Magnetic contribution to the interdiffusion coefficients in bcc (<Emphasis Type="Italic">α</Emphasis>) and fcc (<Emphasis Type="Italic">γ</Emphasis>) Fe-Ni alloys

The interdiffusion coefficients in bcc (α) and fcc (γ) Fe-Ni alloys below their Curie temperatures have been calculated based on the magnetic contribution to the free energy for interdiffusion. The free energy for interdiffusion due to magnetic ordering in bcc Fe-Ni alloys is positive. The calculated interdiffusion coefficients in bcc Fe-Ni alloys fit the experimental data quite well. In fcc Fe-Ni alloys, the magnetic contribution to interdiffusion depends on both temperature and composition and is abnormal for Ni compositions in the Invar region. The free energy of vacancy formation is positive and the free energy of vacancy migration is negative, due to the effect of magnetic ordering. The interdiffusion coefficient in the ferromagnetic phase is lower than that extrapolated from the paramagnetic phase for Ni compositions of 50 at. pct and greater and is higher than that extrapolated from the paramagnetic phase for Ni compositions of 40 at. pct and lower.     

A transactional runtime system for the Cell/BE architecture

Single-core architectures have hit the end of the road and industry and academia are currently exploiting new multicore design alternatives. In special, heterogeneous multicore architectures have attracted a lot of attention but developing applications for such architectures is not an easy task due to the lack of appropriate tools and programming models. We present the design of a runtime system for the Cell/BE architecture that works with memory transactions. Transactional programs are automatically instrumented by the compiler, shortening development time and avoiding synchronization mistakes usually present in lock-based approaches (such as deadlock). Experimental results conducted with a prototype implementation and the STAMP benchmark show good scalability for applications with moderate to low contention levels, and whose transactions are not too small. For those cases in which a small performance loss is admissible, we believe that the ease of programming provided by transactions greatly pays off.     

Microstructure and mechanical properties of Sn-In and Sn-Bi solders

This article presents information that helps to clarify the behavior of lead-free, low-melting, eutectic Sn-In and Sn-Bi solders. The Sn-Bi solder forms a well-defined eutectic microstructure at all solidification rates, while Sn-In solder forms an irregular eutectic that changes to a fine-grained two-phase mixture at high solidification rates. Both solders wet copper by forming tin-containing intermetallics; however, Sn-In forms Sn-In-Cu intermetallics with copper and Au-In intermetallics with gold. The steady-state creep behavior of Sn-In and Sn-Bi roughly resembles that of Sn-Pb with similar microstructures. Sn-Bi further resembles Sn-Pb in that its eutectic microstructure recrystallizes within inhomogeneous shear bands. This is not observed in Sn-In. Both Sn-Bi and Sn-In exhibit pronounced strain softening during shear deformation and show early transitions to tertiary creep. Shear stress-strain behavior at normal temperatures and moderate strain rates is governed by creep; the ultimate shear stress can be inferred from the steady-state creep behavior.     

A method to measure the degree of control per se in the oral glucose tolerance test

Using the glucose and insulin values from a 5-hr oral glucose tolerance test, nine quantitative measures have been developed to separate normal, "flat-curve," and non-insulin-dependent diabetic (NIDD) patients. The purpose of these measures is to quantify per se the degree of control operating in glucose homeostasis. A control index which is based upon Swan's minimizing principle and uses only the glucose values was successful in assessing the degree of control operating in glucose homeostasis.     

Boron Carbide–Zirconium Boride In Situ Composites by the Reactive Pressureless Sintering of Boron Carbide–Zirconia Mixtures

The heating of B₄C–YTZP (where YTZP denotes yttria-stabilized zirconia polycrystals) mixtures, under an argon atmosphere, generates B₄C–ZrB₂ composites, because of a low-temperature (<1500°C) carbide–oxide reaction. Composites derived from mixtures that include ≥15% YTZP are better sintered than monolithic B₄C that has been fired under the same conditions. Firing to ∼2160°C (1 h dwell) generates specimens with a bulk density of ≥91% of the theoretical density (TD) for cases where the initial mixture includes ≥15% YTZP. Mixtures that include 30% YTZP allow a fired density of ≥97.5% TD to be attained. The behavior of the B₄C–YTZP system is similar to that of the B₄C–TiO₂ system. Dense B₄C–ZrB₂ composites attain a hardness (Vickers) of 30–33 GPa.     

Epistemic Mediation: Aligning Expertise across Boundaries within an Endangered Species Habitat Conservation Plan

This paper uses videotaping and discourse analysis to study participants' dialogue and conduct during preparation of the Coachella Valley habitat conservation plan in southern California. The research uses social worlds analysis to reveal that the plan's technical advisors did not find facts through the collective discovery of scientific truths with unitary meanings, but instead constructed facts by aligning professional visions of space, time, and agency. The validity of the resulting plan relied on its ability to be a “boundary object”, meaning different things to different groups, while simultaneously laying claim to universality and objectivity. However, its subsequent failure to satisfy an unexpected scientific peer review demonstrates the importance of anticipating downstream reception and use when developing such documents. This case study shows that planners can be epistemic mediators, creating and stabilizing technical knowledge claims that project authority by showing a responsive face to many audiences.     

Three new dominant drug resistance cassettes for gene disruption in Saccharomyces cerevisiae.

Disruption-deletion cassettes are powerful tools used to study gene function in many organisms, including Saccharomyces cerevisiae. Perhaps the most widely useful of these are the heterologous dominant drug resistance cassettes, which use antibiotic resistance genes from bacteria and fungi as selectable markers. We have created three new dominant drug resistance cassettes by replacing the kanamycin resistance (kan(r)) open reading frame from the kanMX3 and kanMX4 disruption-deletion cassettes (Wach et al., 1994) with open reading frames conferring resistance to the antibiotics hygromycin B (hph), nourseothricin (nat) and bialaphos (pat). The new cassettes, pAG25 (natMX4), pAG29 (patMX4), pAG31 (patMX3), pAG32 (hphMX4), pAG34 (hphMX3) and pAG35 (natMX3), are cloned into pFA6, and so are in all other respects identical to pFA6-kanMX3 and pFA6-kanMX4. Most tools and techniques used with the kanMX plasmids can also be used with the hph, nat and patMX containing plasmids. These new heterologous dominant drug resistance cassettes have unique antibiotic resistance phenotypes and do not affect growth when inserted into the ho locus. These attributes make the cassettes ideally suited for creating S. cerevisiae strains with multiple mutations within a single strain.     

Nonphotolithographic nanoscale memory density prospects

Technologies are now emerging to construct molecular-scale electronic wires and switches using bottom-up self-assembly. This opens the possibility of constructing nanoscale circuits and memories where active devices are just a few nanometers square and wire pitches may be on the order of ten nanometers. The features can be defined at this scale without using photolithography. The available assembly techniques have relatively high defect rates compared to conventional lithographic integrated circuits and can only produce very regular structures. Nonetheless, with proper memory organization, it is reasonable to expect these technologies to provide memory densities in excess of 10/sup 11/ b/cm/sup 2/ with modest active power requirements under 0.6 W/Tb/s for random read operations.     

Three-dimensional structure of human protein kinase C interacting protein 1, a member of the HIT family of proteins

The three-dimensional structure of protein kinase C interacting protein 1 (PKCI-1) has been solved to high resolution by x-ray crystallography using single isomorphous replacement with anomalous scattering. The gene encoding human PKCI-1 was cloned from a cDNA library by using a partial sequence obtained from interactions identified in the yeast two-hybrid system between PKCI-1 and the regulatory domain of protein kinase C-beta. The PKCI-1 protein was expressed in Pichia pastoris as a dimer of two 13.7-kDa polypeptides. PKCI-1 is a member of the HIT family of proteins, shown by sequence identity to be conserved in a broad range of organisms including mycoplasma, plants, and humans. Despite the ubiquity of this protein sequence in nature, no distinct function has been shown for the protein product in vitro or in vivo. The PKCI-1 protomer has an alpha+beta meander fold containing a five-stranded antiparallel sheet and two helices. Two protomers come together to form a 10-stranded antiparallel sheet with extensive contacts between a helix and carboxy terminal amino acids of a protomer with the corresponding amino acids in the other protomer. PKCI-1 has been shown to interact specifically with zinc. The three-dimensional structure has been solved in the presence and absence of zinc and in two crystal forms. The structure of human PKCI-1 provides a model of this family of proteins which suggests a stable fold conserved throughout nature.     

Using time intervals between expected events to communicate risk magnitudes

Choledochal cyst is a rare pathology in western countries and the typical signs and symptoms are not always present at the onset. The diagnosis is often difficult and it needs a long time to be clear. In this paper we review our recent experience with this pathology (8 patients) and particularly we point out the problems of the delate in the diagnosis and the best choice to study these patients.