6,283 research outputs found
Are SMEs large firms en miniature? Evidence from a growth analysis
Based on German data between 1999 and 2007, we analyze the growth factors of SMEs and contrast them with those of large _rms. Differences show up both in balance sheet and employment growth. While we confirm earlier results on inherent growth structures and the influence of firm age, we derive several new, complex growth effects that set SMEs apart: particularly ownership type and ownership structure play a distinctive role that may additionally interact with other variables affecting growth, such as, e.g. profitability or capital structure. As such, the distinction - according to size - between SMEs and large firms may not be sufficiently meaningful unless combined with further information on ownership type and structure and, preferably, also on firm age. --Small and medium-sized enterprises,growth analysis,panel analysis,system GMM estimation
Convective instability and mass transport of diffusion layers in a Hele-Shaw geometry
We consider experimentally the instability and mass transport of a
porous-medium flow in a Hele-Shaw geometry. In an initially stable
configuration, a lighter fluid (water) is located over a heavier fluid
(propylene glycol). The fluids mix via diffusion with some regions of the
resulting mixture being heavier than either pure fluid. Density-driven
convection occurs with downward penetrating dense fingers that transport mass
much more effectively than diffusion alone. We investigate the initial
instability and the quasi steady state. The convective time and velocity
scales, finger width, wave number selection, and normalized mass transport are
determined for 6,000<Ra<90,000. The results have important implications for
determining the time scales and rates of dissolution trapping of carbon dioxide
in brine aquifers proposed as possible geologic repositories for sequestering
carbon dioxide.Comment: 4 page, 3 figure
A Study of the Variation of the Fluoride Content of Certain Waters in the Vicinity of Albuquerque
In the first part of 1935, the City of Albuquerque was investigating the possibility of obtaining an additional water supply from the Jemez Mountains, which are about fifty miles to the north of the City. Black and Veatch, consulting engineers for the City, were asked to make a complete study of the problem. The question of fluorides in the water came up because it was known that the fluorides would cause mottled enamel in human teeth when the water was used during childhood, if the content was above 0.9 parts per million by accepted fluorine analysis methods. The question arose as to how the fluoride content of the Jemez stream would vary over a period of months, and how it would vary as the stream progresses along Its course
Part I: Synthesis and Chemistry of 2-Aryl-2-Nitroacetates Part II: Development of Anion-Binding Catalysts Part III: Analysis of an Axial Chiral Tetrachlorinated Bisbenzo[a]phenazine
PART I. There are few reports on the synthesis of 2-aryl-2-nitroacetates, highlighting a need for development in this area. This section describes a high-throughput experimentation (HTE) approach to discover suitable conditions for the coupling of aryl bromides and α-nitroacetates to generate 2-aryl-2-nitroacetates. The best reaction conditions are 2.5 mol % Pd2dba3•CHCl3, 10 mol % t-BuXPhos, 1.2 equiv CsHCO3 in toluene at 75 °C, which afford products in isolated yields of 52–96%.
2-Aryl-2-nitroacetates are central precursors to other small molecules making them valuable building blocks in synthesis. Efficient methods were developed for the conversion of 2-aryl-2-nitroacetates to several product classes that are difficult to make: aryl nitromethanes (76–98% yield), α-keto esters (51–86% yield), and α-aryl α-amino acids (63–85% yield).
PART II. Small molecule organocatalytic anion-binding chemistry is in its early stages of development in the organic laboratory, and research in this field is important for its advancement. This section describes synthesis of a new class of anion-binding catalysts focused on a xanthene scaffold.
Over twenty potential catalysts were made and include three types: unsymmetrical catalysts, C2-symmetrical catalysts, and bifunctional catalysts. These compounds are better at promoting the Pictet-Spengler-type reaction previously reported by Jacobsen. Because of this fact the cyclization of 3- and 2-substituted furans into N-acyliminium ions was investigated. The top catalyst for 2-substituted furans is a bisamide xanthene compound (60% conversion), and the top catalyst for 3-substituted furans is a thiourea-amide xanthene compound (42% conversion, 24% ee).
PART III. The discovery of new materials is an exciting and important field of organic synthesis. A tetrachlorinated bisbenzo[a]phenazine was accessed in seven steps and 14% overall yield (99% ee). It has unique chromic properties that justify its application in functional materials. The color-changing transitions and the corresponding solid phases were studied using single crystal x-ray diffraction, powder x-ray diffraction, photo-image processing, and differential scanning calorimetry. These properties arise from two polymorphs and the ability of the phenazine to form weak OH•••Cl interactions
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The Architecture of Children's Physics Knowledge a Problem-Solving Perspective
The project investigated the nature of young children's physics knowledge and the architecture of its development. I utilized two contexts of development for this purpose: comparison of cross-age developments in knowledge of a domain and finegrained analysis of developments that occurred in the context of problem-resolution.The empirical base consisted of three conditions, under which preschoolers were asked to establish equilibrium on the pan balance. Analysis focused on the child's transformation of a number-based to a weight-based approach to the problem. All the conditions employed the same nine sets of elements to be balanced; the conditions varied a) whether or not the child received feedback from the apparatus and b) order of set presentation (total n= 56). A sequence of fine-grained analyses of the videotaped data lead to a view of children's physics knowledge as localized and context-sensitive;with the steps involved in its development as remarkably limited in extension : in a) the scope within which they come to represent weight or weight differences (e.g. discrete elements versus collective weight of elements in a pan) b) the scope of contexts in which they come to view weight as relevant to the goal of mechanical equilibrium and c) the bounds of diagnostic and causal implication
Human Trafficking in Mongolia
DOI: 10.5564/mjia.v0i13.12Mongolian Journal of International Affairs No.13 2006 pp.95-10
Private and public information in self-fulfilling currency crises
This paper analyzes the implications of currency crises in a model with unique equilibrium. Starting from a typical multiple equilibria model with self-fulfilling expectations we introduce noisy information, following Morris/Shin (1999). Under certain conditions for the noise parameter, all equilibria but one are eliminated so that we are able to derive comparative statics and subsequent policy devices. We can show that if the a priori expected fundamental state of the economy is good, there is an incentive for the government to disseminate very precise information. However, a high precision of public information increases the danger of an attack if ex-ante expected fundamentals are bad. Moreover, we find that the influence of private information's precision is exactly the reverse. --Currency Crises,Common Knowledge,Multiple Equilibria
Benthic communities of the Weddell Sea : Past, present and future
The present thesis tackles different aspects of the past, present and future of high Antarctic benthic communities of the Weddell Sea. It first compares methodological approaches to sample benthos, showing the complementarity of two quantitative techniques. Then reviews knowledge on bentho-pelagic coupling on Antarctic shelves, showing that bentho-pelagic coupling differs considerably based on local characteristics. This methodological and conceptual knowledge is uses to study the benthic communities in the hard to access Filchner Region (southern Weddell Sea), describing two novel communities, and shows the influence of environmental drivers over benthic distribution. The final topic is the temporal dynamics of benthos. For this, a long-term study which considers a unique 26-year time series of benthic data from the southeastern Weddell Sea is used. Here, benthic communities appear severely affected by a decrease of productivity, and increase of scouring potential, especially after the year 2000
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