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Objective This paper reports the results of a community trial to measure the clinical impact of a linked series of interventions on Early Childhood Caries (ECC) and general caries levels among five-year-old children. It exemplifies the problems of undertaking population based interventions in deprived communities. Research design Two health districts (Primary Care Groups) were matched for dental disease levels and socio-demographic factors. One was randomly allocated to be the active intervention PCG, the other the comparison PCG. Children in the active PCG received a series of interventions to support positive dental health behaviour from the age of 8 to 32 months. Clinical examinations were undertaken on a cohort of 5-year-old children in both active and comparison PCGs. Setting In the active PCG, children who attended designated clinics for their 8-month developmental checks and/or MMR inoculations at 12 to 15 months, were given gift bags, the first contained a trainer cup, the second fluoride toothpaste (1450 ppm F) and toothbrush. Parents were also given written, pictorial and verbal advice on oral care. Further supplies of toothpaste and brushes were posted to the children's homes at 20, 26 and 32 months. When five years of age children in the two PCGs were examined in school. Outcome measures Severity and prevalence of ECC and general caries. Levels of participation. Results Among participants in the active PCG the prevalence of ECC, general caries and extraction experience and mean dmft (20%: 54%: 3%: 2.2) were lower than in 'participants' in the comparison area (32%: 64%: 12%: 3.7). All differences were statistically significant. When all children (participants and non-participants) in the two PCGs were compared, the differences were much reduced (30%: 63%: 6%: 3.1 vs. 32%: 64%: 12%: 3.6). A higher proportion of children in the active PCG area (47%) were found not to have participated in the interventions, when compared to 21% in the comparison area. Disease levels in the non-participants in the active PCG were particularly high. The impact of participation bias, changes in baseline balance, population mobility and alternative study design on outcomes are explored. Conclusion The impact of non-participation in a deprived, urban conurbation with high levels of population mobility are sufficient to dilute the impact of a health intervention such that few benefits are discernible at a population level. [ABSTRACT FROM AUTHOR]

Soil deficiencies of zinc (Zn) and boron (B) limit crop production in Nepal. Improving the micronutrient status of plants would increase yield and increase micronutrient content of the seeds, leading to better nutrition of the progeny crop and to improved human micronutrient nutrition. The primary micronutrient problem in grain legumes is B deficiency, while in rice (Oryza sativa), Zn deficiency is more important, and wheat (Triticum aestivum) suffers from both deficiencies. A series of field experiments was carried out over two seasons to compare soil fertilization and micronutrient seed priming as methods of improving Zn and B nutrition of each crop. Micronutrient treatments were evaluated for their effect on grain yield and grain micronutrient content. Soil B fertilization increased B content of the grain of lentil (Lens culinaris), chickpea (Cicer arietinum), and wheat by a factor of two to five, while increasing the yield of chickpea only. Soil fertilization with Zn had no effect on yield of any crop, but resulted in a small increase in Zn in wheat grain. Sowing micronutrient-primed seeds had no effect on yield or micronutrient content of the progeny seeds in most cases. During the first season, the primed chickpea seeds failed to emerge at either site, causing complete yield loss, but this negative effect was not observed in the second season with similar priming treatments at nearby sites, and no effect of priming on yield was observed with any other crop in either season.

Objective This paper reports the results of a community trial to assess the effects of a multi stage dental health promotion programme in reducing Early Childhood Caries (ECC). Research design Two health districts (primary Care Groups) were matched for dental disease levels and socio-demographic factors One was randomly allocated to be the test Primary Care Group (PCG), the other the control PCG Children in the test PCG received a series of interventions to support positive dental health behaviour from the age of 8 to 32 months. Interviews were conducted with parents of children aged 21 months and clinical examinations were undertaken on a larger cohort of children aged 3-4 years in test and control PCGs. Setting The interventions were gift bags containing a trainer cup, toothpaste containing 1,450 ppm F and toothbrush, and advice given to the children's parents on attendance at designated clinics and medical practices and further paste and brushes posted to the children's homes. Parents were interviewed on the telephone. Examinations took place at Children's Centres and nursery departments attached to primary schools. Outcome measures Severity and prevalence of ECC and general caries and proportion of parents reporting adopting dentally healthy behaviours. Results In the test PCG the prevalence of ECC in children who had received the interventions was 16.6% compared with 23.5% of children in the control area. a reduction of 29% (p-0.003). The mean dmft (1.17) and prevalence of general caries experience (28.7%) in the test children were also significantly lower than for children in the control PCG (1.72: 39.2%) (p=0.001). Analysis from a community perspective, which included data from all children examined in both areas, showed the prevalence of ECC in the test and control PCGs was 21.3% and 22.8% respectively and the mean dmft 1.47 and 1.72. The proportion with general caries experience remained statistically significant in favour of the test area 33.8% vs 39.9% (p=0.01). Parents in the test PCG were more likely to report cessation of bottle use (33% vs 18%), use of sugar free drinks (49% vs 24%), commencement of brushing before first birthday (45% vs 27%) and twice daily brushing (52% vs 34%) Conclusion The parents who received this multi-stage intervention were more likely to report adoption of three positive oral health behaviours; using a trainer cup from one year of age, using safe drinks and brushing twice daily with a fluoride toothpaste. The programme failed to reduce the prevalence of ECC in the community but the prevalence of ECC and general caries experience among the children who participated was less than among children in the control PCG. [ABSTRACT FROM AUTHOR]

Chiral complexes of aluminum containing the salcyen ligand framework, [(R,R)-salcyen]AlX (X = Me, OSiMe2^tBu), catalyze the asymmetric addition of diorgano-H-phosphonates to carbonyls:  the phospho-aldol reaction. Reaction proceeds smoothly at ambient temperature in various solvents and under aerobic conditions, to afford α-hydroxyphosphonate esters (MeO)2P(O)CHR(OH), with enantiomeric excesses (ee's) <50%. Although catalyst activity is linked to the nature of X, ee's appear to be only slightly affected. Substitution within the chiral salcyen ligand framework seems to affect ee principally where there is a steric or structural change near the metal center. Although catalysis is tolerant of small quantities of water, excess water leads to attenuation of enantioselectivity through decomposition of catalyst to afford hydrated aluminas which competes through achiral phospho-aldol catalysis. Kinetic analyses reveal a second-order polynomial relationship of the form x/([A0] − x)[A0] = k2t + k2t², where [A0] is the initial concentration of H-phosphonate and carbonyl and x the degree of reaction. This may suggest that the metal complex must first be converted to another, more active precursor prior to catalytic turnover. Hammett analyses suggest that carbonyl binding to the metal center results in enhanced ee's, while single-crystal analyses on four aluminum complexes support the view that twisting of the ligand framework, as measured by the five-coordinate τ parameter, from a purely meridional geometry may be advantageous to stereoselectivity. Strategies for future developments are discussed in light of the results herein.

Experiments were designed to investigate the validity of proposed reaction‐diffusion models of denitrification. Brass respirometers were used to measure fluxes of oxygen (O2), carbon dioxide (CO2), and nitrous oxide (N2O) from a 5 × 10−3‐m layer of saturated soil incubated at 25°C. Gaseous fluxes were measured as a function of time after wetting, with and without 0.42 mol m−3of acetylene (C2H2) present in the headspace. The presence of C2H2in the headspace doubled O2fluxes 35 to 60 h after incubations commenced. When C2H2was not present, N2O evolution was negligible after 25 h of incubation. Nitrous oxide fluxes predicted by the models were compared to those observed experimentally. When C2H2was present, the models predicted N2O fluxes reasonably well (r2= 0.90 and 0.78) for initial nitrate (NO−3) N levels of 7.1 and 15.9 mg N kg−1soil, respectively. When C2H2was not present, the models predicted the experimentally observed initial flux of N2O if an 8 to 10 h lag in N2O reductase activity was included in the models. The best model for describing N2O fluxes in these experiments used differential rates of Michaelis‐Menten reduction without NO−3and nitrite (NO−2) inhibition of N2O reduction. Experimental techniques and parameter characterization, however, need considerable refinement. Independent measurements are needed to quantify relationships between reaction order and kinetic parameters. Still, given the general agreement between observed and predicted fluxes, there can be little doubt that the reaction‐diffusion models are essential to a better understanding of denitrification.

The interaction of fairy rings of Lycopodium tristachyumPursh. with the soil which they invade was examined by measurement of various soil enzymatic activities and extractable soil organic matter. The activities of cellulase, xylanase, inulinase, α‐galactosidase, invertase, peroxidase, chitinase, and polygalacturonase were enhanced in soil under the rings compared with soil just outside the rings. The activity of urease was lower under the ring while the activity of β‐glucosidase was unaffected. The amount of nitrogen, hexose, and phenolics extracted by 0.01MCaCl2during autoclaving was enhanced in soil under the ring. The level of reducing substances extracted by dilute buffer and the optical density of buffered extracts were similarly elevated. Extractable lipid, humic acid, and β‐humus were independent of soil location. Significant correlations between some readily extractable organic components and the activities of chitinase, invertase, xylanase, and α‐galactosidase in the soil were observed.

Lycopodium species (L. tristachyum, L. clavatum, and L. complanatum) sometimes occur as fairy rings—dense annuli of plants, 1 to 1.5 m wide, that grow radially outward at a rate of 20 to 50 cm/year and die within. The impact of these fairy rings on soil organic matter was investigated through studies of soil respiration and selected enzymatic activities. Respiration was enhanced in the soil under lycopodium rings compared with soil either outside or inside the rings. The activities of phosphatase, protease, dehydrogenase, catalase, polyphenol oxidase, amylase, and dextrinase were found to be independent of soil location. However, significant increases in cellulase, invertase, polygalacturonase, and peroxidase activities were observed in the soil under lycopodium rings. A model based on the infection of the lycopodium plant by its endophytic fungus and subsequent peroxidative degradation of soil organic matter is presented to explain both the increases in enzymatic activities and nutrient availability under lycopodium fairy rings.

Methods used for analysis of soil microbial biomass N and C are limited in precision and are time consuming. A method involving direct combustion of evaporated soil extracts was developed for use with an automated nitrogen and carbon analyzer (ANCA). The objectives of this study were to: (i) evaluate the usefulness of ANCA determination of microbial C and N, and (ii) ascertain whether the microbial C isotope ratios determined by the ANCA method would reflect C contributions from actively growing crops of wheat (Triticum aestivumL.) and maize (Zea maysL.) differing in C isotope ratio. Cropped and fallow soils were sampled at planting, anthesis, and maturity. Field‐moist soils were fumigated with chloroform and extracted with 0.05 MK2SO4for the ANCA method and with 0.5 MK2SO4for Kjeldahl analysis. Small volumes of the 0.05 MK2SO4extracts were evaporated on cone‐shaped tin disks that were analyzed using combustion at 1700°C and mass spectrometry. Reproducible values for C, N, and δ13C were obtained with less effort than that typically expended for Kjeldahl N analysis of similar extracts. Temporal changes in microbial δ13C occurred in both cropped and fallow soils during a single growing season. At maturity of the maize crop, an estimated 23% of the soil microbial C was derived from the plant material of the current maize crop. Carbon contribution from the wheat crop to the soil microbial biomass was not detected. Further refinements in the ANCA method may make the procedure routinely usable for enhancing the understanding of chloroform labile C and N as indicators of microbial dynamics in the soil.

Using short-term assays under anaerobic conditions, we measured potential activities of enzymes responsible for N2O generation and reduction in freshly sampled soils. Mean capacities for N2O generation ranged from 20 to 26 kg N ha-1day-1for four mineral soils with no effect of site or crop. Mean values for N2O reduction were between 44 to 47 kg N ha-1for three of the soils, but no reduction activity occurred in a fourth cropped to alfalfa. Including glucose in the assay procedures had inconsistent effects on denitrifying activities, which were largely associated with the surface (0 to 15 cm) layer of mineral soils. In contrast, N2O generation activity was detected throughout an organic soil profile (to 80 cm), but N2O reductase activity was observed only close to the water table where NO3-levels were low. Exposure of freshly sampled soils to air for 24 h had no effect on N2O generation activity, but completely inhibited N2O reduction activity. We discuss the implications of these results in terms of denitrification and N2:N2O ratios under a fluctuating O2supply in the field.

British Aerospace Warton Unit is using several methods to reduce the makespan of aircraft manufacture. To illustrate the principles three production facilities, which use different approaches to achieve significant makespan reductions, are described.

It may be desirable to minimize dinitrogen (N2) fixation in alfalfa (Medicago saliva L.) when a source of inorganic nitrogen (N), such as manure, is readily available. Our objectives were to determine the N2 fixation response of eight alfalfa germplasms to inorganic N and to characterize plant-to-plant variation for this trait. Seed was sown in vermiculite and irrigated with nutrient solution in growth chambers. Herbage was removed at 71 d and treatments of 1, 3, 5, or 10 mM N were applied as 15N-depleted ammonium nitrate (NH4NO3). After 34 d of regrowth, herbage was removed and analyzed for dry mass, total N concentration, and N isotope ratio. Increased availability of inorganic N resulted in a linear increase in herbage weight, height, shoot number, and N concentration, and consistently decreased N2 fixation for all germplasms. Estimated N2 fixation was greater than zero at the highest rate of inorganic N, which we speculate was due, in part, to remobilized root and crown N, because nodules appeared to be nonfunctional. Across all treatments, N2 fixation correlated best with herbage N concentration, but there was no relationship between these variables within a given N treatment concentration. Significant variation in reliance on N2 fixation in the presence of inorganic N existed in all eight germplasms.

The creep and recovery behaviour of highly drawn polypropylene monofilaments has been studied over the temperature range 20 to 50° C. A range of samples was examined to identify the influence of draw ratio and molecular weight. It is concluded that the permanent flow creep arises from the presence of two thermally activated processes, one of which relates to the a-relaxation process and is associated with the crystalline regions of the polymer, and the second with the molecular network.

To determine the effect of flooding of Pahokee muck (a drained, cultivated Histosol) on nitrous oxide emissions from the soil, we measured field N2O fluxes and N2O produced in soil samples incubated under controlled laboratory conditions. During the first 5 days of flooding of a field that had previously been cropped to sweet corn (Zea maysL. rugosa), the NO3--N levels declined from 68 to <0.1 microgram nitrogen per cubic centimeter. Similarly, the N2O flux decreased from 174 g N/ha/d prior to flooding to approximately 0 after flooding. Comparing the flux values and the N2O concentrations in the flood water suggested that the flooded field may have acted as a sink for atmospheric N2O. In laboratory-incubated samples of the preflood and flooded soils, the potential denitrification rates increased from 16.2 μg N/cm3/day prior to flooding to 31.2 μg N/cm3/d after flooding. Whereas N2O was the major product of denitrification in soil samples collected prior to flooding, very little N2O accumulated in samples collected from the flooded field. Nitrous oxide was readily reduced in the flooded soil in the presence of NO3--N and NO2--N concentrations of 100 and 3 mg/liter, respectively.

The nutrient content of drainage water from Histosols located in New York was monitored from June 1975 through July 1977. Continuous flow records and nutrient concentration data obtained from daily composite samples were used to calculate annual nutrient outputs which ranged from 0.6 to 30.7 kg/ha for PO4−‐P, 39.2 to 87.5 kg/ha for NO3−‐N, and <1.0 to 1.9 kg/ha for NH4+‐N. Nutrient concentrations in the drainage water increased with increasing flow, so that the greatest output of nutrients was during late winter and spring high‐flow events. Maximum observed concentrations were 35 mg/liter for NO3−‐N and 10 mg/liter for PO43−‐P. The amount of N lost in drainage water was similar at all sites and was about 10% of that mineralized; the remainder was presumed to be denitrified. The fiftyfold variability in phosphorus output appeared to be related to interactions within the soil profile rather than fertilizer practices, although these probably contributed to the generally high levels found. It was concluded that fertilizer nitrogen additions were unlikely to affect the quantity of NO3−leached. The study showed that organic soils can contribute to N and P in land runoff in much greater proportions than indicated by their area.

The C2H2‐block method was used to measure denitrification in a maize (Zea maysL.) field over the 85‐d period between sidedressing with N fertilizer and harvest. Measurement locations were changed weekly in order to avoid problems associated with microbial utilization of C2H2and inhibition of nitrification. Nitrous oxide (N2O) fluxes were measured both with and without C2H2addition to soil. Without C2H2addition to soil, 0.3 kg N ha−1was evolved from both unfertilized and Ca(NO3)2treated soil, whereas 2.5 kg N ha−1was evolved from urea treated soil. This difference was attributed to formation of N2O during nitrification of NH+4liberated from urea. With C2H2addition to soil, 1.6, 2.0, and 2.4 kg N ha−1were evolved as the result of denitrification in the zero N, Ca(NO3)2, and urea treated sites, respectively. Total gaseous N loss from a particular N treatment was approximated by adding together the N2O‐N loss with and without C2H2addition to soil. The gaseous N loss associated with fertilizer addition was <3% of that applied. The ratio of N2/N2O evolved without C2H2addition to soil was estimated to be in the range of 4:1 to 7:1 for the zero N and Ca(NO3)2treatments and about 1:1 for the urea treatment. Denitrification was responsible for at least 80% of the measured gaseous N loss from the zero N and Ca(NO3)2treatments. About equal amounts of gaseous N loss from the urea treatment occurred via denitrification and during nitrification of liberated NH+4.

The effect of complexing agents on Fe mobility was investigated using a simulated root‐soil system that consisted of 0.24‐mm o.d. cellulose fibers embedded in a clay‐agar matrix. Complexing agents diffused into the clay‐agar matrix from a solution flowing through the fibers and their effect on Fe flux to the fiber surface was determined by following Fe concentration in the effluent solution from the fibers. Experiments with the chelating agents ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine di‐(o‐hydroxyphenylacetic acid) (EDDHA), and ethylene glycol‐bis‐(2‐amino‐ethylether) tetraacetic acid (EGTA) demonstrated that solubilization of Fe qualitatively followed patterns predicted from known thermodynamic stability constant‐pH relationships. The concentration of Fe in the fibers 24 h after introduction of either EDTA, DTPA, or EDDHA was increased from close to 0 to 30 to 100 g Fe L−1, whereas EGTA had no measurable effect on Fe solubility. The measured fluxes of Fe were compared with calculations based on diffusion and reaction. An equilibrium model, where the complexing agent was assumed to equilibrate instantaneously with the soil (reaction rate constant Kr= 1), predicted concentrations of Fe 103times greater than those observed. A first‐order kinetic model, which was solved by numerical methods, gave results similar to those found experimentally when Krwas on the order of 10−7. The partial success of the thermodynamic stability constant approach was reconciled with the kinetic model by considering Krto combine both kinetic and equilibrium factors.

Gaseous N loss via denitrification can be measured with static flux chambers when acetylene (C2H2) is used to block nitrous oxide (N2) reduction. This paper describes a method for the introduction of C2H2at low concentrations into the soil by diffusion. The method utilizes an above‐ground manifold connected to diffusion tubes inserted in the soil and C2H2flows through the manifold at a rate of 0.33 mL s−1. Acetylene levels in the soil atmosphere within the flux chamber site ranged from 0.16 to 2.07 mol m−3, and the apparatus did not alter CO2fluxes as measured by a static chamber method.

The quantities of N mineralized when columns of Histosols were incubated at field capacity for periods up to 28 days corresponded to 500‐600 kg N/ha per year without correction for N lost by denitrification. An absorption train utilizing molecular sieve 5Å to collect N2O was used in denitrification experiments. Under an argon stream, 52‐53% of the added NO3‐‐N was recovered as N2O, whereas the maximum concentration of N2O accumulating in the headspace of closed vessels amounted to 65% of the added NO3‐‐N. The quantity of N2O either collected or accumulating in a headspace was reduced to 15‐41% of the NO3‐‐N denitrified when a second addition of NO3‐was made to the soils. Denitrification occurred in both drained and flooded soil columns amended with NO3‐. The N2O recovered ranged from 2.5‐9% and 9‐19% of the NO3‐‐N denitrified in the drained and flooded columns, respectively. From 78‐98% of the N2O was recovered in leachate from the flooded columns and the corresponding range for the drained columns was 11‐52%.

Technologies to reduce net emissions of carbon dioxide, methane and nitrous oxide within the agriculture sector were reviewed to estimate the global potential for mitigation of these radiatively active greenhouse gases. Our estimates of the potential reduction of radiative forcing by the agricultural sector range from 1.15-3.3 Gt C equivalents per year. Of the total potential reduction, approximately 32% could result from reduction in CO2emissions, 42% of carbon offsets by biofuel production on 15% of existing croplands, 16% from reduced CH4emissions and 10% from reduced emissions of N2O. Agriculture encompasses large regional differences in management practices and rates of potential adoption of mitigation practices. Acceptability of mitigation options will depend on the extent to which sustainable production will be achieved or maintained and benefits will accrue to farmers. Technologies such as no-till farming and strategic fertilizer placement and timing are now being adopted for reasons other than concern for climate change issues.

To understand nutritional rickets in Bangladesh better, 14 rachitic and 13 'unaffected' children were evaluated. Seventy per cent of children with active rickets had no evidence of either vitamin D deficiency or familial rickets. Rickets in Bangladesh is probably related to calcium deficiency. Abnormalities in 'unaffected' children suggest that subclinical calcium insufficiency is common.

Potential changes in the concentration of nitrous oxide (N2O) in the atmosphere have sparked considerable interest because of the proposed role of N2O in regulating stratospheric ozone levels, and in contributing to the atmospheric greenhouse effect. A substantial portion of the atmospheric N2O is thought to result from microbial transformations of inorganic forms of nitrogen in soils; N2O is an intermediate in denitrification (reduction of NO−3to N2) and is formed during nitrification (oxidation of NH+4to NO−3) in soils, although the mechanism is unclear. Several models have predicted that input of nitrogen into cropland, either from commercial fertilizers or N-fixing leguminous crops, could sufficiently increase emissions of N2O from soils to deplete stratospheric ozone levels1–3and raise average world temperatures4. We report here N2O emissions from mineral and organic soil sites in New York and from organic soil sites in the Florida Everglades Agricultural Area.

A procedure was developed for storing the N2O in 50‐mL air samples on activated molecular‐sieve type 5A in 60‐mL serum bottles. The procedure was equally effective for N2O concentrations of 1 and 10 µL · L−1and storage times up to 6 weeks. Blank values for sieves stored 3 to 5 months after activation ranged from about 0.04 ± 0.002 to 0.05 ± 0.005 µL · L−1. Allowing freshly activated sieves to cool in air before capping the bottles increased blank values and variability to unacceptable levels. Nitrous oxide fluxes from soil > 10 g N · ha−1· d−1could be reliably determined when the storage procedure was used in conjunction with a chamber method for N2O flux measurement.

Alcohols, carbonyl compounds, and fatty acids were formed in two glucose-amended soils incubated under argon, but dimethylselenide was evolved under argon only from one, a selenium-rich clay, after the addition of selenite and glucose. Substantial quantities of dimethylselenide were released from the four soils tested when they were incubated with glucose and selenite in air. No dimethylselenide was produced in the selenium-rich clay soil in air if it received glucose but no selenite.

An enzyme preparation from 2,4-dichlorophenoxyacetate-grown Arthrobactersp. converted cis,cis-2,4-dichloromuconate to chloromaleylacetate. The enzyme lactonizing the dichloromuconate to yield 2-chloro-4-carboxymethylene but-2-enolide was separated from the butenolide-delactonizing enzyme.