Executing matrix multiply on a process oriented data flow machine

The Process-Oriented Dataflow System (PODS) is an execution model that combines the von Neumann and dataflow models of computation to gain the benefits of each. Central to PODS is the concept of array distribution and its effects on partitioning and mapping of processes.In PODS arrays are partitioned by simply assigning consecutive elements to each processing element (PE) equally. Since PODS uses single assignment, there will be only one producer of each element. This producing PE owns that element and will perform the necessary computations to assign it. Using this approach the filling loop is distributed across the PEs. This simple partitioning and mapping scheme provides excellent results for executing scientific code on MIMD machines. In this way PODS allows MIMD machines to exploit vector and data parallelism easily while still providing the flexibility of MIMD over SIMD for multi-user systems.In this paper, the classic matrix multiply algorithm, with 1024 data points, is executed on a PODS simulator and the results are presented and discussed. Matrix multiply is a good example because it has several interesting properties: there are multiple code-blocks; a new array must be dynamically allocated and distributed; there is a loop-carried dependency in the innermost loop; the two input arrays have different access patterns; and the sizes of the input arrays are not known at compile time. Matrix multiply also forms the basis for many important scientific algorithms such as: LU decomposition, convolution, and the Fast-Fourier Transform.The results show that PODS is comparable to both Iannucci's Hybrid Architecture and MIT's TTDA in terms of overhead and instruction power. They also show that PODS easily distributes the work load evenly across the PEs. The key result is that PODS can scale matrix multiply in a near linear fashion until there is little or no work to be performed for each PE. Then overhead and message passing become a major component of the execution time. With larger problems (e.g., >/=16k data points) this limit would be reached at around 256 PEs

Automatic data/program partitioning using the single assignment principle

Loosely-coupled MIMD architectures do not suffer from memory contention; hence large numbers of processors may be utilized. The main problem, however, is how to partition data and programs in order to exploit the available parallelism. In this paper we show that efficient schemes for automatic data/program partitioning and synchronization may be employed if single assignment is used. Using simulations of program loops common to scientific computations (the Livermore Loops), we demonstrate that only a small fraction of data accesses are remote and thus the degradation in network performance due to multiprocessing is minimal

Variable Ticket Pricing in Major League Baseball

Sport teams historically have been reluctant to change ticket prices during the season. Recently, however, numerous sport organizations have implemented variable ticket pricing in an effort to maximize revenues. In Major League Baseball variable pricing results in ticket price increases or decreases depending on factors such as quality of the opponent, day of the week, month of the year, and for special events such as opening day, Memorial Day, and Independence Day. Using censored regression and elasticity analysis, this article demonstrates that variable pricing would have yielded approximately $590,000 per year in additional ticket revenue for each major league team in 1996, ceteris paribus. Accounting for capacity constraints, this amounts to only about a 2.8$1.4 million in revenue. The largest percentage revenue gain would have been the San Francisco Giants. The Giants would have seen an estimated 6.7% increase in revenue had they used optimal variable pricing

Treatment of Travel Expenses by Golf Course Patrons: Sunk or Bundled Costs and the First and Third Laws of Demand

To attract golf patrons, sport managers must understand consumption patterns of the golfer. Importantly, the treatment of travel costs must be understood. According to the Alchian-Allen (1964) theorem, golfers treat travel costs as bundled costs (third law of economic demand) whereas classical consumer theory indicates that golfers treat travel costs as sunk costs (first law of economic demand). The purpose of this study was to determine if golf patrons treated travel costs as sunk costs or if they treated travel costs as a bundled cost. Data from a survey of course patrons in Ohio support the treatment of travel costs as bundled costs by golf course patrons, especially those classified as tourists. The strong, positive correlation found between distance traveled and the cost of greens fees enables managers to utilize geographic segmentation in choosing to whom to market their course based upon their product’s price compared to area competitors

Coupled Motions Direct Electrons along Human Microsomal P450 Chains

Directional electron transfer through biological redox chains can be achieved by coupling reaction chemistry to conformational changes in individual redox enzymes

Washington 'Redskins' - Disparaging Term or Valuable Tradition?: Legal and Economic Issues Concerning Harjo v. Pro-Football, Inc.

I\u27ll never change the name of the Redskins. You have my word on that. In addition to that, it\u27s really what the Redskins mean that\u27s not quite out there.., what it means is tradition. It means winning. It means a great tradition for the franchise. -Daniel Snyder (owner of the Washington Redskins). A long habit of not thinking a thing wrong gives it a superficial appearance of being right, and raises at first a formidable outcry in defense of custom. -Thomas Paine

Light-evoked Somatosensory Perception of Transgenic Rats That Express Channelrhodopsin-2 in Dorsal Root Ganglion Cells

In vertebrate somatosensory systems, each mode of touch-pressure, temperature or pain is sensed by sensory endings of different dorsal root ganglion (DRG) neurons, which conducted to the specific cortical loci as nerve impulses. Therefore, direct electrical stimulation of the peripheral nerve endings causes an erroneous sensation to be conducted by the nerve. We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain