Late Quaternary Vegetation Development Following Deglaciation of Northwestern Alexander Archipelago, Alaska

The Cordilleran Ice Sheet covered most of southeastern Alaska during the Last Glacial Interval (LGI: Marine Isotope Stage 2). Ice began to recede from western Alexander Archipelago ∼17,000 ± 700 yr BP. In this study, pollen analysis and radiocarbon dating of three sediment cores were used to reconstruct, for the first time, the postglacial development of vegetation in the northwestern Alexander Archipelago during the past ∼15,240 cal yr. Hummingbird Lake (HL), on southwestern Baranof Island, yielded a sediment core with one of the longest dated records from southeastern Alaska. The earliest part of the HL pollen record (∼15,240–14,040 yr BP) indicates that the earliest vegetation was pine (Pinus contorta subsp. contorta) parkland with willows (Salix), heaths (Ericaceae), sedges (Cyperaceae), grasses (Poaceae), herbs and ferns. Starting at ∼14,040 yr BP, alder (Alnus) rapidly colonized the area as pine populations declined. By 11,400 yr BP, Sitka spruce (Picea sitchensis) colonized the area, and soon became the dominant conifer. Mountain hemlock (Tsuga mertensiana) also colonized the area by ∼11,400 yr BP, followed by western hemlock (Tsuga heterophylla) at ∼10,200 yr BP. By ∼9200 yr BP, western hemlock had become the dominant tree species in the area. During the late Holocene yellow cedar (Chamaecyparis nootkatensis) became established. Two marine sediment cores were also analyzed for pollen, with the oldest core from Lower Sitka Sound, between Kruzof and Baranof Islands. The lower part of the core consists of interlayered tephras and freshwater lake muds that are estimated to be ∼14,000 to 13,150 yr BP. Pollen evidence indicates that the early postglacial vegetation around Sitka Sound was pine parkland with alders and abundant ferns. Damage to vegetation around Sitka Sound by volcanic eruptions is suggested by abrupt, large shifts in percentages of alder and pine pollen, and fern spores in samples adjacent to tephra layers. A marine sediment core from Slocum Arm, a fiord on the western coast of Chichagof Island, has a basal age of ∼10,000 yr BP. The pollen record is similar to the Holocene pollen record at Hummingbird Lake. The sequence of vegetation changes interpreted from the three northwestern Alexander Archipelago pollen records is similar to those from other well-dated sites in southeastern Alaska, although chronologies differ between sites

Late Quaternary Environmental History of the Tanana Valley, Alaska

Pollen histories from three lakes and a peat bog in the middle Tanana Valley, interior Alaska, provide a regionally-consistent record of vegetational changes spanning approximately the last 16,000 years. Lacustrine sediment cores from Birch Lake (64°19’ N Lat., 146°40’ W Long.) and Lake George (63°47’ N Lat., 144°30’ W Long.) yielded the oldest pollen records yet obtained from interior Alaskan lakes. Pollen spectra from the basal sections of these cores are assigned to Pollen Zone 1, and they are characterized by high percentages (20-50%) of both grass and sage (Artemisia) pollen, and lower but significant amounts of sedge and willow pollen. Zone 1 pollen spectra contain only a few percent of pollen of spruce, birch, and alder. The vegetation that produced Zone 1 pollen spectra was a steppe-tundra which probably covered the Tanana Lowland and much of the adjacent Yukon-Tanana Upland during full glacial conditions of the late Wisconsin, until about 14,000 radiocarbon years ago. Inferred climate during the time of steppe-tundra was significantly drier than at present, with a mean annual temperature at least several degrees colder than the present figure of -4°C. Increased continentality probably resulted in warm, dry summers of short duration, and long severe winters. Pollen Zone 2 persisted from about 14,000 years ago until about 10,000 years ago. Zone 2 pollen spectra are characterized by very high percentages of dwarf birch pollen and lower but significant percentages of grass, sedge, and willow pollen. Zone 2 vegetation was a form of shrub tundra. The transition from Zone 1 to Zone 2 appears to have been abrupt and may reflect a sudden climatic change to warmer and moister conditions about 14,000 years ago. Absolute Pollen Influx data (API) show at least a 3-fold increase in the rate of pollen deposition in Zone 2 time over Zone 1 time. Pollen Zone 3 is subdivided into Subzones 3A and 3B. Subzone 3A records the invasion of spruce into the region, beginning roughly 10,000 years ago. Most of the pollen histories from the region show a rather abrupt initial increase in spruce pollen percentages. The Birch Lake Core II record displays a more gradual initial increase however, which suggests that spruce trees did not actually reach the vicinity of Birch Lake, and perhaps the Fairbanks area, until about 9000 years B.P. The invasion of spruce probably proceeded along rivers initially, forming gallery forests surrounded by shrub tundra. By about 9000 years B.P.forests were evidently well-established in much of the region. The spruce invasion suggests a further climatic warming, but the radiocarbon chronology is not yet sufficiently detailed to pinpoint the time of initial increase in spruce pollen in the cores. Therefore, it is uncertain whether the invading spruce arrived from distant refugium many years after the climate had become suitable in interior Alaska, or a few scattered spruce did survive in or near the Tanana Valley during the late Wisconsin glaciations and expanded their range immediately when climatic conditions allowed. Subzone 3B spans the past 8400 years. The boundary between Subzones 3A and 3B is marked by an increase in alder percentages and the onset of a decline in spruce pollen percentages. Spruce pollen percentages and API continued to decline until about 7000 years B.P., perhaps as an indirect result of an interval of warmer, drier climate. Lowland vegetation of the region has undergone no significant change during the past 6500 years insofar as can be discerned from the pollen record.U.S. National Science Foundation Grant DES 73-06503-A01

A portable sensor system for the detection of human volatile compounds against transnational crime

Human smuggling accounts for a significant part of transnational organized crime, creating a growing threat to national and international security and putting at risk the health and lives of the people being smuggled. Early detection and interception of human beings hidden in containers or trucks are therefore of considerable importance, especially at key transportation hubs, such as at international borders and harbors. The major challenge is to provide fast inspection procedures without needing to open sealed trucks and containers. The detection of trace key volatile organic compounds, which includes aldehydes and ketones, emitted by humans can be used to rapidly determine human presence, requiring only several ml of air to be taken from inside a container. In this paper, we describe a prototype portable device for the rapid detection of hidden or entrapped people, employing a combined ion mobility spectrometer and sensor array system for obtaining a volatile signature of human presence. The detection limits of this combined analytical device are sufficiently low for use in sensing ketones and aldehydes being emitted by humans in closed containers. For easy handling by security personnel, a classification algorithm is applied that provides a simple YES or NO decision. With a training dataset of more than 1000 measurements, the algorithm achieved an area under curve of 0.9 for untrained scenarios. The field measurements show that two people need to stay in a car for between 20 and 30 minutes in order for the emitted trace volatile organic compounds to reach concentrations high enough for reliable detection with our analytical device

Airborne electromagnetic imaging of discontinuous permafrost

The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to stream flow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering ~1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past ~4 million years and the configuration of permafrost to depths of ~100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south, making it an important location for examining permafrost dynamics. Our results not only provide a detailed snapshot of the present-day configuration of permafrost, but they also expose previously unseen details about potential surface – groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past 1,000 years. This work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic, climatic, and ecological processes, and has significant implications for the stewardship of Arctic environments

Gratitude and hospitality: Tamil refugee employment in London and the conditional nature of integration

Healy, R. L. 2014. The definitive, peer-reviewed and edited version of this article is published in Environment and Planning A, 2014, 46(3), pp. 614-628, http:dx/doi.org/10.1068/a4655The policy of integration attempts to address different elements of exclusion, yet relatively little research has considered what integration means to the refugees themselves. This paper explores one key area for supporting integration: employment.ESRC PTA-030-2005-0082

Chemical Power for Microscopic Robots in Capillaries

The power available to microscopic robots (nanorobots) that oxidize bloodstream glucose while aggregated in circumferential rings on capillary walls is evaluated with a numerical model using axial symmetry and time-averaged release of oxygen from passing red blood cells. Robots about one micron in size can produce up to several tens of picowatts, in steady-state, if they fully use oxygen reaching their surface from the blood plasma. Robots with pumps and tanks for onboard oxygen storage could collect oxygen to support burst power demands two to three orders of magnitude larger. We evaluate effects of oxygen depletion and local heating on surrounding tissue. These results give the power constraints when robots rely entirely on ambient available oxygen and identify aspects of the robot design significantly affecting available power. More generally, our numerical model provides an approach to evaluating robot design choices for nanomedicine treatments in and near capillaries.Comment: 28 pages, 7 figure

Resilience of refugees displaced in the developing world: a qualitative analysis of strengths and struggles of urban refugees in Nepal

BACKGROUND: Mental health and psychosocial wellbeing are key concerns in displaced populations. Despite urban refugees constituting more than half of the world's refugees, minimal attention has been paid to their psychosocial wellbeing. The purpose of this study was to assess coping behaviour and aspects of resilience amongst refugees in Kathmandu, Nepal. METHODS: This study examined the experiences of 16 Pakistani and 8 Somali urban refugees in Kathmandu, Nepal through in-depth individual interviews, focus groups, and Photovoice methodology. Such qualitative approaches enabled us to broadly discuss themes such as personal experiences of being a refugee in Kathmandu, perceived causes of psychosocial distress, and strategies and resources for coping. Thematic network analysis was used in this study to systematically interpret and code the data. RESULTS: Our findings highlight that urban refugees' active coping efforts, notwithstanding significant adversity and resulting distress, are most frequently through primary relationships. Informed by Axel Honneth's theory on the struggle for recognition, findings suggest that coping is a function beyond the individual and involves the ability to negotiate recognition. This negotiation involves not only primary relationships, but also the legal order and other social networks such as family and friends. Honneth's work was used because of its emphasis on the importance of legal recognition and larger structural factors in facilitating daily coping. CONCLUSIONS: Understanding how urban refugees cope by negotiating access to various forms of recognition in the absence of legal-recognition will enable organisations working with them to leverage such strengths and develop relevant programmes. In particular, building on these existing resources will lead to culturally compelling and sustainable care for these populations

Wildfire Risk as a Socioecological Pathology

Wildfire risk in temperate forests has become a nearly intractable problem that can be characterized as a socioecological “pathology”: that is, a set of complex and problematic interactions among social and ecological systems across multiple spatial and temporal scales. Assessments of wildfire risk could benefit from recognizing and accounting for these interactions in terms of socioecological systems, also known as coupled natural and human systems (CNHS). We characterize the primary social and ecological dimensions of the wildfire risk pathology, paying particular attention to the governance system around wildfire risk, and suggest strategies to mitigate the pathology through innovative planning approaches, analytical tools, and policies. We caution that even with a clear understanding of the problem and possible solutions, the system by which human actors govern fire-prone forests may evolve incrementally in imperfect ways and can be expected to resist change even as we learn better ways to manage CNHS

Solid state quantum memory using the 31P nuclear spin

The transfer of information between different physical forms is a central theme in communication and computation, for example between processing entities and memory. Nowhere is this more crucial than in quantum computation, where great effort must be taken to protect the integrity of a fragile quantum bit. Nuclear spins are known to benefit from long coherence times compared to electron spins, but are slow to manipulate and suffer from weak thermal polarisation. A powerful model for quantum computation is thus one in which electron spins are used for processing and readout while nuclear spins are used for storage. Here we demonstrate the coherent transfer of a superposition state in an electron spin 'processing' qubit to a nuclear spin 'memory' qubit, using a combination of microwave and radiofrequency pulses applied to 31P donors in an isotopically pure 28Si crystal. The electron spin state can be stored in the nuclear spin on a timescale that is long compared with the electron decoherence time and then coherently transferred back to the electron spin, thus demonstrating the 31P nuclear spin as a solid-state quantum memory. The overall store/readout fidelity is about 90%, attributed to systematic imperfections in radiofrequency pulses which can be improved through the use of composite pulses. We apply dynamic decoupling to protect the nuclear spin quantum memory element from sources of decoherence. The coherence lifetime of the quantum memory element is found to exceed one second at 5.5K.Comment: v2: Tomography added and storage of general initial state

Examining fire-prone forest landscapes as coupled human and natural systems

Fire-prone landscapes are not well studied as coupled human and natural systems (CHANS) and present many challenges for understanding and promoting adaptive behaviors and institutions. Here, we explore how heterogeneity, feedbacks, and external drivers in this type of natural hazard system can lead to complexity and can limit the development of more adaptive approaches to policy and management. Institutions and social networks can counter these limitations and promote adaptation. We also develop a conceptual model that includes a robust characterization of social subsystems for a fire-prone landscape in Oregon and describe how we are building an agent-based model to promote understanding of this social-ecological system. Our agent-based model, which incorporates existing ecological models of vegetation and fire and is based on empirical studies of landowner decision-making, will be used to explore alternative management and fire scenarios with land managers and various public entities. We expect that the development of CHANS frameworks and the application of a simulation model in a collaborative setting will facilitate the development of more effective policies and practices for fire-prone landscapes