1,622 research outputs found
Period Integrals of CY and General Type Complete Intersections
We develop a global Poincar\'e residue formula to study period integrals of
families of complex manifolds. For any compact complex manifold equipped
with a linear system of generically smooth CY hypersurfaces, the formula
expresses period integrals in terms of a canonical global meromorphic top form
on . Two important ingredients of our construction are the notion of a CY
principal bundle, and a classification of such rank one bundles. We also
generalize our construction to CY and general type complete intersections. When
is an algebraic manifold having a sufficiently large automorphism group
and is a linear representation of , we construct a holonomic D-module
that governs the period integrals. The construction is based in part on the
theory of tautological systems we have developed in the paper \cite{LSY1},
joint with R. Song. The approach allows us to explicitly describe a
Picard-Fuchs type system for complete intersection varieties of general types,
as well as CY, in any Fano variety, and in a homogeneous space in particular.
In addition, the approach provides a new perspective of old examples such as CY
complete intersections in a toric variety or partial flag variety.Comment: An erratum is included to correct Theorem 3.12 (Uniqueness of CY
structure
Information system for monitoring and assessing stress among medical students
Author ProofThe severe or prolonged exposure to stress-inducing factors in occupational and academic settings is a growing concern. The literature describes several potentially stressful moments experienced by medical students throughout the course, affecting cognitive functioning and learning. In this paper, we introduce the EUSTRESS Solution, that aims to create an Information System to monitor and assess, continuously and in real-time, the stress levels of the individuals in order to predict chronic stress. The Information System will use a measuring instrument based on wearable devices and machine learning techniques to collect and process stress-related data from the individual without his/her explicit interaction. A big database has been built through physiological, psychological, and behavioral assessments of medical students. In this paper, we focus on heart rate and heart rate variability indices, by comparing baseline and stress condition. In order to develop a predictive model of stress, we performed different statistical tests. Preliminary results showed the neural network had the better model fit. As future work, we will integrate salivary samples and self-report questionnaires in order to develop a more complex and intelligent model.QVida+ project (Estimação Contínua de Qualidade de Vida para Auxílio Eficaz à Decisão Clínica), funded by European Structural funds (FEDER-003446), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement
Infrared spectroscopy and nano-imaging of the insulator-to-metal transition in vanadium dioxide
We present a detailed infrared study of the insulator-to-metal transition
(IMT) in vanadium dioxide (VO2) thin films. Conventional infrared spectroscopy
was employed to investigate the IMT in the far-field. Scanning near-field
infrared microscopy directly revealed the percolative IMT with increasing
temperature. We confirmed that the phase transition is also percolative with
cooling across the IMT. We present extensive near-field infrared images of
phase coexistence in the IMT regime in VO2. We find that the coexisting
insulating and metallic regions at a fixed temperature are static on the time
scale of our measurements. A novel approach for analyzing the far-field and
near-field infrared data within the Bruggeman effective medium theory was
employed to extract the optical constants of the incipient metallic puddles at
the onset of the IMT. We found divergent effective carrier mass in the metallic
puddles that demonstrates the importance of electronic correlations to the IMT
in VO2. We employ the extended dipole model for a quantitative analysis of the
observed near-field infrared amplitude contrast and compare the results with
those obtained with the basic dipole model.Comment: 18 pages including 8 figure
RadioAstron Space VLBI Imaging of the jet in M87: I. Detection of high brightness temperature at 22 GHz
We present results from the first 22 GHz space very-long-baseline
interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of
the Nearby AGN Key Science Program, the source was observed in Feb 2014 at 22
GHz with 21 ground stations, reaching projected -spacings up to
G. The imaging experiment was complemented by snapshot
RadioAstron data of M87 obtained during 2013--2016 from the AGN Survey Key
Science Program. Their longest baselines extend up to G. For
all these measurements, fringes are detected only up to 2.8 Earth
Diameter or 3 G baseline lengths, resulting in a new image with
angular resolution of as or Schwarzschild radii spatial
resolution. The new image not only shows edge-brightened jet and counterjet
structures down to submilliarcsecond scales but also clearly resolves the VLBI
core region. While the overall size of the core is comparable to those reported
in the literature, the ground-space fringe detection and slightly
super-resolved RadioAstron image suggest the presence of substructures in the
nucleus, whose minimum brightness temperature exceeds K. It is challenging to explain the origin of this
record-high value for M87 by pure Doppler boosting effect with
a simple conical jet geometry and known jet speed. Therefore, this can be
evidence for more extreme Doppler boosting due to a blazar-like small jet
viewing angle or highly efficient particle acceleration processes occurring
already at the base of the outflow.Comment: 27 pages, 13 figures, accepted for publication in Ap
External antenna design for GPS signal reception enhancement
The working paper explains the detailed analysis of the low-cost design and implementation of 53.0 × 41.0 mm Single Microstrip Patch Antenna (SMPA) for handheld Global Positioning System (GPS) receiver external use. A Computer Simulation Technology (CST) microwave studio technique was applied, using the dielectric of 5.0 and substrate thickness of 1.6 mm. The SMPA designed for data acquisition application operating on a single frequency on 1.57542 GHz. The antenna gain enhancement and the signal reception have improved the receiver line-of-sight (LOS) for an indoors experimental usage. However, the external antenna gain overcomes raw data quality degradation caused by the internal antenna due to low elevation angle and results in non LO
A Systematic Literature Review Analysis of Ultrasound Joint Count and Scoring Systems to Assess Synovitis in Rheumatoid Arthritis According to the OMERACT Filter
Objective. The OMERACT Ultrasound Task Force is currently developing a global synovitis score (GLOSS) with the objective of feasibly measuring global disease activity in patients with rheumatoid arthritis (RA). In order to determine the minimal number of joints to be included in such a scoring system, and to analyze the metric properties of proposed global (i.e., patient level) ultrasound (US) scoring systems of synovitis in RA, a systematic analysis of the literature was performed. Methods. A systematic literature search of Pubmecl and Embase was performed (January 1, 1984, to March 31, 2010). Original research reports written in English including RA, ultrasound, Doppler, and scoring systems were included. The design, subjects, methods, imaging protocols, and performance characteristics studied were analyzed, as well as the ultrasound definition of synovitis. Results. Of 3004 reports identified, 14 articles were included in the review. We found a lack of clear definition of synovitis as well as varying validity data with respect to the proposed scores. Scoring systems included a wide range and number of joints. All analyzed studies assessed construct validity and responsiveness by using clinical examination, laboratory findings, and other imaging modalities as comparators. Both construct validity and responsiveness varied according to the number and size of joints examined and according to the component of synovitis measured [i.e., gray-scale (GS) or power Doppler (PD) alone or in combination]. With regard to feasibility, time of evaluation varied from 15 to 60 min and increased with the number of joints involved in the examination. Conclusions. Ultrasound can be regarded as a valuable tool for globally examining the extent of synovitis in RA. However, it is presently difficult to determine a minimal number of joints to be included in a global ultrasound score. Further validation of proposed scores is needed. (J Rheumatol 2011; 38:2055-62; doi:10.3899/jrheum.110424
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Refining the accuracy of validated target identification through coding variant fine-mapping in type 2 diabetes.
We aggregated coding variant data for 81,412 type 2 diabetes cases and 370,832 controls of diverse ancestry, identifying 40 coding variant association signals (P < 2.2 × 10-7); of these, 16 map outside known risk-associated loci. We make two important observations. First, only five of these signals are driven by low-frequency variants: even for these, effect sizes are modest (odds ratio ≤1.29). Second, when we used large-scale genome-wide association data to fine-map the associated variants in their regional context, accounting for the global enrichment of complex trait associations in coding sequence, compelling evidence for coding variant causality was obtained for only 16 signals. At 13 others, the associated coding variants clearly represent 'false leads' with potential to generate erroneous mechanistic inference. Coding variant associations offer a direct route to biological insight for complex diseases and identification of validated therapeutic targets; however, appropriate mechanistic inference requires careful specification of their causal contribution to disease predisposition
International consensus for ultrasound lesions in gout: Results of delphi process and web-reliability exercise
Objective. To produce consensus-based definitions of the US elementary lesions in gout and to test their reliability in a web-based exercise. Methods. The process consisted of two steps. In the first step a written Delphi questionnaire was developed from a systematic literature review and expert international consensus. This collated information resulted in four statements defining US elementary lesions: double contour (DC), tophus, aggregates and erosion. The Delphi questionnaire was sent to 35 rheumatology experts in US, asking them to rate their level of agreement or disagreement with each statement. The second step tested the reliability by a web-exercise. US images of both normal and gouty elementary lesions were collected by the participants. A facilitator then constructed an electronic database of 110 images. The database was sent to the participants, who evaluated the presence/absence of US elementary lesions. A group of 20 images was displayed twice to evaluate intra-reader reliability. Results. A total of 32 participants responded to the questionnaires. Good agreement (>80%) was obtained for US definitions on DC, tophus, aggregates and erosion in the Delphi exercise after three rounds. The reliability on images showed inter-reader κ values for DC, tophus, aggregates, erosion findings of 0.98, 0.71, 0.54 and 0.85, respectively. The mean intra-reader κ values were also acceptable: 0.93, 0.78, 0.65 and 0.78, respectively. Conclusion. This, the first consensus-based US definition of elementary lesions in gout, demonstrated good reliability overall. It constitutes an essential step in developing a core outcome measurement that permits a higher degree of homogeneity and comparability between multicentre studies
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