As Contradições Do Ciclo De Commodities

The article points out the necessity of better coordinated polices to avoid side effects of the overrating of commodities and stimulate economic growth and domestic employment. Brazil will pay a high price for its posture of leaving behind goals for the long run in favor of profits that might be ephemeral.812331ver Baer, M., Marcos Antonio Macedo, C., (2004) Brasil: investimento estrangeiro direto e estratégias empresariais, , http://www.cepal.org, Para maiores informações, Santiago:Comissão Econômica para a América Latina e Caribe,setembro de (Uma versão simplificada desse trabalho está disponível emBelluzzo, de Mello, L.G., Importações e crescimento anêmico (2007) Valor Econômico,São Paulo, , 6 /02/2007de ver Almeida, J.S.G., de Almeida, D.K., (2008) Para maiores informações, inclusive sobre a metodologia da OCDE O comércio exterior em 2007, , http://www.iedi.org.br, São Paulo:Instituto de Estudos para o Desenvolvimento Industrial, maio de Disponíve

Time Hopping Codes For Optical Cdma Applications

Several code-division multiple access schemes have been proposed for applications in optical communications. Some known codes that have the best auto and cross-correlation properties just supply few distinct sequences, limiting the number of users that can access simultaneously the channel. This paper proposes a new family of unipolar codes that expands the number of available sequences and allows achieving a better biterror rate performance.3283288Chung, F.R.K., Salehi, J.A., Wei, V.K., Optical orthogonal codes: Design, analysis, and applications (1989) IEEE Trans. Inform. Theory, 35, pp. 595-604Salehi, J.A., Code division multiple access techniques in optical fiber networks - Pail I: Fundamental principles (1989) IEEE Trans. Commun., 37, pp. 824-833Salehi, J.A., Bracken, C.A., Code division multiple access techniques in optical fiber networks -Part II: Systems performance analysis (1989) IEEE Trans. Commun., 37, pp. 834-842Azizoglu, M., Salehi, J.A., Li, Y., Optical CDMA via temporal codes (1992) IEEE Trans. Commun., 40, pp. 1162-1170Davies, P.A., Shaar, A.A., Asynchronous multiplexing for an optical-fibre local area network (1983) Electron. Lett., 19 (10), pp. 390-392Shaar, A.A., Davies, P.A., Prime sequences: Quasi-optimal sequences for OR channel code division multiplexing (1983) Electron. Lett., 19 (21), pp. 888-889Brady, D., Verdú, S., A semiclassical analysis of optical code division multiple access (1991) IEEE Trans. Commun., 39, pp. 85-9

Performance Analysis Of Multidimensional Ppm Codes For Optical Cdma Systems In The Presence Of Noise

This paper analyzes the asynchronous error performance of optical code-division multiple access systems utilizing one-dimensional and multidimensional PPM codes in the presence of white Gaussian noise. The effects of the multiple access interference combined with the noise are statistically characterized by continuous probability density functions and, therefore, allowing the investigation on the error performance of the O-CDM A systems employing on-off keying (OOK) and on-off orthogonal (OOO) signaling. For OOK systems, the optimum decision threshold is determined and the error performance degradation due to deviation in the threshold is considered. Furthermore, the performances of the O-CDMA systems using OOK and OOO signaling are compared. © Springer-Verlag 2004.3124312321Stok, Sargent, E.H., The role of optical CDMA in access networks (2002) IEEE Commun. Mag., 40 (9), pp. 83-87Panaro, J.S.G., De Almeida, C., Asynchronous performance of multidimensional PPM codes for optical CDMA systems (2003) Proc. 2nd IASTED Int. Conf. Communication Systems and Networks, pp. 424-429. , Benalmádena, SpainDavies, P.A., Shaar, A.A., Asynchronous multiplexing for an optical-fiber local area network (1983) Electron. Lett., 19 (10), pp. 390-392Shaar, A., Davies, P.A., Prime sequences: Quasi-optimal sequences for or channel code division multiplexing (1983) Electron. Lett., 19 (21), pp. 888-889Park, E., Mendez, A.J., Gasmeiere, E.M., Temporal/spatial optical CDMA networks: Design, demonstration and comparison with temporal network (1992) IEEE Photon. Tech. Lett., 4, pp. 1160-1162Tancevski, L., Andonovic, I., Tur, M., Budin, J., Hybrid wavelength hopping/time spreading code division multiple access systems (1996) Proc. IEE-Optoelectron., 143 (3), pp. 161-166Shivaleela, E.S., Sivarajan, K.N., Selvarajan, A., Design of a new family of two-dimensional codes for fiber-optic CDMA networks (1998) J. Light. Tech., 16 (4), pp. 501-508Chang, T.W.F., Sargent, E.H., Optical CDMA using 2-D codes: The optimal single-user detector (2001) IEEE Comm. Lett., 5 (4), pp. 169-171Papoulis, (1991) Probability, Random Variables, and Stochastic Processes, , Singapore: McGraw-Hill, ch. 5Abramowitz, M., Stegun, I.A., (1972) Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, pp. 299-300. , New York: Dove

Pharmacogenetics and clinical characteristics of patch test confirmed patients with Abacavir hypersensitivity

No abstract availabl

Permanências e mutações na definição intergeracional do trabalho infantil Continuities and mutations in the intergenerational definition of child labor

O artigo discute a percepção de famílias dos grupos populares sobre o significado do trabalho infantil, apontando o enquadramento moral, cercado de ambiguidades, das decisões tomadas pela geração mais velha de adiar a entrada dos filhos em ocupações remuneradas. Embora suas decisões possam ser explicadas, pelo menos em parte, pela profundidade das transformações nas mentalidades que acompanharam a gênese da percepção da criança como um ser humano em formação e fundamentaram a transformação do trabalho infantil em prática ilegal e socialmente ilegítima, nosso estudo, não obstante, ajuda a mostrar que as ambiguidades percebidas podem ser explicadas pela história social das gerações em foco, que é, em grande parte, a história das transformações por que passou o Brasil nas últimas décadas, tanto no que diz respeito à sua estrutura produtiva, quanto à sua organização legal e espacial.<br>This paper discusses how low-income families perceive the meaning of child labor. It points out the ambiguous moral vision that supports the decision made by the older generation to postpone the entrance of their children in the labor market. Such decisions can be explained, at least partly, by the deep transformations in mentalities that have followed the genesis of the perception of children as "human beings in formation" and founded the transformation of child labor into an illegal and socially illegitimate practice. Nevertheless, our study shows that the ambiguities noted may also be explained by the social history of the generations focused, which is, mainly, the history of the transformations that have taken place, these last decades, in the productive structures and in the legal and spatial organization of Brazil

Purificação e caracterização de alfa-galactosidases de sementes de Platymiscium pubescens Micheli Purification and characterization of alpha-galactosidases from Platymiscium pubescens Micheli seeds

Este trabalho objetivou foi determinar a composição bioquímica de sementes de espécies florestais e caracterizar a enzima alfa-galactosidase de sementes germinadas de Platymiscium pubescens. Os maiores teores de lipídios foram determinados em sementes de Chorisia speciosa, Caesalpinia peltophoroides, Tabebuia serratifolia e Tabebuia velanedae, enquanto sementes de Enterolobium contortisiliquum, Schizolobium parahyba e Cassia grandis apresentaram os maiores teores protéicos. A alfa-galactosidase catalisa a hidrólise dos oligossacarídeos de rafinose, em sementes de leguminosas, durante a germinação. A maior atividade da alfa-galactosidase foi detectada em sementes de Platymiscium pubescens após 72 h de embebição. Duas formas de alfa-galactosidases, C1 e C2, foram purificadas de sementes germinadas de P. pubescens, usando-se fracionamento com sulfato de amônio e cromatografias de filtração em gel e de afinidade. Essas enzimas apresentaram atividade máxima em pH 5,5 e a 50-55 ºC. Os valores de Km ap das formas C1 e C2, para o substrato ro-nitrofenil-alfa-D-galactopiranosídeo, foram de 0,54 mM e 0,78 mM, e para a rafinose, de 4,64 mM e 5,09 mM, respectivamente. Essas enzimas exibiram estabilidade térmica moderada, mantendo 70% da atividade original após 3 h de incubação a 45 ºC. A atividade enzimática da C1 e C2 foi totalmente perdida na presença de CuSO4 e dodecil sulfato de sódio (SDS). Tais enzimas também hidrolisaram melibiose, rafinose e estaquiose, indicando potencial para aplicações biotecnológicas.<br>The objective of this work was to determine seed biochemical composition of forest species and to characterize alpha-galactosidase enzyme of germinated seeds of Platymiscium pubescens. The highest lipid levels were found in seeds of Chorisia speciosa, Caesalpinia peltophoroides, Tabebuia serratifolia and Tabebuia velanedae, whereas seeds of Enterolobium contortisiliquum, Schizolobium parahyba and Cassia grandis showed the highest protein levels. alpha-galactosidase catalyzes the hydrolyzis of raffinose oligossacarides in legume seeds during germination. The highest activity of alpha-galactosidase was found in seeds of Platymiscium pubescens after 72 h of soaking in the water. Two forms of alpha-galactosidases, C1 and C2, were purified from germinated seeds of P. pubescens, using partition with ammonium sulfate, and gel filtration and affinity chromatographies. These enzymes presented maximum activity at pH 5.5, 50-55ºC. Km ap values in the C1 and C2 forms forrho-nitrophenyl-alpha-D-galactopyranoside substrate were 0.54 mM and 0.78 mM, and 4.64 mM and 5.09 mM for raffinose, respectively. These enzymes showed moderate thermal stability, maintaining 70% of the original activity after 3 h incubation at 45ºC. The C1 and C2 enzymatic activity was totally lost in the presence of CuSO4 and sodium dodecyl sulfate (SDS). These enzymes also hydrolyzed melibiose, raffinose and stachyose, indicating a potential for biotechnological applications