941 research outputs found
A Unique Multi-Messenger Signal of QCD Axion Dark Matter
We propose a multi-messenger probe of QCD axion Dark Matter based on
observations of black hole-neutron star binary inspirals. It is suggested that
a dense Dark Matter spike may grow around intermediate mass black holes
(). The presence of such a spike produces
two unique effects: a distinct phase shift in the gravitational wave strain
during the inspiral and an enhancement of the radio emission due to the
resonant axion-photon conversion occurring in the neutron star magnetosphere
throughout the inspiral and merger. Remarkably, the observation of the
gravitational wave signal can be used to infer the Dark Matter density and,
consequently, to predict the radio emission. We study the projected reach of
the LISA interferometer and next-generation radio telescopes such as the Square
Kilometre Array. Given a sufficiently nearby system, such observations will
potentially allow for the detection of QCD axion Dark Matter in the mass range
to .Comment: 5 pages, 3 figures. Appendix added with additional figures. Updated
to published versio
CleAir monitoring system for particulate matter. A case in the Napoleonic Museum in Rome
Monitoring the air particulate concentration both outdoors and indoors is becoming a more relevant issue in the past few decades. An innovative, fully automatic, monitoring system called CleAir is presented. Such a system wants to go beyond the traditional technique (gravimetric analysis), allowing for a double monitoring approach: the traditional gravimetric analysis as well as the optical spectroscopic analysis of the scattering on the same filters in steady-state conditions. The experimental data are interpreted in terms of light percolation through highly scattering matter by means of the stretched exponential evolution. CleAir has been applied to investigate the daily distribution of particulate matter within the Napoleonic Museum in Rome as a test case
Decaying Leptophilic Dark Matter at IceCube
We present a novel interpretation of IceCube high energy neutrino events
(with energy larger than 60 TeV) in terms of an extraterrestrial flux due to
two different contributions: a flux originated by known astrophysical sources
and dominating IceCube observations up to few hundreds TeV, and a new flux
component where the most energetic neutrinos come from the leptophilic
three-body decays of dark matter particles with a mass of few PeV. Differently
from other approaches, we provide two examples of elementary particle models
that do not require extremely tiny coupling constants. We find the
compatibility of the theoretical predictions with the IceCube results when the
astrophysical flux has a cutoff of the order of 100 TeV (broken power law). In
this case the most energetic part of the spectrum (PeV neutrinos) is due to an
extra component such as the decay of a very massive dark matter component. Due
to the low statistics at our disposal we have considered for simplicity the
equivalence between deposited and neutrino energy, however such approximation
does not affect dramatically the qualitative results. Of course, a purely
astrophysical origin of the neutrino flux (no cutoff in energy below the PeV
scale - unbroken power law) is still allowed. If future data will confirm the
presence of a sharp cutoff above few PeV this would be in favor of a dark
matter interpretation.Comment: 19 pages, 3 figures. Version published in JCAP. The analysis was
performed in terms of the number of neutrino events instead of the neutrino
flux, using a multi-Poisson likelihood approac
Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations
The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 105 and 109 GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission
Toxicological Impact of Rare Earth Elements (REEs) on the Reproduction and Development of Aquatic Organisms Using Sea Urchins as Biological Models
The growing presence of lanthanides in the environment has drawn the attention of the scientific community on their safety and toxicity. The sources of lanthanides in the environment include diagnostic medicine, electronic devices, permanent magnets, etc. Their exponential use and the poor management of waste disposal raise serious concerns about the quality and safety of the ecosystems at a global level. This review focused on the impact of lanthanides in marine organisms on reproductive fitness, fertilization and embryonic development, using the sea urchin as a biological model system. Scientific evidence shows that exposure to lanthanides triggers a wide variety of toxic insults, including reproductive performance, fertilization, redox metabolism, embryogenesis, and regulation of embryonic gene expression. This was thoroughly demonstrated for gadolinium, the most widely used lanthanide in diagnostic medicine, whose uptake in sea urchin embryos occurs in a time-and concentration-dependent manner, correlates with decreased calcium absorption and primarily affects skeletal growth, with incorrect regulation of the skeletal gene regulatory network. The results collected on sea urchin embryos demonstrate a variable sensitivity of the early life stages of different species, highlighting the importance of testing the effects of pollution in different species. The accumulation of lanthanides and their emerging negative effects make risk assessment and consequent legislative intervention on their disposal mandatory
Linear conduction in N-type organic field effect transistors with nanometric channel lengths and graphene as electrodes
In this work, we test graphene electrodes in nanometric channel n-type Organic Field Effect Transistors (OFETs) based on thermally evaporated thin films of the perylene-3,4,9,10-tetracarboxylic acid diimide derivative. By a thorough comparison with short channel transistors made with reference gold electrodes, we found that the output characteristics of the graphene-based devices respond linearly to the applied bias, in contrast with the supralinear trend of gold-based transistors. Moreover, short channel effects are considerably suppressed in graphene electrode devices. More specifically, current on/off ratios independent of the channel length (L) and enhanced response for high longitudinal biases are demonstrated for L down to 3c140 nm. These results are rationalized taking into account the morphological and electronic characteristics of graphene, showing that the use of graphene electrodes may help to overcome the problem of Space Charge Limited Current in short channel OFETs
Protein polymorphisms and coagulation properties of Cilentana goat milk
The study was carried out on 86 ‘Cilentana’ goats, distributed in four herds. Milk samples were collected during morning and evening milking, and pH, dry matter, fat, protein and lactose percentage as well as the lactodynamometric profile were detected to determine enzymatic phase duration, coagulation speed and curd consistency. Polymorphism of the s1-casein protein was detected. Four alleles (designated A, B, E and F) and nine genotypes were detected. The association of these nine genotypes with chemical composition and lactodynamometric characteristics was investigated. The BF genotype was the most frequent (35.5 %), followed by EE (15.1 %) and AF and BB (10.4%). The F allele showed the highest frequency and it negatively influenced cheesemaking as it was associated with a low s1-casein content. Goats with the AB genotype produced milk with higher dry matter, protein and fat content compared with the FF genotype. Moreover, milk from the AB genotype has a lower enzymatic phase duration and a higher coagulation speed than the BB genotype. Curd consistency is higher for milk from the AA genotype, when compared with the EF genotype. All the chemical and lactodynamometric characteristics varied with herd and months of control; furthermore, the milk obtained from morning milking showed better coagulation properties
Robust Limits from Upcoming Neutrino Telescopes and Implications on Minimal Dark Matter Models
Experimental developments in neutrino telescopes are drastically improving
their ability to constrain the annihilation cross-section of dark matter. In
this paper, we employ an angular power spectrum analysis method to probe the
galactic and extra-galactic dark matter signals with neutrino telescopes. We
first derive projections for a next generation of neutrino telescope that is
inspired by KM3NeT. We emphasise that such analysis is much less sensitive to
the choice of dark matter density profile. Remarkably, the projected
sensitivity is improved by more than an order of magnitude with respect to the
existing limits obtained by assuming the Burkert dark matter density profile
describing the galactic halo. Second, we analyse minimal extensions to the
Standard Model that will be maximally probed by the next generation of neutrino
telescopes. As benchmark scenarios, we consider Dirac dark matter in - and
-channel models with vector and scalar mediators. We follow a global
approach by examining all relevant complementary experimental constraints. We
find that neutrino telescopes will be able to competitively probe significant
portions of parameter space. Interestingly, the anomaly-free
model can potentially be explored in regions where the relic abundance is
achieved through freeze-out mechanism
Evaluating the use of graphene electrodes in sub-micrometric, high-frequency n-type organic transistors
In this work we report on fully operational sub-micrometric low voltage OFETs by using graphene as the source-drain electrodes pair and a high-κ ultra-thin dielectric in a local gate architecture. The impact of the graphene electrodes on the miniaturization of the organic devices has been assessed, with particular attention to the influence of the contact resistances as well as the parasitic overlap gate capacitance on the device bandwidth. By the use of a modified Transmission-Line-Method, contact resistances have been analyzed as function of the applied voltages, revealing characteristic functional trends that follow the doping state of graphene electrodes. Through impedance spectroscopy of the electrodes, cut-off frequencies as high as 105 Hz have been estimated, highlighting the peculiar role of quantum capacitance of graphene in such architectures
Effect of beetroot (Beta vul-garis) extract on black angus burgers shelf life
Beef burgers are meat preparations with easy perishability. To ensure a longer shelf-life, the Regulation EU 1129/11 allows the use of some additives. However, health-conscious consumers prefer products which do not contain synthetic substances. Aim of the present study was to evaluate the effect of Red Beetroot (Beta vulgaris) integration on Black Angus made burgers shelf life. Red beet was prepared as powder and added to meat mixture as the same or in water solution. The study was split into 2 trials to assess the extract activity also in burgers vacuum-packaged stored. Burgers were analysed (up to 9 days at 4°C) in terms of sensory properties, microbiological profile, pH, aw and lipid oxidation (TBARS). At the end of storage, treated samples showed the highest values of redness and the lowest content of malondialdehyde, probably due to antioxidant properties of red beet towards myoglobin and lipid oxidation processes. Moreover, results highlighted that Red Beetroot activities were dose-dependent and intensified if dissolved in water. The aw values did not appear to be conditioned by extract integrations, unlike the pH that was lower in treated samples than control ones. Microbiological analyses identified beet-root as a potential antimicrobial substance, especially in high concentration. In conclusion, Beta vulgaris extract could be pro-posed as natural compound exploitable in beef burgers to preserve qualities and extend their shelf-life
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