bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Consequences of the Internet for Adolescents
Authors: Valkenburg Patti M. , Peter Jochen
Published: February 2009

Adolescents are currently the defining users of the Internet. They spend more time online than adults do, and they use the Internet for social interaction more often than adults do. This article discusses the state of the literature on the consequences of online communication technologies (e.g., instant messaging) for adolescents' social connectedness and well-being. Whereas several studies in the 1990s suggested that Internet use is detrimental, recent studies tend to report opposite effects. We first explain why the results of more recent studies diverge from those of earlier studies. Then, we discuss a viable hypothesis to explain the recent findings: the Internet-enhanced self-disclosure hypothesis. Finally, we discuss some contingent factors that may deserve special attention in future research.
Functional Neuroimaging Insights Into the Development of Skilled Reading
Authors: Schlaggar Bradley L. , Church Jessica A.
Published: February 2009

Typically developing children require years of overt training and practice to learn to read with skill. The relatively recent advent of functional neuroimaging methods amenable to the study of children has provided insight into the neurobiological underpinnings of skilled reading development. In this brief review, we discuss how neuroimaging during reading-related tasks has revealed that, when adult and child skilled readers perform identical reading-related tasks with comparable levels of performance, these groups show similar but nonidentical patterns of regional brain activity. Children activate some neural regions that adults do not activate (or activate less), and vice versa. The activity patterns in these regions transition to mature levels with increased proficiency and maturity. The dynamic nature of the reading brain as the child matures is thought to be a demonstration of both the inherent flexibility and the increasing efficiency of brain processing over development.
Stability and Change in Personality Disorder
Authors: Clark Lee Anna
Published: February 2009

The standard view of personality disorder is that it is a maladaptive expression of personality traits, which are relatively stable and unchanging. Thus, personality disorder has been considered to have its roots in childhood and adolescence, to persist in adulthood, and to be difficult to change. However, recent research has challenged this view, revealing that personality continues to change, albeit more slowly, well into adulthood, and that the maladaptive manifestations of personality disorder are much less stable than previously believed. These research findings are described, and factors that influence stability and change in personality disorder are discussed. The emerging view of personality disorder has important implications for diagnosis, assessment, and treatment of personality pathology.
Person Perception and Personality Pathology
Authors: Oltmanns Thomas F. , Turkheimer Eric
Published: February 2009

Studies of person perception (people's impressions and beliefs about others) have developed important concepts and methods that can be used to help improve the assessment of personality disorders. They may also inspire advances in our knowledge of the nature and origins of these conditions. Information collected from peers and other types of informants is reliable and provides a perspective that often differs substantially from that obtained using questionnaires and interviews. For some purposes, this information is quite useful. Much remains to be learned about the incremental validity (and potential biases) associated with data from various kinds of informants.
When Walking Makes Perception Better
Authors: Durgin Frank H.
Published: February 2009

When we move, the visual world moves toward us. That is, self-motion normally produces visual signals (flow) that tell us about our own motion. But these signals are distorted by our motion: Visual flow actually appears slower while we are moving than it does when we are stationary and our surroundings move past us. Although for many years these kinds of distortions have been interpreted as a suppression of flow to promote the perception of a stable world, current research has shown that these shifts in perceived visual speed may have an important function in measuring our own self-motion. Specifically, by slowing down the apparent rate of visual flow during self-motion, our visual system is able to perceive differences between actual and expected flow more precisely. This is useful in the control of action.
Infants' Grasp of Others' Intentions
Authors: Woodward Amanda L.
Published: February 2009

The perception of others as intentional agents is fundamental to human experience and foundational to development. Recent research reveals that this cornerstone of social perception has its roots early in infancy, and that it is influenced by the universal, early-emerging human experience of engaging in goal-directed action. Infants' own action capabilities correlate with their emerging tendency to view others' actions as organized by goals. Moreover, interventions that facilitate new goal-directed actions alter infants' perception of those same actions in others. These effects seem to depend on the first-person aspects of infants' experience. These findings open new questions about how doing leads to knowing in the social domain.
Who I Am Depends on How I Feel
Authors: Ashton-James Claire E. , Maddux William W. , Galinsky Adam D. , Chartrand Tanya L.
Published: February 2009

We present a novel role of affect in the expression of culture. Four experiments tested whether individuals' affective states moderate the expression of culturally normative cognitions and behaviors. We consistently found that value expressions, self-construals, and behaviors were less consistent with cultural norms when individuals were experiencing positive rather than negative affect. Positive affect allowed individuals to explore novel thoughts and behaviors that departed from cultural constraints, whereas negative affect bound people to cultural norms. As a result, when Westerners experienced positive rather than negative affect, they valued self-expression less, showed a greater preference for objects that reflected conformity, viewed the self in more interdependent terms, and sat closer to other people. East Asians showed the reverse pattern for each of these measures, valuing and expressing individuality and independence more when experiencing positive than when experiencing negative affect. The results suggest that affect serves an important functional purpose of attuning individuals more or less closely to their cultural heritage.
The Price of Pain and the Value of Suffering
Authors: Vlaev Ivo , Seymour Ben , Dolan Raymond J. , Chater Nick
Published: February 2009

Estimating the financial value of pain informs issues as diverse as the market price of analgesics, the cost-effectiveness of clinical treatments, compensation for injury, and the response to public hazards. Such valuations are assumed to reflect a stable trade-off between relief of discomfort and money. Here, using an auction-based health-market experiment, we show that the price people pay for relief of pain is strongly determined by the local context of the market, that is, by recent intensities of pain or immediately disposable income (but not overall wealth). The absence of a stable valuation metric suggests that the dynamic behavior of health markets is not predictable from the static behavior of individuals. We conclude that the results follow the dynamics of habit-formation models of economic theory, and thus, this study provides the first scientific basis for this type of preference modeling.
Temporary Stabilizations, Sudden Stops, and Asset Prices
Authors: Singh Rajesh , Subramanian Chetan
Published: February 2009

The authors study a temporary exchange‐rate based stabilization plan in which agents face a sudden stop of capital inflows. The model generates a rising path of real interest rates in advance of the exchange rate collapse. This generates a time‐dependent non‐monotonic path of required premium on domestic assets. The model‐generated asset price dynamics closely mimic their empirical counterpart, as witnessed during recent collapses of exchange‐rate based stabilization plans. The model also reproduces consumption and foreign reserve dynamics that closely mimic the data.
International Trade in Hazardous Waste
Authors: Baggs Jen
Published: February 2009

This paper combines a gravity model with country characteristics to examine trade in hazardous waste. A significant pollution haven effect is observed as rising per capita income reduces the amount of hazardous waste countries’ import. However, this effect is outweighed by high‐income countries’ relative capital abundance, and by rising GDP creating larger increases in disposal capacity than waste production. Simulating the volume and direction of hazardous waste trade in the absence of distance costs, leads to a 153% increase in waste traded, and a larger increase in shipments from non‐OECD countries to OECD members than from the OECD to nonmembers.
Nonlinear Adjustment in Law of One Price Deviations and Physical Characteristics of Goods
Authors: Berka Martin
Published: February 2009

At a level of individual goods, heterogeneity of marginal transaction costs, proxied by price‐to‐weight ratios and stowage factors, explains a large part of the variation in thresholds of no‐adjustment and conditional half‐lives of law of one price deviations. Prices of heavier (more voluminous) goods deviate further before becoming mean‐reverting. Moreover, after becoming mean‐reverting, prices of heavier goods converge more slowly. Together with measures of pricing power, market size, distance, and exchange rate volatility, these factors explain up to 43% of variation in no‐adjustment threshold estimates across 52 goods in US–Canada post‐Bretton Woods monthly CPI data and are robust in a broader five‐country dataset. They open two avenues for the importance of marginal transaction costs in accounting for real exchange rate persistence: through (a) generating persistence in individual real exchange rate components, and (b) accentuating it by the aggregation of heterogeneous components (“aggregation bias” ofImbs et al., 2005a).
NAFTA and the Realignment of Textile and Apparel Trade: Trade Creation or Trade Diversion?*
Authors: Datta Anusua , Kouliavtsev Mikhail
Published: February 2009

A modified version of the partial‐equilibrium gravity model, originally proposed by Fukao et al. (2003), is employed to investigate the changing pattern of US textile trade. We use US Bilateral Manufacturing Imports and Exports data for 1989–2001 to assess the impact of labor wages, tariffs, and exchange rates on the composition of US textile imports before and after the creation of NAFTA. The analysis is performed at the SIC two‐digit industry level and the more disaggregated four‐digit sector level. We find little evidence of trade diversion in textiles frequently attributed to NAFTA, while trade creation is clearly present. Furthermore, lower wages in some textile‐exporting countries (e.g. countries in Asia) do not appear to significantly increase these countries' shares of US textile imports at the expense of other trading partners. However, variations in currency exchange rates and tariffs have substantial effects on the composition of US imports.
The Economic Impact of Medical Migration: A Receiving Country's Perspective
Authors: Rutten Martine
Published: February 2009

This paper seeks to determine the macroeconomic impacts of migration of skilled medical personnel from a receiving country's perspective. The resource allocation issues are explored in theory, by developing an extension of the Rybczynski theorem in a low‐dimension Heckscher–Ohlin framework, and empirically, by developing a static CGE model for the UK with an extended health sector component. Using simple diagrams, an expansion of the health sector by recruiting immigrant skilled workers in certain cases is shown to compare favorably to the long‐term (short‐term) alternative of using domestic (unskilled) workers. From a formal analysis, changes in nonhealth outputs are shown to depend on factor‐bias and scale effects. The net effects generally are indeterminate. The main finding from the applied model is that importing foreign doctors and nurses into the UK yields higher overall welfare gains than a generic increase in the NHS budget. Welfare gains rise in case of wage protection.
Exchange Rate Passthrough to Export Prices: Assessing Cross‐Country Evidence*
Authors: Vigfusson Robert J. , Sheets Nathan , Gagnon Joseph
Published: February 2009

A growing empirical literature reports evidence of a decline in exchange rate passthrough to import prices in a number of industrial countries. Our paper complements this literature by examining passthrough from the other side of the transaction; that is, we assess the exchange rate sensitivity of export prices (denominated in the exporter's currency). We find that the prices charged on exports to the United States are more responsive to the exchange rate than are export prices to other destinations, which is consistent with results in the literature that import price passthrough in the US market is relatively low. In addition, the exchange rate sensitivity of export prices over time has been significantly affected by country‐ and region‐specific factors, including the Asian financial crisis (for emerging Asia), deepening integration with the United States (for Canada), and the effects of the 1992 ERM crisis (for the United Kingdom).
THE BLANK FACE OF LOVE: THE POSSIBILITY OF GOODNESS IN THE LITERARY AND PHILOSOPHICAL WORK OF IRIS MURDOCH1
Authors: GOODYER JENNIFER SPENCER
Published: February 2009

This article explores the value of Iris Murdoch's metaphysical ethics for the theologian. Although, in many ways, Murdoch does appeal to the theologian, a subtle form of nihilism underlies her thought insofar as human goodness—in the form of loving attention—is only possible once the individual has overcome his/her ego by staring into the void and accepting the ultimate meaninglessness of reality. As this article demonstrates, Murdoch's replacement of transcendence with void rules out any form of real love or human goodness: only a dualistic exchange of gazes remains possible. Real, selfless love is only possible when the ego understands itself in the context of theological transcendence.
THEOLOGY IN THE UNIVERSITY: ONCE MORE, WITH FEELING
Authors: KELSEY DAVID H.
Published: February 2009

Stanley Hauerwas and Gavin D'Costa develop theological arguments for inclusion of constructive theology in Universities' curricula; Andrew Shanks offers an equivalent. They share the conviction that the practice of theology cannot be separated from religious practices. Beyond that, however, their arguments scarcely intersect, in part because of differing analyses of the “secularity” that underwrites the academy's skepticism of theology as a “discipline.” Hauerwas analyses secularity theologically; Shanks urges that even secular societies exhibit “will to Honesty” (think, perhaps, “ultimate concern”) that is inherently religious and theological; D'Costa argues that central to secular liberalism is a commitment to genuine pluralism that ought to foster theologies in their particularities.
Dealing with Benchmark Revisions in Real‐Time Data: The Case of German Production and Orders Statistics*
Authors: Knetsch Thomas A. , Reimers Hans‐Eggert
Published: February 2009

Benchmark revisions in non‐stationary real‐time data may adversely affect the results of regular revision analysis and the estimates of long‐run economic relationships. Cointegration analysis can reveal the nature of vintage heterogeneity and guide the adjustment of real‐time data for benchmark revisions. Affine vintage transformation functions estimated by cointegration regressions are a flexible tool, whereas differencing and rebasing work well only under certain circumstances. Inappropriate vintage transformation may cause observed revision statistics to be affected by nuisance parameters. Using real‐time data of German industrial production and orders, the econometric techniques are exemplified and the theoretical claims are examined empirically.
Does the World Economy Swing National Elections?*
Authors: Leigh Andrew
Published: February 2009

Do voters reward national leaders who are more competent economic managers, or merely those who happen to be in power when the world economy booms? Using data from 268 democratic elections held between 1978 and 1999, I compare the effect of world growth (luck) and national growth relative to world growth (competence). Both matter, but the effect of luck is larger than the effect of competence. Voters are more likely to reward competence in countries that are richer and better educated; and there is some suggestive evidence that media penetration rates affect the returns to luck and competence.
Headache Syndromes After Acoustic Neuroma Surgery and Their Implications for Quality of Life
Authors: Schankin CJ , Gall C , Straube A
Published: February 2009

The patients of this prospective study were analysed for headache as a sequela of surgery for acoustic neuroma (AN). Thirty-two per cent (30/95) of patients complained about a persisting headache syndrome with a severity of at least 6/10 on the nominal analogue scale 6 months after surgery. The occurrence of headache was significantly correlated with the prospectively evaluated parameters preoperative headache and the number of perioperative complications. Postoperative failure to return to the preoperative level of activity was also associated with the occurrence of headache, but also with the risk of retirement after successful surgery of the AN. Headache is therefore, like postoperative ataxia, dysgeusia and probably facial paresis, an important factor for the overall outcome of patients after AN surgery. Hypacusis is not as important. The symptoms and course of each individual patient were analysed. The attempt to categorize the headaches according to the second edition of the International Classification of Headache Disorders revealed five headache syndromes, the most prevalent being tension-type-like headache (46.7%), followed by neuralgia of the occipital nerve (16.6%), trigeminal neuropathy (16.6%), neuropathy of the intermedian nerve (10.0%) and cervicogenic headache (10.0%). The respective pathophysiological mechanisms are discussed and treatment options based on the clinical picture are presented.
Does Interpretation in Psychology Differ From Interpretation in Natural Science?
Authors: MARTIN JACK , SUGARMAN JEFF
Published: February 2009

Following an initial discussion of the general nature of interpretation in contemporary psychology, and social and natural science, relevant views of Charles Taylor and Thomas Kuhn are considered in some detail. Although both Taylor and Kuhn agree that interpretation in the social or human sciences differs in some ways from interpretation in the natural sciences, they disagree about the nature and origins of such difference. Our own analysis follows, in which we consider differences in interpretation between the natural and social sciences (psychology in particular) in terms of Ian Hacking's use of Elizabeth Anscombe's conceptualization of actions as intentional acts under particular descriptions. We conclude that both Taylor and Kuhn are correct to point to differences in interpretation between the natural and social sciences. We also argue that in psychology, such interpretive differences, contra Kuhn and pro Taylor, are qualitative rather than quantitative. They arise from the nature of persons as self‐interpretive, reactive beings who act under socioculturally sanctioned, linguistic descriptions. The actions of psychological persons may display qualitative differences over time and across contexts as these descriptions, including social scientific and psychological findings and interpretations, change. In contrast, even when descriptions in natural science change, such changes do not spawn changes in the self‐interpretations and intentional actions of the focal phenomena of natural science. We also make the point that much current confusion surrounding interpretation in science arises from the unwarranted tendency of some commentators to treat interpretation as subjective, in ways that ignore the objective grounding of interpretation within regulated social practices, including scientific practices sanctioned by scientific communities.
Social Objects, Causality and Contingent Realism
Authors: WILLIAMS MALCOLM
Published: February 2009

This paper is a realist argument for the existence of “social objects”. Social objects, I argue, are the outcome states of a contingent causal process and in turn posses causal properties. This argument has consequences for what we can mean by realism and consequences for the development of a realist methodology. Realism should abandon the notion of natural necessity in favour of a view that the “real” nature of the social world is contingent and necessity is only revealed in outcome states. This, I argue, has both theoretical and methodological implications and I develop my argument through two case studies, of homelessness and ethnicity.
Morphometrics of corneal growth in chicks raised in constant light
Authors: Wahl Christina , Li Tong , Choden Tsering , Howland Howard
Published: February 2009

In this study we wish to augment our understanding of the effect of environment on corneal growth and morphology. To understand how corneal development of chicks raised in constant light differs from that of ‘normal’ eyes exposed to cyclic periods of light and dark, white Leghorn chicks were raised under either constant light (approximately 700 lux at cage top) or in 12 h light/12 h dark conditions for up to 12 weeks after hatching. To determine whether corneal expansion is uniform, some birds from each group received corneal tattoos for periodic photographic assessment. By 16 days of age, constant light corneas weighed less than light/dark regimen corneas [7.39 ± 0.35 mg (SE) vs. 8.47 mg ± 0.26 mg SE wet weight, P ≤ 0.05], and corresponding differences were seen in corneal dry weights. Spatial expansion of the corneal surface was uniform in both groups, but the rate of expansion was slower in constant light chicks [0.0327 ± 0.009 (SE) vs. 0.144 ± 0.018 (SE) mm2 day−1 for normal chicks, P ≤ 0.001]. At 1 day of age, there were 422 ± 12.5 (SE) stromal cells 0.01 mm−2 in the central cornea and 393 ± 21.5 (SE) stromal cells 0.01 mm−2 peripherally. Although this difference is not statistically significant, the cell densities in the central cornea were always larger than those of the peripheral cornea in all eight measurements over a 10.5‐week period, and this difference is significant (P ≤ 0.008, binomial test). Light/dark regimen birds show no such consistent difference in cell densities between central and peripheral corneas. Thus, the density distribution of corneal stromal cells of chicks grown in constant light differs from that of normal chicks. Taken together, all these observations suggest that diurnal cycles of light and darkness are necessary for normal corneal growth.
Ultrastructural evidence of a vesicle‐mediated mode of cell degranulation in chicken chromaffin cells during the late phase of embryonic development
Authors: Crivellato Enrico , Nico Beatrice , Travan Luciana , Isola Miriam , Ribatti Domenico
Published: February 2009

In the present investigation, we attempted to determine whether ultrastructural features indicative of a vesicle‐mediated mode of cell secretion were detectable in chick chromaffin cells during embryo development. The adrenal anlagen of domestic fowls were examined at embryonic days (E) 12, 15, 19 and 21 by electron microscopy quantitative analysis. Morphometric evaluation revealed a series of granule and cytoplasmic changes highly specific for piecemeal degranulation (PMD), a secretory process based on vesicular transport of cargoes from within granules for extracellular release. At E19 and E21 we found a significant peak in the percentage of granules exhibiting changes indicative of progressive release of secretory materials, i.e. granules with lucent areas in their cores, reduced electron density, disassembled matrices, residual cores and membrane empty containers. A dramatic raise in the density of 30–80‐nm‐diameter, membrane‐bound, electron‐dense and electron‐lucent vesicles – which were located either next to granules or close to the plasma membrane – was recognizable at E19, that is, during the prehatching phase. The cytoplasmic burst of dense and clear vesicles was paralleled by the appearance of chromaffin granules showing outpouches or protrusions of their profiles (‘budding features’). These ultrastructural data are indicative of an augmented vesicle‐mediated transport of chromaffin granule products for extracellular release in chick embryo chromaffin cells during the prehatching stage. In conclusion, this study provides new data on the fine structure of chromaffin cell organelles during organ development and suggests that PMD may be part of an adrenomedullary secretory response that occurs towards the end of chicken embryogenesis. From an evolutionary point of view, this study lends support to the concept that PMD is a secretory mechanism highly conserved throughout vertebrate classes.
3D representation of the developing chick knee joint: a novel approach integrating multiple components
Authors: Roddy Karen A. , Nowlan Niamh C. , Prendergast Patrick J. , Murphy Paula
Published: February 2009

The knee joint has a highly complex 3‐dimensional (3D) morphology that is sculpted at the interface of the forming long bones as they are generated in the embryo. Although it is clear that regulatory genes guide joint formation, the mechanisms that are responsible for morphogenesis of the knee are poorly understood. Certainly the process involves integration across several tissues and physical/mechanical influences from neighbouring tissues are important. We describe the acquisition of shape in the chick knee joint in detail and show that by HH34 the joint already displays shape characteristics of the adult structure. Through imaging developing cartilage, tendons, ligaments and muscle across developmental stages from HH28–34 we have built 3D representations of the forming structure including the various components important in knee formation. We describe the timing of muscle and tendon development in parallel with the refinement of cartilage shape, showing when and where (tendon attachment points) muscle forces are applied to the cartilage elements. Shape begins to emerge as the tendons are forming (HH30–32) but is fully refined (HH34) in the presence of tendons. The resulting integrated 3D representations of the developing knee across time will serve as the foundation for computational analysis of the mechanical environment, and experimental approaches to investigating morphogenetic mechanisms.
Cranial dimensions and forces of biting in the domestic dog
Authors: Ellis Jennifer Lynn , Thomason Jeffrey , Kebreab Ermias , Zubair Kasim , France James
Published: February 2009

The purpose of this paper is to analyse the effects of cranial size and shape in domestic dogs (Canis familiaris) on predicted forces of biting. In addition to continuous size‐shape analysis, nine size‐shape groups were developed based on three skull shape categories and three skull size categories. Bite forces were predicted from measurements made on dried skulls using two lever models of the skull, as well as simple models derived by regression analysis. Observed bite force values were not available for the database used in this study, so only comparisons between categories and models were undertaken. The effects of shape and size on scaled predicted bite forces were evaluated. Results show that bite force increases as size increases, and this effect was highly significant (P < 0.0001). The effect of skull shape on bite force was significant in medium and large dogs (P < 0.05). Significant differences were not evident in small dogs. Size × shape interactions were also significant (P < 0.05). Bite force predictions by the two lever models were relatively close to each other, whereas the regression models diverged slightly with some negative numbers for very small dogs. The lever models may thus be more robust across a wider range of skull size‐shapes. Results obtained here would be useful to the pet food industry for food product development, as well as to paleontologists interested in methods of estimating bite force from dry skulls.
C cells evolve at the same rhythm as follicular cells when thyroidal status changes in rats
Authors: Martín‐Lacave Inés , Borrero María J. , Utrilla José C. , Fernández‐Santos José M. , De Miguel Manuel , Morillo Jesús , Guerrero Juan M. , García‐Marín Rocío , Conde Esperanza
Published: February 2009

C cells are primarily known for producing calcitonin, a hypocalcemic and hypophosphatemic hormone. Nevertheless, besides their role in calcium homeostasis, C cells may be involved in the intrathyroidal regulation of follicular cells, suggesting a possible interrelationship between the two endocrine populations. If this premise is true, massive changes induced by different agents in the activity of follicular cells may also affect calcitonin‐producing cells. To investigate the behaviour of C cells in those circumstances, we have experimentally induced two opposite functional thyroid states. We hyperstimulated the follicular cells using a goitrogen (propylthiouracil), and we suppressed thyroid hormone synthesis by oral administration of thyroxine. In both scenarios, we measured T4, TSH, calcitonin, and calcium serum levels. We also completely sectioned the thyroid gland, specifically immunostained the C cells, and rigorously quantified this endocrine population. In hypothyroid rats, not only follicular cells but also C cells displayed hyperplastic and hypertrophic changes as well as increased calcitonin levels. When exogenous thyroxine was administered to the rats, the opposite effect was noted as a decrease in the number and size of C cells, as well as decreased calcitonin levels. Additionally, we noted that the two cell types maintain the same numerical relation (10 ± 2.5 follicular cells per C cell), independent of the functional activity of the thyroid gland. Considering that TSH serum levels are increased in hypothyroid rats and decreased in thyroxine‐treated rats, we discuss the potential involvement of thyrotropin in the observed results.
The connective tissue of the adductor canal – a morphological study in fetal and adult specimens
Authors: De Oliveira Flavia , De Vasconcellos Fontes Ricardo Bragança , Da Silva Baptista Josemberg , Mayer William Paganini , De Campos Boldrini Silvia , Liberti Edson Aparecido
Published: February 2009

The adductor canal is a conical or pyramid‐shaped pathway that contains the femoral vessels, saphenous nerve and a varying amount of fibrous tissue. It is involved in adductor canal syndrome, a claudication syndrome involving young individuals. Our objective was to study modifications induced by aging on the connective tissue and to correlate them to the proposed pathophysiological mechanism. The bilateral adductor canals and femoral vessels of four adult and five fetal specimens were removed en bloc and analyzed. Sections 12 µm thick were obtained and the connective tissue studied with Sirius Red, Verhoeff, Weigert and Azo stains. Scanning electron microscopy (SEM) photomicrographs of the surfaces of each adductor canal were also analyzed. Findings were homogeneous inside each group. The connective tissue of the canal was continuous with the outer layer of the vessels in both groups. The pattern of concentric, thick collagen type I bundles in fetal specimens was replaced by a diffuse network of compact collagen bundles with several transversal fibers and an impressive content of collagen III fibers. Elastic fibers in adults were not concentrated in the thick bundles but dispersed in line with the transversal fiber system. A dynamic compression mechanism with or without an evident constricting fibrous band has been proposed previously for adductor canal syndrome, possibly involving the connective tissue inside the canal. The vessels may not slide freely during movement. These age‐related modifications in normal individuals may represent necessary conditions for this syndrome to develop.
Graft outcomes influenced by co‐expression of Pax7 in graft and host tissue
Authors: Thomas Meghan , Tyers Pam , Lazic Stanley E. , Barker Roger A. , Beazley Lyn , Ziman Mel
Published: February 2009

Cell replacement therapies offer promise in the treatment of neurotrauma and neurodegenerative disorders and have concentrated on the use of primary fetal brain tissue. However, there is a growing promise of using neural stem cells, in which case other factors may be important in their successful engraftment. We therefore investigated whether the co‐expression of the major developmental transcription factor (Pax7 in this study) of donor tissue to graft site influences transplant survival and differentiation in the rat midbrain. Neural progenitor cells were prepared from either the Pax7‐expressing dorsal (DM) or non‐Pax7‐expressing ventral mesencephalon (VM) of embryonic EGFP+/+ rats. Cells were dissociated and grafted into the adult rat superior colliculus (SC) lesioned with quinolinic acid 3 days previously, a time shown to be associated with the up‐regulation of Pax7. Grafts were then examined 4 weeks later. Our results suggest the origin of the graft tissue did not alter graft survival in the SC; however, dorsal grafts appear to have a higher incidence of neuronal survival, whereas ventral grafts have a higher incidence of astrocytic survivors.
Amyloid‐β(1‐42) alters structure and function of retinal pigmented epithelial cells
Authors: Bruban Julien , Glotin Anne‐Lise , Dinet Virginie , Chalour Naïma , Sennlaub Florian , Jonet Laurent , An Na , Faussat Anne Marie , Mascarelli Frédéric
Published: February 2009

Age‐related macular degeneration (AMD) is characterized by the formation of drusen, extracellular deposits associated with atrophy of the retinal pigmented epithelium (RPE), disturbance of the transepithelial barrier and photoreceptor death. Amyloid‐β (Aβ) is present in drusen but its role during AMD remains unknown. This study investigated the in vitro and in vivo effects of the oligomeric form of Aβ(1‐42) – OAβ(1‐42) – on RPE and found that it reduced mitochondrial redox potential and increased the production of reactive oxygen species, but did not induce apoptosis in RPE cell cultures. It also disorganized the actin cytoskeleton and halved occludin expression, markedly decreasing attachment capacity and abolishing the selectivity of RPE cell transepithelial permeability. Antioxidant pretreatment partially reversed the effects of OAβ(1‐42) on mitochondrial redox potential and transepithelial permeability. Subretinally injected OAβ(1‐42) induced pigmentation loss and RPE hypertrophy but not RPE cell apoptosis in C57BL/6 J mice. Rapid OAβ(1‐42)‐induced disorganization of cytoskeletal actin filaments was accompanied by decreased RPE expression of the tight junction proteins occludin and zonula occludens‐1 and of the visual cycle proteins cellular retinaldehyde‐binding protein and RPE65. The number of photoreceptors decreased by half within a few days. Our study pinpoints the role of Aβ in RPE alterations and dysfunctions leading to retinal degeneration and suggests that targeting Aβ may help develop selective methods for treating diseases involving retinal degeneration, such as AMD.
A free radical‐generating system induces the cholesterol biosynthesis pathway: a role in Alzheimer's disease
Authors: Recuero María , Vicente Ma Carmen , Martínez‐García Ana , Ramos María C. , Carmona‐Saez Pedro , Sastre Isabel , Aldudo Jesús , Vilella Elisabet , Frank Ana , Bullido María J. , Valdivieso Fernando
Published: February 2009

Oxidative stress, which plays a critical role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD), is intimately linked to aging – the best established risk factor for AD. Studies in neuronal cells subjected to oxidative stress, mimicking the situation in AD brains, are therefore of great interest. This paper reports that, in human neuronal cells, oxidative stress induced by the free radical‐generating xanthine/xanthine oxidase (X‐XOD) system leads to apoptotic cell death. Microarray analyses showed a potent activation of the cholesterol biosynthesis pathway following reductions in the cell cholesterol synthesis caused by the X‐XOD treatment; furthermore, the apoptosis was reduced by inhibiting 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) expression with an interfering RNA. The potential importance of this mechanism in AD was investigated by genetic association, and it was found that HMGCR, a key gene in cholesterol metabolism and among those most strongly upregulated, was associated with AD risk. In summary, this work presents a human cell model prepared to mimic the effect of oxidative stress in neurons that might be useful in clarifying the mechanism involved in free radical‐induced neurodegeneration. Gene expression analysis followed by genetic association studies indicates a possible link among oxidative stress, cholesterol metabolism and AD.
Anti‐aging activity of the Ink4/Arf locus
Authors: Matheu Ander , Maraver Antonio , Collado Manuel , Garcia‐Cao Isabel , Cañamero Marta , Borras Consuelo , Flores Juana M. , Klatt Peter , Viña Jose , Serrano Manuel
Published: February 2009

The proteins encoded by the Ink4/Arf locus, p16Ink4a, p19Arf and p15Ink4b are major tumour suppressors that oppose aberrant mitogenic signals. The expression levels of the locus are progressively increased during aging and genome‐wide association studies have linked the locus to a number of aging‐associated diseases and frailty in humans. However, direct measurement of the global impact of the Ink4/Arf locus on organismal aging and longevity was lacking. In this work, we have examined the fertility, cancer susceptibility, aging and longevity of mice genetically modified to carry one (Ink4/Arf‐tg) or two (Ink4/Arf‐tg/tg) intact additional copies of the locus. First, increased gene dosage of Ink4/Arf impairs the production of male germ cells, and in the case of Ink4/Arf‐tg/tg mice results in a Sertoli cell‐only‐like syndrome and a complete absence of sperm. Regarding cancer, there is a lower incidence of aging‐associated cancer proportional to the Ink4/Arf gene dosage. Interestingly, increased Ink4/Arf gene dosage resulted in lower scores in aging markers and in extended median longevity. The increased survival was also observed in cancer‐free mice indicating that cancer protection and delayed aging are separable activities of the Ink4/Arf locus. In contrast to these results, mice carrying one or two additional copies of the p53 gene (p53‐tg and p53‐tg/tg) had a normal longevity despite their increased cancer protection. We conclude that the Ink4/Arf locus has a global anti‐aging effect, probably by favouring quiescence and preventing unnecessary proliferation.
Molecular architecture of myelinated peripheral nerves is supported by calorie restriction with aging
Authors: Rangaraju Sunitha , Hankins David , Madorsky Irina , Madorsky Evgenia , Lee Wei‐Hua , Carter Christy S. , Leeuwenburgh Christiaan , Notterpek Lucia
Published: February 2009

Peripheral nerves from aged animals exhibit features of degeneration, including marked fiber loss, morphological irregularities in myelinated axons and notable reduction in the expression of myelin proteins. To investigate how protein homeostatic mechanisms change with age within the peripheral nervous system, we isolated Schwann cells from the sciatic nerves of young and old rats. The responsiveness of cells from aged nerves to stress stimuli is weakened, which in part may account for the observed age‐associated alterations in glial and axonal proteins in vivo. Although calorie restriction is known to slow the aging process in the central nervous system, its influence on peripheral nerves has not been investigated in detail. To determine if dietary restriction is beneficial for peripheral nerve health and glial function, we studied sciatic nerves from rats of four distinct ages (8, 18, 29 and 38 months) kept on an ad libitum (AL) or a 40% calorie restricted diet. Age‐associated reduction in the expression of the major myelin proteins and widening of the nodes of Ranvier are attenuated by the dietary intervention, which is paralleled with the maintenance of a differentiated Schwann cell phenotype. The improvements in nerve architecture with diet restriction, in part, are underlined by sustained expression of protein chaperones and markers of the autophagy–lysosomal pathway. Together, the in vitro and in vivo results suggest that there might be an age‐limit by which dietary intervention needs to be initiated to elicit a beneficial response on peripheral nerve health.
Unmet Mental Health Care Needs for Children with Special Health Care Needs Stratified by Socioeconomic Status
Authors: Fulda Kimberly G. , Lykens Kristine K. , Bae Sejong , Singh Karan P.
Published: February 2009

Background:  The purpose of this research study was to identify factors that affect mental health care for children with special health care needs (CSHCN) and to identify how these factors vary among different socioeconomic levels.

Methods:  Data were obtained from the National Survey of Children with Special Health Care Needs, 2000–2002. The analysis examined the relationships of demographic characteristics, geographical location of household, severity of condition, and social factors on unmet need for mental health care. Multiple logistic regression models were constructed for four socioeconomic status (SES) levels defined by the federal poverty level (FPL): <133%; 133–199%; 200–299%; ≥300%. Standardised regression coefficients were calculated to compare among SES strata.

Results:  There were 38,866 CSHCNs represented in the survey with 9,639 needing mental health care in the past 12 months. The household income distribution was 22% below the 133% FPL, 15% between 133–199% FPL, 18% between 200–299% FPL, and 45% at or above 300% FPL. Black race, ethnicity, insurance type/status, geographical location of household, and number of kids in the household were significant in the <133% of FPL stratum for predicting having received all needed mental health care in the last 12 months. Age and geographical location of household were significant in the 133–199% of FPL stratum. Maternal education was significant in the 200–299% of FPL stratum. Severity of condition, other race, and insurance type/status were significant in the ≥300% of FPL stratum.

Conclusions:  Factors affecting unmet needs for mental health care differed by socioeconomic status. Future research should explore a more in‐depth picture of the CSHCN population that includes stratification by income groups to better understand and serve this population.
An annotated bibliography of GRASP–Part II: Applications
Authors: Festa Paola , Resende Mauricio G. C.
Published: February 2009

A greedy randomized adaptive search procedure (GRASP) is a metaheuristic for combinatorial optimization. It is a multi‐start or iterative process, in which each GRASP iteration consists of two phases, a construction phase, in which a feasible solution is produced, and a local search phase, in which a local optimum in the neighborhood of the constructed solution is sought. Since 1989, numerous papers on the basic aspects of GRASP, as well as enhancements to the basic metaheuristic, have appeared in the literature. GRASP has been applied to a wide range of combinatorial optimization problems, ranging from scheduling and routing to drawing and turbine balancing. This is the second of two papers with an annotated bibliography of the GRASP literature from 1989 to 2008. In the companion paper, algorithmic aspects of GRASP are surveyed. In this paper, we cover the literature where GRASP is applied to scheduling, routing, logic, partitioning, location, graph theory, assignment, manufacturing, transportation, telecommunications, biology and related fields, automatic drawing, power systems, and VLSI design.
Capturing the environment, a metafrontier approach to the drinking water sector
Authors: De Witte Kristof , Marques Rui C.
Published: February 2009

Environmental factors add complexity to the comparison between specific activities or entire entities. Decision making units with an inferior performance are tempted to invoke that their organization is “different” from the others in the data set. By reinterpreting and extending the metafrontier literature, we propose an all‐embracing concept to fully capture the operational environment. We suggest the “Group Specific Technical Efficiency” as a new measure to assess the overall efficiency of a utility while allowing for environmental differences. A real‐world example of drinking water utilities from five different countries illustrates the concept.
A genetic algorithm for a bicriteria supplier selection problem
Authors: Basnet Chuda , Weintraub Andres
Published: February 2009

In this paper, we discuss the problem of selecting suppliers for an organisation, where a number of suppliers have made price offers for supply of items, but have limited capacity. Selecting the cheapest combination of suppliers is a straightforward matter, but purchasers often have a dual goal of lowering the number of suppliers they deal with. This second goal makes this issue a bicriteria problem – minimisation of cost and minimisation of the number of suppliers. We present a mixed integer programming (MIP) model for this scenario. Quality and delivery performance are modelled as constraints. Smaller instances of this model may be solved using an MIP solver, but large instances will require a heuristic. We present a multi‐population genetic algorithm for generating Pareto‐optimal solutions of the problem. The performance of this algorithm is compared against MIP solutions and Monte Carlo solutions.
Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease
Authors: Hadoke Patrick W.F. , Iqbal Javaid , Walker Brian R.
Published: February 2009

The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue‐specific manner by the isozymes of 11β‐hydroxysteroid dehydrogenase. Selective inhibitors of 11β‐hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11β‐hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11β‐hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11β‐hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro‐inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11β‐hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.