bluuebunny/crossref_metadata_2025 huggingface dataset:
Method to increase the yield of eukaryotic membrane protein expression in Saccharomyces cerevisiae for structural and functional studies
Authors: Parker Joanne L. , Newstead Simon
Published: June 2014

Despite recent successes in the structure determination of eukaryotic membrane proteins, the total number of structures of these important proteins is severely underrepresented in the Protein Data Bank. Although prokaryotic homologues provide valuable mechanistic insight, they often lack crucial details, such as post‐translational modification and additional intra or extracellular domains that are important for understanding the function and regulation of these proteins in eukaryotic cells. The production of milligram quantities of recombinant protein is still a serious obstacle to the structural and functional characterization of these proteins. Here, we report a modification to a previously described over expression system using the simple eukaryote Saccharomyces cerevisiae that can increase overall protein yield and improve downstream purification procedures. Using a metabolic marker under the control of a truncated promoter, we show that expression levels for several membrane transporters are increased fourfold. We further demonstrate that the increase in expression for our test proteins resulted in a concomitant increase in functional protein. Using this system, we were able to increase the expression level of a plant transporter, NRT1.1, which was a key factor in its structural and functional characterization.
Intracellular selection of peptide inhibitors that target disulphide‐bridged Aβ42 oligomers
Authors: Acerra Nicola , Kad Neil. M. , Cheruvara Harish , Mason Jody M.
Published: June 2014

The β‐amyloid (Aβ) peptide aggregates into a number of soluble and insoluble forms, with soluble oligomers thought to be the primary factor implicated in Alzheimer's disease pathology. As a result, a wide range of potential aggregation inhibitors have been developed. However, in addition to problems with solubility and protease susceptibility, many have inadvertently raised the concentration of these soluble neurotoxic species. Sandberg et al. previously reported a β‐hairpin stabilized variant of Aβ42 that results from an intramolecular disulphide bridge (A21C/A31C; Aβ42cc), which generates highly toxic oligomeric species incapable of converting into mature fibrils. Using an intracellular protein‐fragment complementation (PCA) approach, we have screened peptide libraries using E. coli that harbor an oxidizing environment to permit cytoplasmic disulphide bond formation. Peptides designed to target either the first or second β‐strand have been demonstrated to bind to Aβ42cc, lower amyloid cytotoxicity, and confer bacterial cell survival. Peptides have consequently been tested using wild‐type Aβ42 via ThT binding assays, circular dichroism, MTT cytotoxicity assays, fluorescence microscopy, and atomic force microscopy. Results demonstrate that amyloid‐PCA selected peptides function by both removing amyloid oligomers as well as inhibiting their formation. These data further support the use of semirational design combined with intracellular PCA methodology to develop Aβ antagonists as candidates for modification into drugs capable of slowing or even preventing the onset of AD.
Increasing the Sensitivity of Cumulative Sum Charts for Location
Authors: Abujiya Mu'azu Ramat , Lee Muhammad Hisyam , Riaz Muhammad
Published: June 2014

The cumulative sum (CUSUM) chart is a very effective control charting procedure used for the quick detection of small‐sized and moderate‐sized changes. It can detect small process shifts missed by the Shewhart‐type control chart, which is sensitive mainly to large shifts. To further enhance the sensitivity of the CUSUM control chart at detecting very small process disturbances, this article presents CUSUM control charts based on well‐structured sampling procedures, double ranked set sampling, median‐double ranked set sampling, and double‐median ranked set sampling. These sampling techniques significantly improve the overall performance of the CUSUM chart over the entire process mean shift range, without increasing the false alarm rate. The newly developed control schemes do not only dominate most of the existing charts but are also easy to design and implement as illustrated through an application example of real datasets. The control schemes used for comparison in this study include the conventional CUSUM chart, a fast initial response CUSUM chart, a 2‐CUSUM chart, a 3‐CUSUM chart, a runs rules‐based CUSUM chart, the enhanced adaptive CUSUM chart, the CUSUM chart based on ranked set sampling (RSS), and the single CUSUM and combined Shewhart–CUSUM charts based on median RSS. Copyright © 2014 John Wiley & Sons, Ltd.
A Method for Supporting the Domain Expert by the Interpretation of Different Decision Trees Learnt from the Same Domain
Authors: Perner Petra
Published: June 2014

Data mining methods are widely used across many disciplines to identify patterns, rules, or associations among huge volumes of data. Data mining methods with explanation capability such as decision tree induction are preferred in many domains. The aim of this paper is to discuss how to deal with the result of decision tree induction methods. This paper has been prompted by the fact that domain experts are able to use the tools for decision tree induction but have great difficulties in interpreting the results. When the domain expert has learnt two decision trees that are from the same domain but based on different data sets as a result of further data collection, he is faced with the problem of how to interpret the different trees. The comparison of two decision trees is therefore an important issue as the user needs such a comparison in order to understand what has changed. We have proposed to provide him with a measure of correspondence between the two trees that allows him to judge if he can accept the changes or not. In this paper, we propose a proper similarity measure. In case of a low similarity value, the expert has evidence to start exploring the reason for this change. Often, he can find things in the data acquisition that might have resulted in some noise and might be fixed. Copyright © 2014 John Wiley & Sons, Ltd.
Modifications to a commercially available linear mass spectrometer for mass‐resolved microscopy with the pixel imaging mass spectrometry (PImMS) camera
Authors: Halford E. , Winter B. , Mills M. D. , Thompson S. P. , Parr V. , John J. J. , Nomerotski A. , Vallance C. , Turchetta R. , Brouard M.
Published: June 2014

RATIONALE

Imaging mass spectrometry is a powerful analytical technique capable of accessing a large volume of spatially resolved, chemical data from two‐dimensional samples. Probing the entire surface of a sample simultaneously requires a detector with high spatial and temporal resolutions, and the ability to observe events relating to different mass‐to‐charge ratios.

METHODS

A commercially available time‐of‐flight mass spectrometer, designed for matrix‐assisted laser desorption/ionization (MALDI) analysis, was combined with the novel pixel imaging mass spectrometry (PImMS) camera in order to perform multi‐mass, microscope‐mode imaging experiments. A number of minor modifications were made to the spectrometer hardware and ion optics so that spatial imaging was achieved for a number of small molecules.

RESULTS

It was shown that a peak width of Δm50 % <  1  m/z unit across the range 200 ≤ m/z  ≤  800 can be obtained while also achieving an optimum spatial resolution of 25 µm. It was further shown that these data were obtained simultaneously for all analytes present without the need to scan the experimental parameters.

CONCLUSIONS

This work demonstrates the capability of multi‐mass, microscope‐mode imaging to reduce the acquisition time of spatially distributed analytes such as multi‐arrays or biological tissue sections. It also shows that such an instrument can be commissioned by effecting relatively minor modifications to a conventional commercial machine. Copyright © 2014 John Wiley & Sons, Ltd.
A novel asymmetrical arc‐shaped electrode ion trap for improving the performance of a miniature mass spectrometer
Authors: Zhang Zhong‐yao , Li Cuiping , Ding Chuan‐fan , Xu Fuxing , Li Baoqiang , Huang Qibin , Xia Hengxin
Published: June 2014

RATIONALE

The pivotal challenge associated with miniature mass analyzers is their proper design and construction without sacrificing performance. In order to analyze and improve the performance of a miniature linear ion trap with odd and even multipole fields, we designed a novel asymmetrical arc‐shaped electrode ion trap (AAEIT), and tested the properties of AAEITs with different dimensions.

METHODS

A series of asymmetrical ion traps using arc‐shaped electrodes were designed to optimize the properties (resolutions and intensity) of the coupling effects between odd and even multipole fields. Using arginine and reserpine, we evaluated the performance of mass resolution, ion intensity ratio and deduced the collision‐induced dissociation (CID) efficiency using a self‐constructed electrospray ionization mass spectrometry (ESI‐MS) platform.

RESULTS

An AAEIT with field radius dimensions of 5 mm × 5.75 mm exhibits a good performance: its maximum resolution of 833 (FWHM) at m/z 175 was achieved for the side of small electrode. With this AAEIT, a tandem mass (MS/MS) capability with 91.0% CID efficiency was obtained with reserpine (m/z 609).

CONCLUSIONS

The results indicated that the AAEIT, comprising both odd and even multipole fields, could act as a qualified linear ion trap mass analyzer with compact structure, high resolution, and high tandem mass analysis efficiency. It has a great potential in miniature mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.
Contribution of thermal energy to initial ion production in matrix‐assisted laser desorption/ionization observed with 2,4,6‐trihydroxyacetophenone
Authors: Lai Yin‐Hung , Chen Bo‐Gaun , Lee Yuan Tseh , Wang Yi‐Sheng , Lin Sheng Hsien
Published: June 2014

RATIONALE

Although several reaction models have been proposed in the literature to explain matrix‐assisted laser desorption/ionization (MALDI), further study is still necessary to explore the important ionization pathways that occur under the high‐temperature environment of MALDI. 2,4,6‐Trihydroxyacetophenone (THAP) is an ideal compound for evaluating the contribution of thermal energy to an initial reaction with minimum side reactions.

METHODS

Desorbed neutral THAP and ions were measured using a crossed‐molecular beam machine and commercial MALDI‐TOF instrument, respectively. A quantitative model incorporating an Arrhenius‐type desorption rate derived from transition state theory was proposed. Reaction enthalpy was calculated using GAUSSIAN 03 software with dielectric effect. Additional evidence of thermal‐induced proton disproportionation was given by the indirect ionization of THAP embedded in excess fullerene molecules excited by a 450 nm laser.

RESULTS

The quantitative model predicted that proton disproportionation of THAP would be achieved by thermal energy converted from a commonly used single UV laser photon. The dielectric effect reduced the reaction Gibbs free energy considerably even when the dielectric constant was reduced under high‐temperature MALDI conditions. With minimum fitting parameters, observations of pure THAP and THAP mixed with fullerene both agreed with predictions.

CONCLUSIONS

Proton disproportionation of solid THAP was energetically favorable with a single UV laser photon. The quantitative model revealed an important initial ionization pathway induced by the abrupt heating of matrix crystals. In the matrix crystals, the dielectric effect reduced reaction Gibbs free energy under typical MALDI conditions. The result suggested that thermal energy plays an important role in the initial ionization reaction of THAP. Copyright © 2014 John Wiley & Sons, Ltd.
Microfluidic Molding of Photonic Microparticles with Engraved Elastomeric Membranes
Authors: Sim Jae Young , Choi Jae‐Hoon , Lim Jong‐Min , Cho Soojeong , Kim Shin‐Hyun , Yang Seung‐Man
Published: June 2014

A microfluidic approach to prepare photonic microparticles by repeated molding of photocurable colloidal suspension is reported. An elastomeric membrane with negative relieves which vertically separates two microfluidic channels is integrated; bottom channel is used for suspension flow, whereas water‐filled top channel is used for pneumatic actuation of the membrane. Upon pressurization of the top channel, membrane is deformed to confine the suspension into its negative relieves, which is then polymerized by UV irradiation, making microparticles with mold shape. The microparticles are released from the mold by relieving the pneumatic pressure and flows through the bottom channel. This one cycle of molding, polymerization, and release can be repeatedly performed in microfluidic device of which pneumatic valves are actuated in a programmed manner. The microparticles exhibit structural colors when the suspension contains high concentration of silica nanoparticles; the nanoparticles form regular arrays and the microparticles reflect specific wavelength of light as a photonic crystals. The silica nanoparticles can be selectively removed to make pronounced structural colors. In addition, the microparticles can be further functionalized by embedding magnetic particles in the matrix of the microparticles, enabling the remote control of rotational motion of microparticles.
Inhibition of 3‐D Tumor Spheroids by Timed‐Released Hydrophilic and Hydrophobic Drugs from Multilayered Polymeric Microparticles
Authors: Lee Wei Li , Guo Wei Mei , Ho Vincent H. B. , Saha Amitaksha , Chong Han Chung , Tan Nguan Soon , Widjaja Effendi , Tan Ern Yu , Loo Say Chye Joachim
Published: June 2014

First‐line cancer chemotherapy necessitates high parenteral dosage and repeated dosing of a combination of drugs over a prolonged period. Current commercially available chemotherapeutic agents, such as Doxil and Taxol, are only capable of delivering single drug in a bolus dose. The aim of this study is to develop dual‐drug‐loaded, multilayered microparticles and to investigate their antitumor efficacy compared with single‐drug‐loaded particles. Results show hydrophilic doxorubicin HCl (DOX) and hydrophobic paclitaxel (PTX) localized in the poly(dl‐lactic‐co‐glycolic acid, 50:50) (PLGA) shell and in the poly(l‐lactic acid) (PLLA) core, respectively. The introduction of poly[(1,6‐bis‐carboxyphenoxy) hexane] (PCPH) into PLGA/PLLA microparticles causes PTX to be localized in the PLLA and PCPH mid‐layers, whereas DOX is found in both the PLGA shell and core. PLGA/PLLA/PCPH microparticles with denser shells allow better control of DOX release. A delayed release of PTX is observed with the addition of PCPH. Three‐dimensional MCF‐7 spheroid studies demonstrate that controlled co‐delivery of DOX and PTX from multilayered microparticles produces a greater reduction in spheroid growth rate compared with single‐drug‐loaded particles. This study provides mechanistic insights into how distinctive structure of multilayered microparticles can be designed to modulate the release profiles of anticancer drugs, and how co‐delivery can potentially provide better antitumor response.
Restructuring and Remodeling of NaREF4 Nanocrystals by Electron Irradiation
Authors: Sun Xiaoyu , Wang Bingru , Kempson Ivan , Liu Chunyan , Hou Yi , Gao Mingyuan
Published: June 2014

NaREF4 nanocrystals are found to be highly manipulable by electron beam irradiation. With 200 kV electron beam irradiation, both 14.6 nm spherical NaGdF4:Yb,Er nanoparticles and 44.7 nm × 34.1 nm ellipsoidal NaYF4:Yb,Er nanorods form hollow structures and eventually convert to the corresponding REF3 upon prolonged irradiation. Furthermore, the NaYF4 nanorods fractured with irradiation with a 100 kV electron source are found to be subsequently self‐healed when irradiated with a 200 kV source. The detailed experimental results, in combination with theoretical analysis, suggest that knock‐on effects, specific lattice energy, and the inherently low surface energy of NaREF4 collectively contribute to the formation of the hollow structures. These mechanisms allow controlled engineering and manipulation of RE nanomaterials on the nanometer scale.
Novel design for non‐latency wireless binaural hearing aids
Authors: Wei Qun , Park Young Sik , Lee Seul Bi , Kim Dong Wook , Seong Ki Woong , Lee Jyung Hyun , Lee Seung‐Ha , Cho Jin‐Ho
Published: June 2014

Binaural hearing aids consist of two hearing devices, one for each ear. A new concept of binaural hearing aids is proposed, in which only the master hearing aid contains a Bluetooth chip for receiving stereo audio signals from an external device, and the signal in one channel is sent to the slave hearing aid from the master by a 2.4‐GHz Gaussian frequency‐shift keying (GFSK) RF transmission method to create the binaural hearing effect. However, a problem arises in regard to the processing necessary for the signal transmission and reception in the two hearing aids, which creates a time delay that causes the precedence effect. Therefore, an audio delay processing algorithm has been designed in the master hearing aid to synchronize with the sound output of the slave hearing aid. Experimental results show that the time difference between the two hearing aids is about 8 µs, which is effective for avoiding the precedence effect. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Why the Monte Carlo method is so important today
Authors: Kroese Dirk P. , Brereton Tim , Taimre Thomas , Botev Zdravko I.
Published: June 2014

Since the beginning of electronic computing, people have been interested in carrying out random experiments on a computer. Such Monte Carlo techniques are now an essential ingredient in many quantitative investigations. Why is the Monte Carlo method (MCM) so important today? This article explores the reasons why the MCM has evolved from a ‘last resort’ solution to a leading methodology that permeates much of contemporary science, finance, and engineering. WIREs Comput Stat 2014, 6:386–392. doi: 10.1002/wics.1314

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Markov Chain Monte Carlo (MCMC)

Statistical Models > Simulation Models
Preoperative Biliary Drainage of Severely Jaundiced Patients Increases Morbidity of Pancreaticoduodenectomy: Results of a Case‐Control Study
Authors: Arkadopoulos Nikolaos , Kyriazi Maria A. , Papanikolaou Ioannis S. , Vasiliou Pantelis , Theodoraki Kassiani , Lappas Christos , Oikonomopoulos Nikolaos , Smyrniotis Vassilios
Published: June 2014

Background

Recent studies have indicated that preoperative biliary drainage (PBD) should not be routinely performed in patients suffering from obstructive jaundice before surgery. The severity of jaundice that mandates PBD has yet to be defined. Our aim was to investigate whether PBD is truly justified in severely jaundiced patients before pancreaticoduodenectomy. The parameters evaluated were overall morbidity, length of hospital stay, and total in‐hospital mortality.

Methods

From January 2000 to December 2012, a total of 240 patients underwent pancreaticoduodenectomy for periampullary tumors. Group A comprised 76 patients with preoperative serum bilirubin ≥15 mg/dl who did not undergo PBD before surgery. Group B comprised another 76 patients, matched for age and tumor localization (papillary vs. pancreatic head) who underwent PBD 2–4 weeks before pancreaticoduodenectomy and were identified from the same database.

Results

Less operative time was required in the ‘no PBD’ group compared with the ‘PBD’ group (210 vs. 240 min). Total intraoperative blood loss and blood transfusions were also significantly less in the ‘no PBD’ group. There was no difference detected in the rate of pancreatic fistula or biliary fistula formation. Group A patients demonstrated significantly lower morbidity than group B (24 vs. 36 %, respectively) and therefore required briefer hospitalization (11 vs. 16 days). Mild infectious complications appear to be the main factor that enhanced morbidity in the PBD group. However, total in‐hospital mortality was not significantly different between the two groups.

Conclusions

Even severe jaundice should not be considered as an indication for PBD before pancreaticoduodenectomy, as PBD increases infections and postoperative morbidity, therefore delaying definite treatment.
Feasibility of a Community Intervention for the Prevention of Suicide and Alcohol Abuse with Yup'ik Alaska Native Youth: The Elluam Tungiinun and Yupiucimta Asvairtuumallerkaa Studies
Authors: Mohatt Gerald V. , Fok Carlotta Ching Ting , Henry David , Allen James
Published: June 2014

The Elluam Tungiinun and Yupiucimta Asvairtuumallerkaa studies evaluated the feasibility of a community intervention to prevent suicide and alcohol abuse among rural Yup'ik Alaska Native youth in two remote communities. The intervention originated in an Indigenous model of protection, and its development used a community based participatory research process. Feasibility assessment aimed to assess the extent to which (1) the intervention could be implemented in rural Alaska Native communities, and (2) the intervention was capable of producing measurable effects. Scales maximally sensitive to change were derived from earlier measurement work, and the study contrasted implementation process and outcomes across the two communities. In one community, medium dose response effects (d = .30–.50), with dose defined as number of intervention activities attended, were observed in the growth of intermediate protective factors and ultimate variables. In the other community, medium dose effects were observed for one intermediate protective factor variable, and small dose effects were observed in ultimate variables. Differences across communities in resources supporting intervention explain these contrasting outcomes. Results suggest implementation in these rural Alaska settings is feasible when sufficient resources are available to sustain high levels of local commitment. In such cases, measureable effects are sufficient to warrant a prevention trial.
Neurotrophins: Role in adverse pregnancy outcome
Authors: Dhobale Madhavi
Published: June 2014

Proper placental development is essential during pregnancy since it forms the interface between the maternal–foetal circulations and is critical for foetal nutrition and oxygenation. Neurotrophins such as nerve growth factor (NGF), brain derived neurotrophin (BDNF), neurotrophin‐3 (NT‐3) and neurotrophin‐4/5 (NT‐4/5) are naturally occurring molecules that regulate development of the placenta and brain. BDNF and NGF also involved in the regulation of angiogenesis. Recent studies suggest that the levels of BDNF and NGF are regulated by docosahexaenoic acid (DHA) which is an important omega‐3 fatty acid and is a structural component of the plasma membrane. Oxidative stress during pregnancy may lower the levels of DHA and affecting the fluidity of the membranes leading to the changes in the levels and expression of BDNF and NGF. Therefore altered levels and expression of NGF and BDNF may lead to abnormal foetal growth and brain development that may increase the risk for cardiovascular disease, metabolic syndromes and neurodevelopmental disorders in children born preterm. This review discuss about the neurotrophins and their role in the feto‐placental unit during critical period of pregnancy.
Quadratic stochastic operators and zero-sum game dynamics
Authors: GANIKHODJAEV NASIR N. , GANIKHODJAEV RASUL N. , JAMILOV U. U.
Published: June 2014

In this paper we consider the set of all extremal Volterra quadratic stochastic operators defined on a unit simplex $S^{4}$ and show that such operators can be reinterpreted in terms of zero-sum games. We show that an extremal Volterra operator is non-ergodic and an appropriate zero-sum game is a rock-paper-scissors game if either the Volterra operator is a uniform operator or for a non-uniform Volterra operator $V$ there exists a subset $I\subset \{1,2,3,4,5\}$ with $|I|\leq 2$ such that $\sum _{i\in I}(V^{n}\mathbf{x})_{i}\rightarrow 0,$ and the restriction of $V$ on an invariant face ${\rm\Gamma}_{I}=\{\mathbf{x}\in S^{m-1}:x_{i}=0,i\in I\}$ is a uniform Volterra operator.
Long-wave dynamics of an inextensible planar membrane in an electric field
Authors: Young Y.-N. , Veerapaneni Shravan , Miksis Michael J.
Published: June 2014

In this paper the dynamics of an inextensible capacitive elastic membrane under an electric field is investigated in the long-wave (lubrication) leaky dielectric framework, where a sixth-order nonlinear differential equation with an integral constraint is derived. Steady equilibrium profiles for a non-conducting membrane in a direct current (DC) field are found to depend only on the membrane excess area and the volume under the membrane. Linear stability analysis on a tensionless flat membrane in a DC field gives the growth rate in terms of membrane conductance and electric properties in the bulk. Numerical simulations of a capacitive conducting membrane under an alternating current (AC) field elucidate how variation of the membrane tension correlates with the nonlinear membrane dynamics. Different membrane dynamics, such as undulation and flip-flop, are found at different electric field strength and membrane area. In particular a travelling wave on the membrane is found as a response to a periodic AC field in the perpendicular direction.
Contested Colonialism: Responsible Government and Political Development in Yukon
Authors: Sabin Jerald
Published: June 2014

This article argues that the granting of responsible government to Yukon in 1979 was not the inevitable outcome of territorial political development but the result of a protracted and organized settler political movement that emerged first in opposition to the federal government and, later, to Yukon's Indigenous peoples. I analyze settler actor political behaviour and outcomes using the framework of “contested colonialism.” Non-Indigenous Yukoners are understood as actors who simultaneously bring colonialism to the North while also contesting elements of that same colonial order. Using extensive archival research, I identify several critical junctures leading to the implementation of responsible government during the 1960s and 1970s.
SHORT- TO MID-TERM IMPACT OF CONSERVATION AGRICULTURE ON YIELD VARIABILITY OF UPLAND RICE: EVIDENCE FROM FARMER’S FIELDS IN MADAGASCAR
Authors: BRUELLE GUILLAUME , NAUDIN KRISHNA , SCOPEL ERIC , DOMAS RAPHAËL , RABEHARISOA LILIA , TITTONELL PABLO
Published: June 2014

Family farming in the tropics suffers from low crop productivity mainly due to a combination of poor soil fertility, low investment capacity, and a variable climate. The Lake Alaotra region of Madagascar is no exception and rainfed production is particularly hard hit. To evaluate the agronomic benefits of conservation agriculture (CA) in a region of erratic rainfall, we analysed four years of yield, management and climatic data from 3803 upland rice fields cultivated by farmers and monitored by researchers. Fields located on rainfed lowlands and hillsides were cultivated with sole rice using conventional tillage (Cv) or rice sown with no-tillage on dead organic mulch and rotated with other cereal/legume combinations (CA) from 2006 to 2011. A first global comparison across seasons, locations and years of adoption showed significantly higher average yields under CA, with no change in variance (on lowland: 2.6 ± 0.9 t ha–1 Cv, 2.8 ± 0.9 t ha–1 CA; on hillside: 2.1 ± 0.8 t ha–1 Cv, 2.4 ± 0.8 t ha–1 CA). Grouping fields according to the number of years under CA (first to fourth) revealed that CA gradually increased average yields and reduced the coefficient of variation in the short and mid-term (on lowland: +0.2 t ha–1 and –6% coefficient of variation; on hillside: +0.7 t ha–1 and –13% coefficient of variation, over four to six years of successive CA cropping). The average yield increase under CA was not associated with an increase in mineral fertiliser use, as farmers used the same amounts of fertilisers (or none) under Cv and CA. The comparison Cv versus CA also highlighted a major benefit of CA regarding climate: it widened the window of possible sowing dates. A classification and regression tree analysis of the entire dataset revealed that rice yield was more affected by agro-environmental factors than management factors (fertilisation, Cv or CA), and extreme climate variability such as the severe drought of 2007–2008 could not be offset by CA. The hypothesis of yield penalties during the first years of implementation of CA cannot be verified with the evidence presented in this study.
Diet and feeding strategy of thornback ray,Raja clavata(Chondrichthyes: Rajidae) from the Gulf of Gabes (Tunisia—Central Mediterranean Sea)
Authors: Kadri Hasna , Marouani Sondes , Bradai Mohamed Nejmeddine , Bouaïn Abderrahmen
Published: June 2014

Food and feeding strategy of the thornback ray,Raja clavata, were studied from stomach contents analysis of specimens caught monthly in the Gulf of Gabes. The data were analysed according to sex, size and season. At total of 1280 stomachs was examined, from specimens ranging from 14 to 110 cm total length (TL), of which 1076 (83.98%) contained food. Thornback ray feed mainly on teleosts, crustaceans and cephalopods, whereas gastropods and polychaetes are occasionally consumed. Significant differences were found between the diets of males and females; however, ontogenetic changes were also detected, with crustaceans constituting the greatest proportion of the diet of smaller rays. Both teleosts and cephalopods increased in importance with growth of the skates. Prey diversity increased with size; large and mobile prey species were more commonly found in the diet of larger skates. Diet composition showed seasonal variations. Quantitative analyses and graphical methods indicate that the thornback ray is a generalist feeder.
Higher population densities of the sea urchinDiadema antillarumlinked to wave sheltered areas in north Puerto Rico Archipelago
Authors: Rodríguez-Barreras Ruber , Pérez María E. , Mercado-Molina Alex E. , Williams Stacey M. , Sabat Alberto M.
Published: June 2014

The long-spined sea urchinDiadema antillarumhas been the focus of multiple studies since the mass mortality event in the 1980s. The recovery of this key herbivore in the wider Caribbean is essential for the well-being of coral reefs. This study examined the population density and structure ofD. antillarumat seven northern fringing reefs of Puerto Rico between 2011 and 2013. The total mean density of the sea urchins in northern Puerto Rico was 0.9 ±0.3 ind m−2. Densities ofD. antillarumsignificantly differed among sites, but not temporally. Differences in mean sizes were significant among sites and seasons. Areas with higher densities ofD. antillarumshowed lower cover of non-calcareous algae. Wave exposure was correlated with the abundance of the sea urchin. This study indicates that the observed abundance ofD. antillarumhas not yet returned to pre-mortality levels. However, densities showed some degree of recovery when compared with previous studies, enabling at least some degree of control on fleshy macroalgae communities. No significant changes in density occurred between 2011 and 2013, and sites with higher densities were generally located in leeward areas. The low relative abundance of small size individuals points towards recruitment limitation as an explanation for the limited recovery ofD. antillarum.
Mental health in Dutch adolescents: a TRAILS report on prevalence, severity, age of onset, continuity and co-morbidity of DSM disorders
Authors: Ormel J. , Raven D. , van Oort F. , Hartman C. A. , Reijneveld S. A. , Veenstra R. , Vollebergh W. A. M. , Buitelaar J. , Verhulst F. C. , Oldehinkel A. J.
Published: June 2014

Background

With psychopathology rising during adolescence and evidence suggesting that adult mental health burden is often due to disorders beginning in youth, it is important to investigate the epidemiology of adolescent mental disorders.

Method

We analysed data gathered at ages 11 (baseline) and 19 years from the population-based Dutch TRacking Adolescents' Individual Lives Survey (TRAILS) study. At baseline we administered the Achenbach measures (Child Behavior Checklist, Youth Self-Report) and at age 19 years the World Health Organization's Composite International Diagnostic Interview version 3.0 (CIDI 3.0) to 1584 youths.

Results

Lifetime, 12-month and 30-day prevalences of any CIDI-DSM-IV disorder were 45, 31 and 15%, respectively. Half were severe. Anxiety disorders were the most common but the least severe whereas mood and behaviour disorders were less prevalent but more severe. Disorders persisted, mostly by recurrence in mood disorders and chronicity in anxiety disorders. Median onset age varied substantially across disorders. Having one disorder increased subjects' risk of developing another disorder. We found substantial homotypic and heterotypic continuity. Baseline problems predicted the development of diagnosable disorders in adolescence. Non-intact families and low maternal education predicted externalizing disorders. Most morbidity concentrated in 5–10% of the sample, experiencing 34–55% of all severe lifetime disorders.

Conclusions

At late adolescence, 22% of youths have experienced a severe episode and 23% only mild episodes. This psychopathology is rather persistent, mostly due to recurrence, showing both monotypic and heterotypic continuity, with family context affecting particularly externalizing disorders. High problem levels at age 11 years are modest precursors of incident adolescent disorders. The burden of mental illness concentrates in 5–10% of the adolescent population.
The effects on biomechanics of walking and balance recovery in a novel pelvis exoskeleton during zero-torque control
Authors: Martelli Dario , Vannetti Federica , Cortese Mario , Tropea Peppino , Giovacchini Francesco , Micera Silvestro , Monaco Vito , Vitiello Nicola
Published: June 2014

Fall-related accidents are among the most serious concerns in elderly people, amputees and subjects with neurological disorders. The aim of this paper was to investigate the behaviour of healthy subjects wearing a novel light-weight pelvis exoskeleton controlled in zero-torque mode while carrying out unperturbed locomotion and managing unexpected perturbations. Results showed that the proposed exoskeleton was unobtrusive and had a minimum loading effect on the human biomechanics during unperturbed locomotion. Conversely, it affected the movement of the trailing leg while subjects managed unexpected slipping-like perturbations. These findings support further investigations on the potential use of powered exoskeletons to assist locomotion and, possibly prevent incipient falls.
Tree damage and microclimate of forest canopies along a hurricane-impact gradient in Cusuco National Park, Honduras
Authors: Batke Sven Peter , Kelly Daniel Lucius
Published: June 2014

Past studies of large, infrequent wind disturbances have shown that topographical, biological and meteorological factors interact to create complex damage patterns to forest ecosystems. However, the extent to which some of these factors change the forest microclimate along a vertical forest profile is poorly known. In a previous study, we correlated tree damage with a hurricane model that estimated past hurricane impacts within Cusuco National Park, Honduras over a 15-y period. Here we use the model to compare physical tree damage among different species in ten 150 ×150-m plots and to correlate modelled exposure of hurricanes to microclimate measurements along the vertical canopy over a 12-mo period. It was found that past hurricane impacts could still be detected long after the events. Different tree species showed different levels of wind damage. Most branch damage was observed on conifers (Pinusspp.), followed by angiosperm species. Vapour pressure deficit increased with height in the canopy and with increased disturbance level. A linear model explained 83% of the total variance in vapour pressure deficit, with 67% attributed to monthly fluctuation, 15% to altitude, 12% to historical hurricane damage and 6% to height in the canopy.
Using population dynamics modelling to evaluate potential success of restoration: a case study of a Hawaiian vine in a changing climate
Authors: WONG TAMARA M. , TICKTIN TAMARA
Published: June 2014

Demographic comparisons between wild and restored populations of at-risk plant species can reveal key management strategies for effective conservation, but few such studies exist. This paper evaluates the potential restoration success ofAlyxia stellata, a Hawaiian vine. Stage-structured matrix projection models that compared long-term and transient dynamics of wild versus restoredA. stellatapopulations, and restored populations under different levels of canopy cover, were built from demographic data collected over a four year period. Stochastic models of wild populations projected stable or slightly declining long-term growth rates depending on frequency of dry years. Projected long-term population growth rates of restored populations were significantly higher in closed than open canopy conditions, but indicated population decline under both conditions. Life table response experiments illustrated that lower survival rates, especially of small adults and juveniles, contributed to diminished population growth rates in restored populations. Transient analyses for restored populations projected short-term decline occurring even faster than predicted by asymptotic dynamics. Restored populations will not be viable over the long term under conditions commonly found in restoration projects and interventions will likely be necessary. This study illustrates how the combination of long-term population modelling and transient analyses can be effective in providing relevant information for plant demographers and restoration practitioners to promote self-sustaining native populations, including under future climates.
Visualization of Hierarchical Nanodomains in Polymer/Fullerene Bulk Heterojunction Solar Cells
Authors: Wen Jianguo , Miller Dean J. , Chen Wei , Xu Tao , Yu Luping , Darling Seth B. , Zaluzec Nestor J.
Published: June 2014

Traditional electron microscopy techniques such as bright-field imaging provide poor contrast for organic films and identification of structures in amorphous material can be problematic, particularly in high-performance organic solar cells. By combining energy-filtered corrected transmission electron microscopy, together with electron energy loss and X-ray energy-dispersive hyperspectral imaging, we have imaged PTB7/PC61BM blended polymer optical photovoltaic films, and were able to identify domains ranging in size from several hundred nanometers to several nanometers in extent. This work verifies that microstructural domains exist in bulk heterojunctions in PTB7/PC61BM polymeric solar cells at multiple length scales and expands our understanding of optimal device performance providing insight for the design of even higher performance cells.
Propagation and energy deposition of cosmic rays’ muons on terrestrial environments
Authors: Marinho Franciole , Paulucci Laura , Galante Douglas
Published: June 2014

The Earth is constantly struck by radiation coming from the interstellar medium. The very low energy end of the spectrum is shielded by the geomagnetic field but charged particles with energies higher than the geomagnetic cutoff will penetrate the atmosphere and are likely to interact, giving rise to secondary particles. Some astrophysical events, such as γ-ray bursts and supernovae, when happening at short distances, may affect the planet's biosphere, due to the temporary enhanced radiation flux. Muons are abundantly produced by high-energy cosmic rays in the Earth's atmosphere. These particles, due to their low cross-section, are able to penetrate deep both underground and underwater, with the possibility of affecting biological niches normally considered shielded from radiation. We investigate the interaction of muons produced by high-energy cosmic rays on the Earth's atmosphere using the Geant4 toolkit. We analyse its penetration power in water and crust and also the interaction effects within bacteria-like material according to the particle type and energy, and noticed the possibility of off-track damage due to secondary particles.
Disarming norms: postcolonial agency and the constitution of the international
Authors: Jabri Vivienne
Published: June 2014

The aim of this article is to provide a postcolonial reading of norms in international politics. Focusing specifically on the question of postcolonial agency, the article argues that the constructivist literature provides a distinctive spatial and temporal ordering of the ‘international’ that on the one hand can be seen to attribute agency to the postcolonial subject, while on the other can easily be interpreted as denying a presence for this subject. An alternative reading suggests that postcolonial agency is not only constituted by the international and its normative construction, but is also constituting, having the capacity to variously subvert and transform, but within limits. While some constructivist thinkers, primary among them being Christian Reus-Smit, recognise the normative order of the international as historically contested terrain, and where such contestation testifies to the role of the postcolonial world, how this role is articulated, and in what terms it is understood pose distinct challenges for understandings of agency and the constitution of the international. Focusing on Homi Bhabha and Franz Fanon, the article looks to how postcolonial thought can be mobilised to respond to this challenge, and to point to an alternative conception of the transformative potential of postcolonial agency. The turn to Bhabha and Fanon reveals such potential in both discursive and material terms so that where Bhabha can be said to frame agency and the terrain of the international in hybrid ideational terms, complementing Reus-Smit’s understanding of what can be termed the ‘postcolonial international’, Fanon’s more radical materialist ontology envisages agency in terms of embodied presence. This mobilisation of postcolonial thought provides the theoretical tools for conceptualising postcolonial subjectivity and articulations of agency in relation to the international and its constitution.
Mechanical nanogap switch for low-power on-board electronics
Authors: Yahiaoui Achref , Lemoine Emilien , Pothier Arnaud , Blondy Pierre
Published: June 2014

This paper presents the design fabrication and measurement of a nanogap radio frequency microelectromechanical system (RF MEMS) metal-contact switch. The prosed device generates a relatively high contact force with a low actuation voltage using a dielectric layer between the actuation electrode and the moveable beam. The actuation voltage is decreased with good reliability of the device by scaling down the gap. Beam geometry optimization allowed reaching 126 micronewtons contact force with only 10 V bias voltage. The fabricated miniature switch (80 × 50 × 0.95 µm) has indeed a pull-down voltage of 6 V and a contact resistance <2 Ω with 10 V bias applied. By measuring the S-parameters, the up-state capacitance has been fitted to 22 fF. The remarkable figure-of-merit Ron × Cup = 44 fs reflects the good performance of the device. A cycling test showed the device operated for 90 min without any charging problem noted.
No associations of prenatal maternal psychosocial stress with fasting glucose metabolism in offspring at 5–6 years of age
Authors: van Dijk A. E. , van Eijsden M. , Stronks K. , Gemke R. J. B. J. , Vrijkotte T. G. M.
Published: June 2014

Highly prevalent maternal psychosocial complaints are accompanied by increases in glucocorticoid stress hormones, which may predispose the offspring for type 2 diabetes and cardiovascular disease later in adulthood. The aim of the current research is to study whether prenatal maternal psychosocial stress is associated with parameters of blood glucose metabolism in their children aged 5–6 years. The study design was a prospective birth cohort (the Amsterdam Born Children and their Development study, the Netherlands). Depressive symptoms, pregnancy-related anxiety, parenting daily hassles and job strain were recorded by questionnaire (gestational week 16). A cumulative score was also calculated. Possible sex differences in the associations were considered. The subjects were 1952 mother–child pairs. Outcome measures were fasting glucose (n=1952), C-peptide and insulin resistance (HOMA2-IR) (n=1478) in the children at the age of 5–6 years. The stress scales, single and cumulative, were not associated with glucose/C-peptide/insulin resistance (allP>0.05). We did not find evidence for sex differences. In conclusion, we did not find evidence for an association between psychosocial stress during early pregnancy and parameters of glucose metabolism in offspring at the age of 5–6 years. Differences emerging later in life or in response to a metabolic challenge should not be ruled out.
Variants Close to NTRK2 Gene Are Associated With Birth Weight in Female Twins
Authors: Metrustry Sarah J. , Edwards Mark H. , Medland Sarah E. , Holloway John W. , Montgomery Grant W. , Martin Nicholas G. , Spector Tim D. , Cooper Cyrus , Valdes Ana M.
Published: June 2014

Low weight at birth has previously been shown to be associated with a number of adult diseases such as type 2 diabetes, cardiovascular disease, high blood pressure, and obesity later in life. Genome-wide association studies (GWAS) have been published for singleton-born individuals, but the role of genetic variation in birth weight (BW) in twins has not yet been fully investigated. A GWAS was performed in 4,593 female study participants with BW data available from the TwinsUK cohort. A genome-wide significant signal was found in chromosome 9, close to the NTRK2 gene (OMIM: 600456). QIMR, an Australian twin cohort (n = 3,003), and UK-based singleton-birth individuals from the Hertfordshire cohort (n = 2,997) were used as replication for the top two single nucleotide polymorphism (SNPs) underpinning this signal, rs12340987 and rs7849941. The top SNP, rs12340987, was found to be in the same direction in the Australian twins and in the singleton-born females (fixed effects meta-analysis beta = -0.13, SE = 0.02, and p = 1.48 × 10−8) but not in the singleton-born males tested. These findings provide an important insight into the genetic component of BW in twins who are normally excluded due to their lower BW when compared with singleton births, as well as the difference in BW between twins. The NTRK2 gene identified in this study has previously been associated with obesity.
Instrumentality and Expressiveness at Work
Authors: Sobiraj Sonja , Korek Sabine , Rigotti Thomas
Published: June 2014

Men’s professional work roles require different attributes according to the gender-typicality of their occupation (female- versus male-dominated). We predicted that levels of men’s strain and job satisfaction would be predicted by levels of self-ascribed instrumental and expressive attributes. Therefore, we tested for positive effects of instrumentality for men in general, and instrumentality in interaction with expressiveness for men in female-dominated occupations in particular. Data were based on a survey of 213 men working in female-dominated occupations and 99 men working in male-dominated occupations. We found instrumentality to be negatively related to men’s strain and positively related to their job satisfaction. We also found expressiveness of men in female-dominated occupations to be related to reduced strain when instrumentality was low. This suggests it is important for men to be able to identify highly with either instrumentality or expressiveness when regulating role demands in female-dominated occupations.