Activation of Long Descending Propriospinal Neurons in Cat Spinal Cord

Isolated mammalian spinal cord has been shown capable of generating locomotor activity. Propriospinal systems assumed to coordinate fore- and hindlimb activity are poorly understood. This study characterizes the long descending propriospinal (LDP) neurons in terms of the location of the somas and their peripheral inputs by direct neuronal recording. Anatomical studies using axonal retrograde transport of horseradish peroxidase from the lumbar to the cervical spinal cord as a tracer first described these neurons. Two hundred and thirty-one LDP neurons were identified in electrophysiological experiments. Of these, 123 responded to natural stimulation, and about 50% of the others were activated only by electrical stimulation. The majority of cells were located in laminae VII and VIII in agreement with anatomical data. The most effective stimuli were mechanical stimulation of skin, deep pressure to subcutaneous tissues, and paw joint movement. Bot excitatory and inhibitory responses were observed

On evaluating parallel computer systems

A workshop was held in an attempt to program real problems on the MIT Static Data Flow Machine. Most of the architecture of the machine was specified but some parts were incomplete. The main purpose for the workshop was to explore principles for the evaluation of computer systems employing new architectures. Principles explored were: (1) evaluation must be an integral, ongoing part of a project to develop a computer of radically new architecture; (2) the evaluation should seek to measure the usability of the system as well as its performance; (3) users from the application domains must be an integral part of the evaluation process; and (4) evaluation results should be fed back into the design process. It is concluded that the general organizational principles are achievable in practice from this workshop

Economic profile of Florida's marine life industry

The marine life industry in Florida is defined as the harvest of live marine specimens (fish and invertebrate species including plants, live rock and sand, and small “critters”) for commercial use, primarily aquariums. This paper summarizes data collected on the industry since 1990, including total landings, revenues, and trends over time. Regional analysis shows where the primary collecting areas are located in Florida. Seasonal analysis shows when the majority of landings occur within the year. Statistics on the number of participants by type (i.e., collector versus wholesaler) provide insight into the size of the industry. Trends are evaluated in terms of changes across the 9-year period from 1990 to 1998. In general, the number of licensed collectors has increased substantially, landings of fish and animal invertebrates peaked in 1994, angelfish dominated the fish landings, live rock dominated the invertebrate landings, and the average landings per trip have remained relatively constant. (67pp.

Aquaculture and marketing of the Florida Bay Scallop in Crystal River, Florida

The overall goal of this study was to develop a new fishery resource product through open-water aquaculture for the west coast of Florida that would compete as a non-traditional product through market development. Specific objectives were as follows: I. To grow a minimum of 50, 000 juvenile scallops to a minimum market size of40 mm in a cage and float system in the off-shore waters of Crystal River, Florida. 2. To determine the growth rate, survival, and time to market size for the individuals in this system and area to other similar projects like Virginia. 3. To introduce local fishermen and the aquaculture students at Crystal River High School to the hatchery, nursery, and grow-out techniques. 4. To determine the economic and financial characteristics of bay scallop culture in Florida and assess the sensitivity of projected costs and earnings to changes in key technical, managerial, and market related parameters. 5. To determine the market acceptability and necessary marketing strategy for whole bay scallop product in Florida. (PDF has 99 pages.

1999 US tropical fish wholesaler survey: results and implications

A survey of marine life wholesalers was initiated in 1999 as a first step towards understanding the nature of Florida’s marine life industry, the demand for Florida products, and the need for changes in the way the industry is regulated. Florida firms deal primarily in marine species and collect much of their own product. Wholesalers outside of Florida handle more freshwater species and purchase most of their inventory, the majority from overseas suppliers. Dealers predict that the average firm size will continue to grow as the industry consolidates. Niche markets for eco-friendly product will gain momentum. In Florida, marketing strategies should point to the high quality of Florida species with emphasis on the growing popularity of invertebrates. Wholesalers should look to provide buyers of Florida product with more consistent quantities throughout the year. Resource managers will be challenged to find ways to protect over-harvested species without interfering with the collection of abundant species while considering the effect of new regulations. (42pp.

Aquiculture and Marketing of the Florida Bay Scallop in Crystal River, Florida

The overall goal of this study was to develop a new fishery resource product through open-water aquaculture for the west coast of Florida that would compete as a non-traditional product through market development. Specific objectives were as follows: I. To grow a minimum of 50, 000 juvenile scallops to a minimum market size of40 mm in a cage and float system in the off-shore waters of Crystal River, Florida. 2. To determine the growth rate, survival, and time to market size for the individuals in this system and area to other similar projects like Virginia. 3. To introduce local fishermen and the aquaculture students at Crystal River High School to the hatchery, nursery, and grow-out techniques. 4. To determine the economic and financial characteristics of bay scallop culture in Florida and assess the sensitivity of projected costs and earnings to changes in key technical, managerial, and market related parameters. 5. To determine the market acceptability and necessary marketing strategy for whole bay scallop product in Florida. (PDF has 99 pages

Computation of nucleation of a non-equilibrium first-order phase transition using a rare-event algorithm

We introduce a new Forward-Flux Sampling in Time (FFST) algorithm to efficiently measure transition times in rare-event processes in non-equilibrium systems, and apply it to study the first-order (discontinuous) kinetic transition in the Ziff-Gulari-Barshad model of catalytic surface reaction. The average time for the transition to take place, as well as both the spinodal and transition points, are clearly found by this method.Comment: 12 pages, 10 figure

On the mechanical properties of N-functionalised dipeptide gels

The properties of a hydrogel are controlled by the underlying network that immobilizes the solvent. For gels formed by the self-assembly of a small molecule, it is common to show the primary fibres that entangle to form the network by microscopy, but it is difficult to access information about the network. One approach to understand the network is to examine the effect of the concentration on the rheological properties, such that G cx, where G is the storage modulus and c is the concentration. A number of reports link the exponent x to a specific type of network. Here, we discuss a small library of gels formed using functionalized dipeptides, and describe the underlying networks of these gels, using microscopy, small angle scattering and rheology. We show that apparently different networks can give very similar values of x

Water quality evaluation of regionalized wastewater systems

U.S. Department of the InteriorU.S. Geological SurveyOpe