In a crowded harbor water area, it is a major concern to control ship traffic for assuring safety and maximizing the efficiency of port operations. Vessel Traffic Service (VTS) operators pay much ...attention to caution areas like ship route intersections or traffic congestion area in which there are some risks of ship collision. They want to control the traffic of the caution area at a proper level to lessen risk. Inertial ship movement makes swift changes in direction and speed difficult. It is hence important to predict future traffic of the caution area earlier on so as to get enough time for control actions on ship movements. In the harbor area, VTS stations collect a large volume of Automatic Identification Service (AIS) sensor data, which contain information about ship movement and ship attributes. This paper proposes a new deep neural network model called Ship Traffic Extraction Network (STENet) to predict the medium-term traffic and long-term traffic of the caution area. The STENet model is trained with AIS sensor data. The STENet model is organized into a hierarchical architecture in which the outputs of the movement and contextual feature extraction modules are concatenated and fed into a prediction module. The movement module extracts the features of overall ship movements with a convolutional neural network. The contextual modules consist of five separated fully-connected neural networks, each of which receives an associated attribute. The separation of feature extraction modules at the front phase helps extract the effective features by preventing unrelated attributes from crosstalking. To evaluate the performance of the proposed model, the developed model is applied to a real AIS sensor dataset, which has been collected over two years at a Korean port called Yeosu. In the experiments, four methods have been compared including two new methods: STENet and VGGNet-based models. For the real AIS sensor dataset, the proposed model has shown 50.65% relative performance improvement on average for the medium-term predictions and 57.65% improvement on average for the long-term predictions over the benchmark method, i.e., the SVR-based method.
Many real-world complex systems are best modeled by multiplex networks of interacting network layers. The multiplex network study is one of the newest and hottest themes in the statistical physics of ...complex networks. Pioneering studies have proven that the multiplexity has broad impact on the system’s structure and function. In this Colloquium paper, we present an organized review of the growing body of current literature on multiplex networks by categorizing existing studies broadly according to the type of layer coupling in the problem. Major recent advances in the field are surveyed and some outstanding open challenges and future perspectives will be proposed.
Patients with hypertension are at higher risk for dementia than the general population. We sought to understand the relative importance of various risk factors in the development of dementia among ...patients with hypertension. This population-based cohort study used data from the Korean National Insurance Service database. Using the Cox proportional hazard model, R2 values for each potential risk factor were calculated to test the relative importance of risk factors for the development of dementia. Eligible individuals were adults 40 to 79 years of age with hypertension and without a history of stroke and dementia between 2007 and 2009. A total of 650,476 individuals (mean age, 60 ± 11 years) with hypertension were included in the analyses. During a mean follow-up of 9.5 years (±2.8 years), 57,112 cases of dementia were observed. The three strongest predictors of dementia were age, comorbidity burden (assessed using the Charlson Comorbidity Index), and female sex (R2 values, 0.0504, 0.0023, and 0.0022, respectively). The next strongest risk factors were physical inactivity, smoking, alcohol consumption, and obesity (R2 values, 0.00070, 0.00024, 0.00021, and 0.00020, respectively). Across all age groups, physical inactivity was an important risk factor for dementia occurrence. In summary, controlling and preventing comorbidities are of utmost importance to prevent dementia in patients with hypertension. More efforts should be taken to encourage physical activity among patients with hypertension across all age groups. Furthermore, smoking cessation, avoiding and limiting alcohol consumption, and maintaining an appropriate body weight are urged to prevent dementia.
In this study, position-independent geometric errors, including offset errors and squareness errors of rotary axes of a five-axis machine tool are measured using a double ball-bar and are verified ...through compensation. In addition, standard uncertainties of measurement results are calculated to establish their confidence intervals. This requires two measurement paths for each rotary axis, which are involving control of single rotary axis during measurement. So, the measurement paths simplify the measurement process, and reduce measurement cost including less operator effort and measurement time. Set-up errors, which are inevitable during the installation of the balls, are modeled as constants. Their effects on the measurement results are investigated to improve the accuracy of the measurement result. A novel fixture consisting of flexure hinges and two pairs of bolts is used to minimize set-up error by adjusting the ball's position located at the tool nose. Simulation is performed to check the validation of measurement and to analyze the standard uncertainties of the measurement results. Finally, the position-independent geometric errors of the five-axis machine tool (involving a rotary axis and a trunnion axis) are measured using proposed method.
•PIGEs of a five-axis machine tool are measured using a double ball-bar.•Simple measurement paths are developed to decrease measurement cost.•Set-up errors are investigated and minimized by using novel fixture.•Measurement uncertainty of measured PIGEs is established for confidence interval.
The rock core test is the most direct and reliable way to measure fundamental physical, hydraulic, and mechanical properties for underground reservoir characterization. A 10-cm diameter and ...3.6-m-long granodiorite core was retrieved from a 4.2-km-deep geothermal well at the Pohang Enhanced Geothermal System (EGS) site in Korea. Numerous natural fractures were detected in the core and induced core disks were observed. We optimized the sample preparation with this limited core for various tests based on the scanned X-ray CT images that visualized all the fractures in the core. We measured the basic mechanical—the deformation and strength properties of intact rock—and thermal properties of intact samples. In particular, fracture deformation and strength properties were directly measured by conducting direct shear tests on pre-existing natural fractures. The seismic velocity and normal fracture stiffness were compared with the wireline logging and injection test measurements, respectively. The discrepancies between the in situ data and laboratory experiment are due to the stress dependency of properties. The measurements presented in this paper provide essential inputs for the EGS reservoir modelling and a dataset of properties for the fractured granite reservoir at a great depth from which few samples have been retrieved thus far.
(k,q)-core decomposition of hypergraphs Lee, Jongshin; Goh, Kwang-Il; Lee, Deok-Sun ...
Chaos, solitons and fractals,
August 2023, 2023-08-00, Volume:
173
Journal Article
Peer reviewed
Open access
In complex networks, many elements interact with each other in different ways. A hypergraph is a network in which group interactions occur among more than two elements. In this study, first, we ...propose a method to identify influential subgroups in hypergraphs, named (k,q)-core decomposition. The (k,q)-core is defined as the maximal subgraph in which each vertex has at least k hypergraph degrees and each hyperedge contains at least q vertices. The method contains a repeated pruning process until reaching the (k,q)-core, which shares similarities with a widely used k-core decomposition technique in a graph. Second, we analyze the pruning dynamics and the percolation transition with theoretical and numerical methods in random hypergraphs. We set up evolution equations for the pruning process, and self-consistency equations for the percolation properties. Based on our theory, we find that the pruning process generates a hybrid percolation transition for either k≥3orq≥3. The critical exponents obtained theoretically are confirmed with finite-size scaling analysis. Next, when k=q=2, we obtain a unconventional degree-dependent critical relaxation dynamics analytically and numerically. Finally, we apply the (k,q)-core decomposition to a real coauthorship dataset and recognize the leading groups at an early stage.
•A pruning process to obtain the core structure of hypergraphs is proposed.•Theoretical methods to analyze (k,q)-core decomposition are proposed.•The percolation transition of the giant core is studied analytically and numerically.•Degree-dependent power-law behaviors of relaxation dynamics are obtained.•Our method suggests an effective way to select influential subgroup in hypergraphs.
In patients with hypertension, left ventricular hypertrophy (LVH) represents a risk factor for cardiovascular disease and asymptomatic organ damage. Currently, electrocardiography (ECG) and ...two‐dimensional echocardiography (Echo) are the most widely used methods for LVH evaluation. This study aimed to compare the long‐term outcomes of LVH, as evaluated by ECG and Echo, in patients with hypertension. Patients diagnosed with hypertension as a primary disease between 2006 and 2011 were enrolled in the Korean Hypertension Cohort study. The study finally included 1743 patients who underwent both ECG and Echo. The primary endpoint was defined as the composite of major adverse cardiovascular events (MACEs) or death. Overall, LVH was identified in 747 patients. The patients were categorized into four groups according to the detection of LVH by ECG or Echo: No LVH (n = 996), LVH diagnosed by ECG alone (n = 181), LVH diagnosed by Echo alone (n = 415), LVH diagnosed by both ECG and Echo (n = 151). After adjusting for variables, the incidence of MACEs or death was significantly greater in patients with LVH diagnosed by ECG alone (hazards ratio HR: 1.69; 95% confidence interval CI: 1.22–2.35; P = .001), LVH diagnosed by Echo alone (HR: 1.54; 95% CI: 1.16–2.05; P = .002), and LVH diagnosed by both ECG and Echo (HR: 1.87; 95% CI: 1.18–2.94; P = .002) than in those with no LVH. Both ECG and Echo are efficient diagnostic tools for LVH and useful for long‐term risk stratification. Additional Echo evaluation for LVH is helpful for predicting long‐term outcomes only in patients without LVH diagnosis by ECG.
Background
Polypharmacy is an important issue in the care of older patients with cancer, as it increases the risk of unfavorable outcomes. We estimated the prevalence of polypharmacy, potentially ...inappropriate medication (PIM) use, and drug–drug interactions (DDIs) in older patients with cancer in Korea and their associations with clinical outcomes.
Subjects, Materials, and Methods
This was a secondary analysis of a prospective observational study of geriatric patients with cancer undergoing first‐line palliative chemotherapy. Eligible patients were older adults (≥70 years) with histologically diagnosed solid cancer who were candidates for first‐line palliative chemotherapy. All patients enrolled in this study received a geriatric assessment (GA) at baseline. We reviewed the daily medications taken by patients at the time of GA before starting chemotherapy. PIMs were assessed according to the 2015 Beers criteria, and DDIs were assessed by a clinical pharmacist using Lexi‐comp Drug Interactions. We evaluated the association between polypharmacy and clinical outcomes including treatment‐related toxicity, and hospitalization using logistic regression and Cox regression analyses.
Results
In total, 301 patients (median age 75 years; range, 70–93) were enrolled; the most common cancer types were colorectal cancer (28.9%) and lung cancer (24.6%). Mean number of daily medications was 4.7 (±3.1; range, 0–14). The prevalence of polypharmacy (≥5 medications) was 45.2% and that of excessive polypharmacy (≥10 medications) was 8.6%. PIM use was detected in 137 (45.5%) patients. Clinically significant DDIs were detected in 92 (30.6%) patients. Polypharmacy was significantly associated with hospitalization or emergency room (ER) visits (odds ratio: 1.73 1.18–2.55, p < .01). Neither polypharmacy nor PIM use showed association with treatment‐related toxicity.
Conclusion
Polypharmacy, PIM use, and potential major DDIs were prevalent in Korean geriatric patients with cancer. Polypharmacy was associated with a higher risk of hospitalization or ER visits during the chemotherapy period.
Implications for Practice
This study, which included 301 older Korean patients with cancer, highlights the increased prevalence of polypharmacy in this population planning to receive palliative chemotherapy. The prevalence of polypharmacy and excessive polypharmacy was 45.2% and 8.6%, respectively. The prescription of potentially inappropriate medications (PIMs) was detected in 45.5% and clinically significant drug–drug interaction in 30.6% of patients. Given the association of polypharmacy with increased hospitalization or emergency room visits, this study points to the need for increased awareness and intervention to minimize polypharmacy in the geriatric cancer population undergoing chemotherapy. Moreover, specific criteria for establishing PIMs should be adopted for the treatment of older adults with cancer.
There is limited information on polypharmacy in Asian older adults with metastatic cancer, especially for those undergoing palliative chemotherapy. This article reports on the prevalence of polypharmacy, potentially inappropriate medication use, and potential drug‐drug interactions in older patients with cancer in Korea.
With evaluation for physical performance, measuring muscle mass is an important step in detecting sarcopenia. However, there are no methods to estimate muscle mass from blood sampling.
To develop a ...new equation to estimate total-body muscle mass with serum creatinine and cystatin C level, we designed a cross-sectional study with separate derivation and validation cohorts. Total body muscle mass and fat mass were measured using dual-energy x-ray absorptiometry (DXA) in 214 adults aged 25 to 84 years who underwent physical checkups from 2010 to 2013 in a single tertiary hospital. Serum creatinine and cystatin C levels were also examined.
Serum creatinine was correlated with muscle mass (P < .001), and serum cystatin C was correlated with body fat mass (P < .001) after adjusting glomerular filtration rate (GFR). After eliminating GFR, an equation to estimate total-body muscle mass was generated and coefficients were calculated in the derivation cohort. There was an agreement between muscle mass calculated by the novel equation and measured by DXA in both the derivation and validation cohort (P < .001, adjusted R2 = 0.829, β = 0.95, P < .001, adjusted R2 = 0.856, β = 1.03, respectively).
The new equation based on serum creatinine and cystatin C levels can be used to estimate total-body muscle mass.
Abstract
To understand the mechanism behind high-
z
Ly
α
nebulae, we simulate the scattering of Ly
α
in a H
i
halo about a central Ly
α
source. For the first time, we consider both smooth and clumpy ...distributions of halo gas, as well as a range of outflow speeds, total H
i
column densities, H
i
spatial concentrations, and central source galaxies (e.g., with Ly
α
line widths corresponding to those typical of active galactic nucleus or star-forming galaxies). We compute the spatial-frequency diffusion and the polarization of the Ly
α
photons scattered by atomic hydrogen. Our scattering-only model reproduces the typical size of Ly
α
nebulae (∼100 kpc) at total column densities
N
H I
≥ 10
20
cm
−2
and predicts a range of positive, flat, and negative polarization radial gradients. We also find two general classes of Ly
α
nebula morphologies: with and without bright cores. Cores are seen when
N
H I
is low, i.e., when the central source is directly visible, and are associated with a polarization jump, a steep increase in the polarization radial profile just outside the halo center. Of all the parameters tested in our smooth or clumpy medium model,
N
H I
dominates the trends. The radial behaviors of the Ly
α
surface brightness, spectral line shape, and polarization in the clumpy model with covering factor
f
c
≳ 5 approach those of the smooth model at the same
N
H I
. A clumpy medium with high
N
H I
and low
f
c
≲ 2 generates Ly
α
features via scattering that the smooth model cannot: a bright core, symmetric line profile, and polarization jump.
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