bluuebunny/crossref_metadata_2025 huggingface dataset:
Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots
Authors: Borselli M. G. , Eng K. , Croke E. T. , Maune B. M. , Huang B. , Ross R. S. , Kiselev A. A. , Deelman P. W. , Alvarado-Rodriguez I. , Schmitz A. E. , Sokolich M. , Holabird K. S. , Hazard T. M. , Gyure M. F. , Hunter A. T.
Published: August 2011

We demonstrate double quantum dots fabricated in undoped Si/SiGe heterostructures relying on a double top-gated design. Charge sensing shows that we can reliably deplete these devices to zero charge occupancy. Measurements and simulations confirm that the energetics are determined by the gate-induced electrostatic potentials. Pauli spin blockade has been observed via transport through the double dot in the two electron configuration, a critical step in performing coherent spin manipulations in Si.
Dynamic timber cell recognition using two-dimensional image measurement machine
Authors: Zhao Peng
Published: August 2011

Image motion blur and defocus blur often occur when there is a relative motion between the imaging camera and the detected object. In this paper, we propose a robust timber cell recognition scheme using the low quality color timber cell images with the above-mentioned image blurs. First, a novel two-dimensional image measurement machine is devised, to obtain the object images sequentially by using a color camera. Second, the image-moment-based blur invariant features are calculated. Third, timber cell recognition is performed by using the computed Euclidean distance based on the moment invariants. We have experimentally proved that the effective use of image blur information improves the recognition accuracy of camera-captured timber cells. Moreover, the allowed maximum translation speed of the moving gallery is also discussed theoretically and experimentally. This scheme can identify the timber species by means of the cell recognition so as to judge the physical property and economic value of different timber species correctly.
An empirical dependence of frequency in the oscillatory sorption of H2 and D2 in Pd on the first ionization potential of noble gases
Authors: Lalik Erwin
Published: August 2011

Oscillatory heat evolution in sorption of H2 and D2 in Pd can be induced by an admixture of ∼10 vol.% of an inert gas (He, Ne, Ar, Kr, or N2) to either isotope prior to its contact with palladium powder. The oscillations are represented in the form of a calorimetric time series, recorded using a gas flow-through microcalorimeter at the temperatures of 75 °C for D2 and 106 °C for H2. For both D2 and H2, the oscillation parameters change as a function of the kind of inert gas used: the amplitude increases and the frequency decreases in passing from He to Kr. An empirical dependence of the oscillation frequencies observed for various admixtures and normalized with respect to Kr has been found. Accordingly, the frequency is a function of a product of the first ionization potential and the square root of atomic mass of the inert gas (He, Ne, Ar, Kr, or N2). On the other hand, invariance of the thermal effects of sorption is evident from the integrated areas under the calorimetric time series yielding the molar heats of sorption conserved, irrespective of the inert gas admixture. A novel calibration procedure has been devised in order to deal with an instability of calibration factor arising in desorption of H2 and D2 from Pd. A method of dynamic calibration factor made it possible to obtain a good agreement between the heats of sorption and desorption of both H2 and D2 within individual sorption-desorption cycles for all inert gas admixtures.
Concurrent spinodal decomposition and surface roughening in thin solid films
Authors: Boyne A. , Dregia S. A. , Wang Y.
Published: August 2011

A computational model based on the phase field method is developed to investigate the morphological evolution of a thin solid film undergoing concurrent spinodal decomposition and surface roughening. It is found that there is a strong link between developing two-phase microstructures, surface roughness, and film break-up. A non-traditional film-to-island morphological transition is observed due to the presence of coherency stress in the film caused by phase separation.
Optical transition energies as a probe of stress in polycrystalline CdTe thin films
Authors: Li Jian , Chen Jie , Collins R. W.
Published: August 2011

In situ spectroscopic ellipsometry was applied to measure the dielectric functions ɛ of polycrystalline CdTe thin films prepared by magnetron sputtering. The observable critical point (CP) energies determined for the films in best fits to d2ɛ/dE2 are shifted relative to those for single crystal CdTe. The energy shift of the critical point designated as En is attributed to in-plane stress X with linear stress coefficient CX(En). By analyzing these shifts, it was found that stress (1) builds with thickness in as-deposited films, (2) relaxes with increasing substrate temperature at fixed thickness, and (3) is relaxed uniformly in CdCl2 treated films.
Degradation in InAlN/AlN/GaN heterostructure field-effect transistors as monitored by low-frequency noise measurements: Hot phonon effects
Authors: Kayis C. , Ferreyra R. A. , Wu M. , Li X. , Özgür Ü. , Matulionis A. , Morkoç H.
Published: August 2011

Low-frequency noise technique was applied to analyze performance of nearly lattice-matched InAlN/AlN/GaN heterostructure field-effect transistors and their degradation caused by electrical stress. Nearly identical devices from the same wafer have undergone a 7 h DC electrical stress at a fixed DC drain bias of VDS = 20 V and different gate biases. We noted up to 32 dB/Hz higher low-frequency noise for stressed devices over the entire frequency range of 1 Hz-100 kHz. The measurements showed the minimum degradation at a gate-controlled two-dimensional electron gas density of 9.4 × 1012 cm−2. This result is in good agreement with the reported stress effect on drain-current degradation and current-gain-cutoff-frequency measurements and consistent with the ultrafast decay of hot-phonons due to the phonon–plasmon coupling.
Stable folding core in the folding transition state of an α-helical integral membrane protein
Authors: Curnow Paul , Di Bartolo Natalie D. , Moreton Kathleen M. , Ajoje Oluseye O. , Saggese Nicholas P. , Booth Paula J.
Published: August 2011

Defining the structural features of a transition state is important in understanding a folding reaction. Here, we use Φ-value and double mutant analyses to probe the folding transition state of the membrane protein bacteriorhodopsin. We focus on the final C-terminal helix, helix G, of this seven transmembrane helical protein. Φ-values could be derived for 12 amino acid residues in helix G, most of which have low or intermediate values, suggesting that native structure is disrupted at these amino acid positions in the transition state. Notably, a cluster of residues between E204 and M209 all have Φ-values close to zero. Disruption of helix G is further confirmed by a low Φ-value of 0.2 between residues T170 on helix F and S226 on helix G, suggesting the absence of a native hydrogen bond between helices F and G. Φ-values for paired mutations involved in four interhelical hydrogen bonds revealed that all but one of these bonds is absent in the transition state. The unstructured helix G contrasts with Φ-values along helix B that are generally high, implying native structure in helix B in the transition state. Thus helix B seems to constitute part of a stable folding nucleus while the consolidation of helix G is a relatively late folding event. Polarization of secondary structure correlates with sequence position, with a structured helix B near the N terminus contrasting with an unstructured C-terminal helix G.
Demography and ecology drive variation in cooperation across human populations
Authors: Lamba Shakti , Mace Ruth
Published: August 2011

Recent studies argue that cross-cultural variation in human cooperation supports cultural group selection models of the evolution of large-scale cooperation. However, these studies confound cultural and environmental differences between populations by predominantly sampling one population per society. Here, we test the hypothesis that behavioral variation between populations is driven by environmental differences in demography and ecology. We use a public goods game played with money and a naturalistic measure of behavior involving the distribution of salt, an essential and locally valued resource, to demonstrate significant variation in levels of cooperation across 16 discrete populations of the same small-scale society, the Pahari Korwa of central India. Variation between these populations of the same cultural group is comparable to that found between different cultural groups in previous studies. Demographic factors partly explain this variation; age and a measure of social network size are associated with contributions in the public goods game, while population size and the number of adult sisters residing in the population are associated with decisions regarding salt. That behavioral variation is at least partly contingent on environmental differences between populations questions the existence of stable norms of cooperation. Hence, our findings call for reinterpretation of cross-cultural data on cooperation. Although cultural group selection could theoretically explain the evolution of large-scale cooperation, our results make clear that existing cross-cultural data cannot be taken as empirical support for this hypothesis.
Evaluation of multiple-sphere head models for MEG source localization
Authors: Lalancette M , Quraan M , Cheyne D
Published: August 2011

Magnetoencephalography (MEG) source analysis has largely relied on spherical conductor models of the head to simplify forward calculations of the brain's magnetic field. Multiple- (or overlapping, local) sphere models, where an optimal sphere is selected for each sensor, are considered an improvement over single-sphere models and are computationally simpler than realistic models. However, there is limited information available regarding the different methods used to generate these models and their relative accuracy. We describe a variety of single- and multiple-sphere fitting approaches, including a novel method that attempts to minimize the field error. An accurate boundary element method simulation was used to evaluate the relative field measurement error (12% on average) and dipole fit localization bias (3.5 mm) of each model over the entire brain. All spherical models can contribute in the order of 1 cm to the localization bias in regions of the head that depart significantly from a sphere (inferior frontal and temporal). These spherical approximation errors can give rise to larger localization differences when all modeling effects are taken into account and with more complex source configurations or other inverse techniques, as shown with a beamformer example. Results differed noticeably depending on the source location, making it difficult to recommend a fitting method that performs best in general. Given these limitations, it may be advisable to expand the use of realistic head models.
Genetic Diversity of a Brazilian Strain Collection of Xanthomonas citri subsp. citri Based on the Type III Effector Protein Genes
Authors: Jaciani F. J. , Ferro J. A. , Ferro M. I. T. , Vernière C. , Pruvost O. , Belasque J.
Published: August 2011

Exclusion and eradication or management based on an integrated approach with less susceptible varieties, copper-based bactericides, and windbreaks are the two main strategies used to prevent or control citrus canker. Field tolerance or resistance to citrus canker is not found in the most important commercial sweet orange cultivars, and pathogen-derived resistance has been developed and applied in different crops to obtain resistant genotypes to plant pathogens. We describe the development of DNA primers and probes based on the type III effector genes avrXacE1, avrXacE2, avrXacE3, avrBs2, pthA4, hpaF, and XAC3090 (leucine rich protein), and their application in the evaluation of the genetic diversity of the pathogen. A total of 49 haplotypes were identified in 157 strains by Southern blot analysis. No genetic polymorphism was detected by BOX elements - and enterobacterial repetitive intergenic consensus–polymerase chain reaction (ERIC-PCR) analysis, nor with the genes avrBs2, XAC3090, and hpaF. Nei's genetic diversity indexes varied from 0.65 to 0.96 for subcollections of the pathogen. One or few haplotypes were most frequent in the strain collection, but several haplotypes were represented by solely one or few strains. The PthA4 probe resulted in the higher number of haplotypes identified in the Brazilian subcollections. Greater variation in the frequency of haplotypes occurred within subcollections (93.7%) than among subcollections. Only some haplotypes were genetically distant from all others, especially those originated from Rio Grande do Sul and Santa Catarina states. These bacterial effectors are widely spread in the collections and are useful for a better understanding of the host–pathogen interaction and the search for resistance genes in host and nonhost plants.
The extraordinary athletic performance of leaping gibbons
Authors: Channon Anthony J. , Usherwood James R. , Crompton Robin H. , Günther Michael M. , Vereecke Evie E.
Published: August 2011

The distance that animals leap depends on their take-off angle and velocity. The velocity is generated solely by mechanical work during the push-off phase of standing-start leaps. Gibbons are capable of exceptional leaping performance, crossing gaps in the forest canopy exceeding 10 m, yet possess none of the adaptations possessed by specialist leapers synonymous with maximizing mechanical work. To understand this impressive performance, we recorded leaps of the gibbons exceeding 3.7 m. Gibbons perform more mass-specific work (35.4 J kg−1) than reported for any other species to date, accelerating to 8.3 ms−1in a single movement and redefining our estimates of work performance by animals. This energy (enough for a 3.5 m vertical leap) is 60 per cent higher than that achieved by galagos, which are renowned for their remarkable leaping performance. The gibbons' unusual morphology facilitates a division of labour among the hind limbs, forelimbs and trunk, resulting in modest power requirements compared with more specialized leapers.
Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach
Authors: Nakata Toshiyuki , Liu Hao
Published: August 2011

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth,Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements.
RopGEF7Regulates PLETHORA-Dependent Maintenance of the Root Stem Cell Niche inArabidopsis
Authors: Chen Min , Liu Huili , Kong Jixiang , Yang Yali , Zhang Naichao , Li Ruijing , Yue Jianbin , Huang Jiaqing , Li Chuanyou , Cheung Alice Y. , Tao Li-zhen
Published: August 2011

The root stem cell niche defines the area that specifies and maintains the stem cells and is essential for the maintenance of root growth. Here, we characterize and examine the functional role of a quiescent center (QC)–expressed RAC/ROP GTPase activator, RopGEF7, in Arabidopsis thaliana. We show that RopGEF7 interacts with At RAC1 and overexpression of a C-terminally truncated constitutively active RopGEF7 (RopGEF7ΔC) activates RAC/ROP GTPases. Knockdown of RopGEF7 by RNA interference causes defects in embryo patterning and maintenance of the QC and leads to postembryonic loss of root stem cell population. Gene expression studies indicate that RopGEF7 is required for root meristem maintenance as it regulates the expression of PLETHORA1 (PLT1) and PLT2, which are key transcription factors that mediate the patterning of the root stem cell niche. Genetic analyses show that RopGEF7 interacts with PLT genes to regulate QC maintenance. Moreover, RopGEF7 is induced transcriptionally by auxin while its function is required for the expression of the auxin efflux protein PIN1 and maintenance of normal auxin maxima in embryos and seedling roots. These results suggest that RopGEF7 may integrate auxin-derived positional information in a feed-forward mechanism, regulating PLT transcription factors and thereby controlling the maintenance of root stem cell niches.
African elephant age determination from teeth: validation from known individuals
Authors: Lee Phyllis C. , Sayialel Soila , Lindsay W. Keith , Moss Cynthia J.
Published: August 2011

We assess tooth‐based age criteria for African elephants developed by Laws in relation to known‐aged individuals in the Amboseli elephant population. Laws’s technique remains a robust and useful mechanism for age determination, although we suggest revisions to the oldest age categories. Blind age assignment to jaws of unknown sex using the Laws criteria resulted in misclassification of M4 and M5; measures overlapped too much to differentiate these teeth by sex. Sexes could be reliably distinguished after age 30 or XIX in tooth category by two measures: mandible thickness and width of the ascending ramus, but individuals of the same known age differed in tooth wear and progression rates. Such variation needs to be incorporated in the error assigned to tooth age categories. Ages at death of found jaws (n = 266) were similar to results of survival analysis from all demographic data (n = 2455), excluding calves whose jaws decompose because of weathering and scavengers. Jaw‐based models of age at death need correction for the inability to detect this early mortality, which artificially extends mean longevity by up to 6 years.
Therapeutic drug monitoring of antimicrobials
Authors: Roberts Jason A. , Norris Ross , Paterson David L. , Martin Jennifer H.
Published: August 2011

Optimizing the prescription of antimicrobials is required to improve clinical outcome from infections and to reduce the development of antimicrobial resistance. One such method to improve antimicrobial dosing in individual patients is through application of therapeutic drug monitoring (TDM). The aim of this manuscript is to review the place of TDM in the dosing of antimicrobial agents, specifically the importance of pharmacokinetics (PK) and pharmacodynamics (PD) to define the antimicrobial exposures necessary for maximizing killing or inhibition of bacterial growth. In this context, there are robust data for some antimicrobials, including the ratio of a PK parameter (e.g. peak concentration) to the minimal inhibitory concentration of the bacteria associated with maximal antimicrobial effect. Blood sampling of an individual patient can then further define the relevant PK parameter value in that patient and, if necessary, antimicrobial dosing can be adjusted to enable achievement of the target PK/PD ratio. To date, the clinical outcome benefits of a systematic TDM programme for antimicrobials have only been demonstrated for aminoglycosides, although the decreasing susceptibility of bacteria to available antimicrobials and the increasing costs of pharmaceuticals, as well as emerging data on pharmacokinetic variability, suggest that benefits are likely.
Internationally adopted children in Finland: parental evaluations of symptoms of reactive attachment disorder and learning difficulties – FINADO study
Authors: Raaska H. , Elovainio M. , Sinkkonen J. , Matomäki J. , Mäkipää S. , Lapinleimu H.
Published: August 2011

Objective  This study investigated the association between psychological symptoms, such as features of reactive attachment disorder (RAD), and learning difficulties among international adoptees in Finland.

Methods  The data for this study came from the FINnish ADOption (FINADO) study covering all internationally adopted children in Finland (n= 1450), with a response rate of 55.7%. The subsample consisted of 395 adopted children aged 9–15 (51.6% girls, 48.4% boys). Learning difficulties were evaluated by a screening questionnaire ‘Five To Fifteen’ and symptoms of RAD by FINADO RAD scale.

Results  The parents estimated that one‐third (33.4%) of the internationally adopted children had some, and 12.7% had severe learning difficulties, i.e. three and six times more than in normal population, respectively. RAD symptoms at the time of adoption were associated with learning difficulties at school age (OR 4.57, 95% CI 2.57–8.13).

Conclusions  Learning difficulties are common among internationally adopted children in Finland and symptoms of RAD are associated with a child's learning difficulties.
Translational Mini-Review Series on B cell subsets in disease. Transitional B cells in systemic lupus erythematosus and Sjögren's syndrome: clinical implications and effects of B cell-targeted therapies
Authors: Vossenkämper A , Lutalo P M K , Spencer J
Published: August 2011

OTHER ARTICLES PUBLISHED IN THIS MINI-REVIEW SERIES ON B CELL SUBSETS IN DISEASE

B cells in multiple sclerosis: drivers of disease pathogenesis and Trojan horse for Epstein—Barr virus entry to the central nervous system? Clinical and Experimental Immunology 2012, 167: 1–6. Reconstitution after haematopoietic stem cell transplantation – revelation of B cell developmental pathways and lineage phenotypes. Clinical and Experimental Immunology 2012, 167: 15–25.

Systemic lupus erythematosus (SLE) and Sjögren's syndrome are autoimmune disorders which are characterized by a disturbed B cell homeostasis which leads ultimately to dysfunction of various organs. One of the B cell subsets that appear in abnormal numbers is the population of transitional B cells, which is increased in the blood of patients with SLE and Sjögren's syndrome. Transitional B cells are newly formed B cells. In mice, transitional B cells undergo selection checks for unwanted specificity in the bone marrow and the spleen in order to eliminate autoreactive B cells from the circulating naive B cell population. In humans, the exact anatomical compartments and mechanisms of the specificity check-points for transitional B cells remain unclear, but appear to be defective in SLE and Sjögren's syndrome. This review aims to highlight the current understanding of transitional B cells and their defects in the two disorders before and after B cell-targeted therapies.
Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease
Authors: Tang Y , Bian Z , Zhao L , Liu Y , Liang S , Wang Q , Han X , Peng Y , Chen X , Shen L , Qiu D , Li Z , Ma X
Published: August 2011

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (Tregs) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose Treg-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17+ cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and Tregs should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.
Synergistic effects of seasonal rainfall, parasites and demography on fluctuations in springbok body condition
Authors: Turner Wendy C. , Versfeld Wilferd D. , Kilian J. Werner , Getz Wayne M.
Published: August 2011

1. Seasonality of rainfall can exert a strong influence on animal condition and on host–parasite interactions. The body condition of ruminants fluctuates seasonally in response to changes in energy requirements, foraging patterns and resource availability, and seasonal variation in parasite infections may further alter ruminant body condition.

2. This study disentangles the effects of rainfall and gastrointestinal parasite infections on springbok (Antidorcas marsupialis) body condition and determines how these factors vary among demographic groups.

3. Using data from four years and three study areas, we investigated (i) the influence of rainfall variation, demographic factors and parasite interactions on parasite prevalence or infection intensity, (ii) whether parasitism or rainfall is a more important predictor of springbok body condition and (iii) how parasitism and condition vary among study areas along a rainfall gradient.

4. We found that increased parasite intensity is associated with reduced body condition only for adult females. For all other demographic groups, body condition was significantly related to prior rainfall and not to parasitism. Rainfall lagged by two months had a positive effect on body condition.

5. Adult females showed evidence of a ‘periparturient rise’ in parasite intensity and had higher parasite intensity and lower body condition than adult males after parturition and during early lactation. After juveniles were weaned, adult females had lower parasite intensity than adult males. Sex differences in parasitism and condition may be due to differences between adult females and males in the seasonal timing of reproductive effort and its effects on host immunity, as well as documented sex differences in vulnerability to predation.

6. Our results highlight that parasites and the environment can synergistically affect host populations, but that these interactions might be masked by their interwoven relationships, their differential impacts on demographic groups, and the different time‐scales at which they operate.
Some like it toxic
Authors: CORRADI NICOLAS , CHAREST CHRISTIANE
Published: August 2011

Humans are notorious for disturbing terrestrial ecosystems worldwide, especially those that are in close proximity to urban areas. This disturbance has involved the accumulation of various types of chemical pollutants, of either agricultural or industrial origins, in both soil and water ecosystems. Pollutants have sometimes included essential plant nutrients, such as phosphate and nitrate, which have piled up throughout the years in many ecosystems as a consequence of aggressive agricultural practices, and a number of toxic or trace metals, e.g. iron, nickel or zinc that are important at low levels for the fitness of living organisms, but otherwise toxic at high concentrations (Ker & Charest 2010; Audet & Charest 2008). In order to reduce the load of toxic elements, scientists have used the natural capacity of several plant species to sequestrate them from the soil and, ultimately, render them harmless. This process, called phytoremediation, is rather slow, as most plants take years to build up their biomass but has been shown to be ‘boostable’ under experimental conditions in the presence of a particular group of plant symbionts in the soil – the arbuscular mycorrhizal fungi (AMF) (Gohre & Paszkowski 2006). These latter organisms are now widely recognized as being very beneficial for purposes of phytoremediation, but their biodiversity in the most disturbed ecosystems is still virtually unknown. Are these fungi really abundant in heavily polluted soils, or are their communities shrunken down like those of other microorganisms in the presence of heavy pollution? In this issue of Molecular Ecology, the study by Hassan et al. (2011) provides answers to these specific questions by determining the extent of AMF biodiversity across several urbanized areas in the City of Montréal.
Development of pharyngo‐esophageal physiology during swallowing in the preterm infant
Authors: Rommel N. , van Wijk M. , Boets B. , Hebbard G. , Haslam R. , Davidson G. , Omari T.
Published: August 2011

Background  Poor feeding is a common cause of prolonged hospitalization of preterm infants. Pharyngeal and upper esophageal sphincter (UES) function of preterm infants has been technically difficult to assess and is therefore poorly characterized. The aim of this study was to assess the development of pharyngeal motility, UES function, and their coordination during nutritive swallowing in preterm infants.

Methods  Development of swallowing was assessed in 18 preterm infants. High resolution manometry was performed at first oral feeding attempt (31–32 week) and then weekly for 4 weeks. Pharyngeal and UES pressure changes were characterized in 980 swallows.

Key Results  During swallowing, we observed an age‐related increase in peak pharyngeal pressure at the laryngeal inlet (1 cm above UES) but an age‐related decrease in the time required for the UES to fully relax to nadir. Analysis of the timing of proximal pharyngeal contractile peak and UES nadir showed that the UES was not fully relaxed when bolus propulsive forces were at their peak in the youngest infants.

Conclusions & Inferences  Results show developmental changes in infant swallow physiology that can be clearly linked to the effectiveness of nutritive swallowing. Most preterm infants demonstrated poor pharyngeal pressures at the laryngeal inlet coupled with poor coordination of pharyngeal propulsion with UES relaxation. These pressure patterns were less efficient than those demonstrated by older infants who were more adept at feeding. These observations may explain why infants under 34 weeks are physiologically unable to feed effectively and experience frequent choking and fatigue during feeding.
A cellular expression map of the Arabidopsis AUXIN RESPONSE FACTOR gene family
Authors: Rademacher Eike H. , Möller Barbara , Lokerse Annemarie S. , Llavata‐Peris Cristina I. , van den Berg Willy , Weijers Dolf
Published: August 2011

The plant hormone auxin triggers a wide range of developmental and growth responses throughout a plant’s life. Most well‐known auxin responses involve changes in gene expression that are mediated by a short pathway involving an auxin‐receptor/ubiquitin‐ligase, DNA‐binding auxin response factor (ARF) transcription factors and their interacting auxin/indole‐3‐acetic acid (Aux/IAA) transcriptional inhibitors. Auxin promotes the degradation of Aux/IAA proteins through the auxin receptor and hence releases the inhibition of ARF transcription factors. Although this generic mechanism is now well understood, it is still unclear how developmental specificity is generated and how individual gene family members of response components contribute to local auxin responses. We have established a collection of transcriptional reporters for the ARF gene family and used these to generate a map of expression during embryogenesis and in the primary root meristem. Our results demonstrate that transcriptional regulation of ARF genes generates a complex pattern of overlapping activities. Genetic analysis shows that functions of co‐expressed ARFs converge on the same biological processes, but can act either antagonistically or synergistically. Importantly, the existence of an ‘ARF pre‐pattern’ could explain how cell‐type‐specific auxin responses are generated. Furthermore, this resource can now be used to probe the functions of ARF in other auxin‐dependent processes.
Arabidopsis thaliana GEX1 has dual functions in gametophyte development and early embryogenesis
Authors: Alandete‐Saez Monica , Ron Mily , Leiboff Samuel , McCormick Sheila
Published: August 2011

GEX1 is a plasma membrane protein that is conserved among plant species, and has previously been shown to be expressed in sperm cells and some sporophytic tissues. Here we show that GEX1 is also expressed in the embryo sac before cellularization, in the egg cell after cellularization, in the zygote/embryo immediately after fertilization and in the pollen vegetative cell. We functionally characterize GEX1 in Arabidopsis thaliana, and show that it is a versatile protein that performs functions during male and female gametophyte development, and during early embryogenesis. gex1‐1/+ plants, which synthesize a truncated GEX1 mRNA encoding a protein lacking the predicted cytoplasmic domain, but still targeted to the plasma membrane, had embryos that arrested before the pre‐globular stage. gex1‐3/+ plants, carrying a null GEX1 allele, had defects during male and female gametophyte development, and during early embryogenesis. Using an antisense GEX1 transgenic line we demonstrate that the predicted GEX1 extracellular domain is sufficient and necessary for GEX1 function during the development of both gametophytes. The predicted cytoplasmic domain is necessary for correct early embryogenesis and mediates homodimer formation at the plasma membrane. We propose that dimerization of GEX1 in the zygote might be an upstream step in a signaling cascade regulating early embryogenesis.
Evaluation of process‐oriented supervision of student nurses: A Swedish case study
Authors: Lindquist Ingegerd , Johansson Ingrid , Severinsson Elisabeth
Published: August 2011

The value of supervision that is provided to student nurses during their education is high. The aim of this study was to evaluate the organizational changes in an educational program for Swedish student nurses, focusing on the content and quality of process‐oriented supervision. The research question was: Do the organizational changes pertaining to the student nurses' supervision (its reduced frequency and mandatory nature) influence its content and quality and, if so, in which ways? The data were collected by focus group discussions and were analyzed by a qualitative content analysis. Three themes emerged: difficulties with the new organization, the content and learning outcomes of supervision, and the nurse supervisors' intentions. Supervision is recommended in order to achieve the goal of nursing education and to ensure that student nurses gain an understanding of their experiences, thus equipping them with the professional skills and competence that are required to meet patients' needs.
Piscivory and diet overlap between two non‐native fishes in southern Chilean streams
Authors: ARISMENDI IVAN , GONZÁLEZ JORGE , SOTO DORIS , PENALUNA BROOKE
Published: August 2011

Trophic relations among introduced species may induce highly variable and complex effects in communities and ecosystems. However, studies that identify the potential impacts for invaded systems and illuminate mechanisms of coexistence with native species are scarce. Here, we examined trophic relations between two introduced fishes in streams of NW Patagonia, rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta). These species originate from different regions of the Northern Hemisphere but they now coexist as invading species over the world. We used gastric contents and stable isotopes analysis to compare the diets of two size‐classes of these two invaders in three localities of southern Chile. Both species displayed similar ontogenic diet shifts with smaller trout consuming mostly invertebrates and larger trout being more piscivorous and epibenthic feeders. However, piscivory was more prevalent in brown trout than in rainbow trout and highest at the site with the greatest density of native fishes suggesting that the availability of native fishes as trout prey may limit the occurrence of trout piscivory. We found an elevated dietary overlap between the two trout species at larger sizes while at smaller size a higher intraspecific dietary overlap occurred suggesting a potential interference competition among the two fish invaders especially at larger sizes. Our results highlight that the impacts of invading species on non‐native fishes are context specific (i.e. species and ontogenic stages) and thus, difficult to generalize.
Alpha‐fetoprotein producing ovarian clear cell carcinoma with a neometaplasia to hepatoid carcinoma arising from endometriosis: A case report
Authors: Takahashi Yoshiki , Mogami Haruta , Hamada Shinshichi , Urasaki Koji , Konishi Ikuo
Published: August 2011

We present a rare case of alpha‐fetoprotein (AFP) producing ovarian clear cell carcinoma. This is the first report of a clear cell ovarian carcinoma with hepatoid carcinoma arising from endometriosis. A 54‐year‐old menopausal woman had a primary ovarian carcinoma of International Federation of Gynecology and Obstetrics stage IIIc. Serum level of AFP was 4195 ng/mL. Histological examination revealed clear cell adenocarcinoma arising from endometriosis with hepatoid carcinoma. Metastatic liver and lymph node tumors were found after 25 months from the first surgery. However, the patient's serum AFP was within normal limits. The recurrent and metastatic tumors disappeared in response to combined liposomal doxorubicin and carboplatin chemotherapy. She has had a disease‐free survival of 4 years. In conclusion, the patient had a clear cell ovarian carcinoma with hepatoid carcinoma arising clearly from endometriosis. The recurrent tumors did not show a component of hepatoid carcinoma. Therefore, it is possible to expect better survival with good sensitivity to chemotherapy.
Balloon tamponade during cesarean section is useful for severe post‐partum hemorrhage due to placenta previa
Authors: Ishii Takako , Sawada Kenjiro , Koyama Shunsuke , Isobe Aki , Wakabayashi Atsuko , Takiuchi Tsuyoshi , Kanagawa Takeshi , Tomimatsu Takuji , Ogita Kazuhide , Kimura Tadashi
Published: August 2011

Aim:  Severe post‐partum hemorrhage during cesarean section due to placenta previa is still one of the leading causes of maternal mortality. The aim of this study was to evaluate the efficiency of intrauterine tamponade with a Sengstaken‐Blakemore tube (SB‐tube) for the treatment of severe post‐partum hemorrhage in cases of placenta previa.

Material and Methods:  Data were collected from our departmental clinical records on all patients who underwent caesarian section due to placenta previa between 2007 and 2009.

Results:  During the period analyzed, 37 patients underwent caesarian section due to placenta previa/low‐lying placenta. Four (11%) underwent hysterectomy due to placenta accreta and 33 (89%) were treated conservatively. Of the 33 patients with conserved uterus, 10 (28%) patients required a SB‐tube during the cesarean section because of continuous post‐partum hemorrhage despite appropriate medical treatment. The median bleeding during the operation was 2030 ± 860 mL in the patients who used SB‐tube. None of them presented severe complications related to these procedures or required any further invasive surgery.

Conclusion:  Intrauterine balloon‐tamponade could successfully control severe hemorrhage from a lower uterine segment of a patient with placenta previa. This technique is simple to use, scarcely invasive, and available at a low cost to all maternity wards, and should be considered as one of the first management options to reduce the risk of undesirable hysterectomy.
Immunohistochemical distribution of toll‐like receptor 4 in preterm human fetal membrane
Authors: Choi Seong Jin , Jung Soon‐Hee , Eom Minseob , Han Kyoung Hee , Chung In‐Bai , Kim Soo‐Ki
Published: August 2011

Aim:  Toll‐like receptor 4 (TLR‐4) is the major receptor used for recognition of specific gram negative bacteria by the host immune system. The role of TLR‐4 has been revealed in preterm parturition. This study aims to demonstrate the immunohistochemical expression of TLR‐4 with regard to histological layers and anatomical regions of the human fetal membranes.

Material and Methods:  Fetal membranes were obtained from the uterine fundus and low segment. Immunohistochemical staining for TLR‐4 and hematoxylin and eosin stain were performed.

Results:  The chorion expressed significantly higher levels of TLR‐4 than the amnion (P = 0.001). There was no difference in the expression of TLR‐4 between the uterine fundus and the uterine low segment (P = 0.942). There was no significant difference in TLR‐4 expression according to the presence of histological chorioamnionitis (P = 0.444). TLR‐4 expression decreased significantly with the progression of gestation (P = 0.002).

Conclusions:  The level of expression of TLR‐4 did not differ according to anatomic location, but did differ according to the histological layer of the human fetal membranes and gestational age. These results suggest that TLR‐4 may be involved in preterm parturition.
Comparison of success rates of ‘transvaginal aspiration and tetracycline sclerotherapy’ versus ‘only aspiration’ in the management of non‐neoplastic ovarian cysts
Authors: Kars Bulent , Buyukbayrak Esra E. , Karsidag A. Yasemin K. , Pirimoglu Meltem , Unal Orhan , Turan Cem
Published: August 2011

Aim:  To investigate the value of tetracycline sclerotherapy for management of recurrent or persisting non‐neoplastic ovarian cysts in comparison to the aspiration without sclerotherapy.

Material and Methods:  Ninety‐six patients with proven non‐neoplastic ovarian cysts were randomized into two groups. Group 1 patients underwent cyst aspiration together with tetracycline sclerotherapy (n = 48). Group 2 patients underwent only cyst aspiration without tetracycline sclerotherapy (n = 48). Then, all patients were followed up monthly with ultrasonography for 12 months. The procedure was considered to have failed if the recurring cyst, detected by ultrasound, was 4 cm in size or greater.

Results:  There were no differences between the two groups regarding demographic data, initial cyst volume and tumor markers. Recurrence rates within 12 months were 14.6% in group 1 and 50% in group 2 (P < 0.001).

Conclusion:  Based on the recurrence rates, we suggest transvaginal aspiration together with tetracycline sclerotherapy rather than only simple transvaginal aspiration in the management of non‐neoplastic ovarian cysts.
Exploiting the antioxidant potential of a common vitamin: Could vitamin C prevent postmenopausal osteoporosis?
Authors: Talaulikar Vikram Sinai , Chambers Timothy , Manyonda Isaac
Published: August 2011

Aim:  Oxidative stress is thought to play a central role in the pathophysiology of various conditions affecting women's health, including cancer, preeclampsia and osteoporosis. On the back of animal experimentation, we sought to establish whether the oral administration of vitamin C at high doses to postmenopausal women would achieve the plasma antioxidant activity that could prevent osteoporosis.

Methods:  In our pilot study, we administered vitamin C at a dose of 10 grams daily to eight healthy postmenopausal women over a period of four weeks and measured their serum levels of vitamin C and crosslaps (markers of bone turnover) at baseline and then on a weekly basis.

Results:  We found an initial rise in the plasma levels of vitamin C, but these rapidly fell over four weeks and could not be sustained despite continued therapy, presumably due to limited absorption and possibly even augmented excretion. We found no discernable change in the serum levels of crosslaps in association with the consumption of high doses of vitamin C.

Conclusion:  Although vitamin C has antioxidant properties, when given orally, even at a high dose, the serum levels required for it to exhibit antioxidant activity cannot be attained. This approach holds no potential for the use of vitamin C in the prevention of osteoporosis, although other routes of administration could overcome this.
Promptness of diagnosis is the main prognostic factor after colonoscopic perforation
Authors: La Torre M. , Velluti F. , Giuliani G. , Di Giulio E. , Ziparo V. , La Torre F.
Published: August 2011

Aim  The authors present their experience of colonoscopic perforation and its management, with an analysis of factors affecting outcome.

Method  During the last 10 years, 22 cases of colonoscopic perforation (CP) were identified in two different institutions. Multiple logistic regression analysis was used to identify significant predictors of morbidity and mortality.

Results  Morbidity and mortality rates were 31% and 13.6%, respectively. Prompt diagnosis was the most powerful predictor of outcome of CP. Multiple logistic regression analysis showed that morbidity and mortality were significantly related to a delay in diagnosis of more than 24 h (P = 0.03 and P = 0.04).

Conclusion  The results emphasize the importance of prompt assessment of a patient who develops symptoms after colonoscopy.