bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation of the global electric circuit and Ionospheric potential in a general circulation model
Authors: Mareev E. A. , Volodin E. M. 
Published: December 2014

AbstractA general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modeling the global electric circuit short‐time variability and long‐term evolution. The ionospheric potential parameterization is proposed which takes into account quasi‐stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The diurnal, seasonal, and interannual variations of the ionospheric potential (IP) are modeled and compared with available data. Numerical simulations suggest that the IP decreases in the mean with the global warming due to increasing greenhouse gas emission (by about 10% during the 21st century if the Representative Concentration Pathway 8.5 Wm−2 scenario is assumed). At the same time the lightning flash rate increases with global warming by about 5 fl/s per degree. Interannual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature in the Pacific Ocean (El Niño area).
Return stroke speed of cloud‐to‐ground lightning estimated from elve hole radii
Authors: Blaes P. R. , Marshall R. A. , Inan U. S. 
Published: December 2014

AbstractWe present the first measurements of the lightning return stroke speed that directly relate to the current return stroke, as opposed to its optical manifestation. The shape of elves is determined by the electromagnetic pulse (EMP) radiation pattern at D region altitudes, which is in turn controlled by the geometry and current propagation properties of the return stroke channel. In particular, numerical simulation of the EMP‐ionosphere interaction shows a strong relationship between the elve “hole” radius and the current return stroke speed. The hole radii are measured from a data set of 55 elves observed with the PIPER photometer. Using these radii observations in conjunction with numerical simulations of the EMP, we perform Bayesian inference to estimate the distribution of return stroke speeds. The results show a maximum a posteriori probability return stroke speed estimate of 0.64c for elve producing lightning.
Mars Express radio‐occultation data: A novel analysis approach
Authors: Grandin M. , Blelly P.‐L. , Witasse O. , Marchaudon A. 
Published: December 2014

AbstractThe Mars Express Radio Science (MaRS) experiment on board Mars Express has been providing radio‐occultation data since early 2004. The analysis method currently used to retrieve neutral atmosphere and ionosphere profiles is based on the resolution of a complex inverse problem. The solution to such a problem is obtained under strong assumptions on the atmosphere and the ionosphere and with some limitations. Here we developed a novel method for radio‐occultation data analysis based on a direct approach which overcomes some of the difficulties related to the standard inversion. This new method is based on a numerical model of the atmosphere and the ionosphere of Mars computing the propagation of the radio waves from the spacecraft to the receiver on Earth. The main interest of such an approach lies in the intrinsic and coherent coupling between the neutral part and the ionized part of the planetary environment, which gives physical constrains on the retrieved profiles. We have applied this new method to radio occultation experiments performed by MaRS, and we present the results obtained in two different occultation configurations. We discuss the differences which emerge from the standard analysis and the gain that such a method can give to the analysis of planetary environments.
Effects of a low‐viscosity lower crust on topography and gravity at convergent mountain belts during gravitational instability of mantle lithosphere
Authors: Molnar Peter , Houseman Gregory A. 
Published: December 2014

AbstractWe examine the gravitational stability of a stratified structure consisting of a low‐density crust through which viscosity decreases exponentially, over a denser mantle lithosphere of constant viscosity, which in turn overlies an inviscid, slightly less dense layer like the asthenosphere. The most important aspect of the viscosity structure is the contrast in viscosity at the Moho. Surface uplift above a mantle downwelling is greatest when the viscosity contrast at the Moho is negligible. The surface is depressed when the viscosity of the lowermost crust is much greater than mantle viscosity. For a wide range of viscosity structures, calculated gravity anomalies and in particular admittances (ratios of the Fourier transform of gravity to that of topography) produced by Rayleigh‐Taylor instability differ markedly from those observed across convergent mountain belts. In particular, whereas values of calculated admittance are negative, or very small, observed admittances are consistently positive. Thus, if downwelling of mantle lithosphere directly beneath mountain ranges plays an important role in the construction of mountain belts, it cannot be the main process that induces crustal thickening.
Beyond‐laboratory‐scale prediction for channeling flows through subsurface rock fractures with heterogeneous aperture distributions revealed by laboratory evaluation
Authors: Ishibashi Takuya , Watanabe Noriaki , Hirano Nobuo , Okamoto Atsushi , Tsuchiya Noriyoshi 
Published: December 2014

AbstractThe present study evaluates aperture distributions and fluid flow characteristics for variously sized laboratory‐scale granite fractures under confining stress. As a significant result of the laboratory investigation, the contact area in fracture plane was found to be virtually independent of scale. By combining this characteristic with the self‐affine fractal nature of fracture surfaces, a novel method for predicting fracture aperture distributions beyond laboratory scale is developed. Validity of this method is revealed through reproduction of the results of laboratory investigation and the maximum aperture‐fracture length relations, which are reported in the literature, for natural fractures. The present study finally predicts conceivable scale dependencies of fluid flows through joints (fractures without shear displacement) and faults (fractures with shear displacement). Both joint and fault aperture distributions are characterized by a scale‐independent contact area, a scale‐dependent geometric mean, and a scale‐independent geometric standard deviation of aperture. The contact areas for joints and faults are approximately 60% and 40%. Changes in the geometric means of joint and fault apertures (µm), em, joint and em, fault, with fracture length (m), l, are approximated by em, joint = 1 × 102 l0.1 and em, fault = 1 × 103 l0.7, whereas the geometric standard deviations of both joint and fault apertures are approximately 3. Fluid flows through both joints and faults are characterized by formations of preferential flow paths (i.e., channeling flows) with scale‐independent flow areas of approximately 10%, whereas the joint and fault permeabilities (m2), kjoint and kfault, are scale dependent and are approximated as kjoint = 1 × 10−12 l0.2 and kfault = 1 × 10−8 l1.1.
Synthetic earthquake catalogs simulating seismic activity in the Corinth Gulf, Greece, fault system
Authors: Console Rodolfo , Carluccio Roberto , Papadimitriou Eleftheria , Karakostas Vassilis 
Published: December 2014

AbstractThe characteristic earthquake hypothesis is the basis of time‐dependent modeling of earthquake recurrence on major faults. However, the characteristic earthquake hypothesis is not strongly supported by observational data. Few fault segments have long historical or paleoseismic records of individually dated ruptures, and when data and parameter uncertainties are allowed for, the form of the recurrence distribution is difficult to establish. This is the case, for instance, of the Corinth Gulf Fault System (CGFS), for which documents about strong earthquakes exist for at least 2000 years, although they can be considered complete forM ≥ 6.0 only for the latest 300 years, during which only few characteristic earthquakes are reported for individual fault segments. The use of a physics‐based earthquake simulator has allowed the production of catalogs lasting 100,000 years and containing more than 500,000 events of magnitudes ≥ 4.0. The main features of our simulation algorithm are (1) an average slip rate released by earthquakes for every single segment in the investigated fault system, (2) heuristic procedures for rupture growth and stop, leading to a self‐organized earthquake magnitude distribution, (3) the interaction between earthquake sources, and (4) the effect of minor earthquakes in redistributing stress. The application of our simulation algorithm to the CGFS has shown realistic features in time, space, and magnitude behavior of the seismicity. These features include long‐term periodicity of strong earthquakes, short‐term clustering of both strong and smaller events, and a realistic earthquake magnitude distribution departing from the Gutenberg‐Richter distribution in the higher‐magnitude range.
Second‐order structure function analysis of scatterometer winds over the Tropical Pacific
Authors: King Gregory P. , Vogelzang Jur , Stoffelen Ad 
Published: December 2014

AbstractKolmogorov second‐order structure functions are used to quantify and compare the small‐scale information contained in near‐surface ocean wind products derived from measurements by ASCAT on MetOp‐A and SeaWinds on QuikSCAT. Two ASCAT and three SeaWinds products are compared in nine regions (classified as rainy or dry) in the tropical Pacific between 10°S and 10°N and 140° and 260°E for the period November 2008 to October 2009. Monthly and regionally averaged longitudinal and transverse structure functions are calculated using along‐track samples. To ease the analysis, the following quantities were estimated for the scale range 50 to 300 km and used to intercompare the wind products: (i) structure function slopes, (ii) turbulent kinetic energies (
), and (iii) vorticity‐to‐divergence ratios. All wind products are in good qualitative agreement, but also have important differences. Structure function slopes and
differ per wind product, but also show a common variation over time and space. Independent of wind product, longitudinal slopes decrease when sea surface temperature exceeds the threshold for onset of deep convection (about 28°C). In rainy areas and in dry regions during rainy periods, ASCAT has larger divergent
than SeaWinds, while SeaWinds has larger vortical
than ASCAT. Differences between SeaWinds and ASCAT vortical
and vorticity‐to‐divergence ratios for the convectively active months of each region are large.
Thermal variations in the South China Sea associated with the eastern and central Pacific El Niño events and their mechanisms
Authors: Liu Qin‐Yan , Wang Dongxiao , Wang Xin , Shu Yeqiang , Xie Qiang , Chen Ju 
Published: December 2014

AbstractIn this study, we investigate the interannual variability of the sea surface temperature (SST) in the South China Sea (SCS) associated with two types of El Niño, namely, the eastern Pacific (EP) El Niño and the central Pacific (CP) El Niño. First, double warm peaks can occur during both types of El Niño events in the SCS. However, the strong warm basin mode can only develop in the EP El Niño, while the warm semibasin mode exists during the CP El Niño. Associated with an anomalous positive (negative) net surface heat flux in the EP (CP) El Niño, along with a shallower thermocline with weaker (stronger) northeasterly wind anomalies, the SST anomalies become warmer (cooler) in the developing autumn. Over the background of cooling SST in autumn of CP El Niño, therefore, only a weak warming can occur in the subsequent years, which is limited in the western boundary area under the forcing of warm ocean advection. Second, the SST oscillation periods are different in these two types of El Niño. The SST evolution in the EP El Niño is negative‐positive with a quasi‐biennial oscillation, but that in the CP El Niño is positive‐negative‐positive‐negative with an annual oscillation. It seems that the double cooling in the CP El Niño is phase‐locked to the late autumn season.
The effect of stratospheric sulfur from Mount Pinatubo on tropospheric oxidizing capacity and methane
Authors: Bândă Narcisa , Krol Maarten , van Noije Twan , van Weele Michiel , Williams Jason E. , Sager Philippe Le , Niemeier Ulrike , Thomason Larry , Röckmann Thomas 
Published: December 2014

AbstractThe eruption of Mount Pinatubo in 1991 injected a large amount of SO2 into the stratosphere, which formed sulfate aerosols. Increased scattering and absorption of UV radiation by the enhanced stratospheric SO2 and aerosols decreased the amount of UV radiation reaching the troposphere, causing changes in tropospheric photochemistry. These changes affected the oxidizing capacity of the atmosphere and the removal rate of CH4 in the years following the eruption. We use the three‐dimensional chemistry transport model TM5 coupled to the aerosol microphysics module M7 to simulate the evolution of SO2 and sulfate aerosols from the Pinatubo eruption. Their effect on tropospheric photolysis frequencies and concentrations of OH and CH4 is quantified for the first time. We find that UV attenuation by stratospheric sulfur decreased the photolysis frequencies of both ozone and NO2 by about 2% globally, decreasing global OH concentrations by a similar amount in the first 2 years after the eruption. SO2 absorption mainly affects OH primary production by ozone photolysis, while aerosol scattering also alters OH recycling. The effect of stratospheric sulfur on global OH and CH4 is dominated by the effect of aerosol extinction, while SO2 absorption contributes by 12.5% to the overall effect in the first year after the eruption. The reduction in OH concentrations causes an increase in the CH4 growth rate of 4 and 2 ppb/yr in the first and second years after the eruption, respectively, contributing 11 Tg to the 27 Tg observed CH4 burden change in late 1991 and early 1992.
A review of volume‐area scaling of glaciers
Authors: Bahr David B. , Pfeffer W. Tad , Kaser Georg 
Published: December 2014

AbstractVolume‐area power law scaling, one of a set of analytical scaling techniques based on principals of dimensional analysis, has become an increasingly important and widely used method for estimating the future response of the world's glaciers and ice caps to environmental change. Over 60 papers since 1988 have been published in the glaciological and environmental change literature containing applications of volume‐area scaling, mostly for the purpose of estimating total global glacier and ice cap volume and modeling future contributions to sea level rise from glaciers and ice caps. The application of the theory is not entirely straightforward, however, and many of the recently published results contain analyses that are in conflict with the theory as originally described by Bahr et al. (1997). In this review we describe the general theory of scaling for glaciers in full three‐dimensional detail without simplifications, including an improved derivation of both the volume‐area scaling exponent γ and a new derivation of the multiplicative scaling parameter c. We discuss some common misconceptions of the theory, presenting examples of both appropriate and inappropriate applications. We also discuss potential future developments in power law scaling beyond its present uses, the relationship between power law scaling and other modeling approaches, and some of the advantages and limitations of scaling techniques.
Nowcast model for low‐energy electrons in the inner magnetosphere
Authors: Ganushkina N. Yu. , Amariutei O. A. , Welling D. , Heynderickx D. 
Published: December 2014

AbstractWe present the nowcast model for low‐energy (<200 keV) electrons in the inner magnetosphere, which is the version of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) for electrons. Low‐energy electron fluxes are very important to specify when hazardous satellite surface‐charging phenomena are considered. The presented model provides the low‐energy electron flux at all L shells and at all satellite orbits, when necessary. The model is driven by the real‐time solar wind and interplanetary magnetic field (IMF) parameters with 1 h time shift for propagation to the Earth's magnetopause and by the real time Dst index. Real‐time geostationary GOES 13 or GOES 15 (whenever each is available) data on electron fluxes in three energies, such as 40 keV, 75 keV, and 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides quite reasonable agreement with the data; the basic level of the observed fluxes is reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. The normalized root‐mean‐square deviation is found to range from 0.015 to 0.0324. Though these metrics are buoyed by large standard deviations, owing to the dynamic nature of the fluxes, they demonstrate that IMPTAM, on average, predicts the observed fluxes satisfactorily. The computed binary event tables for predicting high flux values within each 1 h window reveal reasonable hit rates being 0.660–0.318 for flux thresholds of 5 ·104–2 ·105 cm−2 s−1 sr−1 keV−1 for 40 keV electrons, 0.739–0.367 for flux thresholds of 3 ·104–1 ·105 cm−2 s−1 sr−1 keV−1 for 75 keV electrons, and 0.485–0.438 for flux thresholds of 3 ·103–3.5 ·103 cm−2 s−1 sr−1 keV−1 for 150 keV electrons but rather small Heidke Skill Scores (0.17 and below). This is the first attempt to model low‐energy electrons in real time at 10 min resolution. The output of this model can serve as an input of electron seed population for real‐time higher‐energy radiation belt modeling.
Agricultural virtual water flows within the United States
Authors: Dang Qian , Lin Xiaowen , Konar Megan 
Published: December 2014

AbstractTrade plays an increasingly important role in the global food system, which is projected to be strained by population growth, economic development, and climate change. For this reason, there has been a surge of interest in the water resources embodied in international trade, referred to as “global virtual water trade.” In this paper, we present a comprehensive assessment of virtual water flows within the United States (U.S.), a country with global importance as a major agricultural producer and trade power. This is the first study of domestic virtual water flows based upon intranational food transfer empirical data and it provides insight into how the properties of virtual water transfers vary across scales. We find that the volume of virtual water flows within the U.S. is equivalent to 51% of international flows, which is slightly higher than the U.S. food value and mass shares, due to the fact that water‐intensive meat commodities comprise a much larger fraction of food transfers within the U.S.. The U.S. virtual water flow network is more social, homogeneous, and equitable than the global virtual water trade network, although it is still not perfectly equitable. Importantly, a core group of U.S. States is central to the network structure, indicating that both domestic and international trade may be vulnerable to disruptive climate or economic shocks in these U.S. States.
History of Clinical Medicine
Authors: Weatherall MW , Weatherall DJ 
Published: December 2014

Abstract

The history of clinical medicine reflects both the complex nature of the relationship between doctors and patients, and the slow evolution of knowledge in natural philosophy and, more recently, the biomedical sciences. This article provides an overview of these issues as they have developed over the last 2500 years, specifically focussing on the application of science and natural philosophy to the control and management of human disease. Despite the expansion of, and remarkable advances in, the biomedical sciences during the past two centuries, the multilayered complexities of disease processes and the ever changing environments of sick people ensure that clinical medicine still remains very much a mix of applied science and the art of healing.

Key Concepts:

The history of clinical medicine reflects the slow development of the science and art of medical care set against the background of changes in political, cultural, environmental and economic factors.

The Greco‐Roman concept that health reflects the balance of the four humours lasted for two millennia.

Disease was believed to reflect an imbalance of the humours.

During the Renaissance the humoural concept of disease was discarded and the fields of anatomy, chemistry and surgery began to influence the development of medical practice.

During the seventeenth century there were major advances in the understanding of human physiology and the importance of clinical practice at the bedside was emphasised.

During the eighteenth and nineteenth centuries the scientific basis of clinical care and the beginnings of statistical approaches to its applications continued to develop.

During the twentieth and early years of the twenty‐first centuries there were dramatic advances in every aspect of scientific medicine, culminating in the description of disease at the molecular level, and accompanied by changes in the patterns of provision of health care in many countries.
Racemic DNA Crystallography
Authors: Mandal Pradeep K. , Collie Gavin W. , Kauffmann Brice , Huc Ivan 
Published: December 2014

AbstractRacemates increase the chances of crystallization by allowing molecular contacts to be formed in a greater number of ways. With the advent of protein synthesis, the production of protein racemates and racemic‐protein crystallography are now possible. Curiously, racemic DNA crystallography had not been investigated despite the commercial availability of L‐ and D‐deoxyribo‐oligonucleotides. Here, we report a study into racemic DNA crystallography showing the strong propensity of racemic DNA mixtures to form racemic crystals. We describe racemic crystal structures of various DNA sequences and folded conformations, including duplexes, quadruplexes, and a four‐way junction, showing that the advantages of racemic crystallography should extend to DNA.
Stiffness‐Dependent In Vitro Uptake and Lysosomal Acidification of Colloidal Particles
Authors: Hartmann Raimo , Weidenbach Marcel , Neubauer Martin , Fery Andreas , Parak Wolfgang J. 
Published: December 2014

AbstractThe physico‐chemical properties of colloidal particles determine their uptake into cells. For a series of microparticles only one parameter, the mechanical stiffness, was varied, whereas other parameters such as size, shape, and charge were kept constant. The uptake was monitored in situ by analyzing individual particle trajectories including the progress of endocytosis, derived from local pH measurements around each particle. Evidence is presented that soft particles with low stiffness are transported faster to lysosomes than stiffer ones.
Short, Enantioselective Total Synthesis of Chatancin
Authors: Zhao Yu‐Ming , Maimone Thomas J. 
Published: December 2014

AbstractAn enantioselective total synthesis of the polycyclic diterpene (+)‐chatancin, a potent PAF antagonist, is reported. Proceeding in seven steps from dihydrofarnesal, this synthetic route was designed to circumvent macrocyclization‐based strategies to complex, cyclized cembranoids. The described synthesis requires only six chromatographic purifications, is high yielding, and avoids protecting‐group manipulations. An X‐ray crystal structure of this fragile marine natural product was obtained.