bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐random recruitment of invader species in experimental grasslands
Authors: Roscher Christiane , Schmid Bernhard , Schulze Ernst‐Detlef
Published: June 2009

To assess potential effects of seed limitation, characteristics of invader species and characteristics of established plant communities on recruitment success, we conducted a split‐plot experiment factorially combining three weeding treatments corresponding to increasing successional age (regular weeding<cessation of weeding after three years<never weeded since sowing) with two seed limitation treatments (control vs sowing a seed mixture of all experimental species=internal invaders) in experimental grasslands varying in species richness (1, 2, 4, 8, 16) and in functional group richness and composition (1, 2, 3, 4 functional groups: presence/absence of legumes×grasses×tall herbs×small herbs). Seed addition increased internal invader seedling densities and the probability of successful colonization per species. Legumes, tall herbs and species with large and long‐lived seeds or a requirement for specific vectors for pollination and dispersal benefited from seed addition most. The number of successfully established internal invader species was highest in plots with low initial species richness and in the regularly weeded treatments and lowest in plots with high initial species richness and in the never weeded treatments, indicating decreased recruitment with increased successional age. Resident plant communities with legumes had mostly negative (legume and small‐ and tall‐herb internal invaders, external invaders) or neutral (grass invaders) effects on seedling density and colonization probability of invader species whereas resident communities with grasses had positive effects on the colonization probability of invader species except grasses themselves. These results show that seed limitation, invader characteristics, and community characteristics all can affect recruitment success in predictable ways, suggesting non‐random community assembly during succession starting from different initial species pools.
Blood pressure support in extremely premature infants is affected by different courses of antenatal steroids
Authors: Nair GV , Omar SA
Published: June 2009

Objective:  To examine the effects of partial, single and multiple courses of antenatal corticosteroids (ANS) on the need for blood pressure support in extremely premature infants.

Methods:  Extremely premature infants with gestational age of 24 to 28 weeks were included in this study during a 5‐year period. The main outcome measure of the study was the amount of blood pressure support during the first 3 days of life.

Results:  The study infants (n = 163) were divided into: infants not exposed (ANS; n = 27) and exposed to ANS (ANS; n = 136). Blood pressure support was significantly lower in ANS compared with No ANS (65% vs 96%; p = 0.003) and in single course (SANS; n = 73) and ≥2 courses (MANS; n = 34) compared with partial course of ANS (PANS; n = 29) (62%, 56% vs 86%; p = 0.03). The number of infants who received volume support and the amount of volume support were significantly lower in ANS compared with that in No ANS (p < 0.001) and in SANS and MANS compared with that in PANS (p < 0.02).

Conclusion:  Exposure to multiple courses of ANS was as beneficial as single course of ANS in decreasing the need for blood pressure support in extremely premature infants.
Kangaroo Mother Care, home environment and father involvement in the first year of life: a randomized controlled study
Authors: Tessier R , Charpak N , Giron M , Cristo M , De Calume ZF , Ruiz‐Peláez JG
Published: June 2009

Aims:  This study tested the hypothesis that Kangaroo Mother Care creates a climate in the family, which enhances infants’ performance on the developmental quotient scale.

Setting:  The largest social security hospital in Colombia with a neonatal intensive care unit.

Subjects:  At 12 months of corrected age, 194 families in the Kangaroo Mother Care group and 144 families in the Traditional Care group were available for analysis.

Interventions:  Infants were kept 24 h/day in an upright position, in skin‐to‐skin contact until it was no longer tolerated by the infants. Babies in the Traditional Care were kept in incubators on the Minimal Care Unit until they satisfied the usual discharge criteria.

Outcome measures:  The Home Observation for Measurement of the Environment (HOME), Father Involvement and Developmental Quotient (Griffiths) scores.

Results:  1) Kangaroo mothers created a more stimulating context and a better caregiving environment than mothers in the Traditional Care group; 2) this environment was positively correlated to father involvement and 3) the family environment of male infants was most improved by Kangaroo Mother Care.

Conclusion:  Kangaroo Mother Care has a positive impact on home environment. The results also suggest, first, that both parents should be involved as direct caregivers in the Kangaroo Mother Care procedure and secondly, that this intervention should be directed more specifically at infants who are more at risk at birth. The Kangaroo Mother Care intervention could be an excellent means to ensure parents’ mature involvement in the future of their children.
Visual neurophysiological dysfunction in infants exposed to hydroxychloroquine in utero
Authors: Renault F , Flores‐Guevara R , Renaud C , Richard P , Vermersch AI , Gold F
Published: June 2009

Aim:  Hydroxychloroquine therapy during pregnancy is thought to be safe for foetuses. Normal visual function has been showed on clinical grounds in infants exposed in utero to hydroxychloroquine, but there are few visual neurophysiological data. Our study was designed to assess retina and visual pathways using electroretinogram and visual evoked potentials in a series of infants born to mothers treated by hydroxychloroquine for connective tissue diseases.

Methods:  Twenty‐one infants (3–7 months of age) were consecutively examined between June 2002 and May 2007. Full‐field electroretinogram was recorded by contact lens electrodes and visual evoked potentials were recorded by occipital surface electrodes using flash stimulation in mesopic condition. Analysis was focused on the amplitudes and latencies of the a‐ and b‐waves of electroretinogram and the latency of the P100 component of visual evoked potentials.

Results:  Electroretinogram abnormalities were detected in six infants, associated with delayed visual evoked potentials in four of them.

Conclusion:  Early electroretinogram and visual evoked potentials testing evidenced neurophysiological visual disturbances in a subset of infants born to mothers treated by hydroxychloroquine. Systematic clinical and neurophysiological vision testing during childhood is needed to detect possible consequences of antenatal exposure to hydroxychloroquine.
What Do Corporate Default Rules and Menus Do? An Empirical Examination
Authors: Listokin Yair
Published: June 2009

Much of corporate law consists of nonmandatory statutes. Although scholars have examined the effect of nonbinding corporate law from a theoretical perspective, only inconclusive event studies explore the real‐world impact of these laws. This article empirically examines the impact of nonmandatory state anti‐takeover statutes. Several conclusions emerge. Despite its nonbinding nature, corporate law makes an enormous difference in outcomes, contradicting those who claim that corporate law is trivial. Two types of nonmandatory corporate laws have particularly important effects. Corporate default laws that favor management are considerably less likely to be changed by companies than default laws favoring investors, supporting those who believe that corporate default laws can ameliorate asymmetries in incentives or bargaining power between managers and investors. Corporate “menu” laws—opt‐in laws that are drafted by the state but do not apply as default rules—also facilitate the use of some provisions, supporting those who believe that nonmandatory corporate law reduces transaction costs, such as the cost of updating corporate charters to reflect developments in the economy.
Universal Health Insurance and the Effect of Cost Containment on Mortality Rates: Strokes and Heart Attacks in Japan
Authors: Ramseyer J. Mark
Published: June 2009

For more than four decades, Japan has offered universal health insurance. Despite the demand subsidy entailed, it has kept costs low by regulatorily capping the amounts it pays doctors, particularly for the most modern and sophisticated procedures. Facing subsidized demand but stringently capped prices on complex procedures, Japanese physicians have had little incentive to invest in specialized expertise. Instead, they have invested in small private clinics and hospitals. The resulting proliferation of primitive clinics and hospitals has cut both the number of complex modern medical procedures performed, and the number of hospitals with any substantial experience in those procedures. With a quarter of the heart disease in the United States, Japan performs less than 3 percent as many coronary bypass operations and less than 6 percent as many angioplasties. Of the 855 cities and regions in Japan, 77 percent lack any hospital with substantial experience in the sophisticated modern treatment (defined below) of cerebrovascular disease, and 89 percent lack much experience in angioplasties. In this article, I estimate one of the costs of this regulatorily‐driven lack of expertise. Toward that end, I combine mortality data from 855 cities with information on local hospital expertise and local demographic composition. In the typical city, I find that the addition of one hospital with substantial experience in modern stroke treatment would cut annual stroke mortality by 7 to 16 deaths. The addition of one hospital with substantial experience in angioplasties would cut the annual deaths from heart attacks in the city by over 19.
Shareholder Protection and Stock Market Development: An Empirical Test of the Legal Origins Hypothesis
Authors: Armour John , Deakin Simon , Sarkar Prabirjit , Siems Mathias , Singh Ajit
Published: June 2009

Using a panel data set covering a range of developed and developing countries, we show that common‐law systems were more protective of shareholder interests than civil‐law ones in the period 1995–2005. However, civilian systems were catching up, suggesting that legal origin was not much of an obstacle to formal convergence in shareholder protection law. We find no evidence of a positive impact of these legal changes on stock market development. Possible explanations are that laws have been overly protective of shareholders and that transplanted laws have not worked well in contexts for which they were not suited.
Judicial Independence and Party Politics in the Kelsenian Constitutional Courts: The Case of Portugal
Authors: Amaral‐Garcia Sofia , Garoupa Nuno , Grembi Veronica
Published: June 2009

In this article we test to what extent Kelsenian‐type constitutional judges are independent from political parties by studying the Portuguese constitutional court. The results yield three main conclusions. First, constitutional judges in Portugal are quite sensitive to their political affiliations and their political party's presence in government when voting. Second, peer pressure is very relevant. Third, the 1997 reform enacted to increase judicial independence has had no robust statistically significant effect.
Moral Judgment and Moral Heuristics in Breach of Contract
Authors: Wilkinson‐Ryan Tess , Baron Jonathan
Published: June 2009

Most people think that breaking a promise is immoral, and that a breach of contract is a kind of broken promise. However, the law does not explicitly recognize the moral context of breach of contract. Using a series of web‐based questionnaires, we asked subjects to read breach of contract cases and answer questions about the legal, financial, and moral implications of each case. Our results suggest that people are quite sensitive to the moral dimensions of a breach of contract, especially the perceived intentions of the breacher. In the first study, we framed the motivation for a contractor's breach as either the chance to make more money or the chance to avoid losing money. Subjects were more punitive when the motivation appeared to be greed (breach to gain) than when the motivation appeared to be fear (breach to avoid loss). In the second study, we manipulated the timing of the negotiation over damages, comparing cases in which the promisor asks to negotiate damages before definitively breaching (as in a liquidated damages clause) with cases in which the breach has already occurred. We predicted that once the contract is breached, the moral violation becomes very salient, and we found that subjects were more punitive when setting damages ex post than ex ante. Finally, results from the third study suggest that subjects believe that intentionally breaking a contractual promise is a punishable moral harm in itself. When presented with identical losses, one from an intentional breach of contract and the other from a negligent tort, subjects were more punitive toward the breacher than the negligent tortfeasor. They treated willful breach as an intentional harm.
Reproduction of Byrsonima sericea (Malpighiaceae) in Restinga Fragmented Habitats in Southeastern Brazil
Authors: Dunley Bernardo S. , Freitas Leandro , Galetto Leonardo
Published: June 2009

Habitat fragmentation may affect the reproductive success of plant populations in many different ways. Thus, negative, neutral, or positive plant responses can be observed, according to the balance of the different interactions. Variables related to mutualistic and antagonistic interactions (pollinator activity and gall occurrence, respectively) were measured on Byrsonima sericea populations of a fragmented seashore area (restinga) in southeastern Brazil. Pollinator visits to the oil‐bearing flowers, insect gall occurrence on stems and inflorescences, and fruit set of B. sericea were compared between three small (up to 0.3 ha) and three large (14.0–99.0 ha) fragments. MANOVA showed differences between fragment classes. Nevertheless, a posteriori univariate ANOVA showed that the pollinator visit frequency was more than twofold higher in small fragments, and that gall occurrence and fruit set did not show significant differences between small and large fragments. These results suggest that the habitat fragmentation does not affect the female reproductive success of B. sericea in the studied restinga areas because resource availability seems to be a more important factor for fruit set than pollen limitation due to pollination failure. This is the first work assessing the effects of habitat fragmentation in restinga areas, which are intensely impacted by urbanization, so that no generalization about the fragmentation consequences can still be made for this ecosystem.
Constitutional Interpretation: Originalism
Authors: Goldsworthy Jeffrey
Published: June 2009

Constitutional interpretation is problematic because it can be difficult to distinguish legitimate interpretation from illegitimate change. The distinction depends largely on what a constitution is. A constitution, like any other law, necessarily has a meaning, which pre‐exists judicial interpretation: it is not a set of meaningless marks on paper. Any plausible constitutional theory must offer an account of the nature of that meaning. In doing so, it must address two main questions. The first is whether the meaning of the constitution is given solely by its words, or also by additional evidence of underlying intentions, purposes or values. The second question is whether, in either case, its meaning is determined by the original meanings, intentions, purposes or values of the founding generation, or by contemporary meanings, intentions, purposes or values. This question divides so‐called ‘originalists’ from ‘non‐originalists’. This article discusses all these alternatives, and the main arguments for and against them. It is subtitled ‘Originalism’ because it defends a moderate version of that position; however, it is argued that this is equivalent to a moderate version of non‐originalism.
Forearm and leg amino acid metabolism in the basal state and during combined insulin and amino acid stimulation after a 3‐day fast
Authors: Gjedsted J. , Gormsen L. , Buhl M. , Nørrelund H. , Schmitz O. , Keiding S. , Tønnesen E. , Møller N.
Published: June 2009

Aim:  Fasting is characterized by a progressive loss of protein, but data on protein kinetics are unclear and few have studied the effects of re‐feeding. The present study was designed to test the hypothesis that a combined infusion of insulin and amino acids after fasting would induce compensatory increases in protein synthesis and reductions in protein breakdown at the whole body level and in muscle.

Methods:  We included 10 healthy male volunteers and studied them twice: (1) in the post‐absorptive state and (2) after 72 h of fasting. Amino acid kinetics was measured using labelled phenylalanine and tyrosine, whole body energy expenditure was assessed and urea nitrogen synthesis rates were calculated.

Results:  After fasting we observed an increase in arterial blood concentration of branched chain amino acids and a decrease in gluconeogenic amino acids (P < 0.05). Isotopically determined whole body, forearm and leg phenylalanine fluxes were unaltered apart from a 30% decrease in phenylalanine‐to‐tyrosine conversion (2.0 vs. 1.4 μmol kg−1 h−1, P < 0.01). During infusion of insulin and amino acids, amino acid concentrations increased.

Conclusion:  Our data indicate that after a 72‐h fast basal and insulin/amino acid‐stimulated regional phenylalanine fluxes in leg and forearm muscle are unaltered. During fasting concentrations of gluconeogenic amino acids decrease and hepatic and/or renal phenylalanine‐to‐tyrosine conversion decreases. Thus, as opposed to glucose and lipid metabolism, fasting does not induce insulin resistance as regards amino acid metabolism.
Evidence against a sexual dimorphism in glucose and fatty acid metabolism in skeletal muscle cultures from age‐matched men and post‐menopausal women
Authors: Rune A. , Salehzadeh F. , Szekeres F. , Kühn I. , Osler M. E. , Al‐Khalili L.
Published: June 2009

Aim:  In vivo whole body differences in glucose/lipid metabolism exist between men and women. Thus, we tested the hypothesis that intrinsic sex differences exist in skeletal muscle gene expression and glucose/lipid metabolism using cultured myotubes.

Methods:  Myotube cultures were prepared for gene expression and metabolic studies from vastus lateralis skeletal muscle biopsies obtained from age‐matched men (n = 11; 59 ± 2 years) and post‐menopausal women (n = 10; 60 ± 1 years).

Results:  mRNA expression of several genes involved in glucose and lipid metabolism was higher in skeletal muscle biopsies from female vs. male donors, but unaltered between the sexes in cultured myotubes. Basal and insulin‐stimulated glucose uptake, as well as glucose incorporation into glycogen, was similar in myotube cultures derived from male vs. female donors. In males vs. females, insulin increased glucose uptake (1.3 ± 0.1 vs. 1.5 ± 0.1‐fold respectively) and incorporation into glycogen (2.3 ± 0.3 vs. 2.0 ± 0.3‐fold respectively) to the same extent. Basal fatty acid oxidation and rate of uptake/accumulation was similar between sexes. In response to the 5′AMP‐activated protein kinase activator AICAR, lipid oxidation was increased to the same extent in myotubes established from male vs. female donors (1.6 ± 0.6 vs. 2.0 ± 0.3‐fold respectively). Moreover, the AICAR‐induced rate of uptake/accumulation was similar between sexes.

Conclusion:  Differences in metabolic parameters and gene expression profiles between age‐matched men and post‐menopausal women noted in vivo are not observed in cultured human skeletal muscle cells. Thus, the sexual dimorphism in glucose and lipid metabolism is likely a consequence of systemic whole body factors, rather than intrinsic differences in the skeletal muscle proper.
Exploring Personality with the Interpersonal Circumplex
Authors: Gurtman Michael B.
Published: June 2009

The interpersonal circumplex can serve as both companion and guide for those interested in exploring the interpersonal domain of personality. This article offers a relatively nontechnical overview of the model and its various applications in the study of personality. I begin by defining the interpersonal circumplex, its structure and in what sense it is ‘interpersonal’. As part of that, I will briefly consider how circumplex measures of personality, such as the Interpersonal Adjective Scales, are typically evaluated for fit to the model. I will next describe applications of the model for exploring both the idiographic (person‐centered) and nomothetic (variable‐centered) realms of personality. In person‐centered research, the circumplex leads to useful ways of summarizing the basic interpersonal features of a given individual. In variable‐centered research, the circumplex can help elucidate the essential interpersonal meaning of personality constructs such as traits, problems, and motives. To explain how the circumplex can help us explore personality – idiographically and nomothetically – I will draw on a variety of studies, including several recent studies that extend the model in new ways.
Once upon a Time: Explaining Cultural Differences in Episodic Specificity
Authors: Wang Qi
Published: June 2009

Research has generated converging evidence of cross‐cultural differences in episodic specificity, whereby Western children and adults exhibit greater abilities to recall specific past events and event‐specific details than their Asian counterparts. Are the cultural differences a result of methodological artifacts or the true work of ‘culture?’ This article addresses this question by critically evaluating recent cross‐cultural data. The analysis based on extant work suggests that culture shapes episodic remembering through two intrapersonal variables – self‐construal and emotion knowledge – and one interpersonal variable – parent–child reminiscing. The role of culture is discussed in a larger theoretical context pertaining to human memory and cognition and future directions are suggested.
MEASURING INFLATION CREDIBILITY: RESULTS OF A FIRST REPRESENTATIVE SOUTH AFRICAN SAMPLE
Authors: Rossouw Jannie , Padayachee Vishnu
Published: June 2009

This study reports the measurement of inflation credibility of a representative sample of the South African population in terms of an inflation credibility barometer. The barometer is an instrument measuring the degree of acceptance of the accuracy of historic inflation figures. These research results serve as a benchmark for South Africa, as similar measurement of a representative sample has not been undertaken before. The sampling results show little public understanding of the rate of inflation and its measurement of average price increases experienced by an average household. As generally accepted international benchmarks for successful central‐bank communication strategies do not exist, the application of the methodology reported in this paper can improve the effectiveness of central bank communication aimed at improving the general knowledge about inflation.
AIDS, Citizenship and Global Funding: A Gambian Case Study
Authors: Cassidy Rebecca , Leach Melissa
Published: June 2009

Making sense of an HIV‐positive diagnosis is often a struggle. Across Africa this is mediated by a new globalism in public health; the last decade has seen an array of new international initiatives and funding mechanisms. These dimensions of governance exemplify, in the health sector, an intensified move away from forms of authority based on the pre‐eminence of nation states in global arenas, towards an array of new arrangements including global public‐private‐philanthropic partnerships. This Gambian case study unpicks the picture of an emergent ‘therapeutic citizenship’(Nguyen 2005) in this context – of condom demonstrations and public disclosures – looking to the strands of authority and governance linked to an epistemic structure initiated by the Global Fund, but that works through a complex web of other organisations and agencies. This suggests that in Gambia in the period up to the end of 2006, the focus of this paper, a local‐global axis which constructed HIV related problems, solutions and related notions of identity and political affiliation had come into being. For people living with HIV in the Gambia, making claims based on their status in this field has been problematic, and their ability to shape proactively what goes on and assert their felt needs often rather limited.
Possible contribution of the non‐proteolytic activation of prorenin to the development of insulin resistance in fructose‐fed rats
Authors: Nagai Yukiko , Ichihara Atsuhiro , Nakano Daisuke , Kimura Shoji , Pelisch Nicolas , Fujisawa Yoshihide , Hitomi Hirofumi , Hosomi Naohisa , Kiyomoto Hideyasu , Kohno Masakazu , Ito Hiroshi , Nishiyama Akira
Published: June 2009

Recent studies have shown that blocking non‐proteolytically activated prorenin with a decoy peptide for the handle region of the prorenin prosegment (HRP) inhibits the development of microvascular complications in diabetic animals. In the present study, we investigated whether non‐proteolytic activation of prorenin contributes to the development of fructose‐induced insulin resistance. Rats were fed a standard diet (n= 10), a 60% high fructose diet (n= 16), or a high fructose diet + HRP (0.1 mg kg−1 day−1, n= 16) for 10 weeks. Fructose‐fed rats showed higher systolic blood pressure (SBP), fasting plasma triglycerides, total cholesterol and insulin levels; which, except for SBP, were suppressed by HRP. The responses of plasma glucose and insulin levels to oral glucose loading were significantly greater in fructose‐fed rats than in standard diet‐fed rats. The HRP normalized the enhanced responses of plasma glucose and insulin levels that were observed in fructose‐fed rats. Moreover, HRP suppressed the enhanced prorenin activation and angiotensin II formation in the soleus muscle of fructose‐fed rats. These data suggest that local angiotensin II generation in skeletal muscle, induced by non‐proteolytic activation of prorenin, contributes to the development of insulin resistance induced by a high fructose diet.
The effects of antioxidants on microvascular oxygenation and blood flow in skeletal muscle of young rats
Authors: Copp Steven W. , Ferreira Leonardo F. , Herspring Kyle F. , Hirai Daniel M. , Snyder Brian S. , Poole David C. , Musch Timothy I.
Published: June 2009

Alterations of skeletal muscle redox state via antioxidant supplementation have the potential to impact contractile function and vascular smooth muscle tone. The effects of antioxidants on the regulation of muscle O2 delivery–O2 utilization (
) matching (which sets the microvascular partial pressure of O2;
) in young healthy muscle are not known. Therefore, the purpose of this study was to test the effects of acute antioxidant supplementation on rat spinotrapezius muscle force production, blood flow,
and
(phosphorescence quenching). Anaesthetized male Fischer 344 × Brown Norway rats (6–8 months old) had their right spinotrapezius muscles either exposed for measurement of blood flow and
(n= 13) or exteriorized for measurement of muscle force production (n= 6). Electrically stimulated 1 Hz twitch contractions (∼7–9 V) were elicited for 180 s, and measurements were made before and after acute intra‐arterial antioxidant supplementation (76 mg kg−1 ascorbic acid, 52 mg kg−1 tempol) dissolved in saline and infused over 30 min. The principal effects of antioxidants were a ∼25% decrease (P < 0.05) in contracting spinotrapezius muscle force production concurrent with reductions in muscle blood flow and
at rest and during contractions (P < 0.05 for both). Antioxidant supplementation reduced the resting baseline
(before, 29.9 ± 1.2 mmHg; after, 25.6 ± 1.3 mmHg; P < 0.05), and this magnitude of depression was sustained throughout the rest‐to‐exercise transition (steady‐state value before, 16.4 ± 0.7 mmHg; after, 13.6 ± 0.9 mmHg; P < 0.05). In addition, the time constant of the
decrease was reduced after antioxidant supplementation (before, 23.4 ± 4.3 s; after, 15.6 ± 2.7 s; P < 0.05). These results demonstrate that antioxidant supplementation significantly impacts the control of
in young rats at rest and during contractions.
Predictive Analytical Thermal Stress Modeling in Electronics and Photonics
Authors: Suhir E.
Published: June 2009

We discuss the role and the attributes of, as well as the state-of-the-art and some major findings in, the area of predictive analytical (“mathematical”) thermal stress modeling in electronic, opto-electronic, and photonic engineering. The emphasis is on packaging assemblies and structures and on simple meaningful practical models that can be (and actually have been) used in the mechanical (“physical”) design and reliability evaluations of electronic, opto-electronic, and photonic assemblies, structures, and systems. We indicate the role, objectives, attributes, merits, and shortcomings of analytical modeling and discuss its interaction with finite-element analysis (FEA) simulations and experimental techniques. Significant attention is devoted to the physics of the addressed problems and the rationale behind the described models. The addressed topics include (1) the pioneering Timoshenko’s analysis of bimetal thermostats and its extension for bimaterial assemblies of finite size and with consideration of the role of the bonding layer of finite compliance; this situation is typical for assemblies employed in electronics and photonics; (2) thermal stresses and strains in solder joints and interconnections; (3) attributes of the “global” and “local” thermal expansion (contraction) mismatch and the interaction of the induced stresses; (4) thermal stress in assemblies adhesively bonded at the ends and in assemblies (structural elements) with a low-modulus bonding layer at the ends (for lower interfacial stresses); (5) thin film systems; (6) thermal stress induced bow and bow-free assemblies subjected to the change in temperature; (7) predicted thermal stresses in, and the bow of, plastic packages of integrated circuit devices, with an emphasis on moisture-sensitive packages; (8) thermal stress in coated optical fibers and some other photonic structures; and (9) mechanical behavior of assemblies with thermally matched components (adherends). We formulate some general design recommendations for adhesively bonded or soldered assemblies subjected to thermal loading and indicate an incentive for a wider use of probabilistic methods in physical design for reliability of “high-technology” assemblies, including those subjected to thermal loading. Finally, we briefly address the role of thermal stress modeling in composite nanomaterials and nanostructures. It is concluded that analytical modeling should be used, whenever possible, along with computer-aided simulations (FEA) and accelerated life testing, in any significant engineering effort, when there is a need to analyze and design, in a fast, inexpensive, and insightful way, a viable, reliable, and cost-effective electronic, opto-electronic, or photonic assembly, package, or system.
Elastic and Plastic Response of Perforated Metal Sheets With Different Porosity Architectures
Authors: Khatam Hamed , Chen Linfeng , Pindera Marek-Jerzy
Published: June 2009

The effects of porosity architecture and volume fraction on the homogenized elastic moduli and elastic-plastic response of perforated thin metal sheets are investigated under three fundamental loading modes using an efficient homogenization theory. Steel and aluminum sheets weakened by circular, hexagonal, square, and slotted holes arranged in square and hexagonal arrays subjected to inplane normal and shear loading are considered with porosity volume fractions in the range 0.1–0.6. Substantial variations are observed in the homogenized elastic moduli with porosity shape and array type. The differences are rooted in the stress transfer mechanism around traction-free porosities whose shape and distribution play major roles in altering the local stress fields and thus the homogenized response in the elastic-plastic domain. This response is characterized by four parameters that define different stages of micro- and macrolevel yielding. The variations in these parameters due to porosity architecture and loading direction provide useful data for design purposes under monotonic and cyclic loading.
Magnetohydrodynamic Convective Heat and Mass Transfer Flow Due to a
Rotating Disk With Thermal Diffusion Effect
Authors: Maleque Kh. Abdul
Published: June 2009

Considering the importance of mass transfer in a magnetohydrodynamic (MHD) convective flow, a numerical solution is obtained for a steady three-dimensional MHD convective mass transfer flow in an incompressible fluid due to a rotating disk with thermal diffusion. The governing partial differential equations of the MHD convective mass transfer flow are reduced to nonlinear ordinary differential equations by introducing suitable similarity transformations. The nonlinear similarity equations are then solved numerically by Nachtsheim–Swigert iteration technique. The results of the numerical solution are then presented graphically in the form of velocity, temperature, and concentration profiles. The corresponding skin-friction coefficients, the Nusselt number, and the Sherwood number are also calculated and displayed in tables showing the effects of various parameters on them. A good comparison between the present numerical predictions and the previously published data (Sparrow, and Gregg, 1959, “Heat Transfer From a Rotating Disk to Fluids of Any Prandtl Number,” ASME J. Heat Transfer, 8, pp. 249–251; Benton, 1966, “On the Flow Due to a Rotating Disc,” J. Fluid Mech., 24, pp. 781–800) has been achieved.
Full-Field Flow Measurements and Heat Transfer of a Compact Jet Impingement Array With Local Extraction of Spent Fluid
Authors: Onstad Andrew J. , Elkins Christopher J. , Moffat Robert J. , Eaton John K.
Published: June 2009

Jet impingement cooling is widely used due to the very high heat transfer coefficients that are attainable. Both single and multiple jet systems can be used, however, multiple jet systems offer higher and more uniform heat transfer. A staggered array of 8.46 mm diameter impingement jets with jet-to-jet spacing of 2.34 D was examined where the spent fluid is extracted through one of six 7.36 mm diameter extraction holes regularly located around each jet. The array had an extraction area ratio (Ae/Ajet) of 2.23 locally and was tested with a jet-to-target spacing (H/D) of 1.18 jet diameters. Magnetic resonance velocimetry was used to both quantify and visualize the three dimensional flow field inside the cooling cavity at jet Reynolds numbers of 2600 and 5300. The spatially averaged velocity measurements showed a smooth transition is possible from the impingement jet to the extraction hole without the presence of large vortical structures. Mean Nusselt number measurements were made over a jet Reynolds number range of 2000–10,000. Nusselt numbers near 75 were measured at the highest Reynolds number with an estimated uncertainty of 7%. Large mass flow rate per unit heat transfer area ratios were required because of the small jet-to-jet spacing.
Natural Convection Heat Transfer From Horizontal Rectangular Inverted Notched Fin Arrays
Authors: Suryawanshi Sanjeev D. , Sane Narayan K.
Published: June 2009

The variables for natural convection cooling with the help of finned surfaces are orientation and geometry. In lengthwise short array (L/H∼5), where single chimney flow pattern is present, a stagnant zone is created at the central bottom portion of fin array channel and hence it does not contribute much in heat dissipation. Hence it is removed in the form of inverted notch at the central bottom portion of fin to modify its geometry for enhancement of heat transfer. An experimental setup is developed for studying the investigation on normal and inverted notched fin arrays (INFAs). Fin spacing, heater input, and percentage of area removed in the form of inverted notch are the parameters. For few spacing, it is verified by computational fluid dynamics analysis (Course Notes on Introduction to Commercial CFD of Tridiagonal Solutions, Pune), and the results are well matching. It is found that the average heat transfer coefficient for INFAs is nearly 30–40% higher as compared with normal array.
Experimental Determination and Modeling of the Radiative Properties of Silica Nanoporous Matrices
Authors: Lallich Sylvain , Enguehard Franck , Baillis Dominique
Published: June 2009

Superinsulating materials are currently of interest because the heating and cooling of houses and offices are responsible for an important part of CO2 emissions. In this study, we aim at modeling the radiative transfer in nanoporous silica matrices that are the principal components of nanoporous superinsulating materials. We first elaborate samples from different pyrogenic amorphous silica powders that slightly differ one from another in terms of specific surface, nanoparticle diameter, and composition. The various samples are optically characterized using two spectrometers operating on the wavelength range (250 nm; 20μm). Once the hemispherical transmittance and reflectance spectra are measured, we deduce the radiative properties using a parameter identification technique. Then, as the considered media are made of packed quasispherical nanoparticles, we try to model their radiative properties using the original Mie theory. To obtain a good agreement between experiment and theory on a large part of the wavelength range, we have to consider scatterers that are up to five times larger than the primary nanoparticles; this is attributed to the fact that the scatterers are not the nanoparticles but aggregates of nanoparticles that are constituted during the fabrication process of the powders. Nevertheless, in the small wavelength range (λ smaller than 1μm), we can never get a satisfactory agreement using the Mie theory. This disagreement is attributed to the fact that the original Mie theory does not take into account the nanostructure of the aggregates. So we have developed a code based on the discrete dipole approximation that improves the modeling results in the small wavelength range, basing our computations on aggregates generated using the diffusion-limited cluster-cluster aggregation algorithm in order to ensure a fractal dimension close to what is usually found with aggregates of silica nanoparticles.
An Experimental Investigation of the Cold Mass Fraction, Nozzle Number, and Inlet Pressure Effects on Performance of Counter Flow Vortex Tube
Authors: Kırmacı Volkan , Uluer Onuralp
Published: June 2009

This paper discusses the experimental investigation of vortex tube performance as it relates to cold mass fraction, inlet pressure, and nozzle number. The orifices have been made of the polyamide plastic material. Five different orifices, each with two, three, four, five and six nozzles, respectively, were manufactured and used during the test. The experiments have been conducted with each one of those orifices shown above, and the performance of the vortex tube has been tested with air inlet pressures varying from 150 kPa to 700 kPa with 50 kPa increments and the cold mass fractions of 0.5–0.7 with 0.02 increments. The energy separation has been investigated by use of the experimentally obtained data. The results of the experimental study have shown that the inlet pressure was the most effective parameter on heating and the cooling performance of the vortex tube. This occurs due to the higher angular velocities and angular momentum conservation inside the vortex tube. The higher the inlet pressure produces, the higher the angular velocity difference between the center flow and the peripheral flow in the tube. Furthermore, the higher velocity also means a higher frictional heat formation between the wall and the flow at the wall surface of the tube. This results in lower cold outlet temperatures and higher hot outlet temperatures.
Characterization and Pool Boiling Heat Transfer Studies of Nanofluids
Authors: Kathiravan R. , Kumar Ravi , Gupta Akhilesh , Chandra Ramesh
Published: June 2009

Copper nanoparticles with an average size of 10 nm are prepared by the sputtering method and are characterized using different techniques, viz., X-ray diffraction spectrum, atomic force microscopy, and transmission electron microscopy. The pool boiling heat transfer characteristics of 0.25%, 0.5%, and 1.0% by weight concentrations of copper nanoparticles dispersed in distilled water and in distilled water with 9.0 wt % of sodium dodecyl sulfate (SDS) are studied. Also the data for the boiling of pure distilled water and water with SDS are acquired. The above data are obtained using commercial seamless stainless steel tube heater with an outer diameter of 9.0 mm and an average surface roughness of 1.09 μm. The experimental results concluded that (i) critical heat flux (CHF) obtained in water with surfactant nanofluids gives nearly one-third of the CHF obtained by copper-water nanofluids, (ii) pool boiling heat transfer coefficient decreases with the increase in the concentration of nanoparticles in water base fluids, and (iii) heat transfer coefficient increases with the addition of 9.0% surfactant in water. Further addition of nanoparticles in this mixture reduces the heat transfer coefficient. (iv) CHF increases nearly 50% with an increase in concentration of nanoparticles in the water as base fluid and nearly 60% in the water with surfactant as base fluid.
Heat Transfer and Thermodynamic Analyses of Some Typical Encapsulated Ice Geometries During Discharging Process
Authors: MacPhee David , Dincer Ibrahim
Published: June 2009

This study deals with the process of melting in some typical encapsulated ice thermal energy storage (TES) geometries. Cylindrical and slab capsules are compared with spherical capsules when subjected to a flowing heat transfer fluid (HTF). The effect of inlet HTF temperature and flow rate as well as the reference temperatures are investigated, and the resulting solidification and melting times, energy efficiencies, and exergy efficiencies are documented. Using ANSYS GAMBIT and FLUENT 6.0 softwares, all geometries are created, and the appropriate boundary and initial conditions are selected for the finite volume solver to proceed. Sufficient flow parameters are monitored during transient solutions to enable the calculation of all energy and exergy efficiencies. The energetically most efficient geometric scenario is obtained for the slab geometry, while the spherical geometry exergetically achieves the highest efficiencies. The difference between the two results is mainly through the accounting of entropy generation and exergy destroyed, and the largest mode of thermal exergy loss is found to be through entropy generation resulting from heat transfer accompanying phase change, although viscous dissipation is included in the analysis. All efficiency values tend to increase with decreasing HTF flow rate, but exergetically the best scenario appears to be for the spherical capsules with low inlet HTF temperature. Energy efficiency values are all well over 99%, while the exergy efficiency values range from around 72% to 84%, respectively. The results indicate that energy analyses, while able to predict viscous dissipation losses effectively, cannot correctly quantify losses inherent in cold TES systems, and in some instances predict higher than normal efficiencies and inaccurate optimal parameters when compared with exergy analyses.
Cooling Rate and Size Effect on the Microstructure and Mechanical Properties of AlCoCrFeNi High Entropy Alloy
Authors: Wang F. J. , Zhang Y. , Chen G. L. , Davies H. A.
Published: June 2009

High entropy alloys are usually defined as the kind of alloys with at least five principle components, each component has the equi-atomic ratio or near equi-atomic ratio, and the high entropy alloys can have very high entropy of mixing, forming simple solid solution rather than many complex intermediate phases. In this paper, the size effects on the microstructure and mechanical behaviors of a high entropy alloy of AlCoCrFeNi was studied by preparing as-cast rod samples with different diameters. The alloy independent of cast diameter samples has the same phase of body centered cubic solid solution. With decreasing casting diameter, both the strength and the plasticity are increased slightly.
Novel Two-Dimensional Transient Heat Conduction Calculation in a Cooled Rotor: Ventilation Preheating—Blow-Down Flux
Authors: Solano J. P. , Paniagua G.
Published: June 2009

This contribution presents an alternative to classical data reduction techniques to measure the heat transfer using thin-film gauges. A finite-element model of the two-dimensional unsteady heat conduction equation is solved in the cross-sectional area of a metallic airfoil bounded with a polyamide sheet on which thermal sensors are deposited. This novel methodology allows capturing all 2D heat conduction effects that are irremediably neglected with the 1D data reduction technique. The application of this technique in a compression tube facility allows an exact evaluation of the initial wall heat flux into cooled rotor blades. During the spinning-up period, the rotor is spun up to nearly its nominal speed (from 0 rpm to 6200 rpm) resulting in preheating due to drag losses. The long duration of this experiment (∼450 s) and the magnitude of the wall temperature increase result in significant 2D conduction effects that are not accounted for using the 1D approach. In addition, short-duration experiments confirm the existence of 2D effects at smaller time scales (∼0.5 s), as well as the influence of the initial nonuniform temperature distribution in the rotor blade. The resulting flux with such an initial condition appears to be the superposition of the wall heat flux at the end of the spinning up before the test and the flux due to the blow-down itself.
Design for Manufacturing of Sculptured Surfaces: A Computational Platform
Authors: Barari Ahmad , ElMaraghy Hoda A. , ElMaraghy Waguih H.
Published: June 2009

This paper presents a computer aided design for machining (DFMc) platform that enables designers to customize the design for the available machine tools and to estimate the effect of design decisions on the accuracy of the final machined products, particularly those containing sculptured surfaces. The platform contains two modules to model and simulate the actual machined surface and to evaluate the resulting minimum deviation zone compared to the desired geometry. In the first module, based on the configuration of the available machine tool and the limitations imposed by its inherent errors, the machined surface is simulated and presented as a nonuniform rational B-spline (NURBS) surface. In the second module, the minimum deviation zone between the actual and the nominal NURBS surfaces is evaluated when the developed method to do this task efficiently improves the convergence of the resulting optimization process. Utilizing this platform, two different applications are developed; design tolerance allocation based on the minimum deviation zone of the machined surface and adaptation of the nominal design to compensate for the effect of machining errors. Employing these applications during the design stage improves the acceptance rate of the produced parts and reduces the rate of scrap and rework. The DFMc platform and its presented applications can be implemented in any integrated computer aided design/computer aided manufacturing (CAD/CAM) system. The presented methods can be applied to any type of input geometries and are particularly efficient for design and manufacturing of precise components with complex surfaces. Products in this group, such as dies and tools, medical instruments, and biomedical implants, mostly have critical and important functionalities that demand very careful design and manufacturing decisions.