Memory types

The use of a smectic A LC instead of a nematic LC allows for memory-type H-PDLCs, as shown by Date et al. [25], At an appropriate temperature for the LC used, the grating could be switched off with a 10 ms electric field pulse of 30 V/p,m. In contrast, nematic H-PDLCs require a continuous application of the field to maintain the off state. The smectic H-PDLCs were turned back on by warming them above a critical temperature. 

Fig. 11 shows the photoswitching of the injection current. Upon UV irradiation, the hole injection current increased, while decreasing to zero on irradiation with visible light. Very thin amorphous diarylethene film as thin as 0.2 pm could also control the hole injection to the organic hole transport layer (Fig. 9b). These results are potentially applicable to optical memory-type organic photoconductors.

A strain-biased antiparallel domain configuration is induced in the plane of a memory-type PLZT (7/65/35 with a grain size of 1.5 /mi) plate approximately 60 fim thick, as shown in Fig. 8.17(a). A strain of 10 3 is achieved by bonding the PLZT to a thicker plate of transparent Perspex and bending the combination so that the ceramic is in tension in the convex surface. Combining a photo-conductive layer, e.g. polyvinyl carbazole, CdS, ZnS or selenium, with the PLZT plate allows an optical pattern to be electrically stored, read and erased. Transparent ITO electrodes sandwich the photoconductor-PLZT combination. 

Reconstructive memory— Type of memory thought to store experiences by abstract principles, which are then used to reconstruct memories during recall. 

To load the functions back into memory, type LOAD "filename",%, for disk or lOAD"filename",1,1... 

Physically, memory is a collection of integrated circuits (ICs) that store data and program information as patterns of Is and Os (on and off states) in the chip. Most memory chips require constant power (also called a constant refresh) to maintain those patterns of Is and Os. If power is lost, ail those tiny switches revert back to the off position, effectively erasing the data from memory. Some memory types, however, do not require refresh. 

Which of the following memory types offers the highest transfer rate and bandwidth rate ... 

A. Terminology (e.g., memory types, CPU, baud rates, Internet)... 

In the memory hierarchy, the memory level in the higher location of the pyramid of Fig. 10 is usually physically closer to the processor, faster, more frequently accessed, smaller in size, and each bit is more expensive. Some of the characteristics of memory types are access time, bandwidth, size limit, management responsibility, and location within the computer system (within processor or on the external bus). 

Size, cost, and speed are the major design parameters in the memory hierarchy. The principle behind memory hierarchy design is to keep the cost per unit of memory as close as possible to that of the least expensive memory and keep the average access time as close as possible to that of the fastest memory. To accomplish this, the design must use a minimal amount of the memory type at the top of the pyramid of Fig. 10 and attempt to keep information that will be accessed in the near future in memory at the top of the pyramid. Removable disks and tapes are of unlimited size, and that means that the user may continue to buy more of the media until his needs are met. 

MIMD parallel computers are usually divided into shared and distributed memory types. In the shared memory case, multiple processors are connected to memory by a switch so that any processor can access any memory location, and all processors have access to the same global name space. Thus, when each processor refers to the variable x they are all refering to the same location in the shared memory. The shared memory approach to parallelism is attractive because in porting an application from a sequential to a shared memory parallel computer usually only a few changes are required in the sequential... 

MPP systems, where MPP stands for massively parallel processors, can be of both the shared-memory type and the distributed-memory type. In both of these types, one is confronted with the problem of how to deliver the data from the memory to the processors. An interconnection network is needed that connects the memory or memories, in the case of a distributed memory machine, to the processors. Through the years many types of networks have been devised. Figure 4 shows some types of networks used in present-day MPP systems. 

Saltini C, Kirby M, Trapnell BC, et al. Biased accumulation of T lymphocytes with memory -type CD45 leukocyte common antigen gene expression on the epithelial surface of the human lung. J Exp Med 1990 171(4) 1123-1140. 

Ultrastmctural studies suggest that endothelial and/or epithelial injury precedes inflammation and fibrosis in early SSc-ILD (51). Thereafter, both proliferation of myofibroblasts and the overdevelopment of capillary microvessels seem to be involved in progressive lung fibrosis (66). T lymphocytes may play a fundamental role. T-cell responses to epitopes of DNA topoisomerase I are restricted, both in healthy subjects and in those with SSc (67-69). Thus, the anti-topoisomerase antibody may provoke a pathogenetic immune response in individuals with responsive T-cell clones. Lung tissue of patients with SSc-ILD displays lymphoid follicles with germinal centers and CD4 T cells of both THl and TH2 subsets that express the hallmark profile of cytokines [interleukin-4 (EL-4), EL-5, and y-interferon (INF-y)] in balanced numbers at the mRNA level (10), as well as accumulation of memory type lymphocytes (70). In BAL, patients with SSc-ELD show a predominance of CD8 T cells that produce Th2 cytokines, most notably EL-4, in contrast to those with no ILD (71). 

Very recently a memory type liquid crystal , which has the characteristics of an... 

SmA phase, has also been used to produce a memory type device [80]. Interestingly, this device uses reverse phase PDLC so that a finer line resolution can be obtained, reversal of the process being of no importance. This device consists of a thin (6 p,m) film of memory type liquid crystal and has submicrometer sized polymer balls dispersed within it and then a polymer skin on top to give-a memory type liquid crystal polymer composite (M-LCPC) (Fig. 13). 

Figure 13. Submicrometer polymer balls in a continuum of memory type liquid crystal and a polymer cover film.

Date, M., Takeuchi, Y., Kato, K. A memory-type holographic polymta- dispersed liquid crystal (HPDLC) reflective display device. J. Phys. D Appl. Phys. 31, 2225 (1998)... 

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