2,126 research outputs found
Quantum characterization of bipartite Gaussian states
Gaussian bipartite states are basic tools for the realization of quantum
information protocols with continuous variables. Their complete
characterization is obtained by the reconstruction of the corresponding
covariance matrix. Here we describe in details and experimentally demonstrate a
robust and reliable method to fully characterize bipartite optical Gaussian
states by means of a single homodyne detector. We have successfully applied our
method to the bipartite states generated by a sub-threshold type-II optical
parametric oscillator which produces a pair of thermal cross-polarized
entangled CW frequency degenerate beams. The method provide a reliable
reconstruction of the covariance matrix and allows to retrieve all the physical
information about the state under investigation. These includes observable
quantities, as energy and squeezing, as well as non observable ones as purity,
entropy and entanglement. Our procedure also includes advanced tests for
Gaussianity of the state and, overall, represents a powerful tool to study
bipartite Gaussian state from the generation stage to the detection one
Revealing microbial recognition by specific antibodies
Background:
Recognition of microorganisms by antibodies is a vital component of the human immune response. However, there is currently very limited understanding of immune recognition of 50 % of the human microbiome which is made up of as yet un-culturable bacteria. We have combined the use of flow cytometry and pyrosequencing to describe the microbial composition of human samples, and its interaction with the immune system.
Results:
We show the power of the technique in human faecal, saliva, oral biofilm and breast milk samples, labeled with fluorescent anti-IgG or anti-IgA antibodies. Using Fluorescence-Activated Cell Sorting (FACS), bacterial cells were separated depending on whether they are coated with IgA or IgG antibodies. Each bacterial population was PCR-amplified and pyrosequenced, characterizing the microorganisms which evade the immune system and those which were recognized by each immunoglobulin.
Conclusions:
The application of the technique to healthy and diseased individuals may unravel the contribution of the immune response to microbial infections and polymicrobial diseases
Benchmark of Atucha-2 PHWR RELAP5-3D Control Rod Model by Monte Carlo MCNP5 Core Calculation
Atucha-2 is a Siemens-designed PHWR reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarities require the adoption of
advanced Monte Carlo codes for performing realistic neutronic simulations. Therefore core models of Atucha-2 PHWR were developed using MCNP5. In this work a
methodology was set up to collect the flux in the hexagonal mesh by which the Atucha-2 core is represented. The scope of this activity is to evaluate the effect of
obliquely inserted control rod on neutron flux in order to validate the RELAP5-3DC/NESTLE three dimensional neutron kinetic coupled thermal-hydraulic model, applied by
GRNSPG/UNIPI for performing selected transients of Chapter 15 FSAR of Atucha-2
Couplings of N=1 chiral spinor multiplets
We derive the action for chiral spinor multiplets coupled to vector and
scalar multiplets. We give the component form of the action, which contains
gauge invariant mass terms for the antisymmetric tensors in the spinor
superfield and additional Green-Schwarz couplings to vector fields. We observe
that supersymmetry provides mass terms for the scalars in the spinor multiplet
which do not arise from eliminating an auxiliary field. We construct the dual
action by explicitly performing the duality transformations in superspace and
give its component form.Comment: 17 pages, v2 small change
M/M/ queues in semi-Markovian random environment
In this paper we investigate an M/M/ queue whose parameters depend on
an external random environment that we assume to be a semi-Markovian process
with finite state space. For this model we show a recursive formula that allows
to compute all the factorial moments for the number of customers in the system
in steady state. The used technique is based on the calculation of the raw
moments of the measure of a bidimensional random set. Finally the case when the
random environment has only two states is deeper analyzed. We obtain an
explicit formula to compute the above mentioned factorial moments when at least
one of the two states has sojourn time exponentially distributed.Comment: 17 pages, 2 figure
The April-May 2006 volcano-tectonic events at Stromboli volcano (Southern Italy) and their relation with the magmatic system.
Between April 10th and May 22th 2006, a small seismic swarm of 5 volcano-tectonic events occurred on the volcanic island of Stromboli (Southern Italy). Two of these, having M > 3 and an intensity of about V-VI MCS, were clearly felt causing concern in the population. They were recorded during a period of increased explosive activity and were followed by two major explosions at the summit craters on May 22th, few hours after the last earthquake and on 16th June. The location of such events has been performed using a probabilistic approach based on the Equal Differential Time tecnique. Using this tecnique, we were able to locate all the events, showing how they cluster below the volcanic edifice at a depth of about 5Ă·6 km. From observed P wave polarities we determined the focal mechanisms of the 4 major events. Using earthquake scaling nlaws, we calculated the fault area and the average slip for the two major events. Finally, assuming an homogeneous half-space model we computed the isotropic stress changes below the volcano edifice. The negative stress variation over the central axis of the volcano suggests that the earthquakes
were triggered by a pressurization of the magmatic system
10th September 2005: a bolide airblast in the Gulf of Naples (Southern Italy).
On 10th September 2005 at 17:11 local time (15:11 GMT) a loud boom was heard on the Ischia island. A clear seismic signal was also recorded by the seismic monitoring network of the Neapolitan volcanic areas (Ischia, Campi Flegrei and Mt. Vesuvius) and on a regional station (Mt. Massico). On the base of the seismic recordings and on acoustic phenomena reports, we relate this event to the airblast of a bolide at about 15 Km SW of Ischia at an elevation of about 11.5 Km. The location has been obtained through probabilistic non-linear traveltime inversion in a realistic atmospheric model including wind eff ect. We will show, using statistical estimators, how the traveltime pattern is due to both atmospheric winds and bolide trajectory. Using the same reasoning we discard a human origin (supersonic jet or sea-air missile). In addition, we propose also a new algorithm for a fast acoustic traveltime computation for a moving source
Full characterization of Gaussian bipartite entangled states by a single homodyne detector
We present the full experimental reconstruction of Gaussian entangled states
generated by a type--II optical parametric oscillator (OPO) below threshold.
Our scheme provides the entire covariance matrix using a single homodyne
detector and allows for the complete characterization of bipartite Gaussian
states, including the evaluation of purity, entanglement and nonclassical
photon correlations, without a priori assumptions on the state under
investigation. Our results show that single homodyne schemes are convenient and
robust setups for the full characterization of OPO signals and represent a tool
for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR
Enhanced Nuclear Engineering Simulators
Engineering simulation is a sophisticated multi-purpose technology allowing the users of simulators to run a variety of engineering activities due to the possibility of modifying the simulated plant architecture and components, to adjust parameters, to test alternative solutions. Engineering Simulators (ES) have been built and used worldwide for a variety of purposes:
- Development and refinement of the plant design or plant modifications
- Safety analyses focused on the overall system behaviour
- Verification and Validation (V&V) of systems and components
- Development of Operational and Emergency Procedures
- Pre-Training of operators and supervisors
- High level education and Communication activities
- Human Factor Engineering Analysis
- Adaptive Control System training Engineering Simulators also play a role in developing and maintaining key nuclear skills, as knowledge repositories and tools for training at various levels of expertise
The InfraCyrus infrasound sensor
Infrasound sensors are used for a wide range of geophysical applications as the monitoring of volcanic
eruptions, the detection of bolides and the recording of infrasounds generated by earthquakes. In 2006 we
started the development of cheap infrasound sensors, based on commercial electret microphones. They have
been characterized by comparing their response function with existing broadband infrasound sensors. These
sensors, called InfraCyrus, have a good response between 1 and 10 Hz, making their application useful for
various geophysical purposes. Currently, about a dozen of sensors are deployed in the Neapolitan area
showing good performances in the recording of local and regional infrasonic transients
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