Validation of daily growth of African catfish Clarias gariepinus (Burchell 1822) young‐of‐the‐year from Lake Baringo,Kenya

The African catfish (Clarias gariepinus) is widely distributed in Africa, where it is a major food fish. The species comprises a significant component of commercial fishery landings in Kenya, and elsewhere in Africa. Nevertheless, little information or data exist on its age and growth characteristics, which is necessary for its sustainable management. This study determined this information from the microstructure of lapillar otoliths of the young‐of‐the‐year (YOY) of the species. Analysis of the otolith microstructure from fish of known age confirmed that one growth increment (circulus) was formed per day, forming the basis for their use to accurately age C. gariepinus YOY collected from Lake Baringo during the months of August and September 2007. The derived length–age relationship correlated significantly (Pearson Correlation, df = 53, P < 0.05), indicating that the YOY exhibited an average growth rate of 0.2285 cm day^?1. The largest specimen attained a total length of 40.5 cm in only 169 days. These results indicate that native C. gariepinus exhibits rapid growth, achieving a large size during the first year. Thus, they can be recommended for purposes of aquaculture.     

Autofrettage—Stress distribution under load and retained stresses after depressurization

There is a long-standing interest in developing a capability to predict the distribution of retained stresses in thick-walled tubes after the removal of an internal pressure—post-autofrettage. In this paper, four different methods of calculating such stresses are presented and compared. The methods presented are based on the following assumed yield criteria and deformation conditions: (1) Tresca's yield criterion, (2) Tresca's yield criterion × 2/√3, (3) Mises' yield criterion in plane-stress, and (4) Mises' yield criterion in plane-strain.     

Internal union dynamics during a strike: A quasi-experimental study.

Hypothesized that union members on strike will (a) give a higher evaluation of the union and of the leadership, (b) evaluate the benefit package more highly after the strike, (c) become more militant against the employer during the strike, (d) report more willingness to participate in union activities, and (e) show more intraunion cohesion during the strike. Random samples of members of 9 local unions (3 each from Ford, General Motors, and Chrysler) were surveyed on 4 occasions: before the 1976 bargaining, during the strike at Ford, after settlement of the national contract, and 7 mo after the strike ended. Usable responses from a questionnaire totaled 1,182 (405 strikers, 777 nonstrikers). With the exception of greater intraunion cohesion during the strike, all hypotheses were confirmed. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ARMA spectral estimation based on partial autocorrelations

This paper presents a new method for estimating the coefficients of autoregressive moving-average parameters of stationary time series. The method is based on computing the sample autocorrelations of the given time series and fitting an ARMA model so as to approximate the partial autocorrelations in a least-squares sense. When the given time series are characterized by spectral zeroes near the unit circle, they tend to have relatively long sequences of nonzero partial autocorrelations; hence the new method is especially effective in such cases. This paper contains a derivation of all necessary mathematical details, as well as several numerical examples illustrating the performance.     

Freeze concentration of milk and saline solutions in a liquid–solid fluidized bed: Part I. Experimental

Fluidized bed freeze concentration is a novel technique that uses a fluidized bed heat exchanger (FBHE) to concentrate liquids through the process of freeze concentration. Ice formed on the cooled surface of the vertical heat exchanger is removed by particles fluidized inside the FBHE. In this paper, the operating conditions are reported for freeze concentration of saline solutions and milk in FBHE. The operation was tested with equilateral 4 mm and then 5 mm particles at different bed porosities, cooling rates and NaCl and milk concentrations. Experiments with NaCl solutions showed that the 5 mm particles were more aggressive than 4 mm in removing ice from the heat exchanger wall. Whilst particle size was considered responsible for this, the particle shape could have played a major role. A theoretical analysis on effect of FBHE parameters showed the size of particles to exert influence on FBHE performance. The result from experiments with skim milk and whole milk maintained the conclusions formed previously with NaCl experiments with regard to the effect of tested parameters on operational stability. However, the ice formed from milk was more difficult to remove than the ice formed from NaCl solutions. Whole milk showed even more resistance to ice removal. Skim milk was freeze concentrated from 13% to 27% TS content in these experiments. Installing a wash screen further improved the purity of separated ice.     

Towards a Guideline for Design of a Corporate Entrepreneurship Function for Business Development in Medium‐Sized Technology‐Based Companies

The speed with which global high‐technology markets evolve makes companies recognize that an effective innovation process is the best way to guarantee competitiveness. However, when (medium‐sized) companies then wish to set up a corporate entrepreneurship function to enhance business development processes, they can find little material available in literature to assist in such processes. In this article we have described a guideline and some backgrounds for creating a corporate entrepreneurship function to realize business development in a high‐tech context.     

Characterizing the Influence of Water on Charging and Layering at Electrified Ionic‐Liquid/Solid Interfaces

The importance of water on molecular ion structuring and charging mechanism of solid interfaces in room temperature ionic liquid (RTIL) is unclear and has been largely ignored. Water may alter structures, charging characteristics, and hence performance at electrified solid/RTIL interfaces and is utilized in various fields including energy storage, conversion, or catalysis. Here, atomic force microscopy and surface forces apparatus experiments are utilized to directly measure how water alters the interfacial structuring and charging characteristics of [C₂mim][Tf₂N] on mica and electrified gold surfaces. On hydrophilic and ionophobic mica surfaces, water‐saturated [C₂mim][Tf₂N] dissolves surface‐bound cations, which leads to high surface charging and strong layering. In contrast, layering of dry RTIL at weakly charged mica surfaces is weakly structured. At electrified, hydrophobic, and ionophilic gold electrodes, significant water effects are found only at positive applied electrochemical potentials. Here, the influence of water is limited to interactions within the RTIL layers, and is not related to a direct electrosorption of water on the polarized electrode. More generally, the results suggest that effects of water on interfacial structuring of RTIL strongly depend on both (1) surface charging mechanism and (2) interfacial wetting properties. This may greatly impact utilization/design of RTILs and surfaces for interface‐dominated processes.