60,000 year climate and vegetation history of Southeast Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2017Sedimentological and palynological analyses of lacustrine cores from Baker Island, located in Southeast Alaska's Alexander Archipelago, indicate that glaciers persisted on the island until ~14,500 cal yr. BP. However, the appearance of tree pollen, including Pinus cf. contorta ssp. contorta (shore pine) and Tsuga mertensiana (mountain hemlock) immediately following deglaciation suggests that a forest refugium may have been present on ice-free portions of neighboring islands or the adjacent continental shelf. Sedimentological and palynological analyses indicate a variable climate during the Younger Dryas interval between ~13,000 and ~11,500 cal yr. BP, with a cold and dry onset followed by ameliorating conditions during the latter half of the interval. An eight cm-thick black tephra dated to 13,500 ± 250 cal yr. BP is geochemically distinct from the Mt. Edgecumbe tephra and thus derived from a different volcano. Based on overall thickness, multiple normally graded beds, and grain size, I infer that the black tephra was emplaced by a large strombolian-style paroxysm. Because the dominant wind direction along this coast is from the west, the Addington Volcanic Field on the continental shelf, which would have been subaerially exposed during the eruption, is a potential source. The similarity in timing between this eruption and the Mt. Edgecumbe eruption suggests a shared trigger, possibly a response to unloading as the Cordilleran Ice Sheet retreated. To complement the Baker Island lacustrine record, a speleothem paleoclimate record based on δ¹³C and δ¹⁸O values spanning the interval from ~60,000 yr. BP to ~11,150 yr. BP was recovered from El Capitan Cave on neighboring Prince of Wales Island. More negative δ¹³C values are attributed to predominance of angiosperms in the vegetation above the cave at ~22,000 yr. BP and between ~53,000 and ~46,000 yr. BP while more positive δ¹³C values in speleothem EC-16-5-F indicate the presence of gymnosperms. These data suggest limited or no ice cover above El Capitan Cave for the duration of the record, possibly indicating that this region was a nunatak during glacial periods

Time evolution, cyclic solutions and geometric phases for the generalized time-dependent harmonic oscillator

The generalized time-dependent harmonic oscillator is studied. Though several approaches to the solution of this model have been available, yet a new approach is presented here, which is very suitable for the study of cyclic solutions and geometric phases. In this approach, finding the time evolution operator for the Schr\"odinger equation is reduced to solving an ordinary differential equation for a c-number vector which moves on a hyperboloid in a three-dimensional space. Cyclic solutions do not exist for all time intervals. A necessary and sufficient condition for the existence of cyclic solutions is given. There may exist some particular time interval in which all solutions with definite parity, or even all solutions, are cyclic. Criterions for the appearance of such cases are given. The known relation that the nonadiabatic geometric phase for a cyclic solution is proportional to the classical Hannay angle is reestablished. However, this is valid only for special cyclic solutions. For more general ones, the nonadiabatic geometric phase may contain an extra term. Several cases with relatively simple Hamiltonians are solved and discussed in detail. Cyclic solutions exist in most cases. The pattern of the motion, say, finite or infinite, can not be simply determined by the nature of the Hamiltonian (elliptic or hyperbolic, etc.). For a Hamiltonian with a definite nature, the motion can changes from one pattern to another, that is, some kind of phase transition may occur, if some parameter in the Hamiltonian goes through some critical value.Comment: revtex4, 28 pages, no figur

Acute Renal Failure in Association with Community-Acquired Clostridium difficile Infection and McKittrick-Wheelock Syndrome

We report the case of a 65-year-old Caucasian woman who experienced two separate episodes of acute renal failure within an 18-month period, both requiring emergency admission and complicated treatment. Each episode was precipitated by hypovolaemia from intestinal fluid losses, but from two rare and independent pathologies. Her first admission was attributed to community-acquired Clostridium difficile-associated diarrhoea (CDAD) and was treated in the intensive therapy unit. She returned 18 months later with volume depletion and electrolyte disturbances, but on this occasion a giant hypersecretory villous adenoma of the rectum (McKittrick-Wheelock syndrome) was diagnosed following initial abnormal findings on digital rectal examination by a junior physician. Unlike hospital-acquired C. difficile, community-acquired infection is not common, although increasing numbers are being reported. Whilst community-acquired CDAD can be severe, it rarely causes acute renal failure. This case report highlights the pathological mechanisms whereby C. difficile toxin and hypersecretory villous adenoma of the rectum can predispose to acute renal failure, as well as the values of thorough clinical examination in the emergency room, and early communication with intensivist colleagues in dire situations

Understanding social housing tenants' rent payment behaviour: evidence from Great Britain

The Governments of many Western countries have been increasingly concerned with influencing the behaviour of their citizens. One way that they have done this is by giving them new responsibilities. In the UK, an example of this is 'direct payment' which sees social housing tenants in receipt of income-related housing allowance ('Housing Benefit') assuming responsibility for paying their rent. Drawing on a comprehensive data-set generated by the direct payment pilot evaluation, this paper examines tenants' rent payment behaviour. It draws on a conceptual framework from behavioural science - COM-B - which presents behaviour (B) as a result of the interaction between the capabilities (C) of subjects, the opportunity (O) they have to enact behaviours, and their motivation (M). Tenants' behaviour was influenced by all elements of the model, with it being more than just a consequence of opportunity, and their financial circumstances, specifically, although it was the most important one

Compendium of Single Event Effects for Candidate Spacecraft Electronics for NASA

We present the results of single events effects (SEE) testing and analysis investigating the effects of radiation on electronics

International Veterinary Epilepsy Task Force Consensus Proposal: Outcome of therapeutic interventions in canine and feline epilepsy

Common criteria for the diagnosis of drug resistance and the assessment of outcome are needed urgently as a prerequisite for standardized evaluation and reporting of individual therapeutic responses in canine epilepsy. Thus, we provide a proposal for the definition of drug resistance and partial therapeutic success in canine patients with epilepsy. This consensus statement also suggests a list of factors and aspects of outcome, which should be considered in addition to the impact on seizures. Moreover, these expert recommendations discuss criteria which determine the validity and informative value of a therapeutic trial in an individual patient and also suggest the application of individual outcome criteria. Agreement on common guidelines does not only render a basis for future optimization of individual patient management, but is also a presupposition for the design and implementation of clinical studies with highly standardized inclusion and exclusion criteria. Respective standardization will improve the comparability of findings from different studies and renders an improved basis for multicenter studies. Therefore, this proposal provides an in-depth discussion of the implications of outcome criteria for clinical studies. In particular ethical aspects and the different options for study design and application of individual patient-centered outcome criteria are considered

Challenges in quantifying changes in the global water cycle

Human influences have likely already impacted the large-scale water cycle but natural variability and observational uncertainty are substantial. It is essential to maintain and improve observational capabilities to better characterize changes. Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes