K-theoretic Aspects of String Theory Dualities

String theory is a a physical field theory in which point particles are replaced by 1-manifolds propagating in time, called strings. The 2-manifold representing the time evolution of a string is called the string worldsheet. Strings can be either closed (meaning their worldsheets are closed surfaces) or open (meaning their worldsheets have boundary). A D-brane is a submanifold of the spacetime manifold on which string endpoints are constrained to lie. There are five different string theories that have supersymmetry, and they are all related by various dualities. This dissertation will review how D-branes are classified by K-theory. We will then explore the $K$-theoretic aspects of a hypothesized duality between the type I theory compactified on a 4-torus and the type IIA theory compactified on a K3 surface, by looking at a certain blow down of the singular limit of K3. This dissertation concludes by classifying D-branes on the type II orientifold T4/Z2 when the Z2 action is multiplication by -1 and the H-flux is trivial. We find that classifying D-branes on the singular limit of K3, T4/Z2 by equivariant K-theory agrees with the classification of D-branes on a smooth K3 surface by ordinary K-theory

The minimal important difference of the hospital anxiety and depression scale in patients with chronic obstructive pulmonary disease

BACKGROUND: Interpretation of the Hospital Anxiety and Depression Scale (HADS), commonly used to assess anxiety and depression in COPD patients, is unclear. Since its minimal important difference has never been established, our aim was to determine it using several approaches. METHODS: 88 COPD patients with FEV1 /= 0.5 we performed linear regression analyses to predict the minimal important difference from the anchors. As distribution-based approach we used the Effect Size approach. RESULTS: Based on CRQ emotional function and mastery domain as well as on total scores, the minimal important difference was 1.41 (95% CI 1.18-1.63) and 1.57 (1.37-1.76) for the HADS anxiety score and 1.68 (1.48-1.87) and 1.60 (1.38-1.82) for the HADS total score. Correlations of the HADS depression score and CRQ domain and Feeling Thermometer scores were < 0.5. Based on the Effect Size approach the MID of the HADS anxiety and depression score was 1.32 and 1.40, respectively. CONCLUSION: The minimal important difference of the HADS is around 1.5 in COPD patients corresponding to a change from baseline of around 20%. It can be used for the planning and interpretation of trials

Mapping the landscape of lung cancer breath analysis: A scoping review (ELCABA)

Lung cancer is the leading cause of cancer death worldwide due to its late-stage detection. Lung cancer screening, including low-dose computed tomography (low-dose CT), provides an initial clinical solution. Nevertheless, further innovations and refinements would help to alleviate remaining limitations. The non-invasive, gentle, and fast nature of breath analysis (BA) makes this technology highly attractive to supplement low-dose CT for an improved screening algorithm. However, BA has not taken hold in everyday clinical practice. One reason might be the heterogeneity and variety of BA methods. This scoping review is a comprehensive summary of study designs, breath analytical methods, and suggested biomarkers in lung cancer. Furthermore, this synthesis provides a framework with core outcomes for future studies in lung cancer BA. This work supports future research for evidence synthesis, meta-analysis, and translation into clinical routine workflows. Keywords: Biomarker; Breath; Detection; Lung cancer; Scoping review; Screenin

Extended lymph node resection versus standard resection for pancreatic and periampullary adenocarcinoma

BACKGROUND Pancreatic and periampullary adenocarcinomas account for some of the most aggressive malignancies, and the leading causes of cancer-related mortalities. Partial pancreaticoduodenectomy (PD) with negative resection margins is the only potentially curative therapy. The high prevalence of lymph node metastases has led to the hypothesis that wider excision with the removal of more lymphatic tissue could result in an improvement of survival, and higher rates of negative resection margins. OBJECTIVES To compare overall survival following standard (SLA) versus extended lymph lymphadenectomy (ELA) for pancreatic head and periampullary adenocarcinoma. We also compared secondary outcomes, such as morbidity, mortality, and tumour involvement of the resection margins between the two procedures. SEARCH METHODS We searched CENTRAL, MEDLINE, PubMed, and Embase from 1973 to September 2020; we applied no language restrictions. SELECTION CRITERIA Randomised controlled trials (RCT) comparing PD with SLA versus PD with ELA, including participants with pancreatic head and periampullary adenocarcinoma. DATA COLLECTION AND ANALYSIS Two review authors independently screened references and extracted data from study reports. We calculated pooled risk ratios (RR) for most binary outcomes except for postoperative mortality, for which we estimated a Peto odds ratio (Peto OR), and mean differences (MD) for continuous outcomes. We used a fixed-effect model in the absence of substantial heterogeneity (I² 25%). Two review authors independently assessed risk of bias, and we used GRADE to assess the quality of the evidence for important outcomes. MAIN RESULTS We included seven studies with 843 participants (421 ELA and 422 SLA). All seven studies included Kaplan-Meier curves for overall survival. There was little or no difference in survival between groups (log hazard ratio (log HR) 0.12, 95% confidence interval (CI) -3.06 to 3.31; P = 0.94; seven studies, 843 participants; very low-quality evidence). There was little or no difference in postoperative mortality between the groups (Peto odds ratio (OR) 1.20, 95% CI 0.51 to 2.80; seven studies, 843 participants; low-quality evidence). Operating time was probably longer for ELA (mean difference (MD) 50.13 minutes, 95% CI 19.19 to 81.06 minutes; five studies, 670 participants; moderate-quality evidence). There was substantial heterogeneity between the studies (I² = 88%; P < 0.00001). There may have been more blood loss during ELA (MD 137.43 mL, 95% CI 11.55 to 263.30 mL; two studies, 463 participants; very low-quality evidence). There was substantial heterogeneity between the studies (I² = 81%, P = 0.02). There may have been more lymph nodes retrieved during ELA (MD 11.09 nodes, 95% CI 7.16 to 15.02; five studies, 670 participants; moderate-quality evidence). There was substantial heterogeneity between the studies (I² = 81%, P < 0.00001). There was little or no difference in the incidence of positive resection margins between groups (RR 0.81, 95% CI 0.58 to 1.13; six studies, 783 participants; very low-quality evidence). AUTHORS' CONCLUSIONS There is no evidence of an impact on survival with extended versus standard lymph node resection. However, the operating time may have been longer and blood loss greater in the extended resection group. In conclusion, current evidence neither supports nor refutes the effect of extended lymph lymphadenectomy in people with adenocarcinoma of the head of the pancreas

Discovering universal statistical laws of complex networks

Different network models have been suggested for the topology underlying complex interactions in natural systems. These models are aimed at replicating specific statistical features encountered in real-world networks. However, it is rarely considered to which degree the results obtained for one particular network class can be extrapolated to real-world networks. We address this issue by comparing different classical and more recently developed network models with respect to their generalisation power, which we identify with large structural variability and absence of constraints imposed by the construction scheme. After having identified the most variable networks, we address the issue of which constraints are common to all network classes and are thus suitable candidates for being generic statistical laws of complex networks. In fact, we find that generic, not model-related dependencies between different network characteristics do exist. This allows, for instance, to infer global features from local ones using regression models trained on networks with high generalisation power. Our results confirm and extend previous findings regarding the synchronisation properties of neural networks. Our method seems especially relevant for large networks, which are difficult to map completely, like the neural networks in the brain. The structure of such large networks cannot be fully sampled with the present technology. Our approach provides a method to estimate global properties of under-sampled networks with good approximation. Finally, we demonstrate on three different data sets (C. elegans' neuronal network, R. prowazekii's metabolic network, and a network of synonyms extracted from Roget's Thesaurus) that real-world networks have statistical relations compatible with those obtained using regression models

Measuring social dynamics in a massive multiplayer online game

Quantification of human group-behavior has so far defied an empirical, falsifiable approach. This is due to tremendous difficulties in data acquisition of social systems. Massive multiplayer online games (MMOG) provide a fascinating new way of observing hundreds of thousands of simultaneously socially interacting individuals engaged in virtual economic activities. We have compiled a data set consisting of practically all actions of all players over a period of three years from a MMOG played by 300,000 people. This large-scale data set of a socio-economic unit contains all social and economic data from a single and coherent source. Players have to generate a virtual income through economic activities to `survive' and are typically engaged in a multitude of social activities offered within the game. Our analysis of high-frequency log files focuses on three types of social networks, and tests a series of social-dynamics hypotheses. In particular we study the structure and dynamics of friend-, enemy- and communication networks. We find striking differences in topological structure between positive (friend) and negative (enemy) tie networks. All networks confirm the recently observed phenomenon of network densification. We propose two approximate social laws in communication networks, the first expressing betweenness centrality as the inverse square of the overlap, the second relating communication strength to the cube of the overlap. These empirical laws provide strong quantitative evidence for the Weak ties hypothesis of Granovetter. Further, the analysis of triad significance profiles validates well-established assertions from social balance theory. We find overrepresentation (underrepresentation) of complete (incomplete) triads in networks of positive ties, and vice versa for networks of negative ties...Comment: 23 pages 19 figure

Novel Prediction Score Including Pre- and Intraoperative Parameters Best Predicts Acute Kidney Injury after Liver Surgery

Background: A recently published score predicts the occurrence of acute kidney injury (AKI) after liver resection based on preoperative parameters (chronic renal failure, cardiovascular disease, diabetes, and alanine-aminotransferase levels). By inclusion of additional intraoperative parameters we aimed to develop a new prediction model. Methods: A series of 549 consecutive patients were enrolled. The preoperative score and intraoperative parameters (blood transfusion, hepaticojejunostomy, oliguria, cirrhosis, diuretics, colloids, and catecholamine) were included in a multivariate logistic regression model. We added the strongest predictors that improved prediction of AKI compared to the existing score. An internal validation by fivefold cross validation was performed, followed by a decision curve analysis to evaluate unnecessary special care unit admissions. Results: Blood transfusions, hepaticojejunostomy, and oliguria were the strongest intraoperative predictors of AKI after liver resection. The new score ranges from 0 to 64 points predicting postoperative AKI with a probability of 3.5-95%. Calibration was good in both models (15% predicted risk vs. 15% observed risk). The fivefold cross-validation indicated good accuracy of the new model (AUC 0.79 (95% CI 0.73-0.84)). Discrimination was substantially higher in the new model (AUCnew 0.81 (95% CI 0.76-0.86) versus AUCpreoperative 0.60 (95% CI 0.52-0.69), p<0.001). The new score could reduce up to 84 unnecessary special care unit admissions per 100 patients depending on the decision threshold. Conclusions: By combining three intraoperative parameters with the existing preoperative risk score, a new prediction model was developed that more accurately predicts postoperative AKI. It may reduce unnecessary admissions to the special care unit and support management of patients at higher ris

Impact of Preoperative Bevacizumab on Complications After Resection of Colorectal Liver Metastases: Case-Matched Control Study

Background: Chemotherapy may increase postoperative morbidity and mortality after liver surgery. Especially bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), could have a detrimental effect. To assess the impact of neoadjuvant bevacizumab on clinical outcome after hepatectomy for colorectal liver metastases (CRLMs) this case-matched control study was initiated. Methods: The multicentric data collection was performed in the Swiss HPB Center of the University Hospital Zurich (CH), the Department of Digestive Surgery and Transplantation Strasbourg (F), and the Division of Hepato-biliary-pancreatic surgery of "Josep Tureta” Hospital Girona (E). Consecutive patients operated onbetween July 2005 and December 2007 due to CRLMs who received neoadjuvant chemotherapy were assessed. Patients were divided in two groups: group A had neoadjuvant chemotherapy with bevacicumab, and group B had it without bevacizumab. Results: No differences in overall morbidity (56 vs. 40% in the bevacizumab and control groups, respectively, p=0.23) or mortality could be documented. Similarly, the incidence of severe postoperative complications was not statistically different between the bevacizumab and control groups (31 and 18%, respectively, p=0.31). Wound complications were comparable (11% in the bevacizumab group compared and 9% in the control group, p=1.00). However, bevacizumab was associated with a significantly decreased incidence of postoperative hepatic insufficiency (7 vs. 20%, p=0.03). Conclusions: No impact on the incidence or severity of complications by bevacizumab could be shown. Bevacizumab may even reduce the incidence of liver failure after liver surger

Lány – ein Produktionsort gegossenener Bronzen der Spätawarenzeit in der awarisch-slawischen Kontaktzone des unteren Thayatals

Interdisciplinary research, carried out by the Masaryk University Brno and the University of Vienna, at the site of Lány (CZ) at the border between Austria and Moravia has revealed a large settlement (∼12ha) from the 6th century until the 8th/9th century in a contact zone between Slavonic and Avarian influences. Aside from pottery that ranges from early slavic finds of the Prague type to specimens of the middle-danubian tradition („mitteldanubische Kulturtradition“) and other finds such as spindle whorls etc. several dozen typical Avar belt accessories have been found. Most of them date to the late Avar III period, are brand new and do not show any traces of usage. Together with semi-finished products, miscast objects and remains of the bronze casting process, we interpret Lány as a production site/ workshop for Avar belts. L any is at the very Northwestern periphery of the Avar Khaganate. However, material culture, aside from the belt accessories, is much more associated with what we know from regions where Slavonic populations of the 7th/8th century had settled. We furthermore discuss the usage of Avar belts amongst the Slavic elites of the 8th century and possible explanations for the dense distribution of Avar finds outside of the Khaganate

Absence of Type I Interferon Autoantibodies or Significant Interferon Signature Alterations in Adults With Post-COVID-19 Syndrome

Genetic defects in the interferon (IFN) system or neutralizing autoantibodies against type I IFNs contribute to severe COVID-19. Such autoantibodies were proposed to affect post-COVID-19 syndrome (PCS), possibly causing persistent fatigue for >12 weeks after confirmed SARS-CoV-2 infection. In the current study, we investigated 128 patients with PCS, 21 survivors of severe COVID-19, and 38 individuals who were asymptomatic. We checked for autoantibodies against IFN-α, IFN-β, and IFN-ω. Few patients with PCS had autoantibodies against IFNs but with no neutralizing activity, indicating a limited role of type I IFNs in PCS pathogenesis. In a subset consisting of 28 patients with PCS, we evaluated IFN-stimulated gene activity and showed that it did not correlate with fatigue. In conclusion, impairment of the type I IFN system is unlikely responsible for adult PCS