380 research outputs found

    How to identify groundwater-caused thermal anomalies in lakes based on multi-temporal satellite data in semi-arid regions

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    The deduction by conventional means of qualitative and quantitative information about groundwater discharge into lakes is complicated. Nevertheless, at least for semi-arid regions with limited surface water availability, this information is crucial to ensure future water availability for drinking and irrigation purposes. <br><br> Overcoming this lack of discharge information, we present a satellite-based multi-temporal sea-surface-temperature (SST) approach. It exploits the occurrence of thermal anomalies to outline groundwater discharge locations using the example of the Dead Sea. Based on a set of 19 Landsat Enhanced Thematic Mapper (ETM+) images 6.2 (high gain), recorded between 2000 and 2002, we developed a novel approach which includes (i) an objective exclusion of surface-runoff-influenced data which would otherwise lead to erroneous results and (ii) a temporal SST variability analysis based on six statistical measures amplifying thermal anomalies caused by groundwater. <br><br> After excluding data influenced by surface runoff, we concluded that spatial anomaly patterns of the standard deviation and range of the SST data series spatially fit best to in situ observed discharge locations and, hence, are most suitable for detecting groundwater discharge sites

    Transition State Spectroscopy of the Photoinduced Ca + CH3F Reaction. 2. Experimental and Ab Initio Studies of the Free Ca***FCH3 Complex

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    International audienceThe Ca* + CH3F CaF* + CH3 reaction was photoinduced in 1:1 Ca***CH3F complexes formed in a supersonic expansion. The transition state of the reaction was explored by monitoring the electronically excited product, CaF, while scanning the laser that turns on the reaction. Moreover, the electronic structure of the Ca***FCH3 system was studied using ab initio methods by associating a pseudopotential description of the [Ca2+] and [F7+] cores, a core polarization operator on calcium, an extensive Gaussian basis and a treatment of the electronic problem at the CCSD(T) (ground state) and RSPT2 (excited states) level. In this contribution we present experimental results for the free complex and a comparison with the results of a previous experiment where the Ca***CH3F complexes are deposited at the surface of large argon clusters. The ab initio calculations allowed an interpretation of the experimental data in terms of two reaction mechanisms, one involving a partial charge transfer state, the other involving the excitation of the C-F stretch in the CH3F moiety prior to charge transfer

    A new view of electrochemistry at highly oriented pyrolytic graphite

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    Major new insights on electrochemical processes at graphite electrodes are reported, following extensive investigations of two of the most studied redox couples, Fe(CN)64–/3– and Ru(NH3)63+/2+. Experiments have been carried out on five different grades of highly oriented pyrolytic graphite (HOPG) that vary in step-edge height and surface coverage. Significantly, the same electrochemical characteristic is observed on all surfaces, independent of surface quality: initial cyclic voltammetry (CV) is close to reversible on freshly cleaved surfaces (>400 measurements for Fe(CN)64–/3– and >100 for Ru(NH3)63+/2+), in marked contrast to previous studies that have found very slow electron transfer (ET) kinetics, with an interpretation that ET only occurs at step edges. Significantly, high spatial resolution electrochemical imaging with scanning electrochemical cell microscopy, on the highest quality mechanically cleaved HOPG, demonstrates definitively that the pristine basal surface supports fast ET, and that ET is not confined to step edges. However, the history of the HOPG surface strongly influences the electrochemical behavior. Thus, Fe(CN)64–/3– shows markedly diminished ET kinetics with either extended exposure of the HOPG surface to the ambient environment or repeated CV measurements. In situ atomic force microscopy (AFM) reveals that the deterioration in apparent ET kinetics is coupled with the deposition of material on the HOPG electrode, while conducting-AFM highlights that, after cleaving, the local surface conductivity of HOPG deteriorates significantly with time. These observations and new insights are not only important for graphite, but have significant implications for electrochemistry at related carbon materials such as graphene and carbon nanotubes

    Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

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    Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh

    Causal Network Accounts Of Ill-being: Depression & Digital Well-being

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    Depression is a common and devastating instance of ill-being which deserves an account. Moreover, the ill-being of depression is impacted by digital technology: some uses of digital technology increase such ill-being while other uses of digital technology increase well-being. So a good account of ill-being would explicate the antecedents of depressive symptoms and their relief, digitally and otherwise. This paper borrows a causal network account of well-being and applies it to ill-being, particularly depression. Causal networks are found to provide a principled, coherent, intuitively plausible, and empirically adequate account of cases of depression in every-day and digital contexts. Causal network accounts of ill-being also offer philosophical, scientific, and practical utility. Insofar as other accounts of ill-being cannot offer these advantages, we should prefer causal network accounts of ill-being

    Channel sounding and indoor radio channel characteristics in the W-band

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    This work presents directional radio channel measurements in the W-band using a commercial versatile channel sounder based on a vector network analyzer (VNA), capable of measuring scattering parameters from 75 to 500 GHz with frequency converters. The commercial setup has been modified by increasing the distance for one of the converters using precision coaxial cables and avoiding the use of amplifiers. Firstly, initial distance-dependent single-input single-output (SISO) measurements of indoor radio channels are presented to assess the validity of the setup in the 75 110 GHz frequency band with highly directive horn antennas. Then, single-input multiple-output (SIMO) radio channels were measured at 94 GHz using one directional and one omnidirectional antenna mounted on two positioners. Initial channel characterization is presented comprising root mean square (rms) delay spread, rms angular spread, K-factor, and path loss in an indoor environment at 94 GHz.This work was supported by MINECO, Spain (TEC2013-47360-C3-2-P TEC2013-47360-C3-3-P) and by European FEDER funds.Martínez Inglés, M.; Gaillot, D.; Pascual-García, J.; Molina-García-Pardo, JM.; Rodriguez Rodriguez, JV.; Rubio Arjona, L.; Juan Llacer, L. (2016). Channel sounding and indoor radio channel characteristics in the W-band. EURASIP Journal on Wireless Communications and Networking. 30:1-8. doi:10.1186/s13638-016-0530-7S1830D Zico, Ultra-wideband and 60 GHz communications for biomedical applications. Springer. http://link.springer.com/book/10.1007%2F978-1-4614-8896-5 .L Jofre, J Romeu, S Capdevila, J Abril, E Nova, M Alonso, The “challenging” world of Terahertz radiation and imaging. Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP), 2011, pp. 3470–3475M Kawase, “Non-destructive evaluation method of pharmaceutical tablet by terahertz-time-domain spectroscopy: application to sound-alike medicines”, J. Infrared Millimeter Terahertz Waves, 34(9), 566–571KD Anderson, 94 GHz propagation in the evaporation duct. IEEE Trans. Antennas Propag. 38(5), 746–753 (1990)K Aydin, Y-M Lure, Millimeter wave scattering and propagation in rain: a computational study at 94 and 140 GHz for oblate spheroidal and spherical raindrops. IEEE Trans. Geosci. Remote Sens. 29(1), 593–601 (1991)C Gloaguen, An experiment for propagation studies at 94 GHz. Eighth Int. Conf. Antennas Propagation 1, 406–409 (1993)A Kajiwara, “Indoor propagation measurements at 94 GHz,” personal, indoor and mobile radio communications, 1995. Sixth IEEE Int. Symp PIMRC’95. Wireless Merging Inf. Superhighway 3, 1026 (1995)J Helminger, J Detlefsen, H Groll, Propagation properties of an indoor-channel at 94 GHz. Int. Conf. Microw Millimeter Wave Technol.Proc 98, 9–14 (1998)R Piesiewicz, R Geise, M Jacob, J Jemai, T Kurner, “Indoor channel measurements of point-to-point ultra broadband short range links between 75 GHz and 110 GHz”, in International Symposium Antennas and Propagation Society, 2008, pp. 1–4A Brizzi, A Pellegrini, Y Hao, “Experimental characterization of the propagation on the human torso at W band”, in Radio Science Meeting (Joint with AP-S Symposium), USNC-URSI, 2013, p. 39K Haneda, J Järveläinen, A Karttunen, M Kyro, J Putkonen, Indoor short-range radio propagation measurements At 60 and 70 GHz, in EuCAP 2014, The Hague, The Netherlands, 2014, pp. 1–4S Promwong, J Takada, Free space link budget estimation scheme for ultra wideband impulse radio with imperfect antennas. IEICE Electronics Express 1(7), 188–192 (2004)NL Johnson, S Kotz, N Balakrishnan, Continuous univariate distributions, vol. 1 (Wiley-Interscience, Hoboken, 1993)A Richter, Estimation of radio channel parameters: models and algorithms (Dr.-Ing. dissertation, TU Ilmenau, Ilmenau, Germany, 2005

    PRegnancy Outcomes after a Maternity Intervention for Stressful EmotionS (PROMISES): study protocol for a randomised controlled trial

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    <p>Abstract</p> <p>Background</p> <p>There is ample evidence from observational prospective studies that maternal depression or anxiety during pregnancy is a risk factor for adverse psychosocial outcomes in the offspring. However, to date no previous study has demonstrated that treatment of depressive or anxious symptoms in pregnancy actually could prevent psychosocial problems in children. Preventing psychosocial problems in children will eventually bring down the huge public health burden of mental disease. The main objective of this study is to assess the effects of cognitive behavioural therapy in pregnant women with symptoms of anxiety or depression on the child's development as well as behavioural and emotional problems. In addition, we aim to study its effects on the child's development, maternal mental health, and neonatal outcomes, as well as the cost-effectiveness of cognitive behavioural therapy relative to usual care.</p> <p>Methods/design</p> <p>We will include 300 women with at least moderate levels of anxiety or depression at the end of the first trimester of pregnancy. By including 300 women we will be able to demonstrate effect sizes of 0.35 or over on the total problems scale of the child behavioural checklist 1.5-5 with alpha 5% and power (1-beta) 80%.</p> <p>Women in the intervention arm are offered 10-14 individual cognitive behavioural therapy sessions, 6-10 sessions during pregnancy and 4-8 sessions after delivery (once a week). Women in the control group receive care as usual.</p> <p>Primary outcome is behavioural/emotional problems at 1.5 years of age as assessed by the total problems scale of the child behaviour checklist 1.5 - 5 years.</p> <p>Secondary outcomes will be mental, psychomotor and behavioural development of the child at age 18 months according to the Bayley scales, maternal anxiety and depression during pregnancy and postpartum, and neonatal outcomes such as birth weight, gestational age and Apgar score, health care consumption and general health status (economic evaluation).</p> <p>Trial Registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2242">NTR2242</a></p
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