bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow-induced degradation of drag-reducing polymer solutions within a high-Reynolds-number turbulent boundary layer
Authors: ELBING BRIAN R. , SOLOMON MICHAEL J. , PERLIN MARC , DOWLING DAVID R. , CECCIO STEVEN L.
Published: February 2011

Polymer drag reduction, diffusion and degradation in a high-Reynolds-number turbulent boundary layer (TBL) flow were investigated. The TBL developed on a flat plate at free-stream speeds up to 20ms−1. Measurements were acquired up to 10.7m downstream of the leading edge, yielding downstream-distance-based Reynolds numbers up to 220 million. The test model surface was hydraulically smooth or fully rough. Flow diagnostics included local skin friction, near-wall polymer concentration, boundary layer sampling and rheological analysis of polymer solution samples. Skin-friction data revealed that the presence of surface roughness can produce a local increase in drag reduction near the injection location (compared with the flow over a smooth surface) because of enhanced mixing. However, the roughness ultimately led to a significant decrease in drag reduction with increasing speed and downstream distance. At the highest speed tested (20ms−1) no drag reduction was discernible at the first measurement location (0.56m downstream of injection), even at the highest polymer injection flux (10 times the flux of fluid in the near-wall region). Increased polymer degradation rates and polymer mixing were shown to be the contributing factors to the loss of drag reduction. Rheological analysis of liquid drawn from the TBL revealed that flow-induced polymer degradation by chain scission was often substantial. The inferred polymer molecular weight was successfully scaled with the local wall shear rate and residence time in the TBL. This scaling revealed an exponential decay that asymptotes to a finite (steady-state) molecular weight. The importance of the residence time to the scaling indicates that while individual polymer chains are stretched and ruptured on a relatively short time scale (~10−3s), because of the low percentage of individual chains stretched at any instant in time, a relatively long time period (~0.1s) is required to observe changes in the mean molecular weight. This scaling also indicates that most previous TBL studies would have observed minimal influence from degradation due to insufficient residence times.
Aspects of working memory in L2 learning
Authors: Juffs Alan , Harrington Michael
Published: February 2011

This article reviews research on working memory (WM) and its use in second language (L2) acquisition research. Recent developments in the model and issues surrounding the operationalization of the construct itself are presented, followed by a discussion of various methods of measuring WM. These methods include word and digit span tasks, reading, listening and speaking span tasks. We next outline the role proposed for WM in explaining individual differences in L2 learning processes and outcomes, including sentence processing, reading, speaking, lexical development and general proficiency. Key findings are that WM is not a unitary construct and that its role varies depending on the age of the L2 learners, the task and the linguistic domain. Some tests of WM may in fact be tests of differences in ability to attend to aspects of the L2. Future research will focus on matching tests of WM more closely with linguistic tasks and using more standardized, replicable measures of WM in new areas including writing in non-alphabetic scripts, instructional interventions and cognitive neuropsychology.
Common property theory and resource governance institutions: strengthening explanations of multiple outcomes
Authors: AGRAWAL ARUN , BENSON CATHERINE SHANNON
Published: February 2011

Different strategies to govern resource commons generate outcomes that can be assessed along different dimensions, in terms of the ecological or social sustainability of the resource system, contributions to the livelihoods of those who rely on these resources, or equity in the allocation of benefits. This paper reviews the existing literature concerning three major renewable resource commons, namely pasture lands, fisheries and irrigation water. Most existing work on these commons has been inattentive to the multiple outcomes that management of all renewable resources generates. Studies of commons can provide better information about livelihoods, sustainability and equity dimensions of natural resource governance outcomes than previously. Attending to the distinctive determinants and drivers of these outcomes and the nature of trade-offs and synergies among them has the potential to advance common property theory substantially. Possible relationships among livelihoods, sustainability and equity are identified, and the major explanations of outcomes advanced by scholars of fisheries, pastoral and irrigation commons reviewed. An interdisciplinary approach is needed to improve existing efforts to determine the outcomes that resource commons generate.
Influence of nutrition on feline calcium oxalate urolithiasis with emphasis on endogenous oxalate synthesis
Authors: Dijcker J. C. , Plantinga E. A. , van Baal J. , Hendriks W. H.
Published: February 2011

The prevalence of calcium oxalate (CaOx) uroliths detected in cats with lower urinary tract disease has shown a sharp increase over the last decades with a concomitant reciprocal decrease in the occurrence of struvite (magnesium ammonium phosphate) uroliths. CaOx stone-preventative diets are available nowadays, but seem to be marginally effective, as CaOx urolith recurrence occurs in patients fed these diets. In order to improve the preventative measures against CaOx urolithiasis, it is important to understand its aetiopathogenesis. The main research focus in CaOx formation in cats has been on the role of Ca, whereas little research effort has been directed towards the role and origin of urinary oxalates. As in man, the exogenous origin of urinary oxalates in cats is thought to be of minor importance, although the precise contribution of dietary oxalates remains unclear. The generally accepted dietary risk factors for CaOx urolithiasis in cats are discussed and a model for the biosynthetic pathways of oxalate in feline liver is provided. Alanine:glyoxylate aminotransferase 1 (AGT1) in endogenous oxalate metabolism is a liver-specific enzyme targeted in the mitochondria in cats, and allows for efficient conversion of glyoxylate to glycine when fed a carnivorous diet. The low peroxisomal activity of AGT1 in cat liver is compatible with the view that felids utilised a low-carbohydrate diet throughout evolution. Future research should focus on understandingde novobiosynthesis of oxalate in cats and their adaptation(s) in oxalate metabolism, and on dietary oxalate intake and absorption by cats.
Expression of ZO-1 and occludin at mRNA and protein level during preimplantation development of the pig parthenogenetic diploids
Authors: Xu Shangdan , Lee Jibak , Miyake Masashi
Published: February 2011

Expression of mRNAs and proteins of ZO-1 and occludin was analyzed in pig oocytes and parthenogenetic diploid embryos during preimplantation development using real-time RT-PCR, western blotting and immunocytochemistry. All germinal vesicle (GV) and metaphase (M)II oocytes and preimplantation embryos expressed mRNAs and proteins of ZO-1 and occludin. mRNA levels of both ZO-1 and occludin decreased significantly from GV to MII, but increased at the 2-cell stage followed by temporal decrease during the early and late 4-cell stages. Then, both mRNAs increased after compaction. Relative concentration ofzo1α−was highest in 2-cell embryos, whilezo1α+was expressed from the morula stage.Occludinexpression greatly increased after the morula stage and was highest in expanded blastocysts. Western blotting analysis showed constant expression of ZO-1α−throughout preimplantation development and limited translation of ZO-1α+from the blastocysts, and species-specific expression pattern of occludin. Immunocytochemistry analysis revealed homogeneous distribution of ZO-1 and occludin in the cytoplasm with moderately strong fluorescence in the vicinity of the contact region between blastomeres, around the nuclei in the 2-cell to late 4-cell embryos, and clear network localization along the cell-boundary region in embryos after the morula stage. Present results show that major TJ proteins, ZO-1 and occludin are expressed in oocytes and preimplantation embryos, and that ZO-1α+is transcribed by zygotic gene activation and translated from early blastocysts with prominent increase of occludin at the blastocyst stage.
Patients with Posttraumatic Stress Disorder Show Decreased Cognitive Control: Evidence from Dichotic Listening
Authors: Johnsen Grethe E. , Kanagaratnam Pushpa , Asbjørnsen Arve E.
Published: February 2011

The influence of posttraumatic stress disorder (PTSD) on cognitive control and auditory attention modulation was examined with the use of a dichotic-listening (DL) task. The participants were 45 war-exposed refugees. The PTSD group comprised 22 participants meeting the DSM-IV criteria for PTSD, and the Control group comprised 23 war-exposed participants without PTSD. Both groups were tested with a consonant–vowel syllables DL task under three different attentional instructions. The two groups did not differ in the non-forced and forced-right conditions and showed, as expected, right-ear advantages. The Control group showed, as expected, a left-ear advantage in the forced-left (FL) condition. However, the PTSD group continued to show a right-ear advantage - and only minor modulation of the performance during the FL condition. This finding suggests that PTSD is associated with a reduced capacity for top-down attentional control of a bottom-up or stimulus-driven effect. The result shows that participants with PTSD have impaired cognitive control functions when tested on information processing of neutral stimuli. (JINS, 2011, 17, 344–353)
Activation of the Occipital Cortex and Deactivation of the Default Mode Network During Working Memory in the Early Blind
Authors: Park Hae-Jeong , Chun Ji-Won , Park Bumhee , Park Haeil , Kim Joong Il , Lee Jong Doo , Kim Jae-Jin
Published: February 2011

Although blind people heavily depend on working memory to manage daily life without visual information, it is not clear yet whether their working memory processing involves functional reorganization of the memory-related cortical network. To explore functional reorganization of the cortical network that supports various types of working memory processes in the early blind, we investigated activation differences between 2-back tasks and 0-back tasks using fMRI in 10 congenitally blind subjects and 10 sighted subjects. We used three types of stimulus sequences: words for a verbal task, pitches for a non-verbal task, and sound locations for a spatial task. When compared to the sighted, the blind showed additional activations in the occipital lobe for all types of stimulus sequences for working memory and more significant deactivation in the posterior cingulate cortex of the default mode network. The blind had increased effective connectivity from the default mode network to the left parieto-frontal network and from the occipital cortex to the right parieto-frontal network during the 2-back tasks than the 0-back tasks. These findings suggest not only cortical plasticity of the occipital cortex but also reorganization of the cortical network for the executive control of working memory. (JINS, 2011, 17, 407–422)
Grammar without speech production: The case of Labrador Inuttitut heritage receptive bilinguals
Authors: SHERKINA-LIEBER MARINA , PEREZ-LEROUX ANA T. , JOHNS ALANA
Published: February 2011

We examine morphosyntactic knowledge of Labrador Inuttitut by Inuit receptive bilinguals (RBs) – heritage speakers who are capable of comprehension, but produce little or no speech. A grammaticality judgment study suggests that RBs possess sensitivity to morphosyntactic violations, though to a lesser degree than fluent bilinguals. Low-proficiency RBs are sensitive only to the most basic grammatical properties. Case omission is most difficult to detect, but morphemes bearing incorrect features (case oversuppliance, number agreement mismatch) or ordered incorrectly (tense and agreement, tense and negation) are easier, and performance on incorrect ordering of morphemes is near target with the core agreement morpheme for all RBs. While receptive bilinguals show patterns of grammatical deficits, they also demonstrate clear knowledge of the basic properties of word structure in Inuttitut. This has implications both for the psycholinguistics of bilingualism and for language revitalization efforts.
Reduced food access due to a lack of money, inability to lift and lack of access to a car for food shopping: a multilevel study in Melbourne, Victoria
Authors: Burns Cate , Bentley Rebecca , Thornton Lukar , Kavanagh Anne
Published: February 2011

Objective

To describe associations between demographic and individual and area-level socio-economic variables and restricted household food access due to lack of money, inability to lift groceries and lack of access to a car to do food shopping.

Design

Multilevel study of three measures of restricted food access, i.e. running out of money to buy food, inability to lift groceries and lack of access to a car for food shopping. Multilevel logistic regression was conducted to examine the risk of each of these outcomes according to demographic and socio-economic variables.

Setting

Random selection of households from fifty small areas in Melbourne, Australia, in 2003.

Subjects

The main food shoppers in each household (n 2564).

Results

A lack of money was significantly more likely among the young and in households with single adults. Difficultly lifting was more likely among the elderly and those born overseas. The youngest and highest age groups both reported reduced car access, as did those born overseas and single-adult households. All three factors were most likely among those with a lower individual or household socio-economic position. Increased levels of area disadvantage were independently associated with difficultly lifting and reduced car access.

Conclusions

In Melbourne, households with lower individual socio-economic position and area disadvantage have restricted access to food because of a lack of money and/or having physical limitations due difficulty lifting or lack of access to a car for food shopping. Further research is required to explore the relationship between physical restrictions and food access.
Prevalence of overweight and obesity among migrants in Switzerland: association with country of origin
Authors: Marques-Vidal Pedro , Vollenweider Peter , Waeber Gérard , Paccaud Fred
Published: February 2011

Objective

Migrants tend to present higher overweight and obesity levels, but whether this relationship applies to all nationalities has seldom been studied. The present study aimed to assess the prevalence of overweight and obesity according to nationality in adults.

Design

Cross-sectional population-based samples.

Setting

Five-year nationwide interview surveys (Swiss Health Surveys – SHS) from 1992 to 2007 (n 63 766) and a local examination survey (CoLaus Study in Lausanne 2004–2006, n 6743).

Subjects

Participants were separated into Swiss, French, German, Italian, Portuguese, Spanish nationals, those from the former Republic of Yugoslavia and from other European and other countries.

Results

Compared with Swiss nationals, German and French nationals presented a lower prevalence of overweight and obesity, whereas nationals from Italy, Spain, Portugal and the former Republic of Yugoslavia presented higher levels. Adjusting the SHS data for age, gender, education, smoking, leisure-time physical activity and survey year, a lower risk for overweight and obesity was found for German (OR = 0·80, 95 % CI 0·70, 0·92) and French (OR = 0·74, 95 % CI 0·61, 0·89) nationals, whereas higher risks were found for participants from Italy (OR = 1·45, 95 % CI 1·33, 1·58), Spain (OR = 1·36, 95 % CI 1·15, 1·61), Portugal (OR = 1·25, 95 % CI 1·06, 1·47) and the former Republic of Yugoslavia (OR = 1·98, 95 % CI 1·69, 2·32). Similar findings were observed in the CoLaus Study for Italian (OR = 1·63, 95 % CI 1·29, 2·06), Spanish (OR = 1·54, 95 % CI 1·17, 2·04) and Portuguese (OR = 1·49, 95 % CI 1·16, 1·91) participants and for those from the former Republic of Yugoslavia (OR = 5·34, 95 % CI 3·00, 9·50).

Conclusions

Overweight and obesity are unevenly distributed among migrants in Switzerland. Migrants from Southern Europe and from the former Republic of Yugoslavia present higher prevalence rates. This suggests that preventive messages should be tailored to these specific populations.
Intake of whole grains in Scandinavia is associated with healthy lifestyle, socio-economic and dietary factors
Authors: Kyrø Cecilie , Skeie Guri , Dragsted Lars O , Christensen Jane , Overvad Kim , Hallmans Göran , Johansson Ingegerd , Lund Eiliv , Slimani Nadia , Johnsen Nina F , Halkjær Jytte , Tjønneland Anne , Olsen Anja
Published: February 2011

Objective

To identify the dietary, lifestyle and socio-economic factors associated with the intake of whole grains (WG) in Norway, Sweden and Denmark.

Design

A cross-sectional study.

Setting

Subsample of the Scandinavian cohort ‘HELGA’ consisting of three prospective cohorts: The Norwegian Women and Cancer Study; The Northern Sweden Health and Disease Study; and the Danish Diet, Cancer and Health Study.

Subjects

A total of 8702 men and women aged 30–65 years. Dietary data are from one 24 h dietary recall and data on socio-economic status and lifestyle factors including anthropometric values are from the baseline collection of data.

Results

Vegetables, fruits, dairy products, fish and shellfish, coffee, tea and margarine were directly associated with the intake of WG, whereas red meat, white bread, alcohol and cakes and biscuits were inversely associated. Smoking and BMI were consistently inversely associated with the intake of WG. Furthermore, length of education was directly associated with the intake of WG among women.

Conclusions

The intake of WG was found to be directly associated with healthy diet, lifestyle and socio-economic factors and inversely associated with less healthy factors, suggesting that these factors are important for consideration as potential confounders when studying WG intake and disease associations.
Abstract answer set solvers with backjumping and learning
Authors: LIERLER YULIYA
Published: February 2011

Nieuwenhuis et al. (2006. Solving SAT and SAT modulo theories: From an abstract Davis-Putnam-Logemann-Loveland procedure to DPLL(T). Journal of the ACM 53(6), 937977 showed how to describe enhancements of the Davis–Putnam–Logemann–Loveland algorithm using transition systems, instead of pseudocode. We design a similar framework for several algorithms that generate answer sets for logic programs: smodels, smodelscc, asp-sat with Learning (cmodels), and a newly designed and implemented algorithm sup. This approach to describe answer set solvers makes it easier to prove their correctness, to compare them, and to design new systems.
Channel response in a semiarid stream to removal of tamarisk and Russian olive
Authors: Jaeger Kristin L. , Wohl Ellen
Published: February 2011

We report observed short‐term (3 years) channel adjustment in an incised, semiarid stream to the removal of invasive plants, tamarisk (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) by (1) removing the above‐ground portion of the plant (cut‐stump method) and (2) removing the entire plant (whole‐plant method). The stream flows through Canyon de Chelly National Monument in Arizona, USA., draining an ∼1500 km2 catchment. Average channel width is 13 m; average thalweg depth is 2–3 m, although channel banks exceed 8 m locally. Channels adjusted primarily through widening, with significantly larger changes occurring in whole‐plant removal reaches; however, neither plant removal method elicited large‐scale bank destabilization, and the channels remained entrenched. Particular site conditions limiting large‐scale destabilization include the absence of sufficient streamflow magnitudes, the presence of clay layers at the bank toe, the remaining presence of native vegetation, and the entrenched morphology. Our findings serve as a cautionary note regarding the temporal and spatial variability in channel response to invasive plant removal and underscore the importance of considering site‐specific conditions in future restoration projects that include invasive plant removal.
Analytical confidence intervals for index flow flow duration curves
Authors: Serinaldi F.
Published: February 2011

This study illustrates how analytical period‐of‐record flow duration curves (FDCs) and annual FDCs (AFDCs) of daily streamflow series developed in an index flow framework can be complemented by theoretical confidence intervals (CIs) deduced from the theory of nonparametric CIs for quantiles and fractional order statistics. By focusing on AFDCs, the proposed approach yields results very close to CIs for order statistics which are commonly used to construct AFDCs and CIs for AFDCs. When the method is applied to index flow FDCs, the comparison with Monte Carlo techniques allows the elucidation of some properties of FDCs which have not been previously explored in depth. The approach helps to overcome the problem of lack of CIs for index flow FDCs by introducing approximate analytical CIs based on an effective sample size. Thus, the underlying idea is emphasized that CIs of index flow FDCs and AFDCs can be coherently obtained by reasoning in terms of distribution of quantiles rather than distribution of order statistics. Moreover, a few results taken from nonparametric statistics allow the introduction of semiparametric index flow FDCs and AFDCs which are potentially useful for parsimonious regionalization procedures.
On the use of satellite‐based estimates of rainfall temporal distribution to simulate the potential for malaria transmission in rural Africa
Authors: Yamana Teresa K. , Eltahir Elfatih A. B.
Published: February 2011

This paper describes the use of satellite‐based estimates of rainfall to force the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS), a hydrology‐based mechanistic model of malaria transmission. We first examined the temporal resolution of rainfall input required by HYDREMATS. Simulations conducted over Banizoumbou village in Niger showed that for reasonably accurate simulation of mosquito populations, the model requires rainfall data with at least 1 h resolution. We then investigated whether HYDREMATS could be effectively forced by satellite‐based estimates of rainfall instead of ground‐based observations. The Climate Prediction Center morphing technique (CMORPH) precipitation estimates distributed by the National Oceanic and Atmospheric Administration are available at a 30 min temporal resolution and 8 km spatial resolution. We compared mosquito populations simulated by HYDREMATS when the model is forced by adjusted CMORPH estimates and by ground observations. The results demonstrate that adjusted rainfall estimates from satellites can be used with a mechanistic model to accurately simulate the dynamics of mosquito populations.
Soil water dynamics around a tree on a hillslope with or without rainwater supplied by stemflow
Authors: Liang Wei‐Li , Kosugi Ken'ichirou , Mizuyama Takahisa
Published: February 2011

A tree can partition rainfall into throughfall and stemflow (SF), causing water to be funneled around the tree base, and can preferentially divert rainwater in soil layers, causing water to be funneled around tree roots. To determine the effects of each on soil water dynamics, we compared soil water dynamics around a tree on a hillslope on the basis of 2 years of field observations before (SF period) and after (non‐SF period) intercepting the stemflow of the tree. Additionally, two sprinkling experiments were conducted using different dye tracers to separately indentify infiltration pathways derived from throughfall and stemflow. The observation results in the SF period showed irregular variations in soil water content, high soil water storage, and significant saturated zone development in the downslope region from the tree, which were attributed to stemflow concentrated on the downslope side of the tree. Although dramatic variations in soil water dynamics disappeared in the non‐SF period, asymmetrical soil water response patterns were also observed, which were mainly attributed to root‐induced bypass flow. Focusing on the downslope region in the SF and non‐SF periods, the frequency of saturated zone generation at the soil‐bedrock interface decreased from 58% to 16%, but the frequency of bypass flow occurrence varied little. Saturated zone generation at the soil‐bedrock interface underneath the tree in both the SF and non‐SF periods suggests that trees are key locations for rainfall infiltration and that tree‐induced saturated zone generation should be considered carefully, even in conditions without stemflow supply.
Effect of detonation nanodiamonds on phagocyte activity
Authors: Karpukhin Alexey V. , Avkhacheva Nadezhda V. , Yakovlev Ruslan Yu. , Kulakova Inna I. , Yashin Valeriy A. , Lisichkin Georgiy V. , Safronova Valentina G.
Published: February 2011

Detonation ND (nanodiamond) holds much promise for biological studies and medical applications. Properties like size of particles, inclination for modification of their surface and unambiguous biocompatibility are crucial. Of prime importance is interaction between ND and immune cells, which supervise foreign intrusion into an organism and eliminate it. Neutrophils are more reactive in inflammatory response implementing cytotoxical arsenal including ROS (reactive oxygen species). The aim of the work was to estimate the ability of two ND samples (produced by Diamond Center and PlasmaChem) to keep the vitality of neutrophils from the inflammatory site. The ability of cells to generate ROS in the presence of ND particles is considered as indicating their biocompatibility. IR spectra and size of particles in the samples were characterized. Acid modification of ND was carried out to get the luminescent form. In the biological aspect, ND demonstrated up or down action, depending on the concentration, time and conditions of activation of cells. Weak action of ND in whole blood was obtained possibly owing to the ND adsorbed plasma proteins, which mask active functional groups to interact with the cell membrane. ND did not influence the viability of isolated inflammatory neutrophils in low and moderate concentrations and suppressed it in high concentrations (≥1 g/l). Addition of ND to the cell suspension initiated concentration‐dependent reaction to produce ROS similar to respiratory burst. ND up‐regulated response to bacterial formylpeptide, but up‐ and down‐modified (low or high concentrations, accordingly) response to such bacterial agents as OZ (opsonized zymosan), which neutrophils swallow up by oxygen‐dependent phagocytosis. Localization of the particles on the cell surface as into the cells was identified by monitoring the intrinsic fluorescence of oxidized ND. The various mechanisms that could account for penetration of ND particles into the cell are discussed. Common conclusion concerns compatibility of ND with living neutrophils from inflammatory site and their normal functioning for infection safeguard.
Grape seed procyanidin B2 inhibits advanced glycation end product‐induced endothelial cell apoptosis through regulating GSK3β phosphorylation
Authors: Li Bao‐ying , Li Xiao‐li , Gao Hai‐qing , Zhang Jian‐hua , Cai Qian , Cheng Mei , Lu Mei
Published: February 2011

To investigate the effects of GSPB2 (grape seed procyanidin B2) on the apoptosis of HUVECs (human umbilical endothelial cells) induced by AGEs (advanced glycation end products), HUVECs were treated with AGEs (200 μg/ml) in the presence or absence of GSPB2 (2.5, 5.0 and 10.0 μmol/l). Our findings showed that (i) AGEs induced HUVEC apoptosis and up‐regulated the expression of caspase‐3 activation and lactadherin and reduced the phosphorylation of GSK3β (glycogen synthase kinase 3β) at baseline. (ii) Treatment of HUVEC with GSPB2 significantly inhibited the cell apoptosis and the expression of caspase‐3 activation and lactadherin induced by AGEs. Moreover, GSPB2 inhibited intracellular reactive oxygen species in a dose‐dependent manner in AGEs‐treated cells as determined by flow cytometry. (iii) GSPB2 increased the phosphorylation of GSK3β of HUVEC in response to AGEs. These findings suggest that the signalling pathway involving phosphorylation of GSK3β and lactadherin might play a key role in the endothelial apoptosis. GSPB2 therapy could become an effective approach to battling AGEs‐induced endothelial apoptosis.
Effect of carbon nanotube coating of aligned nanofibrous polymer scaffolds on the neurite outgrowth of PC‐12 cells
Authors: Jin Guang‐Zhen , Kim Meeju , Shin Ueon Sang , Kim Hae‐Won
Published: February 2011

Neurite outgrowth from endogenous or transplanted cells is important for neural regeneration following nerve tissue injury. Modified substrates often provide better environments for cell adhesion and neurite outgrowth. This study was conducted to determine if MWCNT (multiwalled carbon nanotube)‐coated electrospun PLCL [poly (l‐lactic acid‐co‐3‐caprolactone)] nanofibres improved the neurite outgrowth of PC‐12 cells. To accomplish this, two groups, PC‐12 cells in either uncoated PLCL scaffolds or MWCNT‐coated PLCL scaffolds were cultured for 9 days. MWCNT‐coated PLCL scaffolds showed improved adhesion, proliferation and neurite outgrowth of PC‐12 cells. These findings suggest that MWCNT‐coated nanofibrous scaffolds may be an attractive platform for cell transplantation application in neural tissue engineering.
Polyploid tumour cells elicit paradiploid progeny through depolyploidizing divisions and regulated autophagic degradation
Authors: Erenpreisa Jekaterina , Salmina Kristine , Huna Anda , Kosmacek Elizabeth A. , Cragg Mark S. , Ianzini Fiorenza , Anisimov Alim P.
Published: February 2011

‘Neosis’ describes the process whereby p53 function‐deficient tumour cells undergo self‐renewal after genotoxic damage apparently via senescing ETCs (endopolyploid tumour cells). We previously reported that autophagic digestion and extrusion of DNA occurs in ETC and subsequently revealed that self‐renewal transcription factors are also activated under these conditions. Here, we further studied this phenomenon in a range of cell lines after genotoxic damage induced by gamma irradiation, ETO (etoposide) or PXT (paclitaxel) treatment. These experiments revealed that chromatin degradation by autophagy was compatible with continuing mitotic activity in ETC. While the actively polyploidizing primary ETC produced early after genotoxic insult activated self‐renewal factors throughout the polygenome, the secondary ETC restored after failed multipolar mitosis underwent subnuclei differentiation. As such, only a subset of subnuclei continued to express OCT4 and NANOG, while those lacking these factors stopped DNA replication and underwent degradation and elimination through autophagy. The surviving subnuclei sequestered nascent cytoplasm to form subcells, while being retained within the confines of the old ETC. Finally, the preformed paradiploid subcells became released from their linking chromosome bridges through autophagy and subsequently began cell divisions. These data show that ‘neotic’ ETC resulting from genotoxically damaged p53 function‐deficient tumour cells develop through a heteronuclear system differentiating the polyploid genome into rejuvenated ‘viable’ subcells (which provide mitotically propagating paradiploid descendents) and subnuclei, which become degraded and eliminated by autophagy. The whole process reduces aneuploidy in descendants of ETC.
Modulation of integrin α4β1 by ADAM28 promotes lymphocyte adhesion and transendothelial migration
Authors: McGinn Owen J , English William R. , Roberts Stephanie , Ager Ann , Newham Peter , Murphy Gillian
Published: February 2011

ADAMs (a disintegrin and metalloproteinase) are a family of type I transmembrane glycoproteins related to snake venom metalloproteases and disintegrins. They are regulatory proteins that modulate intercellular adhesion and the bioavailability of growth factors, and have been implicated in many disease states, including cancer, immunity and inflammation. One member of the ADAM family, ADAM28, has been reported to bind to the integrin α4β1 in humans; however, the distribution of ADAM28 and the biological consequences of ADAM28–α4β1 interactions are yet to be fully elucidated. The expression of ADAM28 in human and murine tissues was examined by multiple Affymetrix microarray analyses, real‐time RT—PCR (reverse transcription—PCR) and immunohistochemical staining. We found that ADAM28 has a relatively restricted expression pattern in mouse and human and is highly expressed in the B‐lymphocyte lineage, including chronic lymphocytic leukaemic B‐cells. The murine B‐lymphoma line L1‐2 and recombinant soluble murine ADAM28 were used to investigate ADAM28–α4β1 interactions. Our data reveal that ADAM28 binding to α4β1 is typical of integrin—ligand interactions, since it is attenuated by anti‐functional integrin antibodies, and is enhanced by Mn2+ and the integrin mAb (monoclonal antibody) 9EG7. However, a key finding was that soluble ADAM28 unexpectedly enhanced α4β1‐dependent cell adhesion to VCAM‐1 (vascular cell adhesion molecule‐1). In so doing ADAM28 was able to influence lymphocyte adhesion to, and migration through, endothelial monolayers, suggesting a physiological role for ADAM28 in regulating the specific spatial and temporal transendothelial migration of lymphocytes.
Infrared spectroscopy and effective modes analysis of the protonated water dimer H+(H2O)2 at room temperature under H/D substitution
Authors: Agostini Federica , Vuilleumier Rodolphe , Ciccotti Giovanni
Published: February 2011

We study the vibrational properties of the protonated water dimer and its deuterated forms at room temperature. Molecular dynamics simulations within the empirical valence bond (EVB) model are used to generate the vibrational spectra that are interpreted using the effective modes analysis (EMA). Quantum effects are taken into account through an effective parametrization of the EVB model. EMA allows for the assignment of the bands in the 1000 − 2000 cm−1 region of the protonated water dimer from the molecular dynamics trajectory. It is then found that although this system is very anharmonic the two main bands in this spectral region arise from a linear coupling between the asymmetric \documentclass[12pt]{minimal}\begin{document}$\mathrm O\mathrm H^{+}\mathrm O$\end{document}OH+O stretch and asymmetric bend of the two water molecules. This mixing explains the simulated band shifts upon isotopic substitution of the central proton or of the hydrogens of the two water molecules.
Infrared spectroscopy of small protonated water clusters at room temperature: An effective modes analysis
Authors: Agostini Federica , Vuilleumier Rodolphe , Ciccotti Giovanni
Published: February 2011

We perform infrared vibrational analysis on small protonated water clusters \documentclass[12pt]{minimal}\begin{document}$\mathrm H^{+}(\mathrm H_{2}\mathrm O)_{n}$\end{document}H+(H2O)n, with n = 2, …, 6, at room temperature. The absorption spectra are calculated based on classical trajectories obtained by the multistate empirical valence bond method. The analysis is carried out based on the effective modes analysis, which has been recently developed [Martinez et al., J. Chem. Phys. 125, 144106 (2006)] as generalization of the normal modes analysis. This technique enables us to decompose the full spectrum in maximally localized bands which are obtained by accounting for temperature and anharmonic effects. These effects are especially considered in the determination of the modes coupling. The spectra of the small clusters are interpreted by identifying the behavior of the excess charge, by understanding the role of hydrogen bonds, and by considering the effect of (micro-)solvation. Our results are presented by showing comparisons with other numerical methods and experimental measurements which are available in the literature.
Design and performance of a punch mechanism based pellet injector for alternative injection in the large helical device
Authors: Mishra J. S. , Sakamoto R. , Motojima G. , Matsuyama A. , Yamada H.
Published: February 2011

A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100–450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii Rc = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes.
Single-shot beam-position monitor for x-ray free electron laser
Authors: Tono Kensuke , Kudo Togo , Yabashi Makina , Tachibana Takeshi , Feng Yiping , Fritz David , Hastings Jerome , Ishikawa Tetsuya
Published: February 2011

We have developed an x-ray beam-position monitor for detecting the radiation properties of an x-ray free electron laser (FEL). It is composed of four PIN photodiodes that detect backscattered x-rays from a semitransparent diamond film placed in the beam path. The signal intensities from the photodiodes are used to compute the beam intensity and position. A proof-of-principle experiment at a synchrotron light source revealed that the error in the beam position is reduced to below 7 μm by using a nanocrystal diamond film prepared by plasma-enhanced chemical vapor deposition. Owing to high dose tolerance and transparency of the diamond film, the monitor is suitable for routine diagnostics of extremely intense x-ray pulses from the FEL.
Dynamics of ions produced by laser ablation of several metals at 193 nm
Authors: Baraldi G. , Perea A. , Afonso C. N.
Published: February 2011

This work reports the study of ion dynamics produced by ablation of Al, Cu, Ag, Au, and Bi targets using nanosecond laser pulses at 193 nm as a function of the laser fluence from threshold up to 15 J cm−2. An electrical (Langmuir) probe has been used for determining the ion yield as well as kinetic energy distributions. The results clearly evidence that ablation of Al shows unique features when compared to other metals. The ion yield both at threshold (except for Al, which shows a two-threshold-like behavior) and for a fixed fluence above threshold scale approximately with melting temperature of the metal. Comparison of the magnitude of the yield reported in literature using other wavelengths allows us to conclude its dependence with wavelength is not significant. The evolution of the ion yield with fluence becomes slower for fluences above 4–5 J cm−2 with no indication of saturation suggesting that ionization processes in the plasma are still active up to 15 J cm−2 and production of multiple-charged ions are promoted. This dependence is mirrored in the proportion of ions with kinetic energies higher than 200 eV. This proportion is not significant around threshold fluence for all metals except for Al, which is already 20%. The unique features of Al are discussed in terms of the energy of laser photons (6.4 eV) that is enough to induce direct photoionization from the ground state only in the case of this metal.
Electrical derivative measurement of quantum cascade lasers
Authors: Guo Dingkai , Cheng Liwei , Chen Xing , Choa Fow-Sen , Fan Jenyu , Worchesky Terry
Published: February 2011

The electrical derivative characteristics of quantum cascade lasers (QCLs) are investigated to test the QCL threshold, leakage current, and possibly explore carrier transport. QCL thresholds can be identified by searching for the slope peak of the first derivative of the I-V curves and can be further confirmed with its alignment to the peak of the second derivative of the I-V curves. Leakage current in QCLs with oxide-blocked ridge waveguides and buried heterostructure (BH) waveguides are studied and compared. The oxide-blocking structures provide the lowest leakage current although the capped-mesa-BH (CMBH) QCLs provide the toughest durability under highly stressful operations. The leakage current of CMBH QCLs are also compared at different temperatures.
Addressable subwavelength grids of confined light in a multislotted nanoresonator
Authors: Cluzel B. , Foubert K. , Lalouat L. , Dellinger J. , Peyrade D. , Picard E. , Hadji E. , de Fornel F.
Published: February 2011

In this letter, we fabricate a multislotted optical nanoresonator with several spatial field distributions which are all addressable by the wavelength. The reported structure consists in an array of evanescently coupled single mode photonic crystal nanocavities. By using a scanning near-field optical microscope, we quantify the morphology of the different optical mode volumes and show that they consist in grids of light confined at the subwavelength scale.
Intensity analysis of overlapped discrete and continuous absorption by spectral simulation: The electronic transition moment for the B–X system in I2
Authors: Tellinghuisen Joel
Published: February 2011

The spectrum of I2 is examined anew in the wavelength region 520–640 nm, where discrete absorption in the B–X transition is prominent. The spectrum is recorded with high quantitative precision at moderate resolution (0.1 nm) and is analyzed by least-squares spectral simulation, yielding the B–X electronic transition strength |μe|2 with unprecedented precision (<2% relative standard error) over most of the studied region. The analysis also yields directly new estimates of the continuous absorption in this region, which support previous assessments of the A ← X transition but lower the C(1Πu) ← X transition strength by 25%. The new analysis method is applicable to any situation where the discrete spectrum can be simulated reliably.
Role of dipole–dipole interaction on enhancing Brownian coagulation of charge-neutral nanoparticles in the free molecular regime
Authors: Zhang Yiyang , Li Shuiqing , Yan Wen , Yao Qiang , Tse Stephen D.
Published: February 2011

In contrast to van der Waals (vdW) forces, Coulombic dipolar forces may play a significant role in the coagulation of nanoparticles (NPs) but has received little or no attention. In this work, the effect of dipole–dipole interaction on the enhancement of the coagulation of two spherically shaped charge-neutral TiO2 NPs, in the free molecular regime, is studied using classical molecular dynamics (MD) simulation. The enhancement factor is evaluated by determining the critical capture radius of two approaching NPs for different cases of initial dipole direction with respect to path (parallel/perpendicular) and orientation with respect to each other (co-orientated/counterorientated). As particle diameter decreases, the enhancement of coagulation is augmented as the ratio of dipole–dipole force to vdW force becomes larger. For 2-nm TiO2 NPs at 273 K, the MD simulation predicts an average enhancement factor of about 8.59, which is much greater than the value of 3.78 when only the vdW force is considered. Nevertheless, as temperature increases, the enhancement factor due to dipole–dipole interaction drops quickly because the time-averaged dipole moment becomes small due to increased thermal fluctuations (in both magnitude and direction) of the instantaneous dipole moment.
The visible extinction peaks of Ag nanohelixes: A periodic effective dipole model
Authors: Zhang Z.-Y. , Zhao Y.-P.
Published: February 2011

Using the discrete dipole approximation method, two visible extinction peaks are found for Ag nanohelixes. Both of them redshift periodically in an approximate half pitch with the helix height and redshift linearly with the helix diameter and pitch height. At the two absorbance peaks, an integer number of E-field maxima occur along the helix. These field maxima could be treated as results of collective electron oscillations by periodic effective dipoles within a half pitch along the helix. The wavelengths of the absorbance peaks are found to scale with the effective dipole length, which is consistent with the periodic structure of the helix.
Fast quantum dot single photon source triggered at telecommunications wavelength
Authors: Rivoire Kelley , Buckley Sonia , Majumdar Arka , Kim Hyochul , Petroff Pierre , Vučković Jelena
Published: February 2011

We demonstrate a quantum dot single photon source at 900 nm triggered at 100 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The quantum dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs quantum dot. Our result suggests a path toward the realization of telecommunications wavelength-compatible quantum dot single photon sources with speeds exceeding 1 GHz.
Carbon doped InAlAs/InGaAs/InAs heterostructures: Tuning from n- to p-doping
Authors: Hirmer M. , Schuh D. , Wegscheider W.
Published: February 2011

We fabricated carbon doped InAs/InxGa1−xAs/InxAl1−xAs heterostructures, which show p-type and n-type conductivity for different In contents. Two-dimensional hole gas in a structure with x=0.75 has been prepared in the ternary compound, despite the fact that carbon as an n-type dopant in InAs exhibits electron conductivity in InxGa1−xAs and InxAl1−xAs compounds with high indium content. A special doping design has been employed to obtain hole conductivity. As a result, the conductivity can be tuned from n-type to p-type with the In content and with different doping profiles in these structures.
Electric-field-induced strain mechanisms in lead-free 94%(Bi1/2Na1/2)TiO3–6%BaTiO3
Authors: Simons Hugh , Daniels John , Jo Wook , Dittmer Robert , Studer Andrew , Avdeev Maxim , Rödel Jürgen , Hoffman Mark
Published: February 2011

High resolution neutron diffraction has been used to investigate the structural origin of the large electric-field-induced remanent strain in 94(Bi1/2Na1/2)TiO3–6BaTiO3 ceramics. The virgin material was found to be a mixture of near-cubic phases with slight tetragonal and rhombohedral distortions of a0a0c+ and a−a−a− octahedral tilt type, respectively. Application of an electric field of 4.57 kV/mm transformed the sample to a predominantly rhombohedral a−a−a− modification with a significantly higher degree of structural distortion and a pronounced preferred orientation of the c-axis along the field direction. These electric field-induced structural effects contribute significantly to the macroscopic strain and polarization of this system.
Schottky contacts on differently grown n-type ZnO single crystals
Authors: Kolkovsky Vl. , Scheffler L. , Hieckmann E. , Lavrov E. V. , Weber J.
Published: February 2011

The preparation and characterization of Schottky contacts on differently grown n-type ZnO crystals was studied. We demonstrate that depending on the crystal growth process different procedures of surface treatment should be used to achieve good Schottky contacts. A treatment in a dc-hydrogen plasma enables us to fabricate Schottky contacts on hydrothermally grown ZnO, whereas a similar treatment of the vapor phase and melt grown ZnO resulted in the reduction in the diode rectification ratio. In the later samples a treatment in H2O2 significantly improves the quality of Schottky contacts. The origin of the different behavior will be discussed.