Subsequent Time Periods Research Articles

Curved Path Following for Unmanned Surface Vehicles With Heading Amendment

This article presents two interrelated problems-along tracking and cross tracking-in guidance design for curved path following for unmanned surface vehicles. Since these two types of directional tracking are interactively constrained in most research work, an iteration mechanism is first put forward to optimize the path parameter in each closed loop such that along tracking will not affect cross tracking in the subsequent time period. An extended line-of-sight (ELOS) guidance principle is then proposed by varying the look-ahead distance with the cross-track error such that sideslip in cross tracking can be promptly compensated through vehicle heading amendment. Both simulation and experimental results verify the effectiveness of the proposed methods, which perform better than the conventional line-of-sight (LOS) and integral LOS (ILOS) guidance laws.

Racial/ethnic, age and sex disparities in leukemia survival among adults in the United States during 1973-2014 period.

There has been marked improvement in leukemia survival, particularly among children in recent time. However, the long-term trends in survival among adult leukemia patients and the associated sex and racial survival disparities are not well understood. We, therefore, evaluated the secular trends in survival improvement of leukemia patients from 1973 through 2014, using Surveillance Epidemiology and End-Result Survey Program (SEER) data. ICD-O-3 morphology codes were used to group leukemia into four types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML). Survival analysis for each leukemia type stratified by race/ethnicity, age, sex was performed to generate relative survival probability estimates for the baseline time period of 1973 through 1979. Hazard ratios (HR) and respective 95% confidence intervals (CIs) for survival within subsequent 10-year time periods by race, age and sex were calculated using Cox proportional hazard models. Of the 83,255 leukemia patients for the current analysis, the 5-year survival of patients with ALL, AML, CLL, and CML during 1973–1979 were 42.0%, 6.5%, 66.5%, and 20.9%, respectively. Compared to the baseline, there were substantial improvements of leukemia-specific survival in 2010–2014 among African-American (81.0%) and Asian (80.0%) patients with CML and among 20–49 year of age with CLL (96.0%). African-American patients, those with AML and those older than 75 years of age had the lowest survival improvements. Asians experienced some of the largest survival improvements during the study period. Others, including African-American and the elderly, have not benefited as much from advances in leukemia treatment.

Three dimensional characterization of meteorological and hydrological droughts and their probabilistic links

Meteorological and hydrological droughts are inherently correlated, but with a time lag. A prolonged precipitation deficiency propagates to surface water bodies and may give rise to hydrological drought in the subsequent time period. Establishing links between these two drought types is of great significance for water resources planning and for developing drought resistant measures. This study proposes a copula-based method employing conditional probability distribution to depict the structure of dependence between the characteristics of meteorological and hydrological droughts. The time series of grid-based standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) were derived from the simulations of the variable infiltration capacity (VIC) model over the Yellow River basin (YRB) during 1961–2012. Then, using a three-dimensional (time-latitude-longitude) drought identification method, three drought characteristics, including duration, area and severity, were extracted for meteorological and hydrological droughts. For analyzing drought characteristics, return periods and connection between meteorological and hydrological droughts, a probabilistic framework using the copula function, was developed. Results showed that there was a general drying tendency both for meteorological and hydrological droughts with longer duration and larger spatial extent. According to the trivariate joint distribution of duration, area and severity, the most severe meteorological and hydrological droughts over the YRB occurred around 1998–2000, with return periods exceeding 50 years. In terms of establishing the dependence between characteristics of meteorological and hydrological droughts, traditional statistical models like the linear, exponential, and power functions presented significant deviations, especially for severe or extreme drought conditions. In contrast, the copula based conditional distribution method provided a satisfactorily probabilistic prediction of hydrological drought characteristics given the information of meteorological drought characteristics. The stability test suggested compared to the length of data sample, the incorporation of typical major drought events with long persistence and wide spatial extent is more important for reliable drought prediction.

Sustained Increases in the Quality of Imaging Histories Provided by Ordering Providers Resulting From Multidisciplinary Collaboration and Systems Design.

OBJECTIVE. The purpose of this quality improvement project was to create sustained improvement in the frequency of more complete imaging histories provided with imaging examinations submitted directly by ordering providers. A secondary purpose was increasing the number of characters submitted by ordering providers with imaging examinations. MATERIALS AND METHODS. A multidisciplinary team defined the components of a complete imaging history, a process that underwent several improvement cycles. Audits were regularly performed using consensus, and the project team regularly evaluated the completeness of the imaging histories. The final components of the definition of a complete imaging history included responses regarding what happened, when it happened, where the patient was experiencing pain, and the ordering provider's concern. Prompts were inserted into the electronic physician order entry process, and performance was monitored for an additional 18 months. RESULTS. A total of 10,236 orders were placed by providers in the study clinic from March 13, 2017, to December 16, 2018. Of the orders audited in the baseline period, 16.0% (64/397) of orders audited in the baseline period contained all four history components, which increased to 52.0% (2200/4234; absolute increase of 36.0%, relative increase of 225.0%; p < 0.0001) in the subsequent time periods, and improvement was sustained. The mean number of characters providers entered in the imaging histories they submitted increased from 45.4 characters per order during the baseline period to 75.4 (66.1% increase, p < 0.0001) after the intervention. CONCLUSION. By collaborating with a multidisciplinary team, we created a standardized definition of an imaging history, engineered our systems to include supportive prompts in the order entry interface, and sustainably improved the quality of imaging histories provided.

Do mutual funds have consistency in their performance?

Using a comprehensive data set of 714 Chinese mutual funds from 2004 to 2015, the study investigates these funds’ performance persistence by using the Capital Asset Pricing model, the Fama-French three-factor model and the Carhart Four-factor model. For persistence analysis, we categorize mutual funds into eight octiles based on their one year lagged performance and then observe their performance for the subsequent 12 months. We also apply Cross-Product Ratio technique to assess the performance persistence in these Chinese funds. The study finds no significant evidence of persistence in the performance of the mutual funds. Winner (loser) funds do not continue to be winner (loser) funds in the subsequent time period. These findings suggest that future performance of funds cannot be predicted based on their past performance.

Impact of a single treatment of injectable doramectin on weight gain post weaning in beef heifers and steers in central Queensland, Australia.

To demonstrate the impact of a single drench with a label dose of injectable doramectin subsequent to weaning on the growth and performance of heifers and steers in central Queensland beef herds. Three studies were undertaken on recently-weaned Bos indicus-cross beef calves with ≥ 75% B. indicus content on two farms in central Queensland, just north of the Tropic of Capricorn. Farm 1 was located 50 km north and Farm 2 75 km north-west of Rockhampton. In each study, half of a group of recently-weaned beef calves were treated by random allocation with 0.2 mg/kg of injectable doramectin, and the remainder acting as untreated controls. Study 1 (Farm 1) enrolled 250 heifers, while studies 2 and 3 (Farm 2) both enrolled 200 steers and 200 heifers. The farms involved did not historically use macrocyclic lactone-based drenches on their cattle. There were varying periods of follow-up, with treated and control cattle pastured as one group throughout the study period. Worm burdens were monitored using standard faecal egg counts and larval differentiation procedures. In all studies, the worm genera present were a mix of Cooperia spp., Haemonchus spp. and Oesophagostomum spp. In study 1, conducted on Farm 1 beginning 9 July 2012, doramectin-treated cattle gained an average of 0.27 kg/day while control cattle gained 0.19 kg/day over a monitoring period of 121 days (P < 0.0001). In study 2, conducted on Farm 2 beginning 28 July 2015, doramectin-treated cattle gained an average of 0.15 kg/day versus 0.145 kg/day in the control group (P = 0.44) over a 231-day study period. In study 3, conducted on Farm 2 beginning 4 August 2016, doramectin-treated steers and heifers gained an average of 0.431 and 0.402 kg/day versus 0.342 and 0.311 kg/day in the control group, respectively, over the first 91 days of the study (P < 0.0001 in both cases). The differences in average daily gain (ADG) in subsequent time periods were not statistically significant for steers or heifers. However, overall differences in ADG from day 0 remained statistically significant out to day 258, when the study ended for the heifers. By day 594, when the study ended for the steers, the difference in ADG was no longer significant. Treatment with injectable doramectin soon after weaning resulted in improved weight gain in the 3 months after weaning in two of the three studies.

Optical Coherence Tomography Segmentation Errors of the Retinal Nerve Fiber Layer Persist Over Time.

To identify whether optical coherence tomography (OCT) segmentation errors in RNFL thickness measurements persist longitudinally. This was a cohort study. We used spectral domain OCT (Spectralis) to measure RNFL thickness in a 6-degree peripapillary circle, and exported the native "automated segmentation only" results. In addition, we exported RNFL thickness results after "manual refinement" to correct errors in the automated segmentation, and used the differences in these measurements as "error" in segmentation. We used Bland-Altman plots and linear regression to determine the magnitude, location, and repeatability of RNFL thickness error in all twelve 30-degree sectors and compared the error at baseline to follow-up time points at 6 months, 2 years, 3 years, and 4 years. We included 406 eyes from 213 participants. The 95% confidence interval for errors at baseline was -6.5 to +13.2 μm. The correlation between the baseline error and the errors in the follow-up time periods were high (r>0.5, P<0.001 for all). Automated segmentation had a smaller SD of residuals from the longitudinal trend line when compared to manual refinement (1.56 vs. 1.80 μm, P<0.001), and a higher ability (P=0.009) to monitor progression using an analysis of a longitudinal signal-to-noise ratio. Errors in automated segmentation remain relatively stable, and baseline error is highly likely to persist in the same direction and magnitude in subsequent time periods. However, automated segmentation (without manual refinement) is more repeatable and may be more sensitive to glaucomatous progression. Future segmentation algorithms could exploit these findings to improve automated segmentation in the future.

Timing and Causes of Unplanned Readmissions After Percutaneous Coronary Intervention: Insights From the Nationwide Readmission Database

ObjectivesThe aim of this study was to describe the rates and causes of unplanned readmissions at different time periods following percutaneous coronary intervention (PCI). BackgroundThe rates and causes of readmission at different time periods after PCI remain incompletely elucidated. MethodsPatients undergoing PCI between 2010 and 2014 in the U.S. Nationwide Readmission Database were evaluated for the rates, causes, predictors, and costs of unplanned readmission between 0 and 7 days, 8 and 30 days, 31 and 90 days, and 91 and 180 days after index discharge. ResultsThis analysis included 2,412,000 patients; 2.5% were readmitted between 0 and 7 days, 7.6% between 8 and 30 days, 8.9% between 31 and 90 days, and 8.0% between 91 and 180 days (cumulative rates 2.5%, 9.9%, 18.0%, and 24.8%, respectively). The majority of readmissions during each time period were due to noncardiac causes (53.1% to 59.6%). Nonspecific chest pain was the most common identifiable noncardiac cause for readmission during each time period (14.2% to 22.7% of noncardiac readmissions). Coronary artery disease including angina was the most common cardiac cause for readmission during each time period (37.4% to 39.3% of cardiac readmissions). The second most common cardiac cause for readmission was acute myocardial infarction between 0 and 7 days (27.6% of cardiac readmissions) and heart failure during all subsequent time periods (22.2% to 23.7% of cardiac readmissions). ConclusionsApproximately 25% of patients following PCI have unplanned readmissions within 6 months. Causes of readmission depend on the timing at which they are assessed, with noncardiovascular causes becoming more important at longer time points.

Bias correcting climate model multi-member ensembles to assess climate change impacts on hydrology

Bias correction is usually applied to climate model outputs before they are used as inputs to environmental models for impact studies. Every climate model is post-processed independently of others to account for biases originating from model structure and internal variability. To better understand the role of internal variability, multi-member ensembles (multiple runs of a single climate model, with identical forcing but different initial conditions) have now become common in the modeling community. Bias correcting such ensembles requires specific considerations. Correcting all members of such an ensemble independently would force all of them to the target distribution, thus removing the signature of natural variability over the calibration period. How this undesirable effect would propagate onto subsequent time periods is unknown. This study proposes three bias correction variants of a multi-member ensemble and compares their performances against an independent correction of each individual member of the ensemble. The comparison is based on precipitation and temperature, as well as on resulting streamflows simulated by a hydrological model. Two multi-member ensembles (5-member CanESM2 and 10-member CSIRO-MK3.6) were used for a subtropical monsoon watershed in China. The results show that all bias correction methods reduce precipitation and temperature biases for all ensemble members. As expected, independent correction reduces the spread of each ensemble over the calibration period. This is, however, followed by an overestimation of the spread over the subsequent validation period. Pooling all members to calculate common bias correction factors produces the best results over the calibration period; however, the difference among three bias correction variants becomes less clear over the validation period due to internal variability, and even less so when considering streamflows, as the impact model adds its own uncertainty.

A Generic First-Order Radiative Transfer Modelling Approach for the Inversion of Soil and Vegetation Parameters from Scatterometer Observations

We present the application of a generic, semi-empirical first-order radiative transfer modelling approach for the retrieval of soil- and vegetation related parameters from coarse-resolution space-borne scatterometer measurements ( σ 0 ). It is shown that both angular- and temporal variabilities of ASCAT σ 0 measurements can be sufficiently represented by modelling the scattering characteristics of the soil-surface and the covering vegetation-layer via linear combinations of idealized distribution-functions. The temporal variations are modelled using only two dynamic variables, the vegetation optical depth ( τ ) and the nadir hemispherical reflectance (N) of the chosen soil-bidirectional reflectance distribution function ( B R D F ). The remaining spatial variabilities of the soil- and vegetation composition are accounted for via temporally constant parameters. The model was applied to series of 158 selected test-sites within France. Parameter estimates are obtained by using ASCAT σ 0 measurements together with auxiliary Leaf Area Index ( L A I ) and soil-moisture ( S M ) datasets provided by the Interactions between Soil, Biosphere, and Atmosphere (ISBA) land-surface model within the SURFEX modelling platform for a time-period from 2007–2009. The resulting parametrization was then used used to perform S M and τ retrievals both with and without the incorporation of auxiliary L A I and S M datasets for a subsequent time-period from 2010 to 2012.

Net reductions or spatiotemporal displacement of intentional wildfires in response to arrests? Evidence from Spain

Research to date has not examined how the impacts of arrests manifest across space and time in environmental crimes. We evaluate whether arrests reduce or merely spatiotemporally displace intentional illegal outdoor firesetting. Using municipality-level daily wildfire count data from Galicia, Spain, from 1999 to 2014, we develop daily spatiotemporal ignition count models of agricultural, non-agricultural and total intentional illegal wildfires as functions of spatiotemporally lagged arrests, the election cycle, seasonal and day indicators, meteorological factors and socioeconomic variables. We find evidence that arrests reduce future intentional illegal fires across space in subsequent time periods.

The research on work engagement: theoretical aspects and the results of researches in the company operating in the IT sector

The aim of this article is to exemplify the results of researches on work engagement in the company operating in the IT sector. The research methodology includes the studies of scientific literature and the quantitative method (survey questionnaire). The sample in the study comprises 509 employees of a company operating in the IT sector. Work engagement was measured with of the original 17-item Utrecht Work Engagement Scale (UWES). Using in the research a standardized tool gives the opportunity to compare different results obtained in subsequent periods of time in the company, as well as, it can be the point of reference in the assessment of work engagement in other companies of the IT and other sectors. The results of the research show a relatively high level of work engagement in the composite aspect and its individual dimensions and subdimensions in the company operating in the IT sector. The scientific literature studies provide the managers with information on how various issues are related to the level of work engagement and on the usefulness of periodic researches in the company. However, the results of the empiric research help the managers to diagnose of the work engagement and to take more conscious decisions how to improve or maintain it on the same level. The research findings give the overview on the topic of work engagement level in a big IT company.

Impact of Market Risk on Credit Risk of Subsequent Period in Manufacturing Sector of Pakistan

Firm's business activities are focused on profit making. The cultural, technological, organizational, financial and operational challenges followed by different risks like market or credit risks make it difficult for firms to focus on their sole aim of earning profit. Previous studies have highlighted that market risk and credit risks have a significant influence on firm's performance. However, prediction of credit risk from market risk has not been explored in Pakistan which this paper attempts by investigating the impact of market risk on credit risk of the following period. For this study, a panel data of 30 manufacturing firms was collected through random sampling technique from period 2005 to 2016. A regression model was estimated in Generalized Method of Momments and used a Hausman test to select fixed or random effects. Results of this study show that firms have 30% more current liabilities as compared to current assets and experience volatility in stock prices which increases the credit risks. However, research findings shows that firms have reasonable growth opportunities and profitability they can be used to reduce stock volatility and attain confidence of creditors in firms. The increase in leverage due to creditor's confidence in firm indicates a decrease in credit risk. Overall the study shows the significantly negative impact of market risk on credit risk of the subsequent time period which specifies market risk may foresee credit risk of the following period and gives a new understanding for investors and policymakers to curb risks in investment decisions.

METHODICAL FOUNDATIONS OF HARBOUR DUES CALCULATION DEVELOPMENT

METHODICAL FOUNDATIONS OF HARBOUR DUES CALCULATION DEVELOPMENT

Self-attribution, Overconfidence and Dynamic Market Volatility in Indian Stock Market

The article provides an empirical evaluation of self-attribution, overconfidence bias and dynamic market volatility at Bombay Stock Exchange (BSE) across various market capitalizations. First, the investors’ reaction to market gain when they make right and wrong forecasts is studied to understand whether self-attribution bias causes investors’ overconfidence. It is found that when investors make right forecasts of future returns, they become overconfident and trade more in subsequent time periods. Next, the relation between excessive trading volume of overconfident investors and excessive prices volatility is studied. The trading volume is decomposed into a first variable related to overconfidence and a second variable unrelated to investors’ overconfidence. During pre-crisis period, the analysis of small stocks shows that conditional volatility is positively related to trading volume caused by overconfidence. During post-crisis period, the analysis shows that the under-confident investors became very pessimistic in small stocks and tend to overweight the future volatility. Whereas, the analysis of large stocks indicates that the overconfidence component of trading volume is positively correlated with the market volatility. Collectively, the empirical results provide strong statistical support to the presence of self-attribution and overconfidence bias explaining a large part of excessive and asymmetric volatility in Indian stock market.

Assessment of existing civil engineering structures

The upcoming CEN Technical Specification (TS) on assessment of existing structures is to be related to the probabilistic concepts and fundamental requirements of the EN Eurocodes. The document should concern all types structures made of concrete, steel and other materials, exposed to all kinds of actions. The final draft of the Technical specification was already submitted to the technical committee CEN TC250. It contains requirements, general framework of operational assessment, data updating, structural analysis (linear, nonlinear, dynamic), verifications (partial factors, probabilistic methods, risk assessment), past performance, interventions, annexes (flowchart, time-dependent reliability, assessment of heritage structures). The submitted contribution provides background information on the principles included in TS. Particular attention is paid to specifying appropriate target reliability levels and application of these values in engineering practice through adjustment of partial factors. It is shown that the operational assessment of existing concrete structures provides prediction of the remaining working life of a structure using a convenient reference period (commonly 50 years) taking into account durability aspects and mutual dependence of the failures in subsequent basic time periods (usually considered as one year).

Problems, perceptions and actions: An interdependent process for generating informal social control

Using two waves of survey data for residents in neighborhoods in Brisbane, this study explores the interdependent relationship between residents' perceptions of neighboring, cohesion, collective efficacy, neighborhood disorder, and the actions they take to address these problems. Our longitudinal results show that residents’ perceived severity of a problem helps explain engaging in activity to address the problem. People loitering appeared to be the most galvanizing problem for residents, but had particularly deleterious effects on perceptions of cohesion and collective efficacy. We also find that residents who perceive more neighboring in their local area engage in more public and parochial social control activity and residents who live in collectively efficacious neighborhoods are more likely to engage in parochial social control action. Furthermore, residents who themselves perceive more collective efficacy in the neighborhood engage in more parochial or public social control during the subsequent time period. Importantly, we find strong evidence that residents update their sense of collective efficacy. Perceiving more problems in the neighborhood, and perceiving that these problems are increasing, reduced perceptions of neighboring and collective efficacy over time.

Multi-period media planning for multi-products incorporating segment specific and mass media

Efficient budget allocation between different communication channels is one of the fundamental activities of any media planner. In this paper, we attempt to develop a multi-objective integer linear programming model to determine the optimal schedule of advertisements for a set of multiple products of a firm in a segmented market (influenced by both mass and segment-specific media) over a planning horizon. The objectives are to maximize the gross impressions of advertisements and simultaneously minimize the advertising expenditure. To incorporate continuous changes that occur in the market, the total planning horizon is divided into shorter time periods and decisions for each of the subsequent time periods are taken, bearing in mind the changes that have occurred in the preceding time periods. Based on the gap that exists in the extant literature, we also jointly consider, in our model, the notions of (a) carry-over effect of gross impressions, (b) spectrum effect of mass media on segments, and (c) cross-product effect. The model is solved through a goal programming approach to achieve the best trade-off between the conflicting objectives. Further, the model could be adapted to provide solutions in a wide variety of real-life situations. This is substantiated via a numerical analysis for a firm that advertises products in the Indian market through mass and segment-specific media.

A Cross Level Investigation on the Linkage Between Job Satisfaction and Voluntary Workplace Green Behavior

Building on the broaden-and-build theory of positive emotions and on social role theory, this research investigates the linkages among prior job satisfaction, voluntary workplace green behavior (VWGB), and subsequent job satisfaction as dependent on work group gender composition. With a multi-source, multi-time dataset, our random coefficient modeling demonstrated that job satisfaction positively predicts VWGB and that this pattern is more salient in work groups with more females. In addition, while VWGB does not yield job satisfaction in a subsequent time period, this positive linkage occurs in work groups with fewer females. This research offers theoretical implications for understanding the internal states and personal benefits of voluntary green performers as well as for the role of work group gender diversity on the linkages between prior job satisfaction and VWGB and between VWGB and subsequent job satisfaction. Our findings also illuminate the practical benefits of environmentally sustainable organizations.

The snow load in Europe and the climate change

It is often assumed that, as a consequence of global warming, a reduction of snow load on the ground should be expected. In reality, snow load is often depending on local orographic situations that can determine an increase of its height, even when the average snow height over the surrounding areas is reduced. Large snow loads on roofs during the winter season of 2005–2006 led to over 200 roof collapses in Central Europe. To proceed with the adaptation of the European standards for important buildings and infrastructures to the implications of climate change, the expected changes in the climatic loading shall be assessed in terms of the Eurocodes concept for characteristic values of variable climatic actions. The paper presents a procedure for derivation of snow load on ground from data on daily temperatures and precipitation. In addition, it allows to derive the characteristic snow loads from climate change projections and thus to evaluate the future trends in variation of snow loading. Analysis of these trends for the Italian territory is performed by comparing the results for several subsequent time periods of thirty years, with those obtained for the reference period 1951–1980. Results presented show a significant increase in the snow loading for the period 1981–2010 in many regions in north and east Italy in comparison with the reference period. It is suggested that a European project on snow load map shall be started, in order to help National Competent Authorities to redraft the national snow load maps for design with the Eurocodes.