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.

Recoil Directionality Experiment

Directional sensitivity to nuclear recoils could provide a smoking gun for a possible discovery of dark matter in the form of WIMPs. A hint of directional dependence of the response of a dual-phase liquid argon Time Projection Chamber was found in the SCENE experiment. Given the potential importance of such a capability in the frame work of dark matter searches, a new dedicated experiment, ReD (Recoil Directionality), was designed in the framework of the DarkSide Collaboration, in order to scrutinize this hint. This contribution will describe the performance of the detectors achieved during the first test-beam, the current status of ReD and the perspectives for physics measurements during the forthcoming beam-time.

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}.

Validity of a short insomnia questionnaire: the SDQ

The SDQ is a brief self-report insomnia questionnaire, which permits the rapid evaluation of insomnia based on the DSM-IV and ICSD-R criteria. The SDQ was developed to provide a fast and valid instrument both for the pre-screening of subjects who complain of insomnia and for epidemiological studies based on standardized definitions of this sleep disorder. Two studies were carried out in order to assess the validity of the SDQ as a self-report measure of insomnia. In the first study the convergent validity of the SDQ was assessed with respect to the global score of the Pittsburgh Sleep Quality Index (PSQI) in a sample of general practitioners' patients. The second study assessed the sensitivity and the specificity of the SDQ in discriminating between insomniacs or normal sleepers in a sample of college students who were given an extensive sleep evaluation within an insomnia counseling program. The SDQ classifications have a good convergent validity with the global sleep quality scores of the PSQI and its classifications of students who complain of or who do not complain of problems of insomnia have a sensitivity of 95% and a specificity of 87%. Results indicate that the SDQ is a valid paper and pencil instrument to screen insomnia.

The assessment of daytime sleep propensity: a comparison between the Epworth Sleepiness Scale and a newly developed Resistance to Sleepiness Scale

INTRODUCTION

The Epworth sleepiness scale (ESS) is widely used as a way of measuring subjective sleep propensity in research and clinical practice. Psychometric studies do not rule out the presence of more than one latent dimension underlying the items.

OBJECTIVE

Aims of the present study were to: (a) evaluate psychometric proprieties of the ESS by means of classic psychometric techniques; (b) compare them with those from a newly developed resistance to sleepiness scale (RSS); (c) evaluate, following the latent trait theory, whether the items of both ESS and RSS could be conceptualized as different levels of an interval variable representative of a single latent trait related to sleep propensity.

METHODS

One hundred and forty-six inpatients suffering from different sleep disorders filled in both the RSS and ESS in a sleep disorder centre.

RESULTS

Indexes of fit derived by the application of the extended logistic model are consistent with the idea that each ESS item can be conceptualized as different levels of an interval variable representative of a single latent trait. However, most of the ESS items are found to be located at the opposite extremes of this continuum.

CONCLUSIONS

The under representation of situations characterized by an intermediate soporific nature in the ESS could limit ESS sensitivity to detect intermediate variations of sleep propensity.

Bis-indols: a novel class of molecules enhancing the cytodifferentiating properties of retinoids in myeloid leukemia cells

Enhancing the pharmacologic activity of all-trans retinoic acid (ATRA) is potentially useful in the management of acute promyelocytic leukemia (APL) and other types of myeloid leukemia. In this report, we identify a novel class of experimental agents selectively potentiating the cytodifferentiating activity of ATRA and synthetic retinoic acid receptor alpha agonists in APL and other myeloid leukemia cell lines. These agents have a bis-indolic structure (BISINDS), and ST1346 is the prototypical compound of the series. Gene-profiling experiments and determination of the level of expression of myeloid-associated markers indicate that ST1346 stimulates many aspects of the granulocytic maturation process set in motion by ATRA. Stimulation of the cytodifferentiating activity of ATRA by ST1346 enhances the efficacy of the retinoid in vivo, as demonstrated in the APL model of the severe combined immunodeficiency (SCID) mouse receiving transplants of NB4 cells. Although the molecular mechanisms underlying the ATRA-potentiating action of ST1346 and congeners have not been completely clarified, bis-indols are not ligands and do not exert any direct effect on the ATRA-dependent transactivation of nuclear receptors. However, ST1346 inhibits the down-regulation of cyclic adenosine monophosphate (cAMP)-dependent CREB transcriptional complexes and enhances the level of expression of signal transducers and activators of transcription-1 (STAT1), 2 putative molecular determinants of the differentiation process activated by ATRA in APL cells. More importantly, ST1346 relieves the down-regulation of Jun N-terminal kinases (JNK) afforded by ATRA. In addition, a specific JNK inhibitor blocks the enhancing effect of ST1346 on ATRA-induced maturation of NB4 cells. This demonstrates an important role for the mitogen-activated protein kinase in the molecular mechanisms underlying the pharmacologic activity of the bis-indol.

Three unique mutants of Arabidopsis identify eds loci required for limiting growth of a biotrophic fungal pathogen

To identify components of the defense response that limit growth of a biotrophic fungal pathogen, we isolated Arabidopsis mutants with enhanced disease susceptibility to Erysiphe orontii. Our initial characterization focused on three mutants, eds14, eds15, and eds16. None of these is considerably more susceptible to a virulent strain of the bacterial pathogen Pseudomonas syringae pv. maculicola (Psm). All three mutants develop a hypersensitive response when infiltrated with Psm expressing the avirulence gene avrRpt2, which activates resistance via the LZ-NBS/LRR resistance protein encoded by RPS2. The growth of Psm(avrRpt2), while somewhat greater in the mutants than in the wild type, is less than growth of the isogenic virulent strain. These results indicate that resistance mediated via LZ-NBS/LRR R genes is functional. Analysis of the growth of avirulent Peronospora parasitica strains showed that the resistance pathway utilized by TIR-NBS/LRR R genes is also operative in all three mutants. Surprisingly, only eds14 and eds16 were more susceptible to Erysiphe cichoracearum. Analysis of the expression profiles of PR-1, BGL2, PR-5 and PDF1.2 in eds14, eds15, and eds16 revealed differences from the wild type for all the lines. In contrast, these mutants were not significantly different from wild type in the deposition of callose at sites of E. orontii penetration. All three mutants have reduced levels of salicylic acid after infection. eds16 was mapped to the lower arm of chromosome I and found by complementation tests to be allelic to the salicylic acid-deficient mutant sid2.

Topology, subcellular localization, and sequence diversity of the Mlo family in plants

Barley Mlo defines the founder of a novel class of plant integral membrane proteins. Lack of the wild type protein leads to broad spectrum disease resistance against the pathogenic powdery mildew fungus and deregulated leaf cell death. Scanning N-glycosylation mutagenesis and Mlo-Lep fusion proteins demonstrated that Mlo is membrane-anchored by 7 transmembrane (TM) helices such that the N terminus is located extracellularly and the C terminus intracellularly. Fractionation of leaf cells and immunoblotting localized the protein to the plant plasma membrane. A genome-wide search for Mlo sequence-related genes in Arabidopsis thaliana revealed approximately 35 family members, the only abundant gene family encoding 7 TM proteins in higher plants. The sequence variability of Mlo family members within a single species, their topology and subcellular localization are reminiscent of the most abundant class of metazoan 7 TM receptors, the G-protein-coupled receptors.

Defence signalling pathways in cereals

The combination of mutational and molecular studies has shed light on the role of reactive oxygen intermediates and programmed cell death in cereal disease resistance mechanisms. Rice Rac1 and barley Rar1 represent conserved disease resistance signalling genes, which may have related functions in animals. The analysis of non-pathogenic Magnaporthe grisea mutants may provide novel tools to study host defence pathways.

Effects of different sleep reductions on daytime sleepiness

This study evaluated the effects of different amounts of sleep and SWS restriction on the ensuing day-time sleepiness. Six healthy selected males, after one adaptation night and an initial 8-hr baseline night, were allowed to sleep 5, 4, 3, 2, and 1 hr with a 1-week interval between conditions. The following day, 4 sleep onset MSLT trials and 2 Wilkinson Auditory Vigilance Task (WAVT) were administered. Before each MSLT, self evaluations of sleepiness and activation on a visual analogue scale (ADAS) were assessed. Each restriction night was followed by an 8-hr recovery night, and a final 8-hr baseline night was recorded. The day after each night the same diurnal tests were repeated. Results indicated a linear increase in the propensity to sleep (MSLT) and of subjective sleepiness as a function of the increase in sleep restrictions. Performance scores (WAVT) showed that vigilance is partially affected by sleep restrictions. For each measure, regression analyses showed that the effect of sleep reduction is better predicted by the total duration of sleep than by the amount of SWS. Correlations between measures were negligible with the exception of those between performance and subjective sleepiness measures.

The promoter of a gene encoding a polygalacturonase-inhibiting protein of Phaseolus vulgaris L. is activated by wounding but not by elicitors or pathogen infection

Polygalacturonase-inhibiting proteins (PGIPs), leucine-rich repeat (LRR) proteins evolutionarily related to several plant resistance genes, bind to and regulate the action of fungal endopolygalacturonases. In Phaseolus vulgaris L., PGIPs are encoded by a gene family comprising at least five members. As a start for a systematic analysis of the regulation of the pgip family, we have analysed the ability of the promoter of the bean gene pgip-1 to direct expression of beta-glucuronidase (GUS) in transfected tobacco protoplasts, microbombarded bean and tobacco leaves, and transgenic tobacco plants. In protoplasts, the pgip-1 gene region from nucleotide (nt) -2004 to nt +27 directed a level of expression that was as high as that directed by the cauliflower mosaic virus (CaMV) 35S promoter and could not be further induced by elicitor treatment; alteration of the region immediately following the TATAA sequence at nt -29 abolished expression. Upon stable integration into tobacco plants of the pgip-1 promoter-GUS construct, as well as of a -394 deletion, expression was detected for both constructs mainly in the stigma and, to a lesser extent, in the anthers and in the conductive vascular tissue. The promoter responded to wounding but not to oligogalacturonides, fungal glucan, salicylic acid, cryptogein, or pathogen infection. This expression pattern does not mirror that of the whole pgip gene family.

Effects of different sleep duration on delta sleep in recovery nights

The study assessed the effects of different amounts of sleep restriction on slow wave sleep (SWS) in the ensuing recovery nights. After one adaptation night and an 8-hr baseline night, six healthy men were individually studied during and following five nights in which sleep was reduced to 5, 4, 3, 2, and 1 hr with a 1-week interval between conditions. Each sleep reduction was followed by an 8-hr recovery night. Finally, a second 8-hr baseline night was recorded. A trend analysis revealed that SWS amount in recovery nights increases with decreasing previous sleep duration. Regression analyses showed that, within each participant, the rebound of SWS after a sleep reduction is predicted better by the total duration of sleep than by the specific amount of SWS lost.

Rapid eye movements density as a measure of sleep need: REM density decreases linearly with the reduction of prior sleep duration

In the recovery nights from total and partial sleep deprivation there is a reduction of oculomotor activity during paradoxical sleep as compared to baseline nights. Aims of the present within-subjects study are to contribute in understanding the nature of the relationship between REM density and sleep need and to evaluate whether an inverse relationship exists between REM density and slow wave sleep (SWS) amount. Six healthy subjects were studied for 7 consecutive weeks with standard polysomnographic recordings. Variations in REM density were assessed in the recovery nights following a gradual sleep restriction, obtained by postponing the sleep onset time while maintaining the final awakening time constant. Results indicate that sleep curtailment decreases REM density in the ensuing recovery nights; the decrease is linearly related to the amount of sleep curtailment. The decrease in REM density parallels an increase in SWS, while no corresponding variation was found neither in the duration of paradoxical sleep nor in the latency of any other sleep stage. These results suggest that REM density could be used as a measure of sleep need.

Left movers' advantage in heartbeat discrimination: a replication and extension

Lateral eye movers are subjects who consistently shift their gaze either leftward or rightward while reflecting on visuospatial or verbal questions. When reliably assessed, prevalent direction of gaze can be assumed as a valid index of hemispheric asymmetry. The present study evaluated discrimination of heartbeat (HB) and of spontaneous changes of finger temperature in 24 right-handed females reliably selected as lateral movers. Results replicate and extend previous findings by showing that left movers' superiority in HB discrimination is present also in females and concerns the perception of a different vascular function, that is, peripheral finger temperature. Differences between right movers and left movers were not due to activation level during the test or to body composition.