Graph Matching in Correlated Stochastic Block Models for Improved Graph Clustering

We consider community detection from multiple correlated graphs sharing the same community structure. The correlated graphs are generated by independent subsampling of a parent graph sampled from the stochastic block model. The vertex correspondence between the correlated graphs is assumed to be unknown. We consider the two-step procedure where the vertex correspondence between the correlated graphs is first revealed, and the communities are recovered from the union of the correlated graphs, which becomes denser than each single graph. We derive the information-theoretic limits for exact graph matching in general density regimes and the number of communities, and then analyze the regime of graph parameters, where one can benefit from the matching of the correlated graphs in recovering the latent community structure of the graphs.Comment: Allerton Conference 202

THE ATTACHMENT AND CHARACTERIZATION OF DNA PROBES ON GaAs-BASED SEMICONDUCTOR SURFACES

Immobilization of nucleic acid molecules on solid surfaces is the core of numerous important technologies in the genomics, disease diagnostics and biosensors applications. The architecture and density of immobilized probe molecules depend on the type of the solid surface on which they are anchored. Even though many different types of surfaces have been studied as substrates for deoxyribonucleic acid (DNA) attachment, the development of a new type of substrate, which is reproducible, stable, highly controlled and easily transferred to practical applications, is still needed. Recent studies have shown that As terminated GaAs-based semiconductors can be used as substrates for immobilized DNA layers. In this study, I aim to understand the attachment of nucleic acid onto the surfaces of As-terminated GaAs- based semiconductors and focus on improving the "brush-structure", which is essential for high quality of biochip based on a DNA layer. Attachment of 8-base and 100-base thiolated ssDNA layers on arsenic terminated GaAs(001) was achieved and characterized. The covalent bonds between the thiolated oligonucleotides with As atoms on the GaAs surface were investigated using x-ray photoelectron spectroscopy (XPS), and the surface morphology was obtained using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). In addition, I studied the effect of DNA length and the presence of a good solvent, such as water, on the oligonucleotides on a GaAs surface. I also investigated the effects of the thiol-based spacer and electrolyte concentration to improve the brush-like structure of the DNA layer. Finally, irradiation effects and AlGaAs resonators have been studied for the applications of DNA brush layer on GaAs as biosensor during the change of attachment probe DNA and hybridization to target DNA. For the 8-base thiolated ssDNA case, AFM results showed that the layer thickness was about ~2.2 nm in dry mode and increased in wet mode. Replacement reaction from N- , O- As bonds to S-As bonds was observed with addition of MCH as indicated by analysis of XPS spectra. The concentration of electrolyte affected the brush like layer structure. In the case of the longer, more flexible DNA with 100 bases, the DNA molecules strongly interacted with each other and formed big cluster, of 330~440nm in diameter on the surface. Finally, for the applications, a high level of radiation destroyed the brush layer. An AlGaAs resonator used as proof of concept a change in mass by a change in resonance frequency under hybridization reaction with complementary target DNA. This result shows that the design is viable and has a defection of ~25pg

Efficient Algorithms for Exact Graph Matching on Correlated Stochastic Block Models with Constant Correlation

We consider the problem of graph matching, or learning vertex correspondence, between two correlated stochastic block models (SBMs). The graph matching problem arises in various fields, including computer vision, natural language processing and bioinformatics, and in particular, matching graphs with inherent community structure has significance related to de-anonymization of correlated social networks. Compared to the correlated Erdos-Renyi (ER) model, where various efficient algorithms have been developed, among which a few algorithms have been proven to achieve the exact matching with constant edge correlation, no low-order polynomial algorithm has been known to achieve exact matching for the correlated SBMs with constant correlation. In this work, we propose an efficient algorithm for matching graphs with community structure, based on the comparison between partition trees rooted from each vertex, by extending the idea of Mao et al. (2021) to graphs with communities. The partition tree divides the large neighborhoods of each vertex into disjoint subsets using their edge statistics to different communities. Our algorithm is the first low-order polynomial-time algorithm achieving exact matching between two correlated SBMs with high probability in dense graphs.Comment: ICML 202

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Solid-State Electrochemical Protonation of SrCoO2.5 into HxSrCoO2.5 (x=1, 1.5, and 2)

Among many transition-metal oxides (TMOs), strontium cobalt oxide (SrCoOx) is a promising active material for advanced memory devices due to the versatile valence state of cobalt ions. Several SrCoOx-based electrochemical devices have been proposed, but solid-state protonation from SrCoO2.5 to HxSrCoO2.5 (x = 1, 1.5, and 2) at room temperature has not been demonstrated thus far due to the absence of an appropriate solid electrolyte. Here, we demonstrate a solid-state electrochemical protonation of SrCoO2.5 using mesoporous amorphous 12CaO center dot 7Al(2)O(3) (CAN) film as the solid electrolyte. The crystalline phase discretely changed from SrCoO2.5 to HSrCoO2.5 (phase A), H1.5SrCoO2.5 (phase B), and H2SrCoO2.5 (phase C) through formation of an intermediate phase of H1.25SrCoO2.5. H1.5SrCoO2.5 (phase B) was colorless transparent and showed weak ferromagnetism. The present results indicate that the CAN film can be used as the solid electrolyte for the protonation treatment of TMOs

Measuring user similarity using electric circuit analysis: application to collaborative filtering.

We propose a new technique of measuring user similarity in collaborative filtering using electric circuit analysis. Electric circuit analysis is used to measure the potential differences between nodes on an electric circuit. In this paper, by applying this method to transaction networks comprising users and items, i.e., user-item matrix, and by using the full information about the relationship structure of users in the perspective of item adoption, we overcome the limitations of one-to-one similarity calculation approach, such as the Pearson correlation, Tanimoto coefficient, and Hamming distance, in collaborative filtering. We found that electric circuit analysis can be successfully incorporated into recommender systems and has the potential to significantly enhance predictability, especially when combined with user-based collaborative filtering. We also propose four types of hybrid algorithms that combine the Pearson correlation method and electric circuit analysis. One of the algorithms exceeds the performance of the traditional collaborative filtering by 37.5% at most. This work opens new opportunities for interdisciplinary research between physics and computer science and the development of new recommendation systems

Unusually Large Thermopower Change from +330 to -185 mu V K-1 of Brownmillerite SrCoO2.5

Strontium cobalt oxide (SrCoO2.5) has recently attracted increasing attention as its optoelectronic and magnetic properties can be widely controlled using electrochemical oxidation/protonation at room temperature in air. To utilize the versatile properties of SrCoO2.5, it is essential to evaluate the location of the Fermi energy (E-F) in the electronic structure, which is sensitive to the oxidation state of the Co ions. Here, we show that thermopower is an excellent measure for analyzing the E-F in SrCoO2.5 epitaxial films. The lattice mismatch causes grain size reduction, which induces a slight increase in the oxidation state of the Co ions due to additional adsorbed oxygen. Although X-ray spectroscopy analyses reveal that the difference of the oxidation state of the Co ions among the samples is small, an unusually large change in thermopower from +330 mu V K-1 (lattice-matched) to -185 mu V K-1 (lattice-mismatched) is observed in the samples due to shifts in the E-F to the lower energy side. The present results demonstrate the excellent sensitivity of thermopower measurements for analyzing the location of E-F in the electronic structure of SrCoO(2.3 )in a practically usable environment