Search Results - (Author, Cooperation:G. Ghiringhelli)

2018-06-20

American Physical Society (APS)

1098-0121

1095-3795

Physics

Electronic structure and strongly correlated systems

2018-10-11

American Physical Society (APS)

1098-0121

1095-3795

Physics

Superfluidity and superconductivity

2018-09-25

American Physical Society (APS)

1098-0121

1095-3795

Physics

Electronic structure and strongly correlated systems

2012-07-17

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

We present the design and performance of a magnetic circuit suitable for magnetizing solid samples in the measurements of soft x-ray emission dichroism excited by synchrotron radiation. The system allows a variety of samples to be magnetized and satisfies the rather stringent geometrical constraints due to the need for minimizing the effect of photon self-absorption by the sample. The magnetic circuit is ultrahigh vacuum compatible, can reach about 2800 G, and allows fine adjustment of sample position. © 1996 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

We have mounted a compact 25 kV mini-Mott spin polarimeter on a commercial high-throughput hemispherical electron analyzer with a double purpose: to maximize the polarization detection and to preserve the original efficiency of the spectrometer in the spin-integrated measurements. We have thus replaced the 16-anode microchannel-plate detector with a 12-anode microsphere-plate detector in parallel with a Rice University retarding Mott spin polarimeter. Passing from one detection mode to the other is quick and easy. The transfer optics from the analyzer exit slit to the scattering target of the polarimeter allows the full potential of both the electron analyzer and the spin detector to be exploited. The expected effective Sherman function (Seff=0.17) and figure of merit (η0≅1.4×10−4) are found in the spin-resolved mode, and only 25% of the original efficiency is lost in the spin-integrated acquisitions. © 1999 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

PoLIFEMo (Polarized Light Improved Flux Efficiency Monochromator) is the name of a spherical grating monochromator designed with the purpose of maximizing the photon intensity on a sample. The device is mainly conceived to improve performances of an x-ray emission spectrometer, whose limiting factor is often the counting rate. By keeping the exit slit fixed, it is possible to get a small spot size (∼35 μm vertically) on a sample placed just near the exit slit, without the need of postgrating refocusing optics. No entrance slit is used because of the low beam divergence, allowing the use of a virtual source in a converging beam geometry. The tuning of the output energy is done by translating and pitching the spherical grating. The resolving power is higher than 1000 over the whole energy range (500–1500 eV). A detailed analysis of the optical performances is given, mostly in comparison with the Dragon-type monochromator. The actual realization of the device is described, together with the specific motivations and the experimental performances. PoLIFEMo has been installed on beam line ID12B at the European Synchrotron Radiation Facility since July 1996. © 1998 American Institute of Physics.

Electronic Resource

1432-0827

Key words: Bone mineral density — Bone size — Osteoporosis — Vertebral fractures.

Springer Online Journal Archives 1860-2000

Biology

Medicine

Physics

Abstract. The bone mineral density (BMD) at the lumbar spine, proximal femur, and total skeleton was evaluated in 38 men with primary osteoporosis and vertebral fractures. BMD of the patients was significantly reduced over all skeletal areas compared with controls. The Z-score of the lumbar spine (−2.8 ± 0.9) was less than that of the other areas (P 〈 0.001) except the legs (−2.5 ± 1.1) (p.n.s.) showing that bone loss had a tendency to be greater over the axial skeleton. Vertebral dimensions compared with age-matched controls were as follows: projected L2–L4 area (cm 2): 45.7 ± 5.6 versus 53.7 ± 3.6 (P 〈 0.001); vertebral width (cm): 4.37 ± 0.44 versus 4.90 ± 0.36 (P 〈 0.001). Serum biochemical parameters and testosterone levels were similar between osteoporotic and control men. We conclude that men with vertebral osteoporotic fractures have reduced vertebral BMD and vertebral dimensions compared with age-matched controls. Thus, these findings indicate that the achievement of a reduced bone size at the end of the growth period or a failure of periosteal increase during adult life is likely to contribute to the pathogenesis of the vertebral fractures observed in older men.

Electronic Resource

1432-1750

Springer Online Journal Archives 1860-2000

Medicine

Zusammenfassung Die Höchstwerte des Atemgrenzwertes werden bei Gesunden und auch bei Lungenkranken bei einer Atemfrequenz von 100/min erreicht. Von dann ab ist eine Zunahme nicht mehr statistisch sicher. Der Atemgrenzwert bleibt praktisch unverändert hoch. Auch bei einer Atemfrequenz von 200/min ist die geatmete Luftmenge nie kleiner als die des physiologischen Totraumes. Um die höchsten Ventilationswerte zu erreichen, muß der Proband, falls es sich um einen Lungenkranken handelt, eine höhere Atemfrequenz wählen als der Gesunde, um den Bruchteil der Vitalkapazität, der so schnell als möglich ventiliert werden kann, auszunützen. Die Höchstwerte des Atemgrenzwertes werden durch eine so schnell und so tief wie mögliche Atmung bei willkürlichem Atemrhythmus erreicht.

Electronic Resource

1432-1750

Springer Online Journal Archives 1860-2000

Medicine

Electronic Resource

1573-269X

tiltrotor ; multi-body dynamics ; finite volume beams

Springer Online Journal Archives 1860-2000

Mathematics

Abstract The paper describes the aeroelastic analysis of a tiltrotor configuration. The 1/5 scale wind tunnel semispan model of the V-22 tiltrotor aircraft is considered. The analysis is performed by means of a multi-body code, based on an original formulation. The differential equilibrium problem is stated in terms of first-order differential equations. The equilibrium equations of every rigid body are written together with the definitions of the momenta. The bodies are connected by kinematic constraints applied in the form of Lagrangian multipliers. Deformable components are mainly modelled by means of beam elements based on an original finite volume formulation. Multi-disciplinary problems can be solved by adding user-defined differential equations. In the presented analysis, the equations related to the control of the swash-plate of the model are considered. Advantages of a multi-body aeroelastic code over existing comprehensive rotorcraft codes include the exact modelling of the kinematics of the hub, the detailed modelling of the flexibility of critical hub components, and the possibility to simulate steady flight conditions as well as wind-up and maneuvers. The simulations described in the paper include (1) the analysis of the aeroelastic stability, with particular regard to the proprotor/pylon instability that is peculiar to tiltrotors, (2) the determination of the dynamic behavior of the system and of the loads due to typical maneuvers, with particular regard to the conversion from helicopter to airplane mode, and (3) the stress evaluation in critical components, such as the pitch links and the conversion downstop spring.

Electronic Resource