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Heat wave

Cary Presser, Ashot Nazarian, Amit Millo
Thermochemical characteristics were determined for several National Institute of Standards and Technology standard-reference-material petroleum and biodiesel fuels, using a novel laser-heating calorimetry technique. Measurements focused on the sample thermal behavior, specific heat release rate, and total specific heat release. The experimental apparatus consists of a copper sphere-shaped reactor mounted within a chamber, along with laser-beam-steering optical components, gas-supply manifold, and a computer-controlled data-acquisition system...
February 2018: Fuel
Christopher B Skinner, Christopher J Poulsen, Justin S Mankin
Plants influence extreme heat events by regulating land-atmosphere water and energy exchanges. The contribution of plants to changes in future heat extremes will depend on the responses of vegetation growth and physiology to the direct and indirect effects of elevated CO2 . Here we use a suite of earth system models to disentangle the radiative versus vegetation effects of elevated CO2 on heat wave characteristics. Vegetation responses to a quadrupling of CO2 increase summer heat wave occurrence by 20 days or more-30-50% of the radiative response alone-across tropical and mid-to-high latitude forests...
March 15, 2018: Nature Communications
Morgane Dolhen, Masayuki Tanaka, Vincent Couderc, Sébastien Chenu, Gaëlle Delaizir, Tomokatsu Hayakawa, Julie Cornette, François Brisset, Maggy Colas, Philippe Thomas, Jean-René Duclère
We report on the laser emission of the polycrystalline ceramic obtained from the full and congruent crystallization of the parent glass 1Nd3+ :75TeO2 -12.5Bi2 O3 -12.5Nb2 O5 composition. In particular, the current work underlines the importance of carefully controlling the heat treatment in order to solely crystallize the Bi0.8 Nb0.8 Te2.4 O8 cubic phase and consequently avoid the formation of the BiNbTe2 O8 orthorhombic phase that would be detrimental for optical purpose. The structure, microstructure and photoluminescence properties of the resulting transparent tellurite ceramics are characterized...
March 15, 2018: Scientific Reports
Y K Lin, Q H Wu, S Z Wang, A H Wu, L B Su, L H Zheng, J F Chen, Z P Qin, G Q Xie, X D Xu, Q S Song, Q H Yang
The Nd3+ -doped Bi4 Ge3 O12 (BGO) single-crystal fiber (SCF) was successfully grown by the micro-pulling-down method with the resistance heating system. The fluorescence spectrum and transmission spectrum of the Nd:BGO SCF were measured. Excited by a continuous-wave 808-nm laser diode, a fluorescence peak around 1064 nm was observed. At an absorbed pump power of 15.25 W, the Nd:BGO SCF laser delivered a power of 3.37 W with a slope efficiency of 31.2%.
March 15, 2018: Optics Letters
Maxime Markov, Jelena Sjakste, Giuliana Barbarino, Giorgia Fugallo, Lorenzo Paulatto, Michele Lazzeri, Francesco Mauri, Nathalie Vast
Bismuth is one of the rare materials in which second sound has been experimentally observed. Our exact calculations of thermal transport with the Boltzmann equation predict the occurrence of this Poiseuille phonon flow between ≈1.5 and ≈3.5  K, in a sample size of 3.86 and 9.06 mm, consistent with the experimental observations. Hydrodynamic heat flow characteristics are given for any temperature: heat wave propagation length, drift velocity, and Knudsen number. We discuss a gedanken experiment allowing us to assess the presence of a hydrodynamic regime in any bulk material...
February 16, 2018: Physical Review Letters
Joel Cramer, Felix Fuhrmann, Ulrike Ritzmann, Vanessa Gall, Tomohiko Niizeki, Rafael Ramos, Zhiyong Qiu, Dazhi Hou, Takashi Kikkawa, Jairo Sinova, Ulrich Nowak, Eiji Saitoh, Mathias Kläui
Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve...
March 14, 2018: Nature Communications
Devesh Vashishtha, William Sieber, Brittany Hailey, Kristen Guirguis, Alexander Gershunov, Wael K Al-Delaimy
Introduction: The purpose of this study was to determine whether heat waves are associated with increased frequency of clinic visits for ICD-9 codes of illnesses traditionally associated with heat waves. Methods: During 4 years of family medicine clinic data between 2012 and 2016, we identified six heat wave events in San Diego County. For each heat wave event, we selected a control period in the same season that was twice as long. Scheduling a visit on a heat wave day (versus a non-heat wave day) was the primary predictor, and receiving a primary ICD-9 disease code related to heat waves was the outcome...
March 10, 2018: Family Practice
T M Giannaros, K Lagouvardos, V Kotroni, A Matzarakis
This paper presents the development of an operational forecasting service focusing on human-biometeorological conditions. The service is based on the coupling of numerical weather prediction models with an advanced human-biometeorological model. Human thermal perception and stress forecasts are issued on a daily basis for Greece, in both point and gridded format. A user-friendly presentation approach is adopted for communicating the forecasts to the public via the worldwide web. The development of the presented service highlights the feasibility of replacing standard meteorological parameters and/or indices used in operational weather forecasting activities for assessing the thermal environment...
March 12, 2018: International Journal of Biometeorology
Hyunjung Lee, Helmut Mayer
Numerical simulations based on the ENVI-met model were carried out for an E-W street canyon in the city of Stuttgart (Southwest Germany) to analyse the effect of increased albedo of building walls on outdoor human thermal comfort. It was quantified by air temperature (Ta ), mean radiant temperature (Tmrt ) and physiologically equivalent temperature (PET). The simulations were conducted on 4 August 2003 as a heat wave day that represents a typical scenario for future summer weather in Central Europe. The simulation results presented for 13 CET and averaged over the period 10-16 CET are focused on pedestrians on both sidewalks...
March 12, 2018: International Journal of Biometeorology
J Parente, M G Pereira, M Amraoui, E M Fischer
Heat waves (HW) can have devastating social, economic and environmental impacts. Together with long-term drought, they are the main factors contributing to wildfires. Surprisingly, the quantitative and objective analysis leading to the identification and characterization of HW in current and future climate conditions as well as its influence on the occurrence of extreme wildfires (EW) has never been performed for Portugal and are the main objectives of this study. For this reason, we assess HW in recent past and future climate based on a consistent high resolution meteorological database and have compared their occurrence with long and reliable, precise and detailed information about Portuguese fire events...
March 9, 2018: Science of the Total Environment
Akhila Jose, Mrudula Surendran, Sajid Fazal, Bindhu-Paul Prasanth, Deepthy Menon
This work reports the potential of iron quantum clusters (FeQCs) as a hyperthermia agent for cancer, by testing its in-vitro response to shortwave (MHz range), radiofrequency (RF) waves non-invasively. Stable, fluorescent FeQCs of size ∼1 nm prepared by facile aqueous chemistry from endogenous protein haemoglobin were found to give a high thermal response, with a ΔT ∼50 °C at concentrationsas low as165 μg/mL. The as-prepared nanoclusters purified by lyophilization as well as dialysis showed a concentration, power and time-dependent RF response, with the lyophilized FeQCs exhibiting pronounced heating effects...
February 27, 2018: Colloids and Surfaces. B, Biointerfaces
Martin Loynaz Prieto, Kamyar Firouzi, Butrus T Khuri-Yakub, Merritt Maduke
Ultrasound (US) can modulate the electrical activity of the excitable tissues, but the mechanisms underlying this effect are not understood at the molecular level or in terms of the physical modality through which US exerts its effects. Here, we report an experimental system that allows for stable patch-clamp recording in the presence of US at 43 MHz, a frequency known to stimulate neural activity. We describe the effects of US on two ion channels proposed to be involved in the response of excitable cells to US: the mechanosensitive Piezo1 channel and the voltage-gated sodium channel NaV 1...
March 7, 2018: Ultrasound in Medicine & Biology
Yaser Khorrami, Vahid Ahmadi, Mohammad Razaghi, Narottam Das
In this paper, we numerically analyze nonlinear asymmetric switching using a semiconductor optical amplifier (SOA) phase-shifter-based Mach-Zehnder interferometer (MZI), for the first time, to the best of our knowledge. The self-phase modulation (SPM) effect and nonlinear phase shift in each MZI arm are investigated for different input pulse intensities and linear gains in both picosecond and femtosecond regimes. The input light signal is split unequally over the two arms, where SOAs are placed and act as nonlinear phase shifters in each arm...
March 1, 2018: Applied Optics
K W Oleson, G B Anderson, B Jones, S A McGinnis, B Sanderson
Previous studies examining future changes in heat/cold waves using climate model ensembles have been limited to grid cell-average quantities. Here, we make use of an urban parameterization in the Community Earth System Model (CESM) that represents the urban heat island effect, which can exacerbate extreme heat but may ameliorate extreme cold in urban relative to rural areas. Heat/cold wave characteristics are derived for U.S. regions from a bias-corrected CESM 30-member ensemble for climate outcomes driven by the RCP8...
February 2018: Climatic Change
Yang Yang, Leping Zhou, Xiao-Ze Du, Yongping Yang
The microscopic region near the triple line plays an important role in the heat and mass transfer of droplets, while the mechanisms of evaporation and internal flow remain unclear. This paper describes an experimental study of fluid flow and thin-film evolution near the triple line in sessile droplets of self-rewetting fluids, aqueous solutions of alcohols with number of carbon atoms varies from 1 to 7, to analyze the influence of various factors on the mesoscale flows. The mechanism of internal flow for self-rewetting fluid droplets was different from that of conventional fluids, and hence a novel expression of in-plane average velocity was fitted for them...
March 7, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
David A Nelson, Silas J Leavesley, Carmen D Zirlott, Xi-Ming Yang, James M Downey
Implementation of clinical guidelines for diagnosing Peripheral Artery Disease (PAD) will demand screening many millions of patients who are considered at-risk. This will demand faster, easier screening technologies to identify patients with compromised blood flow to the extremities. The feasibility of using surface temperature response to Ka band (26.5 - 40 GHz) near-field irradiation to assess skin blood flow was explored using an animal model. Ears of domestic rabbits were subjected to low power continuous wave radio frequency heating from an open-ended waveguide (WR-28) at f=35 GHz...
March 7, 2018: Physiological Measurement
Andreas Lamkowski, Matthias Kreitlow, Jörg Radunz, Martin Willenbockel, Frank Sabath, Winfried Schuhn, Marcus Stiemer, Lars Ole Fichte, Michael Dudzinski, Sebastian Böhmelt, Reinhard Ullmann, Matthäus Majewski, Valeria Franchini, Stefan Ede, Alexis Rump, Matthias Port, Michael Abend
Radiofrequency electromagnetic fields (RF-EMF) are a basic requirement of modern wireless communication technology. Statutory thresholds of RF-EMF are established to limit relevant additional heat supply in human tissue. Nevertheless, to date, questions concerning nonthermal biological effects have yet to be fully addressed. New versions of microarrays (8 × 60K v2) provide a higher resolution of whole genome gene expression to display adaptive processes in cells after irradiation. In this ex vivo/ in vitro study, we irradiated peripheral blood cells from five donors with a continuous wave of 900 MHz RF-EMF for 0, 30, 60 and 90 min...
March 6, 2018: Radiation Research
Federico Cilento, Giulia Manzoni, Andrea Sterzi, Simone Peli, Andrea Ronchi, Alberto Crepaldi, Fabio Boschini, Cephise Cacho, Richard Chapman, Emma Springate, Hiroshi Eisaki, Martin Greven, Mona Berciu, Alexander F Kemper, Andrea Damascelli, Massimo Capone, Claudio Giannetti, Fulvio Parmigiani
Many puzzling properties of high-critical temperature ( T c ) superconducting (HTSC) copper oxides have deep roots in the nature of the antinodal quasiparticles, the elementary excitations with wave vector parallel to the Cu-O bonds. These electronic states are most affected by the onset of antiferromagnetic correlations and charge instabilities, and they host the maximum of the anisotropic superconducting gap and pseudogap. We use time-resolved extreme-ultraviolet photoemission with proper photon energy (18 eV) and time resolution (50 fs) to disclose the ultrafast dynamics of the antinodal states in a prototypical HTSC cuprate...
February 2018: Science Advances
Liang-Juan Chang, Yen-Fu Liu, Ming-Yi Kao, Li-Zai Tsai, Jun-Zhi Liang, Shang-Fan Lee
Spin waves (SW) are low energy excitations of magnetization in magnetic materials. In the promising field of magnonics, fundamental SW modes, magnons, are accessible in magnetic nanostructure waveguides and carry information. The SW propagates in both metals and insulators via magnetization dynamics. Energy dissipation through damping can be low compared to the Joule heating in conventional circuits. We performed simulations in a quasi-one-dimensional ferromagnetic strip and found that the transmission of the propagating SW across the domain wall (DW) depends strongly on the tilt angle of the magnetization at low frequencies...
March 2, 2018: Scientific Reports
Qiong Zhang, Xingzhi Han, Xin Hao, Liang Ma, Shuran Li, Yang Wang, Weiguo Du
Understanding how organisms respond to warming contributes important information to the conservation of biodiversity that is threatened by climate warming. Here, we conducted experiments on a desert agama (Phrynocephalus przewalskii) to test the hypothesis that climate warming (an increase in both mean temperature and heat waves) would induce oxidative stress, shortening telomere length, and thereby decreasing survival. Our results demonstrated that one week of exposure to a simulated heat wave significantly shortened telomere length, and decreased the overwinter survival of lizards, but mean temperature increase did not affect the survival of lizards...
February 2018: Journal of Thermal Biology
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