bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separator reconnection with antiparallel/component features observed in magnetotail plasmas
Authors: Guo Ruilong , Pu Zuyin , Xiao Chijie , Wang Xiaogang , Fu Suiyan , Xie Lun , Zong Qiugang , He Jiansen , Yao Zhonghua , Zhong Jun , Li Jinxing 
Published: October 2013

AbstractMagnetic reconnection (MR), a fundamental process in space plasmas that changes magnetic topology and converts magnetic energy into kinetic and thermal energies, is an ultimate driver of space weather. There exist two models of MR in the literatures, antiparallel and component, associated with intensive studies of their generation and applications. In this paper, we report an MR event observed by Cluster constellation in the geomagnetotail where both types of MR were detected. By reconstructing the three‐dimensional (3‐D) MR configuration, we find that a pair of A‐B nulls existed in both types of MR cases with two fan surfaces intersecting each other to form a separator line connecting the nulls. A weak or sizable magnetic field exists along the separator in the antiparallel or component case, respectively. In the latter case, field strength is finite away from the two nulls and vanishes close to the nulls. Therefore, at least in the two cases observed, both antiparallel and component MR geometries are local presentation of the separator MR configuration. This result supports the expectation that 3‐D nulls often occur as a crucial element of MR at least in the magnetotail and separator MR may play an important role in dynamics and reconfiguration of magnetic field in 3‐D MR processes.
Downdip landward limit of Cascadia great earthquake rupture
Authors: Hyndman R. D. 
Published: October 2013

AbstractThis paper examines the constraints to the downdip landward limit of rupture for the Cascadia great earthquakes off western North America. This limit is a primary control for ground motion hazard at near‐coastal cities. The studies also provide information on the physical controls of subduction thrust rupture globally. The constraints are (1) “locked/transition” zones from geodetic deformation (GPS, repeated leveling, tide gauges); (2) rupture zone from paleoseismic coastal marsh subsidence, “paleogeodesy”; (3) temperature on the thrust for the seismic‐aseismic transition; (4) change in thrust seismic reflection character downdip from thin seismic to thick ductile; (5) fore‐arc mantle corner aseismic serpentinite and talc overlying the thrust; (6) updip limit of episodic tremor and slip (ETS) slow slip; (7) rupture area associations with shelf‐slope basins; (8) depth limit for small events on the thrust; and (9) landward limit of earthquakes on the Nootka transform fault zone. The most reliable constraints for the limit of large rupture displacement, >10 m, are generally just offshore in agreement with thermal control for this hot subduction zone, but well‐offshore central Oregon and near the coast of northern Washington. The limit for 1–2 m rupture that can still provide strong shaking is less well estimated 25–50 km farther landward. The fore‐arc mantle corner and the updip extent of ETS slow slip are significantly landward from the other constraints. Surprisingly, there is a downdip gap between the best other estimates for the great earthquake rupture zone and the ETS slow slip. In this gap, plate convergence may occur as continuous slow creep.
Tropospheric SF6: Age of air from the Northern Hemisphere midlatitude surface
Authors: Waugh D. W. , Crotwell A. M. , Dlugokencky E. J. , Dutton G. S. , Elkins J. W. , Hall B. D. , Hintsa E. J. , Hurst D. F. , Montzka S. A. , Mondeel D. J. , Moore F. L. , Nance J. D. , Ray E. A. , Steenrod S. D. , Strahan S. E. , Sweeney C. 
Published: October 2013

AbstractObservations of SF6 are used to quantify the mean time since air was in (“mean age” from) the Northern Hemisphere (NH) midlatitude surface layer. The mean age is a fundamental property of tropospheric transport that can be used in theoretical studies and used to evaluate transport in comprehensive models. Comparisons of simulated SF6 and an idealized clock tracer confirm that the time lag between the SF6 mixing ratio at a given location and the NH midlatitude surface provides an accurate estimate of the mean age. The ages calculated from surface SF6 measurements show large meridional gradients in the tropics but weak gradients in the extratropics, with near‐zero ages at the surface north of 30°N and ages around 1.4 years south of 30°S. Aircraft measurements show weak vertical age gradients in the lower and middle troposphere, with only slight increases of age with height in the NH and slight decreases with height in the Southern Hemisphere. There are large seasonal variations in the age at tropical stations (annual amplitudes around 0.5–1.0 year), with younger ages during northern winter, but only weak seasonal variations at higher latitudes. The seasonality and interannual variations in the tropics and Southern Hemisphere are related to changes in locations of tropical convection. There is qualitative agreement, in both spatial and temporal variations, between the simulated ages and observations. The model ages tend to be older than observed, with differences of ~0.2 year in the Northern Hemisphere upper troposphere and throughout the Southern Hemisphere troposphere.
Characterizing sampling biases in the trace gas climatologies of the SPARC Data Initiative
Authors: Toohey M. , Hegglin M. I. , Tegtmeier S. , Anderson J. , Añel J. A. , Bourassa A. , Brohede S. , Degenstein D. , Froidevaux L. , Fuller R. , Funke B. , Gille J. , Jones A. , Kasai Y. , Krüger K. , Kyrölä E. , Neu J. L. , Rozanov A. , Smith L. , Urban J. , von Clarmann T. , Walker K. A. , Wang R. H. J. 
Published: October 2013

AbstractMonthly zonal mean climatologies of atmospheric measurements from satellite instruments can have biases due to the nonuniform sampling of the atmosphere by the instruments. We characterize potential sampling biases in stratospheric trace gas climatologies of the Stratospheric Processes and Their Role in Climate (SPARC) Data Initiative using chemical fields from a chemistry climate model simulation and sampling patterns from 16 satellite‐borne instruments. The exercise is performed for the long‐lived stratospheric trace gases O3 and H2O. Monthly sampling biases for O3 exceed 10% for many instruments in the high‐latitude stratosphere and in the upper troposphere/lower stratosphere, while annual mean sampling biases reach values of up to 20% in the same regions for some instruments. Sampling biases for H2O are generally smaller than for O3, although still notable in the upper troposphere/lower stratosphere and Southern Hemisphere high latitudes. The most important mechanism leading to monthly sampling bias is nonuniform temporal sampling, i.e., the fact that for many instruments, monthly means are produced from measurements which span less than the full month in question. Similarly, annual mean sampling biases are well explained by nonuniformity in the month‐to‐month sampling by different instruments. Nonuniform sampling in latitude and longitude are shown to also lead to nonnegligible sampling biases, which are most relevant for climatologies which are otherwise free of biases due to nonuniform temporal sampling.
Wave heating and Jeans escape in the Martian upper atmosphere
Authors: Walterscheid R. L. , Hickey M. P. , Schubert G. 
Published: October 2013

AbstractGusty flow over rough terrain is likely to be a significant source of fast gravity waves and acoustic waves in the atmosphere of Mars, as it is in Earth's atmosphere. Accordingly, we have used a numerical model to study the dissipation in the thermosphere and exosphere of Mars of upward‐propagating fast gravity waves and acoustic waves. Model simulations are performed for a range of wave periods and horizontal wavelengths. Wave amplitudes are constrained by the Mars Global Surveyor and Mars Odyssey aerobraking data, and gravity wave phase velocities are limited by occultation data. Dissipating gravity waves heat some regions of the thermosphere and cool others through the effects of sensible heat flux divergence, while acoustic waves mainly heat the Mars thermosphere. Heating rates can be on the order of several hundred Kelvin per day. The cycle‐integrated effects on the Jeans escape flux are also investigated and found to be on the order of background values and even greater and might be a significant source of loss of the Martian atmosphere to space.
Characterization of the spatial and temporal variability of surface water in the Soudan‐Sahel region of Africa
Authors: Kaptué Armel T. , Hanan Niall P. , Prihodko Lara 
Published: October 2013

AbstractWater is a precious resource since the lives and livelihoods of human societies depend on their ability to access this resource. This is particularly true in arid and semiarid regions like the Sahel where permanent surface waters are rare and hydrological solutions (e.g., accessing deep aquifers) are often not feasible. This work is devoted to the determination of the spatial and temporal variations of surface water extent at 250 m over 9 years (2003–2011) for the Soudan‐Sahel region using visible and infrared imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) from both Terra and Aqua platforms. The methodology is automatic and could be applied to other regions and sensors. We utilized a combination of two MODIS spectral indices: the Normalized Difference Vegetation Index and the Modified Normalized Difference Water Index. Accuracy assessments carried out on 743 lakes across 37 Landsat images selected in Sahelian Africa on the basis of a stratified sampling show that the new product is (i) reliably able to detect surface water bodies of approximately 50 ha and larger, (ii) improves on existing surface water body products, and (iii) can be used to monitor the seasonal distribution of surface water in semiarid regions.
Effect of nutrient enrichment on δ13CH4 and the methane production pathway in the Florida Everglades
Authors: Holmes M. Elizabeth , Chanton Jeffrey P. , Bae Hee‐Sung , Ogram Andrew 
Published: October 2013

AbstractWater Conservation Area 2A in the Florida Everglades is characterized by a nutrient gradient with high levels in the north from agricultural runoff and more oligotrophic conditions in the southern interior. Based on laboratory incubations and field studies, we found that the relative importance of methane (CH4) production mechanisms shifted along this gradient, with a greater contribution due to hydrogenotrophic methanogenesis at higher nutrient levels. The relative contributions of hydrogenotrophic and acetoclastic methanogenesis were determined from laboratory experiments and verified with field results. In the lab the relative contributions of the two pathways were determined from the differences in CH4 production rates in soil collected from sites along the nutrient gradient that was incubated with and without an inhibitor of acetoclastic methanogenesis (methyl fluoride, CH3F). In the nutrient‐poor soil, most of the CH4 was formed via acetate fermentation and only 25% came from hydrogenotrophic methanogenesis. At the nutrient‐impacted site CH4 was produced at fourfold higher rates and the proportion of CH4 produced via hydrogenotrophic methanogenesis increased to 50%. Isotopic fractionation factors for hydrogenotrophic and acetoclastic methanogenesis were calculated from the soil incubations and applied to δ13C‐CO2 and δ13C‐CH4 measured in pore water from the same transect. The trend of increased hydrogenotrophic relative to acetoclastic CH4 production along the nutrient‐impacted gradient was mirrored in the field data, which produced similar results to the lab incubation work, with up to 23% of the CH4 produced from hydrogenotrophic methanogenesis at the nutrient‐poor site and nearly half at the nutrient‐impacted site.
Cholecystectomy by using a surgical robotic system
Authors: Romero‐Talamás Héctor , Kroh Matthew 
Published: October 2013

AbstractBecause of their frequency, hepato‐biliary procedures have been the gateway for innovation to permeate into the realm of general surgery. Robotics and single‐incision techniques are the latest manifestation in the evolution of minimally invasive surgery. Enthusiasm for the latter has increased due to its inarguably superior cosmetic result. Nevertheless, there are several technical disadvantages associated with this approach that have raised several concerns. The robotic platform may provide a solution to these issues. We analyze the strengths and weaknesses of the robotic system for cholecystectomy and its relation to single site technology. We review all available literature addressing robotic single site cholecystectomy. Due to the advent of specific robotic single site technology, many of the challenges commonly associated with single site cholecystectomy have been alleviated. Although this novel approach has not yet been extensively tested, the available evidence suggests that it is at least equivalent to LC in selected patients. Robotic single site cholecystectomy is safe and feasible and adequately compensates for many of the challenges commonly associated with conventional single site cholecystectomy. Large, high‐quality studies are needed to further clarify the role of this procedure and its value as part of the surgeon's armamentarium.
New technologies for single‐site robotic surgery in hepato‐biliary‐pancreatic surgery
Authors: Diana Michele , Pessaux Patrick , Marescaux Jacques 
Published: October 2013

AbstractLaparoendoscopic single‐site surgery (LESS) aims to reduce incision‐related complications by using a single surgical access through which multiple instruments are inserted simultaneously. First descriptions of LESS procedures date back to the early 90s, but the approach initially failed to gain popularity because of technical challenges that markedly impair the principles of laparoscopic ergonomics. In recent years LESS has been increasingly applied to hepatobiliary procedures including cholecystectomies and liver resections. However, the uptake of LESS in hepatobiliary is limited. The surgical robotic platform might play a fundamental role in facilitating the uptake of LESS by the surgical community since robotic science made it possible to develop adequate technology to deal with some of the LESS issues such as restoring surgical triangulation. In this paper the current state‐of‐the‐art for robotic LESS applied to the hepatobiliary system and emerging technologies enabling safer LESS procedures have been reviewed and future perspectives commented on the light of our experience.
Female donor to male recipient gender discordance results in inferior graft survival: a prospective study of 1,042 liver transplants
Authors: Croome Kristopher P. , Segal Dan , Hernandez‐Alejandro Roberto , Adams Paul C. , Thomson Alan , Chandok Natasha 
Published: October 2013

AbstractBackgroundThe influence of donor‐recipient gender mismatch on outcomes after liver transplantation (LT) is controversial. The aim of this study was to evaluate the effect of donor and recipient gender discordance on graft survival.MethodsAll patients who underwent primary LT from 1994–2012 at a single‐center were identified prospectively. Clinico‐demographic data were collected at the time of LT and last follow‐up. Gender match included both male donor to male recipient (MM) and female donor to female recipient (FF), while gender mismatch included female donor to male recipient (FM) and male donor to female recipient (MF). Survival curves for graft survival were generated using Kaplan–Meier method and compared by log‐rank test. Unadjusted and multivariate adjusted COX regression analyzing graft survival at up to 10 years post‐transplant was performed.ResultsA total of 1,042 subjects fulfilled the criteria. Graft survival in patients receiving a donor‐recipient gender match was better than those receiving a gender mismatch (P = 0.047). Female‐to‐male transplants had the worst graft survival of all combinations (P < 0.001); this difference was maintained in multivariate regression after adjustment for recipient and donor variables (hazards ratio 2.09, P = 0.013).ConclusionFemale‐to‐male liver transplants are associated with a statistically significant poorer graft survival as compared with other donor‐recipient gender groups.
Technique of endoscopic ultrasonography‐guided pancreatic duct intervention (with videos)
Authors: Itoi Takao , Yasuda Ichiro , Kurihara Toshio , Itokawa Fumihide , Kasuya Kazuhiko 
Published: October 2013

Abstract To date, several endoscopic ultrasonography (EUS)‐guided interventions have been reported. Of these interventions, EUS‐guided pancreatic duct (PD) intervention seems to be the most difficult and challenging procedure to accomplish. We provide suggestions for EUS‐guided PD intervention, which includes PD stenting and the rendezvous technique following EUS‐guided pancreatography. PD stenting is performed between the PD and the gastrointestinal tract (stomach, duodenum, or jejunum). The rendezvous technique is performed using a guidewire across the papilla or anastomotic site for retrograde stent insertion. EUS‐guided PD intervention is still challenging because it is not established yet. Thus, although EUS‐guided PD intervention seems to be promising, it should be performed in selected patients such as those of failed standard endoscopic retrograde cholangiopancreatography.
CONTRIBUTION DENSITIES, TRANSITIONS AND PENSION RIGHTS: THE CASE OF JORDAN
Authors: Forteza Alvaro , Mussio Irene 
Published: October 2013

AbstractUsing micro‐data from the Social Security Corporation (SSC), we analyse the dynamics of social security coverage in the Jordanian labour force. We characterise patterns of contribution densities and transition rates and fit survival models for transitions. We also simulate pension rights. We compare patterns in the Jordanian SSC and in social security programmes in three Latin American countries for which a similar analysis has been conducted. We find comparatively low contribution densities and transition rates in Jordan, which is consistent with low coverage and low turnover rates. Copyright © 2013 John Wiley & Sons, Ltd.
Determinants of Household Vulnerability to Food Insecurity: A Case Study of Semi‐Arid Districts in Malawi
Authors: Kakota Tasokwa , Nyariki Dickson , Mkwambisi David , Kogi‐Makau Wambui 
Published: October 2013

AbstractThis paper looks at household vulnerability to food insecurity and its determinants in two semi‐arid districts in Malawi. A randomly selected sample of 200 households was interviewed. The descriptive statistics revealed that female‐headed households were more vulnerable to food insecurity than male‐headed households because of low access to resources for food production and purchases. A two‐stage least squares regression analysis showed that amongst the main determinants of household vulnerability were income, household size, land size and access to climate information. The findings imply that policies should promote diversification of livelihoods and equal opportunities and rights to access resources. Copyright © 2013 John Wiley & Sons, Ltd.
Morphofunctional transformations of the yolk syncytial layer during zebrafish development
Authors: Kondakova Ekaterina Alexandrovna A. , Efremov Vladimir Ivanovich I. 
Published: October 2013

ABSTRACTThe yolk syncytial layer (YSL) is a provisory extraembryonic structure of teleost fishes and representatives of some other taxa with meroblastic cleavage. The YSL of teleosts is a symplast with polymorphous polyploid nuclei. It is known to perform nutritional, morphogenetic, immune, and, probably, other functions. Data about the YSL organization, functioning and regulation is fragmentary. Although gene expression patterns and other aspects of YSL functioning have been studied in Danio rerio, the morphology of its YSL has not been described in detail. The study of zebrafish YSL structure on sequential developmental stages is necessary to recognize specific features of this important polyfunctional system in this model organism and to extend our knowledge about provisory systems. The thickness of the YSL and the distribution of its nuclei are not uniform on each stage and change during development. During oblong and sphere stages the internal YSL (I‐YSL) is filled with yolk inclusions; interphase yolk syncytial nuclei (YSN) and mitotic asters can be seen. During doming and epiboly the external YSL (E‐YSL) is thicker than I‐YSL. On the subsequent stages the YSL is thickened caudally. The dorsal YSL part is thickened during early segmentation stages and becomes the thinnest YSL region later. The anterior part of the YSL is thin, but enlarges during larval period. The YSN of different size and diverse forms, from regular to lobed, are present and form clusters. The number of irregular‐shaped nuclei increases during development. The YSL thickens in the end of endotrophic and in the course of endo‐exotrophic period, and its cytoplasm contains numerous yolk inclusions. After yolk exhaustion the YSL is flat. As the YSL degrades, the YSN become pycnotic, and the YSL remnant probably is cleared by phagocytes. J. Morphol. 275:206–216, 2014. © 2013 Wiley Periodicals, Inc.
Magnetic resonance elastography of liver in healthy asians: Normal liver stiffness quantification and reproducibility assessment
Authors: Venkatesh Sudhakar K. , Wang Gang , Teo Lynette L.S. , Ang Bertrand W.L. 
Published: October 2013

PurposeTo determine normal liver stiffness values evaluated with magnetic resonance elastography (MRE) in healthy normal Asian volunteers and assess its reproducibility.Materials and MethodsLiver stiffness was evaluated with MRE in 41 healthy Asians (23 females, 18 males; mean age, 41.8 years, and mean body mass index [BMI], 23.4 kg/m2) on a 1.5T clinical scanner. The correlations between mean liver stiffness and age, gender, BMI, and fat fraction percentage of the liver were studied. Another 12 volunteers underwent liver MRE exams on two separate days 4–6 weeks apart under similar conditions for reproducibility assessment. Intraclass correlation coefficient (ICC) analysis was performed and within‐subject coefficient of variation (CV) of stiffness was estimated.ResultsThe mean ± standard deviation (SD) of liver stiffness in normal healthy Asian subjects was 2.09 ± 0.22 kPa (95% confidence interval [CI], 2.04–2.15 kPa; range 1.68–2.48 kPa). The mean liver stiffness did not significantly correlate with age, gender, BMI, or fat content of the liver. The ICC for mean liver stiffness was 0.90 (95% CI, 0.78–0.96) and CV ranged from 2.2%–11.4%.ConclusionThe liver stiffness in normal Asians is not affected by age, gender, BMI, or fat content. Liver stiffness with MRE is highly reproducible. J. Magn. Reson. Imaging 2014;39:1–8. © 2013 Wiley Periodicals, Inc.