2,859 research outputs found
Formation of superheavy nuclei in cold fusion reactions
Within the concept of the dinuclear system (DNS), a dynamical model is
proposed for describing the formation of superheavy nuclei in complete fusion
reactions by incorporating the coupling of the relative motion to the nucleon
transfer process. The capture of two heavy colliding nuclei, the formation of
the compound nucleus and the de-excitation process are calculated by using an
empirical coupled channel model, solving a master equation numerically and
applying statistical theory, respectively. Evaporation residue excitation
functions in cold fusion reactions are investigated systematically and compared
with available experimental data. Maximal production cross sections of
superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles
are obtained. Isotopic trends in the production of the superheavy elements
Z=110, 112, 114, 116, 118 and 120 are analyzed systematically. Optimal
combinations and the corresponding excitation energies are proposed.Comment: 18 pages, 8 figure
Possible Way to Synthesize Superheavy Element Z=117
Within the framework of the dinuclear system model, the production of
superheavy element Z=117 in possible projectile-target combinations is analyzed
systematically. The calculated results show that the production cross sections
are strongly dependent on the reaction systems. Optimal combinations,
corresponding excitation energies and evaporation channels are proposed in this
letter, such as the isotopes ^{248,249}Bk in ^{48}Ca induced reactions in 3n
evaporation channels and the reactions ^{45}Sc+^{246,248}Cm in 3n and 4n
channels, and the system ^{51}V+^{244}Pu in 3n channel.Comment: 10 pages, 4 figures, 1 tabl
A tunable radiation source by coupling laser-plasma-generated electrons to a periodic structure
Near-infrared radiation around 1000 nm generated from the interaction of a high-density MeV electron beam, obtained by impinging an intense ultrashort laser pulse on a solid target, with a metal grating is observed experimentally. Theoretical modeling and particle-in-cell simulation suggest that the radiation is caused by the Smith-Purcell mechanism. The results here indicate that tunable terahertz radiation with tens GV=m ļ¬eld strength can be achieved by using appropriate grating parameter
Spectra of Free Diquark in the Bethe-Salpeter Approach
In this work, we employ the Bethe-Salpeter (B-S) equation to investigate the
spectra of free diquarks and their B-S wave functions. We find that the B-S
approach can be consistently applied to study the diqaurks with two heavy
quarks or one heavy and one light quarks, but for two light-quark systems, the
results are not reliable. There are a few free parameters in the whole scenario
which can only be fixed phenomenologically. Thus, to determine them, one has to
study baryons which are composed of quarks and diquarks.Comment: 16 pages, no figure
Ganoderma lucidum polysaccharide loaded sodium alginate micro-particles prepared via electrospraying in controlled deposition environments
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Ganoderma lucidum polysaccharide (GLP) is a functional food source deployed in preventative medicine. However, applications utilizing GLP are limited due to oxidative and acidic environmental damage. Advances in preserving GLP structure (and therefore function), in situ, will diversify their applications within biomedical fields (drug and antibacterial active delivery via the enteral route). In this study, GLP loaded sodium alginate (NaAlg) micro-particles (size range 225ā355 Ī¼m) were generated using the electrospray (ES) process. The loading capacity and encapsulation efficiency of GLP for composite particles (collected at different temperatures) were ā¼23% and 71%, respectively. The collection substrate (CaCl2, 1ā20 w/v%) concentration was explored and preliminary findings indicated a 10 w/v% solution to be optimal. The process was further modified by manipulating the collection environment temperature (ā¼25 to 50 Ā°C). Based on this, NaAlg/GLP micro-particles were engineered with variable surface morphologies (porous and crinkled), without effecting the chemical composition of either material (GLP and NaAlg). In-vitro release studies demonstrated pH responsive release rates. Modest release of GLP from micro-particles in simulated gastric fluid (pH ā¼1.7) was observed, while rapid release was exhibited under simulated intestinal conditions (pH ā¼7.4). Release of GLP from NaAlg beads was the greatest from samples prepared at elevated environmental temperatures. These findings demonstrate a facile route to fabricate GLP-NaAlg loaded micro-particles with various shapes, surface topographies and release characteristics via a one-step ES process
High-throughput estimation of crop traits: A review of ground and aerial phenotyping platforms
Crop yields need to be improved in a sustainable manner
to meet the expected worldwide increase in population
over the coming decades as well as the effects of anticipated
climate change. Recently, genomics-assisted breeding has
become a popular approach to food security; in this regard,
the crop breeding community must better link the relationships
between the phenotype and the genotype. While
high-throughput genotyping is feasible at a low cost, highthroughput
crop phenotyping methods and data analytical
capacities need to be improved.
High-throughput phenotyping offers a powerful way to
assess particular phenotypes in large-scale experiments,
using high-tech sensors, advanced robotics, and imageprocessing
systems to monitor and quantify plants in
breeding nurseries and field experiments at multiple scales.
In addition, new bioinformatics platforms are able to embrace
large-scale, multidimensional phenotypic datasets.
Through the combined analysis of phenotyping and genotyping
data, environmental responses and gene functions
can now be dissected at unprecedented resolution. This will aid in finding solutions to currently limited and incremental
improvements in crop yields
Kernel based methods for accelerated failure time model with ultra-high dimensional data
<p>Abstract</p> <p>Background</p> <p>Most genomic data have ultra-high dimensions with more than 10,000 genes (probes). Regularization methods with <it>L</it><sub>1 </sub>and <it>L<sub>p </sub></it>penalty have been extensively studied in survival analysis with high-dimensional genomic data. However, when the sample size <it>n </it>āŖ <it>m </it>(the number of genes), directly identifying a small subset of genes from ultra-high (<it>m </it>> 10, 000) dimensional data is time-consuming and not computationally efficient. In current microarray analysis, what people really do is select a couple of thousands (or hundreds) of genes using univariate analysis or statistical tests, and then apply the LASSO-type penalty to further reduce the number of disease associated genes. This two-step procedure may introduce bias and inaccuracy and lead us to miss biologically important genes.</p> <p>Results</p> <p>The accelerated failure time (AFT) model is a linear regression model and a useful alternative to the Cox model for survival analysis. In this paper, we propose a nonlinear kernel based AFT model and an efficient variable selection method with adaptive kernel ridge regression. Our proposed variable selection method is based on the kernel matrix and dual problem with a much smaller <it>n </it>Ć <it>n </it>matrix. It is very efficient when the number of unknown variables (genes) is much larger than the number of samples. Moreover, the primal variables are explicitly updated and the sparsity in the solution is exploited.</p> <p>Conclusions</p> <p>Our proposed methods can simultaneously identify survival associated prognostic factors and predict survival outcomes with ultra-high dimensional genomic data. We have demonstrated the performance of our methods with both simulation and real data. The proposed method performs superbly with limited computational studies.</p
Nernst effect of the new iron-based superconductor LaOFFeAs
We report the first Nernst effect measurement on the new iron-based
superconductor LaOFFeAs . In the normal state, the
Nernst signal is negative and very small. Below a large positive peak
caused by vortex motion is observed. The flux flowing regime is quite large
compared to conventional type-II superconductors. However, a clear deviation of
the Nernst signal from normal state background and an anomalous depression of
off-diagonal thermoelectric current in the normal state between and 50
K are observed. We propose that this anomaly in the normal state Nernst effect
could correlate with the SDW fluctuations.Comment: 8 pages, 4 figures; Latex file changed, references adde
An experiment of the combined treatment of traditional Lei-huo-jiu therapy with Chinese medicine for the lacrimal gland of Sjƶgrenās syndrome
This experiment chooses nonobese diabetic (NOD) mouse as the animal model of Sjƶgrenās syndrome and investigates the morphologic changes, the expression of inflammatory factors and growth factors of this mouseās lacrimal gland in response to a combined treatment of traditional Lei-huo-jiu therapy alone and in combination with Chinese medicine. The methods were to (1) use a morphological approach to directly observe pathological changes of the lacrimal gland in response to combined treatment and (2) to detect the level of tumor necrosis factor (TNF)-Ī±, interleukin (IL)-1, and nuclear factor kappa B (NF-ĪŗB) in lacrimal gland tissue caused by the combined treatments using a immunohistochemical approach. There is a reduction of the mast cellās degranulation and modulation of the level of cytokines in TNF-Ī±, IL-1, and NF-ĪŗB in the combined therapy group. The combined treatment of traditional Lei-huo-jiu therapy with Chinese medicine can improve the pathological changes of the lacrimal gland tissue of the NOD mouse through modulating the level of TNF-Ī±, IL-1, and NF-ĪŗB which results in improved tear secretion and function of the lacrimal gland
- ā¦