272 research outputs found
Fundamental and clinical evaluation of "SCC RIABEAD" kit for immuno radiometric assay of squamous cell carcinoma related antigen.
Classic vector control strategies target mosquitoes indoors as the main transmitters of malaria are indoor-biting and –resting mosquitoes. However, the intensive use of insecticide-treated bed-nets (ITNs) and indoor residual spraying have put selective pressure on mosquitoes to adapt in order to obtain human blood meals. Thus, early-evening and outdoor vector activity is becoming an increasing concern. This study assessed the effect of a deltamethrin-treated net (100 mg/m2) attached to a one-meter high fence around outdoor cattle enclosures on the number of mosquitoes landing on humans. Mosquitoes were collected from four cattle enclosures: Pen A – with cattle and no net; B – with cattle and protected by an untreated net; C – with cattle and protected by a deltamethrin-treated net; D – no cattle and no net. A total of 3217 culicines and 1017 anophelines were collected, of which 388 were Anopheles gambiae and 629 An. ziemanni. In the absence of cattle nearly 3 times more An. gambiae (p<0.0001) landed on humans. The deltamethrin-treated net significantly reduced (nearly three-fold, p<0.0001) culicine landings inside enclosures. The sporozoite rate of the zoophilic An. ziemanni, known to be a secondary malaria vector, was as high as that of the most competent vector An. gambiae; raising the potential of zoophilic species as secondary malaria vectors. After deployment of the ITNs a deltamethrin persistence of 9 months was observed despite exposure to African weather conditions. The outdoor use of ITNs resulted in a significant reduction of host-seeking culicines inside enclosures. Further studies investigating the effectiveness and spatial repellence of ITNs around other outdoor sites, such as bars and cooking areas, as well as their direct effect on vector-borne disease transmission are needed to evaluate its potential as an appropriate outdoor vector control tool for rural Africa
Vortex core transitions in superfluid 3He in globally anisotropic aerogels
Core structures of a single vortex in A-like and B-like phases of superfluid
3He in uniaxially compressed and stretched aerogels are studied by numerically
solving Ginzburg-Landau equations derived microscopically. It is found that,
although any uniaxial deformation leads to a wider A-like phase with the axial
pairing in the pressure-temperature phase diagram, the vortex core states in
the two phases in aerogel depend highly on the type of deformation. In a
compressed aerogel, the first-order vortex core transition (VCT) previously
seen in the bulk B phase appears at any pressure in the B-like phase while no
strange vortex core is expected in the corresponding A-like phase. By contrast,
in a stretched aerogel, the VCT in the B-like phase is lost while another VCT
is expected to occur between a nonunitary core and a polar one in the A-like
phase. Experimental search for these results is hoped to understand correlation
between superfluid 3He and aerogel structure.Comment: 7 pages, 6 figures Text was changed. Resubmitted versio
Soliton-like Spin State in the A-like Phase of 3He in Anisotropic Aerogel
We have found a new stable spin state in the A-like phase of superfluid 3He
confined to intrinsically anisotropic aerogel. The state can be formed by
radiofrequency excitation applied while cooling through the superfluid
transition temperature and its NMR properties are different from the standard
A-like phase obtained in the limit of very small excitation. It is possible
that this new state is formed by textural domain walls pinned by aerogel.Comment: 9 pages, 3 figures. Submitted to J. of Low Tem. Phys. (QFS2007
Proceedings
NMR in Superfluid A-like Phase of He Confined in Globally Deformed Aerogel in Tilted Magnetic Field
NMR spectra in superfluid A-like phases confined in axially deformed aerogel
in presence of a magnetic field inclined with respect to deformation axis is
considered. The characteristic features of dipole frequency shift in axially
compressed and axially stretched cases are compared. In particular, it is shown
that in axially stretched aerogel environment the stability region of
coherently spin precessing mode is rather narrow due to the U(1)LIM effect.Comment: 8 pages, 2 figure
Phase diagram of superfluid 3He in "nematically ordered" aerogel
Results of experiments with liquid 3He immersed in a new type of aerogel are
described. This aerogel consists of Al2O3 strands which are nearly parallel to
each other, so we call it as a "nematically ordered" aerogel. At all used
pressures a superfluid transition was observed and a superfluid phase diagram
was measured. Possible structures of the observed superfluid phases are
discussed.Comment: 6 pages, 8 figures. Submitted to Pis'ma v ZhETF (JETP Letters
Assessing the Forms and Functions of Aggression Using Self-Report: Factor Structure and Invariance of the Peer Conflict Scale in Youths
This study examined the structure of a self-report measure of the forms and functions of aggression in 855 adolescents (582 boys, 266 girls) aged 12 to 19 years recruited from high school, detained, and residential settings. The Peer Conflict Scale (PCS) is a 40-item measure that was developed to improve upon existing measures and provide an efficient, reliable, and valid assessment of four dimensions of aggression (i.e., reactive overt, reactive relational, proactive overt, and proactive relational) in youths. Confirmatory factor analyses showed that a 4-factor model represented a satisfactory solution for the data. The factor structure fit well for both boys and girls and across high school, detained, and residential samples. Internal consistency estimates were good for the 4 factors, and they showed expected associations with externalizing variables (i.e., arrest history, callous-unemotional traits, and delinquency). Reactive and proactive subtypes showed unique associations consistent with previous literature. Implications for the use of the PCS to assess aggression and inform intervention decisions in diverse samples of youths are discussed
Orbital glass and spin glass states of 3He-A in aerogel
Glass states of superfluid A-like phase of 3He in aerogel induced by random
orientations of aerogel strands are investigated theoretically and
experimentally. In anisotropic aerogel with stretching deformation two glass
phases are observed. Both phases represent the anisotropic glass of the orbital
ferromagnetic vector l -- the orbital glass (OG). The phases differ by the spin
structure: the spin nematic vector d can be either in the ordered spin nematic
(SN) state or in the disordered spin-glass (SG) state. The first phase (OG-SN)
is formed under conventional cooling from normal 3He. The second phase (OG-SG)
is metastable, being obtained by cooling through the superfluid transition
temperature, when large enough resonant continuous radio-frequency excitation
are applied. NMR signature of different phases allows us to measure the
parameter of the global anisotropy of the orbital glass induced by deformation.Comment: 7 pages, 6 figures, Submitted to Pis'ma v ZhETF (JETP Letters
Pseudo-single crystal electrochemistry on polycrystalline electrodes : visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction
The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale
Distillation of hydrogen isotopes for polarized HD target
We have developed a cryogenic distillation system to purify
Hydrogen-Deuteride (HD) gas for a polarized HD target in LEPS experiments at
SPring-8. A small amount of ortho-H (0.01%) in the HD gas plays an
important role in efficiently polarizing the HD target. Since there are
15% impurities of H and D in commercially available HD gases, it
is inevitable that the HD gas is purified up to 99.99%. The distillation
system has a cryogenic pot (1721 K) containing many small stainless steel
cells called Heli-pack. Commercial HD gas with an amount of 5.2 mol is fed into
the pot. We carried out three distillation runs by changing temperatures (17.5
K and 20.5 K) and gas extraction speeds (1.3 ml/min and 5.2 ml/min). The
extracted gas was analyzed by using a gas analyzer system combining a
quadrupole mass spectrometer with a gas chromatograph. The HD gas of 1 mol with
a purity better than 99.99% has been successfully obtained. The effective NTS
(Number of Theoretical Stages), which is an indicator of the distillator
performances, is obtained as 37.20.6. This value is in reasonable
agreement with a designed value of 37.9. The HD target is expected to be
efficiently polarized under a well-controlled condition by doping an optimal
amount of ortho-H to the purified HD gas.Comment: 7 pages, 8 figures, 2 tables, updated 2011-12-1
Energy spectra of fractional quantum Hall systems in the presence of a valence hole
The energy spectrum of a two-dimensional electron gas (2DEG) in the
fractional quantum Hall regime interacting with an optically injected valence
band hole is studied as a function of the filling factor and the
separation between the electron and hole layers. The response of the 2DEG
to the hole changes abruptly at of the order of the magnetic length
. At , the hole binds electrons to form neutral () or
charged () excitons, and the photoluminescence (PL) spectrum probes the
lifetimes and binding energies of these states rather than the original
correlations of the 2DEG. The ``dressed exciton'' picture (in which the
interaction between an exciton and the 2DEG was proposed to merely enhance the
exciton mass) is questioned. Instead, the low energy states are explained in
terms of Laughlin correlations between the constituent fermions (electrons and
's) and the formation of two-component incompressible fluid states in the
electron--hole plasma. At , the hole binds up to two Laughlin
quasielectrons (QE) of the 2DEG to form fractionally charged excitons
QE. The previously found ``anyon exciton'' QE is shown to be
unstable at any value of . The critical dependence of the stability of
different QE complexes on the presence of QE's in the 2DEG leads to the
observed discontinuity of the PL spectrum at or .Comment: 16 pages, 14 figures, submitted to PR
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