ranged order in $d=2$, as argued by earlier work. Some of these were missed by earlier work; it is unclear whether or not they change the scaling exponents in $d=2$.Comment: 6 pages, no figures. arXiv admin note: text overlap with arXiv:0909.195

Black hole solutions in 2+1 dimensions

We give circularly symmetric solutions for null fluid collapse in 2+1-dimensional Einstein gravity with a cosmological constant. The fluid pressure $P$ and energy density $\rho$ are related by $P=k\rho$ $(k\le 1)$. The long time limit of the solutions are black holes whose horizon structures depend on the value of $k$. The $k=1$ solution is the Banados-Teitelboim-Zanelli black hole metric in the long time static limit, while the $k<1$ solutions give other, `hairy' black hole metrics in this limit.Comment: 8 pages, RevTeX (to appear in Phys. Rev. D) References to Mann and Ross, and Mann, Chan and Chan adde

Covariantes continuas individuales dependientes del tiempo y el modelo de Cormack–Jolly–Seber

The Cormack–Jolly–Seber model provides the basic framework for analyzing the survival of animals in open populations using capture–recapture data. Extensions of this model have already been developed that allow the survival and capture probabilities to vary between individuals based on auxiliary variables, but none can allow for variables that are continuous, time–dependent, and vary among individuals. We summarize a new method for incorporating this type of variable into the Cormack–Jolly–Seber model by modelling the distribution of the unobserved values of the variable conditional on the observed values, given a few basic assumptions about how the variable changes over time. We begin with a hypothetical scenario as motivation for our model and also present the results of two examples used in developing the model.El modelo de Cormack–Jolly–Seber proporciona el marco básico para analizar la supervivencia de animales en poblaciones abiertas utilizando datos de captura–recaptura. Si bien se han desarrollado ampliaciones de este modelo que permiten variar las probabilidades de supervivencia y de captura entre individuos a partir de variables auxiliares, en ninguna de ellas es posible utilizar variables continuas, dependientes del tiempo y que varíen de un individuo a otro. El presente estudio analiza un nuevo método que permite la incorporación de este tipo de variable en el modelo de Cormack–Jolly–Seber mediante la modelación de la distribución de los valores no observados de la variable según los valores observados, tomando como referencia algunas asumciones básicas acerca de cómo la variable cambia con el tiempo. En primer lugar, presentamos un escenario hipotético con objeto de definir el modelo, para posteriormente indicar los resultados de dos ejemplos que utilizamos para su desarrollo

Somatostatin: Diverse Physiological Roles and Therapeutic Implications

In its brief lifetime as a known peptide, somatostatin has provided a truly remarkable story filled with surprising developments from unexpected quarters. The foundation was set in 1969, when Krulich and McCann reported that fractions of a crude hypothalamic extract inhibited the secretion of growth hormone. In 1973, Guillemin\u27s laboratory reported the sequence and synthesis of a fourteen amino acid peptide with the same inhibitory effect. It occurs in both a cyclic and linear form, each displaying equal biological activity. Somatostatin was assigned as its name, but it is also commonly referred to as growth hormone release inhibitory factor (GHRIF) or somatotropin-release inhibiting factor (SRIF)