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Quantitative Comparison (quantitative + comparison)

Distribution by Scientific Domains

Medical Sciences	22%
Life Sciences	22%
Chemistry	22%
Earth and Environmental Science	10%
Engineering	7%
Information Science and Computing	5%
4 Other Domains	12%

Selected Abstracts

Quantitative Comparison of Approximate Solution Sets for Bi-criteria Optimization Problems,

DECISION SCIENCES, Issue 1 2003
W. Matthew Carlyle
ABSTRACT We present the Integrated Preference Functional (IPF) for comparing the quality of proposed sets of near-pareto-optimal solutions to bi-criteria optimization problems. Evaluating the quality of such solution sets is one of the key issues in developing and comparing heuristics for multiple objective combinatorial optimization problems. The IPF is a set functional that, given a weight density function provided by a decision maker and a discrete set of solutions for a particular problem, assigns a numerical value to that solution set. This value can be used to compare the quality of different sets of solutions, and therefore provides a robust, quantitative approach for comparing different heuristic, a posteriori solution procedures for difficult multiple objective optimization problems. We provide specific examples of decision maker preference functions and illustrate the calculation of the resulting IPF for specific solution sets and a simple family of combined objectives. [source]

Censusing and Measuring Lianas: A Quantitative Comparison of the Common Methods,

BIOTROPICA, Issue 5 2006
Stefan A. Schnitzer
ABSTRACT Lianas contribute to many aspects of tropical forest diversity and dynamics, and interest in liana ecology has grown substantially in recent years. Methods to census lianas and estimate biomass, however, differ among studies, possibly hindering attempts to compare liana communities. At Nouragues Research Station (French Guiana), we tested the extent to which liana abundance, basal area, and estimated biomass differed depending on stem diameter measurement location, inclusion of ramets, inclusion of lianas rooted within versus passing through the plot, and plot shape. We found that the mean per plot abundance and basal area of lianas were significantly greater when lianas were measured low on the stem, when ramets were included, and when lianas were sampled in transects (2 × 50 m) than in square plots (10 × 10 m). Mean per plot liana abundance and basal area were 21 percent and 58 percent greater, when stems were measured at the largest spot on the stem compared to 130 cm from the ground, respectively. Including liana ramets increased average per plot liana abundance, basal area, and estimated biomass by 19, 17, and 16 percent, respectively. To facilitate cross-study comparisons, we developed conversion equations that equate liana abundance, diameter, and basal area based on the measurements taken at four different stem locations. We tested these equations at Lambir Hills National Park, Malaysia and found that they did not differ significantly between the two sites, suggesting that the equations may be broadly applicable. Finally, we present a new allometric equation relating diameter and biomass developed from 424 lianas from five independent data sets collected in four countries. RÉSUMÉ Les lianes contribuent de diverse manière à la diversité et à la dynamique des forêts tropicales, et l'intérêt pour l'écologie des lianes s'est beaucoup accru ces dernières années. Cependant, les méthodes pour recenser les lianes et estimer leur biomasse varient d'une étude à l'autre, et peuvent entraver les tentatives de comparaison des communautés de lianes. A la Station de Recherche des Nouragues (Guyane Française), nous avons évalué la variation de l'abondance, de la surface terrière et de la biomasse des lianes, en fonction de la position de mesure du diamètre sur le tronc, de l'inclusion des rameaux, de l'inclusion des lianes enracinées dans la parcelle plutôt que passant dans la parcelle, et de la forme de la parcelle. Nous avons trouvé que l'abondance et la surface terrière moyennes des lianes par parcelle étaient significativement plus importantes lorsque les lianes étaient mesurées en bas de la tige, lorsque les rameaux étaient inclus, et lorsque les lianes étaient échantillonnées dans des transects (2x50m) plutôt que dans des parcelles carrées (10x10m). L'inclusion des rameaux dans l'échantillonnage augmentait l'abondance moyenne des lianes par parcelle de 19 pour cent, leur surface terrière de 17 pour cent et leur biomasse de 16 pour cent. Afin de faciliter les comparaisons entre études, nous avons développé des équations de conversion qui relient l'abondance, le diamètre et la surface terrière des lianes à partir de mesures prises à quatre endroits sur la tige. Nous avons testé la validité de ces équations au Parc National de Lambir Hills (Malaisie): les équations ne variaient pas de manière significative entre les deux sites, suggérant qu'elles pourraient être largement applicables. Finalement, nous présentons une nouvelle équation allométrique reliant diamètre et biomasse des lianes, construite à partir de 424 lianes de cinq ensembles de données échantillonnées dans quatre pays. [source]

Quantitative Comparison of Ginsenosides and Polyacetylenes in Wild and Cultivated American Ginseng

CHEMISTRY & BIODIVERSITY, Issue 4 2010
Jing-Rong Wang
Abstract Quantitative comparison of seven ginsenosides in wild and cultivated American ginseng revealed that the Rg1/Rd ratio presented a significantly large difference between cultivated and type-I (one of the defined chemotypes) wild American ginseng, facilitating this ratio as a characteristic marker for differentiating these two groups. Similarly, the ratio (Rg1+Re)/Rd, and the ratio of protopanaxatriol (PPT)-type ginsenosides to protopanaxadiol (PPD)-type ginsenosides showed a large difference between these two groups. On the other hand, type-II wild samples were found to have high Rg1/Rb1 and Rg1/Re ratios and low panaxydol/panaxynol ratio, which is entirely different from Type-I American ginseng, but is very similar to that of Asian ginseng. This not only suggests that the chemotype should be taken into consideration properly when using these parameters for differentiating American and Asian ginseng, but also indicates that type-II wild American ginseng may have distinct pharmacological activities and therapeutic effects. [source]

Initial feasibility of a multi-station high resolution three-dimensional dark blood angiography protocol for the assessment of peripheral arterial disease

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009
Georgeta Mihai PhD
Abstract Purpose To evaluate the feasibility of a multi-station three dimensional (3D) T1-weighted turbo spin echo (TSE) dark-blood Sampling Perfection with Application optimized Contrasts using different flip angle Evolution sequence (T1w-SPACE), to assess aorta, iliac, and superficial femoral (SFA) arteries (inflow vessels) by comparing it with a multi-station contrast enhanced MR angiography (CE-MRA) with identical resolution. Materials and Methods A total of 6 volunteers and 14 peripheral arterial disease (PAD) patients were included in the study. Abdominal and thigh T1w-SPACE and lower leg time-resolved MRA (TR-MRA) with low dose contrast were followed by 3-station CE-MRA. Quantitative measurements of lumen area at 17 locations from T1w-SPACE and CE-MRA were obtained. Additionally, vessel wall areas at the same locations were obtained from the T1w-SPACE images. Results Quantitative comparison of lumen areas with T1w-SPACE and CE-MRA revealed strong correlation between the two techniques and strong inter-observer agreement for each of the two imaging methods (r > 0.9; P < 0.001). Localized vessel wall area measurements obtained in PAD patients were significantly greater compared with those obtained in normal volunteers (mean difference 43.75 ± 12.46 mm2; P < 0.001). Stenosis severity obtained from T1w-SPACE localized measurements showed significant arterial area stenosis in PAD patients. Conclusion T1w-SPACE imaging of inflow vessels is feasible, and in addition to CE-MRA has the ability to assess atherosclerotic plaque and vascular remodeling. J. Magn. Reson. Imaging 2009;30:785,793. © 2009 Wiley-Liss, Inc. [source]

Tissue Distribution, Autoradiography, and Metabolism of 4-(2,-Methoxyphenyl)-1-[2, -[N -2,-Pyridinyl)- p -[18F]Fluorobenzamido]ethyl]piperazine (p -[18F]MPPF), a New Serotonin 5-HT1A Antagonist for Positron Emission Tomography

JOURNAL OF NEUROCHEMISTRY, Issue 2 2000
An In Vivo Study in Rats
The in vivo behavior of 4-(2,-methoxyphenyl)-1-[2,-[N -(2,-pyridinyl)- p -[18F]fluorobenzamido]ethyl]-piperazine (p -[18F]MPPF), a new serotonin 5-HT1A antagonist, was studied in awake, freely moving rats. Biodistribution studies showed that the carbon-fluorine bond was stable in vivo, that this compound was able to cross the blood-brain barrier, and that a general diffusion equilibrium could account for the availability of the tracer. The great quantity of highly polar metabolites found in plasma did not contribute to the small amounts of metabolites found in hippocampus, frontal cortex, and cerebellum. Exvivo p -[18F]MPPF and in vitro 8-hydroxy-2-(di- n -[3H]propylamino)tetralin autoradiography were compared both qualitatively and quantitatively. Qualitative evaluation proved that the same brain regions were labeled and that the p -[18F]MPPF labeling is (a) in total agreement with the known distribution of 5-HT1A receptors in rats and (b) characterized by very low nonspecific binding. Quantitative comparison demonstrated that the in vivo labeling pattern obtained with p -[18F]MPPF cannot be explained by differences in regional blood flow, capillary density, or permeability. The 5-HT1A specificity of p -[18F]MPPF and binding reversibility were confirmed in vivo with displacement experiments. Thus, this compound can be used to evaluate parameters characterizing 5-HT1A binding sites in the brain. [source]

Quantitative comparison of the cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts

JOURNAL OF PERIODONTAL RESEARCH, Issue 4 2002
Noriko Maizumi
The cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts (Pel cells) was studied. Pel cells were exposed for 48 h to erythromycin (EM), clarithromycin (CAM), roxithromycin (RXM), azithromycin (AZM), josamycin (JM), midecamycin (MDM), and rokitamycin (RKM), and allowed to form colonies. The cytocidal effect of the macrolides was measured as a decrease in colony-forming efficiency and was found to increase with the concentration. To obtain a quantitative measure of the cytocidal effect, the LD50, i.e. the concentration that decreases colony-forming efficiency 50% relative to control cells, was extrapolated from the concentration-response curves. The rank of the macrolides according to their cytocidal effect (LD50) was RKM > RXM > CAM > AZM > JM > MDM , EM. RKM, RXM, CAM, AZM, and JM were at least 1.7,12.2 times more cytocidal than MDM or EM. When extrapolated from the concentration-response curves, the relative survival of the Pel cells exposed to each of the macrolides at the MIC90 concentrations for periodontopathic bacteria was estimated to be: ,,53.8% for RKM, , 92.7% for RXM, , 94.6% for CAM, , 97.1% for AZM, and , 86.2% for EM. The effect of the antibiotics on the mRNA expression of alkaline phosphatase (ALP) and type I procollagen (COL) was examined in Pel cells exposed for 48 h to RXM, CAM, AZM, and EM, which exhibited strong, moderate, and weak cytocidal activity. The constitutive levels of both ALP and COL mRNA were retained in cells exposed to RXM at ,3 ,M, CAM at ,10 ,M, and AZM or EM at ,3 ,M. The MIC90 against periodontopathic bacteria is ,4.8 ,M for RXM, 5.3 ,M for CAM, 2.7 ,M for AZM, and 21.8 ,M for EM. These results suggest that topical administration of CAM or AZM to the gingival crevice at their MIC90 concentration for periodontopathic bacteria would have little adverse effect on the growth and differentiation of the periodontal ligament. It is important to note, however, that these findings have yet to be extrapolated to in vivo conditions. [source]

Quantitative comparison of the diversity of landscapes with actual vs. potential natural vegetation

APPLIED VEGETATION SCIENCE, Issue 2 2000
Carlo Ricotta
Abstract. In the past 20 years, several metrics have been developed to quantify various aspects of landscape structure and diversity in space and time, and most have been tested on grid-based thematic maps. Once landscape patterns have been quantified, their effects on ecological functions can be explained if the expected pattern in the absence of specific processes is known. This type of expected pattern has been termed a neutral landscape model. In the landscape-ecological literature, researchers traditionally adopt random and fractal computer-generated neutral landscape models to verify the expected relationship between a given ecological process and landscape spatial heterogeneity. Conversely, little attention has been devoted to distribution patterns of potential natural vegetation (PNV) as an ecological baseline for the evaluation of pattern-process interactions at the landscape scale. As an application for demonstration, we propose a neutral model based on PNV as a possible reference for a quantitative comparison with actual vegetation (AC V) distribution. Within this context, we introduce an evenness-like index termed ,actual-to-potential entropy ratio' (HA/P = HACV/HPNV, where H is Shannon's entropy). Results show that, despite the hypothetical character of most PNV maps, the use of PNV distribution as a baseline for a quantitative comparison with ACV distribution may represent a first step towards a general model for the evaluation of the effects of disturbance on vegetation patterns and diversity. [source]

Quantitative Comparison of Ginsenosides and Polyacetylenes in Wild and Cultivated American Ginseng

High-energy X-ray diffraction using the Pixium 4700 flat-panel detector

JOURNAL OF SYNCHROTRON RADIATION, Issue 4 2009
J. E. Daniels
The Pixium 4700 detector represents a significant step forward in detector technology for high-energy X-ray diffraction. The detector design is based on digital flat-panel technology, combining an amorphous Si panel with a CsI scintillator. The detector has a useful pixel array of 1910 × 2480 pixels with a pixel size of 154,µm × 154,µm, and thus it covers an effective area of 294,mm × 379,mm. Designed for medical imaging, the detector has good efficiency at high X-ray energies. Furthermore, it is capable of acquiring sequences of images at 7.5 frames per second in full image mode, and up to 60 frames per second in binned region of interest modes. Here, the basic properties of this detector applied to high-energy X-ray diffraction are presented. Quantitative comparisons with a widespread high-energy detector, the MAR345 image plate scanner, are shown. Other properties of the Pixium 4700 detector, including a narrow point-spread function and distortion-free image, allows for the acquisition of high-quality diffraction data at high X-ray energies. In addition, high frame rates and shutterless operation open new experimental possibilities. Also provided are the necessary data for the correction of images collected using the Pixium 4700 for diffraction purposes. [source]

Quantitative comparisons of search engine results

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 11 2008
Mike Thelwall
Search engines are normally used to find information or Web sites, but Webometric investigations use them for quantitative data such as the number of pages matching a query and the international spread of those pages. For this type of application, the accuracy of the hit count estimates and range of URLs in the full results are important. Here, we compare the applications programming interfaces of Google, Yahoo!, and Live Search for 1,587 single word searches. The hit count estimates were broadly consistent but with Yahoo! and Google, reporting 5,6 times more hits than Live Search. Yahoo! tended to return slightly more matching URLs than Google, with Live Search returning significantly fewer. Yahoo!'s result URLs included a significantly wider range of domains and sites than the other two, and there was little consistency between the three engines in the number of different domains. In contrast, the three engines were reasonably consistent in the number of different top-level domains represented in the result URLs, although Yahoo! tended to return the most. In conclusion, quantitative results from the three search engines are mostly consistent but with unexpected types of inconsistency that users should be aware of. Google is recommended for hit count estimates but Yahoo! is recommended for all other Webometric purposes. [source]

A comparison of five fMRI protocols for mapping speech comprehension systems

EPILEPSIA, Issue 12 2008
Jeffrey R. Binder
Summary Aims:, Many fMRI protocols for localizing speech comprehension have been described, but there has been little quantitative comparison of these methods. We compared five such protocols in terms of areas activated, extent of activation, and lateralization. Methods:, fMRI BOLD signals were measured in 26 healthy adults during passive listening and active tasks using words and tones. Contrasts were designed to identify speech perception and semantic processing systems. Activation extent and lateralization were quantified by counting activated voxels in each hemisphere for each participant. Results:, Passive listening to words produced bilateral superior temporal activation. After controlling for prelinguistic auditory processing, only a small area in the left superior temporal sulcus responded selectively to speech. Active tasks engaged an extensive, bilateral attention, and executive processing network. Optimal results (consistent activation and strongly lateralized pattern) were obtained by contrasting an active semantic decision task with a tone decision task. There was striking similarity between the network of brain regions activated by the semantic task and the network of brain regions that showed task-induced deactivation, suggesting that semantic processing occurs during the resting state. Conclusions:, fMRI protocols for mapping speech comprehension systems differ dramatically in pattern, extent, and lateralization of activation. Brain regions involved in semantic processing were identified only when an active, nonlinguistic task was used as a baseline, supporting the notion that semantic processing occurs whenever attentional resources are not controlled. Identification of these lexical-semantic regions is particularly important for predicting language outcome in patients undergoing temporal lobe surgery. [source]

An evaluation of actual and simulated smoke properties

FIRE AND MATERIALS, Issue 2 2005
Jill Suo-Anttila
Abstract Federal regulations require that aircraft cargo compartment smoke detection systems be certified by testing their operation in flight. For safety reasons, only simulated smoke sources are permitted in these certification tests. To provide insight into smoke detection certification in cargo compartments, this research investigates the morphology, transport and optical properties of actual and simulated smoke sources. Experimental data show the morphology of the particulate in smoke from flaming fires is considerably different from simulated smoke. Although the detection of smoldering fires is important as well, only a qualitative assessment and comparison of smoldering sources was possible; therefore, efforts were concentrated on the quantitative comparison of smoke from flaming fires and smoke generators. The particulate for all three different flaming fires was solid with similar morphological properties. Simulated smoke was composed of relatively large liquid droplets, and considerably different size droplets can be produced using a single machine. Transport behavior modeling showed that both the actual and simulated smoke particulates are sufficiently small to follow the overall gas flow. However, actual smoke transport will be buoyancy driven due to the increased temperature, while the simulated smoke temperature is typically low and the release may be momentum driven. The morphology of the actual and simulated smoke were then used to calculate their optical properties. In contrast to the actual smoke from a flaming fire, which is dominated by absorption, all of the extinction for the simulated smoke is due to scattering. This difference could have an impact on detection criteria and hence the alarm time for photoelectic smoke detectors since they alarm based on the scattering properties of the smoke. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Carp (Cyprinus carpio) as a powerful invader in Australian waterways

FRESHWATER BIOLOGY, Issue 7 2004
John D. Koehn
Summary 1. The invasion of carp (Cyprinus carpio L.) in Australia illustrates how quickly an introduced fish species can spread and dominate fish communities. This species has become the most abundant large freshwater fish in south-east Australia, now distributed over more than 1 million km2. 2. Carp exhibit most of the traits predicted for a successful invasive fish species. In addition, degradation of aquatic environments in south-east Australia has given them a relative advantage over native species. 3. Derivation of relative measures of 13 species-specific attributes allowed a quantitative comparison between carp and abundant native fish species across five major Australian drainage divisions. In four of six geographical regions analysed, carp differed clearly from native species in their behaviour, resource use and population dynamics. 4. Climate matching was used to predict future range expansion of carp in Australia. All Australian surface waters appear to be climatically suitable for carp. 5. This assessment strongly reinforces the need for immediate management of carp in Australia to include targeted control of human-assisted dispersal, such as use of carp as bait by anglers, distribution to new locations by anglers and the use of the ,Koi' strain in the aquarium industry. 6. Given their historical spread, dispersal mechanisms and ecological requirements, the expansion of carp across most of the remainder of Australia is to be expected. [source]

A drought climatology for Europe

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2002
Benjamin Lloyd-Hughes
Abstract We present a high spatial resolution, multi-temporal climatology for the incidence of 20th century European drought. The climatology provides, for a given location or region, the time series of drought strength, the number, the mean duration, and the maximum duration of droughts of a given intensity, and the trend in drought incidence. The drought climatology is based on monthly standardized precipitation indices (SPIs) calculated on a 0.5° grid over the European region 35,70 °N and 35 °E,10 °W at time scales of 3, 6, 9, 12, 18, and 24 months for the period 1901,99. The standardized property facilitates the quantitative comparison of drought incidence at different locations and over different time scales. The standardization procedure (probability transformation) has been tested rigorously assuming normal, log,normal, and gamma statistics for precipitation. Near equivalence is demonstrated between the Palmer drought severity index (PDSI) and SPIs on time scales of 9 to 12 months. The mean number and duration by grid cell of extreme European drought events (SPI , ,2) on a time scale of 12 months is 6 ± 2 months and 27 ± 8 months respectively. The mean maximum drought duration is 48 ± 17 months. Trends in SPI and PDSI values indicate that the proportion of Europe experiencing extreme and/or moderate drought conditions has changed insignificantly during the 20th century. We hope the climatology will provide a useful resource for assessing both the regional vulnerability to drought and the seasonal predictability of the phenomenon. Copyright © 2002 Royal Meteorological Society. [source]

A study on the conditioning effects of natural shampoos using the scanning electron microscope*

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2001
J. Bellare
Synopsis The scanning electron microscope (SEM) was successfully used to study the effects of toiletry treatment with shampoo on the microstructure of hair. This paper describes the use of SEM for comparing the conditioning effects of herbal shampoos. Commercially available herbal shampoos are not completely natural, but contain herbal extracts in a synthetic detergent base, along with other chemical additives. Completely natural shampoos were formulated in the laboratory and their conditioning effects were evaluated by comparing with a commercially available herbal shampoo. The micrographs were studied quantitatively using ,Image Analyser Software' and the extent to which the hair scales were uplifted was measured. The results obtained from the quantitative comparison were in agreement with those obtained from other tests, such as protein loss determination. The damage caused to the hair due to sodium lauryl sulphate was visible in the micrographs. The laboratory formulations were found to be better than the commercially available product. Thus, quantitative measurements from SEM micrographs are a valuable tool to compare the conditioning effects of hair care products. Résumé Le microscope electronique balayant (SEM) est appliqué avec succès a étudier les effets de traitments hygiéniques par shampooing sur le microstucture de cheveux. L'éxposé présent signale l'emploi de SEM a comparer l'effet conditionant des shampoing naturelle (herbacé). Les shampooing herbal de commerce ne sont pas totalement naturelle mais contient extrait de herbe medicinale melangés avec une base de détergent synthetique et d'autres produits chimiques; donc shampooing totalement naturelle a eté formulés dans laboratoire et leurs effets conditionant evalués en comparant avec shampooing herbal (naturelle) de commerce. Les micrographs étaient étudiés quantitativement utilisant ,Image Analyser Software' en mesurant le degré de relèvement de écailes des cheveux. Les résultats obtenues par comparison quantitative sont en accord avec ceux obtenues par d'autres éprevues comme perte de protéine. Le dommage causé aux cheveux par SLS est visible dans les micrographs. Les formulations de laboratoire étaient trouvés meilleurs en comparant avec les produits de commerce. Donc le measure quantitative des micrographs SEM est un outil valable a comparer les effets conditionant de produits hygienique pour cheveux. [source]

Alkaline phosphatase activity in pasteurized milk: A quantitative comparison of Fluorophos and colourimetric procedures

INTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 3 2009
CLARE PAYNE
Fluorophos and colourimetric procedures for alkaline phosphatase (ALP) testing were compared using milk with raw milk additions, purified bovine ALP additions and heat treatments. Repeatability was between 0.9% and 10.1% for Fluorophos, 3.5% and 46.1% for the Aschaffenburg and Mullen (A&M) procedure and 4.4% and 8.8% for the Scharer rapid test. Linearity (,R2) using raw milk addition was 0.96 between Fluorophos and the Scharer procedure. Between the Fluorophos and the A&M procedures, R2 values were 0.98, 0.99 and 0.98 for raw milk additions, bovine ALP additions and heat treatments respectively. Fluorophos showed greater sensitivity and was both faster and simpler to perform. [source]

Influence of melt drawing on the morphology of one- and two-step processed LDPE/thermoplastic starch blends

ADVANCES IN POLYMER TECHNOLOGY, Issue 4 2003
F. J. Rodriguez-Gonzalez
Abstract In this study the morphology of LDPE/TPS blends prepared by a one-step extrusion process is compared to that obtained by reprocessing of the original blends. The influence of composition and melt drawing is examined. A novel methodology based on the form factor of the dispersed particle was used to estimate the equivalent spherical particle size of dispersed thermoplastic starch (TPS). This approach allows for the quantitative comparison of average dispersed phase particles regardless of their shape. Blends prepared in the one-step extrusion process show increased levels of anisotropy as a consequence of a combination of coalescence and particle deformation during melt drawing. Reprocessed materials demonstrate morphologies that are highly stable to a wide range of hot stretch ratio conditions. The TPS particles of reprocessed blends show no coalescence and a low degree of deformation. This phenomenon is explained by plasticizer evaporation resulting from the second processing step. The TPS is transformed from a highly deformable phase to one resembling a partially cross-linked material. These data indicate that the one-step processing of LDPE/TPS blends can be used to generate a wide range of highly elongated morphological structures. A two-step approach, analogous to typical compounding and shaping operations and involving controlled glycerol removal in the second step can be used to prepare a wide range of highly stable, more isotropic, dispersed particle morphologies. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 297,305, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10057 [source]

Comparison of TCA and ICA techniques in fMRI data processing

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2004
Xia Zhao MS
Abstract Purpose To make a quantitative comparison of temporal cluster analysis (TCA) and independent component analysis (ICA) techniques in detecting brain activation by using simulated data and in vivo event-related functional MRI (fMRI) experiments. Materials and Methods A single-slice MRI image was replicated 150 times to simulate an fMRI time series. An event-related brain activation pattern with five different levels of intensity and Gaussian noise was superimposed on these images. Maximum contrast-to-noise ratio (CNR) of the signal change ranged from 1.0 to 2.0 by 0.25 increments. In vivo visual stimulation fMRI experiments were performed on a 1.9 T magnet. Six human volunteers participated in this study. All imaging data were analyzed using both TCA and ICA methods. Results Both simulated and in vivo data have shown that no statistically significant difference exists in the activation areas detected by both ICA and TCA techniques when CNR of fMRI signal is larger than 1.75. Conclusion TCA and ICA techniques are comparable in generating functional brain maps in event-related fMRI experiments. Although ICA has richer features in exploring the spatial and temporal information of the functional images, the TCA method has advantages in its computational efficiency, repeatability, and readiness to average data from group subjects. J. Magn. Reson. Imaging 2004;19:397,402. © 2004 Wiley-Liss, Inc. [source]

Viral loads of herpes simplex virus in clinical samples,A 5-year retrospective analysis,

JOURNAL OF MEDICAL VIROLOGY, Issue 11 2010
Julian W. Tang
Abstract Viral loads of herpes simplex virus (HSV) are not monitored usually for the effective clinical management of HSV-related diseases. However, recently, there has been more interest about the typical HSV levels in clinical specimens, and how such data may improve understanding of the behavior of this virus in such clinical presentations, particularly in immunocompromised patients, where more prolonged therapy using higher doses of antiviral drugs may be required. Using an in-house quantitative HSV-1/HSV-2 polymerase chain reaction assay, an observational, retrospective 5-year analysis of diagnostic, quantitative HSV-1 and HSV-2 DNA levels was conducted. The results (all in median log10 DNA copies/ml), including perhaps the first quantitative comparison of cerebrospinal fluid (CSF) HSV viral loads, were as follows: CSF: HSV-1, 3.40 (range 2.30,8.98) versus HSV-2, 3.60 (range 2.31,6.86) (P,=,0.559); plasma: HSV-1, 3.20 (range 2.23,5.51) versus HSV-2, 3.20 (range 3.18,3.41) (P,=,0.905); genital swabs: HSV-1, 6.79 (range 2.28,8.48) versus HSV-2, 6.97 (range 3.40,9.66) (P,=,0.810); oral swabs: HSV-1, 7.28 (range 2.46,10.04) versus HSV-2, 5.62 (range 4.60,6.63) (P,=,0.529). Note that with the samples usually collected for HSV testing (i.e., CSF, plasma, oral, and genital swabs) there was no significant difference in the viral loads between HSV-1 and HSV-2 types, nor between immunocompetent and immunocompromised patients for each of these different HSV types. Indeed, even between immunocompromised patients with similar diseases, for these samples, the HSV loads were found to vary considerably. These findings may therefore limit the usefulness of monitoring HSV loads in everyday clinical practice. J. Med. Virol. 82:1911,1916, 2010. © 2010 Wiley-Liss, Inc. [source]

Less systemic cytokine response in patients following microendoscopic versus open lumbar discectomy

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2005
Tsung-Jen Huang
Abstract The magnitude of the tissue damage from surgery impacts the trauma response. This response is proportional to the severity of surgical stress. Systemic cytokines are recognized as markers of postoperative tissue trauma. Microendoscopic discectomy (MED) recently has become popular for treating lumbar disc herniations, and is associated with favorable clinical outcomes compared with open discectomy (OD). This study postulates that MED is a less traumatic procedure, and therefore has a lower surgical stress response compared to OD. In this study, a quantitative comparison of the overall effects of surgical trauma resulting from MED and OD was performed through analyzing patient systemic cytokines response. From April, 2002 to June, 2003, 22 consecutive patients who had symptomatic lumbar disc herniations were prospectively randomized to undergo either intracanalicular MED (N = 10) or OD (N = 12). In this study, the Vertebroscope System (Zeppelin, Pullach, Germany) was used to perform the endoscopic discectomy procedure in all MED patients. Serum levels of tumor necrosis factor-, (TNF-,), Interleukin-1, (IL-1,), Interleukin-6 (IL-6), and Interleukin-8 (IL-8) were measured before surgery and at 1, 2, 4, 8 and 24h after surgery using an enzyme-linked immunosorbent assay. Serum C-reactive protein (CRP) was measured at the same time interval. The results showed the MED patients had shorter postoperative hospital stay (mean, 3.57 ± 0.98 vs. 5.92 ± 2.39 days, p = 0.025) and less intraoperative blood loss (mean. 87.5 ± 69.4 vs. 190 ± 115 ml, p = 0.042). The operating length, including the set-up time, was longer in the MED group (mean, 109 ± 35.9 vs. 72.1 ± 17.8 min, p = 0.01). The mean size of skin incision made for the MED patients was 1.86 ± 0.13cm (range 1.7,2.0cm); and 6.3 ± 0.98 cm for the OD patients (range 5.5,8cm), p = 0.001. The patients' pain severity of the involved limbs on 10-point Visual Analog Scale before operation in MED group was 7.5 ± 0.3 (range 6,9) and 8 ± 0.2 (range 7,9) in OD group, p = 0.17; and after surgery, 1.5 ± 0.2 (range 1,2) in MED group and 1.4 ± 0.1 (range 1,3) in OD group, p = 0.91. CRP levels peaked at 24h in both groups, and OD patients displayed a significantly greater postoperative rise in serum CRP (mean, 27.78 ± 15.02 vs. 13.84 ± 6.25mg/l, p = 0.026). Concentrations of TNF-,, IL-1,, and IL-8 were detected only sporadically. Serum IL-6 increased less significantly following MED than after OD. In the MED group, IL-6 level peaked 8 h after surgery, with the response statistically less than in the open group (mean, 6.27 ± 5.96 vs. 17.18 ± 11.60pg/ml, p = 0.025). A statistically significant correlation was identified between IL-6 and CRP values (r = 0.79). Using the modified MacNab criteria, the clinical outcomes were 90% satisfactory (9/10) in MED patients and 91.6% satisfactory (11/12) in OD patients at a mean 18.9 months (range 10,25) follow-up. Based on the current data, surgical trauma, as reflected by systemic IL-6 and CRP response, was significantly less following MED than following OD. The difference in the systemic cytokine response may support that the MED procedure is less traumatic. Moreover, our MED patients had achieved satisfactory clinical outcomes as the OD patients at a mean 18.9 months follow-up after surgery. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]

A quantitative comparison of the ontogeny of two closely-related Upper Devonian phacopid trilobites

LETHAIA, Issue 2 2005
CATHERINE CRÔNIER
The best insight into the development of Devonian phacopids has been obtained from Trimerocephalus lelievrei Crônier & Feist, 1997, a Famennian phacopine from Morocco, where changes in size and shape have been quantified. In this study, a morphometric approach has been used: (1) to retrodeform and then establish patterns of morphological variation in a well preserved but tectonically deformed assemblage belonging to another phacopine species Weyerites ensae (Richter & Richter, 1926), a Famennian phacopine from Thuringia, and (2) to establish patterns of developmental and evolutionary changes within two closely related species: Weyerites ensae and Trimerocephalus lelievrei. The method of retrodeformation using a set of discrete points presumed to be homologous on all studied individuals, has demonstrated that the next analyses are possible on the retrodeformed material as compared to the undeformed material. Morphometric analysis based on outline analysis has permitted demonstration of progressive shape change in agreement with ontogenetic ordination and a comparison of changes in size and shape in Weyerites ensae. The main changes in shape appear to occur in the meraspid period, whereas increase in size takes place mainly in the holaspid period. This pattern, already reported for Trimerocephalus lelievrei, can be generalized for phacopine trilobites from the Late Devonian. Moreover, the comparison of the two ontogenetic trajectories has shown that most of the differences are related to ,structural' changes, probably linked to a relative pre- post-displacement. The results suggest that ecological adaptation may be studied by examining the changes in development that occur within species through time and space. [source]

Mode crystallography of distorted structures

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2010
J. M. Perez-Mato
The description of displacive distorted structures in terms of symmetry-adapted modes is reviewed. A specific parameterization of the symmetry-mode decomposition of these pseudosymmetric structures defined on the setting of the experimental space group is proposed. This approach closely follows crystallographic conventions and permits a straightforward transformation between symmetry-mode and conventional descriptions of the structures. Multiple examples are presented showing the insight provided by the symmetry-mode approach. The methodology is shown at work, illustrating its various possibilities for improving the characterization of distorted structures, for example: detection of hidden structural correlations, identification of fundamental and marginal degrees of freedom, reduction of the effective number of atomic positional parameters, quantitative comparison of structures with the same or different space group, detection of false refinement minima, systematic characterization of thermal behavior, rationalization of phase diagrams and various symmetries in families of compounds etc. The close relation of the symmetry-mode description with the superspace formalism applied to commensurate superstructures is also discussed. Finally, the application of this methodology in the field of ab initio or first-principles calculations is outlined. At present, there are several freely available user-friendly computer tools for performing automatic symmetry-mode analyses. The use of these programs does not require a deep knowledge of group theory and can be applied either a posteriori to analyze a given distorted structure or a priori to parameterize the structure to be determined. It is hoped that this article will encourage the use of these tools. All the examples presented here have been worked out using the program AMPLIMODES [Orobengoa et al. (2009). J. Appl. Cryst.42, 820,833]. [source]

Research Review: The relationship between childhood violence exposure and juvenile antisocial behavior: a meta-analytic review

THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 7 2009
Helen W. Wilson
Background:, The connection between childhood violence exposure and antisocial behavior in adolescence has received much attention and has important implications for understanding and preventing criminal behavior. However, there are a limited number of well-designed prospective studies that can suggest a causal relationship, and little is known about the magnitude of the relationship. Methods:, This meta-analysis provides a quantitative comparison of 18 studies (N = 18,245) assessing the relationship between childhood (before age 12) violence exposure and adolescent antisocial behavior. An overall effect size (Cohen's d) was calculated for each study, an average for the 18 studies, and averages for subsets of analyses within studies. Results:, Results indicated a small effect from prospective studies (d = .31) and a large effect from cross-sectional studies (d = .88). The effect for victimization (d = .61) was larger than for witnessing violence (d = .15). Conclusions:, Effect size varied across studies employing different methodologies, populations, and conceptualizations of violence exposure and antisocial behavior. These findings do not support a simple, direct link from early violence exposure to antisocial behavior but suggest that many factors influence this relationship. [source]

Tiling among stereotyped dendritic branches in an identified Drosophila motoneuron,,

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 12 2010
F. Vonhoff
Abstract Different types of neurons can be distinguished by the specific targeting locations and branching patterns of their dendrites, which form the blueprint for wiring the brain. Unraveling which specific signals control different aspects of dendritic architecture, such as branching and elongation, pruning and cessation of growth, territory formation, tiling, and self-avoidance requires a quantitative comparison in control and genetically manipulated neurons. The highly conserved shapes of individually identified Drosophila neurons make them well suited for the analysis of dendritic architecture principles. However, to date it remains unclear how tightly dendritic architecture principles of identified central neurons are regulated. This study uses quantitative reconstructions of dendritic architecture of an identified Drosophila flight motoneuron (MN5) with a complex dendritic tree, comprising more than 4,000 dendritic branches and 6 mm total length. MN5 contains a fixed number of 23 dendritic subtrees, which tile into distinct, nonoverlapping volumes of the diffuse motor neuropil. Across-animal comparison and quantitative analysis suggest that tiling of the different dendritic subtrees of the same neuron is caused by competitive and repulsive interactions among subtrees, perhaps allowing different dendritic compartments to be connected to different circuit elements. We also show that dendritic architecture is similar among different wildtype and GAL4 driver fly lines. Metric and topological dendritic architecture features are sufficiently constant to allow for studies of the underlying control mechanisms by genetic manipulations. Dendritic territory and certain topological measures, such as tree compactness, are most constant, suggesting that these reflect the intrinsic molecular identity of the neuron. J. Comp. Neurol. 518:2169,2185, 2010. © 2010 Wiley-Liss, Inc. [source]

Structural basis for the phase transitions of Cs2HgCl4

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001
Bagautdin Bagautdinov
The a0× b0× 2c0 twofold superstructure of dicaesium mercury tetrachloride, Cs2HgCl4, at T = 120,K has been determined by single-crystal X-ray diffraction using synchrotron radiation. Lattice parameters were found as a = 9.7105,(2), b = 7.4691 (1), c = 26.8992 (4) Å, and , = 90.368,(1)° with the supercell space group P21/c. Refinements on 1828 observed unique reflections converged to R = 0.053 (wR = 0.057) using anisotropic temperature factors for all atoms. This phase is the stable phase of Cs2HgCl4 below 163,K. A quantitative comparison is made of the distortions of the 2c0 superstructure with the undistorted phase that is stable at room temperature, and with the 3c0 and 5a0 superstructures that are stable at temperatures between 163,K and room temperature. The principal difference between the 2c0 superstructure and all other phases of Cs2HgCl4 is that the Cs cations are displaced away from the centers of their coordination polyhedra in the 2c0 superstructure. The structural basis for the driving force of the series of phase transitions in this compound is found in the variations of the environments of Cs atoms and in the variations of the distortions of the HgCl4 tetrahedra. [source]

Factors underpinning the responsiveness and higher levels of virus resistance realised in potato genotypes carrying virus-specific R genes

ANNALS OF APPLIED BIOLOGY, Issue 2 2010
A.L. Vuorinen
Responses to Potato virus A (PVA, genus Potyvirus) segregate to three phenotypic groups in a diploid cross between Solanum tuberosum subsp. andigena and a highly interspecific potato hybrid. The aim of this study was to compare gene expression between the progeny genotypes which react with hypersensitive response (HR) to PVA, allow PVA accumulation in inoculated leaves but restrict PVA infection to the inoculated leaf by blocking systemic movement [non-necrotic resistance (nnr)], or are susceptible (S) and systemically infected with PVA. Expression levels of ca 10 000 genes were compared using probes arranged in a microarray format, and real-time RT-PCR was applied for quantitative comparison of the expression of selected defense-related genes (DRGs). Results showed that a few DRGs were autoactivated in HR genotypes at an early stage of plant growth in the absence of PVA infection, which was not observed in the two other phenotypic groups (nnr and S). More detailed studies on the DRGs encoding a beta-1,3-glucanase, a chitinase and a basic PR-1b protein showed that autoactivation of the genes was not evident in vitro and up to 2 weeks of growth in soil in a controlled growth cabinet but was apparent 2 weeks later. Hence, autoinduction of these DRGs in the HR genotypes could be associated with growth stage, environmental factors or both. Furthermore, a number of other DRGs were induced in the inoculated leaves of HR genotypes as a response to infection with PVA, which was not observed in nnr and S genotypes. These results provide some novel information about factors underpinning the higher levels of virus resistance realised in potato genotypes carrying virus-specific R genes and suggest that part of the resistance is attributable to additional ,minor' genes functioning simultaneously, hence adding to the overall responsiveness and level of resistance against infection. These results also imply that some genotypes might be more responsive to chemical induction of pathogen and pest resistance, which could be considered in screening of progenies in plant-breeding programs. [source]

Quantitative comparison of the diversity of landscapes with actual vs. potential natural vegetation

Integrated strategies for assessment of metabolite exposure in humans during drug development: analytical challenges and clinical development considerations

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2009
Mingshe Zhu
Abstract Monitoring the exposure of a drug and its metabolites in humans and preclinical species during drug development is required to ensure that the safety of drug-related components in humans are adequately assessed in the standard toxicology studies. Recently published FDA guidance on metabolites in safety testing (MIST) has generated broad discussion from various perspectives. Most of the opinions and experiences shared among the scientific community are scientifically sound and practical. There are various approaches to assess the metabolite exposure margin between toxicology species and humans: either by direct or indirect comparison or by qualitative or quantitative comparison. The choice of when and how to pursuit metabolite assessment is based on the overall development strategy of the compound. Therefore, it is important to understand the utility and limitations of analytical instruments in order to apply an appropriate analytical tool to address specific questions posed at different stages of drug development. The urgency of metabolite monitoring depends on the intrinsic nature of the compound, therapeutic intent and objective of the clinical development. The strategy for assessing metabolite exposure in humans should be a holistic approach considering clinical situations and cumulative knowledge of the metabolism of the drug in order to appropriately address metabolite safety in humans. A one-size-fits-all approach is rarely the best use of resources. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Filtering and Counting of Extended Connectivity Fingerprint Features Maximizes Compound Recall and the Structural Diversity of Hits

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2009
Ye Hu
Extended connectivity fingerprints produce variable numbers of structural features for molecules and quantitative comparison of feature ensembles is typically carried out as a measure of molecular similarity. As an alternative way to utilize the information content of extended connectivity fingerprint features, we have introduced a compound class-directed feature filtering technique. In combination with a simple feature counting protocol, feature filtering significantly improves the performance of extended connectivity fingerprint similarity searching compared with state-of-the-art fingerprint search methods. Subsets of extended connectivity fingerprint features that are unique to active compounds are found to be responsible for high compound recall. Moreover, feature filtering and counting is shown to result in significantly higher scaffold hopping potential than data fusion or fingerprint averaging methods. Extended connectivity fingerprint feature filtering and counting represents one of the simplest similarity search methods introduced to date, yet it produces top compound recall and maximizes the scaffold diversity of hits, which is a longstanding goal of similarity searching. [source]

Influence of the Charge State on the Structures and Interactions of Vancomycin Antibiotics with Cell-Wall Analogue Peptides: Experimental and Theoretical Studies

CHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2009
Zhibo Yang Dr.
Abstract Charge matters! The charge state significantly influences the conformation and the binding energy between vancomycin antibiotic and bacterial cell-wall analogue peptides (see figure). Surface-induced dissociation (SID) studies provide a quantitative comparison between the stabilities of different charge states of the complex. In this study we examined the effect of the charge state on the energetics and dynamics of dissociation of the noncovalent complex between the vancomycin and the cell-wall peptide analogue N,,N, -diacetyl- L -Lys- D -Ala- D -Ala (V,Ac2LKdAdA). The binding energies between the vancomycin and the peptide were obtained from the RRKM (Rice, Ramsperger, Kassel, Marcus) modeling of the time- and energy-resolved surface-induced dissociation (SID) experiments. Our results demonstrate that the stability of the complex towards fragmentation increases in the order: doubly protonated[source]