A TECHNICAL NOTE ON INPUT PRICE PROXIES USED IN SALMON FARMING INDUSTRY STUDIES

A frequently used data set on Norwegian fish farms has until recently not contained any data on feed price. Previous work has been based on a proxy variable approach that is not efficient. In this note, a more efficient approach is suggested. An ex post analysis, using data on feed price which is now available, is carried out to discriminate between alternative approaches.Demand and Price Analysis,

Micro foundations for knowledge spillovers in spatial equilibrium models

Knowledge spillovers have recently been analysed by Barde (2009) and Ostbye (2010) in a spatial general equilibrium framework. Both studies lack explicit micro foundations for the spillovers - spillovers just take place and depend on firm density. The models must therefore be seen as reduced forms that may potentially be consistent with several structural interpretations. In this paper, the aim is to go some way in offering plausible micro foundations. We consider two alternatives: knowledge dissemination through knowledge embodied in labour moving between firms following Combes and Duranton (2006) and knowledge creation and dissemination through research and development (R&D) following d'Asprémont and Jacquemin (1988)

Comparing home-grown fruits: productivity convergence across industries and regions

Output per worker is radically unevenly distributed across space. Several authors have asked why the differences are so large between countries and hypothesized that differences in social infrastructure provide an answer. However, differences in output per worker are also very different when comparing spatial units at lower levels of resolution without substantial variation in social infrastructure. The purpose of this paper is to discuss possible reasons why. We will do so by looking at regional data for the Scandinavian Peninsula at a spatial resolution equivalent to the European NUTS3. Since Norway and Sweden is considered particular egalitarian and homogeneous societies, differences in broad measures of social infrastructure can hardly be invoked as substantial important determinants of productive performance. Instead we suggest that differences in industrial structure and human capital are able to explain the differences we observe

Metode Nonlinear Least Square (NLS) Untuk Estimasi Parameter Model Wavelet Radial Basis Neural Network (WRBNN)

The use of wavelet radial basis model for forecasting nonlinear time series is introduced in this paper. The model is generated by artificial neural network approximation under restriction that the activation function on the hidden layers is radial basis. The current model is developed from the multiresolution autoregressives (MAR) model, with addition of radial basis function in the hidden layers. The power of model is compared to the other nonlinear model existed before, such as MAR model and Generalized Autoregressives Conditional Heteroscedastic (GARCH) model. The simulation data which be generated from GARCH process is applied to support the aim of research. The sufficiency of model is measured by sum squared of error (SSE). The computation results show that the proposed model has a power as good as GARCH model to carry on the heteroscedastic process

Dehydrogenation of propane by carbon supported metal catalysts

In this thesis, the catalytic properties of carbon supported Pt catalysts were investigated for the dehydrogenation of propane.Using a polyol process, Pt/Carbon catalysts active for propane dehydrogenation were successfully prepared using carbon black, graphite and a conical platelet CNF as supports.The catalysts were characterized using BET surface area measurements, TGA, volumetric and pulse hydrogen chemisorption and CO stripping voltammetry. The BET measurements found surface areas in the order carbon black > CNF > graphite with good measurement accuracy. The three subsequent methods were found impractical for the catalysts investigated due to poor measurement accuracy for the TGA compared to the size of the target value. The volumetric chemisorption was found unable to produce linear isotherms, likely caused by hydrogen-carbon interactions and the pulse experiment failed to find an optimal adsorption temperature that combined a managable rate of desorption with a high rate of adsorption. The CO stripping voltammetric experiment was found able to determine the dispersion of the carbon black and graphite supported catalysts and found the dispersion of Pt/Carbon black > graphite, with some uncertainty associated with the results.Experimental work was put into optimizing the catalyst activity measurement conditions and achieve an acceptable trade-off between pressure drop, deactivation rate and conversion levels. This was found at 500 C, 50 mL/min feed flow rate, 50 mg sample mass diluted with inerts and 0.5 %wt. Pt content in the catalysts. A kinetic study was performed and on a Pt/Carbon black catalyst, the propane dehydrogenation reaction was found to follow power law kinetics with a propane order of 0.9 and hydrogen order of −1.1. The accuracy of the measurements were better for the propane order than for hydrogen. The three different supports were compared for catalytic activity and it was found that the activity of Pt/Carbon black > graphite > CNF. The likely cause was the lower dispersion of the graphite supported catalyst compared to that of the carbon black supported catalyst. As the CNF supported catalyst was found less active than the graphite supported catalyst, it is likely that the CNF supported catalyst also had a low dispersion. The low dispersions is most likely caused by a combination of the low surface areas and the surface chemistries of the CNF and graphite supports

The Impact of Covariance Misspecification in Multivariate Gaussian Mixtures on Estimation and Inference: An Application to Longitudinal Modeling

Multivariate Gaussian mixtures are a class of models that provide a flexible parametric approach for the representation of heterogeneous multivariate outcomes. When the outcome is a vector of repeated measurements taken on the same subject, there is often inherent dependence between observations. However, a common covariance assumption is conditional independence---that is, given the mixture component label, the outcomes for subjects are independent. In this paper, we study, through asymptotic bias calculations and simulation, the impact of covariance misspecification in multivariate Gaussian mixtures. Although maximum likelihood estimators of regression and mixing probability parameters are not consistent under misspecification, they have little asymptotic bias when mixture components are well-separated or if the assumed correlation is close to the truth even when the covariance is misspecified. We also present a robust standard error estimator and show that it outperforms conventional estimators in simulations and can indicate the model is misspecified. Body mass index data from a national longitudinal study is used to demonstrate the effects of misspecification on potential inferences made in practice

Korišćenje in vitro model sistema za proučavanje osnovnih bioloških procesa kod riba

With the increasing replacement of fish meal and fish oil with new ingredients in aquaculture diets, imbalances in amino acids, fatty acids, vitamins and minerals can occur. The metabolic and regulatory processes underlying these nutrition-induced imbalances in fish are still not fully understood. At the cellular level, essential dietary compounds and micro-nutrients have been shown to influence lineage determination, differentiation and proliferation of certain cell types, and hence the development of tissue structures and organogenesis. An improved understanding of cellular and molecular events occurring during development in teleosts will enable us to better characterize and define particular requirements, customize feed components, and thus enable development of sustainable feeds, minimize the occurrence of disorders as well as maintain the continuous growth of the fish. In vitro techniques have a great potential in experiments involving mechanism based hypothesis testing, where there is a significant need for a complete understanding of basic biological processes. Cell cultures provide means to study single-factor effects and the combinations thereof in detail, and further, to investigate the role of particular nutrients and their specific gene interactions, which are not possible when working at the organism level. In addition, whole organisms are complex and vary individually, depending on age, sex, health status, type of meal, genetics etc., which makes it difficult to accurately simulate nutritional processes. In vitro experiments offer the unique opportunity to develop standardized methods to study quality of novel and fortified feed products by studying the cellular and molecular effect of different types of food products, ranging from proteins to n-3 fatty acids (FAs) and from fat-soluble vitamins to minerals and trace elements. The system may also be used for studies on the development of functional feeds such as probiotics, prebiotics, bioactive peptides, lipase inhibitors, fat and cholesterol binders and antioxidants. Results from selected in vitro trials, showing how different nutrients may influence development of fat, bone and muscle cells and lipid metabolism in liver cells, will be presented.Zamena ribljeg brašna i ulja sa novim, alternativnim izvorima proteina i masti u hrani za ribe može dovesti do narušavanja odnosa amino kiselina, masnih kiselina i minerala kod ovih organizama. Promene u metaboličkim i regulatornim procesima koje mogu da nastanu loše balansiranom ishranom još uvek nisu dobro proučene kod riba. Esencijalne hranljive materije i mikronutrijenti mogu da utiču na razvoj pojedinih ćelijskih linija, njihovu proliferaciju, a samim tim i na pravilan razvoj tkiva i organa. Bolje razumevanje ćelijskih i molekularnih procesa, koji se dešavaju tokom razvića košljoriba će nam omogućiti da bolje razumemo i definišemo određene zahteve za ishranom na svakom stupnju razvoja riba, prilagodimo komponente riblje hrane, a samim tim i omogućimo normalan razvoj i rast riba, kao i da sprečimo pojavu različitih poremećaja. Korišćenje in vitro sistema predstavlja veliki potencijal za testiranje novih komponenata hrane i daje nam mogućnost za razumevanje osnovnih bioloških procesa kod riba. Prednost korišćenja ćelijskih kultura je što nam one omogućavaju da proučavamo uticaj pojedinačnih faktora, ali i kombinaciju dva ili više različitih faktora i njihov uticaj na gene, što nije moguće istraživati na nivou organizma. Pored toga proučavanje organizma kao celine je jako složeno, jer zavisi od pola, zdravstvenog stanja jedinke, ishrane, genetike, itd., te je na ovaj način lakše simulirati procese ishrane. In vitro eksperimenti nude jedinstvenu priliku da razvijemo standardizovane metode za proučavanje kvaliteta i efekata novih hranljivih materija: od proteina, preko masnih kiselina i minerala, do elemenata, koji se u hrani nalaze u tragovima. Ovi sistemi mogu se koristiti i za proučavanje novih, funkcionalnih hraniva, kao što su: probiotici, prebiotici, bioaktivni peptidi, masti, inhibitori lipaze, antioksidansi. Biće prikazani rezultati odabranih in vitro ispitivanja uticaja različitih hraniva na metabolizam masnog tkiva, kostiju i mišića kao i na sam metabolizam masti