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wave reflection

Diyendo Massilani, Silvia Guimaraes, Jean-Philip Brugal, E Andrew Bennett, Malgorzata Tokarska, Rose-Marie Arbogast, Gennady Baryshnikov, Gennady Boeskorov, Jean-Christophe Castel, Sergey Davydov, Stéphane Madelaine, Olivier Putelat, Natalia N Spasskaya, Hans-Peter Uerpmann, Thierry Grange, Eva-Maria Geigl
BACKGROUND: Climatic and environmental fluctuations as well as anthropogenic pressure have led to the extinction of much of Europe's megafauna. The European bison or wisent (Bison bonasus), one of the last wild European large mammals, narrowly escaped extinction at the onset of the 20th century owing to hunting and habitat fragmentation. Little is known, however, about its origin, evolutionary history and population dynamics during the Pleistocene. RESULTS: Through ancient DNA analysis we show that the emblematic European bison has experienced several waves of population expansion, contraction, and extinction during the last 50,000 years in Europe, culminating in a major reduction of genetic diversity during the Holocene...
October 21, 2016: BMC Biology
V L R Jacques, C Laulhé, N Moisan, S Ravy, D Le Bolloc'h
We report on time-resolved x-ray diffraction measurements following femtosecond laser excitation in pure bulk chromium. Comparing the evolution of incommensurate charge-density-wave (CDW) and atomic lattice reflections, we show that, a few nanoseconds after laser excitation, the CDW undergoes different structural changes than the atomic lattice. We give evidence for a transient CDW shear strain that breaks the lattice point symmetry. This strain is characteristic of sliding CDWs, as observed in other incommensurate CDW systems, suggesting the laser-induced CDW sliding capability in 3D systems...
October 7, 2016: Physical Review Letters
Anukul Ghimire, Mads Andersen, Lindsay M Burrowes, James Christopher Bouwmeester, Andrew D Grant, Israel Belenkie, Nowell M Fine, Barry A Borlaug, John V Tyberg
Using the reservoir-wave approach (RWA) we previously characterized pulmonary vasculature mechanics in a normal canine model. We found reflected backward-travelling waves that decrease pressure and increase flow in the proximal pulmonary artery (PA). These waves decrease right ventricular (RV) afterload and facilitate RV ejection. With pathological alterations to the pulmonary vasculature, these waves may change and impact RV performance. Our objective in this study was to characterize PA wave reflection and the alterations in RV performance in cardiac patients, using the RWA...
October 20, 2016: Journal of Applied Physiology
Ashley L Greene, Nicholas R Eaton
BACKGROUND: Structural models of psychopathology indicate that common mental disorder comorbidity reflects latent transdiagnostic factors. Multiple studies have replicated transdiagnostic internalizing (mood and anxiety disorders) and externalizing (substance use, antisociality-, and impulsivity-related disorders) factors; other studies support distress and fear sub-factors of internalizing. These factors show a high degree of temporal stability. Recently, a bifactor conceptualization of multivariate comorbidity has emerged, positing the existence of an orthogonal general psychopathology factor that saturates all diagnoses in addition to internalizing/distress/fear and externalizing, although no studies have examined the temporal stability of the factors in this competing model over time among adults...
September 28, 2016: Comprehensive Psychiatry
Ashish Kumar Singh, Bo-Yang Chen, Vincent B C Tan, Tong-Earn Tay, Heow-Pueh Lee
Linear ultrasonics methods based on the principle of reflection, transmission, dissipation of sound waves have been traditionally used to detect delaminations in composite structures. However, when the delamination is in very early stages such that it is almost closed, or closed due to a compressive load, the linear methods may fail to detect such cases of delaminations. Nonlinear acoustics/ultrasonics have shown potential to identify damages in composite structures which are difficult to detect using conventional linear ultrasonic methods...
October 8, 2016: Ultrasonics
Arnoldo Santos, Luca Lucchetta, M Ignacio Monge-Garcia, Joao Batista Borges, Gerardo Tusman, Goran Hedenstierna, Anders Larsson, Fernando Suarez-Sipmann
OBJECTIVE: To test whether positive end-expiratory pressure consistent with an open lung approach improves pulmonary vascular mechanics compared with higher or lower positive end-expiratory pressures in experimental acute respiratory distress syndrome. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: Ten pigs, 35 ± 5.2 kg. INTERVENTIONS: Acute respiratory distress syndrome was induced combining saline lung lavages with injurious mechanical ventilation...
October 19, 2016: Critical Care Medicine
Zhancheng Li, Wenwei Liu, Hua Cheng, Jieying Liu, Shuqi Chen, Jianguo Tian
Optical metasurfaces consisting of single-layer nanostructures have immensely promising applications in wavefront control because they can be used to arbitrarily manipulate wave phase, and polarization. However, anomalous refraction and reflection waves have not yet been simultaneously and asymmetrically generated, and the limited efficiency and bandwidth of pre-existing single-layer metasurfaces hinder their practical applications. Here, a few-layer anisotropic metasurface is presented for simultaneously generating high-efficiency broadband asymmetric anomalous refraction and reflection waves...
October 20, 2016: Scientific Reports
Yu Lun Tai, Hayden Gerhart, Xián Mayo, J Derek Kingsley
Aortic wave reflection characteristics such as the augmentation index (AIx), wasted left ventricular pressure energy (ΔEw ) and aortic haemodynamics, such as aortic systolic blood pressure (ASBP), strongly predict cardiovascular events. The effects of acute resistance exercise (ARE) using free-weight exercises on these characteristics are unknown. Therefore, we sought to determine the effects of acute free-weight resistance exercise on aortic wave reflection characteristics and aortic haemodynamics in resistance-trained individuals...
October 19, 2016: Clinical Physiology and Functional Imaging
Q Mahmood, M Hassan, N A Noor
The structural, magnetic and optical characteristics of Zn1-x TM x S/Se (TM  =  Mn, Fe, Co, Ni and x  =  6.25%) have been investigated through the full-potential linearized augmented plane wave method within the framework of density functional theory. The optimized structures have been used to calculate the ferromagnetic and the antiferromagnetic ground-state energies. The stability of the ferromagnetic phase has been confirmed from the formation and the cohesive energies. The Heisenberg model is used to elucidate the Curie temperature (T c) of these alloys...
October 19, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
M T Camci, P Aydogan, B Ulgut, C Kocabas, S Suzer
We present an X-ray photoelectron spectroscopic (XPS) investigation of potential screening across two gold electrodes fabricated on a porous polymer surface which is impregnated with the ionic liquid (IL) N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide [DEME-TFSI]. The IL provides a sheet of conducting layers to the insulating polymer film, and allows monitoring charging and screening dynamics at the polymer + IL/vacuum interface in a laterally resolved fashion across the electrodes...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Elena Bartoloni, Giacomo Pucci, Francesca Cannarile, Francesca Battista, Alessia Alunno, Marco Giuliani, Giacomo Cafaro, Roberto Gerli, Giuseppe Schillaci
Although microvascular disease is a hallmark of systemic sclerosis (SSc), a higher prevalence of macrovascular disease and a poorer related prognosis have been reported in SSc than in the general population. The simultaneous assessment of prognostically relevant functional properties of larger and smaller arteries, and their effects on central hemodynamics, has never been performed in SSc using the state-of-the-art techniques. Thirty-four women with SSc (aged 61±15 years, disease duration 17±12 years, and blood pressure 123/70±18/11 mm Hg) and 34 healthy women individually matched by age and mean arterial pressure underwent the determination of carotid-femoral (aortic) and carotid-radial (upper limb) pulse wave velocity (a direct measure of arterial stiffness), aortic augmentation (a measure of the contribution of reflected wave to central pulse pressure), and aortobrachial pulse pressure amplification (brachial/aortic pulse pressure) through applanation tonometry (SphygmoCor)...
October 17, 2016: Hypertension
Junichiro Hashimoto
Arterial structure and function change progressively with advancing age. Owing to long-lasting repetitive stretch with intermittent cardiac contraction, elastic fibers in the tunica media of large arteries gradually degenerate and are replaced by collagenous fibers. Such medial degeneration causes elastic arteries to stiffen and dilate. However, the speed of the vascular aging varies considerably among individuals; a discrepancy often exists between the chronological age of an individual and the biological age of his or her arteries...
September 2016: Journal of Hypertension
Trefor Morgan
Central Systolic Blood Pressure is lower than brachial artery blood Pressure due to reflected waves and greater augmentation at the periphery. The relationship is not consistent during life and alters with aging of the blood vessels. Increasing stiffness means that a greater component of the reflected waves returns to the central aorta during systolic contraction causing more amplification and a higher systolic blood pressure. Diastolic blood pressure on the other hand is always higher in the aorta than at the periphery allowing blood flow...
September 2016: Journal of Hypertension
Akio Ishida, Yoshino Kinjo, Yuichiro Toma, Kozen Kinjo, Kunitoshi Iseki, Yusuke Ohya
OBJECTIVE: We reported that ankle-brachial index (ABI) was lowest at <40 years, and increased with age until 60 years and decreased thereafter in a screened cohort of Japanese general population. We hypothesized that this increase in ABI with age occurs owing to increasing arterial stiffness and wave reflection, and therefore, a high normal ABI is associated with target organ damage. DESIGN AND METHOD: We measured ABI and brachial-ankle pulse wave velocity (baPWV) by an automatic oscillometric method...
September 2016: Journal of Hypertension
Audrey Adji, Thomas Weber, Caroline O'Brien, Michael O'Rourke, Alberto Avolio
OBJECTIVE: Previous studies have shown the reciprocal effects of wave reflection on aortic pressure and aortic flow waves. Invasive (Electro-Magnetic (EM)) and non-invasive (Cardiac Magnetic Resonance (CMR)) studies of aortic blood flow have shown characteristic aging changes as reduction in late systolic flow, which corresponds in time to the late systolic boost of aortic pressure. These are not always apparent in Doppler flow tracings. DESIGN AND METHOD: This study aimed to better understand the mechanisms of aortic pressure and flow changes due to early wave reflection and stiffening of arteries...
September 2016: Journal of Hypertension
Peng Yu, Feng Huang, Qiaowei Li, Fan Lin, Pengli Zhu
OBJECTIVE: The objective of this study was to evaluate the association of the central retinal arteriolar equivalent (CRAE) and the retinal vascular fractal dimension, two quantitative parameters that reflect microcirculation, with aortic stiffness. DESIGN AND METHOD: In this cross-sectional study, we identified the cardiovascular risk factors in 2169 subjects using a health questionnaire, physical examinations and laboratory examinations. We evaluated the aortic stiffness using noninvasive brachial-ankle pulse wave velocity (baPWV) and assessed the microcirculatory alterations with CRAE and retinal vascular fractal dimension, which were measured using fundus photography and semiautomatic quantitative software, respectively...
September 2016: Journal of Hypertension
Gary F Mitchell
Aortic stiffness increases markedly with advancing age and is associated with widening of pulse pressure, an increase in pulse wave velocity, earlier return of reflected waves to the proximal aorta and increased risk for target organ damage and adverse outcomes. Various measures of arterial stiffness and wave reflection have been proposed as potential surrogate measures of aortic stiffness. Carotid-femoral pulse wave velocity is a direct measure of aortic wall stiffness that is easily measured with modest requirements for special equipment and training and has been shown to predict events and reclassify cardiovascular disease risk in models that include standard cardiovascular disease risk factors...
September 2016: Journal of Hypertension
Kohji Shirai
BACKGROUND: The cardio-ankle vascular index (CAVI) is a new arterial stiffness index of the arterial tree from the origin of the aorta to the ankle, and was essentially derived from the stiffness parameterβtheory proposed by Hayashi. The conspicuous feature of CAVI is independency from blood pressure at the time of measurement. AIM: The purpose is to clarify the meaning of CAVI as a surrogate marker of arteriosclerosis, and also the role of CAVI in the blood pressure control system...
September 2016: Journal of Hypertension
Amanda B Weber, Dara V Albert, Han Yin, Timothy Held, Anup Patel
INTRODUCTION: Strategies for diagnosing electrical status epilepticus during slow wave sleep (ESES) vary among interpreting neurologists. Our aim was to evaluate if the spike-wave index (SWI) for the first 100 seconds of sleep is reflective of the SWI when compared to a conventional method. METHODS: We reviewed electroencephalograms (EEGs) from 2005-2011 that were considered diagnostic of ESES based on unspecified methods. The SWI for the first non-rapid eye movement (NREM) sleep cycle (long method) was calculated by two neurophysiologists...
June 13, 2016: Journal of Clinical Neurophysiology: Official Publication of the American Electroencephalographic Society
Georgeta D Vaidean, Marta Manczuk, Jared W Magnani
OBJECTIVE: Obesity and hypertension often coexist and represent risk factors for atrial fibrillation. This study hypothesized that their single and joint effects on atrial remodeling would be reflected in the PR interval and P-wave durations on electrocardiogram (ECG). METHODS: This cross-sectional analysis of a community-based study included 11,308 men and women age 45-64. Atrial indices were obtained from digital standard 12-lead resting ECG. Analyses were adjusted for traditional cardiovascular risk factors...
October 18, 2016: Obesity
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