Garnet growth in the Nufenen Pass area (Swiss Alps)

Abstract : Textural division of a mineral in pyramids, with their apices located at the centre of the mineral and their bases corresponding to the mineral faces is called textural sector zoning. Textural sector zoning is observed in many metamorphic minerals like andalousite and garnet. Garnets found in the graphite rich black shales of the Mesozoic cover of the Gotthard Massif display textural sector zoning. The morphology of this sector zoning is not the same in different types of black shales observed in the Nufenen pass area. Garnets in foliated black shales display a well developed sector zoning while garnets found in cm-scale layered black shales display well developed sectors in the direction of the schistosity plane. This sector zoning is always associated with up to 30μm sized birefringent lamellae emanating radial from the sector boundaries. They alternate with isotrope lamellae. The garnet forming reaction was determined using singular value decomposition approach and results compared to thermodynamic calculations. It is of the form chl + mu + cc + cld = bt + fds + ank + gt + czo and is similar in both layered and foliated black shales. The calculated X(O) is close to 0.36 and does not significantly vary during the metamorphic history of the rock. This corresponds to X CO2, X CH4, and X H2O BSE imaging of garnets on oriented-cuts revealed that the orientation of the lamellae found within the sectors is controlled by crystallography. BSE imaging and electron microprobe analysis revealed that these lamellae are calcium rich compared to the isotropic lamellae. The addition of Ca to an almandine rich garnet causes a small distortion of the X site and potentially, ordering. Ordered and disordered garnet might have very similar free energies for this composition. Hence, two garnets with different composition can be precipitated with minor overstepping of the reaction. It is enough that continued nucleation of a new garnet layer slightly prefers the same structure to assure a fiber-like growth of both garnet compositions side by side. This hypothesis is in agreement with the thermodynamic properties of the garnet solid solution described in the literature and could explain the textures observed in garnets with these compositions. To understand the differences in sector zoning morphology, and crystal growth kinetics, crystal size distribution were determined in several samples using 2D spatial analysis of slab surfaces. The same nucleation rate law was chosen for all cases. Different growth rate law for non-layered black shales and layered black shales were used. Garnet in layered black shales grew according to a growth rate law of the form R=kt ½. The transport of nutrient is the limiting factor. Transport will occur preferentially on the schistosity planes. The shapes of the garnets in such rocks are therefore ovoid with the longest axis parallel to the schistosity planes. Sector zoning is less developed with sectors present only parallel to the schistosity planes. Garnet in non-layered blackshales grew according to a growth rate law of the form R=kt. The limiting factor is the attachment at the surface of the garnet. Garnets in these rocks will display a well developed sector zoning in all directions. The growth rate law is thus influenced by the texture of the rock. It favours or hinders the transport of nutrient to the mineral surface. Résumé : La zonation sectorielle texturale consiste en la division d'un cristal en pyramides dont les sommets sont localisés au centre du minéral. La base de ces pyramides correspond aux faces du minéral. Ce type de zonation est fréquemment observé dans les minéraux métamorphiques tels que l'andalousite ou le grenat. Les grenats présents dans les marnes riches en graphites de la couverture Mésozoïque du Massif du Gotthard présent une zonation sectorielle texturale. La morphologie de cette zonation n'est pas la même dans les marnes litées et dans les marnes foliées. Les grenats des marnes foliées montrent des secteurs bien développés dans 3 directions. Les grenats des marnes litées montrent des secteurs développés uniquement dans la direction des plans de schistosité. Cette zonation sectorielle est toujours associée à des lamelles biréfringentes de quelques microns de large qui partent de la limite des secteurs et qui sont perpendiculaires aux faces du grenat. Ces lamelles alternent avec des lamelles isotropes. La réaction de formation du grenat a été déterminée par calcul matriciel et thermodynamique. La réaction est de la forme chl + mu + cc + cld= bt + fds + ank + gt + czo. Elle est similaire dans les roches litées et dans les roches foliées. L'évaluation des conditions fluides montrent que le X(O) est proche de 0.36 et ne change pas de façon significative durant l'histoire métamorphique de la roche. Des images BSE sur des coupes orientées ont révélé que l'orientation de lamelles biréfringentes est contrôlée parla crystallographie. La comparaison des analyses à la microsonde électronique et des images BSE révèle également que les lamelles biréfringentes sont plus riches en calcium que les lamelles isotropes. L'addition de calcium va déformer légèrement le site X et ainsi créer un ordre sur ce site. L'énergie interne d'un grenat ordré et d'un grenat désordonné sont suffisamment proches pour qu'un léger dépassement de l'énergie de la réaction de formation permette la coexistence des 2 types de grenat dans le même minéral. La formation de lamelles est expliquée par le fait qu'un grenat préférera la même structure. Ces observations sont en accord avec la thermodynamique des solutions solides du grenat et permet d'expliquer les structures similaires observées dans des grenats provenant de lithologies différentes. Une étude de la distribution des tailles des grenats et une modélisation de la croissance a permis de mettre en évidence 2 mécanismes de croissance différents suivant la texture de la roche. Dans les 2 cas, la loi de nucléation est la même. Dans les roches litées, la loi de croissance est de forme R=kt½. Le transport des nutriments est le facteur limitant. Ce transport a lieu préférentiellement dans la direction des niveaux de schistosité. Les grenats ont une forme légèrement allongée car la croissance des secteurs est facilitée sur les niveaux de schistosité. La croissance des grenats dans les roches foliées suit une loi de croissance de la forme R=kt. Les seuls facteurs limitant la croissance sont les processus d'attachement à la surface du grenat. La loi de croissance de ces grenats est donc contrainte par la texture de la roche. Cela se marque par des différences dans la morphologie de la zonation sectorielle.

PHYTOCHROME KINASE SUBSTRATE4 modulates phytochrome-mediated control of hypocotyl growth orientation

Gravity and light are major factors shaping plant growth. Light perceived by phytochromes leads to seedling deetiolation, which includes the deviation from vertical hypocotyl growth and promotes hypocotyl phototropism. These light responses enhance survival of young seedlings during their emergence from the soil. The PHYTOCHROME KINASE SUBSTRATE (PKS) family is composed of four members in Arabidopsis (Arabidopsis thaliana): PKS1 to PKS4. Here we show that PKS4 is a negative regulator of both phytochrome A- and B-mediated inhibition of hypocotyl growth and promotion of cotyledon unfolding. Most prominently, pks4 mutants show abnormal phytochrome-modulated hypocotyl growth orientation. In dark-grown seedlings hypocotyls change from the original orientation defined by seed position to the upright orientation defined by gravity and light reduces the magnitude of this shift. In older seedlings with the hypocotyls already oriented by gravity, light promotes the deviation from vertical orientation. Based on the characterization of pks4 mutants we propose that PKS4 inhibits changes in growth orientation under red or far-red light. Our data suggest that in these light conditions PKS4 acts as an inhibitor of asymmetric growth. This hypothesis is supported by the phenotype of PKS4 overexpressers. Together with previous findings, these results indicate that the PKS family plays important functions during light-regulated tropic growth responses

Study of a population of Biomphalaria tenagophila (Orbigny, 1835) and of schistosomiasis transmission in "Alto da Boa Vista", Rio de Janeiro

The present study was performed using data from a Biomphalaria tenagophila population located in a water cress garden in the Alto da Boa Vista region representing an isolated focal point of schistosomiasis in the city of Rio de Janeiro. The density and age structure of this B. tenagophila population and its rate of intection by Schistosoma mansoni were studied for a period of 15 months. The snail population showed seasonal variation in density, with a decrease in number of individual at the begining of the rainy season. At the end of this season, the population consisted mainly of adults (92.8% in May 1985 and 82.8% in April 1986). The population growth curve was logistic and of sigmoidal configuration. Shiscotoma mansoni cercariae were eliminated over a short period of time (March, April and May 1986). The release of cercariae of S. mansoni and of birds seems to depend on environmental temperature, which during certain months would show a daily variation of up to 13ºC, with the lower thermal limit approaching the limit value for sporocyte development.

Tax Structure, Growth and Welfare in the UK

This paper studies the quantitative implications of changes in the composition of taxes for long-run growth and expected lifetime utility in the UK economy over 1970-2005. Our setup is a dynamic stochastic general equilibrium model incorporating a detailed scal policy struc- ture, and where the engine of endogenous growth is human capital accumulation. The government s spending instruments include pub- lic consumption, investment and education spending. On the revenue side, labour, capital and consumption taxes are employed. Our results suggest that if the goal of tax policy is to promote long-run growth by altering relative tax rates, then it should reduce labour taxes while simultaneously increasing capital or consumption taxes to make up for the loss in labour tax revenue. In contrast, a welfare promoting policy would be to cut capital taxes, while concurrently increasing labour or consumption taxes to make up for the loss in capital tax revenue.

Firms in Scottish High Technology Clusters: software, life sciences, microelectronics, optoelectronics and digital media – preliminary evidence and analysis on firm size, growth and optimality

This paper reports on: (a) new primary source evidence on; and (b) statistical and econometric analysis of high technology clusters in Scotland. It focuses on the following sectors: software, life sciences, microelectronics, optoelectronics, and digital media. Evidence on a postal and e-mailed questionnaire is presented and discussed under the headings of: performance, resources, collaboration & cooperation, embeddedness, and innovation. The sampled firms are characterised as being small (viz. micro-firms and SMEs), knowledge intensive (largely graduate staff), research intensive (mean spend on R&D GBP 842k), and internationalised (mainly selling to markets beyond Europe). Preliminary statistical evidence is presented on Gibrat’s Law (independence of growth and size) and the Schumpeterian Hypothesis (scale economies in R&D). Estimates suggest a short-run equilibrium size of just 100 employees, but a long-run equilibrium size of 1000 employees. Further, to achieve the Schumpeterian effect (of marked scale economies in R&D), estimates suggest that firms have to grow to very much larger sizes of beyond 3,000 employees. We argue that the principal way of achieving the latter scale may need to be by takeovers and mergers, rather than by internally driven growth.

Solovian and New Growth Theory from the Perspective of Allyn Young on Macroeconomic Increasing Returns

This paper evaluates, from an Allyn Youngian perspective, the neoclassical Solow model of growth and the associated empirical estimates of the sources of growth based on it. It attempts to clarify Young’s particular concept of generalised or macroeconomic “increasing returns” to show the limitations of a model of growth based on an assumption that the aggregate production function is characterised by constant returns to scale but “augmented” by exogenous technical progress. Young’s concept of endogenous, self-sustaining growth is also shown to differ in important respects (including in its policy implications) from modern endogenous growth theory.

Entrepreneurial Orientation, Intangible Assets and Firm Growth: the impact of ‘Spirit and Material’ on the growth of Chinese private firms

This paper has three contributions. First, it shows how field work within small firms in PR Chinese has provided new evidence which enables us to measure and calibrate Entrepreneurial Orientation (EO), as ‘spirit’, and Intangible Assets (IA), as ‘material’, for use in models of small firm growth. Second, it uses inter-item correlation analysis and both exploratory and confirmatory factor analysis to provide new measures of EO and IA, in index and in vector form, for use in econometric models of firm growth. Third, it estimates two new econometric models of small firm employment growth in PR China, under the null hypothesis of Gibrat’s Law, using our two new index-based and vector-based measures of EO and IA. Estimation is by OLS with adjustment for heteroscedasticity, and for sample selectivity. Broadly, it finds that EO attributes have had little significant impact on small firm growth, and indeed innovativeness and pro-activity paradoxically may even dampen growth. However, IA attributes have had a positive and significant impact on growth, with networking, and technological knowledge being of prime importance, and intellectual property and human capital being of lesser but still significant importance. In the light of these results, Gibrat’s Law is generalized, and Jovanovic’s learning theory is extended, to emphasise the importance of IA to growth. These findings cast new empirical light on the oft-quoted national slogan in PR China of “spirit and material”. So far as small firms are concerned, this paper suggests that their contribution to PR China’s remarkable economic growth is not so much attributable to the ‘spirit’ of enterprise (as suggested by propaganda) as, more prosaically, to the pursuit of the ‘material’.

Growth and Survival Determinants of Chinese Private Firms: Fieldwork evidence and econometric estimates

This paper reports on one of the first empirical attempts to investigate small firm growth and survival, and their determinants, in the Peoples’ Republic of China. The work is based on field work evidence gathered from a sample of 83 Chinese private firms (mainly SMEs) collected initially by face-to-face interviews, and subsequently by follow-up telephone interviews a year later. We extend the models of Gibrat (1931) and Jovanovic (1982), which traditionally focus on size and age alone (e.g. Brock and Evans, 1986), to a ‘comprehensive’ growth model with two types of additional explanatory variables: firm-specific (e.g. business planning); and environmental (e.g. choice of location). We estimate two econometric models: a ‘basic’ age-size-growth model; and a ‘comprehensive’ growth model, using Heckman’s two-step regression procedure. Estimation is by log-linear regression on cross-section data, with corrections for sample selection bias and heteroskedasticity. Our results refute a pure Gibrat model (but support a more general variant) and support the learning model, as regards the consequences of size and age for growth; and our extension to a comprehensive model highlights the importance of location choice and customer orientation for the growth of Chinese private firms. In the latter model, growth is explained by variables like planning, R&D orientation, market competition, elasticity of demand etc. as well as by control variables. Our work on small firm growth achieves two things. First, it upholds the validity of ‘basic’ size-age-growth models, and successfully applies them to the Chinese economy. Second, it extends the compass of such models to a ‘comprehensive’ growth model incorporating firm-specific and environmental variables.

A Panel Data Investigation of Real Exchange Rate Misalignment and Growth

The paper investigates the role of real exchange rate misalignment on long-run growth for a set of ninety countries using time series data from 1980 to 2004. We first estimate a panel data model (using fixed and random effects) for the real exchange rate, with different model specifications, in order to produce estimates of the equilibrium real exchange rate and this is then used to construct measures of real exchange rate misalignment. We also provide an alternative set of estimates of real exchange rate misalignment using panel cointegration methods. The variables used in our real exchange rate models are: real per capita GDP; net foreign assets; terms of trade and government consumption. The results for the two-step System GMM panel growth models indicate that the coefficients for real exchange rate misalignment are positive for different model specification and samples, which means that a more depreciated (appreciated) real exchange rate helps (harms) long-run growth. The estimated coefficients are higher for developing and emerging countries.

Phosphorylated MAP1b, alias MAP5 and MAP1x, is involved in axonal growth and neuronal mitosis.

Microtubule-associated protein 1b, also named MAP5 and MAP1x, is essential for neuronal differentiation. In kitten cerebellum, this protein is partially phosphorylated. During early postnatal development, a phosphorylated form was localized prominently in growing parallel fibres and in mitotic spindles of neuroblasts in the germinal layer, whereas a non-phosphorylated MAP1b form was found in dendrites, perikarya and axons. The MAP1x epitope showed the same immunohistochemical distribution, as seen for phosphorylated MAP1b, while its recognition on immunoblots was independent of phosphorylation. It is concluded that post-translational modifications and conformation of MAP1b influence the immunological detection of MAP1b, and are essential in the neuronal growth processes and mitosis. The antibody against the phosphorylated MAP1b may represent a good marker to identify dividing neurones.

The Role of Institutions in Cross-Section Income and Panel Data Growth Models: A Deeper Investigation on the Weakness and Proliferation of Instruments

This paper investigates the role of institutions in determining per capita income levels and growth. It contributes to the empirical literature by using different variables as proxies for institutions and by developing a deeper analysis of the issues arising from the use of weak and too many instruments in per capita income and growth regressions. The cross-section estimation suggests that institutions seem to matter, regardless if they are the only explanatory variable or are combined with geographical and integration variables, although most models suffer from the issue of weak instruments. The results from the growth models provides some interesting results: there is mixed evidence on the role of institutions and such evidence is more likely to be associated with law and order and investment profile; government spending is an important policy variable; collapsing the number of instruments results in fewer significant coefficients for institutions.

Finance and Balanced Growth

The Uzawa (1961) theorem applied to finance and growthsuggests that a long-run positive correlation between financial efficiency and depth is only present when variations in the extent of access to financial services are considered. Improvements in financial efficiency can lead to new capital augmenting technologies along the balanced path, but only improvements in financial efficiency directed towards labor can change the rate of growth in the long-run. These findings suggest ways to understand some of the more nuanced relationships between finance and growth observed in the data and point in a number of directions for future research.

Evaluating sampling strategies and logistic regression methods for modelling complex land cover changes

The role of land cover change as a significant component of global change has become increasingly recognized in recent decades. Large databases measuring land cover change, and the data which can potentially be used to explain the observed changes, are also becoming more commonly available. When developing statistical models to investigate observed changes, it is important to be aware that the chosen sampling strategy and modelling techniques can influence results. We present a comparison of three sampling strategies and two forms of grouped logistic regression models (multinomial and ordinal) in the investigation of patterns of successional change after agricultural land abandonment in Switzerland. Results indicated that both ordinal and nominal transitional change occurs in the landscape and that the use of different sampling regimes and modelling techniques as investigative tools yield different results. Synthesis and applications. Our multimodel inference identified successfully a set of consistently selected indicators of land cover change, which can be used to predict further change, including annual average temperature, the number of already overgrown neighbouring areas of land and distance to historically destructive avalanche sites. This allows for more reliable decision making and planning with respect to landscape management. Although both model approaches gave similar results, ordinal regression yielded more parsimonious models that identified the important predictors of land cover change more efficiently. Thus, this approach is favourable where land cover change pattern can be interpreted as an ordinal process. Otherwise, multinomial logistic regression is a viable alternative.

Growth Rate Estimation in the presence of Unit Roots

This study addresses the issue of the presence of a unit root on the growth rate estimation by the least-squares approach. We argue that when the log of a variable contains a unit root, i.e., it is not stationary then the growth rate estimate from the log-linear trend model is not a valid representation of the actual growth of the series. In fact, under such a situation, we show that the growth of the series is the cumulative impact of a stochastic process. As such the growth estimate from such a model is just a spurious representation of the actual growth of the series, which we refer to as a “pseudo growth rate”. Hence such an estimate should be interpreted with caution. On the other hand, we highlight that the statistical representation of a series as containing a unit root is not easy to separate from an alternative description which represents the series as fundamentally deterministic (no unit root) but containing a structural break. In search of a way around this, our study presents a survey of both the theoretical and empirical literature on unit root tests that takes into account possible structural breaks. We show that when a series is trendstationary with breaks, it is possible to use the log-linear trend model to obtain well defined estimates of growth rates for sub-periods which are valid representations of the actual growth of the series. Finally, to highlight the above issues, we carry out an empirical application whereby we estimate meaningful growth rates of real wages per worker for 51 industries from the organised manufacturing sector in India for the period 1973-2003, which are not only unbiased but also asymptotically efficient. We use these growth rate estimates to highlight the evolving inter-industry wage structure in India.

Negative investment in China: financing constraints and restructuring versus growth

This paper attempts to address a puzzle in China’s investment pattern: despite high aggregate investment and remarkable economic growth, negative net investment is commonly found at the microeconomic level. Using a large firm-level dataset, we test three hypotheses to explain the existence and extent of negative investment in each ownership group: what we term the efficiency (or restructuring) hypothesis, the (lack of) financing hypothesis, and the (slow) growth hypothesis. Our panel data probit estimations shows that negative investment by state-owned firms can be explained mainly by inefficiency: owing to over-investment or mis-investment in the past, these firms have had to restructure and to get rid of obsolete capital in the face of increasing competition and hardening budgets. The financing explanation holds for private firms, which have had to divest in order to raise capital. However, rapid economic growth weighs against both effects in all types of firms, with a larger impact for firms in the private and foreign sectors. A tobit model, estimated to examine the determinants of the amount of negative investment, yields similar conclusions.