15,370 research outputs found
Some triviality results for quasi-Einstein manifolds and Einstein warped products
In this paper we prove a number of triviality results for Einstein warped
products and quasi-Einstein manifolds using different techniques and under
assumptions of various nature. In particular we obtain and exploit gradient
estimates for solutions of weighted Poisson-type equations and adaptations to
the weighted setting of some Liouville-type theorems.Comment: 15 pages, fixed minor mistakes in Section
Dietary patterns, insulin sensitivity and inflammation in older adults.
Background/objectivesSeveral studies have linked dietary patterns to insulin sensitivity and systemic inflammation, which affect risk of multiple chronic diseases. The purpose of this study was to investigate the dietary patterns of a cohort of older adults, and to examine relationships of dietary patterns with markers of insulin sensitivity and systemic inflammation.Subjects/methodsThe Health, Aging and Body Composition (Health ABC) Study is a prospective cohort study of 3075 older adults. In Health ABC, multiple indicators of glucose metabolism and systemic inflammation were assessed. Food intake was estimated with a modified Block food frequency questionnaire. In this study, dietary patterns of 1751 participants with complete data were derived by cluster analysis.ResultsSix clusters were identified, including a 'healthy foods' cluster, characterized by higher intake of low-fat dairy products, fruit, whole grains, poultry, fish and vegetables. In the main analysis, the 'healthy foods' cluster had significantly lower fasting insulin and homeostasis model assessment of insulin resistance values than the 'breakfast cereal' and 'high-fat dairy products' clusters, and lower fasting glucose than the 'high-fat dairy products' cluster (P≤0.05). No differences were found in 2-h glucose. With respect to inflammation, the 'healthy foods' cluster had lower interleukin-6 than the 'sweets and desserts' and 'high-fat dairy products' clusters, and no differences were seen in C-reactive protein or tumor necrosis factor-α.ConclusionsA dietary pattern high in low-fat dairy products, fruit, whole grains, poultry, fish and vegetables may be associated with greater insulin sensitivity and lower systemic inflammation in older adults
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Endocardial ablation of ventricular ectopic beats arising from the basal inferoseptal process of the left ventricle
Background
Idiopathic ventricular ectopy (VE) shows predilection to sites within the left ventricular (LV) base such as the outflow tract/aortic sinuses, LV summit, and areas adjacent to the aortomitral continuity. We characterize VE arising from the inferior septum of the LV base that was successfully managed by LV endocardial ablation from the inferoseptal recess of the LV.
Objective
The purpose of this study was to determine the incidence, electrocardiographic (ECG) findings, electrophysiological findings, and anatomical features associated with VE arising from the basal inferoseptal process of the LV (ISP-LV) ablated using an LV endocardial approach via the inferoseptal recess of the LV.
Methods
A total of 425 consecutive patients undergoing VE ablation between January 1, 2012 and December 31, 2016 at 3 centers were evaluated. Demographic characteristics, ECG findings, and procedural data were analyzed for patients with ISP-LV VEs.
Results
Seven (1.5%) had a site of origin from the ISP-LV. Common ECG findings were a right bundle branch block concordant pattern or an atypical left bundle branch block early transition pattern, suggestive of a basal origin with a left superior axis, a biphasic QRS complex in lead aVR, and a small s wave in lead V6. Earliest activation was seen in an area below the outflow tract accessed from the inferoseptal recess inferior to the His bundle. In 3 cases, transient junctional rhythm was seen during ablation. All cases were ablated successfully with no complications.
Conclusion
VE arising from the ISP-LV represents a distinct subset of idiopathic arrhythmia and can be successfully treated by endocardial catheter ablation from the inferoseptal recess. They share common surface ECG and electrophysiological findings with special anatomical features that need recognition for successful catheter ablation
The analysis of European lacquer : optimization of thermochemolysis temperature of natural resins
In order to optimize chromatographic analysis of European lacquer, thermochemolysis temperature was evaluated for the analysis of natural resins. Five main ingredients of lacquer were studied: sandarac, mastic, colophony, Manila copal and Congo copal. For each, five temperature programs were tested: four fixed temperatures (350, 480, 550, 650 degrees C) and one ultrafast thermal desorption (UFD), in which the temperature rises from 350 to 660 degrees C in 1 min. In total, the integrated signals of 27 molecules, partially characterizing the five resins, were monitored to compare the different methods. A compromise between detection of compounds released at low temperatures and compounds formed at high temperatures was searched. 650 degrees C is too high for both groups, 350 degrees C is best for the first, and 550 degrees C for the second. Fixed temperatures of 480 degrees C or UFD proved to be a consensus in order to detect most marker molecules. UFD was slightly better for the molecules released at low temperatures, while 480 degrees C showed best compounds formed at high temperatures
Quantum spin liquid states in the two dimensional kagome antiferromagnets, ZnxCu4-x(OD)6Cl2
A three-dimensional system of interacting spins typically develops static
long-range order when it is cooled. If the spins are quantum (S = 1/2),
however, novel quantum paramagnetic states may appear. The most highly sought
state among them is the resonating valence bond (RVB) state in which every pair
of neighboring quantum spins form entangled spin singlets (valence bonds) and
the singlets are quantum mechanically resonating amongst all the possible
highly degenerate pairing states. Here we provide experimental evidence for
such quantum paramagnetic states existing in frustrated antiferromagnets,
ZnxCu4-x(OD)6Cl2, where the S = 1/2 magnetic Cu2+ moments form layers of a
two-dimensional kagome lattice. We find that in Cu4(OD)6Cl2, where distorted
kagome planes are weakly coupled to each other, a dispersionless excitation
mode appears in the magnetic excitation spectrum below ~ 20 K, whose
characteristics resemble those of quantum spin singlets in a solid state, known
as a valence bond solid (VBS), that breaks translational symmetry. Doping
nonmagnetic Zn2+ ions reduces the distortion of the kagome lattice, and weakens
the interplane coupling but also dilutes the magnetic occupancy of the kagome
lattice. The VBS state is suppressed and for ZnCu3(OD)6Cl2 where the kagome
planes are undistorted and 90% occupied by the Cu2+ ions, the low energy spin
fluctuations in the spin liquid phase become featureless
Phase-slip induced dissipation in an atomic Bose-Hubbard system
Phase slips play a primary role in dissipation across a wide spectrum of
bosonic systems, from determining the critical velocity of superfluid helium to
generating resistance in thin superconducting wires. This subject has also
inspired much technological interest, largely motivated by applications
involving nanoscale superconducting circuit elements, e.g., standards based on
quantum phase-slip junctions. While phase slips caused by thermal fluctuations
at high temperatures are well understood, controversy remains over the role of
phase slips in small-scale superconductors. In solids, problems such as
uncontrolled noise sources and disorder complicate the study and application of
phase slips. Here we show that phase slips can lead to dissipation for a clean
and well-characterized Bose-Hubbard (BH) system by experimentally studying
transport using ultra-cold atoms trapped in an optical lattice. In contrast to
previous work, we explore a low velocity regime described by the 3D BH model
which is not affected by instabilities, and we measure the effect of
temperature on the dissipation strength. We show that the damping rate of
atomic motion-the analogue of electrical resistance in a solid-in the confining
parabolic potential fits well to a model that includes finite damping at zero
temperature. The low-temperature behaviour is consistent with the theory of
quantum tunnelling of phase slips, while at higher temperatures a cross-over
consistent with the transition to thermal activation of phase slips is evident.
Motion-induced features reminiscent of vortices and vortex rings associated
with phase slips are also observed in time-of-flight imaging.Comment: published in Nature 453, 76 (2008
An inhibitory pull-push circuit in frontal cortex.
Push-pull is a canonical computation of excitatory cortical circuits. By contrast, we identify a pull-push inhibitory circuit in frontal cortex that originates in vasoactive intestinal polypeptide (VIP)-expressing interneurons. During arousal, VIP cells rapidly and directly inhibit pyramidal neurons; VIP cells also indirectly excite these pyramidal neurons via parallel disinhibition. Thus, arousal exerts a feedback pull-push influence on excitatory neurons-an inversion of the canonical push-pull of feedforward input
A test of general relativity from the three-dimensional orbital geometry of a binary pulsar
Binary pulsars provide an excellent system for testing general relativity
because of their intrinsic rotational stability and the precision with which
radio observations can be used to determine their orbital dynamics.
Measurements of the rate of orbital decay of two pulsars have been shown to be
consistent with the emission of gravitational waves as predicted by general
relativity, providing the most convincing evidence for the self-consistency of
the theory to date. However, independent verification of the orbital geometry
in these systems was not possible. Such verification may be obtained by
determining the orientation of a binary pulsar system using only classical
geometric constraints, permitting an independent prediction of general
relativistic effects. Here we report high-precision timing of the nearby binary
millisecond pulsar PSR J0437-4715, which establish the three-dimensional
structure of its orbit. We see the expected retardation of the pulse signal
arising from the curvature of space-time in the vicinity of the companion
object (the `Shapiro delay'), and we determine the mass of the pulsar and its
white dwarf companion. Such mass determinations contribute to our understanding
of the origin and evolution of neutron stars.Comment: 5 pages, 2 figure
Laccase: a green catalyst for the biosynthesis of poly-phenols
Laccases (benzene diol: oxidoreductases, EC 1.10.3.2) are able to catalyze the oxidation of various compounds containing phenolic and aniline structures using dissolved oxygen in water. Laccase structural features and catalytic mechanisms focused on the polymerization of aromatic compounds are reported. A description about the most recent research on the biosynthesis of chemicals and polymers is made. Selected applications of this technology are considered as well as the advantages, shortcomings and future needs related with the use of laccases.This study was supported by Chinese Government Scholarship under China Scholarship Council (No. 201606790036) and Chinese Foundation Key projects of governmental cooperation in international scientific and technological innovation (No. 2016 YFE0115700). The authors would also like to acknowledge Portuguese Foundation for Science and Technology (FCT) for the funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01–0145-FEDER-006684) and BioTecNorte operation (NORTE-01–0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio
Temporal trends in mode, site and stage of presentation with the introduction of colorectal cancer screening: a decade of experience from the West of Scotland
background: Population colorectal cancer screening programmes have been introduced to reduce cancer-specific mortality through the detection of early-stage disease. The present study aimed to examine the impact of screening introduction in the West of Scotland.
methods: Data on all patients with a diagnosis of colorectal cancer between January 2003 and December 2012 were extracted from a prospectively maintained regional audit database. Changes in mode, site and stage of presentation before, during and after screening introduction were examined.
results: In a population of 2.4 million, over a 10-year period, 14 487 incident cases of colorectal cancer were noted. Of these, 7827 (54%) were males and 7727 (53%) were socioeconomically deprived. In the postscreening era, 18% were diagnosed via the screening programme. There was a reduction in both emergency presentation (20% prescreening vs 13% postscreening, P0.001) and the proportion of rectal cancers (34% prescreening vs 31% pos-screening, P0.001) over the timeframe. Within non-metastatic disease, an increase in the proportion of stage I tumours at diagnosis was noted (17% prescreening vs 28% postscreening, P0.001).
conclusions: Within non-metastatic disease, a shift towards earlier stage at diagnosis has accompanied the introduction of a national screening programme. Such a change should lead to improved outcomes in patients with colorectal cancer
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