FORMULATION OF THE HEAT CONDUCTION EQUATION FOR HETEROGENEOUS MEDIA WITH MULTIPLE SPATIAL SCALES USING REITERATED HOMOGENIZATION

Heterogeneous media with multiple spatial scales are finding increased importance in engineering. An example might be a large scale, otherwise homogeneous medium filled with dispersed small-scale particles that form aggregate structures at an intermediate scale. The objective in this paper is to formulate the strong-form Fourier heat conduction equation for such media using the method of reiterated homogenization. The phases are assumed to have a perfect thermal contact at the interface. The ratio of two successive length scales of the medium is a constant small parameter ε. The method is an up-scaling procedure that writes the temperature field as an asymptotic multiple-scale expansion in powers of the small parameter ε . The technique leads to two pairs of local and homogenized equations, linked by effective coefficients. In this manner the medium behavior at the smallest scales is seen to affect the macroscale behavior, which is the main interest in engineering. To facilitate the physical understanding of the formulation, an analytical solution is obtained for the heat conduction equation in a functionally graded material (FGM). The approach presented here may serve as a basis for future efforts to numerically compute effective properties of heterogeneous media with multiple spatial scales

Decrypting the Mitochondrial Gene Pool of Modern Panamanians

The Isthmus of Panama–the narrow neck of land connecting the northern and southern American landmasses–was an obligatory corridor for the Paleo-Indians as they moved into South America. Archaeological evidence suggests an unbroken link between modern natives and their Paleo-Indian ancestors in some areas of Panama, even if the surviving indigenous groups account for only 12.3% of the total population. To evaluate if modern Panamanians have retained a larger fraction of the native pre-Columbian gene pool in their maternally-inherited mitochondrial genome, DNA samples and historical records were collected from more than 1500 volunteer participants living in the nine provinces and four indigenous territories of the Republic. Due to recent gene-flow, we detected ∼14% African mitochondrial lineages, confirming the demographic impact of the Atlantic slave trade and subsequent African immigration into Panama from Caribbean islands, and a small European (∼2%) component, indicating only a minor influence of colonialism on the maternal side. The majority (∼83%) of Panamanian mtDNAs clustered into native pan-American lineages, mostly represented by haplogroup A2 (51%). These findings reveal an overwhelming native maternal legacy in today's Panama, which is in contrast with the overall concept of personal identity shared by many Panamanians. Moreover, the A2 sub-clades A2ad and A2af (with the previously named 6 bp Huetar deletion), when analyzed at the maximum level of resolution (26 entire mitochondrial genomes), confirm the major role of the Pacific coastal path in the peopling of North, Central and South America, and testify to the antiquity of native mitochondrial genomes in Panama

EWS/ETS Regulates the Expression of the Dickkopf Family in Ewing Family Tumor Cells

BACKGROUND: The Dickkopf (DKK) family comprises a set of proteins that function as regulators of Wnt/beta-catenin signaling and has a crucial role in development. Recent studies have revealed the involvement of this family in tumorigenesis, however their role in tumorigenesis is still remained unclear. METHODOLOGY/PRINCIPAL FINDINGS: We found increased expression of DKK2 but decreased expression of DKK1 in Ewing family tumor (EFT) cells. We showed that EFT-specific EWS/ETS fusion proteins enhance the DKK2 promoter activity, but not DKK1 promoter activity, via ets binding sites (EBSs) in the 5' upstream region. EWS/ETS-mediated transactivation of the promoter was suppressed by the deletion and mutation of EBSs located upstream of the DKK2 gene. Interestingly, the inducible expression of EWS/ETS resulted in the strong induction of DKK2 expression and inhibition of DKK1 expression in human primary mesenchymal progenitor cells that are thought to be a candidate of cell origin of EFT. In addition, using an EFT cell line SK-ES1 cells, we also demonstrated that the expression of DKK1 and DKK2 is mutually exclusive, and the ectopic expression of DKK1, but not DKK2, resulted in the suppression of tumor growth in immuno-deficient mice. CONCLUSIONS/SIGNIFICANCE: Our results suggested that DKK2 could not functionally substitute for DKK1 tumor-suppressive effect in EFT. Given the mutually exclusive expression of DKK1 and DKK2, EWS/ETS regulates the transcription of the DKK family, and the EWS/ETS-mediated DKK2 up-regulation could affect the tumorigenicity of EFT in an indirect manner

New World Civitas, Contested Jurisdictions and Intercultural Conversation in the Construction of the Spanish Monarchy

Jurisdictional frontiers were created, contested, and negotiated among a wide range of actors, including native Americans and Europeans, with reference to the cities founded in Castilla del Oro (roughly present-day Panama). This research deals, first, with the reshaping of the concept of a city in the New World, based on its inhabitants' sense of civitas. It analyses, secondly, the creation and redefinition of jurisdiction during political conflicts and, third, the construction and maintenance of jurisdiction through local relations with indigenous populations described as "conversation". The analysis of the creation and preservation of local jurisdictions allows for an interpretation of the complexities involved in the configuration of political power and political space from below in the territories claimed by the Spanish Monarchy.Art Empir

Arpías y Cocuyos

Dos textos de un libro al que tentativamente la autora tituló como "Reunión de zooliloquios". El primero es un poema en homenaje a Louise Nevelson

La adolescente embarazada: actitud y conducta de la adolescente y del progenitor ante su rol de padres y cómo son percibidos por sus familias

Incluye BibliografíaTeniendo como base empírica una muestra de 500 madres adolescentes, solteras, cuyos hijos cumplían en 1987 entre 2 y 5 años (p.27), el estudio se orienta a describir y analizar las actitudes y conductas de la adolescente y del progenitor frente a su papel de padres, cómo se perciben a si mismos y cómo son percibidos por sus familias