Indirect Inference for Time Series Using the Empirical Characteristic Function and Control Variates

We estimate the parameter of a stationary time series process by minimizing the integrated weighted mean squared error between the empirical and simulated characteristic function, when the true characteristic functions cannot be explicitly computed. Motivated by Indirect Inference, we use a Monte Carlo approximation of the characteristic function based on iid simulated blocks. As a classical variance reduction technique, we propose the use of control variates for reducing the variance of this Monte Carlo approximation. These two approximations yield two new estimators that are applicable to a large class of time series processes. We show consistency and asymptotic normality of the parameter estimators under strong mixing, moment conditions, and smoothness of the simulated blocks with respect to its parameter. In a simulation study we show the good performance of these new simulation based estimators, and the superiority of the control variates based estimator for Poisson driven time series of counts.Comment: 38 pages, 2 figure

COVID-19, BUSINESS RESILIENCE, AND GOVERNMENT CONTRACTING: DID THE PAYCHECK PROTECTION PROGRAM (PPP) IMPACT THE DISASTER RESILIENCE OF SMALL DISADVANTAGED BUSINESSES AFTER COVID-19? THE CASE OF GOVERNMENT CONTRACTING IN THE UNITED STATES.

This dissertation examines the disaster resilience of disadvantaged small businesses that have engaged in contracting activities with the U.S. federal government from 2018 to 2023. Federal government agencies procure goods and services from small businesses in the private sector through contracts that allow those businesses to be competitive in the market and overcome the impact of disasters on their activities. The notion of disaster resilience has traditionally focused on natural hazards like wildfires, earthquakes, tornadoes, or hurricanes; however, lately, it has been increasingly applied to diverse contexts. Business resilience to disasters refers to businesses\u27 ability to return to their pre-disaster activities and thrive following a calamity. Starting in early 2020, the COVID-19 virus caused millions of deaths worldwide and unprecedented business disruption for approximately two years. In March 2020, President Trump declared the pandemic resulting from the virus a national disaster. In response, the U.S. Congress enacted the CARES Act, which included the Paycheck Protection Program (PPP) to help American small businesses, primarily those owned by individuals from disadvantaged backgrounds, continue operating during and after this disaster. Millions of businesses, including recipients of federal government contracts, benefited from the program. With a focus on small businesses that were awarded federal government contracts each year from 2018 to 2023 and are owned by members of disadvantaged communities, such as minorities, women, and veterans, this dissertation explores the impact of the PPP loans on the disaster resilience of those businesses. Using publicly available government spending data from USASpending.gov and PPP loan information from the U.S. Small Business Administration (SBA), this dissertation analyzes the post-pandemic contracts awarded to those businesses by the federal government to determine the PPP’s impact on contracts awarded to those businesses post-pandemic. Following the data analysis, I found that, in general, PPP loans positively impacted the disaster resilience of small businesses engaged in federal government contracting. My findings revealed the effectiveness of the PPP as a federal disaster loan program. This dissertation applies the institutional theory on the impact of the PPP, as a policy, on business resilience, and addresses academic recommendations for additional studies on business resilience and federal disaster financial assistance for businesses engaged in public procurement

Global Reparations within Capitalism:Aspirations and Tensions in Contemporary Movements for Reparatory Justice

The idea of global reparations has received increasing attention in recent years, not only with respect to legacies of slavery and colonialism, but also to interrelated issues such as climate change, debt crisis, or ongoing financial transfers from the Global South to the Global North. This article, which introduces and sets the Debate for the 2024 Forum issue on the political economy of 21st century global reparations, offers a critical perspective on contemporary global reparations agendas, including their macroeconomic and development implications for the Global South. It highlights the contentious, unresolved questions about how reparations movements should interact with the highly unequal structures of global capitalism. To what degree should they seek large redistributive gains within these structures, or else aim for more revolutionary standpoints which reject these structures? If the former, would this compromise any hope for reparations to be truly transformative and able to address the challenges presented by global white supremacy? The hope of reparations movements is to make progressive gains that could become the catalyst for more transformative changes on a global scale. At the same time, sympathetic critics question whether reparations are feasible or should be a primary focus of advocacy for achieving racial and climate justice on national as well as global levels. In outlining these points of debate, the article also considers the questions of how to make global reparations work for recipients, and how to finance them. It concludes by elaborating on the challenge of moving towards a more developmentalist emphasis of ‘systemic reparations’.</p

Urine diverting dry toilets as appropriate adaptation to flood prone areas in cities of developing countries

Living in flood prone areas is a serious challenge for citizen in developing countries, especially in Cameroon. MAFADY Project has been working through identifying best low cost sanitation technologies so as to propose a technology suited to flooded areas of Wouri estuary in Douala. From a defined set of social, financial and technical criteria, analysis of existing sanitation technologies developed in flooded ecosystems was made, and it was found that elevated Urine diverting dry toilets were the one suitable for flood pone areas. A plastic Drum twin pit Urine Diverting Dry Toilet (DUDDT) model was designed and constructed. This paper presents: socio-economic and environmental context of the Wouri estuary, the selected criteria and design parameters, the DUDDT, and finally discuss the construction costs. From analysis, this toilet seems to feet flood prone areas, specifically in urban wetlands of developing countries

Isolation and structural elucidation of compounds from Pleiocarpa bicarpellata and their in vitro antiprotozoal activity

Species of the genus Pleiocarpa are used in traditional medicine against fever and malaria. The present study focuses on the isolation and identification of bioactive compounds from P. bicarpellata extracts, and the evaluation of their antiprotozoal activity. Fractionation and isolation combined to LC-HRMS/MS-based dereplication provided 16 compounds: seven indole alkaloids, four indoline alkaloids, two secoiridoid glycosides, two iridoid glycosides, and one phenolic glucoside. One of the quaternary indole alkaloids (7) and one indoline alkaloid (15) have never been reported before. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR experiments, UV, IR, and HRESIMS data. The absolute configurations were determined by comparison of the experimental and calculated ECD data. The extracts and isolated compounds were evaluated for their antiprotozoal activity towards Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum, as well as for their cytotoxicity against rat skeletal myoblast L6 cells. The dichloromethane/methanol (1:1) root extract showed strong activity against P. falciparum (IC50 value of 3.5 microg/mL). Among the compounds isolated, tubotaiwine (13) displayed the most significant antiplasmodial activity with an IC50 value of 8.5 microM and a selectivity index of 23.4. Therefore, P. bicarpallata extract can be considered as a source of indole alkaloids with antiplasmodial activity

Étude ethnobotanique des plantes médicinales commercialisées dans les marchés de la ville de Douala, Cameroun

Objectif: L’objectif de cette étude est d’inventorier et d’identifier les vertus thérapeutiques des plantes médicinales commercialisées dans la ville de Douala (Cameroun).Méthodologie et résultats: Des enquêtes ethnobotaniques ont été conduites de juillet à août 2012, auprès de 54 herboristes dans cinq marchés en utilisant des interviews directes et semi-structurées. L’étude a permis d’identifier 84 espèces réparties en 78 genres et 50 familles dont les plus représentées ont été les Asteraceae (9 espèces), Fabaceae (6 espèces) et Lamiaceae (4 espèces). Les troubles infectieux (66,7 %) et gynécoobstétriques et urologiques ont été majoritairement représentés. La recherche du degré de consensus (ICF) révèle que 3 catégories ont atteint des valeurs élevées : les troubles asthéniques (0,8), dermatologiques (0,6), gynéco-obstétriques et urologiques (0,5).Conclusion et application des résultats: Cette étude montre l’importance des enquêtes ethnobotaniques dans la phytothérapie et les limites des herboristes de la pharmacopée traditionnelle.Mots clés: Ethnobotanique, plantes médicinales commercialisées, maladiesEnglish AbstractObjective: The objective of this study was to make an inventory and to identify therapeutic properties of medicinal plants sold in the city of Douala (Cameroon).Methodology and Results: Ethnobotanical surveys were conducted from July to August 2012 beside 54 herbalists in five markets using direct and semi-structured interviews. The study identified 84 species distributed in 78 genera and 50 families, the most represented were Asteraceae (9 species), Fabaceae (6 species) and Lamiaceae (4 species). Infectious disorders (66.7%) and gyneco-obstetrical and urological disorders were mostly represented. Research on the degree of consensus (ICF) reveals that three categories reached high values: asthenic (0.8), skin (0.6), gyneco-obstetrical and urological (0.5) disorders.Conclusion and applications of results: This study shows the importance of ethnobotanical surveys in herbal medicine and limitations of herbalists of traditional medicine.Keys: Ethnobotany, sold medicinal plants, disease

Facteurs de risque de démence dans une population de personnes âgées sénégalaises

Description La démence est devenue un problème de santé publique. Dans le but d’une prévention, il est important de connaitre son épidémiologie au Sénégal. L’objectif de cette étude était d’identifier les facteurs de risque de démence dans une population de personnes âgées sénégalaises. MéthodesUne étude transversale a été réalisée du 01 Mars 2004 au 31 Décembre 2005 auprès d’une population de 872 personnes âgées de 55ans et plus utilisant le Centre Médicosocial et Universitaire de l’Institut de Prévoyance Retraite du Sénégal pour des soins. Par une étude en deux phases, des données sociodémographiques, sur le mode de vie, le réseau social, les antécédents ont été collectées à l’aide d’un questionnaire structuré complété par un examen clinique et une évaluation neuropsychologique. Le diagnostic de démence reposait sur des critères DSM IV-R

Prévalence de la démence dans une population de personnes âgées sénégalaises

Description Avec le vieillissement de la population, survient la démence dans la population de personnes âgées. Objectif. L’objectif de cette étude était d’estimer la prévalence de cette affection dans une population de personnes âgées sénégalaises. Méthodes Par une étude transversale qui s’est déroulée du 01 mars 2004 au 31 décembre 2005, des personnes âgées de 55 ans et plus venant consulter pour un problème de santé au Centre Médico-Social et Universitaire de l’IPRES (Sénégal) ont été évaluées sur le plan clinique et neuropsychologique. Des données sur les caractéristiques sociodémographiques, les antécédents médico-chirurgicaux et familiaux, le mode de vie, le réseau social ont été collectées à l’aide d’un questionnaire structuré avec des réponses fermées. Résultat La population à l’étude était composée de 872 personnes. Elles avaient un âge moyen de 67,2 ans ± 7,5.Elles étaient de sexe masculin (62,6%), mariées (79%), non instruites (50,7%). Dans les antécédents, l’HTA, le diabète, les affections respiratoires, les affections rhumatismales, la cataracte et les troublesdigestifs étaient les plus fréquents. Le tabagisme et l’alcoolisme était faible alors que la marche constituait la principale activité physique. Les personnes âgées vivaient en famille avec un bon réseau social.Cinquante huit (58) personnes ont présenté une démence (6,6%). La prévalence de la maladie variait de manière significative avec l’âge et l’instruction. Conclusion Ce résultat confirme que la prévalence de la démence varie en fonction de l’âge et de l’instruction de la personne âgée