Parallelisation of suboptimal spectrum search

The authors suggest that effective algorithms for spectrum search, such as those used for detecting spread spectrum signals, may be derived by selecting suboptimal algorithms and then recovering some of the lost efficacy through parallelisation methods. This thesis is motivated by considering a simple yet meaningful example of a spectrum search technique that exhibits what at first may seem to be counterintuitive behaviour.<>     

Ion implantation doping of OMCVD grown GaN

Doping by ion implantation using Si, O, Mg, and Ca has been studied in single crystal semi-insulating and n-type GaN grown on a-sapphire substrates. The n-and p-type dopants used in this study are Si and O; Mg and Ca, respectively. Room temperature activation of Si and O donors has been achieved after 1150°C annealing for 120 s. The activation of Mg and Ca acceptors is too low to measure at both room temperature and 300°C. Using higher doses to achieve a measurable p-type conduction increases the amount of damage created by the implantation. Rutherford back scattering measurements on this material indicate that the damage is still present even after the maximum possible heat treatment. Secondary ion mass spectrometry measurements have indicated a redistribution in the measured profiles of Mg due to annealing.     

Electrospun poly(aspartic acid) gel scaffolds for artificial extracellular matrix

Biocompatible synthetic polymer gel scaffolds for tissue engineering and regenerative medicine were prepared by reactive electrospinning. Protein‐like nano‐ and microfibres from chemically crosslinked polysuccinimide were obtained. Fibrous poly(aspartic acid) gels with size similar to that of extracellular matrix were obtained by hydrolysis of the polysuccinimide gel fibres. The effects of process parameters on fibre morphology (diameter, swelling degree) and chemical structure were investigated. Sub‐micrometre‐sized biocompatible fibrous scaffolds from a poly(amino acid) is a novel approach with great promise in several biomedical applications due to the tailor‐made synthetic nature, extreme purity and possibility of production on a large scale. © 2014 Society of Chemical Industry     

Driving behaviors in early stage dementia: A study using in-vehicle technology

According to the Alzheimer's Association (2011), (1) in 8 people age 65 and older, and about one-half of people age 85 and older, have Alzheimer's disease in the United States (US). There is evidence that drivers with Alzheimer's disease and related dementias are at an increased risk for unsafe driving. Recent advances in sensor, computer, and telecommunication technologies provide a method for automatically collecting detailed, objective information about the driving performance of drivers, including those with early stage dementia. The objective of this project was to use in-vehicle technology to describe a set of driving behaviors that may be common in individuals with early stage dementia (i.e., a diagnosis of memory loss) and compare these behaviors to a group of drivers without cognitive impairment. Seventeen drivers with a diagnosis of early stage dementia, who had completed a comprehensive driving assessment and were cleared to drive, participated in the study. Participants had their vehicles instrumented with a suite of sensors and a data acquisition system, and drove 1–2 months as they would under normal circumstances. Data from the in-vehicle instrumentation were reduced and analyzed, using a set of algorithms/heuristics developed by the research team. Data from the early stage dementia group were compared to similar data from an existing dataset of 26 older drivers without dementia. The early stage dementia group was found to have significantly restricted driving space relative to the comparison group. At the same time, the early stage dementia group (which had been previously cleared by an occupational therapist as safe to drive) drove as safely as the comparison group. Few safety-related behavioral errors were found for either group. Wayfinding problems were rare among both groups, but the early stage dementia group was significantly more likely to get lost.     

Soft X‐ray Ptychographic Imaging and Morphological Quantification of Calcium Silicate Hydrates (C–S–H)

Morphological details of calcium silicate hydrate (C–S–H) stemming from the hydration process of Portland cement (PC) phases are crucial for understanding the PC‐based systems but are still only partially known. Here we introduce the first soft X‐ray ptychographic imaging of tricalcium silicate (C₃S) hydration products. The results are compared using both scanning transmission X‐ray and electron transmission microscopy data. The evidence shows that ptychography is a powerful method to visualize the details of outer and inner product C–S–H of fully hydrated C₃S, which have fibrillar and an interglobular structure with average void sizes of 20 nm, respectively. The high‐resolution ptychrography image enables us to perform morphological quantification of C–S–H, and, for the first time, to possibly distinguish the contributions of inner and outer product C–S–H to the small angle scattering of cement paste. The results indicate that the outer product C–S–H is mainly responsible for the q^?3 regime, whereas the inner product C–S–H transitions to a q^?2 regime. Various hypotheses are discussed to explain these regimes.     

Liquid flow in molds with prelocated fiber mats

The mechanism associated with mold filling in the manufacture of structural RIM (SRIM) and resin transfer molding (RTM) composites is studied by means of flow visualization and pressure drop measurements. To facilitate this study, an acrylic mold with a variable cavity was constructed and the flow patterns of nonreactive fluid flowing through various layers, types, and combinations of preplaced glass fiber reinforcement mats were photographed for both evacuated and nonevacuated molds. The pressure drops in the flow through a single type of reinforcement (e.g., a continuous strand random fiber mat) and also a combination of reinforcement types (e.g., a stitched bidirectional mat in combination with a random fiber mat) were recorded at various flow rates to simulate high-speed feeding processes (e.g., SRIM) and low-speed feeding processes (e.g., RTM). By changing the amount of reinforcement placed into the mold, the permeabilities of the different types and combinations of glass fiber mats were obtained as a function of porosity. It is shown that partially evacuating the mold cavity decreases the size of bubbles or voids in the liquid, but ultimately increases the maximum pressure during filling. The results also show that glass fiber mats exhibit anisotropic permeabilities with the thickness permeability, K_z, being extremely important and often the determining factor in the pressure generated in the mold during filling.     

Zur endogene Lipidperoxidation bei diätetischer Belastung des Masthuhns

Endogenous Lipid Peroxidation in Broiler Chickens under Dietary Loads Growing broiler chickens were fed a Vitamin E-deficient diet containing 10% reesterified triglyceride from soy-bean-oil. Six groups with day-old broiler chicken were supplemented with 0, 20 or 100 ppm of vitamin E. On each vitamin level one group was fed with the fresh fat, the other was supplied with the fat being oxidized. Clinical data and development of body weight were registered. The animals were euthanised after 3 weeks. Pentane production of liver mitochondria and microsomes was measured and tocopherol concentrations were determined as well as the GSH-PX-activity in liver cytosol and plasma. Deficiency of vitamin E together with a high level of dietary linoleic acid leads to an imbalance in peroxidative and antioxidative metabolism and finally to disease. It is discussed if the clinical signs after consumption of linoleic acid-rich oxidized oils are caused by specific toxic secundary products.     

Influence of the irradiation temperature on the dosimetric and high temperature TL peaks of Al2O3:C

The TL glow curves of Al2O3:C crystals have been investigated as a function of the irradiation temperature. The nature of the observed TL peaks has been studied by optical annealing. The filling of traps was found strongly dependent on the irradiation temperature in the case of UV exposure, which has been explained by the temperature dependence of the photoionisation of F centres. This latter phenomenon could have a part in the luminescence quenching and UV bleaching of F centres.     

Collateral blood supply through the ophthalmic artery: a steal phenomenon analyzed by color Doppler imaging

OBJECTIVE: This study aimed to evaluate the retrobulbar circulatory effects of reversed ophthalmic artery flow (ROAF) on the ophthalmic artery branches by means of color Doppler imaging. DESIGN: The design was a case-controlled study. PARTICIPANTS: Among 56 consecutive patients with severe (>70% stenosis) occlusive carotid artery disease, 15 patients (26.8%) with ROAF were identified. The control group consisted of 15 patients with similar degrees of carotid artery stenosis and forward ophthalmic artery flow. INTERVENTION: Arteriography and measurement of the retrobulbar hemodynamic parameters with color Doppler imaging were performed. MAIN OUTCOME MEASURES: Blood flow velocities and resistive index in the ophthalmic, central retinal, and temporal short posterior ciliary arteries were measured. RESULTS: Arteriography confirmed the diagnosis of ROAF in all 15 patients. There was no patient with ROAF diagnosed by arteriography and not diagnosed by color Doppler imaging. The frequency of bilateral severe occlusive carotid artery disease was significantly higher in the ROAF group (40%) compared to the control group (6.6%) (P = 0.04). Patients with ROAF showed significantly reduced vascular resistance in the ophthalmic artery (P = 0.03), higher vascular resistance, and lower blood flow velocities in the central retinal and temporal short posterior ciliary arteries (P < 0.05). CONCLUSION: This study suggests that patients with ROAF show a steal phenomenon, characterized by a shunt to the low-resistance intracranial circuit and reduction of retrobulbar blood flow.