Tratado de Libre Comercio Colombia–Canadá. Ventajas y desafíos en materia de inversiones

This paper describes and analyzes the Free Trade Agreement between Canada and Colombia, as well as its precedents in in- vestment issues. The research methodology used for this paper includes content analysis and documentary research about the FTA and their respective rounds of negotiation. The results shown that Colombia has attractive sectors for Canadian capital invest- ment such the mining sector, real state and financial services. Meanwhile, for Colombia the agreement will allow a more com- petitive country for the international market and will increase the confidence for overseas.Este documento desarrolla un análisis descriptivo del Tratado de Libre Comercio suscrito entre Canadá y Colombia, y sus antece- dentes en materia de inversiones. Para ello se utiliza la metodolo- gía de investigación documental y análisis de contenidos del TLC y sus respectivas rondas de negociación. Los resultados muestran que Colombia tiene sectores atractivos para la inversión de capital canadiense, como es el caso de los sectores minero, inmobiliario y de servicios financieros. Por su parte, este acuerdo le permitirá a Colombia ser más competitivo en el mercado internacional y mejorar la confianza inversionista a nivel mundial

Low Temperature Static and Dynamic Behavior of the Two-Dimensional Easy-Axis Heisenberg Model

We apply the self-consistent harmonic approximation (SCHA) to study static and dynamic properties of the two-dimensional classical Heisenberg model with easy-axis anisotropy. The static properties obtained are magnetization and spin wave energy as functions of temperature, and the critical temperature as a function of the easy-axis anisotropy. We also calculate the dynamic correlation functions using the SCHA renormalized spin wave energy. Our analytical results, for both static properties and dynamic correlation functions, are compared to numerical simulation data combining cluster-Monte Carlo algorithms and Spin Dynamics. The comparison allows us to conclude that far below the transition temperature, where the SCHA is valid, spin waves are responsible for all relevant features observed in the numerical simulation data; topological excitations do not seem to contribute appreciably. For temperatures closer to the transition temperature, there are differences between the dynamic correlation functions from SCHA theory and Spin Dynamics; these may be due to the presence of domain walls and solitons.Comment: 12 pages, 14 figure

Theory of interlayer exchange interactions in magnetic multilayers

This paper presents a review of the phenomenon of interlayer exchange coupling in magnetic multilayers. The emphasis is put on a pedagogical presentation of the mechanism of the phenomenon, which has been successfully explained in terms of a spin-dependent quantum confinement effect. The theoretical predictions are discussed in connection with corresponding experimental investigations.Comment: 18 pages, 4 PS figures, LaTeX with IOP package; v2: ref. added. Further (p)reprints available from http://www.mpi-halle.de/~theory

Vacuum fluctuation forces between ultra-thin films

We have investigated the role of the quantum size effects in the evaluation of the force caused by electromagnetic vacuum fluctuations between ultra-thin films, using the dielectric tensor derived from the particle in a box model. Comparison with the results obtained by adopting a continuum dielectric model shows that, for film thicknesses of 1-10 nm, the electron confinement causes changes in the force intensity with respect to the isotropic plasma model which range from 40% to few percent depending upon the film electron density and the film separation. The calculated force shows quantum size oscillations, which can be significant for film separation distances of several nanometers. The role of electron confinement in reducing the large distance Casimir force is discussed

Thermal Stability of the Human Immunodeficiency Virus Type 1 (HIV-1) Receptors, CD4 and CXCR4, Reconstituted in Proteoliposomes

BACKGROUND: The entry of human immunodeficiency virus (HIV-1) into host cells involves the interaction of the viral exterior envelope glycoprotein, gp120, and receptors on the target cell. The HIV-1 receptors are CD4 and one of two chemokine receptors, CCR5 or CXCR4. METHODOLOGY/PRINCIPAL FINDINGS: We created proteoliposomes that contain CD4, the primary HIV-1 receptor, and one of the coreceptors, CXCR4. Antibodies against CD4 and CXCR4 specifically bound the proteoliposomes. CXCL12, the natural ligand for CXCR4, and the small-molecule CXCR4 antagonist, AMD3100, bound the proteoliposomes with affinities close to those associated with the binding of these molecules to cells expressing CXCR4 and CD4. The HIV-1 gp120 exterior envelope glycoprotein bound tightly to proteoliposomes expressing only CD4 and, in the presence of soluble CD4, bound weakly to proteoliposomes expressing only CXCR4. The thermal stability of CD4 and CXCR4 inserted into liposomes was examined. Thermal denaturation of CXCR4 followed second-order kinetics, with an activation energy (E(a)) of 269 kJ/mol (64.3 kcal/mol) and an inactivation temperature (T(i)) of 56°C. Thermal inactivation of CD4 exhibited a reaction order of 1.3, an E(a) of 278 kJ/mol (66.5 kcal/mol), and a T(i) of 52.2°C. The second-order denaturation kinetics of CXCR4 is unusual among G protein-coupled receptors, and may result from dimeric interactions between CXCR4 molecules. CONCLUSIONS/SIGNIFICANCE: Our studies with proteoliposomes containing the native HIV-1 receptors allowed an examination of the binding of biologically important ligands and revealed the higher-order denaturation kinetics of these receptors. CD4/CXCR4-proteoliposomes may be useful for the study of virus-target cell interactions and for the identification of inhibitors

Pengaruh Penggunaan Garam Rendah Natrium Pada Ikan Asin Tenggiri Papan (Scomberomorus Guttatus)

Masyarakat Kalimantan Selatan umumnya gemar makan ikan asin sejak dahulu kala. Di lain pihak, prevalensi hipertensi Kalimantan Selatan tertinggi di Indonesia (Kemenkes RI, 2018). Salah satu faktor resiko hipertensi adalah asupan natrium pada garam, hal ini berperan penting pada mekanisme timbulnya hipertensi. Produk ikan asin rendah natrium diharapkan dapat menjadi alternatif bagi masyarakat yang menyukai ikan asin dengan tetap mempertahankan tekanan darah dalam batasan normal. Permasalahan sekaligus tujuan yang dibahas pada penelitian ini adalah untuk mengetahui apakah ada pengaruh penggunaan garam rendah natrium (GRN) pada pengolahan ikan asin tenggiri papan terutama kadar protein, kadar natrium dan daya terima ikan asin tenggiri papan. Hasil penelitian menunjukkan bahwa kadar protein tertinggi ikan asin tenggiri papan adalah 17,98% (P3), dan terendah adalah 3,65% (P0). Hal ini menunjukkan bahwa semakin tinggi konsentrasi GRN yang diberikan, maka kadar protein yang dihasilkan produk ikan asin juga semakin tinggi. Kadar natrium ikan asin tenggiri papan yang tertinggi adalah 11,7% (P0), sedangkan yang terendah adalah 2,02% (P1). Hal ini menunjukkan bahwa perendaman ikan tenggiri papan pada GRN signifikan menurunkan kadar natrium pada produk ikan asin tenggiri papan namun makin tinggi konsentrasi GRN yang digunakan, kadar natrium yang dihasilkan produk ikan asin justru semakin tinggi. Dengan kata lain dapat dinyatakan bahwa jika ingin menghasilkan produk olahan pangan dengan kadar natrium rendah, penggunaan GRN signifikan berpengaruh namun dalam jumlah yang perlu dibatasi. Sementara dari hasil pengujian daya terima, rata-rata panelis menyukai P2 untuk karakter warna dan bau, P3 untuk karakter tekstur dan P1 untuk karakter rasa