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Constraints
Kinds of Constraints Terms modified by Constraints Selected AbstractsEVOLUTIONARY CONSTRAINT AND ECOLOGICAL CONSEQUENCESEVOLUTION, Issue 7 2010Douglas J. Futuyma One of the most important shifts in evolutionary biology in the past 50 years is an increased recognition of sluggish evolution and failures to adapt, which seem paradoxical in view of abundant genetic variation and many instances of rapid local adaptation. I review hypotheses of evolutionary constraint (or restraint), and suggest that although constraints on individual characters or character complexes may often reside in the structure or paucity of genetic variation, organism-wide stasis, as described by paleontologists, might better be explained by a hypothesis of ephemeral divergence, according to which the spatial or temporal divergence of populations is often short-lived because of interbreeding with nondivergent populations. Among the many consequences of acknowledging evolutionary constraints, community ecology is being transformed as it takes into account phylogenetic niche conservatism and the strong imprint of deep history. [source] INTERGENOMIC EPISTASIS AND COEVOLUTIONARY CONSTRAINT IN PLANTS AND RHIZOBIAEVOLUTION, Issue 5 2010Katy D. Heath Studying how the fitness benefits of mutualism differ among a wide range of partner genotypes, and at multiple spatial scales, can shed light on the processes that maintain mutualism and structure coevolutionary interactions. Using legumes and rhizobia from three natural populations, I studied the symbiotic fitness benefits for both partners in 108 plant maternal family by rhizobium strain combinations. Genotype-by-genotype (G × G) interactions among local genotypes and among partner populations determined, in part, the benefits of mutualism for both partners; for example, the fitness effects of particular rhizobium strains ranged from uncooperative to mutualistic depending on the plant family. Correlations between plant and rhizobium fitness benefits suggest a trade off, and therefore a potential conflict, between the interests of the two partners. These results suggest that legume,rhizobium mutualisms are dynamic at multiple spatial scales, and that strictly additive models of mutualism benefits may ignore dynamics potentially important to both the maintenance of genetic variation and the generation of geographic patterns in coevolutionary interactions. [source] CONVERGENCE AND REMARKABLY CONSISTENT CONSTRAINT IN THE EVOLUTION OF CARNIVORE SKULL SHAPEEVOLUTION, Issue 5 2007Stephen Wroe Phenotypic similarities between distantly related marsupials and placentals are commonly presented as examples of convergence and support for the role of adaptive evolution in shaping morphological and ecological diversity. Here we compare skull shape in a wide range of carnivoran placentals (Carnivora) and nonherbivorous marsupials using a three-dimensional (3-D) geometric morphometric approach. Morphological and ecological diversity among extant carnivorans is considerably greater than is evident in the marsupial order Dasyuromorphia with which they have most commonly been compared. To examine convergence across a wider, but broadly comparable range of feeding ecologies, a dataset inclusive of nondasyuromorphian marsupials and extinct taxa representing morphotypes no longer present was assembled. We found support for the adaptive paradigm, with correlations between morphology, feeding behavior, and bite force, although skull shape better predicted feeding ecology in the phylogenetically diverse marsupial sample than in carnivorans. However, we also show that remarkably consistent but differing constraints have influenced the evolution of cranial shape in both groups. These differences between carnivorans and marsupials, which correlate with brain size and bite force, are maintained across the full gamut of morphologies and feeding categories, from small insectivores and omnivores to large meat-specialists. [source] PERSPECTIVE: EMBEDDED MOLECULAR SWITCHES, ANTICANCER SELECTION, AND EFFECTS ON ONTOGENETIC RATES: A HYPOTHESIS OF DEVELOPMENTAL CONSTRAINT ON MORPHOGENESIS AND EVOLUTIONEVOLUTION, Issue 5 2003Kathryn D. Kavanagh Abstract The switch between the cell cycle and the progress of differentiation in developmental pathways is prevalent throughout the eukaryotes in all major cell lineages. Disruptions to the molecular signals regulating the switch between proliferative and differentiating states are severe, often resulting in cancer formation (uncontrolled proliferation) or major developmental disorders. Uncontrolled proliferation and developmental disorders are potentially lethal defects in the developing animal. Therefore, natural selection would likely favor a tightly controlled regulatory mechanism to help prevent these fundamental defects. Although selection is usually thought of as a consequence of environmental or ecological influences, in this case the selective force to maintain this molecular switch is internal, manifested as a potentially lethal developmental defect. The morphogenetic consequences of this prevalent, deeply embedded, and tightly controlled mechanistic switch are currently unexplored, however experimental and correlative evidence from several sources suggest that there are important consequences on the control of growth rates and developmental rates in organs and in the whole animal. These observations lead one to consider the possibility of a developmental constraint on ontogenetic rates and morphological evolution maintained by natural selection against cancer and other embryonic lethal defects. [source] THE ECONOMICS OF THE NON-DISTRIBUTION CONSTRAINT: A CRITICAL REAPPRAISALANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 1 2008Vladislav VALENTINOV ABSTRACT,:,This paper re-examines the non-distribution constraint as a key structural feature of non-profit organization. It argues that its traditional understanding as a trustworthiness-enhancing device is incomplete. This paper shows that the non-distribution constraint is also a reflection of the directly utility-enhancing character of involvement in non-profit firms for their key stakeholders. This alternative explanation allows one to solve the central puzzle of trustworthiness theory: why doesn't the non-distribution constraint destroy entrepreneurial motivation? Additionally, it helps one to understand the role of the non-distribution constraint in economic theories of non-profit organization that do not rely on trustworthiness theory. Finally, it enables one to logically integrate the different economic theories of non-profit organization. [source] STOP US BEFORE WE SPEND AGAIN: INSTITUTIONAL CONSTRAINTS ON GOVERNMENT SPENDINGECONOMICS & POLITICS, Issue 3 2006DAVID M. PRIMO A distributive politics model establishes that the presence of exogenously enforceable spending limits reduces spending and that the effect of executive veto authority is contingent on whether spending is capped and whether the chief executive is a liberal or conservative. Surprisingly, when spending limits are in place, governments with conservative executives spend more than those with more liberal chief executives. Limits are welfare improving, as is the executive veto when it leads to the building of override coalitions. Using 32 years of US state budget data, this paper also establishes empirically that strict balanced budget rules constrain spending and also lead to less pronounced short-term responses to fluctuations in a state's economy. Party variables like divided government and party control of state legislatures tend to have little or no direct effect, with political institutions and economic indicators explaining much of the variation in state spending. [source] ADAPTIVE CONSTRAINTS AND THE PHYLOGENETIC COMPARATIVE METHOD: A COMPUTER SIMULATION TESTEVOLUTION, Issue 1 2002Emilia P. Martins Abstract Recently, the utility of modern phylogenetic comparative methods (PCMs) has been questioned because of the seemingly restrictive assumptions required by these methods. Although most comparative analyses involve traits thought to be undergoing natural or sexual selection, most PCMs require an assumption that the traits be evolving by less directed random processes, such as Brownian motion (BM). In this study, we use computer simulation to generate data under more realistic evolutionary scenarios and consider the statistical abilities of a variety of PCMs to estimate correlation coefficients from these data. We found that correlations estimated without taking phylogeny into account were often quite poor and never substantially better than those produced by the other tested methods. In contrast, most PCMs performed quite well even when their assumptions were violated. Felsenstein's independent contrasts (FIC) method gave the best performance in many cases, even when weak constraints had been acting throughout phenotypic evolution. When strong constraints acted in opposition to variance-generating (i.e., BM) forces, however, FIC correlation coefficients were biased in the direction of those BM forces. In most cases, all other PCMs tested (phylogenetic generalized least squares, phylogenetic mixed model, spatial autoregression, and phylogenetic eigenvector regression) yielded good statistical performance, regardless of the details of the evolutionary model used to generate the data. Actual parameter estimates given by different PCMs for each dataset, however, were occasionally very different from one another, suggesting that the choice among them should depend on the types of traits and evolutionary processes being considered. [source] SPATIAL CONSTRAINTS ON WOMEN'S WORK IN TARIJA, BOLIVIAGEOGRAPHICAL REVIEW, Issue 2 2000Article first published online: 21 APR 2010, KATHLEEN SCHROEDER ABSTRACT. This geography of women's work in the less-developed world is set in Tarija, Bolivia, a small city that has been dramatically changed by economic crisis and structural-adjustment programs. Explored is the spatial component of women's economic activities in a low-income barrio following the imposition of structural-adjustment programs in the 1980s and 1990s. Women who pursue employment away from home must rely on other women. In particular, households that include more than one woman who is capable of handling important daily chores are more likely to have a woman engaged in income-generating activities away from the home and the neighborhood. Women at home make it possible for other women to extend their economic activity into the broader community. These findings are important because they draw attention to women's reliance on other women, how women use space, and how they are constrained by spatial factors as they negotiate their daily lives. [source] CREDIT CONSTRAINTS IN THE MARKET FOR CONSUMER DURABLES: EVIDENCE FROM MICRO DATA ON CAR LOANS,INTERNATIONAL ECONOMIC REVIEW, Issue 2 2008Orazio P. Attanasio We investigate the significance of borrowing constraints in the market for consumer loans. Using data from the Consumer Expenditure Survey on auto loan contracts we estimate the elasticities of loan demand with respect to interest rate and maturity. We find that, with the exception of high income households, consumers are very responsive to maturity and less responsive to interest rate changes. Both elasticities vary with household income, with the maturity elasticity decreasing and the interest rate elasticity increasing with income. We argue that these results are consistent with the presence of binding credit constraints in the auto loan market. [source] CONSTRAINTS ON DIAGENESIS AND RESERVOIR QUALITY IN THE FRACTURED HASDRUBAL FIELD, OFFSHORE TUNISIAJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2001C. I. Macaulay The hydrocarbon reservoir of the Hasdrubal field (offshore Tunisia) lies within the Eocene El Garia Formation. This formation was deposited on a shallow north- to NE-facing ramp in the Early Eocene and is composed of a belt of nummulitic wackestones-grainstones. The nummulitic fades occupies a range of depositional environments from outer to mid ramp. In addition to Hasdrubal, several other producing oil- and gasfields have been discovered in the variably dolomitised El Garia Formation offshore Tunisia. Cores from three Hasdrubal wells were examined. Reservoir quality shows a limited relationship to primary depositional fabric and has been influenced significantly by compaction and later diagenesis. The highest permeabilities are typically developed within a dolomitised zone which occurs near the middle of the reservoir interval across the entire field, and which may follow a primary wackestone lithofabric (typically 20,30% bulk volume dolomite, with porosities of 15,22% and permeabilities of l-30mD). Fractures, particularly in zones surrounding faults, have resulted in enhanced permeabilities. Combined results of isotope (,18 O -5.0 to -7.3%oPDB) and fluid inclusion (Th 80,90d,C) analyses of dolomites from this dolomitised zone indicate that matrix dolomites are burial diagenesis cements. Dolomitisation of the reservoir was a "closed system " event and was not the result of major fluid flow or mixing. Magnesium ions for dolomitisation were derived from the transformation of high-Mg to low-Mg calcite in nummulite tests within the reservoir fades. Our analyses indicate that calcite cements were precipitated at temperatures of up to almost 150d,C in primary and secondary pores and in variably-sealed fractures Fracture lining and filling cements show a range of ,18 O values, which suggests that the fractures acted as fluid conduits over a range of temperatures during burial diagenesis Fracture densities measured in core increase rapidly close to seismically-resolvable faults in the reservoir facies Fracturing probably resulted in the leakage of hydrocarbons through the Compact Micrite Member seal which overlies the accumulation, as well as facilitating the ingress of hot fluids from stratigraphically deeper levels in the basin [source] METABOLIC AND ECOLOGICAL CONSTRAINTS IMPOSED BY SIMILAR RATES OF AMMONIUM AND NITRATE UPTAKE PER UNIT SURFACE AREA AT LOW SUBSTRATE CONCENTRATIONS IN MARINE PHYTOPLANKTON AND MACROALGAE,JOURNAL OF PHYCOLOGY, Issue 2 2007T. Alwyn Marine phytoplankton and macroalgae acquire important resources, such as inorganic nitrogen, from the surrounding seawater by uptake across their entire surface area. Rates of ammonium and nitrate uptake per unit surface area were remarkably similar for both marine phytoplankton and macroalgae at low external concentrations. At an external concentration of 1 ,M, the mean rate of nitrogen uptake was 10±2 nmol·cm,2·h,1 (n=36). There was a strong negative relationship between log surface area:volume (SA:V) quotient and log nitrogen content per cm2 of surface (slope=,0.77), but a positive relationship between log SA:V and log maximum specific growth rate (,max; slope=0.46). There was a strong negative relationship between log SA:V and log measured rate of ammonium assimilation per cm2 of surface, but the slope (,0.49) was steeper than that required to sustain ,max (,0.31). Calculated rates of ammonium assimilation required to sustain growth rates measured in natural populations were similar for both marine phytoplankton and macroalgae with an overall mean of 6.2±1.4 nmol·cm,2·h,1 (n=15). These values were similar to maximum rates of ammonium assimilation in phytoplankton with high SA:V, but the values for algae with low SA:V were substantially less than the maximum rate of ammonium assimilation. This suggests that the growth rates of both marine phytoplankton and macroalgae in nature are often constrained by rates of uptake and assimilation of nutrients per cm2 surface area. [source] PORTFOLIO OPTIMIZATION WITH DOWNSIDE CONSTRAINTSMATHEMATICAL FINANCE, Issue 2 2006Peter Lakner We consider the portfolio optimization problem for an investor whose consumption rate process and terminal wealth are subject to downside constraints. In the standard financial market model that consists of d risky assets and one riskless asset, we assume that the riskless asset earns a constant instantaneous rate of interest, r > 0, and that the risky assets are geometric Brownian motions. The optimal portfolio policy for a wide scale of utility functions is derived explicitly. The gradient operator and the Clark,Ocone formula in Malliavin calculus are used in the derivation of this policy. We show how Malliavin calculus approach can help us get around certain difficulties that arise in using the classical "delta hedging" approach. [source] CONSTRAINTS ON SCEPTICAL HYPOTHESESTHE PHILOSOPHICAL QUARTERLY, Issue 240 2010James R. Beebe I examine the conditions which hypotheses must satisfy if they are to be used to raise significant sceptical challenges. I argue that sceptical hypotheses do not have to be logically, metaphysically or epistemically possible: they need only to depict scenarios subjectively indistinguishable from the actual world and to show how subjects can believe what they do while not having knowledge. I also argue that sceptical challenges can be raised against a priori beliefs, even if those beliefs are necessarily true. I hope to broaden our conception of the legitimate kinds of sceptical challenges which can be raised. [source] FINANCIAL CONSTRAINTS AND TECHNICAL EFFICIENCY: SOME EMPIRICAL EVIDENCE FOR ITALIAN PRODUCERS' COOPERATIVESANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 1 2010Ornella Wanda Maietta ABSTRACT,:,In this paper, we test the extent to which producers' cooperatives can experience an increase in technical efficiency following a tightening of financial constraints. This hypothesis is tested on a sample of Italian conventional and cooperative firms for the wine production and processing sector, using frontier analysis. The results support the hypothesis that increasing financial pressure can affect positively the cooperatives efficiency. [source] A BUREAUCRAT'S PROCUREMENT STRATEGY: BUDGET CONSTRAINTS AND RATIONINGANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 2 2007Signe ANTHON ABSTRACT,:,We investigate a bureaucratic principal responsible for the procurement of goods and services from private agents. The bureaucrat is evaluated on output and controlled by a limited budget. The agents maximize profit, have private information about variable production costs, and have positive outside options which are lost upon acceptance of a procurement contract. The setting is relevant for, e.g. governmental agencies. We show how this setup makes probabilistic rationing and overproduction for low-cost agents a useful tool for the bureaucrat. [source] ROBUST OUTPUT FEEDBACK CONTROLLER DESIGN WITH COVARIANCE AND DISC CLOSED-LOOP POLE CONSTRAINTSASIAN JOURNAL OF CONTROL, Issue 3 2005Li Yu ABSTRACT This paper is concerned with the problem of robust output feedback controller design for a class of linear discrete-time systems with normbounded uncertainty. The objective is to design a controller such that the closed-loop poles are assigned within a specified disc and the steady regulated output covariance is guaranteed to be less than a given upper bound. Using a linear matrix inequality (LMI) approach, the existence conditions of such controllers are derived, and a parametrized characterization of a set of desired controllers (if they exist) is presented in terms of the feasible solutions to a set of LMIs. A procedure is given to select a suitable output feedback controller that minimizes the desired control effort. [source] STEERING A MOBILE ROBOT: SELECTION OF A VELOCITY PROFILE SATISFYING DYNAMICAL CONSTRAINTSASIAN JOURNAL OF CONTROL, Issue 4 2000M.A. Benayad ABSTRACT We present an open loop control design allowing to steer a wheeled mobile robot along a prespecified smooth geometric path, minimizing a given cost index and satisfying a set of dynamical constraints. Using the concept of "differential flatness," the problem is equivalent to the selection of the optimal time parametrization of the geometric path. This parametrization is characterized by a differential equation involving a function of the curvilinear coordinate along the path. For the minimum time problem, as well as for another index (such as the maximum value of the centripetal acceleration) to be minimized over a given time interval, the problem then reduces to the optimal choice of this function of the curvilinear coordinate. Using spline functions interpolation, the problem can be recast as a finite parameter optimization problem. Numerical simulation results illustrate the procedure. [source] NON-SYMMETRICAL CORRESPONDENCE ANALYSIS WITH CONCATENATION AND LINEAR CONSTRAINTSAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 1 2010Eric J. Beh Summary Correspondence analysis is a popular statistical technique used to identify graphically the presence, and structure, of association between two or more cross-classified categorical variables. Such a procedure is very useful when it is known that there is a symmetric (two-way) relationship between the variables. When such a relationship is known not to exist, non-symmetrical correspondence analysis is more appropriate as a method of establishing the source of association. This paper highlights some tools that can be used to explore the behaviour of asymmetric categorical variables. These tools consist of confidence regions, the link between non-symmetrical correspondence analysis and the analysis of variance of categorical variables, and the effect of imposing linear constraints. We also explore the application of non-symmetrical correspondence analysis to three-way contingency tables. [source] Social Inequality in Education: A Constraint on an American High-Skills FutureCURRICULUM INQUIRY, Issue 4 2007THEODORE LEWIS ABSTRACT Countries everywhere are turning to education in the quest for competitive edge in the global economy. How to attain the high skills needed in new reformed workplaces is a preoccupation that can be observed across developed countries. In this widening discourse of high skills and competitiveness, the U.S. skills production model is being seen as undesirable because it is perceived to be premised upon educational inequality and skills polarization. This article agrees with such characterization of the U.S educational condition. It examines skill tendencies in new reformed workplaces and conceptions of how schools must respond, then interrogates assumptions underpinning college-bound/non-college,bound formulations that would have low socioeconomic status (SES) children pursuing watered-down academic fare, or vocational education, while high SES children are set on college pathways. I contend that curricula approaches that are premised on alternative post-school destinations leave the children of underclasses in the same unfavorable position as their parents, such curricula serving only to reproduce inequality. The article rejects curriculum tracking, and the notion of the non-college bound, and instead argues for the democratization of high status knowledge as the best response to the challenge of a high-skills future. [source] Contrasting Patch Residence Strategy in Two Species of Sit-and-Wait Foragers Under the Same Environment: A Constraint by Life History?ETHOLOGY, Issue 2 2005Tadashi Miyashita The present study explored the significance of life history constraints on patch residence strategy by using two congeneric web spider species living in the same habitat. Nephila maculata had a large body size but had a shorter developmental period compared with N. clavata, indicating that N. maculata should have a greater foraging efficiency to reach maturity and reproduce. Residence time at web-sites in N. maculata was shorter than that in N. clavata, irrespective of the season. However, supplementation of food to N. maculata increased residence time, suggesting that it searches web-sites with higher prey intake. Investment of web materials, an important trait influencing web relocation frequency, was not greater in N. maculata. In addition, microhabitat and prey size did not differ significantly after controlling for the effect of body size. Because N. maculata needs to attain a large body size in a shorter period of time, this species appears to take a risk of moving patches to seek high quality web-sites. [source] Disinhibitory trait profile and its relation to Cluster B personality disorder features and substance use problemsEUROPEAN JOURNAL OF PERSONALITY, Issue 4 2006Jeanette Taylor Abstract Certain personality and motivational traits may present vulnerability towards disinhibitory psychopathology (e.g. antisocial personality disorder, substance abuse). Cluster analysis was used to separately group 306 women and 274 men on impulsivity, Constraint, Negative Emotionality, behavioural activation system (BAS), and behavioural inhibition system (BIS) scores. As expected, a ,disinhibited' group with low Constraint, high impulsivity, weak BIS, and strong BAS emerged that showed elevated drug use problems, and histrionic and antisocial personality disorder features across gender. A ,high affectivity' group with high Negative Emotionality and strong BIS also showed elevated drug use problems and personality disorder features. Results suggested that two different trait profiles are associated with disinhibitory psychopathology and both may present vulnerability toward the development of such disorders. Copyright © 2006 John Wiley & Sons, Ltd. [source] The assessment of behavioural activation,the relationship between positive emotionality and the behavioural activation systemEUROPEAN JOURNAL OF PERSONALITY, Issue 7 2004Lena C. Quilty Much personality research suggests that the variance in personality can be accounted for by a few dimensions, often hypothesized to be connected to neurological circuits. Gray's (1982) behavioural activation system (BAS) and behavioural inhibition system (BIS) in particular propose to explain for a variety of behaviour. This investigation sought to determine whether Positive Emotionality is an appropriate measure of the BAS, and how Tellegen's (1985) constructs are related to BAS activity. Measures of BAS and Positive Emotionality were administered to undergraduates. Confirmatory factor analyses revealed that, while Positive Emotionality can be used as an indicator of BAS activity, it is better conceived of as a distinct, correlated construct. In addition, not all components of Positive Emotionality were related to BAS activity, and BAS was further related to components of Negative Emotionality and Constraint. Copyright © 2004 John Wiley & Sons, Ltd. [source] A Pragmatic Response to an Unexpected Constraint: Problem Representation in a Complex Humanitarian EmergencyFOREIGN POLICY ANALYSIS, Issue 2 2009Thomas Knecht This paper elaborates a model of problem representation first presented by Billings and Hermann (1998). The foreign policy process begins when decision-makers specify policy goals and identify relevant constraints in response to a perceived problem. Although this initial problem representation often sets the course for subsequent policy, unanticipated constraints can arise that catch decision makers off-guard. Finding themselves in a context they did not anticipate to be in, decision makers may choose to alter their representation of the problem and/or change the course of policy. Billings and Hermann offer one piece of this puzzle by examining how decision makers re-represent problems; this paper provides the second piece by assessing how policies, not representations, change in response to new constraints. A case study of the U.S. response to the Ethiopian famine in the mid 1980s demonstrates that policy does not always follow problem representation. [source] Public Opinion as a Constraint against War: Democracies' Responses to Operation Iraqi FreedomFOREIGN POLICY ANALYSIS, Issue 2 2006STEVE CHAN A central logic of the democratic peace theory claims that public opinion acts as a powerful restraint against war. Democratic officials, unlike their autocratic counterparts, are wary of going to war because they expect to pay an electoral penalty for fighting even successful wars. Several democracies, however, recently joined Operation Iraqi Freedom despite substantial and even overwhelming domestic opposition. We argue that electoral institutions can heighten or lessen the impact of public opinion on democratic officials' concerns for their reelection prospects, thus pointing to an important dimension of variation that has been overlooked in the democratic peace literature. However, contrary to conventional attributions of a greater incentive motivating the parties and candidates in predominantly two-party systems with majority/plurality decision rules to respond to national public opinion, we suggest mitigating factors that tend to reduce such responsiveness. Conversely, we point out that multiparty competition in proportional representation systems can reduce electoral disproportionality without sacrificing responsiveness to public opinion. The pertinent electoral institutions therefore present varying opportunities (or, conversely, constraints) for democratic officials to override their constituents' sentiments when they are so inclined. [source] Hyperkalemia as a Constraint to Therapy With Combination Renin-Angiotensin System Blockade: The Elephant in the RoomJOURNAL OF CLINICAL HYPERTENSION, Issue 2 2009Murray Epstein MD First page of article [source] Stability and Change in Personality Traits From Late Adolescence to Early Adulthood: A Longitudinal Twin StudyJOURNAL OF PERSONALITY, Issue 2 2008Daniel M. Blonigen ABSTRACT We conducted a longitudinal-biometric study examining stability and change in personality from ages 17 to 24 in a community sample of male and female twins. Using Tellegen's (in press) Multidimensional Personality Questionnaire (MPQ), facets of Negative Emotionality (NEM) declined substantially at the mean and individual levels, whereas facets of Constraint (CON) increased over time. Furthermore, individuals in late adolescence who were lowest on NEM and highest on CON remained the most stable over time, whereas those exhibiting the inverse profile (higher NEM, lower CON) changed the most in a direction towards growth and maturity. Analyses of gender differences yielded greater mean-level increases over time for women as compared to men on facets of CON and greater mean-level increases for men than women on facets of Agentic Positive Emotionality (PEM). Biometric analyses revealed rank-order stability in personality to be largely genetic, with rank-order change mediated by both the nonshared environment (and error) as well as genes. Findings correspond with prior evidence of a normative trend toward growth and maturity in personality during emerging adulthood. [source] Constraint of Oxygen Fugacity During Field-Assisted Sintering: TiO2 as a Test CaseJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Dat V. Quach Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO2 as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite,CO,O2 equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10,16 atm, which is higher than the value obtained from thermodynamic equilibrium of graphite,CO,O2 at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase. [source] Thermal Cycling Damage Mechanisms of C/SiC Composites in Displacement Constraint and Oxidizing AtmosphereJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006Hui Mei A constraint stress of 62.5 MPa is created on a three-dimensional C/SiC composite specimen whose both ends are fixed when temperature is cycled between 900° and 1200°C. The cyclic stress results in a maximum damage strain of 0.06% within 50 cycles owing to coating and matrix cracking, fiber debonding, sliding, and breaking in the composite. This constrained specimen elongation also leads to a final compressive stress of 14 MPa on the composite through a decrease in the baseline constraint stress. Wet oxygen atmosphere at a high cyclic temperature, concomitant with stresses, can aggravate the damage situation by alternate oxidation between internal and external fibers in composites. [source] Prospective community-based cluster census and case-control study of stillbirths and neonatal deaths in the West Bank and Gaza StripPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 4 2008Henry D. Kalter Summary Obstetric complications and newborn illnesses amenable to basic medical interventions underlie most perinatal deaths. Yet, despite good access to maternal and newborn care in many transitional countries, perinatal mortality is often not monitored in these settings. The present study identified risk factors for perinatal death and the level and causes of stillbirths and neonatal deaths in the West Bank and Gaza Strip. Baseline and follow-up censuses with prospective monitoring of pregnant women and newborns from September 2001 to August 2002 were conducted in 83 randomly selected clusters of 300 households each. A total of 113 of 116 married women 15,49 years old with a stillbirth or neonatal death and 813 randomly selected women with a surviving neonate were interviewed, and obstetric and newborn care records of women with a stillbirth or neonatal death were abstracted. The perinatal and neonatal mortality rates, respectively, were 21.2 [95% confidence interval (CI) 16.5, 25.9] and 14.7 [95% CI 10.2, 19.2] per 1000 livebirths. The most common cause (27%) of 96 perinatal deaths was asphyxia alone (21) or with neonatal sepsis (5), while 18/49 (37%) early and 9/19 (47%) late neonatal deaths were from respiratory distress syndrome (12) or sepsis (9) alone or together (6). Constraint in care seeking, mainly by an Israeli checkpoint, occurred in 8% and 10%, respectively, of 112 pregnancies and labours and 31% of 16 neonates prior to perinatal or late neonatal death. Poor quality care for a complication associated with the death was identified among 40% and 20%, respectively, of 112 pregnancies and labour/deliveries and 43% of 68 neonates. (Correction added after online publication 5 June 2008: The denominators 112 pregnancies, labours, and labour/deliveries, and 16 and 68 neonates were included; and 9% of labours was corrected to 10%.) Risk factors for perinatal death as assessed by multivariable logistic regression included preterm delivery (odds ratio [OR] = 11.9, [95% CI 6.7, 21.2]), antepartum haemorrhage (OR = 5.6, [95% CI 1.5, 20.9]), any severe pregnancy complication (OR = 3.4, [95% CI 1.8, 6.6]), term delivery in a government hospital and having a labour and delivery complication (OR = 3.8, [95% CI 1.2, 12.0]), more than one delivery complication (OR = 4.4, [95% CI 1.8, 10.5]), mother's age >35 years (OR = 2.9, [95% CI 1.3, 6.8]) and primiparity in a full-term pregnancy (OR = 2.6, [1.1, 6.3]). Stillbirths are not officially reportable in the West Bank and Gaza Strip and this is the first time that perinatal mortality has been examined. Interventions to lower stillbirths and neonatal deaths should focus on improving the quality of medical care for important obstetric complications and newborn illnesses. Other transitional countries can draw lessons for their health care systems from these findings. [source] Content Ascriptions and the Reversibility ConstraintPHILOSOPHICAL PERSPECTIVES, Issue 1 2005Richard Price First page of article [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||