Latching dynamics in Potts neural networks

One purpose of Computational Neuroscience is to try to understand by using models how at least some parts in the brain work or how cognitive phenomena occur and are organized in terms of neuronal activity. The Hopfield model of a neural network, rooted in Statistical Physics, put forward by J. Hopfield in the 1980s, was one of the first attempts to explain how associative memory could work. It was successful in guiding experiments, e.g., in the hippocampus and primate inferotemporal cortex. However, some higher level cognitive functions that the brain accomplishes require, to be approached quantitaively, by more advanced models beyond simple cued retrieval..

Reducing a cortical network to a Potts model yields storage capacity estimates

An autoassociative network of Potts units, coupled via tensor connections, has been proposed and analysed as an effective model of an extensive cortical network with distinct short- and long-range synaptic connections, but it has not been clarified in what sense it can be regarded as an effective model. We draw here the correspondence between the two, which indicates the need to introduce a local feedback term in the reduced model, i.e., in the Potts network. An effective model allows the study of phase transitions. As an example, we study the storage capacity of the Potts network with this additional term, the local feedback w, which contributes to drive the activity of the network towards one of the stored patterns. The storage capacity calculation, performed using replica tools, is limited to fully connected networks, for which a Hamiltonian can be defined. To extend the results to the case of intermediate partial connectivity, we also derive the self-consistent signal-to-noise analysis for the Potts network; and finally we discuss implications for semantic memory in humans

Impact of Neuroimaging Patterns for the Detection of Atrial Fibrillation by Implantable Loop Recorders in Patients With Embolic Stroke of Undetermined Source

ObjectivesAtrial fibrillation (AF) is a well-known etiology of embolic stroke of undetermined source (ESUS), although the optimal detection strategy of AF was not been fully evaluated yet. We assessed AF detection rate by implantable loop recorder (ILR) in patients with ESUS and compared the clinical characteristics and neuroimaging patterns between the patients with AF and AF-free patients.MethodsWe reviewed clinical characteristics and neuroimaging patterns of consecutive patients with who were admitted to our comprehensive stroke center for ESUS and underwent ILR insertion between August 1, 2019, and January 31, 202. The inclusion criteria were (1) 18 years of age or older; (2) classified as having cryptogenic stroke extracted from the group with undetermined stroke according to ESUS International Working Group; and (3) underwent ILR insertion during or after admission due to index ischemic events. Ischemic stroke pattern was classified as (1) tiny-scattered infarction, (2) whole-territorial infarction, (3) lobar infarction and (4) multiple-territorial infarction. Interrogations of data retrieved from the ILR were performed by cardiologists in every month after the implantation.ResultsIn this study, 41 ESUS patients who received an ILR implantation were enrolled (mean age, 64 years; male sex, 65.9%). The rate of AF detection at 6 months was 34% (14 patients), and the mean time from ILR insertion to AF detection was 52.5 days [interquartile range (IQR), 45.0–69.5]. The median initial NIH stroke scale scores were significantly greater in patients with AF than those without AF (6.5 vs. 3.0, p = 0.019). Whole-territorial infarction pattern was significantly more frequent in patients with AF than in those without AF (64.3% vs.11.1%, p = 0.002).ConclusionsHigher covert AF detection rates within the ESUS patients were most often associated with higher NIHSS and whole-territorial infarction patterns on brain imaging

Local Corrosion of the Oxide Passivation Layer during Cu Chemical Mechanical Polishing

In this article, we analyze the effect of complexing agents in Cu chemical mechanical polishing slurry on the formation of oxide and the evolution of stress. The passivation property and surface morphology of the oxide on the surface showed significant differences depending on the kind of complexing agent. Oxalic acid showed fast oxide formation with poor passivation performance, and this caused large tensile stress evolution over 250 MPa in the Cu film. The synergetic effect of stress evolution and temperature increase due to the friction during the polishing caused severe pitting of the Cu surface after polishing in oxalic-acidbased slurry.This work was supported by the Korea Science and Engineering Foundation through the Research Center for Energy Conversion and Storage, the Fundamental Research and Development Program for Core Technology of Materials funded by the Korean Ministry of Commerce, Industry, and Energy, and by the Institute of Chemical Processes at Seoul National University

Outcomes of Pregnancy in Women with Congenital Heart Disease: A Single Center Experience in Korea

Pregnancy outcomes in patients with congenital heart disease have not been fully assessed in Korea. Forty-nine pregnancies that occurred in 34 women with congenital heart disease who registered at our hospital between September 1995 and April 2006 were reviewed. Spontaneous abortions occurred in two pregnancies at 6+1 and 7 weeks, and another two underwent elective pregnancy termination. One maternal death in puerperium occurred in a woman with Eisenmenger syndrome. Maternal cardiac complications were noted in 18.4%, pulmonary edema in 16.3%, symptomatic arrhythmia in 6.1%, deterioration of New York Heart Association (NYHA) functional class by ≥2 in 2.0%, and cardiac death in 2.0%. Independent predictors of adverse maternal cardiac events were an NYHA functional class of ≥3 (odds ratio [OR], 20.3), right ventricular dilation (OR, 21.2), and pulmonary hypertension (OR, 21.8). Neonatal complications occurred in 22.4% of pregnancies and included preterm delivery (16.3%), small for gestational age (12.2%), and neonatal death (2.0%). Independent predictors of adverse neonatal events were pulmonary hypertension (OR, 6.8) and NYHA functional class ≥3 (OR, 23.0). Pregnancy in women with congenital heart disease was found to be significantly associated with maternal cardiac and neonatal complications. Pre-pregnancy counseling and multidisciplinary care involving cardiologists and obstetricians are recommended for women with congenital heart disease contemplating pregnancy

Electroless Gold Plating on Aluminum Patterned Chips for CMOS-based Sensor Applications

We presented an approach for the activation of aluminum Al alloy using palladium Pd and the subsequent gold Au electroless plating ELP for complementary metal oxide semiconductor CMOS -based sensor applications. In this study, CMOS process compatible Al patterned chips were used as substrates for easy incorporation with existing CMOS circuits. To improve the contact resistance that arose from the Schottky barrier between the metal electrodes and the single-walled carbon nanotubes SWCNTs , electroless deposition of gold that has a higher work function than Al was adopted because the SWCNTs has p-type semiconductor properties. Each step of the Au ELP procedure was studied under various bath temperatures, immersion times, and chemical concentrations. Fine Pd particles were homogeneously distributed on the Al surface by the Pd activation process at room temperature. Au ELP allowed selective deposition of the Au film on the activated Al surface only. The SWCNT networks formed on the Au plated chip by a dip-coating method showed improved contact resistance and resistance variation between the Au electrode and SWCNTs. We also tried SWCNT decoration with the Au particle using the upper Au ELP method, which was expected to be applied in various areas including field-effect transistors and sensor devices.This work was supported by the Nano Systems Institute-National Core Research Center NSI-NCRC program of NRF and the TDPAF, Ministry for Agriculture, Forestry and Fisheries, Republic of Korea

Hemo-metabolic impairment in patients with ST-segment elevation myocardial infarction: Data from the INTERSTELLAR registry

Background: Not only hemo-dynamic (HD) factors but also hemo-metabolic (HM) risk factors reflecting multi-organ injuries are considered as important prognostic factors in ST-segment elevation myocardial infarction (STEMI). However, studies regarding HM risk factors in STEMI patients are currently limited. Method: Under analysis were 1,524 patients with STEMI who underwent primary percutaneous coronary intervention in the INTERSTELLAR registry. Patients were divided into HM (≥ 2 risk factors) and non-HM impairment groups. The primary outcome was in-hospital all-cause mortality, and the secondary outcome was 1-year all-cause mortality. Results: Of 1,524 patients, 214 (14.0%) and 1,310 (86.0%) patients were in the HM and non-HM impairment groups, respectively. Patients with HM impairment had a higher incidence of in-hospital mortality than those without (24.3% vs. 2.7%, p < 0.001). After adjusting for confounders, HM impairment was independently associated with in-hospital mortality (inverse probability of treatment weighting [IPTW]-adjusted odds ratio: 1.81, 95% confidence interval: 1.08–3.14). In the third door-to-balloon (DTB) time tertile (≥ 82 min), HM impairment was strongly associated with in-hospital mortality. In the first DTB time tertile ( < 62 min), indicating relatively rapid revascularization, HM impairment was consistently associated with increased in-hospital mortality. Conclusions: Hemo-metabolic impairment is significantly associated with increased risk of in-hospital and 1-year mortality in patients with STEMI. It remains a significant prognostic factor, regardless of DTB time

Effect of pre-stroke statin use on stroke severity and early functional recovery: a retrospective cohort study

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.Abstract Background Experimental studies suggest that pre-stroke statin treatment has a dual effect of neuroprotection during ischemia and neurorestoration after ischemic injury. The aim of this study was to evaluate the effect of pre-stroke statin use on initial stroke severity and early clinical outcome. Methods We used a prospective database enrolling patients with acute ischemic stroke from 12 hospitals in Korea between April 2008 and January 2012. Primary endpoint was the initial stroke severity as measured by the National Institutes of Health Stroke Scale (NIHSS) score. Secondary endpoints were good outcome (modified Rankin Scale [mRS], 0–2) and overall mRS distribution at discharge. Multivariable regression model and propensity score (PS) matching were used for statistical analyses. Results Among the 8340 patients included in this study, 964 patients (11.6 %) were pre-stroke statin users. The initial NIHSS score (mean [95 % CI]) was lower among pre-stroke statin users vs. non-users in multivariable analysis (5.7 [5.2–6.3] versus 6.4 [5.9–6.9], p = 0.002) and PS analysis (5.2 [4.7–5.7] versus 5.7 [5.4–6.0], p = 0.043). Pre-stroke statin use was associated with increased achievement of mRS 0–2 outcome (multivariable analysis: OR [95 % CI], 1.55 [1.25–1.92], p < 0.001; PS matching: OR [95 % CI], 1.47 [1.16-1.88]; p = 0.002) and favorable shift on the overall mRS distribution (multivariable analysis: OR [95 % CI], 1.29 [1.12-1.51], p = 0.001; PS matching: OR [95 % CI], 1.31 [1.11-1.54]; p = 0.001). Conclusions Pre-stroke statin use was independently associated with lesser stroke severity at presentation and better early functional recovery in patients with acute ischemic stroke

Upgrading and upstaging of low-risk prostate cancer among Korean patients: a multicenter study

Only 54% of prostate cancer cases in Korea are localized compared with 82% of cases in the US. Furthermore, half of Korean patients are upgraded after radical prostatectomy (41.6%-50.6%). We investigated the risk factors for upgrading and/or upstaging of low-risk prostate cancer after radical prostatectomy. We retrospectively reviewed the medical records of 1159 patients who underwent radical prostatectomy at five hospitals in Honam Province. Preoperative data on standard clinicopathological parameters were collected. The radical prostatectomy specimens were graded and staged and we defined a "worsening prognosis" as a Gleason score ≥ 7 or upstaging to ≥ pT3. Multivariate logistic regression models were used to assess factors associated with postoperative pathological upstaging. Among the 1159 patients, 324 were classified into the clinically low-risk group, and 154 (47.5%) patients were either upgraded or upstaged. The multivariable analysis revealed that the preoperative serum prostate-specific antigen level (odds ratio [OR], 1.131; 95% confidence interval [CI], 1.007-1.271; P= 0.037), percent positive biopsy core (OR: 1.018; 95% CI: 1.002-1.035; P= 0.032), and small prostate volume (≤30 ml) (OR: 2.280; 95% CI: 1.351-3.848; P= 0.002) were predictive of a worsening prognosis. Overall, 47.5% of patients with low-risk disease were upstaged postoperatively. The current risk stratification criteria may be too relaxed for our study cohort