Integrability of a conducting elastic rod in a magnetic field

We consider the equilibrium equations for a conducting elastic rod placed in a uniform magnetic field, motivated by the problem of electrodynamic space tethers. When expressed in body coordinates the equations are found to sit in a hierarchy of non-canonical Hamiltonian systems involving an increasing number of vector fields. These systems, which include the classical Euler and Kirchhoff rods, are shown to be completely integrable in the case of a transversely isotropic rod; they are in fact generated by a Lax pair. For the magnetic rod this gives a physical interpretation to a previously proposed abstract nine-dimensional integrable system. We use the conserved quantities to reduce the equations to a four-dimensional canonical Hamiltonian system, allowing the geometry of the phase space to be investigated through Poincar\'e sections. In the special case where the force in the rod is aligned with the magnetic field the system turns out to be superintegrable, meaning that the phase space breaks down completely into periodic orbits, corresponding to straight twisted rods.Comment: 19 pages, 1 figur

Accounting for self-protective responses in randomized response data from a social security survey using the zero-inflated Poisson model

In 2004 the Dutch Department of Social Affairs conducted a survey to assess the extent of noncompliance with social security regulations. The survey was conducted among 870 recipients of social security benefits and included a series of sensitive questions about regulatory noncompliance. Due to the sensitive nature of the questions the randomized response design was used. Although randomized response protects the privacy of the respondent, it is unlikely that all respondents followed the design. In this paper we introduce a model that allows for respondents displaying self-protective response behavior by consistently giving the nonincriminating response, irrespective of the outcome of the randomizing device. The dependent variable denoting the total number of incriminating responses is assumed to be generated by the application of randomized response to a latent Poisson variable denoting the true number of rule violations. Since self-protective responses result in an excess of observed zeros in relation to the Poisson randomized response distribution, these are modeled as observed zero-inflation. The model includes predictors of the Poisson parameters, as well as predictors of the probability of self-protective response behavior.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS135 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Repeated Cross-Sectional Randomized Response Data Taking Design Change and Self-Protective Responses into Account

Abstract. Randomized response (RR) is an interview technique that can be used to protect the privacy of respondents if sensitive questions are posed. This paper explains how to measure change in time if a binary RR question is posed at several time points. In cross-sectional research settings, new insights often gradually emerge. In our setting, a switch to another RR procedure necessitates the development of a trend model that estimates the effect of the covariate time if the dependent variable is measured by different RR designs. We also demonstrate that it is possible to deal with self-protective responses, thus accommodating our trend model with the latest developments in RR data analysis. Keywords: linear trend, longitudinal data, misclassification, randomized response, repeated cross-sections, self-protective responses Randomized response (RR) is an interview technique that can be used if sensitive questions are posed and respondents are reluctant to answer directly In addition to the RR setting, misclassification probabilities occur in several other fields of research. The one most closely related to RR is the postrandomization method (PRAM, Kooiman, Willenborg, & Gouweleeuw, 1997) that misclassifies values of categorical variables using a computerized process after the data are collected to protect the respondents' privacy. PRAM uses RR after the data collection. Misclassification also plays a role in medicine and epidemiology with the probabilities correctly classified as a case (sensitivity) or noncase (specificity), see This paper proposes a model to measure changes in time whenever RR is used to pose sensitive questions at several time points cross-sectionally. The model is illustrated with data from a Dutch repeated cross-sectional study on noncompliance to rules regarding social benefits. Data are collected every 2 years since 2000 and given that measures to prevent regulatory noncompliance are intensified during this period, the question arises as to whether the prevalence of regulatory noncompliance changes over the years and how the change can be modeled. Considering time a covariate, we propose a method to measure the effect of this covariate if the dependent variable is measured by RR. Several aspects of the cross-sectional study at hand make it impossible to use standard analysis methods and necessitate a new approach in the analysis of RR data to deal with research questions of this type. Firstly, the fact that RR variables represent misclassified responses on categorical variables precludes the use of, for example, the linear logit model (Agresti, 2002, p. 180), to test for a linear trend. Using the framework o

Structural and functional variation in soil fungal communities associated with litter bags containing maize leaf

Soil fungi are key players in the degradation of recalcitrant organic matter in terrestrial ecosystems. To examine the organisms and genes responsible for complex organic matter degradation in soil, we tracked changes in fungal community composition and expressed genes in soil adjacent to mesh bags containing maize leaves undergoing decomposition. Using high-throughput sequencing approaches, changes in fungal community composition were determined by targeting 18S rRNA gene sequences, whereas community gene expression was examined via a metatranscriptomic approach. The majority of the 93 000 partial 18S rRNA gene sequences generated, were affiliated with the Ascomycota and Basidiomycota. Fungal diversity was at least 224 operational taxonomic units at the 97% similarity cutoff level. During litter degradation, the relative proportion of Basidiomycota increased, with a decrease in Ascomycota : Basidiomycota ratios over time. The most commonly detected decomposition-associated fungi included Agaricomycetes and Tremellales as well as unclassified Mucoromycotina. The majority of protein families found in the metatranscriptomic data were affiliated to fungal groups described to degrade plant-derived cellulose, such as Mucoraceae, Chaetomiaceae, Sordariaceae, Sebacinaceae, Tremellaceae, Psathyrellaceae and Schizophyllaceae. The combination of high-throughput rRNA gene-based and metatranscriptomic approaches provided perspectives into the organisms and genes involved in complex organic matter in soi

Jaarrond kasteelt van suikerbieten: Een haalbaarheidsstudie ten behoeve van de biobased economy

De potentie van suikerbietenteelt in een kas voor de productie van bouwstenen voor de biorenewables industrie is onderzocht in opdracht van Biorenewables Business Platform van AgentschapNL en de Rabobank. Een kasteelt biedt in vergelijking met de buitenteelt meer mogelijkheden voor klimaatoptimalisatie en productiespreiding. Met behulp van rekenmodellen (kas, gewas, kosten-baten) werd een kwantitatief beeld geschetst van scenario’s betreffende: grond- en substraatteelt, verwarming, diffuus kasdekmateriaal, CO2 dosering, in combinatie met raamventalatie of mechanische koeling, belichting, en meerlagenteelt. De variabele kosten voor energie en CO2 liggen meer dan zeven keer zo hoog dan de financiële opbrengsten. De teelt kan daardoor niet rendabel kan zijn, zeker als de investeringskosten ook worden verdisconteerd. Meerlagenteelt leidt tot een stijging van de productie, maar ook tot een hoger energieverbruik omdat additionele assimilatiebelichting nodig is. Slim gebruik van energiegrids, zeolieten, goedkope CO2, etcetera zal geen oplossing bieden op het niveau van de kas, maar wellicht wel mogelijkheden bieden op hogere aggregatieniveaus. Productie van bieten in de vollegrond is een alternatief, zeker als de productie goed met de keten richting bioplastics wordt afgestemd. Ook kan jaarrond verwerking worden nagestreeft door de oogst- en verwerkingsperiodes op te rekken in combinatie met de opslag van diksap

Treatment Patterns and Use of Immune Checkpoint Inhibitors Among Patients with Metastatic Bladder Cancer in a Dutch Nationwide Cohort

Since 2017, two immune checkpoint inhibitors (ICIs) have become the standard of care for the treatment of metastatic urothelial carcinoma in Europe: pembrolizumab as second-line therapy and avelumab as maintenance therapy. Our aim was to describe the use of ICIs as first and later lines of treatment in patients with metastatic bladder cancer (mBC) in the Netherlands. We identified all patients diagnosed with primary mBC between 2018 and 2021 in the Netherlands from the Netherlands Cancer Registry (NCR). NCR data were supplemented with data from the Dutch nationwide Prospective Bladder Cancer Infrastructure (ProBCI) collected from medical files, with follow-up until death or end of data collection on January 1, 2023. A total of 1525 patients were diagnosed with primary mBC between 2018 and 2021 in the Netherlands. Of these, 34.7% received at least one line of systemic treatment with chemotherapy or ICI. After first-line platinum-based chemotherapy, 34.1% received second-line ICI and 3.9% received maintenance ICI. Among patients who completed or discontinued first-line cisplatin- or carboplatin-based chemotherapy after approval of maintenance ICI in the Netherlands, 40.7% and 19.7% received second-line ICI, and 9.3% and 14.1% received maintenance ICI, respectively. ICI use for mBC treatment has not increased considerably since their introduction in 2017. Future research should assess whether the introduction of maintenance avelumab (available since April 2021 in the Netherlands) has led to increases in the proportion of patients with mBC patients receiving systemic treatment and the proportion receiving ICI. Patient summary: We assessed the rate of immunotherapy use for patients with metastatic bladder cancer in the Netherlands. Since its introduction, immunotherapy has been used in a minority of patients, mostly as second-line treatment after platinum-based chemotherapy.</p

Natural Exon Skipping Sets the Stage for Exon Skipping as Therapy for Dystrophic Epidermolysis Bullosa

Contains fulltext : 214010.pdf (publisher's version ) (Open Access

The Tumor Immune Landscape and Architecture of Tertiary Lymphoid Structures in Urothelial Cancer

Candidate immune biomarkers have been proposed for predicting response to immunotherapy in urothelial cancer (UC). Yet, these biomarkers are imperfect and lack predictive power. A comprehensive overview of the tumor immune contexture, including Tertiary Lymphoid structures (TLS), is needed to better understand the immunotherapy response in UC. We analyzed tumor sections by quantitative multiplex immunofluorescence to characterize immune cell subsets in various tumor compartments in tumors without pretreatment and tumors exposed to preoperative anti-PD1/CTLA-4 checkpoint inhibitors (NABUCCO trial). Pronounced immune cell presence was found in UC invasive margins compared to tumor and stroma regions. CD8+PD1+ T-cells were present in UC, particularly following immunotherapy. The cellular composition of TLS was assessed by multiplex immunofluorescence (CD3, CD8, FoxP3, CD68, CD20, PanCK, DAPI) to explore specific TLS clusters based on varying immune subset densities. Using a k-means clustering algorithm, we found five distinct cellular composition clusters. Tumors unresponsive to anti-PD-1/CTLA-4 immunotherapy showed enrichment of a FoxP3+ T-cell-low TLS cluster after treatment. Additionally, cluster 5 (macrophage low) TLS were significantly higher after pre-operative immunotherapy, compared to untreated tumors. We also compared the immune cell composition and maturation stages between superficial (submucosal) and deeper TLS, revealing that superficial TLS had more pronounced T-helper cells and enrichment of early TLS than TLS located in deeper tissue. Furthermore, superficial TLS displayed a lower fraction of secondary follicle like TLS than deeper TLS. Taken together, our results provide a detailed quantitative overview of the tumor immune landscape in UC, which can provide a basis for further studies

High workload and job stress are associated with lower practice performance in general practice: an observational study in 239 general practices in the Netherlands

Contains fulltext : 80493.pdf (publisher's version ) (Open Access)BACKGROUND: The impact of high physician workload and job stress on quality and outcomes of healthcare delivery is not clear. Our study explored whether high workload and job stress were associated with lower performance in general practices in the Netherlands. METHODS: Secondary analysis of data from 239 general practices, collected in practice visits between 2003 to 2006 in the Netherlands using a comprehensive set of measures of practice management. Data were collected by a practice visitor, a trained non-physician observer using patients questionnaires, doctors and staff. For this study we selected five measures of practice performance as outcomes and six measures of GP workload and job stress as predictors. A total of 79 indicators were used out of the 303 available indicators. Random coefficient regression models were applied to examine associations. RESULTS AND DISCUSSION: Workload and job stress are associated with practice performance.Workload: Working more hours as a GP was associated with more positive patient experiences of accessibility and availability (b = 0.16). After list size adjustment, practices with more GP-time per patient scored higher on GP care (b = 0.45). When GPs provided more than 20 hours per week per 1000 patients, patients scored over 80% on the Europep questionnaire for quality of GP care.Job stress: High GP job stress was associated with lower accessibility and availability (b = 0.21) and insufficient practice management (b = 0.25). Higher GP commitment and more satisfaction with the job was associated with more prevention and disease management (b = 0.35). CONCLUSION: Providing more time in the practice, and more time per patient and experiencing less job stress are all associated with perceptions by patients of better care and better practice performance. Workload and job stress should be assessed by using list size adjusted data in order to realise better quality of care. Organisational development using this kind of data feedback could benefit both patients and GP