Convergence Rates in Dynamic Network Models

The stochastic network model by Britton and Lindholm (Journal of Statistical Physics 3, 2010) describes a class of reasonably realistic dynamics for a complex system with an underlying network structure. In a closed social network, which is modeled by a dynamic random graph, the number of individuals evolves according to a linear birth and death process with per-capita birth rate λ and per-capita death rate µ < λ. A random social index is assigned to each individual at birth, which controls the rate at which connections to other individuals are created. Britton and Lindholm give a somewhat rough proof for the convergence of the degree distribution in this model towards a mixed Poisson distribution. We derive a rate for this convergence giving precise arguments. In order to do so, we deduce the degree distribution at finite time and derive an approximation result for mixed Poisson distributions to compute an upper bound for the total variation distance to the asymptotic degree distribution. We treat the pure birth case and the general case separately and obtain that the degree distribution converges exponentially fast in time in terms of the total variation distance. We compare the model to several other network models and find further interesting results for the model. In particular, we show that the asymptotic degree distribution can exhibit power law tails, which makes it an interesting alternative to the famous preferential attachment models. We finally add a spatial component to the model and find convergence rates for this extended model as well. We prove several general results about linear birth and death processes along the way. Most notably, we derive the age distribution of an individual picked uniformly at random at some finite time by exploiting a bijection between the birth and death tree and a contour process

The effect of inadvertent systemic hypothermia after mechanical thrombectomy in patients with large-vessel occlusion stroke

Background and aimsPostinterventional hypothermia is a frequent complication in patients with large-vessel occlusion strokes (LVOS) after mechanical thrombectomy (MT). This inadvertent hypothermia might potentially have neuroprotective but also adverse effects on patients’ outcomes. The aim of the study was to determine the rate of hypothermia in patients with LVOS receiving MT and its influence on functional outcome.MethodsWe performed a monocentric, retrospective study using a prospectively derived databank, including all LVOS patients receiving MT between 2015 and 2021. Predictive values of postinterventional body temperature and body temperature categories (hyperthermia (≥38°C), normothermia (35°C–37.9°C), and hypothermia (&lt;35°C)) on functional outcome were analyzed using multivariable Bayesian logistic regression models. Favorable outcome was defined as modified Rankin Scale (mRS) ≤3.ResultsOf the 480 included LVOS patients with MT (46.0% men; mean ± SD age 73 ± 12.9 years), 5 (1.0%) were hyperthermic, 382 (79.6%) normothermic, and 93 (19.4%) hypothermic. Postinterventional hypothermia was significantly associated with unfavorable functional outcome (mRS &gt; 3) after 90 days (OR 2.06, 95% CI 1.01–4.18, p = 0.045). For short-term functional outcome, patients with hypothermia had a higher discharge NIHSS (OR 1.38, 95% CI 1.06 to 1.79, p = 0.015) and a higher change of NIHSS from admission to discharge (OR 1.35, 95% CI 1.03 to 1.76, p = 0.029).ConclusionApproximately a fifth of LVOS patients in this cohort were hypothermic after MT. Hypothermia was an independent predictor of unfavorable functional outcomes. Our findings warrant a prospective trial investigating active warming during MT

COVID-19 – Auswirkung auf das Verhalten von Tumorpatienten

Hintergrund: Die Coronavirus-Krankheit-2019 (COVID-19) gefährdet Tumorpatienten durch schwere Krankheitsverläufe. Ziel der Arbeit: Die vorliegende Untersuchung beschäftigt sich mit dem Impf- und Sicherheitsverhalten von Tumorpatienten bzgl. COVID-19. Material und Methoden: Von 01/2022 bis 03/2022 wurden an drei medizinischen Versorgungszentren (MVZ) in Niederbayern alle Patienten eingeladen, an einer COVID- 19-Umfrage teilzunehmen. Hierfür wurde ein Fragebogen mit den Schwerpunkten Schutzmaßnahmen, Impfungen und erlebte Sicherheit entwickelt. Die statistische Auswertung erfolgte deskriptiv und mittels des exakten Tests nach Fisher sowie mit multivariablen logistischen Regressionsmodellen. Ergebnisse: 1228 Fragebögen konnten ausgewertet werden. 6% der Patienten waren nicht geimpft. Der Großteil der geimpften Patienten geht davon aus, durch die Impfung vor einem schweren Krankheitsverlauf bzw. komplett geschützt zu sein. Sicherheitsmaßnahmen wurden außerhalb der Familie deutlich strenger gehandhabt als innerhalb. Sicherheitsvorkehrungen in onkologischen Praxen wurden begrüßt. Diskussion: Tumorpatienten zeigen bzgl. einer COVID-19-Infektion ein hohes Sicherheitsbedürfnis, was sich im Einhalten von Schutzmaßnahmen und in der Akzeptanz von Sicherheitsvorkehrungen widerspiegelt. Beide werden im häuslichen Bereich allerdings deutlich weniger eingehalten, sodass der Aufklärung und Impfung von Angehörigen große Bedeutung zukommt. Nichtgeimpfte Tumorpatienten gaben als Grund der Impfverweigerung neben Angst vor Nebenwirkungen (64%) insbesondere auch Angst vor einer Krankheitsverschlechterung (51 %) an, sodass die Aufklärung dieser Patientengruppe hinsichtlich Impfung und Sicherheitsmaßnahmen besonders intensiv durchgeführt werden sollte

Use of symptom-focused oncological cancer therapies in hospices: a retrospective analysis

Background There is controversy regarding the practical implementation of symptom-focused oncological cancer therapies to hospice residents. In this study, we aim to analyse the use and indication of supportive-oncological cancer therapies in hospices. Methods We conducted a retrospective survey of all residents of two hospice centres in the government district of Lower Bavaria, Germany. Hospice 1 (H1) was a member of an oncological-palliative medical network, and hospice 2 (H2) was independently organized. The evaluation period was the first 40 months after the opening of the respective hospice care centre. Demographical and epidemiological data as well as indications and type of supportive-oncological cancer therapies were recorded. A descriptive analysis and statistical tests were performed. Results Of the 706 residents, 645 had an underlying malignant disease. The average age was 72 years and the mean residence time was 28 days. The most frequent cancer types were gastrointestinal cancers, gynaecological cancers and bronchial carcinomas. Overall 39 residents (33 in H1 and 6 in H2,p < 0.01) received symptom-focused oncological cancer therapy. The average age of these residents was 68 years, and the mean residence time was 55 days. The most common therapeutic indications were dyspnoea and pain. The most common symptom-focused oncological cancer therapies were bisphosphonates, transfusions (erythrocyte- and platelet- concentrates), radiotherapy and anti-proliferative drugs (chemotherapy, anti-hormonal- and targeted- therapies). Patients with therapy lived significantly longer than patients without therapy (p < 0.01). Conclusions Symptom-focused oncological cancer therapies can be implemented in hospices; however, their implementation seems to require certain structural and organizational prerequisites as well as careful patient selection. As a palliative medical approach, the focus is to ameliorate the symptoms and not prolong life. Symptom-focused oncology treatment could be a further and important part for the therapy of hospice patients in the future

Measurement of Scapholunate Joint Space Width on Real-Time MRI—A Feasibility Study

Introduction: The scapholunate interosseous ligament is pivotal for wrist stability, and its impairment can result in instability and joint degeneration. This study explores the application of real-time MRI for dynamic assessment of the scapholunate joint during wrist motion with the objective of determining its diagnostic value in efficacy in contrast to static imaging modalities. Materials and Methods: Ten healthy participants underwent real-time MRI scans during wrist ab/adduction and fist-clenching maneuvers. Measurements were obtained at proximal, medial, and distal landmarks on both dynamic and static images with statistical analyses conducted to evaluate the reliability of measurements at each landmark and the concordance between dynamic measurements and established static images. Additionally, inter- and intraobserver variabilities were evaluated. Results: Measurements of the medial landmarks demonstrated the closest agreement with static images and exhibited the least scatter. Distal landmark measurements showed a similar level of agreement but with increased scatter. Proximal landmark measurements displayed substantial deviation, which was accompanied by an even greater degree of scatter. Although no significant differences were observed between the ab/adduction and fist-clenching maneuvers, both inter- and intraobserver variabilities were significant across all measurements. Conclusions: This study highlights the potential of real-time MRI in the dynamic assessment of the scapholunate joint particularly at the medial landmark. Despite promising results, challenges such as measurement variability need to be addressed. Standardization and integration with advanced image processing methods could significantly enhance the accuracy and reliability of real-time MRI, paving the way for its clinical implementation in dynamic wrist imaging studies

Comparative evaluation of clinical and cerebrospinal fluid biomarker characteristics in rapidly and non-rapidly progressive Alzheimer’s disease

Abstract Background Rapidly progressive forms of Alzheimer’s disease (rpAD) are increasingly recognized and may have a prevalence of up to 30% of patients among all patients with Alzheimer’s disease (AD). However, insights about risk factors, underlying pathophysiological processes, and clinical characteristics of rpAD remain controversial. This study aimed to gain a comprehensive picture of rpAD and new insights into the clinical manifestation to enable a better interpretation of disease courses in clinical practice as well as in future clinical studies. Methods Patients (n = 228) from a prospective observational study on AD were selected and categorized into rpAD (n = 67) and non-rpAD (n = 161) disease groups. Patients were recruited through the German Creutzfeldt-Jakob disease surveillance center and the memory outpatient clinic of the Göttingen University Medical Center, representing diverse phenotypes of the AD population. Biomarkers and clinical presentation were assessed using standardized protocols. A drop of ≥ MMSE 6 points within 12 months defined rapid progressors. Results Lower CSF Amyloid beta 1–42 concentrations (p = 0.048), lower Amyloid beta 42/40 ratio (p = 0.038), and higher Tau/Amyloid-beta 1–42 ratio, as well as pTau/Amyloid-beta 1–42 ratio (each p = 0.004) were associated with rpAD. Analyzes in a subset of the cohort (rpAD: n = 12; non-rpAD: n = 31) showed higher CSF NfL levels in rpAD (p = 0.024). Clinically, rpAD showed earlier impairment of functional abilities (p < 0.001) and higher scores on the Unified Parkinson’s Disease Rating Scale III (p < 0.001), indicating pronounced extrapyramidal motor symptoms. Furthermore, cognitive profiles (adjusted for overall cognitive performance) indicated marked deficits in semantic (p = 0.008) and phonematic (0.023) verbal fluency tests as well as word list learning (p = 0.007) in rpAD compared to non-rpAD. The distribution of APOE genotypes did not differ significantly between groups. Conclusions Our results suggest that rpAD is associated with distinct cognitive profiles, earlier occurrence of non-cognitive symptoms, extrapyramidal motoric disturbance, and lower Amyloid-beta 1–42 concentrations in the CSF. The findings may help to characterize a distinct phenotype of rpAD and estimate prognosis based on clinical characteristics and biomarker results. However, an important future goal should be a unified definition for rpAD to enable targeted study designs and better comparability of the results

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