Classification of time series by shapelet transformation

Time-series classification (TSC) problems present a specific challenge for classification algorithms: how to measure similarity between series. A \emph{shapelet} is a time-series subsequence that allows for TSC based on local, phase-independent similarity in shape. Shapelet-based classification uses the similarity between a shapelet and a series as a discriminatory feature. One benefit of the shapelet approach is that shapelets are comprehensible, and can offer insight into the problem domain. The original shapelet-based classifier embeds the shapelet-discovery algorithm in a decision tree, and uses information gain to assess the quality of candidates, finding a new shapelet at each node of the tree through an enumerative search. Subsequent research has focused mainly on techniques to speed up the search. We examine how best to use the shapelet primitive to construct classifiers. We propose a single-scan shapelet algorithm that finds the best $k$ shapelets, which are used to produce a transformed dataset, where each of the $k$ features represent the distance between a time series and a shapelet. The primary advantages over the embedded approach are that the transformed data can be used in conjunction with any classifier, and that there is no recursive search for shapelets. We demonstrate that the transformed data, in conjunction with more complex classifiers, gives greater accuracy than the embedded shapelet tree. We also evaluate three similarity measures that produce equivalent results to information gain in less time. Finally, we show that by conducting post-transform clustering of shapelets, we can enhance the interpretability of the transformed data. We conduct our experiments on 29 datasets: 17 from the UCR repository, and 12 we provide ourselve

Opening of small and intermediate calcium-activated potassium channels induce relaxation mainly mediated by NO release in large arteries and EDHF in small arteries from rat Number of text pages: 22 Number of tables: 0 Number of figures: 5 Number of refere

Abstract This study was designed to investigate whether calcium-activated potassium channels of small (SK Ca or K Ca 2) and intermediate (IK Ca or K Ca 3.1) conductance activated by NS309 are involved in both nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) type relaxation in large and small rat mesenteric arteries. Segments of rat superior and small mesenteric arteries were mounted in myographs for functional studies. NO was recorded using NO microsensors. SK Ca and IK Ca channel-currents, and mRNA expression were investigated in human umbilical vein endothelial cells (HUVECs), and calcium concentrations both in HUVEC and mesenteric arterial endothelial cells. In both superior (~1093 µm) and small mesenteric (~300 µm) arteries, NS309, evoked endothelium-and concentration-dependent relaxations. In superior mesenteric arteries, NS309 relaxations and NO release were inhibited both by asymmetric dimethylarginine (ADMA, 300 µM), an inhibitor of NO synthase, and by apamin (0.5 µM) plus TRAM 34 (1 µM), blockers of SK Ca and IK Ca channels, respectively. In small mesenteric arteries, NS309 relaxations were slightly reduced by ADMA, whereas apamin plus an IK Ca channel blocker almost abolished the relaxation. Iberiotoxin did not change NS309 relaxation. HUVECs expressed mRNA for SK Ca and IK Ca channels, and NS309 induced increases in calcium, outward current, and NO release that was blocked by apamin and TRAM 34 or charybdotoxin. These findings suggest that opening of SK Ca and IK Ca channels leads to endothelium-dependent relaxation that is mainly mediated by NO in large mesenteric arteries and by EDHF-type relaxation in small mesenteric arteries. NS309-induced calcium influx appears to contribute to formation of NO. JPET #179242

Global treatment of haemorrhoids-A worldwide snapshot audit conducted by the International Society of University Colon and Rectal Surgeons

AimThere is no universally accepted treatment consensus for haemorrhoids, and thus, management has been individualized all over the world. This study was conducted to assess a global view of how surgeons manage haemorrhoids.MethodsThe research panel of the International Society of University Colon and Rectal Surgeons (ISUCRS) developed a voluntary, anonymous questionnaire evaluating surgeons' experience, volume and treatment approaches to haemorrhoids. The 44 multiple-choice questionnaire was available for one month via the ISUCRS email database and the social media platforms Viber and WhatsApp.ResultsThe survey was completed by 1005 surgeons from 103 countries; 931 (92.6%) were in active practice, 819 (81.5%) were between 30 and 60 years of age, and 822 (81.8%) were male. Detailed patient history (92.9%), perineal inspection (91.2%), and digital rectal examination (91.1%) were the most common assessment methods. For internal haemorrhoids, 924 (91.9%) of participants graded them I-IV, with the degree of haemorrhoids being the most important factor considered to determine the treatment approach (76.3%). The most common nonprocedural/conservative treatment consisted of increased daily fibre intake (86.9%), increased water intake (82.7%), and normalization of bowel habits/toilet training (74.4%). Conservative treatment was the first-line treatment for symptomatic first (92.5%), second (72.4%) and third (47.3%) degree haemorrhoids; however, surgery was the first-line treatment for symptomatic fourth degree haemorrhoids (77.6%). Rubber band ligation was the second-line treatment in first (50.7%) and second (47.2%) degree haemorrhoids, whereas surgery was the second-line treatment in third (82.9%) and fourth (16.7%) degree symptomatic haemorrhoids. Rubber band ligation was performed in the office by 645(64.2%) of the participants. The most common surgical procedure performed for haemorrhoids was an excisional haemorrhoidectomy for both internal (87.1%) and external (89.7%) haemorrhoids - with 716 (71.2%) of participants removing 1, 2 or 3 sectors as necessary.ConclusionAlthough there is no global haemorrhoidal treatment consensus, there are many practice similarities among the different cultures, resources, volume and experience of surgeons around the world. With additional studies, a consensus statement could potentially be developed

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research