Anàlisi del projecte d’innovació en l’àrea de matemàtiques a la comunitat educativa Creciendo juntos: Parque Paso del Rey, Moreno, Argentina

Resum de les pràctiques desenvolupades l’estiu de 2007 a l’escola Creciendo Juntos, situada a Parque Paso del Rey de Moreno, una ciutat de la perifèria de Buenos Aires, Argentina. Es basa principalment en l’anàlisi d’un projecte d’innovació en l’àrea de matemàtiques què realitzava l’escola

Optical-geometrical effects on the photoluminescence spectra of Si nanocrystals embedded in SiO2

We demonstrate that thickness, optical constants, and details of the multilayer stack, together with the detection setting, strongly influence the photoluminescence spectra of Si nanocrystals embedded in SiO2. Due to multiple reflections of the visible light against the opaque silicon substrate, an interference pattern is built inside the oxide layer, which is responsible for the modifications in the measured spectra. This interference effect is complicated by the depth dependence of (i) the intensity of the excitation laser and (ii) the concentration of the emitting nanocrystals. These variations can give rise to apparent features in the recorded spectra, such as peak shifts, satellite shoulders, and even splittings, which can be mistaken as intrinsic material features. Thus, they can give rise to an erroneous attribution of optical bands or estimate of the average particle size, while they are only optical-geometrical artifacts. We have analyzed these effects as a function of material composition (Si excess fraction) and thickness, and also evaluated how the geometry of the detection setup affects the measurements. To correct the experimental photoluminescence spectra and extract the true spectral shape of the emission from Si nanocrystals, we have developed an algorithm based on a modulation function, which depends on both the multilayer sequence and the experimental configuration. This procedure can be easily extended to other heterogeneous systems.

Identification by Real-time PCR of 13 mature microRNAs differentially expressed in colorectal cancer and non-tumoral tissues

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. In our study, we examined by Real-Time PCR the expression of 156 mature miRNA in colorectal cancer. The analysis by several bioinformatics algorithms of colorectal tumours and adjacent non-neoplastic tissues from patients and colorectal cancer cell lines allowed identifying a group of 13 miRNA whose expression is significantly altered in this tumor. The most significantly deregulated miRNA being miR-31, miR-96, miR-133b, miR-135b, miR-145, and miR-183. In addition, the expression level of miR-31 was correlated with the stage of CRC tumor. Our results suggest that miRNA expression profile could have relevance to the biological and clinical behavior of colorectal neoplasia.

Pint lincRNA connects the p53 pathway with epigenetic silencing by the Polycomb repressive complex 2

BACKGROUND: The p53 transcription factor is located at the core of a complex wiring of signaling pathways that are critical for the preservation of cellular homeostasis. Only recently it has become clear that p53 regulates the expression of several long intergenic noncoding RNAs (lincRNAs). However, relatively little is known about the role that lincRNAs play in this pathway. RESULTS: Here we characterize a lincRNA named Pint (p53 induced noncoding transcript). We show that Pint is a ubiquitously expressed lincRNA that is finely regulated by p53. In mouse cells, Pint promotes cell proliferation and survival by regulating the expression of genes of the TGF-β, MAPK and p53 pathways. Pint is a nuclear lincRNA that directly interacts with the Polycomb repressive complex 2 (PRC2), and is required for PRC2 targeting of specific genes for H3K27 tri-methylation and repression. Furthermore, Pint functional activity is highly dependent on PRC2 expression. We have also identified Pint human ortholog (PINT), which presents suggestive analogies with the murine lincRNA. PINT is similarly regulated by p53, and its expression significantly correlates with the same cellular pathways as the mouse ortholog, including the p53 pathway. Interestingly, PINT is downregulated in colon primary tumors, while its overexpression inhibits the proliferation of tumor cells, suggesting a possible role as tumor suppressor. CONCLUSIONS: Our results reveal a p53 autoregulatory negative mechanism where a lincRNA connects p53 activation with epigenetic silencing by PRC2. Additionally, we show analogies and differences between the murine and human orthologs, identifying a novel tumor suppressor candidate lincRNA.

Pint lincRNA connects the p53 pathway with epigenetic silencing by the Polycomb repressive complex 2

BACKGROUND: The p53 transcription factor is located at the core of a complex wiring of signaling pathways that are critical for the preservation of cellular homeostasis. Only recently it has become clear that p53 regulates the expression of several long intergenic noncoding RNAs (lincRNAs). However, relatively little is known about the role that lincRNAs play in this pathway. RESULTS: Here we characterize a lincRNA named Pint (p53 induced noncoding transcript). We show that Pint is a ubiquitously expressed lincRNA that is finely regulated by p53. In mouse cells, Pint promotes cell proliferation and survival by regulating the expression of genes of the TGF-β, MAPK and p53 pathways. Pint is a nuclear lincRNA that directly interacts with the Polycomb repressive complex 2 (PRC2), and is required for PRC2 targeting of specific genes for H3K27 tri-methylation and repression. Furthermore, Pint functional activity is highly dependent on PRC2 expression. We have also identified Pint human ortholog (PINT), which presents suggestive analogies with the murine lincRNA. PINT is similarly regulated by p53, and its expression significantly correlates with the same cellular pathways as the mouse ortholog, including the p53 pathway. Interestingly, PINT is downregulated in colon primary tumors, while its overexpression inhibits the proliferation of tumor cells, suggesting a possible role as tumor suppressor. CONCLUSIONS: Our results reveal a p53 autoregulatory negative mechanism where a lincRNA connects p53 activation with epigenetic silencing by PRC2. Additionally, we show analogies and differences between the murine and human orthologs, identifying a novel tumor suppressor candidate lincRNA.

Ilustración y nihilismo en los Artículos de Mariano José de Larra

En la primera parte de este artículo se muestra cómo el concepto de ser humano que Larra utiliza en sus escritos es de clara raigambre ilustrada. En la segunda, se analiza cómo el autor de los Artículos, tras tomar conciencia de los límites de dicho ideal, reaccionó con un extremismo nihilista que le llevó a ver como detestables aquellas capacidades humanas que los ilustrados habían valorado positivamente: el lenguaje, la racionalidad y la sociabilidad. En la tercera parte, se estudia, a la luz de los escritos de Friedrich Nietzsche, los dos tipos de nihilismo que se enfrentaron en el espíritu y en la obra de Larra.

Factor decomposition of spatial income inequality: a revision

Duro and Esteban (1998) proposed an additive decomposition of Theil populationweighted index by four income multiplicative factors (in spatial contexts). This note makes some additional methodological points: first, it argues that interaction effects are taken into account in the factoral indexes although only in a fairly restrictive way. As a consequence, we suggest to rewrite the decomposition formula as a sum of strict Theil indexes plus the interactive terms; second, it might be instructive to aggregate some of the initial factors; third, this decomposition can be immediately extended to the between- and within-group components.

Análisis de agrupaciones provinciales a partir del enfoque de desigualdad y polarización: una nota

Con motivo de analizar las fuentes de las desigualdades interprovinciales de la renta en España las provincias vienen siendo agrupadas en función de su pertenencia a las CCAA. Este criterio de tipificación, de origen administrativo, no agota, sin embargo, las posibilidades existentes en orden a dividir a las provincias en grupos pretendidamente homogéneos. Disponemos, por ejemplo, de agrupaciones informales como las NUTS 1 europeas, los ejes de desarrollo (VILLAVERDE Y PÉREZ (1996) y las áreas geoeconómicas (ALCAIDE (2002) ó formales, como las sugeridas por AGHEVLI y MEHRAN (1981) y DAVIES y SHORROCKS (1989). El principal objeto de esta nota consiste en evaluar el atractivo asociado a esta variedad de agregaciones atendiendo a dos criterios básicos: el error de agregación y el número de grupos considerado.

Polarització comarcal de rendes a Catalunya

Sovint parlem de les comarques catalanes en termes de grups més o menys homogenis. Per exemple, les segmenten en riques i pobres, en dinàmiques i estancades, en interiors o costaneres, etc. Apart de l'interès com a instrument de síntesi, el grau de formació de grups cohesionats i distants entre si pot ser un assumpte rellevant en termes de la cohesió territorial. En aquestes circumstàncies, la disponibilitat d'una mesura específica que permeti la quantificació precisa d'aquest fenomen sembla particularment útil. En aquest sentit, la literatura ens ha suggerit diverses mesures de polarització, entre les que s’haurien de destacar els Índexos de Polarització Generalitzada (Esteban, Gradín i Ray (1999)). El principal objecte d'aquest treball consisteix a aplicar aquestes mesures a la distribució comarcal de la renda a Catalunya al llarg del període 1990-2002. El principal resultat obtingut apunta cap a una creixent polarització econòmica de les comarques que, conjuntament amb l'increment observat en les desigualtats, recolzaria una actitud molt més decidida per part de l'administració en el reequilibri del territori.

Regional income inequalities in Europe: an updated measurement and some decomposition results

In this paper well-known summary inequality indexes are used to explore interregional income inequalities in Europe. In particular, we mainly employ Theils’population-weighted index because of its appealing properties. Two decomposition analysis are applied. First, regional inequalities are decomposed by regional subgroups (countries). Second, intertemporal inequality changes are separated into income and population changes. The main results can be summarized as follows. First, data confirm a reduction in crossregional inequality during 1982-97. Second, this reduction is basically due to real convergence among countries. Third, currently the greater part of European interregional disparities is within-country by nature, which introduce an important challenge for the European policy. Fourth, inequality changes are due mainly to income variations, population changes playing a minor role.

Análisis de los factores determinantes de las desigualdades internacionales en las emisiones de CO2 per cápita aplicando el enfoque distributivo: una metodología de descomposición por factores de Kaya

En este trabajo desarrollamos una metodología para descomponer las desigualdades internacionales en las emisiones de CO2 en factores (multiplicativos) de Kaya y dos términos de interacción. Utilizamos el índice de desigualdad de Theil y mostramos que esta metodología de descomposición puede extenderse para analizar los componentes de desigualdad inter e intragrupal. A continuación podemos analizar los factores detrás de las desigualdades en las emisiones de CO2 per cápita entre países, entre grupos de países y dentro de los grupos de países. La ilustración empírica sugiere algunas cuestiones. Primero, la desigualdad internacional en las emisiones de CO2 per cápita es principalmente atribuible a las desigualdades en los niveles de renta per cápita, lo que ayuda a explicar su reciente reducción, mientras que las diferencias en la intensidad de carbono de la energía y la intensidad energética han hecho una contribución mucho menos significativa. Este resultado está fuertemente influenciado por el comportamiento de China e India. En segundo lugar, el componente de la desigualdad entre grupos, que es el mayor, está también explicado en buena medida por el factor ingreso. En tercer lugar, el componente de la desigualdad dentro de los grupos aumentó ligeramente durante el período, algo principalmente debido al cambio en el factor de ingreso y los términos de interacción en unas pocas regiones.

Planta de producción de carbonato sódico

Aquest projecte presenta el procés de producció del carbonat sòdic a partir del mètode Solvay. Aquest procés es caracteritza perquè a partir de matèries primes molt bàsiques, com són el clorur sòdic i la pedra caliça, s'obté un producte de gran mercat, el carbonat sòdic. En el projecte s'estudien tant el disseny dels equips que seràn part del procès de producció com els sistemes de control utilitzats, impactes mediambientals que es puguin generar o l'avaluació econòmica de l'acceptació del procés en el mercat, entre d'altres.

Estudi urbanístic de Vilassar de Mar

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2006. S’analitza la situació urbanística actual de Vilassar de Mar i es proposen nous equipaments centrant-se sobre tot en un projecte de mercat municipal. L’anàlisi inclou la identificació de la problemàtica del municipi, el plantejament d’un nou model de poble cap al que hauria de tendir, la definició de les actuacions escaients per al canvi de la vila i, finalment, una proposta per la construcció d'un nou mercat municipal a la vila de Vilassar de Mar.

Cooperative vs. non-cooperative mechanisms in the EU decision making process

According to the account of the European Union (EU) decision making proposed in this paper, this is a bargaining process during which actors shift their policy positions with a view to reaching agreements on controversial issues.