2,124 research outputs found

    Bridging the gap between small clusters and nanodroplets: spectroscopic study and computer simulation of carbon dioxide solvated with helium atoms.

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    High resolution infrared spectra of HeN–CO2 clusters with N up to about 20 have been studied in the region of the CO2 v3 fundamental band. The B rotational constant initially drops as expected for a normal molecule, reaching a minimum for N = 5. Its subsequent rise for N = 6 to 11 can be interpreted as the transition from a normal (though floppy) molecule to a quantum solvation regime. For N &#62; 13, the B value becomes approximately constant with a value about 17% larger than that measured in much larger helium nanodroplets. Quantum Monte Carlo calculations of pure rotational spectra are in excellent agreement with the measured B in this size range, and complement the experimental study with detailed structural information. For larger cluster size (N = 30-50) the simulations show a clear sign of convergence towards the nanodroplet B value.</p

    The spatiotemporal pattern of the human electroencephalogram at sleep onset after a period of prolonged wakefulness

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    During the sleep onset (SO) process, the human electroencephalogram (EEG) is characterized by an orchestrated pattern of spatiotemporal changes. Sleep deprivation (SD) strongly affects both wake and sleep EEG, but a description of the topographical EEG power spectra and oscillatory activity during the wake-sleep transition after a period of prolonged wakefulness is still missing. The increased homeostatic sleep pressure should induce an earlier onset of sleep-related EEG oscillations. The aim of the present study was to assess the spatiotemporal EEG pattern at SO following SD. A dataset of a previous study was analyzed. We assessed the spatiotemporal EEG changes (19 cortical derivations) during the SO (5 min before vs. 5 min after the first epoch of Stage 2) of a recovery night after 40 h of SD in 39 healthy subjects, analyzing the EEG power spectra (fast Fourier transform) and the oscillatory activity [better oscillation (BOSC) detection method]. The spatiotemporal pattern of the EEG power spectra mostly confirmed the changes previously observed during the wake-sleep transition at baseline. The comparison between baseline and recovery showed a wide increase of the post- vs. pre-SO ratio during the recovery night in the frequency bins 10 Hz. We found a predominant alpha oscillatory rhythm in the pre-SO period, while after SO the theta oscillatory activity was prevalent. The oscillatory peaks showed a generalized increase in all frequency bands from delta to sigma with different predominance, while beta activity increased only in the fronto-central midline derivations. Overall, the analysis of the EEG power replicated the topographical pattern observed during a baseline night of sleep but with a stronger intensity of the SO-induced changes in the frequencies 10 Hz, and the detection of the rhythmic activity showed the rise of several oscillations at SO after SD that was not observed during the wake-sleep transition at baseline (e.g., alpha and frontal theta in correspondence of their frequency peaks). Beyond confirming the local nature of the EEG pattern at SO, our results show that SD has an impact on the spatiotemporal modulation of cortical activity during the falling-asleep process, inducing the earlier emergence of sleep-related EEG oscillations

    Comparative evaluation of the biofloc system versus the recirculation system with Macrobrachium amazonicum / Avaliação comparativa do sistema bioflocos versus o sistema de recirculação com Macrobrachium amazonicum

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    The aim of this study was to evaluate the efficiency of the biofloc system versus the recirculation system using the native Amazonian freshwater shrimp Macrobrachium amazonicum (Heller, 1862) as a cultivation organism.  In this initial evaluation, the water quality parameters of each system were measured and the survival rate in the biofloc system showed similar values for M. amazonicum grown in a super-intensive recirculation system with averages values of 60%. The results indicated that both systems were within acceptable limits in terms of parameters (physical-chemical) and the survival rate of both systems showed similar values for M. amazonicum

    Avaliação descritiva das características morfométricas de camarões canela Macrobrachium amazonicum que não sobreviveram durante o período de aclimatação

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    O objetivo deste estudo foi descrever as características morfométricas de camarões canela, Macrobrachium amazonicum (Heller, 1862) que não sobreviveram ao período de aclimatação que precedeu ao cultivo de bioflocos. As características morfométricas analisadas de duas amostras, uma com 11 machos e outra com 7 fêmeas foram as variáveis peso total, comprimento total e comprimento do cefalotórax. Os resultados avaliados indicaram que o peso total médio das fêmeas foi maior que nos machos, e tanto o comprimento total médio quanto o comprimento do cefalotórax médio entre os sexos não variaram de forma significativa conforme o teste t de Student. Na análise separada por sexo os testes de correlação de Pearson foram significativos para o peso total versus o comprimento total obtendo-se equações de regressões para a estimação de valores de peso total.&nbsp

    A multi-society position paper on the prevention and management of nosocomial and severe infections: the Italian Society for Infectious Diseases, the Italian Multidisciplinary Society of Hospital Infections, the Italian Society of Chemotherapy, the Italian Society of Respiratory Medicine, the Italian Society of Clinical Microbiology, the Italian Society of Microbiology, and GISIG (Italian Study Group on Severe Infections)

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    Amulti-society position paper on the prevention and management of nosocomial and severe infections: the Italian Society for Infectious Diseases, the Italian Multidisciplinary Society of Hospital Infections, the Italian Society of Chemotherapy, the Italian Society of Respiratory Medicine, the Italian Society of Clinical Microbiology, the Italian Society of Microbiology, and GISIG (Italian Study Group on Severe Infections
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