1,869 research outputs found

    Velocity-selective direct frequency-comb spectroscopy of atomic vapors

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    We present an experimental and theoretical investigation of two-photon direct frequency-comb spectroscopy performed through velocity-selective excitation. In particular, we explore the effect of repetition rate on the 5S1/2→5D3/2,5/2\textrm{5S}_{1/2}\rightarrow \textrm{5D}_{3/2, 5/2} two-photon transitions excited in a rubidium atomic vapor cell. The transitions occur via step-wise excitation through the 5P1/2,3/2\textrm{5P}_{1/2, 3/2} states by use of the direct output of an optical frequency comb. Experiments were performed with two different frequency combs, one with a repetition rate of ≈925\approx 925 MHz and one with a repetition rate of ≈250\approx 250 MHz. The experimental spectra are compared to each other and to a theoretical model.Comment: 10 pages, 7 figure

    Trisomy 19 ependymoma, a newly recognized genetico-histological association, including clear cell ependymoma

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    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

    Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn5_5: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state

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    We report high magnetic field linear magnetostriction experiments on CeCoIn5_5 single crystals. Two features are remarkable: (i) a sharp discontinuity in all the crystallographic axes associated with the upper superconducting critical field Bc2B_{c2} that becomes less pronounced as the temperature increases; (ii) a distinctive second order-like feature observed only along the c-axis in the high field (10 T ≲B≤Bc2 \lesssim B \leq B_{c2}) low temperature (T≲T \lesssim 0.35 K) region. This second order transition is observed only when the magnetic field lies within 20o^o of the ab-planes and there is no signature of it above Bc2B_{c2}, which raises questions regarding its interpretation as a field induced magnetically ordered phase. Good agreement with previous results suggests that this anomaly is related to the transition to the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state.Comment: 3 figures, 5 page

    An Experimental and Semi-Empirical Method to Determine the Pauli-Limiting Field in Quasi 2D Superconductors as applied to κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2: Strong Evidence of a FFLO State

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    We present upper critical field data for κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2 with the magnetic field close to parallel and parallel to the conducting layers. We show that we can eliminate the effect of vortex dynamics in these layered materials if the layers are oriented within 0.3 degrees of parallel to the applied magnetic field. Eliminating vortex effects leaves one remaining feature in the data that corresponds to the Pauli paramagnetic limit (HpH_p). We propose a semi-empirical method to calculate the HpH_p in quasi 2D superconductors. This method takes into account the energy gap of each of the quasi 2D superconductors, which is calculated from specific heat data, and the influence of many body effects. The calculated Pauli paramagnetic limits are then compared to critical field data for the title compound and other organic conductors. Many of the examined quasi 2D superconductors, including the above organic superconductors and CeCoIn5_5, exhibit upper critical fields that exceed their calculated HpH_p suggesting unconventional superconductivity. We show that the high field low temperature state in κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2 is consistent with the Fulde Ferrell Larkin Ovchinnikov state.Comment: 8 pages, 9 figures, 10 years of dat

    The important role for intravenous iron in perioperative patient blood management in major abdominal surgery: a randomized controlled trial

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    Objective: To determine if preoperative intravenous (IV) iron improves outcomes in abdominal surgery patients. Summary Background Data: Preoperative iron deficiency anemia (IDA) occurs frequently; however if left untreated, increases the risk of blood transfusion allogeneic blood transfusion (ABT). Limited evidence supports IDA treatment with preoperative IV iron. This randomized controlled trial aimed to determine whether perioperative IV iron reduced the need for ABT. Methods: Between August 2011 and November 2014, 72 patients with IDA were assigned to receive either IV iron or usual care. The primary endpoint was incidence of ABT. Secondary endpoints were various hemoglobin (Hb) levels, change in Hb between time points, length of stay, iron status, morbidity, mortality, and quality of life 4 weeks postsurgery. Results: A 60% reduction in ABT was observed in the IV iron group compared with the usual care group (31.25% vs 12.5%). Hb values, although similar at randomization, improved by 0.8 g/dL with IV iron compared with 0.1 g/dL with usual care (P = 0.01) by the day of admission. The IV iron group had higher Hb 4 weeks after discharge compared with the usual care group (1.9 vs 0.9 g/dL, P = 0.01), and a shorter length of stay (7.0 vs 9.7 d, P = 0.026). There was no difference in discharge Hb levels, morbidity, mortality, or quality of life. Conclusions: Administration of perioperative IV iron reduces the need for blood transfusion, and is associated with a shorter hospital stay, enhanced restoration of iron stores, and a higher mean Hb concentration 4 weeks after surgery.Bernd Froessler, Peter Palm, Ingo Weber, Nicolette A. Hodyl, Rajvinder Singh and Elizabeth M. Murph

    Network information and connected correlations

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    Entropy and information provide natural measures of correlation among elements in a network. We construct here the information theoretic analog of connected correlation functions: irreducible NN--point correlation is measured by a decrease in entropy for the joint distribution of NN variables relative to the maximum entropy allowed by all the observed N−1N-1 variable distributions. We calculate the ``connected information'' terms for several examples, and show that it also enables the decomposition of the information that is carried by a population of elements about an outside source.Comment: 4 pages, 3 figure

    Assessment of efficacy and safety of the herbal medicinal product BNO 1016 in chronic rhinosinusitis

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    Background: The objective of this clinical trial (CRS-02) was to assess the efficacy, safety and tolerability of two dosages of the herbal medicinal product BNO 1016 (Sinupret extract) in patients with chronic rhinosinusitis (CRS). Methodology: 929 patients suffering from CRS were enrolled in this randomised placebo-controlled trial with a treatment period of 12 weeks. The primary endpoint was the mean Major Symptom Score (MSS) in week 8 and week 12 compared to placebo. Secondary endpoints included further MSS related parameters and responder rates over time. Pharmacoeconomic endpoints were also analysed. Finally, safety and tolerability were evaluated. Results: Sinupret extract was not superior over placebo regarding the primary endpoint. However, the results of the secondary endpoints showed a clear trend towards superior efficacy. Therefore, additional post-hoc sensitivity analyses were performed in patients with a baseline MSS > 9 and persistence of disease > 1 year diagnosed by specialists in otorhinolaryngology.Those patients significantly benefited from Sinupret extract. Therapy was superior for the primary endpoint analysis. Patients were less impaired with respect to work and daily activities. A good safety and tolerability of Sinupret extract was assured in all patients. Conclusions: Sinupret extract can safely be administered in patients with CRS. Although the primary endpoint of the study was not significant, a post-hoc subgroup analysis in patients whose disease was diagnosed by a specialist revealed a pronounced treatment effect. Effects in that subgroup were even stronger with longer disease persistence and stronger severity

    Pressure Evolution of a Field Induced Fermi Surface Reconstruction and of the Neel Critical Field in CeIn3

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    We report high-pressure skin depth measurements on the heavy fermion material CeIn3 in magnetic fields up to 64 T using a self-resonant tank circuit based on a tunnel diode oscillator. At ambient pressure, an anomaly in the skin depth is seen at 45 T. The field where this anomaly occurs decreases with applied pressure until approximately 1.0 GPa, where it begins to increase before merging with the antiferromagnetic phase boundary. Possible origins for this transport anomaly are explored in terms of a Fermi surface reconstruction. The critical magnetic field at which the Neel ordered phase is suppressed is also mapped as a function of pressure and extrapolates to the previous ambient pressure measurements at high magnetic fields and high pressure measurements at zero magnetic field.Comment: 15 pages, 5 figure

    Towards understanding the variability in biospheric CO2 fluxes:Using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2

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    Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at five selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world
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