2,554 research outputs found
A Sixth-Order Extension to the MATLAB Package bvp4c of J. Kierzenka and L. Shampine
A new two-point boundary value problem algorithm based upon the MATLAB bvp4c package of Kierzenka and Shampine is described. The algorithm, implemented in a new package bvp6c, uses the residual control framework of bvp4c (suitably modified for a more accurate finite difference approximation) to maintain a user specified accuracy. The new package is demonstrated to be as robust as the existing software, but more efficient for most problems, requiring fewer internal mesh points and evaluations to achieve the required accuracy
Long stroke pump
A very high pressure pump apparatus which minimizes wear on the seals thereof and on valves connected thereto, by utilizing a very long stroke piston rod whose opposite ends are received in long cylinders. An electric motor which drives the rod, includes a rotor with a threaded aperture that receives a long threaded middle portion of the rod, so that as the rotor turns it advances the rod
Modeling the magnetic pickup of an electric guitar
The magnetic pickup of an electric guitar uses electromagnetic induction to convert the motion of a ferromagnetic guitar string into an electrical signal. Although the magnetic pickup is often cited as an everyday application of Faraday\u27s law, few sources mention the distortion that the pickup generates when converting string motion into an electric signal, and even fewer attempt to analyze and explain this distortion. By modeling the magnet and ferromagnetic wire as surfaces with magnetic charge, an intuitive model that accurately predicts the output of a magnetic guitar pickup can be constructed. Moreimportantly, this model can be understood and manipulated by students at the undergraduate level and provides an excellent learning tool due to its straightforward mathematics and intuitive algorithm. Experiments show that it predicts the change in a magnetic field due to the presence of a ferromagnetic wire with a high degree of accuracy
Self-medications with potential abuse in the Middle East: a systematic literature review
Self-medication (SM) is highly prevalent in the Middle East. However, regulations in the Middle East are not always enforced and therefore many prescription medicines can be purchased as SM, resulting in potential abuse of many medicines. The aim of this article, therefore, was to undertake a comprehensive review to identify the different types of self-medications involved in abuse in the Middle East and to identify harms related to SM abuse. An extensive review of the published literature pertaining to the subject (1990–2015) was conducted using PubMed, Web of Science, Cochrane and Google Scholar databases for OTC medication abuse in the Middle East. Twenty two papers were identified. Medications involved in SM abuse included: psychoactive prescription-only medicines, codeine-containing products, tramadol, anabolic steroids, sedative antihistamines, decongestants and laxatives. Moreover, studies in the region rarely reported harms related to SM abuse and strategies to limit this abuse. Potential SM abuse involving a range of medicines is a public health problem in the Middle East. Future interventions and regulations should be applied to limit the expansion of SM use and potential abuse
Flexibility in the receptor-binding domain of the enzymatic colicin E9 is required for toxicity against Escherichia coli cells
The events that occur after the binding of the enzymatic E colicins to Escherichia coli BtuB receptors that lead to translocation of the cytotoxic domain into the periplasmic space and, ultimately, cell killing are poorly understood. It has been suggested that unfolding of the coiled-coil Mull receptor binding domain of the E colicins may be an essential step that leads to the loss of immunity protein from the colicin and immunity protein complex and then triggers the events of translocation. We introduced pairs of cysteine mutations into the receptor binding domain of colicin E9 (ColE9) that resulted in the formation of a disulfide bond located near the middle or the top of the R domain. After dithiothreitol reduction, the ColE9 protein with the mutations L359C and F412C (ColE9 L359C-F412C) and the ColE9 protein with the mutations Y324C and L447C (ColE9 Y324C-L447C) were slightly less active than equivalent concentrations of ColE9. On oxidation with diamide, no significant biological activity was seen with the ColE9 L359C-F412C and the ColE9 Y324C-L447C mutant proteins; however diamide had no effect on the activity of ColE9. The presence of a disulfide bond was confirmed in both of the oxidized, mutant proteins by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The loss of biological activity of the disulfide-containing mutant proteins was not due to an indirect effect on the properties of the translocation or DNase domains of the mutant colicins. The data are consistent with a requirement for the flexibility of the coiled-coil R domain after binding to BtuB
Bird Movement Predicts Buggy Creek Virus Infection in Insect Vectors
Predicting the spatial foci of zoonotic diseases is a major challenge for epidemiologists and disease ecologists. Migratory birds are often thought to be responsible for introducing some aviozoonotic pathogens such as West Nile and avian influenza viruses to a local area, but most information on how bird movement correlates with virus prevalence is anecdotal or indirect. We report that the prevalence of Buggy Creek virus (BCRV) infection in cimicid swallow bugs (Oeciacus vicarius), the principal invertebrate vector for this virus, was directly associated with the likelihood of movement by cliff swallows (Petrochelidon pyrrhonota), an amplifying host for the virus, between nesting colonies. The prevalence of BCRV in bugs was also directly correlated with the number of swallows immigrating into a site. Birds that move into a site are often transient individuals that may have more often encountered virus elsewhere. These results indicate that the magnitude and direction of daily bird movement in a local area can accurately predict transmission foci for this virus and provide rare quantitative evidence that birds can play a critical role in the dispersal of certain vector-borne viruses
Bird Movement Predicts Buggy Creek Virus Infection in Insect Vectors
Predicting the spatial foci of zoonotic diseases is a major challenge for epidemiologists and disease ecologists. Migratory birds are often thought to be responsible for introducing some aviozoonotic pathogens such as West Nile and avian influenza viruses to a local area, but most information on how bird movement correlates with virus prevalence is anecdotal or indirect. We report that the prevalence of Buggy Creek virus (BCRV) infection in cimicid swallow bugs (Oeciacus vicarius), the principal invertebrate vector for this virus, was directly associated with the likelihood of movement by cliff swallows (Petrochelidon pyrrhonota), an amplifying host for the virus, between nesting colonies. The prevalence of BCRV in bugs was also directly correlated with the number of swallows immigrating into a site. Birds that move into a site are often transient individuals that may have more often encountered virus elsewhere. These results indicate that the magnitude and direction of daily bird movement in a local area can accurately predict transmission foci for this virus and provide rare quantitative evidence that birds can play a critical role in the dispersal of certain vector-borne viruses
Exceptional sperm cooperation in the wood mouse
Spermatozoa from a single male will compete for fertilization of ova with spermatozoa from another male when present in the female reproductive tract at the same time. Close genetic relatedness predisposes individuals towards altruism, and as haploid germ cells of an ejaculate will have genotypic similarity of 50%, it is predicted that spermatozoa may display cooperation and altruism to gain an advantage when inter-male sperm competition is intense. We report here the probable altruistic behaviour of spermatozoa in an eutherian mammal. Spermatozoa of the common wood mouse, Apodemus sylvaticus, displayed a unique morphological transformation resulting in cooperation in distinctive aggregations or 'trains' of hundreds or thousands of cells, which significantly increased sperm progressive motility. Eventual dispersal of sperm trains was associated with most of the spermatozoa undergoing a premature acrosome reaction. Cells undergoing an acrosome reaction in aggregations remote from the egg are altruistic in that they help sperm transport to the egg but compromise their own fertilizing ability
Obesity alters the muscle protein synthetic response to nutrition and exercise
Improving the health of skeletal muscle is an important component of obesity treatment. Apart from allowing for physical activity, skeletal muscle tissue is fundamental for the regulation of postprandial macronutrient metabolism, a time period that represents when metabolic derangements are most often observed in adults with obesity. In order for skeletal muscle to retain its capacity for physical activity and macronutrient metabolism, its protein quantity and composition must be maintained through the efficient degradation and resynthesis for proper tissue homeostasis. Life-style behaviors such as increasing physical activity and higher protein diets are front-line treatment strategies to enhance muscle protein remodeling by primarily stimulating protein synthesis rates. However, the muscle of individuals with obesity appears to be resistant to the anabolic action of targeted exercise regimes and protein ingestion when compared to normal-weight adults. This indicates impaired muscle protein remodeling in response to the main anabolic stimuli to human skeletal muscle tissue is contributing to poor muscle health with obesity. Deranged anabolic signaling related to insulin resistance, lipid accumulation, and/or systemic/muscle inflammation are likely at the root of the anabolic resistance of muscle protein synthesis rates with obesity. The purpose of this review is to discuss the impact of protein ingestion and exercise on muscle protein remodeling in people with obesity, and the potential mechanisms underlining anabolic resistance of their muscle
Cenozoic Uplift of south Western Australia as constrained by river profiles
The relative tectonic quiescence of the Australian continent during the
Cenozoic makes it an excellent natural laboratory to study recent large-scale
variations in surface topography, and processes that influence changes in its
elevation. Embedded within this topography is a fluvial network that is
sensitive to variations in horizontal and vertical motions. The notion that a
river acts as a 'tape recorder' for vertical perturbations suggests that
changes in spatial and temporal characteristics of surface uplift can be
deduced through the analysis of longitudinal river profiles. We analyse 20
longitudinal river profiles around the Australian continent. Concave upward
profiles in northeast Australia indicate an absence of recent surface uplift.
In contrast, the major knickzones within longitudinal profiles of rivers in
southwest Australia suggest recent surface uplift. Given the lack of recent
large-scale tectonic activity in that region, this uplift requires an
explanation. Applying an inverse algorithm to river profiles of south Western
Australia reveals that this surface uplift started in the Eocene and culminated
in the mid-late Neogene. The surface uplift rates deduced from this river
profile analysis generally agree with independent geological observations
including preserved shallow-marine sediment outcrops across the Eucla Basin and
south Western Australia. We show that the interplay between global sea level
and long-wavelength dynamic topography associated with south Western
Australia's plate motion path over the remnants of an ancient Pacific slab is a
plausible mechanism driving this surface uplift.Comment: 33 pages including 7 figures. Published in Tectonophysics, please see
final manuscript ther
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