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.

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}.

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}.

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 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.

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.

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.

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.

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.

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.

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.

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.