381 research outputs found
Design Study of the CLIC Injector and Booster Linacs with the 2007 Beam Parameters
This note presents new particle tracking studies in the CLIC Injector and Booster Linacs, which accelerate both electrons and positrons, respectively from 200 MeV to 2.42 GeV, prior to their injection into the pre-damping rings, and from 2.42 to 9 GeV, before their transport to the main accelerating linacs
A primary electron beam facility at CERN
This paper describes the concept of a primary electron beam facility at CERN,
to be used for dark gauge force and light dark matter searches. The electron
beam is produced in three stages: A Linac accelerates electrons from a
photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton
Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally,
the accelerated beam is slowly extracted to an experiment, possibly followed by
a fast dump of the remaining electrons to another beamline. The beam parameters
are optimized using the requirements of the Light Dark Matter eXperiment (LDMX)
as benchmark.Comment: 3 pages, 3 figure
CLIC Main beam dynamics in the ring to main LINAC transport
Prior to acceleration in the main linac, the particle beams created in the centrally located injector have to be transported to the outer ends of the CLIC site. This transport should not only preserve the beam quality but also shape, characterize and tune the phase space distribution to match the requirements at the entrance of the main linac. Hence, the performance of the transport downstream of the damping rings up to the main linac, the so called RTML, is crucial for the overall performance of CLIC. We discuss the different parts of the RTML and the occurring beam dynamics challenges. Their status is outlined and results of beam dynamics simulations are presented
Halo Estimates and Simulations for Linear Colliders
Halo simulations and estimates are important for the design of future linear accelerators. We describe the main processes with analytic estimates and present our generic simulations in application to the ILC
Crab cavities for linear colliders
Crab cavities have been proposed for a wide number of accelerators and
interest in crab cavities has recently increased after the successful operation
of a pair of crab cavities in KEK-B. In particular crab cavities are required
for both the ILC and CLIC linear colliders for bunch alignment. Consideration
of bunch structure and size constraints favour a 3.9 GHz superconducting,
multi-cell cavity as the solution for ILC, whilst bunch structure and
beam-loading considerations suggest an X-band copper travelling wave structure
for CLIC. These two cavity solutions are very different in design but share
complex design issues. Phase stabilisation, beam loading, wakefields and mode
damping are fundamental issues for these crab cavities. Requirements and
potential design solutions will be discussed for both colliders.Comment: 3 pages. To be published in proceedings of LINAC 2008, Victoria,
Canad
EUPRAXIA@SPARC_LAB: Beam Dynamics studies for the X-band Linac
In the framework of the Eupraxia Design Study an advanced accelerator
facility EUPRAXIA@SPARC_LAB has been proposed to be realized at Frascati
(Italy) Laboratories of INFN. Two advanced acceleration schemes will be
applied, namely an ultimate high gradient 1 GeV X-band linac together with a
plasma acceleration stage to provide accelerating gradients of the GeV/m order.
A FEL scheme is foreseen to produce X-ray beams within 3-10 nm range. A 500-TW
Laser system is also foreseen for electron and ion production experiments and a
Compton backscattering Interaction is planned together with extraction
beamlines at intermediate electron beam energy for neutron beams and THz
radiation production. The electron beam dynamics studies in the linac are here
presented together with the preliminary machine layout.Comment: 5 pages, 3 figures, NIM-A proceedings of EAAC201
Differential contribution of the MTOR and MNK pathways to the regulation of mRNA translation in meiotic and postmeiotic mouse male germ cells
Translation of stored mRNAs accounts for protein synthesis during the transcriptionally inactive stages of spermatogenesis. A key step in mRNA translation is the assembly of the initiation complex EIF4F, which is regulated by the MTOR (mammalian target of rapamycin) and MNK1/2 (MAP kinase-interacting kinase 1 and 2) pathways. We investigated the expression and activity of regulatory proteins of these pathways in male germ cells at different stages of differentiation. All translation factors analyzed were expressed in germ cells throughout spermatogenesis. However, while EIF4G and PABP1 (poly[A]-binding protein 1) were more abundant in postmeiotic cells, MTOR and its target EIF4EBP1 (4E-BP1) decreased steadily during spermatogenesis. In vivo labeling showed that pachytene spermatocytes display higher rates of protein synthesis, which are partially dependent on MTOR and MNK activity. By contrast, haploid spermatids are characterized by lower levels of protein synthesis, which are independent of the activity of these pathways. Accordingly, MTOR and MNK activity enhanced formation of the EIF4F complex in pachytene spermatocytes but not in round spermatids. Moreover, external cues differentially modulated the activity of these pathways in meiotic and haploid cells. Heat shock decreased MTOR and MNK activity in pachytene spermatocytes, whereas round spermatids were much less sensitive. On the other hand, treatment with the phosphatase inhibitor okadaic acid activated MTOR and MNK in both cell types. These results indicate that translational regulation is differentially dependent on the MTOR and MNK pathways in mouse spermatocytes and spermatids and suggest that the late stages of germ cell differentiation display constitutive assembly of the translation initiation complex
Towards a New System for the Assessment of the Quality in Care Pathways: An Overview of Systematic Reviews
Clinical or care pathways are developed by a multidisciplinary team of healthcare
practitioners, based on clinical evidence, and standardized processes. The evaluation of their
framework/content quality is unclear. The aim of this study was to describe which tools and domains
are able to critically evaluate the quality of clinical/care pathways. An overview of systematic reviews
was conducted, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses,
using Medline, Embase, Science Citation Index, PsychInfo, CINAHL, and Cochrane Library, from 2015
to 2020, and with snowballing methods. The quality of the reviews was assessed with Assessment the
Methodology of Systematic Review (AMSTAR-2) and categorized with The Leuven Clinical Pathway
Compass for the definition of the five domains: processes, service, clinical, team, and financial.
We found nine reviews. Three achieved a high level of quality with AMSTAR-2. The areas classified
according to The Leuven Clinical Pathway Compass were: 9.7% team multidisciplinary involvement,
13.2% clinical (morbidity/mortality), 44.3% process (continuity-clinical integration, transitional),
5.6% financial (length of stay), and 27.0% service (patient-/family-centered care). Overall, none of
the 300 instruments retrieved could be considered a gold standard mainly because they did not
cover all the critical pathway domains outlined by Leuven and Health Technology Assessment.
This overview shows important insights for the definition of a multiprinciple framework of core
domains for assessing the quality of pathways. The core domains should consider general critical
aspects common to all pathways, but it is necessary to define specific domains for specific diseases,
fast pathways, and adapting the tool to the cultural and organizational characteristics of the health
system of each country
Interaction point feedback design and integrated simulations to stabilize the CLIC final focus
International audienceThe Compact Linear Collider (CLIC) accelerator has strong precision requirements on offset position between the beams. The beam which is sensitive to ground motion needs to be stabilized to unprecedented requirements. Different Beam Based Feedback (BBF) algorithms such as Orbit Feedback (OFB) and Beam-Beam Offset Feedback (BBOF) have been designed. This paper focuses on the BBOF control which could be added to the CLIC baseline. It has been tested for different ground motion models in the presence of noises or disturbances and uses digital linear control with or without an adaptive loop. The simulations demonstrate that it is possible to achieve the required performances and quantify the maximum allowed noise level. This amount of admitted noises and disturbances is given in terms of an equivalent disturbance on the position of the magnet that controls the beam offset. Due to the limited sampling frequency of the process, the control loop is in a very small bandwidth. The study shows that these disturbances have to be lowered by other means in the higher frequency range
Face Mask Use in the Community for Reducing the Spread of COVID-19: A Systematic Review.
Background: Evidence is needed on the effectiveness of wearing face masks in the community to prevent SARS-CoV-2 transmission. Methods: Systematic review and meta-analysis to investigate the efficacy and effectiveness of face mask use in a community setting and to predict the effectiveness of wearing a mask. We searched MEDLINE, EMBASE, SCISEARCH, The Cochrane Library, and pre-prints from inception to 22 April 2020 without restriction by language. We rated the certainty of evidence according to Cochrane and GRADE approach. Findings: Our search identified 35 studies, including three randomized controlled trials (RCTs) (4,017 patients), 10 comparative studies (18,984 patients), 13 predictive models, nine laboratory experimental studies. For reducing infection rates, the estimates of cluster-RCTs were in favor of wearing face masks vs. no mask, but not at statistically significant levels (adjusted OR 0.90, 95% CI 0.78–1.05). Similar findings were reported in observational studies. Mathematical models indicated an important decrease in mortality when the population mask coverage is near-universal, regardless of mask efficacy. In the best-case scenario, when the mask efficacy is at 95%, the R0 can fall to 0.99 from an initial value of 16.90. Levels of mask filtration efficiency were heterogeneous, depending on the materials used (surgical mask: 45–97%). One laboratory study suggested a viral load reduction of 0.25 (95% CI 0.09–0.67) in favor of mask vs. no mask. Interpretation: The findings of this systematic review and meta-analysis support the use of face masks in a community setting. Robust randomized trials on face mask effectiveness are needed to inform evidence-based policies. PROSPERO registration: CRD42020184963
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