1,068 research outputs found
Evidence of Final-State Suppression of High-p_T Hadrons in Au + Au Collisions Using d + Au Measurements at RHIC
Transverse momentum spectra of charged hadrons with 6 GeV/c have
been measured near mid-rapidity (0.2 1.4) by the PHOBOS experiment
at RHIC in Au + Au and d + Au collisions at . The spectra for different collision centralities are compared to collisions at the same energy. The resulting nuclear modification
factor for central Au + Au collisions shows evidence of strong suppression of
charged hadrons in the high- region ( GeV/c). In contrast, the d +
Au nuclear modification factor exhibits no suppression of the high-
yields. These measurements suggest a large energy loss of the high-
particles in the highly interacting medium created in the central Au + Au
collisions. The lack of suppression in d + Au collisions suggests that it is
unlikely that initial state effects can explain the suppression in the central
Au + Au collisions.Comment: 3 pages, 4 figures, International Europhysics Conference on High
Energy Physics EPS (July 17th-23rd 2003) in Aachen, German
Identified particles in Au+Au collisions at sqrt{s_NN} = 200 GeV
The yields of identified particles have been measured at RHIC for Au+Au
collisions at sqrt{s_NN} = 200 GeV using the PHOBOS spectrometer. The ratios of
antiparticle to particle yields near mid-rapidity are presented. The first
measurements of the invariant yields of charged pions, kaons and protons at
very low transverse momenta are also shown.Comment: 4 pages, 4 figures, Contribution to Quark Matter 2002, Nantes,
France, July 200
Universal Behavior of Charged Particle Production in Heavy Ion Collisions
The PHOBOS experiment at RHIC has measured the multiplicity of primary
charged particles as a function of centrality and pseudorapidity in Au+Au
collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV. Two kinds of universal
behavior are observed in charged particle production in heavy ion collisions.
The first is that forward particle production, over a range of energies,
follows a universal limiting curve with a non-trivial centrality dependence.
The second arises from comparisons with pp/pbar-p and e+e- data.
N_tot/(N_part/2) in nuclear collisions at high energy scales with sqrt(s) in a
similar way as N_tot in e+e- collisions and has a very weak centrality
dependence. This feature may be related to a reduction in the leading particle
effect due to the multiple collisions suffered per participant in heavy ion
collisions.Comment: 4 Pages, 5 Figures, contributed to the Proceedings of Quark Matter
2002, Nantes, France, 18-24 July 200
Recent Results from PHOBOS at RHIC
The PHOBOS experiment at RHIC has recorded measurements for Au-Au collisions
spanning nucleon-nucleon center-of-mass energies from 19.6 GeV to 200 GeV.
Global observables such as elliptic flow and charged particle multiplicity
provide important constraints on model predictions that characterize the state
of matter produced in these collisions. The nearly 4 pi acceptance of the
PHOBOS experiment provides excellent coverage for complete flow and
multiplicity measurements. Results including beam energy and centrality
dependencies are presented and compared to elementary systems.Comment: 4 pages, 4 figures, proceedings from PANIC02 in Osaka, Japa
Global Observations from PHOBOS
Particle production in Au+Au collisions has been measured in the PHOBOS
experiment at RHIC for a range of collision energies. Three empirical
observations have emerged from this dataset which require theoretical
examination. First, there is clear evidence of limiting fragmentation. Namely,
particle production in central Au+Au collisions, when expressed as
(), becomes energy independent at high energy for a
broad region of around . This energy-independent region grows
with energy, allowing only a limited region (if any) of longitudinal
boost-invariance. Second, there is a striking similarity between particle
production in e+e- and Au+Au collisions (scaled by the number of participating
nucleon pairs). Both the total number of produced particles and the
longitudinal distribution of produced particles are approximately the same in
e+e- and in scaled Au+Au. This observation was not predicted and has not been
explained. Finally, particle production has been found to scale approximately
with the number of participating nucleon pairs for . This scaling
occurs both for the total multiplicity and for high \pT particles (3 <\pT<
4.5 GeV/c).Comment: QM2002 plenary talk, 10 pages, 11 figure
Radio Location of Partial Discharge Sources: A Support Vector Regression Approach
Partial discharge (PD) can provide a useful forewarning of asset failure in electricity substations. A significant proportion of assets are susceptible to PD due to incipient weakness in their dielectrics. This paper examines a low cost approach for uninterrupted monitoring of PD using a network of inexpensive radio sensors to sample the spatial patterns of PD received signal strength. Machine learning techniques are proposed for localisation of PD sources. Specifically, two models based on Support Vector Machines (SVMs) are developed: Support Vector Regression (SVR) and Least-Squares Support Vector Regression (LSSVR). These models construct an explicit regression surface in a high dimensional feature space for function estimation. Their performance is compared to that of artificial neural network (ANN) models. The results show that both SVR and LSSVR methods are superior to ANNs in accuracy. LSSVR approach is particularly recommended as practical alternative for PD source localisation due to it low complexity
Effective interaction between helical bio-molecules
The effective interaction between two parallel strands of helical
bio-molecules, such as deoxyribose nucleic acids (DNA), is calculated using
computer simulations of the "primitive" model of electrolytes. In particular we
study a simple model for B-DNA incorporating explicitly its charge pattern as a
double-helix structure. The effective force and the effective torque exerted
onto the molecules depend on the central distance and on the relative
orientation. The contributions of nonlinear screening by monovalent counterions
to these forces and torques are analyzed and calculated for different salt
concentrations. As a result, we find that the sign of the force depends
sensitively on the relative orientation. For intermolecular distances smaller
than it can be both attractive and repulsive. Furthermore we report a
nonmonotonic behaviour of the effective force for increasing salt
concentration. Both features cannot be described within linear screening
theories. For large distances, on the other hand, the results agree with linear
screening theories provided the charge of the bio-molecules is suitably
renormalized.Comment: 18 pages, 18 figures included in text, 100 bibliog
Development of a patient-reported outcomes symptom measure for patients with nontransfusion-dependent thalassemia (NTDT-PRO©)
\u3b2-Thalassemia, a hereditary blood disorder caused by reduced or absent synthesis of the \u3b2-globin chain of hemoglobin, is characterized by ineffective erythropoiesis, and can manifest as nontransfusion-dependent thalassemia (NTDT) or transfusion-dependent thalassemia (TDT). Many patients with NTDT develop a wide range of serious complications that affect survival and quality of life (QoL). Patient-reported outcomes (PRO), including health-related QoL (HRQoL), are important tools for determining patient health impairment and selecting appropriate treatment. However, there are currently no disease-specific PRO tools available to assess symptoms related to chronic anemia experienced by patients with NTDT. This study aimed to develop a new, US Food and Drug Administration (FDA)-compliant PRO of chronic anemia symptoms, the NTDT-PRO\ua9 tool, for use in patients with NTDT. Participants had a median age of 36 years (range, 18-47) and 60% were female. The initial development of the NTDT-PRO tool involved concept-elicitation interviews with 25 patients from 3 centers (in Lebanon, Greece, and Canada); subsequent interview discussions and clinical input resulted in the generation of 9 items for inclusion in the draft NTDT-PRO. Following a round of cognitive interviews involving 21 patients from 2 centers (in Lebanon and Greece), 4 items (Pain, Headaches, Ability to Concentrate, and Paleness) were removed from the draft NTDT-PRO. The final NTDT-PRO comprises 6 items that measure Tiredness, Weakness, and Shortness of Breath, with or without Physical Activity. The NTDT-PRO is a new disease-specific HRQoL tool for patients with NTDT, developed using a thorough methodology based on FDA 2009 PRO development guidelines
Daratumumab, bortezomib, and dexamethasone in relapsed or refractory multiple myeloma: subgroup analysis of CASTOR based on cytogenetic risk
BACKGROUND: Multiple myeloma (MM) patients with high cytogenetic risk have poor outcomes. In CASTOR, daratumumab plus bortezomib/dexamethasone (D-Vd) prolonged progression-free survival (PFS) versus bortezomib/dexamethasone (Vd) alone and exhibited tolerability in patients with relapsed or refractory MM (RRMM). METHODS: This subgroup analysis evaluated D-Vd versus Vd in CASTOR based on cytogenetic risk, determined using fluorescence in situ hybridization and/or karyotype testing performed locally. High-risk patients had t(4;14), t(14;16), and/or del17p abnormalities. Minimal residual disease (MRD; 10-5 sensitivity threshold) was assessed via the clonoSEQ\uae assay V2.0. Of the 498 patients randomized, 40 (16%) in the D-Vd group and 35 (14%) in the Vd group were categorized as high risk. RESULTS: After a median follow-up of 40.0\u2009months, D-Vd prolonged median PFS versus Vd in patients with standard (16.6 vs 6.6\u2009months; HR, 0.26; 95% CI, 0.19-0.37; P < 0.0001) and high (12.6 vs 6.2\u2009months; HR, 0.41; 95% CI, 0.21-0.83; P = 0.0106) cytogenetic risk. D-Vd achieved deep responses, including higher rates of MRD negativity and sustained MRD negativity versus Vd, regardless of cytogenetic risk. The safety profile was consistent with the overall population of CASTOR. CONCLUSION: These updated data reinforce the effectiveness and tolerability of daratumumab-based regimens for RRMM, regardless of cytogenetic risk status. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02136134 . Registered 12 May 2014
A promising chemical series of positive allosteric modulators of the μ-opioid receptor that enhance the antinociceptive efficacy of opioids but not their adverse effects
Positive allosteric modulators (PAMs) of the μ-opioid receptor (MOR) have been proposed to exhibit therapeutic potential by maximizing the analgesic properties of clinically used opioid drugs while limiting their adverse effects or risk of overdose as a result of using lower drug doses. We herein report in vitro and in vivo characterization of two small molecules from a chemical series of MOR PAMs that exhibit: (i) MOR PAM activity and receptor subtype selectivity in vitro, (ii) a differential potentiation of the antinociceptive effect of oxycodone, morphine, and methadone in mouse models of pain that roughly correlates with in vitro activity, and (iii) a lack of potentiation of adverse effects associated with opioid administration, such as somatic withdrawal, respiratory depression, and analgesic tolerance. This series of MOR PAMs holds promise for the development of adjuncts to opioid therapy to mitigate against overdose and opioid use disorders
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