152 research outputs found
Shiyalia Ramamrita Ranganathan, le bibliothécaire prodigue
Les idées révolutionnaires de S. R. Ranganathan (1892-1972) ont propulsé l’Inde sur la scène mondiale de la science bibliothéconomique dès les années 1930. Des grands principes aux détails pratiques, rien n’a échappé à sa vision encyclopédique d’un métier tourné vers l’usager
The evolution of classification systems: Ontogeny of the UDC
To classify is to put things in meaningful groups, but the criteria for doing
so can be problematic. Study of evolution of classification includes
ontogenetic analysis of change in classification over time. We present an
empirical analysis of the UDC over the entire period of its development. We
demonstrate stability in main classes, with major change driven by 20th century
scientific developments. But we also demonstrate a vast increase in the
complexity of auxiliaries. This study illustrates an alternative to Tennis'
"scheme-versioning" method.Comment: ISKO conference 201
Synthesis and antiproliferative activity of novel homopiperazine derivatives in leukemia cells
A series of novel homopiperazine derivatives were synthesized and characterized using 1H NMR, LC MS, IR and elemental analysis data. These novel molecules were evaluated for their antiproliferative activity against Reh, leukemia cells using trypan blue and MTT assays. All the molecules showed cytotoxicity with IC50 values between 50-100 μM as calculated by trypan blue assay and greater than 100 μM as calculated by MTT assay. Compound 6b with 3,5-dinitro substituents on phenyl ring of the aryl carboxamide moiety attached to homopiperazine ring showed good activity with IC50 value of 41 μM
Simulation of Guided Wave Propagation in Isotropic and Composite Structures using LISA
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97117/1/AIAA2012-1387.pd
Can the Zee Model Explain the Observed Neutrino Data?
The eigenvalues and mixing angles in the Zee model are investigated
parameter-independently. When we require |\Delta m^2_{12}/\Delta m^2_{23}| \ll
1 in order to understand the solar and atmospheric data simultaneously, the
only solution is one which gives bi-maximal mixing. It is pointed out that the
observed values \sin^2 2\theta_{solar} \simeq 0.66 in the MSW LMA solution
cannot be explained within the framework of the Zee model, because we derive a
severe constraint on the value of \sin^2 2 \theta_{solar}, \sin^2 2
\theta_{solar} \geq 1 -(1/16)(\Delta m^2_{solar}/\Delta m^2_{atm})^2.Comment: Latex file, 10 pages, 1 figure, explanations and references added,
typos corrected, to be published in Phys.Rev.
Solar Neutrinos with Three Flavor Mixings
The recent 71Ga solar neutrino observation is combined with the 37Cl and
Kamiokande-II observations in an analysis for neutrino masses and mixings. The
allowed parameter region is found for matter enhanced mixings among all three
neutrino flavors. Distortions of the solar neutrino spectrum unique to three
flavors are possible and may be observed in continuing and next generation
experiments.Comment: August 1992 (Revised) PURD-TH-92-
Solar Neutrinos: What We Have Learned
The four operating solar neutrino experiments confirm the hypothesis that the
energy source for solar luminosity is hydrogen fusion. However, the measured
rate for each of the four solar neutrino experiments differs significantly (by
factors of 2.0 to 3.5) from the corresponding theoretical prediction that is
based upon the standard solar model and the simplest version of the standard
electroweak theory. If standard electroweak theory is correct, the energy
spectrum for \b8 neutrinos created in the solar interior must be the same (to
one part in ) as the known laboratory \b8 neutrino energy spectrum.
Direct comparison of the chlorine and the Kamiokande experiments, both
sensitive to \b8 neutrinos, suggests that the discrepancy between theory and
observations depends upon neutrino energy, in conflict with standard
expectations. Monte Carlo studies with 1000 implementations of the standard
solar model confirm that the chlorine and the Kamiokande experiments cannot be
reconciled unless new weak interaction physics changes the shape of the \b8
neutrino energy spectrum. The results of the two gallium solar neutrino
experiments strengthen the conclusion that new physics is required and help
determine a relatively small allowed region for the MSW neutrino parameters.Comment: LaTeX file, 19 pages. For hardcopy with figures contact
[email protected]. Institute for Advanced Study number AST 93/6
Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies
We determine the relative rates of short GRBs in cluster and field early-type
galaxies as a function of the age probability distribution of their
progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the
difference in the growth of stellar mass in clusters and in the field, which
arises from the combined effects of the galaxy stellar mass function, the
early-type fraction, and the dependence of star formation history on mass and
environment. This approach complements the use of the early- to late-type host
galaxy ratio, with the added benefit that the star formation histories of
early-type galaxies are simpler than those of late-type galaxies, and any
systematic differences between progenitors in early- and late-type galaxies are
removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n =
-2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2,
corresponding to n ~ 0 - 1. This is similar to the value inferred from the
ratio of short GRBs in early- and late-type hosts, but it differs from the
value of n ~ -1 for NS binaries in the Milky Way. We stress that this general
approach can be easily modified with improved knowledge of the effects of
environment and mass on the build-up of stellar mass, as well as the effect of
globular clusters on the short GRB rate. It can also be used to assess the age
distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio
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