bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinct changes in evoked and resting globus pallidus activity in early and late Parkinson's disease experimental models
Authors: Zold Camila L. , Larramendy Celia , Riquelme Luis A. , Murer M. Gustavo
Published: September 2007

The main clinical manifestations of Parkinson's disease are caused by alterations of basal ganglia activity that are tied in with the progressive loss of mesencephalic dopaminergic neurons. Recent theoretical and modeling studies have suggested that changes in resting neuronal activity occurred later in the course of the disease than those evoked by phasic cortical input. However, there is no empirical support for this proposal. Here we report a marked increase in the responsiveness of globus pallidus neurons to electrical motor cortex stimulation, in the absence of noticeable changes in resting activity, in anesthetized rats that had consistently shown a deficit in forelimb use during behavioral testing before the experiments, and had ∼45% dopamine neurons spared in the substantia nigra. Pallidal neurons were also over‐responsive to motor cortex stimulation and lost spatial selectivity for cortical inputs in rats with extensive nigrostriatal damage. After partial lesions, over‐responsiveness was mainly due to an increased proportion of neurons showing excitatory responses, while extensive lesions led to an increased likelihood of inhibitory responding neurons. Changes in resting neuronal activity, comprising pauses disrupting tonic discharge, occurred across different global brain states, including an activated condition which shares similarities with natural patterns of cortical activity seen in awake states and rapid eye‐movement sleep, but only after massive nigrostriatal degeneration. These results suggest that a loss of functional segregation and an abnormal temporal encoding of phasic cortical inputs by globus pallidus neurons may contribute to inducing early motor impairment in Parkinson's disease.
Inhibitory control of the human dorsolateral prefrontal cortex during the anti‐saccade paradigm − a transcranial magnetic stimulation study
Authors: Nyffeler Thomas , Müri René M. , Bucher‐Ottiger Y. , Pierrot‐Deseilligny Charles , Gaymard Bertrand , Rivaud‐Pechoux Sophie
Published: September 2007

In the anti‐saccade paradigm, subjects are instructed not to make a reflexive saccade to an appearing lateral target but to make an intentional saccade to the opposite side instead. The inhibition of reflexive saccade triggering is under the control of the dorsolateral prefrontal cortex (DLPFC). The critical time interval at which this inhibition takes place during the paradigm, however, is not exactly known. In the present study, we used single‐pulse transcranial magnetic stimulation (TMS) to interfere with DLPFC function in 15 healthy subjects. TMS was applied over the right DLPFC either 100 ms before the onset of the visual target (i.e. −100 ms), at target onset (i.e. 0 ms) or 100 ms after target onset (i.e. +100 ms). Stimulation 100 ms before target onset significantly increased the percentage of anti‐saccade errors to both sides, while stimulation at, or after, target onset had no significant effect. All three stimulation conditions had no significant influence on saccade latency of correct or erroneous anti‐saccades. These findings show that the critical time interval at which the DLPFC controls the suppression of a reflexive saccade in the anti‐saccade paradigm is before target onset. In addition, the results suggest the view that the triggering of correct anti‐saccades is not under direct control of the DLPFC.
Facilitation of spinal reflexes assists performing but not learning an obstacle‐avoidance locomotor task
Authors: Michel J. , Van Hedel H.J.A. , Dietz V.
Published: September 2007

The aim of this study was to investigate spinal reflex (SR) modulation during the performance and learning of a precision locomotor task. Healthy subjects had to minimize foot clearance when repeatedly stepping on a treadmill over a randomly approaching obstacle. The subjects walked with reduced vision and were informed about the approaching obstacle and task performance by acoustic warning and feedback signals, respectively. SRs were randomly evoked by tibial nerve stimulation (with non‐nociceptive and nociceptive stimulus intensity) during the mid‐stance phase in both normal and pre‐obstacle stepping. Foot clearance and electromyographic activity of the tibialis anterior and biceps femoris muscles of the right leg were analysed. Only if a delay was introduced between warning signal and nerve stimulation, was the SR amplitude in both muscles enhanced prior to obstacle steps compared with normal steps for both stimulus intensities. Thus, the reflex enhancement depended on the subject's awareness of the approaching obstacle. Improved performance was reflected in a decreased foot clearance, but did not correlate with the course of SR amplitude. It is concluded that obstacle stepping is associated with a facilitation of SR pathways, probably by supraspinal drive. This facilitation might provide assistance in safe obstacle stepping, e.g. to compensate quickly if resistance is encountered.
Early necrosis and apoptosis of Schwann cells transplanted into the injured rat spinal cord
Authors: Hill Caitlin E. , Hurtado Andres , Blits Bas , Bahr Ben A. , Wood Patrick M. , Bartlett Bunge Mary , Oudega Martin
Published: September 2007

Poor survival of cells transplanted into the CNS is a widespread problem and limits their therapeutic potential. Whereas substantial loss of transplanted cells has been described, the extent of acute cell loss has not been quantified previously. To assess the extent and temporal profile of transplanted cell death, and the contributions of necrosis and apoptosis to this cell death following spinal cord injury, different concentrations of Schwann cells (SCs), lentivirally transduced to express green fluorescent protein (GFP), were transplanted into a 1‐week‐old moderate contusion of the adult rat thoracic spinal cord. In all cases, transplanted cells were present from 10 min to 28 days. There was a 78% reduction in SC number within the first week, with no significant decrease thereafter. Real‐time polymerase chain reaction showed a similar 80% reduction in GFP‐DNA within the first week, confirming that the decrease in SC number was due to death rather than decreased GFP transgene expression. Cells undergoing necrosis and apoptosis were identified using antibodies against the calpain‐mediated fodrin breakdown product and activated caspase 3, respectively, as well as ultrastructurally. Six times more SCs died during the first week after transplantation by necrosis than apoptosis, with the majority of cell death occurring within the first 24 h. The early death of transplanted SCs indicates that factors present, even 1 week after a moderate contusion, are capable of inducing substantial transplanted cell death. Intervention by strategies that limit necrosis and/or apoptosis should be considered for enhancing acute survival of transplanted cells.
Cocaine‐ and amphetamine‐regulated transcript peptide (CART) is present in peptidergic C primary afferents and axons of excitatory interneurons with a possible role in nociception in the superficial laminae of the rat spinal cord
Authors: Kozsurek Márk , Lukácsi Erika , Fekete Csaba , Wittmann Gábor , Réthelyi Miklós , Puskár Zita
Published: September 2007

Cocaine‐ and amphetamine‐regulated transcript peptides (CART) have been implicated in the regulation of several physiological functions, including pain transmission. A dense plexus of CART‐immunoreactive fibres has been described in the superficial laminae of the spinal cord, which are key areas in sensory information and pain processing. In this study, we used antibody against CART peptide, together with markers for various types of primary afferents, interneurons and descending systems to determine the origin of the CART‐immunoreactive axons in the superficial laminae of the rat spinal cord. Calcitonin gene‐related peptide (CGRP), a marker for peptidergic primary afferents in the dorsal horn, was present in 72.6% and 34.8% of CART‐immunoreactive axons in lamina I and II, respectively. The majority of these fibres also contained substance P (SP), while a few were somatostatin (SOM)‐positive. The other subpopulation of CART‐immunoreactive boutons in lamina I and II also expressed SP and/or SOM without CGRP, but contained vesicular glutamate transporter 2, which is present mainly in excitatory interneuronal terminals. Our data demonstrate that the majority of CART‐immunoreactive axons in the spinal dorsal horn originate from peptidergic nociceptive primary afferents, while the rest arise from excitatory interneurons that contain SP or SOM. This strongly suggests that CART peptide can affect glutamatergic neurotransmission as well as the release and effects of SP and SOM in nociception and other sensory processes.
CNS‐irrelevant T‐cells enter the brain, cause blood–brain barrier disruption but no glial pathology
Authors: Smorodchenko Alina , Wuerfel Jens , Pohl Elena E. , Vogt Johannes , Tysiak Eva , Glumm Robert , Hendrix Sven , Nitsch Robert , Zipp Frauke , Infante‐Duarte Carmen
Published: September 2007

Invasion of autoreactive T‐cells and alterations of the blood–brain barrier (BBB) represent early pathological manifestations of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). Non‐CNS‐specific T‐cells are also capable of entering the CNS. However, studies investigating the spatial pattern of BBB alterations as well as the exact localization and neuropathological consequences of transferred non‐CNS‐specific cells have been thus far lacking. Here, we used magnetic resonance imaging and multiphoton microscopy, as well as histochemical and high‐precision unbiased stereological analyses to compare T‐cell transmigration, localization, persistence, relation to BBB disruption and subsequent effects on CNS tissue in a model of T‐cell transfer of ovalbumin (OVA)‐ and proteolipid protein (PLP)‐specific T‐cells. BBB alterations were present in both EAE‐mice and mice transferred with OVA‐specific T‐cells. In the latter case, BBB alterations were less pronounced, but the pattern of initial cell migration into the CNS was similar for both PLP‐ and OVA‐specific cells [mean (SEM), 95 × 103 (7.6 × 103) and 88 × 103 (18 × 103), respectively]. Increased microglial cell density, astrogliosis and demyelination were, however, observed exclusively in the brain of EAE‐mice. While mice transferred with non‐neural‐specific cells showed similar levels of rhodamine‐dextran extravasation in susceptible brain regions, EAE‐mice presented huge BBB disruption in brainstem and moderate leakage in cerebellum. This suggests that antigen specificity and not the absolute number of infiltrating cells determine the magnitude of BBB disruption and glial pathology.
Relationship between age and spontaneous ventilation during intravenous anesthesia in children
Authors: BARKER NIGEL , LIM JOANNE , AMARI ERICA , MALHERBE STEPHAN , ANSERMINO J. MARK
Published: September 2007

Background:  Maintaining spontaneous ventilation in children, using total intravenous anesthesia (TIVA), is often desirable, particularly for airway endoscopy. The aim of this study was to evaluate the effect of age on the dose of remifentanil tolerated during spontaneous ventilation under anesthesia maintained with infusions of propofol and remifentanil and to provide guidelines for the administration of remifentanil and propofol to maintain spontaneous ventilation in children.

Methods:  Forty‐five children scheduled for strabismus surgery were divided by age into three groups (group I: 6 months–3 years, group II: 3 years–6 years, and group III: 6 years–9 years). The propofol infusion was titrated using State Entropy as a pharmacodynamic endpoint and remifentanil infused, using a modified up‐and‐down method, with respiratory rate depression as a pharmacodynamic endpoint. A respiratory rate of just greater than 10, stable for 10 min, determined the final remifentanil infusion rate. The group mean was estimated from the final remifentanil infusion rate tolerated (RD50).

Results:  The RD50 of groups I, II, and III were 0.192 (0.08), 0.095 (0.04), and 0.075 (0.03) μg·kg−1·min−1 respectively. Pair‐wise comparisons between the groups for the rate of remifentanil tolerated revealed a statistically significant increase in the RD50 in children less than 3 years of age compared with older children in groups II and III (P < 0.001). The relationship between remifentanil dose and age, weight or height was not linear.

Conclusions:  Younger children, especially those aged less than 3 years, tolerate a higher dose of remifentanil while still maintaining spontaneous respiration. TIVA with spontaneous ventilation is readily achieved in younger children and infants.
Environmental fluctuations can stabilize food web dynamics by increasing synchrony
Authors: Vasseur David A. , Fox Jeremy W.
Published: September 2007

Natural food webs are species‐rich, but classical theory suggests that they should be unstable and extinction‐prone. Asynchronous fluctuations in the densities of competing consumers can stabilize food web dynamics in constant environments. However, environmental fluctuations often synchronize dynamics in nature. Using the same ‘diamond‐shape’ food web model first used to demonstrate the stabilizing effects of asynchrony in constant environments, we show that weak‐to‐moderate environmentally induced fluctuations in consumer mortality rates stabilize food webs while disrupting asynchrony. Synchrony actually promotes stability because: (i) synchronous declines in consumer density reduce the maximum abundance of top predators and (ii) resource competition quickly converts synchronous increases in consumer density into synchronous declines. These results are robust to details of food web topology and the implementation of environmental fluctuations. The fluctuation strengths that enhance stability are within the range experienced naturally by many species, suggesting that stabilization via environmental fluctuations is a realistic possibility.
Thermophilic microbial mats in a tropical geothermal location display pronounced seasonal changes but appear resilient to stochastic disturbance
Authors: Lacap Donnabella C. , Barraquio Wilfredo , Pointing Stephen B.
Published: September 2007

We demonstrate for the first time a dynamic seasonality within thermophilic mat communities in a tropical geothermal spring. Biomass fluctuated such that it is greatest in the dry season, before falling drastically as the summer rains arrive, and then re‐colonization culminates in a new climax in the following dry season. Species richness estimates based upon 16S rRNA gene environmental phylotypes mirrored this pattern, where those unique to the dry season disappear during the wet season only to reappear the following year, and vice versa. Relative abundance of some phototrophic phylotypes was also shown to vary seasonally. Environmental variables within the thermal environment that were most closely correlated to these variations were temperature and phosphate, with the latter a covariable to heavy seasonal tropical monsoon rainfall. Stochastic disturbance caused by a strong typhoon caused significant although temporary effects and both diversity and standing biomass recovered within a few months. Tropical hot spring communities clearly function under a fundamentally different set of abiotic variables from those in temperate locations which do not display seasonality. This is of particular relevance to bioprospecting efforts where targeting the most biodiverse niche is desired, because future sampling strategies for tropical thermal environments should consider diversity on temporal as well as spatial scales.
Pharmacological intervention in prediabetes: considering the risks and benefits
Authors: Del Prato S. , Bianchi C. , Miccoli R. , Penno G.
Published: September 2007

The impact of the diabetes epidemic will be staggering in terms of costs to individuals and society. Social educational initiatives are imperative to altering the lifestyle trends that drive the growth of the epidemic. Targeted lifestyle or drug interventions aimed at preventing progression from prediabetes to type 2 diabetes mellitus carry costs and risks that need to be considered in the context of expected benefits, which also need to be carefully defined. In terms of pharmacological intervention as part of a primary prevention programme, the risk/benefit assessment must include the potential for adverse effects in a large population of asymptomatic individuals, a significant proportion of whom would not progress to diabetes in the absence of treatment and in whom impaired glucose regulation may reflect different underlying pathogenetic mechanisms. Improving the balance of risks and benefits in drug interventions will require a greater ability to determine which treatments are likely to safely improve glucose regulation and prevent diabetes and its adverse cardiovascular outcomes in individual patients.
Childhood obesity: political developments in Europe and related perspectives for future action on prevention
Authors: Fussenegger D. , Pietrobelli A. , Widhalm K.
Published: September 2007

The dramatically increasing prevalence of obesity, especially among children, has become a major public health problem in Europe. In reaction to this alarming trend, a series of initiatives and actions has been launched in recent years. As the potential impact of these activities is widely unknown so far, we underline the need for adequate evaluation of these measures. The aim of this paper is to report the latest developments in the fight against obesity at different political levels across Europe, with special attention to the major results of the recent World Health Organization European Ministerial Conference on Counteracting Obesity. In accordance with the main principles of the European Charter on Counteracting Obesity adopted at the meeting, immediate action should be taken now by implementing the few available schemes with proven effectiveness. Finally, given the lack of appropriate evaluation, we consider it particularly important to establish national research centres to collect country‐specific data that are to be evaluated together by a central European administration department. Based on the results of such a comprehensive data pool, concrete strategies could be developed for future policy building.
Revanchist Urbanism Heads South: The Regulation of Indigenous Beggars and Street Vendors in Ecuador
Authors: Swanson Kate
Published: September 2007

Abstract: Much of the discussion surrounding neoliberal urbanism has been empirically grounded in the North. This paper shifts the discussion south to focus on the regulation of indigenous street vendors and beggars in the Andean nation of Ecuador. Inspired by zero tolerance policies from the North, the cities of Quito and Guayaquil have recently initiated urban regeneration projects to cleanse the streets of informal workers, beggars, and street children. In this paper, I explore the particular and pernicious ways in which these neoliberal urban policies affect indigenous peoples in the urban informal sector. Grounded in the literature on space, race and ethnicity in the Andes, I argue that Ecuador's particular twist on revanchism is through its more transparent engagement with the project ofblanqueamientoor “whitening”. I further argue that Ecuador's “refinement” of revanchist urban policies only works to displace already marginalised individuals and push them into more difficult circumstances.
The Subsumption of Space and the Spatiality of Subsumption: Primitive Accumulation and the Transition to Capitalism in Shanghai, China
Authors: Buck Daniel
Published: September 2007

Abstract: Based on extensive interviews, this study is the first systematic attempt to map the spatio‐temporal evolution of production networks linking urban, state‐owned enterprises and rural, township and village‐owned enterprises in reform‐era China. It identifies two distinct regimes of urban‐to‐rural subcontracting patterns and conventions. The first, which developed and prospered from the mid‐1980s until the mid‐1990s, brought rural workers and the countryside into a relatively extensive relationship with urban capital, and thus represented a partial transition to capitalism. Its violent reconfiguration in the wake of a series of sectoral crises in the late 1990s led to the widespread privatisation of rural enterprises, and the emergence and consolidation of a second regime that simultaneously constituted a significant intensification of relations, the capture of the rural by the urban, and a new stage in this region's transition. This paper argues that these regimes are analogous to the formal and real subsumption of labor to capital, respectively, and that subsumption may be a more useful analytic for understanding the process of capture and transition than primitive accumulation: the latter concept alone, without reference to the dynamics of the social/spatial division of labor, risks missing other ways that exploitive connections can be constructed between places. This paper thus seeks to recast the relationship between these two concepts, and to develop a larger vocabulary in which subsumption, like primitive accumulation, is both spatial and ongoing and internal to capitalist accumulation.
The tortoise and the hare enigma in e‐transformation in Japanese and Korean higher education
Authors: Latchem Colin , Jung Insung , Aoki Kumiko , Ozkul Ali Ekrem
Published: September 2007

Japan and Korea have highly developed information and communications technology infrastructures and have recently reformed their higher education systems and encouraged e‐transformation. However, Japanese universities have not embraced e‐learning as wholeheartedly as their Korean counterparts. The paper concludes that this is due to governmental and institutional failure to develop a cogent vision and strategic plan for e‐learning, to recognise the need for fundamental shifts in organisational cultures and structures and pedagogy and to provide training, funding, recognition and reward for such development. It attributes this to differences in the cultural perspectives, values and customs of the two countries' policy makers, managers and faculty members. The findings are seen to hold important lessons for other countries embarking on e‐transformation.
The Declining Theoretical and Practical Utility of ‘Bandwagoning’: American Hegemony in the Age of Terror
Authors: Beeson Mark
Published: September 2007

One of the most striking features of the ‘war on terror’ has been the support given to the US by a number of key allies like Australia and Britain. Some observers see this as a form of ‘bandwagoning’ in the face of overwhelming American dominance. And yet, not only is American hegemony far less certain of late, but Australia and Britain participated despite rather than because of any immediate benefits. Moreover, some of the US's key rivals like China appear to have benefited by not aligning themselves with the US. This article argues that bandwagoning, both as a theory and as a rationale for policy-making, is inadequate. Consequently, we need to look at more contingent and specific factors if we want to understand the behaviour of America's allies and rivals.
Playing to the Crowd: The Role of Music and Musicians in Political Participation
Authors: Street John , Hague Seth , Savigny Heather
Published: September 2007

Music and politics have long been connected. One of the most recent examples was Live 8 in July 2005, when a series of concerts was used to put pressure on G8 leaders to change their policy on third world debt. While the connection is often observed, it is rarely analysed in any detail. This article is an attempt to provide some of that detail. It begins by asking whether participating in music can also mean participating in politics. It goes on to explore the conditions that are necessary for this conjunction of politics and music. It does this by comparing two UK examples of music-based political movements, Jubilee 2000 (which culminated in Live 8) and Rock Against Racism. It ends by arguing that the link between politics and music has to be understood along three dimensions: the organisation of the link, its legitimation and its cultural performance.
Governance in Africa and Sino-African Relations: Contradictions or Confluence?
Authors: Taylor Ian
Published: September 2007

China's expansion into Africa has attracted a great deal of criticism, particularly regarding its implications for human rights on the continent. However, the nub of the problem is found within Africa itself, within the neo-patrimonial regimes that dominate the continent. Obviously, there is justifiable disquiet that Beijing's Africa policies may undermine political and economic reform on the continent. Nevertheless, the reasons for Africa's current predicament are complex and erecting a potential scapegoat to blame for Africa's woes makes little sense. Before critiquing China's role in Africa vis-à-vis governance and human rights, analysts need to understand both China's particular human rights discourse and the nature of most African states, for it is here that the real problem lies.
China and Northeast Asia: A Complex Equation for ‘Peaceful Rise’
Authors: Chung Jae Ho
Published: September 2007

This article tackles the question: has China become more proactive and willing to resolve regional problems unilaterally, bilaterally or multilaterally? It suggests that, while China has clearly become more proactive in facilitating regional stability and co-operation, it still has to overcome certain perceptual hurdles and constrain its impulse to be the ‘centre’ of the world. Consisting of three sections, this article first discusses the nexus between post-Mao China's ‘new’ diplomacy and Beijing's proactive posture towards Asia and notes the troublesome nature of the regional dynamics in Northeast Asia. It then explores three case studies in which China's activism has varied in resolving intricate regional and inter-state problems: namely, Sino—Japanese discord, the Koguryo controversy between South Korea and China and the North Korean nuclear conundrum. The final section offers some concluding observations regarding China's diplomacy towards Northeast Asia.
Party On? Politicians and Party Switching in Mexico
Authors: Barrow Lynda K.
Published: September 2007

The breakdown of Mexico's hegemonic party system raises questions about the nature of the new system and of the prospects of consolidating Mexican democracy. The concern addressed in this article is that, at the very same time that democratisation has made Mexicans' electoral choices more significant, frequently changing party allegiances among candidates and even elected officials renders these choices less meaningful. Since parties ‘matter’ in a democratic polity, party switching may prove an impediment to the development of a liberal and stable democracy. Partisan shifts within the state congress of Morelos illustrate this point.
Ballot Paper Photographs and Low-Information Elections in Ireland
Authors: Buckley Fiona , Collins Neil , Reidy Theresa
Published: September 2007

In an attempt to facilitate greater voting participation in the Republic of Ireland, photographs of candidates have been placed on the ballot paper for local, national and European elections. Limited research undertaken in advance of the implementation of the photograph policy advised that the measure would assist people with literacy problems. However, social psychology research has long demonstrated that people are willing to make considerable judgements about a person when shown a photograph. The advent of ballot paper photographs allows candidates to be evaluated on the basis of their appearance. This article will explore how photographs could have become a factor in voter decision-making. Providing additional knowledge to encourage greater participation and engagement has introduced a possible new level of superficiality into the voter decision-making process.
A Liberal Defence of Compulsory Voting
Authors: Lacroix Justine
Published: September 2007

At first sight, it might seem difficult to defend compulsory voting from a liberal point of view. Indeed, compulsory voting is widely considered as a breach of individual rights – even if such a minor restriction may be justified for the sake of common good. In this article, I challenge such an interpretation and I present a case for a non-utilitarian conception of compulsory voting. I first emphasise the importance of political participation in the liberal paradigm. I then insist on the notions of autonomy and equal liberty which legitimate compulsory voting in the name of the very principles of political liberalism.
Foreign Money Shocks and the Welfare Performance of Alternative Monetary Policy Regimes*
Authors: Senay Ozge , Sutherland Alan
Published: September 2007

The welfare properties of monetary policy regimes for a country subject to foreign money shocks are examined in a two‐country sticky‐price model. Money targeting is found to be welfare superior to a fixed exchange rate when the expenditure switching effect of exchange rate changes is relatively weak, but a fixed rate is superior when the expenditure switching effect is strong. However, price targeting is superior to both these regimes for all values of the expenditure switching effect. A welfare‐maximising monetary rule yields lower output and exchange rate volatility than price targeting for a wide range of parameter values.
Estimating Risk Attitudes in Denmark: A Field Experiment*
Authors: Harrison Glenn W. , Lau Morten I. , Rutström E. Elisabet
Published: September 2007

We estimate individual risk attitudes using controlled experiments in the field in Denmark. The experiments were carried out across Denmark using a representative sample of 253 people between 19 and 75 years of age. Risk attitudes are estimated for various individuals differentiated by socio‐demographic characteristics. Our results indicate that the average Dane is risk averse, and that risk neutrality is an inappropriate assumption to apply. We also find that risk attitudes vary significantly with respect to several important socio‐demographic variables such as age and education. However, we do not find any effect of sex on risk attitudes.
Too Much of a Good Thing? The Quantitative Economics of R&D‐driven Growth Revisited
Authors: Strulik Holger
Published: September 2007

This article augments an R&D‐based growth model of the third generation with human capital accumulation and impure altruism, calibrates it with U.S. data, and investigates whether the market provides too little or too much R&D. For benchmark parameters, the market share of employment in R&D is close to the socially optimal solution. Sensitivity analysis shows that the order of magnitude of possible deviation between market R&D and optimal R&D is also smaller than suggested by previous studies. Small deviation of total research effort, however, can be compatible with large sectoral misallocations. Furthermore, the model allows for two additional channels through which population growth may affect the resource allocation so that its overall economic impact is no longer predetermined as positive. Numerical calibrations show that economic growth at the average rate in the U.S. over the last century can be consistent with a small and probably negative partial correlation between population growth and economic growth.
Quantitative and qualitative sex differences in spatial navigation
Authors: LÖVDÉN MARTIN , HERLITZ AGNETA , SCHELLENBACH MICHAEL , GROSSMAN‐HUTTER BARBARA , KRÜGER ANTONIO , LINDENBERGER ULMAN
Published: September 2007

We examined sex differences in spatial navigation performance using an ecologically relevant experimental paradigm in which virtual maze‐like museums are projected in front of a treadmill. Thirty‐two 20–30‐year‐old adults (16 women/16 men) performed a way‐finding task in city‐block (straight corridors) or variable (irregular corridors) topographies while walking on the treadmill. Sex differences in spatial navigation performance were reduced in variable topographies, suggesting less reliance on spatial relational learning among women. Also, spatial geometric knowledge of the mazes continued to be higher in men after all participants had attained perfect place‐finding performance. Results indicate that sex differences in spatial navigation performance are modulated by interactions between environmental demands and sex differences in spatial processing.
Achieving what cannot be done: Coping with the time constants in a dynamic decision task by doing something else
Authors: BREHMER BERNDT , NÄHLINDER STAFFAN
Published: September 2007

This study examines how people handle the time constants in dynamic decision tasks, using a microworld called NEWFIRE which simulates forest fire fighting. The results showed that the participants did not adapt to the time constants, as shown by the fact that they did not discriminate between fires requiring different number of fire fighting units when varying the number of fire fighting units was a means of compensating for the time constants. If they were allowed to move units before the fire started their performance improved, suggesting that they could compensate for their problems with the time constants by restructuring the task in such a way that they did not need to consider them. It is suggested that such restructuring may well be how people handle dynamic tasks also in other circumstances, and that more effort should be put into studying what people actually do in dynamic tasks, rather than into only assessing whether or not they perform optimally.
Why Is the Intelligence Community So Difficult to Redesign? Smart Practices, Conflicting Goals, and the Creation of Purpose‐Based Organizations
Authors: HAMMOND THOMAS H.
Published: September 2007

The adoption of “smart practices” requires that smart practices can actually be identified for the areas of public policy in which we are interested. For the problem of designing structures for public agencies, however, identifying smart practices is not easy. This article explores the reasons for the substantial conservativism, lasting over 50 years, regarding the structural design of the U.S. intelligence community. One central argument is simply that it was very difficult to discover a clearly superior structure; in fact, the long‐standing structure may have had some unrecognized virtues. But the other central argument is that one smart practice may have emerged since the 9/11 attacks: It involves the creation of problem‐focused interagency centers that are intended to enhance the sharing and integration of information within the intelligence community. These conclusions about redesigning the structure of the intelligence community are based on the arguments of Luther Gulick on methods of departmentalization and Martin Landau on redundancy and system reliability.
Beyond Kyoto: Climate Change Policy in Multilevel Governance Systems
Authors: RABE BARRY G.
Published: September 2007

Climate change policy has commonly been framed as a matter of international governance for which global policy strategies can be readily employed. The decade of experience following the 1997 signing of the Kyoto Protocol suggests a far more complex process involving a wide range of policy options and varied engagement by multiple levels of governance systems. The respective experiences of the United States and Canada suggest that formal engagement in the international realm of policy is not a good indicator of domestic policy development or emissions reductions. The different contexts of intergovernmental relations, varied resources available to subnational governments for policy development and implementation, and role of subnational leaders in policy formation have emerged as important factors in explaining national differences between these North American neighbors. Consequently, climate change increasingly presents itself as a challenge not only of international relations but also of multilevel governance, thereby creating considerable opportunity to learn from domestic policy experimentation.
Regulatory Agencies—The Challenges of Balancing Agency Autonomy and Political Control
Authors: CHRISTENSEN TOM , LÆGREID PER
Published: September 2007

In this article we focus on the dynamic interplay between increase in autonomy of regulatory agencies and political control of those agencies. The general research issues are the weak empirical foundations of regulatory reforms, the complex trade‐off between political control and agency autonomy, the dual process of deregulation and reregulation, the problems of role‐specialization and coordination, and the questions of “smart practice” in regulatory policy and practice. The theoretical basis is agency theories and a broad institutional approach that blend national political strategies, historical‐cultural context, and external pressures to understand regulatory agencies and regulatory reform. This approach is contrasted with a practitioner model of agencies. Empirically the article is based on regulatory reform in Norway, giving a brief introduction to the reform and agency context followed by an analysis of the radical regulatory reform policy introduced recently by the current Norwegian government. We illustrate how regulatory reforms and agencies work in practice by focusing on two specific cases on homeland security and telecommunications.
A genetic survey of heavily exploited, endangered turtles: caveats on the conservation value of trade animals
Authors: Fong J. J. , Parham J. F. , Shi H. , Stuart B. L. , Carter R. L.
Published: September 2007

Asian turtles face an extinction crisis, and so it is imperative that systematists accurately determine species diversity in order to guide conservation strategies effectively. We surveyed mitochondrial and nuclear DNA (mtDNA and nuDNA) variation of the heavily exploited Mauremys mutica complex, a clade of Asian turtles that contains the endangered M. mutica from Japan, Taiwan, China and Vietnam, and the critically endangered Mauremys annamensis from central Vietnam. We discovered extensive mtDNA and nuDNA variation among samples that did not correspond to the currently recognized taxonomy. Both nuDNA and mtDNA data suggest that M. mutica is paraphyletic with respect to M. annamensis. Surprisingly, M. annamensis exhibits a previously unknown mtDNA structure in the form of two clades that are paraphyletic to M. mutica. These data reveal that the currently recognized taxonomy of the mutica complex does not reflect the genetic diversity of our samples. Unfortunately, many conservation‐oriented captive‐breeding efforts for turtles are also based on trade samples such as the ones studied here. These efforts include plans to breed trade‐rescued individuals and release their progeny into the wild. Because our genetic survey reveals that the taxonomic identity of these samples does not reflect genetic diversity, we raise serious questions about the efficacy of these programs. In order to address conservation issues and provide more accurate estimates of evolutionary lineages within Mauremys, we recommend continued surveys for wild populations of the mutica complex to provide new genetic material and additional distributional data, attempts to extract DNA from historic museum specimens and a shift in conservation focus to in situ preservation of wild populations and associated habitat.
What happens if density increases? Conservation implications of population influx into refuges
Authors: Metcalf C. J. E. , Hampson K. , Koons D. N.
Published: September 2007

Sudden catastrophic events like fires, hurricanes, tsunamis, landslides and deforestation increase population densities in habitat fragments, as fleeing animals encroach into these refuges. Such sudden overcrowding will trigger transient fluctuations in population size in the refuges, which may expose refuge populations to an increased risk of extinction. Until recently, detailed information about the operation of density dependence in stage‐structured populations, and tools for quantifying the effects of transient dynamics, have not been available, so that exploring the extinction risk of such transient fluctuations has been intractable. Here, we use such recently developed tools to show that extinction triggered by overcrowding can threaten populations in refuges. Apart from situations where density dependence acts on survival, our results indicate that short‐lived species may be more at risk than longer‐lived species. Because dynamics in local populations may be critical for the preservation of metapopulations and rare species, we argue that this aspect warrants further attention from conservation biologists.
Uniparental (mtDNA, Y‐chromosome) Polymorphisms in French Guiana and Two Related Populations – Implications for the Region's Colonization
Authors: Mazières S. , Guitard E. , Crubézy E. , Dugoujon J.‐M. , Bortolini M. C. , Bonatto S. L. , Hutz M. H. , Bois E. , Tiouka F. , Larrouy G. , Salzano F. M.
Published: September 2007

Blood samples collected in four Amerindian French Guiana populations (Palikur, Emerillon, Wayampi and Kali'na) in the early 1980s were screened for selected mtDNA and Y‐chromosome length polymorphisms, and sequenced for the mtDNA hypervariable segment I (HVS‐I). In addition, two other Amerindian populations (Apalaí and Matsiguenga) were examined for the same markers to establish the genetic relationships in the area. Strong dissimilarities were observed in the distribution of the founding Amerindian haplogroups, and significant p‐values were obtained from FSTgenetic distances. Interpopulation similarities occurred mainly due to geography. The Palikur did not show obvious genetic similarity to the Matsiguenga, who speak the same language and live in a region from where they could have migrated to French Guiana. The African‐origin admixture observed in the Kali'na probably derives from historical contacts they had with the Bushinengue (Noir Marron), a group of escaped slaves who now lead independent lives in a nearby region. This analysis has identified significant clues about the Amerindian peopling of the North‐East Amazonian region.
Leisure time physical exercise during pregnancy and the risk of miscarriage: a study within the Danish National Birth Cohort
Authors: Madsen M , Jørgensen T , Jensen ML , Juhl M , Olsen J , Andersen PK , Nybo Andersen A‐M
Published: September 2007

Objective  To examine the association between leisure time physical exercise during pregnancy and the risk of miscarriage.

Design  Prospective study with elements of retrospective data collection.

Setting  Denmark 1996–2002.

Population  A total of 92 671 pregnant women enrolled in the Danish National Birth Cohort and interviewed subsequently.

Methods  Data on exercise during pregnancy and potential confounders were obtained through computer‐assisted telephone interviews either during pregnancy or after an early miscarriage. Outcome of pregnancy was identified by register linkage. Using Cox regression analysis, we estimated the hazard ratio (HR) of miscarriage according to weekly amount of exercise and the type of exercise. The HR was estimated for <11, 11–14, 15–18, and 19–22 weeks of gestation, respectively.

Main outcome measures  Miscarriage, defined as fetal loss before 22 completed weeks of gestation.

Results  A stepwise increasing relation was found between amount of exercise and risk of miscarriage, where risk of miscarriage increased by amount of exercise up to HR = 3.7 (95% CI 2.9–4.7) for women who exercised more than 7 hours per week compared with nonexercisers. Particularly ‘high‐impact exercise’ was associated with an increased risk of miscarriage. No association was seen between exercise and risk of miscarriage after 18 weeks of gestation.

Conclusions  This study suggests that exercise early in pregnancy is associated with an increased risk of miscarriage. The results should, however, be interpreted cautiously as potential bias arising from retrospective data collection may explain part of the association.
Vesicular release of glutamate mediates bidirectional signaling between astrocytes and neurons
Authors: Ni Yingchun , Malarkey Erik B. , Parpura Vladimir
Published: September 2007

The major excitatory neurotransmitter in the CNS, glutamate, can be released exocytotically by neurons and astrocytes. Glutamate released from neurons can affect adjacent astrocytes by changing their intracellular Ca2+ dynamics and, vice versa, glutamate released from astrocytes can cause a variety of responses in neurons such as: an elevation of [Ca2+]i, a slow inward current, an increase of excitability, modulation of synaptic transmission, synchronization of synaptic events, or some combination of these. This astrocyte‐neuron signaling pathway might be a widespread phenomenon throughout the brain with astrocytes possessing the means to be active participants in many functions of the CNS. Thus, it appears that the vesicular release of glutamate can serve as a common denominator for two of the major cellular components of the CNS, astrocytes and neurons, in brain function.
The differential effects of single or repeated restraint stress on kainic acid‐induced neuronal death in the hippocampal CA3 region: the role of glucocorticoid and various signal molecules
Authors: Kwon Min‐Soo , Seo Young‐Jun , Choi Seung‐Min , Choi Hee‐Woo , Jung Jun‐Sub , Park Soo‐Hyun , Suh Hong‐Won
Published: September 2007

The effect of stress mediators following the stress period and addition time is a controversial issue until now. Thus, we aim to clarify the differential effects of single restraint stress (SS) or repeated restraint stress (RS) on kainic acid (KA)‐induced neuronal death especially as addressing not only the role of glucocorticoid (Gc) and its receptor but also the signal pathway leading to cAMP response element binding protein phosphorylation (pCREB) and its functional role during stress. In the present study, we found that although RS did not show any difference on serum Gc level and hippocampal Gc receptor level compared to SS, SS exacerbated KA‐induced neuronal death in hippocampal CA3 region, but RS did not. Moreover, pre‐treatment with RU 38486 (Gc receptor antagonist) abolished the effect of SS on KA‐induced neuronal death without an effect on KA toxicity itself. Furthermore, RS aggravates KA‐induced neuronal death when CREB phosphorylation was deprived by KN‐93 (calcium/calmodulin‐dependent protein kinase II inhibitor). However, other signal molecules inhibitors such as PD98059 (MEK1/2 inhibitor) and SP600125 (p‐p38 inhibitor) have no effect on KA‐induced neuronal death after RS although these signal molecule were increased during SS or RS. These findings suggest that pCREB expression via calcium/calmodulin‐dependent protein kinase II phosphorylation during RS comprise one of the balancers against Gc induced by stress.