1,388 research outputs found
Facilities for the Energy Frontier of Nuclear Physics
The Relativistic Heavy Ion Collider at BNL has been exploring the energy
frontier of nuclear physics since 2001. Its performance, flexibility and
continued innovative upgrading can sustain its physics output for years to
come. Now, the Large Hadron Collider at CERN is about to extend the frontier
energy of laboratory nuclear collisions by more than an order of magnitude. In
the coming years, its physics reach will evolve towards still higher energy,
luminosity and varying collision species, within performance bounds set by
accelerator technology and by nuclear physics itself. Complementary high-energy
facilities will include fixed-target collisions at the CERN SPS, the FAIR
complex at GSI and possible electron-ion colliders based on CEBAF at JLAB, RHIC
at BNL or the LHC at CERN.Comment: Invited talk at the International Nuclear Physics Conference,
Vancouver, Canada, 4-9 July 2010, to be published in Journal of Physics:
Conference Series. http://inpc2010.triumf.ca
Phase-space Analysis by Multiple Resonance-Frequency Identification: Applications to the LHC and LEP
Many beam-dynamical phenomena are studied, experimentally or computationally, by means of spectral analysis of a time-series of values of a dynamical variable. When the underlying dynamics is regular, the frequencies appearing in the spectrum are integer combinations of a small set of basic frequencies, e.g., the three tunes in the case of single-particle orbital dynamics. For well-known reasons, identification of the frequencies can be ambiguous or subjective in practice. We present an algorithm that overcomes these difficulties by exploiting theoretical bounds on the spectral power density to transform time series into sets of labelled resonance lines. In our examples, the time series are orbits obtained by tracking single particles from many initial conditions. The method has been applied to off-momentum LHC injection optics. This is a deterministic Hamiltonian system. A second application, to orbits with strong quantum fluctuations in LEP2, shows that it also works well in a noisy, dissipative system
A Three-Wave Longitudinal Test of Self-Determination Theory's Mediation Model of Engagement and Disaffection in Youth Sport.
Research adopting self-determination theory (SDT) supports a mediation model whereby coach motivational styles (autonomy support and interpersonal control) predict athletes' engagement and disaffection in youth sport via the satisfaction and frustration of psychological needs (autonomy, competence, and relatedness). Our study extends this research by examining SDT's mediation model longitudinally with three waves of data. Two hundred fifty-two youth sports participants (Mage = 12.98; SD = 1.84; range = 11-17; female n = 67) completed measures of study variables at the start, middle, and end of a competitive soccer season. Cross-lagged path analyses revealed that associations between the two coach motivational styles and athletes' engagement were mediated by psychological need satisfaction. Furthermore, a positive reciprocal association between psychological need satisfaction and engagement emerged over time. This study therefore supports the temporal assumptions underpinning SDT's mediation model but, importantly, evidences a mutually reinforcing interplay between athletes' psychological needs and their engaged behavior
Perfectionism, burnout, and engagement in dance: The moderating role of autonomy support
Previous findings highlight the relationships between 2 Ă— 2 perfectionism and burnout in dancers, but researchers are yet to examine the relationships between 2 Ă— 2 perfectionism and, the opposing outcome of, engagement in dance. Similarly, we know little about the factors that may moderate these relationships. We therefore sought to extend previous research by examining the relationships between 2 Ă— 2 perfectionism and both burnout and engagement in dancers, and by assessing whether autonomy support moderated the relationships between subtypes of perfectionism and the two opposing outcomes. Adolescent dancers (N = 244, female n = 198, M age = 15.00 years, SD = 2.90 years) completed measures capturing four subtypes of perfectionism (pure personal standards perfectionism, pure evaluative concerns perfectionism, mixed perfectionism, and non-perfectionism), burnout dimensions (reduced sense of accomplishment, emotional/physical exhaustion, devaluation), engagement dimensions (confidence, dedication, vigour, enthusiasm), and autonomy support provided by their dance teacher. Moderated regression analyses supported all four hypotheses of the 2 Ă— 2 perfectionism model for burnout (all dimensions) and dedication, vigour, and enthusiasm, and supported three hypotheses for confidence (Hypotheses 1a, 2 and 3). In addition, autonomy support moderated the relationships between subtypes of perfectionism and burnout (reduced accomplishment and devaluation) and engagement (all dimensions). The findings suggest that providing autonomy support offers a potential strategy to prevent burnout and promote engagement in perfectionistic dancers
Accelerator physics concept for upgraded LHC collimation performance
The LHC collimation system is implemented in phases, in view of the required extrapolation by 2-3 orders of magnitude beyond Tevatron and HERA experience in stored energy. All available simulations predict that the LHC proton beam intensity with the "Phase I" collimation system may be limited by the impedance of the collimators or cleaning efficiency. Maximum efficiency requires collimator materials very close to the beam, generating the dominant resistive wall impedance in the LHC. Above a certain intensity the beam is unstable. On the other hand, even if collimators are set very close to the beam, the achievable cleaning efficiency is predicted to be inadequate, requiring either beam stability beyond specifications or reduced intensity. The accelerator physics concept for upgrading cleaning efficiency, for both proton and heavy ion beams, and reducing collimator-related impedance is described. Besides the "Phase II" secondary collimators, new collimators are required in a few super-conducting regions
Physics Opportunities with the FCC-hh Injectors
In this chapter we explore a few examples of physics opportunities using the
existing chain of accelerators at CERN, including potential upgrades. In this
context the LHC ring is also considered as a part of the injector system. The
objective is to find examples that constitute sensitive probes of New Physics
that ideally cannot be done elsewhere or can be done significantly better at
theCERN accelerator complex. Some of these physics opportunities may require a
more flexible injector complex with additional functionality than that just
needed to inject protons into the FCC-hh at the right energy, intensity and
bunch structure. Therefore it is timely to discuss these options concurrently
with the conceptual design of the FCC-hh injector system.Comment: 13 pages, chapter 5 in Physics at the FCC-hh, a 100 TeV pp collide
Care homes education: what can we learn?
Medical care received by care home residents can be variable. Initiatives, such as matron-led community teams, ensure a timely response to alerts about unwell residents. But early recognition of deterioration is vital in accessing this help. The aim of this project was to design and deliver an education programme for carers. It was hypothesised that the implementation of a teaching programme may result in improved medical care for residents. By understanding the enablers and barriers to implementing teaching, we hoped to identify the components of a successful teaching programme. Four care homes in Enfield received training on topics such as deterioration recognition over a 1-year period. The project was evaluated at 3, 6 and 9 months. Each evaluation comprised: pre-and-post-teaching questionnaires, focus groups, analysis of percentages of staff trained, review of overall and potentially avoidable, hospital admission rates. A Plan-Do-Study-Act cycle structure was used. The programme was well-received by carers, who gave examples of application of learning. Modules about conditions frequently resulting in hospital admission, or concerning real cases, demonstrated the best pre-and-post lesson change scores. However, the reach of the programme was low, with attendance rates between 5% and 28%. Overall, the percentage of staff trained in deterioration recognition ranged from 35% (care home one) to 12% (care home three). Hospital admissions reduced from 37 hospital admissions to 20 over the duration of the project. Potentially avoidable admissions reduced from 16 to 5. Proving causality to the intervention was difficult. Factors facilitating delivery of training included a flexible approach, an activity-based curriculum, alignment of topics with real cases and embedding key messages in every tutorial. Barriers included: time pressures, shift work, low attendance rates, inequitable perception of the value of teaching and IT issues. Care home factors impacting on delivery included: stability of management and internal communication systems.please ensure space here
Measurements of heavy ion beam losses from collimation
The collimation efficiency for Pb ion beams in the LHC is predicted to be
lower than requirements. Nuclear fragmentation and electromagnetic dissociation
in the primary collimators create fragments with a wide range of Z/A ratios,
which are not intercepted by the secondary collimators but lost where the
dispersion has grown sufficiently large. In this article we present
measurements and simulations of loss patterns generated by a prototype LHC
collimator in the CERN SPS. Measurements were performed at two different
energies and angles of the collimator. We also compare with proton loss maps
and find a qualitative difference between Pb ions and protons, with the maximum
loss rate observed at different places in the ring. This behavior was predicted
by simulations and provides a valuable benchmark of our understanding of ion
beam losses caused by collimation.Comment: 12 pages, 20 figure
Regulation of synthesis of larval serum proteins after transplantation of larval fat body into adult Drosophila melanogaster
The larval serum proteins, LSP1 and LSP2, of Drosophila melanogaster are synthesized by the fat body during the third instar. We examined the potential for LSP synthesis by fat body implants in adult flies. Fat body from third instar donors will continue to synthesize LSPs in both males and females. Implants from late second instar larvae will start synthesizing LSP1 and LSP2 in females but only LSP1 in males, suggesting that regulation of these proteins is not the same and that the physiological milieu in the two sexes differs. The newly synthesized LSPs are secreted into the hemolymph for approximately 48 hr when secretion stops but synthesis continues. This sequence follows the pattern for LSP secretion in situ. Fat body from mid second instar larvae is variable in its ability to synthesize LSPs. LSPs are not detected in implants from first instar larvae despite there being a high level of protein synthesis in the implant and considerable growth of the fat body cells. We conclude that there is a critical stage of differentiation during the latter half of the second instar when the fat body becomes independent of the larval milieu and can synthesize LSPs in the adult.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26107/1/0000183.pd
Ion and proton loss paterns at the SPS and LHC
The collimation system of the LHC, primarily designed for proton operation, must function safely also with 208Pb82+ions. However, the particle-matter interaction in a collimator is different for heavy ions and protons. Heavy ions are subject to nuclear fragmentation, which creates a spectrum of secondary particles exiting the collimators with a Z/A ratio different from the nominal beam. These particles could be lost in a superconducting magnet and the induced heating might cause a quench. The program ICOSIM has previously been used to simulate these losses in the LHC. In this article, we present a benchmark of ICOSIM, using measured proton and ion loss maps in the SPS, and find a good qualitative agreement. We also make a quantitative comparison where the showers of the lost particles are simulated with the FLUKA code in the full magnet geometry. Here a discrepancy of a factor 3.8 is found. Estimation of expected uncertainties continues
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