Extent Of Clumping Research Articles

Comparison of weighted and unweighted methods of wealth indices for assessing SOCIO-ECONOMIC status

Due to some of the limitations of monetary measures, various non-monetary approaches for assessing household wealth have been developed as alternative tools for classifying household socio-economic status. Among them, wealth indices based on household durable assets are being used. The literature revealed that two basic methods of constructing wealth indices are employed: an unweighted method, where assets are weighted equally; and a weighted method, where specific weights are assigned to assets. In the case of using the weighted method, weighting can be assigned using various techniques. The overall objective of the study is to compare the wealth indices constructed by using weighted and unweighted methods for assessing the socio-economic status of households in rural Bangladesh. Firstly, the study attempts to construct wealth indices based on durable assets using the unweighted method and two techniques of the weighted method: weighted index using the inverse of proportion, and weighted index using principal component analysis (PCA). Following this, the study compares some distributional characteristics of these indices as well as monetary indicators. At the same time, the study evaluates and examines some attractive properties of these indices such as the extent of clumping and truncation, consistency with traditional monetary measures. Comparative analysis revealed that the unweighted asset index, as well as weighted asset index using PCA, can be treated as an efficient alternative to the monetary measures to evaluate the living standard of the households in the present study. However, due to some advantage's asset index using PCA can be considered to be somewhat better than the unweighted index. But, as the unweighted asset index is not very different from the weighted asset index using PCA, it can also be used as an alternative to the monetary measures without the need to use weighting.

Self-reinnervated cat medial gastrocnemius muscles. II. analysis of the mechanisms and significance of fiber type grouping in reinnervated muscles.

1. The technique of glycogen depletion was used to determine whether regenerating motor axons reestablish the normal regionalization of motor units (MUs) in the cat medial gastrocnemius (MG) muscle, 2) whether the extent of clumping between MU fibers and/or type grouping of muscle fibers progressively increases with a decrease in reinnervated MU numbers, and 3) whether the pattern of innervation can explain why MUs fail to increase significantly in size when the cut nerve is sutured directly to the muscle, even when few axons make functional connections. 2. Distributions of MU fibers were analyzed in 5 normal and 14 reinnervated cat MG muscles 4.5-16 mo after sectioning of its nerve and suturing of the proximal end to the distal nerve sheaths (N-N suture) or directly to the muscle fascia (N-M suture). Muscle unit distributions were quantified according to location, territory size, density, and extent of clumping between fibers from the same MU. 3. Normal MU fibers were regionalized within five regions along the muscle's longitudinal and transverse axes. Reinnervated MUs were located within similar regions, indicating that regenerating axons follow the major proximal nerve branches to restore normal compartmentalization. 4. Muscle unit fibers were diffusely scattered within discrete MU territories in normal muscles. Territory size tended to increase with MU size, whereas density of muscle unit fibers within the territory decreased. 5. Territories increased with MU size after N-N suture but were smaller and showed little size variation after N-M suture. The extent of muscle unit fiber clumping was inversely related to the number of reinnervated MUs. On average, the extent of clumping was substantially higher in muscles reinnervated after N-M suture. These results indicate that distal nerve sheaths facilitate proximal axon branching, which establishes MU territory size. Once the territory is established, motor axons branch distally to increase MU size, which in turn compensates for reduced MU numbers. 6. Muscles reinnervated by < 80% of the MUs exhibited fiber type grouping of type I fibers, and on average the extent of clumping was substantially higher in muscles reinnervated after N-M suture. With less innervation, type grouping increased inversely with the number of reinnervated MUs. However, for a similar number of MUs, type I fiber type grouping was substantially higher in muscle reinnervated after N-M suture. Type grouping therefore reflects muscle unit fiber clumping under conditions where MU size increased (N-N suture) or MU territory size decreased (N-M suture).

Structure and mechanisms of schooling intadpoles of the clawed frog, Xenopus laevis

The geometric structure and sensory bases of social aggregates in larvae of the clawed frog, Xenopus laevis, were studied using photographic data interpreted with the aid of a computerized image analyser. The system records positional data from photographs and uses this information to assess: (1) extent of parallel orientation between tadpoles that are nearest neighbours, (ii) distance over which significant parallel orientation is maintained (interactive distance), and (iii) extent of clumping or evenness of individuals. o (1) Under all density, size, and illumination conditions, tadpoles show a highly significant tendency to line up parallel (0° between neighbours) and, to a lesser extent, antiparallel (180° between neigh-bours) to their nearest neighbour. (2) Tadpoles in the light show a much greater tendency to orient parallel to nearest neighbours than in the dark. (3) The tendency to orient parallel to nearest neighbours increases slightly with increasing tadpole size and density. (4) In the light, tadpoles have an interactive distance of approximately two body lengths; in the dark, only approximately one body length. (5) Interactive distance shows a slight increase with decreasing tadpole density. (6) Interactive distance is proportional to tadpole size. (7) Spacing between tadpoles is random, but there is a weak tendency toward increased evenness with increasing tadpole size and density; tadpoles in the light position themselves more evenly than in the dark. We propose that Xenopus tadpoles use both visual and lateral line input to school. Lateral line input is presumably necessary for maintaining some degree of parallel orientation in the dark and is augmented by visual information in the light.

On the Clumping of Corynebacterium xerosis as Affected by Temperature

SUMMARY: Corynebacterium xerosis Strain NCIB 9956 (minimum temperature for growth about 20°) formed clumps in cultures or suspensions of bacteria from these cultures, when grown at 30° and rapidly cooled to 15° with fast stirring. Electron microscopy showed whole organisms to be connected by an adhesive material. Electron micrographs of thin sections showed that clumps appeared to be formed by single layers of bacteria collecting round gas bubbles. The extent of clumping was greatest around pH 3, and increased as the temperature was decreased from 30° to 15°. Substitution of nitrogen or oxygen for air as gas phase had little effect on the clumping. The clumping ability increased with the age of the culture from the mid-exponential to the late-exponential phase of growth, but thereafter declined. Salts were necessary for clump formation. The relative effects of different monovalent cations and anions depended on the positions of the ions in the Hofmeister series. Incubation of bacteria in buffered solutions of proteolytic enzymes decreased their clumping ability. The extent of clumping also decreased when bacteria were incubated in buffered solutions of guanidine HCl (5 M), urea (8 M) or in a solution of uranyl nitrate (10 mM) and NaCl (0.1 M). Isolated walls of the organism formed clumps when suspensions in phosphate buffer (pH 7.0) were incubated at temperatures between 35° and 5° with fast stirring. Pretreatment of walls with trypsin decreased clumping ability. The ability to form clumps when cultures were cooled to 5° with fast stirring was demonstrated with several but not all of the strains of C. xerosis tested.