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Showing papers by "University of New Mexico published in 1995"


Journal ArticleDOI
TL;DR: In this article, a universal constitutive equation between the heat flux vector and the temperature gradient is proposed to cover the fundamental behaviors of diffusion, wave, phonon-electron interactions, and pure phonon scattering.
Abstract: A universal constitutive equation between the heat flux vector and the temperature gradient is proposed to cover the fundamental behaviors of diffusion (macroscopic in both space and time), wave (macroscopic in space but microscopic in time), phonon-electron interactions (microscopic in both space and time), and pure phonon scattering The model is generalized from the dual-phase-lag concept accounting for the laging behavior in the high-rate response While the phase lag of the heat flux captures the small-scale response in time, the phase lag of the temperature gradient captures the small-scale response in space The universal form of the energy equation facilitates identifications of the physical parameters governing the transition from one mechanism (such as diffusion or wave) to another (the phonon-electron interaction)

1,435 citations


Journal ArticleDOI
TL;DR: This article seeks to define motivational interviewing and to characterize its essential nature, differentiating it from other approaches with which it may be confused.
Abstract: Motivational interviewing is a directive, client-centred counselling style for eliciting behaviour change by helping clients to explore and resolve ambivalence. It is most centrally defined not by technique but by its spirit as a facilitative style for interpersonal relationship. This article seeks to define motivational interviewing and to characterize its essential nature, differentiating it from other approaches with which it may be confused. A brief update is also provided regarding (1) evidence for its efficacy and (2) new problem areas and populations to which it is being applied.

1,359 citations


Journal Article
TL;DR: In this article, the authors examined whether social presence is largely an attribute of the communication medium or users' perception of the medium and concluded that the kind of interactions that take place between the participants, and the sense of community that is created during the conference, that will impact participants' perceptions of CMC as a social medium.
Abstract: This paper examines research on social presence theory and the implications for analyzing interaction, communication, collaborative learning, and the social context of computermediated communication (CMC). Two studies that examined whether social presence is largely an attribute of the communication medium or users’ perception of the medium are discussed. It can be concluded from the results that even though CMC is considered to be a medium that is low in social context cues, it can be perceived as interactive, active, interesting, and stimulating by conference participants. However, it is the kind of interactions that take place between the participants, and the sense of community that is created during the conference, that will impact participants’ perceptions of CMC as a “social” medium. Therefore, the impetus falls upon the moderators of computer conferences to create a sense of online community in order to promote interaction and collaborative learning.

1,131 citations


Journal ArticleDOI
Fumio Abe, H. Akimoto1, A. Akopian2, M. G. Albrow3  +443 moreInstitutions (34)
TL;DR: In this paper, the existence of the top quark was established using a data sample of collisions at the Fermilab National Ensemble (CDF) collected with the Collider Detector.
Abstract: We establish the existence of the top quark using a $67{\mathrm{pb}}^{\ensuremath{-}1}$ data sample of $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with $t\overline{t}$ decay to $\mathrm{WWb}\overline{b}$, but inconsistent with the background prediction by $4.8\ensuremath{\sigma}$. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be $176\ifmmode\pm\else\textpm\fi{}8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}10(\mathrm{syst})\mathrm{GeV}{/c}^{2}$, and the $t\overline{t}$ production cross section to be ${6.8}_{\ensuremath{-}2.4}^{+3.6}\mathrm{pb}$.

1,022 citations


Journal ArticleDOI
TL;DR: The interaction of phonological properties of lexical patterns with frequency and the interaction of type and token frequency are shown to influence degree of productivity in three models of morphological storage and processing.
Abstract: Three models of morphological storage and processing are compared: the dual-processing model of Pinker, Marcus and colleagues, the connectionist model of Marchman, Plunkett, Seidenberg and others, and the network model of Bybee and Langacker. In line with predictions made in the latter two frameworks, type frequency of a morphological pattern is shown to be important in determining productivity. In addition, the paper considers the nature of lexical schemas in the network model, which are of two types: source-oriented and product-oriented. The interaction of phonological properties of lexical patterns with frequency and the interaction of type and token frequency are shown to influence degree of productivity. Data are drawn from English, German, Arabic and Hausa.

1,010 citations


Journal ArticleDOI
TL;DR: In this article, an extension to solid mechanics of the FLIP particle-in-cell method is presented, which uses two representations of the continuum, one based on a collection of material points and the other based on computational grid.

781 citations


Journal ArticleDOI
22 Mar 1995-JAMA
TL;DR: There was no decrease in mortality between placebo and TNF-α MAb in all infused patients, and in septic shock patients who received T NF- α MAb, a significant reduction in mortality was present 3 days after infusion; however, although a trend toward reduced mortality continued at 28 days following treatment with TTFMAb, the difference in mortality among shock patients treated with placebo or TFB was not significant.
Abstract: Objective. —To evaluate the efficacy and safety of anti—tumor necrosis factor α monoclonal antibody (TNF-α MAb) in the treatment of patients with sepsis syndrome. Design. —Randomized, prospective, multicenter, double-blind, placebo-controlled clinical trial. Setting. —A total of 31 hospitals in the United States and Canada. Patients. —There were 994 patients with sepsis syndrome enrolled in this clinical trial, and 971 patients were infused with the study drug. Intervention. —Patients were prospectively stratified into shock or nonshock groups and then randomized to receive a single infusion of 15 mg/kg of TNF-α MAb, 7.5 mg/kg of TNF-α MAb, or placebo. Patients received standard aggressive medical and surgical care during the 28-day postinfusion period. Outcome Measure. —Twenty-eight-day all-cause mortality. Results. —The distribution of variables describing demographics, organ system dysfunction or failure, preinfusion Acute Physiology and Chronic Health Evaluation II score, number of organs failing at baseline, initial sites of infection, infecting microorganisms, antimicrobials used, and initial invasive procedures was similar among patients in the TNF-α MAb and placebo treatment arms. Among all infused patients, there was no difference in all-cause mortality in patients who received placebo as compared with those who received TNF-α MAb. In septic patients with shock (n=478), there was a trend toward a reduction in all-cause mortality, which was most evident 3 days after infusion: 25 of 162 patients treated with 15 mg/kg of TNF-α MAb died, 22 of 156 patients treated with 7.5 mg/kg of TNF-α MAb died, and 44 of 160 patients in the placebo group died (15 mg/kg: 44% reduction vs placebo, P =.01; 7.5 mg/kg: 48.7% reduction vs placebo, P =.004). At day 28, the reduction in mortality for shock patients was not significant for either dose of TNF-α MAb relative to placebo (15 mg/kg, 61 deaths among 162 patients [37.7% mortality]; 7.5 mg/kg, 59 deaths among 156 patients [37.8% mortality]; placebo, 73 deaths among 160 patients [45.6% mortality]; P =.20 for 7.5 mg/kg and P =.15 for 15 mg/kg). Serious adverse events were reported in 4.6% of all infused patients. No immediate hypersensitivity allergic reactions due to TNF-α MAb were reported. Serum sickness—like reactions were seen in 2.5% of patients receiving TNF-α MAb. Conclusions. —There was no decrease in mortality between placebo and TNF-α MAb in all infused patients. In septic shock patients who received TNF-α MAb, a significant reduction in mortality was present 3 days after infusion. Although a trend toward reduced mortality continued at 28 days following treatment with TNF-α MAb, the difference in mortality among shock patients treated with placebo or TNF-α MAb was not significant. ( JAMA . 1995;273:934-941)

757 citations


Journal ArticleDOI
TL;DR: In this paper, a comprehensive review of radiation effects due to γ-, β- and α-decay events, as well as from actinide doping experiments and particle irradiations, on nuclear waste form glasses and crystalline ceramics was provided.

582 citations


Journal ArticleDOI
TL;DR: The Peruvian case as discussed by the authors demonstrates that populism has been transformed rather than eclipsed during the neoliberal era and that it should be decoupled theoretically from any particular phase or model of economic development.
Abstract: Latin American populism is generally associated with the developmental stage of import substitution industrialization; it is thus widely presumed to have been eclipsed by the debt crisis of the 1980s and the free market reforms of the neoliberal era. However, the leadership of Alberto Fujimori in Peru suggests that new forms of populism may be emerging despite the fiscal constraints of neoliberal austerity. This new variant of populism thrives in a context where economic crisis and social dislocation undermine traditional representative institutions, enabling personalist leaders to establish unmediated relationships with heterogeneous, atomized masses. Political support can be cultivated through populist attacks on entrenched political elites or institutions, along with targeted but highly visible poverty alleviation programs. This new form of populist autocracy complements the efforts of neoliberal technocrats to circumvent the representative institutions that are integral to democratic accountability. The Peruvian case thus demonstrates that populism has been transformed rather than eclipsed during the neoliberal era and that it should be decoupled theoretically from any particular phase or model of economic development.

564 citations


DatasetDOI
05 Dec 1995
TL;DR: The DrInC is a self-administered 50-item questionnaire designed to measure adverse consequences of alcohol abuse in five areas: Interpersonal, Physical, Social, Impulsive, and Intrapersonal.
Abstract: ADMINISTRATIVE ISSUES The DrInC is a self-administered 50-item questionnaire designed to measure adverse consequences of alcohol abuse in five areas: Interpersonal, Physical, Social, Impulsive, and Intrapersonal. Each scale provides a lifetime and past 3-month measure of adverse consequences, and scales can be combined to assess total adverse consequences. Normative data are available for interpreta­ tion of client scale scores, and a brief version of the DrInC, the Short Index of Problems (SIP), is available when assessment time is limited.

558 citations


Journal ArticleDOI
TL;DR: In this article, the authors found that the more often an industry incumbent was among the first to introduce important incremental product innovations, the greater its market share in the industry, while adopting innovations that had been introduced by competitors had a small positive relationship with greater market share.
Abstract: Incremental product innovation is a critically important competitive factor in established industries. Firms in the cardiac pacemaker industry often benefit by bringing incremental innovations to market even though the new products may cannibalize the sales of existing profitable products. The more often an industry incumbent was among the first to introduce important incremental product innovations the greater its market share in the industry, while adopting innovations that had been introduced by competitors had a small positive relationship with greater market share. The greater the number of competitors that introduced similar products, the greater the market share of firms that were first to market. Greater market share, in turn, reduced the likelihood of business dissolution, while introducing important incremental innovations provided little or no reduction in the likelihood of business dissolution net of the effects of the market share that the firm achieved. The results apply most directly to industries in which buyers incur moderate switching costs.

Journal ArticleDOI
TL;DR: The growing number of empirical studies performed in ecology and evolution creates a need for quantitative summaries of research domains to generate higher-order conclusions about general trends and patterns.
Abstract: The growing number of empirical studies performed in ecology and evolution creates a need for quantitative summaries of research domains to generate higher-order conclusions about general trends and patterns. Recent developments In meta-analysis (the area of statistics that is designed for summarizing and analyzing multiple independent studies) have opened up new and exciting possibilities. Unlike more traditional qualitative and narrative reviews, meta-analysis allows powerful quantitative analyses of the magnitude of effects and has a high degree of objectivity because it is based on a standardized set of statistical procedures. The first pioneering applications in ecology and evolution demonstrate that meta-analysis is both tractable and powerful.

Journal ArticleDOI
01 Aug 1995-Sleep
TL;DR: Comparison of the risk and benefit of oral appliance therapy with the other available treatments suggests that oral appliances present a useful alternative to continuous positive airway pressure (CPAP), especially for patients with simple snoring and patients with obstructive sleep apnea who cannot tolerate CPAP therapy.
Abstract: This paper, which has been reviewed and approved by the Board of Directors of the American Sleep Disorders Association, provides the background for the Standards of Practice Committee's parameters for the practice of sleep medicine in North America. The 21 publications selected for this review describe 320 patients treated with oral appliances for snoring and obstructive sleep apnea. The appliances modify the upper airway by changing the posture of the mandible and tongue. Despite considerable variation in the design of these appliances, the clinical effects are remarkably consistent. Snoring is improved and often eliminated in almost all patients who use oral appliances. Obstructive sleep apnea improves in the majority of patients; the mean apnea-hypopnea index (AHI) in this group of patients was reduced from 47 to 19. Approximately half of treated patients achieved an AHI of < 10; however, as many as 40% of those treated were left with significantly elevated AHIs. Improvement in sleep quality and sleepiness reflects the effect on breathing. Limited follow-up data indicate that oral discomfort is a common but tolerable side effect, that dental and mandibular complications appear to be uncommon and that long-term compliance varies from 50% to 100% of patients. Comparison of the risk and benefit of oral appliance therapy with the other available treatments suggests that oral appliances present a useful alternative to continuous positive airway pressure (CPAP), especially for patients with simple snoring and patients with obstructive sleep apnea who cannot tolerate CPAP therapy.

Journal ArticleDOI
TL;DR: In this article, the generalized lagging behavior in solids under high-rate heating is derived by precise correlation with the hyperbolic two-step model, where the ballistic behavior of heat transport in the electron gas is captured by the second-order effect of the phase lag of the heat flux vector.

Proceedings ArticleDOI
01 May 1995
TL;DR: Space-scale diagrams provide an analytic framework for much of this work by representing both a spatial world and its different magnifications explicitly, which allows the direct visualization and analysis of important scale related issues for interfaces.
Abstract: Big information worlds cause big problems for interfaces. There is too much to see. They are hard to navigate. An armada of techniques has been proposed to present the many scales of information needed. Space-scale diagrams provide an analytic framework for much of this work. By representing both a spatial world and its different magnifications explicitly, the diagrams allow the direct visualization and analysis of important scale related issues for interfaces.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the lagging behavior for heat transport in small-scale and fast-transient processes and employed the phase-lag concept to describe the special response observed in these experiments.
Abstract: This work examines the lagging behavior for heat transport in small-scale and fast-transient processes. The experimental result by Qiu et al. for the femtosecond transient response in gold films and that by Bertman and Sandiford for the temperature pulse traveling through superfluid liquid helium are re-examined with emphasis on the lagging behavior. The model employing the phase-lag concept provides as competent or even better results when describing the special response observed in these experiments.

Book
01 Jan 1995
TL;DR: The nature of gesture, signed and spoken languages differently organized, and the origin of syntax: gesture as name and relation are discussed.
Abstract: This book proposes a radical alternative to dominant views of the evolution of language, and in particular the origins of syntax. The authors argue that manual and vocal communication developed in parallel, and that the basic elements of syntax are intrinsic to gesture. They draw on evidence from areas such as primatology, anthropology, and linguistics, to present a groundbreaking account of the notion that language emerged through visible bodily action. They go on to examine the implications of their findings for linguistic theory and theories of the biological evolution of the capacity for language. Written in a clear and accessible style, Gesture and the Nature of Language will be indispensable reading for all those interested in the origins of language.

Journal ArticleDOI
TL;DR: The Survey of Attitudes Toward Statistics (SATS) as mentioned in this paper was designed for use in both research and instruction, and a panel of instructors and introductory statistics students identified by consensus four facets of attitudes toward statistics: affect-positive and negative feelings concerning statistics; cognitive competence-attitudes about intellectual knowledge and skills when applied to statistics; value-attitude about the usefulness, relevance, and worth of statistics.
Abstract: The Survey of Attitudes Toward Statistics (SATS) was designed for use in both research and instruction. A panel of instructors and introductory statistics students identified by consensus four facets of attitudes toward statistics: (a) Affect-positive and negative feelings concerning statistics; (b) Cognitive Competence-attitudes about intellectual knowledge and skills when applied to statistics; (c) Value-attitudes about the usefulness, relevance, and worth of statistics; and (d) Difficulty-attitudes about the difficulty of statistics as a subject. This structure was validated for a sample of undergraduate students using confirmatory factor analysis. Additional validity evidence was obtained through the correlation of the SATS with Wise's Attitudes Toward Statistics scale, which showed significant, positive relationships between the two instruments.

Book
01 Aug 1995
TL;DR: In this paper, the authors compare historical antecedents of national administrative systems administration in more developed nations and less developed nations, and present some variations in administrative system administration in less-developed nations.
Abstract: Comparison in the study of public administration a focus for comparison concepts of system transformation historical antecedents of national administrative systems administration in more developed nations - general characteristics and classicadministrative systems administration in more developed nations - some variations in administrative systems administration in less developed nations bureaucratic-prominent political regimes party-prominent political regimes an overview ofbureaucracies and political systems.

Journal ArticleDOI
01 Jun 1995-Nature
TL;DR: In this article, a dip-coating method was proposed for aerogels without the need for supercritical extraction of the pore fluid from a wet gel, which prevents the network collapse that is otherwise induced by capillary forces.
Abstract: HIGHLY porous inorganic films have potential applications as dielectric materials, reflective and anti-reflective coatings, flat-panel displays, sensors, catalyst supports and super-insulating architectural glazings1–3. Aerogels4 are the most highly porous solids known, and can now be prepared from inorganic5 and organic6,7 precursors with volume-fraction porosities of up to 99.9% (ref. 8). Aerogels are normally prepared by supercritical extraction of the pore fluid from a wet gel1, which prevents the network collapse that is otherwise induced by capillary forces. But supercritical processing is expensive, hazardous and incompatible with the processing requirements of many potential applications,thus severely restricting the commercial exploitation of aerogels. Here we describe a means of preparing aerogels by a simple dip-coating method at ambient pressure without the need for supercriti-cal extraction. We add surface groups to the inorganic gel which make drying shrinkage reversible9: as the solvent is withdrawn, the gel springs back to a porous state. We can generate aerogel films with 98.5% porosity using this approach. We anticipate that it will greatly expand the commercial applications of these materials.

Journal ArticleDOI
TL;DR: Issues suggest that the increases with age in the prevalences of overweight and obesity, and in the risks for chronic diseases, may be mis-estimated using BMI and WHR.
Abstract: Obesity and body fat distribution (FD) are established risk factors for chronic diseases. The body mass index (BMI) and the waist/hip circumference ratio (WHR) are used conventionally as indices of obesity and FD in epidemiological studies. Although some general limitations of these indices are recognized, others that affect their use in relative risks for disease are not well recognized. These include effects of sex, ethnicity, and especially age on the relationships between these indices and body composition, which can result in substantial misclassification of obesity and FD. There is considerable variability in body composition for any BMI, and some individuals with low BMIs have as much fat as those with high BMIs. This results in poor sensitivity for classifying levels of body fatness (e.g., too many "false negatives," or overweight individuals classified as not overweight), and relative risks are attenuated across all categories of BMI. A more serious problem, however, is that at different ages the same levels of BMI correspond to different amounts of fat and fat-free mass. Data from the Rosetta Study and the New Mexico Aging Process Study show that older adults have, on average, more fat than younger adults at any BMI, due to the loss of muscle mass with age. As a result, the sensitivity of BMI cutpoints with respect to body fatness decreases with age, and the use of a fixed cutpoint for all ages results in "differential misclassification bias." Taken together, these issues suggest that the increases with age in the prevalences of overweight and obesity, and in the risks for chronic diseases, may be mis-estimated using BMI. Similar issues may affect the use of WHR for estimating prevalences and associated risks of FD. New field methods for estimating body composition are available that can be applied in large, epidemiologic follow-up studies of chronic diseases. These methods will allow epidemiologists to consider, for example, whether it is increased fat, or the replacement of fat-free mass with fat, with age that is associated with risk for chronic disease.

Journal ArticleDOI
TL;DR: The modified theory explains why damage to the hippocampal formation only impairs learning on a subset of nonlinear discrimination problems and makes novel predictions about performance on nonlineardiscrimination problems and place learning.
Abstract: Sutherland and Rudy ([1989] Psychobiology 17:129–144) proposed that the hippocampal system is critical to normal learning and memory because of its function as the central part of a configural association system. This system constructs a unique representation of the joint occurrence of the independent elements of a compund. There is evidence consistent with the theory's predictions, however, there also are data that unambiguously demonstrate that, under some conditions, animals lacking an intact hippocampal system acquire configural associations. Thus, Sutherland and Rudy's fundamental assumption cannot be correct. To integrate the supporting and contradictory data, we propose two simple modifications of our position: (1) The critical neural system for configural associations is in cortical circuitry outside the hippocampus, and (2) the output from the hippocampal formation contributes to configural processing by selectively enhancing, thereby making more salient, cortical units representing stimulus conjunctions. This enhancement has two important effects: (1) It decreases the similarity between the configural units representing the co-occurrence of cues and the units representing the cues, and (2) it increases the rate at which the configural units can acquire associative strength. The modified theory explains why damage to the hippocampal formation only impairs learning on a subset of nonlinear discrimination problems. It also integrates recent data on the effects of hippocampal formation damage on conditioning involving context cues and makes novel predictions about performance on nonlinear discrimination problems and place learning. © 1995 Wiley-Liss, Inc.


Journal ArticleDOI
TL;DR: Fat-free mass, body cell mass, and appendicular skeletal muscle decreased with age in both sexes, and Anthropometric indices, muscle area and waist/hip ratio, had low correlations with muscle mass and fat distribution.
Abstract: BACKGROUND There is little information for age differences in body composition in elderly people > 65 years of age, especially for those > 80 years. As the proportion of people older than 65 years is expected to nearly double during the next few decades, this information is needed. METHODS Age differences in body composition and anthropometry were examined in 316 men and women aged 60 to 95 years. Multiple components of body composition were quantified using dual energy X-ray absorptiometry and isotope dilution methods, and expressed in molecular and cellular models. Analysis of variance was used to test for differences between age groups 60 to 70, 71 to 80, and > 80 years in each sex. Body composition components were regressed on age, controlling for knee height, fat-free mass, or total body fat. Age-adjusted correlations were calculated with anthropometric variables. RESULTS Fat-free mass (FFM), body cell mass (BCM), and appendicular skeletal muscle (ASM) decreased with age in both sexes. ASM decreased relative to FFM in both the men and the women, while BCM decreased relative to FFM in the women only. Total fat mass and percent body fat decreased with age in the women, but not in the men. Body fat distribution did not appear to change with age. Anthropometric indices, muscle area and waist/hip ratio, had low correlations with muscle mass and fat distribution. CONCLUSIONS "Sarcopenia," or muscle loss, continues to occur into old age, and may have significant impacts on physical function and health status. New anthropometric techniques are needed for assessing muscle loss with age.

Journal ArticleDOI
TL;DR: In this paper, a self-regulation model predicts that feedback of undesirable deviation from normative standards would result in correction of behavior toward perceived norms, which may be a cost-effective strategy for reducing risky drinking.
Abstract: College students, particularly those who drink heavily, tend to overestimate the prevalence of heavy drinking among their peers. A self-regulation model predicts that feedback of undesirable deviation from normative standards would result in correction of behavior toward perceived norms. From a screening of 568 college students, sixty-four heavy drinkers were identified and offered the opportunity to participate in a survey study of drinking. Of these, twenty-six accepted and returned questionnaires with detailed information regarding their drinking practices. These were randomized to receive or not receive, by return mail, personal feedback of their drinking relative to population norms. At an independent follow-up interview, feedback subjects showed greater reduction in weekly consumption and typical intoxication levels, relative to controls. This simple feedback intervention, requiring no personal contact, may be a cost-effective strategy for reducing risky drinking.

Journal ArticleDOI
TL;DR: High-order frequency mixing experiments using the radiation of a high-power Ti:sapphire laser and its second harmonic are described and discussed and a three-dimensional quantum-mechanical calculation with a delta-function potential has been applied, showing quite good agreement with the experiments.
Abstract: High-order frequency mixing experiments using the radiation of a high-power Ti:sapphire laser and its second harmonic are described and discussed. Linearly and circularly polarized light fields with comparable intensities have been used. For the theoretical description a three-dimensional quantum-mechanical calculation with a \ensuremath{\delta}-function potential has been applied, showing quite good agreement with the experiments.

Journal ArticleDOI
TL;DR: This article traces the emergence of the basic paradigm for early diffusion research created by two rural sociologists at Iowa State University, Bryce Ryan and Neal C. Gross.
Abstract: This article traces the emergence of the basic paradigm for early diffusion research created by two rural sociologists at Iowa State University, Bryce Ryan and Neal C. Gross. The diffusion paradigm spread to an invisible college of midwestern rural sociological researchers in the 1950s and 1960s, and then to a larger, interdisciplinary field of diffusion scholars. By the late 1960s, rural sociologists lost interest in diffusion studies, not because it was ineffective scientifically, but because of lack of support for such study as a consequence of farm overproduction and because most of the interesting research questions were thought to be answered.

Journal ArticleDOI
TL;DR: In this article, the authors proposed that zircon be used as a waste form for the disposal of the more than 100 metric tons of plutonium that will result from the dismantling of nuclear weapons.
Abstract: Zircon, ZrSiO4, is a well-characterized, naturally occurring phase that is extremely durable. Zircon has been synthesized with Pu-concentrations up to 10 wt. % and radiation-damage effects studied to saturation doses of nearly 0.8 displacements per atom. We propose that zircon be used as a waste form for the disposal of the more than 100 metric tons of plutonium that will result from the dismantling of nuclear weapons. There are already several demonstrated processing technologies, of which hot pressing offers the most potential. This highly durable material, even under hydrothermal conditions, with its high waste loading and smaller volume allows deep, permanent disposal of the weapons plutonium in geologic environments in which the borosilicate waste-form glass would not be stable.

Journal ArticleDOI
TL;DR: In this article, the authors compare vote choice in U.S. Senate and gubernatorial elections from 1986 and 1990 with two retrospective voting hypotheses: the national referendum hypothesis and an economic retrospective hypothesis, and find that different types of retrospective evaluations are used with respect to vote choice.
Abstract: We compare vote choice in senate and gubernatorial elections from 1986 and 1990 with two retrospective voting hypotheses: the national referendum hypothesis and an economic retrospective hypothesis. Despite the similarities between the office of U.S. senator and governor (same constituency, high levels of campaign spending, highly visible candidates, etc.), we find that different types of retrospective evaluations are used with respect to vote choice. As members of the national legislative branch, senators' fortunes are linked to the success or failures of the president. In contrast, governors, as state executives, are held accountable for perceived state economic conditions, while senators escape unscathed from the same general economic evaluations. These findings shed some light on the nature of vote choice in a political system complicated by federalism and separation of powers.

Journal ArticleDOI
TL;DR: A series of meso-tetrasubstituted porphyrins for which the substituents vary in size is investigated, expected to result in unique alterations of the chemical and physical properties of the nominally planar p Morphyrin macrocycle.
Abstract: Metalloporphyrins undergo remarkable nonplanar distortions of the macrocycle that perturb the chemical and photochemical properties of these important protein cofactors. Further, the tertiary structure of the surrounding protein can manipulate these distortions as a means of regulating biological function. For cytochromes c, for example, an energetically unfavorable, conserved nonplanar distortion of the heme exists and likely plays a role in its electron- transfer function. The heme distortion is primarily of the ruffling (ruf, type (corresponding to the lowest frequency BI,-symmetry normal mode) in which the pyrroles are twisted about the metal-Npyrrole bond. This BI.-symmetry nonplanar distortion is commonly observed in metalloporphyrin crystal structures, as are the saddling (sad) B2,- symmetry distortion, waving (wau) E,-symmetry distortions, and doming (dom) Az,-symmetry distortion. Each of these nonplanar distortions is expected to result in unique alterations of the chemical and physical properties of the nominally planar porphyrin macrocycle. Symmetrical porphyrin substitution with tetrahedrally bonded atoms at the four meso bridging carbons generally results in the BI, ruffling distortion; therefore, we investigated a series of meso-tetrasubstituted porphyrins for which the substituents vary in size (methyl, ethyl, propyl, pentyl, isopropyl, cyclopropyl derivative lla, cyclohexyl, apopinenyl (lo), tert-butyl, adamantyl), increasing the steric crowding at the periphery. Molecular mechanics calculations show increasing degree of ruffling (CaNNCa angle for opposite pyrroles varies from 0 to 57") for this series of porphyrins, generally agreeing with the X-ray structures that are available. In addition, the frequencies of the structure-sensitive Raman lines decrease nonlinearly with increasing ruffling angle. The localization of the Bl, nonplanar distortion in only the C,-C, bond torsion (not the case for the B2" sad distortion) suggests a means by which the B1, distortion might be distinguished from other types of nonplanar distortion by using resonance Raman spectroscopy. Also, the size of the red shifts in the n - n* absorption bands depends on Ca-Cm torsion angle in a nonlinear fashion and the shift is accurately predicted by INDO/s molecular orbital calculations when the nonplanar structures obtained from molecular mechanics are used.