2,522 research outputs found
Matrix product states and the quantum max-flow/min-cut conjectures
In this note we discuss the geometry of matrix product states with periodic
boundary conditions and provide three infinite sequences of examples where the
quantum max-flow is strictly less than the quantum min-cut. In the first we fix
the underlying graph to be a 4-cycle and verify a prediction of Hastings that
inequality occurs for infinitely many bond dimensions. In the second we
generalize this result to a 2d-cycle. In the third we show that the 2d-cycle
with periodic boundary conditions gives inequality for all d when all bond
dimensions equal two, namely a gap of at least 2^{d-2} between the quantum
max-flow and the quantum min-cut.Comment: 12 pages, 3 figures - Final version accepted for publication on J.
Math. Phy
The Scottish Health Survey Topic Report: Mental Health and Wellbeing; 2015
This report explores factors associated with mental wellbeing and mental health among adults in Scotland using data from the Scottish Health Survey (SHeS). Analyses are based on survey years 2012 to 2013 and include participants aged 16 years and older
The Rare Decays \piee, \etaee and \etamumu$ in Chiral Perturbation Theory
We calculate the decay rates for \piee, \etaee and \etamumu in chiral
perturbation theory. The linear combination of counterterms necessary to render
these amplitudes finite is fixed by the recently measured branching fraction
for \etamumu. We find \Br(\piee ) = 7\pm 1\times 10^{-8} and \Br(\etaee
)=5\pm 1\times 10^{-9}.Comment: (6 pages, 1 figure available on request, uses harvmac.tex), UCSD/PTH
92-23, CALT-68-180
17-AAG Induces Cytoplasmic α-Synuclein Aggregate Clearance by Induction of Autophagy
The accumulation and aggregation of α-synuclein in nerve cells and glia are characteristic features of a number of neurodegenerative diseases termed synucleinopathies. α-Synuclein is a highly soluble protein which in a nucleation dependent process is capable of self-aggregation. The causes underlying aggregate formation are not yet understood, impairment of the proteolytic degradation systems might be involved.Cl the aggregate clearing effects of 17-AAG were abolished and α-synuclein deposits were enlarged. Analysis of LC3-II immunoreactivity, which is an indicator of autophagosome formation, further revealed that 17-AAG led to the recruitment of LC3-II and to the formation of LC3 positive puncta. This effect was also observed in cultured oligodendrocytes derived from the brains of newborn rats. Inhibition of macroautophagy by 3-methyladenine prevented 17-AAG induced occurrence of LC3 positive puncta as well as the removal of α-synuclein aggregates in OLN-A53T cells.Our data demonstrate for the first time that 17-AAG not only causes the upregulation of heat shock proteins, but also is an effective inducer of the autophagic pathway by which α-synuclein can be removed. Hence geldanamycin derivatives may provide a means to modulate autophagy in neural cells, thereby ameliorating pathogenic aggregate formation and protecting the cells during disease and aging
Novel Schizophrenia Risk Gene TCF4 Influences Verbal Learning and Memory Functioning in Schizophrenia Patients
Background: Recently, a role of the transcription factor 4 (TCF4) gene in schizophrenia has been reported in a large genome-wide association study. It has been hypothesized that TCF4 affects normal brain development and TCF4 has been related to different forms of neurodevelopmental disorders. Schizophrenia patients exhibit strong impairments of verbal declarative memory (VDM) functions. Thus, we hypothesized that the disease-associated C allele of the rs9960767 polymorphism of the TCF4 gene led to impaired VDM functioning in schizophrenia patients. Method: The TCF4 variant was genotyped in 401 schizophrenia patients. VDM functioning was measured using the Rey Auditory Verbal Learning Test (RAVLT). Results: Carriers of the C allele were less impaired in recognition compared to those carrying the AA genotype (13.76 vs. 13.06; p = 0.049). Moreover, a trend toward higher scores in patients with the risk allele was found for delayed recall (10.24 vs. 9.41; p = 0.088). The TCF4 genotype did not influence intelligence or RAVLT immediate recall or total verbal learning. Conclusion: VDM function is influenced by the TCF4 gene in schizophrenia patients. However, the elevated risk for schizophrenia is not conferred by TCF4-mediated VDM impairment. Copyright (C) 2011 S. Karger AG, Base
Performance of high mach number scramjets - Tunnel vs flight
While typically analysed through ground-based impulse facilities, scramjets experience significant heating loads in flight, raising engine wall temperatures and the fuel used to cool them beyond standard laboratory conditions. Hence, the present work numerically compares an access-to-space scramjet's performance at both these conditions. The Mach 12 Rectangular-to-Elliptical Shape-Transitioning scramjet flow path is examined via three-dimensional and chemically reacting Reynolds-averaged Navier-Stokes solutions. Flight operation is modelled through 800 K and 1800 K inlet and combustor walls respectively, while fuel is injected at both inlet- and combustor-based stations at 1000 K stagnation temperature. Room temperature walls and fuel plena model shock tunnel conditions. Mixing and combustion performance indicates that while flight conditions promote rapid mixing, high combustor temperatures inhibit the completion of reaction pathways, with reactant dissociation reducing chemical heat release by 16%. However, the heated walls in flight ensured 28% less energy was absorbed by the walls. While inlet fuel injection promotes robust burning of combustor-injected fuel, premature ignition upon the inlet in flight suggests these injectors should be moved further downstream. Coupled with counteracting differences in heat release and loss to the walls, the optimal engine design for flight may differ considerably from that which gives the best performance in the tunnel
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