Cherenkov mesons as in-medium quark energy loss

We recently showed that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons [1]. Here we review our previous holographic calculation of the energy loss in N=4 Super Yang-Mills and extend it to longitudinal vector mesons and scalar mesons. We also discuss phenomenological implications for heavy-ion collision experiments. Although the Cherenkov energy loss is an O(1/Nc) effect, a ballpark estimate yields a value of dE/dx for Nc=3 which is comparable to that of other mechanisms.

Cherenkov mesons as in-medium quark energy loss

We recently showed that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons [1]. Here we review our previous holographic calculation of the energy loss in N=4 Super Yang-Mills and extend it to longitudinal vector mesons and scalar mesons. We also discuss phenomenological implications for heavy-ion collision experiments. Although the Cherenkov energy loss is an O(1/Nc) effect, a ballpark estimate yields a value of dE/dx for Nc=3 which is comparable to that of other mechanisms.

Very-High-Energy gamma rays from a Distant Quasar: How Transparent Is the Universe?

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.

Statistical Reviewers Improve Reporting in Biomedical Articles: a Randomized Trial.

Background. Although peer review is widely considered to be the most credible way of selecting manuscripts and improving the quality of accepted papers in scientific journals, there is little evidence to support its use. Our aim was to estimate the effects on manuscript quality of either adding a statistical peer reviewer or suggesting the use of checklists such as CONSORT or STARD to clinical reviewers or both. Methodology and Principal Findings. Interventions were defined as 1) the addition of a statistical reviewer to the clinical peer review process, and 2) suggesting reporting guidelines to reviewers; with"no statistical expert" and"no checklist" as controls. The two interventions were crossed in a 262 balanced factorial design including original research articles consecutively selected, between May 2004 and March 2005, by the Medicina Clinica (Barc) editorial committee. We randomized manuscripts to minimize differences in terms of baseline quality and type of study (intervention, longitudinal, cross-sectional, others). Sample-size calculations indicated that 100 papers provide an 80% power to test a 55% standardized difference. We specified the main outcome as the increment in quality of papers as measured on the Goodman Scale. Two blinded evaluators rated the quality of manuscripts at initial submission and final post peer review version. Of the 327 manuscripts submitted to the journal, 131 were accepted for further review, and 129 were randomized. Of those, 14 that were lost to follow-up showed no differences in initial quality to the followed-up papers. Hence, 115 were included in the main analysis, with 16 rejected for publication after peer review. 21 (18.3%) of the 115 included papers were interventions, 46 (40.0%) were longitudinal designs, 28 (24.3%) cross-sectional and 20 (17.4%) others. The 16 (13.9%) rejected papers had a significantly lower initial score on the overall Goodman scale than accepted papers (difference 15.0, 95% CI: 4.6- 24.4). The effect of suggesting a guideline to the reviewers had no effect on change in overall quality as measured by the Goodman scale (0.9, 95% CI: 20.3+2.1). The estimated effect of adding a statistical reviewer was 5.5 (95% CI: 4.3-6.7), showing a significant improvement in quality. Conclusions and Significance. This prospective randomized study shows the positive effect of adding a statistical reviewer to the field-expert peers in improving manuscript quality. We did not find a statistically significant positive effect by suggesting reviewers use reporting guidelines.

The REporting of Studies Conducted Using Observational Routinely-Collected Health Data (RECORD) Statement: Methods for Arriving at Consensus and Developing Reporting Guidelines.

OBJECTIVE: Routinely collected health data, collected for administrative and clinical purposes, without specific a priori research questions, are increasingly used for observational, comparative effectiveness, health services research, and clinical trials. The rapid evolution and availability of routinely collected data for research has brought to light specific issues not addressed by existing reporting guidelines. The aim of the present project was to determine the priorities of stakeholders in order to guide the development of the REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) statement. METHODS: Two modified electronic Delphi surveys were sent to stakeholders. The first determined themes deemed important to include in the RECORD statement, and was analyzed using qualitative methods. The second determined quantitative prioritization of the themes based on categorization of manuscript headings. The surveys were followed by a meeting of RECORD working committee, and re-engagement with stakeholders via an online commentary period. RESULTS: The qualitative survey (76 responses of 123 surveys sent) generated 10 overarching themes and 13 themes derived from existing STROBE categories. Highest-rated overall items for inclusion were: Disease/exposure identification algorithms; Characteristics of the population included in databases; and Characteristics of the data. In the quantitative survey (71 responses of 135 sent), the importance assigned to each of the compiled themes varied depending on the manuscript section to which they were assigned. Following the working committee meeting, online ranking by stakeholders provided feedback and resulted in revision of the final checklist. CONCLUSIONS: The RECORD statement incorporated the suggestions provided by a large, diverse group of stakeholders to create a reporting checklist specific to observational research using routinely collected health data. Our findings point to unique aspects of studies conducted with routinely collected health data and the perceived need for better reporting of methodological issues.

Jätteen määrän vähentäminen ja jätteenkäsittelymahdollisuuksien selvittäminen pinnoitetehtaassa

EU:n mukanaan tuomat uudet vaatimukset jätteenpoltolle aiheuttavat suuria muutoksia Dynea Overlays Oy:n jätteen käsittelylle. Samalla tehdasalueella tapahtuva jätteenpoltto päättyy todennäköisesti vuoden 2005 lopulla. Tästä syystä tehtaalla syntyville jätteille haettiin uusia hävitysreittejä. Jokaiselle jätejakeelle löydettiin uusi hävitysvaihtoehto, jotka pääosin ovat jätteen hyödyntämistä energiana. Pinnoitejätteet, kovetetut hartsit ja kuitujäte hyödynnetään energiana, tyhjät kertakäyttökontit joko otetaan uudelleenkäyttöön tai toimitetaan purettuina metallin- ja muovinkeräykseen. Työn toinen tavoite oli jätteen määrän vähentäminen. Jätteen määrää vähentämällä saadaan alennettua jätteenkäsittelykustannuksia sekä parannettua saantoa. Saanto on mittari, jota seurataan Dynean kaikilla pinnoitetehtailla ympäri maailmaa. Yrityksen johto on asettanut tavoitteeksi nostaa saannon vuoden 2003 tasolta 90 % tasolle 93 % vuoden 2004 loppuun mennessä. Jo vuoden 2004 ensimmäisinä kuukausina saanto näyttää parantuneen tavoitetasolle asiaan kiinnitetyn huomion ja tarkentuneen raportoinnin seurauksena.

Spectral energy distribution of the gamma-ray microquasar LS 5039

The microquasar LS 5039 has recently been detected as a source of very high energy (VHE) $\gamma$-rays. This detection, that confirms the previously proposed association of LS 5039 with the EGRET source 3EG~J1824$-$1514, makes of LS 5039 a special system with observational data covering nearly all the electromagnetic spectrum. In order to reproduce the observed spectrum of LS 5039, from radio to VHE $\gamma$-rays, we have applied a cold matter dominated jet model that takes into account accretion variability, the jet magnetic field, particle acceleration, adiabatic and radiative losses, microscopic energy conservation in the jet, and pair creation and absorption due to the external photon fields, as well as the emission from the first generation of secondaries. The radiative processes taken into account are synchrotron, relativistic Bremsstrahlung and inverse Compton (IC). The model is based on a scenario that has been characterized with recent observational results, concerning the orbital parameters, the orbital variability at X-rays and the nature of the compact object. The computed spectral energy distribution (SED) shows a good agreement with the available observational data.

A New Mechanism of Quark Energy Loss

We show that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons. We demonstrate that this takes place in all strongly coupled, large-Nc plasmas with a gravity dual. The energy loss is exactly calculable in these models despite being an O(1/Nc)-effect. We discuss phenomenological implications for heavy-ion collision experiments.

Unification of Emission Measurements in Paper and Pulp Mills

Tässä diplomityössä tavoitteena on selvittää käytännöt ja menetelmät, joilla UPM-Kymmenen sellu-, paperi- ja vaneritehtaat ympäri maailman mittaavat ja laskevat ilmapäästönsä. Tämä tehdään kyselylomakkeella, joka lähetetään tehtaiden ympäristöpäälliköille. Kaikki tärkeimmät seikat ilmapäästöihin liittyen, kuten vaaditut jatkuvatoimiset mittaukset, jaksottaiset mittaukset, raportointikäytäntö, kalibrointi jne. kysytään lomakkeessa. Kyselylomakkeessa painotetaan mittauskäytäntöä sellutehtaissa sekä energiantuotannossa. Saatujen tulosten perusteella annetaan ehdotuksia sekä ohjeita tulevaisuutta varten, jotta mittaustulosten kokoaminen helpottuisi ja vertailukelpoisuus paranisi. Työn kirjallisuusosuudessa selvitetään yleisimmät päästölähteet sekä päästökomponentit paperi –ja selluteollisuudessa. Näiden ei toivottujen yhdisteiden syntymekanismit sekä menetelmät niiden poistamiseksi savukaasuista on myös lyhyesti kuvailtu. Myös erilaiset analysointi- ja näytteenottomenetelmät on kerrottu. Erot tehtaiden ympäristöluvissa käydään läpi, jakaen tehtaat kolmeen maantieteelliseen ryhmään. Lupakäytäntöjen osalta Suomen osuutta on painotettu, sillä UPM-Kymmene on varsin Suomikeskeinen yhtiö tehtaiden lukumääriin ja sijainteihin katsottuna. Viranomaismääräykset sekä päästörajat muutamista tehtaista on esitetty havainnollistaakseen alueellisia eroja.