On the heliolatitudinal variation of the galactic cosmic-ray intensity. Comparison with Ulysses measurements

International audienceWe study the dependence of cosmic rays with heliolatitude using a simple method and compare the results with the actual data from Ulysses and IMP spacecraft. We reproduce the galactic cosmic-ray heliographic latitudinal intensity variations, applying a semi-empirical, 2-D diffusion-convection model for the cosmic-ray transport in the interplanetary space. This model is a modification of our previous 1-D model (Exarhos and Moussas, 2001) and includes not only the radial diffusion of the cosmic-ray particles but also the latitudinal diffusion. Dividing the interplanetary region into "spherical magnetic sectors" (a small heliolatitudinal extension of a spherical magnetized solar wind plasma shell) that travel into the interplanetary space at the solar wind velocity, we calculate the cosmic-ray intensity for different heliographic latitudes as a series of successive intensity drops that all these "spherical magnetic sectors" between the Sun and the heliospheric termination shock cause the unmodulated galactic cosmic-ray intensity. Our results are compared with the Ulysses cosmic-ray measurements obtained during the first pole-to-pole passage from mid-1994 to mid-1995

Induced crystallization in CW laser-irradiated sol-gel deposited titania films

Isothermal annealing of amorphous TiO{sub 2} films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to densify or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress

Transient stress evolution and crystallization in laser-irradiated amorphous titania sol-gel films

Amorphous TiO{sub 2} sol-gel films are irreversibly transformed to a crystalline anatase phase when heated to temperatures in excess of 575 K or subjected to intense pulsed or CW laser irradiation. The laser-induced transformation is initiated as a result of impurity absorption and subsequent heating, and results in densification and relative changes in compressive stress of the film. Isothermally annealed films exhibit a decrease in compressive stress as crystallization proceeds while an increase in compressive stress followed by a decrease in stress is observed when crystallization is laser-induced. Raman spectroscopy has been used to characterize the crystallization ingrowth kinetics and is used in this work as a real time probe of both film temperature and localized stress which can be evaluated from shifts in lattice phonon frequencies measured in real time during laser irradiation. The laser not only induces the phase transformation but excites inelastic Raman scattering from which film stress and temperature can be estimated. A second approach for the determination of these parameters requires incorporation of a thin ruby film between the titania and silica substrate. Here, the wavelength shift of the laser-induced ruby fluorescence can be used to quantify interfacial stress; the fluorescence lifetime measurements are used to determine temperature. The advantages and limitations of these techniques for evaluating transient stress and temperature evolution in thin titania films subjected to CW laser irradiation will be discussed

Simultaneously performed off-pump coronary artery bypass grafting and colectomy: a case report

This is written so as to report the case of a 71-year-old male with a diagnosis of sigmoid adenocarcinoma accompanied by severe coronary artery disease and unstable angina, which was subject to simultaneous surgical treatment. The patient initially underwent an off-pump coronary artery revascularization in order to avoid the complications of cardiopulmonary bypass, providing the opportunity of a colectomy at the same time with the use of safe surgical means. Our case suggests that performing an off-pump bypass procedure prior to cancer surgery can be an appropriate course of action in carefully selected cases

Drainage of Post-Operative Abdominal and Pelvic Abscesses under the Guidance of Computed Tomography

BACKGROUND: Cross sectional imaging and specifically computed tomography (CT) has become the main radiological modality of detecting post-surgical abdominal collections and abscesses. Percutaneous abscess drainage (PAD) has revolutionized the treatment of abscesses, especially of post-surgical abdominal abscesses over the last 25 years; repeat laparotomy is a rare event due to the fact that the success rate of PAD is very high (90-95%) and complications are few (0-10%).OBJECTIVE: The aim of the study is to present our experience in the department of computed tomography of the percutaneous drainage of post-operative abdominal and pelvic abscesses.PATIENTS AND METHODS: During the last two and a half years, 93 post-operative patients were referred to the CT department for drainage of a post-surgical abscess in the abdomen or pelvis at 9-21 days post-operatively due to persistent fever. A total of 95 abscesses were drained; 84 were located in the abdomen and 11 in the pelvis. Abscess diameters ranged between 2 and 12 cm.  A percutaneous drainage technique under CT-guidance was employed in all patients; 98 catheters were placed with use of the Seldinger technique.  A transgluteal paracoccygeal approach was adopted in 11 patients. Aspiration of an intra-loop abscess was performed in 1 patient. The tilted gantry technique was utilized in 2 cases.RESULTS: Eighty-nine (95.7%) patients were successfully treated. In 4 (4.3%) patients the abscesses were partially drained, patients were stabilized and subsequently treated via laparotomy. Complications included inflammation of the skin at the entry site in 4 patients, pneumothorax in 1 patient, and displacement of the catheter in 12 patients, one involving catheter migration into the duodenum.  Major complications did not occur.CONCLUSION: Percutaneous drainage of post-operative abdominal and pelvic abscesses was a safe and effective method of abscess management in our series with a 95.7% success rate and absent major complications. It is currently a widely used procedure, eliminating the need for repeat laparotomy in the majority of patients. Proper catheter management is essential for the successful outcome

Dielectric and absorbate effects on the optical properties of phosphazenes

The optical response of polyphosphazenes can be directly related to the {pi} (out-of-plane) and {pi}{prime} (in-plane) bonding interactions intrinsic to the electronic structure of these materials. Altering this structure either by hydrogen bonding or absorbate effects, affects both the linear and nonlinear optical susceptibilities. In this paper, we have performed electronic structure calculations on the cyclic molecules, P{sub 3}N{sub 3}(NHCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(SCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(OCH{sub 3}){sub 6} and P{sub 4}N{sub 4}(NHCH{sub 3}){sub 8} as model systems for the polymer. Charge distribution arguments are discussed to explain the influence of a polarizing electric field on the {pi} bonding systems, and are used to suggest methods to enhance their nonlinearities