263 research outputs found

    A study on embryonic development of Yellow Fin Seabream (Acanthopagrus latus)

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    Embryonic and larval development stages of yellow fin seabream (Acanthopagrus latus) were studied in two average temperatures (21 and 24C) in Marine Fish Research Center in Emam Khomeini Port. Egg diameter in initiation of fertilization was 739.35 plus or minus 0.0081k and during final hatching it was 792.36 plus or minus 0.0095k. The average egg diameter from fertilization until final hatching was 763.49 plus or minus 0.00l6k. The average egg diameter was 751.81 plus or minus 0.0064k in murola stage, 767.55 plus or minus 0.0074k in nurula stage, 779.97 plus or minus 0.0084k in appearance of heart stage and 780.84 plus or minus 0.0086k in the increasing of pigmentation stage. Duration of egg incubation and embryo development of yellow fin seabream (Acanthopagrus latus) was 31 hours and 15 minutes at 20clC and 26 hours and 15 minutes at 23 plus or minus 1C. In this study, 20 stages of embryo development of yellow fin seabream were identified through incubation period from fertilization to final hatching. It seems that water temperature can be an effective environmental factor in the fish embryo development, so that hatching at 20clC occurred in 5 hours later than when at 23clC. Temperature change had no effect on the number of larvae and characteristics of embryo development. The information gathered through this study is useful when planning for artificial reproduction of this commercial species and can improve the propagation process

    How to Make an Outlier? Studying the Effect of Presentational Features on the Outlierness of Items in Product Search Results

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    In two-sided marketplaces, items compete for attention from users since attention translates to revenue for suppliers. Item exposure is an indication of the amount of attention that items receive from users in a ranking. It can be influenced by factors like position bias. Recent work suggests that another phenomenon related to inter-item dependencies may also affect item exposure, viz. outlier items in the ranking. Hence, a deeper understanding of outlier items is crucial to determining an item's exposure distribution. In this work, we study the impact of different presentational e-commerce features on users' perception of outlierness of an item in a search result page. Informed by visual search literature, we design a set of crowdsourcing tasks where we compare the observability of three main features, viz. price, star rating, and discount tag. We find that various factors affect item outlierness, namely, visual complexity (e.g., shape, color), discriminative item features, and value range. In particular, we observe that a distinctive visual feature such as a colored discount tag can attract users' attention much easier than a high price difference, simply because of visual characteristics that are easier to spot. Moreover, we see that the magnitude of deviations in all features affects the task complexity, such that when the similarity between outlier and non-outlier items increases, the task becomes more difficult.</p

    Modeling and simulation of pedestrian movement planning around corners

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    Owing to the complexity of behavioral dynamics and mechanisms associated with turning maneuvers, capturing pedestrian movements around corners in a mathematical model is a challenging task. In this study, minimum jerk and one-thirds power law concepts, which have been initially applied in neurosciences and brain research domains, were utilized in combination to model pedestrian movement planning around bends. Simulation outputs explained that the proposed model could realistically represent the behavioral characteristics of pedestrians walking through bends. Comparison of modeled trajectories with empirical data demonstrated that the accuracy of the model could further be improved by using appropriate parameters in the one-thirds power law equation. Sensitivity analysis explained that, although the paths were not sensitive to the boundary conditions, speed and acceleration profiles could be remarkably varied depending on boundary conditions. Further, the applicability of the proposed model to estimate trajectories of pedestrians negotiating bends under different entry, intermediate, and exit conditions was also identified. The proposed model can be applied in microscopic simulation platforms, virtual reality, and driving simulator applications to provide realistic and accurate maneuvers around corners. - 2019 by the authors.Acknowledgments: The publication of this article was funded by the Qatar National Library

    On the Impact of Outlier Bias on User Clicks

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    User interaction data is an important source of supervision in counterfactual learning to rank (CLTR). Such data suffers from presentation bias. Much work in unbiased learning to rank (ULTR) focuses on position bias, i.e., items at higher ranks are more likely to be examined and clicked. Inter-item dependencies also influence examination probabilities, with outlier items in a ranking as an important example. Outliers are defined as items that observably deviate from the rest and therefore stand out in the ranking. In this paper, we identify and introduce the bias brought about by outlier items: users tend to click more on outlier items and their close neighbors. To this end, we first conduct a controlled experiment to study the effect of outliers on user clicks. Next, to examine whether the findings from our controlled experiment generalize to naturalistic situations, we explore real-world click logs from an e-commerce platform. We show that, in both scenarios, users tend to click significantly more on outlier items than on non-outlier items in the same rankings. We show that this tendency holds for all positions, i.e., for any specific position, an item receives more interactions when presented as an outlier as opposed to a non-outlier item. We conclude from our analysis that the effect of outliers on clicks is a type of bias that should be addressed in ULTR. We therefore propose an outlier-aware click model that accounts for both outlier and position bias, called outlier-aware position-based model (OPBM). We estimate click propensities based on OPBM; through extensive experiments performed on both real-world e-commerce data and semi-synthetic data, we verify the effectiveness of our outlier-aware click model. Our results show the superiority of OPBM against baselines in terms of ranking performance and true relevance estimation.</p

    Surface-functionalization of PDMS for potential micro-bioreactor and embryonic stem cell culture applications

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    This study presents a novel and inexpensive method to prepare a disposable micro-bioreactor for stem cell expansion. The micro-bioreactor was fabricated in the form of a fixed bed bioreactor with a microchannel reactor bed. The micro-bioreactor was constructed from polydimethylsiloxane (PDMS), and the microchannel was functionalized to enable cell adhesion and resistance to bovine serum albumin protein adsorption. The PDMS reactor bed surface was activated by oxygen plasma, then aminized with trimethoxysilylpropyl(polyethyleneimine), followed by grafting with carboxylmethyl cellulose (CMC) and gelatin in sequence. The functionalized PDMS surface demonstrated improved hydrophilicity and antifouling properties. The grafting of gelatin promoted cell adhesion. The functionalized surface was found to be biocompatible with MDA-MB-231 and Oct4b2 cells and was demonstrated to facilitate cell proliferation. The expanded Oct4b2 cells retained their proliferation potential, undifferentiated phenotype and pluripotency

    Relationship between urbanization and cancer incidence in Iran using quantile regression

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    Quantile regression is an efficient method for predicting and estimating the relationship between explanatory variables and percentile points of the response distribution, particularly for extreme percentiles of the distribution. To study the relationship between urbanization and cancer morbidity, we here applied quantile regression. This cross-sectional study was conducted for 9 cancers in 345 cities in 2007 in Iran. Data were obtained from the Ministry of Health and Medical Education and the relationship between urbanization and cancer morbidity was investigated using quantile regression and least square regression. Fitting models were compared using AIC criteria. R (3.0.1) software and the Quantreg package were used for statistical analysis. With the quantile regression model all percentiles for breast, colorectal, prostate, lung and pancreas cancers demonstrated increasing incidence rate with urbanization. The maximum increase for breast cancer was in the 90th percentile (β=0.13, p-value < 0.001), for colorectal cancer was in the 75th percentile (β=0.048, p-value < 0.001), for prostate cancer the 95th percentile (β=0.55, p-value < 0.001), for lung cancer was in 95th percentile (β=0.52, p-value=0.006), for pancreas cancer was in 10th percentile (β=0.011, p-value < 0.001). For gastric, esophageal and skin cancers, with increasing urbanization, the incidence rate was decreased. The maximum decrease for gastric cancer was in the 90th percentile(β=0.003, p-value < 0.001), for esophageal cancer the 95th (β=0.04, p-value=0.4) and for skin cancer also the 95th (β=0.145, p-value=0.071). The AIC showed that for upper percentiles, the fitting of quantile regression was better than least square regression. According to the results of this study, the significant impact of urbanization on cancer morbidity requirs more effort and planning by policymakers and administrators in order to reduce risk factors such as pollution in urban areas and ensure proper nutrition recommendations are made. © 2016, Asian Pacific Journal of Cancer Prevention

    Estimating the completeness of gastric cancer registration in Ardabil/Iran by a capture-recapture method using population-based cancer registry data

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    Background: Knowledge of cancer incidences is essential for cancer prevention and control programs. Capture-recapture methods have been recommended for reducing bias and increasing the accuracy of cancer incidence estimations. This study aimed to estimate the completeness of gastric cancer registration by the capture-recapture method based on Ardabil population-based cancer registry data. Materials and Methods: All new cases of gastric cancer reported by three sources, pathology reports, death certificates and medical records that reported to Ardabil population-based cancer registry in 2006 and 2008 were enrolled in the study. The duplicate cases based on the similarity of first name, surname and fathers names were identified between sources. The estimated number of gastric cancers was calculated by the log-linear method using Stata 12 software. Results: A total of 857 new cases of gastric cancer were reported from three sources. After removing duplicates, the reported incidence rates for the years 2006 and 2008 were 35.3 and 32.5 per 100,000 population, respectively. The estimated completeness calculated by log-linear method for these years was 36.7 and 36.0, respectively. Conclusions: These results indicate that none of the sources of pathology reports, death certificates and medical records individually or collectively fully cover the incident cases of gastric cancer. We can obtain more accurate estimates of incidence rates using the capture-recapture method

    Estimating the completeness of lung cancer registry in Ardabil, Iran with a three-source capture-recapture method

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    Cancer registration is an important component of a comprehensive cancer control program, providing timely data and information for research and administrative use. Capture-recapture methods have been used as tools to investigate completeness of cancer registry data. This study aimed to estimate the completeness of lung cancer cases registered in Ardabil Population Based Cancer Registry (APBCR) with a three-source capture-recapture method. Data for all new cases of lung cancer reported by three sources (pathology reports, death certificates, and medical records) to APBCR for 2006 and 2008 were obtained. Duplicate cases shared among the three sources were identified based on similarity of first name, last name and father's names. A log-linear model was used to estimate number of missed cases and to control for dependency among sources. A total of 218 new cases of lung cancer was reported by three sources after removing duplicates. The estimated completeness calculated by log-linear method was 26.4 for 2006 and 27.1 for 2008. The completeness differed according to gender. In men, the completeness was 26.0 for 2006 and 28.1 for 2008. In women, the completeness was 36.5 for 2006 and 46.9 for 2008. In conclusion, none of the three sources can be considered as a reliable source for accurate cancer incidence estimation. © 2016, Asian Pacific Journal of Cancer Prevention
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