Estratégias de acompanhamento para usuários crônicos de benzodiazepínicos atendidos na atenção básica do município de São Francisco do Oeste, Rio Grande do Norte

Os benzodiazepínicos são uma das classes de medicamentos mais utilizadas na prática médica diária, em diversos níveis de atenção. Porém, o crescente uso irracional destas drogas vem desencadeando problemas como dependência/uso abusivo. Na atenção básica tal problemática também está presente, e para melhor enfrentamento dessa realidade, este trabalho propõe estratégias de acompanhamento aos usuários de BZD, através da caderneta básica com dados referentes à saúde do paciente, bem como estimular a participação em atividades terapêuticas não-farmacológicas, com promoção e educação em saúde, como através de um dia de intervenção em espaço comunitário, incluindo palestras educativas com profissionais da saúde sobre BZD, estímulo a atividades físicas e até reeducação alimentar para completar as estratégias de mudança no estilo de vida. Para casos mais graves, deve-se encaminhá-los para avaliação especializada. Espera-se a diminuição em 50% dos casos de dependência/uso abusivo, desde que a participação da equipe de saúde e público-alvo sejam efetivas.

A agricultura familiar do Seridó potiguar: vulnerabilidade, percepção e adaptação às mudanças climáticas

At the semiarid regions of developing countries the rural population has always been vulnerable to the climatic variations e its consequences. The effects of the semiarid climate, together with other biophysics, social and political-economic factors, impair the agricultural production, generating a situation of food insecurity and poverty in the rural areas. With the occurrence of climate change, natural resources of the semiarid regions can became scarcer, what would directly affect the agricultural production and those who depend on it. Therefore, the present study sought to study one of the most susceptible areas to the effects of the semiarid climate and desertification of Rio Grande do Norte, the potiguar s Serido. The study aimed to analyze the socioeconomic and environmental factors that put farmers in a position of vulnerability to the effects of climate; assess their perceptions about climate variations that have already occurred and their knowledge about climate change and global warming, also to identify which adaptation strategies to climate they have adopted at the rural establishment. The survey was conducted in 29 communities of four counties of the potiguar s Serido Caico, Parelhas, Lagoa Nova and Acari. Semi-structured interviews were conducted with local leaders and 241 questionnaires were applied with the family farmers. It was found that in addition to environmental factors such as the scarcity of water resources and climatic conditions, other factors such as the environmental degradation, the small size of the properties, the lack of technical assistance and financial resources and also the low education levels reduce the resilience capacity of family farming to the effects of the Semiarid climate. With the occurrence of climate change, the challenges for family farming at Serido will intensify. If farmers cannot adapt, the impacts may preclude this category of agricultural production causing serious harm to food security and further increasing the vulnerability situation of these populations. Although the farmers perceived changes in climate, the lack resources and information appears as the main reasons preventing the adoption of adaptation strategies. The lack of knowledge about climate change and global warming and the impacts that these phenomena may cause are also limiting factors for adaptation. It is therefore essential to identify the factors that influence the adoption of adaptation strategies, and seek alternatives to living with the semiarid that can strengthen the resilience of family farming and social reproduction that allow agricultural segment, even in a climate change scenario

Análise de estabilidade de falésias na zona costeira de Baía Formosa - RN

The natural and anthropogenic changes that are occurring at the coastal zone around the world represent the greatest problem to society in this century. This problem becomes more evident due to high density of coastal cities, to growing tourist-estate speculation of those areas and to climate change that tend to trigger and accelerate the erosive processes that operating in the littoral. In this context, it‟s possible perceive ever more a significant increase of problems associated to the coastal erosion and retreat of cliffs in the state of Rio Grande do Norte, where this study area of this search is located. The area is located in the coastal zone of the city of Baía Formosa/RN, in south-eastern coast of Rio Grande do Norte, and has a extension of about 1200 meters along the Porto beach. The main objective of this study is to analyze the stability of these cliffs in this region. Through field investigations, testings and computational analysis using the Finite Element Method and Equilibrium Limit Methods. The area was divided into four sections, and were applied checklists, and also realized characterization tests and direct shear tests with materials obtained along these sections. In this manner, it was found that the segments of cliff in this coastal zone have heights around 4 meters to 14 meters and inclinations of approximately 40° to 90°.However the constituents soils of the cliffs were classified, in general terms in accordance to Unified Soil Classification System (USCS), as clayey sands or silty sands, clays of low plasticity, clayey gravels and poorly graduaded sands. The most variegated and clayey soils belong to base of the cliff. The stability analysis showed that the safety factors ranged in section 01, from 1.92 to 4.93, in the section 02, from 1.00 to 1.43, in the section 03, from 1.36 to 1.75 , and section 04, from 1.00 to 3.64. Thus, the sections 02 and 03 were considered more unstable. However, the section 03 can be considered as the most critical section due to the absence of coastal protection structures and the narrow strip of beach.

Transporte longitudinal de sedimento na zona costeira de Natal/RN

The longshore sediment transport (LST) is determinant for the occurrence of morphological changes in coastal environments. Understanding their movement mechanisms and transport is an essential source of information for the project design and coastal management plans. This study aims to characterize, initially, the active hydrodynamic circulation in the study area, comprised of four beach sectors from the south coast of Natal, assessing the average annual LST obtained through three proven equations (CERC, Kamphuis and Bayram et al.), defining the best formulation for the study area in question, and analyze the seasonal variability and the decadal transport evolution. The coastal area selected for this work constitutes one of the main tourist corridors in the city, but has suffered serious damage resulting from associated effects of hydrodynamic forcings and their disorderly occupation. As a tool was used the Coastal Modelling System of Brazil (SMC-Brazil), which presents integrated a series of numerical models and a database, properly calibrated and validated for use in developing projects along the Brazilian coastline. The LST rates were obtained for 15 beach profiles distributed throughout the study area. Their extensions take into account the depth of closure calculated by Harllermeier equation, and regarding the physical properties of the sediment, typical values of sandy beaches were adopted, except for the average diameter, which was calculated through an optimization algorithm based on equilibrium profile formulation proposed by Dean. Overall, the results showed an intensification of hydrodynamic forcings under extreme sea wave conditions, especially along the headlands exist in the region. Among the analyzed equations, Bayram et al. was the most suitable for this type of application, with a predominant transport in the south-north direction and the highest rates within the order of 700.000 m3 /year to 2.000.000 m3 /year. The seasonal analysis also indicated a longitudinal transport predominance in the south to north, with the highest rates associated with the fall and winter seasons. In these periods are observed erosive beach states, which indicate a direct relationship between the sediment dynamics and the occurrence of more energetic sea states. Regarding the decadal evolution of transportation, it was found a decrease in transport rate from the 50’s to the 70’s, followed by an increase until the 2000’s, coinciding with the beginning of urbanization process in some stretches of the studied coastline.

Influência das mudanças climáticas na estrutura funcional da comunidade fitoplanctônica em um reservatório da região do semiárido

The Brazilian Northeast is the most vulnerable region to climatic variability risks. For the Brazilian semi-arid is expected a reduction in the overall rates of precipitation and an increase in the number of dry days. These changes predicted by the IPCC (2007) will intensify the rainfall and droughts period that could promote the dominance of cyanobacteria, thus affecting the water quality of reservoirs, that are most used for water supply, in the semi-arid. The aim of this study was to evaluate the effects of increasing temperature combined with nutrient enrichment on the functional structure of the phytoplankton community of a mesotrophic reservoir in the semi-arid, in the worst case scenario of climate change predicted by the IPCC (2007). Two experiments were performed, one in a rainy season and another in the dry season. In the water sampled, nutrients (nitrate and orthophosphate) were added in different concentrations. The microcosms were submitted to two different temperatures, five-year average of air temperature in the reservoir (control) and 4°C above the control temperature (warming). The results of this study showed that warming and nutrient enrichment benefited mainly the functional groups of cyanobacteria. During the rainy season it was verified the increasing biomass of small functional groups of unicellular and opportunists algae such as F (colonial green algae with mucilage) and X1 (nanoplanktonic algae of eutrophic lake systems). It was also observed an increasing in total biomass, in the richness and diversity of the community. In the dry season experiment there was a greater contribution in the relative biomass of filamentous algae, with a replacement of the group S1 (non-filamentous cyanobacteria with heterocytes) for H1 (filamentous cyanobacteria with heterocytes) in nutrient- enriched treatments. Moreover, there was also loss in total biomass, species richness and diversity of the community. The effects of temperature and nutrients manipulation on phytoplankton community of reservoir Ministro João Alves provoked changes in species richness, the diversity of the community and its functional composition, being the dry period which showed the highest susceptibility to the increase in the contribution of potentially toxic cyanobacteria with heterocytes

Estudo da circulação hidrodinâmica e da dispersão de óleo na zona costeira entre Macau e Galinhos RN

This paper presents a study on coastal hydrodynamics and the spread of an oil spill in waters off Macau and Galinhos, on the east coast of the state of Rio Grande do Norte in Northeast Brazil. This area has a very marked coastal dynamic owing to the complexity of its geomorphological features, developed in a regime of semidiurnal mesotides involving reefs, spits, estuaries, mangroves, lakes and dunes. The region also plays an important role in the socioeconomic development of the state, given that the production of oil, natural gas, salt and shrimp is concentrated there. The series of oil platforms is interconnected by a pipeline system that carries oil to the local terminal. This pipeline could leak at any moment, causing immense ecological damage. To gauge the risks of an oil leak and resulting contamination of the coastal region, two hydrodynamic scenarios were simulated. The results obtained were used to implement a contaminant transport model with the creation of various oil leak scenarios modeled at different volumes (from small to large) and intensities (sporadic and continuous), at points considered critical for the model (on two platforms and at two pipeline intersections), under different wind (summer and winter) and tidal (high and low at new, full and quarter moon phases) conditions. The use of hydrodynamic circulation computer models as a tool for representing a real project design has been increasingly frequent in recent years, given that they enable the realistic simulation of the hydrodynamic circulation pattern in bodies of water and an analysis of the impacts caused by contaminants released into the water. This study used the computer models contained in SisBAHIA®, in continuous development in the area of Coastal Engineering and Oceanography at COPPE/UFRJ

Mudanças climáticas globais e o compromisso pró-ecológico de adolescentes natalenses

In recent years, much has been discussed about global climate changes (GCCs), popularly known as global warming. The scientific evidences point out to the influence of human actions for its drastic intensification. Therefore, studies of the psychological aspects involved become relevant. This study aimed at the investigation of the views of adolescents concerning GCCs, and the possible relations between those views and their pro-ecological commitment. Such commitment is measured by willingness for engagement in pro-environmental behaviors; environmentalism attitudes, like ecocentric and anthropocentric; consideration of future consequences; and ecological worldviews. Participants were 348 adolescents who answered a questionnaire containing questions about socio-demographic data, open questions about the practice of environmental care, and about GCCs, and the scales of Ecocentric and Anthropocentric Environmentalism, the Consideration of Future Consequences and the Ecological Worldviews assessment scale. From the inter-relationships between variables, procedures carried out by means of descriptive and correlacional statistics, it was observed that 55% of teenagers said that they did not engage in actions of environmental care, which was associated with apathyanthropocentric, immediatism, and individualism. The consideration of future consequences joined the practice of environmental care, corroborating evidence from the literature. It was evident that views concerning GCCs were superficial; adolescents perceive it as a generic environmental problem, and are confused with other problems such as pollution. This study found no association between views about GCCs and the indicators of pro-ecological commitment, perhaps due to the conceptual confusion about the subject. However, the lack of environmental care actions and other indicators of non-commitment (apathy-anthropocentric, individualism and immediatism) were associated with conceptually poor or incomplete responses (with no indication of cause, consequence or responsibility for the problem), demonstrating diminished knowledge and the failure to consider these issues

Horticultura no baixo curso do Rio Doce, zona norte do Natal/RN: avaliação da qualidade da água por meio de ensaios ecotoxicológicos

The research is developed in areas of horticulture in the city of Natal, in the neighborhoods of Lagoa Azul, Pajuçara and Redinha, along the Doce River, border area with Extremoz city, Rio Grande do Norte State. The region of the fluvial plain of Doce River is located in an Environmental Protection Zone (ZPA-9). This is one of the ZPA which is not under the regulatory marks and there are several environmental problems caused by use and land occupation, featuring an evident disregard of environmental laws and whose protection is hindered by the lack of specific legal mechanisms. This study aims to provide an overview of the use of pesticides in the lower course of the Doce River, in Natal, Rio Grande do Norte, and to assess environmental degradation in the area through chronic toxicity tests using the microcrustaceous Ceriodaphnia dubia Richard 1894 (Cladocera, Crustacea) as test organism. Visits were made to the area in 2009 and 2010. To obtain information a diagnosis of the local situation was accomplished based on personal observation and non-participatory photographic record, with the aim of assessing the environmental characteristics, population diversity and work processes of horticulturists. During the visits four different points of the Doce River were chosen to collect water for ecotoxicological tests and survey of physico-chemical parameters (dissolved oxygen, pH, chloride, turbidity, conductivity and temperature), which were measured in the field using Multiparameter Probe (TROLL 9500). The adverse effects of pesticide use in the lower course of the Doce River is a major problem for both the environmental and human health, since many of the substances and active principles that enter in the composition of the products are synthesized molecules whose effects can only be evaluated through different studies on their actions and behavior at short, medium or long term

Uso e ocupação do solo e a transformação da paisagem na faixa litorânea da Via Costeira, município de Natal/RN

The coastal area of the city of Natal due to its location and natural potentialities has been an area where we have experienced big changes in its environment, at the expense of several forms of use and human occupation. On the coast of Via Costeira beach the process of use and land occupation was structured at the end of 1970s and early 1980s, as a result of the government policy which has developmental essence, based on the settlement of plenty big enterprises by the Parque das Dunas/Via Costeira Project. This project was created to install in Natal, capital of the state, infrastructure equipment on this stretch of coastline consisted of dune fields and many parts of ecosystems which have high natural relevance and fragility that used to present a semi-isolation in the urban city, for the development of tourist activities, which is considered as a viable economic solution capable of setting right serious socioeconomic problems that had persisted there. According to what was said so far, this study aimed to analyze the forms of use and land occupation besides the change of the landscape along the Via Costeira coast in the city of Natal/RN. These changes often take place without considering the complexity and fragility of natural ecosystems involved. The geoenvironmental study was based on the geosystemic theory, thus It was possible to analyze the human interventions in the superficial aspects of landscapes holistically. The practical procedures were contemplated with literature searches, followed by field work where were fulfilled the recognition and general characterization of the area in order to investigate and analyze the main types of land occupation and its use that have taken place there since big buildings began to come out, being supported by the legislation whose laws are about protection and conservation of coastal natural resources. The research also includes the identification and evaluation of the main types of negative impacts caused due to different forms of use that induce environmental and social conflicts nearby this shore. Thus, It was carried out a spatial and multitemporal analysis from orthophotos, aerial photographs and others taken during the field work besides satellite images too. The information which is taken out from these instruments was used to draw maps related to land occupation, spatial impacts and other thematic maps. We worked on a hypothesis that the implementation of mega enterprises on Via Costeira and many different forms of intensified use by human actions, has not considered the natural aspects and restrictions of use in this area, these ones would be the main factors that brought on the suppression and degradation in this environment and consequently the transformation of the natural landscape.

Projeto político-pedagógico: instrumento de ação educativa na Escola Municipal Ascendino de Almeida Natal-RN (2002-2003)

In this dissertation, we investigate the process of elaboration of the Political-Pedagogical Project in the Municipal School Ascendino de Almeida , situated in the west zone of Natal city, in Rio Grande do Norte State, Brazil. We performed a qualitative research, using information provided by several sources as: interviews carried out in the Municipal Department of Education and also in the mentioned School, document analysis, and literature reviews, mainly with the objective of knowing more about the complexity of this particular reality. This was done in order to establish a mediation between the actual reality and the social, political, and economic context that surrounds it. We analyze the Political-Pedagogical Project according to the visions of Education theoreticians, under the political-normative plan, and also as a process of educational planning that can collaborate significantly for the introduction of changes in school Education. This instrument of the educative action, as a fruit of the participation of the school community, may constitute itself in an important learning instrument of the participation in the social sphere, demanding from the educators the development of complex abilities so that they can construct the Project. In the data analysis, we describe and analyze the process of elaboration of the Political-Pedagogical Project of the mentioned School. We also determine how participation of the school community was constructed as well as the consequences of this envolvement. We also discuss the abilities they needed to develop, the process of studies and dialogues that gave support to the whole process, and the democratic participation in the school decisions, including a dialogical interaction

Shopping-centers :elementos de (re)produção urbana na zona de sul de Natal-RN

This study aims at analysing the (re) prodction of urban space in the south sone of Natal city, in particular the influence of the shopping-centers in this process. In this respect, it also analyses the changes of habits and constumes for part of the society, when those entreprizes were built in better-off areas of the south zone Natal as well as the transformations in the surroundings of the thre main shopping-centers. A sother commercial establishments of the same size, two out of the three main shopping-centers in the city are targered towards the better-off population. However, if compared to the others, one these has, for some time, sought to target a lower in come population. In spite of being an important element in the (re)production of urban space as well as in the cities modern commercial sector, these large commercial entreprizes reinforce capitalisms contradctions in so far as they constitute semi-public space whit an exclusionary and segregatory vatune

Influência das condições ambientais no verdor da vegetação da caatinga frente às mudanças climáticas

The Caatinga biome, a semi-arid climate ecosystem found in northeast Brazil, presents low rainfall regime and strong seasonality. It has the most alarming climate change projections within the country, with air temperature rising and rainfall reduction with stronger trends than the global average predictions. Climate change can present detrimental results in this biome, reducing vegetation cover and changing its distribution, as well as altering all ecosystem functioning and finally influencing species diversity. In this context, the purpose of this study is to model the environmental conditions (rainfall and temperature) that influence the Caatinga biome productivity and to predict the consequences of environmental conditions in the vegetation dynamics under future climate change scenarios. Enhanced Vegetation Index (EVI) was used to estimate vegetation greenness (presence and density) in the area. Considering the strong spatial and temporal autocorrelation as well as the heterogeneity of the data, various GLS models were developed and compared to obtain the best model that would reflect rainfall and temperature influence on vegetation greenness. Applying new climate change scenarios in the model, environmental determinants modification, rainfall and temperature, negatively influenced vegetation greenness in the Caatinga biome. This model was used to create potential vegetation maps for current and future of Caatinga cover considering 20% decrease in precipitation and 1 °C increase in temperature until 2040, 35% decrease in precipitation and 2.5 °C increase in temperature in the period 2041-2070 and 50% decrease in precipitation and 4.5 °C increase in temperature in the period 2071-2100. The results suggest that the ecosystem functioning will be affected on the future scenario of climate change with a decrease of 5.9% of the vegetation greenness until 2040, 14.2% until 2070 and 24.3% by the end of the century. The Caatinga vegetation in lower altitude areas (most of the biome) will be more affected by climatic changes.

Professores em contexto formativo: um estudo do processo de mudanças de concepções sobre o ensino da matemática

El objetivo en esta tesis consistió en estudiar el proceso de los cambios de los conceptos de profesores de la educación infantil y de los años iníciales de la educación básica referente a la enseñanza de la matemática. La investigación se desenvolvió en la escuela Presidente Kennedy, en la ciudad de Natal, en Rio Grande do Norte, teniendo como participante 05 (cinco) profesores del curso normal superior a través de la educación superior del instituto relacionado. El trabajo asocia el programa a él Programa de Pós-Graduação em Educação da Universidade Federal do Rio Grande do Norte, en la base de pesquisa Formação e Profissionalização Docente coordinada de los doctores Betânia Leite Ramalho e Isauro Beltran Núñez. El referencial teórico-metodológico en quien si apoya el trabajo se inserta en la señal conceptual usada por Giordan y de Vecchi (1996), de Carrillo y Contreras (1994), Ramalho; Núñez y Gauthier (2003), Ponte (1998), Guimarães (1988), Ernest (1989). En esta investigación, los conceptos de los profesores habían sido estudiados en el contexto educativo de la formación del nivel superior, usándola reflexiva crítico práctico como estrategia formativa. Estos conceptos se entienden como estructuras subyacentes al pensamiento del profesor. Dado la naturaleza del objeto del estudio, la información, para las intenciones de esta investigación, habían sido cosechados a través de los instrumentos siguientes: cuestionario, plan de la lección, entrevista diaria y del campo. El cuestionario fue constituido de preguntas abiertas y de las entrevistas de la mitad-structuralized. La organización de los datos permitió a La inferencia de los conceptos, usando la técnica de la triangulación de datos. La investigación divulgó que los conceptos de los profesores, a través del proceso formativo, se habían desarrollado de una plataforma para otra, yéndose puesto que los modelos didácticos tradicionales para otros modelos dirigidos a una tendencia didáctica de espontaneísta/investigativa. La reflexión crítica era considerada como elemento catalítico de los cambios de los conceptos de los profesores en la educación de las matemáticas, sin embargo déjenos verifican que estos cambios son difíciles de ocurrir para la naturaleza compleja de estos conceptos. Como facilitadores de los factores de estos cambios, encontramos y el investigativo el trabajo, la dinámica y la naturaleza de las actividades se convirtió en el colaborativo de proceso formativo, entre otros. Como obstáculos a los cambios, identificamos el contexto del trabajo de los profesores, de la cultura de los individualistas prácticos de sus profesores de los colegas, del concepto linear, estático y de los mecánicos de los procesos para enseñar, el conocimiento profesional construído durante la formación inicial, alineación con los modelos didácticos de sus viejos profesores, entre otros

Beirando a vida, driblando os problemas: estratégias de bem viver

The purpose of this study is to analyze the strategies used by families living in at-risk-and-vulnerable situations registered with the Estratégia Saúde da Família (ESF) ( Family Health Strategy ) as they face their daily problems. This is an investigation of a qualitative nature, using interview as the main tool for an empirical approach. Ten women from the Panatis location in northern Natal, Rio Grande do Norte, whose families live in precarious social-economical situations were interviewed. The interviews occurred between the months of April and June, 2007. The reports revealed that a mixture of improvisations and creativity was used as strategies for overcoming the privations and necessities of daily life. We also reached the conclusion that these families sought solutions for their problems through religiosity and a gift reciprocity system as resources for obtaining personal recognition and support in adversity. The results, in addition, point to ESF as one of the strategies used by these families in the search for attention and care. From this perspective, ESF has proven to be a place for listening and the construction of ties that are consolidated through home visits, organized groups, in parties and outings that are promoted in the community, reestablishing contact and support among people and signaling a way out of abandonment and isolation. Holders of knowledge constructed through life experiences, the participants of the study led us to induce and infer the need to amplify space that will allow them to express meanings, values and experiences, and consider that becoming ill is a process that incorporates dimensions of life that go beyond the physical. As health professionals, we need to be aware of the multiple and creative abilities used in the daily lives of these families, so that we can, along with them, reinvent a new way of dealing with health

Conhecimento do enfermeiro sobre as ações de vigilância epidemiológica no Hospital Universitário Onofre Lopes, Natal, RN

This is an exploratory descriptive study with quantitative approach, aiming to verify the nurses' knowledge concerning the epidemiological surveillance activities at the Onofre Lopes hospital (HUOL), in Natal, Rio Grande do Norte. The study was performed with 63 nurses from the hospital and the data were collected through a questionnaire. All data were analyzed using descriptive statistics. The results were discussed and organized into four sections: nurses' knowledge on hospital epidemiological surveillance; procedures of the professional nurse through compulsory notification diseases; difficulties found by nurses to register the compulsory notification diseases and suggestions of strategies to joint epidemiological surveillance service with the care practices of nurses. The results showed that 55.55% of nurses know the main action of epidemiological surveillance, compulsory notification of diseases, and that 42.86% reported to the Hospital Epidemiology Center , while 57.14% did not allocate the information for this service. Most nurses found it difficult to perform notification for not knowing its flow; for the surveillance service does not operate 24 hours and for vagueness on diagnostic of disorders. Suggestions of strategies to improve the quality of epidemiological information are focused on training of nurses in hospital epidemiological surveillance; working in partnership with the surveillance center; diffusion of information on surveillance and conducting a daily active search. It comes to conclusion that most nurses don't notify the Surveillance Center about Compulsory Notification Diseases and it wasn't observed the incorporation of integrality values between the hospital surveillance and all nurses, since this principle guides the actions of health services based on dialogue, listening, ethical commitment, sharing of knowledge among professionals of various services and respect towards other professionals. Therefore, the integrality gap in the actions of the nurses studied, as well as in the surveillance service does not mobilize the potential of such services to changes in the sense of achievement of practices aimed at a special attention model that combines preventive and corrective actions, proposed and desired by SUS. Through the difficulties presented, it becomes important to recommend educational processes with strategy to transform the conducts, besides proposing actions under the principle of integrality provide responses agile and effective, as the purpose of VE hospital emergency care by the current epidemic