2,734 research outputs found
A chondrule in the Chainpur meteorite
Glass occurrence in chondrules as evidence for formation by rapid cooling of liquid droplets - chondritic meteorite
Is Dark Matter made up of Massive Quark Objects?
We suggest that dark matter is made up of massive quark objects that have
survived from the Big Bang, representing the ground state of ``baryonic''
matter. Hence, there was no overall phase transition of the original quark
matter, but only a split-up into smaller objects. We speculate that normal
hadronic matter comes about through enforced phase transitions when such
objects merge or collide, which also gives rise to the cosmic gamma-ray bursts.Comment: 8 pages Latex, no figures; to be published in the Proceedings of Dark
'98, Heidelberg, July 199
Chasing the Smokestack: Strategic Policymaking With Multiple Instruments
Empirical evidence suggesting that a considerable amount of horizontal strategic interaction exists amongst governments is important in light of recent devolutionary trends of many important public programs. The empirical approach in these studies typically relies on estimating reaction functions in a uni-dimensional policy framework, where a nonzero slope estimate is interpreted as evidence in support of strategic interactions. While this framework is a useful representation within certain contexts, it is potentially too restrictive; for example, in models of resource competition, localities may use multiple instruments in their recruiting pursuits, leading to potential strategic interactions across policy instruments. In this study, we first develop a simple theoretic construct that includes resource competition in a world of three-dimensional policy choice. The model suggests that while a zero-sloped reaction function may exist for any particular policy, this does not necessarily imply the absence of strategic interactions. We examine the implications of the model empirically using US state-level panel data over the period 1977-1994. The results suggest that important cross-policy strategic interactions exist, lending support in favor of the multi-dimensional framework, and indicate that uni-dimensional frameworks may present lower bound estimates of the degree of strategic interaction.
A mobile system for active otpical pollution monitoring
The remote monitoring of atmospheric pollutants can now be performed in several ways. Laser radar techniques have proven their ability to reveal the spatial distribution of different species or particles. Classical optical techniques can also be used, but yield the average concentration over a given path and hence no range resolution. One such technique is Differential Optical Absorption Spectroscopy, DOAS. Such schemes can be used to monitor paths that a preliminary lidar investigation has shown to be of interest. Having previously had access to a mobile lidar system, a new system has been completed. The construction builds on experience from using the other system and it is meant to be more of a mobile optical laboratory than just a lidar system. A complete system description is given along with some preliminary usage. Future uses are contemplated
Gamma-Ray Bursts from Primordial Quark Objects in Space
We investigate the possibility that gamma-ray bursts originate in a
concentric spherical shell with a given average redshift and find that this is
indeed compatible with the data from the third BATSE (3B) catalog. It is also
shown that there is enough freedom in the choice of unknown burst properties to
allow even for extremely large distances to the majority of bursts. Therefore,
we speculate about an early, and very energetic, origin of bursts, and suggest
that they come from phase transitions in massive objects of pure quark matter,
left over from the Big Bang.Comment: 11 pages, Latex, 3 postscript figures, to be publ in the Proc of the
Joint Meeting of the Networks 'The Fundamental Structure of Matter' and
'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 199
Gubernatorial Reputation and Vertical Tax Externalities: All Smoke, No Fire?
This paper investigates whether reputation-building strategies guide U.S. governorsâ responses to changes in federal cigarette taxes (i.e. vertical tax interactions). Using 1975-2000 state cigarette tax data, we find that reputation-building strategies affect the nature of vertical tax externalities. Lame duck governors exhibit a more negative response to changes in the federal cigarette tax. Thus, by reducing the state tax base and by causing a decline in the state tax, an increase in the federal tax rate reduces state tax revenues in states headed by lame ducks
Behavioral profiling of SLC38A10 knockout mice using the multivariate concentric square fieldâą test
Introduction: SLC38A10 is a gene that encodes the SLC38A10 protein, also known as SNAT10. The SLC38 family is evolutionary old, and SLC38A10 is one of the oldest members of the family. It is ubiquitously expressed, and its substrates are glutamine, glutamate, alanine, aspartate, and serine. However, little is known about its biological importance.Methods: In the current study, an SLC38A10 knockout mouse was run in the multivariate concentric square fieldTM (MCSF) test. The MCSF test gives the mouse a choice of areas to explore; sheltered areas, elevated and illuminated areas, or open spaces, and a behavioral profile is obtained. The multivariate data obtained were analyzed (i) for each parameter, (ii) parameters grouped into functional categories, and (iii) with a principal component analysis.Results: In the trend analysis, knockout mice had a decreased exploratory behavior compared to controls but did not show a distinct grouping in the principal component analysis.Discussion: There was not a pronounced difference in the behavioral profile in SLC38A10 knockout mice compared to their wild-type controls, although subtle alterations in zones associated with exploratory behavior and risk assessment in female and male knockout mice, respectively, could be observed. These results imply that a loss of function of the SLC38A10 protein in mice does not drastically alter behavior in the MSCF test
Fast Searching in Packed Strings
Given strings and the (exact) string matching problem is to find all
positions of substrings in matching . The classical Knuth-Morris-Pratt
algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear
time which is optimal if we can only read one character at the time. However,
most strings are stored in a computer in a packed representation with several
characters in a single word, giving us the opportunity to read multiple
characters simultaneously. In this paper we study the worst-case complexity of
string matching on strings given in packed representation. Let be
the lengths and , respectively, and let denote the size of the
alphabet. On a standard unit-cost word-RAM with logarithmic word size we
present an algorithm using time O\left(\frac{n}{\log_\sigma n} + m +
\occ\right). Here \occ is the number of occurrences of in . For this improves the bound of the Knuth-Morris-Pratt algorithm.
Furthermore, if our algorithm is optimal since any
algorithm must spend at least \Omega(\frac{(n+m)\log
\sigma}{\log n} + \occ) = \Omega(\frac{n}{\log_\sigma n} + \occ) time to
read the input and report all occurrences. The result is obtained by a novel
automaton construction based on the Knuth-Morris-Pratt algorithm combined with
a new compact representation of subautomata allowing an optimal
tabulation-based simulation.Comment: To appear in Journal of Discrete Algorithms. Special Issue on CPM
200
Pearson cross-correlation in the first four black hole binary mergers
We adopt the Pearson cross-correlation measure to analyze the LIGO Hanford and LIGO Livingston detector data streams around the events GW150914, GW151012,GW151226 and GW170104. We find that the Pearson cross-correlation method is sensitive to these signals, with correlations peaking when the black hole binaries reconstructed by the LIGO Scientific and Virgo Collaborations, are merging. We compare the obtained cross-correlations with the statistical correlation fluctuations arising in simulated Gaussian noise data and in LIGO data at times when no event is claimed. Our results for the significance of the observed cross-correlations are broadly consistent with those announced by the LIGO Scientific and Virgo Collaborations based on matched-filter analysis. In the same data, if we subtract the maximum likelihood waveforms corresponding to the announced signals, no residual cross-correlations persists at a statistically significant level
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