bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence and risk factors of depressive symptoms in latest life—results of the Leipzig Longitudinal Study of the Aged (LEILA 75+)
Authors: Luppa Melanie , Sikorski Claudia , Luck Tobias , Weyerer Siegfried , Villringer Arno , König Hans‐Helmut , Riedel‐Heller Steffi G.
Published: April 2011

Introduction

Because the oldest old will be the fastest‐growing age group in the future and information about epidemiology of depressive symptoms in latest life is scarce, the present study aims at determining the age‐specific and gender‐specific prevalence rates and risk factors of depressive symptoms in latest life.

Methods

As part of the Leipzig Longitudinal Study of the Aged (LEILA 75+), a population‐based sample of 1 006 individuals aged 75 years and older were interviewed on socio‐demographic, clinical and psychometric variables. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (cut‐off score ≥16); mild cognitive impairment (MCI) was diagnosed according to criteria of the International Working Group on MCI. Factors associated with depressive symptoms were determined with multiple logistic regression models.

Results

Of the overall sample, 38.2% (95% confidence interval, CI 35.2–41.2) were classified as depressed. In the full multivariate model, the following variables were significantly associated with depressive symptoms: divorced or widowed marital status, low educational level, poor self‐rated health status, functional impairment, multi‐domain MCI, stressful life events and poor social network. All variables but MCI remained significant correlates of depressive symptoms in the parsimonious model.

Discussion

Because depressive symptoms are common in oldest age and associated with broad categories of risk factors, latest‐life depression represents an important public health issue. Employment of comprehensive geriatric assessment to ascertain depressive symptoms and its concomitants could help to improve treatment success. Copyright © 2011 John Wiley & Sons, Ltd.
Halogenation reactions of a ditelluride having bulky aryl groups leading to the formation of organotellurium halides
Authors: Sasamori Takahiro , Sugamata Koh , Tokitoh Norihiro
Published: April 2011

Halogenation reactions of BbtTe‐TeBbt (Bbt; 2,6‐bis[bis(trimethylsilyl)methyl]‐4‐[tris (trimethylsilyl)methyl]phenyl) with SO2Cl2, Br2, and I2 were examined. When 1 equiv of the reagents were used, the corresponding tellurium monohalides were obtained as stable crystalline compounds. Although iodination reaction of BbtTe‐TeBbt using 3 equiv of I2 afforded BbtTeI, treatment of BbtTe‐TeBbt with 3 equiv of SO2Cl2 and Br2 gave the corresponding tellurium trihalides, BbtTeX3(X = Cl, Br), as stable crystalline compounds. Characterization of the obtained tellurium mono‐ and trihalides was achieved by the spectroscopic and crystallographic analyses, together with theoretical calculations. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:405–411, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20698
Cyclobutadiene to tetrahedrane: Valence isomerization induced by one‐electron oxidation
Authors: Nakamoto Masaaki , Inagaki Yusuke , Ochiai Tatsumi , Tanaka Masanobu , Sekiguchi Akira
Published: April 2011

A new procedure for synthesizing tetrakis(trimethylsilyl)tetrahedrane from tetrakis(trimethylsilyl)cyclobutadiene is reported. Valence isomerization of cyclobutadiene to tetrahedrane induced by one‐electron oxidation has been developed by the addition of tris(pentafluorophenyl)borane as an oxidant. This new method has great synthetic advantages for easy, quick, and high‐yielding reaction to achieve gram‐order‐scale synthesis of tetrakis(trimethylsilyl)tetrahedrane. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:412–416, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20699
An improved genetic programming to SSM/I estimation typhoon precipitation over ocean
Authors: Chen Li , Yeh Keh‐Chia , Wei Hsiao‐Ping , Liu Gin‐Rong
Published: April 2011

This article proposes an improved multi‐run genetic programming (GP) and applies it to estimate the typhoon rainfall over ocean using multi‐variable meteorological satellite data. GP is a well‐known evolutionary programming and data mining method used to automatically discover the complex relationships among nonlinear systems. The main advantage of GP is to optimize appropriate types of function and their associated coefficients simultaneously. However, the searching efficiency of traditional GP can be decreased by the complex structure of parse tree to represent the multiple input variables. This study processed an improvement to enhance escape ability from local optimums during the optimization procedure. We continuously run GP several times by replacing the terminal nodes at the next run with the best solution at the current run. The current method improves GP, obtaining a highly nonlinear meaningful equation to estimate the rainfall. In the case study, this improved GP (IGP) described above combined with special sensor microwave imager (SSM/I) seven channels was employed. These results are then verified with the data from four offshore rainfall stations located on islands around Taiwan. The results show that the IGP generates sophisticated and accurate multi‐variable equation through two runs. The performance of IGP outperforms the traditional multiple linear regression, back‐propagated network (BPN) and three empirical equations. Because the extremely high values of precipitation rate are quite few and the number of zero values (no rain) is very large, the underestimations of heavy rainfall are obvious. A simple genetic algorithm was therefore used to search for the optimal threshold value of SSM/I channels, detecting the data of no rain. The IGP with two runs, used to construct an appropriate mathematical function to estimate the precipitation, can obtain more favourable results from estimating extremely high values. Copyright © 2011 John Wiley & Sons, Ltd.
Lead exposure and poisoning of songbirds using the Coeur d'Alene River Basin, Idaho, USA
Authors: Hansen James A , Audet Daniel , Spears Brian L , Healy Kate A , Brazzle Roy E , Hoffman David J , Dailey Anne , Beyer W Nelson
Published: April 2011

Previous studies have found widespread Pb poisoning of waterfowl in the Coeur d'Alene River Basin in northern Idaho, USA, which has been contaminated by mining and smelting activities. We studied the exposure of ground-feeding songbirds to Pb, sampling 204 American robins (Turdus migratorius), song sparrows (Melospiza melodia), and Swainson's thrushes (Catharus ustulatus) throughout the basin. These songbirds had mean blood Pb concentrations (mg/kg, dry weight) of less than 0.19 at a reference area (25 mg Pb/kg soil), 1.09 at moderately contaminated sites (170 to 1300 mg Pb/kg soil), and 2.06 at highly contaminated sites (2000 to 5000 mg Pb/kg soil). Based on guidelines for evaluating blood Pb in birds, 6% of robins from the highly contaminated sites had background concentrations, 24% were subclinically poisoned, 52% were clinically poisoned, and 18% were severely clinically poisoned with Pb. Blood Pb concentrations were lower in song sparrows than in robins and lowest in Swainson's thrushes. More than half of the robins and song sparrows from all contaminated sites and more than half of the Swainson's thrushes from highly contaminated sites showed at least 50% inhibition of the activity of the enzyme δ-aminolevulinic acid dehydratase (ALAD), commonly used as a measure of exposure to Pb. The highest hepatic Pb concentration of 61 mg/kg (dry weight) was detected in a song sparrow. Using Al as a marker for soil in songbird ingesta, we estimated average soil ingestion rates as 20% in robins, 17% in song sparrows, and 0.7% in Swainson's thrushes. Soil Pb in ingesta accounted for almost all of the songbirds' exposure to Pb. Based on these results, it is recommended that ecological risk assessments of ground-feeding songbirds at contaminated sites include soil ingestion as a pathway of exposure to Pb. Integr Environ Assess Manag 2011;7:587–595. © 2011 SETAC
Is God in the details? A reexamination of the role of religion in economic growth
Authors: Durlauf Steven N. , Kourtellos Andros , Tan Chih Ming
Published: April 2011

Barro and McCleary (2003, Religion and economic growth across countries. American Journal of Sociology 68: 760–781) is a key research contribution in the new literature exploring the macroeconomic effects of religious beliefs. This paper represents an effort to evaluate the strength of their claims. We evaluate their results in terms of replicability and robustness. Overall, their analysis generally meets the standard of statistical replicability, though not perfectly. On the other hand, we do not find that their results are robust to changes in their baseline statistical specification. When model‐averaging methods are employed to integrate information across alternative statistical specifications, little evidence survives that religious variables help to predict cross‐country income differences. Copyright © 2011 John Wiley & Sons, Ltd.
Morphological and mineral analysis of dental enamel after erosive challenge in gastric juice and orange juice
Authors: Braga Sheila Regina Maia , De Faria Dalva Lúcia araújo , De Oliveira Elisabeth , Sobral Maria Angela Pita
Published: April 2011

This study evaluated and compared in vitro the morphology and mineral composition of dental enamel after erosive challenge in gastric juice and orange juice. Human enamel specimens were submitted to erosive challenge using gastric juice (from endoscopy exam) (n = 10), and orange juice (commercially‐available) (n = 10), as follows: 5 min in 3 mL of demineralization solution, rinse with distilled water, and store in artificial saliva for 3 h. This cycle was repeated four times a day for 14 days. Calcium (Ca) loss after acid exposure was determined by atomic emission spectroscopy. The presence of carbonate (CO) and phosphate (PO) in the specimens was evaluated before and after the erosive challenge by FT‐Raman spectroscopy. Data were tested using t‐tests (P < 0.05). Morphology of enamel was observed in scanning electron microscopy (SEM). The mean loss of Ca was: 12.74 ± 3.33 mg/L Ca (gastric juice) and 7.07 ± 1.44 mg/L Ca (orange juice). The analysis by atomic emission spectroscopy showed statistically significant difference between erosive potential of juices (P = 0.0003). FT‐Raman spectroscopy found no statistically significant difference in the ratio CO/PO after the erosive challenge. The CO/PO ratios values before and after the challenge were: 0.16/0.17 (gastric juice) (P = 0.37) and 0.18/0.14 (orange juice) (P = 0.16). Qualitative analysis by SEM showed intense alterations of enamel surface. The gastric juice caused more changes in morphology and mineral composition of dental enamel than orange juice. The atomic emission spectroscopy showed to be more suitable to analyze small mineral loss after erosive challenge than FT‐Raman. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.
MRT letter: Real time and in situ imaging the reversible evolution of ethanol vapor condensed on mica surface
Authors: Zhang Donghua , Zhang Chen , Zhang Fuchun , Hu Jun
Published: April 2011

The reversible adsorption and desorption of ethanol vapor on mica surface at ambient temperature were investigated in situ with time‐evolution by Vibrating Scanning Polarization Force Microscopy (VSPFM). At temperature 20°C and relative humidity 20%, ethanol vapor condensed and formed clusters on the freshly cleaved mica. These clusters expanded to a network structure and later formed a full film shown by continuous VSPFM imaging. The film broke into pieces and desorbed completely if in unsaturated condition. The film showed different apparent heights when different biases were used in VSPFM study, indicated polarized orientation of the ethanol molecules on the mica surface. It is a process of hours for the clusters or network structures to form a film on mica, which demonstrated that vapor ethanol molecule is not so easy to precipitate on mica as ethanol molecule in liquid stage. Microsc. Res. Tech. 2011. © 2011 Wiley‐Liss, Inc.
Spring Arctic sea ice as an indicator of North American summer rainfall
Authors: Song Mirong , Liu Jiping , Wang Chunyi
Published: April 2011

Associations between the spring Arctic sea ice concentration (SIC) and North American summer rainfall were discussed using the singular value decomposition analysis. Results show that a reduced SIC in the North Atlantic and Pacific sectors of the Arctic, and an enhanced SIC in much of the central Arctic Basin and Beaufort Sea, are accompanied by dry conditions over the western United States, the northern Great Plains, the Midwest, westernmost Canada, and central and eastern Greenland, and wet conditions over the southern United States, Alaska, northern Canada, and western Greenland. Atmospheric circulation anomalies associated with the SIC variability show two wave‐train structures, which are persistent from spring to summer, leading to the identified relationship between the spring Arctic SIC and North American summer rainfall. This relationship indicates a potential long‐term outlook for the North American summer rainfall as the decline of the spring sea ice in the north Atlantic and Pacific sectors of the Arctic is expected to continue as climate warms. Copyright © 2011 Royal Meteorological Society
Surgical anatomy of transcanal endoscopic approach to the tympanic facial nerve
Authors: Marchioni Daniele , Alicandri‐Ciufelli Matteo , Piccinini Alessia , Genovese Elisabetta , Monzani Daniele , Tarabichi Muaaz , Presutti Livio
Published: April 2011

Objectives/Hypothesis:

Until recently, tympanic facial nerve surgery had been performed using microscopic approaches, but in recent years, exclusive endoscopic approaches to the middle ear have increasingly been used, particularly in cholesteatoma surgery. The aim of this report was to illustrate the surgical anatomy of the facial nerve during an exclusive endoscopic transcanal approach.

Study Design:

Retrospective video review of cadaveric dissections and operations on living patients in a tertiary university referral center.

Methods:

Between November 2008 and July 2010, a total of 12 endoscopic cadaveric dissections were performed by an exclusive endoscopic transcanal approach. All dissections were recorded and stored in a database. In July 2010, video recordings from those dissections were reviewed, and the anatomic variations and accessibility of the tympanic facial nerve were studied and noted. Two further video recordings from living patients affected by middle ear chronic disease were also included in our study.

Results:

In all 14 subjects, the transcanal endoscopic approach guaranteed direct access to the entire tympanic segment of the facial nerve after ossicular chain removal, allowing decompression of the nerve from the geniculate ganglion and the greater petrosal nerve to the second genu of the facial nerve. As in microscopic techniques, the cochleariform process and transverse crest (cog) may represent useful landmarks.

Conclusions:

The tympanic facial nerve can be thoroughly visualized by an exclusive endoscopic transcanal approach, even in poorly accessible regions such as the second genu and geniculate ganglion. Further clinically based reports may strengthen our preliminary results.
Hear no evil—see no evil: political advertising in Ireland
Authors: Rafter Kevin
Published: April 2011

This article examines the regulation of political advertising on television and radio in Ireland where a restrictive set of rules prevent political parties and lobby groups from using the broadcast medium to communicate directly with the public. The current regime does provide qualifying political parties with access to a system of broadcasts during election and referendum campaigns, a system that is not available to lobby groups and other representative bodies. Evidence is presented to suggest that subject to certain defined rules, there is a public openness to some modification of the current outright prohibition on political advertising in Ireland. Copyright © 2011 John Wiley & Sons, Ltd.
The social cost of trading: Measuring the increased damages from sulfur dioxide trading in the United States
Authors: Henry David D. , Muller Nicholas Z. , Mendelsohn Robert O.
Published: April 2011

The sulfur dioxide (SO2) cap and trade program established in the 1990 Clean Air Act Amendments is celebrated for reducing abatement costs ($0.7 to $2.1 billion per year) by allowing emissions allowances to be traded. Unfortunately, places with high marginal costs also tend to have high marginal damages. Ton‐for‐ton trading reduces emissions in low damage areas (rural) while increasing emissions in high damage areas (cities). From 2000 to 2007, conservative estimates of the value of mortality risk suggest that trades increased damages from $0.8 to $1.1 billion annually relative to the initial allowance allocation and from $1.5 to $1.9 billion annually relative to a uniform performance standard. With U.S. Environmental Protection Agency (USEPA) values, trades increased damages from $2.4 to $3.2 billion annually compared to the initial allowance allocation and from $4.4 to $5.4 billion compared to a uniform performance standard. It is not clear that the ton‐for‐ton SO2 cap and trade program is actually more efficient than comparable command and control programs. The trading program needs to be modified so that tons are weighted by their marginal damage. © 2011 by the Association for Public Policy Analysis and Management.
Initial testing (Stage 1) of AT13387, an HSP90 inhibitor, by the pediatric preclinical testing program
Authors: Kang Min H. , Reynolds C. Patrick , Houghton Peter J. , Alexander Denise , Morton Christopher L. , Kolb E. Anders , Gorlick Richard , Keir Stephen T. , Carol Hernan , Lock Richard , Maris John M. , Wozniak Amy , Smith Malcolm A.
Published: April 2011

AT13387, a non‐geldanamycin inhibitor of heat‐shock protein 90 (HSP90), was tested against the PPTP in vitro panel (1.0 nM to 10 µM) and against the PPTP in vivo panels (40 or 60 mg/kg) administered orally twice weekly. In vitro AT13387 showed a median EC50 value of 41 nM and exhibited activity consistent with a cytotoxic effect. In vivo AT13387 induced significant differences in EFS distribution compared to controls in 17% evaluable solid tumor xenografts, but in none of the ALL xenografts. No objective tumor responses were observed. In vivo AT13387 demonstrated only modest single agent activity. Pediatr Blood Cancer 2012; 59: 185–188. © 2011 Wiley Periodicals, Inc.
Bi‐allelic deletions within 13q14 and transient trisomy 21 with absence of GATA1s in pediatric acute megakaryoblastic leukemia
Authors: Massaro Stephanie A. , Bajaj Renu , Pashankar Farzana D. , Ornstein Deborah , Gallagher Patrick G. , Krause Diane S. , Li Peining
Published: April 2011

Oligonucleotide array comparative genomic hybridization, karyotype and fluorescence in situ hybridization analyses were employed to delineate the cytogenetic abnormalities in a case of pediatric acute megakaryoblastic leukemia. Here we present a unique genetic profile that includes bi‐allelic deletions within 13q14, where the retinoblastoma tumor suppressor gene (RB1) resides, as well as isolated trisomy 21 without a concomitant mutation in the hematopoietic transcription factor GATA1s and translocation (17;22), that does not involve the megakaryoblastic leukemia 1 (MKL1) gene located on chromosome 22. Alteration of the RB1 gene is most likely the critical leukemogenic event in this patient. Pediatr Blood Cancer 2011; 57: 516–519. © 2011 Wiley‐Liss, Inc.
Rapid Separation and Identification of Anthocyanins from Flowers of Viola yedoensis and V. prionantha by High‐performance Liquid Chromatography–Photodiode Array Detection–Electrospray Ionisation Mass Spectrometry
Authors: Zhang Jie , Wang Liang‐Sheng , Gao Jin‐Ming , Xu Yan‐Jun , Li Lian‐Fang , Li Chong‐Hui
Published: April 2011

Introduction

Anthocyanins are important plant secondary metabolites. They show strong antioxidant activities and have potential as anti‐cancer agents. Viola yedoensis and V. prionantha are traditional Chinese medicines and ornamental plants. However, the anthocyanin compositions of these two species are still unresolved.

Objective

To develop a rapid and reliable high‐performance liquid chromatography (HPLC) method for the separation and identification of anthocyanins from V. yedoensis and V. prionantha.

Methodology

Samples were extracted in methanol–water–formic acid–TFA (70:27:2:1, v/v). HPLC analysis was done on a C18 column (TSK‐GEL ODS‐80Ts: 150 × 4.6 mm i.d.). Four solvent systems were tested to optimise the separation of anthocyanins using different gradient separation systems. HPLC‐photodiode array detection (DAD) coupled to electrospray ionisation mass spectrometry (ESI‐MS) was used to carry out the comprehensive characterisation of anthocyanins.

Results

Fourteen anthocyanins were characterised within 40 min with satisfactory peak resolution by a gradient composed of 10% aqueous formic acid and formic acid–acetonitrile–water (10:40:50, v/v). The calibration curve showed an excellent linear regression (r2 = 0.9995) and low intra‐ and inter‐day variations (RSD < 3.67%). The detected anthocyanins derived from Dp, Cy, Pt, Mv and Pn, could be divided into three groups: non‐acylated glycosides, acetylglycosides and coumaroylglycosides. Anthocyanins distribution exhibited remarkable differences in aglycone levels and acylation patterns.

Conclusion

The optimised method was successfully applied for the analysis of 14 anthocyanins from V. yedoensis and V. prionantha. The identification of anthocyanin constitutions is valuable for breeding and will open up new prospects for their medicinal application. Copyright © 2011 John Wiley & Sons, Ltd.
Proteomics of the oxidative stress response induced by hydrogen peroxide and paraquat reveals a novel AhpC‐like protein in Pseudomonas aeruginosa
Authors: Hare Nathan J. , Scott Nichollas E. , Shin Eun Hye H. , Connolly Angela M. , Larsen Martin R. , Palmisano Giuseppe , Cordwell Stuart J.
Published: April 2011

Pseudomonas aeruginosa is a ubiquitous pathogen most typically associated with wound infections, but also the main cause of mortality in patients suffering from cystic fibrosis (CF). The ability to adapt to oxidative stress associated with host immune defense may be one mechanism by which P. aeruginosa establishes infection in the cystic fibrosis lung and eventually out‐competes other pathogenic bacteria to persist into chronic infection. We utilized a proteomics approach to identify the proteins associated with the oxidative stress response of P. aeruginosa PAO1 to hydrogen peroxide and superoxide‐inducing paraquat. 2‐DE and MS allowed for the identification of 59 and 58 protein spots that were statistically significantly altered following H2O2 and paraquat treatment, respectively. We observed a unique mass and pI pattern for alkylhydroperoxide reductase C (AhpC) that was replicated by hypothetical protein PA3529 following treatment with 10 mM H2O2. AhpC belongs to the 2‐Cys peroxiredoxin family and is a redox enzyme responsible for removing peroxides in bacterial cells. MS analysis showed that PA3529 was altered by the formation of a dimer via a disulfide bond in a manner analogous to that known for AhpC, and by cysteine overoxidation to Cys‐sulfonic acid (SO3H) postoxidative stress. PA3529 is therefore a functional AhpC paralog expressed under H2O2 stress. Following paraquat‐induced oxidative stress, we also observed the overabundance and likely oxidative modification of a second hypothetical antioxidant protein (PA3450) that shares sequence similarity with 1‐Cys peroxiredoxins. Other induced proteins included known oxidative stress proteins (superoxide dismutase and catalase), as well as those involved in iron acquisition (siderophore biosynthesis and receptor proteins FpvA and FptA) and hypothetical proteins, including others predicted to be antioxidants (PA0848). These data suggest that P. aeruginosa contains a plethora of novel antioxidant proteins that contribute to its increased resistance against oxidative stress.
LOPA onions: Peeling back the outer layers
Authors: Wasileski Robert F. , Henselwood Fred
Published: April 2011

Layer of protection analysis (LOPA) has quickly gained acceptance in the chemical processing industries and has risen to be one of the leading risk assessment techniques used for process safety studies. LOPA generally uses more rigor and science than what is encountered with qualitative risk assessments, while still not becoming overly onerous when compared with detailed quantitative risk assessments. In the interest of balancing time and resources against science and accuracy, certain tradeoffs and assumptions are made within the LOPA assessment. In turn, these tradeoffs and assumptions can lead to inaccurate conclusions.

For example, one issue that arises is with the treatment of protection layers associated with mitigation of consequences. LOPA teams have a choice to account for mitigation layers in the consequence assignment or alternatively treat these layers as independent protection layers (IPLs). Although this may appear to be an inconsequential decision, it can in fact result in very different conclusions. In the course of treating mitigation layers as IPLs, organizations must ensure the necessary inspection, testing, and preventive maintenance practices are in place for these layers. Furthermore, recognizing this dichotomy in treatment, one can also show that these mitigation layers should be designed so as to achieve a balance between consequence reduction and desired reliability.

This article discusses alternative treatments of risk mitigation layers that are commonly applied by LOPA teams and demonstrates their impacts through case studies. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Primary reformer tubes failure due to corrosion attack
Authors: Turi Iftikhar H.
Published: April 2011

For the last 30 years, reformer tubes are gone through numerous changes in manufacturing processes and material of construction to improve performance and reliability. To increase plant throughout Qatar Fertilizer Company replaced the old HK40 tubes with HP modified alloy but within 24 months of operation, unexpected corrosion attack was observed on some of the reformer tubes. In this article, the potential root cause of the tube damage and remediation actions has been discussed. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011.
Germination responses of three grassland species differ between native and invasive origins
Authors: Beckmann Michael , Bruelheide Helge , Erfmeier Alexandra
Published: April 2011

The germination stage is critical in plant life‐history and is also a key process during the expansion of species’ ranges into new environments. In this study we investigated the germination patterns of three plant species (Achillea millefolium,Hieracium pilosellaandHypericum perforatum) that are invasive to New Zealand (NZ) and native to Central Europe. We asked whether the species show differences in germination temperature requirements, germination speed and maximum germination rates, and thus, whether they display evidence of adaptation to different conditions in the invasive range. Seeds from three populations per species and region were subjected to three different temperature regimes to compare germination rates among origins and across temperature conditions. ForAchillea millefoliumandHypericum perforatum, germination rates were significantly higher for invasive NZ provenances than for native German ones. Seeds from invasive populations of all three species displayed increased maximum germination at medium temperature conditions when compared to native populations, which indicates altered germination strategies in the invaded range. Changes in temporal development patterns were most conspicuous for invasiveHieracium pilosellaandHypericum perforatumpopulations. These findings imply that adaptation in germination patterns towards different climatic conditions in invasive populations has occurred. Our study emphasises the importance of the germination stage during plant invasion and its role in explaining range expansion of these species.
Effect of Some Transition Metals on the Monolayer Oxidation of Methyl Linoleate
Authors: Koprucuoglu Yasemin , Calikoglu Eda , Tekin Aziz , Hammond Earl G.
Published: April 2011

Methyl linoleate was deposited as a monolayer on a silica gel control and on silica gel supplemented with double or quadruple the control's amount of the transition metal ions (TMI) iron, copper, vanadium or titanium. The treatments were oxidized at 25 °C, and periodically samples were examined for peroxide values (PV) and by gas chromatography for oxidation products (GC). Comparison of the treatments revealed that: Surface oxidation on silica gel owes its high rate to TMI, which may speed free radical initiation. Epoxidation is catalyzed by the presence of vanadium and titanium. Scission products (SP) and unrecovered mass increased with the extent of oxidation probably because of increased free radical life time.
Low Rossby limiting dynamics for stably stratified flow with finite Froude number
Authors: WINGATE BETH A. , EMBID PEDRO , HOLMES-CERFON MIRANDA , TAYLOR MARK A.
Published: April 2011

In this paper, we explore the strong rotation limit of the rotating and stratified Boussinesq equations with periodic boundary conditions when the stratification is order 1 ([Rossby number] Ro = ε, [Froude number] Fr = O(1), as ε → 0). Using the same framework of Embid & Majda (Geophys. Astrophys. Fluid Dyn., vol. 87, 1998, p. 1), we show that the slow dynamics decouples from the fast. Furthermore, we derive equations for the slow dynamics and their conservation laws. The horizontal momentum equations reduce to the two-dimensional Navier–Stokes equations. The equation for the vertically averaged vertical velocity includes a term due to the vertical average of the buoyancy. The buoyancy equation, the only variable to retain its three-dimensionality, is advected by all three two-dimensional slow velocity components. The conservation laws for the slow dynamics include those for the two-dimensional Navier–Stokes equations and a new conserved quantity that describes dynamics between the vertical kinetic energy and the buoyancy. The leading order potential enstrophy is slow while the leading order total energy retains both fast and slow dynamics. We also perform forced numerical simulations of the rotating Boussinesq equations to demonstrate support for three aspects of the theory in the limit Ro → 0: (i) we find the formation and persistence of large-scale columnar Taylor–Proudman flows in the presence of O(1) Froude number; after a spin-up time, (ii) the ratio of the slow total energy to the total energy approaches a constant and that at the smallest Rossby numbers that constant approaches 1 and (iii) the ratio of the slow potential enstrophy to the total potential enstrophy also approaches a constant and that at the lowest Rossby numbers that constant is 1. The results of the numerical simulations indicate that even in the presence of the low wavenumber white noise forcing the dynamics exhibit characteristics of the theory.
Impact of high-temperature stress on rice plant and its traits related to tolerance
Authors: SHAH F. , HUANG J. , CUI K. , NIE L. , SHAH T. , CHEN C. , WANG K.
Published: April 2011

The predicted 2–4°C increment in temperature by the end of the 21st Century poses a threat to rice production. The impact of high temperatures at night is more devastating than day-time or mean daily temperatures. Booting and flowering are the stages most sensitive to high temperature, which may sometimes lead to complete sterility. Humidity also plays a vital role in increasing the spikelet sterility at increased temperature. Significant variation exists among rice germplasms in response to temperature stress. Flowering at cooler times of day, more pollen viability, larger anthers, longer basal dehiscence and presence of long basal pores are some of the phenotypic markers for high-temperature tolerance. Protection of structural proteins, enzymes and membranes and expression of heat shock proteins (HSPs) are some of the biochemical processes that can impart thermo-tolerance. All these traits should be actively exploited in future breeding programmes for developing heat-resistant cultivars. Replacement of heat-sensitive cultivars with heat-tolerant ones, adjustment of sowing time, choice of varieties with a growth duration allowing avoidance of peak stress periods, and exogenous application of plant hormones are some of the adaptive measures that will help in the mitigation of forecast yield reduction due to global warming.
The Problematic Past in the Work of Charles Sheeler, 1917–1927
Authors: CORBETT DAVID PETERS
Published: April 2011

This article examines the place of the past in Charles Sheeler's photographs and paintings made in Doylestown, Pennsylvania, around 1917, in New York City during the 1920s, and in the short film of New York, Manhatta (1921), which he made with the photographer Paul Strand. It situates these works in the context of the scholarship on Sheeler and on the art of New York in the early twentieth century, in particular that of the Ashcan School and of visual representation which attends to the architectural fabric of the city in preference to depicting its inhabitants. The article argues that although the scholarship has identified Sheeler's interest in making connections with the American past, it has not recognized the fraught nature of that relationship. By looking at the Doylestown and New York pictures, the analysis demonstrates how the problematic status of the past for Sheeler appears in these works as hauntings and absences.
Moving-mesh hydrodynamics with the AREPO code
Authors: Springel Volker
Published: April 2011

At present, hydrodynamical simulations in computational star formation are either carried out with Eulerian mesh-based approaches or with the Lagrangian smoothed particle hydrodynamics (SPH) technique. Both methods differ in their strengths and weaknesses, as well as in their error properties. It would be highly desirable to find an intermediate discretization scheme that combines the accuracy advantage of mesh-based methods with the automatic adaptivity and Galilean invariance of SPH. Here we briefly describe the novel AREPO code which achieves these goals based on a moving unstructured mesh defined by the Voronoi tessellation of a set of discrete points. The mesh is used to solve the hyperbolic conservation laws of ideal hydrodynamics with a finite volume approach, based on a second-order unsplit Godunov scheme with an exact Riemann solver. A particularly powerful feature is that the mesh-generating points can in principle be moved arbitrarily. If they are given the velocity of the local flow, an accurate Lagrangian formulation of continuum hydrodynamics is obtained that features a very low numerical diffusivity and is free of mesh distortion problems. If the points are kept fixed, the scheme is equivalent to a Eulerian code on a structured mesh. The new AREPO code appears especially well suited for problems such as gravitational fragmentation or compressible turbulence.
Radiative Transfer Simulations of Infrared Dark Clouds
Authors: Pavlyuchenkov Yaroslav , Wiebe Dmitry , Fateeva Anna , Vasyunina Tatiana
Published: April 2011

The determination of prestellar core structure is often based on observations of (sub)millimeter dust continuum. However, recently the Spitzer Space Telescope provided us with IR images of many objects not only in emission but also in absorption. We developed a technique to reconstruct the density and temperature distributions of protostellar objects based on radiation transfer (RT) simulations both in mm and IR wavelengths. Best-fit model parameters are obtained with the genetic algorithm. We apply the method to two cores of Infrared Dark Clouds and show that their observations are better reproduced by a model with an embedded heating source despite the lack of 70 μm emission in one of these cores. Thus, the starless nature of massive cores can only be established with the careful case-by-case RT modeling.
Metastability mechanisms in thin film transistors quantitatively resolved using post-stress relaxation of threshold voltage
Authors: Fomani Arash A. , Nathan Arokia
Published: April 2011

A new approach is presented to resolve bias-induced metastability mechanisms in hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs). The post stress relaxation of threshold voltage (VT) was employed to quantitatively distinguish between the charge trapping process in gate dielectric and defect state creation in active layer of transistor. The kinetics of the charge de-trapping from the SiN traps is analytically modeled and a Gaussian distribution of gap states is extracted for the SiN. Indeed, the relaxation in VT is in good agreement with the theory underlying the kinetics of charge de-trapping from gate dielectric. For the TFTs used in this work, the charge trapping in the SiN gate dielectric is shown to be the dominant metastability mechanism even at bias stress levels as low as 10 V.
One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics
Authors: Xiong Gang , Hu Zhimin , Li Hang , Zhao Yang , Shang Wanli , Zhu Tuo , Wei Minxi , Yang Guohong , Zhang Jiyan , Yang Jiamin
Published: April 2011

A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5–50 Å. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p–3d transition absorption of Fe plasma near 15.5Å in has been observed clearly.
Broadband gigahertz dynamics of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3-xPbTiO3 single crystal probed by Brillouin scattering
Authors: Kojima S. , Tsukada S. , Hidaka Y. , Bokov A. A. , Ye Z.-G.
Published: April 2011

The broadband gigahertz dynamics of a relaxor ferroelectric crystal 0.70Pb(Sc1/2Nb1/2)O3-0.30PbTiO3 with a composition close to the starting point of the morphotropic phase boundary is studied by Brillouin scattering. The significant anomaly of the longitudinal acoustic (LA) mode is observed in the vicinity of the Curie temperature, TC = 500 K. Upon cooling, it starts below the Burns temperature, TB = 670 K, due to the interaction between the LA mode and dynamic polar nanoregions (PNRs). The broad central peak (CP) clearly appears below TB, and its intensity becomes a maximum at TC. The relaxation time, τCP, determined from the CP width, shows the typical critical slowing down of the order-disorder phase transition in the vicinity of TC. The size of a dynamic PNR significantly increases below the intermediate temperature, T* = 562 K.
Thermoelectric measurements using different tips in atomic force microscopy
Authors: Kushvaha S. S. , Hofbauer W. , Loke Y. C. , Singh Samarendra P. , O’Shea S. J.
Published: April 2011

We use conducting atomic force microscopy (AFM) in ultra high vacuum to measure the thermoelectric power of Au, Pt, and 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) films. Tips coated with thick (1200 nm) Pt films or highly doped diamond film give reproducible data. The thermoelectric power of metal junctions formed with diamond tips is high but dominated by the diamond material thus making diamond tips of limited applicability in thermovoltage AFM. Pt coated tips on Au or Pt films gives small thermovoltage signal, making quantitative analysis of the thermopower on metal sample problematic. The thermovoltage AFM technique appears best suited to study organic thin films and the thermoelectric power of 1.5 nm and 2 nm thick PTCDA deposited on Au measured with Pt tips is −342 and −372 μV/K, respectively. The negative sign indicates that the lowest unoccupied molecular orbital level dominates electrical transport.
Reduction of temperature fluctuation within low temperature region using a cryocooler
Authors: Nakamura Daiki , Hasegawa Yasuhiro , Murata Masayuki , Yamamoto Hiroya , Tsunemi Fumiaki , Komine Takashi
Published: April 2011

Modeling and experiments are performed to decrease temperature fluctuation generated by the periodic motion of the displacer in a Gifford–McMahon (GM) type cryocooler within the low-temperature region. The one-dimensional heat equation allows us to show that thermal diffusivity is an essential factor to achieve much smaller temperature fluctuation, and fiber-reinforced plastic (FRP) with low thermal diffusivity makes it possible to reduce the temperature fluctuation dramatically. Based on the model, experiments are performed to vary the thickness of two FRP dampers, on the cryohead of the cryocooler and on the sample stage. As a result, the FRP dampers enable us to achieve the temperature fluctuations of only 0.7 mK, corresponding to a standard deviation of 0.25 mK, when the sample stage is maintained at 4.2000 K, even if a GM cryocooler is utilized for cooling the temperature, which introduces an initial temperature fluctuation of 282 mK at the cryohead.
In situ probing of helium desorption from individual nanobubbles under electron irradiation
Authors: David M.-L. , Pailloux F. , Mauchamp V. , Pizzagalli L.
Published: April 2011

The understanding of the mechanisms of helium bubble formation and evolution in materials requires the quantitative determination of several key quantities such as the helium density in the bubbles. Helium nanobubbles of about 16 nm in diameter were created in silicon by helium implantation at high fluence and subsequent annealing. Individual nanobubbles were analyzed by spatially resolved Electron Energy-loss Spectroscopy (EELS). We report on the in situ probing of helium desorption from the nanobubbles under electron irradiation. This opens new perspectives for a more accurate determination of the helium density through spatially resolved EELS.
In-line absorption sensor based on coiled optical microfiber
Authors: Lorenzi Roberto , Jung Yongmin , Brambilla Gilberto
Published: April 2011

We fabricated and tested an evanescent-wave absorption sensor consisting of an optical microfiber coil resonator embedded in fluidic channel walls. Low concentrations of flowing analyte show optical losses in agreement with a modified Beer–Lambert law. Higher concentration causes a limit value of the measured optical losses arising from adsorption mechanisms.
Ballistic thermoelectricity in double-bend nanowires
Authors: Zhou Jun , Yang Ronggui
Published: April 2011

We investigate ballistic thermoelectric transport in double-bend nanowires. The geometric confinement induces quantum interference effect, which results in large Seebeck coefficient. The Seebeck coefficient (both the sign and the amplitude) is tunable by changing the structural parameters of the double-bend nanowires. Geometry-controlled ballistic thermoelectric effect could potentially be explored to design thermoelectric devices such as thermocouples at nanoscale.
Atomistic approach to alloy scattering in Si1−xGex
Authors: Mehrotra Saumitra R. , Paul Abhijeet , Klimeck Gerhard
Published: April 2011

SiGe alloy scattering is of significant importance with the introduction of strained layers and SiGe channels into complementary metal-oxide semiconductor technology. However, alloy scattering has till now been treated in an empirical fashion with a fitting parameter. We present a theoretical model within the atomistic tight-binding representation for treating alloy scattering in SiGe. This approach puts the scattering model on a solid atomistic footing with physical insights. The approach is shown to inherently capture the bulk alloy scattering potential parameters for both n-type and p-type carriers and matches experimental mobility data.
Tour of bordered Floer theory
Authors: Lipshitz Robert , Ozsváth Peter S. , Thurston Dylan P.
Published: April 2011

Heegaard Floer theory is a kind of topological quantum field theory (TQFT), assigning graded groups to closed, connected, oriented 3-manifolds and group homomorphisms to smooth, oriented four-dimensional cobordisms. Bordered Heegaard Floer homology is an extension of Heegaard Floer homology to 3-manifolds with boundary, with extended-TQFT-type gluing properties. In this survey, we explain the formal structure and construction of bordered Floer homology and sketch how it can be used to compute some aspects of Heegaard Floer theory.
Selective activation of the transcription factor ATF6 mediates endoplasmic reticulum proliferation triggered by a membrane protein
Authors: Maiuolo Jessica , Bulotta Stefania , Verderio Claudia , Benfante Roberta , Borgese Nica
Published: April 2011

It is well known that the endoplasmic reticulum (ER) is capable of expanding its surface area in response both to cargo load and to increased expression of resident membrane proteins. Although the response to increased cargo load, known as the unfolded protein response (UPR), is well characterized, the mechanism of the response to membrane protein load has been unclear. As a model system to investigate this phenomenon, we have used a HeLa-TetOff cell line inducibly expressing a tail-anchored construct consisting of an N-terminal cytosolic GFP moiety anchored to the ER membrane by the tail of cytochrome b5 [GFP-b(5)tail]. After removal of doxycycline, GFP-b(5)tail is expressed at moderate levels (1–2% of total ER protein) that, nevertheless, induce ER proliferation, as assessed both by EM and by a three- to fourfold increase in phosphatidylcholine synthesis. We investigated possible participation of each of the three arms of the UPR and found that only the activating transcription factor 6 (ATF6) arm was selectively activated after induction of GFP-b(5)tail expression; peak ATF6α activation preceded the increase in phosphatidylcholine synthesis. Surprisingly, up-regulation of known ATF6 target genes was not observed under these conditions. Silencing of ATF6α abolished the ER proliferation response, whereas knockdown of Ire1 was without effect. Because GFP-b(5)tail lacks a luminal domain, the response we observe is unlikely to originate from the ER lumen. Instead, we propose that a sensing mechanism operates within the lipid bilayer to trigger the selective activation of ATF6.