52 research outputs found
Factors limiting productivity of the Central Arctic Caribou Herd of Alaska
Many biotic and abiotic factors can limit productivity and growth of caribou (Rangifer tarandus) herds, but limiting factors typically vary by region. Identifying limiting factors may help to indicate which seasons are of relative importance to a caribou herd and possibly to suggest general life history strategies. Using regression techniques, we found that despite previous suggestions, net productivity of Alaska’s Central Arctic Caribou Herd (CAH) did not respond to early summer forage biomass or summer insect severity from the previous year. Abiotic factors that did have apparent effects on CAH productivity included early fall snow deposition, winter snow condition, and spring snow ablation. To achieve a suitable weight for conception, caribou of the CAH may exhibit a seasonal time-minimizing foraging strategy by moderating weight gain during the warm summer insect season and feeding more intensively during the insect-free weeks before the autumn rut. A long-term trend of the Northern Hemisphere annular mode (NAM) may be linked to anthropogenic climate change and may have negative implications for the future success of the CAH
Utopian connectivity to paranoid collapse: complex networks and global social ecologies in 20th-century fiction
This project treats complex systems, specifically global social and ecological networks, as central to understanding modern explorations and experiences of utopian connectivity and stability alongside dystopian paranoia and precarity. Through an examination of the fiction of Charlotte Perkins Gilman, James Joyce, and David Mitchell, I analyze strengths and vulnerabilities of such systems. Gilmanâs perfectly controlled and aggressively managed ecosystems are undercut by potentially catastrophic losses in biodiversity. Joyceâs celebratory view of networks and links across cosmic scales requires an acknowledgement and acceptance of humanityâs relative powerlessness in the face of such universal connections, which dwarf global economic and social networks. Mitchell illustrates how subtle social linkings across time and space can add up to create powerful technological, ecological, and social effects. However, the power in Mitchellâs dense global network is also its weakness; in Ghostwritten, efficiency in information transfer can be used for positive outcomes as well as to effect total apocalypse.
Alongside and enmeshed with my analysis of Mitchellâs Ghostwritten, I present a comparison of manual and automatic methods I created for extracting social networks from literary texts as a first step toward developing a broadly applicable network extraction method. My proof of concept indicates that, with further iterations and refinements, it should be possible to establish a practical, reliable, and effective method for extracting and understanding social networks in novels, with the aim of using these models to understand more deeply the texts themselves and what they suggest about human experience, policy, and futurity
Dynamic Responses of Calving Caribou to Oilfields in Northern Alaska
Past research has suggested that during the calving period, caribou (Rangifer tarandus) in Arctic Alaska generally avoid areas within 1 km of oilfield roads with traffic. However, avoidance is not absolute, and caribou may habituate to infrastructure (e.g., buildings, roads, well pads) and human activity. We conducted road-based surveys of caribou in oilfields on Alaskaâs Arctic Coastal Plain during the late calving and post-calving periods of June in 2000â02. We recorded location, composition, and behavior of caribou groups located less than 1 km from active gravel roads and production pads. Caribou groups with calves were on average distributed farther from oilfield infrastructure than were groups without calves, but habituation to oilfield activities, indicated by decreased avoidance, occurred at similar rates for groups with and without calves. During the calving period, sighting rates were greater in areas of low human activity, and calf percentages tended to be greater at night when oilfield activity was reduced. Caribou groups were on average closer to infrastructure during the post-calving periods than during the calving periods in 2000 and 2001, but not in 2002. In 2002, when snow melted early, caribou groups were closer to infrastructure during the calving period than in 2000 and 2001, when snow melted later, emphasizing the importance of examining environmental variables when investigating the dynamic interactions of caribou and oilfields. Overall, caribou appeared to habituate to active oilfield infrastructure after the calving period in 2000, late in the calving period in 2001, and likely before our sampling period in 2002. The timing of annual rehabituation was positively correlated with timing of spring snowmelt. Land and wildlife managers can use information from this study to develop calving period-specific mitigation measures that are more effective and flexible.Selon des recherches antĂ©rieures, pendant sa pĂ©riode de vĂȘlage, le caribou (Rangifer tarandus) de lâAlaska arctique Ă©vite gĂ©nĂ©ralement les rĂ©gions se trouvant Ă lâintĂ©rieur dâun kilomĂštre des routes oĂč circulent des vĂ©hicules menant aux chantiers pĂ©troliers. Cependant, cet Ă©vitement nâest pas absolu, et le caribou peut sâaccoutumer aux infrastructures (comme les bĂątiments, les routes et les chantiers) et Ă lâactivitĂ© humaine. Nous avons effectuĂ© le dĂ©nombrement des caribous prĂšs des routes des champs de pĂ©trole de la plaine cĂŽtiĂšre arctique de lâAlaska vers la fin de la pĂ©riode de vĂȘlage et aprĂšs la pĂ©riode de vĂȘlage de juin 2000 Ă 2002. Nous avons consignĂ© lâemplacement, la composition et le comportement des groupes de caribous se trouvant Ă moins dâun kilomĂštre des routes de gravier et des chantiers de production en activitĂ©. En moyenne, les caribous qui avaient des petits se tenaient plus loin des infrastructures pĂ©troliĂšres que les groupes de caribous qui nâavaient pas de petits. Cela dit, lâaccoutumance aux activitĂ©s pĂ©troliĂšres, dĂ©notĂ©e par un moins grand Ă©vitement, survenait Ă des taux semblables pour les groupes qui avaient des petits et les groupes qui nâen avaient pas. Pendant la pĂ©riode de vĂȘlage, les taux dâobservation de caribous Ă©taient plus Ă©levĂ©s dans les rĂ©gions oĂč il y avait peu dâactivitĂ© humaine, et les pourcentages de petits avaient tendance Ă ĂȘtre plus Ă©levĂ©s la nuit, lorsquâil y avait peu de va-et-vient aux chantiers. En moyenne, les groupes de caribous sâapprochaient plus des infrastructures pendant les pĂ©riodes suivant le vĂȘlage des annĂ©es 2000 et 2001, mais pas en 2002. En 2002, quand la neige a fondu plus tĂŽt que dâhabitude, les groupes de caribous sâapprochaient plus des infrastructures pendant la pĂ©riode de vĂȘlage quâen 2000 et 2001, lorsque la neige a fondu plus tard. Cela fait ressortir lâimportance de tenir compte des variables environnementales lorsque nous faisons des enquĂȘtes sur les interactions dynamiques entre les caribous et les champs de pĂ©trole. Dans lâensemble, les caribous semblaient sâaccoutumer aux infrastructures pĂ©troliĂšres en activitĂ© aprĂšs la pĂ©riode de vĂȘlage en 2000, puis vers la fin de la pĂ©riode de vĂȘlage en 2001, et vraisemblablement avant notre pĂ©riode dâĂ©chantillonnage en 2002. Le moment de lâaccoutumance annuelle coĂŻncidait positivement avec le moment de la fonte des neiges au printemps. Les gestionnaires des terres et de la faune peuvent se servir de lâinformation Ă©manant de cette Ă©tude pour Ă©laborer des mesures dâattĂ©nuation tenant compte de la pĂ©riode de vĂȘlage, mesures qui sont plus efficaces et qui prĂ©sentent plus de souplesse
Code wars: steganography, signals intelligence, and terrorism
This paper describes and discusses the process of secret communication known as steganography. The argument advanced here is that terrorists are unlikely to be employing digital steganography to facilitate secret intra-group communication as has been claimed. This is because terrorist use of digital steganography is both technically and operationally implausible. The position adopted in this paper is that terrorists are likely to employ low-tech steganography such as semagrams and null ciphers instead
Mapping Genre at the Page Level in English-Language Volumes from HathiTrust, 1700-1899
Using regularized logistic regression and hidden Markov models, we predict genre at the page level in a collection of 469,000 volumes from HathiTrust Digital Library. Accuracy is comparable to human crowdsourcing.Ope
Transit Timing Observations from Kepler: VI. Potentially interesting candidate systems from Fourier-based statistical tests
We analyze the deviations of transit times from a linear ephemeris for the
Kepler Objects of Interest (KOI) through Quarter six (Q6) of science data. We
conduct two statistical tests for all KOIs and a related statistical test for
all pairs of KOIs in multi-transiting systems. These tests identify several
systems which show potentially interesting transit timing variations (TTVs).
Strong TTV systems have been valuable for the confirmation of planets and their
mass measurements. Many of the systems identified in this study should prove
fruitful for detailed TTV studies.Comment: 32 pages, 6 of text and one long table, Accepted to Ap
Two Earth-sized planets orbiting Kepler-20
Since the discovery of the first extrasolar giant planets around Sun-like
stars, evolving observational capabilities have brought us closer to the
detection of true Earth analogues. The size of an exoplanet can be determined
when it periodically passes in front of (transits) its parent star, causing a
decrease in starlight proportional to its radius. The smallest exoplanet
hitherto discovered has a radius 1.42 times that of the Earth's radius (R
Earth), and hence has 2.9 times its volume. Here we report the discovery of two
planets, one Earth-sized (1.03R Earth) and the other smaller than the Earth
(0.87R Earth), orbiting the star Kepler-20, which is already known to host
three other, larger, transiting planets. The gravitational pull of the new
planets on the parent star is too small to measure with current
instrumentation. We apply a statistical method to show that the likelihood of
the planetary interpretation of the transit signals is more than three orders
of magnitude larger than that of the alternative hypothesis that the signals
result from an eclipsing binary star. Theoretical considerations imply that
these planets are rocky, with a composition of iron and silicate. The outer
planet could have developed a thick water vapour atmosphere.Comment: Letter to Nature; Received 8 November; accepted 13 December 2011;
Published online 20 December 201
Measuring performance on the Healthcare Access and Quality Index for 195 countries and territories and selected subnational locations: A systematic analysis from the Global Burden of Disease Study 2016
Background: A key component of achieving universal health coverage is ensuring that all populations have access to quality health care. Examining where gains have occurred or progress has faltered across and within countries is crucial to guiding decisions and strategies for future improvement. We used the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) to assess personal health-care access and quality with the Healthcare Access and Quality (HAQ) Index for 195 countries and territories, as well as subnational locations in seven countries, from 1990 to 2016. Methods Drawing from established methods and updated estimates from GBD 2016, we used 32 causes from which death should not occur in the presence of effective care to approximate personal health-care access and quality by location and over time. To better isolate potential effects of personal health-care access and quality from underlying risk factor patterns, we risk-standardised cause-specific deaths due to non-cancers by location-year, replacing the local joint exposure of environmental and behavioural risks with the global level of exposure. Supported by the expansion of cancer registry data in GBD 2016, we used mortality-to-incidence ratios for cancers instead of risk-standardised death rates to provide a stronger signal of the effects of personal health care and access on cancer survival. We transformed each cause to a scale of 0-100, with 0 as the first percentile (worst) observed between 1990 and 2016, and 100 as the 99th percentile (best); we set these thresholds at the country level, and then applied them to subnational locations. We applied a principal components analysis to construct the HAQ Index using all scaled cause values, providing an overall score of 0-100 of personal health-care access and quality by location over time. We then compared HAQ Index levels and trends by quintiles on the Socio-demographic Index (SDI), a summary measure of overall development. As derived from the broader GBD study and other data sources, we examined relationships between national HAQ Index scores and potential correlates of performance, such as total health spending per capita. Findings In 2016, HAQ Index performance spanned from a high of 97\ub71 (95% UI 95\ub78-98\ub71) in Iceland, followed by 96\ub76 (94\ub79-97\ub79) in Norway and 96\ub71 (94\ub75-97\ub73) in the Netherlands, to values as low as 18\ub76 (13\ub71-24\ub74) in the Central African Republic, 19\ub70 (14\ub73-23\ub77) in Somalia, and 23\ub74 (20\ub72-26\ub78) in Guinea-Bissau. The pace of progress achieved between 1990 and 2016 varied, with markedly faster improvements occurring between 2000 and 2016 for many countries in sub-Saharan Africa and southeast Asia, whereas several countries in Latin America and elsewhere saw progress stagnate after experiencing considerable advances in the HAQ Index between 1990 and 2000. Striking subnational disparities emerged in personal health-care access and quality, with China and India having particularly large gaps between locations with the highest and lowest scores in 2016. In China, performance ranged from 91\ub75 (89\ub71-93\ub76) in Beijing to 48\ub70 (43\ub74-53\ub72) in Tibet (a 43\ub75-point difference), while India saw a 30\ub78-point disparity, from 64\ub78 (59\ub76-68\ub78) in Goa to 34\ub70 (30\ub73-38\ub71) in Assam. Japan recorded the smallest range in subnational HAQ performance in 2016 (a 4\ub78-point difference), whereas differences between subnational locations with the highest and lowest HAQ Index values were more than two times as high for the USA and three times as high for England. State-level gaps in the HAQ Index in Mexico somewhat narrowed from 1990 to 2016 (from a 20\ub79-point to 17\ub70-point difference), whereas in Brazil, disparities slightly increased across states during this time (a 17\ub72-point to 20\ub74-point difference). Performance on the HAQ Index showed strong linkages to overall development, with high and high-middle SDI countries generally having higher scores and faster gains for non-communicable diseases. Nonetheless, countries across the development spectrum saw substantial gains in some key health service areas from 2000 to 2016, most notably vaccine-preventable diseases. Overall, national performance on the HAQ Index was positively associated with higher levels of total health spending per capita, as well as health systems inputs, but these relationships were quite heterogeneous, particularly among low-to-middle SDI countries. Interpretation GBD 2016 provides a more detailed understanding of past success and current challenges in improving personal health-care access and quality worldwide. Despite substantial gains since 2000, many low-SDI and middle- SDI countries face considerable challenges unless heightened policy action and investments focus on advancing access to and quality of health care across key health services, especially non-communicable diseases. Stagnating or minimal improvements experienced by several low-middle to high-middle SDI countries could reflect the complexities of re-orienting both primary and secondary health-care services beyond the more limited foci of the Millennium Development Goals. Alongside initiatives to strengthen public health programmes, the pursuit of universal health coverage hinges upon improving both access and quality worldwide, and thus requires adopting a more comprehensive view-and subsequent provision-of quality health care for all populations
Measuring performance on the Healthcare Access and Quality Index for 195 countries and territories and selected subnational locations: A systematic analysis from the Global Burden of Disease Study 2016
Copyright © 2018 The Author(s). Published by Elsevier Ltd. Background A key component of achieving universal health coverage is ensuring that all populations have access to quality health care. Examining where gains have occurred or progress has faltered across and within countries is crucial to guiding decisions and strategies for future improvement. We used the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) to assess personal health-care access and quality with the Healthcare Access and Quality (HAQ) Index for 195 countries and territories, as well as subnational locations in seven countries, from 1990 to 2016. Methods Drawing from established methods and updated estimates from GBD 2016, we used 32 causes from which death should not occur in the presence of effective care to approximate personal health-care access and quality by location and over time. To better isolate potential effects of personal health-care access and quality from underlying risk factor patterns, we risk-standardised cause-specific deaths due to non-cancers by location-year, replacing the local joint exposure of environmental and behavioural risks with the global level of exposure. Supported by the expansion of cancer registry data in GBD 2016, we used mortality-to-incidence ratios for cancers instead of risk-standardised death rates to provide a stronger signal of the effects of personal health care and access on cancer survival. We transformed each cause to a scale of 0-100, with 0 as the first percentile (worst) observed between 1990 and 2016, and 100 as the 99th percentile (best); we set these thresholds at the country level, and then applied them to subnational locations. We applied a principal components analysis to construct the HAQ Index using all scaled cause values, providing an overall score of 0-100 of personal health-care access and quality by location over time. We then compared HAQ Index levels and trends by quintiles on the Socio-demographic Index (SDI), a summary measure of overall development. As derived from the broader GBD study and other data sources, we examined relationships between national HAQ Index scores and potential correlates of performance, such as total health spending per capita. Findings In 2016, HAQ Index performance spanned from a high of 97·1 (95% UI 95·8-98·1) in Iceland, followed by 96·6 (94·9-97·9) in Norway and 96·1 (94·5-97·3) in the Netherlands, to values as low as 18·6 (13·1-24·4) in the Central African Republic, 19·0 (14·3-23·7) in Somalia, and 23·4 (20·2-26·8) in Guinea-Bissau. The pace of progress achieved between 1990 and 2016 varied, with markedly faster improvements occurring between 2000 and 2016 for many countries in sub-Saharan Africa and southeast Asia, whereas several countries in Latin America and elsewhere saw progress stagnate after experiencing considerable advances in the HAQ Index between 1990 and 2000. Striking subnational disparities emerged in personal health-care access and quality, with China and India having particularly large gaps between locations with the highest and lowest scores in 2016. In China, performance ranged from 91·5 (89·1-93·6) in Beijing to 48·0 (43·4-53·2) in Tibet (a 43·5-point difference), while India saw a 30·8-point disparity, from 64·8 (59·6-68·8) in Goa to 34·0 (30·3-38·1) in Assam. Japan recorded the smallest range in subnational HAQ performance in 2016 (a 4·8-point difference), whereas differences between subnational locations with the highest and lowest HAQ Index values were more than two times as high for the USA and three times as high for England. State-level gaps in the HAQ Index in Mexico somewhat narrowed from 1990 to 2016 (from a 20·9-point to 17·0-point difference), whereas in Brazil, disparities slightly increased across states during this time (a 17·2-point to 20·4-point difference). Performance on the HAQ Index showed strong linkages to overall development, with high and high-middle SDI countries generally having higher scores and faster gains for non-communicable diseases. Nonetheless, countries across the development spectrum saw substantial gains in some key health service areas from 2000 to 2016, most notably vaccine-preventable diseases. Overall, national performance on the HAQ Index was positively associated with higher levels of total health spending per capita, as well as health systems inputs, but these relationships were quite heterogeneous, particularly among low-to-middle SDI countries. Interpretation GBD 2016 provides a more detailed understanding of past success and current challenges in improving personal health-care access and quality worldwide. Despite substantial gains since 2000, many low-SDI and middle- SDI countries face considerable challenges unless heightened policy action and investments focus on advancing access to and quality of health care across key health services, especially non-communicable diseases. Stagnating or minimal improvements experienced by several low-middle to high-middle SDI countries could reflect the complexities of re-orienting both primary and secondary health-care services beyond the more limited foci of the Millennium Development Goals. Alongside initiatives to strengthen public health programmes, the pursuit of universal health coverage hinges upon improving both access and quality worldwide, and thus requires adopting a more comprehensive view - and subsequent provision - of quality health care for all populations
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