4,107 research outputs found
Studying Intermediate pT Hadron Production with Fluctuations
Mechanisms for particle production at intermediate pT in nuclear collisions
at RHIC are discussed, emphasizing the differences in associated jet-like
correlations between color-neutral and colored production. An alternative
production mechanism involving both recombination and fragmentation is
suggested, which might simultaneously lead to an enhancement of baryons and to
jet-like correlations. To gain more insight into the relative importance of
different mechanisms a study of constrained distributions of associated
multiplicity is proposed. In a simple model it is shown that these multiplicity
distributions may change significantly, if the nature of the production
mechanism fluctuates from event to event.Comment: 7 pages, 4 figures, talk at Hot Quarks 2004 conferenc
Baryon deceleration by strong chromofields in ultrarelativistic nuclear collisions
It is assumed that strong chromofields are generated at early stages of
ultrarelativistic heavy-ion collisions which give rise to a collective
deceleration of net baryons from colliding nuclei. We have solved classical
equations of motion for baryonic slabs under the action of a time-dependent
longitudinal chromoelectric field. It is demonstrated that the slab final
rapidities are rather sensitive to the strength and decay time of the
chromofield as well as to the back reaction of the produced partonic plasma.
The net-baryon rapidity loss of about 2 units, found for most central Au-Au
collisions at RHIC, can be explained by the action of chromofields with the
initial energy density of about 50 GeV/fm^3. Predictions for the baryon
stopping at the LHC are made.Comment: 10 pages in revtex, 3 eps figure
Markierungsversuche und Modellierung zur Bewertung der Gefährdung eines Trinkwasserbrunnens
Kurzfassung: In einem Porengrundwasserleiter aus Niederterrassenschottern bei Pratteln, Schweiz, wurde ein Markierungsversuch mit Uranin durchgeführt, um die Gefährdung eines Trinkwasserbrunnens durch ein 760 m talaufwärts gelegenen Ablagerungsstandort zu bewerten. Dabei wurde eine maximale Abstandsgeschwindigkeit von 127 m/d und ein Wiedererhalt von 0,93 % festgestellt. Der Tracer wurde auch in zwei intermediären Beobachtungsbrunnen nachgewiesen. Diese Studie diskutiert die Ursachen dieser hohen Fließgeschwindigkeit. Durch drei verschiedene analytische Modelle konnten die Durchgangskurven simuliert und Transportparameter bestimmt werden. Erst die Anwendung eines zweidimensionalen numerischen Modells (FEFLOW) mit vereinfachter Geometrie liefert aber eine hydrogeologisch konsistente, mögliche Erklärung aller Versuchsergebnisse. Demnach handelt es sich vermutlich um einen relativ homogenen Grundwasserleiter. Der steile Gradient (6 ‰) und die hohe Durchlässigkeit (3 · 10-2 m/s) verursachen die hohen Fließgeschwindigkeiten. Der Hauptteil der Tracerwolke strömt seitlich an den Brunnen vorbei. Durch später durchgeführte Kleinpumpversuche wurde diese Modellvorstellung weitgehend bestätigt. Diese Befunde sollten bei Schutz- und Sanierungskonzepten berücksichtigt werde
Long-Term Effectiveness of Radar Speed Display Signs in a University Environment
Vehicular speeds are of particular interest in areas with a high number of pedestrians due to the fact that 14-percent of all fatal crashes involve pedestrians. This study investigated the effect of a radar speed display sign placed for an extended period of time, at a location frequented by law enforcement on a road segment entering a university campus with a high number of pedestrians and vehicle speed violations. The statistical analysis included a comparison between AM peak, PM peak, and midday speeds collected one year apart. The data suggested that radar speed display signs can remain effective over a long period of time; causing drivers to decelerate when warned of a speeding violation. While other studies have examined long-term impacts of similar technologies, none have included a road entering a University campus. Thus, these findings support that other similar locations entering university campuses could see long-term benefits to stationary radar speed display signs
Resonance decay effects on anisotropy parameters
We present the elliptic flow of pions produced from resonance decays.
The transverse momentum spectra of the parent particles are taken from
thermal model fits and their are fit under the assumption that they
follow number-of-constituent-quark (NCQ) scaling expected from
quark-coalescence models. The of pions from resonance particle decays is
found to be similar to the measured pion . We also propose the measurement
of electron as a means to extract open-charm and investigate
whether a thermalized system of quarks and gluons (a quark-gluon plasma) is
created in collisions of Au nuclei at RHIC.Comment: 5 pages, 4 figure
Streptococcus suis in German pig holdings—conventional and molecular detection
Streptococcus suis (S. suis) is a zoonotic agent worldwide. Pigs are the main reservoir, mostly asymptomatic. Humans get the infection by contact and consumption of contaminated meat and meat products. In this study, samples from 38 pig carcasses fit for human consumption from 17 holdings were arbitrarily selected. From each carcass, seven tissue samples were taken and examined for the presence of S. suis, using conventional microbiology and PCR. In addition, virulence-associated factors (epf, arcA, sly, mrp) were tested with PCR. More isolates were PCR-positive for S. suis as compared to conventional testing, mostly in samples from the heart and from the mandibular lymphnodes. All isolates were epf negative, combinations of arcA, sly and mrp were found in some isolates. Six isolates were positive for arcA and mrp, five for arcA and sly. For three isolates the triple combination arcA + mrp + sly was found. These isolates originated from different pigs
How Student Written Communication Skills Benefit During Participation in an Industry-Sponsored Civil Engineering Capstone Course
Because many engineering programs use capstone design courses and value strong communication abilities, authors sought to identify how student written communication skills changed because of industry-sponsored capstone design projects. A student exit survey was collected at the end of the capstone design course during faculty-led projects and projects led by practicing engineers in industry. These results led the researchers to subsequently evaluate two semesters of before-andafter writing samples using a rubric. Student surveys suggested a statistically significant increase in learning about professional issues, problem solving, and written/oral communication. Evaluation of student writing samples suggests that the students significantly improved their grammar/spelling and their organization of content during the course. These findings suggest that industry-sponsored projects help students recognize the relation between professionalism and correspondence that is organized and void of grammar and spelling errors
High Energy Nuclear Collisions: Theory Overview
We review some basic concepts of Relativistic Heavy Ion Physics and discuss
our understanding of some key results from the experimental program at the
Relativistic Heavy Ion Collider (RHIC). We focus in particular on the early
time dynamics of nuclear collisions, some result from lattice QCD, hard probes
and photons.Comment: 11 pages, 3 figures; delivered at ISNP 2009, published in Praman
Prospects for strangeness measurement in ALICE
The study of strangeness production at LHC will bring significant information
on the bulk chemical properties, its dynamics and the hadronisation mechanisms
involved at these energies. The ALICE experiment will measure strange particles
from topology (secondary vertices) and from resonance decays over a wide range
in transverse momentum and shed light on this new QCD regime. These motivations
will be presented as well as the identification performance of ALICE for
strange hadrons.Comment: 12 pages, 11 figures Proceedings of the Workshop on Relativistic
Nuclear Physics (WRNP) 2007, Kiev, Ukraine Conference Info:
http://wrnp2007.bitp.kiev.ua/ Submitted to "Physics of Atomic Nuclei
Identifying the Safety Impact of Signal Coordination Projects along Urban Arterials Using a Meta-analysis Method
The safety impact of changes to roadway operations have been of interests in recent years with the publication of the Highway Safety Manual. One area that is in need of further study is the safety impact of traffic signal coordination projects in urban areas. Specifically, this study seeks to identify the safety benefit from traffic signal coordination projects on major arterial roadways through urban areas using a before and after study with a comparison groups approach and a meta-analysis method. The findings suggest that traffic signal coordination could decrease total crashes by 21 percent, injury crashes by 52 percent and property-damage-only crashes by 21 percent. The results can be utilized by engineering practitioners to estimate the safety benefits for projects that seek to coordinate traffic signals along an urban corridor. Because these projects can both improve the safety of roadways while improving traffic flow, the application of these findings could be broad
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