Preliminary assessment of beam impact consequences on LHC Collimators

The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident, which causes the proton beam to hit a collimator, might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.peer-reviewe

Тактика ведения пациентов при синдроме Мэллори-Вейсса

МЭЛЛОРИ-ВЕЙСА СИНДРОМ /диагн /терПИЩЕВОДА ПЕРФОРАЦИЯ /диагн /терЖЕЛУДОЧНО-КИШЕЧНОЕ КРОВОТЕЧЕНИЕГЕМОСТАЗ ЭНДОСКОПИЧЕСКИ

Preliminary thermo-mechanical analysis of angular beam impact on LHC collimators

The correct functioning of the LHC Collimation System is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, accident scenarios must be well studied in order to assess their effect on the robustness of the collimators. One of the most probable accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator installation at the beam-line. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments. Such work will also help to start identifying optimal operational conditions.peer-reviewe

High energy beam impact tests on a LHC tertiary collimator at the CERN high-radiation to materials facility

The correct functioning of a collimation system is crucial to safely operate highly energetic particle accelerators, such as the Large Hadron Collider (LHC). The requirements to handle high intensity beams can be demanding. In this respect, investigating the consequences of LHC particle beams hitting tertiary collimators (TCTs) in the experimental regions is a fundamental issue for machine protection. An experimental test was designed to investigate the robustness and effects of beam accidents on a fully assembled collimator, based on accident scenarios in the LHC. This experiment, carried out at the CERN High-Radiation to Materials (HiRadMat) facility, involved 440 GeV proton beam impacts of different intensities on the jaws of a horizontal TCT. This paper presents the experimental setup and the preliminary results obtained, together with some first outcomes from visual inspection and a comparison of such results with numerical simulations.peer-reviewe

Myopathy associated BAG3 mutations lead to protein aggregation by stalling Hsp70 networks

BAG3 is a multi-domain hub that connects two classes of chaperones, small heat shock proteins (sHSPs) via two isoleucine-proline-valine (IPV) motifs and Hsp70 via a BAG domain.\ua0Mutations in either the IPV or BAG domain of BAG3 cause a dominant form of myopathy, characterized by protein aggregation in both skeletal and cardiac muscle tissues. Surprisingly, for both disease mutants, impaired chaperone binding is not sufficient to explain disease phenotypes. Recombinant mutants are correctly folded, show unaffected Hsp70 binding but are impaired in stimulating Hsp70-dependent client processing. As a consequence, the mutant BAG3 proteins become the node for a dominant gain of function causing aggregation of itself, Hsp70, Hsp70 clients and tiered interactors within the BAG3 interactome. Importantly, genetic and pharmaceutical interference with Hsp70 binding completely reverses stress-induced protein aggregation for both BAG3 mutations. Thus, the gain of function effects of BAG3 mutants act as Achilles heel of the HSP70 machinery

High energy beam impact tests on a LHC tertiary collimator at CERN HiRadMat facility

The correct functioning of the collimation system is crucial to safely operate the LHC. The requirements to handle high intensity beams can be demanding. In this respect, investigating the consequences of LHC particle beams hitting tertiary collimators (TCTs) in the experimental regions is a fundamental issue for machine protection. An experimental test was designed to investigate the robustness and effects of beam accidents on a fully assembled collimator, based on accident scenarios in the LHC. This experiment, carried out at the CERN HiRadMat (High Irradiation to Materials) facility, involved 440 GeV beam impacts of different intensities on the jaws of a horizontal TCT. This paper presents the experimental setup and the preliminary results obtained together with some first outcomes from visual inspection.peer-reviewe

Handling 1 MW losses with the LHC collimation system

The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.peer-reviewe

Consultas neurológicas e diagnósticos em um grande hospital universitário dedicado a COVID-19

Background: More than one-third of COVID-19 patients present neurological symptomsranging from anosmia to stroke and encephalopathy. Furthermore, pre-existingneurological conditions may require special treatment and may be associated with worseoutcomes. Notwithstanding, the role of neurologists in COVID-19 is probablyunderrecognized. Objective: The aim of this study was to report the reasons forrequesting neurological consultations by internists and intensivists in a COVID-19-dedicated hospital. Methods: This retrospective study was carried out at Hospital dasClínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil, a 900-bedCOVID-19 dedicated center (including 300 intensive care unit beds). COVID-19 diagnosiswas confirmed by SARS-CoV-2-RT-PCR in nasal swabs. All inpatient neurologyconsultations between March 23rd and May 23rd, 2020 were analyzed. Neurologistsperformed the neurological exam, assessed all available data to diagnose theneurological condition, and requested additional tests deemed necessary. Difficultdiagnoses were established in consensus meetings. After diagnosis, neurologists wereinvolved in the treatment. Results: Neurological consultations were requested for 89 outof 1,208 (7.4%) inpatient COVID admissions during that period. Main neurologicaldiagnoses included: encephalopathy (44.4%), stroke (16.7%), previous neurologicaldiseases (9.0%), seizures (9.0%), neuromuscular disorders (5.6%), other acute brainlesions (3.4%), and other mild nonspecific symptoms (11.2%). Conclusions: Mostneurological consultations in a COVID-19-dedicated hospital were requested for severeconditions that could have an impact on the outcome. First-line doctors should be able torecognize neurological symptoms; neurologists are important members of the medicalteam in COVID-19 hospital care.Introdução: Mais de um terço dos pacientes com COVID-19 apresentam sintomasneurológicos que variam de anosmia a AVC e encefalopatia. Além disso, doençasneurológicas prévias podem exigir tratamento especial e estar associadas a pioresdesfechos. Não obstante, o papel dos neurologistas na COVID-19 é provavelmentepouco reconhecido. Objetivo: O objetivo deste estudo foi relatar os motivos para solicitarconsultas neurológicas por clínicos e intensivistas em um hospital dedicado à COVID-19. Métodos: Estudo retrospectivo realizado no Hospital das Clínicas da Faculdade deMedicina da Universidade de São Paulo, Brasil, um centro dedicado à COVID-19 com900 leitos (incluindo 300 leitos para unidades de terapia intensiva). O diagnóstico deCOVID-19 foi confirmado por SARS-CoV-2-RT-PCR em swabs nasais. Todas asinterconsultas de neurologia hospitalar entre 23 de março e 23 de maio de 2020 foramanalisadas. Os neurologistas realizaram o exame neurológico, avaliaram todos os dadosdisponíveis para diagnosticar a patologia neurológica e solicitaram exames adicionaisconforme necessidade. Diagnósticos difíceis foram estabelecidos em reuniões deconsenso. Após o diagnóstico, os neurologistas participaram da condução dos casos.Resultados: Foram solicitadas consultas neurológicas para 89 de 1.208 (7,4%) empacientes internados por COVID-19 durante o período. Os principais diagnósticosneurológicos incluíram: encefalopatia (44,4%), acidente vascular cerebral (16,7%),doenças neurológicas prévias (9,0%), crises epilépticas (9,0%), transtornosneuromusculares (5,6%), outras lesões encefálicas agudas (3,4%) e outros sintomasleves inespecíficos (11,2%). Conclusões: A maioria das consultas neurológicas em umhospital dedicado à COVID-19 foi solicitada para condições graves que poderiam afetaro desfecho clínico. Os médicos na linha de frente devem ser capazes de reconhecersintomas neurológicos. Os neurologistas são membros importantes da equipe médica noatendimento hospitalar à COVID-19