Double-brush Langmuir-Blodgett monolayers of α-helical diblock copolypeptides

The synthesis of amphiphilic diblock copolypeptides consisting of poly(α-l-glutamic acid) (PLGA) and poly(γ-methyl-l-glutamate-ran-γ-stearyl-l-glutamate) with 30 mol % of stearyl substituents (PMLGSLG) and their monolayer behavior at the air-water interface have been studied. PLGA-b-PMLGSLG was synthesized via a diblock copolymer precursor consisting of poly(γ-tert-butyl-l-glutamate) (PtBuLG) and PMLGSLG blocks, with the tert-butyl group as a mild acid-labile protecting group for the carboxylic acid. The polymerization conditions were found to influence the α-helix to β-sheet content ratio and can be tuned to significantly enhance the diblock copolypeptide helicity. Purely α-helical PtBuLG-b-PMLGSLG diblock copolymers were successfully prepared. After removal of the tert-butyl group, the study of the PLGA-b-PMLGSLG amphiphilic diblock copolymers in Langmuir monolayers and Langmuir-Blodgett films demonstrated the formation of a stable α-helical double-brush structure, with the helices tilted away from the substrate surface. These double-brush monolayers combine the unique properties arising from the unidirectionally aligned helix macrodipole and the liquid-like features of the side chain mantle of the PMLGSLG block. Such systems are promising for thin film applications requiring incorporation and orientation of bio- and optical molecules.     

Socio-technical PSS development to improve functionality and usability—Sketch planning using a Maptable

Planning Support Systems (PSS) for collaborative sketch planning have not become widely used in planning practice. Important reasons are inadequate functionality and usability. In this article we question if following a socio-technical method in PSS development could lead to PSS with better functionality and usability than following a traditional systems engineering method, as is sometimes suggested in literature. The former method involves close cooperation with users, whereas the latter does not. This article describes an empirical study of this question. The article describes the development, application and evaluation of two PSS for sketch planning, one developed by following the traditional systems engineering method and the other by following the socio-technical method. The PSS integrate drawing and sketching with basic geographic information system functionality and use an innovative hardware interface called Maptable. The evaluation results show that the traditionally developed PSS was immediately rejected by planning practitioners due to poor functionality and usability, whereas the PSS developed with a socio-technical approach was much more acceptable. Intense cooperation with users in agreement with the socio-technical method appeared to improve the analysis of planning tasks and user needs, leading to a PSS with a sophisticated and dedicated architecture. This PSS was considered more functional and usable than the traditionally developed PSS. In addition, the socio-technically developed PSS offers some benefits over conventional planning methods. In current state the PSS is suitable for use by professionals, and it is being further developed aiming to make it suitable for supporting collaborative planning with citizens.     

Determination of in vivo rat muscle Gd-DTPA relaxivity at 6.3 T

For the in vivo relaxivity of Gd-DTPA at 6.3 T in rat muscle a value of 2.7±0.5 (mM s)⁻¹ was found, and for the in vitro value in water 3.00±0.56 (mM s)⁻¹ at 37°C. The temperature dependence of the in vitro relaxivity was −0.087 (mM s °C)⁻¹. The relation between1/T ₁ and the tissue Gd-DTPA concentration is linear for the normally used in vivo Gd-DTPA concentration range     

An ethical perspective on euthanasia and assisted suicide in The Netherlands from a nursing point of view

An attempt has been made to find out if the organic matter digestibility of tropical feeds and fodders can be predicted from the results of an in vitro cellulase enzyme technique. The in vivo digestibility coefficient of 27 tropical feeds and fodders was determined in wethers. The enzyme insoluble organic matter content of these feeds was determined using a cellulase enzyme technique. The indigestible OM (g/kg feed DM) in vivo (y) was plotted against enzyme insoluble organic matter (g/kg DM) (x). The equation is y = 60 + 0.817x, R2 = 0.95; RSD = 32 g/kg DM. Equations for predicting DOM (g/kg DM) and digestibility of OM (%) are calculated. The testing of the equation on an independent data base of 40 individual feeds and fodders showed that the validity of the equation is fairly general.     

Extending the Gain Bandwidth of Combined Raman-Parametric Fiber Amplifiers Using Highly Nonlinear Fiber

The authors demonstrate extended flat gain bandwidth by combining Raman and parametric processes. The increase in bandwidth is accomplished by extending the Raman gain region to the longer wavelength side of the Raman gain by using parametric gain. Two different configurations of the amplifier are investigated. The associated gain and bit error performance is characterized. A gain of about 15 dB, with gain flatness of 5 dB is measured.     

Speed choice and mental workload of elderly cyclists on e-bikes in simple and complex traffic situations: A field experiment

To study the speed choice and mental workload of elderly cyclists on electrical assisted bicycles (e-bikes) in simple and complex traffic situations compared to these on conventional bicycles, a field experiment was conducted using two instrumented bicycles. These bicycles were identical except for the electric pedal support system. Two groups were compared: elderly cyclists (65 years of age and older) and a reference group of cyclists in middle adulthood (between 30 and 45 years of age). Participants rode a fixed route with a length of approximately 3.5 km on both bicycles in counterbalanced order. The route consisted of secluded bicycle paths and roads in a residential area where cyclist have to share the road with motorized traffic. The straight sections on secluded bicycle paths were classified as simple traffic situations and the intersections in the residential area where participants had to turn left, as complex traffic situations. Speed and mental workload were measured. For the assessment of mental workload the peripheral detection task (PDT) was applied. In simple traffic situations the elderly cyclists rode an average 3.6 km/h faster on the e-bike than on the conventional bicycle. However, in complex traffic situations they rode an average only 1.7 km/h faster on the e-bike than on the conventional bicycle. Except for the fact that the cyclists in middle adulthood rode an average approximately 2.6 km/h faster on both bicycle types and in both traffic conditions, their speed patterns were very similar. The speed of the elderly cyclists on an e-bike was approximately the speed of the cyclists in middle adulthood on a conventional bicycle. For the elderly cyclist and the cyclists in middle adulthood, mental workload did not differ between bicycle type. For both groups, the mental workload was higher in complex traffic situations than in simple traffic situations. Mental workload of the elderly cyclists was somewhat higher than the mental workload of the cyclists in middle adulthood. The relatively high speed of the elderly cyclists on e-bikes in complex traffic situations and their relatively high mental workload in these situations may increase the accident risk of elderly cyclist when they ride on an e-bike.     

Lightness, brightness, and brightness contrast: 1. Illuminance variation

Changes of annulus luminance in traditional disk-and-annulus patterns are perceptually ambiguous; they could be either reflectance or illuminance changes. In more complicated patterns, apparent reflectances are less ambiguous, letting us place test and standard patches on surrounds perceived to be different grays. Our subjects matched the apparent amounts of light coming from the patches (brightnesses), their apparent reflectances (lightnesses), or the brightness differences between the patches and their surrounds (brightness contrasts). The three criteria produced quantitatively different results. Brightness contrasts matched when the patch/surround luminance ratio of the test was approximately equal to that of the standard. Lightness matches were illumination invariant but were not exact reflectance matches; the different surrounds of test and standard produced a small illumination-invariant error. This constant error was negligible for increments, but, for decrements, it was approximately 1.5 Munsell value steps. Brightness matches covaried substantially with illuminance.