3,972 research outputs found

    What determines auditory similarity? The effect of stimulus group and methodology.

    Get PDF
    Two experiments on the internal representation of auditory stimuli compared the pairwise and grouping methodologies as means of deriving similarity judgements. A total of 45 undergraduate students participated in each experiment, judging the similarity of short auditory stimuli, using one of the methodologies. The experiments support and extend Bonebright's (1996) findings, using a further 60 stimuli. Results from both methodologies highlight the importance of category information and acoustic features, such as root mean square (RMS) power and pitch, in similarity judgements. Results showed that the grouping task is a viable alternative to the pairwise task with N > 20 sounds whilst highlighting subtle differences, such as cluster tightness, between the different task results. The grouping task is more likely to yield category information as underlying similarity judgements

    The effective mass of two--dimensional 3He

    Full text link
    We use structural information from diffusion Monte Carlo calculations for two--dimensional 3He to calculate the effective mass. Static effective interactions are constructed from the density-- and spin structure functions using sumrules. We find that both spin-- and density-- fluctuations contribute about equally to the effective mass. Our results show, in agreement with recent experiments, a flattening of the single--particle self--energy with increasing density, which eventually leads to a divergent effective mass.Comment: 4 pages, accepted in PR

    Segmental Duplications: a Possible Mechanism of Hominid Uplift Through MicroRNA Diversification

    Get PDF
    MicroRNAs (miRNA) are ~21 nucleotide-long gene silencers. Segmental duplications (SD) are among the driving forces in acquiring new genes. Both miRNA and SD are believed to have played a significant role in evolution, particularly in the divergence of humans (Homo sapiens) from the chimpanzee (Pan troglodytes). This study determines the distribution of miRNAs in humans and in chimpanzees, and presents a hypothesis on its significance in the occurrence of segmental duplications. MiRNA sequences from miRBASE were subjected to BLAT and BLAST to determine if miRNAs are located in SD regions or not. Homology between miRNAs was determined with ClustalW. BLAST was then used to determine whether the non-homologous human miRNA are homologous to any other part of the chimpanzee genome. We found that all 695 human miRNAs are found exclusively in SD regions, and that 67 are de novo miRNAs. Thirteen are homologues of chimpanzee miRNA, and 11 were possibly derived from non-miRNA regions in chimp. Of these, 6 were located in SD regions of the chimpanzee genome. Results indicate that miRNA evolution occurs within regions of segmental duplication and suggest that the presence of miRNA duplicates allows more exposure to mutations that could necessitate diversification, and possibly evolution, through sub- and neofunctionalization

    Randomized, open-label, phase 1/2a study to determine the maximum tolerated dose of intraventricular sustained release nimodipine for subarachnoid hemorrhage (NEWTON [Nimodipine Microparticles to Enhance Recovery While Reducing Toxicity After Subarachnoid Hemorrhage])

    Get PDF
    BACKGROUND AND PURPOSE—: We conducted a randomized, open-label, phase 1/2a, dose-escalation study of intraventricular sustained-release nimodipine (EG-1962) to determine safety, tolerability, pharmacokinetics, and clinical effects in aneurysmal subarachnoid hemorrhage. METHODS—: Subjects with aneurysmal subarachnoid hemorrhage repaired by clipping or coiling were randomized to EG-1962 or enteral nimodipine. Subjects were World Federation of Neurological Surgeons grade 2 to 4 and had an external ventricular drain. Cohorts of 12 subjects received 100 to 1200 mg EG-1962 (9 per cohort) or enteral nimodipine (3 per cohort). The primary objective was to determine the maximum tolerated dose. RESULTS—: Fifty-four subjects in North America were randomized to EG-1962, and 18 subjects were randomized to enteral nimodipine. The maximum tolerated dose was 800 mg. One serious adverse event related to EG-1962 (400 mg) and 2 EG-1962 dose-limiting toxicities were without clinical sequelae. There was no EG-1962-related hypotension compared with 17% (3/18) with enteral nimodipine. Favorable outcome at 90 days on the extended Glasgow outcome scale occurred in 27/45 (60%, 95% confidence interval 46%–74%) EG-1962 subjects (5/9 with 100, 6/9 with 200, 7/9 with 400, 4/9 with 600, and 5/9 with 800 mg) and 5/18 (28%, 95% confidence interval 7%–48%, relative risk reduction of unfavorable outcome; 1.45, 95% confidence interval 1.04–2.03; P=0.027) enteral nimodipine subjects. EG-1962 reduced delayed cerebral ischemia (14/45 [31%] EG-1962 versus 11/18 [61%] enteral nimodipine) and rescue therapy (11/45 [24%] versus 10/18 [56%]). CONCLUSIONS—: EG-1962 was safe and tolerable to 800 mg, and in this, aneurysmal subarachnoid hemorrhage population was associated with reduced delayed cerebral ischemia and rescue therapy. Overall, the rate of favorable clinical outcome was greater in the EG-1962-treated group. CLINICAL TRIAL REGISTRATION—: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01893190

    Barriers to development and progression of women entrepreneurs in Pakistan

    Get PDF
    This article would help integration of women entrepreneurs into the mainstream economy in Pakistan.In Pakistan, women entrepreneurs do not enjoy the same opportunities as men due to a number of deep-rooted discriminatory socio-cultural values and traditions. Furthermore, these restrictions can be observed within the support mechanisms that exist to assist such fledgling businesswomen. The economic potential of female entrepreneurs is not being realised as they suffer from a lack of access to capital, land, business premises, information technology, training and agency assistance. Inherent attitudes of a patriarchal society, that men are superior to women and that women are best suited to be homemakers, create formidable challenges. Women also receive little encouragement from some male family members, resulting in limited spatial mobility and a dearth of social capital. The research suggests that in order to foster development, multi-agency cooperation is required. The media, educational policy makers and government agencies could combine to provide women with improved access to business development services and facilitate local, regional and national networks

    The Place of Fish Production in a Program of Multiple Water Use

    Full text link
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142268/1/tafs0297.pd

    Untangling the Conceptual Isssues Raised in Reydon and Scholz’s Critique of Organizational Ecology and Darwinian Populations

    Get PDF
    Reydon and Scholz raise doubts about the Darwinian status of organizational ecology by arguing that Darwinian principles are not applicable to organizational populations. Although their critique of organizational ecology’s typological essentialism is correct, they go on to reject the Darwinian status of organizational populations. This paper claims that the distinction between replicators and interactors, raised in modern philosophy of biology but not discussed by Reydon and Scholz, points the way forward for organizational ecologists. It is possible to conceptualise evolving Darwinian populations providing the inheritance mechanism is appropriately specified. By this approach, adaptation and selection are no longer dichotomised, and the evolutionary significance of knowledge transmission is highlightedPeer reviewe

    A novel lineage of proteobacteria involved in formation of marine Fe-oxidizing microbial mat communities

    Get PDF
    © The Authors, 2007. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 2 (2007): e667, doi:10.1371/journal.pone.0000667.For decades it has been recognized that neutrophilic Fe-oxidizing bacteria (FeOB) are associated with hydrothermal venting of Fe(II)-rich fluids associated with seamounts in the world's oceans. The evidence was based almost entirely on the mineralogical remains of the microbes, which themselves had neither been brought into culture or been assigned to a specific phylogenetic clade. We have used both cultivation and cultivation-independent techniques to study Fe-rich microbial mats associated with hydrothermal venting at Loihi Seamount, a submarine volcano. Using gradient enrichment techniques, two iron-oxidizing bacteria, strains PV-1 and JV-1, were isolated. Chemolithotrophic growth was observed under microaerobic conditions; Fe(II) and Fe0 were the only energy sources that supported growth. Both strains produced filamentous stalk-like structures composed of multiple nanometer sized fibrils of Fe-oxyhydroxide. These were consistent with mineralogical structures found in the iron mats. Phylogenetic analysis of the small subunit (SSU) rRNA gene demonstrated that strains PV-1 and JV-1 were identical and formed a monophyletic group deeply rooted within the Proteobacteria. The most similar sequence (85.3% similarity) from a cultivated isolate came from Methylophaga marina. Phylogenetic analysis of the RecA and GyrB protein sequences confirmed that these strains are distantly related to other members of the Proteobacteria. A cultivation-independent analysis of the SSU rRNA gene by terminal-restriction fragment (T-RF) profiling showed that this phylotype was most common in a variety of microbial mats collected at different times and locations at Loihi. On the basis of phylogenetic and physiological data, it is proposed that isolate PV-1T ( = 1ATCC BAA-1019: JCM 14766) represents the type strain of a novel species in a new genus, Mariprofundus ferrooxydans gen. nov., sp. nov. Furthermore, the strain is the first cultured representative of a new candidatus class of the Proteobacteria that is widely distributed in deep-sea environments, Candidatus ζ (zeta)-Proteobacteria cl. nov.Funding was provided to DE and CLM by the National Science Foundation (0348330) and to DE through the NASA Astobiology Institute
    corecore