A note on the full non-linear stability of inviscid, planar flows with constant relative vorticity

The non-linear stability of inviscid, planar flows with constant relative vorticity is proved in the context of the quasi-geostrophic shallow-water theory, for simply connected fluid domains of arbitrary shape. First, the result is obtained relative to the enstrophy and kinetic energy norms and, then, it is extended to a “generalised energy” norm which is expressed through the former

On the dynamics of quasi-geostrophic intergyre gyres

An important aspect of the present climatic change concerns the wind-stress anomalies over the ocean. It is possible to associate to them a special current field, which appears between the subtropical and the subpolar gyres and is known as intergyre gyre. In the present paper we investigate its dynamics by including recent models of stochastic wind field into the classical model of ocean circulation at the basin scale of Rhines and Young. In the framework of an analytical approach, developed at the geostrophic level of approximation, we explore the circulation patterns of this recently discovered characteristic of double gyres

On the benthic Ekman layer

A review of the standard model of the benthic Ekman layer is presented and reformulated in terms of relative vorticity in place of horizontal current. In this context, the possibility to use mixed boundary conditions to model this layer is explored. The related model solutions can be cast into two main groups: the first is a generalization of the classical Ekman result, while the second one has some unexpected features which are problematic with respect to the Ekman pumping process. An investigation on the finite amplitude stability via the Lyapunov method shows that solutions belonging to the first group are stable while, in the second group, solutions are unstable. This fact poses a physical constraint to the set of the admissible boundary conditions. Finally, a connection between mass transport and boundary condition at the sea floor is numerically investigated

Water Mass Transformations in the Southern Ocean Diagnosed from Observations: Contrasting Effects of Air-Sea Fluxes and Diapycnal Mixing

Abstract Transformation and formation rates of water masses in the Southern Ocean are estimated in a neutral-surface framework using air–sea fluxes of heat and freshwater together with in situ estimates of diapycnal mixing. The air–sea fluxes are taken from two different climatologies and a reanalysis dataset, while the diapycnal mixing is estimated from a mixing parameterization applied to five years of Argo float data. Air–sea fluxes lead to a large transformation directed toward lighter waters, typically from −45 to −63 Sv (1 Sv ≡ 106 m3 s−1) centered at γ = 27.2, while interior diapycnal mixing leads to two weaker peaks in transformation, directed toward denser waters, 8 Sv centered at γ = 27.8, and directed toward lighter waters, −16 Sv centered at γ = 28.3. Hence, air–sea fluxes and interior diapycnal mixing are important in transforming different water masses within the Southern Ocean. The transformation of dense to lighter waters by diapycnal mixing within the Southern Ocean is slightly larger, though comparable in magnitude, to the transformation of lighter to dense waters by air–sea fluxes in the North Atlantic. However, there are significant uncertainties in the authors' estimates with errors of at least ±5 W m−2 in air–sea fluxes, a factor 4 uncertainty in diapycnal mixing and limited coverage of air–sea fluxes in the high latitudes and Argo data in the Pacific. These water mass transformations partly relate to the circulation in density space: air–sea fluxes provide a general lightening along the core of the Antarctic Circumpolar Current and diapycnal diffusivity is enhanced at middepths along the current.</jats:p

Measuring a Light Neutralino Mass at the ILC: Testing the MSSM Neutralino Cold Dark Matter Model

The LEP experiments give a lower bound on the neutralino mass of about 46 GeV which, however, relies on a supersymmetric grand unification relation. Dropping this assumption, the experimental lower bound on the neutralino mass vanishes completely. Recent analyses suggest, however, that in the minimal supersymmetric standard model (MSSM), a light neutralino dark matter candidate has a lower bound on its mass of about 7 GeV. In light of this, we investigate the mass sensitivity at the ILC for very light neutralinos. We study slepton pair production, followed by the decay of the sleptons to a lepton and the lightest neutralino. We find that the mass measurement accuracy for a few-GeV neutralino is around 2 GeV, or even less if the relevant slepton is sufficiently light. We thus conclude that the ILC can help verify or falsify the MSSM neutralino cold dark matter model even for very light neutralinos.Comment: 7 pages, 1 figure; references adde

Desafios E Possibilidades Para A Profissionalização Da Pesquisa Científica Em Direito

The main objective of this paper is to present some considerations about scientific research in Law as a professional career. This paper departs from a historical rescue on the institutionalization of Bachelor of Law in Brazil, as well as postgraduate studies in this area, to reflect on the contradictions present in the field about the meanings of research in Law. Without forgetting the instrumental character of Law by maintaining and creating elites in Brazil, we present in the text strategies for permanence and maintenance in academic research as an option for professional practice in Law. In the final considerations, we register some questions for future reflections.Este artigo tem como objetivo central apresentar algumas considerações sobre a pesquisa científica na área do Direito enquanto carreira profissional. O artigo parte de um resgate histórico sobre a institucionalização do bacharelismo em Direito no país, bem como da pós-graduação nesta área, para refletir acerca das contradições presentes no campo sobre os sentidos da pesquisa em Direito. Sem se esquecer do caráter instrumental de manutenção e criação de elites do Brasil, apresentamos no texto estratégias de permanência e manutenção na pesquisa acadêmica enquanto opção de atuação profissional no Direito. Nas considerações finais, registramos algumas questões para futuras reflexões

[Pathology of chronic obstructive pulmonary disease]

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disorder of the lung characterized by poorly reversible airflow limitation. It is not a unique disease entity but rather a complex of conditions which include emphysema, chronic bronchitis and, sometimes, asthma. Moreover, COPD is a progressive disease often associated with exacerbations. Cigarette smoking, which is the most important risk factor for the development of COPD, induces pathological changes involving lung parenchyma, peripheral airways and central airways. Since lung parenchyma and peripheral airways are the sites responsible for airflow limitation and central airways are the main site of mucus hypersecretion, pathological changes in these compartments may be relevant in the development of COPD

Терагерцовый сканирующий рефлектометр для визуализации строения полимерных конструкций в аддитивном производстве

The results of the development and practical application of a quasi-optical system for reflectometry of objects in the terahertz frequency range for analyzing the structure in additive manufacturing of objects are presented. A backward-wave oscillator is used for continuous generation of electromagnetic radiation; an acousto-optic converter (Golay cell) is applied as a detector. The reflectometer is controlled by personal computer through the L-card E 154 input-output module and the standard digital-to-analog converter of the STD-21 spectrometer. The system is tested at the frequency of 874 GHz on the 3D-printed composite structure sample. Our paper is terahertz reflectometer with a source of continuous monochromatic electromagnetic radiation based on a backward wave oscillator is presented. The purpose of this work in creating a scanning THz reflectometer is considered to have been achieved. At the same time, the following tasks are solved: a quasi-optical scheme of the reflectometer is selected and assembled; the hardware part of the system (all mechanisms and components) is implemented; a program for controlling the radiation intensity registration system is adapted for this task; the test sample is manufactured using 3D printing technology, the THz reflectometer is tested. The obtained practical results of registration of the two-dimensional distribution of the reflection coefficient show that the use of THz radiation is promising for visualizing the structure of structures obtained by additive technology. Further development of the project is planned by changing the construction of the positioning mechanism, which will provide micrometric calibration of the sample holder relative to the diaphragm. The use of the quasi-optical scheme of the two-beam interferometer for recording the phase distribution and amplitude of reflected THz radiation will allow obtaining information about the spatial location of defects (inhomogeneities) of products obtained by additive technology. Представлены результаты разработки и практического применения в аддитивном производстве системы рефлектометрии объектов в терагерцовом диапазоне частот для анализа структуры. Для непрерывной генерации электромагнитного излучения применялась лампа обратной волны, в качестве детектора использовался акустооптический преобразователь (Ячейка Голея). Управление рефлектометром реализовано с персонального компьютера через модуль ввода-вывода Lcard E154 и штатный цифро-аналоговый преобразователь спектрометра СТД-21. Тестирование системы произведено на частоте 874 ГГц на образце композиционной конструкции, изготовленной методом 3D-печати. Бердюгин А. И., Бадьин А. В., Гурский Р. П., Трофимов Е. А., Кулешов Г. Е. Терагерцовый сканирующий рефлектометр для визуализации строения полимерных конструкций в аддитивном производстве. Ural Radio Engineering Journal. 2021;5(3):207–224. DOI: 10.15826/urej.2021.5.3.001.

The JAK/STAT3 Pathway Is a Common Inducer of Astrocyte Reactivity in Alzheimer's and Huntington's Diseases.

Astrocyte reactivity is a hallmark of neurodegenerative diseases (ND), but its effects on disease outcomes remain highly debated. Elucidation of the signaling cascades inducing reactivity in astrocytes during ND would help characterize the function of these cells and identify novel molecular targets to modulate disease progression. The Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway is associated with reactive astrocytes in models of acute injury, but it is unknown whether this pathway is directly responsible for astrocyte reactivity in progressive pathological conditions such as ND. In this study, we examined whether the JAK/STAT3 pathway promotes astrocyte reactivity in several animal models of ND. The JAK/STAT3 pathway was activated in reactive astrocytes in two transgenic mouse models of Alzheimer's disease and in a mouse and a nonhuman primate lentiviral vector-based model of Huntington's disease (HD). To determine whether this cascade was instrumental for astrocyte reactivity, we used a lentiviral vector that specifically targets astrocytes in vivo to overexpress the endogenous inhibitor of the JAK/STAT3 pathway [suppressor of cytokine signaling 3 (SOCS3)]. SOCS3 significantly inhibited this pathway in astrocytes, prevented astrocyte reactivity, and decreased microglial activation in models of both diseases. Inhibition of the JAK/STAT3 pathway within reactive astrocytes also increased the number of huntingtin aggregates, a neuropathological hallmark of HD, but did not influence neuronal death. Our data demonstrate that the JAK/STAT3 pathway is a common mediator of astrocyte reactivity that is highly conserved between disease states, species, and brain regions. This universal signaling cascade represents a potent target to study the role of reactive astrocytes in ND

A practical indicator for surface ocean heat and freshwater buoyancy fluxes and its application to the NCEP reanalysis data

The buoyancy flux at the air/sea interface plays a key role in water mass transformation and mixing as it modifies surface water density and in turn drives overturning and enhances stratification. It is the interplay of these two independent heat and freshwater buoyancy flux components that is of central importance when analysing mechanisms of the ocean/atmosphere interaction. Here, a diagnostic quantity (ΘB) is presented that allows to capture the relative contribution of both components on the buoyancy flux in one single quantity. Using NCEP reanalysis of heat and freshwater fluxes (1948–2009) demonstrates that ΘB is a convenient tool to analyse both the temporal and spatial variability of their corresponding buoyancy fluxes. For the global ocean the areal extent of buoyancy gain and loss regions changed by 10%, with the largest extent of buoyancy gain during the 1970–1990 period. In the subpolar North Atlantic, and likewise in the South Pacific, decadal variability in freshwater flux is pronounced and, for the latter region, takes control over the total buoyancy flux since the 1980s. Some of the areal extent time series show a significant correlation with large-scale climate indices