917 research outputs found
Direct Hopf Bifurcation in Parametric Resonance of Hybridized Waves
We study parametric resonance of interacting waves having the same wave
vector and frequency. In addition to the well-known period-doubling instability
we show that under certain conditions the instability is caused by a Hopf
bifurcation leading to quasiperiodic traveling waves. It occurs, for example,
if the group velocities of both waves have different signs and the damping is
weak. The dynamics above the threshold is briefly discussed. Examples
concerning ferromagnetic spin waves and surface waves of ferro fluids are
discussed.Comment: Appears in Phys. Rev. Lett., RevTeX file and three postscript
figures. Packaged using the 'uufiles' utility, 33 k
Is the Shroud of Turin in Relation to the Old Jerusalem Historical Earthquake?
Phillips and Hedges suggested, in the scientific magazine Nature (1989), that
neutron radiation could be liable of a wrong radiocarbon dating, while proton
radiation could be responsible of the Shroud body image formation. On the other
hand, no plausible physical reason has been proposed so far to explain the
radiation source origin, and its effects on the linen fibres. However, some
recent studies, carried out by the first author and his Team at the Laboratory
of Fracture Mechanics of the Politecnico di Torino, found that it is possible
to generate neutron emissions from very brittle rock specimens in compression
through piezonuclear fission reactions. Analogously, neutron flux increments,
in correspondence to seismic activity, should be a result of the same
reactions. A group of Russian scientists measured a neutron flux exceeding the
background level by three orders of magnitude in correspondence to rather
appreciable earthquakes (4th degree in Richter Scale). The authors consider the
possibility that neutron emissions by earthquakes could have induced the image
formation on Shroud linen fibres, trough thermal neutron capture by Nitrogen
nuclei, and provided a wrong radiocarbon dating due to an increment in
C(14,6)content. Let us consider that, although the calculated integral flux of
10^13 neutrons per square centimetre is 10 times greater than the cancer
therapy dose, nevertheless it is100 times smaller than the lethal dose.Comment: 13 pages, 1 figur
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High performance electromagnetic railgun launcher
A railgun operates at high pressure (up to 350 MPa) without structural damage and is readily disassembled for inspection, maintenance and component testing. A rail assembly is pressed into a hoop-wound epoxy fiberglass containment tube and clamped within a steel compression frame. The geometry of the rail assembly permits rail movement without insulator intrusion and achieves bore sealing during rail movement at maximum pressure. The rail assembly also has replaceable insulator inserts which are isolated from rail re-bound shock. Fused quartz insulator inserts provide the best results. A flash tube is provided at the gun muzzle to suppress precursor discharge and commutate precursor current back to the armature. To realize increased velocity without sacrificing in-bore projectile stability, a cut-corner projectile is used having a L/D ratio as small as 0.65 which reduces the mass by about 11%.Board of Regents, University of Texas Syste
Proteins associated with pancreatic cancer survival in patients with resectable pancreatic ductal adenocarcinoma.
Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with a dismal prognosis. However, while most patients die within the first year of diagnosis, very rarely, a few patients can survive for >10 years. Better understanding the molecular characteristics of the pancreatic adenocarcinomas from these very-long-term survivors (VLTS) may provide clues for personalized medicine and improve current pancreatic cancer treatment. To extend our previous investigation, we examined the proteomes of individual pancreas tumor tissues from a group of VLTS patients (survival ≥10 years) and short-term survival patients (STS, survival <14 months). With a given analytical sensitivity, the protein profile of each pancreatic tumor tissue was compared to reveal the proteome alterations that may be associated with pancreatic cancer survival. Pathway analysis of the differential proteins identified suggested that MYC, IGF1R and p53 were the top three upstream regulators for the STS-associated proteins, and VEGFA, APOE and TGFβ-1 were the top three upstream regulators for the VLTS-associated proteins. Immunohistochemistry analysis using an independent cohort of 145 PDAC confirmed that the higher abundance of ribosomal protein S8 (RPS8) and prolargin (PRELP) were correlated with STS and VLTS, respectively. Multivariate Cox analysis indicated that 'High-RPS8 and Low-PRELP' was significantly associated with shorter survival time (HR=2.69, 95% CI 1.46-4.92, P=0.001). In addition, galectin-1, a previously identified protein with its abundance aversely associated with pancreatic cancer survival, was further evaluated for its significance in cancer-associated fibroblasts. Knockdown of galectin-1 in pancreatic cancer-associated fibroblasts dramatically reduced cell migration and invasion. The results from our study suggested that PRELP, LGALS1 and RPS8 might be significant prognostic factors, and RPS8 and LGALS1 could be potential therapeutic targets to improve pancreatic cancer survival if further validated
Band-width control in a perovskite-type 3d^1 correlated metal Ca_{1-x}Sr_xVO_3. I. Evolution of the electronic properties and effective mass
Single crystals of the perovskite-type metallic alloy system
CaSrVO were synthesized in order to investigate metallic
properties near the Mott transition. The substitution of a Ca ion for a
Sr ion reduces the band width due to a buckling of the V-O-V bond
angle from for SrVO to for CaVO. Thus,
the value of can be systematically controlled without changing the number
of electrons making CaSrVO: one of the most ideal systems for
studying band-width effects. The Sommerfeld-Wilson's ratio (), the
Kadowaki-Woods ratio (in the same region as heavy Fermion systems), and a large
term in the electric resistivity, even at 300 K, substantiate a large
electron correlation in this system, though the effective mass, obtained by
thermodynamic and magnetic measurements, shows only a systematic but moderate
increase in going from SrVO to CaVO, in contrast to the critical
enhancement expected from the Brinkmann-Rice picture. It is proposed that the
metallic properties observed in this system near the Mott transition can be
explained by considering the effect of a non-local electron correlation.Comment: 14 pages in a Phys. Rev. B camera-ready format with 10 EPS figures
embedded. LaTeX 2.09 source file using "camera.sty" and "prbplug.sty"
provided by N. Shirakawa. For OzTeX (Macintosh), use "ozfig.sty" instead of
"psfig.sty". "ozfig.sty" can be also obtained by e-mail request to N.
Shirakawa: . Submitted to Phys. Rev.
Hearing before the Congressional Oversight Panel
RE: Treasury Secretary Timothy F. Geithner; S. H RG . 111– 7
Reflecting on loss in Papua New Guinea
This article takes up the conundrum of conducting anthropological fieldwork with people who claim that they have 'lost their culture,' as is the case with Suau people in the Massim region of Papua New Guinea. But rather than claiming culture loss as a process of dispossession, Suau claim it as a consequence of their own attempts to engage with colonial interests. Suau appear to have responded to missionization and their close proximity to the colonial-era capital by jettisoning many of the practices characteristic of Massim societies, now identified as 'kastom.' The rejection of kastom in order to facilitate their relations with Europeans during colonialism, followed by the mourning for kastom after independence, both invite consideration of a kind of reflexivity that requires action based on the presumed perspective of another
The T-type calcium channel isoform Ca v 3.1 is a target for the hypnotic effect of the anaesthetic neurosteroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile
BACKGROUND: The mechanisms underlying the role of T-type calcium channels (T-channels) in thalamocortical excitability and oscillations in vivo during neurosteroid-induced hypnosis are largely unknown.
METHODS: We used patch-clamp electrophysiological recordings from acute brain slices ex vivo, recordings of local field potentials (LFPs) from the central medial thalamic nucleus in vivo, and wild-type (WT) and Ca
RESULTS: Patch-clamp recordings showed that 3β-OH inhibited isolated T-currents but had no effect on phasic or tonic γ-aminobutyric acid A currents. Also in acute brain slices, 3β-OH inhibited the spike firing mode more profoundly in WT than in Ca
CONCLUSIONS: The C
Who I Am: The Meaning of Early Adolescents’ Most Valued Activities and Relationships, and Implications for Self-Concept Research
Self-concept research in early adolescence typically measures young people’s self-perceptions of competence in specific, adult-defined domains. However, studies have rarely explored young people’s own views of valued self-concept factors and their meanings. For two major self domains, the active and the social self, this mixed-methods study identified factors valued most by 526 young people from socioeconomically diverse backgrounds in Ireland (10-12 years), and explored the meanings associated with these in a stratified subsample (n = 99). Findings indicate that self-concept scales for early adolescence omit active and social self factors and meanings valued by young people, raising questions about content validity of scales in these domains. Findings also suggest scales may under-represent girls’ active and social selves; focus too much on some school-based competencies; and, in omitting intrinsically salient self domains and meanings, may focus more on contingent (extrinsic) rather than true (intrinsic) self-esteem
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