On the Compact Muon Solenoid (CMS) experiment for Large Hadron Collider (LHC) at CERN laboratory, the drift tube chambers are responsible for muon detection and precise momentum measurement. In this ...paper the first level of the read out electronics for these drift tube chambers is described. These drift tube chambers will be located inside the muon barrel detector in the so-called minicrates (MCs), attached to the chambers. The read out boards (ROBs) are the main component of this first level data acquisition system, and they are responsible for the time digitalization related to Level 1 Accept (L1A) trigger of the incoming signals from the front-end electronics, followed by a consequent data merging to the next stages of the data acquisition system. ROBs' architecture and functionality have been exhaustively tested, as well as their capability of operation beyond the expected environmental conditions inside the CMS detector. Due to the satisfactory results obtained, final production of ROBs and their assembly in the MCs has already started. A total amount of 250 MCs and approximately 1500 ROBs are being produced and tested thoroughly at CIEMAT (Spain). One set of tests, the burn-in tests, will guarantee ten years of limited maintenance operation. An overview of the system and a summary of the different results of the tests performed on ROBs and MCs will be presented. They include acceptance tests for the production chain as well as several validation tests that insure proper operation of the ROBs beyond the CMS detector conditions.
The impact of mild head injury or mild traumatic brain injury (TBI) in children is variable, and determinants of outcome remain poorly understood. There have been no previous attempts to evaluate the ...impact of interventions to improve outcome. Results of previous intervention studies in adults have been mixed. This study aimed to evaluate the impact of providing information on outcome measured in terms of reported symptoms, cognitive performance, and psychological adjustment in children 3 months after injury.
A total of 61 children with mild TBI were assessed 1 week and 3 months after injury, and 58 children with mild TBI were assessed 3 months after injury only. They were compared with 2 control groups (N = 45 and 47) of children with minor injuries not involving the head. Participants completed measures of preinjury behavior and psychological adjustment, postconcussion symptoms, and tests of attention, speed of information processing, and memory. Children with mild TBI seen at 1 week were also given an information booklet outlining symptoms associated with mild TBI and suggested coping strategies. Those seen 3 months after injury only did not receive this booklet.
Children with mild TBI reported more symptoms than controls at 1 week but demonstrated no impairment on neuropsychological measures. Initial symptoms had resolved for most children by 3 months after injury, but a small group of children who had previous head injury or a history of learning or behavioral difficulties reported ongoing problems. The group not seen at 1 week and not given the information booklet reported more symptoms overall and was more stressed 3 months after injury.
Providing an information booklet reduces anxiety and thereby lowers the incidence of ongoing problems.
We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. Previous results have demonstrated that our detector concept, based on monolithic ...scintillator crystals coupled to magnetically-compatible APD matrices with a dedicated ASIC front-end, is suitable for this application. In this work we present the final design of our PET scanner and report on the characterization of a prototype demonstrator used to validate the coincidence processing and data readout architecture.
Mimicry is one of the best-studied examples of adaptation, and recent studies have provided new insights into the role of mimicry in speciation and diversification. Classical Müllerian mimicry theory ...predicts convergence in warning signal among protected species, yet tropical butterflies are exuberantly diverse in warning colour patterns, even within communities. We tested the hypothesis that microhabitat partitioning in aposematic butterflies and insectivorous birds can lead to selection for different colour patterns in different microhabitats and thus help maintain mimicry diversity. We measured distribution across flight height and topography for 64 species of clearwing butterflies (Ithomiini) and their co-mimics, and 127 species of insectivorous birds, in an Amazon rainforest community. For the majority of bird species, estimated encounter rates were non-random for the two most abundant mimicry rings. Furthermore, most butterfly species in these two mimicry rings displayed the warning colour pattern predicted to be optimal for antipredator defence in their preferred microhabitats. These conclusions were supported by a field trial using butterfly specimens, which showed significantly different predation rates on colour patterns in two microhabitats. We therefore provide the first direct evidence to support the hypothesis that different mimicry patterns can represent stable, community-level adaptations to differing biotic environments.
Spatial and temporal sampling errors inherent in large‐ scale, weather‐station (raingauge) climatologies of precipitation are evaluated. A primary goal is to assess whether more representative ...large‐scale precipi‐ tation climatologies emerge when (i) more station means are included, even when they are based on unequal periods of record, or (ii) fewer station means are included but all are derived from the same period of record. Observations drawn from the Historical Climatology Network (HCN) are used to estimate temporally averaged precipitation over 10‐, 20‐, and 30‐year intervals at 457 stations within the USA. Two strategies for estimating these ‘observed’ means are examined, one based on temporal ‘substitution’ within each station record, and the other based on spatial interpolation from surrounding stations. Temporally estimated m‐year means were obtained by substituting other m‐year means, from within the same station record, for each ‘observed’ m‐year mean, where m is the length of the averaging period of interest. Spatially interpolated m‐year means were estimated from m‐year means associated with nearby stations.
Climatologies containing a greater number of station averages, even if they are computed over unequal averaging periods, appear to better represent the space–time variability in mean precipitation than climatologies containing fewer, but temporally commensurate, station means. Our results (for precipitation‐station networks on the order of 50–60 stations per 106 km2) indicate that the within‐station‐ record substitution of means is about 1ċ3 to 2ċ5 times more accurate than is interpolation from surrounding station means. Within‐station substitu tion errors—associated with estimating any 10‐year mean precipitation from any other 10‐year mean—for example, were about 8 per cent of the long‐term spatial precipitation mean for the USA, or 67ċ6 mm. Spatially interpolated 10‐year means, from nearby stations, were in error by more than 10 per cent, or 88ċ8 mm on average.
Much of the space–time variability in mean precipitation was not resolved adequately by the 457 HCN stations, especially high‐frequency spatial variability caused by orographic and convective mechanisms. For many regions of the world, temporally homogeneous precipitation station networks are considerably more sparse than in the USA, further degrading the reliability of interpolated and spatially integrated mean precipitation fields derived solely from those networks.
Water balance calculations are becoming increasingly important for earth-system studies. Precipitation is one of the most critical input variables for such calculations because it is the immediate ...source of water for the land surface hydrological budget. Numerous precipitation datasets have been developed in the last two decades, but these datasets often show marked differences in their spatial and temporal distribution of this key hydrological variable. This paper compares six monthly precipitation datasets—Climate Research Unit of University of East Anglia (CRU), Willmott–Matsuura (WM), Global Precipitation Climate Center (GPCC), Global Precipitation Climatology Project (GPCP), Tropical Rainfall Measuring Mission (TRMM), and NCEP–Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (NCEP-2)—to assess the uncertainties in these datasets and their impact on the terrestrial water balance. The six datasets tested in the present paper were climatologically averaged and compared by calculating various statistics of the differences. The climatologically averaged monthly precipitation estimates were applied as inputs to a water balance model to estimate runoff and the uncertainties in runoff arising directly from the precipitation estimates. The results of this study highlight the need for accurate precipitation inputs for water balance calculations. These results also demonstrate the need to improve precipitation estimates in arid and semiarid regions, where slight changes in precipitation can result in dramatic changes in the runoff response due to the nonlinearity of the runoff-generation processes.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We evaluate two approaches to spatially interpolating winter surface air-temperature fields over the terrestrial Arctic from available weather-station records. We then examine 30 yr (1961–1990) of ...winter air-temperature change over the terrestrial Arctic through a time-trend analysis of interpolated winter air-temperature fields. We used monthly average air temperatures from 4984 Arctic station records that were available for the period 1961–1990. The two spatial interpolation procedures employed were “traditional” interpolation and a method that makes use of spatially high-resolution digital-elevation information, called “DEM-assisted” (DAI). The Arctic average winter air temperature obtained from the traditionally interpolated 1961–1990 climatology is over 9°C colder than the mean winter station temperature, illustrating the considerable warm bias in Arctic weather station locations. The DAI-based average is 1°C colder, further emphasizing the importance of spatial interpolation prior to spatial averaging. Over the 30 yr, increases in winter air temperature appear across western Canada and in parts of central Asia, with decreasing trends apparent over eastern Canada. Much of the Arctic exhibits no clear trend, with low explained variances. In western Canada, however, warming trends are on the order of 0.1 to 0.4°C yr−1 when the fields analyzed were traditionally interpolated or interpolated using DAI. Explained variances (r2s) are higher where trends are largest: approximately 0.2 to 0.4 in western Canada and slightly higher (albeit spuriously) in an isolated area of central Asia. Over the entire terrestrial Arctic, mean winter air temperature has increased at a rate of about 0.05°C yr−1 based on traditional interpolation and DAI.
Statistics for the evaluation and comparison of models Willmott, Cort J.; Ackleson, Steven G.; Davis, Robert E. ...
Journal of Geophysical Research: Oceans,
20 September 1985, Letnik:
90, Številka:
C5
Journal Article
Recenzirano
Odprti dostop
Procedures that may be used to evaluate the operational performance of a wide spectrum of geophysical models are introduced. Primarily using a complementary set of difference measures, both model ...accuracy and precision can be meaningfully estimated, regardless of whether the model predictions are manifested as scalars, directions, or vectors. It is additionally suggested that the reliability of the accuracy and precision measures can be determined from bootstrap estimates of confidence and significance. Recommended procedures are illustrated with a comparative evaluation of two models that estimate wind velocity over the South Atlantic Bight.
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