bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing North Atlantic weather patterns for climate‐optimal aircraft routing
Authors: Irvine Emma A. , Hoskins Brian J. , Shine Keith P. , Lunnon Robert W. , Froemming Christine
Published: January 2012

Daily weather patterns over the North Atlantic are classified into relevant types: typical weather patterns that may characterize the range of climate impacts from aviation in this region, for both summer and winter. The motivation is to provide a set of weather types to facilitate an investigation of climate‐optimal aircraft routing of trans‐Atlantic flights (minimizing the climate impact on a flight‐by‐flight basis). Using the New York to London route as an example, the time‐optimal route times are shown to vary by over 60 min, to take advantage of strong tailwinds or avoid headwinds, and for eastbound routes latitude correlates well with the latitude of the jet stream. The weather patterns are classified by their similarity to the North Atlantic Oscillation and East Atlantic teleconnection patterns. For winter, five types are defined; in summer, when there is less variation in jet latitude, only three types are defined. The types can be characterized by the jet strength and position, and therefore the location of the time‐optimal routes varies by type. Simple proxies for the climate impact of carbon dioxide, ozone, water vapour and contrails are defined, which depend on parameters such as the route time, latitude and season, the time spent flying in the stratosphere, and the distance over which the air is supersaturated with respect to ice. These proxies are then shown to vary between weather types and between eastbound and westbound routes. Copyright © 2012 Royal Meteorological Society
Linear and Nonlinear Support Vector Machine for the Classification of Human 5‐HT1A Ligand Functionality
Authors: Wang Lirong , Ma Chao , Wipf Peter , Xie Xiang‐Qun
Published: January 2012

Upon binding to a receptor, agonists and antagonists can induce distinct biological functions and thus lead to significantly different pharmacological responses. Thus, in silico prediction or in vitro characterization of ligand agonistic or antagonistic functionalities is an important step toward identifying specific pharmacological therapeutics. In this study, we investigated the molecular properties of agonists and antagonists of human 5‐hydroxytryptamine receptor subtype 1A (5‐HT1A). Subsequently, intrinsic functions of these ligands (agonists/antagonists) were modeled by support vector machine (SVM), using five 2D molecular fingerprints and the 3D Topomer distance. Five kernel functions, including linear, polynomial, RBF, Tanimoto and a novel Topomer kernel based on Topomer 3D similarity were used to develop linear and nonlinear classifiers. These classifiers were validated through cross‐validation, yielding a classification accuracy ranging from 80.4 % to 92.3 %. The performance of different kernels and fingerprints was analyzed and discussed. Linear and nonlinear models were further interpreted through the illustration of underlying classification mechanism. The computation protocol has been automated and demonstrated through our online service. This study expands the scope and applicability of similarity‐based methods in cheminformatics, which are typically used for the identification of active molecules against a target protein. Our findings provide a good starting point for further systematic classifications of other GPCR ligands and for the data mining of large chemical libraries.
Keyhole chemical exchange saturation transfer
Authors: Varma G. , Lenkinski R. E. , Vinogradov E.
Published: January 2012

The keyhole technique, which involves the acquisition of dynamic data at low resolution in combination with a high‐resolution reference, is developed for the purposes of chemical exchange saturation transfer (CEST) imaging, i.e., Keyhole CEST. Low‐resolution data are acquired with saturation applied at different frequencies for Z‐spectra, along with a high‐resolution reference image taken without saturation. Three methods for high‐resolution reconstruction of Keyhole CEST are evaluated using the values from quantitative high‐resolution CEST maps. In addition, Keyhole CEST is applied for collection of data used for B0 correction. The keyhole approach is evaluated for CEST contrast generation using exchanging protons in hydroxyl groups. First, the techniques are evaluated in vitro using samples of dextrose and chondroitin sulfate. Next, the work is extended in vivo to explore its applicability for gagCEST. Comparable quantitative gagCEST values are found using Keyhole CEST, provided the structure or region of interest is not limited by the low‐resolution dataset. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Volumetric navigators for real‐time motion correction in diffusion tensor imaging
Authors: Alhamud A. , Tisdall M. Dylan , Hess Aaron T. , Hasan Khader M. , Meintjes Ernesta M. , van der Kouwe André J.W.
Published: January 2012

Prospective motion correction methods using an optical system, diffusion‐weighted prospective acquisition correction, or a free induction decay navigator have recently been applied to correct for motion in diffusion tensor imaging. These methods have some limitations and drawbacks. This article describes a novel technique using a three‐dimensional‐echo planar imaging navigator, of which the contrast is independent of the b‐value, to perform prospective motion correction in diffusion weighted images, without having to reacquire volumes during which motion occurred, unless motion exceeded some preset thresholds. Water phantom and human brain data were acquired using the standard and navigated diffusion sequences, and the mean and whole brain histogram of the fractional anisotropy and mean diffusivity were analyzed. Our results show that adding the navigator does not influence the diffusion sequence. With head motion, the whole brain histogram‐fractional anisotropy shows a shift toward lower anisotropy with a significant decrease in both the mean fractional anisotropy and the fractional anisotropy histogram peak location (P < 0.01), whereas the whole brain histogram‐mean diffusivity shows a shift toward higher diffusivity with a significant increase in the mean diffusivity (P < 0.01), even after retrospective motion correction. These changes in the mean and the shape of the histograms are recovered substantially in the prospective motion corrected data acquired using the navigated sequence. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
B1 mapping with selective pulses
Authors: Bouhrara Mustapha , Bonny Jean‐Marie
Published: January 2012

Knowledge of B distribution is crucial for many applications, such as quantitative MRI. A novel method has been developed to improve the accuracy of the conventionally applied double‐angle method for B mapping. It solves the remaining issues raised by the use of selective pulses for slice selection to accelerate the acquisition process. A general approach for reconstructing B maps is presented first. It takes B‐induced slice profile distortions over off‐resonance frequencies into account. It is then shown how the ratio between the prescribed flip angles can be adjusted to reach a compromise between the level of noise propagated onto B maps and the width of the range in which the field can be mapped. Lastly, several solutions are proposed for reducing the B‐dependent pollution of regions distal to the image slice which participates significantly in the inaccuracy of B mapping. These methods were experimentally tested by comparison with gold standard B maps obtained on a phantom using a non‐selective and thus much slower technique. As they are independent and lead to significant improvements, these solutions can be combined to achieve high precision and fast B mapping using spin‐echo DAM. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Early in vivo MR spectroscopy findings in organophosphate‐induced brain damage—potential biomarkers for short‐term survival
Authors: Shrot Shai , Anaby Debbie , Krivoy Amir , Makarovsky Igor , Rosman Yossi , Bloch‐Shilderman Eugenia , Lazar Shlomi , Bar‐shir Amnon , Cohen Yoram
Published: January 2012

Organophosphates are highly toxic substances, which cause severe brain damage. The hallmark of the brain injury is major convulsions. The goal of this study was to assess the spatial and temporal MR changes in the brain of paraoxon intoxicated rats. T2‐weighted MRI and 1H‐MR‐spectroscopy were conducted before intoxication, 3 h, 24 h, and 8 days postintoxication. T2 prolongation mainly in the thalami and cortex was evident as early as 3 h after intoxication (4–6% increase in T2 values, P < 0.05). On spectroscopy,
N‐acetyl aspartate (NAA)/creatine and NAA/choline levels significantly decreased 3 h postintoxication (>20% decrease, P < 0.005), and 3 h lactate peak was evident in all intoxicated animals. On the 8th day, although very little T2 changes were evident, NAA/creatine and choline/creatine were significantly decreased (>15%, P < 0.05). Animals who succumbed had extensive cortical edema, significant higher lactate levels and a significant decrease in NAA/creatine and NAA/choline levels compared to animals which survived the experiment. Organophosphates‐induced brain damage is obvious on MR data already 3 h postintoxication. In vivo spectroscopic changes are more sensitive for assessing long‐term injury than T2‐weighted MR imaging. Early spectroscopic findings might be used as biomarkers for the severity of the intoxication and might predict early survival. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Element agglomeration coarse Raviart–Thomas spaces with improved approximation properties
Authors: Lashuk I.V. , Vassilevski P.S.
Published: January 2012

We propose a new technique based on element agglomeration for constructing coarse subspaces of the lowest‐order tetrahedral Raviart–Thomas finite element space. The coarse spaces are spanned by local basis functions associated with each coarse face (i.e., with an interface between two agglomerated elements). Each such face is associated with up to four coarse basis functions. The support of these functions extends into the neighboring agglomerated elements, and the construction of these functions involves solution of certain local mixed finite element problem on each neighboring agglomerated element. In contrast to some previous work, the thus constructed coarse subspace exhibits improved approximation properties because under certain conditions, it locally contains (i.e., interpolates exactly) all vector constants. Our construction is general; in particular, we do not assume that the coarse faces are planar. Possible applications of the coarse Raviart–Thomas spaces are in constructing multigrid methods for the H(div) bilinear forms and (on the basis of the approximation properties of these spaces) in upscaling of mixed formulation of diffusion problems. Copyright © 2012 John Wiley & Sons, Ltd.
Facile design of biomaterials by ‘click’ chemistry
Authors: Hvilsted Søren
Published: January 2012

The advent of the so‐called ‘click chemistry’ a decade ago has significantly improved the chemical toolbox for producing novel biomaterials. This review focuses primarily on the application of Cu(I)‐catalysed azide–alkyne 1,3‐cycloadditon in the preparation of numerous, diverse biomaterials and biomedical materials and concepts. In addition, the thiol–ene ‘click’ reaction is addressed in the same manner, and the possibility of using both click reactions orthogonally is highlighted. A strategy for the preparation of novel intriguing poly(ε‐caprolactone)‐based nanobiomaterials by orthogonal click chemistry is elaborated. The present state of creating functional and biologically active surfaces by click chemistry is presented. Finally, conducting surfaces based on an azide‐functionalized polymer with prospective biological sensor potential are introduced. Copyright © 2012 Society of Chemical Industry
Chromium distribution in multicrystalline silicon: comparison of simulations and experiments
Authors: Schön Jonas , Habenicht Holger , Warta Wilhelm , Schubert Martin C.
Published: January 2012

We studied the precipitation of chromium in multicrystalline silicon during the crystallization process and temperature treatments typical for solar cell processing. A model which was already successfully used for simulating heterogeneous precipitation of iron is transferred to chromium, allowing two‐dimensional simulations of dissolved chromium and precipitate density. The observed accordance with spatially resolved measurements demonstrates the similarity of chromium to iron precipitation and the ability of our model to predict the dissolved chromium concentration in multicrystalline silicon. After the crystallization process, a high impact of chromium on the carrier lifetime of wafers originating from an ingot intentionally contaminated with 20 ppma chromium in the melt was observed. The concentration of dissolved chromium was significantly reduced by phosphorus diffusion gettering or oxidation at 815°C. Copyright © 2012 John Wiley & Sons, Ltd.
Dissecting cell death with proteomic scalpels
Authors: Wang Li‐Shun , Xia Li , Shen Shao‐Min , Zheng Ying , Yu Yun , Chen Guo‐Qiang
Published: January 2012

Programmed cell deaths (PCD), including apoptosis, autophagy and programmed necrosis, are genetically determined, complex processes in multi‐cellular organisms. Problems with the regulation of PCD have been implicated in a number of diseases including myocardial infarction, cancer and autoimmune disease. As a result, the investigation on PCD regulation has stirred considerable interest. In the past decades, many PCD‐involved proteins had been identified as being modulated by post‐translational mechanisms, including post‐translational modification, protein‐protein interactions and protein cleavage, which fall precisely within the range of proteomic analysis. Contemporary quantitative proteomics, interactomics, PTMomics, degradomics, chemical proteomics and pharmacoproteomics have been quickly applied in the field of PCD research, and possess the potential to be the driving forces of the field. This review attempts to highlight some of the major achievements in the application of proteomics in PCD research to trigger further thinking and application.
10‐GHz 4.69‐W/mm InAlN/GaN HFET on sapphire substrate
Authors: Feng Zhihong , Liu Bo , Yin Jiayun , Wang Jinjin , Gu Guodong , Dun Shaobo , Cai Shujun
Published: January 2012

A high‐performance InAlN/GaN heterojunction ﬁeld effect transistor with a nominal gate length of 0.25 μm was fabricated on a sapphire substrate. Low defect density and low sheet resistance were obtained for the heterostructure under tests. The fabricated device exhibited a negligible current collapse, and remarkable RF characteristics, i.e. a maximum output power density of 4.69 W/mm at 10 GHz, a linear gain of 11.8 dB, and a peak power‐added efﬁciency of 48%, suggesting the extraordinary performances reachable by InAlN based technology. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry characterization of aging effects on the mineral fibers treated with aminopropylsilane and quaternary ammonium compounds
Authors: Zafar A. , Schjødt‐Thomsen J. , Sodhi R. , Goacher R. , de Kubber D.
Published: January 2012

X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry were used to investigate the aging effects on the aminopropylsilane (APS) and quaternary ammonium surfactant‐treated mineral fibers. APS‐coated mineral fiber samples were treated with cationic surfactant and mineral oil and aged at 70 °C temperature and 95% humidity. From quantitative XPS measurements, an increase in the atomic composition of oxygen, nitrogen, and silicon is observed after aging. An increase in the protonated amino groups in the N1s high‐resolution spectra and C–N group in the C1s high‐resolution spectra is also observed. These results indicate that the concentration of hydrocarbon groups decreases after aging due to the partial removal of the long hydrocarbon chains of the surfactant and mineral oil and/or hydrolysis and segregation of APS to the fiber surface. The principal component analysis (PCA) was applied to the time‐of‐flight secondary ion mass spectrometry spectra, and an increase in the intensities of APS characteristic peaks were observed after aging. The observed increase in the signals of APS originates from underlying silanized fibers after the removal of the surfactant and mineral oil from the surface. Copyright © 2012 John Wiley & Sons, Ltd.
Extended X‐Ray Absorption Fine Structure Investigation of Annealed Carbon Expanded Austenite
Authors: Oddershede Jette , Christiansen Thomas L. , Ståhl Kenny , Somers Marcel A. J.
Published: January 2012

Carbon expanded austenite synthesized through carburizing of austenitic stainless steel powder at 380°C was annealed at 470°C and investigated with extended X‐ray absorption fine structure (EXAFS) and synchrotron powder diffraction (SPD). SPD showed that the samples consisted of carbon expanded austenite and Hägg carbide, χ‐M5C2. EXAFS showed that the Cr atoms were mainly present in environments similar to the carbides Hägg χ‐M5C2 and M23C6. The environments of the Fe and Ni atoms were concluded to be largely metallic austenite.
Canopy characteristics affect reproductive success of golden‐cheeked warblers
Authors: Klassen Jessica A. , Morrison Michael L. , Mathewson Heather A. , Rosenthal Gil G. , Wilkins R. Neal
Published: January 2012

The golden‐cheeked warbler (Setophaga chrysoparia), listed by the U.S. Fish and Wildlife Service as endangered in 1990 due primarily to habitat loss and fragmentation, is a Neotropical migrant songbird that breeds exclusively in mature juniper–oak (Juniperus–Quercus) woodlands in central Texas, USA. Previous studies suggested suitable breeding habitat consists of >35% canopy closure (with 50–70% cover optimal), and ≥10% oak composition. However, little is known about this species' habitat relationships at the southwestern edge of its breeding range. Therefore, within this portion of the species' breeding range, we investigated influences of canopy closure and tree species composition on pairing and reproductive success of golden‐cheeked warblers during 2009 and 2010. We used remote sensing and ground sampling to acquire variables to describe habitat characteristics, and we estimated pairing for breeding and reproductive success by golden‐cheeked warblers. We found successfully breeding pairs in areas with >20% canopy cover, 35% juniper composition, and only 3% oak composition. A logistic model for pairing success retained juniper, oak, and the interaction between these 2 variables, and the model for reproductive success retained juniper, canopy closure, study area, and the interaction between canopy closure and study area. Our results expand our knowledge of habitat conditions that warblers use for breeding, thus expanding the range of habitat management options available for this species during breeding season. © 2012 The Wildlife Society.
Amputation du gland après circoncision
Authors: Mseddi M. A. , Chabchoub K. , Bouasida M. , Rebai N. , Hadjslimen M. , Bahloul A. , Mhiri M. N.
Published: January 2012

Introduction

Sous nos climats, la circoncision reste l’intervention la plus couramment pratiquée chez le garçon. Elle est souvent réalisée par un personnel paramédical non qualifié, ou même en dehors du milieu médical dont les notions de chirurgie et d’asepsie sont aléatoires. Elle est réputée comme chirurgie bénigne, mais des complications majeures parfois très graves, engageant le pronostic sexuel, voire vital, peuvent survenir. Le but de ce travail était de rapporter les amputations du gland secondaires à la circoncision et reçues en milieu hospitalier urologique.

Patients et méthode

Nous rapportons huit cas d’amputation du gland suite à une circoncision en milieu extrahospitalier selon les méthodes traditionnelles.

Résultats

L’âge moyen des enfants est de six ans (trois à huit ans). L’amputation du gland était faite lors de la circoncision dans quatre cas, dont deux avec section complète. Dans les autres cas, il s’agissait d’une nécrose du gland à cause d’un arc électrique lors de l’utilisation inadéquate du bistouri électrique. Une reconstruction urgente du gland n’avait pu être réalisable que dans trois cas. Le gland sectionné dans le quatrième cas était de mauvaise qualité. On n’a noté qu’un seul succès de revascularisation du gland. Le délai de consultation en cas de nécrose du gland était de trois jours en moyenne. Le traitement n’avait consisté qu’en la réalisation d’une méatoplastie pour obtenir un méat urétral satisfaisant avec réfection de la peau pénienne.

Conclusion

La section du gland demeure une complication, certes rare de la circoncision mais très grave, engageant le pronostic sexuel ultérieur de l’enfant. Cela rend cette intervention non anodine et doit inciter à ne la réaliser qu’en milieu spécialisé par un personnel compétent.
Methicillin-resistant Infection after Hip and Knee Replacement: Reason to Change Practice?
Authors: Van Houwelingen Andrew P. , Garbuz Donald S. , Masri Bassam A. , Duncan Clive P.
Published: January 2012

Infection after a primary total-joint replacement can be devastating. If the infecting organism is meth-icillin resistant, the chance of successful eradication of the infection is considerably decreased. What is more concerning is that these organisms are becoming increasingly common in periprosthetic joint infection. We have reviewed the literature and have outlined the effectiveness of single- and two-stage treatment regimens for this difficult problem. We have also looked at the screening and decolonisation methods that have been implemented in an attempt to decrease the risk of surgical site infections. Lastly, we outline our recommendations on how we should tackle this emerging and difficult problem that is affecting the orthopaedic world.
Aktive Gesundheitsförderung bei älteren Menschen - Erfahrungen aus dem Kinzigtal
Authors: Mnich Eva , Hofreuter-Götgens Kerstin , Knesebeck Olaf von dem
Published: January 2012

Einleitung

Das Programm „Aktive Gesundheitsförderung im Alter“ (AGil) zielt auf Veränderungen in den Bereichen körperliche Aktivität, Ernährung und soziale Teilhabe. Das bereits in einem städtischen Kontext (Hamburg) erfolgreiche Programm wurde im ländlichen Raum (Kinzigtal) erprobt. Für die Prozessevaluation wurden die Zielgruppenerreichung, die Akzeptanz, förderliche und hemmende Faktoren der Durchführung sowie die Transferierbarkeit des Programms untersucht. Gegenstand der Ergebnisevaluation war ein Vorher-Nachher-Vergleich im Hinblick auf Zielbereiche der Intervention und den Gesundheitszustand.
A randomized study comparing plasma concentration of ropivacaine after local infiltration analgesia and femoral block in primary total knee arthroplasty
Authors: Affas Fatin , Stiller Carl-Olav , Nygårds Eva-Britt , Stephanson Niclas , Wretenberg Per , Olofsson Christina
Published: January 2012

Pain after total knee arthroplasty (TKA) is difficult to control. A recently developed and increasingly popular method for postoperative analgesia following knee and hip arthroplasty is Local Infiltration Analgesia (LIA) with ropivacaine, ketorolac and epinephrine. This method is considered to have certain advantages, which include administration at the site of traumatized tissue, minimal systemic side effects, faster postoperative mobilization, earlier postoperative discharge from hospital and less opioid consumption. One limitation, which may prevent the widespread use of LIA is the lack of information regarding plasma concentrations of ropivacaine and ketorolac.

The aim of this academically initiated study was to detect any toxic or near-toxic plasma concentrations of ropivacaine and ketorolac following LIA after TKA.

Methods

Forty patients scheduled for primary total knee arthroplasty under spinal anaesthesia, were randomized to receive either local infiltration analgesia with a mixture of ropivacaine 300 mg, ketorolac 30mg and epinephrine or repeated femoral nerve block with ropivacaine in combination with three doses of 10mg intravenous ketorolac according to clinical routine. Plasma concentration of ropivacaine and ketorolac were quantified by liquid chromatography–mass spectrometry (LC–MS).

Results

The maximal detected ropivacaine plasma level in the LIA group was not statistically higher than in the femoral block group using the Mann–Whitney U-test (p = 0.08). However, the median concentration in the LIA group was significantly higher than in the femoral block group (p < 0.0001; Mann–Whitney U-test).

The maximal plasma concentrations of ketorolac following administration of 30mg according to the LIA protocol were detected 1 h or 2 h after release of the tourniquet in the LIA group: 152–958 ng/ml (95% CI: 303–512 ng/ml; n = 20). The range of the plasma concentration of ketorolac 2–3 h after injection of a single dose of 10mg was 57–1216 ng/ml (95% CI: 162–420 ng/ml; n = 20).

Conclusion

During the first 24 h plasma concentration of ropivacaine seems to be lower after repeated femoral block than after LIA. Since the maximal ropivacaine level following LIA is detected around 4–6 h after release of the tourniquet, cardiac monitoring should cover this interval. Regarding ketorolac, our preliminary data indicate that the risk for concentration dependent side effects may be highest during the first hours after release of the tourniquet.

Implication

Femoral block may be the preferred method for postoperative analgesia in patients with increased risk for cardiac side effects from ropivacaine. Administration of a booster dose of ketorolac shortly after termination of the surgical procedure if LIA was used may result in an increased risk for toxicity.
Transcranial direct current stimulation in the treatment of major depression: a meta-analysis
Authors: Kalu U. G. , Sexton C. E. , Loo C. K. , Ebmeier K. P.
Published: January 2012

Background

So far, no comprehensive answer has emerged to the question of whether transcranial direct current stimulation (tDCS) can make a clinically useful contribution to the treatment of major depression. We aim to present a systematic review and meta-analysis of tDCS in the treatment of depression.

Method

Medline and Embase were searched for open-label and randomized controlled trials of tDCS in depression using the expressions (‘transcranial direct current stimulation’ or ‘tDCS’) and (‘depression’ or ‘depressed’). Study data were extracted with a standardized data sheet. For randomized controlled trials, effect size (Hedges' g) was calculated and the relationships between study variables and effect size explored using meta-regression.

Results

A total of 108 citations were screened and 10 studies included in the systematic review. Six randomized controlled trials were included in the meta-analysis, with a cumulative sample of 96 active and 80 sham tDCS courses. Active tDCS was found to be more effective than sham tDCS for the reduction of depression severity (Hedges' g=0.743, 95% confidence interval 0.21–1.27), although study results differed more than expected by chance (Q=15.52, df=6, p=0.017, I2=61.35). Meta-regression did not reveal any significant correlations.

Conclusions

Our study was limited by the small number of studies included, which often had small sample size. Future studies should use larger, if possible representative, health service patient samples, and optimized protocols to evaluate the efficacy of tDCS in the treatment of depression further.
Mechanism for export of sediment‐derived iron in an upwelling regime
Authors: Siedlecki S. A. , Mahadevan A. , Archer D. E.
Published: January 2012

Model simulations performed with a three‐dimensional, high‐resolution, process study ocean model of eastern boundary upwelling systems are used to describe a mechanism that efficiently transports sediment‐derived dissolved iron offshore in the subsurface through the bottom boundary layer (BBL) during downwelling‐favorable wind events. In the model, sediment‐derived iron accumulates in the BBL on the outer shelf when the winds are upwelling‐favorable. When the wind reverses, the iron‐laden BBL is mixed into the water column and transported offshore along isopycnals that intersect the bottom. Depending on the frequency of wind reversal, between 10–50% of the shelf sediment‐derived iron flux is exported offshore through this previously unidentified subsurface pathway. If this mechanism operates on all coastal upwelling regimes, the global export of sediment‐derived iron to the open ocean would be equivalent to ten times larger than the estimated source of dissolved iron from aerosols.
Evidence for 13‐carbon enrichment in oxalic acid via iron catalyzed photolysis in aqueous phase
Authors: Pavuluri Chandra Mouli , Kawamura Kimitaka
Published: January 2012

To investigate the effect of photochemical aging on the stable carbon isotopic ratio (δ13C) of oxalic acid (OxA), a dominant organic species in atmospheric aerosols, we conducted a laboratory photolysis of OxA under H2O2‐Fe3+(Fe2+)‐UV system in aqueous phase and measuredδ13C of remaining OxA. Our results showed that a significant photolysis of OxA occurred with OH radical but the isotopic fractionation of OxA was insignificant. In contrast, in the presence of Fe3+ (Fe2+), we found a significant enrichment of 13C in remaining OxA. We also found that kinetic isotope effect (KIE) of OxA largely depends on photochemical age (irradiation time) and concentration ratios of OxA to iron; 3.20 ± 0.49‰ (2.18 ± 1.18‰) and 21.62 ± 5.41‰ in 90 min and 180 min irradiation, in which OxA and Fe3+ (Fe2+) ratios were 50:1 and 200:1, respectively. The enrichment of 13C in remaining OxA was more significant during the photolysis catalyzed by Fe3+ (7‰) than by Fe2+ (3‰) in 90 min irradiation when OxA and iron ratios are the same (50:1). This study provides a laboratory evidence for the isotopic enrichment of 13C in OxA with photochemical aging. This approach is useful for better interpretation of atmospheric isotopic measurements in terms of the extent of atmospheric processing of aerosols.
Experimental constraints on the outgassing dynamics of basaltic magmas
Authors: Pioli L. , Bonadonna C. , Azzopardi B. J. , Phillips J. C. , Ripepe M.
Published: January 2012

The dynamics of separated two‐phase flow of basaltic magmas in cylindrical conduits has been explored combining large‐scale experiments and theoretical studies. Experiments consisted of the continuous injection of air into water or glucose syrup in a 0.24 m diameter, 6.5 m long bubble column. The model calculates vesicularity and pressure gradient for a range of gas superficial velocities (volume flow rates/pipe area, 10−2–102 m/s), conduit diameters (100–2 m), and magma viscosities (3–300 Pa s). The model is calibrated with the experimental results to extrapolate key flow parameters such as Co (distribution parameter) and Froude number, which control the maximum vesicularity of the magma in the column, and the gas rise speed of gas slugs. It predicts that magma vesicularity increases with increasing gas volume flow rate and decreases with increasing conduit diameter, until a threshold value (45 vol.%), which characterizes churn and annular flow regimes. Transition to annular flow regimes is expected to occur at minimum gas volume flow rates of 103–104 m3/s. The vertical pressure gradient decreases with increasing gas flow rates and is controlled by magma vesicularity (in bubbly flows) or the length and spacing of gas slugs. This study also shows that until conditions for separated flow are met, increases in magma viscosity favor stability of slug flow over bubbly flow but suggests coexistence between gas slugs and small bubbles, which contribute to a small fraction of the total gas outflux. Gas flow promotes effective convection of the liquid, favoring magma homogeneity and stable conditions.
High resolution three‐dimensional X‐ray diffraction study of dislocations in grains of MgGeO3 post‐perovskite at 90 GPa
Authors: Nisr Carole , Ribárik Gábor , Ungár Tamás , Vaughan Gavin B. M. , Cordier Patrick , Merkel Sébastien
Published: January 2012

MgGeO3 post‐perovskite (pPv) is a lower pressure analogue of MgSiO3‐pPv, which is believed to be the main constituent of the Earth's D″ layer. Understanding the physical properties of this phase is critical to explain seismological observations as seismic anisotropy is likely linked to lattice preferred orientation in post‐perovskite, which is governed by the motion of defects such as dislocations. Here, we apply in‐situ three‐dimensional X‐ray diffraction to a polycrystalline sample of MgGeO3‐pPv at 90 GPa. We demonstrate how the method can be used to follow individual grains within the material, including their individual orientations, positions, and strain tensors. We then use X‐ray line profile analysis to characterize dislocations in the grains. The most probable slip systems are
〈110〉 gliding on
or (001) and [110](001), with a smaller contribution of [100](001) and [001] dislocations. These slip systems are shown to be consistent with observations of seismic anisotropy in D″.
What influence will future solar activity changes over the 21st century have on projected global near‐surface temperature changes?
Authors: Jones Gareth S. , Lockwood Mike , Stott Peter A.
Published: January 2012

During the 20th century, solar activity increased in magnitude to a so‐called grand maximum. It is probable that this high level of solar activity is at or near its end. It is of great interest whether any future reduction in solar activity could have a significant impact on climate that could partially offset the projected anthropogenic warming. Observations and reconstructions of solar activity over the last 9000 years are used as a constraint on possible future variations to produce probability distributions of total solar irradiance over the next 100 years. Using this information, with a simple climate model, we present results of the potential implications for future projections of climate on decadal to multidecadal timescales. Using one of the most recent reconstructions of historic total solar irradiance, the likely reduction in the warming by 2100 is found to be between 0.06 and 0.1 K, a very small fraction of the projected anthropogenic warming. However, if past total solar irradiance variations are larger and climate models substantially underestimate the response to solar variations, then there is a potential for a reduction in solar activity to mitigate a small proportion of the future warming, a scenario we cannot totally rule out. While the Sun is not expected to provide substantial delays in the time to reach critical temperature thresholds, any small delays it might provide are likely to be greater for lower anthropogenic emissions scenarios than for higher‐emissions scenarios.
Evaluation of the Transfer Coefficient Matrix (TCM) approach to model the atmospheric radionuclide air concentrations from Fukushima
Authors: Draxler Roland R. , Rolph Glenn D.
Published: January 2012

A procedure is developed and tested to provide operational plume forecasts in real‐time by continuously updating the previous day's simulations as new meteorological data become available. Simulations are divided into smaller time segments and each segment is continued as an independent calculation using a unit source emission. Multiple computational species are tracked at the same time to represent different classes of radionuclides, each with different dry and wet deposition characteristics. When quantitative air concentration results are required, the unit source calculations are multiplied by the appropriate temporally varying emission rates and decay factors for the radionuclide species involved. Air concentrations for multiple emission scenarios can easily be created in a few minutes and used to optimize model results as more measurement data become available. The procedure was evaluated for the Fukushima accident using publically available emission estimates and some I‐131 and Cs‐137 monitoring data. The model performance was evaluated at four sampling locations (Dutch Harbor, Alaska; Seattle, Washington; Dublin, Ireland; and Huelva, Spain) at various distances from Japan. The model results showed a very high correlation for the I‐131 particulate predictions (0.94) and a moderate correlation for the Cs‐137 predictions (0.40). The cesium predictions at Seattle showed five distinct time periods of concentration over‐predictions associated with two peak emission periods. Adjusting these emission rates downward to correspond more closely with the time‐adjacent rates eliminated the over‐prediction but resulted in total emissions of Cs‐137 (3 PBq) that were much less than estimated by other researchers (36 PBq).
Experimental investigation of the thermal dispersivity term and its significance in the heat transport equation for flow in sediments
Authors: Rau Gabriel C. , Andersen Martin S. , Acworth R. Ian
Published: January 2012

A review of heat and solute transport in sediments demonstrates that the use of heat as a tracer has not been experimentally evaluated under the same experimental conditions as those used for the evaluation of solute as a tracer. Furthermore, there appears to be disagreement in the earth science literature over the significance of the thermal dispersivity term. To help resolve this disagreement, detailed experimentation with typical groundwater flow velocities (Darcy range, Re < 2.5) was conducted in a specifically designed hydraulic tank containing well‐sorted saturated sand. The experiment enabled, for the first time, the precise monitoring of heat and solute tracer movement from a point source in separate runs under identical solid matrix and steady state flow conditions. Experimental results demonstrate that heat transport with natural groundwater flow velocities can reach a transition zone between conduction and convection (0.5 < Pet < 2.5). The thermal dispersion behavior can be described by using a thermal dispersivity coefficient and the square of the thermal front velocity. We propose an empirical formulation for thermal dispersion with Darcy flow in natural porous media and clarify the disagreement regarding its significance. Finally, it was observed that Darcy velocities independently derived from heat and solute experimentation show a systematic discrepancy of up to 20%, and that experimental thermal dispersion results contain significant scatter.
Application of ground‐penetrating radar to measure near‐saturation soil water content in peat soils
Authors: Parsekian Andrew D. , Slater Lee , Giménez Daniel
Published: January 2012

The presence and flux of biogenic methane‐rich free phase gas that is eventually released to the atmosphere influence water content (θ) of peat soils below the water table. Small variations in gas content in peat soils at near‐saturation θ could be inferred by changes in dielectric permittivity, but detailed measurements in that range of θ needed to develop calibration functions are lacking. Our experiment uses a new method for varying θ in the sample using elevated pressure to reduce the naturally occurring volumetric gas content in a manner similar to what occurs in situ under atmospheric pressure change, which relevant to understanding carbon gas cycling in peatlands. We recorded dielectric permittivity using a 1.6 MHz ground‐penetrating radar antenna at multiple water contents between 0.87 and 0.95 m3 m−3 on four peat monoliths with varying levels of humification and with <5% gas content as is commonly observed in the field. We identified empirical equations that were linear over the range of θ investigated and optimized a dielectric mixing model for estimating θ from GPR. These results indicate that there are differences in the permittivity‐θ relationships developed between peat samples and suggest that variability in dielectric relationships may be attributed to peat structure and particle orientation. The empirical relationships developed in this study confirm the utility of previously applied multiphase mixing models for estimating peat properties using methods sensitive to dielectric permittivity. This work is relevant to studies of gas content in peat and the role of peatlands in the carbon cycle.
Inside an unquiet mind
Authors: Critchlow Hanna M , Herrington Paul , Gunton Simon
Published: January 2012

Both art and science have the power to challenge preconceptions. Neuroscientists, healthcare professionals and service users came together in 2011 to dramatize the scientific and societal issues surrounding mental ill health.
Regulation of TOR by small GTPases
Authors: Durán Raúl V , Hall Michael N
Published: January 2012

TOR is a conserved serine/threonine kinase that responds to nutrients, growth factors, the bioenergetic status of the cell and cellular stress to control growth, metabolism and ageing. A diverse group of small GTPases including Rheb, Rag, Rac1, RalA and Ryh1 play a variety of roles in the regulation of TOR. For example, while Rheb binds to and activates TOR directly, Rag and Rac1 regulate its localization and RalA activates it indirectly through the production of phosphatidic acid. Here, we review recent findings on the regulation of TOR by small GTPases.
Dinitrogen fixation in a unicellular chlorophyll d-containing cyanobacterium
Authors: Pfreundt Ulrike , Stal Lucas J , Voß Björn , Hess Wolfgang R
Published: January 2012

Marine cyanobacteria of the genus Acaryochloris are the only known organisms that use chlorophyll d as a photosynthetic pigment. However, based on chemical sediment analyses, chlorophyll d has been recognized to be widespread in oceanic and lacustrine environments. Therefore it is highly relevant to understand the genetic basis for different physiologies and possible niche adaptation in this genus. Here we show that unlike all other known isolates of Acaryochloris, the strain HICR111A, isolated from waters around Heron Island, Great Barrier Reef, possesses a unique genomic region containing all the genes for the structural and enzymatically active proteins of nitrogen fixation and cofactor biosynthesis. Their phylogenetic analysis suggests a close relation to nitrogen fixation genes from certain other marine cyanobacteria. We show that nitrogen fixation in Acaryochloris sp. HICR111A is regulated in a light–dark-dependent fashion. We conclude that nitrogen fixation, one of the most complex physiological traits known in bacteria, might be transferred among oceanic microbes by horizontal gene transfer more often than anticipated so far. Our data show that the two powerful processes of oxygenic photosynthesis and nitrogen fixation co-occur in one and the same cell also in this branch of marine microbes and characterize Acaryochloris as a physiologically versatile inhabitant of an ecological niche, which is primarily driven by the absorption of far-red light.
Unraveling assembly of stream biofilm communities
Authors: Besemer Katharina , Peter Hannes , Logue Jürg B , Langenheder Silke , Lindström Eva S , Tranvik Lars J , Battin Tom J
Published: January 2012

Microbial biofilms assemble from cells that attach to a surface, where they develop into matrix-enclosed communities. Mechanistic insights into community assembly are crucial to better understand the functioning of natural biofilms, which drive key ecosystem processes in numerous aquatic habitats. We studied the role of the suspended microbial community as the source of the biofilm community in three streams using terminal-restriction fragment length polymorphism and 454 pyrosequencing of the 16S ribosomal RNA (rRNA) and the 16S rRNA gene (as a measure for the active and the bulk community, respectively). Diversity was consistently lower in the biofilm communities than in the suspended stream water communities. We propose that the higher diversity in the suspended communities is supported by continuous inflow from various sources within the catchment. Community composition clearly differed between biofilms and suspended communities, whereas biofilm communities were similar in all three streams. This suggests that biofilm assembly did not simply reflect differences in the source communities, but that certain microbial groups from the source community proliferate in the biofilm. We compared the biofilm communities with random samples of the respective community suspended in the stream water. This analysis confirmed that stochastic dispersal from the source community was unlikely to shape the observed community composition of the biofilms, in support of species sorting as a major biofilm assembly mechanism. Bulk and active populations generated comparable patterns of community composition in the biofilms and the suspended communities, which suggests similar assembly controls on these populations.
First evidence for the existence of pennate diatom viruses
Authors: Tomaru Yuji , Toyoda Kensuke , Kimura Kei , Hata Naotsugu , Yoshida Mikihide , Nagasaki Keizo
Published: January 2012

Diatoms are considered the most successful and widespread group of photosynthetic eukaryotes. Their contribution to primary production is remarkably significant to the earth's ecosystems. Diatoms are composed of two orders: Centrales and Pennales. Thus far, viruses infecting centric diatom species have been isolated and characterized; however, viruses infecting pennates have not been reported. Here, we describe the first isolations and preliminary characterizations of two distinct pennate diatom viruses, AglaRNAV (31 nm in diameter, accumulates in the host cytoplasm) and TnitDNAV (35 nm in diameter, accumulates in the host nuclei) infecting Asterionellopsis glacialis and Thalassionema nitzschioides, respectively. Their genomes contain a single-stranded RNA of approximately 9.5 kb, and a closed, circular single-stranded DNA of approximately 5.5 kb harboring a partially double-stranded region, respectively. Further analysis of these viruses may elucidate many aspects of diatom host–virus relationships.
The Effects of Reality Television on Weight Bias: An Examination of The Biggest Loser
Authors: Domoff Sarah E. , Hinman Nova G. , Koball Afton M. , Storfer‐Isser Amy , Carhart Victoria L. , Baik Kyoung D. , Carels Robert A.
Published: January 2012

Weight‐loss reality shows, a popular form of television programming, portray obese individuals and their struggles to lose weight. While the media is believed to reinforce obesity stereotypes and contribute to weight stigma, it is not yet known whether weight‐loss reality shows have any effect on weight bias. The goal of this investigation was to examine how exposure to 40‐min of The Biggest Loser impacted participants' levels of weight bias. Fifty‐nine participants (majority of whom were white females) were randomly assigned to either an experimental (one episode of The Biggest Loser) or control (one episode of a nature reality show) condition. Levels of weight bias were measured by the Implicit Associations Test (IAT), the Obese Person Trait Survey (OPTS), and the Anti‐fat Attitudes scale (AFA) at baseline and following the episode viewing (1 week later). Participants in The Biggest Loser condition had significantly higher levels of dislike of overweight individuals and more strongly believed that weight is controllable after the exposure. No significant condition effects were found for implicit bias or traits associated with obese persons. Exploratory analyses examining moderation of the condition effect by BMI and intention to lose weight indicated that participants who had lower BMIs and were not trying to lose weight had significantly higher levels of dislike of overweight individuals following exposure to The Biggest Loser compared to similar participants in the control condition. These results indicate that anti‐fat attitudes increase after brief exposure to weight‐loss reality television.