Biodiversidad del Parque Nacional Pre-Delta (Entre Ríos, Argentina). I) Riqueza del fitoplancton

Mirande, V., S. E. Haleblian, G. A. Barreto & B. C. Tracanna. 2009. Biodiversidad del Parque Nacional Pre-Delta (Entre Ríos, Argentina). I) Riqueza del fitoplancton. Lilloa 46 (1-2). El objetivo del presente trabajo fue contribuir al conocimiento de la riqueza del fitoplancton del Parque Nacional Pre-Delta. Hasta el presente se carece de un relevamiento ambiental y ficoflorístico de los cuerpos de agua de este parque, aunque sí se dispone de datos geomorfológicos, faunísticos y florísticos. Se seleccionaron siete sitios de muestreo correspondientes a ambientes lóticos y leníticos. Para la extracción de las muestras cualitativas se filtraron 32 litros de agua a través de una red de 20 µm de poro, las cuales fueron fijadas “in situ” con formaldehido al 4%. La comunidad estuvo compuesta por 102 especies pertenecientes a Cyanophyceae, Chlorophyceae, Charophyceae, Dinophyceae, Bacillariophyceae, Chrysophyceae, Xanthophyceae and Euglenophyceae, destacándose una mayor riqueza específica en las lagunas. Los resultados obtenidos evidenciaron a las diatomeas como el grupo que en líneas generales más contribuyó en especímenes. Se citan 26 especies y 3 variedades nuevas para el Noreste Argentino y, además de las mencionadas anteriormente, se aportan otras 18 especies y 6 variedades para la provincia de Entre Ríos. Todas las entidades comentadas son nuevos taxa para el área de estudio

Quantitative plane-resolved crystal growth and dissolution kinetics by coupling in situ optical microscopy and diffusion models : the case of salicylic acid in aqueous solution

The growth and dissolution kinetics of salicylic acid crystals are investigated in situ by focusing on individual microscale crystals. From a combination of optical microscopy and finite element method (FEM) modeling, it was possible to obtain a detailed quantitative picture of dissolution and growth dynamics for individual crystal faces. The approach uses real-time in situ growth and dissolution data (crystal size and shape as a function of time) to parametrize a FEM model incorporating surface kinetics and bulk to surface diffusion, from which concentration distributions and fluxes are obtained directly. It was found that the (001) face showed strong mass transport (diffusion) controlled behavior with an average surface concentration close to the solubility value during growth and dissolution over a wide range of bulk saturation levels. The (1̅10) and (110) faces exhibited mixed mass transport/surface controlled behavior, but with a strong diffusive component. As crystals became relatively large, they tended to exhibit peculiar hollow structures in the end (001) face, observed by interferometry and optical microscopy. Such features have been reported in a number of crystals, but there has not been a satisfactory explanation for their origin. The mass transport simulations indicate that there is a large difference in flux across the crystal surface, with high values at the edge of the (001) face compared to the center, and this flux has to be redistributed across the (001) surface. As the crystal grows, the redistribution process evidently can not be maintained so that the edges grow at the expense of the center, ultimately creating high index internal structures. At later times, we postulate that these high energy faces, starved of material from solution, dissolve and the extra flux of salicylic acid causes the voids to close

Composition of the Top Management Team and Firm International Diversification

This study investigates the impact of various top management team characteristics on firm international diversification. Relying on data from 126 firms in the electronics industry, we find that certain top management team characteristics are related to international expansion. Specifically, results indicate that lower average age, higher average tenure, higher average elite education, higher average international experience, and higher tenure heterogeneity are associated with firm international diversification. The study reinforces the importance of top management team composition in internationalization decisions and suggests further research in this context.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Risk propensity in the foreign direct investment location decision of emerging multinationals

A distinguishing feature of emerging economy multinationals is their apparent tolerance for host country institutional risk. Employing behavioral decision theory and quasi-experimental data, we find that managers’ domestic experience satisfaction increases their relative risk propensity regarding controllable risk (legally protectable loss), but decreases their tendency to accept non-controllable risk (e.g., political instability). In contrast, firms’ potential slack reduces relative risk propensity regarding controllable risk, yet amplifies the tendency to take non-controllable risk. We suggest that these counterbalancing effects might help explain observation that risk-taking in FDI location decisions is influenced by firm experience and context. The study provides a new understanding of why firms exhibit heterogeneous responses to host country risks, and the varying effects of institutions

Categorization of the main descriptors of different ampicillin crystal habits

With the purpose of enabling the analysis by digital methods of particles of multisource pharmaceutical raw materials, this study analyzed different crystal habits of ampicillin particles, by grouping the external shapes obtained from 3 different solvents (acetonitrile, ethanol, and methanol), thereby reducing the number of descriptors necessary to adequately represent each shape. For this purpose, a selection of morphological descriptors was used including: circularity, roughness, roundness, compactness, aspect ratio, effective diameter, solidity, convexity, fractal dimension, and 10 Complex Fourier descriptors. These measures cover highly diverse morphological properties and define the crystal habit of a particle. Principal Component Analysis (PCA) and the Cluster Analysis (CA) were the grouping techniques used, which demonstrated the possibility of using between 2 and 4 descriptors instead of the 18 proposed initially.Com o objetivo de possibilitar a análise, por meio de métodos digitais, de partículas de matérias-primas farmacêuticas de múltiplas fontes, analisaram-se diferentes cristais de partículas de ampicilina através do agrupamento de formas externas obtidas de três diferentes solventes (acetonitrila, etanol e metanol), reduzindo, desse modo, o número de descritores necessários para representar adequadamente cada forma. Com esse propósito, utilizou-se seleção de descritores morfológicos, incluindo: circularidade, aspereza, arredondamento, compactação, relação de aspecto, diâmetro efetivo, solidez, convectividade, dimensão fractal e 10 descritores complexos de Fourier. Essas medidas cobrem diversas propriedades morfológicas e definem a cristalinidade de uma partícula. As análises do componente principal (PCA) e por grupamento (CA) foram as técnicas de agrupamento utilizadas, que demonstraram a possibilidade de utilizar entre 2 e 4 descritores ao invés dos 18, inicialmente propostos

Learning Sequences: Their Existence, Effect, and Evolution

Much is known about the importance of learning and some of the distinct learning processes that organizations use (e.g., trial-and-error learning, vicarious learning, experimental learning, and improvisational learning). Yet surprisingly little is known about whether these processes combine over time in ordered ways, because most research on learning explores one particular process. Using theory elaboration and theory-building methods and data on the accumulated country entries of entrepreneurial firms, we address this gap. Our core contribution is an emergent theoretical framework that develops the concept of learning sequences. We find that learning sequences exist and are influenced by initial conditions. We also find that learning sequences evolve in fundamentally distinct ways over time and with repeated use. Finally, data show how different learning sequences differentially affect both shorter- and longer-term performance, suggesting that it matters which learning processes are used and when. Overall, our findings on learning sequences have important implications for learning theory, international entrepreneurship, and the growing literature on process management

The Stock Market Evaluation of IPO-Firm Takeovers

We conduct an event study to assess the stock market evaluation of public takeover announcements. Unlike the majority of previous research, we specifically focus on acquisitions targeted at newly public IPO-firms and show that the stock market positively evaluates these M&As as R&D. However, bidders' abnormal announcement returns are significantly lower for takeovers directed at targets with critical intangible assets and innovative capabilities inalienably bound to their initial owners than for those that have internally accumulated respective resources and capabilities. We explain these findings with the acquirer's post-acquisition dependence on continued access to the IPO-firm founders' target-specific human capital. Our results contribute to literature in that they show that the stock market perceives these potential impediments to successful exploitation of acquired strategic resources and thus identify a potential cause for heretofore mostly inconsistent evidence on bidder abnormal returns in corporate takeovers found in previous research

Corporate Governance and Its Impact on Firm Risk

The aim of this research is to explore the relationship of corporate governance with firm risk. This study establishes a link between corporate governance variables and firm risk for a sample of 106 Pakistani firms over a time of six years (2005-2010). Based on the estimation results, family control and bank control have negative impact on the firm risk whereas ownership structure and chairman/CEO duality posit positive relationship with risk. This provides a direction for firms to introduce more non-family control to the board of directors and not allow banks to have majority shareholding in their stocks. Also, directors should be asked to have a reasonable ownership in the stocks of the firm so that they can decide in the best interest of the firm and for the increase of their stock value. Chief executive should also hold the chair in order to have unity of command and a better decision-making influence