270 research outputs found
Phenomenological Scaling of Rapidity Dependence for Anisotropic Flows in 25 MeV/nucleon Ca + Ca by Quantum Molecular Dynamics Model
Anisotropic flows (, , and ) of light fragments up till
the mass number 4 as a function of rapidity have been studied for 25
MeV/nucleon Ca + Ca at large impact parameters by Quantum
Molecular Dynamics model. A phenomenological scaling behavior of rapidity
dependent flow parameters (n = 1, 2, 3 and 4) has been found as a
function of mass number plus a constant term, which may arise from the
interplay of collective and random motions. In addition, keeps
almost independent of rapidity and remains a rough constant of 1/2 for all
light fragments.Comment: 4 pages, 5 figure
Scaling of Anisotropic Flows and Nuclear Equation of State in Intermediate Energy Heavy Ion Collisions
Elliptic flow () and hexadecupole flow () of light clusters have
been studied in details for 25 MeV/nucleon Kr + Sn at large
impact parameters by Quantum Molecular Dynamics model with different potential
parameters. Four parameter sets which include soft or hard equation of state
(EOS) with/without symmetry energy term are used. Both number-of-nucleon ()
scaling of the elliptic flow versus transverse momentum () and the scaling
of versus have been demonstrated for the light clusters
in all above calculation conditions. It was also found that the ratio of
keeps a constant of 1/2 which is independent of for all the
light fragments. By comparisons among different combinations of EOS and
symmetry potential term, the results show that the above scaling behaviors are
solid which do not depend the details of potential, while the strength of flows
is sensitive to EOS and symmetry potential term.Comment: 5 pages, 5 figure
Study on the One-Proton Halo Structure in Al
The Glauber theory has been used to investigate the reaction cross section of
proton-rich nucleus Al. A core plus a proton structure is assumed for
Al. HO-type density distribution is used for the core while the density
distribution for the valence proton is calculated by solving the eigenvalue
problem of Woods-Saxon potential. The transparency function in an analytical
expression is obtained adopting multi-Gaussian expansion for the density
distribution. Coulomb correction and finite-range interaction are introduced.
This modified Glauber model is apt for halo nuclei. A dominate s-wave is
suggested for the last proton in Al from our analysis which is possible
in the RMF calculation.Comment: 4 pages, 4 figure
Fabrication and Properties of Ag-nanoparticles Embedded Amorphous Carbon Nanowire/CNT Heterostructures
Carbon nanotubes were subjected to doping with an energetic Ag ion beam, and the carbon nanotubes on the top of the array were transformed into amorphous carbon nanowires with embedded Ag-nanoparticles. The field emission characteristics of these nanowires were investigated. The minimum turn-on and threshold fields were 0.68 and 1.09 V/μm, respectively, which were lower than those of the as-grown carbon nanotubes. This was probably because Ag-nanoparticles embedded in the carbon nanowires reduced the effective work function from 4.59 to 4.23 eV. Large doping amounts produced serious structural damage at the top of the nanowires and impaired the field emission characteristics
Association of LEP G2548A and LEPR Q223R Polymorphisms with Cancer Susceptibility: Evidence from a Meta-Analysis
__Background:__ Numerous epidemiological studies have examined associations of genetic variations in LEP (G2548A, -2548 nucleotide upstream of the ATG start site) and LEPR (Q223R, nonsynonymous SNP in exon 6) with cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis to comprehensively evaluate such associations.
__Methods:__ We searched published literature from MEDLINE, EMBASE, Web of Science and CBM for eligible publications. We also assessed genotype-based mRNA expression data from HapMap for rs7799039 (G2548A) and rs1137101 (Q223R) in normal cell lines derived from 270 subjects with different ethnicities.
__Results:__ The final analysis included 16 published studies of 6569 cases and 8405 controls for the LEP G2548A and 19 studies of 7504 cases and 9581 controls for the LEPR Q223R. Overall, LEP G2548A was statistically significantly associated with an increased risk of overall cancer (AA vs. GG: OR=1.27, 95% CI=1.05-1.54; recessive model: OR=1.19, 9
Experimental demonstration of high sensitivity refractive index sensing based on magnetic plasmons in a simple metallic deep nanogroove array
A high-performance wide-angle refractive index sensor based on a simple one-dimensional (1D) metallic deep nanogroove array with a high aspect ratio is experimentally fabricated and demonstrated. The 1D deep groove array is featured by the excitation of magnetic plasmon (MP), referring to an effective coupling of incident electromagnetic waves with a strong magnetic response induced inside the deep grooves. Utilizing the MP resonances that are extremely sensitive to the surrounding dielectric medium, we successfully achieve a refractive index sensitivity (RIS) up to ∼1300 nm/RIU, which is higher than that of most experimentally designed plasmonic sensors in the infrared region. Importantly, benefiting from angle-independent MP resonances with strong confinement of the magnetic field inside the deep grooves and strong electric field localization at the groove openings, we demonstrate wide-angle sensing capability valid in a broadband infrared region with an excellent linear dependence on the change of refractive index. Such a MP-based sensor, together with its simple 1D flat nature and ease of fabrication, has great potential for the practical design of high sensitive, cost-effective and compact sensing devices
Responses to precipitation treatment for Haloxylon ammodendron growing on contrasting textured soils
The responses to precipitation of Haloxylon ammodendron (C.A. Mey.) Bunge (Chenopodiaceae), a small xerophilous tree growing on contrasting textured soils, were evaluated under no, natural, and double precipitation treatments during the entire growing season of 2006. The contrasting textured soils are sandy and heavy textured, and both are the original habitat of H. ammodendron at the south edge of Gubantonggute Desert, Central Asia. Photosynthesis, leaf water potential, transpiration, water use efficiency and leaf biomass production were monitored throughout the growing season. Root distribution of H. ammodendron was evaluated at the end of the experiment. Overall, this small tree did not show significant response to a large summer precipitation pulse or precipitation treatments, in terms of photosynthetic carbon assimilation on either soil. The leaf water potential, transpiration, and water use efficiency appeared to be highly sensitive to a large precipitation pulse and precipitation treatments in sandy soil; and leaf biomass production was also much higher for plants in sandy than that of heavy-textured soil. In sandy soil, defoliation occurred when pre-dawn leaf water potential dropped below -3.0 MPa, while in heavy-textured soil, defoliation occurred when pre-dawn leaf water potential dropped below -3.75 MPa. For similar above-ground parts, the small trees at the sandy site developed much deeper root systems and had nearly double the surface area of feeder roots compared to those at the heavy-textured site. Partially owning to the deeper and larger root system, H. ammodendron growing at coarse-textured site was in better water conditions than those at heavy-textured site under the same climatic conditions
Extended Line Emission in the BCG of Abell 2390
We report CFHT/SITELLE imaging Fourier Transform Spectrograph observations of
the Brightest Cluster Galaxy (BCG) of galaxy cluster Abell 2390 at z=0.228. The
BCG displays a prominent cone of emission in H, H, [NII], and
[OII] to the North-West with PA = 42, 4.4 arcsec in length (15.9 kpc),
which is associated with elongated and asymmetric Chandra soft X-ray emission.
The H flux map also contains a "hook" of H and [NII] emission
resulting in a broadened northern edge to the cone. Using SITELLE/LUCI software
we extract emission line flux, velocity, velocity dispersion, and continuum
maps, and utilize them to derive flux ratio maps to determine ionization
mechanisms and dynamical information in the BCG's emission line region. The
Baldwin-Phillips-Terlevich diagnostics on the BCG cone indicate a composite
ionization origin of photoionization due to star formation and shock. Strong
LINER-like emission is seen in the nuclear region which hosts an AGN. As Abell
2390 is a cool-core cluster, we suggest that the cooling flow is falling onto
the central BCG and interacting with the central AGN. The AGN produces jets
that inflate "bubbles" of plasma in the ICM, as is often observed in local
galaxy clusters. Furthermore, combining signs of AGN activities from radio,
optical emission line and X-ray data over a large range of physical scale, we
find evidence for three possible episodes of AGN activity in different epochs
associated with the Abell 2390 BCG.Comment: 15 pages, 13 figures, accepted by MNRA
Genetic Association Study of Common Mitochondrial Variants on Body Fat Mass
Mitochondria play a central role in ATP production and energy metabolism. Previous studies suggest that common variants in mtDNA are associated with several common complex diseases, including obesity. To test the hypothesis that common mtDNA variants influence obesity-related phenotypes, including BMI and body fat mass, we genotyped a total of 445 mtSNPs across the whole mitochondrial genome in a large sample of 2,286 unrelated Caucasian subjects. 72 of these 445 mtSNPs passed quality control criteria, and were used for subsequent analyses. We also classified all subjects into nine common European haplogroups. Association analyses were conducted for both BMI and body fat mass with single mtSNPs and mtDNA haplogroups. Two mtSNPs, mt4823 and mt8873 were detected to be significantly associated with body fat mass, with adjusted P values of 4.94×10-3 and 4.58×10-2, respectively. The minor alleles mt4823 C and mt8873 A were associated with reduced fat mass values and the effect size (β) was estimated to be 3.52 and 3.18, respectively. These two mtSNPs also achieved nominally significant levels for association with BMI. For haplogroup analyses, we found that haplogroup X was strongly associated with both BMI (adjusted P = 8.31×10-3) and body fat mass (adjusted P = 5.67×10-4) Subjects classified as haplogroup X had lower BMI and fat mass values, with the β estimated to be 2.86 and 6.03, respectively. Our findings suggest that common variants in mitochondria might play a role in variations of body fat mass. Further molecular and functional studies will be needed to clarify the potential mechanism
Neurochemical Properties of the Synapses in the Pathways of Orofacial Nociceptive Reflexes
The brainstem premotor neurons of the facial nucleus (VII) and hypoglossal (XII) nucleus can integrate orofacial nociceptive input from the caudal spinal trigeminal nucleus (Vc) and coordinate orofacial nociceptive reflex (ONR) responses. However, the synaptoarchitectures of the ONR pathways are still unknown. In the current study, we examined the distribution of GABAergic premotor neurons in the brainstem local ONR pathways, their connections with the Vc projections joining the brainstem ONR pathways and the neurochemical properties of these connections. Retrograde tracer fluoro-gold (FG) was injected into the VII or XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the Vc. Immunofluorescence histochemical labeling for inhibitory/excitatory neurotransmitters combined with BDA/FG tracing showed that GABAergic premotor neurons were mainly distributed bilaterally in the ponto-medullary reticular formation with an ipsilateral dominance. Some GABAergic premotor neurons made close appositions to the BDA-labeled fibers coming from the Vc, and these appostions were mainly distributed in the parvicellular reticular formation (PCRt), dorsal medullary reticular formation (MdD), and supratrigeminal nucleus (Vsup). We further examined the synaptic relationships between the Vc projecting fibers and premotor neurons in the VII or XII under the confocal laser-scanning microscope and electron microscope, and found that the BDA-labeled axonal terminals that made asymmetric synapses on premotor neurons showed vesicular glutamate transporter 2 (VGluT2) like immunoreactivity. These results indicate that the GABAergic premotor neurons receive excitatory neurotransmission from the Vc and may contribute to modulating the generation of the tonic ONR
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