Extractive Titrimetric Determination of Hg(II), Cu(II) & Ag(I) Using Lead Diethyldithiocarbamate

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How Algorithmic Confounding in Recommendation Systems Increases Homogeneity and Decreases Utility

Recommendation systems are ubiquitous and impact many domains; they have the potential to influence product consumption, individuals' perceptions of the world, and life-altering decisions. These systems are often evaluated or trained with data from users already exposed to algorithmic recommendations; this creates a pernicious feedback loop. Using simulations, we demonstrate how using data confounded in this way homogenizes user behavior without increasing utility

Optical properties of Yb3+ doped ZnO/MgO nanocomposites

[EN] Yb3þ doped ZnO/MgO nanocomposite were prepared by combustion synthesis method. The samples were further heated to 1000 °C to improve their crystallinity and photoluminescent efficiency. The concentrations of Yb3þ and Mg2þ were varied between 1–2% and 5–70% respectively in prepared samples. The nano-powders were characterized by Scanning Electron Microscopy and X-ray Diffraction for morphology and structural determination. XRD studies have revealed the wurtzite structure for MgxZn1"xO for Mg concentrations below 30%. Higher concentrations of Mg results in Yb3þ doped ZnO/ MgO nanocomposite containing three phases; the wurzite hexagonal phase typical of ZnO, the cubic phase of MgO and a small amount of cubic Yb2O3 phase. As expected, the amount of cubic phase in nanopowders increased with the increase of Mg concentration in ZnO. The crystallite size of ZnO/MgO composites decreased from 55 nm to 30 nm with increase of Mg content. SEM images of Yb3þ doped ZnO/MgO nanocomposite with higher Mg content (450%) showed clearly distinct hexagonal and cubical shaped nano-particles. Photoluminescent emission showed a broad band in the range (435 nm to 700 nm). Pure ZnO nano-phosphor showed an emission peak around 545 nm, which is blue shifted with Mg content. The photoluminescence intensity increased with increase of Mg content in ZnO and it became maximum with 30% Mg concentration. Time resolved decay curves of photoluminescence indicated decay time in microsecond time scaleThis work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R), Generalitat Valenciana (PROMETEUS-II/2014/044) and the European Commission through NanoCIS project (FP7-PEOPLE-2010-IRSES ref. 269279).Marí, B.; Singh, KC.; Verma, N.; Jindal, J. (2016). Optical properties of Yb3+ doped ZnO/MgO nanocomposites. Ceramics International. 42(11):13018-13023. https://doi.org/10.1016/j.ceramint.2016.05.079S1301813023421

Identifying individuals with virologic failure after initiating effective antiretroviral therapy: The surprising value of mean corpuscular hemoglobin in a cross-sectional study

<p>Abstract</p> <p>Objective</p> <p>Recent studies have shown that the current guidelines suggesting immunologic monitoring to determine response to highly active antiretroviral therapy (HAART) are inadequate. We assessed whether routinely collected clinical markers could improve prediction of concurrent HIV RNA levels.</p> <p>Methods</p> <p>We included individuals followed within the Johns Hopkins HIV Clinical Cohort who initiated antiretroviral therapy and had concurrent HIV RNA and biomarker measurements ≥4 months after HAART. A two tiered approach to determine whether clinical markers could improve prediction included: 1) identification of predictors of HIV RNA levels >500 copies/ml and 2) construction and validation of a prediction model.</p> <p>Results</p> <p>Three markers (mean corpuscular hemoglobin [MCH], CD4, and change in percent CD4 from pre-HAART levels) in addition to the change in MCH from pre-HAART levels contained the most predictive information for identifying an HIV RNA >500 copies/ml. However, MCH and change in MCH were the two most predictive followed by CD4 and change in percent CD4. The logistic prediction model in the validation data had an area under the receiver operating characteristic curve of 0.85, and a sensitivity and specificity of 0.74 (95% CI: 0.69-0.79) and 0.89 (95% CI: 0.86-0.91), respectively.</p> <p>Conclusions</p> <p>Immunologic criteria have been shown to be a poor guideline for identifying individuals with high HIV RNA levels. MCH and change in MCH were the strongest predictors of HIV RNA levels >500. When combined with CD4 and percent CD4 as covariates in a model, a high level of discrimination between those with and without HIV RNA levels >500 was obtained. These data suggest an unexplored relationship between HIV RNA and MCH.</p

Advancing fruiting season in Annona cv. Arka Sahan through pruning

Annona cultivar ‘Arka Sahan’, an inter-specific hybrid of Annona atemoya × A. squamosacomes to harvest during August-September under mild tropical climate, which coincides with monsoon rains resulting in poor fruit quality and high susceptibility to anthracnose and fruit fly. An attempt was made to advance the fruiting in this hybrid through pruning during 2016- 17 and 2017-18. The effect of three pruning levels (25, 50 and 75% of previous season’s growth) at five different times (60, 75, 90, 105 and 120 days after final harvest of previous crop) on flowering and fruiting were compared. Early sprouting, flowering and fruit harvest were recorded in trees pruned to 75% of the past season’s growth in both the years. Earliest fruits were harvested 271 (3rd week of June) and 268 (2nd week of June) days after pruning in trees pruned during first week of October in 2016-17 and 2017-18 respectively (P&lt;0.05).Bigger fruits with lesser seeds per 100 g of pulp (P&lt;0.05) were harvested from trees pruned to 75% and 25% levels in the first and second year, respectively, irrespective of pruning time. Tree canopy following pruning at 75%level recorded higher light interception and photosynthetic rate (P&lt;0.05). Pruning time and levels significantly influenced the biochemical constituents of leaf and shoot. The fruiting in cultivar ‘Arka Sahan’ could be thus advanced by 8-9 weeks to June from the normal season of August-September with comparable or better fruit quality by pruning 75% of the last season’s growth during October

Overview of Intercalibration of Satellite Instruments

Intercalibration of satellite instruments is critical for detection and quantification of changes in the Earth’s environment, weather forecasting, understanding climate processes, and monitoring climate and land cover change. These applications use data from many satellites; for the data to be interoperable, the instruments must be cross-calibrated. To meet the stringent needs of such applications, instruments must provide reliable, accurate, and consistent measurements over time. Robust techniques are required to ensure that observations from different instruments can be normalized to a common scale that the community agrees on. The long-term reliability of this process needs to be sustained in accordance with established reference standards and best practices. Furthermore, establishing physical meaning to the information through robust Système International d’unités traceable calibration and validation (Cal/Val) is essential to fully understand the parameters under observation. The processes of calibration, correction, stabilitymonitoring, and quality assurance need to be underpinned and evidenced by comparison with “peer instruments” and, ideally, highly calibrated in-orbit reference instruments. Intercalibration between instruments is a central pillar of the Cal/Val strategies of many national and international satellite remote sensing organizations. Intercalibration techniques as outlined in this paper not only provide a practical means of identifying and correcting relative biases in radiometric calibration between instruments but also enable potential data gaps between measurement records in a critical time series to be bridged. Use of a robust set of internationally agreed upon and coordinated intercalibration techniques will lead to significant improvement in the consistency between satellite instruments and facilitate accurate monitoring of the Earth’s climate at uncertainty levels needed to detect and attribute the mechanisms of change. This paper summarizes the state-of-the-art of postlaunch radiometric calibration of remote sensing satellite instruments through intercalibration

Overview of Intercalibration of Satellite Instruments

Intercalibration of satellite instruments is critical for detection and quantification of changes in the Earth’s environment, weather forecasting, understanding climate processes, and monitoring climate and land cover change. These applications use data from many satellites; for the data to be interoperable, the instruments must be cross-calibrated. To meet the stringent needs of such applications, instruments must provide reliable, accurate, and consistent measurements over time. Robust techniques are required to ensure that observations from different instruments can be normalized to a common scale that the community agrees on. The long-term reliability of this process needs to be sustained in accordance with established reference standards and best practices. Furthermore, establishing physical meaning to the information through robust Système International d’unités traceable calibration and validation (Cal/Val) is essential to fully understand the parameters under observation. The processes of calibration, correction, stabilitymonitoring, and quality assurance need to be underpinned and evidenced by comparison with “peer instruments” and, ideally, highly calibrated in-orbit reference instruments. Intercalibration between instruments is a central pillar of the Cal/Val strategies of many national and international satellite remote sensing organizations. Intercalibration techniques as outlined in this paper not only provide a practical means of identifying and correcting relative biases in radiometric calibration between instruments but also enable potential data gaps between measurement records in a critical time series to be bridged. Use of a robust set of internationally agreed upon and coordinated intercalibration techniques will lead to significant improvement in the consistency between satellite instruments and facilitate accurate monitoring of the Earth’s climate at uncertainty levels needed to detect and attribute the mechanisms of change. This paper summarizes the state-of-the-art of postlaunch radiometric calibration of remote sensing satellite instruments through intercalibration

Assessment of the Spectral Stability of Libya 4, Libya 1, and Mauritania 2 Sites Using Earth Observing One Hyperion

The objective of this paper is to formulate a methodology to assess the spectral stability of the Libya 4, Libya 1, and Mauritania 2 pseudo-invariant calibration sites (PICS) using Earth Observing One (EO-1) Hyperion sensor. All the available Hyperion collections, downloaded from the Earth Explorer website, were utilized for the three PICS. In each site, a reference spectrum is selected at a specific day in the vicinity of the region of interest (ROI) defined by Committee on Earth Observation Satellites (CEOS). A series of ROIs are predefined in the along-track direction with 196 spectral top-of-atmosphere reflectance values in each ROI. Based on the reference ROI spectrum, the spectral stability of these ROIs is evaluated by average deviations (ADs) and spectral angle mapper (SAM) methods in the specific ranges of time and geo-spatial locations. Time and ROI location-dependent SAM and AD results are very stable within +/- 2 deg and +/-1.7% of 1sigma standard deviations. Consequently, the Libya 4, Mauritania 2, and Libya 1 CEOS selected PICS are spectrally stable targets within the time and spatial swath ranges of the Hyperion collections