927 research outputs found

    Design with a Positive Lens: An affirmative approach to designing information and organizations

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    Design forms one critical paradigmatic view that pervades organizational studies, management, and information systems research. Building on the discussions in the First Working Conference on Designing Information and Organizations with a Positive Lens, we chart the potential contribution of positive design to the shaping of organizations, work processes, artifacts, communication networks, and information technologies. The figure of speech "Design with a Positive Lens," or in short, "Positive Design," connotes here a distinctive perspective on design that is less focused on the detection of errors associated with gaining control and more concerned with human-centered design associated with the shaping of hopeful organizations and a thriving future. The paper examines how positive design can contribute to the design of information systems and organizations as related to five broad-scale areas: design of high performance work processes; positive design methods and techniques: cooperation and collaboration across boundaries to promote positive change; positive organizational design, and design science and practice. In this paper we aspire to promote the emerging cross-disciplinary discourse between scholars and designers that will foster positive organizational and technological design

    Membrane permeability of small molecules from unbiased molecular dynamics simulations

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    Permeation of many small molecules through lipid bilayers can be directly observed in molecular dynamics simulations on the nano- and microsecond timescale. While unbiased simulations provide an unobstructed view of the permeation process, their feasibility for computing permeability coefficients depends on various factors that differ for each permeant. The present work studies three small molecules for which unbiased simulations of permeation are feasible within less than a microsecond, one hydrophobic (oxygen), one hydrophilic (water), and one amphiphilic (ethanol). Permeabilities are computed using two approaches: counting methods and a maximum-likelihood estimation for the inhomogeneous solubility diffusion (ISD) model. Counting methods yield nearly model-free estimates of the permeability for all three permeants. While the ISD-based approach is reasonable for oxygen, it lacks precision for water due to insufficient sampling and results in misleading estimates for ethanol due to invalid model assumptions. It is also demonstrated that simulations using a Langevin thermostat with collision frequencies of 1/ps and 5/ps yield oxygen permeabilities and diffusion constants that are lower than those using Nose-Hoover by statistically significant margins. In contrast, permeabilities from trajectories generated with Nose-Hoover and the microcanonical ensemble do not show statistically significant differences. As molecular simulations become more affordable and accurate, calculation of permeability for an expanding range of molecules will be feasible using unbiased simulations. The present work summarizes theoretical underpinnings, identifies pitfalls, and develops best practices for such simulations

    Water Vapor Measurements by Howard University Raman Lidar during the WAVES 2006 Campaign

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    Retrieval of water vapor mixing ratio using the Howard University Raman Lidar is presented with emphasis on three aspects: i) performance of the lidar against collocated radiosondes and Raman lidar, ii) investigation of the atmospheric state variables when poor agreement between lidar and radiosondes values occurred and iii) a comparison with satellite-based measurements. The measurements were acquired during the Water Vapor Validation Experiment Sondes/Satellites 2006 field campaign. Ensemble averaging of water vapor mixing ratio data from ten night-time comparisons with Vaisala RS92 radiosondes shows on average an agreement within 10 % up to approx. 8 km. A similar analysis of lidar-to-lidar data of over 700 profiles revealed an agreement to within 20 % over the first 7 km (10 % below 4 km). A grid analysis, defined in the temperature - relative humidity space, was developed to characterize the lidar - radiosonde agreement and quantitatively localizes regions of strong and weak correlations as a function of altitude, temperature or relative humidity. Three main regions of weak correlation emerge: i) regions of low relative humidity and low temperature, ii) moderate relative humidity at low temperatures and iii) low relative humidity at moderate temperatures. Comparison of Atmospheric InfraRed Sounder and Tropospheric Emission Sounder satellites retrievals of moisture with that of Howard University Raman Lidar showed a general agreement in the trend but the formers miss a lot of the details in atmospheric structure due to their low resolution. A relative difference of about 20 % is usually found between lidar and satellites measurements

    Volume-energy correlations in the slow degrees of freedom of computer-simulated phospholipid membranes

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    Constant-pressure molecular-dynamics simulations of phospholipid membranes in the fluid phase reveal strong correlations between equilibrium fluctuations of volume and energy on the nanosecond time-scale. The existence of strong volume-energy correlations was previously deduced indirectly by Heimburg from experiments focusing on the phase transition between the fluid and the ordered gel phases. The correlations, which are reported here for three different membranes (DMPC, DMPS-Na, and DMPSH), have volume-energy correlation coefficients ranging from 0.81 to 0.89. The DMPC membrane was studied at two temperatures showing that the correlation coefficient increases as the phase transition is approached

    Langevin network model of myosin

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    Langevin mode theory and the coarse-grained elastic network model (ENM) for proteins are combined to yield the Langevin network model (LNM). Hydrodynamic radii of 6 Ã… were assigned to each R-carbon on the basis of matching experimental translational and rotational diffusion constants of lysozyme, myoglobin, and hemoglobin with those calculated using a rigid body bead model with hydrodynamic interactions described by the Rotne-Prager tensor. LNM analysis of myosin II indicates that all ENM-like modes are overdamped at water viscosities. The low-frequency LNM modes in the pre-power stroke structure (PDB code: 1VOM) are substantially less mixed than the corresponding modes of the post-power stroke structure (1Q5G). Results from a four-bead model of the myosin "lever arm" indicate that coupling between modes increases as the array departs from linearity and are consistent with the results for 1VOM and 1Q5G. The decay times for all overdamped Langevin modes are shorter than the calculated rotational tumbling times found for lysozyme and myosin

    Innovations in Pharmacy through Practice-Based Research

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    The overall purpose of this article is to serve as an invitation for submissions to the 'Practice-Based Research' section of INNOVATIONS in pharmacy. To provide background about this section of the journal, this paper describes: (1) the concept of innovations that we will apply, (2) the practice-based research domain, and (3) the use of practice-based research networks for this area of inquiry. We propose that uncertainty surrounding an innovation often will result in the postponement of the decision regarding its adoption until further evidence can be obtained. Such evidence often is gathered through considering the advice and experiences of opinion leaders and members of social systems who have adopted the innovation. We invite authors to present ideas, arguments, and evidence for innovations in pharmacy that arise out of practice-based research. We propose that this journal will be an excellent communication vehicle for providing convincing arguments and sound evidence in favor of innovations. Discourse regarding new ideas in such a format can further develop the ideas, create a critical mass of evidence, and be used for convincing others that the innovation should be adopted. We welcome submissions to the INNOVATIONS in pharmacy, PRACTICE-BASED RESEARCH content area that: (1) provide convincing arguments and sound evidence in favor of innovations for pharmacy, (2) are based upon practice-based research from case studies of single patients on one end of the continuum to findings from large populations of patients on the other end of the continuum, and/or (3) introduce innovations for practice-based research networks. We encourage articles from all perspectives and from all methods of inquiry. Type: Invitatio

    ¿Puede la disponibilidad temporal de datos determinar el calentamiento percibido por las tribus nómadas de mongoles cerca de las montañas Khangai?

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    Temperatures changes can be difficult to infer from changes in vegetation patterns or other ecological changes, yet warming can be inferred through changes in the habits of people who live in close connection with their natural environment. Herders near the Khangai Mountains of central Mongolia have perceived a warming trend in recent years. Since it is difficult to determine the exact time period over which perceived warming has occurred, we examined the statistical difference in changes based on the length of data and the specific period of record used in the analysis. We used temperature data from five meteorological stations for up to 50 years (1961-2010). We examined varying lengths of record from 15 to 50 years with varying start periods (1961 through 1986), based on the length of record. We found that the most statistically significant changes occurred for the longest time periods and for the annual average minimum temperatures. We also found that one very cold winter, in particular 2009-2010 decreased the warming trend and for shorter periods of record reduced the statistical significance.Los cambios de temperatura pueden ser difíciles de inferir a partir de los cambios en los patrones de vegetación u otros cambios ecológicos. Sin embargo, el calentamiento se puede inferir a través de cambios en los hábitos de las personas que viven en estrecha relación con su entorno natural. Los pastores de las montañas de Mongolia central, cerca deKhangai, perciben una tendencia hacia el calentamiento en los últimos años. Ya que resulta difícil determinar el período de tiempo exacto durante el que se ha producido el calentamiento, se analizó la diferencia estadística de los cambios en función de la longitud de los datos y el período de registros utilizado en el análisis. Hemos utilizado los datos de temperatura de cinco estaciones meteorológicas con 50 años de registros (1961-2010). Se examinaron diferentes longitudes de registro (de 15 a 50 años) con períodos de inicio diferentes (1961 a 1986). Se comprobó que los cambios estadísticamente más significativos se registran en los períodos más largos y considerando las temperaturas mínimas medias anuales. También se encontró que un invierno muy frío, en particular (2009-2010) disminuyó la tendencia al calentamiento
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