532 research outputs found
A systematic study of J/psi suppression in cold nuclear matter
Based on a Glauber model, a statistical analysis of all mid-rapidity J/psi
hadroproduction and leptoproduction data on nuclear targets is carried out.
This allows us to determine the J/psi-nucleon inelastic cross section, whose
knowledge is crucial to interpret the J/psi suppression observed in heavy-ion
collisions, at SPS and at RHIC. The values of sigma are extracted from each
experiment. A clear tension between the different data sets is reported. The
global fit of all data gives sigma=3.4+/-0.2 mb, which is significantly smaller
than previous estimates. A similar value, sigma=3.5+/-0.2 mb, is obtained when
the nDS nuclear parton densities are included in the analysis, although we
emphasize that the present uncertainties on gluon (anti)shadowing do not allow
for a precise determination of sigma. Finally, no significant energy dependence
of the J/psi-N interaction is observed, unless strong nuclear modifications of
the parton densities are assumed.Comment: 25 pages, 5 figure
Feasibility randomised controlled trial of a guided workbook intervention to support work-related goals among cancer survivors in the UK
Objectives: Employment following illness is associated with better physical and psychological functioning. This study aimed to assess the feasibility and acceptability of a theoretically led workbook intervention designed to support patients with cancer returning to work.
Design: Parallel-group randomised controlled trial with embedded qualitative interviews.
Setting: Oncology clinics within four English National Health Service Trusts.
Participants: Patients who had received a diagnosis of breast, gynaecological, prostate or colorectal cancer and who had been receiving treatment for a minimum of two weeks.
Intervention: A self-guided WorkPlan workbook designed to support patients with cancer to return to work with fortnightly telephone support calls to discuss progress. The control group received treatment as usual and was offered the workbook at the end of their 12-month follow-up.
Outcome measures: We assessed aspects of feasibility including eligibility, recruitment, data collection, attrition, feasibility of the methodology, acceptability of the intervention and potential to calculate cost-effectiveness.
Results: The recruitment rate of eligible patients was 44%; 68 participants consented and 58 (85%) completed baseline measures. Randomisation procedures were acceptable, data collection methods (including cost-effectiveness data) were feasible and the intervention was acceptable to participants. Retention rates at 6-month and 12-month follow-up were 72% and 69%, respectively. At 6-month follow-up, 30% of the usual care group had returned to full-time or part-time work (including phased return to work) compared with 43% of the intervention group. At 12âmonths, the percentages were 47% (usual care) and 68% (intervention).
Conclusions: The findings confirm the feasibility of a definitive trial, although further consideration needs to be given to increasing the participation rates among men and black and ethnic minority patients diagnosed with cancer
A feasibility randomized controlled trial of a guided workbook intervention to support work-related goals among cancer survivors in the UK
Objectives: Employment following illness is associated with better physical and psychological functioning. This study aimed to assess the feasibility and acceptability of a theoretically-led workbook intervention designed to support cancer patients returning to work.
Design: Parallel-group randomized controlled trial with embedded qualitative interviews
Setting: Oncology clinics within four English National Health Service Trusts
Participants: Patients who had received a diagnosis of breast, gynecological, prostate or colorectal cancer and who were at least 2 weeks post-treatment initiation.
Intervention: A self-guided WorkPlan workbook designed to support cancer patients to return to work with fortnightly telephone support calls to discuss progress. The control group received treatment as usual, and were offered the workbook at the end of their 12-month follow-up.
Outcome measures: We assessed aspects of feasibility including eligibility, recruitment, data collection, attrition, feasibility of the methodology, acceptability of the intervention and potential to calculate cost-effectiveness.
Results: The recruitment rate of eligible patients was 44%; 68 participants consented and 58 (85%) completed baseline measures. Randomization procedures were acceptable, data collection methods (including cost-effectiveness data) were feasible and the intervention was acceptable to participants. Retention rates at six and 12 months follow-up were 72% and 69% respectively. At 6-month follow-up 30% of the usual care group had returned to full or part-time work (including phased return to work) compared to 43% of the intervention group. At 12-months the percentages were 47% (usual care) and 68% (intervention).
Conclusions: The findings confirm the feasibility of a definitive trial, although further consideration needs to be given to increasing the participation rates among men and Black and ethnic minority patients diagnosed with cancer
Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller
As for all low-thrust spacecraft, finding optimal solar sailcraft trajectories is a difficult and time-consuming task that involves a lot of experience and expert knowledge, since the convergence behavior of optimizers that are based on numerical optimal control methods depends strongly on an adequate initial guess, which is often hard to find. Even if the op-timizer converges to an âoptimal trajectoryâ, this trajectory is typically close to the initial guess that is rarely close to the global optimum. This paper demonstrates, that artificial neural networks in combination with evolutionary algorithms can be applied successfully for optimal solar sailcraft steering. Since these evolutionary neurocontrollers explore the trajectory search space more exhaustively than a human expert can do by using tradi-tional optimal control methods, they are able to find steering strategies that generate better trajectories, which are closer to the global optimum. Results are presented for a Near Earth Asteroid rendezvous mission and for a Mercury rendezvous mission
Temporin L and aurein 2.5 have identical conformations but subtly distinct membrane and antibacterial activities
Frogs such as Rana temporaria and Litoria aurea secrete numerous closely related antimicrobial peptides (AMPs) as an effective chemical dermal defence. Damage or penetration of the bacterial plasma membrane is considered essential for AMP activity and such properties are commonly ascribed to their ability to form secondary amphipathic, α-helix conformations in membrane mimicking milieu. Nevertheless, despite the high similarity in physical properties and preference for adopting such conformations, the spectrum of activity and potency of AMPs often varies considerably. Hence distinguishing apparently similar AMPs according to their behaviour in, and effects on, model membranes will inform understanding of primary-sequence-specific antimicrobial mechanisms. Here we use a combination of molecular dynamics simulations, circular dichroism and patch-clamp to investigate the basis for differing anti-bacterial activities in representative AMPs from each species; temporin L and aurein 2.5. Despite adopting near identical, α-helix conformations in the steady-state in a variety of membrane models, these two AMPs can be distinguished both in vitro and in silico based on their dynamic interactions with model membranes, notably their differing conformational flexibility at the N-terminus, ability to form higher order aggregates and the characteristics of induced ion conductance. Taken together, these differences provide an explanation of the greater potency and broader antibacterial spectrum of activity of temporin L over aurein 2.5. Consequently, while the secondary amphipathic, α-helix conformation is a key determinant of the ability of a cationic AMP to penetrate and disrupt the bacterial plasma membrane, the exact mechanism, potency and spectrum of activity is determined by precise structural and dynamic contributions from specific residues in each AMP sequence
Star Formation and Dynamics in the Galactic Centre
The centre of our Galaxy is one of the most studied and yet enigmatic places
in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre
(GC) is the ideal environment to study the extreme processes that take place in
the vicinity of a supermassive black hole (SMBH). Despite the hostile
environment, several tens of early-type stars populate the central parsec of
our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and
inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the
SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The
formation of such early-type stars has been a puzzle for a long time: molecular
clouds should be tidally disrupted by the SMBH before they can fragment into
stars. We review the main scenarios proposed to explain the formation and the
dynamical evolution of the early-type stars in the GC. In particular, we
discuss the most popular in situ scenarios (accretion disc fragmentation and
molecular cloud disruption) and migration scenarios (star cluster inspiral and
Hills mechanism). We focus on the most pressing challenges that must be faced
to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in
expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A.,
'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
The âtwo-week waitâ referral pathway allows prompt treatment but does not improve outcome for patients with oesophago-gastric cancer
- âŠ