			Home About us Contact

Main Parameters (main + parameter)

Distribution by Scientific Domains

Medical Sciences	21%
Life Sciences	21%
Chemistry	15%
Engineering	12%
Polymers and Materials Science	9%
Physics and Astronomy	9%
Earth and Environmental Science	6%

Selected Abstracts

Plasma anhydro- d -glucitol (1,5-AG) as an indicator of hyperglycaemic excursions in pregnant women with diabetes

DIABETIC MEDICINE, Issue 2 2006
M. Dworacka
Abstract Aims To evaluate the use of the plasma 1,5-anhydro- d -glucitol (1,5-AG) level as a possible marker for glucose excursions in pregnant women with diabetes. Methods The study group consisted of 55 pregnant women with diabetes (gestational diabetes mellitus,GDM, n = 28 or pre-gestational diabetes mellitus ,PGDM, n = 27), without hepatic or renal insufficiency, gestational age range 5,38 weeks. In each patient, 24-h glucose profile, glycated haemoglobin and 1,5-AG plasma levels were measured. Mean blood glucose (MBG) and M-value (by Schlichtkrull) were calculated. MBG, M-value and maximal daily glycaemia (MxG) were used as indexes of daily glycaemic excursions. Results A significant correlation was found between the 1,5-AG plasma level and MxG [r = (,0.3)] and between the 1,5-AG level and M-value [r = (,0.36)]. There was no association between the 1,5-AG level and gestational age. Multivariate regression analysis, with 24-h glucose profile, gestational age and MxG as independent variables, showed that MxG was the main parameter determining the 1,5-AG plasma level [, = (,0.68)]. The M-value, the coefficient of glucose fluctuations, also determined the 1,5-AG level but with lower statistical power [, = (0.41)]. No statistical differences were found in the group with HbA1c < 6% or > 6% for 1,5-AG and M-value, while MBG was higher in poorly controlled patients (HbA1c > 6%). Conclusions The plasma 1,5-AG level may be a useful marker of daily glucose excursion in pregnant women with diabetes, as an adjunct to HbA1c monitoring. [source]

Prevalence of Head Trauma in Patients With Difficult Headache: The North Norway Headache Study

HEADACHE, Issue 1 2003
Svein Ivar Bekkelund MD
Objective.,To test whether chronic headache (>3 days/week) is more prevalent than episodic headache (<3 days/week) in patients with a previous history of significant head trauma. Method.,We included 903 consecutive patients referred to a specialist center for headache during a period of 2 years. As the main parameter, we selected self-reported history of previous significant head trauma defined as loss of consciousness or hospitalization due to head trauma. Results.,One hundred eighty-nine out of 903 patients with difficult headache referred to a neurologist had a previous history of head trauma (21%). We identified 297 patients with headache 3 days or more per week (33%). Of these patients with chronic headache, 68 (23%) reported previous significant head trauma compared with 121/714 (17%) in other patients with headache (P = .18). Shorter length of education was associated with chronic headache; however, age, sex, or specific headache syndromes such as migraine or tension headache were not related to chronicity. Conclusion.,Although the incidence of previous head trauma was prevalent in this highly selected group of patients with headache, such a history was not a predictor of chronicity. [source]

Total eclipse silences grasshoppers' and bushcrickets' songs

JOURNAL OF ZOOLOGY, Issue 4 2001
Franz Peter Fischer
Abstract A total eclipse of the sun is a very rare event for a given geographical location, and it is not easy to predict the reaction of animals to such events. On 11 August 1999, the reaction of some species of Saltatoria was quantitatively analysed in a long-term study area for which the normal diurnal song patterns are well established. The song activity of the grasshoppers and bushcrickets declined slowly during the partial eclipse, and stopped completely during the 2-min total eclipse. After a marked delay, song activity returned suddenly to normal. This suggests that light intensity is the main parameter controlling the diurnal song pattern in the species studied, and obviously overrides any internal rhythm. [source]

Preparation of oily core polyamide microcapsules via interfacial polycondensation,

POLYMER INTERNATIONAL, Issue 4 2003
L Soto-Portas
Abstract Microcapsules obtained by interfacial polycondensation from an original system based on the polyaddition of specific di- or polyamines and more classical acyl chloride molecules were studied. The originality of the system lies in the fact that the encapsulated agent is the internal phase allowing its incorporation without an organic solvent, which is an advantage from the point of view of environmental protection. Once the optimal parameters of the emulsion were determined, the membrane formation was studied by optimizing the emulsification and reaction times in relation to simultaneous acyl chloride hydrolysis. The microcapsules were obtained by interfacial polycondensation between an excess of amine functions (diamine and diethylenetriamine) and acyl chloride (sebacoyl chloride and 1,3,5-benzene tricarbonyl trichloride) from an oil-in-water emulsion in the presence of 88% hydrolyzed poly(vinyl alcohol) as a surfactant. Various formulations in terms of COCl concentration, crosslinking agent concentration, excess of amine functions, emulsification and reaction times were prepared. The hydrolysis of acyl halide functions is the main parameter which influences the growth of the membrane. The increase in acyl chloride function concentration allows compensation for that lost by hydrolysis, and increases the encapsulation yield to about 90%. The degree of crosslinking of the membrane was controlled in order to minimize the subsequent release of oil by the addition of trifunctional monomers. An optimal formulation was developed offering high encapsulation yield and optimal elastic behaviour. Almost spherical capsules, with a membrane thickness of approximately 500,nm, relatively smooth internal walls and crumpled external walls, were observed by scanning electron microscopy. © 2003 Society of Chemical Industry [source]

The nature of collision-induced dissociation processes of doubly protonated peptides: comparative study for the future use of matrix-assisted laser desorption/ionization on a hybrid quadrupole time-of-flight mass spectrometer in proteomics

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2001
R. Cramer
Comparative MS/MS studies of singly and doubly charged electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) precursor peptide ions are described. The spectra from these experiments have been evaluated with particular emphasis on the data quality for subsequent data processing and protein/amino acid sequence identification. It is shown that, once peptide ions are formed by ESI or MALDI, their charge state, as well as the collision energy, is the main parameter determining the quality of collision-induced dissociation (CID) MS/MS fragmentation spectra of a given peptide. CID-MS/MS spectra of singly charged peptides obtained on a hybrid quadrupole orthogonal time-of-flight mass spectrometer resemble very closely spectra obtained by matrix-assisted laser desorption/ionization post-source decay time-of-flight mass spectrometry (MALDI-PSD-TOFMS). On the other hand, comparison of CID-MS/MS spectra of either singly or doubly charged ion species shows no dependence on whether ions have been formed by ESI or MALDI. This observation confirms that, at the time of precursor ion selection, further mass analysis is effectively decoupled from the desorption/ionization event. Since MALDI ions are predominantly formed as singly charged species and ESI ions as doubly charged, the associated difference in the spectral quality of MS/MS spectra as described here imposes direct consequences on data processing, database searching using ion fragmentation data, and de novo sequencing when ionization techniques are changed. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A Quantitative Conservation Approach for the Endangered Butterfly Maculinea alcon

CONSERVATION BIOLOGY, Issue 2 2004
MICHIEL F. WallisDeVries
The quality and size of habitat patches and their isolation from other patches are the main parameters for an assessment of population persistence, but translating persistence probabilities into practical measures is still a weak link in conservation management. I provide a quantitative conservation approach for the endangered myrmecophilous butterfly Maculinea alcon in the Netherlands. All 127 colonies known on heathland since 1990 were investigated for patch quality, size, and isolation. I assessed habitat quality in three 10 × 10 m plots for most colonies. Site occupancy in 1998,1999 was only 56%. Occupancy was best explained by a logistic regression including patch area, host ant presence, host plant abundance, overall heathland area, and connectivity between sites ( R2= 0.410, p < 0.0001); it correctly classified the occupied or vacant status for 82% of the sites. Connectivity contributed only 3.6% to the total explained variation of site occupancy, indicating that habitat characteristics were more important than isolation in determining population persistence at the examined scale level (>500 m). Grazing and sod cutting had a beneficial impact, but in combination these practices proved detrimental. Hydrological measures to prevent drainage were also associated with lowered occupancy. I used the different components in the logistic regression to formulate objective management recommendations. These consisted of sod cutting, reduction of management intensity, enlargement of habitat, or combinations of these recommendations. The results highlight the importance of careful management when site quality is determined by multiple factors. The quantitative conservation approach followed here can be fruitfully extended to other endangered species, provided enough is known about their ecological requirements and how management actions affect them. Resumen:,La preservación de fragmentos individuales es extremadamente importante para especies en peligro con capacidad de dispersión limitada. La calidad y tamaño de los fragmentos de hábitat y su aislamiento de otros fragmentos son los parámetros principales para la evaluación de la persistencia de la población, pero la traducción de probabilidades de persistencia en medidas prácticas aun es un eslabón débil en la gestión de conservación. Proporciono un método cuantitativo de conservación para la mariposa mirmecófila Maculinea alcon en peligro en Holanda. Se investigó a las 127 colonias conocidas en brezales desde 1990 para calidad, tamaño y aislamiento del fragmento. Evalué la calidad del hábitat en tres parcelas de 10 × 10 m en la mayoría de las colonias. La ocupación de sitios en 1998-1999 fue sólo 56%. La ocupación fue mejor explicada por regresión logística incluyendo la superficie del fragmento, presencia de hormigas huésped, abundancia de plantas huésped, superficie total del brezal y conectividad entre sitios ( R2= 0.410, p < 0.0001); clasificó el estatus de ocupado o vacante en 82% de los sitios. La conectividad contribuyó con solo 36% de la variación total de sitio de ocupación, lo que indica que las características de hábitat fueron más importantes que el aislamiento en la determinación de la persistencia de la población en el nivel de escala examinado (>500 m). El pastoreo y el corte de pasto tuvieron un impacto benéfico pero combinadas, estas prácticas fueron perjudiciales. Obras hidrológicas para prevenir la desecación también se asociaron con una disminución en la ocupación. Utilicé los diferentes componentes de la regresión logística para formular recomendaciones objetivas de gestión. Estas incluyeron el corte de pasto, reducción en la intensidad de manejo, aumento de hábitat o combinaciones de estas recomendaciones. Los resultados resaltan la importancia de la gestión cuidadosa cuando la calidad del sitio está determinada por múltiples factores. El método cuantitativo de preservación utilizado puede ser extendido exitosamente a otras especies en peligro, siempre que sean suficientemente conocidos sus requerimientos ecológicos y la forma en que le afectan las acciones de manejo. [source]

Simulated microgravity activates MAPK pathways in fibroblasts cultured on microgrooved surface topography

CYTOSKELETON, Issue 2 2008
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 ,m, width: 1 ,m), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment. Expression of collagen type I, and ,1-, ,1-, ,3-integrin were investigated by QPCR. Finally, immunoblotting was applied to visualise MAPK signalling pathways. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces under simulated microgravity, after 48 h of culturing appeared similar to those cultured at 1g, although cell shape was different. Analysis of variance proved that all main parameters: topography, gravity force, and time were significant. In addition, gene levels were reduced by simulated microgravity particularly those of ,3-integrin and collagen, however alpha-1 and beta-1 integrin levels were up-regulated. ERK1/2 was reduced in RPM, however, JNK/SAPK and p38 remained active. The members of the small GTPases family were stimulated under microgravity, particularly RhoA and Cdc42. The results are in agreement that application of microgravity to fibroblasts promotes a change in their morphological appearance and their expression of cell-substratum proteins through the MAPK intracellular signalling pathways. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

The effect of combined simulated microgravity and microgrooved surface topography on fibroblasts

CYTOSKELETON, Issue 3 2007
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 ,m, width: 1, 2, 5, and 10 ,m), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment and area. Confocal laser scanning microscopy visualised distribution of actin filaments and focal adhesion points. Finally, expression of collagen type I, fibronectin, and ,1- and ,1-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces decreased under simulated microgravity, especially after 24 h of culturing. Cell surface area on grooved substrata were significantly smaller than on smooth substrata, but simulated microgravity on the grooved groups resulted in an enlargement of cell area. ANOVA was performed on all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, gene levels were reduced by microgravity particularly those of ,1-integrin and fibronectin. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by microgravity conditions. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

The effect of combined hypergravity and microgrooved surface topography on the behaviour of fibroblasts

CYTOSKELETON, Issue 7 2006
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 1 ,m, width: 1, 2, 5, 10 ,m), which undergo artificial hypergravity by centrifugation (10, 24 and 50 g; or 1 g control). The aim of the study was to clarify which of these parameters was more important to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell spreading and alignment. Confocal laser scanning microscopy visualised distribution of actin filaments and vinculin anchoring points through immunostaining. Finally, expression of collagen type I, fibronectin, and ,1 - and ,1 -integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata (control), cells spread out in a random fashion. The alignment of cells cultured on grooved surfaces increased with higher g-forces until a peak value at 25 g. An ANOVA was performed on the data, for all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, most gene levels were reduced by hypergravity. Still, collagen type 1 and fibronectin are seemingly unaffected by time or force. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by hypergravity forces. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source]

Seismic performance evaluation of steel arch bridges against major earthquakes.

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2004
Part 1: dynamic analysis approach
Abstract In this study the inelastic behavior of steel arch bridges subjected to strong ground motions from major earthquakes is investigated by dynamic analyses of a typical steel arch bridge using a three-dimensional (3D) analytical model, since checking seismic performance against severe earthquakes is not usually performed when designing such kinds of bridge. The bridge considered is an upper-deck steel arch bridge having a reinforced concrete (RC) deck, steel I-section girders and steel arch ribs. The input ground motions are accelerograms which are modified ground motions based on the records from the 1995 Hyogoken-Nanbu earthquake. Both the longitudinal and transverse dynamic characteristics of the bridge are studied by investigation of time-history responses of the main parameters. It is found that seismic responses are small when subjected to the longitudinal excitation, but significantly large under the transverse ground motion due to plasticization formed in some segments such as arch rib ends and side pier bases where axial force levels are very high. Finally, a seismic performance evaluation method based on the response strain index is proposed for such steel bridge structures. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Adhesion and Percolation Parameters in Two Dimensional Pd,LSCM Composites for SOFC Anode Current Collection

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010
Samir Boulfrad
Abstract This paper is concerned with palladium,(La0.75Sr0.25)0.97Cr0.5Mn0.5O3 (LSCM) composite current collectors for solid oxide fuel cells (SOFCs); the composites, which are in a 2D configuration (thickness of about 8,10,µm), are deposited upon an LSCM electrode layer on top of an yttria zirconia electrolyte substrate. The influence of the LSCM particle size on the adhesion between palladium and LSCM are reported and discussed. Compositions using four different LSCM particle sizes (0.21, 0.49, 0.64, and 0.81,µm) with sintered Pd particle sizes approaching 10,µm are investigated. The best bonding is obtained when smaller particles are used. The electrical dc conductivity of the composite is reported as a function of the palladium volume fraction for all used LSCM particle sizes. The measured experimental values present typical insulating,conductive percolation. However, the transition occurs at ,33% of the conductive phase, that is, a lower percentage than for 2D ideal systems and a higher percentage than for 3D ideal systems. This is consistent with lower-dimension percolation for a system of large-grained conductors and small-grained insulators. The general effective media (GEM) equation is used to fit the experimental data, and the two main parameters (the threshold point ,c and the exponent t) are defined. [source]

Which parameters differ in very old patients with chronic atrial fibrillation treated by anticoagulant or aspirin?

FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 5 2008
Antithrombotic treatment of atrial fibrillation in the elderly
Abstract The objective was to determine the main parameters taken into account for the decision of antithrombotic treatment of atrial fibrillation (AF) by vitamin K antagonist or aspirin. This was a prospective clinical study of four clinical services of geriatric medicine. Two hundred and nine inpatients, 84.7 ± 7 years (women 60.8%), with chronic AF were included. The patients were distributed into two groups (anticoagulant or aspirin) according to medical decision. All the decision criteria for treatment were recorded: cardiopathy, conditions of life, clinical examination (nutrition and autonomy, mini-mental state examination (MMSE), walking evaluation, comorbidity), subjective evaluation of risk of falls and glomerular filtration rate. The thromboembolic risk and the bleeding risk, evaluated subjectively for each patient, were compared with two scores of thrombo-embolic risk and bleeding risk. The evolution of the patients was recorded after 3 months. Student's t -test and chi-squared tests were used for statistical analysis. One hundred and two patients (48.8%) received anticoagulant and 107 patients received aspirin. Patients in the aspirin group were significantly older (86.5 ± 6.5 vs. 82.9 ± 7.1 years), with more frequent social isolation, higher systolic blood pressure, and had more important subjective bleeding risk and risk of falls. Patients in the anticoagulant group had significantly more valvulopathies and a more important subjective thromboembolic risk. Thrombo-phlebitis antecedents, dementia, denutrition and walking alterations were only slightly more frequent in patients in the aspirin group. Physicians underestimated thromboembolic risk (one-third of patients) and they overestimated bleeding risk (half of the patients). After 3 months, the two groups did not significantly differ for death, bleeding or ischaemic events. In common practice, the decision of antithrombotic treatment for AF should take into account not only cardiovascular but also geriatric criteria. [source]

The tectonic regime along the Andes: Present-day and Mesozoic regimes

GEOLOGICAL JOURNAL, Issue 1 2010
Victor A. Ramos
Abstract The analyses of the main parameters controlling the present Chile-type and Marianas-type tectonic settings developed along the eastern Pacific region show four different tectonic regimes: (1) a nearly neutral regime in the Oregon subduction zone; (2) major extensional regimes as the Nicaragua subduction zone developed in continental crust; (3) a Marianas setting in the Sandwich subduction zone with ocean floored back-arc basin with a unique west-dipping subduction zone and (4) the classic and dominant Chile-type under compression. The magmatic, structural and sedimentary behaviours of these four settings are discussed to understand the past tectonic regimes in the Mesozoic Andes based on their present geological and tectonic characteristics. The evaluation of the different parameters that governed the past and present tectonic regimes indicates that absolute motion of the upper plate relative to the hotspot frame and the consequent trench roll-back velocity are the first order parameters that control the deformation. Locally, the influences of the trench fill, linked to the dominant climate in the forearc, and the age of the subducted oceanic crust, have secondary roles. Ridge collisions of seismic and seismic oceanic ridges as well as fracture zone collisions have also a local outcome, and may produce an increase in coupling that reinforces compressional deformation. Local strain variations in the past and present Andes are not related with changes in the relative convergence rate, which is less important than the absolute motion relative to the Pacific hotspot frame, or changes in the thermal state of the upper plate. Changes in the slab dip, mainly those linked to steepening subduction zones, produce significant variations in the thermal state, that are important to generate extreme deformation in the foreland. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Association of hyperhomocysteinemia and folate deficiency with colon tumors in patients with inflammatory bowel disease

INFLAMMATORY BOWEL DISEASES, Issue 2 2008
Jean Marc Phelip
Abstract Background: Folate deficiency associated with hyperhomocysteinemia might increase the risk of developing colorectal cancer. The aim of this study was to evaluate factors associated with colonic carcinogenesis, in particular, folate and homocysteinemia levels, in a cross-sectional study of patients with inflammatory bowel disease (IBD). Methods: IBD patients with carcinogenic lesions discovered during colonoscopy [dysplasia-associated lesion or masses (DALM), colorectal cancer] were included and compared with the whole population of IBD patients with a normal colonoscopy performed during the same period. The following parameters were collected at the time of colonoscopy: age, sex, type, duration, activity, and extent of the disease, treatment, smoking status, and vitamin B12, folate, and homocysteinemia levels. Univariate and multivariate analyses were performed after adjusting for the main parameters. Results: One hundred and fourteen patients [41 with ulcerative colitis (UC), 73 with Crohn's disease (CD)] were included. Twenty-six carcinogenic lesions were isolated: 18 DALM (7 high-grade and 11 low-grade dysplasia) and 8 colorectal cancers. In univariate analysis, the factors associated with carcinogenesis were: active smoking (P = 0.03), folate level < 145 pmol/L (P = 0.02), hyperhomocysteinemia > 15 ,mol/L (P = 0.003), duration of disease > 10 years (P = 0.006), and UC (P = 0.02). In multivariate analysis, patients with hyperhomocysteinemia associated with folate deficiency had 17 times as many carcinogenic lesions as patients with normal homocysteinemia whatever the folate status and duration of the disease (P = 0.01). Patients with hyperhomocysteinemia without folate deficiency had 2.5 times as many carcinogenic lesions as patients with normal homocysteinemia (P = 0.08). Conclusions: Our data suggest that in IBD patients with normal homocysteinemia, the increase in carcinogenic risk is negligible. Conversely, in patients with hyperhomocysteinemia, folate deficiency may be associated with increased colorectal carcinogenesis in IBD patients. (Inflamm Bowel Dis 2007) [source]

Analysis of energy technology changes and associated costs

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2006
P. D. Lund
Abstract An integrated mathematical model constituting of interlinked submodels on technology costs, progress and market penetration has been developed. The model was applied to a few new energy technologies to investigate the economic boundary conditions for a full market breakthrough and corresponding market impact on a 50 years time scale. The model shows that public subsidies amounting to slightly over 220 billion , in total worldwide would be necessary over the next 30,40 years to bring wind and photovoltaics to a cost breakthrough in the market and to reach a 20 and 5% share of all electricity at t = 50 years, respectively. These up-front learning investments would be partly amortized toward the end of the interval as the new technologies become cost competitive but could be fully paid off earlier if CO2 emission trading schemes emerge even with modest CO2 price levels. The findings are sensitive to changes in the parameter assumptions used. For example, a 2% uncertainty in the main parameters of the model could lead to a spread of tens of per cents in the future energy impact and subsidy needs, or when related to the above subsidy estimate, 155,325 billion ,. This underlines the overall uncertainty in predicting future impacts and resource needs for new energy technologies. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Effect of gamma-ray irradiation on the physicochemical properties of flour and starch granule structure for wheat

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2009
Jun Wang
Summary Effect of gamma irradiation on the physicochemical properties of flour and starch granule structure of wheat was compared to non-irradiated wheat. The moisture content of wet gluten and titratable acidity of wheat flour were significantly affected by gamma irradiation. This treatment also destroyed the starch granules of wheat grain and their breakage augmented as the dose of gamma irradiation increased, apparently resulting in the increase of small starch granules. Probably, these results were due to the disruption of large molecule, such as proteins, lipids and starch. The irradiated wheat flour for RVA pasting properties (flour viscosity) was also evaluated. Besides the difference in RVA profile, starch pasting curves showed a considerable decrease for six main parameters as gamma irradiation dose at different velocity increased. [source]

Simulation analyses of weighted fair bandwidth-on-demand (WFBoD) process for broadband multimedia geostationary satellite systems

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2005
Güray Açar
Abstract Advanced resource management schemes are required for broadband multimedia satellite networks to provide efficient and fair resource allocation while delivering guaranteed quality of service (QoS) to a potentially very large number of users. Such resource management schemes must provide well-defined service segregation to the different traffic flows of the satellite network, and they must be integrated with some connection admission control (CAC) process at least for the flows requiring QoS guarantees. Weighted fair bandwidth-on-demand (WFBoD) is a resource management process for broadband multimedia geostationary (GEO) satellite systems that provides fair and efficient resource allocation coupled with a well-defined MAC-level QoS framework (compatible with ATM and IP QoS frameworks) and a multi-level service segregation to a large number of users with diverse characteristics. WFBoD is also integrated with the CAC process. In this paper, we analyse via extensive simulations the WFBoD process in a bent-pipe satellite network. Our results show that WFBoD can be used to provide guaranteed QoS for both non-real-time and real-time variable bit rate (VBR) flows. Our results also show how to choose the main parameters of the WFBoD process depending on the system parameters and on the traffic characteristics of the flows. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Stones in anomalous kidneys: Results of treatment by shock wave lithotripsy in 150 patients

INTERNATIONAL JOURNAL OF UROLOGY, Issue 10 2004
LUTFI TUNC
Abstract Objective:, To determine the efficacy of shock wave lithotripsy (SWL) in anomalous kidneys. Methods:, From October 1990 to October 2002, 150 patients (93 men and 57 women) with anomalous urinary tracts, including 45 horseshoe kidneys, 57 duplex kidneys, 30 malrotated kidneys, 14 pelvic and four crossed ectopic kidneys were treated with SWL for urolithiasis at the Gazi University Faculty of Medicine. Shock wave lithotripsy was performed with Siemens Lithostar plus (Siemans, Erlanger, Germany) device and all procedures were carried under fluoroscopic control. Results:, The mean shock wave number and intensity received by the patients was 3770 (range, 1380,4100) shocks and 18.4 (range, 16.1,19) kV per session, respectively. The minimum success rate was obtained in patients with lower calyceal (50%) followed by middle calyceal (60%) calculi. The stone-free rate decreased and the number of sessions per patient increased with increasing stone diameter (dm). In patients with a stone dm > 30 mm, only 34% could be stone-free, compared to a rate of 92% for calculi dm < 10 mm. The overall stone free rate at the third month was 68%. The best stone-free rates were obtained in patients with ureteral duplication (80.7%). The stone-free rates in horseshoe, malrotated, pelvic and crossed ectopic kidneys were found to be 66.7%, 56.7%, 57.2% and 25%, respectively. Conclusion:, Shock wave lithotripsy might be an effective and minimally invasive treatment alternative in stone-bearing anomalous kidneys. The type of anomaly, stone burden and localization seem to be the main parameters effecting the treatment success. [source]

Study of the production of hydrogen bubbles at low current densities for electroflotation processes

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2010
Carlos Jiménez
Abstract BACKGROUND: Flotation processes are widely used in waste-water treatment and it is quite important to have a tool to determine and optimize the size distribution of the bubbles produced. In this work, the electrochemical production of bubbles to enhance the performance of electrocoagulation processes by flotation is studied. To do this, a current density range characteristic of electrocoagulation processes is used to produce microbubbles (<5 mA cm,2), instead of the higher values used in other studies to characterize electroflotation in non-combined processes. RESULTS: Current density and pH were found to influence the process significantly. In the range used, higher current densities allow a larger number of small size bubbles to be obtained, appropriate for use in electroflotation processes. However, at the boundaries of the range, the size of the bubbles was increased advising against use. Neutral pH values also favour the formation of small bubbles, and the presence of possible competing reactions have to be considered because they diminish the gas flow and affect the number of bubbles and their size. The roughness of the surface of the electrode material also has an important influence. CONCLUSIONS: The image acquisition and analysis system developed allows measurement of the size distribution of hydrogen bubbles in the range of current densities studied. Current density and pH seem to be the main parameters affecting the mean diameter of bubbles and the amount of gas produced, and the electrode material may also influence hydrogen production significantly. Copyright © 2010 Society of Chemical Industry [source]

Simulations of the active transport of a neutral solute based on a kinase-channel-phosphatase topology

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2005
K. Fiaty
Abstract Simulations of coupled interactions involving two opposite enzymatic reactions, solute diffusions, and electrostatic interactions between membrane charges and charged solutes were conducted under a fixed kinase-channel-phosphatase (KCP) topology oriented from the outside to the inside of a porous membrane structure. Depending on the kinase and phosphatase locations, we recently demonstrated that an active transport of a phosphorylated substrate may occur via the opposite topology, that is, a PCK topology. The present analysis demonstrates that, under a KCP membrane topology, which also behaves as a specific ATP-dependent transporter, the active transport of a neutral substrate may occur. This analogous active transport appears to be dependent on the phosphatase location and on the membrane surface potentials. A broad analysis of the role played by the main parameters taken into account in the model was conducted in order to define precisely the physico-chemical conditions and the membrane topology needed for the highest active transports within the shortest time. © 2004 Wiley Periodicals, Inc. J Comput Chem 26: 201,213, 2005 [source]

Intercultural Communication on Web sites: A Cross-Cultural Analysis of Web sites from High-Context Cultures and Low-Context Cultures

JOURNAL OF COMPUTER-MEDIATED COMMUNICATION, Issue 1 2005
Elizabeth Würtz
The aim of this study is to explore and identify the strategies used by high-context cultures in utilizing the Internet,a largely low-context medium,for communication and marketing purposes. It is hypothesized that individuals in high-context cultures are more likely to adopt the visual effects offered by the Internet to convey their messages efficiently than their low-context counterparts. How might high-context cultures make the most of the potentials offered by the Internet generation of today? Assuming that visual communication is a high priority in the design of high-context Web sites, how do the visual methods used on Web sites vary according to the communication styles in different cultures? Using Hall's high- and low-context dimensions as the main parameters, an exploratory analysis of McDonald's Web sites identified five different strategies by which visual communication is used to support high-context communication traits. [source]

Co-variation between the intensity of behavioural manipulation and parasite development time in an acanthocephalan,amphipod system

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 10 2010
N. FRANCESCHI
Abstract Pomphorhynchus laevis, a fish acanthocephalan parasite, manipulates the behaviour of its gammarid intermediate host to increase its trophic transmission to the definitive host. However, the intensity of behavioural manipulation is variable between individual gammarids and between parasite populations. To elucidate causes of this variability, we compared the level of phototaxis alteration induced by different parasite sibships from one population, using experimental infections of Gammarus pulex by P. laevis. We used a naive gammarid population, and we carried out our experiments in two steps, during spring and winter. Moreover, we also investigated co-variation between phototaxis (at different stages of infection, ,young' and ,old cystacanth stage') and two other fitness-related traits, infectivity and development time. Three main parameters could explain the parasite intra-population variation in behavioural manipulation. The genetic variation, suggested by the differences between parasite families, was lower than the variation owing to an (unidentified) environmental factor. Moreover, a correlation was found between development rate and the intensity of behavioural change, the fastest growing parasites being unable to induce rapid phototaxis reversal. This suggests that parasites cannot optimize at the same time these two important parameters of their fitness, and this could explain a part of the variation observed in the wild. [source]

Description and ontogeny of young Stolephorus baganensis and Thryssa kammalensis, two Engraulididae from Peninsular Malaysia

JOURNAL OF FISH BIOLOGY, Issue 6 2000
V. Sarpéadonti
The morphology of the digestive system was useful to distinguish the larvae of Stolephorus baganensis and Thryssa kammalensis before the full development of their dorsal and anal fins. The relative positions of these fins, the length of the anal fin, and body depth, were good criteria for identifying individuals >10·0 mm LS. For both species, the relative growth of the ten morphometric characters studied was best explained by linear piecewise regressions indicating inflection in allometry at specific standard lengths. Most of these sudden changes in growth rate occurred between 6·9 and 10·0 mm LS for S. baganensis and between 5·8 and 8·9 mm LS for T. kammalensis. Double-centred principal component analysis (PCA) confirmed important changes in the external morphology of both species during this transition period. Prior to this period, the main parameters characterizing the global morphological changes of both species were the length and position of dorsal and anal fins whereas they were body depth and eye diameter (only in S. baganensis) for larger specimens. Complete development of scales did not appear as a suitable criterion to define the end of the larval period, which, instead, was set at the size at which larvae presented an adult-like pigmentation (respectively 35·0 mm LS and 55·0 mm LS in S. baganensis and T. kammalensis). [source]

Yodel: A Yield Stress Model for Suspensions

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006
Robert J. Flatt
A model for the yield stress of particulate suspensions is presented that incorporates microstructural parameters taking into account volume fraction of solids, particle size, particle size distribution, maximum packing, percolation threshold, and interparticle forces. The model relates the interparticle forces between particles of dissimilar size and the statistical distribution of particle pairs expected for measured or log-normal size distributions. The model is tested on published data of sub-micron ceramic suspensions and represents the measured data very well, over a wide range of volume fractions of solids. The model shows the variation of the yield stress of particulate suspensions to be inversely proportional to the particle diameter. Not all the parameters in the model could be directly evaluated; thus, two were used as adjustable variables: the maximum packing fraction and the minimum interparticle separation distance. The values for these two adjustable variables provided by the model are in good agreement with separate determinations of these parameters. This indicates that the model and the approximations used in its derivation capture the main parameters that influence the yield stress of particulate suspensions and should help us to better predict changes in the rheological properties of complex suspensions. The model predicts the variation of the yield stress of particulate suspensions to be inversely proportional to the particle diameter, but the experimental results do not show a clear dependence on diameter. This result is consistent with previous evaluations, which have shown significant variations in this dependence, and the reasons behind the yield stress dependence on particle size are discussed in the context of the radius of curvature of particles at contact. [source]

Spiral patch with wideband and circular polarization for millimeter-wave communication

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
Wei He
Abstract In this study, a spiral patch antenna operating millimeter-wave band is proposed. Using this spiral structure, the patch antenna is designed for circular polarization and wideband operation at about 30.8,36.9 GHz for millimeter-wave communication. Simulated and measured results for main parameters such as return loss, impedance bandwidth, radiation patterns, and gains are also discussed herein. The study shows that the modeling of such antennas, with simplicity in designing and feeding, can well meet millimeter-wave wireless communication. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2068,2071, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22648 [source]

Analysis of , Librae including Hipparcos astrometry

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
V. Bak
ABSTRACT New spectroscopy of the classical Algol system , Lib, combined with high-quality optical and infrared photometry, provides the basis for a good understanding of the close binary system's main parameters. Detailed analysis of the photometry reveals the significant role of a third light source, pointing to the existence of a companion to the eclipsing system of mass ,1 M,. We review the methodology of applying high-accuracy positional information, available from the Hipparcos Intermediate Astrometric Data archive, to stars that may have such companions. Analysis of the astrometry of , Lib also points to a third star similar to the one already identified by Worek from radial-velocity data, although with slightly revised parameters. O,C data do not contradict this, but their general precision (while confirming the close pair's Algol status) fails to allow a decision on the third orbit parameters: Worek's or revised ones. Taking the photometry, spectroscopy and astrometry together, however, the existence of a third star of comparable mass to the Sun, as a relatively close companion to the eclipsing binary (,4 au), is confirmed. [source]

Application of fast-digitizer card Acqiris DP-240 in positron lifetime spectroscopy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2009
Martin Petriska
Abstract Based on the available knowledge base in positron annihilation measurements, new software for digital positron lifetime spectrometry has been designed within the frame of joint activity between STU Bratislava and JRC Petten. The tests of the new positron digital-life time setup have been carried out. Detectors with BaF2 scintillators and fast-dynode outputs were chosen for such studies. As the digitiser unit, the card Acqiris DP240 was fully tested. Originally, start and stop timing signals were sampled to digital waveforms separately at a rate of 1 GS/s in 8 bit resolution. However, due to limited quality of collected waveforms which significantly affected post-processing of data, the joined delayed channel mode with 2 GS/s sampling rate was applied for further studies. The full setup was benchmarked by a series of calibration measurements of two high purity materials, specifically Si and Ni. The inter-comparison of conventional analogue- and digital-based processing are discussed in detail. Further, the optimisation of main parameters for waveform-processing are analysed too. Such a new approach in the digital life-time spectroscopy will help to improve the resolution of existing methodology which might enhance the capabilities of this technique for further applications, especially in materials science. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Temperature acclimation in a biochemical model of photosynthesis: a reanalysis of data from 36 species

PLANT CELL & ENVIRONMENT, Issue 9 2007
JENS KATTGE
ABSTRACT The Farquhar et al. model of C3 photosynthesis is frequently used to study the effect of global changes on the biosphere. Its two main parameters representing photosynthetic capacity, Vcmax and Jmax, have been observed to acclimate to plant growth temperature for single species, but a general formulation has never been derived. Here, we present a reanalysis of data from 36 plant species to quantify the temperature dependence of Vcmax and Jmax with a focus on plant growth temperature, i.e. the plants' average ambient temperature during the preceding month. The temperature dependence of Vcmax and Jmax within each data set was described very well by a modified Arrhenius function that accounts for a decrease of Vcmax and Jmax at high temperatures. Three parameters were optimized: base rate, activation energy and entropy term. An effect of plant growth temperature on base rate and activation energy could not be observed, but it significantly affected the entropy term. This caused the optimum temperature of Vcmax and Jmax to increase by 0.44 °C and 0.33 °C per 1 °C increase of growth temperature. While the base rate of Vcmax and Jmax seemed not to be affected, the ratio Jmax : Vcmax at 25 °C significantly decreased with increasing growth temperature. This moderate temperature acclimation is sufficient to double-modelled photosynthesis at 40 °C, if plants are grown at 25 °C instead of 17 °C. [source]

Quantum dot-based protein micro- and nanoarrays for detection of prostate cancer biomarkers

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 9 2008
Anisha Gokarna
Abstract In this article, we demonstrate the fabrication and detection of cancer protein biochips consisting of micro- and nanoarrays whereby pegylated quantum dots (QDs) conjugated to antibodies (Abs) of prostate specific antigens (PSA) were used for the detection of clinical biomarkers such as PSA. BSA which acts as an efficient blocking layer in microarrays, tends to show an interaction with QDs. In view of this fact, we investigated two series of samples which were fabricated in the presence and absence of BSA blocking layer. Variation in the incubation time required for the antigen,antibody interaction to take place, different proteins as controls and the effect of bare QDs on these microarrays, were the three main parameters which were studied in these two series. Samples fabricated in the absence of BSA blocking layer exhibited an extremely high specificity in the detection of cancer proteins and were also marked by negligible nonspecific binding effects of QDs, in stark contrast to the samples fabricated using BSA as a blocking layer. Fabrication of nanoarrays of QD-conjugated PSA Abs having a spot size of nearly 900,nm has also been demonstrated. Thus, we show the potential offered by QDs in in vitro analysis of cancer biomarker imaging. [source]

Effects of Constant, 9 and 16-h Light Cycles on Sperm Quality, Semen Storage Ability and Motile Sperm Subpopulations Structure of Boar Semen

REPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2006
MM Rivera
Contents This study was performed to test the effect that two separate, daily, constant-light regimes of both 9 and 16 h could have on the main parameters of boar-semen quality analysis, as well as on the motile sperm subpopulations structure and the ability of its conservation at 16°C. Results show that both luminous regimes have slight, specific effects on the main parameters of boar-semen quality analysis, as well as on the motile sperm subpopulations structure. Furthermore, the conservation ability at 16°C of boar semen was not significantly different between both photoperiods. When a temporal study was performed, results showed that semen quality and motility parameter changes were stabilized at nearly constant values from the second month of the study to the last month in both luminous regimes, indicating a rapid light-related effect on testicular function. Our results indicate that light regimes oscillating from 9 h daily to 16 h daily are of little importance in the control of boar-semen quality in a farming environment. [source]