590 research outputs found
Ultrafast relaxation dynamics of the antiferrodistortive phase in Ca doped SrTiO3
The ultrafast dynamics of the octahedral rotation in Ca:SrTiO3 is studied by
time resolved x-ray diffraction after photo excitation over the band gap. By
monitoring the diffraction intensity of a superlattice reflection that is
directly related to the structural order parameter of the soft-mode driven
antiferrodistortive phase in Ca:SrTiO3, we observe a ultrafast relaxation on a
0.2 ps timescale of the rotation of the oxygen octahedron, which is found to be
independent of the initial temperaure despite large changes in the
corresponding soft-mode frequency. A further, much smaller reduction on a
slower picosecond timescale is attributed to thermal effects. Time-dependent
density-functional-theory calculations show that the fast response can be
ascribed to an ultrafast displacive modification of the soft-mode potential
towards the normal state, induced by holes created in the oxygen 2p states
Haldane, Large-D and Intermediate-D States in an S=2 Quantum Spin Chain with On-Site and XXZ Anisotropies
Using mainly numerical methods, we investigate the ground-state phase diagram
of the S=2 quantum spin chain described by , where
denotes the anisotropy parameter of the nearest-neighbor interactions and
the on-site anisotropy parameter. We restrict ourselves to the case with
and for simplicity. Each of the phase boundary lines
is determined by the level spectroscopy or the phenomenological renormalization
analysis of numerical results of exact-diagonalization calculations. The
resulting phase diagram on the - plane consists of four phases; the
XY 1 phase, the Haldane/large- phase, the intermediate- phase and the
N\'eel phase. The remarkable natures of the phase diagram are: (1) the Haldane
state and the large- state belong to the same phase; (2) there exists the
intermediate- phase which was predicted by Oshikawa in 1992; (3) the shape
of the phase diagram on the - plane is different from that believed
so far. We note that this is the first report of the observation of the
intermediate- phase
Entanglement purification of multi-mode quantum states
An iterative random procedure is considered allowing an entanglement
purification of a class of multi-mode quantum states. In certain cases, a
complete purification may be achieved using only a single signal state
preparation. A physical implementation based on beam splitter arrays and
non-linear elements is suggested. The influence of loss is analyzed in the
example of a purification of entangled N-mode coherent states.Comment: 6 pages, 3 eps-figures, using revtex
A 64k pixel CMOS-DEPFET module for the soft X-rays DSSC imager operating at MHz-frame rates
: The 64k pixel DEPFET module is the key sensitive component of the DEPFET Sensor with Signal Compression (DSSC), a large area 2D hybrid detector for capturing and measuring soft X-rays at the European XFEL. The final 1-megapixel camera has to detect photons with energies between [Formula: see text] and [Formula: see text], and must provide a peak frame rate of [Formula: see text] to cope with the unique bunch structure of the European XFEL. This work summarizes the functionalities and properties of the first modules assembled with full-format CMOS-DEPFET arrays, featuring [Formula: see text] hexagonally-shaped pixels with a side length of 136 μm. The pixel sensors utilize the DEPFET technology to realize an extremely low input capacitance for excellent energy resolution and, at the same time, an intrinsic capability of signal compression without any gain switching. Each pixel of the readout ASIC includes a DEPFET-bias current cancellation circuitry, a trapezoidal-shaping filter, a 9-bit ADC and a 800-word long digital memory. The trimming, calibration and final characterization were performed in a laboratory test-bench at DESY. All detector features are assessed at [Formula: see text]. An outstanding equivalent noise charge of [Formula: see text]e-rms is achieved at 1.1-MHz frame rate and gain of 26.8 Analog-to-Digital Unit per keV ([Formula: see text]). At [Formula: see text] and [Formula: see text], a noise of [Formula: see text] e-rms and a dynamic range of [Formula: see text] are obtained. The highest dynamic range of [Formula: see text] is reached at [Formula: see text] and [Formula: see text]. These values can fulfill the specification of the DSSC project
Rare Copy Number Variants in \u3cem\u3eNRXN1\u3c/em\u3e and \u3cem\u3eCNTN6\u3c/em\u3e Increase Risk for Tourette Syndrome
Tourette syndrome (TS) is a model neuropsychiatric disorder thought to arise from abnormal development and/or maintenance of cortico-striato-thalamo-cortical circuits. TS is highly heritable, but its underlying genetic causes are still elusive, and no genome-wide significant loci have been discovered to date. We analyzed a European ancestry sample of 2,434 TS cases and 4,093 ancestry-matched controls for rare (\u3c 1% frequency) copy-number variants (CNVs) using SNP microarray data. We observed an enrichment of global CNV burden that was prominent for large (\u3e 1 Mb), singleton events (OR = 2.28, 95% CI [1.39–3.79], p = 1.2 × 10−3) and known, pathogenic CNVs (OR = 3.03 [1.85–5.07], p = 1.5 × 10−5). We also identified two individual, genome-wide significant loci, each conferring a substantial increase in TS risk (NRXN1 deletions, OR = 20.3, 95% CI [2.6–156.2]; CNTN6 duplications, OR = 10.1, 95% CI [2.3–45.4]). Approximately 1% of TS cases carry one of these CNVs, indicating that rare structural variation contributes significantly to the genetic architecture of TS
Optimal military spending in the US: A time series analysis
This paper extends previous work on the optimal size of government spending by including nested functional decompositions of military spending into consumption and investment. Post World War II US data are then used to estimate nested non-linear growth models using semi-parametric methods. As expected, investments in military and non-military expenditure are both found to be productive expenditures with respect to the private production. Moreover there is little evidence to suggest that current military spending is having a negative impact on economic growth in the US, while civilian consumption only tends to have only a weak impact. This does not imply that society will necessarily benefit from a reallocation of more spending to the military sector, nor that it is the best way to achieve economic growth. © 2010 Elsevier B.V
Transcriptomic alterations induced by Monuron in rat and human renal proximal tubule cells in vitro and comparison to rat renal-cortex in vivo
Monuron (1,1-dimethyl-3-(4-chlorophenyl)urea) is a non-selective phenylurea herbicide, widely used in developing countries although concerns have been raised about its toxicity and carcinogenicity. Monuron was evaluated by the National Toxicology Program in 1988 and shown to be a male rat-specific renal carcinogen. We report that oral administration of Monuron to male rats for 3 days, leads to a larger number of genes being differentially expressed in the renal-cortex than in the liver. Further, we observed up-regulation of cell cycle genes and genes involved in cell proliferation in the renal-cortex while in the liver xenobiotic metabolising enzymes were up-regulated. We also identified one commonly down-regulated gene in both organs – fragile histidine triad gene (Fhit), a putative tumour suppressor gene; however the down-regulation was only significant at the protein level in the liver. In addition, we conducted in vitro whole-genome transcriptomics studies with human and rat renal cortical cells. Rat cells exposed to Monuron showed down-regulation of sterol biosynthesis, spliceosome and cell cycle genes and up-regulation of genes involved in amino acid metabolism and transport. No genes were found to be differentially expressed in human cells exposed to Monuron. Overall, the findings from the in vitro studies showed very little overlap with the whole animal findings
Improved high-temperature expansion and critical equation of state of three-dimensional Ising-like systems
High-temperature series are computed for a generalized Ising model with
arbitrary potential. Two specific ``improved'' potentials (suppressing leading
scaling corrections) are selected by Monte Carlo computation. Critical
exponents are extracted from high-temperature series specialized to improved
potentials, achieving high accuracy; our best estimates are:
, , , ,
. By the same technique, the coefficients of the small-field
expansion for the effective potential (Helmholtz free energy) are computed.
These results are applied to the construction of parametric representations of
the critical equation of state. A systematic approximation scheme, based on a
global stationarity condition, is introduced (the lowest-order approximation
reproduces the linear parametric model). This scheme is used for an accurate
determination of universal ratios of amplitudes. A comparison with other
theoretical and experimental determinations of universal quantities is
presented.Comment: 65 pages, 1 figure, revtex. New Monte Carlo data by Hasenbusch
enabled us to improve the determination of the critical exponents and of the
equation of state. The discussion of several topics was improved and the
bibliography was update
A Complete Set of Local Invariants for a Family of Multipartite Mixed States
We study the equivalence of quantum states under local unitary
transformations by using the singular value decomposition. A complete set of
invariants under local unitary transformations is presented for several classes
of tripartite mixed states in KxMxN composite systems. Two density matrices in
the same class are equivalent under local unitary transformations if and only
if all these invariants have equal values for these density matrices.Comment: 10 page
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