1,137 research outputs found
T.C. Powers, '25, author of the book, "Leakage: The Bleeding of the American Economy"
No full textIncludes letters from the American Society for Testing Material about T.C. PowersBlack and WhitePeople: Powers, T.C
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Search for direct photon production in 200 A GeV S + Au reactions: A status report
No full textDirect thermal photons in the PT range of 0 - 5 GeV/c are expected to provide a sensitive probe of the hot dense matter formed in the early stage of relativistic heavy ion collisions. The production of single photons in 200 A GeV S+Au reactions has been investigated using the 3800 element Pbglass calorimeter of CERN experiment WA80. Neutral {pi}{sup o} and {eta} cross sections have been measured via their two-photon decay branch yields. In a first analysis of the WA80 results, a slight excess photon yield above that which may be accounted for by hadronic decays was observed for central collisions. A report on the status of the reanalysis of this data is presented
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(Test, calibrate, and prepare a BGO photon detector system)
No full textThe traveler spent the year at CERN primarily to test, calibrate, and prepare a BGO photon detector system for use in the August 1990 run of WA80 with sulfur beams and for use in future planned runs with an expanded BGO detector. The BGO was used in test-beam runs in December 1989 and April--May 1990 and in the August data-taking run. The Midrapidity Calorimeters (MIRAC) were also prepared in a new geometry for the August run with a new transverse energy trigger. The traveler also continued to refine and carry out simulations of photon detector systems in present and future planned photon detection experiments. The traveler participated in several WA80 collaboration meetings, which were held at CERN throughout the period of stay. Invited talks were presented at the Workshop on High Resolution Electromagnetic Calorimetry in Stockholm, Sweden, November 9--11, 1989, and at the International Workshop on Software Engineering, Artificial Intelligence, and Expert Systems for High-Energy and Nuclear Physics at Lyon, France, March 19--24, 1990. The traveler participated in an experiment to measure particle--particle correlations at 30-MeV/nucleon incident energies at the SARA facility in Grenoble from November 11--24, 1989
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Collective flow as a probe of heavy-ion reaction dynamics
No full textCollective flow of nuclear matter probes the dynamics of heavy-ion reactions and can provide information about the nuclear-matter equation of state. In particular, the incident energy dependences of collective flow may be a sensitive means to deduce the existence of a Quark Gluon Plasma phase in the equation of state. Collective flow measurements from 30 A MeV to 200 A GeV incident energies are briefly reviewed. Preliminary results on collective flow from the WA98 experiment at the CERN SPS are presented
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A neural-network approach to the problem of photon-pair combinatorics
No full textA recursive neural-network algorithm is applied to the problem of correctly pairing photons from {pi}{sup 0}, {eta}, and higher resonance decays in the presence of a large background of photons resulting from many simultaneous decays. The method uses the full information of the multi-photon final state to suppress the selection of false photon pairs which arise from the many combinatorial possibilities. The method is demonstrated for simulated photon events under semirealistic experimental conditions. 3 refs., 3 figs
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Report on the Oak Ridge workshop on Monte Carlo codes for relativistic heavy-ion collisions
No full textIn order to make detailed predictions for the case of purely hadronic matter, several Monte Carlo codes have been developed to describe relativistic nucleus-nucleus collisions. Although these various models build upon models of hadron-hadron interactions and have been fitted to reproduce hadron-hadron collision data, they have rather different pictures of the underlying hadron collision process and of subsequent particle production. Until now, the different Monte Carlo codes have, in general, been compared to different sets of experimental data, according to which results were readily available to the model builder or which Monte Carlo code was readily available to an experimental group. As a result, it has been difficult to draw firm conclusions about whether the observed deviations between experiments and calculations were due to deficiencies in the particular model, experimental discrepancies, or interesting effects beyond a simple superposition of nucleon-nucleon collisions. For this reason, it was decided that it would be productive to have a structured confrontation between the available experimental data and the many models of high-energy nuclear collisions in a manner in which it could be ensured that the computer codes were run correctly and the experimental acceptances were properly taken into account. With this purpose in mind, a Workshop on Monte Carlo Codes for Relativistic Heavy-Ion Collisions was organized at the Joint Institute for Heavy Ion Research at Oak Ridge National Laboratory from September 12--23, 1988. This paper reviews this workshop. 11 refs., 6 figs
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Electromagnetic signatures of QGP (photons): Experimental status
No full textThe direct photon measurement can provide information about the thermal evolution of the hot dense nuclear matter produced in ultra- relativistic heavy-ion collisions. However, the measurement of the transverse momentum distribution of the thermal photons is essential to obtain detailed information, in particular, about the short-lived initial hot phase. To date there has been no confirmed observation of direct thermal photon radiation in the transverse momentum region below about 3 GeV/c. On the other hand, the upper limit on the direct photon yield in S + Au reactions at large transverse momenta determined by the WA80 experiment has been shown to imply that the initial temperature of the system must be relatively low (< 250 MeV). Such low temperatures imply that the system has access to a large number of degrees of freedom, consistent with QGP formation or with a hadronic system consisting of the full spectrum of known resonances up to large mass, but inconsistent with a hadronic gas of only the lowest lying resonances. It is an interesting question how a hadronic gas consisting of the full spectrum of resonances could come into chemical equilibrium already during the initial phase of the interaction. Preliminary results from WA98 for Pb + Pb reactions indicate that there is no significant integrated direct photon excess in central collisions compared to peripheral collisions. This conclusion is based on the variation of the ratio of the electromagnetic to total transverse energy with centrality, which is consistent with no increase. The analysis of the photon data obtained with the WA98 leadglass detector is underway. Comparison of the preliminary inclusive photon spectrum to recent theoretical predictions for the thermal direct photon signal indicate that it may be observable for the case of a hadron gas, but is likely below the expected level of sensitivity for the case of QGP formation
Particle production in 158.A GeV Pb + Pb collisions
No full textThe production of neutral pions in 158.A GeV /sup 208/Pb+/sup 208/Pb collisions has been studied in the WA98 experiment. The centrality dependence of the neutral pion production is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with more than about 50 participants. The transverse mass spectrum is analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement constrains the extracted freeze-out parameters, and provides information on the freeze-out velocity profile. (18 refs)
Controversies in the management of acute tonsillitis: an evidence-based review
No full textBACKGROUND: Patients admitted with acute tonsillitis generate a substantial workload for the National Health Service (NHS), placing huge financial pressures on an already overstretched budget.OBJECTIVE OF REVIEW: Due to the difficulty of accurate diagnosis and varying practices across the UK, there exist a number of controversial areas and non-standardised practice. These will be highlighted and tackled within this article.TYPE OF REVIEW AND SEARCH STRATEGY: A literature review, last performed in September 2013, searched PubMed citing variations on the areas of controversies with 'tonsillitis', 'pharyngitis' and 'pharyngotonsillitis' - from 1956 to present with language restrictions. Excluded articles included those regarding sore throat after tonsillectomy and peritonsillar abscess.EVALUATION METHOD: Titles and abstracts were initially screened, and full text of potentially relevant articles obtained. The bibliographies of articles were searched for relevant references. The references were then compiled and reviewed independently by two authors (JB & TB), overseen by the senior author (EK).RESULTS: (i) Diagnosis and investigation: Use of the Centor criteria is inadequate within the secondary care setting. Blood testing is unnecessary in the majority of cases where patients do not require admission, as they are unlikely to change management. (ii) Antibiotics: Antibiotics are likely to be indicated in all those presenting to secondary ENT care, with penicillin being the antibiotic of choice for first-line therapy. (iii) Corticosteroids: Moderate evidence supports the benefit of steroid administration in this patient cohort, advocating a single dose initially followed by reassessment. (iv) Analgesia: Paracetamol and NSAIDs have good evidence of action. Codeine should be used with caution in the paediatric population. (v) Reduced admission rates and early discharge: There is evidence suggesting that a trial of medical therapy prior to admission is beneficial in reducing rates of admission and length of stay.CONCLUSIONS: Management of acute tonsillitis within a secondary care setting largely consists of anecdotal or relatively low-quality evidence. Thus, much evidence from management comes from expert opinion or practice within a primary care setting. Management across the UK can also vary greatly. An evidence-based review of best practice has been presented here, but further evidence will be required in the future examining the significance of corticosteroids and antibiotic administration in this patient cohort specifically, ensuring practice is evidence based and clinically relevant.</p
(13(3):51-56)酸桔葉片殊形潰瘍病斑之利用
No full textCitrus canker caused by Xanthomonas citri (Hasse) Dowson is normally charac-terized by corky, hard, and somewhat suberized lesions surrounded by a yellowish halo on the infected leaves of susceptible varieties. If the canker lesion has developed quickly under extremely favorable conditions, the white spongy tissue will excruded in some degree, and accumulated on the lesions. This special canker lesions with spongy eruption of tissue will be found, sometime, when artificial inoculation was made by overstaying the inoculated plant in pot (Fig. 4) in the inoculation chamber for three or four days after inoculation. It is also easy to induce special lesions by keeping the leaves of susceptible varieties in such a semi-vivo condition as in the moistened Petri-dish (Fig. 3) placed in the incubator for five or six days after inoculation.
The present author was deeply interested in the formation of this special lesion and had made his attempt to utilize them for several purposes, such as screen test for canker-control bactericides, identrfication of newly isolated canker organism, and determination of resistance of citrus varieties to the disease. The present report was made in deal with utilization of this inoculation technique for testing inhibiting effectiveness of the bactericides on the fomation of canker lesion.
柑桔類潰瘍病於極度適宜之環境下所發生之病斑，因罹病組識之海棉細胞受病原菌之刺激致呈畸形膨大，多量溢出，而形成白色隆起之明顯殊形病斑，此種殊形病斑頗易由人工接種而顯現。將酸桔半成熟葉片採下，以自來水沖洗後以解剖針輕刺一定數目之傷痍，浸漬於病原菌懸浮液，使葉面餘液陰乾後排放於潮濕培養皿之玻璃支架上，置28℃定溫箱培養六天，即可於傷痍部位呈現明顯之殊形潰瘍病斑。
筆者以此病斑形成之明顯與容易，乃探測其利用價值。本試驗以五種抗生製劑供作傷痍葉片人工接種後作藥劑侵漬處理，以葉片病斑發生數目，測定供試藥劑對病原菌之抑制或殺減效力。據試驗結果，病斑之發生與藥劑濃度具有規律之相關關係。筆者認為此法於藥劑試驗之初步選定上，為一簡便而可行之方法
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