Sensitivity and specificity of tympanometric gradient and middle ear resonance in young children and infants

This paper discusses the use of tympanometric gradient, middle ear resonance and static admittance as diagnostic tools for testing the hearing of children and infants.

Declines of Aerial Insectivores in North America Follow a Geographic Gradient

North American birds that feed on aerial insects are experiencing widespread population declines. An analysis of the North American Breeding Bird Survey trend estimates for 1966 to 2006 suggests that declines in this guild are significantly stronger than in passerines in general. The pattern of decline also shows a striking geographical gradient, with aerial insectivore declines becoming more prevalent towards the northeast of North America. Declines are also more acute in species that migrate long distances compared to those that migrate short distances. The declines become manifest, almost without exception, in the mid 1980s. The taxonomic breadth of these downward trends suggests that declines in aerial insectivore populations are linked to changes in populations of flying insects, and these changes might be indicative of underlying ecosystem changes.

The response of a uniform horizontal temperature gradient to heating

The response of a uniform horizontal temperature gradient to prescribed fixed heating is calculated in the context of an extended version of surface quasigeostrophic dynamics. It is found that for zero mean surface flow and weak cross-gradient structure the prescribed heating induces a mean temperature anomaly proportional to the spatial Hilbert transform of the heating. The interior potential vorticity generated by the heating enhances this surface response. The time-varying part is independent of the heating and satisfies the usual linearized surface quasigeostrophic dynamics. It is shown that the surface temperature tendency is a spatial Hilbert transform of the temperature anomaly itself. It then follows that the temperature anomaly is periodically modulated with a frequency proportional to the vertical wind shear. A strong local bound on wave energy is also found. Reanalysis diagnostics are presented that indicate consistency with key findings from this theory.

Determination of the impact of continuous defoliation of Lolium perenne and Trifolium repens on bacterial and fungal community structure in rhizosphere soil

To determine the effects of defoliation on microbial community structure, rhizosphere soil samples were taken pre-, and post-defoliation from the root tip and mature root regions of Trifolium repens L. and Lolium perenne L. Microbial DNA isolated from samples was used to generate polymerase chain reaction-denaturing gradient gel electrophoresis molecular profiles of bacterial and fungal communities. Bacterial plate counts were also obtained. Neither plant species nor defoliation affected the bacterial and fungal community structures in both the root tip and mature root regions, but there were significant differences in the bacterial and fungal community profiles between the two root regions for each plant. Prior to defoliation, there was no difference between plants for bacterial plate counts of soils from the root tip regions; however, counts were greater in the mature root region of L. perenne than T. repens. Bacterial plate counts for T. repens were higher in the root tip than the mature root region. After defoliation, there was no effect of plant type, position along the root or defoliation status on bacterial plate counts, although there were significant increases in bacterial plate counts with time. The results indicate that a general effect existed during maturation in the root regions of each plant, which had a greater impact on microbial community structure than either plant type or the effect of defoliation. In addition there were no generic consequences with regard to microbial populations in the rhizosphere as a response to plant defoliation.

Soil fertility management in the mid-hills of Nepal: Practices and perceptions

Sustaining soil fertility is essential to the prosperity of many households in the mid-hills of Nepal, but there are concerns that the breakdown of the traditional linkages between forest, livestock, and cropping systems is adversely affecting fertility. This study used triangulated data from surveys of households, discussion groups, and key informants in 16 wards in eastern and western Nepal to determine the existing practices for soil fertility management, the extent of such practices, and the perception of the direction of changes in soil fertility. The two principal practices for maintaining soil fertility were the application of farmyard manure (FYM) and of chemical fertilizer (mainly urea and diammonium phosphate). Green manuring, in-situ manuring, slicing terrace risers, and burning plant residues are rarely practiced. FYM usage was variable with more generally applied to khet land (average 6053 kg fresh weight manure ha(-1)) than to bari land (average 4185 kg fresh weight manure ha-1) with manure from goats and poultry preferred above that from cows and buffaloes. Almost all households (98%) apply urea to khet land and 87% to bari land, with 45% applying diammonium phosphate to both types of land. Application rates and timings of applications varied considerably both within and between wards suggesting poor knowledge transfer between the research and farming communities. The benefits of chemical fertilizers in terms of ease of application and transportation in comparison with FYM, were perceived to outweigh the widely reported detrimental hardening of soil associated with their continued usage. Among key informants, FYM applied in conjunction with chemical fertilizer was the most popular amendment, with FYM alone preferred more than chemical fertilizer alone - probably because of the latter's long-term detrimental effects. Key informant and householder surveys differed in their perception of fertility changes in the last decade probably because of differences in age and site-specific knowledge. All key informants felt that fertility had declined but among households, only about 40% perceived a decline with the remainder about evenly divided between no change and an increase. Householders with small landholdings (< 0.5 ha) were more likely to perceive increasing soil fertility while those with larger landholdings (> 2 ha) were more likely to perceive declining fertility. Perceived changes in soil fertility were not related to food self-sufficiency. The reasons for the slow spread of new technologies within wards and the poor understanding of optimal use of chemical fertilizers in conjunction with improved quality FYM may repay further investigation in terms of sustaining soil fertility in this region.

Projected gradient approach to the numerical solution of the SCoTLASS

The SCoTLASS problem-principal component analysis modified so that the components satisfy the Least Absolute Shrinkage and Selection Operator (LASSO) constraint-is reformulated as a dynamical system on the unit sphere. The LASSO inequality constraint is tackled by exterior penalty function. A globally convergent algorithm is developed based on the projected gradient approach. The algorithm is illustrated numerically and discussed on a well-known data set. (c) 2004 Elsevier B.V. All rights reserved.

Effects of biosolids from tomato processing on soil fertility and wheat growth in a Greek alfisol

The effects of biosolids from tomato processing on soil properties and wheat growth were investigated in an Alfisol from central Greece. Biosolids were mixed with soil from the surface (Ap) or subsurface (Bt) horizon in plastic containers at rates of 1%, 5%, and 10% by dry weight (d.w.; equivalent to 10, 50, and 100 Mg ha–1). Biosolid treatments were compared to an NH4Cl application (50 mg N kg–1) and an untreated control in (1) a 102 d incubation experiment at 28°C to determine biosolid nitrification potential and (2) a 45 d outdoor experiment to evaluate effects on soil fertility and wheat growth. Mineralization of biosolids in the incubation experiment resulted in accumulation of nitrate-N and indicated that biosolids were able to supply N that was in excess of crop needs in treatments of 5% and 10%. After 45 d of wheat growth, available soil nutrients (N, P) and P uptake by wheat were distinctly lower in the Bt than in the Ap horizon. However, soil pH, electrical conductivity, organic matter, total N, nitrate-N, extractable P, and exchangeable K increased with increasing rate of biosolid application in both soils. These were followed by corresponding increases in wheat nutrient uptake and biomass production, thus demonstrating the importance of this organic material for sustaining production in soils of low immediate fertility. Compared to the NH4Cl treatment (50 kg N ha–1 equivalent), biosolid application rates of 5% and 10% had higher available soil nutrients, similar or higher nutrient uptake and higher wheat biomass. But only an application of 10% biosolids provided sufficient N levels for wheat in the surface soil, and even higher applications were required for providing sufficient N and P in the Bt horizon.

Nutritional implications on the fertility of high yielding dairy cows

This paper reviews energy utilisation in high yielding Holsteins and draws attention to the competing forces within the cow for nutrients to support different physiological processes. These comprise; meeting obligatory maintenance costs, providing essential nutrients for milk synthesis, maintenance of satisfactory milk composition, regulation of body tissue metabolism and body condition score and the establishment of reproductive cyclity after calving, followed by a successful pregnancy. Interrelationships between nutritional state and the partition of nutrients to these competing forces is discussed, with emphasis on the fertility of high yielding multiparous cows, aiming to determine the origins of some of the abnormal cycles and compromised fertility noted in such cows. A further analysis with primaparous heifers is provided and finally a number of strategies are identified that could be undertaken, to improve nutritional state and the overall fertility of high yielding cows. It is concluded that development of improved nutritional strategies represents a more reliable means of improving the overall productivity, along with the fertility of high yielding cows, than an increased focus on genetic selection, where predictability of response has often been disappointing.

High temperature stress and spikelet fertility in rice (Oryza sativa L.)

In future climates, greater heat tolerance at anthesis will be required in rice. The effect of high temperature at anthesis on spikelet fertility was studied on IR64 (lowland indica) and Azucena (upland Japonica) at 29.6 degrees C (control), 33.7 degrees C, and 36.2 degrees C tissue temperatures. The objectives of the study were to: (i) determine the effect of temperature on flowering pattern; (ii) examine the effect of time of day of spikelet anthesis relative to a high temperature episode on spikelet fertility; and (iii) study the interactions between duration of exposure and temperature on spikelet fertility. Plants were grown at 30/24 degrees C day/night temperature in a greenhouse and transferred to growth cabinets for the temperature treatments. Individual spikelets were marked with paint to relate fertility to the time of exposure to different temperatures and durations. In both genotypes the pattern of flowering was similar, and peak anthesis occurred between 10.30 h and 11.30 h at 29.2 degrees C, and about 45 min earlier at 36.2 degrees C. In IR64, high temperature increased the number of spikelets reaching anthesis, whereas in Azucena numbers were reduced. In both genotypes :511 h exposure to >= 33.7 degrees C at anthesis caused sterility. In IR64, there was no interaction between temperature and duration of exposure, and spikelet fertility was reduced by about 7% per degrees C > 29.6 degrees C. In Azucena there was a significant interaction and spikelet fertility was reduced by 2.4% degrees Cd-1 above a threshold of 33 degrees C. Marking individual spikelets is an effective method to phenotype genotypes and lines for heat tolerance that removes any apparent tolerance due to temporal escape.

Genetic parameters and evaluations from single- and multiple-trait analysis of dairy cow fertility and milk production

Genetic parameters and breeding values for dairy cow fertility were estimated from 62 443 lactation records. Two-trait analysis of fertility and milk yield was investigated as a method to estimate fertility breeding values when culling or selection based on milk yield in early lactation determines presence or absence of fertility observations in later lactations. Fertility traits were calving interval, intervals from calving to first service, calving to conception and first to last service, conception success to first service and number of services per conception. Milk production traits were 305-day milk, fat and protein yield. For fertility traits, range of estimates of heritability (h(2)) was 0.012 to 0.028 and of permanent environmental variance (c(2)) was 0.016 to 0.032. Genetic correlations (r(g)) among fertility traits were generally high ( > 0.70). Genetic correlations of fertility with milk production traits were unfavourable (range -0.11 to 0.46). Single and two-trait analyses of fertility were compared using the same data set. The estimates of h(2) and c(2) were similar for two types of analyses. However, there were differences between estimated breeding values and rankings for the same trait from single versus multi-trait analyses. The range for rank correlation was 0.69-0.83 for all animals in the pedigree and 0.89-0.96 for sires with more than 25 daughters. As single-trait method is biased due to selection on milk yield, a multi-trait evaluation of fertility with milk yield is recommended. (C) 2002 Elsevier Science B.V. All rights reserved.