975 resultados para "manner"


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Although LH is essential for survival and function of the corpus luteum (CL) in higher primates, luteolysis occurs during nonfertile cycles without a discernible decrease in circulating LH levels. Using genome-wide expression analysis, several experiments were performed to examine the processes of luteolysis and rescue of luteal function in monkeys. Induced luteolysis with GnRH receptor antagonist (Cetrorelix) resulted in differential regulation of 3949 genes, whereas replacement with exogenous LH (Cetrorelix plus LH) led to regulation of 4434 genes (1563 down-regulation and 2871 up-regulation). A model system for prostaglandin (PG) F-2 alpha-induced luteolysis in the monkey was standardized and demonstrated that PGF(2 alpha) regulated expression of 2290 genes in the CL. Analysis of the LH-regulated luteal transcriptome revealed that 120 genes were regulated in an antagonistic fashion by PGF(2 alpha). Based on the microarray data, 25 genes were selected for validation by real-time RT-PCR analysis, and expression of these genes was also examined in the CL throughout the luteal phase and from monkeys treated with human chorionic gonadotropin (hCG) to mimic early pregnancy. The results indicated changes in expression of genes favorable to PGF(2 alpha) action during the late to very late luteal phase, and expressions of many of these genes were regulated in an opposite manner by exogenous hCG treatment. Collectively, the findings suggest that curtailment of expression of downstream LH-target genes possibly through PGF(2 alpha) action on the CL is among the mechanisms underlying cross talk between the luteotropic and luteolytic signaling pathways that result in the cessation of luteal function, but hCG is likely to abrogate the PGF(2 alpha)-responsive gene expression changes resulting in luteal rescue crucial for the maintenance of early pregnancy. (Endocrinology 150: 1473-1484, 2009)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Antibodies to LH/chorionic gonadotrophin receptor (LH/CG-R; molecular weight 67 000), isolated in a homogenous state (established by SDS-PAGE and ligand blotting) from sheep luteal membrane using human CG (hCG)-Sepharose affinity chromatography, were raised in three adult male rabbits (R-I, R-II and R-III). Each of the rabbits received 20-30 mu g oi the purified receptor in Freund's complete adjuvant at a time. Primary immunization was followed by booster injection at intervals. Production of receptor antibodies was monitored by (1) determining the dilution of the serum (IgG fraction) that could specifically bind 50% of I-125-LH/CG-R added and (2) analysing sera for any chance in testosterone levels. Following primary immunization and the first booster, all three rabbits exhibited a 2.5- to 6.0-fold increase in serum testosterone over basal levels and this effect was spread over a period of time (similar to 40 days) coinciding with the rise and fall of receptor antibodies. The maximal antibody titre (ED(50)) produced at this time ranged from 1:350 to 1:100 to below detectable limits for R-I, R-II and R-III respectively. Subsequent immunizations followed by the second booster resulted in a substantial increase in antibody titre (ED(50) of 1:5000) in R-I, but this was not accompanied by any change in serum testosterone over preimmune levels, suggesting that with the progress of immunization the character of the antibody produced had also changed. Two pools of antisera from R-I collected 10 days following the booster (at day 70 (bleed I) and day 290 (bleed II)) were used in further experiments. IgG isolated from bleed I but not from bleed II antiserum showed a dose-dependent stimulation of testosterone production by mouse Leydig cells in vitro, thus confirming the in vivo hormone-mimicking activity antibodies generated during the early immunization phase. The IgG fractions from both bleeds were, however, capable of inhibiting (1) I-125-hCG binding to crude sheep luteal membrane (EC(50) of 1:70 and 1:350 for bleed I and II antisera respectively) and (2) ovine LH-stimulated testosterone production by mouse Leydig cells in vitro, indicating the presence oi antagonistic antibodies irrespective of the period of time during which the rabbits were immunized. The: fact that bleed I-stimulated testosterone production could be inhibited in a dose-dependent manner by the addition of IgG from bleed II to the mouse Leydig cell in vitro assay system showed that the agonistic activity is intrinsic to the bleed I antibody. The receptor antibody (bleed II) was also capable of blocking LH action in vivo, as rabbits passively (for 24 h with LH/CG-R antiserum) as well as actively (for 130 days) immunized against LH/CG-R failed to respond to a bolus injection of LH (50 mu g). At no time, however, was the serum testosterone reduced below the basal level. This study clearly shows that, unlike with LH antibody, attempts to achieve an LH deficiency effect in vivo by resorting to immunization with hole LH receptor is difficult, as receptor antibodies exhibit both hormone-mimicking (agonistic) as well as hormone-blocking (antagonistic) activities.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We present two six-parameter families of anisotropic Gaussian Schell-model beams that propagate in a shape-invariant manner, with the intensity distribution continuously twisting about the beam axis. The two families differ in the sense or helicity of this beam twist. The propagation characteristics of these shape-invariant beams are studied, and the restrictions on the beam parameters that arise from the optical uncertainty principle are brought out. Shape invariance is traced to a fundamental dynamical symmetry that underlies these beams. This symmetry is the product of spatial rotation and fractional Fourier transformation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Lasers are very efficient in heating localized regions and hence they find a wide application in surface treatment processes. The surface of a material can be selectively modified to give superior wear and corrosion resistance. In laser surface-melting and welding problems, the high temperature gradient prevailing in the free surface induces a surface-tension gradient which is the dominant driving force for convection (known as thermo-capillary or Marangoni convection). It has been reported that the surface-tension driven convection plays a dominant role in determining the melt pool shape. In most of the earlier works on laser-melting and related problems, the finite difference method (FDM) has been used to solve the Navier Stokes equations [1]. Since the Reynolds number is quite high in these cases, upwinding has been used. Though upwinding gives physically realistic solutions even on a coarse grid, the results are inaccurate. McLay and Carey have solved the thermo-capillary flow in welding problems by an implicit finite element method [2]. They used the conventional Galerkin finite element method (FEM) which requires that the pressure be interpolated by one order lower than velocity (mixed interpolation). This restricts the choice of elements to certain higher order elements which need numerical integration for evaluation of element matrices. The implicit algorithm yields a system of nonlinear, unsymmetric equations which are not positive definite. Computations would be possible only with large mainframe computers.Sluzalec [3] has modeled the pulsed laser-melting problem by an explicit method (FEM). He has used the six-node triangular element with mixed interpolation. Since he has considered the buoyancy induced flow only, the velocity values are small. In the present work, an equal order explicit FEM is used to compute the thermo-capillary flow in the laser surface-melting problem. As this method permits equal order interpolation, there is no restriction in the choice of elements. Even linear elements such as the three-node triangular elements can be used. As the governing equations are solved in a sequential manner, the computer memory requirement is less. The finite element formulation is discussed in this paper along with typical numerical results.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The application of radical-mediated cyclizations and annulations in organic synthesis has grown in importance steadily over the years to reach the present status where they are now routinely used in the strategy-level planning.2 The presence of a quaternary carbon atom is frequently encountered in terpenoid natural products, and it often creates a synthetic challenge when two or more quaternary carbon atoms are present in a contiguous manner.3 Even though creation of a quaternary carbon atom by employing a tertiary radical is very facile, creation of a quaternary carbon atom (or a spiro carbon atom) via radical addition onto a fully substituted olefinic carbon atom is not that common but of synthetic importance. For example, the primary radical derived from the bromide 1 failed to cyclize to generate the two vicinal quaternary carbon atoms and resulted in only the reduced product 2.4 The tricyclic carbon framework tricyclo[6.2.1.01,5]undecane (3) is present in a number of sesquiterpenoids e.g. zizzanes, prelacinanes, etc.5

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose In the mainstream relationship management literature, critical appraisal of the relationship paradigm in an international setting is virtually non-existent. The extant literature reveals a gap in terms of linking relationship management theories with international management. Furthermore, little research attention has been paid to synthesise the existing theories in a cohesive manner towards developing a theoretical paradigm in the interface of the importer-supplier relationship dyad. Thus, the purpose of this paper is to strengthen the theoretical grounds of relationship marketing in an international setting in an importer-exporter relationship context. Design/methodology/approach The paper follows a comprehensive review approach and applies the fundamental theory of trust and commitment to identify the relational factors. More precisely, the paper identifies and applies other relevant theories such as internationalisation process theory, resource-based theory of the firm, dependence theory and transaction cost theory in developing an innovative theoretical paradigm. Findings Based on the integration of extant theories, this paper proposes a new direction in the theoretical realm of the trust and commitment building process within an importer and supplier relationship management paradigm. The research concludes that trust and commitment are the focal factors within the international relational paradigm. Research limitations/implications The proposed research direction suggests an emerging framework integrating mainstream theoretical variables of trust and commitment in importer and foreign-supplier context. This novel framework has the potential for use in further research. Originality/value This paper advances a grounded theoretical exploration within an international management domain in the context of importers and foreign-suppliers.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Recognizing similarities and deriving relationships among protein molecules is a fundamental requirement in present-day biology. Similarities can be present at various levels which can be detected through comparison of protein sequences or their structural folds. In some cases similarities obscure at these levels could be present merely in the substructures at their binding sites. Inferring functional similarities between protein molecules by comparing their binding sites is still largely exploratory and not as yet a routine protocol. One of the main reasons for this is the limitation in the choice of appropriate analytical tools that can compare binding sites with high sensitivity. To benefit from the enormous amount of structural data that is being rapidly accumulated, it is essential to have high throughput tools that enable large scale binding site comparison. Results: Here we present a new algorithm PocketMatch for comparison of binding sites in a frame invariant manner. Each binding site is represented by 90 lists of sorted distances capturing shape and chemical nature of the site. The sorted arrays are then aligned using an incremental alignment method and scored to obtain PMScores for pairs of sites. A comprehensive sensitivity analysis and an extensive validation of the algorithm have been carried out. A comparison with other site matching algorithms is also presented. Perturbation studies where the geometry of a given site was retained but the residue types were changed randomly, indicated that chance similarities were virtually non-existent. Our analysis also demonstrates that shape information alone is insufficient to discriminate between diverse binding sites, unless combined with chemical nature of amino acids. Conclusion: A new algorithm has been developed to compare binding sites in accurate, efficient and high-throughput manner. Though the representation used is conceptually simplistic, we demonstrate that along with the new alignment strategy used, it is sufficient to enable binding comparison with high sensitivity. Novel methodology has also been presented for validating the algorithm for accuracy and sensitivity with respect to geometry and chemical nature of the site. The method is also fast and takes about 1/250(th) second for one comparison on a single processor. A parallel version on BlueGene has also been implemented.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In order to explore the anticancer effect associated with the thiazolidinone framework, several 2-(5-((5-(4-chlorophenyl)furan-2-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)acetic acid derivatives 5(a-1) were synthesized. Variation in the functional group at C-terminal of the thiazolidinone led to set of compounds bearing amide moiety. Their chemical structures were confirmed by H-1 NMR, IR and Mass Spectra analysis. These thiazolidinone compounds containing furan moiety exhibits moderate to strong antiproliferative activity in a cell cycle stage-dependent and dose dependent manner in two different human leukemia cell lines. The importance of the electron donating groups on thiazolidinone moiety was confirmed by MTT and Trypan blue assays and it was concluded that the 4th position of the substituted aryl ring plays a dominant role for its anticancer property. Among the synthesized compounds, 5e and 5f have shown potent anticancer activity on both the cell lines tested. To rationalize the role of electron donating group in the induction of cytotoxicity we have chosen two molecules (5e and 5k) having different electron donating group at different positions. LDH assay, Flow cytometric analysis and DNA fragmentation suggest that 5e is more cytotoxic and able to induce the apoptosis. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Enumeration of adhered cells of Thiobacillus ferrooxidans on sulphide minerals through protein assay poses problems due to interference from dissolved mineral constituents. The manner in which sulphide minerals such as pyrite, chalcopyrite, sphalerite, arsenopyrite and pyrrhotite interfere with bacterial protein estimation is demonstrated. Such interferences can be minimised either through dilution or addition of H2O2 to the filtrate after hot alkaline digestion of the biotreated mineral samples.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Wireless adhoc networks transmit information from a source to a destination via multiple hops in order to save energy and, thus, increase the lifetime of battery-operated nodes. The energy savings can be especially significant in cooperative transmission schemes, where several nodes cooperate during one hop to forward the information to the next node along a route to the destination. Finding the best multi-hop transmission policy in such a network which determines nodes that are involved in each hop, is a very important problem, but also a very difficult one especially when the physical wireless channel behavior is to be accounted for and exploited. We model the above optimization problem for randomly fading channels as a decentralized control problem - the channel observations available at each node define the information structure, while the control policy is defined by the power and phase of the signal transmitted by each node. In particular, we consider the problem of computing an energy-optimal cooperative transmission scheme in a wireless network for two different channel fading models: (i) slow fading channels, where the channel gains of the links remain the same for a large number of transmissions, and (ii) fast fading channels, where the channel gains of the links change quickly from one transmission to another. For slow fading, we consider a factored class of policies (corresponding to local cooperation between nodes), and show that the computation of an optimal policy in this class is equivalent to a shortest path computation on an induced graph, whose edge costs can be computed in a decentralized manner using only locally available channel state information (CSI). For fast fading, both CSI acquisition and data transmission consume energy. Hence, we need to jointly optimize over both these; we cast this optimization problem as a large stochastic optimization problem. We then jointly optimize over a set of CSI functions of the local channel states, and a c- - orresponding factored class of control poli.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Urban planning policies in Australia presuppose apartments as the new dominant housing type, but much of what the market has delivered is criticised as over-development, and as being generic, poorly-designed, environmentally unsustainable and unaffordable. Policy responses to this problem typically focus on planning regulation and construction costs as the primary issues needing to be addressed in order to increase the supply of quality, affordable apartment housing. In contrast, this paper uses Ball’s (1983) ‘structures of provision’ approach to outline the key processes informing apartment development and identifies a substantial gap in critical understanding of how apartments are developed in Australia. This reveals economic problems not typically considered by policymakers. Using mainstream economic analysis to review the market itself, the authors found high search costs, demand risk, problems with exchange, and lack of competition present key barriers to achieving greater affordability and limit the extent to which ‘speculative’ developers can respond to the preferences of would be owner-occupiers of apartments. The existing development model, which is reliant on capturing uplift in site value, suits investors seeking rental yields in the first instance and capital gains in the second instance, and actively encourages housing price inflation. This is exacerbated by lack of density restrictions, such as have existed in inner Melbourne for many years, which permits greater yields on redevelopment sites. The price of land in the vicinity of such redevelopment sites is pushed up as landholders' expectation of future yield is raised. All too frequently existing redevelopment sites go back onto the market as vendors seek to capture the uplift in site value and exit the project in a risk free manner...

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Assembly intermediates of icosahedral viruses are usually transient and are difficult to identify. In the present investigation, site-specific and deletion mutants of the coat protein gene of physalis mottle tymovirus (PhMV) were used to delineate the role of specific amino acid residues in the assembly of the virus and to identify intermediates in this process. N-terminal 30, 34, 35 and 39 amino acid deletion and single C-terminal (N188) deletion mutant proteins of PhMV were expressed in Escherichia coli. Site-specific mutants H69A, C75A, W96A, D144N, D144N-T151A, K143E and N188A were also constructed and expressed. The mutant protein lacking 30 amino acid residues from the N terminus self-assembled to T = 3 particles in vivo while deletions of 34, 35 and 39 amino acid residues resulted in the mutant proteins that were insoluble. Interestingly, the coat protein (pR PhCP) expressed using pRSET B vector with an additional 41 amino acid residues at the N terminus also assembled into T = 3 particles that were more compact and had a smaller diameter. These results demonstrate that the amino-terminal segment is flexible and either the deletion or addition of amino acid residues at the N terminus does not affect T = 3 capsid assembly, in contrast, the deletion of even a single residue from the C terminus (PhN188 Delta 1) resulted in capsids that were unstable. These capsids disassembled to a discrete intermediate with a sedimentation coefficent of 19.4 S. However, the replacement of C-terminal asparagine 188 by alanine led to the formation of stable capsids. The C75A and D144N mutant proteins also assembled into capsids that were as stable as the pR PhCP, suggesting that C75A and D144 are not crucial for the T = 3 capsid assembly. pR PhW96A and pR PhD144N-T151A mutant proteins failed to form capsids and were present as heterogeneous aggregates. Interestingly, the pR PhK143E mutant protein behaved in a manner similar to the C-terminal deletion protein in forming unstable capsids. The intermediate with an s value of 19.4 S was the major assembly product of pR PhH69A mutant protein and could correspond to a 30mer. It is possible that the assembly or disassembly is arrested at a similar stage in pR PhN188 Delta 1, pR PhH69A and pR PhK143E mutant proteins.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In the present investigation, two nozzle configurations are used for spray deposition, convergent nozzle (nozzle-A), and convergent nozzle with 2 mm parallel portion attached at its end (nozzle-C) without changing the exit area. First, the conditions for subambient aspiration pressure, i.e., pressure at the tip of the melt delivery tube, are established by varying the protrusion length of the melt delivery tube at different applied gas pressures for both of the nozzles. Using these conditions, spray deposits in a reproducible manner are successfully obtained for 7075 Al alloy. The effect of applied gas pressure, flight distance, and nozzle configuration on various characteristics of spray deposition, viz., yield, melt flow rate, and gas-to-metal ratio, is examined. The over-spray powder is also characterized with respect to powder size distribution, shape, and microstructure. Some of the results are explained with the help of numerical analysis presented in an earlier article.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objective To examine the impact of efforts to improve nutrition on the Anangu Pitjantjatjara Yankunytjatjara (APY) Lands from 1986, especially in Mai Wiru stores. Methods Literature was searched in a systematic manner. In 2012, the store-turnover method was used to quantify dietary intake of the five APY communities that have a Mai Wiru (good food) store. Results were compared with those available from 1986. Prices of a standard market basket of basic foods, implementation of nutrition policy requirements and healthy food checklists were also assessed in all seven APY community stores from 2008 and compared with available data from 1986. Results Despite concerted efforts and achievements decreasing intake of sugar and increasing the availability and affordability of healthy foods, particularly fruit and vegetables, and consequent improvements in some nutrient indicators, the overall effect has been a decrease in diet quality as indicated primarily by the increased supply and proportion of energy intake from discretionary foods, particularly sugar-sweetened beverages, convenience meals and take-away foods. Conclusions The study findings reinforce the notion that, in the absence of supportive regulation and market intervention, adequate and sustained resources are required to improve nutrition and prevent diet-related chronic disease on the APY Lands. Implications This study also provides insights into food supply/security issues affecting other remote Aboriginal communities and wider Australia.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A number of studies in yeast have shown that DNA topoisomerase TI is essential for chromosome condensation and disjunction during mitosis at the metaphase/anaphase transition and meiosis I. Accordingly, kinetic and mechanistic studies have implied a role for topoisomerase rr in chromosome disjunction. As a step toward understanding the nature and role of topoisomerase II in a mammalian germline in vivo, we have purified topoisomerase II from rat testis to homogeneity and ascertained several of its catalytic activities in conjunction with that of the purified enzyme from liver. The purified enzymes appeared to be monomers under denaturing conditions; however, they differed in their relative molecular mass. Topoisomerase II from testis and liver have apparent molecular masses of 150 +/- 10 kDa and 160 +/- 10 kDa, respectively. The native molecular mass of testis topoisomerase II as assayed by immunoblot analysis of cell-foe extracts, prepared in the presence of SDS and a number of protease inhibitors, corroborated with the size of the purified enzyme. Both enzymes are able to promote decatenation and relax supercoiled DNA substrates in an ATP and Mg2+-dependent manner. However, quantitative comparison of catalytic properties of topoisomerase II from testis with that of the enzyme from liver displayed significant differences in their efficiencies. Optimal pH values for testis enzyme are 6.5 to 8.5 while they are 6 to 7.5 for the liver enzyme. Intriguingly, the relaxation activity of liver topoisomerase II was inhibited by potassium glutamate at 1 M, whereas testis enzyme required about half its concentration. These findings argue that topoisomerase II from rat testis is structurally distinct from that of its somatic form and the functional differences between the two enzymes parallels with the physiological environment that is unique to these two tissues.