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31572. Quantification of Intra-Abdominal Fat During Controlled Weight Reduction: Assessment Using the Water-Suppressed Breath-Hold MRI Technique

Creator:
Tintěra, J., Harantová, P., Suchánek, P., Dvořáková, A., Adamová, A., Hájek, M., and Poledne, R.
Type:
article, model:article, and TEXT
Subject:
Intra-abdominal adipose tissue, MRI, and Weight loss
Language:
English
Description:
A group of 14 healthy female subjects was studied using MRI during 2 months of life-style intervention. A series of 21 water-suppressed images was used to determine the intra-abdominal fat volume before and after the controlled loss of weight. The average weight decrease was 8.2 %, but the average relative loss of visceral fat was 20.3 %, whereas subcutaneous fat decreased by 13.4 %. A small but significant increase of insulin sensitivity (decrease in fasting insulin and blood glucose) was observed, but no changes in lipoprotein parameters were demonstrated. There was a significant negative correlation (r=–0.633, p=0.028) between the relative abdominal fat decrease and the initial amount of subcutaneous fat.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

31574. Quantifying and interpreting functional diversity of natural communities

Creator:
Lepš, Jan, Bello, Francesco de, Lavorel, Sandra, and Berman, Sandra
Type:
article and TEXT
Subject:
biodiversity index, functional trait, grasslands, intraspecific and interspecific diversity, PCA, Rao index, resource use efficiency, sampling effect, SLA, and stable isotope
Language:
English
Description:
Quantifying the functional diversity in ecological communities is very promising for both studying the response of diversity to environmental gradients and the effects of diversity on ecosystem functioning (i.e. in “biodiversity experiments”). In our view, the Rao coefficient is a good candidate for an efficient functional diversity index. It is, in fact, a generalization of the Simpson’s index of diversity and it can be used with various measures of dissimilarity between species (both those based on a single trait and those based on several traits). However, when intending to quantify the functional diversity, we have to make various methodological decisions such as how many and which traits to use, how to weight them, how to combine traits that are measured at different scales and how to quantify the species’ relative abundances in a community. Here we discuss these issues with examples from real plant communities and argue that diversity within a single trait is often the most ecologically relevant information. When using indices based on many traits, we plead for careful a priori selection of ecologically relevant traits, although other options are also feasible. When combining many traits, often with different scales, methods considering the extent of species overlap in trait space can be applied for both the qualitative and quantitative traits. Another possibility proposed here is to decompose the variability of a trait in a community according to the relative effect of among- and within-species differentiation (with the latter not considered by current indices of functional diversity), in a way analogical to decomposition of Sum of squares in ANOVA. Further, we show why the functional diversity is more tightly related to species diversity (measured by Simpson index) when biomass is used as a measure of population abundance, in comparison with frequency. Finally, the general expectation is that functional diversity can be a better predictor of ecosystem functioning than the number of species or the number of functional groups. However, we demonstrate that some of the expectations might be overrated – in particular, the “sampling effect“ in biodiversity experiments is not avoided when functional diversity is used as a predictor.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/

31575. Quantifying aphid predation rates of generalist predators in the field

Creator:
Harwood, James D. and Obrycki, Joh J.
Type:
article, model:article, and TEXT
Subject:
Gut-content analysis, polyclonal antisera, monoclonal antibodies, PCR, biological control, and generalist
Language:
English
Description:
The community of predators within agroecosystems has the potential to restrict aphid populations, especially early in the season before exponential increases in density and prior to the arrival of specialist natural enemies. Although direct observations of predation, laboratory feeding trials and manipulative field studies have been used to estimate levels of biological control exerted by different species (or potentially negative interactions between them), it is often difficult to extrapolate results to naturally occurring interactions in the field. Over 100 investigations have utilized gut-content analysis to estimate aphid predation rates by predators. Throughout the last century, gut dissection, which enables the visual identification of aphid body parts, has been used in over 50% of studies although accurate identification and quantification of predation is difficult. Other techniques have included radio-labelling of prey, dissection of faecal samples, electrophoresis, stable isotope analysis and use of polyclonal antisera. In recent studies of invertebrate predation, monoclonal antibodies have been the most frequently applied technique but advances in molecular biology have enabled the detection of species-specific DNA sequences. The use of these applications to quantify predation by aphidophagous predators will be reviewed, with emphasis on potential sources of error and difficulties of quantitative interpretation. Despite the considerable focus currently directed towards molecular approaches, antibody-based techniques are likely to remain an important tool for studying predation rates of pests in the field, especially when antibodies have already been developed. However, the study of multiple predation events within complex generalist predator food webs is only likely through the detection of species-specific DNA sequences using molecular techniques.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31576. Quantifying colour difference in animals with variable patterning

Creator:
Dračková, Tereza, Smolinský, Radovan, Hiadlovská, Zuzana, Dolinay, Matej, and Martínková, Natália
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
colouration, Reptilia, image analysis, colour pattern, RGB, and CIELAB
Language:
English
Description:
Colour pattern influences behaviour and affects survival of organisms through perception of light reflectance. Spectrophotometric methods used to study colour optimise precision and accuracy of reflectance across wavelengths, while multiband photographs are generally used to assess the complexity of colour patterns. Using standardised photographs of sand lizards (Lacerta agilis), we compare how colours characterised using point measurements (using the photographs, but simulating spectrophotometry) on the skin differ from colours estimated by clustering pixels in the photograph of the lizard's body. By taking photographs in the laboratory and in the field, the experimental design included two 2-way comparisons. We compare point vs. colour clustering characterisation and influence of illumination in the laboratory and in the field. We found that point measurements adequately represented the dominant colour of the lizard. Where colour patterning influenced measurement geometry, image analysis outperformed point measurement with respect to stability between technical replicates on the same animal. The greater colour variation derived from point measurements increased further under controlled laboratory illumination. Both methods revealed lateral colour asymmetry in sand lizards, i.e. that colours subtly differed between left and right flank. We conclude that studies assessing the impact of colour on animal ecology and behaviour should utilise hyperspectral imaging, followed by image analysis that encompasses the whole colour pattern.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31577. Quantifying impact of droughts on barley yield in North Dakota, USA using Multiple Linear Regression and Artificial Neural Network

Creator:
Odabas, Mehmet Serhat , Leelaruban , Navaratnam, Simsek, Halis, and Padmanabhan , G.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Barley yield, multiple linear regression, artificial neural network, and drought impact
Language:
English
Description:
This research investigated the effect of different drought conditions on Barley (Hordeum vulgare L.) yield in North Dakota, USA, using Multiple Linear Regression (MLR) and Artificial Neural Network (ANN) methods. Though MLR method is widely used, the ANN method has not been used in the past to investigate the effect of droughts on barley yields to the best of authors’ knowledge. It is found from this study that the ANN model performs better than MLR in estimating barley yield. In this paper, the ANN is proposed as a viable alternative method or in combination with MLR to investigate the impact of droughts on crop yields.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31578. Quantitative analysis of cerebrospinal fluid brain derived neurotrophic factor in the patients with multiple sclerosis

Creator:
Mashayekhi, Farhad, Salehi, Zivar, and Jamalzadeh, Hamid Reza
Format:
braille, text, and regular print
Type:
model:article, article, Text, and TEXT
Subject:
dospělí, mozkový neurotrofický faktor--mok mozkomíšní, ženské pohlaví, lidé, mužské pohlaví, and roztroušená skleróza--mok mozkomíšní
Language:
English
Description:
Multiple sclerosis (MS) is the most common cause of nontraumatic neurological disability in Europe and North America. Growth factor expression could participate in the repair process of the demyelinating disease. Among growth factors, brain derived neurotrophic factors (BDNF) has been demonstrated to play an important role in neuronal and axonal survival. In the central nervous system (CNS ), neurons are the main source of BDNF. Another potential source are activated astrocytes, which are present in inflamed areas in the CNS as shown in MS. In this study, total protein concentration (TPC) and BDNF levels in the cerebrospinal fluid (CS F) samples from the patients with MS (n = 48) and control subjects (n = 53) were measured using a Bio-Rad protein assay and enzyme linked immunosorbent assay (ELISA). No significant change in the CS F TPC of patients with MS was seen as compared to normal CS F. The presence of BDNF in the CS F samples was shown by Western blot. Using ELISA , it was shown that the level of BDNF in the MS CS F is higher than in normal CS F. It is concluded that BDNF is a constant component of human CS F. Moreover, it could be implicated in the pathophysiology of MS., Farhad Mashayekhi, Zivar Salehi, Hamid Reza Jamalzadeh, and Literatura 27
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31580. Quantitative analysis of the influence of temperature and confining pressure on brittleness of granite: a review

Creator:
Zhao, Fei, Sun, Qiang, and Zhang , Weiqiang
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
granite, temperature, confining pressure, and brittleness
Language:
English
Description:
In order to quantitatively study the influence of temperature and confining pressure on brittle plasticity of granite, this paper reviews previous studies regarding quantitative calculation methods for the brittle-plastic behaviors of rocks and their mechanical characteristics under high temperatures and confining pressures. Combining the experimental results for temperatures and confining pressures with theoretical calculations of brittleness and plasticity allowed quantitative calculations and evaluations for the brittleness and plasticity of granite to be obtained. The main conclusions are as follows. (1) High temperatures lead to a transformation of granite from brittle failure to plastic failure. Comparing six conventional empirical equations from the literature, the B3 and B6 can more accurately describe the relationship between the brittleness and temperature of granite. (2) When the confining pressure σ3 is less than 20 MPa, the internal pore structure and fractures of granite are re-compacted and reduced, which gradually increases its brittleness. With the increasing confining pressure, the pore structure changes again after exceeding 20 MPa. This initiates new cracks, which ultimately leads to a decrease of the granite brittleness. (3) The abrupt temperature for the brittle-plastic transformation of granite is approximately 800 °C, and the brittle-plastic transformation of granite is mainly affected by temperature and not the confining pressure.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

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