Herbivores limit the population size of big-leaf mahogany trees in an Amazonian forest

The Janzen–Connell hypothesis proposes that specialized herbivores maintain high numbers of tree species in tropical forests by restricting adult recruitment so that host populations remain at low densities. We tested this prediction for the large timber tree species, Swietenia macrophylla, whose seeds and seedlings are preyed upon by small mammals and a host-specific moth caterpillar Steniscadia poliophaea, respectively. At a primary forest site, experimental seed additions to gaps – canopy-disturbed areas that enhance seedling growth into saplings – over three years revealed lower survival and seedling recruitment closer to conspecific trees and in higher basal area neighborhoods, as well as reduced subsequent seedling survival and height growth. When we included these Janzen–Connell effects in a spatially explicit individual-based population model, the caterpillar's impact was critical to limiting Swietenia's adult tree density, with a > 10-fold reduction estimated at 300 years. Our research demonstrates the crucial but oft-ignored linkage between Janzen–Connell effects on offspring and population-level consequences for a long-lived, potentially dominant tree species.

STUDY OF THE EFFECTS OF TOTAL MODULATION TRANSFER FUNCTION CHANGES ON OBSERVER PERFORMANCE USING CLINICAL MAMMOGRAMS

The main goal of this study was to relate physical changes in image quality measured by Modulation Transfer Function (MTF) to diagnostic accuracy.^ One Hundred and Fifty Kodak Min-R screen/film combination conventional craniocaudal mammograms obtained with the Pfizer Microfocus Mammographic system were selected from the files of the Department of Radiology, at M.D. Anderson Hospital and Tumor Institute.^ The mammograms included 88 cases with a variety of benign diagnosis and 62 cases with a variety of malignant biopsy diagnosis. The average age of the patient population was 55 years old. 70 cases presented calcifications with 30 cases having calcifications smaller than 0.5mm. 46 cases presented irregular bordered masses larger than 1 cm. 30 cases presented smooth bordered masses with 20 larger than 1 cm.^ Four separated copies of the original images were made each having a different change in the MTF using a defocusing technique whereby copies of the original were obtained by light exposure through different thicknesses (spacing) of transparent film base.^ The mammograms were randomized, and evaluated by three experienced mammographers for the degree of visibility of various anatomical breast structures and pathological lesions (masses and calicifications), subjective image quality, and mammographic interpretation.^ 3,000 separate evaluations were anayzed by several statistical techniques including Receiver Operating Characteristic curve analysis, McNemar test for differences between proportions and the Landis et al. method of agreement weighted kappa for ordinal categorical data.^ Results from the statistical analysis show: (1) There were no statistical significant differences in the diagnostic accuracy of the observers when diagnosing from mammograms with the same MTF. (2) There were no statistically significant differences in diagnostic accuracy for each observer when diagnosing from mammograms with the different MTF's used in the study. (3) There statistical significant differences in detail visibility between the copies and the originals. Detail visibility was better in the originals. (4) Feature interpretations were not significantly different between the originals and the copies. (5) Perception of image quality did not affect image interpretation.^ Continuation and improvement of this research ca be accomplished by: using a case population more sensitive to MTF changes, i.e., asymptomatic women with minimum breast cancer, more observers (including less experienced radiologists and experienced technologists) must collaborate in the study, and using a minimum of 200 benign and 200 malignant cases.^

Female pipefish can detect the immune status of their mates

Given the ubiquity of the parasites and their important fitness consequences on mate and offspring condition, selection for the ability to distinguish healthy from parasitized potential mates is a key process to enhance Darwinian fitness. In this study, we experimentally evaluated how the immunological experience of two potential partners influences mate choice, using the sex-role-reversed pipefish Syngnathus typhle. We exposed S. typhle to immune challenges with heat-killed Vibrio bacteria and investigated whether the activation of the immune system determined mate preferences. Our results demonstrate that the immune status of the potential partners influenced female mate preference, such that females that were exposed to an immune challenge became choosy and favored unchallenged males. Males, however, did not show any preferences for female immune status. In this context, we discuss mate choice decisions and behavioral plasticity as a complex result of immune challenge, severity of infection, as well as trans-generational effects.

La estética y narrativa del vídeo musical como representante del discurso audiovisual hipermoderno

Desde que en 1981 la cadena norteamericana de televisión por cable MTV introdujera el videoclip como elemento transgresor en el entramado televisivo, no ha existido pieza audiovisual más permeable, impactante e innovadora en la reciente historia del audiovisual. Representante vivo de la sociedad postmoderna, heredero de las vanguardias y popular herramienta publicitaria; el vídeo musical ha conseguido aquello que el cine sigue intentando instaurar: llegar al “mainstream” social inculcando premisas artísticas. Actualmente, no hay artista musical que no tenga alguna obra vídeo musical que ilustre su trabajo. Forma parte de su imagen de marca y es una herramienta de marketing indispensable. El cantante pop no solo vende su música, vende una imagen que busca identificar a un público que, en consecuencia, consumirá su música. Pero, ¿en qué medida es cuantificable el éxito del videoclip? En los albores de dicha cadena televisiva, resultaba evidente la incidencia de videoclips como Thriller (John Landis, 1983) en las ventas de discos (Pérez-Yarza, 1996, 30). Hoy en día, el vídeo musical es más una inercia empresarial cuyos costes de producción han bajado de manera considerable y su éxito se mide en número de reproducciones...

Got A Minute: Instruction Tune-Up for Time Pressed Librarians

This book contains 19 essays that have been written by current LIS Students who were enrolled in the LIS4330: Library Instruction class at the University of Denver, 2016. Designed to provide a short and pithy overview of a topic that is related to instruction, education, or information literacy, each essays aims to be accessible and approachable for time-pressed librarians who may not have time to catch up.

Report of the Emergency board to the President, appointed September 27, 1938 under Section 10 of the Railway labor act, in re Atchison, Topeka & Santa Fe railway and other class 1 railroads, common carriers engaged in interstate commerce, and certain of their employees represented by committee of eighteen cooperating labor organizations and the Brotherhood of railroad trainmen.

Dated: October 29, 1938.

Your servant the molecule /

"First printing."

Proceedings, Intermountain Forest Nursery Association : August 12-16, 1991, Park City, Utah /

"February, 1992."

Target Seedling Symposium : proceedings, combined meeting of the Western Forest Nursery Associations, August 13-17, 1990, Roseburg, Oregon /

"December, 1990."

The copperhead.

Mode of access: Internet.