bluuebunny/crossref_metadata_2025 huggingface dataset:
4D-Trajectory Air Traffic Management: ‘Are There ‘Killer Apps?’ – Part 1
Authors: Brooker Peter
Published: March 2012

Europe and the USA are developing plans (‘SESAR’ and ‘NextGen’) to transform the processes of Air Traffic Management (ATM). These will improve safety and efficiency, and match predicted increases in air transportation demand. Aircraft would fly on Four Dimensional-Trajectories (4D-Trajectories), incorporating altitude, position, time, and other aircraft positions and vectors. This vision would involve extremely large investments from the airline industry and ATM service providers. Thus, development priorities need to be based on sound business cases. But will these necessarily lead to the strategic vision of a 4D-Trajectory system? Will the changes in practice be limited to a series of short and medium term operational improvements rather than strategic improvements? Killer App(lication)s is jargon for innovations so valuable that they prove the core value of some larger technology. So, are there ‘Killer Apps’ for 4D-Trajectory ATM? Killer Apps generate high degrees of stakeholder technical and financial cooperation. Ironically, most past ATM Killer Apps have improved safety. The analysis here attempts to identify and then size potential 4D-Trajectory ATM Killer Apps. The evidence for Killer Apps has to pass key tests. Killer Apps obviously have to offer enormous benefits to stakeholders in the context of the potential costs. The bulk of these benefits must not be obtainable through technologically ‘cut down’ non−4D-Trajectory versions. Part 1 of this paper sets out the framework for investigating these questions; Part 2 will be published subsequently and will examine potential Killer Apps derived from improvements in Fuel Efficiency, Capacity and Cost. An abbreviated version of this paper was first presented at the European Navigation Conference (ENC 2011), London in November 2011.
A stochastic analysis of greedy routing in a spatially dependent sensor network
Authors: KEELER HOLGER P.
Published: March 2012

For a sensor network, a tractable spatially dependent node deployment model is presented with the property that the density is inversely proportional to the sink distance. A stochastic model is formulated to examine message advancements under greedy routing in such a sensor network. The aim of this work is to demonstrate that an inhomogeneous Poisson process can be used to model a sensor network with spatially dependent node density. Symmetric elliptic integrals and asymptotic approximations are used to describe the random behaviour of hops. Types of dependence that affect hop advancements are examined. We observe that the dependence between successive jumps in a multi-hop path is captured by including only the previous forwarding node location. We include a simple uncoordinated sleep scheme, and observe that the complexity of the model is reduced when sufficiently many nodes are asleep. All expressions involving multi-dimensional integrals are derived and evaluated with quasi-Monte Carlo integration methods based on Halton sequences and recently developed lattice rules. An importance sampling function is derived to speed up the quasi-Monte Carlo methods. The ensuing results agree extremely well with simulations.
Aortic stenosis: current treatment options for a common condition in old age
Authors: Tiwari D , Radvan J , Allen SC
Published: March 2012

Degenerative-calcific aortic stenosis is mainly a disease of old age. Patients with mild to moderate stenosis without symptoms and those with aortic valve sclerosis do not require mechanical intervention. There is no firm evidence that the rate of progression can be modified by medical therapies, though statins might have some effect. Patients who develop severe stenosis with symptoms have a very poor prognosis if managed medically. Surgical aortic valve replacement greatly improves symptoms and mortality rates and remains the treatment of choice for those fit for major surgery, even above the age of 80 years. For those not suitable for surgery, or who are unwilling to have an operation, outcomes can be significantly improved by trans-catheter aortic valve replacement, which has become an important option for frail elderly patients. Balloon aortic valvuloplasty improves symptoms and short-term survival, but has a less clear impact on mortality beyond 1 year. It is useful as a palliative treatment and as a bridging procedure for patients who are not ready for valve replacement. There is less agreement on the best approach to patients with asymptomatic severe aortic stenosis. Trials indicate that early valve replacement results in outcomes that are comparable to those seen in symptomatic patients, though guidelines advocate delaying surgery until symptoms occur or left ventricular function begins to decline rapidly. All elderly patients with severe aortic stenosis should be considered for a mechanical intervention unless there is a properly considered reason for not doing so, or they are not willing to receive such treatment.
Subarachnoid Hemorrhage in Wegener Granulomatosis: A Case Report and Review of the Literature
Authors: Miles J. Douglas , McWilliams Laurie , Liu Wendy , Preston David C.
Published: March 2012

Wegener granulomatosis (WG) is an uncommon, idiopathic disorder that is characterized by granulomatous inflammation of the upper and lower respiratory tract, disseminated vasculitis involving small and medium-sized vessels, and focal segmental glomerulonephritis. Approximately 25% to 50% of patients have nervous system involvement. The brain is less frequently involved. We report a case of a 74 year-old previously well woman who presented with rapidly progressing WG that culminated in subarachnoid hemorrhage. Only six cases of subarachnoid hemorrhage in the setting of WG have previously been reported. We review the common presenting signs and symptoms, diagnosis, treatment, and complications of WG.
Ethnicity and Age at Onset in Bipolar Spectrum Disorders
Authors: Javaid Naima , Kennedy James L. , De Luca Vincenzo
Published: March 2012

Introduction

To determine the influence of ethnicity on the age at onset (AAO) and further understand the significance of AAO as a clinical marker of bipolar and schizoaffective disorders.

Methods

Admixture analysis was used to identify sub-groups characterized by differences in AAO. Differences in clinical features were analyzed for these sub-groups using multivariate logistic regression. Comparisons were made with previous studies using the 2-Sample Kolmogorov-Smirnov Test.

Results

Admixture analysis yielded a combination of 2 normal theoretical distributions with means (SD) of 16.9 (3.6) for the early-onset sub-group and 24.4 (9.2) years for the late-onset sub-group. The sub-groups were divided by a cut-off of 22 years. There were significant differences between the early and late onset bipolar patient populations regarding substance abuse comorbidity (P=.044) and psychotic features (P=.015). Ethnicity did not have a significant influence on the AAO.

Discussion

The associations between early-onset and higher incidence of psychosis and substance abuse in our sample are consistent with other studies exploring the AAO in bipolar disorder.

Conclusion

Our findings support the notion of AAO as a clinical marker for the underlying heterogeneity of bipolar spectrum disorders. In particular, we found a strong overlap of early AAO with clinical features associated with greater severity and poor outcome.
Symptom Dimensional Approach and BDNF in Unmedicated Obsessive-Compulsive Patients: An Exploratory Study
Authors: dos Santos Igor Marcanti , Ciulla Leandro , Braga Daniela , Ceresér Keila Maria , Gama Clarissa Severino , Kapczinski Flávio , Ferrão Ygor Arzeno
Published: March 2012

Introduction

The dimensional approach of the obsessive-compulsive symptoms may help to find more homogeneous groups of patients. The brain derived neurotrophic factor (BDNF) may help to identify neurobiological differences between obsessive-compulsive symptom dimensions.

Methods

We compared serum BDNF (pg/μg) levels of 25 unmedicated patients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for obsessivecompulsive disorder (OCD) and 25 controls, using the Dimensional Yale‐Brown Obsessive‐Compulsive Scale, the Yale‐Brown Obsessive‐Compulsive Scale and the Beck's Anxiety and Depression Inventories.

Results

There were no sociodemographic differences between the groups. The standard error of mean serum BDNF levels were reduced in unmedicated OCD patients (0.47+0.038) when compared to healthy controls (0.75+0.060) (P<.001). The patients with the presence of sex/religion obsessive-compulsive symptoms (OCS) dimension (P=.002), with chronic course of OCS (P=.022) and the presence of lifetime major depression (P=.016) and social anxiety (P=.030) presented higher levels of BDNF than OCD patients without those features. The severity of aggression (P=.039) and sex/religion (P<.001) OCS dimension presented direct (moderate and strong, respectively) correlation with serum BDNF levels in this sample. Serum BDNF levels were decreased in OCD patients when compared to healthy controls.

Discussion/Conclusion

Sexual and religious content of symptoms and aggression and sex/religion dimensions severity should be better explored, since these specific OCS dimensions could be based on neurocircuits diverse from those of the other OCS dimensions.
The Role of Emotion in PTSD: Two Preliminary Studies
Authors: Power Mick J. , Fyvie Claire
Published: March 2012

Background: Two studies are presented that highlight the role of emotion in PTSD in which we examine what emotions in addition to anxiety may be present. Aims: The first aim was to assess the overall emotion profile across the five basic emotions of anxiety, sadness, anger, disgust, and happiness in clients attending a stress clinic. A small pilot study was also carried out to see how the emotion profiles impacted on outcome for CBT. Method: In Study 1, 75 consecutive attenders at a trauma service who were diagnosed with PTSD were assessed with a number of measures that included the Basic Emotions Scale. Results: The results showed that less than 50% of PTSD cases presented with anxiety as the primary emotion, with the remainder showing primary emotions of sadness, anger, or disgust rather than anxiety. A second pilot study involved the follow-up across exposure-based CBT of 20 of the participants from Study 1. Conclusions: The results suggest that anxiety-based PTSD is more likely to benefit from exposure than is non-anxiety based PTSD. Implications both for the classification and the treatment of PTSD are considered.
Detention by armed groups: overcoming challenges to humanitarian action
Authors: Tuck David
Published: March 2012

Armed conflict and deprivation of liberty are inexorably linked. Deprivation of liberty by non-state armed groups is a consequence of the predominantly non-international character of contemporary armed conflicts. Regardless of the nature of the detaining authority or the overarching legality of its detention operations, deprivation of liberty may nonetheless have serious humanitarian implications for the individuals detained. Despite a need for humanitarian action, effective engagement is hampered by certain threshold obstacles, such as the perceived risk of the group's legitimization. Since the formative work of the International Committee of the Red Cross (ICRC)'s founder, Henry Dunant, the ICRC has sought to overcome these obstacles. In doing so it draws upon its experience of humanitarian action in state detention, adapting it to the exigencies of armed groups and the peculiarities of their detention practice. Although not without setbacks, the ICRC retains a unique role in this regard and strives to ameliorate the treatment and conditions of detention of persons deprived of liberty by armed groups.
Entwicklung und Validierung eines Fragebogens zur Erfassung von „Adaptive Performance“
Authors: Kröger Ulrike , Staufenbiel Thomas
Published: March 2012

Gegenstand ist die Entwicklung und Validierung eines Fragebogens zur Erfassung von Adaptive Performance (AP). AP wird definiert als ein Verhalten, mit dem auf eine veränderte Arbeitssituation reagiert wird und das funktional für die Erreichung der Unternehmensziele ist. Hypothesenkonform zeigt sich sowohl bei Vorgesetztenbeurteilungen als auch bei Selbsteinschätzungen eine zweidimensionale Struktur des neu entwickelten Instruments, bei der zwischen einer aufgabenbezogenen und einer sozialen Form von Adaptivität unterschieden wird. In zwei Studien wird gezeigt, dass sich AP empirisch von der Aufgabenleistung (in-role performance) abgrenzen lässt und dass AP eine spezifische Rolle bei der globalen Bewertung der Leistung von Mitarbeitern durch Vorgesetzte spielt. Im Rahmen weiterer Validierungen zeigen sich ferner positive Zusammenhänge mit den Traits Flexibilität und Kontaktfähigkeit, wobei erwartungsgemäß Flexibilität höher mit der aufgabenbezogenen und Kontaktfähigkeit höher mit der sozialen AP korreliert.
Lifetime Risk of Suicidal Behaviors and Communication to a Health Professional About Suicidal Ideation
Authors: Encrenaz Gaëlle , Kovess-Masféty Viviane , Gilbert Fabien , Galéra Cédric , Lagarde Emmanuel , Mishara Brian , Messiah Antoine
Published: March 2012

Background: There is presently a lack of information on the role of healthcare in suicidal ideation in adults. Aims: To assess the frequencies, patterns, and factors associated with the communication of suicidal ideation toward a health professional. Methods: Participants stem from a French cross-sectional survey of 22,133 randomly selected adults. Lifetime suicidal behaviors and 12-month mental disorder patterns were assessed using the short form of the Composite International Diagnostic Interview. Participants with suicidal ideation were asked whether they had talked about it and, if they had, to whom. Results: Around 20% of people with suicidal ideation had talked about this distress to a health professional. It was more frequent for people with more severe suicidal behaviors (plan or a prior attempt), among women, those aged 30 or more, those suffering from major depressive episode, panic disorder, or drug use disorder. Above all, it was more frequent among those who had also talked to friends or relatives. Conclusions: Prevention strategies that encourage suicidal persons to seek help for their distress, whoever that is, may be the more important strategies to develop.
Internet Comments Elicited by Media Portrayal of a Familicide-Suicide Case
Authors: Sisask Merike , Mark Lauraliisa , Värnik Airi
Published: March 2012

Background: Events of extraordinary violence attract media attention. Recently, much media reporting has moved to the Internet, giving readers the possibility to comment online. Aims: To analyze the content of public cognitions and the emotional tonality of attitudes expressed in spontaneous Internet comments on a familicide-suicide case reported in the Estonian media. Methods: A content analysis is based on the comments of 6,333 readers following media coverage. Descriptive statistics were used for quantitative data analysis. Results: Of all comments, 27.6% were without manifest content. Manifest content categories were “value judgments” (35.2%), “risk and protective factors” (27.2%), and “critics of media portrayal” (10.0%). As to emotional tonality, the comments were most often angry (34.5%), ironic (24.7%), or neutral (23.3%). “Critics of media portrayal” had the most clearly pronounced emotional tonality, the majority being angry or approving. Comments about “value judgments” were most frequently anguished. Conclusions: An analysis of Internet comments can provide valuable information about value judgments and attitudes in society. From an ethical and preventive perspective, similar homicide and suicide stories should not be open for unmoderated public discussion. Nevertheless, the study represents an original methodological approach for such research and also provides some guidance for public relations campaigns.
Evaluating triple oxygen isotope estimates of gross primary production at the Hawaii Ocean Time‐series and Bermuda Atlantic Time‐series Study sites
Authors: Nicholson David P. , Stanley Rachel H. R. , Barkan Eugeni , Karl David M. , Luz Boaz , Quay Paul D. , Doney Scott C.
Published: March 2012

The triple oxygen isotopic composition of dissolved oxygen (17Δ) is a promising tracer of gross oxygen productivity (P) in the ocean. Recent studies have inferred a high and variable ratio of P to 14C net primary productivity (12–24 h incubations) (e.g., P:NPP(14C) of 5–10) using the 17Δ tracer method, which implies a very low efficiency of phytoplankton growth rates relative to gross photosynthetic rates. We added oxygen isotopes to a one‐dimensional mixed layer model to assess the role of physical dynamics in potentially biasing estimates ofP using the 17Δ tracer method at the Bermuda Atlantic Time‐series Study (BATS) and Hawaii Ocean Time‐series (HOT). Model results were compared to multiyear observations at each site. Entrainment of high17Δ thermocline water into the mixed layer was the largest source of error in estimating P from mixed layer 17Δ. At both BATS and HOT, entrainment bias was significant throughout the year and resulted in an annually averaged overestimate of mixed layer P of 60 to 80%. When the entrainment bias is corrected for, P calculated from observed 17Δ and 14C productivity incubations results in a gross:net productivity ratio of 2.6 (+0.9 −0.8) at BATS. At HOT a gross:net ratio decreasing linearly from 3.0 (+1.0 −0.8) at the surface to 1.4 (+0.6 −0.6) at depth best reproduced observations. In the seasonal thermocline at BATS, however, a significantly higher gross:net ratio or large lateral fluxes of 17Δ must be invoked to explain 17Δ field observations.
Conceptual design and quantification of phosphorus flows and balances at the country scale: The case of France
Authors: Senthilkumar Kalimuthu , Nesme Thomas , Mollier Alain , Pellerin Sylvain
Published: March 2012

Global biogeochemical cycles have been deeply modified by human activities in recent decades. But detailed studies analyzing the influence of current economic and social organizations on global biogeochemical cycles within a system perspective are still required. Country level offers a relevant scale for assessing nutrient management and identifying key driving forces and possible leaks in the nutrient cycle. Conceptual modeling helps to quantify nutrient flows within the country and we developed such an approach for France. France is a typical Western European country with intensive agriculture, trade and an affluent diet, all of which may increase internal and external P flows. Phosphorus (P) was taken as a case study because phosphate rock is a non‐renewable resource which future availability is becoming increasingly bleak. A conceptual model of major P flows at the country scale was designed. France was divided into agriculture, industry, domestic, import and export sectors, and each of these sectors was further divided into compartments. A total of 25 internal and eight external P flows were identified and quantified on a yearly basis for a period of 16 years (from 1990 to 2006) in order to understand long‐term P flows. All the P flows were quantified using the substance flow analysis principle. The results showed that the industrial sector remained the largest contributor to P flows in France, followed by the agriculture and domestic sectors. Soil P balance was positive. However, a positive P balance of 18 kg P ha−1 in 1990 was reduced to 4 kg P ha−1 in 2006, mainly due to the reduced application of inorganic P fertilizer. The overall country scale P balance was positive, whereas half of this additional P was lost to the environment mainly through the landfilling of municipal and industrial waste, disposal of treated wastewater from which P was partially removed, and P losses from agricultural soils though erosion and leaching. Consequences for global P resources and soil and water compartments are discussed. Some opportunities to more effectively close the P cycle in France by both improving the intensity of P recycling and decreasing losses are quantified.
Quiet time variability of the GPS TEC and EEJ strength over Indian region associated with major sudden stratospheric warming events during 2005/2006
Authors: Sripathi S. , Bhattacharyya A.
Published: March 2012

This paper describes the quiet time variabilities of the ionospheric total electron content (TEC) derived from the signals from Global Positioning Satellite System (GPS) recorded at several stations in India along with simultaneous observations of equatorial electrojet (EEJ) strength obtained from geomagnetic field variations during January–March 2006 when sudden stratospheric warming (SSW) events occurred. Analysis of the observations presented here confirms that strong correlation exists among the variabilities in EEJ strength and GPS TEC observations. Investigations suggest that there exist large‐scale wave like structures with periodicity of quasi 16‐day wave in the TEC observations near the equatorial ionization anomaly (EIA) crest quite similar to that of EEJ strength. Our observations also indicate the existence of morning enhancement and evening reduction of TEC and EEJ strength and vice versa during SSW events similar to that reported elsewhere. Using these observations, it is suggested that the quiet time variabilities seen in the GPS TEC over EIA could be caused due to the nonlinear interaction of upward propagating planetary waves (PWs) with atmospheric tides. Presence of similar periods in the EEJ strength and TEC observations near the EIA crest region, supports the view that the large‐scale wave like structures seen in TEC near the EIA crest are associated with PWs that are modifying the primary eastward electric field in the equatorial E region and hence the EEJ strength through non linear interactions with atmospheric tides.
Identification of electron field‐aligned current systems in Saturn's magnetosphere
Authors: Schippers P. , André N. , Gurnett D. A. , Lewis G. R. , Persoon A. M. , Coates A. J.
Published: March 2012

Based on the analysis of 7 years of Cassini electron plasma spectrometer data near Saturn's equatorial plane, we computed the average directional electron current in the Northern and the Southern hemispheres separately. We determined the net current density by subtracting the downward electron current density (equator to the ionosphere) from the upward electron current density (ionosphere to the equator). From the symmetric analysis (no separation in local time), we identified: (1) layers of net upward current carried by the thermal electrons (1–10 eV) in both hemispheres inside 5–8 RS (Saturn Radius = 60,268 km) (region A) and (2) layers of net downward current carried by a population of warmer electrons (10–400 eV) inside 8–10 RS (region B). From the analysis of the currents organized by local time (dayside and nightside parsing), new features were identified such as (1) a day‐night asymmetry of the current carried by the warm and hot (400 eV–26,000 eV) electrons beyond 10 RS (region C), and (2) the possible existence of inter‐hemispheric currents directed from the Southern to the Northern hemisphere inside 4 RS (region A) and oppositely directed at about 13–15 RS (region C). Our interpretation is that the observed current system results from the superimposition of (1) a current system associated with the corotation enforcement, (2) a current system linked to the presence of the newly identified noon‐to‐midnight convection electric field and (3) a system of inter‐hemispheric currents driven by the thermosphere‐ionosphere. We finally discuss the relation of the observed currents with the newly identified Saturn's secondary auroral emissions.
Structure and anisotropy of the Mexico subduction zone based on Rayleigh‐wave analysis and implications for the geometry of the Trans‐Mexican Volcanic Belt
Authors: Stubailo I. , Beghein C. , Davis P. M.
Published: March 2012

We develop a three‐dimensional model of shear wave velocity and anisotropy for the Mexico subduction zone using Rayleigh wave phase velocity dispersion measurements. This region is characterized by both steep and flat subduction and a volcanic arc that appears to be oblique to the trench. We give a new interpretation of the volcanic arc obliqueness and the location of the Tzitzio gap in volcanism based on the subduction morphology. We employ the two‐station method to measure Rayleigh phase velocity dispersion curves between periods of 16 s to 171 s. The results are then inverted to obtain azimuthally anisotropic phase velocity maps and to model 3‐D variations in upper mantle velocity and anisotropy. Our maps reveal lateral variations in phase velocity at all periods, consistent with the presence of flat and steep subduction. We also find that the data are consistent with two layers of anisotropy beneath Mexico: a crustal layer, with the fast directions parallel to the North American absolute plate motion, and a deeper layer that includes the mantle lithosphere and the asthenosphere, with the fast direction interpreted in terms of toroidal mantle flow around the slab edges. Our combined azimuthal anisotropy and velocity model enables us to analyze the transition from flat to steep subduction and to determine whether the transition involves a tear resulting in a gap between segments or is a continuous deformation caused by a lithospheric flexure. Our anisotropy results favor a tear, which is also consistent with the geometry of the volcanic belt.
Hydrogeochemical numerical simulation of impacts of mineralogical compositions and convective fluid flow on trapping mechanisms and efficiency of carbon dioxide injected into deep saline sandstone aquifers
Authors: Kihm Jung‐Hwi , Kim Jun‐Mo , Wang Sookyun , Xu Tianfu
Published: March 2012

A series of numerical simulations, which consider density‐dependent (convective) groundwater and carbon dioxide (CO2) flow, is performed using a multiphase hydrogeochemical reactive transport numerical model to evaluate impacts of mineralogical compositions on the trapping mechanisms and efficiency of CO2 injected into a deep saline sandstone aquifer (reservoir rock). The results of the numerical simulations show that the mineralogical compositions of the sandstone aquifer have significant impacts on hydrogeochemical behavior of injected CO2 and thus its trapping mechanisms and efficiency. Injected CO2 is accumulated as a free fluid phase beneath the caprock (i.e., hydrodynamic trapping), then dissolved as aqueous phases such as bicarbonate and carbonate anions into groundwater (i.e., solubility trapping), and finally precipitated as carbonate minerals (i.e., mineral trapping). Mineral trapping of injected CO2 takes places as precipitation of a primary carbonate mineral such as calcite and secondary carbonate minerals such as dawsonite, siderite, ankerite, and magnesite. The patterns of hydrogeochemical reactions depend significantly on the initial presence and absence of chlorite in the sandstone aquifer. For mineral trapping of injected CO2, ankerite is the most dominant mineral when chlorite is initially present, whereas dawsonite is the most dominant mineral when chlorite is initially absent in the sandstone aquifer. Mg2+ and Fe2+, which are essential chemical components of such secondary carbonate minerals (i.e., siderite, ankerite, and magnesite) for mineral trapping of injected CO2, are mainly supplied by dissolution of chlorite. As a result, the precipitation amounts of the secondary carbonate minerals and thus the efficiency of mineral trapping of injected CO2 increase significantly as the volume fraction of chlorite increases in the sandstone aquifer. A series of additional numerical simulations, which consider density‐independent (non‐convective) multiphase fluid flow, is also performed using the same numerical model, and then its results are compared with those of the above‐mentioned numerical simulations, which consider density‐dependent (convective) multiphase fluid flow, to evaluate impacts of convective fluid flow on the trapping mechanisms and efficiency of injected CO2. The comparison of the results of both numerical simulations shows that convective fluid flow also has significant impacts on hydrogeochemical behavior of injected CO2 and thus its trapping mechanisms and efficiency. Convective fluid flow reduces the free fluid phase of CO2 (i.e., hydrodynamic trapping) and thus enhances the aqueous and solid phases of CO2 (i.e., initially solubility trapping and then mineral trapping).
Factors controlling the mode of rift interaction in brittle‐ductile coupled systems: A 3D numerical study
Authors: Allken Vaneeda , Huismans Ritske S. , Thieulot Cedric
Published: March 2012

The way individual faults and rift segments link up is a fundamental aspect of lithosphere extension and continental break‐up. Little is known however about the factors that control the selection of the different modes of rift interaction observed in nature. Here we use state‐of‐the‐art large deformation 3D numerical models to examine the controls on the style and geometry of rift linkage between rift segments during extension of crustal brittle‐ductile coupled systems. We focus on the effect of viscosity of the lower layer, the offset between the rift basins and the amount of strain weakening on the efficiency of rift linkage and rift propagation and the style of extension. The models predict three main modes of rift interaction: 1) oblique to transform linking graben systems for small to moderate rift offset and low lower layer viscosity, 2) propagating but non linking and overlapping primary grabens for larger offset and intermediate lower layer viscosity, and 3) formation of multiple graben systems with inefficient rift propagation for high lower layer viscosity. The transition between the linking (Mode 1) and non‐linking mode (Mode 2) is controlled by the trade‐off between the rift offset, the strength of brittle‐ductile coupling, and the amount of strain weakening. The mode transition from overlapping non‐connecting rift segments (Mode 2) to distributed deformation (Mode 3) is mainly controlled by the viscosity of the lower layer and can be understood from minimum energy dissipation analysis arguments.
Chlorate salts and solutions on Mars
Authors: Hanley Jennifer , Chevrier Vincent F. , Berget Deanna J. , Adams Robert D.
Published: March 2012

Chlorate (ClO3−) is an intermediate oxidation species between chloride (Cl−) and perchlorate (ClO4−), both of which were found at the landing site by the Wet Chemistry Lab (WCL). The chlorate ion is almost as stable as perchlorate, and appears to be associated with perchlorate in most terrestrial reservoirs (e.g. Atacama and Antarctica). It is possible that chlorate contributed to the ion sensor response on the WCL, yet was masked by the strong perchlorate signal. However, very little is known about chlorate salts and their effect on the stability of water. We performed evaporation rate experiments in our Mars simulation chamber, which enabled us to determine the activity of water for various concentrations. From this we constructed solubility diagrams for NaClO3, KClO3, Mg(ClO3)2 and Ca(ClO3)2, and determined the Pitzer parameters for each salt. Chlorate salt eutectic temperatures range from 270 K (KClO3) to 204 K (Mg(ClO3)2). Modeling the addition of chlorate to the initial WCL solutions shows that it precipitates in concentrations comparable to other common salts, such as gypsum and epsomite, and implies that chlorates may play an important role in the wet chemistry on Mars.
Latitudinal anisotropy in ring current energetic neutral atoms
Authors: Goldstein J. , Valek P. , McComas D. J. , Redfern J.
Published: March 2012

Stereo energetic neutral atom (ENA) images obtained by Two Wide‐angle Imaging Neutral‐atom Spectrometers (TWINS) are analyzed to quantify the latitudinal anisotropy of ring current ENAs, and by implication, the system‐level pitch‐angle response during a moderate geomagnetic storm on 6 April 2010. During a 15‐min interval just after midday, TWINS 1 and 2 were at similar local times but different latitudes, and thus were able to simultaneously sample two different pitch angles from selected locations. The observations show a global dawn‐dusk asymmetry in the ring current ENA latitudinal anisotropy, the dusk side being ∼1–2 orders of magnitude more anisotropic than the dawn side. The latitudinal dependence of the ENAs implies a duskside ion distribution that is more equatorial than isotropic; this anisotropy becomes less pronounced with increasing energy. The observed dawn‐dusk ENA anisotropy may be caused by ring current ions drifting adiabatically in self‐consistently varying electric and (nondipolar) magnetic fields.
Magnetotail dipolarization front and associated ion reflection: Particle‐in‐cell simulations
Authors: Wu P. , Shay M. A.
Published: March 2012

For the Earth magnetotail, the Svenes et al. (2008) statistical study infers the lobe density to be highly variable, in the range of 0.007–0.092 cm−3. Such lobe density variation modifies reconnection diffusion region physical processes and reconnection rate drastically. This letter addresses observable reconnection signatures in the vicinity of the X‐line that are to be affected by the dynamic changes of reconnection. Using a 2.5D particle‐in‐cell (PIC) code, we find the dipolarization front (DF) a moving ram that pushes the initial equilibrium plasma sheet in front of it. The DF propagation velocity scales with the upstream Alfvén speed, leading to faster, steeper, and more compressed DFs with strongerBz at low lobe densities. These DFs reflect plasma sheet ions in a streaming manner. The streaming ions create a bipolar magnetic field straddling the central plasma sheet and can excite various instabilities.
Detailed properties of magnetospheric line radiation events observed by the DEMETER spacecraft
Authors: Němec F. , Parrot M. , Santolík O.
Published: March 2012

Magnetospheric line radiation (MLR) events are electromagnetic waves in the frequency range of about 1–8 kHz observed in the inner magnetosphere that, when presented in a form of frequency‐time spectrograms, consist of several nearly parallel and almost equidistant intense lines. Although many observations of these events have been reported using ground‐based instruments and a survey of a large data set based on low‐altitude satellite data has been published recently, their origin remains unclear. We use low‐altitude satellite observations of MLR events to study their detailed properties, namely, the frequency spacing of individual lines and their frequency drift. Since the satellite, unlike ground observatories, is moving, it allows us to analyze the properties of the events as a function of the position, especially L‐shell. We show that neither the frequency spacing of the events nor their frequency drift varies significantly with the L‐shell where the event is observed. Moreover, the frequency drift is generally positive. The individual lines forming the events cannot be explained as harmonics of the base frequency equal to the frequency spacing. We suggest that a possible generation mechanism might be an interaction between a wave of a carrier frequency and an additional wave with the frequency equal to the observed frequency spacing. We cannot exclude that it comes from human activity (power lines), but a magnetospheric origin is more likely. We suggest that the emissions might be guided by the plasmasphere inner boundary before they deviate to lower L‐shells at altitudes of a few thousands of kilometers.
SBML Reaction Finder: Retrieve and extract specific reactions from the BioModels database
Authors: Neal Maxwell , Sauro Herbert
Published: March 2012

Summary: The SBML Reaction Finder (SRF) application leverages the deep semantic annotations in the BioModels database to provide efficient retrieval and extraction of individual reactions from SBML models. We hope that the SRF will be useful to quantitative modelers who seek to accelerate their modeling efforts by reusing previously published representations of specific chemical reactions.Availability and Implementation: The SRF is open source, coded in Java, and distributed under the Mozilla Pubic License Version 1.1. Windows, Macintosh and Linux distributions are available for download at http://sourceforge.net/projects/sbmlrxnfinder.
Data Mining of the Coffee Rust Genome
Authors: Botero-Rozo David Octavio , Giraldo William , Gaitan Alvaro , Cristancho Marco , Riaño-Pachon Diego , Restrepo Silvia
Published: March 2012

The genomes of nine isolates of Hemileia vastatrix, the causal agent of coffee leaf rust were sequenced by Illumina and 454. Quality control, cleaning and de novo assemblies of data were performed. Since isolates were obtained from the field and it is not possible to produce axenic cultures of H. vastatrix, MEGAN software was used to evaluate contamination levels and to select contigs with fungal similarities. Mitochondrial contigs were identified and annotated by comparing this assembly against the Puccinia genome. Furthermore, two transcriptomes from isolates of H. vastatrix were assembled to complement the genomic data.
Chitin nanofibers: preparations, modifications, and applications
Authors: Ifuku Shinsuke , Saimoto Hiroyuki
Published: March 2012

Chitin nanofibers are prepared from the exoskeleton of crabs and prawns, which have novel applications.
EHD2 shuttles to the nucleus and represses transcription
Authors: Pekar Olga , Benjamin Sigi , Weidberg Hilla , Smaldone Silvia , Ramirez Francesco , Horowitz Mia
Published: March 2012

EHD {EH [Eps15 (epidermal growth factor receptor substrate 15) homology]-domain-containing} proteins participate in several endocytic events, such as the internalization and the recycling processes. There are four EHD proteins in mammalian cells, EHD1–EHD4, each with diverse roles in the recycling pathway of endocytosis. EHD2 is a plasma-membrane-associated member of the EHD family that regulates internalization. Since several endocytic proteins have been shown to undergo nucleocytoplasmic shuttling and have been assigned roles in regulation of gene expression, we tested the possibility that EHD proteins also shuttle to the nucleus. Our results showed that, among the three EHD proteins (EHD1–EHD3) that were tested, only EHD2 accumulates in the nucleus under nuclear export inhibition treatment. Moreover, the presence of a NLS (nuclear localization signal) was essential for its entry into the nucleus. Nuclear exit of EHD2 depended partially on its NES (nuclear export signal). Elimination of a potential SUMOylation site in EHD2 resulted in a major accumulation of the protein in the nucleus, indicating the involvement of SUMOylation in the nuclear exit of EHD2. We confirmed the SUMOylation of EHD2 by employing co-immunoprecipitation and the yeast two-hybrid system. Using GAL4-based transactivation assay as well as a KLF7 (Krüppel-like factor 7)-dependent transcription assay of the p21WAF1/Cip1 [CDKN1A (cyclin-dependent kinase inhibitor 1A)] gene, we showed that EHD2 represses transcription. qRT-PCR (quantitative real-time PCR) of RNA from cells overexpressing EHD2 or of RNA from cells knocked down for EHD2 confirmed that EHD2 represses transcription of the p21WAF1/Cip1 gene.
A functional description of CymA, an electron-transfer hub supporting anaerobic respiratory flexibility in Shewanella
Authors: Marritt Sophie J. , Lowe Thomas G. , Bye Jordan , McMillan Duncan G. G. , Shi Liang , Fredrickson Jim , Zachara John , Richardson David J. , Cheesman Myles R. , Jeuken Lars J. C. , Butt Julea N.
Published: March 2012

CymA (tetrahaem cytochrome c) is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis strain MR-1 identifies three low-spin His/His co-ordinated c-haems and a single high-spin c-haem with His/H2O co-ordination lying adjacent to the quinol-binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (approximately −240 mV) and low-spin (approximately −110, −190 and −265 mV) haems that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (Em=−80 mV) in the presence of NADH (Em=−320 mV) and an NADH–menadione (2-methyl-1,4-naphthoquinone) oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H2 oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a non-haem co-factor for quinol oxidation and that the reduced enzyme forms a 1:1 complex with its redox partner Fcc3 (flavocytochrome c3 fumarate reductase). The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.
Mousing around with caspases and IAPs
Authors: Rickert Robert C. , Salvesen Guy S. , Ware Carl F.
Published: March 2012

In a paper in this issue of the Biochemical Journal that questions the role of c-IAP1 (cellular inhibitor of apoptosis 1) in inflammation, new results from the Duckett laboratory remind us of the importance of truly knowing the mice we depend on. It turns out that c-IAP1 is tightly linked to caspase 11 and cannot be segregated by recombination. This disturbing result implies that immune functions ascribed to c-IAP1 may be due to the caspase 11 mutation that is co-inherited with the locus.
Atomistic simulations of liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2PhP and PhP14
Authors: Yan Fangyong , Earl David J.
Published: March 2012

We study liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2-[4-(butyloxy)phenyl]-5-(octyloxy)pyrimidine (2PhP) and 2-[4-(tetradecyloxy)phenyl]-5-(tetradecyloxy)pyrimidine (PhP14) using molecular dynamics simulations at the all atom level. The molecular length of PhP14 is 1.8 times that of 2PhP, resulting in an interesting binary mixture phase diagram. Our simulations are composed of 1000−1600 molecules for a total of 80 000−130 000 atomic sites, with total simulation times of 60−100 ns. We first show that a pure 2PhP system self-assembles into isotropic, nematic, smectic A and smectic C phases, and a pure PhP14 system self-assembles into isotropic and smectic C phases. Binary mixtures of PhP14 and 2PhP display a stabilization of the smectic A phase at the expense of the smectic C and nematic phases. We determine that the concentration-induced phase transition from the smectic C to the smectic A phase in the mixture is driven by an out-of-layer fluctuation arrangement of the molecules. We also observe that the tilt angle in the smectic C phases formed in the mixtures is concentration dependent. The results of our simulations are in good agreement with the experimental findings of Kapernaum et al. [J. Org. Chem. 5, 65 (2009)]10.3762/bjoc.5.65, thus showing that atomistic simulations are capable of reproducing the phase behavior of liquid crystal mixtures and can also provide microscopic details regarding the mechanisms that govern phase stability.
First-order finite-Larmor-radius fluid modeling of tearing and relaxation in a plasma pinch
Authors: King J. R. , Sovinec C. R. , Mirnov V. V.
Published: March 2012

Drift and Hall effects on magnetic tearing, island evolution, and relaxation in pinch configurations are investigated using a non-reduced first-order finite-Larmor-radius (FLR) fluid model with the nonideal magnetohydrodynamics (MHD) with rotation, open discussion (NIMROD) code [C.R. Sovinec and J. R. King, J. Comput. Phys. 229, 5803 (2010)]. An unexpected result with a uniform pressure profile is a drift effect that reduces the growth rate when the ion sound gyroradius (ρs) is smaller than the tearing-layer width. This drift is present only with warm-ion FLR modeling, and analytics show that it arises from ∇B and poloidal curvature represented in the Braginskii gyroviscous stress. Nonlinear single-helicity computations with experimentally relevant ρs values show that the warm-ion gyroviscous effects reduce saturated-island widths. Computations with multiple nonlinearly interacting tearing fluctuations find that m = 1 core-resonant-fluctuation amplitudes are reduced by a factor of two relative to single-fluid modeling by the warm-ion effects. These reduced core-resonant-fluctuation amplitudes compare favorably to edge coil measurements in the Madison Symmetric Torus (MST) reversed-field pinch [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)]. The computations demonstrate that fluctuations induce both MHD- and Hall-dynamo emfs during relaxation events. The presence of a Hall-dynamo emf implies a fluctuation-induced Maxwell stress, and the simulation results show net transport of parallel momentum. The computed magnitude of force densities from the Maxwell and competing Reynolds stresses, and changes in the parallel flow profile, are qualitatively and semi-quantitatively similar to measurements during relaxation in MST.
Magnetoresistance enhanced by inelastic cotunneling in a ferromagnetic MnAs nanoparticle sandwiched by nonmagnetic electrodes
Authors: Akiyama Ryota , Ohya Shinobu , Hai Pham Nam , Tanaka Masaaki
Published: March 2012

We investigated electron transport and magnetoresistance (MR) of a nanoparticle system by measuring the vertical transport in heterostructures containing ferromagnetic MnAs nanoparticles and nonmagnetic electrodes. The origin of MR is attributed to the tunneling anisotropic MR (TAMR) of a MnAs nanoparticle because the path of electrons includes only a single ferromagnetic material, and MR shows magnetic-field direction dependence. From the very similar temperature dependence of the intensity of inelastic cotunneling and MR, it is strongly suggested that MR is enhanced by spin-dependent inelastic cotunneling. The temperature dependence of MR is explained by the magnetic energy barrier ETAMR induced by TAMR, and ETAMR is estimated to be ∼0.26 meV.
Modeling of an ionic liquid electrospray using molecular dynamics with constraints
Authors: Borner Arnaud , Li Zheng , Levin Deborah A.
Published: March 2012

Molecular dynamics simulations have been performed to investigate the behavior of the EMIM− BF4 ionic liquid for conditions similar to those of electrospray thrusters. To study the physics of ion extrusion a large system composed of approximately 2160 ion pairs was placed inside a platinum capillary and equilibrated. Diffusion coefficients and electrical conductivity were calculated and compared with literature values, showing good agreement and validating the use of a constrained dynamics model with a coarse-grained potential. An electric field was applied to the system in the longitudinal direction and the fraction of solvated and non-solvated emitted ions was analyzed. The threshold electric field for particle emission was found to be 1.2 V/nm, consistent with other reported work.
Transition properties of a YBa2Cu3O7 nanobridge patterned across a twin boundary of a LaAlO3 substrate
Authors: Hoon Lee Sung , Choi Jae-Huyk , Lee Soon-Gul
Published: March 2012

We have fabricated superconducting YBa2Cu3O7 (YBCO) nanobridges across twin boundaries of LaAlO3 (LAO) substrates by using focused-ion-beam etching and studied their critical transport properties. The nanobridges, nominally 150 nm in width, 100 – 120 nm in length, and 100 nm in thickness, showed Tc = 91 K with ΔTc ≅ 1 K and a high critical current density of Jc ≅ 1.5 × 107 A/cm2 at 77 K. Measured current-voltage curves of YBCO nanobridges across the substrate twin boundary showed resistively-shunted-junction characteristics near the transition with an excess current associated with flux flow. High-resolution X-ray diffraction spectra strongly indicated the possibility that the epitaxially-grown YBCO film was also twinned commensurate with twinning of the LAO substrate. Misorientation of the c-axis of YBCO at the twin boundary is believed to create weaknesses that dictate the behavior of the bridge across the twin boundary.