Towards an OpenMP Specification for Critical Real-Time Systems

OpenMP is increasingly being considered as a convenient parallel programming model to cope with the performance requirements of critical real-time systems. Recent works demonstrate that OpenMP enables to derive guarantees on the functional and timing behavior of the system, a fundamental requirement of such systems. These works, however, focus only on the exploitation of fine grain parallelism and do not take into account the peculiarities of critical real-time systems, commonly composed of a set of concurrent functionalities. OpenMP allows exploiting the parallelism exposed within real-time tasks and among them. This paper analyzes the challenges of combining the concurrency model of real-time tasks with the parallel model of OpenMP. We demonstrate that OpenMP is suitable to develop advanced critical real-time systems by virtue of few changes on the specification, which allow the scheduling behavior desired (regarding execution priorities, preemption, migration and allocation strategies) in such systems.The research leading to these results has received funding from the Spanish Ministry of Science and Innovation, under contract TIN2015-65316-P, and from the European Union's Horizon 2020 Programme under the CLASS Project (www.classproject. eu), grant agreement No 780622.Peer ReviewedPostprint (author's final draft

Ultra-High Energy Cosmic Rays and Stable H-dibaryon

It is shown that an instanton induced interaction between quarks produces a very deeply bound H-dibaryon with mass below 2M_N, M_H=1718 MeV. Therefore the H-dibaryon is predicted to be a stable particle. The reaction of photodisintegration of H-dibaryon to $2\Lambda$ in during of its penetration into cosmic microwave background will result in a new possible cut-off in the cosmic-ray spectrum. This provides an explanation of ultra-high energy cosmic ray events observed above the GZK cut-off as a result of the strong interaction of high energy H-dibaryons from cosmic rays with nuclei in Earth's atmosphere.Comment: 5 pages, Late

Experimental determination of the complete spin structure for anti-proton + proton -> anti-\Lambda + \Lambda at anti-proton beam momentum of 1.637 GeV/c

The reaction anti-proton + proton -> anti-\Lambda + \Lambda -> anti-proton + \pi^+ + proton + \pi^- has been measured with high statistics at anti-proton beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin target combined with the self-analyzing property of \Lambda/anti-\Lambda decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of eleven real parameters for each bin of scattering angle, each of these parameters is determined with reasonable precision. From these results all conceivable spin-correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in anti-proton + proton -> anti-\Lambda + \Lambda near this energy. Existing theoretical models do not give good predictions for those spin-observables that had not been previously measured.Comment: To be published in Phys. Rev. C. Tables of results (i.e. Ref. 24) are available at http://www-meg.phys.cmu.edu/~bquinn/ps185_pub/results.tab 24 pages, 16 figure

Neutron Star Constraints on the H Dibaryon

We study the influence of a possible H dibaryon condensate on the equation of state and the overall properties of neutron stars whose population otherwise contains nucleons and hyperons. In particular, we are interested in the question of whether neutron stars and their masses can be used to say anything about the existence and properties of the H dibaryon. We find that the equation of state is softened by the appearance of a dibaryon condensate and can result in a mass plateau for neutron stars. If the limiting neutron star mass is about that of the Hulse-Taylor pulsar a condensate of H dibaryons of vacuum mass 2.2 GeV and a moderately attractive potential in the medium could not be ruled out. On the other hand, if the medium potential were even moderately repulsive, the H, would not likely exist in neutron stars. If neutron stars of about 1.6 solar mass were known to exist, attractive medium effects for the H could be ruled out. Certain ranges of dibaryon mass and potential can be excluded by the mass of the Hulse-Taylor pulsar which we illustrate graphically.Comment: Revised by the addition of a figure showing the region of dibaryon mass and potential excluded by the Hulse-Taylor pulsar. 18 pages, 11 figures, latex (submitted to Phys. Rev. C

Measurement of Spin Transfer Observables in Antiproton-Proton -> Antilambda-Lambda at 1.637 GeV/c

Spin transfer observables for the strangeness-production reaction Antiproton-Proton -> Antilambda-Lambda have been measured by the PS185 collaboration using a transversely-polarized frozen-spin target with an antiproton beam momentum of 1.637 GeV/c at the Low Energy Antiproton Ring at CERN. This measurement investigates observables for which current models of the reaction near threshold make significantly differing predictions. Those models are in good agreement with existing measurements performed with unpolarized particles in the initial state. Theoretical attention has focused on the fact that these models produce conflicting predictions for the spin-transfer observables D_{nn} and K_{nn}, which are measurable only with polarized target or beam. Results presented here for D_{nn} and K_{nn} are found to be in disagreement with predictions from existing models. These results also underscore the importance of singlet-state production at backward angles, while current models predict complete or near-complete triplet-state dominance.Comment: 5 pages, 3 figure

Can Doubly Strange Dibaryon Resonances be Discovered at RHIC?

The baryon-baryon continuum invariant mass spectrum generated from relativistic nucleus + nucleus collision data may reveal the existence of doubly-strange dibaryons not stable against strong decay if they lie within a few MeV of threshold. Furthermore, since the dominant component of these states is a superposition of two color-octet clusters which can be produced intermediately in a color-deconfined quark-gluon plasma (QGP), an enhanced production of dibaryon resonances could be a signal of QGP formation. A total of eight, doubly-strange dibaryon states are considered for experimental search using the STAR detector (Solenoidal Tracker at RHIC) at the new Relativistic Heavy Ion Collider (RHIC). These states may decay to Lambda-Lambda and/or proton-Cascade-minus, depending on the resonance energy. STAR's large acceptance, precision tracking and vertex reconstruction capabilities, and large data volume capacity, make it an ideal instrument to use for such a search. Detector performance and analysis sensitivity are studied as a function of resonance production rate and width for one particular dibaryon which can directly strong decay to proton-Cascade-minus but not Lambda-Lambda. Results indicate that such resonances may be discovered using STAR if the resonance production rates are comparable to coalescence model predictions for dibaryon bound states.Comment: 28 pages, 5 figures, revised versio

Mental distress, alcohol use and help-seeking among medical and business students: a cross-sectional comparative study

<p>Abstract</p> <p>Background</p> <p>Stress and distress among medical students are thoroughly studied and presumed to be particularly high, but comparative studies including other student groups are rare.</p> <p>Methods</p> <p>A web-based survey was distributed to 500 medical students and 500 business students. We compared levels of study stress (HESI), burnout (OLBI), alcohol habits (AUDIT) and depression (MDI), and analysed their relationship with self-assessed mental health problems by logistic regression, with respect to gender.</p> <p>Results</p> <p>Medical students' response rate was 81.6% and that of business students 69.4%. Business students scored higher on several study stress factors and on disengagement. Depression (OR 0.61, CI₉₅0.37;0.98) and harmful alcohol use (OR 0.55, CI₉₅0.37; 0.75) were both less common among medical students. However, harmful alcohol use was highly prevalent among male students in both groups (medical students 28.0%, business students 35.4%), and among female business students (25.0%). Mental health problems in need of treatment were equally common in both groups; 22.1% and 19.3%, respectively, and was associated with female sex (OR 2.01, CI₉₅1.32;3.04), exhaustion (OR 2.56, CI₉₅1.60;4.10), lower commitment to studies (OR 1.95, CI₉₅1.09;3.51) and financial concerns (OR 1.81 CI₉₅1.18;2.80)</p> <p>Conclusions</p> <p>Medical students may not be more stressed than other high achieving student populations. The more cohesive structure of medical school and a higher awareness of a healthy lifestyle may be beneficial factors.</p

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

How the "H-particle" unravels the quark dynamics

It is shown that the short-range part of the Goldstone boson exchange interaction between the constituent quarks which explains baryon spectroscopy and the short-range repulsion in the NN system induces a strong short-range repulsion in the flavour-singlet state of the $\Lambda\Lambda$ system with $J^P=0^+$. It then suggests that a deeply bound H-particle should not exist. We also compare our approach with other models employing different hyperfine interactions between quarks in the nonperturbative regime of QCD.Comment: 9 pages. Section, devoted to the numerical estimate of the "H-particle" channel with the Goldstone boson exchange model, is extended. Discussion on the possible role of instantons is esentially modifie