Difference equations arise in many fields of mathematics, both as discrete analogs of continuous behavior (analysis, numerical approximations) and as independent models for discrete behavior (population dynamics, economics, biology, ecology, etc.). In recent years, many models - especially in mathematical biology - are based on higher order nonlinear difference equations. As a result, there has been much focus on the existence of periodic solutions of certain classes of these equations and the asymptotic behavior of these periodic solutions. In this dissertation, we study the existence and global attractivity of both periodic and quasiperiodic solutions of two different higher order nonlinear difference equations. Both equations arise in biological applications.

No Brasil, o bicudo da cana-de-açúcar, Sphenophorus levis Vaurie (Coleoptera: Curculionidae) tem se tornado nos últimos anos praga importante da cultura, principalmente no estado de São Paulo onde as perdas alcançam 30 ton/ha/ano e no Sul do estado de Minas Gerais. Isto devido à ausência de medidas preventivas para a disseminação e ao crescimento da área plantada, decorrente da alta demanda de álcool. Existem diversos métodos para o seu controle e um dos mais empregados são as iscas tóxicas; apenas impregnadas com o inseticida carbaril não existindo alternativas, o que pode favorecer a aparecimento de populações resistentes do inseto, dificultando o controle. Sendo assim, é evidente a necessidade de investigar outros inseticidas tão ou mais eficientes visando aumentar inclusive a eficiência das iscas utilizadas atualmente através da incorporação de substâncias mais atraentes. O presente trabalho foi realizado no Departamento de Entomologia, Fitopatologia e Zoologia Agrícola da Escola Superior de Agricultura \"Luiz de Queiroz\", Universidade de São Paulo, e teve como objetivos avaliar a atração de adultos de S. levis por meio de olfatômetro \"Y\" a toletes de cana-de-açúcar com e sem melaço a 10% e casca de abacaxi, em diferentes períodos de fermentação (24, 48 e 72hs), horários (diurno e noturno) e sexos (machos e fêmeas) e estabelecer a relação entre os compostos emitidos pelos substratos, acetato de etila e etanol, por meio de cromatografia gasosa, com a atração dos insetos a cada substrato testado; assim como avaliar o efeito letal dos inseticidas cartap e tiametoxam em diferentes dosagens fornecidas através de iscas de cana-de-açúcar no laboratório é validá-los em campo, comparando-os com as capturas das iscas contendo carbaril. Os resultados do laboratório demonstraram que a mistura cana-de-açúcar com melaço fermentado por 24 horas, atraiu os insetos em até 90% e que a resposta dos insetos foi maior no horário diurno, sem diferenças estatísticas entre os sexos. Os inseticidas cartap e tiametoxam nas dosagens 2,0 g p.c/L de água e 0,6 gp.c/L de água respectivamente, ocasionaram níveis de mortalidade superiores a 80% no laboratório. No campo a mortalidade em iscas contendo cartap (2,0 g p.c/L) foi menor que as iscas contendo carbaril e tiametoxam (0,6 g p.c/L) as quais tiveram resultados semelhantes. O maior número de insetos capturados nas iscas tóxicas foi registrado aos 7 dias, nos dias subseqüentes as capturas diminuíram. / In Brazil, the sugarcane weevil, Sphenophorus levis Vaurie (Coleoptera: Curculionidae), has become a serious pest of sugarcane in recent years mainly in the states of São Paulo and south of Minas Gerais where losses caused by this pest surpasses 30 ton/ha/year. This is due to lack of preventive measures for its dissemination and increase in the area planted with sugarcane as a result of high alcohol demand. There are several methods for its control and one of the most utilized methods are toxic baits impregnated with the insecticide carbaryl with no alternatives which could favor the selection of resistant populations of this pest, making control difficult. Therefore, it is necessary to investigate other insecticides including improving the efficiency of baits that are in current use through incorporation of more attractive substances. The present study was realized in the department of Entomology, Plant pathology and Agriculture Zoology of Escola Superior de Agricultura \"Luiz de Queiroz\", University of São Paulo, and had the objective to evaluate the attraction of the adults of S. levis through \"Y\" olfactometer to sugarcane nodes with and without 10% molasses and peelings of pineapple, in different fermentation periods (24, 48 e 72hs), times of the day (diurnal and nocturnal) and sexes (males and females) and to establish the relationship between the compounds emitted by substrates, ethyl acetate and ethanol by use of gas chromatography, with the attraction of insects by each substrate tested, as well as to evaluate the lethal effect of insecticides, cartap and thiametoxan in different doses delivered through sugarcane baits in the laboratory and field validation compared with carbaryl baits. The laboratory results demonstrates that a mixture of sugarcane with molasses fermented for 24 hours, attracted up to 90% of the insects and the insect response was higher during the day without statistical difference between the sexes. The insecticides cartap and thiametoxan at doses 2,0 g p.c/L and 0,6 gp.c/L of water respectively, caused mortality levels higher than 80% in the laboratory. In the field, baits containing cartap (2,0 g p.c/L) captured less insects than those with carbaryl and thiametoxan (0,6 g p.c/L) which had similar results. The highest number of captured insects in toxic baits was registered for 7 days and this diminished in subsequent days.

Les courants de la mondialisation des marchés, marqués par la libre circulation des capitaux et le phénomène du libre-échange ont favorisé la mise en œuvre de politiques communautaires de relance économique et d’attractivité des territoires. C’est dans cette lancée que des regroupements géographiques à visée économique comme la Communauté Économique et Monétaire de l’Afrique Centrale (CEMAC) sont apparus. Six pays de l’Afrique Centrale dont le Cameroun, le Congo, le Gabon, la Guinée Equatoriale, la République Centrafricaine et le Tchad en sont membres et font l’objet de notre analyse sur l’attractivité économique de l’investissement Direct étranger (IDE) dans cette sous-région. L’IDE est devenu un acteur incontournable du processus de développement, et la zone CEMAC une destination privilégiée pour les investisseurs. Il apparait néanmoins une ambiguïté dans les rapports entre le flux d’IDE, la croissance économique et le développement des pays membres de la CEMAC : le taux sans cesse croissant des flux d’IDE entrants dans la sous-région, n’est malheureusement pas toujours synonyme de croissance économique. Pour comprendre ce paradoxe, l’on procède à une analyse des instruments encadrement de l’IDE dans la sous-région CEMAC. Il en ressort que, pour un rendement optimal de ces dispositifs et la garantie d’une croissance économique à long terme dans ces États, il est nécessaire d’associer les politiques actuelles d’attractivité économique des IDE, à une diversification des domaines économiques exploitables , mais aussi adapter les standards internationaux aux spécificités socioculturelles mais aussi économiques de la sous-région CEMAC. / The currents of the globalization of the markets, marked by the free movement of capital and the phenomenon of free trade supported the implementation of Community policies of economic revival and attractivity of the territories. It is in this impetus that geographical regroupings with economic aiming like the Economic community and Monetarist of Central Africa (CEMAC) appeared. Six countries of Central Africa of which Cameroon, Congo, Gabon, Equatorial Guinea, the Central African Republic and Chad are members and are for it, the object our analysis on the economic attractivity of direct foreign investment (FDI) in this under-area. The FDI became an inevitable actor of the development process, and CEMAC zones, a privileged destination for the investors. It appears nevertheless an ambiguity in the relationship between the flow of FDI, the economic growth and the development of the member countries of the CEMAC : the rate unceasingly crescent of flows of FDI entering the under-area, is unfortunately not always synonymous with economic growth. To understand this paradox, one carries out an analysis of the instruments framing of the IDE under-area CEMAC. This reveals that, for an optimal output of these devices and the warranty of one long-term economic growth in these States, it is necessary to associate the current policies of economic attractivity of the FDI, with a diversification of the exploitable economic domains, but also to adapt the international standards to sociocultural but so economic specificities of under-area CEMAC. The case of the countries of the BRICS can in this respect, being used as illustration for an “other way” of thinking the development.

La mondialisation rend plus faciles les échanges entre personnes venant de cultures et d’origines différentes. S’intéressant à la vie des étrangers en Chine, notre étude porte sur la population africaine installée à Yiwu, ville qui accueille la deuxième plus grande communauté africaine en Chine, après Guangzhou. Cette thèse s’interroge sur la source de l’attractivité de Yiwu et sur sa capacité d’intégration. Pour apporter des éléments de réponse, nous avons recueilli entre 2015 et 2016, sous forme de questionnaires et d’entretiens, les témoignages de 81 commerçants étrangers, dont 32 d’origine africaine. L’enquête révèle que la majorité de la population analysée a été attirée par les avantages commerciaux que la ville propose. Le commerce est donc la motivation et le centre d’intérêt de cette communauté, dont les membres, une fois installés, s’efforcent de s’intégrer à la vie commerciale. Néanmoins, leur effort se limite pour l’essentiel à la vie professionnelle. D’une part, le gouvernement local de Yiwu n’est pas totalement ouvert à la population étrangère. Il existe de nombreuses restrictions, qui font obstacle à une intégration complète. D’autre part, les grandes différences culturelles et religieuses forment une barrière spontanée et profonde, presque impossible à dépasser. Ainsi, les commerçants africains fréquentent bien plus leurs compatriotes que leurs partenaires commerciaux chinois. Ils restent principalement au sein de leur communauté dans la vie quotidienne et sociale. Même s’il leur arrive de fréquenter des Chinois en dehors du commerce, cette fréquentation est souvent utilitariste et peu affective. La vraie intégration est donc un état idéal qui demande encore beaucoup d’investissement, si elle est réellement possible. / Globalization makes immigration a lot easier and more efficient among people coming from different backgrounds and cultures. Interested in the lives of foreigners in China, we turned our attention to the African community in Yiwu. Why do these people come to Yiwu and more importantly, how do they adapt themselves to a society which is very different from their own? This thesis tries to find the origins of the city’s attractiveness and if it is immigrant-friendly. Numerous field trips have been made between 2015 and 2016, 81 international businessmen have been interviewed, 32 coming from Africa, with interviews as well as questionnaires. This population is mainly attracted by the commercial advantages of the city. These people are strongly focused on commercial activities, which is their most important immigration motivation. Once settled, they actively try to integrate into local society, as well as to devote themselves successfully to their commercial activities. However, these efforts are strictly limited in their professional life. On the one hand, the governments, both local and central, are not fully welcoming to foreign residents. Multiple administrative restrictions have been observed which prevent them from a better adaptation. On the other hand, important cultural and religious differences between the Africans and the local population create a spontaneous barrier which is practically impossible to exceed. Because of that, African businessmen tend to associate more with people from the same region and avoid the locals when seeking for a deeper connection. They usually stay within their own community in daily and social life. Even if outside-of-work exchanges exist, they are generally a way to enhance the business and therefore not efficient enough in terms of understanding and communication. In other words, real integration is rather an ideal state which still needs a lot of devotions, if it is possible at all.

Cette thèse étudie l’attractivité des territoires et le rôle de la localisation des IDE sur l’économie tunisienne. Il s’agit d’examiner les facteurs d’attractivité de la Tunisie aux IDE et les effets de ces derniers sur l’économie tunisienne. Dans une première analyse empirique, une enquête administrée à un échantillon d’entreprises étrangères ou ayant une participation étrangère a été mise en œuvre dans le but d’identifier les déterminants des IDE. L’utilisation du modèle économétrique de type « logit » nous a permis d’estimer d’une part la probabilité que la Tunisie soit un pays attractif avant la révolution et d’autre part la probabilité que l’entreprise étrangère implante une autre filiale en Tunisie après la révolution. Afin de confirmer l’analyse empirique sur l’identification des facteurs d’attractivité déterminants des IDE, nous avons mis en œuvre, dans une deuxième analyse empirique une autre méthode économétrique à travers un modèle de gravité. Dans une dernière analyse empirique, nous avons étudié les effets des IDE sur l’économie tunisienne en utilisant un modèle à système d’équations simultanées tenant compte des effets spillovers des IDE. / This thesis studies territories attractivity and the role of direct foreign investment localization on the Tunisian economy. It is about examining the factors of attractivity of Tunisia on direct foreign investment and their effects on the Tunisian economy. On a first empirical analysis, an administrative enquiry to a sample of foreign, or having foreign participation enterprises, has been implemented to identify the direct foreign investment determinations. The use of an econometric example of « logit » type allowed us to estimate on one part the probability that Tunisia is an attractive country before the revolution and on the other one that the foreign enterprise implants on other filial in Tunisia after the revolution. To confirm our empirical analysis on the identification of the factors of attractivity determining the direct foreign investment, we implemented, on a second empirical analysis, an other econometric method through a gravity example. On a last empirical analysis, we studied the DFI effects on the Tunisian economy by using a simultaneous equations system example taking into account the DFI spillovers effects.

No Brasil, o bicudo da cana-de-açúcar, Sphenophorus levis Vaurie (Coleoptera: Curculionidae) tem se tornado nos últimos anos praga importante da cultura, principalmente no estado de São Paulo onde as perdas alcançam 30 ton/ha/ano e no Sul do estado de Minas Gerais. Isto devido à ausência de medidas preventivas para a disseminação e ao crescimento da área plantada, decorrente da alta demanda de álcool. Existem diversos métodos para o seu controle e um dos mais empregados são as iscas tóxicas; apenas impregnadas com o inseticida carbaril não existindo alternativas, o que pode favorecer a aparecimento de populações resistentes do inseto, dificultando o controle. Sendo assim, é evidente a necessidade de investigar outros inseticidas tão ou mais eficientes visando aumentar inclusive a eficiência das iscas utilizadas atualmente através da incorporação de substâncias mais atraentes. O presente trabalho foi realizado no Departamento de Entomologia, Fitopatologia e Zoologia Agrícola da Escola Superior de Agricultura \"Luiz de Queiroz\", Universidade de São Paulo, e teve como objetivos avaliar a atração de adultos de S. levis por meio de olfatômetro \"Y\" a toletes de cana-de-açúcar com e sem melaço a 10% e casca de abacaxi, em diferentes períodos de fermentação (24, 48 e 72hs), horários (diurno e noturno) e sexos (machos e fêmeas) e estabelecer a relação entre os compostos emitidos pelos substratos, acetato de etila e etanol, por meio de cromatografia gasosa, com a atração dos insetos a cada substrato testado; assim como avaliar o efeito letal dos inseticidas cartap e tiametoxam em diferentes dosagens fornecidas através de iscas de cana-de-açúcar no laboratório é validá-los em campo, comparando-os com as capturas das iscas contendo carbaril. Os resultados do laboratório demonstraram que a mistura cana-de-açúcar com melaço fermentado por 24 horas, atraiu os insetos em até 90% e que a resposta dos insetos foi maior no horário diurno, sem diferenças estatísticas entre os sexos. Os inseticidas cartap e tiametoxam nas dosagens 2,0 g p.c/L de água e 0,6 gp.c/L de água respectivamente, ocasionaram níveis de mortalidade superiores a 80% no laboratório. No campo a mortalidade em iscas contendo cartap (2,0 g p.c/L) foi menor que as iscas contendo carbaril e tiametoxam (0,6 g p.c/L) as quais tiveram resultados semelhantes. O maior número de insetos capturados nas iscas tóxicas foi registrado aos 7 dias, nos dias subseqüentes as capturas diminuíram. / In Brazil, the sugarcane weevil, Sphenophorus levis Vaurie (Coleoptera: Curculionidae), has become a serious pest of sugarcane in recent years mainly in the states of São Paulo and south of Minas Gerais where losses caused by this pest surpasses 30 ton/ha/year. This is due to lack of preventive measures for its dissemination and increase in the area planted with sugarcane as a result of high alcohol demand. There are several methods for its control and one of the most utilized methods are toxic baits impregnated with the insecticide carbaryl with no alternatives which could favor the selection of resistant populations of this pest, making control difficult. Therefore, it is necessary to investigate other insecticides including improving the efficiency of baits that are in current use through incorporation of more attractive substances. The present study was realized in the department of Entomology, Plant pathology and Agriculture Zoology of Escola Superior de Agricultura \"Luiz de Queiroz\", University of São Paulo, and had the objective to evaluate the attraction of the adults of S. levis through \"Y\" olfactometer to sugarcane nodes with and without 10% molasses and peelings of pineapple, in different fermentation periods (24, 48 e 72hs), times of the day (diurnal and nocturnal) and sexes (males and females) and to establish the relationship between the compounds emitted by substrates, ethyl acetate and ethanol by use of gas chromatography, with the attraction of insects by each substrate tested, as well as to evaluate the lethal effect of insecticides, cartap and thiametoxan in different doses delivered through sugarcane baits in the laboratory and field validation compared with carbaryl baits. The laboratory results demonstrates that a mixture of sugarcane with molasses fermented for 24 hours, attracted up to 90% of the insects and the insect response was higher during the day without statistical difference between the sexes. The insecticides cartap and thiametoxan at doses 2,0 g p.c/L and 0,6 gp.c/L of water respectively, caused mortality levels higher than 80% in the laboratory. In the field, baits containing cartap (2,0 g p.c/L) captured less insects than those with carbaryl and thiametoxan (0,6 g p.c/L) which had similar results. The highest number of captured insects in toxic baits was registered for 7 days and this diminished in subsequent days.

The purpose of this research is to provide an understanding of the relationship that may exist between the institutional determinants and the inward flow of FDI in France. Indeed, the French government and various decisions-makers have attributed the unique growth of the inward flow of FDI to the institutional quality of the country. Moreover, to support this assumption, scholars and experts describe France as an institutionally powerful country. Therefore, in order to test this assumption, we have designed an explanatory analysis of the institutional determinants’ indexes from the WGIs over the period from 2005 to 2018 to test their likely relationship with the FDI inflows in France using descriptive, correlation and regression analyses. This study is based on the rich and furnished literature addressing the role of institutional characteristics in attracting FDI. Although our research has been impacted by the Coronavirus pandemic in terms of data collection and analyses, the corroborating evidences from the empirical findings do not validate the raised hypotheses and bring out many practical implications beneficial for national and local policymakers as well as companies’ managers in the worldwide FDI location competition.

L'Algérie a engagé une politique de libéralisation de son économie et cherche à intégrer l’économie mondiale pour sortir de sa dépendance des hydrocarbures et diversifier son économie. Une politique incitative est mise en place pour accueillir les investissements direct étrangers qui constituent un enjeu majeur pour l’accroissement des échanges, le transfert de technologie, la mise à niveau des sociétés locales et la création d’emploi. D’un autre côté la mise en place d’une économie de marché exige un environnement juridique efficace et stable qui définit clairement les droits et obligations des opérateurs économiques notamment en matière de conclusion de contrats. Le cadre théorique que nous retenons pour répondre à cette question est l’analyse de la place des conventions fiscales dans l’ordre fiscal algérien et sa corrélation avec la politique de promotion des investissements. Les conventions fiscales sont telles réellement au service de l’investissement ? Pour ce faire nous avons mis en exergue tout au long de nos développements l’examen des conventions fiscales à l’épreuve des contrats internationaux permettant d’améliorer la lisibilité et la transparence de la norme fiscale afin de favoriser l’attractivité du territoire / Algeria has initiated a policy of liberalization of its economy and seeks to integrate the world economy to get out of its dependence on hydrocarbons and diversify its economy. An incentive policy is put in place to accommodate foreign direct investment, which is a major challenge for increased trade, technology transfer, upgrading of local companies andjob creation. On the other hand, the establishment of a market economy requires an effective and stable legal environment that clearly defines the rights and obligations of economic operators, particularly with regard to the conclusion of contracts. The theoretical framework that we use to answer this question is the analysis of the place of conventions and taxes in the Algerian tax system and its correlation with the investment promotion policy. Are the tax conventions really such as to serve the investment? To do this, we have highlighted throughout our development the review of tax treaties to the test of international contracts to improve the legibility and transparency of the tax standard to promote the attractiveness of the territory

The aim of the thesis: "Strategic Business Activities of a Chosen Firm" is strategic analysis and the evaluation of present strategic business activities of the chosen firm, which in turn is based on the formulation of recommended strategic business activities, thanks to which the company should hold its market share and in particular the level of income. The goal is the formulation of such measures through which the company will continue to be competitive and be a market leader. The basis of this work is the analysis of internal and external business environment. Partial analyzes are quantitatively evaluated and their results are then incorporated. Based on the results of the strategic analysis is then evaluated the current situation and position in the market and are also formulated various recommendations, including recommended strategies that can be used in the future.

The main source of the human body odour is an axillary region. Human body odour is individually specific and results from genetic and environmental factors. Human body odour is an important sexual attractant for potential partners. It is influenced by environmental factors, such as an emotional state and health. Important environmental factors influencing human body odour are also eating habits. However, we know very little about how particular dietary components shape our body odour. Only the effect of red meat and garlic consumption have been tested. Here we tested the effect of caffeine (from usual source and guarana) and beta- carotene. In our three experiments we used a balanced within-subject experimental design. Volunteers donated twice their body odour: once after ingestion of the tested substance, second time in the control situation. Samples were then assessed for their attractiveness and intensity by group of women. Results showed that caffeine consumption may influence negatively attractiveness and intensity of human body odour. Guarana and beta-carotene did not show any significant results. These results partially confirmed that dietary factors influence the quality of the human body odour. This field should be further studied as a part of the environmental factors influencing human...