bluuebunny/crossref_metadata_2025 huggingface dataset:
Grade‐Risk: An Insurable Event in the Classroom
Authors: Pope Nat , Ma Yu‐Luen
Published: October 2004

Abstract

Grade‐risk provides a powerful ally in establishing relevance between course content and the lives of students. As used in this article, grade‐risk refers to the potential for the loss of points on examinations, quizzes, etc. This article describes the rationale and feasibility associated with the introduction of a student‐centered grade insurance project that provides some measure of protection against grade‐risk. The project engages students on multiple levels and in various capacities resulting in a significantly enriched learning experience. The authors include examples employed in their own classroom in demonstrating the feasibility and validity of grade insurance as a learning tool.
Applicability of a monoclonal antibody‐based dipstick in diagnosis of urinary schistosomiasis in the Central Region of Ghana
Authors: Bosompem Kwabena M. , Owusu Osei , Okanla E. O. , Kojima Somei
Published: October 2004

We tested a rapid visually read monoclonal antibody (MoAb) based dipstick assay for specific diagnosis of urinary schistosomiasis against microscopy and the use of haematuria and proteinuria in a schistosomiasis haematobia endemic area in the Central Region of Ghana. The study group consisted of 141 school children (83 males, 58 females) aged 8–19 years. A total of 129 of 141 (91.5%) submitted stool samples, and 7.8% had Schistosoma mansoni, 55% had hookworms and 6.2% had tapeworms. The presence of S. mansoni and intestinal parasites did not appear to influence the results of the MoAb‐dipstick assay. The urinary schistosomiasis prevalence by MoAb‐dipstick (78%) was higher (P < 0.05) than the estimate by microscopy (60.3%), microhaematuria (27%) and proteinuria (30.5%). The MoAb‐dipstick correctly identified 98.8% of microscopically confirmed cases and missed one (1.3%). The dipstick was also positive for 26 of 56 (46.4%) egg‐negative individuals, thereby giving a sensitivity of 98.8% and a specificity of 53.6%. On the other hand, microhaematuria and proteinuria were 38.8% and 30.6% sensitive, and 91.1% and 69.6% specific, respectively. Microhaematuria and proteinuria were less sensitive (P < 0.05) than both microscopy and MoAb‐dipstick.
The difference between effectiveness and efficacy of antimalarial drugs in Kenya
Authors: Amin Abdinasir A. , Hughes Dyfrig A. , Marsh Vicki , Abuya Timothy O. , Kokwaro Gilbert O. , Winstanley Peter A. , Ochola Sam A. , Snow Robert W.
Published: October 2004

Objective  To demonstrate the difference between effectiveness and efficacy of antimalarial (AM) drugs in Kenya.

Methods  We undertook a series of linked surveys in four districts of Kenya between 2001 and 2002 on (i) community usage of nationally recommended first‐ and second‐line AM drugs; (ii) commonly stocked AM products in the retail and wholesale sectors; and (iii) quality of the most commonly available first‐ and second‐line AM products. These were combined with estimates of adherence and clinical efficacy to derive overall drug effectiveness.

Results  The overall modelled effectiveness for sulphadoxine–pyrimethamine (SP) was estimated to be 62% compared with 85% for reported SP clinical efficacy. For amodiaquine the modelled effectiveness was 48% compared with 99% reported efficacy during the same time period.

Conclusions  The quality of AM products and patient adherence to dosage regimens are important determinants of drug effectiveness, and should be measured alongside clinical efficacy. Post‐registration measures to regulate drug quality and improve patient adherence would contribute significantly to AM drug performance.
Artemisinin‐based combination therapy reduces expenditure on malaria treatment in KwaZulu Natal, South Africa
Authors: Muheki Charlotte , McIntyre Di , Barnes Karen I.
Published: October 2004

Introduction  There is growing international evidence that artemisinin‐based combination therapy (ACT) is one of the few effective measures available to ‘Roll Back Malaria’. However, concerns about the costs and affordability of ACT are obstacles to its widespread implementation. This paper explores some economic aspects of the implementation of artemether–lumefantrine (AL) to replace sulphadoxine–pyrimethamine (SP) in the KwaZulu Natal (KZN) province, South Africa.

Methods  Recurrent and capital costs for malaria treatment were compared at baseline and post‐intervention for nine clinics and a sentinel rural district hospital. Changes in the unit costs of, and total expenditure on, malaria services were calculated and the cost effectiveness of AL relative to SP was assessed.

Results  The number of outpatient malaria cases and inpatient admissions both declined by 94% between 2000 and 2002. After accounting for the role of concurrent improvements in vector control, it was conservatively estimated that 36% of the decline in outpatient cases and 46% for inpatient admissions was attributable to changing the first‐line drug to AL. Although AL is considerably more expensive than SP, its improved cure rate and reduced malaria transmission resulted in an estimated US$ 201 065 cost saving in 2002 alone for the subdistrict studied.

Discussion  In the context of effective vector control and low efficacy of existing monotherapy, ACT can reduce total expenditure on malaria services. However, the relevance of these findings requires careful consideration in countries with currently effective treatment policies and higher intensity malaria transmission.
An outbreak of leptospirosis in Orissa, India: the importance of surveillance
Authors: Jena Abani Bhusan , Mohanty Kailash C. , Devadasan N.
Published: October 2004

Objective  To demonstrate the importance of surveillance systems in detecting emerging diseases and highlighting the strengths and weaknesses of an existing one.

Methods  The Orissa multi‐disease surveillance system (OMDSS) was introduced in November 1999. Reporting units from the periphery send data to the district on a weekly basis. These reports are analysed regularly. A district task force (DTF) was available to intervene in the event of an outbreak. The OMDSS detected an increasing number of cases with fever and jaundice in June 2002. The DTF investigated this outbreak using clinical, epidemiological and laboratory tools to identify its cause.

Results  This outbreak, in a remote corner of India, was detected within 4 days by an existing surveillance system. Action was initiated within 24 h, but it took approximately two more weeks for the causative agent to be diagnosed. A total of 143 people were suspected to have leptospirosis between 23 June 2002 and 31 July 2002. The attack rate was 5.95% and the case fatality ratio (CFR) was 7.69%, both lower than outbreaks reported elsewhere in India. While males were infected more often than females, the CFR was higher among females and among the 6–15 year age groups. Exposure to infected water in a canal was the probable cause of the outbreak. IgM antibodies were positive in 33 of the patients and six patients tested positive for PCR and culture. Leptospirosis interrogans serovar canicola, Leptospirosis interrogans serovar pomona and Leptospirosis interrogans serovar hebdomadis were isolated.

Conclusions  Leptospirosis is a new disease in this region of India. This outbreak was detected and diagnosed because of the surveillance system. The prompt response helped in containing the outbreak early enough. However, the morbidity and mortality could have been further mitigated if the delays in transmitting information had been minimized. An adequate laboratory support would have also helped considerably. We conclude stressing the importance of surveillance as a public health tool.
Anti‐leishmanial activity of a new formulation of amphotericin B
Authors: Dea‐Ayuela M. A. , Rama‐Íñiguez S. , Sánchez‐Brunete J. A. , Torrado J. J. , Alunda J. M. , Bolás‐Fernández F.
Published: October 2004

The effectiveness of albumin microspheres loaded with amphotericin B was tested in an in vivo model of visceral leishmaniasis using the golden hamster. Free and encapsulated amphotericin B was tested at the dose of 1 mg/kg given by the intracardiac route on days 25, 26 and 27 post‐infection (p.i.) to treat animals previously infected with 107 stationary promastigotes by the intracardiac route. Encapsulated amphotericin was highly effective against infection causing a reduction of 88.8% and 87.2% in the early stage of infection (day 32 p.i.) and of 66.7% and 54% in a later stage of infection (day 135 p.i.) in liver and spleen parasite load respectively, compared with untreated animals, whereas free amphotericin was inactive. Lymphocyte proliferation was restored together with an increase in CD4+ subsets in animals treated with encapsulated amphotericin B, but not in those treated with the non‐encapsulated compound. Antibody responses did not increase after treatment with encapsulated amphotericin B with antibody levels remaining at base levels for most animals in contrast to those of untreated or treated with free amphotericin, where in most animals the antibody levels sharply increased. This new formulation could be a more economical alternative to liposomes for the treatment of visceral leishmaniasis with amphotericin B.
Effectiveness of two annual, single‐dose mass drug administrations of diethylcarbamazine alone or in combination with albendazole on soil‐transmitted helminthiasis in filariasis elimination programme
Authors: Mani T. R. , Rajendran R. , Sunish I. P. , Munirathinam A. , Arunachalam N. , Satyanarayana K. , Dash A. P.
Published: October 2004

A longitudinal community‐trial on the control of soil‐transmitted helminths (STHs), as part of a lymphatic filariasis elimination campaign, was taken up in two revenue blocks of southern India in the years 2001 and 2002 to assess the impact of two annual single‐dose mass drug administration (MDA) of diethylcarbamazine (DEC) + albendazole (ALB) with that of DEC alone. The prevalences and intensities of STHs were studied among cross‐sectional samples of school children aged 9–10 years by using the Kato‐Katz technique at baseline and 11 months after each MDA. The combined drug mass treatment produced a higher reduction in the prevalence (RIP) (51–77%) and the egg reduction rate (ERR) (92–98%) compared with 12–15% RIP and 58–62% ERR of DEC alone mass treatment. The effect of two‐drug therapy after two annual treatments was relatively long lasting as shown by RIP and ERR indicating that the reinfection rates were relatively lower in this approach than single‐drug therapy. This study demonstrates that mass drug co‐administration of DEC + ALB in Global Programme for Elimination of Lymphatic Filariasis (GPELF) targeted at the community had a synergistic and sustainable effect against soil‐transmitted helminthiasis and provided considerable ‘beyond filariasis’ benefits. The additional advantages accrued to the community underscore the importance of scaling‐up GPELF to cover the entire population at risk.
Helicobacter pylori antigens in the faeces of asymptomatic children in the Buea and Limbe health districts of Cameroon: a pilot study
Authors: Ndip R. N. , Malange A. E. , Akoachere J. F. T. , MacKay W. G. , Titanji V. P. K. , Weaver L. T.
Published: October 2004

Objective  To determine the prevalence and identify intra‐familial risk factors associated with Helicobacter pylori infection in a paediatric population.

Methods  Cross‐sectional study in the Buea and Limbe health districts, South West Cameroon. Stool samples were collected from 176 randomly selected apparently healthy children from two communities with different socioeconomic status. They comprised 86 males and 90 females aged 0–10 years with a mean age of 4.29. Helicobacter pylori status was determined using an enzyme‐linked immunosorbent assay, the H. pylori stool antigen (HpSA) test. The test uses polyclonal anti‐H. pylori capture antibody to detect H. pylori antigens in human stool. Epidemiological data were analysed using the Fisher test and odds ratio (OR) at 95% confidence intervals (CI).

Results  The overall prevalence of H. pylori was 52.27% (92 of 176). Univariate analysis showed that H. pylori prevalence was significantly higher in children of the low socioeconomic class, 62.50% (55 of 88) than in those of the high socioeconomic class, 42.05% (37 of 88) (P < 0.05; OR = 2.41, 95% CI: 1.26–4.64). Helicobacter pylori prevalence increased with age from 37.50% (12 of 32) for children aged <3 years, 50.00% (53 of 106) aged 3–6 years and 71.05% (27 of 38) aged 7–10 years (P > 0.05; OR = 0.81, 95% CI: 0.34–1.91). The frequency of infection was significantly higher in males, 64.00% (55 of 86) than in females, 41.11% (37 of 90), (P < 0.05; OR = 2.67, 95% CI: 1.39–5.17).

Conclusions  This study highlights the continuing importance of age, sex and socioeconomic status in the acquisition of H. pylori infection.
Environmental control of schistosomiasis through community participation in a Moroccan oasis
Authors: Boelee Eline , Laamrani Hammou
Published: October 2004

Akka oasis, in the province of Tata, southern Morocco, is one of the oldest foci of urinary schistosomiasis in Morocco where transmission is still taking place. We report the results of two studies: a cross‐sectional snail survey investigated the distribution of Bulinus truncatus in relation to habitat factors in the Akka traditional irrigation system. The presence of aquatic vegetation, especially Potamogeton sp. was identified as a key factor determining snail occurrence and abundance in canals, impoundments and isolated small puddles and streamlets in the Akka riverbed. In a participatory rapid appraisal, the community identified snail control as a way to reduce transmission of schistosomiasis. Without any further outside incentives, the local irrigation committee implemented repeated cleaning and vegetation removal in canals. A longitudinal study evaluated the effect of these measures on populations of B. truncatus. Snail and egg mass densities showed significant reductions after repeated vegetation clearing in the study sites. The participatory approach led to low‐cost, environment‐friendly schistosomiasis control measures that were effective and sustainable.
Circulating concentrations of cardiac proteins in complicated and uncomplicated Plasmodium falciparum malaria
Authors: Ehrhardt S. , Wichmann D. , Hemmer C. J. , Burchard G. D. , Brattig N. W.
Published: October 2004

In an unmatched case–control study of 63 non‐immune European patients with uncomplicated (n = 52) and complicated (n = 11) falciparum malaria, serum levels of N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), heart‐type fatty acid‐binding protein (H‐FABP), myoglobin, troponin T and creatin kinase‐muscle brain were compared. Elevated levels of NT‐proBNP and H‐FABP indicated myocardial impairment in complicated but not in uncomplicated falciparum malaria. The clinical impact of these findings remains to be evaluated. The pathophysiology of cardiac impairment in complicated falciparum malaria warrants further investigation.
Antibodies directed against nitrosylated neoepitopes in sera of patients with human African trypanosomiasis
Authors: Semballa S. , Geffard M. , Daulouede S. , Malvy D. , Veyret B. , Lemesre J.‐L. , Holzmuller P. , Mnaimneh S. , Vincendeau P.
Published: October 2004

Antibodies directed against nitrosylated epitopes have been found in sera from patients suffering from human African trypanosomiasis (HAT) but not in sera from control subjects living in the same endemic area or African control subjects living in France. We conjugated amino acids to albumin by glutaraldehyde (conjugates) and then nitrosylated the conjugates. Both conjugates and nitrosylated conjugates were analysed by enzyme‐linked immunosorbent assay (ELISA). We detected antibodies directed against nitrosylated l‐cysteine and l‐tyrosine conjugates; antibody levels were higher in stage II patients than in stage I. Patients with severe clinical signs had higher antibody levels, and antibody levels were highest in patients with major neurological signs. Antibody response was only associated with the IgM isotype. We evaluated antibody specificity and avidity by competition experiments using conjugates and nitrosylated conjugates. Avidity was around 2 ×10−6 m for the S‐nitroso‐cysteine epitope and 2 × 10−8 m for the S‐nitroso‐tyrosine epitope. Detection of circulating antibodies to S‐nitroso‐cysteine and S‐nitroso‐tyrosine epitopes provides indirect evidence for nitric oxide (NO) involvement in HAT and their levels are correlated with disease severity.
Diarrhoea, vomiting and the role of milk consumption: perceived and identified risk in Bamako (Mali)
Authors: Hetzel Manuel , Bonfoh Bassirou , Farah Zakaria , Traoré Malick , Simbé Cheick F. , Alfaroukh Idriss O. , Schelling Esther , Tanner Marcel , Zinsstag Jakob
Published: October 2004

Objectives  To evaluate the public health impact of milk contamination in Bamako, Mali.

Methods  A case–control study assessed the risk‐factors for food‐borne toxi‐infections with diarrhoea and vomiting as main clinical picture. A total of 131 schoolchildren between 5 and 20 years of age were interviewed by trained interviewers in schools in Bamako. A structured questionnaire was used to record health problems, food and particularly milk consumption habits and socio‐economic indicators.

Results  Final multivariate logistic regression analysis identified regular consumption of boiled milk [odds ratio(OR) = 4.38; 95% CI = 1.15–16.71], age between 5 and 10 years (OR vs. age group 11–15 years = 3.28; 95% CI = 1.09–9.85) and the existence of dry latrines in the household (OR = 7.65; 95% CI = 1.92–30.55) as risk factors for diarrhoea and vomiting. Other milk products and the socio‐economic level of the household were not significantly associated with the outcome. Many people were unaware of the potential risks of milk consumption.

Conclusions  Milk products may be a risk factor for food‐borne toxi‐infections. Attention has to be paid to products considered ‘safe’, such as boiled or pasteurized milk. The low awareness of potential risks of many people may increase the risk of milk consumption. To achieve a sustainable increase in local milk production in Africa, milk quantity and production and transformation quality should be improved simultaneously.
Evaluation of the direct agglutination test based on freeze‐dried Leishmania donovani promastigotes for the serodiagnosis of visceral leishmaniasis in Sudanese patients
Authors: Abdallah Khalid A. A. , Nour Bakri Y. M. , Schallig Henk D. F. H. , Mergani Adil , Hamid Zohal , Elkarim Abdallah Abd , Saeed Osman K. , Mohamadani Ahmed A.
Published: October 2004

The direct agglutination test (DAT) based on freeze‐dried (FD) Leishmania donovani antigen was evaluated for the serodiagnosis of kala‐azar in a rural setting in eastern Sudan. The performance of the FD‐DAT was compared with standard liquid antigen (LQ) by testing serum samples and blood samples collected on filter paper of microscopically and PCR‐confirmed VL patients, apparently healthy endemic controls and patients with other relevant infectious diseases for the region. In the present study, the FD‐DAT had a sensitivity of 96.8% and a specificity of 96.2%. The LQ‐DAT had a sensitivity of 91.0% and a specificity of 96.6%. A high degree of agreement (97.3%; r‐value 0.94) was observed between the FD‐DAT and the LQ‐DAT, as well as between the FD‐DAT performed on serum samples and corresponding blood samples collected on filter paper (agreement 97.8%; r‐value 0.79). The FD‐DAT is very suitable as diagnostic test for kala‐azar in remote rural conditions as it is sensitive, specific and stable. The antigen is affordable, reproducible and available, which contributes to the sustainability of the DAT as a diagnostic test for VL.
Mosquito nets and the poor: can social marketing redress inequities in access?
Authors: Nathan Rose , Masanja Honorati , Mshinda Hassan , Schellenberg Joanna A. , de Savigny Don , Lengeler Christian , Tanner Marcel , Victora Cesar G.
Published: October 2004

Treated mosquito nets are a practical malaria control tool. However, implementation of efficient delivery mechanisms remains a challenge. We investigated whether social marketing of treated mosquito nets results in decreased equity in rural Tanzania, through household surveys before the start of a social marketing programme and 3 years later. About 12 000 household heads were asked about ownership of nets and other assets including a tin roof, radio, or bicycle. A socio‐economic status score was developed for each household. Net ownership was calculated for households in each quintile of this score, from poorest to least poor. In 1997, about 20% of the poorest households and over 60% of the least poor households owned a mosquito net. Three years later, more than half of the poorest households owned a net, as did over 90% of the least poor: the ratio of net ownership among the poorest to least poor increased from 0.3 in 1997 to 0.6 in 2000. Social marketing in the presence of an active private sector for nets was associated with increased equity.
Assessment of disease and infection of lymphatic filariasis in Northeastern Cambodia
Authors: Leang Rithea , Socheat Duong , Bin Boravong , Bunkea Tol , Odermatt Peter
Published: October 2004

We assessed the filariasis disease burden in four northeastern provinces of Cambodia by using and validating a key‐informant questionnaire, consisting of four questions, with pictures of patients with leg elephantiasis and hydrocoele. The questionnaire was distributed and collected through the school, health and administrative systems. Validation surveys included clinical examination, a card test for W. bancrofti (ICT Filariasis card test, AMRADTM) and night blood finger prick examination of patients reported with clinical elephantiasis. Only 48.0% of questionnaires were returned. A total of 220 patients were reported, mostly from Stung Treng (36.8%) and Rattanakiri provinces (35.0%). Key‐informants reported patients with lymphatic filariasis with a sensitivity of 85.7% for leg and 97.0% for scrotum morbidity, and with a specificity of 95.6%. However, substantial over‐reporting resulted in very low positive predictive values for elephantiasis of 19.4% for legs and of 23.7% for the scrotum. As 97.4% of patients with clinical lymphatic filariasis were older than 40 years, the diagnostic performance of the questionnaire would be improved by restricting its use to that age group. About 0.7% of 3490 W. bancrofti card tests were positive; the prevalence was 1.94% (12/618) in Rattanakiri, 0.38% (4/1055) in Stung Treng and 0.22% (2/919) in Preah Vihear. W. bancrofti microfilaria were identified in blood from two patients in Rattanakiri (0.32%) and from one patient in Stung Treng (0.09%). Brugia malayi microfilaria were identified in blood from five patients in Rattanakiri (0.81%) only. No patients with microfilariaemia were identified in Preah Vehear. In Mondulkiri province all investigations (card test, night blood examination, clinical examination) for lymphatic filariasis were negative. Our findings confirm the usefulness of key‐informant questionnaire for the identification of filariasis patients provided that high adherence can be achieved. Lymphatic filariasis infection and disease is present in northern Cambodian provinces but the burdens of disease and infection are relatively low. These results are being used in the implementation of the national control programme for lymphatic filariasis.
iNOS promoter variants and severe malaria in Ghanaian children
Authors: Cramer Jakob P. , Mockenhaupt Frank P. , Ehrhardt Stephan , Burkhardt Jana , Otchwemah Rowland N. , Dietz Ekkehardt , Gellert Sabine , Bienzle Ulrich
Published: October 2004

Nitric oxide is an important mediator in the host defence against Plasmodium falciparum malaria. It has antiparasitic effects in vitro. However, its role in clinical disease remains controversial. Polymorphisms in the inducible nitric oxide synthase promoter (iNOS; −954G→C, −1173C→T, −2.6 kb CCTTT(n) microsatellite) may influence susceptibility to and severity of malaria. We tested this hypothesis in a case–control study among Ghanaian children with severe malaria (SM) and asymptomatic parasitaemia, respectively, and in healthy controls. In this study, the respective frequencies of iNOS−954G→C and −1173C→T did not differ between groups but ≥13 microsatellite copies were associated with SM. −954G→C and −1173C→T were in linkage disequilibrium with CCTTT(8) and CCTTT(13), respectively. −954G→C/CCTTT(8) protected against hyperparasitaemia whereas −1173C→T/CCTTT(13) increased fatality. These findings suggest that iNOS promoter haplotypes rather than single nucleotide polymorphisms are associated with malaria in Ghanaian children.
Is amodiaquine failing in Rwanda? Efficacy of amodiaquine alone and combined with artesunate in children with uncomplicated malaria
Authors: Rwagacondo Claude E. , Karema Corine , Mugisha Veronique , Erhart Annette , Dujardin Jean‐Claude , Overmeir Chantal Van , Ringwald Pascal , D'Alessandro Umberto
Published: October 2004

We investigated the safety and efficacy of amodiaquine alone (AQ) and combined with artesunate (AQ + AS) in 308 Rwandan children 6–59 months old with uncomplicated Plasmodium falciparum malaria attending three sentinel sites. The two treatment regimes were well tolerated and no serious adverse events were recorded. After excluding new infections, children treated with AQ + AS had fewer clinical failures at day 28 after treatment than those treated with AQ alone: OR = 0.20 [95% CI: 0.06–0.57 (P = 0.001)]. Total (parasitological and clinical) failure was also significantly less frequent in the AQ + AS group: OR = 0.34 [95% CI: 0.17–0.67 (P = 0.001)]. When adjusting for study site, the hazard ratio for treatment failure was 0.37 [95% CI: 0.20–0.68 (P = 0.001)]. Combining AQ with AS increases the efficacy of the treatment but the apparent increase of AQ resistance observed in just a 1‐year period is worrying and casts doubts on the suitability of implementing AQ + AS as first‐line treatment in Rwanda. Alternative treatments should be identified and tested.
Astroturf: Interest Group Lobbying and Corporate Strategy
Authors: Lyon Thomas P. , Maxwell John W.
Published: October 2004

We study three corporate nonmarket strategies designed to influence the lobbying behavior of other special interest groups: (1) astroturf, in which the firm covertly subsidizes a group with similar views to lobby when it normally would not; (2) the bear hug, in which the firm overtly pays a group to alter its lobbying activities; and (3) self‐regulation, in which the firm voluntarily limits the potential social harm from its activities. All three strategies reduce the informativeness of lobbying, and all reduce the payoff of the public decision‐maker. We show that the decision‐maker would benefit by requiring the public disclosure of funds spent on astroturf lobbying but that the availability of alternative influence strategies limits the impact of such a policy.
Retail Contracting and Organizational Form: Alternatives to Chain Affiliation in the Motel Industry
Authors: Mazzeo Michael J.
Published: October 2004

Most of the existing empirical literature on franchising investigates the share of company‐owned versus franchised establishments within large retail firms. This literature typically has not considered the decision of a business owner to operate an independent business or to become a franchisee. This paper empirically analyzes what determines whether independent ownership or affiliation is observed, using data on the affiliation status of 2,293 motel establishments located throughout the United States. Heterogeneity in the underlying economic environment helps explain affiliation choices at the establishment level. The results also suggest that failure to consider independent establishments may explain the puzzling negative correlation between risk and vertical integration commonly found in the empirical franchising literature.
Agency Problems and Commitment in Delegated Bargaining
Authors: Cai Hongbin , Cont Walter
Published: October 2004

In the context of (one‐sided) delegated bargaining, we analyze how a principal (a seller) should design the delegation contract in order to provide proper incentives for her delegate (an intermediary) and gain strategic advantage against a third party (a buyer). We consider situations in which there are both moral hazard and adverse selection problems in the delegation relationship and where the seller tries to gain strategic advantage by imposing a minimum price above which she pays the delegate a commission. It is shown that incentives and commitment are substitutes. A low‐type agent is given less discretion in dealing with the buyer and weaker incentives, while a high‐type agent is given more discretion and stronger incentives.
Optimal Debt Contracts with Renegotiation
Authors: Usman Murat
Published: October 2004

This paper sutudies the role of debt in committing a seller not to trade at a low price. We consider a discrete‐time finite‐horizon buyer–seller relationship. The seller makes an upfront relationship‐specific investment, which is financed with debt. Debt then is repaid gradually to mitigate the hold‐up risk. Even though debt is renegotiable, under the assumption that with a small probability renegotiation may fail and may lead to inefficient liquidation, debt still can be used as a commitment device. We solve for renegotiation proof dynamic debt contracts that are optimal for the seller and show that debt is repaid over the entire course of the relationship with declining repayments.
Asymmetry and Mating Success in a Periodical Cicada,Magicicada septendecim(Hemiptera: Cicadidae)
Authors: Cooley John R.
Published: October 2004

Phenotypic symmetry results from both a genetic predisposition and the influence of the developmental environment. Although most studies of mate choice and phenotypic asymmetry are couched in terms of active choice for ‘good genes’, an alternative viewpoint is to consider incidental mating biases that arise from the functional effects of asymmetrical phenotypes. This paper (i) discusses the specific situations in which symmetry‐based mate choice may be likely, and (ii) presents research on female mate choice and symmetry in the periodical cicada,Magicicada septendecim(L.). Male mating aggregations and lack of mating gifts or parental care make this species an ideal target for studying female choice for superior mates, and thus for a relationship between male symmetry and male mating success.
Competing Females and Caring Males. Polyandry and Sex‐Role Reversal in African Black Coucals,Centropus grillii
Authors: Goymann Wolfgang , Wittenzellner Andrea , Wingfield John C.
Published: October 2004

Most species of birds show bi‐parental or female‐only care. However, a minority of species is polyandrous and expresses male‐only care. So far, such reversals in sex roles have been demonstrated only in precocial bird species, but there was suggestive evidence that such a mating system may occur in one altricial bird species, the black coucal,Centropus grillii. In a field study in Tanzania we investigated whether black coucals are sex‐role reversed and polyandrous. We found that males were mated to one female, rarely vocalized and provided all parental care from incubation of eggs to feeding of young. In contrast, female black coucals were about 69% heavier and 39% larger than males and polyandrous. They spent a large proportion of time calling from conspicuous perches, defended breeding territories, did not help in provisioning young and had a higher potential reproductive rate than males. We conclude that the black coucal currently represents the only altricial bird species with sole male parental care and a classical polyandrous mating system. High nest predation pressure and small territory sizes due to high food abundance may have been important factors in the evolution of sex‐role reversal and polyandry in this species.
Clustering Objects on Subsets of Attributes (with Discussion)
Authors: Friedman Jerome H. , Meulman Jacqueline J.
Published: October 2004

A new procedure is proposed for clustering attribute value data. When used in conjunction with conventional distance-based clustering algorithms this procedure encourages those algorithms to detect automatically subgroups of objects that preferentially cluster on subsets of the attribute variables rather than on all of them simultaneously. The relevant attribute subsets for each individual cluster can be different and partially (or completely) overlap with those of other clusters. Enhancements for increasing sensitivity for detecting especially low cardinality groups clustering on a small subset of variables are discussed. Applications in different domains, including gene expression arrays, are presented.
Restricted Likelihood Ratio Lack-of-Fit Tests Using Mixed Spline Models
Authors: Claeskens Gerda
Published: October 2004

Penalized regression spline models afford a simple mixed model representation in which variance components control the degree of non-linearity in the smooth function estimates. This motivates the study of lack-of-fit tests based on the restricted maximum likelihood ratio statistic which tests whether variance components are 0 against the alternative of taking on positive values. For this one-sided testing problem a further complication is that the variance component belongs to the boundary of the parameter space under the null hypothesis. Conditions are obtained on the design of the regression spline models under which asymptotic distribution theory applies, and finite sample approximations to the asymptotic distribution are provided. Test statistics are studied for simple as well as multiple-regression models.
Merging Information for Semiparametric Density Estimation
Authors: Fokianos Konstantinos
Published: October 2004

The density ratio model specifies that the likelihood ratio of m−1 probability density functions with respect to the mth is of known parametric form without reference to any parametric model. We study the semiparametric inference problem that is related to the density ratio model by appealing to the methodology of empirical likelihood. The combined data from all the samples leads to more efficient kernel density estimators for the unknown distributions. We adopt variants of well-established techniques to choose the smoothing parameter for the density estimators proposed.
Estimation of Generalized Linear Latent Variable Models
Authors: Huber Philippe , Ronchetti Elvezio , Victoria-Feser Maria-Pia
Published: October 2004

Generalized linear latent variable models (GLLVMs), as defined by Bartholomew and Knott, enable modelling of relationships between manifest and latent variables. They extend structural equation modelling techniques, which are powerful tools in the social sciences. However, because of the complexity of the log-likelihood function of a GLLVM, an approximation such as numerical integration must be used for inference. This can limit drastically the number of variables in the model and can lead to biased estimators. We propose a new estimator for the parameters of a GLLVM, based on a Laplace approximation to the likelihood function and which can be computed even for models with a large number of variables. The new estimator can be viewed as an M-estimator, leading to readily available asymptotic properties and correct inference. A simulation study shows its excellent finite sample properties, in particular when compared with a well-established approach such as LISREL. A real data example on the measurement of wealth for the computation of multidimensional inequality is analysed to highlight the importance of the methodology.
Efficiency of Generalized Estimating Equations for Binary Responses
Authors: Rao Chaganty N. , Joe Harry
Published: October 2004

Using standard correlation bounds, we show that in generalized estimation equations (GEEs) the so-called ‘working correlation matrix’R(α) for analysing binary data cannot in general be the true correlation matrix of the data. Methods for estimating the correlation param-eter in current GEE software for binary responses disregard these bounds. To show that the GEE applied on binary data has high efficiency, we use a multivariate binary model so that the covariance matrix from estimating equation theory can be compared with the inverse Fisher information matrix. But R(α) should be viewed as the weight matrix, and it should not be confused with the correlation matrix of the binary responses. We also do a comparison with more general weighted estimating equations by using a matrix Cauchy–Schwarz inequality. Our analysis leads to simple rules for the choice of α in an exchangeable or autoregressive AR(1) weight matrix R(α), based on the strength of dependence between the binary variables. An example is given to illustrate the assessment of dependence and choice of α.
Approximating Hidden Gaussian Markov Random Fields
Authors: Rue Håvard , Steinsland Ingelin , Erland Sveinung
Published: October 2004

Gaussian Markov random-field (GMRF) models are frequently used in a wide variety of applications. In most cases parts of the GMRF are observed through mutually independent data; hence the full conditional of the GMRF, a hidden GMRF (HGMRF), is of interest. We are concerned with the case where the likelihood is non-Gaussian, leading to non-Gaussian HGMRF models. Several researchers have constructed block sampling Markov chain Monte Carlo schemes based on approximations of the HGMRF by a GMRF, using a second-order expansion of the log-density at or near the mode. This is possible as the GMRF approximation can be sampled exactly with a known normalizing constant. The Markov property of the GMRF approximation yields computational efficiency.The main contribution in the paper is to go beyond the GMRF approximation and to construct a class of non-Gaussian approximations which adapt automatically to the particular HGMRF that is under study. The accuracy can be tuned by intuitive parameters to nearly any precision. These non-Gaussian approximations share the same computational complexity as those which are based on GMRFs and can be sampled exactly with computable normalizing constants. We apply our approximations in spatial disease mapping and model-based geostatistical models with different likelihoods, obtain procedures for block updating and construct Metropolized independence samplers.
Real Nonparametric Regression Using Complex Wavelets
Authors: Barber Stuart , Nason Guy P.
Published: October 2004

Wavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients.
Nonparametric Inference About Service Time Distribution from Indirect Measurements
Authors: Hall Peter , Park Juhyun
Published: October 2004

In studies of properties of queues, for example in relation to Internet traffic, a subject that is of particular interest is the ‘shape’ of service time distribution. For example, we might wish to know whether the service time density is unimodal, suggesting that service time distribution is possibly homogeneous, or whether it is multimodal, indicating that there are two or more distinct customer populations. However, even in relatively controlled experiments we may not have access to explicit service time data. Our only information might be the durations of service time clusters, i.e. of busy periods. We wish to ‘deconvolve’ these concatenations, and to construct empirical approximations to the distribution and, particularly, the density function of service time. Explicit solutions of these problems will be suggested. In particular, a kernel-based ‘deconvolution’ estimator of service time density will be introduced, admitting conventional approaches to the choice of bandwidth.
Benefits of Treating Highly Disabled Migraine Patients with Zolmitriptan while Pain is Mild
Authors: Klapper J , Lucas C , Røsjø Ø , Charlesworth B ,   on behalf of the ZODIAC study group
Published: October 2004

Clinical trials of migraine therapy often require treatment when migraine pain intensity is moderate or severe, but many physicians find this practice artificial and patients often prefer to treat while pain is mild. This randomized, placebo-controlled study assessed the efficacy of zolmitriptan 2.5 mg in treating migraine while pain is mild, in patients who typically experience migraine attacks that are initially mild, but progress to moderate or severe. The intent-to-treat population comprised 280 patients (138 zolmitriptan; 148 placebo), with mean MIDAS grades of 29.6 (zolmitriptan) and 27.6 (placebo). Zolmitriptan 2.5 mg provided a significantly higher pain-free rate at 2 h (43.4% vs. 18.4% placebo; P <0.0001). Significantly fewer zolmitriptan patients reported progression of headache pain to moderate or severe intensity 2 h postdose (53.7% vs. 70.4% placebo; P < 0.01), or required further medication within 24 h (46.4% vs. 71.1% placebo; P <0.0001). The efficacy of zolmitriptan was more pronounced in patients treating during the first 15 min following pain onset. Adverse events were reported in 31.2% of patients treated with zolmitriptan (vs. 11.3% for placebo), and the incidence was lower in patients who treated early after attack onset. Zolmitriptan provides high efficacy when treating migraine while pain is mild, with the clinical benefits being more pronounced when treating early after migraine onset.
Clinical Features, Effectiveness Of Drug-Based Treatment, and Prognosis of New Daily Persistent Headache (NDPH): 30 Cases in Japan
Authors: Takase Y , Nakano M , Tatsumi C , Matsuyama T
Published: October 2004

Although new daily persistent headache (NDPH) is considered to be one of the most refractory headaches to pharmacological treatment, the effectiveness of drug-based treatment, and the prognosis of NDPH have not been well studied. The purpose of this study is to evaluate the effectiveness of pharmacological treatment of NDPH. Seventeen men and 13 women who met the IHS diagnostic criteria for NDPH, were treated for five years from November 1997 to October 2002, and whose headache conditions were entirely available for reference as of October 2003 were investigated in Toyonaka Municipal Hospital. Mean age at onset 35.0 years (range 13-73 years). The onset of headache occurred in relation to a stressful life event in six (20%) patients and any precipitating events could not be identified in 24 (80%) patients. For treatment, muscle relaxants were first administered and if no effect was observed, tricyclic antidepressants, selective serotonin reuptake inhibitors, and antiepleptic drugs were subsequently administered. Results of the drug-based treatments in the 30 cases were ‘very effective’ for eight (27%) cases, ‘moderately effective’ for one (3%) case, ‘mildly effective’ for six (20%) cases, and ‘not effective’ for 15 (50%) cases. According to the survey on the phone for the patients who did not improve to the level of ‘mildly effective’ or better and did not come back to our institution as of October 2003, there were no cases found to have spontaneously improved to the level of ‘mildly effective’ or better. These results suggest that NDPH is highly recalcitrant to the treatments with poor prognosis and better treatments are needed.
Prevalence of Migraine in a Rural Area in South Tanzania: A door-to-door Survey
Authors: Dent W , Spiss HK , Helbok R , Matuja WBP , Scheunemann S , Schmutzhard E
Published: October 2004

We set out to assess the prevalence during the previous year of migraine in a rural area surrounding the Mnero Diocesan Hospital in Southern-Tanzania. A door-to-door survey from August until December 1999 using a questionnaire based on the criteria of the International Headache Society (IHS), including 1047 households with 3351 persons, was done, consisting of a screening dialogue with a representative family member followed by a face-to-face interview with the affected subject. Of the 3351 participants (female 1876; male 1475; age > 10 years), 23.1% had suffered from headache during the past year; overall prevalence of migraine was 5.0% (female 7.0%; male 2.6%); 1.4% reported migraine without aura (female 1.8%; male 0.9%); and 3.6% reported migraine with aura (female 5.2%, male 1.6%). The peak prevalence was found in female persons in the fourth (11.1%), in male persons in the third decade of life (3.8%). Compared with other African surveys, the prevalence rate of migraine headache in South Tanzania is slightly higher than among Ethiopian and Zimbabwean Africans.
Glyceryl Trinitrate may Trigger Endogenous Nitric Oxide Production in Patients with Chronic Tension-Type Headache
Authors: Ashina M , Simonsen H , Bendtsen L , Jensen R , Olesen J
Published: October 2004

Experimental studies in humans have shown that nitric oxide (NO) may play an important role in initiation of primary headaches. It has been proposed that activation of L-arginine-NO pathway and increased endogenous production of NO may be responsible for NO induced headache. NO is synthesized from L-arginine and that reaction also yields citrulline. In the present study we aimed to investigate plasma levels of citrulline and arginine as markers of NO production after infusion of the NO donor, glyceryl trinitrate (GTN). We recruited 16 patients with chronic tension-type headache and 16 healthy controls. The subjects were randomly allocated to receive 0.5 μg/kg/min GTN or placebo over 20 min. Patients were examined on headache free days. Blood samples were collected at baseline and 60 min after start of infusion. Both patients and controls developed stronger immediate headache on the GTN day than on the placebo day ( P = 0.008). The headache was more pronounced in patients than in controls ( P = 0.02). Plasma levels of citrulline increased significantly 60 min after start of GTN infusion compared to placebo infusion in patients ( P = 0.01) but not in controls ( P = 0.50). Plasma levels of arginine were unchanged in both patients ( P = 0.12) and controls ( P =0.18). We suggest that GTN administration may trigger endogenous production of NO in patients with chronic tension-type headache resulting in activation of perivascular sensory afferents.