On Krebes' tangle

A genus-1 tangle G is an arc properly embedded in a standardly embedded solid torus S in the 3-sphere. We say that a genus-1 tangle embeds in a knot K in S^3 if the tangle can be completed by adding an arc exterior to the solid torus to form the knot K. We call K a closure of G. An obstruction to embedding a genus-1 tangle G in a knot is given by torsion in the homology of branched covers of S branched over G. We examine a particular example A of a genus-1 tangle, given by Krebes, and consider its two double-branched covers. Using this homological obstruction, we show that any closure of A obtained via an arc which passes through the hole of S an odd number of times must have determinant divisible by three. A resulting corollary is that if A embeds in the unknot, then the arc which completes A to the unknot must pass through the hole of S an even number of times.Comment: 7 pages, 7 figures. v2: Minor changes made, typos corrected. v3: Final version, accepted for publicatio

Units of the String Link Monoids

We show that the map obtained by viewing a geometric (ie. representative) braid as a string link induces an isomorphism of the n-strand braid group onto the group of units of the n-strand string link monoid.Comment: 9 pages, 5 figures. Accepted for publication in Knots in Poland III (Banach Center Publications

Flattening the Curve: The Role of Communications in Canada’s Response to COVID-19

This paper explores Canada’s communications approach to the population during the global pandemic of COVID-19. Canada’s perceptive risk communication plan consists of quick response, transparency, and credible figures as representatives of information that are deemed the current principles of success (as of April 2020). The literature review inaugurates the necessary definitions for the topic and provides detailed information about the action Canada has taken in the 2020 pandemic, while the discussion evaluates and debates Canada’s communicative strengths while acknowledging areas for improvement. Following the tactics explored, comparisons are made against the United States’ pandemic response along with a review of practices to avoid in risk communication, such as blame. Finally, transformative dialogue theory is analyzed as a potential answer to the successful interactions between the Canadian government, authoritative figures, and the public.&nbsp

Untersuchung zur Einhaltung der leitlinienkonformen Diagnostik und Therapie bei Patienten mit Candidämie und deren Einfluss auf die Mortalität

Hintergrund: Hefepilze der Gattung Candida sind die häufigste Ursache für Pilzinfektionen beim Menschen. Eine invasive Candida-Infektion ist mit einer Mortalität von 15-47% verbunden. 2009 veröffentlichte die Infectious Disease Society of America (IDSA) die Leitlinien zur Behandlung der Candidiasis, gefolgt von der European Society of Clinical Microbiology and Infectious Diseases (ESCMID) 2012 und anderen nationalen und internationalen Leitlinien. Ziel dieser Studie war es, die Einhaltungsrate ausgewählter, in den Leitlinien geforderter Maßnahmen zu ermitteln und den Einfluss der leitlinienkonformen Behandlung auf das Outcome zu untersuchen. Material / Methoden: Es wurde eine multizentrische, retrospektive, klinische Studie auf Intensivstationen in Berlin durchgeführt. Patienten mit Candida-positiven Blutkulturen wurden aus mikrobiologischen Datenbanken erhoben. Erwachsene mit einer Aufenthaltsdauer von über 48 Stunden auf Intensivstation, die zwischen 2009 und 2011 behandelt wurden, wurden eingeschlossen. Die Recherche der Patientendaten erfolgte aus medizinischen Papierkrankenakten sowie elektronischen Krankenhaus- und Laborunterlagen. Die Einhaltung der Leitlinien wurde anhand der Merkmale Wechsel zentraler Venenkatheter, Abnahme einer Folge-Blutkultur, Untersuchung des Augenhintergundes und Durchführung einer Echokardiografie sowie der Therapiedauer von 14 Tagen nach der ersten negativen Blutkultur betrachtet. Die kumulative Einhaltung der Leitlinien wurde mit ≥ 70% leitlinienkonformer Diagnostik und Therapie (gemessen mit ≥7 Punkten in einem eigens gewichteten Punktescore) festgelegt. Für die univariate Analyse wurde der Chi-Quadrat-Test und der Mann-Whitney-U-Test verwendet. Der Einfluss der Leitlinieneinhaltung auf die Mortalität wurde in multiplen logistischen Regressionen untersucht. Die Studie wurde von der institutionellen Ethikkommission genehmigt (EA4 / 113/11). Ergebnisse: 119 kritisch kranke Intensivpatienten wurden in die Studie eingeschlossen. Etwa zwei Drittel der Patienten erhielten einen Wechsel zentraler Venenkatheter (63%) und die Abnahme einer Folge-Blutkultur (72,3%). Bei 49,6% der Patienten erfolgte eine Echokardiografie, dreimal wurde eine Endokarditis diagnostiziert. 19 von 119 Patienten (16%) erhielten eine Untersuchung des Augenhintergrundes, eine Candida-Endophthalmitis wurde in keinem Fall bestätigt. Eine adäquate Therapiedauer erfolgte bei 51,7% der Patienten. Wir fanden mehr leitlinienkonforme Diagnostik und Therapie bei schwerer kranken Patienten. Bei etwa der Hälfte der Patienten (51,3%) wurden die Leitlinien kumulativ als eingehalten bewertet. Die Einhaltung der Leitlinien hatte keinen Überlebensvorteil für Patienten. Allein das Organversagen mittels SOFA-Score, hatte einen signifikanten Einfluss auf die Mortalität (p=0,001). Schlussfolgerungen: Für die Behandlung von Patienten mit Candidämie sollten interdisziplinäre Konzepte im Rahmen von Antimicrobial Stewardship Programmen an Kliniken implementiert werden. Bundle, Score-Systeme und Feedback können helfen Leitlinien ans Krankenbett zu bringen und die Einhaltung zu verbessern. Der Einfluss der Leitlinien auf die Mortalität muss in prospektiven Studien validiert werden.Candida species represent the most common cause of fungal infections in human. Invasive candida infection is associated with mortality risk of 15-47 %. In 2009 Infectious Disease Society of America (IDSA) issued the guidelines for treatment of candidiasis followed in 2012 by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and other national and international guidelines. The aim of this study was to determine the compliance rate of selected measures required in the guidelines and to investigate the association of guideline adherence on outcome. Material/methods: We conducted a multicentre retrospective clinical study on intensive care units in Berlin, Germany. Patients with blood culture-proven candidemia were collected from microbiological databases. Adults with length of stay over 48 hours treated between 2009 and 2011 were included. The corresponding clinical data were collected from paper-based medical charts and electronic hospital and laboratory records. Adherence to guidelines was assessed by removel of central line, taking follow-up of blood culture, ophthalmologic assessment, echocardiography and antimycotic therapy 14 days after the first negative blood culture. Cumulative guideline adherence was determined to be ≥ 70% guideline-compliant diagnosis and therapy (measured at ≥7 points in a self-weighted point score). We used Chi-square test and Mann-Whitney U-test for univariate analysis. The impact of guideline adherence on mortality was examined in multiple logistic regressions. The institutional Ethics Board approved this study (EA4/113/11). Results: 119 critically ill intensive care patients were included in the study. About two-thirds of patients received removel of central line (63%) and taking follow-up blood culture (72.3%). Echocardiography was performed in 49.6% of patients and endocarditis was diagnosed three times. 19 out of 119 patients (16%) underwent ophthalmologic assessment, no candida endophthalmitis was confirmed. Recommanded therapy was achieved in 51.7% of the patients. We found better guideline adherence in more seriously ill patients, cumulative adherence was found in about half of the patients (51.3%). Compliance with the guidelines had no survival benefit for patients. Organ failure alone using the SOFA score had a significant effect on mortality (p = 0.001). Conclusion: For the treatment of patients with candidemia, interdisciplinary concepts should be implemented in hospitals through antimicrobial stewardship programs. Bundle, score systems and feedback are helpful to bring guidelines to the bedside and to improve compliance. The influence of the guidelines on mortality must be validated in prospective studies

Emergency Stroke Calls: Obtaining Rapid Telephone Triage (ESCORTT) - a programme of research to facilitate recognition of stroke by emergency medical dispatchers

Background: Rapid access to emergency stroke care can reduce death and disability by enabling immediate provision of interventions such as thrombolysis, physiological monitoring and stabilisation. One of the ways that access to services can be facilitated is through emergency medical service (EMS)dispatchers. The sensitivity of EMS dispatchers for identifying stroke is < 50%. Studies have shown that activation of the EMSs is the single most important factor in the rapid triage and treatment of acute stroke patients. Objectives: To facilitate recognition of stroke by emergency medical dispatchers (EMDs). Design: An eight-phase mixed-methods study. Phase 1: a retrospective cohort study exploring stroke diagnosis. Phase 2: semi-structured interviews exploring public and EMS interactions. Phases 3 and 4: a content analysis of 999 calls exploring the interaction between the public and EMDs. Phases 5–7: development and implementation of stroke-specific online training (based on phases 1–4). Phase 8: an interrupted time series exploring the impact of the online training. Setting: One ambulance service and four hospitals. Participants: Patients arriving at hospital by ambulance with stroke suspected somewhere on the stroke pathway (phases 1 and 8). Patients arriving at hospital by ambulance with a final diagnosis of stroke (phase 2). Calls to the EMSs relating to phase 1 patients (phases 3 and 4). EMDs (phase 7). Interventions: Stroke-specific online training package, designed to improve recognition of stroke for EMDs. Main outcome measures: Phase 1: symptoms indicative of a final and dispatch diagnosis of stroke. Phase 2: factors involved in the decision to call the EMSs when stroke is suspected. Phases 3 and 4: keywords used by the public when describing stroke and non-stroke symptoms to EMDs. Phase 8: proportion of patients with a final diagnosis of stroke correctly dispatched as stroke by EMDs. Results: Phase 1: for patients with a final diagnosis of stroke, facial weakness and speech problems were significantly associated with an EMD code of stroke. Phase 2: four factors were identified – perceived seriousness; seeking and receiving lay or professional advice; caller’s description of symptoms and emotional response to symptoms. Phases 3 and 4: mention of ‘stroke’ or one or more Face Arm Speech Test (FAST) items is much more common in stroke compared with non-stroke calls. Consciousness level was often difficult for callers to determine and/or communicate. Phase 8: there was a significant difference (p = 0.003) in proportions correctly dispatched as stroke – before the training was implemented 58 out of 92 (63%); during implementation of training 42 out of 48 (88%); and after training implemented 47 out of 59 (80%). Conclusions: EMDs should be aware that callers are likely to describe loss of function (e.g. unable to grip) rather than symptoms (e.g. weakness) and that callers using the word ‘stroke’ or describing facial weakness, limb weakness or speech problems are likely to be calling about a stroke. Ambiguities and contradictions in dialogue about consciousness level arise during ambulance calls for suspected and confirmed stroke. The online training package improved recognition of stroke by EMDs. Recommendations for future research include testing the effectiveness of the Emergency Stroke Calls: Obtaining Rapid Telephone Triage (ESCORTT) training package on the recognition of stroke across other EMSs in England; and exploring the impact of the early identification of stroke by call handlers on patient and process outcomes. Funding: The National Institute for Health Research Programme Grants for Applied Research programme

Ablation of C-type natriuretic peptide/cGMP signaling in fibroblasts exacerbates adverse cardiac remodeling in mice

Excessive activation of cardiac fibroblasts (CFs) in response to injury provokes cardiac fibrosis, stiffness, and failure. The local mediators counter-regulating this response remain unclear. Exogenous C-type natriuretic peptide (CNP) exerted antifibrotic effects in preclinical models. To unravel the role of the endogenous hormone, we generated mice with fibroblast-restricted deletion (KO) of guanylyl cyclase-B (GC-B), the cGMP-synthesizing CNP receptor.CNP activated GC-B/cGMP signaling in human and murine CFs, preventing proliferative and promigratory effects of AngiotensinII (AngII) and TGF-β. Fibroblast-specific GC-B-KO mice showed enhanced fibrosis in response to AngII infusions. Moreover, after two weeks of mild pressure-overload induced by transverse aortic constriction (TAC), such KO mice had augmented cardiac fibrosis and hypertrophy, together with systolic and diastolic contractile dysfunction. This was associated with increased expression of the profibrotic genes collagen I, III and periostin. Notably, such responses to AngII and TAC were greater in female as compared to male KO mice. Enhanced AngII-induced CNP expression in female hearts and augmented GC-B expression and activity in female CFs may contribute to this sex disparity.The results show that paracrine CNP signaling in CFs has antifibrotic and antihypertrophic effects. The CNP/GC-B/cGMP pathway might be a target for therapies combating pathological cardiac remodeling

Diversity and distribution of genetic variation in gammarids: Comparing patterns between invasive and non-invasive species

© 2017 Published by John Wiley & Sons Ltd. Biological invasions are worldwide phenomena that have reached alarming levels among aquatic species. There are key challenges to understand the factors behind invasion propensity of non-native populations in invasion biology. Interestingly, interpretations cannot be expanded to higher taxonomic levels due to the fact that in the same genus, there are species that are notorious invaders and those that never spread outside their native range. Such variation in invasion propensity offers the possibility to explore, at fine-scale taxonomic level, the existence of specific characteristics that might predict the variability in invasion success. In this work, we explored this possibility from a molecular perspective. The objective was to provide a better understanding of the genetic diversity distribution in the native range of species that exhibit contrasting invasive propensities. For this purpose, we used a total of 784 sequences of the cytochrome c oxidase subunit I of mitochondrial DNA (mtDNA-COI) collected from seven Gammaroidea, a superfamily of Amphipoda that includes species that are both successful invaders (Gammarus tigrinus, Pontogammarus maeoticus, and Obesogammarus crassus) and strictly restricted to their native regions (Gammarus locusta, Gammarus salinus, Gammarus zaddachi, and Gammarus oceanicus). Despite that genetic diversity did not differ between invasive and non-invasive species, we observed that populations of non-invasive species showed a higher degree of genetic differentiation. Furthermore, we found that both geographic and evolutionary distances might explain genetic differentiation in both non-native and native ranges. This suggests that the lack of population genetic structure may facilitate the distribution of mutations that despite arising in the native range may be beneficial in invasive ranges. The fact that evolutionary distances explained genetic differentiation more often than geographic distances points toward that deep lineage divergence holds an important role in the distribution of neutral genetic diversity

Unique mitochondrial DNA lineages in Irish sticklebackpopulations: cryptic refugium or rapid recolonization?

Repeated recolonization of freshwater environments following Pleistocene glaciations has played a major role in the evolution and adaptation of anadromous taxa. Located at the western fringe of Europe, Ireland and Britain were likely recolonized rapidly by anadromous fishes from the North Atlantic following the last glacial maximum (LGM). While the presence of unique mitochondrial haplotypes in Ireland suggests that a cryptic northern refugium may have played a role in recolonization, no explicit test of this hypothesis has been conducted. The three-spined stickleback is native and ubiquitous to aquatic ecosystems throughout Ireland, making it an excellent model species with which to examine the biogeographical history of anadromous fishes in the region. We used mitochondrial and microsatellite markers to examine the presence of divergent evolutionary lineages and to assess broad-scale patterns of geographical clustering among postglacially isolated populations. Our results confirm that Ireland is a region of secondary contact for divergent mitochondrial lineages and that endemic haplotypes occur in populations in Central and Southern Ireland. To test whether a putative Irish lineage arose from a cryptic Irish refugium, we used approximate Bayesian computation (ABC). However, we found no support for this hypothesis. Instead, the Irish lineage likely diverged from the European lineage as a result of postglacial isolation of freshwater populations by rising sea levels. These findings emphasize the need to rigorously test biogeographical hypothesis and contribute further evidence that postglacial processes may have shaped genetic diversity in temperate fauna