Unimodal Type Research Articles

Models of tracer breakthrough and permeability in simple fractured porous media

Abstract Tailing and bimodal behaviour of tracer breakthrough curves from tracer tests conducted in fractured porous media are commonly presented as ‘deviations’ from the Fickian model for homogeneous porous media. Tailing is mainly attributed to: (1) tracer storage brought about by diffusion between mobile and static regions of fluid; (2) a concentration of flow towards the wider (aperture) and, thus, more permeable fracture zones; and (3) the high variance in fracture conductivity and consequent mixing of tracer. Bi- (or multi-) modality has been attributed to solute following a few highly permeable flow paths. Systematic numerical simulations of flow and transport in geometrically simple fractured porous media were conducted using a 2D finite difference flow code and a particle tracking transport model. As a simplification only advective dispersion was considered. The modelling study produced a large variety of tracer breakthrough curves, including two patterns commonly seen in field data — the backward tailed uni-modal type and the Gaussian type. The study demonstrates that different types of breakthrough might be characteristic of particular sets of conceptual models for heterogeneities and, as such, may provide a useful pointer in the application and interpretation of tracer tests.

Morphometric analysis of the human trigeminal nerve.

We evaluated the components of nerve fibers of the motor and sensory roots of the trigeminal nerve by morphometric analysis. Trigeminal nerves were obtained from 5 cadavers (males, aged 67-95) were stained by Masson-Goldner-Goto method and examined under the microscope using a morphometric image-analyzer. The area and perimeter of axons were larger in the motor root than in the sensory root. The size distribution of axons was wider in the motor root than in the sensory root and the distribution pattern was unimodal type. These findings suggested that nerve fibers of the human trigeminal nerve gave similar findings to those of other peripheral nerves, regarding axonal size distribution and relative size of motor and sensory nerve axons.

Leaf dynamics and shoot phenology of eleven warm-temperate evergreen broad-leaved trees near their northern limit in central Japan

Dynamic features of shoot phenology including leaf emergence and leaf fall, and leaf life span for eleven evergreen broad-leaved tree species were investigated in a warm-temperate rain forest in Mount Kiyosumi, central Japan. All species had periodic leaf emergence or flushing pattern, and were classified into two types; single and multiple flush and only one species, Eurya japonica, represented the latter type and the rest had single flush in spring. The single flush type can further be subdivided into two groups according to their duration of shoot growth; short and long flush. Seasonal patterns of leaf fall were categorized into four; unimodal, bimodal, broad unimodal, and multimodal type though they were not fixed pattern. The leaf emergence and leaf fall patterns were correlated for the eleven species, and five phenological types were categorized. Four of them were the single flush types, i.e., short flush of leaf emergence with unimodal leaffall (SSU) type of Castanopsis sieboldii and Quercus salicina, short flush with bimodal leaf fall (SSB) type of Quercus acuta, Machilus thunbergii, Neolitsea sericea, and Cinnamomum japonicum, long flush with bimodal leaffall (SLB) type of Myrsine seguinii, and long flush with broad unimodal leaffall (SLR) type of Symplocos prunifolia, Cleyera japonica, and Illicium anisatum. The multiple flush type is only one species, Eurya japonica, and it had multimodal leaffall pattern (MM type). The phenological pattern varied in relation to leaf life span, leaf size, and tree habit. Leaf life span ranged from 1.1 to 5.8 yr. The short flush species or SSU and SSB types were all canopy or subcanopy trees, and the former had short and the latter had long leaf life spans. The long flush species were all microphyllous small trees, and SLB type had a relatively long leaf life span in understory, SLR type had a long leaf life span in understory or in open habitat and/or forest gap as a pioneer tree. MM type had a long leaf life span and colonizing species in open habitat but they can survive in understory as well. The phenological attributes of evergreen trees were well corresponded to the ecological guild of the tree in both forest structure and successional stage, and were also constrained by phylogenetic groups.

Effects of Planting Density on Growth and Distribution of Roots in Rice Plants (Oryza sativa L.).

水稲の根群形成ならびに地上部と地下部の相対生長に及ぼす栽植密度の影響について解析した. 栽植密度は3.3m2当たり45株, 70株, 95株および120株の4段階とした. その結果, (1) 栽植密度の増加に伴って, 水稲はT-R率を高め, 地上部に対する根の劣生長が助長された. (2) 単位面積当たりの根重は, 高密度(95, 120株)において最高分げつ期直後に最高値に達して, 単頂型の推移を示したのに対し, 低密度(45, 70株)区では, 最高分げつ期直後と出穂期に増大する2頂型の推移を示した. (3) 根群は栽植密度の増加に伴って, 土壌表層に分布する割合が高くなった. しかし, 高密度区の表層根は生育後期において根重の減少が著しかった. (4) 栽植密度の増加に伴って単位面積当たりの冠根数は増加したが, 冠根は細くなる傾向を示した.

Activity pattern ofCrotalus durissus(Viperidae, Crotalinae): Feeding, reproduction and snakebite

One hundred and seventy‐three adults and twenty‐six juveniles of Crotalus durissus were examined by removing the stomach contents and faecal material. Rattlesnakes were most active between April and May (autumn) (unimodal type), but most intensive feeding occurred during summer and autumn (February to May). Juveniles were observed to feed from late autumn (May) through the winter. Prey consisted of rodents (Cavia aperea, Rattus norvegicus and Mus sp.) and no ontogenetic change was observed in the diet. Feeding peaks precede vitellogenesis (autumn ‐ winter). Mated females continue feeding until ovulation (spring). It was observed that the biggest number of accidents were caused by snakes with stomach contents, especially males.

Mechanism of directional selectivity in simple neurons of the cat's visual cortex analyzed with stationary flash sequences.

The properties of simple neurons showing selectivity to direction of motion in area 17 of the cat cortex were examined. We analyzed in particular a sample of cells receiving a projection from 0 to 10 degrees in visual angle from the area centralis of the cat retina. Three categories of simple neurons were examined: directionally asymmetric (DA) neurons, directionally selective neurons of the unimodal type (DS1), and bimodal types (DS2). Poststimulus time histograms (PSTH) were obtained to moving white and black bars as well as to static onset sequences and static offset sequences. Our analysis involves a comparison of responses to single static flashes at various receptive-field locations with responses to sequence pairs of static flashes at those same locations. We find that DA neurons are not sensitive to the direction in which a pair of stimuli are presented. Inhibitory and excitatory responses show properties of linear summation whatever the direction of the stimulus sequence. Their behavior is reminiscent of retinal and LGN neurons. The synergy model accounts well for a DA neurons's directional asymmetry. If pairs of stimuli are close enough (usually an interstimulus distance of 20' or less for the central 10 degrees of the cat's visual field), then DS neurons show striking departures from linear summation. Specifically, this departure entails an anisotropic distribution of inhibition. The directional selectivity of DS neurons cannot be explained on the basis of a simple linear combination of their on and off region's responses. Directional selectivity is produced entirely within an on-excitatory discharge region or entirely within an off-excitatory discharge region. The excitatory discharge center of even the simplest unimodal DS neuron can be shown to be decomposable into subunits smaller than that discharge center. The fact that the spread of this anisotropy of inhibition is often much more restricted than the entire extent of the DS neuron's excitatory discharge center argues strongly that underlying subregions or modules are contributing their inputs to DS neurons. A DS neuron does not analyze motion as an isolated unit; to the contrary, it is probably embedded in a pool of mutually "cooperative" DS neurons. The basic module of directional analysis is responsive either to an on-on sequence or an off-off sequence but not to both. It is not selective to an on-off sequence. Therefore, unimodal DS neurons (DS1) are performing an analysis of single moving edges.(ABSTRACT TRUNCATED AT 400 WORDS)

Diurnal rhythm of changes in the number of DNA-synthesizing and mitotically-dividing jejunal epithelial cells after subdiaphragmatic vagotomy

Bilateral subdiaphragmatic vagotomy in rats led to an increase in proliferative activity of the jejunal epithelium 7 days after the operation without any accompanying change in the diurnal rhythm of cell division. Meanwhile, after vagotomy the phase structure of the rhythm of DNA synthesis was modified in the intestinal epithelial cells: from the normal unimodal type it became bimodal.

Commercially important medicinal and aromatic plants of Nepal and their distribution pattern and conservation measure along the elevation gradient of the Himalayas

This study aims to assess and evaluate the number of commercially important medicinal and aromatic plants (MAPs) found in the trade and explore their distribution pattern and conservation measures along the Himalayan elevation gradient of Nepal. The species data for this study are based on primary as well as secondary sources, where as elevation range data are based only on secondary sources. The number of MAPs species and number of conservation sites present in each 100 m elevation band is estimated by interpolation. The assessed numbers of commercial MAPs are assigned in to different life forms group to find the life form spectrum of commercial species. The number of MAPs species and conservation sites present in each 100 m elevation band are evaluated as a response variable where as elevation gradient is the predictor. The relationship between them is elucidated by scatter plot as well as generalised liner models.
 
 In this study, we have assessed 143 species as commercial MAPs. The variation of MAPs species is found related to elevation. The MAPs species richness increases with increasing the elevation up to 1000 m then decrease with further increasing the elevation thus unimodal type of pattern is observed. The maximum numbers of MAPs are found at 1000 m but maximum numbers of conservation sites are found above this elevation range. We did not find the significant pattern between conservation sites and MAPs species richness along the elevation gradient of the Himalayas. The conservation sites of Nepal are less concentrated where MAPs species diversity is rich. 
 
 Key words: Medicinal and aromatic plants, elevation gradient, species richness, generalised linear model 
 
 Banko Janakari Vol.16(1) 2006 pp3-13

A Statistical Study of Normal Male Adult Human Hypophysis.

Due to the uncertainty that still exists with reference to the involvement of particular parts of the hypophysis in certain diseases, and the general lack of quantitative data on the normal proportion of the different subdivisions of this organ, it seemed desirable to study by recognized statistical methods enough normal hypophyses to give standards which would be sufficiently accurate for evaluating abnormal proportions. Clinical and pathological literature contain numerous statements to the effect that one or more parts of the hypophysis are enlarged or are too small, etc., without the author knowing the range of normal variability. In many cases unwarranted clinical deductions are based on such statements. This condition can lead only to further confusion. The material used consisted of 111 carefully selected normal male hypophyses, 20 to 76 years of age, from cases of relatively sudden accidental death. After getting the fresh weight of the organ serial sections were made. Every 20th section was projected and the different parts of the gland outlined at a magnification of 20 diameters, in general. In certain cases pars intermedia was projected at a higher magnification (up to 100 diameters). The different portions of the outline were cut out and weighed. This gave the proportion that any particular part constitutes of the whole. The weight of the paper was always more than 100 times the weight of the corresponding part of the fresh organ. The method is more fully explained in a previous note. The routine method of obtaining the hypophysis at autopsy made it necessary to cut off and discard the stalk and as much of the surrounding connective tissue as possible. The frequency distribution of the weight of the whole gland, of the anterior lobe, and of the posterior lobe, is of the common fairly symmetrical unimodal type; while that of the epithelium of pars intermedia and of the colloid is greatly skewed in the positive direction, i. e., towards the small values.