bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive power capability of a wind turbine with doubly fed induction generator
Authors: Lund Torsten , Sørensen Poul , Eek Jarle 
Published: April 2007

AbstractThe aim of the work is to derive a steady state PQ‐diagram for a variable speed wind turbine equipped with a Doubly Fed Induction Generator. Firstly, the dependency between optimal rotor speed and wind speed is presented. Secondly, the limitations in reactive power production, caused by the rotor current, the rotor voltage and the stator current are derived. Thirdly, the influence of switching from Δ to Y coupling of the stator is investigated. Finally, a complete PQ diagram for a wind turbine is plotted. It is concluded that the limiting factor regarding reactive power production will typically be the rotor current limit, and that the limit for reactive power absorption will be the stator current limit. Further, it is concluded that the rotor voltage will only have a limiting effect at high positive and negative slips, but near the limitation, the reactive power capability is very sensitive to small changes in the slip. Copyright © 2007 John Wiley & Sons, Ltd.
Functional analysis of genes involved in the biosynthesis of isoprene in Bacillus subtilis
Authors: Julsing Mattijs K. , Rijpkema Michael , Woerdenbag Herman J. , Quax Wim J. , Kayser Oliver 
Published: April 2007

Abstract
In comparison to other bacteria Bacillus subtilis emits the volatile compound isoprene in high concentrations. Isoprene is the smallest representative of the natural product group of terpenoids. A search in the genome of B. subtilis resulted in a set of genes with yet unknown function, but putatively involved in the methylerythritol phosphate (MEP) pathway to isoprene. Further identification of these genes would give the possibility to engineer B. subtilis as a host cell for the production of terpenoids like the valuable plant-produced drugs artemisinin and paclitaxel. Conditional knock-out strains of putative genes were analyzed for the amount of isoprene emitted. Differences in isoprene emission were used to identify the function of the enzymes and of the corresponding selected genes in the MEP pathway. We give proof on a biochemical level that several of these selected genes from this species are involved in isoprene biosynthesis. This opens the possibilities to investigate the physiological function of isoprene emission and to increase the endogenous flux to the terpenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate, for the heterologous production of more complex terpenoids in B. subtilis.
Effect of Parathyroidectomy on Quality of Life and Neuropsychological Symptoms in Primary Hyperparathyroidism
Authors: Weber Theresia , Keller Monika , Hense Isabella , Pietsch Alexander , Hinz Ulf , Schilling Tobias , Nawroth Peter , Klar Ernst , Büchler Markus W. 
Published: April 2007

AbstractNeuropsychological symptoms are found in a certain number of patients with primary hyperparathyroidism (PHPT). Preoperative and postoperative quality of life, anxiety, and depression are measured to analyze the impact of parathyroidectomy on these symptoms. In this prospective study, 66 patients underwent parathyroidectomy for PHPT and were evaluated pre‐ and postoperatively with two validated psychometric instruments (HADS, PHQ‐9). Health‐related quality of life was measured with a 12‐item short‐form health survey (SF‐12). Preoperatively, the median physical component score (SF‐12) of 43.0 and mental component score of 43.5 were lower than those of the general population (52.8 and 54.2 points, respectively). One year postoperatively the mental component score increased to 48.6 (p = 0.011), whereas the physical functioning scale scored 45.3 and therefore did not change significantly (p = 0.585). Preoperatively, symptoms of depression were found in 23.4% of the patients, and 15.6% of the patients displayed symptoms of anxiety (HADS). The prevalence of depression was significantly higher in patients with preoperative serum calcium levels > 11.2 mg/dl (2.8 mmol/L) (p = 0.015). Twelve months postoperatively, the overall proportion of patients with anxiety and depression decreased to 7.8% and 15.7%, respectively (p = NS). The severity of depression as measured with the PHQ‐9 declined postoperatively as well. In this study, preoperative neuropsychological symptoms were related to the serum calcium levels. Postoperative health‐related quality of life improved significantly. Among patients with preoperative symptoms of depression and anxiety, both symptoms were alleviated significantly at the 12‐month follow‐up. Therefore, surgery for PHPT seems to be effective in reducing neuropsychological morbidity associated with PHPT.
Intermediate hyperhomocysteinaemia and compound heterozygosity for the common variant c.677C>T and a MTHFR gene mutation
Authors: Rummel T. , Suormala T. , Häberle J. , Koch H. G. , Berning C. , Perrett D. , Fowler B. 
Published: April 2007

SummaryMethylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the regulation of plasma homocysteine levels. MTHFR deficiency, an autosomal recessive disorder, results in homocystinuria and hypomethioninaemia and presents with highly variable symptoms affecting many organs but predominantly the central nervous system. The common polymorphism of the MTHFR gene, c.677C>T, a known risk factor for elevated plasma homocysteine levels, occurs frequently in the caucasian population. In this study we investigated three subjects with moderate hyperhomocysteinaemia (total plasma homocysteine 72 μmol/L in case 1 and 90 μmol/L in case 3, total non‐protein‐bound homocysteine 144–186 μmol/L in case 2) but different clinical presentation with no symptoms in case 1, muscle weakness at 17 years of age in case 2, and syncopes and cerebral convulsions at 18 years of age in case 3. Each subject was compound heterozygous for the c.677C>T polymorphism and a novel mutation of the MTHFR gene (case 1: c.883G>A [p.D291N]; case 2: c.1552_c.1553delGA [p.E514fsX536]; case 3: c.616C>T [p.P202S]). Moderately decreased fibroblast MTHFR activity was associated with severely reduced affinity for NADPH and increased sensitivity to inhibition by S‐adenosylmethionine (AdoMet) in case 2, and with mild FAD responsiveness in case 3. In case 1, fibroblast MTHFR activity was normal but the sensitivity to inhibition by AdoMet was slightly reduced. This study indicates that the sequence alteration c.677C>T combined with severe MTHFR mutations in compound heterozygous state may lead to moderate biochemical and clinical abnormalities exceeding those attributed to the c.677TT genotype and might require in addition to folate substitution further therapy to normalize homocysteine levels.
High incidence of autoantibodies in Fabry disease patients
Authors: Martinez P. , Aggio M. , Rozenfeld P. 
Published: April 2007

SummaryFabry disease (FD) is an X‐linked disorder of glycosphingolipid catabolism that results from a deficiency of the lysosomal enzyme α‐galactosidase A. This defect leads to the accumulation of its substrates, mainly globotriaosylceramide, in lysosomes of cells of different tissues. Different studies have shown the involvement of immunopathologies in different sphingolipidoses. The coexistence of FD and immune disorders such as systemic lupus erythematosus, rheumatoid arthritis and IgA nephropathy, has been described in the literature. The aim of this study was to evaluate the prevalence of a group of autoantibodies in a series of Argentine FD patients. Autoantibodies against extractable nuclear antigens (ENAs), double‐stranded DNA, anticardiolipin and phosphatidylserine were assayed by ELISA. Lupus anticoagulants were also tested. Fifty‐seven per cent of the samples showed reactivity with at least one autoantigen. Such reactivities were more frequent among males than among females. Antiphospholipid autoantibodies were detected in 45% of our patients. The high rate of thrombosis associated with FD could be related, at least in part, to the presence of antiphospholipid autoantibodies in Fabry patients. We found the presence of ENAs, which are a characteristic finding of rheumatological diseases, previous a frequent misdiagnosis of FD, in around 39% of the cases. The detection of a high level of autoantibodies must be correlated clinically to determine the existence of an underlying autoimmune disease. With the recent development of therapy, the life expectancy in FD will increase and autoimmune diseases might play an important role in the morbidity of FD.
Bovine mucopolysaccharidosis type IIIB
Authors: Karageorgos L. , Hill B. , Bawden M. J. , Hopwood J. J. 
Published: April 2007

SummaryMucopolysaccharidosis IIIB, an autosomal recessive lysosomal storage disorder of heparan sulfate caused by mutations in the α‐N‐acetylglucosaminidase (NAGLU) gene, was recently discovered in cattle. Clinical signs include progressive ataxia, stumbling gait, swaying and difficulty in balance and walking. These clinical signs are usually first observed at approximately 2 years of age and then develop progressively over the lifespan of the animals. Affected bulls were found to be homozygous for the missense mutation E452K (c.1354G> A). The availability of mutational analysis permits screening for the NAGLU mutation to eradicate this mutation from the cattle breeding population.
Neuregulin 1 is a pronociceptive cytokine that is regulated by progesterone in the spinal cord: Implications for sex specific pain modulation
Authors: LaCroix‐Fralish Michael L. , Tawfik Vivianne L. , Nutile‐McMenemy Nancy , DeLeo Joyce A. 
Published: April 2007

AbstractSex differences in the magnitude of response to thermal and tactile stimuli have been demonstrated in both clinical and animal studies. Females typically display lower threshold responses to painful stimuli as compared to males. We have previously observed sexually dimorphic expression of the growth factor, neuregulin 1 (NRG1) following L5 nerve root ligation (LR) in male and female rats. In the present study, we sought to determine which gonadal hormones were involved in regulating NRG1 expression following L5 nerve root ligation. We observed that expression of NRG1 mRNA and the neuregulin receptors, ErbB2 and ErbB4 in the lumbar spinal cord was facilitated by the presence of progesterone in female rats following L5 nerve root ligation. An increase in NRG1 protein and NRG1 immunoreactivity was also observed in the ipsilateral spinal cord of progesterone treated female rats as compared to ovariectomized female rats and male rats at day 14 following LR. NRG1 immunoreactivity was equally colocalized with either the astrocytic marker, GFAP, and with NeuN labeled neurons 14days following L5 nerve root ligation. Intrathecal administration of recombinant NRG1‐β1 protein significantly decreased the hindpaw tactile withdrawal threshold in male rats, ovariectomized female rats, and progesterone treated female rats. These results demonstrate a role for progesterone‐dependent regulation of glial and/or neuronal neuregulin 1 in female rats in mediating sex differences in nociception. Furthermore, our results suggest that NRG1 may be involved in central sensitization during the maintenance phase, but not in the initiation of persistent pain in female rats.
Status‐signalling chemical badges in male Iberian rock lizards
Authors: MARTÍN J. , MOREIRA P. L. , LÓPEZ P. 
Published: April 2007

Summary

Male competition for females often results in the evolution of conspicuous male traits that signal fighting ability or dominance status. Most studies examining mechanisms allowing these traits to function as reliable status signals (or badges) have focused on conspicuous visual or acoustic traits. However, many animals communicate chemically, and chemical traits alone may also signal male dominance status.
We examined whether chemicals in femoral gland secretions of male Iberian rock lizards (Lacerta monticola monticola Boulenger 1905) may signal dominance status.
In staged encounters, larger males were dominant over smaller ones. While controlling for male body size, males of higher dominance status produced femoral secretions with higher proportions of hexadecanol and octadecanol.
Tongue‐flick assays showed that males were able to (1) discriminate, by chemosensory cues alone, the different concentrations of hexadecanol from other chemicals presented in femoral secretions; (2) respond aggressively towards hexadecanol while responding neutrally towards other chemicals; and (3) show differential chemosensory and aggressive behaviours towards hexadecanol according to their own dominance status.
These results suggest that hexadecanol may be a reliable status badge. Moreover, because hexadecanol elicits male aggressive behaviour, subordinate males signalling high status (‘cheaters’) may end up paying high fighting costs. In addition, males that had higher dominance status, and that allocated higher proportions of hexadecanol to femoral secretions, had greater T‐cell immune responses. This result suggests a possible link between quality of the immune system, dominance status, and chemical signals.
Maternal carotenoid supplementation does not affect breeding performance in the Great Tit (Parus major)
Authors: REMEŠ VLADIMÍR , KRIST MILOŠ , BERTACCHE VITTORIO , STRADI RICCARDO 
Published: April 2007

Summary

Carotenoids are micronutrients with many beneficial health‐related effects. They are effective antioxidants and stimulants of the immune system. Carotenoids cannot be synthesized in animals and must be obtained from food. As such, they may limit reproductive output and performance, and on the proximate level mediate reproductive trade‐offs.
We studied carotenoid limitation in wild Great Tits (Parus major) by supplementing prelaying and laying females with lutein, the most abundant carotenoid in this species. We followed the effects of this supplementation on egg yolk carotenoid composition, and offspring and parental performance.
Females transferred the supplemented lutein into egg yolks, increasing lutein concentration to the upper limit of naturally occurring concentrations in control pairs. Concentrations of zeaxanthin, β‐carotene and α‐carotene did not differ between supplemented and control pairs.
Effects on offspring and parental performance were generally absent or weak. There were no effects on timing of laying, clutch size, hatching success, nestling survival, nestling mass (day 6 and 14), tarsus length or T‐cell mediated immune response. Males on supplemented nests fed their young more than those on control nests. There was no positive effect on female feeding or mass.
Negligible effects of lutein supplementation on offspring and parental performance might be explained by high natural abundance of carotenoids or other antioxidants, where additional carotenoids bear no strong advantage to the birds. Additionally, conflicting results of different studies may be explained by species‐specific features of their life‐histories.
A functional approach to sexual selection
Authors: IRSCHICK DUNCAN J. , HERREL ANTHONY , VANHOOYDONCK BIEKE , DAMME RAOUL VAN 
Published: April 2007

Summary

Sexual selection theory is a robust and dynamic field within evolutionary biology, yet despite decades of research, remarkably little is known of the mechanistic bases of mate choice and male competition.
Because many aspects of sexual selection involve dynamic movements, and are physically challenging, the limits of sexual selection may be defined by key functional and physiological variables (i.e. the ‘functional approach’).
We advocate the functional approach for providing mechanistic resolution on the adaptive basis of sexual structures and signals, the nature of mate choice and how males compete, among other issues.
An overview of recent work, highlighted in this special issue, shows that many features of sexual selection, including the outcome of male fights, the morphology and design of sexual signals, and the nature of mate choice, all appear to be dictated in large part by functional and physiological parameters.
We argue that the functional approach provides a potent tool for resolving several unresolved issues in sexual selection theory, particularly the nature of male quality, the handicap and indicator models of sexual selection, and the basis of mate choice.
Historical changes in the phenology of British Odonata are related to climate
Authors: HASSALL CHRISTOPHER , THOMPSON DAVID J. , FRENCH GRAHAM C. , HARVEY IAN F. 
Published: April 2007

AbstractResponses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates significantly advanced the leading edge (first quartile date) of the flight period by a mean of 1.51 ±0.060 (SEM, n=17) days per decade or 3.08±1.16 (SEM, n=17) days per degree rise in temperature when phylogeny is controlled for. This study represents the first review of changes in odonate phenology in relation to climate change. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared with terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa.
Effects of elevated atmospheric CO2, cutting frequency, and differential day/night atmospheric warming on root growth and turnover of Phalaris swards
Authors: VOLDER ASTRID , GIFFORD ROGER M. , EVANS JOHN R. 
Published: April 2007

AbstractWe investigated seasonal root production and root turnover of fertilized and well‐watered monocultures of Phalaris for 2 years using minirhizotrons installed in six newly designed temperature gradient tunnels, combined with sequential soil coring. Elevated atmospheric CO2 treatments were combined with two cutting frequencies and three warming scenarios: no warming, +3.0/+3.0 and +2.2/+4.0°C (day/night) atmospheric warming. The elevated CO2 treatment increased both new and net root length production primarily when combined with atmospheric warming, where the constant warming treatment had a greater positive effect than the increased night‐time warming treatment. Responses to elevated CO2 were greater when the swards were cut more frequently and responsiveness varied with season. For Phalaris swards, 17% of total net primary productivity went belowground. On account of root turnover, only one‐third of the new roots produced in the year following establishment could be expected, on average, to be recovered from soil cores. The interaction between the effects of CO2 and warming, combined with the differential effects of the two warming treatments, has important implications for modelling belowground responses to projected climate change.
Predicting adaptive evolution under elevated atmospheric CO2 in the perennial grass Bromus erectus
Authors: STEINGER THOMAS , STEPHAN ANDRÉ , SCHMID BERNHARD 
Published: April 2007

AbstractIncreasing concentrations of CO2 in the atmosphere are likely to affect the ecological dynamics of plant populations and communities worldwide, yet little is known about potential evolutionary consequences of high CO2. We employed a quantitative genetic framework to examine how the expression of genetic variation and covariation in fitness‐related traits, and thus, the evolutionary potential of a species, is influenced by CO2. In two field experiments, genotypes of the dominant grassland perennial Bromus erectus were grown for several years in plots maintained at present‐day or at elevated CO2 levels. Under noncompetitive conditions (experiment 1), elevated CO2 had little impact on plant survival, growth, and reproduction. Under competitive conditions in plots with diverse plant communities (experiment 2), performance of B. erectus was reduced by elevated CO2. This suggests that the effect of CO2 was largely indirect, intensifying competitive interactions. Elevated CO2 had significant effects on the expression of genetic variation in both the competitive and noncompetitive environment, but the effects were in opposite direction. Heritability of plant size was generally higher at elevated than at ambient CO2 in the noncompetitive environment, but lower in the competitive environment. Selection analysis revealed a positive genotypic selection differential for plant size at ambient CO2, indicating selection favoring genotypes with high growth rate. At elevated CO2, the corresponding selection differential was nonsignificant and slightly negative. This suggests that elevated CO2 is unlikely to stimulate the evolution of high biomass productivity in this species.
Shift in birch leaf metabolome and carbon allocation during long‐term open‐field ozone exposure
Authors: KONTUNEN‐SOPPELA SARI , OSSIPOV VLADIMIR , OSSIPOVA SVETLANA , OKSANEN ELINA 
Published: April 2007

AbstractCurrent and future ozone concentrations have the potential to reduce plant growth and increase carbon demand for defence and repair processes, which may result in reduced carbon sink strength of forest trees in long‐term. Still, there is limited understanding regarding the alterations in plant metabolism and variation in ozone tolerance among tree species and genotypes. Therefore, this paper aims to study changes in birch leaf metabolome due to long‐term realistic ozone stress and to relate these shifts in the metabolism with growth responses. Two European white birch (Betula pendula Roth) genotypes showing different ozone sensitivity were growing under 1.4–1.7 × ambient ozone in open‐field conditions in Central Finland. After seven growing seasons, the trees were analysed for changes in leaf metabolite profiling, based on 339 low molecular weight compounds (including phenolics, polar and lipophilic compounds, and pigments) and related whole‐tree growth responses. Genotype caused most of the variance of metabolite concentrations, while ozone concentration was the second principal component explaining the metabolome profiling. The main ozone caused changes included increases in quercetin‐phenolic compounds and compounds related to leaf cuticular wax layer, whereas several compounds related to carbohydrate metabolism and function of chloroplast membranes and pigments (such as chlorophyll‐related phytol derivatives) were decreasing. Some candidate compounds such as surface wax‐related squalene, 1‐dotriacontanol, and dotriacontane, providing growth‐related tolerance against ozone were demonstrated. This study indicated that current growth‐based ozone risk assessment methods are inadequate, because they ignore ecophysiological impacts due to alterations in leaf chemistry.