855 resultados para Competitive Exclusion Principle


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The cultivation of dessert apples has to meet the consumer's increasing demand for high fruit quality and a sustainable mostly residue-free production while ensuring a competitive agricultural productivity. It is therefore of great interest to know the impact of different cultivation methods on the fruit quality and the chemical composition, respectively. Previous studies have demonstrated the feasibility of High Resolution Magic Angle Spinning (HR-MAS) NMR spectroscopy directly performed on apple tissue as analytical tool for metabonomic studies. In this study, HR-MAS NMR spectroscopy is applied to apple tissue to analyze the metabolic profiles of apples grown under 3 different cultivation methods. Golden Delicious apples were grown applying organic (Bio), integrated (IP) and low-input (LI) plant protection strategies. A total of 70 1H HR-MAS NMR spectra were analyzed by means of principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Apples derived from Bio-production could be well separated from the two other cultivation methods applying both, PCA and PLS-DA. Apples obtained from integrated (IP) and low-input (LI) production discriminated when taking the third PLS-component into account. The identified chemical composition and the compounds responsible for the separation, i.e. the PLS-loadings, are discussed. The results are compared with fruit quality parameters assessed by conventional methods. The present study demonstrates the potential of HR-MAS NMR spectroscopy of fruit tissue as analytical tool for finding markers for specific fruit production conditions like the cultivation method.

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A statistical mechanics view leads to the conclusion that polar molecules allowed to populate a degree of freedom for orientational disorder in a condensed phase thermalize into a bi-polar state featuring zero net polarity. In cases of orientational disorder polar order of condensed molecular matter can only exist in corresponding sectors of opposite average polarities. Channel type inclusion compounds, single component molecular crystals, solid solutions, optically anomalous crystals, inorganic ionic crystals, biomimetic crystals and biological tissues investigated by scanning pyroelectric and phase sensitive second harmonic generation microscopy all showed domains of opposite polarities in their final grown state. For reported polar molecular crystal structures it is assumed that kinetic hindrance along one direction of the polar axis is preventing the formation of a bi-polar state, thus allowing for a kinetically controlled mono-domain state. In this review we summarize theoretical and experimental findings leading to far reaching conclusions on the polar state of solid molecular matter. “… no stationary state … of a system has an electrical dipole moment.” P. W. Anderson, Science, 1972, 177, 393.

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The match time spent on court in racquet sports can be perceived as dependent on the effort an athlete is willing to exert in a competition. Achievement motivation is defined as the effort a person spends on a difficult task with the completion of which she wants to meet a personal standard of excellence, wants to improve herself, or outperform others (McClelland, Atkinson, Clark, & Lowell, 1953). Fifty-two professionals of three racquet sports (tennis, table tennis, and badminton) filled in a questionnaire on their explicit achievement motive, a scale on general life stress, and a measure of the implicit achievement motive. Results indicate that the implicit but not the explicit achievement motive was able to predict the athletes' time spent on court (effort). Additionally the general life stress scale was negatively related to time spent on court. Findings are in line with theoretical assumptions that actual behavior is linked to the implicit achievement motive and that higher levels of general life stress lead to impaired performance in sports.

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Recurrent airway obstruction is one of the most common airway diseases affecting mature horses. Increased bronchoalveolar mucus, neutrophil accumulation in airways, and airway obstruction are the main features of this disease. Mucociliary clearance is a key component of pulmonary defense mechanisms. Cilia are the motile part of this system and a complex linear array of dynein motors is responsible for their motility by moving along the microtubules in the axonemes of cilia and flagella. We previously detected a QTL for RAO on ECA 13 in a half-sib family of European Warmblood horses. The gene encoding DNAH3 is located in the peak of the detected QTL and encodes a dynein subunit. Therefore, we analysed this gene as a positional and functional candidate gene for RAO. In a mutation analysis of all 62 exons we detected 53 new polymorphisms including 7 non-synonymous variants. We performed an association study using 38 polymorphisms in a cohort of 422 animals. However, after correction for multiple testing we did not detect a significant association of any of these polymorphisms with RAO (P>0.05). Therefore, it seems unlikely that variants at the DNAH3 gene are responsible for the RAO QTL in European Warmblood horses.

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Children and adolescents with hearing impairments are at risk of being excluded from activities with hearing peers. Moral emotion attributions may represent important indicators for children’s identification with the moral norm not to exclude peers based on disability. Against this background, we investigated how 10-, 12- and 15-year-olds (N = 215) feel and judge about social exclusion of peers with hearing impairments. Emotion attributions and moral judgements were assessed using four different hypothetical scenarios about the exclusion of peers with hearing impairments (school vs. leisure time, group vs. dyad). Moreover, children’s and adolescents’ inclusive behaviour was assessed by a peer nomination procedure. Results revealed that moral emotion attributions differed as a function of exclusion context and grade. Moreover, participants with inclusive behaviour attributed moral emotions more often than participants with less inclusive behaviour. Implications of the results for moral education are discussed.

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Rapid pollen tube growth places unique demands on energy production and biosynthetic capacity. The aim of this work is to understand how primary metabolism meets the demands of such rapid growth. Aerobically grown pollen produce ethanol in large quantities. The ethanolic fermentation pathway consists of two committed enzymes: pyruvate decarboxylase ( PDC) and alcohol dehydrogenase ( ADH). Because adh mutations do not affect male gametophyte function, the obvious question is why pollen synthesize an abundant enzyme if they could do just as well without. Using transposon tagging in Petunia hybrida, we isolated a null mutant in pollen- specific Pdc2. Growth of the mutant pollen tubes through the style is reduced, and the mutant allele shows reduced transmission through the male, when in competition with wild- type pollen. We propose that not ADH but rather PDC is the critical enzyme in a novel, pollen- specific pathway. This pathway serves to bypass pyruvate dehydrogenase enzymes and thereby maintain biosynthetic capacity and energy production under the unique conditions prevailing during pollen - pistil interaction.

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Competitive Market Segmentation Abstract In a two-firm model where each firm sells a high-quality and a low-quality version of a product, customers differ with respect to their brand preferences and their attitudes towards quality. We show that the standard result of quality-independent markups crucially depends on the assumption that the customers' valuation of quality is identical across firms. Once we relax this assumption, competition across qualities leads to second-degree price discrimination. We find that markups on low-quality products are higher if consuming a low-quality product involves a firm-specific disutility. Likewise, markups on high-quality products are higher if consuming a high-quality product creates a firm-specific surplus. Selection upon Wage Posting Abstract We discuss a model of a job market where firms announce salaries. Thereupon, they decide through the evaluation of a productivity test whether to hire applicants. Candidates for a job are locked in once they have applied at a given employer. Hence, such a market exhibits a specific form of the bargain-then-ripoff principle. With a single firm, the outcome is efficient. Under competition, what might be called "positive selection" leads to market failure. Thus our model provides a rationale for very small employment probabilities in some sectors. Exclusivity Clauses: Enhancing Competition, Raising Prices Abstract In a setting where retailers and suppliers compete for each other by offering binding contracts, exclusivity clauses serve as a competitive device. As a result of these clauses, firms addressed by contracts only accept the most favorable deal. Thus the contract-issuing parties have to squeeze their final customers and transfer the surplus within the vertical supply chain. We elaborate to what extent the resulting allocation depends on the sequence of play and discuss the implications of a ban on exclusivity clauses.

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Ovine foot rot caused by Dichelobacter nodosus is affecting sheep worldwide. The current diagnostic methods are difficult and cumbersome. Here, we present a competitive real-time PCR based on allelic discrimination of the protease genes aprV2 and aprB2. This method allows direct detection and differentiation of virulent and benign D. nodosus from interdigital skin swabs in a single test. Clinically affected sheep harbored high loads of only virulent strains, whereas healthy sheep had lower loads of predominantly benign strains.

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Positive-stranded viruses synthesize their RNA in membrane-bound organelles, but it is not clear how this benefits the virus or the host. For coronaviruses, these organelles take the form of double-membrane vesicles (DMVs) interconnected by a convoluted membrane network. We used electron microscopy to identify murine coronaviruses with mutations in nsp3 and nsp14 that replicated normally while producing only half the normal amount of DMVs under low-temperature growth conditions. Viruses with mutations in nsp5 and nsp16 produced small DMVs but also replicated normally. Quantitative reverse transcriptase PCR (RT-PCR) confirmed that the most strongly affected of these, the nsp3 mutant, produced more viral RNA than wild-type virus. Competitive growth assays were carried out in both continuous and primary cells to better understand the contribution of DMVs to viral fitness. Surprisingly, several viruses that produced fewer or smaller DMVs showed a higher fitness than wild-type virus at the reduced temperature, suggesting that larger and more numerous DMVs do not necessarily confer a competitive advantage in primary or continuous cell culture. For the first time, this directly demonstrates that replication and organelle formation may be, at least in part, studied separately during infection with positive-stranded RNA virus. IMPORTANCE The viruses that cause severe acute respiratory syndrome (SARS), poliomyelitis, and hepatitis C all replicate in double-membrane vesicles (DMVs). The big question about DMVs is why they exist in the first place. In this study, we looked at thousands of infected cells and identified two coronavirus mutants that made half as many organelles as normal and two others that made typical numbers but smaller organelles. Despite differences in DMV size and number, all four mutants replicated as efficiently as wild-type virus. To better understand the relative importance of replicative organelles, we carried out competitive fitness experiments. None of these viruses was found to be significantly less fit than wild-type, and two were actually fitter in tests in two kinds of cells. This suggests that viruses have evolved to have tremendous plasticity in the ability to form membrane-associated replication complexes and that large and numerous DMVs are not exclusively associated with efficient coronavirus replication.

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Most cases of Duchenne muscular dystrophy are caused by dystrophin gene mutations that disrupt the mRNA reading frame. Artificial exclusion (skipping) of a single exon would often restore the reading frame, giving rise to a shorter, but still functional dystrophin protein. Here, we analyzed the ability of antisense U7 small nuclear (sn)RNA derivatives to alter dystrophin pre-mRNA splicing. As a proof of principle, we first targeted the splice sites flanking exon 23 of dystrophin pre-mRNA in the wild-type muscle cell line C2C12 and showed precise exon 23 skipping. The same strategy was then successfully adapted to dystrophic immortalized mdx muscle cells where exon-23-skipped dystrophin mRNA rescued dystrophin protein synthesis. Moreover, we observed a stimulation of antisense U7 snRNA expression by the murine muscle creatine kinase enhancer. These results demonstrate that alteration of dystrophin pre-mRNA splicing could correct dystrophin gene mutations by expression of specific U7 snRNA constructs.

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BACKGROUND Due to the implementation of the diagnosis-related groups (DRG) system, the competitive pressure on German hospitals increased. In this context it has been shown that acute pain management offers economic benefits for hospitals. The aim of this study was to analyze the impact of the competitive situation, the ownership and the economic resources required on structures and processes for acute pain management. MATERIAL AND METHODS A standardized questionnaire on structures and processes of acute pain management was mailed to the 885 directors of German departments of anesthesiology listed as members of the German Society of Anesthesiology and Intensive Care Medicine (DGAI, Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin). RESULTS For most hospitals a strong regional competition existed; however, this parameter affected neither the implementation of structures nor the recommended treatment processes for pain therapy. In contrast, a clear preference for hospitals in private ownership to use the benchmarking tool QUIPS (quality improvement in postoperative pain therapy) was found. These hospitals also presented information on coping with the management of pain in the corporate clinic mission statement more often and published information about the quality of acute pain management in the quality reports more frequently. No differences were found between hospitals with different forms of ownership in the implementation of acute pain services, quality circles, expert standard pain management and the implementation of recommended processes. Hospitals with a higher case mix index (CMI) had a certified acute pain management more often. The corporate mission statement of these hospitals also contained information on how to cope with pain, presentation of the quality of pain management in the quality report, implementation of quality circles and the implementation of the expert standard pain management more frequently. There were no differences in the frequency of using the benchmarking tool QUIPS or the implementation of recommended treatment processes with respect to the CMI. CONCLUSION In this survey no effect of the competitive situation of hospitals on acute pain management could be demonstrated. Private ownership and a higher CMI were more often associated with structures of acute pain management which were publicly accessible in terms of hospital marketing.