Reconstructing Late Holocene North Atlantic atmospheric circulation changes using functional paleoclimate networks

Science.gov (United States)

Franke, Jasper G.; Werner, Johannes P.; Donner, Reik V.

2017-11-01

Obtaining reliable reconstructions of long-term atmospheric circulation changes in the North Atlantic region presents a persistent challenge to contemporary paleoclimate research, which has been addressed by a multitude of recent studies. In order to contribute a novel methodological aspect to this active field, we apply here evolving functional network analysis, a recently developed tool for studying temporal changes of the spatial co-variability structure of the Earth's climate system, to a set of Late Holocene paleoclimate proxy records covering the last two millennia. The emerging patterns obtained by our analysis are related to long-term changes in the dominant mode of atmospheric circulation in the region, the North Atlantic Oscillation (NAO). By comparing the time-dependent inter-regional linkage structures of the obtained functional paleoclimate network representations to a recent multi-centennial NAO reconstruction, we identify co-variability between southern Greenland, Svalbard, and Fennoscandia as being indicative of a positive NAO phase, while connections from Greenland and Fennoscandia to central Europe are more pronounced during negative NAO phases. By drawing upon this correspondence, we use some key parameters of the evolving network structure to obtain a qualitative reconstruction of the NAO long-term variability over the entire Common Era (last 2000 years) using a linear regression model trained upon the existing shorter reconstruction.

Phil Wallace and Theoretical Physics at McGill in the 1950's: A Personal Perspective

International Nuclear Information System (INIS)

Jackson, John David

2010-01-01

In 1946 Philip (Phil) Russell Wallace joined the Mathematics Department of McGill University as an Associate Professor of Applied Mathematics, apparently because A. H. S. Gillson, Dean of Arts and Science, wanted theoretical physicists to be in the Mathematics Department. He came with the dream of creating a theoretical physics group at McGill. By the spring of 1949, Phil was authorized to recruit two junior faculty in Mathematics. He hired Theodore (Ted) F. Morris from U. Toronto, who joined in September 1949, and me, who came in January 1950. The group had begun. Phil Wallace was born in Toronto in 1915 and grew up there. He entered the University of Toronto in 1933, earned a B.A. in mathematics in 1937, a M.A. in 1938, and a Ph.D. in applied mathematics in 1940 under Leopold Infeld. His Ph.D. thesis in general relativity was entitled 'On the relativistic equations of motion in electromagnetic theory.' In 1940 World War II had engulfed Europe and was having its effect on Canada, but the US was still at peace. L. J. Synge, Head of the Applied Mathematics Department at Toronto, told Wallace that people such as he would be needed in war work, but things were not ready quite yet. Hold yourself ready. Phil took a two-year position as lecturer in mathematics at the University of Cincinnati (1940-42); in the fall of 1942 he became a lecturer in mathematics at M.I.T. It was from there that he was recruited by Synge to join the war effort from 1943 to 1946 at N.R.C.'s Montreal Laboratory, the genesis of the Canadian Atomic Energy Project. Phil has described those heady wartime years in these pages. Much of the effort of the theoretical physicists was on nuclear reactor theory and the properties of relevant materials, such as graphite, under long and intense neutron bombardment. In late 1945 Phil was sent for four months to Bristol to learn about the properties of graphite from the esteemed N. F. Mott. This exposure led Phil to a life-long interest in graphite and in

Validation of the Danish version of the McGill Ingestive Skills Assessment using classical test theory and the Rasch model

DEFF Research Database (Denmark)

Hansen, Tina; Lambert, Heather C; Faber, Jens

2012-01-01

Purpose: The study aimed to validate the Danish version of the Canadian the "McGill Ingestive Skills Assessment" (MISA-DK) for measuring dysphagia in frail elders. Method: One-hundred and ten consecutive older medical patients were recruited to the study. Reliability was assessed by internal...... consistency (Chronbach's alpha). External construct validity (convergent and known-groups validity) was evaluated against theoretical constructs assessing the complex concept of ingestive skills. Internal construct validity was tested using Rasch analysis. Results: High internal consistency reliability...... with Chronbach's alpha of 0.77-0.95 was evident. External construct validity was supported by expected high correlations with most of the constructs related to ingestive skills (r(s)¿=¿0.53 to r(s)¿=¿0.66). The MISA-DK discriminated significantly between known-groups. Fit to the Rasch model (x(2) (df)¿=¿12 (12...

Comparing Apples to Apples: Paleoclimate Model-Data comparison via Proxy System Modeling

Science.gov (United States)

Dee, Sylvia; Emile-Geay, Julien; Evans, Michael; Noone, David

2014-05-01

The wealth of paleodata spanning the last millennium (hereinafter LM) provides an invaluable testbed for CMIP5-class GCMs. However, comparing GCM output to paleodata is non-trivial. High-resolution paleoclimate proxies generally contain a multivariate and non-linear response to regional climate forcing. Disentangling the multivariate environmental influences on proxies like corals, speleothems, and trees can be complex due to spatiotemporal climate variability, non-stationarity, and threshold dependence. Given these and other complications, many paleodata-GCM comparisons take a leap of faith, relating climate fields (e.g. precipitation, temperature) to geochemical signals in proxy data (e.g. δ18O in coral aragonite or ice cores) (e.g. Braconnot et al., 2012). Isotope-enabled GCMs are a step in the right direction, with water isotopes providing a connector point between GCMs and paleodata. However, such studies are still rare, and isotope fields are not archived as part of LM PMIP3 simulations. More importantly, much of the complexity in how proxy systems record and transduce environmental signals remains unaccounted for. In this study we use proxy system models (PSMs, Evans et al., 2013) to bridge this conceptual gap. A PSM mathematically encodes the mechanistic understanding of the physical, geochemical and, sometimes biological influences on each proxy. To translate GCM output to proxy space, we have synthesized a comprehensive, consistently formatted package of published PSMs, including δ18O in corals, tree ring cellulose, speleothems, and ice cores. Each PSM is comprised of three sub-models: sensor, archive, and observation. For the first time, these different components are coupled together for four major proxy types, allowing uncertainties due to both dating and signal interpretation to be treated within a self-consistent framework. The output of this process is an ensemble of many (say N = 1,000) realizations of the proxy network, all equally plausible

Development of a North American paleoclimate pollen-based reconstruction database application

Science.gov (United States)

Ladd, Matthew; Mosher, Steven; Viau, Andre

2013-04-01

Recent efforts in synthesizing paleoclimate records across the globe has warranted an effort to standardize the different paleoclimate archives currently available in order to facilitate data-model comparisons and hence improve our estimates of future climate change. It is often the case that the methodology and programs make it challenging for other researchers to reproduce the results for a reconstruction, therefore there is a need for to standardize paleoclimate reconstruction databases in an application specific to proxy data. Here we present a methodology using the open source R language using North American pollen databases (e.g. NAPD, NEOTOMA) where this application can easily be used to perform new reconstructions and quickly analyze and output/plot the data. The application was developed to easily test methodological and spatial/temporal issues that might affect the reconstruction results. The application allows users to spend more time analyzing and interpreting results instead of on data management and processing. Some of the unique features of this R program are the two modules each with a menu making the user feel at ease with the program, the ability to use different pollen sums, select one of 70 climate variables available, substitute an appropriate modern climate dataset, a user-friendly regional target domain, temporal resolution criteria, linear interpolation and many other features for a thorough exploratory data analysis. The application program will be available for North American pollen-based reconstructions and eventually be made available as a package through the CRAN repository by late 2013.

Synthesizing late Holocene paleoclimate reconstructions: Lessons learned, common challenges, and implications for future research

Science.gov (United States)

Rodysill, J. R.

2017-12-01

Proxy-based reconstructions provide vital information for developing histories of environmental and climate changes. Networks of spatiotemporal paleoclimate information are powerful tools for understanding dynamical processes within the global climate system and improving model-based predictions of the patterns and magnitudes of climate changes at local- to global-scales. Compiling individual paleoclimate records and integrating reconstructed climate information in the context of an ensemble of multi-proxy records, which are fundamental for developing a spatiotemporal climate data network, are hindered by challenges related to data and information accessibility, chronological uncertainty, sampling resolution, climate proxy type, and differences between depositional environments. The U.S. Geological Survey (USGS) North American Holocene Climate Synthesis Working Group has been compiling and integrating multi-proxy paleoclimate data as part of an ongoing effort to synthesize Holocene climate records from North America. The USGS North American Holocene Climate Synthesis Working Group recently completed a late Holocene hydroclimate synthesis for the North American continent using several proxy types from a range of depositional environments, including lakes, wetlands, coastal marine, and cave speleothems. Using new age-depth relationships derived from the Bacon software package, we identified century-scale patterns of wetness and dryness for the past 2000 years with an age uncertainty-based confidence rating for each proxy record. Additionally, for highly-resolved North American lake sediment records, we computed average late Holocene sediment deposition rates and identified temporal trends in age uncertainty that are common to multiple lakes. This presentation addresses strengths and challenges of compiling and integrating data from different paleoclimate archives, with a particular focus on lake sediments, which may inform and guide future paleolimnological studies.

Tracking variable sedimentation rates in orbitally forced paleoclimate proxy series

Science.gov (United States)

Li, M.; Kump, L. R.; Hinnov, L.

2017-12-01

This study addresses two fundamental issues in cyclostratigraphy: quantitative testing of orbital forcing in cyclic sedimentary sequences and tracking variable sedimentation rates. The methodology proposed here addresses these issues as an inverse problem, and estimates the product-moment correlation coefficient between the frequency spectra of orbital solutions and paleoclimate proxy series over a range of "test" sedimentation rates. It is inspired by the ASM method (1). The number of orbital parameters involved in the estimation is also considered. The method relies on the hypothesis that orbital forcing had a significant impact on the paleoclimate proxy variations, and thus is also tested. The null hypothesis of no astronomical forcing is evaluated using the Beta distribution, for which the shape parameters are estimated using a Monte Carlo simulation approach. We introduce a metric to estimate the most likely sedimentation rate using the product-moment correlation coefficient, H0 significance level, and the number of contributing orbital parameters, i.e., the CHO value. The CHO metric is applied with a sliding window to track variable sedimentation rates along the paleoclimate proxy series. Two forward models with uniform and variable sedimentation rates are evaluated to demonstrate the robustness of the method. The CHO method is applied to the classical Late Triassic Newark depth rank series; the estimated sedimentation rates match closely with previously published sedimentation rates and provide a more highly time-resolved estimate (2,3). References: (1) Meyers, S.R., Sageman, B.B., Amer. J. Sci., 307, 773-792, 2007; (2) Kent, D.V., Olsen, P.E., Muttoni, G., Earth-Sci. Rev.166, 153-180, 2017; (3) Li, M., Zhang, Y., Huang, C., Ogg, J., Hinnov, L., Wang, Y., Zou, Z., Li, L., 2017. Earth Plant. Sc. Lett. doi:10.1016/j.epsl.2017.07.015

Autogenic geomorphic processes determine the resolution and fidelity of terrestrial paleoclimate records

OpenAIRE

Foreman, Brady Z.; Straub, Kyle M.

2017-01-01

Terrestrial paleoclimate records rely on proxies hosted in alluvial strata whose beds are deposited by unsteady and nonlinear geomorphic processes. It is broadly assumed that this renders the resultant time series of terrestrial paleoclimatic variability noisy and incomplete. We evaluate this assumption using a model of oscillating climate and the precise topographic evolution of an experimental alluvial system. We find that geomorphic stochasticity can create aliasing in the time series and ...

Complex Empiricism and the Quantification of Uncertainty in Paleoclimate Reconstructions

Science.gov (United States)

Brumble, K. C.

2014-12-01

Because the global climate cannot be observed directly, and because of vast and noisy data sets, climate science is a rich field to study how computational statistics informs what it means to do empirical science. Traditionally held virtues of empirical science and empirical methods like reproducibility, independence, and straightforward observation are complicated by representational choices involved in statistical modeling and data handling. Examining how climate reconstructions instantiate complicated empirical relationships between model, data, and predictions reveals that the path from data to prediction does not match traditional conceptions of empirical inference either. Rather, the empirical inferences involved are "complex" in that they require articulation of a good deal of statistical processing wherein assumptions are adopted and representational decisions made, often in the face of substantial uncertainties. Proxy reconstructions are both statistical and paleoclimate science activities aimed at using a variety of proxies to reconstruct past climate behavior. Paleoclimate proxy reconstructions also involve complex data handling and statistical refinement, leading to the current emphasis in the field on the quantification of uncertainty in reconstructions. In this presentation I explore how the processing needed for the correlation of diverse, large, and messy data sets necessitate the explicit quantification of the uncertainties stemming from wrangling proxies into manageable suites. I also address how semi-empirical pseudo-proxy methods allow for the exploration of signal detection in data sets, and as intermediary steps for statistical experimentation.

Ocean-atmosphere forcing of South American tropical paleoclimate, LGM to present

Science.gov (United States)

Baker, P. A.; Fritz, S. C.; Dwyer, G. S.; Rigsby, C. A.; Silva, C. G.; Burns, S. J.

2012-12-01

Because of many recent terrestrial paleoclimatic and marine paleoceanographic records, late Quaternary South American tropical paleoclimate is as well understood as that anywhere in the world. While lessons learned from the recent instrumental record of climate are informative, this record is too short to capture much of the lower frequency variability encountered in the paleoclimate records and much of the observed paleoclimate is without modern analogue. This paleoclimate is known to be regionally variable with significant differences both north and south of the equator and between the western high Andes and eastern lowlands of the Amazon and Nordeste Brazil. Various extrinsic forcing mechanisms affected climate throughout the period, including global concentrations of GHGs, Northern Hemisphere ice sheet forcing, seasonal insolation forcing of the South American summer monsoon (SASM), millennial-scale Atlantic forcing, and Pacific forcing of the large-scale Walker circulation. The magnitude of the climate response to these forcings varied temporally, largely because of the varying amplitude of the forcing itself. For example, during the last glacial, large-amplitude north Atlantic forcing during Heinrich 1 and the LGM itself, led to wet (dry) conditions south (north) of the equator. During the Holocene, Atlantic forcing was lower amplitude, thus seasonal insolation forcing generally predominated with a weaker-than-normal SASM during the early Holocene resulting in dry conditions in the south-western tropics and wet conditions in the eastern lowlands and Nordeste; in the late Holocene seasonal insolation reached a maximum in the southern tropics and climate conditions reversed.

A 507-year rainfall and runoff reconstruction for the Monsoonal North West, Australia derived from remote paleoclimate archives

Science.gov (United States)

Verdon-Kidd, Danielle C.; Hancock, Gregory R.; Lowry, John B.

2017-11-01

The Monsoonal North West (MNW) region of Australia faces a number of challenges adapting to anthropogenic climate change. These have the potential to impact on a range of industries, including agricultural, pastoral, mining and tourism. However future changes to rainfall regimes remain uncertain due to the inability of Global Climate Models to adequately capture the tropical weather/climate processes that are known to be important for this region. Compounding this is the brevity of the instrumental rainfall record for the MNW, which is unlikely to represent the full range of climatic variability. One avenue for addressing this issue (the focus of this paper) is to identify sources of paleoclimate information that can be used to reconstruct a plausible pre-instrumental rainfall history for the MNW. Adopting this approach we find that, even in the absence of local sources of paleoclimate data at a suitable temporal resolution, remote paleoclimate records can resolve 25% of the annual variability observed in the instrumental rainfall record. Importantly, the 507-year rainfall reconstruction developed using the remote proxies displays longer and more intense wet and dry periods than observed during the most recent 100 years. For example, the maximum number of consecutive years of below (above) average rainfall is 90% (40%) higher in the rainfall reconstruction than during the instrumental period. Further, implications for flood and drought risk are studied via a simple GR1A rainfall runoff model, which again highlights the likelihood of extremes greater than that observed in the limited instrumental record, consistent with previous paleoclimate studies elsewhere in Australia. Importantly, this research can assist in informing climate related risks to infrastructure, agriculture and mining, and the method can readily be applied to other regions in the MNW and beyond.

Phil Wallace and Theoretical Physics at McGill in the 1950's: A Personal Perspective

Energy Technology Data Exchange (ETDEWEB)

Jackson, John David

2010-11-18

In 1946 Philip (Phil) Russell Wallace joined the Mathematics Department of McGill University as an Associate Professor of Applied Mathematics, apparently because A. H. S. Gillson, Dean of Arts and Science, wanted theoretical physicists to be in the Mathematics Department. He came with the dream of creating a theoretical physics group at McGill. By the spring of 1949, Phil was authorized to recruit two junior faculty in Mathematics. He hired Theodore (Ted) F. Morris from U. Toronto, who joined in September 1949, and me, who came in January 1950. The group had begun. Phil Wallace was born in Toronto in 1915 and grew up there. He entered the University of Toronto in 1933, earned a B.A. in mathematics in 1937, a M.A. in 1938, and a Ph.D. in applied mathematics in 1940 under Leopold Infeld. His Ph.D. thesis in general relativity was entitled 'On the relativistic equations of motion in electromagnetic theory.' In 1940 World War II had engulfed Europe and was having its effect on Canada, but the US was still at peace. L. J. Synge, Head of the Applied Mathematics Department at Toronto, told Wallace that people such as he would be needed in war work, but things were not ready quite yet. Hold yourself ready. Phil took a two-year position as lecturer in mathematics at the University of Cincinnati (1940-42); in the fall of 1942 he became a lecturer in mathematics at M.I.T. It was from there that he was recruited by Synge to join the war effort from 1943 to 1946 at N.R.C.'s Montreal Laboratory, the genesis of the Canadian Atomic Energy Project. Phil has described those heady wartime years in these pages. Much of the effort of the theoretical physicists was on nuclear reactor theory and the properties of relevant materials, such as graphite, under long and intense neutron bombardment. In late 1945 Phil was sent for four months to Bristol to learn about the properties of graphite from the esteemed N. F. Mott. This exposure led Phil to a life-long interest in

Effects of McGill stabilization exercises and conventional physiotherapy on pain, functional disability and active back range of motion in patients with chronic non-specific low back pain.

Science.gov (United States)

Ghorbanpour, Arsalan; Azghani, Mahmoud Reza; Taghipour, Mohammad; Salahzadeh, Zahra; Ghaderi, Fariba; Oskouei, Ali E

2018-04-01

[Purpose] The aim of this study was to compare the effects of "McGill stabilization exercises" and "conventional physiotherapy" on pain, functional disability and active back flexion and extension range of motion in patients with chronic non-specific low back pain. [Subjects and Methods] Thirty four patients with chronic non-specific low back pain were randomly assigned to McGill stabilization exercises group (n=17) and conventional physiotherapy group (n=17). In both groups, patients performed the corresponding exercises for six weeks. The visual analog scale (VAS), Quebec Low Back Pain Disability Scale Questionnaire and inclinometer were used to measure pain, functional disability, and active back flexion and extension range of motion, respectively. [Results] Statistically significant improvements were observed in pain, functional disability, and active back extension range of motion in McGill stabilization exercises group. However, active back flexion range of motion was the only clinical symptom that statistically increased in patients who performed conventional physiotherapy. There was no significant difference between the clinical characteristics while compared these two groups of patients. [Conclusion] The results of this study indicated that McGill stabilization exercises and conventional physiotherapy provided approximately similar improvement in pain, functional disability, and active back range of motion in patients with chronic non-specific low back pain. However, it appears that McGill stabilization exercises provide an additional benefit to patients with chronic non-specific low back, especially in pain and functional disability improvement.

A Taxonomic Reduced-Space Pollen Model for Paleoclimate Reconstruction

Science.gov (United States)

Wahl, E. R.; Schoelzel, C.

2010-12-01

Paleoenvironmental reconstruction from fossil pollen often attempts to take advantage of the rich taxonomic diversity in such data. Here, a taxonomically "reduced-space" reconstruction model is explored that would be parsimonious in introducing parameters needing to be estimated within a Bayesian Hierarchical Modeling context. This work involves a refinement of the traditional pollen ratio method. This method is useful when one (or a few) dominant pollen type(s) in a region have a strong positive correlation with a climate variable of interest and another (or a few) dominant pollen type(s) have a strong negative correlation. When, e.g., counts of pollen taxa a and b (r >0) are combined with pollen types c and d (r logistic generalized linear model (GLM). The GLM can readily model this relationship in the forward form, pollen = g(climate), which is more physically realistic than inverse models often used in paleoclimate reconstruction [climate = f(pollen)]. The specification of the model is: rnum Bin(n,p), where E(r|T) = p = exp(η)/[1+exp(η)], and η = α + β(T); r is the pollen ratio formed as above, rnum is the ratio numerator, n is the ratio denominator (i.e., the sum of pollen counts), the denominator-specific count is (n - rnum), and T is the temperature at each site corresponding to a specific value of r. Ecological and empirical screening identified the model (Spruce+Birch) / (Spruce+Birch+Oak+Hickory) for use in temperate eastern N. America. α and β were estimated using both "traditional" and Bayesian GLM algorithms (in R). Although it includes only four pollen types, the ratio model yields more explained variation ( 80%) in the pollen-temperature relationship of the study region than a 64-taxon modern analog technique (MAT). Thus, the new pollen ratio method represents an information-rich, reduced space data model that can be efficiently employed in a BHM framework. The ratio model can directly reconstruct past temperature by solving the GLM equations

Paleoclimate Modeling

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Computer simulations of past climate. Variables provided as model output are described by parameter keyword. In some cases the parameter keywords are a subset of all...

Treating pre-instrumental data as "missing" data: using a tree-ring-based paleoclimate record and imputations to reconstruct streamflow in the Missouri River Basin

Science.gov (United States)

Ho, M. W.; Lall, U.; Cook, E. R.

2015-12-01

Advances in paleoclimatology in the past few decades have provided opportunities to expand the temporal perspective of the hydrological and climatological variability across the world. The North American region is particularly fortunate in this respect where a relatively dense network of high resolution paleoclimate proxy records have been assembled. One such network is the annually-resolved Living Blended Drought Atlas (LBDA): a paleoclimate reconstruction of the Palmer Drought Severity Index (PDSI) that covers North America on a 0.5° × 0.5° grid based on tree-ring chronologies. However, the use of the LBDA to assess North American streamflow variability requires a model by which streamflow may be reconstructed. Paleoclimate reconstructions have typically used models that first seek to quantify the relationship between the paleoclimate variable and the environmental variable of interest before extrapolating the relationship back in time. In contrast, the pre-instrumental streamflow is here considered as "missing" data. A method of imputing the "missing" streamflow data, prior to the instrumental record, is applied through multiple imputation using chained equations for streamflow in the Missouri River Basin. In this method, the distribution of the instrumental streamflow and LBDA is used to estimate sets of plausible values for the "missing" streamflow data resulting in a ~600 year-long streamflow reconstruction. Past research into external climate forcings, oceanic-atmospheric variability and its teleconnections, and assessments of rare multi-centennial instrumental records demonstrate that large temporal oscillations in hydrological conditions are unlikely to be captured in most instrumental records. The reconstruction of multi-centennial records of streamflow will enable comprehensive assessments of current and future water resource infrastructure and operations under the existing scope of natural climate variability.

Pain in workers with shoulder impingement syndrome: an assessment using the DASH and McGill pain questionnaires Dor em trabalhadores portadores da síndrome do impacto do ombro: uma avaliação através dos questionários DASH e McGill de dor

Directory of Open Access Journals (Sweden)

PR Camargo

2007-04-01

Full Text Available OBJECTIVE: This study assessed physical function and pain in male and female workers with shoulder impingement syndrome using the Brazilian Portuguese versions of the Disabilities of the Arm, Shoulder and Hand (DASH and McGill pain questionnaires. METHODS: Twenty-seven assembly line workers (18 men and 9 women; mean age of 33.26 ± 6.49 years in the school supply industry were evaluated. The duration of the shoulder impingement pain was 31.74 ± 32.92 months and the amount of time of the workers in this industry was 11.08 ± 6.41 years. The DASH questionnaire was used to evaluate functional status and symptoms of the upper limbs of the workers. Using the McGill Pain Questionnaire, the pain was quantified by the number of words chosen and by the pain rating index (PRI. RESULTS: The women presented higher scores (POBJETIVO: Este estudo avaliou função física e dor em trabalhadores com síndrome do impacto através das versões brasileiras dos questionários "Disabilities of the Arm, Shoulder and Hand" (DASH e McGill de dor. MÉTODO: Vinte e sete trabalhadores (18 homens e 9 mulheres; idade média de 33,26 ± 6,49 anos de uma linha de produção de uma indústria de material escolar foram avaliados. O tempo de duração de dor no ombro era de 31,74 ± 32,92 meses e o tempo de trabalho na indústria era de 11,08 ± 6,41 anos. O questionário DASH foi utilizado para avaliar o estado funcional e os sintomas dos membros superiores dos trabalhadores. Através do questionário McGill de dor, a dor foi quantificada pelo número de palavras escolhidas e pelo índice de classificação da dor (ICD. RESULTADOS: As mulheres apresentaram maiores escores (P< 0,05 que os homens para ambos os módulos do DASH. As mulheres escolheram mais palavras (17,00 ± 2,59 que os homens (13,33 ± 3,16 e também apresentaram o maior ICD total (P< 0,05. CONCLUSÃO: Os resultados obtidos neste grupo de trabalhadores brasileiros com síndrome do impacto do ombro identificam os

The paleo-climate change of Chaidam Basin during the last 2.85 Ma recorded by gamma-ray logging

International Nuclear Information System (INIS)

Chen Ye; Yuan Linwang; Liu Zechun

2000-01-01

The author deals with mainly the aspect of paleo-climate change of the basin. The approach used for the study consisted of (1) establishing the paleo-climate curve of the basin according to the climate indices, including the spore-pollen statistics, carbonate content and δ 18 O, obtained from the samples of the 760 m continuously-cored exploration holes sited in the basin, (2) comparing the paleo-climate curve with the natural gamma-logs of the same exploration holes, and (3) determining the paleo-climatic changes in the last 2.85 Ma on the basis of detailed geochronological calculations. These results are extremely important for comparison with the δ 18 O-based climate curve derived from the ODP659 in the Atlantic Ocean and with the cycles of paleosol in the Chinese loess

Speleothem Paleoclimate Records from the Floridian Panhandle

Science.gov (United States)

Froelich, P. N.; Kowalczk, A. J.; McCardle, D.; Tibbetts, N.

2007-12-01

Geochemical time-series constructed from speleothem records provide a high resolution view into paleoclimate conditions temporally unmatched by deep ocean sediment and ice core records. The potential of speleothem records is vast with immense spatial and temporal resolution. One surprise to the speleothem paleoclimate community is the absence of high resolution speleothem isotope and trace element records from Florida, an area of extensive karstic geology, a plethora of caves, and monsoon-like climate. Two stalagmites collected from Brooks Quarry Cave, recently opened in Marianna, FL will provide one of the first Holocene speleothem climate records from the Southeast. Speleothem BC-1 is a 71 cm calcite stalagmite collected in situ. Speleothem BC-2 is a 6.1 cm stalagmite collected inside the quarried entrance to the cave. Both dripstones are banded and laminated at what appear to be 11-year cycles (dating in progress). If these are annual "sparves" (speleothem varves), the growth rates are approximately 100 μm per year. BC-1 would extend through much of the Holocene. RGB scans along the polished length of the growth axis reveal color cyclicity related to bundles of these bands. Isotope records from BC-2 reveal a multi-year record showing a variation of -2.7 ‰ to -6 ‰ in δ18O and -3.7 ‰ to -9.1‰ in δ13C, with no correlation between the two. High resolution multi-element laser ablation scans across 8 "sparves" (2.3 mm length) reveals co-variation in U and Ba with other elements showing weaker banding correlations with "clays" (Si, Fe, Mn, Ce, Rb). Photomicrographs of the laser tracks show correlation of visible "sparves" to chemical variations. Medical CT imaging techniques were applied to sample BC-1using a GE Lightspeed Plus CT scanner at maximum power (140 kV, 565 mA) and medium resolution (0.6 mm per scan slice) to view density differences and pore spaces inside the calcite matrix. CT technology reveals a porous nature of the calcite matrix in the lower

The Case for Information Brokering During Major Change: The Experience of the Transition Support Office of the McGill University Health Centre.

Science.gov (United States)

Klag, Malvina; Richer, Marie-Claire

2016-01-01

This paper describes the emergence of an "information brokerage" in the project management office of the McGill University Health Centre (MUHC) in Montreal. This process evolved during unprecedented transformation linked to a redevelopment project. Information brokering became a core function in the MUHC's context of major change. To develop an information brokering model, the paper draws upon the literature on knowledge brokering, applies Daft and Lengel's (1986) seminal framework on information processing in organizations, and builds on the MUHC experience. The paper proposes that knowledge brokering and information brokering are related, yet distinct in content, purpose and structure.

Pangaean climate during the Early Jurassic: GCM simulations and the sedimentary record of paleoclimate

Energy Technology Data Exchange (ETDEWEB)

Chandler, M.A. [Columbia Univ., Palisades, NY (United States); Rind, D.; Ruedy, R. [Goddard Institute for Space Studies, New York, NY (United States)

1992-05-01

Results from new simulations of the Early Jurassic climate show that increased ocean heat transport may have been the primary force generating warmer climates during the past 180 m.y. The simulations, conducted using the general circulation model (GCM) at the Goddard Institute for Space Studies, include realistic representations of paleocontinental distribution, topography, epeiric seas, and vegetation, in order to facilitate comparisons between model results and paleoclimate data. three major features of the simulated Early Jurassic climate include the following. (1) A global warming, compared to the present, of 5 {degrees}C to 10 {degrees}C, with temperature increases at high latitudes five times this global average. Average summer temperatures exceed 35 {degrees}C in low-latitude regions of western Pangaea where eolian sandstones testify to the presence of vast deserts. (2) Simulated precipitation and evaporation patterns agree closely with the moisture distribution interpreted from evaporites, and coal deposits. High rainfall rates are associated primarily with monsoons that originate over the warm Tethys Ocean. Unlike the {open_quotes}megamonsoons{close_quotes} proposed in previous studies, these systems are found to be associated with localized pressure cells whose positions are controlled by topography and coastal geography. (3) Decreases in planetary albedo, occurring because of reductions in sea ice, snow cover, and low clouds, and increases in atmospheric water vapor are the positive climate feedbacks that amplify the global warming. Similar to other Mesozoic climate simulations, our model finds that large seasonal temperature fluctuations occurred over mid- and high-latitude continental interiors, refuting paleoclimate evidence that suggests more equable conditions. 101 refs., 9 figs., 3 tabs.

From Osler's Library to the Osler Library of the History of Medicine, McGill University, Montreal: an overview.

Science.gov (United States)

Lyons, Christopher

2007-01-01

The Osler Library of the History of Medicine was opened in 1929 at McGill University, Montreal, Canada. Sir William Osler (1849-1919), arguably McGill's and Canada's most famous doctor at the time, had bequeathed his magnificent library of almost 8,000 historical works in medicine and, to a lesser extent, science and literature to the university. Under the 30-year reign of its first librarian, Dr. W W. Francis, the Osler Library became famous for its rare books and for its connection with Sir William. Since the 1950s, however, the library has pursued an active collection development policy for both primary and secondary material that has taken it far beyond Osler's original gift. The library has grown in both the size and scope of its holdings and the services it offers to scholars and students of the history of medicine. These have made the Osler Library a major resource centre for studies in the history of the health sciences. This article looks at the Osler Library today in the hopes of making the range of its collections and services better known to the Canadian and international communities.

Revisiting the psychometric properties of a revised Danish version of the McGill ingestive skills assessment

DEFF Research Database (Denmark)

Hansen, Tina; Kristiansen, Dorte Melgaard

2017-01-01

Background: During a longstanding validation process of the Danish version of the McGill Ingestive Skills Assessment (MISA2-DK) for measuring mealtime performance in dysphagic clients, extensive revisions have been undertaken. Therefore, this study aimed to determine the psychometric properties...... of this revised version. Methods: In a cross-sectional study, 328 adults referred to occupational therapy for swallowing evaluation were included. MISA2-DK with 36 items distributed into four subscales (positioning for meals, self-feeding skills, liquid ingestion, and solid ingestion) was administered...

Development of the McGill simulator for endoscopic sinus surgery: a new high-fidelity virtual reality simulator for endoscopic sinus surgery.

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Varshney, Rickul; Frenkiel, Saul; Nguyen, Lily H P; Young, Meredith; Del Maestro, Rolando; Zeitouni, Anthony; Tewfik, Marc A

2014-01-01

The technical challenges of endoscopic sinus surgery (ESS) and the high risk of complications support the development of alternative modalities to train residents in these procedures. Virtual reality simulation is becoming a useful tool for training the skills necessary for minimally invasive surgery; however, there are currently no ESS virtual reality simulators available with valid evidence supporting their use in resident education. Our aim was to develop a new rhinology simulator, as well as to define potential performance metrics for trainee assessment. The McGill simulator for endoscopic sinus surgery (MSESS), a new sinus surgery virtual reality simulator with haptic feedback, was developed (a collaboration between the McGill University Department of Otolaryngology-Head and Neck Surgery, the Montreal Neurologic Institute Simulation Lab, and the National Research Council of Canada). A panel of experts in education, performance assessment, rhinology, and skull base surgery convened to identify core technical abilities that would need to be taught by the simulator, as well as performance metrics to be developed and captured. The MSESS allows the user to perform basic sinus surgery skills, such as an ethmoidectomy and sphenoidotomy, through the use of endoscopic tools in a virtual nasal model. The performance metrics were developed by an expert panel and include measurements of safety, quality, and efficiency of the procedure. The MSESS incorporates novel technological advancements to create a realistic platform for trainees. To our knowledge, this is the first simulator to combine novel tools such as the endonasal wash and elaborate anatomic deformity with advanced performance metrics for ESS.

Paleoclimate Reconstruction during the 17th to 18th Century Using Fossil Coral Tsunami Boulders from Ishigaki Island, the Ryukyus, Japan

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Tsuzuki, K.; Yokoyama, Y.; Seki, A.; Kawakubo, Y.; Araoka, D.; Suzuki, A.

2014-12-01

Little Ice Age (LIA) which lasted during approximately 1450 to 1850 (e.g. Grove, 1988) is known as naturally occurring climate fluctuation, so knowing LIA in detail is necessary to improve climate models. Instrumental records can only extend back to about 100 years in many areas, thus paleoclimate records are reconstructed using proxies in tree rings, sediments and so force. However there are differences in reconstructed timings and magnitudes of LIA occurred in each area (Overpack et al., 1997), and most of the records are based mainly on terrestrial proxies such as tree ring records, whereas only limited numbers of marine records are available (Mann et al., 2008). Coral skeletal climatology is a useful tool to reconstruct marine paleoclimate records in tropics and subtropics. Hermatypic corals, Porites spp. have aragonite skeletons and they have annual bands, which are suitable to reconstruct high-resolution paleoclimate in seasonal scale by measuring chemical compositions. Skeletal Sr/Ca ratio in Porites spp. has been widely used as a reliable proxy of SST (Sea Surface Temperature). However, corals grow for approximately several decades to 200 years, hence it is difficult to reconstruct LIA paleoclimate using living corals. Cobb et al. (2003) used fossil corals casted on shore by storms to reconstruct millennial scale paleoclimate. There are fossil coral boulders in the eastern coast of Ishigaki Island, Ryukyus, Japan. These fossil coral boulders were casted on shore by paleo Tsunami events, thus they are called "Tsunami boulders" (Araoka et al., 2010). Fossil corals used by Cobb et al. have 30-90-year records while some large Tsunami boulders have multi-centennial continuous records. In this study, we reconstruct paleo SST using the Tsunami boulder from Ishigaki Island. The boulder has 185 years of annual banding. U-series dating shows the boulder was moved on shore at Meiwa earthquake in 1771. We measure Sr/Ca ratio using LA-HR-ICPMS (Laser Ablation High

The Brazilian Northeastern paleoclimate according to the isotope hydrology

International Nuclear Information System (INIS)

Frischkorn, Horst; Santiago, Maria Marlucia Freitas

1992-01-01

This work interprets measures in deep well waters of the Serra Grande aquifer from the Piaui State. It uses the temperature and quantity effects on the oxygen isotopic composition in the pluvial water, together the noble gases analysis dissolved in water and 14 C dating in the bicarbonates to establish a time scale, aiming to reconstruct the Brazil Northeastern region paleoclimate at the Pleistocene final era, as well as to elucidate the hydric resources formation conditions (that date from this epoch) in the deep aquifers of the region sedimentary basins

Autogenic geomorphic processes determine the resolution and fidelity of terrestrial paleoclimate records.

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Foreman, Brady Z; Straub, Kyle M

2017-09-01

Terrestrial paleoclimate records rely on proxies hosted in alluvial strata whose beds are deposited by unsteady and nonlinear geomorphic processes. It is broadly assumed that this renders the resultant time series of terrestrial paleoclimatic variability noisy and incomplete. We evaluate this assumption using a model of oscillating climate and the precise topographic evolution of an experimental alluvial system. We find that geomorphic stochasticity can create aliasing in the time series and spurious climate signals, but these issues are eliminated when the period of climate oscillation is longer than a key time scale of internal dynamics in the geomorphic system. This emergent autogenic geomorphic behavior imparts regularity to deposition and represents a natural discretization interval of the continuous climate signal. We propose that this time scale in nature could be in excess of 10 4 years but would still allow assessments of the rates of climate change at resolutions finer than the existing age model techniques in isolation.

Estudo comparativo de simulações paleoclimáticas na região do Atlântico Sul Comparison of paleoclimatics simulation in the South Atlantic region

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Adriana Oliveira

2007-04-01

Full Text Available Neste estudo são comparadas diferentes simulações de modelos paleoclimáticos para duas épocas distintas, o Último Máximo Glacial (UMG e o Presente. Esta comparação visa elucidar as principais diferenças nos processos físicos e dinâmicos do sistema oceano-atmosfera na região do oceano Atlântico Sul entre estes dois períodos. Foram analisadas as variações na climatologia anual entre estas épocas para os seguintes parâmetros: temperatura do ar (TA, precipitação (PPT e pressão ao nível do mar (PNM. As simulações numéricas analisadas são do projeto PMIP (Paleoclimate Modelling Intercomparison Project e do modelo numérico acoplado NCAR (National Center for Atmospheric Research CCSM (Comunnity Climate System Model versão 1.4 nos dois períodos de interesse. Os resultados mostram uma intensificação do presente em relação ao UMG em todas as variáveis analisadas. As diferentes simulações atmosféricas do PMIP apresentaram padrões consistentes com os apresentados no modelo NCAR CCSM, sendo observados baixos valores de EQM (Erro Quadrático Médio para grande parte da região de estudo.The present work presents a comparison between the results of different paleoclimate simulations models for two periods, the Last Glacial Maximum (LGM and the Present day. This comparison intents to elucidate the overall differences of the physical and dynamical processes from ocean-atmosphere system for these two climates. We analyzed the variations in the annual climatology between the LGM and Present for the following variables: air temperature, precipitation and sea level pressure. We used the results of the PMIP (Paleoclimate Modelling Intercomparison Project and the numerical coupled model developed at NCAR (National Center for Atmospheric Research CCSM (Comunnity Climate System Model for the two periods of interest. The results show an intensification of the present in relation to the LGM in all variables. The different atmospheric

Patterns and timing of loess-paleosol transitions in Eurasia: Constraints for paleoclimate studies

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Zeeden, Christian; Hambach, Ulrich; Obreht, Igor; Hao, Qingzhen; Abels, Hemmo A.; Veres, Daniel; Lehmkuhl, Frank; Gavrilov, Milivoj B.; Marković, Slobodan B.

2018-03-01

Loess-paleosol sequences are the most extensive terrestrial paleoclimate records in Europe and Asia documenting atmospheric circulation patterns, vegetation, and sedimentary dynamics in response to glacial-interglacial cyclicity. Between the two sides of the Eurasian continent, differences may exist in response and response times to glacial changes and finding these is essential to understand the climate systems of the northern hemisphere. Therefore, assessment of common patterns and regional differences in loess-paleosol sequences (LPS) is vital, but remains, however, uncertain. Another key to interpret these records is to constrain the mechanisms responsible for the formation and preservation of paleosols and loess layers in these paleoclimate archives. This study therefore compares LPS magnetic susceptibility records as proxies for paleosol formation intensity for selected sites from the central Chinese Loess Plateau and the Carpathian Basin in Europe over the last 440 kyr. Inconsistencies and crucial issues concerning the timing, correlation and paleoclimate potential of selected Eurasian LPS are outlined. Our comparison of Eurasian LPS shows generally similar patterns of paleosol formation, while highlighting several crucial differences. Especially for paleosols developed around 200 and 300 ka, the reported timing of soil formation differs by up to 30 ka. In addition, a drying and cooling trend over the last 300 ka has been documented in Europe, with no such evidence in the Asian records. The comparison shows that there is still uncertainty in defining the chronostratigraphic framework for these records on glacial-interglacial time scales in the order of 5-30 kyr for the last 440 ka. We argue that the baseline of the magnetic susceptibility proxy in loess from the Carpathian Basin is the most striking difference between European LPS and the Chinese Loess Plateau. In our opinion, many of the current timing/age differences may be overcome once a comparable

Kinetostatic and Inertial Conditioning of the McGill Schönflies-Motion Generator

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Alessandro Cammarata

2010-01-01

Full Text Available This paper focuses on the optimization of the McGill Schönflies Motion Generator. Recent trends on optimum design of parallel robots led us to investigate the advantages and disadvantages derived from an optimization based on performance indices. Particularly, we optimize here two different indices: the kinematic conditioning and the inertial conditioning, pertaining to the condition number of the Jacobian matrix and to that of the generalized inertia matrix of the robot, respectively. The problem of finding the characteristic length for the robot is first investigated by means of a constrained optimization problem; then plots of the kinetostatic and the inertial conditioning indices are provided for a particular trajectory to be tracked by the moving platform of the SMG. Deep connections appear between the two indices, reflecting a correlation between kinematics and dynamics.

Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

Energy Technology Data Exchange (ETDEWEB)

Dubiel, R.F. (Geological Survey, Denver, CO (USA))

1989-09-01

Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

Validation of a New Questionnaire with Generic and Disease-Specific Qualities: The Mcgill Copd Quality of Life Questionnaire

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Smita Pakhale

2012-01-01

Full Text Available BACKGROUND: A validated health-related quality of life questionnaire in chronic obstructive pulmonary disease (COPD with advantages of both generic- and disease-specific questionnaires is needed to capture patients’ perspectives of severity and impact of the disease. The McGill COPD questionnaire was created to include these advantages in English and French. It assesses three domains: symptoms, physical function and feelings with 29 items (12 from the 36-item Short-Form Health Survey with 17 from the previously developed COPD-specific module.

Paleoclimate from fossil plants and application to the early Cenozoic Rocky Mountains

Science.gov (United States)

Wing, S. L.

2011-12-01

Wladimir Köppen called vegetation "crystallized, visible climate," and his metaphor encouraged paleobotanists to climb the chain of inference from fossil plants to paleovegetation to paleoclimate. Inferring paleovegetation from fossils has turned out to be very difficult, however, and today most paleobotanical methods for inferring paleoclimate do not try to reconstruct paleovegetation as a first step. Three major approaches are widely use to infer paleoclimate from plant fossils: 1) phylogenetic inferences rely on the climatic distributions of extant relatives of fossils, 2) morphological inferences use present-day correlations of climate with plant morphology (e.g, leaf shape, wood anatomy), and 3) chemical inferences rely on correlations between climate and the stable isotopic composition of plants or organic compounds. Each approach makes assumptions that are hard to verify. Phylogenetic inference depends on accurate identification of fossils, and also assumes that evolution and/or extinction has not shifted the climatic distributions of plant lineages through time. On average this assumption is less valid for older time periods, but probably it is not radically wrong for the early Cenozoic. Morphological approaches don't require taxonomic identification of plant fossils, but do assume that correlations between plant form and climate have been constant over time. This assumption is bolstered if the ecophysiological cause of the morphology-climate correlation is well understood, but often it isn't. Stable isotopic approaches assume that present-day correlations between isotopic composition and climate apply to the past. Commonly the chemical and physiological mechanisms responsible for the correlation are moderately well known, but often the variation among different taxonomic and functional groups of plants is poorly characterized. In spite of limitations and uncertainties on all methods for inferring paleoclimate from fossil plants, broad patterns emerge from

Objectively combining AR5 instrumental period and paleoclimate climate sensitivity evidence

Science.gov (United States)

Lewis, Nicholas; Grünwald, Peter

2018-03-01

Combining instrumental period evidence regarding equilibrium climate sensitivity with largely independent paleoclimate proxy evidence should enable a more constrained sensitivity estimate to be obtained. Previous, subjective Bayesian approaches involved selection of a prior probability distribution reflecting the investigators' beliefs about climate sensitivity. Here a recently developed approach employing two different statistical methods—objective Bayesian and frequentist likelihood-ratio—is used to combine instrumental period and paleoclimate evidence based on data presented and assessments made in the IPCC Fifth Assessment Report. Probabilistic estimates from each source of evidence are represented by posterior probability density functions (PDFs) of physically-appropriate form that can be uniquely factored into a likelihood function and a noninformative prior distribution. The three-parameter form is shown accurately to fit a wide range of estimated climate sensitivity PDFs. The likelihood functions relating to the probabilistic estimates from the two sources are multiplicatively combined and a prior is derived that is noninformative for inference from the combined evidence. A posterior PDF that incorporates the evidence from both sources is produced using a single-step approach, which avoids the order-dependency that would arise if Bayesian updating were used. Results are compared with an alternative approach using the frequentist signed root likelihood ratio method. Results from these two methods are effectively identical, and provide a 5-95% range for climate sensitivity of 1.1-4.05 K (median 1.87 K).

Ice Melt, Sea Level Rise and Superstorms: Evidence from Paleoclimate Data, Climate Modeling, and Modern Observations that 2C Global Warming Could Be Dangerous

Science.gov (United States)

Hansen, J.; Sato, Makiko; Hearty, Paul; Ruedy, Reto; Kelley, Maxwell; Masson-Delmotte, Valerie; Russell, Gary; Tselioudis, George; Cao, Junji; Rignot, Eric;

Two Decades of Funded Research Goals and Achievements on Inquiry by the High Ability and Inquiry Research Group (HAIR) at McGill University

Science.gov (United States)

Gube, Maren; Shore, Bruce M.

2018-01-01

From the 1990s until 2017 the High Ability and Inquiry Research Group (HAIR) at McGill University in Montreal, received C$1.3M in research funds from Canadian, Quebec, and US agencies to support its research and graduate training in education and educational psychology. Their research encompassed two principal areas, Inquiry in Education and…

Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous

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J. Hansen

2016-03-01

while Earth was less than 1 °C warmer than today. Ice melt cooling of the North Atlantic and Southern oceans increases atmospheric temperature gradients, eddy kinetic energy and baroclinicity, thus driving more powerful storms. The modeling, paleoclimate evidence, and ongoing observations together imply that 2 °C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1 cooling of the Southern Ocean, especially in the Western Hemisphere; (2 slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3 slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4 increasingly powerful storms; and (5 nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.

Comparison of the Effect of Dry Cupping Therapy and Acupressure at BL23 Point on Intensity of Postpartum Perineal Pain Based on the Short Form of McGill Pain Questionnaire.

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Akbarzade, Marzieh; Ghaemmaghami, Mehrnoush; Yazdanpanahi, Zahra; Zare, Najaf; Mohagheghzadeh, Abdolali; Azizi, Amir

2016-01-01

Perineal pain is a major morbidity in the first few days after delivery. This study aimed to investigate the effect of dry cupping therapy and acupressure at BL23 point on the intensity of postpartum perineal pain based on the short-form of McGill pain questionnaire (SMPQ). The present clinical trial was conducted on 150 subjects in 3 groups of 50 cases. After at least 4-8 hr of delivery, cupping therapy was performed for 15-20 min up to 3 times a week (once a day) and acupressure was performed for 15-20 min based on clockwise model. The short-form of McGill pain questionnaire was completed both before and after the intervention. The SPSS statistical software was used to analyze the data using repeated measures ANOVA. Besides, pcupping therapy group, mean of the perineal pain intensity reduced from 37.5±6.8 before the intervention to 11.1±6.1, 6.9±4.7, and 3.8±3.6 immediately, 24 hr, and 2 weeks after the intervention, respectively. The results of study showed that the differences between the intervention and control groups were statistically significant (pcupping therapy and acupressure reduced perineal pain. Therefore, they may be considered as effective treatments for reducing pain intensity of allowing delivery.

Coupled hydromechanical paleoclimate analyses of density-dependant groundwater flow in discretely fractured crystalline rock settings

Science.gov (United States)

Normani, S. D.; Sykes, J. F.; Jensen, M. R.

2009-04-01

A high resolution sub-regional scale (84 km2) density-dependent, fracture zone network groundwater flow model with hydromechanical coupling and pseudo-permafrost, was developed from a larger 5734 km2 regional scale groundwater flow model of a Canadian Shield setting in fractured crystalline rock. The objective of the work is to illustrate aspects of regional and sub-regional groundwater flow that are relevant to the long-term performance of a hypothetical nuclear fuel repository. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture zone network model delineated from surface features was superimposed onto an 789887 element flow domain mesh. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. The crystalline rock between these structural discontinuities was assigned properties characteristic of those reported for the Canadian Shield at the Underground Research Laboratory at Pinawa, Manitoba. Interconnectivity of permeable fracture features is an important pathway for the possibly relatively rapid migration of average water particles and subsequent reduction in residence times. The multiple 121000 year North American continental scale paleoclimate simulations are provided by W.R. Peltier using the University of Toronto Glacial Systems Model (UofT GSM). Values of ice sheet normal stress, and proglacial lake depth from the UofT GSM are applied to the sub-regional model as surface boundary conditions, using a freshwater head equivalent to the normal stress imposed by the ice sheet at its base. Permafrost depth is applied as a permeability reduction to both three-dimensional grid blocks and fractures that lie within the time varying permafrost zone. Two different paleoclimate simulations are applied to the sub-regional model to investigate the effect on the depth of glacial meltwater migration into the subsurface. In

Carbon, hydrogen oxygen isotope studies on imbedded old tree ring and paleoclimate reconstruction

International Nuclear Information System (INIS)

Sun Yanrong; Mu Zhiguo; Cui Haiting

2002-01-01

Tree ring is a kind of natural archives, on which the isotopic analysis is important to study global climate and environmental change. The authors mainly provide a comprehensive introduction to the fractionation models of carbon, hydrogen and oxygen isotope in plants, their research technique and the extract methods from cellulose. That results show isotopic tracer can record the message of climatic variation and has become a powerful tool for paleoclimate reconstruction and for the modern environment changing research. Especially studying on PAGES. the cellulose isotopic analyses of imbedded old tree ring have become the mainly quantitative means of environmental evolvement. In addition, China is a typical monsoon country, research in tree ring stable isotope seasonal variation can give a lot of important information on that. Up to now, the research techniques and works on tree ring in China are still in its earlier stage, and remain many limitations. It needs further accumulate basic research materials, intensity regional contrast and intercross studies on relative subjects

The paleoclimate of the Kazanian (early Late Permian) world

Energy Technology Data Exchange (ETDEWEB)

Moore, G.T. (Chevron Oil Field Research Co., La Habra, CA (USA)); Peoples, C.J. (Texas A and M Univ., College Station (USA))

1990-05-01

The Kazanian (early Late Permian, 258-253 m.y.) marked the onset of a unique interval in the Phanerozoic, distinguished by a classic end-member case of continental assembly, the megacontinent Pangaea. Compilation of biostratigraphic and lithofacies data indicate a warm, extensively arid world, largely ice free, and characterized by the onset of atmospheric conditions that were exceedingly stressful to the biosphere, the worst of the eon. Using Chevron's version of the Community Climate model, the authors report here on two Kazanian paleoclimate seasonal simulations, one using 200 ppm CO{sub 2} and the other with 2,000 ppm CO{sub 2}. The authors consider the knowledge of plate assembly back to the Permian accurate enough to allow employment of a seasonal model. Simulation of a warmer Earth with an elevated greenhouse effect (modeled as CO{sub 2}) fits the observed geology and isotope signals. The increased CO{sub 2} experiment warmed the entire planet with the greatest increases north of 50{degree} latitude and least changes in the tropics. The warming caused the poleward retreat of sea ice in both hemispheres. Precipitation and evaporation increased, but runoff was confined to areas of very intense rainfall. Monsoons are limited to the southern hemisphere, associated with the western Tethys sea and the eastern equatorial Panthalassa ocean. Extreme southeastern Pangaea (northern Australia) was a focus of precipitation throughout the year. Precipitation occurred in the higher latitudes (50-55{degree}) on the western coast, of Pangaea where storm tracks make landfall. High evaporation rates characterized the restricted Permian (US), Zechstein, and Perm (Soviet Union) basins, a time of evaporite, deposition. Interior Pangaea at middle to high latitudes endured frigid winters ({minus}40{degree}C) and torrid summers (60{degree}C).

A Paleolatitude Calculator for Paleoclimate Studies.

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Douwe J J van Hinsbergen

Full Text Available Realistic appraisal of paleoclimatic information obtained from a particular location requires accurate knowledge of its paleolatitude defined relative to the Earth's spin-axis. This is crucial to, among others, correctly assess the amount of solar energy received at a location at the moment of sediment deposition. The paleolatitude of an arbitrary location can in principle be reconstructed from tectonic plate reconstructions that (1 restore the relative motions between plates based on (marine magnetic anomalies, and (2 reconstruct all plates relative to the spin axis using a paleomagnetic reference frame based on a global apparent polar wander path. Whereas many studies do employ high-quality relative plate reconstructions, the necessity of using a paleomagnetic reference frame for climate studies rather than a mantle reference frame appears under-appreciated. In this paper, we briefly summarize the theory of plate tectonic reconstructions and their reference frames tailored towards applications of paleoclimate reconstruction, and show that using a mantle reference frame, which defines plate positions relative to the mantle, instead of a paleomagnetic reference frame may introduce errors in paleolatitude of more than 15° (>1500 km. This is because mantle reference frames cannot constrain, or are specifically corrected for the effects of true polar wander. We used the latest, state-of-the-art plate reconstructions to build a global plate circuit, and developed an online, user-friendly paleolatitude calculator for the last 200 million years by placing this plate circuit in three widely used global apparent polar wander paths. As a novelty, this calculator adds error bars to paleolatitude estimates that can be incorporated in climate modeling. The calculator is available at www.paleolatitude.org. We illustrate the use of the paleolatitude calculator by showing how an apparent wide spread in Eocene sea surface temperatures of southern high

The biogeophysical effects of extreme afforestation in modeling future climate

Science.gov (United States)

Wang, Ye; Yan, Xiaodong; Wang, Zhaomin

2014-11-01

Afforestation has been deployed as a mitigation strategy for global warming due to its substantial carbon sequestration, which is partly counterbalanced with its biogeophysical effects through modifying the fluxes of energy, water, and momentum at the land surface. To assess the potential biophysical effects of afforestation, a set of extreme experiments in an Earth system model of intermediate complexity, the McGill Paleoclimate Model-2 (MPM-2), is designed. Model results show that latitudinal afforestation not only has a local warming effect but also induces global and remote warming over regions beyond the forcing originating areas. Precipitation increases in the northern hemisphere and decreases in southern hemisphere in response to afforestation. The local surface warming over the forcing originating areas in northern hemisphere is driven by decreases in surface albedo and increases in precipitation. The remote surface warming in southern hemisphere is induced by decreases in surface albedo and precipitation. The results suggest that the potential impact of afforestation on regional and global climate depended critically on the location of the forest expansion. That is, afforestation in 0°-15°N leaves a relatively minor impact on global and regional temperature; afforestation in 45°-60°N results in a significant global warming, while afforestation in 30°-45°N results in a prominent regional warming. In addition, the afforestation leads to a decrease in annual mean meridional oceanic heat transport with a maximum decrease in forest expansion of 30°-45°N. These results can help to compare afforestation effects and find areas where afforestation mitigates climate change most effectively combined with its carbon drawdown effects.

The Power of Cooperation in International Paleoclimate Science: Examples from the PAGES 2k Network and the Ocean2k Working Group

Science.gov (United States)

Addison, J. A.

2015-12-01

The Past Global Changes (PAGES) project of IGBP and Future Earth supports research to understand the Earth's past environment to improve future climate predictions and inform strategies for sustainability. Within this framework, the PAGES 2k Network was established to provide a focus on the past 2000 years, a period that encompasses Medieval Climate Anomaly warming, Little Ice Age cooling, and recent anthropogenically-forced climate change. The results of these studies are used for testing earth system models, and for understanding decadal- to centennial-scale variability, which is needed for long-term planning. International coordination and cooperation among the nine regional Working Groups that make up the 2k Network has been critical to the success of PAGES 2k. The collaborative approach is moving toward scientific achievements across the regional groups, including: (i) the development of a community-driven open-access proxy climate database; (ii) integration of multi-resolution proxy records; (iii) development of multivariate climate reconstructions; and (iv) a leap forward in the spatial resolution of paleoclimate reconstructions. The last addition to the 2k Network, the Ocean2k Working Group has further innovated the collaborative approach by: (1) creating an open, receptive environment to discuss ideas exclusively in the virtual space; (2) employing an array of real-time collaborative software tools to enable communication, group document writing, and data analysis; (3) consolidating executive leadership teams to oversee project development and manage grassroots-style volunteer pools; and (4) embracing the value-added role that international and interdisciplinary science can play in advancing paleoclimate hypotheses critical to understanding future change. Ongoing efforts for the PAGES 2k Network are focused on developing new standards for data quality control and archiving. These tasks will provide the foundation for new and continuing "trans-regional" 2k

Sensitivity analysis of a coupled hydro-mechanical paleo-climate model of density-dependent groundwater flow in discretely fractured crystalline rock

International Nuclear Information System (INIS)

Normani, S.D.; Sykes, J.F.

2011-01-01

A high resolution three-dimensional sub-regional scale (104 km 2 ) density-dependent, discretely fractured groundwater flow model with hydro-mechanical coupling and pseudo-permafrost was developed from a larger 5734 km 2 regional-scale groundwater flow model of a Canadian Shield setting. The objective of the work is to determine the sensitivity of modelled groundwater system evolution to the hydro-mechanical parameters. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture network model delineated from surface features was superimposed onto an approximate 790 000 element domain mesh with approximately 850 000 nodes. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. Interconnectivity of the permeable fracture zones is an important pathway for the possible migration and subsequent reduction in groundwater and contaminant residence times. The crystalline rock matrix between these structural discontinuities was assigned mechanical and flow properties characteristic of those reported for the Canadian Shield. The variation of total dissolved solids with depth was assigned using literature data for the Canadian Shield. Performance measures for the sensitivity analysis include equivalent freshwater heads, environmental heads, linear velocities, and depth of penetration by conservative non-decaying tracers released at the surface. A 121 000 year North American continental scale paleo-climate simulation was applied to the domain with ice-sheet histories estimated by the University of Toronto Glacial Systems Model (UofT GSM). Hydro-mechanical coupling between the rock matrix and the pore fluid, due to the ice sheet normal stress, was included in the simulations. The flow model included the influence of vertical strain and assumed that areal loads were homogeneous. Permafrost depth was applied as a permeability reduction

Glacial Isostatic Adjustment Derived Boundary Conditions for Paleoclimate Simulation: the Refined ICE-6G_D (VM5a) Model and the Dansgaard-Oeschger Oscillation

Science.gov (United States)

Peltier, W. R.; Vettoretti, G.; Argus, D. F.

2017-12-01

Global models of the glacial isostatic adjustment (GIA) process are designed to fit a wide range of geophysical and geomorphological observations that simultaneously constrain the internal viscoelastic structure of Earths interior and the history of grounded ice thickness variations that has occurred over the most recent ice-age cycle of the Late Quaternary interval of time. The most recent refinement of the ICE-NG (VMX) series of such global models from the University of Toronto, ICE-6G_C (VM5a), has recently been slightly modified insofar as its Antarctic component is concerned to produce a "_D" version of the structure. This has been chosen to provide the boundary conditions for the next round of model-data inter-comparisons in the context of the international Paleoclimate Modeling Inter-comparison Project (PMIP). The output of PMIP will contribute to the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change which is now under way. A highly significant test of the utility of this latest model has recently been performed that is focused upon the Dansgaard-Oeschger oscillation that was the primary source of climate variability during Marine Isotope Stage 3 (MIS3) of the most recent glacial cycle. By introducing the surface boundary conditions for paleotopography and paleobathymetry, land-sea mask and surface albedo into the NCAR CESM1 coupled climate model configured at full one degree by one degree CMIP5 resolution, together with the appropriate trace gas and orbital insolation forcing, we show that the millennium timescale Dansgard-Oeschger oscillation naturally develops following spin- up of the model into the glacial state.

[Climate implications of terrestrial paleoclimate]. Quaternary Sciences Center, Desert Research Institute annual report, fiscal year 1994/1995

International Nuclear Information System (INIS)

Wigand, P.E.

1995-01-01

The objective of this study is to collect terrestrial climate indicators for paleoclimate synthesis. The paleobiotic and geomorphic records are being examined for the local and regional impact of past climates to assess Yucca Mountain's suitability as a high-level nuclear waste repository. In particular these data are being used to provide estimates of the timing, duration and extremes of past periods of moister climate for use in hydrological models of local and regional recharge that are being formulated by USGS and other hydrologists for the Yucca Mountain area. The project includes botanical, faunal, and geomorphic components that will be integrated to accomplish this goal. To this end personnel at the Quaternary Sciences Center of the Desert Research Institute in Reno, Nevada are conducting the following activities: Analyses of packrat middens; Analysis of pollen samples; and Determination of vegetation climate relationships

A national perspective on paleoclimate streamflow and water storage infrastructure in the conterminous United States

Science.gov (United States)

Ho, Michelle; Lall, Upmanu; Sun, Xun; Cook, Edward

2017-04-01

Large-scale water storage infrastructure in the Conterminous United States (CONUS) provides a means of regulating the temporal variability in water supply with storage capacities ranging from seasonal storage in the wetter east to multi-annual and decadal-scale storage in the drier west. Regional differences in water availability across the CONUS provides opportunities for optimizing water dependent economic activities, such as food and energy production, through storage and transportation. However, the ability to sufficiently regulate water supplies into the future is compromised by inadequate monitoring of non-federally-owned dams that make up around 97% of all dams. Furthermore, many of these dams are reaching or have exceeded their economic design life. Understanding the role of dams in the current and future landscape of water requirements in the CONUS is needed to prioritize dam safety remediation or identify where redundant dams may be removed. A national water assessment and planning process is needed for addressing water requirements, accounting for regional differences in water supply and demand, and the role of dams in such a landscape. Most dams in the CONUS were designed without knowledge of devastating floods and prolonged droughts detected in multi-centennial paleoclimate records, consideration of projected climate change, nor consideration of optimal operation across large-scale regions. As a step towards informing water supply across the CONUS we present a paleoclimate reconstruction of annual streamflow across the CONUS over the past 555 years using a spatially and temporally complete paleoclimate record of summer drought across the CONUS targeting a set of US Geological Survey streamflow sites. The spatial and temporal structures of national streamflow variability are analyzed using hierarchical clustering, principal component analysis, and wavelet analyses. The reconstructions show signals of contemporary droughts such as the Dust Bowl (1930s

An isotopic and modelling study of flow paths and storage in Quaternary calcarenite, SW Australia: implications for speleothem paleoclimate records

Science.gov (United States)

Treble, Pauline C.; Bradley, Chris; Wood, Anne; Baker, Andy; Jex, Catherine N.; Fairchild, Ian J.; Gagan, Michael K.; Cowley, Joan; Azcurra, Cecilia

2013-03-01

We investigated the distinctive shallow sub-surface hydrology of the southwest Western Australia (SWWA) dune calcarenite using observed rainfall and rainfall δ18O; soil moisture, cave drip rate and dripwater δ18O over a six-year period: August 2005-March 2012. A lumped parameter hydrological model is developed to describe water fluxes and drip δ18O. Comparison of observed data and model output allow us to assess the critical non-climatic karst hydrological processes that modify the precipitation δ18O signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting. Our findings include evidence of multiple reservoirs, characterised by distinct δ18O values and recharge responses ('low' and 'high' flow sites). Dripwaters exhibit δ18O variations in wet versus dry years at low-flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall. Recharge from high-magnitude rain events is stored in a secondary reservoir which is associated with high-flow dripwater that is 1‰ lower than our monitored low-flow sites (δ18O). One drip site is characterised by mixed-flow behaviour and exhibits a non-linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year (2006). Additionally, our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in Quaternary age dune limestones. We show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year. Diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock.

The sedimentary record and petrophysical logs from the Spanish Central Pyrenees: Implications for paleoclimate change in the Early Devonian

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

2015-01-01

Roč. 21, - (2015), s. 350-350 ISSN 1608-8166. [International Congress on Stratigraphy /2./. STRATI 2015. 19.07.2015-23.07.2015, Graz] Institutional support: RVO:67985831 Keywords : stratigraphy * Early Devonian * sedimentary record * paleoclimate change * Spanish Central Pyrenees Subject RIV: DB - Geology ; Mineralogy http://www.zobodat.at/pdf/Ber-Inst-Erdwiss-Univ-Graz_21_0001-0437.pdf

The McGill Interactive Pediatric OncoGenetic Guidelines: An approach to identifying pediatric oncology patients most likely to benefit from a genetic evaluation.

Science.gov (United States)

Goudie, Catherine; Coltin, Hallie; Witkowski, Leora; Mourad, Stephanie; Malkin, David; Foulkes, William D

2017-08-01

Identifying cancer predisposition syndromes in children with tumors is crucial, yet few clinical guidelines exist to identify children at high risk of having germline mutations. The McGill Interactive Pediatric OncoGenetic Guidelines project aims to create a validated pediatric guideline in the form of a smartphone/tablet application using algorithms to process clinical data and help determine whether to refer a child for genetic assessment. This paper discusses the initial stages of the project, focusing on its overall structure, the methodology underpinning the algorithms, and the upcoming algorithm validation process. © 2017 Wiley Periodicals, Inc.

[Dante's Inferno and the McGill Pain Questionnaire].

Science.gov (United States)

Tonelli, N; Marcolongo, R

2007-01-01

To study the images which depict the damned's sufferings in Dante's Inferno, in their expression of the several meanings of "pain", the semantics of "pain" in the poem has been analyzed, eventually trying to determine whether the organization of punishments of Inferno may somehow mirror a disability scale. A detailed analysis of the text was carried out, which proved a valuable tool for interpreting the organization of punishments as a possible disability scale. The semantics of pain in the Divine Comedy was studied through all the forms of the pain descriptors (included the archaic terminological forms) from the Italian version of the McGill Pain Questionnaire (MGPQ) by Maiani and Sanavio. In Dante's Inferno a classification of pain is provided, based on the experience of sufferings; Dante's images seem not only instrumental to investigating the sensorial but also the affective and intellectual spheres by introducing a number of characters and describing the impact of punishment onto their souls. Our research highlighted that 46 out of 78 terms from the MGPQ are present in Inferno, though with different forms; the Groups the MGPQ is divided into are also represented with the exception of Group XII, the most frequently detected being Groups XIII-which studies the fear-related sensations in the emotional sphere - XIV, XIX and XX. The great attention emerges that Dante devoted to describing simple sensorial experiences as well as the way punishments affected the soul. As a whole, the terms pertaining to the sensorial sphere are the most frequently encountered. The lack of motion which increases circle after circle in Hell, well matches the progressing physical and psychological impairment caused by some invalidating diseases. Noticeably, Dante created such a complex system centuries before the studies were released on the impact of pain and its quantitative and mostly qualitative definition. In conclusion, this interpretation suggests that the writing on the door to

Petrography and stable isotope geochemistry of Oligocene-Miocene continental carbonates in south Texas: Implications for paleoclimate and paleoenvironment near sea-level

Science.gov (United States)

Godfrey, Conan; Fan, Majie; Jesmok, Greg; Upadhyay, Deepshikha; Tripati, Aradhna

2018-05-01

Cenozoic sedimentary rocks in the southern Texas Gulf Coastal Plains contain abundant continental carbonates that are useful for reconstructing terrestrial paleoclimate and paleoenvironment in a region near sea-level. Our field observations and thin section characterizations of the Oligocene and Miocene continental carbonates in south Texas identified three types of pedogenic carbonates, including rhizoliths, carbonate nodules, and platy horizons, and two types of groundwater carbonates, including carbonate-cemented beds and carbonate concretions, with distinctive macromorphologic and micromorphologic features. Based on preservations of authigenic microfabrics and variations of carbon and oxygen isotopic compositions, we suggest these carbonates experienced minimal diagenesis, and their stable isotopic compositions reflect paleoclimate and paleoenvironment in south Texas. Our Oligocene and Miocene carbonate clumped isotope temperatures (T(Δ47)) are 23-28 °C, slightly less than or comparable to the range of modern mean annual and mean warm season air temperature (21-27 °C) in the study area. These T(Δ47) values do not show any dependency on carbonate-type, or trends through time suggesting that groundwater carbonates were formed at shallow depths. These data could indicate that air temperature in south Texas was relatively stable since the early Oligocene. The reconstructed paleo-surface water δ18O values are similar to modern surface water which could indicate that meteoric water δ18O values also remained stable since the early Oligocene. Mean pedogenic carbonate δ13C values increased - 4.6‰ during the late Miocene, most likely reflecting an expansion of C4 grassland in south Texas. This study provides the first mid- and late Cenozoic continental records of paleoclimate and paleoecology in a low-latitude, near sea-level region.

Uranium distribution in Baikal sediments using SSNTD method for paleoclimate reconstruction

CERN Document Server

Zhmodik, S M; Nemirovskaya, N A; Zhatnuev, N S

1999-01-01

First data on local distribution of uranium in the core of Lake Baikal floor sediments (Academician ridge, VER-95-2, St 3 BC, 53 deg. 113'12'N/108 deg. 25'01'E) are presented in this paper. They have been obtained using (n,f)-radiography. Various forms of U-occurrence in floor sediments are shown, i.e. evenly disseminated, associated with clayey and diatomaceous components; micro- and macroinclusions of uranium bearing minerals - microlocations with uranium content 10-50 times higher than U-concentrations associated with clayey and diatomaceous components. Relative and absolute U-concentration can be determined for every mineral. Signs of various order periodicity of U-distribution in the core of Lake Baikal floor sediments have been found. Using (n,f)-radiography method of the study of Baikal floor sediment permits gathering of new information that can be used at paleoclimate reconstruction.

Nd isotope constraints on ocean circulation, paleoclimate, and continental drainage during the Jurassic breakup of Pangea

DEFF Research Database (Denmark)

Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.

2015-01-01

, western Russia, and North America. Combined with an extensive compilation of published εNd(t) data, our results show that the continental sources of Nd were very heterogeneous across the world. Volcanic inputs from a Jurassic equivalent of the modern Pacific Ring of Fire contributed to radiogenic ε......-Tethyan, and western Russian waters varied quite similarly through time, in response to regional changes in oceanic circulation, paleoclimate, continental drainage, and volcanism. Three positive shifts in εNd(t) values occurred successively in these epicontinental seas during the Pliensbachian, in the Aalenian...

Dante’s Inferno and the McGill Pain Questionnaire

Directory of Open Access Journals (Sweden)

R. Marcolongo

2011-09-01

Full Text Available Aims of the study: To study the images which depict the damned’s sufferings in Dante’s Inferno, in their expression of the several meanings of “pain”, the semantics of “pain” in the poem has been analyzed, eventually trying to determine whether the organization of punishments of Inferno may somehow mirror a disability scale. Methods: A detailed analysis of the text was carried out, which proved a valuable tool for interpreting the organization of punishments as a possible disability scale. The semantics of pain in the Divine Comedy was studied through all the forms of the pain descriptors (included the archaic terminological forms from the Italian version of the McGill Pain Questionnaire (MGPQ by Maiani and Sanavio. Results and Conclusions: In Dante’s Inferno a classification of pain is provided, based on the experience of sufferings; Dante’s images seem not only instrumental to investigating the sensorial but also the affective and intellectual spheres by introducing a number of characters and describing the impact of punishment onto their souls. Our research highlighted that 46 out of 78 terms from the MGPQ are present in Inferno, though with different forms; the Groups the MGPQ is divided into are also represented with the exception of Group XII, the most frequently detected being Groups XIII-which studies the fear-related sensations in the emotional sphere - XIV, XIX and XX. The great attention emerges that Dante devoted to describing simple sensorial experiences as well as the way punishments affected the soul. As a whole, the terms pertaining to the sensorial sphere are the most frequently encountered. The lack of motion which increases circle after circle in Hell, well matches the progressing physical and psychological impairment caused by some invalidating diseases. Noticeably, Dante created such a complex system centuries before the studies were released on the impact of pain and its quantitative and mostly qualitative

The McGill simulator for endoscopic sinus surgery (MSESS): a validation study.

Science.gov (United States)

Varshney, Rickul; Frenkiel, Saul; Nguyen, Lily H P; Young, Meredith; Del Maestro, Rolando; Zeitouni, Anthony; Saad, Elias; Funnell, W Robert J; Tewfik, Marc A

2014-10-24

Endoscopic sinus surgery (ESS) is a technically challenging procedure, associated with a significant risk of complications. Virtual reality simulation has demonstrated benefit in many disciplines as an important educational tool for surgical training. Within the field of rhinology, there is a lack of ESS simulators with appropriate validity evidence supporting their integration into residency education. The objectives of this study are to evaluate the acceptability, perceived realism and benefit of the McGill Simulator for Endoscopic Sinus Surgery (MSESS) among medical students, otolaryngology residents and faculty, and to present evidence supporting its ability to differentiate users based on their level of training through the performance metrics. 10 medical students, 10 junior residents, 10 senior residents and 3 expert sinus surgeons performed anterior ethmoidectomies, posterior ethmoidectomies and wide sphenoidotomies on the MSESS. Performance metrics related to quality (e.g. percentage of tissue removed), efficiency (e.g. time, path length, bimanual dexterity, etc.) and safety (e.g. contact with no-go zones, maximum applied force, etc.) were calculated. All users completed a post-simulation questionnaire related to realism, usefulness and perceived benefits of training on the MSESS. The MSESS was found to be realistic and useful for training surgical skills with scores of 7.97 ± 0.29 and 8.57 ± 0.69, respectively on a 10-point rating scale. Most students and residents (29/30) believed that it should be incorporated into their curriculum. There were significant differences between novice surgeons (10 medical students and 10 junior residents) and senior surgeons (10 senior residents and 3 sinus surgeons) in performance metrics related to quality (p education. This simulator may be a potential resource to help fill the void in endoscopic sinus surgery training.

Content validation of a Danish version of "The McGill Ingestive Skills Assessment" for dysphagia management.

Science.gov (United States)

Hansen, Tina; Lambert, Heather C; Faber, Jens

2011-12-01

This study addresses the first steps in the cross-cultural adaptation of a Danish version of the McGill Ingestive Skills Assessment (MISA), which quantifies eating and drinking abilities by scoring a meal observation. The original Canadian MISA was translated and adapted into Danish (MISA-DK). For content validation of the MISA-DK, a judgemental quantification process was applied using 13 experts. Thereafter, the MISA-DK was pilot tested by 16 occupational therapists. Finally, the MISA-DK was linked to the International Classification of Functioning, Disability and Health (ICF). Content validity of 43 items was found for 93% in terms of adequacy, 67% in terms of clarity of item description, 86% in terms of clarity of score descriptions, and 93% in terms of relevance. Thirteen of 14 sections of the instruction manual and score sheet were content valid. In light of these results, a revised MISA-DK was produced for the pilot test, which then found content validity for all sections and 98% of the items. The ICF linking resulted in 41 ICF-categories, which may reflect the complexity of eating and drinking as well as a multidimensional structure of the MISA-DK. In conclusion, the MISA-DK is prepared for psychometric testing using classical as well as modern test theory.

Climate regime shifts in paleoclimate time series from the Yucatán Peninsula: from the Preclassic to Classic period

Science.gov (United States)

Polanco Martínez, Josue M.; Medina-Elizalde, Martin; Burns, Stephen J.; Jiang, Xiuyang; Shen, Chuan-Chou

2015-04-01

It has been widely accepted by the paleoclimate and archaeology communities that extreme climate events (especially droughts) and past climate change played an important role in the cultural changes that occurred in at least some parts of the Maya Lowlands, from the Pre-Classic (2000 BC to 250 AD) to Post-Classic periods (1000 to 1521 AD) [1, 2]. In particular, a large number of studies suggest that the decline of the Maya civilization in the Terminal Classic Period was greatly influenced by prolonged severe drought events that probably triggered significant societal disruptions [1, 3, 4, 5]. Going further on these issues, the aim of this work is to detect climate regime shifts in several paleoclimate time series from the Yucatán Peninsula (México) that have been used as rainfall proxies [3, 5, 6, 7]. In order to extract information from the paleoclimate data studied, we have used a change point method [8] as implemented in the R package strucchange, as well as the RAMFIT method [9]. The preliminary results show for all the records analysed a prominent regime shift between 400 to 200 BCE (from a noticeable increase to a remarkable fall in precipitation), which is strongest in the recently obtained stalagmite (Itzamna) delta18-O precipitation record [7]. References [1] Gunn, J. D., Matheny, R. T., Folan, W. J., 2002. Climate-change studies in the Maya area. Ancient Mesoamerica, 13(01), 79-84. [2] Yaeger, J., Hodell, D. A., 2008. The collapse of Maya civilization: assessing the interaction of culture, climate, and environment. El Niño, Catastrophism, and Culture Change in Ancient America, 197-251. [3] Hodell, D. A., Curtis, J. H., Brenner, M., 1995. Possible role of climate in the collapse of Classic Maya civilization. Nature, 375(6530), 391-394. [4] Aimers, J., Hodell, D., 2011. Societal collapse: Drought and the Maya. Nature 479(7371), 44-45 (2011). [5] Medina-Elizalde, M., Rohling, E. J., 2012. Collapse of Classic Maya civilization related to modest reduction

Sources and Impacts of Modeled and Observed Low-Frequency Climate Variability

Science.gov (United States)

Parsons, Luke Alexander

Here we analyze climate variability using instrumental, paleoclimate (proxy), and the latest climate model data to understand more about the sources and impacts of low-frequency climate variability. Understanding the drivers of climate variability at interannual to century timescales is important for studies of climate change, including analyses of detection and attribution of climate change impacts. Additionally, correctly modeling the sources and impacts of variability is key to the simulation of abrupt change (Alley et al., 2003) and extended drought (Seager et al., 2005; Pelletier and Turcotte, 1997; Ault et al., 2014). In Appendix A, we employ an Earth system model (GFDL-ESM2M) simulation to study the impacts of a weakening of the Atlantic meridional overturning circulation (AMOC) on the climate of the American Tropics. The AMOC drives some degree of local and global internal low-frequency climate variability (Manabe and Stouffer, 1995; Thornalley et al., 2009) and helps control the position of the tropical rainfall belt (Zhang and Delworth, 2005). We find that a major weakening of the AMOC can cause large-scale temperature, precipitation, and carbon storage changes in Central and South America. Our results suggest that possible future changes in AMOC strength alone will not be sufficient to drive a large-scale dieback of the Amazonian forest, but this key natural ecosystem is sensitive to dry-season length and timing of rainfall (Parsons et al., 2014). In Appendix B, we compare a paleoclimate record of precipitation variability in the Peruvian Amazon to climate model precipitation variability. The paleoclimate (Lake Limon) record indicates that precipitation variability in western Amazonia is 'red' (i.e., increasing variability with timescale). By contrast, most state-of-the-art climate models indicate precipitation variability in this region is nearly 'white' (i.e., equally variability across timescales). This paleo-model disagreement in the overall

Multi-proxy Paleoclimate and CO2 Reconstruction from the Latest Middle Eocene Sedimentary Fill of a Subarctic Kimberlitic Maar Crater

Science.gov (United States)

Reyes, A. V.; Wolfe, A. P.; Royer, D. L.; Greenwood, D. R.; Tierney, J. E.; Doria, G.; Gagen, M. H.; Siver, P.; Westgate, J.

2016-12-01

Eocene paleoclimate reconstructions are rarely accompanied by parallel estimates of CO2, complicating assessment of the equilibrium climate responses to CO2. We reconstruct temperature, precipitation, and CO2 from latest middle Eocene ( 38 Myrs ago) peats in subarctic Canada, preserved in sediments that record infilling of a kimberlite pipe maar crater. Mutual climatic range analyses of pollen, together with oxygen isotope analyses of a-cellulose from unpermineralized wood and inferenecs from branched glycerol diakyl glycerol tetraethers (GDGTs), reveal a high-latitude humid-temperate forest ecosystem with mean annual temperatures (MATs) >17 °C warmer than present, mean coldest month temperatures above 0 °C, and mean annual precipitation 4x present. Metasequoia stomatal indices and gas-exchange modeling produce median CO2 concentrations of 634 and 432 ppm, respectively, with a consensus median estimate of 494 ppm. Reconstructed MATs are >6 °C warmer than those produced by Eocene climate models forced at 560 ppm CO2, underscoring the capacity for exceptional polar amplification of warming and hydrological intensification under relatively modest CO2 concentrations, once both fast and slow feedbacks become expressed.

Paleoclimate Reconstruction of Guangxi in SW China during the Past 2000-Year: Stalagmite Records from Two Caves

Science.gov (United States)

Lien, W. Y.; Li, H. C.; Mii, H. S.

2017-12-01

Paleoclimate reconstructions help us to understand the role of the East Asian Summer Monsoon (EASM) on local precipitation and controlling factor of EASM variability, and to improve our climatic prediction. This study presents two stalagmite records from Jinlun Cave (23.553oN, 108.265oE) and Yilingyan Cave (23.041oN, 108.297oE) which are only 60 km apart in Guangxi Province, China. The 35-cm long stalagmite JL12 from Jinlun Cave and 10-cm long stalagmite YLY12 from Yilingyan Cave reveal 1500-year and 2000-year continuous growth respectively based on AMS 14C dating. Data points of the AMS 14C dates with the least dead carbon fraction (DCF) are used to build up the age model. Although dead carbons influence the 14C dating results, it is a feasible dating method for the stalagmites as 230Th/U dating on both stalagmites was not successful due to low U contents. A total of 1586 samples from JL12 and 948 samples from YLY12 have been done for stable isotopes analyses to serve as paleoclimate proxies. Comparison of the d18O records with the local rainfall records and the dry-wetness historic records shows the stalagmite d18O records as a rainfall proxy. The JL12 d18O record resembles the YLY12 d18O record in general, though some differences exist, which confirms the d18O records representing the local climate. The relatively lighter (lower) d18O values of the JL12 and YLY12 records during the Medieval Warm Period (MWP, AD900-1200) indicate stronger EASM. In the first phase of Little Ice Age (LIA), from AD1300 to AD1560, the d18O fluctuate drastically and the average during this period was lower, while the d18O was higher in the second phase of Little Ice Age (AD1560-AD1760), exhibiting a drier and stable climate in the second phase. Furthermore, the DCF varies through the stalagmite records, ascending during the LIA, descending during the MWP, which informs dry condition during the LIA and a moist climate in the MWP. Spectral analysis of the high-resolution d18O records

The sensitivity of the Arctic sea ice to orbitally induced insolation changes: a study of the mid-Holocene Paleoclimate Modelling Intercomparison Project 2 and 3 simulations

Directory of Open Access Journals (Sweden)

M. Berger

2013-04-01

Full Text Available In the present work the Arctic sea ice in the mid-Holocene and the pre-industrial climates are analysed and compared on the basis of climate-model results from the Paleoclimate Modelling Intercomparison Project phase 2 (PMIP2 and phase 3 (PMIP3. The PMIP3 models generally simulate smaller and thinner sea-ice extents than the PMIP2 models both for the pre-industrial and the mid-Holocene climate. Further, the PMIP2 and PMIP3 models all simulate a smaller and thinner Arctic summer sea-ice cover in the mid-Holocene than in the pre-industrial control climate. The PMIP3 models also simulate thinner winter sea ice than the PMIP2 models. The winter sea-ice extent response, i.e. the difference between the mid-Holocene and the pre-industrial climate, varies among both PMIP2 and PMIP3 models. Approximately one half of the models simulate a decrease in winter sea-ice extent and one half simulates an increase. The model-mean summer sea-ice extent is 11 % (21 % smaller in the mid-Holocene than in the pre-industrial climate simulations in the PMIP2 (PMIP3. In accordance with the simple model of Thorndike (1992, the sea-ice thickness response to the insolation change from the pre-industrial to the mid-Holocene is stronger in models with thicker ice in the pre-industrial climate simulation. Further, the analyses show that climate models for which the Arctic sea-ice responses to increasing atmospheric CO2 concentrations are similar may simulate rather different sea-ice responses to the change in solar forcing between the mid-Holocene and the pre-industrial. For two specific models, which are analysed in detail, this difference is found to be associated with differences in the simulated cloud fractions in the summer Arctic; in the model with a larger cloud fraction the effect of insolation change is muted. A sub-set of the mid-Holocene simulations in the PMIP ensemble exhibit open water off the north-eastern coast of Greenland in summer, which can provide a fetch

Recent eolian activity and paleoclimate fluctuations in the Ferris Lost Soldier Area, South-Central Wyoming

Science.gov (United States)

Gaylord, D. R.

1983-09-01

The Ferris Dune Fields were examined. Sand dunes are especially valuable in paleoclimate reconstructions because they: (1) bury and preserve datable materials and artifacts; (2) respond to even subtle changes in wind velocity and direction as reflected both in external morphology and internal structures; and (3) remain unconsolidated, making them amenable to easy textural and compositional examination. The valley of Clear Creek in the Ferris Dunes reveals a relatively continuous Holocene section of interbedded dune and interdunal pond deposits. Radiocarbon dates from the interdunal pond strata at Clear Creek, theoretical sand dune migration rates, compositional analysis of periglacial sand wedges, and relative dating of actively migrating parabolic dunes reveals a general sequence of geologic-climatic events that affected the Ferris-Lost Soldier area. The most recent major reactivaton of dunes occurred approximately 290 years ago.

Examining the provenance of branched GDGTs in the Tagus River drainage basin and its outflow into the Atlantic Ocean over the Holocene to determine their usefulness for paleoclimate applications

NARCIS (Netherlands)

Warden, L.; Kim, J.-H; Zell, C.; Vis, G.-J.; de Stigter, H.C.; Bonnin, J.; Sinninghe Damste, J.S.

2016-01-01

The distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from the soils where they are predominantly produced to marine sediments via rivers, have been applied in reconstructing mean annual air temperature (MAT) and pH of soils. However, paleoclimate

Pleistocene climate, phylogeny, and climate envelope models: an integrative approach to better understand species' response to climate change.

Directory of Open Access Journals (Sweden)

A Michelle Lawing

Full Text Available Mean annual temperature reported by the Intergovernmental Panel on Climate Change increases at least 1.1°C to 6.4°C over the next 90 years. In context, a change in climate of 6°C is approximately the difference between the mean annual temperature of the Last Glacial Maximum (LGM and our current warm interglacial. Species have been responding to changing climate throughout Earth's history and their previous biological responses can inform our expectations for future climate change. Here we synthesize geological evidence in the form of stable oxygen isotopes, general circulation paleoclimate models, species' evolutionary relatedness, and species' geographic distributions. We use the stable oxygen isotope record to develop a series of temporally high-resolution paleoclimate reconstructions spanning the Middle Pleistocene to Recent, which we use to map ancestral climatic envelope reconstructions for North American rattlesnakes. A simple linear interpolation between current climate and a general circulation paleoclimate model of the LGM using stable oxygen isotope ratios provides good estimates of paleoclimate at other time periods. We use geologically informed rates of change derived from these reconstructions to predict magnitudes and rates of change in species' suitable habitat over the next century. Our approach to modeling the past suitable habitat of species is general and can be adopted by others. We use multiple lines of evidence of past climate (isotopes and climate models, phylogenetic topology (to correct the models for long-term changes in the suitable habitat of a species, and the fossil record, however sparse, to cross check the models. Our models indicate the annual rate of displacement in a clade of rattlesnakes over the next century will be 2 to 3 orders of magnitude greater (430-2,420 m/yr than it has been on average for the past 320 ky (2.3 m/yr.

A model-data comparison of the Holocene global sea surface temperature evolution

NARCIS (Netherlands)

Lohmann, G.; Pfeiffer, M.; Laepple, T.; Leduc, G.; Kim, J.-H.

2013-01-01

We compare the ocean temperature evolution of the Holocene as simulated by climate models and reconstructed from marine temperature proxies. We use transient simulations from a coupled atmosphere-ocean general circulation model, as well as an ensemble of time slice simulations from the Paleoclimate

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

Directory of Open Access Journals (Sweden)

W. Jackson Davis

2018-01-01

Full Text Available We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (±2.4% in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP, and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs known to precede Dansgaard-Oeschger (D-O oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years declined by half while amplitude (mean 0.67 °C approximately doubled. The period and amplitude of ACOs oscillate in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature

Teaching the fundamentals of the modelling of cyber-physical systems

OpenAIRE

Tendeloo, Van, Yentl; Vangheluwe, Hans

2016-01-01

Abstract: Current Cyber-Physical Systems are becoming too complex to model and simulate using the usual approaches. This complexity is not only due to a large number of components, but also by the increasing diversity of components and problem aspects. In this paper, we report on over a decade of experience in teaching the modelling and simulation of complex Cyber-Physical Systems, at both McGill University, and the University of Antwerp. We tackle complexity through the use of multiple forma...

Paleoclimate Signals and Temperature Reconstructions for the Northeastern United States using Atlantic White Cedar Tree-Rings

Science.gov (United States)

Pearl, J. K.; Anchukaitis, K. J.; Pederson, N.; Donnelly, J. P.

2016-12-01

High-resolution paleoclimate records of the Common Era are essential for improving detection and attribution of internal and forced climate system responses. The densely populated northeastern United States is at risk from impending climate shifts as well as sea level rise. Here we present a new network of annually resolved proxy data from Atlantic white cedar trees throughout the northeastern United States. Ring width variability reflects winter through summer temperatures at inland sites north of New Jersey. Climate signals embedded in the full network are evaluated for their potential to provide reconstructions of both temperature and drought variability. We demonstrate skillful climate reconstructions for the last several centuries and the potential to use subfossil samples to extend these records over the Common Era. Our tree-ring network provides the long-term context at multidecadal and centennial time scales for the large-scale ocean-atmospheric processes that influence the climate of the region.

Impacts of Mega-droughts on Water and Food Security in the Indo-Gangetic Plains: A Paleoclimate Scenario Analysis

Science.gov (United States)

Zhu, T.; Pitois, G.; Ringler, C.; Wang, D.; Rosegrant, M. W.

2014-12-01

Spanning over Pakistan, northern India, Nepal, and Bangladesh, the Indo-Gangetic Plains (IGP) is the home of several hundred million people and the "bread basket" for much of South Asia. The flat terrain, fertile soils, and favorable climate of the IGP make it agriculturally productive. However prolonged droughts caused by consecutive monsoon failures can seriously affect crop production and social wellbeing, in particular for the eastern part of the plains where agriculture remains largely rain-fed. Severe droughts were observed in the IGP historically, and recent paleoclimate studies reveal that more severe and long-lasting "mega-droughts" had happened in the distant past. Agricultural losses from major droughts can dramatically affect food systems and increase the vulnerability of resource-poor people given the delicate balance between food supply and demand under growing natural resource scarcity. To estimate the potential impacts of "mega-droughts" on the water and food systems in the IGP, we develop worst-case drought scenarios through inverse modeling of tree-ring-based PDSI reconstruction that covers the period 1300-1899 (A.D.), and analyze these historic mega-drought scenarios using IFPRI's IMPACT global water and food projections model. The base year of the IMPACT model is parameterized using socioeconomic and engineering data that reflect today's water management and infrastructure, agricultural technologies, population, income, and market institutions. The base year simulation is validated against observations to ensure model fidelity. Anticipated changes of the above factors in the future out to 2050 are specified using demographic and economic growth projections and literature data. Model simulation results represent the consequences of mega-droughts in the IGP given technological and socioeconomic conditions of today and in the future. We also explore policy options for increasing the resilience of water and food systems in the IGP, through scenario

Climate modeling - a tool for the assessment of the paleodistribution of source and reservoir rocks

Energy Technology Data Exchange (ETDEWEB)

Roscher, M.; Schneider, J.W. [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Geologie; Berner, U. [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany). Referat Organische Geochemie/Kohlenwasserstoff-Forschung

2008-10-23

In an on-going project of BGR and TU Bergakademie Freiberg, numeric paleo-climate modeling is used as a tool for the assessment of the paleo-distribution of organic rich deposits as well as of reservoir rocks. This modeling approach is based on new ideas concerning the formation of the Pangea supercontinent. The new plate tectonic concept is supported by paleo- magnetic data as it fits the 95% confidence interval of published data. Six Permocarboniferous time slices (340, 320, 300, 290, 270, 255 Ma) were chosen within a first paleo-climate modeling approach as they represent the most important changes of the Late Paleozoic climate development. The digital maps have a resolution of 2.8 x 2.8 (T42), suitable for high-resolution climate modeling, using the PLASIM model. CO{sub 2} concentrations of the paleo-atmosphere and paleo-insolation values have been estimated by published methods. For the purpose of validation, quantitative model output, had to be transformed into qualitative parameters in order to be able to compare digital data with qualitative data of geologic indicators. The model output of surface temperatures and precipitation was therefore converted into climate zones. The reconstructed occurrences of geological indicators like aeolian sands, evaporites, reefs, coals, oil source rocks, tillites, phosphorites and cherts were then compared to the computed paleo-climate zones. Examples of the Permian Pangea show a very good agreement between model results and geological indicators. From the modeling approach we are able to identify climatic processes which lead to the deposition of hydrocarbon source and reservoir rocks. The regional assessment of such atmospheric processes may be used for the identification of the paleo-distribution of organic rich deposits or rock types suitable to form hydrocarbon reservoirs. (orig.)

LGM permafrost distribution: how well can the latest PMIP multi-model ensembles reconstruct?

OpenAIRE

K. Saito; T. Sueyoshi; S. Marchenko; V. Romanovsky; B. Otto-Bliesner; J. Walsh; N. Bigelow; A. Hendricks; K. Yoshikawa

2013-01-01

Global-scale frozen ground distribution during the Last Glacial Maximum (LGM) was reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present-day (pre-industrial; 0 k) and the LGM (...

A Record of Holocene Paleoclimate Evolution from Robertson Bay, Victoria Land, Antarctica

Science.gov (United States)

Riesselman, C. R.; Truax, O.; Wilson, G. S.; Parker, R. L.; Yoo, K. C.; Lee, J. I.; Levy, R. H.; Mckay, R. M.

2017-12-01

Regionally representative records of how Antarctica responded to the transition from the Last Glacial Maximum into the Holocene are an essential component of understanding the processes by which the Antarctic cryosphere responds to a changing climate. Here, we present a high-resolution record of Holocene Antarctic paleoclimate evolution from a previously unstudied section of the Victoria Land margin. In 2015 the Korea Polar Research Institute collected a 571 cm sediment core, GC57, from Robertson Bay, a protected embayment west of Cape Adare and adjacent to the outlet glaciers of the Transantarctic Mountains. Using diatom assemblages, bulk sediment geochemistry, and the magnetic properties of GC57, we aim to reconstruct the response of the East Antarctic Ice Sheet to warming associated with deglaciation and the Holocene climatic optima at the interface between the Ross Sea and the Southern Ocean. Our multiproxy approach allows us to study sea ice extent, seasonality, ocean stratification and circulation, and primary productivity from the mid-Holocene (7,400 14C year BP) to the present. A sea-ice associated diatom assemblage indicative of summer sea surface temperatures below 0˚C dominates the basal section of GC57. Although diatoms are well preserved, the unit is characterized by low wt% biogenic silica (average 9%) and a high concentration of magnetic minerals, indicating that biogenic production persisted despite substantial terrigenous input into the bay. A rapid transition at 4708 14C yr BP is identified by a steep increase in wt% BSi (average 13%), a decrease in magnetic minerals, and a subtle assemblage change towards sea-ice associated diatoms with slightly warmer temperature tolerances. The novel ramped pyrolosis 14C dating methodology allows us to date the carbon fixed concurrent with deposition and generate a robust age model for GC57 with an accuracy previously difficult to achieve given the uncertainties associated with dating bulk acid insoluble

LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction?

OpenAIRE

Saito, K.; Sueyoshi, T.; Marchenko, S.; Romanovsky, V.; Otto-Bliesner, B.; Walsh, J.; Bigelow, N.; Hendricks, A.; Yoshikawa, K.

2013-01-01

Here, global-scale frozen ground distribution from the Last Glacial Maximum (LGM) has been reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project phase III (PMIP3) simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present day (pre-industrial; 0 kya) an...

Detecting and Quantifying Paleoseasonality in Stalagmites using Geochemical and Modelling Approaches

Science.gov (United States)

Baldini, J. U. L.

2017-12-01

Stalagmites are now well established sources of terrestrial paleoclimate information, providing insights into climate change on a variety of timescales. One of the most exciting aspects of stalagmites as climate archives is their ability to provide information regarding seasonality, a notoriously difficult component of climate change to characterise. However, stalagmite geochemistry may reflect not only the most apparent seasonal signal in external climate parameters, but also cave-specific signals such as seasonal changes in cave air carbon dioxide concentrations, sudden shifts in ventilation, and stochastic hydrological processes. Additionally, analytical bias may dampen or completely obfuscate any paleoseasonality, highlighting the need for appropriate quantification of this issue using simple models. Evidence from stalagmites now suggests that a seasonal signal is extractable from many samples, and that this signal can provide an important extra dimension to paleoclimate interpretations. Additionally, lower resolution annual- to decadal-scale isotope ratio records may also reflect shifts in seasonality, but identifying these is often challenging. Integrating geochemical datasets with models and cave monitoring data can greatly increase the accuracy of climate reconstructions, and yield the most robust records.

Leçons d’analyse classique exposition d'un cours fait par Paul Koosis à l'Université McGill, Montréal

CERN Document Server

Poulin, Philippe

2015-01-01

Ce livre est basé sur un cours de deuxième cycle donné en 2005-2006 par M. Paul Koosis, professeur émérite à l'université McGill. Il traite de sujets soigneusement choisis par le professeur à l'intention de ceux qui, plutôt que de rechercher un catalogue exhaustif de résultats techniques et abstraits, veulent être initiés aux découvertes les plus essentielles et prolifiques de l'analyse classique du vingtième siècle. Analyse harmonique, quasi-analyticité, zéros des fonctions entières (dont une preuve inédite du théorème de Levinson-Cartwright), approximation pondérée, principe d'incertitude, mesures harmoniques…, les résultats saillants et géniaux de l'analyse classique sont présentés dans un style soigné, rigoureux et détaillé, préparant les étudiants à des études plus poussées ; et au service du lecteur qui, connaissant les bases de la théorie de la mesure et de l'analyse complexe, désire suivre le merveilleux développement de M. Koosis et accroître sa connaissance d...

Constraining Lipid Biomarker Paleoclimate Proxies in a Small Arctic Watershed

Science.gov (United States)

Dion-Kirschner, H.; McFarlin, J. M.; Axford, Y.; Osburn, M. R.

2017-12-01

Arctic amplification of climate change renders high-latitude environments unusually sensitive to changes in climatic conditions (Serreze and Barry, 2011). Lipid biomarkers, and their hydrogen and carbon isotopic compositions, can yield valuable paleoclimatic and paleoecological information. However, many variables affect the production and preservation of lipids and their constituent isotopes, including precipitation, plant growth conditions, biosynthesis mechanisms, and sediment depositional processes (Sachse et al., 2012). These variables are particularly poorly constrained for high-latitude environments, where trees are sparse or not present, and plants grow under continuous summer light and cool temperatures during a short growing season. Here we present a source-to-sink study of a single watershed from the Kangerlussuaq region of southwest Greenland. Our analytes from in and around `Little Sugarloaf Lake' (LSL) include terrestrial and aquatic plants, plankton, modern lake water, surface sediments, and a sediment core. This diverse sample set allows us to fulfill three goals: 1) We evaluate the production of lipids and isotopic signatures in the modern watershed in comparison to modern climate. Our data exhibit genus-level trends in leaf wax production and isotopic composition, and help clarify the difference between terrestrial and aquatic signals. 2) We evaluate the surface sediment of LSL to determine how lipid biomarkers from the watershed are incorporated into sediments. We constrain the relative contributions of terrestrial plants, aquatic plants, and other aquatic organisms to the sediment in this watershed. 3) We apply this modern source-to-sink calibration to the analysis of a 65 cm sediment core record. Our core is organic-rich, and relatively high deposition rates allow us to reconstruct paleoenvironmental changes with high resolution. Our work will help determine the veracity of these common paleoclimate proxies, specifically for research in

Tectonics, orbital forcing, global climate change, and human evolution in Africa: introduction to the African paleoclimate special volume.

Science.gov (United States)

Maslin, Mark A; Christensen, Beth

2007-11-01

The late Cenozoic climate of Africa is a critical component for understanding human evolution. African climate is controlled by major tectonic changes, global climate transitions, and local variations in orbital forcing. We introduce the special African Paleoclimate Issue of the Journal of Human Evolution by providing a background for and synthesis of the latest work relating to the environmental context for human evolution. Records presented in this special issue suggest that the regional tectonics, appearance of C(4) plants in East Africa, and late Cenozoic global cooling combined to produce a long-term drying trend in East Africa. Of particular importance is the uplift associated with the East African Rift Valley formation, which altered wind flow patterns from a more zonal to more meridinal direction. Results in this volume suggest a marked difference in the climate history of southern and eastern Africa, though both are clearly influenced by the major global climate thresholds crossed in the last 3 million years. Papers in this volume present lake, speleothem, and marine paleoclimate records showing that the East African long-term drying trend is punctuated by episodes of short, alternating periods of extreme wetness and aridity. These periods of extreme climate variability are characterized by the precession-forced appearance and disappearance of large, deep lakes in the East African Rift Valley and paralleled by low and high wind-driven dust loads reaching the adjacent ocean basins. Dating of these records show that over the last 3 million years such periods only occur at the times of major global climatic transitions, such as the intensification of Northern Hemisphere Glaciation (2.7-2.5 Ma), intensification of the Walker Circulation (1.9-1.7 Ma), and the Mid-Pleistocene Revolution (1-0.7 Ma). Authors in this volume suggest this onset occurs as high latitude forcing in both Hemispheres compresses the Intertropical Convergence Zone so that East Africa

Late Cretaceous paleosols as paleoclimate proxies of high-latitude Southern Hemisphere: Mata Amarilla Formation, Patagonia, Argentina

Science.gov (United States)

Varela, Augusto N.; Raigemborn, M. Sol; Richiano, Sebastián; White, Tim; Poiré, Daniel G.; Lizzoli, Sabrina

2018-01-01

Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental paleoclimate reconstructions are scarce and exclusively derived from paleontological records. Using paleosol-derived climofunction studies of the mid- to Upper Cretaceous Mata Amarilla Formation, southern Patagonia, Argentina, we present a reconstruction of the mid-Cretaceous climate of southern South America. Our results indicate that at 60° south paleolatitude during the Cenomanian-Santonian stages, the climate was subtropical temperate-warm (12 °C ± 2.1 °C) and humid (1404 ± 108 mm/yr) with marked rainfall seasonality. These results are consistent with both previous estimations from the fossil floras of the Mata Amarilla Formation and other units of the Southern Hemisphere, and with the previous observations of the displacement of tropical and subtropical floras towards the poles in both hemispheres. The data presented here show a more marked seasonality and slightly lower mean annual precipitation and mean annual temperature values than those recorded at the same paleolatitudes in the Northern Hemisphere.

Fire, Ice and Water: Glaciologic, Paleoclimate and Anthropogenic Linkages During Past Mega-Droughts in the Uinta Mountains, Utah

Science.gov (United States)

Power, M. J.; Rupper, S.; Codding, B.; Schaefer, J.; Hess, M.

2017-12-01

Alpine glaciers provide a valuable water source during prolonged drought events. We explore whether long-term climate dynamics and associated glacier changes within mountain drainage basins and adjacent landscapes ultimately influence how prehistoric human populations choose settlement locations. The Uinta Mountains of Utah, with a steep present-day precipitation gradient from the lowlands to the alpine zone of 20-100 cm per year, has a rich glacial history related to natural and anthropogenic climate variability. Here we examine how past climate variability has impacted glaciers and ultimately the availability of water over long timescales, and how these changes affected human settlement and subsistence decisions. Through a combination of geomorphologic evidence, paleoclimate proxies, and glacier and climate modelling, we test the hypothesis that glacier-charged hydrologic systems buffer prehistoric populations during extreme drought periods, facilitating long-term landscape management with fire. Initial field surveys suggest middle- and low-elevation glacial valleys contain glacially-derived sediment from meltwater and resulted in terraced river channels and outwash plains visible today. These terraces provide estimates of river discharge during varying stages of glacier advance and retreat. Archaeological evidence from middle- and high-elevations in the Uinta Mountains suggests human populations persisted through periods of dramatic climate change, possibly linked to the persistence of glacially-derived water resources through drought periods. Paleoenvironmental records indicate a long history of fire driven by the combined interaction of climatic variation and human disturbance. This research highlights the important role of moisture variability determining human settlement patterns and landscape management throughout time, and has direct relevance to the impacts of anthropogenic precipitation and glacier changes on vulnerable populations in the coming century

Paleoclimate Signals and Age Distributions from 41 Public Water Works in the Netherlands

Science.gov (United States)

Broers, H. P.; Weert, J. D.; Sültenfuß, J.; Aeschbach, W.; Vonhof, H.; Casteleijns, J.

2015-12-01

Knowing the age distribution of water abstracted from public water supply wells is of prime importance to ensure customer trust and to underpin predictions of water quality evolution in time. Especially, age distributions enable the assessment of the vulnerability of well fields, both in relation to surface sources of contamination as in relation to subsurface sources, such as possibly related to shale gas extraction. We sampled the raw water of 41 large public supply well fields which represents a mixture of groundwaters and used the a discrete travel time distribution model (DTTDM, Visser et al. 2013, WRR) in order to quantify the age distribution of the mixture. Measurements included major ion chemistry, 3H, 3He, 4He, 18O, 2H, 14C, 13CDIC and 13CCH4 and the full range of noble gases. The heavier noble gases enable the calculation of the Noble Gas Temperature (NGT) which characterizes the temperature of past recharge conditions. The 14C apparent age of each mixture was derived correcting for dead carbon sources. The DTTDM used the 3H and 4He concentrations, the 14C apparent age and the NGT as the four distinctive tracers to estimate the age distributions. Especially 4He and NGT provide extra information on the older part of the age distributions and showed that the 14C apparent ages are often the result of mixing of waters ranging between 2.000 and 35.000 years old, instead of being discrete ages with a limited .variance as sometimes assumed.The results show a large range of age distributions, comprising vulnerable well fields with >60% young water (85% very old groundwater (> 25 kyrs) and all forms of TTD's in between. The age distributions are well in correspondence with the hydrogeological setting of the well fields; all well fields with an age distribution skewed towards older ages are in the Roer Valley Graben structure, where fluvial and marine aquitards provide protection from recent recharge. Especially waters from this graben structure exhibit clear

Temperature Covariance in Tree Ring Reconstructions and Model Simulations Over the Past Millennium

Czech Academy of Sciences Publication Activity Database

Hartl-Meier, C. T. M.; Büntgen, Ulf; Smerdon, J. E.; Zorita, E.; Krusic, P. J.; Ljungqvist, F. C.; Schneider, L.; Esper, J.

2017-01-01

Roč. 44, č. 18 (2017), s. 9458-9469 ISSN 0094-8276 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:68378076 Keywords : last millennium * northern-hemisphere * summer temperatures * american southwest * volcanic-eruptions * tibetan plateau * sierra-nevada * system model * central-asia * climate * paleoclimate * spatial temperature synchrony * millennial scale * radiative forcing * proxy model comparison Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 4.253, year: 2016

From Past to future: the Paleoclimate Modelling Intercomparison Project's contribution to CMIP6

Science.gov (United States)

Kageyama, Masa; Braconnot, Pascale; Harrison, Sandy; Haywood, Alan; Jungclaus, Johann; Otto-Bliesner, Bette; Abe-Ouchi, Ayako

2016-04-01

Since the 1990s, PMIP has developed with the following objectives: 1/to evaluate the ability of climate models used for climate prediction in simulating well-documented past climates outside the range of present and recent climate variability; 2/to understand the mechanisms of these climate changes, in particular the role of the different climate feedbacks. To achieve these goals, PMIP has actively fostered paleo-data syntheses, multi-model analyses, including analyses of relationships between model results from past and future simulations, and model-data comparisons. For CMIP6, PMIP will focus on five past periods: - the Last Millennium (850 CE - present), to analyse natural climate variability on multidecadal or longer time-scales - the mid-Holocene, 6000 years ago, to compare model runs with paleodata for a period of warmer climate in the Northern Hemisphere, with an enhanced hydrological cycle - the Last Glacial Maximum, 21000 years ago, to evaluate the ability of climate models to represent a cold climate extreme and examine whether paleoinformation about this period can help and constrain climate sensitivity - the Last InterGlacial (~127,000 year ago), which provides a benchmark for a period of high sea-level stand - the mid-Pliocene warm period (~3.2 million years ago), which allows for the evaluation of the model's long-term response to a CO2 level analogous to the modern one. This poster will present the rationale of these "PMIP4-CMIP6" experiments. Participants are invited to come and discuss about the experimental set-up and the model output to be distributed via CMIP6. For more information and discussion of the PMIP4-CMIP6 experimental design, please visit: https://wiki.lsce.ipsl.fr/pmip3/doku.php/pmip3:cmip6:design:index

Late Pliocene Depositional History and Paleoclimate Reconstructions of the Southwest Pacific

Science.gov (United States)

Royce, B.; Patterson, M. O.; Pietras, J.

2017-12-01

Drift deposits off the eastern margin of New Zealand are important archives for the paleoclimate and paleoceanographic history of the southwest Pacific. Ocean Drilling Program (ODP) Site 1123 is located on the North Chatham rise drift just North of the westerly wind driven Subtropical Front (STF) and provides a record of near continuous sediment deposition since the Miocene along the southwest Pacific deep western boundary current (DWBC). While the Miocene and Late Pleistocene portion of this record have been well studied, the Late Pliocene record is less well developed. Southern Ocean geological records demonstrate that Late Pliocene cooling is the transient time bracketing the warmer than present Early Pliocene and bipolar glaciation at 2.7 Ma. A newly developed, robust, and astronomically tuned long-term record of benthic δ13C from ODP Site 1123 spanning the Early to Late Pliocene implies a reduction in Southern Ocean ventilation and lowering of preformed values from waters sourced along the Antarctic margin during the Late Pliocene. Thus, Late Pliocene Southern Hemisphere cooling and sea ice expansion may have drastically reduced outgassing and increased the burial of heat into the deep ocean. South Atlantic records off the west coast of Africa demonstrate an increase in the flux of iron to the open ocean during this time potentially enhancing surface ocean productivity and providing an additional cooling mechanism. Currently, atmospheric transport of dust to the Southern Ocean is dominated by persistent mid-latitude circumpolar westerly winds; this is particularly relevant for dust sourced from New Zealand. The Late Pliocene to Early Pleistocene uplift of the North Island axial ranges and South Island southern alps potentially provided a greater amount of not only sediment to the deep ocean, but also wind blow dust to the Pacific sector of the Southern Ocean. We will present a detailed high-resolution sedimentological study on the development of the Chatham

Monthly paleostreamflow reconstruction from annual tree-ring chronologies

Science.gov (United States)

J. H. Stagge; D. E. Rosenberg; R. J. DeRose; T. M. Rittenour

2018-01-01

Paleoclimate reconstructions are increasingly used to characterize annual climate variability prior to the instrumental record, to improve estimates of climate extremes, and to provide a baseline for climate change projections. To date, paleoclimate records have seen limited engineering use to estimate hydrologic risks because water systems models and managers usually...

The use of Sphagnum cellulose oxygen isotope ratios in ombrotrophic peatlands as a proxy for paleoclimate.

Science.gov (United States)

Taylor, M.; Pendall, E.; Jackson, S.; Booth, R. K.; Nichols, J. E.; Huang, Y.

2006-12-01

Developing proxies for discerning paleoclimate that are independent of the pollen record can provide insight into various aspects of climate variability and improve confidence in the interpretation of climate-vegetation interactions. To date, proxies including plant macrofossils, humification indices, testate amoebae, and ratios of n-alkane abundances have been used to infer past climate variability from temperate ombrotrophic peatlands in upper Midwestern North America. These proxies are used to infer past changes in surface-moisture conditions, which in ombrotrophic peatlands is primarily a function of precipitation and temperature. This study investigates the potential uses of stable oxygen isotopes to complement hydrologic proxies. δ18O of surface water and Sphagnum moss cellulose from bogs throughout North America indicates a correlation between average growing season temperatures and δ18O-values. The existence of a modern temperature signal in moss cellulose suggests that δ18O-derived records will not only complement paleohydrological records, but also help assess relative changes in precipitation and temperature. Humification and testate amoebae data from two cores taken from Minden and Irwin Smith Bogs in central and northeastern Michigan have recorded several extreme drought events during the Holocene, including one at 1000 YBP. Comparison of δ18O-values of picked Sphagnum remains to down-core humification and testate amoebae data suggest good temporal correspondence, with the δ18O-values around 1000 YBP indicating a warmer growing season.

Rodent burrows in late Pleistocene paleosols at Korean Palaeolithic sites and their implications for paleoclimate changes

Science.gov (United States)

Lim, H.; Park, S.; Lee, J.; Lee, Y.

2013-12-01

Rodent burrows are commonly found at many Paleolithic archaeological sites in Korea. They are nearly straight in horizontal view and gently inclined in lateral view. Burrow diameters are mostly 7 - 10cm, and burrow length may reach a few meters. Vertical penetration depths are generally about 1 m from the surface, and the thickness of the burrow-bearing layer is about 1-2 m. Although no remains (bones, teeth, claws, and coprolites) were found within burrows, they are interpreted to have been produced by rodent-like mammals (probably ground squirrels) based on the size and architecture. According to the previous study, the age of these burrows was constrained to be between ca. 40,000 and 25,000 yr BP by tephrochronology, radiocarbon and optically stimulated luminescence dating results (Lim et al., 2007). However, little is known about the reason why these burrows have disappeared after late Pleistocene time. For this question, two explanations can be considered: extinction or migration. Since same kinds of burrows are still found in the high-latitude regions, such as Mongolia and North America, the possibility of extinction can be ruled out. Therefore, migration seems to be the most likely explanation. Our results show that the destruction of habitat caused by climate change during this period is the main reason for the northward migration of burrowing animals. This study suggests that rodent burrows found in the late Pleistocene paleosols can provide useful information on paleoclimate and paleoenvironmental changes.

Multiproxy Holocene paleoclimate records from the southern Peruvian Andes - what new can we learn from the stable carbon isotope composition of high altitude organic matter deposits?

Science.gov (United States)

Skrzypek, Grzegorz; Engel, Zbyněk

2015-04-01

Interpretation of the Central Andean paleoclimate over the last millennia still represents a research challenge demanding deeper studies [1,2]. Several high-resolution paleoclimate proxies for the last 10,000 years have been developed for the northern hemisphere. However, similar proxies are very limited for South America, particularly for high altitudes where, for example, tree-ring chronologies are not available and instrumental records are very limited. Consequently, our knowledge of high altitude climate changes in arid regions of the Peruvian Andes mainly relies on ice-core and lake deposit studies. In our study, we used a new alternative proxy for interpretation of palaeoclimate conditions based on a peat core taken from the Carhuasanta Valley at the foot of Nevado Mismi in the southern Peruvian Andes (15° 30'S, 71° 43'W, 4809m a.s.l.). The stable carbon isotope composition (δ13C) of Distichia peat reflects mainly the relative variation of the mean air temperature during subsequent growing seasons [3], and allows reconstructions of palaeotemperature changes. In contrast, peat organic carbon concentration (C % wt) records mainly wetness in the valley, directly corresponding to the changes in runoff in the upper part of the catchment. The most prominent climate changes recorded in the peat over last 4ka occurred between 3040 and 2750 cal. yrs BP. The initial warming turned to a very rapid cooling to temperatures at least 2° C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP, when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes that match the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years, when

A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by shallow firn core from Monte San Valentin (Northern patagonia Icefield, Chile)

DEFF Research Database (Denmark)

Vimeux, F.; de Angelis, M.; Ginot, P.

2008-01-01

temperature is -11.9°C at 10-m depth allowing to expect well preserved both chemical and isotopic signals, unperturbed by water percolation. The dating of the core, on the basis of a multi-proxy approach combining annual layer counting and radionuclide measurements, shows that past environment and climate can......The study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid......-latitudes in the Southern Hemisphere. In this framework, a 15.3-m long shallow firn core has been extracted in March 2005 from the summit plateau of Monte San Valentín (3747 m, 46°35'S, 73°19'W) in the Northern Patagonia Icefield to test its potential for paleoclimate and paleoenvironmental reconstructions. The firn...

Why Drill More than One Ice Core? Paleoclimate Reconstruction along a Vertical Transect in the Saint Elias Mountains

Science.gov (United States)

Wake, C. P.; Yalcin, K.; Kreutz, K. J.; Mayewski, P. A.; Fisher, D.; Holdsworth, G.

2004-05-01

The Arctic represents one of the key regions on Earth in our efforts to document and understand global change. The St. Elias mountain range in the southwestern Yukon Territory has recently been the focus of an international ice core research.. The broad elevational extent of snow accumulation zones in this region (ranging from 2500 to 5300 m asl) allows for the detailed investigation of environmental change extending from the planetary boundary layer through to the free troposphere via the collection and analysis of ice cores from different elevations. Multi-parameter, high resolution glaciochemical records are currently available from the Northwest Col on Mt. Logan (5340 m asl, 103 m deep; 270 year record;) and from three cores recovered from the Eclipse Icefield (3107 m asl) in 1996 (160 m deep; 100 year record) and in 2002 (345 m and 140 m deep). Snow accumulation rates at Eclipse are about 5 times larger than the summit average of 0.30 m water equivalent. Despite their close proximity, the climate signals recorded on the summit of Mt. Logan also differ from those at Eclipse. For example, while the Mt. Logan record shows no increase in sulfate or nitrate deposition over the past 100 years, all three Eclipse cores shows a clear increase in nitrate and sulfate deposition beginning in the late 1940s due to an increase in anthropogenic emissions in Eurasia during this time period. Over the last century, the sulfate time-series from Eclipse records from 32 discrete volcanic events, primarily from Alaskan, Aleutian, or Kamchatkan eruptions, while the summit site only records 8 volcanic events. The Eclipse summer d18O record displays a significant positive relationship with summer temperatures at both coastal and interior Alaskan sites, while the Mt. Logan d18O time-series does not correlate well with instrumental temperature records or most circum-Arctic paleoclimate records. Conversely, the summit ice core accumulation time-series strongly correlates with

Paleoclimate records at high latitude in Arctic during the Paleogene

Science.gov (United States)

Salpin, Marie; Schnyder, Johann; Baudin, François; Suan, Guillaume; Labrousse, Loïc; Popescu, Speranta; Suc, Jean-Pierre

2015-04-01

Paleoclimate records at high latitude in Arctic during the Paleogene SALPIN Marie1,2, SCHNYDER Johann1,2, BAUDIN François1,2, SUAN Guillaume3, LABROUSSE Loïc1,2, POPESCU Speranta4, SUC Jean-Pierre1,4 1: Sorbonne Universités, UPMC Univ Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005, Paris, France 2: CNRS, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005 Paris, France 3: UCB Lyon 1, UMR 5276, LGLTPE, 69622 Villeurbanne Cedex, France 4: GEOBIOSTRATDATA.CONSULTING, 385 Route du Mas Rillier 69140 Rillieux la Pape, France The Paleogene is a period of important variations of the Earth climate system either in warming or cooling. The climatic optima of the Paleogene have been recognized both in continental and marine environment. This study focus on high latitudes of the northern hemisphere, in the Arctic Basin. The basin has had an influence on the Cenozoic global climate change according to its polar position. Is there a specific behaviour of the Arctic Basin with respect to global climatic stimuli? Are there possible mechanisms of coupling/decoupling of its dynamics with respect to the global ocean? To answer these questions a unique collection of sedimentary series of Paleogene age interval has been assembled from the Laurentian margin in Northern Yukon (Canada) and from the Siberian margin (New Siberian Islands). Selected continental successions of Paleocene-Eocene age were used to study the response of the Arctic system to known global events, e.g. the climatic optima of the Paleogene (the so-called PETM, ETM2 or the Azolla events). Two sections of Paleocene-Eocene age were sampled near the Mackenzie delta, the so-called Coal Mine (CoMi) and Caribou Hills (CaH) sections. The aim of the study is to precise the climatic fluctuations and to characterise the source rock potential of the basin, eventually linked to the warming events. This study is based on data of multi-proxy analyses: mineralogy on bulk and clay

Nursing patients with acute chest pain: practice guided by the Prince Edward Island conceptual model for nursing.

Science.gov (United States)

Blanchard, Janelle F; Murnaghan, Donna A

2010-01-01

Current research suggests that pain is a relatively common phenomenon with 60-90% of patients presenting to emergency departments reporting pain (e.g., chest pain, trauma, extremity fractures and migraine headache) that require treatment [Hogan, S.L., 2005. Patient satisfaction with pain management in the emergency department. Advanced Emergency Nursing Journal 27(4), 284-294]. This article explores the use of conceptual theoretical empirical (C-T-E) framework to guide a senior nursing student in a case study of patient with chest pain. The Middle Range Theory of Pain described by Good [Good, M., 1998. A middle-range theory of acute pain management: use in research. Nursing Outlook 46(3), 120-124] and Melzack's [Melzack, R., 1987. The short-form McGill pain questionnaire. Pain, 30, 191-197] short form McGill pain questionnaire were applied along with the Prince Edward Island conceptual model (PEICM) for nursing. Results indicate that the nursing student increased her ability to work in partnership, assess relevant and specific information, and identify a number of strategies to help the patient achieve pain control by using a complement of pharmacological and non-pharmacological interventions. Moreover, the C-T-E approach provided an organized and systematic theoretical approach for the nursing student to assist a patient in pain control.

Development, validation, and factorial comparison of the McGill Self-Efficacy of Learners For Inquiry Engagement (McSELFIE) survey in natural science disciplines

Science.gov (United States)

Ibrahim, Ahmed; Aulls, Mark W.; Shore, Bruce M.

2016-11-01

Sociocognitive theory [Bandura, A. (1986). Social foundations of thought and action: A social cognitive theory. Englewood Cliffs, NJ: Prentice Hall; Bandura, A. (1989). Human agency in social cognitive theory. American Psychologist, 44, 1175-1184. doi:10.1037/0003-066x.44.9.1175; Bandura, A. (1991). Social cognitive theory of self-regulation. Organizational Behavior and Human Decision Processes, 50, 248-287. doi:10.1016/0749-5978(91)90022-L] accords high importance to the mechanisms of human agency and how they are exercised through self-efficacy. In this paper, we developed and validated the McGill Self-Efficacy For Inquiry Engagement (McSELFIE) instrument with undergraduate students in natural science disciplines. We defined inquiry engagement as carrying out the practices of science (POS) that are supported by students' personality characteristics (SPCs) and that result in achieving inquiry-learning outcomes (ILOs). Based on these theoretical perspectives, the McSELFIE is a 60-item, learner-focused survey that addresses three components that are theoretically important for engaging in scientific inquiry: (a) SPCs, (b) ILOs, and (c) POS. Evidence for construct and content validity were obtained by using experts' judgments and confirmatory factor analysis with a sample of 110 undergraduate students enrolled in science disciplines. Internal consistency of the factors and instrument was also examined. The McSELFIE instrument is a reliable and valid instrument for measuring science undergraduate students' self-efficacy for inquiry engagement. Matched pairs analyses were conducted among the instruments' factors. Students reported the highest self-efficacy for openness, applying knowledge, and carrying out investigations. Students reported the lowest self-efficacy for extraversion, understanding metacognitive knowledge, and planning investigations. Theoretical and practical implications are discussed.

A lacustrine record from Lop Nur, Xinjiang, China: Implications for paleoclimate change during Late Pleistocene

Science.gov (United States)

Chao, L.; Zicheng, P.; Dong, Y.; Weiguo, L.; Zhaofeng, Z.; Jianfeng, H.; Chenlin, C.

2009-01-01

Climate variability during the Late Pleistocene is studied from the proxies in core CK-2 drilled from the Luobei Depression (91??03???E, 40??47???N), Lop Nur in the eastern Tarim Basin, Xinjiang, China. Geophysical and geochemical properties, including magnetic susceptibility, granularity, chroma, carbonate content, loss on ignition and trace elements, have been determined to reconstruct the environmental evolution of the area during 32-9 ka BP. The chronology is established by uranium-thorium disequilibrium dating techniques. Our data suggest four paleoclimate stages, indicating glacial variations between cold-humid and warm-arid environments. A period of extreme humidity occurred during 31,900-19,200 yr BP is attributed the last glacial maximum (LGM). The period was followed by a warm-arid episode during 19,200-13,500 yr BP. Then a cold-humid interval during 13,500-12,700 yr BP may correspond to another cooling phases at high latitudes of the Northern Hemisphere. The last stage from 12,700 to 9000 yr BP has a trend that the climate turned warm and arid. The Lop Nur region is characterized by particularly humid stadials and arid interstadials. The climate variability in Lop Nur was constrained by global climate change because it is correlated with Dansgaard-Oeschger and Heinrich events, which were observed at the northern high latitudes. The synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the Lop Nur region. A probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity. ?? 2008 Elsevier Ltd.

How cold was Europe at the Last Glacial Maximum? A synthesis of the progress achieved since the first PMIP model-data comparison

Directory of Open Access Journals (Sweden)

G. Ramstein

2007-06-01

Full Text Available The Last Glacial Maximum has been one of the first foci of the Paleoclimate Modelling Intercomparison Project (PMIP. During its first phase, the results of 17 atmosphere general circulation models were compared to paleoclimate reconstructions. One of the largest discrepancies in the simulations was the systematic underestimation, by at least 10°C, of the winter cooling over Europe and the Mediterranean region observed in the pollen-based reconstructions. In this paper, we investigate the progress achieved to reduce this inconsistency through a large modelling effort and improved temperature reconstructions. We show that increased model spatial resolution does not significantly increase the simulated LGM winter cooling. Further, neither the inclusion of a vegetation cover compatible with the LGM climate, nor the interactions with the oceans simulated by the atmosphere-ocean general circulation models run in the second phase of PMIP result in a better agreement between models and data. Accounting for changes in interannual variability in the interpretation of the pollen data does not result in a reduction of the reconstructed cooling. The largest recent improvement in the model-data comparison has instead arisen from a new climate reconstruction based on inverse vegetation modelling, which explicitly accounts for the CO₂ decrease at LGM and which substantially reduces the LGM winter cooling reconstructed from pollen assemblages. As a result, the simulated and observed LGM winter cooling over Western Europe and the Mediterranean area are now in much better agreement.

Historical and idealized climate model experiments: an EMIC intercomparison

DEFF Research Database (Denmark)

Eby, M.; Weaver, A. J.; Alexander, K.

2012-01-01

Both historical and idealized climate model experiments are performed with a variety of Earth System Models of Intermediate Complexity (EMICs) as part of a community contribution to the Intergovernmental Panel on Climate Change Fifth Assessment Report. Historical simulations start at 850 CE...... and continue through to 2005. The standard simulations include changes in forcing from solar luminosity, Earth's orbital configuration, CO2, additional greenhouse gases, land-use, and sulphate and volcanic aerosols. In spite of very different modelled pre-industrial global surface air temperatures...... the Medieval Climate Anomaly and the Little Ice Age estimated from paleoclimate reconstructions. This in turn could be a result of errors in the reconstructions of volcanic and/or solar radiative forcing used to drive the models or the incomplete representation of certain processes or variability within...

Skill and reliability of climate model ensembles at the Last Glacial Maximum and mid-Holocene

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J. C. Hargreaves

2013-03-01

Full Text Available Paleoclimate simulations provide us with an opportunity to critically confront and evaluate the performance of climate models in simulating the response of the climate system to changes in radiative forcing and other boundary conditions. Hargreaves et al. (2011 analysed the reliability of the Paleoclimate Modelling Intercomparison Project, PMIP2 model ensemble with respect to the MARGO sea surface temperature data synthesis (MARGO Project Members, 2009 for the Last Glacial Maximum (LGM, 21 ka BP. Here we extend that work to include a new comprehensive collection of land surface data (Bartlein et al., 2011, and introduce a novel analysis of the predictive skill of the models. We include output from the PMIP3 experiments, from the two models for which suitable data are currently available. We also perform the same analyses for the PMIP2 mid-Holocene (6 ka BP ensembles and available proxy data sets. Our results are predominantly positive for the LGM, suggesting that as well as the global mean change, the models can reproduce the observed pattern of change on the broadest scales, such as the overall land–sea contrast and polar amplification, although the more detailed sub-continental scale patterns of change remains elusive. In contrast, our results for the mid-Holocene are substantially negative, with the models failing to reproduce the observed changes with any degree of skill. One cause of this problem could be that the globally- and annually-averaged forcing anomaly is very weak at the mid-Holocene, and so the results are dominated by the more localised regional patterns in the parts of globe for which data are available. The root cause of the model-data mismatch at these scales is unclear. If the proxy calibration is itself reliable, then representativity error in the data-model comparison, and missing climate feedbacks in the models are other possible sources of error.

Model, Proxy and Isotopic Perspectives on the East African Humid Period

Science.gov (United States)

Tierney, Jessica E.; Lewis, Sophie C.; Cook, Benjamin I.; LeGrande, Allegra N.; Schmidt, Gavin A.

2011-01-01

Both North and East Africa experienced more humid conditions during the early and mid-Holocene epoch (11,000-5000yr BP; 11-5 ka) relative to today. The North African Humid Period has been a major focus of paleoclimatic study, and represents a response of the hydrological cycle to the increase in boreal summer insolation and associated ocean, atmosphere and land surface feedbacks. Meanwhile, the mechanisms that caused the coeval East African Humid Period are poorly understood. Here, we use results from isotopeenabled coupled climate modeling experiments to investigate the cause of the East African Humid Period. The modeling results are interpreted alongside proxy records of both water balance and the isotopic composition of rainfall. Our simulations show that the orbitally-induced increase in dry season precipitation and the subsequent reduction in precipitation seasonality can explain the East African Humid Period, and this scenario agrees well with regional lake level and pollen paleoclimate data. Changes in zonal moisture flux from both the Atlantic and Indian Ocean account for the simulated increase in precipitation from June through November. Isotopic paleoclimate data and simulated changes in moisture source demonstrate that the western East African Rift Valley in particular experienced more humid conditions due to the influx of Atlantic moisture and enhanced convergence along the Congo Air Boundary. Our study demonstrates that zonal changes in moisture advection are an important determinant of climate variability in the East African region.

MODEL RECONSTRUCTION OF THE VEGETATION COVER OF THE SOUTH OF THE WEST SIBERIAN PLAIN FROM THE LATE PALEOLITHIC PERIOD UNTIL THE LATE XIX CENTURY

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М. А. Kharitonenkov

2016-06-01

Full Text Available Model reconstruction of vegetation cover of the south of the West Siberian Plain from the late Pleistocene to the modern era has been carried out on the basis of the associated chronological analysis of paleontological, archaeological and paleoclimate data. We have determined the starting point of active vegetation transformation in the south of the West Siberian Plain as a result of tradition-bound exploitation of natural resources. Periods of maximum anthropogenic load – peak and relative recession – on vegetation cover, acting as a further determinant factor, have been determined in this study for the first time. Comprehensive analysis and new understanding of palynological, paleozoological, archaeological and paleoclimate data in terms of theoretical synecology confirmed the notions on the determinant role of the anthropogenic factor in the transformation of the Pleistocene forest-meadow-steppe vegetation into contemporary communities of the southern taiga, the subtaiga and the forest-steppe of the West Siberian Plain.

Geochemistry of buried river sediments from Ghaggar Plains, NW India: Multi-proxy records of variations in provenance, paleoclimate, and paleovegetation patterns in the Late Quaternary

DEFF Research Database (Denmark)

Singh, Ajit; Paul, Debajyoti; Sinha, Rajiv

2016-01-01

We report the first geochemical record in two drill-sediment cores from a buried channel in the Ghaggar Plains of NW India, which are used to infer variations in provenance, paleoclimate, and paleovegetation in the locality during the Late Quaternary. Aeolian sediments (~150 ka) in both the cores...... are overlain by fluvial sediments (~75 ka-recent). Major oxide compositions of the core sediments (n = 35) generally vary between that observed for the modern-day Ghaggar/Sutlej and Yamuna river sand. The isotopic composition (87Sr/86Sr: 0.7365 to 0.7783 and εNd: -14.6 to -19.0) of core sediments (n = 18......) suggest binary mixing of sediments from compositionally distinct Higher Himalaya (HH) and Lesser Himalaya (LH) endmembers in the catchment, and support involvement of a river system originating in the Himalayan hinterland. Distinctly higher 87Sr/86Sr and lower εNd in the core sediments during glacial...

Global climate change model natural climate variation: Paleoclimate data base, probabilities and astronomic predictors

Energy Technology Data Exchange (ETDEWEB)

Kukla, G.; Gavin, J. [Columbia Univ., Palisades, NY (United States). Lamont-Doherty Geological Observatory

1994-05-01

This report was prepared at the Lamont-Doherty Geological Observatory of Columbia University at Palisades, New York, under subcontract to Pacific Northwest Laboratory it is a part of a larger project of global climate studies which supports site characterization work required for the selection of a potential high-level nuclear waste repository and forms part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work under the PASS Program is currently focusing on the proposed site at Yucca Mountain, Nevada, and is under the overall direction of the Yucca Mountain Project Office US Department of Energy, Las Vegas, Nevada. The final results of the PNL project will provide input to global atmospheric models designed to test specific climate scenarios which will be used in the site specific modeling work of others. The primary purpose of the data bases compiled and of the astronomic predictive models is to aid in the estimation of the probabilities of future climate states. The results will be used by two other teams working on the global climate study under contract to PNL. They are located at and the University of Maine in Orono, Maine, and the Applied Research Corporation in College Station, Texas. This report presents the results of the third year`s work on the global climate change models and the data bases describing past climates.

Connecting Paleo and Modern Oceanographic Data to Understand Atlantic Meridional Overturning Circulation Over Decades to Centuries

Science.gov (United States)

Kilbourne, Hali; Klockmann, Marlene; Moreno-Chamarro, Eduardo; Ortega, Pablo; Romanou, Anastasia; Srokosz, Meric; Szuts, Zoltan; Thirumalai, Kaustubh; Hall, Ian; Heimbach, Patrick;

High-resolution paleoclimate records of Holocene hydroclimatic variability in the Eastern Colombian Andes from Lago de Tota

Science.gov (United States)

Ahmed, M. N.; Bird, B. W.; Escobar, J.; Polissar, P. J.

2017-12-01

The Northern Hemisphere (NH) South American Monsoon (SAM) is a significant source of precipitation for the North Andes (north of 0˚) and has major control over regional hydroclimate variability. Holocene-length histories of NH SAM variability are few compared to the Southern Hemisphere (SH), limiting understanding of how these systems are connected on orbital and shorter timescales. Here, we present multi-proxy lake-sediment-based paleoclimate and paleohydrologic reconstructions from Lago de Tota, Colombia, using sedimentological, geochemical and leaf-wax hydrogen isotopic indicators from radiometically dated cores. The results indicate periods of wet and dry climate phases during the past 9000 BP with an average Holocene sedimentation rate 33cm/kyr. An increase in total organic matter (TOM) content and finer grain-size distributions was observed from 8000 to 3200 BP, suggesting a period of high lake level. This was followed by lower TOM and coarser grain sizes, suggesting lower lake levels from 3200 BP to the present. Although Tota's lake level pattern is antiphased with other lake level reconstructions from the NH and SH Andes, it is consistent with hypothesized changes in atmospheric convection over the Andes during the Holocene and the way in which they would be modified by the so-called dry island effect in the Colombian Andes. This suggests that a common forcing mechanism can be invoked to explain differing millennial-scale Andean hydroclimate changes, namely atmospheric convection. Orbital and Pacific atmosphere-forcing are therefore likely to have played a significant role in driving pan-Andean hydroclimate variability based on their inter-hemispheric influence on Andean convection.

Comparison of the Effects of Dry Cupping and Acupressure at Acupuncture Point (BL23) on the Women with Postpartum Low Back Pain (PLBP) Based on Short Form McGill Pain Questionnaires in Iran: A Randomized Controlled Trial.

Science.gov (United States)

Yazdanpanahi, Zahra; Ghaemmaghami, Mehrnoush; Akbarzadeh, Marzieh; Zare, Najaf; Azisi, Amir

2017-06-01

Objective: To evaluate the effects of acupuncture branches on postpartum low back pain severity among the primiparous subjects visiting the selected educational centers affiliated to Shiraz University of Medical Sciences, Shiraz, Iran. Materials and methods: This clinical trial was conducted on 150 (each group of 50 people) cases in 2012. Cupping therapy was done every other day in four 15-20 minute sessions a week. Besides, acupressure was applied according to the circular model for 20 minutes. The patients filled out the short form McGill Pain Questionnaires. Then, the data were analyzed using the SPSS statistical software (v. 16) and repeated measurements and Chi-square tests. Results: In the cupping group, the mean difference of postpartum Low Back Pain intensity reached from 31.8 ± 10.8 before the intervention to 9.0 ± 6.7, 7.5 ± 6.6, and 4.1 ± 3.6 immediately, 24 hours, and 2 weeks after the intervention, respectively and the results of repeated measures ANOVA showed a significant difference between the three follow-up periods (p < 0.05). On the other hand, this measure reached from 31.1 ± 11.0 before the intervention to 22.1 ± 7.3, 16.2±6.0, and 11.7 ± 5.3 immediately, 24 hours, and 2 weeks after the intervention, respectively in the acupressure group. Conclusion: The study results showed that these modalities could sedate the pain. Therefore, they can be applied as efficient treatments for reducing the low back pain.

Comparison of the Effects of Dry Cupping and Acupressure at Acupuncture Point (BL23 on the Women with Postpartum Low Back Pain (PLBP Based on Short Form McGill Pain Questionnaires in Iran: A Randomized Controlled Trial

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Zahra Yazdanpanahi

2017-10-01

Full Text Available Objective: To evaluate the effects of acupuncture branches on postpartum low back pain severity among the primiparous subjects visiting the selected educational centers affiliated to Shiraz University of Medical Sciences, Shiraz, Iran.Materials and methods: This clinical trial was conducted on 150 (each group of 50 people cases in 2012. Cupping therapy was done every other day in four 15-20 minute sessions a week. Besides, acupressure was applied according to the circular model for 20 minutes. The patients filled out the short form McGill Pain Questionnaires. Then, the data were analyzed using the SPSS statistical software (v. 16 and repeated measurements and Chi-square tests.Results: In the cupping group, the mean difference of postpartum Low Back Pain intensity reached from 31.8 ± 10.8 before the intervention to 9.0 ± 6.7, 7.5 ± 6.6, and 4.1 ± 3.6 immediately, 24 hours, and 2 weeks after the intervention, respectively and the results of repeated measures ANOVA showed a significant difference between the three follow-up periods (p < 0.05. On the other hand, this measure reached from 31.1 ± 11.0 before the intervention to 22.1 ± 7.3, 16.2±6.0, and 11.7 ± 5.3 immediately, 24 hours, and 2 weeks after the intervention, respectively in the acupressure group.Conclusion: The study results showed that these modalities could sedate the pain. Therefore, they can be applied as efficient treatments for reducing the low back pain. 

Reconstruction of spatio-temporal temperature from sparse historical records using robust probabilistic principal component regression

OpenAIRE

Tipton, John; Hooten, Mevin; Goring, Simon

2017-01-01

Scientific records of temperature and precipitation have been kept for several hundred years, but for many areas, only a shorter record exists. To understand climate change, there is a need for rigorous statistical reconstructions of the paleoclimate using proxy data. Paleoclimate proxy data are often sparse, noisy, indirect measurements of the climate process of interest, making each proxy uniquely challenging to model statistically. We reconstruct spatially explicit temper...

Hydroclimate variability in Scandinavia over the last millennium - insights from a climate model-proxy data comparison

Science.gov (United States)

Seftigen, Kristina; Goosse, Hugues; Klein, Francois; Chen, Deliang

2017-12-01

The integration of climate proxy information with general circulation model (GCM) results offers considerable potential for deriving greater understanding of the mechanisms underlying climate variability, as well as unique opportunities for out-of-sample evaluations of model performance. In this study, we combine insights from a new tree-ring hydroclimate reconstruction from Scandinavia with projections from a suite of forced transient simulations of the last millennium and historical intervals from the CMIP5 and PMIP3 archives. Model simulations and proxy reconstruction data are found to broadly agree on the modes of atmospheric variability that produce droughts-pluvials in the region. Despite these dynamical similarities, large differences between simulated and reconstructed hydroclimate time series remain. We find that the GCM-simulated multi-decadal and/or longer hydroclimate variability is systematically smaller than the proxy-based estimates, whereas the dominance of GCM-simulated high-frequency components of variability is not reflected in the proxy record. Furthermore, the paleoclimate evidence indicates in-phase coherencies between regional hydroclimate and temperature on decadal timescales, i.e., sustained wet periods have often been concurrent with warm periods and vice versa. The CMIP5-PMIP3 archive suggests, however, out-of-phase coherencies between the two variables in the last millennium. The lack of adequate understanding of mechanisms linking temperature and moisture supply on longer timescales has serious implications for attribution and prediction of regional hydroclimate changes. Our findings stress the need for further paleoclimate data-model intercomparison efforts to expand our understanding of the dynamics of hydroclimate variability and change, to enhance our ability to evaluate climate models, and to provide a more comprehensive view of future drought and pluvial risks.

Carbon isotopes: variations of their natural abundance. Application to correction of radiocarbon dates, to the study of plant metabolism and to paleoclimate

International Nuclear Information System (INIS)

Lerman, J.C.

1974-01-01

The radiocarbon activity of contemporaneous samples shows: i) variations in the specific activity of the atmospheric C14, which varies with time and locality. ii) variations due to isotope discrimination, or fractionation, of the carbon isotope ratio during the fixation of carbon by organic or inorganic matter. The variation in the atmospheric concentration of carbon 14 as observed in tree rings are synchronous and of the same amplitude for both hemispheres (southern and northern). A curve for correction of radiocarbon dates of the southern hemisphere is given for the last 500 years. The activity of atmospheric radiocarbon as measured in tree rings varies with latitude, showing a difference of (4.5+-1) per mille between the northern and southern hemispheres, the latter having lower concentration of radiocarbon, equivalent to an age difference of about 35 years. This variation can be explained by a larger exchange of carbon 14 between the atmosphere and the sea in the southern hemisphere to a larger free ocean surface (40%) and a higher agitation by winds. The main differences of the isotope fractionation by different types of plants are correlated to their photosynthetic pathways and thus to the enzyme which effects the primary fixation of carbon. The delta C13 values can be used as basis of a paleoclimate indicator [fr

IDRC and McGill University

International Development Research Centre (IDRC) Digital Library (Canada)

is leading research into psychological ... and cultural expressions of distress, ... 6. 5. 2. 7. 1. IDRC. INTERNATIONAL DEVELOPMENT RESEARCH CENTRE ... scientific director of the Douglas Mental Health Institute. R. A. D. IO. N. ED. ER. LA.

A formational model for the polygonal terrains of Mars: Taking a crack at the genesis of the Martian polygons

Science.gov (United States)

Wenrich, M. L.; Christensen, P. R.

1993-01-01

The mechanism for the genesis of the polygonal terrains in Acidalia and Utopia Planitia has long been sought: however, no completely satisfying model was put forth that characterizes the evolution of these complexly patterned terrains. The polygons are roughly hexagonal but some are not entirely enclosed by fractures. These polygonal features range in widths from approximately 5 to 20 km. Several origins were proposed that describe the polygon borders as desiccation cracks, columnar jointing in a cooled lava, or frost-wedge features. These tension-induced cracking hypotheses were addressed by Pechmann, who convincingly disputes these mechanisms of formation based on scale magnitude difficulties and morphology. Pechmann suggests instead that the cracks delineating the 5-20-km-wide polygons on the northern plains of Mars are graben resulting from deep-seated, uniform, horizontal tension. The difficulty with this hypothesis is that no analogous polygonal forms are known to have originated by tectonism on Earth. McGill and Hills propose that the polygonal terrains on Mars resulted from either rapid desiccation of sediments or cooling of volcanics coupled with differential compaction of the material over a buried irregular topographic surface. They suggest that fracturing was enhanced over the areas of positive relief and was suppressed above the topographic lows. McGill and Hills suggest that the spacing of the topographic highs primarily controls the size of the Martian polygons and the physics of the shrinkage process is a secondary concern. Ray et. al. conducted a terrestrial study of patterned ground in periglacial areas of the U.S. to determine the process responsible for polygonal ground formation. They developed a model for polygon formation in which convection of seasonal melt water above a permafrost layer, driven by an unstable density stratification, differentially melts the permafrost interface, causing it to become undulatory.

Quality of life in patients with advanced cancer at the end of life as measured by the McGill quality of life questionnaire: a survey in China.

Science.gov (United States)

Cui, Jing; Fang, Fang; Shen, Fengping; Song, Lijuan; Zhou, Lingjun; Ma, Xiuqiang; Zhao, Jijun

2014-11-01

Quality of life (QOL) is the main outcome measure for patients with advanced cancer at the end of life. The McGill Quality of Life Questionnaire (MQOL) is designed specifically for palliative care patients and has been translated and validated in Hong Kong and Taiwan. This study aimed to investigate the QOL of patients with advanced cancer using the MQOL-Taiwan version after cultural adaptation to the Chinese mainland. A cross-sectional survey design was used. QOL data from patients with advanced cancer were gathered from 13 hospitals including five tertiary hospitals, six secondary hospitals, and community health care service centers in Shanghai and analyzed. QOL was assessed using the MQOL-Chinese version. Statistical analyses were performed using descriptive statistics, multiple regression analysis, and Spearman rank correlation analysis. A total of 531 cancer patients (297 male and 234 female) in 13 hospitals were recruited into the study and administered the MQOL-Chinese. The score of the support subscale was highest (6.82), and the score of the existential well-being subscale was the lowest (4.65). The five physical symptoms most frequently listed on the MQOL-Chinese were pain, loss of appetite, fatigue, powerless, and dyspnea. Participants' sex, educational level, number of children, disclosure of the disease, and hospital size were associated with their overall QOL. The Spearman rank correlation analysis found that Karnofsky Performance Status scores correlated with the MQOL-Chinese single-item score, physical well-being, psychological well-being, existential well-being, and support domains (P patients with advanced cancer. The association between the characteristics of patients, Karnofsky Performance Status, and their QOL also was identified. Copyright © 2014 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

A stochastic vision of the paleoclimate. Modelling and predictibility

Directory of Open Access Journals (Sweden)

Ionel HAIDU

2014-11-01

Full Text Available The objective of the paper is related to the use of stochastic methods to appreciate if the recent climate trend is similar to the decennial trends of the last thousands years.If not, it means that the present climate change is unprecedented.If yes, it means that the extraordinary climatic events of the recent years are a natural expression of climate variability, but the memory of several generations and of instrumental series, more than 100 years old, cannot point it out. The first hypothesis is an “alarming” possibility, while the latter is a “relaxing” one.

Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan

International Nuclear Information System (INIS)

Vladimir Aizen; Donald Bren; Karl Kreutz; Cameron Wake

2001-01-01

While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with the United State Geological Survey's (USGS) Global Environmental Research Program which began studying radionuclide deposition in mid-latitude glaciers in 1995

Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan

Energy Technology Data Exchange (ETDEWEB)

Vladimir Aizen; Donald Bren; Karl Kreutz; Cameron Wake

2001-05-30

While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with the United State Geological Survey's (USGS) Global Environmental Research Program which began studying radionuclide deposition in mid-latitude glaciers in 1995.

Sensitivity of leaf size and shape to climate: Global patterns and paleoclimatic applications

Science.gov (United States)

Peppe, D.J.; Royer, D.L.; Cariglino, B.; Oliver, S.Y.; Newman, S.; Leight, E.; Enikolopov, G.; Fernandez-Burgos, M.; Herrera, F.; Adams, J.M.; Correa, E.; Currano, E.D.; Erickson, J.M.; Hinojosa, L.F.; Hoganson, J.W.; Iglesias, A.; Jaramillo, C.A.; Johnson, K.R.; Jordan, G.J.; Kraft, N.J.B.; Lovelock, E.C.; Lusk, C.H.; Niinemets, U.; Penuelas, J.; Rapson, G.; Wing, S.L.; Wright, I.J.

2011-01-01

Paleobotanists have long used models based on leaf size and shape to reconstruct paleoclimate. However, most models incorporate a single variable or use traits that are not physiologically or functionally linked to climate, limiting their predictive power. Further, they often underestimate paleotemperature relative to other proxies. Here we quantify leaf-climate correlations from 92 globally distributed, climatically diverse sites, and explore potential confounding factors. Multiple linear regression models for mean annual temperature (MAT) and mean annual precipitation (MAP) are developed and applied to nine well-studied fossil floras. We find that leaves in cold climates typically have larger, more numerous teeth, and are more highly dissected. Leaf habit (deciduous vs evergreen), local water availability, and phylogenetic history all affect these relationships. Leaves in wet climates are larger and have fewer, smaller teeth. Our multivariate MAT and MAP models offer moderate improvements in precision over univariate approaches (??4.0 vs 4.8??C for MAT) and strong improvements in accuracy. For example, our provisional MAT estimates for most North American fossil floras are considerably warmer and in better agreement with independent paleoclimate evidence. Our study demonstrates that the inclusion of additional leaf traits that are functionally linked to climate improves paleoclimate reconstructions. This work also illustrates the need for better understanding of the impact of phylogeny and leaf habit on leaf-climate relationships. ?? 2011 The Authors. New Phytologist ?? 2011 New Phytologist Trust.

Tropical Hydroclimate Change during Heinrich Stadial 1: An Integrative Proxy-Model Synthesis

Science.gov (United States)

Lawman, A. E.; Sun, T.; Shanahan, T. M.; Di Nezio, P. N.; Gomez, K.; Piatrunia, N.; Sun, C.; Wu, X.; Kageyama, M.; Merkel, U.; Otto-Bliesner, B. L.; Abe-Ouchi, A.; Lohmann, G.; Singarayer, J. S.

2017-12-01

We explore the response of tropical climate to abrupt cooling of the North Atlantic (NA) during Heinrich Stadial 1 (HS1) combining paleoclimate proxies with model simulations. A total of 146 published paleoclimate records from tropical locations are used to categorize whether HS1 was wetter, drier, or unchanged relative to a deglacial baseline state. Only records with sufficient resolution to resolve HS1 and sufficient length to characterize the deglacial trend are considered. This synthesis reveals large-scale patterns of hydroclimate change relative to glacial conditions, confirming previously reported weaker Indian summer monsoon, a wetter southern Africa, and drying over the Caribbean. Our synthesis also reveals large-scale drying over the Maritime continent as well as wetter conditions in northern Australia and southern tropical South America. Our reinterpretation of the available proxy data reveals far more complexity and uncertainties for equatorial East Africa, a region that appears to straddle a pattern of dryer conditions to the north and wetter conditions to the south. Overall, these patterns of hydroclimate change depart from a southward shift of the Inter Tropical Convergence Zone (ITCZ), particularly outside the tropical Atlantic. We explore mechanisms driving these changes using a multi-model ensemble of "hosing" simulations performed relative to glacial conditions. The models show robust weakening of the Afro-Asian Monsoon, which we attribute to ventilation of colder mid-latitude air. Not all models simulate the remaining patterns inferred from the proxy data. The best-agreeing models indicate that cooling over the tropical NA and the Caribbean may be essential to communicate the response to the global tropics. This response can induce warming over the tropical South Atlantic via the wind-evaporation-SST feedback, driving wetter conditions in South Africa and tropical South America. Cooling over the Caribbean is communicated to the Pacific over the

Greenhouse effect

International Nuclear Information System (INIS)

1992-01-01

This special issue is devoted to the greenhouse effect and reviews the possible climate change by mankind, paleoclimates, climate models, measurement of terrestrial temperature, CO 2 concentration and energy policy

Reduced ENSO Variability at the LGM Revealed by an Isotope-Enabled Earth System Model

Science.gov (United States)

Zhu, Jiang; Liu, Zhengyu; Brady, Esther; Otto-Bliesner, Bette; Zhang, Jiaxu; Noone, David; Tomas, Robert; Nusbaumer, Jesse; Wong, Tony; Jahn, Alexandra;

Model of Team Organization and Behavior and Team Description Method

Science.gov (United States)

1984-10-01

PERFORMING ORG& REPORT’ NUMBER 7.AUTHIOR(&) 0. CONTRACT OR GRANT NUMOSR(ej J. Thomas Roth Rohn J. Hritz HDA 903-81-C-0198: VEa Donald W. McGill 9...team descriptions are included, acid procedures for data recording are provided. 4q-4 4 iv, G OP S• . . • ,," $1 . . ’ __ _ _ _ ’ / . • , Utilization...Listing of thi! number acid identification of the roles adopted by team members in the actual team structure, along with KOS and primary equipment

Subtask 2.4 - Integration and Synthesis in Climate Change Predictive Modeling

Energy Technology Data Exchange (ETDEWEB)

Jaroslav Solc

2009-06-01

The Energy & Environmental Research Center (EERC) completed a brief evaluation of the existing status of predictive modeling to assess options for integration of our previous paleohydrologic reconstructions and their synthesis with current global climate scenarios. Results of our research indicate that short-term data series available from modern instrumental records are not sufficient to reconstruct past hydrologic events or predict future ones. On the contrary, reconstruction of paleoclimate phenomena provided credible information on past climate cycles and confirmed their integration in the context of regional climate history is possible. Similarly to ice cores and other paleo proxies, acquired data represent an objective, credible tool for model calibration and validation of currently observed trends. It remains a subject of future research whether further refinement of our results and synthesis with regional and global climate observations could contribute to improvement and credibility of climate predictions on a regional and global scale.

The PMIP4 contribution to CMIP6 – Part 2 : Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations

NARCIS (Netherlands)

Otto-bliesner, Bette L.; Braconnot, Pascale; Harrison, Sandy P.; Lunt, Daniel J.; Abe-Ouchi, Ayako; Albani, Samuel; Bartlein, Patrick J.; Capron, Emilie; Carlson, Anders E.; Dutton, Andrea; Fischer, Hubertus; Goelzer, Heiko|info:eu-repo/dai/nl/412549123; Govin, Aline; Haywood, Alan; Joos, Fortunat; Legrande, Allegra N.; Lipscomb, William H.; Lohmann, Gerrit; Mahowald, Natalie; Nehrbass-Ahles, Christoph; Pausata, Francesco S. R.; Peterschmitt, Jean-yves; Phipps, Steven J.; Renssen, Hans; Zhang, Qiong

2017-01-01

Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last

The association between Modic changes and pain during 1-year follow-up in patients with lumbar radicular pain

International Nuclear Information System (INIS)

Schistad, Elina Iordanova; Roee, Cecilie; Espeland, Ansgar; Rygh, Lars Joergen; Gjerstad, Johannes

2014-01-01

To examine whether Modic changes influence pain during a 1-year follow-up in patients with lumbar radicular pain. A total of 243 patients with lumbar radicular pain due to disc herniation were recruited from two hospitals in Norway and followed up at 6 weeks, 6 months, and 12 months. On baseline lumbar magnetic resonance images, two observers independently evaluated Modic changes (types I-III; craniocaudal size 0-3). Outcomes were sensory pain (McGill Pain Questionnaire), back and leg pain (visual analogue scale, VAS). Association between Modic type and outcomes was explored with a mixed model and then by two-way analysis of variance (ANOVA) at each time point with Modic and treatment groups (surgical, n = 126; nonsurgical, n = 117) as fixed factors, adjusted for disc degeneration, age, sex, smoking, and duration of radicular pain. Modic size was also analyzed using ANOVA. Pain scores had decreased significantly at 1-year follow-up. Modic type was significantly related to McGill sensory scores (mixed model: p = 0.014-0.026; ANOVA: p = 0.007 at 6 weeks), but not to VAS back pain or VAS leg pain scores. At 6 weeks, the mean McGill sensory score was higher in Modic I than in Modic II-III patients (p = 0.003) and in patients without Modic changes (p = 0.018). Modic size L1-S1 was not associated with pain outcomes. Patients with lumbar radicular pain have a substantial pain reduction during 1-year follow-up, but Modic type I changes may imply a slower initial decrease in sensory pain. (orig.)

The association between Modic changes and pain during 1-year follow-up in patients with lumbar radicular pain

Energy Technology Data Exchange (ETDEWEB)

Schistad, Elina Iordanova; Roee, Cecilie [Oslo University Hospital, Department of Physical Medicine and Rehabilitation, Ullevaal, Nydalen, Postbox 4956, Oslo (Norway); University of Oslo, Faculty of Medicine, Oslo (Norway); Espeland, Ansgar [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Section for Radiology, Department of Clinical Medicine, Bergen (Norway); Rygh, Lars Joergen [Haukeland University Hospital, Department of Anesthesiology, Bergen (Norway); Gjerstad, Johannes [National Institute of Occupational Health, Oslo (Norway); University of Oslo, Department of Molecular Biosciences, Oslo (Norway)

2014-09-15

To examine whether Modic changes influence pain during a 1-year follow-up in patients with lumbar radicular pain. A total of 243 patients with lumbar radicular pain due to disc herniation were recruited from two hospitals in Norway and followed up at 6 weeks, 6 months, and 12 months. On baseline lumbar magnetic resonance images, two observers independently evaluated Modic changes (types I-III; craniocaudal size 0-3). Outcomes were sensory pain (McGill Pain Questionnaire), back and leg pain (visual analogue scale, VAS). Association between Modic type and outcomes was explored with a mixed model and then by two-way analysis of variance (ANOVA) at each time point with Modic and treatment groups (surgical, n = 126; nonsurgical, n = 117) as fixed factors, adjusted for disc degeneration, age, sex, smoking, and duration of radicular pain. Modic size was also analyzed using ANOVA. Pain scores had decreased significantly at 1-year follow-up. Modic type was significantly related to McGill sensory scores (mixed model: p = 0.014-0.026; ANOVA: p = 0.007 at 6 weeks), but not to VAS back pain or VAS leg pain scores. At 6 weeks, the mean McGill sensory score was higher in Modic I than in Modic II-III patients (p = 0.003) and in patients without Modic changes (p = 0.018). Modic size L1-S1 was not associated with pain outcomes. Patients with lumbar radicular pain have a substantial pain reduction during 1-year follow-up, but Modic type I changes may imply a slower initial decrease in sensory pain. (orig.)

Ancient geographical gaps and paleo-climate shape the phylogeography of an endemic bird in the sky islands of southern India.

Science.gov (United States)

Robin, V V; Sinha, Anindya; Ramakrishnan, Uma

2010-10-13

Sky islands, formed by the highest reaches of mountain tracts physically isolated from one another, represent one of the biodiversity-rich regions of the world. Comparative studies of geographically isolated populations on such islands can provide valuable insights into the biogeography and evolution of species on these islands. The Western Ghats mountains of southern India form a sky island system, where the relationship between the island structure and the evolution of its species remains virtually unknown despite a few population genetic studies. We investigated how ancient geographic gaps and glacial cycles have partitioned genetic variation in modern populations of a threatened endemic bird, the White-bellied Shortwing Brachypteryx major, across the montane Shola forests on these islands and also inferred its evolutionary history. We used bayesian and maximum likelihood-based phylogenetic and population-genetic analyses on data from three mitochondrial markers and one nuclear marker (totally 2594 bp) obtained from 33 White-bellied Shortwing individuals across five islands. Genetic differentiation between populations of the species correlated with the locations of deep valleys in the Western Ghats but not with geographical distance between these populations. All populations revealed demographic histories consistent with population founding and expansion during the Last Glacial Maximum. Given the level of genetic differentiation north and south of the Palghat Gap, we suggest that these populations be considered two different taxonomic species. Our results show that the physiography and paleo-climate of this region historically resulted in multiple glacial refugia that may have subsequently driven the evolutionary history and current population structure of this bird. The first avian genetic study from this biodiversity hotspot, our results provide insights into processes that may have impacted the speciation and evolution of the endemic fauna of this region.

Ancient geographical gaps and paleo-climate shape the phylogeography of an endemic bird in the sky islands of southern India.

Directory of Open Access Journals (Sweden)

V V Robin

2010-10-01

Full Text Available Sky islands, formed by the highest reaches of mountain tracts physically isolated from one another, represent one of the biodiversity-rich regions of the world. Comparative studies of geographically isolated populations on such islands can provide valuable insights into the biogeography and evolution of species on these islands. The Western Ghats mountains of southern India form a sky island system, where the relationship between the island structure and the evolution of its species remains virtually unknown despite a few population genetic studies.We investigated how ancient geographic gaps and glacial cycles have partitioned genetic variation in modern populations of a threatened endemic bird, the White-bellied Shortwing Brachypteryx major, across the montane Shola forests on these islands and also inferred its evolutionary history. We used bayesian and maximum likelihood-based phylogenetic and population-genetic analyses on data from three mitochondrial markers and one nuclear marker (totally 2594 bp obtained from 33 White-bellied Shortwing individuals across five islands. Genetic differentiation between populations of the species correlated with the locations of deep valleys in the Western Ghats but not with geographical distance between these populations. All populations revealed demographic histories consistent with population founding and expansion during the Last Glacial Maximum. Given the level of genetic differentiation north and south of the Palghat Gap, we suggest that these populations be considered two different taxonomic species.Our results show that the physiography and paleo-climate of this region historically resulted in multiple glacial refugia that may have subsequently driven the evolutionary history and current population structure of this bird. The first avian genetic study from this biodiversity hotspot, our results provide insights into processes that may have impacted the speciation and evolution of the endemic fauna of

How Hot was Africa during the Mid-Holocene? Reexamining Africa's Thermal History via integrated Climate and Proxy System Modeling

Science.gov (United States)

Dee, S.; Russell, J. M.; Morrill, C.

2017-12-01

Climate models predict Africa will warm by up to 5°C in the coming century. Reconstructions of African temperature since the Last Glacial Maximum (LGM) have made fundamental contributions to our understanding of past, present, and future climate and can help constrain predictions from general circulation models (GCMs). However, many of these reconstructions are based on proxies of lake temperature, so the confounding influences of lacustrine processes may complicate our interpretations of past changes in tropical climate. These proxy-specific uncertainties require robust methodology for data-model comparison. We develop a new proxy system model (PSM) for paleolimnology to facilitate data-model comparison and to fully characterize uncertainties in climate reconstructions. Output from GCMs are used to force the PSM to simulate lake temperature, hydrology, and associated proxy uncertainties. We compare reconstructed East African lake and air temperatures in individual records and in a stack of 9 lake records to those predicted by our PSM forced with Paleoclimate Model Intercomparison Project (PMIP3) simulations, focusing on the mid-Holocene (6 kyr BP). We additionally employ single-forcing transient climate simulations from TraCE (10 kyr to 4 kyr B.P. and historical), as well as 200-yr time slice simulations from CESM1.0 to run the lake PSM. We test the sensitivity of African climate change during the mid-Holocene to orbital, greenhouse gas, and ice-sheet forcing in single-forcing simulations, and investigate dynamical hypotheses for these changes. Reconstructions of tropical African temperature indicate 1-2ºC warming during the mid-Holocene relative to the present, similar to changes predicted in the coming decades. However, most climate models underestimate the warming observed in these paleoclimate data (Fig. 1, 6kyr B.P.). We investigate this discrepancy using the new lake PSM and climate model simulations, with attention to the (potentially non

The PMIP4 contribution to CMIP6 – Part 2: Two Interglacials, Scientific Objective and Experimental Design for Holocene and Last Interglacial Simulations

NARCIS (Netherlands)

Otto-Bliesner, B.; Braconnot, P.; Harrison, S.P.; Renssen, H.

2017-01-01

Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for Tier 1 simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last

Optical fiber communication systems with Matlab and Simulink models

CERN Document Server

Binh, Le Nguyen

2014-01-01

""This book adds an aspect of programming and simulation not so well developed in other books. It is complete in this sense and enables directly linking the physics of optical components and systems to realistic results.""-Martin Rochette, Associate Professor, McGill University, Quebec, Canada""…this will be an excellent textbook since it has all new development and information on optical communication systems…I think this book can easily replace many other textbooks in this field.""-Massoud Moussavi, California State Polytechnic University-Pomona""The book is well written. It describes the fu

Modelling hydrothermal venting in volcanic sedimentary basins: Impact on hydrocarbon maturation and paleoclimate

Science.gov (United States)

Iyer, Karthik; Schmid, Daniel W.; Planke, Sverre; Millett, John

2017-06-01

Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self-propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Vøring and Møre Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Vøring and Møre Basins alone and that a contribution

Reconstructing Climate Change: The Model-Data Ping-Pong

Science.gov (United States)

Stocker, T. F.

2017-12-01

When Cesare Emiliani, the father of paleoceanography, made the first attempts at a quantitative reconstruction of Pleistocene climate change in the early 1950s, climate models were not yet conceived. The understanding of paleoceanographic records was therefore limited, and scientists had to resort to plausibility arguments to interpret their data. With the advent of coupled climate models in the early 1970s, for the first time hypotheses about climate processes and climate change could be tested in a dynamically consistent framework. However, only a model hierarchy can cope with the long time scales and the multi-component physical-biogeochemical Earth System. There are many examples how climate models have inspired the interpretation of paleoclimate data on the one hand, and conversely, how data have questioned long-held concepts and models. In this lecture I critically revisit a few examples of this model-data ping-pong, such as the bipolar seesaw, the mid-Holocene greenhouse gas increase, millennial and rapid CO2 changes reconstructed from polar ice cores, and the interpretation of novel paleoceanographic tracers. These examples also highlight many of the still unsolved questions and provide guidance for future research. The combination of high-resolution paleoceanographic data and modeling has never been more relevant than today. It will be the key for an appropriate risk assessment of impacts on the Earth System that are already underway in the Anthropocene.

Plastic Surgery Inclusion in the Undergraduate Medical Curriculum: Perception, Challenges, and Career Choice—A Comparative Study

Directory of Open Access Journals (Sweden)

M. Farid

2017-01-01

Full Text Available Objective. The undergraduate medical curriculum has been overcrowded with core learning outcomes with no formal exposure to plastic surgery. The aim of this study was to compare medical students from two educational settings for the basic understanding, preferred learning method, and factors influencing a career choice in plastic surgery. Design and Setting. A prospective cohort study based on a web-based anonymous questionnaire sent to final year medical students at Birmingham University (United Kingdom, McGill University (Canada, and a control group (non-medical staff. The questions were about plastic surgery: (1 source of information and basic understanding; (2 undergraduate curriculum inclusion and preferred learning methods; (3 factors influencing a career choice. A similar questionnaire was sent to non-medical staff (control group. The data was analysed based on categorical outcomes (Chi-square χ2 and level of significance p≤0.05. Results. Questionnaire was analysed for 243 students (Birmingham, n=171/332, 52% (McGill n=72/132, 54%. Birmingham students (14% considered the word “plastic” synonymous with “cosmetic” more than McGill students (4%, p<0.025. Teaching was the main source of knowledge for McGill students (39%, p<0.001 while Birmingham students and control group chose the media (70%, p<0.001. McGill students (67% more than Birmingham (49%, p<0.010 considered curriculum inclusion. The preferred learning method was lectures for McGill students (61%, p<0.01 but an optional module for Birmingham (61%. A similar proportion (18% from both student groups considered a career in plastic surgery. Conclusions. Medical students recognised the need for plastic surgery inclusion in the undergraduate curriculum. There was a difference for plastic surgery source of information, operations, and preferred method of learning for students. The study highlighted the urgent need to reform plastic surgery undergraduate teaching in

TSPA Model for the Yucca Mountain Unsaturated Zone

International Nuclear Information System (INIS)

M.L. Wilson; C.K. Ho

2001-01-01

Yucca Mountain, Nevada, is being considered as a potential site for a repository for spent nuclear fuel and high-level radioactive waste. Total-system performance-assessment (TSPA) calculations are performed to evaluate the safety of the site. Such calculations require submodels for all important engineered and natural components of the disposal system. There are five submodels related to the unsaturated zone: climate, infiltration, mountain-scale flow of water, seepage into emplacement drifts, and radionuclide transport. For each of these areas, models have been developed and implemented for use in TSPA. The climate model is very simple (a set of climate states have been deduced from paleoclimate data, and the times when climate changes occur in the future have been estimated), but the other four models make use of complex process models involving time-consuming computer runs. An important goal is to evaluate the impact of uncertainties (e.g., incomplete knowledge of the site) on the estimates of potential repository performance, so particular attention is given to the key uncertainties for each area. Uncertainties in climate, infiltration, and mountain-scale flow are represented in TSPA simulations by means of discrete high, medium, and low cases, Uncertainties in seepage and radionuclide transport are represented by means of continuous probability distributions for several key parameters

A description of the FAMOUS (version XDBUA climate model and control run

Directory of Open Access Journals (Sweden)

A. Osprey

2008-12-01

Full Text Available FAMOUS is an ocean-atmosphere general circulation model of low resolution, capable of simulating approximately 120 years of model climate per wallclock day using current high performance computing facilities. It uses most of the same code as HadCM3, a widely used climate model of higher resolution and computational cost, and has been tuned to reproduce the same climate reasonably well. FAMOUS is useful for climate simulations where the computational cost makes the application of HadCM3 unfeasible, either because of the length of simulation or the size of the ensemble desired. We document a number of scientific and technical improvements to the original version of FAMOUS. These improvements include changes to the parameterisations of ozone and sea-ice which alleviate a significant cold bias from high northern latitudes and the upper troposphere, and the elimination of volume-averaged drifts in ocean tracers. A simple model of the marine carbon cycle has also been included. A particular goal of FAMOUS is to conduct millennial-scale paleoclimate simulations of Quaternary ice ages; to this end, a number of useful changes to the model infrastructure have been made.

Key features of the IPSL ocean atmosphere model and its sensitivity to atmospheric resolution

Energy Technology Data Exchange (ETDEWEB)

Marti, Olivier; Braconnot, P.; Bellier, J.; Brockmann, P.; Caubel, A.; Noblet, N. de; Friedlingstein, P.; Idelkadi, A.; Kageyama, M. [Unite Mixte CEA-CNRS-UVSQ, IPSL/LSCE, Gif-sur-Yvette Cedex (France); Dufresne, J.L.; Bony, S.; Codron, F.; Fairhead, L.; Grandpeix, J.Y.; Hourdin, F.; Musat, I. [Unite Mixte CNRS-Ecole Polytechnique-ENS-UPCM, IPSL/LMD, Paris Cedex 05 (France); Benshila, R.; Guilyardi, E.; Levy, C.; Madec, G.; Mignot, J.; Talandier, C. [unite mixte CNRS-IRD-UPMC, IPLS/LOCEAN, Paris Cedex 05 (France); Cadule, P.; Denvil, S.; Foujols, M.A. [Institut Pierre Simon Laplace des Sciences de l' Environnement (IPSL), Paris Cedex 05 (France); Fichefet, T.; Goosse, H. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Krinner, G. [Unite mixte CNRS-UJF Grenoble, LGGE, BP96, Saint-Martin-d' Heres (France); Swingedouw, D. [CNRS/CERFACS, Toulouse (France)

2010-01-15

This paper presents the major characteristics of the Institut Pierre Simon Laplace (IPSL) coupled ocean-atmosphere general circulation model. The model components and the coupling methodology are described, as well as the main characteristics of the climatology and interannual variability. The model results of the standard version used for IPCC climate projections, and for intercomparison projects like the Paleoclimate Modeling Intercomparison Project (PMIP 2) are compared to those with a higher resolution in the atmosphere. A focus on the North Atlantic and on the tropics is used to address the impact of the atmosphere resolution on processes and feedbacks. In the North Atlantic, the resolution change leads to an improved representation of the storm-tracks and the North Atlantic oscillation. The better representation of the wind structure increases the northward salt transports, the deep-water formation and the Atlantic meridional overturning circulation. In the tropics, the ocean-atmosphere dynamical coupling, or Bjerknes feedback, improves with the resolution. The amplitude of ENSO (El Nino-Southern oscillation) consequently increases, as the damping processes are left unchanged. (orig.)

40Ar/39Ar Geochronology of Supergene K-bearing Sulfate Minerals: Cenozoic Continental Weathering, Landscape Evolution and Paleoclimates in the Tu-Ha Basin, Northwestern China

Science.gov (United States)

Yang, J.; Zheng, D.; Chen, W.; Hough, B.; Qiu, H.; Wang, W.; Wu, Y.; Yang, L.

2017-12-01

40Ar/39Ar incremental-heating analyses of supergene jarosite and yavapaiite from three weathering profiles at the Hongshan, Liuhuangshan, and Caihuagou deposits in the Tu-Ha Basin, China, were carried out to provide numerical constraints on the timing and duration of weathering and derive insights into local paleoclimatic and landscape evolution. Well-constrained plateau ages and best-fitting inverse isochrons have been obtained for 11 samples, yield 40Ar/39Ar ages ranging from 33.3±0.5 Ma to 3.3±0.4 Ma (1σ). Our 40Ar/39Ar ages, combined with the published ages, indicate that the high elevations sites hosting the most complete and complex weathering profiles present. The presence of ancient weathering ages in current outcrop in the Tu-Ha Basin suggests that denudation was not homogeneous, and the landscape evolution follow a scarp retreat model. These geochronological results suggest that a protracted history of weathering and supergene enrichment and, by inference, arid-semiarid climate (with at least a moderate amount of precipitation (>10 cm/y)) favorable to intense chemical weathering emerged at 33.3 Ma, 27.7-23.3 Ma, and 16.4-14.7 Ma, and prevailed from 11-7.8 Ma. Then, a progressive change from arid-semiarid towards hyperarid conditions and predominantly hyperarid conditions may have persisted since at least ca. 3.3 Ma. The climatic implications inferred from the weathering geochronology are in agreement with the chemical parameters and isotopic compositions of the Cenozoic sedimentary sequence from the Lianmuqin section in the Tu-Ha Basin, attesting to the reliability of weathering geochronology by the 40Ar/39Ar method as an indicator of paleoclimate in arid areas. Our results suggest that the retreat of the Paratethys Sea, which would have reduced eastward water vapor transport by the westerlies to the Tu-Ha Basin, led to its aridification in the Oligocene and that increased rain shadow effects, resulting from uplift of the Tibetan Plateau and Tian Shan

Climatic history of the northeastern United States during the past 3000 years

Directory of Open Access Journals (Sweden)

J. R. Marlon

2017-10-01

Full Text Available Many ecosystem processes that influence Earth system feedbacks – vegetation growth, water and nutrient cycling, disturbance regimes – are strongly influenced by multidecadal- to millennial-scale climate variations that cannot be directly observed. Paleoclimate records provide information about these variations, forming the basis of our understanding and modeling of them. Fossil pollen records are abundant in the NE US, but cannot simultaneously provide information about paleoclimate and past vegetation in a modeling context because this leads to circular logic. If pollen data are used to constrain past vegetation changes, then the remaining paleoclimate archives in the northeastern US (NE US are quite limited. Nonetheless, a growing number of diverse reconstructions have been developed but have not yet been examined together. Here we conduct a systematic review, assessment, and comparison of paleotemperature and paleohydrological proxies from the NE US for the last 3000 years. Regional temperature reconstructions (primarily summer show a long-term cooling trend (1000 BCE–1700 CE consistent with hemispheric-scale reconstructions, while hydroclimate data show gradually wetter conditions through the present day. Multiple proxies suggest that a prolonged, widespread drought occurred between 550 and 750 CE. Dry conditions are also evident during the Medieval Climate Anomaly, which was warmer and drier than the Little Ice Age and drier than today. There is some evidence for an acceleration of the longer-term wetting trend in the NE US during the past century; coupled with an abrupt shift from decreasing to increasing temperatures in the past century, these changes could have wide-ranging implications for species distributions, ecosystem dynamics, and extreme weather events. More work is needed to gather paleoclimate data in the NE US to make inter-proxy comparisons and to improve estimates of uncertainty in reconstructions.

Carbon isotopes in the ocean model of the Community Earth System Model (CESM1

Directory of Open Access Journals (Sweden)

A. Jahn

2015-08-01

Full Text Available Carbon isotopes in the ocean are frequently used as paleoclimate proxies and as present-day geochemical ocean tracers. In order to allow a more direct comparison of climate model results with this large and currently underutilized data set, we added a carbon isotope module to the ocean model of the Community Earth System Model (CESM, containing the cycling of the stable isotope 13C and the radioactive isotope 14C. We implemented the 14C tracer in two ways: in the "abiotic" case, the 14C tracer is only subject to air–sea gas exchange, physical transport, and radioactive decay, while in the "biotic" version, the 14C additionally follows the 13C tracer through all biogeochemical and ecological processes. Thus, the abiotic 14C tracer can be run without the ecosystem module, requiring significantly fewer computational resources. The carbon isotope module calculates the carbon isotopic fractionation during gas exchange, photosynthesis, and calcium carbonate formation, while any subsequent biological process such as remineralization as well as any external inputs are assumed to occur without fractionation. Given the uncertainty associated with the biological fractionation during photosynthesis, we implemented and tested three parameterizations of different complexity. Compared to present-day observations, the model is able to simulate the oceanic 14C bomb uptake and the 13C Suess effect reasonably well compared to observations and other model studies. At the same time, the carbon isotopes reveal biases in the physical model, for example, too sluggish ventilation of the deep Pacific Ocean.

Carbon isotopes in the ocean model of the Community Earth System Model (CESM1)

Science.gov (United States)

Jahn, A.; Lindsay, K.; Giraud, X.; Gruber, N.; Otto-Bliesner, B. L.; Liu, Z.; Brady, E. C.

2015-08-01

Carbon isotopes in the ocean are frequently used as paleoclimate proxies and as present-day geochemical ocean tracers. In order to allow a more direct comparison of climate model results with this large and currently underutilized data set, we added a carbon isotope module to the ocean model of the Community Earth System Model (CESM), containing the cycling of the stable isotope 13C and the radioactive isotope 14C. We implemented the 14C tracer in two ways: in the "abiotic" case, the 14C tracer is only subject to air-sea gas exchange, physical transport, and radioactive decay, while in the "biotic" version, the 14C additionally follows the 13C tracer through all biogeochemical and ecological processes. Thus, the abiotic 14C tracer can be run without the ecosystem module, requiring significantly fewer computational resources. The carbon isotope module calculates the carbon isotopic fractionation during gas exchange, photosynthesis, and calcium carbonate formation, while any subsequent biological process such as remineralization as well as any external inputs are assumed to occur without fractionation. Given the uncertainty associated with the biological fractionation during photosynthesis, we implemented and tested three parameterizations of different complexity. Compared to present-day observations, the model is able to simulate the oceanic 14C bomb uptake and the 13C Suess effect reasonably well compared to observations and other model studies. At the same time, the carbon isotopes reveal biases in the physical model, for example, too sluggish ventilation of the deep Pacific Ocean.

Aragonite-Calcite Inversion During Biogenic Carbonate Sampling: Considerations for Interpreting Isotopic Measurements in Paleoclimate Studies

Science.gov (United States)

Waite, A. J.; Swart, P. K.

2011-12-01

, suggests that the isotopic depletion is tied to the polymorphic inversion of aragonite to calcite, and not just random chance based on natural isotopic variability in the skeleton. There appears to be no relationship between the percent inversion and carbon isotopic composition. Elemental ratios also appear to remain stable during the heating and inversion process. The findings of this and published studies present, in many cases, conflicting views of the isotopic fractionation associated with inversion of aragonite to calcite. Discrepancies such as this likely result from subtle differences in sampling protocol related to instruments, drill bits, skeletal density, and possibly even laboratory conditions like temperature and humidity, further complicating our understanding and interpretation of such observations. Preliminary investigation suggests that altering milling conditions or wet milling may reduce the extent of alteration. Unfortunately, milling/drilling remains one of the only practical methods of sampling biogenic carbonates at a high resolution for paleoclimate work and, as such, caution should be taken in the interpretation of oxygen isotopic measurements from specimens of this nature.

Application of heat pipe technology in permanent mold casting of nonferrous alloys

Science.gov (United States)

Elalem, Kaled

The issue of mold cooling is one, which presents a foundry with a dilemma. On the one hand; the use of air for cooling is safe and practical, however, it is not very effective and high cost. On the other hand, water-cooling can be very effective but it raises serious concerns about safety, especially with a metal such as magnesium. An alternative option that is being developed at McGill University uses heat pipe technology to carry out the cooling. The experimental program consisted of designing a permanent mold to produce AZ91E magnesium alloy and A356 aluminum alloy castings with shrinkage defects. Heat pipes were then used to reduce these defects. The heat pipes used in this work are novel and are patent pending. They are referred to as McGill Heat Pipes. Computer modeling was used extensively in designing the mold and the heat pipes. Final designs for the mold and the heat pipes were chosen based on the modeling results. Laboratory tests of the heat pipe were performed before conducting the actual experimental plan. The laboratory testing results verified the excellent performance of the heat pipes as anticipated by the model. An industrial mold made of H13 tool steel was constructed to cast nonferrous alloys. The heat pipes were installed and initial testing and actual industrial trials were conducted. This is the first time where a McGill heat pipe was used in an industrial permanent mold casting process for nonferrous alloys. The effects of cooling using heat pipes on AZ91E and A356 were evaluated using computer modeling and experimental trials. Microstructural analyses were conducted to measure the secondary dendrite arm spacing, SDAS, and the grain size to evaluate the cooling effects on the castings. The modeling and the experimental results agreed quite well. The metallurgical differences between AZ91E and A356 were investigated using modeling and experimental results. Selected results from modeling, laboratory and industrial trials are presented. The

Realistic Paleobathymetry of the Cenomanian–Turonian (94 Ma Boundary Global Ocean

Directory of Open Access Journals (Sweden)

Arghya Goswami

2018-01-01

Full Text Available At present, global paleoclimate simulations are prepared with bathtub-like, flat, featureless and steep walled ocean bathymetry, which is neither realistic nor suitable. In this article, we present the first enhanced version of a reconstructed paleobathymetry for Cenomanian–Turonian (94 Ma time in a 0.1° × 0.1° resolution, that is both realistic and suitable for use in paleo-climate studies. This reconstruction is an extrapolation of a parameterized modern ocean bathymetry that combines simple geophysical models (standard plate cooling model for the oceanic lithosphere based on ocean crustal age, global modern oceanic sediment thicknesses, and generalized shelf-slope-rise structures calibrated from a published global relief model of the modern world (ETOPO1 at active and passive continental margins. The base version of this Cenomanian–Turonian paleobathymetry reconstruction is then updated with known submarine large igneous provinces, plateaus, and seamounts to minimize the difference between the reconstructed paleobathymetry and the real bathymetry that once existed.

Changes in precipitation isotope-climate relationships from temporal grouping and aggregation of weekly-resolved USNIP data: impacts on paleoclimate and environmental applications

Science.gov (United States)

Akers, P. D.; Welker, J. M.

2015-12-01

Spatial variations in precipitation isotopes have been the focus of much recent research, but relatively less work has explored changes at various temporal scales. This is partly because most spatially-diverse and long-term isotope databases are offered at a monthly resolution, while daily or event-level records are spatially and temporally limited by cost and logistics. A subset of 25 United States Network for Isotopes in Precipitation (USNIP) sites with weekly-resolution in the east-central United States was analyzed for site-specific relationships between δ18O and δD (the local meteoric water line/LMWL), δ18O and surface temperature, and δ18O and precipitation amount. Weekly data were then aggregated into monthly and seasonal data to examine the effect of aggregation on correlation and slope values for each of the relationships. Generally, increasing aggregation improved correlations (>25% for some sites) due to a reduced effect of extreme values, but estimates on regression variable error increased (>100%) because of reduced sample sizes. Aggregation resulted in small, but significant drops (5-25%) in relationship slope values for some sites. Weekly data were also grouped by month and season to explore changes in relationships throughout the year. Significant subannual variability exists in slope values and correlations even for sites with very strong overall correlations. LMWL slopes are highest in winter and lowest in summer, while the δ18O-surface temperature relationship is strongest in spring. Despite these overall trends, a high level of month-to-month and season-to-season variability is the norm for these sites. Researchers blindly applying overall relationships drawn from monthly-resolved databases to paleoclimate or environmental research risk assuming these relationships apply at all temporal resolutions. When possible, researchers should match the temporal resolution used to calculate an isotopic relationship with the temporal resolution of

Prehistoric land use and Neolithisation in Europe in the context of regional climate events

Science.gov (United States)

Lemmen, C.; Wirtz, K. W.; Gronenborn, D.

2009-04-01

We present a simple, adaptation-driven, spatially explicit model of pre-Bronze age socio-technological change, called the Global Land Use and Technological Evolution Simulator (GLUES). The socio-technological realm is described by three characteristic traits: available technology, subsistence style ratio, and economic diversity. Human population and culture develop in the context of global paleoclimate and regional paleoclimate events. Global paleoclimate is derived from CLIMBER-2 Earth System Model anomalies superimposed on the IIASA temperature and precipitation database. Regional a forcing is provided by abrupt climate deteriorations from a compilation of 138 long-term high-resolution climate proxy time series from mostly terrestrial and near-shore archives. The GLUES simulator provides for a novel way to explore the interplay between climate, climate change, and cultural evolution both on the Holocene timescale as well as for short-term extreme event periods. We sucessfully simulate the migration of people and the diffusion of Neolithic technology from the Near East into Europe in the period 12000-4000 a BP. We find good agreement with recent archeological compilations of Western Eurasian Neolithic sites. No causal relationship between climate events and cultural evolution could be identified, but the speed of cultural development is found to be modulated by the frequency of climate events. From the demographic evolution and regional ressource consumption, we estimate regional land use change and prehistoric greenhouse gas emissions.

Using vegetation model-to-data comparisons to test the role of abiotic factors in the Neogene and Quaternary origins of modern C4 grasslands

Science.gov (United States)

Fox, D. L.; Strömberg, C.; Pau, S.; Taylor, L.; Lehmann, C.; Osborne, C.; Beerling, D. J.; Still, C. J.

2014-12-01

Grasslands dominated by taxa using the C4 photosynthetic pathway evolved on several continents during the Neogene and Quaternary, long after C4 photosynthesis first evolved among grasses. The histories of these ecosystems are relatively well documented in the geological record from stable carbon isotopes (fossil vertebrate herbivores, paleosols) and the plant microfossil record (pollen, phytoliths). The distinct biogeography and ecophysiology of modern C3 and C4 grasses have led to hypotheses explaining the origins of C4 grasslands in terms of long term changes in the Earth system such as increased aridity and decreasing atmospheric pCO2. However, proxies for key parameters of these hypotheses (e.g., temperature, precipitation, pCO2) are still in development, not yet widely applied, or remain contentious, so testing the hypotheses globally remains difficult. To understand better possible links between changes in the Earth system and the origin of C4 grasslands on different continents, we are undertaking a global scale comparison between observational records of C4 grass abundances in Miocene and Pliocene localities compiled from the literature, and three increasingly complex models of C4 dominance and abundance. The literature compilation comprises >2,600 δ13C values of both fossil vertebrates and of paleosol carbonates and >6,700 paleobotanical records. We are using paleoclimate output from the HadCM3L GCM over a range of pCO2 values for each epoch to model C4 dominance or abundance in grid cells as (Model 1) months per year exceeding the temperature at which net assimilation is greater for C4 than C3 photosynthesis (crossover temperature); (Model 2) the number of months per year exceeding the crossover temperature and having sufficient precipitation for growth (≥25 cm/yr; Collatz model); and (Model 3) the Sheffield Dynamic Global Vegetation Model (SDGVM), output from which includes biomass (g C/m2/yr) for distinct structural components (roots, stems, leaves

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures

NARCIS (Netherlands)

Douglas, P.M.J.; Affek, H.P.; Ivany, L.C.; Houben, A.J.P.; Sijp, W.P.; Sluijs, A.; Schouten, S.; Pagani, M.

2014-01-01

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at

Assessing the role of North Atlantic freshwater forcing in millennial scale climate variability: a tropical Atlantic perspective

Energy Technology Data Exchange (ETDEWEB)

Dahl, Kristina A [Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program, Woods Hole, MA (United States); Broccoli, Anthony J [Rutgers University, Department of Environmental Sciences, New Brunswick, NJ (United States); Stouffer, Ronald J [Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)

2005-03-01

This study analyzes a three-member ensemble of experiments, in which 0.1 Sv of freshwater was applied to the North Atlantic for 100 years in order to address the potential for large freshwater inputs in the North Atlantic to drive abrupt climate change. The model used is the GFDL R30 coupled ocean-atmosphere general circulation model. We focus in particular on the effects of this forcing on the tropical Atlantic region, which has been studied extensively by paleoclimatologists. In response to the freshwater forcing, North Atlantic meridional overturning circulation is reduced to roughly 40% by the end of the 100 year freshwater pulse. Consequently, the North Atlantic region cools by up to 8 C. The extreme cooling of the North Atlantic increases the pole-to-equator temperature gradient and requires more heat be provided to the high latitude Atlantic from the tropical Atlantic. To accommodate the increased heat requirement, the ITCZ shifts southward to allow for greater heat transport across the equator. Accompanying this southward ITCZ shift, the Northeast trade winds strengthen and precipitation patterns throughout the tropical Atlantic are altered. Specifically, precipitation in Northeast Brazil increases, and precipitation in Africa decreases slightly. In addition, we find that surface air temperatures warm over the tropical Atlantic and over Africa, but cool over northern South America. Sea-surface temperatures in the tropical Atlantic warm slightly with larger warm anomalies developing in the thermocline. These responses are robust for each member of the ensemble, and have now been identified by a number of freshwater forcing studies using coupled OAGCMs. The model responses to freshwater forcing are generally smaller in magnitude, but have the same direction, as paleoclimate data from the Younger Dryas suggest. In certain cases, however, the model responses and the paleoclimate data directly contradict one another. Discrepancies between the model simulations

Euthanasia and assisted suicide: a physician’s and ethicist’s perspectives

OpenAIRE

Boudreau, J. Donald; Somerville,Margaret

2014-01-01

J Donald Boudreau,1 Margaret A Somerville21Faculty of Medicine, Department of Medicine, McGill University, Montreal, QC, Canada; 2Faculty of Law, Faculty of Medicine, and Centre for Medicine, Ethics and Law, McGill University, Montreal, QC, CanadaAbstract: The debate on legalizing euthanasia and assisted suicide has a broad range of participants including physicians, scholars in ethics and health law, politicians, and the general public. It is conflictual, and despite its importance, particip...

Experimental and model-based analysis of differences in perception of cutaneous electrical stimulation across the sole of the foot.

Science.gov (United States)

Frahm, Ken Steffen; Mørch, Carsten Dahl; Grill, Warren M; Andersen, Ole Kæseler

2013-09-01

During electrocutaneous stimulations, variation in skin properties across locations can lead to differences in neural activation. However, little focus has been given to the effect of different skin thicknesses on neural activation. Electrical stimulation was applied to six sites across the sole of the foot. The intensities used were two and four times perception threshold. The subjects (n = 8) rated the perception quality and intensity using the McGill Pain Questionnaire and a visual analog scale (VAS). A finite element model was developed and combined with the activation function (AF) to estimate neural activation. Electrical stimulation was perceived as significantly less sharp at the heel compared to all other sites, except one site in the forefoot (logistic regression, p model showed that the AF was between 91 and 231 % higher at the five other sites than at the heel. The differences in perception across the sole of the foot indicated that the CNS received different inputs depending on the stimulus site. The lower AF at the heel indicated that the skin thicknesses could contribute to the perceived differences.

An automated approach for annual layer counting in ice cores

DEFF Research Database (Denmark)

Winstrup, Mai; Svensson, A. M.; Rasmussen, S. O.

2012-01-01

A novel method for automated annual layer counting in seasonally-resolved paleoclimate records has been developed. It relies on algorithms from the statistical framework of Hidden Markov Models (HMMs), which originally was developed for use in machine speech-recognition. The strength of the layer...

An automated approach for annual layer counting in ice cores

DEFF Research Database (Denmark)

Winstrup, Mai; Svensson, A. M.; Rasmussen, S. O.

2012-01-01

A novel method for automated annual layer counting in seasonally-resolved paleoclimate records has been developed. It relies on algorithms from the statistical framework of hidden Markov models (HMMs), which originally was developed for use in machine speech recognition. The strength of the layer...

Objective spatiotemporal proxy-model comparisons of the Asian monsoon for the last millennium

Science.gov (United States)

Anchukaitis, K. J.; Cook, E. R.; Ammann, C. M.; Buckley, B. M.; D'Arrigo, R. D.; Jacoby, G.; Wright, W. E.; Davi, N.; Li, J.

2008-12-01

The Asian monsoon system can be studied using a complementary proxy/simulation approach which evaluates climate models using estimates of past precipitation and temperature, and which subsequently applies the best understanding of the physics of the climate system as captured in general circulation models to evaluate the broad-scale dynamics behind regional paleoclimate reconstructions. Here, we use a millennial-length climate field reconstruction of monsoon season summer (JJA) drought, developed from tree- ring proxies, with coupled climate simulations from NCAR CSM1.4 and CCSM3 to evaluate the cause of large- scale persistent droughts over the last one thousand years. Direct comparisons are made between the external forced response within the climate model and the spatiotemporal field reconstruction. In order to identify patterns of drought associated with internal variability in the climate system, we use a model/proxy analog technique which objectively selects epochs in the model that most closely reproduce those observed in the reconstructions. The concomitant ocean-atmosphere dynamics are then interpreted in order to identify and understand the internal climate system forcing of low frequency monsoon variability. We examine specific periods of extensive or intensive regional drought in the 15th, 17th, and 18th centuries, many of which are coincident with major cultural changes in the region.

Sill intrusion driven fluid flow and vent formation in volcanic basins: Modeling rates of volatile release and paleoclimate effects

Science.gov (United States)

Iyer, Karthik; Schmid, Daniel

2016-04-01

Evidence of mass extinction events in conjunction with climate change occur throughout the geological record and may be accompanied by pronounced negative carbon isotope excursions. The processes that trigger such globally destructive changes are still under considerable debate. These include mechanisms such as poisoning from trace metals released during large volcanic eruptions (Vogt, 1972), CO2 released from lava degassing during the formation of Large Igneous Provinces (LIPs) (Courtillot and Renne, 2003) and CH4 release during the destabilization of sub-seafloor methane (Dickens et al., 1995), to name a few. Thermogenic methane derived from contact metamorphism associated with magma emplacement and cooling in sedimentary basins has been recently gaining considerable attention as a potential mechanism that may have triggered global climate events in the past (e.g. Svensen and Jamtveit, 2010). The discovery of hydrothermal vent complexes that are spatially associated with such basins also supports the discharge of greenhouse gases into the atmosphere (e.g. Jamtveit et al., 2004; Planke et al., 2005; Svensen et al., 2006). A previous study that investigated this process using a fluid flow model (Iyer et al., 2013) suggested that although hydrothermal plume formation resulting from sill emplacement may indeed release large quantities of methane at the surface, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales observed in the fossil record. Here, we reinvestigate the rates of gas release during sill emplacement in a case study from the Harstad Basin off-shore Norway with a special emphasis on vent formation. The presented study is based on a seismic line that crosses multiple sill structures emplaced around 55 Ma within the Lower Cretaceous sediments. A single well-defined vent complex is interpreted above the termination of the

Paleoclimate Records from New Zealand Maar Lakes, Insights into ENSO Teleconnections and Climatic Events in the South (West) Pacific.

Science.gov (United States)

Shulmeister, J.; Nobes, D. C.; Striewski, B.

2008-05-01

The maar craters of the New Zealand Auckland Volcanic Field (36.5°S, 174.5°E) contain some of the highest resolution late-Quaternary paleoclimate records in the Southern Hemisphere. Here we integrate laminae count results from recent drilling in the Hopua Crater with existing records from the nearby Onepoto Crater (Pepper et al., 2004). In total these records cover many thousands of years between the onset of the last glaciation maximum and the early mid-Holocene. The cores are strongly laminated. Individual laminae in both craters are very fine (sub-mm to mm scale) and form couplets which comprise a darker mineralogenic rich layer and a lighter diatomaceous layer. In places these couplets are annual, and may reflect seasonal algal blooms, but in other sections of the record, notably through the late-Glacial and Holocene, the couplets are deposited at inter-annual time scales. Spectral analyses of couplet thickness counts using a fast Fourier transform (FFT) with 64 to 256-year running windows, and a 50 per cent overlap indicate strong spectral power during the LGM and markedly weaker power during both the deglaciation and early Holocene. In fact there is no spectral strength for most of these periods. Three brief (centennial duration) events punctuate this extended period of low spectral power. These occur at c. 16 ka, c. 14.8 ka and during the early Holocene. They display spectral power in the 5-7yr ENSO window and also at longer time intervals that may be consistent with the Pacific Decadal Oscillation. We infer the local switching on (or up) of ENSO and PDO teleconnections and suspect these are embedded in circum-polar circulation changes. In addition to these spectral power episodes, there is a general increase in the number of couplet cycles per century between the deglaciation and the early mid-Holocene. This matches observations from Equador and Peru and suggests that trans-Pacific ENSO responses are in phase between western tropical South America and New

Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125-97 ka): insights from a Belgian speleothem

Science.gov (United States)

Vansteenberge, Stef; Verheyden, Sophie; Cheng, Hai; Edwards, R. Lawrence; Keppens, Eddy; Claeys, Philippe

2016-07-01

The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and ˜ 97 ka, with interruptions of growth occurring at 117.3-112.9 and 106.6-103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e-5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite

Flexible climate modeling systems: Lessons from Snowball Earth, Titan and Mars

Science.gov (United States)

Pierrehumbert, R. T.

2007-12-01

Climate models are only useful to the extent that real understanding can be extracted from them. Most leading- edge problems in climate change, paleoclimate and planetary climate require a high degree of flexibility in terms of incorporating model physics -- for example in allowing methane or CO2 to be a condensible substance instead of water vapor. This puts a premium on model design that allows easy modification, and on physical parameterizations that are close to fundamentals with as little empirical ad-hoc formulation as possible. I will provide examples from two approaches to this problem we have been using at the University of Chicago. The first is the FOAM general circulation model, which is a clean single-executable Fortran-77/c code supported by auxiliary applications in Python and Java. The second is a new approach based on using Python as a shell for assembling building blocks in compiled-code into full models. Applications to Snowball Earth, Titan and Mars, as well as pedagogical uses, will be discussed. One painful lesson we have learned is that Fortran-95 is a major impediment to portability and cross-language interoperability; in this light the trend toward Fortran-95 in major modelling groups is seen as a significant step backwards. In this talk, I will focus on modeling projects employing a full representation of atmospheric fluid dynamics, rather than "intermediate complexity" models in which the associated transports are parameterized.

Paleo-dust insights onto dust-climate interactions

Science.gov (United States)

Albani, S.; Mahowald, N. M.

2017-12-01

Mineral dust emissions are affected by changing climate conditions, and in turn dust impacts the atmospheric radiation budget, clouds and biogeochemical cycles. Climate and public health dust-related issues call for attention on the fate of the dust cycle in the future, and the representation of the dust cycle is now part of the strategy of the Paleoclimate Modelling Intercomparison Project phase 4 and the Coupled Model Intercomparison Project phase 6 (PMIP4-CMIP6). Since mineral aerosols are one of the most important natural aerosols, understanding past dust responses to climate in the paleoclimate will allow us to better understand mineral aerosol feedbacks with climate and biogeochemistry in the Anthropocene. Modern observations and paleoclimate records offer the possibility of multiple, complementary views on the global dust cycle, and allow to validate and/or constrain the numerical representation of dust in climate and Earth system models. We present our results from a set of simulations with the Community Earth System Model for different climate states, including present and past climates such as the pre-industrial, the mid-Holocene and the Last Glacial Maximum. A set of simulations including a prognostic dust cycle was thoroughly compared with a wide set of present day observations from different platforms and regions, in order to realistically constrain the magnitude of dust load, surface concentration, deposition, optical properties, and particle size distributions. The magnitude of emissions for past climate regimes was constrained based on compilations of paleodust mass accumulation rates and size distributions, as well as based on information on dust provenance. The comparison with a parallel set of simulations without dust allows estimating the impacts of dust on surface climate. We analyze impacts of dust on the mean and variability of surface temperature and precipitation in each climate state, as well as the impacts that changing dust emissions had

Pollen-Based Inverse Modelling versus Data Assimilation, two Different Ways to Consider Priors in Paleoclimate Reconstruction: Application to the Mediterranean Holocene

Science.gov (United States)

Guiot, J.

2017-12-01

In the last decades, climate reconstruction has much evolved. A important step has been passed with inverse modelling approach proposed by Guiot et al (2000). It is based on appropriate algorithms in the frame of the Bayesian statistical theory to estimate the inputs of a vegetation model when the outputs are known. The inputs are the climate variables that we want to reconstruct and the outputs are vegetation characteristics, which can be compared to pollen data. The Bayesian framework consists in defining prior distribution of the wanted climate variables and in using data and a model to estimate posterior probability distribution. The main interest of the method is the possibility to set different values of exogenous variables as the atmospheric CO2 concentration. The fact that the CO2 concentration has an influence on the photosynthesis and that its level is different between the calibration period (the 20th century) and the past, there is an important risk of biases on the reconstructions. After that initial paper, numerous papers have been published showing the interested of the method. In that approach, the prior distribution is fixed by educated guess of by using complementary information on the expected climate (other proxies or other records). In the data assimilation approach, the prior distribution is provided by a climate model. The use of a vegetation model together with proxy data, enable to calculate posterior distributions. Data assimilation consists in constraining climate model to reproduce estimates relatively close to the data, taking into account the respective errors of the data and of the climate model (Dubinkina et al, 2011). We compare both approaches using pollen data for the Holocene from the Mediterranean. Pollen data have been extracted from the European Pollen Database. The earth system model, LOVECLIM, is run to simulate Holocene climate with appropriate boundary conditions and realistic forcing. Simulated climate variables

Modeling the economic outcomes of immuno-oncology drugs: alternative model frameworks to capture clinical outcomes

Directory of Open Access Journals (Sweden)

Gibson EJ

2018-03-01

Full Text Available EJ Gibson,1 N Begum,1 I Koblbauer,1 G Dranitsaris,2 D Liew,3 P McEwan,4 AA Tahami Monfared,5,6 Y Yuan,7 A Juarez-Garcia,7 D Tyas,8 M Lees9 1Wickenstones Ltd, Didcot, UK; 2Augmentium Pharma Consulting Inc, Toronto, ON, Canada; 3Department of Epidemiology and Preventive Medicine, Alfred Hospital, Monash University, Melbourne, VIC, Australia; 4Health Economics and Outcomes Research Ltd, Cardiff, UK; 5Bristol-Myers Squibb Canada, Saint-Laurent, QC Canada; 6Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC, Canada; 7Bristol-Myers Squibb, Princeton, NJ, USA; 8Bristol-Myers Squibb, Uxbridge, UK; 9Bristol-Myers Squibb, Rueil-Malmaison, France Background: Economic models in oncology are commonly based on the three-state partitioned survival model (PSM distinguishing between progression-free and progressive states. However, the heterogeneity of responses observed in immuno-oncology (I-O suggests that new approaches may be appropriate to reflect disease dynamics meaningfully. Materials and methods: This study explored the impact of incorporating immune-specific health states into economic models of I-O therapy. Two variants of the PSM and a Markov model were populated with data from one clinical trial in metastatic melanoma patients. Short-term modeled outcomes were benchmarked to the clinical trial data and a lifetime model horizon provided estimates of life years and quality adjusted life years (QALYs. Results: The PSM-based models produced short-term outcomes closely matching the trial outcomes. Adding health states generated increased QALYs while providing a more granular representation of outcomes for decision making. The Markov model gave the greatest level of detail on outcomes but gave short-term results which diverged from those of the trial (overstating year 1 progression-free survival by around 60%. Conclusion: Increased sophistication in the representation of disease dynamics in economic models

Do Coupled Climate Models Correctly SImulate the Upward Branch of the Deept Ocean Global Conveyor?

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, Jorge L; Downes, Stephanie; Bianchi, Daniele

2013-01-17

The large-scale meridional overturning circulation (MOC) connects the deep ocean, a major reservoir of carbon, to the other components of the climate system and must therefore be accurately represented in Earth System Models. Our project aims to address the specific question of the pathways and mechanisms controlling the upwelling branch of the MOC, a subject of significant disagreement between models and observational syntheses, and among general circulation models. Observations of these pathways are limited, particularly in regions of complex hydrography such as the Southern Ocean. As such, we rely on models to examine theories of the overturning circulation, both physically and biogeochemically. This grant focused on a particular aspect of the meridional overturning circulation (MOC) where there is currently significant disagreement between models and observationally based analyses of the MOC, and amongst general circulation models. In particular, the research focused on addressing the following questions: 1. Where does the deep water that sinks in the polar regions rise to the surface? 2. What processes are responsible for this rise? 3. Do state-of-the-art coupled GCMs capture these processes? Our research had three key components: observational synthesis, model development and model analysis. In this final report we outline the key results from these areas of research for the 2007 to 2012 grant period. The research described here was carried out primarily by graduate student, Daniele Bianchi (now a Postdoc at McGill University, Canada), and Postdoc Stephanie Downes (now a Research Fellow at The Australian national University, Australia). Additional support was provided for programmers Jennifer Simeon as well as Rick Slater.

The PMIP4 contribution to CMIP6-Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments

NARCIS (Netherlands)

Kageyama, Masa; Albani, Samuel; Braconnot, Pascale; Harrison, Sandy P.; Hopcroft, Peter O.; Ivanovic, Ruza F.; Lambert, Fabrice; Marti, Olivier; Richard Peltier, W.; Peterschmitt, Jean Yves; Roche, Didier M.; Tarasov, Lev; Zhang, Xu; Brady, Esther C.; Haywood, Alan M.; Legrande, Allegra N.; Lunt, Daniel J.; Mahowald, Natalie M.; Mikolajewicz, Uwe; Nisancioglu, Kerim H.; Otto-Bliesner, Bette L.; Renssen, Hans; Tomas, Robert A.; Zhang, Qiong; Abe-Ouchi, Ayako; Bartlein, Patrick J.; Cao, Jian; Li, Qiang; Lohmann, Gerrit; Ohgaito, Rumi; Shi, Xiaoxu; Volodin, Evgeny; Yoshida, Kohei; Zhang, Xiao; Zheng, Weipeng

2017-01-01

The Last Glacial Maximum (LGM, 21 000 years ago) is one of the suite of paleoclimate simulations included in the current phase of the Coupled Model Intercomparison Project (CMIP6). It is an interval when insolation was similar to the present, but global ice volume was at a maximum, eustatic sea

Geophysical imaging of the lacustrine sediments deposited in the La Calderilla Volcanic Caldera (Gran Canaria Island, Spain) for paleoclimate research

Science.gov (United States)

Himi, Mahjoub; Rodríguez-González, Alejandro; Criado, Constantino; Tapias, Josefina C.; Ravazzi, Cesare; Pérez-Torrado, Francisco; Casas, Albert

2016-04-01

The discovery of well-preserved maar structures is important not only for studying the eruptive activity and formation of volcanoes, but also for paleoclimate research, since laminated maar lake sediments may contain very detailed archives of climate and environmental history. Maars are a singular type of volcanic structure generated by explosive phreatomagmatic eruptions as a result of interaction between rising magma and groundwater. This kind of structures are characterised by circular craters, often filled with water and/or lacustrine sediments and surrounded by a ring of pyroclastic deposits.Recently a borehole was drilled at the bottom of La Calderilla volcanic complex which penetrated about 8.7 m in its sedimentary sequence and paleobotanical study has supplied the first evidence of paleoenvironmental evolution during the Holocene on the Gran Canaria Island. This survey, however, did not penetrate into the substrate because the total thickness of the sedimentary fill was unknown. Since the age of formation of La Calderilla volcanic complex based on K/Ar dating is about 85,000 years (Upper Pleistocene), the possibility of its sedimentary fill extends beyond of the Holocene is extremely attractive, since, for example, there are few paleoenvironmental data regarding how much the last glaciation that affected the Canary Islands. In these circumstances, the knowledge of the total thickness of the lacustrine sediments is crucial to design a deeper borehole in the next future. Therefore, the subsurface characterisation provided by geophysics is essential for determining thickness and geometry of the sedimentary filling. Multielectrode ERT method was used to obtain five 2-D resistivity cross-sections into La Calderilla volcanic caldera. An Iris Syscal Pro resistivity system with 48 electrodes connected to a 94 m long cable (2m electrode spacing) in Wenner-Schlumberger configuration for an investigation depth of about 20 m. Data quality (q Current injected was

Reconstructing a lost Eocene Paradise, Part II: On the utility of dynamic global vegetation models in pre-Quaternary climate studies

Science.gov (United States)

Shellito, Cindy J.; Sloan, Lisa C.

2006-02-01

Models that allow vegetation to respond to and interact with climate provide a unique method for addressing questions regarding feedbacks between the ecosystem and climate in pre-Quaternary time periods. In this paper, we consider how Dynamic Global Vegetation Models (DGVMs), which have been developed for simulations with present day climate, can be used for paleoclimate studies. We begin with a series of tests in the NCAR Land Surface Model (LSM)-DGVM with Eocene geography to examine (1) the effect of removing C 4 grasses from the available plant functional types in the model; (2) model sensitivity to a change in soil texture; and (3), model sensitivity to a change in the value of pCO 2 used in the photosynthetic rate equations. The tests were designed to highlight some of the challenges of using these models and prompt discussion of possible improvements. We discuss how lack of detail in model boundary conditions, uncertainties in the application of modern plant functional types to paleo-flora simulations, and inaccuracies in the model climatology used to drive the DGVM can affect interpretation of model results. However, we also review a number of DGVM features that can facilitate understanding of past climates and offer suggestions for improving paleo-DGVM studies.

Quantitative Hydraulic Models Of Early Land Plants Provide Insight Into Middle Paleozoic Terrestrial Paleoenvironmental Conditions

Science.gov (United States)

Wilson, J. P.; Fischer, W. W.

2010-12-01

humidity (25°C) could cause sufficient cavitation to reduce hydraulic conductivity by 50%. This suggests that the Early Devonian environments that supported the earliest vascular plants were not subject to prolonged midseason droughts, or, alternatively, that the growing season was short. This places minimum constraints on water availability (e.g., groundwater hydration, relative humidity) in locations where Asteroxylon fossils are found; these environments must have had high relative humidities, comparable to tropical riparian environments. Given these constraints, biome-scale paleovegetation models that place early vascular plants distal to water sources can be revised to account for reduced drought tolerance. Paleoclimate proxies that treat early terrestrial plants as functionally interchangeable can incorporate physiological differences in a quantitatively meaningful way. Application of hydraulic models to fossil plants provides an additional perspective on the 475 million-year history of terrestrial photosynthetic environments and has potential to corroborate other plant-based paleoclimate proxies.

Impact of practice leadership management style on staff experience in services for people with intellectual disability and challenging behaviour: A further examination and partial replication.

Science.gov (United States)

Deveau, Roy; McGill, Peter

2016-09-01

Practice leadership (PL) style of frontline management has been shown to be associated with better experiences for staff working with people who may exhibit challenging behaviours (Deveau & McGill, 2014). This study aimed to examine additional staff experience factors with a different, larger sample and to partially replicate the findings of (Deveau & McGill, 2014). This study was a survey of staff self-reported data collected as part of a larger study. Information was collected on PL and staff experiences of: stress, turnover, job satisfaction and positive work experiences. The results broadly supported Deveau and McGill (2014) and demonstrated an association between PL and greater job satisfaction and positive experiences for staff. Results on staff turnover were inconsistent. The positive impact of PL on staff experience was further supported by this study. Suggestions are made for further research. These findings suggest further research is needed to examine the potential of interventions in frontline management/leadership practice to improve staff experience of working in challenging environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sources of Holocene variability of oxygen isotopes in paleoclimate archives

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A. N. LeGrande

2009-08-01

Full Text Available Variability in water isotopes has been captured in numerous archives and used to infer past climate changes. Here we examine water isotope variability over the course of the Holocene using the water-isotope enabled, coupled atmosphere-ocean general circulation model, GISS ModelE-R. Eight Holocene time slices, ~1000 years apart are simulated and driven by estimated changes in orbital configuration, greenhouse gases, and ice sheet extent. We find that simulated water isotope archives match well with those seen in ice cores, ocean sediment cores, and speleothems. The climate changes associated with the water isotope changes, however, are more complex than simple modern spatial slope interpretations might suggest. In particular, water isotope variability in Asian speleothems is linked to alterations in landward water vapor transport, not local precipitation, and ice sheet changes over North America lead to the masking of temperature signals in Summit, Greenland. Salinity-seawater isotope variability is complicated by inter-ocean basin exchanges of water vapor. Water isotopes do reflect variability in the hydrology, but are better interpreted in terms of regional hydrological cycle changes rather than as indicators of local climate.

Jet and electromagnetic tomography (JET) of extreme phases of matter in heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Heinz, Ulrich [The Ohio State Univ., Columbus, OH (United States)

2015-08-31

The Ohio State University (OSU) group contributed to the deliverables of the JET Collaboration three major products: 1. The code package iEBE-VISHNU for modeling the dynamical evolution of the soft medium created in relativistic heavy-ion collisions, from its creation all the way to final freeze-out using a hybrid approach that interfaces a free-streaming partonic pre-equilbrium stage with a (2+1)-dimensional viscous relativistic fluid dynamical stage for the quark-gluon plasma (QGP) phase and the microscopic hadron cascade UrQMD for the hadronic rescattering and freeze-out stage. Except for UrQMD, all dynamical evolution components and interfaces were developed at OSU and tested and implemented in collaboration with the Duke University group. 2. An electromagnetic radiation module for the calculation of thermal photon emission from the QGP and hadron resonance gas stages of a heavy-ion collision, with emission rates that have been corrected for viscous effects in the expanding medium consistent with the bulk evolution. The electromagnetic radiation module was developed under OSU leadership in collaboration with the McGill group and has been integrated in the iEBE-VISHNU code package. 3. An interface between the Monte Carlo jet shower evolution and hadronization codes developed by the Wayne State University (WSU), McGill and Texas A&M groups and the iEBE-VISHNU bulk evolution code, for performing jet quenching and jet shape modification studies in a realistically modeled evolving medium that was tuned to measured soft hadron data. Building on work performed at OSU for the theoretical framework used to describe the interaction of jets with the medium, initial work on the jet shower Monte Carlo was started at OSU and moved to WSU when OSU Visiting Assistant Professor Abhijit Majumder accepted a tenure track faculty position at WSU in September 2011. The jet-hydro interface was developed at OSU and WSU and tested and implemented in collaboration with the McGill, Texas

Evaluation of long-term geological and climatic changes in the Spanish programme

International Nuclear Information System (INIS)

Torres, T.; Ortiz, J.E.; Cortes, A.; Delgado, A.

2004-01-01

The Bio-molecular Stratigraphy Laboratory of the Madrid School of Mines has been largely involved in the analysis of long-term paleo-environmental changes in the Iberian Peninsula during the Quaternary. Some of the research projects were UE funded: Paleo-climatological Revision of Climate Evolution in Western Mediterranean Region. Evaluation of Altered Scenarios, Evidence from Quaternary Infill Paleo-hydrogeology, Sequential Biosphere modelling function of Climate evolution models; Paleo-hydrogeological Data Analysis and Model Testing. Other projects were funded by the National Company for Radioactive Waste Management (ENRESA) and the Spanish Nuclear Safety Council (CSN): 'Paleo-climate reconstruction from Middle Pleistocene times through dating and isotopic analysis of tufa deposits'; 'Paleo-environmental evolution of the southern part of the Iberian Peninsula'; 'Paleo-climate'. On a minor scale the laboratory was also involved in the study of some argillaceous media: 'Organic Geochemistry of some deep Spanish argillaceous formations' and 'Effects of climatic change on the argillaceous series of the Duero and Ebro basins'. Here we will present some of the results obtained from tufa deposits analysis and paleo-environmental information from the Guadix-Baza Basin composite-stratigraphical-type-section study. (authors)

Fire, ice, water, and dirt: A simple climate model

Science.gov (United States)

Kroll, John

2017-07-01

A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

Fire, ice, water, and dirt: A simple climate model.

Science.gov (United States)

Kroll, John

2017-07-01

A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

Isotope tracers in global water and climate studies of the past and present

International Nuclear Information System (INIS)

Edwards, T.W.D.; Birks, S.J.; Gibson, J.J.

2002-01-01

To date the global distribution of isotopes in modern precipitation has been characterized almost exclusively from the IAEA/WMO GNIP database, although patchiness of GNIP station records in both time and space has limited the potential of isotope hydrology and climate applications in some areas. Herein, we discuss the prospect of utilizing GCMs for simulating global isotope distributions as a supplementary tool for modern and paleoclimate isotope studies to bridge this gap. Such models currently generate reliable zonal isotope fields, and it is anticipated that future enhancements in finescale resolution of GCMs, and incorporation of land-surface feedbacks and topography will allow for future development of a global reanalysis data set ground-truthed by GNIP. Compilation of time-slice maps of past isotope distribution in precipitation from archival records of meteoric waters also offers significant potential to ground-truth paleoclimate simulations extending back tens to hundreds of thousands of years. (author)

Using of microvertebrate remains in reconstruction of late quaternary (Holocene paleoclimate, Eastern Iran

Directory of Open Access Journals (Sweden)

Mansour Aliabadian

2015-09-01

Full Text Available   Introduction   Study of quaternary microvertebrate remains in eastern Iran, according to a few of the sediments is very important. Reconstruction of quaternary climate in many parts of West and North West of Iran as the biggest karst state is possible, such as cave Kani Mikaiel (Hashemi et al. 2005, 2006, 2007ab, 2008 2010, Jangjoo et al . 2010, Yafteh cave (Otte et al. 2007, Hashemi et al. 2015. However, such studies were very poor in eastern and north-eastern Iran (Hashemi and darvish 2006 Hashemi et al. 2008, 2015. Investigation of taxonomic identification quantification and distribution of micromammals revealed that these remains are useful in paleontology and archaeological research, because their abundance is useful for paleobiostratigraphy and dating of continental sediments. The recent research is about reconstruction of paleoclimate in two archeological sites of Konar sandal (KS (Jiroft and Tapeh Naderi (TN (Mashhad based on the microvertebrate and especially Tatera indica species. In these sites we attempted to solve the palaeoenvironment condition by analysis of rodent remains which hold the greatest potential to monitoring of ecological parameters (Hoover et al. 1977 Getz 1961 Reig 1970 Merritt 1974. Combining of a rich network of data with using of morphological and morphometric methods reconstruction of paleoenvironment documentation and investigation of their relationship with the environment is the main result of this research .       Material & Methods   In both zooarchaeological samples which are composed of juveniles and young individual rodent, (KS, NISP=800 and TN, NISP=3 cranial and postcranial remains were sorted anatomically and washed with water. Dental pattern of mandible and maxillary tooth rows were drowns using a drawing tube connecting to a stereomicroscope (Olympus SZH-10. All recovered teeth fragments were measured based on the greatest dental length and width of the upper and lower jaw molars

Using of microvertebrate remains in reconstruction of late quaternary (Holocene paleoclimate, Eastern Iran

Directory of Open Access Journals (Sweden)

Narges Hashemi

2015-10-01

Full Text Available Introduction   Study of quaternary microvertebrate remains in eastern Iran, according to a few of the sediments is very important. Reconstruction of quaternary climate in many parts of West and North West of Iran as the biggest karst state is possible, such as cave Kani Mikaiel (Hashemi et al. 2005, 2006, 2007a;b, 2008; 2010, Jangjoo et al . 2010, Yafteh cave (Otte et al. 2007, Hashemi et al. 2015. However, such studies were very poor in eastern and north-eastern Iran (Hashemi and darvish 2006; Hashemi et al. 2008, 2015. Investigation of taxonomic identification; quantification and distribution of micromammals revealed that these remains are useful in paleontology and archaeological research, because their abundance is useful for paleobiostratigraphy and dating of continental sediments. The recent research is about reconstruction of paleoclimate in two archeological sites of Konar sandal (KS (Jiroft and Tapeh Naderi (TN (Mashhad based on the microvertebrate and especially Tatera indica species. In these sites we attempted to solve the palaeoenvironment condition by analysis of rodent remains which hold the greatest potential to monitoring of ecological parameters (Hoover et al. 1977; Getz 1961; Reig 1970; Merritt 1974. Combining of a rich network of data with using of morphological and morphometric methods; reconstruction of paleoenvironment; documentation and investigation of their relationship with the environment is the main result of this research .       Material & Methods   In both zooarchaeological samples which are composed of juveniles and young individual rodent, (KS, NISP=800 and TN, NISP=3 cranial and postcranial remains were sorted anatomically and washed with water. Dental pattern of mandible and maxillary tooth rows were drowns using a drawing tube connecting to a stereomicroscope (Olympus SZH-10. All recovered teeth fragments were measured based on the greatest dental length and width of the upper and lower jaw molars when

The use of metformin is associated with decreased lumbar radiculopathy pain [Erratum

Directory of Open Access Journals (Sweden)

Taylor A

2014-02-01

Full Text Available Taylor A, Westveld AH, Szkudlinska M, et al. J Pain Res. 2013;6:755–763. The notes section for Table 2 should read:Notes: Sections 1 and 2 are adapted from the short-form McGill pain questionnaire.19 Patients were asked to identify their pain with the provided scale. Melzack R. The short-form McGill Pain Questionnaire. Pain. 1987;30(2:191–197. The figure has been reproduced with permission of the International Association for the Study of Pain® (IASP. The figure may not be reproduced for any other purpose without permission.Read the original article

Proceedings of the national symposium on current trends in geochemistry, exploration and environment: abstract book

International Nuclear Information System (INIS)

2015-01-01

The topics covered in this symposium are solid earth geochemistry and geochemical modeling, precambrian geology, geochemistry and petrogenesis, geochemistry, peterogenisis, sedimentology, chemostratigraphy and paleoclimate, atomic minerals, ferrous/non ferrous minerals, REE minerals, PGE and base metals, oil, hydrocarbons, industrial minerals and gem stones, hydrogeochemistry, environmental geochemistry, biogeochemistry and medical geology and analytical geochemistry and method development. Papers relevant to INIS are indexed separately

Global Climate Models for the Classroom: The Educational Impact of Student Work with a Key Tool of Climate Scientists

Science.gov (United States)

Bush, D. F.; Sieber, R.; Seiler, G.; Chandler, M. A.; Chmura, G. L.

2017-12-01

Efforts to address climate change require public understanding of Earth and climate science. To meet this need, educators require instructional approaches and scientific technologies that overcome cultural barriers to impart conceptual understanding of the work of climate scientists. We compared student inquiry learning with now ubiquitous climate education toy models, data and tools against that which took place using a computational global climate model (GCM) from the National Aeronautics and Space Administration (NASA). Our study at McGill University and John Abbott College in Montreal, QC sheds light on how best to teach the research processes important to Earth and climate scientists studying atmospheric and Earth system processes but ill-understood by those outside the scientific community. We followed a pre/post, control/treatment experimental design that enabled detailed analysis and statistically significant results. Our research found more students succeed at understanding climate change when exposed to actual climate research processes and instruments. Inquiry-based education with a GCM resulted in significantly higher scores pre to post on diagnostic exams (quantitatively) and more complete conceptual understandings (qualitatively). We recognize the difficulty in planning and teaching inquiry with complex technology and we also found evidence that lectures support learning geared toward assessment exams.

Orbital Noise in the Earth System and Climate Fluctuations

Science.gov (United States)

Liu, Han-Shou; Smith, David E. (Technical Monitor)

2001-01-01

Frequency noise in the variations of the Earth's obliquity (tilt) can modulate the insolation signal for climate change. Including this frequency noise effect on the incoming solar radiation, we have applied an energy balance climate model to calculate the climate fluctuations for the past one million years. Model simulation results are in good agreement with the geologically observed paleoclimate data. We conclude that orbital noise in the Earth system may be the major cause of the climate fluctuation cycles.

Towards a semantic web of paleoclimatology

Science.gov (United States)

Emile-Geay, J.; Eshleman, J. A.

2012-12-01

The paleoclimate record is information-rich, yet signifiant technical barriers currently exist before it can be used to automatically answer scientific questions. Here we make the case for a universal format to structure paleoclimate data. A simple example demonstrates the scientific utility of such a self-contained way of organizing coral data and meta-data in the Matlab language. This example is generalized to a universal ontology that may form the backbone of an open-source, open-access and crowd-sourced paleoclimate database. Its key attributes are: 1. Parsability: the format is self-contained (hence machine-readable), and would therefore enable a semantic web of paleoclimate information. 2. Universality: the format is platform-independent (readable on all computer and operating systems), and language- independent (readable in major programming languages) 3. Extensibility: the format requires a minimum set of fields to appropriately define a paleoclimate record, but allows for the database to grow organically as more records are added, or - equally important - as more metadata are added to existing records. 4. Citability: The format enables the automatic citation of peer- reviewed articles as well as data citations whenever a data record is being used for analysis, making due recognition of scientific work an automatic part and foundational principle of paleoclimate data analysis. 5. Ergonomy: The format will be easy to use, update and manage. This structure is designed to enable semantic searches, and is expected to help accelerate discovery in all workflows where paleoclimate data are being used. Practical steps towards the implementation of such a system at the community level are then discussed.; Preliminary ontology describing relationships between the data and meta-data fields of the Nurhati et al. [2011] climate record. Several fields are viewed as instances of larger classes (ProxyClass,Site,Reference), which would allow computers to perform operations

Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions.

Science.gov (United States)

Swingedouw, Didier; Ortega, Pablo; Mignot, Juliette; Guilyardi, Eric; Masson-Delmotte, Valérie; Butler, Paul G; Khodri, Myriam; Séférian, Roland

2015-03-30

While bidecadal climate variability has been evidenced in several North Atlantic paleoclimate records, its drivers remain poorly understood. Here we show that the subset of CMIP5 historical climate simulations that produce such bidecadal variability exhibits a robust synchronization, with a maximum in Atlantic Meridional Overturning Circulation (AMOC) 15 years after the 1963 Agung eruption. The mechanisms at play involve salinity advection from the Arctic and explain the timing of Great Salinity Anomalies observed in the 1970s and the 1990s. Simulations, as well as Greenland and Iceland paleoclimate records, indicate that coherent bidecadal cycles were excited following five Agung-like volcanic eruptions of the last millennium. Climate simulations and a conceptual model reveal that destructive interference caused by the Pinatubo 1991 eruption may have damped the observed decreasing trend of the AMOC in the 2000s. Our results imply a long-lasting climatic impact and predictability following the next Agung-like eruption.

Climate and cultural history of the Northeastern Yucatan Peninsula, Quintana Roo, Mexico

Energy Technology Data Exchange (ETDEWEB)

Hodell, D.A. [Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611 (United States); Brenner, M.; Curtis, J.H. [Land Use and Environmental Change Institute (LUECI), University of Florida, Gainesville, FL (United States)

2007-07-15

We inferred the Holocene paleoclimate history of the northeastern Yucatan Peninsula, Mexico, by studying stratigraphic variations in stable isotopes (d 18O and d 13C) and lithologic properties (organic matter and carbonate content) in sediment cores taken in 6.3 and 16.2 m of water from Lake Punta Laguna. We present a simple model to explain the lithologic and isotopic variations, and discuss the inferred paleoclimate history in terms of its relation to ancient Maya cultural development. We find evidence for lower lake level and drier climate at about the same time as each major discontinuity in Maya cultural history: Preclassic Abandonment (150-250 A.D.), Maya Hiatus (534 to 593 A.D.), Terminal Classic Collapse (750-1050 A.D.), and Postclassic Abandonment (mid-fifteenth century). Although these broad temporal correlations suggest climate played a role in Maya cultural evolution, chronological uncertainties preclude a detailed analysis of climate changes and archaeologically documented cultural transformations.

Proxy-to-proxy calibration: Increasing the temporal resolution of quantitative climate reconstructions

OpenAIRE

von Gunten, Lucien; D'Andrea, William J.; Bradley, Raymond S.; Huang, Yongsong

2012-01-01

High-resolution paleoclimate reconstructions are often restricted by the difficulties of sampling geologic archives in great detail and the analytical costs of processing large numbers of samples. Using sediments from Lake Braya Sø, Greenland, we introduce a new method that provides a quantitative high-resolution paleoclimate record by combining measurements of the alkenone unsaturation index ( ) with non-destructive scanning reflectance spectroscopic measurements in the visible range (VIS-RS...

Comparison of the effectiveness of local corticosteroid injection and extracorporeal shock wave therapy in patients with lateral epicondylitis.

Science.gov (United States)

Beyazal, Münevver Serdaroğlu; Devrimsel, Gül

2015-12-01

[Purpose] This study aimed to determine and compare the effectiveness of extracorporeal shock wave therapy and local corticosteroid injection in patients with lateral epicondylitis. [Subjects and Methods] Sixty-four patients with lateral epicondylitis were randomly divided into extracorporeal shock wave therapy and steroid injection groups. Patients were evaluated using hand grip strength, visual analog scale, and short-form McGill pain questionnaire at baseline and at 4 and 12 weeks post-treatment. [Results] Both groups showed statistically significant increase in hand grip strength and decreases on the visual analog scale and short form McGill pain questionnaire overtime. There was no statistically significant difference in the percentage of improvement in hand grip strength and on the short-form McGill pain questionnaire between groups at 4 weeks post-treatment, whereas the extracorporeal shock wave therapy group showed better results on the visual analog scale. The percentages of improvements in all 3 parameters were higher in the extracorporeal shock wave therapy group than in the injection group at 12 weeks post-treatment. [Conclusion] Both the extracorporeal shock wave therapy and steroid injection were safe and effective in the treatment of lateral epicondylitis. However, extracorporeal shock wave therapy demonstrated better outcomes than steroid injection at the long-term follow-up.

A new space-time characterization of Northern Hemisphere drought in model simulations of the past and future as compared to the paleoclimate record

Science.gov (United States)

Coats, S.; Smerdon, J. E.; Stevenson, S.; Fasullo, J.; Otto-Bliesner, B. L.

2017-12-01

The observational record, which provides only limited sampling of past climate variability, has made it difficult to quantitatively analyze the complex spatio-temporal character of drought. To provide a more complete characterization of drought, machine learning based methods that identify drought in three-dimensional space-time are applied to climate model simulations of the last millennium and future, as well as tree-ring based reconstructions of hydroclimate over the Northern Hemisphere extratropics. A focus is given to the most persistent and severe droughts of the past 1000 years. Analyzing reconstructions and simulations in this context allows for a validation of the spatio-temporal character of persistent and severe drought in climate model simulations. Furthermore, the long records provided by the reconstructions and simulations, allows for sufficient sampling to constrain projected changes to the spatio-temporal character of these features using the reconstructions. Along these lines, climate models suggest that there will be large increases in the persistence and severity of droughts over the coming century, but little change in their spatial extent. These models, however, exhibit biases in the spatio-temporal character of persistent and severe drought over parts of the Northern Hemisphere, which may undermine their usefulness for future projections. Despite these limitations, and in contrast to previous claims, there are no systematic changes in the character of persistent and severe droughts in simulations of the historical interval. This suggests that climate models are not systematically overestimating the hydroclimate response to anthropogenic forcing over this period, with critical implications for confidence in hydroclimate projections.

Strengthening CRTD-A's Organizational and Program Capacity ...

International Development Research Centre (IDRC) Digital Library (Canada)

Strengthening CRTD-A's Organizational and Program Capacity (Lebanon) ... Women's Rights and Citizenship framework; to strengthen and rationalize its institutional ... IDRC “unpacks women's empowerment” at McGill University Conference.

Évaluation de l'activité entrepreneuriale dans la région MOAN ...

International Development Research Centre (IDRC) Digital Library (Canada)

Institution. American University of Beirut. Institution Country. Liban. Institution Website ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings ... New funding opportunity for gender equality and climate change.

IDRC “unpacks women's empowerment” at McGill University ...

International Development Research Centre (IDRC) Digital Library (Canada)

14 mars 2018 ... Abonnez-vous à notre bulletin pour recevoir les nouvelles du CRDI chaque mois. Abonnez-vous · Droits d'auteur · Éthique de la recherche · Politique de libre accès · Politique de confidentialité · Transparence · Utilisation du site Web. Suivez-nous; Facebook · Twitter · Youtube · Linked In · RSS Feed.

Modeling Malaria Vector Distribution under Climate Change Scenarios in Kenya

Science.gov (United States)

Ngaina, J. N.

2017-12-01

Projecting the distribution of malaria vectors under climate change is essential for planning integrated vector control strategies for sustaining elimination and preventing reintroduction of malaria. However, in Kenya, little knowledge exists on the possible effects of climate change on malaria vectors. Here we assess the potential impact of future climate change on locally dominant Anopheles vectors including Anopheles gambiae, Anopheles arabiensis, Anopheles merus, Anopheles funestus, Anopheles pharoensis and Anopheles nili. Environmental data (Climate, Land cover and elevation) and primary empirical geo-located species-presence data were identified. The principle of maximum entropy (Maxent) was used to model the species' potential distribution area under paleoclimate, current and future climates. The Maxent model was highly accurate with a statistically significant AUC value. Simulation-based estimates suggest that the environmentally suitable area (ESA) for Anopheles gambiae, An. arabiensis, An. funestus and An. pharoensis would increase under all two scenarios for mid-century (2016-2045), but decrease for end century (2071-2100). An increase in ESA of An. Funestus was estimated under medium stabilizing (RCP4.5) and very heavy (RCP8.5) emission scenarios for mid-century. Our findings can be applied in various ways such as the identification of additional localities where Anopheles malaria vectors may already exist, but has not yet been detected and the recognition of localities where it is likely to spread to. Moreover, it will help guide future sampling location decisions, help with the planning of vector control suites nationally and encourage broader research inquiry into vector species niche modeling

Recent changes of weather patterns in North America. Progress report for period ending April 1, 1994

International Nuclear Information System (INIS)

Kukla, G.J.; Karl, T.

1994-01-01

This report contains information dealing with climatic change in North America. Results gathered from present and previous DOE contracts are discussed. These include: usage of the Historical Climatology Network, characteristics of recent climate change, impacts of increasing anthropogenic greenhouse gases, seasonal trends, geographic and seasonal distribution of temperature anomalies, paleoclimates, weather pattern differences between eastern and western regions, daily temperature variations, general circulation models, and results of oceanic circulation

Evaluating impacts of gender integration on agriculture and food ...

International Development Research Centre (IDRC) Digital Library (Canada)

Evaluating impacts of gender integration on agriculture and food security outcomes ... to and control over land, agricultural technologies, extension services, markets, ... IDRC “unpacks women's empowerment” at McGill University Conference.

Examining the Link Between Television and Unhealthy Eating ...

International Development Research Centre (IDRC) Digital Library (Canada)

Examining the Link Between Television and Unhealthy Eating Among Children in Peru ... television exposure increases unhealthy eating among Peruvian children. ... conference of McGill's Institute for the Study of International Development.

Evaluation of Sr/Ca-based paleoclimate reconstructions in modern and Medieval Diploria strigosa corals in the northeastern Caribbean

Science.gov (United States)

Xu, Y.; Pearson, S. P.; Kilbourne, K.

2013-12-01

period with initial U-series dates near the top of the cores ranging from 1277 × 5 A.D. to 1327 × 5 A.D. Initial Sr/Ca results from the first sub-fossil coral have a seasonal range of 2.65 × 0.27 °C when converted to temperature units with our modern calibration, indicating no significant change from modern times. However, the mean Sr/Ca for this coral is very high (9.388 mmol/mol) compared to the modern corals. We explore the potential causes for this discrepancy in our study. Because reconstructing the mean SST during the Medieval Climate Anomaly may be difficult without temporal overlap with modern corals, our focus is on interannual variability. The coral Sr/Ca based monthly SST anomalies for both modern and sub-fossil corals have larger interannual variances than the instrumental record. One explanation for this is that the SSTs derived from sub-fossil corals are local data for which one expects larger variances than the instrumental data averaged over a 2 x 2 ° grid. This species shows great promise for future paleoclimate reconstructions.

Slarti: A boundary condition editor for a coupled climate model

Science.gov (United States)

Mickelson, S. A.; Jacob, R. L.; Pierrehumbert, R.

2006-12-01

One of the largest barriers to making climate models more flexible is the difficulty in creating new boundary conditions, especially for "deep time" paleoclimate cases where continents are in different positions. Climate models consist of several mutually-interacting component models and the boundary conditions must be consistent between them. We have developed a program called Slarti which uses a Graphical User Interface and a set of consistency rules to aid researchers in creating new, consistent, boundary condition files for the Fast Ocean Atmosphere Model (FOAM). Users can start from existing mask, topography, or bathymetry data or can build a "world" entirely from scratch (e.g. a single island continent). Once a case has been started, users can modify mask, vegetation, bathymetry, topography, and river flow fields by drawing new data through a "paint" interface. Users activate a synchronization button which goes through the fields to eliminate inconsistencies. When the changes are complete and save is selected, Slarti creates all the necessary files for an initial run of FOAM. The data is edited at the highest resolution (the ocean-land surface in FOAM) and then interpolated to the atmosphere resolution. Slarti was implemented in Java to maintain portability across platforms. We also relied heavily on Java Swing components to create the interface. This allowed us to create an object-oriented interface that could be used on many different systems. Since Slarti allows users to visualize their changes, they are able to see areas that may cause problems when the model is ran. Some examples would be lakes from the river flow field and narrow trenches within the bathymetry. Through different checks and options available through its interface, Slarti makes the process of creating new boundary conditions for FOAM easier and faster while reducing the chance for user errors.

Tobacco Control Research, Dissemination and Networking in ...

International Development Research Centre (IDRC) Digital Library (Canada)

Tobacco Control Research, Dissemination and Networking in Lebanon. The Tobacco ... IDRC “unpacks women's empowerment” at McGill University Conference ... New funding opportunity for gender equality and climate change. IDRC is ...

Knowledge in Access in Rural Interconnected Areas Network Phase ...

International Development Research Centre (IDRC) Digital Library (Canada)

Researchers will explore network management issues by -examining KariaNet's ... Institution Country. Lebanon. Institution Website. http://www.aub.edu.lb ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings ...

Recours aux cultures céréalières traditionnelles pour améliorer la ...

International Development Research Centre (IDRC) Digital Library (Canada)

Studies. Physico-chemical and sensory evaluation of commercial chakli and ... conference of McGill's Institute for the Study of International Development. ... Special journal issue highlights IDRC-supported findings on women's paid work.

AFRREV STECH, Vol. 3(2) May, 2014

African Journals Online (AJOL)

Toshiba

2014-05-07

May 7, 2014 ... CDs, DVDs, application software, digital media applications and devices ..... instructional contents via Internet, intranet/ extranet, mobile phone, audio and ..... Unpublished master‟s thesis, McGill University, Montreal. Taylor ...

In vivo and In vitro neurochemical-based assessments of wastewater effluents from the Maumee River area of concern.

Data.gov (United States)

U.S. Environmental Protection Agency — All primary data reported in this paper were generated by non-federal collaborators from the University of Michigan and McGill University. US EPA-ORD personnel...

Evaluating Capacity Development: Experiences from Research and ...

International Development Research Centre (IDRC) Digital Library (Canada)

... contribute to the effort itself and, ultimately, to the organization's performance. ... IDRC “unpacks women's empowerment” at McGill University Conference ... Special journal issue highlights IDRC-supported findings on women's paid work.

Monitoring and Evaluation for the Focus Cities Program in Asia ...

International Development Research Centre (IDRC) Digital Library (Canada)

... for comparing and contrasting the performance of the various Focus Cities ... IDRC “unpacks women's empowerment” at McGill University Conference ... Special journal issue highlights IDRC-supported findings on women's paid work.

Low-level laser therapy to treat fibromyalgia.

Science.gov (United States)

Ruaro, J A; Fréz, A R; Ruaro, M B; Nicolau, R A

2014-11-01

Several clinical treatments have been proposed to manage symptoms of fibromyalgia. Low-level laser therapy (LLLT) may be a useful tool to treat this dysfunction. The aim of this study was to evaluate the effects of LLLT in patients with fibromyalgia. A placebo-controlled, randomized clinical trial was carried out with 20 patients divided randomly into either an LLLT group (n = 10) or a placebo group (n = 10). The LLLT group was treated with a GaAlAs laser (670 nm, 4 J/cm(2) on 18 tender points) three times a week over 4 weeks. Before and after treatment, patients were evaluated with the Fibromyalgia Impact Questionnaire (FIQ), McGill Pain Questionnaire, and visual analog scale (VAS). Data from the FIQ and McGill questionnaire for the treated and control groups were analyzed by paired t tests, and Wilcoxon tests were used to analyze data from the VAS. After LLLT or sham treatment, the number of tender points was significantly reduced in both groups (LLLT, p fibromyalgia symptoms showed significant improvements after LLLT compared to placebo (FIQ, p = 0.0003; McGill, p = 0.0078; and VAS, p = 0.0020). LLLT provided relief from fibromyalgia symptoms in patients and should be further investigated as a therapeutic tool for management in fibromyalgia.

Networks : Empowering Communities through Telecentre Networking

International Development Research Centre (IDRC) Digital Library (Canada)

... Egypt, Syria, Lebanon and Morocco - have pulled together in loose networks for peer support. ... IDRC “unpacks women's empowerment” at McGill University Conference ... New funding opportunity for gender equality and climate change.

Upgrading Lebanese Economic Analytical Capacity | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Lebanon needs to upgrade its analytical capacity within key economic policy ... in contemporary approaches to current policy issues such as privatization, fiscal policy, ... IDRC “unpacks women's empowerment” at McGill University Conference.

Comité de dialogue libano-palestinien (CDLP) - phase II | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Cette subvention permettra au CDLP de fournir au gouvernement du Liban le soutien technique ... IDRC “unpacks women's empowerment” at McGill University Conference ... New funding opportunity for gender equality and climate change.

Don Bates: the medical historian as educator, activist, and historian of science.

Science.gov (United States)

Weisz, George

2009-01-01

The author outlines the academic and extra-academic career of Don Bates as a physician-historian, political activist, and creator of the interdisciplinary Department of Social Studies of Medicine at McGill University.

TTI Phase 2 Institutional Support: Center for the Study of the ...

International Development Research Centre (IDRC) Digital Library (Canada)

... will help enhance its research quality, organizational performance, and policy engagement. ... IDRC “unpacks women's empowerment” at McGill University Conference ... Five world-class research teams are working to develop vaccines for ...

Expanding Provision of Essential Surgical Services through Task ...

International Development Research Centre (IDRC) Digital Library (Canada)

Uganda) ... The World Health Organization (WHO) recognizes the challenges and benefits of a ... IWRA/IDRC webinar on climate change and adaptive water management ... IDRC “unpacks women's empowerment” at McGill University Conference.

Valuing psychiatric patients' stories: belief in and use of the supernatural in the Jamaican psychiatric setting.

Science.gov (United States)

James, Caryl C A B; Carpenter, Karen A; Peltzer, Karl; Weaver, Steve

2014-04-01

The aim of this study was to examine illness presentation and understand how psychiatric patients make meaning of the causes of their mental illnesses. Six Jamaican psychiatric patients were interviewed using the McGill Illness Narrative Interview Schedule. Of the 6, 3 representative case studies were chosen. The hermeneutic phenomenological approach and the common sense model were used in the formulation of patients' explanatory models. Results indicate that psychiatric patients actively conceptualized the causes and resultant treatment of their mental illnesses. Patients' satisfaction and compliance with treatment were dependent on the extent to which practitioners' conceptualization matched their own, as well as practitioners' acknowledgement of patients' concerns about causation, prognosis, and treatment.

Building Afghan Research Capability | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

The program will combine MSc-level training in South Asia and China for Afghan faculty ... professional and management training for less-qualified faculty members, ... IDRC “unpacks women's empowerment” at McGill University Conference.

ICT Enabled Disaster Communications for Vulnerable Caribbean ...

International Development Research Centre (IDRC) Digital Library (Canada)

This project will examine how information and communication technology (ICT) ... IDRC “unpacks women's empowerment” at McGill University Conference ... a new funding opportunity aimed at fostering effective, long-term climate action to ...

Search Results | Page 3 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Results 21 - 30 of 8517 ... New Entrepreneurs and High Performance Enterprises in the Middle East ... Education and eLearning: Challenges and Solutions from Asia ... IDRC “unpacks women's empowerment” at McGill University Conference.

Consolidation of Research Centres on Reconstruction in Haiti ...

International Development Research Centre (IDRC) Digital Library (Canada)

... and process evidence on the impact of their military and civil cooperation efforts. ... and Mexico have begun studying Haiti's social, economic and political problems, ... IDRC “unpacks women's empowerment” at McGill University Conference.

Analysis on paleo-hydrogeological conditions of uranium formation in Sawafuqi uranium deposit

International Nuclear Information System (INIS)

Lin Xiaobin; Hao Weilin; Wang Zhiming

2013-01-01

Sawafuqi uranium deposit is located in Kuergan intermontane basin of the South Tianshan (STS) fold belt. On the basis of regional tectonics, paleogeography, paleoclimate and related data, the evolution of intermontane basin could be divided into three hydrogeological cycles. The relationship of uranium mineralization to each cycle was analyzed from the perspective of the evolution of palaeo-hydrogeological conditions, and the uranium metallogenic model in palaeohydrogeology under strongly constructive background was established. (authors)

"Climate change" and vulnerability analysis: poor will become poorer

OpenAIRE

Ozer, Pierre

2013-01-01

The recent Intergovernmental Panel on Climate Change’s Fifth Assessment Report (IPCC-AR5) considers new evidence of climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes and simulations using climate models. “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warme...

Development and validation of a brief, descriptive Danish pain questionnaire (BDDPQ)

DEFF Research Database (Denmark)

Perkins, F M; Werner, M U; Persson, F

2004-01-01

. chronic), and location of the pain. CONCLUSIONS: A Danish pain questionnaire that subjects and patients can self-administer has been developed and validated relative to the words used in the English McGill Pain questionnaire. The discriminative ability of the questionnaire among some common painful......BACKGROUND: A new pain questionnaire should be simple, be documented to have discriminative function, and be related to previously used questionnaires. METHODS: Word meaning was validated by using bilingual Danish medical students and asking them to translate words taken from the Danish version...... of the McGill pain questionnaire into English. Evaluative word value was estimated using a visual analog scale (VAS). Discriminative function was assessed by having patients with one of six painful conditions (postherpetic neuralgia, phantom limb pain, rheumatoid arthritis, ankle fracture, appendicitis...

Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

DEFF Research Database (Denmark)

Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

2015-01-01

Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenviro......Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track...

2017 IDRC Doctoral Research Awardees | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

McGill University, PhD in Social Work ... on household food security and nutritional status of indigenous women of childbearing age, and young children. ... University of British Columbia, PhD in Resources, Environment and Sustainability.

Publications | Page 272 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Fighting the violet vampire. In the fields of sub-Saharan Africa, Alan Watson and McGill University's Weed Research Group are battling devastating parasites — naturally. Something big was happening in these agricultural fields of.

Climate change between the mid and late Holocene in northern high latitudes – Part 2: Model-data comparisons

Directory of Open Access Journals (Sweden)

K. Holmgren

2010-09-01

Full Text Available The climate response over northern high latitudes to the mid-Holocene orbital forcing has been investigated in three types of PMIP (Paleoclimate Modelling Intercomparison Project simulations with different complexity of the modelled climate system. By first undertaking model-data comparison, an objective selection method has been applied to evaluate the capability of the climate models to reproduce the spatial response pattern seen in proxy data. The possible feedback mechanisms behind the climate response have been explored based on the selected model simulations. Subsequent model-model comparisons indicate the importance of including the different physical feedbacks in the climate models. The comparisons between the proxy-based reconstructions and the best fit selected simulations show that over the northern high latitudes, summer temperature change follows closely the insolation change and shows a common feature with strong warming over land and relatively weak warming over ocean at 6 ka compared to 0 ka. Furthermore, the sea-ice-albedo positive feedback enhances this response. The reconstructions of temperature show a stronger response to enhanced insolation in the annual mean temperature than winter and summer temperature. This is verified in the model simulations and the behaviour is attributed to the larger contribution from the large response in autumn. Despite a smaller insolation during winter at 6 ka, a pronounced warming centre is found over Barents Sea in winter in the simulations, which is also supported by the nearby northern Eurasian continental and Fennoscandian reconstructions. This indicates that in the Arctic region, the response of the ocean and the sea ice to the enhanced summer insolation is more important for the winter temperature than the synchronous decrease of the insolation.

Southern Arizona hydroclimate over the last 3000 years: a comparison of speleothem elemental data and climate model simulations

Science.gov (United States)

King, J.; Harrington, M. D.; Cole, J. E.; Drysdale, R.; Woodhead, J. D.; Fasullo, J.; Stevenson, S.; Otto-Bliesner, B. L.; Overpeck, J. T.; Edwards, R. L.; Henderson, G. M.

2017-12-01

Understanding long-term hydroclimate is particularly important in semiarid regions where prolonged droughts may be exacerbated by a warming climate. In many regions, speleothem trace elements correlate with regional wet and dry climate signals. In the drought-prone Southwestern US (SW), wet and dry episodes are strongly influenced by seasonal changes in atmospheric circulation and teleconnections to remote forcing. Here, we address the need for seasonal moisture reconstructions using paleoclimate and climate model approaches. First, we present a high-resolution (sub-annual) record of speleothem trace elements spanning the last 3000 years from Fort Huachuca Cave, AZ, to investigate the variability of regional seasonal precipitation and sustained regional droughts. In a principal component (PC) analysis of the speleothem, trace elements associated with wet (Sr, Ba) and dry (P, Y, Zn) episodes load strongly and inversely, and the associated PC signals correlate with local gridded precipitation data over the last 50 years (R > 0.6, p external forcings, including volcanic eruptions, in both the speleothem record and the Community Earth System Model's Last Millennium Ensemble (CESM-LME). Notably, ENSO and volcanic forcing have a discernable effect on SW seasonal precipitation in model simulations, particularly when the two processes combine to shift the position of the ITCZ. This integrated analysis of paleodata with climate model results will help us identify and explain discrepancies between these information sources and improve stakeholders' ability to anticipate and prepare for future drought.

Activités de recherche, de diffusion et de réseautage aux fins de la ...

International Development Research Centre (IDRC) Digital Library (Canada)

Country(s). Lebanon, Middle East, Central Asia, Far East Asia, South Asia ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings from ... New funding opportunity for gender equality and climate change. IDRC is ...

Déterminants et conséquences de l'usage du narguilé (pipe à eau ...

International Development Research Centre (IDRC) Digital Library (Canada)

Country(s). Lebanon, Middle East, Central Asia, Far East Asia, South Asia ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings from ... New funding opportunity for gender equality and climate change. IDRC is ...

Soutien au Conseil arabe des sciences sociales | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Country(s). Middle East, Central Asia, Far East Asia, South Asia, Lebanon ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings from ... New funding opportunity for gender equality and climate change. IDRC is ...

Growth and Economic Opportunities for Women | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

GrOW works with research teams around the world to generate evidence on ... Growth and Economic Opportunities for Women ... IDRC “unpacks women's empowerment” at McGill University Conference ... Careers · Contact Us · Site map.

Exploration des technologies de l'information et de la ...

International Development Research Centre (IDRC) Digital Library (Canada)

Exploration des technologies de l'information et de la communication au service ... IDRC “unpacks women's empowerment” at McGill University Conference ... a new funding opportunity aimed at fostering effective, long-term climate action to ...

Alternative Evaluation of the Agrarian Sector in Guatemala 10 Years ...

International Development Research Centre (IDRC) Digital Library (Canada)

Alternative Evaluation of the Agrarian Sector in Guatemala 10 Years after the ... in research and advocacy for agrarian legislation ever since the adoption of the ... conference of McGill's Institute for the Study of International Development.

Synthesis of Evidence for Tobacco Taxation Policy Reform in West ...

International Development Research Centre (IDRC) Digital Library (Canada)

Existing evidence shows that tobacco taxation policies, when they make tobacco ... annual conference of McGill's Institute for the Study of International Development. ... In this ROSSA bulletin: Meet Kathryn Toure, the new regional director of ...

Donner aux chercheurs africains la possibilité d'exercer une ...

International Development Research Centre (IDRC) Digital Library (Canada)

Le renforcement de la capacité des chercheurs d'exercer une influence sur les ... Addressing Africa's unmet need for family planning by intensifying sexual and ... conference of McGill's Institute for the Study of International Development.

Lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern Asia

Science.gov (United States)

Dayem, Katherine E.; Molnar, Peter; Battisti, David S.; Roe, Gerard H.

2010-06-01

values and monthly precipitation amounts can be applied to past conditions, differences of at least 50% in mean annual precipitation would be required to explain the δ18O variations on orbital time scales, which are implausibly large and inconsistent with published GCM results. Similarly, plausible amplitudes of seasonal cycles in amounts or in seasonal variations in δ18O values can account for less than half of the 4-5‰ difference between glacial and interglacial δ18O values from speleothems in China. If seasonal cycles in precipitation account for the amplitudes of δ18O values on paleoclimate timescales, they might do so by extending or contracting the durations of seasons (a frequency modulation of the annual cycle), but not by simply varying the amplitudes of the monthly rainfall amounts or monthly average δ18O values (amplitude modulation). Allowing that several processes can affect seasonal variability in isotopic content, we explore the possibility that one or more of the following processes contribute to variations in δ18O values in Chinese cave speleothems: different source regions of the precipitation, which bring different values of δ18O in vapor; different pathways between the moisture source and the paleorecord site along which exchange of 18O between vapor, surface water, and condensate might differ; a different mix of processes involving condensation and evaporation within the atmosphere; or different types of precipitation. Each may account for part of the range of δ18O values revealed by speleothems, and each might contribute to seasonal differences between past and present that do not scale with monthly or even seasonal precipitation amounts.

A simple model for variations in global mean temperature: implications for decadal variability, the global warming hiatus, and recent temperature rise

Science.gov (United States)

Hu, S.; Fedorov, A. V.

2017-12-01

Global mean surface temperature (GMST) has steadily risen since the mid-19th century, and at the same time experienced significant variations on interannual and decadal timescales. Various mechanisms have been proposed to explain such variations, ranging from the Pacific decadal oscillation to volcanic eruptions. In this study, we construct a simple, physically-based model of GMST variations that incorporates greenhouse gas emissions, ENSO forcing, and stratospheric sulfate aerosols. The model closely reproduces the history of GMST changes since 1880 with the mean squared error about 0.05°C for the past 60 years, smaller than the typical error of GMST observations (see the figure attached). It also accurately captures decadal GMST variations, including the global warming hiatus in the early 21stcentury. This model can be used to understand the causes of the observed GMST variations and requires little computational resource. Our results confirm that weak El Niño activity was the major cause of the recent global warming hiatus, while the rapid temperature rise since 2014 is due to atmospheric heat release during 2014-2016 El Niño conditions in addition to the continuing background global warming trend. The model can be also used to make predictions for next-year GMST in the short term, and future climate projections in the long term. We will also discuss the implications of this simple model for paleoclimate reconstructions and GCM performance evaluations.

An Ice Model That is Consistent with Composite Rheology in GIA Modelling

Science.gov (United States)

Huang, P.; Patrick, W.

2017-12-01

There are several popular approaches in constructing ice history models. One of them is mainly based on thermo-mechanical ice models with forcing or boundary conditions inferred from paleoclimate data. The second one is mainly based on the observed response of the Earth to glacial loading and unloading, a process called Glacial Isostatic Adjustment or GIA. The third approach is a hybrid version of the first and second approaches. In this presentation, we will follow the second approach which also uses geological data such as ice flow, terminal moraine data and simple ice dynamic for the ice sheet re-construction (Peltier & Andrew 1976). The global ice model ICE-6G (Peltier et al. 2015) and all its predecessors (Tushingham & Peltier 1991, Peltier 1994, 1996, 2004, Lambeck et al. 2014) are constructed this way with the assumption that mantle rheology is linear. However, high temperature creep experiments on mantle rocks show that non-linear creep laws can also operate in the mantle. Since both linear (e.g. diffusion creep) and non-linear (e.g. dislocation) creep laws can operate simultaneously in the mantle, mantle rheology is likely composite, where the total creep is the sum of both linear and onlinear creep. Preliminary GIA studies found that composite rheology can fit regional RSL observations better than that from linear rheology(e.g. van der Wal et al. 2010). The aim of this paper is to construct ice models in Laurentia and Fennoscandia using this second approach, but with composite rheology, so that its predictions can fit GIA observations such as global RSL data, land uplift rate and g-dot simultaneously in addition to geological data and simple ice dynamics. The g-dot or gravity-rate-of-change data is from the GRACE gravity mission but with the effects of hydrology removed. Our GIA model is based on the Coupled Laplace-Finite Element method as described in Wu(2004) and van der Wal et al.(2010). It is found that composite rheology generally supports a thicker

Challenging Forced Marriage: Building the Defence and Support ...

International Development Research Centre (IDRC) Digital Library (Canada)

... used as a tool to control women's sexuality and mobility, both physical and social. ... The project will provide research to feed into evidence-based interventions and ... conference of McGill's Institute for the Study of International Development.

Adjusting to Chinese Ascendancy in the Global Clothing Industry ...

International Development Research Centre (IDRC) Digital Library (Canada)

Adjusting to Chinese Ascendancy in the Global Clothing Industry (Africa South of Sahara) ... conference of McGill's Institute for the Study of International Development. ... IDRC partner the World Economic Forum is building a hub for inclusive ...

Enabling Access for the Mentally Challenged (India) | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Such children face obstacles to communication, and this makes it more difficult for ... such an intervention is cost-effective and brings measurable benefit to the lives of ... IDRC “unpacks women's empowerment” at McGill University Conference.

Preventing Gender-based Violence in Senegal | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

... agreements that protect women from violence and has the laws, strategies, and ... and giving them an opportunity to increase their skills in the areas of gender ... conference of McGill's Institute for the Study of International Development.

Mama na Mtoto: Barriers and enablers to gender, equity and scale ...

International Development Research Centre (IDRC) Digital Library (Canada)

Mama na Mtoto: Barriers and enablers to gender, equity and scale-up in Tanzania ... Call for new OWSD Fellowships for Early Career Women Scientists now open ... conference of McGill's Institute for the Study of International Development.

Institutional Assessment: A Framework for Strengthening ...

International Development Research Centre (IDRC) Digital Library (Canada)

It is a working document for assessing institutional capacity — ready to be tested in ... in the Department of Administration and Policy Studies, McGill University, and a partner ... Sharing opportunities for innovation in climate change adaptation.

Corrigendum to "Three climatic cycles recorded in a loess-palaeosol sequence at Semlac (Romania)-Implications for dust accumulation in south-eastern Europe" [Quat. Sci. Rev. 154C (2016) 130-142

Science.gov (United States)

Zeeden, C.; Kels, H.; Hambach, U.; Schulte, P.; Protze, J.; Eckmeier, E.; Marković, S. B.; Klasen, N.; Lehmkuhl, F.

2018-05-01

In the article 'Three climatic cycles recorded in a loess-palaeosol sequence at Semlac (Romania)-Implications for dust accumulation in south-eastern Europe' (Zeeden et al., 2016) we employed rock magnetic and grain size proxy data in combination with OSL- and correlative age models. The data and dating is combined to discuss glacial-interglacial paleoclimate variability in an Eurasian context. This dataset was also interpreted regarding the dust source in the eastern Carpathian (Middle Danube) Basin.

New prescription for traumatic times | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

Those are the tough questions at the heart of the Trauma and Global Health Program, ... at McGill University's Douglas Mental Health University Institute in Montréal. ... While acknowledging the international community has good intentions in ...

Rights and Justice and the Social Web Movement (Latin America ...

International Development Research Centre (IDRC) Digital Library (Canada)

Rights and Justice and the Social Web Movement (Latin America) ... mounted to raise public awareness of the importance of privacy as a human right on the Internet. ... conference of McGill's Institute for the Study of International Development.

Querying Provenance Information: Basic Notions and an Example from Paleoclimate Reconstruction

Science.gov (United States)

Stodden, V.; Ludaescher, B.; Bocinsky, K.; Kintigh, K.; Kohler, T.; McPhillips, T.; Rush, J.

2016-12-01

Computational models are used to reconstruct and explain past environments and to predict likely future environments. For example, Bocinsky and Kohler have performed a 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest. The resulting academic publications not only contain traditional method descriptions, figures, etc. but also links to code and data for basic transparency and reproducibility. Examples include ResearchCompendia.org and the new project "Merging Science and Cyberinfrastructure Pathways: The Whole Tale." Provenance information provides a further critical element to understand a published study and to possibly extend or challenge the findings of the original authors. We present different notions and uses of provenance information using a computational archaeology example, e.g., the common use of "provenance for others" (for transparency and reproducibility), but also the more elusive but equally important use of "provenance for self". To this end, we distinguish prospective provenance (a.k.a. workflow) from retrospective provenance (a.k.a. data lineage) and show how combinations of both forms of provenance can be used to answer different kinds of important questions about a workflow and its execution. Since many workflows are developed using scripting or special purpose languages such as Python and R, we employ an approach and toolkit called YesWorkflow that brings provenance modeling, capture, and querying into the realm of scripting. YesWorkflow employs the basic W3C PROV standard, as well as the ProvONE extension for sharing and exchanging retrospective and prospective provenance information, respectively. Finally, we argue that the utility of provenance information should be maximized by developing different kinds provenance questions and queries during the early phases of computational workflow design and implementation.

Late Quaternary glacier sensitivity to temperature and precipitation distribution in the Southern Alps of New Zealand

Energy Technology Data Exchange (ETDEWEB)

Ann V. Rowan; Simon H. Brocklehurst; David M. Schultz; Mitchell A. Plummer; Leif S. Anderson; Neil F. Glasser

2014-05-01

Glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record. However, the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models. Precipitation is usually treated in a simple manner and yet represents difficult-to-characterize variables such as amount, distribution, and phase. Furthermore, precipitation distributions during a glacial probably differed from present-day interglacial patterns. We applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern Southern Alps of New Zealand. A 2-D model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount. A 1-D model was used to quantify variations in length resulting from interannual climate variability. Assuming that present-day interglacial values represent precipitation distributions during the last glacial, a range of plausible present-day precipitation distributions resulted in uncertainty in the Last Glacial Maximum length of the Pukaki Glacier of 17.1?km (24%) and the Rakaia Glacier of 9.3?km (25%), corresponding to a 0.5°C difference in temperature. Smaller changes in glacier length resulted from a 50% decrease in precipitation amount from present-day values (-14% and -18%) and from a 50% increase in precipitation amount (5% and 9%). Our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty.

Modeling the imprint of Milankovitch cycles on early Pleistocene ice volume

Science.gov (United States)

Roychowdhury, R.; DeConto, R.; Pollard, D.

2017-12-01

Global climate during Quaternary and Late Pliocene (present-3.1 Ma) is characterized by alternating glacial and interglacial conditions. Several proposed theories associate these cycles with variations in the Earth's orbital configuration. In this study, we attempt to address the anomalously strong obliquity forcing in the Late Pliocene/Early Pleistocene ice volume records (41 kyr world), which stands in sharp contrast to the primary cyclicity of insolation, which is at precessional periods (23 kyr). Model results from GCM simulations show that at low eccentricities (e0.015), precessional response is important, and the insolation metrics vary out-of-phase between the two hemispheres. Using simulations from a GCM-driven ice sheet model, we simulate time continuous ice volume changes from Northern and Southern Hemispheres. Under eccentricities lower than 0.015, ice sheets in both hemispheres respond only to obliquity cycle, and grow and melt together (in-phase). If the ice sheet is simulated with eccentricity higher than 0.015, both hemispheres become more sensitive to precessional variation, and vary out-of-phase with each other, which is consistent with proxy observations from the late Pleistocene glaciations. We use the simulated ice volumes from 2.0 to 1.0 ma to empirically calculate global benthic δ18O variations based on the assumption that relationships between collapse and growth of ice-sheets and sea level is linear and symmetric and that the isotopic signature of the individual ice-sheets has not changed with time. Our modeled global benthic δ18O values are broadly consistent with the paleoclimate proxy records such as the LR04 stack.

The Effectiveness of Prenatal Intervention on Pain and Anxiety ...

African Journals Online (AJOL)

The Effectiveness of Prenatal Intervention on Pain and Anxiety during the Process of ... and intensity of pain based on visual analogue scale and McGill scales. The data were analyzed by Statistical Package for the Social Sciences software ...

AIDS Review 2005 : What's Cooking? AIDS and the Politics of Food ...

International Development Research Centre (IDRC) Digital Library (Canada)

It will critically examine how HIV/AIDS is affecting rural small-scale food production, ... IDRC “unpacks women's empowerment” at McGill University Conference ... New website will help record vital life events to improve access to services for all.

Political Role of Tribes : Analysis of Tribalism, Islamism and Gender ...

International Development Research Centre (IDRC) Digital Library (Canada)

Tribal relations are deeply intertwined with political relations. ... When countries such as Jordan and Yemen adopted political pluralism, the political parties ... annuelle de l'Institut d'étude du développement international de l'Université McGill.

Diet-induced metabolic hamster model of nonalcoholic fatty liver disease

Directory of Open Access Journals (Sweden)

Bhathena J

2011-06-01

Full Text Available Jasmine Bhathena, Arun Kulamarva, Christopher Martoni, Aleksandra Malgorzata Urbanska, Meenakshi Malhotra, Arghya Paul, Satya PrakashBiomedical Technology and Cell Therapy Research Laboratory, Department of Biomedical Engineering, Artificial Cells and Organs Research Centre, Faculty of Medicine, McGill University, Montreal, Québec, CanadaBackground: Obesity, hypercholesterolemia, elevated triglycerides, and type 2 diabetes are major risk factors for metabolic syndrome. Hamsters, unlike rats or mice, respond well to diet-induced obesity, increase body mass and adiposity on group housing, and increase food intake due to social confrontation-induced stress. They have a cardiovascular and hepatic system similar to that of humans, and can thus be a useful model for human pathophysiology.Methods: Experiments were planned to develop a diet-induced Bio F1B Golden Syrian hamster model of dyslipidemia and associated nonalcoholic fatty liver disease in the metabolic syndrome. Hamsters were fed a normal control diet, a high-fat/high-cholesterol diet, a high-fat/high-cholesterol/methionine-deficient/choline-devoid diet, and a high-fat/high-cholesterol/choline-deficient diet. Serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, glucose, atherogenic index, and body weight were quantified biweekly. Fat deposition in the liver was observed and assessed following lipid staining with hematoxylin and eosin and with oil red O.Results: In this study, we established a diet-induced Bio F1B Golden Syrian hamster model for studying dyslipidemia and associated nonalcoholic fatty liver disease in the metabolic syndrome. Hyperlipidemia and elevated serum glucose concentrations were induced using this diet. Atherogenic index was elevated, increasing the risk for a cardiovascular event. Histological analysis of liver specimens at the end of four weeks showed increased fat deposition in the liver of animals fed

A Test of the MSEC Method for Paleoclimate and intersite correlations from Late Pleistocene/Holocene cave sites in southern Europe : results from Cova de les Cendres, SE Spain

Directory of Open Access Journals (Sweden)

Brooks Ellwood

2000-01-01

Full Text Available En los ultlmos diez alios, se han utilizado las mediciones de la susceptibilidad magnetica (MS de los sedimentos de los yacimientos arqueologicos en cueva para establecer correlaciones entre yacimientos y una estimacion del paleoclima. Ello es posible porque la MS correspondiente a estos sedimentos es el resultado de los procesos activos del clima en el exterior de las cavidades y las variaciones en las propiedades magneticas de los sedimentos, que finalmente se acumulan en el interior de las cavidades. Una vez que se ban depositado, estos materiales son preservados y su estratigraffa proporciona una informacion sobre el clima que puede ser inferida. En este trabajo, al usar la magnetosusceptibilidad, el metodo de cicloestratigrafia (MSEC y la correlacion grafica, presentamos informacion sobre la Cova de les Cendres y situamos estos resultados en un marco paleoclimatico que abarca los ultimos 43.000 anos (fechas BP sin calibrar de la Europa meridional. Estos resultados correlacionan bien con otros indicadores independientes de clima. Ademas, a causa de que los sedimentos de la parte superior de la Cova de les Cendres se depositaron relativamente rapidos, es posible observar cambios climaticos de escala ultra-fina en los dates de esta parte de la secuencia en la cavidad.During the last 10 years or so, magnetic susceptibility (MS measurements of cave sediments from archaeological sites have been used for intra-site correlation and paleoclimate estimation. This is possible because the MS of these sediments results from climate processes active outside caves causing variations in magnetic properties of the sediments ultimately accumulating inside of caves. Once deposited, these materials are preserved and their stratigraphy provides a climate proxy that can be extracted. Here, using the magnetosusceptibility event and cyclostratigraphy (MSEC method and graphic correlation, we present data from Cova de les Cendres and place these results into a

Search Results | Page 824 | IDRC - International Development ...

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Results 8231 - 8240 of 8494 ... ... and barriers to use of maternal and child health services in Papua New ... Caribbean health : diversity in local food production to combat obesity. Led by researchers from McGill University and the University of the ...

LGM permafrost distribution: how well can the latest PMIP multi-model ensembles reconstruct?

Science.gov (United States)

Saito, K.; Sueyoshi, T.; Marchenko, S.; Romanovsky, V.; Otto-Bliesner, B.; Walsh, J.; Bigelow, N.; Hendricks, A.; Yoshikawa, K.

2013-03-01

Global-scale frozen ground distribution during the Last Glacial Maximum (LGM) was reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present-day (pre-industrial; 0 k) and the LGM (21 k). This direct method was then compared to the earlier indirect method, which categorizes the underlying frozen ground type from surface air temperature, applied to both the PMIP2 (phase II) and PMIP3 products. Both direct and indirect diagnoses for 0 k showed strong agreement with the present-day observation-based map, although the soil temperature ensemble showed a higher diversity among the models partly due to varying complexity of the implemented subsurface processes. The area of continuous permafrost estimated by the multi-model analysis was 25.6 million km2 for LGM, in contrast to 12.7 million km2 for the pre-industrial control, whereas seasonally, frozen ground increased from 22.5 million km2 to 32.6 million km2. These changes in area resulted mainly from a cooler climate at LGM, but other factors as well, such as the presence of huge land ice sheets and the consequent expansion of total land area due to sea-level change. LGM permafrost boundaries modeled by the PMIP3 ensemble-improved over those of the PMIP2 due to higher spatial resolutions and improved climatology-also compared better to previous knowledge derived from the geomorphological and geocryological evidences. Combinatorial applications of coupled climate models and detailed stand-alone physical-ecological models for the cold-region terrestrial, paleo-, and modern climates will advance our understanding of the functionality and variability of the frozen ground subsystem in the global eco-climate system.

Impact of prehistoric cooking practices on paleoenvironmental proxies in shell midden constituents

Science.gov (United States)

Müller, Peter; Staudigel, Philip; Murray, Sean T.; Westphal, Hildegard; Swart, Peter K.

2016-04-01

Paleoenvironmental proxy records such as oxygen isotopes of calcareous skeletal structures like fish otoliths or mollusk shells provide highest-resolution information about environmental conditions experienced by the organism. Accumulations of such skeletal structures by ancient coastal populations in so called "shell midden" deposits provide us with sub-seasonally resolved paleoclimate records covering time spans up to several millennia. Given their high temporal resolution, these deposits are increasingly used for paleoclimate reconstructions and complement our understanding of ancient climate changes. However, gathered as comestibles, most of these skeletal remains were subject to prehistoric cooking methods prior to deposition. The associated alteration of the chemical proxy signatures as well as the subsequent error for paleoenvironmental reconstructions remained almost entirely neglected so far. Here, we present clumped isotope, conventional oxygen and carbon isotopes as well as element:Ca ratios measured in modern bivalve shells after exposing them to different prehistoric cooking methods. Our data show that most cooking methods considerably alter commonly used paleoclimate proxy systems which can lead to substantial misinterpretations of ancient climate conditions. Since the magnitude of chemical alteration is not distinguishable from natural temperature variability in most coastal settings, the alteration of shell midden constituents by prehistoric cooking remains likely unnoticed in most cases. Thus, depending on the cooking method, pre-depositional heating might have introduced considerable errors into previous paleoclimate studies. However, our data also show that clumped isotope thermometry represents a suitable diagnostic tool to detect such pre-depositional cooking events and also allows differentiating between the most commonly applied prehistoric cooking methods.

Modern Climate Analogues of Late-Quaternary Paleoclimates for the Western United States.

Science.gov (United States)

Mock, Cary Jeffrey

This study examined spatial variations of modern and late-Quaternary climates for the western United States. Synoptic climatological analyses of the modern record identified the predominate climatic controls that normally produce the principal modes of spatial climatic variability. They also provided a modern standard to assess past climates. Maps of the month-to-month changes in 500 mb heights, sea-level pressure, temperature, and precipitation illustrated how different climatic controls govern the annual cycle of climatic response. The patterns of precipitation ratios, precipitation bar graphs, and the seasonal precipitation maximum provided additional insight into how different climatic controls influence spatial climatic variations. Synoptic-scale patterns from general circulation model (GCM) simulations or from analyses of climatic indices were used as the basis for finding modern climate analogues for 18 ka and 9 ka. Composite anomaly maps of atmospheric circulation, precipitation, and temperature were compared with effective moisture maps compiled from proxy data to infer how the patterns, which were evident from the proxy data, were generated. The analyses of the modern synoptic climatology indicate that smaller-scale climatic controls must be considered along with larger-scale ones in order to explain patterns of spatial climate heterogeneity. Climatic extremes indicate that changes in the spatial patterns of precipitation seasonality are the exception rather than the rule, reflecting the strong influence of smaller-scale controls. Modern climate analogues for both 18 ka and 9 ka clearly depict the dry Northwest/wet Southwest contrast that is suggested by GCM simulations and paleoclimatic evidence. 18 ka analogues also show the importance of smaller-scale climatic controls in explaining spatial climatic variation in the Northwest and northern Great Plains. 9 ka analogues provide climatological explanations for patterns of spatial heterogeneity over several

Predicting the Future at Yucca Mountain

International Nuclear Information System (INIS)

Wilson, J. R.

1999-01-01

This paper summarizes a climate-prediction model funded by the DOE for the Yucca Mountain nuclear waste repository. Several articles in the open literature attest to the effects of the Global Ocean Conveyor upon paleoclimate, specifically entrance and exit from the ice age. The data shows that these millennial-scale effects are duplicated on the microscale of years to decades. This work also identifies how man may have influenced the Conveyor, affecting global cooling and warming for 2,000 years

The climatic out of control. the climatic forcing; L'emballement climatique. Le forcage climatique

Energy Technology Data Exchange (ETDEWEB)

Bony-Lena, S.; Dufresne, J.L. [Laboratoire de Meteorologie Dynamique, LMD/IPSL, CNRS-UPMC, 75 - Paris (France); Acot, P. [Institut d' histoire et de philosophie des sciences et des techniques (IHPST), CNRS-Univ. Paris-1-ENS, 75 - Paris (France); Friedlingstein, P. [CEA Saclay, Lab. des Sciences du Climat et l' Environnement (LSCE), 91 - Gif-sur-Yvette (France); Berger, A.; Loutre, M.L. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium). Inst. d' Astronomie et de Geophysique G. Lemaitre; Jouzel, J. [Institut Pierre Simon Laplace, 75 - Paris (France); Raynaud, D. [Laboratoire de Glaciologie et Geophysique de l' Environnement (UMR 5183), 38 - Saint Martin d' Heres cedex (France); Thuiller, W. [Universite Joseph-Fourier, Lab. d' Ecologie Alpine, CNRS-Univ. Grenoble-1, 38 (France); Le Treut, H. [Laboratoire de Meteorologie dynamique du CNRS, 75 - Paris (France); Houssais, M.N. [Laboratoire d' Oceanographie et du Climat Experimentation et Approches Numerique (LOCEAN / IPSL), 75 - Paris (France); Duplessy, J.C. [Centre National de la Recherche Scientifique, Laboratoire des Sciences du Climat et de l' Environnement (LSCE), 91 - Gif sur Yvette (France); Royer, J.F.; Douville, H. [Centre National de Recherches Meteorologiques, 31 - Toulouse (France); Barberousse, A. [Institut d' Histoire et de Philosophie des Sciences et des Techniques, CNRS, ENS, 75 - Paris (France); Quinon, P

2007-03-15

The expert group on the climate evolution affirms that the global warming is unequivocal and that the human being is the main responsible. This document broaches the climatic change under many aspects: the principle, the historical aspect of the greenhouse effect, the GIEC, the carbon cycle, the paleo-climate theory, the antarctic ices and the impacts of the climatic change on the biodiversity, the simulations and the models, the climatic indicators and the climatic forcing by human activities. (A.L.B.)

The climatic out of control. the climatic forcing

International Nuclear Information System (INIS)

Bony-Lena, S.; Dufresne, J.L.; Acot, P.; Friedlingstein, P.; Berger, A.; Loutre, M.L.; Raynaud, D.; Thuiller, W.; Le Treut, H.; Houssais, M.N.; Duplessy, J.C.; Royer, J.F.; Douville, H.; Barberousse, A.; Quinon, P.

2007-01-01

The expert group on the climate evolution affirms that the global warming is unequivocal and that the human being is the main responsible. This document broaches the climatic change under many aspects: the principle, the historical aspect of the greenhouse effect, the GIEC, the carbon cycle, the paleo-climate theory, the antarctic ices and the impacts of the climatic change on the biodiversity, the simulations and the models, the climatic indicators and the climatic forcing by human activities. (A.L.B.)

Predicting the Future at Yucca Mountain

Energy Technology Data Exchange (ETDEWEB)

J. R. Wilson

1999-07-01

This paper summarizes a climate-prediction model funded by the DOE for the Yucca Mountain nuclear waste repository. Several articles in the open literature attest to the effects of the Global Ocean Conveyor upon paleoclimate, specifically entrance and exit from the ice age. The data shows that these millennial-scale effects are duplicated on the microscale of years to decades. This work also identifies how man may have influenced the Conveyor, affecting global cooling and warming for 2,000 years.

Los yacimientos de vertebrados del Mioceno medio de Somosaguas (Pozuelo de Alarcón, Madrid: implicaciones paleoambientales y paleoclimáticas

Directory of Open Access Journals (Sweden)

López Martínez, N.

2006-12-01

nueva de hámster (Cricetodon soriae nov. sp.. La sucesión muestra varios episodios de coladas de tipo debris-flow con transporte de huesos, rocas y arcosas discordantes por debajo y por encima de un relleno lacustre. Los depósitos contienen una secuencia de alteración de micas con arcillas de neoformación progresivamente más evolucionadas y vetas de caliche hacia techo, indicando aridez creciente. La riqueza del conjunto de macro y microvertebrados de los yacimientos de Somosaguas permite relacionarlo con el de otros yacimientos de edad similar, resultando en un patrón biogeográfico de transición paleártico-paleotropical. Esto coincide con los datos paleoclimáticos aportados por la fauna de mamíferos, que indican la existencia de condiciones tropicales con estacionalidad hídrica muy marcada. Se infiere la existencia en el área de un mosaico de ambientes dentro de un bioma de sabana, combinando áreas abiertas y bosquetes asociados al medio lacustre. El análisis isotópico indica un progresivo enfriamiento y aridez, que se correlaciona con los cambios climáticos inferidos a escala global en este período, hace unos 14 millones de años.

A Paleolatitude Calculator for Paleoclimate Studies

NARCIS (Netherlands)

Van Hinsbergen, D.J.J.; De Groot, L.V.; Van Schaik, S.J.; Spakman, W.; Bijl, P.K.; Sluijs, A.; Langereis, C.G.; Brinkhuis, H.

2015-01-01

Realistic appraisal of paleoclimatic information obtained from a particular location requires accurate knowledge of its paleolatitude defined relative to the Earth’s spin-axis. This is crucial to, among others, correctly assess the amount of solar energy received at a location at the moment of

Effects of transurethral resection of prostate on the quality of life of patients with benign prostatic hyperplasia.

LENUS (Irish Health Repository)

O'Sullivan, MartinJ

2012-02-03

BACKGROUND: This article investigated the effects of transurethral resection of prostate on quality of life (QOL) and urinary symptoms in patients with benign prostatic hyperplasia (BPH). STUDY DESIGN: In a prospective study, 30 patients without significant comorbidities undergoing transurethral resection of prostate for BPH were studied. Patients completed four validated questionnaires: the International Prostate Symptom Score and the associated QOL index because urinary symptoms, the Montgomery and Asberg Depression Rating Scale, the McGill Pain Questionnaire, and the QOL questionnaire Short Form-36. These were completed preoperatively, on the first postoperative day, on discharge from hospital, and at 1 and 3 months postoperatively. RESULTS: The QOL of patients who undergo transurethral resection of prostate for BPH had significantly improved at 3 months after their operation. The International Prostate Symptom Score scores at 1 month (9.3+\\/-4.6) and 3 months (5.4+\\/-5.6) were less than they were preoperatively (19.9+\\/-7.1). The QOL index because urinary symptoms was less at 1 month (2.4+\\/-1.9) and at 3 months postoperatively (1.5+\\/-1.4) in comparison with the preoperative scores (4.5+\\/-1.2). The Montgomery and Asberg Depression Rating Scale scores at 1 month (5.4+\\/-6.8) and 3 months (4.9+\\/-6.5) were less than they were preoperatively (9.2+\\/-8.3). The McGill Pain Questionnaire sensory and pain rating index scores were less at 3 months than they were preoperatively (p=0.02 and p<0.02 respectively). The McGill Pain Questionnaire affective score was less at 1 month than it was preoperatively (p<0.03). The McGill Pain Questionnaire evaluative scores were less than the preoperative score at all times postoperatively. The role physical (p=0.007), bodily pain (p=0.006), social function (p=0.007), and physical component summary (p=0.007) subsections of the Short Form-36 were greater at 3 months postoperatively when compared with the preoperative scores

Risques et possibilités liés aux changements climatiques pour les ...

International Development Research Centre (IDRC) Digital Library (Canada)

... aussi d'évaluer le potentiel que représentent ces marchés innovants pour inciter les ... de un Nuevo Sector en la Economía Sistema B. Institution Country. Chile ... IDRC “unpacks women's empowerment” at McGill University Conference.

Tritherapy (Spinalon)-Elicited Spinal Locomotor Network Activation: Phase I-IIa Clinical Trial in Spinal Cord-Injured Patients

Science.gov (United States)

2013-10-01

rollerblade, ski, fishing, travel,music, cinema and computer. OTIIER RELEVANT fNFORMATION LANGUAGES: English & French THERAPEUTIC EXPERIENCE: See...Revised English and French Consent Form dated 25 January 2013 • Advert isement (English and French ) The Research Ethics Boards (REBs) of the McGill

Building Businesses with Small Producers : Successful Business ...

International Development Research Centre (IDRC) Digital Library (Canada)

La recherche analysée dans cet ouvrage apporte une contribution ... de coopération scientifique et technologique en appui aux projets de recherche conjoints. ... de l'Institut d'étude du développement international de l'Université McGill.

Adaptation aux changements climatiques dans le bassin versant de ...

International Development Research Centre (IDRC) Digital Library (Canada)

... hydrologiques et agronomiques, les chercheurs étudieront l'évolution de la ... de coopération scientifique et technologique en appui aux projets de recherche ... de l'Institut d'étude du développement international de l'Université McGill.

Development and validation of a brief, descriptive Danish pain questionnaire (BDDPQ)

DEFF Research Database (Denmark)

Perkins, F M; Werner, M U; Persson, F

2004-01-01

of the McGill pain questionnaire into English. Evaluative word value was estimated using a visual analog scale (VAS). Discriminative function was assessed by having patients with one of six painful conditions (postherpetic neuralgia, phantom limb pain, rheumatoid arthritis, ankle fracture, appendicitis...

Solar stills for agricultural purposes

Science.gov (United States)

Selcuk, M. K.; Tran, V. V.

1975-01-01

Basic concepts of using desalinated water for agricultural purposes are outlined. A mathematical model describing heat and mass transfer in a system combining a solar still with a greenhouse, its solution, and test results of a small-scale unit built at the Middle East Technical University, Ankara, Turkey, are discussed. The unit was employed to demonstrate the technical feasibility of the system. Further development and modifications are necessary for larger-scale operations. The basis of an optimization study which is underway at the Brace Research Institute of McGill University in Montreal, Canada, aimed at finding the best combination of design and operation parameters is also presented.

Comparing proxy and model estimates of hydroclimate variability and change over the Common Era

Science.gov (United States)

Hydro2k Consortium, Pages

2017-12-01

Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy-model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform

LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction?

Directory of Open Access Journals (Sweden)

K. Saito

2013-08-01

Full Text Available Here, global-scale frozen ground distribution from the Last Glacial Maximum (LGM has been reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project phase III (PMIP3 simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present day (pre-industrial; 0 kya and the LGM (21 kya. This direct method was then compared to an earlier indirect method, which categorizes underlying frozen ground type from surface air temperature, applying to both the PMIP2 (phase II and PMIP3 products. Both direct and indirect diagnoses for 0 kya showed strong agreement with the present-day observation-based map. The soil temperature ensemble showed a higher diversity around the border between permafrost and seasonally frozen ground among the models, partly due to varying subsurface processes, implementation, and settings. The area of continuous permafrost estimated by the PMIP3 multi-model analysis through the direct (indirect method was 26.0 (17.7 million km2 for LGM, in contrast to 15.1 (11.2 million km2 for the pre-industrial control, whereas seasonally frozen ground decreased from 34.5 (26.6 million km2 to 18.1 (16.0 million km2. These changes in area resulted mainly from a cooler climate at LGM, but from other factors as well, such as the presence of huge land ice sheets and the consequent expansion of total land area due to sea-level change. LGM permafrost boundaries modeled by the PMIP3 ensemble – improved over those of the PMIP2 due to higher spatial resolutions and improved climatology – also compared better to previous knowledge derived from geomorphological and geocryological evidence. Combinatorial applications of coupled climate models and detailed stand-alone physical-ecological models for the cold-region terrestrial

LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction?

Science.gov (United States)

Saito, K.; Sueyoshi, T.; Marchenko, S.; Romanovsky, V.; Otto-Bliesner, B.; Walsh, J.; Bigelow, N.; Hendricks, A.; Yoshikawa, K.

2013-08-01

Here, global-scale frozen ground distribution from the Last Glacial Maximum (LGM) has been reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project phase III (PMIP3) simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present day (pre-industrial; 0 kya) and the LGM (21 kya). This direct method was then compared to an earlier indirect method, which categorizes underlying frozen ground type from surface air temperature, applying to both the PMIP2 (phase II) and PMIP3 products. Both direct and indirect diagnoses for 0 kya showed strong agreement with the present-day observation-based map. The soil temperature ensemble showed a higher diversity around the border between permafrost and seasonally frozen ground among the models, partly due to varying subsurface processes, implementation, and settings. The area of continuous permafrost estimated by the PMIP3 multi-model analysis through the direct (indirect) method was 26.0 (17.7) million km2 for LGM, in contrast to 15.1 (11.2) million km2 for the pre-industrial control, whereas seasonally frozen ground decreased from 34.5 (26.6) million km2 to 18.1 (16.0) million km2. These changes in area resulted mainly from a cooler climate at LGM, but from other factors as well, such as the presence of huge land ice sheets and the consequent expansion of total land area due to sea-level change. LGM permafrost boundaries modeled by the PMIP3 ensemble - improved over those of the PMIP2 due to higher spatial resolutions and improved climatology - also compared better to previous knowledge derived from geomorphological and geocryological evidence. Combinatorial applications of coupled climate models and detailed stand-alone physical-ecological models for the cold-region terrestrial, paleo-, and modern

The Androgen Receptor Gene Mutations Database.

Science.gov (United States)

Gottlieb, B; Lehvaslaiho, H; Beitel, L K; Lumbroso, R; Pinsky, L; Trifiro, M

1998-01-01

The current version of the androgen receptor (AR) gene mutations database is described. The total number of reported mutations has risen from 272 to 309 in the past year. We have expanded the database: (i) by giving each entry an accession number; (ii) by adding information on the length of polymorphic polyglutamine (polyGln) and polyglycine (polyGly) tracts in exon 1; (iii) by adding information on large gene deletions; (iv) by providing a direct link with a completely searchable database (courtesy EMBL-European Bioinformatics Institute). The addition of the exon 1 polymorphisms is discussed in light of their possible relevance as markers for predisposition to prostate or breast cancer. The database is also available on the internet (http://www.mcgill. ca/androgendb/ ), from EMBL-European Bioinformatics Institute (ftp. ebi.ac.uk/pub/databases/androgen ), or as a Macintosh FilemakerPro or Word file (MC33@musica.mcgill.ca).

[Effectiveness of aquatic biodance on sleep quality, anxiety and other symptoms in patients with fibromyalgia].

Science.gov (United States)

López-Rodríguez, María Mar; Fernández-Martínez, Manuel; Matarán-Peñarrocha, Guillermo A; Rodríguez-Ferrer, María Encarnación; Granados Gámez, Genoveva; Aguilar Ferrándiz, Encarnación

2013-12-07

To analyze the effects of an aquatic biodance based therapy on sleep quality, anxiety, depression, pain and quality of life in fibromyalgia patients. Randomized controlled trial with 2 groups. Fifty-nine patients were assigned to 2 groups: experimental group (aquatic biodance) and control group (stretching). The outcome measures were quality of sleep (Pittsburgh questionnaire), anxiety (State Anxiety Inventory), depression (Center for Epidemiologic Studies Depression Scale), pain (visual analogue scale, pressure algometry and McGill) and quality of life (Fibromyalgia Impact Questionnaire) before and after a 12-week therapy. After treatment, we observed significant differences in the experimental group (Pquality (49.7%), anxiety (14.1%), impact of fibromyalgia (18.3%), pain (27.9%), McGill (23.7%) and tender points (34.4%). Aquatic biodance contributed to improvements in sleep quality, anxiety, pain and other fibromyalgia symptoms. Copyright © 2012 Elsevier España, S.L. All rights reserved.

The Precession Index and a Nonlinear Energy Balance Climate Model

Science.gov (United States)

Rubincam, David

2004-01-01

A simple nonlinear energy balance climate model yields a precession index-like term in the temperature. Despite its importance in the geologic record, the precession index e sin (Omega)S, where e is the Earth's orbital eccentricity and (Omega)S is the Sun's perigee in the geocentric frame, is not present in the insolation at the top of the atmosphere. Hence there is no one-for-one mapping of 23,000 and 19,000 year periodicities from the insolation to the paleoclimate record; a nonlinear climate model is needed to produce these long periods. A nonlinear energy balance climate model with radiative terms of form T n, where T is surface temperature and n less than 1, does produce e sin (omega)S terms in temperature; the e sin (omega)S terms are called Seversmith psychroterms. Without feedback mechanisms, the model achieves extreme values of 0.64 K at the maximum orbital eccentricity of 0.06, cooling one hemisphere while simultaneously warming the other; the hemisphere over which perihelion occurs is the cooler. In other words, the nonlinear energy balance model produces long-term cooling in the northern hemisphere when the Sun's perihelion is near northern summer solstice and long-term warming in the northern hemisphere when the aphelion is near northern summer solstice. (This behavior is similar to the inertialess gray body which radiates like T 4, but the amplitude is much lower for the energy balance model because of its thermal inertia.) This seemingly paradoxical behavior works against the standard Milankovitch model, which requires cool northern summers (Sun far from Earth in northern summer) to build up northern ice sheets, so that if the standard model is correct it must be more efficient than previously thought. Alternatively, the new mechanism could possibly be dominant and indicate southern hemisphere control of the northern ice sheets, wherein the southern oceans undergo a long-term cooling when the Sun is far from the Earth during northern summer. The cold

Brahmayya Sastry, Dr Podila

Indian Academy of Sciences (India)

Elected: 1978 Section: Medicine. Brahmayya Sastry, Dr Podila Ph.D. (McGill). Date of birth: 24 May 1913. Date of death: 28 May 1993. Specialization: Physiology, Neurophysiology and Placental Physiology Last known address: Sitaramanilayam, Plot No. 9, Doctors Co-Operative Housing Colony, Waltair, Visakhapatnam ...

Fonds GenARDIS (Genre, agriculture, développement rural et ...

International Development Research Centre (IDRC) Digital Library (Canada)

La diffusion des rapports de recherche et des constatations sera assurée par une ... de coopération scientifique et technologique en appui aux projets de recherche ... de l'Institut d'étude du développement international de l'Université McGill.

Pensions alimentaires pour enfants, pauvreté et égalité entre les ...

International Development Research Centre (IDRC) Digital Library (Canada)

... les politiques quant au contenu et à l'administration du droit familial dans les ... un accord de coopération scientifique et technologique en appui aux projets de ... de l'Institut d'étude du développement international de l'Université McGill.

Modèles commerciaux libres (Amérique latine) - phase II | CRDI ...

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... ne reposant pas essentiellement sur les droits de propriété intellectuelle comme ... un accord de coopération scientifique et technologique en appui aux projets de ... de l'Institut d'étude du développement international de l'Université McGill.

Jeunesse sud-américaine et intégration - recensement des ...

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... par rapport aux structures et aux politiques institutionnelles et en quoi ce facteur ... ont conclu un accord de coopération scientifique et technologique en appui aux ... de l'Institut d'étude du développement international de l'Université McGill.

Foreign Direct Investment Behaviour in Low and Middle Income ...

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Are policies and institutional structures equally effective in attracting FDI to low- and ... ont conclu un accord de coopération scientifique et technologique en appui aux ... de l'Institut d'étude du développement international de l'Université McGill.

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Université McGill. « Unpacking Women's Empowerment: Implications for Research, Policy, and Practice in International Development », le thème de la conférence de cette année (les 15 et 16. Date de publication. 14 mars 2018. Research in Action.

Résultats de recherche | Page 2 | CRDI - Centre de recherches pour ...

International Development Research Centre (IDRC) Digital Library (Canada)

Université McGill. « Unpacking Women's Empowerment: Implications for Research, Policy, and Practice in International Development », le thème de la conférence de cette année (les 15 et 16. Date de publication. 14 mars 2018. Research in Action.

Pilot Project Using ICTs to Monitor Chagas' Disease in Argentina ...

International Development Research Centre (IDRC) Digital Library (Canada)

Argentina, South America, Bolivia, Brazil, North and Central America ... the annual conference of McGill's Institute for the Study of International Development. ... Special journal issue highlights IDRC-supported findings on women's paid work ... in India, including heat stress, water management, and climate-related migration.

Centre for Environmental Economics and Policy in Africa | Page 2 ...

International Development Research Centre (IDRC) Digital Library (Canada)

... in Africa : an analysis of the efficacy of fuel taxation for pollution control in South Africa ... de l'Institut d'étude du développement international de l'Université McGill ... Dans ce bulletin du BRAS: Faites connaissance avec Kathryn Touré, ...

An overview of the Yucca Mountain Global/Regional Climate Modeling Program

International Nuclear Information System (INIS)

Sandoval, R.P.; Behl, Y.K.; Thompson, S.L.

1992-01-01

The US Department of Energy (DOE) has developed a site characterization plan (SCP) to collect detailed information on geology, geohydrology, geochemistry, geoengineering, hydrology, climate, and meteorology (collectively referred to as ''geologic information'') of the Yucca Mountain site. This information will be used to determine if a mined geologic disposal system (MGDS) capable of isolating high-level radioactive waste without adverse effects to public health and safety over 10,000 years, as required by regulations 40 CFR Part 191 and 10 CFR Part 60, could be constructed at the Yucca Mountain site. Forecasts of future climates conditions for the Yucca Mountain area will be based on both empirical and numerical techniques. The empirical modeling is based on the assumption that future climate change will follow past patterns. In this approach, paleclimate records will be analyzed to estimate the nature, timing, and probability of occurrence of certain climate states such as glacials and interglacials over the next 10,000 years. For a given state, key climate parameters such as precipitation and temperature will be assumed to be the same as determined from the paleoclimate data. The numerical approach, which is the primary focus of this paper, involves the numerical solution of basic equations associated with atmospheric motions. This paper describes these equations and the strategy for solving them to predict future climate conditions around Yucca Mountain

Impacts of peatland and permafrost changes on the terrestrial carbon storage over the last 21 ka

Science.gov (United States)

Spahni, Renato; Stocker, Benjamin D.; Joos, Fortunat

2014-05-01

Paleoclimate records and global climate-carbon cycle models suggest a net increase in land carbon (C) storage between 300 and 700 Pg C (1 Pg C = 1015 g C) during the transition from the last glacial maximum (LGM), the Holocene up to the preindustrial period. Peat accumulation rate records imply an increase in peatland C of ~600 Pg C over the course of the Holocene. In high northern latitudes mineral and organic soils are subject to permafrost formation, which is believed to have been more extensive during glacial compared to interglacial periods. Soil C in permafrost regions represents the largest inert C pool on land at present. The spatio-temporal evolution, however, of C stocks in soils and vegetation remains poorly quantified and is uncertain. Here, the Land surface Processes and eXchanges (LPX-Bern) Dynamic Global Vegetation Model is applied in transient simulations to explore the evolution of permafrost, peatland and vegetation C over the last 21'000 years. The model is forced with temperature and precipitation output from the Trace-21ka climate simulation, and dynamically simulates the formation and disappearance of peatlands and permafrost soils, vegetation distribution and C stocks. Results indicate that peatlands and permfrost areas existed further south in the LGM, in agreement with available proxy information, and that their associated C was lost during the transition into the Holocene. The simulated loss of inert C is over-compensated by vegetation regrowth. The timing of the C relocation on land is compared to observational evidence from paleoclimate archives and estimates from ocean C inventory changes.

The PMIP4 Contribution to CMIP6-Part 4: Scientific Objectives and Experimental Design of the PMIP4-CMIP6 Last Glacial Maximum Experiments and PMIP4 Sensitivity Experiments

Science.gov (United States)

Kageyama, Masa; Albani, Samuel; Braconnot, Pascale; Harrison, Sandy P.; Hopcroft, Peter O.; Ivanovic, Ruza F.; Lambert, Fabrice; Marti, Olivier; Peltier, W. Richard; Peterschmitt, Jean-Yves;

The PMIP4 contribution to CMIP6 - Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments

Science.gov (United States)

Kageyama, Masa; Albani, Samuel; Braconnot, Pascale; Harrison, Sandy P.; Hopcroft, Peter O.; Ivanovic, Ruza F.; Lambert, Fabrice; Marti, Olivier; Peltier, W. Richard; Peterschmitt, Jean-Yves; Roche, Didier M.; Tarasov, Lev; Zhang, Xu; Brady, Esther C.; Haywood, Alan M.; LeGrande, Allegra N.; Lunt, Daniel J.; Mahowald, Natalie M.; Mikolajewicz, Uwe; Nisancioglu, Kerim H.; Otto-Bliesner, Bette L.; Renssen, Hans; Tomas, Robert A.; Zhang, Qiong; Abe-Ouchi, Ayako; Bartlein, Patrick J.; Cao, Jian; Li, Qiang; Lohmann, Gerrit; Ohgaito, Rumi; Shi, Xiaoxu; Volodin, Evgeny; Yoshida, Kohei; Zhang, Xiao; Zheng, Weipeng

2017-11-01

The Last Glacial Maximum (LGM, 21 000 years ago) is one of the suite of paleoclimate simulations included in the current phase of the Coupled Model Intercomparison Project (CMIP6). It is an interval when insolation was similar to the present, but global ice volume was at a maximum, eustatic sea level was at or close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. The LGM has been a focus for the Paleoclimate Modelling Intercomparison Project (PMIP) since its inception, and thus many of the problems that might be associated with simulating such a radically different climate are well documented. The LGM state provides an ideal case study for evaluating climate model performance because the changes in forcing and temperature between the LGM and pre-industrial are of the same order of magnitude as those projected for the end of the 21st century. Thus, the CMIP6 LGM experiment could provide additional information that can be used to constrain estimates of climate sensitivity. The design of the Tier 1 LGM experiment (lgm) includes an assessment of uncertainties in boundary conditions, in particular through the use of different reconstructions of the ice sheets and of the change in dust forcing. Additional (Tier 2) sensitivity experiments have been designed to quantify feedbacks associated with land-surface changes and aerosol loadings, and to isolate the role of individual forcings. Model analysis and evaluation will capitalize on the relative abundance of paleoenvironmental observations and quantitative climate reconstructions already available for the LGM.

The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments

Directory of Open Access Journals (Sweden)

M. Kageyama

2017-11-01

Full Text Available The Last Glacial Maximum (LGM, 21 000 years ago is one of the suite of paleoclimate simulations included in the current phase of the Coupled Model Intercomparison Project (CMIP6. It is an interval when insolation was similar to the present, but global ice volume was at a maximum, eustatic sea level was at or close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. The LGM has been a focus for the Paleoclimate Modelling Intercomparison Project (PMIP since its inception, and thus many of the problems that might be associated with simulating such a radically different climate are well documented. The LGM state provides an ideal case study for evaluating climate model performance because the changes in forcing and temperature between the LGM and pre-industrial are of the same order of magnitude as those projected for the end of the 21st century. Thus, the CMIP6 LGM experiment could provide additional information that can be used to constrain estimates of climate sensitivity. The design of the Tier 1 LGM experiment (lgm includes an assessment of uncertainties in boundary conditions, in particular through the use of different reconstructions of the ice sheets and of the change in dust forcing. Additional (Tier 2 sensitivity experiments have been designed to quantify feedbacks associated with land-surface changes and aerosol loadings, and to isolate the role of individual forcings. Model analysis and evaluation will capitalize on the relative abundance of paleoenvironmental observations and quantitative climate reconstructions already available for the LGM.

Acropora interbranch skeleton Sr/Ca ratios: Evaluation of a potential new high-resolution paleothermometer

Science.gov (United States)

Sadler, James; Nguyen, Ai D.; Leonard, Nicole D.; Webb, Gregory E.; Nothdurft, Luke D.

2016-04-01

The majority of coral geochemistry-based paleoclimate reconstructions in the Indo-Pacific are conducted on selectively cored colonies of massive Porites. This restriction to a single genus may make it difficult to amass the required paleoclimate data for studies that require deep reef coring techniques. Acropora, however, is a highly abundant coral genus in both modern and fossil reef systems and displays potential as a novel climate archive. Here we present a calibration study for Sr/Ca ratios recovered from interbranch skeleton in corymbose Acropora colonies from Heron Reef, southern Great Barrier Reef. Significant intercolony differences in absolute Sr/Ca ratios were normalized by producing anomaly plots of both coral geochemistry and instrumental water temperature records. Weighted linear regression of these anomalies from the lagoon and fore-reef slope provide a sensitivity of -0.05 mmol/mol °C-1, with a correlation coefficient (r2 = 0.65) comparable to those of genera currently used in paleoclimate reconstructions. Reconstructions of lagoon and reef slope mean seasonality in water temperature accurately identify the greater seasonal amplitude observed in the lagoon of Heron Reef. A longer calibration period is, however, required for reliable reconstructions of annual mean water temperatures.

Climate change and archaeology in Mesoamerica

Science.gov (United States)

Beach, Timothy

2016-03-01

I first encountered Mesoamerican paleoclimate in a graduate seminar taught by Herb Wright, Jr. in Geology at the University of Minnesota in 1984. Herb passed away in 2015 at 98 after decades of studying paleoclimate and many other aspects of Quaternary studies. In 1984 there were few Maya paleoclimate studies, and a Science article on Mayan Urbanism by Deevey et al. (1979) was still current. Mark Brenner was one of the authors of that piece and he has been constant over these decades, appearing again as a coauthor of two articles in this issue. Several recent articles have noted the expansion in Maya climate studies from the perspectives of Climate Science, to Paleotempestology, and to Archeology (Douglas et al., in this issue;Beach et al., 2015; Luzzadder-Beach et al., in press). This special issue grew out of the recognition of that explosion of studies and the need to bring some important current findings together in one issue. This special issue does that by incorporating new reviews and specific studies that help us refine the trends of climate change and the drivers of climate and their connections to what we know of human history and archeology in the region.

Building a New South Africa Volume 1 : Economic Policy | IDRC ...

International Development Research Centre (IDRC) Digital Library (Canada)

Couverture du livre Building a New South Africa Volume 1 : Economic Policy. Editor(s): ... Findings from an IDRC-supported program figure prominently at the annual conference of McGill's Institute for the Study of International Development. ... Special journal issue highlights IDRC-supported findings on women's paid work.

Rôle des femmes dans la vie politique, la contestation politique et la ...

International Development Research Centre (IDRC) Digital Library (Canada)

L'initiative Gouvernance démocratique, droits des femmes et égalité entre les .... un accord de coopération scientifique et technologique en appui aux projets de ... de l'Institut d'étude du développement international de l'Université McGill.

La dimension économique de la lutte antitabac dans les pays à ...

International Development Research Centre (IDRC) Digital Library (Canada)

Pratiques exemplaires en matière de taxation du tabac (élasticité de la demande, ... de l'Institut d'étude du développement international de l'Université McGill ... Abonnez-vous à notre bulletin pour recevoir les nouvelles du CRDI chaque mois.

Stable isotope analysis in ice core paleoclimatology

International Nuclear Information System (INIS)

Bertler, N.

2004-01-01

Ice cores are the most direct, continuous, and high resolution archive for Late Quaternary paleoclimate reconstruction. Ice cores from New Zealand and the Antarctic margin provide an excellent means of addressing the lack of longer-term climate observations in the Southern Hemisphere with near instrumental quality. Their study helps us to improve our understanding of regional patterns of climate behaviour in Antarctica and its influence on New Zealand, leading to more realistic regional climate models. Such models are needed to sensibly interpret current Antarctic and New Zealand climate variability and for the development of appropriate migration strategies for New Zealand. (author). 23 refs., 15 figs., 1 tab

Update of the androgen receptor gene mutations database.

Science.gov (United States)

Gottlieb, B; Beitel, L K; Lumbroso, R; Pinsky, L; Trifiro, M

1999-01-01

The current version of the androgen receptor (AR) gene mutations database is described. The total number of reported mutations has risen from 309 to 374 during the past year. We have expanded the database by adding information on AR-interacting proteins; and we have improved the database by identifying those mutation entries that have been updated. Mutations of unknown significance have now been reported in both the 5' and 3' untranslated regions of the AR gene, and in individuals who are somatic mosaics constitutionally. In addition, single nucleotide polymorphisms, including silent mutations, have been discovered in normal individuals and in individuals with male infertility. A mutation hotspot associated with prostatic cancer has been identified in exon 5. The database is available on the internet (http://www.mcgill.ca/androgendb/), from EMBL-European Bioinformatics Institute (ftp.ebi.ac.uk/pub/databases/androgen), or as a Macintosh FilemakerPro or Word file (MC33@musica.mcgill.ca). Copyright 1999 Wiley-Liss, Inc.

Promoting Cultural Awareness: A Faculty Development Workshop on Cultural Competency.

Science.gov (United States)

Carnevale, Franco A; Macdonald, Mary Ellen; Razack, Saleem; Steinert, Yvonne

2015-06-01

An interdisciplinary faculty development workshop on cultural competency (CC) was implemented and evaluated for the Faculty of Medicine at McGill University. It consisted of a 4-hour workshop and 2 follow-up sessions. A reflective practice framework was used. The project was evaluated using the Multicultural Assessment Questionnaire (MAQ), evaluation forms completed by participants, and detailed field notes taken during the sessions. The workshop was attended by 49 faculty members with diverse professional backgrounds. Statistically significant improvements were measured using the MAQ. On a scale of 1 to 5 (5 = very useful) on the evaluation form, the majority of participants (76.1%) gave the workshop a score of 4 or 5 for overall usefulness. A thematic analysis of field-note data highlighted participant responses to specific activities in the workshop. Participants expressed a need for faculty development initiatives on CC such as this one. Copyright© by Ingram School of Nursing, McGill University.

Growing Physics and Astronomy Public Outreach in Montreal

Science.gov (United States)

Simard, Gabrielle; Lepo, Kelly

2017-01-01

AstroMcGill was founded in 2011 by an enthusiastic group of undergraduate students, graduate students and post-doctoral fellows. It serves as the education and public outreach (EPO) branch of the astronomy group within the Physics Department at McGill University in Montreal, Quebec. Over the last five years, AstroMcGill has grown from organizing sporadic visits in a couple primary schools to running a successful inquiry-based outreach programme for grade 4-6 students, the McGill Space Explorers. During the same time span, the attendance at public AstroNight lectures ramped up from attracting a few dozen people to over 500 people each month. We will highlight the recent successes of the programme and our best guesses for the reasons behind this success. We will also discuss the challenges of working in a bilingual city as we juggle our majority anglophone volunteers, a mandatory french science curriculum for primary school children and the (somewhat) overlapping English- and French-speaking communities in the city.

A “Partnership” for the Professional Development of Librarian Researchers

Directory of Open Access Journals (Sweden)

Pamela Carson

2014-09-01

Full Text Available In this article the authors introduce the Librarians’ Research Partnership (LRP, founded in 2013, at McGill and Concordia University Libraries. The Partnership was inspired by the Canadian Association of Research Libraries’ Librarians’ Research Institute (CARL LRI which was attended by three of the authors in 2012 and is described here from the point of view of the participants. The authors touch upon the research culture at McGill and Concordia Libraries and discuss barriers and supports for research as prominent themes in the literature on the research role of Canadian academic librarians. The formation of the LRP and the eight subsequent meetings are explained in detail, as well as the factors that made the LRP a successful initiative between the two universities: physical proximity, similarity of working environments, and common organizational culture. The article also includes a discussion of how the LRP’s philosophy might diverge from that of the LRI.

A North American Hydroclimate Synthesis (NAHS) of the Common Era

Science.gov (United States)

Rodysill, Jessica R.; Anderson, Lesleigh; Cronin, Thomas M.; Jones, Miriam C.; Thompson, Robert S.; Wahl, David B.; Willard, Debra A.; Addison, Jason A.; Alder, Jay R.; Anderson, Katherine H.; Anderson, Lysanna; Barron, John A.; Bernhardt, Christopher E.; Hostetler, Steven W.; Kehrwald, Natalie M.; Khan, Nicole S.; Richey, Julie N.; Starratt, Scott W.; Strickland, Laura E.; Toomey, Michael R.; Treat, Claire C.; Wingard, G. Lynn

2018-03-01

This study presents a synthesis of century-scale hydroclimate variations in North America for the Common Era (last 2000 years) using new age models of previously published multiple proxy-based paleoclimate data. This North American Hydroclimate Synthesis (NAHS) examines regional hydroclimate patterns and related environmental indicators, including vegetation, lake water elevation, stream flow and runoff, cave drip rates, biological productivity, assemblages of living organisms, and salinity. Centennial-scale hydroclimate anomalies are obtained by iteratively sampling the proxy data on each of thousands of age model realizations and determining the fractions of possible time series indicating that the century-smoothed data was anomalously wet or dry relative to the 100 BCE to 1900 CE mean. Results suggest regionally asynchronous wet and dry periods over multidecadal to centennial timescales and frequent periods of extended regional drought. Most sites indicate drying during previously documented multicentennial periods of warmer Northern Hemisphere temperatures, particularly in the western U.S., central U.S., and Canada. Two widespread droughts were documented by the NAHS: from 50 BCE to 450 CE and from 800 to 1100 CE. Major hydroclimate reorganizations occurred out of sync with Northern Hemisphere temperature variations and widespread wet and dry anomalies occurred during both warm and cool periods. We present a broad assessment of paleoclimate relationships that highlights the potential influences of internal variability and external forcing and supports a prominent role for Pacific and Atlantic Ocean dynamics on century-scale continental hydroclimate.

A comparison of PMIP2 model simulations and the MARGO proxy reconstruction for tropical sea surface temperatures at last glacial maximum

Energy Technology Data Exchange (ETDEWEB)

Otto-Bliesner, Bette L.; Brady, E.C. [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States); Schneider, Ralph; Weinelt, M. [Christian-Albrechts Universitaet, Institut fuer Geowissenschaften, Kiel (Germany); Kucera, M. [Eberhard-Karls Universitaet Tuebingen, Institut fuer Geowissenschaften, Tuebingen (Germany); Abe-Ouchi, A. [The University of Tokyo, Center for Climate System Research, Kashiwa (Japan); Bard, E. [CEREGE, College de France, CNRS, Universite Aix-Marseille, Aix-en-Provence (France); Braconnot, P.; Kageyama, M.; Marti, O.; Waelbroeck, C. [Unite mixte CEA-CNRS-UVSQ, Laboratoire des Sciences du Climat et de l' Environnement, Gif-sur-Yvette Cedex (France); Crucifix, M. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Hewitt, C.D. [Met Office Hadley Centre, Exeter (United Kingdom); Paul, A. [Bremen University, Department of Geosciences, Bremen (Germany); Rosell-Mele, A. [Universitat Autonoma de Barcelona, ICREA and Institut de Ciencia i Tecnologia Ambientals, Barcelona (Spain); Weber, S.L. [Royal Netherlands Meteorological Institute (KNMI), De Bilt (Netherlands); Yu, Y. [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China)

2009-05-15

Results from multiple model simulations are used to understand the tropical sea surface temperature (SST) response to the reduced greenhouse gas concentrations and large continental ice sheets of the last glacial maximum (LGM). We present LGM simulations from the Paleoclimate Modelling Intercomparison Project, Phase 2 (PMIP2) and compare these simulations to proxy data collated and harmonized within the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface Project (MARGO). Five atmosphere-ocean coupled climate models (AOGCMs) and one coupled model of intermediate complexity have PMIP2 ocean results available for LGM. The models give a range of tropical (defined for this paper as 15 S-15 N) SST cooling of 1.0-2.4 C, comparable to the MARGO estimate of annual cooling of 1.7{+-}1 C. The models simulate greater SST cooling in the tropical Atlantic than tropical Pacific, but interbasin and intrabasin variations of cooling are much smaller than those found in the MARGO reconstruction. The simulated tropical coolings are relatively insensitive to season, a feature also present in the MARGO transferred-based estimates calculated from planktonic foraminiferal assemblages for the Indian and Pacific Oceans. These assemblages indicate seasonality in cooling in the Atlantic basin, with greater cooling in northern summer than northern winter, not captured by the model simulations. Biases in the simulations of the tropical upwelling and thermocline found in the preindustrial control simulations remain for the LGM simulations and are partly responsible for the more homogeneous spatial and temporal LGM tropical cooling simulated by the models. The PMIP2 LGM simulations give estimates for the climate sensitivity parameter of 0.67 -0.83 C per Wm{sup -2}, which translates to equilibrium climate sensitivity for doubling of atmospheric CO{sub 2} of 2.6-3.1 C. (orig.)

Using a Global Climate Model in an On-line Climate Change Course

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Randle, D. E.; Chandler, M. A.; Sohl, L. E.

2012-12-01

Seminars on Science: Climate Change is an on-line, graduate-level teacher professional development course offered by the American Museum of Natural History. It is an intensive 6-week course covering a broad range of global climate topics, from the fundamentals of the climate system, to the causes of climate change, the role of paleoclimate investigations, and a discussion of potential consequences and risks. The instructional method blends essays, videos, textbooks, and linked websites, with required participation in electronic discussion forums that are moderated by an experienced educator and a course scientist. Most weeks include additional assignments. Three of these assignments employ computer models, including two weeks spent working with a full-fledged 3D global climate model (GCM). The global climate modeling environment is supplied through a partnership with Columbia University's Educational Global Climate Modeling Project (EdGCM). The objective is to have participants gain hands-on experience with one of the most important, yet misunderstood, aspects of climate change research. Participants in the course are supplied with a USB drive that includes installers for the software and sample data. The EdGCM software includes a version of NASA's global climate model fitted with a graphical user interface and pre-loaded with several climate change simulations. Step-by-step assignments and video tutorials help walk people through these challenging exercises and the course incorporates a special assignment discussion forum to help with technical problems and questions about the NASA GCM. There are several takeaways from our first year and a half of offering this course, which has become one of the most popular out of the twelve courses offered by the Museum. Participants report a high level of satisfaction in using EdGCM. Some report frustration at the initial steps, but overwhelmingly claim that the assignments are worth the effort. Many of the difficulties that

Nutrition and food security in rural China: An assessment of school ...

International Development Research Centre (IDRC) Digital Library (Canada)

The school feeding system in China provides 180 to 200 days of meals a year to ... to their health and nutritional status, school attendance, and educational outcomes. ... IDRC congratulates first cohort of Women in Climate Change Science Fellows ... conference of McGill's Institute for the Study of International Development.

76 FR 17840 - Notice of Intent To License Government-Owned Inventions; Intent To License Exclusively

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2011-03-31

... DEPARTMENT OF DEFENSE Department of the Army Notice of Intent To License Government-Owned Inventions; Intent To License Exclusively AGENCY: Department of the Army, DoD. ACTION: Notice. SUMMARY: The... McGill telephone: 410-436-8467, [email protected]us.army.mil , U.S. Army Edgewood Chemical Biological Center...

Donner aux filles et aux femmes le pouvoir de décider | CRDI ...

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éclampsie et d'hypertension artérielle, et peuvent également entraîner un faible poids à la naissance et des naissances prématurées. La Federation of Muslim Women's Association of Nigeria et l'Université McGill à Montréal, ...

Prospera Digital Phase II: Financial inclusion for low-income women ...

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Prospera Digital Phase II: Financial inclusion for low-income women in Mexico ... a research network in Latin America, to identify barriers and opportunities to scale up ... Call for new OWSD Fellowships for Early Career Women Scientists now open ... conference of McGill's Institute for the Study of International Development.

Trends in Adults Receiving a Recommendation for Exercise or Other Physical Activity from a Physician or Other Health ...

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... U.S. national physical activity plan. J Phys Act Health 6(suppl 2):S211–9. 2009. Weidinger KA, Lovegreen SL, Elliott MB, Hagood L, Haire-Joshu D, Mcgill JB, Brownson RC. How to make exercise counseling more effective: Lessons from rural America. J Fam Pract 57( ...

A Poster Assignment Connects Information Literacy and Writing Skills

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Waters, Natalie

2015-01-01

This paper describes the implementation of a poster assignment in a writing and information literacy course required for undergraduate Life Sciences and Environmental Biology majors with the Faculty of Agricultural and Environmental Sciences at McGill University. The assignment was introduced in response to weaknesses identified through course…

Évolution démographique asymétrique et gouvernance financière ...

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Brazil, South America, China, Far East Asia, India, South Africa, North of Sahara, South of Sahara, North and Central America, Central Asia, South Asia ... the annual conference of McGill's Institute for the Study of International Development. ... in India, including heat stress, water management, and climate-related migration.

Archaeology: A Guide to Reference Sources.

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Morrison, Doreen, Comp.

This bibliographic guide lists reference sources available at McGill University for research in prehistory and non-classical archaeology. No exclusively biographical sources have been included, but many of the encyclopedias and handbooks contain biographical information and are annotated accordingly. Titles are listed in the following categories:…

Take a Paws: Fostering Student Wellness with a Therapy Dog Program at Your University Library

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Lannon, Amber; Harrison, Pamela

2015-01-01

Therapy dogs are trained and socialized to provide comfort to individuals who are ill or experiencing stress. The following article explores therapy dog outreach programs in academic libraries by describing a successful venture at McGill University Library. Background, planning advice, assessment results, and recommendations are presented with an…

Application des TIC à l'atténuation des effets des catastrophes dans ...

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L'Amérique centrale est souvent aux prises avec des inondations et des ... (SIG) et de traitement des images, afin de cartographier les dangers et de modéliser les ... de l'Institut d'étude du développement international de l'Université McGill.

Isotope effects in the evaporation of water: a status report of the Craig-Gordon model.

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Horita, Juske; Rozanski, Kazimierz; Cohen, Shabtai

2008-03-01

The Craig-Gordon model (C-G model) [H. Craig, L.I. Gordon. Deuterium and oxygen 18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperatures, E. Tongiorgi (Ed.), pp. 9-130, Laboratorio di Geologia Nucleare, Pisa (1965).] has been synonymous with the isotope effects associated with the evaporation of water from surface waters, soils, and vegetations, which in turn constitutes a critical component of the global water cycle. On the occasion of the four decades of its successful applications to isotope geochemistry and hydrology, an attempt is made to: (a) examine its physical background within the framework of modern evaporation models, (b) evaluate our current knowledge of the environmental parameters of the C-G model, and (c) comment on a general strategy for the use of these parameters in field applications. Despite its simplistic representation of evaporation processes at the water-air interface, the C-G model appears to be adequate to provide the isotopic composition of the evaporation flux. This is largely due to its nature for representing isotopic compositions (a ratio of two fluxes of different isotopic water molecules) under the same environmental conditions. Among many environmental parameters that are included in the C-G model, accurate description and calculations are still problematic of the kinetic isotope effects that occur in a diffusion-dominated thin layer of air next to the water-air interface. In field applications, it is of importance to accurately evaluate several environmental parameters, particularly the relative humidity and isotopic compositions of the 'free-atmosphere', for a system under investigation over a given time-scale of interest (e.g., hourly to daily to seasonally). With a growing interest in the studies of water cycles of different spatial and temporal scales, including paleoclimate and water resource studies, the importance and utility of the C-G model is also likely to

Monthly paleostreamflow reconstruction from annual tree-ring chronologies

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Stagge, J. H.; Rosenberg, D. E.; DeRose, R. J.; Rittenour, T. M.

2018-02-01

Paleoclimate reconstructions are increasingly used to characterize annual climate variability prior to the instrumental record, to improve estimates of climate extremes, and to provide a baseline for climate-change projections. To date, paleoclimate records have seen limited engineering use to estimate hydrologic risks because water systems models and managers usually require streamflow input at the monthly scale. This study explores the hypothesis that monthly streamflows can be adequately modeled by statistically decomposing annual flow reconstructions. To test this hypothesis, a multiple linear regression model for monthly streamflow reconstruction is presented that expands the set of predictors to include annual streamflow reconstructions, reconstructions of global circulation, and potential differences among regional tree-ring chronologies related to tree species and geographic location. This approach is used to reconstruct 600 years of monthly streamflows at two sites on the Bear and Logan rivers in northern Utah. Nash-Sutcliffe Efficiencies remain above zero (0.26-0.60) for all months except April and Pearson's correlation coefficients (R) are 0.94 and 0.88 for the Bear and Logan rivers, respectively, confirming that the model can adequately reproduce monthly flows during the reference period (10/1942 to 9/2015). Incorporating a flexible transition between the previous and concurrent annual reconstructed flows was the most important factor for model skill. Expanding the model to include global climate indices and regional tree-ring chronologies produced smaller, but still significant improvements in model fit. The model presented here is the only approach currently available to reconstruct monthly streamflows directly from tree-ring chronologies and climate reconstructions, rather than using resampling of the observed record. With reasonable estimates of monthly flow that extend back in time many centuries, water managers can challenge systems models with a

The Urbino Summer School in Paleoclimatology: Investing in the future of paleoclimatology

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Schellenberg, S. A.; Galeotti, S.; Brinkhuis, H.; Leckie, R. M.

2010-12-01

of paleoclimate modeling and proxy data. The third week also includes the “Cioppino” conference comprised of lectures by experts from various fields that presenting “new and exciting ideas for digestion.” The course concludes with a series of lectures, discussion, and student presentations examining the relevance of paleoclimate to understanding modern climate dynamics and anthropogenic impacts. Student costs are increasingly being reduced per capita through governmental/institutional underwriting and individually through competitive awards (e.g., recent NSF USSP scholarships). Based on student and faculty evaluations, the current USSP structure appears largely optimized for our initial goal of promoting the integration of paleoclimate proxy data and modeling. Current planning efforts focus on strengthening course connections to Anthropocene issues and managing the large number of international faculty who donate their time and energy as an investment in the future of paleoclimatology.

75 FR 21353 - Notice of Determinations Regarding Eligibility To Apply for Worker Adjustment Assistance

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2010-04-23

..., AR, June 12, 2008 TA-W-71,409: Emerson Power Transmission, McGill Manufacturing Division, Valparaiso... Resource, Rochester, NY, August 1, 2008 TA-W-72,343: Chamberlain Wireless Products Group, Inc., Volt... TA-W-72,606: American Food and Vending, Spring Hill, TN TA-W-72,634: Cimarron Energy, Inc., Marlow...

Optimizing ChIP-seq peak detectors using visual labels and supervised machine learning.

Science.gov (United States)

Hocking, Toby Dylan; Goerner-Potvin, Patricia; Morin, Andreanne; Shao, Xiaojian; Pastinen, Tomi; Bourque, Guillaume

2017-02-15

Many peak detection algorithms have been proposed for ChIP-seq data analysis, but it is not obvious which algorithm and what parameters are optimal for any given dataset. In contrast, regions with and without obvious peaks can be easily labeled by visual inspection of aligned read counts in a genome browser. We propose a supervised machine learning approach for ChIP-seq data analysis, using labels that encode qualitative judgments about which genomic regions contain or do not contain peaks. The main idea is to manually label a small subset of the genome, and then learn a model that makes consistent peak predictions on the rest of the genome. We created 7 new histone mark datasets with 12 826 visually determined labels, and analyzed 3 existing transcription factor datasets. We observed that default peak detection parameters yield high false positive rates, which can be reduced by learning parameters using a relatively small training set of labeled data from the same experiment type. We also observed that labels from different people are highly consistent. Overall, these data indicate that our supervised labeling method is useful for quantitatively training and testing peak detection algorithms. Labeled histone mark data http://cbio.ensmp.fr/~thocking/chip-seq-chunk-db/ , R package to compute the label error of predicted peaks https://github.com/tdhock/PeakError. toby.hocking@mail.mcgill.ca or guil.bourque@mcgill.ca. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

The Influence of Sampling Density on Bayesian Age-Depth Models and Paleoclimatic Reconstructions - Lessons Learned from Lake Titicaca - Bolivia/Peru

Science.gov (United States)

Salenbien, W.; Baker, P. A.; Fritz, S. C.; Guedron, S.

2014-12-01

Lake Titicaca is one of the most important archives of paleoclimate in tropical South America, and prior studies have elucidated patterns of climate variation at varied temporal scales over the past 0.5 Ma. Yet, slow sediment accumulation rates in the main deeper basin of the lake have precluded analysis of the lake's most recent history at high resolution. To obtain a paleoclimate record of the last few millennia at multi-decadal resolution, we obtained five short cores, ranging from 139 to 181 cm in length, from the shallower Wiñaymarka sub-basin of of Lake Titicaca, where sedimentation rates are higher than in the lake's main basin. Selected cores have been analyzed for their geochemical signature by scanning XRF, diatom stratigraphy, sedimentology, and for 14C age dating. A total of 72 samples were 14C-dated using a Gas Ion Source automated high-throughput method for carbonate samples (mainly Littoridina sp. and Taphius montanus gastropod shells) at NOSAMS (Woods Hole Oceanographic Institute) with an analytical precision higher than 2%. The method has lower analytical precision compared with traditional AMS radiocarbon dating, but the lower cost enables analysis of a larger number of samples, and the error associated with the lower precision is relatively small for younger samples (< ~8,000 years). A 172-cm-long core was divided into centimeter long sections, and 47 14C dates were obtained from 1-cm intervals, averaging one date every 3-4 cm. The other cores were radiocarbon dated with a sparser sampling density that focused on visual unconformities and shell beds. The high-resolution radiocarbon analysis reveals complex sedimentation patterns in visually continuous sections, with abundant indicators of bioturbated or reworked sediments and periods of very rapid sediment accumulation. These features are not evident in the sparser sampling strategy but have significant implications for reconstructing past lake level and paleoclimatic history.

Trent Hoole | IDRC - International Development Research Centre

International Development Research Centre (IDRC) Digital Library (Canada)

Trent Hoole is Corporate Secretary and General Counsel. From 2002-2012, he served in progressive senior legal counsel roles at IDRC. Hoole articled with a prominent litigation law firm in Ottawa. He holds an LLB from the University of Ottawa, and a Bachelor of Arts, joint honours, from McGill University.​

Reportages sur les violations des droits de la personne en vue de ...

International Development Research Centre (IDRC) Digital Library (Canada)

Malgré la prévalence des violations des droits de la personne et du droit ... de débat public à ce sujet et la réticence des responsables des politiques et des politiciens ... de l'Institut d'étude du développement international de l'Université McGill.

Kenya | Page 72 | IDRC - International Development Research Centre

International Development Research Centre (IDRC) Digital Library (Canada)

Improving the quality of HIV/AIDS nursing care. Supporting the ... The state of climate change adaptation globally is not well understood due to a dearth of organized approaches for tracking adaptation efforts, James Ford of Canada's McGill University told experts at a global conference in Paris. He made the remarks during ...

Jean Lebel | IDRC - International Development Research Centre

International Development Research Centre (IDRC) Digital Library (Canada)

Jean previously served as Vice-President, Program and Partnership Branch, overseeing all IDRC programming, as well as Director, Agriculture and Environment. He holds a PhD in environmental sciences from l'Université du Québec à Montréal and an MScA in occupational health sciences from McGill University.

Denis Trudeau | IDRC - International Development Research Centre

International Development Research Centre (IDRC) Digital Library (Canada)

... Management and Technology. Before joining IDRC, he worked as part of the global team of Sanmina Corporation. Prior to that role he was Director of IT Solutions at the University of Ottawa, BlackBerry, Alcatel-Lucent, and Nortel. Denis has a bachelor of electrical engineering with a computer option from McGill University.

Rapid Late Holocene glacier fluctuations reconstructed from South Georgia lake sediments using novel analytical and numerical techniques

Science.gov (United States)

van der Bilt, Willem; Bakke, Jostein; Werner, Johannes; Paasche, Øyvind; Rosqvist, Gunhild

2016-04-01

The collapse of ice shelves, rapidly retreating glaciers and a dramatic recent temperature increase show that Southern Ocean climate is rapidly shifting. Also, instrumental and modelling data demonstrate transient interactions between oceanic and atmospheric forcings as well as climatic teleconnections with lower-latitude regions. Yet beyond the instrumental period, a lack of proxy climate timeseries impedes our understanding of Southern Ocean climate. Also, available records often lack the resolution and chronological control required to resolve rapid climate shifts like those observed at present. Alpine glaciers are found on most Southern Ocean islands and quickly respond to shifts in climate through changes in mass balance. Attendant changes in glacier size drive variations in the production of rock flour, the suspended product of glacial erosion. This climate response may be captured by downstream distal glacier-fed lakes, continuously recording glacier history. Sediment records from such lakes are considered prime sources for paleoclimate reconstructions. Here, we present the first reconstruction of Late Holocene glacier variability from the island of South Georgia. Using a toolbox of advanced physical, geochemical (XRF) and magnetic proxies, in combination with state-of-the-art numerical techniques, we fingerprinted a glacier signal from glacier-fed lake sediments. This lacustrine sediment signal was subsequently calibrated against mapped glacier extent with the help of geomorphological moraine evidence and remote sensing techniques. The outlined approach enabled us to robustly resolve variations of a complex glacier at sub-centennial timescales, while constraining the sedimentological imprint of other geomorphic catchment processes. From a paleoclimate perspective, our reconstruction reveals a dynamic Late Holocene climate, modulated by long-term shifts in regional circulation patterns. We also find evidence for rapid medieval glacier retreat as well as a

Towards a new paleotemperature proxy from reef coral occurrences.

Science.gov (United States)

Lauchstedt, Andreas; Pandolfi, John M; Kiessling, Wolfgang

2017-09-05

Global mean temperature is thought to have exceeded that of today during the last interglacial episode (LIG, ~ 125,000 yrs b.p.) but robust paleoclimate data are still rare in low latitudes. Occurrence data of tropical reef corals may provide new proxies of low latitude sea-surface temperatures. Using modern reef coral distributions we developed a geographically explicit model of sea surface temperatures. Applying this model to coral occurrence data of the LIG provides a latitudinal U-shaped pattern of temperature anomalies with cooler than modern temperatures around the equator and warmer subtropical climes. Our results agree with previously published estimates of LIG temperatures and suggest a poleward broadening of the habitable zone for reef corals during the LIG.

Paleoclimates of Amazonia: An ice-age view

NARCIS (Netherlands)

Bush, M.B.; De Oliveira, P.E.; Raczka, M.F.; Gosling, W.D.; Mayle, F.E.; McMichael, C.H.; Urrego, D.H.; de Souza Carvalho, I.; Garcia, M.J.; Cunha Lana, C.; Strohschoen Jr., O.

2014-01-01

A growing body of evidence points to climatic complexity during the Ice-Ages. Amazonia does not respond uniformly to modern climatic forcing, and the same was true of the past. Although some climatic forcings were probably expressed everywhere, they were manifested differently. Consequently, climate

A human model of inflammatory cardio-metabolic dysfunction; a double blind placebo-controlled crossover trial

Directory of Open Access Journals (Sweden)

Mehta Nehal N

2012-06-01

Full Text Available Abstract Background Chronic inflammation may contribute to insulin resistance (IR, metabolic syndrome and atherosclerosis although evidence of causality is lacking in humans. We hypothesized that very low-dose experimental endotoxemia would induce adipose tissue inflammation and systemic IR during a low-grade but asymptomatic inflammatory response and thus provide an experimental model for future tests of pharmacologic and genomic modulation of cardio-metabolic traits in humans. Methods Ten healthy, human volunteers (50% male, 90% Caucasian, mean age 22.7 ± 3.8 were randomized in a double-masked, placebo-controlled, crossover study to separate 36-hour inpatient visits (placebo versus intravenous-LPS 0.6 ng/kg. We measured clinical symptoms via the McGill pain questionnaire and serial vital signs. Plasma and serum were collected for measurement of cytokines, C-reactive protein, insulin and glucose, serial whole blood & subcutaneous adipose tissue mRNA expression were measured by real-time PCR. HOMA-IR, a well-validated measure of IR was calculated to estimate insulin resistance, and frequently sampled intravenous glucose tolerance testing (FSIGTT was performed to confirm an insulin resistant state. We performed ANOVA and within subject ANOVA to understand the differences in cytokines, adipose tissue inflammation and IR before and after LPS or placebo. Results There was no significant difference between placebo and LPS in clinical responses of symptom scores, body temperature or heart rate. However, low-dose endotoxemia induced a rapid and transient 25-fold induction of plasma TNF-alpha and 100-fold increase in plasma IL-6 (Figure 1B (p p p = 0.01 increased with MCP-1 (peak 10-fold, F = 5.6, p p p p  Conclusions We present a low dose human endotoxemia model of inflammation which induces adipose tissue inflammation and systemic insulin resistance in the absence of overt clinical response. Such a model has the potential

EDITORIAL: International Workshop on Monte Carlo Techniques in Radiotherapy Delivery and Verification

Science.gov (United States)

Verhaegen, Frank; Seuntjens, Jan

2008-03-01

Monte Carlo particle transport techniques offer exciting tools for radiotherapy research, where they play an increasingly important role. Topics of research related to clinical applications range from treatment planning, motion and registration studies, brachytherapy, verification imaging and dosimetry. The International Workshop on Monte Carlo Techniques in Radiotherapy Delivery and Verification took place in a hotel in Montreal in French Canada, from 29 May-1 June 2007, and was the third workshop to be held on a related topic, which now seems to have become a tri-annual event. About one hundred workers from many different countries participated in the four-day meeting. Seventeen experts in the field were invited to review topics and present their latest work. About half of the audience was made up by young graduate students. In a very full program, 57 papers were presented and 10 posters were on display during most of the meeting. On the evening of the third day a boat trip around the island of Montreal allowed participants to enjoy the city views, and to sample the local cuisine. The topics covered at the workshop included the latest developments in the most popular Monte Carlo transport algorithms, fast Monte Carlo, statistical issues, source modeling, MC treatment planning, modeling of imaging devices for treatment verification, registration and deformation of images and a sizeable number of contributions on brachytherapy. In this volume you will find 27 short papers resulting from the workshop on a variety of topics, some of them on very new stuff such as graphics processing units for fast computing, PET modeling, dual-energy CT, calculations in dynamic phantoms, tomotherapy devices, . . . . We acknowledge the financial support of the National Cancer Institute of Canada, the Institute of Cancer Research of the Canadian Institutes of Health Research, the Association Québécoise des Physicien(ne)s Médicaux Clinique, the Institute of Physics, and Medical

Climate Reconstructions

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Paleoclimatology Program archives reconstructions of past climatic conditions derived from paleoclimate proxies, in addition to the Program's large holdings...

Pliocene climate

Science.gov (United States)

Dowsett, Harry J.; Caballero-Gill, R. P.

2010-01-01

The Pliocene Epoch, 5.3 Ma to 1.8 Ma, was a time when paleoclimate conditions ranged from very warm, equable climates (on a global scale), rhythmically varying every 40,000 years, to high-amplitude glacial-interglacial cycles that led to the “Ice Ages” of the Pleistocene. Evidence for paleoclimate conditions comes from fossils, geochemical data, and the integration of these data with sophisticated numerical models. The Pliocene exhibited a range in atmospheric CO2 concentrations with highs estimated to be at most ~425 ppm in the early Pliocene followed by overall decrease toward preindustrial levels by the close of the Pliocene Epoch (Pagani et al. 2010). Sea levels were estimated to be 25m higher than present day and the size and position of ice sheets in Greenland and Antarctica were decidedly different from today. On the other hand, by the mid-Pliocene, the majority of fauna and flora as well as continental configurations were basically the same as today. Man’s ability to adapt to or mitigate the effects of future climate require a deep understanding of the rates and magnitude of future climate change on an ever finer scale. Since conditions projected for the end of this century are not in the human experience, we depend upon a combination of numerical climate models and comparison to analogous conditions in the geologic past. The Pliocene contains what might be the closest analog to climate conditions expected in the near future, and therefore understanding the Pliocene is not only of academic interest but essential for human adaptation.

Partnership Bound: Using MAPS with Transitioning Students and Families from All Backgrounds

Science.gov (United States)

Haines, Shana J.; Francis, Grace L.; Shepherd, Katharine G.; Ziegler, Meg; Mabika, Goma

2018-01-01

The McGill Action Planning System (also referred to as Making Action Plans or MAPS) is a supportive, strengths-based process that enables teams to understand each other and work together to support students in achieving their dreams. This process can work very well with all transitioning students with disabilities and their families, including…

Partenariat Canada-Caraïbes sur l'adaptation des collectivités aux ...

International Development Research Centre (IDRC) Digital Library (Canada)

Mettre en place des réseaux scientifiques et professionnels qui font progresser la ... climatiques en consolidant les structures institutionnelles et de gouvernance. ... ont conclu un accord de coopération scientifique et technologique en appui aux ... de l'Institut d'étude du développement international de l'Université McGill.

Comprendre l'impunité : le droit à la vérité, à la justice et à des ...

International Development Research Centre (IDRC) Digital Library (Canada)

Comprendre l'impunité : le droit à la vérité, à la justice et à des réparations ... nom de la souveraineté, de la sécurité, de l'ordre public et de la lutte contre le terrorisme ... conference of McGill's Institute for the Study of International Development.

A Reflection on Aging: A Portfolio of Change in Attitudes toward Geriatric Patients during a Clerkship Rotation

Science.gov (United States)

Del Duca, Danny; Duque, Gustavo

2006-01-01

The process of students' evaluation in medical schools has changed from a tutor-led evaluation system based on students' performance to a student-based evaluation that involves self-reflection and their level of change in skills and attitudes. At the McGill University Division of Geriatric Medicine, we developed an innovative system of evaluation…

Kenya | Page 59 | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

In the fields of sub-Saharan Africa, Alan Watson and McGill University's Weed Research Group are battling devastating parasites — naturally. Something big was happening in these agricultural fields of Mali, anyone could see that. Two plots of sorghum, a staple crop across sub-Saharan Africa, reached up to the clear blue ...

Comparing modeled and observed changes in mineral dust transport and deposition to Antarctica between the Last Glacial Maximum and current climates

Energy Technology Data Exchange (ETDEWEB)

Albani, Samuel [University of Siena, Graduate School in Polar Sciences, Siena (Italy); University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Mahowald, Natalie M. [Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Delmonte, Barbara; Maggi, Valter [University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Winckler, Gisela [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Columbia University, Department of Earth and Environmental Sciences, New York, NY (United States)

2012-05-15

Mineral dust aerosols represent an active component of the Earth's climate system, by interacting with radiation directly, and by modifying clouds and biogeochemistry. Mineral dust from polar ice cores over the last million years can be used as paleoclimate proxy, and provide unique information about climate variability, as changes in dust deposition at the core sites can be due to changes in sources, transport and/or deposition locally. Here we present results from a study based on climate model simulations using the Community Climate System Model. The focus of this work is to analyze simulated differences in the dust concentration, size distribution and sources in current climate conditions and during the Last Glacial Maximum at specific ice core locations in Antarctica, and compare with available paleodata. Model results suggest that South America is the most important source for dust deposited in Antarctica in current climate, but Australia is also a major contributor and there is spatial variability in the relative importance of the major dust sources. During the Last Glacial Maximum the dominant source in the model was South America, because of the increased activity of glaciogenic dust sources in Southern Patagonia-Tierra del Fuego and the Southernmost Pampas regions, as well as an increase in transport efficiency southward. Dust emitted from the Southern Hemisphere dust source areas usually follow zonal patterns, but southward flow towards Antarctica is located in specific areas characterized by southward displacement of air masses. Observations and model results consistently suggest a spatially variable shift in dust particle sizes. This is due to a combination of relatively reduced en route wet removal favouring a generalized shift towards smaller particles, and on the other hand to an enhanced relative contribution of dry coarse particle deposition in the Last Glacial Maximum. (orig.)

Reconciling atmospheric temperatures in the early Archean

DEFF Research Database (Denmark)

Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif

rock record. The goal of this study is to compile and reconcile Archean geologic and geochemical features that are in some way controlled by surface temperature and/or atmospheric composition, so that at the very least paleoclimate models can be checked by physical limits. Data used to this end include...... weathering on climate). Selective alteration of δD in Isua rocks to values of -130 to -100‰ post-dates ca. 3.55Ga Ameralik dikes, but may be associated with a poorly defined 2.6-2.8Ga metamorphic event that is coincident with the amalgamation of the “Kenorland supercontinent.”...

Climate, greenhouse effect, energy

International Nuclear Information System (INIS)

Henriksen, Thormod; Kanestroem, Ingolf

2001-01-01

The book has sections on the sun as energy source, the earth climate and it's changes and factors influencing this, the greenhouse effect on earth and other planets, greenhouse gases and aerosols and their properties and importance, historic climate and paleoclimate, climatic models and their uses and limitations, future climate, consequences of climatic changes, uncertainties regarding the climate and measures for reducing the greenhouse effect. Finally there are sections on energy and energy resources, the use, sources such as fossil fuels, nuclear power, renewable resources, heat pumps, energy storage and environmental aspects and the earth magnetic field is briefly surveyed

Paleoclimate determines diversification patterns in the fossorial snake family Uropeltidae Cuvier, 1829.

Science.gov (United States)

Cyriac, Vivek Philip; Kodandaramaiah, Ullasa

2017-11-01

Understanding how and why diversification rates vary across evolutionary time is central to understanding how biodiversity is generated and maintained. Recent mathematical models that allow estimation of diversification rates across time from reconstructed phylogenies have enabled us to make inferences on how biodiversity copes with environmental change. Here, we explore patterns of temporal diversification in Uropeltidae, a diverse fossorial snake family. We generate a time-calibrated phylogenetic hypothesis for Uropeltidae and show a significant correlation between diversification rate and paleotemperature during the Cenozoic. We show that the temporal diversification pattern of this group is punctuated by one rate shift event with a decrease in diversification and turnover rate between ca. 11Ma to present, but there is no strong support for mass extinction events. The analysis indicates higher turnover during periods of drastic climatic fluctuations and reduced diversification rates associated with contraction and fragmentation of forest habitats during the late Miocene. Our study highlights the influence of environmental fluctuations on diversification rates in fossorial taxa such as uropeltids, and raises conservation concerns related to present rate of climate change. Copyright © 2017 Elsevier Inc. All rights reserved.

High resolution HH-XRF scanning and XRD modelling as a tool in sedimentological analysis - A case study from the Enreca-3 core, Bach Long Vi Island, Vietnam

Science.gov (United States)

Rizzi, Malgorzata; Hemmingsen Schovsbo, Niels; Korte, Christoph; Bryld Wessel Fyhn, Michael

2017-04-01

To improve the understanding and interpretation of the depositional environment of a late Oligocene lacustrine organic rich oil-prone source rock succession, 2464 hand held (HH)-XRF measurements were made systematically on the 500 m long, continuous core from the fully cored Enreca-3 well. This core, drilled on the remote Bach Long Vi Island, northern Gulf of Tonkin, offshore Vietnam, represents a deep lake succession alternating between lacustrine pelagic dominated sediments interrupted by hyperpycnal turbidites, high density turbidites and debris flows [1, 2]. From a combined HH-XRF-XRD data set, multivariate data analysis and regression models are used to type the rock and to predict the XRD mineral composition based on HH-XRF composition. The rock types and the modelled mineral composition highlight the geochemical variations of the sediment and allows for direct comparison with sedimentological processes and facies changes. The modeling also depicts the cyclic alteration of rock types that are present on many different scales ranging from centimeters to hundreds of meters [1, 2]. The sedimentological and geochemical variations observed throughout the cored section reflects fluctuating paleoclimate, tectonism and hinterland condition controlling the depositional setting, which may provide a deeper understanding of the deposition of this and similar Paleogene syn-rift succession in the South China Sea region. It allows furthermore the development of a more generalized depositional model relevant for other deep-lacustrine syn-rift basins. [1] Petersen et al. (2014) Journal of Petroleum Geology, 37: 373-389. [2] Hovikoski et al. (2016) Journal of Sedimentary Research, 86(8): 982-1007.

Western Regional Conference on Testing Problems (7th, Los Angeles, California, March 14, 1958). Testing for the Discovery and Development of Human Talent.

Science.gov (United States)

Educational Testing Service, Los Angeles, CA.

At the seventh Western Regional Conference on Testing Problems, the following speeches were given: (1) "A Guidance Person's Approach to Testing for the Discovery and Development of Human Talent" by Frances D. McGill; (2) "The Instructional Uses of Measurement in the Discovery and Development of Human Talent" by Roy P. Wahle; (3) "New Frontiers of…

Argent mobile et développement local | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

De nouvelles applications financières accessibles depuis un appareil mobile (le concept d'argent mobile) réduisent les coûts d'exploitation et favorisent l'accès des pauvres au système financier en offrant des moyens faciles, efficaces, sûrs et ... IDRC “unpacks women's empowerment” at McGill University Conference.

Changes in the Global Hydrological Cycle: Lessons from Modeling Lake Levels at the Last Glacial Maximum

Science.gov (United States)

Lowry, D. P.; Morrill, C.

2011-12-01

Geologic evidence shows that lake levels in currently arid regions were higher and lakes in currently wet regions were lower during the Last Glacial Maximum (LGM). Current hypotheses used to explain these lake level changes include the thermodynamic hypothesis, in which decreased tropospheric water vapor coupled with patterns of convergence and divergence caused dry areas to become more wet and vice versa, the dynamic hypothesis, in which shifts in the jet stream and Inter-Tropical Convergence Zone (ITCZ) altered precipitation patterns, and the evaporation hypothesis, in which lake expansions are attributed to reduced evaporation in a colder climate. This modeling study uses the output of four climate models participating in phase 2 of the Paleoclimate Modeling Intercomparison Project (PMIP2) as input into a lake energy-balance model, in order to test the accuracy of the models and understand the causes of lake level changes. We model five lakes which include the Great Basin lakes, USA; Lake Petén Itzá, Guatemala; Lake Caçó, northern Brazil; Lake Tauca (Titicaca), Bolivia and Peru; and Lake Cari-Laufquen, Argentina. These lakes create a transect through the drylands of North America through the tropics and to the drylands of South America. The models accurately recreate LGM conditions in 14 out of 20 simulations, with the Great Basin lakes being the most robust and Lake Caçó being the least robust, due to model biases in portraying the ITCZ over South America. An analysis of the atmospheric moisture budget from one of the climate models shows that thermodynamic processes contribute most significantly to precipitation changes over the Great Basin, while dynamic processes are most significant for the other lakes. Lake Cari-Laufquen shows a lake expansion that is most likely attributed to reduced evaporation rather than changes in regional precipitation, suggesting that lake levels alone may not be the best indicator of how much precipitation this region

2013 POLAR MARINE SCIENCE GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR (MARCH 10-15, 2013 - FOUR POINTS SHERATON, VENTURA CA)

Energy Technology Data Exchange (ETDEWEB)

Bowman, Jeff S.

2012-12-15

As dynamic and thermodynamic processes associated with warming trends are impacting sea ice cover, oceanographic processes and atmosphere-ocean interactions across polar regions at unprecedented rate, observations and models show fundamentally different regional ecosystem responses. The non-linear and multi-directional biogeochemical responses of polar systems to atmospheric and oceanographic forcings emphasize the need to consider and reconcile observations and models at global and regional scales. The 9th GRC on Polar Marine Science will discuss recent developments and challenges emerging from contemporary and paleo-climate observations and models, encompassing regional and global scales. The GRC addresses the structure, functionalities and controls of polar marine systems through topics such as sea ice biogeochemistry, atmosphere-ocean forcings and interactions, food web trophodynamics, carbon and elemental cycling and fluxes, and a spectrum of ecological processes and interactions.

Spatial patterns in Central Asian climate and equilibrium line altitudes

International Nuclear Information System (INIS)

Rupper, Summer; Koppes, Michele

2010-01-01

A suite of general circulation model (GCM) simulations and a glacier equilibrium line altitude (ELA) model are compared to reconstructed glacier advances from geomorphic data and used to test the sensitivity of Central Asian glaciers to simulated climate changes at the Last Glacial Maximum (LGM). Results highlight temperature changes as being the most important influence on glacier ELA changes during the LGM. With the exception of the southern Himalaya, for much of Central Asia there is consistency between GCMs for simulated LGM temperature changes, with a mean cooling of 4 0 C. Further research will necessarily need to focus on detailed analysis of the inter-model differences in temperature in the southern Himalaya, and acquiring additional paleoclimate proxies in the region in order to further constrain the GCMs.

The Last Millennium Reanalysis: Improvements to proxies and proxy modeling

Science.gov (United States)

Tardif, R.; Hakim, G. J.; Emile-Geay, J.; Noone, D.; Anderson, D. M.

2017-12-01

The Last Millennium Reanalysis (LMR) employs a paleoclimate data assimilation (PDA) approach to produce climate field reconstructions (CFRs). Here, we focus on two key factors in PDA generated CFRs: the set of assimilated proxy records and forward models (FMs) used to estimate proxies from climate model output. In the initial configuration of the LMR [Hakim et al., 2016], the proxy dataset of [PAGES2k Consortium, 2013] was used, along with univariate linear FMs calibrated against annually-averaged 20th century temperature datasets. In an updated configuration, proxy records from the recent dataset [PAGES2k Consortium, 2017] are used, while a hierarchy of statistical FMs are tested: (1) univariate calibrated on annual temperature as in the initial configuration, (2) univariate against temperature as in (1) but calibration performed using expert-derived seasonality for individual proxy records, (3) as in (2) but expert proxy seasonality replaced by seasonal averaging determined objectively as part of the calibration process, (4) linear objective seasonal FMs as in (3) but objectively selecting relationships calibrated either on temperature or precipitation, and (5) bivariate linear models calibrated on temperature and precipitation with objectively-derived seasonality. (4) and (5) specifically aim at better representing the physical drivers of tree ring width proxies. Reconstructions generated using the CCSM4 Last Millennium simulation as an uninformed prior are evaluated against various 20th century data products. Results show the benefits of using the new proxy collection, particularly on the detrended global mean temperature and spatial patterns. The positive impact of using proper seasonality and temperature/moisture sensitivities for tree ring width records is also notable. This updated configuration will be used for the first generation of LMR-generated CFRs to be publicly released. These also provide a benchmark for future efforts aimed at evaluating the

Numerical Modeling of Rocky Mountain Paleoglaciers - Insights into the Climate of the Last Glacial Maximum and the Subsequent Deglaciation

Science.gov (United States)

Leonard, E. M.; Laabs, B. J. C.; Plummer, M. A.

2014-12-01

Numerical modeling of paleoglaciers can yield information on the climatic conditions necessary to sustain those glaciers. In this study we apply a coupled 2-d mass/energy balance and flow model (Plummer and Phillips, 2003) to reconstruct local last glacial maximum (LLGM) glaciers and paleoclimate in ten study areas along the crest of the U.S. Rocky Mountains between 33°N and 49°N. In some of the areas, where timing of post-LLGM ice recession is constrained by surface exposure ages on either polished bedrock upvalley from the LLGM moraines or post-LLGM recessional moraines, we use the model to assess magnitudes and rates of climate change during deglaciation. The modeling reveals a complex pattern of LLGM climate. The magnitude of LLGM-to-modern climate change (temperature and/or precipitation change) was greater in both the northern (Montana) Rocky Mountains and southern (New Mexico) Rocky Mountains than in the middle (Wyoming and Colorado) Rocky Mountains. We use temperature depression estimates from global and regional climate models to infer LLGM precipitation from our glacier model results. Our results suggest a reduction of precipitation coupled with strongly depressed temperatures in the north, contrasted with strongly enhanced precipitation and much more modest temperature depression in the south. The middle Rocky Mountains of Colorado and Wyoming appear to have experienced a reduction in precipitation at the LLGM without the strong temperature depression of the northern Rocky Mountains. Preliminary work on modeling of deglaciation in the Sangre de Cristo Range in southern Colorado suggests that approximately half of the LLGM-to-modern climate change took place during the initial ~2400 years of deglaciation. If increasing temperature and changing solar insolation were the sole drivers of this initial deglaciation, then temperature would need to have risen by slightly more than 1°C/ky through this interval to account for the observed rate of ice recession.

On the appropriate definition of soil profile configuration and initial conditions for land surface-hydrology models in cold regions

Science.gov (United States)

Sapriza-Azuri, Gonzalo; Gamazo, Pablo; Razavi, Saman; Wheater, Howard S.

2018-06-01

the temperature dynamics. We further show that our proposed initialization procedure is effective and robust to uncertainty in paleo-climate reconstructions and that more than 300 years of reconstructed climate time series are needed for proper model initialization.

Hemispherically Asymmetric Volcanic Forcing of Tropical Hydroclimate During the Last Millennium

Science.gov (United States)

Colose, Christopher M.; Legrande, Allegra N.; Vuille, Mathias

2016-01-01

Volcanic aerosols exert the most important natural radiative forcing of the last millennium. State-of-the-art paleoclimate simulations of this interval are typically forced with diverse spatial patterns of volcanic forcing, leading to different responses in tropical hydroclimate. Recently, theoretical considerations relating the intertropical convergence zone (ITCZ) position to the demands of global energy balance have emerged in the literature, allowing for a connection to be made between the paleoclimate simulations and recent developments in the understanding of ITCZ dynamics. These energetic considerations aid in explaining the well-known historical, paleoclimatic, and modeling evidence that the ITCZ migrates away from the hemisphere that is energetically deficient in response to asymmetric forcing. Here we use two separate general circulation model (GCM) suites of experiments for the last millennium to relate the ITCZ position to asymmetries in prescribed volcanic sulfate aerosols in the stratosphere and related asymmetric radiative forcing. We discuss the ITCZ shift in the context of atmospheric energetics and discuss the ramifications of transient ITCZ migrations for other sensitive indicators of changes in the tropical hydrologic cycle, including global streamflow. For the first time, we also offer insight into the large-scale fingerprint of water isotopologues in precipitation (delta sup 18 Op) in response to asymmetries in radiative forcing. The ITCZ shifts away from the hemisphere with greater volcanic forcing. Since the isotopic composition of precipitation in the ITCZ is relatively depleted compared to areas outside this zone, this meridional precipitation migration results in a large-scale enrichment (depletion) in the isotopic composition of tropical precipitation in regions the ITCZ moves away from (toward). Our results highlight the need for careful consideration of the spatial structure of volcanic forcing for interpreting volcanic signals in

Postglacial Records of Southern Hemisphere Climate and Oceanographic Change From the New Zealand Subantarctic Auckland Islands

Science.gov (United States)

Moy, C. M.; Gilmer, G.; Nichols, J. E.; Browne, I. M.; Curtin, L.; Vandergoes, M.; Aebig, C.; Wilson, G. S.

2017-12-01

The strength and latitudinal position of the Southern Hemisphere westerly winds (SHWW) play a fundamental role in influencing mid-latitude climate and CO2 exchange between the Southern Ocean and the atmosphere along seasonal to glaicial-interglacial timescales. Despite their importance, our understanding of past SHWW change is limited by the small number of paleoclimate records from the modern wind maximum, which are often not in agreement. The New Zealand subantarctic Auckland Islands are located within the core of the modern wind belt (50°S), a key latitude where ocean-atmospheric linkages between the Antarctic and mid-latitudes are strong. In contrast to other subantarctic islands on the Campbell Plateau, the Auckland Islands have multiple protected fjord sub-basins, deep lakes, and peatlands that are advantageous for the development of high-resolution paleoclimate records. We will present ongoing work towards the establishment of multi-proxy and multi-site reconstructions of past SHWW variability from the Auckland Islands. Modern process and paleoclimate studies suggest that in lacustrine and fjord settings, the degree of water column mixing, the stable isotopic composition of n-alkanes and benthic foraminifera, and the influx of terrestrial organic matter are good indicators of wind-induced mixing of the water column or precipitation-driven erosion within catchments. During the Late Glacial and early Holocene (15 to 9 ka), elevated long-chain n-alkane δD values from ombrotrophic peatlands and an increase in the concentration of redox-sensitive elements in fjord sediment cores, signal weakening of the SHWW that appears to be coincident with periods of rapid deglacial warming of West Antarctica. Since 5.5 ka, we interpret declining n-alkane δD values to indicate enhanced westerly flow. These interpretations are in broad agreement with terrestrial paleoclimate records developed from southern South America and argue for a symmetrical response of the SHWW during

LinkedEarth and 21st century paleoclimatology: reducing data friction through standard development

Science.gov (United States)

Khider, D.; Emile-Geay, J.; McKay, N.; Garijo, D.; Ratnakar, V.; Gil, Y.; Zhu, F.

2017-12-01

Paleoclimate observations are crucial to assessing current climate change in the context of past variations. However, these observations usually come in non-standard formats, forcing paleogeoscientists to spend a significant fraction of their time searching and accessing the data they need, in the form they need it. In the 21st century, we should do much better. The EarthCube-supported LinkedEarth project is manifesting a better future by creating an online platform that (1) enables the curation of a publicly-accessible database by paleoclimate experts themselves, and (2) fosters the development of community standards. In 2016, a workshop on paleoclimate data standards served as a focal point to initiate this process. Workshop participants identified the necessity to distinguish a set of essential, recommended, and desired properties for each dataset. A consensus emerged that these levels are archive-specific, as what is needed to intelligently re-use marine-annually resolved records could be quite different than what is needed to intelligently re-use an ice core records, for instance. It was therefore decided that archive-centric working groups (WGs) would be best positioned to elaborate and discuss the components of a data standard for their specific sub-field of paleoclimatology. It is also critical to ensure interoperability between standards to enable multi-proxy investigations; to that end, longitudinal WGs were created, and the LinkedEarth leadership regularly monitors WG activity to ensure cross-pollination and consistency. These WGs carried out their discussions on the LinkedEarth online platform, providing the foundation for a preliminary standard that could be voted on by the rest of the community. In this presentation, I will showcase this preliminary paleoclimate data standard and dwell on community engagement through the use of online polls on the LinkedEarth platform, Twitter, and email-distributed online surveys. Finally, I will demonstrate how

Derivation and validation of a multivariable model to predict when primary care physicians prescribe antidepressants for indications other than depression

Directory of Open Access Journals (Sweden)

Wong J

2018-04-01

Full Text Available Jenna Wong, Michal Abrahamowicz, David L Buckeridge, Robyn Tamblyn Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC, Canada Objective: Physicians commonly prescribe antidepressants for indications other than depression that are not evidence-based and need further evaluation. However, lack of routinely documented treatment indications for medications in administrative and medical databases creates a major barrier to evaluating antidepressant use for indications besides depression. Thus, the aim of this study was to derive a model to predict when primary care physicians prescribe antidepressants for indications other than depression and to identify important determinants of this prescribing practice. Methods: Prediction study using antidepressant prescriptions from January 2003–December 2012 in an indication-based electronic prescribing system in Quebec, Canada. Patients were linked to demographic files, medical billings data, and hospital discharge summary data to create over 370 candidate predictors. The final prediction model was derived on a random 75% sample of the data using 3-fold cross-validation integrated within a score-based forward stepwise selection procedure. The performance of the final model was assessed in the remaining 25% of the data. Results: Among 73,576 antidepressant prescriptions, 32,405 (44.0% were written for indications other than depression. Among 40 predictors in the final model, the most important covariates included the molecule name, the patient’s education level, the physician’s workload, the prescribed dose, and diagnostic codes for plausible indications recorded in the past year. The final model had good discrimination (concordance (c statistic 0.815; 95% CI, 0.787–0.847 and good calibration (ratio of observed to expected events 0.986; 95% CI, 0.842–1.136. Conclusion: In the absence of documented treatment indications, researchers may be able to use

Optimal estimation of atmospheric {sup 14}C production over the Holocene: paleoclimate implications

Energy Technology Data Exchange (ETDEWEB)

Marchal, Olivier [Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA (United States)

2005-01-01

A tree-ring {delta}{sup 14}C record and a simple box model of the global {sup 14}C cycle are combined using a method of optimal estimation theory (Rauch-Tung-Striebel smoother). The combination is used to infer information about the time evolution of {sup 14}C production in the atmosphere (P) for the period 9400 year BCto AD1900 year. Unlike previous attempts to infer P changes from the tree-ring record, the errors in both the {delta}{sup 14}C data and the model, which are assumed to be purely random (not systematic), are formally considered. The optimal time evolution of P is compared to independent evidence of changes in cosmogenic nuclide production over the Holocene from a variety of records on their original chronology, e.g., a record of the virtual axial dipole moment (VADM) based on a compilation of archeomagnetic data, the record of {sup 10}Be concentration from the GISP2 ice core (Central Greenland), and the record of {sup 10}Be concentration from the PS1 ice core (South Pole). The rank correlations between P - VADM,P - {sup 10}Be(GISP2), and P - {sup 10}Be(PS1) are highly significant (p< 0.01), indicating that geomagnetic field intensity and {sup 10}Be concentration in GISP2 and PS1 changed monotonically with {sup 14}C production. The linear correlation coefficients between P - VADM,P - {sup 10}Be(GISP2), and P - {sup 10}Be(PS1) are also highly significant (p<0.01) but relatively small (-0.76, 0.48, and 0.60, respectively). Thus, an important fraction (42-77%) of the variance in the geomagnetic and {sup 10}Be data is not accounted for by linear regression on the {sup 14}C productions implied by the tree-ring record. The P variance near the 1500 yr period, which previous authors interpreted as solar variability, represents a small fraction of the total variance in the P time series (<15% for the band 1200-1800 yr) and does not correspond to a spectral peak. Hence, the hypothesis of a direct solar forcing mechanism for the postulated millennial climate

What Can Earth Paleoclimates Reveal About the Resiliency of Habitable States? An Example from the Neoproterozoic Snowball Earth

Science.gov (United States)

Sohl, L.

2014-04-01

The Neoproterozoic "Snowball Earth" glaciations ( 750-635 Ma) have been a special focus for outer habitable zone investigations, owing in large part to a captivating and controversial hypothesis suggesting that Earth may have only narrowly escaped a runaway icehouse state on multiple occasions (a.k.a. "the hard snowball"; Hoffman and Schrag 2001). A review of climate simulations exploring snowball inception (Godderis et al. 2011) reveals that a broad range of models (EBMs, EMICs and AGCMs) tend to yield hard snowball solutions, whereas models with greater 3-D dynamic response capabilities (AOGCMs) typically do not, unless some of their climate feedback responses (e.g., wind-driven ocean circulation, cloud forcings) are disabled (Poulsen and Jacobs 2004). This finding raises the likelihood that models incorporating dynamic climate feedbacks are essential to understanding how much flexibility there may be in the definition of a planet's habitable zone boundaries for a given point in its history. In the first of a series of new Snowball Earth simulations, we use the NASA/GISS ModelE2 Global Climate Model - a 3-D coupled atmosphere/ocean model with dynamic sea ice response - to explore the impacts of wind-driven ocean circulation, clouds and deep ocean circulation on the sea ice front when solar luminosity and atmospheric carbon dioxide are reduced to Neoproterozoic levels (solar = 94%, CO2 = 40 ppmv). The simulation includes a realistic Neoproterozoic land mass distribution, which is concentrated at mid- to tropical latitudes. After 300 years, the sea ice front is established near 30 degrees latitude, and after 600 years it remains stable. As with earlier coupled model simulations we conclude that runaway glacial states would have been difficult to achieve during the Neoproterozoic, and would be more likely to have occurred during earlier times in Earth history when solar luminosity was less. Inclusion of dynamic climate feedback capabilities in habitable zone

Deep-Sea Corals: A New Oceanic Archive

National Research Council Canada - National Science Library

Adkins, Jess

1998-01-01

Deep-sea corals are an extraordinary new archive of deep ocean behavior. The species Desmophyllum cristagalli is a solitary coral composed of uranium rich, density banded aragonite that I have calibrated for several paleoclimate tracers...

The Role of the Tropics in Abrupt Climate Changes

Energy Technology Data Exchange (ETDEWEB)

Fedorov, Alexey [Yale University

2013-12-07

Topics addressed include: abrupt climate changes and ocean circulation in the tropics; what controls the ocean thermal structure in the tropics; a permanent El Niño in paleoclimates; the energetics of the tropical ocean.

Modeling the drift of massive icebergs to the subtropical North Atlantic

Science.gov (United States)

Condron, A.; Hill, J. C.

2013-12-01

New evidence from high-resolution seafloor bathymetry data indicates that massive (>300m thick) icebergs from the Laurentide Ice Sheet (LIS) drifted south to the tip of Florida during the last deglaciation. This finding is particularly exciting as it contradicts evidence from marine sediments that icebergs were mainly confined to the subpolar North Atlantic (50 - 70N) at this time. Indeed, the freshwater released from icebergs melting in the subpolar gyre is repeatedly cited as a main trigger for a slow-down of the Atlantic MOC in the past, and the possible cause of any climate cooling related to the melting of the Greenland Ice Sheet in the future. Using a sophisticated iceberg model (MITberg), coupled to a high (18-km; 1/6 deg.) resolution ocean model (MITgcm), we investigate the ocean circulation dynamics required to allow icebergs to drift to the southern tip of Florida. We find that icebergs only reach this location if they turn right at the Grand Banks of Newfoundland, and stay inshore of the Gulf Stream all the way to Florida. Modern-day circulation dynamics do not readily allow this to happen as cold, southward flowing, Labrador Current Water (important for iceberg survival) has little penetration south of Cape Hatteras. However, when a liquid meltwater flood is released from Hudson Bay at the same time, icebergs are rapidly transported (inshore of the Gulf Stream) in a narrow, buoyant, coastal current all the way to southern Florida. The meltwater and icebergs result in a significant freshening of the subtropical North Atlantic and weaken the strength of the Gulf Stream, suggesting such an event would have a large cooling effect on climate. We are only able to simulate the flow of meltwater and icebergs to the subtropics by modeling ocean circulation at a resolution that is 5 - 10 times higher than the majority of existing paleoclimate models; at lower resolutions the narrow, coastal boundary currents important for iceberg transport to the subtropics are

Modeling the stable water isotope expression of El Niño in the Pliocene: Implications for the interpretation of proxy data

Science.gov (United States)

Tindall, Julia C.; Haywood, Alan M.; Thirumalai, Kaustubh

2017-08-01

The El Niño-Southern Oscillation (ENSO) drives interannual climate variability; hence, its behavior over a range of climates needs to be understood. It is therefore important to verify that the paleoarchives, used for preinstrumental ENSO studies, can accurately record ENSO signals. Here we use the isotope enabled Hadley Centre General Circulation Model, HadCM3, to investigate ENSO signals in paleoarchives from a warm paleoclimate, the mid-Pliocene Warm Period (mPWP: 3.3-3.0 Ma). Continuous (e.g., coral) and discrete (e.g., foraminifera) proxy data are simulated throughout the tropical Pacific, and ENSO events suggested by the pseudoproxy data are assessed using modeled ENSO indices. HadCM3 suggests that the ability to reconstruct ENSO from coral data is predominantly dependent on location. However, since modeled ENSO is slightly stronger in the mPWP than the preindustrial, ENSO is slightly easier to detect in mPWP aged coral. HadCM3 also suggests that using statistics from a number of individual foraminifera (individual foraminifera analysis, IFA) generally provides more accurate ENSO information for the mPWP than for the preindustrial, particularly in the western and central Pacific. However, a test case from the eastern Pacific showed that for some locations, the IFA method can work well for the preindustrial but be unreliable for a different climate. The work highlights that sites used for paleo-ENSO analysis should be chosen with extreme care in order to avoid unreliable results. Although a site with good skill for preindustrial ENSO will usually have good skill for assessing mPWP ENSO, this is not always the case.

Impact of convective activity on precipitation δ18O in isotope-enabled models

Science.gov (United States)

Hu, J.; Emile-Geay, J.; Dee, S.

2017-12-01

The ^18O signal preserved in paleo-archives (e.g. speleothem, tree ring cellulose, ice cores) is widely used to reconstruct precipitation or temperature. In the tropics, the inverse relationship between precipitation ^18O and rainfall amount, namely "amount effect" [Dansgaard, Tellus, 1964], is often used to interpret precipitation ^18O. However, recent studies have shown that precipitation ^18O is also influenced by precipitation type [Kurita et al, JGR, 2009; Moerman et al, EPSL, 2013], and recent observations indicate that it is negatively correlated with the fraction of precipitation associated with stratiform clouds [Aggarwal et al, Nature Geosci, 2016]. It is thus important to determine to what extent isotope-enabled climate models can reproduce these relationships. Here we do so using output from LMDZ, CAM2, and isoGSM from the Stable Water Isotope Intercomparison Group, Phase 2 (SWING2) project and results of SPEEDY-IER [Dee et al, JGR, 2015] from an AMIP-style experiment. The results show that these models simulate the "amount effect" well in the tropics, and the relationship between precipitation ^18O and precipitation is reversed in many places in mid-latitudes, in accordance with observations [Bowen, JGR, 2008]. Also, these models can all reproduce the negative correlation between monthly precipitation ^18O and stratiform precipitation proportion in mid-latitude (30°N-50°N; 50°S-30°S), but in the tropics (30°S-30°N), models show a positive correlation instead. The reason for this bias will be investigated within idealized experiments with SPEEDY-IER. The correct simulations of the impact of convective activity on precipitation ^18O in isotope-enabled models will improve our interpretation of paleoclimate proxies with respect to hydroclimate variability. P. K. Aggarwal et al. (2016), Nature Geosci., 9, 624-629, doi:10.1038/ngeo2739. G. J. Bowen. (2008), J. Geophys. Res., 113, D05113, doi:10.1029/2007JD009295. W. Dansgaard (1964), Tellus, 16(4), 436

Droits en matière de sexualité et de reproduction, inégalités sociales ...

International Development Research Centre (IDRC) Digital Library (Canada)

Extrants. Évaluations. Derechos Sexuales y Reproductivos, Inequidad Social y Política en América : first evaluation report. Téléchargez le PDF. Contenus connexes. Le CRDI « analyse l'autonomisation des femmes » lors d'une conférence à l'Université McGill. Les conclusions d'un programme financé par le CRDI au ...

Évaluation organisationnelle | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

28 oct. 2011 ... Charles Lusthaus, Gary Anderson, Marie-Hélène Adrien et Elaine Murphy (CRDI 1995). Autres outils et ressources. Le site Web Reflect & Learn a vu le jour grâce à Universalia, au Center for Educational Leadership de l'Université McGill et au CRDI. Il a pour but d'améliorer l'évaluation organisationnelle ...

De la ferme à la fourchette : amélioration de la nutrition dans les ...

International Development Research Centre (IDRC) Digital Library (Canada)

Le taux d'obésité est à la hausse dans les Caraïbes, surtout en raison du peu ... suivi un cercle vicieux de piètre nutrition et d'obésité, qui met en danger la santé de la ... de l'Institut d'étude du développement international de l'Université McGill.

Optimized coral reconstructions of the Indian Ocean Dipole: An assessment of location and length considerations

Science.gov (United States)

Abram, Nerilie J.; Dixon, Bronwyn C.; Rosevear, Madelaine G.; Plunkett, Benjamin; Gagan, Michael K.; Hantoro, Wahyoe S.; Phipps, Steven J.

2015-10-01

The Indian Ocean Dipole (IOD; or Indian Ocean Zonal Mode) is a coupled ocean-atmosphere climate oscillation that has profound impacts on rainfall distribution across the Indian Ocean region. Instrumental records provide a reliable representation of IOD behavior since 1958, while coral reconstructions currently extend the IOD history back to 1846. Large fluctuations in the number and intensity of positive IOD events over time are evident in these records, but it is unclear to what extent this represents multidecadal modulation of the IOD or an anthropogenically forced change in IOD behavior. In this study we explore the suitability of coral records from single-site locations in the equatorial Indian Ocean for capturing information about the occurrence and magnitude of positive IOD (pIOD) events. We find that the optimum location for coral reconstructions of the IOD occurs in the southeastern equatorial Indian Ocean, along the coast of Java and Sumatra between ~3 and 7°S. Here the strong ocean cooling and atmospheric drying during pIOD events are unambiguously recorded in coral oxygen isotope records, which capture up to 50% of IOD variance. Unforced experiments with coupled climate models suggest that potential biases in coral estimates of pIOD frequency are skewed toward overestimating pIOD recurrence intervals and become larger with shorter reconstruction windows and longer pIOD recurrence times. Model output also supports the assumption of stationarity in sea surface temperature relationships in the optimum IOD location that is necessary for paleoclimate reconstructions. This study provides a targeted framework for the future generation of paleoclimate records, including optimized coral reconstructions of past IOD variability.

Difference in optimum temperature for growth and reproduction in benthic foraminifer Rosalina globularis: Implications for paleoclimatic studies

Digital Repository Service at National Institute of Oceanography (India)

Saraswat, R.; Nigam, R.; Pachkhande, S.

, P.A., Gabriel, J.J. 2010. Linkages between Holocene paleoclimate and paleohydrogeology preserved in a Yucatan underwater cave. Quat. Sci. Rev. 29, 2788-2798. 9 Leorri, E., Martin, R., McLaughlin, P. 2006. Holocene environmental and parasequence...

Navigating the clinical trial pathway: Conception, design, execution, and results dissemination.

Science.gov (United States)

Sampalis, John S; Watson, Joanne; Boukas, Stella; Boukas, Marianna; Harvey, Natalie; Machado, Sanjay; Bordeleau, Michel; Rampakakis, Emmanouil

2017-03-01

Dr Sampalis is founder, Chief Executive Officer, and Chief Scientific Officer of JSS Medical Research Inc, founded in 1997. He is a tenured professor of Surgery and Epidemiology & Biostatistics of McGill University, the University of Montreal and University of Laval. Recognized as a leading clinical epidemiologist and one of the top trauma researchers in Canada, he possesses extensive expertise in health services research, clinical trials, and offers services as a Research and Epidemiological Consultant for numerous pharmaceutical companies, hospitals and government organizations and agencies. Mrs. Watson holds a M.Sc. in Pharmacology from Dalhousie University, and a B.Sc. from the University of Western Ontario. Her experience extends to all facets of the CRO business, and multiple therapeutic areas. She co-founded, in 1992, Integrated Research Inc, a full-service contract research organization, and served as its President and Chief Executive Officer, until merging with JSS Medical Research Inc in 2014. Mrs. Watson currently holds the position of Chief Business Officer, and is head of the business development team. Mrs. Boukas has been working with the JSS Medical Research team since its inception in the 1990s. She holds a B.A. in Psychology from McGill University with training in Epidemiology and Biostatistics, and is certified by the Society of Clinical Research Associates (SOCRA) as a Certified Clinical Research Professional (CCRP). She has over 25 years' of experience in medical research management. Currently Chief Operations Officer, Mrs. Boukas has been essential in structuring and implementing programs at JSS Medical Research Inc to facilitate project management, site recruitment, data capture and study tracking. Mrs. Boukas holds a B.A. from McGill University, a Certificate in Technical Communications from Concordia University and has received compliance training from SNC Lavalin Pharma (SLP) and SOCRA. She has over twenty-five years' experience in

Directions in parallel processor architecture, and GPUs too

CERN Multimedia

CERN. Geneva

2014-01-01

Modern computing is power-limited in every domain of computing. Performance increments extracted from instruction-level parallelism (ILP) are no longer power-efficient; they haven't been for some time. Thread-level parallelism (TLP) is a more easily exploited form of parallelism, at the expense of programmer effort to expose it in the program. In this talk, I will introduce you to disparate topics in parallel processor architecture that will impact programming models (and you) in both the near and far future. About the speaker Olivier is a senior GPU (SM) architect at NVIDIA and an active participant in the concurrency working group of the ISO C++ committee. He has also worked on very large diesel engines as a mechanical engineer, and taught at McGill University (Canada) as a faculty instructor.

Hydrodynamic-driven stability analysis of morphological patterns on stalactites and implications for cave paleoflow reconstructions.

Science.gov (United States)

Camporeale, Carlo; Ridolfi, Luca

2012-06-08

A novel hydrodynamic-driven stability analysis is presented for surface patterns on speleothems, i.e., secondary sedimentary cave deposits, by coupling fluid dynamics to the geochemistry of calcite precipitation or dissolution. Falling film theory provides the solution for the flow-field and depth perturbations, the latter being crucial to triggering patterns known as crenulations. In a wide range of Reynolds numbers, the model provides the dominant wavelengths and pattern celerities, in fair agreement with field data. The analysis of the phase velocity of ridges on speleothems has a potential as a proxy of past film flow rates, thus suggesting a new support for paleoclimate analyses.

Using paleoclimate proxy-data to select an optimal realisation in an ensemble of simulations of the past millennium.

NARCIS (Netherlands)

Goosse, H.; Renssen, H.; Timmermann, A.; Bradley, R.S.; Mann, M.E.

2006-01-01

We present and describe in detail the advantages and limitations of a technique that combines in an optimal way model results and proxy-data time series in order to obtain states of the climate system consistent with model physics, reconstruction of past radiative forcing and proxy records. To

Focal Muscle Vibration and Physical Exercise in Postmastectomy Recovery: An Explorative Study

Directory of Open Access Journals (Sweden)

Claudia Celletti

2017-01-01

Full Text Available Background. Physical activity initiation and maintenance are particular challenges in the postmastectomy recovery and in particular Dragon Boat racing seems to be a useful sport activity. The aim of this study was to evaluate the role of focal muscle vibration as a proprioceptive input to improve upper limb functioning in a group of “paddlers” patients. Methods. A group of paddlers has been evaluated before vibratory treatment (T0, immediately after therapy (T1, after one week (T2, and after one month (T3 with DASH questionnaire, Body Image Scale, McGill pain questionnaire, Constant Scale, and Short Form 36 questionnaire. Results. Fourteen patients showed a significant reduction in disability score (p=0,001 using DASH scale, an improvement of upper limb function (p=0,001 using the Constant scale, and a reduction of pain (p=0,007 at the McGill pain questionnaire. The Mental Composite Score of the Short Form 36 questionnaire showed significant results (p=0,04 while no significant results had been found regarding the physical mental score (p=0,08. Conclusion. Focal muscle vibration may be a useful treatment in a postmastectomy recovery of upper limb functionality.

Synchronizing early Eocene deep-sea and continental records - cyclostratigraphic age models for the Bighorn Basin Coring Project drill cores

Science.gov (United States)

Westerhold, Thomas; Röhl, Ursula; Wilkens, Roy H.; Gingerich, Philip D.; Clyde, William C.; Wing, Scott L.; Bowen, Gabriel J.; Kraus, Mary J.

2018-03-01

A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, at 56-54 Ma, show the impact of large-scale carbon input into the ocean-atmosphere system. Here we provide the first timescale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity-modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ˜ 200 kyr for the carbon isotope excursion and ˜ 120 kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biota ˜ 200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a second generation of apical spine-bearing sphenolith species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.

Redox stratification of an ancient lake in Gale crater, Mars.

Science.gov (United States)

Hurowitz, J A; Grotzinger, J P; Fischer, W W; McLennan, S M; Milliken, R E; Stein, N; Vasavada, A R; Blake, D F; Dehouck, E; Eigenbrode, J L; Fairén, A G; Frydenvang, J; Gellert, R; Grant, J A; Gupta, S; Herkenhoff, K E; Ming, D W; Rampe, E B; Schmidt, M E; Siebach, K L; Stack-Morgan, K; Sumner, D Y; Wiens, R C

2017-06-02

In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized. Copyright © 2017, American Association for the Advancement of Science.

Devon island ice cap: core stratigraphy and paleoclimate.

Science.gov (United States)

Koerner, R M

1977-04-01

Valuable paleoclimatic information can be gained by studying the distribution of melt layers in deep ice cores. A profile representing the percentage of ice in melt layers in a core drilled from the Devon Island ice cap plotted against both time and depth shows that the ice cap has experienced a period of very warm summers since 1925, following a period of colder summers between about 1600 and 1925. The earlier period was coldest between 1680 and 1730. There is a high correlation between the melt-layer ice percentage and the mass balance of the ice cap. The relation between them suggests that the ice cap mass balance was zero (accumulation equaled ablation) during the colder period but is negative in the present warmer one. There is no firm evidence of a present cooling trend in the summer conditions on the ice cap. A comparison with the melt-layer ice percentage in cores from the other major Canadian Arctic ice caps shows that the variation of summer conditions found for the Devon Island ice cap is representative for all the large ice caps for about 90 percent of the time. There is also a good correlation between melt-layer percentage and summer sea-ice conditions in the archipelago. This suggests that the search for the northwest passage was influenced by changing climate, with the 19th-century peak of the often tragic exploration coinciding with a period of very cold summers.

Nature et acteurs de la violence urbaine en République ...

International Development Research Centre (IDRC) Digital Library (Canada)

... de la violence, les formes et modes d'action par lesquels les villes congolaises, ... de l'Institut d'étude du développement international de l'Université McGill ... des données probantes sur l'autonomisation des femmes sur le marché du travail. ... Droits d'auteur · Éthique de la recherche · Politique de libre accès · Politique ...

Vaincre le vampire violet | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

26 janv. 2011 ... ... de s'assurer que l'arme fongique découverte par Alan Watson ne se transforme en mercenaire et cause la destruction d'autres espèces végétales, Fusarium oxysporum a été soumis pendant deux ans à une batterie de tests dans les laboratoires hautement sécurisés de McGill, sur le campus Macdonald.

Pathophysiology of Post Amputation Pain

Science.gov (United States)

2014-12-01

Short Form (MPQ), Center for Epidemiological Studies Depression Scale (CES-D 10), Pain and Anxiety Symptoms Scale, short version (PASS-20), and the...analyzed by independent samples t-test comparing McGill Pain Questionnaire – Short Form (MPQ), VAS, Pain Anxiety Symptoms Scale (PASS), Center for...Systemic alpha- adrenergic blockade with phentolamine: a diagnostic test for sympathetically maintained pain. Anesthesiology 1991;74:691-8. 71

Curvatures Estimation in Orientation Selection

Science.gov (United States)

1991-01-31

t Dept. of Opthalmology University of British Columbia Vancouver, B. C. Postal Address: 3480 University Street, Montrial, Quibec. Canada H-3A 2A7...Advanced Research t Dept. of Opthalmology . University of British Columbia. Vancouver. B C Canada Running Title: Analysis of a Quasi-Linear Endstopped...Intelligent Machines McGill University Montreal, Quebec, Canada * Fellow, Canadian Institute for Advanced Research t Dept. of Opthalmology , University of

The last glacial cycle documented on the Lower Bengal Fan - chronological and paleoclimate implications

Science.gov (United States)

Weber, M. E.; Dekens, P.; Reilly, B.; Lantzsch, H.; Selkin, P. A.; Das, S. K.; Williams, T.; Martos, Y. M.; Adhikari, R. R.; Gyawali, B. R.; Jia, G.; Fox, L. R.; Ge, J.; Manoj, M. C.; Savian, J. F.; Meynadier, L.; Spiess, V.; France-Lanord, C.; Klaus, A.

2016-12-01

IODP Expedition 354 set out in February to March 2015 to drill seven sites along an east west oriented core transect of 320 km length at 8°N in the Bengal Fan (France-Lanord et al., 2015). Sediments show complex intercalation of turbiditic and hemipelagic deposits, documenting the interaction of fan evolution and paleoceanographic history. Hemipelagic sequences represent a several meter thick top layer of Late Quaternary sediment. Deposits are either rich in biogenic opal/clay or in carbonate. We studied physical, optical, geochemical, grain-size, and stable isotopic properties of this top layer to establish a time frame, estimate sedimentary properties, and assess the development of the region during the last glacial cycle. For this purpose, we sampled Site U1452C-1H continuously for the uppermost 480 cm in 2-cm increments. Preliminary results indicate the Toba Ash 1 (74 ka) is a distinct time marker in most physical property data sets. Records of wet-bulk density as well as color reflectance b* (the red-green component) and L* (the lightness) show a dominant precession cyclicity. Hence, we are able to provide an insolation-tuned chronology for the last 200 ka (MIS1 - 7). These records agree well with d18O records retrieved from Chinese caves. An independent age model is derived from records of relative paleointensity (RPI), including the assessment of the Laschamp Event ( 40 ka), and on RPI tuning to global templates. We will compare both chronologies and evaluate their chronological and paleoclimatic implications. We will also present preliminary grain-size and paleoceanographic proxy data (sea-surface temperature, sea-surface salinity, and Mg/Ca) as well as color endmember modeling to reconstruct ice volume, marine biological productivity, nutrient supply, and deep-water circulation. The sedimentologic, oceanographic and climatic conditions are linked to changes in monsoonal strength and terrestrial input, which will also be studied using sedimentary proxies

High-Resolution Modeling of ENSO-Induced Precipitation in the Tropical Andes: Implications for Proxy Interpretation.

Science.gov (United States)

Kiefer, J.; Karamperidou, C.

2017-12-01

Clastic sediment flux into high-elevation Andean lakes is controlled by glacial processes and soil erosion caused by high precipitation events, making these lakes suitable archives of past climate. To wit, sediment records from Laguna Pallcacocha in Ecuador have been interpreted as proxies of ENSO variability, owing to increased precipitation in the greater region during El Niño events. However, the location of the lake's watershed, the presence of glaciers, and the different impacts of ENSO on precipitation in the eastern vs western Andes have challenged the suitability of the Pallcacocha record as an ENSO proxy. Here, we employ WRF, a high-resolution regional mesoscale weather prediction model, to investigate the circulation dynamics, sources of moisture, and resulting precipitation response in the L. Pallcacocha region during different flavors of El Niño and La Niña events, and in the presence or absence of ice caps. In patricular, we investigate Eastern Pacific (EP), Central Pacific (CP), coastal El Niño, and La Niña events. We validate the model simulations against spatially interpolated station measurements and reanalysis data. We find that during EP events, moisture is primarily advected from the Pacific, whereas during CP events, moisture primarily originates from the Atlantic. More moisture is available during EP events, which implies higher precipitation rates. Furthermore, we find that precipitation during EP events is mostly non-convective in contrast to primarily convective precipitation during CP events. Finally, a synthesis of the sedimentary record and the EP:CP ratio of accumulated precipitation and specific humidity in the L. Pallcacocha region allows us to assess whether past changes in the relative frequency of the two ENSO flavors may have been recorded in paleoclimate archives in this region.

Inferring climate variability from skewed proxy records

Science.gov (United States)

Emile-Geay, J.; Tingley, M.

2013-12-01

Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and

Towards a climate event stratigraphy for New Zealand over the past 30,000 years

International Nuclear Information System (INIS)

Barrell, D.J.A.; Alloway, B.V.; Shulmeister, J.; Newnham, R.M.

2005-01-01

A poster summarizing a representative selection of evidence for environmental conditions and climate change in New Zealand during the last 30,000 years has been prepared as a 'first-step' contribution to the INTIMATE (INTegration of Ice-core, Marine and TerrEstrial records) initiative of the INQUA Paleoclimate Commission. This international initiative aims to establish a more detailed knowledge of the nature, timing and regional to global extent of climatic and environmental changes associated with the Last Termination. The poster depicts key New Zealand onshore and offshore records for the Last Glacial Maximum and the Last Glacial-Interglacial Transition, from a variety of latitudes and elevations. Inset maps show New Zealand's oceanographic setting, principal currents and water masses, extent of glaciers, and distribution of vegetation zones at approximately 22,000 calendar years ago and at modern times (incorporating the inferred vegetation distribution at c. 1250 AD, before deforestation associated with human settlement). A calendar-age timescale is based on a combination of volcanic ash (tephra) and radiometric dates. Paleoclimate records from ice cores from Antarctica and Greenland are presented for comparison with New Zealand records. High-resolution records are presented for sediment-filled volcanic craters in Auckland (total carbon, carbon isotopes and pollen), wetlands in northeast North Island, central North Island and western South Island (pollen), marine sediments off eastern North Island (oxygen isotopes), and stalagmites in caves in northwest South Island (carbon and oxygen isotopes). In addition, the poster includes a range of lower resolution or fragmentary records of climate events, based on glacial landforms and deposits (central Southern Alps, South Island), river terraces and deposits, loess deposits (eastern North and South Islands), and Aeolian quartz silt in non-quartzose, loess-like, andesitic tephric deposits of western North Island. The

Paleoenvironmental inference models from sediment diatom assemblages in Baffin Island lakes (Nunavut, Canada) and reconstruction of summer water temperature

Energy Technology Data Exchange (ETDEWEB)

Joynt, E. H. III; Wolfe, A. P. [Colorado Univ., Inst. of Arctic and Alpine Research, Boulder, CO (United States)

2001-06-01

Lake sediments are attractive repositories for paleoclimate proxy data because they are temporally continuous, undisturbed and datable. It is particularly true of lakes which are ubiquitous throughout the Arctic regions, enabling dense spatial coverage of sampling sites. In more recent times diatoms have been applied to a a variety of paleoenvironmental questions. However, these studies have been of limited usefulness because they lack a regional training set that would facilitate making quantitative paleoenvironmental inferences. This article provides this inferential tool, together with an example of its application. Conductivity, pH, summer lake water temperature, and mean annual air temperature have been identified as the significant controls over diatom assemblages from the surface sediments of 61 lakes on Baffin Island. Using weighted-averaging regression and calibration, predictive models for these parameters have been developed. Results show that the summer lake water temperature model provides realistic reconstructions when compared with other paleoenvironmental records. Over the past 5000 years the amplitude of reconstructed summer lake water temperature was found to be on the order of 4 degrees C, expressed primarily as progressive neoglacial cooling culminating in the Little Ice Age. Diatom-inferred summer water temperatures have increased by about 2 degrees C in the past 150 years, which is also in agreement with independent paleoclimatic reconstructions. The data obtained in this study complements similar efforts from the western Canadian Arctic and the northern reaches of Scandinavia, however, this is the first training set developed for lakes situated entirely north of the tree line. As such, it extends the applicability of diatoms for paleotemperature reconstructions well into the Arctic tundra biome. 45 refs., 1 tab., 10 figs., 1 appendix.

On the appropriate definition of soil profile configuration and initial conditions for land surface–hydrology models in cold regions

Directory of Open Access Journals (Sweden)

G. Sapriza-Azuri

2018-06-01

adequately represent the temperature dynamics. We further show that our proposed initialization procedure is effective and robust to uncertainty in paleo-climate reconstructions and that more than 300 years of reconstructed climate time series are needed for proper model initialization.

Temperature and heat flux changes at the base of Laurentide ice sheet inferred from geothermal data (evidence from province of Alberta, Canada)

Czech Academy of Sciences Publication Activity Database

Demezhko, D.; Gornostaeva, A.; Majorowicz, J.; Šafanda, Jan

2018-01-01

Roč. 107, č. 1 (2018), s. 113-121 ISSN 1437-3254 Institutional support: RVO:67985530 Keywords : borehole temperature * paleoclimate reconstruction * surface heat flux * ground surface temperature * Laurentide ice sheet Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.283, year: 2016

Middle Moscovian climate of eastern equatorial Pangea recorded in paleosols and fluvial architecture

Czech Academy of Sciences Publication Activity Database

Opluštil, S.; Lojka, R.; Rosenau, N.A.; Strnad, L.; Sýkorová, Ivana

2015-01-01

Roč. 440, DEC (2015), s. 328-352 ISSN 0031-0182 Institutional support: RVO:67985891 Keywords : Carboniferous paleoclimate * fluvial architectures * paleosols * geochemistry Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.525, year: 2015 http://www.sciencedirect.com/science/article/pii/S0031018215004939

Transient coupling relationships of the Holocene Australian monsoon

Science.gov (United States)

McRobie, F. H.; Stemler, T.; Wyrwoll, K.-H.

2015-08-01

The northwest Australian summer monsoon owes a notable degree of its interannual variability to interactions with other regional monsoon systems. Therefore, changes in the nature of these relationships may contribute to variability in monsoon strength over longer time scales. Previous attempts to evaluate how proxy records from the Indonesian-Australian monsoon region correspond to other records from the Indian and East Asian monsoon regions, as well as to El Niño-related proxy records, have been qualitative, relying on 'curve-fitting' methods. Here, we seek a quantitative approach for identifying coupling relationships between paleoclimate proxy records, employing statistical techniques to compute the interdependence of two paleoclimate time series. We verify the use of complex networks to identify coupling relationships between modern climate indices. This method is then extended to a set of paleoclimate proxy records from the Asian, Australasian and South American regions spanning the past 9000 years. The resulting networks demonstrate the existence of coupling relationships between regional monsoon systems on millennial time scales, but also highlight the transient nature of teleconnections during this period. In the context of the northwest Australian summer monsoon, we recognise a shift in coupling relationships from strong interhemispheric links with East Asian and ITCZ-related proxy records in the mid-Holocene to significantly weaker coupling in the later Holocene. Although the identified links cannot explain the underlying physical processes leading to coupling between regional monsoon systems, this method provides a step towards understanding the role that changes in teleconnections play in millennial-to orbital-scale climate variability.

Competitive platinum-group-metal (PGM) supply from the Eastern Limb, Bushveld Complex: Geological, mining and mineral economic aspects

CSIR Research Space (South Africa)

McGill, JE

2011-08-01

Full Text Available -GROUP-METAL (PGM) SUPPLY FROM THE EASTERN LIMB, BUSHVELD COMPLEX: GEOLOGICAL, MINING, AND MINERAL ECONOMIC ASPECTS Dr. Jeannette E. McGill & Prof. Murray W. Hitzman ACKNOWLEDGEMENTS ? COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH (CSIR) ? Centre for Mining... Innovation ? Office of Graduate Studies, Fogarty Endowment ? Mr. VISHNU PILLAY (EXECUTIVE HEAD: JV?S ? Anglo Platinum) ? ACADEMIC ADVISORS Prof. Murray Hitzman (Economic Geology); Dr. Hugh Miller (Mining Engineering); Prof. Rodderick Eggert (Mineral...

Star laws: legal controls on armed conflict in outer space

International Nuclear Information System (INIS)

Stephens, Dale

2016-01-01

An undeclared military space race is unfolding yet there is no clear understanding of how international las operates in the field of armed conflict in outer space. In conjunction with McGill University Law School, Montreal, Canada, a 'Manual on international law applicable to military uses of outer space' has been drafted. This article looks at types of space weapons, previous space treaties and discusses humanitarian law.

Predicting early epidurals: association of maternal, labor, and neonatal characteristics with epidural analgesia initiation at a cervical dilation of 3 cm or less

OpenAIRE

Moore, Albert; Li Pi Shan,William; Hatzakorzian,Roupen

2013-01-01

Albert R Moore, William Li Pi Shan, Roupen Hatzakorzian Department of Anaesthesia, McGill University Health Centre, Royal Victoria Hospital, Montreal, Quebec, Canada Background: Retrospective studies have associated early epidural analgesia with cesarean delivery, but prospective studies do not demonstrate a causal relationship. This suggests that there are other variables associated with early epidural analgesia that increase the risk of cesarean delivery. This study was undertaken to deter...

Cultural consultation as a model for training multidisciplinary mental healthcare professionals in cultural competence skills: preliminary results.

Science.gov (United States)

Owiti, J A; Ajaz, A; Ascoli, M; de Jongh, B; Palinski, A; Bhui, K S

2014-01-01

Lack of cultural competence in care contributes to poor experiences and outcomes from care for migrants and racial and ethnic minorities. As a result, health and social care organizations currently promote cultural competence of their workforce as a means of addressing persistent poor experiences and outcomes. At present, there are unsystematic and diverse ways of promoting cultural competence, and their impact on clinician skills and patient outcomes is unknown. We developed and implemented an innovative model, cultural consultation service (CCS), to promote cultural competence of clinicians and directly improve on patient experiences and outcomes from care. CCS model is an adaptation of the McGill model, which uses ethnographic methodology and medical anthropological knowledge. The method and approach not only contributes both to a broader conceptual and dynamic understanding of culture, but also to learning of cultural competence skills by healthcare professionals. The CCS model demonstrates that multidisciplinary workforce can acquire cultural competence skills better through the clinical encounter, as this promotes integration of learning into day-to-day practice. Results indicate that clinicians developed a broader and patient-centred understanding of culture, and gained skills in narrative-based assessment method, management of complexity of care, competing assumptions and expectations, and clinical cultural formulation. Cultural competence is defined as a set of skills, attitudes and practices that enable the healthcare professionals to deliver high-quality interventions to patients from diverse cultural backgrounds. Improving on the cultural competence skills of the workforce has been promoted as a way of reducing ethnic and racial inequalities in service outcomes. Currently, diverse models for training in cultural competence exist, mostly with no evidence of effect. We established an innovative narrative-based cultural consultation service in an inner

The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)

NARCIS (Netherlands)

Sier, Mark J.; Langereis, Cor G.; Dupont-Nivet, Guillaume; Feibel, Craig S.; Joordens, Josephine C.A.; van der Lubbe, Jeroen H.J.L.; Beck, Catherine C.; Olago, Daniel; Cohen, Andrew

2017-01-01

One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from

The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)

NARCIS (Netherlands)

Sier, Mark J.; Langereis, Cor G.; Dupont-Nivet, Guillaume; Feibel, Craig S.; Joordens, Josephine C.A.; van der Lubbe, H.J.L.; Beck, Catherine; Olago, Daniel; Cohen, Andrew

2017-01-01

Abstract One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

NARCIS (Netherlands)

Tsyganov, A.N.; Aerts, R.; Nijs, I.; Cornelissen, J.H.C.; Beyens, L.

2012-01-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming,

Pedo-chemical climate proxies in Late Pleistocene Serbian-Ukranian loess sequences

NARCIS (Netherlands)

Bokhorst, M.P.; Beets, C.J.; Markovic, S.B.; Gerasimenko, N.P.; Matviishina, Z.N.; Frechen, M.

2009-01-01

The last glacial-interglacial loess-paleosol sequences of Serbia and Ukraine provide a good climate reconstruction potential for this part of Europe. Four loess sections distributed over an area with present-day moist to semi-arid climates were studied. In addition to traditional paleoclimate

Integrating components of the earth system to model global climate changes: implications for the simulation of the climate of the next million years

International Nuclear Information System (INIS)

Duplessy, J.C.

2009-01-01

The climate system is complex because it is made up of several components (atmosphere, ocean, sea ice, continental surface, ice sheets), each of which has its own response time. The paleo-climate record provides ample evidence that these components interact nonlinearly with each other and also with global biogeochemical cycles, which drive greenhouse gas concentration in the atmosphere. Forecasting the evolution of future climate is therefore an extremely complex problem. In addition, since the nineteenth century, human activities are releasing great quantities of greenhouse gases (CO 2 , CH 4 , CFC, etc.) into the atmosphere. As a consequence, the atmospheric content of these gases has tremendously increased. As they have a strong greenhouse effect, their concentration is now large enough to perturb the natural evolution of the earth's climate. In this paper, we shall review the strategy which has been used to develop and validate tools that would allow to simulate the future long-term behaviour of the Earth's climate. This strategy rests on two complementary approaches: developing numerical models of the climate system and validating them by comparing their output with present-day meteorological data and paleo-climatic reconstructions. We shall then evaluate the methods available to simulate climate at the regional scale and the major uncertainties that must be solved to reasonable estimate the long-term evolution of a region, which would receive a geological repository for nuclear wastes. (author)

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2001-09-14

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 1 of the project has been reservoir description and characterization. This effort has included four tasks: (1) geoscientific reservoir characterization, (2) the study of rock-fluid interactions, (3) petrophysical and engineering characterization and (4) data integration. This work was scheduled for completion in Year 1. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been initiated. Observations regarding the diagenetic processes influencing pore system development and heterogeneity in these reef and shoal reservoirs have been

Carbon isotope exchange between gaseous CO2 and thin solution films: Artificial cave experiments and a complete diffusion-reaction model

Science.gov (United States)

Hansen, Maximilian; Scholz, Denis; Froeschmann, Marie-Louise; Schöne, Bernd R.; Spötl, Christoph

2017-08-01

Speleothem stable carbon isotope (δ13C) records provide important paleoclimate and paleo-environmental information. However, the interpretation of these records in terms of past climate or environmental change remains challenging because of various processes affecting the δ13C signals. A process that has only been sparsely discussed so far is carbon isotope exchange between the gaseous CO2 of the cave atmosphere and the dissolved inorganic carbon (DIC) contained in the thin solution film on the speleothem, which may be particularly important for strongly ventilated caves. Here we present a novel, complete reaction diffusion model describing carbon isotope exchange between gaseous CO2 and the DIC in thin solution films. The model considers all parameters affecting carbon isotope exchange, such as diffusion into, out of and within the film, the chemical reactions occurring within the film as well as the dependence of diffusion and the reaction rates on isotopic mass and temperature. To verify the model, we conducted laboratory experiments under completely controlled, cave-analogue conditions at three different temperatures (10, 20, 30 °C). We exposed thin (≈0.1 mm) films of a NaHCO3 solution with four different concentrations (1, 2, 5 and 10 mmol/l, respectively) to a nitrogen atmosphere containing a specific amount of CO2 (1000 and 3000 ppmV). The experimentally observed temporal evolution of the pH and δ13C values of the DIC is in good agreement with the model predictions. The carbon isotope exchange times in our experiments range from ca. 200 to ca. 16,000 s and strongly depend on temperature, film thickness, atmospheric pCO2 and the concentration of DIC. For low pCO2 (between 500 and 1000 ppmV, as for strongly ventilated caves), our time constants are substantially lower than those derived in a previous study, suggesting a potentially stronger influence of carbon isotope exchange on speleothem δ13C values. However, this process should only have an

Transforming the diagnosis of tuberculosis: an editorial board member's opinion at the 15th year of Expert Review of Molecular Diagnostics.

Science.gov (United States)

Pai, Madhukar; Raison, Claire

2015-03-01

Interview with Professor Madhukar Pai, MD, PhD by Claire Raison (Commissioning Editor). Professor Madhukar Pai did his medical training and community medicine residency in Vellore, India. He completed his PhD in epidemiology at the University of California, Berkeley (CA, USA) and a postdoctoral fellowship at the University of California, San Francisco (CA, USA). He is currently an associate professor of epidemiology at McGill University in Montreal (Canada). He serves as the Director of Global Health Programs, and as an Associate Director of the McGill International Tuberculosis Centre. In addition, he serves as a Consultant for the Bill & Melinda Gates Foundation. He also serves on the Scientific Advisory Committee of the Foundation for Innovative New Diagnostics, Geneva, Switzerland. His research is focused on improving the diagnosis and treatment of tuberculosis, especially in high-burden countries such as India and South Africa. His research is supported by grant funding from the Gates Foundation, Grand Challenges Canada and Canadian Institutes of Health Research. He has more than 200 peer-reviewed publications. He is recipient of the Union Scientific Prize, Chanchlani Global Health Research Award and Stars in Global Health award from Grand Challenges Canada, and is a member of the Royal Society of Canada.

(Semi)volatile organic compounds and microbiological entities in snow during OASIS Barrow 2009

Science.gov (United States)

Ariya, P.; Kos, G.

2009-12-01

Gregor Kos (1), Nafissa Adechina (2), Dwayne Lutchmann (2) , Roya Mortazavi, and Parisa Ariya* (1), (2) (1) McGill University, Department of Atmospheric and Oceanic Sciences, 805 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada (2) McGill University, Department of Chemistry, 801 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada an active medium for the deposition of (semi-)volatile (bio)organic compounds. We collected surface snow samples during the OASIS Barrow campaign in March 2009 for analysis of semi-volatile organic compounds using solid phase microextraction and gas chromatography with mass spectrometric detection (SPME-GC/MS). Additioal gab samples were taken for analysis of non-methane hydrocarbons in air. More over, we analyzed for microbial species in air and snow. Identifed organic compounds covered a wide range of functionalities andmolecular weigts, including oxygenated reactive speces such as aldehydes (e.g., hexanal to decanal), alcohols (e.g., hexanol, octanol) and aromatic species (e.g., methyl- and ethylbenzenes). Quantification data for selected aromatic species are presented with concentrations in the upper ng/L range. We will present our preliminary data on microbiological species, and will discuss the potential mplications of the results for organic snow chemistry.

Paleoclimatology: a survey on ancient climates. Volume 1 - To find, date and interpret indices; Volume 2 - To fit the puzzle pieces one to the other: to understand and model a complex system

International Nuclear Information System (INIS)

Duplessy, J.C.; Ramstein, G.; Berger, A.; Joussaume, S.; Guillou, H.; Paterne, M.; Michel, E.; Hatte, C.; Dutay, J.C.; Nomade, S.; Scaillet, S.; Frank, N.; Salle, E.; Laj, C.; Channell, J.E.T.; Kissel, C.; Guibal, F.; Guiot, J.; Parrenin, F.; Masson-Delmotte, V.; Jouzel, J.; Rousseau, D.D.; Genty, D.; Von Grafenstein, U.; Belmecheri, S.; Daux, V.; Williamson, D.; Gasse, F.; Vimeux, F.; Cortijo, E.; Labeyrie, L.; Bopp, L.; Friedlingstein, P.; Chappellaz, J.; Legrand, M.; Delmas, R.; Ritz, C.; Peyaud, V.; Waelbroeck, C.; Colleoni, F.; Fluteau, F.; Kageyama, M.; Paillard, D.; Godderis, Y.; Le Hir, G.; Donnadieu, Y.; Roche, D.M.; Combourieu Nebout, N.; Braconnot, P.; Yiou, P.; Charbit, S.; Dufresne, J.L.; Cattiaux, J.

2013-11-01

The first volume of this collective publication gathers contributions on techniques used to reconstruct past climates. The chapters address the climate system operation and history (evolution, mechanisms, the atmosphere, oceans, ground and marine biosphere, cryo-sphere, lithosphere), propose an introduction to geochronology, present and discuss various dating methods (carbon 14, K-Ar and Ar-Ar methods, dating of corals and other geological samples based the disequilibrium between uranium and thorium isotopes, use of magnetic stratigraphy, dendro-chronology, dating of ice archives), discuss how to reconstruct atmosphere physics and circulation, address the use and properties of different interfaces (air-ice with polar ices, air-plants with pollen, air-soil with loessic sequences as markers of atmospheric circulation or reconstruction of paleo-climates with speleothems, air-lake, plant-atmosphere, air-plant, air-water, air-ice in tropical glaciers), and discuss the use of paleo-oceanography data. The second volume gathers contributions in which the authors present the most recent approaches used to reconstruct the operation of the climate system in the past by using present observations and models. The chapters address the biochemistry of the climate system during the last million of years, the relationship between cryo-sphere and sea level, the climate at the scale of geological times, modelling approaches in paleoclimatology, the Precambrian climate, the Phanerozoic climates, the relationship between climate and astronomic cycles, the description and mechanisms of quick climate variability, the Holocene and the anthropogenic perturbation, and the evolution from past climates to future climates

An integrated rock-magnetic and geochemical approach to loess/paleosol sequences from Bohemia and Moravia (Czech Republic): Implications for the Upper Pleistocene paleoenvironment in central Europe

Czech Academy of Sciences Publication Activity Database

Hošek, J.; Hambach, U.; Lisá, Lenka; Matys Grygar, Tomáš; Horáček, I.; Meszner, S.; Knésl, I.

2015-01-01

Roč. 418, 15 January (2015), s. 344-358 ISSN 0031-0182 Institutional support: RVO:67985831 ; RVO:61388980 Keywords : loess/paleosols sequences * rock-magnetism * geochemical proxies * Upper Pleistocene * paleoclimate * Central Europe Subject RIV: DB - Geology ; Mineralogy; DD - Geochemistry (UACH-T) Impact factor: 2.525, year: 2015

Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD

Czech Academy of Sciences Publication Activity Database

Büntgen, Ulf; Myglan, V. S.; Ljungqvist, F. C.; McCormick, M.; Di Cosmo, N.; Sigl, M.; Jungclaus, J.; Wagner, S.; Krusic, P. J.; Esper, J.; Kaplan, J. O.; de Vaan, M. A. C.; Luterbacher, J.; Wacker, L.; Tegel, W.; Kirdyanov, A. V.

2016-01-01

Roč. 9, č. 3 (2016), s. 231-236 ISSN 1752-0894 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : climate science * history * paleoclimate * Antique little ice Subject RIV: EH - Ecology, Behaviour Impact factor: 13.941, year: 2016

Macro fossils vegetable in Palmar formation (later pleistocene) in Entre Rios - Argentina

International Nuclear Information System (INIS)

Ramos, R.; Brea, M.; Krohling, D.

2012-01-01

This work is about the macro fossil knowledge preserved like wood fossils in the El Palmar Formation (Late Pleistocene) from a systematic - anatomical as well as paleoecological and paleoclimate point of view.The paleo Flora comes from various fossil located in the province of Entre Rios - Argentina

Chromium isotope fractionation during coprecipitation with calcium carbonate

DEFF Research Database (Denmark)

Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

The chromium (Cr) isotopic composition of carbonates can potentially be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenvironmental changes, for example related to the rise of oxygen during the Ar...... et al., 2007, Water Air Soil Poll. 179, 381-390. [2] Sánchez-Pastor et al., 2011, Cryst. Growth Des. 11, 3081-3089.......The chromium (Cr) isotopic composition of carbonates can potentially be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenvironmental changes, for example related to the rise of oxygen during...... the Archaean and Protoerozoic, needs careful assessment of the signal robustness and necessitates a thorough understanding of the Cr cycle in Earth system processes. We conducted experiments testing the incorporation and isotopic fractionation of chromate into the calcite lattice. Our experiments indicate...

Using paleoclimate proxy-data to select optimal realisations in an ensemble of simulations of the climate of the past millennium

Energy Technology Data Exchange (ETDEWEB)

Goosse, Hugues [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique G. Lemaitre, Chemin du Cyclotron, 2, 1348, Louvain-la-Neuve (Belgium); Renssen, Hans [Vrije Universiteit Amsterdam, Faculty of Earth and Life Sciences, Amsterdam, HV (Netherlands); Timmermann, Axel [University of Hawaii, IPRC, SOEST, Honolulu, HI (United States); Bradley, Raymond S. [University of Massachusetts, Department of Geosciences, Masschusetts, MA (United States); Mann, Michael E. [Pennsylvania State University, Department of Meteorology and Earth and Environmental Systems Institute (EESI), Pennsylvania, PA (United States)

2006-08-15

We present and describe in detail the advantages and limitations of a technique that combines in an optimal way model results and proxy-data time series in order to obtain states of the climate system consistent with model physics, reconstruction of past radiative forcing and proxy records. To achieve this goal, we select among an ensemble of simulations covering the last millennium performed with a low-resolution 3-D climate model the ones that minimise a cost function. This cost function measures the misfit between model results and proxy records. In the framework of the tests performed here, an ensemble of 30 to 40 simulations appears sufficient to reach reasonable correlations between model results and reconstructions, in configurations for which a small amount of data is available as well as in data-rich areas. Preliminary applications of the technique show that it can be used to provide reconstructions of past large-scale temperature changes, complementary to the ones obtained by statistical methods. Furthermore, as model results include a representation of atmospheric and oceanic circulations, it can be used to provide insights into some amplification mechanisms responsible for past temperature changes. On the other hand, if the number of proxy records is too low, it could not be used to provide reconstructions of past changes at a regional scale. (orig.)

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2002-09-25

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and

Reduction of Burn Progression with Topical Delivery of (Antitumor Necrosis Factor-alpha )-Hyaluronic Acid Conjugates

Science.gov (United States)

2012-01-01

antibody conjugation to HA The conjugation chemistry followed a method previously developed in our laboratory. Briefly, HA (12 mg) was modi - fied...Webster MW, McGill JB, Schwartz SL. Promotion and acceleration of diabetic ulcer healing by arginine-glycine-aspartic acid (RGD) peptide matrix. RGD...Study Group. Diabetes Care 1995; 18: 39–46. 32. Ho-Asjoe M, Chronnell CM, Frame JD, Leigh IM, Carver N. Immunohistochemical analysis of burn depth. J

Lore: Capturing Traditional Environmental Knowledge | CRDI ...

International Development Research Centre (IDRC) Digital Library (Canada)

Martha Johnson a des diplômes en études environnementales et en anthropologie de l'Université de Toronto et de l'Université McGill. Elle a beaucoup travaillé dans le nord du Canada et a déjà été directrice de la recherche à l'Institut culturel déné. À ce titre, elle a été la coordonnatrice du projet pilote conjoint sur le SET ...

Bayesian Models for Streamflow and River Network Reconstruction using Tree Rings

Science.gov (United States)

Ravindranath, A.; Devineni, N.

2016-12-01

Water systems face non-stationary, dynamically shifting risks due to shifting societal conditions and systematic long-term variations in climate manifesting as quasi-periodic behavior on multi-decadal time scales. Water systems are thus vulnerable to long periods of wet or dry hydroclimatic conditions. Streamflow is a major component of water systems and a primary means by which water is transported to serve ecosystems' and human needs. Thus, our concern is in understanding streamflow variability. Climate variability and impacts on water resources are crucial factors affecting streamflow, and multi-scale variability increases risk to water sustainability and systems. Dam operations are necessary for collecting water brought by streamflow while maintaining downstream ecological health. Rules governing dam operations are based on streamflow records that are woefully short compared to periods of systematic variation present in the climatic factors driving streamflow variability and non-stationarity. We use hierarchical Bayesian regression methods in order to reconstruct paleo-streamflow records for dams within a basin using paleoclimate proxies (e.g. tree rings) to guide the reconstructions. The riverine flow network for the entire basin is subsequently modeled hierarchically using feeder stream and tributary flows. This is a starting point in analyzing streamflow variability and risks to water systems, and developing a scientifically-informed dynamic risk management framework for formulating dam operations and water policies to best hedge such risks. We will apply this work to the Missouri and Delaware River Basins (DRB). Preliminary results of streamflow reconstructions for eight dams in the upper DRB using standard Gaussian regression with regional tree ring chronologies give streamflow records that now span two to two and a half centuries, and modestly smoothed versions of these reconstructed flows indicate physically-justifiable trends in the time series.

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

Science.gov (United States)

DiMichele, W.A.; Cecil, C.B.; Montanez, I.P.; Falcon-Lang, H. J.

2010-01-01

Wetland floras narrowly define perceptions of Pennsylvanian tropical ecosystems, the so-called Coal Age. Such wetlands reflect humid to perhumid climate, leading to characterizations of Pennsylvanian tropics as everwet, swampy. These views are biased by the high preservation potential of wetlands. Sedimentation patterns, paleosols, and fossil floras indicate the presence of vegetation tolerant of subhumid to dry-subhumid, perhaps semi-arid climate in basins between peat formation times. Understanding the significance of this seasonally-dry vegetation has suffered from conceptual and terminological confusion. A clearer view has emerged as models for framing the data have improved. Basinal floras typical of seasonally-dry conditions, relatively low soil moisture regimes, are well documented but mainly from isolated deposits. Some of the earliest, dominated by primitive pteridosperms ("Fl??zfern" floras), occur in clastic rocks between European Early Pennsylvanian coal beds. Later Early Pennsylvanian, fern-cordaitalean vegetation, different from coal floras, is preserved in marine goniatite bullions. Conifers are first suggested by late Mississippian Potoniesporites pollen. About the same time, in North America, broadleaf foliage, Lesleya and Megalopteris occur in basin-margin settings, on drought-prone limestone substrates. The best known, xeromorphic floras found between coal beds appear in the Middle through Late Pennsylvanian, containing conifers, cordaitaleans, and pteridosperms. The Middle Pennsylvanian appearances of this flora are mainly allochthonous, though parautochthonous occurrences have been reported. Parautochthonous assemblages are mostly Late Pennsylvanian. The conifer flora became dominant in western and central Pangaean equatorial lowlands in earliest Permian. Location of the humid-perhumid wetland flora during periods of relative dryness, though rarely discussed, is as, or more, perplexing than the spatial location of seasonally-dry floras through

Qualitative and quantitative aspects of pain in lateral posterior thoracotomy patients Aspectos cualitativo y cuantitativo del dolor de pacientes sometidos a la toracotomia postero-lateral Aspectos qualitativo e quantitativo da dor de pacientes submetidos à toracotomia póstero-lateral

Directory of Open Access Journals (Sweden)

Thaiza Teixeira Xavier

2006-10-01

Full Text Available Descriptive study that proposed to compare the qualitative and quantitative behavior of the pain in lateral posterior thoracotomy patients. The sample was consisted of 18 individuals with an average age of 44 years. The instruments used were physiotherapy evaluation form, numerical pain scale and McGill questionnaire for pain. The pain on the numerical pain scale was considered moderate(5 for both sexes. The descriptors of the McGill questionnaire choosen by the patients with higher frequency were: in the sensorial component, beat4, pointed1, shock2, final and pull2; in the afetive component, tired1, bored1, punishald1 and miserable1 and in the evaluative component was flat. The characteristics of pain in the sensorial group were more evidents on male group. No significant statistical difeferences were observed between quantitative answers concerning pain between the men and women. On the qualitative aspects , was observed an predominancy of the same descriptors of pain in afetive component for both sexes. Pain intensity was categorized as moderate. No significant statistical difference were observed between the pain on the post-operatory lateral posterior thoracotomy. These data demonstrate a necessity for an analysis with a larger study group.Estudio descriptivo que ha determinado comparar el comportamiento cualitativo y cuantitativo del dolor en pacientes sometidos a la Toracotomia Postero Lateral(TPL. La muestra fue constituida por 18 (dieciocho individuos, siendo 10 (diez hombres y 8 (ocho mujeres con edad media de 44 años. Como instrumento se utilizo la ficha de evaluacion fisioterapeutica, escala numerica moderada(5 para ambos los sexos. Los descriptores de los cuestionarios para dolor McGill escogidos con mayor frecuencia por los pacientes fueron: en el componente sensorial pungente4, puntada1, choque2, fina1, tirãn2; en el componente afectivo, cansacial1, mareante1, castigante1 y miserable1 y en el componente evaluativo fue pesada1

Evaluation of proxy-based millennial reconstruction methods

Energy Technology Data Exchange (ETDEWEB)

Lee, Terry C.K.; Tsao, Min [University of Victoria, Department of Mathematics and Statistics, Victoria, BC (Canada); Zwiers, Francis W. [Environment Canada, Climate Research Division, Toronto, ON (Canada)

2008-08-15

A range of existing statistical approaches for reconstructing historical temperature variations from proxy data are compared using both climate model data and real-world paleoclimate proxy data. We also propose a new method for reconstruction that is based on a state-space time series model and Kalman filter algorithm. The state-space modelling approach and the recently developed RegEM method generally perform better than their competitors when reconstructing interannual variations in Northern Hemispheric mean surface air temperature. On the other hand, a variety of methods are seen to perform well when reconstructing surface air temperature variability on decadal time scales. An advantage of the new method is that it can incorporate additional, non-temperature, information into the reconstruction, such as the estimated response to external forcing, thereby permitting a simultaneous reconstruction and detection analysis as well as future projection. An application of these extensions is also demonstrated in the paper. (orig.)

The role of clouds and oceans in global greenhouse warming

International Nuclear Information System (INIS)

Hoffert, M.I.

1992-12-01

During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, ''Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature''. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact approximate to 12,800 Years Ago. 1. Ice Cores and Glaciers

Czech Academy of Sciences Publication Activity Database

Wolbach, W. S.; Ballard, J. P.; Mayewski, P. A.; Adedeji, V.; Bunch, T. E.; Firestone, R. B.; French, T. A.; Howard, G. A.; Israde-Alcántara, I.; Johnson, J. R.; Kimbel, D. R.; Kinzie, Ch. R.; Kurbatov, A.; Kletetschka, Günther; LeCompte, M. A.; Mahaney, W. C.; Mellot, A. L.; Maiorana-Boutilier, A.; Mitra, S.; Moore, Ch. R.; Napier, W. M.; Parlier, J.; Tankersley, K. B.; Thomas, B. C.; Wittke, J. H.; West, A.; Kennett, J. P.

2018-01-01

Roč. 126, č. 2 (2018), s. 165-184 ISSN 0022-1376 Institutional support: RVO:67985831 Keywords : biomass burning * comet * deposition * ice core * impact * mass extinction * paleoclimate * paleoenvironment * platinum * trigger mechanism * wildfire * winter * Younger Dryas Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 1.952, year: 2016

Impact of non-adherent Ibuprofen foam dressing in the lives of patients with venous ulcers.

Science.gov (United States)

Salomé, Geraldo Magela; Ferreira, Lydia Masako

2017-01-01

to evaluate pain in patients with lower limb venous ulcer who used non-adherent Ibuprofen foam dressing (IFD). we conducted a prospective study of patients with lower limb venous ulcers treated from April 2013 to August 2014. We used the Numerical Scale and McGill Pain Questionnaire, performing the assessments at the moment of inclusion of the patient in the study and every eight days thereafter, totaling five consultations. We divided the patients into two groups: 40 in the Study Group (SG), who were treated with IFD, and 40 in the Control Group (CG), treated with primary dressing, according to tissue type and exudate. at the first consultation, patients from both groups reported intense pain. On the fifth day, SG patients reported no pain and the majority of CG reported moderate pain. Regarding the McGill Pain Questionnaire, most patients of both groups reported sensations related to sensory, affective, evaluative and miscellaneous descriptors at the beginning of data collection; after the second assessment, there was slight improvement among the patients in the SG. After the third consultation, they no longer reported the mentioned descriptors. CG patients displayed all the sensations of these descriptors until the fifth visit. non-adherent Ibuprofen foam dressing is effective in reducing the pain of patients with venous ulcers. avaliar a dor em pacientes portadores de úlcera venosa de membros inferiores que utilizaram curativo de espuma não aderente com Ibuprofeno (CEI). estudo prospectivo de pacientes portadores de úlceras venosas de membros inferiores tratados no período de abril de 2013 a agosto de 2014. Foram utilizados os questionários Escala Numérica e Questionário de Dor de McGille, as avaliações eram feitas no momento da inclusão do paciente no estudo e a cada oito dias, totalizando cinco consultas. Os pacientes foram divididos em dois grupos: 40 no Grupo Estudo (GE), que foram tratados com CEI, e 40 no Grupo Controle (GC), tratados com

Latitude, sunshine, and human lactase phenotype distributions may contribute to geographic patterns of modern disease: the inflammatory bowel disease model

Directory of Open Access Journals (Sweden)

Szilagyi A

2014-05-01

Full Text Available Andrew Szilagyi,1 Henry Leighton,2 Barry Burstein,3 Xiaoqing Xue41Division of Gastroenterology, Department of Medicine, Jewish General Hospital, 2Department of Atmospheric and Oceanic Sciences, 3Department of Medicine, Jewish General Hospital, 4Department of Emergency Medicine, Jewish General Hospital, McGill University, Montreal, QC, CanadaAbstract: Countries with high lactase nonpersistence (LNP or low lactase persistence (LP populations have lower rates of some “western” diseases, mimicking the effects of sunshine and latitude. Inflammatory bowel disease (IBD, ie, Crohn's disease and ulcerative colitis, is putatively also influenced by sunshine. Recent availability of worldwide IBD rates and lactase distributions allows more extensive comparisons. The aim of this study was to evaluate the extent to which modern day lactase distributions interact with latitude, sunshine exposure, and IBD rates. National IBD rates, national distributions of LP/LNP, and population-weighted average national annual ultraviolet B exposure were obtained, estimated, or calculated from the literature. Negative binomial analysis was used to assess the relationship between the three parameters and IBD rates. Analyses for 55 countries were grouped in three geographic domains, ie, global, Europe, and non-Europe. In Europe, both latitude and ultraviolet B exposure correlate well with LP/LNP and IBD. In non-Europe, latitude and ultraviolet B exposure correlate weakly with LP/LNP, but the latter retains a more robust correlation with IBD. In univariate analysis, latitude, ultraviolet B exposure, and LP/LNP all had significant relationships with IBD. Multivariate analysis showed that lactase distributions provided the best model of fit for IBD. The model of IBD reveals the evolutionary effects of the human lactase divide, and suggests that latitude, ultraviolet B exposure, and LP/LNP mimic each other because LP/LNP follows latitudinal directions toward the equator

Late Pliocene - Early Pleistocene paleoenvironmental reconstruction based on stable isotope compositions of Stephanorhinus sp. and Mammut sp. teeth

Science.gov (United States)

Szabó, Péter; Kovács, János; Kocsis, László; Gasparik, Mihály; Vennemann, Torsten; Demény, Attila; Virág, Attila

2014-05-01

Stable isotope measurements of skeletal apatite from herbivorous mammals are often used to provide information on the terrestrial paleoenvironment and paleoclimate. In this study fossil teeth of Stephanorhinus Kretzoi 1942 (rhinoceros) and Mammut Blumenbach 1799 (mastodon), amongst others, were investigated from the Carpathian Basin. According to the biostratigraphy, the age of the samples has a range from Late Pliocene to Early Pleistocene. Reconstructing paleoclimate and paleoenvironment of this era is important as it can be an analogue for the future climate. Oxygen and carbon isotopic compositions were measured from the tooth enamel, because it is believed to be the most resistant to diagenetic alteration (e.g., Kohn & Cerling, 2002). The carbon isotopic composition in the carbonate fraction of apatite can be related to the diet of the animal (Kohn & Cerling, 2002). Hence, it can reflect the photosynthetic pathway (C3 or C4) of the plants consumed by these herbivores. The δ18O values were determined in the phosphate fraction of apatite. In the case of large mammals that are obligate drinkers, the δ18O values closely track those of the environmental water (Bryant & Froelich, 1995). Knowing the δ18O values of environmental water and relating it to local precipitation, the mean annual temperature (MAT) of the site can be calculated (Dansgaard, 1964). The δ13C values range from -10 to -15 o (VPDB). The result clearly shows that these animals consumed C3 plants. Most of the δ13C values indicate mixed grassland-open woodland rather than a closed canopy forest. Although there is variation in the δ18O values (mean 14.2 ± 1.0 o VSMOW, n=17), most of the samples would support a MAT range of 8-12 ° C. This is in good agreement with other proxies for the localities and time period (Kovács et al., 2013). Bryant, D.J. & Froelich, P.N. (1995) A model of oxygen-isotope fractionation in bodywater of large-mammals. Geochimica et Cosmochimica Acta 59, 4523

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

Energy Technology Data Exchange (ETDEWEB)

DiMichele, William A. [National Museum of Natural History MRC-121, Smithsonian Institution, Washington, DC 20560 (United States); Cecil, C. Blaine [National Museum of Natural History MRC-121, Smithsonian Institution, Washington, DC 20560 (United States); U.S. Geological Survey, Reston, VA 20192 (United States); Montanez, Isabel P. [Department of Geology, University of California, Davis, CA 95616 (United States); Falcon-Lang, Howard J. [Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX (United Kingdom)

2010-08-01

Wetland floras narrowly define perceptions of Pennsylvanian tropical ecosystems, the so-called Coal Age. Such wetlands reflect humid to perhumid climate, leading to characterizations of Pennsylvanian tropics as everwet, swampy. These views are biased by the high preservation potential of wetlands. Sedimentation patterns, paleosols, and fossil floras indicate the presence of vegetation tolerant of subhumid to dry-subhumid, perhaps semi-arid climate in basins between peat formation times. Understanding the significance of this seasonally-dry vegetation has suffered from conceptual and terminological confusion. A clearer view has emerged as models for framing the data have improved. Basinal floras typical of seasonally-dry conditions, relatively low soil moisture regimes, are well documented but mainly from isolated deposits. Some of the earliest, dominated by primitive pteridosperms (''Floezfern'' floras), occur in clastic rocks between European Early Pennsylvanian coal beds. Later Early Pennsylvanian, fern-cordaitalean vegetation, different from coal floras, is preserved in marine goniatite bullions. Conifers are first suggested by late Mississippian Potoniesporites pollen. About the same time, in North America, broadleaf foliage, Lesleya and Megalopteris occur in basin-margin settings, on drought-prone limestone substrates. The best known, xeromorphic floras found between coal beds appear in the Middle through Late Pennsylvanian, containing conifers, cordaitaleans, and pteridosperms. The Middle Pennsylvanian appearances of this flora are mainly allochthonous, though parautochthonous occurrences have been reported. Parautochthonous assemblages are mostly Late Pennsylvanian. The conifer flora became dominant in western and central Pangaean equatorial lowlands in earliest Permian. Location of the humid-perhumid wetland flora during periods of relative dryness, though rarely discussed, is as, or more, perplexing than the spatial location of

The Influence of Volcanic Eruptions on the Climate of Tropical South America During the Last Millennium in an Isotope-Enabled General Circulation Model

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Colose, Christopher M.; LeGrande, Allegra N.; Vuille, Mathias

2016-01-01

Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El Niño-Southern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850 CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium. An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records. Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the "amount effect". During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is

Reconstructing paleo-precipitation amounts using a terrestrial hydrologic model: Lake Titicaca and the Salar de Uyuni, Peru and Bolivia

Science.gov (United States)

Nunnery, J. A.; Baker, P. A.; Coe, M. T.; Fritz, S. C.

2010-12-01

The Peruvian/Bolivian Altiplano has provided many information-rich records bearing on the history of the South American summer monsoon (SASM), a large-scale circulation system that is responsible for much of the precipitation over the Amazon basin and the southern tropics and subtropics. Examples of these paleoclimate time series include long, drill core records from Lake Titicaca (extending back to ca. 400 Ka, Fritz et al., 2007), the long drill core record from Salar de Uyuni (> 250 Ka, Baker et al., 2001; Fritz et al., 2004), paleo-lake level records from the Salar de Uyuni (e.g. Bills et al., 2004; Placzek et al, 2006); drill core records from the Rio Desaguadero valley (Rigsby et al., 2003), and ice core records from Quelccaya, Illimani, and Sajama (Thompson et al., 2000; Ramirez et al., 2003). Several previous studies using energy and water balance models have been applied to these records in attempts to provide quantitative constraints on paleo-temperature and paleo-precipitation (e.g. Kessler, 1984; Hastenrath and Kutzbach, 1985; Cross et al, 2001; Rowe and Dunbar, 2004; Arnold, 2002; Blodgett et al., 1997). For example, Blodgett et al. concluded that high paleolake stands in the Bolivian Altiplano, dated at ca. 16,000 cal. Yr BP (Bills et al., 1994) required precipitation 20% higher than modern at temperatures 5°C colder than modern. However, their model did not take into account the major overflow from Lake Titicaca. Using the THMB hydrologic model, we show that overflow from Lake Titicaca is necessary to produce and sustain large lakes in the Salar de Uyuni basin. This hydrological connection (via the Rio Desaguadero) between the northern and southern Altiplano likely was only established about 60,000 years ago. Prior to that, there were no sustained, large and deep paleolakes on the southern Altiplano. Rather, drill core evidence indicates a very long sequence of shallow, hypersaline lakes and playas.

Paleoclimate and bubonic plague: a forewarning of future risk?

Directory of Open Access Journals (Sweden)

McMichael Anthony J

2010-08-01

Full Text Available Abstract Pandemics of bubonic plague have occurred in Eurasia since the sixth century ad. Climatic variations in Central Asia affect the population size and activity of the plague bacterium's reservoir rodent species, influencing the probability of human infection. Using innovative time-series analysis of surrogate climate records spanning 1,500 years, a study in BMC Biology concludes that climatic fluctuations may have influenced these pandemics. This has potential implications for health risks from future climate change. See research article http://www.biomedcentral.com/1741-7007/8/112

Late Cenozoic Arctic Ocean sea ice and terrestrial paleoclimate.

Science.gov (United States)

Carter, L.D.; Brigham-Grette, J.; Marincovich, L.; Pease, V.L.; Hillhouse, J.W.

1986-01-01

Sea otter remains found in deposits of two marine transgressions (Bigbendian and Fishcreekian) of the Alaskan Arctic Coastal Plain which occurred between 2.4 and 3 Ma suggest that during these two events the southern limit of seasonal sea ice was at least 1600 km farther north than at present in Alaskan waters. Perennial sea ice must have been severely restricted or absent, and winters were warmer than at present during these two sea-level highstands. Paleomagnetic, faunal, and palynological data indicate that the later transgression (Fishcreekian) occurred during the early part of the Matuyama Reversed-Polarity Chron. -from Authors

Associations between low back pain, urinary incontinence, and abdominal muscle recruitment as assessed via ultrasonography in the elderly.

Science.gov (United States)

Figueiredo, Vânia F; Amorim, Juleimar S C; Pereira, Aline M; Ferreira, Paulo H; Pereira, Leani S M

2015-01-01

Low back pain (LBP) and urinary incontinence (UI) are highly prevalent among elderly individuals. In young adults, changes in trunk muscle recruitment, as assessed via ultrasound imaging, may be associated with lumbar spine stability. To assess the associations between LBP, UI, and the pattern of transversus abdominis (TrA), internal (IO), and external oblique (EO) muscle recruitment in the elderly as evaluated by ultrasound imaging. Fifty-four elderly individuals (mean age: 72±5.2 years) who complained of LBP and/or UI as assessed by the McGill Pain Questionnaire, Incontinence Questionnaire-Short Form, and ultrasound imaging were included in the study. The statistical analysis comprised a multiple linear regression model, and a p-value recruitment. These results suggest that age-related factors may have interfered with the findings of the study, thus emphasizing the need to perform ultrasound imaging-based studies to measure abdominal muscle recruitment in the elderly.

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact approximate to 12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

Czech Academy of Sciences Publication Activity Database

Wolbach, W. S.; Ballard, J. P.; Mayewski, P. A.; Parnell, A. C.; Cahill, N.; Adedeji, V.; Bunch, T. E.; Dominguez-Vazquez, G.; Erlandson, J. M.; Firestone, R. B.; French, T. A.; Howard, G.; Israde-Alcántara, I.; Johnson, J. R.; Kimbel, D.; Kinzie, Ch. R.; Kurbatov, A.; Kletetschka, Günther; LeCompte, M. A.; Mahaney, W. C.; Mellot, A. L.; Mitra, S.; Maiorana-Boutilier, A.; Moore, Ch. R.; Napier, W. M.; Parlier, J.; Tankersley, K. B.; Thomas, B. C.; Wittke, J. H.; West, A.; Kennett, J. P.

2018-01-01

Roč. 126, č. 2 (2018), s. 185-205 ISSN 0022-1376 Institutional support: RVO:67985831 Keywords : biomass burning * climate feedback * climate variation * ice core * lacustrine deposit * marine sediment * paleoclimate * quantitative analysis * terrestrial deposit * winter * Younger Dryas Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 1.952, year: 2016

Development and Pilot Evaluation of a Novel Dignity-Conserving End-of-Life (EoL) Care Model for Nursing Homes in Chinese Societies.

Science.gov (United States)

Ho, Andy H Y; Dai, Annie A N; Lam, Shu-Hang; Wong, Sandy W P; Tsui, Amy L M; Tang, Jervis C S; Lou, Vivian W Q

2016-06-01

The provision of end-of-life (EoL) care in long-term-care settings remains largely underdeveloped in most Chinese societies, and nursing home residents often fail to obtain good care as they approach death. This paper systematically describes the development and implementation mechanisms of a novel Dignity-Conserving EoL Care model that has been successfully adopted by three nursing homes in Hong Kong and presents preliminary evidence of its effectiveness on enhancing dignity and quality of life (QoL) of terminally ill residents. Nine terminally ill nursing home residents completed the McGill Quality of Life Questionnaire and the Nursing Facilities Quality of Life Questionnaire at baseline and 6 months post-EoL program enrollment. Wilcoxon signed rank test was used to detect significance changes in each QoL domains across time. Although significant deterioration was recorded for physical QoL, significant improvement was observed for social QoL. Moreover, a clear trend toward significant improvements was identified for the QoL domains of individuality and relationships. A holistic and compassionate caring environment, together with the core principles of family-centered care, interagency and interdisciplinary teamwork, as well as cultural-specific psycho-socio-spiritual support, are all essential elements for optimizing QoL and promoting death with dignity for nursing home residents facing morality. This study provides a useful framework to facilitate the future development of EoL care in long-term-care settings in the Chinese context. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Optogenetics in preclinical neuroscience and psychiatry research: recent insights and potential applications

OpenAIRE

Britt, Jonathan; McDevitt,Ross; Reed,Sean

2014-01-01

Ross A McDevitt,1 Sean J Reed,2 Jonathan P Britt2,3 1Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA; 2Integrated Program in Neuroscience, Montreal Neurological Institute, 3Department of Psychology, McGill University, Montreal, QC, Canada Abstract: There have been significant advances in the treatment of psychiatric disease in the last half century, but it is still unclear which neural circuits are ultimately responsible for s...

Gulf War Illness-Evaluation of an Innovative Detoxification Program

Science.gov (United States)

2015-12-01

multidimensional fatigue inventory, the McGill pain questionnaire, the trailmaking test A and B, the grooved pegboard test , the Wechsler memory scale III-a...quality of life forms and took a series of cognitive function tests before and seven days after the sauna therapy. Twenty three of the 31 veterans...completed a three-month follow-up series of tests . Some veterans were in a control group that took all tests , then waited one month before repeating

Management of scientific and engineering data collected during site characterization of a potential high-level waste repository

International Nuclear Information System (INIS)

Newbury, C.M.; Heitland, G.W.

1992-01-01

This paper discusses the characterization of Yucca Mountain as a potential site for a high-level nuclear waste repository encompasses many diverse investigations to determine the nature of the site. Laboratory and on-site investigations are being conducted of the geology, hydrology, mineralogy, paleoclimate, geotechnical properties, and past use of the area, to name a few. Effective use of the data from these investigations requires development of a system for the collection, storage, and dissemination of those scientific and engineering data needed to support model development, design, and performance assessment. The time and budgetary constraints associated with this project make sharing of technical data within the geoscience community absolutely critical to the successful solution of the complex scientific problem challenging us

Climate change research in Canada

International Nuclear Information System (INIS)

Dawson, K.

1994-01-01

The current consensus on climatic change in Canada is briefly summarized, noting the results of modelling of the effects of a doubling of atmospheric CO 2 , the nonuniformity of climate change across the country, the uncertainties in local responses to change, and the general agreement that 2-4 degrees of warming will occur for each doubling of CO 2 . Canadian government response includes programs aimed at reducing the uncertainties in the scientific understanding of climate change and in the socio-economic response to such change. Canadian climate change programs include participation in large-scale experiments on such topics as heat transport in the ocean, and sources and sinks of greenhouse gases; development of next-generation climate models; studying the social and economic effects of climate change in the Great Lakes Basin and Mackenzie River Basin; investigation of paleoclimates; and analysis of climate data for long-term trends

Exploiting the atmosphere's memory for monthly, seasonal and interannual temperature forecasting using Scaling LInear Macroweather Model (SLIMM)

Science.gov (United States)

Del Rio Amador, Lenin; Lovejoy, Shaun

2016-04-01

. The corresponding space-time model (the ScaLIng Macroweather Model (SLIMM) is thus only multifractal in space where the spatial intermittency is associated with different climate zones. SLIMM exploits the power law (scaling) behavior in time of the temperature field and uses the long historical memory of the temperature series to improve the skill. The only model parameter is the fluctuation scaling exponent, H (usually in the range -0.5 - 0), which is directly related to the skill and can be obtained from the data. The results predicted analytically by the model have been tested by performing actual hindcasts in different 5° x 5° regions covering the planet using ERA-Interim, 20CRv2 and NCEP/NCAR reanalysis as reference datasets. We report maps of theoretical skill predicted by the model and we compare it with actual skill based on hindcasts for monthly, seasonal and annual resolutions. We also present maps of calibrated probability hindcasts with their respective validations. Comparisons between our results using SLIMM, some other stochastic autoregressive model, and hindcasts from the Canadian Seasonal to Interannual Prediction System (CanSIPS) and the National Centers for Environmental Prediction (NCEP)'s model CFSv2, are also shown. For seasonal temperature forecasts, SLIMM outperforms the GCM based forecasts in over 90% of the earth's surface. SLIMM forecasts can be accessed online through the site: http://www.to_be_announced.mcgill.ca.

3D Volume and Morphology of Perennial Cave Ice and Related Geomorphological Models at Scăriloara Ice Cave, Romania, from Structure from Motion, Ground Penetrating Radar and Total Station Surveys

Science.gov (United States)

Hubbard, J.; Onac, B. P.; Kruse, S.; Forray, F. L.

2017-12-01

Research at Scăriloara Ice Cave has proceeded for over 150 years, primarily driven by the presence and paleoclimatic importance of the large perennial ice block and various ice speleothems located within its galleries. Previous observations of the ice block led to rudimentary volume estimates of 70,000 to 120,000 cubic meters (m3), prospectively placing it as one of the world's largest cave ice deposits. The cave morphology and the surface of the ice block are now recreated in a total station survey-validated 3D model, produced using Structure from Motion (SfM) software. With the total station survey and the novel use of ArcGIS tools, the SfM validation process is drastically simplified to produce a scaled, georeferenced, and photo-texturized 3D model of the cave environment with a root-mean-square error (RMSE) of 0.24 m. Furthermore, ground penetrating radar data was collected and spatially oriented with the total station survey to recreate the ice block basal surface and was combined with the SfM model to create a model of the ice block itself. The resulting ice block model has a volume of over 118,000 m3 with an uncertainty of 9.5%, with additional volumes left un-surveyed. The varying elevation of the ice block basal surface model reflect specific features of the cave roof, such as areas of enlargement, shafts, and potential joints, which offer further validation and inform theories on cave and ice genesis. Specifically, a large depression area was identified as a potential area of initial ice growth. Finally, an ice thickness map was produced that will aid in the designing of future ice coring projects. This methodology presents a powerful means to observe and accurately characterize and measure cave and cave ice morphologies with ease and affordability. Results further establish the significance of Scăriloara's ice block to paleoclimate research, provide insights into cave and ice block genesis, and aid future study design.

Spring temperature responses of oaks are synchronous with North Atlantic conditions during the last deglaciation

Science.gov (United States)

Steven L. Voelker; Paul-Emile Noirot-Cosson; Michael C. Stambaugh; Erin R. McMurry; Frederick C. Meinzer; Barbara Lachenburch; Richard P. Guyette

2012-01-01

Paleoclimate proxies based on the measurement of xylem cell anatomy have rarely been developed across the temperature range of a species or applied to wood predating the most recent millennium. Here we describe wood anatomy-based proxies for spring temperatures in central North America from modern bur oaks (Quercus macrocarpa Michx.). The strong...

Effect of the greenhouse gases (CO2, H2O, SO2) on Martian paleoclimate

Science.gov (United States)

Postawko, S. E.; Kuhn, W. R.

1986-01-01

There is general agreement that certain surface features on Mars are indicative of the presence of liquid water at various times in the geologic past. In particular, the valley networks are difficult to explain by a mechanism other than the flow of liquid water. It has been suggested in several studies that a thick CO2 atmosphere on Mars early in its history could have provided a greenhouse warming that would have allowed the flow of water either on the surface or just below the surface. However, this effect was examined with a detailed radiation model, and it was found that if reduced solar luminosity early in the history of the solar system is taken into account, even three bars of CO2 will not provide sufficient greeenhouse warming. The addition of water vapor and sulflur dioxide (both plausible gases that may have been emitted by Martian volcanoes) to the atmosphere also fail to warm the surface above 273 K for reduced solar luminosity conditions. The increase in temperature may be large enough, however, for the formation of these features by brines.

Calibration of amino acid racemization (AAR) kinetics in United States mid-Atlantic Coastal Plain Quaternary mollusks using 87Sr/ 86Sr analyses: Evaluation of kinetic models and estimation of regional Late Pleistocene temperature history

Science.gov (United States)

Wehmiller, J.F.; Harris, W.B.; Boutin, B.S.; Farrell, K.M.

2012-01-01

The use of amino acid racemization (AAR) for estimating ages of Quaternary fossils usually requires a combination of kinetic and effective temperature modeling or independent age calibration of analyzed samples. Because of limited availability of calibration samples, age estimates are often based on model extrapolations from single calibration points over wide ranges of D/L values. Here we present paired AAR and 87Sr/ 86Sr results for Pleistocene mollusks from the North Carolina Coastal Plain, USA. 87Sr/ 86Sr age estimates, derived from the lookup table of McArthur et al. [McArthur, J.M., Howarth, R.J., Bailey, T.R., 2001. Strontium isotopic stratigraphy: LOWESS version 3: best fit to the marine Sr-isotopic curve for 0-509 Ma and accompanying Look-up table for deriving numerical age. Journal of Geology 109, 155-169], provide independent age calibration over the full range of amino acid D/L values, thereby allowing comparisons of alternative kinetic models for seven amino acids. The often-used parabolic kinetic model is found to be insufficient to explain the pattern of racemization, although the kinetic pathways for valine racemization and isoleucine epimerization can be closely approximated with this function. Logarithmic and power law regressions more accurately represent the racemization pathways for all amino acids. The reliability of a non-linear model for leucine racemization, developed and refined over the past 20 years, is confirmed by the 87Sr/ 86Sr age results. This age model indicates that the subsurface record (up to 80m thick) of the North Carolina Coastal Plain spans the entire Quaternary, back to ???2.5Ma. The calibrated kinetics derived from this age model yield an estimate of the effective temperature for the study region of 11??2??C., from which we estimate full glacial (Last Glacial Maximum - LGM) temperatures for the region on the order of 7-10??C cooler than present. These temperatures compare favorably with independent paleoclimate information

Results of PMIP2 coupled simulations of the Mid-Holocene and Last Glacial Maximum – Part 1: experiments and large-scale features

Directory of Open Access Journals (Sweden)

Y. Zhao

2007-06-01

Full Text Available A set of coupled ocean-atmosphere simulations using state of the art climate models is now available for the Last Glacial Maximum and the Mid-Holocene through the second phase of the Paleoclimate Modeling Intercomparison Project (PMIP2. This study presents the large-scale features of the simulated climates and compares the new model results to those of the atmospheric models from the first phase of the PMIP, for which sea surface temperature was prescribed or computed using simple slab ocean formulations. We consider the large-scale features of the climate change, pointing out some of the major differences between the different sets of experiments. We show in particular that systematic differences between PMIP1 and PMIP2 simulations are due to the interactive ocean, such as the amplification of the African monsoon at the Mid-Holocene or the change in precipitation in mid-latitudes at the LGM. Also the PMIP2 simulations are in general in better agreement with data than PMIP1 simulations.

The impact of decongestive physical therapy and elastic bandaging on the control of pain in patients with venous ulcers

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GERALDO MAGELA SALOMÉ

2018-03-01

Full Text Available ABSTRACT Objective: to evaluate pain in individuals with venous ulcers treated with elastic bandage and decongestant physical therapy. Methods: we studied 90 patients, divided into three groups with 30 patients each: a group treated with elastic bandage and decongestant physical therapy; a group treated with elastic bandage; and a group treated only with primary dressing according to tissue type and presence of exudate. We used the Pain Numerical Scale to quantify pain intensity and the McGill Pain Questionnaire for pain qualitative assessment. Results: in the first evaluation, all patients who participated in the study reported intense pain. In the fifth evaluation, the majority of patients treated with elastic bandaging and decongestant physical therapy did not report pain; the majority of patients in the elastic bandage group reported mild pain; and most patients treated only with primary dressing reported mild to moderate pain. During all five assessments using the McGill questionnaire, most patients in the elastic bandaging and primary dressing groups used descriptors of the sensory, affective, evaluative and miscellaneous groups to describe their pain. However, in the fourth and fifth evaluations, most patients who received decongestant physical therapy combined with elastic bandaging treatment did not use any of the descriptors. Conclusion: patients treated with decongestant physical therapy and elastic bandage presented pain improvement from the third evaluation performed on.

Impact of non-adherent Ibuprofen foam dressing in the lives of patients with venous ulcers

Directory of Open Access Journals (Sweden)

GERALDO MAGELA SALOMÉ

Full Text Available ABSTRACT Objective : to evaluate pain in patients with lower limb venous ulcer who used non-adherent Ibuprofen foam dressing (IFD. Methods : we conducted a prospective study of patients with lower limb venous ulcers treated from April 2013 to August 2014. We used the Numerical Scale and McGill Pain Questionnaire, performing the assessments at the moment of inclusion of the patient in the study and every eight days thereafter, totaling five consultations. We divided the patients into two groups: 40 in the Study Group (SG, who were treated with IFD, and 40 in the Control Group (CG, treated with primary dressing, according to tissue type and exudate. Results : at the first consultation, patients from both groups reported intense pain. On the fifth day, SG patients reported no pain and the majority of CG reported moderate pain. Regarding the McGill Pain Questionnaire, most patients of both groups reported sensations related to sensory, affective, evaluative and miscellaneous descriptors at the beginning of data collection; after the second assessment, there was slight improvement among the patients in the SG. After the third consultation, they no longer reported the mentioned descriptors. CG patients displayed all the sensations of these descriptors until the fifth visit. Conclusion : non-adherent Ibuprofen foam dressing is effective in reducing the pain of patients with venous ulcers.

Short term effects of kinesio taping on pain and functional disability in young females with menstrual low back pain: A randomised control trial study.

Science.gov (United States)

Forozeshfard, Mohammad; Bakhtiary, Amir Hoshang; Aminianfar, Atefeh; Sheikhian, Sajedeh; Akbarzadeh, Zeinab

2016-11-21

Menstrual low back pain (LBP) in young females can reduce daily activity and cause functional disability, while the progressive application of kinesio-taping (KT) on pain reduction and functional correction has been stated. This study has been designed to investigate the efficacy of the lumbar vertebral column KT in young female with menstrual LBP. Thirty-two young females with menstrual LBP participated in this crossover study and were assigned randomly in two separate groups. The first group received KT during their first menstrual cycle and No-KT in their next menstrual, while the other group had no KT during the first mentrual cycle and received KT during the next menstrual cycle. The primary outcome measurements included the visual analogue scale (VAS) of pain, Oswestry disability index and McGill pain questionnaire score which were planned to collect at the end of the third day of the menstrual cycle. Comparing pain and disability between two conditions, of menstrual cycle with KT and menstrual cycle without KT, revealed significant reduction in VAS (mean change = 1.7; 95%CI = 0.6 to 2.8; P= 0.005), McGill pain score (mean change = 20.1; 95%CI = 8.7 to 31.3; P= 0.001) and functional disability (mean change = 12.3; 95%CI = 7.2 to 17.5; Pkinesiotaping in young females with menstrual LBP.

Supplement of: The Influence of Volcanic Eruptions on the Climate of Tropical South America During the Last Millennium in an Isotope-Enabled General Circulation Model

Science.gov (United States)

Colose, Christopher; LeGrande, Allegra N.; Vuille, Mathias

2016-01-01

Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El NioSouthern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium.An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records.Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the amount effect. During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is larger

Efficacy of Mindfulness-Based Cognitive Therapy on Late Post-Treatment Pain in Women Treated for Primary Breast Cancer: A Randomized Controlled Trial.

Science.gov (United States)

Johannsen, Maja; O'Connor, Maja; O'Toole, Mia Skytte; Jensen, Anders Bonde; Højris, Inger; Zachariae, Robert

2016-10-01

To assess the efficacy of mindfulness-based cognitive therapy (MBCT) for late post-treatment pain in women treated for primary breast cancer. A randomized wait list-controlled trial was conducted with 129 women treated for breast cancer reporting post-treatment pain (score ≥ 3 on pain intensity or pain burden assessed with 10-point numeric rating scales). Participants were randomly assigned to a manualized 8-week MBCT program or a wait-list control group. Pain was the primary outcome and was assessed with the Short Form McGill Pain Questionnaire 2 (SF-MPQ-2), the Present Pain Intensity subscale (the McGill Pain Questionnaire), and perceived pain intensity and pain burden (numeric rating scales). Secondary outcomes were quality of life (World Health Organization-5 Well-Being Index), psychological distress (the Hospital Depression and Anxiety Scale), and self-reported use of pain medication. All outcome measures were assessed at baseline, postintervention, and 3-month and 6-month follow-up. Treatment effects were evaluated with mixed linear models. Statistically significant time × group interactions were found for pain intensity (d = 0.61; P = .002), the Present Pain Intensity subscale (d = 0.26; P = .026), the SF-MPQ-2 neuropathic pain subscale (d = 0.24; P = .036), and SF-MPQ-2 total scores (d = 0.23; P = .036). Only pain intensity remained statistically significant after correction for multiple comparisons. Statistically significant effects were also observed for quality of life (d = 0.42; P = .028) and nonprescription pain medication use (d = 0.40; P = .038). None of the remaining outcomes reached statistical significance. MBCT showed a statistically significant, robust, and durable effect on pain intensity, indicating that MBCT may be an efficacious pain rehabilitation strategy for women treated for breast cancer. In addition, the effect on neuropathic pain, a pain type reported by women treated for breast cancer, further suggests the potential of MBCT but

Nano-structured calcite produced by micro-organisms in ancient and modern loess in Chinese Loess Plateau

Science.gov (United States)

Xu, H.; Chen, T.; Lu, H.; Wang, X.

2005-12-01

The results from transmission electron microscopy (TEM) and field emission gun scanning microscopy (FEG-SEM) investigation show that there are calcite nano-fibers (CNFs) formed during pedogenic process. The CNFs are widely distributed in the loess and red clay samples of Caoxian, Luochuan, Lingtai, Lantian, and Xifeng profiles as well as the samples of modern surface loess soils in Chinese Loess Plateau. Diameters of all the NFCs are about 40 nm, the length of the CNFs ranges from tens nanometer to several micrometers. Elongation direction of NFCs is unusual near parallel (105)* or (115)*. Crystals of NFCs arrange as bird net like and lattice-like frameworks. X-ray EDS spectra show the weak peaks of magnesium, phosphorous, and sulfur. Our investigation indicates that CNFs are in pore space of loess and paleosol and made up most of carbonate except for caliche nodular layers. Concentration of NFCs in the loess layers are significantly higher than those of paleosol layers because of leaching of carbonate in the paleosol forming environment (warn and wet paleoclimate). The "nanobacteria-like CNFs are well crystalline calcite single crystals with smoothes surfaces. The morphologies of CNFs are very unusual and different from the calcite single crystals observed in most geological environments. The CNFs are directly related to microbial activities in both ancient and modern loess. It is proposed that the intervention of organic compounds derived from microbial activities control the formation of the calcite nano-fibers. Both morphology and bulk composition of CNFs indicate that the formation of the CNFs involves bio-organics derived from microorganisms in loess deposit environment. Formation conditions of the calcite nano-fibers may information about paleoclimate, paleo-environment and paleoecology. So, the discovery of CNFs in loess-paloesol sequences can provide a new route for reconstruct paleoclimate by oxygen and carbon isotope from the CNFs.

Postglacial Records of Southern Hemisphere Westerly Wind Variability From the New Zealand Subantarctic Auckland Islands

Science.gov (United States)

Moy, C. M.; Vandergoes, M.; Gilmer, G. J.; Nichols, J. E.; Dagg, B. J.; Wilson, G. S.; Browne, I. M.; Curtin, L. G.; Aebig, C.; McGlone, M.

2015-12-01

The strength and latitudinal position of the Southern Hemisphere westerly winds (SHWW) play a fundamental role in influencing mid latitude climate and carbon dioxide exchange between the Southern Ocean and the atmosphere. Despite their importance, our understanding of past changes in the SHWW is limited by few paleoclimate records from the modern wind maximum that are often not in agreement. The New Zealand subantarctic Auckland Islands are located within the core of the modern wind belt (50°S) where the ocean-atmospheric linkages between the Antarctic and middle latitudes are strong. In contrast to other subantarctic islands on the Campbell Plateau, the Auckland Islands have protected fjord sub-basins, deep lakes, and peatlands that are advantageous for the development of high-resolution paleoclimate records. We will present ongoing work towards the establishment of multi-proxy and multi-site reconstructions of past SHWW variability from the Auckland Islands. Modern process and paleoclimate results from two research cruises in 2014 and 2015 suggest that in lacustrine and fjord settings, the degree of water column mixing, the stable isotopic composition of n-alkanes and benthic foraminifera, the influx of terrestrial organic matter are good indicators of wind-induced mixing of the water column or precipitation-driven erosion within catchments. In ombrotrophic peatlands, hydrogen isotope ratios of specific organic molecules allow reconstructions of the hydrogen isotope ratios of precipitation, which is related to precipitation source area and the latitudinal position of the SHWW. Using macrofossil counts paired with abundances of leaf wax biomarkers, we are able to estimate the moisture balance at peatland coring sites. Early results indicate an overall strengthening of the SHWW at the Auckland Islands through the Holocene. We will discuss these results within the context of complimentary records developed from New Zealand and southern South America to ultimately

Analysis on metallogenetic geological and physicochemical conditions in uranium deposit No.138

International Nuclear Information System (INIS)

Tang Qitao

1996-01-01

The uranium deposit No.138 is of Mesozoic volcano-sedimentary transformation type. This paper discusses such geological conditions as source of uranium, stratigraphy and lithology, lithofacies and paleogeography, paleoclimate, structure and reworking-regeneration, and such physicochemical conditions as uranium adsorbent and reductant, effective porosity, chemical compositions, pH and Eh of rocks in the deposit

Middle Pleniglacial pedogenesis on the northwestern edge of the Carpathian basin: A multidisciplinary investigation of the Bíňa pedo-sedimentary section, SW Slovakia

Czech Academy of Sciences Publication Activity Database

Hošek, J.; Lisá, Lenka; Hambach, U.; Petr, L.; Vejrostová, L.; Bajer, A.; Matys Grygar, Tomáš; Moska, P.; Gottvald, Z.; Horsák, M.

2017-01-01

Roč. 487, 1 December 2017 (2017), s. 321-339 ISSN 0031-0182 Institutional support: RVO:67985831 ; RVO:61388980 Keywords : loess-paleosol sequence * MIS 3 * erosion/sedimentation * soil micromorphology * pedostratigraphy * paleoclimate Subject RIV: DG - Athmosphere Sciences, Meteorology; DB - Geology ; Mineralogy (UACH-T) OBOR OECD: Climatic research; Geology (UACH-T) Impact factor: 2.578, year: 2016

Lectures on the nearest neighbor method

CERN Document Server

Biau, Gérard

2015-01-01

This text presents a wide-ranging and rigorous overview of nearest neighbor methods, one of the most important paradigms in machine learning. Now in one self-contained volume, this book systematically covers key statistical, probabilistic, combinatorial and geometric ideas for understanding, analyzing and developing nearest neighbor methods. Gérard Biau is a professor at Université Pierre et Marie Curie (Paris). Luc Devroye is a professor at the School of Computer Science at McGill University (Montreal).   .

Sleep quality in subjects suffering from chronic pain

OpenAIRE

Keilani, Mohammad; Crevenna, Richard; Dorner, Thomas Ernst

2017-01-01

Summary Background Sleeping problems are very common in patients with chronic pain. The aim of the study was to investigate the association between different dimensions of chronic pain and sleep quality in chronic pain patients. Methods In this cross-sectional interview-based questionnaire study, patients from 3 different pain treatment centers in Vienna aged 18–65 years, with pain lasting 3 months or longer were asked to participate. The association between the short-form McGill pain questio...

Synthesis on Quaternary aeolian research in the unglaciated eastern United States

Science.gov (United States)

Markewich, Helaine Walsh; Litwin, Ronald J.; Wysocki, Douglas A.; Pavich, Milan J.

2015-01-01

Late-middle and late Pleistocene, and Holocene, inland aeolian sand and loess blanket >90,000 km2 of the unglaciated eastern United States of America (USA). Deposits are most extensive in the Lower Mississippi Valley (LMV) and Atlantic Coastal Plain (ACP), areas presently lacking significant aeolian activity. They provide evidence of paleoclimate intervals when wind erosion and deposition were dominant land-altering processes. This study synthesizes available data for aeolian sand deposits in the LMV, the Eastern Gulf Coastal Plain (EGCP) and the ACP, and loess deposits in the Middle Atlantic Coastal Plain (MACP). Data indicate: (a) the most recent major aeolian activity occurred in response to and coincident with growth and decay of the Laurentide Ice Sheet (LIS); (b) by ∼40 ka, aeolian processes greatly influenced landscape evolution in all three regions; (c) aeolian activity peaked in OIS2; (d) OIS3 and OIS2 aeolian records are in regional agreement with paleoecological records; and (e) limited aeolian activity occurred in the Holocene (EGCP and ACP). Paleoclimate and atmospheric-circulation models (PCMs/ACMs) for the last glacial maximum (LGM) show westerly winter winds for the unglaciated eastern USA, but do not resolve documented W and SW winds in the SEACP and WNW and N winds in the MACP. The minimum areal extent of aeolian deposits in the EGCP and ACP is ∼10,000 km2. For the LMV, it is >80,000 km2. Based on these estimates, published PCMs/ACMs likely underrepresent the areal extent of LGM aeolian activity, as well as the extent and complexity of climatic changes during this interval.

Synthesis on Quaternary aeolian research in the unglaciated eastern United States

Science.gov (United States)

Markewich, Helaine W.; Litwin, Ronald J.; Wysocki, Douglas A.; Pavich, Milan J.

2015-06-01

Late-middle and late Pleistocene, and Holocene, inland aeolian sand and loess blanket >90,000 km2 of the unglaciated eastern United States of America (USA). Deposits are most extensive in the Lower Mississippi Valley (LMV) and Atlantic Coastal Plain (ACP), areas presently lacking significant aeolian activity. They provide evidence of paleoclimate intervals when wind erosion and deposition were dominant land-altering processes. This study synthesizes available data for aeolian sand deposits in the LMV, the Eastern Gulf Coastal Plain (EGCP) and the ACP, and loess deposits in the Middle Atlantic Coastal Plain (MACP). Data indicate: (a) the most recent major aeolian activity occurred in response to and coincident with growth and decay of the Laurentide Ice Sheet (LIS); (b) by ∼40 ka, aeolian processes greatly influenced landscape evolution in all three regions; (c) aeolian activity peaked in OIS2; (d) OIS3 and OIS2 aeolian records are in regional agreement with paleoecological records; and (e) limited aeolian activity occurred in the Holocene (EGCP and ACP). Paleoclimate and atmospheric-circulation models (PCMs/ACMs) for the last glacial maximum (LGM) show westerly winter winds for the unglaciated eastern USA, but do not resolve documented W and SW winds in the SEACP and WNW and N winds in the MACP. The minimum areal extent of aeolian deposits in the EGCP and ACP is ∼10,000 km2. For the LMV, it is >80,000 km2. Based on these estimates, published PCMs/ACMs likely underrepresent the areal extent of LGM aeolian activity, as well as the extent and complexity of climatic changes during this interval.

Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

Science.gov (United States)

Marzen, Rachel; DeNinno, Lauren H.; Cronin, Thomas M.

2016-01-01

Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

Towards community-driven paleogeographic reconstructions: integrating open-access paleogeographic and paleobiology data with plate tectonics

Directory of Open Access Journals (Sweden)

N. Wright

2013-03-01

Full Text Available A variety of paleogeographic reconstructions have been published, with applications ranging from paleoclimate, ocean circulation and faunal radiation models to resource exploration; yet their uncertainties remain difficult to assess as they are generally presented as low-resolution static maps. We present a methodology for ground-truthing the digital Palaeogeographic Atlas of Australia by linking the GPlates plate reconstruction tool to the global Paleobiology Database and a Phanerozoic plate motion model. We develop a spatio-temporal data mining workflow to validate the Phanerozoic Palaeogeographic Atlas of Australia with paleoenvironments derived from fossil data. While there is general agreement between fossil data and the paleogeographic model, the methodology highlights key inconsistencies. The Early Devonian paleogeographic model of southeastern Australia insufficiently describes the Emsian inundation that may be refined using biofacies distributions. Additionally, the paleogeographic model and fossil data can be used to strengthen numerical models, such as the dynamic topography and the associated inundation of eastern Australia during the Cretaceous. Although paleobiology data provide constraints only for paleoenvironments with high preservation potential of organisms, our approach enables the use of additional proxy data to generate improved paleogeographic reconstructions.

Spatial variability and trends in Younger Dryas equilibrium line altitudes across the European Alps using a hypsometrically based ELA model: results and implications

Science.gov (United States)

Keeler, D. G.; Rupper, S.; Schaefer, J. M.; Finkel, R. C.; Maurer, J. M.

2016-12-01

Alpine glaciers constitute an important component of terrestrial paleoclimate records due to, among other characteristics, their high sensitivity to climate change, near global extent, and their integration of myriad climate variables into a single, easily detected signal. Because the glacier equilibrium line altitude (ELA) provides a more explicit representation of climate than many other glacier properties, ELA methods allow for more direct comparisons of multiple glaciers within or between regions. Such comparisons allow for more complete investigations of the ultimate causes of mountain glaciation during specific events. Many studies however tend to focus on a limited number of sites, and employ a large variety of different techniques for ELA reconstruction between studies, making wider climate implications more tenuous. Methods of ELA reconstruction that can be rapidly and consistently applied to an arbitrary number of paleo-glaciers would provide a more accurate portrayal of the changes in climate across a given region. Here we present ELA reconstructions from Egesen Stadial moraines across the European Alps using an ELA model accounting for differences in glacier width, glacier shape, bed topography, ice thickness, and glacier length, including several glaciers constrained to the Younger Dryas using surface exposure dating techniques. We compare reconstructed Younger Dryas ELA values to modern ELA values using the same model, or using end of summer snowline estimates where no glacier is currently present. We further provide uncertainty estimates on the ΔELA using bootstrapped Monte Carlo simulations for the various input parameters. Preliminary results compare favorably to previous glacier studies of the European Younger Dryas, but provide greater context from many glaciers across the region as a whole. Such results allow for a more thorough investigation of the spatial variability and trends in climate during the Younger Dryas across the European Alps, and

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2003-09-25

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling that utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 3 of the project has been reservoir characterization, 3-D modeling, testing of the geologic-engineering model, and technology transfer. This effort has included six tasks: (1) the study of seismic attributes, (2) petrophysical characterization, (3) data integration, (4) the building of the geologic-engineering model, (5) the testing of the geologic-engineering model and (6) technology transfer. This work was scheduled for completion in Year 3. Progress on the project is as follows: geoscientific reservoir characterization is completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been completed. Observations regarding the diagenetic

Knowledge Transfer and Dissemination of Advanced Practice Nursing Information and Research to Acute-Care Administrators.

Science.gov (United States)

Carter, Nancy; Dobbins, Maureen; Peachey, Gladys; Hoxby, Heather; Ireland, Sandra; Akhtar-Danesh, Noori; DiCenso, Alba

2014-03-01

The objective of this study was to ascertain the information needs and knowledge-dissemination preferences of acute-care administrators with respect to advanced practice nursing (APN). Supportive leadership is imperative for the success of APN roles and administrators need up-to-date research evidence and information, but it is unclear what the information needs of administrators are and how they prefer to receive the information. A survey tool was developed from the literature and from the findings of a qualitative study with acute-care leaders. Of 107 surveys distributed to nursing administrators in 2 teaching hospitals, 79 (73.8%) were returned. Just over half of respondents reported wanting APN information related to model of care and patient and systems outcomes of APN care; the majority expressed a preference for electronic transmission of the information. Researchers need multiple strategies for distributing context-specific APN evidence and information to nursing administrators. Copyright© by Ingram School of Nursing, McGill University.

A 150 kyr-long hydroclimate record from Southern California using Searles Lake sediments: initial findings

Science.gov (United States)

Stroup, J. S.; Olson, K. J.; McGee, D.; Lowenstein, T. K.; Smoot, J. P.; Janick, J. J.; Lund, S.; Peaple, M.; Chen, C. Y.; Feakins, S. J.; Litwin, R.

2017-12-01

Over decadal to millennial scales, the southwestern U.S has experienced large shifts in hydroclimate ranging from pluvial conditions to extreme droughts. Direct observations, modeling and proxy data suggest precipitation amount and distribution are controlled by multiple factors including the position of the Hadley Cell, strength of the Aleutian Low and North Pacific High, ENSO and the path of winter storm tracks. Sediment records from closed basin lakes provide a means for assessing how hydrologic conditions have responded to past climate changes; however, long (>50 ka) paleoclimate records from lakes are rare and high-resolution age models are challenging to obtain. Searles Lake, in southeastern California, contains a sedimentary record that spans from the Holocene to the Pliocene at high resolution. Previous drill core studies from the basin used stratigraphy and sediment mineralogy to interpret paleoenvironmental changes and have demonstrated that the lake's sediments are able to be precisely dated. These results provide a strong foundation for new high-resolution investigations of the lake sediments. In January 2017, our group collected a new 80 m-long core with the aim of reconstructing hydrologic changes over the last 150 ka at millennial or better resolution. The core was split at the National Lacustrine Core Facility (LacCore) in June. The core contains alternating evaporite layers and finely laminated muds which likely indicate times of dryer and wetter conditions. Despite the challenge of alternating lithologies, core recovery and quality are extremely high. Here, we will present our initial chronological and stratigraphic findings. The core record will be dated using a combination of U/Th, 14C and magnetostratigraphy. We will compare our initial stratigraphic description to the existing Searles Lake literature as well as other records from the region, such as data from Devils Hole. These results provide the framework upon which we will develop detailed

Variability of East Asian summer monsoon precipitation during the Holocene and possible forcing mechanisms

Science.gov (United States)

Lu, Fuzhi; Ma, Chunmei; Zhu, Cheng; Lu, Huayu; Zhang, Xiaojian; Huang, Kangyou; Guo, Tianhong; Li, Kaifeng; Li, Lan; Li, Bing; Zhang, Wenqing

2018-03-01

Projecting how the East Asian summer monsoon (EASM) rainfall will change with global warming is essential for human sustainability. Reconstructing Holocene climate can provide critical insight into its forcing and future variability. However, quantitative reconstructions of Holocene summer precipitation are lacking for tropical and subtropical China, which is the core region of the EASM influence. Here we present high-resolution annual and summer rainfall reconstructions covering the whole Holocene based on the pollen record at Xinjie site from the lower Yangtze region. Summer rainfall was less seasonal and 30% higher than modern values at 10-6 cal kyr BP and gradually declined thereafter, which broadly followed the Northern Hemisphere summer insolation. Over the last two millennia, however, the summer rainfall has deviated from the downward trend of summer insolation. We argue that greenhouse gas forcing might have offset summer insolation forcing and contributed to the late Holocene rainfall anomaly, which is supported by the TraCE-21 ka transient simulation. Besides, tropical sea-surface temperatures could modulate summer rainfall by affecting evaporation of seawater. The rainfall pattern concurs with stalagmite and other proxy records from southern China but differs from mid-Holocene rainfall maximum recorded in arid/semiarid northern China. Summer rainfall in northern China was strongly suppressed by high-northern-latitude ice volume forcing during the early Holocene in spite of high summer insolation. In addition, the El Niño/Southern Oscillation might be responsible for droughts of northern China and floods of southern China during the late Holocene. Furthermore, quantitative rainfall reconstructions indicate that the Paleoclimate Modeling Intercomparison Project (PMIP) simulations underestimate the magnitude of Holocene precipitation changes. Our results highlight the spatial and temporal variability of the Holocene EASM precipitation and potential forcing

Cloninger's psychobiological model of personality and psychological distress in fibromyalgia.

Science.gov (United States)

Garcia-Fontanals, Alba; García-Blanco, Susanna; Portell, Mariona; Pujol, Jesús; Poca-Dias, Violant; García-Fructuoso, Ferran; López-Ruiz, Marina; Gutiérrez-Rosado, Teresa; Gomà-I-Freixanet, Montserrat; Deus, Joan

2016-09-01

Personality can play an important role in the clinical symptoms of fibromyalgia (FM). The aim of this study is to identify personality profiles in FM patients and the possible presence of personality disorder (PD) from the Temperament and Character Inventory-Revised (TCI-R), and to assess whether personality dimensions are related to psychological distress in FM. The sample consisted of 42 patients with FM and 38 healthy controls. The TCI-R, Hospital Anxiety and Depression Scale, State-Trait Anxiety Inventory, Short-Form-36 Health Survey, Fibromyalgia Impact Questionnaire and McGill Pain Questionnaire were administered. The personality profile of the FM group based on the TCI-R is defined by high Harm Avoidance (HA), low Novelty Seeking (NS), and low Self-Directedness (SD). Only one-third of patients with FM present a possible psychometric PD, principally from Cluster C. In the FM group, HA and SD are associated positively and negatively, respectively, with indicators of emotional distress. Patients with higher HA present higher perceived pain intensity rated via a verbal-numerical scale while Determination (SD2) reduced the perceived level of pain induced by the stimulus. NS is negatively related to the number of work absences caused by FM. The study suggests that HA and SD play an important role in psychological distress in FM. The fact that SD is prone to modification and has a regulatory effect on emotional impulses is a key aspect to consider from the psychotherapeutic point of view. © 2014 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

Energy policies avoiding a tipping point in the climate system

Energy Technology Data Exchange (ETDEWEB)

Bahn, Olivier [GERAD and Department of Management Sciences, HEC Montreal, Montreal (Qc) (Canada); Edwards, Neil R. [Earth and Environmental Sciences, CEPSAR, Open University, Milton Keynes MK7 6AA (United Kingdom); Knutti, Reto [Institute for Atmospheric and Climate Science, ETH Zurich, CH-8092 Zurich (Switzerland); Stocker, Thomas F. [Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, University of Bern, CH-3012 Bern (Switzerland)

2011-01-15

Paleoclimate evidence and climate models indicate that certain elements of the climate system may exhibit thresholds, with small changes in greenhouse gas emissions resulting in non-linear and potentially irreversible regime shifts with serious consequences for socio-economic systems. Such thresholds or tipping points in the climate system are likely to depend on both the magnitude and rate of change of surface warming. The collapse of the Atlantic thermohaline circulation (THC) is one example of such a threshold. To evaluate mitigation policies that curb greenhouse gas emissions to levels that prevent such a climate threshold being reached, we use the MERGE model of Manne, Mendelsohn and Richels. Depending on assumptions on climate sensitivity and technological progress, our analysis shows that preserving the THC may require a fast and strong greenhouse gas emission reduction from today's level, with transition to nuclear and/or renewable energy, possibly combined with the use of carbon capture and sequestration systems. (author)

The role of forcing and internal dynamics in explaining the ''Medieval Climate Anomaly''

Energy Technology Data Exchange (ETDEWEB)

Goosse, Hugues; Crespin, Elisabeth; Dubinkina, Svetlana; Loutre, Marie-France; Sallaz-Damaz, Yoann [Universite Catholique de Louvain, Earth and Life Institute, Georges Lemaitre Centre for Earth and Climate Research, Louvain-la-Neuve (Belgium); Mann, Michael E. [Pennsylvania State University, Department of Meteorology and Earth and Environmental Systems Institute, University Park, PA (United States); Renssen, Hans [Vrije Universiteit Amsterdam, Section Climate Change and Landscape Dynamics, Department of Earth Sciences, Amsterdam (Netherlands); Shindell, Drew [NASA Goddard Institute for Space Studies, New York City, NY (United States)

2012-12-15

Proxy reconstructions suggest that peak global temperature during the past warm interval known as the Medieval Climate Anomaly (MCA, roughly 950-1250 AD) has been exceeded only during the most recent decades. To better understand the origin of this warm period, we use model simulations constrained by data assimilation establishing the spatial pattern of temperature changes that is most consistent with forcing estimates, model physics and the empirical information contained in paleoclimate proxy records. These numerical experiments demonstrate that the reconstructed spatial temperature pattern of the MCA can be explained by a simple thermodynamical response of the climate system to relatively weak changes in radiative forcing combined with a modification of the atmospheric circulation, displaying some similarities with the positive phase of the so-called Arctic Oscillation, and with northward shifts in the position of the Gulf Stream and Kuroshio currents. The mechanisms underlying the MCA are thus quite different from anthropogenic mechanisms responsible for modern global warming. (orig.)

Non-uniform interhemispheric temperature trends over the past 550 years

Energy Technology Data Exchange (ETDEWEB)

Duncan, Richard P. [Landcare Research, PO Box 40, Lincoln (New Zealand); Lincoln University, Bio-Protection Research Centre, PO Box 84, Lincoln (New Zealand); Fenwick, Pavla; Palmer, Jonathan G. [Gondwana Tree-ring Laboratory, PO Box 14, Canterbury (New Zealand); McGlone, Matt S. [Landcare Research, PO Box 40, Lincoln (New Zealand); Turney, Chris S.M. [University of Exeter, School of Geography, Exeter (United Kingdom)

2010-12-15

The warming trend over the last century in the northern hemisphere (NH) was interrupted by cooling from ad 1940 to 1975, a period during which the southern hemisphere experienced pronounced warming. The cause of these departures from steady warming at multidecadal timescales are unclear; the prevailing explanation is that they are driven by non-uniformity in external forcings but recent models suggest internal climate drivers may play a key role. Paleoclimate datasets can help provide a long-term perspective. Here we use tree-rings to reconstruct New Zealand mean annual temperature over the last 550 years and demonstrate that this has frequently cycled out-of-phase with NH mean annual temperature at a periodicity of around 30-60 years. Hence, observed multidecadal fluctuations around the recent warming trend have precedents in the past, strongly implicating natural climate variation as their cause. We consider the implications of these changes in understanding and modelling future climate change. (orig.)

The Role of Forcing and Internal Dynamics in explaining the 'Medieval Climate Anomaly'

Science.gov (United States)

Goossee, Hugues; Crespin, Elisabeth; Dubinkina, Svetlana; Loutre, Marie-France; Mann, Michael E.; Renssen, Hans; Shindell, Drew

2012-01-01

Proxy reconstructions suggest that peak global temperature during the past warm interval known as the Medieval Climate Anomaly (MCA, roughly 950-1250 AD) has been exceeded only during the most recent decades. To better understand the origin of this warm period, we use model simulations constrained by data assimilation establishing the spatial pattern of temperature changes that is most consistent with forcing estimates, model physics and the empirical information contained in paleoclimate proxy records. These numerical experiments demonstrate that the reconstructed spatial temperature pattern of the MCA can be explained by a simple thermodynamical response of the climate system to relatively weak changes in radiative forcing combined with a modification of the atmospheric circulation, displaying some similarities with the positive phase of the so-called Arctic Oscillation, and with northward shifts in the position of the Gulf Stream and Kuroshio currents. The mechanisms underlying the MCA are thus quite different from anthropogenic mechanisms responsible for modern global warming.

Beyond annual streamflow reconstructions for the Upper Colorado River Basin: a paleo-water-balance approach

Science.gov (United States)

Gangopadhyay, Subhrendu; McCabe, Gregory J.; Woodhouse, Connie A.

2015-01-01

In this paper, we present a methodology to use annual tree-ring chronologies and a monthly water balance model to generate annual reconstructions of water balance variables (e.g., potential evapotrans- piration (PET), actual evapotranspiration (AET), snow water equivalent (SWE), soil moisture storage (SMS), and runoff (R)). The method involves resampling monthly temperature and precipitation from the instrumental record directed by variability indicated by the paleoclimate record. The generated time series of monthly temperature and precipitation are subsequently used as inputs to a monthly water balance model. The methodology is applied to the Upper Colorado River Basin, and results indicate that the methodology reliably simulates water-year runoff, maximum snow water equivalent, and seasonal soil moisture storage for the instrumental period. As a final application, the methodology is used to produce time series of PET, AET, SWE, SMS, and R for the 1404–1905 period for the Upper Colorado River Basin.

Climate variability and climate change

International Nuclear Information System (INIS)

Rind, D.

1990-01-01

Changes of variability with climate change are likely to have a substantial impact on vegetation and society, rivaling the importance of changes in the mean values themselves. A variety of paleoclimate and future climate simulations performed with the GISS global climate model is used to assess how the variabilities of temperature and precipitation are altered as climate warms or cools. In general, as climate warms, temperature variability decreases due to reductions in the latitudinal temperature gradient and precipitation variability increases together with the intensity of the hydrologic cycle. If future climate projections are accurate, the reduction in temperature variability will be minimized by the rapid change in mean temperatures, but the hydrologic variability will be amplified by increased evapotranspiration. Greater hydrologic variability would appear to pose a potentially severe problem for the next century

A regional climate simulation over the Iberian Peninsula for the last millennium

Directory of Open Access Journals (Sweden)

J. J. Gómez-Navarro

2011-04-01

Full Text Available A high-resolution (30 km regional paleoclimate simulation of the last millennium over the Iberian Peninsula (IP is presented. The simulation was performed with a climate version of the mesoscale model MM5 driven by the global model ECHO-G. Both models were driven by the same reconstructions of several external forcing factors. The high spatial resolution of the regional model allows climatologists to realistically simulate many aspects of the climate in the IP, as compared to an observational data set in the reference period 1961–1990. Although the spatial-averaged values developed by the regional model are tightly driven by the boundary conditions, it is capable to develop a different realisation of the past climate at regional scales, especially in the high-frequency domain and for precipitation. This has to be considered when comparing the results of climate simulations versus proxy reconstructions. A preliminary comparison of the simulation results with reconstructions of temperature and precipitation over the IP shows good agreement in the warming trends in the last century of the simulation, although there are large disagreements in key periods such as the precipitation anomalies in the Maunder Minimum.

Chaos, dynamical structure and climate variability

Energy Technology Data Exchange (ETDEWEB)

Stewart, H.B. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science

1995-09-01

Deterministic chaos in dynamical systems offers a new paradigm for understanding irregular fluctuations. Techniques for identifying deterministic chaos from observed data, without recourse to mathematical models, are being developed. Powerful methods exist for reconstructing multidimensional phase space from an observed time series of a single scalar variable; these methods are invaluable when only a single scalar record of the dynamics is available. However, in some applications multiple concurrent time series may be available for consideration as phase space coordinates. Here the authors propose some basic analytical tools for such multichannel time series data, and illustrate them by applications to a simple synthetic model of chaos, to a low-order model of atmospheric circulation, and to two high-resolution paleoclimate proxy data series. The atmospheric circulation model, originally proposed by Lorenz, has 27 principal unknowns; they establish that the chaotic attractor can be embedded in a subspace of eight dimensions by exhibiting a specific subset of eight unknowns which pass multichannel tests for false nearest neighbors. They also show that one of the principal unknowns in the 27-variable model--the global mean sea surface temperature--is of no discernible usefulness in making short-term forecasts.

EFFECTIVENESS OF CHIROPRACTIC ADJUSTMENT IN LUMBAR PAIN IN CROSSFIT PRACTITIONERS

OpenAIRE

MOEHLECKE, DESIREE; FORGIARINI JUNIOR, LUIZ ALBERTO

2017-01-01

ABSTRACT Objective: To evaluate the efficacy of acute chiropractic adjustment in individuals who practice CrossFit with regard to complaints of low back pain and the joint range of motion in this region. Methods: A randomized clinical trial comprised of CrossFit practitioners from a box in Novo Hamburgo-RS, of both sexes and aged 18 to 40 years who had low back pain at the time of the study. The following tools were used: Semi-structured Anamnesis Questionnaire, Visual Analog Scale, McGill ...

Postpartum perineal repair performed by midwives

DEFF Research Database (Denmark)

Kindberg, S; Stehouwer, M; Hvidman, L

2008-01-01

OBJECTIVE: To compare a continuous suture technique with interrupted stitches using inverted knots for postpartum perineal repair of second-degree lacerations and episiotomies. DESIGN: A double-blind randomised controlled trial. SETTING: A Danish university hospital with more than 4800 deliveries...... months postpartum. Pain was evaluated using a visual analogue scale and the McGill Pain Questionnaire. Wound healing was evaluated using the REEDA scale and by assessment of gaping wounds >0.5 cm. Analysis complied with the intention-to-treat principle. MAIN OUTCOME MEASURES: The primary outcome...

Comparison of the RealTime HIV-1, COBAS TaqMan 48 v1.0, Easy Q v1.2, and Versant v3.0 assays for Determination of HIV-1 Viral Loads in a Cohort of Canadian Patients with Diverse HIV Subtype Infections▿

OpenAIRE

Church, Deirdre; Gregson, Daniel; Lloyd, Tracie; Klein, Marina; Beckthold, Brenda; Laupland, Kevin; Gill, M. John

2010-01-01

HIV clinics in Canada provide care to an increasing number of patients born outside of Canada with HIV-1 non-B subtype infections. Because the Easy Q HIV-1 v1.2 assay (EQ; bioMérieux) failed to detect some non-B subtype infections, a multiassay HIV-1 viral load (VL) study was conducted with patients with diverse HIV subtype infections. Patients were enrolled from the Southern Alberta HIV Clinic (SAC), Calgary, Alberta, Canada (n = 349) and the McGill HIV Clinic (MHC), Montreal, Quebec, Canada...

Dolor postoperatorio en mujeres sometidas a cesárea

OpenAIRE

Borges, Natalia Carvalho; Silva, Brunna Costa e; Pedroso, Charlise Fortunato; Silva, Tuany Cavalcante; Tatagiba, Brunna Silva Ferreira; Pereira, Lílian Varanda

2017-01-01

RESUMEN Objetivo Estimar la incidencia, intensidad y calidad del dolor postoperatorio en mujeres sometidas a cesárea. Método Estudio de corte transversal. Fueron entrevistadas 1062 mujeres sometidas a cesárea en el periodo pre y post cirugía inmediatos. La intensidad del dolor y la calidad fueron evaluadas por la Escala Numérica del Dolor (0-10) y el Test de Dolor de McGill. Las variables se analizaron utilizando medidas descriptivas y la incidencia de dolor postoperatorio calculado con u...

Origin of the Squantum 'Tillite', Massachusetts, USA: Modern Analogs and Implications for Neoproterozoic Climate Models

Science.gov (United States)

Carto, S. L.; Eyles, N.

2009-05-01

examination of deposits uncritically labeled as Neoproterozoic 'tillites' by paleoclimate modelers.

Carbonate and lignite cycles in the Ptolemais Basin: Orbital control and suborbital variability (Late Neogene, northern Greece)

Science.gov (United States)

Weber, M. E.; Tougiannidis, N.; Ricken, W.; Rolf, C.; Kleineder, M.; Bertram, N.; Antoniadis, P.

2009-04-01

We recently commenced a project to investigate deep drillings as well as outcrops in the Ptolemais Basin, northern Greece, for paleoenvironmental and paleoclimate change. Specific attention is paid to mining sites Achlada, Vevi, Vegora, Amynteon, North Field, South Field, and Lava. The sediment archive comprises Upper Miocene to Quaternary continental lake deposits (up to 800 m thick) with an extended Lower Pliocene section. The Upper Miocene sections are composed of diatomaceous mud and gray marls. Pliocene lake sediments commence with the Kyrio member (lignite/grey marl), followed by the Theodoxus member (beige marl/lignite), and the Notio member (marl with intercalated sand /lignite). The limnic deposits show striking rhythmic bedding of (mostly) carbonates and lignites, reflecting orbital-induced humidity and temperature changes in this small NW-SE elongated continental basin. First, we retrieved chronometric information by determining magnetic polarity changes on three sites as independent stratigraphic ground-truth in combination with palynological evidence and published data. Then we conducted a number of high-resolution (1 - 6 cm increment), non-destructive measurements to obtain paleoclimate proxies: photospectrometry (colors L, a, b), magnetic susceptibility, and natural gamma. Accordingly, we achieved a multi-proxy insight into paleoclimate and paleoenvironmental evolution at unprecedented temporal resolution (up to a few decades!) over long time series and at a number of key sites. Using the newly-developed ESALab software, we conducted spectral and evolutionary spectral analysis to evaluate the cyclo-stratigraphic development. As for orbital variability, spectral power is concentrated on precession, hemi-precession, and eccentricity, with only minor impact of orbital tilt. We used this information to increase the temporal resolution of our age models by tuning as many precession (insolation) maxima as possible to carbonate minima (lignite maxima

Monte Carlo based electron treatment planning and cutout output factor calculations

Science.gov (United States)

Mitrou, Ellis

Electron radiotherapy (RT) offers a number of advantages over photons. The high surface dose, combined with a rapid dose fall-off beyond the target volume presents a net increase in tumor control probability and decreases the normal tissue complication for superficial tumors. Electron treatments are normally delivered clinically without previously calculated dose distributions due to the complexity of the electron transport involved and greater error in planning accuracy. This research uses Monte Carlo (MC) methods to model clinical electron beams in order to accurately calculate electron beam dose distributions in patients as well as calculate cutout output factors, reducing the need for a clinical measurement. The present work is incorporated into a research MC calculation system: McGill Monte Carlo Treatment Planning (MMCTP) system. Measurements of PDDs, profiles and output factors in addition to 2D GAFCHROMICRTM EBT2 film measurements in heterogeneous phantoms were obtained to commission the electron beam model. The use of MC for electron TP will provide more accurate treatments and yield greater knowledge of the electron dose distribution within the patient. The calculation of output factors could invoke a clinical time saving of up to 1 hour per patient.

Potential links between surging ice sheets, circulation changes and the Dansgaard Oeschger cycles in the Irminger Sea, 60-18 kyr.

NARCIS (Netherlands)

van Krefeld-Alfane, S.; Sarntheim, M.; Erlenkeuser, S.; Grootes, P.; Jung, S.J.A.; Nadeau, M.J.; Pflaumann, U.; Voelker, A.

2000-01-01

Surface and deepwater paleoclimate records in Irminger Sea core SO82-5 (59°N, 31°W) and Icelandic Sea core PS2644 (68°N, 22°W) exhibit large fluctuations in thermohaline circulation (THC) from 60 to 18 calendar kyr B.P., with a dominant periodicity of 1460 years from 46 to 22 calendar kyr B.P.,

Low-Level Laser and Light-Emitting Diode Therapy for Pain Control in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up.

Science.gov (United States)

Lima, Andréa Conceição Gomes; Fernandes, Gilderlene Alves; Gonzaga, Isabel Clarisse; de Barros Araújo, Raimundo; de Oliveira, Rauirys Alencar; Nicolau, Renata Amadei

2016-06-01

This study aimed to evaluate the efficacy of low-level laser therapy (LLLT) and light-emitting diodes (LEDs) for reducing pain in hyperglycemic and normoglycemic patients who underwent coronary artery bypass surgery with internal mammary artery grafts. This study was conducted on 120 volunteers who underwent elective coronary artery bypass graft (CABG) surgery. The volunteers were randomly allocated to four different groups of equal size (n = 30): control, placebo, LLLT [λ = 640 nm and spatial average energy fluence (SAEF) = 1.06 J/cm(2)], and LED (λ = 660 ± 20 nm and SAEF = 0.24 J/cm(2)). Participants were also divided into hyperglycemic and normoglycemic subgroups, according to their fasting blood glucose test result before surgery. The outcome assessed was pain during coughing by a visual analog scale (VAS) and the McGill Pain Questionnaire. The patients were followed for 1 month after the surgery. The LLLT and LED groups showed a greater decrease in pain, with similar results, as indicated by both the VAS and the McGill questionnaire (p ≤ 0.05), on the 6th and 8th postoperative day compared with the placebo and control groups. The outcomes were also similar between hyperglycemic and normoglycemic patients. One month after the surgery, almost no individual reported pain during coughing. LLLT and LED had similar analgesic effects in hyperglycemic and normoglycemic patients, better than placebo and control groups.

An 8700 year paleoclimate reconstruction from the southern Maya lowlands

Science.gov (United States)

Wahl, David B.; Byrne, Roger; Anderson, Lysanna

2014-01-01

Analysis of a sediment core from Lago Puerto Arturo, a closed basin lake in northern Peten, Guatemala, has provided an ∼8700 cal year record of climate change and human activity in the southern Maya lowlands. Stable isotope, magnetic susceptibility, and pollen analyses were used to reconstruct environmental change in the region. Results indicate a relatively wet early to middle Holocene followed by a drier late Holocene, which we interpret as reflecting long-term changes in insolation (precession). Higher frequency variability is more likely attributable to changes in ocean/atmosphere circulation in both the North Atlantic and the Pacific Oceans. Pollen and isotope data show that most of the period of prehispanic agricultural settlement, i.e. ∼5000–1000 cal yr BP, was characterized by drier conditions than previous or subsequent periods. The presence ofZea (corn) pollen through peak aridity during the Terminal Classic period (∼1250–1130 cal yr BP) suggests that drought may not have had as negative an impact as previously proposed. A dramatic negative shift in isotope values indicates an increase in precipitation after ∼950 cal yr BP (hereafter BP).

Age, growth rates, and paleoclimate studies of deep sea corals

Science.gov (United States)

Prouty, Nancy G; Roark, E. Brendan; Andrews, Allen; Robinson, Laura; Hill, Tessa; Sherwood, Owen; Williams, Branwen; Guilderson, Thomas P.; Fallon, Stewart

2015-01-01

Deep-water corals are some of the slowest growing, longest-lived skeletal accreting marine organisms. These habitat-forming species support diverse faunal assemblages that include commercially and ecologically important organisms. Therefore, effective management and conservation strategies for deep-sea corals can be informed by precise and accurate age, growth rate, and lifespan characteristics for proper assessment of vulnerability and recovery from perturbations. This is especially true for the small number of commercially valuable, and potentially endangered, species that are part of the black and precious coral fisheries (Tsounis et al. 2010). In addition to evaluating time scales of recovery from disturbance or exploitation, accurate age and growth estimates are essential for understanding the life history and ecology of these habitat-forming corals. Given that longevity is a key factor for population maintenance and fishery sustainability, partly due to limited and complex genetic flow among coral populations separated by great distances, accurate age structure for these deep-sea coral communities is essential for proper, long-term resource management.

McCall Glacier record of Arctic climate change: Interpreting a northern Alaska ice core with regional water isotopes

Science.gov (United States)

Klein, E. S.; Nolan, M.; McConnell, J.; Sigl, M.; Cherry, J.; Young, J.; Welker, J. M.

2016-01-01

We explored modern precipitation and ice core isotope ratios to better understand both modern and paleo climate in the Arctic. Paleoclimate reconstructions require an understanding of how modern synoptic climate influences proxies used in those reconstructions, such as water isotopes. Therefore we measured periodic precipitation samples at Toolik Lake Field Station (Toolik) in the northern foothills of the Brooks Range in the Alaskan Arctic to determine δ18O and δ2H. We applied this multi-decadal local precipitation δ18O/temperature regression to ∼65 years of McCall Glacier (also in the Brooks Range) ice core isotope measurements and found an increase in reconstructed temperatures over the late-20th and early-21st centuries. We also show that the McCall Glacier δ18O isotope record is negatively correlated with the winter bidecadal North Pacific Index (NPI) climate oscillation. McCall Glacier deuterium excess (d-excess, δ2H - 8*δ18O) values display a bidecadal periodicity coherent with the NPI and suggest shifts from more southwestern Bering Sea moisture sources with less sea ice (lower d-excess values) to more northern Arctic Ocean moisture sources with more sea ice (higher d-excess values). Northern ice covered Arctic Ocean McCall Glacier moisture sources are associated with weak Aleutian Low (AL) circulation patterns and the southern moisture sources with strong AL patterns. Ice core d-excess values significantly decrease over the record, coincident with warmer temperatures and a significant reduction in Alaska sea ice concentration, which suggests that ice free northern ocean waters are increasingly serving as terrestrial precipitation moisture sources; a concept recently proposed by modeling studies and also present in Greenland ice core d-excess values during previous transitions to warm periods. This study also shows the efficacy and importance of using ice cores from Arctic valley glaciers in paleoclimate reconstructions.

Coral based-ENSO/IOD related climate variability in Indonesia: a review

Science.gov (United States)

Yudawati Cahyarini, Sri; Henrizan, Marfasran

2018-02-01

Indonesia is located in the prominent site to study climate variability as it lies between Pacific and Indian Ocean. It has consequences to the regional climate in Indonesia that its climate variability is influenced by the climate events in the Pacific oceans (e.g. ENSO) and in the Indian ocean (e.g. IOD), and monsoon as well as Indonesian Throughflow (ITF). Northwestern monsoon causes rainfall in the region of Indonesia, while reversely Southwestern monsoon causes dry season around Indonesia. The ENSO warm phase called El Nino causes several droughts in Indonesian region, reversely the La Nina causes flooding in some regions in Indonesia. However, the impact of ENSO in Indonesia is different from one place to the others. Having better understanding on the climate phenomenon and its impact to the region requires long time series climate data. Paleoclimate study which provides climate data back into hundreds to thousands even to million years overcome this requirement. Coral Sr/Ca can provide information on past sea surface temperature (SST) and paired Sr/Ca and δ18O may be used to reconstruct variations in the precipitation balance (salinity) at monthly to annual interannual resolution. Several climate studies based on coral geochemical records in Indonesia show that coral Sr/Ca and δ18O from Indonesian records SST and salinity respectively. Coral Sr/Ca from inshore Seribu islands complex shows more air temperature rather than SST. Modern coral from Timor shows the impact of ENSO and IOD to the saliniy and SST is different at Timor sea. This result should be taken into account when interpreting Paleoclimate records over Indonesia. Timor coral also shows more pronounced low frequency SST variability compared to the SST reanalysis (model). The longer data of low frequency variability will improve the understanding of warming trend in this climatically important region.

Biological forcing controls the chemistry of the coral exoskeleton

Science.gov (United States)

Meibom, A.; Mostefaoui, S.; Cuif, J.; Yurimoto, H.; Dauphin, Y.; Houlbreque, F.; Dunbar, R.; Constantz, B.

2006-12-01

A multitude of marine organisms produce calcium carbonate skeletons that are used extensively to reconstruct water temperature variability of the tropical and subtropical oceans - a key parameter in global climate-change models. Such paleo-climate reconstructions are based on the notion that skeletal oxygen isotopic composition and certain trace-element abundances (e.g., Sr/Ca and Mg/Ca ratios) vary in response to changes in the water temperature. However, it is a fundamental problem that poorly understood biological processes introduce large compositional deviations from thermodynamic equilibrium and hinder precise calibrations of many paleo-climate proxies. Indeed, the role of water temperature in controlling the composition of the skeleton is far from understood. We have studied trace-element abundances as well as oxygen and carbon isotopic compositions of individual skeletal components in the zooxanthellate and non-zooxanthellate corals at ultra-structural, i.e. micrometer to sub-micrometer length scales. From this body of work we draw the following, generalized conclusions: 1) Centers of calcification (COC) are not in equilibrium with seawater. Notably, the Sr/Ca ratio is higher than expected for aragonite equilibrium with seawater at the temperature at which the skeleton was formed. Furthermore, the COC are further away from equilibrium with seawater than fibrous skeleton in terms of stable isotope composition. 2) COC are dramatically different from the fibrous aragonite skeleton in terms of trace element composition. 3) Neither trace element nor stable isotope variations in the fibrous (bulk) part of the skeleton are directly related to changes in SST. In fact, changes in SST can have very little to do with the observed compositional variations. 4) Trace element variations in the fibrous (bulk) part of the skeleton are not related to the activity of zooxanthellae. These observations are directly relevant to the issue of biological versus non

Growth ring analysis of fossil coniferous woods from early cretaceous of Araripe Basin (Brazil

Directory of Open Access Journals (Sweden)

Etiene F. Pires

2011-06-01

Full Text Available Growth ring analysis on silicified coniferous woods from the Missão Velha Formation (Araripe Basin - Brazil has yielded important information about periodicity of wood production during the Early Cretaceous in the equatorial belt. Despite warm temperatures, dendrological data indicate that the climate was characterized by cyclical alternation of dry and rainy periods influenced by cyclical precipitations, typical of tropical wet and dry or savanna climate. The abundance of false growth rings can be attributed to both occasional droughts and arthropod damage. The present climate data agree with palaeoclimatic models that inferred summer-wet biomes for the Late Jurassic/Early Cretaceous boundary in the southern equatorial belt.A partir de análise de anéis de crescimento em lenhos de coníferas silicificadas provenientes da Formação Missão Velha(Bacia do Araripe - Brasil, obteve-se importantes informações a respeito da periodicidade de produção lenhosa duranteo início do Cretáceo, na região do equador. Apesar das estimativas de temperatura apresentarem-se elevadas, os dados dendrológicos indicam que o clima foi caracterizado pela alternância cíclica de períodos secos e chuvosos, influenciado por precipitações periódicas, típico das condições atuais de climatropical úmido e seco ou savana. A abundância de falsosanéis de crescimento pode ser atribuída tanto a secas ocasionais quanto a danos causados por artrópodes. Os dados paleoclimáticos aqui obtidos corroboram com modelos paleoclimáticos que inferem a ocorrência de um bioma de verões úmidos para o limite Neojurássico/Eocretáceo ao sul do equador.

A pseudoproxy assessment of data assimilation for reconstructing the atmosphere-ocean dynamics of hydroclimate extremes

Science.gov (United States)

Steiger, Nathan J.; Smerdon, Jason E.

2017-10-01

Because of the relatively brief observational record, the climate dynamics that drive multiyear to centennial hydroclimate variability are not adequately characterized and understood. Paleoclimate reconstructions based on data assimilation (DA) optimally fuse paleoclimate proxies with the dynamical constraints of climate models, thus providing a coherent dynamical picture of the past. DA is therefore an important new tool for elucidating the mechanisms of hydroclimate variability over the last several millennia. But DA has so far remained untested for global hydroclimate reconstructions. Here we explore whether or not DA can be used to skillfully reconstruct global hydroclimate variability along with the driving climate dynamics. Through a set of idealized pseudoproxy experiments, we find that an established DA reconstruction approach can in principle be used to reconstruct hydroclimate at both annual and seasonal timescales. We find that the skill of such reconstructions is generally highest near the proxy sites. This set of reconstruction experiments is specifically designed to estimate a realistic upper bound for the skill of this DA approach. Importantly, this experimental framework allows us to see where and for what variables the reconstruction approach may never achieve high skill. In particular for tree rings, we find that hydroclimate reconstructions depend critically on moisture-sensitive trees, while temperature reconstructions depend critically on temperature-sensitive trees. Real-world DA-based reconstructions will therefore likely require a spatial mixture of temperature- and moisture-sensitive trees to reconstruct both temperature and hydroclimate variables. Additionally, we illustrate how DA can be used to elucidate the dynamical mechanisms of drought with two examples: tropical drivers of multiyear droughts in the North American Southwest and in equatorial East Africa. This work thus provides a foundation for future DA-based hydroclimate

Wood anatomy reveals high theoretical hydraulic conductivity and low resistance to vessel implosion in a Cretaceous fossil forest from northern Mexico.

Science.gov (United States)

Martínez-Cabrera, Hugo I; Estrada-Ruiz, Emilio

2014-01-01

The Olmos Formation (upper Campanian), with over 60 angiosperm leaf morphotypes, is Mexico's richest Cretaceous flora. Paleoclimate leaf physiognomy estimates indicate that the Olmos paleoforest grew under wet and warm conditions, similar to those present in modern tropical rainforests. Leaf surface area, tree size and climate reconstructions suggest that this was a highly productive system. Efficient carbon fixation requires hydraulic efficiency to meet the evaporative demands of the photosynthetic surface, but it comes at the expense of increased risk of drought-induced cavitation. Here we tested the hypothesis that the Olmos paleoforest had high hydraulic efficiency, but was prone to cavitation. We characterized the hydraulic properties of the Olmos paleoforest using theoretical conductivity (Ks), vessel composition (S) and vessel fraction (F), and measured drought resistance using vessel implosion resistance (t/b)h(2) and the water potential at which there is 50% loss of hydraulic conductivity (P50). We found that the Olmos paleoforest had high hydraulic efficiency, similar to that present in several extant tropical-wet or semi-deciduous forest communities. Remarkably, the fossil flora had the lowest (t/b)h(2), which, together with low median P50 (-1.9 MPa), indicate that the Olmos paleoforest species were extremely vulnerable to drought-induced cavitation. Our findings support paleoclimate inferences from leaf physiognomy and paleoclimatic models suggesting it represented a highly productive wet tropical rainforest. Our results also indicate that the Olmos Formation plants had a large range of water conduction strategies, but more restricted variation in cavitation resistance. These straightforward methods for measuring hydraulic properties, used herein for the first time, can provide useful information on the ecological strategies of paleofloras and on temporal shifts in ecological function of fossil forests chronosequences.

Water and carbon stable isotope records from natural archives: a new database and interactive online platform for data browsing, visualizing and downloading

Science.gov (United States)

Bolliet, Timothé; Brockmann, Patrick; Masson-Delmotte, Valérie; Bassinot, Franck; Daux, Valérie; Genty, Dominique; Landais, Amaelle; Lavrieux, Marlène; Michel, Elisabeth; Ortega, Pablo; Risi, Camille; Roche, Didier M.; Vimeux, Françoise; Waelbroeck, Claire

2016-08-01

paleoclimate community. For coherency with the Paleoclimate Modelling Intercomparison Project (PMIP), we focus on records spanning the past 200 years, the mid-Holocene (MH, 5.5-6.5 ka; calendar kiloyears before 1950), the Last Glacial Maximum (LGM, 19-23 ka), and those spanning the last interglacial period (LIG, 115-130 ka). Basic statistics have been applied to characterize anomalies between these different periods. Most changes from the MH to present day and from LIG to MH appear statistically insignificant. Significant global differences are reported from LGM to MH with regional discrepancies in signals from different archives and complex patterns.

Net greenhouse gas emissions at Eastmain-1 reservoir, Quebec, Canada

Energy Technology Data Exchange (ETDEWEB)

Tremblay, Alain; Bastien, Julie; Bonneville, Marie-Claude; del Giorgio, Paul; Demarty, Maud; Garneau, Michelle; Helie, Jean-Francois; Pelletier, Luc; Prairie, Yves; Roulet, Nigel; Strachan, Ian; Teodoru, Cristian

2010-09-15

The growing concern regarding the long-term contribution of freshwater reservoirs to atmospheric greenhouse gases (GHG), led Hydro-Quebec, to study net GHG emissions from Eastmain 1 reservoir, which are the emissions related to the creation of a reservoir minus those that would have been emitted or absorbed by the natural systems over a 100-year period. This large study was realized in collaboration with University du Quebec a Montreal, McGill University and Environnement IIlimite Inc. This is a world premiere and the net GHG emissions of EM-1 will be presented in details.

Stereotactic Fractionated Radiotherapy in the Treatment of Juxtapapillary Choroidal Melanoma: The McGill University Experience

International Nuclear Information System (INIS)

Al-Wassia, Rolina; Dal Pra, Alan; Shun, Kitty; Shaban, Ahmed; Corriveau, Christine; Edelstein, Chaim; Deschenes, Jean; Ruo, Russel; Patrocinio, Horacio; Cury, Fabio L.B.; DeBlois, François; Shenouda, George

2011-01-01

Purpose: To report our experience with linear accelerator-based stereotactic fractionated radiotherapy in the treatment of juxtapapillary choroidal melanoma. Methods and Materials: We performed a retrospective review of 50 consecutive patients diagnosed with juxtapapillary choroidal melanoma and treated with linear accelerator-based stereotactic fractionated radiotherapy between April 2003 and December 2009. Patients with small to medium sized lesions (Collaborative Ocular Melanoma Study classification) located within 2 mm of the optic disc were included. The prescribed radiation dose was 60 Gy in 10 fractions. The primary endpoints included local control, enucleation-free survival, and complication rates. Results: The median follow-up was 29 months (range, 1–77 months). There were 31 males and 29 females, with a median age of 69 years (range, 30–92 years). Eighty-four percent of the patients had medium sized lesions, and 16% of patients had small sized lesions. There were four cases of local progression (8%) and three enucleations (6%). Actuarial local control rates at 2 and 5 years were 93% and 86%, respectively. Actuarial enucleation-free survival rates at 2 and 5 years were 94% and 84%, respectively. Actuarial complication rates at 2 and 5 years were 33% and 88%, respectively, for radiation-induced retinopathy; 9.3% and 46.9%, respectively, for dry eye; 12% and 53%, respectively, for cataract; 30% and 90%, respectively, for visual loss [Snellen acuity (decimal equivalent), <0.1]; 11% and 54%, respectively, for optic neuropathy; and 18% and 38%, respectively, for neovascular glaucoma. Conclusions: Linear accelerator-based stereotactic fractionated radiotherapy using 60 Gy in 10 fractions is safe and has an acceptable toxicity profile. It has been shown to be an effective noninvasive treatment for juxtapapillary choroidal melanomas.

Stereotactic Fractionated Radiotherapy in the Treatment of Juxtapapillary Choroidal Melanoma: The McGill University Experience

Energy Technology Data Exchange (ETDEWEB)

Al-Wassia, Rolina; Dal Pra, Alan; Shun, Kitty; Shaban, Ahmed [Department of Oncology, Division of Radiation Oncology, Montreal General Hospital, McGill University Health Centre, Montreal, Quebec (Canada); Corriveau, Christine [Department of Ophthalmology, Notre Dame Hospital, Centre Hospitalier de l' Universite de Montreal, Montreal, Quebec (Canada); Edelstein, Chaim; Deschenes, Jean [Department of Ophthalmology, McGill University Health Centre, Montreal, Quebec (Canada); Ruo, Russel; Patrocinio, Horacio [Department of Medical Physics, Montreal General Hospital, McGill University Health Centre, Montreal, Quebec (Canada); Cury, Fabio L.B. [Department of Oncology, Division of Radiation Oncology, Montreal General Hospital, McGill University Health Centre, Montreal, Quebec (Canada); DeBlois, Francois [Department of Medical Physics, Jewish General Hospital, McGill University, Montreal, Quebec (Canada); Shenouda, George, E-mail: george.shenouda@muhc.mcgill.ca [Department of Oncology, Division of Radiation Oncology, Montreal General Hospital, McGill University Health Centre, Montreal, Quebec (Canada)

2011-11-15

Purpose: To report our experience with linear accelerator-based stereotactic fractionated radiotherapy in the treatment of juxtapapillary choroidal melanoma. Methods and Materials: We performed a retrospective review of 50 consecutive patients diagnosed with juxtapapillary choroidal melanoma and treated with linear accelerator-based stereotactic fractionated radiotherapy between April 2003 and December 2009. Patients with small to medium sized lesions (Collaborative Ocular Melanoma Study classification) located within 2 mm of the optic disc were included. The prescribed radiation dose was 60 Gy in 10 fractions. The primary endpoints included local control, enucleation-free survival, and complication rates. Results: The median follow-up was 29 months (range, 1-77 months). There were 31 males and 29 females, with a median age of 69 years (range, 30-92 years). Eighty-four percent of the patients had medium sized lesions, and 16% of patients had small sized lesions. There were four cases of local progression (8%) and three enucleations (6%). Actuarial local control rates at 2 and 5 years were 93% and 86%, respectively. Actuarial enucleation-free survival rates at 2 and 5 years were 94% and 84%, respectively. Actuarial complication rates at 2 and 5 years were 33% and 88%, respectively, for radiation-induced retinopathy; 9.3% and 46.9%, respectively, for dry eye; 12% and 53%, respectively, for cataract; 30% and 90%, respectively, for visual loss [Snellen acuity (decimal equivalent), <0.1]; 11% and 54%, respectively, for optic neuropathy; and 18% and 38%, respectively, for neovascular glaucoma. Conclusions: Linear accelerator-based stereotactic fractionated radiotherapy using 60 Gy in 10 fractions is safe and has an acceptable toxicity profile. It has been shown to be an effective noninvasive treatment for juxtapapillary choroidal melanomas.