1,656,383 research outputs found
The Role and Work of Bomber Command: A Note by Air Marshal Sir Arthur Harris for the Prime Minister and Cabinet, 28 June 1942
Editor’s Note: Few senior Allied Commanders have been criticized as strongly as Air Marshal Sir Arthur Harris. And even those critics who recognize the vital contribution Harris and the Bomber Command made to the defeat of Nazi Germany are disturbed by the tone of Harris’ letters to Churchill and Air Chief Marshal Sir Charles Portal. Harris never wavered in his conviction that Germany could be defeated by strategic bombing with ground roops assigned to a secondary role. This view underlay his arguments for assigning priority to strategic bombing. In pursuing the case Harris mixed careful argument and clear logic with emotional attacks on those who doubted his doctrines. The following note, written shortly after Harris assumed command, displays Harris at his best, arguing the case for Bomber Command “as the only means of bringing assitance to Russian in time” and the only means “which will make subsequent invasion a possible proposition.
Harris recurrence of Metropolis-within-Gibbs and trans-dimensional Markov chains
A -irreducible and aperiodic Markov chain with stationary probability
distribution will converge to its stationary distribution from almost all
starting points. The property of Harris recurrence allows us to replace
``almost all'' by ``all,'' which is potentially important when running Markov
chain Monte Carlo algorithms. Full-dimensional Metropolis--Hastings algorithms
are known to be Harris recurrent. In this paper, we consider conditions under
which Metropolis-within-Gibbs and trans-dimensional Markov chains are or are
not Harris recurrent. We present a simple but natural two-dimensional
counter-example showing how Harris recurrence can fail, and also a variety of
positive results which guarantee Harris recurrence. We also present some open
problems. We close with a discussion of the practical implications for MCMC
algorithms.Comment: Published at http://dx.doi.org/10.1214/105051606000000510 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
The Trichoptera of Panama XIV. New species of microcaddisflies (Trichoptera: Hydroptilidae) from Omar Torrijos Herrera National Park
Abstract. In 2017, a new project was begun to assess the biodiversity of national parks and forest reserves in the Republic of Panama. Designated “Proyecto Sistema de Producción Sostenible Conservación de la Biodiversidad (PSPSCB)”, this project is managed by Panama’s Ministerio de Ambiente. The first park sampled in 2017 was Omar Torrijos Herrera National Park (OTHNP). Trichoptera (Insecta) were collected at four locations using both Malaise traps and UV light traps. The rugged terrain and lack of access in this remote park limited the sampled area. Sampling included streams in both the Caribbean and Pacific drainages. Seven new species of microcaddisflies (Hydroptilidae: Alistotrichia coclensis Armitage and Harris, Cerasmatrichia akanthos Armitage and Harris, Metrichia corazones Armitage and Harris, Neotrichia espinosa Armitage and Harris, Neotrichia michaeli Armitage and Harris, Neotrichia pierpointorum Armitage and Harris, and Neotrichia yayas Armitage and Harris) and one new country record, Metrichia macrophallata Flint, were identified from this preliminary survey and are reported herein. Other recently described species are reported here for the first time outside of their type localities. Based on other areas more extensively sampled compared to this modest survey, many more new species and new country records await discovery in OTHNP as are reported herein. There are now 439 species distributed among 15 families and 55 genera known from Panama.
Resumen. En 2017, se inició un nuevo proyecto para evaluar la biodiversidad de parques nacionales y reservas forestales en la República de Panamá. Designado “Proyecto Sistema de Producción Sostenible Conservación de la Biodiversidad (PSPSCB)”, este proyecto es administrado por el Ministerio de Ambiente de Panamá. El primer parque muestreado en 2017 fue el Parque Nacional Omar Torrijos Herrera (OTHNP). Se recogieron Trichoptera en cuatro ubicaciones utilizando trampas Malaise y trampas de luz UV. El terreno accidentado y la falta de acceso en este parque remoto limitaron el área muestreada. El muestreo incluyó corrientes en los drenajes del Caribe y del Pacífico. Siete nuevas especies de micro-Trichoptera (Hydroptilidae: Alistotrichia coclensis Armitage and Harris, Cerasmatrichia akanthos Armitage and Harris, Metrichia corazones Armitage and Harris, Neotrichia espinosa Armitage and Harris, Neotrichia michaeli Armitage and Harris, Neotrichia pierpointorum Armitage and Harris, and Neotrichia yayas Armitage and Harris) y un nuevo registro de país, Metrichia macrophallata Flint, se identificaron a partir de esta encuesta preliminar y se informan aquí. Otras especies recientemente descritas se registran aquí por primera vez fuera de sus localidades tipo. Con base en otras áreas más extensamente muestreadas, en comparación con esta modesta investigación, muchas más especies nuevas y nuevos registros para el país esperan ser descubiertos en el OTHNP como se informa aquí. Ahora en Panamá, hay 439 especies conocidas de Trichoptera distribuidas entre 15 familias y 55 géneros
Moduli of Crude Limit Linear Series
Eisenbud and Harris introduced the theory of limit linear series, and
constructed a space parametrizing their limit linear series. Recently, Osserman
introduced a new space which compactifies the Eisenbud-Harris construction. In
the Eisenbud-Harris space, the set of refined limit linear series is always
dense on a general reducible curve. Osserman asks when the same is true for his
space. In this paper, we answer his question by characterizing the situations
when the crude limit linear series contain an open subset of his space.Comment: 13 page
A non-conservative Harris ergodic theorem
We consider non-conservative positive semigroups and obtain necessary and
sufficient conditions for uniform exponential contraction in weighted total
variation norm. This ensures the existence of Perron eigenelements and provides
quantitative estimates of the spectral gap, complementing Krein-Rutman theorems
and generalizing probabilistic approaches. The proof is based on a
non-homogenous -transform of the semigroup and the construction of Lyapunov
functions for this latter. It exploits then the classical necessary and
sufficient conditions of Harris's theorem for conservative semigroups and
recent techniques developed for the study of absorbed Markov processes. We
apply these results to population dynamics. We obtain exponential convergence
of birth and death processes conditioned on survival to their quasi-stationary
distribution, as well as estimates on exponential relaxation to stationary
profiles in growth-fragmentation PDEs
The Trichoptera of Panama XIII. Further new country records for caddisflies (Insecta: Trichoptera) from the Republic of Panama
The Republic of Panama currently includes 414 recorded species of Trichoptera. Herein we add two new genera (Hydroptilidae: Angrisanoia Ozdikmen, 2008 and Mayatrichia Mosely, 1937) and 17 new country records (Philopotamidae: Chimarra (C.) tapanti Blahnik, Wormaldia bolivari Muñoz-Quesada and Holzenthal, and Wormaldia zunigae Muñoz-Quesada and Holzenthal; Hydropsychidae: Centromacronema pygmaeum Botosaneanu; Hydroptilidae: Brysopteryx esparta Harris and Holzenthal, Byrsopteryx solisi Harris and Holzenthal, Costatrichia falsa Santos, Takiya, and Nessimian, Mayatrichia illobia Harris and Holzenthal, Metrichia amplitudinis Bueno-Soria and Holzenthal, Ochrotrichia boquillas Moulton and Harris, O. conformalis Bueno-Soria and Holzenthal, O. quinealensis Bueno-Soria and Holzenthal, and O. unica Bueno-Soria and Santiago; Leptoceridae: Triaenodes morai Holzenthal and Andersen; Odontoceridae: Marilia kingsolveri Bueno-Soria and Rojas-Ascencio; and, Helicopsychidae: Helicopsyche alajuela Johanson and Holzenthal and Helicopsyche breviterga Flint) to Panama’s caddisfly fauna. The newly recorded taxa increase Panama’s total known caddisfly fauna to 431 species, distributed among 15 families and 55 genera. These results are part of an ongoing effort to characterize the caddisfly fauna of Panama, and to evaluate the aquatic insect diversity of the country’s major watersheds (cuencas).
La República de Panamá actualmente incluye 414 especies registradas de Trichoptera. Aquí agregamos dos nuevos géneros (Hydroptilidae: Angrisanoia Ozdikmen, 2008 y Mayatrichia Mosely, 1937) y 17 nuevos registros para el país (Philopotamidae: Chimarra (C.) tapanti Blahnik, Wormaldia bolivari Muñoz-Quesada y Holzenthal, y Wormaldia zunigae Muñoz-Quesada y Holzenthal; Hydropsychidae: Centromacronema pygmaeum Botosaneanu; Hydroptilidae: Brysopteryx esparta Harris y Holzenthal, Byrsopteryx solisi Harris y Holzenthal, Costatrichia falsa Santos, Takiya, y Nessimian, Mayatrichia illobia Harris y Holzenthal, Metrichia amplitudinis Bueno-Soria y Holzenthal, Ochrotrichia boquillas Moulton y Harris, Ochrotrichia conformalis Bueno-Soria y Holzenthal, Ochrotrichia quinealensis Bueno-Soria y Holzenthal, y Ochrotrichia unica Bueno-Soria y Santiago; Leptoceridae: Triaenodes morai Holzenthal y Andersen; Odontoceridae: Marilia kingsolveri Bueno-Soria y Rojas- Ascencio; y, Helicopsychidae: Helicopsyche alajuela Johanson y Holzenthal y Helicopsyche breviterga Flint) a la fauna de Trichoptera de Panamá. Los taxones recien reportados aumentan el total de la fauna de Trichoptera de Panamá a 431 especies, distribuidas en 15 familias y 55 géneros. Estos resultados son parte de un esfuerzo continuo para caracterizar la fauna de Trichoptera y para evaluar la diversidad de insectos acuáticos de las principales cuencas hidrográficas (cuencas) de Panamá
Particle-in-cell simulations of collisionless magnetic reconnection with a non-uniform guide field
Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov–Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction and a non-uniform guide field in a second direction, resulting in a spatially constant magnetic field strength as well as a constant initial plasma density and plasma pressure. It is found that the reconnection process initially resembles guide field reconnection, but that a gradual transition to anti-parallel reconnection happens as the system evolves. The time evolution of a number of plasma parameters is investigated, and the results are compared with simulations starting from a Harris sheet equilibrium and a Harris sheet plus constant guide field equilibrium
Journal of African Christian Biography: v. 1, no. 5
A publication of the Dictionary of African Christian Biography with U.S. offices located at the Center for Global Christianity and Mission at Boston University. This issue focuses on: 1. William Wadé Harris, Prophet-Evangelist of West Africa: His Life, Message, Praxis, Heritage, and Legacy. 2. William Wadé Harris. 3. Recent Print and Digital Resources Related to Christianity in Africa
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