The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Leonardo Campos - One of the best experts on this subject based on the ideXlab platform.
-
risk factors for the development of hospital acquired pediatric venous thromboembolism dealing with potentially causal and confounding risk factors using a directed acyclic graph dag analysis
PLOS ONE, 2020Co-Authors: Leonardo Campos, Mauricio Petroli, Elaine Sobral Da Costa, Leonardo R Brandao, Flavio Sztajnbok, Marcelo Gerardin Poirot LandAbstract:Introduction Hospital-acquired venous thromboembolism (HA-VTE) in children comprises multiple risk factors that should not be evaluated separately due to collinearity and multiple cause and effect relationships. This is one of the first case-control study of pediatric HA-VTE risk factors using a directed acyclic graph (DAG) analysis. Material and methods Retrospective, case-control study with 22 cases of objectively confirmed HA-VTE and 76 controls matched by age, sex, unit of admission, and period of hospitalization. Descriptive statistics were used to define distributions of continuous variables, frequencies, and proportions of categorical variables, comparing cases and controls. Due to many potential risk factors of HA-VTE, a directed acyclic graph (DAG) model was created to identify confounding, reduce bias, and increase precision on the analysis. The final model consisted of a DAG-informed conditional logistic regression. Results In the initial conventional univariable model, the following variables were selected as potential risk factors for HA-VTE: length of stay (LOS, days), immobility, ICU admission in the last 30 days, LOS in ICU, infection, central venous catheter (CVC), number of CVCs placed, L-asparaginase, heart failure, liver failure, and nephrotic syndrome. The final model using the set of variables selected by DAG analysis revealed LOS (OR = 1.106, 95%CI = 1.021–1.198, p = 0.013), L-asparaginase (OR = 26.463, 95%CI = 1.609–435.342, p = 0.022), and nephrotic syndrome (OR = 29.127, 95%CI = 1.044–812.508, p = 0.004) as independent risk factors for HA-VTE. Conclusion The DAG-based approach was useful to clarify the influence of confounders and multiple causalities of HA-VTE. Interestingly, CVC placement—a known thrombotic risk factor highlighted in several studies—was considered a confounder, while LOS, L-asparaginase use and nephrotic syndrome were confirmed as risk factors to HA-VTE. Large confidence intervals are related to the sample size; however, the results were significant.
-
risk factors for the development of hospital acquired pediatric venous thromboembolism dealing with potentially causal and confounding risk factors using directed acyclic graph dag analysis
medRxiv, 2020Co-Authors: Leonardo Campos, Mauricio Petroli, Flavio R Sztajnzbok, Elaine Sobral Da Costa, Leonardo R Brandao, Marcelo Gerardin Poirot LandAbstract:Abstract Introduction Hospital-acquired venous thromboembolism (HA-VTE) in children comprises multiple risk factors that should not be evaluated separately due to collinearity and multiple cause and effect relationships. This is one of the first case-control study of pediatric HA-VTE risk factors using directed acyclic graph (DAG) analysis. Material and Methods Retrospective, case-control study with 22 cases of radiologically proved HA-VTE and 76 controls matched by age, sex, unit of admission, and period of hospitalization. Descriptive statistics was used to define distributions of continuous variables, frequencies, and proportions of categorical variables, with a comparison between cases and controls. Due to many potential risk factors of HA-VTE, a directed acyclic graph (DAG) model was created to identify confounding, reduce bias, and increase precision on the analysis. The final model consisted of a DAG-based conditional logistic regression. The study was approved by the Institutional Review Board (CAAE 58056516.0.0000.5264). Results In the initial univariable model, the following variables were selected as potential risk factors for HA-VTE: length of stay (LOS, days), ICU admission in the last 30 days, LOS in ICU, infection, central venous catheter (CVC), L-asparaginase, heart failure, liver failure and nephrotic syndrome. The final model (table 1) revealed LOS (OR=1.108, 95%CI=1.024-1.199, p=0.011), L-asparaginase (OR=27.184, 95%CI=1.639-450.982, p=0.021), and nephrotic syndrome (OR=31.481, 95%CI=1.182-838.706, p=0.039) as independent risk factors for HA-VTE. Conclusion The DAG-based approach was useful to clarify the influence of confounders and multiple causalities of HA-VTE. Interestingly, CVC placement - a known thrombotic risk factor highlighted in several studies - was considered a confounder, while LOS, L-asparaginase use and nephrotic syndrome were confirmed as risk factors to HA-VTE. Large confidence intervals are related to the sample size, however the results were significant. Highlights HA-VTE comprises multiple risk factors that should not be evaluated separately due to collinearity and confounding directed acyclic graph (DAG) helps to clarify collinearity and confounding related to multiple cause and effect relationships that exist in HA-VTE risk factors This is a novel study using DAG-based logistic regression to evaluate risk factors for HA-VTE in children We reported the importance of medical conditions on the genesis of HA-VTE using a DAG-based approach, which makes it possible to clarify the influence of confounders and multiple causalities, such as catheter, a significant risk factor highlighted in several studies
Marcelo Gerardin Poirot Land - One of the best experts on this subject based on the ideXlab platform.
-
risk factors for the development of hospital acquired pediatric venous thromboembolism dealing with potentially causal and confounding risk factors using a directed acyclic graph dag analysis
PLOS ONE, 2020Co-Authors: Leonardo Campos, Mauricio Petroli, Elaine Sobral Da Costa, Leonardo R Brandao, Flavio Sztajnbok, Marcelo Gerardin Poirot LandAbstract:Introduction Hospital-acquired venous thromboembolism (HA-VTE) in children comprises multiple risk factors that should not be evaluated separately due to collinearity and multiple cause and effect relationships. This is one of the first case-control study of pediatric HA-VTE risk factors using a directed acyclic graph (DAG) analysis. Material and methods Retrospective, case-control study with 22 cases of objectively confirmed HA-VTE and 76 controls matched by age, sex, unit of admission, and period of hospitalization. Descriptive statistics were used to define distributions of continuous variables, frequencies, and proportions of categorical variables, comparing cases and controls. Due to many potential risk factors of HA-VTE, a directed acyclic graph (DAG) model was created to identify confounding, reduce bias, and increase precision on the analysis. The final model consisted of a DAG-informed conditional logistic regression. Results In the initial conventional univariable model, the following variables were selected as potential risk factors for HA-VTE: length of stay (LOS, days), immobility, ICU admission in the last 30 days, LOS in ICU, infection, central venous catheter (CVC), number of CVCs placed, L-asparaginase, heart failure, liver failure, and nephrotic syndrome. The final model using the set of variables selected by DAG analysis revealed LOS (OR = 1.106, 95%CI = 1.021–1.198, p = 0.013), L-asparaginase (OR = 26.463, 95%CI = 1.609–435.342, p = 0.022), and nephrotic syndrome (OR = 29.127, 95%CI = 1.044–812.508, p = 0.004) as independent risk factors for HA-VTE. Conclusion The DAG-based approach was useful to clarify the influence of confounders and multiple causalities of HA-VTE. Interestingly, CVC placement—a known thrombotic risk factor highlighted in several studies—was considered a confounder, while LOS, L-asparaginase use and nephrotic syndrome were confirmed as risk factors to HA-VTE. Large confidence intervals are related to the sample size; however, the results were significant.
-
risk factors for the development of hospital acquired pediatric venous thromboembolism dealing with potentially causal and confounding risk factors using directed acyclic graph dag analysis
medRxiv, 2020Co-Authors: Leonardo Campos, Mauricio Petroli, Flavio R Sztajnzbok, Elaine Sobral Da Costa, Leonardo R Brandao, Marcelo Gerardin Poirot LandAbstract:Abstract Introduction Hospital-acquired venous thromboembolism (HA-VTE) in children comprises multiple risk factors that should not be evaluated separately due to collinearity and multiple cause and effect relationships. This is one of the first case-control study of pediatric HA-VTE risk factors using directed acyclic graph (DAG) analysis. Material and Methods Retrospective, case-control study with 22 cases of radiologically proved HA-VTE and 76 controls matched by age, sex, unit of admission, and period of hospitalization. Descriptive statistics was used to define distributions of continuous variables, frequencies, and proportions of categorical variables, with a comparison between cases and controls. Due to many potential risk factors of HA-VTE, a directed acyclic graph (DAG) model was created to identify confounding, reduce bias, and increase precision on the analysis. The final model consisted of a DAG-based conditional logistic regression. The study was approved by the Institutional Review Board (CAAE 58056516.0.0000.5264). Results In the initial univariable model, the following variables were selected as potential risk factors for HA-VTE: length of stay (LOS, days), ICU admission in the last 30 days, LOS in ICU, infection, central venous catheter (CVC), L-asparaginase, heart failure, liver failure and nephrotic syndrome. The final model (table 1) revealed LOS (OR=1.108, 95%CI=1.024-1.199, p=0.011), L-asparaginase (OR=27.184, 95%CI=1.639-450.982, p=0.021), and nephrotic syndrome (OR=31.481, 95%CI=1.182-838.706, p=0.039) as independent risk factors for HA-VTE. Conclusion The DAG-based approach was useful to clarify the influence of confounders and multiple causalities of HA-VTE. Interestingly, CVC placement - a known thrombotic risk factor highlighted in several studies - was considered a confounder, while LOS, L-asparaginase use and nephrotic syndrome were confirmed as risk factors to HA-VTE. Large confidence intervals are related to the sample size, however the results were significant. Highlights HA-VTE comprises multiple risk factors that should not be evaluated separately due to collinearity and confounding directed acyclic graph (DAG) helps to clarify collinearity and confounding related to multiple cause and effect relationships that exist in HA-VTE risk factors This is a novel study using DAG-based logistic regression to evaluate risk factors for HA-VTE in children We reported the importance of medical conditions on the genesis of HA-VTE using a DAG-based approach, which makes it possible to clarify the influence of confounders and multiple causalities, such as catheter, a significant risk factor highlighted in several studies
Shuihua Wang - One of the best experts on this subject based on the ideXlab platform.
-
wavelet entropy and directed acyclic graph support vector machine for detection of patients with unilateral hearing loss in mri scanning
Frontiers in Computational Neuroscience, 2016Co-Authors: Shuihua Wang, Ming Yang, Jiquan Yang, Bin Liu, J M Gorriz, J Ramirez, Tifei YuanAbstract:(Aim) Sensorineural hearing loss (SNHL) is correlated to many neurodegenerative disease. Now more and more computer vision based methods are using to detect it in an automatic way. (Materials) We have in total 49 subjects, scanned by 3.0T MRI (Siemens Medical Solutions, Erlangen, Germany). The subjects contain 14 patients with right-sided hearing loss (RHL), 15 patients with left-sided hearing loss (LHL), and 20 healthy controls (HC). (Method) We treat this as a three-class classification problem: RHL, LHL, and HC. Wavelet entropy (WE) was selected from the magnetic resonance images of each subjects, and then submitted to a directed acyclic graph support vector machine (DAG-SVM). (Results) The 10 repetition results of 10-fold cross validation shows 3-level decomposition will yield an overall accuracy of 95.10% for this three-class classification problem, higher than feedforward neural network, decision tree, and naive Bayesian classifier. (Conclusions) This computer-aided diagnosis system is promising. We hope this study can attract more computer vision method for detecting hearing loss.
Yonghwan Kim - One of the best experts on this subject based on the ideXlab platform.
-
a self stabilizing algorithm for constructing a minimal reachable directed acyclic graph with two senders and two targets
Theoretical Computer Science, 2021Co-Authors: Yonghwan Kim, Masahiro Shibata, Yuichi Sudo, Junya Nakamura, Yoshiaki Katayama, Toshimitsu MasuzawaAbstract:Abstract In this paper, we introduce a new graph structure named an ST -reachable directed acyclic graph which is a directed acyclic graph (DAG) that guarantees reachability (i.e., a directed path exists) from every sender to every target. When an arbitrarily connected undirected graph G = ( V , E ) and two sets of the vertices, senders S (⊂V) and targets T (⊂V), are given, we consider the construction of a minimal ST -reachable DAG by changing some undirected edges to arcs and removing the remaining edges. In this paper, we present the necessary and sufficient condition under which a minimal ST -reachable DAG can be constructed when | S | ≤ 2 and | T | ≤ 2 , and propose a self-stabilizing algorithm for constructing a minimal ST -reachable DAG (if it exists) when an arbitrarily connected undirected graph, S ( | S | ≤ 2 ) and T ( | T | ≤ 2 ) are given. Moreover, our proposed algorithm can detect the non-existence of any ST -reachable DAG if the ST -reachable DAG of the given graph and two sets of vertices, S and T , do not exist.
-
self stabilizing construction of a minimal weakly st reachable directed acyclic graph
Symposium on Reliable Distributed Systems, 2020Co-Authors: Junya Nakamura, Yuichi Sudo, Masahiro Shibata, Yonghwan KimAbstract:We propose a self-stabilizing algorithm to construct a minimal weakly ST-reachable directed acyclic graph (DAG), which is suited for routing messages on wireless networks. Given an arbitrary, simple, connected, and undirected graph $G=(V,\ E)$ and two sets of nodes, senders $S(\subset V)$ and targets $T(\subset V)$, a directed subgraph $\vec{G}$ of G is a weakly ST-reachable DAG on G, if $\vec{G}$ is a DAG and every sender can reach at least one target, and every target is reachable from at least one sender in $\vec{G}$. We say that a weakly ST-reachable DAG $\vec{G}$ on G is minimal if any proper subgraph of $\vec{G}$ is no longer a weakly ST-reachable DAG. This DAG is a relaxed version of the original (or strongly) ST-reachable DAG, where every target is reachable from every sender. This is because a strongly ST reachable DAG G does not always exist; some graph has no strongly ST-reachable DAG even in the case $|S|=|T|=2$. On the other hand, the proposed algorithm always constructs a weakly ST-reachable DAG for any $|S|$ and $|T|$. Furthermore, the proposed algorithm is self-stabilizing; even if the constructed DAG deviates from the reachability requirement by a breakdown or exhausting the battery of a node having an arc in the DAG, this algorithm automatically reconstructs the DAG to satisfy the requirement again. The convergence time of the algorithm is O(D) asynchronous rounds, where D is the diameter of a given graph. We conduct small simulations to evaluate the performance of the proposed algorithm. The simulation result indicates that its execution time decreases when the number of sender nodes or target nodes is large.
-
a self stabilizing algorithm for constructing st reachable directed acyclic graph when ls 2 and t 2
International Conference on Distributed Computing Systems, 2019Co-Authors: Yonghwan Kim, Masahiro Shibata, Yuichi Sudo, Junya Nakamura, Yoshiaki Katayama, Toshimitsu MasuzawaAbstract:In this paper, we introduce a new graph structure named an ST-reachable directed acyclic graph which is a directed acyclic graph (DAG) that guarantees reachability from every sender to every target (i.e., a directed path exists). When an arbitrary connected undirected graph G=(V,E) and two sets of the vertices, senders S (⊂ V) and targets T (⊂ V), are given, we consider construction of a minimal ST-reachable DAG by changing some undirected edges to arcs and removing the remaining edges. This implies that every node in T is reachable from every node in S on the constructed ST-reachable DAG. In particular, our goals are (1) to find the necessary and sufficient condition that an ST-reachable DAG can be constructed, and (2) to design a self-stabilizing algorithm for constructing a minimal ST-reachable DAG (if exists). In this paper, we present the necessary and sufficient condition that a minimal ST-reachable DAG can be constructed when S ≤ 2 and |T| ≤ 2, and propose a self-stabilizing algorithm to construct an ST-reachable DAG (if exists) when an arbitrary connected undirected graph, S (|S| ≤ 2) and T (|T| ≤ 2) are given. Moreover, our proposed algorithm can detect the non-existence of ST-reachable DAG if there exists no ST-reachable DAG of the given graph and two sets of vertices, S and T.
Junya Nakamura - One of the best experts on this subject based on the ideXlab platform.
-
a self stabilizing algorithm for constructing a minimal reachable directed acyclic graph with two senders and two targets
Theoretical Computer Science, 2021Co-Authors: Yonghwan Kim, Masahiro Shibata, Yuichi Sudo, Junya Nakamura, Yoshiaki Katayama, Toshimitsu MasuzawaAbstract:Abstract In this paper, we introduce a new graph structure named an ST -reachable directed acyclic graph which is a directed acyclic graph (DAG) that guarantees reachability (i.e., a directed path exists) from every sender to every target. When an arbitrarily connected undirected graph G = ( V , E ) and two sets of the vertices, senders S (⊂V) and targets T (⊂V), are given, we consider the construction of a minimal ST -reachable DAG by changing some undirected edges to arcs and removing the remaining edges. In this paper, we present the necessary and sufficient condition under which a minimal ST -reachable DAG can be constructed when | S | ≤ 2 and | T | ≤ 2 , and propose a self-stabilizing algorithm for constructing a minimal ST -reachable DAG (if it exists) when an arbitrarily connected undirected graph, S ( | S | ≤ 2 ) and T ( | T | ≤ 2 ) are given. Moreover, our proposed algorithm can detect the non-existence of any ST -reachable DAG if the ST -reachable DAG of the given graph and two sets of vertices, S and T , do not exist.
-
self stabilizing construction of a minimal weakly st reachable directed acyclic graph
Symposium on Reliable Distributed Systems, 2020Co-Authors: Junya Nakamura, Yuichi Sudo, Masahiro Shibata, Yonghwan KimAbstract:We propose a self-stabilizing algorithm to construct a minimal weakly ST-reachable directed acyclic graph (DAG), which is suited for routing messages on wireless networks. Given an arbitrary, simple, connected, and undirected graph $G=(V,\ E)$ and two sets of nodes, senders $S(\subset V)$ and targets $T(\subset V)$, a directed subgraph $\vec{G}$ of G is a weakly ST-reachable DAG on G, if $\vec{G}$ is a DAG and every sender can reach at least one target, and every target is reachable from at least one sender in $\vec{G}$. We say that a weakly ST-reachable DAG $\vec{G}$ on G is minimal if any proper subgraph of $\vec{G}$ is no longer a weakly ST-reachable DAG. This DAG is a relaxed version of the original (or strongly) ST-reachable DAG, where every target is reachable from every sender. This is because a strongly ST reachable DAG G does not always exist; some graph has no strongly ST-reachable DAG even in the case $|S|=|T|=2$. On the other hand, the proposed algorithm always constructs a weakly ST-reachable DAG for any $|S|$ and $|T|$. Furthermore, the proposed algorithm is self-stabilizing; even if the constructed DAG deviates from the reachability requirement by a breakdown or exhausting the battery of a node having an arc in the DAG, this algorithm automatically reconstructs the DAG to satisfy the requirement again. The convergence time of the algorithm is O(D) asynchronous rounds, where D is the diameter of a given graph. We conduct small simulations to evaluate the performance of the proposed algorithm. The simulation result indicates that its execution time decreases when the number of sender nodes or target nodes is large.
-
a self stabilizing algorithm for constructing st reachable directed acyclic graph when ls 2 and t 2
International Conference on Distributed Computing Systems, 2019Co-Authors: Yonghwan Kim, Masahiro Shibata, Yuichi Sudo, Junya Nakamura, Yoshiaki Katayama, Toshimitsu MasuzawaAbstract:In this paper, we introduce a new graph structure named an ST-reachable directed acyclic graph which is a directed acyclic graph (DAG) that guarantees reachability from every sender to every target (i.e., a directed path exists). When an arbitrary connected undirected graph G=(V,E) and two sets of the vertices, senders S (⊂ V) and targets T (⊂ V), are given, we consider construction of a minimal ST-reachable DAG by changing some undirected edges to arcs and removing the remaining edges. This implies that every node in T is reachable from every node in S on the constructed ST-reachable DAG. In particular, our goals are (1) to find the necessary and sufficient condition that an ST-reachable DAG can be constructed, and (2) to design a self-stabilizing algorithm for constructing a minimal ST-reachable DAG (if exists). In this paper, we present the necessary and sufficient condition that a minimal ST-reachable DAG can be constructed when S ≤ 2 and |T| ≤ 2, and propose a self-stabilizing algorithm to construct an ST-reachable DAG (if exists) when an arbitrary connected undirected graph, S (|S| ≤ 2) and T (|T| ≤ 2) are given. Moreover, our proposed algorithm can detect the non-existence of ST-reachable DAG if there exists no ST-reachable DAG of the given graph and two sets of vertices, S and T.