Accuracy and precision in estimation of age of Norwegian Arctic polar bears (Ursus maritimus) using dental cementum layers from known-age individuals

Validation of age estimation from tooth cementum growth layers was conducted for 32 polar bears (Ursus maritimus) of known age, by two readers. Both readers correctly estimated age for 24% of the bears, and 50–53% were within the year of correct age. The age of young animals (age 1–8) was overestimated, while ages for bears over 8 years were underestimated. Comparison between the readings of the two readers indicated that the precision was low. Further, one of the readers reread tooth slides earlier prepared and read by another age estimation laboratory. There was a large discrepancy between these readings indicating a bias in the ages estimated. We conclude that age estimation of polar bears can be difficult, particularly in populations where individuals may forage throughout the year. As tooth growth layers may deposit differently for bears from different areas, and as different laboratories may read the same slides according to different criteria, an evaluation of the methods should be conducted for all populations, based on a significant number of tooth slides, with a broad age range, from animals of known age.     

Age determination of corvina reina (Cynoscion albus) in the Gulf of Nicoya, Costa Rica, based on examination and analysis of hyaline zones, morphology and microstructure of otoliths

This is the first age determination study for Cynoscion albus , a large tropical sciaenid, using otolith morphology and daily increment analysis. The practicality of both methods for age determination is illustrated by their consistent estimates of age and von Bertalanffy growth parameters. The daily increment analysis was used to validate the surface readings. An alternative, otolith morphometrics, is shown to hold promise for rapid prediction of fish age. Two multivariate linear regression models using gross otolith dimensions can estimate the age of C. albus to within 1 year. Growth parameter estimates are: from surface readings: L =127.5cm with K =0.12; from daily increment readings: L = 122.1 cm with K =0.17. Implications for the stock assessment of tropical fish using size instead of age are discussed.     

Explaining the Variation in Greenhouse Gas Emissions Between Households: Socioeconomic,Motivational, and Physical Factors

Consumption‐accounted greenhouse gas (GHG) emissions (GHGEs) vary considerably between households. Research originating from different traditions, including consumption research, urban planning, and environmental psychology, have studied different types of explanatory variables and provided different insights into this matter. This study integrates explanatory variables from different fields of research in the same empirical material, including socioeconomic variables (income, household size, sex, and age), motivational variables (proenvironmental attitudes and social norms), and physical variables (dwelling types and geographical distances). A survey was distributed to 2,500 Swedish households with a response rate of 40%. GHGEs were estimated for transport, residential energy, food, and other consumption, using data from both the survey and registers, such as odometer readings of cars and electricity consumption from utility providers. The results point toward the importance of explanatory variables that have to do with circumstances rather than motivations for proenvironmental behaviors. Net income was found to be the most important variable to explain GHGEs, followed by the physical variables, dwelling type, and the geographical distance index. The results also indicate that social norms around GHG‐intensive activities, for example, transport, may have a larger impact on a subject's emission level than proenvironmental attitudes.     

Field Trial of a Microcolony Method for Testing the Antibiotic Sensitivity of Bacteria

The sensitivity of bacteria to antibiotics may be measured by a rapid method in which the criterion of sensitivity is inhibition of microcolony formation on agar which contains antibiotic. As this method allows a report on the antibiotic sensitivity of a pathogenic bacterium four hours after the test is set up, a trial of the method was carried out in a diagnostic laboratory. Two thousand five hundred and four strains of fast-growing bacteria were tested against 10 antibiotics. The overall correlation rate between the four-hour microscopic readings and the subsequent overnight readings on the same cultures was 98.1%. Seven per cent of the microscopical readings attempted gave indeterminate results, and reports on these tests were withheld until the following day.The time spent in making microscopical readings was considered fully justified by the fact that results of a high proportion of antibiotic sensitivity tests were available one day earlier than is usual with established methods.     

Alcohol-Xylene Versus Dioxane in the Shrinkage of Tissue

A direct measure of tissue volume changes using fluid displacement was employed to compare the effects of the ethyl alcohol-xylene with the dioxane method of tissue processing. Pieces of mouse kidney, spleen, testis and liver were compared after fixation in 10% neutral formalin and during clearing, dehydration and paraffin infiltration. It was found that 24 hr after fixation there was a 25% increase in volume. There was a progressive shrinkage during dehydration and clearing with dioxane to the volume of the tissue before fixation and a subsequent shrinkage of about 20% during paraffin infiltration. With the ethyl alcoholxylene method, tissue volumes returned to initial levels during alcohol dehydration, and progressively shrank with xylene treatment and paraffin infiltration. The final degree of shrinkage was about the same with both methods. This was confirmed from microscopic analysis of tissue components. It is concluded that one cannot use gross tissue shrinkage as the only criterion for selecting one method of tissue processing over another.     

The climate of a Danish beech wood, Hestehaven, eastern Jutland

The wind profile in the IBP beech stand and the vertical temperature distribution in the same beech stand and in a neighbouring clearing were investigated. In addition the temperature and humidity conditions in the trunk space of the beech stand and in the clearing were compared. The precipitation components were investigated during two periods.
Because of the topography and the small extent of the wood the wind profile depends strongly on the wind direction. Maximum temperatures were found to occur in the upper part of the canopy during in-leaf periods. During leafless periods the temperature distribution indicates the presence of two distinct levels of energy exchange, Advection of airmasses from the adjoining bay strongly influences the climate of the wood. Because of the density of trees and the narrow fanshaped canopies, yearly throughfalls amount to 55–60% of the total precipitation, while stemflows amount to as much as 12%.     

Light environments within montane tropical rainforest,Mt Bellenden Ker,North Queensland

Irradiance and photosynthetic photon flux density (PPFD) at five sites within a montane tropical rainforest were compared to test for differences among characteristic environments within the same forest type. The five habitats investigated were a large clearing (800 m²). a small gap (150 m²), the lower canopy, and two shaded understorey sites. Daily average irradiance ranged from 32.3 W m^-2 in the heavily shaded understorey to over 400 W m^-2 in the large clearing. Similarly, daily average PPFD ranged from 10.2 to over 800 μmol m^-2 s^-1 at corresponding sites, respectively. Daily total irradiation in the understorey, small gap, and lower canopy were 7.9–8.8%, 11.8% and 11.5%, respectively, of irradiation in the large clearing. For daily total PPFD, relative values for the same sites were 1.3–3.8%, 6.0% and 10.3%, respectively. Comparisons of frequency distributions for irradiance showed that the only significant difference was between the large clearing and the four forest sites. Comparisons of frequency distributions for PPFD showed significant differences among all five sites. Median PPFDs were always above the range of known light compensation points for rainforest plants even in the heavily shaded understorey, and usually above the known light saturation levels of canopy members. These results indicate that the reduction in PPFD by cloud cover does not limit the rates of photosynthesis.     

Malachite green-INT (MINT) method for determining active bacteria in sewage.

A membrane filtration method was developed to determine the proportion of active (respiring) bacteria at various stages of sewage treatment. Samples were incubated in the presence of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) and, after fixation, passed through membrane filters. Filters were counterstained with malachite green and then were examined by bright-field microscopy. The contrast between bacteria and the filter background was greatly improved by drying and then clearing the filter before counterstaining. By this method, it was found that active bacterial fractions in raw sewage, settled sewage, and secondary effluent were 40, 29, and 58%, respectively, whereas the proportion of respiring bacteria in chlorinated secondary effluent was 6.1%. The active bacterial fraction of activated sludge was found to be 16%. The proposed method represents a significant improvement in speed and simplicity over existing methods for determining active bacteria in sewage.     

Assessment of skeletal age in short and tall children

Skeletal age assessment has been carried out on 843 children between the ages of 31 and 122 months, selected as the tallest 2.5%, shortest 2.5% and median 5% of the Child Health and Development Studies population. Skeletal age was read from a roentgenogram of the left hand and wrist individually for each of the 30 ossification centers with reference to the Greulich and Pyle Atlas, second edition. The readings were performed blind, by one observer and a 20% sample was read a second time blind to determine the replicability of the assessments. Duplicate readings were within two months of each other in mean bone age and almost always within nine months of each other for individual centers. Estimates of weighted mean bone age vary considerably with stature. Mean bone ages of Negro children tend to be higher than those of White children; those of Chinese and Japanese boys tend to be lower than those of White boys. Generally, similar differences were found with respect to the estimated mean ages of onset of ossification for the ulna, lunate, scaphoid, trapezium and trapezoid.     

Genetic analysis of the structure of predisposition to diabetes mellitus. IV. Population-genetics study of two types of diabetes mellitus with onset at age 20-40

It was found that age-specific morbidity risks of type I diabetes mellitus (DM I) increased from the age of 0-4 yrs (0.012-0.013%) to the age of 10-14 yrs (0.04-0.045%) and then slightly decreased to 0.02-0.03%, remaining at this level up to 40 yrs. The "cumulative" morbidity risk of DM I (population risk of development of DM I for each born individual, irrespective of family history) was found to be 0.2% for the age from 0-4 to 40 yrs. Assuming the age-specific morbidity risks of DM I after the age of 40 yrs to be the same as that at 40 yrs (0.02-0.03%), the "cumulative" morbidity risk for this type of DM from birth to 75 yrs old was estimated to be 0.36-0.44%. First incidences of DM II in the population were only observed in 20 yrs olds. The morbidity risk level for DM II at the age 20-24 yrs was found to be lower than that for DM I at this age. The risk was about the same level both for DM I and for DM II at the age 25-34 yrs, the morbidity risk levels for DM II after 35 yrs exceeding that for DM I. The "cumulative" risk of DM II by the age of 40 yrs was 0.1% for men and 0.15% for women. Analysis of familial data revealed statistically significant increase in recurrent morbidity risk in relatives only for the types of DM presented in probands.(ABSTRACT TRUNCATED AT 250 WORDS)     

INTERACTIONS BETWEEN CROWN STRUCTURE AND LIGHT ENVIRONMENT IN FIVE RAIN FOREST PIPER SPECIES

Measurements of light variation among leaves within crowns of five Piper species were compared with estimates of spatial variation in light within understory, forest edge, and clearing habitats to estimate the extent to which crown structure contributes to variation in leaf light environment. Daily photon flux density (PFD) varied greatly within and among crowns. Coefficients of variation for daily PFD among sensors within a single crown ranged from 26 to 79%. Within a single crown located in a clearing, the range in daily PFD among leaves was nearly as great as the range over the entire sample of plants. In the understory, localized sunfleck activity contributed to a high degree of spatial variation in instantaneous and total PFD among leaves within individual crowns. Much of the microsite variation in sunfleck activity, however, reflected environmental conditions within the understory habitat. Within an array of sensors placed next to Piper crowns in the understory, correlations were poor for light sensors spaced only 0.2 m apart, and only 8% of the variance in light readings was explained by measurements made 0.5 m away. In the clearing habitats, microsite heterogeneity among leaves was more strongly influenced by leaf positions within crowns and leaf angles than by spatial heterogeneity within the habitat.     

Use of Tunable, Pulsed Dye Laser for Quantitative Fluorescence in Syphilis Serology (FTA-ABS Test)

A pulsed dye laser was used as an excitation source in a fluorescent treponemal antibody absorption (FTA-ABS) test. A high precision in quantitative fluorescence was obtained with this high-power excitation source coupled to an electronic detection system and a storage oscilloscope by standardization of fluorescence evaluation and through elimination of human error. One 0.4-mus pulse exposure was sufficient to record fluorescence intensity data on the oscilloscope. Absence of fading of fluorescence after repeated excitation permitted multiple readings of the same microscope field. Almost 100% reproducible results were obtained for the FTA-ABS test with 40 samples. Electronic detection of fluorescence and the high sensitivity obtained with laser excitation raise doubts about the relative value of quantitative immunofluorescence in the FTA-ABS test.     

An analysis for paternal-age effect in Ohio's Down syndrome births, 1970-1980.

The purpose of this study was to analyze Down syndrome (DS) births during 1970-1980 in the State of Ohio for a paternal-age effect independent of maternal age. Birth certificates and chromosome analysis records were used to ascertain 1,244 white DS births, which by capture-recapture methodology were estimated to comprise two-thirds of all white DS births in Ohio for this period. The control data consisted of 1,667,210 white live births in Ohio during the same period. One method of statistical analysis was a case-control comparison, which for each single-year maternal age compares the mean paternal age for controls with each observed DS paternal age. No statistically significant paternal-age effect was found in nine of the 11 years. For two of the years, and for all years combined, the DS fathers were significantly younger than the fathers of controls. When the data were subdivided according to ascertainment, one subpopulation--those DS individuals obtained from birth certificates alone--also showed a statistically significant negative paternal-age effect. The Mantel-Haenszel test was also applied to these data. Assuming no paternal-age effect, a lower rate of DS births than expected was found at paternal ages greater than or equal to 40, but not at greater than or equal to 45, greater than or equal to 50, or greater than or equal to 55. These same methods were used to test for a maternal-age effect. In each of the 11 years and over all 11 years combined, a strong and statistically significant positive maternal-age effect was detected.     

Evaluation of a chromogenic chito-oligosaccharide analogue, p-nitrophenyl-β-D-N,N'-diacetylchitobiose, for the measurement of the chitinolytic activity of bacteria

Three methods of quantifying chitinase activity were compared. The activities of crude chitinases of 10 bacterial isolates from different environments were estimated in terms of (1) the release of p -nitrophenol from the chromogenic chito-oligosaccharide analogues, p -nitrophenyl-β-D- N,N' -diacetylchitobiose, p -nitrophenyl- N -acetyl-β-D-glucosamine and p -nitrophenyl-β-D- N,N',N" -triacetylchitotriose, (2) the release of reducing sugars from chitin and (3) the formation of clearing zones on chitin agar. When crude chitinase from Bacillus pabuli was used the hydrolysis of p -nitrophenyl-β-D- N,N' -diacetylchitobiose correlated well with the release of reducing sugars from chitin and the formation of clearing zones on chitin agar. However, when the activity of crude chitinases from the different bacterial isolates were compared no agreement was found between the hydrolysis of p -nitrophenyl-β-D- N,N' -diacetylchitobiose and the release of reducing sugars from chitin or the formation of clearing zones on chitin agar. It was concluded that the assay with chromogenic p -nitrophenyl chito-oligosaccharide analogues is not well suited for studies that compare the chitinase activity of different bacteria.     

No increase in chromosome aberrations in workers from an oil catalytic cracking plant.

A study of structural chromosome aberration frequencies in blood lymphocytes was performed in a group of 20 oil catalytic cracking unit workers and in 26 subjects belonging to the office staff of an oil refining plant, as well as in 35 matched controls. Subjects in the latter group were of the same sex (males) and similar age as the exposed group, and had similar smoking habits. Benzo[a]pyrene levels in workplace air samples were also determined. The cytogenetic analysis failed to show any differences between the exposed and control groups. A slight increase in benzo[a]pyrene level above the Cuban national standard of 1 ng/m3 was found during the air sample analysis in the oil catalytic cracking unit.     

Age-growth models for tilapia Oreochromis aureus (Perciformes, Cichlidae) of the Infiernillo reservoir, Mexico and reproductive behaviour

In presence of a decrease in the catch from Infiernillo reservoir, Michoacán-Guerrero, Mexico, age and growth of tilapia Oreochromis aureus (Steindachner 1864) were estimated, as indispensable attributes for fishery management. Evaluations included scales and opercular bones readings and length frequency analysis. The population structure was determined too. Due to the great variation of tilapia individual growth and with the objective to have reliable growth estimations, linearized, non-parametric and non-linear methods were used and their applicability discussed. Comparison of ages determined from these methods revealed that opercular bones readings had advantages over scales. Reproduction and competition for space and food were considered as responsible factors for ring-formation on tilapia hard structures. The non-linear method was considered the best for modelling populations highly variable, which is characteristic of tilapia and tropical fish with multiple spawns. The growth parameters estimated were Linfinity = 479 mm, K = 0.46/yr, t0 = -0.055 yr. The tilapia population in Infiernillo reservoir is dominated by juveniles less than 1.5 years old. The fishery activity is affecting the tilapia population growth because are caught when they have not yet spawned. Therefore, this fishery is in urgent need of regulation. Increasing the mesh size of the gill nets might contribute to protect the reproductive potential of the stock.     

Influence of dietary fiber on xylanolytic and cellulolytic bacteria of adult pigs

Xylanolytic and cellulolytic bacteria were enumerated over an 86-day period from fecal samples of 10 8-month-old gilts that were fed either a control or a 40% alfalfa meal (high-fiber) diet. Fecal samples were collected from all pigs on days 0, 3, 5, 12, 25, 37, 58, and 86. Overall, the numbers of xylanolytic bacteria producing greater than 5-mm-diameter zones of clearing on 0.24% xylan roll tube medium after 24 to 36 h of incubation were 1.6 X 10(8) and 4.2 X 10(8)/g (dry weight) of feces for the control pigs and those fed the high-fiber diet, respectively. After 1 week of incubation, a large number of smaller zones of clearing (1 to 2 mm) appeared. Besides Bacteroides succinogenes and Ruminococcus flavefaciens, which produced faint zones of clearing in xylan roll tubes, three strains which closely resembled B. ruminicola hydrolyzed and used xylan for growth. The overall numbers of cellulolytic bacteria producing zones of clearing in 0.5% agar roll tube medium were 0.36 X 10(8) and 4.1 X 10(8)/g for the control pigs and those fed the high-fiber diet, respectively. B. succinogenes was the predominant cellulolytic isolate from both groups of pigs, and R. flavefaciens was found in a ratio of approximately 1 to 15 with B. succinogenes. Degradation of xylan and cellulose, measured by in vitro dry matter disappearance after inoculation with fecal samples, was significantly greater for pigs fed the high-fiber diet than that for the controls. These data suggest that the number of fibrolytic microorganisms and their activity in the large intestine of the adult pig can be increased by feeding pigs high-alfalfa-fiber diets and that these organisms are similar to those found in the rumen.     

Influence of dietary fiber on xylanolytic and cellulolytic bacteria of adult pigs.

Xylanolytic and cellulolytic bacteria were enumerated over an 86-day period from fecal samples of 10 8-month-old gilts that were fed either a control or a 40% alfalfa meal (high-fiber) diet. Fecal samples were collected from all pigs on days 0, 3, 5, 12, 25, 37, 58, and 86. Overall, the numbers of xylanolytic bacteria producing greater than 5-mm-diameter zones of clearing on 0.24% xylan roll tube medium after 24 to 36 h of incubation were 1.6 X 10(8) and 4.2 X 10(8)/g (dry weight) of feces for the control pigs and those fed the high-fiber diet, respectively. After 1 week of incubation, a large number of smaller zones of clearing (1 to 2 mm) appeared. Besides Bacteroides succinogenes and Ruminococcus flavefaciens, which produced faint zones of clearing in xylan roll tubes, three strains which closely resembled B. ruminicola hydrolyzed and used xylan for growth. The overall numbers of cellulolytic bacteria producing zones of clearing in 0.5% agar roll tube medium were 0.36 X 10(8) and 4.1 X 10(8)/g for the control pigs and those fed the high-fiber diet, respectively. B. succinogenes was the predominant cellulolytic isolate from both groups of pigs, and R. flavefaciens was found in a ratio of approximately 1 to 15 with B. succinogenes. Degradation of xylan and cellulose, measured by in vitro dry matter disappearance after inoculation with fecal samples, was significantly greater for pigs fed the high-fiber diet than that for the controls. These data suggest that the number of fibrolytic microorganisms and their activity in the large intestine of the adult pig can be increased by feeding pigs high-alfalfa-fiber diets and that these organisms are similar to those found in the rumen.     

Development of an immunosensor for human ferritin, a nonspecific tumor marker, based on surface plasmon resonance

A direct human ferritin immunosensor was developed using anti-human ferritin monoclonal antibodies (MAbs) immobilized on the gold surface of a self-assembled surface plasmon resonance (SPR) apparatus. A kind of self-assembled monolayer (SAM) prepared by cystamine-glutaraldehyde method was applied to immobilize the MAbs. The reusability of the sensor chip adopting the SAM was found to be better than the other immobilization methods including adsorption, protein A, concanavalin A method. Ten cycles of measurements could be performed on the same chip regenerated with a 0.1M HCl solution. A linear relationship existed between the angle shifts (millidegrees) and the log values of ferritin concentrations in the range from 0.2 to 200 ng/ml in buffer and human serum. When used for 15 days, the angle shifts were all >95% of those on the response at the first day. A 10 M NaOH solution was used for clearing nonspecific binding in human serum. Correlation coefficient was 0.991 between this SPR method and chemiluminescent immunoassay for determination of ferritin in clinical human serum samples. The SPR sensor offers advantages of simplicity of immobilization, high sensitivity, high specificity, low sample requirement, high reusability, no label and no pretreatment etc.     

Nutrient fluxes in the shifting cultivation system of south-west Côte d'Ivoire

At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.