155 research outputs found
Araneae and Opiliones From \u3ci\u3eTypha\u3c/i\u3e Spp. And \u3ci\u3ePhragmites Australis\u3c/i\u3e Stands of Green Bay, Lake Michigan, and an Exotic Spider Species Newly Reported From the U.S. Great Lakes Region
Invertebrates were sampled using pan traps in three paired sets of Typha spp. (cattail) and Phragmites australis (giant reed grass) habitats in Lake Michigan’s Green Bay in June and September 2002. The collection included 34 harvestmen belonging to one species (found at all three sites), and 180 spiders belonging to 25 species in eight families. The two habitats yielded similar numbers of spider taxa, and 16 species were restricted to one of the two habitats. Between 10 and 15 species were found at each site, and only five spider species were collected at all three sites.
Four species appear to be new records for the state of Wisconsin, including the linyphiid spiders Hypomma marxii (Keyserling) and Sitalcus ruralis Bishop & Crosby, and the salticid Synageles noxiosus (Hentz). Of particular interest is the first report from the U.S. Great Lakes region of the clubionid spider Clubiona pallidula (Clerck), a species introduced from Eurasia
Density-Dependent Effects on Microhabitat Selection and Activity of Two Species of Larval Ambystoma Salamanders
To be able to distinguish unnatural amphibian declines from natural population fluctuations we need a better understanding of the mechanisms that affect amphibian community structure. Larval pond-breeding salamanders exhibit density-dependent effects on population parameters, but little is known of the effect of density on behaviors that mediate interactions. Two species, Amby1toma tigrinum (tiger salamander) and A. laterale (blue-spotted salamander), were evaluated in laboratory aquaria for intraspecific and interspecific interactions that affect microhabitat selection and activity. Microhabitat selection was studied by partitioning containers into microhabitats that either contained or lacked refuges, and movement was recorded over a hexagonal grid to determine activity during periods of observation. Both species altered microhabitat preferences and activity levels when they shared tanks with con- or heterospecifics. These density-dependent behavioral changes may indicate that fluctuations in population densities result in behavioral responses that may contribute to coexistence
Bose-Einstein Condensation and Spin Mixtures of Optically Trapped Metastable Helium
We report the realization of a BEC of metastable helium-4 atoms (4He*) in an
all optical potential. Up to 10^5 spin polarized 4He* atoms are condensed in an
optical dipole trap formed from a single, focused, vertically propagating far
off-resonance laser beam. The vertical trap geometry is chosen to best match
the resolution characteristics of a delay-line anode micro-channel plate
detector capable of registering single He* atoms. We also confirm the
instability of certain spin state combinations of 4He* to two-body inelastic
processes, which necessarily affects the scope of future experiments using
optically trapped spin mixtures. In order to better quantify this constraint,
we measure spin state resolved two-body inelastic loss rate coefficients in the
optical trap
Violation of the Cauchy-Schwarz inequality with matter waves
The Cauchy-Schwarz (CS) inequality -- one of the most widely used and
important inequalities in mathematics -- can be formulated as an upper bound to
the strength of correlations between classically fluctuating quantities.
Quantum mechanical correlations can, however, exceed classical bounds.Here we
realize four-wave mixing of atomic matter waves using colliding Bose-Einstein
condensates, and demonstrate the violation of a multimode CS inequality for
atom number correlations in opposite zones of the collision halo. The
correlated atoms have large spatial separations and therefore open new
opportunities for extending fundamental quantum-nonlocality tests to ensembles
of massive particles.Comment: Final published version (with minor changes). 5 pages, 3 figures,
plus Supplementary Materia
Anodic growth of nanoporous tin oxide layers in acidic electrolytes
The aim of this work was to synthesize SnO2 nanostructures with various morphologies by simple anodic oxidation (anodization) of metallic tin in acidic electrolytes. A series of Sn foil anodizations was performed in different electrolytes (oxalic acid, citric acid, tartaric acid) with various concentrations. It was confirmed that anodic oxidation of tin in the oxalic acid results in the formation of nanoporous oxide layers with completely open pores on the surface of the electrode. On the other hand, when citric acid or tartaric acid were used as an electrolyte, porous oxide with a compact layer on the surface was formed during electrolysis
The High-Acceptance Dielectron Spectrometer HADES
HADES is a versatile magnetic spectrometer aimed at studying dielectron
production in pion, proton and heavy-ion induced collisions. Its main features
include a ring imaging gas Cherenkov detector for electron-hadron
discrimination, a tracking system consisting of a set of 6 superconducting
coils producing a toroidal field and drift chambers and a multiplicity and
electron trigger array for additional electron-hadron discrimination and event
characterization. A two-stage trigger system enhances events containing
electrons. The physics program is focused on the investigation of hadron
properties in nuclei and in the hot and dense hadronic matter. The detector
system is characterized by an 85% azimuthal coverage over a polar angle
interval from 18 to 85 degree, a single electron efficiency of 50% and a vector
meson mass resolution of 2.5%. Identification of pions, kaons and protons is
achieved combining time-of-flight and energy loss measurements over a large
momentum range. This paper describes the main features and the performance of
the detector system
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Pulmonary Carcinoid Surface Receptor Modulation Using Histone Deacetylase Inhibitors
Study describes the use of a non-cytotoxic dose of histone deacetylase (HDAC) inhibitors to induce pulmonary carcinoid somatostatin receptor subtype 2 (SSTR2) expression to diagnose pulmonary carcinoids
Mean field effects on the scattered atoms in condensate collisions
We consider the collision of two Bose Einstein condensates at supersonic
velocities and focus on the halo of scattered atoms. This halo is the most
important feature for experiments and is also an excellent testing ground for
various theoretical approaches. In particular we find that the typical reduced
Bogoliubov description, commonly used, is often not accurate in the region of
parameters where experiments are performed. Surprisingly, besides the halo pair
creation terms, one should take into account the evolving mean field of the
remaining condensate and on-condensate pair creation. We present examples where
the difference is clearly seen, and where the reduced description still holds.Comment: 6 pages, 4 figure
HADES experiment: di-lepton spectroscopy in p + p (2.2 GeV) and C+C (1 and 2 A GeV) collisions
The HADES (High Acceptance Di-Electron Spectrometer) is a tool designed for lepton pair (e+e−) spectroscopy in pion, proton and heavy ion induced reactions in the 1–2AGeV energy range. One of the goals of the HADES experiment is to study in-medium modifications of hadron properties like effective masses, decay widths, electromagnetic form factors etc. Such effects can be probed with vector mesons ( ρ,ω,ɸ ) decaying into e+e− channel. The identification of vector mesons by means of a HADES spectrometer is based on invariant mass reconstruction of e+e− pairs. The combined information from all spectrometer sub-detectors is used to reconstruct the di-lepton signal. The recent results from 2.2GeV p + p, 1AGeV and 2AGeV C+C experiments are presented.Diaz Medina, Jose, [email protected]
Study of e+,e− production in elementary and nuclear collisions near the production threshold with HADES
HADES is a second generation experiment designed to study dielectron production in proton, pion, and heavy ion induced reactions at the GSI accelerator facility in Darmstadt. The physics programme of HADES is focused on in-medium properties of the light vector mesons. In this contribution we present status of the HADES experiment, demonstrate its capability to identify rare dielectron signal, show first experimental results obtained from C+C reactions at 2 A GeV and shortly discuss physics programme of up-coming experimental runs. © 2004 Elsevier B.V. All rights reserved. 53 1 49 58 Cited By :1
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