Search for Dark-Matter-Nucleon Interactions via Migdal Effect with DarkSide-50

Dark matter elastic scattering off nuclei can result in the excitation and ionization of the recoiling atom through the so-called Migdal effect. The energy deposition from the ionization electron adds to the energy deposited by the recoiling nuclear system and allows for the detection of interactions of sub-GeV/c^{2} mass dark matter. We present new constraints for sub-GeV/c^{2} dark matter using the dual-phase liquid argon time projection chamber of the DarkSide-50 experiment with an exposure of (12 306±184)  kg d. The analysis is based on the ionization signal alone and significantly enhances the sensitivity of DarkSide-50, enabling sensitivity to dark matter with masses down to 40  MeV/c^{2}. Furthermore, it sets the most stringent upper limit on the spin independent dark matter nucleon cross section for masses below 3.6  GeV/c^{2}.

Search for Dark Matter Particle Interactions with Electron Final States with DarkSide-50

We present a search for dark matter particles with sub-GeV/c^{2} masses whose interactions have final state electrons using the DarkSide-50 experiment's (12 306±184)  kg d low-radioactivity liquid argon exposure. By analyzing the ionization signals, we exclude new parameter space for the dark matter-electron cross section σ[over ¯]_{e}, the axioelectric coupling constant g_{Ae}, and the dark photon kinetic mixing parameter κ. We also set the first dark matter direct-detection constraints on the mixing angle |U_{e4}|^{2} for keV/c^{2} sterile neutrinos.

The novel Mechanical Ventilator Milano for the COVID-19 pandemic

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

Constraints on Sub-GeV Dark-Matter-Electron Scattering from the DarkSide-50 Experiment

We present new constraints on sub-GeV dark-matter particles scattering off electrons based on 6780.0 kg d of data collected with the DarkSide-50 dual-phase argon time projection chamber. This analysis uses electroluminescence signals due to ionized electrons extracted from the liquid argon target. The detector has a very high trigger probability for these signals, allowing for an analysis threshold of three extracted electrons, or approximately 0.05 keVee. We calculate the expected recoil spectra for dark matter-electron scattering in argon and, under the assumption of momentum-independent scattering, improve upon existing limits from XENON10 for dark-matter particles with masses between 30 and 100  MeV/c^{2}.

Low-Mass Dark Matter Search with the DarkSide-50 Experiment

We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20  GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1  keVee. The observed rate in the detector at 0.5  keVee is about 1.5  event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8  GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6  GeV/c^{2}.

Superior Vena Cava Thrombosis after Intravascular AICD Lead Extraction: A Case Report

Pacemaker lead extraction has been shown to be an effective and safe treatment in the case of infected permanent pacemaker leads. However, it can lead to potentially serious complications, usually occurring during the extraction procedure. This report describes a case of a 74-year-old male with a persistent superior vena cava thrombosis related to an infected permanent pacemaker lead transvenous extraction. Clinical and surgical management are discussed.

Serum leptin and CD4+ T lymphocytes in HIV+ children during highly active antiretroviral therapy

OBJECTIVE

Because leptin, the adipocyte-derived hormone, affects thymocyte survival, proliferation of naïve T lymphocytes and the production of proinflammatory cytokines, we aimed to investigate the role of this molecule in immunoreconstitution during highly active antiretroviral therapy (HAART).

DESIGN

Prospective longitudinal cohort study. A series of 20 HIV+ children were studied. The subjects were grouped by their increase in serum leptin levels after HAART.

METHODS

All participants were weight-stable, free of endocrine disorders and opportunistic infections and equally distributed for sex (males, n=10; females, n=10). Body mass index (BMI), serum lipids, leptin, CD4+ T cells and HIV-1 RNA were measured before initiation of HAART and after a 2-year follow-up.

RESULTS

Serum leptin concentration positively correlated with CD4+ lymphocyte number before treatment. HAART significantly reduced viraemia and increased serum levels of lipids in all patients, whereas a significant increase in CD4+ cells and serum leptin was observed in the majority of patients. Notably, in children where HAART was not effective in increasing CD4+ lymphocyte counts, serum leptin did not increase.

CONCLUSION

To our knowledge, these findings reveal for the first time a novel link among CD4+ T lymphocytes, serum leptin and highly active anteretroviral theraphy.

The acute effect of smoking on cutaneous microcirculation blood flow in habitual smokers and nonsmokers

BACKGROUND

Smoking is known to be a primary cause of chronic harmful effects on the vascular system. It also induces some acute effects on the coronary circulation and on the ophthalmic artery.

OBJECTIVE

The aim of our study was to assess the effect of smoking a single cigarette on cutaneous blood flow in habitual smokers as well as in nonsmokers.

METHODS

A laser Doppler flowmeter was used to perform measurements of cutaneous microcirculation. Flowmetric data were recorded (i) before smoking, (ii) inhaling from an unlighted cigarette, (iii) during cigarette smoking, (iv) 2 and (v) 5 min after smoking.

RESULTS

We could show that smoking a single cigarette acts on the cutaneous microcirculation reducing blood flow in both groups of subjects (38.1% reduction in smokers and 28.1% reduction in nonsmokers; p <0.01). Interestingly, the recovery phase is faster in nonsmoker subjects than in smoker ones; in fact, the recovery is complete 2 and 5 min after cigarette smoking in nonsmokers and in smokers, respectively.

CONCLUSION

Smoking a single cigarette decreases the cutaneous blood flow in habitual smoker as well as in nonsmoker subjects. Moreover, the slower recovery phase of smokers suggests that their microcirculation become inured to smoke.