Number Of Sampling Locations Research Articles

Low-cost automated GPS, electrical conductivity and temperature sensing device (EC + T Track) and Android platform for water quality monitoring campaigns

Environmental and water quality monitoring are of utmost interest in a context where land use changes, uncontrolled agricultural practices, human settlements, tourism and other activities affect a watershed and condition the usage of their surface waters. Such is the case of Mar Menor lagoon in Southeast of Spain, where the EU H2020 SMARTLAGOON project stands and is implementing an intelligent environmental infrastructure and modelling that will let the construction of a digital twin of the lagoon. Performing environmental monitoring is expensive and the number of sampling locations is typically limited by the budget. For this reason, we have developed a low-cost monitoring system that can be integrated in a small-sized buoy and attached to fishing and recreational boats allowing citizens to gather water quality information – i.e. electrical conductivity and temperature – with the use of their smartphones. The usage of such devices leads to key stakeholder engagement and citizen science activities that could enrich and ease the data gathering process.

Hypothesis tests with functional data for surface quality change detection in surface finishing processes

This work is concerned with providing a principled decision process for stopping or tool-changing in a surface finishing process. The decision process is supposed to work for products of non-flat geometry. The solution is based on conducting hypothesis testing on the bearing area curves from two consecutive stages of a surface finishing process. In each stage, the bearing area curves, which are in fact the nonparametric quantile curves representing the surface roughness, are extracted from surface profile measurements at a number of sampling locations on the surface of the products. The hypothesis test of these curves informs the decision makers whether there is a change in surface quality induced by the current finishing action. When such change is detected, the current action is deemed effective and should thus continue, while when no change is detected, the effectiveness of the current action is then called into question, signaling possibly some change in the course of action. Application of the hypothesis testing-based decision procedure to both spherical and flat surfaces demonstrates the effectiveness and benefit of the proposed method and confirms its geometry-agnostic nature.

Rapid Biomonitoring of Heavy Metals in Polluted Sites Using Xenoassay®-Metal

Long-term water contamination, including heavy metals, may harm the reputation of the location. Because of this, it is necessary to do regular water quality checks. In light of the high expense of instrument monitoring, biomonitoring based on enzymes is rapidly gaining popularity around the world. For the purpose of this investigation, a molybdenum-reducing enzyme from the Serratia marcescens strain DRY6 that is sensitive to the heavy metals was used to build a quick inhibitory enzyme assay. The bacterium's molybdenum-reducing activity is extremely vulnerable to heavy metals. With the help of the established assay, heavy metals were detected in water samples collected in Malacca, Penang, and Perak. A number of sampling locations in Penang were found to be inhibiting enzyme activity, while all sampling locations in Malacca and Penang were confirmed to be free of high heavy metal concentrations. The Malaysian Department of Environment has set a maximum permissible limit for the suppression of Mo-reducing enzyme activity in Penang. Detection of heavy metals can be done in less than ten min at room temperature. The entire procedure takes less than 20 min. a first screening procedure or even a near real-time method for routine monitoring of heavy metals, assay is quick and straightforward.

Chromium content in fish and rice and its effect on public health along the downstream Opak River, Bantul District, Indonesia

Abstract. Rahardjo D, Djumanto, Prasetyaningsih A, Laoli B, Manusiwa WS. 2021. Chromium content in fish and rice and its effect on public health along the downstream Opak River, Bantul District, Indonesia. Intl J Bonorowo Wetlands 11: 69-74. The activities of the leather home industry are overgrowing, causing the liquid waste flowing into the river also to increase so that the threat to the river ecosystem and river water users also increases. This study aimed to determine the concentration of chromium in environmental components, agricultural commodities, fisheries, and the risk to public health. Sampling was carried out from February to August 2020 in irrigation canals and rice fields using the Opak River flow. The number of sampling locations is determined at six stations. At each station, samples of water, sediment samples, and fish, and samples of rice were collected. All samples were analyzed using Atomic Absorption Spectrophotometry (AAS). The results showed that chromium metal is found in solid or mineral compounds with other elements. The highest concentration was found in rice plants with an average of 1.0105-6.2870 mg/kg, followed by rice fields (1.2062 mg/kg), river sediments (0.7126), fish (0.3799-0.8489), irrigation water (0.2393 mg/L), and the lowest were found in river water (0.0188 mg/L). The Tolerable Maximum Intake of chromium in tilapia meat was 3.0271 kg/week, and Spotted barb meat was 1.3546 kg/week. The daily intake of chromium in rice ranged from 18.475 to 28.733 (mg/kg BW/day). Hazard quotient (HQ) level of consumption of chromium-contaminated rice ranged from 4.618-7.183. The HQ value at all research sites exceeds the safe value for health set by World Health Organization (WHO), namely HQ<1.

Efficient Sample Location Selection for Query Zone in Geo-Social Networks

While promoting a business or activity in geo-social networks, the geographical distance between its location and users is critical. Therefore, the problem of Distance-Aware Influence Maximization (DAIM) has been investigated recently. The efficiency of DAIM heavily relies on the sample location selection. Specifically, the online seeding performance is sensitive to the distance between the promoted location and its nearest sample location, and the offline precomputation performance is sensitive to the number of sample locations. However, there is no work to fully study the problem of sample location selection for DAIM in geo-social networks. To do this, we first formalize the problem under a reasonable assumption that a promoted location always adheres to the distribution of users (query zone). Then, we propose two efficient location sampling approaches based on facility location analysis, which is one of the most well-studied areas of operations research, and these two approaches are denoted by Facility Location based Sampling (FLS) and Conditional Facility Location Based Sampling (CFLS), respectively. FLS conducts one-time sample location selection, and CFLS extends the one-time sample location selection to a continuous process, so that an online advertising service can be started immediately without sampling a lot of locations. Our experimental results on two real datasets demonstrate the effectiveness and efficiency of the proposed methods. Specifically, both FLS and CFLS can achieve better performance than the existing sampling methods for the DAIM problem, and CFLS can initialize the online advertising service in a matter of seconds and achieve better objective distance than FLS after sampling a large number of sample locations.

Agent-based models reveal limits of mark-release-recapture estimates for the rare butterfly, Bhutanitis thaidina (Lepidoptera: Papilionidae).

Insect diversity and abundance are in drastic decline worldwide, but quantifying insect populations to better conserve them is a difficult task. Mark-release-recapture (MRR) is widely used as an ecological indicator for insect populations, but the accuracy of MRR estimates can vary with factors such as spatial scale, sampling effort and models of inference. We conducted a 3-year MRR study of B. thaidina in Yanzigou valley, Mt. Gongga but failed to obtain sufficient data for a robust population estimate. This prompted us to integrate B. thaidina life history information to parameterize agent-based models and evaluate the conditions under which successful MRR studies could be conducted. We evaluated: (1) the performance of MRR models under different landscape types, and (2) the influence of experimental design on the accuracy and variance of MRR-based estimates. Our simulations revealed systematic underestimates of true population parameters by MRR models when sampling effort was insufficient. In a total of 2772 simulations, subjective decisions in sampling protocol (e.g., frequency, number of sampling locations, use of spatially explicit models, type of estimands) accounted for nearly half of the variation in estimates. We conclude that MRR-based estimates could be improved with the addition of more field-specific parameters.

Source of groundwater iron and manganese in Chandrapur district, central India

Groundwater sampling was carried out by grab sampling method from 36 sampling locations from the Chandrapur district in three seasons i.e. winter, summer, and post-monsoon. The samples were analysed for physicochemical parameters and heavy metals i.e. iron and manganese. Data obtained from the study area was interpreted by using multivariate statistical analysis i.e. principal component analysis, cluster analysis, correlation matrix and one way ANOVA to ascertain source apportionment of these two heavy metals. The results of the multivariate analysis revealed that iron and manganese both were associated with the lithogenic source. Groundwater irons concentration was higher when compared with manganese and at a number of sampling locations it was above the stipulated standard of BIS (Bureau of Indian Standards) (0.3 mg/L).

Sampling strategy optimization to increase statistical power in landscape genomics: A simulation‐based approach

An increasing number of studies are using landscape genomics to investigate local adaptation in wild and domestic populations. Implementation of this approach requires the sampling phase to consider the complexity of environmental settings and the burden of logistical constraints. These important aspects are often underestimated in the literature dedicated to sampling strategies. In this study, we computed simulated genomic data sets to run against actual environmental data in order to trial landscape genomics experiments under distinct sampling strategies. These strategies differed by design approach (to enhance environmental and/or geographical representativeness at study sites), number of sampling locations and sample sizes. We then evaluated how these elements affected statistical performances (power and false discoveries) under two antithetical demographic scenarios. Our results highlight the importance of selecting an appropriate sample size, which should be modified based on the demographic characteristics of the studied population. For species with limited dispersal, sample sizes above 200 units are generally sufficient to detect most adaptive signals, while in random mating populations this threshold should be increased to 400 units. Furthermore, we describe a design approach that maximizes both environmental and geographical representativeness of sampling sites and show how it systematically outperforms random or regular sampling schemes. Finally, we show that although having more sampling locations (between 40 and 50 sites) increase statistical power and reduce false discovery rate, similar results can be achieved with a moderate number of sites (20 sites). Overall, this study provides valuable guidelines for optimizing sampling strategies for landscape genomics experiments.

Pursuit of Optimal Design for Winter-Balance Surveys of Valley-Glacier Ablation Areas

Efficient collection of snow depth and density data is important in field surveys used to estimate the winter surface mass balance of glaciers. Simultaneously extensive, high resolution and accurate snow-depth measurements can be difficult to obtain, so optimization of measurement configuration and spacing is valuable in any survey design. Using in-situ data from the ablation areas of three glaciers in the St. Elias Mountains of Yukon, Canada, we consider six possible survey designs for snow-depth sampling and $N$=6--200+ sampling locations per glacier. For each design and number of sampling locations, we use a linear regression on topographic parameters to estimate winter balance at unsampled locations and compare these estimates with known values. Average errors decrease sharply with increasing sample size up to $N\approx$10--15, but reliable error reduction for any given sampling scheme requires significantly higher $N$. Lower errors are often, but not always, associated with sampling schemes that employ quasi-regular spacing. With both real- and synthetic data, the common centreline survey produces the poorest results overall. The optimal design often requires sampling near the glacier margin, even at low $N$. The unconventional ``hourglass'' design performed best of all designs tested when evaluated against known values of winter balance.

Radiation exposure of adrenal vein sampling: a German Multicenter Study

ObjectiveAdrenal vein sampling (AVS) represents the current diagnostic standard for subtype differentiation in primary aldosteronism (PA). However, AVS has its drawbacks. It is invasive, expensive, requires an experienced interventional radiologist and comes with radiation exposure. However, exact radiation exposure of patients undergoing AVS has never been examined.Design and methodsWe retrospectively analyzed radiation exposure of 656 AVS performed between 1999 and 2017 at four university hospitals. The primary outcomes were dose area product (DAP) and fluoroscopy time (FT). Consecutively the effective dose (ED) was approximately calculated.ResultsMedian DAP was found to be 32.5 Gy*cm2 (0.3–3181) and FT 18 min (0.3–184). The calculated ED was 6.4 mSv (0.1–636). Remarkably, values between participating centers highly varied: Median DAP ranged from 16 to 147 Gy*cm2, FT from 16 to 27 min, and ED from 3.2 to 29 mSv. As main reason for this variation, differences regarding AVS protocols between centers could be identified, such as number of sampling locations, frames per second and the use of digital subtraction angiographies.ConclusionThis first systematic assessment of radiation exposure in AVS not only shows fairly high values for patients, but also states notable differences among the centers. Thus, we not only recommend taking into account the risk of radiation exposure, when referring patients to undergo AVS, but also to establish improved standard operating procedures to prevent unnecessary radiation exposure.

Inferring ecological processes from population signatures: A simulation-based heuristic for the selection of sampling strategies

A good knowledge about species traits variability in relation to their environment is the cornerstone of landscape-oriented species management studies. One way to infer this relationship is to compare species signatures in space and time from field data with spatially explicit population dynamics models outputs. However, the inference robustness relies on the available field data, and thus on the quality of the underlying sampling strategy. Field sampling is constrained by several factors, such as the number of landscape replicates, possible number of temporal sessions and number of sample locations, that need to be accounted for prior to field sampling. We set and illustrate a heuristic method to answer the question of optimal sampling conditioned by these landscape-induced constraints. First we studied a real agricultural landscape to determine its mean properties in terms of configuration and composition. The real landscape properties were used as constraints in a landscape model to generate a collection of landscapes with similar properties. On the other hand, we formulated population dynamics models (hereafter noted Process Models (PM)) carrying competing hypotheses about two ecological processes—population growth and dispersal—in relation to spatial covariates for Pterostichus melanarius, a carabid species involved in pest regulation. We simulated these spatially explicit models and extracted their sampling-dependent signatures, i.e. metrics computed on different population samples. We defined a sampling design quality as its ability to capture the contrasts between the PM signatures, summarised by the performance of a classification procedure. The most relevant sampling design was selected on the basis of classification performance and in situ feasibility. Finally we explored the effects of the a priori ecological hypotheses quality on classification performances, through a sensitivity analysis of the PM parameters. While some improvements remain to be achieved before being fully operational for landscape ecologists, our framework contributes to bringing closer sampling theory and its application on the field. It endorses the use of landscape modelling to design sampling prior to field experiment to bring out the best from sampled data.

Space-Time Sampling for Network Observability

Abstract We will investigate under what conditions taking coarse samples from a network will contain the same information as a finer set of samples. Our goal is to estimate the initial state of a linear network of subsystems, which are distributed in a spatial domain, from noisy measurements. We develop a framework to produce feasible sets of spatio-temporal samples for the estimation problem, which essentially have a non-uniform space-time sampling pattern. If the number of sampling locations is comparable to the size of the network, the sampling pattern will have a high degree of redundancy. For these cases, using an efficient algorithm, we present a method for finding a feasible subset of samples that have a sparser space-time sampling pattern. It is shown that spatial samples can be traded for time samples: choosing to sample from a smaller set of subsystems must be compensated by taking more frequent time samples from those subsystems. Furthermore, we apply the Kadison-Singer paving solution to sparsify a feasible redundant sampling strategy with guaranteed estimation bounds. We support our theoretical findings via several numerical examples.

Repeated Blood Collection from Tail Vein of Non-Anesthetized Rats with a Vacuum Blood Collection System

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the tail vein is thin so that it is sometimes hard to puncture. In addition, the tail vein has low blood flow and requires a long sampling time to get sufficient blood. The present report describes a simple blood sampling method, the vacuum blood collection method, which is usually used to obtain blood samples from patients, here used for non-anesthetized rats. The 22 G butterfly needle tip was inserted into one of the lateral tail veins approximately 2-3 cm from the tip of the tail at an angle of approximately 20°, and blood was collected in the vacuum collection tube by inserting the rubber end of the butterfly needle into the vacuum blood collection tube. The present experimental results show that the success rate was 95% in the experimental group and 90% in the beginner group. The success rate and puncture times were similar between two groups. The sampling duration was significantly shorter in the experimental group compared to beginner group. In conclusion, this vacuum blood collection method for sequential blood sampling from the tail vein of non- anesthetized rats is feasible and easy-to-learn, which might serve as a reliable alternative to other conventionally used blood sampling techniques for rats.

Repeated Blood Collection from Tail Vein of Non-Anesthetized Rats with a Vacuum Blood Collection System.

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the tail vein is thin so that it is sometimes hard to puncture. In addition, the tail vein has low blood flow and requires a long sampling time to get sufficient blood. The present report describes a simple blood sampling method, the vacuum blood collection method, which is usually used to obtain blood samples from patients, here used for non-anesthetized rats. The 22 G butterfly needle tip was inserted into one of the lateral tail veins approximately 2-3 cm from the tip of the tail at an angle of approximately 20°, and blood was collected in the vacuum collection tube by inserting the rubber end of the butterfly needle into the vacuum blood collection tube. The present experimental results show that the success rate was 95% in the experimental group and 90% in the beginner group. The success rate and puncture times were similar between two groups. The sampling duration was significantly shorter in the experimental group compared to beginner group. In conclusion, this vacuum blood collection method for sequential blood sampling from the tail vein of non- anesthetized rats is feasible and easy-to-learn, which might serve as a reliable alternative to other conventionally used blood sampling techniques for rats.

‘Catch me if you can’: Evaluating the population size in the presence of a spatial pattern

Many biological and ecological problems require accurate evaluation of the total population size. We discuss a sampling procedure used for evaluation of the population abundance from information collected on a grid of spatial sampling locations. It is shown in the paper how insufficient information about the spatial population density obtained on a coarse sampling grid affects the accuracy of evaluation. The insufficient information is collected because of inadequate spatial resolution of the population density on coarse grids and this is especially true when a heterogeneous spatial population is sampled. It is argued in the paper that the evaluation error is a random variable on coarse sampling grids because of the uncertainty in sampling spatial data and a probabilistic approach should be employed in the evaluation procedure. We also show that there exists a threshold number of sampling locations on a regular sampling grid where we can guarantee desired accuracy of evaluation. Information about the threshold number of sampling locations allows one to reconcile the probabilistic approach based on the assumption about randomness of sampling data with the deterministic approach based on the requirement that spatial data are collected only once as the sampling procedure cannot be repeated under the same conditions.

Development of an effective sampling strategy for ammonia, temperature and relative humidity measurement during sheep transport by ship

Ammonia, high temperature and high humidity have adverse effects on animals during long distance livestock export from Australia to the Middle East, but none of these is effectively measured currently. On the basis of data maps obtained on two voyages of live sheep export, this study determined sampling strategies for ammonia, temperature and humidity measurement on the vessel. The difference between predicted high and low ammonia sites on the shipment could be detected with approximately 5 measurement sites of each. Margins of error were determined, which suggested that dry bulb temperature could be measured with 6–8 measurement sites, but even 20 measurement sites were not sufficient to measure relative humidity. For the vessel recorded, considerably more ammonia measurement sites are required on closed decks than on open decks, with less variation for temperature measurement. The number of pens measured contributed more to the variance of ammonia and temperature measurement than the number of sampling locations within each pen on open decks. This study highlights the importance of a suitable sampling strategy to measure ammonia, temperature and relative humidity on board ship during live export.

Automatic Mapping of Monitoring Data

This paper presents an approach, based on universal kriging, for automatic mapping of monitoring data. The performance of the mapping approach is tested on two datasets containing daily mean gamma dose rates in Germany reported by means of the national automatic monitoring network (IMIS). In the second dataset an accidental release of radioactivity in the environment was simulated in the South-Western corner of the monitored area. The approach has a tendency to smooth the actual data values, and therefore it underestimates extreme values, as seen in the second dataset. However, it is capable of identifying a release of radioactivity provided that the number of sampling locations is sufficiently high. Consequently, we believe that a combination of applying the presented mapping approach and the physical knowledge of the transport processes of radioactivity should be used to predict the extreme values.

Assessment of Hydrochemical Characteristics of Groundwater for Drinking and Agricultural Purposes along the Coastal Areas of Chennai City, India

Groundwater samples from 18 locations were collected between December 2008 and March 2009 in the coastal areas of Chennai city along the Buckingham canal in Tamil Nadu, India. The quality of groundwater in this area has been analysed for drinking purposes by comparing the physical and chemical parameters with WHO standards. Further, the suitability of groundwater in this region for agriculture was evaluated based on sodium adsorption ratio and percent sodium. The present study reveals that quality of groundwater is found to be unsuitable for consumption in a number of sample locations. For irrigational purposes, the groundwater quality is suitable in few places.

Refinement of the supercontinent cycle with Hf, Nd and Sr isotopes

The combined use of Hf, Nd and Sr isotopes is more useful in understanding the supercontinent cycle than the use of only Hf isotopic data from detrital zircons. Sr and Nd seawater isotopes, although not as precise as ɛNd and ɛHf distributions, also record input from ocean ridge systems. Unlike detrital zircons where sources cannot be precisely located because of crustal recycling, both the location and tectonic setting often can be constrained for whole-rock Nd isotopic data. Furthermore, primary zircon sources may not reside on the same continent as derivative detrital zircons due to supercontinent breakup and assembly. Common to all of the isotopic studies are geographic sampling biases reflecting outcrop distributions, river system sampling, or geologists, and these may be responsible for most of the decorrelation observed between isotopic systems. Distributions between 3.5 and 2 Ga based on ɛHf median values of four detrital zircon databases as well as our compiled ɛNd database are noisy but uniformly distributed in time, whereas data between 2 and 1 Ga data are more tightly clustered with smaller variations. Grouped age peaks suggest that both isotopic systems are sampling similar types of orogens. Only after 1 Ga and before 3.5 Ga do we see wide variations and significant disagreement between databases, which may partially reflect variations in both the number of sample locations and the number of samples per location.External and internal orogens show similar patterns in ɛNd and ɛHf with age suggesting that both juvenile and reworked crustal components are produced in both types of orogens with similar proportions. However, both types of orogens clearly produce more juvenile isotopic signatures in retreating mode than in advancing mode. Many secular changes in ɛHf and ɛNd distributions correlate with the supercontinent cycle. Although supercontinent breakup is correlated with short-lived decreasing ɛHf and ɛNd (≤100 Myr) for most supercontinents, there is no isotopic evidence for the breakup of the Paleoproterozoic supercontinent Nuna. Assembly of supercontinents by extroversion is recorded by decreasing ɛNd in granitoids and metasediments and decreasing ɛHf in zircons, attesting to the role of crustal reworking in external orogens in advancing mode. As expected, seawater Sr isotopes increase and seawater Nd isotopes decrease during supercontinent assembly by extroversion. Pangea is the only supercontinent that has a clear isotopic record of introversion assembly, during which median ɛNd and ɛHf rise rapidly for ≤100 Myr. Although expected to increase, radiogenic seawater Sr decreases (and seawater Nd increases) during assembly of Pangea, a feature that may be caused by juvenile input into the oceans from new ocean ridges and external orogens in retreating mode. The fact that a probable onset of plate tectonics around 3 Ga is not recorded in isotopic distributions may be due the existence of widespread felsic crust formed prior to the onset of plate tectonics in a stagnant lid tectonic regime, as supported by Nd and Hf model ages.

Comparison of measured and calculated concrete and rebar specific activity during decommissioning of the Dalhousie SLOWPOKE-2 reactor

Following the defuelling and dismantling of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) in 2011, the reactor pool concrete and rebar were sampled to support the unconditional free release of the material such that the facility could be classified for unrestricted use. A detailed MCNP5 model of the critical core assembly was simulated to calculate the thermal, intermediate and fast neutron flux profile below the reactor pool floor. The neutron fluxes were used to calculate the specific activity of significant radionuclides in the concrete and rebar. The calculated specific activity and consequently the calculated neutron fluxes were validated at a number of sample locations. The calculated concrete and rebar specific activity were found to be in good agreement with the measured specific activity at the sample locations. The unrestricted use of the facility was granted through the approval of the licence to abandon the facility in August 2011.