1,262 research outputs found

    A theoretical simulation of the resonant Raman spectroscopy of the H2O⋯Cl2 and H2O⋯Br2 halogen-bonded complexes

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    The resonant Raman spectra of the H2O⋯Cl2 and H2O⋯Br2 halogen-bonded complexes have been studied in the framework of a 2-dimensional model previously used in the simulation of their UV-visible absorption spectra using time-dependent techniques. In addition to the vibrational progression along the dihalogen mode, a progression is observed along the intermolecular mode and its combination with the intramolecular one. The relative intensity of the inter to intramolecular vibrational progressions is about 15% for H2O⋯Cl2 and 33% for H2O⋯Br2. These results make resonant Raman spectra a potential tool for detecting the presence of halogen bonded complexes in condensed phase media such as clathrates and ice.Fil: Franklin Mergarejo, Ricardo. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; Francia. InSTEC; Cuba. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rubayo Soneira, Jesús. InSTEC; CubaFil: Halberstadt, Nadine. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; FranciaFil: Janda, Kenneth C.. University of California at Irvine; Estados UnidosFil: Apkarian, V. Ara. University of California at Irvine; Estados Unido

    Growth of bifidobacteria in mammalian milk

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    Microbial colonization of the mammalian intestine begins at birth, when from a sterile state a newborn infant is exposed to an external environment rich in various bacterial species. An important group of intestinal bacteria comprises bifidobacteria. Bifidobacteria represent major intestinal microbiota during the breast-feeding period. Animal milk contains all crucial nutrients for babies’ intestinal microflora. The aim of our work was to test the influence of different mammalian milk on the growth of bifidobacteria. The growth of seven strains of bifidobacteria in human milk, the colostrum of swine, cow’s milk, sheep’s milk, and rabbit’s milk was tested. Good growth accompanied by the production of lactic acid was observed not only in human milk, but also in the other kinds of milk in all three strains of Bifidobacterium bifidum of different origin. Human milk selectively supported the production of lactic acid of human bifidobacterial isolates, especially the Bifidobacterium bifidum species. The promotion of bifidobacteria by milk is species-specific. Human milk contains a key factor for the growth of specific species or strains of human-origin bifidobacteria compared to other kinds of milk. In contrast, some components (maybe lysozyme) of human milk inhibited the growth of Bifidobacterium animalis. Animal-origin strains of bifidobacteria were not able to significantly grow even in milk of animal origin, with the exception of B. animalis subsp. lactis 1,2, which slightly grew in sheep’s milk

    Muscle recruitment patterns during the prone leg extension

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    BACKGROUND: The prone leg extension (PLE) is a clinical test used to evaluate the function of the lumbopelvis. It has been theorized that a normal and consistent pattern of muscle activation exists. Previous research has found two contradictory patterns of muscle activation during PLE in normal individuals. One study shows an almost simultaneous activation of the lower erector spinae and hamstring muscle group with a delayed activation of the gluteus maximus, while the second describes the order of activation being ipsilateral erector spinae (to the leg being extended), hamstrings, contralateral erector spinae and gluteus maximus. Due to the different conclusions from these two studies and the lack of quantified muscle onset times, expressed in absolute time this study attempted to quantify the muscle onset times (in milliseconds) during the prone leg extension, while noting if a consistent order of activation exists and whether a timing relationship also exists between the gluteus maximus and contralateral latissimus dorsi. METHODS: 10 asymptomatic males (Average height: 175.2 cm (SD 6.5), Average Weight 75.9 kg (SD 6.5), Average Age: 27.1(SD 1.28)) and 4 asymptomatic females (Average height 164.5 (SD 2.9), weight: 56.2 (SD 8.9), Average Age: 25 (SD 1)) performed the prone leg extension task while the myoelectric signal was recorded from the bilateral lower erector spinae, gluteus maximus and hamstring muscle groups. Activation onsets were determined from the rectified EMG signal relative to the onset of the hamstrings muscle group. RESULTS: No consistent recruitment patterns were detected for prone leg extension among the hamstring muscle group and the erector spinae. However, a consistent delay in the Gluteus Maximus firing of approximately 370 ms after the first muscle activated was found. Five out of 14 asymptomatic subjects showed a delay in gluteus maximus firing exceeding the average delay found in previous research of subjects considered to have a dysfunctional firing pattern. CONCLUSION: A consistent pattern of activation was not found. Variability was seen across subjects. These findings suggest the PLE is not sufficient for a diagnostic test due to the notable physiological variation. An overlap between normal and potentially abnormal activation patterns may exist

    What constructional profiles reveal about synonymy: A case study of Russian words for sadness and happiness

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    We test two hypotheses relevant to the form-meaning relationship and offer a methodological contribution to the empirical study of near-synonymy within the framework of cognitive linguistics. In addition, we challenge implicit assumptions about the nature of the paradigm, which we show is skewed in favor of a few forms that are prototypical for a given lexical item. If one accepts the claim of construction grammar that the construction is the relevant unit of linguistic analysis, then we should expect to find a relationship between the meanings of words and the constructions they are found in. One way to investigate this expectation is by examining the meaning of constructions on the basis of their lexical profile; this line of research is pursued in collostructional analyses. We have taken a different approach, examining the meaning of near-synonyms on the basis of what we call their "constructional profile". We define a constructional profile as the frequency distribution of the constructions that a word appears in. Constructional profiles for Russian nouns denoting sadness and happiness are presented, based upon corpus data, and analyzed quantitatively (using chi square and hierarchical cluster analysis). The findings are compared to the introspective analyses offered in synonym dictionaries. © 2009 by Walter de Gruyter GmbH

    Growth of bifidobacteria in mammalian milk

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    Microbial colonization of the mammalian intestine begins at birth, when from a sterile state a newborn infant is exposed to an external environment rich in various bacterial species. An important group of intestinal bacteria comprises bifidobacteria. Bifidobacteria represent major intestinal microbiota during the breast-feeding period. Animal milk contains all crucial nutrients for babies’ intestinal microflora. The aim of our work was to test the influence of different mammalian milk on the growth of bifidobacteria. The growth of seven strains of bifidobacteria in human milk, the colostrum of swine, cow’s milk, sheep’s milk, and rabbit’s milk was tested. Good growth accompanied by the production of lactic acid was observed not only in human milk, but also in the other kinds of milk in all three strains of Bifidobacterium bifidum of different origin. Human milk selectively supported the production of lactic acid of human bifidobacterial isolates, especially the Bifidobacterium bifidum species. The promotion of bifidobacteria by milk is species-specific. Human milk contains a key factor for the growth of specific species or strains of human-origin bifidobacteria compared to other kinds of milk. In contrast, some components (maybe lysozyme) of human milk inhibited the growth of Bifidobacterium animalis. Animal-origin strains of bifidobacteria were not able to significantly grow even in milk of animal origin, with the exception of B. animalis subsp. lactis 1,2, which slightly grew in sheep’s milk

    Molecular Techniques Reveal Wide Phyletic Diversity of Heterotrophic Microbes Associated with Discodermia spp. (Porifera: Demospongiae)

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    Sponges are well known to harbor large numbers of heterotrophic microbes within their mesohyl. Studies to determine the diversity of these associated microbes have been attempted for only a few shallow water species. We cultured various microorganisms from several species of Discodermia collected from deep water using the \u27Johnson-Sea-Link\u27 manned submersibles, and characterised them by standard microbiological identification methods. Characterisation of a small proportion (ca. 10%) of the total and potential eubacterial isolate collection with molecular systematics techniques revealed a wide diversity of microbes. Phylogenetic analyses of 32 small subunit (SSU) 16S-like rRNA gene sequences from different micorbes indicated high levels of taxonomic diversity assoiated with this genus of sponge. For example, bacteria from at least five cubacterial subdivisions - gamma, alpha, beta, Cytophaga and Gram positive - were isolated from the mesohyl of Discodermia. Several strains were unidentifiable from current sequence databases. No overlap was found between sequences of 24 isolates and 8 sequences obtained by PCR and cloning directly from sponge samples. The abundance and diversity of microbes associated with sponges such as Discodermia suggest that they may play important roles in marine microbial ecology, dispersal and evolution

    Enhancement of the spin Hall voltage in a reverse-biased planar p-n junction

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    We report an experimental demonstration of a local amplification of the spin Hall voltage using an expanding depletion zone at a p-n junction in GaAs/AlGaAs Hall-bar microdevices. It is demonstrated that the depletion zone can be spatially expanded by applying reverse bias by at least 10 μm at low temperature. In the depleted regime, the spin Hall signals reached more than one order of magnitude higher values than in the normal regime at the same electrical current flowing through the microdevice. It is shown that the p-n bias has two distinct effects on the detected spin Hall signal. It controls the local drift field at the Hall cross which is highly nonlinear in the p-n bias due to the shift of the depletion front. Simultaneously, it produces a change in the spin-transport parameters due to the nonlinear change in the carrier density at the Hall cross with the p-n bias
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