The effect of local cooling on growth and water content of plants.

In maize cv. Pioneer 395 grown in controlled environment in Hoagland solution at 20 deg C with 18-h photoperiods, low-temperature treatment of localized parts of the plant inhibited leaf elongation to an extent dependent on the site of cooling. Root temperatures of 5 deg C decreased leaf elongation as a result of water shortage and consequent retardation of cell extension. Plant osmotic potential increased and leaf elongation then resumed. When roots were cooled rapidly to 2-2.5 deg C the lower leaves died as a result of irreversible wilting, but with slow cooling the leaves survived. The response to these low temperatures was considerably less in older than in younger plants. Low temperatures at leaf meristem level directly reduced leaf elongation by acting on cell division and cell extension; the effect tended to increase with time. Local cooling above the meristem temporarily retarded growth by inhibiting carbohydrate translocation (demonstrated using 14CO2), but resulted in an increased concentration gradient which partly offset the effect of temperature. Cell extension was considerably inhibited, cell division probably only slightly. (Abstract retrieved from CAB Abstracts by CABI’s permission

Genetic obesity:Disorders and diagnostics

Obesity is a common disease with serious consequences for the health and well-being of patients. In a small proportion of people with excessive weight, a change in genetic material is the main cause of the obesity. In this thesis, the results of genetic testing for these rare obesity disorders are described. Because of the high prevalence of obesity, it is currently impossible to perform genetic diagnostics in all people with obesity. An improved insight in the clinical phenotype of patients with a genetic obesity disorder is therefore needed to determine which patients should undergo genetic testing. Moreover, the impact of diagnosing these disorders is described in this thesis. Increased knowledge about the underlying mechanisms offers great opportunities for the development of novel drug therapy for obesity

Some effects of vernalization on the reproductive capacity of Lolium perenne L.

Vernalization requirements of grasses are reviewed, and data are given on experiments with perennial ryegrass showing considerable differences in vernalization behaviour between clones. Incomplete vernalization often increased the number of spikelets/inflorescence. Effects of soluble carbohydrate level are discussed. Experiments in which plants of perennial ryegrass were transferred into and out of a glasshouse during Jan.-Mar. indicated that the vernalization stimulus was not translocated between tillers. (Abstract retrieved from CAB Abstracts by CABI’s permission

UNDERSTANDING CHASSIS INPUTS FROM THE REAR SUSPENSION OF A SNOWMOBILE

Today’s snowmobile industry faces great challenges in the field of noise & vibration. The area of main concern is the pass-by noise restriction defined by the Society of Automotive Engineers (SAE) test standard J192, with a maximum sound pressure level of 78 dB(A) being required by many states and national parks. To continue meet or beat this requirement without effecting machine performance, a deeper understanding of the sound transfer paths is required. This thesis examines the transfer paths created by the tunnel, rear suspension, drive shaft, and rubber composite track, with the primary source being suspension input through the ground. Using a combination of field experiments and analytical modeling, perspective was gained on which suspension and drive elements create the primary transfer paths. With further understanding of these paths, industry can tailor and fine-tune the approaches taken in to control overall noise output

Responses of young cucumber plants to root and shoot temperatures.

Young cucumber plants were grown at all combinations of three shoot and three root temperatures (12, 18 and 24 degrees C). Growth and development of vegetative parts and fruits were studied after a temperature treatment of 14 days or 28 days. Shoot temperature has a positive effect on the rate of leaf development, while the rate of leaf initiation is influenced to a minor degree. There is only a small effect of root temperature on the rate of leaf appearance. The number of fruits is increased with increasing shoot and root temperature, the shoot temperature being more important than the root temperature. The total fruit fresh weight also increases with increasing shoot temperature; at 24 degrees C shoot temperature, the fruit weight shows an optimum at 18 degrees C root temperature. Distribution of dry matter is also dependent on root temperature and to a greater extent on shoot temperature. A shoot temperature of 18 degrees C is optimal for root growth, while 24 degrees C shoot or root temperature is sub-optimal for shoot growth. Increase in shoot temperature has a stronger positive effect on stem growth than on leaf dry weight. The relative effect of root temperature on stem growth equals that on leaf growth. Growth analysis shows that increase in relative growth rate at higher shoot and root temperatures under low light conditions is achieved by increasing the specific leaf area. This adaptation to changes in shoot or root temperature occurs within 14 days. ADDITIONAL ABSTRACT: Cucumber plants (cvs Farbio and Sandra, both F1 hybrids) were grown at 12, 18 and 24 deg C shoot and root temperatures in all combinations. The number of fruits was increased with increasing shoot and root temperature, the shoot temperature being the more important. Total fruit fresh weight also increased with rising shoot temperature. At 24 deg shoot temperature, however, fruit weight was optimum with 18 deg root temperature. Also, at 24 deg shoot temperature, the lower the root temperature the more fruits were present at a given leaf number. A shoot temperature of 18 deg was optimal for root growth but 24 deg shoot or root temperature was still suboptimal for shoot growth. An increase in shoot temperature had a stronger positive effect on stem growth than on leaf dry weight. The relative effect of root temperature on stem growth was equal to that on leaf growth. Growth analysis showed that leaves became thinner at higher temperatures. This adaptation to changes in shoot or root temperature occurred within 14 days. Cvs showing the highest specific leaf area at the desired temperature seem to be the best qualified to give the optimal relative growth rate at the low light intensities prevailing in early spring. (Abstract retrieved from CAB Abstracts by CABI’s permission

One-step deposition of nano-to-micron-scalable, high-quality digital image correlation patterns for high-strain in-situ multi-microscopy testing

Digital Image Correlation (DIC) is of vital importance in the field of experimental mechanics, yet, producing suitable DIC patterns for demanding in-situ mechanical tests remains challenging, especially for ultra-fine patterns, despite the large number of patterning techniques in the literature. Therefore, we propose a simple, flexible, one-step technique (only requiring a conventional deposition machine) to obtain scalable, high-quality, robust DIC patterns, suitable for a range of microscopic techniques, by deposition of a low melting temperature solder alloy in so-called 'island growth' mode, without elevating the substrate temperature. Proof of principle is shown by (near-)room-temperature deposition of InSn patterns, yielding highly dense, homogeneous DIC patterns over large areas with a feature size that can be tuned from as small as 10nm to 2um and with control over the feature shape and density by changing the deposition parameters. Pattern optimization, in terms of feature size, density, and contrast, is demonstrated for imaging with atomic force microscopy, scanning electron microscopy (SEM), optical microscopy and profilometry. Moreover, the performance of the InSn DIC patterns and their robustness to large deformations is validated in two challenging case studies of in-situ micro-mechanical testing: (i) self-adaptive isogeometric digital height correlation of optical surface height profiles of a coarse, bimodal InSn pattern providing microscopic 3D deformation fields (illustrated for delamination of aluminum interconnects on a polyimide substrate) and (ii) DIC on SEM images of a much finer InSn pattern allowing quantification of high strains near fracture locations (illustrated for rupture of a Fe foil). As such, the high controllability, performance and scalability of the DIC patterns offers a promising step towards more routine DIC-based in-situ micro-mechanical testing.Comment: Accepted for publication in Strai