Benchmarking a Light-Curve Model at Low-z

A set of well-measured, {low-z}, type Ia supernovae from the Calán/Tololo SNe data sets is used to determine benchmark parameters in our hydrodynamics-based, light-curve model. The light-curve data fit fairly well in B, V, and R passbands but not as well in the I passband. The fitting procedure, extracted best-fit model parameters, and their connection to type Ia SN parameters are presented. Our benchmarked light-curve model represents an alternative to empirical template methods for the analysis of light-curve data.     

Acceleration of black hole universe

Recently, Zhang slightly modified the standard big bang theory and developed a new cosmological model called black hole universe, which is consistent with Mach’s principle, governed by Einstein’s general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This paper investigates acceleration of the black hole universe and provides an alternative explanation for the redshift and luminosity distance measurements of type Ia supernovae. The results indicate that the black hole universe accelerates its expansion when it accretes the ambient matter in an increasing rate. In other words, i.e., when the second-order derivative of the mass of the black hole universe with respect to the time is positive $\ddot{M}(t) > 0$ . For a constant deceleration parameter $q = -M(t) \ddot{M}(t)/\dot{M}(t) \sim-0.6$ , we can perfectly explain the type Ia supernova measurements with the reduced chi-square to be very close to unity, χ _red～1.0012. The expansion and acceleration of black hole universe are driven by external energy.     

Developing Courses in Applied Geography for Transportation Planners

From the demand-side, the clients and the student practitioner, TARP was a success. Although some students were not overly enthusiastic, they were exposed to a large set of new ideas and presented new skills to equip them in the transition to multimodal transportation. Local Caltrans directors were pleased with TARP. From the supply side, JCTS, the faculty, and the CSUC Consortium, TARP was a partial success. The positive elements accruing to the faculty have been mentioned. Some of the negative elements of TARP such as high initial cost occurred because of the innovative nature and the grand scale of the program. The pool of potential faculty was probably too small to permit the degree of course specialization planned for in all five locations and given the decentralized approach. Three locations would have been better from the supply-side point of view. While certain difficulties remain with such educational programs in areas of identification of clients and their needs in planning, marketing, and teaching, a rich harvest of knowledge and rapport can accrue. Returned research dollars from agencies, interdisciplinary cooperation among professors, sharing of data and equipment by agencies for student theses and, in general, a larger role for geography programs in the state and local regions are recognized as benefits. Certain geography programs that have the required expertise to initiate such applied geographic educational efforts on a more modest scale must be prepared to take the plunge. They offer a unique perspective.     

Reflections on the history of research on large wood in rivers

Dynamics and functions of large wood have become integral considerations in the science and management of river systems. Study of large wood in rivers took place as monitoring of fish response to wooden structures placed in rivers in the central United States in the early 20th century, but did not begin in earnest until the 1970s. Research has increased in intensity and thematic scope ever since. A wide range of factors has prompted these research efforts, including basic understanding of stream systems, protection and restoration of aquatic ecosystems, and environmental hazards in mountain environments. Research and management have adopted perspectives from ecology, geomorphology, and engineering, using observational, experimental, and modelling approaches. Important advances have been made where practical information needs converge with institutional and science leadership capacities to undertake multi-pronged research programmes. Case studies include ecosystem research to inform regulations for forest management; storage and transport of large wood as a component in global carbon dynamics; and the role of wood transport in environmental hazards in mountain regions, including areas affected by severe landscape disturbances, such as volcanic eruptions. As the field of research has advanced, influences of large wood on river structures and processes have been merged with understanding of streamflow and sediment regimes, so river form and function are now viewed as involving the tripartite system of water, sediment, and wood. A growing community of researchers and river managers is extending understanding of large wood in rivers to climatic, forest, landform, and social contexts not previously investigated. © 2020 John Wiley & Sons, Ltd.     

Evaluation of riverbed magnetic susceptibility for mapping biogeochemical hot spots in groundwater-impacted rivers

Redox hot spots occurring as metal-rich anoxic groundwater discharges through oxic wetland and river sediments commonly result in the formation of iron (Fe) oxide precipitates. These redox-sensitive precipitates influence the release of nutrients and metals to surface water and can act as ‘contaminant sponges’ by absorbing toxic compounds. We explore the feasibility of a non-invasive, high-resolution magnetic susceptibility (MS) technique to efficiently map the spatial variations of magnetic Fe oxide precipitates in the shallow bed of three rivers impacted by anoxic groundwater discharge. Laboratory analyses on Mashpee River (MA, USA) sediments demonstrate the sensitivity of MS to sediment Fe concentrations. Field surveys in the Mashpee and Quashnet rivers (MA, USA) reveal several discrete high MS zones, which are associated with likely anoxic groundwater discharge as evaluated by riverbed temperature, vertical head gradient, and groundwater chemistry measurements. In the East River (CO, USA), widespread cobbles/rocks exhibit high background MS from geological ferrimagnetic minerals, thereby obscuring the relatively small enhancement of MS from groundwater induced Fe oxide precipitates. Our study suggests that, in settings with low geological sources of magnetic minerals such as lowland rivers and wetlands, MS may serve as a complementary tool to temperature methods for efficiently mapping Fe oxide accumulation zones due to anoxic groundwater discharges that may function as biogeochemical hot spots and water quality control points in gaining systems.