ABSTRACT
We propose a compact binary model with an eccentric orbit to explain periodically active fast radio burst (FRB) sources, where the system consists of a neutron star (NS) with strong dipolar ...magnetic fields and a magnetic white dwarf (WD). In our model, the WD fills its Roche lobe at periastron, and mass transfer occurs from the WD to the NS around this point. The accreted material may be fragmented into a number of parts, which arrive at the NS at different times. The fragmented magnetized material may trigger magnetic reconnection near the NS surface. The electrons can be accelerated to an ultrarelativistic speed, and therefore the curvature radiation of the electrons can account for the burst activity. In this scenario, the duty cycle of burst activity is related to the orbital period of the binary. We show that such a model may work for duty cycles roughly from 10 min to 2 d. For the recently reported 16.35-d periodicity of FRB 180916.J0158 + 65, our model does not naturally explain such a long duty cycle, since an extremely high eccentricity (e > 0.95) is required.
In his many best-selling books, Yi-Fu Tuan seizes big, metaphysical issues and considers them in uniquely accessible ways. Human Goodness is evidence of this talent and is both as simple, and as ...epic, as it sounds.             Genuinely good people and their actions, Tuan contends, are far from boring, naive, and trite; they are complex, varied, and enormously exciting. In a refreshing antidote to skeptical times, he writes of ordinary human courtesies, as simple as busing your dishes after eating, that make society functional and livable. And he writes of extraordinary courage and inventiveness under the weight of adversity and evil. He considers the impact of communal goodness over time, and his sketches of six very different individuals—Confucius, Socrates, Wolfgang Amadeus Mozart, John Keats, Dr. Albert Schweitzer, and Simone Weil—confirm that there are human lives that can encourage and lead us to our better selves.   Best Books for General Audiences, selected by the American Association of School Librarians, and Best Books for Special Interests, selected by the Public Library Association
Who Am I? is the bittersweet memoir of a Chinese American who came to this country as a twenty-year-old graduate student and stayed to become one of America's most innovative intellectuals, whose ...work has explored the aesthetic and moral dimensions of human relations with landscape, nature, and environment.
Perceptual and cultural geography: A commentary Tuan, Yi-Fu
Annals of the Association of American Geographers,
12/1/2003, 20031201, December 2003, 2003-12-00, Letnik:
93, Številka:
4
Journal Article
Recenzirano
Geographers' understanding of culture has become more psychological, following society's growing inclination to analyze itself psychologically. Tuan discusses the importance of taking into account ...individuality, noting that the basis of perceptual geography lies in the recognition of the vital nature of individual perception.
We study the prospects of searching for black hole (BH) binary systems with a stellar-mass BH and a non-compact visible companion, by utilizing the spectroscopic data of the Large Sky Area ...Multi-object Fiber Spectroscopic Telescope (LAMOST). We simulate the Galactic BH binary population and determine its optical visibility by considering the stellar synthetic population model and the distributions of binary orbital parameters. By convolving the visibility of BH binaries with the LAMOST detection sensitivity, we predict that 400 candidate BH binaries can be found by the low-resolution, non-time-domain survey, and ∼50-350 candidates by the LAMOST ongoing medium-resolution, time-domain spectroscopic survey. Most of the candidates are short-period (0.2-2 days) binaries with M-, K-, G-, or F-type companions, in which ∼47% have a mass function (the lower limit of the BH mass) larger than 3 M . By complementing the LAMOST spectroscopic data with other photometric/spectroscopic surveys or follow-up observations, these candidates could be confirmed. Therefore, by exploring the LAMOST data, we can enlarge the sample of dynamically confirmed BH binaries significantly, which can improve our understanding of the mass distribution of BHs and the stellar evolution model.
Cultural Geography: Glances Backward and Forward Tuan, Yi-Fu
Annals of the Association of American Geographers,
12/1/2004, 20041201, December 2004, 2004-12-00, Letnik:
94, Številka:
4
Journal Article
Recenzirano
The position Tuan recommends calls for a degree of disengagement from the issue and ideas of the day.
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