bluuebunny/crossref_metadata_2025_split huggingface dataset:
Different types of sub‐alpine grassland respond similarly to elevated nitrogen deposition in terms of productivity and sedge abundance
Authors: Bassin Seraina , Schalajda Juliane , Vogel Andreas , Suter Matthias 
Published: May 2012

AbstractQuestionIncreasing emissions of reactive nitrogen (N) compounds threaten the composition of species‐rich communities even in remote alpine areas. In the few studies available from (sub‐)alpine grassland, N deposition altered species composition in favour of sedges, which are assumed to be less limited by phosphorus (P) compared to other species. Is the magnitude of the sedges' relative increase modified by availability of other nutrients, which is in turn influenced by site‐specific edaphic and climatic conditions?LocationSwiss Central Alps.MethodsWe selected ten sub‐alpine sites that covered a broad range of communities and soil conditions, including both calcareous Seslerietum as well as acidic Nardetum pastures. As a model species, Carex sempervirens Vill. was present at each site. For two consecutive years, in addition to a control, two treatments were applied to the vegetation: (1) 50 kg·N·ha−1·yr−1 as NH4NO3 and (2) compound NPK fertilizer comprising the same amount of N. Total above‐ground biomass, fraction of all sedges, leaf length and leaf N, P and potassium (K) content of C. sempervirens were recorded and analysed for their responses to treatments and interaction with variables linked to productivity and nutrient availability (including soil water potential, pH and soil P).ResultsBiomass production was stimulated across all sites on average by 30% with elevated N deposition, and by 60% with NPK fertilizer application, revealing the sites to be similarly co‐limited by N and by P and K. Also across all sites, the fraction of sedges was increased on average 33% by N addition, but remained constant with NPK application, suggesting stronger P and/or K co‐limitation in non‐sedge species. N treatment effects were consistent in their direction but varied between sites; nevertheless this variation could not be explained by the measured edaphic or climatic factors. However, by trend, sedges benefited more from N fertilization on sites with higher pH, but benefited less on very dry sites.ConclusionOur findings reveal that the observed increase of sedges is a general response of sub‐alpine grassland to elevated N deposition and thus can be regarded as universal both for Seslerietum as well as Nardetum pastures.
Forest fire history, aspen and goat willow in a Fennoscandian old‐growth landscape: are current population structures a legacy of historical fires?
Authors: Lankia Heini , Wallenius Tuomo , Várkonyi Gergely , Kouki Jari , Snäll Tord 
Published: May 2012

AbstractQuestionsIs the current aspen or goat willow populations in boreal old‐growth forest a legacy of the historical fires?LocationA middle‐boreal, old‐growth forest landscape with a large proportion of wetlands in eastern Finland.MethodForest fire history of a 2100‐ha area was reconstructed using fire scars, forest age estimates and the presence or absence of charred stumps and charcoal particles in the soil in 63 systematically located plots. Age and size structures of aspen and goat willow were studied in a subsample of 12 plots.ResultsDuring the past 400 yr, forest fires have been seven times more numerous in the study area than could be expected based on modern lightning fire statistics. The ages of mature aspens (average 177 and maximum 213 yr) and mature goat willows (average 111 and maximum 173 yr) were higher than earlier reported, strikingly so in goat willow. Aspen age structure clearly reflected the past fires. Most aspens originated from the beginning of the 19th century, during a period of frequent forest fires. The regeneration of aspen leading to mature trees has been very low since the cessation of forest fires in the late 19th century. In turn, goat willow has also regenerated in spite of the absence of fires.ConclusionsThe majority of the mature aspen trees were recruited at the time of the last fires, and there was a notable lack of middle‐aged trees. This relationship to fires was not valid for goat willow. The main reason for the lack of young aspen cohorts in aspen populations in Fennoscandian old‐growth stands is most likely the lack of forest fires. Small‐scale gap dynamics cannot offset the lack of large‐scale disturbances, such as forest fires, for the regeneration of aspen, possibly because of the prevailing herbivory and competitive effects. Hence, the population decline of aspen is likely to continue and to threaten a wealth of species specialized on aspen in boreal forests.
Functional trait state diversity of Andean forests in Venezuela changes with altitude
Authors: Duivenvoorden Joost F. , Cuello A Nidia L. 
Published: May 2012

AbstractQuestionIt is presumed that environmental stress is more pronounced at higher altitudes in Andean forests due to lower rates of temperature‐constrained processes of growth, nutrient uptake and decomposition. Because community assembly theory predicts a low variation in viable traits under conditions of strong ecological filtering, we asked if the diversity in plant traits related to productivity and reproduction would decrease upslope.LocationGuaramacal National Park in the Andes of Venezuela (9°05‐21′N, 70°‐20′W).MethodsWe studied altitudinal patterns in the number of trait states of seven categorical traits found among vascular plants (DBH ≥ 2.5 cm) in 35 0.1‐ha plots between 1330 and 2890 m. Information on plant traits was obtained from literature and herbaria. To test the altitudinal correlations, we permuted the plot‐to‐species matrix by randomly selecting species from the entire species pool (conserving the species richness and the species–abundance pattern in each plot), applying no restrictions and by creating plot‐wise null assemblages of species that most likely occurred near a particular plot. In addition, the altitudinal pattern of trait states was examined using fourth‐corner analysis.ResultsBoth null model tests yielded similar results. The trait state diversity in fruit size decreased upslope. Plants with small fruits were mostly, but not exclusively, found at higher altitudes, whereas plants with large fruits occurred only at lower elevations. Leaf size showed more states at higher altitudes but this pattern disappeared when rare leaf size classes were down‐weighted. The upslope decrease in fruit size might be explained by the relatively low tree height of the upper montane rain forests, the increased selection for large seeds at high temperatures downslope, and the upslope decrease of large‐leaved taxa (in view of Corner's rule).ConclusionsThe functional diversity of important plant traits changed with altitude at Guaramacal. Altitudinal effects on plant trait responses should be controlled for in studies that monitor the degradation of functional diversity in Andean forests in relation to human influence.
The performance of Mediterranean subshrubs depends more on microsite than on regional climate conditions
Authors: Gazol Antonio , Julio Camarero J. 
Published: May 2012

AbstractQuestionTo what extent do small‐scale biotic interactions and local variations determine the spatial pattern and plant performance of three Mediterranean subshrubs growing under contrasting climatic conditions?LocationThree sites subjected to climatically contrasting conditions in Aragón (Javalambre, cold site; Bernués, mesic site; Monegros, xeric site), NE Spain.MethodsThe three species studied were Hormathophylla spinosa, Ononis fruticosa and Linum suffruticosum in the cold, mesic and xeric sites, respectively. Two transects (100 × 5 m) were located in each site, one in the upper part and another in the north‐oriented slope of a hill. All adult individuals located within each transect of each species were tagged, spatially located and their size measured (height and crown diameter). We also estimated visually the cover of other woody species around each subshrub individual to study inter‐specific interactions. We estimated the age of all subshrub individuals by counting annual rings in basal wood sections. To investigate the spatial patterns and plant performance of the three species we used spatial point pattern analyses and structural equation modelling.ResultsThe density of individuals and the spatial pattern of the species varied greatly among and within sites. H. spinosa and L. suffruticosum showed higher variability in density among transects and a more aggregated spatial pattern than O. fruticosa. Similarly, the three subshrubs presented different architecture and performed differently in the two transects studied for each species. All three species presented higher growth rates in the upper part of the hill than in the north‐oriented slope. Inter‐specific interactions were more important than intra‐specific ones in determining the performance of the three subshrubs, and were more intense in the case of H. spinosa and L. suffruticosum than in the case of O. fruticosa.ConclusionsOur results demonstrate that the spatial patterns of the three species studied varied within sites as a function of local environmental conditions. Moreover, plant–plant interactions can play an important role in explaining subshrub spatial patterns and performance in Mediterranean ecosystems. Inter‐ and intra‐specific interactions acting at local scales should be considered for understanding the responses of Mediterranean subshrubs to regional climate.
A Novel Nonsense Mutation in HSD17B3 Gene in a Tunisian Patient with Sexual Ambiguity
Authors: Ben Rhouma Bochra , Belguith Neila , Mnif Mouna Feki , Kamoun Thouraya , Charfi Nadia , Kamoun Mahdi , Abdelhedi Fatma , Hachicha Mongia , Kamoun Hassen , Abid Mohamed , Fakhfakh Faiza 
Published: May 2012

ABSTRACT

Introduction
17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) isoenzyme is present almost exclusively in the testes and converts delta 4 androstenedione to testosterone. Mutations in the HSD17B3 gene cause HSD17B3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD).

Aim
This study aimed to present the clinical and biochemical features of a Tunisian patient who presented a sexual ambiguity orienting to HSD17B3 deficiency and to search for a mutation in the HSD17B3 gene by DNA sequencing.

Methods
Polymerase chain reaction (PCR) amplification and subsequent sequencing of all the coding exons of HSD17B3 gene were performed on genomic DNA from the patient, her family, and 50 controls.

Results
Genetic mutation analysis of the HSD17B3 gene revealed the presence of a novel homozygous nonsense mutation in the exon 9 (c.618 C &gt; A) leading to the substitution p.C206X. The mutation p.C206X in the coding exons supports the hypothesis of HSD17B3 deficiency in our patient.

Conclusion
The patient described in this study represented a new case of a rare form of 46,XY DSD, associated to a novel gene mutation of HSD17B3 gene. The screening of this mutation is useful for confirming the diagnosis of HSD17B3 deficiency and for prenatal diagnosis.
Non‐alpha‐adrenergic effects on systemic vascular conductance during lower‐body negative pressure, static exercise and muscle metaboreflex activation
Authors: Kiviniemi A. M. , Frances M. F. , Rachinsky M. , Craen R. , Petrella R. J. , Huikuri H. V. , Tulppo M. P. , Shoemaker J. K. 
Published: May 2012

AbstractAimThis study tested the hypothesis that non‐α‐adrenergic mechanisms contribute to systemic vascular conductance (SVC) in a reflex‐specific manner during the sympathoexcitatory manoeuvres.MethodsTwelve healthy subjects underwent lower‐body negative pressure (LBNP, −40 mmHg) as well as static handgrip exercise (HG, 20% of maximal force) followed by post‐exercise forearm circulatory occlusion (PECO, 5 min each) with and without α‐adrenergic blockade induced by phentolamine (PHE). Aortic blood flow, finger blood pressure and superficial femoral artery blood flow were measured to calculate cardiac output, SVC and leg vascular conductance (LVC) during the last minute of each intervention.ResultsMean arterial pressure (MAP) decreased more during LBNP with PHE compared with saline (−7 ± 7 vs. −2 ± 5%, P = 0.016). PHE did not alter the MAP response to HG (+20 ± 12 and +24 ± 16%, respectively, for PHE and saline) but decreased the change in MAP during PECO (+12 ± 7 vs. +21 ± 14%, P = 0.005). The decrease in SVC and LVC with LBNP did not differ between saline and PHE trials (−13 ± 10 vs. −17 ± 10%, respectively, for SVC, P = 0.379). In contrast, the SVC response to HG increased from −9 ± 12 with saline to + 5 ± 15% with PHE (P = 0.002) and from −16 ± 15 with saline to +1 ± 16% with PHE during PECO (P = 0.003). LVC responses to HG or PECO were not different from saline with PHE.ConclusionsNon‐α‐adrenergic vasoconstriction was present during LBNP. The systemic vasoconstriction during static exercise and isolated muscle metaboreflex activation, in the absence of leg vasoconstriction, was explained by an α‐adrenergic mechanism. Therefore, non‐α‐adrenergic vasoconstriction is more emphasized during baroreflex, but not metaboreflex‐mediated sympathetic activation.
A prospective study of PTSD following recovery from first‐episode psychosis: The threat from persecutors, voices, and patienthood
Authors: Brunet Kat , Birchwood Max , Upthegrove Rachel , Michail Maria , Ross Kerry 
Published: May 2012

Objectives. Approximately one third of people with early psychosis report post‐traumatic symptoms, some of which are thought to arise from traumatic experiences associated with psychosis itself. This prospective study tested hypotheses based on retrospective findings that threat appraisals of voices, persecutors, or the new label of ‘mental health patient’ predict symptoms of post‐traumatic stress disorder (PTSD).Methods. Appraisals of power and threat from voices and other persecutors and appraisals of the threat posed to identity by the diagnosis were assessed during the first acute phase of psychosis. Eighteen months later, PTSD symptom levels and diagnosis were established.Design. Prospective.Results. Of 39 participants who completed the follow‐up phase, 12 (31%) met criteria for PTSD diagnosis. Nineteen (49%) of the participants were still distressed by memories of their psychosis or the associated treatment. During the acute phase of psychosis, appraisals of threat from voices and persecutors were strongly associated with distress. With the exception of the perceived ability to cope with threat, none of these appraisals were predictive of subsequent post‐traumatic stress however. Similarly, only one appraisal of the diagnosis (loss of control) was predictive of PTSD.Conclusion. It may be that retrospective studies have overestimated the influence of candidate appraisals in predicting PTSD. It might also be that assessments made during the acute phase of psychosis preceded a key phase of psychological processing that takes place during the immediate aftermath of the psychotic episode. A staged prospective design is required to uncover the true impact of psychosis on PTSD.
Effect of image quality on calcification detection in digital mammography
Authors: Warren Lucy M. , Mackenzie Alistair , Cooke Julie , Given‐Wilson Rosalind M. , Wallis Matthew G. , Chakraborty Dev P. , Dance David R. , Bosmans Hilde , Young Kenneth C. 
Published: May 2012

Purpose:This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection.Methods:One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica‐2) image processing. All other image qualities were processed with Agfa (Musica‐2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data.Results:There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising.Conclusions:Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection.
Signal detection and location‐dependent noise in cone‐beam computed tomography using the spatial definition of the Hotelling SNR
Authors: Brunner Claudia C. , Abboud Samir F. , Hoeschen Christoph , Kyprianou Iacovos S. 
Published: May 2012

Purpose:Quality assurance in computed tomography (CT) is commonly performed with the Fourier‐based modulation transfer function (MTF) and the noise variance, while more recently the noise power spectrum (NPS) has increased in popularity. The Fourier‐based methods make assumptions such as shift‐invariance and cyclostationarity. These assumptions are violated in real clinical systems and consequently are expected to result in systematic errors. A spatial approach, based on the object transfer matrix (T) and the covariance matrix (K) theory, does not require these assumptions and can provide a more general description of the imaging system. In this paper, the authors present an experimental methodology and data treatment for quality assessment of a lab cone‐beam CT system by comparing the spatial with the Fourier approach in 2D reconstructed slices.Methods:In order to have control over all experimental parameters and image reconstruction, a bench‐top flat‐panel‐based cone‐beam CT scanner and a cylindrical water‐filled poly(methyl methacrylate) (PMMA) phantom were used for the noise measurements. An aluminum foil inserted in the water phantom enabled the estimation of the line response function (LRF) with a limited number of assumptions. The authors evaluated the spatial blur, the noise and the signal‐to‐noise ratio (SNR) using the spatial approach as well as the Fourier‐based approach. In order to evaluate the degree of noise nonstationarity of their cone‐beam CT system, the authors evaluated both the local and global CT noise properties and compared them using both approaches.Results:For the laboratory cone‐beam CT, the location‐dependent noise evaluation showed that in addition to the noise variance, the NPS and covariance eigenvector symmetry depend on the location in the image. The estimated signal transfer was similar for both approaches. Unlike the Fourier approach which uses the same exponential wave function basis for both MTF and NPS, the eigenvectors ofT and K were significantly different.Conclusions:By using the eigenvectors of the noise and object transfer to characterize the system, the spatial approach provides additional information to the Fourier approach and is therefore an important tool for a thorough understanding of a CT system.
Analysis of Variola and Vaccinia Virus Neutralization Assays for Smallpox Vaccines
Authors: Hughes Christine M. , Newman Frances K. , Davidson Whitni B. , Olson Victoria A. , Smith Scott K. , Holman Robert C. , Yan Lihan , Frey Sharon E. , Belshe Robert B. , Karem Kevin L. , Damon Inger K. 
Published: May 2012

ABSTRACT
Possible smallpox reemergence drives research for third-generation vaccines that effectively neutralize variola virus. A comparison of neutralization assays using different substrates, variola and vaccinia (Dryvax and modified vaccinia Ankara [MVA]), showed significantly different 90% neutralization titers; Dryvax underestimated while MVA overestimated variola neutralization. Third-generation vaccines may rely upon neutralization as a correlate of protection.
Molecular Epidemiologic Analysis and Antimicrobial Resistance of Helicobacter cinaedi Isolated from Seven Hospitals in Japan
Authors: Rimbara Emiko , Mori Shigetarou , Matsui Mari , Suzuki Satowa , Wachino Jun-ichi , Kawamura Yoshiaki , Shen Zeli , Fox James G. , Shibayama Keigo 
Published: May 2012

ABSTRACT

Helicobacter cinaedi
colonizes the colons of human and animals and can cause colitis, cellulitis, and sepsis in humans, with infections in immunocompromised patients being increasingly recognized. However, methods for analyzing the molecular epidemiology of
H. cinaedi
are not yet established. A genotyping method involving multilocus sequence typing (MLST) was developed and used to analyze 50
H. cinaedi
isolates from Japanese hospitals in addition to 6 reference strains. Pulsed-field gel electrophoresis (PFGE) results were also compared with the MLST results. Based on the genomic information from strain CCUG18818, 21 housekeeping genes were selected as candidates for MLST and were observed to have high homology (96.5 to 100%) between isolates. Following a comparison of the 21 housekeeping genes from 8
H. cinaedi
isolates, 7 genes were chosen for MLST, revealing 14 sequence types (STs). The isolates from 3 hospitals belonged to the same STs, but the isolates from the other 4 hospitals belonged to different STs. Isolates belonging to ST6 were analyzed by PFGE and showed similar, but not identical, patterns between isolates. Isolates belonging to ST9, ST10, and ST11, which belonged to the same clonal complex, had the same pattern. All isolates were found to contain mutations in GyrA and the 23S rRNA gene that confer ciprofloxacin and clarithromycin resistance, respectively, in
H. cinaedi
. These results raise concerns about the increase in
H. cinaedi
isolates resistant to clarithromycin and ciprofloxacin in Japan.
The Structure of an Archaeal Viral Integrase Reveals an Evolutionarily Conserved Catalytic Core yet Supports a Mechanism of DNA Cleavage in
trans
Authors: Eilers Brian J. , Young Mark J. , Lawrence C. Martin 
Published: May 2012

ABSTRACT

The first structure of a catalytic domain from a hyperthermophilic archaeal viral integrase reveals a minimal fold similar to that of bacterial HP1 integrase and defines structural elements conserved across three domains of life. However, structural superposition on bacterial Holliday junction complexes and similarities in the C-terminal tail with that of eukaryotic Flp suggest that the catalytic tyrosine and an additional active-site lysine are delivered to neighboring subunits in
trans
. An intramolecular disulfide bond contributes significant thermostability
in vitro
.