Hypergraph Motifs and Their Extensions Beyond Binary

Hypergraphs naturally represent group interactions, which are omnipresent in many domains: collaborations of researchers, co-purchases of items, and joint interactions of proteins, to name a few. In this work, we propose tools for answering the following questions: (Q1) what are the structural design principles of real-world hypergraphs? (Q2) how can we compare local structures of hypergraphs of different sizes? (Q3) how can we identify domains from which hypergraphs are? We first define hypergraph motifs (h-motifs), which describe the overlapping patterns of three connected hyperedges. Then, we define the significance of each h-motif in a hypergraph as its occurrences relative to those in properly randomized hypergraphs. Lastly, we define the characteristic profile (CP) as the vector of the normalized significance of every h-motif. Regarding Q1, we find that h-motifs' occurrences in 11 real-world hypergraphs from 5 domains are clearly distinguished from those of randomized hypergraphs. Then, we demonstrate that CPs capture local structural patterns unique to each domain, and thus comparing CPs of hypergraphs addresses Q2 and Q3. The concept of CP is extended to represent the connectivity pattern of each node or hyperedge as a vector, which proves useful in node classification and hyperedge prediction. Our algorithmic contribution is to propose MoCHy, a family of parallel algorithms for counting h-motifs' occurrences in a hypergraph. We theoretically analyze their speed and accuracy and show empirically that the advanced approximate version MoCHy-A+ is more accurate and faster than the basic approximate and exact versions, respectively. Furthermore, we explore ternary hypergraph motifs that extends h-motifs by taking into account not only the presence but also the cardinality of intersections among hyperedges. This extension proves beneficial for all previously mentioned applications.Comment: Extended version of VLDB 2020 paper arXiv:2003.0185

Dual-phase F-18-florbetaben PET provides cerebral perfusion proxy along with beta-amyloid burden in Alzheimer's disease

BACKGROUND: This study investigated changes in brain perfusion and Aβ burden according to the progression of Alzheimer's disease (AD) by using a dual-phase 18F-florbetaben (FBB) PET protocol. METHODS: Sixty subjects, including 12 with Aβ-negative normal cognition (Aβ-NC), 32 with Aβ-positive mild cognitive impairment (Aβ+MCI), and 16 with Aβ-positive AD (Aβ+AD), were enrolled. A dynamic PET scan was obtained in the early phase (0-10 min, eFBB) and delayed phase (90-110 min, dFBB), which were then averaged into a single frame, respectively. In addition to the averaged eFBB, an R1 parametric map was calculated from the eFBB scan based on a simplified reference tissue model (SRTM). Between-group regional and voxel-wise analyses of the images were performed. The associations between cognitive profiles and PET-derived parameters were investigated. RESULTS: Both the R1 and eFBB perfusion reductions in the cortical regions were not significantly different between the Aβ-NC and Aβ+MCI groups, while they were significantly reduced from the Aβ+MCI to Aβ+AD groups in regional and voxel-wise analyses. However, cortical Aβ depositions on dFBB were not significantly different between the Aβ+MCI and Aβ+AD groups. There were strong positive correlations between the R1 and eFBB images in regional and voxel-wise analyses. Both perfusion components showed significant correlations with general and specific cognitive profiles. CONCLUSION: The results of this study demonstrated the feasibility of dual-phase 18F-FBB PET to evaluate different trajectories of dual biomarkers for neurodegeneration and Aβ burden over the course of AD. In addition, both eFBB and SRTM-based R1 can provide robust indices of brain perfusion

Monte Carlo simulation study of an in vivo four-dimensional tracking system with a diverging collimator for monitoring radiation source (Ir-192) location during brachytherapy: proof of concept and feasibility

Introduction: The aim of this study was to demonstrate the potential of an in vivo four-dimensional (4D) tracking system to accurately localize the radiation source, Iridium-192 (Ir-192) in high-dose rate brachytherapy.Methods: To achieve time-dependent 3D positioning of the Ir-192 source, we devised a 4D tracking system employing multiple compact detectors. During the system’s design phase, we conducted comprehensive optimization and analytical evaluations of the diverging collimator employed for detection purposes. Subsequently, we executed 3D reconstruction and positioning procedures based on the 2D images obtained by six detectors, each equipped with an optimized diverging collimator. All simulations for designing and evaluating the 4D tracking system were performed using the open-source GATE (v9.1) Monte Carlo platform based on the GEANT4 (v10.7) toolkit. In addition, to evaluate the accuracy of the proposed 4D tracking system, we conducted simulations and 3D positioning using a solid phantom and patient data. Finally, the error between the reconstructed position coordinates determined by the tracking system and the original coordinates of the Ir-192 radiation source was analyzed.Results: The parameters for the optimized diverging collimator were a septal thickness of 0.3 mm and a collimator height of 30 mm. A tracking system comprising 6 compact detectors was designed and implemented utilizing this collimator. Analysis of the accuracy of the proposed Ir-192 source tracking system found that the average of the absolute values of the error between the 3D reconstructed and original positions for the simulation with the solid phantom were 0.440 mm for the x coordinate, 0.423 mm for the y coordinate, and 0.764 mm for the z coordinate, and the average Euclidean distance was 1.146 mm. Finally, in a simulation based on data from a patient who underwent brachytherapy, the average Euclidean distance between the original and reconstructed source position was 0.586 mm.Discussion: These results indicated that the newly designed in vivo 4D tracking system for monitoring the Ir-192 source during brachytherapy could determine the 3D position of the radiation source in real time during treatment. We conclude that the proposed positioning system has the potential to make brachytherapy more accurate and reliable

The BDNF Val66Met Polymorphism Affects the Vulnerability of the Brain Structural Network

Val66Met, a naturally occurring polymorphism in the human brain-derived neurotrophic factor (BDNF) gene resulting in a valine (Val) to methionine (Met) substitution at codon 66, plays an important role in neuroplasticity. While the effect of the BDNF Val66Met polymorphism on local brain structures has previously been examined, its impact on the configuration of the graph-based white matter structural networks is yet to be investigated. In the current study, we assessed the effect of the BDNF polymorphism on the network properties and robustness of the graph-based white matter structural networks. Graph theory was employed to investigate the structural connectivity derived from white matter tractography in two groups, Val homozygotes (n = 18) and Met-allele carriers (n = 55). Although there were no differences in the global network measures including global efficiency, local efficiency, and modularity between the two genotype groups, we found the effect of the BDNF Val66Met polymorphism on the robustness properties of the white matter structural networks. Specifically, the white matter structural networks of the Met-allele carrier group showed higher vulnerability to targeted removal of central nodes as compared with those of the Val homozygote group. These findings suggest that the central role of the BDNF Val66Met polymorphism in regards to neuroplasticity may be associated with inherent differences in the robustness of the white matter structural network according to the genetic variants. Furthermore, greater susceptibility to brain disorders in Met-allele carriers may be understood as being due to their limited stability in white matter structural connectivity

Epidemiologic survey of head and neck cancers in Korea.

Head and neck cancers have never been systematically studied for clinical purposes yet in Korea. This epidemiological survey on head and neck cancer patients was undertaken from January to December 2001 in 79 otorhinolaryngology resident-training hospitals nationwide. The number of head and neck cancer patients was 1,063 cases in the year. The largest proportion of cases arose in the larynx, as many as 488 cases, which accounted for 45.9%. It was followed by, in order of frequency, oral cavity (16.5%), oropharynx (10.0%), and hypopharynx (9.5%). The male:female ratio was 5:1, and the mean age was 60.3 yr. Surgery was the predominant treatment modality in head and neck cancers: 204 (21.5%) cases were treated with only surgery, 198 (20.8%) cases were treated with surgery and radiotherapy, 207 cases (21.8%) were treated with combined therapy of surgery, radiotherapy, and chemotherapy. Larynx and hypopharynx cancers had a stronger relationship with smoking and alcohol drinking than other primary site cancers. Of them, 21 cases were found to be metastasized at the time of diagnosis into the lung, gastrointestinal tract, bone, or brain. Coexisting second primary malignancies were found in 23 cases. At the time of diagnosis, a total of 354 cases had cervical lymph node metastasis accounting for 42.0%

Analysis of Hemodialysis-Associated Hypoglycemia in Patients with Type 2 Diabetes Using a Continuous Glucose Monitoring System

Background: Adequate glycemic control is important for patients with end-stage renal disease on maintenance hemodialysis (HD). Continuous glucose monitoring (CGM) systems are reported as a useful method for glucose monitoring in patients under maintenance HD. The object of this study was to describe glucose profiles and hypoglycemia associated with HD in diabetes patients using a CGM system. Methods: We recruited nine medically stable patients with type 2 diabetes under maintenance HD. CGMS (R) System Gold (R) (Medtronic MiniMed, Northridge, CA) was applied to the subjects for 144 h. During the period, HD using glucose-containing dialysate was performed every other day. Various glucose profiles were calculated from the CGM readings and compared between the day on and the day off dialysis. Results: Mean +/- SD for age, duration of diabetes, and hemoglobin A1c were 67 +/- 9 years, 24 +/- 9 years, and 8.6 +/- 1.2%, respectively. Hemoglobin A1c was correlated with mean glucose (rho = 0.780, P < 0.05) and with area under the curve for glucose above 180 mg/ dL (rho = 0.797, P < 0.05). Although there was no difference for mean amplitude of glycemic excursion between the day on and off HD, hypoglycemia occurred predominantly with day on HD. In the subjects who maintained antidiabetes agents with day on HD, glucose levels decreased with initiation of HD, causing significantly lower glucose levels compared to those during the equivalent time of the following day without HD. Conclusions: According to the CGM system, glucose variability was not affected by HD. However, in spite of glucose-containing dialysate, HD seemed to increase the risk of hypoglycemia.This study was supported by a grant from the Korea Science and Engineering Foundation (KOSEF) (0521-20080010) by the Ministry of Education, Science and Technology (MEST), by a grant from the Innovative Research Institute for Cell Therapy (A062260) by the Ministry of Health and Welfare, Republic of Korea, and by WCU project (R31-2008-000- 10103-0) of the MEST and the KOSEF.*INT DIAB FED, 2010, DIAB ATL*AM DIAB ASS, 2010, DIABETES CARE S1, V33, pS4Drechsler C, 2009, CIRCULATION, V120, P2421, DOI 10.1161/CIRCULATIONAHA.109.857268Riveline JP, 2009, NEPHROL DIAL TRANSPL, V24, P2866, DOI 10.1093/ndt/gfp181Kazempour-Ardebili S, 2009, DIABETES CARE, V32, P1137, DOI 10.2337/dc08-1688Kohnert KD, 2009, DIABETES CARE, V32, P1058, DOI 10.2337/dc08-1956SHIM Y, 2009, KOREAN J NUTR, V42, P577Tamborlane WV, 2008, NEW ENGL J MED, V359, P1464Wentholt IME, 2008, DIABETOLOGIA, V51, P183, DOI 10.1007/s00125-007-0842-6*US REN DAT SYST, 2008, USRSD 2008 ANN DAT RKohnert KD, 2007, DIABETES RES CLIN PR, V77, P420, DOI 10.1016/j.diabres.2007.01.021Burmeister JE, 2007, NEPHROL DIAL TRANSPL, V22, P1184, DOI 10.1093/ndt/gfl710Williams ME, 2006, KIDNEY INT, V70, P1503, DOI 10.1038/sj.ki.5001789Monnier L, 2006, JAMA-J AM MED ASSOC, V295, P1681Sangill M, 2006, AM J KIDNEY DIS, V47, P636, DOI 10.1053/j.ajkd.2006.01.007Rigalleau V, 2005, CURR OPIN CLIN NUTR, V8, P463Childs BP, 2005, DIABETES CARE, V28, P1245TANSEY MJ, 2005, DIABETES TECHNOL THE, V7, P109Loipl J, 2005, RENAL FAILURE, V27, P305, DOI 10.1081/JDI-200056608Cryer PE, 2003, DIABETES CARE, V26, P1902Djakoure-Platonoff C, 2003, DIABETES METAB, V29, P159Guerci B, 2003, DIABETES CARE, V26, P582*DIRECNET STUD GRO, 2003, DIABETES TECHNOL THE, V5, P781Boland E, 2001, DIABETES CARE, V24, P1858Morioka T, 2001, DIABETES CARE, V24, P909Kovatchev BP, 2000, J CLIN ENDOCR METAB, V85, P4287Jackson MA, 2000, CLIN NEPHROL, V54, P30Haviv YS, 2000, RENAL FAILURE, V22, P219Mastrototaro J, 1999, J PEDIATR ENDOCR MET, V12, P751Nakao T, 1998, INTERNAL MED, V37, P8261998, LANCET, V352, P837Davis SN, 1997, DIABETES, V46, P1328Morgan L, 1996, DIABETIC MED, V13, P5141993, N ENGL J MED, V329, P977MITRAKOU A, 1991, AM J PHYSIOL, V260, pE67DEFEO P, 1988, J CLIN INVEST, V82, P436SCHWARTZ NS, 1987, J CLIN INVEST, V79, P777SERVICE FJ, 1970, DIABETES, V19, P644

A planar, via-less zeroth-order antenna for wearable electrocardiography

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