1,144 research outputs found
Identification of rice chromosome segment substitution line Z322-1-10 and mapping QTLs for agronomic traits from the F<sub>3</sub> population
Chromosome segment substitution lines (CSSLs) are powerful tools to combine naturally occurring genetic variants with favorable alleles in the same genetic backgrounds of elite cultivars. An elite CSSL Z322-1-10 was identified from advanced backcrosses between a japonica cultivar Nipponbare and an elite indica restorer Xihui 18 by SSR marker-assisted selection (MAS). The Z322-1-10 line carries five substitution segments distributed on chromosomes 1, 2, 5, 6 and 10 with an average length of 4.80 Mb. Spikilets per panicle, 1000-grain weight, grain length in the Z322-1-10 line are significantly higher than those in Nipponbare. Quantitative trait loci (QTLs) were identified and mapped for nine agronomic traits in an F3 population derived from the cross between Nipponbare and Z322-1-10 using the restricted maximum likelihood (REML) method in the HPMIXED procedure of SAS. We detected 13 QTLs whose effect ranging from 2.45% to 44.17% in terms of phenotypic variance explained. Of the 13 loci detected, three are major QTL (qGL1, qGW5-1 and qRLW5-1) and they explain 34.68%, 44.17% and 33.05% of the phenotypic variance. The qGL1 locus controls grain length with a typical Mendelian dominance inheritance of 3:1 ratio for long grain to short grain. The already cloned QTL qGW5-1 is linked with a minor QTL for grain width qGW5-2 (13.01%) in the same substitution segment. Similarly, the previously reported qRLW5-1 is also linked with a minor QTL qRLW5-2. Not only the study is important for fine mapping and cloning of the gene qGL1, but also has a great potential for molecular breeding
Study of Loschmidt Echo for a qubit coupled to an XY-spin chain environment
We study the temporal evolution of a central spin-1/2 (qubit) coupled to the
environment which is chosen to be a spin-1/2 transverse XY spin chain. We
explore the entire phase diagram of the spin-Hamiltonian and investigate the
behavior of Loschmidt echo(LE) close to critical and multicritical point(MCP).
To achieve this, the qubit is coupled to the spin chain through the anisotropy
term as well as one of the interaction terms. Our study reveals that the echo
has a faster decay with the system size (in the short time limit) close to a
MCP and also the scaling obeyed by the quasiperiod of the collapse and revival
of the LE is different in comparison to that close to a QCP. We also show that
even when approached along the gapless critical line, the scaling of the LE is
determined by the MCP where the energy gap shows a faster decay with the system
size. This claim is verified by studying the short-time and also the collapse
and revival behavior of the LE at a quasicritical point on the ferromagnetic
side of the MCP. We also connect our observation to the decoherence of the
central spin.Comment: Accepted for publication in EPJ
Charm multiplicity and the branching ratios of inclusive charmless b quark decays in the general two-Higgs-doublet models
In the framework of general two-Higgs-doublet models, we calculate the
branching ratios of various inclusive charmless b decays by using the low
energy effective Hamiltonian including next-to-leading order QCD corrections,
and examine the current status and the new physics effects on the determination
of the charm multiplicity and semileptonic branching ratio .
Within the considered parameter space, the enhancement to the ratio due to the charged-Higgs penguins can be as large as a factor of 8 (3) in
the model III (II), while the ratio can be increased from
the standard model prediction of 2.49% to 4.91% (2.99%) in the model III (II).
Consequently, the value of and can be decreased simultaneously
in the model III. The central value of will be lowered slightly by
about 0.003, but the ratio can be reduced significantly from the
theoretical prediction of in the SM to , for GeV, respectively. We find that
the predicted and the measured now agree within roughly one
standard deviation after taking into account the effects of gluonic charged
Higgs penguins in the model III with a relatively light charged Higgs boson.Comment: 25 pages, Latex file, axodraw.sty, 6 figures. Final version to be
published in Phys.Rev.
Goos-H\"{a}nchen-like shifts for Dirac fermions in monolayer graphene barrier
We investigate the Goos-H\"{a}nchen-like shifts for Dirac fermions in
transmission through a monolayer graphene barrier. The lateral shifts, as the
functions of the barrier's width and the incidence angle, can be negative and
positive in Klein tunneling and classical motion, respectively. Due to their
relations to the transmission gap, the lateral shifts can be enhanced by the
transmission resonances when the incidence angle is less than the critical
angle for total reflection, while their magnitudes become only the order of
Fermi wavelength when the incidence angle is larger than the critical angle.
These tunable beam shifts can also be modulated by the height of potential
barrier and the induced gap, which gives rise to the applications in
graphene-based devices.Comment: 5 pages, 5 figure
Laser welding of Cu-Al-Be shape memory alloys: Microstructure and mechanical properties
Cu-based shape memory alloys are potential substitutes of NiTi shape memory alloys, owing to their lower production costs and recent increase inmechanical properties arising frombetter control of the microstructure. The development of joining technologies for advancedmaterials is key to expand to the potential applications of any engineering alloy. In thiswork, laserwelding of single crystal-like Cu-Al-Be shapememory alloys was performed. The microstructure and tensile propertieswere evaluated to understand the effect of laserwelding on the microstructural and mechanical features of thewelded joints. Cycling tests performed for awide range of temperatures revealed that the joints possess extraordinary superelastic recovery after joining, with potential applications in damping devices due to the significant amount of energy that can be absorbed during superelastic deformation
Mutations in two global regulators lower individual mortality in Escherichia coli
There has been considerable investigation into the survival of bacterial cells under stress conditions, but little is known about the causes of mortality in the absence of exogenous stress. That there is a basal frequency of cell death in such populations may reflect that it is either impossible to avoid all lethal events, or alternatively, that it is too costly. Here, through a genetic screen in the model organism Escherichia coli, we identify two mutants with lower frequencies of mortality: rssB and fliA. Intriguingly, these two genes both affect the levels of different sigma factors within the cell. The rssB mutant displays enhanced resistance to multiple external stresses, possibly indicating that the cell gains its increased vitality through elevated resistance to spontaneous, endogenous stresses. The loss of fliA does not result in elevated stress resistance; rather, its survival is apparently due to a decreased physical stress linked to the insertion of the flagellum through the membrane and energy saved through the loss of the motor proteins. The identification of these two mutants implies that reducing mortality is not impossible; rather, due to its cost, it is subject to trade-offs with other traits that contribute to the competitive success of the organism
Endoscopic fluorescence-guided surgery for sinonasal cancer using an antibody-dye conjugate
First published:19 December 2019OBJECTIVE: Endoscopic resection of sinonasal squamous cell carcinoma has become the standard of care, but challenges remain in obtaining clear resection margins. The current study evaluated the feasibility of endoscopic fluorescence-guided surgery (FGS) to improve surgical resection in a human sinus surgical model. METHODS: A fluorescence endoscope optimized for near-infrared (NIR) fluorescence detection was evaluated in a phantom study. Various endoscope diameters (4 and 10 mm) and viewing angles (0, 30, and 45 degrees) were evaluated to determine the sensitivity of the system for IRDye800CW detection at various working distances (1-5 cm). Endoscopic FGS was then validated in a three-dimensional human sinus surgical model to which squamous cell tumors derived from mice were inserted. Mice had received intravenous panitumumab-IRDye800CW and upon fluorescence-guided tumor resection, mean fluorescence intensity (MFI) and tumor-to-background ratio (TBR) were calculated in in situ and ex vivo settings. RESULTS: A significantly higher fluorescence intensity was found when using the 10-mm diameter endoscope compared to the 4mm diameter endoscope (P < .001). No significant difference in MFI was found among the viewing angles of the 4-mm diameter endoscope. Using the human sinus model, the highest MFI and TBR were obtained at a 1-cm working distance compared to longer working distances. CONCLUSION: We demonstrate that clinically acceptable TBRs were obtained with several working distances to discriminate tumor tissue from adjacent normal tissue in a human sinus model, and that endoscopic FGS may have great potential in identifying residual tumor tissue regions during surgery. Laryngoscope, 2019.Zachary P. Hart, Naoki Nishio, Giri Krishnan, Guolan Lu, Quan Zho
Chronic tooth pulp inflammation induces persistent expression of phosphorylated ERK (pERK) and phosphorylated p38 (pp38) in trigeminal subnucleus caudalis
Background: Extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase are transiently phosphorylated (activated) in the spinal cord and trigeminal nucleus by acute noxious stimuli. Acute stimulation of dental pulp induces short-lived ERK activation in trigeminal subnucleus caudalis (Vc), and p38 inhibition attenuates short-term sensitization in Vc induced by acute pulpal stimulation. We have developed a model to study central changes following chronic inflammation of dental pulp that induces long-term sensitization. Here, we examine the effects of chronic inflammation and acute stimulation on the expression of phosphorylated ERK (pERK), phosphorylated p38 (pp38) and Fos in Vc. Results: Chronic inflammation alone induced bilateral expression of pERK and pp38 in Vc, but did not induce Fos expression. Stimulation of both non-inflamed and inflamed pulps significantly increased pERK and pp38 bilaterally; expression was greatest in inflamed, stimulated animals, and was similar following 10-min and 60-min stimulation. Stimulation for 60 min, but not 10 min, induced Fos in ipsilateral Vc; Fos expression was significantly greater in inflamed, stimulated animals. pERK was present in both neurons and astrocytes; pp38 was present in neurons and other non-neuronal, non-astrocytic cell types. Conclusions: This study provides the first demonstration that chronic inflammation of tooth pulp induces persistent bilateral activation of ERK and p38 within Vc, and that this activation is further increased by acute stimulation. This altered activity in intracellular signaling is likely to be linked to the sensitization that is seen in our animal model and in patients with pulpitis. Our data indicate that pERK and pp38 are more accurate markers of central change than Fos expression. In our model, localization of pERK and pp38 within specific cell types differs from that seen following acute stimulation. This may indicate specific roles for different cell types in the induction and maintenance of pulpitic and other types of pain
The Left-Right asymmetry of top quarks in associated top-charged Higgs bosons at the LHC as a probe of the tan parameter
Many extensions of the Standard Model involve two Higgs doublet fields to
break the electroweak symmetry, leading to the existence of three neutral and
two charged Higgs particles. In particular, this is the case of the Minimal
Supersymmetric extension of the Standard Model, the MSSM. A very important
parameter is defined as the ratio of the vacuum expectation value
of the two Higgs doublets. In this paper we focus on the left-right asymmetry
in the production of polarised top quarks in association with charged Higgs
bosons at the LHC. This quantity allows for a theoretically clean determination
of . In the MSSM, the asymmetry remains sensitive to the strong and
electroweak radiative corrections and, thus, to the superparticle spectrum.
Some possible implications of these results are discussed
Control of a novel chaotic fractional order system using a state feedback technique
We consider a new fractional order chaotic system displaying an interesting behavior. A necessary condition for the system to remain chaotic is derived. It is found that chaos exists in the system with order less than three. Using the Routh-Hurwitz and the Matignon stability criteria, we analyze the novel chaotic fractional order system and propose a control methodology that is better than the nonlinear counterparts available in the literature, in the sense of simplicity of implementation and analysis. A scalar control input that excites only one of the states is proposed, and sufficient conditions for the controller gain to stabilize the unstable equilibrium points derived. Numerical simulations confirm the theoretical analysis. © 2013 Elsevier Ltd. All rights reserved
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