Rewilding The Great Plains

This long-form journalistic story and photo essay is about Tribes in Eastern Montana and their efforts to restore native species to the Great Plains ecosystem. Across the Great Plains, Tribes are working to bring native species back to their ancestral territories. The swift fox, black-footed ferret and buffalo were all pushed to the brink of extinction as colonizers took over. Now, Tribes on Fort Peck, Northern Cheyenne and Fort Belknap are partnering with conservation organizations to help repair the prairie ecosystem. Driven by cultural knowledge and a sense of responsibility, many Tribes are learning from past mistakes and nearby successes. Great Plains Indians are working to keep an important connection to their past while simultaneously protecting the land for future generations. The Great Plains are a part of the most endangered biome in the world. Centuries of agricultural expansion has created an inhospitable environment with little biodiversity. Wildlife is a fundamental aspect of any ecosystem, and buffalo and prairie dogs are the keystone species on the prairie. Without them the habitat cannot exist as it is. Swift fox and black-footed ferrets are not considered keystone species, but they are important indicators of grassland health. All these animals are important components of the Great Plains ecosystem. And these species cannot live in another habitat. The goal of these reintroductions is to protect an important ecosystem and save multiple species from extinction. For Tribal members there is the added importance of preserving ancestral knowledge and maintaining a connection to their culture. Each Tribe has a different cultural connection to the land and its inhabitants, but the respect is common across the Tribes

A white dwarf-neutron star relativistic binary model for soft gamma-ray repeaters

A scenario for SGRs is introduced in which gravitational radiation reaction effects drive the dynamics of an ultrashort orbital period X-ray binary embracing a high-mass donor white dwarf (WD) to a rapidly rotating low magnetised massive neutron star (NS) surrounded by a thick, dense and massive accretion torus. Driven by GR reaction, sparsely, the binary separation reduces, the WD overflows its Roche lobe and the mass transfer drives unstable the accretion disk around the NS. As the binary circular orbital period is a multiple integer number ($m$) of the period of the WD fundamental mode (Pons et al. 2002), the WD is since long pulsating at its fundamental mode; and most of its harmonics, due to the tidal interaction with its NS orbital companion. Hence, when the powerful irradiation glows onto the WD; from the fireball ejected as part of the disk matter slumps onto the NS, it is partially absorbed. This huge energy excites other WD radial ($p$-mode) pulsations (Podsiadlowski 1991,1995). After each mass-transfer episode the binary separation (and orbital period) is augmented significantly (Deloye & Bildsten 2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum redistribution. Thus a new adiabatic inspiral phase driven by GR reaction starts which brings the binary close again, and the process repeats. This model allows to explain most of SGRs observational features: their recurrent activity, energetics of giant superoutbursts and quiescent stages, and particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al. 1999), which are suggested here to be {\it overtones} of the WD radial fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).Comment: This paper was submitted as a "Letter to the Editor" of MNRAS in July 17/2004. Since that time no answer or referee report was provided to the Author [MNRAS publication policy limits reviewal process no longer than one month (+/- half more) for the reviewal of this kind of submission). I hope this contribution is not receiving a similar "peer-reviewing" as given to the A. Dar and A. De Rujula's "Cannonball model for gamma-ray bursts", or to the R.K. Williams' "Penrose process for energy extraction from rotating black holes". The author welcomes criticisms and suggestions on this pape

A Robust Determination of the size of quasar accretion disks using gravitational microlensing

Using microlensing measurements from a sample of 27 image-pairs of 19 lensed quasars we determine a maximum likelihood estimate for the accretion disk size of an {{\em}average} quasar of $r_s=4.0^{+2.4}_{-3.1}$ light days at rest frame $=1736$\AA\ for microlenses with a mean mass of $=0.3M_\odot$. This value, in good agreement with previous results from smaller samples, is roughly a factor of 5 greater than the predictions of the standard thin disk model. The individual size estimates for the 19 quasars in our sample are also in excellent agreement with the results of the joint maximum likelihood analysis.Comment: 6 pages, 3 figures, submitted to Ap