| 1. |
- Adler, S. S., et al.
(författare)
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Jet structure from dihadron correlations in d+Au collisions at root S-NN=200 GeV
- 2006
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 73:5
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Tidskriftsartikel (refereegranskat)abstract
- Dihadron correlations at high transverse momentum p(T) in d+Au collisions at root s(NN)=200 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. From these correlations, we extract several structural characteristics of jets: the root-mean-squared transverse momentum of fragmenting hadrons with respect to the jet root < j(T)(2)>, the mean sine-squared of the azimuthal angle between the jet axes < sin(2)phi(jj)>, and the number of particles produced within the dijet that are associated with a high-p(T) particle (dN/dx(E) distributions). We observe that the fragmentation characteristics of jets in d+Au collisions are very similar to those in p+p collisions and that there is little dependence on the centrality of the d+Au collision. This is consistent with the nuclear medium having little influence on the fragmentation process. Furthermore, there is no statistically significant increase in the value of < sin(2)phi(jj)> from p+p to d+Au collisions. This constrains the effect of multiple scattering that partons undergo in the cold nuclear medium before and after a hard collision.
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| 2. |
- Adler, S. S., et al.
(författare)
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Nuclear effects on hadron production in d plus Au collisions at root S-NN=200 GeV revealed by comparison with p plus p data
- 2006
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 74:2
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Tidskriftsartikel (refereegranskat)abstract
- PHENIX has measured the centrality dependence of midrapidity pion, kaon, and proton transverse momentum distributions in d+Au and p+p collisions at root s(NN) = 200 GeV. The p+p data provide a reference for nuclear effects in d+Au and previously measured Au+Au collisions. Hadron production is enhanced in d+Au, relative to independent nucleon-nucleon scattering, as was observed in lower energy collisions. The nuclear modification factor for (anti)protons is larger than that for pions. The difference increases with centrality but is not sufficient to account for the abundance of baryon production observed in central Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). The centrality dependence in d+Au shows that the nuclear modification factor increases gradually with the number of collisions encountered by each participant nucleon. We also present comparisons with lower energy data as well as with parton recombination and other theoretical models of nuclear effects on particle production.
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| 3. |
- Adler, S. S., et al.
(författare)
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Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at root(NN)-N-S=200 GeV
- 2006
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Ingår i: Physical Review Letters. - 1079-7114. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at root s(NN)=200 GeV. The distribution of jet-associated partner hadrons (1.0 < p(T)< 2.5 GeV/c) per trigger hadron (2.5 < p(T)< 4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.
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| 4. |
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| 5. |
- Adler, SS, et al.
(författare)
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Single electrons from heavy-flavor decays in p + p collisions at root s=200 GeV
- 2006
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Ingår i: Physical Review Letters. - 1079-7114. ; 96:3
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Tidskriftsartikel (refereegranskat)abstract
- The invariant differential cross section for inclusive electron production in p+p collisions at root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4 <= p(T) <= 5.0 GeV/c in the central rapidity region (vertical bar eta vertical bar <= 0.35). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e., charm quarks or, at high p(T), bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy-flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be sigma(c (c) over bar) = 0.92 +/- 0.15(stat) +/- 0.54(syst) mb.
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| 6. |
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| 7. |
- Hensiek, A E, et al.
(författare)
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Familial effects on the clinical course of multiple sclerosis.
- 2007
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 1526-632X .- 0028-3878. ; 68:5, s. 376-83
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Familial factors influence susceptibility to multiple sclerosis (MS) but it is unknown whether there are additional effects on the natural history of the disease. METHOD: We evaluated 1,083 families with > or =2 first-degree relatives with MS for concordance of age at onset, clinical course, and disease severity and investigated transmission patterns of these clinical features in affected parent-child pairs. RESULTS: There is concordance for age at onset for all families (correlation coefficient 0.14; p < 0.001), as well as for affected siblings (correlation coefficient 0.15; p < 0.001), and affected parent-child pairs (correlation coefficient 0.12; p = 0.03) when each is evaluated separately. Concordance for year of onset is present among affected siblings (correlation coefficient 0.18; p < 0.001) but not the parent-child group (correlation coefficient 0.08; p = 0.15). The clinical course is similar between siblings (kappa 0.12; p < 0.001) but not affected parents and their children (kappa -0.04; p = 0.09). This influence on the natural history is present in all clinical subgroups of relapsing-remitting, and primary and secondary progressive MS, reflecting a familial effect on episodic and progressive phases of the disease. There is no concordance for disease severity within any of the considered family groups (correlation coefficients: all families analyzed together, 0.02, p = 0.53; affected sibling group, 0.02, p = 0.61; affected parent-child group, 0.02, p = 0.69). Furthermore, there are no apparent transmission patterns of any of the investigated clinical features in affected parent-child pairs and no evidence for anticipation or effects of genetic loading. CONCLUSION: Familial factors do not significantly affect eventual disease severity. However, they increase the probability of a progressive clinical course, either from onset or after a phase of relapsing remitting disease. The familial effect is more likely to reflect genetic than environmental conditions. The results are relevant for counseling patients and have implications for the design of studies seeking to identify factors that influence the natural history of the disease.
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| 8. |
- Gray, L J, et al.
(författare)
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Significant variation in mortality and functional outcome after acute ischaemic stroke between western countries : Data from the tinzaparin in acute ischaemic stroke trial (TAIST)
- 2006
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Ingår i: Journal of Neurology, Neurosurgery and Psychiatry. - : BMJ. - 0022-3050 .- 1468-330X. ; 77:3, s. 327-333
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Tidskriftsartikel (refereegranskat)abstract
- Background: The medical care of patients with acute stroke varies considerably between countries. This could lead to measurable differences in mortality and functional outcome. Objective: To compare case mix, clinical management, and functional outcome in stroke between 11 countries. Methods: All 1484 patients from 11 countries who were enrolled into the tinzaparin in acute ischaemic stroke trial (TAIST) were included in this substudy. Information collected prospectively on demographics, risk factors, clinical features, measures of service quality (for example, admission to a stroke unit), and outcome were assessed. Outcomes were adjusted for treatment assignment, case mix, and service relative to the British Isles. Results: Differences in case mix (mostly minor) and clinical service (many of prognostic relevance) were present between the countries. Significant differences in outcome were present between the countries. When assessed by geographical region, death or dependency were lower in North America (odds ratio (OR) adjusted for treatment group only = 0.52 (95% confidence interval, 0.39 to 0.71) and north west Europe (OR = 0.54 (0.37 to 0.78)) relative to the British Isles, similar reductions were found when adjustments were made for 11 case mix variables and five service quality measures. Similarly, case fatality rates were lower in North America (OR = 0.44 (0.30 to 0.66)) and Scandinavia (OR = 0.50 (0.33 to 0.74)) relative to the British Isles, whether crude or adjusted for case mix and service quality. Conclusions: Both functional outcome and case fatality vary considerably between countries, even when adjusted for prognostic case mix variables and measures of good stroke care. Differing health care systems and the management of patients with acute stroke may contribute to these findings.
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