Data-adaptive harmonic analysis of oceanic waves and turbulent flows.

We introduce new features of data-adaptive harmonic decomposition (DAHD) that are showcased to characterize spatiotemporal variability in high-dimensional datasets of complex and mutsicale oceanic flows, offering new perspectives and novel insights. First, we present a didactic example with synthetic data for identification of coherent oceanic waves embedded in high amplitude noise. Then, DAHD is applied to analyze turbulent oceanic flows simulated by the Regional Oceanic Modeling System and an eddy-resolving three-layer quasigeostrophic ocean model, where resulting spectra exhibit a thin line capturing nearly all the energy at a given temporal frequency and showing well-defined scaling behavior across frequencies. DAHD thus permits sparse representation of complex, multiscale, and chaotic dynamics by a relatively few data-inferred spatial patterns evolving with simple temporal dynamics, namely, oscillating harmonically in time at a given single frequency. The detection of this low-rank behavior is facilitated by an eigendecomposition of the Hermitian cross-spectral matrix and resulting eigenvectors that represent an orthonormal set of global spatiotemporal modes associated with a specific temporal frequency, which in turn allows to rank these modes by their captured energy and across frequencies, and allow accurate space-time reconstruction. Furthermore, by using a correlogram estimator of the Hermitian cross-spectral density matrix, DAHD is both closely related and distinctly different from the spectral proper orthogonal decomposition that relies on Welch's periodogram as its estimator method.

[Clinicomorphological characteristics of colonic circulatory changes in children with organic and functional colostasis].

Acute colonic perfusion impairments (thrombosis, infarction, and ischemia) have evident clinical manifestations and are reasonably well described in the literature. At the same time, the problems of chronic peripheral circulatory disorder in the large bowel and the impact of the disorder on its motility are inadequately considered. By summarizing the data available in the literature and their findings, the authors consider the etiology and pathogenesis of organic and functional colostasis in the context of changes in the colonic angioarchitectonics.

[Modernization of methods for tissue sampling and preparation for a histological study at autopsy].

Preparation of autopsy material for a histological study for correct diagnosis is not less important than that of a biopsy specimen. Based on their accumulated experience, the authors propose a number of modernizations to prepare autopsy material for the study of lung, bone marrow, and intestinal abnormalities, which require no higher work intensity, but at the same time contribute to a unified approach to investigating tissues and organs in certain pathological processes in pediatric care.