1,154 research outputs found
Parsimonious Catchment and River Flow Modelling
It is increasingly the case that models are being developed as âevolvingâ products rather than\ud
one-off application tools, such that auditable modelling versus ad hoc treatment of models becomes a\ud
pivotal issue. Auditable modelling is particularly vital to âparsimonious modellingâ aimed at meeting\ud
specific modelling requirements. This paper outlines various contributory factors and aims to seed\ud
proactively a research topic by inextricably linking value/risk management to parsimonious modelling.\ud
Value management in modelling may be implemented in terms of incorporating âenough detailâ into a\ud
model so that the synergy among the constituent units of the model captures that of the real system. It is a\ud
problem of diminishing returns, since further reductions in the constituent units will create an\ud
unacceptable difference between the model and the real system; conversely, any further detail will add to\ud
the cost of modelling without returning any significant benefit. The paper also defines risk management\ud
in relation to modelling. It presents a qualitative framework for value/risk management towards\ud
parsimonious modelling by the categorisation of âmodelling techniquesâ in terms of âcontrol volume.
Molecular imaging of depressive disorders
This chapter summarizes findings of a large number of molecular imaging studies in the field of unipolar and bipolar depression (BD). Brain metabolism in depressed unipolar and bipolar patients is generally hypoactive in the middle frontal gyri, the pregenual and posterior anterior cingulate, the superior temporal gyrus, the insula, and the cerebellum, while hyperactivity exists in subcortical (caudate nucleus, thalamus), limbic (amygdala, anterior hippocampus), and medial and inferior frontal regions. Interestingly, after depletion of serotonin or noradrenalin/dopamine in vulnerable (recovered) major depressive disorder (MDD) patients, a similar response pattern in metabolism occurs. Findings on the pre-and postsynaptic dopaminergic system show indications that, at least in subgroups of retarded MDD patients, presynaptic dopaminergic markers may be decreased, while postsynaptic markers may be increased. The findings regarding serotonin synthesis, pre-and postsynaptic imaging can be integrated to a presumable loss of serotonin in MDD, while this remains unclear in BD. This reduction of serotonin and dopamine in MDD was recently summarized in a revised version of the monoamine hypothesis, which focuses more on a dysfunction at the level of the MAO enzyme. This should be addressed further in future studies. Nevertheless, it should be acknowledged that the serotonergic and dopaminergic systems appear adaptive; therefore, it remains difficult to distinguish state and trait abnormalities. Therefore, future longitudinal molecular imaging studies in the same subjects at different clinical mood states (preferably with different tracers and imaging modalities) are needed to clarify whether the observed changes in transporters and receptors are compensatory reactions or reflect different, potentially causal mechanisms. Several suggestions for future developments are also provided at the end of this chapter.</p
Passive sampling and benchmarking to rank HOC levels in the aquatic environment
The identification and prioritisation of water bodies presenting elevated levels of anthropogenic chemicals is a key aspect of environmental monitoring programmes. Albeit this is challenging owing to geographical scales, choice of indicator aquatic species used for chemical monitoring, and inherent need for an understanding of contaminant fate and distribution in the environment. Here, we propose an innovative methodology for identifying and ranking water bodies according to their levels of hydrophobic organic contaminants (HOCs) in water. This is based on a unique passive sampling dataset acquired over a 10-year period with silicone rubber exposures in surface water bodies across Europe. We show with these data that, far from point sources of contamination, levels of hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) in water approach equilibrium with atmospheric concentrations near the air/water surface. This results in a relatively constant ratio of their concentrations in the water phase. This, in turn, allows us to (i) identify sites of contamination with either of the two chemicals when the HCB/PeCB ratio deviates from theory and (ii) define benchmark levels of other HOCs in surface water against those of HCB and/or PeCB. For two polychlorinated biphenyls (congener 28 and 52) used as model chemicals, differences in contamination levels between the more contaminated and pristine sites are wider than differences in HCB and PeCB concentrations endorsing the benchmarking procedure
Molecular imaging of depressive disorders
This chapter summarizes findings of a large number of molecular imaging studies in the field of unipolar and bipolar depression (BD). Brain metabolism in depressed unipolar and bipolar patients is generally hypoactive in the middle frontal gyri, the pregenual and posterior anterior cingulate, the superior temporal gyrus, insula, and the cerebellum, while hyperactivity exists in subcortical (caudate nucleus, thalamus), limbic (amygdala, anterior hippocampus), and medial and inferior frontal regions. Interestingly, after depletion of serotonin or noradrenalin/dopamine in vulnerable (recovered) major depressive disorder (MDD) patients, a similar response pattern in metabolism occurs. Findings on the pre- and postsynaptic dopaminergic system show indications that, at least in subgroups of retarded MDD patients, presynaptic dopaminergic markers may be decreased, while postsynaptic markers may be increased. The findings regarding serotonin synthesis, pre- and postsynaptic imaging can be integrated to a presumable loss of serotonin in MDD, while this remains unclear in BD. This reduction of serotonin and dopamine in MDD was recently summarized in a revised version of the monoamine hypothesis, which focuses more on a dysfunction at the level of the MAO enzyme. This should be addressed further in future studies. Furthermore, future longitudinal molecular imaging studies in the same subjects at different clinical mood states are needed to clarify whether the observed changes in transporters and receptors are compensatory reactions or reflect different, potentially causal mechanisms. Several suggestions for future developments are also provided.</p
Novel Josephson Junction Geometries in NbCu bilayers fabricated by Focused Ion Beam Microscope
We explore novel junction configurations as an extension of our established
Focused Ion Beam-based low TC SNS Junction fabrication technique. By milling a
circular trench (diameter 1 micron, width 50 nm) in a 125 nm Nb 75 nm Cu
bilayer we define a superconducting island connected to the bulk of the film by
a normal metal barrier and entirely enclosed in-plane by the superconducting
film. The circular junction properties can be probed by depositing an
insulating layer over the device and drilling a 0.3 micron diameter hole down
to the island to allow a Nb via to be deposited. Device behavior has been
studied at 4.2 K. An SNS-like current voltage characteristic and Shapiro steps
are observed. It is in terms of magnetic field behavior that the device
exhibits novel characteristics: as the device is entirely enclosed in type II
superconductor, when a magnetic field is applied perpendicular to the plane of
the film, only quantized flux can enter the junction. Hence as applied magnetic
field is increased the junction critical current is unchanged, then abruptly
suppressed as soon as a flux quantum enters (close to the expected value of
lower critical field for the film).Comment: 10 pages including 6 figures Minor Corrections inlight of referees'
comment
Transdiagnostic factors predicting the 2-year disability outcome in patients with anxiety and depressive disorders
Background: Both anxiety and depressive disorders are associated with significant long-term disability. Since experienced impairments vary between patients independent of diagnosis and disease severity, identifying transdiagnostic factors that predict the course of disability may provide new targets to reduce disability. This study examines transdiagnostic factors predicting the 2-year disability outcome in patients with anxiety and/or depressive disorders (ADD), focusing on potentially malleable factors.Methods: Six hundred fifteen participants with a current diagnosis of ADD from the Netherlands Study of Depression and Anxiety (NESDA) were included. Disability was assessed at baseline and after 2Â years of follow-up, using the 32-item WHODAS II questionnaire. Transdiagnostic predictors of 2-year disability outcome were identified using linear regression analysis.Results: In univariable analyses, transdiagnostic factors associated with the 2-year disability outcome were locus of control (standardized ÎČ = -0.116, p = 0.011), extraversion (standardized ÎČ = -0.123 p = 0.004) and experiential avoidance (standardized ÎČ = 0.139, p = 0.001). In multivariable analysis, extraversion had a unique predictive value (standardized ÎČ = -0.143 p = 0.003). A combination of sociodemographic, clinical and transdiagnostic variables resulted in an explained variance (R2) of 0.090). The explained variance of a combination of transdiagnostic factors was 0.050.Conclusion: The studied transdiagnostic variables explain a small but unique part of variability in the 2-year disability outcome. Extraversion is the only malleable transdiagnostic factor predictive of the course of disability independent of other variables. Due to the small contribution to the variance in the disability outcome, the clinical relevance of targeting extraversion seems limited. However, its predictive value is comparable to that of accepted disease severity measures, supporting the importance of looking beyond using disease severity measures as predictors. Furthermore, studies including extraversion in combination with other transdiagnostic and environmental factors may elucidate the unexplained part of variability of the course of disability in patients with ADD.</p
Climatic variability and periodicity for upstream sub-basins of the Yangtze river, China
The headwaters of the Yangtze River are located on the Qinghai Tibetan Plateau, which is affected by climate change. Here, treamflow trends for Tuotuohe and Zhimenda sub-basins and relations to temperature and precipitation trends during 1961â2015 were investigated. The modified MannâKendall trend test, Pettitt test, wavelet analysis, and multivariate correlation analysis was deployed for this purpose. The temperature and precipitation significantly increased for each sub-basin, and the temperature increase was more significant in Tuotuohe sub-basin as compared to the Zhimenda sub-basin. A statistically significant periodicity of 2â4 years was observed for both sub-basins in different time spans. Higher flow periodicities for Tuotuohe and Zhimenda sub-basin were found after 1991 and 2004, respectively, which indicates that these are the change years of trends in streamflows. The influence of temperature on streamflow is more substantial in Tuotuohe sub-basin, which will ultimately impact the melting of glaciers and snowmelt runoff in this sub-basin. Precipitation plays a more critical role in the Zhimenda streamflow. Precipitation and temperature changes in the headwaters of the Yangtze River will change the streamflow variability, which will ultimately impact the hydropower supply and water resources of the Yangtze Basin. This study contributes to the understanding of the dynamics of the hydrological cycle and may lead to better hydrologic system modeling for downstream water resource developments
Preverbs: an introduction
The notion âpreverbâ is a traditional descriptive notion in Indo-European linguistics. It refers to morphemes that appear
in front of a verb, and which form a close semantic unit with that verb. In many cases, the morpheme that functions as a preverb
can also function without a preverbal context, often as an adverb or an adposition. Most linguists use the notion âpreverbâ
as a cover term for preverbal words and preverbal prefixes. The preverb may be separated from the verb whilst retaining its
close cohesion with the verb, which is called âtmesisâ. It may also develop into a bound morpheme, that is, a prefix inseparable
from the verb, with concomitant reduction of phonological form in some cases. If the preverb has become a real prefix, we
may use the more specific notion of âcomplex verbâ, whereas we take the notion âcomplex predicateâ to refer generally to multi-morphemic
expressions with verbal valency. That is, we make a terminological distinction between complex predicates and complex verbs.
The latter are multi-morphemic, but behave as single grammatical words
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