bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic energy distribution of multiply charged ions in Coulomb explosion of Xe clusters
Authors: Heidenreich Andreas , Jortner Joshua
Published: February 2011

We report on the calculations of kinetic energy distribution (KED) functions of multiply charged, high-energy ions in Coulomb explosion (CE) of an assembly of elemental Xen clusters (average size 〈n〉 = 200–2171) driven by ultra-intense, near-infrared, Gaussian laser fields (peak intensities 1015 – 4 × 1016 W cm−2, pulse lengths 65–230 fs). In this cluster size and pulse parameter domain, outer ionization is incomplete/vertical, incomplete/nonvertical, or complete/nonvertical, with CE occurring in the presence of nanoplasma electrons. The KEDs were obtained from double averaging of single-trajectory molecular dynamics simulation ion kinetic energies. The KEDs were doubly averaged over a log-normal cluster size distribution and over the laser intensity distribution of a spatial Gaussian beam, which constitutes either a two-dimensional (2D) or a three-dimensional (3D) profile, with the 3D profile (when the cluster beam radius is larger than the Rayleigh length) usually being experimentally realized. The general features of the doubly averaged KEDs manifest the smearing out of the structure corresponding to the distribution of ion charges, a marked increase of the KEDs at very low energies due to the contribution from the persistent nanoplasma, a distortion of the KEDs and of the average energies toward lower energy values, and the appearance of long low-intensity high-energy tails caused by the admixture of contributions from large clusters by size averaging. The doubly averaged simulation results account reasonably well (within 30%) for the experimental data for the cluster-size dependence of the CE energetics and for its dependence on the laser pulse parameters, as well as for the anisotropy in the angular distribution of the energies of the Xeq+ ions. Possible applications of this computational study include a control of the ion kinetic energies by the choice of the laser intensity profile (2D/3D) in the laser-cluster interaction volume.
Structural properties and phase transitions in a silica clathrate
Authors: Liang Yunfeng , Ogundare Folorunso O. , Miranda Caetano R. , Christie Jamieson K. , Scandolo Sandro
Published: February 2011

Melanophlogite, a low-pressure silica polymorph, has been extensively studied at different temperatures and pressures by molecular dynamics simulations. While the high-temperature form is confirmed as cubic, the low-temperature phase is found to be slightly distorted, in agreement with experiments. With increasing pressure, the crystalline character is gradually lost. At 8 GPa, the radial distribution function is consistent with an amorphous state. Like pristine glass, the topology changes, plastic behavior, and permanent densification appear above ∼12 GPa, triggered by Si coordination number changes. We predict that a partial crystalline and amorphous sample can be obtained by recovering the sample from a pressure of ∼12–16 GPa.
The effect of substitution of Fe with Cr on the giant magnetoresistance of current-perpendicular-to-plane spin valves with Co2FeSi Heusler alloy
Authors: Goripati, H. S. , Furubayashi, T. , Karthik, S. V. , Nakatani T. M. , Takahashi, Y. K. , Hono, K.
Published: February 2011

We fabricated current-perpendicular-to-plane spin valves (SV) using Co2FeSi and Co2(Cr0.1Fe0.9)Si Heusler alloys as ferromagnetic layers and a Ag spacer. The SV with Co2(Cr0.1Fe0.9)Si showed relatively large magnetoresistance (MR) ratio of 11.9 % and the resistance change-area product (ΔRA) of 6.3 mΩ μm2 at room temperature as compared to the MR ratio of 9.4% and the ΔRA value of 4.1 mΩ μm2 for the SV using Co2FeSi. This indicates that the spin polarization of Co2FeSi is enhanced by the substitution of Cr for Fe as suggested by a previous point contact Andreev reflection measurements. Considering the high Curie temperature of 993 K, the Co2(Cr0.1Fe0.9)Si alloy could be promising material for spin polarized electron source.
Note: Interpolation for evaluation of a two-dimensional spatial profile of plasma densities at low gas pressures
Authors: Oh Se-Jin , Kim Young-Chul , Chung Chin-Wook
Published: February 2011

An interpolation algorithm for the evaluation of the spatial profile of plasma densities in a cylindrical reactor was developed for low gas pressures. The algorithm is based on a collisionless two-dimensional fluid model. Contrary to the collisional case, i.e., diffusion fluid model, the fitting algorithm depends on the aspect ratio of the cylindrical reactor. The spatial density profile of the collisionless fitting algorithm is presented in two-dimensional images and compared with the results of the diffusion fluid model.
Half metallicity and electronic structures in armchair BCN-hybrid nanoribbons
Authors: Liu Z. M. , Zhu Y. , Yang Z. Q.
Published: February 2011

We study magnetism and electronic structures of armchair BCN-hybrid nanoribbons from density functional theory. Different from armchair graphene nanoribbons, armchair BCN-hybrid nanoribbons are found to present magnetism along the edges of the nanoribbons if B and N atoms are unpaired in the nanoribbons. Intriguing spin-polarized bands, including magnetic semiconductors, half metals, and magnetic metals, are obtained in the armchair nanoribbons with both the edges composed of C and N atoms. The spin polarization in these armchair nanoribbons is ascribed to the appearance of the unsaturated electronic states in the systems. The magnetic metallicity can be tuned further to half metallicity by adsorbing O atoms at appropriate positions in the ribbons. The electronic structures of the nanoribbons without spin polarization are also analyzed. Our studies provide understanding of the magnetism mechanisms and the electronic properties and most importantly, how to achieve half metallicity in low-dimensional BCN-hybrid systems.
Magnetic hyperfine coupling of a methyl group undergoing internal rotation: A case study of methyl formate
Authors: Tudorie M. , Coudert L. H. , Huet T. R. , Jegouso D. , Sedes G.
Published: February 2011

The hyperfine structure of methyl formate was recorded in the 2–20 GHz range. A molecular beam coupled to a Fourier transform microwave spectrometer having an instrumental resolution of 0.46 kHz and limited by a Doppler width of a few kHz was used. A-type lines were found split by the magnetic hyperfine coupling while no splittings were observed for E-type lines. Symmetry considerations were used to account for the internal rotation of the methyl top and to derive effective hyperfine coupling Hamiltonians. Neglecting the spin–rotation magnetic coupling, the vanishing splittings of the E-type lines could be understood and analyses of the hyperfine patterns of the A-type lines were performed. The results are consistent with a hyperfine structure dominated by the magnetic spin–spin coupling due to the three hydrogen atoms of the methyl group.
Combined effect of viscosity and vorticity on single mode Rayleigh–Taylor instability bubble growth
Authors: Banerjee Rahul , Mandal Labakanta , Roy S. , Khan M. , Gupta M. R.
Published: February 2011

The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh–Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it.
An ultrasensitive and low-cost graphene sensor based on layer-by-layer nano self-assembly
Authors: Zhang Bo , Cui Tianhong
Published: February 2011

The flexible cancer sensor based on layer-by-layer self-assembled graphene reported in this letter demonstrates features including ultrahigh sensitivity and low cost due to graphene material properties in nature, self-assembly technique, and polyethylene terephthalate substrate. According to the conductance change of self-assembled graphene, the label free and labeled graphene sensors are capable of detecting very low concentrations of prostate specific antigen down to 4 fg/ml (0.11 fM) and 0.4 pg/ml (11 fM), respectively, which are three orders of magnitude lower than carbon nanotube sensors under the same conditions of design, manufacture, and measurement.
Nonlinear dielectric properties of (Bi0.5Na0.5)TiO3-based lead-free piezoelectric thick films
Authors: Zhang Haibo , Jiang Shenglin , Kajiyoshi Koji
Published: February 2011

The effects of applied dc bias field, temperature, frequency, and doping types on the nonlinear dielectric behaviors of Bi0.5(Na0.82K0.18)0.5TiO3 piezoelectric films with thickness of 40 μm have been investigated. It is demonstrated that the dielectric permittivity versus ac field amplitude departed from linearity at high temperature, which is caused by a decrease of the coercive field with increasing temperature. The frequency dependence of the dielectric permittivity is related to domain wall pinning. The thicker piezoelectric films exhibit higher extrinsic contribution due to high domain wall mobility and less domain wall pinning, resulting from the increased grain size and film thickness.
Connectionism and the role of morphology in visual word recognition
Authors: Rueckl Jay
Published: February 2011

This paper provides a review of the connectionist perspective on the role of morphology in visual word recognition. Several computational models of morphological effects in reading are described and relationships between these models, models of past tense production, and models of other aspects of word recognition are traced. Limitations of extant models are noted, as are some of the technical challenges that must be solved to develop the next generation of models. Finally, some directions for future research are identified.
Nanoscale physical microstructure and micromagnetic behaviour of CoIr film with negative anisotropy
Authors: Ngo D-T , Hashimoto A , McVitie S , Saito S , Chapman J N , Takahashi M
Published: February 2011

The physical and magnetic structure of hcp-CoIr(10 nm)/Ru(5 nm) has been systematically characterized using transmission electron microscopy. The film was observed to be polycrystalline with a mean grain size of 15.7 ± 1.1 nm. Additionally, diffraction analysis in the TEM confirmed the presence of a [0 0 0 1] texture normal to the film plane resulting from a Ru seed layer. Lorentz microscopy observation with in situ magnetizing experiments showed that the film possessed a weak-anisotropy easy axis with considerable dispersion of magnetic ripple and domain wall nucleation over a negative field of 25 Oe. Magnetization reversal on the hard axis shows a non-coherent rotation of magnetic moments from easy axis to hard axis denoted by a non-uniform nucleation of low-angle walls. Dispersion of magnetization ripple is in agreement with classical ripple theory. Generally the magnetization reversal was complete by 30 Oe; however, some small regions remained which were not fully reversed with associated 360° domain walls. These appeared to be strongly pinned locally and required much larger fields to eliminate them.
Role of the uncompensated interface spins in polycrystalline exchange-biased systems
Authors: Geshev J , Dias T , Nicolodi S , Cichelero R , Harres A , Acuña J J S , Pereira L G , Schmidt J E , Deranlot C , Petroff F
Published: February 2011

This work reports on the evolution of the exchange-bias (EB) field and the shape of the magnetization curves with the thickness of the non-magnetic spacer layer (SL, either Cu or Al2O3) of polycrystalline Co/IrMn/SL/Co films as well as their modifications caused by different post-deposition annealing treatments. Conventional x-ray diffractometry, small-angle x-ray reflectivity and cross-section transmission electron microscopy were used for the structural characterization. The hysteresis loops traced on the as-made films without SL present a pattern of two oppositely displaced subloops; it was observed that the positively shifted subloop gradually vanishes with the increase in the SL thickness. Our study points out that the significant decrease in the EB field of the top-pinned Co layers after magnetic annealing could be attributed to relaxation of the bottom interfacial IrMn spin structure caused by the heating. This relaxation mechanism might be considered as an alternative to the commonly accepted IrMn and Co interdiffusion and defect creation at the interface. Models for the uncompensated spins' configurations at each of the ferromagnet (FM)/antiferromagnet (AF) and AF/FM interfaces are proposed in order to explain the modifications of the magnetic behaviour with the SL thickness and with the annealing.
Representing pointsets as unions of Borel sets
Authors: Becker Howard
Published: February 2011

We consider a method of representing projective sets by a particular type of union of Borel sets, assuming AD.
libfbi: a C++ implementation for fast box intersection and application to sparse mass spectrometry data
Authors: Kirchner Marc , Xu Buote , Steen Hanno , Steen Judith A. J.
Published: February 2011

Motivation: Algorithms for sparse data require fast search and subset selection capabilities for the determination of point neighborhoods. A natural data representation for such cases are space partitioning data structures. However, the associated range queries assume noise-free observations and cannot take into account observation-specific uncertainty estimates that are present in e.g. modern mass spectrometry data. In order to accommodate the inhomogeneous noise characteristics of sparse real-world datasets, point queries need to be reformulated in terms of box intersection queries, where box sizes correspond to uncertainty regions for each observation.

Results: This contribution introduces libfbi, a standard C++, header-only template implementation for fast box intersection in an arbitrary number of dimensions, with arbitrary data types in each dimension. The implementation is applied to a data aggregation task on state-of-the-art liquid chromatography/mass spectrometry data, where it shows excellent run time properties.

Availability: The library is available under an MIT license and can be downloaded from http://software.steenlab.org/libfbi.

Contact:  marc.kirchner@childrens.harvard.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Metalloprotease production by Paenibacillus larvae during the infection of honeybee larvae
Authors: Antúnez Karina , Arredondo Daniela , Anido Matilde , Zunino Pablo
Published: February 2011

American foulbrood is a bacterial disease of worldwide distribution that affects larvae of the honeybee Apis mellifera. The causative agent is the Gram-positive, spore-forming bacterium Paenibacillus larvae. Several authors have proposed that P. larvae secretes metalloproteases that are involved in the larval degradation that occurs after infection. The aim of the present work was to evaluate the production of a metalloprotease by P. larvae during larval infection. First, the complete gene encoding a metalloprotease was identified in the P. larvae genome and its distribution was evaluated by PCR in a collection of P. larvae isolates from different geographical regions. Then, the complete gene was amplified, cloned and overexpressed, and the recombinant metalloprotease was purified and used to generate anti-metalloprotease antibodies. Metalloprotease production was evaluated by immunofluorescence and fluorescence in situ hybridization. The gene encoding a P. larvae metalloprotease was widely distributed in isolates from different geographical origins in Uruguay and Argentina. Metalloprotease was detected inside P. larvae vegetative cells, on the surface of P. larvae spores and secreted to the external growth medium. Its production was also confirmed in vivo, during the infection of honeybee larvae. This protein was able to hydrolyse milk proteins as described for P. larvae, suggesting that could be involved in larval degradation. This work contributes to the knowledge of the pathogenicity mechanisms of a bacterium of great economic significance and is one step in the characterization of potential P. larvae virulence factors.
Repression of the glucose-inducible outer-membrane protein OprB during utilization of aromatic compounds and organic acids in Pseudomonas putida CSV86
Authors: Shrivastava Rahul , Basu Bhakti , Godbole Ashwini , Mathew M. K. , Apte Shree K. , Phale Prashant S.
Published: February 2011

Pseudomonas putidaCSV86 shows preferential utilization of aromatic compounds over glucose. Protein analysis and [14C]glucose-binding studies of the outer membrane fraction of cells grown on different carbon sources revealed a 40 kDa protein that was transcriptionally induced by glucose and repressed by aromatics and succinate. Based on 2D gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis, the 40 kDa protein closely resembled the porin B ofP. putidaKT2440 and carbohydrate-selective porin OprB of variousPseudomonasstrains. The purified native protein (i) was estimated to be a homotrimer of 125 kDa with a subunit molecular mass of 40 kDa, (ii) displayed heat modifiability of electrophoretic mobility, (iii) showed channel conductance of 166 pS in 1 M KCl, (iv) permeated various sugars (mono-, di- and tri-saccharides), organic acids, amino acids and aromatic compounds, and (v) harboured a glucose-specific and saturable binding site with a dissociation constant of 1.3 µM. These results identify the glucose-inducible outer-membrane protein ofP. putidaCSV86 as a carbohydrate-selective protein OprB. Besides modulation of intracellular glucose-metabolizing enzymes and specific glucose-binding periplasmic space protein, the repression of OprB by aromatics and organic acids, even in the presence of glucose, also contributes significantly to the strain’s ability to utilize aromatics and organic acids over glucose.
Color modulates olfactory learning in honeybees by an occasion-setting mechanism
Authors: Mota Theo , Giurfa Martin , Sandoz Jean-Christophe
Published: February 2011

A sophisticated form of nonelemental learning is provided by occasion setting. In this paradigm, animals learn to disambiguate an uncertain conditioned stimulus using alternative stimuli that do not enter into direct association with the unconditioned stimulus. For instance, animals may learn to discriminate odor rewarded from odor nonrewarded trials if these two situations are indicated by different colors that do not themselves become associated with the reward. Despite a growing interest in nonelemental learning in insects, no study has so far attempted to study occasion setting in restrained honeybees, although this would allow direct access to the neural basis of nonelemental learning. Here we asked whether colors can modulate olfactory conditioning of the proboscis extension reflex (PER) via an occasion-setting mechanism. We show that intact, harnessed bees are not capable of learning a direct association between color and sucrose. Despite this incapacity, bees solved an occasion-setting discrimination in which colors set the occasion for appropriate responding to an odor that was rewarded or nonrewarded depending on the color. We therefore provide the first controlled demonstration of bimodal (color–odor) occasion setting in harnessed honeybees, which opens the door for studying the neural basis of such bimodal, nonelemental discriminations in insects.
Hypoxia activates the hedgehog signaling pathway in a ligand‐independent manner by upregulation of Smo transcription in pancreatic cancer
Authors: Onishi Hideya , Kai Masaya , Odate Seiichi , Iwasaki Hironori , Morifuji Yoshihiro , Ogino Toshitatsu , Morisaki Takafumi , Nakashima Yutaka , Katano Mitsuo
Published: February 2011

The hedgehog (Hh) signaling pathway is activated in various types of cancer including pancreatic ductal adenocarcinoma. It has been shown that extremely low oxygen tension (below 1% O2) is found in tumor tissue including pancreatic ductal adenocarcinoma cells (PDAC) and increases the invasiveness of PDAC. To investigate the contribution of the Hh pathway to hypoxia‐induced invasiveness, we examined how hypoxia affects Hh pathway activation and the invasiveness of PDAC. In the present study, three human PDAC lines were cultured under normoxic (20% O2) or hypoxic (1% O2) conditions. Hypoxia upregulated the transcription of Sonic hedgehog (Shh), Smoothened (Smo), Gli1 and matrix metalloproteinase9 (MMP9) and increased the invasiveness of PDAC. Significantly, neither the addition of recombinant Shh (rhShh) nor the silencing of Shh affected the transcription of these genes and the invasiveness of PDAC. On the other hand, silencing of Smo decreased the transcription of Gli1 and MMP9 and PDAC invasiveness. Silencing of Gli1 or MMP9 decreased PDAC invasiveness. These results suggest that hypoxia activates the Hh pathway of PDAC by increasing the transcription of Smo in a ligand‐independent manner and increases PDAC invasiveness. (Cancer Sci 2011; 102: 1144–1150)
Renal dysfunction in patients with thalassaemia
Authors: Quinn Charles T. , Johnson Valerie L. , Kim Hae‐Young , Trachtenberg Felicia , Vogiatzi Maria G. , Kwiatkowski Janet L. , Neufeld Ellis J. , Fung Ellen , Oliveri Nancy , Kirby Melanie , Giardina Patricia J. ,   for the Thalassemia Clinical Research Network
Published: February 2011

Little is known about the effects of thalassaemia on the kidney. Characterization of underlying renal function abnormalities in thalassaemia is timely because the newer iron chelator, deferasirox, can be nephrotoxic. We aimed to determine the prevalence and correlates of renal abnormalities in thalassaemia patients, treated before deferasirox was widely available, using 24‐h collections of urine. We calculated creatinine clearance and urine calcium‐to‐creatinine ratio and measured urinary β2‐microglobulin, albumin, and protein. We used multivariate modelling to identify clinical, therapeutic, and laboratory predictors of renal dysfunction. One‐third of thalassaemia patients who were not regularly transfused had abnormally high creatinine clearance. Regular transfusions were associated with a decrease in clearance (P = 0·004). Almost one‐third of patients with thalassaemia had hypercalciuria, and regular transfusions were associated with an increase in the frequency and degree of hypercalciuria (P < 0·0001). Albuminuria was found in over half of patients, but was not consistently associated with transfusion therapy. In summary, renal hyperfiltration, hypercalciuria, and albuminuria are common in thalassaemia. Higher transfusion intensity is associated with lower creatinine clearance but more frequent hypercalciuria. The transfusion effect needs to be better understood. Awareness of underlying renal dysfunction in thalassaemia can inform decisions now about the use and monitoring of iron chelation.
Immunophenotypic features of acute myeloid leukaemia patients exhibiting high FLT3 expression not associated with mutations
Authors: Riccioni Roberta , Pelosi Elvira , Riti Viviana , Castelli Germana , Lo‐Coco Francesco , Testa Ugo
Published: February 2011

FMS‐related tyrosine kinase 3 (FLT3) mutations are found in 30% of cases of acute myeloid leukaemia (AML). In addition, recent studies have lead to the identification of about 10–15% of AML patients displaying high expression of FLT3, not associated with mutations of the receptor (FLT3 Wild‐type High, FLT3WTH). These AMLs, as well as those displaying internal tandem duplication (ITD) are associated with an unfavourable prognosis. However, the biological features of these AMLs are poorly characterized. The present study explored the immunophenotypic features of FLT3WTH AMLs in 94 de novo cases of AML. The levels of FLT3 expression, as assessed by flow cytometry and FLT3 mutational status, was used to identify four AML subgroups: FLT3WTH (14/94); FLT3 Wild‐type low (FLT3WTL, 48/94); FLT3 internal tandem duplication (FLT3ITD 26/94); FLT3 aspartic acid 835 (FLT3D835, 6/94). FLT3WTH and FLT3ITD were characterized by: high white blast cell counts; predominance of M4 and M5 French‐American‐British classification subtypes and associated expression of myelo‐monocytic markers; high expression of CD123 and TRAIL‐Rs; high expression of receptors for angiogenic growth factors. Addition of FLT3 Ligand to human CD34+ or monocytic cells stimulated CD123 and TRAIL‐R expression. These findings are of potential value for the development of new therapeutic strategies.
Soluble CD163 levels in children with sickle cell disease
Authors: Moller Holger Jon , Nielsen Marianne Jensby , Bartram Jack , Dick Moira C. , Height Susan E. , Moestrup Soren K. , Rees David C.
Published: February 2011

Sickle cell disease (SCD) is characterized by vasculopathy, which has been causally linked to intravascular haemolysis and high levels of free plasma haemoglobin. Soluble CD163 (sCD163) is implicated in the clearance of free plasma haemoglobin and high plasma concentrations have been linked to arterial disease. We therefore investigated the value of sCD163 as a biomarker in children with SCD, and also measured haptoglobin levels in this population. We measured sCD163 in 25 control children with no haemoglobinopathy, 41 with sickle cell anaemia (HbSS) in the steady state, 27 with HbSS taking hydroxycarbamide, and 7 with HbSC disease. There was no significant difference between sCD163 levels in steady‐state HbSS (1·78 mg/l) and controls (1·81 mg/l) (P = 0·86). However, sCD163 levels were significantly lower in those HbSS children taking hydroxycarbamide (1·35 mg/l) compared to both steady state HbSS (P = 0·004) and controls (P = 0·036). In children on hydroxycarbamide, sCD163 correlated negatively and highly significantly with percentage HbF (R = −0·76, P < 0·001), and this relationship was absent in those not taking hydroxycarbamide (R = 0·07, P = 0·65). sCD163 is a potentially useful biomarker in children with SCD, and may have a role in monitoring responses to hydroxycarbamide.
The emergence of angiostrongyliasis in the People’s Republic of China: the interplay between invasive snails, climate change and transmission dynamics
Authors: LV SHAN , ZHANG YI , STEINMANN PETER , YANG GUO‐JING , YANG KUN , ZHOU XIAO‐NONG , UTZINGER JÜRG
Published: February 2011

1. Only few freshwater snail species transmit the rat lungworm Angiostrongylus cantonensis, which is partially explained by the low likelihood of contact between snails and infected rat faeces. The snail Pomacea canaliculata was introduced into China in 1981 and has become the key intermediate host for A. cantonensis. Thus far, the snail has been recorded in 13 provinces of southern China.

2. We developed a biological model and assessed potential impacts of climate change on the distribution of P. canaliculata and hence the transmission of A. cantonensis. Mean January temperature and snail generation intensity (generation number) were identified as the key factors determining P. canaliculata distribution. Our models predict an increase of 56.9% for the ‘spread’ and a decrease of 40.9% for the ‘establishment’ regions (‘spread’ and ‘establishment’ defined according to a national sampling survey) by the 2030s relative to the present day.

3. Key determinants of A. cantonensis transmission were identified as the generation intensity in the intermediate host, the longevity of A. cantonensis‐infected rats and the dormant period of P. canaliculata. Transmission of A. cantonensis occurs only in areas where the snail’s dormant period is <173.2 days. The potential endemic area of A. cantonensis is predicted to double by the 2030s relative to the present day.

4. The tight fit of our model predictions with data derived from a national sampling survey suggests that biological models hold promise for assessing potential impacts of climate change on infectious diseases once key determinants have been established. Geographical variation analysis may offer an approach to identify areas prone to the spread of vectors, intermediate hosts and parasites in a future warmer China and elsewhere.
A survey analysis of grassland dairy farming in Ireland, investigating grassland management, technology adoption and sward renewal
Authors: Creighton P. , Kennedy E. , Shalloo L. , Boland T. M. , O’ Donovan M.
Published: February 2011

The objective of this study was to identify and understand grassland management practices employed on dairy farms in the Republic of Ireland, including grazing‐season length, concentrate‐feed input, uptake of new grassland‐management technologies and frequency and methods of sward renewal. The sample population for the survey was chosen from a proportionate representation of all milk suppliers taken from three of the largest dairy processors in the Republic of Ireland. The sample was subsequently broken down into three stocking rate (SR) and three size categories of milk quota (Qcat) to investigate their effects on the survey variables. Both SR and Qcat had significant effects on the proportion of participants adopting grass‐based technologies and on the amount of supplementary feed offered. Grazing‐season length increased from 228 d in Qcat1 to 249 d in Qcat 3 but was unaffected by SR (241 d; s.d. 3·05). The proportion of the grazing area reseeded annually was significantly affected by SR, increasing from 0·044 to 0·095 of the grassland area as SR increased from SR1 to SR3, with no effect of Qcat (0·068). The results show that on‐farm grass utilization is low, with significant potential for expansion and increased efficiency through increased SRs, greater adoption of grassland‐management technologies and higher levels of sward renewal.
Semen quality and reproductive hormone levels in men from Southern Spain
Authors: Fernandez M. F. , Duran I. , Olea N. , Avivar C. , Vierula M. , Toppari J. , Skakkebæk N. E. , Jørgensen N.
Published: February 2011

In North European countries, a significant difference in semen quality among young men has been shown. Men from the western countries, Denmark, Germany and Norway, have lower semen quality than men from the eastern countries Finland, Estonia and Lithuania. Similarly, men in the western countries have a higher risk of testicular cancer. According to the testicular dysgenesis syndrome (TDS) concept that suggests a link between risk of impaired semen quality and increased risk of testicular cancer, Spanish men would be expected to have a semen quality at a normal level because of their very low testis cancer risk. We therefore investigated 273 men from the Almeria region in the Southern Spain to test this hypothesis. The men delivered semen samples, underwent physical examinations, had a blood sample drawn and provided information on lifestyle and reproductive health parameters. The investigations took place from November 2001 to December 2002. Adjusting for effects of confounders, the median sperm concentration and total sperm count were 62 (95% confidence interval 47–82) million/mL and 206 (153–278) million, respectively. The median numbers of motile and morphologically normal spermatozoa assessed according to strict criteria were 59% (57–62%) and 9.4% (8.6–10.0%), respectively. The median total testosterone and calculated free androgen index were 28 nm (26–30) and 95 (88–103), respectively. Assuming that the investigated men, to a large extent, are representative of the population of young men the Southern Spain, the results show that these have normal semen quality and reproductive hormone levels as expected in a population with a low incidence of testicular cancer.
Teacher Competences required for developing reflection skills of nursing students
Authors: Dekker‐Groen Agaath M. , van der Schaaf Marieke F. , Stokking Karel M.
Published: February 2011

dekker‐groen a.m., van der schaaf m.f. & stokking k.m. (2011) Teacher Competences required for developing reflection skills of nursing students. Journal of Advanced Nursing67(7), 1568–1579.

Aim.  This paper is a report of a study in senior secondary vocational education designed to develop a framework for teacher competences to support nursing students in developing their reflection skills.

Background.  For healthcare‐related professions such as nursing, there is a growing attention for developing reflection skills. Little is known about teacher competences required to support the development of reflection skills in nursing students. Developing a framework of teacher competences can contribute to filling up this gap. These competences are described in 91 indicators distributed over six task domains.

Methods.  A Delphi study was conducted in the first half year of 2008 to get consensus on a framework of teacher competences required for creating the learning environment needed for developing reflection skills in nursing students. Experts judged teacher competences on a seven‐point Likert‐type scale.

Findings.  In the first round, mean scores on the teacher competences were already high. Minor revisions were needed. In the second round, mean scores increased, whereas standard deviations decreased in round 2 compared with round 1. These changes were statistically significant. Coaching was seen as most important task domain.

Conclusion.  Consensus has been reached on teacher competences to be used in nursing education to develop students’ reflection skills. The framework of competences may be a source for curriculum development concerning reflection skills and for teacher training programmes to coach nursing students’ reflections.
Management of perimenstrual symptoms among young Taiwanese nursing students
Authors: Cheng Han‐Fu
Published: February 2011

Aim and objective.  To determine the frequency and distribution of medications used by Taiwanese nursing students for dysmenorrhoea and to investigate potential associations between perimenstrual symptoms and selection of medications.

Background.  Dysmenorrhoea is a symptom‐complex. It is also the leading cause of short‐term school absence and is associated with a negative impact on academic and daily activities. The effectiveness of traditional Chinese medicines and Western medications for ameliorating dysmenorrhoea has been well‐documented. However, no publications were found to examine the selection of traditional Chinese medicines, Western medications or teas among Taiwanese women for the management of dysmenorrhoea and related symptoms.

Design.  A descriptive survey.

Method.  Management of Menstrual Cramps Survey was distributed to a convenience sample of 2758 female nursing students in Southern Taiwan. Content validity and inter‐rater reliability were applied to evaluate the measure. The descriptive statistics and chi‐square comparisons were calculated where appropriate for each of the items of the questionnaires.

Results.  Perimenstrual symptoms were statistically significant indicators for the use of any combination of Western medications, traditional Chinese medicines or teas. Data revealed that there were statistically significant association between perimenstrual symptoms and the uses of traditional Chinese medicines (χ2 = 3·876, df = 1, p = 0·031) or Western medications (χ2 = 10·171, df = 1, p < 0·01).

Conclusions.  Panadol and Si‐Wu‐Tang were the most frequently used medications among Western medicines and traditional Chinese medicines, respectively. However, Western medications were used for a broader spectrum of symptoms than traditional Chinese medicines.

Relevance to clinical practice.  The findings have implications for professional nurses, nurse researchers and society. Nurses teach and promote health, which includes the communication of medication‐related information. To teach young women in Taiwan about the options available for relief of perimenstrual symptoms is significant.
Trends in incidence of hepatocellular carcinoma after diagnosis of hepatitis B or C infection: a population‐based cohort study, 1992–2007
Authors: Thein H.‐H. , Walter S. R. , Gidding H. F. , Amin J. , Law M. G. , George J. , Dore G. J.
Published: February 2011

Summary.  Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the major risk factors for hepatocellular carcinoma (HCC). We examined trends in the incidence of HCC among a population‐based cohort of people infected with HBV or HCV. HBV and HCV cases notified to the New South Wales Health Department between 1992 and 2007 were linked to the Central Cancer Registry, Registry of Births, Deaths and Marriages, and National HIV/AIDS Registries. Crude HCC incidence rates were estimated using person‐time methodology. Age‐standardized incidence rates were calculated using the 2001 Australian population. Trends in incidence were examined using join point regression models. Between 1992 and 2007, 1201 people had a linked HCC record: 556 of those with HBV; 592 with HCV; 45 with HBV/HCV co‐infection; and 8 with HIV co‐infection. The overall age‐standardized HCC incidence rates declined non‐significantly from 148.0 (95% confidence intervals (CI) 63.7, 287.4) per 100 000 population in 1995 to 101.2 (95% CI 67.3, 144.6) in 2007 among the HBV monoinfected group and significantly from 151.8 (95% CI 62.4, 299.8) per 100 000 population to 75.3 (95% CI 50.8, 105.5) among the HCV monoinfected group. However, incidence rates in the HCV monoinfected group progressively increased from the period 1992–1997 to 2004–2007 when adjusted for age, sex, and birth cohort, and the total number of cases per annum continued to increase. Despite declines in the age‐adjusted incidence rates of HCC over time, the absolute number of cases increased likely due to the ageing cohort and an increasing prevalence of both hepatitis B and C in Australia.
Decrease in leaf sucrose synthesis leads to increased leaf starch turnover and decreased RuBP regeneration‐limited photosynthesis but not Rubisco‐limited photosynthesis in Arabidopsis null mutants of SPSA1
Authors: SUN JINDONG , ZHANG JISEN , LARUE CLAYTON T. , HUBER STEVEN C.
Published: February 2011

We investigated the individual effect of null mutations of each of the four sucrose‐phosphate synthase (SPS) genes in Arabidopsis (SPSA1, SPSA2, SPSB and SPSC) on photosynthesis and carbon partitioning. Null mutants spsa1 and spsc led to decreases in maximum SPS activity in leaves by 80 and 13%, respectively, whereas null mutants spsa2 and spsb had no significant effect. Consistently, isoform‐specific antibodies detected only the SPSA1 and SPSC proteins in leaf extracts. Leaf photosynthesis at ambient [CO2] was not different among the genotypes but was 20% lower in spsa1 mutants when measured under saturating [CO2] levels. Carbon partitioning at ambient [CO2] was altered only in the spsa1 null mutant. Cold treatment of plants (4 °C for 96 h) increased leaf soluble sugars and starch and increased the leaf content of SPSA1 and SPSC proteins twofold to threefold, and of the four null mutants, only spsa1 reduced leaf non‐structural carbohydrate accumulation in response to cold treatment. It is concluded that SPSA1 plays a major role in photosynthetic sucrose synthesis in Arabidopsis leaves, and decreases in leaf SPS activity lead to increased starch synthesis and starch turnover and decreased Ribulose 1,5‐bisphosphate regeneration‐limited photosynthesis but not ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco)‐limited photosynthesis, indicating a limitation of triose‐phosphate utilization (TPU).
Climate‐related trends in sapwood biophysical properties in two conifers: avoidance of hydraulic dysfunction through coordinated adjustments in xylem efficiency, safety and capacitance
Authors: BARNARD DAVID M. , MEINZER FREDERICK C. , LACHENBRUCH BARBARA , MCCULLOH KATHERINE A. , JOHNSON DANIEL M. , WOODRUFF DAVID R.
Published: February 2011

In the Pacific north‐west, the Cascade Mountain Range blocks much of the precipitation and maritime influence of the Pacific Ocean, resulting in distinct climates east and west of the mountains. The current study aimed to investigate relationships between water storage and transport properties in populations of Douglas‐fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) adapted to both climates. Sapwood thickness, capacitance, vulnerability to embolism, and axial and radial conductivity were measured on samples collected from trunks of mature trees. The sapwood of ponderosa pine was three to four times thicker than Douglas‐fir. Radial conductivity was higher in west‐side populations of both species, but axial conductivity was higher in the east‐side populations and in Douglas‐fir. Eastern populations of both species had sapwood that was more vulnerable to embolism than west‐side populations. Sapwood capacitance was similar between species, but was about twice as great in east‐side populations (580 kg m−3 MPa−1) as in west‐side populations (274 kg m−3 MPa−1). Capacitance was positively correlated with both mean embolism pressure and axial conductivity across species and populations, suggesting that coordinated adjustments in xylem efficiency, safety and water storage capacity may serve to avoid embolism along a gradient of increasing aridity.
Circadian control of root elongation and C partitioning in Arabidopsis thaliana
Authors: YAZDANBAKHSH NIMA , SULPICE RONAN , GRAF ALEXANDER , STITT MARK , FISAHN JOACHIM
Published: February 2011

Plants grow in a light/dark cycle. We have investigated how growth is buffered against the resulting changes in the carbon supply. Growth of primary roots of Arabidopsis seedlings was monitored using time‐resolved video imaging. The average daily rate of growth is increased in longer light periods or by addition of sugars. It responds slowly over days when the conditions are changed. The momentary rate of growth exhibits a robust diel oscillation with a minimum 8–9 h after dawn and a maximum towards the end of the night. Analyses with starch metabolism mutants show that starch turnover is required to maintain growth at night. A carbon shortfall leads to an inhibition of growth, which is not immediately reversed when carbon becomes available again. The diel oscillation persists in continuous light and is strongly modified in clock mutants. Central clock functions that depend on CCA1/LHY are required to set an appropriate rate of starch degradation and maintain a supply of carbon to support growth through to dawn, whereas ELF3 acts to decrease growth in the light period and promote growth in the night. Thus, while the overall growth rate depends on the carbon supply, the clock orchestrates diurnal carbon allocation and growth.
Sequential depolarization of root cortical and stelar cells induced by an acute salt shock – implications for Na+ and K+ transport into xylem vessels
Authors: WEGNER LARS H. , STEFANO GIOVANNI , SHABALA LANA , ROSSI MARIKA , MANCUSO STEFANO , SHABALA SERGEY
Published: February 2011

Early events in NaCl‐induced root ion and water transport were investigated in maize (Zea mays L) roots using a range of microelectrode and imaging techniques. Addition of 100 mm NaCl to the bath resulted in an exponential drop in root xylem pressure, rapid depolarization of trans‐root potential and a transient drop in xylem K+ activity (AK+) within ∼1 min after stress onset. At this time, no detectable amounts of Na+ were released into the xylem vessels. The observed drop in AK+ was unexpected, given the fact that application of the physiologically relevant concentrations of Na+ to isolated stele has caused rapid plasma membrane depolarization and a subsequent K+ efflux from the stelar tissues. This controversy was explained by the difference in kinetics of NaCl‐induced depolarization between cortical and stelar cells. As root cortical cells are first to be depolarized and lose K+ to the environment, this is associated with some K+ shift from the stelar symplast to the cortex, resulting in K+ being transiently removed from the xylem. Once Na+ is loaded into the xylem (between 1 and 5 min of root exposure to NaCl), stelar cells become more depolarized, and a gradual recovery in AK+ occurs.
Genomic divergence of allopatric sibling species studied by molecular cytogenetics of their F1 hybrids
Authors: Parokonny A. S. , Kenton A. Y. , Meredith L. , Owens S. J. , Bennett M. D.
Published: February 2011

Despite their similar karyotype morphology and close taxonomic affinity, the genomes of allopatric sibling species, Gibasis karwinskyana and Gibasis consobrina, are clearly distinguished in metaphases of their F1 hybrids by genomic in‐situ hybridization (GISH). The reduced ability of chromosomes from one species to bind labelled total DNA from the other involves almost the whole chromosome complement, and is equally pronounced in euchromatin and heterochromatin. The only region strongly conserved in the two species is an AT‐rich band proximal to each nucleolus organizer. Molecular differentiation is accompanied by chromosome pairing failure in the F1 interspecific hybrids, although the reason remains open to question. The two species also differ in their numbers of detectable sites for rRNA genes. The greater number of such sites in G. consobrina may be linked with a propensity for interchange heterozygosity. The ability to discriminate rapidly and reliably between the chromosomes of close relatives with almost identical karyotypes makes GISH invaluable in preliminary studies of phytogeny. Detection of even small conserved chromosome bands using GISH confirms the sensitivity of the technique and demonstrates its potential use in evolutionary cytogenetics. This will allow rapid re‐evaluation of many important genetic systems exposed by classical cytogenetics in previous decades.
Molecular analyses of a barley multigene family homologous to the yeast protein kinase gene SNF1
Authors: Halford Nigel G. , Vicente‐Carbajosa Jesus , Sabelli Paolo A. , Shewry Peter R. , Hannappel Ulrich , Kreis Martin
Published: February 2011

Genomic sequences homologous to the yeast gene SNF1 have been isolated from barley (Hordeum vulgare) cv. Sunbar. SNF1 encodes a protein serine/threonine kinase required for the derepression of a number of genes, including SUC2 (invertase) in response to glucose deprivation. Southern blotting showed the presence of a family of related genes in barley and full‐length sequences have been determined for two members of the family, one of which lacks an exon and is almost certainly non‐functional. A partial sequence has been obtained for a third member of the family. The transcription start site of one of the genes has been determined by S1 nuclease protection. A transcript almost identical in sequence to the exons of one of the genes has been amplified from barley endosperm mRNA using the polymerase chain reaction. One of the full‐length genomic sequences contains nine introns and 10 exons and the number and position of the introns in the second full‐length sequence is identical except that it lacks exon 2. However, the length and sequence of the introns vary. Northern blot analyses indicated that related transcripts are present in aleurones, coleoptiles, endosperms, internodes, leaves, ovules, roots and root tips, with highest levels of expression in the aleurones and endosperms.