330 research outputs found
Resistivity due to a Domain Wall in Ferromagnetic Metal
The resistivity due to a domain wall in ferromagnetic metallic wire is
calculated based on the linear response theory. The interaction between
conduction electrons and the wall is expressed in terms of a classical gauge
field which is introduced by the local gauge transformation in the electron
spin space. It is shown that the wall contributes to the decoherence of
electrons and that this quantum correction can dominate over the Boltzmann
resisitivity, leading to a decrease of resisitivity by nucleation of a wall.
The conductance fluctuation due to the motion of the wall is also investigated.
The results are compared with recent experiments.Comment: 9 pages, 3 figure
Wave function of the radion in the brane background with a massless scalar field and a self-tuning problem
We consider flat solutions in the brane background with a massless scalar
field appearing in 5D . Since there exist bulk singularities or
arises the divergent 4D Planck mass, we should introduce a compact extra
dimension, the size of which is then fixed by brane tension(s) and a bulk
cosmological constant. Inspecting scalar perturbations around the flat
solutions, we find that the flat solutions are stable vacua from the positive
mass spectrum of radion. We show that the massless radion mode is projected out
by the boundary condition arising in cutting off the extra dimension. Thus, the
fixed extra dimension is not alterable, which is not useful toward a
self-tuning of the cosmological constant.Comment: Latex file of 18 pages including 1 eps figur
Transient electric current through an Aharonov-Bohm ring after switching of a Two-Level-System
Response of the electronic current through an Aharonov-Bohm ring after a
two-level-system is switched on is calculated perturbatively by use of
non-equilibrium Green function. In the ballistic case the amplitude of the
Aharonov-Bohm oscillation is shown to decay to a new equilibrium value due to
scattering into other electronic states. Relaxation of Altshuler-Aronov-Spivak
oscillation in diffusive case due to dephasing effect is also calculated. The
time scale of the relaxation is determined by characteristic relaxation times
of the system and the splitting of two-level-system. Oscillation phases are not
affected. Future experimental studies of current response may give us direct
information on characteristic times of mesoscopic systems
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Validation of Melanoma Immune Profile (MIP), a Prognostic Immune Gene Prediction Score for Stage II–III Melanoma
Purpose: Biomarkers are needed to stratify patients with stage II–III melanoma for clinical trials of adjuvant therapy because, while immunotherapy is protective, it also confers the risk of severe toxicity. We previously defined and validated a 53-immune gene melanoma immune profile (MIP) predictive both of distant metastatic recurrence and of disease-specific survival (DSS). Here, we test MIP on a third independent population.
Experimental Design: A retrospective cohort of 78 patients with stage II–III primary melanoma was analyzed using the NanoString assay to measure expression of 53 target genes, and MIP score was calculated. Statistical analysis correlating MIP with DSS, overall survival, distant metastatic recurrence, and distant metastasis-free interval was performed using ROC curves, Kaplan–Meier curves, and standard univariable and multivariable Cox proportional hazards models.
Results: MIP significantly distinguished patients with distant metastatic recurrence from those without distant metastatic recurrence using ROC curve analysis (AUC = 0.695; P = 0.008). We defined high- and low-risk groups based on the cutoff defined by this ROC curve and find that MIP correlates with both DSS and overall survival by ROC curve analysis (AUC = 0.719; P = 0.004 and AUC = 0.698; P = 0.004, respectively). Univariable Cox regression reveals that a high-risk MIP score correlates with DSS (P = 0.015; HR = 3.2).
Conclusions: MIP identifies patients with low risk of death from melanoma and may constitute a clinical tool to stratify patients with stage II–III melanoma for enrollment in clinical trials
Selenoprotein gene nomenclature
The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates
Signatures of three-nucleon interactions in few-nucleon systems
Recent experimental results in three-body systems have unambiguously shown
that calculations based only on nucleon-nucleon forces fail to accurately
describe many experimental observables and one needs to include effects which
are beyond the realm of the two-body potentials. This conclusion owes its
significance to the fact that experiments and calculations can both be
performed with a high accuracy. In this review, both theoretical and
experimental achievements of the past decade will be underlined. Selected
results will be presented. The discussion on the effects of the three-nucleon
forces is, however, limited to the hadronic sector. It will be shown that
despite the major successes in describing these seemingly simple systems, there
are still clear discrepancies between data and the state-of-the-art
calculations.Comment: accepted for publication in Rep. Prog. Phy
Stable, Time-Dependent, Exact Solutions for Brane Models with a Bulk Scalar Field
We derive two classes of brane-world solutions arising in the presence of a
bulk scalar field. For static field configurations, we adopt a time-dependent,
factorizable metric ansatz that allows for radion stabilization. The solutions
are characterized by a non-trivial warping along the extra dimension, even in
the case of a vanishing bulk cosmological constant, and lead to a variety of
inflationary, time-dependent solutions of the 3D scale factor on the brane. We
also derive the constraints necessary for the stability of these solutions
under time-dependent perturbations of the radion field, and we demonstrate the
existence of phenomenologically interesting, stable solutions with a positive
cosmological constant on the brane.Comment: 24 pages, latex, 4 eps figur
The Incremental Cooperative Design of Preventive Healthcare Networks
This document is the Accepted Manuscript version of the following article: Soheil Davari, 'The incremental cooperative design of preventive healthcare networks', Annals of Operations Research, first published online 27 June 2017. Under embargo. Embargo end date: 27 June 2018. The final publication is available at Springer via http://dx.doi.org/10.1007/s10479-017-2569-1.In the Preventive Healthcare Network Design Problem (PHNDP), one seeks to locate facilities in a way that the uptake of services is maximised given certain constraints such as congestion considerations. We introduce the incremental and cooperative version of the problem, IC-PHNDP for short, in which facilities are added incrementally to the network (one at a time), contributing to the service levels. We first develop a general non-linear model of this problem and then present a method to make it linear. As the problem is of a combinatorial nature, an efficient Variable Neighbourhood Search (VNS) algorithm is proposed to solve it. In order to gain insight into the problem, the computational studies were performed with randomly generated instances of different settings. Results clearly show that VNS performs well in solving IC-PHNDP with errors not more than 1.54%.Peer reviewe
An evolutionary approach to a combined mixed integer programming model of seaside operations as arise in container ports
This paper puts forward an integrated optimisation model that combines three distinct problems, namely berth allocation, quay crane assignment, and quay crane scheduling that arise in container ports. Each one of these problems is difficult to solve in its own right. However, solving them individually leads almost surely to sub-optimal solutions. Hence, it is desirable to solve them in a combined form. The model is of the mixed-integer programming type with the objective being to minimize the tardiness of vessels and reduce the cost of berthing. Experimental results show that relatively small instances of the proposed model can be solved exactly using CPLEX. Large scale instances, however, can only be solved in reasonable times using heuristics. Here, an implementation of the genetic algorithm is considered. The effectiveness of this implementation is tested against CPLEX on small to medium size instances of the combined model. Larger size instances were also solved with the genetic algorithm, showing that this approach is capable of finding the optimal or near optimal solutions in realistic times
Clinical significance of Neutrophil gelatinase-associated lipocalin(NGAL) expression in primary rectal cancer
<p>Abstract</p> <p>Background</p> <p>Emerging evidence has demonstrated that Neutrophil gelatinase-associated lipocalin (NGAL) is up-regulated in multiple malignancies, including oesophagus cancer, and plays a critical role in tumorigenesis and progression. However, till now, little is known about the role of NGAL in human rectal cancer. Its association with clinicopathologic characteristics and expression of MMP-9, one of its target genes, has not been reported systematically in rectal cancer. Therefore, to further determine the potential involvement of NGAL in rectal cancer, we have evaluated the expression level of NGAL mRNA by real time RT-PCR, and further elucidated the correlation of NGAL mRNA expression with clinicopathologic features and MMP-9 in rectal cancer.</p> <p>Methods</p> <p>100 paired samples of rectal cancer and adjacent normal tissues obtained from inpatients undergoing surgical operation were allocated into two groups (cancer group and control group). The mRNA expression of NGAL and MMP-9 was determined by real-time RT-PCR. The association between their expression and clinicopathological characteristics of rectal cancer were analysised.</p> <p>Results</p> <p>Among the 100 rectal cancers, 69 cases of NGAL mRNA up-regulation were observed. NGAL mRNA up-regulation was positively correlated with MMP-9 (<it>r</it><sub>s </sub>= 0.393, <it>p </it>< 0.001). In rectal cancer, NGAL mRNA overexpression was significantly associated with depth of invasion (<it>p </it>= 0.028), lymph node metastasis (<it>p </it>= 0.009), venous involvement (<it>p </it>= 0.023) and advanced pTNM stage (<it>p </it>= 0.011).</p> <p>Conclusion</p> <p>In human rectal cancer, NGAL mRNA expression was elevated. NGAL mRNA up-regulation was correlated significantly with tumor progression and MMP-9 mRNA overexpression in rectal cancer, suggesting a more aggressive phenotype. NGAL could be used for rectal cancer characterization.</p
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