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Various Times (various + time)
Terms modified by Various Times Selected AbstractsPlanform dynamics of the Lower Mississippi RiverEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2006Oliver P. Harmar Abstract This paper presents an analysis of the planform behaviour of the Lower Mississippi River (LMR) using a series of maps and hydrographic surveys covering the period 1765,1975. Data allow analysis at various time and space scales, using fixed and statistically defined reaches, both before and after extensive channel modification. Previous research has interpreted planform change in relation to geomorphological or engineering regime-type analyses of channel length and width for the LMR as a ,single system'. The analysis here is broadly consistent with these approaches, but highlights the importance of meander geometry, in the form of the radius of curvature:width ratio. This neglected factor helps resolve paradoxes relating to observed changes in sediment transport and channel stability. When viewed over smaller time and space scales, analysis of dynamics using fixed reach boundaries reveals a downstream trend in the pattern of planform behaviour, which is closely related to the distribution of valley floor deposits, and which also reflects neotectonic influences. Analysis of changes using statistically determined reach boundaries shows that, over shorter time scales, meander trains are continually formed and modified over a period of approximately 120 years. Zones of more-or-less dynamic behaviour thus move through the LMR. The research also provides a context for 20th century engineering interventions to the river. These have constrained the magnitude of planform adjustment, but also altered the kind of response that is now possible in relation to changes in discharge and sediment load, and as a consequence of internal feedbacks within the LMR system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electrochemical Investigation of Strontium,Metallothionein Interactions , Analysis of Serum and Urine of Patients with OsteoporosisELECTROANALYSIS, Issue 3-5 2009Ivo Fabrik Abstract The main aim of this paper is to study interaction between strontium and metallothionein (MT), and to determine changes in strontium and thiols (MT, reduced glutathione, cysteine, and homocysteine) level in plasma, serum, and urine samples of patients treated with strontium ranelate (SrR). To investigate the interactions between MT and strontium(II) ions, adsorptive transfer stripping technique coupled with differential pulse voltammetry (DPV) the Brdicka reaction was employed. Besides standard Brdicka signals (Co, RS2Co, Cat1, Cat2, Cat3), we observed new signal related to Sr-MT interaction. Further we investigated the effect of various time of interaction, concentration of strontium(II) ions and temperature of supporting electrolyte on Brdicka signals. Optimal time of interaction was 240,s. Under temperature of supporting electrolyte 20,°C, we measured linear dependence of Cat3 signal height on strontium(II) ions concentration. After that we have investigated the possibility of strontium-MT interactions, we were interested in strontium, MT and low molecular mass thiols levels in serum and urine of patients treated with strontium(II) ions to cure osteoporosis. Strontium concentration determined by atomic absorption spectrometry was 55±5,,g/L before and 10,500±1,400,,g/L at the 30th day of SrR administration. Levels of metallothionein in serum ranged from 0.1 to 6.4,,M. Correlation between serum strontium concentration and MT level was determined and correlation coefficient was R=0.93. [source] Dynamic Collapse Mechanisms in Metal Foam ExpansionADVANCED ENGINEERING MATERIALS, Issue 6 2010Dirk Lehmhus Abstract The study provides insight into decomposition of titanium hydride as foaming agent for powder metallurgically produced aluminum foams. Decomposition is characterized using thermal and kinetic analysis, allowing prediction of decomposition reactions. Such predictions are made for various time,temperature cycles, which are experimentally evaluated in parallel foaming experiments. A new explanation of foam collapse is derived from the results, which interprets hints at a maximum gas release rate, limiting maximum expansion, in terms of the existence of a maximum cell wall stretching rate and expanding foam can sustain. Thus a dynamic collapse criterion is added to existing static ones. [source] Aldosterone induces collagen synthesis via activation of extracellular signal-regulated kinase 1 and 2 in renal proximal tubulesNEPHROLOGY, Issue 8 2008GUOSHUANG XU SUMMARY: Aim: Aldosterone plays a crucial role in renal fibrosis by inducing mesangial cell proliferation and promoting collagen synthesis in renal fibroblasts. However, renal proximal tubule involvement in aldosterone-induced collagen synthesis has not yet been identified. The aim of this study was to examine the potential role of aldosterone in collagen expression and its possible mineralocorticoid receptor (MR)-dependent pathway, mediated by activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) in cultured human renal proximal tubular epithelial (HKC) cells. Methods: After HKC cells were stimulated by aldosterone with different concentrations for various time and periods, the gene expression and protein synthesis of collagen I, II, III and IV were measured by real-time polymerase chain reaction and western blot, respectively. ERK1/2 activation, ,-smooth muscle actin (,-SMA), and E-cadherin were also detected by western blot. Results: Aldosterone can increase ERK1/2 phosphorylation of human renal proximal tubular epithelial cells in a time- and dose-dependent manner. Although aldosterone had no effect on collagen I and II expression, it increased expression of ,-SMA and collagen III and IV and decreased that of E-cadherin in HKC cells after 48 h. These effects could be prevented by a ERK pathway inhibitor, U0126, or by a selective MR antagonist, spironolactone. Conclusion: The results suggest that aldosterone plays a pivotal role in tubulointerstitial fibrosis by promoting tubular epithelial,mesenchymal transition and collagen synthesis in proximal tubular cells. The process is MR-dependent, and mediated by ERK1/2 mitogen-activated protein kinase pathway. [source] A systematic study on the stability of UV ink photoinitiators in food simulants using GCPACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2009Zhi-Wei Wang Abstract Several studies have been published on the stability of plastic monomers and additives in food simulants. However, there are practically no published results about the stability of ink components in food simulants. In this work, the stability of two ultraviolet (UV) ink photoinitiators (PIs) in one aqueous and in two substitute fat food simulants was studied under various time,temperature conditions. Furthermore, the addition of the stabilizing agent hydroquinone monomethyl ester (HQMME) in the same conditions was considered as a comparative experiment. The PIs tested were 1-hydroxycyclohexyl-1-phenyl ketone (Irgacure-184) and benzyldimethyl ketal (Irgacure-651). The various test conditions included exposure of 10 days to temperatures of 20, 40 and 60°C for 10% ethanol and 95% ethanol simulants, and exposure of 2 days to temperatures of 20, 40 and 60°C for isooctane. Following exposure to these conditions, the additive samples were analysed. The extracts of samples exposed to various temperature conditions as well as unexposed spiked controls and blanks were analysed by gas chromatography (GC) on a non-polar (5%-phenyl)-methylpolysiloxane capillary column. The results showed that the protective effect of HQMME was not obvious in all test conditions under dark conditions. The Irgacure-184 was quite stable under all test conditions whether the stabilizing agent was added or not. Irgacure-651 was stable almost under all test conditions, except in 10% ethanol at 60°C. The mass spectrum of decomposed product of Irgacure-651 was detected by GC-MS (Mass Spectrum), and the structure of the decomposed product was obtained by mass spectrographic analysis. The method of detection and disposal is also applicable for UV ink PI migration testing from several different paper or paperboard-plastic coating layer materials into the food simulants used in the study. Copyright © 2008 John Wiley & Sons, Ltd. 2008 [source] 3D In-Vivo Optical Skin Imaging for Topographical Quantitative Assessment of Non-Ablative Laser TechnologyDERMATOLOGIC SURGERY, Issue 3 2002Paul M. Friedman MD background. A new method for treating facial rhytides and acne scars with nonablative laser and light source techniques has recently been introduced. Given the inherent limitations of photographic and clinical evaluation to assess subtle changes in rhytides and surface topography, a new noninvasive objective assessment is required to accurately assess the outcomes of these procedures. objective. The purpose of this study was to measure and objectively quantify facial skin using a novel, noninvasive, In-vivo method for assessing three-dimensional topography. This device was used to quantify the efficacy of five treatment sessions with the 1064 nm QS Nd:YAG laser for rhytides and acne scarring, for up to six months following laser treatment. methods. Two subjects undergoing facial rejuvenation procedures were analyzed before and after therapy using a 30-mm, three-dimensional microtopography imaging system (PRIMOS, GFM, Teltow, Germany). The imaging system projects light on to a specific surface of the skin using a Digital Micromirror Device (DMDÔ Texas Instruments, Irving, TX) and records the image with a CCD camera. Skin Surface microtopography is reconstructed using temporal phase shift algorithms to generate three-dimensional images. Measurements were taken at baseline, at various times during the treatment protocol, and then at three and six-month follow-up visits. Silicone skin replicas (FLEXICO, Herts, England) were also made before and after the laser treatment protocol for comparison to In-vivo acquisition. results. Skin roughness decreased by 11% from baseline after three treatment sessions in the wrinkles subject, while a 26% improvement of skin roughness was recorded by 3D In-vivo assessment six months following the fifth treatment session. The subject with acne scarring demonstrated a 33% decrease in roughness analysis after three treatment sessions by 3D In-vivo assessment. A 61% improvement in surface topography was recorded 3-months following the fifth treatment session, which was maintained at the 6-month follow-up. conclusion. Three-dimensional In-vivo optical skin imaging provided a rapid and quantitative assessment of surface topography and facial fine lines following multiple treatment sessions with a 1064-nm QS Nd:YAG laser, correlating with clinical and subjective responses. This imaging technique provided objective verification and technical understanding of nonablative laser technology. Wrinkle depth and skin roughness decreased at the three and six-month follow-up evaluations by 3D In-vivo assessment, indicating ongoing dermal collagen remodeling after the laser treatment protocol. Future applications may include comparison of nonablative laser technology, optimization of treatment regimens, and objective evaluation of other aesthetic procedures performed by dermatologists. [source] The prevalence of methamphetamine and amphetamine abuse in North America: a review of the indicators, 1992,2007DRUG AND ALCOHOL REVIEW, Issue 3 2008JANE CARLISLE MAXWELL PhD Senior Research Scientist Abstract Introduction. This paper reviews epidemiological information about methamphetamine production and use in North America. Methods. Information is drawn from a range of sources, including, but not limited to, historical accounts, peer-reviewed papers, population surveys and large national databases. Results. Methamphetamine and amphetamine use in North America is characterised by geographic variations, with different types of the drug, different routes of administration and different types of users at various times. Unlike some other drug use patterns in North America, the nature of methamphetamine use in Canada, Mexico and the United States has been linked closely in terms of production and supply of the drug. According to their national household surveys, the annual prevalence for ,speed' use in Canada was 0.8% in 2004, 0.3% for ,anfetaminas' and 0.1% for ,metanfetaminas' in Mexico in 2002, and 1.4% for ,stimulants' in the United States in 2006. Discussion. Although the data sources in the three North American countries are not consistent in methodology, terminology or frequency of reporting, all show similar trends. The type of stimulant most used has shifted from non-medical use of pharmaceutical amphetamine to use of powder methamphetamine and then to use of ,ice'. The indicators show the problem is greatest in the western parts of the countries and is moving eastward, but the decreased availability of pseudoephedrine may have a significant impact on the nature of the epidemic in the future. Nevertheless, use of methamphetamine poses a number of risks for users and specialised treatment resources for these various populations are needed. [source] The Effect of Noise in the Emergency DepartmentACADEMIC EMERGENCY MEDICINE, Issue 7 2005Leslie S. Zun MD Abstract Background: It is hypothesized that high ambient noise in the emergency department (ED) adversely affects the ability of the examiner to hear heart and lung sounds. Objective: To determine the ability of various examiners to hear heart tones and lung sounds at the high end of loudness typically found in the ED setting. Methods: The study was divided into two parts. First, sound levels in the ED were measured over various times during the months of January through June 2001, using a sound level monitor. The second part of the study was the determination of the ability to hear heart and lung sounds on a young healthy volunteer using the same Littmann lightweight stethoscope at a predetermined ambient noise level of 90 dB. The results were entered into a database and analyzed using SPSS version 10 (Chicago, IL). Descriptive statistics, analysis of variance, frequencies, and correlation were calculated using this program. Results: Two hundred five sound measurements were taken in the ED during the study period in three locations at various hours. The mean noise level at the nursing station was 57.60 dB, with a minimum of 45.00 dB and a maximum of 70.00 dB. Four of the 104 test subjects (3.8%) were unable to hear the heart tones, and nine of the 104 (8.7%) were unable to hear the lung sounds. Fifty percent (27 of 54) of the test subjects reported diminished lung sounds and eight of 15 (53.3%) reported diminished heart sounds. No significant difference was found between hearing heart sounds and years of experience, age, professional position, and quality of the sound. Significant differences were found between hearing lung sounds and years of experience and professional position, but not with age, gender, and sound quality. Conclusions: This study demonstrated that most of the tested examiners have the ability to hear heart and lung sounds at the extreme of loudness found in one ED. [source] Evaluation of mutant frequencies of chemically induced tumors and normal tissues in ,/cII transgenic miceENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2005Jon C. Mirsalis Abstract Genomic instability has been implicated as an important component in tumor progression. Evaluation of mutant frequencies (MFs) in tumors of transgenic mice containing nontranscribed marker genes should be useful for quantitating mutation rates in tumors as the physiologically inactive transgene provides neither a positive nor a negative selective pressure on the tumor. We have conducted long-term carcinogenicity studies in ,/cII transgenic B6C3F1 mice using a variety of genotoxic and nongenotoxic test agents and have evaluated the mutant frequencies in both tumors and normal tissues from these animals. Mice were administered diethylnitrosamine (DEN) as three intraperitoneal injections of 15 mg/kg; phenobarbital (PB) or oxazepam (OXP) provided ad libitum at 0.1% or 0.25% in the diet, respectively; DEN initiation plus PB in the diet; or urethane (UTH) provided ad libitum at 0.2% in the drinking water. Normal tissues and tumors were isolated at various times over a 2-year period and half of each tissue/tumor was evaluated histopathologically and the other half was evaluated for MF in the cII transgene. Approximately 20 mutants from each of 166 individual tissues (tumor and nontumor) were sequenced to determine whether increases in MF represented unique mutations or were due to clonal expansion. UTH produced significant increases in MF in normal liver and lung. DEN either with or without PB promotion produced significant increases in MF in liver and correction of MF for clonality produced little change in the overall MF in these groups. PB produced a twofold increase in liver MF over controls after 27 weeks of treatment, but a similar increase was not observed with longer dosing times; at later time points, the MF in the PB groups was lower than that of the control group, suggesting that PB is not producing direct DNA damage in the liver. OXP failed to produce an increase in MF over controls, even after 78 weeks of treatment. Selected cases of genomic instability were observed in tumors from all treatments except OXP, with individual liver tumors showing very high MF values even after clonal correction. One rare and interesting finding was noted in a single mouse treated with UTH, where a mammary metastasis had an MF approximately 10-fold greater than the parent tumor, with 75% of the mutations independent, providing strong evidence of genomic instability. There was no clear correlation between tumor phenotype and MF except that pulmonary adenomas generally had higher MFs than normal lung in both genotoxic and nongenotoxic treatment groups. Likewise, there was no correlation between tumor size and MF after correction for clonality. The results presented here demonstrate that individual tumors can show significant genomic instability, with very significant increases in MF that are not attributed to clonal expansion of a single mutant cell. Environ. Mol. Mutagen., 2005. © 2004 Wiley-Liss, Inc. [source] Student perspectives and opinions on their experience at an undergraduate outreach dental teaching centre at Cardiff: a 5-year studyEUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 1 2010C. D. Lynch Abstract Aim:, Outreach teaching is now regarded as a desirable component of undergraduate dental teaching programmes in the UK. A purpose-built undergraduate dental outreach-training centre was opened in Cardiff in 2002. The aim of this paper is to report student perspectives and opinions on their experience at this unit over a 5-year period. Methods:, Final year dental students at Cardiff University were invited to report their comments on the St David's Primary Care Unit at various times during their placement there. Information was recorded for undergraduate students who commenced final year in 2003, 2004, 2005, 2006 and 2007 (n = 257). Results:, After 1 year, the most common favourable aspects reported by students included the availability of a suitably trained nurse for all procedures (n = 191), ready access to helpful/approachable teaching staff (n = 145), and closeness of learning experience to subsequent practice (n = 122). Many students commented on their growing confidence in their own abilities whilst in the unit. Conclusion:, Overwhelmingly, students reported their enthusiasm for training in an outreach teaching unit, preferring it to traditional dental school environments. Inherent in the comments recorded for each student was a sense of growing confidence in their abilities and development of reflective practice. Further work is needed to identify the impact of this form of dental student training on subsequent practices in Vocational Training and independent clinical careers. [source] Nerve growth factor-induced circadian phase shifts and MAP kinase activation in the hamster suprachiasmatic nucleiEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005Gastón A. Pizzio Abstract Circadian rhythms are entrained by light and by several neurochemical stimuli. In hamsters housed in constant darkness, i.c.v. administration of nerve growth factor (NGF) at various times in their circadian cycle produced phase shifts of locomotor activity rhythms that were similar in direction and circadian timing to those produced by brief pulses of light. Moreover, the effect of NGF and light were not additive, indicating signalling points in common. These points include the immediate-early gene c-fos and ERK1/2, a component of the mitogen-activated protein kinases (MAPK) family. NGF activates c-FOS and ERK1/2-MAPK in the suprachiasmatic nuclei, the site of a circadian clock in mammals, when administered during the subjective night but not during the day. The effect of NGF on ERK1/2 activation was not inhibited by the administration of MK-801, a glutamate/NMDA receptor antagonist. These results suggest that NGF, acting through MAPK activation, plays a role in photic entrainment of the mammalian circadian clock. [source] Influence of arbuscular mycorrhizal mycelial exudates on soil bacterial growth and community structureFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007Jonas F. Toljander Abstract Plant root systems colonized by arbuscular mycorrhizal (AM) fungi have previously been shown to influence soil bacterial populations; however, the direct influence of the AM extraradical mycelium itself on bacterial growth and community composition is not well understood. In this study, we investigated the effects of exudates produced by AM extraradical mycelia on the growth and development of an extracted soil bacterial community in vitro. The chemical composition of the mycelial exudates was analysed using proton nuclear magnetic resonance spectrometry. Following the addition of exudates to a bacterial community extracted from soil, bacterial growth and vitality were determined using a bacterial vitality stain and fluorescence microscopy. Changes in community composition were also analysed at various times over the course of 3 days by terminal restriction fragment length polymorphism analysis, in combination with cloning and sequencing of 16S rRNA genes. Mycelial exudates increased bacterial growth and vitality and changed bacterial community composition. Several Gammaproteobacteria, including a taxon within the Enterobacteriaceae, increased in frequency of occurrence in response to AM mycelial exudates. This study is the first attempt to identify carbohydrates from the extraradical mycelium of an AM fungus, and demonstrates the direct effects of mycelial exudates on a soil bacterial community. [source] Political Violence in the Republic of Rome: Nothing New under the SunGOVERNMENT AND OPPOSITION, Issue 4 2006Brenda J. Lutz At various times the Roman Republic faced outbreaks of domestic political violence, including riots and intimidation, assassinations and conspiracies to overthrow the government. Violence was particularly noticeable in the Early Republic and the Late Republic. These activities were quite similar to the terrorism and violence used by mobs and groups during the French Revolution and the tactics of fascists and leftists in Europe in the 1920s or 1930s. More accurately, the actions of mobs and others during the French Revolution and leftists and fascists in Europe were very similar to the techniques used in the Roman political system in the last five centuries BCE. [source] High frequency of chimerism in transplanted liversHEPATOLOGY, Issue 4 2003Irene Oi-Lin Ng M.D. Recent studies have shown that primitive stem cells can mobilize and differentiate into hepatocytes. We investigated the time and extent in which cells of recipient origins could differentiate into hepatocytes and other cells in human liver allografts. Microsatellite analysis, which can assess quantitatively the proportions of recipient and donor DNA, was performed in posttransplantation liver biopsy specimens from 17 patients at various times. Combined fluorescence in situ hybridization (FISH) for Y chromosome and immunofluorescence for different cell types was also performed in 10 of these cases with sex mismatch. Organ chimerism in the transplanted livers was found to be of variable extent, and the recipients' DNA in the posttransplantation liver biopsy specimens (excluding portal tracts) amounted up to 50%. The recipient DNA in the posttransplantation liver biopsy specimens increased after liver transplantation by as early as 1 week, peaked at around 30 to 40 weeks, and could be shown 63 weeks after transplantation. Most (64%,75%) of the recipientderived cells showed macrophage/Kupffer cell differentiation. Only up to 1.6% of the recipient-derived cells in the liver grafts showed hepatocytic differentiation in the liver grafts and made up 0.62% of all hepatocytes of both donor and recipient origins. These livers had mild or minimal injury histologically. In conclusion, our results show that most of the recipient-derived cells in the liver allografts were macrophages/Kupffer cells and only a small proportion of hepatocytes was recipient derived. However, with regard to recipient-derived hepatocytes, our data cannot distinguish between transdifferentiation and cell fusion. (Hepatology 2003;38:989,998). [source] Sintered Reaction-Bonded Silicon Nitride with High Thermal Conductivity and High StrengthINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2008You Zhou Sintered reaction-bonded silicon nitride (SRBSN) materials were prepared from a high-purity Si powder doped with Y2O3 and MgO as sintering additives by nitriding at 1400°C for 8 h and subsequently postsintering at 1900°C for various times ranging from 3 to 24 h. Microstructures and phase compositions of the nitrided and the sintered compacts were characterized. The SRBSN materials sintered for 3, 6, 12, and 24 h had thermal conductivities of 100, 105, 117, and 133 W/m/K, and four-point bending strengths of 843, 736, 612, and 516 MPa, respectively. Simultaneously attaining thermal conductivity and bending strength at such a high level made the SRBSN materials superior over the high-thermal conductivity silicon nitride ceramics that were prepared by sintering of Si3N4 powder in our previous works. This study indicates that the SRBSN route is a promising way of fabricating silicon nitride materials with both high thermal conductivity and high strength. [source] A new instrumental precipitation dataset for the greater alpine region for the period 1800,2002INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2005Ingeborg Auer Abstract The paper describes the development of a dataset of 192 monthly precipitation series covering the greater alpine region (GAR, 4,18°E by 43,49°N). A few of the time series extend back to 1800. A description is provided of the sometimes laborious processes that were involved in this work: from locating the original sources of the data to homogenizing the records and eliminating as many of the outliers as possible. Locating the records required exhaustive searches of archives currently held in yearbooks and other sources of the states, countries and smaller regional authorities that existed at various times during the last 200 years. Homogeneity of each record was assessed by comparison with neighbouring series, although this becomes difficult when the density of stations reduces in the earliest years. An additional 47 series were used, but the density of the sites in Austria and Switzerland was reduced to maintain an even coverage in space across the whole of the GAR. We are confident of the series back to 1840, but the quality of data before this date must be considered poorer. Of all of the issues involved in homogenizing these data, perhaps the most serious problem is associated with the differences in the height above ground of the precipitation gauges, in particular the general lowering of gauge heights in the late 19th century for all countries, with the exception of Italy. The standard gauge height in the early-to-mid 19th century was 15,30 m above the ground, with gauges being generally sited on rooftops. Adjustments to some series of the order of 30,50% are necessary for compatibility with the near-ground location of gauges during much of the 20th century. Adjustments are sometimes larger in the winter, when catching snowfall presents serious problems. Data from mountain-top observatories have not been included in this compilation (because of the problem of measuring snowfall), so the highest gauge sites are at elevations of 1600,1900 m in high alpine valley locations. Two subsequent papers will analyse the dataset. The first will compare the series with other large-scale precipitation datasets for this region, and the second will describe the major modes of temporal variability of precipitation totals in different seasons and determine coherent regions of spatial variability. Copyright © 2005 Royal Meteorological Society [source] ESR detection of irradiated broad bean (Vicia faba L.) and kinetics of the radiation induced free radical and Mn2+ signalsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2003Mustafa Polat Summary An ESR (Electron Spin Resonance) investigation on irradiated dry broad bean gave a spectrum which was composed of an equally spaced sextet and a single resonance line. These lines appeared at g = 2.0045 (±0.0005) and originated from Mn2+ ions and radiation induced radicals, respectively. Ground broad bean was used throughout the work to avoid any artefacts arising from a microwave cavity filling factor. Free radical signal intensity was observed to increase exponentially in relation to the increase in absorbed dose over the dose range 1.25,15 kGy. Although the Mn2+ signal increases below room temperature, the signal due to the natural and radiation induced radicals decreases. Above room temperature, they both decreased and these decreases were irreversible. The kinetics of these decreases were studied in detail over a temperature range of 308,373 K by annealing samples at different temperatures for various times. [source] Selecting for development of fluoroquinolone resistance in a Campylobacter jejuni strain 81116 in chickens using various enrofloxacin treatment protocolsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010K. Stapleton Abstract Aims:, To determine the effect of various enrofloxacin dose regimes on the colonization and selection of resistance in Campylobacter jejuni strain 81116P in experimentally colonized chickens. Methods and Results:, Two experiments were undertaken, in which 14-day-old chickens were colonized with 1 × 107,1 × 109 CFU g,1Camp. jejuni strain 81116P and then treated with enrofloxacin at 12,500 ppm in drinking water for various times. Caecal colonization levels were determined at various time-points after start-of-treatment, and the susceptibility of recovered isolates to ciprofloxacin was monitored. Resistance was indicated by growth on agar containing 4 ,g ml,1 ciprofloxacin, MICs of 16 ,g ml,1 and the Thr86Ile mutation in gyrA. Enrofloxacin at doses of 12,250 ppm reduced Camp. jejuni colonization over the first 48,72 h after start-of-treatment. The degree of reduction in colonization was dose, but not treatment time, dependent. In all cases, maximal colonization was re-established within 4,6 days. Fluoroquinolone-resistant organisms were recoverable within 48 h of start-of-treatment; after a further 24 h all recovered isolates were resistant. In contrast, a dose of 500 ppm enrofloxacin reduced colonization to undetectable levels within 48 h, and the treated birds remained Campylobacter negative throughout the remaining experimental period. By high pressure liquid chromatography, for all doses, the maximum concentrations of enrofloxacin and ciprofloxacin in the caecal contents were detected at the point of treatment completion. Thereafter, levels declined to undetectable by 7 days post-treatment withdrawal. Conclusions:, In a model using chickens maximally colonized with Camp. jejuni 81116P, treatment with enrofloxacin, at doses of 12,250 ppm in drinking water, enables the selection, and clonal expansion, of fluoroquinolone-resistant organisms. However, this is preventable by treatment with 500 ppm of enrofloxacin. Significance and impact of the study:, Treatment of chickens with enrofloxacin selects for resistance in Camp. jejuni in highly pre-colonized birds. However, a dose of 500 ppm enrofloxacin prevented the selection of resistant campylobacters. [source] Heat resistance of Cronobacter species (Enterobacter sakazakii) in milk and special feeding formulaJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009T.M. Osaili Abstract Aim:, To determine D - and z -values of Cronobacter species (Enterobacter sakazakii) in different reconstituted milk and special feeding formula and the effect of reconstitution of powdered milk and special feeding formula with hot water on the survival of the micro-organism. Methods and Results:, Five Cronobacter species (four C. sakazakii isolates and C. muytjensii) were heated in reconstituted milk or feeding formula pre-equilibrated at 52,58°C for various times or mixed with powdered milk or feeding formula prior to reconstitution with water at 60,100°C. The D -values of Cronobacter at 52,58°C were significantly higher in whole milk (22·10,0·68 min) than in low fat (15·87,0·62 min) or skim milk (15·30,0·51 min) and significantly higher in lactose-free formula (19·57,0·66 min) than in soy protein formula (17·22,0·63 min). The z -values of Cronobacter in reconstituted milk or feeding formula ranged from 4·01°C to 4·39°C. Water heated to ,70°C and added to powdered milk and formula resulted in a > 4 log10 reduction of Cronobacter. Conclusions:, The heat resistance of Cronobacter should not allow the survival of the pathogen during normal pasteurization treatment. The use of hot water (,70°C) during reconstitution appears to be an effective means to reduce the risk of Cronobacter in these products. Significance and Impact of the Study:, This study supports existing data available to regulatory agencies and milk producers that recommended heat treatments are sufficient to substantially reduce risk from Cronobacter which may be present in these products. [source] Glass transition and cold crystallization in carbon dioxide treated poly(ethylene terephthalate)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Yeong-Tarng Shieh Abstract An amorphous poly(ethylene terephthalate) (aPET) and a semicrystalline poly(ethylene terephthalate) obtained through the annealing of aPET at 110°C for 40 min (aPET-110-40) were treated in carbon dioxide (CO2) at 1500 psi and 35°C for 1 h followed by treatment in a vacuum for various times to make samples containing various amount of CO2 residues in these two CO2 -treated samples. Glass transition and cold crystallization as a function of the amount of CO2 residues in these two CO2 -treated samples were investigated by temperature-modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). The CO2 residues were found to not only depress the glass-transition temperature (Tg) but also facilitate cold crystallization in both samples. The depressed Tg in both CO2 -treated poly(ethylene terephthalate) samples was roughly inversely proportional to amount of CO2 residues and was independent of the crystallinity of the poly(ethylene terephthalate) sample. The nonreversing curves of TMDSC data clearly indicated that both samples exhibited a big overshoot peak around the glass transition. This overshoot peak occurred at lower temperatures and was smaller in magnitude for samples containing more CO2 residues. The TMDSC nonreversing curves also indicated that aPET exhibited a clear cold-crystallization exotherm at 120.0°C, but aPET-110-40 exhibited two cold-crystallization exotherms at 109.2 and 127.4°C. The two cold crystallizations in the CO2 -treated aPET-110-40 became one after vacuum treatment. The DMA data exhibited multiple tan , peaks in both CO2 -treated poly(ethylene terephthalate) samples. These multiple tan , peaks, attributed to multiple amorphous phases, tended to shift to higher temperatures for longer vacuum times. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Synthesis and use of pHEMA microbeads with human EA.hy 926 endothelial cellsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Hervé Nyangoga Abstract Cancer has become a major problem in public health and the resulting bone metastases a worsening factor. Facing it, different strategies have been proposed and mechanisms involved in tumor angiogenesis are being studied. Enhanced permeability retention (EPR) effect is a key step in designing new anticancer drugs. We have prepared poly 2-hydroxyethyl methacrylate (pHEMA) microbeads to target human endothelial EA.hy 926 cells, a cell line derived from human umbilical vein endothelial cells. Microbeads were synthesized by emulsion precipitation method and carried positive or negative charges. EA.hy 926 cells were cultured in 24-well plates and microbeads were deposited on cells at various times. Scanning and transmission electron microscopy, flow cytometry, confocal microscopy, and three-dimensional (3D) reconstruction were used to characterize microbeads and their location outside and inside cells. Microbeads were uptaken by endothelial cells with a better internalization for negatively charged microbeads. 3D reconstruction of confocal optical sections clearly evidenced the uptake and internalization of microbeads by endothelial cells. pHEMA microbeads could represent potential drug carrier in tumor model of metastases. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Characteristics of egg and larval production in captive bluespotted gobiesJOURNAL OF FISH BIOLOGY, Issue 5 2001L. A. Privitera Spawning of the Hawaiian coral-reef goby Asterropteryx semipunctata was diurnal, occurring at various times throughout the day. Mean length of eggs deposited in nests was 0·76 mm (range 0·67,0·84); mean egg width was 0·47 mm (range 0·41,0·52). Clutch size varied from 296 to 1552 eggs (mean=886±309), and was independent of standard length, total body weight, and body condition. Mean relative clutch size was 1·59 eggs mg -1 total body weight (range 0·84,2·43). Clutches hatched 4,5 nights after being deposited in a nest. Mean notochord length of newly-hatched larvae was 1·88 mm (range 1·60,2·04). The minimum period of time that elapsed between egg deposition and subsequent growth of a new batch of oocytes to spawning size was 5,6 days, providing a reasonable estimate of minimum spawning interval. Compared with other gobiids, tropical species tend to have shorter incubation periods, smaller eggs and smaller larvae at hatching. [source] Ultrasonic Investigation of the Effect of Vegetable Shortening and Mixing Time on the Mechanical Properties of Bread DoughJOURNAL OF FOOD SCIENCE, Issue 9 2009K.L. Mehta ABSTRACT:, Mixing is a critical stage in breadmaking since it controls gluten development and nucleation of gas bubbles in the dough. Bubbles affect the rheology of the dough and largely govern the quality of the final product. This study used ultrasound (at a frequency where it is sensitive to the presence of bubbles) to nondestructively examine dough properties as a function of mixing time in doughs prepared from strong red spring wheat flour with various amounts of shortening (0%, 2%, 4%, 8% flour weight basis). The doughs were mixed for various times at atmospheric pressure or under vacuum (to minimize bubble nucleation). Ultrasonic velocity and attenuation (nominally at 50 kHz) were measured in the dough, and dough density was measured independently from specific gravity determinations. Ultrasonic velocity decreased substantially as mixing time increased (and more bubbles were entrained) for all doughs mixed in air; for example, in doughs made without shortening, velocity decreased from 165 to 105 ms,1, although superimposed on this overall decrease was a peak in velocity at optimum mixing time. Changes in attenuation coefficient due to the addition of shortening were evident in both air-mixed and vacuum-mixed doughs, suggesting that ultrasound was sensitive to changes in the properties of the dough matrix during dough development and to plasticization of the gluten polymers by the shortening. Due to its ability to probe the effect of mixing times and ingredients on dough properties, ultrasound has the potential to be deployed as an online quality control tool in the baking industry. [source] Soluble Albumin and Biological Value of Protein in Cocoa (Theobroma cacao L.) Beans as a Function of Roasting TimeJOURNAL OF FOOD SCIENCE, Issue 4 2005Luis Abecia-Soria ABSTRACT: An association has been identified between the extent of roasting and the amount of extractable protein from the cocoa bean, its nutritive value, and the sensorial quality of the liquor. Cocoa nibs from fermented seeds (Theobroma cacao L.) were precision-roasted at 150°C for 0, 30, 34, 38, 42, and 46 min and the protein fraction extracted. From the beginning of roasting, until minute 38, about 87% of the proteins were extractable, but the extractability substantially decreased to 72.7% at 42 min and to 65.3% at 46 min. Both total soluble protein determination and albumin concentration of the roasted nibs diminished slightly until minute 38, when acceptable sensory characteristics were obtained for the liquor. Both total nitrogen and capillary-electrophoretic separation and quantification of the albumin showed that the amounts of extractable protein in this fraction consistently followed a cyclic pattern until minute 42, irreversibly decreasing thereafter. Biological evaluation of the protein from the cocoa nibs roasted for the various times showed that at the point that the sensory rating approached that of a commercial liquor, the albumin content and nutritive value were still high. The findings suggest that with moderate, uniform roasting it may not be necessary to sacrifice the protein's biological value for the sensorial attributes of chocolate in a standard commercial roast. [source] Cytokine profile of liver-infiltrating CD4+ T cells separated from murine primary biliary cirrhosis-like hepatic lesions induced by graft-versus-host reactionJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 4 2000Shinichi Itoh Abstract Background and Methods: We have previously reported that CD4+ T cells induced primary biliary cirrhosis (PBC)-like hepatic lesions in mice with graft-versus-host reaction due to major histocompatibility complex class II disparity. To clarify the relationship between the cytokine profile produced by CD4+ T cells and the formation of hepatic lesions, we sorted CD4+ T cells from the liver by using flow cytometry and examined their cytokine mRNA expression at various times after GVHR induction. We also examined the associated changes in the serum levels of antimitochondrial antibodies (AMA). Results: Histologically, the infiltration of CD4+ T cells around the bile ducts was observed from day 5, and the lesions deteriorated gradually until day 14. On day 14, CD8+, B220+ and Mac-1+ cells, as well as CD4+ T cells were seen around the bile ducts. In the liver-infiltrating CD4+ T cells, the expression level of interferon-, (IFN-,) mRNA was observed to increase at an early phase (day 3), whereas that of interleukin (IL)-10 mRNA was elevated at a later phase (day 14). The elevation of IFN-, mRNA expression at an early phase before the appearance of non-suppurative destructive cholangitis suggests that IFN-, may be related to the pathogenesis of PBC in this model. Serum levels of AMA on day 14 were significantly higher than those on day 5. Interleukin-10 was considered to stimulate antibody production, to show an inhibitory effect upon the function of T helper 1 cells, and to inhibit fibrosis. Conclusions: Interferon-, may play an important role in the pathogenesis of this model. Moreover, delayed expression of IL-10 mRNA may control PBC-like hepatic lesions. [source] The Federal Home Loan Bank System: The Lender of Next-to-Last Resort?JOURNAL OF MONEY, CREDIT AND BANKING, Issue 4 2010ADAM ASHCRAFT government-sponsored enterprise; lender of last resort; liquidity The Federal Home Loan Bank (FHLB) System is a large cooperatively owned government-sponsored liquidity facility that lends predominately to U.S. depository institutions. This paper documents the significant role played by the FHLB System at the outset of the recent financial crisis and provides evidence on the uses of FHLB funding by member banks and thrifts during that time. We then compare lending activity by the FHLB System and the Federal Reserve during 2007 and 2008, discuss the types of institutions seeking government-sponsored liquidity at various times, and identify the trade-offs faced by borrowers eligible to tap liquidity from both facilities. [source] Enhanced hippocampal F2 -isoprostane formation following kainate-induced seizuresJOURNAL OF NEUROCHEMISTRY, Issue 5 2001Manisha Patel We attempted to obtain evidence for the occurrence of oxidant injury following seizure activity by measuring hippocampal F2 -isoprostanes (F2 -IsoPs), a reliable marker of free radical-induced lipid peroxidation. Formation of F2- IsoPs esterified in hippocampal phospholipids was correlated with hippocampal neuronal loss and mitochondrial aconitase inactivation, a marker of superoxide production in the kainate model. F2 -IsoPs were measured in microdissected hippocampal CA1, CA3 and dentate gyrus (DG) regions at various times following kainate administration. Kainate produced a large increase in F2 -IsoP levels in the highly vulnerable CA3 region 16 h post injection. The CA1 region showed small, but statistically insignificant increases in F2 -IsoP levels. Interestingly, the DG, a region resistant to kainate-induced neuronal death also showed marked (2.5,5-fold) increases in F2 -IsoP levels 8, 16, and 24 h post injection. The increases in F2 -Isop levels in CA3 and DG were accompanied by inactivation of mitochondrial aconitase in these regions. This marked subregion-specific increase in F2 -Isop following kainate administration suggests that oxidative lipid damage results from seizure activity and may play an important role in seizure-induced death of vulnerable neurons. [source] Identification and Regulation of Genes from a Biocontrol Strain of Fusarium oxysporumJOURNAL OF PHYTOPATHOLOGY, Issue 9 2007D. R. Fravel Abstract Differential display with three time points revealed that thiram altered expression of numerous genes in the biocontrol fungus Fusarium oxysporum CS-20. Of the 101 bands purified from the differential display gel, 86 were successfully cloned, and 64 sequenced. Based on nucleic acid sequences, homology to known products was found using BLASTn for 26 sequences and homology to hypothetical proteins was found for six sequences, also from Gibberella zeae. One band (BM1 24-1) showed homology to an ABC transporter from three different fungi. Because of its association with detoxification functions, the ABC transporter was selected for further study. Mycelia of CS-20 were exposed to 25 ,g active ingredient (a.i.) thiram in liquid culture for various times from 0 to 8 h. Quantitative real-time PCR was used to evaluate gene expression. At 30 min after treatment with thiram, the ABC transporter was upregulated 20- to 25-fold relative to the control treatment. The ABC transporter was upregulated 15-fold at 1 h after treatment and 10-fold at 2 h. At 8 h after treatment, there was no difference between treated and non-treated for expression of the ABC transporter. Transcription of the gene encoding EST BM1 24-1 is induced in response to thiram treatment and may function in providing resistance in F. oxysporum isolate CS-20 to fungicides and other toxins. Tolerance to toxins may be critical to the successful inclusion of CS-20 in disease control strategies in cropping systems. [source] Aryl acrylate based high-internal-phase emulsions as precursors for reactive monolithic polymer supportsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2005Peter Krajnc Abstract Water-in-oil high-internal-phase emulsions (HIPEs), containing 4-nitrophenyl acrylate and 2,4,6-trichlorophenyl acrylate as reactive monomers, were prepared and polymerized, and highly porous monolithic materials resulted. The novel materials were studied by combustion analysis, Fourier transform infrared spectroscopy scanning electron microscopy, mercury porosimetry, and N2 adsorption/desorption analysis. With both esters, cellular macroporous monolithic polymers were obtained; the use of 4-nitrophenyl acrylate resulted in a cellular material with void diameters between 3 and 7 ,m and approximately 3-,m interconnects, whereas the use of 2,4,6-trichlorophenyl acrylate yielded a foam with void diameters between 2 and 5 ,m, most interconnects being around 1 ,m. The resulting monoliths proved to be very reactive toward nucleophiles, and possibilities of functionalizing the novel polymer supports were demonstrated via reactions with amines bearing additional functional groups and via the synthesis of an acid chloride derivative. Tris(hydroxymethyl)aminomethane and tris(2-aminoethyl)amine derivatives were obtained. The hydrolysis of 4-nitrophenylacrylate removed the nitrophenyl group, yielding a monolithic acrylic acid polymer. Furthermore, functionalization to immobilized acid chloride was performed very efficiently, with more than 95% of the acid groups reacting. The measurement of the nitrogen content in 4-nitrophenyl acrylate poly(HIPE)s after various times of hydrolysis showed the influence of the total pore volume of the monolithic polymers on the velocity of the reaction, which was faster with the more porous polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 296,303, 2005 [source] The black,white "achievement gap" as a perennial challenge of urban science education: A sociocultural and historical overview with implications for research and practice,JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 10 2001Obed Norman A perennial challenge for urban education in the United States is finding effective ways to address the academic achievement gap between African American and White students. There is widespread and justified concern about the persistence of this achievement gap. In fact, historical evidence suggests that this achievement gap has existed at various times for groups other than African Americans. What conditions prevailed when this achievement gap existed for these other groups? Conversely, under what conditions did the gap diminish and eventually disappear for these groups? This article explores how sociocultural factors involved in the manifestation and eventual disappearance of the gap for these groups may shed some light on how to address the achievement gap for African American students in urban science classrooms. Our conclusion is that the sociocultural position of groups is crucial to understanding and interpreting the scholastic performance of students from various backgrounds. We argue for a research framework and the exploration of research questions incorporating insights from Ogbu's cultural, ecological theory, as well as goal theory, and identity theory. We present these as theories that essentially focus on student responses to societal disparities. Our ultimate goal is to define the problem more clearly and contribute to the development of research-based classroom practices that will be effective in reducing and eventually eliminating the achievement gap. We identify the many gaps in society and the schools that need to be addressed in order to find effective solutions to the problem of the achievement gap. Finally, we propose that by understanding the genesis of the gap and developing strategies to harness the students' responses to societal disparities, learning can be maximized and the achievement gap can be significantly reduced, if not eliminated entirely, in urban science classrooms. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 1101,1114, 2001 [source] | ||||||||||||||||||||||||||||||||||