Delayed loss of stability and excitation of oscillations in nonautonomous differential equations with retarded argument

Assume that zero is a stable equilibrium of an ODE ẋ = ƒ(푥, λ) for parameter values λ λ0. If we suppose that λ(t) varies slowly with t, then, under some conditions, the trajectories of the nonautonomous ODE ẋ = ƒ(푥, λ (t)) stay close to zero even long after λ(t) has crossed the value λ0. This phenomenon is called νdelayed loss of stabilityν and is well-known for ODEs. In this paper, we describe an analogous phenomenon for delay equations of the form ẋ(t) = ƒ(t, 푥 (t-1)). Further, we point out a difference between delay equations and ODEs: The inhomogeneity 풽 in the linear equation ẋ (t) = c푥 (t-1) + 풽(t) inevitably leads to an excitation of the most unstable modes of oscillation of the homogeneous equation, even if all segments 풽t are contained in a space of more rapidly decaying solutions for the homogeneous equation

Dzyaloshinskii-Moriya interaction and Hall effects in the skyrmion phase of MnFeGe alloys

We carry out density functional theory calculations which demonstrate that the electron dynamics in the skyrmion phase of Fe-rich Mn$_{1-x}$Fe$_x$Ge alloys is governed by Berry phase physics. We observe that the magnitude of the Dzyaloshinskii-Moriya interaction, directly related to the mixed space-momentum Berry phases, changes sign and magnitude with concentration $x$ in direct correlation with the data of Shibata {\it et al.}, Nature Nanotech. {\bf 8}, 723 (2013). The computed anomalous and topological Hall effects in FeGe are also in good agreement with available experiments. We further develop a simple tight-binding model able to explain these findings. Finally, we show that the adiabatic Berry phase picture is violated in the Mn-rich limit of the alloys.Comment: 5 page

Efeito do floroglucinol na reação morfogênica in vitro de segmentos internodais de Citrus sinensis (Linn.) Osbeck cv. Pêra.

Conduziu-se este trabalho em condicoes controladas de laboratorios, com o objetivo de avaliar os efeitos do floroglucinol, em diferentes niveis, sobre a reacao morfologica in vitro de segmentos internodais, casca e cilindro central de Citrus sinensis (Linn.) Osbeck cv. Pera. Utilizou-se, para multiplicacao, o meio basico de MS Semi-solido com complementos organicos em mg L-1: mio-inositol 100, sacarose 30.000, extrato de malte 500, BAP (6-benzilaminopurina) 0,3 e floroglucinol em niveis 0, 30, 60, 90 e 120 incubados no escuro, por quatro semanas, e mais quatro semanas, sob luz com fotoperiodo de 16 horas. Brotacoes adventicias obtidas do explante casca foram submetidas ao enraizamento em meio semi-solido MS com os complementos organicos em mg L-1: mio-inositol 55, sacarose 87,600, ANA (acido x-naftalenoacetico) 0,09. O delineamento experimental foi inteiramente casualizado com cinco repeticoes, considerando-se, em cada uma, a media de quatro tubos de ensaio. Nas avaliacoes morfogenicas, observou-se que nos explantes casca nao ocorreu influencia sobre o percentual de culturas calejadas e com gemas adventicias, bem como comprimento das brotacoes adventicias, o mesmo nao ocorrendo com as caracteristicas numero de brotacoes adventicias por explante e percentagem de brotacoes enraizadas, que apresentaram reducao e aumento linear, respectivamente, nos explantes do cilindro central, nao houve influencia sobre o percentual de culturas calejadas e com gemas adventicias

Uso das várzeas úmidas (brejos) e aspectos pedosociais: estudo de caso em Cajuri - MG.

Este trabalho teve por objetivo levantar, parcialmente, o conhecimento dos agricultores relativo às suas práticas agrícolas na bacia do córrego da Capivara dos Gomes com vista a compreender o sistema de uso das várzeas, também conhecidas como brejos ou leito maior, bem como, de outros recursos naturais de suas propriedades. Para isso realizaram-se treze entrevistas informais com os agricultores. Os resultados parciais das entrevistas foram agrupados por tema e buscou-se interpretar as principais afirmações ou frases mencionadas pelos agricultores. Foram, ainda, descritos e analisados (análises físicas e químicas) quatro perfis de solos localizados na várzea e na sua margem (Terraço). Como resultados foi possível observar que os agricultores demonstram pouco otimismo em relação as atividades agrícolas, achando-as cansativas e não compensatórias e há criticas ao sistema de financiamento e a metodologia de assistência técnica. Percebeu-se que possuem conhecimento empírico em razão do maior contato com a natureza e da sua maior dependência em relação aos fatores naturais e que este conhecimento podem contribuir para o melhor uso e manejo do solo. Tanto os solos da várzea quanto o do Terraço são pobres em nutrientes, o que dificulta a obtenção de maiores produtividades. Um novo modelo de uso da terra e de assistência técnica devem ser procurados uma vez que o empregado já exauriu ou não trás mais resultados satisfatórios, embora nem sempre deixem claro isto nas suas palavras. O biorregionalismo e a agroecologia podem ser caminhos promissores

Story Telling and Truth-Telling: Personal Reflections on the Native American Experience in Law Schools

In January of 2021, the American Association of Law Schools (“AALS”) theme was Freedom, Equality and the Common Good. The Indian Nations and Indigenous Peoples Section of the AALS embraced the theme and announced a call for personal reflections incorporating the experiences of Native Americans in law schools. The theme of striving for academic freedom and equality allows for an in-depth questioning of whether Native Americans have been adequately and appropriately represented in legal curricula in the nation’s approximately two hundred law schools. The aspirational goal of realizing the common good must be inclusive of Native American voices as students, faculty, staff, and graduates and in curricula choices in law schools across the country. There has been sparse legal scholarship on the experience of Native American applicants, law students, faculty, and staff in law schools. The Indigenous perspective essays in this compilation are an opportunity to hear the voices of Indigenous peoples on their lived experiences in seeking law degrees and careers in law-related fields. Words such as resiliency, endurance, and perseverance often come to mind when Native Americans discuss their personal experiences in the legal academy. The following collection of essays are a contribution to the legal academy in the Indigenous tradition of storytelling shared as firsthand accounts through the seven authors’ perspectives. Within the personal reflections, the tenacity of Native people to succeed and overcome barriers is a common theme. Many of the contributors speak to the value of mentoring or becoming a Native lawyer to serve as a mentor. The compilation provides insight into the experience the authors share of a deep commitment to their Indigenous communities and to trailblazing for the next generation of Native lawyers

Ageing enhances cellular immunity to myeloperoxidase and experimental anti-myeloperoxidase glomerulonephritis

OBJECTIVES: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune disease characterised by small blood vessel inflammation, commonly affecting the kidneys and respiratory tract. It is unclear why the incidence of this condition increases with age. Previous studies in a passive antibody transfer system in aged mice have implicated innate effectors. To test the hypothesis that autoimmunity to myeloperoxidase, an autoantigen responsible for ANCA-associated vasculitis, increases with age, anti-myeloperoxidase autoimmunity was studied in murine models of active autoimmunity and disease induced by cellular immunity. METHODS: Young (8 weeks) and aged (either 15 or 22 month) mice were immunised with whole proteins or peptides from ovalbumin, as a model foreign antigen, or myeloperoxidase protein or peptides. Mice were subjected to a model of active anti-myeloperoxidase glomerulonephritis. Cellular and humoral immune responses and tissue inflammation were assessed. RESULTS: While cellular immunity to ovalbumin was diminished in aged mice, cellular autoimmunity to myeloperoxidase and its immunodominant CD4+ and CD8+ T cell epitopes was increased after immunization with either MPO peptides or whole MPO protein, assessed by peptide and antigen specific production of the pro-inflammatory cytokines interferon-γ and interleukin-17A. MPO-ANCA titres were not increased in aged mice compared with young mice. In experimental anti-MPO glomerulonephritis, cell mediated injury was increased, likely due to CD4+ and CD8+ T cells, innate immunity and the increased vulnerability of aged kidneys. CONCLUSION: Heightened cellular immunity to MPO develops with ageing in mice and may contribute to the increased incidence and severity of ANCA-associated vasculitis in older people

The distribution of selected localized alien plant species in Hawai'i Volcanoes National Park

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.Prior to this study, the alien plant control program at Hawai'i Volcanoes National Park was hampered by the paucity and quality of alien plant distribution maps. A systematic program to map important localized alien plants was conducted 1983-1985 to determine the need and feasibility of controlling key alien plant species, establish a baseline for assessing the spread of these species, infer range expansions, locate all populations of a target species to assure thorough treatment, and assess the effectiveness of control programs. Thirty-six species were mapped, with emphasis given to localized alien plant species and those listed as target species in the 1982 Resources Management Plan (National Park Service 1982). The studies focused on Ainahou Ranch, Kilauea Crater, and the Coastal Lowlands west of the 1%9-1974 Mauna Ulu flows. The species distributions were mapped on topographic maps at 1:24,000, 1:12,000, or 1:6,000 scales, although most species are displayed in this report on smaller scale maps. In addition, species profiles are provided. These characterize importance to management, significance as a pest in native ecosystems, effective treatment methods, and history of management. There were two important findings from the distribution studies. Eleven species, previously not targeted for management, were identified from mapping efforts to be invasive and require control efforts. These are Formosan koa, slash pine, loquat, sisal, orange pittosporum, oleaster, English ivy, paperbark, blackwood acacia, kudzu, and guavasteen. The second finding is that five target species were found to be much more widespread than previously thought. These include silky oak, koa haole, fountain grass, Russian olive, and raspberry. This finding lead to an approach in which control efforts on widespread species were carried out only in intensive management units called Special Ecological Areas. Additional distribution mapping studies are recommended for widespread species.National Park Service Contract No. CA 8004 2 000