bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain-boundary-limited charge transport in solution-processed 6,13 bis(tri-isopropylsilylethynyl) pentacene thin film transistors
Authors: Chen Jihua , Tee Chee Keong , Shtein Max , Anthony John , Martin David C.
Published: June 2008

Grain boundaries play an important role in determining the electrical, mechanical, and optical properties of polycrystalline thin films. A side-disubstituted counterpart of pentacene, 6,13 bis(tri-isopropylsilylethynyl) (TIPS) pentacene, has lateral π-π packing and reasonably high solubility in a number of organic solvents. In this paper, the effects of grain boundaries on the effective hole mobility, on/off ratio, threshold voltage, and hysteresis of transistor transfer characteristics were investigated in solution-processed TIPS pentacene thin film transistors with both experiments and simulations. The effects of solvent type, concentration, substrate temperature, and evaporation rate were investigated by optical, electron, and atomic force microscopies. An apparatus for controlled solution casting was designed, fabricated, and used to make TIPS pentacene thin film transistors with more precisely controlled variations in microstructure and defect densities. First, hysteresis in the electrical characteristics was found to correlate directly with grain width WG (the crystal dimension along [12¯0]) in active layers. In addition, since TIPS pentacene crystals with larger grain width (WG>6 μm) generally took a long needle shape and the ones with smaller domain sizes (WG<4 μm) had a more equiaxed geometry, a sharp enhancement in the effective mobility was observed in the larger grains. In devices with active layers cast from toluene solution, the measured field-effect hole mobility for grain width WG smaller than 4 μm was generally ≤0.01 cm2/V s, whereas mobility for films with grain width WG>6 μm was typically 0.1∼1 cm2/V s. A model of boundary-limited transport was developed and used to explain experimental data. Based on the proposed model and an energy barrier (EB) on the order of 100 meV for electrical transport across grain boundary, the effective grain-boundary mobility μGBo was estimated to be approximately 5×10−7 cm2/V s.
A semianalytical solution for the 3ω method including the effect of heater thermal conduction
Authors: Gurrum Siva P. , King William P. , Joshi Yogendra K.
Published: June 2008

A semianalytical solution for the 3ω method is derived to account for thermal conduction within the metallic heater. The existing uniform heat flux approximation between the metal heater and substrate is replaced by a more realistic uniform heat generation condition within the metal heater. Although this correction does not affect thermal conductivity measurements in the original 3ω method, it is shown that significant errors can result when it is applied for thermal conductivity anisotropy measurements. For low thermal conductivity films, the error in the anisotropy ratio can be as high as 50%.
Planar microdischarge device for high-speed infrared thermography: Application of selenium-doped silicon detectors
Authors: Astrov Yu. A. , Portsel L. M. , Lodygin A. N. , Shuman V. B.
Published: June 2008

The authors investigated a possibility to develop a technique for high-speed and high-sensitivity imaging in the infrared range of light. The corresponding study was done by applying a planar microdischarge device that was a semiconductor-gas-discharge image converter. The requirements for developing the semiconductor component of the device were formulated to enhance the high-speed performance of the device. To meet these demands, extrinsic selenium-doped silicon detectors were developed. The doping of the semiconductor with selenium was done by high-temperature diffusion of the element from the vapor phase. To find the optimal conditions for the preparation of detectors, the efficiency of doping silicon with selenium as a function of the selenium vapor pressure was studied. The operation of the microdischarge device where the developed detectors were applied was investigated. This study demonstrates that converters equipped with Se:Se detectors can provide imaging of objects heated to temperature Tmin∼200°C with a temporal resolution on the order of 10−6s and a spatial resolution of ∼5lines∕mm.
A micro-/nanothermosize refrigerator and its performance analysis
Authors: Nie Wenjie , He Jizhou , He Xian
Published: June 2008

Based on the so-called thermosize effects similar to thermoelectric effects, the cycle model of a micro-/nanothermosize refrigerator composed of two isothermal and two isobaric processes is established. The working fluid in this cycle consists of atoms in an ideal gas confined in micro-/nanoscale. The detailed expressions for the rate of refrigeration and coefficient of performance are derived in the two cases of reversible and irreversible heat exchanges. Some important performance characteristic curves are plotted. The optimal performance parameters of the micro-/nanothermosize refrigerator are obtained by numerical calculation. The results obtained here will provide theoretical guidance for designing of a micro-/nanoscaled refrigerator.
Evidence of satellite valley position in GaN by photoexcited field emission spectroscopy
Authors: Yilmazoglu O. , Pavlidis D. , Hartnagel H. L. , Evtukh A. , Litovchenko V. , Semenenko N.
Published: June 2008

GaN field emitter rods with nanometer diameter were fabricated by photoelectrochemical etching on a n+-GaN substrate. Their electron field emission properties were investigated under ultraviolet (UV) illumination. The Fowler–Nordheim plots of the emission current show different slopes for nonilluminated and UV illuminated devices. A model based on the electron emission from valleys having different specific electron affinities is proposed to explain the experimental results. In the absence of illumination, the GaN rods are almost fully depleted and emission takes place only from the lower valley. Upon UV illumination and presence of a high electric field at the emitter tip, the upper valley of the conduction band appears to be occupied by electrons generated at the valence band. The energy difference between the lower and upper valleys was determined to be 1.15eV and is in good agreement with formerly published theoretical and measured values.
A unified phenomenological analysis of the experimental velocity curves in molecular motors
Authors: Ciudad Aleix , Sancho J. M.
Published: June 2008

We present a unified phenomenological kinetic framework to analyze the experimental data of several motor proteins (either linear or rotatory). This formalism allows us to discriminate the characteristic times of most relevant subprocesses. Explicitly, internal mechanical as well as chemical times are taken into account and joined together in a full-cycle time where effusion, diffusion and chemical rates, viscoelastic friction, and overdamped motion are considered. This approach clarifies the most relevant mechanisms in a particular motor by using the available experimental data of velocity versus external load and substrate concentration. We apply our analysis to three real molecular motors for which enough experimental data are available: the bacterial flagellar motor [Yoshiyuki et al., J. Mol. Biol. 377, 1043 (2003)], conventional kinesin (kinesin-1) [Block et al., Proc. Natl. Acad. Sci. U.S.A. 100, 2351 (2003)], and a RAN polymerase [Abbondanzieril, Nature (London) 438, 460 (2003)]. Moreover, the mechanism of stalling a motor is revised and split into two different concepts (mechanical and chemical stalling) that shed light to the understanding of backstepping in kinesin-1.
Full-dimensional quantum calculations of ground-state tunneling splitting of malonaldehyde using an accurate ab initio potential energy surface
Authors: Wang Yimin , Braams Bastiaan J. , Bowman Joel M. , Carter Stuart , Tew David P.
Published: June 2008

Quantum calculations of the ground vibrational state tunneling splitting of H-atom and D-atom transfer in malonaldehyde are performed on a full-dimensional ab initio potential energy surface (PES). The PES is a fit to 11 147 near basis-set-limit frozen-core CCSD(T) electronic energies. This surface properly describes the invariance of the potential with respect to all permutations of identical atoms. The saddle-point barrier for the H-atom transfer on the PES is 4.1kcal∕mol, in excellent agreement with the reported ab initio value. Model one-dimensional and “exact” full-dimensional calculations of the splitting for H- and D-atom transfer are done using this PES. The tunneling splittings in full dimensionality are calculated using the unbiased “fixed-node” diffusion Monte Carlo (DMC) method in Cartesian and saddle-point normal coordinates. The ground-state tunneling splitting is found to be 21.6cm−1 in Cartesian coordinates and 22.6cm−1 in normal coordinates, with an uncertainty of 2–3cm−1. This splitting is also calculated based on a model which makes use of the exact single-well zero-point energy (ZPE) obtained with the MULTIMODE code and DMC ZPE and this calculation gives a tunneling splitting of 21–22cm−1. The corresponding computed splittings for the D-atom transfer are 3.0, 3.1, and 2–3cm−1. These calculated tunneling splittings agree with each other to within less than the standard uncertainties obtained with the DMC method used, which are between 2 and 3cm−1, and agree well with the experimental values of 21.6 and 2.9cm−1 for the H and D transfer, respectively.
dc leakage behavior and conduction mechanism in (BiFeO3)m(SrTiO3)m superlattices
Authors: Ranjith R. , Prellier W. , Cheah Jun Wei , Wang Junling , Wu Tom
Published: June 2008

Leakage current behavior of (BiFeO3)m(SrTiO3)m superlattice structures was studied and analyzed at different temperatures (303–473K) in the light of various models. While bulk limited Poole–Frenkel emission was observed to dominate the leakage current in the temperature range of 303–383K, the space charge limited conduction was observed up to 473K. With a Poole–Frenkel emission type of conduction, the activation energy range of ∼0.06–0.25eV was calculated. The physical parameters, calculated from the analysis, correlate with the intrinsic properties. Such analysis of leakage current facilitates interface engineering of heterostructures for device applications.
Plasma actuated heat transfer
Authors: Roy Subrata , Wang Chin-Cheng
Published: June 2008

We introduce plasmas for film cooling enhancement in gas turbines and other engineering applications. We identify mechanisms to actuate essentially stagnant fluid just downstream of the cooling hole by employing three-dimensional body force for different hole geometries. Such methods actively alter flow structures in the vicinity of an actuator using an electrodynamic mechanism that induces attachment of cold jet to the work surface. Numerical results are compared with published experimental data and other numerical predictions for the latest film cooling technology. An effectiveness improvement of above 100% over the standard baseline design is predicted.
Constraints on micro-Raman strain metrology for highly doped strained Si materials
Authors: O’Reilly L. , Horan K. , McNally P. J. , Bennett N. S. , Cowern N. E. B. , Lankinen A. , Sealy B. J. , Gwilliam R. M. , Noakes T. C. Q. , Bailey P.
Published: June 2008

Ultraviolet (UV), low penetration depth, micro-Raman spectroscopy, and high-resolution x-ray diffraction (HRXRD) are utilized as complementary, independent stress characterization tools for a range of strained Si samples doped by low energy (2keV) Sb ion implantation. Following dopant implantation, good agreement is found between the magnitudes of strain measured by the two techniques. However, following dopant activation by annealing, strain relaxation is detected by HRXRD but not by micro-Raman. This discrepancy mainly arises from an anomalous redshift in the Si Raman peak position originating from the high levels of doping achieved in the samples. This has serious implications for the use of micro-Raman spectroscopy for strain characterization of highly doped strained Si complementary metal-oxide semiconductor devices and structures therein. We find a direct correlation between the Si Raman shift and peak carrier concentration measured by the differential Hall technique, which indicates that UV micro-Raman may become a useful tool for nondestructive dopant characterization for ultrashallow junctions in these Si-based materials.
Superior hydrogen desorption kinetics of Mg(NH2)2 hollow nanospheres mixed with MgH2 nanoparticles
Authors: Xie Lei , Li Yaoqi , Yang Rong , Liu Yang , Li Xingguo
Published: June 2008

Mg 3 N 2 nanocubes were prepared by vaporized bulk magnesium in ammonia atmosphere associated with plasma metal reaction. Then the product transformed to Mg(NH2)2 hollow nanospheres after it was reacted with NH3 based on the Kirkendall effect. The electron microscopy results suggested that the obtained hollow nanospheres were around 100nm and the shell thickness was about 10nm. Because of its short distance for Mg2+ diffusion and large specific surface area for interaction between Mg(NH2)2 and MgH2, the structure dramatically enhanced the hydrogen desorption kinetics of Mg(NH2)2–2MgH2.
Structural degradation and optical property of nanocrystalline ZnO films grown on Si (100)
Authors: Yang Boqian , Kumar Ashok , Feng Peter , Katiyar R. S.
Published: June 2008

Structural degradation of nanocrystalline ZnO films was observed with an increase in films thickness. Nanocrystalline epitaxial thin film with thickness of ∼170nm changed to polycrystalline ∼900nm with an increase in deposition time. Surface morphology revealed an average grain size of 30–50nm. Spatial correlation model indicated structural disorder due to relative disorientation of crystalline phases at nanoscale. The photoluminescence spectra showed free exciton (FX) ∼3.31eV, donor bound-exciton (DoX) ∼3.26 and donor-acceptor-pair (DAP) ∼3.22eV for thin films, which redshift, i.e., FX ∼3.30, DoX ∼3.24eV, and DAP ∼3.19–3.17eV for thicker films (400–900nm).
Dispersion of an optodynamic wave during its multiple transitions in a rod
Authors: Požar T. , Petkovšek R. , Možina J.
Published: June 2008

A rod acquires linear momentum during a short-laser-pulse ablation of its front face. Initially, this momentum is localized within the propagating laser-induced mechanical pulse—the optodynamic wave—while later it is gradually transferred to the uniform motion of the entire rod. Among other effects, the dispersion of the optodynamic wave due to lateral inertia plays an important role in the linear-momentum transformation mechanism. We observed the dispersion using interferometric measurements of the rod’s rear-end staircaselike displacement. The displacements calculated using an analytical solution of Love’s equation for a laser-ablated free-free homogeneous rod agree well with our measured data.
Vertical structure p-type permeable metal-base organic transistors based on N,N′-diphentyl-N,N′-bis(1-naphthylphenyl)-1,1′-biphenyl-4,4′-diamine
Authors: Huang Jinying , Yi Mingdong , Ma Dongge , Hümmelgen Ivo A.
Published: June 2008

In this article, vertical structure p-type permeable-base organic transistors were proposed and demonstrated. A hole-type organic semiconductor N,N′-diphentyl-N,N′-bis(1-naphthylphenyl)-1,1′-biphenyl-4,4′-diamine was used as emitter and collector. In the permeable-base transistors, the metal base was formed by firstly coevaporating Al and Ca in vacuum and then annealing at 120°C for 5min in air, followed by a thin Al deposition. These devices show a common-base current gain of near 1.0 and a common-emitter current gain of ∼270.
Nano-optics with spin waves at microwave frequencies
Authors: Demidov Vladislav E. , Demokritov Sergej O. , Rott Karsten , Krzysteczko Patryk , Reiss Guenter
Published: June 2008

With the recent development in nanoscale patterning techniques, the potential of practical applications of nanometer-size structures for signal processing has been growing continuously. Experimental findings on the manipulation of optical signals in nanostructures have recently given rise to a widely addressed scientific area—subwavelength nano-optics. Here, we demonstrate that spin waves in microscopic ferromagnetic film structures represent a superb object for realization of the principles of nano-optics in the microwave frequency range. We show experimentally that by using the unique properties of spin waves, one can easily channelize, split, and manipulate submicrometer-width spin-wave beams propagating in microscopic magnetic-film waveguides.
Q
-factor and density of optical modes in pyramidal and cone-shaped GaAs microcavities
Authors: Karl M. , Beck T. , Li S. , Kalt H. , Hetterich M.
Published: June 2008

GaAs pyramids on top of GaAs∕AlAs distributed Bragg reflectors (DBRs) are studied as candidates for microcavities with low mode volume. Photoluminescence spectra of single pyramids with embedded quantum dots show cavity modes with quality (Q-) factors of up to 700. Furthermore, to assess the complex mode structure in pyramids a finite-difference time-domain simulation with rotational symmetry is used to evaluate cavity modes in a cone on top of a DBR. A cone angle around 46° was identified for highest Q-factors. Based on our calculations, approaches to improve the light confinement are suggested which should result in microcavities with high Q-factors.
Pitfalls of ultrasound guided vascular access: the use of three/four‐dimensional ultrasound
Authors: French J. L. H. , Raine‐Fenning N. J. , Hardman J. G. , Bedforth N. M.
Published: June 2008

The use of ultrasound guidance for central venous access is widespread and was recommended as the technique of choice by The National Institute of Clinical Excellence in the UK in 2002. However, complications have been reported using this technique. In this article we review the technique of two‐dimensional ultrasound needle guidance and the errors that can occur. We then discuss the development of three‐ and four‐dimensional ultrasound and describe our experiences using this imaging modality in simulated and actual needle‐guidance. We discuss the potential advantages for clinicians utilising this newer form of ultrasound imaging for central venous access.
Renal replacement therapy for acute renal failure: a survey of practice in adult intensive care units in the United Kingdom
Authors: Gatward J. J. , Gibbon G. J. , Wrathall G. , Padkin A.
Published: June 2008

This study surveyed current practice in adult intensive care units in the United Kingdom in three key areas of renal replacement therapy when used for acute renal failure: type of therapy used, typical treatment dose and anticoagulation.

Responses were received from 303 (99%) of the 306 intensive care units. 269 units (89%) provide renal replacement therapy for acute renal failure. Most (65%) use continuous veno‐venous haemofiltration as first‐line therapy in the majority of patients, though continuous veno‐venous haemodiafiltration is used by 31% of units. For haemofiltration, the median typical treatment dose (interquartile range [range]) is 32 ml.kg−1.h−1 (28.6–35.7 [14.3–85.7]), with 49% using a treatment dose of 35 ml.kg−1.h−1 or greater. For haemodiafiltration, the median typical treatment dose (interquartile range [range]) is 44 ml.kg−1.h−1 (28.6–57.1 [21.4–120.7]), with 67% using a treatment dose of 35 ml.kg−1.h−1 or greater. The vast majority of intensive care units use intravenous unfractionated heparin (96%) or epoprostenol (88%) for anticoagulation. Dosage and monitoring of these two agents vary markedly between units. No units use citrate anticoagulation. These results reveal a wide variety of practice in the delivery of renal replacement therapy between intensive care units in the United Kingdom.
The influence of maternal depression, caregiving, and socioeconomic status in the post‐natal year on children's language development
Authors: Stein A. , Malmberg L.‐E. , Sylva K. , Barnes J. , Leach P. ,   the FCCC team
Published: June 2008

Background  Post‐natal depression is common and has been associated with adverse effects on children's later emotional and behavioural development. The evidence for effects on children's cognitive development is unclear but this could potentially be a major public health issue. The aim was to examine whether maternal depression and maternal caregiving during the first year of life are associated with children's subsequent language development.

Methods  One thousand two hundred and one women were recruited from antenatal and post‐natal baby clinics in two areas in England, and followed up until their babies were 3 years. Mothers and children were assessed by questionnaire, interview and home observation; 999 children's language was assessed at 36 months, although 55 were excluded principally because they had been exposed to insufficient English.

Results  In bivariate analyses maternal depressive symptomatology in the post‐natal year but not at 36 months was associated with poorer child language at 36 months; maternal caregiving, was positively associated with language. Structural Equation Modelling revealed that depression was associated with poorer caregiving but was not independently associated with language. Higher quality caregiving at 10 months was associated with better language. When the sample was split by socioeconomic factors the effects of depression on caregiving were stronger in the less advantaged group. In both groups poorer quality early caregiving predicted lower language outcome.

Conclusions  Post‐natal depression had a negative effect on caregiving, which in turn affected language; post‐natal depression did not have an additional direct effect on language. Socioeconomic factors moderated the effects of depression on caregiving. When targeting interventions at mothers with post‐natal depression, it may be strategic to focus on lower socioeconomic groups at higher risk.
How does cot death prevention advice influence parents' behaviour?
Authors: Miller L. H. , Fraser A. , Moy R.
Published: June 2008

Objective  To explore parents’ understanding of the recommended cot death prevention strategies, and to discuss what they are doing in practice. If there is a difference between knowledge and implementation measures, possible reasons for this will be considered.

Study design  A qualitative study using thematic analysis, aimed at finding out attitudes and opinions of parents about cot death prevention measures. Twelve participants were interviewed from two disadvantaged communities in south Birmingham.

Results  Parents found that much of the cot death prevention advice they were provided with was conflicting and caused confusion. As such, many parents chose to follow advice from non‐healthcare sources. Some parents were carrying out preventative measures but were not aware of the reason for doing it. Many felt they did not receive enough advice relating to cot death prevention.

Conclusion  Cot death health promotion advice appears to be inadequate among patients from a deprived socioeconomic background. Some of these issues could be resolved with increased training addressing these matters.
Health‐related quality of life of very preterm infants at 1 year of age after two developmental care‐based interventions
Authors: Van Der Pal S. M. , Maguire C. M. , Bruil J. , Le Cessie S. , Wit J. M. , Walther F. J. , Veen S.
Published: June 2008

Background  In the context of a growing interest in developmental care (DC) this study explores the effect of the basic elements of DC and the additional effect of the individual approach of the Newborn Individualized Developmental Care and Assessment Program (NIDCAP) on the health‐related quality of life (HRQoL) of very preterm infants at 1 year of age. The basic elements of DC in this study were defined as the use of standardized nests and incubator covers whose protective characteristics were hypothesized to have a positive effect on the infant's HRQoL. The individualized approach of the NIDCAP was thought to further increase HRQoL.

Methods  Very preterm (≤32 weeks) born infants in a Dutch Neonatal Intensive Care Unit at two locations were included in two consecutive randomized controlled trials (RCT) comparing controls (standard care) with basic DC (standardized nests and covers) in the first RCT and basic DC with NIDCAP in the second RCT. Parents completed a questionnaire (RCT 1, n = 136; RCT 2, n = 128) regarding their infant's HRQoL (TNO‐AZL Preschool Quality of Life Questionnaire) at 1 year of age, corrected for prematurity. Because of multiple testing a P‐value of below 0.01 was chosen to indicate significance.

Results  HRQoL scores ranged from good to optimal for most infants. No significant differences were found between basic DC vs. controls and NIDCAP vs. basic DC on the child's HRQoL as reported by parents at 1 year of age.

Conclusions  These two RCT show that the basic elements of DC and the more individualized NIDCAP do not improve HRQoL of very preterm infants at 1 year of age.
Internalizing disposition and preschool children's cortisol fluctuations
Authors: Li I. , Shen P‐S.
Published: June 2008

Background  Research on the impact of childcare suggested that young children's cortisol tends to increase or remain ‘flat’ across the day while their cortisol levels follow the typical circadian decrease between mid‐morning and mid‐afternoon at home. However, studies are needed to investigate what is happening to cortisol levels and whether individual variation exists in the cortisol rhythm in childcare.

Methods  Internalizing disposition was examined as a possible moderator of cortisol‐linked stress response of young children in full‐time, centre‐based childcare. Ambulatory salivary sampling for cortisol was performed on 37 preschoolers at four different times for 10 consecutive school days. In order to test the interaction effect of internalizing disposition on cortisol levels, children were divided into four groups – the most internalizing group, the least internalizing group, and two groups in between, based on teacher‐rated ‘approach’ scores.

Results  Repeated measure analyses of variance with polynomial contrast for time indicated that (1) a linear trend of significant increase between mid‐morning and mid‐afternoon exists for all children without group interactions; (2) quadratic and cubic trends exist and the interaction effects among the groups are significant, meaning the four groups are different in fluctuation pattern. Further analyses demonstrated that (1) the least internalizing children showed significant decreases in cortisol levels from morning to noon and after nap, although there is a considerable increase after lunch, (2) cortisol levels of the other three groups across the day fit the pattern of upward curve.

Conclusion  The tradition of the field in comparing mid‐morning and mid‐afternoon levels of cortisol as an indicator of childcare effect may not reflect individual variation in the fluctuation patterns of cortisol. Moderating effect of child characteristics needs to be considered in future research of childcare effect.
Effect of aromatizable and unaromatizable androgen replacement in hypogonadal men on GH responsiveness
Authors: Gleeson Helena K. , Shalet Stephen M.
Published: June 2008

Objectives  Although studies have clearly demonstrated that oestrogen replacement affects GH responsiveness by causing relative GH resistance, the effect of androgen replacement is unknown. Circumstantial evidence only suggests that androgen replacement may increase GH sensitivity and/or responsiveness. To examine the impact of androgens on GH responsiveness, hypogonadal men underwent the IGF‐1 generation test in the unreplaced state, replaced with testosterone (T) and also replaced with dihydrotestosterone (DHT), its nonaromatizable metabolite.

Design and patients  Twelve hypogonadal men with a normal GH axis were recruited. Each subject in random order had 4 weeks off T (NoRx), 4 weeks on T gel (TG) and 4 weeks on DHT gel (DHTG) applied daily, with 1 week washout between each preparation. An IGF‐1 generation test using a subcutaneous injection of 7 mg of GH was performed at the end of each of these 4‐week phases.

Measurements  Serum GHBP, total and free IGF‐1, IGFBP‐3 and acid‐labile subunit (ALS) levels were measured at baseline and 24 h (peak) after GH administration.

Results  Despite a decrease in GHBP during the TG and DHTG phases, there were no observed differences in baseline, peak or increment (peak – baseline) total or free IGF‐1 between the NoRx, TG or DHTG phases.

Conclusions  There is no evidence of fluctuation in GH responsiveness in hypogonadal men, untreated or replaced with T or DHT alone. This implies that the increased level of oestradiol as a consequence of T replacement in hypogonadal men does not impact significantly on GH responsiveness, nor is there evidence of an androgen effect with elevated DHT levels as a consequence of either T or DHT replacement.
Invertebrate community patterns in Mediterranean temporary wetlands along hydroperiod and salinity gradients
Authors: WATERKEYN ALINE , GRILLAS PATRICK , VANSCHOENWINKEL BRAM , BRENDONCK LUC
Published: June 2008

1. Temporary aquatic habitats often are inhabited by a unique fauna and flora and contribute significantly to regional diversity. Temporary wetlands around the world are disappearing rapidly. The individual and interacting impacts of factors influencing community structure and dynamics in temporary wetlands are not always well known.

2. Camargue wetlands are mainly characterized by variable salinity and hydroperiod. The individual and combined impacts of these local factors, together with regional variables, on invertebrate communities remain unknown. We therefore characterized and sampled invertebrates in 30 temporary wetlands along salinity and hydroperiod gradients in the Camargue (Southern France) 3, 5 and 7 months after inundation.

3. Over the three sampling occasions, a total of 17 cladoceran species and 49 macroinvertebrate taxa were identified. Hydroperiod and salinity were the most important variables explaining variation in taxonomic composition and can be considered key factors shaping the invertebrate communities in Camargue wetlands. The impact on taxon richness was significantly positive for hydroperiod but significantly negative for salinity. Regional factors had no significant effect on the structure of the studied invertebrate communities, suggesting that dispersal was not limiting and that species sorting was the most important structuring process.

4. The results of this study suggest that the combined and interacting effects of salinization and hydrological modification of Mediterranean temporary wetlands (due to water management, climate change, etc.) can result in reduced diversity in large numbers of Mediterranean wetlands and induce a considerable decline in regional diversity of aquatic invertebrates.
Exploring managerial factors affecting ERP implementation: an investigation of the Klein‐Sorra model using regression splines
Authors: Osei‐Bryson Kweku‐Muata , Dong Linying , Ngwenyama Ojelanki
Published: June 2008

Abstract.Predicting successful implementation of enterprise resource planning (ERP) systems is still an elusive problem. The cost of ERP implementation failures is exceedingly high in terms of quantifiable financial resources and organizational disruption. The lack of good explanatory and predictive models makes it difficult for managers to develop and plan ERP implementation projects with any assurance of success. In this paper we investigate the Klein & Sorra theoretical model of implementation effectiveness. To test this model we develop and validate a data collection instrument to capture the appropriate data, and then use multivariate adaptive regression splines to examine the assertions of the model and suggest additional significant relationships among the factors of their model. Our research offers new dimensions for studying managerial interventions in IT implementation and insights into factors that can be managed to improve the effectiveness of ERP implementation projects.
A model for online learner support based on selecting appropriate peer tutors
Authors: Van Rosmalen P. , Sloep P.B. , Brouns F. , Kester L. , Berlanga A. , Bitter M. , Koper R.
Published: June 2008

Tutors have only limited time to support students. In this paper, we discuss a model that addresses the question of how to help students answer content‐related questions. A small group of students is created, which consists of the student who asked the question and peers who should be able to answer it. Criteria used to compose the group are the content of the question in relation to the knowledge and skills of the peers. The model supports the collaboration with text fragments selected from the study materials. We will introduce the model and briefly discuss the results of the calibration and a simulation of the model. Finally, we will discuss the outcome of an experiment with two groups of approximately 50 students who used the model for a period of 8 weeks. The results indicate that the students positively value the model and that it is possible to resolve a substantial number of their questions.
Preventive and post‐infection control of Botrytis cinerea in tomato plants by hexanoic acid
Authors: Leyva M. O. , Vicedo B. , Finiti I. , Flors V. , Del Amo G. , Real M. D. , García‐Agustín P. , González‐Bosch C.
Published: June 2008

The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration‐ and pH‐dependent manner, and stopped spore germination at a very early stage, preventing germ‐tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 mm. Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 mm. Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of spermine, spermidine, putrescine and cadaverine in B. cinerea mycelia. Spray application of hexanoic acid at fungicidal concentrations on 4‐week‐old tomato plants prior to fungal inoculation reduced necrosis diameter by approximately 60%. Application of the same hexanoic acid concentrations on previously infected plants reduced further necrosis expansion by around 30%. The results suggest that this chemical acts as a preventive and curative fungicide. Interestingly, treatments with hexanoic acid at concentrations below the MFC in hydroponic solution prior to fungal inoculation significantly reduced necrosis area. These results suggest an inducer effect of plant responses for hexanoic acid treatments at these concentrations. Hexanoic acid is a good candidate for safe antifungal treatments for the control of B. cinerea, which is responsible for many economic losses on fruits, vegetables and flowers.
Epigenetic regulation of Th2 cytokine expression in atopic diseases
Authors: Van Panhuys N. , Le Gros G. , McConnell M. J.
Published: June 2008

The immune response to allergens starts with stimulation of a naïve T helper (Th) cell and its differentiation into a Th2 cell, expressing the cytokines interleukin (IL)‐4, IL‐5 and IL‐13 responsible for the allergic response. The initial pattern of cytokine expression is retained during restimulation and division of the Th2 cell to create a population of specific allergen‐responsive memory Th2 cells. Both, the coordinate cytokine expression and the inherited cytokine memory are specified by epigenetic mechanisms. Th2‐specific changes in chromatin configuration at the Th2 locus act locally to open DNA, allowing recruitment of transcriptional machinery and rapid induction of cytokine expression. Induction of the transcription factor GATA3 is critical to this process. Loss of DNA methylation at the Th2 locus during differentiation from a naïve Th cell correlates to increased histone acetylation, consistent with the expression of IL‐4, IL‐5 and IL‐13. The silencing of the Th2 locus in Th1 cells was associated with repressive histone methylation. These data indicate the formation of a ‘poised’ chromatin configuration at the Th2 locus that in combination with specific transcription factors specifies the cytokine repertoire in daughter cells and allows the immediate, rapid induction of cytokines by those cells in response to allergen.
Relative susceptibility of oaks to seven species of Phytophthora isolated from oak forest soils
Authors: Balci Y. , Balci S. , MacDonald W. L. , Gottschalk K. W.
Published: June 2008

Isolates of Phytophthora cambivora, P. cinnamomi, P. citricola, P. europaea, P. quercetorum and two unidentified species were tested for their pathogenicity to eastern US oak species by root and stem inoculations. Experiments were conducted during two different periods and included 1‐, 2‐ and 20‐year‐old oaks grown under greenhouse and field conditions. Species of Phytophthora were pathogenic in varying degrees to the oak species tested. All species were pathogenic to fine and taproots of at least one oak species. The fine root damage caused by the species of Phytophthora ranged from 9 to 55% when compared to the controls. Roots were more susceptible during the fall inoculation period than the summer. With exception of Phytophthora sp1 and P. quercina‐like, all species of Phytophthora were pathogenic to oak stems with P. cinnamomi and P. citricola being the most aggressive. Quercus montana and Q. rubra were the most susceptible oak species to stem inoculation. Lesion sizes were considerably larger when 20‐year‐old trees were inoculated. Generally, no significant differences in lesion sizes were detected in greenhouse tests when the summer and fall inoculation periods were compared. However, on 2‐year‐old field‐grown seedlings, lesion sizes were considerably smaller or not significantly different from controls during the fall inoculation period, suggesting lower, late season temperatures may restrict lesion development.
Cervical esophageal web and celiac disease
Authors: Sinha Saroj Kant , Nain Chander Kamal , Udawat Harsh Prasad , Prasad Kaushal Kishore , Das Reena , Nagi Birinder , Singh Kartar
Published: June 2008

Background and Aim:  There is paucity of prospective data on association between cervical esophageal webs and celiac disease. It is not clear whether all patients with cervical esophageal web need screening for celiac disease. Hence, the present study was carried out to determine the association of cervical esophageal web with celiac disease.

Methods:  This prospective study included consecutive patients with symptomatic cervical esophageal web diagnosed over a period of 4.5 years. Tissue transglutaminase antibody was measured in serum of each patient. Patients with elevated tissue transglutaminase antibody titer were subjected to esophagogastroduodenoscopy and biopsies were obtained from the descending duodenum to look for histological changes of celiac disease. Esophageal web was treated with bougie dilatation. Celiac disease was diagnosed on the basis of elevated tissue transglutaminase antibody and suggestive duodenal histology.

Results:  Twenty one patients were diagnosed to have cervical esophageal web. Eighteen (85.7%) had evidence of iron deficiency. Five (23.8%) patients with cervical esophageal web fulfilled criteria for diagnosis of celiac disease. All five had evidence of iron deficiency. None of these patients gave a history of chronic diarrhea. All patients were treated with bougie dilatation. Patients with celiac disease were advised of a gluten‐free diet. All five celiac disease patients are free of dysphagia without recurrence after a mean follow up of 10 months (range: 3 to 16 months).

Conclusions:  There is association between cervical esophageal web and celiac disease. All adult patients with cervical esophageal web and iron deficiency need screening for celiac disease even in the absence of chronic diarrhea.
Clinicopathological features and natural history of acute sporadic non‐(A‐E) hepatitis
Authors: Tassopoulos Nicolaos C , Papatheodoridis George V , Delladetsima Ioanna , Hatzakis Angelos
Published: June 2008

Aim:  The aim of the present study was to describe the clinicopathological characteristics and the natural history of acute non‐(A‐E) hepatitis and to assess the possible role of hepatitis G virus (HGV), TT virus (TTV) and mainly SEN virus (SENV).

Methods:  A cohort of 55 patients with sporadic acute non‐(A‐E) hepatitis with a mean follow up of 31 (6–55) months was studied.

Results:  The clinical presentation was fulminant in one (1.8%), protracted with impaired regeneration in seven (12.7%) and benign in the remaining 47 (85.5%) cases. Progression to chronic hepatitis was observed in 15 (27.3%) patients; it was more frequent in clinically severe than in non‐severe cases (five of eight patients or 62.5% vs 10 of 47 patients or 21.3%, P = 0.028). Six of 10 biopsied chronic non‐(A‐E) cases developed cirrhosis within 10–33 months. Serum HGV‐RNA was detected in 16 of 55 (29.1%) patients, TTV in 20 of 38 (52.6%) patients and SENV‐D/H DNA in 20 of 55 (36.4%) cases. HGV‐RNA was detected more frequently in clinically severe than in non‐severe cases (five of eight or 62.5% vs 11 of 47 or 23.4%, P = 0.038). There was no other association between the presence of HGV, TTV, or SENV infection and patient characteristics or severity and outcome of disease.

Conclusions:  HGV, TTV, and SENV do not seem to be responsible for the majority of sporadic acute non‐(A‐E) hepatitis cases. Our cohort further supports the existence of new, unknown hepatitis agent(s) with uncertain mode of transmission. The non‐(A‐E) agent(s) can also cause chronic hepatitis, which often has an aggressive course with rapid development of cirrhosis.
Prospective randomized study on the use of a computer‐based endoscopic simulator for training in esophagogastroduodenoscopy
Authors: Shirai Yasuyuki , Yoshida Tomoharu , Shiraishi Ryu , Okamoto Takeshi , Nakamura Hiroki , Harada Toshiya , Nishikawa Jun , Sakaida Isao
Published: June 2008

Background and Aim:  Computer‐based endoscopic simulators have been developed in recent years, and their usefulness has been reported. However, there is no blinded prospective randomized controlled study on esophagogastroduodenoscopy (EGD) training using virtual reality simulators. The present study aimed to assess the effectiveness of a computer‐based simulator for basic training in EGD.

Methods:  The GI‐Mentor II simulator was used. The subjects were 20 hospital medical residents. After receiving an explanation regarding the fundamentals of endoscopy, 10 trainees were each randomized into a simulator group and a non‐simulator group. The simulator group received 5 h of training with the GI‐Mentor II plus bedside training, while the non‐simulator group received bedside training. Subsequently, each subject performed endoscopy twice for assessment. Performance was evaluated according to a five‐grade scale for a total of 11 items.

Results:  The score was significantly higher in the skills required for insertion into the esophagus, passing from the esophagogastric junction (EGJ) to the antrum, passing through the pylorus, and examination of the duodenal bulb and the fornix.

Conclusions:  The performance of endoscopy was improved by 5 h of simulator training. The simulator was more effective with regard to the items related to manipulation skills. Computer‐based simulator training in EGD is useful for beginners.
Predictors of violent behavior among acute psychiatric patients: Clinical study
Authors: Amore Mario , Menchetti Marco , Tonti Cristina , Scarlatti Fabiano , Lundgren Eva , Esposito William , Berardi Domenico
Published: June 2008

Aim:  Violence risk prediction is a priority issue for clinicians working with mentally disordered offenders. The aim of the present study was to determine violence risk factors in acute psychiatric inpatients.

Methods:  The study was conducted in a locked, short‐term psychiatric inpatient unit and involved 374 patients consecutively admitted in a 1‐year period. Sociodemographic and clinical data were obtained through a review of the medical records and patient interviews. Psychiatric symptoms at admission were assessed using the Brief Psychiatric Rating Scale (BPRS). Psychiatric diagnosis was formulated using the Structured Clinical Interview for DSM‐IV. Past aggressive behavior was evaluated by interviewing patients, caregivers or other collateral informants. Aggressive behaviors in the ward were assessed using the Overt Aggression Scale. Patients who perpetrated verbal and against‐object aggression or physical aggression in the month before admission were compared to non‐aggressive patients, moreover, aggressive behavior during hospitalization and persistence of physical violence after admission were evaluated.

Results:  Violent behavior in the month before admission was associated with male sex, substance abuse and positive symptoms. The most significant risk factor for physical violence was a past history of physically aggressive behavior. The persistent physical assaultiveness before and during hospitalization was related to higher BPRS total scores and to more severe thought disturbances. Higher levels of hostility–suspiciousness BPRS scores predicted a change for the worse in violent behavior, from verbal to physical.

Conclusion:  A comprehensive evaluation of the history of past aggressive behavior and psychopathological variables has important implications for the prediction of violence in psychiatric settings.
Burden and coping strategies in mothers of patients with schizophrenia in Japan
Authors: Hanzawa Setsuko , Tanaka Goro , Inadomi Hiroyuki , Urata Minoru , Ohta Yasuyuki
Published: June 2008

Aim:  The present study was conducted to identify factors contributing to burden of care in 57 mothers caring for patients with schizophrenia.

Methods:  Members of the Federation of Families of People with Mental Illness in Nagasaki Prefecture were evaluated using well‐validated scales to evaluate burden of care (eight‐item short version of the Japanese version of the Zarit Caregiver Burden Interview), general health status (General Health Questionnaire 12‐item version), difficulty in life, coping strategies, emotional support, and understanding of mental illness and disorders.

Results:  Burden of care was significantly associated with general health status and difficulty in life.

Conclusion:  On multiple regression it was found that ‘social interests’ and ‘resignation’, both of which are the subscales of coping strategies, exerted significant and independent effects with respect to burden of care.