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Linear Relation (linear + relation)
Kinds of Linear Relation Selected AbstractsUltrasensitive Eletrogenerated Chemiluminescence Immunoassay by Magnetic Nanobead AmplificationELECTROANALYSIS, Issue 3 2010Mingyue Li Abstract An ultrasensitive electrogenerated chemiluminescence (ECL) immunoassay was proposed by using magnetic nanobeads (MNBs) as the carrier of ECL labels for ECL emission amplification. Carcinoembryonic antigen (CEA) and MNBs were initially immobilized on a platform in 1,:,1 molar ratio via sandwich immunoreaction. Subsequently, the MNBs were released from the platform and labeled with Ru(bpy)32+ species. After the MNBs with Ru(bpy)32+ were immobilized on an Au electrode, ECL of the Ru(bpy)32+ was measured for CEA determination. A linear relation between the ECL intensity and CEA concentration was obtained in a range of 1×10,14 to 3×10,13,mol/L (2.0 to 60,pg/mL) with a limit of detection of 8.0×10,15,mol/L (1.6,pg/mL). [source] Evaluation of poly(ethylene-co-vinyl acetate-co-carbon monoxide) and polydimethylsiloxane for equilibrium sampling of polar organic contaminants in waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Jörgen A Magnér Abstract Abstract-The aim of the present study was to develop a passive a bsorptive equilibrium sampler that would enable the determination of the concentrations of polar organic compound (POC) in water more efficiently than existing techniques. To this end, a novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated and the results were compared with an existing silicone-based passive absorptive equilibrium device. Seven compounds (imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon, and chlorpyrifos), a mixture of pharmaceuticals, and pesticides with a logarithmic octanol-water partition coefficient ranging from 0.2 to 4.77 were selected as model substances for the experiments. The results showed that six of the seven selected POCs reached distribution equilibrium within 4 d in the two materials tested. A linear relation with a regression coefficient of more than 0.8906 between the established logarithmic absorbent-water partition coefficient and the calculated logarithmic dissociation partition coefficient of the selected compounds in the two polymers was observed. The correlation between these two coefficients was within one order of magnitude for the compounds that reached equilibrium in the two polymers, which demonstrates that both materials are suitable for mimicking biological uptake of POCs. The PEVAC material showed an enhanced sorption for all selected compounds compared to the silicone material and up to five times higher enrichment for the most polar compound. Fluorescence analysis of the sampler cross-section, following the uptake of fluoranthene, and proof that the sorption was independent of surface area variations demonstrated that the PEVAC polymer possessed absorptive rather than adsorptive enrichment of organic compounds. [source] Copper toxicity in relation to surface water-dissolved organic matter: Biological effects to Daphnia magnaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2004Kees J.M. Kramer Abstract Water quality standards for copper are usually stated in total element concentrations. It is known, however, that a major part of the copper can be bound in complexes that are biologically not available. Natural organic matter, such as humic and fulvic acids, are strong complexing agents that may affect the bioavailable copper (Cu2+) concentration. The aim of this study was to quantify the relation between the concentration of dissolved natural organic matter and free Cu2+ in surface waters, and the biological effect, as measured in a standardized ecotoxicological test (48 h-median effective concentration [EC50] Daphnia magna, mobility). Six typical Dutch surface waters and an artificial water, ranging from 0.1 to 22 mg/L dissolved organic carbon (DOC), were collected and analyzed quarterly. Chemical speciation modeling was used as supporting evidence to assess bioavailability. The results show clear evidence of a linear relation between the concentration of dissolved organic carbon (in milligrams DOC/L) and the ecotoxicological effect (as effect concentration, EC50, expressed as micrograms Cu/L): 48-h EC50 (Daphnia, mobility) = 17.2 × DOC + 30.2 (r2 = 0.80, n = 22). Except for a brook with atypical water quality characteristics, no differences were observed among water type or season. When ultraviolet (UV)-absorption (380 nm) was used to characterize the dissolved organic carbon, a linear correlation was found as well. The importance of the free copper concentration was demonstrated by speciation calculations: In humic-rich waters the free Cu2+ concentration was estimated at ,10,11 M, whereas in medium to low dissolved organic carbon waters the [Cu2+] was ,10,10 M. Speciation calculations performed for copper concentrations at the effective concentration level (where the biological effect is considered the same) resulted in very similar free copper concentrations (,10,8 M Cu) in these surface waters with different characteristics. These observations consistently show that the presence of organic matter decreases the bioavailability, uptake, and ecotoxicity of copper in the aquatic environment. It demonstrates that the DOC content must be included in site-specific environmental risk assessment for trace metals (at least for copper). It is the quantification of the effects described that allows policy makers to review the criteria for copper in surface waters. [source] Lateralised motor behaviour leads to increased unevenness in front feet and asymmetry in athletic performance in young mature Warmblood horsesEQUINE VETERINARY JOURNAL, Issue 5 2010M. C. V. Van HEEL Summary Reason for performing study: Foot stance in grazing significantly influences hoof conformation and development from foal to yearling age. Objectives: To conduct a longitudinal study to establish if the relationship between motor laterality and uneven front feet persisted in 3-year-old horses at the time of studbook selection and to investigate if such laterality and unevenness might influence the horses' ability to perform symmetrically while trotting, cantering and free jumping. Methods: Seventeen clinically sound but untrained (with only minimal experience of handling) and sound Warmblood horses that had participated in a previous study were assessed as per the protocol reported. Laterality was tested in a preference test (PT) and z -values were calculated for analysis purposes. Laterality and hoof unevenness were related to both relative limb length and relative head size, while the ability to perform symmetrically was tested in free trot-canter transitions and free jumping exercises. Differences in performance between horses with and without a limb preference in the PT and those with ,uneven' and ,even' feet were tested for differences in performance metrics using Students' t test, while linearity was tested using a regression analysis (P<0.05). Results: Significant laterality was still present in 24% of the 3-year-old horses and the relationship between laterality and uneven feet pairs was stronger than at foal and yearling stages. Horses with significant motor laterality had almost 4 times more unevenness, a smaller head and longer limbs and the relationship between body conformation and laterality was still present. There was a strong linear relation between unevenness, laterality and a bias or side preference for trot-canter transitions. However, this relationship was not significant during the free jumping exercise. Conclusion: Motor laterality and uneven feet pairs were still present and significantly related in the 3-year-old horses and both variables were also strongly related to sidedness in trot-canter transitions. Potential relevance: Warmblood studbooks should include quantitative data on laterality at the time of studbook admission as part of the selection criteria. [source] Calorimetric study of milk fat/rapeseed oil blends and their interesterification productsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 4 2009Mario Aguedo Abstract Milk fat (MF) and rapeseed oil (RO) blends were analyzed by differential scanning calorimetry (DSC). It was shown that peak and onset temperatures can be used to determine the percentage of each fat in the blend and that the relative enthalpy of one peak assigned to low-melting triacylglycerols (TAG) can also be used to determine the percentage of RO in the blend. A linear relation was also established between MF content of the blend and its dropping point (DP), indicating that DP can be linearly related with the above DSC data. A blend of MF/RO 70,:,30 (wt/wt) was then chosen as a model system for enzymatic interesterification (EIE). The applicability of DSC analyses to EIE products was checked and a correct correlation could be established between DSC values and the interesterification degree and DP. Among the data from the DSC profiles, the peak associated with low-melting TAG was the best indicator of the reaction course. In the same way, a high-melting MF stearin fraction was interesterified with RO. In that case, onset temperatures and peak "a" were better reaction indicators than for the interesterified MF/RO blend. We therefore suggest that values from DSC endotherms could be used to monitor EIE of fat blends. [source] Spawning habitat and daily egg production of sardine (Sardina pilchardus) in the eastern MediterraneanFISHERIES OCEANOGRAPHY, Issue 4 2006S. SOMARAKIS Abstract Spawning habitats of two eastern Mediterranean sardine, Sardina pilchardus (Walbaum, 1792), stocks (coastal waters of central Aegean and Ionian Seas) are characterized from daily egg production method (DEPM) surveys conducted during the peak of the spawning period. The latter occurs earlier in the Aegean Sea (December) than in the less-productive Ionian Sea (February). Single-parameter quotient analysis showed that the preferred bottom depth for spawning was 40,90 m in both areas but sardine selected sites of increased zooplankton in the Aegean Sea during December and increased fluorescence in the Ionian Sea during February. Estimates of daily egg production (P) and spawning stock biomass (B) were about four times lower for the Ionian Sea (P = 7.81 eggs m,2, B = 3652 tonnes) than the Aegean Sea (P = 27.52 eggs m,2, B = 16 174 tonnes). We suggest that zooplankton biomass might not be sufficient to support sardine reproduction in the highly oligotrophic Ionian Sea where the very small sardine stock may rely on the late-winter phytoplankton bloom. Actively selecting sites with increased zooplankton or phytoplankton and feeding plasticity (the well-known switching from selective particle feeding to non-selective filter feeding in sardines) are interpreted as adaptations to grow and reproduce optimally at varying prey conditions. Despite differences in temperature and productivity regimes, reproductive performance of sardine in the Ionian Sea was very similar to that in the Aegean Sea during the peak of the spawning period. In comparing adult parameters from DEPM applications to Sardina and Sardinops stocks around the world, a highly significant linear relation emerged between mean batch fecundity (F) and mean weight of mature female (W, g) (F = 0.364W, r2 = 0.98). The latter implies that, during the peak of the spawning period, mean relative batch fecundity (eggs g,1) of sardine is fairly constant in contrasting ecosystems around the world. [source] Sequential integrated inversion of refraction and wide-angle reflection traveltimes and gravity data for two-dimensional velocity structuresGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2000Rosaria Tondi A new algorithm is presented for the integrated 2-D inversion of seismic traveltime and gravity data. The algorithm adopts the ,maximum likelihood' regularization scheme. We construct a ,probability density function' which includes three kinds of information: information derived from gravity measurements; information derived from the seismic traveltime inversion procedure applied to the model; and information on the physical correlation among the density and the velocity parameters. We assume a linear relation between density and velocity, which can be node-dependent; that is, we can choose different relationships for different parts of the velocity,density grid. In addition, our procedure allows us to consider a covariance matrix related to the error propagation in linking density to velocity. We use seismic data to estimate starting velocity values and the position of boundary nodes. Subsequently, the sequential integrated inversion (SII) optimizes the layer velocities and densities for our models. The procedure is applicable, as an additional step, to any type of seismic tomographic inversion. We illustrate the method by comparing the velocity models recovered from a standard seismic traveltime inversion with those retrieved using our algorithm. The inversion of synthetic data calculated for a 2-D isotropic, laterally inhomogeneous model shows the stability and accuracy of this procedure, demonstrates the improvements to the recovery of true velocity anomalies, and proves that this technique can efficiently overcome some of the limitations of both gravity and seismic traveltime inversions, when they are used independently. An interpretation of field data from the 1994 Vesuvius test experiment is also presented. At depths down to 4.5 km, the model retrieved after a SII shows a more detailed structure than the model obtained from an interpretation of seismic traveltime only, and yields additional information for a further study of the area. [source] Design Rules for Donors in Bulk-Heterojunction Solar Cells,Towards 10,% Energy-Conversion Efficiency,ADVANCED MATERIALS, Issue 6 2006C. Scharber For bulk-heterojunction photovoltaic cells fabricated from conjugated polymers and a fullerene derivative, the relation between the open-circuit voltage (Voc) and the oxidation potential for different conjugated polymers is studied. A linear relation between Voc and the oxidation potential is found (see figure). Based on this relation, the energy-conversion efficiency of a bulk-heterojunction solar cell is derived as a function of the bandgap and the energy levels of the conjugated polymer. [source] Degradation of aramid fibers under alkaline and neutral conditions: Relations between the chemical characteristics and mechanical propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010G. Derombise Abstract Aramid fibers are high-performance materials that have been used in various applications such as heat and cut protection, composites, rubber reinforcement, ropes and cables, and fabrics; today their use is proposed in geotextiles for alkaline ground reinforcement, and they have been used in cables for marine applications for a few years. However, there is a lack of experience with the long-term behavior of aramid fibers in wet and alkaline environments. Aging studies were therefore performed on Twaron 1000 fibers under different conditions (sea water, deionized water, pH 9, and pH 11). Hydrolytic degradation was evaluated with Fourier transform infrared and viscosimetry measurements, which were correlated with tensile test measurements. The tensile strength followed a logarithmic evolution with the aging time, whereas the modulus remained constant. A linear relation between the tensile strength and the reduced viscosity of the hydrolytically aged fibers is highlighted. Aging indicators are proposed that allow the hydrolytic degradation to be quantified. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Modeling of the Cod Desalting OperationJOURNAL OF FOOD SCIENCE, Issue 4 2004J. M. Barat ABSTRACT: The objective of this study was to apply mathematical expressions commonly used in the analysis of mass-transfer processes to the study of the cod desalting operation to be able to predict the changes suffered by cod during the process. The NaCl concentration in the cod liquid phase at equilibrium was well predicted by using a mass balance. It was observed that the changes in the cod liquid phase concentration and the total weight changes throughout the process could be predicted by using a pseudo-diffusional approach or a biexponential equation, whereas a linear relation was observed between the NaCl cod liquid phase concentration and the cod density. [source] Pulmonary Venous Wedge Pressure Provides an Accurate Assessment of Pulmonary Artery Pressure in Children with a Bidirectional Glenn ShuntJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2003DANIEL H. GRUENSTEIN M.D. Purpose: In circulations with pulsatile pulmonary artery flow the pulmonary venous wedge pressure (PVWp) has been validated as a good estimate of pulmonary artery pressure (PAp), when PAp is low. The purpose of this study was to validate PVWp estimates of PAp in the less-pulsatile pulmonary circulation of children after bidirectional Glenn shunts. Methods: A retrospective study was performed of 22 simultaneous measurements of PVWp and PAp made during 20 catheterizations in 19 children who had undergone bidirectional Glenn procedures. The PAp was measured directly from the branch PA ipsilateral to the side of the PVWp, or in the SVC. Pulmonary resistance (Rp) was calculated with both PAp and PVWp, to assess the impact of PAp estimates on Rp determinations. Results: Patients ranged in age from 5 months to 10.7 years. There were a variety of univentricular cardiac malformations in the study group. Two children had antegrade pulmonary blood flow in addition to a bidirectional Glenn shunt. The mean PAp ranged from 4 to 14 mmHg, while mean PVWp ranged from 3 to 15 mmHg. Mean PVWp never differed from mean PAp by more than 3 mmHg. There was a significant linear relation between mean PAp and PVWp: PAp = 0.86 (PVWp) + 2.0 (R2= 0.89; P < 0.0001). PVWp provided a good approximation of PAp regardless of the presence (n = 2) or absence (n = 19) of antegrade pulmonary flow. There was a good linear correlation between the Rp calculated by both methods (RpPAp = 0.9 (RpVWp) + 0.5; R2= 0.74; P < 0.0001). Conclusion: The mean PVWp provides a close approximation of mean PAp in children with a bidirectional Glenn shunt and provides valuable hemodynamic information in cases where direct PAp measurements are unavailable. (J Interven Cardiol 2003;16:367,370) [source] Measuring anisotropic thermal conduction in polyisobutylene following step shear strainsAICHE JOURNAL, Issue 3 2000Hadjira Iddir The connection between polymer chain orientation and several macroscopic properties in a polymer melt was studied using mechanical and optical techniques. Anisotropic thermal conductivity following shear deformation was measured using forced Rayleigh light scattering, the refractive index tensor is followed using birefringence measurements, and the stress was measured mechanically in a parallel-plate rheometer. The thermal diffusivity measured in the flow and neutral directions increased and decreased, respectively, immediately following the deformation. These quantities then relaxed to the equilibrium value on the time-scale of the stress-relaxation memory. Comparison of the difference between measured flow and neutral direction thermal diffusivities with the analogous flow-induced birefringence in the same deformation provided indirect evidence for a linear relation between stress and thermal diffusivity at two different values of strain. Mechanical measurements were used to characterize the memory of the fluid. [source] Use of highly energetic (116,keV) synchrotron radiation for X-ray fluorescence analysis of trace rare-earth and heavy elementsJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2001Izumi Nakai This study has revealed the advantages of the use of 116,keV X-rays as an excitation source of X-ray fluorescence (XRF) analyses. This technique is suitable for nondestructive multielemental analyses of heavy elements such as rare-earth elements. The lowest MDL value evaluated for the bulk analysis of a JG-1 standard reference sample (granite rock) was 0.1 p.p.m. for W for a 500,s measurement. The spectrum of standard glass samples of SRM612 demonstrated clearly resolved K -line peaks of more than 30 elements, including all the existing rare-earth elements, at 50 p.p.m. levels. The calibration curve for the determination of a rare-earth element shows a linear relation between the XRF intensity and concentrations from 10 to 0.03,ng. This powerful technique should be useful for nondestructive analyses of rare-earth and heavy elements in geological, geochemical and archaeological samples as well as industrial materials. [source] Inspection of Remanent Polarization in the Ferroelectric Ceramic PZT 95/5 Through Pyroelectric EffectJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007Fu-Ping Zhang Shock-induced depoling of the ferroelectric (FE) ceramic PZT 95/5 is utilized in a number of pulsed power devices. Nondestructive testing of remanent polarization of PZT 95/5 is developed by pyroelectric effect in this paper. Approximately linear relation between the change of polarization during low- to high-temperature rhombohedral FE phase and the remanent polarization was found through pyroelectricity of a single piece of PZT 95/5 ceramics. The change of polarization of a prototype for shock-driven pulsed power during the FEHT,FELT phase transformation was also investigated through directly measuring the pyroelectric current. Results indicate that pyroelectric effect caused by the reversible FEHT,FELT phase transition could be used as a non-destructive inspection for the remanent polarization of a prototype about shock-driven pulsed power supply. [source] New relations between similarity measures for vectors based on vector normsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 2 2009Leo Egghe The well-known similarity measures Jaccard, Salton's cosine, Dice, and several related overlap measures for vectors are compared. While general relations are not possible to prove, we study these measures on the "trajectories" of the form , where a > 0 is a constant and ||·|| denotes the Euclidean norm of a vector. In this case, direct functional relations between these measures are proved. For Jaccard, we prove that it is a convexly increasing function of Salton's cosine measure, but always smaller than or equal to the latter, hereby explaining a curve, experimentally found by Leydesdorff. All the other measures have a linear relation with Salton's cosine, reducing even to equality, in case a = 1. Hence, for equally normed vectors (e.g., for normalized vectors) we, essentially, only have Jaccard's measure and Salton's cosine measure since all the other measures are equal to the latter. [source] The oxygen vacancy in Ga2O3: a double resonance investigation,MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2005H. J. Kümmerer Abstract When produced under reducing conditions, ,-Ga2O3 is transformed into an n -type semiconductor with delocalized conduction electrons that exhibit a very strong electron spin resonance (ESR) and a strong hyperfine coupling to the gallium nuclei of the host lattice. We apply the Overhauser-shift technique to investigate single crystals of this compound. With extension to the high magnetic field of a W-band spectrometer, we were able to resolve all spectral lines that were recorded and to assign them to their corresponding electronic and nuclear states. This separate analysis was the basis to access additional sample characteristics: the hyperfine coupling that is actually averaged out in the ESR signal, as well as the nuclear relaxation rates could be analyzed. Systematic measurements by varying the microwave power revealed the Overhauser shift in thermal equilibrium. The signal could be tracked to very small microwave saturation parameters, at which the deviation from the usual linear relation between power and shift becomes evident and the shift clearly approaches a constant value. This value in equilibrium was determined directly from a fit to a sequence of measurements, whereas standard X-band experiments only provided indirect conclusions. The probability densities of the electrons at the nuclei in the two nonequivalent crystallographic positions,the lattice sites with octahedral and tetrahedral coordination,could also be determined directly. The enhanced resolution revealed an otherwise hidden substructure in the nuclear resonance signals. On the basis of a microscopic model, this structure could be used to probe the environment of the oxygen vacancy more precisely and to determine the extension of the electronic wave function of the donor electrons. Copyright © 2005 John Wiley & Sons, Ltd. [source] Influence of heat impact in reconstituted skim milk on the properties of yoghurt fermented by ropy or non-ropy starter culturesMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 5 2003Peter Chr. Abstract The paper describes studies on the influence of heat impact in reconstituted skim milk on chemical and functional properties of yoghurt products. Reconstituted skim milk was heated for 20 min at 85°C, 90°C, or 95°C. Ropy (producing exopolysaccharides, EPS) or non-ropy strains of S. thermophilus and L. delbrueckii subsp. bulgaricus were used as starter culture for yoghurt manufacture. The studies have shown that the fermentation times decreased with increasing heat impact when the ropy starter culture was used, while they remained to a far extent unchanged if the non-ropy starter culture was applied. The lactic acid contents of the yoghurt products were in the same range when the milk was heated at 85°C or 90°C, while they were different when milk was heated at 95°C. There was a tendency visible that an increase in preheating leads to increased L(+)- and decreased D(,)-lactic acid contents if the non-ropy culture was applied. Using the ropy culture, it was vice versa. A slightly decrease in proteolysis with increasing heat impact was to be noted with both starter cultures. Concerning the relation of proteolysis to acidification, the fermentation process could be subdivided into three sections with different slopes if the non-ropy starter culture was used, while a linear relation was found if the ropy starter culture was applied. Regarding final product characteristics it was found that the functional properties of yoghurt decreased with increasing heat impact when the ropy starter culture was applied, while they remained to a far extent unchanged when the non-ropy starter culture was used. It can be concluded from these studies that a preheating of milk at a temperature of 85°C (20 min) is optimal in regard to final yoghurt product characteristics. [source] An intriguing correlation between the masses and periods of the transiting planetsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005Tsevi Mazeh ABSTRACT We point out an intriguing relation between the masses of the transiting planets and their orbital periods. For the six currently known transiting planets, the data are consistent with a decreasing linear relation. The other known short-period planets, discovered through radial-velocity techniques, seem to agree with this relation. We briefly speculate about a tentative physical model to explain such a dependence. [source] Steady-State versus Non-Steady-State QT-RR Relationships in 24-hour Holter RecordingsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2000GILLES LANDE The aim of the present study was to investigate the QT-RR interval relationship in ambulatory ECG recordings with special emphasis on the physiological circumstances under which the QT-RR intervals follow a linear relation. Continuous ECG recordings make it possible to automatically measure QT duration in individual subjects under various physiological circumstances. However, identification of QT prolongation in Holter recordings is hampered by the rate dependence of QT duration. Comparison of QT duration and QT interval rate dependence between different individuals implies that the nature of the QT-RR relationship is defined in ambulatory ECG. Holter recordings were performed in healthy volunteers at baseline and after administration of dofetilide, a Class III antiarrhythmic drug. After dofetilide, beat-to-beat automated QT measurements on Holter tapes were compared with manually measured QT intervals on standard ECGs matched by time. The QT-RR relationship was analyzed at baseline in individual and group data during three different periods: 24-hour, daytime, and nighttime. Data were collected under steady-state or non-steady-state conditions of cycle length and fitted with various correction formulae. Our study demonstrated an excellent agreement between manually and automated measurements. The classic Bazett correction formula did not fit the QT-RR data points in individual or group data. When heart beats were selected for a steady rhythm during the preceding minute, QT-RR intervals fit a linear relationship during the day and night periods, but not during the 24-hour period in both individual and group data. In contrast, in the absence of beat selection, data fit a more complex curvilinear relationship irrespective of the period. Our study provides the basis for comparison of QT interval durations and QT-RR relationships between individuals and between groups of subjects. [source] Simple determination of the herbicide napropamide in water and soil samples by room temperature phosphorescencePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2005Alfonso Salinas-Castillo Abstract A new, simple, rapid and selective phosphorimetric method for determining napropamide is proposed which demonstrates the applicability of heavy-atom-induced room-temperature phosphorescence for analyzing pesticides in real samples. The phosphorescence signals are a consequence of intermolecular protection and are found exclusively with analytes in the presence of heavy atom salts. Sodium sulfite was used as an oxygen scavenger to minimize room-temperature phosphorescence quenching. The determination was performed in 1 M potassium iodide and 6 mM sodium sulfite at 20 °C. The phosphorescence intensity was measured at 520 nm with excitation at 290 nm. Phosphorescence was easily developed, with a linear relation to concentration between 3.2 and 600.0 ng ml,1 and a detection limit of 3.2 ng ml,1. The method has been successfully applied to the analysis of napropamide in water and soil samples and an exhaustive interference study was also carried out to display the selectivity of the proposed method. Copyright © 2005 Society of Chemical Industry [source] Origins of n-type residual carriers in RF-MOMBE grown InN layersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007Kosuke Iwao Abstract We have investigated quantitatively on the origins of residual electrons in InN layers to make clear some roles of oxygen incorporation for band-gap widening. It has been found out that a linear relation was observed between oxygen and residual electron concentrations for InN layers grown by RF-MOMBE using TMIn source, although the residual electron concentration is super-linearly dependent on oxygen concentration for InN layers grown by RF-MBE using metal In source. The experimental results strongly indicate that oxygen atoms and/or nitrogen vacancies induced by oxygen incorporation are major origins of the residual carrier concentrations. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Contributions of Political Life Events to Psychological Distress Among South AfricanPOLITICAL PSYCHOLOGY, Issue 3 2000Michelle Slone The psychological consequences of adverse political experiences among South African youth were studied in a sample of 540 black and white adolescents from two age groups, evenly divided by gender. Three questionnaires were administered, measuring exposure to political life events, the presence of symptoms of psychopathology, and stressful personal life events during the previous 5 years. The first hypothesis, predicting a substantial contribution of stressful political experiences to psychopathology, was strongly supported; when stressful personal life events were partialed out, a significant effect for political life events remained both on general distress and symptomatology indices. The second hypothesis of a linear relation between exposure to political life events and severity of distress was also confirmed. The findings underscore the enduring impact on children's mental health of past apartheid policies in South Africa specifically, and adverse political environments in general. [source] Influence of fibre length and filler particle size on pore structure and mechanical strength of filler-containing paperTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2000Noriyoshi Kinoshita Abstract Test sheets were prepared by incorporating softwood pulp with silica filler, PW-5 (diameter 4.5 ,m) or PW-20 (15 ,m). Length-weighted averages of fibre were 2.5 (uncut fibre) and 1.25 mm (short-cut fibre). Pore sizes less than 150 urn were measured by mercury porosimeter. Sheets of short-cut fibres and mixed with uncut fibres at ratio of 3:1 or 1:3 had larger pore volumes than others tested. When filler content increased, the total pore volume increased for PW-20 sheets, but it did not for PW-5 sheets with short-cut fibres. Tensile index and folding endurance were very much affected by fibre length. Contact number on a fibre was calculated by computer simulation, and it had a linear relation with tensile index of sheet. Des échantillons de feuilles ont été préparés en incorporant dans de la pâte de bois tendre une charge de silice, soit du PW-5 (diamètre 4,5 ,m) ou du PW-20 (15 ,n). Les moyennes pondérées de la longueur des fibres sont de 2,5 (fibre non coupée) et 1,25 mm (fibre courte). Des distributions de taille des pores inférieures à 150 ,m ont été mesurées à l'aide d'un porosimètre au mercure. Les feuilles fabriquées avec des fibres courtes et celles mélangées à des fibres non coupees dans des rapports de 3:1 et 1:3 présentent de plus grands volumes de pores que les autres. Lorsque la charge augmente, le volume total des pores augmente pour les feuilles ayant du PW-20, ce qui n'est pas le cas pour les feuilles contenant du PW-5 avec des fibres courtes. L'indice de traction et l'endurance au pliage sont très influencés par la longueur des fibres. Le nombre de contacts sur une fibre a été calculé au moyen de simulations par ordinateur et il varie linéairement avec l'indice de traction des feuilles. [source] The CBOE S&P 500 three-month variance futuresTHE JOURNAL OF FUTURES MARKETS, Issue 1 2010Jin E. Zhang In this article, we study the market of the Chicago Board Options Exchange S&P 500 three-month variance futures that were listed on May 18, 2004. By using a simple mean-reverting stochastic volatility model for the S&P 500 index, we present a linear relation between the price of fixed time-to-maturity variance futures and the VIX2. The model prediction is supported by empirical tests. We find that a model with a fixed mean-reverting speed of 1.2929 and a daily-calibrated floating long-term mean level has a good fit to the market data between May 18, 2004, and August 17, 2007. The market price of volatility risk estimated from the 30-day realized variance and VIX2 has a mean value of ,19.1184. © 2009 Wiley Periodicals, Inc. Jrl Fut Mark 30:48,70, 2010 [source] Studies on the Acute Toxicity, Pharmacokinetics and Pharmacodynamics of Paliperidone Derivatives , Comparison to Paliperidone and Risperidone in Mice and RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2010Fengying Sun The i.g. LD50 and i.v. maximum tolerated doses of PD1, PD5 and PD6 were greater than those of paliperidone and risperidone in mice. Pharmacokinetic study showed that PDs were quickly metabolized to paliperidone to take effect in the treatment of schizophrenia in rats after i.g. administration. Only traces of the parent substances were found. Pharmacodynamic study showed that PDs significantly reduced MK-801-induced hyperlocomotion in mice. The electrocardiogram (ECG) was recorded at 0, 5, 10, 15, 20, 25, 30, 45 and 60 min. in anaesthetized rats after i.v. injection of 0.21, 0.59, 1.69 ,mol/kg drugs. Heart rate reduction had a linear relation with dose after i.v. injection of PDs, paliperidone and risperidone. No significant change in the ECG parameters was found in all groups after administration of the low dose. Although the reductions in heart rate and the corrected QT interval (QTc) were observed in all drugs at the high dose, PD5 and PD6 were associated with smaller effects on the ECG parameters than other compounds, including paliperidone and risperidone. Therefore, PD5 and PD6 could be potential candidates for the treatment of schizophrenia. [source] Development of a system for the on-line measurement of carbon dioxide production in microbioreactors: Application to aerobic batch cultivations of Candida utilisBIOTECHNOLOGY PROGRESS, Issue 3 2009Michiel van Leeuwen Abstract We developed and applied a conductometric method for the quantitative online measurement of the carbon dioxide (CO2) production during batch cultivations of Candida utilis on a 100-,L scale. The applied method for the CO2 measurement consisted of absorption of the produced CO2 from the exhaust gas of the microbioreactor in an alkali solution, of which the conductivity was measured on-line. The measured conductivity change of the alkali solution showed a linear relation with the total amount of CO2 absorbed. After calibration of the CO2 measurement system, it was connected to a well of a 96-well microtiter plate. The mixing in the well was achieved by a magnetic stirrer. Using online measurement of the CO2 production during the cultivation, we show reproducible exponential batch growth of C. utilis on a 100-,L scale. The CO2 production measurements obtained from the microcultivation were compared with the CO2 production measurement in a 4-L bioreactor equipped with a conventional off-gas analyzer. The measurements showed that on-line measurement of the CO2 production rate in microbioreactors can provide essential data for quantitative physiological studies and provide better understanding of microscale cultivations. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] The risk of preterm delivery in women from different ethnic groupsBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 8 2002Paul Aveyard Objective To examine whether routinely measured variables explained the increased risk of preterm delivery in some UK ethnic groups. Design Cross sectional study of deliveries recorded in the Child Health Record System. Setting North Birmingham, UK. Population All North Birmingham women delivering singletons, 1994,1997 inclusive. Method Logistic regression. Main outcome measures Odds ratio (OR) and 95% confidence interval (CI) for preterm delivery, defined as less than 37 weeks, less than 34 weeks and less than 28 weeks, unadjusted and adjusted for maternal age, an area-based socio-economic status measure, and marital status, year of birth, fetal sex and past obstetric history. Results For Afro-Caribbean women, the ORs (95% CIs) were: for delivery less than 37 weeks, 1.44 (1.26,1.64) unadjusted and 1.22 (1.07,1.41) adjusted; for delivery less than 34 weeks, 1.55 (1.25,1.92) unadjusted and 1.29 (1.02,1.61) adjusted; for delivery less than 28 weeks, 1.66 (1.08,2.55) unadjusted and 1.32 (0.84,2.06) adjusted. For African women, the risk of delivery less than 37 weeks was not significantly raised; for delivery less than 34 weeks, the OR (95% CI) was 1.88 (0.99,3.58) unadjusted and 1.78 (0.93,3.40) adjusted; for delivery less than 28 weeks, the OR (95% CI) was 4.02 (1.60,10.12) unadjusted and 4.10 (1.66,10.16) adjusted. In Afro-Caribbeans, deprivation and marital status explained the differences between the unadjusted and adjusted ORs. There was a linear relation between deprivation and preterm delivery for all ethnic groups, except for Asians. Conclusions Factors associated with deprivation and marital status explain about half of the excess of preterm births in Afro-Caribbeans, but not Africans. The risk of preterm delivery might not be related to deprivation in Asians. [source] Resonance Structures of the Amide Bond: The Advantages of PlanarityCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2006Jon I. Mujika Abstract Delocalization indexes based on magnitudes derived from electron-pair densities are demonstrated to be useful indicators of electron resonance in amides. These indexes, based on the integration of the two-electron density matrix over the atomic basins defined through the zero-flux condition, have been calculated for a series of amides at the B3LYP/6-31+G* level of theory. These quantities, which can be viewed as a measure of the sharing of electrons between atoms, behave in concordance with the traditional resonance model, even though they are integrated in Bader atomic basins. Thus, the use of these quantities overcomes contradictory results from analyses of atomic charges, yet keeps the theoretical appeal of using nonarbitrary atomic partitions and unambiguously defined functions such as densities and pair densities. Moreover, for a large data set consisting of 24 amides plus their corresponding rotational transition states, a linear relation was found between the rotational barrier for the amide and the delocalization index between the nitrogen and oxygen atoms, indicating that this parameter can be used as an ideal physical-chemical indicator of the electron resonance in amides. [source] Preschool Children's Mapping of Number Words to Nonsymbolic NumerositiesCHILD DEVELOPMENT, Issue 5 2005Jennifer S. Lipton Five-year-old children categorized as skilled versus unskilled counters were given verbal estimation and number word comprehension tasks with numerosities 20,120. Skilled counters showed a linear relation between number words and nonsymbolic numerosities. Unskilled counters showed the same linear relation for smaller numbers to which they could count, but not for larger number words. Further tasks indicated that unskilled counters failed even to correctly order large number words differing by a 2 : 1 ratio, whereas they performed well on this task with smaller numbers, and performed well on a nonsymbolic ordering task with the same numerosities. These findings provide evidence that large, approximate numerosity representations become linked to number words around the time that children learn to count to those words reliably. [source] Prevalence of immunoglobulin E for fungi in atopic childrenCLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2001G. Nolles Background The prevalence of sensitization to fungi in young atopic patients in relation to age and clinical importance is largely unknown. Objective The aim of this study was to investigate the prevalence of sensitization to different fungi in atopic children in relation to age and other aeroallergens. Methods A total of 137 atopic children (male 62%, female 38%; mean age 5 years and 9 months, range 5 months,14 years) were studied. Sera of all patients were routinely tested for total IgE and specific IgE against aeroallergens and milk. Positive sera were also tested for IgE against Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum and Penicillium chrysogenum, using the Pharmacia Enzyme CAP procedure. Results In this study in atopic children total IgE showed a significant linear relation with age, whereas specific IgE against outdoor fungi, indoor fungi and house dust mite showed significant non-linearity with age. Prevalence of specific IgE for Cladosporium ranked first, followed closely by Aspergillus and Alternaria. Calculation of the sensitization of indoor and outdoor fungi showed maximum prevalence at 7.8 years, followed by lower values at higher ages. A similar significant relation was also found for Alternaria, while this relation was not significant for the other individual fungi. Specific IgE for indoor and outdoor fungi was associated with the presence of specific IgE for aeroallergen and milk. We found that all children aged 4 years and older showed IgE for house dust mite that did not decline with increasing age. Conclusions Sensitization to fungi is prevalent in childhood, with an age-dependent distribution reaching maximum values at 7.7,7.8 years, followed by a decline for all fungal sensitization with increasing age. The importance and relative contribution of fungal sensitization to airway disease, compared with the other allergens, remains to be established. 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