Cambio climático y anfibios

Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines in abundance have not been demonstrated. Analyses of existing data have generally failed to find a link between climate and amphibian declines. It is likely, however, that future climate change will cause further declines of some amphibian species. Reduced soil moisture could reduce prey species and eliminate habitat. Reduced snowfall and increased summer evaporation could have dramatic effects on the duration or occurrence of seasonal wetlands, which are primary habitat for many species of amphibians. Climate change may be a relatively minor cause of current amphibian declines, but it may be the biggest future challenge to the persistence of many species.Las historias vitales de los anfibios son sumamente sensibles a la temperatura y a la precipitación, y hay una clara evidencia que el reciente cambio climático ha tenido como resultado para algunas especies una anticipación del periodo de cría a lo largo del año. También se cree que el aumento reciente en la ocurrencia de fenómenos de El Niño ha causado el descenso de anuros en América Central y está relacionado con la mortalidad elevada de embriones de anfibios en el noroeste de los Estados Unidos. Sin embargo, la evidencia que relaciona el descenso de anfibios en América Central con el clima está basado únicamente en correlaciones, y no se entienden los mecanismos fundamentales que provocan este descenso. No se han podido demostrar las conexiones entre la mortalidad de embriones y el descenso de abundancia. El análisis de los datos generalmente falla a la hora de encontrar una conexión entre descensos de anfibios y el clima. Es probable, sin embargo, que posteriores cambios climáticos puedan causar descensos adicionales de algunas especies de anfibios. La humedad reducida de la tierra podría reducir las especies presa y eliminar el habitat. La reducción de nevadas invernales y el incremento de la evaporación en verano podrían tener efectos dramáticos en la duración u ocurrencia de pantanos estacionales, que es el habitat principal para muchas especies de anfibios. El cambio del clima puede ser una causa relativamente secundaria de los descensos actuales de anfibios, pero en el futuro puede ser el desafío más grande a la persistencia de muchas especies

Should the Best Offense Ever Be a Good Defense?

The Chairman of the Joint Chiefs of Staff\u27s Standing Rules of Engagement/Standing Rules for the Use of Force (SROE/SRUF) for U.S. Forces provides strategic guidance to the armed forces on the authority to use force during all military operations. The standing self-defense rules in the SROE for national, unit, and individual self-defense form the core of these use-of-force authorities. The SROE self-defense rules are incorrectly built on a unitary jus ad bellum framework, legally inapplicable below the level of national self-defense. Coupled with the pressures of sustained counter-insurgency operations, this misalignment of individual and unit self-defense authorities has led to a conflation of self-defense principles and offensive targeting authorities under the Law of Armed Conflict. In order to reverse this trend and realign individual and unit self-defense with governing legal frameworks, this Article considers self-defense through the lens of the public authority justification to better reflect the status of service members as state actors whose actions are subject to the domestic and international legal obligations of the state

Radiation Oncology at Thomas Jefferson University: A Specialty Emerges as a Department Evolves

Jefferson Radiation Oncology has maintained over fifty years of excellence led by only four chairmen. Dr Kramer after receiving his medical training inLondonled the department into the modern megavoltage era while creating the first independent academic radiation oncology department in the country. He was well-respected nationally as a leader and advocate for the specialty and he mastered the execution of progressive ideas that have raised the standard for the profession. The creation of the Radiation Therapy Oncology Group (RTOG) was critical in developing trials to expand the management and treatment of malignancy. The Patterns of Care Study (PCS) educated the masses on providing optimal care to patients by comparing strategies for the management and treatment of carcinoma through surveys across theUnited States. Dr Mansfield expanded his mentor’s vision and together they developed the Bodine Centre for Cancer Treatment, a new state-of-the-art building for cancer treatment. He helped to dispel common misconceptions, thus raising the social consciousness for managing and treating the underserved community. Dr Curran grew the RTOG to new levels in trial development, funding, and respect both domestically and internationally. He helped develop new technology in the department and markedly expanded the Jefferson Cancer Network. Finally, Dr Dicker set a new course for the department with biologically-driven radiation therapy keepingJeffersonat the forefront of new technology for the diagnosis and treatment of malignancy

An Ecological Basis for Ecosystem Management

This report was prepared by the Southwestern Regional Ecosystem Management Study Team composed of management and research biologists. The USDA Forest Service Southwestern Regions Regional Forester, Larry Henson, and the Rocky Mountain Forest and Range Experiment Station Director, Denver Burns, chartered this team to recommend an ecological basis for ecosystem management. This report is not intended to provide details on all aspects of ecosystem management; it simply provides information and makes recommendations for an ecological basis for ecosystem management. The report is not a decision document. It does not allocate resources on public lands nor does it make recommendations to that effect. The report of this Study Team may be relied upon as input in processes initiated under the National Environmental Policy Act (NEPA), National Forest Management Act (NFMA), Endangered Species Act (ESA), Administrative Procedures Act (APA), and other applicable laws. The information contained in this report is general in nature, rather than site specific. Implementation of ecosystem management and allocation of resources on Forest Service administered lands is the responsibility of the National Forest System in partnership with Forest Service Research and State and Private Forestry. Implementation is done through Forest and project plans that are subject to the NEPA process of disclosing the effects of proposed actions and affording the opportunity for public comment. The Southwestern Region follows a planning process for projects called Integrated Resource Management (IRM). The opinions expressed by the authors do not necessarily represent the policy or position of the U.S. Department of Agriculture, the Forest Service, The Nature Conservancy, or the Arizona Game and Fish Department. The Study Team acknowledges the valuable input of more than 50 individuals from various agencies, universities, professional organizations, and other groups who provided thoughtful comments of an earlier draft of this document. Some of their comments are included in Appendix 3

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms

DC-electric-field-induced and low-frequency electromodulation second-harmonic generation spectroscopy of Si(001)-SiO2_2 interfaces

The mechanism of DC-Electric-Field-Induced Second-Harmonic (EFISH) generation at weakly nonlinear buried Si(001)-SiO$_2$ interfaces is studied experimentally in planar Si(001)-SiO$_2$-Cr MOS structures by optical second-harmonic generation (SHG) spectroscopy with a tunable Ti:sapphire femtosecond laser. The spectral dependence of the EFISH contribution near the direct two-photon $E_1$ transition of silicon is extracted. A systematic phenomenological model of the EFISH phenomenon, including a detailed description of the space charge region (SCR) at the semiconductor-dielectric interface in accumulation, depletion, and inversion regimes, has been developed. The influence of surface quantization effects, interface states, charge traps in the oxide layer, doping concentration and oxide thickness on nonlocal screening of the DC-electric field and on breaking of inversion symmetry in the SCR is considered. The model describes EFISH generation in the SCR using a Green function formalism which takes into account all retardation and absorption effects of the fundamental and second harmonic (SH) waves, optical interference between field-dependent and field-independent contributions to the SH field and multiple reflection interference in the SiO$_2$ layer. Good agreement between the phenomenological model and our recent and new EFISH spectroscopic results is demonstrated. Finally, low-frequency electromodulated EFISH is demonstrated as a useful differential spectroscopic technique for studies of the Si-SiO$_2$ interface in silicon-based MOS structures.Comment: 31 pages, 14 figures, 1 table, figures are also available at http://kali.ilc.msu.su/articles/50/efish.ht

Estimated Ultraviolet Radiation Doses in Wetlands in Six National Parks

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/ Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m-2 (range of 3.4–32.1 W-h m-2). The mean dose was lowest in Acadia (13.7 W-h m-2) and highest in Rocky (24.4 W-h m-2). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 µW cm-2 (range 21.4–194.7 µW cm)2) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L-1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms

The Web will kill them all: new media, digital utopia, and political struggle in the Italian 5-Star Movement

This article examines the role of discourses about new media technology and the Web in the rise of the 5-Star Movement (Movimento 5 Stelle, or M5S) in Italy. Founded by comedian and activist Beppe Grillo and Web entrepreneur Gianrobe rto Casaleggio in 2009, this movement succeeded in becoming the second largest party at t he 2013 national elections in Italy. This article aims to discuss how elements of digital uto pia and Web-centric discourses have been inserted into the movement’s political message, and how the construction of the Web as a myth has shaped the movement’s discourse and political p ractice. The 5-Star Movement is compared and contrasted with other social and political move ments in Western countries which have displayed a similar emphasis on new media, such as the Occupy movement, the Indignados movement, and the Pirate Parties in Sweden and Germ any. By adopting and mutating cyber- utopian discourses from the so-called Californian i deology, the movement symbolically identifies itself with the Web. The traditional political esta blishment is associated with “old” media (television, radio, and the printed press), and rep resented as a “walking dead,” doomed to be superseded and buried by a Web-based direct democra cy