Cost of and returns from bangos production by size of farm and type of climate

This is a discussion of the production costs, yields, and profitability of different sizes of fish farming operations, and of fish farms operating under different types of Philippine climate

Intrinsically disordered inhibitor of glutamine synthetase is a functional protein with random-coil-like pKa values

The sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT) in cyanobacteria allows the incorporation of ammonium into carbon skeletons. In the cyanobacterium Synechocystis sp. PCC 6803, the activity of GS is modulated by the interaction with proteins, which include a 65-residue-long intrinsically disordered protein (IDP), the inactivating factor IF7. This interaction is regulated by the presence of charged residues in both IF7 and GS. To understand how charged amino acids can affect the binding of an IDP with its target and to provide clues on electrostatic interactions in disordered states of proteins, we measured the pKa values of all IF7 acidic groups (Glu32, Glu36, Glu38, Asp40, Asp58, and Ser65, the backbone C-terminus) at 100 mM NaCl concentration, by using NMR spectroscopy. We also obtained solution structures of IF7 through molecular dynamics simulation, validated them on the basis of previous experiments, and used them to obtain theoretical estimates of the pKa values. Titration values for the two Asp and three Glu residues of IF7 were similar to those reported for random-coil models, suggesting the lack of electrostatic interactions around these residues. Furthermore, our results suggest the presence of helical structure at the N-terminus of the protein and of conformational changes at acidic pH values. The overall experimental and in silico findings suggest that local interactions and conformational equilibria do not play a role in determining the electrostatic features of the acidic residues of IF7.Ministerio de Economía y Competitividad CTQ 2015-64445-R, BFU2013- 41712-P, BIO2016-75634PJunta de Andalucía BIO-284Generalitat Valenciana Prometeo 018/201

Do Institutions Cause Growth?

We revisit the debate over whether political institutions cause economic growth, or whether, alternatively, growth and human capital accumulation lead to institutional improvement. We find that most indicators of institutional quality used to establish the proposition that institutions cause growth are constructed to be conceptually unsuitable for that purpose. We also find that some of the instrumental variable techniques used in the literature are flawed. Basic OLS results, as well as a variety of additional evidence, suggest that a) human capital is a more basic source of growth than are the institutions, b) poor countries get out of poverty through good policies, often pursued by dictators, and c) subsequently improve their political institutions.

The New Comparative Economics

In recent years, comparative economics experienced a revival, with a new focus on comparing capitalist economies. The theme of the new research is that institutions exert a profound influence on economic development. We argue that, to understand capitalist institutions, one needs to understand the basic tradeoff between the costs of disorder and those of dictatorship. We then apply this logic to study the structure of efficient institutions, the consequences of colonial transplantation, and the politics of institutional choice.

The New Comparative Economics

In recent years, comparative economics experienced a revival, with a new focus on comparing capitalist economies. The theme of the new research is that institutions exert a profound influence on economic development. We argue that, to understand capitalist institutions, one needs to understand the basic tradeoff between the costs of disorder and those of dictatorship. We then apply this logic to study the structure of efficient institutions, the consequences of colonial transplantation, and the politics of institutional choice.

The Stokes-Einstein Relation at Moderate Schmidt Number

The Stokes-Einstein relation for the self-diffusion coefficient of a spherical particle suspended in an incompressible fluid is an asymptotic result in the limit of large Schmidt number, that is, when momentum diffuses much faster than the particle. When the Schmidt number is moderate, which happens in most particle methods for hydrodynamics, deviations from the Stokes-Einstein prediction are expected. We study these corrections computationally using a recently-developed minimally-resolved method for coupling particles to an incompressible fluctuating fluid in both two and three dimensions. We find that for moderate Schmidt numbers the diffusion coefficient is reduced relative to the Stokes-Einstein prediction by an amount inversely proportional to the Schmidt number in both two and three dimensions. We find, however, that the Einstein formula is obeyed at all Schmidt numbers, consistent with linear response theory. The numerical data is in good agreement with an approximate self-consistent theory, which can be used to estimate finite-Schmidt number corrections in a variety of methods. Our results indicate that the corrections to the Stokes-Einstein formula come primarily from the fact that the particle itself diffuses together with the momentum. Our study separates effects coming from corrections to no-slip hydrodynamics from those of finite separation of time scales, allowing for a better understanding of widely observed deviations from the Stokes-Einstein prediction in particle methods such as molecular dynamics.Comment: Submitte

The fate of methanol in anaerobic bioreactors

Methanol is an important component of certain industrial wastewaters. In anaerobic environments, methanol can be utilized by methanogens and acetogens. In wastewater treatment plants, the conversion of methanol into methane is preferred because this conversion is responsible for chemical oxygen demand (COD) removal, whereas with the formation of volatile fatty acids (VFA) little COD removal is achieved. Moreover, the accumulation of VFA can lead to reactor instability due to pH drops, in weakly buffered systems. The undesirable formation of VFA has previously been associated with the presence of trace elements and bicarbonate in the medium.This thesis investigates the environmental factors that lead to the predominance of acetogens over methanogens during anaerobic wastetewater treatment of methanol. For this purpose, batch and continuous experiment were carried out using a model medium composed of methanol and defined mineral nutrients. The main factors studied were: the effect of trace elements, the reactor pH, the bicarbonate level, and the methanol concentration in the reactor.In Chapter 1 an introductory review is given about anaerobic methylotrophic metabolism in environmental biotechnology. The natural and anthropogenic sources of methanol and other methylated compounds are outlined. In addition, the anaerobic methylotophic microorganisms and the biochemistry of methanol metabolism in methanogens and acetogens are briefly described. Finally, the previous experience in environmental biotechnology with the anaerobic biodegradation of methylotrophic substrates is reviewed. Included is a summary of the reactor types, efficiencies achieved and organic loadings applied for the treatment of wastewaters containing methanol.In Chapter 2, the effect of trace elements on the anaerobic conversion of methanol was studied. Cobalt was the only trace element tested which greatly enhanced methanogenesis from methanol. In continuous experiments, less acetate was formed in a cobalt-deprived reactor than in a cobalt supplemented reactor. These results suggested that cobalt levels could be used to prevent acetate formation from methanol. Therefore, in Chapter 3 the effect of cobalt addition for each individual trophic group was evaluated. Using specific inhibitors, specific activity and the kinetic parameters, μmax and Ks, were determined. Methylotrophic methanogens and acetogens were the only trophic group stimulated by cobalt addition, while the other trophic groups utilizing downstream intermediates, H 2 /CO 2 or acetate, were largely unaffected. At a low cobalt concentration, both methylotrophs had similar growth rates, whereas at high cobalt levels, acetogens grew slightly faster. The optimal cobalt concentration for both methylotrophic populations was around 0.05 mg · l -1.In Chapter 4, the possibility of the anaerobic treatment of methanol without addition of any alkalinity was investigated. Methanol can successfully be converted into methane, regardless of the low pH value of alkalinity-free medium. An astonishing high specific methanogenic activity of 3.57 g COD · g -1VSS · d -1was evident, which enable the conversion of 13 g COD · l -1· d -1to methane during continuous operation at a reactor pH 4.2. A Methanosarcina- like organism was the main methanogen responsible for the conversion of methanol to methane.Chapter 5 presents the effect of inorganic carbon, alkalinity addition and reactor methanol concentration in anaerobic reactors. The results indicated that acetogenesis occurred only when exogenous bicarbonate was added, when unionized VFA accumulated and in the presence of high methanol concentrations, confirming the previously determined 60 times higher substrate affinity of methanogens.The results of this dissertation are summarized in Chapter 6. Methylotrophic methanogens will predominate over a broad pH range (4.2 to 7.2) if either the reactor methanol concentration, inorganic carbon content, or the cobalt concentration is low. Significant acetogenesis can only be expected to predominate if the reactor methanol concentration is high (>1000 mg COD · l -1), exogenous inorganic carbon is supplied, cobalt is available and methanogens are inhibited, e.g. by undissociated VFA. All these four conditions have to be met. Addition of moderate levels of NaHCO 3 (approximately 10-20 meq · l -1) were found to create such conditions if the reactor was overloaded

Aplicación de algoritmos genéticos a la identificación de la estructura de enlaces en portales web

Este trabajo explora la estructura de enlaces de los portales web considerándolos como grafos interconectados y analizando sus características como una red social. A partir de cada dominio raíz se extraerán dos redes: la primera, una red de dominios y la segunda, una red de páginas accesibles desde el dominio raíz. Sobre ambas redes se evaluarán una serie de parámetros desde la perspectiva del análisis de redes sociales para caracterizar la estructura del portal. El análisis factorial proporciona la metodología estadística adecuada para extraer los principales perfiles de portales web a partir de sus características como grafo. No obstante, y debido al gran número de indicadores que se pueden obtener, la búsqueda exploratoria de los factores latentes implicaría contemplar un número de posibilidades extremadamente elevado que imposibilitaría la obtención de una solución óptima. Por ello, en este trabajo se propone la utilización de una búsqueda genética sobre el conjunto de indicadores de partida. Los algoritmos genéticos son capaces de proporcionar un subconjunto de indicadores que optimizan una función objetivo. Los resultados obtenidos categorizan los portales webs corporativos en cuanto a su estructura de enlaces y destacan las posibilidades de los algoritmos genéticos como herramienta para descubrir nuevo conocimiento

Web site structure mining using social network analysis

Purpose – Web sites are typically designed attending to a variety of criteria. However, web site structure determines browsing behavior and way-finding results. The aim of this study is to identify the main profiles of web sites’ organizational structure by modeling them as graphs and considering several social network analysis features. Design/methodology/approach – A case study based on 80 institutional Spanish universities’ web sites has been used for this purpose. For each root domain, two different networks have been considered: the first is the domain network, and the second is the page network. In both cases, several indicators related to social network analysis have been evaluated to characterize the web site structure. Factor analysis provides the statistical methodology to adequately extract the main web site profiles in terms of their internal structure. Findings – This paper allows the categorization of web site design styles and provides general guidelines to assist designers to better identify areas for creating and improving institutional web sites. The findings of this study offer practical implications to web site designers for creating and maintaining an effective web presence, and for improving usability. Research limitations/implications – The research is limited to 80 institutional Spanish universities’ web sites. Other institutional university web sites from different countries can be analyzed, and the conclusions could be compared or enlarged. Originality/value – This paper highlights the importance of the internal web sites structure, and their implications on usability and way-finding results. As a difference to previous research, the paper is focused on the comparison of internal structure of institutional web sites, rather than analyzing the web as a whole or the interrelations among web sitesMinisterio de Educación y Ciencia DPI2007- 60128Junta de Andalucía. Consejería de Innovación, Ciencia y Empresa P07-TIC-0262

An evolutionary factor analysis computation for mining website structures

This paper explores website link structure considering websites as interconnected graphs and analyzing their features as a social network. Two networks have been extracted for representing websites: a domain network containing subdomains or external domains linked through the website and a page network containing webpages browsed from the root domain. Factor analysis provides the statistical methodology to adequately extract the main website profiles in terms of their internal structure. However, due to the large number of indicators, the task of selecting a representative subset of indicators becomes unaffordable. A genetic search of an optimum subset of indicators is proposed in this paper, selecting a multiobjective fitness function based on factor analysis results. The optimum solution provides a coherent and relevant categorization of website profiles, and highlights the possibilities of genetic algorithms as a tool for discovering new knowledge in the field of web miningMinisterio de Educación y Ciencia DPI2007- 60128Junta de Andalucía. Consejería de Innovación, Ciencia y Empresa P07-TIC-0262