bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarization switching dynamics by inhomogeneous field mechanism in ferroelectric polymers
Authors: Schütrumpf J , Zhukov S , Genenko Y A , von Seggern H 
Published: March 2012

Abstract
The understanding of polarization switching dynamics of ferroelectrics is of great importance for practical applications and has been steadily advanced for ferroelectric ceramics and polymers for more than half a century. The temporal behaviour of polarization reversal in ferroelectric copolymers such as P(VDF-TrFE) cannot be satisfactorily explained by simple models such as the classical Kolmogorov–Avrami–Ishibashi nucleation and growth theory.
In this paper the inhomogeneous field mechanism (IFM) model recently proposed for PZT ceramics has been applied to polymer ferroelectrics for the first time. The model is based on the assumption that the switching volume is divided into many spatial regions with independent dynamics, only determined by the local electric field. The local field values are randomly distributed over the ensemble of regions due to intrinsic inhomogeneities of the material. Therefore an inhomogeneous switching behaviour is induced by the varying local fields of each region. The statistical distribution of local field values can be directly extracted from the experimental data.
The model satisfactorily describes virgin P(VDF-TrFE) samples over a broad time-field domain covering eight orders of magnitude of poling time and electric field values from 30–150 kV mm−1. In the same way we can conclude that the IFM model is adaptive to both ferroelectric ceramics and semi-crystalline polymers.
Observation of a low-symmetry phase in Na0.5Bi0.5TiO3crystals by optical birefringence microscopy
Authors: Gorfman S. , Glazer A. M. , Noguchi Y. , Miyayama M. , Luo H. , Thomas P. A. 
Published: March 2012

Single crystals of sodium bismuth titanate (Na0.5Bi0.5TiO3, NBT) (pure and Mn-doped) have been investigated by means of optical birefringence microscopy. For both crystals, it was found that, above ∼573 K, the optical axis is perfectly aligned with one of the pseudocubic 〈001〉PCdirections, while the domain walls appearing in the images are parallel to the pseudocubic 〈011〉PCdirections. These observations are consistent with a tetragonal symmetry. Below ∼573 K, the observed optical orientation of both crystals shows a broad angular distribution, with no clearly visible crystallographically oriented domain walls. These results are consistent with monoclinic symmetry. Most importantly, the direct observation of the temperature-driven rotation of the optical axis within the monoclinic plane is reported for the first time in a perovskite oxide material, in the present case for Mn-doped NBT. This has consequences for the understanding of phase transitions in technologically relevant compounds, such as PbZr1−xTixO3, which are considered to have monoclinic structure in some parts of the phase diagram.
Influence of the matrix on the fractal properties of precipitated silica in composites
Authors: Schneider Gerald J. , Hengl W. , Brandt K. , Roth S. V. , Schuster R. , Göritz D. 
Published: March 2012

The influence of different interactions between polymer chains and the particle surface on the morphology of hierarchically structured silica were studied by means of small-angle X-ray scattering experiments and a thorough analysis. To realize different interaction strengths, the particles were dispersed in natural and nitrile rubber,i.e. matrices having different polarities. Changing the silica fraction renders the respective influences of particle–particle, cluster–cluster and polymer–particle interactions accessible. Thus, the interplay between external mechanical forces from the mixer, internal forces,e.g. caused by silica–silica collisions, and forces mediated by the polymers are addressed in detail. Mixing of particles and polymers affects all parameters related to the clusters, but not the primary particle structure. It is demonstrated that the external forces cause a change in cluster size as well as the internal forces arising from silica–silica collisions. There is no evidence that the different interaction strengths between polymer chains and particle surfaces influence the morphology. Hence, the mixing process dominates the final structure at the macroscopic scale but not the different interaction strength on the molecular scale.
Single and multiple dose intravenous and oral pharmacokinetics of the hedgehog pathway inhibitor vismodegib in healthy female subjects
Authors: Graham Richard A. , Hop Cornelis E. C. A. , Borin Marie T. , Lum Bert L. , Colburn Dawn , Chang Ilsung , Shin Young G. , Malhi Vikram , Low Jennifer A. , Dresser Mark J. 
Published: March 2012

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• While recent publications have suggested the pharmacokinetics (PK) of vismodegib appear to be non‐linear, there has not been a report describing the mechanisms of non‐linearity.WHAT THIS STUDY ADDS• This study provides evidence that two separate processes, namely, solubility‐limited absorption and concentration–dependent plasma protein binding, can explain the non‐linear PK of vismodegib. This study provides quantitative results which can account for the lower than expected accumulation of vismodegib with continuous daily dosing.AIM Vismodegib has demonstrated clinical activity in patients with advanced basal cell carcinoma. The pharmacokinetics (PK) of vismodegib are non‐linear. The objective of this study was to determine whether vismodegib PK change following repeated dosing by administering a tracer intravenous (i.v.) dose of 14C‐vismodegib with single and multiple oral doses.METHODS Healthy post menopausal female subjects (n= 6/group) received either a single or daily 150 mg vismodegib oral dose with a 14C‐labelled 10 µg i.v. bolus dose administered 2 h after the single or last oral dose (day 7). Plasma samples were assayed for vismodegib by LC‐MS/MS and for 14C‐vismodegib by accelerator mass spectrometry.RESULTS Following a single i.v. dose, mean clearance, volume of distribution and absolute bioavailability were 43.4 ml h−1, 16.4 l and 31.8%, respectively. Parallel concentration–time profiles following single oral and i.v. administration of vismodegib indicated elimination rate limited PK. Following i.v. administration at steady‐state, mean clearance and volume of distribution were 78.5 ml h−1 and 26.8 l, respectively. Comparison of i.v. PK parameters after single and multiple oral dosing showed similar half‐life, increased clearance and volume of distribution (81% and 63% higher, respectively) and decreased bioavailability (77% lower) after repeated dosing. Relative to single dose, the unbound fraction of vismodegib increased 2.4‐fold with continuous daily dosing.CONCLUSION Vismodegib exhibited a long terminal half‐life after oral and i.v. administration, moderate absolute bioavailability and non‐linear PK after repeated dosing. Results from this study suggest that the non‐linear PK of vismodegib result from two separate, non‐linear processes, namely solubility limited absorption and high affinity, saturable plasma protein binding.
Beneficial effects of Neotyphodium tembladerae and Neotyphodium pampeanum on a wild forage grass
Authors: Iannone L. J. , Pinget A. D. , Nagabhyru P. , Schardl C. L. , De Battista J. P. 
Published: March 2012

AbstractAsexual, vertically transmitted fungal endophytes of the genus Neotyphodium are considered to enhance growth, stress resistance and competitiveness of agronomic grasses, but have been suggested to have neutral or deleterious effects on wild grasses. We studied whether the associations between Bromus auleticus and their endophytes, Neotyphodium pampeanum and Neotyphodium tembladerae, are beneficial for this wild forage grass native to South America. In a greenhouse experiment, 3‐month‐old endophyte‐infected plants (E+) showed enhanced growth relative to their endophyte‐free counterparts (E−). In a one‐year‐long experiment in the field, E+ plants showed higher survival and regrowth rate, and produced more biomass and seeds than E− plants. Only with respect to the seed output did N. tembladerae seem to be detrimental, whereas N. pampeanum did not affect this parameter. No differences were observed with respect to the germination of seeds produced by E+ or E− plants. Loline alkaloids were detected in N. pampeanum‐infected plants. Our results show that, similar to results with agronomic grasses, in wild grasses, the symbiosis with Neotyphodium species could be mutualistic.
Effect of low‐dose N application and early mowing on plant species composition of mesophilous meadow grassland (Arrhenatherion) in Central Europe
Authors: Čámská K. , Skálová H. 
Published: March 2012

AbstractSemi‐natural temperate grasslands in Europe make an important contribution to biodiversity, but their existence has been endangered by both agricultural intensification and abandonment. In the Czech Republic, Arrhenatherion meadows are a typical example, with their conservation made difficult by the scarcity of research on effective management practices. We examined effects of two potentially useful approaches, application of 56 kg N ha−1 and earlier first mowing (i.e. in the middle of May, about 2 weeks earlier than usual), on species composition of an Arrhenatherion grassland in central Bohemia over a 7‐year period (1998–2004). These treatments did not influence species richness, but resulted in small changes in canopy structure in terms of cover of individual species and particular plant functional groups. N application resulted in increases in nitrophilous species and tall graminoids, especially Alopecurus pratensis, Festuca pratensis, Heracleum sphondylium and Ranunculus acris, and in decreases in short graminoids. Earlier mowing decreased tall herbs, especially H. sphondylium, and might thus be useful in compensating for increases in some nitrophilous species owing to N application. However, earlier mowing had negative impacts on spring‐flowering species in terms of reduced cover.
Models of intellectual disability: towards a perspective of (poss)ability
Authors: Mckenzie J. A. 
Published: March 2012

AbstractBackground  The social and medical models of disability configure the relationship between disability and impairment differently. Neither of these models has provided a comprehensive theoretical or practical basis for talking about intellectual disability (ID). Models that emphasise the interactive nature of disability appear to be more promising. This study explores the ways in which models of disability are reflected in disability discourse in an empirical discourse analysis conducted in the Eastern Cape Province of South Africa.Methods  Q methodology was used in this study as a discourse analysis tool. Adults with ID, parents of children with ID and professionals who work with people with ID completed a sorting task where they stated the degree to which they agreed or disagreed with statements that are made about people with ID. This exercise resulted in a pattern of responses for each participant, termed a Q sort and these were used as data in a factor analysis using dedicated Q method software. A second order factor analysis was then performed on the resulting factors.Results  Four discourses were identified: the Social Model/Human Rights Discourse, the Medical Model/Professional Religious Discourse, the Community Model/Community Religious Discourse and the Interactive Discourse. Except for the last one, each of these discourses adopts a model of disability with a static view of impairment as fixed. The Interactive Discourse appears to be related to dynamic, environmental conceptions of disability where competence is built through social interaction.Conclusions  A theory of (poss)ability is proposed and some of its concerns are suggested. This perspective views impairment as an interaction between individuals and their environment and postulates that competence is a function of context, rather than a property of the individual.
A texture–analysis–based design method for self‐adaptive focus criterion function
Authors: LIANG Q. , QU Y.F. 
Published: March 2012

SummaryAutofocusing (AF) criterion functions are critical to the performance of a passive autofocusing system in automatic video microscopy. Most of the autofocusing criterion functions proposed are dependent on the imaging system and image captured by the objective being focused or ranged. This dependence destabilizes the performance of the system when the criterion functions are applied to objectives with different characteristics. In this paper, a new design method for autofocusing criterion functions is introduced. This method enables the system to have the ability to tell the texture directional information of the objective. Based on this information, the optimal focus criterion function specific to one texture direction is designed, voiding blindly using autofocusing functions which cannot perform well when applied to the certain surface and can even lead to failure of the whole process. In this way, we improved the self‐adaptability, robustness, reliability and focusing accuracy of the algorithm. First, the grey‐level co‐occurrence matrices of real‐time images are calculated in four directions. Next, the contrast values of the four matrices are computed and then compared. The result reflects the directional information of the measured objective surfaces. Finally, with the directional information, an adaptive criterion function is constructed. To demonstrate the effectiveness of the new focus algorithm, we conducted experiments on different texture surfaces and compared the results with those obtained by existing algorithms. The proposed algorithm excellently performs with different measured objectives.
Involvement of multiple distinct Bordetella receptor proteins in the utilization of iron liberated from transferrin by host catecholamine stress hormones
Authors: Armstrong Sandra K. , Brickman Timothy J. , Suhadolc Ryan J. 
Published: March 2012

SummaryBordetella bronchiseptica is a pathogen that can acquire iron using its native alcaligin siderophore system, but can also use the catechol xenosiderophore enterobactin via the BfeA outer membrane receptor. Transcription of bfeA is positively controlled by a regulator that requires induction by enterobactin. Catecholamine hormones also induce bfeA transcription and B. bronchiseptica can use the catecholamine noradrenaline for growth on transferrin. In this study, B. bronchiseptica was shown to use catecholamines to obtain iron from both transferrin and lactoferrin in the absence of siderophore. In the presence of siderophore, noradrenaline augmented transferrin utilization by B. bronchiseptica, as well as siderophore function in vitro. Genetic analysis identified BfrA, BfrD and BfrE as TonB‐dependent outer membrane catecholamine receptors. The BfeA enterobactin receptor was found to not be involved directly in catecholamine utilization; however, the BfrA, BfrD and BfrE catecholamine receptors could serve as receptors for enterobactin and its degradation product 2,3‐dihydroxybenzoic acid. Thus, there is a functional link between enterobactin‐dependent and catecholamine‐dependent transferrin utilization. This investigation characterizes a new B. bronchiseptica mechanism for iron uptake from transferrin that uses host stress hormones that not only deliver iron directly to catecholamine receptors, but also potentiate siderophore activity by acting as iron shuttles.
Differential germination pattern of rice cultivars resistant to imidazolinone herbicides carrying different acetolactate synthase gene mutations
Authors: GOULART I C G R , MATZENBACHER F O , MEROTTO A 
Published: March 2012

Goulart ICGR, Matzenbacher FO & Merotto A JR (2012). Differential germination pattern of rice cultivars resistant to imidazolinone herbicides carrying different acetolactate synthase gene mutations. Weed Research52, 224–232.SummaryDifferent mutations in the acetolactate synthase (ALS) gene can affect the germination pattern and facilitate the occurrence of ALS‐inhibiting herbicide resistance in weedy red rice. The aim of this study was to evaluate the germination rates in imidazolinone‐resistant rice cultivars carrying three different ALS gene mutations. Plant material consisted of the imidazolinone‐resistant rice cultivars IRGA 422 CL, PUITÁ INTA CL and SATOR CL that carry the ALS mutations Gly654Glu, Ala122Thr and Ser653Asn, respectively, and the susceptible cultivar IRGA 417. Initially, the germination pattern of these cultivars was evaluated at temperatures of 15, 20, 25 and 30°C. Afterwards, five lots of each cultivar were evaluated at temperatures of 20 and 25°C to separate the environmental and genotypic effects. The environmental effect related to the different seed origin did not affect the germination rates of the rice cultivars. However, the germination pattern of the evaluated cultivars was different, mainly at 20°C. The time to reach 50% germination at 20°C for the imidazolinone‐resistant rice cultivars IRGA 422 CL, SATOR CL and PUITÁ INTA CL was 6, 16 and 24 h earlier, respectively, than the susceptible cultivar IRGA 417. The PUITÁ INTA CL cultivar, which carries the mutation Ala122Thr, showed faster germination than the other herbicide–resistant and the susceptible cultivars at 20°C. The faster germination that resulted from the resistance to ALS‐inhibiting herbicides could have different consequences for the establishment and competition of weedy red rice.
Increased serum baseline tryptase levels and extensive skin involvement are predictors for the severity of mast cell activation episodes in children with mastocytosis
Authors: Alvarez‐Twose I. , Vañó‐Galván S. , Sánchez‐Muñoz L. , Morgado J. M. , Matito A. , Torrelo A. , Jaén P. , Schwartz L. B. , Orfao A. , Escribano L. 
Published: March 2012

AbstractBackgroundDespite the good prognosis of pediatric mastocytosis, some patients suffer from severe mast cell (MC) mediator‐associated symptoms. The aim of this study was to identify predictors for severe MC mediator release symptoms in children with mastocytosis in the skin (MIS).MethodsSerum baseline total tryptase (sbT) levels in 111 children with MIS – 80 maculopapular cutaneous mastocytosis/plaque mastocytosis, 22 nodular mastocytosis, and nine diffuse cutaneous mastocytosis – were investigated as a predictive biomarker for the occurrence of MC mediator‐related signs and symptoms within the first 18 months after disease onset.ResultsTwelve children (11%) who showed extensive cutaneous disease involving >90% of body surface area (BSA) suffered from severe symptoms requiring hospitalization, with (n = 5) or without (n = 6) management in the intensive care unit (ICU) owing to life‐threatening complications. The median sbT was significantly (P < 0.001) higher in patients with extensive cutaneous disease vs those with <90% of BSA involved (45.5 vs 5.2 μg/l, respectively), as well as in children with grade 4 (severe mastocytosis‐related symptoms requiring emergency therapy and hospitalization) vs those with grade <4 (46.2 vs 5.2 μg/l, respectively). Receiver operating characteristics curve analyses showed that the optimal cutoff s for sbT to predict the need for daily antimediator therapy, hospitalization, and the management in an ICU were 6.6, 15.5, and 30.8 μg/l, respectively (sensitivity and specificity of 77% and 79%, 100% and 95%, and 100% and 96%, respectively).ConclusionsIncreased sbT in association with extensive cutaneous involvement identifies patients at risk for severe MC activation events in pediatric mastocytosis.
Antioxidant Enzyme Activity and mRNA Expression in Reproductive Tract of Adult Male European Bison (Bison bonasus, Linnaeus 1758)
Authors: Koziorowska‐Gilun M , Gilun P , Fraser L , Koziorowski M , Kordan W , Stefanczyk‐Krzymowska S 
Published: March 2012

ContentsAntioxidants in the male reproductive tract are the main defence factors against oxidative stress caused by reactive oxygen species production, which compromises sperm function and male fertility. This study was designed to determine the activity of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), in the testicular and epididymidal tissues of adult male European bison (Bison bonasus). The reproductive tract tissues were subjected to real‐time reverse transcriptase–polymerase chain reaction (RT‐PCR) analysis to quantify mRNA expression levels of five antioxidant enzymes: copper/zinc SOD (Cu/Zn SOD), secretory extracellular SOD (Ec‐SOD), CAT, phospholipid hydroperoxide glutathione peroxidase (PHGPx) and GPx5. The corpus and cauda epididymidal tissues displayed greater (p < 0.05) SOD activity compared with the testicular tissue. It was found that CAT activity was lowest (p < 0.05) in the cauda epididymidis, whereas negligible GPx activity was detected in the reproductive tract tissues. There were no detectable differences in the mRNA expression level of Cu/Zn SOD among the different reproductive tract tissues. Small amounts of Ec‐SOD mRNA were found in the reproductive tract, particularly in the epididymides. The caput and cauda epididymides exhibited greater (p < 0.05) level of CAT mRNA expression, whereas PHGPx mRNA was more (p < 0.05) expressed in the testis. Furthermore, extremely large amounts of GPx5 mRNA were detected in the caput epididymidal tissue compared with other tissues of the reproductive tract. It can be suggested that the activity of the antioxidant enzymes and the relative gene expression of the enzymes confirm the presence of tissue‐specific antioxidant defence systems in the bison reproductive tract, which are required for spermatogenesis, epididymal maturation and storage of spermatozoa.
Vascular Endothelial (VEGF) and Epithelial Growth Factor (EGF) as Well as Platelet‐Activating Factor (PAF) and Receptors are Expressed in the Early Pregnant Canine Uterus
Authors: Schäfer‐Somi S , Sabitzer S , Klein D , Reinbacher E , Kanca H , Beceriklisoy HB , Aksoy OA , Kucukaslan I , Macun HC , Aslan S 
Published: March 2012

ContentsThe aim of this study was to investigate the course of expression of platelet‐activating factor (PAF), PAF‐receptor (PAF‐R), epidermal growth factor (EGF), EGF‐R, vascular endothelial growth factor (VEGF), VEGF‐R1 and VEGF‐R2 in uterine tissue during canine pregnancy. For this purpose, 20 bitches were ovariohysterectomized at days 10–12 (n = 10), 18–25 (n = 5) and 28–45 (n = 5) days after mating, respectively. The pre‐implantation group was proven pregnant by embryo flushing of the uterus after the operation, the others by sonography. Five embryo negative, that is, non‐pregnant, bitches in diestrus (day 10–12) served as controls. Tissue samples from the uterus (placentation sites and horn width, respectively) were excised and snap‐frozen in liquid nitrogen after embedding in Tissue Tec®. Extraction of mRNA for RT‐PCR was performed with Tri‐Reagent. In the embryos, mRNA from all factors except VEGF was detected. In the course of pregnancy, significantly higher expression of PAF and PAFR as well as VEGF and VEGFR2 during the pre‐implantation stage than in all other stages and a strong upregulation of EGF during implantation were characteristic. The course of EGF was in diametrical opposition to the course of the receptor. These results point towards an increased demand for VEGF, EGF and PAF during the earliest stages of canine pregnancy.