Simple Guidelines (simple + guideline)

Distribution by Scientific Domains


Selected Abstracts


Discriminant analysis as a tool to identify compounds with potential as transdermal enhancers

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2005
W. J. Pugh
Structure-activity relationships were sought for 73 enhancers of hydrocortisone permeation from propylene glycol across hairless mouse skin. Enhancers had chain lengths (CC) from 0 to 16 carbon atoms, 1 to 8 H-bonding atoms (HB), molecular weight 60 to 450, log P (calculated) ,1.7 to 9.7 and log S (calculated) ,7.8 to 0.7. These predictive properties were chosen because of their ready availability. Enhancement ratio (ER) was defined as hydrocortisone transferred after 24 h relative to control. Values for the ER ranged from 0.2 to 25.3. Multiple regression analysis failed to predict activity; ER values for the ,good' enhancers (ER>10) were underestimated. Simple guidelines suggested that high ER was associated with CC>12 and HB 2,5. This was refined by multivariate analysis to identify significant predictors. Discriminant analysis using CC, HB, and molecular weight correctly assigned 11 of the 12 ,good' enhancers (92%). The incorrectly assigned compound was a known, idiosyncratic Br compound. Seventeen of the 61 ,poor' enhancers (28%) were incorrectly assigned but four could be considered marginal (ER>8). The success of this simple approach in identifying potent enhancers suggested its potential in predicting novel enhancer activity. [source]


PHYLOGENETICALLY NESTED COMPARISONS FOR TESTING CORRELATES OF SPECIES RICHNESS: A SIMULATION STUDY OF CONTINUOUS VARIABLES

EVOLUTION, Issue 1 2003
NICK J. B. ISAAC
Abstract., Explaining the uneven distribution of species among lineages is one of the oldest questions in evolution. Proposed correlations between biological traits and species diversity are routinely tested by making comparisons between phylogenetic sister clades. Several recent studies have used nested sister-clade comparisons to test hypotheses linking continuously varying traits, such as body size, with diversity. Evaluating the findings of these studies is complicated because they differ in the index of species richness difference used, the way in which trait differences were treated, and the statistical tests employed. In this paper, we use simulations to compare the performance of four species richness indices, two choices about the branch lengths used to estimate trait values for internal nodes and two statistical tests under a range of models of clade growth and character evolution. All four indices returned appropriate Type I error rates when the assumptions of the method were met and when branch lengths were set proportional to time. Only two of the indices were robust to the different evolutionary models and to different choices of branch lengths and statistical tests. These robust indices had comparable power under one nonnull scenario. Regression through the origin was consistently more powerful than the t -test, and the choice of branch lengths exerts a strong effect on both the validity and power. In the light of our simulations, we re-evaluate the findings of those who have previously used nested comparisons in the context of species richness. We provide a set of simple guidelines to maximize the performance of phylogenetically nested comparisons in tests of putative correlates of species richness. [source]


Dynesthetic and Dentogenic Concept Revisited

JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 3 2002
WILLIAM S. JAMESON BS
ABSTRACT: The dynesthetic and dentogenic concept, when applied, provides a more natural, harmonious prosthesis, which not only is desired by patients, but also is a quality of care they deserve. Outstanding esthetics can be achieved by simple guidelines, using tooth molds specifically sculpted for males and females, arranging prosthetic teeth to correspond with personality and age and sculpting the matrix (visible denture base) with more natural contours. There is no reason for edentulous individuals to be provided with care of any less quality than that available with other procedures, such as crowns, bridges, veneers, or implant restorations. Providing this upscale product can be rewarding and satisfying to patient and operator alike. This concept produces superior results no matter what posterior occlusal scheme is employed but, in the opinion of the author, works best when used in conjunction with a noninterceptive linear occlusion approach (not to be confused with lingualized occlusion), which precludes anterior contact. CLINICAL SIGNIFICANCE: Dentogenics provides an approach to esthetics in prosthodontics that enables the dentist to create a restoration in harmony with the patient's objective personality. This concept considers gender, I age, and personality to restore the patient's dignity and unique individuality that has been missing in far too many prostheses. [source]


Structural design of composite nonlinear feedback control for linear systems with actuator constraint,

ASIAN JOURNAL OF CONTROL, Issue 5 2010
Weiyao Lan
Abstract The performance of the composite nonlinear feedback (CNF) control law relies on the selection of the linear feedback gain and the nonlinear function. However, it is a tough task to select an appropriate linear feedback gain and appropriate parameters of the nonlinear function because the general design procedure of CNF control just gives some simple guidelines for the selections. This paper proposes an operational design procedure based on the structural decomposition of the linear systems with input saturation. The linear feedback gain is constructed by two linear gains which are designed independently to stabilize the unstable zero dynamics part and the pure integration part of the system respectively. By investigating the influence of these two linear gains on transient performance, it is flexible and efficient to design a satisfactory linear feedback gain for the CNF control law. Moreover, the parameters of the nonlinear function are tuned automatically by solving a minimization problem. The proposed design procedure is illustrated by applying it to design a tracking control law for the inverted pendulum on a cart system. Copyright 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]


Thoracic aneurysm repair: Managing severe tortuosity with brachiofemoral traction

CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 7 2007
Christos Lioupis MD
Abstract Challenging anatomy of the thoracic aorta is often encountered, and aortic tortuosity may be a major impediment to the propulsion of the stent-graft. Traction on both ends of a guidewire, with one end exiting the right upper extremity and the other end exiting the lower extremity, is an excellent option to manage thoracic aorta tortuosity. Careful application of simple guidelines may lessen associated risks and improve safety. 2007 Wiley-Liss, Inc. [source]