536 research outputs found
Waldschmidt constants for Stanley-Reisner ideals of a class of graphs
In the present note we study Waldschmidt constants of Stanley-Reisner ideals
of a hypergraph and a graph with vertices forming a bipyramid over a planar
n-gon. The case of the hypergraph has been studied by Bocci and Franci. We
reprove their main result. The case of the graph is new. Interestingly, both
cases provide series of ideals with Waldschmidt constants descending to 1. It
would be interesting to known if there are bounded ascending sequences of
Waldschmidt constants.Comment: 7 pages, 2 figure
Genetics of Euglossini bees (Hymenoptera) in fragments of the Atlantic Forest in the region of Viçosa, MG
With uncontrolled deforestation, forest fragments remain, which in most cases are in different stages of regeneration and present isolated populations. In the present study we analyzed the genetic patterns of Eulaema nigrita populations in seven Atlantic Forest fragments of different sizes and successional stages in the region of Viçosa, MG. This was done by RAPD molecular markers. We observed that the area of the fragments had no effect on the genetic variability of E. nigrita in the direction predicted by meta-population models. Medium-sized well-preserved woods presented the lowest variability, whereas large and small woods were statistically identical. The evidence supports the notion that rural areas present greater dispersal among fragments, implying greater similarity between the populations of fragments located in rural areas when compared to fragments in urban areas.Com o desmatamento descontrolado das florestas há a formação de fragmentos de mata que, na maioria das vezes, se encontram em distintos estágios de regeneração, mantendo populações isoladas. Neste trabalho foi feita a análise dos padrões genéticos de populações de Eulaema nigrita de fragmentos de mata Atlântica de diferentes tamanhos e estágios sucessionais por meio de marcadores moleculares RAPD da região de Viçosa, MG. Pode-se verificar que a área dos fragmentos não apresentou efeito sobre a variabilidade genética em E. nigrita na direção predita pelos modelos de metapopulação. Uma mata de tamanho médio e bem preservada apresentou a menor variabilidade, enquanto matas grandes e pequenas foram estatisticamente iguais. As evidências sustentam que áreas rurais apresentam maior dispersão entre fragmentos, implicando maior similaridade entre as populações de fragmentos localizados em áreas rurais se comparados com fragmentos nas áreas urbanizadas
Design and Manufacture of a Prototype for a Spiral Magnetic Array Filter
• Fleenor Manufacturing has a patent-pending spiral filter that uses a patented magnetic array to remove magnetic particles from hydraulic fluid
• Fleenor needs experimental data to prove the effectiveness of the filter in controlled condition
Elliptic Thermal Correlation Functions and Modular Forms in a Globally Conformal Invariant QFT
Global conformal invariance (GCI) of quantum field theory (QFT) in two and
higher space-time dimensions implies the Huygens' principle, and hence,
rationality of correlation functions of observable fields (see Commun. Math.
Phys. 218 (2001) 417-436; hep-th/0009004). The conformal Hamiltonian has
discrete spectrum assumed here to be finitely degenerate. We then prove that
thermal expectation values of field products on compactified Minkowski space
can be represented as finite linear combinations of basic (doubly periodic)
elliptic functions in the conformal time variables (of periods 1 and )
whose coefficients are, in general, formal power series in
involving spherical functions of the "space-like"
fields' arguments. As a corollary, if the resulting expansions converge to
meromorphic functions, then the finite temperature correlation functions are
elliptic. Thermal 2-point functions of free fields are computed and shown to
display these features. We also study modular transformation properties of
Gibbs energy mean values with respect to the (complex) inverse temperature
(). The results are used to obtain the
thermodynamic limit of thermal energy densities and correlation functions.Comment: LaTex. 56 pages. The concept of global conformal invariance set in a
historical perspective (new Sect. 1.1 in the Introduction), references added;
minor corrections in the rest of the pape
RF Design of Normal Conducting Deflecting Structures for the Advanced Photon Source
Use of normal conducting deflecting structures for production of short x-ray pulses is now under consideration at Argonne's Advanced Photon Source (APS). The structures have to produce up to 4 MV maximum deflection per pair of structures with a 1 kHz repetition rate. At the same time, the structures should not cause deterioration of beam properties in the APS ring. Following these requirements, we proposed 2815 MHz standing wave deflecting structures with heavy wakefield damping. In this paper we discuss design considerations and present our current design
A Novel Target-Height Estimation Approach Using Radar-Wave Multipath Propagation for Automotive Applications
This paper introduces a novel target height estimation approach
using a Frequency Modulation Continuous Wave (FMCW) automotive radar. The
presented algorithm takes advantage of radar wave multipath propagation to
measure the height of objects in the vehicle surroundings. A multipath
propagation model is presented first, then a target height is formulated
using geometry, based on the presented propagation model. It is then shown
from Sensor-Target geometry that height estimation of targets is highly
dependent on the radar range resolution, target range and target height. The
high resolution algorithm RELAX is discussed and applied to collected raw
data to enhance the radar range resolution capability. This enables a more
accurate height estimation especially for low targets. Finally, the results
of a measurement campaign using corner reflectors at different heights are
discussed to show that target heights can be very accurately resolved by the
proposed algorithm and that for low targets an average mean height estimation
error of 0.03 m has been achieved by the proposed height finding algorithm
Integrals Over Polytopes, Multiple Zeta Values and Polylogarithms, and Euler's Constant
Let be the triangle with vertices (1,0), (0,1), (1,1). We study certain
integrals over , one of which was computed by Euler. We give expressions for
them both as a linear combination of multiple zeta values, and as a polynomial
in single zeta values. We obtain asymptotic expansions of the integrals, and of
sums of certain multiple zeta values with constant weight. We also give related
expressions for Euler's constant. In the final section, we evaluate more
general integrals -- one is a Chen (Drinfeld-Kontsevich) iterated integral --
over some polytopes that are higher-dimensional analogs of . This leads to a
relation between certain multiple polylogarithm values and multiple zeta
values.Comment: 19 pages, to appear in Mat Zametki. Ver 2.: Added Remark 3 on a Chen
(Drinfeld-Kontsevich) iterated integral; simplified Proposition 2; gave
reference for (19); corrected [16]; fixed typ
Variation and genetic structure of Melipona quadrifasciata Lepeletier (Hymenoptera, Apidae) populations based on ISSR pattern
For a study of diversity and genetic structuring in Melipona quadrifasciata, 61 colonies were collected in eight locations in the state of Minas Gerais, Brazil. By means of PCR analysis, 119 ISSR bands were obtained, 80 (68%) being polymorphic. He and H B were 0.20 and 0.16, respectively. Two large groups were obtained by the UPGMA method, one formed by individuals from Januária, Urucuia, Rio Vermelho and Caeté and the other by individuals from São João Del Rei, Barbacena, Ressaquinha and Cristiano Otoni. The Φst and θB values were 0.65 and 0.58, respectively, thereby indicating high population structuring. UPGMA grouping did not reveal genetic structuring of M. quadrifasciata in function of the tergite stripe pattern. The significant correlation between dissimilarity values and geographic distances (r = 0.3998; p < 0.05) implies possible geographic isolation. The genetic differentiation in population grouping was probably the result of an interruption in gene flow, brought about by geographic barriers between mutually close geographical locations. Our results also demonstrate the potential of ISSR markers in the study of Melipona quadrifasciata population structuring, possibly applicable to the studies of other bee species
Genetic analysis of Melipona quadrifasciata Lep. (Hymenoptera: Apidae, Meliponinae) with RAPD markers
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