bluuebunny/crossref_metadata_2025 huggingface dataset:
Geometrical effects of a subducted seamount on stopping megathrust ruptures
Authors: Yang Hongfeng , Liu Yajing , Lin Jian
Published: April 2013

We have numerically simulated dynamic ruptures along a “slip‐weakening” megathrust fault with a subducted seamount of realistic geometry, demonstrating that seamounts can act as a barrier to earthquake ruptures. Such barrier effect is calculated to be stronger for increased seamount normal stress relative to the ambient level, for larger seamount height‐to‐width ratio, and for shorter seamount‐to‐nucleation distance. As the seamount height increases from 0 to 40% of its basal width, the required increase in the effective normal stress on the seamount to stop ruptures drops by as much as ~20%. We further demonstrate that when a seamount is subducted adjacent to the earthquake nucleation zone, coseismic ruptures can be stopped even if the seamount has a lower effective normal stress than the ambient level. These results indicate that subducted seamounts may stop earthquake ruptures for a wide range of seamount normal stress conditions, including the case of the thrust fault being lubricated by seamount‐top fluid‐rich sediments, as suggested from observations in the Japan and Sunda Trenches.
Tidal dissipation in the early Eocene and implications for ocean mixing
Authors: Green J. A. M. , Huber M.
Published: April 2013

The tidally driven vertical diffusivity in the abyssal ocean during the early Eocene (55 Ma) is investigated using an established tidal model. A weak tide is predicted in the Eocene ocean, except in the Pacific. Consequently, the integrated global tidal dissipation rate is a mere 1.44TW, of which 40% dissipate in the Pacific. However, due to a stronger abyssal vertical stratification the predicted Eocene vertical diffusivities are consistently larger than at present. The results support the hypothesis that altered tidal dissipation may play a role in explaining the maintenance of past climate regimes, especially the anomalously warm temperatures in the southwest Pacific in the Eocene, and the low dissipation rates may be important for lunar evolution history.
Interannual variability of tropical tropopause layer clouds
Authors: Davis Sean M. , Liang Calvin K. , Rosenlof Karen H.
Published: April 2013

The quasi‐biennial oscillation (QBO), El Niño Southern Oscillation (ENSO), and upwelling in the tropical branch of the Brewer‐Dobson circulation (BDC) impact tropical tropopause layer (TTL, 14–19 km) temperature (T) and relative humidity (RH), and thus it is likely that they also affect the TTL cloud distribution. Satellite data reveal extreme interannual variability in the zonal‐mean TTL cloud occurrence frequency (CF) in the deep tropics (10°S–10°N). This zonal‐mean interannual variability is related to the QBO and BDC, with a relatively minor role for ENSO. However, over the whole tropics (30°S–30°N), the dominant mode of variability in the longitudinally resolved CF field is an ENSO‐related dipole pattern of positive and negative anomalies centered over the Pacific that mimics the RH/T fields. The ENSO effects largely cancel in the zonal mean, although El Niño is weakly associated with enhanced zonal‐mean cloudiness in the uppermost TTL over the short satellite record.
The 2011–2012 unrest at Santorini rift: Stress interaction between active faulting and volcanism
Authors: Feuillet Nathalie
Published: April 2013

At Santorini, active normal faulting controls the emission of volcanic products. Such geometry has implication on seismic activity around the plumbing system during unrest. Static Coulomb stress changes induced by the 2011–2012 inflation within a preexisting NW‐SE extensional regional stress field, compatible with fault geometry, increased by more than 0.5 MPa in an ellipsoid‐shaped zone beneath the Minoan caldera where almost all earthquakes (96%) have occurred since beginning of unrest. Magmatic processes perturb the regional stress in the caldera where strike‐slip rather than normal faulting along NE‐SW striking planes are expected. The inflation may have also promoted more distant moderate earthquakes on neighboring faults as the M > 5 January 2012, south of Christiania. Santorini belongs to a set of en echelon NE‐SW striking rifts (Milos, Nysiros) oblique to the Aegean arc that may have initiated in the Quaternary due to propagation of the North Anatolian fault into the Southern Aegean Sea.
Storage dynamics simulations in prairie wetland hydrology models: evaluation and parameterization
Authors: Shook Kevin , Pomeroy John W. , Spence Christopher , Boychuk Lyle
Published: April 2013

The contributing areas of streams in the Prairie regions of Canada and the northern U.S. are dominated by complexes of wetlands which store and release water. Prior research has suggested the existence of hysteresis between the total volume of water stored in prairie wetlands within a drainage basin and the basin's contributing area. To simulate the relationship between storage and contributing area in a way that accounts for hysteresis, two wetland hydrology models with vastly different levels of complexity were devised.

The fully distributed Wetland Digital Elevation Model (DEM) Ponding Model (WDPM) applies simple fluxes of runoff and evaporation to a DEM of a prairie wetland complex. The parameterized Pothole Cascade Model (PCM) applies simulated fluxes of water to collections of conceptual models of wetlands and is less demanding in computations and data. Prior research showed that both models produced hysteretic relationships between water storage and contributing area, but the PCM produced smaller estimates of contributing area than did the WDPM, likely due to its spatial simplification.

Using sequential remote sensing observations of wetland area after snowmelt, this study shows that the frequency distribution of the open water areas of prairie wetlands is similar to that produced by the WDPM when the wetlands are close to being completely filled. The remotely sensed observations show evidence of hysteresis in the open water area frequency distributions, as predicted by the fully distributed WDPM. To enable the parameterized PCM to produce the same type of hysteretic relationships as the WDPM, scaling relationships between the maximum area of a wetland and the area of upland draining into it were included. The parameterized PCM is suitable for application with prairie snow redistribution, snowmelt, infiltration, runoff and evapotranspiration routines as part of semi‐distributed hydrological modelling of prairie wetland basins such as that implemented in the Cold Regions Hydrological Model. Copyright © 2013 John Wiley & Sons, Ltd.
Comparison of approaches for snowpack estimation in New York City watersheds
Authors: Schneiderman Elliot M. , Matonse Adao H. , Zion Mark S. , Lounsbury David G. , Mukundan Rajith , Pradhanang Soni M. , Pierson Donald C.
Published: April 2013

Snow is a substantial component of historical annual precipitation in New York City (NYC) water supply watersheds in the Catskill Mountains, and the pattern of snow accumulation and snowmelt has important implications for the management of the reservoirs and watersheds that are part of the NYC water supply. NYC currently estimates reservoir basin‐scale snowpack throughout the snow season by extrapolation from biweekly snow survey data. These estimates are complemented by the NOAA Snow Data Assimilation System (SNODAS) product. Snowpack models are used in short‐term projections to support reservoir operations and long‐term simulations to evaluate the potential effects of climate change, land use change, and watershed management on the water supply. We tested three snowpack estimation approaches compared with snow survey data: the lumped‐parameter temperature index approach from the Generalized Watershed Loading Function (GWLF) watershed model, a spatially distributed temperature index (SDTI) model, and the spatially distributed NOAA SNODAS product. Of the spatially distributed approaches, SNODAS estimated the spatial variability of snow water equivalent (SWE) among snow survey sites within a basin better than the SDTI model. All three snowpack estimation approaches, including the lumped‐parameter GWLF model, performed well in estimating basin‐wide SWE for most of the basins studied. Copyright © 2013 John Wiley & Sons, Ltd.
Evidence for extreme variations in the permeability of laterite from a detailed analysis of well behaviour in Nigeria
Authors: Bonsor H. C. , MacDonald A. M. , Davies J.
Published: April 2013

Laterite soils are widespread in tropical Africa and have a large impact on the hydrology of the areas they cover. The permeability of laterite helps determine the partitioning of runoff and interflow and regulates groundwater recharge to underlying bedrock. Groundwater within laterite also forms a widespread source of drinking water, typically from unimproved hang‐dug‐wells. Despite its importance, there is little published information on laterite aquifer properties. In this study, data from a 6 m deep well in Nigeria have been analysed to characterise the hydraulic conductivity of the laterite from repeated pumping tests. Transmissivity measurements from 40 tests spread out across a hydrological year varied from 0.1 to 1000 m2/d. Further interpretation of the data demonstrate a strong non‐linear decrease in horizontal hydraulic conductivity with depth, characterised by an upper horizon of extreme permeability (400 m/d), and a much lower permeability profile beneath (<0.1 m/d). These data are substantiated with observations from other wells throughout the area. This non‐linear permeability structure has several implications: the upper laterite can facilitate rapid lateral throughflow in the wet season, enabling contaminants to be transported significant distances (up to 1 km); natural groundwater levels are restricted to a narrow range for much of the year; and, in the dry season, the lower permeability of the deeper laterite restricts the amount of water which can be abstracted from shallow wells, leading to well failure. The work highlights the need for a wider study to better understand laterite soils and the role they play in regional hydrology. © 2013 Natural Environment Research Council. Hydrological Processes published by John Wiley & Sons Ltd.
Antitumor T cell responses in bladder cancer are directed against a limited set of antigens and are modulated by regulatory T cells and routine treatment approaches
Authors: Horn Thomas , Grab Jessica , Schusdziarra Julia , Schmid Sebastian , Maurer Tobias , Nawroth Roman , Wolf Petra , Pritsch Maria , Gschwend Jürgen E. , Kübler Hubert R. , Beckhove Philipp
Published: April 2013

Regulatory T cells (Tregs) play a key role in cancer immune escape. We identified target antigens of spontaneous tumor‐specific T cell responses in urothelial carcinoma (UC) and evaluated their modulation by treatment and Treg. We determined Treg target antigens in UC. Fifty‐six UC and 13 control patients were prospectively enrolled. Blood was drawn before and after routine treatment. Changes in Treg frequency were measured by fluorescence cytometry and the T effector cell (Teff) response against a set of nine tumor‐associated antigens (TAAs) was monitored with an interferon‐gamma ELISpot. Antigen specificity of Treg was determined by their increased capacity to inhibit after TAA‐specific activation the proliferation of an autologous T cell population. The highest difference in the overall response rate for the total T cell population was observed for epidermal growth factor receptor (EGFR) (UC: 23% and controls: 0%). After depleting Treg, also new york esophageal (NYES)O1 (19 and 0%) and MUC20 (27 and 0%) were more frequently recognized in UC patients. In metastasized patients, the TAA‐directed T cell response was augmented by Treg depletion. Tumor resection seemed to diminish Treg suppression of TAA‐specific immunity, whereas chemotherapy had no effect. We demonstrated the existence of TAA‐specific Treg in UC, which share antigen specificities with Teff. The coexistence of TAA‐specific Treg and Teff was very rare. Treg frequencies in the peripheral blood were not changed by therapy. In summary, we identified potentially immunologically relevant TAA in UC. TAA‐specific T cell responses against these antigens are suppressed by Treg. We identified TAA‐specific Treg in UC patients, which do not cooccur with TAA‐specific Teff.
The effect of plasma‐nitrided titanium surfaces on osteoblastic cell adhesion, proliferation, and differentiation
Authors: Ferraz Emanuela P. , Sa Juliana C. , de Oliveira Paulo T. , Alves Clodomiro , Beloti Marcio M. , Rosa Adalberto L.
Published: April 2013

In this study, we evaluated the effect of new plasma‐nitrided Ti surfaces on the progression of osteoblast cultures, including cell adhesion, proliferation and differentiation. Ti surfaces were treated using two plasma‐nitriding protocols, hollow cathode for 3 h (HC 3 h) and 1 h (HC 1 h) and planar for 1 h. Untreated Ti surfaces were used as control. Cells derived from human alveolar and rat calvarial bones were cultured on Ti surfaces for periods of up to 14 days and the following parameters were evaluated: cell morphology, adhesion, spreading and proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and gene expression of key osteoblast markers. Plasma‐nitriding treatments resulted in Ti surfaces with distinct physicochemical characteristics. The cell adhesion and ALP activity were higher on plasma‐nitrided Ti surfaces compared with untreated one, whereas cell proliferation and extracellular matrix mineralization were not affected by the treatments. In addition, the plasma‐nitrided Ti surfaces increased the ALP, reduced the osteocalcin and did not affect the Runx2 gene expression. We have shown that HC 3 h and planar Ti surfaces slightly favored the osteoblast differentiation process, and then these surfaces should be considered for further investigation using preclinical models. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 991–998, 2014.
Decellularized liver scaffolds effectively support the proliferation and differentiation of mouse fetal hepatic progenitors
Authors: Wang Xiaojun , Cui Jing , Zhang Bing‐Qiang , Zhang Hongyu , Bi Yang , Kang Quan , Wang Ning , Bie Ping , Yang Zhanyu , Wang Huaizhi , Liu Xiangde , Haydon Rex C. , Luu Hue H. , Tang Ni , Dong Jiahong , He Tong‐Chuan
Published: April 2013

Decellularized whole organs represent ideal scaffolds for engineering new organs and/or cell transplantation. Here, we investigate whether decellularized liver scaffolds provide cell‐friendly biocompatible three‐dimensional (3‐D) environment to support the proliferation and differentiation of hepatic progenitor cells. Mouse liver tissues are efficiently decellularized through portal vein perfusion. Using the reversibly immortalized mouse fetal hepatic progenitor cells (iHPCs), we are able to effectively recellularize the decellularized liver scaffolds. The perfused iHPCs survive and proliferate in the 3‐D scaffolds in vitro for 2 weeks. When the recellularized scaffolds are implanted into the kidney capsule of athymic nude mice, cell survival and proliferation of the implanted scaffolds are readily detected by whole body imaging for 10 days. Furthermore, epidermal growth factor (EGF) is shown to significantly promote the proliferation and differentiation of the implanted iHPCs. Histologic and immunochemical analyzes indicate that iHPCs are able to proliferate and differentiate to mature hepatocytes upon EGF stimulation in the scaffolds. The recellularization of the biomaterial scaffolds is accompanied with vascularization. Taken together, these results indicate that decullarized liver scaffolds effectively support the proliferation and differentiation of iHPCs, suggesting that decellularized liver matrix may be used as ideal biocompatible scaffolds for hepatocyte transplantation. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1017–1025, 2014.
An artificial fusion protein between bone morphogenetic protein 2 and titanium‐binding peptide is functional in vivo
Authors: Yuasa Kazuaki , Kokubu Eitoyo , Kokubun Katsutoshi , Matsuzaka Kenichi , Shiba Kiyotaka , Kashiwagi Kenji , Inoue Takashi
Published: April 2013

The purpose of this study was to investigate osteogenesis using an artificial fusion protein (AFP) composed of modified bone morphogenetic protein 2 (BMP‐2) with a titanium (Ti)‐binding peptide (TBP) motif on a Ti surface in vivo. In the in vivostudy, 5‐μm thick Ti was coated with electron cyclotron resonance sputtering on a porous carbon scaffold which was then dipped in one of three different mixtures of collagen gel: (1) collagen gel only, (2) collagen gel with TBP, and (3) collagen gel with the AFP between BMP‐2 and the TBP motif (AFP‐TBP–BMP‐2). These scaffolds were then implanted into rat abdominal muscles and were studied histologically at various times and the expression of several bone‐related protein messenger RNAs (mRNAs) was also analyzed. The Ti‐coated scaffold of the collagen gel with AFP‐TBP–BMP‐2 produced cartilage in the muscle and the expression of alkaline phosphatase, bone sialoprotein, and runt‐related gene 2 mRNAs was significantly increased. These results suggest that the scaffold of the collagen gel with AFP‐TBP–BMP‐2 accelerates osteogenesis in vivo. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1180–1186, 2014.
Cartilage repair by local delivery of transforming growth factor‐β1 or bone morphogenetic protein‐2 from a novel, segmented polyurethane/polylactic‐co‐glycolic bilayered scaffold
Authors: Reyes Ricardo , Delgado Araceli , Solis Raul , Sanchez Esther , Hernandez Antonio , Roman Julio San , Evora Carmen
Published: April 2013

This study aimed to analyze the in vitro and in vivo release kinetics and evaluate the grades of repair induced by either the release of 50 ng of transforming growth factor‐β1 or 2.5 or 5 μg of bone morphogenetic protein‐2 (BMP‐2) from a bilayer scaffold of segmented polyurethane/polylactic‐co‐glycolic (SPU/PLGA) in osteochondral defects, in a rabbit model. The scaffold consisted of a porous, bone‐directed PLGA layer, overlaid with a cartilage‐directed layer of growth factor (GF)‐loaded PLGA microspheres, dispersed in a matrix of SPU. The PLGA porous layer was fabricated by gas foaming. Microspheres were prepared by a double emulsion method. SPU was synthesized by following the two‐step method. GF release kinetics were assessed using iodinated (125I) GFs. The in vivo release profiles of both GFs fitted to zero‐order kinetics, demonstrating a consistently good control of their release rates by SPU. Cartilage‐like tissue, characterized by histological analysis, scoring, and immunolabeling of chondrogenic differentiation markers, was observed only after 12 weeks, maintaining integrity up to at least 24 weeks, independently of the GF and the dose of BMP‐2. The biocompatibility and the resulting good quality, hyaline repair cartilage convert this system into a promising candidate for future applications in osteochondral lesions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1110–1120, 2014.
Blood Type B antigen modulates cell migration through regulating cdc42 expression and activity in HaCaT cells
Authors: Jung Ji‐Yong , Oh Jang‐Hee , Lee Dong Hun , Lee Serah , Chung Jin Ho
Published: April 2013

ABO blood group is determined by carbohydrate antigens, called ABH antigens. It has been known that the change of carbohydrate antigen expression, including ABH antigens, has correlation with the tumor metastasis and survival; however, the exact mechanism remains to be elucidated. ABH antigens are expressed not only in blood cells but also in several tissues. In epidermis, ABH antigen is expressed in the uppermost spinous and granular layer. We investigated the role of ABH antigens on the cell migration of HaCaT keratinocytes, which express B antigen. Knock‐down of B antigen expression by small interference RNA of FUT1 inhibited HaCaT cell migration. At that time, we found that lamellipodia and actin fiber were also reduced by knock‐down of B antigen expression. The transcription of cdc42, a kind of Rho GTPase which plays a key role in actin polymerization, was reduced by down‐regulated B antigen expression. Furthermore, the reduced B antigen expression also inhibited the interaction of cdc42 and N‐WASP. Collectively, our data provide a clue how ABH antigens regulate the cell migration mechanism. J. Cell. Physiol. 228: 2243–2251, 2013. © 2013 Wiley Periodicals, Inc.
MicroRNA‐302a sensitizes testicular embryonal carcinoma cells to cisplatin‐induced cell death
Authors: Liu Lin , Lian Jie , Zhang Huijuan , Tian Hui , Liang Meng , Yin Mianmian , Sun Fei
Published: April 2013

Cisplatin is a commonly used chemotherapeutic agent for the treatment of several human malignancies, such as testicular germ cell tumors (TGCT). The toxic effects persist and those that are present long after chemotherapy affect the overall quality of life of patients. MicroRNAs (miRNAs) play important roles in the responses of cancer cells to chemotherapy and have been shown to modulate cell sensitivity to chemotherapeutic drugs. However, the relationship between miRNA expression and cisplatin sensitivity of TGCT has not been fully explored. In this study, the effects of miR‐302a on cisplatin cytotoxicity in TGCT‐derived cell line NTERA‐2 (NT2) were evaluated. We found that expression levels of miR‐302a were increased in cisplatin‐treated NT2 cells. Up‐regulation of miR‐302a significantly increased the sensitivity of NT2 cells to cisplatin by enhancing cisplatin‐induced G2/M phase arrest and the subsequent progression to apoptosis. MiR‐302a also increased the killing effects of cisplatin by lowering the apoptotic threshold; the same result was also observed in another TGCT‐derived cell line, NCCIT. Furthermore, miR‐302a‐enhanced cisplatin sensitivity was partially mediated through the down‐regulation of p21 in NT2 cells. MiR‐302a induced apoptosis was further enhanced by silencing of p53 in NT2 cells. p53 levels were inversely associated with the expression of Oct4, Sox2, and Nanog in response to cisplatin. Thus, targeting miR‐302a may offer new therapeutic interventions in TGCT. J. Cell. Physiol. 228: 2294–2304, 2013. © 2013 Wiley Periodicals, Inc.
FUS/TLS assembles into stress granules and is a prosurvival factor during hyperosmolar stress
Authors: Sama Reddy Ranjith K. , Ward Catherine L. , Kaushansky Laura J. , Lemay Nathan , Ishigaki Shinsuke , Urano Fumihiko , Bosco Daryl A.
Published: April 2013

FUsed in Sarcoma/Translocated in LipoSarcoma (FUS/TLS or FUS) has been linked to several biological processes involving DNA and RNA processing, and has been associated with multiple diseases, including myxoid liposarcoma and amyotrophic lateral sclerosis (ALS). ALS‐associated mutations cause FUS to associate with stalled translational complexes called stress granules under conditions of stress. However, little is known regarding the normal role of endogenous (non‐disease linked) FUS in cellular stress response. Here, we demonstrate that endogenous FUS exerts a robust response to hyperosmolar stress induced by sorbitol. Hyperosmolar stress causes an immediate re‐distribution of nuclear FUS to the cytoplasm, where it incorporates into stress granules. The redistribution of FUS to the cytoplasm is modulated by methyltransferase activity, whereas the inhibition of methyltransferase activity does not affect the incorporation of FUS into stress granules. The response to hyperosmolar stress is specific, since endogenous FUS does not redistribute to the cytoplasm in response to sodium arsenite, hydrogen peroxide, thapsigargin, or heat shock, all of which induce stress granule assembly. Intriguingly, cells with reduced expression of FUS exhibit a loss of cell viability in response to sorbitol, indicating a prosurvival role for endogenous FUS in the cellular response to hyperosmolar stress. J. Cell. Physiol. 228: 2222–2231, 2013. © 2013 Wiley Periodicals, Inc.
Functional role of Runx3 in the regulation of aggrecan expression during cartilage development
Authors: Wigner Nathan A. , Soung Do Y. , Einhorn Thomas A. , Drissi Hicham , Gerstenfeld Louis C.
Published: April 2013

Runx2 and Runx3 are known to be expressed in the growth plate during endochondral bone formation. Here we addressed the functional role of Runx3 as distinct from Runx2 by using two models of postnatal bone repair: fracture healing that proceeds by an endochondral process and marrow ablation that proceeds by only an intramembranous process. Both Runx2 and Runx3 mRNAs were differentially up regulated during fracture healing. In contrast, only Runx2 showed increased expression after marrow ablation. During fracture healing, Runx3 was expressed earlier than Runx2, was concurrent with the period of chondrogenesis, and coincident with maximal aggrecan expression a protein associated with proliferating and permanent cartilage. Immunohistological analysis showed Runx3 protein was also expressed by chondrocytes in vivo. In contrast, Runx2 was expressed later during chondrocyte hypertrophy, and primary bone formation. The functional activities of Runx3 during chondrocyte differentiation were assessed by examining its regulatory actions on aggrecan gene expression. Aggrecan mRNA levels and aggrecan promoter activity were enhanced in response to the over‐expression of either Runx2 and Runx3 in ATDC5 chondrogenic cell line, while sh‐RNA knocked down of each Runx protein showed that only Runx3 knock down specifically suppressed aggrecan mRNA expression and promoter activity. ChIP assay demonstrated that Runx3 interactions were selective to sites within the aggrecan promoter and were only observed during early periods of chondrogenesis before hypertrophy. Our studies suggest that Runx3 positively regulates aggrecan expression and suggest that its function is more limited to cartilage development than to bone. In aggregate these data further suggest that the various members of the Runx transcription factors are involved in the coordination of chondrocyte development, maturation, and hypertrophy during endochondral bone formation. J. Cell. Physiol. 228: 2232–2242, 2013. © 2013 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.
Conditions at the magnetopause of Saturn and implications for the solar wind interaction
Authors: Desroche M. , Bagenal F. , Delamere P. A. , Erkaev N.
Published: April 2013

Using idealized models of the magnetosheath and magnetospheric magnetic fields, plasma densities, and plasma flow, we test for the steady state viability of processes mediating the interaction between the solar wind and the magnetosphere of Saturn. The magnetopause is modeled as an asymmetric paraboloid with a standoff distance of ∼25 RS. We test where on the magnetopause surface large‒scale reconnection may be affected by either a shear flow or diamagnetic drift due to a pressure gradient across the magnetopause boundary. We also test for the onset of the Kelvin‒Helmholtz instability. We find that, for the solar wind and magnetosphere states considered, reconnection is inhibited on the dawn flank due to the large shear flows in this region. Additionally, most of the dawn and dusk equatorial region of the magnetopause is Kelvin‒Helmholtz unstable, due to the presence of the dense magnetospheric plasma sheet and weak magnetic fields on either side of the magnetopause. This study is a follow‒up to a previously published study of the solar wind interaction with Jupiter's magnetosphere.
Intense current sheets in the magnetotail: Peculiarities of electron physics
Authors: Artemyev A. V. , Petrukovich A. A. , Frank A. G. , Nakamura R. , Zelenyi L. M.
Published: April 2013

In this paper we investigate intense (with current density larger than 15 nA/m2) thin (thickness is less than proton gyroradius) horizontal current sheets observed by Cluster in 2003 year in the Earth magnetotail. We compare observed profiles of the curlometer current density with particle currents and analytical estimates. We show that intense horizontal current sheets represent a particular class of current sheets where the almost all current density can be described by electron curvature currents. Intensification of these currents is provided by increase of the electron temperature anisotropy in of current sheets where parallel/antiparallel electron beams are found. The substantial part of the vertical pressure balance in such intense sheets can be supported by the local increase of the shear component of the magnetic field. We show that this is common property for intense current sheets observed in the magnetotail and in the laboratory experiments. The later measurements can help in understanding particular details, since spacecraft observations of such current sheets are relatively rare, especially due to their relation to localized active regions.
Storm time meridional wind perturbations in the equatorial upper thermosphere
Authors: Haaser R. A. , Davidson R. , Heelis R. A. , Earle G. D. , Venkatraman S. , Klenzing J.
Published: April 2013

We present observations from the Coupled Ion Neutral Dynamics Investigation (CINDI) of storm time meridional winds in the neutral atmosphere near the magnetic equator at 400 km altitude. Observations near the magnetic equator in the southern geographic hemisphere are dominated by energy inputs from the southern Polar Regions that produce south to north (equatorward) wind perturbations to accompany perturbations in the neutral density and temperature. In one exceptional case, when observations are made near midnight and the north magnetic pole rotates through the midnight sector, north to south (poleward) meridional wind perturbations are observed just south of the magnetic equator. Accompanying perturbations in the neutral density on the dayside and the nightside are consistent with observed increases in the ion temperature and inferred increases in the neutral temperature in accord with hydrostatic equilibrium.
Locating initial breakdown pulses using electric field change network
Authors: Karunarathne Sumedhe , Marshall Thomas C. , Stolzenburg Maribeth , Karunarathna Nadeeka , Vickers Lauren E. , Warner Tom A. , Orville Richard E.
Published: April 2013

Initial breakdown pulses (IBPs) observed in the fast electric field change (E‐change) at the beginning of intracloud (IC) and cloud‐to‐ground (CG) lightning flashes are located using a time‐of‐arrival technique called Position By Fast Antenna (PBFA) with data from a network of 10 E‐change sensors located at Kennedy Space Center. Location errors, estimated using a Monte Carlo method, are usually less than 100 m for horizontal coordinates and several hundreds of meters for altitude, depending on distance to the sensors and altitude of the source. Comparison of PBFA source locations to locations from a VHF lightning mapping system (Lightning Detection and Ranging II (LDAR2)) shows that PBFA locates most of the “classic” IBPs while LDAR2 locates only a few percent of them. As the flash develops during the IB stage, PBFA and LDAR2 obtain similar locations when they detect the same IBPs. The overall vertical motion indicated by the PBFA positions of IBPs was downward with time for CG flashes and upward with time for IC flashes. Location of the fast pulses due to return strokes of CG flashes is also determined using PBFA. Comparison to locations from the Cloud‐to‐Ground Lightning Surveillance System (CGLSS) shows that PBFA reliably locates ground strokes. These results are verified using ground truth data acquired with a high‐speed video camera. After cross calibration with the CGLSS data set, peak currents of return strokes are also determined.
Three years of lightning impulse charge moment change measurements in the United States
Authors: Cummer Steven A. , Lyons Walter A. , Stanley Mark A.
Published: April 2013

We report and analyze 3 years of lightning impulse charge moment change (iCMC) measurements obtained from an automated, real time lightning charge moment change network (CMCN). The CMCN combines U.S. National Lightning Detection Network (NLDN) lightning event geolocations with extremely low frequency (≲1 kHz) data from two stations to provide iCMC measurements across the entire United States. Almost 14 million lightning events were measured in the 3 year period. We present the statistical distributions of iCMC versus polarity and NLDN‐measured peak current, including corrections for the detection efficiency of the CMCN versus peak current. We find a broad distribution of iCMC for a given peak current, implying that these parameters are at best only weakly correlated. Curiously, the mean iCMC does not monotonically increase with peak current, and in fact, drops for positive CG strokes above +150 kA. For all positive strokes, there is a boundary near 20 C km that separates seemingly distinct populations of high and low iCMC strokes. We also explore the geographic distribution of high iCMC lightning strokes. High iCMC positive strokes occur predominantly in the northern midwest portion of the U.S., with a secondary peak over the gulf stream region just off the U.S. east coast. High iCMC negative strokes are also clustered in the midwest, although somewhat south of most of the high iCMC positive strokes. This is a region far from the locations of maximum occurrence of high peak current negative strokes. Based on assumed iCMC thresholds for sprite production, we estimate that approximately 35,000 positive polarity and 350 negative polarity sprites occur per year over the U.S. land and near‐coastal areas. Among other applications, this network is useful for the nowcasting of sprite‐producing storms and storm regions.
Historical Antarctic mean sea ice area, sea ice trends, and winds in CMIP5 simulations
Authors: Mahlstein Irina , Gent Peter R. , Solomon Susan
Published: April 2013

In contrast to Arctic sea ice, average Antarctic sea ice area is not retreating but has slowly increased since satellite measurements began in 1979. While most climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive simulate a decrease in Antarctic sea ice area over the recent past, whether these models can be dismissed as being wrong depends on more than just the sign of change compared to observations. We show that internal sea ice variability is large in the Antarctic region, and both the observed and modeled trends may represent natural variations along with external forcing. While several models show a negative trend, only a few of them actually show a trend that is significant compared to their internal variability on the time scales of available observational data. Furthermore, the ability of the models to simulate the mean state of sea ice is also important. The representations of Antarctic sea ice in CMIP5 models have not improved compared to CMIP3 and show an unrealistic spread in the mean state that may influence future sea ice behavior. Finally, Antarctic climate and sea ice area will be affected not only by ocean and air temperature changes but also by changes in the winds. The majority of the CMIP5 models simulate a shift that is too weak compared to observations. Thus, this study identifies several foci for consideration in evaluating and improving the modeling of climate and climate change in the Antarctic region.
Operculum ultrastructure in leech cocoons
Authors: Rossi Anthony M. , Saidel William M. , Marotta Roberto , Saglam Naim , Shain Daniel H.
Published: April 2013

Clitellate annelids (i.e., oligochaetes including leeches) secrete cocoons as part of their normal reproductive cycle. Typically, the cocoon sheath is passed over the head of the leech and sealed at both ends by opercula (i.e., glue‐like material secreted by the clitellum). Both the fibrous cocoon wall (CW) and opercula are chemically‐related biomaterials that share unusual physiochemical properties, including thermal and chemical resiliency. To explore the underlying morphology of the operculum, we examined cocoons from four leech species (i.e., Myzobdella lugubris, Theromyzon tessulatum, Erpobdella obscura, and Erpobdella punctata) by transmission (TEM) and scanning electron microscopy (SEM). Transmission electron micrographs of all opercula revealed a common, ultrastructural pattern comprising an electron‐dense mosaic of ordered polygons that surrounded interspersed cavities. The long axes of cavities were often oriented directionally, suggesting that operculum material is pliable prior to solidification and distorted as a consequence of cocoon deposition. Concomitantly, the operculum permeates jagged edges of the cocoon sheath sealing the cocoon, which provides a mechanically strong CW/operculum boundary. SEM of leech opercula revealed globular nanoparticles comparable to that observed in bioadhesives from disparate animal phyla (e.g., mussel, barnacle, sea star), suggesting a convergent mechanism of bioadhesion among animals. J. Morphol. 274:940–946, 2013. © 2013 Wiley Periodicals, Inc.
Long‐term changes in total and extreme precipitation over China and the United States and their links to oceanic–atmospheric features
Authors: Wang Fang , Yang Song , Higgins Wayne , Li Qiaoping , Zuo Zhiyan
Published: April 2013

We investigate the variations of total and extreme precipitations over China and the United States, focusing on long‐term changes. We also explain the features of precipitation by changes in sea surface temperature (SST) and atmospheric circulation. Features of total precipitation and the ratio of extreme to total precipitation are different between China and the United States, and differences occur in both annual and seasonal means. Both total precipitation and precipitation ratio show large seasonal and regional variations over China, but change modestly over the United States Annually, China total precipitation changes insignificantly and the ratio shows only a slight positive trend. However, the US annual total precipitation increases significantly, although the ratio decreases moderately. In China, the ratio exhibits positive trends in all seasons and total precipitation shows small positive trends except a negative trend in fall. The US total precipitation increases remarkably in all seasons except winter when a slight decrease occurs, and the ratio decreases in winter and summer but increases in spring and fall. The change in China precipitation ratio has a strong link to SSTs around the Indian Ocean and the South and East China Seas, and the change in US total precipitation is associated with changes in the Indian Ocean and eastern Pacific SSTs. These relationships become weaker when the trend of total precipitation or precipitation ratio is removed, indicating an impact of SST on the long‐term change in precipitation. The trends of US total precipitation and China precipitation ratio are also linked to the long‐term changes inatmospheric circulation including the trade wind, the North Pacific anticyclone, and the circulation patternsover Asia. In most cases, the total and extreme precipitations are associated with similar SST and atmospheric patterns, except in China where the annual extreme precipitation is associated with SST and circulation features as is the precipitation ratio.
Shifting of frozen ground boundary in response to temperature variations at northern China and Mongolia, 2000–2007
Authors: Han Lijian , Tsunekawa Atsushi , Tsubo Mitsuru
Published: April 2013

Little is known about the shifts of frozen ground boundary in response to temperature variations in the East Asia. We therefore examined the relationship between changes of frozen ground boundary and temperature at northern China and Mongolia. Significant relationships were found between the boundaries' shifting and monthly average air temperature in northeast of China and in the northeast of Mongolia, where the higher temperature resulted in the more northward boundary of frozen ground. However, no significant relationship was found in northwest of Mongolia, in west of China, and in the west of Tibetan Plateau. These results indicate that the temperature is not the major factor in driving the boundary of seasonally frozen ground shifting at typical mid‐latitude areas in Asia. This research demonstrates seasonally frozen ground dynamic response to climatic change at some mid‐latitude areas where seasonally frozen ground boundary shifting would be utilized as an additional factor for tracking climatic change. Copyright © 2013 Royal Meteorological Society
Influence of the buffer layer properties on the intensity of Raman scattering of graphene
Authors: Dyakov S. A. , Perova T. S. , Miao C. Q. , Xie Y.‐H. , Cherevkov S. A. , Baranov A. V.
Published: April 2013

Using a model of oscillating dipoles, we simulate the intensity of the G‐band in the Raman signal from structures consisting of graphene, separated by an arbitrary buffer layer from a substrate. It is found that a structure with an optimized buffer layer refractive index and thickness exhibits a Raman signal which is nearly 50 times more intense than that from the same structure with a non‐optimized buffer layer. The theoretical simulations are verified by Raman measurements on structures consisting of a layer of graphene on SiO2 and Al2O3 buffer layers. The optical contrast of the single graphene layer is calculated for an arbitrary buffer layer. It was found that both the Raman intensity and optical contrast can be maximized by varying the buffer layer thickness. Copyright © 2013 John Wiley & Sons, Ltd.
The thermal stability of graphene in air investigated by Raman spectroscopy
Authors: Nan Hai Yan , Ni Zhen Hua , Wang Jun , Zafar Zainab , Shi Zhi Xiang , Wang Ying Ying
Published: April 2013

The thermal stability in air of graphene synthesized by either chemical vapor deposition or mechanical cleavage is studied. It is found that single layer graphene prepared by both methods starts to show defects at ~500 °C, indicated by the appearance of a disorder‐induced Raman D peak. The defects are initially sp3 type and become vacancy like at higher temperature. On the other hand, bilayer graphene shows better thermal stability, and the D peak appears at ~600 °C. These results are quite different from those annealing in vacuum and controlled atmosphere. Raman images show that the defects in chemical vapor deposition graphene are not homogeneous, whereas those in mechanical cleavage graphene are uniformly distributed across the whole sample. The factors that affect the thermal stability of graphene are discussed. Our results could be important for guiding the future electronics process and chemical decoration of graphene. Copyright © 2013 John Wiley & Sons, Ltd.
Optimization of programmed‐temperature vaporization injection preparative capillary GC for compound specific radiocarbon analysis
Authors: Zhang Xinyu , Zhao Liang , Wang Yexin , Xu Yunping , Zhou Liping
Published: April 2013

Preparative capillary GC (PCGC) is a powerful tool for the separation and purification of compounds from any complex matrix, which can be used for compound‐specific radiocarbon analysis. However, the effect of PCGC parameters on the trapping efficiency is not well understood. Here, we present a comprehensive study on the optimization of parameters based on 11 reference compounds with different physicochemical properties. Under the optimum conditions, the trapping efficiencies of these 11 compounds (including high‐boiling‐point n‐hentriacontane and methyl lignocerate) are about 80% (60–89%). The isolation of target compounds from standard solutions, plant and soil samples demonstrates that our optimized method is applicable for different classes of compounds including n‐alkanes, fatty acid esters, long‐chain fatty alcohol esters, polycyclic aromatic hydrocarbons (PAHs) and steranes. By injecting 25 μL in large volume injection mode, over 100 μg, high purity (>90%) target compounds are harvested within 24 h. The recovery ranges of two real samples are about 70% (59.9–83.8%) and about 83% (77.2–88.5%), respectively. Compared to previous studies, our study makes significant improvement in the recovery of PCGC, which is important for its wide application in biogeochemistry, environmental sciences, and archaeology.
A novel sorbent for chromatographic separations: A silica matrix modified with non‐covalently bonded tetrakis(β‐cyclodextrin)–porphyrin conjugates
Authors: Kejík Zdeněk , Kaplánek Robert , Rak Jakub , Plátová Marie , Vosmanská Magda , Martásek Pavel , Král Vladimír
Published: April 2013

We prepared new phases for LC that consisted of silica modified with non‐covalently bonded tetrakis(β‐cyclodextrin)–porphyrin (where cyclodextrin is CD) conjugates. The effects of the porphyrin core, type of spacer and β‐CD moieties on the behaviours of the modified phases for the separation of aromatic compounds (benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, o‐terphenyl, triphenylene, phenol and caffeine) and fluorinated aromatic compounds (pentafluorobenzonitrile, pentafluoronitrobenzene and hexafluorobenzene) were studied using the Tanaka test. The results indicate that the non‐covalent substitution of silica with CD‐based macromolecules that have a porphyrin core can be a very effective method for preparing novel sorbents with specific chromatographic properties for applications in LC.
Separation of chlorogenic acid and concentration of trace caffeic acid from natural products by pH‐zone‐refining countercurrent chromatography
Authors: Lu Yuanyuan , Dong Genlai , Gu Yanxiang , Ito Yoichiro , Wei Yun
Published: April 2013

Chlorogenic acid and caffeic acid were selected as test samples for separation by the pH‐zone‐refining countercurrent chromatography (CCC). The separation of these test samples was performed with a two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/water at a volume ratio of 4:1:5 v/v/v where trifluoroacetic acid (TFA; 8 mM) was added to the organic stationary phase as a retainer and NH4OH (10 mM) to the aqueous mobile phase as an eluter. Chlorogenic acid was successfully separated from Flaveria bidentis (L.) Kuntze (F. bidentis) and Lonicerae Flos by pH‐zone‐refining CCC, a slightly polar two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/n‐butanol/water at a volume ratio of 4:1:1:5 v/v/v/v was selected where TFA (3 mM) was added to the organic stationary phase as a retainer and NH4OH (3 mM) to the aqueous mobile phase as an eluter. A 16.2 mg amount of chlorogenic acid with the purity of 92% from 1.4 g of F. bidentis, and 134 mg of chlorogenic acid at the purity of 99% from 1.3 g of crude extract of Lonicerae Flos have been obtained. These results suggest that pH‐zone‐refining CCC is suitable for the isolation of the chlorogenic acid from the crude extracts of F. bidentis and Lonicerae Flos.
The Ah receptor regulates growth factor expression in head and neck squamous cell carcinoma cell lines
Authors: John Kaarthik , Lahoti Tejas S. , Wagner Kelly , Hughes Jarod M. , Perdew Gary H.
Published: April 2013

Previous studies in head and neck squamous cell carcinoma (HNSCC) cell lines have revealed that the Ah receptor (AHR) plays a significant role in mediating the “aggressive” phenotype of these cells, which includes enhanced inflammatory signaling (e.g., IL6) and migratory potential. Here we sought to identify putative novel targets of the AHR associated with enhanced tumor invasiveness. Global gene expression analysis identified a number of genes that are repressed upon treatment of OSC‐19 or HN30 cells with an AHR antagonist. Three growth factors were targets of AHR activity; amphiregulin (AREG), epiregulin (EREG), and platelet‐derived growth factor A (PDGFA) were repressed by an AHR antagonist and further examined. Quantitative PCR analysis, ELISA, and siRNA‐mediated knock down of AHR revealed an attenuation of basal and/or induced levels of expression of these growth factors in two HNSCC lines, following AHR antagonism. In silico analysis revealed that these growth factors possess dioxin‐like response elements. Two other AHR ligands, 6‐formylindolo[3,2‐b]carbazole and benzo(a)pyrene (BP) also elicited similar responses. In conclusion, this study identified AREG, EREG, and PDGFA as growth factor targets of AHR activity associated with metastatic phenotype of HNSCC cells, suggesting that attenuation of AHR activity may be a therapeutic strategy. © 2013 Wiley Periodicals, Inc.