1,440 research outputs found
Breathing Oscillations in Bose - Fermi Mixing Gases with Yb atoms in the Largely Prolate Deformed Traps
We study the breathing oscillations in bose-fermi mixtures with Yb isotopes
in the largely prolate deformed trap, which are realized by Kyoto group. We
choose the three combinations of the Yb isotopes, Yb170-Yb171, Yb170-Yb173 and
Yb174-Yb173, whose boson-fermion interactions are weakly repulsive, strongly
attractive and strongly repulsive. The collective oscillations in the deformed
trap are calculated in the dynamical time-development approach, which is
formulated with the time-dependent Gross-Pitaevskii and the Vlasov equations.
We analyze the results in the time-development approach with the intrinsic
oscillation modes of the deformed system, which are obtained using the scaling
method, and show that the damping and forced-oscillation effects of the
intrinsic modes give time-variation of oscillations, especially, in the fermion
transverse mode.Comment: 27 pages, 12 figure
Simulation of the many-body dynamical quantum Hall effect in an optical lattice
We propose an experimental scheme to simulate the many-body dynamical quantum
Hall effect with ultra-cold bosonic atoms in a one-dimensional optical lattice.
We first show that the required model Hamiltonian of a spin-1/2 Heisenberg
chain with an effective magnetic field and tunable parameters can be realized
in this system. For dynamical response to ramping the external fields, the
quantized plateaus emerge in the Berry curvature of the interacting atomic spin
chain as a function of the effective spin-exchange interaction. The
quantization of this response in the parameter space with the
interaction-induced topological transition characterizes the many-body
dynamical quantum Hall effect. Furthermore, we demonstrate that this phenomenon
can be observed in practical cold-atom experiments with numerical simulations.Comment: 8 pages, 3 figures; accepted in Quantum Information Processin
A practice-related risk score (PRS): a DOPPS-derived aggregate quality index for haemodialysis facilities
Background. The Dialysis Outcomes and Practice Patterns Study (DOPPS) database was used to develop and validate a practice-related risk score (PRS) based on modifiable practices to help facilities assess potential areas for improving patient care.
Methods. Relative risks (RRs) from a multivariable Cox mortality model, based on observational haemodialysis (HD) patient data from DOPPS I (1996-2001, seven countries), were used. The four practices were the percent of patients with Kt/V >= 1.2, haemoglobin >= 11 g/dl (110 g/l), albumin >= 4.0 g/dl (40g/l) and catheter use, and were significantly related to mortality when modelled together. DOPPS II data (2002-2004, 12 countries) were used to evaluate the relationship between PRS and mortality risk using Cox regression.
Results. For facilities in DOPPS I and II, changes in PRS over time were significantly correlated with changes in the standardized mortality ratio (SMR). The PRS ranged from 1.0 to 2.1. Overall, the adjusted RR of death was 1.05 per 0.1 points higher PRS (P < 0.0001). For facilities in both DOPPS I and II (N = 119), a 0.2 decrease in PRS was associated with a 0.19 decrease in SMR (P = 0.005). On average, facilities that improved PRS practices showed significantly reduced mortality over the same time frame.
Conclusions. The PRS assesses modifiable HD practices that are linked to improved patient survival. Further refinements might lead to improvements in the PRS and will address regional variations in the PRS/mortality relationship
Rhythmic expression of Nocturnin mRNA in multiple tissues of the mouse
BACKGROUND: Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis. Although encoding a novel protein, the nocturnin cDNA had strong sequence similarity with a C-terminal domain of the yeast transcription factor CCR4, and with mouse and human ESTs. Since its original identification others have cloned mouse and human homologues of nocturnin/CCR4, and we have cloned a full-length cDNA from mouse retina, along with partial cDNAs from human, cow and chicken. The goal of this study was to determine the temporal pattern of nocturnin mRNA expression in multiple tissues of the mouse. RESULTS: cDNA sequence analysis revealed a high degree of conservation among vertebrate nocturnin/CCR4 homologues along with a possible homologue in Drosophila. Northern analysis of mRNA in C3H/He and C57/Bl6 mice revealed that the mNoc gene is expressed in a broad range of tissues, with greatest abundance in liver, kidney and testis. mNoc is also expressed in multiple brain regions including suprachiasmatic nucleus and pineal gland. Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver. CONCLUSION: The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector
Changes in anemia management and hemoglobin levels following revision of a bundling policy to incorporate recombinant human erythropoietin
In April 2006, Japan's health insurance system instituted a bundling policy that included recombinant human erythropoietin (rHuEPO) in outpatient hemodialysis therapy. To evaluate outcomes of this, we analyzed a prospective cohort of hemodialysis patients in the Japan Dialysis Outcomes and Practice Patterns Study, in 53 facilities using prevalent cross-sections of 1584 patients before and 1622 patients after the rHuEPO reimbursement change. Patient data included hemoglobin levels, iron management profiles, and anemia treatment with rHuEPO and intravenous iron. No significant differences were found in pre- or post-policy cross-sections for hemoglobin distributions or the percentage of patients prescribed rHuEPO. Among patients receiving rHuEPO, the mean dose significantly decreased by 11.8 percent. The percentage of patients prescribed intravenous iron over 4months significantly increased; however, the mean dose of iron did not significantly change. Thus, this bundling policy was associated with reduced rHuEPO doses, increased intravenous iron use, and stable hemoglobin levels in Japanese patients receiving hemodialysis
Microscopic observation of magnon bound states and their dynamics
More than eighty years ago, H. Bethe pointed out the existence of bound
states of elementary spin waves in one-dimensional quantum magnets. To date,
identifying signatures of such magnon bound states has remained a subject of
intense theoretical research while their detection has proved challenging for
experiments. Ultracold atoms offer an ideal setting to reveal such bound states
by tracking the spin dynamics after a local quantum quench with single-spin and
single-site resolution. Here we report on the direct observation of two-magnon
bound states using in-situ correlation measurements in a one-dimensional
Heisenberg spin chain realized with ultracold bosonic atoms in an optical
lattice. We observe the quantum walk of free and bound magnon states through
time-resolved measurements of the two spin impurities. The increased effective
mass of the compound magnon state results in slower spin dynamics as compared
to single magnon excitations. In our measurements, we also determine the decay
time of bound magnons, which is most likely limited by scattering on thermal
fluctuations in the system. Our results open a new pathway for studying
fundamental properties of quantum magnets and, more generally, properties of
interacting impurities in quantum many-body systems.Comment: 8 pages, 7 figure
Divergence of the Grueneisen Ratio at Quantum Critical Points in Heavy Fermion Metals
We present low-temperature volume thermal expansion, , and specific
heat, , measurements on high-quality single crystals of CeNi2Ge2 and
YbRh2(SiGe) which are located very near to quantum
critical points. For both systems, shows a more singular temperature
dependence than , and thus the Grueneisen ratio
diverges as T --> 0. For CeNi2Ge2, our results are in accordance with the
spin-density wave (SDW) scenario for three-dimensional critical
spin-fluctuations. By contrast, the observed singularity in
YbRh2_{0.95}_{0.05}_2$ cannot be explained by the itinerant SDW
theory but is qualitatively consistent with a locally quantum critical picture.Comment: 11 pages, 4 figure
Measuring multipartite entanglement via dynamic susceptibilities
Entanglement plays a central role in our understanding of quantum many body
physics, and is fundamental in characterising quantum phases and quantum phase
transitions. Developing protocols to detect and quantify entanglement of
many-particle quantum states is thus a key challenge for present experiments.
Here, we show that the quantum Fisher information, representing a witness for
genuinely multipartite entanglement, becomes measurable for thermal ensembles
via the dynamic susceptibility, i.e., with resources readily available in
present cold atomic gas and condensed-matter experiments. This moreover
establishes a fundamental connection between multipartite entanglement and
many-body correlations contained in response functions, with profound
implications close to quantum phase transitions. There, the quantum Fisher
information becomes universal, allowing us to identify strongly entangled phase
transitions with a divergent multipartiteness of entanglement. We illustrate
our framework using paradigmatic quantum Ising models, and point out potential
signatures in optical-lattice experiments.Comment: 5+5 pages, 3+2 figure
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