Approach to Mental Retardation and Global Developmental Delay

ObjectiveMental Retardation (MR) or Intellectual Disability is one of three chronic and disabling neurological disorders of children and adolescents. Its prevalence is estimated 1-3% of the population. MR is defined as significant sub-average intellectual functioning and adaptive behavior that become detectable before the age of 18. MR may come into view before 5 years as delay in at least two developmental domains which is called Global Developmental Delay (GDD).The causes of mental retardation can be considered under the titles of prenatal, perinatal and postnatal factors. Prenatal causes account for approximately 60 -80 % of the etiological factors. All patients with GDD / MR should undergo a stepwise diagnostic approach, because a specific diagnosis leads to opportunity for treatment, future planning and genetic counseling. History, physical examination and neurodevelopmental examinations are the most important parts of the approach. Recent advances in cytogenetic investigations and neuroimaging studies have led to recognition of new disorders and improvement of the diagnostic yield.Keywords: Mental retardation ; global developmental delay; diagnostic yield

Modelling of energy requirements by a narrow tillage tool

The amount of energy consumed during a tillage operation depends on three categories of parameters: (1) soil parameters (2) tool parameters and (3) operating parameters. Although many research works have been reported on the effects of those parameters on tillage energy, the exact number of affecting parameters and the contribution of each parameter in total energy requirement have not been specified. A study with the objectives of specifying energy consuming components and determining the amount of each component for a vertical narrow tool, particularly at high speeds of operation, was conducted in the soil bin facilities of the Department of Agricultural and Bioresource Engineering, University of Saskatchewan. Based on studies by Blumel (1986) and Kushwaha and Linke (1996), four main energy consuming components were assumed: (1) energy requirements associated with soil-tool interactions;(2) energy requirements associated with interactions between tilled and fixed soil masses;(3) energy requirements associated with soil deformation; and (4) energy requirements associated with the acceleration of the tilled soil. Energy requirement of a vertical narrow tool was calculated based on the draft requirement of the tool measured in the soil bin. The effects of three variables, moisture content, operating depth and forward speed, were studied at different levels: (1) moisture content at 14% and 20%; (2) depth at 40, 80, 120 and 160 mm; and (3) speed at 1, 8, 16 and 24 km h-1. Total energy requirement was divided into these four components based upon the procedure developed in the research. Regression equations for different energy components were developed based on experimental data of two replicates and then validated by extra soil bin experiments conducted at same soil and tool but different operational conditions. The set up of energy components data in the model development showed good correlation with the available experimental data for all four components. Coefficients of all regression equations showed a first order energy-moisture content relationship best applicable to those equations of energy components. For the acceleration component, energy-depth relationship at all speed levels resulted in an equation which included first and second orders of depth. In contrast, if only two higher levels of speed were used in the regression model, the relationship between acceleration energy and depth resulted in the second order of depth. When experimental data of acceleration energy at 8, 16, and 24 km h-1 speeds were used in the regression equation, the acceleration energy-speed relationship resulted in both linear and quadratic relationships. It was concluded that for the tool and soil conditions used in the experiments, 8 km h-1 speed resulted in only linear relationship. On the other hand, 16 and 24 km h-1 speeds resulted in a quadratic relationship. Therefore, for all 3 speeds used in experiments, both linear and quadratic relationships were obtained. Considering that the tool was operating at high speeds, this research is expected to contribute valuable experimental data to the researchers working in the field of soil dynamics

The Full Non-Rigid Group Theory for cis- and trans-Dichlorodiammine Platinum(II) and Trimethylamine

The non-rigid molecule group theory (NRG), in which the dynamical symmetry operations are defined as physical operations, is a new field of chemistry. In a series of papers Smeyers applied this notion to determine the character table of restricted NRG (r-NRG) of some molecules. For example, Smeyers and Villa computed the r-NRG of the triple equivalent methyl rotation in pyramidal trimethylamine with inversion and proved that the r-NRG of this molecule is a group of order 648, containing two subgroups of order 324 without inversions (see J. Math. Chem. 28 (2000) 377–388). In this work, a simple method is described, by means of which it is possible to calculate character tables for the symmetry group of molecules consisting of a number of AH3 groups attached to a rigid framework. We have studied the full non-rigid group (f-NRG) of cis- and trans-dichlorodiammine platinum(II) and trimethylamine and we have proven that they are groups of orders 36, 72 and 1296 with 9, 18 and 28 conjugacy classes, respectively. This shows that the full non-rigid group and the restricted non-rigid group of these molecules are not isomorphic. The method can be generalized to apply to other non-rigid molecules. The f-NRG molecule group theory is shown to be used advantageously to study the internal dynamics of such molecules