9,867 research outputs found
Exact Study of the 1D Boson Hubbard Model with a Superlattice Potential
We use Quantum Monte Carlo simulations and exact diagonalization to explore
the phase diagram of the Bose-Hubbard model with an additional superlattice
potential. We first analyze the properties of superfluid and insulating phases
present in the hard-core limit where an exact analytic treatment is possible
via the Jordan-Wigner transformation. The extension to finite on-site
interaction is achieved by means of quantum Monte Carlo simulations. We
determine insulator/superfluid phase diagrams as functions of the on-site
repulsive interaction, superlattice potential strength, and filling, finding
that insulators with fractional occupation numbers, which are present in the
hard-core case, extend deep into the soft-core region. Furthermore, at integer
fillings, we find that the competition between the on-site repulsion and the
superlattice potential can produce a phase transition between a Mott insulator
and a charge density wave insulator, with an intermediate superfluid phase. Our
results are relevant to the behavior of ultracold atoms in optical
superlattices which are beginning to be studied experimentally.Comment: 13 pages, 23 figure
Trisomy 19 ependymoma, a newly recognized genetico-histological association, including clear cell ependymoma
Ependymal tumors constitute a clinicopathologically heterogeneous group of brain tumors. They vary in regard to their age at first symptom, localization, morphology and prognosis. Genetic data also suggests heterogeneity. We define a newly recognized subset of ependymal tumors, the trisomy 19 ependymoma. Histologically, they are compact lesions characterized by a rich branched capillary network amongst which tumoral cells are regularly distributed. When containing clear cells they are called clear cell ependymoma. Most trisomy 19 ependymomas are supratentorial WHO grade III tumors of the young. Genetically, they are associated with trisomy 19, and frequently with a deletion of 13q21.31-31.2, three copies of 11q13.3-13.4, and/or deletions on chromosome 9. These altered chromosomal regions are indicative of genes and pathways involved in trisomy 19 ependymoma tumorigenesis. Recognition of this genetico-histological entity allows better understanding and dissection of ependymal tumors
Peran Desentralisasi Fiskal Terhadap Kinerja Ekonomi Di Kabupaten/kota Provinsi Jawa Tengah
This research is intended to examine the influence of fiscal decentralization on economic growth, poverty, employment, and welfare at regencies/municipalities level in Central Java Province. Research population consist of 29 regencies and 6 municipalities, employing secondary data from Central Bureau of Statistic of Central Java Province and regencies/municipalities level in Central Java Province within the period of 2001 up to 2005. Data analysis is conducted by using path analysis with AMOS program software. The results of this study indicate that, first fiscal decentralization has a positive and significant effect on economic growth. Second, economic growth has a positive and significant effect on employment rate. Third, economic growth has a negative and significant effect on poverty. Forth, economic growth has a positive and significant effect on welfare. Fifth, employment rate has a negative and significant effect on welfare. Sixth, poverty has a negative and significant effect on welfare at regencies/municipalities level in Central Java Province
Probing DNA conformational changes with high temporal resolution by Tethered Particle Motion
The Tethered Particle Motion (TPM) technique informs about conformational
changes of DNA molecules, e.g. upon looping or interaction with proteins, by
tracking the Brownian motion of a particle probe tethered to a surface by a
single DNA molecule and detecting changes of its amplitude of movement. We
discuss in this context the time resolution of TPM, which strongly depends on
the particle-DNA complex relaxation time, i.e. the characteristic time it takes
to explore its configuration space by diffusion. By comparing theory,
simulations and experiments, we propose a calibration of TPM at the dynamical
level: we analyze how the relaxation time grows with both DNA contour length
(from 401 to 2080 base pairs) and particle radius (from 20 to 150~nm). Notably
we demonstrate that, for a particle of radius 20~nm or less, the hydrodynamic
friction induced by the particle and the surface does not significantly slow
down the DNA. This enables us to determine the optimal time resolution of TPM
in distinct experimental contexts which can be as short as 20~ms.Comment: Improved version, to appear in Physical Biology. 10 pages + 10 pages
of supporting materia
Regional brain development analysis through registration using anisotropic similarity, a constrained affine transformation
We propose a novel method to quantify brain growth in 3 arbitrary orthogonal directions of the brain or its sub-regions through linear registration. This is achieved by introducing a 9 degrees of freedom (dof) transformation called anisotropic similarity which is an affine transformation with constrained scaling directions along arbitrarily chosen orthogonal vectors. This gives the opportunity to extract scaling factors describing brain growth along those directions by registering a database of subjects onto a common reference. This information about directional growth brings insights that are not usually available in longitudinal volumetric analysis. The interest of this method is illustrated by studying the anisotropic regional and global brain development of 308 healthy subjects betwen 0 and 19 years old. A gender comparison of those scaling factors is also performed for four age-intervals. We demonstrate through these applications the stability of the method to the chosen reference and its ability to highlight growth differences accros regions and gender
Determinants of physicians’ intention to collect data exhaustively in registries: an exploratory study in Bamako’s community health centres
Background: The incomplete collection of health datais a prevalent problem in healthcare systems around theworld, especially in developing countries. Missing datahinders progress in population health and perpetuatesinefficiencies in healthcare systems.Objective: This study aims to identify the factors that predict the intention of physicians practicing in community health centres of Bamako, Mali, to collect data exhaustively in medical registries.Design: A cross sectional studyMethod: In January and February 2011, we conducted a study with a random sample of thirty two physicians practicing in community health centres of Bamako, using a questionnaire. Data was analyzed by using descriptive statistics, correlations and linear regression.Main outcomes measures: Trained investigators administered a questionnaire measuring physicians’ sociodemographic and professional characteristics as well as constructs from the Theory of Planned Behaviour.Results: Our results showed that physicians’ intention to collect data exhaustively is influenced by subjective norms and by the physician’s number of years in practice.Conclusions: the results of this study could be used as a guide for health workers and decision makers to improve the quality of health information collected in community health centers.Keywords: Physicians’ intention, exhaustive data collection, Bamako, Community Health Centre, Missing dat
Impact of thermodiffusion on the initial vertical distribution of species in hydrocarbon reservoirs
High-sensitivity optical monitoring of a micro-mechanical resonator with a quantum-limited optomechanical sensor
We experimentally demonstrate the high-sensitivity optical monitoring of a
micro-mechanical resonator and its cooling by active control. Coating a
low-loss mirror upon the resonator, we have built an optomechanical sensor
based on a very high-finesse cavity (30000). We have measured the thermal noise
of the resonator with a quantum-limited sensitivity at the 10^-19 m/rootHz
level, and cooled the resonator down to 5K by a cold-damping technique.
Applications of our setup range from quantum optics experiments to the
experimental demonstration of the quantum ground state of a macroscopic
mechanical resonator.Comment: 4 pages, 5 figure
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