1,711 research outputs found

    Performance Evaluation of Road Traffic Control Using a Fuzzy Cellular Model

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    In this paper a method is proposed for performance evaluation of road traffic control systems. The method is designed to be implemented in an on-line simulation environment, which enables optimisation of adaptive traffic control strategies. Performance measures are computed using a fuzzy cellular traffic model, formulated as a hybrid system combining cellular automata and fuzzy calculus. Experimental results show that the introduced method allows the performance to be evaluated using imprecise traffic measurements. Moreover, the fuzzy definitions of performance measures are convenient for uncertainty determination in traffic control decisions.Comment: The final publication is available at http://www.springerlink.co

    Optical structure and function of the white filamentary hair covering the edelweiss bracts

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    The optical properties of the inflorescence of the high-altitude ''Leontopodium nivale'' subsp. ''alpinum'' (edelweiss) is investigated, in relation with its submicrometer structure, as determined by scanning electron microscopy. The filaments forming the hair layer have been found to exhibit an internal structure which may be one of the few examples of a photonic structure found in a plant. Measurements of light transmission through a self-supported layer of hair pads taken from the bracts supports the idea that the wooly layer covering the plant absorbs near-ultraviolet radiation before it reaches the cellular tissue. Calculations based on a photonic-crystal model provides insight on the way radiation can be absorbed by the filamentary threads.Comment: 9 pages, 13 figures. Published pape

    Effect of intraoperative fluid optimisation on renal function in patients undergoing emergency abdominal surgery; a randomised controlled pilot study (ISRCTN 11799696) Fluid optimisation for emergency surgery

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    <b>Background:</b> Emergency abdominal surgery carries a high risk of postoperative morbidity and mortality. Goal directed therapy has been advocated to improve outcome in high-risk surgery. The aim of the present pilot study was to examine the effect of goal directed therapy using fluid alone on postoperative renal function and organ failure score in patients undergoing emergency abdominal surgery. <b>Methods:</b> This prospective randomised pilot study included patients over the age of 50 undergoing emergency abdominal surgery. In the intervention group pulse pressure variation measurements were used to guide fluid boluses of 6% Hydroxyethylstarch 130/0.4. The control group received standard care. Serum urea, creatinine and cystatin C levels were measured prior to and at the end of surgery and postoperatively on day 1, day 3 and day 5. <b>Results:</b> Thirty patients were recruited. One patient died prior to surgery and was excluded from the analysis. The intervention group received a median of 750ml of hydroxyethylstarch. The peak values of postoperative urea were 6.9 (2.7–31.8) vs. 6.4 (3.5–11.5)mmol/l (p=0.425), creatinine 100 (60–300) vs. 85 (65–150) μmol/l (p=0.085) and cystatin C 1.09 (0.66–4.94) vs. 1.01 (0.33–2.29)mg/dl (p=0.352) in the control and intervention group, respectively. <b>Conclusions:</b> In the present pilot study replacing the identified fluid deficit was not associated with a change in renal function. These results do not preclude that goal directed therapy using fluid alone may have an effect on renal function but they would suggest that the effect size of fluid optimisation alone on renal function is small

    Dielectric relaxation of DNA aqueous solutions

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    We report on a detailed characterization of complex dielectric response of Na-DNA aqueous solutions by means of low-frequency dielectric spectroscopy (40 Hz - 110 MHz). Results reveal two broad relaxation modes of strength 20<\Delta\epsilon_LF<100 and 5<\Delta\epsilon_HF<20, centered at 0.5 kHz<\nu_LF<70 kHz and 0.1 MHz<\nu_HF<15 MHz. The characteristic length scale of the LF process, 50<L_LF<750nm, scales with DNA concentration as c_DNA^{-0.29\pm0.04} and is independent of the ionic strength in the low added salt regime. Conversely, the measured length scale of the LF process does not vary with DNA concentration but depends on the ionic strength of the added salt as I_s^{-1} in the high added salt regime. On the other hand, the characteristic length scale of the HF process, 3<L_HF<50 nm, varyes with DNA concentration as c_DNA^{-0.5} for intermediate and large DNA concentrations. At low DNA concentrations and in the low added salt limit the characteristic length scale of the HF process scales as c_DNA^{-0.33}. We put these results in perspective regarding the integrity of the double stranded form of DNA at low salt conditions as well as regarding the role of different types of counterions in different regimes of dielectric dispersion. We argue that the free DNA counterions are primarily active in the HF relaxation, while the condensed counterions play a role only in the LF relaxation. We also suggest theoretical interpretations for all these length scales in the whole regime of DNA and salt concentrations and discuss their ramifications and limitations.Comment: 15 pages, 9 figure

    Creative leisure activities, mental health and well-being during 5 months of the COVID-19 pandemic: a fixed effects analysis of data from 3725 US adults

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    Introduction: We investigated whether changes in engagement in home-based creative activities were associated with changes in depressive symptoms, anxiety symptoms and life satisfaction during the COVID-19 pandemic, aiming to replicate findings from the UK in a USA sample. Methods: 3725 adults were included from the COVID-19 Social Study in the USA, a panel study collecting data weekly during the COVID-19 pandemic. We measured engagement in eight types of creative leisure activities on the previous weekday between April and September 2020. Data were analysed using fixed effects regression models. Results: Increased time spent gardening was associated with reductions in depressive and anxiety symptoms and enhanced life satisfaction. Spending more time doing woodwork/DIY and arts/crafts were also associated with enhanced life satisfaction. However, more time watching television, films or other similar media (not for information on COVID-19) was associated with increased depressive symptoms. Other creative activities were not associated with mental health or well-being. Conclusion: Some findings differ from evidence obtained in the UK, demonstrating the importance of replicating research across countries. Our findings should also be considered when formulating guidelines for future stay-at-home directives, enabling individuals to stay well despite the closure of public resources

    Effects of increase in temperature and open water on transmigration and access to health care by the Nenets reindeer herders in northern Russia

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    Background . The indigenous Nenets reindeer herders in northern Russia annually migrate several hundred kilometers between summer and winter pastures. In the warming climate, ice-rich permafrost and glaciers are being significantly reduced and will eventually disappear from parts of the Arctic. The emergent changes in hydrological cycles have already led to substantial increases in open water that stays unfrozen for longer periods of time. This environmental change has been reported to compromise the nomadic Nenets&#x2019; traditional way of life because the presence of new water in the tundra reduces the Nenets&#x2019; ability to travel by foot, sled, or motor vehicle from the summer transitory tundra campsites in order to access healthcare centers in villages. New water can also impede their access to family and community at other herder camps and in the villages. Although regional and global models predicting hydrologic changes due to climate changes exist, the spatial resolution of these models is too coarse for studying how increases in open water affect health and livelihoods. To anticipate the full health impact of hydrologic changes, the current gap between globally forecasted scenarios and locally forecasted hydrologic scenarios needs to be bridged. Objectives . We studied the effects of the autumn temperature anomalies and increases in open water on health care access and transmigration of reindeer herders on the Kanin Peninsula. Design . Correlational and time series analyses were completed. Methods . The study population consisted of 370 full-time, nomadic reindeer herders. We utilized clinical visit records, studied surface temperature anomalies during autumn migrations, and used remotely sensed imagery to detect water bodies. Spearman correlation was used to measure the relationship between temperature anomalies and the annual arrival of the herders at the Nes clinic for preventive and primary care. Piecewise regression was used to model change in mean autumnal temperature anomalies over time. We also created a water body product to detect inter-annual changes in water area. Results . Correlation between arrivals to the Nes clinic and temperature anomalies during the fall transmigration (1979&#x2013;2011) was r =&#x200A;0.64, p&#x200A;=&#x200A;0.0004; 95% CI (0.31; 0.82). Regression analysis estimated that mean temperature anomalies during the fall migration in September&#x2013;December were stochastically stationary pre-1991 and have been rising significantly (p&#x200A;&#60;&#x200A;0.001) since then. The rate of change was estimated at +0.1351&#x00B0;C/year, SE&#x200A;=&#x200A;0.0328, 95% CI (+0.0694, +0.2007). The amount of detected water fluctuated significantly interannually (620&#x2013;800 km2). Conclusions . Later arrival of freezing temperatures in the autumn followed by the earlier spring thaws and more open water delay transmigration and reduce herders&#x2019; access to health care. The recently observed delays in arrival to the clinic are likely related to the warming trend and to concomitant hydrologic changes

    Who Engaged in Home-Based Arts Activities During the COVID-19 Pandemic? A Cross-Sectional Analysis of Data From 4,731 Adults in the United States

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    Arts engagement is a health-related behavior that may be influenced by social inequalities. While the COVID-19 pandemic provided new opportunities for some people to engage in the arts, it might have created barriers for others. We aimed to examine whether there was social patterning in home-based arts engagement during the pandemic in the United States, and whether predictors of engagement differed according to the type of arts activity. We included 4,731 adults who participated in the United States COVID-19 Social Study between April and July 2020. Three types of home-based arts engagement were considered: reading for pleasure, arts or crafts activities, and digital arts activities. Using logistic regression models, we tested cross-sectional associations between a broad range of demographic, socioeconomic, psychosocial, and health-related factors as well as adverse events and worries during lockdown and each type of arts engagement. The factors most strongly associated with all three types of arts engagement were social support, social network size, age, race/ethnicity, keyworker status, and experiencing physical or psychological abuse during the pandemic. However, most socioeconomic and health-related factors were not associated with arts engagement, including household income and mental and physical health problems. Overall, our findings indicate that the social gradient in arts engagement was reduced in the first 4 months of the COVID-19 pandemic in the United States. Given the health benefits of arts engagement, the potential diversification of arts audiences during the pandemic is promising for both population-level health and wellbeing and the future of the arts and cultural sector

    MATCH: An atom‐typing toolset for molecular mechanics force fields

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    We introduce a toolset of program libraries collectively titled multipurpose atom‐typer for CHARMM (MATCH) for the automated assignment of atom types and force field parameters for molecular mechanics simulation of organic molecules. The toolset includes utilities for the conversion of multiple chemical structure file formats into a molecular graph. A general chemical pattern‐matching engine using this graph has been implemented whereby assignment of molecular mechanics atom types, charges, and force field parameters are achieved by comparison against a customizable list of chemical fragments. While initially designed to complement the CHARMM simulation package and force fields by generating the necessary input topology and atom‐type data files, MATCH can be expanded to any force field and program, and has core functionality that makes it extendable to other applications such as fragment‐based property prediction. In this work, we demonstrate the accurate construction of atomic parameters of molecules within each force field included in CHARMM36 through exhaustive cross validation studies illustrating that bond charge increment rules derived from one force field can be transferred to another. In addition, using leave‐one‐out substitution it is shown that it is also possible to substitute missing intra and intermolecular parameters with ones included in a force field to complete the parameterization of novel molecules. Finally, to demonstrate the robustness of MATCH and the coverage of chemical space offered by the recent CHARMM general force field (Vanommeslaeghe, et al., J Comput Chem 2010, 31, 671), one million molecules from the PubChem database of small molecules are typed, parameterized, and minimized. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/88100/1/JCC_21963_sm_SuppInfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/88100/2/21963_ftp.pd
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