A novel mechanism to produce and detect light dark matter in experiments making use of GeV electrons (and positrons) impinging on a thick target (beam dump) is proposed. The positron-rich environment ...produced by the electromagnetic shower allows us to produce an A^{'} via nonresonant (e^{+}+e^{-}→γ+A^{'}) and resonant (e^{+}+e^{-}→A^{'}) annihilation on atomic electrons. The latter mechanism, for some selected kinematics, results in a larger sensitivity with respect to limits derived by the commonly used A^{'}-strahlung. This idea, applied to beam-dump experiments and active beam-dump experiments, pushes down the current limits by an order of magnitude.
High-energy positron annihilation is a viable mechanism to produce dark photons (A′). This reaction plays a significant role in beam-dump experiments using multi-GeV electron beams on thick targets ...by enhancing the sensitivity to A′ production. The positrons produced by the electromagnetic shower can produce an A′ via nonresonant (e++e−→γ+A′) and resonant (e++e−→A′) annihilation on atomic electrons. For visible decays, the contribution of resonant annihilation results in a larger sensitivity with respect to limits derived by the commonly used A′-strahlung in certain kinematic regions. When included in the evaluation of the E137 beam-dump experiment reach, positron annihilation pushes the current limit on ϵ downwards by a factor of 2 in the range 33 MeV/c2<mA′<120 MeV/c2.
The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor involved in the proliferation and survival of cancer cells. EGFR is the first molecular target against which ...monoclonal antibodies (mAb) have been developed for cancer therapy. Here we review the mechanisms underlying the effects of EGFR-specific mAb in cancer therapy. The efficacy of EGFR-specific mAb in cancer occurs thanks to inhibition of EGFR-generated signalling; furthermore, the effects of antibodies on the immune system seem to play an important role in determining the overall anti-tumour response. In this review, attention is focused on cetuximab and panitumumab, two mAb introduced recently into clinical practice for treatment of metastatic colorectal and head and neck cancer which target the external part of EGFR.
Medium-energy electron beam-dump experiments provide an intense source of secondary muons. These particles can be used to search for muon-coupling light dark scalars that may explain the (g − 2)μ ...anomaly. We applied this idea to the SLAC E137 experiment deriving new exclusion limits and evaluated the expected sensitivity for the planned Jefferson Lab BDX experiment (in case of a null result report). The calculation is based on numerical simulations that include a realistic description of secondary muons generation in the dump, dark scalar production, propagation, and decay, and, finally, the decay product (electrons, positrons, or photons) interaction with the detector. For both experiments, exclusion limits were extended to cover a broader area in the scalar-to-muon coupling vs scalar mass parameter space. This study demonstrates that electron beam-dump experiments have an enhanced sensitivity to new physics in processes that are usually studied using proton beams.
This paper describes the design and performance of a compact detector, BDX-MINI, that incorporates all features of a concept that optimized the detection of light dark matter in the MeV-GeV mass ...range produced by electrons in a beam dump. It represents a reduced version of the future BDX experiment expected to run at JLAB. BDX-MINI was exposed to penetrating particles produced by a 2.176 GeV electron beam incident on the beam dump of Hall A at Jefferson Lab. The detector consists of 30.5 kg of PbWO
4
crystals with sufficient material following the beam dump to eliminate all known particles except neutrinos. The crystals are read out using silicon photomultipliers. Completely surrounding the detector are a passive layer of tungsten and two active scintillator veto systems, which are also read out using silicon photomultipliers. The design was validated and the performance of the robust detector was shown to be stable during a six month period during which the detector was operated with minimal access.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An unsteady one-dimensional model for the solid phase is applied to simulate the spontaneous ignition and burning of thick wood samples with grain orientation parallel or perpendicular to incident ...heat fluxes in the range 18–40 kW/m2, that is, in the absence of flame. The description of heat and mass transfer processes, at constant gas pressure, is combined with global volumetric rates of wood decomposition and char oxidation. Surface regression occurs for a limit value of char density while a critical surface temperature describes ignition. Good quantitative predictions are obtained for the ignition times and the surface temperature and mass loss rate profiles during burning. Conversion always consists of three main stages. The first short transients correspond to the formation of a relatively thin charred surface layer and glowing ignition. The second much longer stage represents a pseudo-steady-state burning, where the rates of advancement of the decomposition and oxidation zones are approximately constant as well as the surface temperature and the global rate of mass loss. Finally, the last short stage, resulting from the adiabatic bottom condition, is the enlargement of the decomposition zone to the entire sample. The first transient stage and the ignition times are noticeably affected by the external heating conditions whereas the characteristics of the pseudo-steady-state burning are mainly dependent on the char oxidation rate, which is controlled by the oxygen diffusion rate.
The CLAS12 Trigger System Raydo, B.; Boyarinov, S.; Celentano, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
960, Številka:
C
Journal Article
Recenzirano
Odprti dostop
This article describes the CLAS12 Trigger System. The simulation, hardware, and software design, as well as all validation procedures, are discussed. The firmware development tools used are discussed ...as well, including our experience with VIVADO High Level Synthesis.
Dopamine seems to mediate fear conditioning through its action on D2 receptors in the mesolimbic pathway. Systemic and local injections of dopaminergic agents showed that D2 receptors are ...preferentially involved in the expression, rather than in the acquisition, of conditioned fear. To further examine this issue, we evaluated the effects of systemic administration of the dopamine D2-like receptor antagonists sulpiride and haloperidol on the expression and extinction of contextual and cued conditioned fear in rats. Rats were trained to a context-CS or a light-CS using footshocks as unconditioned stimuli. After 24 h, rats received injections of sulpiride or haloperidol and were exposed to the context-CS or light-CS for evaluation of freezing expression (test session). After another 24 h, rats were re-exposed to the context-CS or light-CS, to evaluate the extinction recall (retest session). Motor performance was assessed with the open-field and catalepsy tests. Sulpiride, but not haloperidol, significantly reduced the expression of contextual and cued conditioned fear without affecting extinction recall. In contrast, haloperidol, but not sulpiride, had cataleptic and motor-impairing effects. The results reinforce the importance of D2 receptors in fear conditioning and suggest that dopaminergic mechanisms mediated by D2 receptors are mainly involved in the expression rather than in the extinction of conditioned freezing.
The aim of the study was to assess different outcome measures in a cohort of ambulant boys with Duchenne muscular dystrophy (DMD) over 12 months in order to establish the spectrum of possible changes ...in relation to age and steroid treatment.
The study is a longitudinal multicentric cohort study. A total of 106 ambulant patients with DMD were assessed using the 6-minute walk test (6MWT) and North Star Ambulatory Assessment (NSAA) at baseline and 12 months. Clinical data including age and steroid treatment were collected.
During the 12 months of the study, we observed a mean decline of 25.8 meters in the 6MWT with a SD of 74.3 meters. On NSAA, the mean decline was 2.2 points with a SD of 3.7. Not all the boys with DMD in our cohort showed a decline over the 12 months, with young boys showing some improvement in their 6MWT and NSAA scores up to the age of 7. NSAA and the 6MWT had the highest correlation (r = 0.52, p < 0.001).
This study provides longitudinal data of NSAA and 6MWT over a 12-month period. These data can be useful when designing a clinical trial.
Current trends show a rise of attention given to breast cancer patients' quality of life and the surgical reconstructive result. Along with this trend, surgical training quality and efficacy are ...gaining importance and innovative training methods such as online videos shared on social media portals, are becoming main updating tools. In hazardous times like COVID-19 pandemic nowadays, online communication becomes of vital importance and adaptation and innovation are fundamental to keep research and education alive. The authors aimed to investigate the role of video and multimedia sources on the daily activity and surgical training of a representative group of surgeons specifically dedicated to oncologic, oncoplastic and reconstructive breast surgeries.
A survey was produced and administered to 20 major Italian Breast Centers. Collected data were analyzed with Fisher's Exact Test.
From October 2019 to March 2020, a total of 320 surveys were collected. Among the responders, there were 188 trainees (intern medical doctors and residents) and 110 faculty, 72% of them belonged to a plastic surgery environment, while 28% to general surgery environment. Almost all respondents have ever watched videos concerning breast surgery.
The results of the study show how breast surgeons rely on videos and web platforms, mostly YouTube, when searching for training info about surgical procedures. Social media offer great opportunities for sharing knowledge and diffusion of new ideas but greater attention to their reliability is mandatory.
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