A blood vessel model constructed from collagen and cultured vascular cells

A model of a blood vessel was constructed in vitro. Its multilayered structure resembled that of an artery and it withstood physiological pressures. Electron microscopy showed that the endothelial cells lining the lumen and the smooth muscle cells in the wall were healthy and well differentiated. The lining of endothelial cells functioned physically, as a permeability barrier, and biosynthetically, producing von Willebrand's factor and prostacyclin. The strength of the model depended on its multiple layers of collagen integrated with a Dacron mesh.     

Multis: a new class of multiprocessor computers

Multis are a new class of computers based on multiple microprocessors. The small size, low cost, and high performance of microprocessors allow the design and construction of computer structures that offer significant advantages in manufacture, price-performance ratio, and reliability over traditional computer families. Currently, commercial multis consist of 4 to 28 modules, which include microprocessors, common memories, and input-output devices, all of which communicate through a single set of wires called a bus. Adding microprocessors together increases the performance of multis in direct proportion to their price and allows multis to offer a performance range that spans that of small minicomputers to mainframe computers. Multis are commercially available for applications ranging from real-time industrial control to transaction processing. Traditional batch, time-sharing, and transaction systems process a number of independent jobs that can be distributed among the microprocessors of a multi with a resulting increased throughput (number of jobs completed per unit of time). Many scientific applications (such as the solving of partial differential equations) and engineering applications (such as the checking of integrated circuit designs) are speeded up by this parallel computation; thus, multis produce results at supercomputer speed but at a fraction of the cost. Multis are likely to be the basis for the next, the fifth, generation of computers-a generation based on parallel processing.     

Cooling, heating, generating power, and recovering waste heat with thermoelectric systems

Thermoelectric materials are solid-state energy converters whose combination of thermal, electrical, and semiconducting properties allows them to be used to convert waste heat into electricity or electrical power directly into cooling and heating. These materials can be competitive with fluid-based systems, such as two-phase air-conditioning compressors or heat pumps, or used in smaller-scale applications such as in automobile seats, night-vision systems, and electrical-enclosure cooling. More widespread use of thermoelectrics requires not only improving the intrinsic energy-conversion efficiency of the materials but also implementing recent advancements in system architecture. These principles are illustrated with several proven and potential applications of thermoelectrics.     

Drug prevention in junior high: a multi-site longitudinal test

Results from a longitudinal experiment to curb drug use during junior high indicate that education programs based on a social-influence model can prevent or reduce young adolescents' use of cigarettes and marijuana. This multi-site experiment involved the entire seventh-grade cohort of 30 junior high schools drawn from eight urban, suburban, and rural communities in California and Oregon. Implemented between 1984 and 1986, the curriculum's impact was assessed at 3-, 12-, and 15-month follow-ups. The program, which had positive results for both low- and high-risk students, was equally successful in schools with high and low minority enrollment. However, the program did not help previously confirmed smokers and its effects on adolescent drinking were short-lived.     

Supernova shock breakout from a red supergiant

Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic "core-collapse" supernova. Such events are usually only detected at least a few days after the star has exploded. Observations of the supernova SNLS-04D2dc with the Galaxy Evolution Explorer space telescope reveal a radiative precursor from the supernova shock before the shock reached the surface of the star and show the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve confirm that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a way to probe the physics of core-collapse supernovae and the internal structures of their progenitor stars.     

Ultrahigh pressure: beyond 2 megabars and the ruby fluorescence scale

A new design of the diamond-window, high-pressure cell has permitted static pressure of 2.8 megabars to be generated for the first time. The design is unusually stable mechanically, and thus it should be possible to use the new cell to study most materials, including hydrogen, in the unexplored pressure region above 1 megabar.