Pathways and nerve densities in cerebrovascular innervation

It is gradually becoming clear that cerebrovascular nerves contribute to the control of the cerebral circulation although the knowledge of the functional mechanisms is far from complete. However, many aspects of the morphologic substrate have been identified. The basal cerebral arteries receive sympathetic, parasympathetic and sensory innervation, utilizing the superior cervical and stellate, the pterygopalatine and otic, and the trigeminal ganglia, respectively, as the main peripheral sources. Many of the neural pathways to the cerebral arteries have been elucidated. Those to the supratentorial arterial tree are distributed via the cavernous sinus and surrounding regions. Not only the "classical" neurotransmitters, but also many neuropeptides are found in cerebrovascular nerves. This will lead to new insights since the concepts of cotransmission and neuromodulation have been established now. In the arterial wall, a multilayered organization of nerves has been recognized, consisting of paravascular nerve bundles of passage, a superficial plexus and a terminal plexus located at the adventitial-medial border. Human basal cerebral arteries display a topographical heterogeneity of densities of terminal nerve plexuses. Highest nerve densities are found in arterial segments forming the circle of Willis, in the efferent part of the posterior cerebral artery and in the anterior choroidal artery. Nerve density appears to be determined by locality rather than vascular diameter. Furthermore, local decreases in nerve density are observed with ageing and disease in animals and humans.Biomedical Reviews 1995; 4: 35-46

Optimal location of tsunami warning buoys and sea level monitoring stations in the mediterranean sea

The present study determines the optimal location of detection components of a tsunami warning system in the Mediterranean region given the existing and planned infrastructure. Specifically, we examine the locations of existing tsunameters DART buoys and coastal sea-level monitoring stations to see if additional buoys and stations will improve the proportion of the coastal population that may receive a warning ensuring a timely response. A spreadsheet model is used to examine this issue. Based on the historical record of tsunamis and assuming international cooperation in tsunami detection, it is demonstrated that the existing network of sea level stations and tsunameters enable around ninety percent of the coastal population of the Mediterranean Sea to receive a 15 minute warning. Improvement in this result can be achieved through investment in additional real-time, coastal, sea level monitoring stations. This work was undertaken as a final year undergraduate research project

Specificity of psychopathology across levels of severity:a transdiagnostic network analysis

A prominent hypothesis within the field of psychiatry is that the manifestation of psychopathology changes from non-specific to specific as illness severity increases. Using a transdiagnostic network approach, we investigated this hypothesis in four independent groups with increasing psychopathology severity. We investigated whether symptom domains became more interrelated and formed more clusters as illness severity increased, using empirical tests for two network characteristics: global network strength and modularity-based community detection. Four severity groups, ranging from subthreshold psychopathology to having received a diagnosis and treatment, were derived with a standardized diagnostic interview conducted at age 18.5 (n = 1933; TRAILS cohort). Symptom domains were assessed using the Adult Self Report (ASR). Pairwise comparisons of the symptom networks across groups showed no difference in global network strength between severity groups. Similar number and type of communities detected in the four groups exceeded the more minor differences across groups. Common clusters consisted of domains associated with attention deficit hyperactivity disorder (ADHD) and combined depression and anxiety domains. Based on the strength of symptom domain associations and symptom clustering using a network approach, we found no support for the hypothesis that the manifestation of psychopathology along the severity continuum changes from non-specific to specific

Intervention in the Foreign Exchange Market: Rationale, Effectiveness, Costs and Benefits

This paper reviews the underlying rationale for intervention in the foreign exchange market and argues that intervention can at times be justified due to the market producing the “wrong rate”, to mitigate the effects of exchange rate overshooting and also to slow down the process of economic adjustment. However, in order to be effective foreign exchange market intervention needs to be of the non-sterilized variety, that is, affect the domestic money supply and short term interest rate. Unfortunately, as the case of the Peoples Bank of China and the recent case of the Swiss National Bank’s attempts to stem the appreciation of their currencies, the side effects have shown the rapid expansion of their money supplies and low interest rates have had imposed significant costs on their economies. The result is that the Cemtral Bank has to continually monitor the costs and benefits of their foreign exchange interventions and be prepared consider a return to floating when the costs become too high

CO2 Conversion in Nonuniform Discharges: Disentangling Dissociation and Recombination Mechanisms

Motivated by environmental applications such as synthetic fuel synthesis, plasma-driven conversion shows promise for efficient and scalable gas conversion of CO2 to CO. Both discharge contraction and turbulent transport have a significant impact on the plasma processing conditions, but are, nevertheless, poorly understood. This work combines experiments and modeling to investigate how these aspects influence the CO production and destruction mechanisms in the vortex-stabilized CO2 microwave plasma reactor. For this, a two-dimensional axisymmetric tubular chemical kinetics model of the reactor is developed, with careful consideration of the nonuniform nature of the plasma and the vortex-induced radial turbulent transport. Energy efficiency and conversion of the dissociation process show a good agreement with the numerical results over a broad pressure range from 80 to 600 mbar. The occurrence of an energy efficiency peak between 100 and 200 mbar is associated with a discharge mode transition. The net CO production rate is inhibited at low pressure by the plasma temperature, whereas recombination of CO to CO2 dominates at high pressure. Turbulence-induced cooling and dilution of plasma products limit the extent of the latter. The maxima in energy efficiency observed experimentally around 40% are related to limits imposed by production and recombination processes. Based on these insights, feasible approaches for optimization of the plasma dissociation process are discussed.</p

The effect of organelle discovery upon sub-cellular protein localisation.

Prediction of protein sub-cellular localisation by employing quantitative mass spectrometry experiments is an expanding field. Several methods have led to the assignment of proteins to specific subcellular localisations by partial separation of organelles across a fractionation scheme coupled with computational analysis. Methods developed to analyse organelle data have largely employed supervised machine learning algorithms to map unannotated abundance profiles to known protein–organelle associations. Such approaches are likely to make association errors if organelle-related groupings present in experimental output are not included in data used to create a protein–organelle classifier. Currently, there is no automated way to detect organelle-specific clusters within such datasets. In order to address the above issues we adapted a phenotype discovery algorithm, originally created to filter image-based output for RNAi screens, to identify putative subcellular groupings in organelle proteomics experiments. We were able to mine datasets to a deeper level and extract interesting phenotype clusters for more comprehensive evaluation in an unbiased fashion upon application of this approach. Organelle-related protein clusters were identified beyond those sufficiently annotated for use as training data. Furthermore, we propose avenues for the incorporation of observations made into general practice for the classification of protein–organelle membership from quantitative MS experiments. Biological significance Protein sub-cellular localisation plays an important role in molecular interactions, signalling and transport mechanisms. The prediction of protein localisation by quantitative mass-spectrometry (MS) proteomics is a growing field and an important endeavour in improving protein annotation. Several such approaches use gradient-based separation of cellular organelle content to measure relative protein abundance across distinct gradient fractions. The distribution profiles are commonly mapped in silico to known protein–organelle associations via supervised machine learning algorithms, to create classifiers that associate unannotated proteins to specific organelles. These strategies are prone to error, however, if organelle-related groupings present in experimental output are not represented, for example owing to the lack of existing annotation, when creating the protein–organelle mapping. Here, the application of a phenotype discovery approach to LOPIT gradient-based MS data identifies candidate organelle phenotypes for further evaluation in an unbiased fashion. Software implementation and usage guidelines are provided for application to wider protein–organelle association experiments. In the wider context, semi-supervised organelle discovery is discussed as a paradigm with which to generate new protein annotations from MS-based organelle proteomics experiments. This article is part of a Special Issue entitled: New Horizons and Applications for Proteomics [EuPA 2012]

Numerical model for the determination of the reduced electric field in a CO2 microwave plasma derived by the principle of impedance matching

Three dimensional electromagnetic modelling of a free-standing CO2 microwave plasma has been performed, by describing the plasma as a dielectric medium. The relative permittivity and conductivity of the medium are parametrised. The waveguide geometry from experiment, including the tuner, is put into the model, knowing that this corresponds to maximum power transfer of the microwave generator to the plasma under plasma impedance matching conditions. Two CO2 plasma discharge regimes, differing mainly in pressure, input power and temperature, have been studied. The model\u27s validity has been checked through study of materials of known conductivity. From measurements of the neutral gas temperature and the plasma electron density profile, the reduced electric field is determined. From the parametrisation of the dielectric properties, a range for the effective electron-neutral collision frequency for momentum transfer is estimated. The results for the reduced electric field and the range of the electron neutral collision frequency obtained, are consistent as verified by simulations using BOLSIG+. In addition, from this comparison it is possible to narrow down the range of the collision frequencies, and to estimate the electron temperature. The reduced electric field lies between 80 and 180 Td for the relatively low pressure, low input power, the so-called \u27diffuse\u27 regime. For the relatively high pressure, high input power (\u27contracted\u27) regime it lies between 10 and 60 Td. The normalised collision frequency lies between 1.6 and 2.3 for the diffuse regime, while for the contracted regime it lies between 2 and 3. The electron temperature ranges from 2 to 3 eV for the diffuse regime, and from 0.5 to 1 eV for the contracted regime. Related content: 10.1088/1361-6595/ab1ca1</p

Characterization of the CO2 microwave plasma based on the phenomenon of skin-depth-limited contraction

The subatmospheric CO2 microwave plasma is known to contract to a narrow filament with rising pressure as result of a mode transition. This changing state of contraction is investigated in relation to its dielectric properties, in order to directly relate the discharge parameters to the discharge radius. The electron density and gas temperature are measured, respectively, by 168 GHz microwave interferometry and Doppler broadening of the 777 nm oxygen emission lines. The plasma is operated in steady state with 1400 W at 2.45 GHz, between 100 mbar and 400 mbar. Electron density values in the central region range from 1018 to 1020 m−3 between the discharge modes, while the gas temperature increases from 3000 K to 6500 K, in good agreement with previously reported values. Based on the dielectric properties of the discharge in relation to the plasma radius, it is found that the discharge column constitutes a radius of a single skin depth. Implications of these insights on the conditions of previously reported CO2 dissociation experiments are discussed.</p

Isotope effects in underdoped cuprate superconductors: a quantum phenomenon

We show that the unusual doping dependence of the isotope effects on transition temperature and zero temperature in - plane penetration depth naturally follows from the doping driven 3D-2D crossover, the 2D quantum superconductor to insulator transition (QSI) in the underdoped limit and the change of the relative doping concentration upon isotope substitution. Close to the QSI transition both, the isotope coefficient of transition temperature and penetration depth approach the coefficient of the relative dopant concentration, and its divergence sets the scale. These predictions are fully consistent with the experimental data and imply that close to the underdoped limit the unusual isotope effect on transition temperature and penetration depth uncovers critical phenomena associated with the quantum superconductor to insulator transition in two dimensions.Comment: 6 pages, 3 figure

Insights from the supplementary motor area syndrome in balancing movement initiation and inhibition

The supplementary motor area syndrome is a characteristic neurosurgical syndrome that can occur after unilateral resection of the supplementary motor area. Clinical symptoms may vary from none to a global akinesia, predominantly on the contralateral side, with preserved muscle strength, and mutism. A remarkable feature is that these symptoms completely resolve within weeks to months, leaving only a disturbance in alternating bimanual movements. In this review we give an overview of the old and new insights from the supplementary motor area syndrome and extrapolate these findings to seemingly unrelated diseases and symptoms such as Parkinson’s disease and tics. Furthermore, we integrate findings from lesion, stimulation and functional imaging studies to provide insight in the motor function of the supplementary motor area