Field Testing of Abrasion Resistant Carbides

Chromium, tungsten, titanium, and vanadium carbides were investigated to determine relative cost of operation for each in an agricultural environment. For use on a ripper plow, these carbides were field tested in two different soil types; one soil having a matrix of gravel and cobblestones, and the other consisting of hard dirt and large underground rocks. Each alloy was applied to a high carbon plow point using an arc welding process. Along with the welded points, cast chromium carbide was tested. The results are given in price per acre and not solely longevity of the point. It was concluded that wear resistance is highly dependent on the abrasive environment. Each soil had a different effect on the amount of wear obtained for every alloy tested

Development of the health and economic consequences of smoking interactive model

Objective-To describe the health and economic consequences of smoking model, a user friendly, web based tool, designed to estimate the health and economic outcomes associated with smoking and the benefits of smoking cessation. Results-An overview of the development of the model equations and user interface is given, and data from the UK are presented as an example of the model outputs. These results show that a typical smoking cessation strategy costs approximately pound 1200 per life year saved and pound 22 000 per death averted. Conclusions-The model successfully captures the complexity required to model smoking behaviour and associated mortality, morbidity, and health care costs. Furthermore, the interface provides the results in a simple and flexible way so as to be useful to a variety of audiences and to simulate a variety of smoking cessation methods

A Trip to Al Aber , Quati state, Hadramaut, Eastern Aden protectorate

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Epidemiology of diabetes mellitus among 193,435 cats attending primary-care veterinary practices in England

BACKGROUND: Diabetes mellitus (DM) is a common endocrine disease of cats. The prevalence of DM in cats in England is not well‐defined. HYPOTHESIS/OBJECTIVES: To estimate the prevalence and identify risk factors for DM in a large population of cats attending primary‐care practices. ANIMALS: A cohort of 193,563 cats in the VetCompass Programme attending 118 primary‐care practices in England. METHODS: Cross‐sectional analysis of cohort clinical data. Data were extracted covering September 1st 2009 and August 31st 2014. Period prevalence of DM was calculated. Associations between risk factors and DM were assessed using logistic regression modelling. RESULTS: Of 1,128 DM cases were identified among 194,563 cats (period prevalence 0.58%; 95% confidence interval [CI] 0.54–0.61). Multivariable modelling indicated that Tonkinese (OR 4.1; 95% CI 1.8–9.6; P = .001), Norwegian Forest (odds ratio [OR] 3.5; 95% CI 1.3–9.6; P = .001) and Burmese (OR 3.0; 95% CI 2.0–4.4; P < .001) cats had increased odds of DM compared with crossbred cats. DM odds increased as bodyweight categories increased above 4 kg (P < .001), as cats aged beyond 6 years old (P < .001) and in insured cats (OR 2.0; 95% CI 1.6–2.4; P < .001) but sex was not significantly associated with DM. CONCLUSIONS AND CLINICAL IMPORTANCE: Diabetes mellitus is an important component of the primary‐care practice caseload with 1‐in‐200 cats affected. An increased risk of DM in certain cat breeds supports a genetic predisposition. These results can guide future research and preventative healthcare

Extremely sharp carbon nanocone probes for atomic force microscopy imaging

A simple and reliable catalyst patterning technique combined with electric-field-guided growth is utilized to synthesize a sharp and high-aspect-ratio carbon nanocone probe on a tipless cantilever for atomic force microscopy. A single carbon nanodot produced by an electron-beam-induced deposition serves as a convenient chemical etch mask for catalyst patterning, thus eliminating the need for complicated, resist-based, electron-beam lithography for a nanoprobe fabrication. A gradual, sputtering-induced size reduction and eventual removal of the catalyst particle at the probe tip during electric-field-guided growth creates a sharp probe with a tip radius of only a few nanometers. These fabrication processes are amenable for the wafer-scale synthesis of multiple probes. High resolution imaging of three-dimensional features and deep trenches, and mechanical durability enabling continuous operation for many hours without noticeable image deterioration have been demonstrated

Human sperm accumulation near surfaces: a simulation study

A hybrid boundary integral/slender body algorithm for modelling flagellar cell motility is presented. The algorithm uses the boundary element method to represent the ‘wedge-shaped’ head of the human sperm cell and a slender body theory representation of the flagellum. The head morphology is specified carefully due to its significant effect on the force and torque balance and hence movement of the free-swimming cell. The technique is used to investigate the mechanisms for the accumulation of human spermatozoa near surfaces. Sperm swimming in an infinite fluid, and near a plane boundary, with prescribed planar and three-dimensional flagellar waveforms are simulated. Both planar and ‘elliptical helicoid’ beating cells are predicted to accumulate at distances of approximately 8.5–22 μm from surfaces, for flagellar beating with angular wavenumber of 3π to 4π. Planar beating cells with wavenumber of approximately 2.4π or greater are predicted to accumulate at a finite distance, while cells with wavenumber of approximately 2π or less are predicted to escape from the surface, likely due to the breakdown of the stable swimming configuration. In the stable swimming trajectory the cell has a small angle of inclination away from the surface, no greater than approximately 0.5°. The trapping effect need not depend on specialized non-planar components of the flagellar beat but rather is a consequence of force and torque balance and the physical effect of the image systems in a no-slip plane boundary. The effect is relatively weak, so that a cell initially one body length from the surface and inclined at an angle of 4°–6° towards the surface will not be trapped but will rather be deflected from the surface. Cells performing rolling motility, where the flagellum sweeps out a ‘conical envelope’, are predicted to align with the surface provided that they approach with sufficiently steep angle. However simulation of cells swimming against a surface in such a configuration is not possible in the present framework. Simulated human sperm cells performing a planar beat with inclination between the beat plane and the plane-of-flattening of the head were not predicted to glide along surfaces, as has been observed in mouse sperm. Instead, cells initially with the head approximately 1.5–3 μm from the surface were predicted to turn away and escape. The simulation model was also used to examine rolling motility due to elliptical helicoid flagellar beating. The head was found to rotate by approximately 240° over one beat cycle and due to the time-varying torques associated with the flagellar beat was found to exhibit ‘looping’ as has been observed in cells swimming against coverslips

Analysis of neurodegenerative disease-causing genes in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a clinically heterogeneous disorder with a substantial burden on healthcare. Despite this, the genetic basis of the disorder is not well defined and its boundaries with other neurodegenerative diseases are unclear. Here, we performed whole exome sequencing of a cohort of 1118 Caucasian DLB patients, and focused on genes causative of monogenic neurodegenerative diseases. We analyzed variants in 60 genes implicated in DLB, Alzheimer\u27s disease, Parkinson\u27s disease, frontotemporal dementia, and atypical parkinsonian or dementia disorders, in order to determine their frequency in DLB. We focused on variants that have previously been reported as pathogenic, and also describe variants reported as pathogenic which remain of unknown clinical significance, as well as variants associated with strong risk. Rare missense variants of unknown significance were found in APP, CHCHD2, DCTN1, GRN, MAPT, NOTCH3, SQSTM1, TBK1 and TIA1. Additionally, we identified a pathogenic GRN p.Arg493* mutation, potentially adding to the diversity of phenotypes associated with this mutation. The rarity of previously reported pathogenic mutations in this cohort suggests that the genetic overlap of other neurodegenerative diseases with DLB is not substantial. Since it is now clear that genetics plays a role in DLB, these data suggest that other genetic loci play a role in this disease

Magnetic force microscopy of single crystal magnetite (Fe3O4)(abstract)

The micromagnetic domain structure of a magnetite (Fe3O4) single crystal has been studied using a magnetic force microscope (MFM). The MFM responds to the perpendicular component of the stray field above the magnetite surface. The sample was polished in the (011) plane. In this case, there are two easy magnetic axes parallel to the surface. Surface domains observed near cracks and edges have a complex closure structure (see Fig. 1), while walls seen far from such boundaries have a sinusoidal structure. Of particular interest is the presence of walls with either even or odd symmetry of the perpendicular stray field component across the transition. These can be conventionally modeled as Bloch or Neel walls, respectively. Both types of walls have been modeled and compared with the experimentally observed structures. We find the Bloch domain walls to be about 300 nm wide, nearly twice the value expected from bulk wall calculations. This distinction is consistent with a surface broadening of the domain wall due to magnetostatic effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70207/2/JAPIAU-75-10-6892-1.pd

Dynamic performance modelling of tidal stream turbines in ocean waves.

The primary aim of this work is to develop a tool to predict the lifetime performance of a tidal stream turbine. This involves the experimental validation of Blade Element Momentum Theory (BEMT) and implementation of an extended model to optimise blade design and predict performance over the operating range. Time varying non-linear upstream flows, such as wave action and velocity gradients are considered and the model is extended into the time domain to obtain the dynamic response of the rotor. In addition, to rationalise the environmental conditions that a device will encounter in its lifetime, representative sea-states and occurrences must be defined. A 1m diameter turbine is tow tested in the River Tawe. It is monitored and controlled such that the performance can be analysed over the operating range. An automated electrical control system is also tested. The results are compared to BEMT. The BEMT is numerically implemented and examined to determine its limitations. Off-optimum performance is considered. The model is extended to incorporate a time dependent flow field with additional velocity and acceleration terms to allow the consideration of wave kinematics. Resultant forces are defined and calculated for particular environmental conditions. Finally the results are interpreted to allow the estimation of lifetime loadings including peak loads and fatigue. The model is validated and a good correlation is found relative to standard BEMT. It is concluded that both a velocity gradient and a wave action may significantly reduce power output whilst increasing the loads on a system. It is also concluded that a 3 bladed rotor encounters far lower loadings than a 2 bladed equivalent over the device lifetime. It is also the intention of this study to compare and contrast various tidal stream turbine support structure concepts in terms of the suitability of each to withstand the lifetime loadings at reasonable cost. A number of support structure concepts are investigated from an impartial perspective. In conclusion there is not one concept which clearly surpasses the others in all areas