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Sample records for thermal limits depend

  1. Phenotypic variance, plasticity and heritability estimates of critical thermal limits depend on methodological context

    DEFF Research Database (Denmark)

    Chown, Steven L.; Jumbam, Keafon R.; Sørensen, Jesper Givskov

    2009-01-01

    1.  Biologists have long been concerned with measuring thermal performance curves and limits because of their significance to fitness. Basic experimental design may have a marked effect on the outcome of such measurements, and this is true especially of the experimental rates of temperature chang...

  2. Estimation of thermal fracture limits in quasi-continuous-wave end-pumped lasers through a time-dependent analytical model

    NARCIS (Netherlands)

    Bernhardi, Edward; Martijn de Sterke, C.; Forbes, A.; Bollig, C.; Esser, M.J.D.

    2008-01-01

    A time–dependent analytical thermal model of the temperature and the corresponding induced thermal stresses on the pump face of quasi–continuous wave (qcw) end-pumped laser rods is derived. We apply the model to qcw diode–end–pumped rods and show the maximum peak pump power that can be utilized

  3. Thermal activation model of endurance limit

    Science.gov (United States)

    Lü, Baotong; Zheng, Xiulin

    1992-09-01

    A thermal activation model of the endurance limit is proposed in the present study. It can quantitatively explain the effects of temperature and frequency on the endurance limit of metals at or below room temperature. Theoretical analysis indicates that the endurance limit, σac, which is considered as a parameter characterizing the resistance of metals to cyclic microplastic deformation, has the same thermally activated nature as the plastic flow stress has and it can be resolved into two independent components: the long-range internal stress (the athermal component), μ(ɛapc), and the short-range effective stress (the thermal component), σa *( T, ɛp). The former is considered as a material constant insensitive to temperature and strain rate (or frequency). The latter, the temperature- and strain rate-dependent part of the endurance limit, is approximately identical with the effective stress component of plastic flow stress (or cyclic yielding stress). In light of the thermal activation model, the temperature and strain-rate dependence of monotonic and cyclic flow stresses in a low alloy steel (16Mn) and a precipitation-hardening aluminum alloy (LY12CZ) were experimentally investigated. The results indicate that the effective stress components of monotonic and cyclic flow stresses are identical, if the temperature and strain rate are held unchanged, and that both of them are approximately independent of the magnitude of plastic strain. On the basis of the thermal activation model, an expression predicting the endurance limit below room temperature is offered. The predicted values of the endurance limit agree with the test data of steels and aluminum alloys available in literature.

  4. Temperature Dependence of Cell Division Timing Accounts for a Shift in the Thermal Limits of C. elegans and C. briggsae

    Directory of Open Access Journals (Sweden)

    Maria L. Begasse

    2015-02-01

    Full Text Available Cold-blooded animals, which cannot directly control their body temperatures, have adapted to function within specific temperature ranges that vary between species. However, little is known about what sets the limits of the viable temperature range. Here we show that the speed of the first cell division in C. elegans N2 varies with temperature according to the Arrhenius equation. However, it does so only within certain limits. Outside these limits we observe alterations in the cell cycle. Interestingly, these temperature limits also correspond to the animal’s fertile range. In C. briggsae AF16, isolated from a warmer climatic region, both the fertile range and the temperature range over which the speed of cell division follows the Arrhenius equation, are shifted toward higher temperatures. Our findings suggest that the viable range of an organism can be adapted in part to a different thermal range by adjusting the temperature tolerance of cell division.

  5. Proposed Thermal Limits for Divers

    Science.gov (United States)

    1984-07-01

    recommended minimum inspired gas temperature as a function of depth, or pressure of the respired gas. Braithwaite, 1972. 4 m ersion ( diuresis and...levels of indicators of generalized stress, such as corticoids and catecholamines in blood and a greater urine content of such substances or their...stress that can be limiting io. underwater operations. it may be produced by diuresis , by a lack of ingest I water, or by a loss of water through

  6. TEMPERATURE DEPENDENCE OF THE THERMAL ...

    African Journals Online (AJOL)

    Thermal conductivity values, in the temperature range 300 – 1200 K, have been measured in air and at atmospheric pressure for a Kenyan kaolinite refractory with 0% - 50% grog proportions. The experimental thermal conductivity values were then compared with those calculated using the Zumbrunnen et al [1] and the ...

  7. Length-dependent thermal transport and ballistic thermal conduction

    Directory of Open Access Journals (Sweden)

    Bor-Woei Huang

    2015-05-01

    Full Text Available Probing length-dependent thermal conductivity of a given material has been considered as an important experimental method to determine the length of ballistic thermal conduction, or equivalently, the averaged phonon mean free path (l. However, many previous thermal transport measurements have focused on varying the lateral dimensions of samples, rendering the experimental interpretation indirect. Moreover, deducing l is model-dependent in many optical measurement techniques. In addition, finite contact thermal resistances and variations of sample qualities are very likely to obscure the effect in practice, leading to an overestimation of l. We point out that directly investigating one-dimensional length-dependent (normalized thermal resistance is a better experimental method to determine l. In this regard, we find that no clear experimental data strongly support ballistic thermal conduction of Si or Ge at room temperature. On the other hand, data of both homogeneously-alloyed SiGe nanowires and heterogeneously-interfaced Si-Ge core-shell nanowires provide undisputed evidence for ballistic thermal conduction over several micrometers at room temperature.

  8. Determination of the Thermal Noise Limit of Graphene Biotransistors.

    Science.gov (United States)

    Crosser, Michael S; Brown, Morgan A; McEuen, Paul L; Minot, Ethan D

    2015-08-12

    To determine the thermal noise limit of graphene biotransistors, we have measured the complex impedance between the basal plane of single-layer graphene and an aqueous electrolyte. The impedance is dominated by an imaginary component but has a finite real component. Invoking the fluctuation-dissipation theorem, we determine the power spectral density of thermally driven voltage fluctuations at the graphene/electrolyte interface. The fluctuations have 1/f(p) dependence, with p = 0.75-0.85, and the magnitude of fluctuations scales inversely with area. Our results explain noise spectra previously measured in liquid-gated suspended graphene devices and provide realistic targets for future device performance.

  9. Anomalous size dependence of the thermal conductivity of graphene ribbons.

    Science.gov (United States)

    Nika, Denis L; Askerov, Artur S; Balandin, Alexander A

    2012-06-13

    We investigated the thermal conductivity K of graphene ribbons and graphite slabs as the function of their lateral dimensions. Our theoretical model considered the anharmonic three-phonon processes to the second-order and included the angle-dependent phonon scattering from the ribbon edges. It was found that the long mean free path of the long-wavelength acoustic phonons in graphene can lead to an unusual nonmonotonic dependence of the thermal conductivity on the length L of a ribbon. The effect is pronounced for the ribbons with the smooth edges (specularity parameter p > 0.5). Our results also suggest that, contrary to what was previously thought, the bulk-like three-dimensional phonons in graphite make a rather substantial contribution to its in-plane thermal conductivity. The Umklapp-limited thermal conductivity of graphite slabs scales, for L below ∼30 μm, as log(L), while for larger L, the thermal conductivity approaches a finite value following the dependence K(0) - A × L(-1/2), where K(0) and A are parameters independent of the length. Our theoretical results clarify the scaling of the phonon thermal conductivity with the lateral sizes in graphene and graphite. The revealed anomalous dependence K(L) for the micrometer-size graphene ribbons can account for some of the discrepancy in reported experimental data for graphene.

  10. Time-Dependent Thermal Transport Theory.

    Science.gov (United States)

    Biele, Robert; D'Agosta, Roberto; Rubio, Angel

    2015-07-31

    Understanding thermal transport in nanoscale systems presents important challenges to both theory and experiment. In particular, the concept of local temperature at the nanoscale appears difficult to justify. Here, we propose a theoretical approach where we replace the temperature gradient with controllable external blackbody radiations. The theory recovers known physical results, for example, the linear relation between the thermal current and the temperature difference of two blackbodies. Furthermore, our theory is not limited to the linear regime and goes beyond accounting for nonlinear effects and transient phenomena. Since the present theory is general and can be adapted to describe both electron and phonon dynamics, it provides a first step toward a unified formalism for investigating thermal and electronic transport.

  11. Frequency dependent thermal expansion in binary viscoelasticcomposites

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, James G.

    2007-12-01

    The effective thermal expansion coefficient beta* of abinary viscoelastic composite is shown to be frequency dependent even ifthe thermal expansion coefficients beta A and beta B of both constituentsare themselves frequency independent. Exact calculations for binaryviscoelastic systems show that beta* is related to constituent valuesbeta A, beta B, volume fractions, and bulk moduli KA, KB, as well as tothe overall bulk modulus K* of the composite system. Then, beta* isdetermined for isotropic systems by first bounding (or measuring) K* andtherefore beta*. For anisotropic systems with hexagonal symmetry, theprincipal values of the thermal expansion beta*perp and beta*para can bedetermined exactly when the constituents form a layered system. In allthe examples studied, it is shown explicitly that the eigenvectors of thethermoviscoelastic system possess non-negative dissipation -- despite thecomplicated analytical behavior of the frequency dependent thermalexpansivities themselves. Methods presented have a variety ofapplications from fluid-fluid mixtures to fluid-solid suspensions, andfrom fluid-saturated porous media to viscoelastic solid-solidcomposites.

  12. Thermal Management for Dependable On-Chip Systems

    OpenAIRE

    Ebi, Thomas

    2014-01-01

    This thesis addresses the dependability issues in on-chip systems from a thermal perspective. This includes an explanation and analysis of models to show the relationship between dependability and tempature. Additionally, multiple novel methods for on-chip thermal management are introduced aiming to optimize thermal properties. Analysis of the methods is done through simulation and through infrared thermal camera measurements.

  13. Influence of Thermal Anisotropy on Equilibrium Stellarator Beta Limits

    Science.gov (United States)

    Bechtel, T. A.; Hegna, C. C.; Sovinec, C. R.

    2017-10-01

    The effect of anisotropic heat conduction on the upper beta limit of stellarator plasmas is studied using the nonlinear, extended MHD code NIMROD. The configuration under investigation is an l=2, M=10 torsatron with vacuum rotational transform near unity. Finite-beta plasmas are created using a volumetric heating source and temperature dependent resistivity; modeled with 22 stellarator symmetric (integer multiples of M) toroidal modes. Extended MHD simulations are then performed to generate steady state solutions that represent 3D equilibria. With increased heating, Shafranov shifts occur, and the associated break up of edge magnetic surfaces limits the achievable beta. Due to the presence of finite parallel heat conduction, pressure profiles can exist in regions of magnetic stochasticity. Here, we present results of independently varying the parallel and perpendicular thermal anisotropy. In particular, simulations show that the attained stored energy is a function of the magnitude of parallel and perpendicular thermal conduction for a given heat source, indicating that equilibrium beta limits are sensitive to anisotropic transport properties. Preliminary studies of MHD stability with non-stellarator symmetric modes, near the highest achievable beta, are also presented. Research supported by US DOE under Grant No. DE-FG02-99ER54546.

  14. Reconstruction of recent 10Ma thermal structure seaward of updip limit of Nankai seismogenic zone off Kumano inferred from IODP NanTroSEIZE geothermal data and time-dependent numerical model

    Science.gov (United States)

    Kinoshita, Masataka; Araki, Eiichiro; Kimura, Toshinori; Kopf, Achim; Saffer, Demian; Toczko, Sean

    2017-04-01

    Understanding the slip behavior of the seismogenic faults in subduction zones requires accurate estimates on the present & past thermal structures. Some geochemical processes that affect the effective fault strength (such as clay mineral dehydration) require a knowledge on the thermal history of sediment particles since its deposition. To depict the thermal history, we need to know the tectonics and thermal regime of the Philippine Sea plate (PHS), which may have stopped subduction until 6MaBP, and restarted afterwards. Our purpose here is to test if such subduction tectonics can affect the 'present' thermal regime, which can be constrained by the heat flow measured at the seafloor or by the borehole measurements. During the IODP NanTroSEIZE expeditions, we deployed 2 borehole observatories containing 5 thermistors. In 2012, the first observatory was deployed at Site C0002 above the updip limit of locked portion of megathrust, and the temperature and heat flow at 900 m below seafloor is determined as 37.8 degC and 57 mW/m2, respectively (Sugihara et al., 2014). In 2016, we deployed the second observatory at Sites C0010 across the shallow portion of megasplay fault zone. Thermistors are located between 400 mbsf (crossing the fault zone) and 562.72 mbsf, and the temperature at 562.7 mbsf is 26.7 degC. With core thermal conductivity data, average heat flow is determined as 60 mW/m2. It is slightly higher than the heat flow at the nearby Site C0004 (54 mW/m2; Harris et al., 2011). This high heat flow may be attributed wither to pore fluid flow or transient phenomena (e.g., burial due to thrust faulting). Using these heat flow data, a thermal structure model around the updip zone of Nankai seismogenic zone is constructed for 2 end-member models; subduction of 12Ma-old Shikoku Basin (SB) started at 6MaBP, vs. subduction of 5Ma-old SB continued since 13MaBP. To account for the high heat flow seaward of trough axis, we followed the effective thermal conductivity model

  15. Network and guest dependent thermal stability and thermal ...

    Indian Academy of Sciences (India)

    after the guest loss.32,64–66 Previously, lower thermal expansion due to low guest content have been shown only in the case of metal-organic frameworks. Thermal vibration of the guest molecules along the open channel axis does not cause expansion in the host network. This could be another reason for lower thermal ...

  16. SOME MOISTURE DEPENDENT THERMAL PROPERTIES AND ...

    African Journals Online (AJOL)

    The thermal heat conductivity, specific heat capacity, thermal heat diffusivity and bulk density of Prosopis africana seeds were determined as a function of moisture content. Specific heat capacity was measured by the method of mixture while the thermal heat conductivity was measured by the guarded hot plate method.

  17. Temperature-dependent thermal properties of spark plasma sintered alumina

    Directory of Open Access Journals (Sweden)

    Saheb Nouari

    2017-01-01

    Full Text Available In this work, we report temperature-dependent thermal properties of alumina powder and bulk alumina consolidated by spark plasma sintering method. The properties were measured between room temperature and 250ºC using a thermal constants analyzer. Alumina powder had very low thermal properties due to the presence of large pores and absence of bonding between its particles. Fully dense alumina with a relative density of 99.6 % was obtained at a sintering temperature of 1400°C and a holding time of 10 min. Thermal properties were found to mainly dependent on density. Thermal conductivity, thermal diffusivity, and specific heat of the fully dense alumina were 34.44 W/mK, 7.62 mm2s-1, and 1.22 J/gK, respectively, at room temperature. Thermal conductivity and thermal diffusivity decreased while specific heat increased with the increase in temperature from room temperature to 250ºC.

  18. Thermal Imagery of Groundwater Seeps: Possibilities and Limitations.

    Science.gov (United States)

    Mundy, Erin; Gleeson, Tom; Roberts, Mark; Baraer, Michel; McKenzie, Jeffrey M

    2017-03-01

    Quantifying groundwater flow at seepage faces is crucial because seepage faces influence the hydroecology and water budgets of watersheds, lakes, rivers and oceans, and because measuring groundwater fluxes directly in aquifers is extremely difficult. Seepage faces provide a direct and measurable groundwater flux but there is no existing method to quantitatively image groundwater processes at this boundary. Our objective is to determine the possibilities and limitations of thermal imagery in quantifying groundwater discharge from discrete seeps. We developed a conceptual model of temperature below discrete seeps, observed 20 seeps spectacularly exposed in three dimensions at an unused limestone quarry and conducted field experiments to examine the role of diurnal changes and rock face heterogeneity on thermal imagery. The conceptual model suggests that convective air-water heat exchange driven by temperature differences is the dominant heat transfer mechanism. Thermal imagery is effective at locating and characterizing the flux of groundwater seeps. Areas of active groundwater flow and ice growth can be identified from thermal images in the winter, and seepage rates can be differentiated in the summer. However, the application of thermal imagery is limited by diverse factors including technical issues of image acquisition, diurnal changes in radiation and temperature, and rock face heterogeneity. Groundwater discharge rates could not be directly quantified from thermal imagery using our observations but our conceptual model and experiments suggest that thermal imagery could quantify groundwater discharge when there are large temperature differences, simple cliff faces, non-freezing conditions, and no solar radiation. © 2016, National Ground Water Association.

  19. Temperature dependence of thermal conductivity of vanadium ...

    Indian Academy of Sciences (India)

    Unknown

    . Cryogenic Engineering .... Thermal conductivity of vanadium substituted BPSCCO system. 441 trical resistivity as well as the small decrease ..... G, Marre D, Putti M and Siri A S 1997 Physica C273 314. Chawlek J M, Uher C, Whitaker J F and ...

  20. Time-dependent thermal effects in GRB afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Postnov, K.A.; Blinnikov, S.I.; Kosenko, D.I.; Sorokina, E.I

    2004-06-01

    Time-dependent thermal effects should accompany standard non-thermal afterglows of GRB when {gamma}-rays pass through inhomogeneous surroundings of the GRB site. Thermal relaxation of an optically thin plasma is calculated using time-dependent collisional ionization of the plasma ion species. X-ray emission lines are similar to those found in the fading X-ray afterglow of GRB 011211. Thermal relaxation of clouds or shells around the GRB site could also contribute to the varying late optical GRB afterglows, such as in GRB 021004 and GRB 030329.

  1. Pressure dependence of thermal transport properties.

    Science.gov (United States)

    Hofmeister, Anne M

    2007-05-29

    Pressure (P) derivatives of thermal conductivity (k) and thermal diffusivity (D) are important to geophysics but are difficult to measure accurately because minerals, being hard and partially transparent, likely incur systematic errors through thermal losses at interfaces and spurious radiative transfer. To evaluate accuracy, repeat experiments for olivine [(Mg(0.9)Fe(0.1))(2)SiO4], quartz (SiO2), and NaCl are examined in detail: these and other data on electrical insulators are compared with theory. At ambient conditions, D is underestimated in proportion to the number of contacts. As temperature (T) increases, spurious radiative transfer more than offsets contact loss. Compression of pore space and contact losses affect pressure derivatives, but these seem independent of T. Accurate (+/-2%) values of D(T) at 1 atm are obtained with the contact-free, laser-flash method. Other optical techniques do not pinpoint D but provide useful pressure derivatives. Published data on (partial differential)(lnk)/(partial differential)P at ambient conditions agree roughly with all available models, the simplest of which predicts (partial differential)(lnk)/(partial differential)P approximately (partial differential)(lnK(T))/(partial differential)P, where K(T) is the bulk modulus. However, derivatives verified by multiple measurements are reproduced accurately only by the damped harmonic oscillator model. An improved database is needed to refine this model and to confidently extrapolate these difficult measurements to geophysically relevant conditions.

  2. A temperature dependent slip factor based thermal model for friction ...

    Indian Academy of Sciences (India)

    This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power required, the ...

  3. A temperature dependent slip factor based thermal model for friction ...

    Indian Academy of Sciences (India)

    Abstract. This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power ...

  4. Thermal state of the general time-dependent harmonic oscillator

    Indian Academy of Sciences (India)

    the thermal state. In Ü2, we investigate quantum mechanical solution of the general time-dependent har- monic oscillator. The thermal state of the system is discussed in Ü3 on the basis of. Liouville–von Neumann approach. InÜ4, we will apply our theory for a special case which is the forced Caldirola–Kanai oscillator.

  5. Time-dependent analytical thermal model to investigate thermally induced stresses in quasi-CW-pumped laser rods

    CSIR Research Space (South Africa)

    Bernhardi, EH

    2008-01-01

    Full Text Available One of the main problems that limit the power scaling of diode-end-pumped solid-state lasers is the generation of heat inside the laser gain medium which can ultimately cause fracture. In this paper a time-dependent analytical thermal model...

  6. Thermal infrared imaging in psychophysiology: potentialities and limits.

    Science.gov (United States)

    Ioannou, Stephanos; Gallese, Vittorio; Merla, Arcangelo

    2014-10-01

    Functional infrared thermal imaging (fITI) is considered an upcoming, promising methodology in the emotional arena. Driven by sympathetic nerves, observations of affective nature derive from muscular activity subcutaneous blood flow as well as perspiration patterns in specific body parts. A review of 23 experimental procedures that employed fITI for investigations of affective nature is provided, along with the adopted experimental protocol and the thermal changes that took place on selected regions of interest in human and nonhuman subjects. Discussion is provided regarding the selection of an appropriate baseline, the autonomic nature of the thermal print, the experimental setup, methodological issues, limitations, and considerations, as well as future directions. © 2014 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research.

  7. Thermal Cooling Limits of Sbotaged Spent Fuel Pools

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Thomas G. Hughes; Dr. Thomas F. Lin

    2010-09-10

    To develop the understanding and predictive measures of the post “loss of water inventory” hazardous conditions as a result of the natural and/or terrorist acts to the spent fuel pool of a nuclear plant. This includes the thermal cooling limits to the spent fuel assembly (before the onset of the zircaloy ignition and combustion), and the ignition, combustion, and the subsequent propagation of zircaloy fire from one fuel assembly to others

  8. Compact model of power MOSFET with temperature dependent Cauer RC network for more accurate thermal simulations

    Science.gov (United States)

    Marek, Juraj; Chvála, Aleš; Donoval, Daniel; Príbytný, Patrik; Molnár, Marián; Mikolášek, Miroslav

    2014-04-01

    A new, more accurate SPICE-like model of a power MOSFET containing a temperature dependent thermal network is described. The designed electro-thermal MOSFET model consists of several parts which represent different transistor behavior under different conditions such as reverse bias, avalanche breakdown and others. The designed model is able to simulate destruction of the device as thermal runaway and/or overcurrent destruction during the switching process of a wide variety of inductive loads. Modified thermal equivalent circuit diagrams were designed taking into account temperature dependence of thermal resistivity. The potential and limitations of the new models are presented and analyzed. The new model is compared with the standard and empirical models and brings a higher accuracy for rapid heating pulses. An unclamped inductive switching (UIS) test as a stressful condition was used to verify the proper behavior of the designed MOSFET model.

  9. Dependence of Glass Mechanical Properties on Thermal and Pressure History

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauchy, Mathieu

    Predicting the properties of new glasses prior to manufacturing is a topic attracting great industrial and scientific interest. Mechanical properties are currently of particular interest given the increasing demand for stronger, thinner, and more flexible glasses in recent years. However, as a non......-equilibrium material, the structure and properties of glass depend not only on its composition, but also on its thermal and pressure histories. Here we review our recent findings regarding the thermal and pressure history dependence of indentation-derived mechanical properties of oxide glasses....

  10. GAYA KOGNITIF FIELD DEPENDENT TERHADAP PEMAHAMAN KONSEP LIMIT MAHASISWA

    Directory of Open Access Journals (Sweden)

    Nurafni Nurafni

    2016-11-01

    Full Text Available Penelitian ini merupakan penelitian deskriptif dengan pendekatan kualitatif yang bertujuan untuk mendeskripsikan profil pemahaman konsep limit mahasiswa berdasarkan gaya kognitif field dependent. Subjek penelitian ini adalah mahasiswa semester II UHAMKA Jakarta. Penelitian dimulai dengan menentukan subjek penelitian menggunakan instrumen GEFT serta kesediaan mahasiswa dan hasil konsultasi dengan dosen bidang studi, Kemudian dilanjutkan dengan pemberian tes pemahaman konsep limit fungsi (TPKLF dan wawancara. Pengecekan keabsahan data menggunakan triangulasi waktu. Hasil penelitian menunjukan bahwa Pemahaman mahasiswa dengan gaya kognitif field dependent terhadap konsep limit ketika menyatakan makna limit yang diberikan menggunakan bahasanya sendiri hanya terpaku pada notasi limit yang diberikan. Subjek tidak dapat dapat mengkaitkan antar apa yang diketahui dalam soal dengan informasi lain yang diberikan. Ketika menggunakan konsep limit untuk menyelesaikan masalah yang diberikan, subjek tidak memenuhi indikator ini dikarenakan subjek menggunakan cara prosedural bukan menggunakan konsep limit yang diketahuinya untuk menyelesaikan masalah yang diberikan. Ketika menggunakan syarat perlu atau syarat cukup untuk menentukan ada atau tidaknya stuatu limit subjek mampu menggunakan syarat perlu untuk menentukan suatu limit jika limit tersebut tidak memiliki syarat yang berbeda. Jika limit yang diberikan memiliki syarat yang berbeda, subjek tersebut tidak dapat menggunakan syarat perlu untuk menentukan ada atau tidaknya suatu limit.

  11. On q dependence of thermal transport in tokamaks

    Science.gov (United States)

    Hirose, A.; Livingstone, S.; Singh, A. K.

    2005-12-01

    Analysis based on a gyro-kinetic ballooning stability code predicts that both the ion and electron thermal diffusivities, due to the ion temperature gradient (ITG) and electron temperature gradient (ETG) modes, respectively, increase with the safety factor q almost linearly. In the case of ITG driven ion thermal diffusivity, the q dependence originates from the coupling to the ion acoustic mode, and in the case of the electron thermal diffusivity due to the ETG mode, it emerges from the coupling to the skin size drift mode. In the ETG mode, charge neutrality does not hold for typical tokamak discharges, and mixing length estimates yield a thermal diffusivity large enough to be relevant to experiments.

  12. Temperature dependence of thermal conductivity of biological tissues.

    Science.gov (United States)

    Bhattacharya, A; Mahajan, R L

    2003-08-01

    In this paper, we present our experimental results on the determination of the thermal conductivity of biological tissues using a transient technique based on the principles of the cylindrical hot-wire method. A novel, 1.45 mm diameter, 50 mm long hot-wire probe was deployed. Initial measurements were made on sponge, gelatin and Styrofoam insulation to test the accuracy of the probe. Subsequent experiments conducted on sheep collagen in the range of 25 degrees C thermal conductivity to be a linear function of temperature. Further, these changes in the thermal conductivity were found to be reversible. However, when the tissue was heated beyond 55 degrees C, irreversible changes in thermal conductivity were observed. Similar experiments were also conducted for determining the thermal conductivity of cow liver. In this case, the irreversible effects were found to set in much later at around 90 degrees C. Below this temperature, in the range of 25 degrees C thermal conductivity, as for sheep collagen, varied linearly with temperature. In the second part of our study, in vivo measurements were taken on the different organs of a living pig. Comparison with reported values for dead tissues shows the thermal conductivities of living organs to be higher, indicating thereby the dominant role played by blood perfusion in enhancing the net heat transfer in living tissues. The degree of enhancement is different in different organs and shows a direct dependence on the blood flow rate.

  13. HVI Ballistic Limit Charaterization of Fused Silica Thermal Pane

    Science.gov (United States)

    Bohl, William E.; Miller, Joshua E.; Christiansen, Eric L.; Deighton, Kevin.; Davis, Bruce

    2015-01-01

    The Orion spacecraft's windows are exposed to the micrometeroid and orbital debris (MMOD) space environments while in space as well as the Earth entry environment at the mission's conclusion. The need for a low-mass spacecraft window design drives the need to reduce conservatism when assessing the design for loss of crew due to MMOD impact and subsequent Earth entry. Therefore, work is underway at NASA and Lockheed Martin to improve characterization of the complete penetration ballistic limit of an outer fused silica thermal pane. Hypervelocity impact tests of the window configuration at up to 10 km/s and hydrocode modeling have been performed with a variety of projectile materials to enable refinement of the fused silica ballistic limit equation.

  14. Effects of nanoscale size dependent parameters on lattice thermal ...

    Indian Academy of Sciences (India)

    Throughout the method of trial and error, using the MATHCAD. 12 program, the values of P,Nimp and γ were adjusted such that the best fit for calculated lattice thermal conductivity to the experimental curves were obtained as shown in figure 3. The diameter dependence of the fitting parameters Nimp,P and γ (L, T ) and γ ...

  15. Symbiont Dependent Thermal Bleaching Susceptiblity in Two Reef ...

    African Journals Online (AJOL)

    Symbiont Dependent Thermal Bleaching Susceptiblity in Two Reef-building Corals, Stylophora pistillata and Platygyra ryukyuensis . ... pistillata) and the other resistant (Platygyra ryukyuensis) to bleaching, were exposed to a sudden elevated temperature (33.5oC) under dim light (5 μmol quanta m-2 s-1) for 10 to 720 min in ...

  16. Thermal state of the general time-dependent harmonic oscillator

    Indian Academy of Sciences (India)

    Taking advantage of dynamical invariant operator, we derived quantum mechanical solution of general time-dependent harmonic oscillator. The uncertainty relation of the system is always larger than ħ=2 not only in number but also in the thermal state as expected. We used the diagonal elements of density operator ...

  17. Symbiont Dependent Thermal Bleaching Susceptiblity in Two Reef ...

    African Journals Online (AJOL)

    user1

    Symbiont Dependent Thermal Bleaching Susceptiblity in Two Reef-building Corals, Stylophora pistillata and. Platygyra ryukyuensis ... 2001), on the Great Barrier Reef, Australia (Marshall &. Baird, 2000; Baird .... CHAOS solution (4M guanidine thiocyanate, 0.5% salcosyl, 2.5 mM Tris (pH, 8.0), 0.1 M 2- mercaptoethanol and ...

  18. On the effect of temperature dependent thermal conductivity on ...

    African Journals Online (AJOL)

    We consider the effect of temperature dependent thermal conductivity on temperature rise in biologic tissues during microwave heating. The method of asymptotic expansion is used for finding solution. An appropriate matching procedure was used in our method. Our result reveals the possibility of multiple solutions and it ...

  19. Interspecific variation for thermal dependence of glutathione reductase in sainfoin.

    Science.gov (United States)

    Kidambi, S P; Mahan, J R; Matches, A G

    1990-05-01

    Understanding the biochemical and physiological consequences of species variation would expedite improvement in agronomically useful genotypes of sainfoin (Onobrychis spp.) Information on variation among sainfoin species is lacking on thermal dependence of glutathione reductase (B.C. 1.6.4.2.), which plays an important role in the protection of plants from both high and low temperature stresses by preventing harmful oxidation of enzymes and membranes. Our objective was to investigate the interspecific variation for thermal dependency of glutathione reductase in sainfoin. Large variation among species was found for: (i) the minimum apparent Km (0.4-2.5 μM NADPH), (ii) the temperature at which the minimum apparent Km was observed (15°-5°C), and (iii) the thermal kinetic windows (2°-30°C width) over a 15°-45°C temperature gradient. In general, tetraploid species had narrower (≤17°C) thermal kinetic windows than did diploid species (∼30°C), with one exception among the diploids. Within the tetraploid species, the cultivars of O. viciifolia had a broader thermal kinetic window (≥7°C) than the plant introduction (PI 212241, >2 °C) itself.

  20. Temperature-dependent thermal properties of ex vivo liver undergoing thermal ablation.

    Science.gov (United States)

    Guntur, Sitaramanjaneya Reddy; Lee, Kang Il; Paeng, Dong-Guk; Coleman, Andrew John; Choi, Min Joo

    2013-10-01

    Thermotherapy uses a heat source that raises temperatures in the target tissue, and the temperature rise depends on the thermal properties of the tissue. Little is known about the temperature-dependent thermal properties of tissue, which prevents us from accurately predicting the temperature distribution of the target tissue undergoing thermotherapy. The present study reports the key thermal parameters (specific heat capacity, thermal conductivity and heat diffusivity) measured in ex vivo porcine liver while being heated from 20 ° C to 90 ° C and then naturally cooled down to 20 ° C. The study indicates that as the tissue was heated, all the thermal parameters resulted in plots with asymmetric quasi-parabolic curves with temperature, being convex downward with their minima at the turning temperature of 35-40 ° C. The largest change was observed for thermal conductivity, which decreased by 9.6% from its initial value (at 20 ° C) at the turning temperature (35 ° C) and rose by 45% at 90 ° C from its minimum (at 35 ° C). The minima were 3.567 mJ/(m(3) ∙ K) for specific heat capacity, 0.520 W/(m.K) for thermal conductivity and 0.141 mm(2)/s for thermal diffusivity. The minimum at the turning temperature was unique, and it is suggested that it be taken as a characteristic value of the thermal parameter of the tissue. On the other hand, the thermal parameters were insensitive to temperature and remained almost unchanged when the tissue cooled down, indicating that their variations with temperature were irreversible. The rate of the irreversible rise at 35 ° C was 18% in specific heat capacity, 40% in thermal conductivity and 38.3% in thermal diffusivity. The study indicates that the key thermal parameters of ex vivo porcine liver vary largely with temperature when heated, as described by asymmetric quasi-parabolic curves of the thermal parameters with temperature, and therefore, substantial influence on the temperature distribution of the tissue undergoing

  1. HVI Ballistic Limit Characterization of Fused Silica Thermal Panes

    Science.gov (United States)

    Miller, J. E.; Bohl, W. D.; Christiansen, E. L.; Davis, B. A.; Deighton, K. D.

    2015-01-01

    Fused silica window systems are used heavily on crewed reentry vehicles, and they are currently being used on the next generation of US crewed spacecraft, Orion. These systems improve crew situational awareness and comfort, as well as, insulating the reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on a fused silica window system proposed for the Orion spacecraft. A ballistic limit equation that describes the threshold of perforation of a fuse silica pane over a broad range of impact velocities, obliquities and projectile materials is discussed here.

  2. Impact of limiting dimension on thermal conductivity of one-dimensional silicon phononic crystals

    Science.gov (United States)

    Yanagisawa, R.; Maire, J.; Ramiere, A.; Anufriev, R.; Nomura, M.

    2017-03-01

    We present experimental and theoretical investigations on the roles of the limiting dimensions, such as the smallest dimension, surface roughness, and density of holes in the reduction of thermal conductivity of one-dimensional phononic nanostructures at temperatures of 4 and 295 K. We discover that the thermal conductivity does not strongly depend on the period of the phononic crystal nanostructures whereas the surface roughness and the smallest dimension of the structure—the neck—play the most important roles in thermal conductivity reduction. Surface roughness is a very important structural parameter in nanostructures with a characteristic length less than 100 nm in silicon. The importance of the roughness increases as the neck size decreases, and the thermal conductivity of the structure can differ by a factor of four, reaching the thermal conductivity of a small nanowire. The experimental data are analyzed using the Callaway-Holland model of Boltzmann equation and Monte Carlo simulation providing deeper insight into the thermal phonon transport in phononic nanostructures.

  3. Equilibrium limit of thermal conduction and boundary scattering in nanostructures.

    Science.gov (United States)

    Haskins, Justin B; Kınacı, Alper; Sevik, Cem; Çağın, Tahir

    2014-06-28

    Determining the lattice thermal conductivity (κ) of nanostructures is especially challenging in that, aside from the phonon-phonon scattering present in large systems, the scattering of phonons from the system boundary greatly influences heat transport, particularly when system length (L) is less than the average phonon mean free path (MFP). One possible route to modeling κ in these systems is through molecular dynamics (MD) simulations, inherently including both phonon-phonon and phonon-boundary scattering effects in the classical limit. Here, we compare current MD methods for computing κ in nanostructures with both L ⩽ MFP and L ≫ MFP, referred to as mean free path constrained (cMFP) and unconstrained (uMFP), respectively. Using a (10,0) CNT (carbon nanotube) as a benchmark case, we find that while the uMFP limit of κ is well-defined through the use of equilibrium MD and the time-correlation formalism, the standard equilibrium procedure for κ is not appropriate for the treatment of the cMFP limit because of the large influence of boundary scattering. To address this issue, we define an appropriate equilibrium procedure for cMFP systems that, through comparison to high-fidelity non-equilibrium methods, is shown to be the low thermal gradient limit to non-equilibrium results. Further, as a means of predicting κ in systems having L ≫ MFP from cMFP results, we employ an extrapolation procedure based on the phenomenological, boundary scattering inclusive expression of Callaway [Phys. Rev. 113, 1046 (1959)]. Using κ from systems with L ⩽ 3 μm in the extrapolation, we find that the equilibrium uMFP κ of a (10,0) CNT can be predicted within 5%. The equilibrium procedure is then applied to a variety of carbon-based nanostructures, such as graphene flakes (GF), graphene nanoribbons (GNRs), CNTs, and icosahedral fullerenes, to determine the influence of size and environment (suspended versus supported) on κ. Concerning the GF and GNR systems, we find that

  4. Limiting fragmentation in a thermal model with flow

    Energy Technology Data Exchange (ETDEWEB)

    Kumar Tiwari, Swatantra; Sahoo, Raghunath [Indian Institute of Technology Indore, Discipline of Physics, School of Basic Sciences, Simrol, Indore (India)

    2016-12-15

    The property of limiting fragmentation of various observables such as rapidity distributions (dN/dy), elliptic flow (v{sub 2}), average transverse momentum (left angle p{sub T} right angle) etc. of charged particles is observed when they are plotted as a function of rapidity (y) shifted by the beam rapidity (y{sub beam}) for a wide range of energies from AGS to RHIC. Limiting fragmentation (LF) is a well-studied phenomenon as observed in various collision energies and colliding systems experimentally. It is very interesting to verify this phenomenon theoretically. We study such a phenomenon for pion rapidity spectra using our hydrodynamic-like model where the collective flow is incorporated in a thermal model in the longitudinal direction. Our findings advocate the observation of extended longitudinal scaling in the rapidity spectra of pions from AGS to lower RHIC energies, while it is observed to be violated at top RHIC and LHC energies. Prediction of LF hypothesis for Pb+Pb collisions at √(s{sub NN}) = 5.02 TeV is given. (orig.)

  5. On the channel width-dependence of the thermal conductivity in ultra-narrow graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Karamitaheri, Hossein [Department of Electrical Engineering, University of Kashan, Kashan 87317-53153 (Iran, Islamic Republic of); Neophytou, Neophytos, E-mail: N.Neophytou@warwick.ac.uk [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-08-08

    The thermal conductivity of low-dimensional materials and graphene nanoribbons, in particular, is limited by the strength of line-edge-roughness scattering. One way to characterize the roughness strength is the dependency of the thermal conductivity on the channel's width in the form W{sup β}. Although in the case of electronic transport, this dependency is very well studied, resulting in W{sup 6} for nanowires and quantum wells and W{sup 4} for nanoribbons, in the case of phonon transport it is not yet clear what this dependence is. In this work, using lattice dynamics and Non-Equilibrium Green's Function simulations, we examine the width dependence of the thermal conductivity of ultra-narrow graphene nanoribbons under the influence of line edge-roughness. We show that the exponent β is in fact not a single well-defined number, but it is different for different parts of the phonon spectrum depending on whether phonon transport is ballistic, diffusive, or localized. The exponent β takes values β < 1 for semi-ballistic phonon transport, values β ≫ 1 for sub-diffusive or localized phonons, and β = 1 only in the case where the transport is diffusive. The overall W{sup β} dependence of the thermal conductivity is determined by the width-dependence of the dominant phonon modes (usually the acoustic ones). We show that due to the long phonon mean-free-paths, the width-dependence of thermal conductivity becomes a channel length dependent property, because the channel length determines whether transport is ballistic, diffusive, or localized.

  6. Dependence of thermal conductivity on structural parameters in porous samples

    Directory of Open Access Journals (Sweden)

    L. Miettinen

    2012-03-01

    Full Text Available The in-plane thermal conductivity of porous sintered bronze plates was studied both experimentally and numerically. We developed and validated an experimental setup, where the sample was placed in vacuum and heated while its time-dependent temperature field was measured with an infrared camera. The porosity and detailed three-dimensional structure of the samples were determined by X-ray microtomography. Lattice-Boltzmann simulations of thermal conductivity in the tomographic reconstructions of the samples were used to correct the contact area between bronze particles as determined by image analysis from the tomographic reconstructions. Small openings in the apparent contacts could not be detected with the imaging resolution used, and they caused an apparent thermal contact resistance between particles. With this correction included, the behavior of the measured thermal conductivity was successfully explained by an analytical expression, originally derived for regular structures, which involves three structural parameters of the porous structures. There was no simple relationship between heat conductivity and porosity.

  7. Meeting NPDES permit limits for an effluent-dependent stream

    Energy Technology Data Exchange (ETDEWEB)

    Payne, W.L.

    1998-09-01

    When the Savannah River Site in Aiken, South Carolina received a National Pollutant Discharge Elimination System permit containing very low copper and toxicity limits for an effluent-dependent stream, an innovative and cost-effective method to meet them was sought. The South Carolina Department of Health and Environmental Control mandated that compliance with the new limits be achieved within three years of the effective date of the permit. SRS personnel studied various regulatory options for complying with the new limits including Water Effect Ratio, use of a Metals Translator, blending with additional effluents, and outfall relocation. Regulatory options were determined to not be feasible because the receiving stream is effluent dependent. Treatment options were studied after it was determined that none of the regulatory pathways were viable. Corrosion inhibitors were evaluated on a full-scale basis with only limited benefits. Ion exchange was promising, but not cost effective for a high flow effluent with a very low concentration of copper. A treatment wetlands, not normally given consideration for the removal of metals, proved to be the most cost effective method studied and is currently under construction.

  8. Thermal rectification in restructured graphene with locally modulated temperature dependence of thermal conductivity

    Science.gov (United States)

    Arora, Anuj; Hori, Takuma; Shiga, Takuma; Shiomi, Junichiro

    2017-10-01

    We study thermal rectification (TR) in a selectively restructured graphene by performing deviational phonon Monte Carlo (MC) simulations with frequency-dependent phonon transport properties obtained from first principles. The restructuring is achieved by introducing vacancy defects in a portion of graphene. The defects significantly change phonon transport properties, resulting in a modulation of temperature dependence of thermal conductivity. With this modulated temperature dependence, we predict TR ratio through a Fourier's-law-based iterative scheme (FIS), where heat flow through the system is analyzed by solving the Fourier's law of heat conduction with spatially varying temperature-dependent thermal conductivity. To identify structure parameters for maximal TR ratio, we investigate the influence of defect size, volume percentage of defects, and system (consisting of defective and nondefective regions) length through FIS analysis. As a result, we find that the TR ratio is mainly a function of length of defective and nondefective regions and volume percentage of defect, and it is mostly independent of defect size. A longer (of the order of 10 μm) nondefective side, coupled to a shorter (of the order of 100 nm) defective side, can lead to large TR ratios. Finally, MC simulation for the restructured graphene (full system) is performed to verify the predictions from FIS analysis. The full system calculations give similar trends but with enhanced TR ratios up to 70% for the temperature range of 200-500 K.

  9. Size-dependent axisymmetric vibration of functionally graded circular plates in bifurcation/limit point instability

    Science.gov (United States)

    Ashoori, A. R.; Vanini, S. A. Sadough; Salari, E.

    2017-04-01

    In the present paper, vibration behavior of size-dependent functionally graded (FG) circular microplates subjected to thermal loading are carried out in pre/post-buckling of bifurcation/limit-load instability for the first time. Two kinds of frequently used thermal loading, i.e., uniform temperature rise and heat conduction across the thickness direction are considered. Thermo-mechanical material properties of FG plate are supposed to vary smoothly and continuously throughout the thickness based on power law model. Modified couple stress theory is exploited to describe the size dependency of microplate. The nonlinear governing equations of motion and associated boundary conditions are extracted through generalized form of Hamilton's principle and von-Karman geometric nonlinearity for the vibration analysis of circular FG plates including size effects. Ritz finite element method is then employed to construct the matrix representation of governing equations which are solved by two different strategies including Newton-Raphson scheme and cylindrical arc-length method. Moreover, in the following a parametric study is accompanied to examine the effects of the several parameters such as material length scale parameter, temperature distributions, type of buckling, thickness to radius ratio, boundary conditions and power law index on the dimensionless frequency of post-buckled/snapped size-dependent FG plates in detail. It is found that the material length scale parameter and thermal loading have a significant effect on vibration characteristics of size-dependent circular FG plates.

  10. Limits for density dependent time inhomogeneous Markov processes.

    Science.gov (United States)

    Smith, Andrew G

    2015-10-01

    A new functional law of large numbers to approximate a time inhomogeneous Markov process that is only density dependent in the limit as an index parameter goes to infinity is developed. This extends previous results by other authors to a broader class of Markov processes while relaxing some of the conditions required for those results to hold. This result is applied to a stochastic metapopulation model that accounts for spatial structure as well as within patch dynamics with the novel addition of time dependent dynamics. The resulting nonautonomous differential equation is analysed to provide conditions for extinction and persistence for a number of examples. This condition shows that the migration of a species will positively impact the reproduction in less populated areas while negatively impacting densely populated areas. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  11. Generalized linear models for categorical and continuous limited dependent variables

    CERN Document Server

    Smithson, Michael

    2013-01-01

    Introduction and OverviewThe Nature of Limited Dependent VariablesOverview of GLMsEstimation Methods and Model EvaluationOrganization of This BookDiscrete VariablesBinary VariablesLogistic RegressionThe Binomial GLMEstimation Methods and IssuesAnalyses in R and StataExercisesNominal Polytomous VariablesMultinomial Logit ModelConditional Logit and Choice ModelsMultinomial Processing Tree ModelsEstimation Methods and Model EvaluationAnalyses in R and StataExercisesOrdinal Categorical VariablesModeling Ordinal Variables: Common Practice versus Best PracticeOrdinal Model AlternativesCumulative Mod

  12. Thermal limits for growth and reproduction in the desert pupfish, Cyprinodon n. nevadensis

    Energy Technology Data Exchange (ETDEWEB)

    Gerking, S.D.; Lee, R.M.

    1979-01-01

    The thermal limits for growth of the desert pupfish (Cyprinodon n. nevadensis) were determined in seven-week laboratory feeding experiments at three rations (1.5, 3.0 and 4.5% body weight day) of Tetra-min prepared food and seven temperatures (12, 16, 20, 24, 28, 32, and 36 C). Curves of specific growth rates (% dry weight gain/day) as related to temperature were skewed to the left at the three rations. Growth was inhibited at 12, 16 and 36 C. Fish at the lower two temperatures were torpid and lacked appetite; the higher temperature fish did not eat sufficient food to match the high metabolic cost. The thermal scope for growth was narrowed as ration decreased and as age/size increased. Taking these factors into account, the thermal limits for growth of immature pupfish feeding at moderate to high rates were 17.5 to 31.0 C with optimum growth achieved at 22.0 C. Successful reproduction depends on egg production and egg viability.

  13. Tail-weighted dependence measures with limit being the tail dependence coefficient

    KAUST Repository

    Lee, David

    2017-12-02

    For bivariate continuous data, measures of monotonic dependence are based on the rank transformations of the two variables. For bivariate extreme value copulas, there is a family of estimators (Formula presented.), for (Formula presented.), of the extremal coefficient, based on a transform of the absolute difference of the α power of the ranks. In the case of general bivariate copulas, we obtain the probability limit (Formula presented.) of (Formula presented.) as the sample size goes to infinity and show that (i) (Formula presented.) for (Formula presented.) is a measure of central dependence with properties similar to Kendall\\'s tau and Spearman\\'s rank correlation, (ii) (Formula presented.) is a tail-weighted dependence measure for large α, and (iii) the limit as (Formula presented.) is the upper tail dependence coefficient. We obtain asymptotic properties for the rank-based measure (Formula presented.) and estimate tail dependence coefficients through extrapolation on (Formula presented.). A data example illustrates the use of the new dependence measures for tail inference.

  14. Thermal Fatigue Limitations of Continuous Fiber Metal Matrix Composites

    Science.gov (United States)

    Halford, Gary R.; Arya, Vinod K.

    1997-01-01

    The potential structural benefits of unidirectional, continuous-fiber, metal matrix composites (MMC's) are legendary. When compared to their monolithic matrices, MMC's possess superior properties such as higher stiffness and tensile strength, and lower coefficient of thermal expansion in the direction of the reinforcing fibers. As an added bonus, the MMC density will be lower if the fibers are less dense than the matrix matErial they replace. The potential has been demonstrated unequivocally both analytically and experimentally, especially at ambient temperatures. Successes prompted heavily-funded National efforts within the United States (USAF and NASA) and elsewhere to extend the promise of MMC's into the temperature regime wherein creep, stress relaxation, oxidation, and thermal fatigue damage mechanisms lurk. This is the very regime for which alternative high-temperature materials are becoming mandatory, since further enhancement of state- of-the-art monolithic alloys is rapidly approaching a point of diminishing returns.

  15. Macroevolution of thermal tolerance in intertidal crabs from Neotropical provinces: A phylogenetic comparative evaluation of critical limits.

    Science.gov (United States)

    Faria, Samuel C; Faleiros, Rogério O; Brayner, Fábio A; Alves, Luiz C; Bianchini, Adalto; Romero, Carolina; Buranelli, Raquel C; Mantelatto, Fernando L; McNamara, John C

    2017-05-01

    Thermal tolerance underpins most biogeographical patterns in ectothermic animals. Macroevolutionary patterns of thermal limits have been historically evaluated, but a role for the phylogenetic component in physiological variation has been neglected. Three marine zoogeographical provinces are recognized throughout the Neotropical region based on mean seawater temperature (Tm): the Brazilian (Tm = 26 °C), Argentinian (Tm = 15 °C), and Magellanic (Tm = 9 °C) provinces. Microhabitat temperature (MHT) was measured, and the upper (UL 50) and lower (LL 50) critical thermal limits were established for 12 eubrachyuran crab species from intertidal zones within these three provinces. A molecular phylogenetic analysis was performed by maximum likelihood using the 16S mitochondrial gene, also considering other representative species to enable comparative evaluations. We tested for: (1) phylogenetic pattern of MHT, UL 50, and LL 50; (2) effect of zoogeographical province on the evolution of both limits; and (3) evolutionary correlation between MHT and thermal limits. MHT and UL 50 showed strong phylogenetic signal at the species level while LL 50 was unrelated to phylogeny, suggesting a more plastic evolution. Province seems to have affected the evolution of thermal tolerance, and only UL 50 was dependent on MHT. UL 50 was similar between the two northern provinces compared to the southernmost while LL 50 differed markedly among provinces. Apparently, critical limits are subject to different environmental pressures and thus manifest unique evolutionary histories. An asymmetrical macroevolutionary scenario for eubrachyuran thermal tolerance seems likely, as the critical thermal limits are differentially inherited and environmentally driven.

  16. Measuring the size dependence of thermal conductivity of suspended graphene disks using null-point scanning thermal microscopy.

    Science.gov (United States)

    Hwang, Gwangseok; Kwon, Ohmyoung

    2016-03-07

    Using null-point scanning thermal microscopy (NP SThM), we have measured and analyzed the size dependence of the thermal conductivity of graphene. To do so, we rigorously re-derived the principal equation of NP SThM in terms of thermal property measurements so as to explain how this technique can be effectively used to quantitatively measure the local thermal resistance with nanoscale spatial resolution. This technique has already been proven to resolve the major problems of conventional SThM, and to quantitatively measure the temperature profile. Using NP SThM, we measured the variation in the thermal resistance of suspended chemical vapor deposition (CVD)-grown graphene disks with radii of 50-3680 nm from the center to the edge with respect to the size. By thoroughly analyzing the size dependence of the thermal resistance, we show that, with increasing graphene size, the ballistic resistance becomes more dominant in the thermal resistance experienced by a heat source of finite size and that the thermal conductivity experienced by such a heat source can even decrease. The results of this study reveal that the thermal conductivity of graphene detected by a heat source depends on the size of the heat source relative to that of the suspended graphene and on how the heat source and graphene are connected. As demonstrated in this study, NP SThM will be very useful for quantitative thermal characterization of not only CVD-grown graphene but also various other nanomaterials and nanodevices.

  17. The Limited Capacity of Sleep-Dependent Memory Consolidation

    Directory of Open Access Journals (Sweden)

    Gordon B Feld

    2016-09-01

    Full Text Available Sleep supports memory consolidation. However, the conceptually important influence of the amount of items encoded in a memory test on this effect has not been investigated. In two experiments, participants (n=101 learned lists of word-pairs varying in length (40, 160, 320 word-pairs in the evening before a night of sleep (sleep group or of sleep deprivation (wake group. After 36 h (including a night allowing recovery sleep retrieval was tested. Compared with wakefulness, post-learning sleep enhanced retention for the 160 word-pair condition (p < 0.01, importantly, this effect completely vanished for the 320 word-pair condition. This result indicates a limited capacity for sleep-dependent memory consolidation, which is consistent with an active system consolidation view on sleep’s role for memory, if it is complemented by processes of active forgetting and/or gist abstraction. Whereas the absolute benefit from sleep should have increased with increasing amounts of successfully encoded items, if sleep only passively protected memory from interference. Moreover, the finding that retention performance was significantly diminished for the 320 word-pair condition compared to the 160 word-pair condition in the sleep group, makes it tempting to speculate that with increasing loads of information encoded during wakefulness, sleep might favour processes of forgetting over consolidation.

  18. HUMAN FAILURE EVENT DEPENDENCE: WHAT ARE THE LIMITS

    Energy Technology Data Exchange (ETDEWEB)

    Herberger, Sarah M.; Boring, Ronald L.

    2016-10-01

    Abstract Objectives: This paper discusses the differences between classical human reliability analysis (HRA) dependence and the full spectrum of probabilistic dependence. Positive influence suggests an error increases the likelihood of subsequent errors or success increases the likelihood of subsequent success. Currently the typical method for dependence in HRA implements the Technique for Human Error Rate Prediction (THERP) positive dependence equations. This assumes that the dependence between two human failure events varies at discrete levels between zero and complete dependence (as defined by THERP). Dependence in THERP does not consistently span dependence values between 0 and 1. In contrast, probabilistic dependence employs Bayes Law, and addresses a continuous range of dependence. Methods: Using the laws of probability, complete dependence and maximum positive dependence do not always agree. Maximum dependence is when two events overlap to their fullest amount. Maximum negative dependence is the smallest amount that two events can overlap. When the minimum probability of two events overlapping is less than independence, negative dependence occurs. For example, negative dependence is when an operator fails to actuate Pump A, thereby increasing his or her chance of actuating Pump B. The initial error actually increases the chance of subsequent success. Results: Comparing THERP and probability theory yields different results in certain scenarios; with the latter addressing negative dependence. Given that most human failure events are rare, the minimum overlap is typically 0. And when the second event is smaller than the first event the max dependence is less than 1, as defined by Bayes Law. As such alternative dependence equations are provided along with a look-up table defining the maximum and maximum negative dependence given the probability of two events. Conclusions: THERP dependence has been used ubiquitously for decades, and has provided approximations of

  19. Possibilities and Limitations of Thermally Activated Building Systems

    DEFF Research Database (Denmark)

    Behrendt, Benjamin

    The strong political market drive towards energy savings in the building sector calls for efficient solutions. Using so called low temperature heating and high temperature cooling systems such as for instance thermally activated building systems (TABS) has a significant impact on the required...... tool for the early assessment for the use of TABS in modern Buildings. Not only is it possible to runs simulations in accordance to ISO 11855-4 but also to determine the minimal required plant sizes for cooling, the duration until overheating, the maximum internal temperatures for insufficient plant...... will be mostly needed to operate the building within acceptable boundaries. It will also allow the user to see if dehumidification will be needed for undisturbed operation of TABS. With the combination of both tools it is possible to provide a holistic evaluation of a building proposal at a very early design...

  20. Limited capacity for developmental thermal acclimation in three tropical wrasses

    Science.gov (United States)

    Motson, K.; Donelson, J. M.

    2017-06-01

    For effective conservation and management of marine systems, it is essential that we understand the biological impacts of and capacity for acclimation to increased ocean temperatures. This study investigated for the first time the effects of developing in projected warmer ocean conditions in the tropical wrasse species: Halichoeres melanurus, Halichoeres miniatus and Thalassoma amblycephalum. New recruits were reared for 11 weeks in control (29 °C) and +2 °C (31 °C) temperature treatments, consistent with predicted increases in sea surface temperature by 2100. A broad range of key attributes and performance parameters was tested, including aerobic metabolism, swimming ability, burst escape performance and physical condition. Response latency of burst performance was the only performance parameter in which evidence of beneficial thermal developmental acclimation was found, observed only in H. melanurus. Generally, development in the +2 °C treatment came at a significant cost to all species, resulting in reduced growth and physical condition, as well as metabolic and swimming performance relative to controls. Development in +2 °C conditions exacerbated the effects of warming on aerobic metabolism and swimming ability, compared to short-term warming effects. Burst escape performance parameters were only mildly affected by development at +2 °C, with non-locomotor performance (response latency) showing greater thermal sensitivity than locomotor performance parameters. These results indicate that the effects of future climate change on tropical wrasses would be underestimated with short-term testing. This study highlights the importance of holistic, longer-term developmental experimental approaches, with warming found to yield significant, species-specific responses in all parameters tested.

  1. Nano-Kelvin thermometry and temperature control: beyond the thermal noise limit

    CERN Document Server

    Weng, Wenle; Stace, Thomas M; Campbell, Geoff; Baynes, Fred N; Luiten, Andre N

    2014-01-01

    We demonstrate thermometry with a resolution of 80 $\\mathrm{nK} / \\sqrt{\\mathrm{Hz}}$ using an isotropic crystalline whispering-gallery mode resonator based on a dichroic dual-mode technique. We simultaneously excite two modes that have a mode frequency ratio very close to two ($\\pm0.3$ppm). The wavelength- and temperature-dependence of the refractive index means that the frequency difference between these modes is an ultra-sensitive proxy of the resonator temperature. This approach to temperature sensing automatically suppresses sensitivity to thermal expansion and vibrationally induced changes of the resonator. We also demonstrate active suppression of temperature fluctuations in the resonator by controlling the intensity of the driving laser. The residual temperature fluctuations are shown to be below the limits set by fundamental thermodynamic fluctuations of the resonator material.

  2. Exploring the limits of identifying sub-pixel thermal features using ASTER TIR data

    Science.gov (United States)

    Vaughan, R.G.; Keszthelyi, L.P.; Davies, A.G.; Schneider, D.J.; Jaworowski, C.; Heasler, H.

    2010-01-01

    Understanding the characteristics of volcanic thermal emissions and how they change with time is important for forecasting and monitoring volcanic activity and potential hazards. Satellite instruments view volcanic thermal features across the globe at various temporal and spatial resolutions. Thermal features that may be a precursor to a major eruption, or indicative of important changes in an on-going eruption can be subtle, making them challenging to reliably identify with satellite instruments. The goal of this study was to explore the limits of the types and magnitudes of thermal anomalies that could be detected using satellite thermal infrared (TIR) data. Specifically, the characterization of sub-pixel thermal features with a wide range of temperatures is considered using ASTER multispectral TIR data. First, theoretical calculations were made to define a "thermal mixing detection threshold" for ASTER, which quantifies the limits of ASTER's ability to resolve sub-pixel thermal mixing over a range of hot target temperatures and % pixel areas. Then, ASTER TIR data were used to model sub-pixel thermal features at the Yellowstone National Park geothermal area (hot spring pools with temperatures from 40 to 90 ??C) and at Mount Erebus Volcano, Antarctica (an active lava lake with temperatures from 200 to 800 ??C). Finally, various sources of uncertainty in sub-pixel thermal calculations were quantified for these empirical measurements, including pixel resampling, atmospheric correction, and background temperature and emissivity assumptions.

  3. 2-D CFD time-dependent thermal-hydraulic simulations of CANDU-6 moderator flows

    Energy Technology Data Exchange (ETDEWEB)

    Mehdi Zadeh, Foad [Department of Engineering Physics/Polytechnique Montréal, Montréal, QC (Canada); Étienne, Stéphane [Department of Mechanical Engineering/Polytechnique Montréal, Montréal, QC (Canada); Teyssedou, Alberto, E-mail: alberto.teyssedou@polymtl.ca [Department of Engineering Physics/Polytechnique Montréal, Montréal, QC (Canada)

    2016-12-01

    Highlights: • 2-D time-dependent CFD simulations of CANDU-6 moderator flows are presented. • A thermal-hydraulic code using thermal physical fluid properties is used. • The numerical approach and convergence is validated against available data. • Flow configurations are correlated using Richardson’s number. • Frequency components indicate moderator flow oscillations vs. Richardson numbers. - Abstract: The distribution of the fluid temperature and mass density of the moderator flow in CANDU-6 nuclear power reactors may affect the reactivity coefficient. For this reason, any possible moderator flow configuration and consequently the corresponding temperature distributions must be studied. In particular, the variations of the reactivity may result in major safety issues. For instance, excessive temperature excursions in the vicinity of the calandria tubes nearby local flow stagnation zones, may bring about partial boiling. Moreover, steady-state simulations have shown that for operating condition, intense buoyancy forces may be dominant, which can trigger a thermal stratification. Therefore, the numerical study of the time-dependent flow transition to such a condition, is of fundamental safety concern. Within this framework, this paper presents detailed time-dependent numerical simulations of CANDU-6 moderator flow for a wide range of flow conditions. To get a better insight of the thermal-hydraulic phenomena, the simulations were performed by covering long physical-time periods using an open-source code (Code-Saturne V3) developed by Électricité de France. The results show not only a region where the flow is characterized by coherent structures of flow fluctuations but also the existence of two limit cases where fluid oscillations disappear almost completely.

  4. Thermal limit for metazoan life in question: in vivo heat tolerance of the Pompeii worm

    National Research Council Canada - National Science Library

    Ravaux, Juliette; Hamel, Gérard; Zbinden, Magali; Tasiemski, Aurélie A; Boutet, Isabelle; Léger, Nelly; Tanguy, Arnaud; Jollivet, Didier; Shillito, Bruce

    2013-01-01

    The thermal limit for metazoan life, expected to be around 50°C, has been debated since the discovery of the Pompeii worm Alvinella pompejana, which colonizes black smoker chimney walls at deep-sea vents...

  5. Haar Wavelet Collocation Method for Thermal Analysis of Porous Fin with Temperature-dependent Thermal Conductivity and Internal Heat Generation

    Directory of Open Access Journals (Sweden)

    George OGUNTALA

    2017-08-01

    Full Text Available In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.

  6. Dependence of thermal conductivity in micro to nano silica

    Indian Academy of Sciences (India)

    This work presents the measurement of thermal conductivity of nano-silica particles using needle probe method. The validation test of thermal probe was conducted on ice and THF hydrates using our experimental set up and the results are satisfactory when compared with the literature data. The nano silica used in this ...

  7. Assessment of Thermal Maturity Trends in Devonian–Mississippian Source Rocks Using Raman Spectroscopy: Limitations of Peak-Fitting Method

    Directory of Open Access Journals (Sweden)

    Jason S. Lupoi

    2017-09-01

    Full Text Available The thermal maturity of shale is often measured by vitrinite reflectance (VRo. VRo measurements for the Devonian–Mississippian black shale source rocks evaluated herein predicted thermal immaturity in areas where associated reservoir rocks are oil-producing. This limitation of the VRo method led to the current evaluation of Raman spectroscopy as a suitable alternative for developing correlations between thermal maturity and Raman spectra. In this study, Raman spectra of Devonian–Mississippian black shale source rocks were regressed against measured VRo or sample-depth. Attempts were made to develop quantitative correlations of thermal maturity. Using sample-depth as a proxy for thermal maturity is not without limitations as thermal maturity as a function of depth depends on thermal gradient, which can vary through time, subsidence rate, uplift, lack of uplift, and faulting. Correlations between Raman data and vitrinite reflectance or sample-depth were quantified by peak-fitting the spectra. Various peak-fitting procedures were evaluated to determine the effects of the number of peaks and maximum peak widths on correlations between spectral metrics and thermal maturity. Correlations between D-frequency, G-band full width at half maximum (FWHM, and band separation between the G- and D-peaks and thermal maturity provided some degree of linearity throughout most peak-fitting assessments; however, these correlations and those calculated from the G-frequency, D/G FWHM ratio, and D/G peak area ratio also revealed a strong dependence on peak-fitting processes. This dependency on spectral analysis techniques raises questions about the validity of peak-fitting, particularly given the amount of subjective analyst involvement necessary to reconstruct spectra. This research shows how user interpretation and extrapolation affected the comparability of different samples, the accuracy of generated trends, and therefore, the potential of the Raman spectral

  8. Can oxygen set thermal limits in an insect and drive gigantism?

    Directory of Open Access Journals (Sweden)

    Wilco C E P Verberk

    Full Text Available BACKGROUND: Thermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic. METHODOLOGY/PRINCIPAL FINDINGS: Here we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa and hyperoxia (36 kPa. We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels. CONCLUSIONS/SIGNIFICANCE: These findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods.

  9. DETERMINATION OF TEMPERATURE DISTRIBUTION FOR ANNULAR FINS WITH TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY BY HPM

    Directory of Open Access Journals (Sweden)

    Davood Domairry Ganji

    2011-01-01

    Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.

  10. Maximum time-dependent space-charge limited diode currents

    Energy Technology Data Exchange (ETDEWEB)

    Griswold, M. E. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Fisch, N. J. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2016-01-15

    Recent papers claim that a one dimensional (1D) diode with a time-varying voltage drop can transmit current densities that exceed the Child-Langmuir (CL) limit on average, apparently contradicting a previous conjecture that there is a hard limit on the average current density across any 1D diode, as t → ∞, that is equal to the CL limit. However, these claims rest on a different definition of the CL limit, namely, a comparison between the time-averaged diode current and the adiabatic average of the expression for the stationary CL limit. If the current were considered as a function of the maximum applied voltage, rather than the average applied voltage, then the original conjecture would not have been refuted.

  11. Thermal physiology and vertical zonation of intertidal animals: optima, limits, and costs of living.

    Science.gov (United States)

    Somero, George N

    2002-08-01

    Temperature's pervasive effects on physiological systems are reflected in the suite of temperature-adaptive differences observed among species from different thermal niches, such as species with different vertical distributions (zonations) along the subtidal to intertidal gradient. Among the physiological traits that exhibit adaptive variation related to vertical zonation are whole organism thermal tolerance, heart function, mitochondrial respiration, membrane static order (fluidity), action potential generation, protein synthesis, heat-shock protein expression, and protein thermal stability. For some, but not all, of these thermally sensitive traits acclimatization leads to adaptive shifts in thermal optima and limits. The costs associated with repairing thermal damage and adapting systems through acclimatization may contribute importantly to energy budgets. These costs arise from such sources as: (i) activation and operation of the heat-shock response, (ii) replacement of denatured proteins that have been removed through proteolysis, (iii) restructuring of cellular membranes ("homeoviscous" adaptation), and (iv) pervasive shifts in gene expression (as gauged by using DNA microarray techniques). The vertical zonation observed in rocky intertidal habitats thus may reflect two distinct yet closely related aspects of thermal physiology: (i) intrinsic interspecific differences in temperature sensitivities of physiological systems, which establish thermal optima and tolerance limits for species; and (ii) 'cost of living' considerations arising from sub-lethal perturbation of these physiological systems, which may establish an energetics-based limitation to the maximal height at which a species can occur. Quantifying the energetic costs arising from heat stress represents an important challenge for future investigations.

  12. Critical thermal limits affected differently by developmental and adult thermal fluctuations.

    Science.gov (United States)

    Salachan, Paul Vinu; Sørensen, Jesper Givskov

    2017-12-01

    Means and variances of the environmental thermal regime play an important role in determining the fitness of terrestrial ectotherms. Adaptive phenotypic responses induced by heterogeneous temperatures have been shown to be mediated by molecular pathways independent of the classic heat shock responses; however, an in-depth understanding of plasticity induced by fluctuating temperatures is still lacking. We investigated high and low temperature acclimation induced by fluctuating thermal regimes at two different mean temperatures, at two different amplitudes of fluctuation and across the developmental and adult life stages of Drosophila melanogaster For developmental acclimation, we found mildly detrimental effects of high-amplitude fluctuations for critical thermal minima, while the critical thermal maxima showed a beneficial response to higher amplitude fluctuations. For adult acclimation involving shifts between fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly, we also found that the effect of fluctuations at any life stage was gradually lost with prolonged adult maintenance, suggesting a more prominent effect of fluctuations during developmental compared with adult acclimation in D.melanogaster. © 2017. Published by The Company of Biologists Ltd.

  13. Tracer-based prediction of thermal reservoir lifetime: scope, limitations, and the role of thermosensitive tracers

    Science.gov (United States)

    Ghergut, I.; Behrens, H.; Karmakar, S.; Licha, T.; Nottebohm, M.; Sauter, M.

    2012-04-01

    Thermal-lifetime prediction is a traditional endeavour of inter-well tracer tests conducted in geothermal reservoirs. Early tracer test signals (detectable within the first few years of operation) are expected to correlate with late-time production temperature evolutions ('thermal breakthrough', supposed to not occur before some decades of operation) of a geothermal reservoir. Whenever a geothermal reservoir can be described as a single-fracture system, its thermal lifetime will, ideally, be determined by two parameters (say, fracture aperture and porosity), whose inversion from conservative-tracer test signals is straightforward and non-ambiguous (provided that the tracer tests, and their interpretation, are performed in accordance to the rules of the art). However, as soon as only 'few more' fractures are considered, this clear-cut correlation is broken. A given geothermal reservoir can simultaneously feature a single-fracture behaviour, in terms of heat transport, and a multiple-fracture behaviour, in terms of solute tracer transport (or vice-versa), whose effective values of fracture apertures, spacings, and porosities are essentially uncorrelated between heat and solute tracers. Solute transport parameters derived from conservative-tracer tests will no longer characterize the heat transport processes (and thus temperature evolutions) taking place in the same reservoir. Parameters determining its thermal lifetime will remain 'invisible' to conservative tracers in inter-well tests. We demonstrate this issue at the example of a five-fracture system, representing a deep-geothermal reservoir, with well-doublet placement inducing fluid flow 'obliquely' to the fractures. Thermal breakthrough in this system is found to strongly depend on fracture apertures, whereas conservative-solute tracer signals from inter-well tests in the same system do not show a clear-cut correlation with fracture apertures. Only by using thermosensitive substances as tracers, a reliable

  14. Critical thermal limits affected differently by developmental and adult thermal fluctuations

    DEFF Research Database (Denmark)

    Salachan, Paul Vinu; Sørensen, Jesper Givskov

    2017-01-01

    Means and variances of the environmental thermal regime play an important role in determining the fitness of terrestrial ectotherms. Adaptive phenotypic responses induced by heterogeneous temperatures have been shown to be mediated by molecular pathways independent of the classic heat shock...... responses, however, an in-depth understanding of plasticity induced by fluctuating temperatures is still lacking. We investigated high and low temperature acclimation induced by fluctuating thermal regimes at two different mean temperatures, at two different amplitudes of fluctuation and across...... fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly...

  15. Role of acoustic phonons in frequency dependent electronic thermal conductivity of graphene

    Science.gov (United States)

    Bhalla, Pankaj

    2017-03-01

    We study the effect of the electron-phonon interaction on the finite frequency dependent electronic thermal conductivity of two dimensional graphene. We calculate it for various acoustic phonons present in graphene and characterized by different dispersion relations using the memory function approach. It is found that the electronic thermal conductivity κe (T) in the zero frequency limit follows different power law for the longitudinal/transverse and the flexural acoustic phonons. For the longitudinal/transverse phonons, κe (T) ∼T-1 at the low temperature and saturates at the high temperature. These signatures qualitatively agree with the results calculated by solving the Boltzmann equation analytically and numerically. Similarly, for the flexural phonons, we find that κe (T) shows T 1 / 2 law at the low temperature and then saturates at the high temperature. In the finite frequency regime, we observe that the real part of the electronic thermal conductivity, Re [κe (ω , T) ] follows ω-2 behavior at the low frequency and becomes frequency independent at the high frequency.

  16. SIMPLE limits on spin-dependent WIMP interactions

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Ta [Centro de Fisica Nuclear, Universidade de Lisboa, 1649-003 Lisbon (Portugal); Giuliani, F [Centro de Fisica Nuclear, Universidade de Lisboa, 1649-003 Lisbon (Portugal); Morlat, T [Centro de Fisica Nuclear, Universidade de Lisboa, 1649-003 Lisbon (Portugal); Collar, Ji [Department of Physics, University of Chicago, Chicago IL, 60637 (United States); Limagne, D [INSP - UMR 7588 CNRS, Universites Paris 7 and 6, 75251 Paris (France); Waysand, G [INSP - UMR 7588 CNRS, Universites Paris 7 and 6, 75251 Paris (France); Puibasset, J [INSP - UMR 7588 CNRS, Universites Paris 7 and 6, 75251 Paris (France); Miley, Hs [Pacific Northwest National Laboratory, Richland, WA 99352 USA (United States); Auguste, M [Laboratoire Souterrain a Bas Bruit, 84400 Rustrel-Pays d' Apt (France); Boyer, D [Laboratoire Souterrain a Bas Bruit, 84400 Rustrel-Pays d' Apt (France); Cavaillou, A [Laboratoire Souterrain a Bas Bruit, 84400 Rustrel-Pays d' Apt (France); Marques, Jg [Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Oliveira, C [Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Fernandes, Ac [Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Ramos, Ar [Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Felizardo, M [Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Martins, Rc [Department of Electronics, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

    2006-05-15

    An improved SIMPLE experiment comprising four superheated droplet detectors with a total exposure of 0.42 kg.d yields {approx}factor 10 improvement in the previously-reported results. Despite the low exposure, the result provides restrictions on the allowed phase space of spin-dependent coupling strengths almost equivalent to those from the significantly larger exposure NAIAD-CDMS/ZEPLIN searches.

  17. Thermal Aware Floorplanning Incorporating Temperature Dependent Wire Delay Estimation

    DEFF Research Database (Denmark)

    Winther, AndreasThor; Liu, Wei; Nannarelli, Alberto

    2015-01-01

    Temperature has a negative impact on metal resistance and thus wire delay. In state-of-the-art VLSI circuits, large thermal gradients usually exist due to the uneven distribution of heat sources. The difference in wire temperature can lead to performance mismatch because wires of the same length ...

  18. Dependence of thermal conductivity in micro to nano silica

    Indian Academy of Sciences (India)

    The validation test of thermal probe was conducted on ice and THF hydrates using our experimental set up and the results are satisfactory when compared with the literature data. ... power supply leads were sol- dered to them. The probe normally consisted of an electri- cal heater, a temperature sensor and a thermocouple.

  19. Oxygen- and capacity-limited thermal tolerance: bridging ecology and physiology.

    Science.gov (United States)

    Pörtner, Hans-O; Bock, Christian; Mark, Felix C

    2017-08-01

    Observations of climate impacts on ecosystems highlight the need for an understanding of organismal thermal ranges and their implications at the ecosystem level. Where changes in aquatic animal populations have been observed, the integrative concept of oxygen- and capacity-limited thermal tolerance (OCLTT) has successfully characterised the onset of thermal limits to performance and field abundance. The OCLTT concept addresses the molecular to whole-animal mechanisms that define thermal constraints on the capacity for oxygen supply to the organism in relation to oxygen demand. The resulting 'total excess aerobic power budget' supports an animal's performance (e.g. comprising motor activity, reproduction and growth) within an individual's thermal range. The aerobic power budget is often approximated through measurements of aerobic scope for activity (i.e. the maximum difference between resting and the highest exercise-induced rate of oxygen consumption), whereas most animals in the field rely on lower (i.e. routine) modes of activity. At thermal limits, OCLTT also integrates protective mechanisms that extend time-limited tolerance to temperature extremes - mechanisms such as chaperones, anaerobic metabolism and antioxidative defence. Here, we briefly summarise the OCLTT concept and update it by addressing the role of routine metabolism. We highlight potential pitfalls in applying the concept and discuss the variables measured that led to the development of OCLTT. We propose that OCLTT explains why thermal vulnerability is highest at the whole-animal level and lowest at the molecular level. We also discuss how OCLTT captures the thermal constraints on the evolution of aquatic animal life and supports an understanding of the benefits of transitioning from water to land. © 2017. Published by The Company of Biologists Ltd.

  20. A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations

    DEFF Research Database (Denmark)

    Wu, Rui; Wang, Huai; Pedersen, Kristian Bonderup

    2016-01-01

    A basic challenge in the IGBT transient simulation study is to obtain the realistic junction temperature, which demands not only accurate electrical simulations but also precise thermal impedance. This paper proposed a transient thermal model for IGBT junction temperature simulations during short...... circuits or overloads. The updated Cauer thermal model with varying thermal parameters is obtained by means of FEM thermal simulations with temperature-dependent physical parameters. The proposed method is applied to a case study of a 1700 V/1000 A IGBT module. Furthermore, a testing setup is built up...

  1. Dimension- and shape-dependent thermal transport in nano-patterned thin films investigated by scanning thermal microscopy

    Science.gov (United States)

    Ge, Yunfei; Zhang, Yuan; Weaver, Jonathan M. R.; Dobson, Phillip S.

    2017-12-01

    Scanning thermal microscopy (SThM) is a technique which is often used for the measurement of the thermal conductivity of materials at the nanometre scale. The impact of nano-scale feature size and shape on apparent thermal conductivity, as measured using SThM, has been investigated. To achieve this, our recently developed topography-free samples with 200 and 400 nm wide gold wires (50 nm thick) of length of 400–2500 nm were fabricated and their thermal resistance measured and analysed. This data was used in the development and validation of a rigorous but simple heat transfer model that describes a nanoscopic contact to an object with finite shape and size. This model, in combination with a recently proposed thermal resistance network, was then used to calculate the SThM probe signal obtained by measuring these features. These calculated values closely matched the experimental results obtained from the topography-free sample. By using the model to analyse the dimensional dependence of thermal resistance, we demonstrate that feature size and shape has a significant impact on measured thermal properties that can result in a misinterpretation of material thermal conductivity. In the case of a gold nanowire embedded within a silicon nitride matrix it is found that the apparent thermal conductivity of the wire appears to be depressed by a factor of twenty from the true value. These results clearly demonstrate the importance of knowing both probe-sample thermal interactions and feature dimensions as well as shape when using SThM to quantify material thermal properties. Finally, the new model is used to identify the heat flux sensitivity, as well as the effective contact size of the conventional SThM system used in this study.

  2. Equilibrium Limit of Boundary Scattering in Carbon Nanostructures: Molecular Dynamics Calculations of Thermal Transport

    Science.gov (United States)

    Haskins, Justin; Kinaci, Alper; Sevik, Cem; Cagin, Tahir

    2012-01-01

    It is widely known that graphene and many of its derivative nanostructures have exceedingly high reported thermal conductivities (up to 4000 W/mK at 300 K). Such attractive thermal properties beg the use of these structures in practical devices; however, to implement these materials while preserving transport quality, the influence of structure on thermal conductivity should be thoroughly understood. For graphene nanostructures, having average phonon mean free paths on the order of one micron, a primary concern is how size influences the potential for heat conduction. To investigate this, we employ a novel technique to evaluate the lattice thermal conductivity from the Green-Kubo relations and equilibrium molecular dynamics in systems where phonon-boundary scattering dominates heat flow. Specifically, the thermal conductivities of graphene nanoribbons and carbon nanotubes are calculated in sizes up to 3 microns, and the relative influence of boundary scattering on thermal transport is determined to be dominant at sizes less than 1 micron, after which the thermal transport largely depends on the quality of the nanostructure interface. The method is also extended to carbon nanostructures (fullerenes) where phonon confinement, as opposed to boundary scattering, dominates, and general trends related to the influence of curvature on thermal transport in these materials are discussed.

  3. Measurement of temperature-dependent viscosity and thermal conductivity of alumina and titania thermal oil nanofluids

    Science.gov (United States)

    Cieśliński, Janusz T.; Ronewicz, Katarzyna; Smoleń, Sławomir

    2015-12-01

    In this study the results of simultaneous measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of two nanofluids, i.e., thermal oil/Al2O3 and thermal oil/TiO2 are presented. Thermal oil is selected as a base liquid because of possible application in ORC systems as an intermediate heating agent. Nanoparticles were tested at the concentration of 0.1%, 1%, and 5% by weight within temperature range from 20 °C to 60 °C. Measurement devices were carefully calibrated by comparison obtained results for pure base liquid (thermal oil) with manufacturer's data. The results obtained for tested nanofluids were compared with predictions made by use of existing models for liquid/solid particles mixtures.

  4. Measurement of temperature-dependent viscosity and thermal conductivity of alumina and titania thermal oil nanofluids

    Directory of Open Access Journals (Sweden)

    Cieśliński Janusz T.

    2015-12-01

    Full Text Available In this study the results of simultaneous measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of two nanofluids, i.e., thermal oil/Al2O3 and thermal oil/TiO2 are presented. Thermal oil is selected as a base liquid because of possible application in ORC systems as an intermediate heating agent. Nanoparticles were tested at the concentration of 0.1%, 1%, and 5% by weight within temperature range from 20 °C to 60 °C. Measurement devices were carefully calibrated by comparison obtained results for pure base liquid (thermal oil with manufacturer’s data. The results obtained for tested nanofluids were compared with predictions made by use of existing models for liquid/solid particles mixtures.

  5. Thermal Transport in Graphene Oxide – From Ballistic Extreme to Amorphous Limit

    Science.gov (United States)

    Mu, Xin; Wu, Xufei; Zhang, Teng; Go, David B.; Luo, Tengfei

    2014-01-01

    Graphene oxide is being used in energy, optical, electronic and sensor devices due to its unique properties. However, unlike its counterpart – graphene – the thermal transport properties of graphene oxide remain unknown. In this work, we use large-scale molecular dynamics simulations with reactive potentials to systematically study the role of oxygen adatoms on the thermal transport in graphene oxide. For pristine graphene, highly ballistic thermal transport is observed. As the oxygen coverage increases, the thermal conductivity is significantly reduced. An oxygen coverage of 5% can reduce the graphene thermal conductivity by ~90% and a coverage of 20% lower it to ~8.8 W/mK. This value is even lower than the calculated amorphous limit (~11.6 W/mK for graphene), which is usually regarded as the minimal possible thermal conductivity of a solid. Analyses show that the large reduction in thermal conductivity is due to the significantly enhanced phonon scattering induced by the oxygen defects which introduce dramatic structural deformations. These results provide important insight to the thermal transport physics in graphene oxide and offer valuable information for the design of graphene oxide-based materials and devices. PMID:24468660

  6. Squeezed Thermal Reservoirs as a Resource for a Nanomechanical Engine beyond the Carnot Limit

    Directory of Open Access Journals (Sweden)

    Jan Klaers

    2017-09-01

    Full Text Available The efficient conversion of thermal energy to mechanical work by a heat engine is an ongoing technological challenge. Since the pioneering work of Carnot, it has been known that the efficiency of heat engines is bounded by a fundamental upper limit—the Carnot limit. Theoretical studies suggest that heat engines may be operated beyond the Carnot limit by exploiting stationary, nonequilibrium reservoirs that are characterized by a temperature as well as further parameters. In a proof-of-principle experiment, we demonstrate that the efficiency of a nanobeam heat engine coupled to squeezed thermal noise is not bounded by the standard Carnot limit. Remarkably, we also show that it is possible to design a cyclic process that allows for extraction of mechanical work from a single squeezed thermal reservoir. Our results demonstrate a qualitatively new regime of nonequilibrium thermodynamics at small scales and provide a new perspective on the design of efficient, highly miniaturized engines.

  7. Squeezed Thermal Reservoirs as a Resource for a Nanomechanical Engine beyond the Carnot Limit

    Science.gov (United States)

    Klaers, Jan; Faelt, Stefan; Imamoglu, Atac; Togan, Emre

    2017-07-01

    The efficient conversion of thermal energy to mechanical work by a heat engine is an ongoing technological challenge. Since the pioneering work of Carnot, it has been known that the efficiency of heat engines is bounded by a fundamental upper limit—the Carnot limit. Theoretical studies suggest that heat engines may be operated beyond the Carnot limit by exploiting stationary, nonequilibrium reservoirs that are characterized by a temperature as well as further parameters. In a proof-of-principle experiment, we demonstrate that the efficiency of a nanobeam heat engine coupled to squeezed thermal noise is not bounded by the standard Carnot limit. Remarkably, we also show that it is possible to design a cyclic process that allows for extraction of mechanical work from a single squeezed thermal reservoir. Our results demonstrate a qualitatively new regime of nonequilibrium thermodynamics at small scales and provide a new perspective on the design of efficient, highly miniaturized engines.

  8. Linking biogeography to physiology: Evolutionary and acclimatory adjustments of thermal limits

    Directory of Open Access Journals (Sweden)

    Somero George N

    2005-01-01

    Full Text Available Abstract Temperature-adaptive physiological variation plays important roles in latitudinal biogeographic patterning and in setting vertical distributions along subtidal-to-intertidal gradients in coastal marine ecosystems. Comparisons of congeneric marine invertebrates reveal that the most warm-adapted species may live closer to their thermal tolerance limits and have lower abilities to increase heat tolerance through acclimation than more cold-adapted species. In crabs and snails, heart function may be of critical importance in establishing thermal tolerance limits. Temperature-mediated shifts in gene expression may be critical in thermal acclimation. Transcriptional changes, monitored using cDNA microarrays, have been shown to differ between steady-state thermal acclimation and diurnal temperature cycling in a eurythermal teleost fish (Austrofundulus limnaeus. In stenothermal Antarctic notothenioid fish, losses in capacity for temperature-mediated gene expression, including the absence of a heat-shock response, may reduce the abilities of these species to acclimate to increased temperatures. Differences among species in thermal tolerance limits and in the capacities to adjust these limits may determine how organisms are affected by climate change.

  9. The defect level and ideal thermal conductivity of graphene uncovered by residual thermal reffusivity at the 0 K limit.

    Science.gov (United States)

    Xie, Yangsu; Xu, Zaoli; Xu, Shen; Cheng, Zhe; Hashemi, Nastaran; Deng, Cheng; Wang, Xinwei

    2015-06-14

    Due to its intriguing thermal and electrical properties, graphene has been widely studied for potential applications in sensor and energy devices. However, the reported value for its thermal conductivity spans from dozens to thousands of W m(-1) K(-1) due to different levels of alternations and defects in graphene samples. In this work, the thermal diffusivity of suspended four-layered graphene foam (GF) is characterized from room temperature (RT) down to 17 K. For the first time, we identify the defect level in graphene by evaluating the inverse of thermal diffusivity (termed "thermal reffusivity": Θ) at the 0 K limit. By using the Debye model of Θ = Θ0 + C× e(-θ/2T) and fitting the Θ-T curve to the point of T = 0 K, we identify the defect level (Θ0) and determine the Debye temperature of graphene. Θ0 is found to be 1878 s m(-2) for the studied GF and 43-112 s m(-2) for three highly crystalline graphite materials. This uncovers a 16-43-fold higher defect level in GF than that in pyrolytic graphite. In GF, the phonon mean free path solely induced by defects and boundary scattering is determined as 166 nm. The Debye temperature of graphene is determined to be 1813 K, which is very close to the average theoretical Debye temperature (1911 K) of the three acoustic phonon modes in graphene. By subtracting the defect effect, we report the ideal thermal diffusivity and conductivity (κideal) of graphene presented in the 3D foam structure in the range of 33-299 K. Detailed physics based on chemical composition and structure analysis are given to explain the κideal-T profile by comparing with those reported for suspended graphene.

  10. Effects of nanoscale size dependent parameters on lattice thermal ...

    Indian Academy of Sciences (India)

    The obtained fitting value for mean Gruneisen parameter has a systematic dependence on all Si nanowire diameters changing from 0·791 for 115 nm diameter to 1·515 for the 22 nm nanowire diameter. The dependence also gave a suggested surface thickness of about 5–6 nm. The other two parameters were found to have ...

  11. A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations

    DEFF Research Database (Denmark)

    Wu, Rui; Wang, Huai; Ma, Ke

    2014-01-01

    Thermal impedance of IGBT modules may vary with operating conditions due to that the thermal conductivity and heat capacity of materials are temperature dependent. This paper proposes a Cauer thermal model for a 1700 V/1000 A IGBT module with temperature-dependent thermal resistances and thermal...... relevant reliability aspect performance. A test bench is built up with an ultra-fast infrared (IR) camera to validate the proposed thermal impedance model....... capacitances. The temperature effect is investigated by Finite Element Method (FEM) simulation based on the geometry and material information of the IGBT module. The developed model is ready for circuit-level simulation to achieve an improved accuracy of the estimation on IGBT junction temperature and its...

  12. Rate limit of protein elastic response is tether dependent

    Science.gov (United States)

    Berkovich, Ronen; Hermans, Rodolfo I.; Popa, Ionel; Stirnemann, Guillaume; Garcia-Manyes, Sergi; Berne, Bruce J.; Fernandez, Julio M.

    2012-01-01

    The elastic restoring force of tissues must be able to operate over the very wide range of loading rates experienced by living organisms. It is surprising that even the fastest events involving animal muscle tissues do not surpass a few hundred hertz. We propose that this limit is set in part by the elastic dynamics of tethered proteins extending and relaxing under a changing load. Here we study the elastic dynamics of tethered proteins using a fast force spectrometer with sub-millisecond time resolution, combined with Brownian and Molecular Dynamics simulations. We show that the act of tethering a polypeptide to an object, an inseparable part of protein elasticity in vivo and in experimental setups, greatly reduces the attempt frequency with which the protein samples its free energy. Indeed, our data shows that a tethered polypeptide can traverse its free-energy landscape with a surprisingly low effective diffusion coefficient Deff ∼ 1,200 nm2/s. By contrast, our Molecular Dynamics simulations show that diffusion of an isolated protein under force occurs at Deff ∼ 108 nm2/s. This discrepancy is attributed to the drag force caused by the tethering object. From the physiological time scales of tissue elasticity, we calculate that tethered elastic proteins equilibrate in vivo with Deff ∼ 104–106 nm2/s which is two to four orders magnitude smaller than the values measured for untethered proteins in bulk. PMID:22895787

  13. Effects of temperature dependence of electrical and thermal conductivities on the heating of a one dimensional conductor

    Science.gov (United States)

    Antoulinakis, Foivos; Zhang, Peng; Lau, Y. Y.; Chernin, David

    2016-10-01

    Dependence of electrical conductivity on temperature gives rise to electrotheramal instability, an important instability for Z-pinches. In other areas, ohmic heating limits the operation of nanoscale circuits such as graphene electronics, carbon nanofiber based field emitters, and nanolasers. For many applications, it is important to consider the temperature dependence of the thermal and electrical conductivities when calculating the effects of ohmic heating. We examine the effects of linear temperature dependence of the electrical and thermal conductivities on the heating of a one-dimensional conductor by solving the coupled non-linear steady state electrical and thermal conduction equations. We find that there are conditions under which no steady state solution exists. In the special case in which the temperature dependence of the electrical conductivity may be neglected, we have obtained explicit expressions for these conditions. The maximum temperature and its location within the conductor are examined for various boundary conditions. We note that the absence of a steady state solution may indicate the possibility of thermal runaway. Work supported by AFOSR No. FA9550-14-1-0309, and by L-3 Communications.

  14. Conserved and narrow temperature limits in alpine insects: Thermal tolerance and supercooling points of the ice-crawlers, Grylloblatta (Insecta: Grylloblattodea: Grylloblattidae).

    Science.gov (United States)

    Schoville, Sean D; Slatyer, Rachel A; Bergdahl, James C; Valdez, Glenda A

    2015-07-01

    For many terrestrial species, habitat associations and range size are dependent on physiological limits, which in turn may influence large-scale patterns of species diversity. The temperature range experienced by individuals is considered to shape the breadth of the thermal niche, with species occupying temporally and/or geographically stable climates tolerating a narrow temperature range. High-elevation environments experience large temperature fluctuations, with frequent periods below 0 °C, but Grylloblatta (Grylloblattodea: Grylloblattidae) occupy climatically stable microhabitats within this region. Here we test critical thermal limits and supercooling points for five Grylloblatta populations from across a large geographic area, to examine whether the stable microhabitats of this group are associated with a narrow thermal niche and assess their capacity to tolerate cold conditions. Thermal limits are highly conserved in Grylloblatta, despite substantial genetic divergence among populations spanning 1500 m elevation and being separated by over 500 km. Further, Grylloblatta show exceptionally narrow thermal limits compared to other insect taxa with little capacity to improve cold tolerance via plasticity. In contrast, upper thermal limits were significantly depressed by cold acclimation. Grylloblatta maintain coordinated movement until they freeze, and they die upon freezing. Convergence of the critical thermal minima, supercooling point and lower lethal limits point to adaptation to a cold but, importantly, constant thermal environment. These physiological data provide an explanation for the high endemism and patchy distribution of Grylloblatta, which relies on subterranean retreats to accommodate narrow thermal limits. These retreats are currently buffered from temperature fluctuations by snow cover, and a declining snowpack thus places Grylloblatta at risk of exposure to temperatures beyond its tolerance capacity. Copyright © 2015 Elsevier Ltd. All rights

  15. Thermal Performance Testing of Order Dependancy of Aerogels Multilayered Insulation

    Science.gov (United States)

    Johnson, Wesley L.; Fesmire, James E.; Demko, J. A.

    2009-01-01

    Robust multilayer insulation systems have long been a goal of many research projects. Such insulation systems must provide some degree of structural support and also mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MU) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel and multilayer insulation systems have been tested at Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MU and aerogel blankets. Apparent thermal conductivity testing under cryogenic-vacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.

  16. Thermal limitation of performance and biogeography in a free-ranging ectotherm: insights from accelerometry.

    Science.gov (United States)

    Gannon, Ruan; Taylor, Matthew D; Suthers, Iain M; Gray, Charles A; van der Meulen, Dylan E; Smith, James A; Payne, Nicholas L

    2014-09-01

    Theoretical and laboratory studies generally show that ectotherm performance increases with temperature to an optimum, and subsequently declines. Several physiological mechanisms probably shape thermal performance curves, but responses of free-ranging animals to temperature variation will represent a compromise between these mechanisms and ecological constraints. Thermal performance data from wild animals balancing physiology and ecology are rare, and this represents a hindrance for predicting population impacts of future temperature change. We used internally implanted accelerometers near the middle of a species' geographical distribution and gill-net catch data near the species' latitudinal extremes to quantify temperature-related activity levels of a wild predatory fish (Platycephalus fuscus). We examined our data in the context of established models of thermal performance, and the relationship between thermal performance thresholds and biogeography. Acceleration data approximated a thermal performance curve, with activity peaking at 23°C but declining rapidly at higher temperatures. Gill-net catch data displayed a similar trend, with a temperature-associated increase and decrease in catch rates in temperate and tropical regions, respectively. Extrapolated estimates of zero activity (CTmin and CTmax) from the accelerometers were similar to the minimum and maximum mean monthly water temperatures experienced at the southern and northern (respectively) limits of the species distribution, consistent with performance-limited biogeography in this species. These data highlight the fundamental influence of temperature on ectotherm performance, and how thermal performance limits may shape biogeography. Biologging approaches are rarely used to examine thermal performance curves in free-ranging animals, but these may be central to understanding the trade-offs between physiology and ecology that constrain species' biogeographies and determine the susceptibility of

  17. Oxygen safety margins set thermal limits in an insect model system.

    Science.gov (United States)

    Boardman, Leigh; Terblanche, John S

    2015-06-01

    A mismatch between oxygen availability and metabolic demand may constrain thermal tolerance. While considerable support for this idea has been found in marine organisms, results from insects are equivocal and raise the possibility that mode of gas exchange, oxygen safety margins and the physico-chemical properties of the gas medium influence heat tolerance estimates. Here, we examined critical thermal maximum (CTmax) and aerobic scope under altered oxygen supply and in two life stages that varied in metabolic demand in Bombyx mori (Lepidoptera: Bombycidae). We also systematically examined the influence of changes in gas properties on CTmax. Larvae have a lower oxygen safety margin (higher critical oxygen partial pressure at which metabolism is suppressed relative to metabolic demand) and significantly higher CTmax under normoxia than pupae (53°C vs 50°C). Larvae, but not pupae, were oxygen limited with hypoxia (2.5 kPa) decreasing CTmax significantly from 53 to 51°C. Humidifying hypoxic air relieved the oxygen limitation effect on CTmax in larvae, whereas variation in other gas properties did not affect CTmax. Our data suggest that oxygen safety margins set thermal limits in air-breathing invertebrates and the magnitude of this effect potentially reconciles differences in oxygen limitation effects on thermal tolerance found among diverse taxa to date. © 2015. Published by The Company of Biologists Ltd.

  18. A molecular dynamics study of stiffness-dependent thermal conductivity of graphene

    Science.gov (United States)

    Huang, Jianzhang; Han, Qiang

    2017-03-01

    Non-equilibrium molecular dynamics (NEMD) simulations is used to investigate the effect of support stiffness on thermal conductivity property based on the ‘graphene-springs’ model. It shows that the support stiffness greatly influences the thermal conductivity. Thermal conductivity of graphene decreases nonlinearly as the support stiffness increases. The temperature stability of thermal conductivity property of graphene can be improved by the support stiffness. For patterned stiffness supported stripe, thermal conductivity is significantly dependent on the patterned area, angle and stripe distribution. The work in this paper reveals the possibility for designing and controlling of thermal conduction of graphene by using support stiffness, which is beneficial to the application of graphene in nanoscale devices.

  19. Manipulating the temperature dependence of the thermal conductivity of graphene phononic crystal.

    Science.gov (United States)

    Hu, Shiqian; An, Meng; Yang, Nuo; Li, Baowen

    2016-07-01

    By using non-equilibrium molecular dynamics simulations, modulating the temperature dependence of thermal conductivity of graphene phononic crystals (GPnCs) is investigated. It is found that the temperature dependence of thermal conductivity of GPnCs follows ∼T (-α) behavior. The power exponents (α) can be efficiently tuned by changing the characteristic size of GPnCs. The phonon participation ratio spectra and dispersion relation reveal that the long-range phonon modes are more affected in GPnCs with larger holes (L 0). Our results suggest that constructing GPnCs is an effective method to manipulate the temperature dependence of thermal conductivity of graphene, which would be beneficial for developing GPnC-based thermal management and signal processing devices.

  20. Thermal dependence of luminescence lifetimes and radioluminescence in quartz

    Energy Technology Data Exchange (ETDEWEB)

    Pagonis, V., E-mail: vpagonis@mcdaniel.edu [McDaniel College, Physics Department, Westminster, MD 21157 (United States); Chithambo, M.L. [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa); Chen, R. [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Chruścińska, A. [Institute of Physics, Nicholas Copernicus University, 87-100 Toruń (Poland); Fasoli, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Li, S.H. [Department of Earth Sciences, The University of Hong Kong (Hong Kong); Martini, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Ramseyer, K. [Institut für Geologie, Baltzerstrasse 1-3, 3012 Bern (Switzerland)

    2014-01-15

    During time-resolved optical stimulation experiments (TR-OSL), one uses short light pulses to separate the stimulation and emission of luminescence in time. Experimental TR-OSL results show that the luminescence lifetime in quartz of sedimentary origin is independent of annealing temperature below 500 °C, but decreases monotonically thereafter. These results have been interpreted previously empirically on the basis of the existence of two separate luminescence centers L{sub H} and L{sub L} in quartz, each with its own distinct luminescence lifetime. Additional experimental evidence also supports the presence of a non-luminescent hole reservoir R, which plays a critical role in the predose effect in this material. This paper extends a recently published analytical model for thermal quenching in quartz, to include the two luminescence centers L{sub H} and L{sub L}, as well as the hole reservoir R. The new extended model involves localized electronic transitions between energy states within the two luminescence centers, and is described by a system of differential equations based on the Mott–Seitz mechanism of thermal quenching. It is shown that by using simplifying physical assumptions, one can obtain analytical solutions for the intensity of the light during a TR-OSL experiment carried out with previously annealed samples. These analytical expressions are found to be in good agreement with the numerical solutions of the equations. The results from the model are shown to be in quantitative agreement with published experimental data for commercially available quartz samples. Specifically the model describes the variation of the luminescence lifetimes with (a) annealing temperatures between room temperature and 900 °C, and (b) with stimulation temperatures between 20 and 200 °C. This paper also reports new radioluminescence (RL) measurements carried out using the same commercially available quartz samples. Gaussian deconvolution of the RL emission spectra was

  1. Review of thresholds and recommendations for revised exposure limits for laser and optical radiation for thermally induced retinal injury.

    Science.gov (United States)

    Schulmeister, Karl; Stuck, Bruce E; Lund, David J; Sliney, David H

    2011-02-01

    Exposure limits (ELs) for laser and optical broadband radiation that are derived to protect the retina from adverse thermally-induced effects vary as a function of wavelength, exposure duration, and retinal irradiance diameter (spot size) expressed as the angular subtense α. A review of ex vivo injury threshold data shows that, in the ns regime, the microcavitation-induced damage mechanism results in retinal injury thresholds below thermal denaturation-induced thresholds. This appears to be the reason that the injury thresholds for retinal spot sizes of about 80 μm (α = 6 mrad) and pulse durations of about 5 ns in the green wavelength range are very close to current ELs, calling for a reduction of the EL in the ns regime. The ELs, expressed in terms of retinal radiant exposure or radiance dose, currently exhibit a 1/α dependence up to a retinal spot size of 100 mrad, referred to as αmax. For α ≥ αmax, the EL is a constant retinal radiant exposure (no α dependence) for any given exposure duration. Recent ex vivo, computer model, and non-human primate in vivo threshold data provide a more complete assessment of the retinal irradiance diameter dependence for a wide range of exposure durations. The transition of the 1/α dependence to a constant retinal radiant exposure (or constant radiance dose) is not a constant αmax but varies as a function of the exposure duration. The value of αmax of 100 mrad reflects the spot size dependence of the injury thresholds only for longer duration exposures. The injury threshold data suggest that αmax could increase as a function of the exposure duration, starting in the range of 5 mrad in the μs regime, which would increase the EL for pulsed exposure and extended sources by up to a factor of 20, while still assuring an appropriate reduction factor between the injury threshold and the exposure limit.

  2. Metabolomics reveal physiological changes in mayfly larvae (Neocloeon triangulifer) at ecological upper thermal limits.

    Science.gov (United States)

    Chou, Hsuan; Pathmasiri, Wimal; Deese-Spruill, Jocelin; Sumner, Susan; Buchwalter, David B

    2017-08-01

    Aquatic insects play critical roles in freshwater ecosystems and temperature is a fundamental driver of species performance and distributions. However, the physiological mechanisms that determine the thermal performance of species remain unclear. Here we used a metabolomics approach to gain insights into physiological changes associated with a short-term, sublethal thermal challenge in the mayfly Neocloeon triangulifer (Ephemeroptera: Baetidae). Larvae were subjected to a thermal ramp (from 22 to 30°C at a rate of 1°C/h) and metabolomics analysis (both Nuclear Magnetic Resonance (NMR) Spectroscopy and Gas Chromatography coupled Time-of-Flight Mass Spectrometry (GC-TOF-MS)) indicated that processes related to energetics (sugar metabolism) and membrane stabilization primarily differentiated heat treated larvae from controls. Limited evidence of anaerobic metabolism was observed in the heat treated larvae at 30°C, a temperature that is chronically lethal to larvae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Limits to solar power conversion efficiency with applications to quantum and thermal systems

    Science.gov (United States)

    Byvik, C. E.; Buoncristiani, A. M.; Smith, B. T.

    1983-01-01

    An analytical framework is presented that permits examination of the limit to the efficiency of various solar power conversion devices. Thermodynamic limits to solar power efficiency are determined for both quantum and thermal systems, and the results are applied to a variety of devices currently considered for use in space systems. The power conversion efficiency for single-threshold energy quantum systems receiving unconcentrated air mass zero solar radiation is limited to 31 percent. This limit applies to photovoltaic cells directly converting solar radiation, or indirectly, as in the case of a thermophotovoltaic system. Photoelectrochemical cells rely on an additional chemical reaction at the semiconductor-electrolyte interface, which introduces additional second-law demands and a reduction of the solar conversion efficiency. Photochemical systems exhibit even lower possible efficiencies because of their relatively narrow absorption bands. Solar-powered thermal engines in contact with an ambient reservoir at 300 K and operating at maximum power have a peak conversion efficiency of 64 percent, and this occurs for a thermal reservoir at a temperature of 2900 K. The power conversion efficiency of a solar-powered liquid metal magnetohydrodydnamic generator, a solar-powered steam turbine electric generator, and an alkali metal thermoelectric converter is discussed.

  4. Asymptotic diffusion limit of cell temperature discretisation schemes for thermal radiation transport

    Energy Technology Data Exchange (ETDEWEB)

    Smedley-Stevenson, Richard P., E-mail: richard.smedley-stevenson@awe.co.uk [AWE PLC, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Department of Earth Science and Engineering, Imperial College London, SW7 2AZ (United Kingdom); McClarren, Ryan G., E-mail: rmcclarren@ne.tamu.edu [Department of Nuclear Engineering, Texas A & M University, College Station, TX 77843-3133 (United States)

    2015-04-01

    This paper attempts to unify the asymptotic diffusion limit analysis of thermal radiation transport schemes, for a linear-discontinuous representation of the material temperature reconstructed from cell centred temperature unknowns, in a process known as ‘source tilting’. The asymptotic limits of both Monte Carlo (continuous in space) and deterministic approaches (based on linear-discontinuous finite elements) for solving the transport equation are investigated in slab geometry. The resulting discrete diffusion equations are found to have nonphysical terms that are proportional to any cell-edge discontinuity in the temperature representation. Based on this analysis it is possible to design accurate schemes for representing the material temperature, for coupling thermal radiation transport codes to a cell centred representation of internal energy favoured by ALE (arbitrary Lagrange–Eulerian) hydrodynamics schemes.

  5. Bounding the quantum limits of precision for phase estimation with loss and thermal noise

    Science.gov (United States)

    Gagatsos, Christos N.; Bash, Boulat A.; Guha, Saikat; Datta, Animesh

    2017-12-01

    We consider the problem of estimating an unknown but constant carrier phase modulation θ using a general, possibly entangled, n -mode optical probe through n independent and identical uses of a lossy bosonic channel with additive thermal noise. We find an upper bound to the quantum Fisher information (QFI) of estimating θ as a function of n , the mean and variance of the total number of photons NS in the n -mode probe, the transmissivity η , and mean thermal photon number per mode n¯B of the bosonic channel. Since the inverse of QFI provides a lower bound to the mean-square error (MSE) of an unbiased estimator θ ˜ of θ , our upper bound to the QFI provides a lower bound to the MSE. It already has found use in proving fundamental limits of covert sensing and could find other applications requiring bounding the fundamental limits of sensing an unknown parameter embedded in a correlated field.

  6. Simulation of thermal ablation by high-intensity focused ultrasound with temperature-dependent properties.

    Science.gov (United States)

    Huang, C W; Sun, M K; Chen, B T; Shieh, J; Chen, C S; Chen, W S

    2015-11-01

    An integrated computational framework was developed in this study for modeling high-intensity focused ultrasound (HIFU) thermal ablation. The temperature field was obtained by solving the bioheat transfer equation (BHTE) through the finite element method; while, the thermal lesion was considered as a denatured material experiencing phase transformation and modeled with the latent heat. An equivalent attenuation coefficient, which considers the temperature-dependent properties of the target material and the ultrasound diffraction due to bubbles, was proposed in the nonlinear thermal transient analysis. Finally, a modified thermal dose formulation was proposed to predict the lesion size, shape and location. In-vitro thermal ablation experiments on transparent tissue phantoms at different energy levels were carried out to validate this computational framework. The temperature histories and lesion areas from the proposed model show good correlation with those from the in-vitro experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The impact of harmonic distortion on power transformers operating near the thermal limit

    OpenAIRE

    2009-01-01

    M.Ing. The study looks into the impact of harmonic distortion on power-plant equipment in general, and then focuses on the impact it has on power transformers operating near the thermal limit. The feasibility of the study is firstly evaluated and then the theory on harmonics and transformer losses is analysed. The study had been narrowed down to power transformers due to the high numbers of failures nationally and internationally attributed to unknown causes. A transformer model is then de...

  8. Parameter dependent thermal conductivity model for titanium and graphite powder mixture compact

    Energy Technology Data Exchange (ETDEWEB)

    Azad, G.M.S.; Cui, T.; Huque, Z. [Prairie View A and M Univ., Prairie View, TX (United States). Dept. of Mechanical Engineering

    1996-12-31

    Self-Propagating High-Temperature Synthesis (SHS) is an energy-efficient combustion method of producing refractory, ceramic, and composite materials from their constituent powders. To accurately model the SHS process it is important to understand the physical and chemical mechanisms involved in the reaction process along with the effects of various microstructural and physical parameters controlling the process. Physical parameters include the initial temperature of the green compact, thermal conductivity of the compact, density, particle size and mixture ratio of the constituents. Of these parameters, effective thermal conductivity is directly dependent on the initial density, mixing ratio and the particle size of the constituents. Here, the effects of initial density, composition mixture ratio, and particle size on thermal conductivity of titanium and graphite powder mixture compact has been experimentally investigated and a thermal conductivity model has been developed. Thermal conductivity values have been measured for compact densities ranging from 45% to 775 of maximum theoretical density and for Ti/C mixture ratio by weight ranging from 0.7 to 1.3. The model predicts that, for an increase in density, thermal conductivity increases but it decreases with an increase of Ti/C mixture ratio. The experimental results also show the dependence trend of thermal conductivity on particle size of the constituents.

  9. Moisture dependent thermal properties of hydrophilic mineral wool: application of the effective media theory

    Directory of Open Access Journals (Sweden)

    Iñigo Antepara

    2015-09-01

    Full Text Available Thermal properties of mineral wool based materials appear to be of particular importance for their practical applications because the majority of them is used in the form of thermal insulation boards. Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly. Exposure to outside climate or any other environment containing moisture can negatively affect the thermal insulation properties of mineral wool. Nevertheless, the mineral wool materials due to their climatic loading and their environmental exposure contain moisture that can negatively affect their thermal insulation properties. Because the presence of water in mineral wool material is undesirable for the majority of applications, many products are provided with hydrophobic substances. Hydrophilic additives are seldom used in mineral wool products. However, this kind of materials has a good potential for application for instance in interior thermal insulation systems, masonry desalination, green roofs, etc. For these materials, certain moisture content must be estimated and thus their thermal properties will be different than for the dry state. On this account, moisture dependent thermal properties of hydrophilic mineral wool (HMW are studied in a wide range of moisture content using a pulse technique. The experimentally determined thermal conductivity data is analysed using several homogenization formulas based on the effective media theory. In terms of homogenization, a porous material is considered as a mixture of two or three phases. In case of dry state, material consists from solid and gaseous phase. When moistened, liquid phase is also present. Mineral wool consists of the solid phase represented by basalt fibers, the liquid phase by water and the gaseous phase by air. At first, the homogenization techniques are applied for the

  10. Studies of thermal energy confinement scaling in PDX plasmas: D/sup 0/. -->. H/sup +/ limiter discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kaye, S.M.; Goldston, R.J.; Bell, M.; Bol, K.; Bitter, M.; Fonck, R.; Grek, B.; Hawryluk, R.J.; Johnson, D.; Kaita, R.

    1984-06-01

    Experiments were performed on the PDX tokamak to study plasma heating and ..beta.. scaling with higher power, near-perpendicular neutral beam injection. The data taken during these experiments were analyzed using a time-dependent data interpretation code (TRANSP) to study the transport and thermal confinement scaling over a wide range of plasma parameters. This study focuses on results from experiments with D/sup 0/ injection into H/sup +/ plasmas using graphite rail limiters, a = 40 to 44 cm, R = 143 cm, I/sub p/ = 200 to 480 kA, B/sub T/ = 0.7 to 2.2 T, and typically anti n/sub e/ = 2.5 to 4.2 x 10/sup 13/ cm/sup -3/. The results of this study indicate that for both ohmic and neutral beam heated discharges the energy flow out of the plasma is dominated by anomalous electron losses, attributed to electron thermal conduction. The ion conduction losses are well described to electron thermal conduction. The ion conduction losses are well described by neoclassical theory; however, the total ion loss influences the power balance significantly only at high toroidal fields and high plasma currents.

  11. Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

    Science.gov (United States)

    Gunderson, Alex R.; Stillman, Jonathon H.

    2015-01-01

    Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater and marine habitats. Contrary to expectation, plasticity in heat tolerance was unrelated to latitude or thermal seasonality. However, plasticity in cold tolerance is associated with thermal seasonality in some habitat types. In addition, aquatic taxa have approximately twice the plasticity of terrestrial taxa. Based on the observed patterns of variation in tolerance plasticity, we propose that limited potential for behavioural plasticity (i.e. behavioural thermoregulation) favours the evolution of greater plasticity in physiological traits, consistent with the ‘Bogert effect’. Finally, we find that all ectotherms have relatively low acclimation in thermal tolerance and demonstrate that overheating risk will be minimally reduced by acclimation in even the most plastic groups. Our analysis indicates that behavioural and evolutionary mechanisms will be critical in allowing ectotherms to buffer themselves from extreme temperatures. PMID:25994676

  12. Thermal limit for metazoan life in question: in vivo heat tolerance of the Pompeii worm.

    Science.gov (United States)

    Ravaux, Juliette; Hamel, Gérard; Zbinden, Magali; Tasiemski, Aurélie A; Boutet, Isabelle; Léger, Nelly; Tanguy, Arnaud; Jollivet, Didier; Shillito, Bruce

    2013-01-01

    The thermal limit for metazoan life, expected to be around 50°C, has been debated since the discovery of the Pompeii worm Alvinella pompejana, which colonizes black smoker chimney walls at deep-sea vents. While indirect evidence predicts body temperatures lower than 50°C, repeated in situ temperature measurements depict an animal thriving at temperatures of 60°C and more. This controversy was to remain as long as this species escaped in vivo investigations, due to irremediable mortalities upon non-isobaric sampling. Here we report from the first heat-exposure experiments with live A. pompejana, following isobaric sampling and subsequent transfer in a laboratory pressurized aquarium. A prolonged (2 hours) exposure in the 50-55°C range was lethal, inducing severe tissue damages, cell mortalities and triggering a heat stress response, therefore showing that Alvinella's upper thermal limit clearly is below 55°C. A comparison with hsp70 stress gene expressions of individuals analysed directly after sampling in situ confirms that Alvinella pompejana does not experience long-term exposures to temperature above 50°C in its natural environment. The thermal optimum is nevertheless beyond 42°C, which confirms that the Pompeii worm ranks among the most thermotolerant metazoans.

  13. Thermal limit for metazoan life in question: in vivo heat tolerance of the Pompeii worm.

    Directory of Open Access Journals (Sweden)

    Juliette Ravaux

    Full Text Available The thermal limit for metazoan life, expected to be around 50°C, has been debated since the discovery of the Pompeii worm Alvinella pompejana, which colonizes black smoker chimney walls at deep-sea vents. While indirect evidence predicts body temperatures lower than 50°C, repeated in situ temperature measurements depict an animal thriving at temperatures of 60°C and more. This controversy was to remain as long as this species escaped in vivo investigations, due to irremediable mortalities upon non-isobaric sampling. Here we report from the first heat-exposure experiments with live A. pompejana, following isobaric sampling and subsequent transfer in a laboratory pressurized aquarium. A prolonged (2 hours exposure in the 50-55°C range was lethal, inducing severe tissue damages, cell mortalities and triggering a heat stress response, therefore showing that Alvinella's upper thermal limit clearly is below 55°C. A comparison with hsp70 stress gene expressions of individuals analysed directly after sampling in situ confirms that Alvinella pompejana does not experience long-term exposures to temperature above 50°C in its natural environment. The thermal optimum is nevertheless beyond 42°C, which confirms that the Pompeii worm ranks among the most thermotolerant metazoans.

  14. Size and edge roughness dependence of thermal conductivity for vacancy-defective graphene ribbons.

    Science.gov (United States)

    Xie, Guofeng; Shen, Yulu

    2015-04-14

    By incorporating the phonon-phonon scattering, phonon-boundary scattering and phonon-vacancy scattering into the linearized Boltzmann transport equation, we theoretically investigate the effects of size and edge roughness on thermal conductivity of single vacancy-defective graphene ribbons. Due to the severe suppression of high-frequency phonons by phonon-vacancy scattering which includes the impacts of missing mass and linkages, as well as the variation of the force constant of bonds associated with vacancies, the low-frequency ballistic phonons have a higher contribution to the thermal conductivity, which results in the stronger length, weaker width and weaker edge roughness dependence on thermal conductivity of vacancy-defective graphene ribbons than that of pristine ones. Our findings are helpful to understand and manipulate thermal conductivity of graphene by phononic engineering.

  15. On the linear dependence of a carbon nanofiber thermal conductivity on wall thickness

    Directory of Open Access Journals (Sweden)

    Alexandros Askounis

    2016-11-01

    Full Text Available Thermal transport in carbon nanofibers (CNFs was thoroughly investigated. In particular, individual CNFs were suspended on T-type heat nanosensors and their thermal conductivity was measured over a range of temperatures. Unexpectedly, thermal conductivity was found to be dependent on CNF wall thickness and ranging between ca. 28 and 43 W/(m⋅K. Further investigation of the CNF walls with high resolution electron microscopy allowed us to propose a tentative description of how wall structure affects phonon heat transport inside CNFs. The lower thermal conductivities, compared to other CNTs, was attributed to unique CNF wall structure. Additionally, wall thickness is related to the conducting lattice length of each constituent graphene cone and comparable to the Umklapp length. Hence, as the wall thickness and thus lattice length increases there is a higher probability for phonon scattering to the next layer.

  16. Projecting range limits with coupled thermal tolerance - climate change models: an example based on gray snapper (Lutjanus griseus along the U.S. east coast.

    Directory of Open Access Journals (Sweden)

    Jonathan A Hare

    Full Text Available We couple a species range limit hypothesis with the output of an ensemble of general circulation models to project the poleward range limit of gray snapper. Using laboratory-derived thermal limits and statistical downscaling from IPCC AR4 general circulation models, we project that gray snapper will shift northwards; the magnitude of this shift is dependent on the magnitude of climate change. We also evaluate the uncertainty in our projection and find that statistical uncertainty associated with the experimentally-derived thermal limits is the largest contributor (∼ 65% to overall quantified uncertainty. This finding argues for more experimental work aimed at understanding and parameterizing the effects of climate change and variability on marine species.

  17. Analysis of convective longitudinal fin with temperature-dependent thermal conductivity and internal heat generation

    Directory of Open Access Journals (Sweden)

    M.G. Sobamowo

    2017-03-01

    Full Text Available In this study, analysis of heat transfer in a longitudinal rectangular fin with temperature-dependent thermal conductivity and internal heat generation was carried out using finite difference method. The developed systems of non-linear equations that resulted from the discretization using finite difference scheme were solved with the aid of MATLAB using fsolve. The numerical solution was validated with the exact solution for the linear problem. The developed heat transfer models were used to investigate the effects of thermo-geometric parameters, coefficient of heat transfer and thermal conductivity (non-linear parameters on the temperature distribution, heat transfer and thermal performance of the longitudinal rectangular fin. From the results, it shows that the fin temperature distribution, the total heat transfer, and the fin efficiency are significantly affected by the thermo-geometric parameters of the fin. Also, for the solution to be thermally stable, the fin thermo-geometric parameter must not exceed a specific value. However, it was established that the increase in temperature-dependent properties and internal heat generation values increases the thermal stability range of the thermo-geometric parameter. The results obtained in this analysis serve as basis for comparison of any other method of analysis of the problem.

  18. An Update on the Non-Mass-Dependent Isotope Fractionation under Thermal Gradient

    Science.gov (United States)

    Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard; Liu, Yun

    2013-01-01

    Mass flow and compositional gradient (elemental and isotope separation) occurs when flu-id(s) or gas(es) in an enclosure is subjected to a thermal gradient, and the phenomenon is named thermal diffusion. Gas phase thermal diffusion has been theoretically and experimentally studied for more than a century, although there has not been a satisfactory theory to date. Nevertheless, for isotopic system, the Chapman-Enskog theory predicts that the mass difference is the only term in the thermal diffusion separation factors that differs one isotope pair to another,with the assumptions that the molecules are spherical and systematic (monoatomic-like structure) and the particle collision is elastic. Our previous report indicates factors may be playing a role because the Non-Mass Dependent (NMD) effect is found for both symmetric and asymmetric, linear and spherical polyatomic molecules over a wide range of temperature (-196C to +237C). The observed NMD phenomenon in the simple thermal-diffusion experiments demands quantitative validation and theoretical explanation. Besides the pressure and temperature dependency illustrated in our previous reports, efforts are made in this study to address issues such as the role of convection or molecular structure and whether it is a transient, non-equilibrium effect only.

  19. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence

    Science.gov (United States)

    Flynn, Padrig B.; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P.; Elliott, Christopher T.; Laverty, Garry; Gorman, Sean P.; Graham, William G.; Gilmore, Brendan F.

    2016-01-01

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30–60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa. PMID:27242335

  20. Thermal diffusivity and adiabatic limit temperature characterization of consolidate granular expanded perlite using the flash method

    Science.gov (United States)

    Raefat, Saad; Garoum, Mohammed; Laaroussi, Najma; Thiam, Macodou; Amarray, Khaoula

    2017-07-01

    In this work experimental investigation of apparent thermal diffusivity and adiabatic limit temperature of expanded granular perlite mixes has been made using the flash technic. Perlite granulates were sieved to produce essentially three characteristic grain sizes. The consolidated samples were manufactured by mixing controlled proportions of the plaster and water. The effect of the particle size on the diffusivity was examined. The inverse estimation of the diffusivity and the adiabatic limit temperature at the rear face as well as the heat losses coefficients were performed using several numerical global minimization procedures. The function to be minimized is the quadratic distance between the experimental temperature rise at the rear face and the analytical model derived from the one dimension heat conduction. It is shown that, for all granulometry tested, the estimated parameters lead to a good agreement between the mathematical model and experimental data.

  1. Analysis of the temperature dependence of the thermal conductivity of insulating single crystal oxides

    Directory of Open Access Journals (Sweden)

    E. Langenberg

    2016-10-01

    Full Text Available The temperature dependence of the thermal conductivity of 27 different single crystal oxides is reported from ≈20 K to 350 K. These crystals have been selected among the most common substrates for growing epitaxial thin-film oxides, spanning over a range of lattice parameters from ≈3.7 Å to ≈12.5 Å. Different contributions to the phonon relaxation time are discussed on the basis of the Debye model. This work provides a database for the selection of appropriate substrates for thin-film growth according to their desired thermal properties, for applications in which heat management is important.

  2. THE INFLUENCE OF PRESSURE-DEPENDENT VISCOSITY ON THE THERMAL EVOLUTION OF SUPER-EARTHS

    Energy Technology Data Exchange (ETDEWEB)

    Stamenkovic, Vlada; Noack, Lena; Spohn, Tilman [Institute of Planetology, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Breuer, Doris, E-mail: Vlada.Stamenkovic@dlr.de, E-mail: Lena.Noack@dlr.de, E-mail: Doris.Breuer@dlr.de, E-mail: Tilman.Spohn@dlr.de [Institute of Planetary Research, German Aerospace Center DLR, Rutherfordstrasse 2, 12489 Berlin (Germany)

    2012-03-20

    We study the thermal evolution of super-Earths with a one-dimensional (1D) parameterized convection model that has been adopted to account for a strong pressure dependence of the viscosity. A comparison with a 2D spherical convection model shows that the derived parameterization satisfactorily represents the main characteristics of the thermal evolution of massive rocky planets. We find that the pressure dependence of the viscosity strongly influences the thermal evolution of super-Earths-resulting in a highly sluggish convection regime in the lower mantles of those planets. Depending on the effective activation volume and for cooler initial conditions, we observe with growing planetary mass even the formation of a conductive lid above the core-mantle boundary (CMB), a so-called CMB-lid. For initially molten planets our results suggest no CMB-lids but instead a hot lower mantle and core as well as sluggish lower mantle convection. This implies that the initial interior temperatures, especially in the lower mantle, become crucial for the thermal evolution-the thermostat effect suggested to regulate the interior temperatures in terrestrial planets does not work for massive planets if the viscosity is strongly pressure dependent. The sluggish convection and the potential formation of the CMB-lid reduce the convective vigor throughout the mantle, thereby affecting convective stresses, lithospheric thicknesses, and heat fluxes. The pressure dependence of the viscosity may therefore also strongly affect the propensity of plate tectonics, volcanic activity, and the generation of a magnetic field of super-Earths.

  3. Analyzing Density Operator in Thermal State for Complicated Time-Dependent Optical Systems

    Directory of Open Access Journals (Sweden)

    Jeong Ryeol Choi

    2014-01-01

    Full Text Available Density operator of oscillatory optical systems with time-dependent parameters is analyzed. In this case, a system is described by a time-dependent Hamiltonian. Invariant operator theory is introduced in order to describe time-varying behavior of the system. Due to the time dependence of parameters, the frequency of oscillation, so-called a modified frequency of the system, is somewhat different from the natural frequency. In general, density operator of a time-dependent optical system is represented in terms of the modified frequency. We showed how to determine density operator of complicated time-dependent optical systems in thermal state. Usually, density operator description of quantum states is more general than the one described in terms of the state vector.

  4. Compendium of energy-dependent sensitivity profiles for the TRX-2 thermal lattice

    Energy Technology Data Exchange (ETDEWEB)

    Tomlinson, E.T.; Lucius, J.L.; Drischler, J.D.

    1978-03-01

    Energy-dependent sensitivity profiles for five responses calculated for the TRX-2 thermal lattice with the ORNL sensitivity code system FORSS are presented here both in graphical form and in SENPRO format. The responses are the multiplication factor, k/sub eff/; the ratio of epithermal-to-thermal captures in /sup 238/U, /sup 28/rho; the ratio of epithermal-to-thermal fissions in /sup 235/U, /sup 25/delta; the ratio of fissions in /sup 238/U to fissions in /sup 235/U, /sup 28/delta; and the ratio of captures in /sup 238/U to fissions in /sup 235/U, CR. A summary table of the total sensitivities is also presented.

  5. Pressure-dependence of the phase transitions and thermal expansion in zirconium and hafnium pyrovanadate

    Energy Technology Data Exchange (ETDEWEB)

    Gallington, Leighanne C.; Hester, Brett R.; Kaplan, Benjamin S.; Wilkinson, Angus P. (GIT)

    2017-05-01

    Low or negative thermal expansion (NTE) has been previously observed in members of the ZrP2O7 family at temperatures higher than their order-disorder phase transitions. The thermoelastic properties and phase behavior of the low temperature superstructure and high temperature negative thermal expansion phases of ZrV2O7 and HfV2O7 were explored via in situ variable temperature/pressure powder x-ray diffraction measurements. The phase transition temperatures of ZrV2O7 and HfV2O7 exhibited a very strong dependence on pressure (~700 K GPa), with moderate compression suppressing the formation of their NTE phases below 513 K. Compression also reduced the magnitude of the coefficients of thermal expansion in both the positive and negative thermal expansion phases. Additionally, the high temperature NTE phase of ZrV2O7 was found to be twice as stiff as the low temperature positive thermal expansion superstructure (24 and 12 GPa respectively).

  6. Carbon uptake in low dissolved inorganic carbon environments: the effect of limited carbon availability on photosynthetic organisms in thermal waters

    Science.gov (United States)

    Myers, K. D.; Omelon, C. R.; Bennett, P.

    2010-12-01

    Photosynthesis is the primary carbon fixation process in thermal waters below 70°C, but some hydrothermal waters have extremely low dissolved inorganic carbon (DIC), potentially limiting the growth of inorganic carbon fixing organisms such as algae and cyanobacteria. To address the issue of how carbon is assimilated by phototrophs in these environments, we conducted experiments to compare inorganic carbon uptake mechanisms by two phylogenetically distinct organisms collected from geographically distinct carbon limited systems: the neutral pH geothermal waters of El Tatio, Chile, and the acidic geothermal waters of Tantalus Creek in Norris Geyser Basin, Yellowstone National Park. Discharge waters at El Tatio have low total DIC concentrations (2 to 6 ppm) found mainly as HCO3-; this is in contrast to even lower measured DIC values in Tantalus Creek (as low as 0.13 ppm) that, due to a measured pH of 2.5, exists primarily as CO2. Cyanobacteria and algae are innately physiologically plastic, and we are looking to explore the possibility that carbon limitation in these environments is extreme enough to challenge that plasticity and lead to a suite of carbon uptake adaptations. We hypothesize that these microorganisms utilize adaptive modes of Ci uptake that allow them to survive under these limiting conditions. Cyanobacteria (primarily Synechococcus spp.) isolated from El Tatio can utilize either passive CO2 uptake or active HCO3- uptake mechanisms, in contrast to the eukaryotic alga Cyanidium spp. from Tantalus Creek, which is restricted to an energy-dependent CO2 uptake mechanism. To test this hypothesis, we conducted pH drift experiments (Omelon et al., 2008) to examine changes in pH and [DIC] under a range of pH and [DIC] culture conditions. This work provides baseline information upon which we will begin to investigate the effects of low [DIC] on the growth of phototrophs collected from these and other less carbon limited systems.

  7. Galactic Latitude Dependence of Near-infrared Diffuse Galactic Light: Thermal Emission or Scattered Light?

    Science.gov (United States)

    Sano, K.; Matsuura, S.

    2017-11-01

    Near-infrared (IR) diffuse Galactic light (DGL) consists of scattered light and thermal emission from interstellar dust grains illuminated by the interstellar radiation field (ISRF). At 1.25 and 2.2 μ {{m}}, a recent observational study shows that intensity ratios of the DGL to interstellar 100 μ {{m}} dust emission steeply decrease toward high Galactic latitudes (b). In this paper, we investigate the origin(s) of the b-dependence on the basis of models of thermal emission and scattered light. Combining a thermal emission model with the regional variation of the polycyclic aromatic hydrocarbon abundance observed with Planck, we show that the contribution of the near-IR thermal emission component to the observed DGL is lower than ∼ 20 % . We also examine the b-dependence of the scattered light, assuming a plane–parallel Galaxy with smooth distributions of the ISRF and dust density along the vertical direction, and assuming a scattering phase function according to a recently developed model of interstellar dust. We normalize the scattered light intensity to the 100 μ {{m}} intensity corrected for deviation from the cosecant-b law according to the Planck observation. As the result, the present model that considers the b-dependence of dust and the ISRF properties can account for the observed b-dependence of the near-IR DGL. However, the uncertainty in the correction for the 100 μ {{m}} emission is large, and other normalizing quantities may be appropriate for a more robust analysis of the DGL.

  8. Researches regarding the optimization of thermal treatment depending on hardness for maraging 300 steel

    Directory of Open Access Journals (Sweden)

    A. Nioaţă

    2013-04-01

    Full Text Available The paper presents researches regarding the optimization of aging thermal treatment and solution heat treatment for MARAGING 300, in order to get a certain hardness value. Experimental data processing resulted from the study of MARAGING 300 steel hardness dependence on the temperature and aging maintenance time and solution heat treatment was made using Statistica program. Results have allowed to determine some mathematic patterns for determining heating temperature, maintenance time respectively in order to get a certain steel hardness.

  9. Thermally Activated Contact Strengthening Explains Nonmonotonic Temperature and Velocity Dependence of Atomic Friction

    Directory of Open Access Journals (Sweden)

    Mykhaylo Evstigneev

    2013-11-01

    Full Text Available While the well-established Prandtl-Tomlinson (PT model of atomic friction predicts that the friction force decreases with temperature and grows with velocity, several recent experiments reported that a nonmonotonic temperature dependence and a decreasing velocity dependence may also occur. We propose a minimal extension of the PT model, incorporating the possibility of thermally activated contact strengthening and providing one common framework to quantitatively explain all those “anomalous” experimental findings, as well as the previously known “normal” (PT-like behavior.

  10. Psychosocial difficulties in alcohol dependence: a systematic review of activity limitations and participation restrictions.

    Science.gov (United States)

    Levola, Jonna; Kaskela, Teemu; Holopainen, Antti; Sabariego, Carla; Tourunen, Jouni; Cieza, Alarcos; Pitkänen, Tuuli

    2014-01-01

    There has been a lack of comprehensive reviews targeting specific aspects of functioning and the difficulties faced by persons with alcohol dependence. The aim of the present review was to systematically compile the existing literature on activity limitations and participation restrictions as defined in the International Classification of Functioning, Disability and Health (ICF) in the context of alcohol dependence. A database search (MEDLINE and PsychINFO) was performed for studies published in English (2005-2012), examining the activity limitations and participation restrictions in alcohol dependence. Using a standardised protocol, information about the studies' characteristics and data on activity limitations and participation restrictions, their evolution, onset, determinants and associations with other variables were extracted from the studies under review. A total of 211 difficulties in activities and participation in persons with alcohol dependence were extracted from 125 papers. The spectrum of studies was wide, and their overall quality was good. A common reason for the exclusion of studies was an inconclusive definition of alcohol dependence. Issues with interpersonal interactions, economic and professional life, dealing with aggression and legal problems were the most frequently reported difficulties. Problems with high-risk behaviours and in seeking appropriate treatment were also common. The most frequent determinants of the onset and evolution of the identified difficulties were factors pertaining to the course of alcohol dependence. These difficulties were rarely the studies' focus; therefore, the data on their underlying causes and courses were limited. The results confirm that alcohol dependence profoundly affects the family and social network of the afflicted person. The treatment of alcohol dependence can contribute to the alleviation of these associated difficulties. The ICF offers a new perspective on evaluating the wide range of difficulties

  11. Thermal limits validation of gamma thermometer power adaption in CFE Laguna Verde 2 reactor core

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas V, G.; Banfield, J. [GE-Hitachi Nuclear Energy Americas LLC, Global Nuclear Fuel, Americas LLC, 3901 Castle Hayne Road, Wilmingtonm, North Carolina (United States); Avila N, A., E-mail: Gabriel.Cuevas-Vivas@ge.com [Comision Federal de Electricidad, Central Nucleoelectrica Laguna Verde, Carretera Cardel-Nautla Km 42.5, Alto Lucero, Veracruz (Mexico)

    2016-09-15

    This paper presents the status of GEH work on Gamma Thermometer (GT) validation using the signals of the instruments installed in the Laguna Verde Unit 2 reactor core. The long-standing technical collaboration between Comision Federal de Electricidad (CFE), Global Nuclear Fuel - Americas LLC (GNF) and GE-Hitachi Nuclear Energy Americas LLC (GEH) is moving forward with solid steps to a final implementation of GTs in a nuclear reactor core. Each GT is integrated into a slightly modified Local Power Range Monitor (LPRM) assembly. Six instrumentation strings are equipped with two gamma field detectors for a total of twenty-four bundles whose calculated powers are adapted to the instrumentation readings in addition to their use as calibration instruments for LPRMs. Since November 2007, the six GT instrumentation strings have been operable with almost no degradation by the strong neutron and gamma fluxes in the Laguna Verde Unit 2 reactor core. In this paper, the thermal limits, Critical Power Ratio (CPR) and maximum Linear Heat Generation Rate (LHGR), of bundles directly monitored by either Traverse In-core Probes (TIPs) or GTs are used to establish validation results that confirm the viability of TIP system replacement with automatic fixed in-core probes (AFIPs, GTs, in a Boiling Water Reactor. The new GNF steady-state reactor core simulator AETNA02 is used to obtain power and exposure distribution. Using this code with an updated methodology for GT power adaption, a reduced value of the GT interpolation uncertainty is obtained that is fed into the LHGR calculation. This new method achieves margin recovery for the adapted thermal limits for use in the Economic Simplified Boiling Water Reactor (ESBWR) or any other BWR in the future that employs a GT based AFIP system for local power measurements. (Author)

  12. Mantle dynamics with pressure- and temperature-dependent thermal expansivity and conductivity

    Science.gov (United States)

    Tosi, Nicola; Yuen, David A.; de Koker, Nico; Wentzcovitch, Renata M.

    2013-04-01

    In numerical simulations of mantle convection it is commonly assumed that the coefficients of thermal expansion α and thermal conduction k are either constant or pressure-dependent. Pressure changes are generally computed using parametrizations that rely on extrapolations of low-pressure data for a single upper-mantle phase. Here we collect data for both the pressure and temperature dependence of α from a database of first-principles calculations, and of k from recent experimental studies. We use these data-sets to construct analytical parametrizations of α and k for the major upper- and lower-mantle phases that can be easily incorporated into exisiting convection codes. We then analyze the impact of such parametrizations on Earth's mantle dynamics by employing two-dimensional numerical models of thermal convection. When α is the only variable parameter, both its temperature and pressure dependence enhance hot plumes and tend to inhibit the descent of cold downwellings. Taking into account a variable k leads to a strong increase of the bulk mantle temperature, which reduces the buoyancy available to amplify bottom boundary layer instabilities and causes mantle flow to be driven primarily by the instability of cold plates whose surface velocity also tends to rise. When both parameters are considered together, we observe an increased propensity to local layering which favors slab stagnation in the transition zone and subsequent thickening in the lower mantle. Furthermore, the values of k near the core-mantle boundary ultimately control the effect of this physical property on convection, which stresses the importance of determining the thermal conductivity of the post-perovskite phase.

  13. Thermal limits of wild and laboratory strains of two African malaria vector species, Anopheles arabiensis and Anopheles funestus

    Directory of Open Access Journals (Sweden)

    Lyons Candice L

    2012-07-01

    Full Text Available Abstract Background Malaria affects large parts of the developing world and is responsible for almost 800,000 deaths annually. As climates change, concerns have arisen as to how this vector-borne disease will be impacted by changing rainfall patterns and warming temperatures. Despite the importance and controversy surrounding the impact of climate change on the potential spread of this disease, little information exists on the tolerances of several of the vector species themselves. Methods Using a ramping protocol (to assess critical thermal limits - CT and plunge protocol (to assess lethal temperature limits - LT information on the thermal tolerance of two of Africa’s important malaria vectors, Anopheles arabiensis and Anopheles funestus was collected. The effects of age, thermal acclimation treatment, sex and strain (laboratory versus wild adults were investigated for CT determinations for each species. The effects of age and sex for adults and life stage (larvae, pupae, adults were investigated for LT determinations. Results In both species, females are more tolerant to low and high temperatures than males; larvae and pupae have higher upper lethal limits than do adults. Thermal acclimation of adults has large effects in some instances but small effects in others. Younger adults tend to be more tolerant of low or high temperatures than older age groups. Long-standing laboratory colonies are sufficiently similar in thermal tolerance to field-collected animals to provide reasonable surrogates when making inferences about wild population responses. Differences between these two vectors in their thermal tolerances, especially in larvae and pupae, are plausibly a consequence of different habitat utilization. Conclusions Limited plasticity is characteristic of the adults of these vector species relative to others examined to date, suggesting limited scope for within-generation change in thermal tolerance. These findings and the greater tolerance

  14. Temperature-Dependent Thermal Conductivity of High Strength Lightweight Raw Perlite Aggregate Concrete

    Science.gov (United States)

    Tandiroglu, Ahmet

    2010-06-01

    Twenty-four types of high strength lightweight concrete have been designed with raw perlite aggregate (PA) from the Erzincan Mollaköy region as new low-temperature insulation material. The effects of the water/cement ratio, the amount of raw PA, and the temperature on high strength lightweight raw perlite aggregate concrete (HSLWPAC) have been investigated. Three empirical equations were derived to correlate the thermal conductivity of HSLWPAC as a function of PA percentage and temperature depending on the water/cement ratio. Experimentally observed thermal conductivities of concrete samples were predicted 92 % of the time for each set of concrete matrices within 97 % accuracy and over the range from 1.457 W · m-1 · K-1 to 1.777 W · m-1 · K-1. The experimental investigation revealed that the usage of raw PA from the Erzincan Mollaköy region in concrete production reduces the concrete unit mass, increases the concrete strength, and furthermore, the thermal conductivity of the concrete has been improved. The proposed empirical correlations of thermal conductivity were considered to be applicable within the range of temperatures 203.15 K ≤ T ≤ 303.15 K in the form of λ = a( PAP b ) + c( T d ).

  15. Geometry dependence of temperature coefficient of resonant frequency in highly sensitive resonant thermal sensors

    Science.gov (United States)

    Inomata, Naoki; Ono, Takahito

    2017-08-01

    In this paper, the geometry dependence of the temperature coefficient of resonant frequency (TCRF) is investigated and compared with a theoretical thermal stress change using Si mechanical microresonators. The used resonators have Y, T, I (conventional double-supported type) and arrow shapes, and in each shape the resonant frequency change of the resonator is measured in relation to changes in the amount of heat input to the resonator. The change trend in the experimental resonant frequency and the theoretical thermal stress in changing the temperature are consist. The TCRF in each resonator is Y: -653, T: -162, I: -417, and the arrow is 174 ppm/K. These absolute values are much higher than those of conventional cantilevered Si resonators (-34.9 ppm/K). In addition, the frequency fluctuations based on Allan deviation are experimentally evaluated considering the theoretical thermal fluctuation noise. It is considered that use of this technique to improve the TCRF of resonators by changing the geometry has the possibility of creating a sensor with highly sensitive thermal detection.

  16. Fluctuation limit theorems for age-dependent critical binary branching systems

    Directory of Open Access Journals (Sweden)

    Murillo-Salas Antonio

    2011-03-01

    Full Text Available We consider an age-dependent branching particle system in ℝd, where the particles are subject to α-stable migration (0 < α ≤ 2, critical binary branching, and general (non-arithmetic lifetimes distribution. The population starts off from a Poisson random field in ℝd with Lebesgue intensity. We prove functional central limit theorems and strong laws of large numbers under two rescalings: high particle density, and a space-time rescaling that preserves the migration distribution. Properties of the limit processes such as Markov property, almost sure continuity of paths and generalized Langevin equation, are also investigated.

  17. Thermal stresses in a spherical pressure vessel having temperature-dependent, transversely isotropic, elastic properties

    Science.gov (United States)

    Tauchert, T. R.

    1976-01-01

    Rayleigh-Ritz and modified Rayleigh-Ritz procedures are used to construct approximate solutions for the response of a thick-walled sphere to uniform pressure loads and an arbitrary radial temperature distribution. The thermoelastic properties of the sphere are assumed to be transversely isotropic and nonhomogeneous; variations in the elastic stiffness and thermal expansion coefficients are taken to be an arbitrary function of the radial coordinate and temperature. Numerical examples are presented which illustrate the effect of the temperature-dependence upon the thermal stress field. A comparison of the approximate solutions with a finite element analysis indicates that Ritz methods offer a simple, efficient, and relatively accurate approach to the problem.

  18. Positive dependence of thermal conductivity on temperature in GeTe/Bi2Te3 superlattices: the contribution of electronic and particle wave lattice thermal conductivity

    Science.gov (United States)

    Tong, H.; Lan, F.; Liu, Y. J.; Zhou, L. J.; Wang, X. J.; He, Q.; Wang, K. Z.; Miao, X. S.

    2017-09-01

    Temperature-dependent thermal conductivity of phase-change material, GeTe/Bi2Te3 superlattices, has been investigated in the temperature range of 40-300 K. We have found that thermal conductivity increases with increasing temperature, which is contrary to the common results indicated by other works. In this paper, two possible mechanisms are suggested for this result. One is that the thermal conductivity is affected by the thermal boundary resistance at the interfaces between layers, and the other considers the factor of electronic thermal conductivity in the partially coherent regime which is based on the very wave-particle duality of phonons. Finally, the periodic thickness dependence of the thermal conductivity in GeTe/Bi2Te3 superlattices have been measured at room temperature, and the results indicate the main contribution of electron in the total thermal conductivity and the partially coherent regime of phonon. Thus we believe that the second explanation is more reasonable. The work here deepens the understanding of basic mechanisms of thermal transport in phase-change superlattices, and is instructive in modeling and simulation of phase change memories.

  19. Early onset alcohol dependence with high density of family history is not "male limited".

    Science.gov (United States)

    Magnusson, Asa; Göransson, Mona; Heilig, Markus

    2010-03-01

    Based on classical adoption studies, early onset type II alcoholism was originally described as "male limited." We examined the possible expression of this subtype in present day alcohol-dependent women. Detailed systematic assessment was obtained from 200 treatment-seeking alcohol-dependent women and 189 healthy population controls. Women fulfilling type II alcoholism criteria had higher alcoholism severity as measured by The Alcohol Use Disorders Identification Test and markedly higher use of illicit drugs. Both alcoholism subtypes scored higher than normal on anxiety and impulsivity traits, but type II women scored markedly higher on aggression subscales than either of the other groups. Importantly, density of family history was markedly higher in type II women, suggesting a higher heritability. Despite its original description as male limited, early onset alcoholism with high density of family history is likely to be a valid construct in women. Its recognition has important implications for diagnosis, treatment, and research. Published by Elsevier Inc.

  20. First spin-dependent WIMP-nucleon cross section limits from the LUX experiment

    CERN Document Server

    Akerib, D S; Bai, X; Bailey, A J; Balajthy, J; Beltrame, P; Bernard, E P; Bernstein, A; Biesiadzinski, T P; Boulton, E M; Bradley, A; Bramante, R; Cahn, S B; Carmona-Benitez, M C; Chan, C; Chapman, J J; Chiller, A A; Chiller, C; Currie, A; Cutter, J E; Davison, T J R; de Viveiros, L; Dobi, A; Dobson, J E Y; Druszkiewicz, E; Edwards, B N; Faham, C H; Fiorucci, S; Gaitskell, R J; Gehman, V M; Ghag, C; Gibson, K R; Gilchriese, M G D; Hall, C R; Hanhardt, M; Haselschwardt, S J; Hertel, S A; Hogan, D P; Horn, M; Huang, D Q; Ignarra, C M; Ihm, M; Jacobsen, R G; Ji, W; Kazkaz, K; Khaitan, D; Knoche, R; Larsen, N A; Lee, C; Lenardo, B G; Lesko, K T; Lindote, A; Lopes, M I; Malling, D C; Manalaysay, A; Mannino, R L; Marzioni, M F; McKinsey, D N; Mei, D M; Mock, J; Moongweluwan, M; Morad, J A; Murphy, A St J; Nehrkorn, C; Nelson, H N; Neves, F; O'Sullivan, K; Oliver-Mallory, K C; Ott, R A; Palladino, K J; Pangilinan, M; Pease, E K; Phelps, P; Reichhart, L; Rhyne, C; Shaw, S; Shutt, T A; Silva, C; Solovov, V N; Sorensen, P; Stephenson, S; Sumner, T J; Szydagis, M; Taylor, D J; Taylor, W; Tennyson, B P; Terman, P A; Tiedt, D R; To, W H; Tripathi, M; Tvrznikova, L; Uvarov, S; Verbus, J R; Webb, R C; White, J T; Whitis, T J; Witherell, M S; Wolfs, F L H; Yazdani, K; Young, S K; Zhang, C

    2016-01-01

    We present the first experimental constraints on the spin-dependent WIMP-nucleon elastic cross sections from LUX data acquired in 2013. LUX is a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), which is designed to observe the recoil signature of galactic WIMPs scattering from xenon nuclei. A profile likelihood ratio analysis of $1.4~\\times~10^{4}~\\text{kg}\\cdot~\\text{days}$ of fiducial exposure allows 90% CL upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of $\\sigma_n~=~9.4~\\times~10^{-41}~\\text{cm}^2$ ($\\sigma_p~=~2.9~\\times~10^{-39}~\\text{cm}^2$) at 33~GeV/c$^2$. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date for this channel.

  1. Angular-Dependent EDMR Linewidth for Spin-Dependent Space-Charge-Limited Conduction in a Polycrystalline Pentacene

    Directory of Open Access Journals (Sweden)

    Kunito Fukuda

    2017-08-01

    Full Text Available Spin-dependent space-charge-limited carrier conduction in a Schottky barrier diode using polycrystalline p-type π-conjugated molecular pentacene is explored using multiple-frequency electrically detected magnetic resonance (EDMR spectroscopy with a variable-angle configuration. The measured EDMR spectra are decomposed into two components derived, respectively, from mobile and trapped positive polarons. The linewidth of the EDMR signal for the trapped polarons increases with increasing resonance magnetic field for an in-plane configuration where the normal vector of the device substrate is perpendicular to the resonance magnetic field, while it is independent of the field for an out-of-plane configuration. This difference is consistent with the pentacene arrangement on the device substrate, where pentacene molecules exhibit a uniaxial orientation on the out-of-substrate plane. By contrast, the mobile polarons do not show anisotropic behavior with respect to the resonance magnetic field, indicating that the anisotropic effect is averaged out owing to carrier motion. These results suggest that the orientational arrangements of polycrystalline pentacene molecules in a nano thin film play a crucial role in spin-dependent electrical conduction.

  2. Angular-dependent EDMR linewidth for spin-dependent space charge limited conduction in a polycrystalline pentacene

    Science.gov (United States)

    Fukuda, Kunito; Asakawa, Naoki

    2017-08-01

    Spin-dependent space charge limited carrier conduction in a Schottky barrier diode using polycrystalline p-type π-conjugated molecular pentacene is explored using multiple-frequency electrically detected magnetic resonance (EDMR) spectroscopy with a variable-angle configuration. The measured EDMR spectra are decomposed into two components derived respectively from mobile and trapped positive polarons. The linewidth of the EDMR signal for the trapped polarons increases with increasing resonance magnetic field for an in-plane configuration where the normal vector of the device substrate is perpendicular to the resonance magnetic field, while it is independent of the field for an out-of-plane configuration. This difference is consistent with the pentacene arrangement on the device substrate, where pentacene molecules exhibit a uniaxial orientation on the out-of-substrate plane. By contrast, the mobile polarons do not show anisotropic behavior with respect to the resonance magnetic field, indicating that the anisotropic effect is averaged out owing to carrier motion. These results suggest that the orientational arrangements of polycrystalline pentacene molecules in a nano thin film play a crucial role in spin-dependent electrical conduction.

  3. Dark matter spin-dependent limits for WIMP interactions on {sup 19}F by PICASSO

    Energy Technology Data Exchange (ETDEWEB)

    Archambault, S.; Aubin, F.; Auger, M. [Departement de Physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Behnke, E. [Department of Physics and Astronomy, Indiana University South Bend, South Bend, IN 46634 (United States); Beltran, B. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Clark, K.; Dai, X.; Davour, A. [Department of Physics, Queen' s University, Kingston, K7L 3NG (Canada); Farine, J. [Department of Physics, Laurentian University, Sudbury, P3E 2C6 (Canada); Faust, R.; Genest, M.-H.; Giroux, G.; Gornea, R. [Departement de Physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Krauss, C. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Kumaratunga, S. [Departement de Physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Lawson, I. [SNOLAB, Sudbury, P3E 2C6 (Canada); Leroy, C.; Lessard, L. [Departement de Physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Levy, C. [Department of Physics, Queen' s University, Kingston, K7L 3NG (Canada); Levine, I. [Department of Physics and Astronomy, Indiana University South Bend, South Bend, IN 46634 (United States)

    2009-11-30

    The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on {sup 19}F using the superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the rejection of non-particle induced events are described. First results are presented for a subset of two detectors with target masses of {sup 19}F of 65 g and 69 g respectively and a total exposure of 13.75+-0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c{sup 2} new limits have been obtained on the spin-dependent cross section on {sup 19}F of sigma{sub F}=13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of sigma{sub p}=0.16 pb and sigma{sub n}=2.60 pb respectively (90% C.L.). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.

  4. Dark Matter Spin-Dependent Limits for WIMP Interactions on 19-F by PICASSO

    CERN Document Server

    Archambault, S; Auger, M; Behnke, E; Beltran, B; Clark, K; Dai, X; Davour, A; Farine, J; Faust, R; Genest, M-H; Giroux, G; Gornea, R; Krauss, C; Kumaratunga, S; Lawson, I; Leroy, C; Lessard, L; Levy, C; Levine, I; MacDonald, R; Martin, J -P; Nadeau, P; Noble, A; Piro, M -C; Pospísil, S; Shepherd, T; Starinski, N; Stekl, I; Storey, C; Wichoski, U; Zacek, V

    2009-01-01

    The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on $^{19}$F using the superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the rejection of non-particle induced events are described. First results are presented for a subset of two detectors with target masses of $^{19}$F of 65 g and 69 g respectively and a total exposure of 13.75 $\\pm$ 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c$^2$ new limits have been obtained on the spin-dependent cross section on $^{19}$F of $\\sigma_F$ = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of $\\sigma_p$ = 0.16 pb and $\\sigma_n$ = 2.60 pb respectively (90% C.L). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.

  5. Dark matter spin-dependent limits for WIMP interactions on {sup 19}F by PICASSO

    Energy Technology Data Exchange (ETDEWEB)

    Beltran, Berta, E-mail: bbeltran@phys.ualberta.c [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada)

    2010-01-01

    The PICASSO experiment at SNOLAB uses super-heated C{sub 4}F{sub 10} droplets suspended in a gel as a target sensitive to WIMP-proton spin-dependent elastic scattering. The phase II setup has been improved substantially in sensitivity by using an array of 32 detectors with an active mass of {approx}65 g each and largely reduced background. First results are presented for a subset of two detectors with target masses of {sup 19}F of 65 g and 69 g respectively and a total exposure of 13.75 {+-} 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c{sup 2} new limits have been obtained on the spin-dependent cross section on {sup 19}F of {sigma}{sub F} = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of {sigma}{sub p} = 0.15 pb and {sigma}{sub n} = 2.45 pb respectively (90% C.L). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.

  6. On the Soft Limit of the Large Scale Structure Power Spectrum: UV Dependence

    CERN Document Server

    Garny, Mathias; Porto, Rafael A; Sagunski, Laura

    2015-01-01

    We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. Thereby, we use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (anisotropic) parameters, such as spatial curvature, in a modified cosmology. We argue that both depend weakly on fluctuations deep in the UV. As a byproduct, this implies that the renormalized leading order coefficient(s) in the effective field theory (EFT) of large scale structures receive most of their contribution from modes close to the non-linear scale. Consequently, the UV dependence found in explicit computations within standard perturbation theory stems mostly from counter-term(s). We confront a simplified version of our non-perturbative equation against existent numerical simulations, and find good agr...

  7. Gravitation-dependent, thermally-induced self-diffraction in carbon nanotube solutions.

    Science.gov (United States)

    Ji, Wei; Chen, Weizhe; Lim, Sanhua; Lin, Jianyi; Guo, Zhixin

    2006-10-02

    We report the observation of thermally-induced self-diffraction in carbon nanotube (CNT) solutions under the influence of the gravity. We present a theoretical model in which CNTs are assumed to obey the Boltzmman distribution law. Under the approximations of small temperature rise and a very narrow distribution of CNT masses, the model simulation is consistent with the data measured at low laser powers. An immediate application of such a gravitation-dependent characteristic is the optical measurement for molecular weights of CNTs.

  8. The Temperature Condition of the Plate with Temperature-Dependent Thermal Conductivity and Energy Release

    Directory of Open Access Journals (Sweden)

    V. S. Zarubin

    2016-01-01

    Full Text Available The temperature state of a solid body, in addition to the conditions of its heat exchange with the environment, can greatly depend on the heat release (or heat absorption processes within the body volume. Among the possible causes of these processes should be noted such as a power release in the fuel elements of nuclear reactors, exothermic or endothermic chemical reactions in the solid body material, which respectively involve heat release or absorbtion, heat transfer of a part of the electric power in the current-carrying conductors (so-called Joule’s heat or the energy radiation penetrating into the body of a semitransparent material, etc. The volume power release characterizes an intensity of these processes.The extensive list of references to the theory of heat conductivity of solids offers solutions to problems to determine a stationary (steady over time and non-stationary temperature state of the solids (as a rule, of the canonical form, which act as the sources of volume power release. Thus, in general case, a possibility for changing power release according to the body volume and in solving the nonstationary problems also a possible dependence of this value on the time are taken into consideration.However, in real conditions the volume power release often also depends on the local temperature, and such dependence can be nonlinear. For example, with chemical reactions the intensity of heat release or absorption is in proportion to their rate, which, in turn, is sensitive to the temperature value, and a dependence on the temperature is exponential. A further factor that in such cases makes the analysis of the solid temperature state complicated, is dependence on the temperature and the thermal conductivity of this body material, especially when temperature distribution therein  is significantly non-uniform. Taking into account the influence of these factors requires the mathematical modeling methods, which allow us to build an adequate

  9. The Smoluchowski-Kramers Limit of Stochastic Differential Equations with Arbitrary State-Dependent Friction

    Science.gov (United States)

    Hottovy, Scott; McDaniel, Austin; Volpe, Giovanni; Wehr, Jan

    2015-06-01

    We study a class of systems of stochastic differential equations describing diffusive phenomena. The Smoluchowski-Kramers approximation is used to describe their dynamics in the small mass limit. Our systems have arbitrary state-dependent friction and noise coefficients. We identify the limiting equation and, in particular, the additional drift term that appears in the limit is expressed in terms of the solution to a Lyapunov matrix equation. The proof uses a theory of convergence of stochastic integrals developed by Kurtz and Protter. The result is sufficiently general to include systems driven by both white and Ornstein-Uhlenbeck colored noises. We discuss applications of the main theorem to several physical phenomena, including the experimental study of Brownian motion in a diffusion gradient.

  10. Thermal dissociation of molten KHSO4: Temperature dependence of Raman spectra and thermodynamics

    DEFF Research Database (Denmark)

    Knudsen, Christian B.; Kalampounias, Angelos G.; Fehrmann, Rasmus

    2008-01-01

    intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of the reaction equilibrium is derived. The method is used-along with the temperature-dependent features of the Raman spectra-to show that the studied equilibrium 2HSO(4)(-) (1) S2O72-(1) + H2O(g) is the only......Raman spectroscopy is used to study the thermal dissociation of molten KHSO4 at temperatures of 240-450 degrees C under static equilibrium conditions. Raman spectra obtained at 10 different temperatures for the molten phase and for the vapors thereof exhibit vibrational wavenumbers and relative...... band intensities inferring the occurrence of the temperature-dependent dissociation equilibrium 2HSO(4)(-) (1) S2O72-(1) + H2O(g). The Raman data are adequate for determining the partial pressures of H2O in the gas phase above the molten mixtures. A formalism for correlating relative Raman band...

  11. A finite element technique for non-deterministic thermal deformation analyses including temperature dependent material properties

    Science.gov (United States)

    Case, W. R., Jr.; Walston, W. H., Jr.

    1977-01-01

    A technique utilizing the finite element displacement method is developed for the static analysis of structures subjected to non-deterministic thermal loading in which the material properties, assumed isotropic, are temperature dependent. Matrix equations are developed for the first two statistical moments of the displacements using a third order series expansion for the displacements in terms of the random temperatures. Sample problems are included to demonstrate the range of applicability of the third order series solutions. These solutions are compared with results from Monte Carlo analyses and also, for some problems, with solutions obtained by numerically integrating equations for the statistical properties of the displacements. In general, it is shown that the effect of temperature dependent material properties can have a significant effect on the covariances of the displacements.

  12. Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter

    Energy Technology Data Exchange (ETDEWEB)

    Niwa, Akitsugu [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Nakaku, Sakai 599-8531 (Japan); Kobayashi, Takashi, E-mail: tkobaya@pe.osakafu-u.ac.jp; Nagase, Takashi; Naito, Hiroyoshi, E-mail: naito@pe.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Nakaku, Sakai 599-8531 (Japan); The Research Institute for Molecular Electronic Devices, Osaka Prefecture University, Sakai 599-8531 (Japan); Goushi, Kenichi; Adachi, Chihaya [Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2014-05-26

    Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100 K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process.

  13. Host and parasite thermal acclimation responses depend on the stage of infection.

    Science.gov (United States)

    Altman, Karie A; Paull, Sara H; Johnson, Pieter T J; Golembieski, Michelle N; Stephens, Jeffrey P; LaFonte, Bryan E; Raffel, Thomas R

    2016-07-01

    Global climate change is expected to alter patterns of temperature variability, which could influence species interactions including parasitism. Species interactions can be difficult to predict in variable-temperature environments because of thermal acclimation responses, i.e. physiological changes that allow organisms to adjust to a new temperature following a temperature shift. The goal of this study was to determine how thermal acclimation influences host resistance to infection and to test for parasite acclimation responses, which might differ from host responses in important ways. We tested predictions of three, non-mutually exclusive hypotheses regarding thermal acclimation effects on infection of green frog tadpoles (Lithobates clamitans) by the trematode parasite Ribeiroia ondatrae with fully replicated controlled-temperature experiments. Trematodes or tadpoles were independently acclimated to a range of 'acclimation temperatures' prior to shifting them to new 'performance temperatures' for experimental infections. Trematodes that were acclimated to intermediate temperatures (19-22 °C) had greater encystment success across temperatures than either cold- or warm-acclimated trematodes. However, host acclimation responses varied depending on the stage of infection (encystment vs. clearance): warm- (22-28 °C) and cold-acclimated (13-19 °C) tadpoles had fewer parasites encyst at warm and cold performance temperatures, respectively, whereas intermediate-acclimated tadpoles (19-25 °C) cleared the greatest proportion of parasites in the week following exposure. These results suggest that tadpoles use different immune mechanisms to resist different stages of trematode infection, and that each set of mechanisms has unique responses to temperature variability. Our results highlight the importance of considering thermal responses of both parasites and hosts when predicting disease patterns in variable-temperature environments. © 2016 The Authors. Journal of

  14. Temperature dependence of a microstructured SiC coherent thermal source

    Science.gov (United States)

    Hervé, Armande; Drévillon, Jérémie; Ezzahri, Younès; Joulain, Karl; De Sousa Meneses, Domingos; Hugonin, Jean-Paul

    2016-09-01

    By ruling a grating on a polar material that supports surface phonon-polaritons such as silicon carbide (SiC), it is possible to create directional and monochromatic thermal sources. So far, most of the studies have considered only materials with room temperature properties as the ones tabulated in Palik's handbooks. Recently, measurements have provided experimental data of the SiC dielectric function at different temperatures. Here we study, numerically, the effect of the temperature dependence of the dielectric function on the thermal emission of SiC gratings (1D grating, in a first approach), heated at different temperatures. When materials are heated, the position of the grating emissivity peak shifts towards higher wavelength values. A second consequence of the temperature dependence of optical properties is that room temperature designed gratings are not optimal for higher temperatures. However, by modifying the grating parameters, it is possible to find an emission peak, with a maximum of emissivity near 1, for each temperature. We tried first to catch some patterns in the emissivity variation. Then, we obtained a grating, which leads to an optimum emissivity for all available temperature data for SiC.

  15. Exceeding the solar cell Shockley-Queisser limit via thermal up-conversion of low-energy photons

    CERN Document Server

    Boriskina, Svetlana V

    2013-01-01

    Maximum efficiency of ideal single-junction photovoltaic (PV) cells is limited to 33% (for one sun illumination) by intrinsic losses such as band edge thermalization, radiative recombination, and inability to absorb below-bandgap photons. This intrinsic thermodynamic limit, named after Shockley and Queisser (S-Q), can be exceeded by utilizing low-energy photons either via their electronic up-conversion or via thermophotovoltaic (TPV) conversion process. However, electronic up-conversion systems have extremely low efficiencies, and practical temperature considerations limit the operation of TPV converters to the narrow-gap PV cells. Here we develop a conceptual design of a hybrid TPV platform, which exploits thermal up-conversion of low-energy photons and is compatible with conventional silicon PV cells by using spectral and directional selectivity of the up-converter. The hybrid platform offers sunlight-to-electricity conversion efficiency exceeding that imposed by the S-Q limit on the corresponding PV cells ...

  16. Size Dependent Optical Nonlinearity and Optical Limiting Properties of Water Soluble CdSe Quantum Dots

    Directory of Open Access Journals (Sweden)

    Anju K. Augustine

    2014-01-01

    Full Text Available We present third-order optical nonlinear absorption in CdSe quantum dots (QDs with particle sizes in the range of 4.16–5.25 nm which has been evaluated by the Z-scan technique. At an excitation irradiance of 0.54 GW/cm2 the CdSe QDs exhibit reverse saturation indicating a clear nonlinear behavior. Nonlinearity increases with particle size in CdSe QDs within the range of our investigations which in turn depends on the optical band gap. The optical limiting threshold of the QDs varies from 0.35 GW/cm2 to 0.57 GW/cm2 which makes CdSe QDs a promising candidate for reverse-saturable absorption based devices at high laser intensities such as optical limiters.

  17. Salinity-dependent limitation of photosynthesis and oxygen exchange in microbial mats

    DEFF Research Database (Denmark)

    Garcia-Pichel, F.; Kühl, Michael; Nübel, U.

    1999-01-01

    was specific for each community and in accordance with optimal performance at the respective salinity of origin. This pattern was lost after long-term exposure to varying salinities when responses to salinity were found to approach a general pattern of decreasing photosynthesis and oxygen exchange capacity...... with increasing salinity. Exhaustive measurements of oxygen export in the light, oxygen consumption in the dark and gross photosynthesis indicated that a salinity-dependent limitation of all three parameters occurred. Maximal values for all three parameters decreased exponentially with increasing salinity...

  18. Upper stellar mass limit by radiative feedback at low-metallicities: metallicity and accretion rate dependence

    Science.gov (United States)

    Fukushima, Hajime; Omukai, Kazuyuki; Hosokawa, Takashi

    2018-02-01

    We investigate the upper stellar mass limit set by radiative feedback for a forming star with various accretion rates and metallicities. Thus, we numerically solve the structures of both a protostar and its surrounding accretion envelope assuming a spherical symmetric and steady flow. The optical depth of the dust cocoon, a dusty part of the accretion envelope, differs for direct light from the stellar photosphere and diffuse light re-emitted as dust thermal emission. As a result, varying the metallicity qualitatively changes the way that the radiative feedback suppresses the accretion flow. With a fixed accretion rate of 10-3 M⊙ yr-1, both direct and diffuse light jointly operate to prevent mass accretion at Z ≳ 10-1 Z⊙. At Z ≲ 10-1 Z⊙, the diffuse light is no longer effective and the direct light solely limits the mass accretion. At Z ≲ 10-3 Z⊙, formation of the H II region plays an important role in terminating the accretion. The resultant upper mass limit increases with decreasing metallicity, from a few × 10 M⊙ to ∼103 M⊙ over Z = 1 Z⊙-10-4 Z⊙. We also illustrate how the radiation spectrum of massive star-forming cores changes with decreasing metallicity. First, the peak wavelength of the spectrum, which is located around 30 μm at 1 Z⊙, shifts to < 3 μm at Z ≲ 0.1 Z⊙. Secondly, a characteristic feature at 10 μm due to the amorphous silicate band appears as a dip at 1 Z⊙, but changes to a bump at Z ≲ 0.1 Z⊙. Using these spectral signatures, we can search massive accreting protostars in nearby low-metallicity environments with upcoming observations.

  19. Investment in secreted enzymes during nutrient-limited growth is utility dependent.

    Science.gov (United States)

    Cezairliyan, Brent; Ausubel, Frederick M

    2017-09-12

    Pathogenic bacteria secrete toxins and degradative enzymes that facilitate their growth by liberating nutrients from the environment. To understand bacterial growth under nutrient-limited conditions, we studied resource allocation between cellular and secreted components by the pathogenic bacterium Pseudomonas aeruginosa during growth on a protein substrate that requires extracellular digestion by secreted proteases. We identified a quantitative relationship between the rate of increase of cellular biomass under nutrient-limiting growth conditions and the rate of increase in investment in secreted proteases. Production of secreted proteases is stimulated by secreted signals that convey information about the utility of secreted proteins during nutrient-limited growth. Growth modeling using this relationship recapitulated the observed kinetics of bacterial growth on a protein substrate. The proposed regulatory strategy suggests a rationale for quorum-sensing-dependent stimulation of the production of secreted enzymes whereby investment in secreted enzymes occurs in proportion to the utility they confer. Our model provides a framework that can be applied toward understanding bacterial growth in many environments where growth rate is limited by the availability of nutrients.

  20. Thermal Skin Damage During Reirradiation and Hyperthermia Is Time-Temperature Dependent

    Energy Technology Data Exchange (ETDEWEB)

    Bakker, Akke, E-mail: akke.bakker@amc.uva.nl [Department of Radiation Oncology, Academic Medical Center (AMC), Amsterdam (Netherlands); Kolff, M. Willemijn [Department of Radiation Oncology, Academic Medical Center (AMC), Amsterdam (Netherlands); Holman, Rebecca [Clinical Research Unit, Academic Medical Center (AMC), Amsterdam (Netherlands); Leeuwen, Caspar M. van; Korshuize-van Straten, Linda; Kroon-Oldenhof, Rianne de; Rasch, Coen R.N.; Tienhoven, Geertjan van; Crezee, Hans [Department of Radiation Oncology, Academic Medical Center (AMC), Amsterdam (Netherlands)

    2017-06-01

    Purpose: To investigate the relationship of thermal skin damage (TSD) to time–temperature isoeffect levels for patients with breast cancer recurrence treated with reirradiation plus hyperthermia (reRT + HT), and to investigate whether the treatment history of previous treatments (scar tissue) is a risk factor for TSD. Methods and Materials: In this observational study, temperature characteristics of hyperthermia sessions were analyzed in 262 patients with recurrent breast cancer treated in the AMC between 2010 and 2014 with reirradiation and weekly hyperthermia for 1 hour. Skin temperature was measured using a median of 42 (range, 29-82) measurement points per hyperthermia session. Results: Sixty-eight patients (26%) developed 79 sites of TSD, after the first (n=26), second (n=17), third (n=27), and fourth (n=9) hyperthermia session. Seventy percent of TSD occurred on or near scar tissue. Scar tissue reached higher temperatures than other skin tissue (0.4°C, P<.001). A total of 102 measurement points corresponded to actual TSD sites in 35 of 79 sessions in which TSD developed. Thermal skin damage sites had much higher maximum temperatures than non-TSD sites (2.8°C, P<.001). Generalized linear mixed models showed that the probability of TSD is related to temperature and thermal dose values (P<.001) and that scar tissue is more at risk (odds ratio 0.4, P<.001). Limiting the maximum temperature of a measurement point to 43.7°C would mean that the probability of observing TSD was at most 5%. Conclusion: Thermal skin damage during reRT + HT for recurrent breast cancer was related to higher local temperatures and time–temperature isoeffect levels. Scar tissue reached higher temperatures than other skin tissue, and TSD occurred at lower temperatures and thermal dose values in scar tissue compared with other skin tissue. Indeed, TSD developed often on and around scar tissue from previous surgical procedures.

  1. Oxygen limitation of thermal tolerance in cod, Gadus morhua L., studied by magnetic resonance imaging and on-line venous oxygen monitoring.

    Science.gov (United States)

    Lannig, Gisela; Bock, Christian; Sartoris, Franz J; Pörtner, Hans O

    2004-10-01

    The hypothesis of an oxygen-limited thermal tolerance due to restrictions in cardiovascular performance at extreme temperatures was tested in Atlantic cod, Gadus morhua (North Sea). Heart rate, changes in arterial and venous blood flow, and venous oxygen tensions were determined during an acute temperature change to define pejus ("getting worse") temperatures that border the thermal optimum range. An exponential increase in heart rate occurred between 2 and 16 degrees C (Q(10) = 2.38 +/- 0.35). Thermal sensitivity was reduced beyond 16 degrees C when cardiac arrhythmia became visible. Flow-weighted magnetic resonance imaging (MRI) measurements of temperature-dependent blood flow revealed no exponential but a hyperbolic increase of blood flow with a moderate linear increase at temperatures >4 degrees C. Therefore, temperature-dependent heart rate increments are not mirrored by similar increments in blood flow. Venous Po(2) (Pv(O(2))), which reflects the quality of oxygen supply to the heart of cod (no coronary circulation present), followed an inverse U-shaped curve with highest Pv(O(2)) levels at 5.0 +/- 0.2 degrees C. Thermal limitation of circulatory performance in cod set in below 2 degrees C and beyond 7 degrees C, respectively, characterized by decreased Pv(O(2)). Further warming led to a sharp drop in Pv(O(2)) beyond 16.1 +/- 1.2 degrees C in accordance with the onset of cardiac arrhythmia and, likely, the critical temperature. In conclusion, progressive cooling or warming brings cod from a temperature range of optimum cardiac performance into a pejus range, when aerobic scope falls before critical temperatures are reached. These patterns might cause a shift in the geographical distribution of cod with global warming.

  2. JNK mitogen-activated protein kinase limits calcium-dependent chloride secretion across colonic epithelial cells.

    LENUS (Irish Health Repository)

    Donnellan, Fergal

    2010-01-01

    Neuroimmune agonists induce epithelial Cl(-) secretion through elevations in intracellular Ca2+ or cAMP. Previously, we demonstrated that epidermal growth factor receptor (EGFR) transactivation and subsequent ERK MAPK activation limits secretory responses to Ca2+-dependent, but not cAMP-dependent, agonists. Although JNK MAPKs are also expressed in epithelial cells, their role in regulating transport function is unknown. Here, we investigated the potential role for JNK in regulating Cl(-) secretion in T(84) colonic epithelial cells. Western blot analysis revealed that a prototypical Ca2+-dependent secretagogue, carbachol (CCh; 100 microM), induced phosphorylation of both the 46-kDa and 54-kDa isoforms of JNK. This effect was mimicked by thapsigargin (TG), which specifically elevates intracellular Ca2+, but not by forskolin (FSK; 10 microM), which elevates cAMP. CCh-induced JNK phosphorylation was attenuated by the EGFR inhibitor, tyrphostin-AG1478 (1 microM). Pretreatment of voltage-clamped T(84) cells with SP600125 (2 microM), a specific JNK inhibitor, potentiated secretory responses to both CCh and TG but not to FSK. The effects of SP600125 on CCh-induced secretion were not additive with those of the ERK inhibitor, PD98059. Finally, in apically permeabilized T(84) cell monolayers, SP600125 potentiated CCh-induced K+ conductances but not Na+\\/K+ATPase activity. These data demonstrate a novel role for JNK MAPK in regulating Ca2+ but not cAMP-dependent epithelial Cl(-) secretion. JNK activation is mediated by EGFR transactivation and exerts its antisecretory effects through inhibition of basolateral K+ channels. These data further our understanding of mechanisms regulating epithelial secretion and underscore the potential for exploitation of MAPK-dependent signaling in treatment of intestinal transport disorders.

  3. tRNA-dependent cysteine biosynthetic pathway represents a strategy to increase cysteine contents by preventing it from thermal degradation: thermal adaptation of methanogenic archaea ancestor.

    Science.gov (United States)

    Qu, Ge; Wang, Wei; Chen, Ling-Ling; Qian, Shao-Song; Zhang, Hong-Yu

    2009-10-01

    Although cysteine (Cys) is beneficial to stabilize protein structures, it is not prevalent in thermophiles. For instance, the Cys contents in most thermophilic archaea are only around 0.7%. However, methanogenic archaea, no matter thermophilic or not, contain relatively abundant Cys, which remains elusive for a long time. Recently, Klipcan et al. correlated this intriguing property of methanogenic archaea with their unique tRNA-dependent Cys biosynthetic pathway. But, the deep reasons underlying the correlation are ambiguous. Considering the facts that free Cys is thermally labile and the tRNA-dependent Cys biosynthesis avoids the use of free Cys, we speculate that the unique Cys biosynthetic pathway represents a strategy to increase Cys contents by preventing it from thermal degradation, which may be relevant to the thermal adaptation of methanogenic archaea ancestor.

  4. Thermal flux limited electron Kapitza conductance in copper-niobium multilayers

    Science.gov (United States)

    Cheaito, Ramez; Hattar, Khalid; Gaskins, John T.; Yadav, Ajay K.; Duda, John C.; Beechem, Thomas E.; Ihlefeld, Jon F.; Piekos, Edward S.; Baldwin, Jon K.; Misra, Amit; Hopkins, Patrick E.

    2015-03-01

    We study the interplay between the contributions of electron thermal flux and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the electron diffuse mismatch model. Our results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the electron energy flux in the metallic layers, rather than electron mean free path or scattering processes at the interface.

  5. Thermal flux limited electron Kapitza conductance in copper-niobium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cheaito, Ramez; Gaskins, John T.; Duda, John C.; Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Hattar, Khalid; Beechem, Thomas E.; Ihlefeld, Jon F.; Piekos, Edward S. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yadav, Ajay K. [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Baldwin, Jon K. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Misra, Amit [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2015-03-02

    We study the interplay between the contributions of electron thermal flux and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the electron diffuse mismatch model. Our results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the electron energy flux in the metallic layers, rather than electron mean free path or scattering processes at the interface.

  6. Analysis of Radiative Radial Fin with Temperature-Dependent Thermal Conductivity Using Nonlinear Differential Transformation Methods

    Directory of Open Access Journals (Sweden)

    Mohsen Torabi

    2013-01-01

    Full Text Available Radiative radial fin with temperature-dependent thermal conductivity is analyzed. The calculations are carried out by using differential transformation method (DTM, which is a seminumerical-analytical solution technique that can be applied to various types of differential equations, as well as the Boubaker polynomials expansion scheme (BPES. By using DTM, the nonlinear constrained governing equations are reduced to recurrence relations and related boundary conditions are transformed into a set of algebraic equations. The principle of differential transformation is briefly introduced and then applied to the aforementioned equations. Solutions are subsequently obtained by a process of inverse transformation. The current results are then compared with previously obtained results using variational iteration method (VIM, Adomian decomposition method (ADM, homotopy analysis method (HAM, and numerical solution (NS in order to verify the accuracy of the proposed method. The findings reveal that both BPES and DTM can achieve suitable results in predicting the solution of such problems. After these verifications, we analyze fin efficiency and the effects of some physically applicable parameters in this problem such as radiation-conduction fin parameter, radiation sink temperature, heat generation, and thermal conductivity parameters.

  7. Burn-up dependent steady-state thermal hydraulic analysis of Pakistan research reactor-1

    Directory of Open Access Journals (Sweden)

    Muhammad Atta

    2011-01-01

    Full Text Available The burn-up dependent steady-state thermal hydraulic analysis of Pakistan research reactor-1, reference operating core, has been carried out utilizing standard computer codes WIMS/D4, CITATION, and RELAP5/MOD3.4. Reactor codes WIMS/D4 and CITATION have been used for the calculations of neutronic parameters including peaking factors and power profiles at different burn-up considering a xenon free core and also the equilibrium xenon values. RELAP5/MOD3.4 code was utilized for the determination of peak fuel centerline, clad and coolant temperatures to ensure the safety of the reactor throughout the cycle. The calculations reveal that the reactor is safe and no nucleate boiling will commence at any part of the core throughout the cycle and that the safety margin increases with burnup as peaking factors decrease.

  8. Chemical potential dependence of particle ratios within a unified thermal approach

    Energy Technology Data Exchange (ETDEWEB)

    Bashir, I., E-mail: inamhep@gmail.com; Nanda, H.; Uddin, S. [Central University, Department of Physics, Jamia Millia Islamia (India)

    2016-06-15

    A unified statistical thermal freeze-out model (USTFM) is used to study the chemical potential dependence of identified particle ratios at mid-rapidity in heavy-ion collisions. We successfully reproduce the experimental data ranging from SPS energies to LHC energies, suggesting the statistical nature of the particle production in these collisions and hence the validity of our approach. The behavior of the freeze-out temperature is studied with respect to chemical potential. The freeze-out temperature is found to be universal at the RHIC and LHC and is close to the QCD predicted phase transition temperature, suggesting that the chemical freeze-out occurs soon after the hadronization takes place.

  9. Analytic P{sub 1} solutions for time-dependent, thermal radiative transfer in several geometries

    Energy Technology Data Exchange (ETDEWEB)

    McClarren, Ryan G. [Computational Physics and Methods Group (CCS-2), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)], E-mail: ryanmc@lanl.gov; Paul Holloway, James [Department of Nuclear Engineering and Radiological Sciences, College of Engineering, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 2104 (United States); Brunner, Thomas A. [Sandia National Laboratories, P.O. Box 5800, MS 1186, Albuquerque, NM 87185 1186 (United States)

    2008-02-15

    We present several solutions for the time-dependent P{sub 1} approximation (telegrapher's equation) coupled to thermal radiative transfer with C{sub v}{proportional_to}T{sup 3}. Our solutions are based on the energy density Green's function in slab geometry, which we derive exactly. The analytic P{sub 1} solution is compared with analytic transport and diffusion solutions on one of the Su-Olson benchmark problems. Also, we transform the slab geometry Green's function into the solution from a point source (the 1D spherical Green's function) and an infinite line source (the 1D cylindrical Green's function). We evaluate the P{sub 1} solution to the line source and compare the result with a solution generated by a P{sub n} numerical method.

  10. Predator-dependent functional response in wolves: from food limitation to surplus killing.

    Science.gov (United States)

    Zimmermann, Barbara; Sand, Håkan; Wabakken, Petter; Liberg, Olof; Andreassen, Harry Peter

    2015-01-01

    The functional response of a predator describes the change in per capita kill rate to changes in prey density. This response can be influenced by predator densities, giving a predator-dependent functional response. In social carnivores which defend a territory, kill rates also depend on the individual energetic requirements of group members and their contribution to the kill rate. This study aims to provide empirical data for the functional response of wolves Canis lupus to the highly managed moose Alces alces population in Scandinavia. We explored prey and predator dependence, and how the functional response relates to the energetic requirements of wolf packs. Winter kill rates of GPS-collared wolves and densities of cervids were estimated for a total of 22 study periods in 15 wolf territories. The adult wolves were identified as the individuals responsible for providing kills to the wolf pack, while pups could be described as inept hunters. The predator-dependent, asymptotic functional response models (i.e. Hassell-Varley type II and Crowley-Martin) performed best among a set of 23 competing linear, asymptotic and sigmoid models. Small wolf packs acquired >3 times as much moose biomass as required to sustain their field metabolic rate (FMR), even at relatively low moose abundances. Large packs (6-9 wolves) acquired less biomass than required in territories with low moose abundance. We suggest the surplus killing by small packs is a result of an optimal foraging strategy to consume only the most nutritious parts of easy accessible prey while avoiding the risk of being detected by humans. Food limitation may have a stabilizing effect on pack size in wolves, as supported by the observed negative relationship between body weight of pups and pack size. © 2014 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

  11. The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

    Directory of Open Access Journals (Sweden)

    D. M. Miles

    2017-10-01

    Full Text Available Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic feedback. Scientific fluxgate magnetometers typically employ some form of temperature compensation and support and constrain wire sense coils with bobbins constructed from materials such as MACOR machinable ceramic (Corning Inc. which are selected for their ultra-low thermal deformation rather than for robustness, cost, or ease of manufacturing. We present laboratory results comparing the performance of six geometrically and electrically matched fluxgate sensors in which the material used to support the windings and for the base of the sensor is varied. We use a novel, low-cost thermal calibration procedure based on a controlled sinusoidal magnetic source and quantitative spectral analysis to measure the thermal gain dependence of fluxgate magnetometer sensors at the ppm°C−1 level in a typical magnetically noisy university laboratory environment. We compare the thermal gain dependence of sensors built from MACOR, polyetheretherketone (PEEK engineering plastic (virgin, 30 % glass filled and 30 % carbon filled, and acetal to examine the trade between the thermal properties of the material, the impact on the thermal gain dependence of the fluxgate, and the cost and ease of manufacture. We find that thermal gain dependence of the sensor varies as one half of the material properties of the bobbin supporting the wire sense coils rather than being directly related as has been historically thought. An experimental sensor constructed from 30 % glass-filled PEEK (21.6 ppm°C−1 had a thermal gain dependence within 5 ppm°C−1 of a traditional sensor constructed from MACOR ceramic (8.1

  12. The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

    Science.gov (United States)

    Miles, David M.; Mann, Ian R.; Kale, Andy; Milling, David K.; Narod, Barry B.; Bennest, John R.; Barona, David; Unsworth, Martyn J.

    2017-10-01

    Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic feedback. Scientific fluxgate magnetometers typically employ some form of temperature compensation and support and constrain wire sense coils with bobbins constructed from materials such as MACOR machinable ceramic (Corning Inc.) which are selected for their ultra-low thermal deformation rather than for robustness, cost, or ease of manufacturing. We present laboratory results comparing the performance of six geometrically and electrically matched fluxgate sensors in which the material used to support the windings and for the base of the sensor is varied. We use a novel, low-cost thermal calibration procedure based on a controlled sinusoidal magnetic source and quantitative spectral analysis to measure the thermal gain dependence of fluxgate magnetometer sensors at the ppm°C-1 level in a typical magnetically noisy university laboratory environment. We compare the thermal gain dependence of sensors built from MACOR, polyetheretherketone (PEEK) engineering plastic (virgin, 30 % glass filled and 30 % carbon filled), and acetal to examine the trade between the thermal properties of the material, the impact on the thermal gain dependence of the fluxgate, and the cost and ease of manufacture. We find that thermal gain dependence of the sensor varies as one half of the material properties of the bobbin supporting the wire sense coils rather than being directly related as has been historically thought. An experimental sensor constructed from 30 % glass-filled PEEK (21.6 ppm°C-1) had a thermal gain dependence within 5 ppm°C-1 of a traditional sensor constructed from MACOR ceramic (8.1 ppm°C-1). If a modest increase in thermal

  13. Simulation of electrical and thermal behavior of high temperature superconducting fault current limiting transformer (HTc-SFCLT)

    Energy Technology Data Exchange (ETDEWEB)

    Kurupakorn, C [Department of Electrical Engineering and Computer Science, Nagoya University, Nagoya 464-8603 (Japan); Kojima, H [EcoTopia Science Institute, Nagoya University, Nagoya 464-8603 (Japan); Hayakawa, N [Department of Electrical Engineering and Computer Science, Nagoya University, Nagoya 464-8603 (Japan); Endo, F [EcoTopia Science Institute, Nagoya University, Nagoya 464-8603 (Japan); Kashima, N [Chubu Electric Power Co., Inc., Nagoya 459-8522 (Japan); Nagaya, S [Chubu Electric Power Co., Inc., Nagoya 459-8522 (Japan); Noe, M [Forschungszentrum Karlsruhe, Karlsruhe D-76021 (Germany); Okubo, H [EcoTopia Science Institute, Nagoya University, Nagoya 464-8603 (Japan)

    2006-06-01

    Superconducting Fault Current Limiting Transformer (SFCLT) is expected to perform functions both of transformer in the normal operating condition and of fault current limiter in the system fault condition. As the Phase-3 of the SFCLT project, we have been developing SFCLT based on Bi2212/CuNi bulk coils at LN{sub 2} temperature and verified its technical feasibility. In this paper, we developed a numerical model for evaluation of the electrical and thermal behavior of HTc-SFCLT such as current limitation and recovery characteristics. This model took into account E-J characteristics of Bi2212/CuNi bulk coil and its electrical and thermal transient phenomena during the operation of HTc-SFCLT. The simulated current agreed well with the experimental data with the error of less than 5%. The excellent current limitation and self recovery characteristics obtained by the experiments could also be reproduced. With the numerical model, current and thermal behavior of HTc-SFCLT was simulated for different parameters of conductor configuration, which would be useful for the future design and optimization of HTc-SFCLT.

  14. Observational limitations of Bose-Einstein photon statistics and radiation noise in thermal emission

    Science.gov (United States)

    Lee, Y.-J.; Talghader, J. J.

    2018-01-01

    For many decades, theory has predicted that Bose-Einstein statistics are a fundamental feature of thermal emission into one or a few optical modes; however, the resulting Bose-Einstein-like photon noise has never been experimentally observed. There are at least two reasons for this: (1) Relationships to describe the thermal radiation noise for an arbitrary mode structure have yet to be set forth, and (2) the mode and detector constraints necessary for the detection of such light is extremely hard to fulfill. Herein, photon statistics and radiation noise relationships are developed for systems with any number of modes and couplings to an observing space. The results are shown to reproduce existing special cases of thermal emission and are then applied to resonator systems to discuss physically realizable conditions under which Bose-Einstein-like thermal statistics might be observed. Examples include a single isolated cavity and an emitter cavity coupled to a small detector space. Low-mode-number noise theory shows major deviations from solely Bose-Einstein or Poisson treatments and has particular significance because of recent advances in perfect absorption and subwavelength structures both in the long-wave infrared and terahertz regimes. These microresonator devices tend to utilize a small volume with few modes, a regime where the current theory of thermal emission fluctuations and background noise, which was developed decades ago for free-space or single-mode cavities, has no derived solutions.

  15. THERMAL AND RADIATIVE ACTIVE GALACTIC NUCLEUS FEEDBACK HAVE A LIMITED IMPACT ON STAR FORMATION IN HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Orianne; Juneau, Stéphanie; Bournaud, Frédéric; Gabor, Jared M., E-mail: orianne.roos@cea.fr [CEA-Saclay, F-91190 Gif-sur-Yvette (France)

    2015-02-10

    The effects of active galactic nuclei (AGNs) on their host galaxies depend on the coupling between the injected energy and the interstellar medium (ISM). Here, we model and quantify the impact of long-range AGN ionizing radiation—in addition to the often considered small-scale energy deposition—on the physical state of the multi-phase ISM of the host galaxy and on its total star formation rate (SFR). We formulate an AGN spectral energy distribution matched with observations, which we use with the radiative transfer (RT) code Cloudy to compute AGN ionization in a simulated high-redshift disk galaxy. We use a high-resolution (∼6 pc) simulation including standard thermal AGN feedback and calculate RT in post-processing. Surprisingly, while these models produce significant AGN-driven outflows, we find that AGN ionizing radiation and heating reduce the SFR by a few percent at most for a quasar luminosity (L {sub bol} = 10{sup 46.5} erg s{sup –1}). Although the circumgalactic gaseous halo can be kept almost entirely ionized by the AGN, most star-forming clouds (n ≳ 10{sup 2} {sup –} {sup 3} cm{sup –3}) and even the reservoirs of cool atomic gas (n ∼ 0.3-10 cm{sup –3})—which are the sites of future star formation (SF; 100-200 Myr), are generally too dense to be significantly affected. Our analysis ignores any absorption from a putative torus, making our results upper limits on the effects of ionizing radiation. Therefore, while the AGN-driven outflows can remove substantial amounts of gas in the long term, the impact of AGN feedback on the SF efficiency in the interstellar gas in high-redshift galaxies is marginal, even when long-range radiative effects are accounted for.

  16. Optimum comfort limits determination through the characteristics of asymmetric thermal radiation in a heated floor space, "ondol".

    Science.gov (United States)

    Yoon, Y J; Park, S D; Sohn, J Y

    1992-09-01

    This study was undertaken to evaluate the effects of the asymmetric radiation on thermal comfort, and to suggest the optimum comfort limits in a radiant heating space. The index of V.R.T. (Vector Radiant Temperature) was used to describe the environmental quality of the heated floor space. Optimum comfort limits of this space were suggested through both theoretical and empirical studies. It is recommended to use not only man's sensation of the ambient air but also that of the floor surface for the determination of the optimum comfort limits on the heated floor space such as an "Ondol" in Korea. In the present study the optimum comfort limits were suggested in terms of the V.R.T. The optimum limits obtained were as follows: the vector radiant temperature 11.0 approximately 15.0 K.

  17. Threshold-dependent climate effects and high mortality limit recruitment and recovery of the Kattegat cod

    DEFF Research Database (Denmark)

    Lindegren, Martin; Eero, Margit

    2013-01-01

    Cod in the Kattegat is one of the most dramatic examples of stock collapse, where despite large management efforts, almost no signs of recovery have been observed. We investigate how multiple physical and biological factors could potentially influence recruitment and recovery of Kattegat cod, using......), but only during periods of low stock size. Our results indicate that the long-term decrease and the present poor state of the Kattegat cod stock is likely caused by high total mortality rates and stock-size dependent effects of climate which together are currently preventing recovery. In addition, we...... illustrate how only a drastic reduction in total mortalities, primarily by limiting unintended bycatch and discards, may promote a recovery of the stock. This knowledge is important for evaluating the success or failure of various management measures which have been employed to recover the stock...

  18. [Limitations of insulin-dependent drugs in the treatment of type 2 diabetes mellitus].

    Science.gov (United States)

    Valerón, Pino Fuente; de Pablos-Velasco, Pedro L

    2013-09-01

    In this study, we review the efficacy and safety limitations of insulin-dependent oral antidiabetic agents. In terms of efficiency, the main drawback of metformin, sulfonylureas, gliptins and -to a lesser extent-glitazones is durability. No drug per se is able to maintain stable blood glucose control for years. Metformin, sulfonylureas and gliptins have demonstrated safety. Experience with the first two drug groups is more extensive. The main adverse effect of metformin is gastrointestinal discomfort. Major concerns related to the use of sulfonylureas are hypoglycemia and weight gain. The use of pioglitazone has been associated with an increased risk of bladder cancer, edema, heart failure, weight gain, and distal bone fractures in postmenopausal women. The most common adverse reactions associated with glucagon-like peptide-1 agonists are gastrointestinal discomfort that sometimes leads to treatment discontinuation. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  19. The effects of thermal acclimation on lethal temperatures and critical thermal limits in the green vegetable bug, Nezara viridula (L. (Hemiptera: Pentatomidae

    Directory of Open Access Journals (Sweden)

    Pol eChanthy

    2012-12-01

    Full Text Available According to geographical distribution, Nezara viridula (Heteroptera: Pentatomidae can be found across tropical, subtropical and temperate regions and this pattern is assumed to reflect differences in thermal adaptation, particularly in cold tolerance. Here the lethal temperature and critical thermal limits (thermal tolerance are examined for N. viridula. The upper lethal temperature for N. viridula at two contrasting climate locations (Breeza and Grafton, New South Wales, Australia was 40.3ºC with 20% survival under the stress of high temperature. The lower lethal temperature did not differ between these two populations and was -8.0ºC with 20% survival under low temperature stress. Survival of N. viridula increased after acclimation at high temperature for seven days. In contrast, when acclimated at lower temperatures (10 and 15ºC, survival of Breeza and Grafton N. viridula was lower than 20% at -8.0ºC.Control-reared N. viridula adults (25ºC had a mean CTMinOnset (cold stupor of 1.3 ± 2.1ºC and a mean CTMax (heat coma of 45.9 ± 0.9ºC. After 7 days of acclimation at 10, 20, 30, or 35ºC, N. viridula adults exhibited a 1ºC change in CTMax and a ~ 1.5ºC change in CTMinOnset. CTMax and CTMinOnset of Breeza and Grafton N. viridula populations did not differ across acclimation temperatures. These results suggest that short-term temperature acclimation is more important than provenance for determining lethal temperatures and critical thermal limits in N. viridula.

  20. Spin-dependent Seebeck Effect, Thermal Colossal Magnetoresistance and Negative Differential Thermoelectric Resistance in Zigzag Silicene Nanoribbon Heterojunciton.

    Science.gov (United States)

    Fu, Hua-Hua; Wu, Dan-Dan; Zhang, Zu-Quan; Gu, Lei

    2015-05-22

    Spin-dependent Seebeck effect (SDSE) is one of hot topics in spin caloritronics, which examine the relationships between spin and heat transport in materials. Meanwhile, it is still a huge challenge to obtain thermally induced spin current nearly without thermal electron current. Here, we construct a hydrogen-terminated zigzag silicene nanoribbon heterojunction, and find that by applying a temperature difference between the source and the drain, spin-up and spin-down currents are generated and flow in opposite directions with nearly equal magnitudes, indicating that the thermal spin current dominates the carrier transport while the thermal electron current is much suppressed. By modulating the temperature, a pure thermal spin current can be achieved. Moreover, a thermoelectric rectifier and a negative differential thermoelectric resistance can be obtained in the thermal electron current. Through the analysis of the spin-dependent transport characteristics, a phase diagram containing various spin caloritronic phenomena is provided. In addition, a thermal magnetoresistance, which can reach infinity, is also obtained. Our results put forward an effective route to obtain a spin caloritronic material which can be applied in future low-power-consumption technology.

  1. To the description of the temperature and pressure dependences of the thermal conductivity of sandstone and ceramics

    Science.gov (United States)

    Emirov, S. N.; Beybalaev, V. D.; Gadzhiev, G. G.; Ramazanova, A. E.; Amirova, A. A.; Aliverdiev, A. A.

    2017-11-01

    Here we present the results of an experimental study of the temperature and pressure dependences of the heat conductivity of composite compounds. The thermal conductivity of sandstone was measured by the absolute stationary method for pressures up to 400 MPa in the temperature range 273-523 K. From these experimental data we have proposed the equation describing the dependence of the thermal conductivity from the pressure and temperature. We have found that under the action of hydrostatic pressure the intensive growth of the heat-conductivity of gas-saturated sandstone is mainly up to 100 MPa, and then seamlessly switches to saturation. A comparative analysis is carried out with the experimental dependences of the thermal conductivity of ceramics (lanthanum sulfide LaS1.48).

  2. Limits on thermal variations in a dozen quiescent neutron stars over a decade

    NARCIS (Netherlands)

    Bahramian, A.; Heinke, C.O.; Degenaar, N.; Chomiuk, L.; Wijnands, R.; Strader, J.; Ho, W.C.G.; Pooley, D.

    2015-01-01

    n quiescent low-mass X-ray binaries (qLMXBs) containing neutron stars, the origin of the thermal X-ray component may be either release of heat from the core of the neutron star, or continuing low-level accretion. In general, heat from the core should be stable on time-scales <104 yr, while

  3. Limited thermal transport in rippled graphene induced by bi-axial strain for thermoelectric applications

    Science.gov (United States)

    Park, Kyeong Hyun; Ravaioli, Umberto

    2017-07-01

    Among efforts made to improve thermoelectric efficiency, the use of structurally modified graphene nanomaterials as thermoelectric matter are one of the promising strategies owing to their fascinating physical and electrical properties, and these materials are anticipated to be less thermally conductive than regular graphene structures, as a result of an additional phonon scattering introduced at the modified surfaces. In this study, we explore the thermal conductivity behaviors of strain-induced rippled graphene sheets by varying the ripple amplitude, periodicity, and dimensions of the structure. We introduce a technique which enables creation of a graphene sheet with evenly distributed ripples in molecular dynamics simulation, and the Green-Kubo linear response theory is used to calculate the thermal conductivity of the structures of interest. The results reveal the reduction of thermal conductivity with the greater degree of strain, the smaller system dimension, and the shorter ripple wavelength, which, in turn, could lead to the thermoelectric efficiency enhancement. This work has significance in that it presents the capability of generating repeated and controllable patterns in molecular dynamics, and so, it enables the atomic-level transport study in the regularly patterned two-dimensional surface or in any structures with a specified degree of strain.

  4. Temperature-Dependent Development and Thermal Sensitivity of Blaptica dubia (Blattodea: Blaberidae).

    Science.gov (United States)

    Wu, Hao; Hu, Xing Ping; Appel, Arthur G

    2017-04-01

    Temperature-dependent development of nymphs of the Dubia cockroach, Blaptica dubia Serville, was described using constant-temperature data collected from laboratory experiments at 15, 20, 25, 30, 35, and 40 °C. Simple linear regression models were developed based on the data from each instar. Degree-days required to complete a particular life stage were estimated as 457.5, 668, 1,031, 1,317, 1,515, 1,429, and 2,071 for instars 1-7, respectively. Nymphs developed to adulthood at 20, 25, and 30 °C, but all died before developing into fifth instar at 35 °C and into second instar at 40 °C. Critical thermal maximum (CTMax) and critical thermal minimum (CTMin) of B. dubia were also measured for each instar. CTMax ranged from 44.8 to 49.9 °C for fourth and second instars, respectively. CTMin ranged from approximately -2 °C for seventh instar to - 3.1 °C for second instar. There was no relationship between body mass (instar) and CTMax; however, CTMin was positively correlated with body mass. These results could be used to control the development rate of B. dubia and adjust the optimal rearing temperature for B. dubia in a given situation. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Expanded modeling of temperature-dependent dielectric properties for microwave thermal ablation.

    Science.gov (United States)

    Ji, Zhen; Brace, Christopher L

    2011-08-21

    Microwaves are a promising source for thermal tumor ablation due to their ability to rapidly heat dispersive biological tissues, often to temperatures in excess of 100 °C. At these high temperatures, tissue dielectric properties change rapidly and, thus, so do the characteristics of energy delivery. Precise knowledge of how tissue dielectric properties change during microwave heating promises to facilitate more accurate simulation of device performance and helps optimize device geometry and energy delivery parameters. In this study, we measured the dielectric properties of liver tissue during high-temperature microwave heating. The resulting data were compiled into either a sigmoidal function of temperature or an integration of the time-temperature curve for both relative permittivity and effective conductivity. Coupled electromagnetic-thermal simulations of heating produced by a single monopole antenna using the new models were then compared to simulations with existing linear and static models, and experimental temperatures in liver tissue. The new sigmoidal temperature-dependent model more accurately predicted experimental temperatures when compared to temperature-time integrated or existing models. The mean percent differences between simulated and experimental temperatures over all times were 4.2% for sigmoidal, 10.1% for temperature-time integration, 27.0% for linear and 32.8% for static models at the antenna input power of 50 W. Correcting for tissue contraction improved agreement for powers up to 75 W. The sigmoidal model also predicted substantial changes in heating pattern due to dehydration. We can conclude from these studies that a sigmoidal model of tissue dielectric properties improves prediction of experimental results. More work is needed to refine and generalize this model.

  6. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment

    Science.gov (United States)

    Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.

    2015-12-01

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events.

  7. Thermal preferences and limits of Triatoma brasiliensis in its natural environment - Field observations while host searching

    Science.gov (United States)

    Catalá, Silvia; Bezerra, Claudia Mendonça; Diotaiuti, Lileia

    2015-01-01

    The goal of this work was to explore the thermal relationship between foraging Triatoma brasiliensis and its natural habitat during the hottest season in the state of Ceará, Brazil. The thermal profiles were determined using infrared analysis. Although the daily temperature of rock surfaces varied in a wide range, T. brasiliensis selected to walk through areas with temperatures between 31.7-40.5ºC. The temperature of T. brasiliensis body surface ranged from 32.8-34.4ºC, being higher in legs than the abdomen. A strong relationship was found between the temperature of the insect and the temperature of rock crevices where they were hidden (r: 0.96, p < 0.05). The species was active at full sunlight being a clear example of how the light-dark rhythm may be altered, even under predation risk. Our results strongly suggest a thermal borderline for T. brasiliensis foraging activity near 40ºC. The simultaneous determination of insect body and rock temperatures here presented are the only obtained in natural habitats for this or other triatomines. PMID:26517659

  8. Seasonally dependent iron limitation of nitrogen fixation in tropical forests of karst landscapes

    Science.gov (United States)

    Winbourne, J. B.; Brewer, S.; Houlton, B. Z.

    2015-12-01

    Limestone tropical forests in karst topography are one of the most poorly studied ecosystems on Earth, and has been substantially cleared by human activities throughout much of Central America. This ecosystem is noted for its high level of plant productivity, biomass, endemism and biological diversity compared to nearby neighboring tropical forests on volcanic rock substrates (Brewer et al. 2002). A question remains as to how limestone tropical forests are able to maintain the high nutrient demands of plant photosynthesis and tree biomass growth. Here, we demonstrate that rates of nitrogen (N) fixation are higher in limestone versus volcanic soil substrates, with direct evidence for the emergence of seasonally dependent iron limitation of N fixation in limestone tropical forest. N fixation rates showed a three-fold increase in response to iron additions, especially during the wet season when N demands of the forest trees are highest. In contrast, adjacent forests growing on the more classical acidic volcanic soils showed no response to iron or other nutrient additions. Biologically available pools of iron were exceedingly low in the limestone forest site, consistent with the complexation of iron under high pH conditions. Biological acquisition of iron, as measured by the concentration of iron chelating compounds (i.e. siderophores), provided additional evidence for iron limitation of microbial processes in limestone tropical forests, where concentrations were six times higher than those at the volcanic site. Our results suggest that the functioning of limestone tropical forest is strongly regulated by interactions between iron, soil pH, and N cycling.

  9. Radiative characteristics of a thin solid fuel at discrete levels of pyrolysis: Angular, spectral, and thermal dependencies

    Science.gov (United States)

    Pettegrew, Richard Dale

    Numerical models of solid fuel combustion rely on accurate radiative property values to properly account for radiative heat transfer to and from the surface. The spectral properties can change significantly over the temperature range from ambient to burnout temperature. The variations of these properties are due to mass loss (as the sample pyrolyzes), chemical changes, and surface finish changes. In addition, band-integrated properties can vary due to the shift in the peak of the Planck curve as the temperature increases, which results in differing weightings of the spectral values. These effects were quantified for a thin cellulosic fuel commonly used in microgravity combustion studies (KimWipesRTM). Pyrolytic effects were simulated by heat-treating the samples in a constant temperature oven for varying times. Spectral data was acquired using a Fourier Transform Infrared (FTIR) spectrometer, along with an integrating sphere. Data was acquired at different incidence angles by mounting the samples at different angles inside the sphere. Comparisons of samples of similar area density created using different heat-treatment regimens showed that thermal history of the samples was irrelevant in virtually all spectral regions, with overall results correlating well with changes in area density. Spectral, angular, and thermal dependencies were determined for a representative data set, showing that the spectral absorptance decreases as the temperature increases, and decreases as the incidence angle varies from normal. Changes in absorptance are primarily offset by corresponding changes in transmittances, with reflectance values shown to be low over the tested spectral region of 2.50 mum to 24.93 mum. Band-integrated values were calculated as a function of temperature for the entire tested spectral region, as well as limited bands relevant for thermal imaging applications. This data was used to demonstrate the significant error that is likely if incorrect emittance values are

  10. Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Brill, J. W.; Shahi, Maryam; Yao, Y. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Payne, Marcia M.; Anthony, J. E. [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Edberg, Jesper; Crispin, Xavier [Department of Science and Technology, Organic Electronics, Linköping University, SE-601 74 Norrköping (Sweden)

    2015-12-21

    We have used a photothermal technique, in which chopped light heats the front surface of a small (∼1 mm{sup 2}) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid-nitrogen-cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light, which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side groups, carry most of the heat.

  11. CD47 limits antibody dependent phagocytosis against non-malignant B cells.

    Science.gov (United States)

    Gallagher, Sandra; Turman, Sean; Lekstrom, Kristen; Wilson, Susan; Herbst, Ronald; Wang, Yue

    2017-05-01

    Recent studies have demonstrated the importance of CD47 in protecting malignant B cells from antibody dependent cellular phagocytosis (ADCP). Combined treatment of anti-CD47 and -CD20 antibodies synergistically augment elimination of tumor B cells in xenograft mouse models. This has led to the development of novel reagents that can potentially enhance killing of malignant B cells in patients. B cell depleting therapy is also a promising treatment for autoimmune patients. In the current study, we aimed to investigate whether or not CD47 protects non-malignant B cells from ADCP. We show that CD47 is expressed on all B cells in mice, with the highest level on plasma cells in bone marrow and spleen. Although its expression is dispensable for B cell development in mice, CD47 on B cells limits antibody mediated phagocytosis. B cell depletion following in vivo anti-CD19 treatment is more efficient in CD47-/- mice than in wild type mice. In vitro, both naïve and activated B cells from CD47-/- mice are more sensitive to ADCP than wild type B cells. Lastly, we show in an ADCP assay that blocking CD47 can enhance anti-CD19 antibody mediated phagocytosis of wild type B cells. These results suggest that in addition to its already demonstrated benefit in cancer, targeting CD47 may be used as an adjunct in combination with B cell depletion antibodies for treatment of autoimmune diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 38 CFR 17.83 - Limitations on payment for alcohol and drug dependence or abuse treatment and rehabilitation.

    Science.gov (United States)

    2010-07-01

    ... for alcohol and drug dependence or abuse treatment and rehabilitation. 17.83 Section 17.83 Pensions... Agencies § 17.83 Limitations on payment for alcohol and drug dependence or abuse treatment and rehabilitation. The authority to enter into contracts shall be effective for any fiscal year only to such extent...

  13. Chirality- and thickness-dependent thermal conductivity of few-layer graphene: a molecular dynamics study

    OpenAIRE

    Zhong, Wei-rong; Zhang, Mao-Ping; Ai, Bao-quan; Zheng, Dong-Qin

    2011-01-01

    The thermal conductivity of graphene nanoribbons (layer from 1 to 8 atomic planes) is investigated by using the nonequilibrium molecular dynamics method. We present that the room-temperature thermal conductivity decays monotonically with the number of the layers in few-layer graphene. The superiority of zigzag graphene in thermal conductivity is only available in high temperature region and disappears in multi-layer case. It is explained that the phonon spectral shrink in high frequency induc...

  14. Thickness-dependent thermal conductivity of encased graphene and ultrathin graphite.

    Science.gov (United States)

    Jang, Wanyoung; Chen, Zhen; Bao, Wenzhong; Lau, Chun Ning; Dames, Chris

    2010-10-13

    The thermal conductivity of graphene and ultrathin graphite (thickness from 1 to ∼20 layers) encased within silicon dioxide was measured using a heat spreader method. The thermal conductivity increases with the number of graphene layers, approaching the in-plane thermal conductivity of bulk graphite for the thickest samples, while showing suppression below 160 W/m-K at room temperature for single-layer graphene. These results show the strong effect of the encasing oxide in disrupting the thermal conductivity of adjacent graphene layers, an effect that penetrates a characteristic distance of approximately 2.5 nm (∼7 layers) into the core layers at room temperature.

  15. Effect of electronic contribution on temperature-dependent thermal transport of antimony telluride thin film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won-Yong; Park, No-Won [Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Hong, Ji-Eun [Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Yoon, Soon-Gil, E-mail: sgyoon@cnu.ac.kr [Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Koh, Jung-Hyuk [School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Lee, Sang-Kwon, E-mail: sangkwonlee@cau.ac.kr [Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of)

    2015-01-25

    Highlights: • We investigated thermal transport of the antimony telluride thin films. • The contribution of the electronic thermal conductivity increased up to ∼77% at 300 K. • We theoretically analyze and explain the high contribution of electronic component. - Abstract: We study the theoretical and experimental characteristics of thermal transport of 100 nm and 500 nm-thick antimony telluride (Sb{sub 2}Te{sub 3}) thin films prepared by radio frequency magnetron sputtering. The thermal conductivity was measured at temperatures ranging from 20 to 300 K, using four-point-probe 3-ω method. Out-of-plane thermal conductivity of the Sb{sub 2}Te{sub 3} thin film was much lesser in comparison to the bulk material in the entire temperature range, confirming that the phonon- and electron-boundary scattering are enhanced in thin films. Moreover, we found that the contribution of the electronic thermal conductivity (κ{sub e}) in total thermal conductivity (κ) linearly increased up to ∼77% at 300 K with increasing temperature. We theoretically analyze and explain the high contribution of electronic component of thermal conductivity towards the total thermal conductivity of the film by a modified Callaway model. Further, we find the theoretical model predictions to correspond well with the experimental results.

  16. Direct thermal effects of the Hadean bombardment did not limit early subsurface habitability

    Science.gov (United States)

    Grimm, R. E.; Marchi, S.

    2018-03-01

    Intense bombardment is considered characteristic of the Hadean and early Archean eons, yet some detrital zircons indicate that near-surface water was present and thus at least intervals of clement conditions may have existed. We investigate the habitability of the top few kilometers of the subsurface by updating a prior approach to thermal evolution of the crust due to impact heating, using a revised bombardment history, a more accurate thermal model, and treatment of melt sheets from large projectiles (>100 km diameter). We find that subsurface habitable volume grows nearly continuously throughout the Hadean and early Archean (4.5-3.5 Ga) because impact heat is dissipated rapidly compared to the total duration and waning strength of the bombardment. Global sterilization was only achieved using an order of magnitude more projectiles in 1/10 the time. Melt sheets from large projectiles can completely resurface the Earth several times prior to ∼4.2 Ga but at most once since then. Even in the Hadean, melt sheets have little effect on habitability because cooling times are short compared to resurfacing intervals, allowing subsurface biospheres to be locally re-established by groundwater infiltration between major impacts. Therefore the subsurface is always habitable somewhere, and production of global steam or silicate-vapor atmospheres are the only remaining avenues to early surface sterilization by bombardment.

  17. Analysis for fin efficiency with temperature-dependent thermal conductivity of fractional order energy balance equation using HPST Method

    Directory of Open Access Journals (Sweden)

    A. Patra

    2016-03-01

    Full Text Available Radiating extended surfaces are usually utilized to enhance the heat transfer between primary surface and the environment. In this paper, temperature distribution, fin efficiency, efficacy of convective straight fins with constant and temperature-dependent thermal conductivity are solved by implementing homotopy perturbation sumudu transform method (HPSTM. The proposed method is very useful and practical for solving the fractional order nonlinear diffusion equation, which is associated with variable thermal conductivity condition. A dimensionless analytical expression has been developed for fin effectiveness. The fin efficiency and the fin effectiveness have been attained as a function of thermo-geometric fin parameter. It can be noticed that the thermal conductivity parameter has a strong influence over the fin efficiency. The analytical solutions acquired by the present method illustrate the approach is easy to implement and computationally very interesting. The obtained results are compared with previously found classical order results using variational iteration method (VIM, Adomian decomposition method, and the results from Galerkin method in order to show the competence of this present method. HPSTM is a simple and effective method for rapid assessment of physical systems although the fractional order energy balance equations comprise with strong nonlinear terms. The subsequent correlation equations can benefit thermal design engineers for designing of innovative straight fins with both constant and temperature-dependent thermal conductivity.

  18. Physiological thermal limits predict differential responses of bees to urban heat-island effects.

    Science.gov (United States)

    Hamblin, April L; Youngsteadt, Elsa; López-Uribe, Margarita M; Frank, Steven D

    2017-06-01

    Changes in community composition are an important, but hard to predict, effect of climate change. Here, we use a wild-bee study system to test the ability of critical thermal maxima (CTmax, a measure of heat tolerance) to predict community responses to urban heat-island effects in Raleigh, NC, USA. Among 15 focal species, CTmax ranged from 44.6 to 51.3°C, and was strongly predictive of population responses to urban warming across 18 study sites (r(2) = 0.44). Species with low CTmax declined the most. After phylogenetic correction, solitary species and cavity-nesting species (bumblebees) had the lowest CTmax, suggesting that these groups may be most sensitive to climate change. Community responses to urban and global warming will likely retain strong physiological signal, even after decades of warming during which time lags and interspecific interactions could modulate direct effects of temperature. © 2017 The Author(s).

  19. Limited role for thermal erosion by turbulent lava in proximal Athabasca Valles, Mars

    Science.gov (United States)

    Cataldo, Vincenzo; Williams, David A.; Dundas, Colin M.; Kestay, Laszlo P.

    2015-01-01

    The Athabasca Valles flood lava is among the most recent (Mars and was probably emplaced turbulently. The Williams et al. (2005) model of thermal erosion by lava has been applied to what we term “proximal Athabasca,” the 75 km long upstream portion of Athabasca Valles. For emplacement volumes of 5000 and 7500 km3and average flow thicknesses of 20 and 30 m, the duration of the eruption varies between ~11 and ~37 days. The erosion of the lava flow substrate is investigated for three eruption temperatures (1270°C, 1260°C, and 1250°C), and volatile contents equivalent to 0–65 vol % bubbles. The largest erosion depths of ~3.8–7.5 m are at the lava source, for 20 m thick and bubble-free flows that erupted at their liquidus temperature (1270°C). A substrate containing 25 vol % ice leads to maximum erosion. A lava temperature 20°C below liquidus reduces erosion depths by a factor of ~2.2. If flow viscosity increases with increasing bubble content in the lava, the presence of 30–50 vol % bubbles leads to erosion depths lower than those relative to bubble-free lava by a factor of ~2.4. The presence of 25 vol % ice in the substrate increases erosion depths by a factor of 1.3. Nevertheless, modeled erosion depths, consistent with the emplacement volume and flow duration constraints, are far less than the depth of the channel (~35–100 m). We conclude that thermal erosion does not appear to have had a major role in excavating Athabasca Valles.

  20. Length-dependent thermal conductivity in suspended single-layer graphene.

    Science.gov (United States)

    Xu, Xiangfan; Pereira, Luiz F C; Wang, Yu; Wu, Jing; Zhang, Kaiwen; Zhao, Xiangming; Bae, Sukang; Tinh Bui, Cong; Xie, Rongguo; Thong, John T L; Hong, Byung Hee; Loh, Kian Ping; Donadio, Davide; Li, Baowen; Özyilmaz, Barbaros

    2014-04-16

    Graphene exhibits extraordinary electronic and mechanical properties, and extremely high thermal conductivity. Being a very stable atomically thick membrane that can be suspended between two leads, graphene provides a perfect test platform for studying thermal conductivity in two-dimensional systems, which is of primary importance for phonon transport in low-dimensional materials. Here we report experimental measurements and non-equilibrium molecular dynamics simulations of thermal conduction in suspended single-layer graphene as a function of both temperature and sample length. Interestingly and in contrast to bulk materials, at 300 K, thermal conductivity keeps increasing and remains logarithmically divergent with sample length even for sample lengths much larger than the average phonon mean free path. This result is a consequence of the two-dimensional nature of phonons in graphene, and provides fundamental understanding of thermal transport in two-dimensional materials.

  1. Exploring the Thermal Limits of IR-Based Automatic Whale Detection (ETAW)

    Science.gov (United States)

    2015-09-30

    during naval exercises and offshore seismic surveys may be harmful to marine mammals, have led an increasing number of regulating agencies to request...publication in preparation) which however depends on increased computational power, prohibiting its implementation in Matlab ™ but requiring the

  2. Thermal niche of Atlantic cod Gadus morhua: limits, tolerance and optima

    DEFF Research Database (Denmark)

    Righton, David A.; Andersen, Ken Haste; Neat, Francis

    2010-01-01

    Recent studies in the marine environment have suggested that the limited phenotypic plasticity of cold-adapted species such as Atlantic cod Gadus morhua L. will cause distributions to shift toward the poles in response to rising sea temperatures. Some cod stocks are predicted to collapse, but thi...

  3. Fatigue limit by thermal analysis of specimen surface in mono axial traction test

    Science.gov (United States)

    Risitano, A.; Giacomo, R.; Clienti, C.

    2010-06-01

    In this work is indicated how it could be possible to evaluate the limit stress of the thermo-elastic phase of deformation by thermo-analysing the surface of the specimen during a static traction test. Adding the temperature curve measured on a small area of the surface (the hottest) to the classic stress-strain curve, it is possible to evaluate a limit temperature T0 coincident with the beginning of the non linear trend of the curve. The corresponding stress value is coincident with the fatigue limit of the analyzed component. As an example, the results of traction tests performed on two notched specimens, where the change of linearity in the temperature curve during static traction test was evident, are reported. The corresponding value of stress was a good approximation of the fatigue limit for R = - 1, determined by the conventional method. The aim of the reported examples in this paper must be interpreted as support to the basic principle of the method and not as the results of a complete experimental planning of which we will comment in an another occasion.

  4. Fatigue limit by thermal analysis of specimen surface in mono axial traction test

    Directory of Open Access Journals (Sweden)

    Clienti C.

    2010-06-01

    Full Text Available In this work is indicated how it could be possible to evaluate the limit stress of the thermo-elastic phase of deformation by thermo-analysing the surface of the specimen during a static traction test. Adding the temperature curve measured on a small area of the surface (the hottest to the classic stress-strain curve, it is possible to evaluate a limit temperature T0 coincident with the beginning of the non linear trend of the curve. The corresponding stress value is coincident with the fatigue limit of the analyzed component. As an example, the results of traction tests performed on two notched specimens, where the change of linearity in the temperature curve during static traction test was evident, are reported. The corresponding value of stress was a good approximation of the fatigue limit for R = - 1, determined by the conventional method. The aim of the reported examples in this paper must be interpreted as support to the basic principle of the method and not as the results of a complete experimental planning of which we will comment in an another occasion.

  5. Phonon and electron mean free path dependent contributions to thermal conductivity in crystalline materials and thermal interface conductance across metal alloy-dielectric interfaces

    Science.gov (United States)

    Freedman, Justin P.

    Electronic and optical devices continue to decrease in size year after year. Today, devices feature length scales that are commensurate to energy carrier mean free paths. As a result, the physical principles that govern their operation and energy transport processes continue to dramatically change. This work aims to understand the nanoscale thermal transport processes in crystalline materials and across metal-dielectric interfaces. Solid-state devices, such as light emitting diodes (LED) and high power electronics, are replacing older technologies, such as incandescent and fluorescent lighting. Nitride-based semiconductors are the primary material candidates to replace these older technologies, in part because of their high thermal conductivity. In Chapter 2, the phonon mean free path dependent contributions to thermal conductivity in LED-based materials are presented. Using high frequency surface temperature modulation that generates nondiffusive phonon transport the phonon mean free path spectra of GaAs, GaN, AlN, and 4H-SiC at temperatures near 80 K, 150 K, 300 K, and 400 K are shown. This work demonstrates that phonons with mean free paths greater than 230 +/- 120 nm, 1000 +/- 200 nm, 2500 +/- 800 nm, and 4200 +/- 850 nm contribute ˜50% of the bulk thermal conductivity of GaAs, GaN, AlN, and 4H-SiC near room temperature. By nondimensionalizing the data based on Umklapp scattering rates of phonons, a universal phonon mean free path spectrum in small unit cell crystalline semiconductors at high temperature is identified. In Chapter 3, a theoretical framework based on the electron-phonon coupled Boltzmann transport equations (BTEs) is presented for the interpretation of nondiffusive thermal conductivity measurements in gold made via frequency domain thermoreflectance (FDTR). The thermal conductivity of a bulk gold crystal was measured over a temperature range of 23 K to 304 K as a function of FDTR's laser spot size. Through comparison of an analytical solution to

  6. The Effects of Thermal Radiation on an Unsteady MHD Axisymmetric Stagnation-Point Flow over a Shrinking Sheet in Presence of Temperature Dependent Thermal Conductivity with Navier Slip.

    Science.gov (United States)

    Mondal, Sabyasachi; Haroun, Nageeb A H; Sibanda, Precious

    2015-01-01

    In this paper, the magnetohydrodynamic (MHD) axisymmetric stagnation-point flow of an unsteady and electrically conducting incompressible viscous fluid in with temperature dependent thermal conductivity, thermal radiation and Navier slip is investigated. The flow is due to a shrinking surface that is shrunk axisymmetrically in its own plane with a linear velocity. The magnetic field is imposed normally to the sheet. The model equations that describe this fluid flow are solved by using the spectral relaxation method. Here, heat transfer processes are discussed for two different types of wall heating; (a) a prescribed surface temperature and (b) a prescribed surface heat flux. We discuss and evaluate how the various parameters affect the fluid flow, heat transfer and the temperature field with the aid of different graphical presentations and tabulated results.

  7. Attaining the rate-independent limit of a rate-dependent strain gradient plasticity theory

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2016-01-01

    The existence of characteristic strain rates in rate-dependent material models, corresponding to rate-independent model behavior, is studied within a back stress based rate-dependent higher order strain gradient crystal plasticity model. Such characteristic rates have recently been observed...... rates for a selected quantity are identified through numerical analysis. Evidently, the concept of a characteristic rate, within the rate-dependent material models, may help unlock an otherwise inaccessible parameter space....

  8. Pushing desalination recovery to the maximum limit: Membrane and thermal processes integration

    KAUST Repository

    Shahzad, Muhammad Wakil

    2017-05-05

    The economics of seawater desalination processes has been continuously improving as a result of desalination market expansion. Presently, reverse osmosis (RO) processes are leading in global desalination with 53% share followed by thermally driven technologies 33%, but in Gulf Cooperation Council (GCC) countries their shares are 42% and 56% respectively due to severe feed water quality. In RO processes, intake, pretreatment and brine disposal cost 25% of total desalination cost at 30–35% recovery. We proposed a tri-hybrid system to enhance overall recovery up to 81%. The conditioned brine leaving from RO processes supplied to proposed multi-evaporator adsorption cycle driven by low temperature industrial waste heat sources or solar energy. RO membrane simulation has been performed using WinFlow and IMSDesign commercial softwares developed by GE and Nitto. Detailed mathematical model of overall system is developed and simulation has been conducted in FORTRAN. The final brine reject concentration from tri-hybrid cycle can vary from 166,000ppm to 222,000ppm if RO retentate concentration varies from 45,000ppm to 60,000ppm. We also conducted economic analysis and showed that the proposed tri-hybrid cycle can achieve highest recovery, 81%, and lowest energy consumption, 1.76kWhelec/m3, for desalination reported in the literature up till now.

  9. Limits and Optimization of Power Input or Output of Actual Thermal Cycles

    OpenAIRE

    Emin Açıkkalp; Hasan Yamık

    2013-01-01

    In classical thermodynamic, maximum power obtained from system (or minimum power supplied to system) defined as availability (exergy), but availability term is only used for reversible systems. In reality, there is no reversible system, all systems are irreversible, because reversible cycles doesn’t include constrains like time or size and they operates in quasi-equilibrium state. Purpose of this study is to define limits of the all basic thermodynamic cycles and to provide finite-time exergy...

  10. The Limit Behavior of a Stochastic Logistic Model with Individual Time-Dependent Rates

    Directory of Open Access Journals (Sweden)

    Yilun Shang

    2013-01-01

    Full Text Available We investigate a variant of the stochastic logistic model that allows individual variation and time-dependent infection and recovery rates. The model is described as a heterogeneous density dependent Markov chain. We show that the process can be approximated by a deterministic process defined by an integral equation as the population size grows.

  11. Moisture dependent thermal properties of hydrophilic mineral wool: application of the effective media theory

    National Research Council Canada - National Science Library

    Iñigo Antepara

    2015-01-01

    .... Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly...

  12. Layer and size dependence of thermal conductivity in multilayer graphene nanoribbons

    OpenAIRE

    Cao, Hai-Yuan; Guo, Zhi-Xin; Xiang, Hongjun; Gong, Xin-Gao

    2011-01-01

    Using non-equilibrium molecular dynamics method(NEMD), we have found that the thermal conductivity of multilayer graphene nanoribbons monotonously decreases with the increase of the number of layers, such behavior can be attributed to the phonon resonance effect of out-of-plane phonon modes. The reduction of thermal conductivity is found to be proportional to the layer size, which is caused by the increase of phonon resonance. Our results are in agreement with recent experiment on dimensional...

  13. Magnetic field dependent thermal conductance in La0.67Ca0.33MnO3

    Science.gov (United States)

    Euler, C.; Hołuj, P.; Talkenberger, A.; Jakob, G.

    2015-05-01

    Using the differential 3 ω technique we measured the low-temperature out-of-plane thermal conductance of heteroepitaxial thin film La0.67Ca0.33MnO3 (LCMO). The magnetic field dependence of the thermal conductance reached values of up to 23%. The effect was observed to be largest in the vicinity of the metal-insulator transition, since the enhancement in thermal conductance is triggered by the colossal magnetoresistance effect increasing the electronic contribution to the thermal conductance. The point of the maximal change was adjusted by post-annealing the samples in an oxygen atmosphere. Samples with a higher transition temperature and lower epitaxial strain displayed a lower magnetic field dependence of up to 8% of the zero-field value. While the samples with a low strain state seemingly obeyed the Wiedemann-Franz law, those under high strain did not. Raman spectroscopy was applied to explain this discrepancy by an enhanced phononic density of states caused by rotational distortions of the unit cell. Our results show that in systems with strong electron-lattice interaction manipulation of the phonon spectrum is possible by magnetic fields.

  14. CALCULATED TEMPERATURE RISE AND THERMAL ELONGATION OF STRUCTURAL COMPONENTS, DEPENDING ON ACTION INTEGRAL OF INJECTED LIGHTNING CURRENTS

    DEFF Research Database (Denmark)

    Madsen, Søren Find

    2005-01-01

    In the initial phase of an aircraft design, it is valuable to be capable of predicting temperature rise and thermal elongation depending on the actual threat from lightning currents. In this paper equations are stated to calculate the temperature rise of different structures. The analytical...... expressions established, accounts for the geometry of the structure (round conductor, rectangular cross section, pipe, plane sheet, etc), the material properties (Aluminum, Copper, Carbon Fiber Composites, etc.), the frequency of the current (skin depth) and the Specific Energy (Action Integral). For linear...... structures (wires, bars etc.), the result is the resistance of the structure, the final temperature, and the thermal elongation depending on geometry and material properties. Regarding arc injection in the centre of plane specimens the equations enables calculation of the temperature as a function...

  15. Temperature dependency of the thermal conductivity of porous heat storage media

    Science.gov (United States)

    Hailemariam, Henok; Wuttke, Frank

    2017-10-01

    Analyzing the variation of thermal conductivity with temperature is vital in the design and assessment of the efficiency of sensible heat storage systems. In this study, the temperature variation of the thermal conductivity of a commercial cement-based porous heat storage material named - Füllbinder L is analyzed in saturated condition in the temperature range between 20 to 70°C (water based storage) with a steady state thermal conductivity and diffusivity meter. A considerable decrease in the thermal conductivity of the saturated sensible heat storage material upon increase in temperature is obtained, resulting in a significant loss of system efficiency and slower loading/un-loading rates, which when unaccounted for can lead to the under-designing of such systems. Furthermore, a new empirical prediction model for the estimation of thermal conductivity of cement-based porous sensible heat storage materials and naturally occurring crystalline rock formations as a function of temperature is proposed. The results of the model prediction are compared with the experimental results with satisfactory results.

  16. A note on the almost sure central limit theorems for the maxima of strongly dependent nonstationary Gaussian vector sequences

    Directory of Open Access Journals (Sweden)

    Xiang Zeng

    2016-06-01

    Full Text Available Abstract We prove some almost sure central limit theorems for the maxima of strongly dependent nonstationary Gaussian vector sequences under some mild conditions. The results extend the ASCLT to nonstationary Gaussian vector sequences and give substantial improvements for the weight sequence obtained by Lin et al. (Comput. Math. Appl. 62(2:635-640, 2011.

  17. Experimental and numerical determination of thermal forming limit diagrams (TFLD) of high strength steel 22MnB5

    Science.gov (United States)

    Shi, D. Y.; Ying, L.; Hu, P.; Lu, J. D.; Zhao, X.; Liu, W. Q.

    2013-05-01

    High strength steel components are increasingly being considered for use in vehicle structures due to the potential for higher strength to weight ratio, fuel economy improvement and emission reduction. However, high strength steel's poor ductility at room temperature requires sheet forming to be carried out in hot forming method. The Thermal Forming Limit Diagram (TFLD) is an important primary criterion to determine how close the sheet metal is to tearing when it is formed into a product shape in hot forming process. In this work, an efficient experimental set-up named TFLD 300 which is based on Nakajima test has been developed. Several experiments for hot forming limits of high strength steel 22MnB5 were performed and the forming limit curves at different temperatures are obtained. Then the three-dimensional TFLD which considers temperature history and strain path is constructed. As an evaluation criterion for formability, the three-dimensional TFLD is introduced into KMAS (King Mesh Analysis System), which is independently developed commercial CAE software and can be used for hot forming simulation. Subsequently, a typical B-pillar's hot forming process with varying process conditions have been simulated by using the KMAS software. And the corresponding experiment results confirm that the KMAS software and three-dimensional TFLD can accurately predict the fracture of sheet metal in hot forming.

  18. Spin-dependent WIMP-nucleon cross section limits from first data of PandaX-II experiment

    CERN Document Server

    Fu, Changbo; Zhou, Xiaopeng; Chen, Xun; Chen, Yunhua; Fang, Deqing; Giboni, Karl; Giuliani, Franco; Han, Ke; Huang, Xingtao; Ji, Xiangdong; Ju, Yonglin; Lei, Siao; Li, Shaoli; Liu, Huaxuan; Liu, Jianglai; Ma, Yugang; Mao, Yajun; Ren, Xiangxiang; Tan, Andi; Wang, Hongwei; Wang, Jiming; Wang, Meng; Wang, Qiuhong; Wang, Siguang; Wang, Xuming; Wang, Zhou; Wu, Shiyong; Xiao, Mengjiao; Xie, Pengwei; Yan, Binbin; Yang, Yong; Yue, Jianfeng; Zhang, Hongguang; Zhang, Tao; Zhao, Li; Zhou, Ning

    2016-01-01

    We report new constrains on the spin-dependent WIMP-neutron and WIMP-proton cross sections using recently released data from the PandaX-II experiment, a dual phase liquid xenon dark matter experiment at the China JinPing Underground Laboratory, with a total exposure of 3.3$\\times10^4$ kg-day. Assuming a standard axial-vector spin-dependent WIMP interaction with $^{129}$Xe and $^{131}$Xe nuclei, the most stringent upper limits on WIMP-neutron cross sections for WIMPs with masses above 10 GeV/c$^{2}$ are set in all direct detection experiments, with a minimum upper limit of $4.1\\times 10^{-41}$ cm$^2$ at 90\\% confidence level for a WIMP mass of 40 GeV/c$^{2}$, representing more than a factor of two improvement on the best available limits at high masses.

  19. Temperature-dependent thermal conductivity and viscosity of synthesized α-alumina nanofluids

    Science.gov (United States)

    Shah, Janki; Ranjan, Mukesh; Davariya, Vipul; Gupta, Sanjeev K.; Sonvane, Yogesh

    2017-10-01

    In the present work, we focused on the thermal conductivity and viscosity of the synthesis as well as characterize metal oxide α-Al2O3 nanoparticles suspended in distilled water:ethylene glycol (60:40) ratio based stable colloidal nanofluid. The band gap of the α-Al2O3 with and without surfactant is 4.42 and 4.59 eV, respectively. The results show that nanoparticle with polyvinyl alcohol surfactant has smaller crystalline size ( 23 nm) than without surfactant ( 36 nm). The synthesized nanofluids have good stability after 15 days of synthesis which is characterized by zeta potential analyzer. Thermal conductivity and viscosity are measured for 0.1 and 0.5 wt% concentration of alumina for with and without surfactant. The concentration of particles and added surfactant are responsible for stable fluid, thermal conductivity enhancement, and viscosity of nanofluid with respect to temperature. Therefore, the novel combinations of characterized properties of α-Al2O3 nanofluid has proved to be the best thermally stable heat transfer fluid compared to conventional cooling fluids.

  20. Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H{sub 2}O and D{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, S.N.

    1966-04-15

    The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H{sub 2}O and D{sub 2}O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H{sub 2}O and D{sub 2}O. The bound models of Nelkin for H{sub 2}O and of Butler for D{sub 2}O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D{sub 2}O than of the Nelkin model with H{sub 2}O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H{sub 2}O and D{sub 2}O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the

  1. Limits on transverse momentum dependent evolution from semi-inclusive deep inelastic scattering at moderate Q

    Science.gov (United States)

    Aidala, C. A.; Field, B.; Gamberg, L. P.; Rogers, T. C.

    2014-05-01

    In the QCD evolution of transverse momentum dependent parton distribution and fragmentation functions, the Collins-Soper evolution kernel includes both a perturbative short-distance contribution and a large-distance nonperturbative, but strongly universal, contribution. In the past, global fits, based mainly on larger Q Drell-Yan-like processes, have found substantial contributions from nonperturbative regions in the Collins-Soper evolution kernel. In this article, we investigate semi-inclusive deep inelastic scattering measurements in the region of relatively small Q, of the order of a few GeV, where sensitivity to nonperturbative transverse momentum dependence may become more important or even dominate the evolution. Using recently available deep inelastic scattering data from the COMPASS experiment, we provide estimates of the regions of coordinate space that dominate in transverse momentum dependent (TMD) processes when the hard scale is of the order of only a few GeV. We find that distance scales that are much larger than those commonly probed in large Q measurements become important, suggesting that the details of nonperturbative effects in TMD evolution are especially significant in the region of intermediate Q. We highlight the strongly universal nature of the nonperturbative component of evolution and its potential to be tightly constrained by fits from a wide variety of observables that include both large and moderate Q. On this basis, we recommend detailed treatments of the nonperturbative component of the Collins-Soper evolution kernel for future TMD studies.

  2. FORTRAN 77 programs for conductive cooling of dikes with temperature-dependent thermal properties and heat of crystallization

    Science.gov (United States)

    Delaney, P.T.

    1988-01-01

    Temperature histories obtained from transient heat-conduction theory are applicable to most dikes despite potential complicating effects related to magma flow during emplacement, groundwater circulation, and metamorphic reaction during cooling. Here. machine-independent FORTRAN 77 programs are presented to calculate temperatures in and around dikes as they cool conductively. Analytical solutions can treat thermal-property contrasts between the dike and host rocks, but cannot address the release of magmatic heat of crystallization after the early stages of cooling or the appreciable temperature dependence of thermal conductivity and diffusivity displayed by most rock types. Numerical solutions can incorporate these additional factors. The heat of crystallization can raise the initial temperature at the dike contact, ??c1, about 100??C above that which would be estimated if it were neglected, and can decrease the rate at which the front of solidified magma moves to the dike center by a factor of as much as three. Thermal conductivity and diffusivity of rocks increase with decreasing temperature and, at low temperatures, these properties increase more if the rocks are saturated with water. Models that treat these temperature dependencies yield estimates of ??c1 that are as much as 75??C beneath those which would be predicted if they were neglected. ?? 1988.

  3. The time-dependent 3D discrete ordinates code TORT-TD with thermal-hydraulic feedback by ATHLET models

    Energy Technology Data Exchange (ETDEWEB)

    Seubert, A.; Velkov, K.; Langenbuch, S. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Forschungsinstitute, D-85748 Garching (Germany)

    2008-07-01

    This paper describes the time-dependent 3D discrete ordinates transport code TORT-TD. Thermal-hydraulic feedback is considered by coupling TORT-TD with the thermal-hydraulics system code ATHLET. The coupled code TORT-TD/ATHLET allows 3D pin-by-pin analyses of transients in few energy groups and anisotropic scattering by solving the time-dependent transport equation using the unconditionally stable implicit method. The nuclear cross sections are interpolated between pre-calculated table values of fuel temperature, moderator density and boron concentration. For verification of the implementation, selected test cases have been calculated by TORT-TD/ATHLET. They include a control rod ejection transient in a small PWR fuel assembly arrangement and a local boron concentration change in a single PWR fuel assembly. In the latter, special attention has been paid to study the influence of the thermal-hydraulic feedback modelling in ATHLET. The results obtained for a control rod ejection accident in a PWR quarter core demonstrate the applicability of TORT-TD/ATHLET. (authors)

  4. An active power dispatch technique using pseudo spot price of electricity for a power system area including limited energy supply thermal units

    Energy Technology Data Exchange (ETDEWEB)

    Fadil, Salih [Osmangazi Univ., Dept. of Electrical Engineering, Eskisehir (Turkey); Yasar, Celal [Dumlupnar Univ., Dept. of Electrical Engineering, Kutahya (Turkey)

    2002-02-01

    We propose a new active power dispatch technique using pseudo spot price of electricity for a power system area including limited energy supply thermal units. The dispatch technique considers upper and lower generation limits of the generation units, maximum capability of transmission lines and the fuel constraint of the limited energy supply thermal units in a lossy power system. Calculation of active line flows that are used in the determination of optimal active generations are obtained by means of Newton-Raphson AC load flow calculation. We assume that limited energy supply thermal units are fueled under take-or-pay agreement. The proposed dispatch technique was tested on an example power system. The dispatch problem was also solved by means of another dispatch technique that uses gradient method. Results obtained from both techniques are compared. (Author)

  5. Central limit theorems for sequences with m(n)-dependent main part

    NARCIS (Netherlands)

    Nieuwenhuis, G.

    1992-01-01

    Let (Xi(n); n ϵ N, 1⩽i⩽h(n)) be a double sequence of random variables with h(n)→∞ as n→∞. Suppose that the sequence can be split into two parts: an m(n)-dependent sequence (Xi,m(n); n ϵ N, 1⩽i⩽h(n)) of main terms and a sequence (Xi,m(n); n ϵ N, 1⩽i⩽h(n)) of residual terms. Here (m(n)) may be

  6. Shape Dependent Thermal Conductivity of TiO2-Deionized Water and Ethylene Glycol Dispersion.

    Science.gov (United States)

    Pal, Bhupender; Mallick, Soumya Suddha; Pal, Bonamali

    2015-05-01

    This paper presents the importance of different shapes and crystal phases of TiO2 nanostructures such as TiO2 P-25 (70:30 anatase and rutile), as-prepared nanorods (pure anatase) and sodium titanate nanotubes (orthorhombic Na2Ti2O5 x H2O crystal) on the thermal conductivity of de-ionized water and ethylene glycol. It revealed that TiO2 nanorods (L x W = 81-134 nm x 8-13 nm and surface area = 79 m2 g(-1)) showed always higher thermal conductivity than porous nanotubes (L x W = 85-115 nm x 9-12 nm and surface area = 176 m2 g(-1)) and commercial TiO2 P-25 (30-55 nm surface area = 56 m2 g(-1)), which was explained by their differences in crystallinity, crystal phases, compactness, surface exposed atoms, surface area and much greater mean free path of longitudinal phonon vibrations along its lateral dimensions. The subsequent effect of sonication time from 5-10 h results into the breakdown of TiO2 nanorods cluster (42 to 28 nm) with the instantaneous increase in negative zeta potential values from -31 to -45 mV, respectively, seems to be an additional cause for enhancement in its thermal conductivity.

  7. Reactive Neutrophil Responses Dependent on the Receptor Tyrosine Kinase c-MET Limit Cancer Immunotherapy.

    Science.gov (United States)

    Glodde, Nicole; Bald, Tobias; van den Boorn-Konijnenberg, Debby; Nakamura, Kyohei; O'Donnell, Jake S; Szczepanski, Sabrina; Brandes, Maria; Eickhoff, Sarah; Das, Indrajit; Shridhar, Naveen; Hinze, Daniel; Rogava, Meri; van der Sluis, Tetje C; Ruotsalainen, Janne J; Gaffal, Evelyn; Landsberg, Jennifer; Ludwig, Kerstin U; Wilhelm, Christoph; Riek-Burchardt, Monika; Müller, Andreas J; Gebhardt, Christoffer; Scolyer, Richard A; Long, Georgina V; Janzen, Viktor; Teng, Michele W L; Kastenmüller, Wolfgang; Mazzone, Massimiliano; Smyth, Mark J; Tüting, Thomas; Hölzel, Michael

    2017-10-17

    Inhibitors of the receptor tyrosine kinase c-MET are currently used in the clinic to target oncogenic signaling in tumor cells. We found that concomitant c-MET inhibition promoted adoptive T cell transfer and checkpoint immunotherapies in murine cancer models by increasing effector T cell infiltration in tumors. This therapeutic effect was independent of tumor cell-intrinsic c-MET dependence. Mechanistically, c-MET inhibition impaired the reactive mobilization and recruitment of neutrophils into tumors and draining lymph nodes in response to cytotoxic immunotherapies. In the absence of c-MET inhibition, neutrophils recruited to T cell-inflamed microenvironments rapidly acquired immunosuppressive properties, restraining T cell expansion and effector functions. In cancer patients, high serum levels of the c-MET ligand HGF correlated with increasing neutrophil counts and poor responses to checkpoint blockade therapies. Our findings reveal a role for the HGF/c-MET pathway in neutrophil recruitment and function and suggest that c-MET inhibitor co-treatment may improve responses to cancer immunotherapy in settings beyond c-MET-dependent tumors. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Limits on Momentum-Dependent Asymmetric Dark Matter with CRESST-II.

    Science.gov (United States)

    Angloher, G; Bento, A; Bucci, C; Canonica, L; Defay, X; Erb, A; Feilitzsch, F V; Ferreiro Iachellini, N; Gorla, P; Gütlein, A; Hauff, D; Jochum, J; Kiefer, M; Kluck, H; Kraus, H; Lanfranchi, J-C; Loebell, J; Münster, A; Pagliarone, C; Petricca, F; Potzel, W; Pröbst, F; Reindl, F; Schäffner, K; Schieck, J; Schönert, S; Seidel, W; Stodolsky, L; Strandhagen, C; Strauss, R; Tanzke, A; Trinh Thi, H H; Türkoğlu, C; Uffinger, M; Ulrich, A; Usherov, I; Wawoczny, S; Willers, M; Wüstrich, M; Zöller, A

    2016-07-08

    The usual assumption in direct dark matter searches is to consider only the spin-dependent or spin-independent scattering of dark matter particles. However, especially in models with light dark matter particles O(GeV/c^{2}), operators which carry additional powers of the momentum transfer q^{2} can become dominant. One such model based on asymmetric dark matter has been invoked to overcome discrepancies in helioseismology and an indication was found for a particle with a preferred mass of 3  GeV/c^{2} and a cross section of 10^{-37}  cm^{2}. Recent data from the CRESST-II experiment, which uses cryogenic detectors based on CaWO_{4} to search for nuclear recoils induced by dark matter particles, are used to constrain these momentum-dependent models. The low energy threshold of 307 eV for nuclear recoils of the detector used, allows us to rule out the proposed best fit value above.

  9. Simple frequency-dependent tools for analysis of inherent control limitations

    Directory of Open Access Journals (Sweden)

    Sigurd Skogestad

    1991-10-01

    Full Text Available By a plant's inherent control limitations we mean the characteristics of the plant which will cause poor control performance irrespective of what controller is used. Another frequently used term is 'dynamic resilience' which is the best closed-loop performance achievable using any controller. Since a plant's dynamic resilience cannot be altered by change of the control algorithm, but only by design modifications, it follows that the term controllability provides a link between process design and process control. In this paper we focus on two aspects of controllability. The plants' sensitivity to disturbances and the limitations imposed by interactions when using decentralized control. We use simple tools such as the RGA, the PRGA (Performance RGA and the closely related Closed Loop Disturbance Gain (CLDG. For example, if kth column of the CLDG is large, then this indicates that disturbance k will be difficult to reject. This may pinpoint the need for modifying the process. The PRGA provides a measure of interaction which also includes one-way coupling. In the paper we apply these measures to distillation column control and fluid catalytic cracker (FCC control.

  10. Simple voltage-controlled current source for wideband electrical bioimpedance spectroscopy: circuit dependences and limitations

    Science.gov (United States)

    Seoane, F.; Macías, R.; Bragós, R.; Lindecrantz, K.

    2011-11-01

    In this work, the single Op-Amp with load-in-the-loop topology as a current source is revisited. This circuit topology was already used as a voltage-controlled current source (VCCS) in the 1960s but was left unused when the requirements for higher frequency arose among the applications of electrical bioimpedance (EBI). The aim of the authors is not only limited to show that with the currently available electronic devices it is perfectly viable to use this simple VCCS topology as a working current source for wideband spectroscopy applications of EBI, but also to identify the limitations and the role of each of the circuit components in the most important parameter of a current for wideband applications: the output impedance. The study includes the eventual presence of a stray capacitance and also an original enhancement, driving with current the VCCS. Based on the theoretical analysis and experimental measurements, an accurate model of the output impedance is provided, explaining the role of the main constitutive elements of the circuit in the source's output impedance. Using the topologies presented in this work and the proposed model, any electronic designer can easily implement a simple and efficient current source for wideband EBI spectroscopy applications, e.g. in this study, values above 150 kΩ at 1 MHz have been obtained, which to the knowledge of the authors are the largest values experimentally measured and reported for a current source in EBI at this frequency.

  11. Concentration dependence of the optical limiting and nonlinear light scattering in aqueous suspensions of detonation nanodiamond clusters

    Science.gov (United States)

    Vanyukov, V. V.; Mikheev, G. M.; Mogileva, T. N.; Puzyr, A. P.; Bondar, V. S.; Svirko, Y. P.

    2014-11-01

    Optical limiting (OL) is observed for detonation nanodiamond clusters (ND) suspended in water with mass concentrations of 3-0.01%. By using nanosecond Z-scan measurements at 1064 nm we demonstrate that the nonlinear light scattering strongly contributes to the OL in a wide range of ND concentrations. Moreover we show that the ratio of the nonlinear and linear extinction that can be seen as figure of merit for an optical limiter is a non-monotonous function of the ND concentration. Our analysis reveals that the concentration that corresponds to the optimum OL performance essentially depends on the incident intensity.

  12. Limits on spin-dependent WIMP-nucleon cross sections from the XENON10 experiment.

    Science.gov (United States)

    Angle, J; Aprile, E; Arneodo, F; Baudis, L; Bernstein, A; Bolozdynya, A; Coelho, L C C; Dahl, C E; DeViveiros, L; Ferella, A D; Fernandes, L M P; Fiorucci, S; Gaitskell, R J; Giboni, K L; Gomez, R; Hasty, R; Kastens, L; Kwong, J; Lopes, J A M; Madden, N; Manalaysay, A; Manzur, A; McKinsey, D N; Monzani, M E; Ni, K; Oberlack, U; Orboeck, J; Plante, G; Santorelli, R; dos Santos, J M F; Shagin, P; Shutt, T; Sorensen, P; Schulte, S; Winant, C; Yamashita, M

    2008-08-29

    XENON10 is an experiment to directly detect weakly interacting massive particles (WIMPs), which may comprise the bulk of the nonbaryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with 129Xe and 131Xe from 58.6 live days of operation at the Laboratori Nazionali del Gran Sasso. Based on the nonobservation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of approximately 10 GeV/c2-2 TeV/c2 as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

  13. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit

    Science.gov (United States)

    Huang, Bevin; Clark, Genevieve; Navarro-Moratalla, Efrén; Klein, Dahlia R.; Cheng, Ran; Seyler, Kyle L.; Zhong, Ding; Schmidgall, Emma; McGuire, Michael A.; Cobden, David H.; Yao, Wang; Xiao, Di; Jarillo-Herrero, Pablo; Xu, Xiaodong

    2017-06-01

    Since the discovery of graphene, the family of two-dimensional materials has grown, displaying a broad range of electronic properties. Recent additions include semiconductors with spin-valley coupling, Ising superconductors that can be tuned into a quantum metal, possible Mott insulators with tunable charge-density waves, and topological semimetals with edge transport. However, no two-dimensional crystal with intrinsic magnetism has yet been discovered; such a crystal would be useful in many technologies from sensing to data storage. Theoretically, magnetic order is prohibited in the two-dimensional isotropic Heisenberg model at finite temperatures by the Mermin-Wagner theorem. Magnetic anisotropy removes this restriction, however, and enables, for instance, the occurrence of two-dimensional Ising ferromagnetism. Here we use magneto-optical Kerr effect microscopy to demonstrate that monolayer chromium triiodide (CrI3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 kelvin is only slightly lower than that of the bulk crystal, 61 kelvin, which is consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phase, highlighting thickness-dependent physical properties typical of van der Waals crystals. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect, whereas in trilayer CrI3 the interlayer ferromagnetism observed in the bulk crystal is restored. This work creates opportunities for studying magnetism by harnessing the unusual features of atomically thin materials, such as electrical control for realizing magnetoelectronics, and van der Waals engineering to produce interface phenomena.

  14. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit.

    Science.gov (United States)

    Huang, Bevin; Clark, Genevieve; Navarro-Moratalla, Efrén; Klein, Dahlia R; Cheng, Ran; Seyler, Kyle L; Zhong, Ding; Schmidgall, Emma; McGuire, Michael A; Cobden, David H; Yao, Wang; Xiao, Di; Jarillo-Herrero, Pablo; Xu, Xiaodong

    2017-06-07

    Since the discovery of graphene, the family of two-dimensional materials has grown, displaying a broad range of electronic properties. Recent additions include semiconductors with spin-valley coupling, Ising superconductors that can be tuned into a quantum metal, possible Mott insulators with tunable charge-density waves, and topological semimetals with edge transport. However, no two-dimensional crystal with intrinsic magnetism has yet been discovered; such a crystal would be useful in many technologies from sensing to data storage. Theoretically, magnetic order is prohibited in the two-dimensional isotropic Heisenberg model at finite temperatures by the Mermin-Wagner theorem. Magnetic anisotropy removes this restriction, however, and enables, for instance, the occurrence of two-dimensional Ising ferromagnetism. Here we use magneto-optical Kerr effect microscopy to demonstrate that monolayer chromium triiodide (CrI3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 kelvin is only slightly lower than that of the bulk crystal, 61 kelvin, which is consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phase, highlighting thickness-dependent physical properties typical of van der Waals crystals. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect, whereas in trilayer CrI3 the interlayer ferromagnetism observed in the bulk crystal is restored. This work creates opportunities for studying magnetism by harnessing the unusual features of atomically thin materials, such as electrical control for realizing magnetoelectronics, and van der Waals engineering to produce interface phenomena.

  15. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    DEFF Research Database (Denmark)

    Scholz, Florian; Löscher, Carolin; Fiskal, Annika

    2016-01-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface....... Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling...... campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations>300 nM. At the boundary between...

  16. Impact of thermal dependence of elastic constants on surface stress measurements

    Science.gov (United States)

    Kury, Peter; Horn-von Hoegen, Michael

    2004-05-01

    The accuracy of surface stress data obtained by means of bending sample methods depends on the precise knowledge of the biaxial Youngs modulus E/1-ν which enters as a prefactor in the stress calculation formula of Stoney and describes the stiffness of the sample's material against biaxial deformation. Room temperature values are commonly used for E/1-ν. However, E/1-ν is significantly temperature dependent. A second order polynomial fit of this dependence is presented for the benefit of future measurements as well as a correction curve for old data.

  17. Thermo-elastic plane deformations in doubly-connected domains with temperature and pressure which depend of the thermal conductivity

    Directory of Open Access Journals (Sweden)

    Giovanni Cimatti

    2014-05-01

    Full Text Available We propose a new weak formulation for the plane problem of thermoelastic theory in multiply-connected domains. This permits to avoid the difficulties connected with the Cesaro-Volterra boundary conditions in the related elliptic boundary-value problem. In the second part we consider a nonlinear version of the problem assuming that the thermal conductivity depends not only on the temperature but also on the pressure. Recent studies reveals that this situation can occur in practice. A theorem of existence and uniqueness is proved for this problem.

  18. Temperature-dependent dielectric properties of liver tissue measured during thermal ablation: toward an improved numerical model.

    Science.gov (United States)

    Brace, Christopher L

    2008-01-01

    The development of microwave tumor ablation devices depends largely on numerical simulations of antenna characteristics and transient electromagnetic heating. However, without an adequate tissue model simulation predictions can vary widely from experimental results. In this study, tissue dielectric properties are measured to capture changes induced by temperature, cellular makeup and water content during thermal ablation. Measurements made using this technique agree closely with previous measurements for temperatures up to 50 degrees C, but both relative permittivity and conductivity decrease by as much as 50 percent when temperatures approach 100 degrees C.

  19. Analysis of shell-type structures subjected to time-dependent mechanical and thermal loading

    Science.gov (United States)

    Simitses, G. J.

    1989-01-01

    The objective is to develop a general mathematical model and solution methodologies for analyzing structural response of thin, metallic shell-type structures under large transient, cyclic, or static thermomechanical loads. Among the system responses, which are associated with these load conditions, are thermal buckling, creep buckling, and racheting. Thus, geometric as well as material-type nonlinearities (of high order) can be anticipated and must be considered in the development of the mathematical model. Furthermore, this must also be accommodated in the solution procedures.

  20. The metabolic, locomotor and sex-dependent effects of elevated temperature on Trinidadian guppies: limited capacity for acclimation.

    Science.gov (United States)

    Muñoz, Nicolas J; Breckels, Ross D; Neff, Bryan D

    2012-10-01

    Global warming poses a threat to many ectothermic organisms because of the harmful effects that elevated temperatures can have on resting metabolic rate (RMR) and body size. This study evaluated the thermal sensitivity of Trinidadian guppies (Poecilia reticulata) by describing the effects of developmental temperature on mass, burst speed and RMR, and investigated whether these tropical fish can developmentally acclimate to their thermal conditions. These traits were measured following exposure to one of three treatments: 70 days at 23, 25, 28 or 30°C (acclimated groups); 6 h at 23, 28 or 30°C following 70 days at 25°C (unacclimated groups); or 6 h at 25°C following 70 days in another 25°C tank (control group). Body mass was lower in warmer temperatures, particularly amongst females and individuals reared at 30°C. The burst speed of fish acclimated to each temperature did not differ and was marginally higher than that of unacclimated fish, indicative of complete compensation. Conversely, acclimated and unacclimated fish did not differ in their RMR at each temperature. Amongst the acclimated groups, RMR was significantly higher at 30°C, indicating that guppies may become thermally limited at this temperature as a result of less energy being available for growth, reproduction and locomotion. Like other tropical ectotherms, guppies appear to be unable to adjust their RMR through physiological acclimation and may consequently be susceptible to rising temperatures. Also, because larger females have higher fecundity, our data suggest that fecundity will be reduced in a warmer climate, potentially decreasing the viability of guppy populations.

  1. Fracture evaluation of thermally sprayed coatings in dependence on cohesive strength

    Science.gov (United States)

    Schubert, J.; Česánek, Z.

    2017-05-01

    Measuring the cohesive strength of thermally sprayed coatings is relatively difficult matter, which can be accessed in many directions. This issue is nowadays solved by use of Scratch test method. This method is not completely sufficient for the cohesive strength testing because the coating is under load of combined stresses during the Scratch test. The reason to develop this method was need for exact measurement of tensile cohesion toughness of thermally sprayed coatings, which could provide results as close to a classic tensile test as possible. Another reason for development of this method was the impossibility of direct comparison with results obtained by other methods. Tested coatings were prepared using HP / HVOF (Stellite 6, NiCrBSi, CrC-NiCr and Hastelloy C-276). These coatings were selected as commonly used in commercial sector and also on because of rising customer demand for ability to provide such coating characteristics. The tested coatings were evaluated in terms of cohesive strength (method based on tensile strength test). Final fractures were evaluated by optical microscopy together with scanning electron microscopy and EDS analysis. As expected higher cohesive strength showed metallic coatings with top results of coating Stellite 6. Carbide coatings showed approximately third of the cohesion strength in comparison with metal based coating.

  2. Damping Dependence of Reversal Magnetic Field on Co-based Nano-Ferromagnetic with Thermal Activation

    Directory of Open Access Journals (Sweden)

    Nadia Ananda Herianto

    2015-02-01

    Full Text Available Currently, hard disk development has used HAMR technology that applies heat to perpendicular media until near Curie temperature, then cools it down to room temperature. The use of HAMR technology is significantly influence by Gilbert damping constants. Damping affects the magnetization reversal and coercivity field. Simulation is used to evaluate magnetization reversal by completing Landau-Lifshitz-Gilbert explicit equation. A strong ferromagnetic cobalt based material with size 50×50×20 nm3 is used which parameters are anisotropy materials 3.51×106 erg/cm3, magnetic saturation 5697.5 G, exchange constant 1×10-7 erg/cm, and various Gilbert damping from 0.09 to 0.5. To observe the thermal effect, two schemes are used which are Reduced Barrier Writing and Curie Point Writing. As a result, materials with high damping is able to reverse the magnetizations faster and reduce the energy barrier. Moreover, it can lower the minimum field to start the magnetizations reversal, threshold field, and probability rate. The heating near Curie temperature has succeeded in reducing the reversal field to 1/10 compared to writing process in absence of thermal field.

  3. Dependence of electrical properties on thermal temperature in nanocrystalline SnO2 thin films.

    Science.gov (United States)

    Du, Juan; Zhang, HaiJiao; Jiao, Zheng; Wu, Minghong; Shek, Chan-Hung; Wu, C M Lawrence; Lai, Joseph K L; Chen, Zhiwen

    2011-12-01

    Nanocrystalline SnO2 thin films were prepared by pulsed laser deposition techniques on clean glass substrates, and the films were then annealed for 30 min from 50 to 550 degrees C with a step of 50 degrees C, respectively. The investigation of X-ray diffraction confirmed that the various SnO2 thin films were consisted of nanoparticles with average grain size in the range of 23.7-28.9 nm. Root-mean-square surface roughness of the as-prepared SnO2 thin film was measured to be 25.6 nm which decreases to 16.2 nm with thermal annealing. Electrical resistivity and refractive index were measured as a function of annealing temperature, and found to lie between 1.24 to 1.45 momega-cm, and 1.502 to 1.349, respectively. The results indicate that nearly opposite actions to root-mean-square surface roughness and electrical resistivity make a unique performance with thermal annealing temperature. The post annealing shows greater tendency to affect the structural and electrical properties of SnO2 thin films which composed of nanoparticles.

  4. Thermal Response and Stability Characteristics of Bistable Composite Laminates by Considering Temperature Dependent Material Properties and Resin Layers

    Science.gov (United States)

    Moore, M.; Ziaei-Rad, S.; Salehi, H.

    2013-02-01

    In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C and -60°C to 40°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained. Finally, the stability characteristics of a tapered composite panel were investigated for using in a sample winglet as a candidate application of bistable structures.

  5. Effects of Shear Dependent Viscosity and Variable Thermal Conductivity on the Flow and Heat Transfer in a Slurry

    Directory of Open Access Journals (Sweden)

    Ling Miao

    2015-10-01

    Full Text Available In this paper we study the effects of variable viscosity and thermal conductivity on the heat transfer in the pressure-driven fully developed flow of a slurry (suspension between two horizontal flat plates. The fluid is assumed to be described by a constitutive relation for a generalized second grade fluid where the shear viscosity is a function of the shear rate, temperature and concentration. The heat flux vector for the slurry is assumed to follow a generalized form of the Fourier’s equation where the thermal conductivity k depends on the temperature as well as the shear rate. We numerically solve the governing equations of motion in the non-dimensional form and perform a parametric study to see the effects of various dimensionless numbers on the velocity, volume fraction and temperature profiles. The different cases of shear thinning and thickening, and the effect of the exponent in the Reynolds viscosity model, for the temperature variation in viscosity, are also considered. The results indicate that the variable thermal conductivity can play an important role in controlling the temperature variation in the flow.

  6. Pushing the limits. Chronotype- and time-of-day modulate working memory-dependent cerebral activity

    Directory of Open Access Journals (Sweden)

    Christina eSchmidt#

    2015-09-01

    Full Text Available Morning type individuals experience more difficulties to maintain optimal attentional performance throughout a normal waking day than evening types. However, time-of-day modulations may differ across cognitive domains. Using functional magnetic resonance imaging (fMRI, we investigated how chronotype and time of day interact with working memory at different levels of cognitive load/complexity in a N-back paradigm (N0-, N2- and N3-back levels. Extreme morning and evening type individuals underwent 2 fMRI sessions during N-back performance, one 1.5 h (morning and one 10.5 h (evening after wake-up time scheduled according to their habitual sleep-wake preference. At the behavioural level, increasing working memory load resulted in lower accuracy, while chronotype and time of day only exerted a marginal impact on performance. Analyses of neuroimaging data disclosed an interaction between chronotype, time of day and the modulation of cerebral activity by working memory load in the thalamus and in the middle frontal cortex. In the subjective evening hours, evening types exhibited higher thalamic activity than morning types at the highest working memory load condition only (N3-back. Conversely, morning type individuals exhibited higher activity than evening type participants in the middle frontal gyrus during the morning session in the N3-back condition. Our data emphasize inter-individual differences in time-of-day preferences and underlying cerebral activity, which should be taken into account when investigating vigilance state effects in task-related brain activity. These results support the hypothesis that higher task complexity leads to a chronotype-dependent increase in thalamic and frontal brain activity, permitting stabilization of working memory performance across the day.

  7. Pushing the Limits: Chronotype and Time of Day Modulate Working Memory-Dependent Cerebral Activity.

    Science.gov (United States)

    Schmidt, Christina; Collette, Fabienne; Reichert, Carolin F; Maire, Micheline; Vandewalle, Gilles; Peigneux, Philippe; Cajochen, Christian

    2015-01-01

    Morning-type individuals experience more difficulties to maintain optimal attentional performance throughout a normal waking day than evening types. However, time-of-day modulations may differ across cognitive domains. Using functional magnetic resonance imaging (fMRI), we investigated how chronotype and time of day interact with working memory at different levels of cognitive load/complexity in a N-back paradigm (N0-, N2-, and N3-back levels). Extreme morning- and evening-type individuals underwent two fMRI sessions during N-back performance, one 1.5 h (morning) and one 10.5 h (evening) after wake-up time scheduled according to their habitual sleep-wake preference. At the behavioral level, increasing working memory load resulted in lower accuracy while chronotype and time of day only exerted a marginal impact on performance. Analyses of neuroimaging data disclosed an interaction between chronotype, time of day, and the modulation of cerebral activity by working memory load in the thalamus and in the middle frontal cortex. In the subjective evening hours, evening types exhibited higher thalamic activity than morning types at the highest working memory load condition only (N3-back). Conversely, morning-type individuals exhibited higher activity than evening-type participants in the middle frontal gyrus during the morning session in the N3-back condition. Our data emphasize interindividual differences in time-of-day preferences and underlying cerebral activity, which should be taken into account when investigating vigilance state effects in task-related brain activity. These results support the hypothesis that higher task complexity leads to a chronotype-dependent increase in thalamic and frontal brain activity, permitting stabilization of working memory performance across the day.

  8. Tryptophan Codon-Dependent Transcription in Chlamydia pneumoniae during Gamma Interferon-Mediated Tryptophan Limitation.

    Science.gov (United States)

    Ouellette, Scot P; Rueden, Kelsey J; Rucks, Elizabeth A

    2016-09-01

    In evolving to an obligate intracellular niche, Chlamydia has streamlined its genome by eliminating superfluous genes as it relies on the host cell for a variety of nutritional needs like amino acids. However, Chlamydia can experience amino acid starvation when the human host cell in which the bacteria reside is exposed to interferon gamma (IFN-γ), which leads to a tryptophan (Trp)-limiting environment via induction of the enzyme indoleamine-2,3-dioxygenase (IDO). The stringent response is used to respond to amino acid starvation in most bacteria but is missing from Chlamydia Thus, how Chlamydia, a Trp auxotroph, responds to Trp starvation in the absence of a stringent response is an intriguing question. We previously observed that C. pneumoniae responds to this stress by globally increasing transcription while globally decreasing translation, an unusual response. Here, we sought to understand this and hypothesized that the Trp codon content of a given gene would determine its transcription level. We quantified transcripts from C. pneumoniae genes that were either rich or poor in Trp codons and found that Trp codon-rich transcripts were increased, whereas those that lacked Trp codons were unchanged or even decreased. There were exceptions, and these involved operons or large genes with multiple Trp codons: downstream transcripts were less abundant after Trp codon-rich sequences. These data suggest that ribosome stalling on Trp codons causes a negative polar effect on downstream sequences. Finally, reassessing previous C. pneumoniae microarray data based on codon content, we found that upregulated transcripts were enriched in Trp codons, thus supporting our hypothesis. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. pH- and thermal-dependent conformational transition of PGAIPG, a repeated hexapeptide sequence from tropoelastin.

    Science.gov (United States)

    Lin, Shan-Yang; Hsieh, Tzu-Feng; Wei, Yen-Shan

    2005-04-01

    The secondary structure of PGAIPG (Pro-Gly-Ala-IIe-Pro-Gly), a repeated hexapeptide of tropoelastin, in buffer solution of different pH was determined by using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The thermal-dependent structural change of PGAIPG in aqueous solution or in solid state was also examined by thermal FTIR microspectroscopy. The conformation of PGAIPG in aqueous solution exhibited a pH-dependent structural characterization. A predominant peak at 1614 cm(-1) (aggregated beta-sheet) with a shoulder near 1560 cm(-1) (beta-sheet) appeared in pH 5.5-8.5 buffer solutions. A new broad shoulder at 1651 cm(-1) (random coil and/or alpha-helix) with 1614 cm(-1) was observed in the pH 4.5 buffer solution. However, the broad shoulder at 1651 cm(-1) was converted to a maximum peak at 1679 cm(-1) (beta-turn/antiparallel beta-sheet) when the pH shifted from 4.5 to 3.5, but the original pronounced peak at 1614 cm(-1) became a shoulder. Once the pH was lowered to 2.5, the IR spectrum of PGAIPG was dominated by major absorption at 1679 cm(-1) with a minor peak at 1552 cm(-1) (alpha-helix/random coil). The result indicates that the pH was a predominant factor to transform PGAIPG structure from aggregated beta-sheet (pH 8.5) to beta-turn/intermolecular antiparallel beta-sheet (pH 2.5). Moreover, a partial conformation of PGAIPG with minor alpha-helix/random coil structures was also explored in the lower pH buffer solution. There was no thermal-dependent structural change for solid-state PGAIPG. The thermal-induced formation of aggregated beta-sheet for PGAIPG in aqueous solution was found from 28 to 30 degrees C, however, which might be correlated with the formation of an opaque gel that turned from clear solution. The formation of aggregated beta-sheet structure for PGAIPG beyond 30 degrees C might be due to the intermolecular hydrogen bonded interaction between the hydrophobic PGAIPG fragments induced by coacervation.

  10. Dependence of Hardness of Silicate Glasses on Composition and Thermal History

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Yue, Yuanzheng

    The prediction of hardness is possible for crystalline materials, but so far not possible for glasses. In this work, several important factors that should be used for predicting the hardness of glasses are discussed. To do so, we have studied the influences of thermal history and chemical...... composition on hardness of silicate glasses. E-glasses of different compositions are subjected to various degrees of annealing to obtain various fictive temperatures in the glasses. It is found that hardness decreases with the fictive temperature. Addition of Na2O to a SiO2-Al2O3-Na2O glass system causes...... a decrease in hardness. However, hardness cannot solely be determined from the degree of polymerisation of the glass network. It is also determined by the effect of ionic radius on hardness. However, this effect has opposite trend for alkali and alkaline earth ions. The hardness increases with ionic radius...

  11. Performance analysis of pin fins with temperature dependent thermal parameters using the variation of parameters method

    Directory of Open Access Journals (Sweden)

    Cihat Arslantürk

    2016-08-01

    Full Text Available The performance of pin fins transferring heat by convection and radiation and having variable thermal conductivity, variable emissivity and variable heat transfer coefficient was investigated in the present paper. Nondimensionalizing the fin equation, the problem parameters which affect the fin performance were obtained. Dimensionless nonlinear fin equation was solved with the variation of parameters method, which is quite new in the solution of nonlinear heat transfer problems. The solution of variation of parameters method was compared with known analytical solutions and some numerical solution. The comparisons showed that the solutions are seen to be perfectly compatible. The effects of problem parameters were investigated on the heat transfer rate and fin efficiency and results were presented graphically.

  12. Nonlocal microstructure-dependent dynamic stability of refined porous FG nanoplates in hygro-thermal environments

    Science.gov (United States)

    Reza Barati, Mohammad

    2017-10-01

    Based on the generalized nonlocal strain gradient theory (NSGT), dynamic modeling and analysis of nanoporous inhomogeneous nanoplates is presented. Therefore, it is possible to capture both stiffness-softening and stiffness-hardening effects for a more accurate dynamic analysis of nanoplates. The nanoplate is in hygro-thermal environments and is subjected to an in-plane harmonic load. Porosities are incorporated to the model based on a modified rule of mixture. Modeling of the porous nanoplate is conducted according to a refined four-variable plate theory with fewer field variables than in the first-order plate theory. The governing equations and related classical and nonclassical boundary conditions are derived based on Hamilton's principle. These equations are solved for hinged nanoplates via Galerkin's method. It is shown that porosities, moisture rise, temperature rise, nonlocal parameter, strain gradient parameter, material gradation, elastic foundation and uniform dynamic load have a remarkable influence on the dynamic behavior of nanoscale plates.

  13. Growth form-dependent response to physical disturbance and thermal stress in Acropora corals

    Science.gov (United States)

    Muko, S.; Arakaki, S.; Nagao, M.; Sakai, Kazuhiko

    2013-03-01

    To predict the community structure in response to changing environmental conditions, it is necessary to know the species-specific reaction and relative impact strength of each disturbance. We investigated the coral communities in two sites, an exposed and a protected site, at Iriomote Island, Japan, from 2005 to 2008. During the study period, a cyclone and thermal stress were observed. All Acropora colonies, classified into four morphologies (arborescent, tabular, corymbose, and digitate), were identified and tracked through time to calculate the annual mortality and growth rate. The mortality of all Acropora colonies in the protected site was lower than that in the exposed site during the period without disturbances. Extremely higher mortality due to bleaching was observed in tabular and corymbose Acropora, compared to other growth forms, at the protected sites after thermal stress. In contrast, physical disturbance by a tropical cyclone induced the highest mortality in arborescent and digitate corals at the exposed site. Moreover, arborescent corals exhibited a remarkable decline 1 year after the tropical cyclone at the exposed site. The growth of colonies that survived coral bleaching did not decrease in the following year compared to previous year for all growth forms, but the growth of arborescent and tabular remnant corals at the exposed site declined severely after the tropical cyclone compared to previous year. The delayed mortality and lowered growth rate after the tropical cyclone were probably due to the damage caused by the tropical cyclone. These results indicate that the cyclone had a greater impact on fragile corals than expected. This study provides useful information for the evaluation of Acropora coral response to progressing global warming conditions, which are predicted to increase in frequency and intensity in the near future.

  14. Effect of Erbium substitution on temperature and field dependence of thermally activated flux flow resistance in Bi-2212 superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Paladhi, D.; Mandal, P.; Sahoo, R.C.; Giri, S.K.; Nath, T.K., E-mail: tnath@phy.iitkgp.ernet.in

    2016-12-01

    Thermally activated flux flow (TAFF) regime of Er doped Bi{sub 2}Sr{sub 2}Ca{sub 1−x}Er{sub x}Cu{sub 2}O{sub 8+δ} (x=0.0, 0.1, 0.3) polycrystalline systems have been investigated using magneto-transport measurements up to 70 kOe magnetic field. High quality single phase samples have been prepared by standard solid state reaction method. The activation energy or pinning strength (U{sub 0}) have been calculated using thermally activated flux flow (TAFF) model by linear fitting from the semi-logarithmic curve of ln ρ vs 1/T. It has been observed that activation energy (U{sub 0}) decreases with Er substitution and U{sub 0} follows power law dependence with magnetic field for all three samples. Irreversibility lines (IL) have been drawn from the magneto-transport data for all three samples and it is observed that IL shifts to lower temperature with higher Er concentration. It is confirmed from the above results that pinning strength becomes weaker with Er doping. Finally, the variation of U{sub 0} have been shown with temperature by re-plotting –T(ln (ρ/ρ{sub 100})) vs T for three samples showing non-linear dependence with temperature.

  15. Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization

    DEFF Research Database (Denmark)

    Cardoso, J. F.; Delabrouille, J.; Ganga, K.

    2015-01-01

    Planck has mapped the intensity and polarization of the sky at microwave frequencies with unprecedented sensitivity. We use these data to characterize the frequency dependence of dust emission. We make use of the Planck 353 GHz I, Q, and U Stokes maps as dust templates, and cross-correlate them w...

  16. Comparison of thermal runaway limits under different test conditions based on a 4.5 kV IGBT

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Prindle, D.; Pâques, Gontran

    2016-01-01

    runaway takes place. In this paper guidelines are proposed based on the correlation among short circuit withstand capability and off-state leakage current for guarantying reliable operation and ensuring that they are thermally stable under parameter variations. This study is helpful to facilitate...... application engineers for defining the correct stability criteria and/or margins in respect of thermal runaway....... at high temperatures is given by comparing the different testing methods: Static performance (including and excluding self-heating effects), Short Circuit Safe Operating area and High-Temperature Reverse Bias. Additionally, a thermal model is used to predict the junction temperature at which thermal...

  17. Adomian Decomposition Method for a Nonlinear Heat Equation with Temperature Dependent Thermal Properties

    Directory of Open Access Journals (Sweden)

    Ashfaque H. Bokhari

    2009-01-01

    Full Text Available The solutions of nonlinear heat equation with temperature dependent diffusivity are investigated using the modified Adomian decomposition method. Analysis of the method and examples are given to show that the Adomian series solution gives an excellent approximation to the exact solution. This accuracy can be increased by increasing the number of terms in the series expansion. The Adomian solutions are presented in some situations of interest.

  18. The Temperature Condition of the Plate with Temperature-Dependent Thermal Conductivity and Energy Release

    OpenAIRE

    V. S. Zarubin; A. V. Kotovich; G. N. Kuvyrkin

    2016-01-01

    The temperature state of a solid body, in addition to the conditions of its heat exchange with the environment, can greatly depend on the heat release (or heat absorption) processes within the body volume. Among the possible causes of these processes should be noted such as a power release in the fuel elements of nuclear reactors, exothermic or endothermic chemical reactions in the solid body material, which respectively involve heat release or absorbtion, heat transfer of a part of the elect...

  19. Modeling of Circuits with Strongly Temperature Dependent Thermal Conductivities for Cryogenic CMOS

    OpenAIRE

    Hamlet, J.; Eng, K.; Gurrieri, T.; Levy, J; Carroll, M

    2010-01-01

    When designing and studying circuits operating at cryogenic temperatures understanding local heating within the circuits is critical due to the temperature dependence of transistor and noise behavior. We have investigated local heating effects of a CMOS ring oscillator and current comparator at T=4.2K. In two cases, the temperature near the circuit was measured with an integrated thermometer. A lumped element equivalent electrical circuit SPICE model that accounts for the strongly temperature...

  20. The pH-dependent thermal and storage stability of glycosylated caseinomacropeptide

    DEFF Research Database (Denmark)

    Siegert, Nadja; Tolkach, Alexander; Kulozik, Ulrich

    2012-01-01

    manufacturing gCMP can be modified due to processing. Processing conditions, which influence the degree of glycosylation of gCMP lead to alterations of bioactivity and techno-functional properties of gCMP and accordingly gCMP-containing products. Hence, gCMP was studied for its glycan stability during heat...... treatment and storage under different pH values. Process stability (preservation of native protein structure in terms of attached glycans) was analysed by quantifying the release of the terminal carbohydrate, N-acetylneuraminic acid (Neu5Ac), from gCMP. The results clearly showed that the thermal stability...... of gCMP is strongly influenced by pH. When the pH was decreased from 7 to 2, reduced stability was found even at low heating temperatures. Minimal destabilisation effects were found at neutral pH. Similar observations were found during storage of gCMP. Neu5Ac was released after six days of storage...

  1. Theoretical study of the pressure dependent rate constants of the thermal decomposition of β-propiolactone

    Directory of Open Access Journals (Sweden)

    Abolfazl Shiroudi

    2015-09-01

    Full Text Available A theoretical study of the thermal decomposition of β-propiolactone is carried out using ab initio molecular orbital (MO methods at the MP2/6-311+G∗∗ level and Rice–Ramsperger–Kassel–Marcus (RRKM theory. The reported experimental results showed that decomposition of β-propiolactone occurred by three competing homogeneous and first order reactions. For the three reactions, the calculation was also performed at the MP2/6-311+G∗∗ level of theory, as well as by single-point calculations at the B3LYP/6-311+G∗∗//MP2/6-311+G∗∗, and MP4/6-311+G∗∗//MP2/6-311+G∗∗ levels of theory. The fall-off pressures for the decomposition in these reactions are found to be 2.415, 9.423 × 10−2 and 3.676 × 10−3 mmHg, respectively.

  2. Compositional dependence of thermal, optical and mechanical properties of oxyfluoride glass

    Science.gov (United States)

    Hager, I. Z.; Othman, H. A.; Valiev, D. T.

    2017-05-01

    Tungsten oxyfluoride glasses are characterized by low phonon energy. This is due to the presence of fluoride ions that have low phonon energy and formation of low phonon energy WO6 units. Oxyfluoride glasses based on WO3-BaF2-RF, where RF = LiF, NaF or mixed (LiF-NaF) have been prepared by melt quenching technique. The density and molar volume of the prepared glasses show a decrease with the increase of RF instead of WO3 content. The glass transition temperature Tg is found to decrease with increasing RF content. The refractive index increases with the addition of heavy polarizable fluorides. The decrease of the elastic moduli and microhardness of these glasses may be due to the decrease in density and the depolymrization effect. The Poisson’s ratio increases with increasing RF content due to the structural changes and formation of (NBOs) and (NBF) units. The aim of this work is to prepare a glass host with low phonon energy to be an efficient host with good luminescence properties, when doped with rare earth ions, and to study its structural, thermal, optical and mechanical properties.

  3. Foam nests provide context-dependent thermal insulation to embryos of three leptodactylid frogs.

    Science.gov (United States)

    Méndez-Narváez, J; Flechas, S V; Amézquita, A

    2015-01-01

    The choice of adequate breeding habitat and its associated thermoregulatory conditions are thought to be important in the evolution of amphibian reproductive strategies. Among leptodactylid frogs, there is a terrestrial cline in the oviposition sites chosen to build foam nests for eggs. Although several functions have been attributed to foam nests, their role in temperature regulation for embryos is unclear. Here we tested the hypothesis that foam nests buffer embryos from variation in air temperature. We examined the degree of terrestrial nest sites in three species, finding a terrestrial cline of sites in terms of distance from water. We tested whether this nest-insulation effect varied among these species that differ in the degree of terrestrial nest sites and whether translocating nests impacted embryonic mortality. Our results demonstrate a negative effect of translocating aquatic nests to land, inferred from the highest hatching success in natural nests sites. All nests attenuated environmental thermal variation, but more terrestrial nests buffered embryos from a greater range of temperatures than did aquatic ones. Altogether, our data indicate that foam nests insulate embryos from daily temperature fluctuations among leptodactylid frogs with different degrees of terrestrial nests, which may well have contributed to the evolution of this reproductive strategy.

  4. Magnetic Susceptibility depending on the Thermal Degradation of HK-40 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Min; Park, Jong Seo; Nahm, Seung Hoon [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Son, De Rac [Hannam University, Daejeon (Korea, Republic of); Kim, Dong Gyun [Kyungpook National University, Daegu (Korea, Republic of); Han, Sang In; Choi, Song Chun [Korea Gas Safety Corporation, Siheung (Korea, Republic of); Ryu, Dae Hyun [Hansei University, Gunpo (Korea, Republic of)

    2004-02-15

    Since the used materials of furnace heater tube with different kinds of thermal degradation were not commonly available, the HK-40 steel specimens were heat-treated isothermally at elevated temperature to simulate the microstructure at the service temperature. HK-40 steel specimens with five different aging time were prepared by isothermal heat treatment at 1050 .deg. C . The characteristics of the magnetic susceptibility have been investigated for the degradation evaluation of HK-40 steel. The magnetic susceptibility at room temperature increases as the extent of degradation of the materials increases. The variation of magnetic susceptibility was compared with the variation of tensile properties and Vickers hardness. To investigate the effect of the microsturctural change on the characteristics of tensile properties, hardness and magnetic susceptibility, the microstructures were examined by a scanning electron microscope(SEM) and the chemical compositions were analyzed by a energy spectrometer of SEM. As a result, the magnetic susceptibility method can be suggested as one of the nondestructive evaluation methods for the degradation of the HK-40 steel

  5. Novel Resistance Measurement Method: Analysis of Accuracy and Thermal Dependence with Applications in Fiber Materials

    Directory of Open Access Journals (Sweden)

    Silvia Casans

    2016-12-01

    Full Text Available Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources affecting the accuracy. Accuracy and extended uncertainty are obtained for a pattern decade box, showing a maximum of 1 % accuracy for temperatures below 30 ∘ C in the range from 1 MΩ to 100 GΩ. Thermal analysis showed stability up to 50 ∘ C for values below 10 GΩ and systematic deviations for higher values. Power supply V i applied to the measurement probes is also analysed, showing no differences in case of the pattern decade box, except for resistance values above 10 GΩ and temperatures above 35 ∘ C. To evaluate the circuit behaviour under fiber materials, an 11-day drying process in timber from four species (Oregon pine-Pseudotsuga menziesii, cedar-Cedrus atlantica, ash-Fraxinus excelsior, chestnut-Castanea sativa was monitored. Results show that the circuit, as expected, provides different resistance values (they need individual conversion curves for different species and the same ambient conditions. Additionally, it was found that, contrary to the decade box analysis, V i affects the resistance value due to material properties. In summary, the proposed circuit is able to accurately measure material resistance that can be further related to material properties.

  6. Novel Resistance Measurement Method: Analysis of Accuracy and Thermal Dependence with Applications in Fiber Materials.

    Science.gov (United States)

    Casans, Silvia; Rosado-Muñoz, Alfredo; Iakymchuk, Taras

    2016-12-14

    Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources affecting the accuracy. Accuracy and extended uncertainty are obtained for a pattern decade box, showing a maximum of 1 % accuracy for temperatures below 30 ∘ C in the range from 1 MΩ to 100 GΩ. Thermal analysis showed stability up to 50 ∘ C for values below 10 GΩ and systematic deviations for higher values. Power supply V i applied to the measurement probes is also analysed, showing no differences in case of the pattern decade box, except for resistance values above 10 GΩ and temperatures above 35 ∘ C. To evaluate the circuit behaviour under fiber materials, an 11-day drying process in timber from four species (Oregon pine-Pseudotsuga menziesii, cedar-Cedrus atlantica, ash-Fraxinus excelsior, chestnut-Castanea sativa) was monitored. Results show that the circuit, as expected, provides different resistance values (they need individual conversion curves) for different species and the same ambient conditions. Additionally, it was found that, contrary to the decade box analysis, V i affects the resistance value due to material properties. In summary, the proposed circuit is able to accurately measure material resistance that can be further related to material properties.

  7. Mass Dependency of Isotope Fractionation of Gases Under Thermal Gradient and Its Possible Implications for Planetary Atmosphere Escaping Process

    Science.gov (United States)

    Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard

    2014-01-01

    Physical processes that unmix elements/isotopes of gas molecules involve phase changes, diffusion (chemical or thermal), effusion and gravitational settling. Some of those play significant roles for the evolution of chemical and isotopic compositions of gases in planetary bodies which lead to better understanding of surface paleoclimatic conditions, e.g. gas bubbles in Antarctic ice, and planetary evolution, e.g. the solar-wind erosion induced gas escaping from exosphere on terrestrial planets.. A mass dependent relationship is always expected for the kinetic isotope fractionations during these simple physical processes, according to the kinetic theory of gases by Chapman, Enskog and others [3-5]. For O-bearing (O16, -O17, -O18) molecules the alpha O-17/ alpha O-18 is expected at 0.5 to 0.515, and for S-bearing (S32,-S33. -S34, -S36) molecules, the alpha S-33/ alpha S-34 is expected at 0.5 to 0.508, where alpha is the isotope fractionation factor associated with unmixing processes. Thus, one isotope pair is generally proxied to yield all the information for the physical history of the gases. However, we recently] reported the violation of mass law for isotope fractionation among isotope pairs of multiple isotope system during gas diffusion or convection under thermal gradient (Thermal Gradient Induced Non-Mass Dependent effect, TGI-NMD). The mechanism(s) that is responsible to such striking observation remains unanswered. In our past studies, we investigated polyatomic molecules, O2 and SF6, and we suggested that nuclear spin effect could be responsible to the observed NMD effect in a way of changing diffusion coefficients of certain molecules, owing to the fact of negligible delta S-36 anomaly for SF6.. On the other hand, our results also showed that for both diffusion and convection under thermal gradient, this NMD effect is increased by lower gas pressure, bigger temperature gradient and lower average temperature, which indicate that the nuclear spin effect may

  8. Inventory models with stock- and price-dependent demand for deteriorating items based on limited shelf space

    Directory of Open Access Journals (Sweden)

    Chang Chun-Tao

    2010-01-01

    Full Text Available This paper deals with the problem of determining the optimal selling price and order quantity simultaneously under EOQ model for deteriorating items. It is assumed that the demand rate depends not only on the on-display stock level but also the selling price per unit, as well as the amount of shelf/display space is limited. We formulate two types of mathematical models to manifest the extended EOQ models for maximizing profits and derive the algorithms to find the optimal solution. Numerical examples are presented to illustrate the models developed and sensitivity analysis is reported.

  9. Shutter-Less Temperature-Dependent Correction for Uncooled Thermal Camera Under Fast Changing FPA Temperature

    Science.gov (United States)

    Lin, D.; Westfeld, P.; Maas, H.-G.

    2017-05-01

    Conventional temperature-dependant correction methods for uncooled cameras are not so valid for images under the condition of fast changing FPA temperature as usual, therefore, a shutter-less temperature-dependant correction method is proposed here to compensate for these errors and stabilize camera's response only related to the object surface temperature. Firstly, sequential images are divided into the following three categories according to the changing speed of FPA temperature: stable (0°C/min), relatively stable (0.5°C/min). Then all of the images are projected into the same level using a second order polynomial relation between FPA temperatures and gray values from stable images. Next, a third order polynomial relation between temporal differences of FPA temperatures and the above corrected images is implemented to eliminate the deviation caused by fast changing FPA temperature. Finally, radiometric calibration is applied to convert image gray values into object temperature values. Experiment results show that our method is more effective for fast changing FPA temperature data than FLIR GEV.

  10. Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements - Part I: MODIS brightness temperatures in the thermal infrared

    Science.gov (United States)

    Fauchez, Thomas; Platnick, Steven; Meyer, Kerry; Cornet, Céline; Szczap, Frédéric; Várnai, Tamás

    2017-07-01

    This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR) brightness temperatures (BTs) at the top of the atmosphere (TOA) as a function of spatial resolution from 50 m to 10 km. A realistic 3-D cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloud-top and base altitudes at 10 and 12 km, respectively, consisting of aggregate column crystals of Deff = 20 µm), and 3-D thermal infrared radiative transfer (RT) is simulated with the 3DMCPOL code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i) the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB) and the (ii) horizontal radiative transport (HRT) leading to the independent pixel approximation error (IPAE). A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatial-resolution results (above ˜ 250 m) with averaged values of up to 5-7 K, while the IPAE mainly impacts the high-spatial-resolution results (below ˜ 250 m) with average values of up to 1-2 K. A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 m. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal infrared. For off-nadir observations, the average total effect is increased and the minimum is shifted to coarser spatial resolutions.

  11. Loss of the osteogenic differentiation potential during senescence is limited to bone progenitor cells and is dependent on p53.

    Science.gov (United States)

    Despars, Geneviève; Carbonneau, Cynthia L; Bardeau, Pascal; Coutu, Daniel L; Beauséjour, Christian M

    2013-01-01

    DNA damage can lead to the induction of cellular senescence. In particular, we showed that exposure to ionizing radiation (IR) leads to the senescence of bone marrow-derived multipotent stromal cells (MSC) and osteoblast-like stromal cells (OB-SC), a phenotype associated with bone loss. The mechanism by which IR leads to bone dysfunction is not fully understood. One possibility involves that DNA damage-induced senescence limits the regeneration of bone progenitor cells. Another possibility entails that bone dysfunction arises from the inability of accumulating senescent cells to fulfill their physiological function. Indeed, we show here that exposure to IR prevented the differentiation and mineralization functions of MSC, an effect we found was limited to this population as more differentiated OB-SC could still form mineralize nodules. This is in contrast to adipogenesis, which was inhibited in both IR-induced senescent MSC and 3T3-L1 pre-adipocytes. Furthermore, we demonstrate that IR-induced loss of osteogenic potential in MSC was p53-dependent, a phenotype that correlates with the inability to upregulate key osteogenic transcription factors. These results are the first to demonstrate that senescence impacts osteogenesis in a cell type dependent manner and suggest that the accumulation of senescent osteoblasts is unlikely to significantly contribute to bone dysfunction in a cell autonomous manner.

  12. Loss of the osteogenic differentiation potential during senescence is limited to bone progenitor cells and is dependent on p53.

    Directory of Open Access Journals (Sweden)

    Geneviève Despars

    Full Text Available DNA damage can lead to the induction of cellular senescence. In particular, we showed that exposure to ionizing radiation (IR leads to the senescence of bone marrow-derived multipotent stromal cells (MSC and osteoblast-like stromal cells (OB-SC, a phenotype associated with bone loss. The mechanism by which IR leads to bone dysfunction is not fully understood. One possibility involves that DNA damage-induced senescence limits the regeneration of bone progenitor cells. Another possibility entails that bone dysfunction arises from the inability of accumulating senescent cells to fulfill their physiological function. Indeed, we show here that exposure to IR prevented the differentiation and mineralization functions of MSC, an effect we found was limited to this population as more differentiated OB-SC could still form mineralize nodules. This is in contrast to adipogenesis, which was inhibited in both IR-induced senescent MSC and 3T3-L1 pre-adipocytes. Furthermore, we demonstrate that IR-induced loss of osteogenic potential in MSC was p53-dependent, a phenotype that correlates with the inability to upregulate key osteogenic transcription factors. These results are the first to demonstrate that senescence impacts osteogenesis in a cell type dependent manner and suggest that the accumulation of senescent osteoblasts is unlikely to significantly contribute to bone dysfunction in a cell autonomous manner.

  13. Monitoring thermally induced structural deformation and framework decomposition of ZIF-8 through in situ temperature dependent measurements.

    Science.gov (United States)

    Xu, Ben; Mei, Yingjie; Xiao, Zhenyu; Kang, Zixi; Wang, Rongming; Sun, Daofeng

    2017-10-18

    ZIF-8 is an easily synthesized porous material which is widely applied in gas storage/separation, catalysis, and nanoarchitecture fabrication. Thermally induced atomic displacements and the resultant framework deformation/collapse significantly influence the application of ZIF-8, and therefore, in situ temperature dependent FTIR spectroscopy was utilized to study the framework changes during heating in the oxidative environment. The results suggest that ZIF-8 undergoes three transition stages, which are the lattice expansion stage below 200 °C, the "reversible" structural deformation stage from 200 to 350 °C, and the decomposition/collapse stage over 350 °C. Our research indicates that the Zn-N bond breaks at a temperature of 350 °C in the oxidant environment, leading to a drastic deformation of the ZIF-8 structure.

  14. Time Dependent MHD Nano-Second Grade Fluid Flow Induced by Permeable Vertical Sheet with Mixed Convection and Thermal Radiation.

    Science.gov (United States)

    Ramzan, Muhammad; Bilal, Muhammad

    2015-01-01

    The aim of present paper is to study the series solution of time dependent MHD second grade incompressible nanofluid towards a stretching sheet. The effects of mixed convection and thermal radiation are also taken into account. Because of nanofluid model, effects Brownian motion and thermophoresis are encountered. The resulting nonlinear momentum, heat and concentration equations are simplified using appropriate transformations. Series solutions have been obtained for velocity, temperature and nanoparticle fraction profiles using Homotopy Analysis Method (HAM). Convergence of the acquired solution is discussed critically. Behavior of velocity, temperature and concentration profiles on the prominent parameters is depicted and argued graphically. It is observed that temperature and concentration profiles show similar behavior for thermophoresis parameter Νt but opposite tendency is noted in case of Brownian motion parameter Νb. It is further analyzed that suction parameter S and Hartman number Μ depict decreasing behavior on velocity profile.

  15. A thermal-capillary mechanism for a growth rate limit in edge-defined film-fed growth of silicon sheets

    Science.gov (United States)

    Thomas, P. D.; Ettouney, H. M.; Brown, R. A.

    1986-01-01

    Capillarity, acting to set the shape of the melt/gas interfaces, and heat transfer can interact to cause limits to steady-state growth of thin silicon sheets by the Edge-Defined Film-Fed Growth (EFG) method. A finite-element/Newton solution method for a two-dimensional thermal-capillary model of EFG is used to show that limiting values of pull rate exist beyond which steady-state growth is impossible. The pull rate limit is also predicted by a one-dimensional heat transfer model valid when the die sides and menisci are almost parallel and when the thermal conductivities of melt, crystal, and die are all equal. Both the one- and two-dimensional heat transfer models show that heat loss from the melt is dominated by conduction into the crystal and slow heat release to the ambient along the length of the ribbon. The limiting pull rate results from the reduced efficiency of conduction through the melt caused by the curvature of the meniscus which increases height of the die top above the level of the melt. Thermal-capillary limits are predicted for both positive and negative pressure differences across the meniscus.

  16. Thermal comfort

    CSIR Research Space (South Africa)

    Osburn, L

    2010-01-01

    Full Text Available wider range of temperature limits, saving energy while still satisfying the majority of building occupants. It is also noted that thermal comfort varies significantly between individuals and it is generally not possible to provide a thermal environment...

  17. Dependence of the thermal neutron fluence at the size installations radiotherapy bunker; Dependencia de la fluencia termica de neutrones en el tamano del bunquer en instalaciones de radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Soto, X.; Amgarou, K.; Langares, J. L.; Exposito, M. R.; Gomez, F.; Domingo, C.; Sanchez-Doblado, F.

    2011-07-01

    The project aims to infer the dose deposited by neutrons in the patient treated by radiation therapy, from a measurement of the thermal neutron fluence at a selected point within the treatment room. These thermal neutrons are created when fast neutrons produced in the linac head are moderate, mainly in the walls of the bunker, and its yield depends on both the volume of the room and its geometry.

  18. Hypoxic areas, density-dependence and food limitation drive the body condition of a heavily exploited marine fish predator

    DEFF Research Database (Denmark)

    Casini, Michele; Käll, Filip; Hansson, Martin

    2016-01-01

    Investigating the factors regulating fish condition is crucial in ecology and the management of exploited fish populations. The body condition of cod (Gadus morhua) in the Baltic Sea has dramatically decreased during the past two decades, with large implications for the fishery relying on this re......Investigating the factors regulating fish condition is crucial in ecology and the management of exploited fish populations. The body condition of cod (Gadus morhua) in the Baltic Sea has dramatically decreased during the past two decades, with large implications for the fishery relying...... shift that occurred in the Baltic Sea in the early 1990s. The changes in cod condition related to feeding opportunities, driven either by density-dependence or food limitation, along the whole period investigated and to the fivefold increase in the extent of hypoxic areas in the most recent 20 years...... and density-dependent processes. These results furnish novel insights into the population dynamics of Baltic Sea cod that can aid the management of this currently threatened population....

  19. Limited clinical efficacy of azacitidine in transfusion-dependent, growth factor-resistant, low- and Int-1-risk MDS

    DEFF Research Database (Denmark)

    Holm, Mette; Dybedahl, I; Holm, Mette

    2014-01-01

    This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks and a trans......This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks...... after Aza+Epo, giving a total response rate of 20%. Mutational screening revealed a high frequency of recurrent mutations. Although no single mutation predicted for response, SF3A1 (n=3) and DNMT3A (n=4) were only observed in non-responders. We conclude that Aza can induce TI in severely anemic MDS...... patients, but efficacy is limited, toxicity substantial and most responses of short duration. This treatment cannot be generally recommended in lower-risk MDS. Mutational screening revealed a high frequency of mutations....

  20. Site-Dependent Luminescence and Thermal Stability of Eu(2+) Doped Fluorophosphate toward White LEDs for Plant Growth.

    Science.gov (United States)

    Chen, Jiayu; Zhang, Niumiao; Guo, Chongfeng; Pan, Fengjuan; Zhou, Xianju; Suo, Hao; Zhao, Xiaoqi; Goldys, Ewa M

    2016-08-17

    Eu(2+) activated fluorophosphate Ba3GdNa(PO4)3F (BGNPF) with blue and red double-color emitting samples were prepared via a solid-state method in a reductive atmosphere. Their crystal structure and cationic sites were identified in light of X-ray diffraction pattern Rietveld refinement. Three different Ba(2+) sites, coordinated by six O atoms referred to as Ba1, two F and five O atoms as Ba2, and two F and six O atoms as Ba3, were partially substituted by Eu(2+). Photoluminescence emission (PL) and excitation (PLE) spectra of phosphor BGNPF:Eu(2+) along with the lifetimes were characterized at the liquid helium temperature (LHT), which further confirm the existence of three Eu(2+) emitting centers resulting in 436, 480, and 640 nm emission from the 5d → 4f transitions of Eu(2+) in three different Ba(2+) crystallographic sites. These emissions overlap with the absorption spectra of carotenoids and chlorophylls from plants, which could directly promote the photosynthesis. Temperature-dependent PL spectra were used to investigate the thermal stability of phosphor, which indicates that the PL intensity of BGNPF:0.9% Eu(2+) with optimal composition at 150 °C still keeps 60% of its PL intensity at room temperature, in which blue emission has higher thermal-stability than the red emission. Furthermore, the approaching white LED devices have also been manufactured with a 365 nm n-UV LED chip and present phosphor, which make operators more comfortable than that of the plant growth purple emitting LEDs system composed of blue and red light. Results indicate that this phosphor is an attractive dual-responsive candidate phosphor in the application n-UV light-excited white LEDs for plant growth.

  1. Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements – Part I: MODIS brightness temperatures in the thermal infrared

    Directory of Open Access Journals (Sweden)

    T. Fauchez

    2017-07-01

    Full Text Available This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR brightness temperatures (BTs at the top of the atmosphere (TOA as a function of spatial resolution from 50 m to 10 km. A realistic 3-D cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloud-top and base altitudes at 10 and 12 km, respectively, consisting of aggregate column crystals of Deff = 20 µm, and 3-D thermal infrared radiative transfer (RT is simulated with the 3DMCPOL code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB and the (ii horizontal radiative transport (HRT leading to the independent pixel approximation error (IPAE. A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatial-resolution results (above ∼ 250 m with averaged values of up to 5–7 K, while the IPAE mainly impacts the high-spatial-resolution results (below ∼ 250 m with average values of up to 1–2 K. A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 m. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal infrared. For off-nadir observations, the average total effect is increased and the minimum is shifted to coarser spatial

  2. Scale Dependence of Cirrus Horizontal Heterogeneity Effects on TOA Measurements. Part I; MODIS Brightness Temperatures in the Thermal Infrared

    Science.gov (United States)

    Fauchez, Thomas; Platnick, Steven; Meyer, Kerry; Cornet, Celine; Szczap, Frederic; Varnai, Tamas

    2017-01-01

    This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR) brightness temperatures (BTs) at the top of the atmosphere (TOA) as a function of spatial resolution from 50 meters to 10 kilometers. A realistic 3-D (three-dimensional) cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloudtop and base altitudes at 10 and 12 kilometers, respectively, consisting of aggregate column crystals of D (sub eff) equals 20 microns), and 3-D thermal infrared radiative transfer (RT) is simulated with the 3DMCPOL (3-D Monte Carlo Polarized) code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D (one-dimensional) RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i) the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB); and the (ii) horizontal radiative transport (HRT) leading to the independent pixel approximation error (IPAE). A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatial resolution results (above approximately 250 meters), with averaged values of up to 5-7 K (thousand), while the IPAE mainly impacts the high-spatial resolution results (below approximately 250 meters) with average values of up to 1-2 K (thousand). A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 meters. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal

  3. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    Science.gov (United States)

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.

  4. Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential.

    Science.gov (United States)

    Yang, Linlin; Li, Nianbei; Li, Baowen

    2014-12-01

    The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.

  5. Ballistic thermal conductance limited by phonon roughness scattering : A comparison of power-law and Gaussian roughness

    NARCIS (Netherlands)

    Palasantzas, G

    2004-01-01

    In this work, we have investigated the influence of power-law roughness on the ballistic thermal conductance K-TH for a nanosized beam adiabatically connected between two heat reservoirs. The sideways wall beam roughness is assumed to be power-law type, which is described by the roughness amplitude

  6. Thermal tolerance and preference of exploited turbinid snails near their range limit in a global warming hotspot.

    Science.gov (United States)

    Lah, Roslizawati Ab; Benkendorff, Kirsten; Bucher, Daniel

    2017-02-01

    Predicted global climate change has prompted numerous studies of thermal tolerances of marine species. The upper thermal tolerance is unknown for most marine species, but will determine their vulnerability to ocean warming. Gastropods in the family Turbinidae are widely harvested for human consumption. To investigate the responses of turbinid snails to future conditions we determined critical thermal maxima (CTMax) and preferred temperatures of Turbo militaris and Lunella undulata from the tropical-temperate overlap region of northern New South Wales, on the Australian east coast. CTMax were determined at two warming rates: 1°C/30min and 1°C/12h. The number of snails that lost attachment to the tank wall was recorded at each temperature increment. At the faster rate, T. militaris had a significantly higher CTMax (34.0°C) than L. undulata (32.2°C). At the slower rate the mean of both species was lower and there was no significant difference between them (29.4°C for T. militaris and 29.6°C for L. undulata). This is consistent with differences in thermal inertia possibly allowing animals to tolerate short periods at higher temperatures than is possible during longer exposure times, but other mechanisms are not discounted. The thermoregulatory behaviour of the turban snails was determined in a horizontal thermal gradient. Both species actively sought out particular temperatures along the gradient, suggesting that behavioural responses may be important in ameliorating short-term temperature changes. The preferred temperatures of both species were higher at night (24.0°C and 26.0°C) than during the day (22.0°C and 23.9°C). As the snails approached their preferred temperature, net hourly displacement decreased. Preferred temperatures were within the average seasonal seawater temperature range in this region. However, with future predicted water temperature trends, the species could experience increased periods of thermal stress, possibly exceeding CTMax and

  7. PU.1 Expression in T Follicular Helper Cells Limits CD40L-Dependent Germinal Center B Cell Development.

    Science.gov (United States)

    Awe, Olufolakemi; Hufford, Matthew M; Wu, Hao; Pham, Duy; Chang, Hua-Chen; Jabeen, Rukhsana; Dent, Alexander L; Kaplan, Mark H

    2015-10-15

    PU.1 is an ETS family transcription factor that is important for the development of multiple hematopoietic cell lineages. Previous work demonstrated a critical role for PU.1 in promoting Th9 development and in limiting Th2 cytokine production. Whether PU.1 has functions in other Th lineages is not clear. In this study, we examined the effects of ectopic expression of PU.1 in CD4(+) T cells and observed decreased expression of genes involved with the function of T follicular helper (Tfh) cells, including Il21 and Tnfsf5 (encoding CD40L). T cells from conditional mutant mice that lack expression of PU.1 in T cells (Sfpi1(lck-/-)) demonstrated increased production of CD40L and IL-21 in vitro. Following adjuvant-dependent or adjuvant-independent immunization, we observed that Sfpi1(lck-/-) mice had increased numbers of Tfh cells, increased germinal center B cells (GCB cells), and increased Ab production in vivo. This correlated with increased expression of IL-21 and CD40L in Tfh cells from Sfpi1(lck-/-) mice compared with control mice. Finally, although blockade of IL-21 did not affect GCB cells in Sfpi1(lck-/-) mice, anti-CD40L treatment of immunized Sfpi1(lck-/-) mice decreased GCB cell numbers and Ag-specific Ig concentrations. Together, these data indicate an inhibitory role for PU.1 in the function of Tfh cells, germinal centers, and Tfh-dependent humoral immunity. Copyright © 2015 by The American Association of Immunologists, Inc.

  8. Simulation of Field Dependence of Critical Current Densities of Bulk High Tc Superconducting Materials regarding Thermally Activated Flux Motion

    Science.gov (United States)

    Santosh, M.; Naik, S. Pavan Kumar; Koblischka, M. R.

    2017-07-01

    In the upcoming generation, bulk high temperature superconductors (HTS) will play a crucial and a promising role in numerous industrial applications ranging from Maglev trains to magnetic resonance imaging, etc. Especially, the bulk HTS as permanent magnets are suitable due to the fact that they can trap magnetic fields being several orders of magnitude higher than those of the best hard ferromagnets. The bulk HTS LREBa2Cu3O7-δ (LREBCO or LRE-123, LRE: Y, Gd, etc.,) materials could obtain very powerful compact superconducting super-magnets, which can be operated at the cheaper liquid nitrogen temperature or below due to higher critical temperatures (i.e., ∼90 K). As a result, the new advanced technology can be utilized in a more attractive manner for a variety of technological and medical applications which have the capacity to revolutionize the field. An understanding of the magnetic field dependence of the critical current density (J c(H)) is important to develop better adapted materials. To achieve this goal, a variety of Jc (H) behaviours of bulk LREBCO samples were modelled regarding thermally activated flux motion. In essence, the Jc (H) curves follows a certain criterion where an exponential model is applied. However, to fit the complete Jc (H) curve of the LRE-123 samples an unique model is necessary to explain the behavior at low and high fields. The modelling of the various superconducting materials could be understood in terms of the pinning mechanisms.

  9. Microencapsulated Phase Change Materials in Solar-Thermal Conversion Systems: Understanding Geometry-Dependent Heating Efficiency and System Reliability.

    Science.gov (United States)

    Zheng, Zhaoliang; Chang, Zhuo; Xu, Guang-Kui; McBride, Fiona; Ho, Alexandra; Zhuola, Zhuola; Michailidis, Marios; Li, Wei; Raval, Rasmita; Akhtar, Riaz; Shchukin, Dmitry

    2017-01-24

    The performance of solar-thermal conversion systems can be improved by incorporation of nanocarbon-stabilized microencapsulated phase change materials (MPCMs). The geometry of MPCMs in the microcapsules plays an important role for improving their heating efficiency and reliability. Yet few efforts have been made to critically examine the formation mechanism of different geometries and their effect on MPCMs-shell interaction. Herein, through changing the cooling rate of original emulsions, we acquire MPCMs within the nanocarbon microcapsules with a hollow structure of MPCMs (h-MPCMs) or solid PCM core particles (s-MPCMs). X-ray photoelectron spectroscopy and atomic force microscopy reveals that the capsule shell of the h-MPCMs is enriched with nanocarbons and has a greater MPCMs-shell interaction compared to s-MPCMs. This results in the h-MPCMs being more stable and having greater heat diffusivity within and above the phase transition range than the s-MPCMs do. The geometry-dependent heating efficiency and system stability may have important and general implications for the fundamental understanding of microencapsulation and wider breadth of heating generating systems.

  10. Extended Kalman filter method for state of charge estimation of vanadium redox flow battery using thermal-dependent electrical model

    Science.gov (United States)

    Xiong, Binyu; Zhao, Jiyun; Wei, Zhongbao; Skyllas-Kazacos, Maria

    2014-09-01

    State of charge (SOC) estimation is a key issue for battery management since an accurate estimation method can ensure safe operation and prevent the over-charge/discharge of a battery. Traditionally, open circuit voltage (OCV) method is utilized to estimate the stack SOC and one open flow cell is needed in each battery stack [1,2]. In this paper, an alternative method, extended Kalman filter (EKF) method, is proposed for SOC estimation for VRBs. By measuring the stack terminal voltages and applied currents, SOC can be predicted with a state estimator instead of an additional open circuit flow cell. To implement EKF estimator, an electrical model is required for battery analysis. A thermal-dependent electrical circuit model is proposed to describe the charge/discharge characteristics of the VRB. Two scenarios are tested for the robustness of the EKF. For the lab testing scenarios, the filtered stack voltage tracks the experimental data despite the model errors. For the online operation, the simulated temperature rise is observed and the maximum SOC error is within 5.5%. It is concluded that EKF method is capable of accurately predicting SOC using stack terminal voltages and applied currents in the absence of an open flow cell for OCV measurement.

  11. T1 and T2 temperature dependence of female human breast adipose tissue at 1.5 T : groundwork for monitoring thermal therapies in the breast

    NARCIS (Netherlands)

    Baron, Paul; Deckers, RHR; Knuttel, Floor M.; Bartels, LW

    2015-01-01

    The T-1 and T-2 temperature dependence of female breast adipose tissue was investigated at 1.5 T in order to evaluate the applicability of relaxation-based MR thermometry in fat for the monitoring of thermal therapies in the breast. Relaxation times T-1, T-2 and T-2TSE (the apparent T-2 measured

  12. Red blood cell alloimmunization in transfusion-dependent Egyptian patients with thalassemia in a limited donor exposure program.

    Science.gov (United States)

    el-Danasoury, Azza S; Eissa, Doaa G; Abdo, Reham M; Elalfy, Mohsen S

    2012-01-01

    Thalassemia is considered the most common hemoglobinopathy in Egypt and is one of its major health problems. Lifelong red blood cell (RBC) transfusion remains the main treatment for severe forms; however, RBC alloimmunization results as a complication of regular transfusions due to repeated exposure to foreign antigens. The objective was to compare the frequency of alloantibodies in a group of patients in a limited donor exposure program (LDEP) with those receiving RBCs from multiple donors in Egyptian transfusion-dependent patients with thalassemia. A total of 235 regularly transfused patients with thalassemia were studied, 36 of which were on LDEP. All patients were investigated for the presence of RBC autoantibodies and alloantibodies, followed by antibody identification for positive patients. Forty-six (19.5%) patients developed RBC alloantibodies. The most common clinically significant alloantibodies were directed against antigens in the Kell and Rh systems. Development of alloantibodies was associated with older age, higher transfusion frequency, and splenectomy. A trend toward lower alloimmunization was elicited in the LDEP group, where 8.3% (3/36) patients were alloimmunized compared to 21.6% (43/199) in the non-LDEP one (p=0.057). Examination of donor RBCs for presence of Kell and Rh(E) antigens before transfusion can help decrease RBC alloimmunization. Further larger studies are required to assess the frequency of alloantibody production in patients on LDEP. © 2011 American Association of Blood Banks.

  13. A p53-dependent response limits epidermal stem cell functionality and organismal size in mice with short telomeres.

    Directory of Open Access Journals (Sweden)

    Ignacio Flores

    Full Text Available Telomere maintenance is essential to ensure proper size and function of organs with a high turnover. In particular, a dwarf phenotype as well as phenotypes associated to premature loss of tissue regeneration, including the skin (hair loss, hair graying, decreased wound healing, are found in mice deficient for telomerase, the enzyme responsible for maintaining telomere length. Coincidental with the appearance of these phenotypes, p53 is found activated in several tissues from these mice, where is thought to trigger cellular senescence and/or apoptotic responses. Here, we show that p53 abrogation rescues both the small size phenotype and restitutes the functionality of epidermal stem cells (ESC of telomerase-deficient mice with dysfunctional telomeres. In particular, p53 ablation restores hair growth, skin renewal and wound healing responses upon mitogenic induction, as well as rescues ESCmobilization defects in vivo and defective ESC clonogenic activity in vitro. This recovery of ESC functions is accompanied by a downregulation of senescence markers and an increased proliferation in the skin and kidney of telomerase-deficient mice with critically short telomeres without changes in apoptosis rates. Together, these findings indicate the existence of a p53-dependent senescence response acting on stem/progenitor cells with dysfunctional telomeres that is actively limiting their contribution to tissue regeneration, thereby impinging on tissue fitness.

  14. Thermal onset of cellular and endocrine stress responses correspond to ecological limits in brook trout, an iconic cold-water fish.

    Science.gov (United States)

    Chadwick, Joseph G; Nislow, Keith H; McCormick, Stephen D

    2015-01-01

    Climate change is predicted to change the distribution and abundance of species, yet underlying physiological mechanisms are complex and methods for detecting populations at risk from rising temperature are poorly developed. There is increasing interest in using physiological mediators of the stress response as indicators of individual and population-level response to environmental stressors. Here, we use laboratory experiments to show that the temperature thresholds in brook trout (Salvelinus fontinalis) for increased gill heat shock protein-70 (20.7°C) and plasma glucose (21.2°C) are similar to their proposed thermal ecological limit of 21.0°C. Field assays demonstrated increased plasma glucose, cortisol and heat shock protein-70 concentrations at field sites where mean daily temperature exceeded 21.0°C. Furthermore, population densities of brook trout were lowest at field sites where temperatures were warm enough to induce a stress response, and a co-occurring species with a higher thermal tolerance showed no evidence of physiological stress at a warm site. The congruence of stress responses and proposed thermal limits supports the use of these thresholds in models of changes in trout distribution under climate change scenarios and suggests that the induction of the stress response by elevated temperature may play a key role in driving the distribution of species.

  15. A Comparison of Simple Methods to Incorporate Material Temperature Dependency in the Green's Function Method for Estimating Transient Thermal Stresses in Thick-Walled Power Plant Components.

    Science.gov (United States)

    Rouse, James; Hyde, Christopher

    2016-01-06

    The threat of thermal fatigue is an increasing concern for thermal power plant operators due to the increasing tendency to adopt "two-shifting" operating procedures. Thermal plants are likely to remain part of the energy portfolio for the foreseeable future and are under societal pressures to generate in a highly flexible and efficient manner. The Green's function method offers a flexible approach to determine reference elastic solutions for transient thermal stress problems. In order to simplify integration, it is often assumed that Green's functions (derived from finite element unit temperature step solutions) are temperature independent (this is not the case due to the temperature dependency of material parameters). The present work offers a simple method to approximate a material's temperature dependency using multiple reference unit solutions and an interpolation procedure. Thermal stress histories are predicted and compared for realistic temperature cycles using distinct techniques. The proposed interpolation method generally performs as well as (if not better) than the optimum single Green's function or the previously-suggested weighting function technique (particularly for large temperature increments). Coefficients of determination are typically above 0 . 96 , and peak stress differences between true and predicted datasets are always less than 10 MPa.

  16. Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices

    Science.gov (United States)

    Li, Zhe; Ho Chiu, Kar; Shahid Ashraf, Raja; Fearn, Sarah; Dattani, Rajeev; Cheng Wong, Him; Tan, Ching-Hong; Wu, Jiaying; Cabral, João T.; Durrant, James R.

    2015-10-01

    Morphological stability is a key requirement for outdoor operation of organic solar cells. We demonstrate that morphological stability and lifetime of polymer/fullerene based solar cells under thermal stress depend strongly on the substrate interface on which the active layer is deposited. In particular, we find that the stability of benchmark PCDTBT/PCBM solar cells under modest thermal stress is substantially increased in inverted solar cells employing a ZnO substrate compared to conventional devices employing a PEDOT:PSS substrate. This improved stability is observed to correlate with PCBM nucleation at the 50 nm scale, which is shown to be strongly influenced by different substrate interfaces. Employing this approach, we demonstrate remarkable thermal stability for inverted PCDTBT:PC70BM devices on ZnO substrates, with negligible (efficiency over 160 h under 85 °C thermal stress and minimal thermally induced “burn-in” effect. We thus conclude that inverted organic solar cells, in addition to showing improved environmental stability against ambient humidity exposure as widely reported previously, can also demonstrate enhanced morphological stability. As such we show that the choice of suitable substrate interfaces may be a key factor in achieving prolonged lifetimes for organic solar cells under thermal stress conditions.

  17. Influence of temporal noise on the skin blood flow measurements performed by cooled thermal imaging camera: limit possibilities within each physiological frequency range

    Science.gov (United States)

    Sagaidachnyi, A. A.; Volkov, I. U.; Fomin, A. V.

    2016-04-01

    This paper describes limit possibilities of modern cooled thermal imaging cameras as a tool for estimation of blood flow oscillations at the surface of living body. Skin temperature oscillations, as we assumed, are a consequence of the blood flow oscillations. We considered the temperature sensitivity 0.01-0.02 °C as a typical for the most of modern cooled long wave thermal imaging cameras. Fourier filter used to investigate the temperature signal separately within endothelial, neurogenic, myogenic, respiratory and cardiac frequency ranges. The level of temporal noise has been estimated during measurements of no living body with stabilized temperature ~ 24°C. The level of temperature oscillations has been calculated for the group of healthy subjects within each frequency range. Thus, we were able to determine signal-to-noise ratio within frequency band [0.001, 1] Hz. As a result, we determine that skin temperature oscillations measured by thermal imaging camera with sensitivity 0.02°C have the upper frequency limit ~ 0.2 Hz. In other words, within the respiratory and cardiac frequency ranges of blood flow oscillations the noise level exceeds signal one, and temperature measurements at the skin surface are practically useless. The endothelial, neurogenic and myogenic components of the temperature oscillations contain ~98% of the total spectral power of the signal. We have plot the empirical extrapolated curve of sensitivity of thermal imaging camera vs. frequency of the temperature oscillations. The data analysis shows that measurements of skin temperature oscillations within respiratory and cardiac ranges require the temperature sensitivity at least ~ 0.01°C and 0.001°C, respectively.

  18. Modeling of thermal lensing in a [1 1 1]-cut Nd:YAG rod with temperature-dependent parameters and different pumping profiles

    Science.gov (United States)

    Bričkus, D.; Dement'ev, A. S.

    2017-05-01

    Temperature dependences of the thermo-optical coefficients of YAG crystals are often neglected when thermal lensing in laser rods is investigated, though their influence is very significant. It is especially significant for transversally non-uniform thermal loading. An analytical solution of the heat transfer equation with only the radial heat flow is found in the integral form, which is very convenient for numerical simulations. Uniform, top-hat, parabolic, Gaussian, super-Gaussian and annular heat source distributions are used in the calculations. The generalization of the thermally-induced refractive index change for long enough [1 1 1]-cut YAG rods to the case of temperature-dependent YAG parameters is developed and applied to the calculation of the corresponding optical path differences. Different definitions of the optical power of the aberrated thermal lens (TL) are discussed in detail. It is shown that for each of the heat source distributions, the temperature dependences of the YAG parameters significantly increase (1.5-1.8 times) the paraxial optical power of the induced TL.

  19. TiO2 films annealing temperature-dependent properties in terms of the Amlouk-Boubaker opto-thermal expansivity ψAB

    Science.gov (United States)

    Amlouk, A.; Boubaker, K.; El Mir, L.; Amlouk, M.

    2011-02-01

    In this study, TiO2 films were grown at room temperature by sol-gel process using titanium (IV)-isopropylat as precursor. XRD, EDS and MEB analyses proved that an eventual annealing treatment caused the TiO2 amorphous phase to shift to a crystalline anatase phase. Optical measurements were carried out via absorbance spectra in 500-2500 nm wavelength domain. From these optical measurements, the temperature-dependent conjoint optical and thermal properties were deduced using the Amlouk-Boubaker opto-thermal expansivity ψAB.

  20. An Investigation into the Effects of Interface Stress and Interfacial Arrangement on Temperature Dependent Thermal Properties of a Biological and a Biomimetic Material

    Energy Technology Data Exchange (ETDEWEB)

    Tomar, Vikas [Purdue Univ., West Lafayette, IN (United States)

    2015-01-12

    A significant effort in the biomimetic materials research is on developing materials that can mimic and function in the same way as biological tissues, on bio-inspired electronic circuits, on bio-inspired flight structures, on bio-mimetic materials processing, and on structural biomimetic materials, etc. Most structural biological and biomimetic material properties are affected by two primary factors: (1) interfacial interactions between an organic and an inorganic phase usually in the form of interactions between an inorganic mineral phase and organic protein network; and (2) structural arrangement of the constituents. Examples are exoskeleton structures such as spicule, nacre, and crustacean exoskeletons. A significant effort is being directed towards making synthetic biomimetic materials based on a manipulation of the above two primary factors. The proposed research is based on a hypothesis that in synthetic materials with biomimetic morphology thermal conductivity, k, (how fast heat is carried away) and thermal diffusivity, D, (how fast a material’s temperature rises: proportional to the ratio of k and heat capacity) can be engineered to be either significantly low or significantly high based on a combination of chosen interface orientation and interfacial arrangement in comparison to conventional material microstructures with the same phases and phase volume fractions. METHOD DEVELOPMENT 1. We have established a combined Raman spectroscopy and nanomechanical loading based experimental framework to perform environment (liquid vs. air vs. vacuum) dependent and temperature dependent (~1000 degree-C) in-situ thermal diffusivity measurements in biomaterials at nanoscale to micron scale along with the corresponding analytical theoretic calculations. (Zhang and Tomar, 2013) 2. We have also established a new classical molecular simulation based framework to measure thermal diffusivity in biomolecular interfaces. We are writing a publication currently (Qu and Tomar

  1. Temperature dependence of the thermal diffusivity of GaAs in the 100-305 K range measured by the pulsed photothermal displacement technique

    Science.gov (United States)

    Soltanolkotabi, M.; Bennis, G. L.; Gupta, R.

    1999-01-01

    We have measured the variation of the value of the thermal diffusivity of semi-insulating GaAs in the 100-305 K range. The method used is the pulsed photothermal displacement technique. This is a noncontact technique, and the value of the thermal diffusivity is derived from the temporal evolution of the signal rather than its amplitude. This makes the technique less susceptible to uncertainties. We find that the temperature dependence of the thermal conductivity of semi-insulating GaAs follows a power law as T-1.62, in disagreement with results obtained previously. Possible reasons for the deviation within this very important intermediate temperature range are discussed.

  2. Honeybee colony thermoregulation--regulatory mechanisms and contribution of individuals in dependence on age, location and thermal stress.

    Directory of Open Access Journals (Sweden)

    Anton Stabentheiner

    2010-01-01

    Full Text Available Honeybee larvae and pupae are extremely stenothermic, i.e. they strongly depend on accurate regulation of brood nest temperature for proper development (33-36 degrees C. Here we study the mechanisms of social thermoregulation of honeybee colonies under changing environmental temperatures concerning the contribution of individuals to colony temperature homeostasis. Beside migration activity within the nest, the main active process is "endothermy on demand" of adults. An increase of cold stress (cooling of the colony increases the intensity of heat production with thoracic flight muscles and the number of endothermic individuals, especially in the brood nest. As endothermy means hard work for bees, this eases much burden of nestmates which can stay ectothermic. Concerning the active reaction to cold stress by endothermy, age polyethism is reduced to only two physiologically predetermined task divisions, 0 to approximately 2 days and older. Endothermic heat production is the job of bees older than about two days. They are all similarly engaged in active heat production both in intensity and frequency. Their active heat production has an important reinforcement effect on passive heat production of the many ectothermic bees and of the brood. Ectothermy is most frequent in young bees (< approximately 2 days both outside and inside of brood nest cells. We suggest young bees visit warm brood nest cells not only to clean them but also to speed up flight muscle development for proper endothermy and foraging later in their life. Young bees inside brood nest cells mostly receive heat from the surrounding cell wall during cold stress, whereas older bees predominantly transfer heat from the thorax to the cell wall. Endothermic bees regulate brood comb temperature more accurately than local air temperature. They apply the heat as close to the brood as possible: workers heating cells from within have a higher probability of endothermy than those on the comb

  3. Finnigan ion trap mass spectrometer detection limits and thermal energy analyzer interface status report and present capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Alcaraz, A.; Andresen, B.; Martin, W.

    1990-10-18

    A new Finnigan ion trap mass spectrometer was purchased and installed at LLNL. Over a period of several months the instrument was tested under a variety of conditions utilizing a capillary gas chromatography interface which allowed separated organic compounds to be carried directly into the ion source of the mass spectrometer. This direct interface allowed maximum analytical sensitivity. A variety of critical tests were performed in order to optimize the sensitivity of the system under a variety of analysis conditions. These tests altered the critical time cycles of the ionization, ion trapping, and detection. Various carrier gas pressures were also employed in order to ascertain the overall sensitivity of the instrument. In addition we have also interfaced a thermal energy analyzer (TEA) to the gas chromatograph in order to simultaneously detect volatile nitrogen containing compounds while mass spectral data is being acquired. This is the first application at this laboratory of simultaneous ultra-trace detections while utilizing two orthogonal analytical techniques. In particular, explosive-related compound and/or residues are of interest to the general community in water, soil and gas sampler. In this paper are highlighted a few examples of the analytical power of this new GC-TEA-ITMS technology.

  4. Graphene thermal flux transistor.

    Science.gov (United States)

    Shafranjuk, S E

    2016-11-24

    Insufficient flexibility of existing approaches to controlling the thermal transport in atomic monolayers limits their capability for use in many applications. Here, we examine the means of electrode doping to control the thermal flux Q due to phonons propagating along the atomic monolayer. We found that the frequency of the electron-restricted phonon scattering strongly depends on the concentration nC. of the electric charge carriers, established by the electric potentials applied to local gates. As a result of the electrode doping, nC is increased, causing a sharp rise in both the electrical conductivity and Seebeck coefficient, while the thermal conductivity tumbles. Therefore, the effect of the thermal transistor improves the figure of merit of nanoelectronic circuits.

  5. Optimizing the Thermal Read-Out Technique for MIP-Based Biomimetic Sensors: Towards Nanomolar Detection Limits

    Directory of Open Access Journals (Sweden)

    Patrick Wagner

    2013-07-01

    Full Text Available In previous work, the novel heat-transfer method (HTM for the detection of small molecules with Molecularly Imprinted Polymers (MIP-type receptors was presented. In this study we focus on optimization of this sensor performance, with as final aim to lower the detection limit by reducing the noise level. It was determined that the noise originates foremost from the power supply, which can be controlled by varying the PID parameters. Therefore, the effect of the individual parameters was evaluated by tuning P, I and D separately at a temperature of 37 °C, giving a first indication of the optimal configuration. Next, a temperature profile was programmed and the standard deviation of the heat-transfer resistance over the entire regime was studied for a set of parameters. The optimal configuration, P1-I6-D0, reduced the noise level with nearly a factor of three compared to the original parameters of P10-I5-D0. With the optimized settings, the detection of L-nicotine in buffer solutions was studied and the detection limit improved significantly from 100 nM to 35 nM. Summarizing, optimization of the PID parameters and thereby improving the detection limit is a key parameter for first applications of the HTM-method for MIP receptors in analytical research.

  6. Optimizing the thermal read-out technique for MIP-based biomimetic sensors: towards nanomolar detection limits.

    Science.gov (United States)

    Geerets, Bram; Peeters, Marloes; van Grinsven, Bart; Bers, Karolien; de Ceuninck, Ward; Wagner, Patrick

    2013-07-16

    In previous work, the novel heat-transfer method (HTM) for the detection of small molecules with Molecularly Imprinted Polymers (MIP)-type receptors was presented. In this study we focus on optimization of this sensor performance, with as final aim to lower the detection limit by reducing the noise level. It was determined that the noise originates foremost from the power supply, which can be controlled by varying the PID parameters. Therefore, the effect of the individual parameters was evaluated by tuning P, I and D separately at a temperature of 37 °C, giving a first indication of the optimal configuration. Next, a temperature profile was programmed and the standard deviation of the heat-transfer resistance over the entire regime was studied for a set of parameters. The optimal configuration, P1-I6-D0, reduced the noise level with nearly a factor of three compared to the original parameters of P10-I5-D0. With the optimized settings, the detection of L-nicotine in buffer solutions was studied and the detection limit improved significantly from 100 nM to 35 nM. Summarizing, optimization of the PID parameters and thereby improving the detection limit is a key parameter for first applications of the HTM-method for MIP receptors in analytical research.

  7. Review of the mathematical functions used to model the temperature dependence of electrical and thermal conductivities of biological tissue in radiofrequency ablation.

    Science.gov (United States)

    Trujillo, Macarena; Berjano, Enrique

    2013-09-01

    Although theoretical modelling is widely used to study different aspects of radiofrequency ablation (RFA), its utility is directly related to its realism. An important factor in this realism is the use of mathematical functions to model the temperature dependence of thermal (k) and electrical (σ) conductivities of tissue. Our aim was to review the piecewise mathematical functions most commonly used for modelling the temperature dependence of k and σ in RFA computational modelling. We built a hepatic RFA theoretical model of a cooled electrode and compared lesion dimensions and impedance evolution with combinations of mathematical functions proposed in previous studies. We employed the thermal damage contour D63 to compute the lesion dimension contour, which corresponds to Ω = 1, Ω being local thermal damage assessed by the Arrhenius damage model. The results were very similar in all cases in terms of impedance evolution and lesion size after 6 min of ablation. Although the relative differences between cases in terms of time to first roll-off (abrupt increase in impedance) were as much as 12%, the maximum relative differences in terms of the short lesion (transverse) diameter were below 3.5%. The findings suggest that the different methods of modelling temperature dependence of k and σ reported in the literature do not significantly affect the computed lesion diameter.

  8. Cryo-thermal therapy elicits potent anti-tumor immunity by inducing extracellular Hsp70-dependent MDSC differentiation

    Science.gov (United States)

    Zhu, Jun; Zhang, Yan; Zhang, Aili; He, Kun; Liu, Ping; Xu, Lisa X.

    2016-01-01

    Achieving control of metastatic disease is a long-sought goal in cancer therapy. Treatments that encourage a patient’s own immune system are bringing new hopes in reaching such a goal. In clinic, local hyperthermia and cryoablation have been explored to induce anti-tumor immune responses against tumors. We have also developed a novel therapeutic modality of cryo-thermal treatment by alternating liquid nitrogen (LN2) cooling and radio frequency (RF) heating, and better therapeutic effect was achieved in treating metastatic cancer in animal model. In this study, we investigated the mechanism of systemic immune response elicited by cryo-thermal therapy. In the 4T1 murine mammary carcinoma model, we found that local cryo-thermal therapy resulted in a considerable reduction of distant lung metastases, and improved long-term survival. Moreover, results of tumor re-challenge experiments indicated generation of a strong tumor-specific immune memory after the local treatment of primary tumors. Our further study indicated that cryo-thermal therapy caused an elevated extracellular release of Hsp70. Subsequently, Hsp70 induced differentiation of MDSCs into mature DCs, contributing to the relief of MDSCs-mediated immunosuppression and ultimately the activation of strong anti-tumor immune response. Our findings reveal new insight into the mechanism of robust therapeutic effects of cryo-thermal therapy against metastatic cancers. PMID:27256519

  9. Cryo-thermal therapy elicits potent anti-tumor immunity by inducing extracellular Hsp70-dependent MDSC differentiation

    Science.gov (United States)

    Zhu, Jun; Zhang, Yan; Zhang, Aili; He, Kun; Liu, Ping; Xu, Lisa X.

    2016-06-01

    Achieving control of metastatic disease is a long-sought goal in cancer therapy. Treatments that encourage a patient’s own immune system are bringing new hopes in reaching such a goal. In clinic, local hyperthermia and cryoablation have been explored to induce anti-tumor immune responses against tumors. We have also developed a novel therapeutic modality of cryo-thermal treatment by alternating liquid nitrogen (LN2) cooling and radio frequency (RF) heating, and better therapeutic effect was achieved in treating metastatic cancer in animal model. In this study, we investigated the mechanism of systemic immune response elicited by cryo-thermal therapy. In the 4T1 murine mammary carcinoma model, we found that local cryo-thermal therapy resulted in a considerable reduction of distant lung metastases, and improved long-term survival. Moreover, results of tumor re-challenge experiments indicated generation of a strong tumor-specific immune memory after the local treatment of primary tumors. Our further study indicated that cryo-thermal therapy caused an elevated extracellular release of Hsp70. Subsequently, Hsp70 induced differentiation of MDSCs into mature DCs, contributing to the relief of MDSCs-mediated immunosuppression and ultimately the activation of strong anti-tumor immune response. Our findings reveal new insight into the mechanism of robust therapeutic effects of cryo-thermal therapy against metastatic cancers.

  10. Thermal-maturity limit for primary thermogenic-gas generation from humic coals as determined by hydrous pyrolysis

    Science.gov (United States)

    Lewan, Michael; Kotarba, M.J.

    2014-01-01

    Hydrous-pyrolysis experiments at 360°C (680°F) for 72 h were conducted on 53 humic coals representing ranks from lignite through anthracite to determine the upper maturity limit for hydrocarbon-gas generation from their kerogen and associated bitumen (i.e., primary gas generation). These experimental conditions are below those needed for oil cracking to ensure that generated gas was not derived from the decomposition of expelled oil generated from some of the coals (i.e., secondary gas generation). Experimental results showed that generation of hydrocarbon gas ends before a vitrinite reflectance of 2.0%. This reflectance is equivalent to Rock-Eval maximum-yield temperature and hydrogen indices (HIs) of 555°C (1031°F) and 35 mg/g total organic carbon (TOC), respectively. At these maturity levels, essentially no soluble bitumen is present in the coals before or after hydrous pyrolysis. The equivalent kerogen atomic H/C ratio is 0.50 at the primary gas-generation limit and indicates that no alkyl moieties are remaining to source hydrocarbon gases. The convergence of atomic H/C ratios of type-II and -I kerogen to this same value at a reflectance of indicates that the primary gas-generation limits for humic coal and type-III kerogen also apply to oil-prone kerogen. Although gas generation from source rocks does not exceed vitrinite reflectance values greater than , trapped hydrocarbon gases can remain stable at higher reflectance values. Distinguishing trapped gas from generated gas in hydrous-pyrolysis experiments is readily determined by of the hydrocarbon gases when a -depleted water is used in the experiments. Water serves as a source of hydrogen in hydrous pyrolysis and, as a result, the use of -depleted water is reflected in the generated gases but not pre-existing trapped gases.

  11. Analysis of Queue-Length Dependent Vacations and P-Limited Service in BMAP/G/1/N Systems: Stationary Distributions and Optimal Control

    Directory of Open Access Journals (Sweden)

    A. D. Banik

    2013-01-01

    Full Text Available We consider a finite-buffer single server queueing system with queue-length dependent vacations where arrivals occur according to a batch Markovian arrival process (BMAP. The service discipline is P-limited service, also called E-limited with limit variation (ELV where the server serves until either the system is emptied or a randomly chosen limit of L customers has been served. Depending on the number of customers present in the system, the server will monitor his vacation times. Queue-length distributions at various epochs such as before, arrival, arbitrary and after, departure have been obtained. Several other service disciplines like Bernoulli scheduling, nonexhaustive service, and E-limited service can be treated as special cases of the P-limited service. Finally, the total expected cost function per unit time is considered to determine locally optimal values N* of N or a maximum limit L^* of L^ as the number of customers served during a service period at a minimum cost.

  12. Endogenous functional compounds in Korean native chicken meat are dependent on sex, thermal processing and meat cut.

    Science.gov (United States)

    Jayasena, Dinesh D; Jung, Samooel; Kim, Sun Hyo; Kim, Hyun Joo; Alahakoon, Amali U; Lee, Jun Heon; Jo, Cheorun

    2015-03-15

    In this study the effects of sex, meat cut and thermal processing on the carnosine, anserine, creatine, betaine and carnitine contents of Korean native chicken (KNC) meat were determined. Forty 1-day-old chicks (20 chicks of each sex) from a commercial KNC strain (Woorimatdag™) were reared under similar standard commercial conditions with similar diets, and ten birds of each sex were randomly selected and slaughtered at 14 weeks of age. Raw and cooked meat samples were prepared from both breast and leg meats and analyzed for the aforementioned functional compounds. Female KNCs had significantly higher betaine and creatine contents. The breast meat showed significantly higher carnosine and anserine contents, whereas the leg meat had a higher betaine and carnitine content. The content of all functional compounds was significantly depleted by thermal processing. This study confirms that KNC meat is a good source of the above-mentioned functional compounds, which can be considered attractive nutritional quality factors. However, their concentrations were significantly affected by thermal processing conditions, meat cut and sex. Further experiments are needed to select the best thermal processing method to preserve these functional compounds. © 2014 Society of Chemical Industry.

  13. The effects of acclimation and rates of temperature change on critical thermal limits in Tenebrio molitor (Tenebrionidae) and Cyrtobagous salviniae (Curculionidae).

    Science.gov (United States)

    Allen, Jessica L; Clusella-Trullas, Susana; Chown, Steven L

    2012-05-01

    Critical thermal limits provide an indication of the range of temperatures across which organisms may survive, and the extent of the lability of these limits offers insights into the likely impacts of changing thermal environments on such survival. However, investigations of these limits may be affected by the circumstances under which trials are undertaken. Only a few studies have examined these effects, and typically not for beetles. This group has also not been considered in the context of the time courses of acclimation and its reversal, both of which are important for estimating the responses of species to transient temperature changes. Here we therefore examine the effects of rate of temperature change on critical thermal maxima (CT(max)) and minima (CT(min)), as well as the time course of the acclimation response and its reversal in two beetle species, Tenebrio molitor and Cyrtobagous salviniae. Increasing rates of temperature change had opposite effects on T. molitor and C. salviniae. In T. molitor, faster rates of change reduced both CT(max) (c. 2°C) and CT(min) (c. 3°C), while in C. salviniae faster rates of change increased both CT(max) (c. 6°C) and CT(min) (c. 4°C). CT(max) in T. molitor showed little response to acclimation, while the response to acclimation of CT(min) was most pronounced following exposure to 35°C (from 25°C) and was complete within 24 h. The time course of acclimation of CT(max) in C. salviniae was 2 days when exposed to 36°C (from c. 26°C), while that of CT(min) was less than 3 days when exposed to 18°C. In T. molitor, the time course of reacclimation to 25°C after treatments at 15°C and 35°C at 75% RH was longer than the time course of acclimation, and varied from 3-6 days for CT(max) and 6 days for CT(min). In C. salviniae, little change in CT(max) and CT(min) (molitor and C. salviniae may be restricted in their ability to respond to transient temperature changes at short-time scales, and instead may have to rely on

  14. Effect of smoke evacuation on limiting thermal damage when using the carbon dioxide laser for cutaneous surgery

    Science.gov (United States)

    Waters, Ruth A.; Thomas, J. M.; Clement, Marc; Davies, S.

    1990-06-01

    We have conducted a study of the use of the carbon dioxide (C02) laser for ablation of multiple cutaneous recurrences of melanoma. Lesions of primary malignant melanoma are usually widely excised to try and prevent local recurrence. Despite this, recurrent cutaneous lesions do occur. These lesions may be small and numerous making local excision impractical. Hyperthermic isolated limb perfusion has shown some success in controlling the local disease but this procedure has a significant morbidty, some patients show only a limited response and post-perfusion recurrences are common.1 Also, in some patients, thelesions will not be confined to a limb. No other method of local control has provided an ideal solution and amputation has sometimes been a last resort. We have therefore selected patients for laser ablation if they have had lesions too numerous for local excision, or have had recurrences following perfusion or were otherwise suitable for perfusion. The lesions were vaporized under local or general anaesthesia according to their size and number. The wounds were then left to heal by secondary intention. Simple dry dressings were applied and all patients were discharged home within 24 hours. In total we have treated over 1,500 lesions in 30 patients. The results of the initial study have been very encouraging. The procedure is quick and simple with absent or minimal post-operative pain. Although the incidence of recurrent tumour at a previously lasered site is less than 1%, new tumours may develop at other sites. These are amenable to further laser treatment.

  15. A set of nutrient limitations trigger yeast cell death in a nitrogen-dependent manner during wine alcoholic fermentation.

    Science.gov (United States)

    Duc, Camille; Pradal, Martine; Sanchez, Isabelle; Noble, Jessica; Tesnière, Catherine; Blondin, Bruno

    2017-01-01

    Yeast cell death can occur during wine alcoholic fermentation. It is generally considered to result from ethanol stress that impacts membrane integrity. This cell death mainly occurs when grape musts processing reduces lipid availability, resulting in weaker membrane resistance to ethanol. However the mechanisms underlying cell death in these conditions remain unclear. We examined cell death occurrence considering yeast cells ability to elicit an appropriate response to a given nutrient limitation and thus survive starvation. We show here that a set of micronutrients (oleic acid, ergosterol, pantothenic acid and nicotinic acid) in low, growth-restricting concentrations trigger cell death in alcoholic fermentation when nitrogen level is high. We provide evidence that nitrogen signaling is involved in cell death and that either SCH9 deletion or Tor inhibition prevent cell death in several types of micronutrient limitation. Under such limitations, yeast cells fail to acquire any stress resistance and are unable to store glycogen. Unexpectedly, transcriptome analyses did not reveal any major changes in stress genes expression, suggesting that post-transcriptional events critical for stress response were not triggered by micronutrient starvation. Our data point to the fact that yeast cell death results from yeast inability to trigger an appropriate stress response under some conditions of nutrient limitations most likely not encountered by yeast in the wild. Our conclusions provide a novel frame for considering both cell death and the management of nutrients during alcoholic fermentation.

  16. A set of nutrient limitations trigger yeast cell death in a nitrogen-dependent manner during wine alcoholic fermentation.

    Directory of Open Access Journals (Sweden)

    Camille Duc

    Full Text Available Yeast cell death can occur during wine alcoholic fermentation. It is generally considered to result from ethanol stress that impacts membrane integrity. This cell death mainly occurs when grape musts processing reduces lipid availability, resulting in weaker membrane resistance to ethanol. However the mechanisms underlying cell death in these conditions remain unclear. We examined cell death occurrence considering yeast cells ability to elicit an appropriate response to a given nutrient limitation and thus survive starvation. We show here that a set of micronutrients (oleic acid, ergosterol, pantothenic acid and nicotinic acid in low, growth-restricting concentrations trigger cell death in alcoholic fermentation when nitrogen level is high. We provide evidence that nitrogen signaling is involved in cell death and that either SCH9 deletion or Tor inhibition prevent cell death in several types of micronutrient limitation. Under such limitations, yeast cells fail to acquire any stress resistance and are unable to store glycogen. Unexpectedly, transcriptome analyses did not reveal any major changes in stress genes expression, suggesting that post-transcriptional events critical for stress response were not triggered by micronutrient starvation. Our data point to the fact that yeast cell death results from yeast inability to trigger an appropriate stress response under some conditions of nutrient limitations most likely not encountered by yeast in the wild. Our conclusions provide a novel frame for considering both cell death and the management of nutrients during alcoholic fermentation.

  17. Partitioning the metabolic scope: the importance of anaerobic metabolism and implications for the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis

    DEFF Research Database (Denmark)

    Ejbye-Ernst, Rasmus; Michaelsen, Thomas Y.; Tirsgaard, B.

    2016-01-01

    Ongoing climate change is predicted to affect the distribution and abundance of aquatic ectotherms owing to increasing constraints on organismal physiology, in particular involving the metabolic scope (MS) available for performance and fitness. The oxygen- and capacity-limited thermal tolerance...... performance. Our results suggest that without accounting for anaerobic metabolism within the MS, studies involving the OCLTT hypothesis could overestimate the metabolic scope available for sustainable activities and the ability of individuals and species to cope with climate change...... 24.3 and 26.1% in S. aurata and P. reticulata, respectively. These data highlight the importance of taking anaerobic metabolism into account when assessing effects of environmental variation on the MS, because the fraction where anaerobic metabolism occurs is a poor indicator of sustainable aerobic...

  18. Thermal limits on MV x-ray production by bremsstrahlung targets in the context of novel linear accelerators.

    Science.gov (United States)

    Wang, Jinghui; Trovati, Stefania; Borchard, Philipp M; Loo, Billy W; Maxim, Peter G; Fahrig, Rebecca

    2017-12-01

    To study the impact of target geometrical and linac operational parameters, such as target material and thickness, electron beam size, repetition rate, and mean current on the ability of the radiotherapy treatment head to deliver high-dose-rate x-ray irradiation in the context of novel linear accelerators capable of higher repetition rates/duty cycle than conventional clinical linacs. The depth dose in a water phantom without a flattening filter and heat deposition in an x-ray target by 10 MeV pulsed electron beams were calculated using the Monte-Carlo code MCNPX, and the transient temperature behavior of the target was simulated by ANSYS. Several parameters that affect both the dose distribution and temperature behavior were investigated. The target was tungsten with a thickness ranging from 0 to 3 mm and a copper heat remover layer. An electron beam with full width at half maximum (FWHM) between 0 and3 mm and mean current of 0.05-2 mA was used as the primary beam at repetition rates of 100, 200, 400, and 800 Hz. For a 10 MeV electron beam with FWHM of 1 mm, pulse length of 5 μs, by using a thin tungsten target with thickness of 0.2 mm instead of 1 mm, and by employing a high repetition rate of 800 Hz instead of 100 Hz, the maximum dose rate delivered can increase two times from 0.57 to 1.16 Gy/s. In this simple model, the limiting factor on dose rate is the copper heat remover's softening temperature, which was considered to be 500°C in our study. A high dose rate can be obtained by employing thin targets together with high repetition rate electron beams enabled by novel linac designs, whereas the benefit of thin targets is marginal at conventional repetition rates. Next generation linacs used to increase dose rate need different target designs compared to conventional linacs. © 2017 American Association of Physicists in Medicine.

  19. Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells.

    Science.gov (United States)

    Foxman, Ellen F; Storer, James A; Fitzgerald, Megan E; Wasik, Bethany R; Hou, Lin; Zhao, Hongyu; Turner, Paul E; Pyle, Anna Marie; Iwasaki, Akiko

    2015-01-20

    Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33-35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C. Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I-like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C. Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

  20. Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

    Science.gov (United States)

    Atitoaie, Alexandru; Tanasa, Radu; Enachescu, Cristian

    2012-04-01

    Spin crossover compounds are photo-magnetic bistable molecular magnets with two states in thermodynamic competition: the diamagnetic low-spin state and paramagnetic high-spin state. The thermal transition between the two states is often accompanied by a wide hysteresis, premise for possible application of these materials as recording media. In this paper we study the influence of the system's size on the thermal hysteresis loops using Monte Carlo simulations based on an Arrhenius dynamics applied for an Ising like model with long- and short-range interactions. We show that using appropriate boundary conditions it is possible to reproduce both the drop of hysteresis width with decreasing particle size, the hysteresis shift towards lower temperatures and the incomplete transition, as in the available experimental data. The case of larger systems composed by several sublattices is equally treated reproducing the shrinkage of the hysteresis loop's width experimentally observed.

  1. Contribution to the study of the dependence in the limit between various statistics of a sample; Contribution a l'etude des liaisons limites entre differentes statistiques d'un echantillon

    Energy Technology Data Exchange (ETDEWEB)

    Rosengard, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-02-01

    With a view to the investigation of the dependence in the limit between some statistics, we give general definitions of the independence in the limit and some of their properties are investigated. We then give some necessary and sufficient conditions for the independence in the limit between sample mean and orders statistics, in particular quantities and extreme values. For example, we show that, for bounded variance laws, the sample mean and orders statistics, in particular quantities and extreme values. For example, we show that, for bounded variance laws, the sample mean tends to become independent of the extreme values, whereas it is asymptotically dependent on the quantities, with a positive correlation coefficient for which an expression is given. We investigate also the case in which variance is unbounded. (author) [French] Afin d'etudier la liaison limite entre certaines statistiques d'un echantillon, on est amene a donner des definitions generales de l'independance limite, et a en etudier quelques proprietes. On donne ensuite les conditions necessaires et suffisantes pour l'independance limite des statistiques d'ordre, et on etudie la liaison limite entre la moyenne et les statistiques d'ordre, en particulier quantites et valeurs extremes. On montre par exemple, que pour des lois dont la variance est finie, la moyenne tend a devenir independante des valeurs extremes, alors qu'elle est asymptotiquement liee aux quantites, avec un coefficient de correlation positif, dont on donne l'expression. On etudie egalement le cas ou la variance est infinie. (auteur)

  2. Multi-boiling Heat Transfer Analysis of a Convective Straight Fin with Temperature-Dependent Thermal Properties and Internal Heat Generation

    Directory of Open Access Journals (Sweden)

    Gbeminiyi Sobamowo

    2017-10-01

    Full Text Available In this study, by using the finite volume method, the heat transfer in a convective straight fin with temperature-dependent thermal properties and an internal heat generation under multi-boiling heat transfer modes are analyzed. In this regard, the local heat transfer coefficient is considered to vary within a power-law function of temperature. In the present study, the coexistence of all the boiling modes is taken into consideration. The developed heat transfer models and the corresponding numerical solutions are used to investigate the effects of various thermo-geometric parameters on the thermal performance of the longitudinal rectangular fin. The results shows that the fin temperature distribution, the total heat transfer, and the fin efficiency are significantly affected by the thermo-geometric parameters of the fin and the internal heat generation within the fin. The obtained results can provide a platform for improvements in the design of the fin in the heat transfer equipment.

  3. Analysis of Convective Straight and Radial Fins with Temperature-Dependent Thermal Conductivity Using Variational Iteration Method with Comparison with Respect to Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Safa Bozkurt Coşkun

    2007-01-01

    Full Text Available In order to enhance heat transfer between primary surface and the environment, radiating extended surfaces are commonly utilized. Especially in the case of large temperature differences, variable thermal conductivity has a strong effect on performance of such a surface. In this paper, variational iteration method is used to analyze convective straight and radial fins with temperature-dependent thermal conductivity. In order to show the efficiency of variational iteration method (VIM, the results obtained from VIM analysis are compared with previously obtained results using Adomian decomposition method (ADM and the results from finite element analysis. VIM produces analytical expressions for the solution of nonlinear differential equations. However, these expressions obtained from VIM must be tested with respect to the results obtained from a reliable numerical method or analytical solution. This work assures that VIM is a promising method for the analysis of convective straight and radial fin problems.

  4. Integrated Equivalent Circuit and Thermal Model for Simulation of Temperature-Dependent LiFePO4 Battery in Actual Embedded Application

    Directory of Open Access Journals (Sweden)

    Zuchang Gao

    2017-01-01

    Full Text Available A computational efficient battery pack model with thermal consideration is essential for simulation prototyping before real-time embedded implementation. The proposed model provides a coupled equivalent circuit and convective thermal model to determine the state-of-charge (SOC and temperature of the LiFePO4 battery working in a real environment. A cell balancing strategy applied to the proposed temperature-dependent battery model balanced the SOC of each cell to increase the lifespan of the battery. The simulation outputs are validated by a set of independent experimental data at a different temperature to ensure the model validity and reliability. The results show a root mean square (RMS error of 1.5609 × 10−5 for the terminal voltage and the comparison between the simulation and experiment at various temperatures (from 5 °C to 45 °C shows a maximum RMS error of 7.2078 × 10−5.

  5. Crank-Nicholson Scheme for the Estimation of Thermal Disturbance on the Peripheral Tissues of Human Body Subjected to Oscillatory Boundary Condition and Time Dependent Heat Source

    Science.gov (United States)

    Khanday, M. A.; Hussain, Fida

    2015-07-01

    To predict the behaviour of thermal physiology of a finite biological tissue in severe cold climatic conditions, a mathematical model has been established based on Pennes' bio-heat transfer equation with oscillatory boundary condition and time dependent heat source term. Crank-Nicholson scheme has been employed to obtain the solution of the boundary value problem to understand the change in stable temperature profiles at the peripheral tissues of human body subjected to forced convection due to cold. Thermal stress at these regions with respect to different input parameters has been computed under extreme environmental conditions using MATLAB Software. The results have shown a relative significance and provide a reasonable outcome in terms of variable metabolic heat generation and oscillatory heat source. The oscillations of the temperature profiles from the mean temperatures were computed in relation with tissue medium and other physiological parameters.

  6. Dependence of hemostasis indices on external environment nemperature in women with physiological pregnancy accompanied by limitation of liquid intake

    Directory of Open Access Journals (Sweden)

    Zhulina N.V.

    2011-12-01

    Full Text Available The research goal was to study the influence of extremely high temperatures on the hemostasis indices in patients with uncomplicated pregnancies with the concomitant limitation of liquid intake. The research results of hemostasis of pregnant women being hospitalized during the period of spring and summer in 2010 have been analyzed. The differences in the level of hypercoagulation changes of hemostasis in summer and spring have been found to be insignificant. In the platelet link hemostasis in summer of 2010, as compared to the spring, the increase of platelet aggregation and amount has been observed, with the exception of the third trimester, which is marked by the decrease of platelet amount. Hot seasons and liquid intake limitations make additional demands on hemostasis adaptive capacity, increasing the risk of thrombohemorrhagic complications

  7. Thin Film Williamson Nanofluid Flow with Varying Viscosity and Thermal Conductivity on a Time-Dependent Stretching Sheet

    Directory of Open Access Journals (Sweden)

    Waris Khan

    2016-11-01

    Full Text Available This article describes the effect of thermal radiation on the thin film nanofluid flow of a Williamson fluid over an unsteady stretching surface with variable fluid properties. The basic governing equations of continuity, momentum, energy, and concentration are incorporated. The effect of thermal radiation and viscous dissipation terms are included in the energy equation. The energy and concentration fields are also coupled with the effect of Dufour and Soret. The transformations are used to reduce the unsteady equations of velocity, temperature and concentration in the set of nonlinear differential equations and these equations are tackled through the Homotopy Analysis Method (HAM. For the sake of comparison, numerical (ND-Solve Method solutions are also obtained. Special attention has been given to the variable fluid properties’ effects on the flow of a Williamson nanofluid. Finally, the effect of non-dimensional physical parameters like thermal conductivity, Schmidt number, Williamson parameter, Brinkman number, radiation parameter, and Prandtl number has been thoroughly demonstrated and discussed.

  8. Thermal Treatment Temperature and Time Dependence of Contact Angle of Water on Fluorinated Polystyrene as Hydrophobic Film Coating

    Science.gov (United States)

    Tolentino, M. S.; Carpena, J. F.; Javier, R. M.; Aquino, R. R.

    2017-06-01

    The study focuses on the synthesis of fluorinated polystyrene (F-PS) as a hydrophobic film coating and on the investigation of the consequent effects of thermal treatment time and treatment temperature on its contact angle. The fluorinated polystyrene is synthesized via Friedel-Crafts acylation of the benzoic rings by electrophilic substitution of trifluoroacetic anhydride in the presence of AlCl3 in an environment of dichloromethane as the aprotic solvent with a reaction temperature of 36°C. The reaction yielded fluorinated polystyrene characterized by a solid brown substance. FT-IR analysis of the substance had shown band peaks at 1150 cm-1, a wavenumber indicating the presence of fluorine in the synthesized material, which lowers its surface energy. SEM images of the F-PS show nucleation sites giving rise to hierarchical structures on the surface of the material due to the action of fluorination. The contact angle of fluorinated polystyrene, upon application of thermal treatment, increased to as much as 29.26% when compared to the unmodified polystyrene manifesting a preferentially more hydrophobic behavior. It was also found that the contact angle increases linearly with treatment temperature while statistical analysis shows that thermal treatment time has no significant effect on the hydrophobicity of the F- PS.

  9. Performance Limitations in the LHC due to Parasitic Beam-beam Encounters- Parameter Dependence, Scaling, and PACMAN Effects

    CERN Document Server

    Giachino, R; Metral, E; Papotti, G; Pieloni, T; Trad, G; Buffat, X; Kaltchev, D

    2013-01-01

    We studied possible limitations due to the long-range beam-beam effects in the LHC. With a large number of bunches and collisions in all interaction points, we have reduced the crossing angles (separation) to enhance longrange beam-beam effects to evaluate their influence on dynamic aperture and losses. Different β*, number of bunches and intensities have been used in several dedicated experiments and allow the test of the expected scaling laws.

  10. Tuning the Seebeck effect in C60-based hybrid thermoelectric devices through temperature-dependent surface polarization and thermally-modulated interface dipoles.

    Science.gov (United States)

    Liu, Yuchun; Xu, Ling; Zhao, Chen; Shao, Ming; Hu, Bin

    2017-06-07

    Fullerene (C60) is an important n-type organic semiconductor with high electron mobility and low thermal conductivity. In this work, we report the experimental results on the tunable Seebeck effect of C60 hybrid thin-film devices by adopting different oxide layers. After inserting n-type high-dielectric constant titanium oxide (TiOx) and zinc oxide (ZnO) layers, we observed a significantly enhanced n-type Seebeck effect in oxide/C60 hybrid devices with Seebeck coefficients of -5.8 mV K-1 for TiOx/C60 and -2.08 mV K-1 for ZnO/C60 devices at 100 °C, compared with the value of -400 μV K-1 for the pristine C60 device. However, when a p-type nickel oxide (NiO) layer is inserted, the C60 hybrid devices show a p-type to n-type Seebeck effect transition when the temperature increases. The remarkable Seebeck effect and change in Seebeck coefficient in different oxide/C60 hybrid devices can be attributed to two reasons: the temperature-dependent surface polarization difference and thermally-dependent interface dipoles. Firstly, the surface polarization difference due to temperature-dependent electron-phonon coupling can be enhanced by inserting an oxide layer and functions as an additional driving force for the Seebeck effect development. Secondly, thermally-dependent interface dipoles formed at the electrode/oxide interface play an important role in modifying the density of interface states and affecting the charge diffusion in hybrid devices. The surface polarization difference and interface dipoles function in the same direction in hybrid devices with TiOx and ZnO dielectric layers, leading to enhanced n-type Seebeck effect, while the surface polarization difference and interface dipoles generate the opposite impact on electron diffusion in ITO/NiO/C60/Al, leading to a p-type to n-type transition in the Seebeck effect. Therefore, inserting different oxide layers could effectively modulate the Seebeck effect of C60-based hybrid devices through the surface polarization

  11. Radiation-Dependent Limit for the Viability of Bacterial Spores in Halite Fluid Inclusions and on Mars

    Science.gov (United States)

    Kminek, Gerhard; Bada, Jeffrey L.; Pogliano, Kit; Ward, John F.

    2003-01-01

    When claims for the long-term survival of viable organisms are made, either within terrestrial minerals or on Mars, considerations should be made of the limitations imposed by the naturally occurring radiation dose to which they have been exposed. We investigated the effect of ionizing radiation on different bacterial spores by measuring the inactivation constants for B. subtilis and s. marismortui spores in solution as well as for dry spores of B. subtilis and B. thuringiensis. S. marismortui is a halophilic spore that is genetically similar to the recently discovered 2-9-3 bacterium from a halite fluid inclusion, claimed to be 250 million years old, B. thuringiensis is a soil bacterium that is genetically similar to the human pathogens B. anthracis and B. cereus. To relate the inactivation constant to some realistic environments, we calculated the radiation regimen in a halite fluid inclusion and in the Martian subsurface over time. Our conclusion is that the ionizing dose of radiation in those environments limits the survival of viable bacterial spores over long periods. In the absence of an active repair mechanism in the dormant state, the long-term survival of spores is limited to less than 109 million years in halite fluid inclusions, to 100 to 160 million years in the Martian subsurface below 3 m, and to less than 600,000 years in the upper-most meter of Mars.

  12. Generalized Magneto-thermo-microstretch Response of a Half-space with Temperature-dependent Properties During Thermal Shock

    Directory of Open Access Journals (Sweden)

    Qi-lin Xiong

    Full Text Available Abstract The generalized magneto-thermoelastic problem of an infinite homogeneous isotropic microstretch half-space with temperature-dependent material properties placed in a transverse magnetic field is investigated in the context of different generalized thermoelastic theories. The upper surface of the half-space is subjected to a zonal time-dependent heat shock. By solving finite element governing equations, the solution to the problem is obtained, from which the transient magneto-thermoelastic responses, including temperature, stresses, displacements, microstretch, microrotation, induced magnetic field and induced electric field are presented graphically. Comparisons are made in the results obtained under different generalized thermoelastic theories to show some unique features of generalized thermoelasticity, and comparisons are made in the results obtained under three forms of temperature dependent material properties (absolute temperature dependent, reference temperature dependent and temperature-independent to show the effects of absolute temperature and reference temperature. Weibull or Log-normal.

  13. Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH-Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef.

    Science.gov (United States)

    Djimsa, Blanchefort A; Abraham, Anupam; Mafi, Gretchen G; VanOverbeke, Deborah L; Ramanathan, Ranjith

    2017-02-01

    Premature browning is a condition wherein ground beef exhibits a well-done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH-dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in-vitro. Beef patties (lean: fat = 85:15) were packaged in high-oxygen modified atmosphere (HiOX-MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH-dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P dependent reductase, and LDH were different and pH-dependent. LDH was able to generate NADH at 84 °C; whereas NADH-dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color. © 2017 Institute of Food Technologists®.

  14. Improved limits on spin-dependent WIMP-proton interactions from a two liter CF3I bubble chamber.

    Science.gov (United States)

    Behnke, E; Behnke, J; Brice, S J; Broemmelsiek, D; Collar, J I; Cooper, P S; Crisler, M; Dahl, C E; Fustin, D; Hall, J; Hinnefeld, J H; Hu, M; Levine, I; Ramberg, E; Shepherd, T; Sonnenschein, A; Szydagis, M

    2011-01-14

    Data from the operation of a bubble chamber filled with 3.5 kg of CF3I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1  kg  day, consistent with a neutron background. This observation provides strong direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering for WIMP masses >20  GeV/c2.

  15. Efficient local search limitation strategy for single machine total weighted tardiness scheduling with sequence-dependent setup times

    OpenAIRE

    Subramanian, Anand; Farias, Katyanne

    2015-01-01

    This paper concerns the single machine total weighted tardiness scheduling with sequence-dependent setup times, usually referred as $1|s_{ij}|\\sum w_jT_j$. In this $\\mathcal{NP}$-hard problem, each job has an associated processing time, due date and a weight. For each pair of jobs $i$ and $j$, there may be a setup time before starting to process $j$ in case this job is scheduled immediately after $i$. The objective is to determine a schedule that minimizes the total weighted tardiness, where ...

  16. Limitations of serum ferritin to predict liver iron concentration responses to deferasirox therapy in patients with transfusion-dependent thalassaemia.

    Science.gov (United States)

    Porter, John B; Elalfy, Mohsen; Taher, Ali; Aydinok, Yesim; Lee, Szu-Hee; Sutcharitchan, Pranee; El-Ali, Ali; Han, Jackie; El-Beshlawy, Amal

    2017-03-01

    In transfusion-dependent anaemias, while absolute serum ferritin levels broadly correlate with liver iron concentration (LIC), relationships between trends in these variables are unclear. These relationships are important because serum ferritin changes are often used to adjust or switch chelation regimens when liver magnetic resonance imaging (MRI) is unavailable. This post hoc analysis of the EPIC study compared serum ferritin and LIC in 317 patients with transfusion-dependent thalassaemia before and after 1 yr of deferasirox. Serum ferritin responses (decreases) occurred in 73% of patients, 80% of whom also have decreased LIC. However, 52% of patients without a serum ferritin response did decrease LIC and by >1 mg Fe/g dw (median 3.9) in 77% of cases. Absolute serum ferritin and LIC values correlated significantly only when serum ferritin was <4000 ng/mL (r = 0.59; P < 0.0001) and not at higher levels (≥4000 ng/mL; r = 0.19). Serum ferritin response was accompanied by decreased LIC in 89% and 70% of cases when serum ferritin was <4000 or ≥4000 ng/mL, respectively. As serum ferritin non-response was associated with LIC decrease in over half of patients, use of liver MRI may be particularly useful for differentiating true from apparent non-responders to deferasirox based on serum ferritin trends alone. © 2016 The Authors. European Journal of Haematology Published by John Wiley & Sons Ltd.

  17. Replacing effective spectral radiance by temperature in occupational exposure limits to protect against retinal thermal injury from light and near IR radiation.

    Science.gov (United States)

    Madjidi, Faramarz; Behroozy, Ali

    2014-01-01

    Exposure to visible light and near infrared (NIR) radiation in the wavelength region of 380 to 1400 nm may cause thermal retinal injury. In this analysis, the effective spectral radiance of a hot source is replaced by its temperature in the exposure limit values in the region of 380-1400 nm. This article describes the development and implementation of a computer code to predict those temperatures, corresponding to the exposure limits proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). Viewing duration and apparent diameter of the source were inputs for the computer code. At the first stage, an infinite series was created for calculation of spectral radiance by integration with Planck's law. At the second stage for calculation of effective spectral radiance, the initial terms of this infinite series were selected and integration was performed by multiplying these terms by a weighting factor R(λ) in the wavelength region 380-1400 nm. At the third stage, using a computer code, the source temperature that can emit the same effective spectral radiance was found. As a result, based only on measuring the source temperature and accounting for the exposure time and the apparent diameter of the source, it is possible to decide whether the exposure to visible and NIR in any 8-hr workday is permissible. The substitution of source temperature for effective spectral radiance provides a convenient way to evaluate exposure to visible light and NIR.

  18. Limited clinical efficacy of azacitidine in transfusion-dependent, growth factor-resistant, low- and Int-1-risk MDS

    DEFF Research Database (Denmark)

    Holm, Mette; Dybedahl, I; Holm, Mette

    2014-01-01

    This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks...... and a transfusion need of 4 units over 8 weeks were included. Aza 75 mg m(-2) d(-1), 5/28 days, was given for six cycles; non-responding patients received another three cycles combined with Epo 60 000 units per week. Primary end point was transfusion independence (TI). All patients underwent targeted mutational...... screen for 42 candidate genes. Thirty enrolled patients received one cycle of Aza. Ten patients discontinued the study early, 7 due to adverse events including 2 deaths. Thirty-eight serious adverse events were reported, the most common being infection. Five patients achieved TI after six cycles and one...

  19. Temperature-dependent analysis of conduction mechanism of leakage current in thermally grown oxide on 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Sometani, Mitsuru; Takei, Manabu [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, 305-8568 Ibaraki (Japan); Fuji Electric Co. Ltd., 1 Fuji-machi, Hino, 191-8502 Tokyo (Japan); Okamoto, Dai; Harada, Shinsuke; Ishimori, Hitoshi; Takasu, Shinji; Hatakeyama, Tetsuo; Yonezawa, Yoshiyuki; Fukuda, Kenji; Okumura, Hajime [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, 305-8568 Ibaraki (Japan)

    2015-01-14

    The conduction mechanism of the leakage current of a thermally grown oxide on 4H silicon carbide (4H-SiC) was investigated. The dominant carriers of the leakage current were found to be electrons by the carrier-separation current-voltage method. The current-voltage and capacitance-voltage characteristics, which were measured over a wide temperature range, revealed that the leakage current in SiO{sub 2}/4H-SiC on the Si-face can be explained as the sum of the Fowler-Nordheim (FN) tunneling and Poole-Frenkel (PF) emission leakage currents. A rigorous FN analysis provided the true barrier height for the SiO{sub 2}/4H-SiC interface. On the basis of Arrhenius plots of the PF current separated from the total leakage current, the existence of carbon-related defects and/or oxygen vacancy defects was suggested in thermally grown SiO{sub 2} films on the Si-face of 4H-SiC.

  20. Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

    Energy Technology Data Exchange (ETDEWEB)

    Atitoaie, Alexandru [Department of Physics and CARPATH, ' ' Alexandru Ioan Cuza' ' University of Iasi, Boulevard Carol I, no. 11, Iasi 700506 (Romania); Tanasa, Radu, E-mail: radu.tanasa@uaic.ro [Department of Physics and CARPATH, ' ' Alexandru Ioan Cuza' ' University of Iasi, Boulevard Carol I, no. 11, Iasi 700506 (Romania); Enachescu, Cristian, E-mail: cristian.enachescu@uaic.ro [Department of Physics and CARPATH, ' ' Alexandru Ioan Cuza' ' University of Iasi, Boulevard Carol I, no. 11, Iasi 700506 (Romania)

    2012-04-15

    Spin crossover compounds are photo-magnetic bistable molecular magnets with two states in thermodynamic competition: the diamagnetic low-spin state and paramagnetic high-spin state. The thermal transition between the two states is often accompanied by a wide hysteresis, premise for possible application of these materials as recording media. In this paper we study the influence of the system's size on the thermal hysteresis loops using Monte Carlo simulations based on an Arrhenius dynamics applied for an Ising like model with long- and short-range interactions. We show that using appropriate boundary conditions it is possible to reproduce both the drop of hysteresis width with decreasing particle size, the hysteresis shift towards lower temperatures and the incomplete transition, as in the available experimental data. The case of larger systems composed by several sublattices is equally treated reproducing the shrinkage of the hysteresis loop's width experimentally observed. - Highlights: Black-Right-Pointing-Pointer A study concerning size effects in spin crossover nanoparticles hysteresis is presented. Black-Right-Pointing-Pointer An Ising like model with short- and long-range interactions and Arrhenius dynamics is employed. Black-Right-Pointing-Pointer In open boundary system the hysteresis width decreases with particle size. Black-Right-Pointing-Pointer With appropriate environment, hysteresis loop is shifted towards lower temperature and transition is incomplete.

  1. Ultrafast demagnetization, spin-dependent Seebeck effect, and thermal spin transfer torque in Pt/TbFe/Cu and Pt/TbFe/Cu/Fe thin films

    Science.gov (United States)

    Kimling, Johannes; Hebler, Birgit; Kimling, Judith; Albrecht, Manfred; Cahill, David G.

    We investigate diffusive spin currents in Pt(20nm)/TbFe(10nm)/Cu(100nm) and Pt(20 nm)/TbFe(10nm)/ Cu(100nm)/Fe(3nm) stacks using time-resolved magneto-optic Kerr effect (TRMOKE) and time-domain thermoreflectance measurements. Our experiments are based on two hypothesis: (1) fast changes of magnetization due to laser excitation are transferred into spin accumulation, e.g., via electron-magnon scattering; the generated spin accumulation drives a diffusive spin current into adjacent normal metal layers; (2) electronic thermal transport through the ferromagnetic layer injects a spin current into adjacent normal metal layers, based on the spin-dependent Seebeck effect. We excite the Pt layer with ps-laser pulses. Resulting diffusive spin currents generate nonequilibrium magnetization in the Cu layer (sample I) and induce a precession of the magnetization of the Fe layer via spin transfer torque (sample II). Both responses are probed using TRMOKE. Prior experiments used [Co(0.2nm)/Pt(0.4nm)]x5/Co(0.2nm) instead of TbFe. The ferrimagnetic TbFe layer with introduces two major modifications: (1) slow demagnetization behavior, and (2) large thermal resistance. Hence, thermal spin transfer torques can be observed on significantly longer time scales. Financial support by the German Research Foundation under DFG-Grant No. KI 1893/1-1 and DFG-Grant No. AL 618/21-1 are kindly acknowledged.

  2. Response of heat shock protein genes of the oriental fruit moth under diapause and thermal stress reveals multiple patterns dependent on the nature of stress exposure.

    Science.gov (United States)

    Zhang, Bo; Peng, Yu; Zheng, Jincheng; Liang, Lina; Hoffmann, Ary A; Ma, Chun-Sen

    2016-07-01

    Heat shock protein gene (Hsp) families are thought to be important in thermal adaptation, but their expression patterns under various thermal stresses have still been poorly characterized outside of model systems. We have therefore characterized Hsp genes and their stress responses in the oriental fruit moth (OFM), Grapholita molesta, a widespread global orchard pest, and compared patterns of expression in this species to that of other insects. Genes from four Hsp families showed variable expression levels among tissues and developmental stages. Members of the Hsp40, 70, and 90 families were highly expressed under short exposures to heat and cold. Expression of Hsp40, 70, and Hsc70 family members increased in OFM undergoing diapause, while Hsp90 was downregulated. We found that there was strong sequence conservation of members of large Hsp families (Hsp40, Hsp60, Hsp70, Hsc70) across taxa, but this was not always matched by conservation of expression patterns. When the large Hsps as well as small Hsps from OFM were compared under acute and ramping heat stress, two groups of sHsps expression patterns were apparent, depending on whether expression increased or decreased immediately after stress exposure. These results highlight potential differences in conservation of function as opposed to sequence in this gene family and also point to Hsp genes potentially useful as bioindicators of diapause and thermal stress in OFM.

  3. The lesser known challenge of climate change: thermal variance and sex-reversal in vertebrates with temperature-dependent sex determination.

    Directory of Open Access Journals (Sweden)

    Jennifer L Neuwald

    Full Text Available Climate change is expected to disrupt biological systems. Particularly susceptible are species with temperature-dependent sex determination (TSD, as in many reptiles. While the potentially devastating effect of rising mean temperatures on sex ratios in TSD species is appreciated, the consequences of increased thermal variance predicted to accompany climate change remain obscure. Surprisingly, no study has tested if the effect of thermal variance around high-temperatures (which are particularly relevant given climate change predictions has the same or opposite effects as around lower temperatures. Here we show that sex ratios of the painted turtle (Chrysemys picta were reversed as fluctuations increased around low and high unisexual mean-temperatures. Unexpectedly, the developmental and sexual responses around female-producing temperatures were decoupled in a more complex manner than around male-producing values. Our novel observations are not fully explained by existing ecological models of development and sex determination, and provide strong evidence that thermal fluctuations are critical for shaping the biological outcomes of climate change.

  4. Thermal survival limits of young and mature larvae of a cold stenothermal chironomid from the Alps (Diamesinae: Pseudodiamesa branickii [Nowicki, 1873]).

    Science.gov (United States)

    Lencioni, Valeria; Bernabò, Paola

    2017-04-01

    The threats posed by climate change make it important to expand knowledge concerning cold and heat tolerance in stenothermal species from habitats potentially threatened by temperature changes. Thermal limits and basal metabolism variations were investigated in Pseudodiamesa branickii (Diptera: Chironomidae) under thermal stress between -20 and 37 °C. Supercooling point (SCP), lower (LLTs) and upper lethal temperatures (ULTs), and oxygen consumption rate were measured in overwintering young (1st and 2nd instar) and mature (3rd and 4th instar) larvae from an Alpine glacier-fed stream. Both young and mature larvae were freezing tolerant (SCPs = -7.1 °C and -6.4 °C, respectively; LLT100 -20 °C) and thermotolerant (ULT50 = 31.7 ± 0.4, 32.5 ± 0.3, respectively). However, ontogenetic differences in acute tolerance were observed. The LLT50 calculated for the young larvae (= -7.4 °C) was almost equal to their SCP (= -7.1 °C) and the overlapping of the proportion of mortality curve with the CPIF curve highlighted that the young larvae are borderline between freezing tolerance and freezing avoidance. Furthermore, a lower ULT100 in the young larvae (of ca. 1 °C), suggests that they are less thermotolerant than mature larvae. Finally, young larvae exhibit a higher oxygen consumption rate (mgO2 /gAFDM/h) at any temperature tested and are overall less resistant to oxygen depletion compared to mature larvae at ≥10 °C. These findings suggest that mature larvae enter into a dormant state by lowering their basal metabolism until environmental conditions improve in order to save energy for life cycle completion during stressful conditions. © 2015 Institute of Zoology, Chinese Academy of Sciences.

  5. Rapid thermal annealing and modulation-doping effects on InAs/GaAs quantum dots photoluminescence dependence on excitation power

    Energy Technology Data Exchange (ETDEWEB)

    Chaâbani, W. [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Melliti, A., E-mail: adnenmelliti@yahoo.fr [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Maaref, M.A. [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Testelin, C. [Institut des NanoSciences de Paris, UPMC Univ., Paris 06, UMR 7588, F-75005 Paris (France); CNRS, UMR 7588, INSP, F-75005 Paris (France); Lemaître, A. [Laboratoire de Photonique et Nanostructures (LPN), CNRS, Route de Nozay, F-91460 Marcoussis (France)

    2016-07-15

    The optical properties of p-doped and annealed InAs/GaAs quantum dots (QDs) was investigated by photoluminescence (PL) as a function of temperature and excitation power density (P{sub exc}). At low-T, PL spectra of rapid thermal annealing (RTA) and p-modulation doped QDs show an energy blueshift and redshift, respectively. A superlinear dependence of integrated PL intensity on P{sub exc} at high-T was found only for undoped QD. The superlinearity was suppressed by modulation-doping and RTA effects. A linear dependence of I{sub PL} at all temperatures and a decrease of the carrier-carrier Coulomb interaction at high-T was found after RTA.

  6. The upper reference limit for thyroid peroxidase autoantibodies is method-dependent: A collaborative study with biomedical industries.

    Science.gov (United States)

    Tozzoli, Renato; D'Aurizio, Federica; Ferrari, Anna; Castello, Roberto; Metus, Paolo; Caruso, Beatrice; Perosa, Anna Rosa; Sirianni, Francesca; Stenner, Elisabetta; Steffan, Agostino; Villalta, Danilo

    2016-01-15

    The determination of the upper reference limit (URL) for thyroid peroxidase autoantibodies (TPOAbs) is a contentious issue, because of the difficulty in defining the reference population. The aim of this study was to establish the URL (eURL) for TPOAbs, according to the National Academy of Clinical Biochemistry (NACB) guidelines and to compare them with those obtained in a female counterpart, by the use of six commercial automated platforms. 120 healthy males and 120 healthy females with NACB-required characteristics (Unicel DxI (UNI) and Lumipulse G1200, Fujirebio. Within each method, TPOAbs values had a high degree of dispersion and the eURLs were lower than those stated by the manufacturer. A statistically significant difference (p0.05). Despite the analytical harmonization, the wide dispersion of the results and the differences of the eURLs between methods suggest the need of further studies focusing on TPO antigen preparations as the possible source of variability between different assays. In addition, the lack of clinical significant difference between males and females, in terms of TPOAb eURLs, confirms the suitability of the NACB recommendations. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Concentration-dependent ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline scandia-stabilized zirconia

    DEFF Research Database (Denmark)

    Sillassen, M.; Eklund, P.; Pryds, Nini

    2010-01-01

    grain size, yielding a grain size of 6 nm and a microstrain of 2.5% at -200 V and -250 V with additional incorporation of argon. Temperature-dependent impedance spectroscopy of the SSZ films showed that the in-plane ionic conductivity had a maximum close to 10.7 mol% and decreased almost an order...... of magnitude as the scandia - content was increased to 15.9 mol%. The activation energy for oxygen ion migration was determined to be between 1.30 - 1.43 eV. In addition, no dependence on grain size was observed. The above observations suggest a bulk mechanism for ionic conduction....

  8. Amplitude Dependent Internal Friction in a Mg-Al-Zn Alloy Studied after Thermal and Mechanical Treatment

    Directory of Open Access Journals (Sweden)

    Zuzanka Trojanová

    2017-10-01

    Full Text Available The amplitude-dependent internal friction of continuously-cast and rolled AZ31 magnesium alloy was measured in this study. Samples were annealed and quenched step by step; immediately after the treatment, the amplitude dependence of the logarithmic decrement was measured. Changes in the microstructure due to thermomechanical treatment were reflected in changes in the damping. Internal friction is influenced by the dislocation substructure and its modification due to solute atoms migration, microplastic deformation, and twins’ formation. Internal friction in the rolled sheets is affected by the rolling texture.

  9. Internal photoemission for photovoltaic using p-type Schottky barrier: Band structure dependence and theoretical efficiency limits

    Science.gov (United States)

    Shih, Ko-Han; Chang, Yin-Jung

    2018-01-01

    Solar energy conversion via internal photoemission (IPE) across a planar p-type Schottky junction is quantified for aluminum (Al) and copper (Cu) in the framework of direct transitions with non-constant matrix elements. Transition probabilities and k-resolved group velocities are obtained based on pseudo-wavefunction expansions and realistic band structures using the pseudopotential method. The k-resolved number of direct transitions, hole photocurrent density, quantum yield (QY), and the power conversion efficiency (PCE) under AM1.5G solar irradiance are subsequently calculated and analyzed. For Al, the parabolic and "parallel-band" effect along the U-W-K path significantly enhances the transition rate with final energies of holes mainly within 1.41 eV below the Fermi energy. For Cu, d-state hot holes mostly generated near the upper edge of 3d bands dominate the hole photocurrent and are weekly (strongly) dependent on the barrier height (metal film thickness). Hot holes produced in the 4s band behave just oppositely to their d-state counterparts. Non-constant matrix elements are shown to be necessary for calculations of transitions due to time-harmonic perturbation in Cu. Compared with Cu, Al-based IPE in p-type Schottky shows the highest PCE (QY) up to about 0.2673% (5.2410%) at ΦB = 0.95 eV (0.5 eV) and a film thickness of 11 nm (20 nm). It is predicted that metals with relatively dispersionless d bands (such as Cu) in most cases do not outperform metals with photon-accessible parallel bands (such as Al) in photon energy conversion using a planar p-type Schottky junction.

  10. Limitation of Infarct Size and No-Reflow by Intracoronary Adenosine Depends Critically on Dose and Duration.

    Science.gov (United States)

    Yetgin, Tuncay; Uitterdijk, André; Te Lintel Hekkert, Maaike; Merkus, Daphne; Krabbendam-Peters, Ilona; van Beusekom, Heleen M M; Falotico, Robert; Serruys, Patrick W; Manintveld, Olivier C; van Geuns, Robert-Jan M; Zijlstra, Felix; Duncker, Dirk J

    2015-12-28

    In the absence of effective clinical pharmacotherapy for prevention of reperfusion-mediated injury, this study re-evaluated the effects of intracoronary adenosine on infarct size and no-reflow in a porcine model of acute myocardial infarction using clinical bolus and experimental high-dose infusion regimens. Despite the clear cardioprotective effects of adenosine, when administered prior to ischemia, studies on cardioprotection by adenosine when administered at reperfusion have yielded contradictory results in both pre-clinical and clinical settings. Swine (54 ± 1 kg) were subjected to a 45-min mid-left anterior descending artery occlusion followed by 2 h of reperfusion. In protocol A, an intracoronary bolus of 3 mg adenosine injected over 1 min (n = 5) or saline (n = 10) was administered at reperfusion. In protocol B, an intracoronary infusion of 50 μg/kg/min adenosine (n = 15) or saline (n = 21) was administered starting 5 min prior to reperfusion and continued throughout the 2-h reperfusion period. In protocol A, area-at-risk, infarct size, and no-reflow were similar between groups. In protocol B, risk zones were similar, but administration of adenosine resulted in significant reductions in infarct size from 59 ± 3% of the area-at-risk in control swine to 46 ± 4% (p = 0.02), and no-reflow from 49 ± 6% of the infarct area to 26 ± 6% (p = 0.03). During reperfusion, intracoronary adenosine can limit infarct size and no-reflow in a porcine model of acute myocardial infarction. However, protection was only observed when adenosine was administered via prolonged high-dose infusion, and not via short-acting bolus injection. These findings warrant reconsideration of adenosine as an adjuvant therapy during early reperfusion. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  11. [Rectal temperature-time of death nomogram: dependence of corrective factors of body weight in significant thermal insulating conditions].

    Science.gov (United States)

    Henssge, C

    1992-01-01

    98 test coolings were made under various cooling conditions (moving air, two types of both clothing and covering) on dummies of real masses of 1, 3.3, 9.9, 24.5 and 33.4 kg resp. which cool under standard conditions (unclothed, uncovered, still air) like human bodies of 14, 33, 41, 83 and 104 kg resp. The results provide evidence on a nonlinear dependence of corrective factors of body weight upon the body weight. The dynamics of the dependence increases with the thickness of thermic isolation. Transferred to the use of the nomogram method on bodies, cooling conditions requiring corrective factors known by experience between 0.75 (moving air) and 1.3 (rather thin clothing/covering) can be used as in the past independent on the body weight. Only in higher corrective factors for thicker clothing/covering according to experience the dependence of corrective factors on the body weight must be taken into account in bodies of a very high or low body weight. Beside a simplified table a formula for computing is also given for that purpose.

  12. The Limited Role of Number of Nested Syntactic Dependencies in Accounting for Processing Cost: Evidence from German Simplex and Complex Verbal Clusters

    Directory of Open Access Journals (Sweden)

    Markus Bader

    2018-01-01

    Full Text Available This paper presents three acceptability experiments investigating German verb-final clauses in order to explore possible sources of sentence complexity during human parsing. The point of departure was De Vries et al.'s (2011 generalization that sentences with three or more crossed or nested dependencies are too complex for being processed by the human parsing mechanism without difficulties. This generalization is partially based on findings from Bach et al. (1986 concerning the acceptability of complex verb clusters in German and Dutch. The first experiment tests this generalization by comparing two sentence types: (i sentences with three nested dependencies within a single clause that contains three verbs in a complex verb cluster; (ii sentences with four nested dependencies distributed across two embedded clauses, one center-embedded within the other, each containing a two-verb cluster. The results show that sentences with four nested dependencies are judged as acceptable as control sentences with only two nested dependencies, whereas sentences with three nested dependencies are judged as only marginally acceptable. This argues against De Vries et al.'s (2011 claim that the human parser can process no more than two nested dependencies. The results are used to refine the Verb-Cluster Complexity Hypothesis of Bader and Schmid (2009a. The second and the third experiment investigate sentences with four nested dependencies in more detail in order to explore alternative sources of sentence complexity: the number of predicted heads to be held in working memory (storage cost in terms of the Dependency Locality Theory [DLT], Gibson, 2000 and the length of the involved dependencies (integration cost in terms of the DLT. Experiment 2 investigates sentences for which storage cost and integration cost make conflicting predictions. The results show that storage cost outweighs integration cost. Experiment 3 shows that increasing integration cost in sentences

  13. Dependence of N incorporation into (Ga)InAsN QDs on Ga content probed by rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Gargallo-Caballero, R.; Guzman, A.; Ulloa, J.M.; Hierro, A.; Calleja, E. [Instituto de Sistemas Optoelectronicos y Microtecnologia (ISOM) - Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid (Spain); Hopkinson, M. [Department of Electronic and Electrical Engineering, EPSRC National Centre for III-V Technologies, University of Sheffield (United Kingdom)

    2009-06-15

    In this letter we demonstrate that the N incorporation into (Ga)InAsN quantum dots (QDs), grown on GaAs (100) by radio-frequency (RF) plasma assisted molecular beam epitaxy (MBE), is enhanced as the Ga content increases up to 30% and decreases for Ga contents higher than 30%. Thus, this effect exhibits a maximum N incorporation with a Ga content of 30%. Two sets of (Ga)InAsN QDs samples have been grown under the same growth conditions but with different N contents in one of them and with different Ga concentration in the other set. Optical analysis using Photoluminescence (PL) measurements of the as-grown and post growth rapid thermal annealed samples have been performed. The experimental results show a clear increase of the blueshift with the N concentration as occurred in dilute nitride quantum well (QW) structures. PL peak emission wavelength as high as 1.55{mu}m has been obtained from QDs capped with GaAs. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Analytical solution to convection-radiation of a continuously moving fin with temperature-dependent thermal conductivity

    Directory of Open Access Journals (Sweden)

    Moradi Amir

    2013-01-01

    Full Text Available In this article, the simultaneous convection-radiation heat transfer of a moving fin of variable thermal conductivity is studied. The differential transformation method (DTM is applied for an analytic solution for heat transfer in fin with two different profiles. Fin profiles are rectangular and exponential. The accuracy of analytic solution is validated by comparing it with the numerical solution that is obtained by fourth-order Runge-Kutta method. The analytical and numerical results are shown for different values of the embedding parameters. DTM results show that series converge rapidly with high accuracy. The results indicate that the fin tip temperature increases when ambient temperature increases. Conversely, the fin tip temperature decreases with an increase in the Peclet number, convection-conduction and radiation-conduction parameters. It is shown that the fin tip temperature of the exponential profile is higher than the rectangular one. The results indicate that the numerical data and analytical method are in a good agreement with each other.

  15. The Urban Heat Island and its spatial scale dependent impact on survival and development in butterflies of different thermal sensitivity.

    Science.gov (United States)

    Kaiser, Aurélien; Merckx, Thomas; Van Dyck, Hans

    2016-06-01

    Climate alteration is one of the most cited ecological consequences of urbanization. However, the magnitude of this impact is likely to vary with spatial scale. We investigated how this alteration affects the biological fitness of insects, which are especially sensitive to ambient conditions and well-suited organisms to study urbanization-related changes in phenotypic traits. We monitored temperature and relative air humidity in wooded sites characterized by different levels of urbanization in the surroundings. Using a split-brood design experiment, we investigated the effect of urbanization at the local (i.e., 200 × 200 m) and landscape (i.e., 3 × 3 km) scale on two key traits of biological fitness in two closely related butterfly species that differ in thermal sensitivity. In line with the Urban Heat Island concept, urbanization led to a 1°C increase in daytime temperature and an 8% decrease in daytime relative humidity at the local scale. The thermophilous species Lasiommata megera responded at the local scale: larval survival increased twofold in urban compared to rural sites. Urbanized sites tended to produce bigger adults, although this was the case for males only. In the woodland species Pararge aegeria, which has recently expanded its ecological niche, we did not observe such a response, neither at the local, nor at the landscape scale. These results demonstrate interspecific differences in urbanization-related phenotypic plasticity and larval survival. We discuss larval pre-adaptations in species of different ecological profiles to urban conditions. Our results also highlight the significance of considering fine-grained spatial scales in urban ecology.

  16. Temperature-dependent vibration analysis of a FG viscoelastic cylindrical microshell under various thermal distribution via modified length scale parameter: a numerical solution

    Science.gov (United States)

    Safarpour, Hamed; Mohammadi, Kianoosh; Ghadiri, Majid

    2017-04-01

    In this article, the vibrational analysis of temperature-dependent cylindrical functionally graded (FG) microshells surrounded by viscoelastic a foundation is investigated by means of the modified couple stress theory (MCST). MCST is applied to this model to be productive in design and analysis of micro actuators and micro sensors. The modeled cylindrical FG microshell, its equations of motion and boundary conditions are derived by Hamilton's principle and the first-order shear deformation theory (FSDT). For the first time, in the present study, functionally graded length scale parameter which changes along the thickness has been considered in the temperature-dependent cylindrical FG microshell. The accuracy of the present model is verified with previous studies and also with those obtained by analytical Navier method. The novelty of the current study is consideration of viscoelastic foundation, various thermal loadings and size effect as well as satisfying various boundary conditions implemented on the temperature-dependent cylindrical FG microshell using MCST. Generalized differential quadrature method (GDQM) is applied to discretize the equations of motion. Then, some factors are investigated such as the influence of length to radius ratio, damping, Winkler and Pasternak foundations, different temperature changes, circumferential wave numbers, and boundary conditions on natural frequency of the cylindrical FG microshell. The results have many applications such as modeling of microrobots and biomedical microsystems.

  17. Numerical investigation of magnetohydrodynamic slip flow of power-law nanofluid with temperature dependent viscosity and thermal conductivity over a permeable surface

    Directory of Open Access Journals (Sweden)

    Hussain Sajid

    2017-12-01

    Full Text Available In this paper, a numerical investigation is carried out to study the effect of temperature dependent viscosity and thermal conductivity on heat transfer and slip flow of electrically conducting non-Newtonian nanofluids. The power-law model is considered for water based nanofluids and a magnetic field is applied in the transverse direction to the flow. The governing partial differential equations(PDEs along with the slip boundary conditions are transformed into ordinary differential equations(ODEs using a similarity technique. The resulting ODEs are numerically solved by using fourth order Runge-Kutta and shooting methods. Numerical computations for the velocity and temperature profiles, the skin friction coefficient and the Nusselt number are presented in the form of graphs and tables. The velocity gradient at the boundary is highest for pseudoplastic fluids followed by Newtonian and then dilatant fluids. Increasing the viscosity of the nanofluid and the volume of nanoparticles reduces the rate of heat transfer and enhances the thickness of the momentum boundary layer. The increase in strength of the applied transverse magnetic field and suction velocity increases fluid motion and decreases the temperature distribution within the boundary layer. Increase in the slip velocity enhances the rate of heat transfer whereas thermal slip reduces the rate of heat transfer.

  18. Numerical investigation of magnetohydrodynamic slip flow of power-law nanofluid with temperature dependent viscosity and thermal conductivity over a permeable surface

    Science.gov (United States)

    Hussain, Sajid; Aziz, Asim; Khalique, Chaudhry Masood; Aziz, Taha

    2017-12-01

    In this paper, a numerical investigation is carried out to study the effect of temperature dependent viscosity and thermal conductivity on heat transfer and slip flow of electrically conducting non-Newtonian nanofluids. The power-law model is considered for water based nanofluids and a magnetic field is applied in the transverse direction to the flow. The governing partial differential equations(PDEs) along with the slip boundary conditions are transformed into ordinary differential equations(ODEs) using a similarity technique. The resulting ODEs are numerically solved by using fourth order Runge-Kutta and shooting methods. Numerical computations for the velocity and temperature profiles, the skin friction coefficient and the Nusselt number are presented in the form of graphs and tables. The velocity gradient at the boundary is highest for pseudoplastic fluids followed by Newtonian and then dilatant fluids. Increasing the viscosity of the nanofluid and the volume of nanoparticles reduces the rate of heat transfer and enhances the thickness of the momentum boundary layer. The increase in strength of the applied transverse magnetic field and suction velocity increases fluid motion and decreases the temperature distribution within the boundary layer. Increase in the slip velocity enhances the rate of heat transfer whereas thermal slip reduces the rate of heat transfer.

  19. Effect of Size-Dependent Thermal Instability on Synthesis of Zn2 SiO4-SiOx Core–Shell Nanotube Arrays and Their Cathodoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Dierre Benjamin

    2010-01-01

    Full Text Available Abstract Vertically aligned Zn2SiO4-SiOx(x < 2 core–shell nanotube arrays consisting of Zn2SiO4-nanoparticle chains encapsulated into SiOx nanotubes and SiOx-coated Zn2SiO4 coaxial nanotubes were synthesized via one-step thermal annealing process using ZnO nanowire (ZNW arrays as templates. The appearance of different nanotube morphologies was due to size-dependent thermal instability and specific melting of ZNWs. With an increase in ZNW diameter, the formation mechanism changed from decomposition of “etching” to Rayleigh instability and then to Kirkendall effect, consequently resulting in polycrystalline Zn2SiO4-SiOx coaxial nanotubes, single-crystalline Zn2SiO4-nanoparticle-chain-embedded SiOx nanotubes, and single-crystalline Zn2SiO4-SiOx coaxial nanotubes. The difference in spatially resolved optical properties related to a particular morphology was efficiently documented by means of cathodoluminescence (CL spectroscopy using a middle-ultraviolet emission at 310 nm from the Zn2SiO4 phase.

  20. Origins of Negative Strain Rate Dependence of Stress Corrosion Cracking Initiation in Alloy 690, and Intergranular Crack Formation in Thermally Treated Alloy 690

    Science.gov (United States)

    Kim, Young Suk; Kim, Sung Soo

    2016-09-01

    We show that enhanced stress corrosion cracking (SCC) initiation in cold-rolled Alloy 690 with decreasing strain rate is related to the rate of short-range ordering (SRO) but not to the time-dependent corrosion process. Evidence for SRO is provided by aging tests on cold-rolled Alloy 690 at 623 K and 693 K (350 °C and 420 °C), respectively, which demonstrate its enhanced lattice contraction and hardness increase with aging temperature and time, respectively. Secondary intergranular cracks formed only in thermally treated and cold-rolled Alloy 690 during SCC tests, which are not SCC cracks, are caused by its lattice contraction by SRO before SCC tests but not by the orientation effect.

  1. Combined effects of chemical reaction and temperature dependent heat source on MHD mixed convective flow of a couple-stress fluid in a vertical wavy porous space with travelling thermal waves

    Directory of Open Access Journals (Sweden)

    Muthuraj R.

    2012-01-01

    Full Text Available A mathematical model is developed to examine the effect of chemical reaction on MHD mixed convective heat and mass transfer flow of a couple-stress fluid in vertical porous space in the presence of temperature dependent heat source with travelling thermal waves. The dimensionless governing equations are assumed to be made up of two parts: a mean part corresponding to the fully developed mean flow, and a small perturbed part, using amplitude as a small parameter. The analytical solution of perturbed part have been carried out by using the long-wave approximation. The expressions for the zeroth-order and the first order solutions are obtained and the results of the heat and mass transfer characteristics are presented graphically for various values of parameters entering into the problem. It is noted that velocity of the fluid increases with the increase of the couple stress parameter and increasing the chemical reaction parameter leads suppress the velocity of the fluid. Cross velocity decreases with an increase of the phase angle. The increase of the chemical reaction parameter and Schmidt number lead to decrease the fluid concentration. The hydrodynamic case for a non-porous space in the absence of the temperature dependent heat source for Newtonian fluid can be captured as a limiting case of our analysis by taking, and α1→0, Da→∞, a→∞.

  2. Partitioning the metabolic scope: the importance of anaerobic metabolism and implications for the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis

    Science.gov (United States)

    Ejbye-Ernst, Rasmus; Michaelsen, Thomas Y.; Tirsgaard, Bjørn; Wilson, Jonathan M.; Jensen, Lasse F.; Steffensen, John F.; Pertoldi, Cino; Aarestrup, Kim; Svendsen, Jon C.

    2016-01-01

    Ongoing climate change is predicted to affect the distribution and abundance of aquatic ectotherms owing to increasing constraints on organismal physiology, in particular involving the metabolic scope (MS) available for performance and fitness. The oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis prescribes MS as an overarching benchmark for fitness-related performance and assumes that any anaerobic contribution within the MS is insignificant. The MS is typically derived from respirometry by subtracting standard metabolic rate from the maximal metabolic rate; however, the methodology rarely accounts for anaerobic metabolism within the MS. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), this study tested for trade-offs (i) between aerobic and anaerobic components of locomotor performance; and (ii) between the corresponding components of the MS. Data collection involved measuring oxygen consumption rate at increasing swimming speeds, using the gait transition from steady to unsteady (burst-assisted) swimming to detect the onset of anaerobic metabolism. Results provided evidence of the locomotor performance trade-off, but only in S. aurata. In contrast, both species revealed significant negative correlations between aerobic and anaerobic components of the MS, indicating a trade-off where both components of the MS cannot be optimized simultaneously. Importantly, the fraction of the MS influenced by anaerobic metabolism was on average 24.3 and 26.1% in S. aurata and P. reticulata, respectively. These data highlight the importance of taking anaerobic metabolism into account when assessing effects of environmental variation on the MS, because the fraction where anaerobic metabolism occurs is a poor indicator of sustainable aerobic performance. Our results suggest that without accounting for anaerobic metabolism within the MS, studies involving the OCLTT hypothesis could overestimate the metabolic scope available for

  3. TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription.

    Science.gov (United States)

    Okuda, Hiroshi; Takahashi, Satoshi; Takaori-Kondo, Akifumi; Yokoyama, Akihiko

    2016-10-17

    Gene rearrangement of the mixed lineage leukemia (MLL) gene causes leukemia by inducing the constitutive expression of a gene subset normally expressed only in the immature haematopoietic progenitor cells. MLL gene rearrangements often generate fusion products of MLL and a component of the AF4 family/ENL family/P-TEFb (AEP) complex. MLL-AEP fusion proteins have the potential of constitutively recruiting the P-TEFb elongation complex. Thus, it is hypothesized that relieving the promoter proximal pausing of RNA polymerase II is the rate-limiting step of MLL fusion-dependent transcription. AEP also has the potential to recruit the mediator complex via MED26. We recently showed that AEP activates transcription initiation by facilitating TBP loading to the TATA element through the SL1 complex. In the present study, we show that the key activity responsible for the oncogenic property of MLL-AEP fusion proteins is the TBP loading activity, and not the mediator recruitment or transcriptional elongation activities. Thus, we propose that TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription.

  4. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm.

    Science.gov (United States)

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-05-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t (0.66) [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards.

  5. Limits on the spin-dependent WIMP-nucleon cross sections from the first science run of the ZEPLIN-III experiment.

    Science.gov (United States)

    Lebedenko, V N; Araújo, H M; Barnes, E J; Bewick, A; Cashmore, R; Chepel, V; Currie, A; Davidge, D; Dawson, J; Durkin, T; Edwards, B; Ghag, C; Horn, M; Howard, A S; Hughes, A J; Jones, W G; Joshi, M; Kalmus, G E; Kovalenko, A G; Lindote, A; Liubarsky, I; Lopes, M I; Lüscher, R; Lyons, K; Majewski, P; Murphy, A St J; Neves, F; da Cunha, J Pinto; Preece, R; Quenby, J J; Scovell, P R; Silva, C; Solovov, V N; Smith, N J T; Smith, P F; Stekhanov, V N; Sumner, T J; Thorne, C; Walker, R J

    2009-10-09

    We present new experimental constraints on the WIMP-nucleon spin-dependent elastic cross sections using data from the first science run of ZEPLIN-III, a two-phase xenon experiment searching for galactic dark matter weakly interacting massive particles based at the Boulby mine. Analysis of approximately 450 kg x days fiducial exposure allow us to place a 90%-confidence upper limit on the pure WIMP-neutron cross section of sigma(n)=1.9x10(-2) pb at 55 GeV/c(2) WIMP mass. Recent calculations of the nuclear spin structure based on the Bonn charge-dependent nucleon-nucleon potential were used for the odd-neutron isotopes 129Xe and 131Xe. These indicate that the sensitivity of xenon targets to the spin-dependent WIMP-proton interaction could be much lower than implied by previous calculations, whereas the WIMP-neutron sensitivity is impaired only by a factor of approximately 2.

  6. Towards a postponement of activities of daily living dependence and mobility limitations: Trends in healthy life years in old age in Sweden.

    Science.gov (United States)

    Lagergren, Mårten; Johnell, Kristina; Schön, Pär; Danielsson, Maria

    2017-07-01

    To investigate the development of healthy life expectancy from 65 years (HLE65) in Sweden in the period 1980-2011 using the health indicators activities of daily living (ADL) and mobility limitations within the framework of the postponement, compression and expansion theories. Sources of data for the HLE computations were Swedish national mortality statistics and the nationwide Swedish Surveys of Living Conditions, conducted biennially by Statistics Sweden since 1974. We used the Sullivan method for calculations of HLE and a decomposition into mortality and disability effects was made. Life expectancy at age 65 (LE65) increased by 3.1 years for women and 4.0 years for men from 1980-1985 to 2006-2011. HLE65 calculated according to ADL and mobility limitations increased more rapidly than LE65 for both men and women ( ppostponement hypothesis and there is also a tendency for compression. Thus the years with ADL dependence and mobility limitations are postponed to a higher age and the numbers of these years have decreased.

  7. Factors Affecting the Thickness of Thermal Aureoles

    Directory of Open Access Journals (Sweden)

    Catherine Annen

    2017-10-01

    Full Text Available Intrusions of magma induce thermal aureoles in the country rock. Analytical solutions predict that the thickness of an aureole is proportional to the thickness of the intrusion. However, in the field, thermal aureoles are often significantly thinner or wider than predicted by simple thermal models. Numerical models show that thermal aureoles are wider if the heat transfer in the magma is faster than in the country rock due to contrasts in thermal diffusivities or the effect of magma convection. Large thermal aureoles can also be caused by repeated injection close to the contact. Aureoles are thin when heat transfer in the country rock is faster than heat transfer within the magma or in case of incrementally, slowly emplaced magma. Absorption of latent heat due to metamorphic reactions or water volatilization also affects thermal aureoles but to a lesser extent. The way these parameters affect the thickness of a thermal aureole depends on the isotherm under consideration, hence on which metamorphic phase is used to draw the limit of the aureole. Thermal aureoles provide insight on the dynamics of intrusions emplacement. Although available examples are limited, asymmetric aureoles point to magma emplacement by over-accretion for mafic cases and by under-accretion for felsic cases, consistent with geochronological data.

  8. Holographic thermalization

    NARCIS (Netherlands)

    Balasubramanian, V.; Bernamonti, A.; de Boer, J.; Copland, N.; Craps, B.; Keski-Vakkuri, E.; Müller, B.; Schäfer, A.; Shigemori, M.; Staessens, W.

    2011-01-01

    Using the AdS/CFT correspondence, we probe the scale-dependence of thermalization in strongly coupled field theories following a quench, via calculations of two-point functions, Wilson loops and entanglement entropy in d=2,3,4. In the saddlepoint approximation these probes are computed in AdS space

  9. Language experience-dependent advantage in pitch representation in the auditory cortex is limited to favorable signal-to-noise ratios.

    Science.gov (United States)

    Suresh, Chandan H; Krishnan, Ananthanarayan; Gandour, Jackson T

    2017-11-01

    Long-term experience enhances neural representation of temporal attributes of pitch in the brainstem and auditory cortex in favorable listening conditions. Herein we examine whether cortical pitch mechanisms shaped by language experience are more resilient to degradation in background noise, and exhibit greater binaural release from masking (BRM). Cortical pitch responses (CPR) were recorded from Mandarin- and English-speaking natives using a Mandarin word exhibiting a high rising pitch (/yi2/). Stimuli were presented diotically in Quiet, and in noise at +5, and 0 dB SNR. CPRs were also recorded in binaural conditions, SONO (where signal and noise were in phase at both ears); or S0Nπ (where signal was in phase and noise 180° out of phase at each ear), using 0 dB SNR. At Fz, both groups showed increase in CPR peak latency and decrease in amplitude with increasing noise level. A language-dependent enhancement of Na-Pb amplitude (Chinese > English) was restricted to Quiet and +5 dB SNR conditions. At T7/T8 electrode sites, Chinese natives exhibited a rightward asymmetry for both CPR components. A language-dependent effect (Chinese > English) was restricted to T8. Regarding BRM, both CPR components showed greater response amplitude for the S0Nπ condition compared to S0N0 across groups. Rightward asymmetry for BRM in the Chinese group indicates experience-dependent recruitment of right auditory cortex. Restriction of the advantage in pitch representation to the quiet and +5 SNR conditions, and the absence of group differences in the binaural release from masking, suggest that language experience affords limited advantage in the neural representation of pitch-relevant information in the auditory cortex under adverse listening conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Communication and support from health-care professionals to families, with dependent children, following the diagnosis of parental life-limiting illness: A systematic review.

    Science.gov (United States)

    Fearnley, Rachel; Boland, Jason W

    2017-03-01

    Communication between parents and their children about parental life-limiting illness is stressful. Parents want support from health-care professionals; however, the extent of this support is not known. Awareness of family's needs would help ensure appropriate support. To find the current literature exploring (1) how parents with a life-limiting illness, who have dependent children, perceive health-care professionals' communication with them about the illness, diagnosis and treatments, including how social, practical and emotional support is offered to them and (2) how this contributes to the parents' feelings of supporting their children. A systematic literature review and narrative synthesis. Embase, MEDLINE, PsycINFO, CINAHL and ASSIA ProQuest were searched in November 2015 for studies assessing communication between health-care professionals and parents about how to talk with their children about the parent's illness. There were 1342 records identified, five qualitative studies met the inclusion criteria (55 ill parents, 11 spouses/carers, 26 children and 16 health-care professionals). Parents wanted information from health-care professionals about how to talk to their children about the illness; this was not routinely offered. Children also want to talk with a health-care professional about their parents' illness. Health-care professionals are concerned that conversations with parents and their children will be too difficult and time-consuming. Parents with a life-limiting illness want support from their health-care professionals about how to communicate with their children about the illness. Their children look to health-care professionals for information about their parent's illness. Health-care professionals, have an important role but appear reluctant to address these concerns because of fears of insufficient time and expertise.

  11. Temperature dependent impedance spectroscopy and Thermally Stimulated Depolarization Current (TSDC) analysis of disperse red 1-co-poly(methyl methacrylate) copolymers

    Science.gov (United States)

    Ko, Yee Song; Cuervo-Reyes, Eduardo; Nüesch, Frank A.; Opris, Dorina M.

    2016-04-01

    The dielectric relaxation processes of polymethyl methacrylates that have been functionalized with Disperse Red 1 (DR1) in the side chain (DR1-co-MMA) were studied with temperature dependent impedance spectroscopy and thermally stimulated depolarization current (TSDC) techniques. Copolymers with dipole contents which varied between 10 mol% and 70 mol% were prepared. All samples showed dipole relaxations above the structural-glass transition temperature (Tg). The β-relaxation of the methyl methacrylate (MMA) repeating unit was most visible in DR1(10%)-co-MMA and rapidly vanishes with higher dipole contents. DSC data reveal an increase of the Tg by 20 °C to 125°C with the inclusion of the dipole into the polymethyl methacrylate (PMMA) as side chain. The impedance data of samples with several DR1 concentrations, taken at several temperatures above Tg, have been fitted with the Havriliak-Negami (HN) function. In all cases, the fits reveal a dielectric response that corresponds to power-law dipolar relaxations. TSDC measurements show that the copolymer can be poled, and that the induced polarization can be frozen by lowering the temperature well below the glass transition. Relaxation strengths ΔƐ estimated by integrating the depolarization current are similar to those obtained from the impedance data, confirming the efficient freezing of the dipoles in the structural glass state.

  12. Frequency Dependent Non- Thermal Effects of Oscillating Electric Fields in the Microwave Region on the Properties of a Solvated Lysozyme System: A Molecular Dynamics Study.

    Directory of Open Access Journals (Sweden)

    Stelios Floros

    Full Text Available The use of microwaves in every day's applications raises issues regarding the non thermal biological effects of microwaves. In this work we employ molecular dynamics simulations to advance further the dielectric studies of protein solutions in the case of lysozyme, taking into consideration possible frequency dependent changes in the structural and dynamic properties of the system upon application of electric field in the microwave region. The obtained dielectric spectra are identical with those derived in our previous work using the Fröhlich-Kirkwood approach in the framework of the linear response theory. Noticeable structural changes in the protein have been observed only at frequencies near its absorption maximum. Concerning Cα position fluctuations, different frequencies affected different regions of the protein sequence. Furthermore, the influence of the field on the kinetics of protein-water as well as on the water-water hydrogen bonds in the first hydration shell has been studied; an extension of the Luzar-Chandler kinetic model was deemed necessary for a better fit of the applied field results and for the estimation of more accurate hydrogen bond lifetime values.

  13. Nitrogen Gas Flow Ratio and Rapid Thermal Annealing Temperature Dependences of Sputtered Titanium Nitride Gate Work Function and Their Effect on Device Characteristics

    Science.gov (United States)

    Liu, Yongxun; Hayashida, Tetsuro; Matsukawa, Takashi; Endo, Kazuhiko; Masahara, Meishoku; O'uchi, Shinich; Sakamoto, Kunihiro; Ishii, Kenichi; Tsukada, Junichi; Ishikawa, Yuki; Yamauchi, Hiromi; Ogura, Atsushi; Suzuki, Eiichi

    2008-04-01

    A sputtered titanium nitride (TiN) metal gate has systematically been investigated, and the dependences of TiN work function (φTiN) and device performance on nitrogen gas flow ratio [RN=N2/(N2+Ar)] in sputtering and rapid thermal annealing (RTA) temperature (TR) are clarified. It is experimentally found that φTiN slightly decreases from 4.87 to 4.78 eV with increasing RN from 17 to 83%, and it markedly decreases with increasing TR. The analysis of the electrical characteristics of fabricated metal-oxide-semiconductor field-effect transistors (MOSFETs) shows that the optimal RN range is 17-50%, and a higher RN offers a lower Vth owing to the lower φTiN. The origin of φTiN decrease with increasing RN and TR is discussed. The obtained results indicate that φTiN can be controlled by sputtering and RTA conditions, and are very useful for setting the appropriate Vth for lightly doped channel devices such as a FinFET.

  14. Constraining Non-thermal and Thermal properties of Dark Matter

    Directory of Open Access Journals (Sweden)

    Bhupal eDev

    2014-05-01

    Full Text Available We describe the evolution of Dark Matter (DM abundance from the very onset of its creation from inflaton decay under the assumption of an instantaneous reheating. Based on the initial conditions such as the inflaton mass and its decay branching ratio to the DM species, the reheating temperature, and the mass and interaction rate of the DM with the thermal bath, the DM particles can either thermalize (fully/partially with the primordial bath or remain non-thermal throughout their evolution history. In the thermal case, the final abundance is set by the standard freeze-out mechanism for large annihilation rates, irrespective of the initial conditions. For smaller annihilation rates, it can be set by the freeze-in mechanism which also does not depend on the initial abundance, provided it is small to begin with. For even smaller interaction rates, the DM decouples while being non-thermal, and the relic abundance will be essentially set by the initial conditions. We put model-independent constraints on the DM mass and annihilation rate from over-abundance by exactly solving the relevant Boltzmann equations, and identify the thermal freeze-out, freeze-in and non-thermal regions of the allowed parameter space. We highlight a generic fact that inflaton decay to DM inevitably leads to an overclosure of the Universe for a large range of DM parameter space, and thus poses a stringent constraint that must be taken into account while constructing models of DM. For the thermal DM region, we also show the complementary constraints from indirect DM search experiments, Big Bang Nucleosynthesis, Cosmic Microwave Background, Planck measurements, and theoretical limits due to the unitarity of S-matrix. For the non-thermal DM scenario, we show the allowed parameter space in terms of the inflaton and DM masses for a given reheating temperature, and compute the comoving free-streaming length to identify the hot, warm and cold DM regimes.

  15. The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

    Directory of Open Access Journals (Sweden)

    P. Sellitto

    2013-08-01

    Full Text Available Practical implementations of chemical OSSEs (Observing System Simulation Experiments usually rely on approximations of the pseudo-observations by means of a predefined parametrization of the averaging kernels, which describe the sensitivity of the observing system to the target atmospheric species. This is intended to avoid the use of a computationally expensive pseudo-observations simulator, that relies on full radiative transfer calculations. Here we present an investigation on how no, or limited, scene dependent averaging kernels parametrizations may misrepresent the sensitivity of an observing system. We carried out the full radiative transfer calculation for a three-days period over Europe, to produce reference pseudo-observations of lower tropospheric ozone, as they would be observed by a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality. The selected spatio-temporal interval is characterised by an ozone pollution event. We then compared our reference with approximated pseudo-observations, following existing simulation exercises made for both the MAGEAQ and GEOstationary Coastal and Air Pollution Events (GEO-CAPE missions. We found that approximated averaging kernels may fail to replicate the variability of the full radiative transfer calculations. In addition, we found that the approximations substantially overestimate the capability of MAGEAQ to follow the spatio-temporal variations of the lower tropospheric ozone in selected areas, during the mentioned pollution event. We conclude that such approximations may lead to false conclusions if used in an OSSE. Thus, we recommend to use comprehensive scene-dependent approximations of the averaging kernels, in cases where the full radiative transfer is computationally too costly for the OSSE being investigated.

  16. Matching the reaction-diffusion simulation to dynamic [18F]FMISO PET measurements in tumors: extension to a flow-limited oxygen-dependent model.

    Science.gov (United States)

    Shi, Kuangyu; Bayer, Christine; Gaertner, Florian C; Astner, Sabrina T; Wilkens, Jan J; Nüsslin, Fridtjof; Vaupel, Peter; Ziegler, Sibylle I

    2017-02-01

    Positron-emission tomography (PET) with hypoxia specific tracers provides a noninvasive method to assess the tumor oxygenation status. Reaction-diffusion models have advantages in revealing the quantitative relation between in vivo imaging and the tumor microenvironment. However, there is no quantitative comparison of the simulation results with the real PET measurements yet. The lack of experimental support hampers further applications of computational simulation models. This study aims to compare the simulation results with a preclinical [18F]FMISO PET study and to optimize the reaction-diffusion model accordingly. Nude mice with xenografted human squamous cell carcinomas (CAL33) were investigated with a 2 h dynamic [18F]FMISO PET followed by immunofluorescence staining using the hypoxia marker pimonidazole and the endothelium marker CD 31. A large data pool of tumor time-activity curves (TAC) was simulated for each mouse by feeding the arterial input function (AIF) extracted from experiments into the model with different configurations of the tumor microenvironment. A measured TAC was considered to match a simulated TAC when the difference metric was below a certain, noise-dependent threshold. As an extension to the well-established Kelly model, a flow-limited oxygen-dependent (FLOD) model was developed to improve the matching between measurements and simulations. The matching rate between the simulated TACs of the Kelly model and the mouse PET data ranged from 0 to 28.1% (on average 9.8%). By modifying the Kelly model to an FLOD model, the matching rate between the simulation and the PET measurements could be improved to 41.2-84.8% (on average 64.4%). Using a simulation data pool and a matching strategy, we were able to compare the simulated temporal course of dynamic PET with in vivo measurements. By modifying the Kelly model to a FLOD model, the computational simulation was able to approach the dynamic [18F]FMISO measurements in the investigated tumors.

  17. Toxoplasma growth in vitro is dependent on exogenous tyrosine and is independent of AAH2 even in tyrosine-limiting conditions.

    Science.gov (United States)

    Marino, Nicole D; Boothroyd, John C

    2017-05-01

    Toxoplasma gondii is an obligate intracellular parasite capable of infecting virtually all nucleated cell types in almost all warm-blooded animals. Interestingly, Toxoplasma has a relatively full repertoire of amino acid biosynthetic machinery, perhaps reflecting its broad host range and, consequently, its need to adapt to a wide array of amino acid resources. Although Toxoplasma has been shown to be auxotrophic for tryptophan and arginine, it has not previously been determined if Toxoplasma is also auxotrophic for tyrosine. Toxoplasma tachyzoites and bradyzoites were recently found to express an amino acid hydroxylase (AAH2) that is capable of synthesizing tyrosine and dihydroxyphenylalanine (DOPA) from phenylalanine; however, the role of AAH2 in tachyzoite and bradyzoite infection has not yet been identified. To determine if Toxoplasma requires exogenous tyrosine for growth, we performed growth assays on tachyzoites and bradyzoites in nutrient-rich media titrated with varying amounts of tyrosine. We found that Toxoplasma tachyzoites form significantly smaller plaques in tyrosine-limiting media in a dose-dependent manner and that this phenotype is not affected by deletion of TgAAH2. To determine if bradyzoites require exogenous tyrosine for growth, we induced differentiation from tachyzoites in vitro in tyrosine-limiting media and found that replication and vacuole number are all decreased in tyrosine-deficient media. Importantly, culture of confluent human fibroblasts in tyrosine-deficient media does not affect their viability, indicating that, at least in vitro, the need for tyrosine is at the level of Toxoplasma, not the host cell supporting its growth. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Electric Motor Thermal Management R&D. Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, Kevin [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-04-01

    With the push to reduce component volumes, lower costs, and reduce weight without sacrificing performance or reliability, the challenges associated with thermal management increase for power electronics and electric motors. Thermal management for electric motors will become more important as the automotive industry continues the transition to more electrically dominant vehicle propulsion systems. The transition to more electrically dominant propulsion systems leads to higher-power duty cycles for electric drive systems. Thermal constraints place significant limitations on how electric motors ultimately perform, and as thermal management improves, there will be a direct trade-off between motor performance, efficiency, cost, and the sizing of electric motors to operate within the thermal constraints. The goal of this research project is to support broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management. Work in FY15 focused on two areas related to motor thermal management: passive thermal performance and active convective cooling. Passive thermal performance emphasized the thermal impact of materials and thermal interfaces among materials within an assembled motor. The research tasks supported the publication of test methods and data for thermal contact resistances and direction-dependent thermal conductivity within an electric motor. Active convective cooling focused on measuring convective heat-transfer coefficients using automatic transmission fluid (ATF). Data for average convective heat transfer coefficients for direct impingement of ATF jets was published. Also, experimental hardware for mapping local-scale and stator-scale convective heat transfer coefficients for ATF jet impingement were developed.

  19. Local thermal equilibrium for quantum fields on cosmological spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Gransee, Michael [MPI Mathematics in the Sciences, Leipzig (Germany); Universitaet Leipzig (Germany); Knospe, Alexander; Verch, Rainer [Universitaet Leipzig (Germany)

    2011-07-01

    We investigate the consistency of local thermal equilibrium for scalar and Dirac fields on cosmological spacetimes with respect to general covariance and the Hadamard renormalization prescription for the stress-energy tensor. The renormalized stress-energy tensor fulfilling the local thermal equilibrium condition has a thermal part, a dynamical part and a purely geometrical part. The latter contains the renormalization freedom. Since the thermal part differs from the total stress-energy, one finds a temperature dependence on cosmological time which has a stronger singularity in the limit of early cosmological times than in the classical treatment of radiation.

  20. Enriched environment has limited capacity for the correction of hippocampal memory-dependent schizoid behaviors in rats with early postnatal NMDAR dysfunction.

    Science.gov (United States)

    Melik, Enver; Babar, Emine; Kocahan, Sayad; Guven, Mustafa; Akillioglu, Kubra

    2014-04-01

    Pre- and early postnatal stress can cause dysfunction of the N-methyl-d-aspartate receptor (NMDAR) and thereby promote the development of hippocampus memory-dependent schizoid abnormalities of navigation in space, time, and knowledge. An enriched environment improves mental abilities in humans and animals. Whether an enriched environment can prevent the development of schizoid symptoms induced by neonatal NMDAR dysfunction was the central question of our paper. The experimental animals were Wistar rats. Early postnatal NMDAR dysfunction was created by systemic treatment of rat pups with the NMDAR antagonist MK-801 at PD10-20 days. During the development period (PD21-90 days), the rats were reared in cognitively and physically enriched cages. Adult age rats were tested on navigation based on pattern separation and episodic memory in the open field and on auto-hetero-associations based on episodic and semantic memory in a step-through passive avoidance task. The results showed that postnatal NMDAR antagonism caused abnormal behaviors in both tests. An enriched environment prevented deficits in the development of navigation in space based on pattern separation and hetero-associations based on semantic memory. However, an enriched environment was unable to rescue navigation in space and auto-associations based on episodic memory. These data may contribute to the understanding that an enriched environment has a limited capacity for therapeutic interventions in protecting the development of schizoid syndromes in children and adolescents. Copyright © 2013 ISDN. Published by Elsevier Ltd. All rights reserved.

  1. Thermally stable imaging channeled spectropolarimetry

    Science.gov (United States)

    Craven-Jones, Julia; Way, Brandyn M.; Hunt, Jeff; Kudenov, Michael W.; Mercier, Jeffrey A.

    2013-09-01

    Channeled spectropolarimetry can measure the complete polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the spectrally-dependent Stokes polarization information. A primary limitation of conventional channeled spectropolarimeters is related to the thermal variability of the retarders. Thermal variation often forces frequent system recalibration, particularly for field deployed systems. However, implementing thermally stable retarders results in an athermal channeled spectropolarimeter that relieves the need for frequent recalibration. Past work has addressed this issue by developing athermalized retarders using two or more uniaxial crystals. Recently, a retarder made of biaxial KTP and cut at a thermally insensitive angle was used to produce an athermal channeled spectropolarimeter. This paper presents the results of the biaxial crystal system and compares the two thermal stabilization techniques in the context of producing an imaging thermally stable channeled spectropolarimeter. A preliminary design for a snapshot imaging channeled spectropolarimeter is also presented.

  2. A Comparison of Simple Methods to Incorporate Material Temperature Dependency in the Green’s Function Method for Estimating Transient Thermal Stresses in Thick-Walled Power Plant Components

    Science.gov (United States)

    Rouse, James; Hyde, Christopher

    2016-01-01

    The threat of thermal fatigue is an increasing concern for thermal power plant operators due to the increasing tendency to adopt “two-shifting” operating procedures. Thermal plants are likely to remain part of the energy portfolio for the foreseeable future and are under societal pressures to generate in a highly flexible and efficient manner. The Green’s function method offers a flexible approach to determine reference elastic solutions for transient thermal stress problems. In order to simplify integration, it is often assumed that Green’s functions (derived from finite element unit temperature step solutions) are temperature independent (this is not the case due to the temperature dependency of material parameters). The present work offers a simple method to approximate a material’s temperature dependency using multiple reference unit solutions and an interpolation procedure. Thermal stress histories are predicted and compared for realistic temperature cycles using distinct techniques. The proposed interpolation method generally performs as well as (if not better) than the optimum single Green’s function or the previously-suggested weighting function technique (particularly for large temperature increments). Coefficients of determination are typically above 0.96, and peak stress differences between true and predicted datasets are always less than 10 MPa. PMID:28787827

  3. Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction.

    Science.gov (United States)

    Johansson, Johannes D; Eriksson, Ola; Wren, Joakim; Loyd, Dan; Wårdell, Karin

    2006-09-01

    Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders. A small electrode is used to thermally coagulate malfunctioning tissue. Influence on lesion size from thermal and electric conductivity of the tissue, microvascular perfusion and preset electrode temperature was investigated using a finite-element model. Perfusion was modelled as an increased thermal conductivity in non-coagulated tissue. The parameters were analysed using a 2(4)-factorial design (n=16) and quadratic regression analysis (n=47). Increased thermal conductivity of the tissue increased lesion volume, while increased perfusion decreased it since coagulation creates a thermally insulating layer due to the cessation of blood perfusion. These effects were strengthened with increased preset temperature. The electric conductivity had negligible effect. Simulations were found realistic compared to in vivo experimental lesions.

  4. A time-dependent direct current potential drop method to evaluate thickness of an oxide layer formed naturally and thermally on a large surface of carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Md. Rostom, E-mail: engr_rustomfpm@yahoo.com; Saka, Masumi; Tohmyoh, Hironori

    2012-12-15

    This study describes the use of a time-dependent spring-loaded four-point-probe technique to measure the direct current potential drop (DCPD) on oxidized test surfaces for different spring force values, with the purpose of evaluating the thickness of the oxide layer. The force of the spring attached to the current probe was reduced by inserting spacers with different thicknesses under the supporting legs of the sensor block. The PD measurement was first performed on machined sample exposed to the atmosphere for approximately 6 months. The sample was made of carbon steel (SS400). Then, the thickness of the oxide layer formed on the surface of the sample was increased by heat treatment. The PD was also measured on the samples subjected to heat treatment. The measurements were performed at different locations on the test surface under the same experimental conditions. The experimental results establish a relationship between the spring force and the time required for the current probe to penetrate the oxide layer. This article also proposes a procedure for evaluating the thickness of the oxide layer. Finally, the proposed method was used to evaluate the thickness of the oxide layer formed on a large surface. The method was performed to evaluate thickness of single phase monolayer oxide in the range of 3.5-8.7 {mu}m. To demonstrate the validity and accuracy of the proposed method, the obtained thickness was compared to the thickness measured directly using a field emission scanning electron microscopy. - Highlights: Black-Right-Pointing-Pointer Four-point-probe direct current potential drop technique. Black-Right-Pointing-Pointer Naturally and thermally formed oxide layer on a large metallic surface. Black-Right-Pointing-Pointer A procedure for evaluation of thickness of oxide layer formed on hot-rolled steel.

  5. Energy dependence of fission product yields from 235U, 238U, and 239Pu with monoenergetic neutrons between thermal and 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Arnold, Charles; Bhike, Megha; Bredeweg, Todd; Fowler, Malcolm; Krishichayan; Tonchev, Anton; Tornow, Werner; Stoyer, Mark; Vieira, David; Wilhelmy, Jerry

    2017-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements has been performed. The energy dependence of a number of cumulative fission product yields (FPY) have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of fission counting using specially designed dual-fission chambers and γ-ray counting. Each dual-fission chamber is a back-to-back ionization chamber encasing an activation target in the center with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activation target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of two months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6, 5.5, 7.5, 8.9 and 14.8 MeV. Preliminary results from thermal irradiations at the MIT research reactor will also be presented and compared to present data and evaluations. This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Security, LLC under contract DE-AC52-06NA25396, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and by Duke University and Triangle Universities Nuclear Laboratory through NNSA Stewardship Science Academic Alliance grant No. DE-FG52-09NA29465, DE-FG52-09NA29448 and Office of Nuclear Physics Grant No. DE-FG02-97ER41033.

  6. Thermal Ignition

    Science.gov (United States)

    Boettcher, Philipp Andreas

    Accidental ignition of flammable gases is a critical safety concern in many industrial applications. Particularly in the aviation industry, the main areas of concern on an aircraft are the fuel tank and adjoining regions, where spilled fuel has a high likelihood of creating a flammable mixture. To this end, a fundamental understanding of the ignition phenomenon is necessary in order to develop more accurate test methods and standards as a means of designing safer air vehicles. The focus of this work is thermal ignition, particularly auto-ignition with emphasis on the effect of heating rate, hot surface ignition and flame propagation, and puffing flames. Combustion of hydrocarbon fuels is traditionally separated into slow reaction, cool flame, and ignition regimes based on pressure and temperature. Standard tests, such as the ASTM E659, are used to determine the lowest temperature required to ignite a specific fuel mixed with air at atmospheric pressure. It is expected that the initial pressure and the rate at which the mixture is heated also influences the limiting temperature and the type of combustion. This study investigates the effect of heating rate, between 4 and 15 K/min, and initial pressure, in the range of 25 to 100 kPa, on ignition of n-hexane air mixtures. Mixtures with equivalence ratio ranging from 0.6 to 1.2 were investigated. The problem is also modeled computationally using an extension of Semenov's classical auto-ignition theory with a detailed chemical mechanism. Experiments and simulations both show that in the same reactor either a slow reaction or an ignition event can take place depending on the heating rate. Analysis of the detailed chemistry demonstrates that a mixture which approaches the ignition region slowly undergoes a significant modification of its composition. This change in composition induces a progressive shift of the explosion limit until the mixture is no longer flammable. A mixture that approaches the ignition region

  7. Temperature-dependent absorption cross-sections in the thermal infrared bands of SF{sub 5}CF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rinsland, C.P. E-mail: c.p.rinsland@larc.nasa.gov; Sharpe, S.W.; Sams, R.L

    2003-12-15

    Absorption cross-sections have been measured at five temperatures between 213 and 323 K in the infrared bands of SF{sub 5}CF{sub 3}. The spectra were recorded at a resolution of 0.112 cm{sup -1} using a commercial Fourier transform infrared spectrometer and a 20 cm temperature-controlled sample cell. Samples of SF{sub 5}CF{sub 3} were pressurized with high-purity nitrogen to a total pressure of 1013.3 hPa (760 Torr). Six or more spectra with varying SF{sub 5}CF{sub 3} column amounts were analyzed at each temperature. The full spectral range of the measurements was 520-6500 cm{sup -1}, with only weak bands observed beyond 1400 cm{sup -1}. Absorption of thermal radiation in the 8-12 {mu}m atmospheric window region being important for climate change, we report here the integrated cross-sections of the significant absorption bands in that spectral region. Our results closely match room temperature values reported previously. Only small variation of the integrated absorption cross-sections with temperature was found. Our results confirm the accuracy of the previous measurements, which find SF{sub 5}CF{sub 3} important for global climate change on a per molecule basis. Absorption cross-sections derived from a single, near Doppler-limited spectrum recorded at room temperature do not show any rotational fine structure in the 700-950 cm{sup -1} region.

  8. Thermal carrying capacity for a thermally-sensitive species at the warmest edge of its range.

    Directory of Open Access Journals (Sweden)

    Daniel Ayllón

    Full Text Available Anthropogenic environmental change is causing unprecedented rates of population extirpation and altering the setting of range limits for many species. Significant population declines may occur however before any reduction in range is observed. Determining and modelling the factors driving population size and trends is consequently critical to predict trajectories of change and future extinction risk. We tracked during 12 years 51 populations of a cold-water fish species (brown trout Salmo trutta living along a temperature gradient at the warmest thermal edge of its range. We developed a carrying capacity model in which maximum population size is limited by physical habitat conditions and regulated through territoriality. We first tested whether population numbers were driven by carrying capacity dynamics and then targeted on establishing (1 the temperature thresholds beyond which population numbers switch from being physical habitat- to temperature-limited; and (2 the rate at which carrying capacity declines with temperature within limiting thermal ranges. Carrying capacity along with emergent density-dependent responses explained up to 76% of spatio-temporal density variability of juveniles and adults but only 50% of young-of-the-year's. By contrast, young-of-the-year trout were highly sensitive to thermal conditions, their performance declining with temperature at a higher rate than older life stages, and disruptions being triggered at lower temperature thresholds. Results suggest that limiting temperature effects were progressively stronger with increasing anthropogenic disturbance. There was however a critical threshold, matching the incipient thermal limit for survival, beyond which realized density was always below potential numbers irrespective of disturbance intensity. We additionally found a lower threshold, matching the thermal limit for feeding, beyond which even unaltered populations declined. We predict that most of our study

  9. A limited access mouse model of prenatal alcohol exposure that produces long-lasting deficits in hippocampal-dependent learning and memory.

    Science.gov (United States)

    Brady, Megan L; Allan, Andrea M; Caldwell, Kevin K

    2012-03-01

    It has been estimated that approximately 12% of women consume alcohol at some time during their pregnancy, and as many as 5% of children born in the United States are impacted by prenatal alcohol exposure (PAE). The range of physical, behavioral, emotional, and social dysfunctions that are associated with PAE are collectively termed fetal alcohol spectrum disorder (FASD). Using a saccharin-sweetened ethanol solution, we developed a limited access model of PAE. C57BL/6J mice were provided access to a solution of either 10% (w/v) ethanol and 0.066% (w/v) saccharin or 0.066% (w/v) saccharin (control) for 4 h/d. After establishing consistent drinking, mice were mated and continued drinking during gestation. Following parturition, solutions were decreased to 0% in a stepwise fashion over a period of 6 days. Characterization of the model included measurements of maternal consumption patterns, blood ethanol levels, litter size, pup weight, maternal care, and the effects of PAE on fear-conditioned and spatial learning, and locomotor activity. Mothers had mean daily ethanol intake of 7.17 ± 0.17 g ethanol/kg body weight per day, with average blood ethanol concentrations of 68.5 ± 9.2 mg/dl after 2 hours of drinking and 88.3 ± 11.5 mg/dl after 4 hours of drinking. Food and water consumption, maternal weight gain, litter size, pup weight, pup retrieval times, and time on nest did not differ between the alcohol-exposed and control animals. Compared with control offspring, mice that were exposed to ethanol prenatally displayed no difference in spontaneous locomotor activity but demonstrated learning deficits in 3 hippocampal-dependent tasks: delay fear conditioning, trace fear conditioning, and the delay nonmatch to place radial-arm maze task. These results indicate that this model appropriately mimics the human condition of PAE and will be a useful tool in studying the learning deficits seen in FASD. Copyright © 2011 by the Research Society on Alcoholism.

  10. The stability and generation pattern of thermally formed isocyanic acid (ICA) in air - potential and limitations of proton transfer reaction-mass spectrometry (PTR-MS) for real-time workroom atmosphere measurements.

    Science.gov (United States)

    Jankowski, Mikolaj Jan; Olsen, Raymond; Thomassen, Yngvar; Molander, Paal

    2016-07-13

    Isocyanic acid (ICA) in vapour phase has been reported to be of unstable nature, making the occupational hygienic relevance of ICA questionable. The stability of pure ICA in clean air at different humidity conditions was investigated by Fourier transform-infrared spectrometric (FT-IR) measurements. Furthermore, the stability of ICA in a complex atmosphere representative thermal degradation hot-work procedures were examined by performing parallel measurements by proton transfer reaction-mass spectrometric (PTR-MS) instrumentation and off-line denuder air sampling using di-n-butylamine (as a derivatization agent prior to liquid chromatography mass spectrometric (LC-MS) determination). The apparent half-life of ICA in pure ICA atmospheres was 16 to 4 hours at absolute humidity (AH) in the range 4.2 to 14.6 g m(-3), respectively. In a complex atmosphere at an initial AH of 9.6 g m(-3) the apparent half-life of ICA was 8 hours, as measured with the denuder method. Thus, thermally formed ICA is to be considered as a potential occupational hazard with regard to inhalation. The generation pattern of ICA formed during controlled gradient (100-540 °C) thermal decomposition of different polymers in the presence of air was examined by parallel PTR-MS and denuder air sampling. According to measurement by denuder sampling ICA was the dominant aliphatic isocyanate formed during the thermal decomposition of all polymers. The real-time measurements of the decomposed polymers revealed different ICA generation patterns, with initial appearance of thermally released ICA in the temperature range 200-260 °C. The PTR-MS ICA measurements was however affected by mass overlap from other decomposition products at m/z 44, illustrated by a [ICA]Denuder/[ICA]PTR-MS ratio ranging from 0.04 to 0.90. These findings limits the potential use of PTR-MS for real time measurements of thermally released ICA in field, suggesting parallel sampling with short-term sequential off-line methodology.

  11. Divergent thermal specialisation of two South African entomopathogenic nematodes

    Directory of Open Access Journals (Sweden)

    Matthew P. Hill

    2015-07-01

    Full Text Available Thermal physiology of entomopathogenic nematodes (EPN is a critical aspect of field performance and fitness. Thermal limits for survival and activity, and the ability of these limits to adjust (i.e., show phenotypic flexibility depending on recent thermal history, are generally poorly established, especially for non-model nematode species. Here we report the acute thermal limits for survival, and the thermal acclimation-related plasticity thereof for two key endemic South African EPN species, Steinernema yirgalemense and Heterorhabditis zealandica. Results including LT50 indicate S. yirgalemense (LT50 = 40.8 ± 0.3 °C has greater high temperature tolerance than H. zealandica (LT50 = 36.7 ± 0.2 °C, but S. yirgalemense (LT50 = −2.4 ± 0 °C has poorer low temperature tolerance in comparison to H. zealandica (LT50 = −9.7 ± 0.3 °C, suggesting these two EPN species occupy divergent thermal niches to one another.Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant. There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures. At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below −12.5 °C, where after it increased survival. Such results indicate that the thermal niche breadth of EPN species can differ significantly depending on recent thermal conditions, and should be characterized across a broad range of species to understand the evolution of thermal limits to performance and survival in this group.

  12. Well stimulation by downhole thermal methods

    Energy Technology Data Exchange (ETDEWEB)

    Farouq Ali, S.M.

    1973-10-01

    Well-bore thermal stimulation is effective in wells producing either a low gravity, viscous crude, or a high gravity, paraffinic oil. An increase in temperature causes a large decrease in oil viscosity, and solution of waxy deposits, thus eliminating any skin effect. Production problems to be remedied will determine the type of treatment. The degree of production response depends on the formation and fluid characteristics as well as current producing rates. Thermal stimulation can be accomplished by electric or hot water heaters, gas burners, by limited in situ combustion, by hot water or steam injection, and by use of explosives. Each method is briefly described.

  13. Distinct domains within the NITROGEN LIMITATION ADAPTATION protein mediate its subcellular localization and function in the nitrate-dependent phosphate homeostasis pathway

    Science.gov (United States)

    The NITROGEN LIMITATION ADAPTATION (NLA) protein is a RING-type E3 ubiquitin ligase that plays an essential role in the regulation of nitrogen and phosphate homeostasis. NLA is localized to two distinct subcellular sites, the plasma membrane and nucleus, and contains four distinct domains: i) a RING...

  14. Time-dependent thermal state of the lithosphere in the foreland of the Eastern Carpathians bend. Insights from new geothermal measurements and modelling results

    DEFF Research Database (Denmark)

    Demetrescu, Crisan; Wilhelm, H.; Tumanian, M.

    2007-01-01

    in establishing the temperature field in the depth range of geothermal measurements. The lateral variation of the palaeoclimatically corrected surface heat flux from the centre of the Focsani Depression (40 mW m-2) to its margin and the foreland platform (70 mW m-2) is mainly the result of the lateral variation...... words: Carpathians foreland, geothermics, heat flow, lithosphere rheology, sedimentation, thermal modelling.  ...

  15. Reactions of nitroxide radicals in aqueous solutions exposed to non-thermal plasma: limitations of spin trapping of the plasma induced species

    Science.gov (United States)

    Gorbanev, Yury; Stehling, Nicola; O'Connell, Deborah; Chechik, Victor

    2016-10-01

    Low temperature (‘cold’) atmospheric pressure plasmas have gained much attention in recent years due to their biomedical effects achieved through the interactions of plasma-induced species with the biological substrate. Monitoring of the radical species in an aqueous biological milieu is usually performed via electron paramagnetic resonance (EPR) spectroscopy using various nitrone spin traps, which form persistent radical adducts with the short-lived radicals. However, the stability of these nitroxide radical adducts in the plasma-specific environment is not well known. In this work, chemical transformations of nitroxide radicals in aqueous solutions using a model nitroxide 4-oxo-TEMPO were studied using EPR and LC-MS. The kinetics of the nitroxide decay when the solution was exposed to plasma were assessed, and the reactive pathways proposed. The use of different scavengers enabled identification of the types of reactive species which cause the decay, indicating the predominant nitroxide group reduction in oxygen-free plasmas. The 2H adduct of the PBN spin trap (PBN-D) was shown to decay similarly to the model molecule 4-oxo-TEMPO. The decay of the spin adducts in plasma-treated solutions must be considered to avoid rendering the spin trapping results unreliable. In particular, the selectivity of the decay indicated the limitations of the PTIO/PTI nitroxide system in the detection of nitric oxide.

  16. Thickness-dependent crystallization on thermal anneal for titania/silica nm-layer composites deposited by ion beam sputter method.

    Science.gov (United States)

    Pan, Huang-Wei; Wang, Shun-Jin; Kuo, Ling-Chi; Chao, Shiuh; Principe, Maria; Pinto, Innocenzo M; DeSalvo, Riccardo

    2014-12-01

    Crystallization following thermal annealing of thin film stacks consisting of alternating nm-thick titania/silica layers was investigated. Several prototypes were designed, featuring a different number of titania/silica layer pairs, and different thicknesses (in the range from 4 to 40 nm, for the titania layers), but the same nominal refractive index (2.09) and optical thickness (a quarter of wavelength at 1064 nm). The prototypes were deposited by ion beam sputtering on silicon substrates. All prototypes were found to be amorphous as-deposited. Thermal annealing in air at progressive temperatures was subsequently performed. It was found that the titania layers eventually crystallized forming the anatase phase, while the silica layers remained always amorphous. However, progressively thinner layers exhibited progressively higher threshold temperatures for crystallization onset. Accordingly it can be expected that composites with thinner layers will be able to sustain higher annealing temperatures without crystallizing, and likely yielding better optical and mechanical properties for advanced coatings application. These results open the way to the use of materials like titania and hafnia, that crystallize easily under thermal anneal, but ARE otherwise promising candidate materials for HR coatings necessary for cryogenic 3rd generation laser interferometric gravitational wave detectors.

  17. Leaf growth rate per unit thermal time follows QTL-dependent daily patterns in hundreds of maize lines under naturally fluctuating conditions.

    Science.gov (United States)

    Sadok, Walid; Naudin, Philippe; Boussuge, Benoit; Muller, Bertrand; Welcker, Claude; Tardieu, Francois

    2007-02-01

    We have analysed daily patterns of leaf elongation rate (LER) in large data sets with 318 genotypes placed in naturally fluctuating temperature and evaporative demand, and examined the effect of targeted alleles on these patterns. The method consisted, firstly, in expressing elongation rate per unit thermal time, so it became temperature independent; secondly, in a joint analysis of diurnal fluctuations of elongation rate and of micrometeorological conditions in several experiments, and finally, in a comparison of daily patterns between groups of genotypes possessing targeted alleles. (1) Conditions for using thermal time at a time step of 15 min were first tested successfully in 318 recombinant inbred lines (RILs) of three mapping populations. (2) An analysis of 1989 time courses revealed a robust daily pattern of LER per unit thermal time (LERth) over several experiments. LERth was constant during the night and was reproducible (for a given RIL) over up to 10 consecutive nights in different experiments. It declined rapidly during the early morning, closely following the daily pattern of transpiration rate. (3) Groups of RILs carrying alleles conferring a high response to temperature had markedly higher night-time plateau of LER than those with low responses. Groups of RILs with high response to evaporative demand had rapid decreases in elongation rate at the transition between night and day, while this decrease was slower in groups of RILs with low response. These results open the way for using kinetics of responses to environmental stimuli as a phenotyping tool in genetic analyses.

  18. Changes in reactivity and in the margins to thermal limits by the inclusion of control rods of advanced type in the Laguna Verde Power plant; Cambios en la reactividad y en los margenes a limites termicos por la inclusion de barras de control de tipo avanzado en la Central Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, J.L.; Perusquia, R.; Montes, J.L.; Ortiz, J.J.; Ramirez, J.R. [ININ, Depto. de Sistemas Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)]. E-mail: jlhm@nuclear.inin.mx

    2004-07-01

    The obtained results are presented when simulating with CM-PRESTO code the cycle 10 of the unit 1 of the Laguna Verde Central, using two advanced types of control bars, besides the originally loaded ones. The two advanced types, to those that are denominated 1AV and 2AV in this work, are of different design, however both have in some place of the bar, a section with hafnium like neutron absorber material. They thought about three different scenarios, in the first one, used as reference, is simulated the cycle 10 using the original control bars, while in the other two cases the advanced types are used. The values of the reactivity were compared and of some margins to the thermal limits obtained when using the bars of advanced type, with those obtained in the case in that alone they are considered those original bars. It was found that in condition of power both advanced types present bigger absorber power of neutrons that the original bars, being quantified in average this bigger power in 0.22 pcm/notch for the type 1AV and in 0.51 pcm/notch for the type 2AV. The affectation of the margins to the observed thermal limits is minimum. (Author)

  19. Lie group analysis of hydromagnetic flow and heat transfer of a power-law fluid over stretching surface with temperature-dependent viscosity and thermal conductivity

    Science.gov (United States)

    El-Aziz, Mohamed Abd; Afify, Ahmed A.

    2016-07-01

    The symmetry group of MHD boundary layer flow and heat transfer of a non-Newtonian power-law fluid over a stretching surface under the effects of variable fluid properties is investigated. The similarity equations with the corresponding boundary conditions are solved numerically by using a shooting method with the fourth order Runge-Kutta integration scheme. Comparisons of the numerical method with the existing results in the literature are made and obtained an excellent agreement. It is observed that the heat transfer rate diminishes with an increase in magnetic parameter and variable thermal conductivity parameter. Further, the opposite influence is found with an increase in variable viscosity parameter.

  20. Power and Thermal Management of System-on-Chip

    DEFF Research Database (Denmark)

    Liu, Wei

    , are necessary at the chip design level. In this work, we investigate the power and thermal management of System-on- Chips (SoCs). Thermal analysis is performed in a SPICE simulation approach based on the electrical-thermal analogy. We investigate the impact of inter- connects on heat distribution......With greater integration of VLSI circuits, power consumption and power density have increased dramatically resulting in high chip temperatures and presenting a heat removal challenge. To effectively limit the high temperature inside a chip, thermal specific approaches, besides low power techniques...... of power efficient dividers on the energy consumption and thermal distribution within the FPU and the on-chip cache. We also characterize the temperature dependent static dissipation to evaluate the reduction in leakage obtained from the decrease in temperature....

  1. Thermal stress fracture in elastic-brittle materials

    Science.gov (United States)

    Emery, A. F.

    1980-01-01

    The reported investigation shows that the assessment of the possibility of the thermal fracture of brittle materials depends upon an accurate evaluation of the thermal stresses and the determination of the resulting stress intensity factors. The stress intensity factors can be calculated in a variety of ways ranging from the very precise to approximate, but only for a limited number of geometries. The main difficulty is related to the determination of the thermal stress field because of its unusual character and its dependence upon boundary conditions at points far from the region of thermal activity. Examination of a number of examples suggests that the best visualization of the thermal stresses and any associated fracture can be made by considering the problem to be the combination of thermal and isothermal problems or by considering that the prime effect of the temperature is in the generation of thermal strains and that the thermal stresses are simply the result of the region trying to accommodate these strains.

  2. Numeral analysis for Prandtl number dependency on natural convection in an enclosure having a vertical thermal gradient with a square insulator inside

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Ryong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Il Seouk [School of Mechanical Engineering, Kyungpook National University, Daegu (Korea, Republic of)

    2012-04-15

    The natural convection in a horizontal enclosure heated from the bottom wall, cooled at the top wall, and having a square adiabatic body in the center is studied. Three different Prandtl numbers (0.01, 0.7 and 7) are considered for the investigation of the effect of the Prandtl number on natural convection. Adiabatic boundary conditions are employed for the side walls. A two dimensional solution for unsteady natural convection is obtained, using an accurate and efficient Chebyshev spectral methodology for different Rayleigh numbers varying over the range of 103 to 106. It had been experimentally reported that the heat transfer mode becomes oscillatory when Pr is out of a specific Pr band beyond the critical Ra. In this study, we reproduced this phenomenon numerically. It was found that when Ra=106, only the case for intermediate Pr (=0.7) reached a non-changing steady state and the low and high Pr number cases (Pr=0.01 and 7) showed a periodically oscillatory fashion hydro dynamically and thermally. The variation of time- and surface-averaged Nusselt numbers on the hot and cold walls for different Rayleigh numbers and Prandtl numbers are presented to show the overall heat transfer characteristics in the system. Further, the isotherms and streamline distributions are presented in detail to compare the physics related to their thermal behavior.

  3. Investigation of the wavelength dependence of laser stratigraphy on Cu and Ni coatings using LIBS compared to a pure thermal ablation model

    Science.gov (United States)

    Paulis, Evgeniya; Pacher, Ulrich; Weimerskirch, Morris J. J.; Nagy, Tristan O.; Kautek, Wolfgang

    2017-12-01

    In this study, galvanic coatings of Cu and Ni, typically applied in industrial standard routines, were investigated. Ablation experiments were carried out using the first two harmonic wavelengths of a pulsed Nd:YAG laser and the resulting plasma spectra were analysed using a linear Pearson correlation method. For both wavelengths the absorption/ablation behaviour as well as laser-induced breakdown spectroscopy (LIBS) depth profiles were studied varying laser fluences between 4.3-17.2 J/cm^2 at 532 nm and 2.9-11.7 J/cm^2 at 1064 nm. The LIBS-stratigrams were compared with energy-dispersive X-ray spectroscopy of cross-sections. The ablation rates were calculated and compared to theoretical values originating from a thermal ablation model. Generally, higher ablation rates were obtained with 532 nm light for both materials. The light-plasma interaction is suggested as possible cause of the lower ablation rates in the infrared regime. Neither clear evidence of the pure thermal ablation, nor correlation with optical properties of investigated materials was obtained.

  4. Experience-dependent enhancement of pitch-specific responses in the auditory cortex is limited to acceleration rates in normal voice range.

    Science.gov (United States)

    Krishnan, A; Gandour, J T; Suresh, C H

    2015-09-10

    The aim of this study is to determine how pitch acceleration rates within and outside the normal pitch range may influence latency and amplitude of cortical pitch-specific responses (CPR) as a function of language experience (Chinese, English). Responses were elicited from a set of four pitch stimuli chosen to represent a range of acceleration rates (two each inside and outside the normal voice range) imposed on the high rising Mandarin Tone 2. Pitch-relevant neural activity, as reflected in the latency and amplitude of scalp-recorded CPR components, varied depending on language-experience and pitch acceleration of dynamic, time-varying pitch contours. Peak latencies of CPR components were shorter in the Chinese than the English group across stimuli. Chinese participants showed greater amplitude than English for CPR components at both frontocentral and temporal electrode sites in response to pitch contours with acceleration rates inside the normal voice pitch range as compared to pitch contours with acceleration rates that exceed the normal range. As indexed by CPR amplitude at the temporal sites, a rightward asymmetry was observed for the Chinese group only. Only over the right temporal site was amplitude greater in the Chinese group relative to the English. These findings may suggest that the neural mechanism(s) underlying processing of pitch in the right auditory cortex reflect experience-dependent modulation of sensitivity to acceleration in just those rising pitch contours that fall within the bounds of one's native language. More broadly, enhancement of native pitch stimuli and stronger rightward asymmetry of CPR components in the Chinese group is consistent with the notion that long-term experience shapes adaptive, distributed hierarchical pitch processing in the auditory cortex, and reflects an interaction with higher order, extrasensory processes beyond the sensory memory trace. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. Prevalence-dependent decision limits for the early detection of type 2 diabetes mellitus in venous blood, venous plasma and capillary blood during glucose challenge.

    Science.gov (United States)

    Haeckel, Rainer; Raber, Rüdiger; Wosniok, Werner

    2006-01-01

    The glycemia decision limits recommended by WHO/ADA for type 2 diabetes detection are derived from clinical signs in advanced stages of the disease. Since insulin secretion patterns and sensitivitity are impaired at the beginning of type 2 diabetes, this stage may be better suited to identify decision limits with higher diagnostic efficiency than those currently applied. Oral glucose tolerance tests were performed in 300 subjects. Glucose concentrations were measured at 30-min intervals in venous plasma, venous blood and capillary blood. Insulin concentrations in venous plasma, an insulin sensitivity index and body mass index were used to indicate a type 2 diabetic state. A multiple logistic regression procedure was "trained" using only subjects "clearly" considered to be non-diseased or diseased based on an oral glucose tolerance test according to WHO criteria. This insulin algorithm was applied to the whole study group, leading to definitive classification into the non-diseased or the diseased group. This a posteriori classification was used to identify cutoff values with the highest diagnostic efficiency. The diagnostic efficiency was significantly higher when decision limits lower than the WHO recommendations for glucose concentrations were applied in a preselected subpopulation and in all three sample systems tested, e.g., 9.49 mmol/L (171 mg/dL) for venous plasma and 8.94 mmol/L (161 mg/dL) for capillary blood in the 2-h post-load state. The optimized and WHO 2-h cutoff values corresponded to a disease prevalence of 28% and approximately 5% (20% in the fasting state), respectively. Diagnostic efficiency was higher in the 2-h post-load than in the fasting state. Combining fasting values with 2-h post-load values did not further improve the diagnostic efficiency. Glucose concentrations determined from capillary blood were as efficient as those from venous blood or plasma. The number of diabetic subjects detected differed considerably between capillary blood and

  6. Dependent Classes

    DEFF Research Database (Denmark)

    Gasiunas, Vaidas; Mezini, Mira; Ostermann, Klaus

    2007-01-01

    Virtual classes allow nested classes to be refined in subclasses. In this way nested classes can be seen as dependent abstractions of the objects of the enclosing classes. Expressing dependency via nesting, however, has two limitations: Abstractions that depend on more than one object cannot...... be modeled and a class must know all classes that depend on its objects. This paper presents dependent classes, a generalization of virtual classes that expresses similar semantics by parameterization rather than by nesting. This increases expressivity of class variations as well as the flexibility...... of their modularization. Besides, dependent classes complement multi-methods in scenarios where multi-dispatched abstractions rather than multi-dispatched method are needed. They can also be used to express more precise signatures of multi-methods and even extend their dispatch semantics. We present a formal semantics...

  7. Limited influence of aspirin intake on mast cell activation in patients with food-dependent exercise-induced anaphylaxis: comparison using skin prick and histamine release tests.

    Science.gov (United States)

    Fukunaga, Atsushi; Shimizu, Hideki; Tanaka, Mami; Kikuzawa, Ayuko; Tsujimoto, Mariko; Sekimukai, Akiko; Yamashita, Junji; Horikawa, Tatsuya; Nishigori, Chikako

    2012-09-01

    Food-dependent exercise-induced anaphylaxis (FDEIA) is a severe systemic syndrome induced by physical exercise after ingesting causative food. Aspirin is a well-known trigger for anaphylaxis in patients with FDEIA. Possible mechanisms by which symptoms are aggravated by aspirin include enhanced antigen absorption and mast cell activation. The aim of this study was to determine whether aspirin intake has an influence on mast cell/basophil activation in patients with FDEIA. Provocation tests revealed that adding aspirin to the causative food challenge in 7 of 9 (77.8%) patients with FDEIA provoked symptoms. In most cases, pretreatment with aspirin did not enhance skin tests (71.4%) or histamine release tests (88.9%) with food allergen challenges. The study confirms that histamine release and skin prick tests can be adjunctive tools for diagnosing FDEIA. In addition, our results suggest that exacerbation of FDEIA symptoms by aspirin is not mediated by direct effects of aspirin on mast cell/basophil activation.

  8. Utility and limitations of multiplex ligation-dependent probe amplification technique in the detection of cytogenetic abnormalities in products of conception

    Directory of Open Access Journals (Sweden)

    D Saxena

    2016-01-01

    Full Text Available Background and Introduction: Chromosomal abnormality is found in about half of first-trimester abortions. Karyotype is the gold standard to detect chromosomal abnormalities. Multiplex ligation-dependent probe amplification (MLPA offers advantage over karyotype in terms of lower failure rate, faster turnaround time, and much higher resolution than conventional karyotyping and found to be 98% concordant with conventional karyotype. Aim: We performed this study to look for the utility of MLPA in diagnosing chromosomal abnormalities in first-trimester abortions. Materials and Methods: MLPA using subtelomeric SALSA probe sets (P036 and P070 was used to detect cytogenetic abnormalities in products of conception in missed/spontaneous abortions. Results: A total of ninety abortus samples were analyzed by MLPA. Successful results were provided in (67 74.4% of the cases while no conclusion could be drawn in 25.6% (23 of the cases. Fifty-five (82.1% cases were cytogenetically normal and 17.9% (12 had some abnormality. Aneuploidy was detected in 8 (66.7% cases, 3 (25% had double-segment imbalance, and one (8.3% had partial aneuploidy. Conclusion: We suggest that MLPA is a good substitute to traditional karyotype.

  9. Lateral Growth Limitation of Corneal Fibrils and Their Lamellar Stacking Depend on Covalent Collagen Cross-linking by Transglutaminase-2 and Lysyl Oxidases, Respectively*

    Science.gov (United States)

    Wang, Lei; Uhlig, Philipp C.; Eikenberry, Eric F.; Robenek, Horst; Bruckner, Peter; Hansen, Uwe

    2014-01-01

    Corneal stroma contains an extracellular matrix of orthogonal lamellae formed by parallel and equidistant fibrils with a homogeneous diameter of ∼35 nm. This is indispensable for corneal transparency and mechanical functions. However, the mechanisms controlling corneal fibrillogenesis are incompletely understood and the conditions required for lamellar stacking are essentially unknown. Under appropriate conditions, chick embryo corneal fibroblasts can produce an extracellular matrix in vitro resembling primary corneal stroma during embryonic development. Among other requirements, cross-links between fibrillar collagens, introduced by tissue transglutaminase-2, are necessary for the self-assembly of uniform, small diameter fibrils but not their lamellar stacking. By contrast, the subsequent lamellar organization into plywood-like stacks depends on lysyl aldehyde-derived cross-links introduced by lysyl oxidase activity, which, in turn, only weakly influences fibril diameters. These cross-links are introduced at early stages of fibrillogenesis. The enzymes are likely to be important for a correct matrix deposition also during repair of the cornea. PMID:24265319

  10. cGMP-Dependent Protein Kinase Inhibition Extends the Upper Temperature Limit of Stimulus-Evoked Calcium Responses in Motoneuronal Boutons of Drosophila melanogaster Larvae.

    Science.gov (United States)

    Krill, Jennifer L; Dawson-Scully, Ken

    2016-01-01

    While the mammalian brain functions within a very narrow range of oxygen concentrations and temperatures, the fruit fly, Drosophila melanogaster, has employed strategies to deal with a much wider range of acute environmental stressors. The foraging (for) gene encodes the cGMP-dependent protein kinase (PKG), has been shown to regulate thermotolerance in many stress-adapted species, including Drosophila, and could be a potential therapeutic target in the treatment of hyperthermia in mammals. Whereas previous thermotolerance studies have looked at the effects of PKG variation on Drosophila behavior or excitatory postsynaptic potentials at the neuromuscular junction (NMJ), little is known about PKG effects on presynaptic mechanisms. In this study, we characterize presynaptic calcium ([Ca2+]i) dynamics at the Drosophila larval NMJ to determine the effects of high temperature stress on synaptic transmission. We investigated the neuroprotective role of PKG modulation both genetically using RNA interference (RNAi), and pharmacologically, to determine if and how PKG affects presynaptic [Ca2+]i dynamics during hyperthermia. We found that PKG activity modulates presynaptic neuronal Ca2+ responses during acute hyperthermia, where PKG activation makes neurons more sensitive to temperature-induced failure of Ca2+ flux and PKG inhibition confers thermotolerance and maintains normal Ca2+ dynamics under the same conditions. Targeted motoneuronal knockdown of PKG using RNAi demonstrated that decreased PKG expression was sufficient to confer thermoprotection. These results demonstrate that the PKG pathway regulates presynaptic motoneuronal Ca2+ signaling to influence thermotolerance of presynaptic function during acute hyperthermia.

  11. Thermal conductivity of porous structures

    Science.gov (United States)

    Braginsky, L.; Shklover, V.; Witz, G.; Bossmann, H.-P.

    2007-03-01

    Thermal conductivity of porous media is considered. The model permits regular power-series expansion of the expression for thermal conductivity as a function of porosity. The coefficients of the expansion depend on two-site correlation function of local thermal conductivities, which can be calculated from the microscopy image of the structure. Thermal conductivities of some model two-dimensional structures as well as a real porous yttria-stabilized zirconia film are calculated and discussed.

  12. Stochastic losses of fire-dependent endemic herbs revealed by a 65-year chronosequence of dispersal-limited woody plant encroachment.

    Science.gov (United States)

    Brewer, John Stephen

    2017-06-01

    The factors responsible for maintaining diverse groundcover plant communities of high conservation value in frequently burned wet pine savannas are poorly understood. While most management involves manipulating extrinsic factors important in maintaining species diversity (e.g., fire regimes), most ecological theory (e.g., niche theory and neutral theory) examines how traits exhibited by the species promote species coexistence. Furthermore, although many ecologists focus on processes that maintain local species diversity, conservation biologists have argued that other indices (e.g., phylogenetic diversity) are better for evaluating assemblages in terms of their conservation value. I used a null model that employed beta-diversity calculations based on Raup-Crick distances to test for deterministic herbaceous species losses associated with a 65-year chronosequence of woody species encroachment within each of three localities. I quantified conservation value of assemblages by measuring taxonomic distinctness, endemism, and floristic quality of plots with and without woody encroachment. Reductions in herb species richness per plot attributable to woody encroachment were largely stochastic, as indicated by a lack of change in the mean or variance in beta-diversity caused by woody encroachment in the savannas studied here. Taxonomic distinctness, endemism, and floristic quality (when summed across all species) were all greater in areas that had not experienced woody encroachment. However, when corrected for local species richness, only average endemism and floristic quality of assemblages inclusive of herbs and woody plants were greater in areas that had not experienced woody encroachment, due to the more restricted ranges and habitat requirements of herbs. Results suggest that frequent fires maintain diverse assemblages of fire-dependent herb species endemic to the region. The stochastic loss of plant species, irrespective of their taxonomic distinctness, to woody

  13. Change in Vitamin D Levels Occurs Early after Antiretroviral Therapy Initiation and Depends on Treatment Regimen in Resource-Limited Settings

    Science.gov (United States)

    Havers, Fiona P.; Detrick, Barbara; Cardoso, Sandra W.; Berendes, Sima; Lama, Javier R.; Sugandhavesa, Patcharaphan; Mwelase, Noluthando H.; Campbell, Thomas B.; Gupta, Amita

    2014-01-01

    Study Background Vitamin D has wide-ranging effects on the immune system, and studies suggest that low serum vitamin D levels are associated with worse clinical outcomes in HIV. Recent studies have identified an interaction between antiretrovirals used to treat HIV and reduced serum vitamin D levels, but these studies have been done in North American and European populations. Methods Using a prospective cohort study design nested in a multinational clinical trial, we examined the effect of three combination antiretroviral (cART) regimens on serum vitamin D levels in 270 cART-naïve, HIV-infected adults in nine diverse countries, (Brazil, Haiti, Peru, Thailand, India, Malawi, South Africa, Zimbabwe and the United States). We evaluated the change between baseline serum vitamin D levels and vitamin D levels 24 and 48 weeks after cART initiation. Results Serum vitamin D levels decreased significantly from baseline to 24 weeks among those randomized to efavirenz/lamivudine/zidovudine (mean change: −7.94 [95% Confidence Interval (CI) −10.42, −5.54] ng/ml) and efavirenz/emtricitabine/tenofovir-DF (mean change: −6.66 [95% CI −9.40, −3.92] ng/ml) when compared to those randomized to atazanavir/emtricitabine/didanosine-EC (mean change: −2.29 [95% CI –4.83, 0.25] ng/ml). Vitamin D levels did not change significantly between week 24 and 48. Other factors that significantly affected serum vitamin D change included country (p<0.001), season (p<0.001) and baseline vitamin D level (p<0.001). Conclusion Efavirenz-containing cART regimens adversely affected vitamin D levels in patients from economically, geographically and racially diverse resource-limited settings. This effect was most pronounced early after cART initiation. Research is needed to define the role of Vitamin D supplementation in HIV care. PMID:24752177

  14. Estimation of lower flammability limits of C-H compounds in air at atmospheric pressure, evaluation of temperature dependence and diluent effect.

    Science.gov (United States)

    Mendiburu, Andrés Z; de Carvalho, João A; Coronado, Christian R

    2015-03-21

    Estimation of the lower flammability limits of C-H compounds at 25 °C and 1 atm; at moderate temperatures and in presence of diluent was the objective of this study. A set of 120 C-H compounds was divided into a correlation set and a prediction set of 60 compounds each. The absolute average relative error for the total set was 7.89%; for the correlation set, it was 6.09%; and for the prediction set it was 9.68%. However, it was shown that by considering different sources of experimental data the values were reduced to 6.5% for the prediction set and to 6.29% for the total set. The method showed consistency with Le Chatelier's law for binary mixtures of C-H compounds. When tested for a temperature range from 5 °C to 100 °C, the absolute average relative errors were 2.41% for methane; 4.78% for propane; 0.29% for iso-butane and 3.86% for propylene. When nitrogen was added, the absolute average relative errors were 2.48% for methane; 5.13% for propane; 0.11% for iso-butane and 0.15% for propylene. When carbon dioxide was added, the absolute relative errors were 1.80% for methane; 5.38% for propane; 0.86% for iso-butane and 1.06% for propylene. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Opportunities and limits of the one gene approach: the ability of Atoh1 to differentiate and maintain hair cells depends on the molecular context.

    Directory of Open Access Journals (Sweden)

    Israt eJahan

    2015-02-01

    Full Text Available Atoh1 (Math1 was the first gene discovered in ear development that showed no hair cell (HC differentiation when absent and could induce HC differentiation when misexpressed. These data implied that Atoh1 was both necessary and sufficient for hair cell development. However, other gene mutations also result in loss of initially forming HCs, notably null mutants for Pou4f3, Barhl1 and Gfi1. HC development and maintenance also depend on the expression of other genes (Sox2, Eya1, Gata3, Pax2 and several genes have been identified that can induce HCs when misexpressed (Jag1 or knocked out (Lmo4. In the ear Atoh1 is not only expressed in HCs but also in some supporting cells and neurons that do not differentiate into HCs. Simple removal of one gene, Neurod1, can de-repress Atoh1 and turns those neurons into HCs suggesting that Neurod1 blocks Atoh1 function in neurons. Atoh1 expression in inner pillar cells may also be blocked by too many Hes/Hey factors but conversion into HCs has only partially been achieved through Hes/Hey removal. Detailed analysis of cell cycle exit confirmed an apex to base cell cycle exit progression of HCs of the organ of Corti. In contrast, Atoh1 expression progresses from the base towards the apex with a variable delay relative to the cell cycle exit. Most HCs exit the cell cycle and are thus defined as precursors before Atoh1 is expressed. Atoh1 is a potent differentiation factor but can differentiate and maintain HCs only in the ear and when other factors are co-expressed. Upstream factors are essential to regulate Atoh1 level of expression duration while downstream, co-activated by other factors, will define the context of Atoh1 action. We suggest that these insights need to be taken into consideration and approaches beyond the simple Atoh1 expression need to be designed able to generate the radial and longitudinal variations in hair cell types for normal function of the organ of Corti.

  16. Opportunities and limits of the one gene approach: the ability of Atoh1 to differentiate and maintain hair cells depends on the molecular context.

    Science.gov (United States)

    Jahan, Israt; Pan, Ning; Fritzsch, Bernd

    2015-01-01

    Atoh1 (Math1) was the first gene discovered in ear development that showed no hair cell (HC) differentiation when absent and could induce HC differentiation when misexpressed. These data implied that Atoh1 was both necessary and sufficient for hair cell development. However, other gene mutations also result in loss of initially forming HCs, notably null mutants for Pou4f3, Barhl1, and Gfi1. HC development and maintenance also depend on the expression of other genes (Sox2, Eya1, Gata3, Pax2) and several genes have been identified that can induce HCs when misexpressed (Jag1) or knocked out (Lmo4). In the ear Atoh1 is not only expressed in HCs but also in some supporting cells and neurons that do not differentiate into HCs. Simple removal of one gene, Neurod1, can de-repress Atoh1 and turns those neurons into HCs suggesting that Neurod1 blocks Atoh1 function in neurons. Atoh1 expression in inner pillar cells may also be blocked by too many Hes/Hey factors but conversion into HCs has only partially been achieved through Hes/Hey removal. Detailed analysis of cell cycle exit confirmed an apex to base cell cycle exit progression of HCs of the organ of Corti. In contrast, Atoh1 expression progresses from the base toward the apex with a variable delay relative to the cell cycle exit. Most HCs exit the cell cycle and are thus defined as precursors before Atoh1 is expressed. Atoh1 is a potent differentiation factor but can differentiate and maintain HCs only in the ear and when other factors are co-expressed. Upstream factors are essential to regulate Atoh1 level of expression duration while downstream, co-activated by other factors, will define the context of Atoh1 action. We suggest that these insights need to be taken into consideration and approaches beyond the simple Atoh1 expression need to be designed able to generate the radial and longitudinal variations in hair cell types for normal function of the organ of Corti.

  17. Dose-dependent Toxicity of Humanized Renilla reniformis GFP (hrGFP Limits Its Utility as a Reporter Gene in Mouse Muscle

    Directory of Open Access Journals (Sweden)

    Lindsay M Wallace

    2013-01-01

    Full Text Available Gene therapy has historically focused on delivering protein-coding genes to target cells or tissues using a variety of vectors. In recent years, the field has expanded to include gene-silencing strategies involving delivery of noncoding inhibitory RNAs, such as short hairpin RNAs or microRNAs (miRNAs. Often called RNA interference (RNAi triggers, these small inhibitory RNAs are difficult or impossible to visualize in living cells or tissues. To circumvent this detection problem and ensure efficient delivery in preclinical studies, vectors can be engineered to coexpress a fluorescent reporter gene to serve as a marker of transduction. In this study, we set out to optimize adeno-associated viral (AAV vectors capable of delivering engineered miRNAs and green fluorescent protein (GFP reporter genes to skeletal muscle. Although the more broadly utilized enhanced GFP (eGFP gene derived from the jellyfish, Aequorea victoria was a conventional choice, we were concerned about some previous studies suggesting this protein was myotoxic. We thus opted to test vectors carrying the humanized Renilla reniformis-derived GFP (hrGFP gene, which has not seen as extensive usage as eGFP but was purported to be a safer and less cytotoxic alternative. Employing AAV6 vector dosages typically used in preclinical gene transfer studies (3×1010 –1 × 1011 particles, we found that hrGFP caused dose-dependent myopathy when delivered to wild-type (wt mouse muscle, whereas identical titers of AAV6 carrying eGFP were relatively benign. Dose de-escalation at or below 8 × 109 AAV particles effectively reduced or eliminated hrGFP-associated myotoxicity, but also had dampening effects on green fluorescence and miRNA-mediated gene silencing in whole muscles. We conclude that hrGFP is impractical for use as a transduction marker in preclinical, AAV-based RNA interference therapy studies where adult mouse muscle is the target organ. Moreover, our data support that eGFP is superior

  18. A Lumped Thermal Model Including Thermal Coupling and Thermal Boundary Conditions for High Power IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede

    2018-01-01

    Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three......-dimensional thermal models based on Finite Element Method (FEM) need massive computations, which make the long-term thermal dynamics difficult to calculate. In this paper, a new lumped three-dimensional thermal model is proposed, which can be easily characterized from FEM simulations and can acquire the critical...

  19. Study of thermal-field emission properties and investigation of temperature dependent noise in the field emission current from vertical carbon nanotube emitters

    Science.gov (United States)

    Kolekar, Sadhu; Patole, S. P.; Patil, Sumati; Yoo, J. B.; Dharmadhikari, C. V.

    2017-10-01

    We have investigated temperature dependent field electron emission characteristics of vertical carbon nanotubes (CNTs). The generalized expression for electron emission from well-defined cathode surface is given by Millikan and Lauritsen [1] for the combination of temperature and electric field effect. The same expression has been used to explain the electron emission characteristics from vertical CNT emitters. Furthermore, this has been applied to explain the electron emission for different temperatures ranging from room temperature to 1500 K. The real-time field electron emission images at room temperature and 1500 K are recorded by using Charge Coupled Device (CCD) in order to understand the effect of temperature on distribution of electron emission spots and ring like structures in Field Emission Microscope (FEM) image. The FEM images could be used to calculate the total number of emitters per cm2 for electron emission. The calculated number of emitters per cm2 from FEM image is typically, 4.5 × 107 and the actual number emitters per cm2 present as per Atomic Force Microscopy (AFM) data is 1.2 × 1012. The measured Current-Voltage (I-V) characteristics exhibit non linear Folwer-Nordheim (F-N) type behavior. The fluctuations in the emission current were recorded at different temperatures and Fast Fourier transformed into temperature dependent power spectral density. The latter was found to obey power law relation S(f) = A(Iδ/fξ), where δ and ξ are temperature dependent current and frequency exponents respectively.

  20. Ti-thickness-dependent electromigration resistance for Ti/Al-Cu-Si metallization with and without barrier rapid-thermal-anneal in an ammonia ambient

    Science.gov (United States)

    Fu, Kuan Y.; Kawasaki, Hisao; Olowolafe, Johnson O.; Pyle, Ronald E.

    1993-05-01

    The electromigration resistance for Al-Cu-Si alloy over a Ti underlayer as a function of the initial Ti thickness in the range of 0 angstroms - 1000 angstroms is investigated. After the Ti deposition, test structures have been divided into groups with and without a rapid thermal anneal (RTA) in an ammonia ambient to form a TiN barrier. The electromigration resistance of these barrier metallization systems, in general, increases with the initial Ti thickness, except when the initial Ti thickness is less than 600 angstroms for the RTA TiN/Al-Cu-Si system. A model is proposed to explain this electromigration characteristic as a function of the initial Ti thickness for these barrier metallization systems, with the support of texture analysis of the Al-alloy surface and stress measurements of barrier layers using X-ray diffraction and wafer curvature. This study highlights a direction of how a Ti-based barrier metallization system should be processed in order to optimize its electromigration resistance.

  1. Time-dependent categorization of volatile aroma compound formation in stewed Chinese spicy beef using electron nose profile coupled with thermal desorption GC–MS detection

    Directory of Open Access Journals (Sweden)

    Hui Gong

    2017-09-01

    Full Text Available In the present study, flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose, gas chromatography–mass spectrometry (GC–MS with a thermal desorption system (TDS, and solid-phase microextraction (SPME. A total of 82 volatile compounds were identified, and 3-methyl-butanal, pentanal, hexanal, ρ-xylene, heptanal, limonene, terpinene, octanal, linalool, 4-terpinenol, α-terpineol, and (E-anethole were identified as the characteristic flavor compounds in Chinese spiced beef. Variation in the content of volatile components produced by different cooking processes was observed. In general, a cooking time of 4 h resulted in optimal flavor quality and stability. Results indicated that the electronic nose could profile and rapidly distinguish variation among different cooking time. The volatile profiling by TDS-GC–MS and responses from the electronic nose, in combination with multivariate statistical analysis, are a promising tool for control the cooking process of spiced beef.

  2. MHD Flow and Heat Transfer Characteristics in a Casson Liquid Film Towards an Unsteady Stretching Sheet with Temperature-Dependent Thermal Conductivity

    Science.gov (United States)

    Mahmoud, Mostafa A. A.; Megahed, Ahmed M.

    2017-10-01

    Theoretical and numerical outcomes of the non-Newtonian Casson liquid thin film fluid flow owing to an unsteady stretching sheet which exposed to a magnetic field, Ohmic heating and slip velocity phenomena is reported here. The non-Newtonian thermal conductivity is imposed and treated as it vary with temperature. The nonlinear partial differential equations governing the non-Newtonian Casson thin film fluid are simplified into a group of highly nonlinear ordinary differential equations by using an adequate dimensionless transformations. With this in mind, the numerical solutions for the ordinary conservation equations are found using an accurate shooting iteration technique together with the Runge-Kutta algorithm. The lineaments of the thin film flow and the heat transfer characteristics for the pertinent parameters are discussed through graphs. The results obtained here detect many concern for the local Nusselt number and the local skin-friction coefficient in which they may be beneficial for the material processing industries. Furthermore, in some special conditions, the present problem has an excellent agreement with previously published work.

  3. Efflux transporters at the blood-brain barrier limit delivery and efficacy of cyclin-dependent kinase 4/6 inhibitor palbociclib (PD-0332991) in an orthotopic brain tumor model.

    Science.gov (United States)

    Parrish, Karen E; Pokorny, Jenny; Mittapalli, Rajendar K; Bakken, Katrina; Sarkaria, Jann N; Elmquist, William F

    2015-11-01

    6-Acetyl-8-cyclopentyl-5-methyl-2-([5-(piperazin-1-yl)pyridin-2-yl]amino)pyrido(2,3-d)pyrimidin-7(8H)-one [palbociclib (PD-0332991)] is a cyclin-dependent kinase 4/6 inhibitor approved for the treatment of metastatic breast cancer and is currently undergoing clinical trials for many solid tumors. Glioblastoma (GBM) is the most common primary brain tumor in adults and has limited treatment options. The cyclin-dependent kinase 4/6 pathway is commonly dysregulated in GBM and is a promising target in treating this devastating disease. The blood-brain barrier (BBB) limits the delivery of drugs to invasive regions of GBM, where the efflux transporters P-glycoprotein and breast cancer resistance protein can prevent treatments from reaching the tumor. The purpose of this study was to examine the mechanisms limiting the effectiveness of palbociclib therapy in an orthotopic xenograft model. The in vitro intracellular accumulation results demonstrated that palbociclib is a substrate for both P-glycoprotein and breast cancer resistance protein. In vivo studies in transgenic mice confirmed that efflux transport is responsible for the limited brain distribution of palbociclib. There was an ∼115-fold increase in brain exposure at steady state in the transporter deficient mice when compared with wild-type mice, and the efflux inhibitor elacridar significantly increased palbociclib brain distribution. Efficacy studies demonstrated that palbociclib is an effective therapy when GBM22 tumor cells are implanted in the flank, but ineffective in an orthotopic (intracranial) model. Moreover, doses designed to mimic brain exposure were ineffective in treating flank tumors. These results demonstrate that efflux transport in the BBB is involved in limiting the brain distribution of palbociclib and this has critical implications in determining effective dosing regimens of palbociclib therapy in the treatment of brain tumors. Copyright © 2015 by The American Society for Pharmacology and

  4. Study of Thermal-Field Emission Properties and Investigation of Temperature dependent Noise in the Emission Current form vertical Carbon nanotube emitters

    KAUST Repository

    Kolekar, Sadhu

    2017-05-05

    We have investigated temperature dependent field electron emission characteristics of vertical carbon nanotubes (CNTs). The generalized expression for electron emission from well defined cathode surface is given by Millikan and Lauritsen [1] for the combination of temperature and electric field effect. The same expression has been used to explain the electron emission characteristics from vertical CNT emitters. Furthermore, this has been applied to explain the electron emission for different temperatures ranging from room temperature to 1500 K. The real-time field electron emission images at room temperature and 1500 K are recorded by using Charge Coupled Device (CCD), in order to understand the effect of temperature on electron emission spots in image morphology (as indicated by ring like structures) and electron emission spot intensity of the emitters. Moreover, the field electron emission images can be used to calculate the total number of emitters per cm2 for electron emission. The calculated number of emitters per cm2 is 4.5x107 and, the actual number emitters per cm2 present for electron emission calculated from Atomic Force Microscopy (AFM) data is 1.2x1012. The measured Current-Voltage (I-V) characteristics obey the Folwer-Nordheim (F-N) type behavior. The fluctuations in the emission current are recorded at different temperatures and, temperature dependence of power spectral density obeys power law relation s(f)=I2/f2 with that of emission current and frequency.

  5. Limits of the seismogenic zone in the epicentral region of the 26 December 2004 great Sumatra-Andaman earthquake: Results from seismic refraction and wide-angle reflection surveys and thermal modeling

    CERN Document Server

    Klingelhoefer, Frauke; Ladage, S; Dessa, J -X; Graindorge, David; Franke, D; André, C; Permana, Haryadi; Yudistira, T; Chauhan, Ajay; 10.1029/2009JB006569

    2010-01-01

    The 26 December 2004 Sumatra earthquake (Mw = 9.1) initiated around 30 km depth and ruptured 1300 km of the Indo-Australian Sunda plate boundary. During the Sumatra OBS (ocean bottom seismometer) survey, a wide angle seismic profile was acquired across the epicentral region. A seismic velocity model was obtained from combined travel time tomography and forward modeling. Together with reflection seismic data from the SeaCause II cruise, the deep structure of the source region of the great earthquake is revealed. Four to five kilometers of sediments overlie the oceanic crust at the trench, and the subducting slab can be imaged down to a depth of 35 km. We find a crystalline backstop 120 km from the trench axis, below the fore arc basin. A high velocity zone at the lower landward limit of the raycovered domain, at 22 km depth, marks a shallow continental Moho, 170 km from the trench. The deep structure obtained from the seismic data was used to construct a thermal model of the fore arc in order to predict the li...

  6. Thermal performance curves of Paramecium caudatum: a model selection approach.

    Science.gov (United States)

    Krenek, Sascha; Berendonk, Thomas U; Petzoldt, Thomas

    2011-05-01

    The ongoing climate change has motivated numerous studies investigating the temperature response of various organisms, especially that of ectotherms. To correctly describe the thermal performance of these organisms, functions are needed which sufficiently fit to the complete optimum curve. Surprisingly, model-comparisons for the temperature-dependence of population growth rates of an important ectothermic group, the protozoa, are still missing. In this study, temperature reaction norms of natural isolates of the freshwater protist Paramecium caudatum were investigated, considering nearly the entire temperature range. These reaction norms were used to estimate thermal performance curves by applying a set of commonly used model functions. An information theory approach was used to compare models and to identify the best ones for describing these data. Our results indicate that the models which can describe negative growth at the high- and low-temperature branch of an optimum curve are preferable. This is a prerequisite for accurately calculating the critical upper and lower thermal limits. While we detected a temperature optimum of around 29 °C for all investigated clonal strains, the critical thermal limits were considerably different between individual clones. Here, the tropical clone showed the narrowest thermal tolerance, with a shift of its critical thermal limits to higher temperatures. Copyright © 2010 Elsevier GmbH. All rights reserved.

  7. Cryocoolers near their low-temperature limit

    Science.gov (United States)

    de Waele, A. T. A. M.

    2015-07-01

    This paper analyses the recently-observed temperature-time dependence in a GM-cooler near its low-temperature limit. The paper mainly focusses on GM-coolers with 4He as the working fluid, but some attention is also paid to pulse-tube refrigerators (PTR's) using 3He and many features of the treatment equally apply to Stirling coolers. Ample attention is paid to the thermodynamics of the cycle by considering the isentropes in the Tp-diagrams of 4He and 3He. The role of the line, where the thermal expansion coefficient is zero, is emphasized. Some fundamental thermodynamic relationships are derived.

  8. A thermal ground cloak

    Science.gov (United States)

    Yang, Tianzhi; Wu, Qinghe; Xu, Weikai; Liu, Di; Huang, Lujun; Chen, Fei

    2016-02-01

    The thermal cloak has been a long-standing scientific dream of researchers and engineers. Recently thermal metamaterials with man-made micro-structure have been presented based on the principle of transformation optics (TO). This new concept has received considerable attention, which is a powerful tool for manipulating heat flux in thermal imaging systems. However, the inherent material singularity has long been a captivation of experimental realization. As an alternative method, the scattering-cancellation-based cloak (or bi-layer thermal cloak) has been presented to remove the singularity for achieving the same cloaking performance. Nevertheless, such strategy needs prerequisite knowledge (geometry and conductivity) of the object to be cloaked. In this paper, a new thermal ground cloak is presented to overcome the limitations. The device is designed, fabricated and measured to verify the thermal cloaking performance. We experimentally show that the remarkably low complexity of the device can fully and effectively be manipulated using realizable transformation thermal devices. More importantly, this thermal ground cloak is designed to exclude heat flux without knowing the information of the cloaked object.

  9. Hydrodynamic Simulation of Non-thermal Pressure Profiles of Galaxy Clusters

    OpenAIRE

    Nelson, Kaylea; Lau, Erwin T.; Nagai, Daisuke

    2014-01-01

    Cosmological constraints from X-ray and microwave observations of galaxy clusters are subjected to systematic uncertainties. Non-thermal pressure support due to internal gas motions in galaxy clusters is one of the major sources of astrophysical uncertainties. Using a mass-limited sample of galaxy clusters from a high-resolution hydrodynamical cosmological simulation, we characterize the non-thermal pressure fraction profile and study its dependence on redshift, mass, and mass accretion rate....

  10. Cortisol-induced masculinization: does thermal stress affect gonadal fate in pejerrey, a teleost fish with temperature-dependent sex determination?

    Directory of Open Access Journals (Sweden)

    Ricardo S Hattori

    Full Text Available BACKGROUND: Gonadal fate in many reptiles, fish, and amphibians is modulated by the temperature experienced during a critical period early in life (temperature-dependent sex determination; TSD. Several molecular processes involved in TSD have been described but how the animals "sense" environmental temperature remains unknown. We examined whether the stress-related hormone cortisol mediates between temperature and sex differentiation of pejerrey, a gonochoristic teleost fish with marked TSD, and the possibility that it involves glucocorticoid receptor- and/or steroid biosynthesis-modulation. METHODOLOGY/PRINCIPAL FINDINGS: Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males consistently had higher cortisol, 11-ketotestoterone (11-KT, and testosterone (T titres than those at a feminizing temperature (17 degrees C; 100% females. Cortisol-treated animals had elevated 11-KT and T, and showed a typical molecular signature of masculinization including amh upregulation, cyp19a1a downregulation, and higher incidence of gonadal apoptosis during sex differentiation. Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR agonist (Dexamethasone to larvae at a "sexually neutral" temperature (24 degrees C caused significant increases in the proportion of males. CONCLUSIONS/SIGNIFICANCE: Our results suggest a role of cortisol in the masculinization of pejerrey and provide a possible link between stress and testicular differentiation in this gonochoristic TSD species. Cortisol role or roles during TSD of pejerrey seem(s to involve both androgen biosynthesis- and GR-mediated processes. These findings and recent reports of cortisol effects on sex determination of sequential hermaphroditic fishes, TSD reptiles, and birds provide support to the notion that stress responses might be involved in various forms of environmental sex determination.

  11. Effects of Black Hole Spin on the Limit-Cycle Behaviour of Accretion ...

    Indian Academy of Sciences (India)

    We present a spatially 1.5-dimensional, time-dependent numerical study of accretion disks around Kerr black holes. Our study focuses on the limit-cycle behavior of thermally unstable accretion disks. We find that maximal luminosity may be a more appropriate probe of black hole spin than the cycle duration and influence ...

  12. The Dielectric Bolometer, A New Type of Thermal Radiation Detector

    Science.gov (United States)

    Hanel, R. A.

    1960-01-01

    Thermal detectors for the infrared, such as thermocouples and bolometers, are limited in their ultimate sensitivity predominantly by Johnson noise rather than temperature noise. Low noise figures are hard to achieve since Johnson noise preponderates temperature noise, which is the only essential noise for thermal detectors. The dielectric constants of some materials are sufficiently temperature dependent to make a new type of bolometer feasible. The basic theory of a dielectric bolometer, as shown here, promises noise figures below 3 decibels even at chopper frequencies well above the 1/tau value of the detector. Ferroelectrics such as barium-strontium titanate and others seem to be well suited for radiation-cooled dielectric bolometers.

  13. Thermal Management and Thermal Protection Systems

    Science.gov (United States)

    Hasnain, Aqib

    2016-01-01

    During my internship in the Thermal Design Branch (ES3), I contributed to two main projects: i) novel passive thermal management system for future human exploration, ii) AVCOAT undercut thermal analysis. i) As NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be challenged with unprecedented thermal environments. Future exploration activities will have the need of thermal management systems that can provide higher reliability, mass and power reduction and increased performance. In an effort to start addressing the current technical gaps the NASA Johnson Space Center Passive Thermal Discipline has engaged in technology development activities. One of these activities was done through an in-house Passive Thermal Management System (PTMS) design for a lunar lander. The proposed PTMS, functional in both microgravity and gravity environments, consists of three main components: a heat spreader, a novel hybrid wick Variable Conductance Heat Pipe (VCHP), and a radiator. The aim of this PTMS is to keep electronics on a vehicle within their temperature limits (0 and 50 C for the current design) during all mission phases including multiple lunar day/night cycles. The VCHP was tested to verify its thermal performance. I created a thermal math model using Thermal Desktop (TD) and analyzed it to predict the PTMS performance. After testing, the test data provided a means to correlate the thermal math model. This correlation took into account conduction and convection heat transfer, representing the actual benchtop test. Since this PTMS is proposed for space missions, a vacuum test will be taking place to provide confidence that the system is functional in space environments. Therefore, the model was modified to include a vacuum chamber with a liquid nitrogen shroud while taking into account conduction and radiation heat transfer. Infrared Lamps were modelled and introduced into the model to simulate the sun

  14. Predicting urban outdoor thermal comfort by the Universal Thermal Climate Index UTCI--a case study in Southern Brazil.

    Science.gov (United States)

    Bröde, Peter; Krüger, Eduardo L; Rossi, Francine A; Fiala, Dusan

    2012-05-01

    Recognising that modifications to the physical attributes of urban space are able to promote improved thermal outdoor conditions and thus positively influence the use of open spaces, a survey to define optimal thermal comfort ranges for passers-by in pedestrian streets was conducted in Curitiba, Brazil. We applied general additive models to study the impact of temperature, humidity, and wind, as well as long-wave and short-wave radiant heat fluxes as summarised by the recently developed Universal Thermal Climate Index (UTCI) on the choice of clothing insulation by fitting LOESS smoothers to observations from 944 males and 710 females aged from 13 to 91 years. We further analysed votes of thermal sensation compared to predictions of UTCI. The results showed that females chose less insulating clothing in warm conditions compared to males and that observed values of clothing insulation depended on temperature, but also on season and potentially on solar radiation. The overall pattern of clothing choice was well reflected by UTCI, which also provided for good predictions of thermal sensation votes depending on the meteorological conditions. Analysing subgroups indicated that the goodness-of-fit of the UTCI was independent of gender and age, and with only limited influence of season and body composition as assessed by body mass index. This suggests that UTCI can serve as a suitable planning tool for urban thermal comfort in sub-tropical regions.

  15. Modeling of Temperature-Dependent Noise in Silicon Nanowire FETs including Self-Heating Effects

    OpenAIRE

    Anandan, P.; Malathi, N.; Mohankumar, N.

    2014-01-01

    Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resi...

  16. Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

    Science.gov (United States)

    Elzouka, Mahmoud

    This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

  17. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  18. Electrochemical-thermal modeling and microscale phase change for passive internal thermal management of lithium ion batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, Thomas F. (Georgia Institute of Technology, Atlanta, GA); Bandhauer, Todd (Georgia Institute of Technology, Atlanta, GA); Garimella, Srinivas (Georgia Institute of Technology, Atlanta, GA)

    2012-01-01

    A fully coupled electrochemical and thermal model for lithium-ion batteries is developed to investigate the impact of different thermal management strategies on battery performance. In contrast to previous modeling efforts focused either exclusively on particle electrochemistry on the one hand or overall vehicle simulations on the other, the present work predicts local electrochemical reaction rates using temperature-dependent data on commercially available batteries designed for high rates (C/LiFePO{sub 4}) in a computationally efficient manner. Simulation results show that conventional external cooling systems for these batteries, which have a low composite thermal conductivity ({approx}1 W/m-K), cause either large temperature rises or internal temperature gradients. Thus, a novel, passive internal cooling system that uses heat removal through liquid-vapor phase change is developed. Although there have been prior investigations of phase change at the microscales, fluid flow at the conditions expected here is not well understood. A first-principles based cooling system performance model is developed and validated experimentally, and is integrated into the coupled electrochemical-thermal model for assessment of performance improvement relative to conventional thermal management strategies. The proposed cooling system passively removes heat almost isothermally with negligible thermal resistances between the heat source and cooling fluid. Thus, the minimization of peak temperatures and gradients within batteries allow increased power and energy densities unencumbered by thermal limitations.

  19. Registry Effect on the Thermal Conductivity of Few-Layer Graphene

    OpenAIRE

    Jiang, Jin-Wu

    2014-01-01

    We perform molecular dynamics simulations to study the registry effect on the thermal conductivity of few-layer graphene. The interlayer interaction is described by either the Lennard-Jones potential or the registry-dependent potential. Our calculations show that the thermal conductivity in few-layer graphene from both potentials are close to each other, i.e the registry effect is essentially not important. It is because the thermal transport in few-layer graphene is mainly limited by the int...

  20. Exploration of pH-dependent behavior of the anion receptor pocket of subdomain IIA of HSA: determination of effective pocket charge using the Debye-Hückel limiting law.

    Science.gov (United States)

    Bolel, Priyanka; Datta, Shubhashis; Mahapatra, Niharendu; Halder, Mintu

    2014-01-09

    Protein-ligand electrostatic interaction can be looked upon as ion receptor-ligand interaction, and the binding cavity of protein can be either an anion or cation receptor depending on the charge of the guest. Here we focus on the exploration of pH-modulated binding of a number of anionic ligands, specific to the subdomain IIA cavity of HSA, such as carmoisine, tartrazine, cochineal red, and warfarin. The logarithm of the binding constant is found to vary linearly with the square-root of ionic strength, indicating applicability of the Debye-Hückel limiting law to protein-ligand electrostatic binding equilibrium, and concludes that the subdomain IIA cavity is an anion receptor. The present approach is very unique that one can calculate the effective charge of the protein-based anion receptor pocket, and the calculated charge has been found to vary between +1 and +3 depending on the pH and ligand itself. The study also indicates that in such cases of specific ligand binding the pocket charge rather than the overall or surface charge of the macromolecule seems to have a paramount role in determining the strength of interaction. For the first time, it is demonstrated that the Debye-Hückel interionic interaction model can be successfully applied to understand the protein-based receptor-ligand electrostatic interaction in general.

  1. Limiting Skepticism

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Symons, John

    2011-01-01

    Skeptics argue that the acquisition of knowledge is impossible given the standing possibility of error. We present the limiting convergence strategy for responding to skepticism and discuss the relationship between conceivable error and an agent’s knowledge in the limit. We argue that the skeptic...

  2. Prediction of Thermal Environment in a Large Space Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Hyun-Jung Yoon

    2018-02-01

    Full Text Available Since the thermal environment of large space buildings such as stadiums can vary depending on the location of the stands, it is important to divide them into different zones and evaluate their thermal environment separately. The thermal environment can be evaluated using physical values measured with the sensors, but the occupant density of the stadium stands is high, which limits the locations available to install the sensors. As a method to resolve the limitations of installing the sensors, we propose a method to predict the thermal environment of each zone in a large space. We set six key thermal factors affecting the thermal environment in a large space to be predicted factors (indoor air temperature, mean radiant temperature, and clothing and the fixed factors (air velocity, metabolic rate, and relative humidity. Using artificial neural network (ANN models and the outdoor air temperature and the surface temperature of the interior walls around the stands as input data, we developed a method to predict the three thermal factors. Learning and verification datasets were established using STAR CCM+ (2016.10, Siemens PLM software, Plano, TX, USA. An analysis of each model’s prediction results showed that the prediction accuracy increased with the number of learning data points. The thermal environment evaluation process developed in this study can be used to control heating, ventilation, and air conditioning (HVAC facilities in each zone in a large space building with sufficient learning by ANN models at the building testing or the evaluation stage.

  3. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  4. Thermal conductivity measurements of particulate materials under Martian conditions

    Science.gov (United States)

    Presley, M. A.; Christensen, P. R.

    1993-01-01

    The mean particle diameter of surficial units on Mars has been approximated by applying thermal inertia determinations from the Mariner 9 Infrared Radiometer and the Viking Infrared Thermal Mapper data together with thermal conductivity measurement. Several studies have used this approximation to characterize surficial units and infer their nature and possible origin. Such interpretations are possible because previous measurements of the thermal conductivity of particulate materials have shown that particle size significantly affects thermal conductivity under martian atmospheric pressures. The transfer of thermal energy due to collisions of gas molecules is the predominant mechanism of thermal conductivity in porous systems for gas pressures above about 0.01 torr. At martian atmospheric pressures the mean free path of the gas molecules becomes greater than the effective distance over which conduction takes place between the particles. Gas particles are then more likely to collide with the solid particles than they are with each other. The average heat transfer distance between particles, which is related to particle size, shape and packing, thus determines how fast heat will flow through a particulate material.The derived one-to-one correspondence of thermal inertia to mean particle diameter implies a certain homogeneity in the materials analyzed. Yet the samples used were often characterized by fairly wide ranges of particle sizes with little information about the possible distribution of sizes within those ranges. Interpretation of thermal inertia data is further limited by the lack of data on other effects on the interparticle spacing relative to particle size, such as particle shape, bimodal or polymodal mixtures of grain sizes and formation of salt cements between grains. To address these limitations and to provide a more comprehensive set of thermal conductivities vs. particle size a linear heat source apparatus, similar to that of Cremers, was assembled to

  5. Quantum-Limited Spectroscopy

    CERN Document Server

    Truong, Gar-Wing; May, Eric F; Stace, Thomas M; Luiten, Andre N

    2015-01-01

    Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a ten-fold improvement in the accuracy of the excited-state (6P$_{1/2}$) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity-dispersion of the Cs vapour with an uncertainty of 35ppm within an hour. This allows us to determine a value for Boltzm...

  6. Theoretical investigation of some thermal effects in turbulence modeling

    Energy Technology Data Exchange (ETDEWEB)

    Mathelin, Lionel [LIMSI-CNRS, Orsay (France); Bataille, Francoise [PROMES-CNRS, Perpignan (France); Ye, Zhou [Lawrence Livermore National Lab., Livermore, CA (United States)

    2008-11-15

    Fluid compressibility effects arising from thermal rather than dynamical aspects are theoretically investigated in the framework of turbulent flows. The Mach number is considered low and not to induce significant compressibility effects which here occur due to a very high thermal gradient within the flowfield. With the use of the Two-Scale Direct Interaction Approximation approach, essential turbulent correlations are derived in a one-point one-time framework. In the low velocity gradient limit, they are shown to directly depend on the temperature gradient, assumed large. The impact of thermal effects onto the transport equations of the turbulent kinetic energy and dissipation rate is also investigated, together with the transport equation for both the density and the internal energy variance.

  7. Thermographic measurement of thermal bridges in buildings under dynamic behavior

    Science.gov (United States)

    Ferrarini, G.; Bison, P.; Bortolin, A.; Cadelano, G.; De Carli, M.

    2016-05-01

    The accurate knowledge of the thermal performance could reduce significantly the impact of buildings on global energy consumption. Infrared thermography is widely recognized as one of the key technologies for building surveys, thanks to its ability to acquire at a glance thermal images of the building envelope. However, a spot measurement could be misleading when the building is under dynamic thermal conditions. In this case data should be acquired for hours or days, depending on the thermal properties of the walls. Long term thermographic monitoring are possible but imply strong challenges from a practical standpoint. This work investigates the possibilities and limitations of spot thermographic surveys coupled with contact probes, that are able to acquire continuously the thermal signal for days, to investigate the thermal bridges of a building. The goal is the estimation of the reliability and accuracy of the measurement under realistic environmental conditions. Firstly, numerical simulations are performed to determine the reference value of an experimental case. Then a long term thermographic survey is performed and integrated with the contact probe measurement, assessing the feasibility of the method.

  8. Thermal Properties of G-348 Graphite

    Energy Technology Data Exchange (ETDEWEB)

    McEligot, Donald M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Swank, W. David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cottle, David L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Valentin, Francisco I. [City Univ. (CUNY), NY (United States)

    2017-04-01

    Fundamental measurements have been obtained in the INL Graphite Characterization Laboratory to deduce the temperature dependence of thermal conductivity for G-348 isotropic graphite, which has been used by City College of New York in thermal experiments related to gas-cooled nuclear reactors. Measurements of thermal diffusivity, mass, volume and thermal expansion were converted to thermal conductivity in accordance with ASTM Standard Practice C781-08 (R-2014). Data are tabulated and a preliminary correlation for the thermal conductivity is presented as a function of temperature from laboratory temperature to 1000C.

  9. Limited clinical efficacy of azacitidine in transfusion-dependent, growth factor-resistant, low- and Int-1-risk MDS: Results from the nordic NMDSG08A phase II trial.

    Science.gov (United States)

    Tobiasson, M; Dybedahl, I; Holm, M S; Karimi, M; Brandefors, L; Garelius, H; Grövdal, M; Högh-Dufva, I; Grønbæk, K; Jansson, M; Marcher, C; Nilsson, L; Kittang, A O; Porwit, A; Saft, L; Möllgård, L; Hellström-Lindberg, E

    2014-03-07

    This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks and a transfusion need of 4 units over 8 weeks were included. Aza 75 mg m(-2) d(-1), 5/28 days, was given for six cycles; non-responding patients received another three cycles combined with Epo 60 000 units per week. Primary end point was transfusion independence (TI). All patients underwent targeted mutational screen for 42 candidate genes. Thirty enrolled patients received one cycle of Aza. Ten patients discontinued the study early, 7 due to adverse events including 2 deaths. Thirty-eight serious adverse events were reported, the most common being infection. Five patients achieved TI after six cycles and one after Aza+Epo, giving a total response rate of 20%. Mutational screening revealed a high frequency of recurrent mutations. Although no single mutation predicted for response, SF3A1 (n=3) and DNMT3A (n=4) were only observed in non-responders. We conclude that Aza can induce TI in severely anemic MDS patients, but efficacy is limited, toxicity substantial and most responses of short duration. This treatment cannot be generally recommended in lower-risk MDS. Mutational screening revealed a high frequency of mutations.

  10. Probing Anisotropic Thermal Conductivity of Transition Metal Dichalcogenides MX2 (M = Mo, W and X = S, Se) using Time-Domain Thermoreflectance.

    Science.gov (United States)

    Jiang, Puqing; Qian, Xin; Gu, Xiaokun; Yang, Ronggui

    2017-09-01

    Transition metal dichalcogenides (TMDs) are a group of layered 2D semiconductors that have shown many intriguing electrical and optical properties. However, the thermal transport properties in TMDs are not well understood due to the challenges in characterizing anisotropic thermal conductivity. Here, a variable-spot-size time-domain thermoreflectance approach is developed to simultaneously measure both the in-plane and the through-plane thermal conductivity of four kinds of layered TMDs (MoS2 , WS2 , MoSe2 , and WSe2 ) over a wide temperature range, 80-300 K. Interestingly, it is found that both the through-plane thermal conductivity and the Al/TMD interface conductance depend on the modulation frequency of the pump beam for all these four compounds. The frequency-dependent thermal properties are attributed to the nonequilibrium thermal resistance between the different groups of phonons in the substrate. A two-channel thermal model is used to analyze the nonequilibrium phonon transport and to derive the intrinsic thermal conductivity at the thermal equilibrium limit. The measurements of the thermal conductivities of bulk TMDs serve as an important benchmark for understanding the thermal conductivity of single- and few-layer TMDs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Quantum Speed Limits for Leakage and Decoherence.

    Science.gov (United States)

    Marvian, Iman; Lidar, Daniel A

    2015-11-20

    We introduce state-independent, nonperturbative Hamiltonian quantum speed limits for population leakage and fidelity loss, for a gapped open system interacting with a reservoir. These results hold in the presence of initial correlations between the system and the reservoir, under the sole assumption that their interaction and its commutator with the reservoir Hamiltonian are norm bounded. The reservoir need not be thermal and can be time dependent. We study the significance of energy mismatch between the system and the local degrees of freedom of the reservoir that directly interact with the system. We demonstrate that, in general, by increasing the system gap we may reduce this energy mismatch, and, consequently, drive the system and the reservoir into resonance; this can accelerate fidelity loss, irrespective of the thermal properties or state of the reservoir. This implies that quantum error suppression strategies based on increasing the gap are not uniformly beneficial. Our speed limits also yield an elementary lower bound on the relaxation time of spin systems.

  12. Thermalization in a holographic confining gauge theory

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Takaaki [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); Kiritsis, Elias [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); APC, University Paris Diderot, Sorbonne Paris Cité, UMR 7164 CNRS,10, rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Rosen, Christopher [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece)

    2015-08-03

    Time dependent perturbations of states in the holographic dual of a 3+1 dimensional confining theory are considered. The perturbations are induced by varying the coupling to the theory’s most relevant operator. The dual gravitational theory belongs to a class of Einstein-dilaton theories which exhibit a mass gap at zero temperature and a first order deconfining phase transition at finite temperature. The perturbation is realized in various thermal bulk solutions by specifying time dependent boundary conditions on the scalar, and we solve the fully backreacted Einstein-dilaton equations of motion subject to these boundary conditions. We compute the characteristic time scale of many thermalization processes, noting that in every case we examine, this time scale is determined by the imaginary part of the lowest lying quasi-normal mode of the final state black brane. We quantify the dependence of this final state on parameters of the quench, and construct a dynamical phase diagram. Further support for a universal scaling regime in the abrupt quench limit is provided.

  13. Thermal quench at finite 't Hooft coupling

    Directory of Open Access Journals (Sweden)

    H. Ebrahim

    2016-03-01

    Full Text Available Using holography we have studied thermal electric field quench for infinite and finite 't Hooft coupling constant. The set-up we consider here is D7-brane embedded in (α′ corrected AdS-black hole background. It is well-known that due to a time-dependent electric field on the probe brane, a time-dependent current will be produced and it will finally relax to its equilibrium value. We have studied the effect of different parameters of the system on equilibration time. As the most important results, for massless fundamental matter, we have observed a universal behaviour in the rescaled equilibration time in the very fast quench regime for different values of the temperature and α′ correction parameter. It seems that in the slow quench regime the system behaves adiabatically. We have also observed that the equilibration time decreases in finite 't Hooft coupling limit.

  14. Theoretical Research on Thermal Shock Resistance of Ultra-High Temperature Ceramics Focusing on the Adjustment of Stress Reduction Factor

    Directory of Open Access Journals (Sweden)

    Daining Fang

    2013-02-01

    Full Text Available The thermal shock resistance of ceramics depends on not only the mechanical and thermal properties of materials, but also the external constraint and thermal condition. So, in order to study the actual situation in its service process, a temperature-dependent thermal shock resistance model for ultra-high temperature ceramics considering the effects of the thermal environment and external constraint was established based on the existing theory. The present work mainly focused on the adjustment of the stress reduction factor according to different thermal shock situations. The influences of external constraint on both critical rupture temperature difference and the second thermal shock resistance parameter in either case of rapid heating or cooling conditions had been studied based on this model. The results show the necessity of adjustment of the stress reduction factor in different thermal shock situations and the limitations of the applicable range of the second thermal shock resistance parameter. Furthermore, the model was validated by the finite element method.

  15. Thermal comfort

    DEFF Research Database (Denmark)

    d’Ambrosio Alfano, Francesca Romana; Olesen, Bjarne W.; Palella, Boris Igor

    2014-01-01

    Thermal comfort is one of the most important aspects of the indoor environmental quality due to its effects on well-being, people's performance and building energy requirements. Its attainment is not an easy task requiring advanced design and operation of building and HVAC systems, taking...... under specific conditions. At operation level, only few variables are taken into account with unpredictable effects on the assessment of comfort indices. In this paper, the main criteria for the design and assessment of thermal comfort are discussed in order to help building and HVAC systems designers...... into account all parameters involved. Even though thermal comfort fundamentals are consolidated topics for more than forty years, often designers seem to ignore or apply them in a wrong way. Design input values from standards are often considered as universal values rather than recommended values to be used...

  16. Solar thermal conversion

    Science.gov (United States)

    Selcuk, M. K.

    1978-01-01

    A brief review of the fundamentals of the conversion of solar energy into mechanical work (or electricity via generators) is given. Both past and present work on several conversion concepts are discussed. Solar collectors, storage systems, energy transport, and various types of engines are examined. Ongoing work on novel concepts of collectors, energy storage and thermal energy conversion are outlined and projections for the future are described. Energy costs for various options are predicted and margins and limitations are discussed.

  17. Nanowires for thermal energy conversion and management

    Science.gov (United States)

    Chen, Renkun

    This dissertation presents the application of nanowires in two aspects of thermal energy conversion and management: (i) silicon (Si) nanowires as efficient and scalable thermoelectric materials due to the reduced thermal conductivity (k), and (ii) Si and copper (Cu) nanowire arrays for enhanced phase change heat transfer including boiling and evaporation and their applications in thermal management of microelectronics. In the first half of the thesis (chapter 2 and 3), we describe thermal and thermoelectric measurements of individual Si nanowires for studying phonon transport properties and their potential application in thermoelectrics. A theoretical model based on coherent phonon scattering was developed to explain the experiemental data, which suggests that phonon-boundary scattering is highly frequency dependent. For low frequency (long wavelength) phonons, the transport is nearly ballistic, whereas high frequency or short wavelength phonons scatter diffusively at nanowire boundary. The competition between the two phonon transmission regimes results in the unusual linear behavior of the thermal conductance of thin VLS Si nanowires at low temperature. Next, the thermal conductivity of EE Si nanowires, which have much rougher surface compared to VLS nanowires, was measured and found to be five-eight times lower than that of VLS counterparts with similar diameters. The substantial reduction in k is presumably due to the higher surface roughness, since both types of nanowires have single crystalline cores. In particular, for ˜ 50 nm EE Si nanowires etched from 0.1 O-cm B-doped p-Si (˜2 x 1017 cm-3 dopant concentration), the k is around 1.6 Wm-1K-1 and the kL is ˜1.2 Wm-1 K-1 at room temperature, approaching that of amorphous Si. The single nanowire measurements show the great promise of using Si nanowire arrays as high-performance, scalable thermoelectric materials. As the second focus of the thesis (chapter 4 and 5), nanowire arrays were used for enhanced phase

  18. Thermal stress relaxation in magnesium composites during thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Trojanova, Z.; Lukac, P. (Karlova Univ., Prague (Czech Republic)); Kiehn, J.; Kainer, K.U.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany))

    1998-01-01

    It has been shown that the internal friction of Mg - Saffil metal matrix composites can be influenced by thermal stresses, if MMCc are submitted to thermal cycling between room temperature and an upper temperature of cycling. These stresses can be accommodated by generation and motion of dislocations giving the formation of the microplastic zones. The thermal stress relaxation depends on the upper temperature of cycling, the volume fraction of reinforcement and the matrix composition and can result in plastic deformation and strain hardening of the matrix without applied stress. The internal friction measurements can be used for non destructive investigation of processes which influence the mechanical properties. (orig.)

  19. Information-limiting correlations

    Science.gov (United States)

    Moreno-Bote, Rubén; Beck, Jeffrey; Kanitscheider, Ingmar; Pitkow, Xaq; Latham, Peter; Pouget, Alexandre

    2015-01-01

    Computational strategies used by the brain strongly depend on the amount of information that can be stored in population activity, which in turn strongly depends on the pattern of noise correlations. In vivo, noise correlations tend to be positive and proportional to the similarity in tuning properties. Such correlations are thought to limit information, which has led to the suggestion that decorrelation increases information. In contrast, we found, analytically and numerically, that decorrelation does not imply an increase in information. Instead, the only information-limiting correlations are what we refer to as differential correlations: correlations proportional to the product of the derivatives of the tuning curves. Unfortunately, differential correlations are likely to be very small and buried under correlations that do not limit information, making them particularly difficult to detect. We found, however, that the effect of differential correlations on information can be detected with relatively simple decoders. PMID:25195105

  20. Thermal defoliation

    Science.gov (United States)

    The negative perception some consumers hold regarding agricultural chemicals has resulted in an increased demand for organic foods and fibers, and in increasing political pressure for the regulation of agricultural production practices. This has revived interest in thermal defoliation of cotton and ...

  1. Colloidal Thermal Fluids

    Science.gov (United States)

    Lotzadeh, Saba

    In this dissertation, a reversible system with a well controlled degree of particle aggregation was developed. By surface modification of colloidal silica with aminosilanes, interactions among the particles were tuned in a controlled way to produce stable sized clusters at different pH values ranges from well-disposed to a colloidal gel. N-[3-(trimethoxysilyl)propyl]ethylenediamine (TMPE) monolayer on particle surface not only removes all the reactive sites to prevent chemical aggregation, also provides steric stabilization in the absence of any repulsion. After surface modification, electrokinetic behavior of silica particles were changed to that of amino groups, positive in acidic pH and neutral at basic pH values. By tuning the pH, the balance between electrostatic repulsion and hydrophobic interactions was reversibly controlled. As a result, clusters with different sizes were developed. The effect of clustering on the thermal conductivity of colloidal dispersions was quantified using silane-treated silica, a system engineered to exhibit reversible clustering under well-controlled conditions. Thermal conductivity of this system was measured by transient hot wire, the standard method of thermal conductivity measurements in liquids. We show that the thermal conductivity increases monotonically with cluster size and spans the entire range between the two limits of Maxwell's theory. The results, corroborated by numerical simulation, demonstrate that large increases of the thermal conductivity of colloidal dispersions are possible, yet fully within the predictions of classical theory. Numerical calculations were performed to evaluate the importance of structural properties of particles/aggregates on thermal conduction in colloidal particles. Thermal conductivity of non-spherical particles including hollow particles, cubic particles and rods was studied using a Monte Carlo algorithm. We show that anisotropic shapes, increase conductivity above that of isotropic

  2. Quantum cryptography approaching the classical limit.

    Science.gov (United States)

    Weedbrook, Christian; Pirandola, Stefano; Lloyd, Seth; Ralph, Timothy C

    2010-09-10

    We consider the security of continuous-variable quantum cryptography as we approach the classical limit, i.e., when the unknown preparation noise at the sender's station becomes significantly noisy or thermal (even by as much as 10(4) times greater than the variance of the vacuum mode). We show that, provided the channel transmission losses do not exceed 50%, the security of quantum cryptography is not dependent on the channel transmission, and is therefore incredibly robust against significant amounts of excess preparation noise. We extend these results to consider for the first time quantum cryptography at wavelengths considerably longer than optical and find that regions of security still exist all the way down to the microwave.

  3. Nanoscale heat engine beyond the Carnot limit.

    Science.gov (United States)

    Roßnagel, J; Abah, O; Schmidt-Kaler, F; Singer, K; Lutz, E

    2014-01-24

    We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the efficiency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the efficiency at maximum power of up to a factor of 4 is reached, largely exceeding the Carnot bound.

  4. Power Electronics Thermal Control (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, S.

    2010-05-05

    Thermal management plays an important part in the cost of electric drives in terms of power electronics packaging. Very promising results have been obtained by using microporous coatings and skived surfaces in conjunction with single-phase and two-phase flows. Sintered materials and thermoplastics with embedded fibers show significant promise as thermal interface materials, or TIMs. Appropriate cooling technologies depend on the power electronics package application and reliability.

  5. Thermal Hardware for the Thermal Analyst

    Science.gov (United States)

    Steinfeld, David

    2015-01-01

    The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Space Flight Center (GSFC) Thermal Engineering Branch (Code 545). NCTS 21070-1. Most Thermal analysts do not have a good background into the hardware which thermally controls the spacecraft they design. SINDA and Thermal Desktop models are nice, but knowing how this applies to the actual thermal hardware (heaters, thermostats, thermistors, MLI blanketing, optical coatings, etc...) is just as important. The course will delve into the thermal hardware and their application techniques on actual spacecraft. Knowledge of how thermal hardware is used and applied will make a thermal analyst a better engineer.

  6. Dispersion stability of thermal nanofluids

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2017-10-01

    Full Text Available Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a long-existing issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed. Keywords: Thermal nanofluids, Dispersion, Aggregation, Electrostatic stabilization, Steric stabilization

  7. The thermodynamic limits of magnetic recording

    Science.gov (United States)

    Richter, H. J.; Lyberatos, A.; Nowak, U.; Evans, R. F. L.; Chantrell, R. W.

    2012-02-01

    Thermal stability of the recorded information is generally thought to set the limit of the maximum possible density in magnetic recording. It is shown that basic thermodynamics always cause the probability of success of the write process to be less than 100%. This leads to a thermally induced error rate, which eventually limits the maximum possible density beyond that given by the traditional thermal stability limit. While the thermally induced error rate is negligible for recording of simple single domain particles, it rapidly increases in the presence of a write assist, in particular if the write assist is accomplished by an increased recording temperature. For the ultimate recording system that combines thermally assisted writing with a recording scheme that uses one grain per bit, the upper bound for the maximum achievable density is 20 Tbit/inch2 for a bit error rate target of 10-2.

  8. Limits on $\

    CERN Document Server

    Perego, D L

    2002-01-01

    A limit on the tau neutrino mass is obtained using all the $Z^{0} \\to \\tau^{+} \\tau^{-}$ data collected at LEP by the DELPHI detector between 1992 and 1995. In this analysis events in which one of the taus decays into one charged particle, while the second $\\tau$ decays into f{}ive charged pions (1-5 topology) have been used. The neutrino mass is determined from a bidimensional \\fit ~on the invariant mass $m^{*}_{5 \\pi}$ and on the energy $E_{5 \\pi}$ of the f{}ive $\\pi^{\\pm}$ system. The result found is $m_{\

  9. Thermal Clothing

    Science.gov (United States)

    1997-01-01

    Gateway Technologies, Inc. is marketing and developing textile insulation technology originally developed by Triangle Research and Development Corporation. The enhanced thermal insulation stems from Small Business Innovation Research contracts from NASA's Johnson Space Center and the U.S. Air Force. The effectiveness of the insulation comes from the microencapsulated phase-change materials originally made to keep astronauts gloved hands warm. The applications for the product range from outer wear, housing insulation, and blankets to protective firefighting gear and scuba diving suits. Gateway has developed and begun marketing thermal regulating products under the trademark, OUTLAST. Products made from OUTLAST are already on the market, including boot and shoe liners, winter headgear, hats and caps for hunting and other outdoor sports, and a variety of men's and women's ski gloves.

  10. Turbulent Thermalization

    CERN Document Server

    Micha, Raphael; Micha, Raphael; Tkachev, Igor I.

    2004-01-01

    We study, analytically and with lattice simulations, the decay of coherent field oscillations and the subsequent thermalization of the resulting stochastic classical wave-field. The problem of reheating of the Universe after inflation constitutes our prime motivation and application of the results. We identify three different stages of these processes. During the initial stage of ``parametric resonance'', only a small fraction of the initial inflaton energy is transferred to fluctuations in the physically relevant case of sufficiently large couplings. A major fraction is transfered in the prompt regime of driven turbulence. The subsequent long stage of thermalization classifies as free turbulence. During the turbulent stages, the evolution of particle distribution functions is self-similar. We show that wave kinetic theory successfully describes the late stages of our lattice calculation. Our analytical results are general and give estimates of reheating time and temperature in terms of coupling constants and...

  11. THERMAL INSULATION SYSTEMS

    Science.gov (United States)

    Augustynowicz, Stanislaw D. (Inventor); Fesmire, James E. (Inventor)

    2005-01-01

    Thermal insulation systems and with methods of their production. The thermal insulation systems incorporate at least one reflection layer and at least one spacer layer in an alternating pattern. Each spacer layer includes a fill layer and a carrier layer. The fill layer may be separate from the carrier layer, or it may be a part of the carrier layer, i.e., mechanically injected into the carrier layer or chemically formed in the carrier layer. Fill layers contain a powder having a high surface area and low bulk density. Movement of powder within a fill layer is restricted by electrostatic effects with the reflection layer combined with the presence of a carrier layer, or by containing the powder in the carrier layer. The powder in the spacer layer may be compressed from its bulk density. The thermal insulation systems may further contain an outer casing. Thermal insulation systems may further include strips and seams to form a matrix of sections. Such sections serve to limit loss of powder from a fill layer to a single section and reduce heat losses along the reflection layer.

  12. A map of the non-thermal WIMP

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungjin, E-mail: hjkim06@kaist.ac.kr [Department of Physics, KAIST, Daejeon 34141 (Korea, Republic of); Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS), Daejeon 34051 (Korea, Republic of); Hong, Jeong-Pyong, E-mail: hjp0731@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Shin, Chang Sub, E-mail: changsub.shin@apctp.org [Asia Pacific Center for Theoretical Physics, Pohang 37673 (Korea, Republic of); Department of Physics, Postech, Pohang 37673 (Korea, Republic of)

    2017-05-10

    We study the effect of the elastic scattering on the non-thermal WIMP, which is produced by direct decay of heavy particles at the end of reheating. The non-thermal WIMP becomes important when the reheating temperature is well below the freeze-out temperature. Usually, two limiting cases have been considered. One is that the produced high energetic dark matter particles are quickly thermalized due to the elastic scattering with background radiations. The corresponding relic abundance is determined by the thermally averaged annihilation cross-section at the reheating temperature. The other one is that the initial abundance is too small for the dark matter to annihilate so that the final relic is determined by the initial amount itself. We study the regions between these two limits, and show that the relic density depends not only on the annihilation rate, but also on the elastic scattering rate. Especially, the relic abundance of the p-wave annihilating dark matter crucially relies on the elastic scattering rate because the annihilation cross-section is sensitive to the dark matter velocity. We categorize the parameter space into several regions where each region has distinctive mechanism for determining the relic abundance of the dark matter at the present Universe. The consequence on the (in)direct detection is also studied.

  13. Optical-thermal light-tissue interactions during photoacoustic breast imaging.

    Science.gov (United States)

    Gould, Taylor; Wang, Quanzeng; Pfefer, T Joshua

    2014-03-01

    Light-tissue interactions during photoacoustic imaging, including dynamic heat transfer processes in and around vascular structures, are not well established. A three-dimensional, transient, optical-thermal computational model was used to simulate energy deposition, temperature distributions and thermal damage in breast tissue during exposure to pulsed laser trains at 800 and 1064 nm. Rapid and repetitive temperature increases and thermal relaxation led to superpositioning effects that were highly dependent on vessel diameter and depth. For a ten second exposure at established safety limits, the maximum single-pulse and total temperature rise levels were 0.2°C and 5.8°C, respectively. No significant thermal damage was predicted. The impact of tissue optical properties, surface boundary condition and irradiation wavelength on peak temperature location and temperature evolution with time are discussed.

  14. Limiting characteristics of a superconducting quantum interferometer. II. Signal-to-noise ratio

    Energy Technology Data Exchange (ETDEWEB)

    Butikov, E.I.; Feofilov, S.P.

    1980-11-01

    In the approximation of small fluctuations, the spectral density of intrinsic thermal noise limiting the maximal sensitivity of a constant-current SQUID is found in the low-frequency region. The dependence of the signal-to-noise ratio on the SQUID parameters and operating conditions of an interferometer with low-frequency magnetic flux modulation is studied. Estimates are given for the smallest detectable magnetic flux corresponding to optimal operating conditions of a SQUID.

  15. THERMAL CONDUCTIVITY OF NON-REPOSITORY LITHOSTRATIGRAPHIC LAYERS

    Energy Technology Data Exchange (ETDEWEB)

    R. JONES

    2004-10-22

    from each test specimen to meet three specific conditions: (1) Known value for matrix porosity; (2) Known values for wet and dry thermal conductivity; and (3) The location of the measured specimen in relation to the model stratigraphic unit. The only matrix thermal conductivity values developed are limited to fully saturated and dry conditions. The model does not include the effects of convection and thermal radiation in voids. The model does not include temperature dependence of thermal conductivity, porosity, or bulk density.

  16. Thermal drawdown and recovery of singly and multiply fractured hot dry rock reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Wunder, R.; Murphy, H.

    1978-04-01

    To calculate heat extraction and thermal recovery in hot dry rock geothermal reservoirs, a computer code was written to solve the differential equations for rock-water heat conduction and convection by finite differences. Temperature versus time functions for multiple fractures separated by various spacings are presented in dimensional and in nondimensional plots. The results were specialized for the limiting case of a single fracture in unbounded rock and for the other limiting case where the rock is so extensively fractured that thermal breakthrough phenomena can occur. Fracture temperatures were calculated during the thermal recovery following various extraction periods. For the single-fracture case these temperature recoveries could, with slight approximation, be represented as a single curve depending only upon the ratio of the total elapsed time and the extraction time.

  17. Subsystem eigenstate thermalization hypothesis

    Science.gov (United States)

    Dymarsky, Anatoly; Lashkari, Nima; Liu, Hong

    2018-01-01

    Motivated by the qualitative picture of canonical typicality, we propose a refined formulation of the eigenstate thermalization hypothesis (ETH) for chaotic quantum systems. This formulation, which we refer to as subsystem ETH, is in terms of the reduced density matrix of subsystems. This strong form of ETH outlines the set of observables defined within the subsystem for which it guarantees eigenstate thermalization. We discuss the limits when the size of the subsystem is small or comparable to its complement. In the latter case we outline the way to calculate the leading volume-proportional contribution to the von Neumann and Renyi entanglment entropies. Finally, we provide numerical evidence for the proposal in the case of a one-dimensional Ising spin chain.

  18. Limites térmicos para a germinação em função da origem de sementes de espécies de Eugenia (Myrtaceae nativas do Brasil Thermal requirements for the seeds of Brazilian species of Eugenia (Myrtaceae according to their origin

    Directory of Open Access Journals (Sweden)

    Edmir Vicente Lamarca

    2011-06-01

    Full Text Available A germinação das sementes é dependente de numerosos fatores abióticos, dentre os quais a temperatura figura entre os principais. No presente estudo analisou-se o comportamento germinativo de sementes de E. brasiliensis, E. involucrata, E. pyriformis e E. uniflora em resposta a diferentes condições de luz e temperatura, incluindo-se o cálculo da soma térmica durante o desenvolvimento e maturação das sementes. Os resultados demonstraram que a germinação de sementes e o desenvolvimento de plântulas normais ocorreram adequadamente na faixa de 20 ºC a 30 ºC. Nessa faixa, as sementes foram indiferentes à luz e à alternância de temperatura para a germinação. Especifi camente para Eugenia pyriformis, avaliaram-se temperaturas superiores a 30 ºC e inferiores a 20 ºC, verifi cando-se que as sementes germinaram na faixa térmica de 10 ºC a 35 ºC, mas não a 5 ºC e a 40 ºC; os maiores valores de germinação e de IVG foram observados a 25 ºC e 30 ºC. Ficou evidente que a secagem modifica os limites e exigências térmicas para a germinação das sementes de E. pyriformis, uma vez que os maiores níveis de desidratação resultaram em maiores prejuízos à germinação fora da faixa térmica ótima. As sementes de E. pyriformis coletadas em Lavras, MG, que receberam maior quantidade de graus-dia durante o desenvolvimento e a maturação, apresentaram melhor desempenho em relação às sementes coletadas em Campinas, SP e em São Paulo, SP.Seed germination is dependent on several abiotic factors including temperature. In this study, we analyzed the germination of seeds of Eugenia brasiliensis, E. involucrata, E. pyriformis and E. uniflora in response to diff erent conditions of light and temperature. Seeds of all species showed high germination values from 20 to 30 ºC. Germination of seeds of E. Pyriformis was also evaluated at temperatures higher than 30 ºC and lower than 20 ºC. The germination and the normal seedling

  19. Thermal insulator

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, R.; Asada, Y.; Matsuo, Y.; Mikoda, M.

    1985-07-16

    A thermal insulator comprises an expanded resin body having embedded therein an evacuated powder insulation portion which consists of fine powder and a container of film-like plastics or a film-like composite of plastics and metal for enclosing the powder. The resin body has been expanded by a Freon gas as a blowing agent. Since a Freon gas has a larger molecular diameter than the constituent gases of air, it is less likely to permeate through the container than air. Thus present invention provides a novel composite insulator which fully utilizes the benefits of vacuum insulation without necessitating a strong and costly material for a vacuum container.

  20. Forensic analysis methodology for thermal and chemical characterization of homemade explosives

    Energy Technology Data Exchange (ETDEWEB)

    Nazarian, Ashot; Presser, Cary, E-mail: cpresser@nist.gov

    2014-01-20

    Highlights: • Identification of homemade explosives (HME) is critical for determining the origin of explosive precursor materials. • A novel laser-heating technique was used to obtain the thermal/chemical signatures of HME precursor materials. • Liquid-fuel saturation of the pores of a solid porous oxidizer affected the total specific heat release. • Material thermal signatures were dependent on sample mass and heating rate. • This laser-heating technique can be a useful diagnostic tool for characterizing the thermochemical behavior of HMEs. - Abstract: Forensic identification of homemade explosives is critical for determining the origin of the explosive materials and precursors, and formulation procedures. Normally, the forensic examination of the pre- and post-blast physical evidence lacks specificity for homemade-explosive identification. The focus of this investigation was to use a novel measurement technique, referred to as the laser-driven thermal reactor, to obtain the thermal/chemical signatures of homemade-explosive precursor materials. Specifically, nitromethane and ammonium nitrate were studied under a variety of operating conditions and protocols. Results indicated that liquid-fuel saturation of the internal pores of a solid particle oxidizer appear to be a limiting parameter for the total specific heat release during exothermic processes. Results also indicated that the thermal signatures of these materials are dependent on sample mass and heating rate, for which this dependency may not be detectable by other commercially available thermal analysis techniques. This study has demonstrated that the laser-driven thermal reactor can be a useful diagnostic tool for characterizing the thermal and chemical behavior of trace amounts of homemade-explosive materials.

  1. Significant Reduction of Graphene Thermal Conductivity by Phononic Crystal Structure

    OpenAIRE

    Yang, Lina; CHEN, JIE; Yang, Nuo; Li, Baowen

    2014-01-01

    We studied the thermal conductivity of graphene phononic crystal (GPnC), also named as graphene nanomesh, by molecular dynamics simulations. The dependences of thermal conductivity of GPnCs on both length and temperature are investigated. It is found that the thermal conductivity of GPnCs is significantly lower than that of graphene and can be efficiently tuned by changing the porosity and period length. For example, the ratio of thermal conductivity of GPnC to thermal conductivity of graphen...

  2. Thermal conductivity of mass-graded graphene flakes

    OpenAIRE

    Cheh, Jigger; Zhao, Hong

    2011-01-01

    In this letter we study thermal conduction in mass-graded graphene flakes by nonequilibrium molecular dynamics simulations. It is found that mass-graded graphene flakes reveal no thermal rectification effect in thermal conduction process. The dependence of thermal conductivity upon the heat flux and the mass gradient are studied to confirm the generality of the result.The mechanism leading to the absence of thermal rectification effect is also discussed.

  3. Green's function retrieval and passive imaging from correlations of wideband thermal radiations.

    Science.gov (United States)

    Davy, Matthieu; Fink, Mathias; de Rosny, Julien

    2013-05-17

    We present an experimental demonstration of electromagnetic Green's function retrieval from thermal radiations in anechoic and reverberant cavities. The Green's function between two antennas is estimated by cross correlating milliseconds of decimeter noise. We show that the temperature dependence of the cross-correlation amplitude is well predicted by the blackbody theory in the Rayleigh-Jeans limit. The effect of a nonuniform temperature distribution on the cross-correlation time symmetry is also explored. Finally, we open a new way to image scatterers using ambient thermal radiations.

  4. Analytical evaluation of thermal conductance and heat capacities of one-dimensional material systems

    Energy Technology Data Exchange (ETDEWEB)

    Saygi, Salih [Department of Physics, Gaziosmanpasa University, Tokat, 60200 Turkey (Turkey)

    2014-02-15

    We theoretically predict some thermal properties versus temperature dependence of one dimensional (1D) material nanowire systems. A known method is used to provide an efficient and reliable analytical procedure for wide temperature range. Predicted formulas are expressed in terms of Bloch-Grüneisen functions and Debye functions. Computing results has proved that the expressions are in excellent agreement with the results reported in the literature even if it is in very low dimension limits of nanowire systems. Therefore the calculation method is a fully predictive approach to calculate thermal conductivity and heat capacities of nanowire material systems.

  5. Path Dependency

    OpenAIRE

    Mark Setterfield

    2015-01-01

    Path dependency is defined, and three different specific concepts of path dependency – cumulative causation, lock in, and hysteresis – are analyzed. The relationships between path dependency and equilibrium, and path dependency and fundamental uncertainty are also discussed. Finally, a typology of dynamical systems is developed to clarify these relationships.

  6. Implication of thermal discharges into the sea - A review

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumar, V.; Sastry, J.S.; Swamy, G.N.

    The adverse effects of thermal discharges into coastal waters from power plants have been reviewed. The direct and indirect impacts of thermal pollution to marine biota have been discussed briefly. The tolerance limits documented elsewhere have been...

  7. Hydrodynamic simulation of non-thermal pressure profiles of galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Kaylea; Nagai, Daisuke [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Lau, Erwin T., E-mail: kaylea.nelson@yale.edu [Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520 (United States)

    2014-09-01

    Cosmological constraints from X-ray and microwave observations of galaxy clusters are subjected to systematic uncertainties. Non-thermal pressure support due to internal gas motions in galaxy clusters is one of the major sources of astrophysical uncertainties. Using a mass-limited sample of galaxy clusters from a high-resolution hydrodynamical cosmological simulation, we characterize the non-thermal pressure fraction profile and study its dependence on redshift, mass, and mass accretion rate. We find that the non-thermal pressure fraction profile is universal across redshift when galaxy cluster radii are defined with respect to the mean matter density of the universe instead of the commonly used critical density. We also find that the non-thermal pressure is predominantly radial, and the gas velocity anisotropy profile exhibits strong universality when galaxy cluster radii are defined with respect to the mean matter density of the universe. However, we find that the non-thermal pressure fraction is strongly dependent on the mass accretion rate of the galaxy cluster. We provide fitting formulae for the universal non-thermal pressure fraction and velocity anisotropy profiles of gas in galaxy clusters, which should be useful in modeling astrophysical uncertainties pertinent to using galaxy clusters as cosmological probes.

  8. Thermal conductivity of local moment models with strong spin-orbit coupling

    Science.gov (United States)

    Stamokostas, Georgios L.; Lapas, Panteleimon E.; Fiete, Gregory A.

    2017-02-01

    We study the magnetic and lattice contributions to the thermal conductivity of electrically insulating strongly spin-orbit coupled magnetically ordered phases on a two-dimensional honeycomb lattice using the Kitaev-Heisenberg model. Depending on model parameters, such as the relative strength of the spin-orbit induced anisotropic coupling, a number of magnetically ordered phases are possible. In this work, we study two distinct regimes of thermal transport depending on whether the characteristic energy of the phonons or the magnons dominates, and focus on two different relaxation mechanisms, boundary scattering and magnon-phonon scattering. For spatially anisotropic magnetic phases, the thermal conductivity tensor can be highly anisotropic when the magnetic energy scale dominates, since the magnetic degrees of freedom dominate the thermal transport for temperatures well below the magnetic transition temperature. In the opposite limit in which the phonon energy scale dominates, the thermal conductivity will be nearly isotropic, reflecting the isotropic (at low temperatures) phonon dispersion assumed for the honeycomb lattice. We further discuss the extent to which thermal transport properties are influenced by strong spin-orbit induced anisotropic coupling in the local moment regime of insulating magnetic phases. The developed methodology can be applied to any 2D magnon-phonon system, and more importantly to systems where an analytical Bogoliubov transformation cannot be found and magnon bands are not necessarily isotropic.

  9. Effect of metallic nanoparticle fillers on the thermal conductivity of diatomaceous earth

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, Mouhamad S. [Department of Liberal Arts, Des Moines Area Community College, Des Moines, IA 50314 (United States); Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Srinivasan, Srilok [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Chang, Boyce [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Ghosh, Suvojit [Department of Engineering Physics, McMaster University, Hamilton, ON L8S4L8 (Canada); Balasubramanian, Ganesh, E-mail: bganesh@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States)

    2016-10-23

    Thermal conductivity of solid nanoparticles (aluminum) in a nanoporous solid matrix (diatomaceous earth) is examined to understand the effect of conductive fillers on the thermal properties of a porous material. We find that thermal conductivity is strongly dependent on load applied to prepare the mixture compacts, while porosity is influenced by the composition of the mixture. The addition of nanoparticles contributes to limited increases in thermal conductivity of the mixture by (1) increasing contact area between the mixture constituents and (2) reduction of porosity that leads to enhanced solid–gas coupling contribution. Thermal conductivity increases exponentially with external gas pressures due to the coupling effect between the solid particles and the entrapped air. - Highlights: • Thermal conductivity k of DE/AlNP mixture is more dependent on compaction than on Al concentration. • Nanoparticles affect k of DE by increase in solid contact area rather than by its effect on porosity. • When air content in mixture rises, k increases with gas pressures due to solid–gas coupling effect.

  10. Thermal Performance Benchmarking: Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States). Transportation and Hydrogen Systems Center

    2017-10-19

    In FY16, the thermal performance of the 2014 Honda Accord Hybrid power electronics thermal management systems were benchmarked. Both experiments and numerical simulation were utilized to thoroughly study the thermal resistances and temperature distribution in the power module. Experimental results obtained from the water-ethylene glycol tests provided the junction-to-liquid thermal resistance. The finite element analysis (FEA) and computational fluid dynamics (CFD) models were found to yield a good match with experimental results. Both experimental and modeling results demonstrate that the passive stack is the dominant thermal resistance for both the motor and power electronics systems. The 2014 Accord power electronics systems yield steady-state thermal resistance values around 42- 50 mm to the 2nd power K/W, depending on the flow rates. At a typical flow rate of 10 liters per minute, the thermal resistance of the Accord system was found to be about 44 percent lower than that of the 2012 Nissan LEAF system that was benchmarked in FY15. The main reason for the difference is that the Accord power module used a metalized-ceramic substrate and eliminated the thermal interface material layers. FEA models were developed to study the transient performance of 2012 Nissan LEAF, 2014 Accord, and two other systems that feature conventional power module designs. The simulation results indicate that the 2012 LEAF power module has lowest thermal impedance at a time scale less than one second. This is probably due to moving low thermally conductive materials further away from the heat source and enhancing the heat spreading effect from the copper-molybdenum plate close to the insulated gate bipolar transistors. When approaching steady state, the Honda system shows lower thermal impedance. Measurement results of the thermal resistance of the 2015 BMW i3 power electronic system indicate that the i3 insulated gate bipolar transistor module has significantly lower junction

  11. Thermal decomposition of illite

    Directory of Open Access Journals (Sweden)

    Araújo José Humberto de

    2004-01-01

    Full Text Available The effect of heat treatment on illite in air at temperatures ranging from 750 to 1150 °C was studied using the Mössbauer effect in 57Fe. The dependence of the Mössbauer parameters and relative percentage of the radiation absorption area was measured as a function of the firing temperature. The onset of thermal structural decomposition occurred at 800 °C. With rising temperature, the formation of hematite (Fe2O3 increased at the expense of the silicate mineral.

  12. Limits of Lubrication in

    DEFF Research Database (Denmark)

    Olsson, David Dam

    using plain mineral oil is possible without any lubricant breakdown. In deep drawing, 2mm stainless steel blanks can be drawn to drawing ratio of DR=2.0 over a die entry radius of rd=3mm again using a plain mineral oil containing no additives. In stretch forming, friction is reduced considerably...... of temperature and contact pressure. The numerical models have been calibrated regarding friction and thermal contact resistance based on experimental results from actual testing conditions. It has been found that predictions of limits of lubrication are possible by numerical means and that the FE...... based on analysis of the appearing backstroke force, which is very sensitive to tribological changes in the punch/workpiece interface, hence to lubricant breakdown. Fundamental studies of pick-up development in punching and blanking show that cold-welding of workpiece particles initially start...

  13. Enabling fast charging - Battery thermal considerations

    Science.gov (United States)

    Keyser, Matthew; Pesaran, Ahmad; Li, Qibo; Santhanagopalan, Shriram; Smith, Kandler; Wood, Eric; Ahmed, Shabbir; Bloom, Ira; Dufek, Eric; Shirk, Matthew; Meintz, Andrew; Kreuzer, Cory; Michelbacher, Christopher; Burnham, Andrew; Stephens, Thomas; Francfort, James; Carlson, Barney; Zhang, Jiucai; Vijayagopal, Ram; Hardy, Keith; Dias, Fernando; Mohanpurkar, Manish; Scoffield, Don; Jansen, Andrew N.; Tanim, Tanvir; Markel, Anthony

    2017-11-01

    Battery thermal barriers are reviewed with regards to extreme fast charging. Present-day thermal management systems for battery electric vehicles are inadequate in limiting the maximum temperature rise of the battery during extreme fast charging. If the battery thermal management system is not designed correctly, the temperature of the cells could reach abuse temperatures and potentially send the cells into thermal runaway. Furthermore, the cell and battery interconnect design needs to be improved to meet the lifetime expectations of the consumer. Each of these aspects is explored and addressed as well as outlining where the heat is generated in a cell, the efficiencies of power and energy cells, and what type of battery thermal management solutions are available in today's market. Thermal management is not a limiting condition with regard to extreme fast charging, but many factors need to be addressed especially for future high specific energy density cells to meet U.S. Department of Energy cost and volume goals.

  14. Modeling of Temperature-Dependent Noise in Silicon Nanowire FETs including Self-Heating Effects

    Directory of Open Access Journals (Sweden)

    P. Anandan

    2014-01-01

    Full Text Available Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resistance shows significant improvement as the channel length decreases. The effects of thermal noise including self-heating of the device are explored. Moreover, significant reduction in noise with respect to channel thermal resistance, gate length, and biasing is analyzed.

  15. Thermal instability in the interstellar medium

    Directory of Open Access Journals (Sweden)

    J. Ghanbari

    2000-06-01

    Full Text Available   This study demonstrates how thermal structures in the interstellar medium can emerge as a result of thermal instability. For a two-dimensional case, the steady state thermal structures was investigeted and it was shown that a large class of solutions exist. For a one –dimensional case the conductivity was found to be negligible. The effects of to cal cooling on the thermal instability were explored in some depth. In this case analytical results for time-dependent cooling function were presented, too. We studied nonlinear wave phenomena in thermal fluid systems, with a particular emphasis on presenting analytical results. When conductivity is proportional to temperature, the beliavior of thermal waves is soliton like. For slow thermal waves, approximate analytical results were presented. Extensions of this work are discussed briefly, together with possible astrophysical applications.

  16. A Unique Electrical Thermal Stimulation System Comparable to Moxibustion of Subcutaneous Tissue

    Directory of Open Access Journals (Sweden)

    Hyoun-Seok Myoung

    2014-01-01

    Full Text Available Moxibustion strengthens immunity and it is an effective treatment modality, but, depending on the material quantity, shape, and composition, the thermal strength and intensity can be difficult to control, which may cause pain or epidermal burns. To overcome