Field Water Supply Research Articles

An IoT and machine learning solutions for monitoring agricultural water quality: a robust framework

All living things, comprising animals, plants, and people require water to survive. The world is covered in water, just 1 percent of it is fresh and functional. The importance and value of freshwater have increased due to population growth and rising water demands. Approximately more than 70 percent of the world's freshwater is used for agriculture. Agricultural employees are the least productive, inefficient, and heavily subsidized water users in the world. They also utilize the most water overall. Irrigation consumes a considerable amount of water. The field's water supply needs to be safeguarded. A critical stage in estimating agricultural production is crop irrigation. The global shortage of fresh water is a serious issue, and it will only get worse in the years to come. Precision agriculture and intelligent irrigation are the only solutions that will solve the aforementioned issues. Smart irrigation systems and other modern technologies must be used to improve the quantity of high-quality water used for agricultural irrigation. Such a system has the potential to be quite accurate, but it requires data about the climate and water quality of the region where it will be used. This study examines the smart irrigation system using the Internet of Things (IoT) and cloud-based architecture. The water's temperature, pH, total dissolved solids (TDS), and turbidity are all measured by this device before the data is processed in a cloud using the range of machine learning (ML) approaches. Regarding water content limits, farmers are given accurate information. Farmers can increase production and water quality by using effective irrigation techniques. ML methods comprising support vector machines (SVM), random forests (RF), linear regression, Naive Bayes, and decision trees (DT) are used to categorize pre-processed data sets. Performance metrics like accuracy, precision, recall, and f1-score are used to calculate the performance of ML algorithms.

IoT Based Smart Agricultural System for Efficient Crop Growth

Population growth has made agriculture the most important growth sector in the world. The challenge in the agricultural industry right now is to improve the efficiency and quality of agriculture without regular physical monitoring to meet the rapidly increasing food demand. Along with population growth, climatic condition is also a major challenge in agriculture. The purpose of this study is to propose an internet-based smart agricultural model of things that uses clustering to deal with adverse conditions. This model uses different types of sensors for different purposes, such as soil moisture, barometric pressure, rainfall detection, and humidity sensors. The data is collected in the cloud and calculated automatically. Intelligent agriculture is automatically taken over by plant management, useful data collection and analysis. The purpose of this white paper is to implement the Internet of Things (IoT) to monitor humidity, soil conditions, temperature and field water supply, water levels, and climatic conditions. The IoT-based smart farming system envisioned in this report is integrated with a variety of sensors and a Wi-Fi module that produces live data feeds that can be accessed online. Keywords: Smart farming, IOT, Clustering, Sensors, Cloud.

A study on the vulnerability of field water supply using public groundwater wells as irrigation in drought-vulnerable areas with a focus on the Dangjin-si, Yesan-gun, Cheongyang-gun, and Goesan-gun regions in South Korea

A study on the vulnerability of field water supply using public groundwater wells as irrigation in drought-vulnerable areas with a focus on the Dangjin-si, Yesan-gun, Cheongyang-gun, and Goesan-gun regions in South Korea

ОЦЕНКА ОРГАНИЗАЦИИ РАБОТ ПО ОБОРУДОВАНИЮ ПУНКТА ПОЛЕВОГО ВОДОСНАБЖЕНИЯ

Purpose. The increase in number and scales of emergencies consequences, the complexity of the tasks for the solution of which rescue units must be ready requires predicting the results of planned actions and applying mathematical modeling methods to substantiate decisions. The use of mathematical models should help reveal the patterns of rescue units actions on improving the principles of their application, methods of fulfilling their support tasks. Analytical models make it possible to establish formula dependence between the conditions of the situation, the elements of the decision to be made and the effectiveness of the task performance according to the selected criterion. Statistical methods make it possible to more fully take into account the probabilistic nature of the simulated processes and they are most effective in cases when the analytical description of the simulated process presents great difficulties, or it is practically impossible due to significant uncertainty of the initial information. The best results can be obtained with the combined use of analytical and statistical models: the analytical model allows approximately figuring out the basic laws of the phenomenon, outlining its contours, and any further clarification can be obtained by statistical modeling. Therefore, the article discusses the use of the statistical test method for organizing implementation of first priority engineering tasks performed by rescue units. Methods. To obtain the results general scientific and special methods of scientific knowledge including analysis, synthesis, generalization were used; they were based on the provisions of systems theory, operations research, information theory and the method of statistical tests. Findings. A scientific and methodological approach is developed to improve the effectiveness of emergency rescue units use in the emergency area on the example of their equipping a field water supply point. Research application field. The results are applicable to substantiate a set of means for performing tasks and operations by rescue teams. Conclusions. The developed scientific and methodological approach makes it possible to assess the effectiveness of organizing the tasks performance in the emergency area by emergency rescue teams in general, and, in particular, equipping the field water supply point, and it also serves as a basis for improving the work of management bodies at all levels.

МОДЕЛИРОВАНИЕ ОРГАНИЗАЦИИ РАБОТ ПО ОБОРУДОВАНИЮ ПУНКТА ПОЛЕВОГО ВОДОСНАБЖЕНИЯ

Purpose. The increase in number and scales of emergencies consequences, the complexity of the tasks for the solution of which rescue units must be ready requires predicting the results of planned actions and applying mathematical modeling methods to substantiate decisions. The use of mathematical models should help reveal the patterns of rescue units actions on improving the principles of their application, methods of fulfilling their support tasks. Analytical models make it possible to establish formula dependence between the conditions of the situation, the elements of the decision to be made and the effectiveness of the task performance according to the selected criterion. Statistical methods make it possible to more fully take into account the probabilistic nature of the simulated processes and they are most effective in cases when the analytical description of the simulated process presents great difficulties, or it is practically impossible due to significant uncertainty of the initial information. The best results can be obtained with the combined use of analytical and statistical models: the analytical model allows approximately figuring out the basic laws of the phenomenon, outlining its contours, and any further clarification can be obtained by statistical modeling. Therefore, the article discusses the use of the statistical test method for organizing implementation of first priority engineering tasks performed by rescue units. Methods. To obtain the results general scientific and special methods of scientific knowledge including analysis, synthesis, generalization were used; they were based on the provisions of systems theory, operations research, information theory and the method of statistical tests. Findings. A scientific and methodological approach is developed to improve the effectiveness of emergency rescue units use in the emergency area on the example of their equipping a field water supply point. Research application field. The results are applicable to substantiate a set of means for performing tasks and operations by rescue teams. Conclusions. The developed scientific and methodological approach makes it possible to assess the effectiveness of organizing the tasks performance in the emergency area by emergency rescue teams in general, and, in particular, equipping the field water supply point, and it also serves as a basis for improving the work of management bodies at all levels.

Faktor-Faktor Yang Mempengaruhi Kesediaan Petani Dalam Membayar Jasa Lingkungan Air Padi Sawah

The Air Sarap Sub-watershed is a sub-watershed located in Samadua Subdistrict, South Aceh Regency, where water from the Air Sarap Sub-watershed has been used for domestic household needs and rice field water supply needs. The impact of forest encroachment and land conversion on upstream sub-watersheds causes droughts in the dry season and floods in the rainy season, where floods that come in the rainy season destroyed most community infrastructure, such as houses, roads, bridges and agricultural irrigation which provide supply community wetland water. This research aims to analyze and determine factors that influence rice field farmers in paying for environmental services in the Air Sarap Sub-watershed which has been functioning as a water supplier in lowland rice farming

Comparison of drought stress indices in beech forests: a modelling study

Abstract: Two drought stress indices were applied to managed as well as old-growth beech forests and gaps for the 2001 to 2013 period to aid in the development of an efficient tool for field water supply diagnosis. The relative extractable soil water (REW), which was calculated from the soil water content in the root zone, and the transpiration index (TI), calculated as the ratio between the actual and potential transpiration were used. Both indices were calculated on a daily basis using the water balance model BROOK90, which was fitted and tested using measured data on throughfall and soil water content. A sensitivity analysis apportioned to the input parameters of the drought stress indices was conducted to assess uncertainty. Both drought stress indices showed the greatest drought stress in the years 2009, 2003 and 2011, as also indicated by the Standardized Precipitation Evapotranspiration Index (SPEI) at the nearest meteorological station. However, drought stress intensity and duration differed between the indices and study sites. Greater water supply stress was shown in the forests than the gaps. Furthermore, the agreement among the indices was smaller for gaps compared with forests, which implies that careful index selection is needed when comparing water supply stresses in different stages of forest stand development. Due to the low amount of input data required and the parameters that can be measured with relative ease in the field, REW might be an efficient tool for field water supply diagnosis when analyzing the drought stresses of similar forest types and at unique stages of development. REW satisfactorily indicated drought stress in forests but to a lesser extent in gaps. TI demonstrated more consistent differences in drought stress between forests and gaps and therefore proved to be the appropriate index for a detailed analysis of drought stress variation between different stages of forest stand development. However, due to a greater number of required input data and more demanding parameters, TI appears to be a more complex tool than REW for field water supply diagnosis in forests.

A permafrost test on intact gneiss rock

Changes in permafrost conditions in high mountain rocks have increased the risk of dangerous instabilities. Ice segregation within the rock mass has been interpreted as one of the mechanisms involved in high mountain bedrock degradation. A long term laboratory test on a cube of intact gneiss has been designed to reproduce field temperature gradients and water supply conditions. Test results demonstrate that ice crystallization in a permafrost fringe (T=0°C to −3°C) leads to the formation of continuous ice-filled cracks which explain the loss of rock continuity and the observed rock failures. A coupled thermo-hydro-mechanical model which incorporates the thermodynamics of ice-water mixtures has been used to reproduce test results. The model, which follows existing formulations for unsaturated porous media, was capable of capturing the main observations derived from the experiment. Calculated tensile stresses are close to the gneiss tensile strength. The analysis performed is a step forward in understanding field observations and in the application of computational tools to real cases.

Crop Yield and Water Requirement Relationships for Major Irrigated Crops in Southern Alberta

Water supplies available for irrigation in southern Alberta are limited. A study was conducted in southern Alberta to develop crop yield and evapotranspiration (ETc) relationships for major irrigated crops based on current maximum potential crop yield data and improved methods for determination of crop evapotranspiration. Production functions for crop yield and the field water supply, which includes irrigation at 80% efficiency, effective precipitation, and stored soil moisture depletion, were subsequently determined. These empirical relationships may be used by water managers, economists, and producers to examine the economic implications of crop yield reductions from water stress due to limited water supplies, less than optimum (deficit) irrigation management, or variation in evaporative demand from year to year in different agro-climatic areas of southern Alberta. Potential yield estimates for different scenarios may be used with relevant economic information to determine optimum water use for irrigation.

Studying the interactive effect of potassium application and individual field crops on root penetration under drought condition

In this study, interactive effects of different potassium application and water restrict on: root penetration at Iran. The experimental unit had designed by achieved treatment in factorial on the basis completely randomized block design with three replications. Certain factors including potassium and non-potassium applications (0 and 200 kg/ha), certain field crops (maize, sorghum and millet) and water supply were studied. In this study crops water supply was determined by indicated irrigation conditions by keeping leaf relative water content (RWC) > 95% (non-drought stress condition or irrigation conditions) and drought condition by RWC = 60 - 70%. We noticed, however K fertilizer significantly increased the root penetration of plants. Although the non-drought stress treatment significantly increased root penetration and highest root penetration of maize was achieved under irrigation conditions (non-drought), but the highest roots penetration of sorghum and millet were indicated under the drought condition. Whereas K application persist less damaging of drought stress result and it enabled plant to significantly grew its root and penetrating along soil depth under the drought condition. Our finding may give applicable advice to farmers and agricultural researchers for management and concern on fertilizer strategy and carefully estimate soil potassium supply within arid or semi arid regions as most challengeable issues of environmental safety. Key words: Potassium fertilizer, drought stress, root penetration, maize, sorghum, millet.

Field water supply:yield relationships of grain sorghum grown in three USA Southern Great Plains soils

Field water supply (FWS) combines the three sources of water used by a crop for evapotranspiration (ET), and consists of available soil water at planting (ASWP), rainfall, and irrigation. Examining the grain yield and FWS relationship ( Y g:FWS) may provide insight into the reported variability in crop water production functions such as water productivity (WP) and irrigation water productivity (IWP). Since water is most productive when entirely consumed in ET, diversion of FWS into non-ET losses such as drainage and excessive soil water evaporation results in declines in WP and IWP. The objective of this experiment was to examine the Y g:FWS and Y g:ET relationships of grain sorghum grown under a range of irrigation treatments (0, 25, 50, and 100% replacement of ET), beginning soil water contents, evaporative demands, in the Amarillo, Pullman, and Ulysses soils of the Great Plains. The purpose was to determine the amount of FWS beyond which declines in WP and IWP began to occur due to non-ET losses as indicated by a change in the slope and intercept of the Y g:FWS and Y g:ET relationships. Large amounts of non-ET irrigation application losses occurred in the finer-textured soils in the T-100 irrigation treatment. In both years, the T-100 irrigation application amounts and ASWP resulted in a FWS ranging from 750 to 870 mm which exceeded the maximum ET requirement of 530–630 mm and which reduced WP and IWP. Piecewise regression analysis of the Y g:FWS and Y g:ET relationships for the crops in the Pullman and Ulysses soils identified the knot point, or change in slope and intercept, in the FWS where both WP and IWP tended to be optimized. This was about 500 mm in both soils, and involved the utilization of about 250 mm in ASWP, irrigation applications averaging about 250 mm, and about 60–130 mm remaining in the soil at harvest. For the coarser-textured Amarillo soil, the yield response to increasing FWS was linear, because non-ET application losses such as drainage gradually increased with the irrigation application amount. The linear Y g response in the sandy Amarillo soil and the piecewise Y g responses in the clay and silt loams of the Pullman and Ulysses soils to FWS also reflected the difference in water-holding capacities of the soils that affected the amount of available water as irrigation increased. Irrigating without considering FWS resulted in non-ET irrigation application losses and declines in WP and IWP.

Toposequential effects on water balance and productivity in rainfed lowland rice ecosystem in Southern Laos

In the Mekong region, most paddies in rainfed lowland rice ( Oryza sativa L.) lie in a sequence on gentle sloping land, and grain yield (GY) often depends on the toposequence position. There is, however, lack of information on toposequential effects on field water supply in rainfed lowland rice and how that influences GY. A total of eight field experiments were carried out on sandy, coarse-textured soils in Southern Laos (Champassak Province and Savannakhet Province) over three wet seasons (2000–2002). Components of the water balance, including downward and lateral water movement ( D and L, respectively), were quantified at three different positions along toposequences (top, middle and bottom). GY, days-to-flower (DTF) and rainfall were measured, and the water productivity (WP) was determined. In most experiments, standing water disappeared first in the top position and gradually in lower positions. This was associated with the observation that when there was standing water in the field, the higher position had larger D in both the provinces and also larger L in Champassak Province. However, in one experiment, water loss appeared later in the higher position, as the result of lower L, apparently due to some water inputs other than rainfall occurring at this position. Despite larger D plus L at the top position, seasonal sum of D and L were not much affected by the toposequence position, as the daily rate of D plus L became minimal when the standing water was lost earlier in the top position. Lower GY was associated with earlier disappearance of standing water from the field. Relatively low GY was expected in the top toposequence position. This was clearly shown in the toposequence of Phonthong, Champassak Province, as the timing of standing water disappearance relative to flowering was earlier in the top position. Variation in GY across the toposequence positions was coupled with the WP variation, and both GY and WP tended to decline with increased DTF. Therefore, variation in productivity of rainfed lowland rice across toposequence positions depends mainly on the field water status around flowering time.

Lentil production under supplemental irrigation in a Mediterranean environment

Lentil is a major winter-sown legume crop grown in the Mediterranean region, and has considerable importance as food, feed, and fodder. The crop’s high water demands coincide with the end of the rainy season. Thus, lentil often experiences considerable drought stress during reproductive development, which reduces yields. Limited supplemental irrigation (SI) can boost and stabilize productivity. The objective of this study was to elucidate the effect of limited irrigation and early sowing on yield and water productivity (WP) of lentil. An experiment was carried out over four cropping seasons (1996–2000) at ICARDA’s main station at Tel Hadya (Aleppo, northern Syria) where mean annual rainfall is 330 mm. A lentil cultivar (ILL 5883) was grown in rotation with wheat. The experiment included three sowing dates (early: mid November; normal: late December to mid January; and late: late January to mid February) and four levels of SI (full SI, 2/3 SI, 1/3 SI, and no SI). The results indicated that lentil grain and biomass yield increased with increased SI. Mean grain yield of 1.04 t ha −1 under rainfed conditions increased to 1.42 at 1/3 SI, 1.69 at 2/3 SI, and 1.81 t ha −1 at full SI, while mean water productivity was 0.44 kg grain m −3 water when rainfed, 0.54 at 1/3 SI, 0.6 at 2/3 SI, and 0.58 kg m −3 at full SI. Overall mean biomass production was 4.27 (rainfed), 5.35 (1/3 SI), 6.00 (2/3 SI), and 6.2 t ha −1 (full SI). The study’s results indicated that the 2/3 SI level gives the maximum water productivity for both grain and biomass under SI. Early sowing increased lentil biomass production by 0.47 and 1.56 t ha −1 over normal and late sowing dates. However, the highest grain yield of 1.60 t ha −1 was obtained at the normal sowing date. Grain water productivity with SI, however, increased when seeds were sown late in the season. Biomass water productivity, by contrast, increased with the earliness of sowing date—1.79 (late), 1.97 (normal), and 2.05 kg m −3 (early). Sowing date had the greatest impact on crop response under rainfed conditions. Finally, production functions relating lentil yield with field water supply under supplemental and rainfed conditions were proposed.

Profitable and energy-efficient rice (Oryza sativa)-based cropping systems in Northern Telangana of Andhra Pradesh

A field experiment was conducted at Regional Agricultural Research Station, Jagtial, during rainy (kharif) and winter (rabr) seasons of 1996-97 to 1998-99 on red sandy-loam soils, to find out profitable and energy-efficient rice (Oryza sativa L.)-based cropping sequences among different cropping sequences, viz., rice-maize (Zea mays L.), rice-sunflower (Helianthus annuus L.), rice-groundnut (Arachis hypogaea L.), rice-blackgram (Phaseolus mungo L.), rice-greengram (Phaseolus radiatus L.), rice-soybean [Glycine m a (L.) Merr.], rice-ln- dian mustard [Brassica juncea (L.) Czernj. & Cosson] and rice-rice. Of the 8 cropping sequences, rice-rice, rice- maize and rice-sunflower cropping sequences gave significantly higher rice-equivalent yield (1 1,616, 11,553 and 10,868 kg/ha respectively) and gross returns (Rs 51,745, 51,464 and 48,2911ha respectively). Though field water supply was higher to rice-rice cropping sequence (2,800 mm), the water-use efficiency was lowest (4.15 kg/mm). Similarly, rice-rice cropping sequence also required higher energy input (75,036 MJIha) but the energy efficiency and energy productivity were lowest (4.2 and 155 g1MJ). However, net returns and benefit : cost ratio were higher with rice-maize (Rs 21,8841ha; 1.74) and rice-sunflower (Rs 21,3211ha; 1.79) cropping sequences. Similarly, these cropping sequences also recorded higher energy-use efficiency (6.4 and 5.1 respectively), en- ergy productivity (227 and 238 g1MJ respectively) and water-use efficiency (7.22 and 7.50 kglmm respectively) and were more sustainable than rice-rice and other rice-based cropping sequences.

Modeling water balance components and irrigation efficiencies in relation to water requirements for double-cropping systems

This paper describes the estimation of total water requirements as well as reservoir releases required to replenish the water deficit for double cropping of rice. A water balance equation is derived and the performance of a project is analyzed. The water balance components were modeled without calibration, and compared with measured data whenever possible. The potential evapotranspiration ET p were modeled for monthly time series using Penman–Monteith model [Monteith, J.L.,1965. Symp. Soc. Exp. Biol. 19, 205–234]. To estimate surface runoff, the proportion of elementary areas that are saturated were described by a spatial distribution function, considering the average total existing water (TEW) of both cropping seasons from 1991 to 1997. The monthly rainfalls (1971–1997) of 53 uniformly distributed rainfall stations were averaged and the rainfall considered uniform over the whole area. The effective meteorological input M e was considered positive to produce runoff. The variation of the soil suction head and hydraulic conductivity with moisture content, studied by Brooks and Corey [Brooks, R.H., Corey, A.T., 1964. Hydraulic properties of porous media. Hydrology Paper No. 3, Colorado State University, Fort Collins, CO] was applied in the Green–Ampt model [Green, W.H., Ampt, G.A., 1911. J. Agric. Sci. 4 (1), 1–24] to estimate infiltration. The performance of a farm irrigation system is, in general, evaluated by the efficiency of the system. The nonlinear Muskingum–Cunge method [Cunge, J.A., 1969. J. Hydraulics Res., Int. Assoc. Hydraulics Res. 7 (2), 205–230] was applied as a distributed channel routing technique to calculate the conveyance losses from the study reservoir (Pedu Reservoir) to the end of the main canal, a total reach of about 108 km. The mean conveyance efficiency from the Pedu dam to the Pelubang barrage (67 km reach) was found to be 66%, while the same from the Pedu dam to the end of the main canals was found to be 59%. Using Central Canal Right Bank Drain (CCRBD) A1 block data as reported by Batumalai and Nassir [Batumalai, R., Nassir, M.A.,1986. Effective water utilization with on farm terminal infrastructure. Northern Regional Water Seminar, Alor Setar, Malaysia], the distribution efficiency was determined to be 94%. The water use efficiency was estimated using MADA’s field water supply data. The overall project efficiency for the main and off-seasons were calculated separately and found to be 18 and 32%, respectively. The total water requirements for rice in the main and off-seasons were determined and the amounts of water needed to release from the reservoir to meet the crop water deficit for double cropping were estimated to be 1385 million cubic meters (MCM).

Seasonal Evaluation of Surge Flow Irrigation for Corn

SURGE flow irrigation of graded furrows was success-fully managed under field conditions to change a conventional 12-h steady flow set, 400-m (Vi-mile) field length, to a 24-h set by using the same field water supply to irrigate a large area per set. The surge flow treatment resulted in reduced total water application during seven irrigations from 1,180 to 814 mm (46.5 to 32.0 in.), reduced water intake from 992 to 733 mm (39.1 to 28.8 in.), reduced tailwater runoff from 189 to 82 mm (7.4 to 3.2 in.), and reduced estimated deep profile wetting below the root zone from 101 to 36 mm (4.6 to 1.4 in.) on moderately permeable Olton clay loam. Surge flow reduced both seasonal water use and grain yields by 6% and did not affect seasonal water use efficiency for grain production. The surge flow effect on reducing water intake of a surface soil loosened by tillage (32%) was almost double the average effect attained (17%) after consolidation of the surface soil by previous irrigation. The results indicate that surge flow irrigation can be managed successfully to reduce excessive water application in graded furrow systems.

Infectious diseases and field water supply and sanitation among migrant farm workers.

An audit for fecal-related symptoms was performed on clinic patient charts of 936 migrant farm workers without access to water and sanitation facilities in the work fields and on an urban poor population of 8,968 patients. Migrants displayed a clinic utilization rate for diarrhea 20 times higher than that of the urban poor; similar findings for other enteric disease symptoms were documented. The data suggest that a water and sanitation standard mandating facilities in the work field for farm workers would reduce the incidence of fecal-related disease.

Soil Survey Interpretations from Water Retention Data: II. Assessment of Soil Capability Ratings and Crop Performance Indices

AbstractA water retention model developed for Ontario soils is used to estimate the preseason plant‐available moisture‐holding capacity (Θva) of the soil root zone in equilibrium with a phreatic surface and the air‐filled porosity (ε) of the surface 30 cm. Preliminary soil capability class ratings are then assessed from a set of regional guidelines based on class intervals of Θva and ε. Crop performance indices are determined for capability classes 1 to 5 inclusive using a statistical corn productivity model which relates long‐term mean grain corn yields in Ontario to a seasonal soil moisture deficit or surplus. Total seasonal field water supply is budgeted against potential crop evapotranspiration to estimate the extent to which plant water stress from excess or deficit soil water availability limits the attainment of regional agro‐climatic potential yields. Advantages in using a water retention model as a basis for agronomic interpretations of soil survey data for land evaluation purposes are discussed.

Army Field Water Supply Developments

Army Field Water Supply Developments Hayse H. Black CopyRight*Presented before the Engineering Section of the American Public Health Association at the Seventy-second Annual Meeting in New York, N. Y., October 13, 1943. https://doi.org/10.2105/AJPH.34.7.697 Published Online: August 29, 2011

A BIBLIOGRAPHY OF FIELD WATER SUPPLY

A BIBLIOGRAPHY OF FIELD WATER SUPPLY Jack J. Hinman, Jr. CopyRight https://doi.org/10.2105/AJPH.8.9.668 Published Online: August 30, 2011