6,496 research outputs found
Status of the Silicon Strip Detector at CMS
The CMS Tracker is the world's largest silicon detector. It has only recently been moved underground and installed in the 4T solenoid. Prior to this there has been an intensive testing on the surface, which confirms that the detector system fully meets the design specifications. Irradiation studies with the sensor material shows that the system will survive for at least 10 years in the harsh radiation environment prevailing within the Tracker volume. The planning phase for SLHC as the successor of LHC, with a ten times higher luminosity at the same energy has already begun. First R\&D studies for more robust detector materials and a new Tracker layout have started
Geant4 Simulation of a filtered X-ray Source for Radiation Damage Studies
Geant4 low energy extensions have been used to simulate the X-ray spectra of
industrial X-ray tubes with filters for removing the uncertain low energy part
of the spectrum in a controlled way. The results are compared with precisely
measured X-ray spectra using a silicon drift detector. Furthermore, this paper
shows how the different dose rates in silicon and silicon dioxide layers of an
electronic device can be deduced from the simulations
The potential and challenges of monitoring-supported energy efficiency improvement strategies in existing buildings
The ongoing EU-supported CAMPUS 21 explores the energy efficiency potential of integrated security, control, and building management software. The main objective of the project is to compare the energy and indoor-environmental performance of a number of existing facilities before and after real or virtual implementation of monitoring-based control improvement measures
Image fusion of LM-MRI and MRA for endovascular interventions
Peripheral arterial occlusive disease can be treated with endovascular interventions. These interventions are currently intraoperatively guided by fluoroscopy. A possible alternative is LF-MRI, but the current image quality of low-field (LF) MRI may not be sufficient. The purpose of this study is to evaluate the possibility of image fusion of LF-MRI with preoperative MRA to improve the image quality. To test this, LF-MRI and 3T MRI images were made of a healthy test subject. These images were registrated using manual landmark detection. The result was a visually successful registration image of LF-MRI and anatomical MRI, which shows the possibility of manual image registration
Comparison of external and intravascular cooling to induce hypothermia in patients after CPR
Objective: Hypothermia has been shown to reduce neurologic deficits in patients after cardiopulmonary resuscitation (CPR). It was not clear if intravascular cooling is superior to standard external cooling in inducing hypothermia. Goal of this study was to compare intravascular cooling with an automated cooling device with external cooling in everyday practice on a cardiac-care ICU (intensive care unit)
Low-energy electric dipole response in 120Sn
The electric dipole strength in 120Sn has been extracted from proton
inelastic scattering experiments at E_p = 295 MeV and at forward angles
including 0 degree. Below neutron threshoild it differs from the results of a
120Sn(gamma,gamma') experiment and peaks at an excitation energy of 8.3 MeV.
The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and
is more than three times larger than what is observed with the (gamma,gamma')
reaction. This implies a strong fragmentation of the E1 strength and/or small
ground state branching ratios of the excited 1- states.Comment: 7 pages, 6 figure
A Note on Perfect Square Placement
In this note we describe the solution of perfect square placement problems with CHIP. A set of 207 perfect square placement problems from [BD92] is used. We present the constraint model in CHIP, which uses the global constraints diffn and cumulative together with a specific labeling routine for perfect placement problems. We show that all problems can be solved and present backtracking count and execution times for finding the first solution and for exploring the complete search space
Certainty Closure: Reliable Constraint Reasoning with Incomplete or Erroneous Data
Constraint Programming (CP) has proved an effective paradigm to model and
solve difficult combinatorial satisfaction and optimisation problems from
disparate domains. Many such problems arising from the commercial world are
permeated by data uncertainty. Existing CP approaches that accommodate
uncertainty are less suited to uncertainty arising due to incomplete and
erroneous data, because they do not build reliable models and solutions
guaranteed to address the user's genuine problem as she perceives it. Other
fields such as reliable computation offer combinations of models and associated
methods to handle these types of uncertain data, but lack an expressive
framework characterising the resolution methodology independently of the model.
We present a unifying framework that extends the CP formalism in both model
and solutions, to tackle ill-defined combinatorial problems with incomplete or
erroneous data. The certainty closure framework brings together modelling and
solving methodologies from different fields into the CP paradigm to provide
reliable and efficient approches for uncertain constraint problems. We
demonstrate the applicability of the framework on a case study in network
diagnosis. We define resolution forms that give generic templates, and their
associated operational semantics, to derive practical solution methods for
reliable solutions.Comment: Revised versio
Optimal General Matchings
Given a graph and for each vertex a subset of the
set , where denotes the degree of vertex
in the graph , a -factor of is any set such that
for each vertex , where denotes the number of
edges of incident to . The general factor problem asks the existence of
a -factor in a given graph. A set is said to have a {\em gap of
length} if there exists a natural number such that and . Without any restrictions the
general factor problem is NP-complete. However, if no set contains a gap
of length greater than , then the problem can be solved in polynomial time
and Cornuejols \cite{Cor} presented an algorithm for finding a -factor, if
it exists. In this paper we consider a weighted version of the general factor
problem, in which each edge has a nonnegative weight and we are interested in
finding a -factor of maximum (or minimum) weight. In particular, this
version comprises the minimum/maximum cardinality variant of the general factor
problem, where we want to find a -factor having a minimum/maximum number of
edges.
We present an algorithm for the maximum/minimum weight -factor for the
case when no set contains a gap of length greater than . This also
yields the first polynomial time algorithm for the maximum/minimum cardinality
-factor for this case
Investigating the potential of low concentrations of iron-oxide contrast agents at low magnetic field strengths for the purpose of MR guided interventions
Iron-oxide contrast agents might prove valuable in endovascular interventions at low-field MRI because their relaxivities are more favorable at lower field strengths, but still maintaining and generating positive contrast. Differences between a range concentrations of a gadolinium-based and a super paramagnetic iron-oxide (SPIO) contrast agent were compared both in simulations and experimentally on 0.25T using three different MR sequences. Optimal contrast for all sequences was found around 0.15mM for the SPIO agent and for concentrations higher than 7.0mM for the gadolinium agent. The use of low concentration SPIOs therefore is more beneficial for imaging at low magnetic field strengths than gadolinium-based contrast agents
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