Flexible covariance estimation in graphical Gaussian models

In this paper, we propose a class of Bayes estimators for the covariance matrix of graphical Gaussian models Markov with respect to a decomposable graph $G$. Working with the $W_{P_G}$ family defined by Letac and Massam [Ann. Statist. 35 (2007) 1278--1323] we derive closed-form expressions for Bayes estimators under the entropy and squared-error losses. The $W_{P_G}$ family includes the classical inverse of the hyper inverse Wishart but has many more shape parameters, thus allowing for flexibility in differentially shrinking various parts of the covariance matrix. Moreover, using this family avoids recourse to MCMC, often infeasible in high-dimensional problems. We illustrate the performance of our estimators through a collection of numerical examples where we explore frequentist risk properties and the efficacy of graphs in the estimation of high-dimensional covariance structures.Comment: Published in at http://dx.doi.org/10.1214/08-AOS619 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

FDM preparation of bio-compatible UHMWPE polymer for artificial implant

Due to its properties of high wear, creep resistance, high stiffness and strength, Ultra-High Molecular Weight Polyethylene (UHMWPE) was developed to eliminate most metallic wear in artificial implant, which conventionally found in stainless steel, Cobalt Chromium (Co-Cr) and Titanium (Ti) alloys. UHMWPE has an ultra-high viscosity that renders continuous melt-state processes including one of the additive manufacturing processes, Fused Deposition Modeling (FDM) ineffective for making UHMWPE implant. Attempt to overcome this problem and adapting this material to FDM is by blending UHMWPE with other polyethylene including High Density Polyethylene (HDPE) and Polyethylene-Glycol (PEG) which provide adequate mechanical properties for biomedical application along with the improvement in extrudability. It was demonstrated that the inclusion of 60% HDPE fraction has improved the flowability of UHMWPE in MFI test and showing adequate thermal stability in TGA

Importance of Technological Innovation for SME Growth: Evidence from India

This paper probes the drivers, dimensions, achievements, and outcomes of technological innovations carried out by SMEs in the auto components, electronics, and machine tool sectors of Bangalore in India. Further, it ascertains the growth rates of innovative SMEs vis-à-vis non-innovative SMEs in terms of sales turnover, employment, and investment. Thereafter, it probes the relationship between innovation and growth of SMEs by (i) estimating a correlation between innovation sales and sales growth, (ii) calculating innovation sales for high, medium, and low growth innovative SMEs and doing a aggregate one-way ANOVA, and (iii) ascertaining the influence of innovation sales, along with investment growth and employment growth on gross value-added growth by means of multiple regression analysis. The paper brings out substantial evidence to argue that innovations of SMEs contributed to their growth.Technological innovations, sales growth, auto components, electronics, machine tools, Bangalore

The transient response of global-mean precipitation to increasing carbon dioxide levels

The transient response of global-mean precipitation to an increase in atmospheric carbon dioxide levels of 1% yr(-1) is investigated in 13 fully coupled atmosphere-ocean general circulation models (AOGCMs) and compared to a period of stabilization. During the period of stabilization, when carbon dioxide levels are held constant at twice their unperturbed level and the climate left to warm, precipitation increases at a rate of similar to 2.4% per unit of global-mean surface-air-temperature change in the AOGCMs. However, when carbon dioxide levels are increasing, precipitation increases at a smaller rate of similar to 1.5% per unit of global-mean surface-air-temperature change. This difference can be understood by decomposing the precipitation response into an increase from the response to the global surface-temperature increase (and the climate feedbacks it induces), and a fast atmospheric response to the carbon dioxide radiative forcing that acts to decrease precipitation. According to the multi-model mean, stabilizing atmospheric levels of carbon dioxide would lead to a greater rate of precipitation change per unit of global surface-temperature change

Analysis of nutritive contents of some Nigerian fruits

Fruits are one of the oldest forms of food known to man and they present an important part of human diet in almost any culture of the world due to their high nutrients content. This study was undertaken to analyze the nutritive, minerals and energy values of some fruits such as banana (Musa esculentum), paw-paw(Carica papaya), pineapple (Ananas comosus), African mango (Irvigna gabonensis) and Avocado pear (Persia americana) that are consumed in Nigeria. The proximate composition of fruits shows that paw-paw has the highest moisture content (90.0±1.0%) while African mango has the highest ash content (13.06±1.0%). Similarly, the highest crude protein, lipid and fiber contents were recorded by avocado pea (10.0±0.2%, 2.85±0.7 and 15.81±1.0% respectively). The highest available carbohydrate content was observed in pineapple (82.57±0.8%) whereas; the highest energy values were recorded by paw-paw and pineapple (355.94±1.6 and 355.94±1.4 respectively). The results of the mineral analysis showed that Ca content was very low in all studied samples. However, appreciable amounts of K, Mg, Na and P were observed. Highest concentration of K was observed in the pulp of pineapple (436.1±4.8mg/100g) while banana pulp recorded highest amounts of Mg (81.7±1.4mg/100g). Moreover, the Na content was found to be highest in husk of avocado pear (7.3±0.7mg/100g) while the peel of banana has the highest content of P (49.0±0.5mg/100g). Comparing values of mineral elements obtained in this study with the recommended daily allowance (RDA), only K, Mg and P levels could possibly meet the stipulated requirements in these fruits. Meanwhile, the presence of mineral elements in the husks of these fruits indicates that they could be used as source of minerals in the formulation of animal feed.Keywords: Fruits, Pulp, Husk, Proximate, Mineral elements, RD

Effects of Striga gesnerioides on the Growth and Yield of Some Cowpea (Vigna unguiculata (L.) Walp) Genotypes under Water Stress Condition

Cowpea production in the Sahelian region faced production constraint due to disease and drought. Striga gesnerioides is a major constraint to cowpea production specifically to the agronomic point of view. The aim of this present study is to determine the effect of Striga gesnerioides on the growth and yield of some cowpea genotypes subjected to different moisture stress conditions. The experiment was conducted at screen house of the International Institute of Tropical Agriculture (IITA) Kano, Nigeria. Three cowpea varieties were used in the experiment, the experimental set up was completely randomized design with four treatment regimes; T1, vegetative stage of water stress with Striga infestation; T2, vegetative stage of water stress; T3, unstressed with Striga infestation and T4, unstressed. Uniform broadcasting of 0.05g of Striga gesnerioides were imposed in the treatment. Data were collected on plant height, number of leaves, plant vigor score, phenology, and grain yield. The results showed that there is a significant difference in the number of leaves between the treatments with DANILA having the highest number of leaves. DANILA was found to exhibit the highest plant vigor. Total chlorophyll reductions were recorded at 37 days after water stress and striga infestation.DANILA recorded the highest reduction in total chlorophyll content. The results showed that IT98K-205-8 matured earlier and recorded higher yield, Danilarecorded low yield. It can be concluded that cowpea varieties IT97K-499-35 and IT98K-205-8 which gave the highest yield were resistance to Striga gesnerioides, whereas Danila which developed Symptoms with reduced yield is said to be susceptible to Striga gesnerioides.Keyword: Striga gesnerioides, cowpea, water stres