Corrections to Kusnetz method for measurements of radon progeny concentrations in air

In 1956, H.L. Kusnetz proposed a quick method for radon progeny concentration measurement in mine atmosphere using a single gross-alpha count of a membrane-filtered air. The method is still widely used today and is based on a number of impractical assumptions. An instantaneous sampling time (less than ten seconds), is one of these assumptions that ignores the build-up and decay of the progeny on the filter paper during the sampling period, which is typically in the order of a few minutes. Of special concern is the 214Bi decay during the sampling period, since 214Po's alphas are lost during the sampling time and cannot be accounted for during the counting time. In addition, the method assumes that 214Bi activity during the counting period is constant. This inaccurate assumption can result in a smaller count rate, especially when counting times are long. Hence, underestimated working levels are expected when using Kusnetz factors without correcting for the sampling and counting times. In this technical report, exact sampling and counting time corrections to the method are provided along with the updated Kusnetz factors that correspond to common equilibrium conditions to correctly estimate the Working Level in air. Additionally, time corrections to the commonly used self-absorption correction formula and the lower level of detectability (LLD) equation used for any sample measurement are given.

Wintering waterbird assemblage in an emerging wetland of West Bengal, India: characterization for conservation management

Waterbirds constitute a prominent biota and reflect the ecosystem health and functionality of the freshwater wetlands. Documentation of the bird species assemblages of wetlands is therefore carried out as a part of monitoring of wetlands from a sustainability viewpoint. Using the emerging wetland of Purbasthali, West Bengal, India, as a model study area, the diversity of the associated bird species was estimated to supplement necessary information for conservation management of birds and ecosystems. The point count method was applied to count the waterbirds from each sighting location with a 25 m radius covering 360° arc and the counting period lasted 10 min for each site, and counts were made in the winter of 2016/2017. The data on the waterbirds encountered were recorded and subjected to diversity analysis, including the residential status, global population trend and feeding guilds. Apparently, the wetland was considered as suitable habitat for 27 waterbird species, which could be grouped under 24 genera, 10 families and 5 orders. Among these, the family Anatidae with maximum relative density and abundance dominated in the wetland. Out of the 27 recorded species, 5 species were widespread winter visitors, 3 species widespread resident, as well as, widespread winter visitors and 2 species were sparse local winter visitors. A globally near threatened species, the Black-headed Ibis (Threskiornis melanocephalus) was very common in the sampling sites. The waterbird assemblage in the wetland was dominated by carnivores followed by omnivores and herbivores. The abundance of the waterbirds with considerable variations in the foraging guild reflects availability and exploitation of multiple resources of the Purbasthali wetlands. Prominence in the differences in relative abundance of the different waterbirds could be linked with the heterogeneity in the habitat quality. The present information on waterbird assemblage calls for appropriate measures for conservation of the species and appropriate management of Purbasthali wetlands.

Seasonal Variation in Wild Ungulate Abundance in a Hunting-Ban Beech Forest: A Case Study of Amiata Mountain, Central Italy

Several studies have focused on the impact of ungulates on agricultural systems, but the magnitude of their antagonistic role in forest renovation dynamics has long been underestimated and is rarely considered. The abundance of ungulate species is susceptible to seasonal variations according to their autecology, human management choices, and territorial planning. Therefore, the appropriate choice of counting period is crucial. In this case study, we used camera traps to assess the seasonal abundance variations of wild boar and roe deer in a 560-hectares hunting-ban beech forest (95.48%) in southern Tuscany managed for timber production. Camera-trapping sessions were performed in both early summer and autumn. The roe deer abundance index is higher in early summer, although statistically not significant, potentially affecting seedling survival. Inversely, wild boars significantly (F = 79.125; p = 0.001) increase their abundance at the local scale in autumn when probably, according to the ecology of fear, they shift their home range toward refuge areas temporary. In autumn, the high density of wild boars can reduce seed availability at the local scale. Further analyses assessing the correlation between seasonal wild ungulate abundance and forest regeneration rates are in progress, based on data recorded within and around three fenced sample plots.

Evaluation of the Space Syntax Measures Affecting Pedestrian Density through Ordinal Logistic Regression Analysis

This paper examines the relationship between pedestrian density and space syntax measures in a university campus using ordinal logistic regression analysis. The pedestrian density assumed as the dependent variable of regression analysis was categorised in low, medium, and high classes by using Jenks natural break classification. The data elements of groups were derived from pedestrian counts performed in 22 gates 132 times. The counting period grouped in nominal categories was assumed as an independent variable. Another independent was one of the 15 derived measures of axial analysis and visual graphic analysis. The statistically significant model results indicated that the integration of axial analysis was the most reasonable measure that explained the pedestrian density. Then, the changes in integration values of current and master plan datasets were analysed using paired sample t-test. The calculated p-value of t-test proved that the master plan would change the campus morphology for pedestrians.

Quality Measure of Short-Duration Bicycle Counts

The average annual daily bicyclists (AADB) measure is commonly used in research and practice as a metric for cycling studies, such as bike ridership analysis, infrastructure planning, and injury risk. It is estimated in one of two ways: by averaging the daily cyclist totals measured throughout the year with a long-term automated bicycle counter, or by using a long-term bicycle counter to extrapolate data from a short-term counting site. Unfortunately, extrapolation of a short-term bicycle counting site can produce inaccurate AADB estimates as a result of different error sources; the range of possible error is highly correlated to several characteristics of the short-term count, such as the counting period, flow intensity, and time of year. This paper proposes a simple method to estimate the quality of a short-term count through a single metric combining five factors associated with the count variation: duration, average demand, time of year, stability, and correlation with the reference count. The method is validated with the use of a relatively large data set of automated bicycle counts. The quality measure, with a range from 0 to 10, is negatively correlated with the absolute relative error (ARE) of the AADB estimation. Results show distinct ARE distributions for different quality measure classes. The average ARE for the lowest quality class is 13.5% compared with an average ARE of 3.0% for the highest quality class. The maximum ARE (95% confidence) is 35% for the lowest quality class compared with 7.5% for the highest quality class.

Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating

We have tested two versions of an 0.8-ml volume Teflon® vial, designed specifically for radiocarbon dating in the microvolume range, using a modern Quantulus 1220™ liquid scintillation (LS) spectrometer. We determined the counting performance of each vial type in conjunction with different designs of copper holder, viz., with and without the incorporation of a “Teflon® light coupler”. We also compared the losses of sample benzene during a typical 28-day counting period. Results show that neither vial design nor the type of vial holder used in the intercomparison had a significant influence on counting performance. We recorded an absolute 14C detection efficiency of 82% against a background count rate of 0.1 cpm, i.e., a “figure of merit (FM) value” = 67,240. This compares favorably with the operational parameters anticipated for microvolume 14C dating by modern LS spectrometry. However, variations in the design of the sealing method used between the vial types was reflected in an apparent approximate tenfold difference in the amount of benzene lost during routine counting. In the better case, the evaporation loss was equivalent to 0.032 mg of benzene per day.

A Simple Method of Estimating Cerebrospinal Fluid Pressure During Lumbar Puncture

It is often difficult to measure cerebrospinal fluid (CSF) pressure in children. CSF flow through a spinal needle is described by the equation: Flow = pressure/(needle constant x relative viscosity). Thus, CSF flow rate during lumbar puncture can be used to estimate CSF pressure. Because the viscosity of CSF is approximately the same as that of normal saline, 0.9% NaCl was used to model CSF flow in vitro. Flow of saline through various spinal needles was measured as pressure and temperature were varied to determine needle constants and variation in viscosity with temperature. Counting periods for which the number of drops counted equals the pressure (in centimeters of H2O) then were determined for each needle size. At patient temperatures less than 40°C, counting periods were calculated at 21, 39, and 12 seconds, for 22-gauge 1.5-inch, 22-gauge 3.5-inch, and 20-gauge 3.5-inch spinal needles, respectively. Viscosity decreased slightly above 40°C, and counting periods became 20, 37, and 11 seconds. Finally, the method was tested prospectively in 12 patients by comparing drop count (over the calculated counting period) to manometric pressure measurement. Drop counts were within 15% of manometric pressure in all patients. This method allows simple and rapid estimation of CSF pressure during lumbar puncture.

A Counter System for High-Precision 14C Dating

A multicounter radiocarbon dating system was developed applying the experiences of the previous one-channel low-level counting facility. The counter system consists of nine electrolytic copper proportional counters of identical diameters with sensitive volumes of 0.35–0.7dm3 and filled with either methane at high pressure (6 bar) or CO2 at 1 bar. The inner counters are surrounded by an anticoincidence shield consisting of five multiwire proportional flat counters filled with propane. The pulses of the detectors are handled by integrated amplifiers, discriminators and anticoincidence units interfaced to a microprocessor-controlled data evaluation unit. Software is written in BASIC using ASSEMBLER sub-routines. The overall precision of the system for modern carbon samples using high-pressure methane-filled counters (B ≍ 0.7 cpm, S ≍ 14 cpm) is better than 4 after a counting period of seven days.

Natural Radioactivity in the Principal Constituents of French River Ecosystems

The study is based on data covering the water, sediments, plants and fish sampled over a 20-year period at 15 stations along French rivers. Three geographic zones were investigated: one containing a uranium mining complex (Zone 1), another including five major rivers along which nuclear power plants are sited (Zone II) and a third unaffected by nuclear activities (Zone III). Natural radioactivity basically involves 238U, 226Ra and 210Pb in the uranium series, 232Th from the thorium series, 40K and 7Be. The natural radioactivity in Zone II is not different from Zone III, and is thus unaffected by waste discharges from nuclear power plants. The most abundant radionuclide is 40K, while the other nuclides are often found in trace amounts near the detection threshold of the analysis method used (Ge gamma spectrometry with a 15-hour counting period). The 226Ra and 238U concentrations observed in Zone I are at least an order of magnitude higher than in the other two zones due to authorised waste discharges from the Lodève mining complex, but only a small stream is affected. The measured 226Ra concentrations would result in an annual whole body committed dose equivalent attributable to a 200 g weekly fish consumption from this stream of 4.4 x 10-5 Sv.y-1, or 0.86% of the maximum permissible dose (5 mSv).