First order effects of production on the continuum theory of spherical electrostatic probes

First order effects of production on continuum theory of spherical Langmuir probes in infinite, homogeneous, slightly ionized, collision-dominated plasm

Information Flow in an R and D Laboratory

Statistical analysis of hypotheses concerning roles of technological gatekeeper and primary groups in flow of information in small research and development laborator

An instability criterion for a finite amplitude localized disturbance in a shear flow of electrically conducting fluids

The stability of shear flows of electrically conducting fluids, with respect to finite amplitude three-dimensional localized disturbances is considered. The time evolution of the fluid impulse integral, characterizing such disturbances, for the case of low magnetic Reynolds number is obtained by integrating analytically the vorticity equation. Analysis of the resulted equation reveals a new instability criterion.Comment: 10 pages in LaTex, no figures, accepted in Phys. Fluid

An improved lower bound for (1,<=2)-identifying codes in the king grid

We call a subset $C$ of vertices of a graph $G$ a $(1,\leq \ell)$-identifying code if for all subsets $X$ of vertices with size at most $\ell$, the sets $\{c\in C |\exists u \in X, d(u,c)\leq 1\}$ are distinct. The concept of identifying codes was introduced in 1998 by Karpovsky, Chakrabarty and Levitin. Identifying codes have been studied in various grids. In particular, it has been shown that there exists a $(1,\leq 2)$-identifying code in the king grid with density 3/7 and that there are no such identifying codes with density smaller than 5/12. Using a suitable frame and a discharging procedure, we improve the lower bound by showing that any $(1,\leq 2)$-identifying code of the king grid has density at least 47/111

Problems of Technical Cooperation in Educational Research: reflections on a Colombian/Dutch research programme

SUMMARY This article is a sub|ective assessment by the Dutch researchers in a collaborative project It describes the chronology, and comments on relationships between Dutch and Colombian project coordinators, research staff, and donors. Finally it comments on expectations about the research output and what the costs and mechanisms of the actual output were. RESUMEN Problemas de cooperación técnica en la investigación educacional: reflexiones sobre un programa de investigación colombiano?holandés Este artículo constituye una apreciación subjetiva de los investigadores holandeses en un proyecto bilateral Describe la cronología y comenta las relaciones entre los coordinadores del proyecto de ambos países, del equipo de investigación y los donantes. Finalmente, se refiere a los resultados esperados y a los costos y mecanismos de los resultados reales. SOMMAIRE Problèmes de coopération technique dans la recherche sur l'éducation: considérations sur un programme de recherches colombien/hollandais Cet article est une évaluation subjective des chercheurs hollandais sur un projet commun. Il présente la chronologie et commente les relations entre les coordinateurs du projet hollandais et colombien, le personnel de recherche, et les donateurs. Pour terminer il analyse les perspectives de rendement des recherches ainsi que le coût et les mécanismes de rendement effectif

Allocation of Foreign Aid in a Segmented International Context

Research on the topic of distribution of foreign aid among recipients is regaining momentum. This is understandable in the light of the knowledge that presently the richest 40 percent of the developing world receives twice as much aid per capita as the poorest 40 percent [UNDP (1994)], while once upon a time foreign aid was sought to accomplish exactly the opposite. The distribution of official development assistance (ODA) is conventionally studied in terms of two models: the ‘recipient needs’ model and the ‘donor interest’ model. In the first, foreign aid flows are seen to satisfy the socio-economic needs of the recipient countries. In the second, national interests of donors, whether these are military, political or commercial, are seen to determine the direction and size of the foreign aid. Empirical studies were made to ascertain and understand whether, on balance, foreign aid is motivated by recipient need or donor interest. There is one class of studies, for example, Mcgillivray (1989), which estimates for donors a compound measure of their allocation bias. The other class of studies, i.e., Maizels and Nissanke (1984) and Grilli and Riess (1992), employs regression analysis to explain allocation of foreign aid by representative variables of recipient need and donor interest

An Update on the 0Z Project

We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we have found from ~1550 moderate resolution follow up spectra. One of these, HE1424-0241, has highly anomalous abundance ratios not seen in any previously known halo giant, with very deficient Si, moderately deficient Ca and Ti, highly enhanced Mn and Co, and low C, all with respect to Fe. We suggest a SNII where the nucleosynthetic yield for explosive alpha-burning nuclei was very low compared to that for the hydrostatic alpha-burning element Mg, which is normal in this star relative to Fe. A second, less extreme, outlier star with high [Sc/Fe] has also been found. We examine the extremely metal-poor tail of the HES metallicity distribution function (MDF). We suggest on the basis of comparison of our high resolution detailed abundance analyses with [Fe/H](HES) for stars in our sample that the MDF inferred from follow up spectra of the HES sample of candidate EMP stars is heavily contaminated for [Fe/H](HES) < -3 dex; many of the supposed EMP stars below that metallicity are of substantially higher Fe-metallicity, including most of the very C-rich stars, or are spurious objects.Comment: to appear in conference proceedings "First Stars III", ed. B. O'Shea, A. Heger & T.Abel, 4 pages, 2 figure

Direct observation of quantum phonon fluctuations in a one dimensional Bose gas

We report the first direct observation of collective quantum fluctuations in a continuous field. Shot-to-shot atom number fluctuations in small sub-volumes of a weakly interacting ultracold atomic 1D cloud are studied using \textit{in situ} absorption imaging and statistical analysis of the density profiles. In the cloud centers, well in the \textit{quantum quasicondensate} regime, the ratio of chemical potential to thermal energy is $\mu/ k_B T\simeq4$, and, owing to high resolution, up to 20% of the microscopically observed fluctuations are quantum phonons. Within a non-local analysis at variable observation length, we observe a clear deviation from a classical field prediction, which reveals the emergence of dominant quantum fluctuations at short length scales, as the thermodynamic limit breaks down.Comment: 4 pages, 3 figures (Supplementary material 3 pages, 3 figures

Femtosecond transparency in the extreme ultraviolet

Electromagnetically induced transparency-like behavior in the extreme ultraviolet (XUV) is studied theoretically, including the effect of intense 800 nm laser dressing of He 2s2p (1Po) and 2p^2 (1Se) autoionizing states. We present an ab initio solution of the time-dependent Schrodinger equation (TDSE) in an LS-coupling configuration interaction basis set. The method enables a rigorous treatment of optical field ionization of these coupled autoionizing states into the N = 2 continuum in addition to N = 1. Our calculated transient absorption spectra show encouraging agreement with experiment.Comment: 25 pages, 7 figures, 1 tabl

Studies related to primitive chemistry. A proton and nitrogen-14 nuclear magnetic resonance amino acid and nucleic acid constituents and a and their possible relation to prebiotic

Preliminary proton nuclear magnetic resonance (NMR) studies were made to determine the applicability of this technique for the study of interactions between monomeric and polymeric amino acids with monomeric nucleic acid bases and nucleotides. Proton NMR results for aqueous solutions (D2O) demonstrated interactions between the bases cytosine and adenine and acidic and aromatic amino acids. Solutions of 5'-AMP admixed with amino acids exhibited more complex behavior but stacking between aromatic rings and destacking at high amino acids concentration was evident. The multisite nature of 5'-AMP was pointed out. Chemical shift changes for adenine and 5'-AMP with three water soluble polypeptides demonstrated that significant interactions exist. It was found that the linewidth-pH profile of each amino acid is unique. It is concluded that NMR techniques can give significant and quantitative data on the association of amino acid and nucleic acid constituents