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The aim of this study was to assess soil quality and identify main indicators and their critical limits as a function of relative rice yield in northern Iran. In present study, 60 topsoil (0–30 cm) samples were collected and 18 physical, chemical, and biological soil attributes were measured and analyzed. Based on the mean rice yield obtained from sampling sites, paddy fields were divided into fields with low (< 4.5 t ha−1) and high (≥ 4.5 t ha−1) productivity. Using the principal component analysis (PCA), among 18 soil indicators, 4 indicators were selected as the minimum dataset (MDS) including soil organic carbon (OC), urease activity, bulk density (BD), and available Zn (AZn). The upper and lower limits of MDS indicators and soil quality index (SQI) were defined using scatterplot. The results showed that the mean SQI of high productivity fields (0.95) was significantly higher than that in low productivity fields (0.77). The upper and lower limits for soil OC were 3.5 and 1.0 (g 100 g−1), urease activity 84 and 43 (μg NH4 g soil−1 2 h−1), BD 1.84 and 1.60 (g cm−3), and AZn 2.0 and 0.6 (mg kg−1), respectively. The soil quality assessment using SQI accounted for 52% of the rice yield variation. Thus, management practices and mitigation of soil limiting factors should be comprehensively investigated to ensure sustainable rice production in the paddy fields of northern Iran. [ABSTRACT FROM AUTHOR]

Background: Since the spread of Severe Acute Respiratory Syndrom Corona Virus 2 (SARS-CoV‑2) in Germany, intensive care beds have been kept free for patients suffering from Corona Virus Disease (COVID-19). Also, after the number of infections had declined, intensive care beds were kept free prophylactically; however, the percentage of beds reserved for COVID-19 differ in the individual federal states in Germany. The aim of this article is to define a necessary clearance quota of intensive beds for COVID-19 patients in Germany. An escalation and de-escalation scheme was created for rising and falling numbers of infected patients.Methods: Data from the COVID-19 resource board of the state of Baden-Württemberg, the daily situation report of the Robert Koch Institute (RKI), the register of COVID-19 intensive care beds of the German Interdisciplinary Association for Intensive Care and Emergency Medicine (DIVI) as well as the daily report of COVID-19 Baden-Württemberg from April to November 2020 were used for the calculation.Results: At the end of November 2020 approximately 13.5% of intensive care beds in Germany were used by COVID-19 patients. Of all persons tested positive for SARS-CoV‑2, 1.5% were admitted to an intensive care unit. The hospitalization rate was 6% and the mean age of infected persons was 43 years. Based on these numbers hospitals are recommended to keep 10% of intensive care beds available for COVID-19 patients in the case of less than 35 new infections/100,000 in the catchment area, 20% should be kept free in case of an advanced warning level of 35 new infections/100,000 inhabitants and 30% for a critical limit of 50 new infections/100,000 inhabitants. Further internal hospital triggers, such as the occupancy of the intensive care beds with COVID-19 patients, should be considered.Conclusion: If the number of infections is low a general nationwide retention rate of more than 10% of intensive care beds for COVID-19 patients is not justified. Locally increasing numbers of infections require a local dynamic approach. If the number of infections increases, the free holding capacity should be increased according to a step by step concept in close coordination with the local health authorities and other internal hospital triggers. In order not to overwhelm hospital capacities in the event of local outbreaks, a corresponding relocation concept should be considered at an early stage. [ABSTRACT FROM AUTHOR]

Northeastern China has long-term densely tilled soils that supply approximately 20% of the annual total national grains. There are very few reports on the agricultural soil quality subjecting to the predatory tillage. Here, the soil quality index (SQI) of a brunisolic soil was calculated using the minimum data set (MDS) and integrated quality index (IQI). The topsoil layer was divided into plow layer (11.9 ± 1.9 cm) and plow pan (11.4 ± 2.6 cm) in fields of high yields (HYB), medium yields (MYB), and low yields (LYB). Our results showed that the MDS of the topsoil layer only contained chemical indicators. The bulk density (BD), as one of the most important soil quality indicators, was found of no significant differences in the topsoil layers. In different layers (i.e., the topsoil layer, plow layer, and plow pan), the value of SQI presented a consistent tendency of HYB > MYB > LYB (p < 0.05). The correlation between SQI and yield was higher in the plow layer (0.60) and plow pan (0.63) than the topsoil layer (0.47). This further verified the reasonability of using soil stratification for SQI calculation. Our findings indicate the potential of using soil quality assessments to examine soil productivity (e.g., fertilizer deficiency) in crop lands with soil stratification. [ABSTRACT FROM AUTHOR]

Low-level measurements of Po using alpha spectrometry with a Po tracer have been conducted at the Environmental Research Institute of the Supervising Scientist ( eriss) for many years, on samples with a range of activity concentrations spanning several orders of magnitude. These samples originated from a wide range of research and monitoring projects, and included a wide variety of traditional foods consumed by the indigenous population in Australia's Northern Territory. Assessment of instrument blank and analyte blank data from these measurements collected over a period of 8 years was conducted. Instrumental blank data for Po and Po generally followed a normal distribution, whereas analyte blank data for Po followed a lognormal distribution. Instrumental blank data for Po indicated an increasing trend, indicative of a low level of polonium volatilisation from prepared sources. Lower limits of detection, including the critical limit, detection limit and quantification limit have been calculated. The critical limit ranges from 12 to 37 counts per day. Detection and quantification limits range from 0.18 to 0.33 mBq and 2.3 to 3.6 mBq for a 4-day count, with an assumed mean chemical recovery of 53 %. These limits are relatively high for alpha spectrometric techniques due to the high variability of the analyte blank signal and non-normal distribution for Po. Native plant species have relatively low activity concentrations of Po in their edible fruits and the amount of sample that should be used for analysis to ensure 90 % of fruit samples analysed reach the specified quantification limit was 11 g. [ABSTRACT FROM AUTHOR]

When a net count value is below the type 1 error critical limit it is customary to declare that the activity is “below the detection limit”. The content of this declaration is particularly impoverished, incapable for example of discriminating between a net measurement just below the critical limit, but positive, and a negative net measurement, two types of information that it is legitimate and intuitive to think do not have the same weight of information. In the case of a spectral measurement of 131mXe and 133mXe certain information is available according to the various X and gamma emissions, which might all be below their respective critical limits. We shall see that a Bayesian probabilistic approach can be used, without considering the critical limits, to obtain anti-correlated maximum likelihood values taking all the information into account jointly and to obtain powerful and pertinent information in the form of the absolute probability that the sample contains 131mXe and/or 133mXe, all possible activity values combined. Conversely, of course, this is used immediately to deduce the probability that the sample does not contain 131mXe and/or 133mXe. This information enables the customary critical limit to be ignored. [ABSTRACT FROM AUTHOR]

According to recent insight, the toxicity of metals in soils is better related to the free metal ion (FMI) activity in the soil solution than to the total metal concentration in soil. However, the determination of FMI activities in soil solution is a difficult and time-consuming task. An alternative is to use empirical equations (so called transfer functions (TFs)) that relate FMI activity in solution to the reactive metal concentration in the solid phase and to soil properties (pH and organic matter content). Here we test the applicability of two sets of TF for Cd and Pb using independent data from a wide range of soil types and regions that are not represented in the datasets used to derive the TFs. From these soils, soil solution was extracted using four different methods. For all these extracts, FMI activities were calculated from total concentrations in solution using the speciation program WHAM VI. In some of the soils, Cd and Pb FMI activities were also measured using a Donnan membrane technique. Most of these FMI activities deviated from the TF predictions by less than one order of magnitude and were within the 95% confidence interval of the TFs, irrespective of the method used to extract soil solution. Predictability was higher for Pb than for Cd and differed also between the two TF sets. [ABSTRACT FROM AUTHOR]

The calculation of critical loads and their exceedance is one method to describe the vulnerability of forests to environmental stress caused by anthropogenic impact. Exceedance of critical loads for acidifying inputs and nitrogen was compared to different indicators of the soil and forest conditions in the German part of the extensive forest monitoring (ICP Forests/EU Level I), including more than 1,800 plots. In addition, an empirical relationship between the C/N ratio of the forest floor humus layer ( C/N Humus) and the estimated nitrogen output for ten plots of the intensive monitoring (ICP Forests/EU Level II) was established in order to estimate the potential nitrogen output on Level I plots dominated by Norway spruce. Regarding all tree species assessed, the exceedance of critical loads for nitrogen and sulphur is negatively correlated with pH and base saturation up to 30 cm soil depth. The sulphur deposition and the exceedance of critical loads are highly correlated with the sulphur content of leaves and needles, whereas the respective relations for nitrogen were lower. The crown condition was weakly positively related to the sulphur content in tree leaves and needles. For Norway spruce sites, high exceedance of critical loads for nitrogen and nitrogen deposition corresponded well with low C/N Humus. In regions with high nitrogen load and low C/N ratios in the humus layer, the calculated nitrogen output was high. The results support the concept of critical thresholds in that way that their exceedance can impair forest ecosystem functions like nitrogen retention. [ABSTRACT FROM AUTHOR]

The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP Waters) was established in July 1985 under the Executive Body of the Convention on Long-Range Transboundary Air Pollution (LRTAP). The main aim of the Programme is to assess, on a regional basis, the degree and geographical extent of acidification of surface waters. Dose/response relationship of acid deposition to aquatic invertebrates is discussed for different regions of Europe. The bases for the study are the occurrence of the most sensitive species in their geographical areas. Critical limit will vary depending on definition of acceptable damage level. To minimise this discussion we have used the presence of the most sensitive species for defining the critical limit. The study shows that critical limit of acid neutralisation capacity (ANC) vary depending on the typical fauna of sensitive species and their adaptations to the native water chemistry. In areas with different composition of sensitive species, different critical limit is suggested, varying from ANC < 20 µeq/L to ANC >50 µeq/L. [ABSTRACT FROM AUTHOR]

Critical loads have become a well-established part of the work programme of the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (CLRTAP). The linking of ecosystem response to deposition level is the central principal of the critical loads approach. For each ecosystem, a biological indicator is chosen, a suitable chemical criterion selected and a critical chemical limit assigned. The Bc:Al ratio is the most widely used chemical criterion for setting critical loads. However, critical loads based on this criterion are very sensitive to marine deposition. In regions which receive high depositions of marine-derived base cations, such as the Republic of Ireland (ROI) and the United Kingdom (UK), critical loads based on the Bc:Al criterion will inevitably be high. Therefore, it is proposed that critical loads are estimated using multiple chemical criteria with appropriate critical limits to protect the chosen biological indicators. The range of published chemical criteria have been applied to the ROI and the UK. The chemical criterion corresponding to the most sensitive critical load have been mapped and the contribution of each to the final maps investigated. The simulations indicate that the most sensitive criteria for setting critical loads are based on specifying critical H or Al concentrations. However, the choice of critical limits and model parameters will ultimately effect the critical loads. Therefore, it is important that appropriate critical limits are chosen to protect the biological indicator and receptor ecosystem from long-term damage. [ABSTRACT FROM AUTHOR]

The retransmission cut-off is not needed for a stable operation of slottedALOHA if the new packet generation rate is below a critical limit. Thethroughput never reaches its maximum value if the new packet generation rateis less than this critical limit irrespective of the number of transmissions.The maximum throughput is attained by adjusting the number of transmissions,pertaining to the new packet generation rate exceeding the critical limit.A complete analysis for the new packet generation rate with the properadjustment of the number of transmissions that maximize the channel throughputin a Rayleigh fading channel is executed. A stable operating region in termsof the packet rejection probability and the corresponding number oftransmissions is devised. [ABSTRACT FROM AUTHOR]