Showing papers by "University of New Mexico published in 1999"
TL;DR: This work discloses that expression of Hsps can occur in nature, all species have hsp genes but they vary in the patterns of their expression, and Hsp expression can be correlated with resistance to stress, and species' thresholds for HSP expression are correlated with levels of stress that they naturally undergo.
Abstract: Molecular chaperones, including the heat-shock proteins (Hsps), are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the most attention in model organisms undergoing experimental stress in the laboratory, and the function of Hsps at the molecular and cellular level is becoming well understood in this context. A complementary focus is now emerging on the Hsps of both model and nonmodel organisms undergoing stress in nature, on the roles of Hsps in the stress physiology of whole multicellular eukaryotes and the tissues and organs they comprise, and on the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This focus discloses that (a) expression of Hsps can occur in nature, (b) all species have hsp genes but they vary in the patterns of their expression, (c) Hsp expression can be correlated with resistance to stress, and (d) species' thresholds for Hsp expression are correlated with levels of stress that they naturally undergo. These conclusions are now well established and may require little additional confirmation; many significant questions remain unanswered concerning both the mechanisms of Hsp-mediated stress tolerance at the organismal level and the evolutionary mechanisms that have diversified the hsp genes.
3,841 citations
TL;DR: Gemfibrozil therapy resulted in a significant reduction in the risk of major cardiovascular events in patients with coronary disease whose primary lipid abnormality was a low HDL cholesterol level, suggesting that the rate of coronary events is reduced by raising HDL cholesterol levels and lowering levels of triglycerides without lowering LDL cholesterol levels.
Abstract: Background Although it is generally accepted that lowering elevated serum levels of low-density lipoprotein (LDL) cholesterol in patients with coronary heart disease is beneficial, there are few data to guide decisions about therapy for patients whose primary lipid abnormality is a low level of high-density lipoprotein (HDL) cholesterol. Methods We conducted a double-blind trial comparing gemfibrozil (1200 mg per day) with placebo in 2531 men with coronary heart disease, an HDL cholesterol level of 40 mg per deciliter (1.0 mmol per liter) or less, and an LDL cholesterol level of 140 mg per deciliter (3.6 mmol per liter) or less. The primary study outcome was nonfatal myocardial infarction or death from coronary causes. Results The median follow-up was 5.1 years. At one year, the mean HDL cholesterol level was 6 percent higher, the mean triglyceride level was 31 percent lower, and the mean total cholesterol level was 4 percent lower in the gemfibrozil group than in the placebo group. LDL cholesterol levels...
3,327 citations
TL;DR: The incidence of hepatocellular carcinoma increased significantly among younger persons (40 to 60 years old) during the period from 1991 to 1995 as compared with earlier periods, and the age-specific incidence of this cancer has progressively shifted toward younger people.
Abstract: Background and Methods Clinical observations have suggested that the number of cases of hepatocellular carcinoma has increased in the United States. We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) data base to determine the age-adjusted incidence of hepatocellular carcinoma from 1976 to 1995, data from the U.S. vital-statistics data base to determine age-adjusted mortality rates from 1981 to 1995, and data from the Department of Veterans Affairs to determine age-adjusted rates of hospitalization for the disease from 1983 to 1997. Results The incidence of histologically proved hepatocellular carcinoma increased from 1.4 per 100,000 population (95 percent confidence interval, 1.3 to 1.4) for the period from 1976 to 1980 to 2.4 per 100,000 (95 percent confidence interval, 2.3 to 2.4) for the period from 1991 to 1995. Among black men, the incidence was 6.1 per 100,000 for the period from 1991 to 1995, and among white men, it was 2.8 per 100,000. There was a 41 percent increase in ...
2,869 citations
TL;DR: In this paper, a simple evaporation-induced self-assembly (EISA) process is proposed for the rapid production of patterned porous or nanocomposite materials in the form of films, fibers, or powders.
Abstract: As we look toward the next millennium, we envision new technologies based on nanoscale machines and devices. Key to the realization of this nanotech world are simple, efficient methods of organizing materials (molecules, molecular clusters, polymers, or, generally speaking, building blocks) into precise, predetermined nanostructures that can be preserved in a robust engineering form. Marine organisms like diatoms and radiolaria provide us with many examples of intricately organized architectures preserved in silica or calcium carbonate. Such natural microstructures are formed by biomineralization, a templated self-assembly process in which preorganized organic surfaces regulate the nucleation, growth, morphology and orientation of inorganic crystals. To date, a variety of synthetic pathways that mimic aspects of biomineralization have been explored to prepare patterned ceramic materials. In an early attempt to achieve antigen/ antibodyselectivity inaporousadsorbent,Dickey prepared silicagels inthepresenceofthetargetmoleculetobeadsorbed (in this case methyl orange). After methyl orange extraction, the resulting templated silicas showed preferential selectivity for methyl orange over its alkyl orange homologues. In the 1960s researchers at the Mobil Oil Corporation used alkylammonium ions as templates to control the pore size, shape and periodicity of zeolites, crystalline solids that define 1-, 2-, or 3-dimensional (1-, 2-, or 3-D, respectively) networks of microporous channels. More recently Kresge and colleagues at Mobil used longer-chain alkylammonium ions in an attempt to increase the maximum pore size of zeolites beyond ~1.2 nm. They observed honeycomb-like arrays of ~4 nm pores and, based on analogies with hexagonal liquidcrystalline systems, proposed a supramolecular liquid-crystalline templating mechanism. Although excellent progress has been made in the preparationofawidevarietyofpatternedceramicmaterials, current synthetic methods have several inherent drawbacks fromthestandpointofnanotechnology:First,mosttemplating procedures are conducted in time-consuming batch operations often employing hydrothermal processing conditions. Second, the resultant products are typically ill-defined powders, precluding their general use in thin film technologies. Third, procedures developed to date are often limited to forming patterns of pores. For many envisioned nanotechnologies, it would be desirable to create patterned nanocomposites consisting of periodic arrangements of two or more dissimilar materials. This article summarizes a simple evaporation-induced self-assembly (EISA) process, that enables the rapid production of patterned porous or nanocomposite materials in the form of films, fibers, or powders.
1,974 citations
TL;DR: The Mini Nutritional Assessment has recently been designed and validated to provide a single, rapid assessment of nutritional status in elderly patients in outpatient clinics, hospitals, and nursing homes and was found to be predictive of mortality and hospital cost.
1,540 citations
TL;DR: Fractal-like networks effectively endow life with an additional fourth spatial dimension, and design principles are independent of detailed dynamics and explicit models and should apply to virtually all organisms.
Abstract: Fractal-like networks effectively endow life with an additional fourth spatial dimension. This is the origin of quarter-power scaling that is so pervasive in biology. Organisms have evolved hierarchical branching networks that terminate in size-invariant units, such as capillaries, leaves, mitochondria, and oxidase molecules. Natural selection has tended to maximize both metabolic capacity, by maximizing the scaling of exchange surface areas, and internal efficiency, by minimizing the scaling of transport distances and times. These design principles are independent of detailed dynamics and explicit models and should apply to virtually all organisms.
1,528 citations
TL;DR: Reviews of the literature concerning deserts, boreal forests, tropical forests, lakes, and wetlands lead to the conclusion that extant data are insufficient to conclusively resolve the relationship between diversity and productivity, or that patterns are variable with mechanisms equally varied and complex.
Abstract: ▪ Abstract Recent overviews have suggested that the relationship between species richness and productivity (rate of conversion of resources to biomass per unit area per unit time) is unimodal (hump-shaped). Most agree that productivity affects species richness at large scales, but unanimity is less regarding underlying mechanisms. Recent studies have examined the possibility that variation in species richness within communities may influence productivity, leading to an exploration of the relative effect of alterations in species number per se as contrasted to the addition of productive species. Reviews of the literature concerning deserts, boreal forests, tropical forests, lakes, and wetlands lead to the conclusion that extant data are insufficient to conclusively resolve the relationship between diversity and productivity, or that patterns are variable with mechanisms equally varied and complex. A more comprehensive survey of the ecological literature uncovered approximately 200 relationships, of which 3...
1,283 citations
TL;DR: In this paper, an integrated model for the hydrodynamics, biomechanics and branching geometry of plants, based on the application of a general theory of resource distribution through hierarchical branching networks, is presented.
Abstract: Vascular plants vary in size by about twelve orders of magnitude, and a single individual sequoia spans nearly this entire range as it grows from a seedling to a mature tree. Size influences nearly all of the structural, functional and ecological characteristics of organisms1,2. Here we present an integrated model for the hydrodynamics, biomechanics and branching geometry of plants, based on the application of a general theory of resource distribution through hierarchical branching networks3 to the case of vascular plants. The model successfully predicts a fractal-like architecture and many known scaling laws, both between and within individual plants, including allometric exponents which are simple multiples of 1/4. We show that conducting tubes must taper and, consequently, that the resistance and fluid flow per tube are independent of the total path length and plant size. This resolves the problem of resistance increasing with length, thereby allowing plants to evolve vertical architectures and explaining why the maximum height of trees is about 100 m. It also explains why the energy use of plants in ecosystems is size independent.
1,253 citations
01 Jan 1999
TL;DR: This work compares the ability of different data modeling methods to represent normal behavior accurately and to recognize intrusions and concludes that for this particular problem, weaker methods than HMMs are likely sufficient.
Abstract: Intrusion detection systems rely on a wide variety of observable data to distinguish between legitimate and illegitimate activities. We study one such observable-sequences of system calls into the kernel of an operating system. Using system-call data sets generated by several different programs, we compare the ability of different data modeling methods to represent normal behavior accurately and to recognize intrusions. We compare the following methods: simple enumeration of observed sequences; comparison of relative frequencies of different sequences; a rule induction technique; and hidden Markov models (HMMs). We discuss the factors affecting the performance of each method and conclude that for this particular problem, weaker methods than HMMs are likely sufficient.
1,245 citations
TL;DR: In this article, the authors present new results based on the entire CHOOZ (The CHooZ experiment is named after the new nuclear power station operated by Electricite de France (EdF) near the village of Chooz in the Ardennes region of France) data sample.
1,146 citations
Brigham and Women's Hospital1, Brown University2, University of Pennsylvania3, Leicester Royal Infirmary4, St Vincent Hospital5, Université de Montréal6, University of Michigan7, University of New Mexico8, Dartmouth College9, University of Virginia10, Harvard University11, Roosevelt Institute12, Howard Hughes Medical Institute13
TL;DR: The findings support a model for FPD/AML in which haploinsufficiency of CBFA2 causes an autosomal dominant congenital platelet defect and predisposes to the acquisition of additional mutations that cause leukaemia.
Abstract: Familial platelet disorder with predisposition to acute myelogenous leukaemia (FPD/AML, MIM 601399) is an autosomal dominant disorder characterized by qualitative and quantitative platelet defects, and propensity to develop acute myelogenous leukaemia (AML). Informative recombination events in 6 FPD/AML pedigrees with evidence of linkage to markers on chromosome 21q identified an 880-kb interval containing the disease gene. Mutational analysis of regional candidate genes showed nonsense mutations or intragenic deletion of one allele of the haematopoietic transcription factor CBFA2 (formerly AML1) that co-segregated with the disease in four FPD/AML pedigrees. We identified heterozygous CBFA2 missense mutations that co-segregated with the disease in the remaining two FPD/AML pedigrees at phylogenetically conserved amino acids R166 and R201, respectively. Analysis of bone marrow or peripheral blood cells from affected FPD/AML individuals showed a decrement in megakaryocyte colony formation, demonstrating that CBFA2 dosage affects megakaryopoiesis. Our findings support a model for FPD/AML in which haploinsufficiency of CBFA2 causes an autosomal dominant congenital platelet defect and predisposes to the acquisition of additional mutations that cause leukaemia.
TL;DR: In this article, the authors report a rapid, aerosol process that results in solid, completely ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures, which relies on evaporation-induced interfacial self-assembly confined to a spherical aerosol droplet.
Abstract: Nanostructured particles exhibiting well-defined pore sizes and pore connectivities (1-, 2-, or 3-dimensional) are of interest for catalysis, chromatography, controlled release, low dielectric constant fillers, and custom-designed pigments and optical hosts During the last several years considerable progress has been made on controlling the macroscopic forms of mesoporous silicas prepared by surfactant and block copolymer liquid crystalline templating procedures Typically interfacial phenomena are used to control the macroscopic form (particles, fibers, or films), while self-assembly of amphiphilic surfactants or polymers is used to control the mesostructure To date, although a variety of spherical or nearly-spherical particles have been prepared, their extent of order is limited as is the range of attainable mesostructures They report a rapid, aerosol process that results in solid, completely ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures The process relies on evaporation-induced interfacial self-assembly (EISA) confined to a spherical aerosol droplet The process is simple and generalizable to a variety of materials combinations Additionally, it can be modified to provide the first aerosol route to the formation of ordered mesostructured films
TL;DR: An overview of different physicochemical instrumental techniques for direct and indirect identification of bacteria such as: infrared and fluorescence spectroscopy, flow cytometry, chromatography and chemiluminescence techniques as a basis for biosensor construction is presented.
TL;DR: This work demonstrated that the fluorescence of Escherichia coli cells expressing GFP fusions is related to the productive folding of the upstream protein domains expressed alone, providing a simple route to improving protein folding and expression by directed evolution.
Abstract: Formation of the chromophore of green fluorescent protein (GFP) depends on the correct folding of the protein. We constructed a "folding reporter" vector, in which a test protein is expressed as an N-terminal fusion with GFP. Using a test panel of 20 proteins, we demonstrated that the fluorescence of Escherichia coli cells expressing such GFP fusions is related to the productive folding of the upstream protein domains expressed alone. We used this fluorescent indicator of protein folding to evolve proteins that are normally prone to aggregation during expression in E. coli into closely related proteins that fold robustly and are fully soluble and functional. This approach to improving protein folding does not require functional assays for the protein of interest and provides a simple route to improving protein folding and expression by directed evolution.
Yale University1, George Washington University2, Indiana University – Purdue University Indianapolis3, Case Western Reserve University4, University of Cincinnati5, National Institutes of Health6, University of Texas Southwestern Medical Center7, Wayne State University8, University of Miami9, University of Tennessee Health Science Center10, Emory University11, Stanford University12, University of New Mexico13
TL;DR: Appropriate-for-gestational age infants who survived to hospital discharge without developing chronic lung disease, severe intraventricular hemorrhage, necrotizing enterocolitis, or late onset-sepsis gained weight faster than comparable infants with those morbidities.
Abstract: Background. The interpretation of growth rates for very low birth weight infants is obscured by limited data, recent changes in perinatal care, and the uncertain effects of multiple therapies. Objectives. To develop contemporary postnatal growth curves for very low birth weight preterm infants and to relate growth velocity to birth weight, nutritional practices, fetal growth status (small- or appropriate-for-gestational-age), and major neonatal morbidities (chronic lung disease, nosocomial infection or late-onset infection, severe intraventricular hemorrhage, and necrotizing enterocolitis). Design. Large, multicenter, prospective cohort study. Methods. Growth was prospectively assessed for 1660 infants with birth weights between 501 to 1500 g admitted by 24 hours of age to 1 of the 12 National Institute of Child Health and Human Development Neonatal Research Network centers between August 31, 1994 and August 9, 1995. Infants were included if they survived >7 days (168 hours) and were free of major congenital anomalies. Anthropometric measures (body weight, length, head circumference, and midarm circumference) were performed from birth until discharge, transfer, death, age 120 days, or a body weight of 2000 g. To obtain representative data, nutritional practices were not altered by the study protocol. Results. Postnatal growth curves suitable for clinical and research use were constructed for body weight, length, head circumference, and midarm circumference. Once birth weight was regained, weight gain (14.4–16.1 g/kg/d) approximated intrauterine rates. However, at hospital discharge, most infants born between 24 and 29 weeks of gestation had not achieved the median birth weight of the reference fetus at the same postmenstrual age. Gestational age, race, and gender had no effect on growth within 100-g birth weight strata. Appropriate-for-gestational age infants who survived to hospital discharge without developing chronic lung disease, severe intraventricular hemorrhage, necrotizing enterocolitis, or late onset-sepsis gained weight faster than comparable infants with those morbidities. More rapid weight gain was also associated with a shorter duration of parenteral nutrition providing at least 75% of the total daily fluid volume, an earlier age at the initiation of enteral feedings, and an earlier age at achievement of full enteral feedings. Conclusions. These growth curves may be used to better understand postnatal growth, to help identify infants developing illnesses affecting growth, and to aid in the design of future research. They should not be taken as optimal. Randomized clinical trials should be performed to evaluate whether different nutritional management practices will permit birth weight to be regained earlier and result in more rapid growth, more appropriate body composition, and improved short- and long-term outcomes.
TL;DR: Age-related loss of muscle mass and strength occurs in relatively healthy, well-nourished elderly men and women and has a multifactorial basis.
TL;DR: In this article, Johnson/Cousins B, V, R, and I photometric observations of 22 recent Type Ia supernovae (SNe Ia): SNe 1993ac, 1993ae, 1994M, 1994S, 1994T, 1994Q, 1994ae, 1995D, 1995E, 1995al, 1995ac, 1995ak, 1995bd, 1996C, 1996X, 1996Z, 1996ab, 1996ai, 1996bk, 1996bl, 1996bo, and 1996bv.
Abstract: We present 1210 Johnson/Cousins B, V, R, and I photometric observations of 22 recent Type Ia supernovae (SNe Ia): SNe 1993ac, 1993ae, 1994M, 1994S, 1994T, 1994Q, 1994ae, 1995D, 1995E, 1995al, 1995ac, 1995ak, 1995bd, 1996C, 1996X, 1996Z, 1996ab, 1996ai, 1996bk, 1996bl, 1996bo, and 1996bv. Most of the photometry was obtained at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics in a cooperative observing plan aimed at improving the database for SNe Ia. The redshifts of the sample range from cz = 1200 to 37,000 km s-1 with a mean of cz = 7000 km s-1.
TL;DR: Findings fail to support the dichotomy in calcium signaling modes that had previously been proposed for protostomes vs deuterostomes and instead suggest that various features of fertilization-induced calcium signals are widely shared throughout the animal kingdom.
TL;DR: Mutations in human NKX2.5 cause a variety of cardiac anomalies and may account for a clinically significant portion of tetralogy of Fallot and idiopathic AV block.
Abstract: Heterozygous mutations in NKX2.5, a homeobox transcription factor, were reported to cause secundum atrial septal defects and result in atrioventricular (AV) conduction block during postnatal life. To further characterize the role of NKX2.5 in cardiac morphogenesis, we sought additional mutations in groups of probands with cardiac anomalies and first-degree AV block, idiopathic AV block, or tetralogy of Fallot. We identified 7 novel mutations by sequence analysis of the NKX2.5-coding region in 26 individuals. Associated phenotypes included AV block, which was the primary manifestation of cardiac disease in nearly a quarter of affected individuals, as well as atrial septal defect and ventricular septal defect. Ventricular septal defect was associated with tetralogy of Fallot or double-outlet right ventricle in 3 individuals. Ebstein’s anomaly and other tricuspid valve abnormalities were also present. Mutations in human NKX2.5 cause a variety of cardiac anomalies and may account for a clinically significant portion of tetralogy of Fallot and idiopathic AV block. The coinheritance of NKX2.5 mutations with various congenital heart defects suggests that this transcription factor contributes to diverse cardiac developmental pathways.
J. Clin. Invest. 104:1567–1573 (1999).
TL;DR: In this paper, a theoretical framework for relating life-history variables to rates of production, dM/dt, where M is above-ground mass and t is time, was provided.
Abstract: A prominent feature of comparative life histories is the well documented negative correlation between growth rate and life span1,2. Patterns of resource allocation during growth and reproduction reflect life-history differences between species1,2. This is particularly striking in tropical forests, where tree species can differ greatly in their rates of growth and ages of maturity but still attain similar canopy sizes3,4. Here we provide a theoretical framework for relating life-history variables to rates of production, dM/dt, where M is above-ground mass and t is time. As metabolic rate limits production as an individual grows, dM/dt ∝ M3/4. Incorporating interspecific variation in resource allocation to wood density, we derive a universal growth law that quantitatively fits data for a large sample of tropical tree species with diverse life histories. Combined with evolutionary life-history theory1, the growth law also predicts several qualitative features of tree demography and reproduction. This framework also provides a general quantitative answer to why relative growth rate (1/M)(dM/df) decreases with increasing plant size (∝M-1/4) and how it varies with differing allocation strategies5,6,7,8.
TL;DR: MDR1 is less frequent in younger AML patients, which may in part explain their better response to therapy and neither MRP1 nor LRP are significant predictors of outcome in this patient group, so inclusion of MDR1-modulators alone may benefit younger AMl patients with MDR 1(+) disease.
TL;DR: The authors argue that the insider status of the researcher, the centrality of action, the requirement of spiraling self-reflection on action, and the intimate, dialectical relationship of research to practice make practitioner research alien to researchers who work out of Gage's three academic paradigms.
Abstract: ccording to Schon (1995) "the new scholarship" implies "a kind of action research with norms of its own, which will conflict with the norms of technical rationality-the prevailing epistemology built into the research universities" (p. 27). The "battle" of snails that Schon refers to echoes the "paradigm wars" among "positivists," interpretivists, and critical theorists, satirically described by Gage (1989) in the pages of Educational Researcher. While we believe that practitioner research cannot be subsumed under any of Gage's three paradigms without doing it damage, our purpose in this article is not to argue for separate paradigm status. Nevertheless, we believe that the insider status of the researcher, the centrality of action, the requirement of spiraling self-reflection on action, and the intimate, dialectical relationship of research to practice, all make practitioner research alien (and often suspect) to researchers who work out of Gage's three academic paradigms. If anything, academic traditions of feminist and poststructural research might be more compatible with these characteristics. It is interesting to speculate on why metaphors of war and battles are evoked to discuss these epistemological debates. While it could be attributed to the academic version
TL;DR: In this paper, neutral atoms are trapped in a very far-off-resonance optical lattice, and pairs of atoms are made to occupy the same well by varying the polarization of the trapping lasers.
Abstract: We propose a new system for implementing quantum logic gates: neutral atoms trapped in a very far-off-resonance optical lattice. Pairs of atoms are made to occupy the same well by varying the polarization of the trapping lasers, and then a near-resonant electric dipole is induced by an auxiliary laser. A controlled-NOT can be implemented by conditioning the target atomic resonance on a resolvable level shift induced by the control atom. Atoms interact only during logical operations, thereby suppressing decoherence.
TL;DR: Though this result raises questions about NMR quantum computation, further analysis would be necessary to assess the power of the general unitary transformations, which are indeed implemented in these experiments, in their action on separable states.
Abstract: We give a constructive proof that all mixed states of N qubits in a sufficiently small neighborhood of the maximally mixed state are separable (unentangled). The construction provides an explicit representation of any such state as a mixture of product states. We give upper and lower bounds on the size of the neighborhood, which show that its extent decreases exponentially with the number of qubits. The bounds show that no entanglement appears in the physical states at any stage of present NMR experiments. Though this result raises questions about NMR quantum computation, further analysis would be necessary to assess the power of the general unitary transformations, which are indeed implemented in these experiments, in their action on separable states.
TL;DR: Using photographs of men's faces, a relationship between women's attractiveness ratings of these faces and symmetry is found, but the subjects could not rate facial symmetry accurately, suggesting that attractive features other than symmetry can be used to assess phenotypic condition.
Abstract: Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.
TL;DR: In this article, three different theoretical explanations are tested for the exceptionally high level of electoral volatility found in contemporary Latin America: economic voting, institutional characteristics of political regimes and party systems, and the structure and organization of class cleavages.
Abstract: Three different theoretical explanations are tested for the exceptionally high level of electoral volatility found in contemporary Latin America: economic voting, institutional characteristics of political regimes and party systems, and the structure and organization of class cleavages. A pooled cross-sectional time-series regression analysis is conducted on 58 congressional elections and 43 presidential elections in 16 Latin American countries during the 1980s and 1990s. Institutional variables have the most consistent effect on volatility, while the influence of economic performance is heavily contingent upon the type of election and whether the dependent variable is operationalized as incumbent vote change or aggregate electoral volatility. The results demonstrate that electoral volatility is a function of short-term economic perturbations, the institutional fragilities of both democratic regimes and party systems, and relatively fluid cleavage structures.
01 May 1999
TL;DR: This paper introduces a model for supporting collaborative work between people that are physically close to each other, and describes themodel, comparing it to more traditional remote collaboration and describing the requirements that SDG places on computer technology.
Abstract: We introduce a model for supporting collaborative work between people that are physically close to each other. We call this model Single Display Groupware (SDG). In this paper, we describe the model, comparing it to more traditional remote collaboration, We describe the requirements that SDG places on computer technology, and our understanding of the benefits and costs of SDG systems. Finally, we describe a prototype SDG system that we built and the results of a usability test we ran with 60 elementary school children.
TL;DR: In this paper, the authors combine energetic and demographic approaches in order to examine the human life course from an optimality perspective, which solves related problems across two generations by solving the problems of trade-offs between current and future reproduction and quality versus quantity of offspring.
Abstract: ▪ Abstract Life history theory offers evolutionary explanations for the timing of life events, with a particular focus on age-schedules of fertility and mortality and growth. Traditional models examine trade-offs between current and future reproduction and quality versus quantity of offspring. These models can be used to understand questions concerning time of gestation, age of weaning, juvenile mortality profiles, age at maturation, adult body size, fertility rates, senescence, menopause, and the length of the life span. The trajectory of energy acquisition and its allocations is also an important part of life history theory. Modifications of these models have been developed to examine the period of learning, postweaning parental investment, and patterns of development. In this article, we combine energetic and demographic approaches in order to examine the human life course from an optimality perspective. The evolved life history solves related problems across two generations. The first set of decisions...
TL;DR: In this paper, the lowest room-temperature threshold current density, 26 A/cm/sup 2 ), of any semiconductor diode laser was reported for a quantum dot device with a single InAs dot layer contained within a strained In/sub 0.85/As quantum well.
Abstract: The lowest room-temperature threshold current density, 26 A/cm/sup 2/, of any semiconductor diode lasers is reported for a quantum dot device with a single InAs dot layer contained within a strained In/sub 0.15/Ga/sub 0.85/As quantum well. The lasers are epitaxially grown on a GaAs substrate, and the emission wavelength is 1.25 /spl mu/m.