7,188 research outputs found
Effect of potash on renal profile of albino wistar rats
This study is intended to investigate the effect of Potash on renal function. Twenty four (24) Albino wistar rats with mean weight of 126.3±23.9g were used. They were subdivided into four groups -A, B, C and D (n=6 each); with A serving as control while B, C and D served as test groups. Group A received normal feed and water while B, C and D received 3.0g/kg, 6.0g/kg and 9.0g/kg of potash per body weight for 21 days respectively. At the end of the experiment, the animals were sacrificed under light anesthesia to obtain blood samples for the estimation of renal function parameters. Sodium, Potassium, Chloride, Urea, Uric acid and Creatinine was analyzedusing standard analytical chemical methods. The results showed a significant (P<0.05) reduction in body weight and serum levels of sodium, potassium, chloride, urea and creatinine among the test groups. Serum levels of uric acid in the test groups were not significantly different (P>0.05) from that of the control. Our findings therefore, suggest that potash may have dosage dependent nephrotoxic and weight reduction potentials and by implication, may induce growth retardation. This indicates therefore, that potash is toxic to the kidney and there is need for further studies
Minimal set of generators of controllability space for singular linear dynamical systems
Due to the significant role played by singular systems in the form E ¿ x ( t ) = Ax ( t ) , on mathematical modeling of science and engineering problems; in the last years recent years its interest in the descriptive analysis of its structural and dynamic properties. However, much less effort has been devoted to studying the exact con- trollability by measuring the minimum set of controls needed to direct the entire system E ¿ x ( t ) = Ax ( t ) to any desired state. In this work, we focus the study on obtaining the set of all matrices B with a minimal number of columns, by making the singular system E ¿ x ( t ) = Ax ( t ) + Bu ( t ) controllable.Postprint (author's final draft
Automatic two-plane balancing for rigid rotors
Abstract We present an analysis of a two-plane automatic balancing device for rigid rotors. Ball bearings, which are free to travel around a race, are used to eliminate imbalance due to shaft eccentricity or misalignment. The rotating frame is used to derive autonomous equations of motion and the symmetry breaking bifurcations of this system are investigated. Stability diagrams in various parameter planes show the coexistence of a stable balanced state with other less desirable dynamics
Device asymmetries and the effect of the rotor run-up in a two-plane automatic ball balancing system
Compositionality, stochasticity and cooperativity in dynamic models of gene regulation
We present an approach for constructing dynamic models for the simulation of
gene regulatory networks from simple computational elements. Each element is
called a ``gene gate'' and defines an input/output-relationship corresponding
to the binding and production of transcription factors. The proposed reaction
kinetics of the gene gates can be mapped onto stochastic processes and the
standard ode-description. While the ode-approach requires fixing the system's
topology before its correct implementation, expressing them in stochastic
pi-calculus leads to a fully compositional scheme: network elements become
autonomous and only the input/output relationships fix their wiring. The
modularity of our approach allows to pass easily from a basic first-level
description to refined models which capture more details of the biological
system. As an illustrative application we present the stochastic repressilator,
an artificial cellular clock, which oscillates readily without any cooperative
effects.Comment: 15 pages, 8 figures. Accepted by the HFSP journal (13/09/07
Haloferax volcanii Proteome Response to Deletion of a Rhomboid Protease Gene
Rhomboids are conserved intramembrane
serine proteases involved
in cell signaling processes. Their role in prokaryotes is scarcely
known and remains to be investigated in <i>Archaea</i>.
We previously constructed a rhomboid homologue deletion mutant (Δ<i>rhoII</i>) in <i>Haloferax volcanii</i>, which showed
reduced motility, increased novobiocin sensitivity, and an N- glycosylation
defect. To address the impact of <i>rhoII</i> deletion on <i>H. volcanii</i> physiology, the proteomes of mutant and parental
strains were compared by shotgun proteomics. A total of 1847 proteins
were identified (45.8% of <i>H. volcanii</i> predicted proteome),
from which 103 differed in amount. Additionally, the mutant strain
evidenced 99 proteins with altered electrophoretic migration, which
suggested differential post-translational processing/modification.
Integral membrane proteins that evidenced variations in concentration,
electrophoretic migration, or semitryptic cleavage in the mutant were
considered as potential RhoII targets. These included a PrsW protease
homologue (which was less stable in the mutant strain), a predicted
halocyanin, and six integral membrane proteins potentially related
to the mutant glycosylation (S-layer glycoprotein, Agl15) and cell
adhesion/motility (flagellin1, HVO_1153, PilA1, and PibD) defects.
This study investigated for the first time the impact of a rhomboid
protease on the whole proteome of an organism
Interpreting and acting upon home blood pressure readings: A qualitative study
This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Vasileiou et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.Background: Recent guidelines recognize the importance of home blood pressure monitoring (HBPM) as an adjunct to clinical measurements. We explored how people who have purchased and use a home blood pressure (BP) monitor make sense of, and act upon, readings and how they communicate with their doctor about the practice of home monitoring.
Methods: A qualitative study was designed and participants were purposively recruited from several areas in England, UK. Semi-structured in-depth interviews were conducted with 18 users of home BP monitors. The transcribed data were thematically analysed.
Results: Interpretation of home BP readings is complex, and is often characterised by uncertainty. People seek to assess value normality using ‘rules of thumb’, and often aim to identify the potential causes of the readings. This is done by drawing on lay models of BP function and by contextualising the readings to personal circumstances. Based on the perceived causes of the problematic readings, actions are initiated, mostly relating to changes in daily routines. Contacting the doctor was more likely when the problematic readings persisted and could not be easily explained, or when participants did not succeed in regulating their BP through their other interventions. Most users had notified their doctor of the practice of home monitoring, but medical involvement varied, with some participants reporting disinterest or reservations by doctors.
Conclusions: Involvement from doctors can help people overcome difficulties and resolve uncertainties around the interpretation of home readings, and ensure that the rules of thumb are appropriate. Home monitoring can be used to strengthen the patient-clinician relationship
An efficient semiparametric maxima estimator of the extremal index
The extremal index , a measure of the degree of local dependence in
the extremes of a stationary process, plays an important role in extreme value
analyses. We estimate semiparametrically, using the relationship
between the distribution of block maxima and the marginal distribution of a
process to define a semiparametric model. We show that these semiparametric
estimators are simpler and substantially more efficient than their parametric
counterparts. We seek to improve efficiency further using maxima over sliding
blocks. A simulation study shows that the semiparametric estimators are
competitive with the leading estimators. An application to sea-surge heights
combines inferences about with a standard extreme value analysis of
block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal
publication. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10687-015-0221-
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