bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasound estimated fetal weight slightly below the median is associated with increased risk of spontaneous preterm birth
Authors: Severi Filiberto M. , Bocchi Caterina , Imperatore Alberto , Boni Carlotta , Ferrata Chiara , Florio Pasquale , Reis Fernando M. , Petraglia Felice
Published: April 2012

Background

This study investigates the possible relationship between ultrasound estimated fetal weight (EFW) at third trimester and the risk of preterm birth following spontaneous preterm labor in otherwise uncomplicated pregnancies.

Methods

We performed a nested case–control study including 281 cases of spontaneous preterm labor with preterm delivery in the third trimester and 3372 matched controls within a cohort of 6207 consecutive pregnant women. Pregnancies with fetal growth restriction (birth weight <10th centile of population‐based normograms) or fetal anomalies were not included. EFW was calculated by using Hadlock′s formula and converted to fetal gender adjusted multiples of median (MoM) for each gestational age.

Results

EFW correlated with birth weight (r = 0.959, p < 0.0001) and was lower in preterm than in control fetuses (p < 0.0001). The odds ratios (95% confidence intervals) for preterm birth for fetuses below 0.9 MoM, 0.85 MoM, 0.80 MoM, and 0.75 MoM of EFW were, respectively, 4.6 (3.6–5.9), 5.7 (4.3–7.5), 8.5 (5.9–12.1), and 11.2 (6.8–18.3). The independent relationship between preterm birth and lower EFW was confirmed in multivariate analysis with adjustment for potential confounders, such as maternal age, parity, and fetal gender.

Conclusion

In asymptomatic women between 28 and 36 weeks of gestation, an EFW lower than 0.90 MoM increases by 4.6 times the risk of spontaneous preterm birth, and the risk increases proportionally to the degree of weight reduction. © 2012 John Wiley & Sons, Ltd.
Preparation of polyacrylonitrile/graphene oxide by in situ polymerization
Authors: Wu Fangfang , Lu Yonggen , Shao Guilin , Zeng Fanlong , Wu Qilin
Published: April 2012

Highly oriented molecular structure is essential for high‐performance carbon fibers. The addition of a small amount of graphene sheets may enhance the degree of molecular orientation of precursor fibers during spinning and stabilization by limiting the disorientation of the chain segments. Graphene sheets merge into the carbon fiber structure during carbonization. The structure and properties of polyacrylonitrile containing graphene oxide (GO) prepared by in situ polymerization were investigated. With increasing GO loading, the molecular weight of the polymer decreased gradually from 69 000 g mol−1 for the sample without GO to 60 600 g mol−1 for the sample with 2.5 wt% loading of GO. Scanning electron microscopy and X‐ray diffraction results indicated that GO was dispersed in single layers in the polymer matrix. The degree of crystallization of the polymer with 0.5 wt% GO was increased by 8%. Moreover, differential scanning calorimetry and thermogravimetric analysis showed that an appropriate amount of GO, e.g. 0.5 wt%, made the carbon yield of the polymer increase by 5.0 wt%, because the GO in the composite improved the intermolecular crosslinking reaction. Copyright © 2012 Society of Chemical Industry
Superior reinforcement in polyamide 1010/multiwalled carbon nanotube composites realized by high‐rate drawing and incorporation of compatibilizer
Authors: Mai Fang , Zhou Chengjuan , Yao Meijun , Deng Hua , Fu Qiang
Published: April 2012

To realize the full potential of carbon nanotubes (CNTs) in polymer/CNT nanocomposites, many complicated chemical treatments have been developed to modify the CNTs. Nevertheless, the reinforcing efficiency is still not satisfactory in most cases. In this study, a dramatically improved mechanical enhancement is obtained for polyamide 1010/multiwalled carbon nanotube (MWNT) composites simply by exerting high‐rate drawing and incorporating a commercially available compatibilizer. For the fibers prepared at high draw ratio, their tensile strength and modulus are improved by 137 and 132%, respectively, through adding only 0.5 wt% MWNTs. In particular, the increase in strength is at a very high level for the case of non‐covalent interaction since CNTs could be stretched to failure according to theoretical calculation. It is demonstrated that this reinforcement is mainly attributed to the compatibilizer inducing good dispersion, and the high‐rate drawing inducing strong interfacial interaction and orientation of MWNTs. Copyright © 2012 Society of Chemical Industry
Solution structure of the E3 ligase HOIL‐1 Ubl domain
Authors: Beasley Steven A. , Safadi Susan S. , Barber Kathryn R. , Shaw Gary S.
Published: April 2012

The E3 ligases HOIL‐1 and parkin are each comprised of an N‐terminal ubiquitin‐like (Ubl) domain followed by a zinc‐binding region and C‐terminal RING–In‐between‐RING–RING domains. These two proteins, involved in the ubiquitin‐mediated degradation pathway, are the only two known E3 ligases to share this type of multidomain architecture. Further, the Ubl domain of both HOIL‐1 and parkin has been shown to interact with the S5a subunit of the 26S proteasome. The solution structure of the HOIL‐1 Ubl domain was solved using NMR spectroscopy to compare it with that of parkin to determine the structural elements responsible for S5a intermolecular interactions. The final ensemble of 20 structures had a β‐grasp Ubl‐fold with an overall backbone RMSD of 0.59 ± 0.10 Å in the structured regions between I55 and L131. HOIL‐1 had a unique extension of both β1 and β2 sheets compared to parkin and other Ubl domains, a result of a four‐residue insertion in this region. A similar 15‐residue hydrophobic core in the HOIL‐1 Ubl domain resulted in a comparable stability to the parkin Ubl, but significantly lower than that observed for ubiquitin. A comparison with parkin and other Ubl domains indicates that HOIL‐1 likely uses a conserved hydrophobic patch (W58, V102, Y127, Y129) found on the β1 face, the β3–β4 loop and β5, as well as a C‐terminal basic residue (R134) to recruit the S5a subunit as part of the ubiquitin‐mediated proteolysis pathway.
Biochemical and molecular characterisation of acetylcholinesterase in four field populations of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)
Authors: Shen Guang‐Mao , Wang Xiao‐Na , Dou Wei , Wang Jin‐Jun
Published: April 2012

BACKGROUND: The oriental fruit fly, Bactrocera dorsalis, is a major pest that infects fruits and agricultural products worldwide. The latest resistance monitoring of B. dorsalis from mainland China has identified high levels of resistance to insecticides. In this study, the biochemical and molecular characteristics of acetylcholinesterase (AChE) in four field populations of B. dorsalis are investigated.

RESULTS: Among the four populations, the DG population and its purified AChE were found to be the least susceptible to malathion and five inhibitors, whereas the KM population and its purified AChE were the most susceptible. The highest catalytic activity of purified AChE was found for the KM population, and the catalytic activity of the DG population was the lowest. Among developmental stages, the AChE purified from larvae was found to be the most insusceptible to inhibitors, but its catalytic activity was the highest. Sequence analysis of the cDNA encoding AChE showed that some residue differences existed. However, no significant differences in expression levels of the AChE gene among populations and developmental stages were detected.

CONCLUSION: The results suggest that the decrease in susceptibility of B. dorsalis was mainly caused by decrease in AChE activity, and they provide a broad view on the relation between AChE and resistance. Copyright © 2012 Society of Chemical Industry
EPSPS gene amplification in glyphosate‐resistant Italian ryegrass (Lolium perenne ssp. multiflorum) from Arkansas
Authors: Salas Reiofeli A , Dayan Franck E , Pan Zhiqiang , Watson Susan B , Dickson James W , Scott Robert C , Burgos Nilda R
Published: April 2012

BACKGROUND: Resistance to glyphosate in weed species is a major challenge for the sustainability of glyphosate use in crop and non‐crop systems. A glyphosate‐resistant Italian ryegrass population has been identified in Arkansas. This research was conducted to elucidate its resistance mechanism.

RESULTS: The investigation was conducted on resistant and susceptible plants from a population in Desha County, Arkansas (Des03). The amounts of glyphosate that caused 50% overall visual injury were 7 to 13 times greater than those for susceptible plants from the same population. The EPSPS gene did not contain any point mutation that has previously been associated with resistance to glyphosate, nor were there any other mutations on the EPSPS gene unique to the Des03 resistant plants. The resistant plants had 6‐fold higher basal EPSPS enzyme activities than the susceptible plants, but their I50 values in response to glyphosate were similar. The resistant plants contained up to 25 more copies of EPSPS gene than the susceptible plants. The level of resistance to glyphosate correlated with increases in EPSPS enzyme activity and EPSPS copy number.

CONCLUSION: Increased EPSPS gene amplification and EPSPS enzyme activity confer resistance to glyphosate in the Des03 population. This is the first report of EPSPS gene amplification in glyphosate‐resistant Italian ryegrass. Other resistance mechanism(s) may also be involved. Copyright © 2012 Society of Chemical Industry
Benzodiazepines: guide to withdrawing in general practice
Authors: Ferguson Brian
Published: April 2012

Our series on stopping drugs provides practical advice on why, when and how to withdraw drug therapy. Here the author considers the challenges associated with discontinuing benzodiazepines. Copyright © 2012 Wiley Interface Ltd
Local structures and roles of Fe3+ and Cr3+ in p‐type semiconductor CuAlO2
Authors: Huang Dan , Lin Jinru , Nilges Mark J. , Pan Yuanming
Published: April 2012

Single crystals of the p‐type semiconductor CuAlO2, synthesized from the CuO flux method, have been investigated by electron paramagnetic resonance (EPR) spectroscopy at temperatures from 3.5 to 294 K. EPR spectra reveal an axial Cr3+ center and an axial Fe3+ center, presumably arising from impurities in the starting materials. The Cr3+ center at 294 K is characterized by g = 1.979(1) and D = − 7803(3) × 10−4 cm−1. The Fe3+ center at 294 K has g// = 1.9942(1), g⟂ = 1.9964(1), D = 261.9(3) × 10−4 cm−1, $B_{4}^{0} = 4.533(3) \times 10^{- 4} \,{\rm cm}^{- 1} $, and $B_{4}^{3} = 104.23(3) \times 10^{- 4} \,{\rm cm}^{- 1} $. These spin‐Hamiltonian parameters, evaluated by superposition model analyses and periodic density functional theory (DFT) calculations, suggest that both Cr3+ and Fe3+ occupy the Al3+ site but the latter involves distortion related to perturbation from a substitutional Cu+ ion at the nearest Al site. This difference in the local structure between Fe3+ and Cr3+ explains their contrasting effects on the p‐type conductivity in CuAlO2.
Solid‐state formation of ferromagnetic δ‐Mn0.6Ga0.4 thin films with high rotatable uniaxial anisotropy
Authors: Myagkov V. G. , Zhigalov V. S. , Bykova L. E. , Bondarenko G. N. , Mikhlin Yu. L. , Patrin G. S. , Velikanov D. A.
Published: April 2012

Solid‐state reactions in Ga/Mn polycrystalline films of the composition 1 Ga:3 Mn were experimentally investigated. Our X‐ray study showed that the formation of the Ga/Mn → (250 °C) ϕ‐Ga7.7Mn2.3 → (350 °C) δ‐Mn0.6Ga0.4 phase sequence occurs when the annealing temperature is increased to 400 °C. δ‐Mn0.6Ga0.4 samples were found to have high rotatable uniaxial anisotropy. We also showed that magnetic fields with coercivities above H > HC = 8.3 kOe can be used to orient the easy anisotropy axis in any spatial direction while taking the angle of the lag into account.
An Overview of the Applications of Graphene‐Based Materials in Supercapacitors
Authors: Huang Yi , Liang Jiajie , Chen Yongsheng
Published: April 2012

Due to their unique 2D structure and outstanding intrinsic physical properties, such as extraordinarily high electrical conductivity and large surface area, graphene‐based materials exhibit great potential for application in supercapacitors. In this review, the progress made so far for their applications in supercapacitors is reviewed, including electrochemical double‐layer capacitors, pseudo‐capacitors, and asymmetric supercapacitors. Compared with traditional electrode materials, graphene‐based materials show some novel characteristics and mechanisms in the process of energy storage and release. Several key issues for improving the structure of graphene‐based materials and for achieving better capacitor performance, along with the current outlook for the field, are also discussed.
Acculock: accurate and efficient detection of data races
Authors: Xie Xinwei , Xue Jingling , Zhang Jie
Published: April 2012

This paper introduces a new dynamic data race detector, ACCULOCK, to detect data races in Java programs. ACCULOCK is the first hybrid detector that combines lockset and epoch‐based happens‐before for race detection. ACCULOCK analyzes a program execution by reasoning about the subset of the happens‐before relation observed with lock acquires and releases excluded, thereby making it less sensitive to thread interleaving than pure happens‐before detectors. When this relaxed happens‐before relation is violated, ACCULOCK applies a new lockset algorithm to verify the locking discipline by distinguishing reads and writes, thereby making it more immune to false positives than pure lockset detectors. In addition, ACCULOCK is designed to achieve these design objectives by maintaining comparable instrumentation overheads (in both time and space) to that of FASTTRACK, the fastest happens‐before detector available (at least for Java programs). All these properties of ACCULOCK have been validated and confirmed by comparing it against FASTTRACK and five other (pure happens‐before, pure lockset, or hybrid) detectors, which are implemented in the Jikes Research Virtual Machine using a collection of large benchmark programs from a variety of applications. Furthermore, porting ACCULOCK and FASTTRACK to a different platform, RoadRunner, and repeating our experiments yield similar observations in terms of their effectiveness in race detection and instrumentation overheads. Copyright © 2012 John Wiley & Sons, Ltd.
Maxillary brown tumor as initial presentation of parathyroid adenoma: A case report
Authors: Sia Hon‐Ke , Hsieh Ming‐Chia , Yang Li‐Heng , Tu Shih‐Te
Published: April 2012

Brown tumor is a rare late‐stage skeletal change caused by long‐term stimulation of excess parathyroid hormone. It is not neoplastic, but a reparative cellular process. Common sites of brown tumor are the ribs, clavicle, long bones and pelvic girdle. Solitary maxillary brown tumor as initial presentation of primary hyperparathyroidism is rare; it is often accompanied by brown tumors of the other facial bones. Here, we present the first case of solitary maxillary brown tumor in a 29‐year‐old ethnic Chinese woman with initial presentation of a large tumor filling the left maxillary sinus. Underlying long‐standing primary hyperparathyroidism caused by a large parathyroid adenoma was finally diagnosed. Brown tumor tends to be misdiagnosed as malignancy, and delayed diagnosis of the underlying hyperparathyroidism is common. Our case validates the suggestion that young women have a higher probability of brown tumor. Biopsy of the suspicious bone tumor and blood tests for calcium and parathyroid hormone level are crucial and essential to reach the correct diagnosis. Most brown tumors show spontaneous regression after parathyroidectomy. However, direct excision of the brown tumor may be indicated to avoid the risk of facial deformity and orbital compression at a special anatomical site, as in our case.
Morphological aspects of the biological function of the osteocytic lacunar canalicular system and of osteocyte‐derived factors
Authors: Sasakia Muneteru , Hongo Hiromi , Hasegawa Tomoka , Suzuki Reiko , Zhusheng Liu , Luiz de Freitas Paulo Henrique , Yamada Tamaki , Oda Kimimitsu , Yamamoto Tsuneyuki , Li Minqi , Totsuka Yasunori , Amizuka Norio
Published: April 2012

Osteocytes are organized in functional syncytia collectively referred to as the osteocytic lacunar‐canalicular system (OLCS). The osteocytes are interconnected through gap junctions between their cytoplasmic processes, which pass through narrow passageways referred to as osteocytic canaliculi. There are two possible ways molecules can be transported throughout the OLCS: via the cytoplasmic processes and their gap junctions, and via the pericellular space in the osteocytic canaliculi. Transport of minerals and small molecules through a spatially well‐organized OLCS is vital for bone mineral homeostasis, mechanosensing, and bone remodeling control. Recently, osteocyte‐derived molecules – sclerostin, dentin matrix protein‐1, fibroblast growth factor 23 (FGF23) – have been put in evidence as they may be related to osteocytic functions such as mechanosensing, regulation of bone remodeling, and so forth. FGF23 regulates serum phosphate concentration by affecting renal function, while sclerostin can inhibit osteoblastic activities. In our observations, FGF23 and sclerostin synthesis seemed to be associated with the spatial regularity of the OLCS. This review will introduce our recent morphological studies on the regularity of OLCS and the synthesis of osteocyte‐derived FGF23 and sclerostin.
Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations
Authors: Spagnolie Saverio E. , Lauga Eric
Published: April 2012

The swimming trajectories of self-propelled organisms or synthetic devices in a viscous fluid can be altered by hydrodynamic interactions with nearby boundaries. We explore a multipole description of swimming bodies and provide a general framework for studying the fluid-mediated modifications to swimming trajectories. A general axisymmetric swimmer is described as a linear combination of fundamental solutions to the Stokes equations: a Stokeslet dipole, a source dipole, a Stokeslet quadrupole, and a rotlet dipole. The effects of nearby walls or stress-free surfaces on swimming trajectories are described through the contribution of each singularity, and we address the question of how accurately this multipole approach captures the wall effects observed in full numerical solutions of the Stokes equations. The reduced model is used to provide simple but accurate predictions of the wall-induced attraction and pitching dynamics for model Janus particles, ciliated organisms, and bacteria-like polar swimmers. Transitions in attraction and pitching behaviour as functions of body geometry and propulsive mechanism are described. The reduced model may help to explain a number of recent experimental results.
SET IN STONE: HOMELESS CORPSES AND DESECRATED GRAVES IN MODERN IRAN
Authors: Amanat Mehrdad
Published: April 2012

Violence toward corpses and graves, especially the unusual practice of exhuming and burning remains, persisted sporadically through the 20th century in Iran but found new dimensions in the form of mass graves and a systematic desecration of cemeteries in the period following the 1979 Islamic Revolution. This paper seeks to explore the roots of cemetery violence by examining the dynamics of apostasy and the experiences and challenges Babi and Bahaʾi converts faced in their interment practices in the late 19th and early 20th centuries. This period witnessed a significant change in communal identities. Unconventional self-definitions expressed in religious conversions and in fluid or multiple communal affiliations and religious convictions defied traditional boundaries and led to tension between nonconformists and religious authorities. One way for Shiʿi ʿulamaʾ and Jewish rabbis to reassert a conventional center was through the control of cemeteries, including by not allowing converts to be buried in these semisacred spaces.
RESPONSE TO FRED DONNER'S REVIEW OF PARABLE AND POLITICS IN EARLY ISLAMIC HISTORY: THE RASHIDUN CALIPHS (IJMES 43 [2011]: 570–71)
Authors: El-Hibri Tayeb
Published: April 2012

In his recent review of my book, Parable and Politics in Early Islamic History, in the August 2011 issue of IJMES, Fred Donner provides several opinions that are in need of correction. His initial impression that the “basic point of Parable and Politics” follows previous scholarship “in an attempt to work out how much is ‘fact’ and how much is literary invention” (p. 570) sets the wrong tone for evaluating studies on historiography. Far from being merely an opposition between true and false, the study of “fiction” in historiography is actually an analysis of construction not of truthfulness. The complexity of doing this lies in reaching for a multifaceted commentary that was originally intended not only in the individual reports but also through a process of intertextuality, which casts implications on a range of issues and on the representation of characters across a cluster of reports.
Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH
Authors: Mekmene Omar , Rouillon Thierry , Quillard Sophie , Pilet Paul , Bouler Jean-Michel , Pezennec Stéphane , Gaucheron Frédéric
Published: April 2012

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.
Childhood trauma and auditory verbal hallucinations
Authors: Daalman K. , Diederen K. M. J. , Derks E. M. , van Lutterveld R. , Kahn R. S. , Sommer Iris E. C.
Published: April 2012

Background

Hallucinations have consistently been associated with traumatic experiences during childhood. This association appears strongest between physical and sexual abuse and auditory verbal hallucinations (AVH). It remains unclear whether traumatic experiences mainly colour the content of AVH or whether childhood trauma triggers the vulnerability to experience hallucinations in general. In order to investigate the association between hallucinations, childhood trauma and the emotional content of hallucinations, experienced trauma and phenomenology of AVH were investigated in non-psychotic individuals and in patients with a psychotic disorder who hear voices.

Method

A total of 127 non-psychotic individuals with frequent AVH, 124 healthy controls and 100 psychotic patients with AVH were assessed for childhood trauma. Prevalence of childhood trauma was compared between groups and the relation between characteristics of voices, especially emotional valence of content, and childhood trauma was investigated.

Results

Both non-psychotic individuals with AVH and patients with a psychotic disorder and AVH experienced more sexual and emotional abuse compared with the healthy controls. No difference in the prevalence of traumatic experiences could be observed between the two groups experiencing AVH. In addition, no type of childhood trauma could distinguish between positive or negative emotional valence of the voices and associated distress. No correlations were found between sexual abuse and emotional abuse and other AVH characteristics.

Conclusions

These results suggest that sexual and emotional trauma during childhood render a person more vulnerable to experience AVH in general, which can be either positive voices without associated distress or negative voices as part of a psychotic disorder.
Maintenance of permeable habitable subsurface environments by earthquakes and tidal stresses
Authors: Sleep Norman H.
Published: April 2012

Life inhabits the subsurface of the Earth down to depths where temperature precludes it. Similar conditions are likely to exist within the traditional habitable zone for objects between 0.1 Earth mass (Mars) and 10 Earth masses (superearth). Long-term cooling and internal radioactivity maintain surface heat flow on the Earth. These heat sources are comparable and likely to be comparable in general within old rocky planets. Surface heat flow scales with mass divided by surface area and hence with surface gravity. The average absolute habitable subsurface thickness scales inversely with heat flow and gravity. Surface gravity varies by only 0.4 g for Mars to 3.15 g for a superearth. This range is less than the regional variation of heat flow on the Earth. Still ocean-boiling asteroid impacts (if they occur) are more likely to sterilize the thin habitable subsurface of large objects than thick habitable subsurface of small ones. Tectonics self-organizes to maintain subsurface permeability and habitability within both stable and active regions on the Earth. Small earthquakes within stable regions allow sudden mixing of water masses. Large earthquakes at plate boundaries allow surface water to descend to great habitable depths. Seismic shaking near major faults cracks shallow rock forming permeable regolith. Strong tidal strains form a similar porous regolith on small bodies such as Enceladus with weak stellar heating. This regolith may be water-saturated within rocky bodies and thus habitable.
Relative dispersion observations and trajectory modeling in the Santa Barbara Channel
Authors: Ohlmann J. Carter , LaCasce Joe H. , Washburn Libe , Mariano Arthur J. , Emery Brian
Published: April 2012

Relative dispersion statistics and related Lagrangian parameters, not well observed in coastal regions, are obtained from in situ surface drifter observations and presented in the context of Lagrangian stochastic models. Clusters of GPS tracked surface drifters, with initial horizontal spacing of 5–10 m, were repetitively deployed in the Santa Barbara Channel from July 2004 to June 2005. The drifters sampled their position every 10 min for 1–2 days. Mean square pair separation distance, or relative dispersion, increases approximately exponentially in time during the first ∼5 h of sampling (e‐folding time of 0.9 h). Thereafter, the dispersion increase is approximately quadratic in time. Large error bars on the observed mean dispersion, and higher‐order Lagrangian statistics that are not clearly supportive of the aforementioned dispersion curves, indicate uncertainty. The mean square relative (separation) velocity shows near‐linear growth with pair separation distance, extending from 0.3 to 85 cm2 s−2over length scales from ∼8 m to 2.2 km. The observed length scale dependency in square relative velocity is investigated in a Lagrangian stochastic model (LSM) for a cloud of particles. Modeled dispersion agrees with observations only when the velocity scale for the sub‐grid scale random normal deviate in the LSM (typically a constant) is length scale dependent, and takes into consideration the observed scaling. Occasional large (>25 cm s−1) discrepancies in grid‐scale velocities between drifters and HF radar cause general disagreement in distributions of ending positions of LSM trajectories when compared with Lagrangian observations.
A hydrophilic/hydrophobic organic (H2O) aerosol model: Development, evaluation and sensitivity analysis
Authors: Couvidat Florian , Debry Édouard , Sartelet Karine , Seigneur Christian
Published: April 2012

A secondary organic aerosol (SOA) model, the Hydrophilic/Hydrophobic Organic model (H2O), is presented and evaluated over Europe. H2O uses surrogate organic molecules to represent the myriad of SOA species and distinguishes two kinds of surrogate species: hydrophilic species (which condense preferentially into an aqueous phase) and hydrophobic species (which condense only into an organic phase). These surrogate species are formed from the oxidation in the atmosphere of volatile organic compounds. H2O includes several important processes, including the effect of nitrogen oxides (NOX) on SOA formation, the dissociation of organic acids in an aqueous phase, the oligomerization of aldehydes, the non‐ideality of the particle phase and the hygroscopicity of organics. Concentrations of organic aerosols were simulated over Europe from July 2002 to July 2003 for comparison with measurements of the European Monitoring Evaluation Program (EMEP). In H2O, primary organic aerosols (POA) are considered as semi‐volatile organic compounds (SVOC) present in both the gas phase and the particle phase. Taking into account the gas‐phase fraction of SVOC increases significantly organic PM concentrations, particularly in winter, in better agreement with observations. The impacts on organic aerosol formation of ideality, of the choice of the parameterization for isoprene SOA formation, and of the OM/OC ratio of the model were also investigated. Assuming ideality in H2O was found to lead to a small decrease in OM. Compared to a two‐product parameterization, the parameterization of Couvidat and Seigneur [2011] for SOA formation from isoprene oxidation leads to a significant increase in isoprene SOA by taking into account their hydrophilic properties and suggests that most models may currently underestimate isoprene SOA.
Intercomparing hillslope hydrological dynamics: Spatio‐temporal variability and vegetation cover effects
Authors: Bachmair S. , Weiler M. , Troch P. A.
Published: April 2012

Generalizable process knowledge on hillslope hydrological dynamics is still very poor, yet indispensable for numerous theoretical and practical applications. To gain insight into the organization of hillslope hydrological dynamics we intercompared 90 observations of shallow water table dynamics at three neighboring large‐scale (33 × 75 m) hillslopes with similar slope, aspect, curvature, geologic, and pedologic properties but differences in vegetation cover (grassland, coniferous forest, and mixed forest) over a time period of 9 months. High‐resolution measurements of water table fluctuations, rainfall, and discharge in the creek at the foot of all hillslopes allowed a good system characterization. The aim of this study was to explore the spatio‐temporal variability of water table fluctuations within and between hillslopes, the effect of event and antecedent characteristics on the observed dynamics, and how the hillslope subsurface flow (SSF) response is reflected in the runoff response. To intercompare the SSF behavior we conducted an event‐based analysis of the percentage of well activation, several metrics characterizing the shape and timing of the water table response curves, rainfall characteristics, antecedent wetness conditions, and several runoff response metrics. The analysis reveals that there are distinct differences in SSF response between the grassland hillslope and the forested hillslopes, with a lower frequency of well activation and absolute water table rise at the grassland hillslope. Second, spatial patterns of water table dynamics differ between wet fall/winter/spring (predominantly saturation of the lower part of the hillslope, weaker water table response, and slower response times) and dry summer conditions (whole‐hillslope activation but higher spatial variability, generally stronger water table dynamics, and quicker response times). The observed seasonally changing water table dynamics suggest the development of a preferential flow network during high‐intensity rainstorms under dry summer conditions. Third, catchment runoff is strongly driven by hillslope dynamics, yet contrasting hydrographs during events with similar hillslope dynamics indicate the influence of additional processes. Overall, the observed high spatio‐temporal variability of seemingly homogeneous hillslopes calls for rethinking of current monitoring strategies and developing and testing new conceptual models of hillslope hydrologic processes.
Improving understanding of geomagnetic substorms
Authors: Balcerak Ernie
Published: April 2012

Substorms, the frequent, brief magnetic disturbances that originate in Earth's magnetotail, cause acceleration of particles in the magnetosphere and their precipitation into the ionosphere, resulting in sudden brightening and increased movement and expansion of aurorae. Sergeev et al. review recent progress that has been made in understanding the onset and dynamics of substorms. In particular, recent observations have confirmed that magnetic reconnection—the breaking up and rejoining of magnetic field lines and release of energy—in the Earth's magnetotail, which sends fast plasma streams into the inner magnetosphere, is closely associated with substorm onset. Large‐scale reconfiguration of the magnetic fields in the magnetotail and local instabilities interact in complex ways, leading to the onset of substorms.
The paradox of cooling streams in a warming world: Regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States
Authors: Arismendi Ivan , Johnson Sherri L. , Dunham Jason B. , Haggerty Roy , Hockman‐Wert David
Published: April 2012

Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream temperature. Here, we examined the evidence for this using long‐term stream temperature data from minimally and highly human‐impacted sites located across the Pacific continental United States. Based on hypothesized climate impacts, we predicted that we should find warming trends in the maximum, mean and minimum temperatures, as well as increasing variability over time. These predictions were not fully realized. Warming trends were most prevalent in a small subset of locations with longer time series beginning in the 1950s. More recent series of observations (1987–2009) exhibited fewer warming trends and more cooling trends in both minimally and highly human‐influenced systems. Trends in variability were much less evident, regardless of the length of time series. Based on these findings, we conclude that our perspective of climate impacts on stream temperatures is clouded considerably by a lack of long‐term data on minimally impacted streams, and biased spatio‐temporal representation of existing time series. Overall our results highlight the need to develop more mechanistic, process‐based understanding of linkages between climate change, other human impacts and stream temperature, and to deploy sensor networks that will provide better information on trends in stream temperatures in the future.
The Prevalence of Obesity‐Related Hypertension and Risk for New Vascular Events in Patients With Vascular Diseases
Authors: Vernooij Joris W.P. , Van der Graaf Yolanda , Visseren Frank L.J. , Spiering Wilko ,   On behalf of the SMART study group
Published: April 2012

Higher body weight is associated with an increased prevalence of vascular risk factors. Obesity leads to hypertension by various mechanisms, often referred to as obesity‐related hypertension. Aim of the present study was to evaluate the prevalence and the vascular risk of the combination of obesity and hypertension in patients with vascular diseases. A cohort of patients with various clinical manifest vascular diseases (n = 4,868) was screened for vascular risk factors and followed (median follow‐up 4.2 years) for the occurrence of vascular events (stroke, myocardial infarction, and vascular death). The prevalence of obesity was 18% (95% confidence interval (CI) 17–19%) and the prevalence of hypertension was 83% (95% CI 82–84%). The prevalence of the combination of obesity and hypertension was 16% (95% CI 15–17%). Patients with high blood pressure (BP) combined with a high weight (highest tertile systolic BP (SBP) in the highest tertile BMI) were not at higher risk for new vascular events (hazard ratios (HR) 1.29; 95% CI 0.89–1.88) or mortality (HR 1.18; 95% CI 0.81–1.73) compared to patients without high BP and high weight (patients in the lowest tertile of SBP in the lowest tertile of BMI). Patients with only high weight did not have an elevated risk either for vascular events (HR 1.34; 95% CI 0.91–1.98) or mortality (HR 1.22; 95% CI 0.81–1.83) compared to patients without high BP and high weight. The prevalence of the combination of hypertension and obesity is low in patients with vascular diseases and does not confer a higher risk for recurrent vascular diseases and mortality than each risk factor alone.
Bright Start: Description and Main Outcomes From a Group‐Randomized Obesity Prevention Trial in American Indian Children
Authors: Story Mary , Hannan Peter J. , Fulkerson Jayne A. , Rock Bonnie Holy , Smyth Mary , Arcan Chrisa , Himes John H.
Published: April 2012

The aim of the Bright Start study was to develop and test the effectiveness of a school environment intervention, supplemented with family involvement, to reduce excessive weight gain by increasing physical activity and healthy eating practices among kindergarten and first‐grade American Indian children. Bright Start was a group‐randomized, school‐based trial involving 454 children attending 14 schools on the Pine Ridge Reservation in South Dakota. Children were followed from the beginning of their kindergarten year through the end of first grade. Main outcome variables were mean BMI, mean percent body fat, and prevalence of overweight/obese children. The goals of the intervention were to: increase physical activity at school to at least 60 min/day; modify school meals and snacks; and involve families in making behavioral and environmental changes at home. At baseline, 32% of boys and 25% of girls were overweight/obese. Although the intervention was not associated with statistically significant change in mean levels of BMI, BMI‐Z, skinfolds or percentage body fat, the intervention was associated with a statistically significant net decrease of 10% in the prevalence of overweight. Intervention children experienced a 13.4% incidence of overweight, whereas the control children experienced a corresponding incidence of 24.8%; a difference of −11.4% (P = 0.033). The intervention significantly reduced parent‐reported mean child intakes of sugar‐sweetened beverages, whole milk, and chocolate milk. Changes in duration of school physical activity were not significant. Because obesity is the most daunting health challenge facing American Indian children today, more intervention research is needed to identify effective approaches.
Epithelial–mesenchymal interaction during UVB-induced up-regulation of neutral endopeptidase
Authors: Nakajima Hiroaki , Ezaki Yoshiyuki , Nagai Tomoyashu , Yoshioka Ryosuke , Imokawa Genji
Published: April 2012

We recently reported that overexpression of the elastase NEP (neutral endopeptidase) by fibroblasts plays a pivotal role in the mechanism of UVB-induced skin wrinkling by degrading dermal elastic fibres. Since UVB does not penetrate to the dermis, we hypothesized that factors secreted by UVB-exposed keratinocytes in the epidermis trigger fibroblasts in the dermis to increase their expression of NEP which then degrades the elastic fibres. In the present study, we characterized the epithelial–mesenchymal interaction between keratinocytes and fibroblasts which leads to increased expression of NEP. Human fibroblasts co-cultured with UVB-exposed human keratinocytes in cell inserts significantly increased their expression of NEP at the transcriptional, translational and enzymatic levels. Neutralizing antibodies to IL (interleukin)-1α or GM-CSF (granulocyte/macrophage colony-stimulating factor) significantly abolished the increased expression of NEP at the enzymatic levels in human fibroblasts co-cultured with UVB-exposed human keratinocytes, whereas neutralizing antibodies to IL-6, IL-8 or TNFα (tumour necrosis factor α) had no such effect. The addition of IL-1α or GM-CSF, but not TNFα, IL-6 or IL-8, at concentrations ranging from 1 to 10 nM, significantly stimulated the expression of NEP in human fibroblasts at the transcriptional and translational levels. These findings suggest that IL-1α and GM-CSF are intrinsic cytokines secreted by UVB-exposed keratinocytes that stimulate expression of NEP by fibroblasts.
Conformational dynamics and thermodynamics of protein–ligand binding studied by NMR relaxation
Authors: Akke Mikael
Published: April 2012

Protein conformational dynamics can be critical for ligand binding in two ways that relate to kinetics and thermodynamics respectively. First, conformational transitions between different substates can control access to the binding site (kinetics). Secondly, differences between free and ligand-bound states in their conformational fluctuations contribute to the entropy of ligand binding (thermodynamics). In the present paper, I focus on the second topic, summarizing our recent results on the role of conformational entropy in ligand binding to Gal3C (the carbohydrate-recognition domain of galectin-3). NMR relaxation experiments provide a unique probe of conformational entropy by characterizing bond-vector fluctuations at atomic resolution. By monitoring differences between the free and ligand-bound states in their backbone and side chain order parameters, we have estimated the contributions from conformational entropy to the free energy of binding. Overall, the conformational entropy of Gal3C increases upon ligand binding, thereby contributing favourably to the binding affinity. Comparisons with the results from isothermal titration calorimetry indicate that the conformational entropy is comparable in magnitude to the enthalpy of binding. Furthermore, there are significant differences in the dynamic response to binding of different ligands, despite the fact that the protein structure is virtually identical in the different protein–ligand complexes. Thus both affinity and specificity of ligand binding to Gal3C appear to depend in part on subtle differences in the conformational fluctuations that reflect the complex interplay between structure, dynamics and ligand interactions.
The oxysterol-binding protein superfamily: new concepts and old proteins
Authors: Villasmil Michelle L. , Bankaitis Vytas A. , Mousley Carl J.
Published: April 2012

The Kes1 OSBP (oxysterol-binding protein) is a key regulator of membrane trafficking through the TGN (trans-Golgi network) and endosomal membranes. We demonstrated recently that Kes1 acts as a sterol-regulated rheostat for TGN/endosomal phosphatidylinositol 4-phosphate signalling. Kes1 utilizes its dual lipid-binding activities to integrate endosomal lipid metabolism with TORC1 (target of rapamycin complex 1)-dependent proliferative pathways and transcriptional control of nutrient signalling.
Intrinsic rotation with gyrokinetic models
Authors: Parra Felix I. , Barnes Michael , Calvo Iván , Catto Peter J.
Published: April 2012

The generation of intrinsic rotation by turbulence and neoclassical effects in tokamaks is considered. To obtain the complex dependences observed in experiments, it is necessary to have a model of the radial flux of momentum that redistributes the momentum within the tokamak in the absence of a preexisting velocity. When the lowest order gyrokinetic formulation is used, a symmetry of the model precludes this possibility, making small effects in the gyroradius over scale length expansion necessary. These effects that are usually small become important for momentum transport because the symmetry of the lowest order gyrokinetic formulation leads to the cancellation of the lowest order momentum flux. The accuracy to which the gyrokinetic equation needs to be obtained to retain all the physically relevant effects is discussed.
Finite-time stochastic combination synchronization of three different chaotic systems and its application in secure communication
Authors: Runzi Luo , Yinglan Wang
Published: April 2012

In this paper, the finite-time stochastic combination synchronization of three different chaotic systems is investigated. Based on the adaptive technique and the properties of Weiner process, a novel sufficient condition is obtained to ensure combination synchronization under stochastic perturbations. Moreover, a secure communication scheme based on the adaptive combination synchronization of three different systems, i.e., the Lorenz system, Chen system, and Lü system, with uncertainties, unknown parameters, and stochastic perturbation is presented. The simulation results show the feasibility of the proposed method.
Spin pumping and spin filtering in double quantum dots with time-dependent spin-orbit interactions
Authors: Pan Hui , Zhao Yinghui
Published: April 2012

We propose a scheme of realizing both spin pumping and spin filtering in a double quantum dot with homogeneous Zeeman splittings in the presence of oscillating spin-orbit interactions. We find that a spin-polarized pumping current can be achieved by tuning the relative energies of the Zeeman-split levels of the dots. It is also found that a pure spin current can be generated at zero detuning, whose magnitude can be modulated by the external fields. At a certain constellation of system parameters, the pumping current can become almost fully spin-polarized. Therefore, it is possible to select a particular spin component of the current to be pumped from the left to the right lead. We finally give some discussions on the realization of the spin pumping and spin filtering effects.
Imaging of subatomic electron cloud interactions: Effect of higher harmonics processing in noncontact atomic force microscopy
Authors: Alan Wright C. , Solares Santiago D.
Published: April 2012

In a previous study of higher harmonics atomic force microscopy imaging of graphite using a tungsten tip [Hembacher et al., Science 305, 380 (2004)], the authors interpreted the observed subatomic features as the signature of tip apex electron bonding lobes. We explore here their higher harmonics processing and filtering methods. We do not find any imaging artifacts inherent to the filtering process, but we find that the harmonics averaging approach used is not appropriate due to non-uniform harmonics ratios across the surface. A promising alternative may be the individual mapping of the first two harmonics.
Seebeck coefficient of a quantum confined, high-electron-density electron gas in SrTiO3
Authors: Cain Tyler A. , Lee SungBin , Moetakef Pouya , Balents Leon , Stemmer Susanne , James Allen S.
Published: April 2012

We report on the Seebeck coefficient of quantum confined electron gases in GdTiO3/SrTiO3 heterostructures. These structures contain two-dimensional electron gases with very high sheet-carrier concentrations on the SrTiO3-side of the interface due to intrinsic interface doping. While the sheet carrier concentrations are independent of the thickness of the SrTiO3 layer, the Seebeck coefficient initially increases with SrTiO3 thickness before saturating at a value of ∼300 μK/V. A model of the Seebeck coefficient, based on thermally populated, self-consistent, tight binding subbands, captures in a semi-quantitative manner the observed thickness dependence.