1,600 research outputs found
Absence of Superfluidity in 2D Dipolar Bose Striped Crystals
We present results of computer simulations at low temperature of a
two-dimensional system of dipolar bosons, with dipole moments aligned at an
arbitrary angle with respect to the direction perpendicular to the plane. The
phase diagram includes a homogeneous superfluid phase, as well as triangular
and striped crystalline phases, as the particle density and the tilt angle are
varied. In the striped solid, no phase coherence among stripes and consequently
no ``supersolid" phase is found, in disagreement with recent theoretical
predictions.Comment: Accepted for publication as a Rapid Communication in the Journal of
Low Temperature Physic
A superfluid-droplet crystal and a free-space supersolid in a dipole-blockaded gas
A novel supersolid phase is predicted for an ensemble of Rydberg atoms in the
dipole-blockade regime, interacting via a repulsive dipolar potential
"softened" at short distances. Using exact numerical techniques, we study the
low temperature phase diagram of this system, and observe an intriguing phase
consisting of a crystal of mesoscopic superfluid droplets. At low temperature,
phase coherence throughout the whole system, and the ensuing bulk
superfluidity, are established through tunnelling of identical particles
between neighbouring droplets.Comment: 4 pages, 4 figure
Electrochemical biosensors for tracing cyanotoxins in food and environmental matrices
The adoption of electrochemical principles to realize on-field analytical tools for detecting pollutants represents a great possibility for food safety and environmental applications. With respect to the existing transduction mechanisms, i.e., colorimetric, fluorescence, piezoelectric etc., electrochemical mechanisms offer the tremendous advantage of being easily miniaturized, connected with low cost (commercially available) readers and unaffected by the color/turbidity of real matrices. In particular, their versatility represents a powerful approach for detecting traces of emerging pollutants such as cyanotoxins. The combination of electrochemical platforms with nanomaterials, synthetic receptors and microfabrication makes electroanalysis a strong starting point towards decentralized monitoring of toxins in diverse matrices. This review gives an overview of the electrochemical biosensors that have been developed to detect four common cyanotoxins, namely microcystin-LR, anatoxin-a, saxitoxin and cylindrospermopsin. The manuscript provides the readers a quick guide to understand the main electrochemical platforms that have been realized so far, and the presence of a comprehensive table provides a perspective at a glance
Corrigendum to "Co-seismic surface effects from very high resolution panchromatic images: the case of the 2005 Kashmir (Pakistan) earthquake" published in Nat. Hazards Earth Syst. Sci., 11, 931–943, 2011
No abstract available
Hard X-ray polarimetry using scintillators
The linear polarization of the radiation from celestial sources can be investigated by studying the angular distribution of Compton scattered photons in a detection device. In this contribution we present the design of a Compton polarimeter based on the technology of fiber-shaped scintillators. A total geometric area of 1000 cm2 or more could be obtained by repeating a basic polarimeter composed by several fiber-like scintillators, some of them of low Z, acting as active scatterers, and others of high Z, acting as detectors. Polarimetric measurements can thus be carried out by searching for coincidences between a scatterer fiber and an absorber one. Monte Carlo simulations of the performances of such a device, when employed onboard a stratospheric balloon, are compared with other kinds of X-ray polarimeters
The case of the 2005 Kashmir earthquake
The use of Very High Resolution (VHR) satellite
panchromatic image is nowadays an effective tool to
detect and investigate surface effects of natural disasters.
We specifically examined the capabilities of VHR images
to analyse earthquake features and detect changes based on
the combination of visual inspection and automatic classification
tools. In particular, we have used Quickbird (0.6m
spatial resolution) images for detecting the three main coseismic
surface features: damages, ruptures and landslides.
The present approach has been applied to the 8 October 2005,
Mw7.6 Kashmir, Pakistan, earthquake. We have focused our
study in and around the main urban areas hit by the above
earthquake specifically at Muzaffarabad and Balakot towns.
The automatic classification techniques provided the best results
wherever dealing with the damage to man-made structures
and landslides. On the other hand, the visual inspection
method demonstrated in addressing the identification of
rupture traces and associated features. The synoptic view
(concerning landslide, more than 190 millions of pixels have
been automatically classified), the spatiotemporal sampling
and the fast automatic damage detection using satellite images
provided a reliable contribution to the prompt response
during natural disaster and for the evaluation of seismic hazard
as well
Broad band X-ray spectral properties of Gamma-ray bursts with BeppoSAX
In about one year, five gamma-ray bursts were simultaneously observed with
the Wide Field Cameras and Gamma Ray Burst Monitor aboard the BeppoSAX
satellite. From some of them X-ray afterglow emission has been clearly detected
with the same satellite. In order to understand how GRB emission is related to
the X-ray afterglow, we are performing a systematic study of the spectral
properties of these events. We report here preliminary results of this study.Comment: 5 pages, 3 figures. To appear in the Proceedings of the 4th
Huntsville Gamma-ray Burst Symposiu
A Hybrid Screen-Printed Strip for Enhanced Electroanalysis towards Lead and Cadmium in Multi-Matrices
Although heavy metals represent a major treat for ecosystem and human health, reference methods for their monitoring are characterized by time-consuming procedures, skilled personel and sophisticated equipment (e.g. ICP-MS, AAS). The development of portable solutions is required, particularly improving interventions and reducing complexity. To this regards, an electrochemical strip for the determination of lead and cadmium in clinical, environmental and food matrices have been developed. The Bismuth film-based flexible device has been optimized and it has been able to detect cadmium and lead, respectively, down to the detection limit of 1.3 and 2 ppb. The use of Whatman No.1 chromatographic paper has allowed to improve the sensitivity towards the detection of heavy metals, because of the porosity that allowed to pre-concentrate species. This led to an improvement in the sensitivity, with a detection limit of 0.3 and 0.5 ppb, respectively, to cadmium and lead, and offers the possibility to tune the sensitivity according to needs, e.g., improving the number of pre-concentration steps. Subsequently, the application of the electrochemical sensor in drinking water, mussel and blood serum was evaluated, demonstrating how these hybrid polyester-paper electrochemical strips can significantly lower the time and costs for on-site measurements, through analytical methods of simple use. The accuracy has been evaluated by comparison with ICP-MS measurements, giving satisfactory results
Bioarchaeological and paleogenomic profiling of the unusual Neolithic burial from Grotta di Pietra Sant’Angelo (Calabria, Italy)
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