481 research outputs found

    Defect-unbinding transitions and inherent structures in two dimensions

    Full text link
    We present a large-scale (36000-particle) computational study of the "inherent structures" (IS) associated with equilibrium, two-dimensional, one-component Lennard-Jones systems. Our results provide strong support both for the inherent-structures theory of classical fluids, and for the KTHNY theory of two-stage melting in two dimensions. This support comes from the observation of three qualitatively distinct "phases" of inherent structures: a crystal, a "hexatic glass", and a "liquid glass". We also directly observe, in the IS, analogs of the two defect-unbinding transitions (respectively, of dislocations, and disclinations) believed to mediate the two equilibrium phase transitions. Each transition shows up in the inherent structures---although the free disclinations in the "liquid glass" are embedded in a percolating network of grain boundaries. The bond-orientational correlation functions of the inherent structures show the same progressive loss of order as do the three equilibrium phases: long-range to quasi-long-range to short-range.Comment: RevTeX, 8 pages, 15 figure

    Binuclear Manganese(III) Complexes as Electron Donors in D1/D2/Cytochrome b559 Preparations Isolated from Spinach Photosystem II Membrane Fragments

    Get PDF
    The capability of different manganese complexes to act as PS II electron donors in D1/D2/ cytochrome b 559 complexes has been analyzed by measuring actinic light-induced absorption changes at 680 nm (650 nm) and 340 nm, reflecting the photoaccumulation of Pheophytin- (Pheo-) and the reduction of NADP+ respectively. The data obtained reveal: a) the donor capacity of synthetic binuclear Mn(III)2 complexes containing aromatic ligands significantly exceeds that for MnCl2 in both cases, i.e. Pheo- photoaccumulation and NADP+ reduction; b) manganese complexes can serve as suitable electron donors for light-induced NADP+ reduction catalyzed by D1/D2/cytochrome b559 complexes and ferredoxin plus ferredoxin- NADP+ reductase under anaerobic conditions and c) the specific turnover rate of the system leading to NADP+ reduction is extremely small. The implications of these findings are briefly discussed

    RXTE Absolute Timing Results for the Pulsars B1821-24 and B1509-58

    Get PDF
    Observations with the Rossi X-ray Timing Explorer and the Jodrell Bank, Parkes, and Green Bank telescopes have enabled us to determine the time delay between radio and X-ray pulses in the two isolated pulsars B1821-24 and B1509-58. For the former we find that the narrow X-ray and radio pulse components are close to being coincident in time, with the radio peak leading by 0.02 period (60 +/- 20 microsec), while the wide X-ray pulse component lags the last of the two wider radio components by about 0.08 period. For the latter pulsar we find, using the standard value for the dispersion measure, that the X-ray pulse lags the radio by about 0.27 period, with no evidence for any energy-dependence in the range 2-100 keV. However, uncertainties in the history of the dispersion measure for this pulsar make a comparison with previous results difficult. It is clear that there are no perceptable variations in either the lag or the dispersion measure at time scales of a year or less.Comment: 20 pages including 6 figures, accepted by Astrophysical Journa

    Cama de frango como substrato para a produção de biogás após diferentes períodos de estocagem.

    Get PDF
    RESUMO: Na avicultura a cama de frango é produzida sazonalmente, em função do modo de produção. Para obter energia do biogás por meio da biodigestão da cama de frango, de forma contínua, o armazenamento do resíduo pode ser uma solução. Ensaios de Potencial Bioquímico de Metano (BMP) foram utilizados neste trabalho para estimar a capacidade de produção de biogás e metano da cama de frango removida após o sexto lote de reutilização e a diferentes tempos de armazenamento após a coleta, assim, verificar a viabilidade de utilização da cama de frango como um substrato em unidade produtora de biogás. A produção de biogás e metano, nas amostras em diferentes períodos de armazenamento, foi comparada: antes de armazenar 245 LN biogas.kgSV adic-1 e 159 LN CH4.kgSV adic-11, seis meses com 252 LN biogas.kgSV adic-1 e 160 LN CH4.kgSV adic-1 e um ano 209 LN biogas.kgSV adic-1 e 117 LNCH4.kgSV adic-1, demonstrando que o período de armazenamento é caracterizado por uma relativa perda do conteúdo de matéria orgânica após um ano, contudo, não há diferença significativa entre a produção de biogás e metano após seis meses armazenada e antes de armazenar. Verificou-se a viabilidade da estocagem de cama de frango do sexto lote de reutilização, no período de seis meses, sem perda significativa de matéria orgânica para a conversão em biogás e metano. ABSTRACT: In poultry litter is produced seasonally due to production mode. To get energy from biogas through the bio digestion of poultry litter, continuously, the storage of the residue can be a solution. Biochemical Methane Potential (BMP) assays were used in this study to estimate the production of biogas and methane poultry litter removed after the sixth lot of reuse and in different storage times after collect, so check the feasibility of use poultry litter as a feedstock in biogas producer unit. The production of biogas and methane in the samples in different periods of storage was compared: before storage 245 LN biogas.kgVS add-1 E 159 LN C H4 kg SV add-1, six months with 252 LN biogas.kgVS add-1 e 160 LN C H4 kg SV add-1 and a year 209 LN biogas.kgVS add-1 and one year 117 LN C H4 kg SV add-1, demonstrating that the storage period is characterized by a relative loss of content of organic matter after a year, however there's no significant difference between the production of biogas and methane in six months storaged and before storage . It was verified the viability of storage of poultry litter of the sixth lot of reuse, in the six-month period, without significant loss of organic matter for conversion to biogas and methane

    Non-syndromic Sensorineural Prelingual Deafness: The Importance of Genetic Counseling in Demystifying Parents’ Beliefs About the Cause of Their Children’s Deafness

    Get PDF
    Recent advances in molecular genetics have allowed the determination of the genetic cause of some childhood non-syndromic deafness. In Portugal only a small proportion of families are referred to a clinical genetics service in order to clarify the etiology of the deafness and to provide genetic counseling. Consequently, there are no published studies of the prior beliefs of parents about the causes of hereditary deafness of their children and their genetic knowledge after receipt of genetic counseling. In order to evaluate the impact of genetic counseling, 44 parents of 24 children with the diagnosis of non-syndromic sensorineural prelingual deafness due to mutations in the GJB2 (connexin 26), completed surveys before and after genetic counseling. Before counseling 13.6 % of the parents knew the cause of deafness; at a post-counseling setting this percentage was significantly higher, with 84.1 % of the parents accurately identifying the etiology. No significant differences were found between the answers of mothers and fathers either before or after genetic counseling. Parents' level of education was a significant factor in pre-test knowledge. After genetic counseling 95.5 % of the parents stated that the consultation had met their expectations, 70.5 % remembered correctly the inheritance pattern, and 93.2 % correctly recalled the chance of risk of deafness. These results underline the importance of genetic counseling in demystifying parents' beliefs about the etiology of their children's deafness

    Association of Atopobium vaginae, a recently described metronidazole resistant anaerobe, with bacterial vaginosis

    Get PDF
    BACKGROUND: Bacterial vaginosis (BV) is a polymicrobial syndrome characterized by a change in vaginal flora away from predominantly Lactobacillus species. The cause of BV is unknown, but the condition has been implicated in diverse medical outcomes. The bacterium Atopobium vaginae has been recognized only recently. It is not readily identified by commercial diagnostic kits. Its clinical significance is unknown but it has recently been isolated from a tuboovarian abcess. METHODS: Nucleotide sequencing of PCR amplified 16S rRNA gene segments, that were separated into bands within lanes on polyacrylamide gels by denaturing gradient gel electrophoresis (DGGE), was used to examine bacterial vaginal flora in 46 patients clinically described as having normal (Lactobacillus spp. predominant; Nugent score ≤ 3) and abnormal flora (Nugent score ≥ 4). These women ranged in age from 14 to 48 and 82% were African American. RESULTS: The DGGE banding patterns of normal and BV-positive patients were recognizably distinct. Those of normal patients contained 1 to 4 bands that were focused in the centre region of the gel lane, while those of BV positive patients contained bands that were not all focused in the center region of the gel lane. More detailed analysis of patterns revealed that bands identified as Atopobium vaginae were present in a majority (12/22) of BV positive patients, while corresponding bands were rare (2/24) in normal patients. (P < 0.001) Two A. vaginae isolates were cultivated from two patients whose DGGE analyses indicated the presence of this organism. Two A. vaginae 16S rRNA gene sequences were identified among the clinical isolates. The same two sequences were obtained from DGGE bands of the corresponding vaginal flora. The sequences differed by one nucleotide over the short (~300 bp) segment used for DGGE analysis and migrated to slightly different points in denaturing gradient gels. Both isolates were strict anaerobes and highly metronidazole resistant. CONCLUSION: The results suggest that A. vaginae may be an important component of the complex bacterial ecology that constitutes abnormal vaginal flora. This organism could play a role in treatment failure if further studies confirm it is consistently metronidozole resistant

    Happiness around the world: A combined etic-emic approach across 63 countries

    Get PDF
    What does it mean to be happy? The vast majority of cross-cultural studies on happiness have employed a Western-origin, or "WEIRD" measure of happiness that conceptualizes it as a self-centered (or "independent"), high-arousal emotion. However, research from Eastern cultures, particularly Japan, conceptualizes happiness as including an interpersonal aspect emphasizing harmony and connectedness to others. Following a combined emicetic approach (Cheung, van de Vijver &amp; Leong, 2011), we assessed the cross-cultural applicability of a measure of independent happiness developed in the US (Subjective Happiness Scale; Lyubomirsky &amp; Lepper, 1999) and a measure of interdependent happiness developed in Japan (Interdependent Happiness Scale; Hitokoto &amp; Uchida, 2015), with data from 63 countries representing 7 sociocultural regions. Results indicate that the schema of independent happiness was more coherent in more WEIRD countries. In contrast, the coherence of interdependent happiness was unrelated to a country's "WEIRD-ness." Reliabilities of both happiness measures were lowest in African and Middle Eastern countries, suggesting these two conceptualizations of happiness may not be globally comprehensive. Overall, while the two measures had many similar correlates and properties, the self-focused concept of independent happiness is "WEIRD-er" than interdependent happiness, suggesting cross-cultural researchers should attend to both conceptualizations

    Triple negative breast cancer: proposals for a pragmatic definition and implications for patient management and trial design.

    Get PDF
    In trials in triple negative breast cancer (TNBC), oestrogen and progesterone receptor negativity should be defined as < 1% positive cells. Negativity is a ratio of <2 between Her2 gene copy number and centromere of chromosome 17 or a copy number of 4 or less. In routine practice, immunohistochemistry is acceptable given stringent quality assurance. Triple negativity emerging after neoadjuvant treatment differs from primary TN and such patients should not enter TNBC trials. Patients relapsing with TN metastases should be eligible even if their primary was positive. Rare TN subtypes such as apocrine, adenoid-cystic and low-grade metaplastic tumours should be excluded. TN and basal-like (BL) signatures overlap but are not equivalent. Since the significance of basal cytokeratin or EGFR overexpression is not known and we lack validated assays, these features should not be used to subclassify TN tumours. Tissue collection in trials is mandatory so the effect on outcome of different tumour phenotypes and BRCA mutation can be explored. No prospective studies have established that TN tumours have particular sensitivity or resistance to any specific chemotherapy agent or radiation. TNBC patients should be treated according to tumour and clinical characteristics
    • …
    corecore