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Different Durations (different + duration)

Distribution by Scientific Domains

Medical Sciences	37%
Life Sciences	17%
Chemistry	13%
Polymers and Materials Science	10%
Earth and Environmental Science	10%

Selected Abstracts

A locus for an auditory processing deficit and language impairment in an extended pedigree maps to 12p13.31-q14.3

GENES, BRAIN AND BEHAVIOR, Issue 6 2010
L. Addis
Despite the apparent robustness of language learning in humans, a large number of children still fail to develop appropriate language skills despite adequate means and opportunity. Most cases of language impairment have a complex etiology, with genetic and environmental influences. In contrast, we describe a three-generation German family who present with an apparently simple segregation of language impairment. Investigations of the family indicate auditory processing difficulties as a core deficit. Affected members performed poorly on a nonword repetition task and present with communication impairments. The brain activation pattern for syllable duration as measured by event-related brain potentials showed clear differences between affected family members and controls, with only affected members displaying a late discrimination negativity. In conjunction with psychoacoustic data showing deficiencies in auditory duration discrimination, the present results indicate increased processing demands in discriminating syllables of different duration. This, we argue, forms the cognitive basis of the observed language impairment in this family. Genome-wide linkage analysis showed a haplotype in the central region of chromosome 12 which reaches the maximum possible logarithm of odds ratio (LOD) score and fully co-segregates with the language impairment, consistent with an autosomal dominant, fully penetrant mode of inheritance. Whole genome analysis yielded no novel inherited copy number variants strengthening the case for a simple inheritance pattern. Several genes in this region of chromosome 12 which are potentially implicated in language impairment did not contain polymorphisms likely to be the causative mutation, which is as yet unknown. [source]

Nitrogen biomarkers and their fate in soil,

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2003
Wulf Amelung
Abstract More than 90,% of the nitrogen (N) in soils can be organically bound, but the mechanisms and rates by which it is cycled have eluded researchers. The objective of this research was to contribute to a better understanding of the origin and transformation of soil organic N (SON) by using amino sugars and the enantiomers of amino acids as markers for microbial residues and/or aging processes. Studied samples presented here comprised (1) soil transects across different climates, (2) arable soils with different duration of cropping, and (3) radiocarbon-dated soil profiles. The results suggested that increased microbial alteration of SON temporarily results in a sequestration of N in microbial residues, which are mineralized at later stages of SON decomposition. Microorganisms increasingly sequestered N within intact cell wall residues as frost periods shortened. At a mean annual temperature above 12,15,°C, these residues were mineralized, probably due to limitations in additional substrates. Breaking the grassland for cropping caused rapid SON losses. Microbial residues were decomposed in preference to total N, this effect being enhanced at higher temperatures. Hence, climate and cultivation interactively affected SON dynamics. Nevertheless, not all SON was available to soil microorganisms. In soil profiles, L-aspartic acid and L-lysine slowly converted into their D-form, for lysine even at a similar rate in soils of different microbial activity. Formation of D-aspartate with time was, therefore, induced by microorganisms while that of D-lysine was not. The racemization of the two amino acids indicates that SON not available to microorganisms ages biotically and abiotically. In native soils, the latter is conserved for centuries, despite N deficiency frequently occurring in living terrestrial environments. Climate was not found to affect the fate of old protein constituents in surface soil. When native grassland was broken for cropping, however, old SON constituents had become available to microorganisms and were degraded. Stickstoff-Biomarker und ihre Dynamik im Boden Über 90,% des Stickstoffs im Boden können organisch gebunden sein. Um zu einem besseren Verständnis der Norg -Dynamik im Boden beitragen zu können, analysierte ich Aminozucker und Aminosäure-Enantiomere als Marker für mikrobielle N-Rückstände und/oder Alterungsprozesse von Norg im Boden. Das hier vorgestellte Untersuchungsmaterial umfasste (1) Bodentransekte entlang unterschiedlicher Klimate, (2) Ackerböden mit verschiedener Nutzungsdauer und (3) 14C-datierte Bodenprofile. Die Ergebnisse zeigten, dass mit fortschreitender Umwandlung des Norg mikrobielle N-Rückstände nur vorübergehend im Boden akkumulieren, da sie in späteren Abbauphasen wieder mineralisiert werden. Mikroorganismen bauten zunehmend N in intakte Zellwandrückstände ein, wenn sich die Frostperioden verkürzten. Bei einer Jahresmitteltemperatur über 12,15,°C sank der Beitrag mikrobieller Rückstände zum N-Gehalt, vermutlich weil Mikroorganismen diese mangels anderer Substrate verstärkt mineralisierten. Umbrüche von Gras- zu Ackerland führten zu raschen N-Verlusten. Mikrobielle N-Rückstände wurden bevorzugt abgebaut, ein Effekt, den höhere Temperaturen verstärkten. Demnach steuerte das Klima die Intensität von Nutzungseffekten auf die Norg -Dynamik. Doch nicht der gesamte Norg war für Mikroorganismen zugänglich. Der D-Gehalt von Asparaginsäure und Lysin nahm mit steigendem Alter der organischen Bodensubstanz zu, Lysin racemisierte in den verschiedenen Böden sogar mit gleicher Geschwindigkeit. Anders als die Bildung von D-Asparaginsäure wurde die von Lysin also nicht durch Mikroorganismen beeinflusst. Die Racemisierung der beiden Aminosäuren deutet deshalb darauf hin, dass nicht-bioverfügbare Norg -Bestandteile biotisch und abiotisch im Boden altern. Klimaeinwirkungen auf den Verbleib alter Proteinrückstände ließen sich nicht feststellen. Mit Umbruch von Gras- zu Ackerland erhielten Mikroorganismen allerdings Zugang zu alten Norg -Verbindungen und bauten diese ab. [source]

Post-thrombotic syndrome, recurrence, and death 10 years after the first episode of venous thromboembolism treated with warfarin for 6 weeks or 6 months

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2006
S. SCHULMAN
Summary.,Background: The influence of the duration of anticoagulant therapy after venous thromboembolism (VTE) on the long-term morbidity and mortality is unclear. Aim: To investigate the long-term sequelae of VTE in patients randomized to different duration of secondary prophylaxis. Methods: In a multicenter trial comparing secondary prophylaxis with vitamin K antagonists for 6 weeks or 6 months, we extended the originally planned 2 years follow-up to 10 years. The patients had annual visits and at the last visit clinical assessment of the post-thrombotic syndrome (PTS) was performed. Recurrent thromboembolism was adjudicated by a radiologist, blinded to treatment allocation. Causes of death were obtained from the Swedish Death Registry. Results: Of the 897 patients randomized, 545 could be evaluated at the 10 years follow-up. The probability of developing severe PTS was 6% and any sign of PTS was seen in 56.3% of the evaluated patients. In multivariate analysis, old age and signs of impaired circulation at discharge from the hospital were independent risk factors at baseline for development of PTS after 10 years. Recurrent thromboembolism occurred in 29.1% of the patients with a higher rate among males, older patients, those with permanent triggering risk factor , especially with venous insufficiency at baseline , signs of impaired venous circulation at discharge, proximal deep vein thrombosis, or pulmonary embolism. Death occurred in 28.5%, which was a higher mortality than expected with a standardized incidence ratio (SIR) of 1.43 (95% CI 1.28,1.58), mainly because of a higher mortality than expected from cancer (SIR 1.83; 95% CI 1.44,2.23) or from myocardial infarction or stroke (SIR 1.28; 95% CI 1.00,1.56). The duration of anticoagulation did not have a statistically significant effect on any of the long-term outcomes. Conclusion: The morbidity and mortality during 10 years after the first episode of VTE is high and not reduced by extension of secondary prophylaxis from 6 weeks to 6 months. A strategy to reduce recurrence of VTE as well as mortality from arterial disease is needed. [source]

Positron annihilation study of recrystallization behaviour in Zr2.5%Nb alloy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2009
S. Mulki
Abstract In CANDU reactors Zr 2.5%Nb alloy is used as pressure tube material due to low neutron absorption cross section, a high resistance to corrosion in water, high strength and good creep resistance. The two phase alloy consists of ,-fcc and ,-bcc. The recrystallization behavior of Zr2.5Nb strongly depends on morphology and distribution of second phase. In this study, the material was deformed to 60% and then was recrystallized in , + , region for different duration (i.e. 2 minutes to 14 days at 700 °C). The recrystallized microstructure was characterized by Orientation Imaging Microscopy (OIM). The evolution of microstructure was examined by Positron Lifetime Spectroscopy and Doppler Broadening measurement for each heat treated samples. Results from positron annihilation studies and other microstructural examination have been used to rationalize the recrystallization aspects, defects and ,-phase distribution. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

An evidence-based appraisal of splinting luxated, avulsed and root-fractured teeth

DENTAL TRAUMATOLOGY, Issue 1 2008
Bill Kahler
For this systematic review of splinting of teeth that have been luxated, avulsed or root-fractured, the clinical PICO question is (P) what are splinting intervention decisions for luxated, avulsed and root-fractured teeth (I) considering that the splinting intervention choice may include (i) no splinting, (ii) rigid or functional splinting for the different types of trauma and (iii) different durations of the splinting period (C) when comparing these splinting choices for the different types of trauma and their effect on (O) healing outcomes for the teeth. A keyword search of PubMed was used. Reference lists from identified articles and dental traumatology texts were also appraised. The inclusion criterion for this review was either a multivariate analysis or controlled stratified analyses as many variables have the potential to confound the assessment and evaluation of healing outcomes for teeth that have been luxated, avulsed or root-fractured. A positive statistical test is not proof of a causal conclusion, as a positive statistical relationship can arise by chance, and so this review also appraises animal studies that reportedly explain biological mechanisms that relate to healing outcomes of splinted teeth. The clinical studies were ranked using the ,Centre of Evidence-based Medicine' categorization (levels 1,5). All 12 clinical studies selected were ranked as level 4. The studies generally indicate that the prognosis is determined by the type of injury rather than factors associated with splinting. The results indicate that the types of splint and the fixation period are generally not significant variables when related to healing outcomes. This appraisal identified difficulties in the design of animal experimentation to correctly simulate some dental injuries. Some of the studies employed rigid splinting techniques, which are not representative of current recommendations. Recommended splinting treatment protocols for teeth that have been luxated, avulsed or root-fractured teeth are formulated on the strength of research evidence. Despite the ranking of these studies in this appraisal as low levels of evidence, these recommendations should be considered ,best practice', a core philosophy of evidence-based dentistry. [source]

Subcellular distribution of zinc in Daphnia magna and implication for toxicity

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010
Wen-Xiong Wang
Abstract We examined the subcellular partitioning of zinc (Zn) in Daphnia magna both under acute and chronic exposures. In the acute Zn toxicity tests, the daphnids were exposed to different Zn concentrations for 48,h or to one lethal concentration (1,000,µg/L) for different durations (time to death for up to 47,h). Significant mortality of daphnids was observed when the newly accumulated Zn concentration reached a threshold level of approximately 40,µg/g wet weight (or 320,µg/g dry wt), approximately 3.5 times higher than the background tissue concentration (92,µg/g dry wt). Chronic exposure (14 d) to Zn resulted in nonobservable effect on survivorship and growth at newly accumulated tissue concentration of over 40,µg/g wet weight. With increasing Zn acute exposure, more Zn was partitioned into the cellular debris fraction, indicating that this fraction was presumably the first targeted site of binding for Zn upon entering the animals. The importance of other subcellular fractions either decreased accordingly or remained comparable. We found that the metal-sensitive fraction (Zn distribution in the organelles and heat-denatured proteins) did not predict the acute Zn toxicity in Daphnia. During chronic exposure, however, no major change of the subcellular partitioning of Zn with increasing Zn exposure was documented. Zinc was mainly found in the organelles and heat-stable protein fractions during chronic exposure, suggesting that any subcellular repartitioning occurred primarily during acute exposure. Metallothioneins were induced upon chronic Zn exposure, but its induction evidently lagged behind the Zn accumulation. Our present study showed that the subcellular fractionation approach could not be readily used to predict the acute and chronic toxicities of Zn in Daphnia. A tissue-based Zn accumulation approach with a threshold Zn tissue concentration was better in predicting acute Zn toxicity. Environ. Toxicol. Chem. 2010; 29:1841,1848. © 2010 SETAC [source]

Long-term clopidogrel administration following severe coronary injury reduces proliferation and inflammation via inhibition of nuclear factor-kappaB and activator protein 1 activation in pigs

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2009
K. Pels
ABSTRACT Background, The optimal duration of clopidogrel treatment following percutaneous coronary intervention (PCI) and the patient population that would benefit most are still unknown. In a porcine coronary injury model, we tested two different durations of clopidogrel treatment on severely or moderately injured arteries and examined the arterial response to injury. To understand the molecular mechanism, we also investigated the effects on transcription factors nuclear factor-kappaB (NF-,B) and activator protein 1 (AP-1). Materials and methods, In 24 cross-bred pigs, one coronary artery was only moderately injured by percutaneous transluminal coronary angioplasty (PTCA) and one coronary artery was severely injured by PTCA and subsequent beta-irradiation (Brachy group). Animals received 325 mg aspirin daily for 3 months and 75 mg clopidogrel daily for either 28 days [short-term (ST) clopidogrel group] or 3 months [long-term (LT) clopidogrel group]. Results, After 3 months, the number of proliferating cells per cross-section differed significantly between ST and LT in both injury groups (PTCAST 90·2 ± 10·3 vs. PTCALT 19·2 ± 4·7, P < 0·05; BrachyST 35·8 ± 8·4 vs. BrachyLT 7·5 ± 2·0, P < 0·05). Similar results were seen for inflammatory cells (CD3+ cells): PTCAST 23·5 ± 3·55 vs. PTCALT 4·67 ± 0·92, P < 0·05; BrachyST 83·17 ± 11·17 vs. BrachyLT 20 ± 4·82, P < 0·05). Long-term administration also reduced the activity of NF-,B and AP-1 by 62,64% and 42,58%, respectively. However, the effects of different durations of clopidogrel administration on artery dimensions were not statistically significant. Conclusions, Regarding inflammation and transcription factor activity at the PCI site, long-term clopidogrel administration is superior to short-term administration, especially in severely injured arteries. Transferring our results to the human situation, patients with more severely diseased arteries may benefit from a prolonged clopidogrel medication after PCI. [source]

Temporal filtering by prefrontal neurons in duration discrimination

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2008
Ken-ichi Oshio
Abstract Neural imaging studies have revealed that the prefrontal cortex (PFC) participates in time perception. However, actual functional roles remain unclear. We trained two monkeys to perform a duration-discrimination task, in which two visual cues were presented consecutively for different durations ranging from 0.2 to 2.0 s. The subjects were required to choose the longer cue. We recorded single-neuron activity from the PFC while the subjects were performing the task. Responsive neurons for the first cue period were extracted and classified through a cluster analysis of firing rate curves. The neuronal activity was categorized as phasic, ramping and sustained patterns. Among them, the phasic activity was the most prevailing. Peak time of the phasic activity was broadly distributed about 0.8 s after cue onset, leading to a natural assumption that the phasic activity was related to cognitive processes. The phasic activity with constant delay after cue onset might function to filter current cue duration with the peak time. The broad distribution of the peak time would indicate that various filtering durations had been prepared for estimating C1 duration. The most frequent peak time was close to the time separating cue durations into long and short. The activity with this peak time might have had a role of filtering in attempted duration discrimination. Our results suggest that the PFC contributes to duration discrimination with temporal filtering in the cue period. [source]

THE LOCI OF EVOLUTION: HOW PREDICTABLE IS GENETIC EVOLUTION?

EVOLUTION, Issue 9 2008
David L. Stern
Is genetic evolution predictable? Evolutionary developmental biologists have argued that, at least for morphological traits, the answer is a resounding yes. Most mutations causing morphological variation are expected to reside in the cis -regulatory, rather than the coding, regions of developmental genes. This "cis -regulatory hypothesis" has recently come under attack. In this review, we first describe and critique the arguments that have been proposed in support of the cis -regulatory hypothesis. We then test the empirical support for the cis -regulatory hypothesis with a comprehensive survey of mutations responsible for phenotypic evolution in multicellular organisms. Cis -regulatory mutations currently represent approximately 22% of 331 identified genetic changes although the number of cis -regulatory changes published annually is rapidly increasing. Above the species level, cis -regulatory mutations altering morphology are more common than coding changes. Also, above the species level cis -regulatory mutations predominate for genes not involved in terminal differentiation. These patterns imply that the simple question "Do coding or cis -regulatory mutations cause more phenotypic evolution?" hides more interesting phenomena. Evolution in different kinds of populations and over different durations may result in selection of different kinds of mutations. Predicting the genetic basis of evolution requires a comprehensive synthesis of molecular developmental biology and population genetics. [source]

Detection of trends in annual extreme rainfall

HYDROLOGICAL PROCESSES, Issue 18 2003
Kaz Adamowski
Abstract Information on intensity,duration,frequency of rainfall is commonly required for a variety of hydrologic applications. In this study, trends are estimated for different durations of annual extreme rainfall using the regional average Mann,Kendall S trend test. The method of L-moments was employed to delineate homogeneous regions. The trend test was modified to account for observed autocorrelation, and a bootstrap methodology was used to account for the observed spatial correlation. Numerical analysis was performed on 44 rainfall stations from the province of Ontario, Canada, for a 20 year time frame. This was done using data from homogeneous regions established using the L-moments procedure for the annual maximum observations for the following durations: 5, 10, 15 and 30 min, and 1, 2, 6 and 12 h. Depending on different rainfall durations, four or five homogeneous regions were delineated. Based on a 5% significance level, approximately 23% of the regions tested had a significant trend, predominantly for short-duration storms. Serial dependency was observed in 2·3% of data sets and spatial correlation was found in 18% of the regions. The presence of serial and spatial correlation had a significant impact on trend determination. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Influence of water content, time, and temperature on the rheological behavior of polyethylene terephtalate

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
A. M. C. Souza
Abstract In this work, the main factors affecting the rheological behavior of polyethylene terephtalate (PET) in the linear viscoelastic regime (water content, time delay before test, duration of experiment, and temperature) were accessed. Small amplitude oscillatory shear tests were performed after different time delays ranging from 300 to 5000 s for samples with water contents ranging from 0.02 to 0.45 wt %. Time sweep tests were carried out for different durations to explain the changes undergone by PET before and during small amplitude oscillatory shear measurements. Immediately after the time sweep tests, the PET samples were removed from the rheometer, analyzed by differential scanning calorimetry and their molar mass was obtained by viscometry analysis. It was shown that for all the samples, the delay before test and residence time within the rheometer (i.e. duration of experiment) result in structural changes of the PET samples, such as increase or decrease of molar mass, broadening of molar mass distribution, and branching phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbers

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Hsoung-Wei Chou
Abstract Rubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Effect of activation temperature on pore development in activated carbon produced from palm shell

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2003
Wan Mohd Ashri Wan Daud
Abstract A series of experiments were conducted to investigate the effect of activation temperature on pore development of activated carbon produced from palm shell. Activation of the samples was carried out at 800, 850 and 900,°C for different durations ranging from 10 to 180,min. The samples were characterized using N2 adsorption for evaluation of micropores and the mercury intrusion technique for mesopore and macropore analysis. Within the range of activation temperatures studied, high burn-off products derived from high activation temperatures tend to have larger micropore development. However, an increase in the activation temperature has no remarkable effect on mesopore and macropore development. © 2002 Society of Chemical Industry [source]

RADIO FREQUENCY-HOT WATER DIPS FOR POSTHARVEST CODLING MOTH CONTROL IN APPLES,

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2006
J.D. HANSEN
ABSTRACT A combination radio frequency-hot water dip method was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris (L.) var. domestica (Borkh.) Mansf., which were intended for export to Japan. The apples were initially exposed to 27.12-MHz radio frequency energy at 12 kW for 2.75 min and were then submerged in a range of hot water dips (48,50C) for different durations. Efficacious tests were at 48C for >2 h, at 49C for >50 min and at 50C for >40 min. Fruit quality tests indicated that the best hot water parameters were at 50C for 40 min. Fruit quality after 2 weeks was cultivar dependent where "Fuji" apples tolerated heat treatment better than "Delicious" and "Gala" apples. None of the treated fruits were acceptable after 60 days. Regardless of cultivar, heat treatment resulted in loss of both peel and fresh colors, coupled with reduced firmness and increased external and internal damage. [source]

Ghanaian Cocoa Bean Fermentation Characterized by Spectroscopic and Chromatographic Methods and Chemometrics

JOURNAL OF FOOD SCIENCE, Issue 6 2010
Patrick C. Aculey
Abstract:, Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher,a* and,b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application:, The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies. [source]

Regional dynamics of the fMRI-BOLD signal response to hypoxia-hypercapnia in the rat brain

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2003
Sridhar S. Kannurpatti PhD
Abstract Purpose To examine the regional blood oxygenation level-dependent (BOLD) signal response to rapid changes in arterial oxygen tension. Materials and Methods Functional MR imaging (fMRI) was carried out in five male Sprague-Dawley rats anesthetized with Sodium Pentobarbital. Rats were subjected to different durations of apnea as a rapid, graded, and reversible hypoxic-hypercapnic stimulus. Dynamics of the BOLD signal response were studied on a pixel-by-pixel basis in the cerebral cortex, hippocampus, third ventricle, and thalamus in the rat brain. Results Apnea induced a BOLD signal drop in all the brain regions studied, the magnitude of which increased with longer durations of the stimulus. The signal recovered to preapnic baseline levels after resumption of normal ventilation. Regional variation in the BOLD signal dynamics was observed with the magnitude of the BOLD signal change in the hippocampus being the least, followed by a relatively larger change in the thalamus, cerebral cortex, and third ventricle. The time (t0) for the signal change after the onset of the stimulus was estimated for every pixel. Time delay maps generated show the highest onset time values in the hippocampus followed by the thalamus, cerebral cortex, and third ventricle. Conclusion The regional dynamics of the BOLD signal in the brain in response to apnea may vary depending on the rate of oxygen metabolism in addition to cerebral blood flow (CBF). J. Magn. Reson. Imaging 2003;17:641,647. © 2003 Wiley-Liss, Inc. [source]

Investigating the stimulus-dependent temporal dynamics of the BOLD signal using spectral methods

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2003
Karsten Müller PhD
Abstract Purpose To compare several spectral parameters using different durations of visual hemifield stimulation in order to explore the different temporal behavior of the blood oxygenation-level dependent (BOLD) signal in various brain regions. Materials and Methods Spectral methods were applied to three different groups of subjects with visual stimulation lasting 6, 12, and 30 seconds. Furthermore, diffusion weighting was applied in an interleaved way. The core of the data processing was the computation of the spectral density matrix using the multidimensional weighted covariance estimate. Spectral parameters of coherence and phase shift were computed. Results The correlation between signal changes and phase shifts was dependent on the duration of the visual stimulation. The shorter the duration of visual stimulation, the stronger the correlation between percentage signal change and phase shift. Conclusion The experiments with short and long stimuli differed mainly in the distribution of the activated voxels in the plane of percentage signal change and phase shift. It was revealed that the height of the signal change depends on the phase shift, whereas the diffusion weighting has no influence. J. Magn. Reson. Imaging 2003;17:375,382. © 2003 Wiley-Liss, Inc. [source]

A quality assurance audit: Phase III trial of maximal androgen deprivation in prostate cancer (TROG 96.01)

JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 1 2000
A Steigler
SUMMARY In 1997 the Trans-Tasman Radiation Oncology Group (TROG) performed a quality assurance (QA) audit of its phase III randomized clinical trial investigating the effectiveness of different durations of maximal androgen deprivation prior to and during definitive radiation therapy for locally advanced carcinoma of the prostate (TROG 96.01). The audit reviewed a total of 60 cases from 15 centres across Australia and New Zealand. In addition to verification of technical adherence to the protocol, the audit also incorporated a survey of centre planning techniques and a QA time/cost analysis. The present report builds on TROG's first technical audit conducted in 1996 for the phase III accelerated head and neck trial (TROG 91.01) and highlights the significant progress TROG has made in the interim period. The audit provides a strong validation of the results of the 96.01 trial, as well as valuable budgeting and treatment planning information for future trials. Overall improvements were detected in data quality and quantity, and in protocol compliance, with a reduction in the rate of unacceptable protocol violations from 10 to 4%. Audit design, staff education and increased data management resources were identified as the main contributing factors to these improvements. In addition, a budget estimate of $100 per patient has been proposed for conducting similar technical audits. The next major QA project to be undertaken by TROG during the period 1998,1999 is an intercentre dosimetry study. Trial funding and staff education have been targeted as the key major issues essential to the continued success and expansion of TROG's QA programme. [source]

Contrasting textural record of two distinct metamorphic events of similar P,T conditions and different durations

JOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2005
O. LEXA
Abstract A structural, metamorphic and geochronological study of the Staré M,sto belt implies the existence of two distinct metamorphic events of similar peak P,T conditions (700,800 °C, 8,10 kbar) during the Cambro-Ordovician and the Carboniferous tectonometamorphic events. The hypothesis of two distinct periods of metamorphism was suggested on the basis of structural discordance between an undoubtedly Carboniferous granodiorite sill intrusion and earlier Cambro-Ordovician fabrics of a banded amphibolite complex. The analysis of crystal size distribution (CSD) shows high nucleation density (N0) and low average growth rate (Gt) for Carboniferous mylonitic metagabbros and mylonitic granodiorites. The parameter N0 decreases whereas the quantity Gt increases towards higher temperatures progressively approaching the values obtained from the Cambro-Ordovician banded amphibolite complex. The spatial distribution of amphibole and plagioclase shows intense mechanical mixing for lower-temperature mylonitic metagabbros. In high-temperature mylonites a strong aggregate distribution is developed. Cambro-Ordovician amphibolites unaffected by Carboniferous deformation show a regular to anticlustered spatial distribution resulting from heterogeneous nucleation of individual phases. This pattern, together with CSD, was subsequently modified by the grain growth and textural equilibration controlled by diffusive mass transfer during Carboniferous metamorphism. The differences between the observed textures of the amphibolites are interpreted to be a consequence of the different durations of the Carboniferous and Cambro-Ordovician thermal events. [source]

Daily Meal Timing is Not Necessary for Resetting the Main Circadian Clock by Calorie Restriction

JOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2008
J. Mendoza
In rodents, entrainment and/or resetting by feeding of the central circadian clock, the suprachiasmatic nucleus (SCN), is more efficient when food cues arise from a timed calorie restriction. Because timed calorie restriction is associated with a single meal each day at the same time, its resetting properties on the SCN possibly depend on a combination of meal time-giving cues and hypocaloric conditions per se. To exclude any effect of daily meal timing in resetting by calorie restriction, the present study employed a model of ultradian feeding schedules, divided into six meals with different durations of food access (6 × 8-min versus 6 × 12-min meal schedule) every 4 h over the 24-h cycle. The effects of such an ultradian calorie restriction were evaluated on the rhythms of wheel-running activity (WRA) and body temperature (Tb) in rats. The results indicate that daily/circadian rhythms of WRA and Tb were shifted by a hypocaloric feeding distributed in six ultradian short meals (i.e. 6 × 8-min meal schedule), showing both phase advances and delays. The magnitude of phase shifts was positively correlated with body weight loss and level of day-time behavioural activity. By contrast, rats fed daily with six ultradian meals long enough (i.e. 6 × 12-min meal schedule) to prevent body weight loss, showed only small, if any, phase shifts in WRA and Tb rhythms. The results obtained reveal the potency of calorie restriction to reset the SCN clock without synchronisation to daily meal timing, highlighting functional links between metabolism, calorie restriction and the circadian timing system. [source]

Densification of the PLZT Films Derived from Polymer-Modified Solution by Tailoring Annealing Conditions

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2007
Z. H. Du
The Pb0.91La0.09(Zr0.65,Ti0.35)0.9775O3 films were prepared from the solution containing polyvinylpyrrolidone, with Mw of 360 000. A fast heating rate of 40°C/min was used to heat our samples to temperatures in the range of 550°,750°C for different durations. Both a rapid heating rate and isothermal holding at a proper temperature are found to be essential for obtaining dense and crack-free PLZT films. The TG-DTA and Fourier-transform infrared results indicated that the fast heating rate could keep a certain amount of polyvinylpyrrolidone residues undecomposed to a higher temperature (<700°C), which was found to be beneficial for the densification of the films during subsequent isothermal hold. The possible mechanisms responsible for the enhanced densification have been discussed. In addition, the effects of annealing temperature on the electrical and optical properties were also investigated. [source]

Evaluating the cost of sustained virologic response in naïve chronic hepatitis C patients treated à la carte

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2007
M. BUTI
Summary Background There is a tendency to individualize treatment in chronic hepatitis C patients depending on viral load and rapid clearance of HCV-RNA. Aim To evaluate the cost (,, 2006) per sustained virologic response in naïve patients with therapy à la carte compared with standard combination therapy. Methods A decision analysis model was used to compare standard therapy with peginterferon alpha and ribavirin for 24 weeks for genotype (G) 2/3, and 48 weeks for G1 and therapy à la carte with the same drugs but different durations: G1 high viral load for 48 weeks, G1 low viral load with rapid virologic response for 24 weeks, and without rapid virologic response for 48 weeks, and G2/3 with rapid virologic response for 12 weeks, and without rapid virologic response for 24 weeks. Results Sustained virologic response was similar in both strategies. The cost per successfully treated patient for standard therapy is ,17 812 and for therapy à la carte,12 313. Assuming that 13 309 patients with standard therapy and 14 450 patients with therapy à la carte achieve sustained virologic response, therapy à la carte has an overall cost-saving of ,59.13 million. Conclusion Therapy à la carte is a cost-saving strategy for chronic hepatitis C infection compared to standard therapy, with lower investment requirement per patient to achieve sustained virologic response. [source]

Advanced buffers for AlGaN/GaN HEMT and InGaN/GaN MQW on silicon substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
Y. Dikme
Abstract GaN growth was carried out on silicon (Si) substrates by metalorganic vapor phase epitaxy (MOVPE). A layer structure starting with HT (high-temperature) AlN and containing AlGaN and GaN as interlayers was employed for the subsequent deposition of GaN buffer layers. At first, the influence of the in-situ Al pre-deposition at the process start with different durations was investigated. Each time, the pre-deposition was followed by the same layer sequence and with thin AlGaN and GaN grown on top to form a high electron mobility transistor (HEMT). A significant enhancement could be observed in the properties of the investigated samples by reducing the pre-deposition time from 8 s to 2 s. Based on these results, multiple quantum well structures (MQW) and HEMT were grown on these buffers. For the MQW, the well thickness was increased and a shift to higher wavelengths was observed. The HEMT structures have shown enhanced properties by optimizing the growth temperatures of the top AlGaN layer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A Mouse Model of Hypercholesterolemia-Induced Erectile Dysfunction

THE JOURNAL OF SEXUAL MEDICINE, Issue 4i 2007
Donghua Xie MD
ABSTRACT Introduction., Hypercholesterolemia is one of the most important risk factors for the development of erectile dysfunction (ED) in men. Aim., We employed an established mouse model of hypercholesterolemia. Main Outcome Measures., We test for abnormalities in vasoreactivity in corporal tissue and temporally correlated changes in vasoreactivity with alterations in histology and protein expression. Methods., A total of 150 mice were studied. A total of 100 apolipoprotein-E knockout (ApoE,/,) mice were fed a 1.25% cholesterol diet for 2, 4, 8, and 12 weeks (N = 25/group), while a group of ApoE,/, and wild-type Bl-6 mice were fed a normal diet. The study was terminated, and all mice were harvested at 22 weeks of age for vasoreactivity, histology, and protein studies from corporal tissues. Dose,response curves were generated to evaluate endothelium-dependent and endothelium-independent vasoreactivity, ex vivo. The contents of endothelial cells, smooth muscle cells, and smooth muscle/collagen ratio were assessed by immunohistochemistry staining or Masson staining. Level of cyclic guanosine monophosphate (cGMP) was detected by enzyme immunoassay assay. Levels of phosphorylated endothelial nitric oxide synthase (p-eNOS)/total eNOS, neuronal nitric oxide synthase (nNOS), and cyclic GMP-dependent kinase (cGK-1) protein were assessed by Western analysis. Results., Abnormalities in endothelium-dependent and endothelium-independent vasoreactivities, endothelial content, smooth muscle/collagen ratio, p-eNOS phosphorylation at Ser1177 only, nNOS, cGMP, and cGK-1 changed with the different durations of the high-cholesterol diet. Conclusions., These data demonstrate that this mouse model is suitable for investigating aspects of hypercholesterolemic ED. Xie D, Odronic SI, Wu F, Pippen AM, Donatucci CF, and Annex BH. A mouse model of hypercholesterolemia-induced erectile dysfunction. J Sex Med 2007;4:898,907. [source]

Classification of stacking faults and their stepwise elimination during the disorder , order transformation of nickel hydroxide

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2006
T. N. Ramesh
Nickel hydroxide samples obtained by strong alkali precipitation are replete with stacking faults. The local structures of the stacking faults resemble the stacking patterns of different polytypic modifications that are theoretically possible among the layered hydroxides. This resemblance becomes a basis for the classification of stacking faults into different types. Each type of stacking fault produces a characteristic non-uniform broadening of peaks in the X-ray powder diffraction pattern of nickel hydroxide. DIFFaX simulations aid the classification and quantification of stacking faults. Hydrothermal treatment of a poorly ordered nickel hydroxide slurry at different temperatures (338,473,K) and different durations (5,48,h) shows that the stacking faults are removed in a stepwise manner. The as-precipitated sample has 17,20% stacking faults of the 3R2 variety, which evolve into the 2H2 type at 413,K. The 2H2 stacking faults persist up to 443,K. The stacking faults are completely removed only at 473,K. At this temperature an ordered ,-Ni(OH)2 phase is observed. [source]

Randomized, controlled trial of insulin for acute poststroke hyperglycemia

ANNALS OF NEUROLOGY, Issue 5 2010
Michael McCormick MD
Objective Poststroke hyperglycemia is common and is associated with increased risk of death and dependence, but appropriate management remains uncertain. Glucose potassium insulin (GKI) infusion did not benefit patients with moderate poststroke hyperglycemia in a recent trial. Using magnetic resonance imaging (MRI), previous studies identified a relationship between recruitment of ischemic tissue to the final infarct and hyperglycemia, possibly mediated by brain lactic acidosis. Methods We undertook a randomized, placebo-controlled trial of GKI infusion in patients with blood glucose >126mg/dl (7mmol/l) within 24 hours of ischemic stroke. The primary endpoint was infarct growth on MRI between baseline and day 7. Brain lactate concentrations were measured with magnetic resonance spectroscopy. Results Forty patients were randomized, 15 to saline and 25 to GKI infusions of different durations. Capillary blood glucose concentrations were lowered significantly from 6 to 12 hours after GKI initiation. There was no significant difference on any measure of infarct growth between the GKI and saline groups. In a secondary analysis, GKI was associated with significantly greater infarct growth in patients with complete intracranial vessel occlusion compared with controls (p = 0.011 for group,vessel status interaction). Brain lactate levels increased in control subjects, but were significantly lower with GKI infusion. Predominantly asymptomatic hypoglycemia occurred in 76% of GKI-treated subjects. Interpretation GKI infusion within 24 hours of stroke lowered blood glucose and attenuated an increase in brain lactate, but did not affect cerebral infarct growth. Exploratory analysis found that GKI infusion was associated with greater infarct growth in patients with persistent arterial occlusion, and with a high incidence of asymptomatic hypoglycemia. ANN NEUROL 2010;67:570,578 [source]

Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteins

BIOELECTROMAGNETICS, Issue 3 2007
M. Zhadobov
Abstract This article reports experimental results on the influence of low-power millimeter wave (MMW) radiation at 60 GHz on a set of stress-sensitive gene expression of molecular chaperones, namely clusterin (CLU) and HSP70, in a human brain cell line. Selection of the exposure frequency is determined by its near-future applications for the new broadband civil wireless communication systems including wireless local area networks (WLAN) for domestic and professional uses. Frequencies around 60 GHz are strongly attenuated in the earth's atmosphere and such radiations represent a new environmental factor. An exposure system operating in V-band (50,75 GHz) was developed for cell exposure. U-251 MG glial cell line was sham-exposed or exposed to MMW radiation for different durations (1,33 h) and two different power densities (5.4 µW/cm2 or 0.54 mW/cm2). As gene expression is a multiple-step process, we analyzed chaperone proteins induction at different levels. First, using luciferase reporter gene, we investigated potential effect of MMWs on the activation of transcription factors (TFs) and gene promoter activity. Next, using RT-PCR and Western blot assays, we verified whether MMW exposure could alter RNA accumulation, translation, or protein stability. Experimental data demonstrated the absence of significant modifications in gene transcription, mRNA, and protein amount for the considered stress-sensitive genes for the exposure durations and power densities investigated. The main results of this study suggest that low-power 60 GHz radiation does not modify stress-sensitive gene expression of chaperone proteins. Bioelectromagnetics 28:188,196, 2007. © 2006 Wiley-Liss, Inc. [source]

Randomized controlled study of the effects of different durations of light exposure on weight gain by preterm infants in a neonatal intensive care unit

ACTA PAEDIATRICA, Issue 6 2002
N-Y Boo
A randomized controlled study was carried out on 96 preterm infants (>37 wk) with birthweight less than 2000 g admitted to a neonatal intensive care unit. The aim was to compare the weight gain between preterm infants exposed to 12 h cyclical lighting (intensity of light: 78.4 ± 24.7 lux, mean ± SD) and those exposed to a continuously dim environment (5.9 ± 1.9 lux). The exclusion criteria were infants with major congenital malformations or who needed continuous lighting for treatment procedure and care. From day 7 of life until discharge, 50 infants were randomized to receive 12 h cyclical lighting and 46 infants to a continuously dim environment. There was no significant difference in the mean birthweight (12 h lighting vs continuously dim: 1482 vs 1465 g, p= 0.8), mean gestational age (31.6 vs 31.4 wk, p= 0.6), median duration of hospital stay (28.5 vs 28.5 d, p= 0.8), mean age to regain birthweight (13.0 vs 12.9 d, p= 0.3), mean weight gained by day 14 (27.6 vs 36.2 g, p= 1.0), median weight gain per day (11.9 vs 12.2 g, p= 0.9) or median body weight on discharge (1800 vs 1800g, p= 0.4) between the two groups of infants. Conclusion: Exposing preterm infants to either 12 h cyclical lighting or continuously dim environment did not have any significant effect on their weight gain during the neonatal period. [source]