On Mobile Bay

https://digitalcommons.library.umaine.edu/mmb-vp/2310/thumbnail.jp

A-model and generalized Chern-Simons theory

The relation between open topological strings and Chern-Simons theory was discovered by E. Witten. He proved that A-model on T*M where M is a three-dimensional manifold is equivalent to Chern-Simons theory on M and that A-model on arbitrary Calabi-Yau 3-fold is related to Chern-Simons theory with instanton corrections. In present paper we discuss multidimensional generalization of these results.Comment: 11 pages, latex, minor change

Permafrost Degradation Leaves Us On Thin Ice

The Tanana River flows through interior Alaska, a region characterized by discontinuous permafrost. Studies link degrading permafrost to increased winter river discharge due to increasing groundwater input. In winter, interior Alaskan rivers are exclusively fed by groundwater, which serves as an external source of heat. In fact, some portions of rivers fed by groundwater maintain thin ice throughout the winter, or remain altogether ice-free, despite very cold air temperatures. These ice conditions represent a significant danger to winter travellers who use rivers for wintertime travel, particularly in this largely roadless area. We developed a physically-based, numeric model to explore how fluctuations in groundwater discharge control ice thickness on the Tanana River. The model allows us to examine how changes in groundwater flow affect ice dynamics by addressing two questions: 1) What are the dominant factors controlling seasonal ice dynamics on the Tanana River? 2) What are the rates of change in ice thickness resulting from observed and projected changes in these factors?NSF, Alaska EPSCoR, Water and Environmental Research Center, Alaska Climate Science Center, Resilience and Adaptation Progra

Modeling the Thermal Balance Between Groundwater Springs and River Ice

We modeled the thermal balance between groundwater discharge and ice-free areas in the Tanana River near Fairbanks, Alaska, a region that is characterized by discontinuous permafrost. Under degrading permafrost conditions, these areas have been hypothesized to have increased winter discharge due to increasing contributions from groundwater flow. In the winter, interior Alaskan rivers are fed almost entirely by groundwater, which also serves as an external source of heat energy to the system. Several reaches of the river fed by groundwater springs remain ice-free or have dangerously thin ice throughout the winter despite air temperatures that dip below -40° C. These areas are dangerous for winter travelers who regularly use Alaskan rivers for wintertime travel. Our model allows us to explore the relationship between seasonal groundwater flows and ice thickness under changing atmospheric conditions. Our model results explore how local and regional changes in groundwater flow can affect ice thickness by addressing two primary research questions: 1) What physical factors influence seasonal ice dynamics on the Tanana River? 2) How is the thermal balance maintained between changing groundwater flow and cold air temperatures?NSF, US Army Corps of Engineers, Alaska EPSCoR, Resilience and Adaptation Program, Water and Environment Research Center, Alaska Climate Science Cente

Using local knowledge, hydrologic, and climate data to develop a driftwood harvest model in interior Alaska

Rural Alaskan residents are concerned that the character of the summer discharge in the Yukon River is changing, which is affecting their ability to harvest driftwood. The Yukon River flows northwesterly through British Columbia and the Yukon Territory before flowing southwest through Alaska. In most summers, residents of Tanana, Alaska harvest driftwood from the Yukon River during two different periods. Typically, driftwood accompanies high flows on the Yukon River associated with spring break‐up. A few weeks later, a second series of driftwood appears, associated with the “2nd rise,” which is reported to occur during early June. This study examines the nature of the differential timing of high flow events in the Yukon River. Many communities in interior Alaska have grown to rely upon driftwood as an important source of wood, which is used in construction, carving, and as a fuel source. Increasingly, villages in rural Alaska are trying to lessen their dependence upon expensive fossil fuels. To achieve this goal, a number of Alaskan villages have recently installed wood chip‐fired boilers to generate heat and/or electricity and additional boilers are slated to be installed in rural Alaska in the near future. These boilers are largely fed by driftwood, a cheap and easily processed wood source. Some Tanana residents have expressed concern that in recent years, driftwood was not readily available because the “2nd rise” flood event was absent. This is disconcerting for rural Alaskans that are becoming increasingly reliant upon the driftwood flows. Our goal is to determine if the perceived changes in driftwood availability are related to changes in river hydrology and if predicted changes in hydrology may affect driftwood flows and the livelihoods of rural Alaskans.NSF, Resilience and Adaptation Program, Water and Environmental Research Center, Alaska EPSCoR

Using Local Knowledge, Hydrologic, and Climate Data to Develop a Driftwood Harvest Model in Interior Alaska

Many rural Alaska residents rely on harvested driftwood from the Yukon River for fuel and construction materials, however they have stated that the character of the summer discharge in the Yukon River is changing and affecting their ability to harvest this resource. We examined whether the perceived changes in driftwood availability are related to changes in river hydrology and how changes in hydrology may affect future driftwood flows and the livelihoods of rural Alaskans.IAB, NSF, RAP, WERC, Alaska APSCo

Combining isotope ratios for provenancing Viking Age iron artefacts in the British Isles: a pilot study

Stable and radiogenic isotope analysis – particularly using lead isotope analysis (LIA) - has previously been shown to be a useful tool for the provenancing of ancient metal artefacts of silver and copper and its alloys, but less progress has been made in the provenancing of iron artefacts, despite their importance and frequency in the archaeological record. In this pilot study we investigate for the first time the possibilities of iron isotope analysis in combination with trace strontium isotope analysis and LIA for the provenancing of iron objects believed to be from the Viking Age in the British Isles. Previous studies have shown that analysis of each of these isotopes can contribute to provenancing iron artefacts, but they are not individually resolutory. In this proof-of-concept study, we examine the Fe, Sr and Pb isotopes of 7 artefacts believed to derive from the Viking Age: 3 from Meols - a former Viking seaport on Wirral and 4 samples from the probable location of the AD 1066 Battle of Fulford in North Yorkshire. We also examine an additional artefact of unknown antiquity from Bebington Heath – a possible location of the AD 937 Battle of Brunanburh. Although the pilot data set is too small to make definitive conclusions, it has paved the way for a fuller study involving 100 samples (including 30 from the former Viking camp of Torksey, Lincolnshire) funded by the NEIF fund of the UK National Environmental Research Council. The high range of 87Sr/86Sr values in the present data set of 8 is beyond what would be expected for bog iron (with a cut-off ~ 0.709) and suggests that mined ore was being used, a preliminary conclusion supported by the narrow range of Fe isotope data

Do agri-environment schemes result in improved water quality?

Welsh Government. Grant Number: 183/2007/0

Campath, calcineurin inhibitor reduction and chronic allograft nephropathy (3C) study: background, rationale, and study protocol.

BACKGROUND: Kidney transplantation is the best treatment for patients with end-stage renal failure, but uncertainty remains about the best immunosuppression strategy. Long-term graft survival has not improved substantially, and one possible explanation is calcineurin inhibitor (CNI) nephrotoxicity. CNI exposure could be minimized by using more potent induction therapy or alternative maintenance therapy to remove CNIs completely. However, the safety and efficacy of such strategies are unknown. METHODS/DESIGN: The Campath, Calcineurin inhibitor reduction and Chronic allograft nephropathy (3C) Study is a multicentre, open-label, randomized controlled trial with 852 participants which is addressing two important questions in kidney transplantation. The first question is whether a Campath (alemtuzumab)-based induction therapy strategy is superior to basiliximab-based therapy, and the second is whether, from 6 months after transplantation, a sirolimus-based maintenance therapy strategy is superior to tacrolimus-based therapy. Recruitment is complete, and follow-up will continue for around 5 years post-transplant. The primary endpoint for the induction therapy comparison is biopsy-proven acute rejection by 6 months, and the primary endpoint for the maintenance therapy comparison is change in estimated glomerular filtration rate from baseline to 2 years after transplantation. The study is sponsored by the University of Oxford and endorsed by the British Transplantation Society, and 18 centers for adult kidney transplant are participating. DISCUSSION: Late graft failure is a major issue for kidney-transplant recipients. If our hypothesis that minimizing CNI exposure with Campath-based induction therapy and/or an elective conversion to sirolimus-based maintenance therapy can improve long-term graft function and survival is correct, then patients should experience better graft function for longer. A positive outcome could change clinical practice in kidney transplantation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01120028 and ISRCTN88894088.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are