Optical spin Hall effects in plasmonic chains

Observation of optical spin Hall effects (OSHEs) manifested by a spin-dependent momentum redirection is presented. The effect occurring solely as a result of the curvature of the coupled localized plasmonic chain is regarded as the locally isotropic OSHE, while the locally anisotropic OSHE arises from the interaction between the optical spin and the local anisotropy of the plasmonic mode rotating along the chain. A wavefront phase dislocation was observed in a circular curvature, in which the dislocation strength was enhanced by the locally anisotropic effect.     

Carbon cycling in a zero-discharge mariculture system

Interest in mariculture systems will rise in the near future due to the decreased ability of the ocean to supply the increasing demand for seafood. We present a trace study using stable carbon and nitrogen isotopes and chemical profiles of a zero-discharge mariculture system stocked with the gilthead seabream (Sparus aurata). Water quality maintenance in the system is based on two biofiltration steps. Firstly, an aerobic treatment step comprising a trickling filter in which ammonia is oxidized to nitrate. Secondly, an anaerobic step comprised of a digestion basin and a fluidized bed reactor where excess organic matter and nitrate are removed. Dissolved inorganic carbon and alkalinity values were higher in the anaerobic loop than in the aerobic loop, in agreement with the main biological processes taking place in the two treatment steps. The δ¹³C of the dissolved inorganic carbon (δ¹³C_DIC) was depleted in ¹³C in the anaerobic loop as compared to the aerobic loop by 2.5-3‰. This is in agreement with the higher dissolved inorganic carbon concentrations in the anaerobic loop and the low water retention time and the chemolithotrophic activity of the aerobic loop. The δ¹³C and δ¹⁵N of organic matter in the mariculture system indicated that fish fed solely on feed pellets. Compared to feed pellets and particulate organic matter, the sludge in the digestion basin was enriched in ¹⁵N while δ¹³C was not significantly different. This latter finding points to an intensive microbial degradation of the organic matter taking place in the anaerobic treatment step of the system.     

Acute fungal endocarditis due to Trichosporon beigelli]

We report a 59-year-old woman with acute fungal endocarditis of a prosthetic valve caused by the endogenic organism, Trichosporon beigelli. This slowly developing disease mainly effects drug addicts who use intravenous narcotics. In nonaddicts it is rare, with mortality as high as 50%. There are only sporadic reports of T. beigelli as a complication long after open heart surgery. The ongoing infection is undetected for even years after the primary infection, due to its prolonged latent phase. We present the difficulties of diagnosis, and of treating the disease with a combination of surgery and of long-term chemotherapy.     

A copper laser using CuI vapor

A simple CuI double-pulsed laser was built. The dependence of power output on the delay between the two excitation pulses, temperature, and the type of buffer gas has been investigated. The laser pulse duration was measured.     

Buffer gas effect on ground and metastable populations in a pulsed CuBr laser

We have measured the time dependence of the concentration of copper atoms in the ground and metastable states in a pulsed CuBr laser by monitoring the absorption of the atomic copper lines 244.2 and 510.6 nm. In agreement with previous measurements in a CuCl laser, we found the populations to grow after the dissociation pulse, peaking many tens of microseconds later. Temperature and buffer gas species and pressure have a considerable influence on the details of the temporal evolution. The results are interpreted in terms of a schematic mechanism involving parallel dissociation processes. Qualitative agreement with the experimental results is quite good, but no attempt was made to elucidate the physical processes which actually occur during and after the dissociation pulse. In the course of the experiment the radiative transition probability of the 244.2 nm line was measured and found to be0.26 times 10^{-7}s^-1.     

Software monitoring with controllable overhead

We introduce the technique of software monitoring with controllable overhead (SMCO), which is based on a novel combination of supervisory control theory of discrete event systems and PID-control theory of discrete time systems. SMCO controls monitoring overhead by temporarily disabling monitoring of selected events for as short a time as possible under the constraint of a user-supplied target overhead o _t. This strategy is optimal in the sense that it allows SMCO to monitor as many events as possible, within the confines of o _t. SMCO is a general monitoring technique that can be applied to any system interface or API. We have applied SMCO to a variety of monitoring problems, including two highlighted in this paper: integer range analysis, which determines upper and lower bounds on integer variable values; and non-accessed period detection, which detects stale or underutilized memory allocations. We benchmarked SMCO extensively, using both CPU- and I/O-intensive workloads, which often exhibited highly bursty behavior. We demonstrate that SMCO successfully controls overhead across a wide range of target overhead levels; its accuracy monotonically increases with the target overhead; and it can be configured to distribute monitoring overhead fairly across multiple instrumentation points.     

Improving the multicommodity flow rates with network codes for two sources

In this work we introduce a construction and analysis of network codes for two sources. The region of achievable rates for this problem is still unknown. The scheme we suggest is based on modifying the multicommodity flow solution and thus improving the achievable rate region, w.r.t the uncoded case. The similarity to the flow problem allows our method to be implemented distributively. We show how the construction algorithm can be combined with distributed backpressure routing algorithms for wireless ad-hoc networks. For both the nondistributed case and the distributed case, the computational complexity of our algorithm for network coding is comparable to that of the parallel multicommodity flow problem. We provide non trivial upper and lower bounds on the performance of our scheme, using random coding techniques.     

Direct demodulation of Hartmann-Shack patterns

Hartmann-Shack wave-front sensors produce a distorted grid of spots whose deviation from perfection is linear with the wave-front gradient. Usually, the centroid of each spot is calculated to provide that deviation, but it is also possible to perform the calculation by Fourier demodulation of the spot pattern [Opt. Commun. 215, 285, 2003]. We show that this demodulation can be performed directly on the grid, without reverting to Fourier transforms. Tracking the motion of each centroid individually is limited to well-defined spots with motions smaller than their pitch. In contrast, our method treats the image as a whole, is not limited to non-overlapping or sharp spots, and allows large spot motions. By replicating the array of spots slightly beyond the edge of the aperture, we reduce the chance for boundary phase dislocations in the reconstruction of the wave front. The method is especially suited to very large arrays.