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Slight Variations (slight + variation)
Selected AbstractsNew scaling relations in cluster radio haloes and the re-acceleration modelMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007R. Cassano ABSTRACT In this paper we derive new expected scaling relations for clusters with giant radio haloes in the framework of the re-acceleration scenario in a simplified, but physically motivated, form, namely: radio power (PR) versus size of the radio emitting region (RH), and PR versus total cluster mass (MH) contained in the emitting region and cluster velocity dispersion (,H) in this region. We search for these correlations by analysing the most recent radio and X-ray data available in the literature for a well-known sample of clusters with giant radio haloes. In particular we find a good correlation between PR and RH and a very tight ,geometrical' scaling between MH and RH. From these correlations PR is also expected to scale with MH and ,H and this is confirmed by our analysis. We show that all the observed trends can be well reconciled with expectations in the case of a slight variation of the mean magnetic field strength in the radio halo volume with MH. A byproduct correlation between RH and ,H is also found, and can be further tested by optical studies. In addition, we find that observationally RH scales non-linearly with the virial radius of the host cluster, and this immediately means that the fraction of the cluster volume which is radio emitting increases with cluster mass and thus that the non-thermal component in clusters is not self-similar. [source] Histologically low-grade dedifferentiated liposarcoma of the retroperitoneumPATHOLOGY INTERNATIONAL, Issue 5 2001Masaharu Fukunaga A low-grade dedifferentiated liposarcoma in the retroperitoneum of a 52-year-old woman is described. The excised specimens contained six nodules of lipoma-like well-differentiated liposarcoma and a nodule of dedifferentiated liposarcoma. The latter was composed predominantly of loosely arranged, benign-appearing spindle cells and fat cells. A small number of cells with irregularly shaped nuclei were scattered. There were no mitotic figures. The fat cells showed slight variation of size and shape, and a few multivacuolated lipoblasts were found. The spindle cell areas occupied approximately 60% of the tumor. The stroma was somewhat fibrous and myxoid and no dense collagenous matrix was found. The stroma vascularity was not prominent. Immunohistochemically, the spindle cells were positive for vimentin but negative for S-100 protein, desmin, muscle actin, and , -smooth muscle actin. Follow up for 5 months showed no evidence of recurrence or metastasis. The tumor, in which the benign-appearing spindle cell component was predominant, was considered to be a low-grade dedifferentiated liposarcoma. Close and long-term follow up is required. In retroperitoneal lipoma-like well-differentiated liposarcomas, spindle cell components like the present tumor, which represent dedifferentiation, should not be overlooked. [source] A COMPARISON OF THE CHEMICAL AND ENGINEERING CHARACTERISTICS OF ANCIENT ROMAN HYDRAULIC CONCRETE WITH A MODERN REPRODUCTION OF VITRUVIAN HYDRAULIC CONCRETE*ARCHAEOMETRY, Issue 4 2008E. GOTTI The authors have completed structural and compositional analysis of Roman hydraulic concrete using large cores taken from a variety of maritime structures. In 2005 an 8 m3 block of hydraulic, pozzolanic concrete was built in the sea at Brindisi (Italy), applying the materials and procedures specified by the Roman architect Vitruvius. Cores were taken at 6 months and 12 months after construction and subjected to the same analyses as the first-century bc cores from pilae associated with the Villa of the Domitii Ahenobarbi at Santa Liberata. Results show that a slight variation on the Vitruvian formula yields results closest to the Roman material, and that substantial curing requires 12 months. [source] The actin gene family: Function follows isoform,CYTOSKELETON, Issue 10 2010Benjamin J. Perrin Although actin is often thought of as a single protein, in mammals it actually consists of six different isoforms encoded by separate genes. Each isoform is remarkably similar to every other isoform, with only slight variations in amino acid sequence. Nevertheless, recent work indicates that actin isoforms carry out unique cellular functions. Here, we review evidence drawn from localization studies, mouse models, and biochemical characterization to suggest a model for how in vivo mixing of actin isoforms may influence cytoskeletal function in cells. © 2010 Wiley-Liss, Inc. [source] Is my antibody-staining specific?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2008How to deal with pitfalls of immunohistochemistry Abstract Immunohistochemistry is a sensitive and versatile method widely used to investigate the cyto- and chemoarchitecture of the brain. It is based on the high affinity and selectivity of antibodies for a single epitope. However, it is now recognized that the specificity of antibodies needs to be tested in control experiments to avoid false-positive results due to non-specific binding to tissue components or recognition of epitopes shared by several molecules. This ,Technical Spotlight' discusses other pitfalls, which are often overlooked, although they can strongly influence the outcome of immunohistochemical experiments. It also recapitulates the minimal set of information that should be provided in scientific publications to allow proper evaluation and replication of immunohistochemical experiments. In particular, tissue fixation and processing can have a strong impact on antigenicity by producing conformational changes to the epitopes, limiting their accessibility (epitope masking) or generating high non-specific background. These effects are illustrated for an immunoperoxidase staining experiment with three antibodies differing in susceptibility to fixation, using tissue from mice processed under identical conditions, except for slight variations in tissue fixation. In these examples, specific immunostaining can be abolished depending on fixation strength, or detected only after prolonged postfixation. As a consequence, antibody characterization in immunohistochemistry should include their susceptibility towards fixation and determination of the optimal conditions for their use. [source] Engineering the properties of a cold active enzyme through rational redesign of the active siteFEBS JOURNAL, Issue 19 2001Iason Tsigos ,In an effort to explore the effects of local flexibility on the cold adaptation of enzymes, we designed point mutations aiming to modify side-chain flexibility at the active site of the psychrophilic alkaline phosphatase from the Antarctic strain TAB5. The mutagenesis targets were residues Trp260 and Ala219 of the catalytic site and His135 of the Mg2+ binding site. The replacement of Trp260 by Lys in mutant W260K, resulted in an enzyme less active than the wild-type in the temperature range 5,25 °C. The additional replacement of Ala219 by Asn in the double mutant W260K/A219N, resulted in a drastic increase in the energy of activation, which was reflected in a considerably decreased activity at temperatures of 5,15 °C and a significantly increased activity at 20,25 °C. Further substitution of His135 by Asp in the triple mutant W260K/A219N/H135D restored a low energy of activation. In addition, the His135,Asp replacement in mutants H135D and W260K/A219N/H135D resulted in considerable stabilization. These results suggest that the psychrophilic character of mutants can be established or masked by very slight variations of the wild-type sequence, which may affect active site flexibility through changes in various conformational constraints. [source] Material Solubility-Photovoltaic Performance Relationship in the Design of Novel Fullerene Derivatives for Bulk Heterojunction Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Pavel A. Troshin Abstract The preparation of 27 different derivatives of C60 and C70 fullerenes possessing various aryl (heteroaryl) and/or alkyl groups that are appended to the fullerene cage via a cyclopropane moiety and their use in bulk heterojunction polymer solar cells is reported. It is shown that even slight variations in the molecular structure of a compound can cause a significant change in its physical properties, in particular its solubility in organic solvents. Furthermore, the solubility of a fullerene derivative strongly affects the morphology of its composite with poly(3-hexylthiophene), which is commonly used as active material in bulk heterojunction organic solar cells. As a consequence, the solar cell parameters strongly depend on the structure and the properties of the fullerene-based material. The power conversion efficiencies for solar cells comprising these fullerene derivatives range from negligibly low (0.02%) to considerably high (4.1%) values. The analysis of extensive sets of experimental data reveals a general dependence of all solar cell parameters on the solubility of the fullerene derivative used as acceptor component in the photoactive layer of an organic solar cell. It is concluded that the best material combinations are those where donor and acceptor components are of similar and sufficiently high solubility in the solvent used for the deposition of the active layer. [source] EFFECT OF GLYCEROL ON PHYSICAL PROPERTIES OF CASSAVA STARCH FILMSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2010P. BERGO ABSTRACT In this work, the effect of glycerol on the physical properties of edible films were identified by X-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared (FTIR) and microwave spectroscopy. According to XRD diffractograms, films with 0 and 15% glycerol displayed an amorphous character, and a tendency to semicrystallization, for films with 30% and 45% glycerol. From DSC thermograms, the glass transition (Tg) of the films decreased with glycerol content. However, two Tgs were observed for samples with 30% and 45% glycerol, due to a phase separation. The intensity and positions of the peaks in FTIR fingerprint region presented slight variations due to new interactions arising between glycerol and biopolymer. Microwave measurements were sensitive to moisture content in the films, due to hydrophilic nature of the glycerol. The effect of plasticizer plays, then, an important rule on the physical and functional properties of these films, for applications in food technology. PRACTICAL APPLICATIONS Edible and/or biodegradable films are thin materials used mainly in food recovering, food packaging and other applications, in substitution of the films obtained by synthetic ways. In view of these applications, these films must satisfy some of the exigencies in order to increase the food shelf-life, or in other words, they must be flexible, transparent, resistant to some gases such as oxygen, as well as resistant to water vapor. The addition of plasticizers alters the functional properties of the films. Thus, the physical characterization of these films becomes fundamental in order to increase their potential use in industry. [source] Investigation of impinging-jet crystallization with a calcium oxalate model systemAICHE JOURNAL, Issue 9 2003Jean M. Hacherl An impinging-jet crystallizer was investigated in this work to assess its operational sensitivity and reproducibility for the production of small, monodisperse crystals using calcium oxalate, a model system capable of forming multiple hydrates. The impinging-jet mixer provides rapid mixing of the reactant solutions through the impingement of two narrow reactant streams at high velocity. Impinging jet linear velocity and postjetting conditions were studied, with the jet operated in nonsubmerged mode. Hydrate form and crystal-size distribution (CSD) were determined using optical microscopy and image analysis techniques. The impinging jet consistently produced small, monodisperse crystals. However, at a high level of supersaturation, slight variations in the CSD were observed for apparently identical conditions, suggesting a degree of sensitivity in the system that could lead to difficulty in its application. An apparent trend between impinging-jet linear velocity and crystal size and number was observed, with more small crystals produced at higher linear velocity. [source] Evaluation of cottonseed meal derived from genetically modified cotton as feed ingredients for channel catfish, Ictalurus punctatusAQUACULTURE NUTRITION, Issue 6 2008M.H. LI Abstract Three laboratory experiments were conducted to assess nutritional quality of cottonseed meals from genetically modified (GM) cotton crops, Roundup Ready® Flex, Bollgard® × Roundup Ready, Bollgard II® × Roundup Ready, and Bollgard II × Roundup Ready Flex for channel catfish, Ictalurus punctatus using Good Laboratory Practices. Growth, feed efficiency, survival, and fillet composition of catfish fed diets containing 20% cottonseed meal from these cotton products were compared with that of catfish fed diets containing cottonseed meals from the near-isogenic, non-GM control and non-GM commercial varieties. Juvenile catfish (mean weights of 4.1, 5.0, and 0.6 g per fish for Experiments 1, 2, and 3, respectively) were stocked in each of 80-L aquaria and fed experimental diets for 8 weeks. Although there were slight variations in proximate composition, amino acids, and gossypol concentrations, the GM cottonseed meals were not significantly different from the conventional control and the reference cottonseed meals. Weight gain, feed conversion, survival, and fillet composition of catfish fed GM cottonseed meals appeared similar to that of either the control or the commercial cottonseed meals. Results from the present study demonstrate that these GM cottonseed meals are nutritionally equivalent to conventional non-GM cotton varieties when fed to catfish at 20% of the diet. [source] | |||||||||||||