Parallel Optical Random Access Memory (PORAM)

It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components

Read-write holographic memory with iron-doped lithium niobate

The response of iron doped lithium niobate under conditions corresponding to hologram storage and retrieval is described, and the material's characteristics are discussed. The optical sensitivity can be improved by heavy chemical reduction of lightly doped crystals such that most of the iron is in the divalent state, the remaining part being trivalent. The best reduction process found to be reproducible so far is the anneal of the doped crystal in the presence of a salt such as lithium carbonate. It is shown by analysis and simulation that a page-oriented read-write holographic memory with 1,000 bits per page would have a cycle time of about 60 ms and a signal-to-noise ratio of 27 db. This cycle time, although still too long for a practical system, represents an improvement of two orders of magnitude over that of previous laboratory prototypes using different storage media

Alien Registration- Poulin, Alphonse G. (Millinocket, Penobscot County)

https://digitalmaine.com/alien_docs/7377/thumbnail.jp

Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Platinum/ceria/alumina catalysts have been prepared by a sol–gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400°C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N2 adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86 kJ/mol has been found and at 260 °C the TOF corresponds to 0.6 ± 0.1 s−1 for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization

Linear laser diode arrays for improvement in optical disk recording for space stations

The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated

Improving the Reliability and Modal Stability of High Power 870 nm AlGaAs CSP Laser Diodes for Applications to Free Space Communication Systems

The operating characteristics (power-current, beam divergence, etc.) and reliability assessment of high-power CSP lasers is discussed. The emission wavelength of these lasers was optimized at 860 to 880 nm. The operational characteristics of a new laser, the inverse channel substrate planar (ICSP) laser, grown by metalorganic chemical vapor deposition (MOCVD), is discussed and the reliability assessment of this laser is reported. The highlights of this study include a reduction in the threshold current value for the laser to 15 mA and a degradation rate of less than 2 kW/hr for the lasers operating at 60 mW of peak output power

Intracavity Gain And Absorption Dynamics Of Hybrid Modelocked Semiconductor Lasers Using Multiple Quantum Well Saturable Absorbers

Time resolved intracavity gain, saturable absorption dynamics, intracavity intensity pulse profiles, and their corresponding spectrograms, were measured in an external cavity hybrid mode-locked semiconductor diode laser. These measurements were performed to obtain fundamental information of the mode-locking dynamics and to determine their role in the pulse shaping and chirping dynamics. The results of these experiments show that the integrating nonlinearity associated with gain depletion, coupled with group velocity dispersion, leads to asymmetric intensity pulse profiles with predominantly cubic temporal phase, while saturable absorption coupled with group velocity dispersion tends to linearize the chirp. Exploitation of these dynamics may allow researchers to generate optical pulses with higher peak intensities than previously reported

Geographic distribution, age pattern and sites of lesions in a cohort of buruli ulcer patients from the mapé basin of cameroon

Buruli ulcer (BU), a neglected tropical disease of the skin, caused by Mycobacterium ulcerans, occurs most frequently in children in West Africa. Risk factors for BU include proximity to slow flowing water, poor wound care and not wearing protective clothing. Man-made alterations of the environment have been suggested to lead to increased BU incidence. M. ulcerans DNA has been detected in the environment, water bugs and recently also in mosquitoes. Despite these findings, the mode of transmission of BU remains poorly understood and both transmission by insects or direct inoculation from contaminated environment have been suggested. Here, we investigated the BU epidemiology in the Mapé basin of Cameroon where the damming of the Mapé River since 1988 is believed to have increased the incidence of BU. Through a house-by-house survey in spring 2010, which also examined the local population for leprosy and yaws, and continued surveillance thereafter, we identified, till June 2012, altogether 88 RT-PCR positive cases of BU. We found that the age adjusted cumulative incidence of BU was highest in young teenagers and in individuals above the age of 50 and that very young children (>5) were underrepresented among cases. BU lesions clustered around the ankles and at the back of the elbows. This pattern neither matches any of the published mosquito biting site patterns, nor the published distribution of small skin injuries in children, where lesions on the knees are much more frequent. The option of multiple modes of transmission should thus be considered. Analyzing the geographic distribution of cases in the Mapé Dam area revealed a closer association with the Mbam River than with the artificial lake

La Favorita

De cada obra s'ha digitalitzat un programa sencer. De la resta s'han digitalitzat les parts que són diferents.Empresa Juan A. PamiasÒpera de Gaetano Donizetti i llibret de Royer i Wae