scholarly journals OLCI A/B Tandem Phase Analysis, Part 2: Benefits of Sensors Harmonisation for Level 2 Products

2020 ◽  
Vol 12 (17) ◽  
pp. 2702 ◽  
Author(s):  
Nicolas Lamquin ◽  
Alexis Déru ◽  
Sébastien Clerc ◽  
Ludovic Bourg ◽  
Craig Donlon
Keyword(s):  
Phase Analysis ◽  
Temporal Stability ◽  
Ground Truth ◽  
Vicarious Calibration ◽  
Requirements Specifications ◽  
Level 1 ◽  
Cross Calibration ◽  
The Individual ◽  
The Impact ◽  
Level 2

This study is a follow-up of a full methodology for the homogenisation and harmonisation of the two Ocean and Land Colour Instrument (OLCI) payloads based on the tandem phase analysis. Sentinel-3B was manoeuvred into a tandem configuration with its operational twin Sentinel-3A already in orbit few weeks after its launch, which was followed by a short drift phase during which Sentinel-3B was progressively moved to a specific orbit phasing of 140° separation from the sentinel-3A. Harmonisation is performed at Level 1 for the radiometric alignment of the OLCI-A TOA radiances to the ones of OLCI-B, considering the slight spectral differences between the two instruments. The benefits of this harmonisation for the main Level 2 products are assessed in the present manuscript for both land and water products. The results validate such benefits showing accuracy between the two sensors after harmonisation better than the products requirements specifications. For the water processing branch, this accuracy opens a path toward an ensemble Sentinel-3 system vicarious calibration with ground-truth measurements. For land products, the tandem phase analysis is also an opportunity to demonstrate that the terrestrial chlorophyll index product requires improvements of the preliminary spectral adjustment of the red-edge channel at 709 nm. As comparisons from the measurements acquired over the tandem phase provides confidence in the alignment of the OLCI-A and OLCI-B series of products, preliminary analysis of the measurements acquired over the drift phase provides the first insights into the sensitivity of the processing algorithms to the geometry of acquisition as well as to calibration residuals of the OLCI field-of-view. As the harmonisation currently performs a radiometric alignment of OLCI-A to OLCI-B, the question of the reference sensor for operational implementation of the harmonisation raises concerns on the individual quality of the calibration of each sensor, notably their across-track consistency. Following the investigations performed at Level 1, where relatively strong calibration residuals are shown between the OLCI cameras and very similarly for both instruments; we discuss the impact of these residuals at L2 using an empirical correction and further conclude with the need to address these problematics with more attention in the future. We conclude with the extreme usefulness of the tandem phase analysis, presently for Level 2 products, and the need to further monitor the temporal stability of the cross-calibration of the OLCI payloads with a view to implementing their harmonisation at operational level.

scholarly journals Practical example for use of the supervised vicarious calibration (SVC) method on multisource hyperspectral imagery data – ValCalHyp airborne hyperspectral campaign under the EUFAR framework

2014 ◽  
Vol XL-7 ◽  
pp. 51-53
Author(s):  
A. Brook ◽  
E. Ben Dor
Keyword(s):  
Atmospheric Correction ◽  
Ground Truth ◽  
Critical Issue ◽  
Radiometric Calibration ◽  
Vicarious Calibration ◽  
Flight Direction ◽  
Novel Approach ◽  
Novel Method ◽  
General Goal ◽  
Cross Calibration

A novel approach for radiometric calibration and atmospheric correction of airborne hyperspectral (HRS) data, termed supervised vicarious calibration (SVC) was proposed by Brook and Ben-Dor in 2010. The present study was aimed at validating this SVC approach by simultaneously using several different airborne HSR sensors that acquired HSR data over several selected sites at the same time. The general goal of this study was to apply a cross-calibration approach to examine the capability and stability of the SVC method and to examine its validity. This paper reports the result of the multi sensors campaign took place over Salon de Provenance, France on behalf of the ValCalHyp project took place in 2011. The SVC method enabled the rectification of the radiometric drift of each sensor and improves their performance significantly. The flight direction of the SVC targets was found to be a critical issue for such correction and recommendations have been set for future utilization of this novel method. The results of the SVC method were examined by comparing ground-truth spectra of several selected validation targets with the image spectra as well as by comparing the classified water quality images generated from all sensors over selected water bodies.

scholarly journals Multi-level validation of the German physical activity barriers self-efficacy scale in a sample of female sixth-graders

2019 ◽  
Author(s):  
Joachim Bachner ◽  
David Joseph Sturm ◽  
Stephan Haug ◽  
Yolanda Demetriou
Keyword(s):  
Physical Activity ◽  
Internal Consistency ◽  
Self Efficacy ◽  
Sixth Graders ◽  
Individual Level ◽  
Class Level ◽  
Multi Level ◽  
Level 1 ◽  
The Individual ◽  
Level 2

Abstract Background The physical activity behaviour of the majority of children and adolescents is insufficient. Self-efficacy is regarded as one of the most important determinants able to enhance physical activity. The purpose of this study is to validate the German version of the physical activity barriers self-efficacy scale by means of a multi-level approach. Factorial validity, internal consistency and criterion validity were examined for the individual and the class level.Methods The final sample comprised 454 female sixth-graders of 33 classes. The original 8-item physical activity barriers self-efficacy scale was translated by a committee approach and pilot tested within the pretest procedure. To examine the factorial validity of the translated scale, a multi-level confirmatory factor analysis was conducted with the lavaan package in R. Internal consistency was estimated with the alpha function of the psych package. Criterion validity was examined by correlating self-efficacy with moderate-to-vigorous physical activity (MVPA) assessed with accelerometers.Results In contrast to previous validation studies, two-dimensional models fit the data better than uni-dimensional models. The best overall fit exhibited a 2x2-model, with two factors both on the individual and the class level (χ2 = 65.13, CFI = .985, TLI = .977, RMSEA = .046, SRMR = .033). The latent factors correlated highly on both levels (r = .87; r = .72). Every item loaded significantly on its respective factor on both levels. Internal consistency for the full scale and the first subscale was good on the individual level and excellent on the class level. For the second subscale, Cronbach’s alpha was low on level 1 and excellent on level 2. Weak relations between self-efficacy values and MVPA were found for level 1, strong associations were found for level 2.Conclusions The validation speaks in favour of a two-dimensional scale measuring not only actual self-efficacy but also support from family and friends. Furthermore, the results argue for the relevance of the multi-level approach which is able to differentiate between self-efficacy on the individual level and collective efficacy on the class level.

Fair value's effects on closed-end funds' discounts and premia: is level 3 the sole perpetrator?

2020 ◽  
Vol 46 (8) ◽  
pp. 1001-1022 ◽  
Author(s):  
Steve Fortin ◽  
Ahmad Hammami ◽  
Michel Magnan
Keyword(s):  
Relevant Information ◽  
Fair Value ◽  
Content Type ◽  
Level 3 ◽  
Closed End Funds ◽  
Level 1 ◽  
Value Hierarchy ◽  
Valuation Uncertainty ◽  
The Impact ◽  
Level 2

PurposeThis study examines the long-term link between fair valuation uncertainty and discounts/premia in closed-end funds. This study argues that, in exploring the close-end funds puzzle, prior research generally omits to consider the uncertainty surrounding the measurement of funds' financial disclosure, as reflected in the fair value hierarchy, when investment specialty differs across funds.Design/methodology/approachRegressions were employed to explore how the fair value hierarchy affects closed-end funds' discounts/premia when investment specialty differs. The authors also examine the effects pre- and post-2012 to explore if that relationship changes due to the additional disclosure requirements enacted at the end of 2011.FindingsThe authors find that the three levels of the fair value hierarchy have effects that vary according to a fund's specialty. For equity specialized funds, Level 3 significantly increases discounts and decreases premia, suggesting the impact of valuation uncertainty that underlies Level 3 estimates; this relationship disappears (decreases in severity) for premia (discount) experiencing funds post-2012. In contrast, Level 1 and Level 2 do not have any significant effect on discounts or premia except that post-2012, Level 2 begins to display discount decreasing effects. For bond specialized funds, no significant association was noted between premia and any of the fair value levels except that post-2012, Level 3 begins to display premium increasing effects. However, results are different for discounts. The authors note that Level 1 valuations significantly increase discounts, but only post-2012; Level 2 valuations significantly decrease discounts (pre- and post-2012), consistent with such estimates incorporating unique and relevant information; and Level 3 valuations do not have a significant effect on discounts.Originality/valueThe results of this study revisit prior evidence and indicate that results about the effects of fair value measurement and the closed-end funds' puzzle are sensitive to the period length being considered and the investment specialty of the fund. The authors also note that additional disclosure regarding Level 3 valuation inputs decreases market concern for valuation uncertainty and increases the liquidity benefits of investing in Level 3 carrying funds.

scholarly journals Prevalence of Trypanosoma evansi in horses (Equus caballus) and donkeys (Equus asinus) in El-Bayadh district, southwestern Algeria

2019 ◽  
Vol 70 (3) ◽  
pp. 1631 ◽  
Author(s):  
K. BENFODIL ◽  
S. ANSEL ◽  
A. MOHAMED-CHERIF ◽  
K. AIT-OUDHIA
Keyword(s):  
Domestic Animals ◽  
Trypanosoma Evansi ◽  
Seroprevalence Rate ◽  
Endemic Region ◽  
Equus Asinus ◽  
Level 3 ◽  
Level 1 ◽  
The Individual ◽  
Associate Risk ◽  
Level 2

Trypanosoma evansi is a parasite that causes surra in a variety of wild and domestic animals and is mainly transmitted by biting flies in Africa, Asia and Latin-America. Horses infected by Trypanosoma evansi present a chronic weight loss, icterus, oedema, anemia, abortions and neurological troubles. Due to this parasite, cases of human trypanosomiosis have been reported in different countries by contacting with infected animals. In this study, 206 healthy equines (177 horses and 29 donkeys) from El-Bayadh district, located in southwest Algeria, were tested for the presence of parasites in blood using Giemsa-stained blood films and for the presence of antibodies against T. evansi using CATT /T. evansi. While none of the equines showed detectable parasites in the blood, the individual seroprevalence of T. evansi was found to be 46.6% (CI 95%, 40.7-54.4%). Out of 98 positives samples, 56.1% (55/98) were shown at level 1 (+), 27.5% (27/98) at level 2 (++) and 16.3% (16/98) at level 3 (+++). The results show that out of 177 tested horses, 80 were seropositive to T. evansi, 45.2% (CI 95%, 37.8-52.5%) and out of 29 tested donkeys, 18 were seropositive to T. evansi, 62.1% (CI 95%, 44.4-79.7%). A questionnaire for the owners, targeted to associate risk factors for surra in horses, showed that environmental factors that are favorable for Tabanids, such as water and vegetation, but also promiscuity with dromedaries were positively associated with the seroprevalence rate in the horses. El-Bayadh district is a highly endemic region for surra in Algeria.

Managerial ability and fair value accounting: evidence from nonfinancial firms

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wray Bradley ◽  
Li Sun
Keyword(s):  
Design Methodology ◽  
Fair Value ◽  
Managerial Ability ◽  
Fair Value Accounting ◽  
Content Type ◽  
Level 3 ◽  
Level 1 ◽  
The Impact ◽  
Nonfinancial Firms ◽  
Level 2

Purpose The purpose of this study is to examine the relation between managerial ability and fair value inputs (measured as fair value intensity) for nonfinancial firms. Design/methodology/approach This study uses regression analysis to investigate the impact of managerial ability on the level of fair value inputs. Findings This study finds significant and positive relations between managerial ability and use of Level 1 and Level 2 fair value inputs. On the other hand, this study finds an insignificant relation between managerial ability and Level 3 inputs. Originality/value The findings contribute to two research streams. To the best of the author’s knowledge, this is perhaps the first study that directly examines the link between managerial ability and fair value inputs.

scholarly journals A Two-Level Flow-Based Anomalous Activity Detection System for IoT Networks

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 530 ◽  
Author(s):  
Imtiaz Ullah ◽  
Qusay H. Mahmoud
Keyword(s):  
Network Flow ◽  
Detection System ◽  
Activity Detection ◽  
Malicious Activity ◽  
Proposed Model ◽  
Tree Classifier ◽  
Level 1 ◽  
Iot Devices ◽  
The Impact ◽  
Level 2

The significant increase of the Internet of Things (IoT) devices in smart homes and other smart infrastructure, and the recent attacks on these IoT devices, are motivating factors to secure and protect IoT networks. The primary security challenge to develop a methodology to identify a malicious activity correctly and mitigate the impact of such activity promptly. In this paper, we propose a two-level anomalous activity detection model for intrusion detection system in IoT networks. The level-1 model categorizes the network flow as normal flow or abnormal flow, while the level-2 model classifies the category or subcategory of detected malicious activity. When the network flow classified as an anomaly by the level-1 model, then the level-1 model forwards the stream to the level-2 model for further investigation to find the category or subcategory of the detected anomaly. Our proposed model constructed on flow-based features of the IoT network. Flow-based detection methodologies only inspect packet headers to classify the network traffic. Flow-based features extracted from the IoT Botnet dataset and various machine learning algorithms were investigated and tested via different cross-fold validation tests to select the best algorithm. The decision tree classifier yielded the highest predictive results for level-1, and the random forest classifier produced the highest predictive results for level-2. Our proposed model Accuracy, Precision, Recall, and F score for level-1 were measured as 99.99% and 99.90% for level-2. A two-level anomalous activity detection system for IoT networks we proposed will provide a robust framework for the development of malicious activity detection system for IoT networks. It would be of interest to researchers in academia and industry.

scholarly journals Comparison between the assimilation of IASI Level 2 retrievals and Level 1 radiances for ozone reanalyses

2019 ◽  
Author(s):  
Emanuele Emili ◽  
Brice Barret ◽  
Eric Le Flochmoën ◽  
Daniel Cariolle
Keyword(s):  
Transport Model ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Atmospheric Sounding ◽  
Level 1 ◽  
The Tropics ◽  
L1 And L2 ◽  
The Impact ◽  
Level 2

Abstract. The prior information used for Level 2 (L2) retrievals in the thermal infrared can influence the quality of the retrievals themselves and, therefore, their further assimilation in atmospheric composition models. In this study we evaluate the differences between assimilating L2 ozone profiles and Level 1 (L1) radiances from the Infrared Atmospheric Sounding Interferometer (IASI). We minimized potential differences between the two approaches by employing the same radiative transfer code (RTTOV) and a very similar setup for both the L2 retrievals (1D-Var) and the L1 assimilation (3D-Var). We computed hourly 3D-Var reanalyses assimilating respectively L1 and L2 data in the chemical transport model MOCAGE and compared the resulting O3 fields among each other and against ozonesondes. We also evaluated the joint assimilation of limb measurements from the Microwave Limb Sounder (MLS) on top of IASI to assess the impact of stratospheric O3 on tropospheric reanalyses. Results indicate that significant differences can arise between L2 and L1 assimilation, especially in regions where the L2 prior is biased (at the tropics and in the southern hemisphere in this study). L1 and L2 assimilation give instead very similar results in the northern hemisphere, especially when MLS measurements are used to constrain the stratospheric O3 column. We conclude this study by listing remaining issues that are common to both the L1 and L2 approaches and that deserve further research.

scholarly journals Scientific Production of Researchers Recipiente of CNPq Productivity Grants in the Field of Production Engineering in the 2013-2016 period

2021 ◽  
Vol 10 (2) ◽  
pp. e15010212378
Author(s):  
Priscila Rubbo ◽  
Bruno Pedroso ◽  
Guilherme Moreira Caetano Pinto ◽  
Luiz Alberto Pilatti ◽  
Claudia Tania Picinin
Keyword(s):  
Quantitative Data ◽  
Technological Development ◽  
Scientific Production ◽  
Descriptive Statistics ◽  
Production Engineering ◽  
Contrast Level ◽  
Normality Test ◽  
Level 1 ◽  
The Individual ◽  
Level 2

This work has the purpose of mapping the scientific production of researchers recipient of CNPq productivity grants in research (PQ) and productivity grants in technological development and innovative extension (DT), in the Production Engineering field, in the four-year period from 2013 to 2016. The information was extracted from the Lattes Platform, on which we obtained quantitative data about the individual scientific production of 190 researchers, through the software scripLattes v8.10. The data analysis was conducted through descriptive statistics, the Kolgomorov-Smirnov data normality test, the Kruskal-Wallis test, and the Mann-Whitney test. The results show that 76% of the researchers compose the PQ grant category. Within the four-year period, among PQ researchers, 1B and 1A researchers had the best average of total published articles, with 19.42 and 15.75 articles per researcher, respectively. Among DT researchers, 1D and level 2 researchers had, in average, 21.5 and 12.57 published articles, respectively. PQ researchers maintain their production of scientific articles homogeneous at all Qualis levels. On the other hand, DT researchers present greater heterogeneity in their publications. It is possible to conclude that level 1 researchers do not focus on journals that present low Qualis ratings for the publication of their research. In contrast, level 2 researchers are less experienced and expect to publish in higher-level journals, but when their works are rejected, they start “betting” on journals of lesser quality.

Illiquid Assets and the Opacity Discount in Banks’ Valuation

2021 ◽  
Author(s):  
Giulio Anselmi
Keyword(s):  
Negative Relationship ◽  
Relative Weight ◽  
Fair Value ◽  
Book Value ◽  
Valuation Technique ◽  
Level 3 ◽  
Level 1 ◽  
The Impact ◽  
Level 2 ◽  
Illiquid Assets

The paper investigates the impact of fair value accounting for illiquid assets (so-called ‘Level 2’ and ‘Level 3’ assets by accounting rules) on banks’ valuation and focuses on the change in relative weight of Level 3 (the most opaque and illiquid assets) with respect to Level 2 assets. The boundary between Level 3 and Level 2 assets is blurred and less clear than the one between Level 1 and Level 2 assets. Such unclear borderline entails corporate governance issues and provides room for opportunistic behavior by managers to opt for less transparent instruments. The paper proposes the change in Level 3-to-Level 2 assets ratio as a new measure to capture deviations in the opacity of bank assets and suggests a negative relationship between this ratio and bank’s price-to-book value. The rationale behind this relationship is that market participants interpret growth in Level 3-to-Level 2 assets ratio as an increase in bank’s opacity, since Level 3 assets might be as illiquid as Level 2 assets with the benefit of a less transparent model-based valuation technique. Based on a sample of 33 European banks from 2009 to 2018, I find that an increase of 100[Formula: see text]bps in Level 3-to-Level 2 assets ratio is linked to a decrease of about 74[Formula: see text]bps in the price-to-book value. Results are robust for different measures of firm relative valuation and using a different measure of illiquidity in fair value assets holdings (Level 2-to-Level 1 assets ratio).

Value Relevance of FAS No. 157 Fair Value Hierarchy Information and the Impact of Corporate Governance Mechanisms

2010 ◽  
Vol 85 (4) ◽  
pp. 1375-1410 ◽  
Author(s):  
Chang Joon Song ◽  
Wayne B. Thomas ◽  
Han Yi
Keyword(s):  
Corporate Governance ◽  
Value Relevance ◽  
Fair Value ◽  
Governance Mechanisms ◽  
Corporate Governance Mechanisms ◽  
Level 3 ◽  
Level 1 ◽  
The Impact ◽  
Fair Value Measurements ◽  
Level 2

ABSTRACT: Statement of Financial Accounting Standards No. 157 (FAS No. 157), Fair Value Measurements, prioritizes the source of information used in fair value measurements into three levels: (1) Level 1 (observable inputs from quoted prices in active markets), (2) Level 2 (indirectly observable inputs from quoted prices of comparable items in active markets, identical items in inactive markets, or other market-related information), and (3) Level 3 (unobservable, firm-generated inputs). Using quarterly reports of banking firms in 2008, we find that the value relevance of Level 1 and Level 2 fair values is greater than the value relevance of Level 3 fair values. In addition, we find evidence that the value relevance of fair values (especially Level 3 fair values) is greater for firms with strong corporate governance. Overall, our results support the relevance of fair value measurements under FAS No. 157, but weaker corporate governance mechanisms may reduce the relevance of these measures.

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