A Genome-Wide Analysis of Genetic Diversity inTrypanosoma cruzi Intergenic Regions

Background Trypanosoma cruzi is the causal agent of Chagas Disease. Recently, the genomes of representative strains from two major evolutionary lineages were sequenced, allowing the construction of a detailed genetic diversity map for this important parasite. However this map is focused on coding regions of the genome, leaving a vast space of regulatory regions uncharacterized in terms of their evolutionary conservation and/or divergence. Methodology Using data from the hybrid CL Brener and Sylvio X10 genomes (from the TcVI and TcI Discrete Typing Units, respectively), we identified intergenic regions that share a common evolutionary ancestry, and are present in both CL Brener haplotypes (TcII-like and TcIII-like) and in the TcI genome; as well as intergenic regions that were conserved in only two of the three genomes/haplotypes analyzed. The genetic diversity in these regions was characterized in terms of the accumulation of indels and nucleotide changes. Principal Findings Based on this analysis we have identified i) a core of highly conserved intergenic regions, which remained essentially unchanged in independently evolving lineages; ii) intergenic regions that show high diversity in spite of still retaining their corresponding upstream and downstream coding sequences; iii) a number of defined sequence motifs that are shared by a number of unrelated intergenic regions. A fraction of indels explains the diversification of some intergenic regions by the expansion/contraction of microsatellite-like repeats.Fil: Panunzi, Leonardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Agüero, Fernan Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; Argentin

Consistency of compact and extended models of glucose-insulin homeostasis: The role of variable pancreatic reserve

Published compact and extended models of the glucose-insulin physiologic control system are compared, in order to understand why a specific functional form of the compact model proved to be necessary for a satisfactory representation of acute perturbation experiments such as the Intra Venous Glucose Tolerance Test (IVGTT). A spectrum of IVGTT’s of virtual subjects ranging from normal to IFG to IGT to frank T2DM were simulated using an extended model incorporating the population-of-controllers paradigm originally hypothesized by Grodsky, and proven to be able to capture a wide array of experimental results from heterogeneous perturbation procedures. The simulated IVGTT’s were then fitted with the Single-Delay Model (SDM), a compact model with only six free parameters, previously shown to be very effective in delivering precise estimates of insulin sensitivity and secretion during an IVGTT. Comparison of the generating, extended-model parameter values with the obtained compact model estimates shows that the functional form of the nonlinear insulin-secretion term, empirically found to be necessary for the compact model to satisfactorily fit clinical observations, captures the pancreatic reserve level of the simulated virtual patients. This result supports the validity of the compact model as a meaningful analysis tool for the clinical assessment of insulin sensitivity

Family Firms

We present a model of succession in a firm controlled and managed by its founder. The founder decides between hiring a professional manager or leaving management to his heir, as well as on how much, if any, of the shares to float on the stock exchange. We assume that a professional is a better manager than the heir, and describe how the founder’s decision is shaped by the legal environment. Specifically, we show that, in legal regimes that successfully limit the expropriation of minority shareholders, the widely held professionally managed corporation emerges as the equilibrium outcome. In legal regimes with intermediate protection, management is delegated to a professional, but the family stays on as large shareholders to monitor the manager. In legal regimes with the weakest protection, the founder designates his heir to manage and ownership remains inside the family. This theory of separation of ownership from management includes the Anglo-Saxon and the Continental European patterns of corporate governance as special cases, and generates additional empirical predictions consistent with crosscountry evidence.

Inheritance Law and Investment in Family Firms

Entrepreneurs may be constrained by the law to bequeath a minimal stake to non-controlling heirs. The size of this stake can reduce investment in family firms, by reducing the future income they can pledge to external financiers. Using a purpose-built indicator of the permissiveness of inheritance law and data for 10,245 firms from 32 countries over the 1990-2006 interval, we find that stricter inheritance law is associated with lower investment in family firms, while it leaves investment unaffected in non-family firms. Moreover, as predicted by the model, inheritance law affects investment only in family firms that experience a succession.Succession, Family Firms, Inheritance Law, Growth, Investment

Family Firms

We present a model of succession in a firm controlled and managed by its founder. The founder decides between hiring a professional manager or leaving management to his heir, as well as on how much, if any, of the shares to float on the stock exchange. We assume that a professional is a better manager than the heir, and describe how the founder's decision is shaped by the legal environment. Specifically, we show that, in legal regimes that successfully limit the expropriation of minority shareholders, the widely held professionally managed corporation emerges as the equilibrium outcome. In legal regimes with intermediate protection, management is delegated to a professional, but the family stays on as large shareholders to monitor the manager. In legal regimes with the weakest protection, the founder designates his heir to manage and ownership remains inside the family. This theory of separation of ownership from management includes the Anglo-Saxon and the Continental European patterns of corporate governance as special cases, and generates additional empirical predictions consistent with cross-country evidence.

Inheritance Law and Investment in Family Firms

Entrepreneurs may be constrained by the law to bequeath a minimal stake to non-controlling heirs. The size of this stake can reduce investment in family firms, by reducing the future income they can pledge to external financiers. Using a purpose-built indicator of the permissiveness of inheritance law and data for 10,245 firms from 32 countries over the 1990-2006 interval, we find that stricter inheritance law is associated with lower investment in family firms, while it leaves investment unaffected in non-family firms. Moreover, as predicted by the model, inheritance laws affects investment only in family firms that experience a succession.succession, family firms, inheritance law, growth, investment

A stochastic delay differential model of cerebral autoregulation

Mathematical models of the cardiovascular system and of cerebral autoregulation (CAR) have been employed for several years in order to describe the time course of pressures and flows changes subsequent to postural changes. The assessment of the degree of efficiency of cerebral auto regulation has indeed importance in the prognosis of such conditions as cerebro-vascular accidents or Alzheimer. In the quest for a simple but realistic mathematical description of cardiovascular control, which may be fitted onto non-invasive experimental observations after postural changes, the present work proposes a first version of an empirical Stochastic Delay Differential Equations (SDDEs) model. The model consists of a total of four SDDEs and two ancillary algebraic equations, incorporates four distinct delayed controls from the brain onto different components of the circulation, and is able to accurately capture the time course of mean arterial pressure and cerebral blood flow velocity signals, reproducing observed auto-correlated error around the expected drift

Novel solid-state emissive polymers and polymeric blends from a T-Shaped benzodifuran scaffold: A comparative study

Two novel polyimines were synthesized from a benzodifuran based diamino monomer and two dialdehydes bearing bulky groups and a flexible spacer. The polymers display tuned luminescence performance according to the presence of half-salen groups. The effect of the intramolecular bond on the emission properties were examined. Two model compounds, replicating the same emissive Schiff base cores, were synthetized. From the models, dye-doped blends in the fluorophore/matrix ratio, resembling the polymers, were produced. Amorphous thin films of the covalent polymers and the polymeric blends were obtained by spin-coating technique. The Photoluminescent (PL) response of the different macromolecular systems were qualitatively and quantitatively examined and compared

A novel DR/NIR T-shaped aiegen: Synthesis and x-ray crystal structure study

We developed a new benzodifuran derivative as the condensation product between 2,6-diamino-4-(4-nitrophenyl)benzo[1,2-b:4,5-b’]difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane π-stacked in a columnar arrangement

Agency conflicts, ownership concentration, and legal shareholder protection

This paper analyzes the interaction between legal shareholder protection, managerial incentives, monitoring, and ownership concentration. Legal protection affects the expropriation of shareholders and the blockholder's incentives to monitor. Because monitoring weakens managerial incentives, both effects jointly determine the relationship between legal protection and ownership concentration. When legal protection facilitates monitoring better laws strengthen the monitoring incentives, and ownership concentration and legal protection are inversely related. By contrast, when legal protection and monitoring are substitutes better laws weaken the monitoring incentives, and the relationship between legal protection and ownership concentration is non-monotone. This holds irrespective of whether or not the large shareholder can reap private benefits. Moreover, better legal protection may exacerbate rather than alleviate the conflict of interest between large and small shareholders