305 research outputs found
Holomorphic symmetric differentials and a birational characterization of Abelian Varieties
A generically generated vector bundle on a smooth projective variety yields a
rational map to a Grassmannian, called Kodaira map. We answer a previous
question, raised by the asymptotic behaviour of such maps, giving rise to a
birational characterization of abelian varieties.
In particular we prove that, under the conjectures of the Minimal Model
Program, a smooth projective variety is birational to an abelian variety if and
only if it has Kodaira dimension 0 and some symmetric power of its cotangent
sheaf is generically generated by its global sections.Comment: UPDATED: more details added on main proo
Standard isotrivial fibrations with pg = q = 1, II
A smooth, projective surface S is called a standard isotrivial fibration if there exists a finite group G which acts faithfully on two smooth projective curves C and F so that S is isomorphic to the minimal desingularization of T {colon equals} (C × F) / G. Standard isotrivial fibrations of general type with pg = q = 1 have been classified in [F. Polizzi, Standard isotrivial fibrations with pg = q = 1, J. Algebra 321 (2009),1600-1631] under the assumption that T has only Rational Double Points as singularities. In the present paper we extend this result, classifying all cases where S is a minimal model. As a by-product, we provide the first examples of minimal surfaces of general type with pg = q = 1, KS2 = 5 and Albanese fibration of genus 3. Finally, we show with explicit examples that the case where S is not minimal actually occurs. © 2009 Elsevier B.V. All rights reserved
Coping with cancer: A prospective psycho-social analysis of cancer patients and their non-medical caregivers (cg) – A goim study
n/
Comparison of ERBS orbit determination accuracy using batch least-squares and sequential methods
The Flight Dynamics Div. (FDD) at NASA-Goddard commissioned a study to develop the Real Time Orbit Determination/Enhanced (RTOD/E) system as a prototype system for sequential orbit determination of spacecraft on a DOS based personal computer (PC). An overview is presented of RTOD/E capabilities and the results are presented of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite System (TDRSS) user spacecraft obtained using RTOS/E on a PC with the accuracy of an established batch least squares system, the Goddard Trajectory Determination System (GTDS), operating on a mainframe computer. RTOD/E was used to perform sequential orbit determination for the Earth Radiation Budget Satellite (ERBS), and the Goddard Trajectory Determination System (GTDS) was used to perform the batch least squares orbit determination. The estimated ERBS ephemerides were obtained for the Aug. 16 to 22, 1989, timeframe, during which intensive TDRSS tracking data for ERBS were available. Independent assessments were made to examine the consistencies of results obtained by the batch and sequential methods. Comparisons were made between the forward filtered RTOD/E orbit solutions and definitive GTDS orbit solutions for ERBS; the solution differences were less than 40 meters after the filter had reached steady state
The fundamental group and torsion group of Beauville surfaces
We give a survey on the fundamental group of surfaces isogenous to a higher
product. If the surfaces are regular, e.g. if they are Beauville surfaces, the
first homology group is a finite group. We present a MAGMA script which
calculates the first homology groups of regular surfaces isogenous to a
product.Comment: 14 pages; MAGMA script included; v2: minor corrections, final version
to appear in the Proceedings of the Conference "Beauville Surfaces and
Groups", Newcastle University (UK), 7-9th June 201
Limited versus extended pelvic lymphadenectomy during robot-assisted radical prostatectomy: impact on the number of nodes and on nodal invasion
Improved solution accuracy for Landsat-4 (TDRSS-user) orbit determination
This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite System (TDRSS) user spacecraft, Landsat-4, obtained using a Prototype Filter Smoother (PFS), with the accuracy of an established batch-least-squares system, the Goddard Trajectory Determination System (GTDS). The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the January 17-23, 1991, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. Independent assessments were made of the consistencies (overlap comparisons for the batch case and convariances for the sequential case) of solutions produced by the batch and sequential methods. The filtered and smoothed PFS orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were generally less than 15 meters
PHIL photoinjector test line
LAL is now equiped with its own platform for photoinjectors tests and
Research and Developement, named PHIL (PHotoInjectors at LAL). This facility
has two main purposes: push the limits of the photoinjectors performances
working on both the design and the associated technology and provide a low
energy (MeV) short pulses (ps) electron beam for the interested users. Another
very important goal of this machine will be to provide an opportunity to form
accelerator physics students, working in a high technology environment. To
achieve this goal a test line was realised equipped with an RF source, magnets
and beam diagnostics. In this article we will desrcibe the PHIL beamline and
its characteristics together with the description of the first two
photoinjector realised in LAL and tested: the ALPHAX and the PHIN RF Guns
Safety and feasibility of thullium laser transurethral resection of prostate for the treatment of benign prostatic enlargement in overweight patients
Objective: We aimed to determine safety and feasibility of thulium laser transurethral vapoenucleation of prostate (ThuVEP) for treatment of obese patients affected by benign prostatic hyperplasia (BPH). Methods: We retrospectively analysed data of 452 patients with BPH who underwent ThuVEP from February 2012 to March 2016 in a single center. Patients were divided into three groups according to body mass index (BMI, kg/m2): Normal weight (18.5 64 BMI < 25; Group A), overweight (25 64 BMI < 30; Group B) and obese (BMI 65 30; Group C), for a total of 412 patients evaluable for this study. Preoperative total serum prostate-specific antigen (PSA), digital rectal examination of the prostate, transrectal ultrasound (TRUS), renal ultrasound, urine culture, uroflowmetry, International Prostate Symptoms Score (IPSS), and Quality of Life (QoL) score were analyzed. Post-operative complications, hospital stay and days of catheterization, questionnaires and uroflowmetry at 1 and 3 months after surgery were evaluated. Preoperative data, surgical outcomes, complication rate and clinical outcomes were compared between groups. Results: The median age of patients was 69 years (Interquartile Range [IQR 10]). The preoperative median IPSS among groups was 19 (IQR 8.75), 20 (IQR 10), and 18 (IQR 10) respectively. At 1 and 3 months of follow-up, this value was 8 (IQR 7), 8 (IQR 4), 7 (IQR 5) and 5 (IQR 6.25), 5 (IQR 6), 6 (IQR 5), respectively (all p between groups > 0.05). There was no statistically significant difference among three groups as for hospital stay and days of catheterization (p > 0.05). Conclusion: Our results showed that ThuVEP was safe and feasible even in overweight patients with substantially enlarged prostate
Improved solution accuracy for TDRSS-based TOPEX/Poseidon orbit determination
Orbit determination results are obtained by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) using a batch-least-squares estimator available in the Goddard Trajectory Determination System (GTDS) and an extended Kalman filter estimation system to process Tracking and Data Relay Satellite (TDRS) System (TDRSS) measurements. GTDS is the operational orbit determination system used by the FDD in support of the Ocean Topography Experiment (TOPEX)/Poseidon spacecraft navigation and health and safety operations. The extended Kalman filter was implemented in an orbit determination analysis prototype system, closely related to the Real-Time Orbit Determination System/Enhanced (RTOD/E) system. In addition, the Precision Orbit Determination (POD) team within the GSFC Space Geodesy Branch generated an independent set of high-accuracy trajectories to support the TOPEX/Poseidon scientific data. These latter solutions use the geodynamics (GEODYN) orbit determination system with laser ranging and Doppler Orbitography and Radiopositioning integrated by satellite (DORIS) tracking measurements. The TOPEX/Poseidon trajectories were estimated for November 7 through November 11, 1992, the timeframe under study. Independent assessments were made of the consistencies of solutions produced by the batch and sequential methods. The batch-least-squares solutions were assessed based on the solution residuals, while the sequential solutions were assessed based on primarily the estimated covariances. The batch-least-squares and sequential orbit solutions were compared with the definitive POD orbit solutions. The solution differences were generally less than 2 meters for the batch-least-squares and less than 13 meters for the sequential estimation solutions. After the sequential estimation solutions were processed with a smoother algorithm, position differences with POD orbit solutions of less than 7 meters were obtained. The differences among the POD, GTDS, and filter/smoother solutions can be traced to differences in modeling and tracking data types, which are being analyzed in detail
- …