5,063 research outputs found
Constraining compressed supersymmetry using leptonic signatures
We study the impact of the multi-lepton searches at the LHC on supersymmetric
models with compressed mass spectra. For such models the acceptances of the
usual search strategies are significantly reduced due to requirement of large
effective mass and missing E_T. On the other hand, lepton searches do have much
lower thresholds for missing E_T and p_T of the final state objects. Therefore,
if a model with a compressed mass spectrum allows for multi-lepton final
states, one could derive constraints using multi-lepton searches. For a class
of simplified models we study the exclusion limits using ATLAS multi-lepton
search analyses for the final states containing 2-4 electrons or muons with a
total integrated luminosity of 1-2/fb at \sqrt{s}=7 TeV. We also modify those
analyses by imposing additional cuts, so that their sensitivity to compressed
supersymmetric models increase. Using the original and modified analyses, we
show that the exclusion limits can be competitive with jet plus missing E_T
searches, providing exclusion limits up to gluino masses of 1 TeV. We also
analyse the efficiencies for several classes of events coming from different
intermediate state particles. This allows us to assess exclusion limits in
similar class of models with different cross sections and branching ratios
without requiring a Monte Carlo simulation.Comment: 18 pages, 5 figure
Summary of the Very Large Hadron Collider Physics and Detector Workshop
One of the options for an accelerator beyond the LHC is a hadron collider
with higher energy. Work is going on to explore accelerator technologies that
would make such a machine feasible. This workshop concentrated on the physics
and detector issues associated with a hadron collider with an energy in the
center of mass of the order of 100 to 200 TeV
Supersymmetry in the shadow of photini
Additional neutral gauge fermions -- "photini" -- arise in string
compactifications as superpartners of U(1) gauge fields. Unlike their vector
counterparts, the photini can acquire weak-scale masses from soft SUSY breaking
and lead to observable signatures at the LHC through mass mixing with the bino.
In this work we investigate the collider consequences of adding photini to the
neutralino sector of the MSSM. Relatively large mixing of one or more photini
with the bino can lead to prompt decays of the lightest ordinary supersymmetric
particle; these extra cascades transfer most of the energy of SUSY decay chains
into Standard Model particles, diminishing the power of missing energy as an
experimental handle for signal discrimination. We demonstrate that the missing
energy in SUSY events with photini is reduced dramatically for supersymmetric
spectra with MSSM neutralinos near the weak scale, and study the effects on
limits set by the leading hadronic SUSY searches at ATLAS and CMS. We find that
in the presence of even one light photino the limits on squark masses from
hadronic searches can be reduced by 400 GeV, with comparable (though more
modest) reduction of gluino mass limits. We also consider potential discovery
channels such as dilepton and multilepton searches, which remain sensitive to
SUSY spectra with photini and can provide an unexpected route to the discovery
of supersymmetry. Although presented in the context of photini, our results
apply in general to theories in which additional light neutral fermions mix
with MSSM gauginos.Comment: 23 pages, 8 figures, references adde
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Experimental Investigation of the Operating Point of a 1-kW ORC System
The organic Rankine cycle (ORC) is a promising technology for the conversion of waste heat from industrial processes as well as heat from renewable sources. Many efforts have been channeled towards maximizing the thermodynamic potential of ORC systems through the selection of working fluids and the optimal choice of operating parameters with the aim of improving overall system designs, and the selection and further development of key components. Nevertheless, experimental work has typically lagged behind modelling efforts. In this paper, we present results from tests on a small-scale (1 kWel) ORC engine consisting of a rotary-vane pump, a brazed-plate evaporator and a brazed-plate condenser, a scroll expander with a built-in volume ratio of 3.5, and using R245fa as the working fluid. An electric oil-heater acted as the heat source, providing hot oil at temperatures in the range 120-140°C. The frequency of the expander was not imposed by an inverter or the electricity grid but depended directly on the attached generator load; both the electrical load on the generator and the pump rotational speed were varied in order to investigate the performance of the system. Based on the generated data, this paper explores the relationship between the operating conditions of the ORC engine and changes in the heat-source temperature, pump and expander speeds leading to working fluid flow rates between 0.0088 kg/s and 0.0337 kg/s, from which performance maps are derived. The experimental data is, in turn, used to assess the performance of both the individual components and of the system, with the help of an exergy analysis. In particular, the exergy analysis indicates that the expander accounts for the second highest loss in the system. Analysis of the results suggests that increased heat-source temperatures, working-fluid flow rates, higher pressure ratios and larger generator loads improve the overall cycle efficiency. Specifically, a 46% increase in pressure ratio from 2.4 to 4.4 allowed a 3-fold electrical power output increase from 180 W to 550 W, and an increase in the thermal efficiency of the ORC engine from 1 to 4%. Beyond reporting on important lessons learned in improving the performance of the system under consideration, comparisons will be shown for making proper choices with respect to the interplay between heat-source temperature, generator load, and pump speed in an ORC system
Childrens friendships in super-diverse localities: Encounters with social and ethnic difference
This article explores how children make, manage, or avoid friendships in super-diverse primary school settings. We draw on interviews and pictorial data from 78 children, aged 8â9âyears across three local London primary schools to identify particular friendship groupings and the extent to which they followed existing patterns of social division. Children in the study did recognise social and cultural differences, but their friendship perceptions, affections, conflicts and practices meant that the way in which difference impacted relationships was partial and unstable. Friendship practices in the routine settings of school involved interactions across difference, but also entrenchments around similarity
Limited Lifespan of Fragile Regions in Mammalian Evolution
An important question in genome evolution is whether there exist fragile
regions (rearrangement hotspots) where chromosomal rearrangements are happening
over and over again. Although nearly all recent studies supported the existence
of fragile regions in mammalian genomes, the most comprehensive phylogenomic
study of mammals (Ma et al. (2006) Genome Research 16, 1557-1565) raised some
doubts about their existence. We demonstrate that fragile regions are subject
to a "birth and death" process, implying that fragility has limited
evolutionary lifespan. This finding implies that fragile regions migrate to
different locations in different mammals, explaining why there exist only a few
chromosomal breakpoints shared between different lineages. The birth and death
of fragile regions phenomenon reinforces the hypothesis that rearrangements are
promoted by matching segmental duplications and suggests putative locations of
the currently active fragile regions in the human genome
Prospects for Searching for Excited Leptons during RunII of the Fermilab Tevatron
This letter presents a study of prospects of searching for excited leptons
during RunII of the Fermilab Tevatron. We concentrate on single and pair
production of excited electrons in the photonic decay channel in one CDF/DO
detector equivalent for 2 fb^{-1}. By the end of RunIIa, the limits should be
easily extended beyond those set by LEP and HERA for excited leptons with mass
above about 190 GeV.Comment: 4 pages, 8 figure
Reduction of seafood processing wastewater using technologies enhanced by swimâbed technology
The increasing growth of the seafood processing industries considerably requires more industrial process activities and water consumption. It is estimated that approximately 10â40 m3 of wastewater is generated from those industries for processing one-tonne of raw materials. Due to limitations and regulations in natural resources utilization, a suitable and systematic wastewater treatment plant is very important to meet rigorous discharge standards. As a result of food waste biodegradability, the biological treatment and some extent of swim-bed technology, including a novel acryl-ïŹbre (bioïŹlm) material might be used effectively to meet the efïŹuent discharge criteria. This chapter aims to develop understanding on current problems and production of the seafood wastewater regarding treatment efïŹciency and methods of treatment
THE COST STRUCTURE OF MICROFINANCE INSTITUTIONS IN EASTERN EUROPE AND CENTRAL ASIA
Microfinance institutions are important, particularly in developing countries, because they expand the frontier of financial intermediation by providing loans to those traditionally excluded from formal financial markets. This paper presents the first systematic statistical examination of the performance of MFIs operating in Eastern Europe and Central Asia. A cost function is estimated for MFIs in the region from 1999-2004. First, the presence of subsidies is found to be associated with higher MFI costs. When output is measured as the number of loans made, we find that MFIs become more efficient over time and that MFIs involved in the provision of group loans and loans to women have lower costs. However, when output is measured as volume of loans rather than their number, this last finding is reversed. This may be due to the fact that such loans are smaller in size; thus for a given volume more loans must be made.http://deepblue.lib.umich.edu/bitstream/2027.42/40195/3/wp809.pd
Rupture of the muscle-tendon complex in tensile test. Comparison between experimentations and discrete element modeling
Tear of the muscle-tendon complex (MTC) is common
sports-related injury. Muscles are more prone to tear during
eccentric exercises when muscle contraction is com-
bined with excessive stretching (Uchiyama et al. 2011).(...
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