A Wiener--Hopf Monte Carlo simulation technique for L\'{e}vy processes

We develop a completely new and straightforward method for simulating the joint law of the position and running maximum at a fixed time of a general L\'{e}vy process with a view to application in insurance and financial mathematics. Although different, our method takes lessons from Carr's so-called "Canadization" technique as well as Doney's method of stochastic bounds for L\'{e}vy processes; see Carr [Rev. Fin. Studies 11 (1998) 597--626] and Doney [Ann. Probab. 32 (2004) 1545-1552]. We rely fundamentally on the Wiener-Hopf decomposition for L\'{e}vy processes as well as taking advantage of recent developments in factorization techniques of the latter theory due to Vigon [Simplifiez vos L\'{e}vy en titillant la factorization de Wiener-Hopf (2002) Laboratoire de Math\'{e}matiques de L'INSA de Rouen] and Kuznetsov [Ann. Appl. Probab. 20 (2010) 1801--1830]. We illustrate our Wiener--Hopf Monte Carlo method on a number of different processes, including a new family of L\'{e}vy processes called hypergeometric L\'{e}vy processes. Moreover, we illustrate the robustness of working with a Wiener--Hopf decomposition with two extensions. The first extension shows that if one can successfully simulate for a given L\'{e}vy processes then one can successfully simulate for any independent sum of the latter process and a compound Poisson process. The second extension illustrates how one may produce a straightforward approximation for simulating the two-sided exit problem.Comment: Published in at http://dx.doi.org/10.1214/10-AAP746 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Collective action and the intensity of between-group competition in nonhuman primates

The importance of between-group competition in the social evolution of animal societies is controversial, particularly with respect to understanding the origins and maintenance of cooperation in our own species. Among primates, aggressive between-group encounters are often rare or strikingly absent, a phenomenon that in some species has been ascribed to the presence of collective action problems. Here, we report on a series of comparative tests that show that the intensity of between-group contest competition is indeed lower in species that experience a collective action problem while controlling for predictions from an "ideal gas” model of animal encounters and general species' ecology. Species that do not succumb to the collective action problem are either cooperative breeders, are characterized by philopatry of the dominant sex, or live in relatively small groups with few individuals of this dominant sex. This implies that collective action problems are averted either through shared genes and benefits or a by-product mutualism in which the territorial behavior of some privileged individuals is not affected by the behavior of others. We conclude that across the primate taxon, the intensity of between-group competition is predominantly constrained by a social dilemma among group members, rather than ecological conditions, and that the collective action problem is thus an important selective pressure in the evolution of primate (including human) cooperation and socialit

Zingeving op de zorgboerderij. Een casestudy bij drie zorgboerderijen naar de mogelijke invloed van de zorgboerderijen op de zingeving bij deelnemers met een psychische hulpvraag

Dit kwalitatieve sociaalwetenschappelijke onderzoek beschrijft of er een mogelijke invloed is van zorgboerderijen op de zingeving van deelnemers met een psychische hulpvraag. Aanleiding van dit onderzoek vormt de kennislacune op het gebied van (de mogelijke invloed van) zingeving binnen de gezondheidszorg en specifiek bij deelnemers aan zorgboerderijen. Zorgboerderijen vormen een groeiend zorgsegment. Daarbij streven zorgboerderijen naar professionalisering van de zorg. De aanname geldt dat zingeving mogelijk van belang is voor het welzijn en functioneren van mensen. Met het oog op de zorgkwaliteit bij zorgboerderijen is onderzoek naar zingeving bij zorgboerderijen daarom van belang. Het onderzoek is uitgevoerd aan de hand van een multiple casestudy bij drie zorgboerderijen in Nederland. Onderzoek vond plaats middels observatiedagen en interviews met vijf hulpverleners en zeven deelnemers. Omdat een psychische hulpvraag aanleiding kan zijn tot zingevingsvraagstukken, richt deze studie zich op deelnemers met een psychische hulpvraag. Vanuit de bestaande beschrijvingen van zingeving is een tijdelijke werkdefinitie van zingeving gevormd, met aandacht voor de alledaagse zinbeleving. Zingeving is geoperationaliseerd via de zogenaamde ‘oervragen’ van Anbeek. Het blijkt dat de zorgboerderijen een zogenaamde (tijdelijke) ‘gebroken gemeenschap’ vormen voor (kwetsbare) deelnemers met een zorgvraag. Binnen deze context geven diverse elementen kans op beïnvloeding van de zingeving bij de deelnemers. De dieren op de zorgboerderij bieden afleiding en troost bij ervaringen van kwetsbaarheid. Andere mogelijk zingevende elementen zijn niet-natuur gerelateerde activiteiten, omgang met andere kwetsbare deelnemers, de sfeer van veiligheid en acceptatie voor ieders kwetsbaarheid die gemotiveerde hulpverleners scheppen en de mogelijkheid tot persoonlijke ontwikkeling. Bij dit onderzoek dient in het vizier gehouden te worden wanneer sprake is van zingeving of van een psychologische invloed die kan leiden tot zingeving. Tevens spelen de culturele en economische kenmerken van de onderzoeksgroep een mogelijke rol bij de manier van denken en spreken over zingeving. Trefwoorden: zingeving, levensvragen, zorgboerderij, zorglandbouw, herstelbeweging, psychische hulpvraa

The use of information in online healthcare provider choice

In order to evaluate and facilitate the provision of health information online, we must first understand how it is perceived by those who use it. Two important considerations in research on patients’ information use in online healthcare provider choice are the need for a conceptual framework for studying information types and methods for studying information use. Therefore, our first contribution lies in using Donabedian's structure-process-outcome model of healthcare quality to identify specific patterns of preference and information use in online healthcare provider choice, and differences in information use between two healthcare provider types. Our second contribution lies in identifying differences in results between data collection methods (importance rating/selection, concurrent self-report of online information use and retrospective information use) in relation to choice tasks. In a mixed-methods design, provider type (primary and secondary care) was systematically varied during participants’ use of the infomediary NHS Choices. Participants preferred process topics over structure topics, in contrast with the results of concurrent and retrospective self-report. We conclude that the differences in results between the types of data collection method reflect underlying differences in choice task. Future research should address the use of novel infomediary user-interfaces, and infomediaries in relation to the use of other information sources and (e-)health literacy

Targeting Fibronectin to Overcome Remyelination Failure in Multiple Sclerosis:The Need for Brain- and Lesion-Targeted Drug Delivery

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease with unknown etiology that can be characterized by the presence of demyelinated lesions. Prevailing treatment protocols in MS rely on the modulation of the inflammatory process but do not impact disease progression. Remyelination is an essential factor for both axonal survival and functional neurological recovery but is often insufficient. The extracellular matrix protein fibronectin contributes to the inhibitory environment created in MS lesions and likely plays a causative role in remyelination failure. The presence of the blood-brain barrier (BBB) hinders the delivery of remyelination therapeutics to lesions. Therefore, therapeutic interventions to normalize the pathogenic MS lesion environment need to be able to cross the BBB. In this review, we outline the multifaceted roles of fibronectin in MS pathogenesis and discuss promising therapeutic targets and agents to overcome fibronectin-mediated inhibition of remyelination. In addition, to pave the way for clinical use, we reflect on opportunities to deliver MS therapeutics to lesions through the utilization of nanomedicine and discuss strategies to deliver fibronectin-directed therapeutics across the BBB. The use of well-designed nanocarriers with appropriate surface functionalization to cross the BBB and target the lesion sites is recommended

Total Endovascular Repair of the Aortic Arch:Initial Experience in the Netherlands

Background. We report procedural and early results in the Netherlands of the Relay Branch device (Terumo Aortic, Sunrise, FL) for total endovascular repair of the aortic arch. Methods. Between 2014 and 2018, all consecutive patients who received the Aortic Relay double-branched stent graft in the Netherlands were included in a multicenter, retrospective registry. Results. The Relay Branch device was used in 11 patients to treat saccular (n = 4), fusiform (n = 5), or false aneurysms (n = 2) in the aortic arch. Patients were deemed unfit or extreme high-risk for open (redo) surgery. The brachiocephalic trunk and left common carotid artery were branched using a retrograde approach in all cases. Additional surgical left subclavian artery revascularization was performed in 8 patients. The main device and the branches were successfully introduced, positioned, and deployed with complete exclusion of the aortic pathology in all patients (100% technical success). There was no retrograde type A dissection or conversion to open surgery. Two procedure-related deaths occurred, both caused by perioperative or postoperative strokes. There were 2 minor strokes with full recovery. One patient recovered from transient paraplegia after spinal fluid drainage. No permanent paraplegia was observed. Follow-up imaging showed persistent adequate exclusion of aortic arch pathology. Mean follow-up was 17 months (range, 3-42 months). Conclusions. Total endovascular aortic arch repair using the Relay Branch device is technically feasible and effective in excluding aortic arch pathology. The observed stroke rate in the initial experience, however, was considerable. Although appealing, this new less-invasive technique should be carefully introduced and its progress thoroughly evaluated. (C) 2020 by The Society of Thoracic Surgeon

Noise reduction strategies in metagenomic chromosome confirmation capture to link antibiotic resistance genes to microbial hosts

The gut microbiota is a reservoir for antimicrobial resistance genes (ARGs). With current sequencing methods, it is difficult to assign ARGs to their microbial hosts, particularly if these ARGs are located on plasmids. Metagenomic chromosome conformation capture approaches (meta3C and Hi-C) have recently been developed to link bacterial genes to phylogenetic markers, thus potentially allowing the assignment of ARGs to their hosts on a microbiome-wide scale. Here, we generated a meta3C dataset of a human stool sample and used previously published meta3C and Hi-C datasets to investigate bacterial hosts of ARGs in the human gut microbiome. Sequence reads mapping to repetitive elements were found to cause problematic noise in, and may importantly skew interpretation of, meta3C and Hi-C data. We provide a strategy to improve the signal-to-noise ratio by discarding reads that map to insertion sequence elements and to the end of contigs. We also show the importance of using spike-in controls to quantify whether the cross-linking step in meta3C and Hi-C protocols has been successful. After filtering to remove artefactual links, 87 ARGs were assigned to their bacterial hosts across all datasets, including 27 ARGs in the meta3C dataset we generated. We show that commensal gut bacteria are an important reservoir for ARGs, with genes coding for aminoglycoside and tetracycline resistance being widespread in anaerobic commensals of the human gut

Picturing and modeling catchments by representative hillslopes

This study explores the suitability of a single hillslope as a parsimonious representation of a catchment in a physically based model. We test this hypothesis by picturing two distinctly different catchments in perceptual models and translating these pictures into parametric setups of 2-D physically based hillslope models. The model parametrizations are based on a comprehensive field data set, expert knowledge and process-based reasoning. Evaluation against streamflow data highlights that both models predicted the annual pattern of streamflow generation as well as the hydrographs acceptably. However, a look beyond performance measures revealed deficiencies in streamflow simulations during the summer season and during individual rainfall–runoff events as well as a mismatch between observed and simulated soil water dynamics. Some of these shortcomings can be related to our perception of the systems and to the chosen hydrological model, while others point to limitations of the representative hillslope concept itself. Nevertheless, our results confirm that representative hillslope models are a suitable tool to assess the importance of different data sources as well as to challenge our perception of the dominant hydrological processes we want to represent therein. Consequently, these models are a promising step forward in the search for the optimal representation of catchments in physically based models