Nonvolatile storage in photorefractive crystals

We propose and demonstrate a nonvolatile holographic recording system for storing two-dimensional images. The readout light in this system is not absorbed by the holographic medium, and the data are preformatted or postformatted so that lines from different holograms are interleaved to satisfy the Bragg-matching condition

Real-time computer-generated hologram by means of liquid-crystal television spatial light modulator

A novel use of liquid-crystal television (LCTV) is described. It is shown that, if the phase nonuniformity of the LCTV is corrected by a liquid gate, then a simple computer-generated hologram can be written and coherently reconstructed

Large-scale Holographic Memory: Experiment Results

We describe a holographic optical memory capable of storing up to 10^12 bits of information. The stored information is retrieved in blocks or pages, each consisting of 10^3 x 10^3 bits. Each page can be accessed randomly in approximately 100 µsec with an experimentally measured SNR of 816.8, and a projected probability of error of 10^(-28)

Star Formation and Environmental Quenching of Group Galaxies from the GEEC2 Survey at z~1

This work presents detailed analysis from the GEEC2 spectroscopic survey of galaxy groups at 0.8 66 per cent) for eight of the eleven groups. Using an optical-NIR colour-colour diagram, the galaxies in the sample are separated with a dust insensitive method into the three categories, star-forming, quiescent, and intermediate. The strongest environmental dependence is observed in the fraction of quiescent galaxies, which is higher inside groups than in the field for all stellar masses. While intermediate galaxies represent ~15-20 per cent of the star-forming population in both the group and field, the average specific star formation rates (sSFR) of the group population is lower by a factor of ~3. The intermediate population also does not show the strong Hδ absorption that is characteristic of starburst galaxies. Inside groups, only 4.4-6.7 per cent of star-forming galaxies are starbursts, which gives additional validity to the assumption that the quenching of star-formation is the primary process in the transition from the star-forming to the quiescent state. With the use of stellar synthesis models, two possible scenarios for the origins of the intermediate population are investigated, including the quenching of star-forming galaxies via environmental processes and the rejuvenation of star formation in early-type galaxies via mixed mergers. To model the quenching scenario, we have tested the use of different exponential quenching timescales (τ_2) and different types of delays between satellite accretion and the onset of quenching. We found that the fraction of intermediate galaxies depends most strongly on the value of τ_2. The relative fractions of galaxies rule out both the no-delay scenario, which would require a long τ_2 that over-produces intermediate galaxies, as well as the constant 3 Gyr delay model, which does not produce a sufficient number of quiescent galaxies. The observed fractions are best matched with a model that includes a dynamical delay time and a τ_2=0.25 Gyr, but this model also predicts intermediate galaxies Hδ strength higher than that observed. For the rejuvenation scenario, we found that the time visible in the intermediate region is directly related to the size of the second 'burst' of star-formation, which can then be further constrained by the Hδ strength for the intermediate population. The observations are best matched to a burst size of ~1 per cent, at a rate of ~3 times per Gyr. In order to properly distinguish between the two scenarios, we will need to both increase the signal-to-noise ratio for the Hδ measurements and conduct a deeper survey of satellite galaxies both inside groups and in the field

Techniques for writing and reading data on an optical disk which include formation of holographic optical gratings in plural locations on the optical disk

An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created, and subsequently detected, at plural locations within the disk by an electro-optical head. Creation and detection of holographic gratings with variable diffraction efficiency is possible with the electro-optical head. Multiple holographic gratings can also be created at each one of the plural locations via a beam of light which has a different wavelength or point of focus. These data elements can be read by the electro-optical head using a beam of light sequentially varied in wavelength or point of focus to correspond to the multiple holographic gratings to be recorded

Holographic optical disc

The holographic disc is a high capacity, disk-based data storage device that can provide the performance for next generation mass data storage needs. With a projected capacity approaching 1 terabit on a single 12 cm platter, the holographic disc has the potential to become a highly efficient storage hardware for data warehousing applications. The high readout rate of holographic disc makes it especially suitable for generating multiple, high bandwidth data streams such as required for network server computers. Multimedia applications such as interactive video and HDTV can also potentially benefit from the high capacity and fast data access of holographic memory

Optical memory for computing and information processing

The high data transfer rate achievable in page-oriented optical memories demands for parallel interfaces to logic circuits able to process efficiently the data. The Optically Programmable Gate Array, an enhanced version of a conventional FPGA, utilizes a holographic memory accessed by an array of VCSELs to program its logic. Combining spatial and shift multiplexing to store the configuration pages in the memory, the OPGA module is very compact and has extremely short configuration time allowing for dynamic reconfiguration. The reconfiguration capability of the OPGA can be applied to solve more efficiently problems in pattern recognition and digit classification

System metric for holographic memory systems

We show that the oxidation state of Fe in LiNbO3 has two competing effects on the diffraction efficiency of multiple holograms in 90 degrees-geometry holographic storage. For crystals with moderate absorption, the saturation space-charge field is larger after high-temperature reduction treatment. However, reduction also increases absorption, which reduces the overall diffraction efficiency. We develop a theoretical model that predicts achievable diffraction efficiency as a function of oxidation state, doping level, photovoltaic field, crystal length, and region of beam overlap. We compare this model with experimental results for achievable diffraction efficiency and erasure-time constant. (C) 1996 Optical Society of Americ

System metric for holographic memory systems

We introduce M/# as a metric for characterizing holographic memory systems. M/# is the constant of proportionality between diffraction efficiency and the number of holograms squared. Although M/# is a function of many variables in a holographic recording system, it can be measured from the recording and erasure of a single hologram. We verify experimentally that the diffraction efficiency of multiple holograms follows the prediction of M/# measured from a single hologram

Immunotherapeutic Approaches of Rheumatoid Arthritis and the Implication on Novel Interventions for Refractoriness

Rheumatoid arthritis is an autoimmune disorder involving the chronic inflammation of affected joints which lead to the distortion and eventually destruction of the articular tissues. Clinically, many therapeutic methods are being used for RA treatment. Non-steroidal anti-inflammatory drugs (NSAIDs), steroid, and disease-modifying anti-rheumatic drugs (DMARDs) are the three main categories of intervention approaches. Among which DMARDs, targeting mainly the release of pro-inflammatory cytokines, demonstrated high efficacy because of its direct drug action that alter the underlying disease mechanisms rather than simply to mediate symptoms relieve. However, the use of DMARDs also accompanying some unwanted adverse side effects, in particular, the development of refractoriness, which hampers the successful rate of treatment. In this chapter, the conventional RA drugs will be reviewed, focusing on the currently used and latest development of DMARDs. Novel methods that could improve RA pathogenesis will also be introduced. Because of the critical role of refractory RA, the progress of the disease to develop resistance to standard drug treatment will also be described. Finally, innovative RA therapeutic methods inspired by researches concerning the pathogenesis and contemporary treatments of RA will be discussed