Biocompatibility and tissue regenerating capacity of crosslinked dermal sheep collagen

The biocompatibility and tissue regenerating capacity of four crosslinked dermal sheep collagens (DSC) was studied. In vitro, the four DSC versions were found to be noncytotoxic or very low in cytoxicity. After subcutaneous implantation in rats, hexamethylenediisocyanatecrcrosslinked DSC (HDSC) seldom induced an increased infiltration of neutrophils or macrophages, as compared with normal wound healing; whereas new formation of collagen was observed. DSC crosslinked with glutaraldehyde (GDSC) followed by reaction with NaBH4 shortly after implantation showed an increased infiltration of neutrophils with a deviant morphology. Furthermore, a high incidence of calcification was observed, which may explain the minor ingrowth of giant cells and fibroblasts, and the poor formation of new rat collagen. Acyl azide-crosslinked DSC (AaDSC) first induced an increased infiltration of macrophages, and then of giant cells, both with high lipid formation. AaDSC degraded at least twice as slowly as HDSC and GDSC, finally leaving a matrix of newly formed rat collagen. Samples crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide (ENDSC) induced the same mild cellular reaction as HDSC; whereas, similar to AaDSC, the degradation rate was slow and an optimal rat collagen matrix was formed. Of the crosslinked DSC samples, ENDSC seems most promising for tissue regeneration

The reception of relativity in the Netherlands

This article reviews the early academic and public reception of Albert Einstein's theory of relativity in the Netherlands, particularly after Arthur Eddington's eclipse experiments of 1919. Initially, not much attention was given to relativity, as it did not seem an improvement over Hendrik A. Lorentz' work. This changed after the arrival in Leiden of Paul Ehrenfest. Soon relativity was much studied and lead to controversy among a number of conservative intellectuals, as elsewhere in Europe. The tone of Dutch critics was much more mild, however. This can be understood when one considers Dutch neutrality during World War I. Einstein's political positions were generally positively perceived in Holland, which Dutch academics put to use in their efforts at international reconciliation abroad, and the presentation of theoretical physics at home

Rudder roll stabilization for ships

This paper describes the design of an autopilot for rudder roll stabilization for ships. This autopilot uses the rudder not only for course keeping but also for reduction of the roll. The system has a series of properties which make the controller design far from straightforward: the process has only one input (the rudder angle) and two outputs (the heading and the roll angle); the transfer from rudder to roll is non-minimum-phase; because large and high-frequency rudder motions are necessary, the non-linearities of the steering machine cannot be disregarded; the disturbances caused by the waves vary considerably in amplitude and frequency spectrum.\ud \ud In order to solve these problems a new approach to the LQG method has been developed. The control algorithms were tested by means of computer simulations, scale-model experiments and full-scale trials at sea. The results indicate that a rudder roll stabilization system is able to reduce the roll as well as a conventional fin stabilization system, while it requires less investments. Based on the results obtained in this project the Royal Netherlands Navy has decided to implement rudder roll stabilization on a series of ships under construction at this moment

Not only the butterflies: managing ants on road verges to benefit Phengaris (Maculinea) butterflies

Obligate myrmecophilic butterfly species, such as Phengaris (Maculinea) teleius and P. nausithous, have narrow habitat requirements. Living as a caterpillar in the nests of the ant species Myrmica scabrinodis and M. rubra, respectively, they can only survive on sites with both host ants and the host plant Great Burnet Sanguisorba officinalis. After having been reintroduced into a nature reserve in the Netherlands in 1990, both butterfly species expanded their distribution to linear landscape elements such as road verges and ditch edges outside this reserve. As additional habitat of both butterfly species, vegetation management of these landscape elements became important. Our results show that a management beneficial for Phengaris butterflies should aim to increase the nest density of Myrmica species, at the same time reducing the density of nests of the competitor Lasius niger or at least keeping them at a low density. Unfavourable grassland management under which L. niger thrives, includes not mowing or flail-cutting the grass, or depositing dredgings along the side of the ditch. Management favourable for the two Myrmica species differs, demanding some flexibility if both species are to benefit. M. scabrinodis is best supported with early mowing of the road verge vegetation or late mowing in the nature reserve, both of which result in an open vegetation and warm microclimate. In contrast, the nest sites of M. rubra should be left undisturbed during the summer, and mown in late autumn. Mowing of butterfly habitat should be avoided between mid-June and mid-September as this would remove the flowerheads of the Sanguisorba plants, on which the butterflies lay their eggs

Some comments on Laplacian gauge fixing

Laplacian gauge fixing was introduced to find a unique representative of the gauge orbit, which on the lattice could be implemented by a ``finite'' algorithm. What was still lacking was a perturbative formulation of this gauge, which will be presented here. However, renormalizability is still to be demonstrated. For torodial and spherical geometries a detailed comparison with the Landau (or Coulomb) gauge will be made.Comment: Contribution to Lattice '94, 3 pages PostScrip

The importance of internal communication in organizational change: Case study of the structural change in a Belgian government agency

Internal communication is an essential element to create willingness to change in organizations (Elving 2005a, 2005b; Clampitt et al. 2000; Armenakis et al. 2007). In this paper, we present the results of a mixed method research assessing change communication in a Belgian governmental institution which recently implemented a change in its organizational structure. Our approach to the data was twofold. The descriptive, quantitative first part of the research relies on a survey of 718 staff members involved in the change. The survey consists of 30 questions assessing the internal communication about the change, and the staff’s willingness to change. The questionnaire is based on existing instruments - such as the ICA audit, the scales of Armenakis et al (2007) and Wanous et al (2000). We addressed the following research questions: RQ1 - To what extent are staff members willing to go along with the change? RQ2 - To what extent are staff members satisfied with the internal communication regarding the change? Second, we conducted 14 semi-structured in-depth interviews with staff members, in which we further explored notable findings of the survey. The interviews (each about 20 to 30 minutes) were conducted in the period from June 25, 2014 to July 9, 2014 and aimed at answering the following research question: RQ3 - To what extent has the internal communication had an impact on staff members’ willingness to change or change resistance ? Our findings confirm that a negative assessment of the internal communication correlates with a higher degree of change resistance, but also -if not more so- the results reveal the the extent to which individual self interest acts cause resistance to change. In conclusion, we open up the debate about the role of internal communication in signaling and preventing this from happening. __________ 50-word summary: This paper presents the results of a mixed method research assessing change communication in a Belgian governmental institution which recently implemented a change in its organizational structure. The main finding is that a crucial role is reserved for internal communication in preventing self-interest acts as a brake on change readiness

Forecasting Financial Extremes: A Network Degree Measure of Super-exponential Growth

Investors in stock market are usually greedy during bull markets and scared during bear markets. The greed or fear spreads across investors quickly. This is known as the herding effect, and often leads to a fast movement of stock prices. During such market regimes, stock prices change at a super-exponential rate and are normally followed by a trend reversal that corrects the previous over reaction. In this paper, we construct an indicator to measure the magnitude of the super-exponential growth of stock prices, by measuring the degree of the price network, generated from the price time series. Twelve major international stock indices have been investigated. Error diagram tests show that this new indicator has strong predictive power for financial extremes, both peaks and troughs. By varying the parameters used to construct the error diagram, we show the predictive power is very robust. The new indicator has a better performance than the LPPL pattern recognition indicator.Comment: 16 pages, 6 figure

Total-liver-volume perfusion CT using 3-D image fusion to improve detection and characterization of liver metastases

The purpose of this study was to evaluate the feasibility of a totalliver- volume perfusion CT (CTP) technique for the detection and characterization of livermetastases. Twenty patients underwent helical CT of the total liver volume before and 11 times after intravenous contrast-material injection. To decrease distortion artifacts, all phases were co-registered using 3-D image fusion before creating blood-flow maps. Lesion-based sensitivity and specificity for liver metastases of first the conventional four phases (unenhanced, arterial, portal venous, and equilibrium) and later all 12 phases including blood-flow maps were determined as compared to intraoperative ultrasound and surgical exploration. Arterial and portal venous perfusion was calculated for normalappearing and metastatic liver tissue. Total-liver-volume perfusion values were comparable to studies using single-level CTP. Compared to fourphase CT, total -liver-volume CTP increased sensitivity to 89.2 from 78.4% (P=0.046) and specificity to 82.6 from 78.3% (P=0.074). Total - liver-volume CTP is a noninvasive, quantitative, and feasible technique. Preliminary results suggest an improved detection of liver metastases for CTP compared to four-phase CT

A Power Efficient Audio Amplifier Combining Switching and Linear Techniques

Integrated Class D audio amplifiers are very power efficient, but require an external filter which prevents further integration. Also due to this filter, large feedback factors are hard to realise, so that the load influences the distortion- and transfer characteristics. The amplifier presented in this paper consists of a switching part that contains a much simpler filter, and a linear part that ensures a low distortion and flat frequency response. A 30W version was realised. The switching part of the amplifier was integrated in a BCD process. Together with a linear part and with a loudspeaker as load, it has a flat frequency response +/- 0.3dB, a dissipation that is up to 5 times lower than a traditional class AB audio amplifier, and a distortion of <0.02% over power and frequency range