Global Competition, Institutions, And The Diffusion Of Organizational Practices: The International Spread Of Iso 9000 Quality Certificates

We use panel data on ISO 9000 quality certification in 85 countries between 1993 and 1998 to better understand, the cross-national diffusion of an organizational practice. Following neoinstitutional theory, we focus on the coercive, normative, and mimetic effects that result from the exposure of firms in a given country to a powerful source of critical resources, a common pool of relevant technical knowledge, and the experiences of firms located in other countries. We use social network theory to develop a systematic conceptual understanding of how firms located in different countries influence each other's rates of adoption as a result of cohesive and equivalent network relationships. Regression results provide support for our predictions that states and foreign multinationals are the key actors responsible for coercive isomorphism, cohesive trade relationships between countries generate coercive and normative effects, and role-equivalent trade relationships result in learning-based and competitive imitation.Business Administratio

The Origin and Significance of Reverse Zoning in Melilite from Allende Type B Inclusions

In many Type B Allende inclusions, melilite is reversely-zoned over restricted portions of each crystal. Textural relationships and the results of dynamic crystallization experiments suggest that the reverselyzoned intervals in these Type melilites result from the co-precipitation of melilite with clinopyroxene from a melt, prior to the onset of anorthite precipitation. When clinopyroxene begins to precipitate, the Al/Mg ratio of the melt rises, causing the crystallizing melilite to become more gehlenitic, an effect which is negated by crystallization of anorthite. Because the equilibrium crystallization sequence in these liquids is anorthite before pyroxene, melilite reverse zoning can occur only when anorthite nucleation is suppressed relative to pyroxene. This has been achieved in our experiments at cooling rates as low as 0.5°C/hour. Our experiments further indicate, however, that reverse zoning does not form at cooling rates ≥50°C/hour , probably because the clinopyroxene becomes too Al-rich to drive up the Al/Mg ratio of the liquid. Type inclusions with reversely-zoned melilites must have cooled at rates greater than those at which anorthite begins to crystallize before clinopyroxene but <50°C/hour. Such rates are far too slow for the Type droplets to have cooled by radiation into a nebular gas but are much faster than the cooling rate of the solar nebula itself. One possibility is that Type B's formed in local hot regions within the nebula, where their cooling rate was equal to that of their surrounding gas. Other possibilities are that their cooling rates reflect their movement along nebular temperature gradients or the influence of a heat source. The sun or viscous drag on inclusions as they moved through the nebular gas are potential candidates for such heat sources

ABO-incompatible Organs a Viable and Necessary Source for Transplants

Despite the astounding technological advancements of modern society, failure to receive a timely organ transplant accounts for the death of approximately 18 U.S. citizens each day. As the population continues to expand, so does the shortage of donor-recipient matching organs. In order to alleviate this deficit, medical researchers have addressed the most common barrier that accounts for donor-recipient denial: blood typing. Within recent years, immunological understanding has progressed leading researchers to believe ABO-incompatible organs may be a viable source for transplantation with unparalleled potential to expand donor availability. It is the intent of this review to increase public awareness of organ transplant issues, leading to, perhaps a global reorganization and revision of the organ transplantation system

Ecological resilience at semi-arid and temperate boundaries of the Mediterranean-type Fynbos Biome, South Africa, during the Holocene

Mediterranean-type ecosystems are amongst the most vulnerable to global change. Threats from desertification are projected due to rapid expansion of adjacent semiarid systems. Changes in fire frequency and intensity can alter ecosystem composition and structure, and potentially facilitate transitions between alternative stable states. Given the outstanding biodiversity of the Mediterranean-type fynbos biome in the Greater Cape Floristic Region (GCFR) of South Africa, understanding of the longterm impacts of global change are particularly important. In this study, palaeoecological data are used to assess the effects of changes in climate, fire and land use on vegetation at the semi-arid and temperate margins of the fynbos biome. Previous palaeoecological studies have shown stable fynbos during the recent geologic past, which restricts interpretation of the long-term ecological processes that determine biome resilience. This study sourced sediment cores directly from presentday fynbos-succulent karoo (semi-arid) and fynbos-afrotemperate forest biome boundaries to emphasise ecological dynamics. Fossil pollen, spores and charcoal were extracted from radiocarbon dated sediment cores to provide proxies for vegetation, hydrology, large herbivore abundance and fire. Constrained hierarchical clustering (CONISS), optimal sequence splitting by least-squares, and Non-metric Multidimensional Scaling (NMDS) was applied to the fossil data to identify distinct assemblages in the record, and to further elucidate ecosystem trajectories through time. At the semi-arid boundary at Groenkloof (5,500 cal yrs BP - near present), decreased moisture and fire from 4,000-735 cal yrs BP allowed colonisation of fynbos by a possible 'no-analogue' community dominated by Asteraceae and Poaceae. From 735 cal yrs BP however, climatic amelioration allowed fynbos to re-establish. The system can therefore be viewed as resilient through a capacity for 'recovery' and persistence through turnover in internal composition of fynbos taxa. This sensitive response to climatic forcing reflects the dominant influence of physiological stress at the semiarid limits of Mediterranean-type ecosystems, as well as a Gleasonian type community composition with loose species associations. In contrast, ecosyste

Probing Apoptotic Caspase Allostery and Exosite Interactions for Alternative Regulation

Programmed cell death, or apoptosis is a critical homeostatic pathway that monitors the balance of cell life and death. Apoptosis is regulated by a class of enzymes known as the cysteine aspartic proteases, or the caspases. The 12 human caspases that play important roles in the progression and regulation of apoptosis and inflammation. Caspases are tightly regulated by numerous factors including enzymatic activation, post-translational modifications, metal ligand binding, and protein modulation. Aberrant caspase activation and regulation has been implicated in the progression of numerous diseases such as proliferative diseases and neurodegeneration. The deeply entwined nature of caspases and apoptosis makes them interesting targets for therapeutic intervention of apoptotic diseases. However, the highly conserved fold and overlapping active site specificities makes the development of specific caspase modulators difficult. Therefore, it is critical to understand the mechanistic details of each caspases function, dynamics and specificity to further differentiate these homologous enzymes and uncover new scaffolds for select targeting of these enzymes. In this work, we aim to identify distal residues that comprise protein exosites which mediate the recruitment of proteins for enzymatic hydrolysis. First we developed an evolved specificity caspase that may be utilized for the identification of specific substrate that utilize exosite for caspase recognition and recruitment. Next we probed the details of caspase regulation by zinc validating the emerging signaling atom as an essential regulator of the caspases. Next we identified a putative exosite of caspase-6 located within the N-terminal domain that is essential for protein substrate recruitment and also modulates the dynamics of unique 130’s helix to strand interconversion of the enzyme. Lastly, we identified an active site adjacent inhibitor of caspase-6 that takes advantage of a unique evolutionarily conserved cysteine of caspase-6. Modulation of this distal cysteine serves as an anchor for the most selective, potent and cell permeable inhibitor of caspase-6 to date. The identification of exosites provides new scaffolds for development of specific inhibitors that take advantage of the unique characteristics of this family of enzymes. Interestingly, uncovering the details of protein exosites also provides the unique opportunity block substrate hydrolysis by targeting either the enzyme exosite or the substrate exosite, thereby expanding the chemical space for effective modulation and therapeutic intervention

A comparison of surface sensible and latent heat fluxes from aircraft and surface measurements in FIFE 1987

Surface fluxes of sensible and latent heat over a tall-grass prairie in central Kansas, as measured by 22 surface stations during FIFE 1987, are compared with values gained indirectly by linear extrapolation of aircraft-measured flux profiles to the surface. The results of 33 such comparisons covering the period 26 June to 13 October 1987 indicate that the sensible heat flux profiles were generally more linear with less scatter in the measurements at each level than were the latent heat flux profiles, the profile extrapolations of sensible heat flux in general underestimate the surface averages by about 30 percent, with slightly better agreement during periods of small flux, and the profile extrapolations of latent heat flux in general underestimate the surface averages by about 15 percent, with overestimates during periods of small fluxes (dry conditions) and overestimates during periods of large fluxes (moist conditions). Possible origins of the differences between the two sets of measurements are discussed, as directions for further research

A study of amylolytic streptococci from the rumen of the sheep

Ruminants comprise a large class of mammals distributed over the greater part of the earth's surface. The digestive system of these animals has been adapted for the digestion of grass and other cellulosic materials which form the natural diet of the group as a whole. Since this diet is both bulky and indigestible it is to be expected that the ratio of the capacity of the digestive system to body weight is higher in ruminants than it is for example in carnivorous animals. For this purpose the lower part of the oesophagus in the ruminant forms a large sac or rumen. The ingested food passes into the rumen and is mixed with the dense rumen microbial population. It is in the rumen that the digestion of cellulose by rumen bacteria takes place. The relationship between the rumen microflora and the host is thought to be symbiotic and since a large percentage of the world's human population is dependent directly or indirectly upon ruminants for food the economic importance of this symbiotic relationship cannot be over emphasised. Especially asp but for these animals much of the yearly crop of grass and other cellulosic material would not be converted into protein but broken down by soil bacteria and so be lost to man.In most parts of the world the continuous growth of plants is not possible, due to the sequence of the seasons or to the alternation of wet and dry periods. Thus, at intervals, herbivores must live on vegetation which has completed its growth cycle and has become dry, woody and resistant to digestion. The digestive system of the ruminant can utilise such material and as a result these animals are not seriously affected by drought and other inclement weather conditions. This may account for the success of the group in the modern world. In addition it is this ability to utilise cellulose efficiently that has led to the domestication and breeding of the ruminant

Interaction of Supernova Ejecta with Nearby Protoplanetary Disks

The early Solar System contained short-lived radionuclides such as 60Fe (t1/2 = 1.5 Myr) whose most likely source was a nearby supernova. Previous models of Solar System formation considered a supernova shock that triggered the collapse of the Sun's nascent molecular cloud. We advocate an alternative hypothesis, that the Solar System's protoplanetary disk had already formed when a very close (< 1 pc) supernova injected radioactive material directly into the disk. We conduct the first numerical simulations designed to answer two questions related to this hypothesis: will the disk be destroyed by such a close supernova; and will any of the ejecta be mixed into the disk? Our simulations demonstrate that the disk does not absorb enough momentum from the shock to escape the protostar to which it is bound. Only low amounts (< 1%) of mass loss occur, due to stripping by Kelvin-Helmholtz instabilities across the top of the disk, which also mix into the disk about 1% of the intercepted ejecta. These low efficiencies of destruction and injectation are due to the fact that the high disk pressures prevent the ejecta from penetrating far into the disk before stalling. Injection of gas-phase ejecta is too inefficient to be consistent with the abundances of radionuclides inferred from meteorites. On the other hand, the radionuclides found in meteorites would have condensed into dust grains in the supernova ejecta, and we argue that such grains will be injected directly into the disk with nearly 100% efficiency. The meteoritic abundances of the short-lived radionuclides such as 60Fe therefore are consistent with injection of grains condensed from the ejecta of a nearby (< 1 pc) supernova, into an already-formed protoplanetary disk.Comment: 57 pages, 16 figure