bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequency‐based fatigue analysis of non‐stationary switching random loads
Authors: BENASCIUTTI D. , TOVO R. 
Published: October 2007

ABSTRACTThe service loadings in real systems are not only random, but also non‐stationary. The spectral methods based on a frequency‐domain characterization of random loads, which have been used in alternative to classical time‐domain approaches, cannot be applied to non‐stationary loads, because the conventional spectral density spectrum is not able to capture the evolutionary frequency characteristics of non‐stationary loads. This clearly restricts the applicability of the existing frequency‐based methods only to loads which are stationary. At the same time, it is also very difficult to propose general models valid for all types of load non‐stationarity encountered in practice. Therefore, a practical approach is to restrict the analysis to a specific class of non‐stationary loads; in this work, we consider particular non‐stationary loads (i.e. switching loads), which are piecewise stationary in their variance. A frequency‐domain analysis of such loads is proposed, which is based on a combination of the frequency‐based analysis of each adjacent stationary segment, which can be either Gaussian or non‐Gaussian. Numerically simulated load histories, as well as loads measured on mountain bikes in special tracks, are analysed to validate the proposed methodology. The presented results also show the correlation between load non‐stationarity and non‐Gaussianity.
A critical investigation of techniques for stress determination and equivalent static analysis in fatigue life estimation
Authors: GROVÉ A. P. , VAN TONDER F. , HEYNS P. S. 
Published: October 2007

ABSTRACTThis study entails the fatigue analysis of a complex plate‐like structure subjected to random loading. The stress and fatigue life assessment is performed by means of experimental strain gauge measurements, finite element analysis and a quasi‐static fatigue assessment procedure known as the fatigue equivalent static load (FESL) methodology. Firstly, the integrity of shell elements for accurately capturing the stiffness properties and stress distribution in the vicinity of welds is investigated. Furthermore, the stress response of the structure to random dynamic loading is investigated and validated in terms of its suitability for assessment by the FESL methodology. Nominal stress and hot‐spot stress fatigue life predictions are made, based on measurements as well as the FESL procedure. The viability and integrity of the FESL methodology is critically assessed after which the actual fatigue life of the structure under particular loading conditions is determined for comparison.
A high‐cycle fatigue accumulation model based on electrical resistance for structural steels
Authors: SUN B. , YANG L. , GUO Y. 
Published: October 2007

ABSTRACTFor high‐cycle fatigue of metals, the DC electrical resistance is a more sensitive parameter to the initiation of micro‐cracks during the irreversible fatigue damage accumulation process. This implies that the electrical resistance is a suitable parameter that can be consistent with the fatigue damage physical mechanism. The relation between the ratio of electrical resistance changes and the cyclic fraction of the fatigue specimen may reasonably represent deterioration in mechanical properties of structural steels during the high‐cycle fatigue process. The high‐cycle fatigue damage accumulation model based on electrical resistance for structural steels was proposed. The model was verified by some experimental data for three structural steels; normalized 45C steel, 20 Mn steel and 16 Mn steel, and good agreement was obtained. The corresponding fatigue lifetime on the basis of the electrical resistance model was also performed. The results show that the approach to fatigue lifetime prediction and failure based on the electrical resistance is a good non‐destructive technique.
Involvement of astroglial ceramide in palmitic acid‐induced Alzheimer‐like changes in primary neurons
Authors: Patil Sachin , Melrose Joseph , Chan Christina 
Published: October 2007

AbstractA high‐fat diet has been shown to significantly increase the risk of the development of Alzheimer's disease (AD), a neurodegenerative disease histochemically characterized by the accumulation of amyloid beta (Aβ) protein in senile plaques and hyperphosphorylated tau in neurofibrillary tangles. Previously, we have shown that saturated free fatty acids (FFAs), palmitic and stearic acids, caused increased amyloidogenesis and tau hyperphosphorylaion in primary rat cortical neurons. These FFA‐induced effects observed in neurons were found to be mediated by astroglial FFA metabolism. Therefore, in the present study we investigated the basic mechanism relating astroglial FFA metabolism and AD‐like changes observed in neurons. We found that palmitic acid significantly increased de‐novo synthesis of ceramide in astroglia, which in turn was involved in inducing both increased production of the Aβ protein and hyperphosphorylation of the tau protein. Increased amyloidogenesis and hyperphoshorylation of tau lead to formation of the two most important pathophysiological characteristics associated with AD, Aβ or senile plaques and neurofibrillary tangles, respectively. In addition to these pathophysiological changes, AD is also characterized by certain metabolic changes; abnormal cerebral glucose metabolism is one of the distinct characteristics of AD. In this context, we found that palmitic acid significantly decreased the levels of astroglial glucose transporter (GLUT1) and down‐regulated glucose uptake and lactate release by astroglia. Our present data establish an underlying mechanism by which saturated fatty acids induce AD‐associated pathophysiological as well as metabolic changes, placing ‘astroglial fatty acid metabolism’ at the center of the pathogenic cascade in AD.
Differential increase of extracellular dopamine and serotonin in the ‘prefrontal cortex’ and striatum of pigeons during working memory
Authors: Karakuyu Dilek , Herold Christina , Güntürkün Onur , Diekamp Bettina 
Published: October 2007

AbstractMonoamines, such as dopamine (DA) and serotonin (5‐HT), play a central role in the modulation of cognitive processes at the forebrain level. Experimental and clinical studies based on dopaminergic pathology, depletion or medication indicate that DA, in particular, is involved in working memory (WM). However, it is unclear whether DA is indeed related to WM, whether its function is specific to the prefrontal cortex (PFC), and whether other modulators, such as 5‐HT, might have similar functions. Therefore, the aims of this study were threefold. First, we analysed whether increased prefrontal DA release is related to WM in general or only to its short‐term memory component. Second, we examined whether the DA release during cognitive tasks is specific to prefrontal areas or also occurs in the striatum. Third, we analysed whether prefrontal or striatal 5‐HT release accompanies working and short‐term memory. We approached these questions by using in vivo microdialysis to analyse the extracellular DA and 5‐HT release in the pigeons' ‘PFC’ and striatum during matching‐to‐sample tasks with or without a delay. Here, we show that DA has no unitary function but is differentially released during working as well as short‐term memory in the pigeons' ‘prefrontal’ cortex. Striatal DA shows an increased efflux only during WM that involves a delay component. WM is also accompanied by a ‘prefrontal’ but not a striatal release of 5‐HT, whose efflux pattern is thus partly different to that of DA. Our findings thus show a triple dissociation between transmitters, structures and tasks within the avian ‘prefronto’‐striatal system.
Excitotoxicity mediated by non‐NMDA receptors causes distal axonopathy in long‐term cultured spinal motor neurons
Authors: King A.E. , Dickson T.C. , Blizzard C.A. , Foster S.S. , Chung R.S. , West A.K. , Chuah M.I. , Vickers J.C. 
Published: October 2007

AbstractExcitotoxicity has been implicated as a potential cause of neuronal degeneration in amyotrophic lateral sclerosis (ALS). It has not been clear how excitotoxic injury leads to the hallmark pathological changes of ALS, such as the abnormal accumulation of filamentous proteins in axons. We have investigated the effects of overactivation of excitatory receptors in rodent neurons maintained in long‐term culture. Excitotoxicity, mediated principally via non‐N‐methyl‐d‐aspartate (NMDA) receptors, caused axonal swelling and accumulation of cytoskeletal proteins in the distal segments of the axons of cultured spinal, but not cortical, neurons. Axonopathy only occurred in spinal neurons maintained for 3 weeks in vitro, indicating that susceptibility to axonal pathology may be related to relative maturity of the neuron. Excitotoxic axonopathy was associated with the aberrant colocalization of phosphorylated and dephosphorylated neurofilament proteins, indicating that disruption to the regulation of phosphorylation of neurofilaments may lead to their abnormal accumulation. These data provide a strong link between excitotoxicity and the selective pattern of axonopathy of lower motor neurons that underlies neuronal dysfunction in ALS.
Different effects of monocarboxylates on neuronal survival and β‐amyloid toxicity
Authors: Wang XiaoNan , Takata Toshihiro , Sakurai Takashi , Yokono Koichi 
Published: October 2007

AbstractGlucose is a principal metabolic fuel in the central nervous system, but, when glucose is unavailable, the brain can utilize alternative metabolic substrates such as monocarboxylates to sustain brain functions. This study examined whether the replacement of glucose with monocarboxylates (particularly pyruvate and lactate) had an equivalent effect of glucose on neuronal survival in rat hippocampal organotypic slice cultures, or ameliorate the neurotoxicity induced by amyloid β‐peptide (Aβ). The possible mechanism was also explored. We found that pyruvate and lactate alone increased cell death in the hippocampal slice cultures at 24 and 48 h. Supplementation of glucose‐containing culture media and Aβ‐treated culture media with pyruvate, but not lactate, attenuated cell death as strong as with trolox, known as a reactive oxygen species scavenger, and niacinamide, an NAD+ precursor, and this protective effect was reversed by α‐cyano‐4‐hydroxycinnamic acid. Pyruvate significantly increased the aconitase activity and the NAD+ levels in the hippocampal slices in the presence of Aβ, but did not maintain the ATP levels. Our results indicate that pyruvate and lactate alone cannot replace glucose as an alternative energy source to preserve the neuronal viability in the hippocampal slice cultures. Pyruvate, in the presence of glucose, improves neuronal survival in the hippocampal slice cultures and also protects neurons against Aβ‐induced cell death in which mitochondrial NAD(P) redox status may play a central role.
Primary and secondary neural networks of auditory prepulse inhibition: a functional magnetic resonance imaging study of sensorimotor gating of the human acoustic startle response
Authors: Campbell Linda E. , Hughes Matthew , Budd Timothy W. , Cooper Gavin , Fulham W. Ross , Karayanidis Frini , Hanlon Mary‐Claire , Stojanov Wendy , Johnston Patrick , Case Vanessa , Schall Ulrich 
Published: October 2007

AbstractFeedforward inhibition deficits have been consistently demonstrated in a range of neuropsychiatric conditions using prepulse inhibition (PPI) of the acoustic startle eye‐blink reflex when assessing sensorimotor gating. While PPI can be recorded in acutely decerebrated rats, behavioural, pharmacological and psychophysiological studies suggest the involvement of a complex neural network extending from brainstem nuclei to higher order cortical areas. The current functional magnetic resonance imaging study investigated the neural network underlying PPI and its association with electromyographically (EMG) recorded PPI of the acoustic startle eye‐blink reflex in 16 healthy volunteers. A sparse imaging design was employed to model signal changes in blood oxygenation level‐dependent (BOLD) responses to acoustic startle probes that were preceded by a prepulse at 120 ms or 480 ms stimulus onset asynchrony or without prepulse. Sensorimotor gating was EMG confirmed for the 120‐ms prepulse condition, while startle responses in the 480‐ms prepulse condition did not differ from startle alone. Multiple regression analysis of BOLD contrasts identified activation in pons, thalamus, caudate nuclei, left angular gyrus and bilaterally in anterior cingulate, associated with EMG‐recorded sensorimotor gating. Planned contrasts confirmed increased pons activation for startle alone vs 120‐ms prepulse condition, while increased anterior superior frontal gyrus activation was confirmed for the reverse contrast. Our findings are consistent with a primary pontine circuitry of sensorimotor gating that interconnects with inferior parietal, superior temporal, frontal and prefrontal cortices via thalamus and striatum. PPI processes in the prefrontal, frontal and superior temporal cortex were functionally distinct from sensorimotor gating.
Methyl sulfides as intermediates in the anaerobic oxidation of methane
Authors: Moran James J. , Beal Emily J. , Vrentas Jennifer M. , Orphan Victoria J. , Freeman Katherine H. , House Christopher H. 
Published: October 2007

SummaryWhile it is clear that microbial consortia containing Archaea and sulfate‐reducing bacteria (SRB) can mediate the anaerobic oxidation of methane (AOM), the interplay between these microorganisms remains unknown. The leading explanation of the AOM metabolism is ‘reverse methanogenesis’ by which a methanogenesis substrate is produced and transferred between species. Conceptually, the reversal of methanogenesis requires low H2 concentrations for energetic favourability. We used 13C‐labelled CH4 as a tracer to test the effects of elevated H2 pressures on incubations of active AOM sediments from both the Eel River basin and Hydrate Ridge. In the presence of H2, we observed a minimal reduction in the rate of CH4 oxidation, and conclude H2 does not play an interspecies role in AOM. Based on these results, as well as previous work, we propose a new model for substrate transfer in AOM. In this model, methyl sulfides produced by the Archaea from both CH4 oxidation and CO2 reduction are transferred to the SRB. Metabolically, CH4 oxidation provides electrons for the energy‐yielding reduction of CO2 to a methyl group (‘methylogenesis’). Methylogenesis is a dominantly reductive pathway utilizing most methanogenesis enzymes in their forward direction. Incubations of seep sediments demonstrate, as would be expected from this model, that methanethiol inhibits AOM and that CO can be substituted for CH4 as the electron donor for methylogenesis.
Sewage and community shower drains are environmental reservoirs of Fusarium solani species complex group 1, a human and plant pathogen
Authors: Mehl H. L. , Epstein L. 
Published: October 2007

SummaryIn two recent studies, clinical isolates in the Fusarium solani species complex (FSSC) were sequenced; one of the most common lineages was FSSC Group 1 (FSSC 1), a phylogenetic species that is synonymous with F. solani f. sp. cucurbitae race 2, a pathogen of cucurbit fruits. FSSC 1 was also identified in sink and shower drains in two hospitals. The environmental sources of FSSC 1 are important for understanding the epidemiology of both human and plant diseases caused by this organism. FSSC 1 was detected in sewage influent at all six tested urban wastewater treatment plants (WWTPs) in California with a concentration ranging from 75 to 413 colony‐forming units (cfu) l−1, a mean of 246 ± 52 cfu l−1 and a median of 254 cfu l−1. During the treatment process, the concentration of FSSC 1 in the solid and liquid fractions diminished. FSSC 1 was detected in five and six of 14 community shower drains by culturing and polymerase chain reaction, respectively, whereas FSSC DNA was detected in all drains. FSSC accounted for 17 ± 6% (n = 14) of the total fungal DNA in the drains. FSSC 1 was rarely isolated from post‐harvest cucurbit fruits and was not found in cucurbit fields in California.
Ectopic expression of a wood‐abundant expansin PttEXPA1 promotes cell expansion in primary and secondary tissues in aspen
Authors: Gray‐Mitsumune Madoka , Blomquist Kristina , McQueen‐Mason Simon , Teeri Tuula T. , Sundberg Björn , Mellerowicz Ewa J. 
Published: October 2007

SummaryExpansins are primary agents inducing cell wall extension, and are therefore obvious targets in biotechnological applications aimed at the modification of cell size in plants. In trees, increased fibre length is a goal of both breeding and genetic engineering programmes. We used an α‐expansin PttEXPA1 that is highly abundant in the wood‐forming tissues of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) to evaluate its role in fibre elongation and wood cell development. PttEXPA1 belongs to Subfamily A of α‐expansins that have conserved motifs at the N‐ and C‐termini of the mature protein. When PttEXPA1 was over‐expressed in aspen, an extract of the cell wall‐bound proteins of the transgenic plants exhibited an increased expansin activity on cellulose–xyloglucan composites in vitro, indicating that PttEXPA1 is an active expansin. The transgenic lines exhibited increased stem internode elongation and leaf expansion, and larger cell sizes in the leaf epidermis, indicating that PttEXPA1 protein is capable of increasing the growth of these organs by enhancing cell wall expansion in planta. Wood cell development was also modified in the transgenic lines, but the effects were different for vessel elements and fibres, the two main cell types of aspen wood. PttEXPA1 stimulated fibre, but not vessel element, diameter growth, and marginally increased vessel element length, but did not affect fibre length. The observed differences in responsiveness to expansin of these cell types are discussed in the light of differences in their growth strategies and cell wall composition.
Impact of Beijing Olympic‐related Investments on Regional Economic Growth of China: Interregional Input–Output Approach*
Authors: Zhang Yaxiong , Zhao Kun 
Published: October 2007

Using the interregional input–output model, the present paper analyzes the impact of Olympic‐related investments on the economic development of Beijing and its surrounding areas, as well as the rest of China. The interregional input–output model provides a satisfactory simulation and analysis of Olympic‐related investments that are implemented in Beijing and other areas and their spillover effects on other regions. We estimate that from 2002 to 2007, Olympic‐related investments will add 2.02, 0.23 and 0.09 percent annually to gross regional products of Beijing, its surrounding areas and the rest of China, respectively.
Who is Better Off from Trade Liberalization? An Experience from Urban China*
Authors: He Yin 
Published: October 2007

Empirical studies have found that the skill wage gap (difference between wages earned by skilled and unskilled workers) narrowed in the case of the ‘Four Asian Dragons’ as they underwent trade liberalization during the 1960s and 1970s, whereas the gap widened in most of the Latin American countries after they liberalized their economies in the 1980s. China's integration into the world economy since 1978 has been used to explain this phenomenon, but few formal studies have been carried out in China regarding the effects of trade liberalization on the skill wage gap because of the limited availability of data. The present study uses unique household surveys conducted in ten provinces of China in 1988 and 1995 to study this issue. Results show that trade liberalization that occurred in China between 1988 and 1995 was responsible for an average increase of 28.73 yuan (approximately 20 percent of the total increase) in average monthly wages. However, trade liberalization significantly widened the urban skill wage gap in China by introducing an increase in income only for those who had 13 years or more of education (at least junior high school graduates). Interestingly, import liberalization also only benefited those who had more than 9 years of schooling; whereas export liberalization brought wage increases for people with 7–12 years of education. Finally, those with specific production skills from technical schools, rather than those with several years of general education, were mostly favored in the labor market in China between 1988 and 1995.
ON THE STRONG LAW OF LARGE NUMBERS UNDER REARRANGEMENTS FOR SEQUENCES OF BLOCKWISE ORTHOGONAL RANDOM ELEMENTS IN BANACH SPACES
Authors: Van Quang Nguyen , Van Thanh Le 
Published: October 2007

SummaryThe condition of the strong law of large numbers is obtained for sequences of random elements in type p Banach spaces that are blockwise orthogonal. The current work extends a result of Chobanyan & Mandrekar (2000)[On Kolmogorov SLLN under rearrangements for orthogonal random variables in a B‐space. J. Theoret. Probab. 13, 135–139.] Special cases of the main results are presented as corollaries, and illustrative examples are provided.
Distress in children with learning disabilities at a respite unit: perspectives on their experiences
Authors: Radcliffe Jonathan J. L. , Turk Vicky 
Published: October 2007

Accessible summary

This research was done in London with children who went to a respite unit.
All the children had learning disabilities.
Children go to respite units to give their parents a rest.
Some children like going to respite. Other children get very unhappy at respite and miss their home badly.
It can be difficult to tell if children do not like going when they cannot talk very much.
Teachers, respite staff and parents had different opinions about whether the children like going.
We think it is very important to try to find out whether the children get very unhappy so people can try to make things better for them.

SummaryNumerous studies have investigated the benefits of respite to families with a disabled child. Far fewer have examined the effects on the child and none have systematically compared information about this from different sources. Reports of behavioural reactions and views on distress were gathered from parents, teachers and respite staff. Children were also asked for their views. Over half the children (54%) were reported to show medium or strong negative reactions lasting for 1 or more days by a parent or teacher. Reported reactions varied widely between home and school and no concordance was found between parents, teachers and respite staff groups regarding distress. Some children’s views differed from those of their parent or teacher. The findings highlight the extent of differences in perspectives and suggest the need for greater awareness of the possible distress to children attending respite. This is discussed in relation to factors such as the potential conflict of interests between parents and children, communication and behavioural difficulties, and the context in which the child is observed.
Evidence for a Founder Effect of the Germline Fumarate Hydratase Gene Mutation R58P causing Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC)
Authors: Heinritz W. , Paasch U. , Sticherling M. , Wittekind C. , Simon J.C. , Froster U.G. , Renner R. 
Published: October 2007

SummaryWe report on the results of clinical investigation, pedigree analysis, mutation screening and haplotyping in a family with the syndrome of multiple cutaneous and uterine leiomyomas (MCUL1) and a germline missense mutation (R58P) in the fumarate hydratase gene (FH). We provide evidence for a founder effect for the identified mutation and distant relationship of our family to another familial case of MCUL1 associated with renal cell cancer, which was recently published with the same mutation.