Appearance of circularly polarized light in an atmosphere-ocean system.

Using a Monte Carlo algorithm to simulate the scattering of sunlight in an atmosphere-ocean system, the degree of circular polarization of light in the ocean has been calculated at multiple depths and directions. In this system circularly polarized light is produced by the reflection of light from beneath the surface at an incident angle greater than the critical angle. We present the results of these simulations for different solar angles, wavelengths of light, and models that include the presence of aerosols in the atmosphere and hydrosols in the water.

Observation of non-principal plane neutral points in the upwelling polarized light field above a water surface.

Using a digital camera and linearly polarizing film, we have developed a method for observing neutral point locations in the natural light field of the atmosphere. Utilizing this method, we have observed neutral points in the upwelling light field above a water surface. We report the location of these neutral points and compare them to Monte Carlo simulations.

Neutral points in an atmosphere-ocean system. 2: Downwelling light field.

We use a Monte Carlo code that calculates the complete Stokes vector to predict the degree of polarization in the complete observable solid angle at any level in an atmosphere-ocean system. Using the Stokes vector components, we can find the positions of neutral points in a simulated plane-parallel atmosphere-ocean system for various conditions. We examine the locations and behavior of these neutral points for an observer placed directly above and beneath the air-water boundary and show how their positions are influenced by different atmospheric and oceanic conditions.

Management of effort thrombosis of the subclavian vein: today's treatment.

"Spontaneous" subclavian vein ("effort") thrombosis is usually related to extrinsic compression of the vein at the costoclavicular junction. Our experience with this entity over the past decade was reviewed with specific focus on the role of thrombolysis and our selection algorithm. All patients treated for this problem at the University of Rochester over the past decade were identified and records retrospectively reviewed. From 1996 to June 2006, a total of 34 patients with spontaneous complete occlusion of the subclavian vein documented by venography were treated, half with a history of an antecedent exertional factor. Catheter-directed thrombolysis prior to planned immediate thoracic outlet decompression (TOD) was performed in 26 patients, while TOD alone was performed in eight. Time since onset of symptoms was the major factor influencing the decision, being a mean of 5.5 days in the 26 referred for lysis but 1 month to many years in the group who underwent surgery alone. In patients undergoing lysis, flow was restored in 16 (62%), of whom nine had a residual lesion. All but two of the 26 who received thrombolysis then underwent TOD with or without angioplasty, and 13 underwent venous reconstruction as well (eight of the 16 in whom patency had been restored and five of eight in whom it had not). Patients not undergoing lysis were managed by TOD, with five (62%) undergoing decompression alone and three (38%) undergoing formal venous reconstruction. Thrombolysis was not attempted (eight) or unsuccessful (four) in all 12 patients whose symptoms had been present for more than 14 days at presentation. At mean follow-up of 33 months, symptom resolution was almost universal. Primary patency at 5 years was 84% in the thrombolysis group and 83% in the TOD-only group. In conclusion, the primary factor influencing treatment choice at our institution has been time since onset of symptoms. Patients presenting soon after symptom onset underwent thrombolysis followed by TOD, while patients presenting with chronic symptoms underwent TOD alone; in both cases venous reconstruction was based on residual findings after lysis. We have not had successful thrombolysis in a patient presenting with 14 days or more of symptoms. While optimal therapy cannot be defined based on this retrospective review, our algorithm resulted in excellent overall long-term patency and symptom relief.

Comparison of radiance and polarization values observed in the Mediterranean Sea and simulated in a Monte Carlo model.

Measurements of the radiance and degree of polarization made in 1971 in the Mediterranean Sea are presented along with the simulation of all observed quantities by a Monte Carlo technique. It is shown that our independent scattering treatment utilizing a Stokes vector formalism to describe the polarization state of the light field produces remarkably good agreement with those values measured in situ.