Open Bucket Research Articles

Assessment of radioactivity in particulate matter and soil from selected mining towns of Erongo region, Namibia

The presence of radionuclides in particulate matter (PM) associated with mining operations in communities located at the edge of the mine sites have been either greatly ignored or poorly understood, leading to the underestimations of the radionuclides concentrations in PM and health impact. In this study, measurements of radioactivity in PM and soil were made in the two mining towns of Karibib and Arandis to assess the human health radiological impact on the people around the mining sites. Dust fall samples were collected for a period of six months i.e. May 2017 to October 2017 using open bucket sampler procedure according to the American Society for Testing and Materials Standard Method (ASTM D1739) while some soil samples were collected using a soil auger. The samples were measured for the presence radionuclides using a well calibrated gamma-ray spectrometer coupled with a high purity germanium detector.In particulate matter samples, the mean activity concentrations of 226Ra, 238U, 232Th, 210Pb, and 40K were found to be 81.24±1.00, 57.99±2.61, 72.10±1.67, 55.89±6.21, 682±19.81 Bq.kg−1, respectively. Similarly, in soil samples, the mean activity concentrations were found to be 66.41±1.77 Bq.kg−1 for 226Ra, 52.79±3.40 Bq.kg−1 for 238U, 71.30±2.40 Bq.kg−1 for 232Th, Bq.kg−1 for 71.50±5.99 210Pb and 797.36±18.26 Bq.kg−1 for 40K. The activity concentrations revealed higher levels of radionuclides associated with the 238U series, which were distributed unevenly across the sites. The results were comparable to global values of 11 to 64 Bq.kg−1 for 238U, 17 to 60 Bq.kg−1 for 232Th, and 140 to 850 Bq.kg−1 for 40K.The activity concentrations were used to compute the absorbed dose (D), annual effective dose equivalent (AEDE), radium equivalent activity concentrations (Ra eq), external and internal hazard indices (H ex and H in), Gamma Index (Iγ), Alpha Index (Iα) and excess lifetime cancer risk (ELCR). The mean radiological parameters in most samples were found to be within acceptable limits, with Raeq 370 Bq.kg−1, which corresponds to an upper safe limit of AEDE of 1 mSv.yr−1, the prescribed safe limit by the International Commission on Radiological Protection (ICRP), and thus the potential radiological health effects may not be significant.

Carrying children, groceries, and water across varying terrain: Changes in gait and comfortable walking speed

BackgroundCarrying items of substantial weight and value in one’s arms while traversing challenging terrain is a common task that requires considerable care. Carrying valuable (e.g., child) or variable (e.g., water) items, compared to stable ones (e.g., groceries) demands increased coordination, and is likely to lead to slower comfortable walking speed (CWS) and altered gait mechanics, especially on difficult terrain. Research questionHow are gait parameters altered by carrying items of substantial weight and varying value and dynamics across more and less demanding terrain? MethodsIn two experiments, participants carried their child, an equally weighted sack of groceries, or an open bucket of water in the same manner across level floor and across uneven stairs of varying heights with gaps between them. Kinematics were assessed for both terrains; kinetics were measured for one step up and one step down on stairs. ResultsMixed models ANOVAs with repeated measures revealed that CWS on uneven stairs was approximately 65 % of CWS for level floor, regardless of the item carried. Step-to-step coefficients of variation for step length and CWS were also greater. Water was carried most slowly, with shorter steps on level floor and reduced accelerations on uneven stairs. CWS with children and groceries did not differ. SignificanceCarrying items of weight and worth with varying dynamics across more and less challenging terrain illustrates the ecological complexity of walking. Terrain requiring greater flexibility, strength, and coordination reduced CWS substantially, a complexity-speed tradeoff. More variable, difficult to control items altered CWS and other gait patterns regardless of terrain difficulty, suggesting terrain and item dynamics contributed independently to gait adjustments. More valuable items were not carried more slowly than less valuable ones. Carrying tasks deserve greater attention in research and clinical assessment.

Milk- and starter-feeding strategies to reduce cross sucking in pair-housed calves in outdoor hutches

Social housing of preweaned calves can benefit their welfare, but housing and cross sucking are potential barriers to adoption for farmers. For farms using outdoor hutches, an option is to pair adjacent hutches with a shared fence. Our objective was to investigate milk- or starter-feeding strategies to mitigate cross sucking in this system. Holstein heifers were housed in pairs (n = 32 pairs) and divided into 4 treatments (n = 8 pairs each) in a 2 × 2 factorial design: milk in an open bucket with starter in only a bucket (OB-SB), milk in an open bucket and starter in both a bucket and a specialized teat bottle (Braden bottle; OB-BB), milk in a slow-flow teat bucket with starter in only a bucket (TB-SB), or milk in a slow-flow teat bucket and starter in both a bucket and a specialized teat bottle (TB-BB). When starter was first offered (d 6 ± 1 of life, mean ± SD), calf latency to approach was recorded, averaged within pairs, and compared between starter treatments using a linear mixed model with fixed effect of treatment and random effect of pair within treatment. Calves were initially bottle fed; milk treatments began on d 14 ± 1 of life and ended when calves were completely weaned (d 53 ± 1). Calves were observed for behaviors such as drinking milk and cross sucking twice weekly for 30 min during the afternoon milk meal using continuous video, with values averaged within pairs. Linear mixed models were run separately before (wk 3-6) and after (wk 7-8) weaning, with fixed effects of milk- and starter-feeding treatments, week, and the 2- and 3-way interactions, with week as repeated measure and pair as subject. Pairs with Braden bottles and buckets approached starter sooner than those with only buckets (Braden bottles vs. no Braden bottles: 13.1 ± 6.1 vs. 33.2 ± 6.1 min, LSM ± SEM). Before weaning, pairs with open buckets for both milk and starter cross sucked for at least twice as long (OB-SB: 2.9 ± 0.3 min) as all other treatments (OB-BB: 1.5 ± 0.3 min; TB-SB: 0.4 ± 0.3 min; TB-BB: 0.5 ± 0.3 min). This pattern held during weaning, when cross sucking increased overall (OB-SB: 3.9 ± 0.4 min; OB-BB: 1.8 ± 0.4 min; TB-SB: 0.9 ± 0.4 min; TB-BB: 1.6 ± 0.4 min). Regardless of starter treatment, calves spent less time cross sucking when fed milk in teat buckets, which extended the milk meal relative to open buckets (teat bucket vs. open bucket: preweaning = 7.0 ± 0.2 vs. 1.6 ± 0.2 min; weaning = 3.0 ± 0.1 vs. 0.6 ± 0.1 min). When calves are fed milk in open buckets, a novel option for reducing cross sucking is to provide starter through a specialized bottle. Nonetheless, providing milk in slow-flow teat buckets had the greatest effect on reducing cross sucking by directing suckling to the teat instead of another calf or pen objects.

PSII-18 Effect of two different milk-feeding methods on performance and plasma glucose of dairy calves

Abstract The objective of this study was to evaluate two different methods of milk feeding calves and the effects on performance and plasma glucose. Thirty newborn Holsteins calves were individually housed with free access to water and starter concentrate and fed 6 L/d of whole milk divided in two meals (7h and 17h). A randomized blocks experimental design was used, with weight and day of birth as blocking effect, and calves were distributed in two methods of milk-feeding: (1) open bucket; (2) bucket with an artificial teat. Milk-feeding period started with 3 d of age, after colostrum feeding by bottle. The starter intake was monitored daily. Speed of milk intake, body weight and measures, and blood samples were taken weekly. Data were analyzed using the proc mixed of SAS for repeated measures, and the means were compared using the F test (P ≤ 0.05). Feeding milk using a bucket with an artificial teat decreased average daily starter intake (P < 0.03), probably because calves were more satisfied by the act of suckling. However, there were no effects on body weight gain, weight at weaning and average body measures. The bucket with artificial teat had a positive influence on blood glucose concentration, measure 2h after milk feeding (P < 0.01), as a response of lower speed for milk intake (P < 0.01). These results suggest that the speed for milk intake may interfere on blood glucose concentrations peak, however because the behavioral need of suckling is attended, it may decrease starter intake, but without decrease performance.

Long-Duration Thermal Decomposition of Waste based upon existing coke and plasma technology

The current global problem of accumulation of municipal solid waste (MSW) and a possible way to solve it is considered. To date, there are different ways to treat MSW: recycling (processing), incineration and disposal. Each of them has its advantages and disadvantages. Waste disposal is the least environmentally safe method, but now it is the main one in Russia because of its availability. This article proposes a scheme for recycling MSW, which is based on already existing coke, energy and plasma technologies. Within the scheme thermal destruction of waste is carried out in a coke battery, and the subsequent melting of the residue is carried out using plasma technologies (in an electric arc furnace or in an open bucket with heating from the plasmatron). The plasma module, in which the melting takes place, can be implemented both with the circuit in question and attached to an existing incinerator. The result of melting is a low-grade stone that does not need to be buried. Gases released from MSW in the process of thermal destruction, after deep cleaning, are used to generate electricity. The source of thermal energy required for the operation of the proposed scheme for recycling solid waste is thermal power plants using natural gas as fuel. The interaction between the flue gases passing through the coke oven battery and leaving the TPP with coke oven gases is excluded due to the design features of the coke oven battery. This allows you to dramatically reduce the amount of gas to be deep cleaning, which significantly reduces the cost of cleaning equipment. The use of coke-oven batteries of modern design minimizes environmental pollution. The article assesses the energy consumption for the implementation of the proposed scheme for a plant processing 100 thousand tons of solid waste per year. The source of thermal energy for which is the standard unit of thermal power plants with a capacity of 500 MW. It is shown that working in conjunction with a waste recycling plant changes the heat balance of TPPs by no more than 10%.

Sub-Kelvin cooling for two kilopixel bolometer arrays in the PIPER receiver.

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne telescope mission to search for inflationary gravitational waves from the early universe. PIPER employs two 32 × 40 arrays of superconducting transition-edge sensors, which operate at 100 mK. An open bucket Dewar of liquid helium maintains the receiver and telescope optics at 1.7 K. We describe the thermal design of the receiver and sub-Kelvin cooling with a continuous adiabatic demagnetization refrigerator (CADR). The CADR operates between 70 and 130 mK and provides ≈10 μW cooling power at 100 mK, nearly five times the loading of the two detector assemblies. We describe electronics and software to robustly control the CADR, overall CADR performance in flightlike integrated receiver testing, and practical considerations for implementation in the balloon float environment.

Evaluation of some heavy metals loading in dust fall of three universities motor parks in Western Nigeria

The high density of vehicles that run to and fro University campus to town has become of great concern for assessment of health status of the ambient air around the Universities motor parks. Moreover, some of the University’s parks are unpaved while the paved ones are old and unmaintained. Dust fall samples in parks of Universities of Ilorin, Ibadan and Kwara State University were collected for five months spanning from 1st November 2014 to 31st March, 2015 using open bucket sampler based on ASTM D 1739 of 1998 (2010). A 0.1 g of dust sample was digested with 20 ml of HNO3, HClO4 and HF in ratio of (3:2:1) respectively and heavy metals (Mn, Cu, Zn, Cd, Pb, and Ni) were analysed using atomic absorption spectrophotometer (Buck Scientific model 210 VGP). Results of heavy metal concentrations showed decrease in the following order: 1479.75, 1255.68, 241.50, 128.00, 85.25, and 9.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively for University of Ibadan. The decreased in concentrations of heavy metals obtained for University of Ilorin motor park dust-fall were found to be 1145.75, 797.75, 219.63, 133.51, 58.25 and 23.13 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively. For Kwara State University, decrease in the following order: 778.5, 323.88, 259.38, 101.38, 34.38, and 4.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively were obtained. Generally for the three sites used, the heavy metal concentrations decreased in the following order: Mn>Zn>Pb>Ni>Cu>Cd. This implies that dust-fall in the parks are heavily loaded with some heavy metals that are of concentrations above Romania standard threshold limit for Cd and Pb while concentration values obtained for Ni are higher than US- EPA values (75 mg/kg). The regulatory agent or management should ensure that the roads are paved and there should be intermittent wetting of the roads with water.Keywords: Dust Fall; Heavy Metals; University Motor Parks

PHEROMONE BAITED TRAP FOR THE MANAGEMENT OF RED PALM WEEVIL, Rhynchophorus ferrugineus F. (Coleoptera: Curculionidae) POPULATION IN COCONUT PLANTATIONS

4-methyl-5-nonanol (ferrugineol), the major component of theaggregation pheromone of Rhynchophorus ferrugineus F. was evaluated as alure for trapping of this pest in coconut plantations in Sri Lanka. Trap design,longevity of ferrugineol in field conditions, and the effect of trapping ondamage incidence of R. ferrugineus were studied. N-pentanol, a knowncompound present in coconut stem volatiles was used in combination offerrugineol in all tested traps. Trap designs tested were; an open plasticbucket, a funnel trap, and a modified metal trap. The open plastic bucket (5 L)baited with ferrugineol-pentanol, which was hung on coconut palm stem at 1.5m, caught significantly more number of adult weevils than ferrugineolpentanolbaited funnel and metal traps. An open plastic bucket trap was sixtimes less expensive than the metal trap currently recommended by theCoconut Research Institute, Sri Lanka. Ferrugineol remained effective as abait for 12 weeks under field conditions. High capture rates of adult R.ferrugineus were obtained in ferrugineol baited open bucket traps inplantations where the initial damage incidence was high. Monthly surveys ofindividual palms during pheromone trapping revealed that a sharp reductionof the number of coconut palms damaged by R. ferrugineus in 10-hectareexperimental blocks. Continuous trapping of weevils with ferrugineol over aperiod of time significantly lowered the infestation of this pest.

Effects of Providing Water from a Bucket or a Nipple on the Performance and Behavior of Calves Fed Ad Libitum Volumes of Acidified Milk Replacer

Little information is available on how much water ad libitum milk-fed calves consume during the milk-feeding stage and during weaning to solid feed. Further, no information exists on the effects on calf behavior and performance of different water delivery systems during these stages. Therefore, the objectives of this study were first, to examine the water intake of calves fed acidified milk replacer ad libitum during the milk-feeding and weaning stages, and second, to determine whether the method of water delivery affected water and feed intake and growth during these periods or oral behavior during weaning. To evaluate this, we registered feed and water intake, growth, and oral behaviors of 24 dairy calves before and after abrupt weaning from a 7-wk ad libitum acidified milk replacer feeding regimen. Two water sources (open bucket and nipple) were compared. During the 7-wk milk-feeding period, the calves drank, on average, 12.9±0.7 L/d of acidified milk replacer but very little water. However, after abrupt removal of milk, the 2-mo-old calves rapidly increased their water intake. Moreover, no differences in water intake between the 2 water sources were noted either before or after abrupt weaning. Calves were observed to have some difficulties in using the water nipple. Calves provided water through the nipples consumed less water at each drinking bout but visited the water nipple more frequently compared with calves provided access to water from the bucket. We observed no differences in all other behaviors observed. Overall, the calves rapidly increased their feed intake, rumination time, frequency of cross-sucking, and vocalization after weaning. In conclusion, despite the calves’ consuming very little water when provided ad libitum access to acidified milk replacer, they dramatically increased their water consumption after abrupt weaning from milk. Calves did experience some difficulties in using the water nipples.

Effect of colostrum feeding method and presence of dam on the sleep, rest and sucking behaviour of newborn calves

In rats, sucking milk reduces anxiety and promotes non-rapid eye movement (NREM) sleep, and in calves it induces resting but the effect on sleep is unknown. Here, we investigated how calves’ sleep was affected by colostrum feeding methods. Forty-one calves were blocked by birth date and randomly allotted within blocks to the experimental treatments. Calves were housed for four days either with their dam (DAM) or individually with warm colostrum feeding (2 L four times a day) from either a teat bucket (TEAT) or an open bucket (BUCKET). DAM calves suckled their dam freely. Calves’ sleeping and sucking behaviour was filmed continuously for 48 h at the ages of two and three days. Behavioural sleep (BS) was defined as calves resting at least 30 s with their head still and raised (non-rapid eye movement) or with their head against their body or the ground (rapid eye movement, REM). Latency from the end of colostrum feeding to the start of BS was recorded. We compared behaviour of TEAT calves with that of DAM and BUCKET calves using mixed models. Milk meal duration was significantly longer for TEAT calves than for BUCKET calves (mean ± S.E.M.; 8.3 ± 0.6 min vs. 5.2 ± 0.6 min), but equal to that of DAM calves. We found no effect of feeding method on the duration of daily BS (12 h 59 min ± 1 h 38 min) but we found a tendency for the daily amount of NREM sleep; BUCKET calves had less NREM sleep per day than TEAT calves (6 h 18 min vs. 7 h 48 min, S.E.M. = 45 min) and also longer latencies from milk ingestion to BS (21.9 ± 2.0 min vs. 16.2 ± 2.0 min). DAM calves slept longer bouts than TEAT calves (10.8 ± 1.0 min vs. 8.3 ± 1.0 min) and less often (78 ± 4 vs. 92 ± 4). Sucking colostrum from a teat bucket compared with drinking from an open bucket increased sleepiness and the amount of NREM sleep. Individually housed, teat-bucket-fed calves slept more fragmentarily than dam-reared calves.

An Instrument to Measure the Temperature of the Cosmic Microwave Background Radiation at Centimeter Wavelengths

The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a balloon-borne instrument to measure the temperature of the cosmic microwave background at centimeter wavelengths. ARCADE uses narrow-band cryogenic radiometers to compare the sky to an external full-aperture calibrator. To minimize potential sources of systematic error, ARCADE uses a novel open-aperture design which maintains the antennas and calibrator at temperatures near 3 K at the mouth of an open bucket Dewar, without windows or other warm objects between the antennas and the sky. We discuss the design and performance of the ARCADE instrument from its 2001 and 2003 flights.

Voltage Spike and Magnet Quench Behavior in the NHMFL 900 MHz Bucket Test

The NHMFL 105 mm wide bore 900 MHz NMR magnet and protection system were tested in an open bucket cryostat as a qualification test of the integrated system for the first time. The relevant aspects of the superconducting magnet configuration and bucket test operation are discussed. The unique voltage spike and magnet quench behavior are described. A discussion is provided to substantiate the thesis that interface instabilities are the cause of the quenches.

Effects of amount of milk, milk flow and access to a rubber teat on cross-sucking and non-nutritive sucking in dairy calves

The aim of this study was to test the effects of different amounts of milk, flow rate of milk, and access to a teat after milk intake on non-nutritive sucking on an empty teat and on cross-sucking on other calves in Bos taurus dairy calves. An additional aim was to test if calves prefer to perform non-nutritive sucking on a teat with the taste of milk or on a clean teat. First experiment involved 11 groups of three calves during gradual decrease from 5 to 2.5 and 1 to 0 l of whole milk per meal twice daily. Milk flow was either 0.5 or 1 l/min, and the teat buckets were either left or removed after milk intake. When the calves were fed with 5 l of milk, non-nutritive sucking and cross-sucking decreased ( P<0.001), compared to 1 and 2.5 l. Removing the empty teat after milk intake increased cross-sucking ( P<0.001). Slow milk flow reduced non-nutritive sucking after milk intake ( P<0.05), but did not influence cross-sucking. Duration of recorded milk intake was similar with fast flow and 5 l of milk, compared to slow flow and 2.5 l of milk. The latter combination increased non-nutritive sucking and cross-sucking, suggesting that amount of milk is more important than duration of milk intake. Second experiment was carried out on 12 individually kept calves. The calves received 2.5 l of milk either in an open bucket, in a rubber teat bucket, or half/half in both buckets. When not used for feeding, the open bucket and the teat bucket were filled and emptied again to make them ‘tasty’ with some drops of milk. The tasty teat bucket was either removed or present after milk intake. The calves had always access to a second clean teat bucket. Source of milk had no influence on recorded behaviour after milk intake. The tasty teat was sucked for twice as long as the clean one when both teats were present ( P<0.001). When the tasty teat was removed, the calves increased sucking on the clean teat ( P<0.001), but decreased total time spent sucking ( P<0.001). We conclude that a high amount of milk and the presence of the teat bucket after milk intake reduces cross-sucking, and that a clean teat is less effective in encouraging calves to suck than a teat with taste of milk.

Effect of milkflow rate and presence of a floating nipple on abnormal sucking between dairy calves

The aim of this study was to investigate if access to an artificial teat compared to an open bucket would decrease abnormal sucking in calves held in pairs, and if the calves would perform less abnormal sucking if they spent more time drinking or sucking the milk. In total 16 calves of Swedish Red and White cattle housed in pairs were used. The eight groups were given 2.5 l of whole milk per calf, twice a day in one of the following treatments; bucket with fast flow (control), bucket with slow flow, floating nipple with fast flow and floating nipple with slow flow. All groups were subjected to the four different treatments in a random balanced order. Two buckets were connected with a rubber pipe in order to control the milk flow. In the fast treatments, the milk poured from one bucket to the other in 40 s, and in the slow treatments the milk poured from one bucket to the other in 10 min. Each group had the treatment for 6 days before behavioural observations were done on day 7. These were made by instantaneous recordings at 20 s intervals for 30 min, starting when the calves received their milk in the morning and afternoon. The number of recordings of abnormal sucking was lower than the control in all treatments ( P<0.001). The lowest recording of abnormal sucking was found, when the calves had both a floating nipple and a slow flow. Sucking on other objects in the pen had the highest number of recordings, when they had a nipple and a fast flow ( P<0.01), but the sucking on the empty nipple represented 95% of this category. The calves tended to lick and bite more on the bucket, the nipple and pen fittings in the two treatments with fast flow ( P<0.1) than in the slow treatment with nipple. It is concluded that both the performance of sucking and the time taken to ingest milk are important in order to decrease abnormal sucking between calves.

Dust characteristics and source‐sink relations in eastern West Africa (SW‐Niger and Benin) and South America (Argentinean Pampas)

AbstractIn order to quantify dust input and to describe its characteristics under different environmental conditions, and to get information on source‐sink relation, dust was collected monthly with bulk deposition samplers (open bucket type) in 2 and 4 m height over a 2—3 years period at different sites in West Africa (SW‐Niger and Benin) and in the semi‐arid Argentinean Pampas.Dust input, mineralogy (bulk and clay), chemical properties including total element content and particle‐size distribution showed a clear seasonal pattern in eastern West Africa. Far‐transported Saharan dust in the dry season could be distinguished from local material transported in the rainy season. In Argentina, high sand content of the samples pointed to an important participation of local components in the collected material. This was supported by higher contents of seaborne salts at the coastal sites, and the highest amounts of collected dust at the site of highest wind velocities. Due to the lack of seasonal differences in dust amount and its characteristics, and the aeolian genesis of the Pampas soils, a separation of local material and long‐range dust was not possible.

Deposition rates and characteristics of aeolian dust in the semi-arid and sub-humid regions of the Argentinean Pampa

Atmospheric dust inputs were monitored at four sites in the south-western Argentinean Pampa over a 3-year period. Dust traps (open bucket type) were installed at the soil surface and at 2 and 4 m above the surface. Total deposition rate, mineralogy, chemical properties, total element content and particle-size distribution of dust and soil samples of adjacent soil profiles were determined and analysed. Rainwater was also collected and analysed for salt content. Dust input varied between 400 and 800kgha−1year−1averaged over 3 years, and did not follow a clear seasonal pattern. An unexpectedly high fine sand content in the dust samples and higher salt content of dust and rainwater at the coastal site indicate the participation of an important local component in this area. Feldspars and quartz were the principal constituents of the bulk mineralogy. Additional components were volcanic glass, micas, magnetite and calcite. The nutrient status of the dust was greater than that of the surrounding soil, and therefore may serve as a renewal factor. Nutrient input is a function of dust quantity and distance from the sea.

Bird urate contamination of atmospheric dust traps

The chemical analysis of atmospheric dust from Niger, West Africa occasionally yielded more water soluble K than could be expected from soil derived dust. The high K values were correlated with samples containing white sand-sized particles. These particles were examined optically and chemically, and by X-ray diffraction and scanning electron microscopy. These white particles were identified as uric acid dihydrate. Their most probable origin was from bird urine by birds perching on the open bucket traps. Bird urine contains soluble cations interspersed with the more insoluble uric acid. We should be cautious in assuming that only atmospheric dust is collected in dust traps. The addition of only a small amount of bird urine may easily invalidate the chemical analysis of atmospheric dust. Dust traps should be designed to prevent the perching of birds.

Characteristics of aeolian dusts in Niger, West Africa

Dust-laden Harmattan winds are a recognized phenomenon of the Sahel region of Africa. Atmospheric dust inputs have been monitored at two sites in Niger, West Africa since July 1985. Dust traps of the open bucket type were placed 2.5 and 5 m above the soil surface. Dust was collected and analyzed quarterly for total infall, particle size, mineralogy, and water-soluble and exchangeable cations. Surface soil samples adjacent to the dust traps were also analyzed for the same properties. Of the ∼2000 kg ha −1 yr −1 of dust infall, over half came during April to July, after the Harmattan wind season. Atmospheric dust inputs varied by season as did particle size, being coarser during periods of minimal infall. The dust contributes ∼ 4.8, 2.8, 1.1 and 0.6 kg ha −1 yr −1 of exchangeable plus watersoluble Ca, K, Mg and Na, respectively. The nutrient status of the dust is substantially greater than the native soil and may serve as a nutrient renewal vector.

Flow and stability of helium II between concentric cylinders

We discuss our present knowledge of the flow and stability of helium II between concentric cylinders. The flow problem for helium II leads us to consider the formation of quantized vortices in the uniform rotation of helium II in an open bucket as well as quantized circulation states and vortices in a rotating annulus. We then consider how to treat the first appearance of vortices in the presence of shear, which allows us to characterize the basic flow which must be examined for stability. The results suggest an explanation for heretofore unexplained experiments. Future directions for research on the stability of helium II are suggested.

Effects of Space Shuttle Exhaust Plumes on Gills of Some Estuarine Fishes: A Light and Electron Microscopic Study

The first few launches of the space shuttle resulted in fish kills in a lagoon near the launch site. To study this phenomenon further, sheepshead minnow (Cyprinodon variegatus), sailfin molly (Poecilia latipinna), and mosquitofish (Gambusia affinis) were exposed to the exhaust plume in buckets placed near the launch site. An open bucket provided a full exposure, a partly closed one provided an intermediate exposure, and a closed one was the control. Three h after launch, the pH of the water from the full exposure had decreased from about 7 to about 3, Al and Fe levels had increased, and some fish had died. Gills ol most fishes from full exposures and some from intermediate exposures were damaged. Gills, however, exhibited no aneurysms, mucus coagulation, or hemorrhaging. Some secondary lamellae swelled, some fused with adjacent lamellae, and others clubbed or retracted into the filament. Many lamellar pavement cells died and sloughed off. Mucous cells of intermediate exposure specimens bulged on the filament surface and pavement cells lost their microridges. Mineral deposits, probably aluminum oxide, occurred on gills of fishes from full exposures. Focally, pavement cells were eroded exposing the underlying structures. The sudden pH drop in the full exposures probably caused the gill damage. However, we could not determine the effect of previous exposure on the experimental fish, or whether gill damage was the lethal lesion. The possibility is indicated that some fish recover after exposure to the exhaust plume.