Within-Plant Distribution of Two-Spotted Spider Mites, Tetranychus urticae Koch (Acari: Tetranychidae), on Strawberries: Decision of an Optimal Sampling Unit

It is known that two-spotted spider mite (Tetranychus urticae), a major pest of strawberry, is difficult to manage. This study was conducted to determine the optimal sampling unit to increase management efficiency of T. urticae in strawberries. The sampling unit was determined by characterizing within-strawberry distribution of T. urticae and by comparing coefficient of variation (CV) and correlation coefficient (r2) among potential sampling units. There was a significant (p < 0.05) difference in densities within a strawberry according to the leaf age. However, there was no significant difference in its density within a trifoliate leaf. More T. urticae were found on young-fully-opened (moderately old) leaves than on young and old ones. Moreover, these leaves had lower CV and r2 values than others. More specifically, optimal sampling units of T. urticae were fifth, fifth or sixth, and sixth oldest leaves for motiles (immatures and adults), all stages (motiles and eggs), and eggs, respectively. The required sampling number should be determined depending on the density. However, for management purposes, one and two leaflets would be acceptable for eggs and motiles, respectively. By using this small number of suitable sampling unit, the sampling and management for T. urticae in strawberries could be more efficient than before.

Experimental Estimation of Deviation Frequency within the Spectrum of Scintillations of the Carrier Phase of GNSS Signals

The term deviation frequency (fd) denotes the boundary between the variable part of the amplitude and phase scintillation spectrum and the part of uninformative noises. We suggested the concept of the “characteristic deviation frequency” during the observation period. The characteristic deviation frequency is defined as the most probable value of the deviation frequency under current local conditions. Our case study involved GPS, GLONASS, Galileo and SBAS data under quiet and weakly disturbed geomagnetic conditions (geomagnetic storm on 16 April 2021, Kpmax = 5, SYM-Hmin = −57 nT) at the mid-latitude GNSS station. Our results demonstrated that the deviation frequency for all signal components of GPS, GLONASS and Galileo varies within 15–22 Hz. The characteristic deviation frequency was 20 Hz for the mentioned GNSS signals. The SBAS differs from other systems: deviation frequency varies within 13–20 Hz. The characteristic deviation frequency is lower and equal to 18 Hz. We suggest the characteristic deviation frequency to determine the optimal sampling rate of the GNSS carrier phase data for the ionospheric studies. In turn, the deviation frequency can be considered as a promising index to estimate the boundary of non-variability of the ionosphere.

Convergence bounds for empirical nonlinear least-squares

We consider best approximation problems in a nonlinear subset [[EQUATION]] of a Banach space of functions [[EQUATION]] . The norm is assumed to be a generalization of the [[EQUATION]] -norm for which only a weighted Monte Carlo estimate [[EQUATION]] can be computed. The objective is to obtain an approximation [[EQUATION]] of an unknown function [[EQUATION]] by minimizing the empirical norm [[EQUATION]] . We consider this problem for general nonlinear subsets and establish error bounds for the empirical best approximation error. Our results are based on a restricted isometry property (RIP) which holds in probability and is independent of the nonlinear least squares setting. Several model classes are examined where analytical statements can be made about the RIP and the results are compared to existing sample complexity bounds from the literature. We find that for well-studied model classes our general bound is weaker but exhibits many of the same properties as these specialized bounds. Notably, we demonstrate the advantage of an optimal sampling density (as known for linear spaces) for sets of functions with sparse representations.

Single-site sampling versus multi-site sampling for blood cultures; A retrospective clinical study

Objectives The performance of blood cultures (BC) relies on optimal sampling. Sepsis guidelines do not specify which sampling protocol to use, but recommend two sets of BC bottles, each set containing one aerobic and one anaerobic bottle. For the single-site sampling (SSS) protocol, only one venipuncture is performed for all four bottles. The predominating multi-site sampling (MSS) protocol implies that BC bottles are collected from two separate venipuncture sites. The aim of this study was to compare SSS and MSS. Primary outcomes were number of BC sets collected, sample volume and diagnostic performance. Methods This was a retrospective clinical study comparing BC results in an emergency department before and after changing the sampling protocol to SSS from MSS. All BC samples were incubated in the BacT/ALERT BC system. Results The analysis included 5,248 patients before and 5,364 patients after the implementation of SSS. There was a significantly higher proportion of positive BCs sampled with SSS compared to MSS, 1,049/5,364 (19.56%) and 932/5,248 (17.76%) respectively ( P =0.018). This difference was due to a higher proportion of solitary BC sets (two BC bottles) in MSS. Analyzing only patients with the recommended four BC bottles, there was no difference in positivity. SSS had a higher proportion of BC bottles with the recommended sample volumes of 8-12 ml than MSS ( P <0.001). Conclusions Changing the sampling protocol to SSS from MSS resulted in higher positivity rates, higher sample volume and fewer solitary BC sets. These advantages of SSS should be considered in future sepsis guidelines.

Determination of zinc by atomic absorption in automobile tire rubber as a source of ecotoxicants in atmospheric air

Annotation. A methodology for determining zinc in tires (as a source of ecotoxicants in the atmospheric air) by atomic absorption with microwave pre-treatment as a product of motor vehicle wear in St. Petersburg was developed. In the article, the author gives different ways of sampling for testing. One of the rubber samples was taken from one area no larger than 5x5 cm on one tyre (first sampling option), the second sample was taken cumulatively from all tyre sides around its circumference (second sampling option). Tests of selected samples were carried out allowing conclusions to be drawn about the optimal sampling method. A comparative analysis has been made of the test results of samples taken by different methods from the car tyre surface. Based on the comparative analysis conclusions were made about the homogeneity of the tire composition. Various physical and chemical methods of sample preparation for the heavy metals determination are presented. In the course of the work the author selected the optimal conditions for sample preparation for testing allowing to obtain the maximum possible extraction of the analyte at the stage of sample preparation. The atomic absorption method was used to determine the zinc content in automobile tire samples. On the basis of the results obtained conclusions about the optimal sampling methods and sample preparation were made and the test conditions of the samples were optimized.

Determination of zinc by atomic absorption in automobile tire rubber as a source of ecotoxicants in atmospheric air

Annotation. A methodology for determining zinc in tires (as a source of ecotoxicants in the atmospheric air) by atomic absorption with microwave pre-treatment as a product of motor vehicle wear in St. Petersburg was developed. In the article, the author gives different ways of sampling for testing. One of the rubber samples was taken from one area no larger than 5x5 cm on one tyre (first sampling option), the second sample was taken cumulatively from all tyre sides around its circumference (second sampling option). Tests of selected samples were carried out allowing conclusions to be drawn about the optimal sampling method. A comparative analysis has been made of the test results of samples taken by different methods from the car tyre surface. Based on the comparative analysis conclusions were made about the homogeneity of the tire composition. Various physical and chemical methods of sample preparation for the heavy metals determination are presented. In the course of the work the author selected the optimal conditions for sample preparation for testing allowing to obtain the maximum possible extraction of the analyte at the stage of sample preparation. The atomic absorption method was used to determine the zinc content in automobile tire samples. On the basis of the results obtained conclusions about the optimal sampling methods and sample preparation were made and the test conditions of the samples were optimized.