Physics of ultra-peripheral collisions with ALICE at the LHC

The photoproduction of vector mesons in ultra-peripheral collisions (UPC) is a powerful tool to probe the nuclear gluon distribution (Pb-Pb collisions) and the gluon structure function in the proton (p-Pb collisions). The first measurements of coherent photoproduced J/ψ and ψ(2S) in Pb-Pb collisions at √sNN = 2.76TeV, performed with the ALICE detector, are reported and compared to STARLIGHT and QCD based models, in order to investigate nuclear gluon shadowing. The first results of the measurement of exclusive J/ψ photoproduction off protons in p-Pb collisions at √sNN = 5.02TeV performed by the ALICE Collaboration are also mentioned

Water washing of axial flow compressors: Numerical study on the fate of injected droplets

In turbomachinery applications blade fouling represents a main cause of performance degradation. Among the different techniques currently available, online water washing is one of the most effective in removing deposit from the blades. Since this kind of washing is applied when the machine is close to design conditions, injected droplets are strongly accelerated when they reach the rotor blades and the understanding of their interaction with the blades is not straightforward. Moreover, undesirable phenomena like blades erosion or liquid film formation can occur. The present study aims at assessing droplets dragging from the injection system placed at the compressor inlet till the first stage rotor blades, with a focus on droplets impact locations, on the washing process and the associated risk of erosion. 3D numerical simulations of the whole compressor geometry (up to the first rotor stage) are performed by using Ansys Fluent to account for the asymmetric distribution of the sprays around of the machine struts, IGV and rotor blades. The simulations are carried out by adopting the k-ϵ realizable turbulence model with standard wall functions, coupled with the discretephase model to track injected droplets motion. Droplets-wall interaction is also accounted for by adopting the Stanton-Rutland model which define a droplet impact outcome depending on the impact conditions. The induced erosion is evaluated by adopting an erosion model previously developed by some of the authors and implemented in Fluent through the use of a User Defined Function (UDF). Two sets of simulations are performed, by considering the rotor still and rotating, representative of off-line and on-line water washing conditions, respectively. In the rotating simulation, the Multiple Reference Frame Model is used. The obtained results demonstrate that the washing process differs substantially between the fixed and the rotating case. Moreover, to quantify the water washing effectiveness and the erosion risk, new indices were introduced and computed for the main components of the machine. These indices can be considered as useful prescriptions in the optimization process of water washing systems

Persistent storage of non-event data in the CMS databases

In the CMS experiment, the non event data needed to set up the detector, or being produced by it, and needed to calibrate the physical responses of the detector itself are stored in ORACLE databases. The large amount of data to be stored, the number of clients involved and the performance requirements make the database system an essential service for the experiment to run. This note describes the CMS condition database architecture, the data-flow and PopCon, the tool built in order to populate the offline databases. Finally, the first results obtained during the 2008 and 2009 cosmic data taking are presented.In the CMS experiment, the non event data needed to set up the detector, or being produced by it, and needed to calibrate the physical responses of the detector itself are stored in ORACLE databases. The large amount of data to be stored, the number of clients involved and the performance requirements make the database system an essential service for the experiment to run. This note describes the CMS condition database architecture, the data-flow and PopCon, the tool built in order to populate the offline databases. Finally, the first experience obtained during the 2008 and 2009 cosmic data taking are presented

Sphingosine-1-phosphate modulates vascular permeability and cell recruitment inacute inflammation in vivo.

The sphingosine kinase (SPK)/sphingosine-1-phosphate (S1P) pathway recently has been associated with a variety of inflammatory-based diseases. The majority of these studies have been performed in vitro. Here, we have addressed the relevance of the SPK/S1P pathway in the acute inflammatory response in vivo by using different well known preclinical animal models. The study has been performed by operating a pharmacological modulation using 1) L-cycloserine and DL-threo-dihydrosphingosine (DTD), S1P synthesis inhibitors or 2) 2-undecyl-thiazolidine-4-carboxylic acid (BML-241) and N-(2,6-dichloro-4-pyridinyl)-2-[1,3-dimethyl-4-(1-methylethyl)-1H-pyrazolo[3,4-b]pyridin-6-yl]-hydrazinecarboxamide (JTE-013), specific S1P(2) and S1P(3) receptor antagonists. After local injection of carrageenan in mouse paw S1P release significantly increases locally and decreases during the resolution phase. Expression of SPKs and S1P(2) and S1P(3) receptors is increased in inflamed tissues. Administration of L-cycloserine or DTD caused a significant anti-inflammatory effect. By using different animal models we have also demonstrated that the SPK/S1P pathway contributes to changes in vascular permeability and promotes cell recruitment. The S1P effect on cell recruitment results is receptor-mediated because both JTE-013 and BML-241 inhibited zymosan-induced cell chemotaxis without effect on vascular leakage. Conversely, changes in vascular permeability involve mainly SPK activity, because compound 48/80-induced vascular leakage was significantly inhibited by DTD. In conclusion, the SPK/S1P pathway is involved in acute inflammation and could represent a valuable therapeutic target for developing a new class of anti-inflammatory drugs

A simulation tool for MRPC telescopes of the EEE project

The Extreme Energy Events (EEE) Project is mainly devoted to the study of the secondary cosmic ray radiation by using muon tracker telescopes made of three Multigap Resistive Plate Chambers (MRPC) each. The experiment consists of a telescope network mainly distributed across Italy, hosted in different building structures pertaining to high schools, universities and research centers. Therefore, the possibility to take into account the effects of these structures on collected data is important for the large physics programme of the project. A simulation tool, based on GEANT4 and using GEMC framework, has been implemented to take into account the muon interaction with EEE telescopes and to estimate the effects on data of the structures surrounding the experimental apparata.A dedicated event generator producing realistic muon distributions, detailed geometry and microscopic behavior of MRPCs have been included to produce experimental-like data. The comparison between simulated and experimental data, and the estimation of detector resolutions is here presented and discussed

A new approach in modeling the response of RPC detectors

The response of RPC detectors is highly sensitive to environmental variables. A novel approach is presented to model the response of RPC detectors in a variety of experimental conditions. The algorithm, based on Artificial Neural Networks, has been developed and tested on the CMS RPC gas gain monitoring system during commissioning

Multiplicity Studies and Effective Energy in ALICE at the LHC

In this work we explore the possibility to perform ``effective energy'' studies in very high energy collisions at the CERN Large Hadron Collider (LHC). In particular, we focus on the possibility to measure in $pp$ collisions the average charged multiplicity as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading baryons with the Zero Degree Calorimeters. Analyses of this kind have been done at lower centre--of--mass energies and have shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties: no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality picture can be extended to {\it ion--ion} collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting fragmentation has been used to derive the expected charged event multiplicity in $AA$ interactions at LHC. This leads to scenarios where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe high energy $AA$ collisions. A mean charged multiplicity of about 1000-2000 per rapidity unit (at $\eta \sim 0$) is expected for the most central $Pb-Pb$ collisions at $\sqrt{s_{NN}} = 5.5 TeV$.Comment: 12 pages, 19 figures. In memory of A. Smirnitski

Risk Factors for Symptomatic Hyperlactatemia and Lactic Acidosis Among Combination Antiretroviral Therapy-Treated Adults in Botswana: Results from a Clinical Trial

Nucleoside analogue reverse transcriptase inhibitors are an integral component of combination antiretroviral treatment regimens. However, their ability to inhibit polymerase-γ has been associated with several mitochondrial toxicities, including potentially life-threatening lactic acidosis. A total of 650 antiretroviral-naive adults (69% female) initiated combination antiretroviral therapy (cART) and were intensively screened for toxicities including lactic acidosis as part of a 3-year clinical trial in Botswana. Patients were categorized as no lactic acidosis symptoms, minor symptoms but lactate <4.4 mmol/liter, and symptoms with lactate ≥ 4.4 mmol/liter [moderate to severe symptomatic hyperlactatemia (SH) or lactic acidosis (LA)]. Of 650 participants 111 (17.1%) developed symptoms and/or laboratory results suggestive of lactic acidosis and had a serum lactate drawn; 97 (87.4%) of these were female. There were 20 events, 13 having SH and 7 with LA; all 20 (100%) were female (p<0.001). Cox proportional hazard analysis limited to the 451 females revealed that having a higher baseline BMI was predictive for the development of SH/LA [aHR=1.17 per one-unit increase (1.08-1.25), p<0.0001]. Ordered logistic regression performed among all 650 patients revealed that having a lower baseline hemoglobin [aOR=1.28 per one-unit decrease (1.1-1.49), p=0.002] and being randomized to d4T/3TC-based cART [aOR=1.76 relative to ZDV/3TC (1.03-3.01), p=0.04] were predictive of the symptoms and/or the development of SH/LA. cART-treated women in sub-Saharan Africa, especially those having higher body mass indices, should receive additional monitoring for SH/LA. Women presently receiving d4T/3TC-based cART in such settings also warrant more intensive monitoring

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets