On the Behaviour of Marginal and Conditional Akaike Information Criteria in Linear Mixed Models

In linear mixed models, model selection frequently includes the selection of random effects. Two versions of the Akaike information criterion (AIC) have been used, based either on the marginal or on the conditional distribution. We show that the marginal AIC is no longer an asymptotically unbiased estimator of the Akaike information, and in fact favours smaller models without random effects. For the conditional AIC, we show that ignoring estimation uncertainty in the random effects covariance matrix, as is common practice, induces a bias that leads to the selection of any random effect not predicted to be exactly zero. We derive an analytic representation of a corrected version of the conditional AIC, which avoids the high computational cost and imprecision of available numerical approximations. An implementation in an R package is provided. All theoretical results are illustrated in simulation studies, and their impact in practice is investigated in an analysis of childhood malnutrition in Zambia.

Do charges to freight trucks and trains in the European Union reflect their social marginal costs? Application to the case of Spain

In the last few years, the European Union (EU) has become greatly concerned about the environmental costs of road transport in Europe as a result of the constant growth in the market share of trucks and the steady decline in the market share of railroads. In order to reverse this trend, the EU is promoting the implementation of additional charges for heavy goods vehicles (HGV) on the trunk roads of the EU countries. However, the EU policy is being criticised because it does not address the implementation of charges to internalise the external costs produced by automobiles and other transport modes such as railroad. In this paper, we first describe the evolution of the HGV charging policy in the EU, and then assess its practical implementation across different European countries. Second, and of greater significance, by using the case study of Spain, we evaluate to what extent the current fees on trucks and trains reflect their social marginal costs, and consequently lead to an allocative-efficient outcome. We found that for the average case in Spain the truck industry meets more of the marginal social cost produced by it than does the freight railroad industry. The reason for this lies in the large sums of money paid by truck companies in fuel taxes, and the subsidies that continue to be granted by the government to the railroads.

Cost-effectiveness of Transcatheter Mitral Valve Leaflet Repair for the Treatment of Mitral Regurgitation in Heart Failure

Contexte: La régurgitation mitrale (RM) est une maladie valvulaire nécessitant une intervention dans les cas les plus grave. Une réparation percutanée de la valve mitrale avec le dispositif MitraClip est un traitement sécuritaire et efficace pour les patients à haut risque chirurgical. Nous voulons évaluer les résultats cliniques et l'impact économique de cette thérapie par rapport à la gestion médicale des patients en insuffisance cardiaque avec insuffisance mitrale symptomatique. Méthodes: L'étude a été composée de deux phases; une étude d'observation de patients souffrant d'insuffisance cardiaque et de régurgitation mitrale traitée avec une thérapie médicale ou le MitraClip, et un modèle économique. Les résultats de l'étude observationnelle ont été utilisés pour estimer les paramètres du modèle de décision, qui a estimé les coûts et les avantages d'une cohorte hypothétique de patients atteints d'insuffisance cardiaque et insuffisance mitrale sévère traitée avec soit un traitement médical standard ou MitraClip. Résultats: La cohorte de patients traités avec le système MitraClip était appariée par score de propension à une population de patients atteints d'insuffisance cardiaque, et leurs résultats ont été comparés. Avec un suivi moyen de 22 mois, la mortalité était de 21% dans la cohorte MitraClip et de 42% dans la cohorte de gestion médicale (p = 0,007). Le modèle de décision a démontré que MitraClip augmente l'espérance de vie de 1,87 à 3,60 années et des années de vie pondérées par la qualité (QALY) de 1,13 à 2,76 ans. Le coût marginal était 52.500 $ dollars canadiens, correspondant à un rapport coût-efficacité différentiel (RCED) de 32,300.00 $ par QALY gagné. Les résultats étaient sensibles à l'avantage de survie. Conclusion: Dans cette cohorte de patients atteints d'insuffisance cardiaque symptomatique et d insuffisance mitrale significative, la thérapie avec le MitraClip est associée à une survie supérieure et est rentable par rapport au traitement médical.

Cost-Benefit Analysis of Climate Change (a Methodological Overview of Recent Studies)

This paper examines the methodological aspect of climate change, particularly the aggregation of costs and benefits induced by climate change on individuals, societies, economies and on the whole ecosystem. Assessing the total and/or marginal costs of environmental change is difficult because of wide range of factors that have to be involved. The subsequent study tries to capture the complexity of cost assessment on climate change therefore includes several critical factors such as scenarios and modeling, valuation and estimation, equity and discounting.

Leading from the Edge: Marginal Leadership at Cultural Crossroads

If a church reflects its larger community, it will have more dynamic interactions among different people. Current U.S. communities consist of very diverse people who have different socioeconomic and cultural backgrounds. Since the mid 20th century, various immigrant communities who have dissimilar cultural, religious, and linguistic traditions have accelerated the need of change in American churches. The drastic cultural change has demanded churches to equip their lay and clergy leaders with multicultural competencies for effective ministries.

My thesis explores imaginative leadership in cultural crossroads. Emphasizing the leadership imagination of cross-cultural ministry, I approach it in biblical, theological, and missional perspectives. In this dynamic cultural milieu, the study topic may help the church renew its ecclesial purpose by seeing cross-cultural ministry as a creative opportunity to reach out to more diverse people of God. I begin with a conceptual framework for cross-cultural ministry and cultural intelligence. Then I explain why cross-cultural ministry is significant and how it enhances the spirit of Christ Jesus. As I develop the thesis, I discuss leadership challenge and development in the cross-cultural ministry context. This thesis may contribute to equipping lay and clergy leaders by overcoming the homogeneous ‘in-group’ mindset in the church.

The primary focus is on developing marginal leadership of church in the post-Christendom era. Church leaders must creatively hold the tension between the current church context and Christian faith resources and seek a hopeful resolution as a third way through integrative thought process. While conventional leadership emphasizes a better choice out of the given options, marginal leadership takes time for integrative thought process to seek a new direction for the future. Conventional leaders take the center with their power, status, and prestige, but marginal leaders position themselves on the edge. Leading from the edge is a distinctive cross-cultural leadership and is based on the servant leadership of Jesus Christ who put himself as a servant for the marginalized. By serving and relating to others on the margin, this imaginative leadership may make appropriate changes desired in today’s American churches.

In addition to academic research, I looked into the realities of cross-cultural leadership in the local churches through congregational studies. I speculated that church leadership involves both laity and clergy and that it can be enhanced. All Christians are called to serve the Lord according to their gifts, and it is crucial for lay and clergy persons to develop their leadership character and skills. In particular, as humans are contextualized with their own cultures, church leaders often confront great challenges in cross-cultural or multicultural situations. Through critical thoughts and imaginative leadership strategies, however, they can overcome intrinsic human prejudice and obstacles.

Through the thesis project, I have reached four significant conclusions. First, cultural intelligence is an essential leadership capacity for all church leaders. As the church consists of more diverse cultural people today, its leaders need to have cultural competencies. In particular, cross-cultural leaders must be equipped with cultural intelligence. Cross-cultural ministry is not a simple byproduct of social change, but a creative strategy to open a door to bring God’s reconciliation among diverse people. Accordingly, church leaders are to be well prepared to effectively cope with the challenges of cultural interactions. Second, both lay and clergy leaders’ imaginative leadership is crucial for leading the congregation. While conventional leadership puts an emphasis on selecting a better choice based on the principle of opportunity cost, imaginative leaders critically consider the present church situations and Christian faith values together in integrative thoughts and pursue a third way as the congregation’s future hope. Third, cross-cultural leadership has a unique characteristic of leading from the edge and promotes God’s justice and peaceable relationships among different people. By leading the congregation from the edge, church leaders may experience the heart of Christ Jesus who became the friend of the marginalized. Fourth, the ‘homogeneous unit principle’ theory has its limit for today’s complex ‘inter-group’ community context. The church must be a welcoming and embracing faith community for all people. Cross-cultural ministry may become an entrance door for a more peaceable and reconciling life among different people. By building solidarity with others, the church may experience a kingdom reality.

This thesis focuses on the mission of the church and marginal leadership of church leaders in ever-changing cultural crossroads. The church becomes a hope in the broken and apathetic world, and Christians are called to build relationships inside and beyond the church. It is significant for church leaders to be faithfully present on the margin and relate to diverse people. By consistently positioning themselves on the margin, they can build relationships with new and diverse people and shape a faithful life pattern for others.

On the Cost of Using Happy Eyeballs for Transport Protocol Selection

Concerns have been raised in the past several years that introducing new transport protocols on the Internet has be- come increasingly difficult, not least because there is no agreed-upon way for a source end host to find out if a trans- port protocol is supported all the way to a destination peer. A solution to a similar problem—finding out support for IPv6—has been proposed and is currently being deployed: the Happy Eyeballs (HE) mechanism. HE has also been proposed as an efficient way for an application to select an appropriate transport protocol. Still, there are few, if any, performance evaluations of transport HE. This paper demonstrates that transport HE could indeed be a feasible solution to the transport support problem. The paper evaluates HE between TCP and SCTP using TLS encrypted and unencrypted traffic, and shows that although there is indeed a cost in terms of CPU load to introduce HE, the cost is rel- atively small, especially in comparison with the cost of using TLS encryption. Moreover, our results suggest that HE has a marginal impact on memory usage. Finally, by introduc- ing caching of previous connection attempts, the additional cost of transport HE could be significantly reduced. 

Effect of deproteinization and tubular occlusion on microtensile bond strength and marginal microleakage of resin composite restorations

Dentin adhesion procedure presents limitations, especially regarding to lifetime stability of formed hybrid layer. Alternative procedures have been studied in order to improve adhesion to dentin. OBJECTIVE: The aim of this study was to evaluate in vitro the influence of deproteinization or dentin tubular occlusion, as well as the combination of both techniques, on microtensile bond strength (µTBS) and marginal microleakage of composite resin restorations. MATERIAL AND METHODS: Extracted erupted human third molars were randomly divided into 4 groups. Dentin surfaces were treated with one of the following procedures: (A) 35% phosphoric acid gel (PA) + adhesive system (AS); (B) PA + 10% NaOCl + AS; (C) PA + oxalate + AS and (D) PA + oxalate + 10% NaOCl + AS. Bond strength data were analyzed statistically by two-way ANOVA and Tukey's test. The microleakage scores were analyzed using Kruskal-Wallis and Mann-Whitney non-parametric tests. Significance level was set at 0.05 for all analyses. RESULTS: µTBS data presented statistically lower values for groups D and B, ranking data as A>C>B>D. The use of oxalic acid resulted in microleakage reduction along the tooth/restoration interface, being significant when used alone. On the other hand, the use of 10% NaOCl alone or in combination with oxalic acid, resulted in increased microleakage. CONCLUSIONS: Dentin deproteinization with 10% NaOCl or in combination with oxalate significantly compromised both the adhesive bond strength and the microleakage at interface. Tubular occlusion prior to adhesive system application seems to be a useful technique to reduce marginal microleakage.

Influence of light-curing unit systems on shear bond strength and marginal microleakage of composite resin restorations

The aim of the present study was to evaluate the influence of different photopolymerization (halogen, halogen soft-start and LED) systems on shear bond strength (SBS) and marginal microleakage of composite resin restorations. Forty Class V cavities (enamel and dentin margins) were prepared for microleakage assessment, and 160 enamel and dentin fragments were prepared for the SBS test, and divided into 4 groups. Kruskal-Wallis and Wilcoxon tests showed statistically significant difference in microleakage between the margins (p < 0.01) with incisal margins presenting the lowest values. Among the groups, it was observed that, only at the cervical margin, halogen soft-start photo polymerization presented statistically significant higher microleakage values. For SBS test, ANOVA showed no statistical difference (p > 0.05) neither between substrates nor among groups. It was concluded that Soft-Start technique with high intensity end-light influenced negatively the cervical marginal sealing, but the light-curing systems did not influence adhesion.

Short-term triple therapy with azithromycin for Helicobacter pylori eradication: Low cost, high compliance, but low efficacy

Background: The Brazilian consensus recommends a short-term treatment course with clarithromycin, amoxicillin and proton-pump inhibitor for the eradication of Helicobacter pylori ( H. pylori). This treatment course has good efficacy, but cannot be afforded by a large part of the population. Azithromycin, amoxicillin and omeprazole are subsidized, for several aims, by the Brazilian federal government. Therefore, a short-term treatment course that uses these drugs is a low-cost one, but its efficacy regarding the bacterium eradication is yet to be demonstrated. The study's purpose was to verify the efficacy of H. pylori eradication in infected patients who presented peptic ulcer disease, using the association of azithromycin, amoxicillin and omeprazole. Methods: Sixty patients with peptic ulcer diagnosed by upper digestive endoscopy and H. pylori infection documented by rapid urease test, histological analysis and urea breath test were treated for six days with a combination of azithromycin 500 mg and omeprazole 20 mg, in a single daily dose, associated with amoxicillin 500 mg 3 times a day. The eradication control was carried out 12 weeks after the treatment by means of the same diagnostic tests. The eradication rates were calculated with 95% confidence interval. Results: The eradication rate was 38% per intention to treat and 41% per protocol. Few adverse effects were observed and treatment compliance was high. Conclusion: Despite its low cost and high compliance, the low eradication rate does not allow the recommendation of the triple therapy with azithromycin as an adequate treatment for H. pylori infection.

Cost risk benefit analysis to support chemoprophylaxis policy for travellers to malaria endemic countries

Background: In a number of malaria endemic regions, tourists and travellers face a declining risk of travel associated malaria, in part due to successful malaria control. Many millions of visitors to these regions are recommended, via national and international policy, to use chemoprophylaxis which has a well recognized morbidity profile. To evaluate whether current malaria chemo-prophylactic policy for travellers is cost effective when adjusted for endemic transmission risk and duration of exposure. a framework, based on partial cost-benefit analysis was used Methods: Using a three component model combining a probability component, a cost component and a malaria risk component, the study estimated health costs avoided through use of chemoprophylaxis and costs of disease prevention (including adverse events and pre-travel advice for visits to five popular high and low malaria endemic regions) and malaria transmission risk using imported malaria cases and numbers of travellers to malarious countries. By calculating the minimal threshold malaria risk below which the economic costs of chemoprophylaxis are greater than the avoided health costs we were able to identify the point at which chemoprophylaxis would be economically rational. Results: The threshold incidence at which malaria chemoprophylaxis policy becomes cost effective for UK travellers is an accumulated risk of 1.13% assuming a given set of cost parameters. The period a travellers need to remain exposed to achieve this accumulated risk varied from 30 to more than 365 days, depending on the regions intensity of malaria transmission. Conclusions: The cost-benefit analysis identified that chemoprophylaxis use was not a cost-effective policy for travellers to Thailand or the Amazon region of Brazil, but was cost-effective for travel to West Africa and for those staying longer than 45 days in India and Indonesia.

Cost-effectiveness analysis of PCR for the rapid diagnosis of pulmonary tuberculosis

Background: Tuberculosis is one of the most prominent health problems in the world, causing 1.75 million deaths each year. Rapid clinical diagnosis is important in patients who have comorbidities such as Human Immunodeficiency Virus (HIV) infection. Direct microscopy has low sensitivity and culture takes 3 to 6 weeks [1-3]. Therefore, new tools for TB diagnosis are necessary, especially in health settings with a high prevalence of HIV/TB co-infection. Methods: In a public reference TB/HIV hospital in Brazil, we compared the cost-effectiveness of diagnostic strategies for diagnosis of pulmonary TB: Acid fast bacilli smear microscopy by Ziehl-Neelsen staining (AFB smear) plus culture and AFB smear plus colorimetric test (PCR dot-blot). From May 2003 to May 2004, sputum was collected consecutively from PTB suspects attending the Parthenon Reference Hospital. Sputum samples were examined by AFB smear, culture, and PCR dot-blot. The gold standard was a positive culture combined with the definition of clinical PTB. Cost analysis included health services and patient costs. Results: The AFB smear plus PCR dot-blot require the lowest laboratory investment for equipment (US$ 20,000). The total screening costs are 3.8 times for AFB smear plus culture versus for AFB smear plus PCR dot blot costs (US$ 5,635,760 versus US$ 1,498, 660). Costs per correctly diagnosed case were US$ 50,773 and US$ 13,749 for AFB smear plus culture and AFB smear plus PCR dot-blot, respectively. AFB smear plus PCR dot-blot was more cost-effective than AFB smear plus culture, when the cost of treating all correctly diagnosed cases was considered. The cost of returning patients, which are not treated due to a negative result, to the health service, was higher in AFB smear plus culture than for AFB smear plus PCR dot-blot, US$ 374,778,045 and US$ 110,849,055, respectively. Conclusion: AFB smear associated with PCR dot-blot associated has the potential to be a cost-effective tool in the fight against PTB for patients attended in the TB/HIV reference hospital.

Cost effectiveness of OptiMal (R) rapid diagnostic test for malaria in remote areas of the Amazon Region, Brazil

Background: In areas with limited structure in place for microscopy diagnosis, rapid diagnostic tests (RDT) have been demonstrated to be effective. Method: The cost-effectiveness of the Optimal (R) and thick smear microscopy was estimated and compared. Data were collected on remote areas of 12 municipalities in the Brazilian Amazon. Data sources included the National Malaria Control Programme of the Ministry of Health, the National Healthcare System reimbursement table, hospitalization records, primary data collected from the municipalities, and scientific literature. The perspective was that of the Brazilian public health system, the analytical horizon was from the start of fever until the diagnostic results provided to patient and the temporal reference was that of year 2006. The results were expressed in costs per adequately diagnosed cases in 2006 U. S. dollars. Sensitivity analysis was performed considering key model parameters. Results: In the case base scenario, considering 92% and 95% sensitivity for thick smear microscopy to Plasmodium falciparum and Plasmodium vivax, respectively, and 100% specificity for both species, thick smear microscopy is more costly and more effective, with an incremental cost estimated at US$ 549.9 per adequately diagnosed case. In sensitivity analysis, when sensitivity and specificity of microscopy for P. vivax were 0.90 and 0.98, respectively, and when its sensitivity for P. falciparum was 0.83, the RDT was more cost-effective than microscopy. Conclusion: Microscopy is more cost-effective than OptiMal (R) in these remote areas if high accuracy of microscopy is maintained in the field. Decision regarding use of rapid tests for diagnosis of malaria in these areas depends on current microscopy accuracy in the field.

Cost-effectiveness of Sick Leave Policies for Health Care Workers with Influenza-like Illness, Brazil, 2009

We describe the effect of influenza-like illness (ILI) during the outbreak of pandemic (H1N1) 2009 on health care worker (HCW) absenteeism and compare the effectiveness and cost of 2 sick leave policies for HCWs with suspected influenza. We assessed initial 2-day sick leaves plus reassessment until the HOW was asymptomatic (2-day + reassessment policy), and initial 7-day sick leaves (7-day policy). Sick leaves peaked in August 2009: 3% of the workforce received leave for ILI. Costs during May October reached R$798,051.87 (approximate to US $443,362). The 7-day policy led to a higher monthly rate of sick leave days per 100 HCWs than did the 2-day + reassessment policy (8.72 vs. 3.47 days/100 HCWs; p<0.0001) and resulted in higher costs (US $609 vs. US $1,128 per HCW on leave). ILI affected HCW absenteeism. The 7-day policy was more costly and not more effective in preventing transmission to patients than the 2-day + reassessment policy.

A Cost-Benefit Analysis on Modulation Formats for 40-Gb/s Optical Communication Systems

This article discusses possible approaches for optical network capacity upgrade by considering the use of different modulation formats at 40 Gb/s. First, a performance evaluation is carried out regarding tolerance to three impairments: spectral narrowing due to filter cascading, chromatic dispersion, and self-phase modulation. Next, a cost-benefit analysis is conducted, considering the specific optoelectronic components required for the optical transmitter/receiver configuration of each format.

Rotifer abundance, biomass, and secondary production after the recovery of hydrologic connectivity between a river and two marginal lakes (Sao Paulo, Brazil)

Rotifera density, biomass, and secondary production on two marginal lakes of Paranapanema River were compared after the recovery of hydrologic connectivity with the river (Sao Paulo State, Brazil). Daily samplings were performed in limnetic zone of both lakes during the rainy season immediately after lateral inflow of water and, in the dry period, six months after hydrologic connectivity recovery. In order to identify the factors that affect rotifer population dynamics, lake water level, volume, depth, temperature, transparency, dissolved oxygen, pH, alkalinity, conductivity, suspended solids, nutrients, and chlorophyll-a were determined. Variations of water physical and chemical factors that affect rotifer population were related to the lake-river degree of connection and to water level rising after drought. The water lateral inflow from the river resulted in an increase in lake water volume, depth, and transparency and a decrease in water pH, alkalinity, and suspended solids. The lake with the wider river connection, more frequent biota exchange, and larger amount of particulate and dissolved materials was richer and more diverse, while rotifer density, biomass, and productivity were lower in both periods studied. Density, biomass, and secondary production were higher in the lake with the smaller river connection and the higher physical and chemical stability. Our results show that the connectivity affects the limnological stability, associated to seasonality. Stable conditions, caused by low connectivity in dry periods, were related with high density, biomass and secondary production. Conversely, instability conditions in rainy periods were associated to elevated richness and diversity values, caused by exchange biota due to higher connectivity. (C) 2008 Elsevier GmbH. All rights reserved.