Dark Sector Physics with Belle II Corona, L
Journal of physics. Conference series,
04/2020, Letnik:
1526, Številka:
1
Journal Article
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The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the KEKB facility at the Japanese KEK laboratory. The design luminosity of the machine is 8 · 1035 ...cm−2s−1 and the Belle II experiment aims to record 50 ab−1 of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, where about 0.5 fb−1 of data have been collected. Regular operation of SuperKEKB has started in March 2019: the machine has achieved a peak luminosity of 1034 cm−2s−1, and Belle II has recorded a data sample of about 6.5 fb−1. Already this early data set with specifically designed triggers offers the possibility to search for a large variety of dark sector particles in the GeV mass range complementary to searches at LHC and dedicated low energy experiments. The Belle II dark matter analyses will benefit from more data in the process of being accumulated. This talk will review the state of the dark sector searches at Belle II with a focus on the discovery potential of the early data, and show the first results.
Proton–hydride tautomerism in hydrogen evolution catalysis Quintana, Luis M. Aguirre; Johnson, Samantha I.; Corona, Sydney L. ...
Proceedings of the National Academy of Sciences - PNAS,
06/2016, Letnik:
113, Številka:
23
Journal Article
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Efficient generation of hydrogen from renewable resources requires development of catalysts that avoid deep wells and high barriers. Information about the energy landscape for H₂ production can be ...obtained by chemical characterization of catalytic intermediates, but few have been observed to date. We have isolated and characterized a key intermediate in 2e⁻ + 2H⁺ → H₂ catalysis. This intermediate, obtained by treatment of Cp*Rh(bpy) (Cp*, η⁵-pentamethylcyclopentadienyl; bpy, κ²-2,2′-bipyridyl) with acid, is not a hydride species but rather, bears η⁴-Cp*H as a ligand. Delivery of a second proton to this species leads to evolution of H₂ and reformation of η⁵-Cp* bound to rhodium(III). With suitable choices of acids and bases, the Cp*Rh(bpy) complex catalyzes facile and reversible interconversion of H⁺ and H₂.
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► The carbon cloth electrode adsorbs a significant quantity of hydrocarbons during the electrokinetic process. ► The Ti|IrO2–Ta2O5 electrode was a good material for electro-oxidate ...organic compounds. ► The electrodes in direct contact with the polluted soil were better than those separated by a physical barrier, because it increased the efficiency of the electrokinetic process.
There are diverse alternatives for treating polluted soil. However, one of the most promising and innovating technologies is the electrokinetic remediation process. In the electrokinetic process, pollutant removal is influenced by several factors such as the material used as electrodes and their arrangement in the electrokinetic system, among others.
This paper investigates the feasibility of removing hydrocarbon from a polluted soil, analyzing first some properties of different electrode materials by electrochemical techniques for the purpose of selecting the best to be used as an anode in the electrokinetic process. Also, two different cathode materials were tested during the electrokinetic remediation process – carbon cloth and titanium. However, results indicated the carbon cloth adsorbed the organic compounds; for that reason, it was discarded from the electrokinetic remediation process.
In addition, two electrode arrangements were evaluated in the electrokinetic system, those where the electrodes were in direct contact with the soil and those where the electrodes were separated from soil by a physical barrier. The first array showed less electrical resistance and more hydrocarbon removal than the second.
Families of young children with autism spectrum disorder (ASD) frequently experience barriers to accessing evidence-based early intervention services. Telemedicine presents an opportunity to increase ...access to these services, particularly for families in rural and under-resourced areas. The present article describes a brief behavioral intervention and support model for families of young children with concerns for ASD. In the context of the COVID-19 pandemic, this service model shifted to telemedicine-only service delivery, resulting in an opportunity to analyze intervention outcomes from services delivered either via traditional in-person visits, telemedicine-only sessions, or a hybrid model including both in-person and telemedicine sessions.
Data are presented for 115 families with toddlers 16-33 months of age who participated in a six-session behavioral intervention and support service model either in-person, through telemedicine, or through a hybrid service model. This intervention was available for families referred for ASD evaluation through the state Part C early intervention program. Intervention feasibility, fidelity of implementation, child outcomes, and stakeholder satisfaction are compared across service delivery models.
Caregivers, behavioral consultants, and Part C early intervention providers reported satisfaction with services, regardless of service delivery model. Caregivers and consultants also reported positive child outcomes. Statistically significant differences emerged for caregiver- and consultant-reported child outcomes in some domains, with stakeholders in the telemedicine-only group reporting slightly less improvement, compared to stakeholders in the in-person-only group. Caregivers and consultants in the telemedicine-only group also provided qualitative feedback on benefits and challenges related to telemedicine services.
Both caregivers and behavioral consultants reported positive outcomes following a brief behavioral intervention and support model targeted at families of young children with concern for ASD. Stakeholders reported improvement in child behavior and satisfaction with services across in-person, telemedicine-only, and hybrid models of service delivery. These results suggest that telemedicine presents a promising opportunity for increasing service access. Additional research is needed to continue optimizing the experience of telemedicine-based service delivery for both families and intervention providers.
The DMAPS upgrade of the Belle II vertex detector Babeluk, M.; Barbero, M.; Baudot, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
Recenzirano
The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028.
One ...proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk).
This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development.
This study evaluated the association between anorexia of aging and nutrients intake. It was a cross-sectional study with 130 individuals aged 60 years or older, undergoing outpatient care in the city ...of Campinas, São Paulo. Anorexia of Aging (AA) was assessed using the Simplified Nutrition Appetite Questionnaire (SNAQ), and food consumption was evaluated using the 24-hour recall (24HR). The prevalence of AA was 27.7%, in which 66.7% were women and 38.9% were older than 80 years. Elderly with AA presented lower intake of calories (1172.6 kcal vs 1477.9 kcal; p = 0.003), carbohydrates (158.5 g vs 194.1 g; p = 0.015), proteins (49.9 g vs 68.5 g; p = 0.004) and lipids (34.6 g vs 46.1 g; p = 0.006). They also had lower intake of fibers (12.6 g vs 19.4 g; p < 0.001), iron (6.4 mg vs 8.9 mg; p < 0.001) and zinc (6.0 mg vs 8.5 mg; p = 0.004). Our results show that intake of most nutrients is significantly lower in AA elderly, except carbohydrates, which may point to worse-quality diets. The diagnosis of AA, as well as the evaluation of elderly food intake, are essential to prevent undernutrition, vulnerabilities, and increased morbidity and mortality.
The Silicon Vertex Detector of the Belle II experiment Wang, Z.; Adamczyk, K.; Aggarwal, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2024, Letnik:
1061
Journal Article
Recenzirano
Odprti dostop
The Belle II experiment located at KEK, Japan takes data from asymmetric e+e− collision provided by the SuperKEKB accelerator. The Silicon Vertex Detector (SVD), which is part of the Belle II Vertex ...Detector (VXD), has been operating smoothly and reliably since the start of data taking in March 2019. In this article, we report on the performance of the SVD in terms of the large signal-to-noise ratio, the good hit position resolution as well as the good hit-time resolution. New algorithms based on hit-time information are under development to improve robustness of tracking performance within the anticipated high background environment. The Background situation of the SVD has been constantly monitored and no degradation in performance is observed so far. To investigate the SVD performance at high luminosity runs in the future, simulation as well as an irradiation campaign are launched and their results are summarized. During the first long shutdown of the Belle II experiment, which starts from June 2022, the VXD has been refurbished with a new two-layer DEPFET pixel detector located inside the SVD. All the delicate phases of the disassembly, re-assembly and installation of the new VXD have been successfully completed. The new VXD commissioning phase began in Sept 2023 to get ready for beam operation starting in early 2024.
Pelvic floor muscle stretch injury during pregnancy and birth is associated with the incidence of stress urinary incontinence (SUI), a condition that affects 30-60% of the female population and is ...characterized by involuntary urine leakage during physical activity, further exacerbated by aging. Aging and multiparous rabbits suffer pelvic nerve and muscle damage, resulting in alterations in pelvic floor muscular contraction and low urethral pressure, resembling SUI. However, the extent of nerve injury is not fully understood. Here, we used electron microscopy analysis of pelvic and perineal nerves in multiparous rabbits to describe the extent of stretch nerve injury based on axon count, axon size, myelin-to-axon ratio, and elliptical ratio. Compared to young nulliparous controls, mid-age multiparous animals showed an increase in the density of unmyelinated axons and in myelin thickness in both nerves, albeit more significant in the bulbospongiosus nerve. This revealed a partial but sustained damage to these nerves, and the presence of some regenerated axons. Additionally, we tested whether electrical stimulation of the bulbospongiosus nerve would induce muscle contraction and urethral closure. Using a miniature wireless stimulator implanted on this perineal nerve in young nulliparous and middle age multiparous female rabbits, we confirmed that these partially damaged nerves can be acutely depolarized, either at low (2-5 Hz) or medium (10-20 Hz) frequencies, to induce a proportional increase in urethral pressure. Evaluation of micturition volume in the mid-age multiparous animals after perineal nerve stimulation, effectively reversed a baseline deficit, increasing it 2-fold (p = 0.02). These results support the notion that selective neuromodulation of pelvic floor muscles might serve as a potential treatment for SUI.
The silicon vertex detector of the Belle II experiment Gabrielli, A.; Adamczyk, K.; Aihara, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
Recenzirano
The silicon vertex detector (SVD) is a four-layer double-sided strip detector installed at the heart of the Belle II experiment, taking data at the high-luminosity B-Factory SuperKEKB since 2019. SVD ...has been operating smoothly and reliably, showing a stable and above-99% hit efficiency, and a large signal-to-noise ratio in all sensors. In June 2022 the data-taking of the Belle II experiment was stopped for the Long Shutdown 1, primarily required to complete the vertex detector (VXD) with the inner two-layer DEPFET detector and to upgrade several components of the accelerator. This article reports on the excellent performance of SVD in terms of the signal-to-noise ratio, the hit position resolution, as well as the hit-time resolution. We briefly describe the challenges and delicate phases of the VXD re-installation and the SVD status for operation starting in early 2024. In SVD layer 3, which is closest to the interaction point, the average occupancy has been less 0.5%, well below the estimated limit for acceptable tracking performance. However, higher machine backgrounds are expected at increased luminosity, and so also increased hit occupancy. To enhance the robustness of offline software in a high-background environment, new algorithms of background suppression using the excellent SVD hit-time information have been developed, which allows a significant reduction of the fake rate, while preserving the tracking efficiency.
With the increasing luminosity also the radiation levels are expected to increase, with possible deterioration of the sensor performance. The SVD integrated dose is estimated by the correlation of the SVD occupancy with the dose rate measured by the diamonds of the radiation monitor and beam-abort system.
The effects of radiation damage are starting and in good agreement with our expectations. So far, no harmful impact due to the radiation damage on the detector performance has been observed.
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