Forage yield potential of Sudan grass-cowpea irrigated mixtures in central Sudan

     The study was conducted at the Gezira University Farm, Wad Medani, Sudan, during the winter of 1998 and autumn of 1999 to investigate the effects of nine cropping systems, two rates of nitrogen and two harvesting dates on the quantity and quality of the forage produced by Sudan grass-cowpea mixtures. In both seasons, Sudan grass in around two months from sowing while cowpea flowered in about one month. Black seeded Sudan grass variety (SG2) outperformed the light brown seeded Sudan grass variety (SGI). The autumn forage yields were higher than those of winter. Mixing increased the per plant growth parameters of both crops and across seasons. In winter, the fresh forage yield of pure cowpea and the highest yielding mixture (40 SG2 + 20 CP) were comparable (averaging 6.6 t/ha), while in autumn, the highest yielding crop mixture was 30 SG2 + 30 CP (19.01 t/ha) which is not siB1ificantly different from that of pure SG2 (19.08 t/ha). The land equivalent ratio (LER) values exceeded 1.00, in both seasons, showing a clear advantage of mixtures over monocultures. The addition of 44 kg N/ha significantly increased the growth parameters and forage yield of sole Sudan grass and its mixtures with cowpea but not that of pure cowpea. Harvesting at 60 days from sowing appreciably increased growth parameters, fresh forage yield and quality of forage produced by all seeding combinations. Mixing showed significant effects on crude protein percentage, crude fibre percentage, total crude protein and total crude fibre

Saliva sampling of alcoholic participants using three saliva collection methods

The potential of using saliva as a diagnostic fluid is well documented. The aim of this study was to assess the quality and quantity of saliva DNA of alcoholic and non-alcoholic participants using three saliva collection methods; DNA-SalTM (Oasis Diagnostics, USA), Oragene-DNA (DNA Genotek Inc, Ontario, Canada) and whole saliva collection method. Saliva DNA of non-alcoholic (n=30) and alcoholic participants (n=10) age between 25 and 35 years was assessed qualitatively and quantitatively using spectrophotometry. Saliva DNA quantity was the highest for all participants when using the DNA-Sal TM saliva collection kit (p<0.05). The use of a mechanical scraper provided only in the DNA-Sal TM kit may have contributed to the highest DNA yield for all participants. The quantity of saliva DNA when assessed using spectrophotometer was found to be significantly lower (p<0.05) for the alcoholic (16±3.57 ng/μL) than non-alcoholic participants (19.92±6.18 ng/μL). To determine the integrity of the DNA samples, PCR amplification of the Alcohol Dehydrogenase gene, ADH1B was carried out and the PCR was found to be successful. For all participants, the DNA quality of the saliva collected using the three saliva collection methods was found to be in the acceptable range considered as pure DNA. The DNA quality and quantity of saliva collected from the three saliva collection methods were considered suitable for research purposes

Muscle spindles provide servo-assistance to jaw-closing muscles for chewing hard foods

The fundamental pattern of chewing induced by the network of neurons called central pattern generator has been reported to be modified by the information arising from the various oro-facial sensory receptors including muscle spindles of jaw closing muscles. The cell bodies of primary afferent neurons from these muscle spindles lie in mesencephalic trigeminal nucleus (MTN) in the brainstem. The aim of the study was to understand whether muscle spindles from jaw-closing muscles play any role in hard food chewing. Single neuronal discharge of muscle spindle afferents was recorded from the MTN simultaneous with jaw-movement and electromyograpic (EMG) activities of the left masseter (jaw-closing) muscle during chewing soft and hard foods (apple and pellet) in awake rabbits. Ten consecutive chewing cycles were taken for analysis. Discharge of nineteen muscle spindles from seven rabbits was successfully recorded. Muscle-spindle discharge was significantly higher during the closing phase of jaw-movement for the hard food chewing than for the soft food. The jaw-closing muscle EMG activity was significantly higher during hard food chewing compared to soft food. The spindle discharge was higher when the masseter muscle activity was greater for chewing hard food. Significant positive (r=0.822, p=<0.001) correlation was found between the difference of muscle activity between apple and pellet and the difference of spindle discharge between apple and pellet. Above findings suggest that the increase of spindle discharge during hard food chewing may play a role for facilitating jaw-closing muscle activities and thereby provides servo-assistance to jaw-closing muscles to compensate the hardness of food

Influence of Salinity of Mixing Water Towards Physical and Mechanical Properties of High Strength Concrete

Dramatic population and economic growth result in increasing demand for concrete infrastructure, which leads to an increment of freshwater demand and a reduction of freshwater resources. however, freshwater is a finite resource, which means that freshwater will be used up someday in the future when freshwater demand keeps increasing while freshwater resources are limited. therefore, replacing freshwater with seawater in concrete blending seems potentially beneficial for maintaining the freshwater resources as well as advantageous alternatives to the construction work near the sea. there have been few experimental research on the effect of blending water salt content on the mechanical and physical characteristics of concrete, particularly high-strength concrete. therefore, a research study on the influence of salt concentration of blending water on the physical and mechanical properties of high-strength concrete is necessary. this study covered the blending water salinity, which varied from 17.5 g/l to 52.5 g/l and was determined on the physical and mechanical properties, including workability, density, compressive strength, and flexural strength. the test results indicate that the use of sea salt in blending water had a slight negative influence on both the workability and the density of high strength concrete. it also indicates that the use of sea salt in blending water had a positive influence on both the compressive strength and the flexural strength of high-strength concrete in an earlystage

Environmental zonation across the Australian arid region based on long-term vegetation dynamics

Zonation of landscapes is generally based on broad scale biophysical data, field surveys, imagery and expert knowledge. Such zonation represents a static view of the environment and does not reflect dynamics and function. Arid environments are however often highly dynamic, and spatial and temporal patterns may be expressed over long periods of time. These dynamics need to be understood for management. Our aim is to understand the dynamics and functional response of vegetation in the Australian arid zone, and use this to inform and potentially improve the currently employed stratification. Principal component analysis of 25 years of satellite imagery identified underlying factors influencing patterns of arid vegetation growth, and regions of similar long-term response. Dominant factors of variation were identified as the spatial distribution of total vegetation growth, seasonality of growth, magnitude of seasonal variability in growth, and regularity of variation in growth. Additional variation resulted from episodic vegetation growth of limited spatial extent and duration. Classes expressing these functional components were compared with the existing biogeographical regions, revealing agreement in some instances, and in other cases adding information previously not available. The study demonstrates a new approach to Australian landscape zonation that has potential for much wider application.E.F. Lawley, M.M. Lewis, B. Ostendor

Muscle spindles provide servo-assistance to jaw-closing muscles for chewing hard foods

The fundamental pattern of chewing induced by the network of neurons called central pattern generator has been reported to be modified by the information arising from the various oro-facial sensory receptors including muscle spindles of jaw closing muscles. The cell bodies of primary afferent neurons from these muscle spindles lie in mesencephalic trigeminal nucleus (MTN) in the brainstem. The aim of the study was to understand whether muscle spindles from jaw-closing muscles play any role in hard food chewing. Single neuronal discharge of muscle spindle afferents was recorded from the MTN simultaneous with jaw-movement and electromyograpic (EMG) activities of the left masseter (jaw-closing) muscle during chewing soft and hard foods (apple and pellet) in awake rabbits. Ten consecutive chewing cycles were taken for analysis. Discharge of nineteen muscle spindles from seven rabbits was successfully recorded. Muscle-spindle discharge was significantly higher during the closing phase of jaw-movement for the hard food chewing than for the soft food. The jaw-closing muscle EMG activity was significantly higher during hard food chewing compared to soft food. The spindle discharge was higher when the masseter muscle activity was greater for chewing hard food. Significant positive (r=0.822, p=<0.001) correlation was found between the difference of muscle activity between apple and pellet and the difference of spindle discharge between apple and pellet. Above findings suggest that the increase of spindle discharge during hard food chewing may play a role for facilitating jaw-closing muscle activities and thereby provides servo-assistance to jaw-closing muscles to compensate the hardness of food

Changes in cell density and morphology of selected cells of the ageing human dental pulp

OBJECTIVES: The aim of this study was to determine the changes in cell density and morphology of selected cells of the ageing human dental pulp. BACKGROUND: Changes in cell density and morphology of dental pulp cells over time may affect their capability to respond to tooth injury. MATERIALS AND METHODS: One hundred thirty-one extracted teeth were obtained from individuals between the ages of 6 and 80 years. The apical 1/3 of the root region was removed from all teeth prior to routine processing for producing histological slides. The histology slides were used to study the changes in cell density and morphology of selected pulp cells; odontoblasts, subodontoblasts and fibroblasts in the crown and root regions of the dental pulp. Student's t-test and one-way anova were used for statistical analyses. RESULTS: In all age groups, the cell density for all types of cells was found to be higher in the crown than in the root (p < 0.05). In general, the pulp cell density was found to decrease with age in both the crown and root regions. However, it was noted that the reduction of coronal odontoblasts occurred later in life (40-49 years) when compared to that of subodontoblasts or fibroblasts (30-39 years). CONCLUSIONS: The density of the coronal pulp cells reduces and these cells undergo morphological changes with ageing of individuals and this may affect the pulp's ability to resist tooth injury