Estimating Time-Varying Effects of Prognostic Factors for Stomach Cancer Patients within a Dynamic Grouped Cox Model

We describe the identification of prognostic factors in the framework of a completely resected stomach cancer survival-study. For the analysis the dynamic grouped Cox-Model was used allowing for time-varying covariate effects. Therefore the hazard rate might be non-proportional. As estimation concept we applied the posterior mode, computed by iteratively weighted Kalman filtering and smoothing steps. The medical study and questions are described, the statistical method is illustrated, the results are given and interpreted and the method is discussed

Utility of Fear Severity and Individual Resilience Scoring as a Surge Capacity, Triage Management Tool during Large-Scale, Bio-event Disasters

Threats of bioterrorism and emerging infectious disease pandemics may result in fear related consequences. Fear based signs and symptoms, if left undetected and untreated, may be extremely debilitating and lead to chronic problems with risk of permanent damage to the brain’s locus coeruleus stress response circuits. The triage management of susceptible, exposed, and infectious victims seeking care must be sensitive and specific enough to identify individuals with excessive levels of fear in order to address the nuances of fear-based symptoms at the initial point of contact. These acute conditions, which include hyper-vigilant fear, are best managed by timely and effective information, rapid evaluation, and possibly medication that uniquely addresses the locus-coeruleus driven noradrenalin overactivation. This article recommends that a fear and resilience (FR) checklist be included as an essential triage tool to identify those most at risk. This checklist has the utility of rapid usage and capacity to respond to limitations brought about by surge capacity requirements. Whereas the utility of such a checklist is evident, predictive validity studies will be required in the future. It is important to note that a unique feature of the FR Checklist is that in addition to identifying individuals who are emotionally, medically, and socially hypo-resilient, it simultaneously identifies individuals who are hyper-resilient who can be asked to volunteer and thus rapidly expand the surge capacity

The highly connected even-cycle and even-cut matroids

The classes of even-cycle matroids, even-cycle matroids with a blocking pair, and even-cut matroids each have hundreds of excluded minors. We show that the number of excluded minors for these classes can be drastically reduced if we consider in each class only the highly connected matroids of sufficient size.Comment: Version 2 is a major revision, including a correction of an error in the statement of one of the main results and improved exposition. It is 89 pages, including a 33-page Jupyter notebook that contains SageMath code and that is also available in the ancillary file

On perturbations of highly connected dyadic matroids

Geelen, Gerards, and Whittle [3] announced the following result: let $q = p^k$ be a prime power, and let $\mathcal{M}$ be a proper minor-closed class of $\mathrm{GF}(q)$-representable matroids, which does not contain $\mathrm{PG}(r-1,p)$ for sufficiently high $r$. There exist integers $k, t$ such that every vertically $k$-connected matroid in $\mathcal{M}$ is a rank-$(\leq t)$ perturbation of a frame matroid or the dual of a frame matroid over $\mathrm{GF}(q)$. They further announced a characterization of the perturbations through the introduction of subfield templates and frame templates. We show a family of dyadic matroids that form a counterexample to this result. We offer several weaker conjectures to replace the ones in [3], discuss consequences for some published papers, and discuss the impact of these new conjectures on the structure of frame templates.Comment: Version 3 has a new title and a few other minor corrections; 38 pages, including a 6-page Jupyter notebook that contains SageMath code and that is also available in the ancillary file

On the existence of asymptotically good linear codes in minor-closed classes

Let $\mathcal{C} = (C_1, C_2, \ldots)$ be a sequence of codes such that each $C_i$ is a linear $[n_i,k_i,d_i]$-code over some fixed finite field $\mathbb{F}$, where $n_i$ is the length of the codewords, $k_i$ is the dimension, and $d_i$ is the minimum distance. We say that $\mathcal{C}$ is asymptotically good if, for some $\varepsilon > 0$ and for all $i$, $n_i \geq i$, $k_i/n_i \geq \varepsilon$, and $d_i/n_i \geq \varepsilon$. Sequences of asymptotically good codes exist. We prove that if $\mathcal{C}$ is a class of GF$(p^n)$-linear codes (where $p$ is prime and $n \geq 1$), closed under puncturing and shortening, and if $\mathcal{C}$ contains an asymptotically good sequence, then $\mathcal{C}$ must contain all GF$(p)$-linear codes. Our proof relies on a powerful new result from matroid structure theory

Bruxism and autonomic activity

not applicabl

Vector and axialvector mesons at nonzero temperature within a gauged linear sigma model

We consider vector and axialvector mesons in the framework of a gauged linear sigma model with chiral $U(N_f)_R \times U(N_f)_L$ symmetry. For $N_f=2$, we investigate the behavior of the chiral condensate and the meson masses as a function of temperature by solving a system of coupled Dyson-Schwinger equations derived via the 2PI formalism in double-bubble approximation. We find that the inclusion of vector and axialvector mesons tends to sharpen the chiral transition. Within our approximation scheme, the mass of the $\rho$ meson increases by about 100 MeV towards the chiral transition.Comment: 20 pages, 6 figure

An obstacle to a decomposition theorem for near-regular matroids

Seymour's Decomposition Theorem for regular matroids states that any matroid representable over both GF(2) and GF(3) can be obtained from matroids that are graphic, cographic, or isomorphic to R10 by 1-, 2-, and 3-sums. It is hoped that similar characterizations hold for other classes of matroids, notably for the class of near-regular matroids. Suppose that all near-regular matroids can be obtained from matroids that belong to a few basic classes through k-sums. Also suppose that these basic classes are such that, whenever a class contains all graphic matroids, it does not contain all cographic matroids. We show that in that case 3-sums will not suffice.Comment: 11 pages, 1 figur