2,705 research outputs found
Thermal photon production in high-energy nuclear collisions
We use a boost-invariant one-dimensional (cylindrically symmetric) fluid
dynamics code to calculate thermal photon production in the central rapidity
region of S+Au and Pb+Pb collisions at SPS energy ( GeV/nucleon).
We assume that the hot matter is in thermal equilibrium throughout the
expansion, but consider deviations from chemical equilibrium in the high
temperature (deconfined) phase. We use equations of state with a first-order
phase transition between a massless pion gas and quark gluon plasma, with
transition temperatures in the range MeV.Comment: revised, now includes a_1 contribution. revtex, 10 pages plus 4
figures (uuencoded postscript
Measuring by marking; the multimedia annotation tool ELAN
ELAN is a multimedia annotation tool developed by the Max Planck Institute for Psycholinguistics. It is applied in a variety of research areas. This paper presents a general overview of the tool and new developments as the calculation of inter-rater reliability, a commentary framework, semi-automatic segmentation and labeling and export to Theme
Mortality of Vertebrates and Invertebrates on an Athens County, Ohio, Highway
Author Institution: Department of Zoological and Biomedical Sciences, Ohio UniversityAlthough previous road-kill surveys have tallied the number and kinds of vertebrates that were victims of vehicular traffic (mostly birds and mammals), none has recorded invertebrate mortality. A 14-month survey on foot of each side of a 1.6 km (1 mi) stretch of dual lane highway provided 188 vertebrate and 1,162 invertebrate victims. Finding rare and unusual species of invertebrates suggests that this technique be used as a supplementary faunal survey
Advancement in the multimedia annotation tool ELAN
ELAN is a multimedia annotation tool that is being developed by the Max Planck Institute for Psycholinguistics. It is a tool that is applied in various types of multimodal interaction research. This poster presents the most recent achievements in what by now is a long history of continuous tool development and support. New developments are assessment of inter-rater reliability, a commentary framework and export to Theme format
Biaxial Testing of Elastomers: Experimental Setup, Measurement and Experimental Optimisation of Specimenâs Shape
The present article deals with the setup and the control of a biaxial tension test device for characterising the material properties of elastomers. After a short introduction into the experimental setup a brief explanation of the benefits of a biaxial tension test is given. Furthermore the analysis of this test will be discussed. Therefore, the used optical field measurement by digital image correlation for analysing the strains is shortly introduced to the reader. Additionally, the basic concepts of the calculation of an inverse boundary problem for identifying the materialâs parameters are imposed. However the main focus is laid on the experimental optimisation of the specimenâs geometry, whereupon a nearly hyperelastic, incompressible silicone is used to get the experimental results. The resulting geometry will be specially fitted to the requirements of elastomers. The tested geometries and the evaluation of the experiments will be explained as well as the resulting quality factor for the suitability of a specimenâs shape. After all, a short validation of the foregoing considerations will be presented
Self-guided smartphone excursions in university teachingâexperiences from exploring âWater in the Cityâ
Like many other university teachers, we were faced with an unprecedented situation in spring 2020, when we had to cancel on-site teaching and excursions due to the Covid-19 pandemic. However, we were in the fortunate position that we had already started to develop a smartphone-based self-guided excursion on the topic of âWater in the Cityâ. We accelerated this development and used it to replace the traditional group excursion in our Bachelor level introductory course in Hydrology and Climatology. The excursion of this course is visited by around 150 students each year. Because the student feedback was overall very positive, we used the self-guided excursion again in 2021 and plan to continue to use it in the coming years. In this paper, we describe the excursion, discuss the experiences of the students and ourselves, and present recommendations and ideas that could be useful for similar excursions at other universities
The Calibration of the WISE W1 and W2 Tully-Fisher Relation
In order to explore local large-scale structures and velocity fields,
accurate galaxy distance measures are needed. We now extend the well-tested
recipe for calibrating the correlation between galaxy rotation rates and
luminosities -- capable of providing such distance measures -- to the all-sky,
space-based imaging data from the Wide-field Infrared Survey Explorer (WISE) W1
(m) and W2 (m) filters. We find a linewidth to absolute
magnitude correlation (known as the Tully-Fisher Relation, TFR) of
(0.54
magnitudes rms) and (0.56 magnitudes rms) from 310 galaxies in 13 clusters. We update the
I-band TFR using a sample 9% larger than in Tully & Courtois (2012). We derive
(0.46 magnitudes
rms). The WISE TFRs show evidence of curvature. Quadratic fits give
(0.52 magnitudes rms) and (0.55
magnitudes rms). We apply an I-band -- WISE color correction to lower the
scatter and derive
and (both 0.46
magnitudes rms). Using our three independent TFRs (W1 curved, W2 curved and
I-band), we calibrate the UNION2 supernova Type Ia sample distance scale and
derive (stat) (sys) kms Mpc with 4%
total error.Comment: 22 page, 21 figures, accepted to ApJ, Table 1 data at
http://spartan.srl.caltech.edu/~neill/tfwisecal/table1.tx
Accuracy of crowdsourced streamflow and stream level class estimates
Streamflow data are important for river management and the calibration of hydrological models. However, such data are only available for gauged catchments. Citizen science offers an alternative data source, and can be used to estimate streamflow at ungauged sites. We evaluated the accuracy of crowdsourced streamflow estimates for 10 streams in Switzerland by asking citizens to estimate streamflow either directly, or based on the estimated width, depth and velocity of the stream. Additionally, we asked them to estimate the stream level class by comparing the current stream level with a picture that included a virtual staff gauge. To compare the different estimates, the stream level class estimates were converted into streamflow. The results indicate that stream level classes were estimated more accurately than streamflow, and more accurately represented high and low flow conditions. Based on this result, we suggest that citizen science projects focus on stream level class estimates instead of streamflow estimates
Value of crowdâbased water level class observations for hydrological model calibration
While hydrological models generally rely on continuous streamflow data for calibration, previous studies have shown that a few measurements can be sufficient to constrain model parameters. Other studies have shown that continuous water level or water level class (WLâclass) data can be informative for model calibration. In this study, we combined these approaches and explored the potential value of a limited number of WLâclass observations for calibration of a bucketâtype runoff model (HBV) for four catchments in Switzerland. We generated synthetic data to represent citizen science data and examined the effects of the temporal resolution of the observations, the numbers of WLâclasses, and the magnitude of the errors in the WLâclass data on the model validation performance. Our results indicate that on average one observation per week for a oneâyear period can significantly improve model performance compared to the situation without any streamflow data. Furthermore, the validation performance for model parameters calibrated with WLâclass observations was similar to the performance of the calibration with precise water level measurements. The number of WLâclasses did not influence the validation performance noticeably when at least four WLâclasses were used. The impact of typical errors for citizenâscienceâbased estimates of WLâclasses on the model performance was small. These results are encouraging for citizen science projects where citizens observe water levels for otherwise ungauged streams using virtual or physical staff gauges
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