1,171 research outputs found
Development of a GEM based TPC Readout for ILD
For the International Large Detector (ILD), foreseen to be built at the
International Linear Collider (ILC), a Time Projection Chamber (TPC) is
intended to be used as the main tracking detector. The amplification will be
provided by Micro Pattern Gaseous Detectors (MPGDs). One option is the use of
Gas Electron Multipliers (GEM) in combination with a segmented pad readout
plane. The TPC group at DESY developed a modular system implementing a triple
GEM stack mounted on thin ceramic grids. This material choice allows for high
mechanical rigidity of the support structure at a reduced amount of material
and dead area compared to commonly used GRP frames.
This contribution gives an overview of the current status of this system.
This includes a discussion of points we wanted to improve over the last
generation of modules and what was implemented in the newest version. Also
improvements in the production process of the modules, which ensure a
consistent quality and present a step towards possible batch production.Comment: Talk presented at the International Workshop on Future Linear
Colliders (LCWS2016), Morioka, Japan, 5-9 December 2016. C16-12-05.
Optimization of Oil-in-Water Emulsion Stability: Experimental Design, Multiple Light Scattering, and Acoustic Attenuation Spectroscopy
To find an optimal formulation of oil-in-water (O/W) emulsions (o = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy (Ultrasizer). After matching surfactant HLB and oil required HLB, a model giving the Sauter diameter as a function of emulsifier concentration, agitation speed and emulsification time is proposed. The highest stability of C12E4-stabilized O/W emulsions is observed with 1% emulsifier
Studies on Particle Identification with dE/dx for the ILD TPC
For the International Large Detector (ILD) at the planned International
Linear Collider (ILC) a Time Projection Chamber (TPC) is foreseen as the main
tracking detector. To achieve the required point resolution, Micro Pattern
Gaseous Detectors (MPGD) will be used in the amplification stage. A readout
module using a stack of three Gas Electron Multipliers (GEM) for gas
amplification was developed at DESY. In a test campaign at the DESY II Test
Beam Facility the performance of three of these modules was investigated. In
this contribution results were presented on the particle identification
capabilities of the system using the specific energy loss (dE/dx). The results
from the prototype were used to extrapolate to the performance of the full ILD
TPC, where a dE/dx resolution of better than 5 % could be achieved. In
addition, simulation studies were performed to optimise the readout pad size
for improved dE/dx separation power. These studies also investigated the
possibility to measure the deposited energy by counting the number of
ionisation clusters (cluster counting). For small enough pads this approach was
found to give similar or better performance compared to the traditional method
of measuring the deposited charge.Comment: Talk presented at the International Workshop on Future Linear
Colliders (LCWS2018), Arlington, Texas, 22-26 October 2018. C18-10-2
Interaction of CHCN and CHNC with He : potential energy surfaces and low-energy scattering
Several nitrogen-bearing molecules, such as methyl cyanide (or acetonitrile,
CHCN) and methyl isocyanide (CHNC) of interest here, have been observed
in various astrophysical environments. The accurate modeling of their abundance
requires the calculation of rate coefficients for their collisional excitation
with species such as He atoms or H molecules at low temperatures. In this
work we compute new three-dimensional potential energy surfaces for the
CHNC-He and CHCN-He van der Waals complexes by means of the explicitly
correlated coupled cluster approach with single, double and perturbative triple
excitation CCSD(T)/F12a in conjunction with the aug-cc-pVTZ basis set. We find
a global minimum with and 58.61 cm for CHCN-He and
CHNC-He, respectively, while the dissociation energy of the complexes
are 18.64 and 18.65 cm, respectively. Low energy scattering calculations
of pure rotational (de-)excitation of CHCN and CHNC by collision with
He atoms are carried out with the close-coupling method and the collisional
cross sections of and CHNC and CHCN are computed for
kinetic energies up to 100 cm. While the PESs for both complexes are
qualitatively similar, that of CHNC-He is more anisotropic, leading to
different propensity rules for rotational excitation. For CHNC-He, we find
that || = 1 transitions are dominant at low kinetic energy and a
propensity rule that favors odd transitions is observed, whereas for
CHCN the dominant cross sections are associated to transitions with
|| = 2. We expect that the findings of this study will be beneficial
for astrophysical investigations as well as laboratory experiments
Disseminated Melioidosis Presenting with Community-Acquired Pneumonia: A Presentation Not to be Missed – A Case Report
BACKGROUND: Melioidosis commonly presents with pneumonia and is associated with a high mortality rate. This case report discussed a case of confirmed disseminated melioidosis. The case focused on the chronological clinical progressions of melioidosis which initially masqueraded as community-acquired pneumonia (CAP) and subsequently developed into septicemia. This case report aims to create awareness among the primary care doctors working in a potentially endemic area for melioidosis to be vigilant of its non-specific presentation.
CASE REPORT: We report a case of an 80-year-old man who was treated for CAP and presented with unresolved fever and subsequently sepsis. A contrast-enhanced computed tomography showed disseminated lesions of varying sizes in the lungs, liver, spleen, and blood cultures grew Burkholderia pseudomallei. A pigtail drainage catheter was inserted into the liver abscess. In addition, the patient received a 46-day course of intravenous ceftazidime and a 4-month maintenance regime of oral trimethoprim-sulfamethoxazole and oral doxycycline.
CONCLUSION: Completion of antimicrobial treatment resulted in resolution of clinical signs and abscesses on imaging
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Identification of new pillared-layered carbon nitride materials at high pressure
The compression of the layered carbon nitride C6N9H3·HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl− ions contained within C12N12 voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl− ions out of the planes beginning above 10–20 GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer bonded phase. The transition pressure is calculated to be 47 GPa for the ideal structures. The new material has mixed sp2–sp3 hybridization among the C and N atoms and it provides the first example of a pillared-layered carbon nitride material that combines the functional properties of the graphitic-like form with improved mechanical strength. Similar behavior is predicted to occur for Cl-free structures at lower pressures
Large-Eddy simulation of pulsatile blood flow
Large-Eddy simulation (LES) is performed to study pulsatile blood flow through a 3D model of arterial stenosis. The model is chosen as a simple channel with a biological type stenosis formed on the top wall. A sinusoidal non-additive type pulsation is assumed at the inlet of the model to generate time dependent oscillating flow in the channel and the Reynolds number of 1200, based on the channel height and the bulk velocity, is chosen in the simulations. We investigate in detail the transition-to-turbulent phenomena of the non-additive pulsatile blood flow downstream of the stenosis. Results show that the high level of flow recirculation associated with complex patterns of transient blood flow have a significant contribution to the generation of the turbulent fluctuations found in the post-stenosis region. The importance of using LES in modelling pulsatile blood flow is also assessed in the paper through the prediction of its sub-grid scale contributions. In addition, some important results of the flow physics are achieved from the simulations, these are presented in the paper in terms of blood flow velocity, pressure distribution, vortices, shear stress, turbulent fluctuations and energy spectra, along with their importance to the relevant medical pathophysiology
Wheels within Wheels: Making Fault Management Cost-Effective
Local design and optimization of the components of a fault management system results in sub-optimal decisions. This means that the target system will likely not meet its objectives (under-performs) or cost too much if conditions, objectives, or constraints change. We can fix this by applying a nested, management system for the fault-management system itself. We believe that doing so will produce a more resilient, self-aware, system that can operate more effectively across a wider range of conditions, and provide better behavior at closer to optimal cost.
This document summarizes the results of the Working Group 7
- ``Cost-Effective Fault Management\u27\u27 - at the Dagstuhl Seminar 09201
``Self-Healing and Self-Adaptive Systems\u27\u27 (organized by
A. Andrzejak, K. Geihs, O. Shehory and J. Wilkes).
The seminar was held from May 10th 2009 to May 15th 2009
in Schloss Dagstuhl~--~Leibniz Center for Informatics
- …