bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐latitude Pi2 oscillations observed by polar Low Earth Orbiting satellite
Authors: Thomas Neethal , Vichare Geeta , Sinha A. K. , Rawat Rahul 
Published: August 2015

AbstractLow‐latitude Pi2 pulsations in the topside ionosphere are investigated using vector magnetic field measurements from LEO satellite, CHAMP, and underneath ground station. Substorm‐associated Pi2s are initially identified using high‐resolution data from Indian station Shillong, during 2007–2009, and are further classified into three subgroups of Pi2 band (6–25 mHz), based on its frequency. During nighttime, coherent in‐phase oscillations are observed in the compressional component at satellite and horizontal component at underneath ground station for all the Pi2 events, irrespective of the Pi2 frequency. We observe that the identification of daytime Pi2s at CHAMP (compressional component) depends on the frequency of Pi2 oscillation; i.e., 40%, 45%, and 100% of Pi2 events observed in dayside ground station with frequency between 6–10 mHz, 10–15 mHz, and 15–25 mHz were identified at satellite, respectively. At CHAMP during daytime, the presence of a dominant power in the lower frequencies of Pi2 band, which is unique to satellite, is consistently observed and can modify the Pi2 oscillations. Pi2s having frequency >15 mHz are less affected by these background frequencies, and a clear signature of daytime Pi2s at CHAMP is possible to observe, provided that contribution from non‐Pi2 frequencies at satellite from the lower end of Pi2 band is eliminated. Daytime Pi2s identified in the topside ionosphere showed coherent but mostly opposite phase oscillations with underneath ground station, and satellite‐to‐ground amplitude ratio is, in general, found to be less than 1. Present results indicate that a combination of fast cavity‐mode oscillations and an instantaneous transmission of Pi2 electric field from high‐ to low‐latitude ionosphere is responsible for the observation of daytime Pi2s.
Coevolution of bed surface patchiness and channel morphology: 1. Mechanisms of forced patch formation
Authors: Nelson Peter A. , McDonald Richard R. , Nelson Jonathan M. , Dietrich William E. 
Published: August 2015

AbstractRiverbeds frequently display a spatial structure where the sediment mixture composing the channel bed has been sorted into discrete patches of similar grain size. Even though patches are a fundamental feature in gravel bed rivers, we have little understanding of how patches form, evolve, and interact. Here we present a two‐dimensional morphodynamic model that is used to examine in greater detail the mechanisms responsible for the development of forced bed surface patches and the coevolution of bed morphology and bed surface patchiness. The model computes the depth‐averaged channel hydrodynamics, mixed‐grain‐size sediment transport, and bed evolution by coupling the river morphodynamic model Flow and Sediment Transport with Morphological Evolution of Channels (FaSTMECH) with a transport relation for gravel mixtures and the mixed‐grain‐size Exner equation using the active layer assumption. To test the model, we use it to simulate a flume experiment in which the bed developed a sequence of alternate bars and temporally and spatially persistent forced patches with a general pattern of coarse bar tops and fine pools. Cross‐stream sediment flux causes sediment to be exported off of bars and imported into pools at a rate that balances downstream gradients in the streamwise sediment transport rate, allowing quasi‐steady bar‐pool topography to persist. The relative importance of lateral gravitational forces on the cross‐stream component of sediment transport is a primary control on the amplitude of the bars. Because boundary shear stress declines as flow shoals over the bars, the lateral sediment transport is increasingly size selective and leads to the development of coarse bar tops and fine pools.
A new approach to modeling aerosol effects on East Asian climate: Parametric uncertainties associated with emissions, cloud microphysics, and their interactions
Authors: Yan Huiping , Qian Yun , Zhao Chun , Wang Hailong , Wang Minghuai , Yang Ben , Liu Xiaohong , Fu Qiang 
Published: August 2015

AbstractIn this study, we adopt a parametric sensitivity analysis framework that integrates the quasi‐Monte Carlo parameter sampling approach and a surrogate model to examine aerosol effects on the East Asian Monsoon climate simulated in the Community Atmosphere Model (CAM5). A total number of 256 CAM5 simulations are conducted to quantify the model responses to the uncertain parameters associated with cloud microphysics parameterizations and aerosol (e.g., sulfate, black carbon (BC), and dust) emission factors and their interactions. Results show that the interaction terms among parameters are important for quantifying the sensitivity of fields of interest, especially precipitation, to the parameters. The relative importance of cloud microphysics parameters and emission factors (strength) depends on evaluation metrics or the model fields we focused on, and the presence of uncertainty in cloud microphysics imposes an additional challenge in quantifying the impact of aerosols on cloud and climate. Due to their different optical and microphysical properties and spatial distributions, sulfate, BC, and dust aerosols have very different impacts on East Asian Monsoon through aerosol‐cloud‐radiation interactions. The climatic effects of aerosol do not always have a monotonic response to the change of emission factors. The spatial patterns of both sign and magnitude of aerosol‐induced changes in radiative fluxes, cloud, and precipitation could be different, depending on the aerosol types, when parameters are sampled in different ranges of values. We also identify the different cloud microphysical parameters that show the most significant impact on climatic effect induced by sulfate, BC, and dust, respectively, in East Asia.
Discussion of paper ‘Seismic behavior and modeling of steel reinforced concrete (SRC) walls’ by Xiaodong Ji, Ya Sun, Jiaru Qian and Xinzheng Lu, Earthquake Engineering and Structural Dynamics 2015; 44(6):955–972
Authors: Yuksel S. Bahadir 
Published: August 2015

SummaryThe paper under discussion presents a series of quasi‐static tests used to examine the behavior of steel reinforced concrete (SRC) walls subjected to high axial force and lateral cyclic loading. A total of six wall specimens were designed, including five SRC walls and one reinforced concrete (RC) wall. In the ‘Summary’ section of the discussed paper, the authors state that: ‘The use of SRC walls has gained popularity in the construction of high‐rise buildings because of their superior performance over conventional RC walls’. The authors also proposed that, the SRC wall specimens showed increased flexural strength and deformation capacity relative to their RC wall counterpart. The discussion is prompted to rectify some statements and conclusions of the paper under discussion. Copyright © 2015 John Wiley & Sons, Ltd.
Effects of a Specialist-Led, School Physical Education Program on Bone Mass, Structure, and Strength in Primary School Children: A 4-Year Cluster Randomized Controlled Trial
Authors: Daly Robin M , Ducher Gaele , Hill Briony , Telford Rohan M , Eser Prisca , Naughton Geraldine , Seibel Markus J , Telford Richard D 
Published: August 2015

ABSTRACT

This 4-year cluster randomized controlled trial of 365 boys and 362 girls (mean age 8.1 ± 0.3 years) from grade 2 in 29 primary schools investigated the effects of a specialist-taught physical education (PE) program on bone strength and body composition. All children received 150 min/week of common practice (CP) PE from general classroom teachers but in 13 schools 100 min/week of CP PE was replaced by specialized-led PE (SPE) by teachers who emphasized more vigorous exercise/games combined with static and dynamic postural activities involving muscle strength. Outcome measures assessed in grades 2, 4, and 6 included: total body bone mineral content (BMC), lean mass (LM), and fat mass (FM) by DXA, and radius and tibia (4% and 66% sites) bone structure, volumetric density and strength, and muscle cross-sectional area (CSA) by pQCT. After 4-years, gains in total body BMC, FM, and muscle CSA were similar between the groups in both sexes, but girls in the SPE group experienced a greater gain in total body LM (mean 1.0 kg; 95% CI, 0.2 to 1.9 kg). Compared to CP, girls in the SPE group also had greater gains in cortical area (CoA) and cortical thickness (CoTh) at the mid-tibia (CoA, 5.0% [95% CI, 0.2% to 1.9%]; CoTh, 7.5% [95% CI, 2.4% to 12.6%]) and mid-radius (CoA, 9.3% [95% CI, 3.5% to 15.1%]; CoTh, 14.4% [95% CI, 6.1% to 22.7%]), whereas SPE boys had a 5.2% (95% CI, 0.4% to 10.0%) greater gain in mid-tibia CoTh. These benefits were due to reduced endocortical expansion. There were no significant benefits of SPE on total bone area, cortical density or bone strength at the mid-shaft sites, nor any appreciable effects at the distal skeletal sites. This study indicates that a specialist-led school-based PE program improves cortical bone structure, due to reduced endocortical expansion. This finding challenges the notion that periosteal apposition is the predominant response of bone to loading during the prepubertal and early-pubertal period. © 2015 American Society for Bone and Mineral Research.
Molecular simulations study of novel 1,4‐dihydropyridines derivatives with a high selectivity for Cav3.1 calcium channel
Authors: Liu Xiaoguang , Yu Hui , Zhao Xi , Huang Xu‐Ri 
Published: August 2015

Abstract1,4‐Dihydropyridines (DHPs) have been developed to treat hypertension, angina, and nerve system disease. They are thought to mainly target the L‐type calcium channels, but low selectivity prompts them to block Cav1.2 and Cav3.1 channels simultaneously. Recently, some novel DHPs with different hydrophobic groups have been synthesized and among them M12 has a higher selectivity for Cav3.1. However, the structural information about Cav3.1‐DHPs complexes is not available in the experiment. Thus, we combined homology modeling, molecular docking, molecular dynamics simulations, and binding free energy calculations to quantitatively elucidate the inhibition mechanism of DHPs. The calculated results indicate that our model is in excellent agreement with experimental results. On the basis of conformational analysis, we identify the main interactions between DHPs and calcium channels and further elaborate on the different selectivity of ligands from the micro perspective. In conjunction with energy distribution, we propose that the binding sites of Cav3.1‐DHPs is characterized by several interspersed hydrophobic amino acid residues on the IIIS6 and IVS6 segments. We also speculate the favorable function groups on prospective DHPs. Besides, our model provides important information for further mutagenesis experiments.
Low Vitamin D Levels in Children with Fractures: A Comparative Cohort Study
Authors: Fabricant Peter D. , Dy Christopher J. , McLaren Son H. , Rauck Ryan C. , Ipp Lisa S. , Doyle Shevaun M. 
Published: August 2015

Background The currently accepted ranges for “normal” serum vitamin D have recently been challenged in adults on the basis that healthy bone metabolism requires higher levels of vitamin D than previously thought. Purpose The purpose of this study was to evaluate whether a new “biologically based” classification based on 25(OH)vitamin D levels that invoke an endocrine biomarker response (<20 ng/mL for deficiency and <32 ng/mL for insufficiency) is more appropriate for children with fractures than historical criteria. Methods Serum 25(OH)vitamin D levels were collected from 58 children with acute low-energy fractures from an outpatient orthopedic clinic from 2009 to 2012. These vitamin D levels were compared with a cohort of 103 children with chronic kidney disease (CKD) from an adjacent clinic, a condition with acknowledged low levels of vitamin D. Then, the prevalence of vitamin D sufficiency in the fracture cohort was evaluated and compared using both historical guidelines and newer biologically based criteria. Results 25(OH)vitamin D levels in the fracture cohort did not differ from levels in the CKD cohort (27.5 vs. 24.6 ng/mL) indicating a similar distribution of vitamin D levels. This finding was consistent when controlling for significant covariables using linear regression analyses. In the fracture cohort, there was a discrepancy between historical and biologically based criteria in 64% of children. Conclusions The results of the current study suggest that fracture patients are more frequently vitamin D deficient than previously thought. This finding is more readily apparent when newer biologically based criteria for vitamin D sufficiency are used.
Dust Plate, Retina, Photograph: Imaging on Experimental Surfaces in Early Nineteenth-Century Physics
Authors: Ramalingam Chitra 
Published: August 2015

ArgumentThis article explores the entangled histories of three imaging techniques in early nineteenth-century British physical science, techniques in which a dynamic event (such as a sound vibration or an electric spark) was made to leave behind a fixed trace on a sensitive surface. Three categories of “sensitive surface” are examined in turn: first, a metal plate covered in fine dust; second, the retina of the human eye; and finally, a surface covered with a light-sensitive chemical emulsion (a photographic plate). For physicists Michael Faraday and Charles Wheatstone, and photographic pioneer William Henry Fox Talbot, transient phenomena could be studied through careful observation and manipulation of the patterns wrought on these different surfaces, and through an understanding of how the imaging process unfolded through time. This exposes the often-ignored materiality and temporality of epistemic practices around nineteenth-century scientific images said to be “drawn by nature.”
Dietary effects on the formation of dolichyl monophosphate mannose by microsomal preparations of rat adipose tissue
Authors: Lucas John J. , Tepperman Helen , Tepperman Jay 
Published: August 2015

Microsomal preparations from rat adipose tissue catalyse the transfer of [14C]mannose from GDP-[14C]mannose to an endogenous acceptor forming a [14C]mannosyl lipid. The mannosyl lipid co-chromatographs with hen oviduct dolichyl monophosphate β-mannose on three solvent systems. It is stable to mild alkaline hydrolysis, but strong alkaline treatment yields a compound that co-migrates with mannose 1-phosphate. The mannosyl lipid is labile to mild acid hydrolysis, yielding [14C]mannose. Formation of the compound is reversible by GDP, but not GMP, and is stimulated by exogenous dolichyl phosphate.
The kinetics of transfer of [14C]mannose from GDP-[14C]mannose to form dolichyl monophosphate mannose were studied by using preparations derived from rats fed on one of four diets: G (high glucose), L (high lard), F (fructose) or GC (high glucose, 0.9% cholesterol). The Km and Vmax. values for transfer from GDP-mannose were virtually indistinguishable in the four preparations.
In the absence of exogenous dolichyl phosphate, the largest amount of transfer of [14C]mannose into the mannosyl lipid was observed with preparations from fructose-fed animals. Preparations from glucose-fed animals showed about 60% as much transfer, whereas membranes from rats fed the other diets showed intermediate values between the fructose- and glucose-fed animals. The inclusion of cholesterol in the glucose diet elicited an increase in transfer of mannose.
Under conditions of saturating exogenous dolichyl phosphate, preparations from lard-fed animals have 1.5 times as much enzyme activity as do preparations from animals fed the other three diets.
Sustained activation of extracellular-signal-regulated kinase 1 (ERK1) is required for the continued expression of cyclin D1 in G1 phase
Authors: WEBER Jason D. , RABEN Daniel M. , PHILLIPS Polly J. , BALDASSARE Joseph J. 
Published: August 2015

In Chinese hamster embryo fibroblasts (IIC9 cells), platelet-derived growth factor (PDGF) stimulated mitogen-activated protein kinase/extracellular-signal-regulated kinase (MAP kinase/ERK) activity, but not that of c-jun N-terminal kinase (JNK), and induced G1 phase progression. ERK1 activation was biphasic and was sustained throughout the G1 phase of the cell cycle. PDGF induced cyclin D1 protein and mRNA levels in a time-dependent manner. Inhibition of PDGF-induced ERK1 activity by the addition of a selective inhibitor of MEK1 (MAP kinase kinase/ERK kinase 1) activation, PD98059, or transfection with a dominant-negative ERK1 (dnERK-) was correlated with growth arrest. In contrast, growth was unaffected by expression of dominant-negative JNK (dnJNK-). Interestingly, addition of PD98059 or dnERK-, but not dnJNK-, resulted in a dramatic decrease in cyclin D1 protein and mRNA levels, concomitant with a decrease in cyclin D1–cyclin-dependent kinase activity. To investigate the importance of sustained ERK1 activation, ERK1 activity was blocked by the addition of PD98059 throughout G1. Addition of PD98059 up to 4 h after PDGF treatment decreased ERK1 activity to the levels found in growth-arrested IIC9 cells. Loss of cyclin D1 mRNA and protein expression was observed within 1 h after inhibition of the second sustained phase of ERK1 activity. Disruption of sustained ERK1 activity also resulted in G1 growth arrest. These data provide evidence for a role for sustained ERK activity in controlling G1 progression through positive regulation of the continued expression of cyclin D1, a protein known to positively regulate G1 progression.
Interaction of nitric oxide with non-haem iron sites of Escherichia coli bacterioferritin: reduction of nitric oxide to nitrous oxide and oxidation of iron(II) to iron(III)
Authors: LE BRUN Nick E. , ANDREWS Simon C. , MOORE Geoffrey R. , THOMSON Andrew J. 
Published: August 2015

The bacterioferritin (BFR) of Escherichia coliconsists of 24 identical subunits, each containing a dinuclear metal-binding site consisting of two histidines and four carboxylic acid residues. Earlier studies showed that the characterization of iron binding to BFR could be aided by EPR analysis of iron–nitrosyl species resulting from the addition of NO to the protein [Le Brun, Cheesman, Andrews, Harrison, Guest, Moore and Thomson (1993) FEBS Lett. 323, 261–266]. We now report data from gas chromatographic head space analysis combined with EPR spectroscopy to show that NO is not an inert probe: iron(II)–BFR catalyses the reduction of NO to N2O, resulting in oxidation of iron(II) at the dinuclear centre and the subsequent detection of mononuclear iron(III). In the presence of excess reductant (sodium ascorbate), iron(II)–BFR also catalyses the reduction of NO to N2O, giving rise to three mononuclear iron–nitrosyl species which are detectable by EPR. One of these, a dinitrosyl–iron complex of S = ½, present at a maximum of one per subunit, is shown by EPR studies of site-directed variants of BFR not to be located at the dinuclear centre. This is consistent with a proposal that the diferric form of the centre is unstable and breaks down to form mononuclear iron species.
Interaction between Clostridium thermocellum endoglucanase CelD and polypeptides derived from the cellulosome-integrating protein CipA: stoichiometry and cellulolytic activity of the complexes
Authors: KATAEVA Irina , GUGLIELMI Gérard , BÉGUIN Pierre 
Published: August 2015

Four mini-scaffoldins were constructed from modules derived from the Clostridium thermocellum cellulosome-integrating protein CipA. Cip7 and Cip6 contained one and two cohesin modules respectively. Cip14 and Cip16, also containing one and two cohesin modules respectively, were flanked by a cellulose-binding domain. Endoglucanase CelD formed stable complexes with all mini-scaffoldins. Analytical ultracentrifugation of the complexes showed that 1 mol of CelD bound per mol of Cip14, and 2 mol of CelD bound per mol of Cip16. Under the conditions used for assaying cellulase activity, 96% of CelD alone bound to Avicel. Association with Cip14 or Cip16 increased the cellulose binding of CelD to 99%, while association with Cip7 or Cip6 decreased binding to 79 and 75% respectively. The hydrolytic activity of CelD against Avicel was increased 3-fold in complexes with Cip14 and Cip16, but remained substantially the same in complexes with Cip6 and Cip7. Addition of whole CipA also enhanced the efficiency of Avicel hydrolysis by CelD. However, even at an optimal ratio of the components, CelD–CipA complexes were somewhat less active than complexes of CelD with Cip14 or Cip16. These results suggest that the synergism observed between CelD and Cip14 or Cip16 is mostly due to the presence of the cellulose-binding domain, which promotes productive binding of the enzyme.
Common-type acylphosphatase: steady-state kinetics and leaving-group dependence
Authors: PAOLI Paolo , CIRRI Paolo , CAMICI Lucia , MANAO Giampaolo , CAPPUGI Gianni , MONETI Gloriano , PIERACCINI Giuseppe , CAMICI Guido , RAMPONI Giampietro 
Published: August 2015

A number of acyl phosphates differing in the structure of the acyl moiety (as well as in the leaving-group pKa of the acids produced in hydrolysis) have been synthesized. The Km and Vmax values for the bovine common-type acylphosphatase isoenzyme have been measured at 25 °C and pH 5.3. The values of kcat differ widely in relation to the different structures of the tested acyl phosphates: linear relationships between log kcat and the leaving group pKa, as well as between log kcat/Km and the leaving-group pKa, were observed. On the other hand, the Km values of the different substrates are very close to each other, suggesting that the phosphate moiety of the substrate is the main chemical group interacting with the enzyme active site in the formation of the enzyme–substrate Michaelis complex. The enzyme does not catalyse transphosphorylation between substrate and concentrated nucleophilic acceptors (glycerol and methanol); nor does it catalyse H218O–inorganic phosphate oxygen exchange. It seems that no phosphoenzyme intermediate is formed in the catalytic pathway. Furthermore, during the enzymic hydrolysis of benzoyl phosphate in the presence of 18O-labelled water, only inorganic phosphate (and not benzoate) incorporates 18O, suggesting that no acyl enzyme is formed transiently. All these findings, as well as the strong dependence of kcat upon the leaving group pKa, suggest that neither a nucleophilic enzyme group nor general acid catalysis are involved in the catalytic pathway. The enzyme is competitively inhibited by Pi, but it is not inhibited by the carboxylate ions produced during substrate hydrolysis, suggesting that the last step of the catalytic process is the release of Pi. The activation energy values for the catalysed and spontaneous hydrolysis of benzoyl phosphate have been determined.