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- Universidade Aberta de Portugal
- Repositório Científico Lusófona
- IGI Global
- De Gruyter
- Mirjana Pejic Bach University of Zagreb
- Instituto Superior de Economia e Gestão
- NSBE - UNL
- Banco Mundial
- Inderscience
- Universiti Malaysia Sarawak
- Society of Alliance, Fidelity and Advancement
- World Bank, Washington, DC
- World Bank Group, Washington, DC
- Arts et Métiers ParisTech
- Universidade Federal do Rio Grande do Sul
- Elsevier
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‣ Balancing european SME managers’ training contents : perceived importance & training needs
Fonte: Universidade Aberta de Portugal
Publicador: Universidade Aberta de Portugal
Tipo: Artigo de Revista Científica
Publicado em //2014
Português
Relevância na Pesquisa
37.260017%
Background: Given the limited available time of in-service professionals, the balance
between the perceived importance of the course content and training needs is
essential for the acceptance and attractiveness of training courses aimed at them.
Objectives: The goal of the paper is to contribute to the development of
entrepreneurship and business training programs for European SME managers.
Methods/Approach: In six European countries a survey focusing on SME managers’
views on the importance of individual items from a list of potential course content
items, and their training needs was carried out, and followed by an analysis using
exploratory and multivariate techniques. It was aimed at identifying homogeneous
groups of managers with common training needs and perceptions of content
importance. Results: Homogeneous groups of managers who assign the same
importance to certain competences and who have common training needs are
identified. Conclusions: Results of our research could help training institutions to
develop courses aimed at SME managers. The balancing approach proved to be an
interesting method of combining conflicting requirements for the training course
curriculum development.
Link permanente para citações:
‣ Integrated information systems in polish SME sector
Fonte: Repositório Científico Lusófona
Publicador: Repositório Científico Lusófona
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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As shows statistical data and Author’s personal experience, only 10% of Polish SME managers understands the idea of Integrated Information Systems (IIS) and is aware of potential benefits. Giving some business trainings for middle level management (focused mainly on company controlling functions) Author found that participants knew the ERP only as the name and most of them were convinced, that they are using such a solution in their enterprises. The idea of training was to present today top ERP (Enterprise Resource Planning) solutions in the form of professional presentation given by SAP Business One, Microsoft Dynamics AX and Polish most commonly used Comarch CDN Optima. The goal of this article is to present basic knowledge concerning Integrated Information Systems in the domain of its evolution, implementation methods and present situation of ERP usage among SME.The final part is a case study of ERP system selection process for metal construction company in Szczecin (Poland).
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‣ SME innovation in Poland – policy and Institutional Environment
Fonte: ISG
Publicador: ISG
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.155708%
Innovation of Polish economy as assessed by international institutions (OECD, EU) is below the average for EU- 27 although one must note the progress from the group of catching up countries to that of moderate innovators (2010).
Summary Innovation Index (SII) for Poland is lower than the average for all the EU member states but its growth rate is higher than the EU average. Monitoring of innovation indexes for Polish economy does not give a clear-cut picture of the progress made as changes follow different directions. Dynamics of innovation outlays is one among positive symptoms.
Businesses operating in Poland allocate more and more resources for innovation. Small and medium-sized enterprises (SME) constitute the core of Polish economy. They represent 99.8% of all economic operators, employ 70.1% of the working population, generate 47.7% of the GDP and become increasingly active in innovation. When it comes to the latter one of its key conditioning factors are innovation policy pursued by the state and institutional environment. That environment consists of the network of training and advisory centres, technology transfer centres, incubators, technological parks and financial instruments
that support enterprise and innovation. The main objective of the paper is to study the institutional environment and state policy as fundamental factors that impact the increase in SME innovation in Poland.
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‣ Rvolta, a case for open innovation : how can a SME be innovative in a competitive industrial environment
Fonte: IGI Global
Publicador: IGI Global
Tipo: Parte de Livro
Publicado em /01/2012
Português
Relevância na Pesquisa
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#Open innovation#SME#Pilot enterprises#Networks#Business management#Interactions#It and work processes#Waste management industry
Rvolta has been working in waste management industry for 16 years now. This SME (Small and Medium Enterprise) from Portugal is taken as a focus point for the case study addressing a network of partners working in various activities which became related, so as to disclose the underlying innovative spirit, strategy and partnership structure. Objectives of the present chapter are to portray and analyze a SME success case in open innovation (through various innovation practices), and clarify how knowledge creation and collaboration amongst different players in a network takes place. An exemplary collaboration episode is told. Framing issues are addressed so as to understand how they affect open innovation in SMEs. The study finds interactions, networking, and partnership connections, are important issues and indeed make a difference, thus enabling SMEs to innovate. This case evolved from an exploratory phase of an Information Systems PhD qualitative research, addressing open and crowdsourcing innovation.
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‣ Balancing European SME managers’ training contents : perceived importance & training needs
Fonte: De Gruyter
Publicador: De Gruyter
Tipo: Artigo de Revista Científica
Publicado em //2014
Português
Relevância na Pesquisa
37.260017%
Background: Given the limited available time of in-service professionals, the balance between the perceived importance of the course content and training needs is essential for the acceptance and attractiveness of training courses aimed at them. Objectives: The goal of the paper is to contribute to the development of entrepreneurship and business training programs for European SME managers. Methods/Approach: In six European countries a survey focusing on SME managers’ views on the importance of individual items from a list of potential course content items, and their training needs was carried out, and followed by an analysis using exploratory and multivariate techniques. It was aimed at identifying homogeneous groups of managers with common training needs and perceptions of content importance. Results: Homogeneous groups of managers who assign the same importance to certain competences and who have common training needs are identified. Conclusions: Results of our research could help training institutions to develop courses aimed at SME managers. The balancing approach proved to be an interesting method of combining conflicting requirements for the training course curriculum development.
Link permanente para citações:
‣ Balancing European SME Managers’ Training Contents: Perceived Importance and Training Needs
Fonte: Mirjana Pejic Bach University of Zagreb
Publicador: Mirjana Pejic Bach University of Zagreb
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.260017%
Given the limited available time of in-service professionals, the balance between the perceived importance of the course content and training needs is essential for the acceptance and attractiveness of training courses aimed at them. Objectives: The goal of the paper is to contribute to the development of entrepreneurship and business training programs for European SME managers. Methods/Approach: In six European countries a survey focusing on SME managers’ views on the importance of individual items from a list of potential course content items, and their training needs was carried out, and followed by an analysis using exploratory and multivariate techniques. It was aimed at identifying homogeneous groups of managers with common training needs and perceptions of content importance. Results: Homogeneous groups of managers who assign the same importance to certain competences and who have common training needs are identified. Conclusions: Results of our research could help training institutions to develop courses aimed at SME managers. The balancing approach proved to be an interesting method of combining conflicting requirements for the training course curriculum development.
Link permanente para citações:
‣ Relationship leading and SME financingin the Azores
Fonte: Instituto Superior de Economia e Gestão
Publicador: Instituto Superior de Economia e Gestão
Tipo: Dissertação de Mestrado
Publicado em //2014
Português
Relevância na Pesquisa
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#Relacionamento Bancário#PME#Assimetria informacional#Financiamento bancário#Relationship Lending#SME#Information asymmetry#Bank finance
Mestrado em Ciências Empresariais; Pequenas e médias empresas desempenham um papel importante na economia mundial. No entanto, a elevada dificuldade em aceder aos fundos necessários muitas vezes limita o crescimento destas empresas. Este estudo tem como propósito analisar alguns dos mais debatidos problemas no que a financiamento de PMEs diz respeito, particularmente Relacionamento Bancário e dificuldades no acesso ao financiamento. Posteriormente, realiza um exercício comparativo entre a percepção de PMEs na Região Autónoma dos Açores e as mais comuns considerações presentes na literatura. A maioria dos inquiridos considera que o acesso ao financiamento bancário é difícil, e percepciona os critérios relacionados com garantias e com o histórico de crédito da empresa como os mais importantes para as decisões de concessão de crédito dos bancos. A maioria dos inquiridos considera igualmente estar envolvido em Relacionamento Bancário, retirando benefícios dessa relação.; Small and medium enterprises are crucial for economies all around the globe. However, their growth is constrained by strong difficulties in accessing the funds they imperatively need. This study reviews some the most common issues regarding SME finance...
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‣ Innovation at Polisport: Discoverding the drivers and impact on performance at a Portuguese SME
Fonte: NSBE - UNL
Publicador: NSBE - UNL
Tipo: Dissertação de Mestrado
Publicado em /06/2012
Português
Relevância na Pesquisa
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics; This case intends to study the drivers of innovation at Polisport, a Portuguese SME operating in the plastics industry for two-wheeled vehicles. This firm has won several product awards across the world and was consider in 2011 the most innovative SME in Portugal. Embodying innovation Polisport has been able to conquer international markets, transform its industry and outplay established competitors despite its smaller resources. The goal is to discover a set of relevant variables that positively affect its innovativeness and analyzing the impact of the innovation strategy on firm’s performance.
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‣ Evaluating SME Support Programs in Chile Using Panel Firm Data
Fonte: Banco Mundial
Publicador: Banco Mundial
Português
Relevância na Pesquisa
37.39231%
#ACCOUNTING#BENEFICIARIES#BUSINESS DEVELOPMENT#BUSINESS DEVELOPMENT SERVICES#BUSINESS ENVIRONMENT#CONSUMER PRICE INDEX#CONTROL GROUPS#COUNTERFACTUAL#CREDIT LINES#ECONOMIC SECTORS#EMPLOYMENT
This paper evaluates small and medium
enterprise (SME) support programs in Chile using a
firm-level panel for the 1992-2006 period on two groups of
firms a treatment group that participated in SME programs
and a control group that did not. These unique panel data
provide an unprecedented opportunity to address several
issues that have plagued impact evaluations of SME programs
selectivity bias from observed and unobserved firm
heterogeneity, identification of an appropriate control
group, and inability to track firms over a long enough
period of time for performance outcomes to be realized.
Using difference-in-differences models combined with
propensity score matching methods, the paper finds evidence
that participation in SME programs in Chile is associated
with improvements in intermediate outcomes (training,
adoption of new technology and organizational practices),
and causally with positive and statistically significant
impacts on sales, production, labor productivity, wages and
exports. The mixed results of previous studies may be
attributable in part to the confounding effects of
unobserved heterogeneity motivating selection into programs
of firms with relatively low productivity levels...
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‣ Understanding Business Success through the Lens of SME Founder-Owners in Australia and Malaysia
Fonte: Inderscience
Publicador: Inderscience
Tipo: Artigo de Revista Científica
Publicado em //2009
Português
Relevância na Pesquisa
37.00173%
Given the lack of consensus on how to measure success, this paper
explores the meaning of business success as perceived by SME business owners in Australia and Malaysia. A qualitative methodology was adopted whereby semi structured interviews were conducted with ten entrepreneurs from each country. A content analysis of the interview data identified 20 criteria for defining success, broadly categorised into:
1 financial
2 lifestyle
3 social responsibility
4 customer satisfaction criteria clusters.
Interestingly, the answers provided by Australian entrepreneurs were largely similar to the Malaysians. However, slight differences relating to aspects of financial, lifestyle and social responsibility were identified. Overall, this study finds evidence for the utilisation of multidimensional measures of business success in Australia and Malaysia.; Ahmad N. and Seet P-S; Copyright (c) 2009 Inderscience Enterprises
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‣ Gender variations in ethical and socially responsible considerations among SME entrepreneurs in Malaysia
Fonte: Universiti Malaysia Sarawak
Publicador: Universiti Malaysia Sarawak
Tipo: Artigo de Revista Científica
Publicado em //2010
Português
Relevância na Pesquisa
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The rise in ethics and social responsibility scrutiny has attracted a lot of debate pertaining to the prevalence of such practices in SMEs. Concomitantly, the emergence of women participation in new ventures has raised interest among the researchers to examine the gender variations in regards to ethical and social responsibility considerations in business given that there is evidence suggesting women are generally more ethical than men. The present study attempts to explore the prevalence of such practices among Malaysian SME entrepreneurs and subsequently examine the gender differences in terms of the importance placed by female and male entrepreneurs in regards to these practices. A sequential mixed-method design was employed. The first phase involved a series of interviews conducted with ten SME entrepreneurs. Subsequently, in the second phase, survey was employed whereby 212 SME entrepreneurs operating in both manufacturing and service sectors participated in the study. Descriptive statistics analysis and an independent sample t-test were conducted to generate answers to the research questions. The findings indicate that ethical and socially responsible practices were perceived important by the entrepreneurs; however, there are gender variations in regards to the magnitude of such practices in their business activities. It appears that women perceived ethics and social responsibility conducts as more important than their male counterparts in managing their business. Given such findings...
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‣ A cross-cultural insight into the competency-mix of SME entrepreneurs in Australia and Malaysia
Fonte: Society of Alliance, Fidelity and Advancement
Publicador: Society of Alliance, Fidelity and Advancement
Tipo: Artigo de Revista Científica
Publicado em //2011
Português
Relevância na Pesquisa
37.260017%
This paper attempts to unearth the competency-mix required by entrepreneurs in Australia and Malaysia in order to sustain their ventures. Based on this premise, the present study aims to identify, validate, and compare the competencies perceived to be important by SME entrepreneurs operating in both countries. This involved determining the psychometric rigor of the model and establishing the psychometric properties of the model of entrepreneurial competency using a sample of 391 SME entrepreneurs. Interestingly, it was found that some competencies are context-free while others are culture-specific. The identification of competencies that are highly prevalent in Australia and Malaysia would assist in the development of an assessment index that could be use in training and development programs for practicing as well as prospective SME entrepreneurs.; http://search.informit.com.au/documentSummary;dn=851764310084321;res=IELBUS; Noor Hazlina Ahmad, Carlene Wilson and Liz Kummerow
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‣ Competitive Small and Medium Enterprises : A Diagnostic to Help Design Smart SME Policy
Fonte: World Bank, Washington, DC
Publicador: World Bank, Washington, DC
Tipo: Economic & Sector Work :: Knowledge Economy Study; Economic & Sector Work
Português
Relevância na Pesquisa
37.526772%
#ADVERTISING#BALANCE SHEETS#BANK LOANS#BARRIERS TO ENTRY#BEST PRACTICE#BUSINESS ACTIVITIES#BUSINESS ASSOCIATION#BUSINESS CLIMATE#BUSINESS ENTRY#BUSINESS ENVIRONMENT#BUSINESS FORMATION
Small and medium-sized enterprises
(SMEs) account for a lion's share of the enterprises in
most economies and are also thought to be an engine of new
growth and innovation. The focus of this paper is to take
the insights on SME mix and segments to practical
implications for developing countries around the world. The
paper attempts to do this by providing a diagnostic approach
that client countries and regions can use to assess their
SME sectors and tease out firms' contribution to the
local economy. Guidelines and specific examples of policies
based on the insights in the paper have been provided.
Lastly, the paper includes some areas of future research
that are required on the subject. This paper proceeds in
three steps. The first is to better understand the economic
contribution of SMEs. This analysis complements the existing
policy focus and takes it further to direct attention to a
more specific set of growth drivers to enable the firms that
matter disproportionately, the competitive SMEs, while
remaining inclusive and avoiding market distortion. The
second step is to develop a perspective on how best to
complement the policy focus on competitive SMEs with that on
larger firms. Policy-makers need to structure policy
appropriately to develop a healthy eco-system of firms. The
third step is to make this analysis actionable by
policy-makers. This paper provides an initial SME policy
diagnostic. A better understanding of how to encourage SME
growth has the potential to make a substantial contribution
to national economic performance.
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‣ Helping Local SME Suppliers Survive the Global Economic Crisis : Lessons from Zambia
Fonte: World Bank, Washington, DC
Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Brief; Publications & Research
Português
Relevância na Pesquisa
37.39231%
#COMMODITY PRICES#COMPANY#COMPETITIVENESS#COPPER PRICE#COPPER PRICES#CORPORATIONS#CREDIT LINES#DIVERSIFICATION#DOWNSIZING#FIRMS#JOB LOSSES
Economies dependent on resource
extraction are particularly susceptible to sudden swings in
commodity prices. International Finance Corporation (IFC)
linkages projects should take this into account by helping
small and medium enterprises (SMEs) prepare for the
'hard times,' such as the current global economic
crisis, through diversification of markets and improving
their coping capacities. To reduce their dependency on one
or a limited number of corporations, SMEs should also be
linked or introduced to market opportunities available from
other organizations or firms. Likewise, other players or
consumers in the sector should be included in
'crisis' planning and introduced to SMEs to
increase the market size for SMEs. Finally, partnerships
should be sought with government organizations involved in
SME development to design innovative capacity-building
interventions. This smart lesson describes how IFC's
are helping Zambian SME suppliers hit hard by the global
economic crisis and sharp fall in world copper prices and
the lessons learned from the experience.
Link permanente para citações:
‣ SME Solutions Center—Kenya : Developing Alternative Financing Solutions for Small and Medium Enterprises
Fonte: World Bank, Washington, DC
Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Brief; Publications & Research
Português
Relevância na Pesquisa
37.502163%
#ACCESS TO FINANCE#ACCESS TO RESOURCES#ACCESS TO SERVICES#ADVISORY SERVICES#ALTERNATIVE FINANCING#APPROVAL RATE#BANK LOANS#BANKING SECTOR#BANKS#BENEFICIARY#BUSINESS ASSOCIATIONS
Small and medium enterprises (SMEs) in
Africa have been hailed as the engine of economic growth.
They are at the heart of developing countries'
entrepreneurship, the source of most new employment and
productive investment, and the basis for growth and poverty
reduction. Despite the economic potential of SMEs, they face
severe constraints related to access to resources, finance,
and services, as well as procedural barriers all of which
limit their potential to invest, innovate, and improve
productivity and sustainability. To address these
constraints, International Finance Corporation (IFC)
developed the SME Solutions Centre (SSC) Pilot Program in
Kenya. The SSC value proposition centers on four key
pillars: access to finance, access to advisory
services/technical assistance (now SME management
solutions), access to reliable market information, and
support for an enhanced business enabling environment. This
smart lesson details the lessons learned from the SSC's
experience with the access to finance pillar.
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‣ Garanti Bank SA : Combining SME Banking Excellence with a Proposition for Women Entrepreneurs in Turkey
Fonte: World Bank Group, Washington, DC
Publicador: World Bank Group, Washington, DC
Tipo: Publications & Research :: Working Paper; Publications & Research
Português
Relevância na Pesquisa
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#ACCESS TO CAPITAL#ACCESS TO FINANCE#ACCOUNTING#AFFILIATES#APPLICATION PROCESS#ASSET MANAGEMENT#AUTO LOAN#BANK BRANCHES#BANKS#BEST PRACTICES#BORROWING
Garanti Bankasi (Garanti) is a regional
pioneer in offering products and services specifically
targeted towards women entrepreneurs as a specific market
segment. In 2006, Garanti created a women's entrepreneur
support package specifically designed to help Turkey s women
entrepreneurs to establish and grow their businesses. This
was followed up with the creation of Women Entrepreneur
Gatherings, in 2007, which provided additional training and
educational tools and new networking opportunities. And in
2013, Garanti began collaborating with Bogazici University,
a top university in Turkey, to offer an intensive mini-MBA
training program for women entrepreneurs. Garanti also
launched Turkey s first Woman Entrepreneur of the Year
award, an initiative that showcases women who have
successfully grown their business, encouraging more women
entrepreneurship in the country. This case study (the
study ) explores how Garanti leaders decided to focus on
women entrepreneurs. It also documents and analyzes the
bank s efforts to build a profitable and sustainable women
in business franchise...
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‣ Integration of an eco-design process within an SME: knowledge feedback on a recent development of a new range of hospital carts
Fonte: Inderscience
Publicador: Inderscience
Português
Relevância na Pesquisa
37.00173%
#eco-design#new product development#environmental aspects#npd#sustainable process#knowledge feedback#sme#Sciences de l'environnement: Ingénierie de l'environnement#Sciences de l'ingénieur: Matériaux#Sciences de l'ingénieur: Mécanique#Sciences de l'ingénieur: Mécanique: Génie mécanique
Nowadays, in order to face increasing competition, businesses must differentiate through innovation, but also crucially by positioning themselves with respect to environmental concerns, in order to improve brand image. SMEs are particularly plagued with a lack in human, financial and time resources to integrate such aspects to design. In this paper, we propose a gradual approach (short-, medium- and long-term) to implement an eco-design process in SMEs. This process comprises four stages: analysis, sensitisation, eco-design strategy and sustained improvement. A first experimentation, in collaboration with a SME (MulTiroir-Controlec), allowed us to integrate this eco-design process in the development of a new product range of hospital carts. We present the results of the product development as well as an experience feedback on the project; today the company integrates this eco-design approach in its strategy.
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‣ Adaptation and implementation of a process of innovation and design within a SME
Fonte: Arts et Métiers ParisTech
Publicador: Arts et Métiers ParisTech
Português
Relevância na Pesquisa
37.155708%
#Innovation#Design#SME#Functional bases#Sciences de l'ingénieur: Mécanique#Sciences de l'ingénieur: Mécanique: Génie mécanique
A design process is a sequence of design phases, starting with the design requirement and leading to a definition of one or several system architectures. For every design phase, various support tools and resolution methods are proposed in the literature. These tools are however very difficult to implement in an SME, which may often lack resources. In this article we propose a complete design process for new manufacturing techniques, based on creativity and knowledge re-use in searching for technical solutions. Conscious of the difficulties of appropriation in SME, for every phase of our design process we propose resolution tools which are adapted to the context of a small firm. Design knowledge has been capitalized in a knowledge base. The knowledge structuring we propose is based on functional logic and the design process too is based on the functional decomposition of the system, and integrates the simplification of the system architecture, from the early phases of the process. For this purpose, aggregation phases and embodiment are proposed and guided by heuristics.
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‣ Atividade física para idosos em Porto Alegre : um estudo dos programas da Fundação de Assistência Social e Cidadania - FASC e da Secretaria Municipal de Esporte, Recreação e Lazer - SME
Fonte: Universidade Federal do Rio Grande do Sul
Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação
Formato: application/pdf
Português
Relevância na Pesquisa
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#Fundação de Assistência Social e Cidadania - FASC.#Physical activity#Elder people#Porto Alegre. Secretaria Municipal de Esporte, Recreação e Lazer - SME.#Atividade física#Public policy#Idoso#Esportes#Organizacao e politicas governamentais#Esportes : Organização & administração#Porto Alegre (RS)
O estudo teve por objetivo investigar os programas de atividade física para idosos desenvolvidos pela Prefeitura de Porto Alegre, RS. Foram pesquisadas a Fundação de Assistência Social e Cidadania - FASC e a Secretaria Municipal de Esportes, Recreação e Lazer – SME, instituições responsáveis pelo planejamento e execução dos programas de atividades física para idosos na cidade. Estes programas atendem cerca de 3500 pessoas, organizados em 58 grupos. São oferecidas atividades de ginástica, alongamento, jogos adaptados, dança e caminhadas. O estudo foi de natureza qualitativa do tipo descritiva com amostra intencional. Para a coleta das informações utilizou-se entrevista semi-estruturada, análise documental e questionário. Foram entrevistados 14 coordenadores e 7 professores. Na análise documental, foram pesquisados 28 documentos, entre projetos, resoluções, material informativo e relatórios. O questionário com questões abertas e fechadas foi aplicado em 205 pessoas. Foram construídos níveis de análise para as entrevistas e a avaliação dos documentos. Os dados dos questionários foram tratados estatisticamente com o Software SPSS e utilizados procedimentos não paramétricos de análise, freqüências e porcentagens. Os resultados indicaram que a falta de recursos humanos e materiais interfere na implementação dos programas. O número de participantes nas atividades físicas é ainda inexpressivo frente à população idosa de Porto Alegre. Isto faz com que os programas não sejam caracterizados como uma política abrangente. Com relação às ações preventivas de doenças crônico-degenerativas que atingem os idosos...
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‣ α-sulfur or α-fluorine ̶ Which is more stabilizing for a carbocation? A computational study of electrophilic addition to HFC=CH(SMe) and FC(R1)=CR2(SMe) and related model systems
Fonte: Elsevier
Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion
Formato: application/pdf
Português
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#ALPHA-F VERSUS ALPHA-SME#FLUOROCARBENIUM ION#THIOCARBENIUM ION#THIIRANIUIM ION#Charge delocalization#DFT#Físico-Química, Ciencia de los Polímeros, Electroquímica#Ciencias Químicas#CIENCIAS NATURALES Y EXACTAS
Carbocations derived from protonation, methylation, and bromine addition to HFC55CH(SMe) (1) were studied by DFT [B3LYP/6-31G*, B3LYP/6-311G(3df,p), and B3LYP/aug-cc-pVTZ] and by MP2/6-31G* to examine relative carbocation stabilizing effects of a-SMe versus a-fluorine. The a-SMe carbocations 1aE+ and the unsymmetrical thiiranium ions 1cE+ were found to be considerably more stable than the corresponding a-fluorocarbenium ions 1bE+ . Study of protonation and methylation of FC(R1)55CR2(SMe) [R1 = H, R2 = SMe (2); R1 = F, R2 = H (3); R1 = F, R2 = SMe (4); R1 = Me, R2 = H (5); R1 = Me, R2 = SMe (6)] by B3LYP/6-31G* identified the corresponding unsymmetrical thiiranium cations as lowest energy minima, followed closely by the a-thiocarbenium ions. With 2, 4, and 6, skeletally rearranged a-thiocarbenium ions are formed by SMe migration. The a-SMe and the thiiranium cations are also favored relative to a- fluorocarbenium ions in protonation and methylation of the cyclic analogs 8 and 9. Computed NPA charges and the GIAO-derived 13C and 19F NMR chemical shifts underscore the significance of athiocarbocations and thiiranium ions in electrophilic addition to FC(R1)55CR2(SMe).; Fil: Laali, Kenneth K.. University of North Florida. Department of Chemistry; Estados Unidos de América;; Fil: Borosky...
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