Lower limb ischaemia in the octogenarian: is limb salvage surgery worthwhile?

Vascular surgeons are being asked to manage vascular disease in an increasingly elderly population, and advanced age may be considered a relative contraindication to limb salvage surgery with an amputation seeming the preferred option. We present a review of 50 patients over the age of 80 years, presenting with ischaemic rest pain, ulceration or gangrene of the lower extremity. Six patients were treated conservatively, four of whom died during the same admission. Only two patients proved suitable for transluminal angioplasty as the sole curative procedure. Twelve patients (24%) underwent primary amputation with a perioperative mortality of 3/12 (25%). Five patients (10%) had an iliac bypass procedure, and 25 patients (50%) were considered suitable for infrainguinal bypass. Of the latter group 14 had femoropopliteal bypasses, and 11 had femorodistal bypasses with an overall perioperative mortality of 3/25 (12%). Mortality at 6 months was high (33%) and was similar in both the grafted and amputation groups. Patients having reconstruction fared well in terms of independent mobility, use of long-term care, and length of hospital stay. Patients over 80 years of age with critical ischaemia should not be denied the opportunity of vascular reconstruction.     

Nourishing green minds in the land of oil

Climate change, global warming and the increasing in oil price are issues that concern everyone lately. Renewable energy is the solution for a safe and efficient environment for the new generations. Renewable energy sources are sustainable and are zero carbon emission.In order to deploy these sources efficiently, expertise in this field must be provided. This is accomplished by educating the young generations to all related issues regarding these sources and the related technologies. This paper describes the experience of introducing renewable energy in the curriculum for undergraduate students in the United Arab Emirates (UAE) and the steps taken to enhance the learning process. It only represents the first stage of implementing green energy education into an engineering technology program and highlights the impact of this experience on the students with respect to the environment and the community. Such experience is an example that can be followed in order to promote renewable energy technologies and to develop the expertise in this field in a country that has just started to embrace renewable energy.     

Serial section electron tomography: a method for three-dimensional reconstruction of large structures

We present a method for combining single axis tomography and serial sectioning techniques to derive a three-dimensional reconstruction of large structures at electron microscopic resolution. This serial-tomography method allows the use of sufficiently thin sections to achieve adequate resolution with electron tomography, yet enables the generation of large reconstructions with considerably fewer sections than would be required using a serial thin section reconstruction technique. Serial thick sections (1-2 microns) are cut through the structure of interest, tomographic volume reconstructions are obtained for each section from a single axis tilt series, and the resulting series of volumes are then aligned and combined to form a single large volume. The serial-tomography method is illustrated with several samples, including red blood cells, the Golgi apparatus, and a spiny dendrite of a cortical pyramidal neuron. In some of these samples, the reconstruction is compared to correlated light microscopic views. The resulting large volume reconstructions appear to represent accurately the size and shape of objects such as red blood cells and spiny dendrites. The continuity of complex, tortuous structures such as the Golgi apparatus is also maintained across serial volumes. These examples demonstrate that it is possible to align and link a series of tomographic volumes accurately and that serial-tomography is a useful method for reconstructing relatively large structures without resorting to large numbers of serial thin sections.     

Photoluminescence studies of heteroepitaxial gaas on si

We present a systematic study of the photoluminescence of undoped GaAs layers deposited by MOCVD on Si substrates. The study includes an examination of substrate and layer thickness effects in thin GaAs layers, and a detailed investigation of the stress effects on the intrinsic band-edge transitions in thicker samples. For sample thickness,t ≤ 0.5(μm), we observe strong midgap emission bands associated with defects close to the interface. These bands depend strongly on the nature of the Si substrate. The crystal quality improves with sample thickness, and fort ≥ 0.5 μm the emission is dominated by lines in the band edge region which are relatively independent of substrate preparation. Photoluminescence excitation spectra reveal that the highest energy line is due to an intrinsic exciton transition, and that a splitting of this line observed fort ≥ 2 μm reflects the presence of two different regions of strain in the material. The magnitude of the strain is estimated from the shift of the exciton lines relative to unstrained GaAs, and is found to be consistent with an upper limit provided by the thermal expansion mismatch between GaAs and Si.     

Kangaroos Avoid Eating Seedlings with or Near Others with Volatile Essential Oils

Preliminary studies indicate that western grey kangaroos browse seedlings of non-Myrtaceae species rather than Myrtaceae. Seven morphologically-matched species pairs of Myrtaceae/non-Myrtaceae placed at three field sites showed that kangaroos avoided the essential-oil-containing Myrtaceae, but readily consumed the matched essential-oil-lacking non-Myrtaceae. The one exception (Pittosporaceae) had limited herbivory and was later found to possess two essential oils in its leaves. Gas chromatography and mass-spectra showed the seven Myrtaceae plants contain between 2 and 9 essential oils in their leaves, particularly the highly volatile monoterpene, 2,5-dimethyl-3-methylene-1,5-heptadine. Three of the above species pairs were used to gauge their effectiveness as nurse plants for a highly palatable legume. Plants placed beside Myrtaceae nurse plants were less browsed than those placed beside non-Myrtaceae nurse plants. We conclude that western grey kangaroos use olfactory cues to avoid foliage containing potentially toxic essential oils, and that this also has implications for seedling recruitment patterns in regenerating communities.     

Analysis of Nuclear Material by Alpha Spectroscopy with a Transition-Edge Microcalorimeter

We present measurements from a cryogenic microcalorimeter designed to detect alpha particles. The enhanced resolution of microcalorimeter alpha detectors will provide new capabilities for actinide analysis. We demonstrate a spectral resolution of 2.4 keV full width at half maximum (FWHM) for 5.3 MeV alpha particles from a ²¹⁰Po source. In addition, we present an alpha spectrum from ²⁰⁹Po showing the first direct measurement of decay into the ²⁰⁵Pb ground state. Finally, measurements of 100 keV gamma-rays from a Gd source show an ultimate alpha particle resolution of 159 eV to be achievable which may provide an avenue for investigating ion energy loss mechanisms in bulk materials.