Anaerobic fermentation of xylose by pichia stipitis: The effect of forced cycling of ph

Xylose fermentation by Pichia stipitis was examined using a two-stage batch process. The cells were first grown aerobically on D-xylose (5 g/L), whereafter additional xylose (10 g/L) was added and fermented during anaerobic conditions (T=30°C). The optimum pH value for a fermentation with constant pH was found to be 4.5 (maximum specific ethanol production rate 0.21 g/(g h). Forced square wave cycling of the pH between 4 and 5, and 3.5 and 5.5 (cycle time 30 min) during the fermentation stage resulted in a fermentation rate lower than the maximum rate, but with unchanged ethanol yields.     

An Empirical Study on Views of Importance of Change Impact Analysis Issues

Change impact analysis is a change management activity that previously has been studied much from a technical perspective. For example, much work focuses on methods for determining the impact of a change. In this paper, we present results from a study on the role of impact analysis in the change management process. In the study, impact analysis issues were prioritised with respect to criticality by software professionals from an organisational perspective and a self-perspective. The software professionals belonged to three organisational levels: operative, tactical and strategic. Qualitative and statistical analyses with respect to differences between perspectives as well as levels are presented. The results show that important issues for a particular level are tightly related to how the level is defined. Similarly, issues important from an organisational perspective are more holistic than those important from a self-perspective. However, our data indicate that the self-perspective colours the organisational perspective, meaning that personal opinions and attitudes cannot easily be disregarded. In comparing the perspectives and the levels, we visualise the differences in a way that allow us to discuss two classes of issues: high-priority and medium-priority. The most important issues from this point of view concern fundamental aspects of impact analysis and its execution.     

Industry evaluation of the Requirements Abstraction Model

Software requirements are often formulated on different levels and hence they are difficult to compare to each other. To address this issue, a model that allows for placing requirements on different levels has been developed. The model supports both abstraction and refinement of requirements, and hence requirements can both be compared with each other and to product strategies. Comparison between requirements will allow for prioritization of requirements, which in many cases is impossible if the requirements are described on different abstraction levels. Comparison to product strategies will enable early and systematic acceptance or dismissal of requirements, minimizing the risk for overloading. This paper presents an industrial evaluation of the model. It has been evaluated in two different companies, and the experiences and findings are presented. It is concluded that the requirements abstraction model provides helpful improvements to the industrial requirements engineering process.

Hyaluronan Synthase and Hyaluronidase Expression in Serous Ovarian Carcinoma is Related to Anatomic Site and Chemotherapy Exposure

The present study investigated the expression and clinical role of hyaluronan synthases (HAS1-3) and hyaluronidases (Hyal1-3) in serous ovarian carcinoma. HAS and HYAL mRNA expression was analyzed in 97 tumors (61 effusions, 27 primary carcinomas, 9 solid metastases) using PCR and further studied for association with clinicopathologic parameters, including survival. HAS1 mRNA was overexpressed in effusions compared to primary carcinomas and solid metastases (p < 0.001), and an alternatively spliced HAS1 was expressed only in effusions. HAS2 mRNA was overexpressed in solid metastases and primary carcinomas compared to effusions (p = 0.043), and HAS3 mRNA was overexpressed in primary carcinomas and effusions compared to solid metastases (p = 0.008). HYAL1 mRNA was absent in all specimens, whereas HYAL2 was expressed as two splice variants, of which HYAL2-var2 was overexpressed in solid metastases compared to effusions and primary carcinomas (p < 0.001). HYAL3 mRNA was expressed as wild-type and variant 1–3 form, the latter more highly in primary carcinomas and effusions compared to solid metastases (p = 0.006). HAS1 mRNA was overexpressed in pre- compared to post-chemotherapy effusions (p < 0.001), with opposite finding for HYAL2-var1 and HYAL3-WT (p = 0.016 and p = 0.024, respectively). Higher HYAL2-var1 and HAS1 splice variant mRNA expression in effusions was associated with longer (p = 0.033) and shorter (p = 0.047) overall survival, respectively. These data are the first to document a role for HAS and Hyal members in tumor progression in ovarian carcinoma, as evidenced by their differential expression as function of anatomic site and chemotherapy exposure, with a possible prognostic role for patients with malignant effusions.     

Prediction of fracture healing under axial loading,shear loading and bending is possible using distortional and dilatational strains as determining mechanical stimuli

Numerical models of secondary fracture healing are based on mechanoregulatory algorithms that use distortional strain alone or in combination with either dilatational strain or fluid velocity as determining stimuli for tissue differentiation and development. Comparison of these algorithms has previously suggested that healing processes under torsional rotational loading can only be properly simulated by considering fluid velocity and deviatoric strain as the regulatory stimuli. We hypothesize that sufficient calibration on uncertain input parameters will enhance our existing model, which uses distortional and dilatational strains as determining stimuli, to properly simulate fracture healing under various loading conditions including also torsional rotation. Therefore, we minimized the difference between numerically simulated and experimentally measured courses of interfragmentary movements of two axial compressive cases and two shear load cases (torsional and translational) by varying several input parameter values within their predefined bounds. The calibrated model was then qualitatively evaluated on the ability to predict physiological changes of spatial and temporal tissue distributions, based on respective in vivo data. Finally, we corroborated the model on five additional axial compressive and one asymmetrical bending load case. We conclude that our model, using distortional and dilatational strains as determining stimuli, is able to simulate fracture-healing processes not only under axial compression and torsional rotation but also under translational shear and asymmetrical bending loading conditions.     

Establishment of a knee-joint coordinate system from helical axes analysis--a kinematic approach without anatomical referencing

This study establishes a functional knee-joint coordinate system (FCS) derived from active motion. The scale invariant properties of helical axes were used in order to avoid inter-observer errors associated with the traditional anatomical referencing techniques. The algorithm was tested with six cadaveric specimens in a knee-joint motion and loading apparatus. To determine the FCS sensitivity to variable loading, rotational moments were applied to the tibia while extending and flexing the knee. Each derived FCS was compared with the clinically derived anatomical coordinate system (ACS). The FCS was reproducible when the loading condition was the same. Changing the rotational moments from internal to external affected the orientations and the positions of the FCS. The largest displacement of 20.8 mm in average occurred in the medio/lateral direction. The FCS corresponded with the ACS for all specimens and loading conditions. The origin was always located within the femur along the transepicondylar line. The orientations differed less than 16.6 degrees in average, thus allowing the use of clinical terminology. These findings suggest that the FCS might improve the ability to clinically assess kinematic alterations provided that the reference motion is reproducible.     

Histomorphological, histomorphometrical and biomechanical analysis of ceramic bone substitutes in a weight-bearing animal model

It was the purpose of this investigation to prove the biomechanical properties, the osteoconductive capacity and the degradation rate of tricalcium phosphate ( TCP), a neutralized glass ceramics (GB9N) and a composite material (GB9N+copolymers). In a weight-bearing animal model six substitutes each were implanted in the medial tibial head of the right lower leg of adult Merino-sheep in a standardized surgical technique. After nine months the implants were harvested and prepared for histomorphological and histomorphometrical investigations (undecalcified Masson Goldner staining). For additional biomechanical testing of the specimens, non-operated bone blocks from the contralateral tibia as well as native implants served as controls. No significant differences for the maximum fracture load as well as for the yield strength were detected between harvested specimens and bone blocks from the contralateral tibia. However there were marked differences to ceramics that were not implanted. All substitutes showed osteoconduction, leading to a continuous ingrowth of new formed bone. However in the composite material soft tissue could be identified within the scaffold and there were signs of ongoing bone remodeling, nine months after implantation. The bone per tissue volume of -TCP in conjunction to new bone (=percentage of trabecular bone volume plus percentage of residual substitute) was higher than for GB9N and the composite material. Nine months after implantation the percentage of residual -TCP was 48%, it was 32% for GB9N and 28% for the composite.The intention of further studies should be to accelerate the degradation rates of substitutes and to improve biomechanical properties of implants by either modifying the chemical composition or combining materials with agents as, e.g. growth factors.     

Assessing Project Success Using Subjective Evaluation Factors

Project evaluation is essential to understand and assess the key aspects of a project that make it either a success or failure. The latter is influenced by a large number of factors, and many times it is hard to measure them objectively. This paper addresses this by introducing a new method for identifying and assessing key project characteristics, which are crucial for a project's success. The method consists of a number of well-defined steps, which are described in detail. The method is applied to two case studies from different application domains and continents. It is concluded that patterns are possible to detect from the data sets. Further, the analysis of the two data sets shows that the proposed method using subjective factors is useful, since it provides an increased understanding, insight and assessment of which project factors might affect project success.