950 research outputs found
The end-to-end testbed of the Optical Metrology System on-board LISA Pathfinder
LISA Pathfinder is a technology demonstration mission for the Laser
Interferometer Space Antenna (LISA). The main experiment on-board LISA
Pathfinder is the so-called LISA Technology Package (LTP) which has the aim to
measure the differential acceleration between two free-falling test masses with
an accuracy of 3x10^(-14) ms^(-2)/sqrt[Hz] between 1 mHz and 30 mHz. This
measurement is performed interferometrically by the Optical Metrology System
(OMS) on-board LISA Pathfinder. In this paper we present the development of an
experimental end-to-end testbed of the entire OMS. It includes the
interferometer and its sub-units, the interferometer back-end which is a
phasemeter and the processing of the phasemeter output data. Furthermore,
3-axes piezo actuated mirrors are used instead of the free-falling test masses
for the characterisation of the dynamic behaviour of the system and some parts
of the Drag-free and Attitude Control System (DFACS) which controls the test
masses and the satellite. The end-to-end testbed includes all parts of the LTP
that can reasonably be tested on earth without free-falling test masses. At its
present status it consists mainly of breadboard components. Some of those have
already been replaced by Engineering Models of the LTP experiment. In the next
steps, further Engineering Models and Flight Models will also be inserted in
this testbed and tested against well characterised breadboard components. The
presented testbed is an important reference for the unit tests and can also be
used for validation of the on-board experiment during the mission
3D SPH Simulations of Shocks in Accretion Flows around black holes
We present the simulation of 3D time dependent flow of rotating ideal gas
falling into a Schwarzschild black hole. It is shown that also in the 3D case
steady shocks are formed in a wide range of parameters (initial angular
momentum and thermal energy). We therefore highlight the stability of the
phenomenon of shock formation in sub keplerian flows onto black holes, and
reenforce the role of the shocks in the high luminosity emission from black
hole candidates. The simulations have been performed using a parallelized code
based on the Smoothed Particles Hydrodynamics method (SPH). We also discuss
some properties of the shock problem that allow its use as a quantitative test
of the accuracy of the used numerical method. This shows that the accuracy of
SPH is acceptable although not excellent.Comment: 9 pages, 22 figure
Effect of ELF e.m. fields on metalloprotein redox-active sites
The peculiarity of the distribution and geometry of metallic ions in enzymes
pushed us to set the hypothesis that metallic ions in active-site act like tiny
antennas able to pick up very feeble e.m. signals. Enzymatic activity of Cu2+,
Zn2+ Superoxide Dismutase (SOD1) and Fe2+ Xanthine Oxidase (XO) has been
studied, following in vitro generation and removal of free radicals. We
observed that Superoxide radicals generation by XO is increased by a weak field
having the Larmor frequency fL of Fe2+ while the SOD1 kinetics is sensibly
reduced by exposure to a weak field having the frequency fL of Cu2+ ion.Comment: 18 pages, 4 figure
The Crab pulsar light curve in the soft gamma ray range: FIGARO II results
The FIGARO II experiment (a large area, balloon borne, crystal scintillator detector working from 0.15 to 4.3 MeV) observed the Crab pulsar on 1990 Jul. 9 for about seven hours. The study of the pulse profile confirms some structures detected with a low significance during the shorter observation of 1986, and adds new important elements to the picture. In particular, between the two main peaks, two secondary peaks appear centered at phase values 0.1 and 0.3, in the energy range 0.38 to 0.49 MeV; in the same energy range, a spectral feature at 0.44 MeV, interpreted as a redshifted positron annihilation line, was observed during the same balloon flight in the phase interval including the second main peak and the neighboring secondary peak. If the phase interval considered is extended to include also the other secondary peak, the significance of the spectral line appears to increase
Evaluation of the efficacy of animal-assisted therapy based on the reality orientation therapy protocol in Alzheimer's disease patients: a pilot study.
BACKGROUND: The aim of this study was to evaluate the efficacy of animal-assisted therapy (AAT) in elderly patients affected by Alzheimer's disease based on the formal reality orientation therapy (ROT) protocol.
METHODS: Our study was carried out at an Alzheimer's centre for 6 months. A homogeneous sample (age, Mini-Mental State Examination (MMSE), 15-item Geriatric Depression Scale (GDS)) of 50 patients was selected at random and successively. Patients were divided into three groups: (i) 20 patients received a course of AAT (AAT group) based on the ROT protocol; (ii) 20 patients were engaged exclusively in activities based on the ROT group; and (iii) 10 patients (control group) participated in no stimulations. MMSE and GDS were administered at time 0 (T0 ) and time 1 (T1 ) to all three groups. Differences within groups between T0 and T1 for GDS and MMSE scores were analyzed by Student's t-test. Differences between group means were analyzed using an anova test with the Bonferroni-Dunn test for post-hoc comparisons.
RESULTS: Both the AAT group and ROT group had improved GDS scores and showed a slight improvement in terms of mood. On the GDS, the AAT group improved from 11.5 (T0 ) to 9.5 (T1 ), and the ROT group improved from 11.6 (T0 ) to 10.5 (T1 ). At the same time, a slight improvement in cognitive function, as measured by the MMSE, was observed. In the AAT group, mean MMSE was 20.2 at T0 and 21.5 at T1 , and in the ROT group, it was 19.9 at T0 and 20.0 at T1 . In the control group, the average values of both the GDS and MMSE remained unchanged. The Bonferroni-Dunn results showed statistically significant differences between groups, particularly between the AAT group and the other two (P < 0.001).
CONCLUSIONS: Pet therapy interventions based on the formal ROT protocol were effective and, compared to the ROT, provided encouraging and statistically significant results
Modeling provincial Covid-19 epidemic data in Italy using an adjusted time-dependent SIRD model
In this paper we develop a predictive model for the spread of COVID-19 infection at a provincial (i.e. EU NUTS-3) level in Italy by using official data from the Italian Ministry of Health integrated with data extracted from daily official press conferences of regional authorities and from local newspaper websites. This integration is mainly concerned with COVID-19 cause specific death data which are not available at NUTS-3 level from open official data data channels. An adjusted time-dependent SIRD model is used to predict the behavior of the epidemic, specifically the number of susceptible, infected, deceased and recovered people. Predictive model performance is evaluated using comparison with real data
Energy resolution and throughput of a new real time digital pulse processing system for x-ray and gamma ray semiconductor detectors
New generation spectroscopy systems have advanced towards digital pulse processing
(DPP) approaches. DPP systems, based on direct digitizing and processing of detector signals,
have recently been favoured over analog pulse processing electronics, ensuring higher flexibility,
stability, lower dead time, higher throughput and better spectroscopic performance. In this work,
we present the performance of a new real time DPP system for X-ray and gamma ray semiconductor
detectors. The system is based on a commercial digitizer equipped with a custom DPP firmware,
developed by our group, for on-line pulse shape and height analysis. X-ray and gamma ray spectra
measurements with cadmium telluride (CdTe) and germanium (Ge) detectors, coupled to resistivefeedback
preamplifiers, highlight the excellent performance of the system both at low and high rate
environments (up to 800 kcps). A comparison with a conventional analog electronics showed the
better high-rate capabilities of the digital approach, in terms of energy resolution and throughput.
These results make the proposed DPP system a very attractive tool for both laboratory research and
for the development of advanced detection systems for high-rate-resolution spectroscopic imaging,
recently proposed in diagnostic medicine, industrial imaging and security screening
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