Search

SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the International Space Station during Early Utilization Phase aimed at measuring the microwave polarized emission with FWHM = 7deg, in the frequency range 22-90 GHz. The Galactic polarized emission can be observed at the lower frequencies and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where contaminants are expected to be less important. The extremely low level of the CMB Polarization signal (< 1 uK) calls for intrinsically stable radiometers. The SPOrt instrument is expressly devoted to CMB polarization measurements and the whole design has been optimized for minimizing instrumental polarization effects. In this contribution we present the receiver architecture based on correlation techniques, the analysis showing its intrinsic stability and the custom hardware development carried out to detect such a low signal., 9 pages, 5 figures, conference proceeding, to appear in "Polarimetry in Astronomy", SPIE Symposium on 'Astronomical Telescopes and Instrumentation', Waikoloa, August 22-28 2002

We describe a simple but effective iterative procedure specifically designed to destripe Q and U Stokes parameter data as those collected by the SPOrt experiment onboard the International Space Station (ISS). The method is general enough to be useful for other experiments, both in polarization and total intensity. The only requirement for the algorithm to work properly is that the receiver knee frequency must be lower than the signal modulation frequency, corresponding in our case to the ISS orbit period. Detailed performances of the technique are presented in the context of the SPOrt experiment, both in terms of added rms noise and residual correlated noise., Comment: Accepted for publication by A&A (8 pages, 6 figures)

A structured methodology for hybrid robot controllers design is presented. The key elements of the proposed technique are: the object-oriented approach, compliance with international standards, hybrid models and automatic code generation. In particular, a life cycle model for the control system development is considered, functional and implementation reference models are introduced, and a computer aided control system design environment is described. Such tools support the robot controller design, by means of structured modelling, simulation and run-time control generation. Furthermore, the development and implementation of robot mission for an industrial manipulator is illustrated as an application example of the proposed methodology, showing how the different design phases are dealt with.

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry $A_1$. Longitudinally polarised positrons were scattered off a longitudinally polarised hydrogen target for values of $Q^2$ between 1.2 and 12 GeV$^2$ and values of $W^2$ between 1 and 4 GeV$^2$. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable $x$. This finding implies that the description of $A_1$ in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of $Q^2$ above 1.6 GeV$^2$., 5 pages, 1 eps figure, table added, new references added, in print in Phys. Rev. Lett

We study the angular power spectra of polarized Galactic synchrotron in the range 10~0.05., Comment: 20 pages, 9 figures, accepted to New Astronomy

We study the angular power spectra of the polarized component of the Galactic synchrotron emission in the 28-deg^2 Test Region of the Southern Galactic Plane Survey at 1.4 GHz. These data were obtained by the Australia Telescope Compact Array and allow us to investigate angular power spectra down to arcminute scales. We find that, at this frequency, the polarization spectra for E- and B-modes seem to be affected by Faraday rotation produced in compact foreground screens. A different behavior is shown by the angular spectrum of the polarized intensity PI=\sqrt{Q^2+U^2}. This is well fitted by a power law with slope \~1.7, which agrees with higher frequency results and can probably be more confidently extrapolated to the cosmological window., 11 pages, 6 figures, accepted for publication in ApJ

We study the angular power spectra of the polarized Galactic synchrotron emission in the range 10≲l⩽800, at several frequencies between 0.4 and 2.7 GHz and at several Galactic latitudes up to near the North Galactic Pole. We properly distinguish between the various polarization spectra that can be defined and measured, including the CPIl spectrum which is insensitive to the polarization direction.

A new destriping technique suitable for polarization data is described. The performances of the algorithm are studied in the frame of the SPOrt Experiment onboard the International Space Station.

BaR-SPOrt (Balloon-borne Radiometer for Sky Polarization Observations) is an experiment to measure the linearly polarized emission of sky patches aboard a long duration stratospheric balloon. It consists of high sensitivity correlation polarimeters operating in the millimeter wavelength region and coupled to a telescope to obtain a sub-degree angular resolution for direct measurements of the Q and U Stokes parameters. This project shares most of the know-how and sophisticated technology developed for the SPOrt experiment aboard the International Space Station. The instrument design, the various solutions to reduce the systematics and the observing strategy are here described.

BaR-SPOrt is a project to measure the linearly polarised emission of 20degtimes20deg sky patches from a stratospheric balloon, at 32 GHz and 90 GHz. It consists of correlation polarimeters for direct measurements of the Q and U Stokes parameters, coupled to optics providing a beam of 0.5deg (32 GHz) and 0.2deg (90 GHz). The instrument design is described. Particular emphasis is put on the hardware solutions adopted to reduce the systematic effects in high sensitivity polarisation measurements

A single-spin asymmetry in the distribution of exclusively produced pi^+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin \phi moment of the polarization asymmetry of the cross section is measured to be -0.18 +/- 0.05 (stat.) +/- 0.02 (syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing x and increasing -t and vanish at t -> t_min (where x is the Bjorken scaling variable and t is the squared four-momentum transferred to the nucleon)., Comment: PLB accepted version, 6 pages, 4 figures, LaTex (revtex4), corrected typo

The beam-spin asymmetry in hard electroproduction of photons has been measured for the first time. The data have been accumulated by the HERMES experiment at DESY using the HERA 27.6 GeV longitudinally polarized positron beam and an unpolarized hydrogen gas target. The asymmetry in the azimuthal distribution of the produced photons in the angle phi relative to the lepton scattering plane was determined with respect to the helicity state of the incoming positron beam. The beam-spin analyzing power in the sin(phi) moment was measured to be -0.23 +/- 0.04(stat) +/- 0.03(syst) in the missing-mass range below 1.7 GeV. The observed asymmetry is attributed to the interference of the Bethe-Heitler and deeply-virtual Compton scattering processes., Comment: 6 pages, 5 figures, revised experimental description

Galactic synchrotron will be an important contaminant for forthcoming experiments on CMB polarization. We investigate the angular power spectra of polarized Galactic synchrotron in several surveys (Parkes at 2.4 GHz, Effelsberg at 2.7 GHz and 1.4 GHz), showing that partial sky coverage analysis may lead to largely different results. Reasonable extrapolations to tens of GHz allow us to find a region in the (v,l) plane where the CMB polarized signal is expected to prevail largely.

We derive the angular power spectra of intensity and polarization of Galactic synchrotron emission in the range 36 < l < 10^3 from the Parkes survey mapping the southern Galactic plane at 2.4 GHz. The polarization spectra of both electric and magnetic parity up to l \simeq 10^3 are approximated very well by power laws with slope coefficients \simeq 1.4, quite different from the CMB spectra. We show that no problem should arise from Galactic synchrotron for measurements of CMB polarization in the cosmological window., 15 pages with 6 eps figures. Accepted for publication in New Astronomy

We present the cosmological and astrophysical objectives of the SPOrt mission, which is scheduled for flying on the International Space Station (ISS) in the year 2002 with the purpose of measuring the diffuse sky polarized radiation in the microwave region. We discuss the problem of disentangling the cosmic background polarized signal from the Galactic foregrounds., 10 pages; 5 PS figures; requires aipproc2.cls, aipproc2.sty, epsfc.tex; to appear in Proc. of ``3K Cosmology'', Rome 5-10 Oct. 1998

In the framework of the International Space Station (ISSA) utilization a project to measure the sky diffuse polarized emission at microwave frequencies has been presented to the ESA AO. After its selection by ESA the Sky Polarization Observatory (SPOrt) has been slightly modified, within ISSA constrains, to meet better its scientific goal. In this paper the current design of SPOrt is presented with emphasis on changes which have a major impact on the overall performances and that were imposed by the ISSA environment.

The Sky Polarization Observatory (SPOrt) is presented as a project aimed to measure the diffuse sky polarized emission, from the International Space Station, in the frequency range 20-90 GHz with 7 degrees of HPBW. The SPOrt experimental configuration is described with emphasis on the aspects that make SPOrt the first European scientific payload operating at microwave wavelengths., 8 pages; 5 PS figures; requires aipproc2.cls, aipproc2.sty, epsfc.sty; to appear in Proc. of ``3K Cosmology'', Rome 5-10 Oct. 1998

We applay the genus statistics to simulated CMB polarization maps, constructed from the secondary-ionization cosmological models in experimental situations comparable to those of forthcoming space experiments. We find that both the cosmic baryon density and the spectral index of density perturbations are strongly anicorrelated to the reionization redshift. Using the Fisher matrix approach we show that the accuracy on the spectral index and optical depth to the last scattering are improved in the case of genus statistics when comparing with the accuracy obtained from the standard power spectrum statistics., 22 pages in LaTex format, 4 figures in a single ps file Accepted at New Astronomy

We report the effects of treatment with plasma-exchange (PE) and intravenous immune globulins (IVIg) in 36 out of 50 patients with Guillain-Barré syndrome (GBS) recruited by an incidence study in the Emilia-Romagna region of Italy. Comparison of the patients treated with PE and IVIg showed no significant differences in terms of effectiveness in improving the clinical course of GBS: at one month, respectively 11.1% and 25% had recovered, and 55.5% and 58.3% had improved by at least one grade. These results are in agreement with those of the Dutch GBS trial. No relapses were observed in either group. Moreover, our results showed no difference in clinical outcome at 1 and 3 months between the patients receiving only one therapy and those receiving two; a second cycle of therapy did not seem to improve the clinical course of the disease significantly. We conclude that PE and IVIg are both safe and effective therapies for GBS.

This study describes the technique and results of a new approach for the hysteroscopic catheterization of the Fallopian tube in order to transfer gametes (hysteroscopic GIFT). Ovarian stimulation was started on 51 patients. Three cycles were cancelled because of a failure of ovarian response. Forty-eight patients underwent hysteroscopic GIFT utilizing a technique completely different, easier, faster and more precise than that previously reported. Fourteen pregnancies were achieved (29.2%) of which five are ongoing, six patients have delivered and three have aborted. No ectopic pregnancies were observed.

The presence of sexual steroid receptor proteins in thyroid tissue has been previously demonstrated by biochemical means. The aim of this study was to determine the estrogen (ER) and progesterone (PR) receptors in malignant (12 papillary and 1 follicular carcinoma) and nonmalignant (19 multinodular goiters, 1 Graves’ disease, 1 Hashimoto’s thyroiditis) thyroid diseases using immunocy-tochemical assay employing monoclonal anti-ER and anti-PR antibodies and the peroxidase-antiperoxi-dase technique. Positive results were obtained in 24/34 (70%) for ER (ER-ICA+) and 22/34 (64%) for PR (PR-ICA+). To evaluate the possible interference of thyroperoxidase in the immunostaining, in consecutive sections of a positive specimen, primary antibody or primary antibody plus bridging antibody or PAP complex was omitted. Using these modified procedures, staining distribution was similar to that obtained by the standard procedure: in contrast, no staining was found in the positive control, i.e. a breast cancer specimen. The inhibition of the endogenous peroxidase caused a loss of staining in both the standard and modified procedures on thyroid specimens; no staining modification was obtained in the positive control. These results suggest that the staining observed in thyroid tissue is not specific and related to the activity of thyroperoxidase on chromogen solution. The complete loss of staining after peroxidase inhibition appears to be in contrast with the results obtained by biochemical method, and different antigenicity of thyroid receptors in comparison with breast receptors may explain this discrepancy.

Nitrogen implantation in Si single crystals in the 600-–1400 keV energy range in random, 〈100〉 and 〈110〉 alignment conditions was performed. The 6×10 13 -2×10 16 fluence range was investigated. Double crystal diffraction (DCD) and RBS-channeling analysis were performed in order to extract the damage profiles and the damage production rate as a function of the implanted ion fluence. A strong dependence of the damage on the implantation geometry has been observed and discussed.

The ability to detect tunneling activity under borders and perimeters has become an increasingly important problem. Persistent, automated, passive surveillance of expansive areas for tunnel activity is a technical challenge because of the processing and hardware costs. Further, data bandwidth concerns prohibit transmission of large amounts of time‐series data to a central processing location but there remains a desire for human review of suspect signals and archiving to develop trends in time. To meet these technical challenges, sensor array and signal processing approaches which exploit geophysical phenomena to distinguish tunnel activity from surface noise were developed to rapidly and reliably detect potential subsurface threat signals with a minimized set of sensors, very low data bandwidth requirements, and a reduced set of centralized processing hardware. Time series review and archiving can then be performed for limited sets of the most suspect data. Analysis and results from recent controlled tunn...

The correlation of the most important prognostic indicators was evaluated in 75 breast cancer cases. Estrogen-progesterone receptors and proliferating activity were analyzed by immunocytochemical methods (ER-ICA, PR-ICA, Ki-67). Both steroid receptors were inversely correlated with the proliferating activity (ER-ICA vs Ki-67, p < 0.003; PR-ICA vs. Ki-67, p < 0.0001). No correlation was found between steroid receptors or cell kinetics and tumor size or lymph node status. These findings confirm the relevance of biochemical and kinetic parameters as independent markers in breast cancer and suggest a routine use of the simple immunocytochemical methods in assessing the biological behavior of tumors.

The influence of Rapid Thermal Annealing (RTA), on silicon electrical and structural characteristics is studied. A degradation directly connected to the technique is observed in electron beam annealed samples, while the lamp annealed ones do not change crystal properties for low temperature anneals.

A rare case of complete colo-colic invagination of the portion of the proximal transverse colon at the splenic flexure determined by voluminous submucous lipoma is reported. After a short review of the literature, some anatomoclinical remarks and a comment on surgical indications are presented.

Silicon doping by high fluence pulsed laser irradiation in BC13 and PC13 atmospheres has been performed giving rise to shallow heavily doped junctions. The doped layers are free from extended defects, nevertheless a reduction of carrier mobility has been evidenced. Point defects originated by the fast solidification of the molten surface are responsible for the degradation of the transpOrt properties in the doped layer. The strain profile, originated from the point defect distribution, have been measured for different irradiation conditions. It was evidenced that the defective region is mostly limited inside the doped layer. A remarkable reduction of point defects is obseved when the laser irradiation takes place on samples kept at 400°C. At this temperature the speed of the solidification front is reduced of about 40%, thus limiting the number of quenched point defects.

By simulation of X-ray rocking curves of Si-Ge alloys grown on Si by molecular beam epitaxy and of Ge implanted samples, the Ge composition, the linear lattice expansion coefficient, the strain depth-distribution and the static Debye-Waller factor in the MBE alloys have been determined.

The anisotropies in the 60-micron IRAS Point Source Catalog are investigated at all angular scales gamma greater than 2 deg. Several different types of harmonic analysis are performed up to the octopole terms. While the dipole amplitude is not much affected by the inclusion of higher-order harmonics, the maximum direction is shifted by about 30 deg in Galactic latitude when the octopole terms are included in a simultaneous fitting. The amplitudes of individual harmonics with l greater than 2 are strongly correlated, but the overall quadrupole and octopole moments are determined very well. The quadrupole-to-dipole ratio is 1.5-1.8 and steadily increases with flux in the range 0.6-20 Jy, while the octopole-to-dipole ratio is around 0.5-0.6 with no systematic flux dependence. The results are compared with a simple model where the cosmic structure is modeled by an isotropic field of stochastic perturbations. 18 refs.

The new gas filled separator for fission products JOSEF has a considerably higher resolution than any older isotope separator of this type. A mass resolution of A / ΔA = 79 and a nuclear charge resolution of Z / ΔZ = 38 have been measured for the light fission product group. Unambiguous identification of unknown nuclei with masses up to A = 150 is possible. The resolution is high enough to determine fission yields and to reveal isomeric states in fission products by making use of the separation according to the mass and nuclear charge. The results suggest an extended application of gas filled separators for the investigation of the heavy products also of nuclear reactions other than fission.

Though the implantation of hydrogen into (100) silicon at 15.5 keV and 75 keV is substantially linear with fluence in the range 1014−2×1016 cm−2 small nonlinear phenomena are observed considering the chemical and damage profiles, as determined by secondary ion mass spectrometry and double crystal X-ray diffraction, respectively. A general theory to describe quantitatively nonlinear effects in hydrogen implantation into silicon is developed and compared with experimental data; the parameters of this theory can be evaluated with ab initio MARLOWE calculations.

The linear polarization degree of the cosmological background has been investigated at angular scales ranging between 0.5/sup 0/ and 40/sup 0/ by means of a balloon-borne far-infrared polarimeter. An upper limit has been found of 8 x 10/sup -/4 at 40/sup 0/ (at one standard deviation). Some cosmological implications are discussed.

We show that off-equatorial circular orbits of charged particles may exist in the Kerr-Newman space-time. Their relevance to the definitions of a fluid source for the metric is pointed out.

Transient enhanced diffusion of phosphorus in silicon has been investigated for implants below and above the threshold for a complete amorphization. Rapid thermal processes (electron beam) and conventional furnaces have been used for the annealing. In the case of implants below amorphization, a strong enhanced diffusion, proportional to the amount of damage produced, has been observed. The extent of the phenomenon is practically independent of the damage depth position. In contrast to this, the formation of extended defects at the original amorphous-crystalline interface makes the diffusivity strongly dependent on depth in the case of post-amorphized samples. No enhanced diffusion effect is observed if the dopant is confined in the amorphous layer, while a remarkable increase in the diffusivity is detected for the dopant located in the crystalline region beyond the amorphous-crystalline interface. Damage distribution after implantation and its evolution during annealing have been determined by double crystal x-ray diffraction and correlated to anomalous P diffusivity. A qualitative distribution of the interstitial excess in solution in the silicon lattice during annealing is proposed for the two different cases. These point defects, released by the dissolution of the interstitial clusters produced by the implanted ions, have been identified as responsible for the observed enhanced P diffusion.

Transient enhanced diffusion of phosphorus in silicon has been investigated for implants below and above the threshold for complete amorphization. In the first case, a strong enhanced diffusion, proportional to the amount of damage produced, has been observed. The extent of the phenomenon is practically independent of the damage depth position. On the contrary, the formation of extended defects at the original amorphous-crystalline interface makes the diffusivity strongly dependent on depth in the case of postamorphized samples. No enhanced diffusion effect is observed if the dopant is confined in the amorphous layer, while a remarkable increase in the diffusivity is detected for the dopant located in the crystalline region beyond the amorphous-crystalline interface.

We analyse the evolution of Bianchi type-VIIh cosmological models during the lepton era and the subsequent adiabatic epochs. We find that these model cannot generally attain to the low-density regime with a reasonable anisotropy level because of a curvature—anisotropy coupling. The primordial damping due to neutrino viscosity, although very effective for the entropy production, cannot help to match to isotropy requirement at the present epoch.

We analyse in detail the spectral shape of the Sunyaev-Zel'dovich effect in the cosmic background radiation, taking into account the relativistic corrections for a hot electron gas. We calculate the displacement of the zero-signal frequency, which is especially informative in a new method for measuring the millimetric temperature of the background radiation; we also present a simple analytical expression, to be used to fit the experimental data in spectral measurements of the effect in very hot cluster gases.