2,871 research outputs found
Divergence in seasonal hydrology across northern Eurasia: Emerging trends and water cycle linkages
Discharge from large Eurasia rivers increased during the 20th century, yet much remains unknown regarding details of this increasing freshwater flux. Here, for the three largest Eurasian basins (the Ob, Yenisei, and Lena) we examine the nature of annual and seasonal discharge trends by investigating the flow changes along with those for precipitation, snow depth, and snow water equivalent. On the basis of a multiperiod trend analysis and examination of station data, we propose two characteristic regimes to explain the longâterm discharge increase from these large Eurasian rivers. Over the early decades from approximately 1936 to 1965, annual precipitation correlates well with annual discharge, and positive discharge trends are concurrent with summer/fall discharge increases. The latter decades were marked by a divergence between winter/spring flows, which increased, amid summer/fall discharge declines. A comparison of cold season precipitation (CSP) and spring discharge trends across subbasins of the Ob, Yenisei, and Lena shows limited agreement with one precipitation data set but good agreement (R2 \u3e 0.90) when a second is used. While natural variability in the Arctic system tends to mask these emerging trends, spatial and temporal changes can generally be characterized by increased solid precipitation, primarily to the north, along with a drier hydrography during the warm season
Impact of Unexpected Events, Shocking News and Rumours on Foreign Exchange Market Dynamics
We analyze the dynamical response of the world's financial community to
various types of unexpected events, including the 9/11 terrorist attacks as
they unfolded on a minute-by-minute basis. We find that there are various
'species' of news, characterized by how quickly the news get absorbed, how much
meaning and importance is assigned to it by the community, and what subsequent
actions are then taken. For example, the response to the unfolding events of
9/11 shows a gradual collective understanding of what was happening, rather
than an immediate realization. For news items which are not simple economic
statements, and hence whose implications are not immediately obvious, we
uncover periods of collective discovery during which collective opinions seem
to oscillate in a remarkably synchronized way. In the case of a rumour, our
findings also provide a concrete example of contagion in inter-connected
communities. Practical applications of this work include the possibility of
producing selective newsfeeds for specific communities, based on their likely
impact
Threeâdimensional forward stratigraphic modelling of the sedimentary architecture of meanderingâriver successions in evolving halfâgraben rift basins
The spatial organisation of meanderingâriver deposits varies greatly within the sedimentary fills of rift basins, depending on how differential rates of fault propagation and subsidence interplay with autogenic processes to drive changes in fluvial channelâbelt position and rate of migration, avulsion frequency and mechanisms of meanderâbend cut off. This set of processes fundamentally influences stacking patterns of the accumulated successions. Quantitative predictions of the spatioâtemporal evolution and internal architecture of meandering fluvial deposits in such tectonically active settings remain limited. A numerical forward stratigraphic modelâthe PointâBar Sedimentary Architecture Numerical Deduction (PBâSAND)âis applied to examine relationships between differential rates of subsidence and resultant fluvial channelâbelt migration, reach avulsion and channelâdeposit stacking in active, faultâbounded halfâgrabens. The model is used to reconstruct and predict the complex morphodynamics of fluvial meanders, their generated channel belts, and the associated lithofacies distributions that accumulate as heterogeneous fluvial successions in rift settings, constrained by data from seismic images and outcrop successions. The 3D modelling outputs are used to explore sedimentary heterogeneity at various spatioâtemporal scales. Results show how the connectivity of sandâprone geobodies can be quantified as a function of subsidence rate, which itself decreases both along and away from the basinâbounding fault. In particular, results highlight the spatial variability in the size and connectedness of sandâprone geobodies that is seen in directions perpendicular and parallel to the basin axis, and that arises as a function of the interaction between spatial and temporal variations in rates of accommodation generation and faultâinfluenced changes in river morphodynamics. The results have applied significance, for example, to both hydrocarbon exploration and assessment of groundwater aquifers. The expected greatest connectivity of fluvial sandbody in a halfâgraben is primarily determined by the complex interplay between the frequency and rate of subsidence, the style of basin propagation, the rates of migration of channel belts, the frequency of avulsion and the proportion and spatial distribution of variably sandâprone channel and bar deposits
Plasticity Through Canalization: The Contrasting Effect of Temperature on Trait Size and Growth in Drosophila
In most ectotherms, a reduction in developmental temperature leads to an increase in body size, a phenomenon known as the temperature size rule (TSR). In Drosophila melanogaster, temperature affects body size primarily by affecting critical size, the point in development when larvae initiate the hormonal cascade that stops growth and starts metamorphosis. However, while the thermal plasticity of critical size can explain the effect of temperature on overall body size, it cannot entirely account for the effect of temperature on the size of individual traits, which vary in their thermal sensitivity. Specifically, the legs and male genitalia show reduced thermal plasticity for size, while the wings show elevated thermal plasticity, relative to overall body size. Here, we show that these differences in thermal plasticity among traits reflect, in part, differences in the effect of temperature on the rates of cell proliferation during trait growth. Counterintuitively, the elevated thermal plasticity of the wings is due to canalization in the rate of cell proliferation across temperatures. The opposite is true for the legs. These data reveal that environmental canalization at one level of organization may explain plasticity at another, and vice versa
Structural and metabolic correlates of neuropsychological profiles in multiple system atrophy and Parkinson's disease
Functional neuroanatomical correlates of episodic memory impairment in early phase psychosis
Studies have demonstrated that episodic memory (EM) is often preferentially disrupted in schizophrenia. The neural substrates that mediate EM impairment in this illness are not fully understood. Several functional magnetic resonance imaging (fMRI) studies have employed EM probe tasks to elucidate the neural underpinnings of impairment, though results have been inconsistent. The majority of EM imaging studies have been conducted in chronic forms of schizophrenia with relatively few studies in early phase patients. Early phase schizophrenia studies are important because they may provide information regarding when EM deficits occur and address potential confounds more frequently observed in chronic populations. In this study, we assessed brain activation during the performance of visual scene encoding and recognition fMRI tasks in patients with earlyphase psychosis (n = 35) and age, sex, and race matched healthy control subjects (n = 20). Patients demonstrated significantly lower activation than controls in the right hippocampus and left fusiform gyrus during scene encoding and lower activation in the posterior cingulate, precuneus, and left middle temporal cortex during recognition of target scenes. Symptom levels were not related to the imaging findings, though better cognitive performance in patients was associated with greater right hippocampal activation during encoding. These results provide evidence of altered function in neuroanatomical circuitry subserving EM early in the course of psychotic illness, which may have implications for pathophysiological models of this illness
Innate and adaptive humoral responses coat distinct commensal bacteria with immunoglobulin A
Immunoglobulin A (IgA) is prominently secreted at mucosal surfaces and coats a fraction of the intestinal microbiota. However, the commensal bacteria bound by IgA are poorly characterized and the type of humoral immunity they elicit remains elusive. We used bacterial flow cytometry coupled with 16S rRNA gene sequencing (IgA-Seq) in murine models of immunodeficiency to identify IgA-bound bacteria and elucidate mechanisms of commensal IgA targeting. We found that residence in the small intestine, rather than bacterial identity, dictated induction of specific IgA. Most commensals elicited strong T-independent (TI) responses that originated from the orphan B1b lineage and from B2 cells, but excluded natural antibacterial B1a specificities. Atypical commensals including segmented filamentous bacteria and Mucispirillum evaded TI responses but elicited T-dependent IgA. These data demonstrate exquisite targeting of distinct commensal bacteria by multiple layers of humoral immunity and reveal a specialized function of the B1b lineage in TI mucosal IgA responses
Amine Dynamics in Diamine-Appended Mg2(dobpdc) Metal-Organic Frameworks.
Variable-temperature 15N solid-state NMR spectroscopy is used to uncover the dynamics of three diamines appended to the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate), an important family of CO2 capture materials. The results imply both bound and free amine nitrogen environments exist when diamines are coordinated to the framework open Mg2+ sites. There are rapid exchanges between two nitrogen environments for all three diamines, the rates and energetics of which are quantified by 15N solid-state NMR data and corroborated by density functional theory calculations and molecular dynamics simulations. The activation energy for the exchange provides a measure of the metal-amine bond strength. The unexpected negative correlation between the metal-amine bond strength and CO2 adsorption step pressure reveals that metal-amine bond strength is not the only important factor in determining the CO2 adsorption properties of diamine-appended Mg2(dobpdc) metal-organic frameworks
THE EDINBURGH RANDOMIZED TRIAL OF BREAST-CANCER SCREENING - RESULTS AFTER 10 YEARS OF FOLLOW-UP
The Edinburgh Randomised Trial of Breast Cancer Screening recruited 44,288 women aged 45-64 years into the initial cohort of the trial during 1978-81, and 10 years of follow-up is now complete. A total of 22,944 women were randomised into the study group and were offered screening for 7 years; the remaining women formed the control group. After 10 years, breast cancer mortality is 14-21% lower in the study group than in the controls depending on the precise definition of the end point. These differences are not statistically significant; for breast cancer as the underlying cause of death the relative risk is 0.82 (95% confidence interval 0.61-1.11). Rates of locally advanced and metastatic cancer were substantially lower in the study group, but screening has failed to achieve marked reductions in rates of small node-positive cancers. Those women who accepted the final invitation to screening have been monitored over the 3 year period prior to their first screen under the UK service screening programme. Interval cases, expressed as a proportion of the control incidence, increased from 12% in the first year to 67% in the third year. The reduction in breast cancer mortality for older women (aged at least 50 years) is the same as that for the total study group for this duration of follow-up. For analyses of breast cancer mortality in younger women updates recruited to the trial from 1982 to 1985 (10,383 women with 6-8 years' follow-up) have been included. The reduction in breast cancer mortality for women aged 45-49 years at entry was 22% (relative risk = 0.78, 95% confidence interval = 0.46-1.31)
'Memory Must Be Defended': Beyond the Politics of Mnemonical Security
This article supplements and extends the ontological security theory in International Relations (IR) by conceptualizing the notion of mnemonical security. It engages critically the securitization of memory as a means of making certain historical remembrances secure by delegitimizing or outright criminalizing others. The securitization of historical memory by means of law tends to reproduce a sense of insecurity among the contesters of the âmemoryâ in question. To move beyond the politics of mnemonical security, two lines of action are outlined: (i) the âdesecuritizationâ of social remembrance in order to allow for its repoliticization, and (ii) the rethinking of the selfâother relations in mnemonic conflicts. A radically democratic, agonistic politics of memory is called for that would avoid the knee-jerk reactive treatment of identity, memory and history as problems of security. Rather than trying to secure the unsecurable, a genuinely agonistic mnemonic pluralism would enable different interpretations of the past to be questioned, in place of pre-defining national or regional positions on legitimate remembrance in ontological security terms
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