4,763 research outputs found

    Default mode network connectivity and reciprocal social behavior in 22q11.2 deletion syndrome

    Get PDF
    22q11.2 deletion syndrome (22q11DS) is a genetic mutation associated with disorders of cortical connectivity and social dysfunction. However, little is known about the functional connectivity (FC) of the resting brain in 22q11DS and its relationship with social behavior. A seed-based analysis of resting-state functional magnetic resonance imaging data was used to investigate FC associated with the posterior cingulate cortex (PCC), in (26) youth with 22qDS and (51) demographically matched controls. Subsequently, the relationship between PCC connectivity and Social Responsiveness Scale (SRS) scores was examined in 22q11DS participants. Relative to 22q11DS participants, controls showed significantly stronger FC between the PCC and other default mode network (DMN) nodes, including the precuneus, precentral gyrus and left frontal pole. 22q11DS patients did not show age-associated FC changes observed in typically developing controls. Increased connectivity between PCC, medial prefrontal regions and the anterior cingulate cortex, was associated with lower SRS scores (i.e. improved social competence) in 22q11DS. DMN integrity may play a key role in social information processing. We observed disrupted DMN connectivity in 22q11DS, paralleling reports from idiopathic autism and schizophrenia. Increased strength of long-range DMN connectivity was associated with improved social functioning in 22q11DS. These findings support a \u27developmental-disconnection\u27 hypothesis of symptom development in this disorder

    High pressure evolution of Fe2_{2}O3_{3} electronic structure revealed by X-ray absorption

    Full text link
    We report the first high pressure measurement of the Fe K-edge in hematite (Fe2_2O3_3) by X-ray absorption spectroscopy in partial fluorescence yield geometry. The pressure-induced evolution of the electronic structure as Fe2_2O3_3 transforms from a high-spin insulator to a low-spin metal is reflected in the x-ray absorption pre-edge. The crystal field splitting energy was found to increase monotonically with pressure up to 48 GPa, above which a series of phase transitions occur. Atomic multiplet, cluster diagonalization, and density-functional calculations were performed to simulate the pre-edge absorption spectra, showing good qualitative agreement with the measurements. The mechanism for the pressure-induced phase transitions of Fe2_2O3_3 is discussed and it is shown that ligand hybridization significantly reduces the critical high-spin/low-spin pressure.Comment: 5 pages, 4 figures and 1 tabl

    A randomised, double-blind, phase 3 study comparing the efficacy and safety of ceftazidime/avibactam plus metronidazole versus meropenem for complicated intra-abdominal infections in hospitalised adults in Asia

    Get PDF
    Ceftazidime/avibactam comprises the broad-spectrum cephalosporin ceftazidime and the non-β-lactam β-lactamase inhibitor avibactam. This phase 3, randomised, double-blind study (NCT01726023) assessed the efficacy and safety of ceftazidime/avibactam plus metronidazole compared with meropenem in patients with complicated intra-abdominal infection (cIAI) in Asian countries. Subjects aged 18–90 years and hospitalised with cIAI requiring surgical intervention were randomised 1:1 to receive every 8 h either: ceftazidime/avibactam (2000/500 mg, 2-h infusion) followed by metronidazole (500 mg, 60-min infusion); or meropenem (1000 mg, 30-min infusion). Non-inferiority of ceftazidime/avibactam plus metronidazole to meropenem was concluded if the lower limit of the 95% confidence interval (CI) for the between-group difference in clinical cure rate was greater than −12.5% at the test-of-cure (TOC) visit (28–35 days after randomisation) in the clinically evaluable (CE) population. Safety was also evaluated. Of 441 subjects randomised, 432 received at least one dose of study medication (ceftazidime/avibactam plus metronidazole, n = 215; meropenem, n = 217). In the CE population at the TOC visit, non-inferiority of ceftazidime/avibactam plus metronidazole to meropenem was demonstrated, with clinical cure reported for 93.8% (166/177) and 94.0% (173/184) of subjects, respectively (between-group difference, −0.2, 95% CI −5.53 to 4.97). The clinical cure rate with ceftazidime/avibactam plus metronidazole was comparable in subjects with ceftazidime-non-susceptible and ceftazidime-susceptible isolates (95.7% vs. 92.1%, respectively). Adverse events were similar between the study groups. Ceftazidime/avibactam plus metronidazole was non-inferior to meropenem in the treatment of cIAIs in Asian populations and was effective against ceftazidime-non-susceptible pathogens. No new safety concerns were identified

    Multi-threshold second-order phase transition

    Get PDF
    We present a theory of the multi-threshold second-order phase transition, and experimentally demonstrate the multi-threshold second-order phase transition phenomenon. With carefully selected parameters, in an external cavity diode laser system, we observe second-order phase transition with multiple (three or four) thresholds in the measured power-current-temperature three dimensional phase diagram. Such controlled death and revival of second-order phase transition sheds new insight into the nature of ubiquitous second-order phase transition. Our theory and experiment show that the single threshold second-order phase transition is only a special case of the more general multi-threshold second-order phase transition, which is an even richer phenomenon.Comment: 5 pages, 3 figure

    Changes in photosynthetic pigments and chlorophyll fluorescence parameters in the super-high-yielding rice hybrid Peiai64S/E32 during senescence

    Get PDF
    The hybrid rice (Oryza sativa L.) cultivar Peiai64S/E32, which is a hybrid of E32 and Peiai64S, has a super high yield compared with that of its parents. Changes in photosynthetic pigments and chlorophyll (Chl) fluorescence parameters were investigated in the flag leaves during senescence. The content of Chl and carotenoids in the flag leaves of Peiai64S/E32 was more stable than those of their parents during senescence. Furthermore, Peiai64S/E32 had a more stable PSII activity and a lower nonphotochemical quenching and deepoxidation state than that of its parents in the later stage of senescence. These results demonstrated that Peiai64S/E32 functioned longer than its parents did during the leaf senescence and grain-filling period. This occurred because there was more excitation energy to drive photosynthetic CO2 fixation in Peiai64S/E32, as the pigments supplying the energy survived longer in the high-yielding rice compared to the parents

    Formal matched asymptotics for degenerate Ricci flow neckpinches

    Full text link
    Gu and Zhu have shown that Type-II Ricci flow singularities develop from nongeneric rotationally symmetric Riemannian metrics on SmS^m, for all m3m\geq 3. In this paper, we describe and provide plausibility arguments for a detailed asymptotic profile and rate of curvature blow-up that we predict such solutions exhibit

    Predictions for s-Wave and p-Wave Heavy Baryons from Sum Rules and Constituent Quark Model (I): Strong Interactions

    Full text link
    We study the strong interactions of the L=1 orbitally excited baryons with one heavy quark in the framework of the Heavy Hadron Chiral Perturbation Theory. To leading order in the heavy mass expansion, the interaction Lagrangian describing the couplings of these states among themselves and with the ground state heavy baryons contains 46 unknown couplings. We derive sum rules analogous to the Adler-Weisberger sum rule which constrain these couplings and relate them to the couplings of the s-wave heavy baryons. Using a spin 3/2 baryon as a target, we find a sum rule expressing the deviation from the quark model prediction for pion couplings to s-wave states in terms of couplings of the p-wave states. In the constituent quark model these couplings are related and can be expressed in terms of only two reduced matrix elements. Using recent CLEO data on Σc\Sigma_c^{*} and Λc1+\Lambda_{c1}^+ strong decays, we determine some of the unknown couplings in the chiral Lagrangian and the two quark model reduced matrix elements. Specific predictions are made for the decay properties of all L=1 charmed baryons.Comment: 50 pages, REVTeX with 4 included figures; predictions for additional decay modes included; 1 reference adde

    On a sharp volume estimate for gradient Ricci solitons with scalar curvature bounded below

    Full text link
    In this note, we obtain a sharp volume estimate for complete gradient Ricci solitons with scalar curvature bounded below by a positive constant. Using Chen-Yokota's argument we obtain a local lower bound estimate of the scalar curvature for the Ricci flow on complete manifolds. Consequently, one has a sharp estimate of the scalar curvature for expanding Ricci solitons; we also provide a direct (elliptic) proof of this sharp estimate. Moreover, if the scalar curvature attains its minimum value at some point, then the manifold is Einstein.Comment: 15 pages. Added some references and an appendix to give a more simple computation of the volume estimat

    Baryonium, tetra-quark state and glue-ball in large N_c QCD

    Full text link
    From the large-N_c QCD point of view, baryonia, tetra-quark states, hybrids, and glueballs are studied. The existence of these states is argued for. They are constructed from baryons. In N_f=1 large N_c QCD, a baryonium is always identical to a glueball with N_c valence gluons. The ground state 0^{-+} glueball has a mass about 2450 MeV. f_0(1710) is identified as the lowest 0^{++} glueball. The lowest four-quark nonet should be f_0(1370), a_0(1450), K^*_0(1430) and f_0(1500). Combining with the heavy quark effective theory, spectra of heavy baryonia and heavy tetra-quark states are predicted. 1/N_c corrections are discussed.Comment: 16 pages, 3 figure
    corecore