bluuebunny/crossref_metadata_2025 huggingface dataset:
E‐safety and Web 2.0 for children aged 11–16
Authors: Sharples M. , Graber R. , Harrison C. , Logan K.
Published: January 2009

Abstract  This paper reports findings from a survey and interviews with children aged 11–16 years, teachers and parents on their attitudes to e‐safety in relation to social networking and media creation (Web 2.0) and their practices at school and at home. The results showed that 74% of the children surveyed have used social network (SN) sites and that a substantial minority regularly interact socially online with people they have not met face‐to‐face. Online interaction forms a different, although overlapping, social space to that of face‐to‐face friendships. Despite a desire from some teachers to explore the benefits of Web 2.0 for creative and social learning, they report being constrained by a need to show a duty of care that avoids worst‐case risk to children, to restrict access to SN sites. The respondents also report more direct concerns about Internet bullying and exam cheating. We also report a Policy Delphi process with a panel of 30 people with expertise in Web 2.0 and e‐safety. The panel reached a general consensus that schools should move towards allowing access to Web 2.0 sites, with children being educated in responsible and creative learning.
The appropriation and repurposing of social technologies in higher education
Authors: Hemmi A. , Bayne S. , Land R.
Published: January 2009

Abstract  This paper presents some of the findings from a recent project that conducted a virtual ethnographic study of three formal courses in higher education that use ‘Web 2.0’ or social technologies for learning and teaching. It describes the pedagogies adopted within these courses, and goes on to explore some key themes emerging from the research and relating to the pedagogical use of weblogs and wikis in particular. These themes relate primarily to the academy's tendency to constrain and contain the possibly more radical effects of these new spaces. Despite this, the findings present a range of student and tutor perspectives which show that these technologies have significant potential as new collaborative, volatile and challenging environments for formal learning.
Control of translation initiation involves a factor‐induced rearrangement of helix 44 of 16S ribosomal RNA
Authors: Qin Daoming , Fredrick Kurt
Published: January 2009

Initiation of translation involves recognition of the start codon by the initiator tRNA in the 30S subunit. To investigate the role of ribosomal RNA (rRNA) in this process, we isolated a number of 16S rRNA mutations that increase translation from the non‐canonical start codon AUC. These mutations cluster to distinct regions that overlap remarkably well with previously identified class III protection sites and implicate both IF1 and IF3 in start codon selection. Two mutations map to the 790 loop and presumably act by inhibiting IF3 binding. Another cluster of mutations surrounds the conserved A1413∘G1487 base pair of helix 44 in a region known to be distorted by IF1 and IF3. Site‐directed mutagenesis in this region confirmed that this factor‐induced rearrangement of helix 44 helps regulate initiation fidelity. A third cluster of mutations maps to the neck of the 30S subunit, suggesting that the dynamics of the head domain influences translation initiation. In addition to identifying mutations that decrease fidelity, we found that many P‐site mutations increase the stringency of start codon selection. These data provide evidence that the interaction between the initiator tRNA and the 30S P site is tuned to balance efficiency and accuracy during initiation.
Vectorial transport and folding of an autotransporter virulence protein during outer membrane secretion
Authors: Junker Mirco , Besingi Richard N. , Clark Patricia L.
Published: January 2009

Autotransporter (AT) proteins are a large and diverse family of extracellular virulence proteins from Gram‐negative bacteria, characterized by a central β‐helix domain within the mature virulence protein. It is not clear how these proteins cross the outer membrane (OM) quickly and efficiently, without assistance from an external energy source such as ATP or a proton gradient. Conflicting results in the literature have led to several proposed mechanisms for AT OM secretion, including a concerted process, or vectorial secretion with different directionalities. We introduced pairs of cysteine residues into the passenger sequence of pertactin, an AT virulence protein from Bordetella pertussis, and show that OM secretion of the passenger domain stalls due to the formation of a disulphide bond. We further show that the C‐terminus of the pertactin passenger domain β‐helix crosses the OM first, followed by the N‐terminal portions of the virulence protein. In vivo proteolytic digestion shows that the C‐terminus is exposed to the extracellular milieu during stalling, and forms stable structure. These AT secretion and folding features can potentially facilitate efficient secretion.
Methylene tetrahydrofolate dehydrogenase/cyclohydrolase and the synthesis of 10‐CHO‐THF are essential inLeishmania major
Authors: Murta Silvane M. F. , Vickers Tim J. , Scott David A. , Beverley Stephen M.
Published: January 2009

10‐Formyl tetrahydrofolate (10‐CHO‐THF) is a key metabolite in C1 carbon metabolism, arising through the action of formate‐tetrahydrofolate ligase (FTL) and/or 5,10‐methenyltetrahydrofolate cyclohydrolase/5,10‐methylene tetrahydrofolate dehydrogenase (DHCH).Leishmania majorpossesses singleDHCH1andFTLgenes encoding exclusively cytosolic proteins, unlike other organisms where isoforms occur in the mitochondrion as well. Recombinant DHCH1 showed typical NADP+‐dependent methylene tetrahydrofolate DH and 5,10‐methenyltetrahydrofolate CH activities, and the DH activity was potently inhibited by a substrate analogue 5,10‐CO‐THF (Ki105 nM), as wasLeishmaniagrowth (EC501.1 μM). Previous studies showed nullftl‐mutants were normal, raising the possibility that loss of the purine synthetic pathway had rendered 10‐CHO‐THF dispensable in evolution. We were unable to generatedhch1‐null mutants by gene replacement, despite using a wide spectrum of nutritional supplements expected to bypass DHCH function. We applied an improved method for testing essential genes inLeishmania, based on segregational loss of episomal complementing genes rather than transfection; analysis of ∼1400 events without successful loss ofDHCH1again established its requirement. Lastly, we employed ‘genetic metabolite complementation’ using ectopically expressedFTLas an alternative source of 10‐CHO‐THF; nowdhch1‐null parasites were readily obtained. These data establish a requirement for 10‐CHO‐THF metabolism inL. major, and provide genetic and pharmacological validation of DHCH as a target for chemotherapy, in this and potentially other protozoan parasites.
Community‐based distribution of sulfadoxine‐pyrimethamine for intermittent preventive treatment of malaria during pregnancy improved coverage but reduced antenatal attendance in southern Malawi
Authors: Msyamboza K. P. , Savage E. J. , Kazembe P. N. , Gies S. , Kalanda G. , D’Alessandro U. , Brabin B. J.
Published: January 2009

Objective  To evaluate the impact of a 2‐year programme for community‐based delivery of sulfadoxine‐pyremethamine (SP) on intermittent preventive treatment during pregnancy coverage, antenatal clinic attendance and pregnancy outcome.

Methods  Fourteen intervention and 12 control villages in the catchment areas of Chikwawa and Ngabu Government Hospitals, southern Malawi, were selected. Village‐based community health workers were trained in information, education and counselling on malaria control in pregnancy and the importance of attending antenatal clinics and promoted these messages to pregnant women. In the intervention group community health workers also distributed SP to pregnant women.

Results  In the control area, coverage of intermittent preventive treatment during pregnancy (>2 doses) was low before (44.1%) and during the intervention (46.1%). In the intervention area, coverage increased from 41.5% to 82.9% (P < 0.01). Antenatal clinic attendance (>2 visits) was maintained in control villages at above 90%, but fell in intervention villages from 87.3% to 51.5% (P < 0.01). Post‐natal malaria parasitaemia prevalence fell in women from both study areas during the intervention phase (P < 0.05). Increasing the coverage of intermittent preventive treatment during pregnancy to >40% did not significantly improve maternal haemoglobin or reduce low birthweight prevalence.

Conclusions  Better coverage of community‐based intermittent preventive treatment during pregnancy can lower attendance at antenatal clinics; thus its effect on pregnancy outcome and antenatal attendance need to be monitored.
The biosocial dynamics of tuberculosis
Authors: Grange John M. , Kapata Nathan , Chanda Duncan , Mwaba Peter , Zumla Alimuddin
Published: January 2009

The declaration by the WHO of tuberculosis as a ‘global emergency’ illustrates the paradox of tuberculosis. The treatment of this disease is a good example of ‘evidence‐based medicine’, having been fine‐tuned by numerous clinical trials. Modern short‐course anti‐tuberculosis therapy is among the most effective and cost‐effective ways of saving and prolonging human life; yet, this disease is more prevalent today than in the days before the advent of effective therapy and is currently the cause of one in seven deaths and one in four preventable deaths among young adults. It would seem that something has gone seriously wrong and, to shed light on the cause, it is necessary to take a very broad historical look at the changing trends in the behaviour of the disease in communities worldwide and the attitudes of the various communities to the disease in their midst, not just to understand past mistakes, but to make sure we do not make the same mistakes now and in the future.
Dietary exclusions for improving established atopic eczema in adults and children: systematic review
Authors: Bath‐Hextall F. , Delamere F. M. , Williams H. C.
Published: January 2009

Atopic eczema is the most common inflammatory skin disease of childhood in developed countries. We performed a systematic review of randomized controlled trials to assess the effects of dietary exclusions for the treatment of established atopic eczema. Nine trials (421 participants) were included, most of which were poorly reported. Six were studies of egg and milk exclusion (n = 288), one was a study of few foods (n = 85) and two were studies of an elemental diet (n = 48). There appears to be no benefit of an egg‐ and milk‐free diet in unselected participants with atopic eczema. There is also no evidence of benefit in the use of an elemental or few‐foods diet in unselected cases of atopic eczema. There may be some benefit in using an egg‐free diet in infants with suspected egg allergy who have positive specific IgE to eggs – one study found 51% of the children had a significant improvement in body surface area with the exclusion diet as compared with normal diet (95% CI 1.07–2.11) and change in surface area and severity score was significantly improved in the exclusion diet as compared with the normal diet at the end of 6 weeks (MD 5.50, 95% CI 0.19–10.81) and end of treatment (MD 6.10, 95% CI 0.06–12.14). Despite their frequent use, we find little good quality evidence to support the use of exclusion diets in atopic eczema.
Adrenaline for the treatment of anaphylaxis: cochrane systematic review
Authors: Sheikh A. , Shehata Y. A. , Brown S. G. A. , Simons F. E. R.
Published: January 2009

Background:  Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death. Adrenaline is recommended as the initial treatment of choice for anaphylaxis.

Objectives:  To assess the benefits and harms of adrenaline in the treatment of anaphylaxis.

Methods:  We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1), MEDLINE (1966 to March 2007), EMBASE (1966 to March 2007), CINAHL (1982 to March 2007), BIOSIS (to March 2007), ISI Web of Knowledge (to March 2007) and LILACS (to March 2007). We also searched websites listing ongoing trials: http://www.clinicaltrials.gov/, http://www.controlledtrials.com and http://www.actr.org.au/ and contacted pharmaceutical companies and international experts in anaphylaxis in an attempt to locate unpublished material. Randomized and quasi‐randomized controlled trials comparing adrenaline with no intervention, placebo or other adrenergic agonists were eligible for inclusion. Two authors independently assessed articles for inclusion.

Results:  We found no studies that satisfied the inclusion criteria.

Conclusions:  On the basis of this review, we are unable to make any new recommendations on the use of adrenaline for the treatment of anaphylaxis. In the absence of appropriate trials, we recommend, albeit on the basis of less than optimal evidence, that adrenaline administration by intramuscular injection should still be regarded as first‐line treatment for the management of anaphylaxis.
Single transpulmonary thermodilution and continuous monitoring of central venous oxygen saturation during off‐pump coronary surgery
Authors: SMETKIN A. A. , KIROV M. Y. , KUZKOV V. V. , LENKIN A. I. , EREMEEV A. V. , SLASTILIN V. Y. , BORODIN V. V. , BJERTNAES L. J.
Published: January 2009

Background:Off‐pump coronary artery bypass grafting (OPCAB) requires thorough monitoring of hemodynamics and oxygen transport. Our aim was to find out whether therapeutic guidance during and after OPCAB, using an algorithm based on advanced monitoring, influences perioperative hemodynamic and fluid management as well as the length of post‐operative ICU and hospital stay.

Methods:Patients were randomized into two groups of hemodynamic monitoring: the conventional monitoring (CM) group (n=20) and the advanced monitoring (AM) group (n=20). In the CM group, therapy was guided by central venous pressure, mean arterial pressure (MAP) and heart rate (HR), and in the AM group by the intrathoracic blood volume index, MAP, HR, central venous oxygen saturation (ScvO2) and cardiac index (CI). The measurements were performed before and during surgery, and at 2, 4 and 6 h post‐operatively.

Results:In the AM group, colloids and dobutamine were given more frequently and were accompanied by increments in ScvO2, CI and oxygen delivery compared with baseline. The percentage of ephedrine administration was higher in the CM group. The algorithm guided by AM decreased time until achieving the status of ‘fit for ICU discharge’ and post‐operative hospital stay by 15% and 25%, respectively.

Conclusions:A goal‐directed algorithm based on advanced hemodynamic monitoring and continuous measurement of ScvO2facilitates early detection and correction of hemodynamic changes and influences the strategy for fluid therapy that can improve the course of post‐operative period after coronary artery bypass grafting on the beating heart.
From student to therapist: Follow up of a first cohort of Bachelor of Occupational Therapy students
Authors: Doherty Georgina , Stagnitti Karen , Schoo Adrian M. M.
Published: January 2009

Aim:  This study aimed to investigate the perception of graduate students on their preparation for practice, at 7 months post graduation.

Method:  Using an anonymous postal questionnaire, 18 respondents (58% response rate) provided data on the nature of current employment, the experience as a graduate therapist, and perceptions of their undergraduate experience in preparing them for practice.

Results:  Fifty percent of the respondents were practising in a rural environment. There was a significant positive relationship between respondents perception of their curriculum and fieldwork experiences and their preparation for practice (rho = 0.52, p < 0.05, and rho = 0.55, p < 0.05, respectively). Of the fieldwork experiences, respondents rated block placements as more beneficial to practice than non‐traditional placements. However, a correlational analysis showed the non‐traditional placement was significantly related to preparation for practice (rho = 0.54, p < 0.05). On a seven‐point Likert scale, respondents rated themselves from 5.2 to 5.7 for perceived self‐competence as a newly graduated practitioner with community‐based graduates having the higher rating. Confidence in clinical decision‐making was rated 5.0 to 5.6 with community‐based graduates having higher rating. Respondents reported a positive perception that the undergraduate program prepared them to enter the workforce and practise as an occupational therapist (mean ratings 5.5 to 6.2).

Conclusion:  Respondents felt adequately prepared to enter the occupational therapy profession and workforce. Strengths and weaknesses in their preparation are discussed as well as the need for further research.
Evaluation of modern pathological criteria for positive margins in radical prostatectomy specimens and their use for predicting biochemical recurrence
Authors: Bong Gary W. , Ritenour Chad W.M. , Osunkoya Adeboye O. , Smith M. Timothy , Keane Thomas E.
Published: January 2009

OBJECTIVES

To assess the interpretation of modern criteria for evaluating surgical margins (SMs), by examining the incidence of positive SMs (PSMs) and subsequent biochemical recurrence in a single‐surgeon series of radical prostatectomy (RP) at two institutions, as the criteria for determining PSMs after RP are subject to individual interpretation, and this might explain some of the variability in biochemical recurrence rates with different rates of PSMs.

PATIENTS AND METHODS

We reviewed 301 consecutive perineal RPs by one surgeon (T.K.) at Emory University Hospital (EUH) and the Medical University of South Carolina (MUSC), with each pathology department using modern criteria to evaluate the SMs. The SM status and biochemical recurrence (BCR) were analysed, the latter defined as a prostate‐specific antigen level of ≥0.2 ng/mL.

RESULTS

There were 158 perineal RPs at EUH followed by 143 at MUSC. PSMs were reported in 39 patients (24.7%) at EUH, whereas six (4.2%) were positive at MUSC. The overall BCR rates were similar between the groups, but BCR within margin‐positive cases was 100% at MUSC vs 25.6% at EUH (P < 0.01). The presence of tumour at <1 mm from the margin did not increase the rate of BCR compared to those with obvious negative SMs (P = 0.731).

CONCLUSION

In this single‐surgeon series, using the same criteria to evaluate the SMs resulted in significantly different PSM rates and margin‐positive BCR rates between the institutions. Although the reason for these differences is difficult to determine, the study shows clearly that tumour within 1 mm of the margin should not be classified as margin‐positive.
Media as a Mechanism of Institutional Change and Reinforcement
Authors: Coyne Christopher J. , Leeson Peter T.
Published: January 2009

We argue that mass media is a mechanism of institutional evolution and identify three important effects media has on institutions. The ‘gradual effect’ involves media contributing to marginal changes in existing institutions. The ‘punctuation effect’ involves media catalyzing rapid institutional overhaul. The ‘reinforcement effect’ involves media contributing to the durability and sustainability of punctuated institutional equilibria. Our analysis identifies a paradoxical relationship between mass media and institutions wherein media both changes and reinforces existing institutions. This finding resolves a tension in the institutional literature that defines institutions by their durability but recognizes we observe (sometimes rapid and radical) institutional change. Case studies from the collapse of communism in Poland and Russia illustrate our argument.
Does Too Much Trust Hamper Economic Growth?
Authors: Roth Felix
Published: January 2009

This paper examines the relationship between trust and economic growth. Taking panel data and using a fixed‐effects estimation for a 41‐country sample over the time period from 1980 to 2004 and with a total of 129 observations, the paper points out that economic growth is negatively related to an increase in trust. This negative finding is in contrast to most empirical findings using a cross‐sectional design. The common knowledge which has governed the nature of discussions in social science and economics for the last ten years, that trust is generally positively related to economic performance, must be seriously questioned. From a policy point of view an increase in trust is crucial for countries with low levels of trust, but can likely be neglected by countries with sufficient levels of trust and may even hamper economic performance in countries with high levels of trust. The relationship is tested in the context of EU countries, OECD countries and developing countries. Interpersonal trust and systemic trust is differentiated.
Trust and Success in Venture Capital Financing—an Empirical Analysis with German Survey Data
Authors: Duffner Stefan , Schmid Markus M. , Zimmermann Heinz
Published: January 2009

This paper presents an empirical analysis of the role of trust in the relationship between venture capitalist and entrepreneur. Following the social sciences literature, we try to differentiate between trust as an affective, value‐based category from confidence which is understood as a backward‐looking, evidence‐based mechanism. Using data from a survey among German venture capitalists conducted in 2003, we analyze 111 financing relationships from 75 respondents. We find a significant reciprocal positive relationship between trust and success. Other significant determinants of trust include the perceived quality of the entrepreneur and credibility of information (two proxy variables for measuring confidence), the perceived importance of reputation and the stage of the entrepreneur's venture. The level of monitoring and control is identified as a substitute for trust. We address a potential endogeneity of trust and success by estimating a system of two simultaneous equations by 3SLS and find the results to be robust. Finally, we use data from a second survey conducted in 2006 to assess whether trust predicts success. In fact, our results indicate that a higher level of trust in 2003 is associated with a higher success rate in 2006.
The interface between obesity and periodontitis with emphasis on oxidative stress and inflammatory response
Authors: Boesing F. , Patiño J. S. R. , Da Silva V. R. G. , Moreira E. A. M.
Published: January 2009

Obesity is characterized by the abnormal or excessive deposition of fat in the adipose tissue. Its consequences go far beyond adverse metabolic effects on health, causing an increase in oxidative stress that leads not only to endothelial dysfunction but also to negative effects in relation to periodontitis, because of the increase in proinflammatory cytokines. Thus, obesity appears to participate in the multifactorial phenomenon of causality of periodontitis through the increased production of reactive oxygen species. Within this context, this paper aims to highlight, by analysis and description of previous studies, the interface between obesity and periodontitis, with emphasis on oxidative stress and the inflammatory response.
Partial 3D Shape Retrieval by Reeb Pattern Unfolding
Authors: Tierny Julien , Vandeborre Jean‐Philippe , Daoudi Mohamed
Published: January 2009

This paper presents a novel approach for fast and efficient partial shape retrieval on a collection of 3D shapes. Each shape is represented by a Reeb graph associated with geometrical signatures. Partial similarity between two shapes is evaluated by computing a variant of their maximum common sub‐graph.

By investigating Reeb graph theory, we take advantage of its intrinsic properties at two levels. First, we show that the segmentation of a shape by a Reeb graph provides charts with disk or annulus topology only. This topology control enables the computation of concise and efficient sub‐part geometrical signatures based on parameterisation techniques. Secondly, we introduce the notion of Reeb pattern on a Reeb graph along with its structural signature. We show this information discards Reeb graph structural distortion and still depicts the topology of the related sub‐parts. The number of combinations to evaluate in the matching process is then dramatically reduced by only considering the combinations of topology equivalent Reeb patterns.

The proposed framework is invariant against rigid transformations and robust against non‐rigid transformations and surface noise. It queries the collection in interactive time (from 4 to 30 seconds for the largest queries). It outperforms the competing methods of the SHREC 2007 contest in term of NDCG vector and provides, respectively, a gain of 14.1% and 40.9% on the approaches by Biasotti et al.[BMSF06]and Cornea et al.[CDS*05].

As an application, we present an intelligent modelling‐by‐example system which enables a novice user to rapidly create new 3D shapes by composing shapes of a collection having similar sub‐parts.
Efficient Geometry Compression for GPU‐based Decoding in Realtime Terrain Rendering
Authors: Dick Christian , Schneider Jens , Westermann Rüdiger
Published: January 2009

We present a geometry compression scheme for restricted quadtree meshes and use this scheme for the compression of adaptively triangulated digital elevation models (DEMs). A compression factor of 8–9 is achieved by employing a generalized strip representation of quadtree meshes to incrementally encode vertex positions. In combination with adaptive error‐controlled triangulation, this allows us to significantly reduce bandwidth requirements in the rendering of large DEMs that have to be paged from disk. The compression scheme is specifically tailored for GPU‐based decoding, since it minimizes dependent memory access operations. We can thus trade CPU operations and CPU–GPU data transfer for GPU processing, resulting in twice faster streaming of DEMs from main memory into GPU memory. A novel storage format for decoded DEMs on the GPU facilitates a sustained rendering throughput of about 300 million triangles per second. Due to these properties, the proposed scheme enables scalable rendering with respect to the display resolution independent of the data size. For a maximum screen‐space error below 1 pixel it achieves frame rates of over 100 fps, even on high‐resolution displays. We validate the efficiency of the proposed method by presenting experimental results on scanned elevation models of several hundred gigabytes.
Networks of Attachment Relationships in Low‐income Children of Mexican Heritage: Infancy through Preschool
Authors: Howes Carollee , Wishard Guerra Alison G.
Published: January 2009

Eighty‐three low‐income Mexican‐heritage children (44 girls) and their mothers participated in this research. Children were observed with alternative caregivers at 14, 24, and 36 months of age using the Attachment Q‐Set. Most children received regular care from infancy through preschool from relatives and childcare providers. Children had high attachment security scores with both mothers and caregivers. Child–mother and child‐alternative caregiver attachment security scores were independent of each other. Children whose mothers did not participate in family clusters were lowest in child–mother attachment security at 14 months. More emotionally sensitive mothers and responsive alternative caregivers were associated with more secure child–adult attachments. Mothers who had more contact with relatives still in Mexico were more likely to have somewhat more positive relations between intrusive interaction and positive attachment relationships than mothers who had less contact.
Sharing the Cost of a Public Good without Subsidies
Authors: FLEURBAEY MARC , SPRUMONT YVES
Published: January 2009

We study the construction of a social ordering function for the case of a public good financed by contributions from the population. We extend the analysis of Maniquet and Sprumont (2004) to the case when cost shares cannot be negative, i.e., agents cannot receive subsidies from others. We adapt the Maniquet–Sprumont defense of public good welfare egalitarianism to this context. Weakening their Free Lunch Aversion axiom and adding a continuity requirement allows us to characterize the public good welfare maximin social ordering function.
Intermediate Preferences and Behavioral Conformity in Large Games
Authors: CARMONA GUILHERME
Published: January 2009

Motivated by Wooders, Cartwright, and Selten (2006), we consider games with a continuum of players and intermediate preferences. We show that any such game has a Nash equilibrium that induces a partition of the set of attributes into a bounded number of convex sets with the following property: all players with an attribute in the interior of the same element of the partition play the same action. We then use this result to show that all sufficiently large, equicontinuous games with intermediate preferences have an approximate equilibrium with the same property. Our result on behavior conformity for large finite game generalizes Theorem 3 of Wooders et al. (2006) by allowing both a wider class of preferences and a more general attribute space.
Repeated Contests with Asymmetric Information
Authors: MÜNSTER JOHANNES
Published: January 2009

The same contestants often meet repeatedly in contests. Behavior in a contest potentially provides information with regard to one's type and can therefore influence the behavior of the opponents in later contests. This paper shows that if effort is observable, this can induce a ratchet effect in contests: high ability contestants sometimes put in little effort in an early round in order to make the opponents believe that they are of little ability. The effect reduces overall effort and increases equilibrium utility of the contestants when compared with two unrelated one‐shot contests. It does, however, also introduce an allocative inefficiency since sometimes a contestant with a low valuation wins. The model assumes an imperfectly discriminating contest. In an extension I show that, qualitatively, results are similar in a perfectly discriminating contest (all pay auction).
Taxing Deficits to Restrain Government Spending
Authors: STÄHLER NIKOLAI
Published: January 2009

In a dynamic model of fiscal policy, social polarization provokes a deficit bias. Policy advisors have recently proposed that governments running a deficit should be forced to generate additional tax revenue. We show that this deficit taxation reduces each group's spending bias today because it decreases the fear that the financial resource will not be available tomorrow due to the other groups' spending behavior. This effect adds to the literature as previous findings focused mainly on the fact that deficit taxation reduces excessive spending because it increases the likelihood of politicians being voted out of office as the private sector dislikes taxation. In the present setup, the effect is driven solely by internalizing the externality exerted on tomorrow's spending potential.
Production and Abatement Distortions under Noisy Green Taxes
Authors: FENG HONGLI , HENNESSY DAVID A.
Published: January 2009

A pollution regulator seeking to maximize social surplus can be viewed as facing two efficiency problems. One is that, given abatement technology investment decisions, it should attempt to ensure that firms which should produce do produce and firms which should not produce do not produce. This ex‐post efficiency problem is not trivial when there is noise concerning the extent of environmental damage a firm does. We use a Bayesian information framework to show that the regulator may find it efficient to tax a firm that reads as a high (low) damage polluter at less (more) than the damage reading. Unfortunately when an abatement decision has to be made, this ex‐post efficient tax system also dampens the incentive to abate. In the absence of wrong‐firm concerns, a regulator can solve the abatement problem by an ex ante declaration that taxes will not be adjusted for signal noise. However, the regulator has a commitment problem as such taxes may not be ex‐post efficient. The most appropriate policy may involve a combination of instruments.
A Note on the Theme of Too Many Instruments*
Authors: Roodman David
Published: January 2009

The difference and system generalized method of moments (GMM) estimators are growing in popularity. As implemented in popular software, the estimators easily generate instruments that are numerous and, in system GMM, potentially suspect. A large instrument collection overfits endogenous variables even as it weakens the Hansen test of the instruments’ joint validity. This paper reviews the evidence on the effects of instrument proliferation, and describes and simulates simple ways to control it. It illustrates the dangers by replicating Forbes [American Economic Review (2000) Vol. 90, pp. 869–887] on income inequality and Levine et al. [Journal of Monetary Economics] (2000) Vol. 46, pp. 31–77] on financial sector development. Results in both papers appear driven by previously undetected endogeneity.
Merovingian partitions: a ‘genealogical charter’?
Authors: Widdowson Marc
Published: January 2009

This paper considers the classic accounts of Frankish partitions in 511 and 561 in light of the agenda of Gregory of Tours in the later 580s. While the partitions’ political origins have long been emphasized, the concern here is with the political motivations of the source on which we depend, almost exclusively, for our knowledge. This discussion questions whether there were ever actually definite agreements to divide the kingdom, and suggests claims about shared inheritance supplied a ‘genealogical charter’ that justified and deflected attention from the interests of people like Gregory, in what was a continuously contested, evolutionary process.
Pigs, presses and pastoralism: farming in the fifth to sixth centuries AD
Authors: Lewit Tamara
Published: January 2009

The fifth to sixth centuries were a time of significant change in rural settlement, land use, production levels and productive technology in many regions. Archaeological and related discoveries suggest that in western Europe, specialized market‐ and state‐oriented production gave way to mixed animal husbandry and diversified farming more suited to local terrains. This was accompanied by a widespread transformation of rural settlement. In contrast, the eastern Mediterranean experienced rural settlement expansion, intensification of land use, increased market‐oriented agricultural production, and a significant change in oil and wine press technology. These changes seem to reflect the socio‐political context in both east and west during this pivotal period.
Prevalence and Clinical Characteristics of Headache in Medical Students of the University of Lagos, Nigeria
Authors: Ojini FI , Okubadejo Nu , Danesi MA
Published: January 2009

We investigated the 1-year prevalence, clinical features and mode of treatment of headache in medical students of the University of Lagos, Nigeria, using a self-administered headache questionnaire. Headache prevalence was 46.0% and was significantly higher in women than in men (62.8% vs. 34.1%). Prevalence of tension-type headache was higher than that of migraine (18.1% vs. 6.4%). Although tension-type headache had a similar prevalence in both sexes (male 17.3%, female 19.2%), migraine was three times more common in women (10.9% vs. 3.2%). A family history of headache was present in 22.0%. Only 4.6% sought medical assistance, whereas 68.2% took non-prescription drugs, mainly simple analgesics. Specific drugs for migraine and tension-type headache were rarely used. In conclusion, 1-year headache prevalence is high among medical students at this university. The low consultation rate and the rarity of usage of specific anti-headache drugs probably reflect inadequacies in the management of primary headaches in this population.
Comparative studies of brain evolution: a critical insight from the Chiroptera
Authors: Dechmann Dina K. N , Safi Kamran
Published: January 2009

Comparative studies of brain size have a long history and contributed much to our understanding of the evolution and function of the brain and its parts. Recently, bats have been used increasingly as model organisms for such studies because of their large number of species, high diversity of life‐history strategies, and a comparatively detailed knowledge of their neuroanatomy. Here, we draw attention to inherent problems of comparative brain size studies, highlighting limitations but also suggesting alternative approaches. We argue that the complexity and diversity of neurological tasks that the brain and its functional regions (subdivisions) must solve cannot be explained by a single or few variables representing selective pressures. Using an example we show that by adding a single relevant variable, morphological adaptation to foraging strategy, to a previous analysis a correlation between brain and testes mass disappears completely and changes entirely the interpretation of the study. Future studies should not only look for novel determinants of brain size but also include known correlates in order to add to our current knowledge. We believe that comparisons at more detailed anatomical, taxonomic, and geographical levels will continue to contribute to our understanding of the function and evolution of mammalian brains.
Land crabs as key drivers in tropical coastal forest recruitment
Authors: Lindquist Erin Stewart , Krauss Ken W. , Green Peter T. , O’Dowd Dennis J. , Sherman Peter M. , Smith Thomas J.
Published: January 2009

Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems–mangroves, island maritime forests, and mainland coastal terrestrial forests–where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon‐rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size‐class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests.
Managing Multiple Risks: Use of a Concise Risk Assessment Format
Authors: Firth Hugh , Spanswick Mairi , Rutherford Linda
Published: January 2009

Risk management requires detailed understanding of circumstances affecting risk. Management of multiple risks necessitates different strategies to minimise different risks. Multi‐agency work requires presentation in accessible formats. Limitations of existing procedures are discussed. The Concise Risk Assessment Format summarises key information, differentiating history, risk and protective circumstances, and management recommendations/requirements for a number of either disparate or related types of risk. Standardised risk assessment information can be incorporated. The Format allows information to be readily contributed, shared, and updated between parents, young people and multiple agencies.
Investigating Business Schools' Intentions About Offering E‐Commerce Education Using an Extended Theory of Planned Behavior*
Authors: Dodor Jean Baptiste K. , Rana Dharam S.
Published: January 2009

This study investigates business schools' intentions about offering e‐commerce education (ECE) using an extended theory of planned behavior (ETPB). The need for an adequate match between future supply and demand of e‐commerce skills constitutes the main motivation for the study. The results show that most business schools consider ECE important for an adequate preparation of their students for today's competitive labor market. In addition, the proposed ETPB fits well the empirical data and predicts 65.2% of the variances in the schools' intentions about offering ECE. The results can help business schools in their curriculum decisions in at least two ways: (1) through the likely effect of social contagion and (2) through the constructs in the ETPB. First, institutional theory clearly indicates that organizations tend to adopt a new behavior when there is evidence that other organizations in their population have adopted or are likely to adopt that behavior. Having provided such evidence for ECE, this study is likely to promote the adoption of this educational product innovation. Second, the fact that the postulated ETPB fits well the empirical data suggests that administrators of business schools may pay attention to the key constructs when making curriculum decisions. Overall, the study has both theoretical and practical implications. Theoretically, it contributes to a growing literature on the adoption of innovative educational products like ECE. Practically, it provides valuable insights that administrators of business schools can use in their strategic curriculum decision making.
Proctored Versus Unproctored Online Exams: Studying the Impact of Exam Environment on Student Performance
Authors: Hollister Kimberly K. , Berenson Mark L.
Published: January 2009

Increasing numbers of universities are offering courses in online and hybrid formats. One challenge in online assessment is the maintenance of academic integrity. We present a thorough statistical analysis to uncover differences in student performance when online exams are administered in a proctored environment (i.e., in class) versus an unproctored environment (i.e., offsite). Controlling for student grade point average (GPA), no significant differences in mean overall course performance or exam performance between the two groups were found, nor were there any differences in the mean vectors of individual exam scores. The study reveals that the group taking online exams in the unproctored environment has significantly more variation in their performance results. In examining potential causes of the greater variation, analyses were performed to assess whether an increased level of possible cheating behavior could be observed from performance results for students in the unproctored section. No evidence of cheating behavior was found.
Postural Tachycardia Syndrome (POTS)
Authors: LOW PHILLIP A. , SANDRONI PAOLA , JOYNER MICHAEL , SHEN WIN‐KUANG
Published: January 2009

Postural Tachycardia Syndrome. Introduction: POTS is defined as the development of orthostatic symptoms associated with a heart rate (HR) increment ≥30, usually to ≥120 bpm without orthostatic hypotension. Symptoms of orthostatic intolerance are those due to brain hypoperfusion and those due to sympathetic overaction.

Methods:
We provide a review of POTS based primarily on work from the Mayo Clinic.

Results:
Females predominate over males by 5:1. Mean age of onset in adults is about 30 years and most patients are between the ages of 20–40 years. Pathophysiologic mechanisms (not mutually exclusive) include peripheral denervation, hypovolemia, venous pooling, β‐receptor supersensitivity, psychologic mechanisms, and presumed impairment of brain stem regulation. Prolonged deconditioning may also interact with these mechanisms to exacerbate symptoms. The evaluation of POTS requires a focused history and examination, followed by tests that should include HUT, some estimation of volume status and preferably some evaluation of peripheral denervation and hyperadrenergic state. All patients with POTS require a high salt diet, copious fluids, and postural training. Many require β‐receptor antagonists in small doses and low‐dose vasoconstrictors. Somatic hypervigilance and psychologic factors are involved in a significant proportion of patients.

Conclusions:
POTS is heterogeneous in presentation and mechanisms. Major mechanisms are denervation, hypovolemia, deconditioning, and hyperadrenergic state. Most patients can benefit from a pathophysiologically based regimen of management. (J Cardiovasc Electrophysiol, Vol. 20, pp. 352‐358, March 2009)
Clinical Significance of Complete Conduction Block of the Left Lateral Isthmus and Its Relationship with Anatomical Variation of the Vein of Marshall in Patients with Nonparoxysmal Atrial Fibrillation
Authors: CHOI JONG‐IL , PAK HUI‐NAM , PARK JAE HYUNG , CHOI EUN JEONG , KIM SOOK KYOUNG , KWAK JAE JIN , JANG JIN KUN , HWANG CHUN , KIM YOUNG‐HOON
Published: January 2009

Background: The vein of Marshall (VOM), which exists along the left lateral isthmus (LLI), constitutes a muscular connection between the coronary sinus (CS) and the left atrium (LA). We hypothesized that anatomical variation of the VOM affects the bidirectional block of LLI and the clinical outcome in patients with nonparoxysmal atrial fibrillation (NPAF).

Methods: Among 73 patients with NPAF, 54 patients (47 male, 54.1 ± 10.4 years old) with a clearly visible VOM (74.0%) were included. After circumferential antral ablation, double linear endocardial ablation of LLI was performed along the VOM. Unless LLI block was achievable by endocardial ablation, the ablation was performed inside the CS.

Results: LLI block was achievable in 35 patients (64.8%; 11.1% by endocardial ablation vs 53.7% by additional inside CS ablation; P < 0.01). In patients with failed LLI block, the VOM was significantly longer (P < 0.05) on the right anterior oblique (RAO) view than in those with successful LLI block. LA volume or LLI length measured by CT image were not different (P = NS). During 11.4 ± 5.0 months follow‐up, early recurrences within 3 months (47.4% vs 28.6%, P = NS) and recurrences after 3 months (10.5% vs 17.7%, P = NS) were not different with or without LLI block.

Conclusion: LLI block, which is more difficult to achieve in patients with a longer VOM, was achievable in 65% of patients with NPAF by linear ablation along the VOM and additional inside CS ablation, but did not affect the short‐term clinical outcome.