Showing papers by "Sofia University published in 2007"

CMS physics technical design report, volume II: Physics performance

Abstract: CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007. The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking--through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start-up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb−1 or less. The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z' and supersymmetric particles, Bs production and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb−1 to 30 fb−1. The Standard Model processes include QCD, B-physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the W and Z0 boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated. This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2-6 describe examples of full analyses, with photons, electrons, muons, jets, missing ET, B-mesons and τ's, and for quarkonia in heavy ion collisions. Chapters 7-15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model

Mecanismos de lesión hepatocelular

Abstract: Cell death is a process accompanying many physiological and pathological situations in organisms. The first cell death pattern that was identified was cell necrosis, described by Virchow in 1871. It was subsequently seen that cell death was an integral part of normal cell and tissue differentiation mechanisms in superior organisms. In this respect early embryological studies revealed that cell death processes were required to model organisms in their final configuration. Morphogenesis systematically entails the removal and generation of new cell and tissue structures. A similar phenomenon is encountered during metamorphosis in invertebrates and inferior vertebrates, where massive tissue involution and cell clearance are coordinately developed physiological processes. This cell death process, designated apoptosis, was characterized by Kerr in 1965. Cell apoptosis and necrosis can be differentiated by a number of both morphological and biochemical parameters. Apoptosis is a controlled removal of the involved cell with no relevant changes in cell metabolism. This process is characterized by the sequential activation of a number of proteases known as caspases, which affect cysteine-aspartate bonds in the substrate. Caspase activation entails DNA fragmentation and cell architecture changes, associated with morphological changes such as nuclear DNA condensation, decreased cell volume, and the generation of apoptotic bodies with no intracellular contents release. Necrosis results from an extreme disruption of cell balance dramatically affecting cell metabolism with a drastic decrease in cell energy contents in the form of adenosine triphosphate (ATP), ion contents changes, increased mitochondrial and cell volume, and intracellular protease activation. This process ultimately leads to a disruption of cell membranes, and release of cell contents, which promotes a secondary inflammatory response. In the liver cell apoptosis usually has a focal distribution, whereas necrosis shows a regional distribution. Despite a clear-cut differentiation between apoptosis and necrosis, both types of cell death usually coexist in the liver, because one stimulus may induce apoptosis or necrosis depending on cell type involved, exposure extent, cell metabolic status, and the integrity of the machinery involved in cell death. In this sense a number of authors have suggested that apoptosis and necrosis are no separate processes but the opposing ends in only one cell mechanism designated necrapoptosis (1). Mitochondriagenerated ATP contents are a key factor in the regulation of apoptosis or necrosis induction during the process of cell death. In this respect a lesion involving a few mitochondria may be solved by autophagia of altered organelles. If more mitochondria are involved, and an adequate amount of proapoptotic factors is released while intracellular ATP levels remain, the cell undergoes apoptosis. If the cell undergoes a severe lesion, the dramatic reduction of ATP contents will not allow for many enerMechanisms of liver cell injury

CMS physics technical design report: Addendum on high density QCD with heavy ions

Abstract: This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies , will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction ? Quantum Chromodynamics (QCD) ? in extreme conditions of temperature, density and parton momentum fraction (low-x).This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include bulk observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield tomographic information of the hottest and densest phases of the reaction.

Raman spectroscopy of ordered double perovskite La 2 Co Mn O 6 thin films

Abstract: The Raman spectra of epitaxial thin films of ${\mathrm{La}}_{2}\mathrm{Co}\mathrm{Mn}{\mathrm{O}}_{6}$ on (001)-oriented $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ substrates have been measured in several exact scattering configuration between 12 and $890\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The polarization dependence of the spectra provide clear evidence for ordered $P{12}_{1}∕n1$ structure, differing from its parent $Fm\overline{3}m$ structure by the presence of rotational distortions. The correlation between the phonon modes in $Fm\overline{3}m$, $R\overline{3}$, and $P{12}_{1}∕n1$ phases is analyzed and the corresponding types of atomic motions as well as their expected frequency range are determined by comparison to the predictions of lattice dynamical calculations. The ferromagnetic ordering and spin-phonon coupling below ${T}_{C}$ result in softening of some of the phonon modes. The evolution of the Raman spectra at high temperatures shows no indication for $P{12}_{1}∕n1--R\overline{3}$ transition up to $800\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

Altered signalling and gene expression associated with the immune system and the inflammatory response in obesity.

Abstract: White adipose tissue functions not only as an energy store but also as an important endocrine organ and is involved in the regulation of many pathological processes. The obese state is characterised by a low-grade systemic inflammation, mainly a result of increased adipocyte as well as fat resident- and recruited-macrophage activity. In the past few years, various products of adipose tissue including adipokines and cytokines have been characterised and a number of pathways linking adipose tissue metabolism with the immune system have been identified. In obesity, the pro- and anti-inflammatory effects of adipokines and cytokines through intracellular signalling pathways mainly involve the nuclear factor kappa B (NF-kappaB) and the Jun N-terminal kinase (JNK) systems as well as the I kappa B kinase beta (IKK-beta). Mitogen-activated protein kinase (MAPK) and extracellular-signal-regulated kinase (ERK) pathways, which lead to signal transducer and activator of transcription 3 (STAT3) activation, are also important in the production of pro-inflammatory cytokines. Obesity increases the expression of leptin and other cytokines, as well as some macrophage and inflammatory markers, and decreases adiponectin expression in adipose tissue. A number of cytokines, e.g. tumour necrosis factor alpha (TNF-alpha) and monocyte chemotactic protein 1 (MCP-1), and some pro-inflammatory interleukins, leuckocyte antigens, chemochines, surface adhesion molecules and metalloproteases are up-regulated whereas other factors are down-regulated. The present paper will focus on the molecular mechanisms linking obesity and inflammation with emphasis on the alteration of signalling and gene expression in adipose cell components.

Inclusive production of charged pions in p+p collisions at 158 GeV/c beam momentum

Abstract: The production of charged pions in minimum bias p+C interactions is studied using a sample of 377000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman xF. Inclusive invariant cross sections are given on a grid of 270 bins per charge, thus offering for the first time a dense coverage of the projectile hemisphere and of the cross-over region into the target fragmentation zone.

WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase Detection of the little and big blue bumps ⋆

Abstract: Context. The quasar-type blazar 3C 454.3 was observed to undergo an unprecedented optical outburst in spring 2005, affecting the source brightness from the near-IR to the X-ray frequencies. This was first followed by a millimetric and then by a radio outburst, which peaked in February 2006. Aims. In this paper we report on follow-up observations to study the multiwavelength emission in the post-outburst phase. Methods. Radio, near-infrared, and optical monitoring was performed by the Whole Earth Blazar Telescope (WEBT) collaboration in the 2006-2007 observing season. XMM-Newton observations on July 2-3 and December 18-19, 2006 added information on the X-ray and UV states of the source. Results. The source was in a faint state. The radio flux at the higher frequencies showed a fast decreasing trend, which represents the tail of the big radio outburst. It was followed by a quiescent state, common at all radio frequencies. In contrast, moderate activity characterized the near-IR and optical light curves, with a progressive increase of the variability amplitude with increasing wavelength. We ascribe this redder-when-brighter behaviour to the presence of a ""little blue bump"" due to line emission from the broad line region, which is clearly visible in the source spectral energy distribution (SED) during faint states. Moreover, the data from the XMM- Newton Optical Monitor reveal a rise of the SED in the ultraviolet, suggesting the existence of a "" big blue bump"" due to thermal emission from the accretion disc. The X-ray spectra are well fitted with a power- law model with photoelectric absorption, possibly larger than the Galactic one. However, the comparison with previous X-ray observations would imply that the amount of absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum presents a curvature, which may depend on the X-ray brightness. In this case, two scenarios are possible. i) There is no extra absorption, and the X-ray spectrum hardens at low energies, the hardening being more evident in bright states; ii) there is a constant amount of extra absorption, likely in the quasar environment, and the X-ray spectrum softens at low energies, at least in faint X-ray states. This softening might be the result of a flux contribution by the high-frequency tail of the big blue bump.

Pultrusion of a flax/polypropylene yarn

Abstract: The present work reports the pultrusion of a flax reinforced polypropylene commingled yarn containing discontinuous flax and polypropylene fibers. This was the first attempt to pultrude this material. Rectangular cross-sectional profiles have been successfully produced using a self-designed pultrusion line. In a series of experiments carried out with yarns of two different flax fiber contents, the pultrusion parameters were varied. In particular, the preheating and die temperatures and also the pulling speed, which are the most relevant parameters regarding the potential future pultrusion of natural fiber composite profiles at industrial scale. A complete characterization of each profile was conducted in order to examine the influence of processing parameters on the profile quality. The mechanical properties were evaluated by performing three point bending as well as Charpy impact tests.

IL-6 and IGF-1 are independent prognostic factors of liver steatosis and non-alcoholic steatohepatitis in morbidly obese patients.

Abstract: Lipid accumulation and other histological liver markers characterize patients with non-alcoholic steatohepatitis (NASH). The identification of non-invasive prognostic factors of liver steatosis and NASH are relevant for the unravelling of the mechanisms of this disease, as well as for the clinical diagnoses of these patients. 36 patients with morbid obesity and 12 healthy subjects were consecutively enrolled in this cross-sectional study to determine the serological parameters associated with the degree of hepatic steatosis and NASH. Clinical, biochemical and histologic variables were examined in blood and liver biopsies by descriptive, univariate and multivariate regression analysis. The patients were distributed as non-NASH (14), probably-NASH (13) and NASH (9), according to the Non-alcoholic fatty liver disease Activity Score (NAS). The study identified remarkable differences in liver steatosis, and glucose, insulin, IL-6 and IGF-1 concentrations in blood among patients with morbid obesity. IL-6 was correlated with the degree of liver steatosis until the morbidly obese patients fulfil the criteria of NASH. The patients with NASH reduced IL-6 concentration in blood. IGF-1 decreased throughout the progression of NASH. TNF-α concentration was not related to liver steatosis or NASH in morbidly obese patients.The multivariate regression analysis identified glucose >110 mg/dL, IL-6 >4.81 pg/mL and IGF-1 4.5 and IGF-1 <110 ng/mL as independent predictors of hepatic steatosis and NASH, respectively. The concentration of glucose, insulin, IL-6 and IGF-1 in blood are useful markers for the selection of patients with liver steatosis or NASH.

X Σ + 1 and a Σ + 3 states of LiCs studied by Fourier-transform spectroscopy

Abstract: We present the first high-resolution spectroscopic study of LiCs. LiCs is formed in a heat-pipe oven and studied via laser-induced fluorescence Fourier-transform spectroscopy. By exciting molecules through the $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}\text{\ensuremath{-}}B\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ and $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}\text{\ensuremath{-}}D\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ transitions vibrational levels of the $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}$ ground state have been observed up to $3\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ below the dissociation limit enabling an accurate construction of the potential. Furthermore, rovibrational levels in the $a\phantom{\rule{0.2em}{0ex}}^{3}\ensuremath{\Sigma}^{+}$ triplet ground state have been observed via singlet-triplet mixing in the higher excited states. With the help of coupled channels calculations, accurate singlet and triplet ground-state potentials were derived reaching the atomic ground-state asymptote. These potentials yield an accurate determination of the singlet and triplet ground-state dissociation energies and allow first predictions of cold collision properties of $\mathrm{Li}+\mathrm{Cs}$ pairs.

Kerr-Sen dilaton-axion black hole lensing in the strong deflection limit

Abstract: In the present work we study numerically quasiequatorial lensing by the charged, stationary, axially symmetric Kerr-Sen dilaton-axion black hole in the strong deflection limit. In this approximation we compute the magnification and the positions of the relativistic images. The most outstanding effect is that the Kerr-Sen black hole caustics drift away from the optical axis and shift in the clockwise direction with respect to the Kerr caustics. The intersections of the critical curves on the equatorial plane as a function of the black hole angular momentum are found, and it is shown that they decrease with the increase of the parameter Q{sup 2}/M. All of the lensing quantities are compared to particular cases as Schwarzschild, Kerr, and Gibbons-Maeda black holes.

Survival of genetically marked Escherichia coli O157:H7 in soil as affected by soil microbial community shifts

Abstract: A loamy sand soil sampled from a species-rich permanent grassland at a long-term experimental site (Wildekamp, Bennekom, The Netherlands) was used to construct soil microcosms in which the microbial community compositions had been modified by fumigation at different intensities (depths) As expected, increasing depth of fumigation was shown to result in progressively increasing effects on the microbiological soil parameters, as determined by cultivation-based as well as cultivation-independent (PCR-DGGE, PLFA) methods Both at 7 and at 60 days after fumigation, shifts in the bacterial, fungal and protozoan communities were noted, indicating that altered community compositions had emerged following a transition phase At the level of bacteria culturable on plates, an increase of the prevalence of bacterial r-strategists was noted at 7 days followed by a decline at 60 days, which also hinted at the effectiveness of the fumigation treatments The survival of a non-toxigenic Escherichia coli O157:H7 derivative, strain T, was then assessed over 60 days in these microcosms, using detection via colony forming units counts as well as via PCR-DGGE Both data sets were consistent with each other Thus, a clear effect of fumigation depth on the survival of the invading strain T was noted, as a progressive increase of depth coincided with a progressively enhanced inoculant survival rate As fumigation depth was presumably inversely related to community complexity, this was consistent with the hypothesis that soil systems with reduced biological complexity offer enhanced opportunities for invading microbial species to establish and persist The significance of this finding is discussed in the light of the ongoing discussion about the complexity-invasiveness relationship within microbial communities, in particular regarding the opportunities of pathogens to persist

Effect of light and temperature on the cyanobacterium Arthronema africanum - a prospective phycobiliprotein-producing strain

Abstract: The effect of light intensity (50–300 μmol photons m−2 s−1) and temperature (15–50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied Maximum growth rate was measured at 300 μmol photons m−2 s−1 and 36°C after 96 h of cultivation The chlorophyll a content increased along with the increase in light intensity and temperature and reached 24% of dry weight at 150 μmol photons m−2 s−1 and 36°C, but it decreased at higher temperatures The level of carotenoids did not change significantly under temperature changes at illumination of 50 and 100 μmol photons m−2 s−1 Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m−2 s−1 Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin The total phycobiliprotein content was extremely high, more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m−2 s−1 and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass Extremely low ( 47°C) decreased phycobiliprotein content regardless of light intensity

Region---based theory of discrete spaces: A proximity approach

Abstract: We introduce Boolean proximity algebras as a generalization of Efremovi? proximities which are suitable in reasoning about discrete regions Following Stone's representation theorem for Boolean algebras, it is shown that each such algebra is isomorphic to a substructure of a complete and atomic Boolean proximity algebra

The HARP detector at the CERN PS

Abstract: HARP is a high-statistics, large solid angle experiment to measure hadron production using proton and pion beams with momenta between 1.5 and 15 GeV/c impinging on many different solid and liquid targets from low to high Z. The experiment, located in the T9 beam of the CERN PS, took data in 2001 and 2002. For the measurement of momenta of produced particles and for the identification of particle types, the experiment includes a large-angle spectrometer, based on a Time Projection Chamber and a system of Resistive Plate Chambers, and a forward spectrometer equipped with a set of large drift chambers, a threshold Cherenkov detector, a time-of-flight wall and an electromagnetic calorimeter. The large angle system uses a solenoidal magnet, while the forward spectrometer is based on a dipole magnet. Redundancy in particle identification has been sought, to enable the cross-calibration of efficiencies and to obtain a few percent overall accuracy in the cross-section measurements. Detector construction, operation and initial physics performances are reported. In addition, the full chain for data recording and analysis, from trigger to the software framework, is described.