Cardiovascular and hormonal responses to electroconvulsive therapy.

A patient suffering from severe psychiatric depression underwent a course of electroconvulsive therapy. A marked rise in systemic arterial pressure, heart rate and plasma catecholamines in response to electroconvulsive therapy was attenuated by Β-receptor blockade using propranolol. The significance and mechanism of this attenuation are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72273/1/j.1365-2044.1981.tb08818.x.pd

Low-angle misorientation dependence of the optical properties of InGaAs/InAlAs quantum wells

We investigate the dependence of the low-temperature photoluminescence linewidths from InP-lattice-matched InGaAs/InAlAs quantum wells on the low-angle misorientation from the (100) surface of the host InP substrate. Quantum wells were grown on InP substrates misorientated by 0, 0.2, 0.4 and 0.6 degrees; 0.4 degrees was found to consistently result in the narrowest peaks, with the optimal spectral purity of ~4.25 meV found from a 15nm quantum well. The width of the emission from the 15nm quantum well was used to optimize the growth parameters. Thick layers of Si-doped InGaAs were then grown and found to have bulk, low temperature (77 K), electron mobilities up to \mu ~ 3.5 x 10^4 cm2/Vs with an electron concentration of ~1 x 10^16

Experimental testing of grouted connections for offshore substructures: a critical review

Grouted connections have been extensively used in the oil and gas industry for decades, and more recently their application has been extended to the offshore wind industry. Unfortunately plain-pipe grouted connections for large-diameter monopile foundations have recently exhibited clear signs of insufficient axial capacity, resulting in slippage between the transition piece and monopile. Motivated by the emergence of such problems, this paper presents a critical review of the technical literature related to the experimental testing for grouted connections for offshore substructures, covering all the key material and design parameters that influence their capacity, including the confinement provided by pile and sleeve, surface finish, simultaneous bending action, connection length, dynamic loading, early-age cycling during grout curing, grout shrinkage, radial pre-stress and temperature. The review also focuses on the relevance of such parameters for offshore wind applications and addresses what needs to be considered to ensure that their design achieves the desired capacity, behaviour and efficiency

Prediction of wear in grouted connections for offshore wind turbine generators

Insufficient axial capacity of large-diameter plain-pipe grouted connections has recently been observed in offshore wind turbine substructures across Europe. Aimed at understanding the implications of this phenomenon, a campaign of structural condition monitoring was undertaken. The measurements showed significant axial displacements occurring between the transition piece and the monopile, which in turn resulted in a considerable amount of wear. Given the existing lack of technical data on the implications that this relative movement has on the wear of grouted connections, a methodology was developed to quantify the likely risk to the foundation integrity of the wear failure mode. The proposed approach consists of a numerical model which applies the wear rate derived from previous experimental testing to the conditions experienced by typical offshore grouted connections, as indicated by the wind turbine generators' supervisory control and data acquisition systems. The output of this model showed that, for a representative sample of the wind farm substructures analysed as a case study, the accumulated lifetime wear would be minimal in the majority of the grouted connection, i.e. less than 0.4 mm over 75% of the connection, but a much greater loss in thickness, of the order of 4 mm, was predicted at the very top and bottom of the connection. This assessment is based on the assumptions that no significant changes occur in the surrounding environmental conditions and that the degradation in the grouted connection does not significantly affect the dynamic response of the foundation structure over its life span. Importantly, these assumptions may affect the model's predictions in terms of cumulated wear over time, not in terms of identifying the individual connections to be prioritised when performing remedial work, which is indeed the main intended use of the model

Experimental investigation on the development of wear in grouted connections for offshore wind turbine generators

Relative displacements between grout and steel have been observed in grouted connections used for offshore wind turbine substructures, which appear to be linked to the unexpected settlements that have occurred in some offshore wind farms. A literature review has highlighted a lack of understanding of the implications that this relative movement has on the grout wear. Experimentation has therefore been undertaken to determine the influence of various factors on the wear development, including compressive stress, displacement amplitude, surface roughness and the presence of water, looking at conditions typically experienced by offshore grouted connections. These experiments have indicated that wear of the steel and grout surfaces occur, even at low magnitude compressive stresses. The presence of water has the most significant impact on wear rate, being up to 18 times higher than for the equivalent dry condition. The presence of water can also significantly reduce the coefficient of friction to values lower than typically recommended for evaluation of grouted connections. These findings demonstrate that wear of the grouted connection is likely to occur over the life of this type of offshore structures and should therefore be considered when evaluating their integrity and assessing their behaviour

Modelling deadlock in open restricted queueing networks

Open restricted queueing networks give rise to the phenomenon of deadlock, whereby some customers may be unable to ever leave a server due to mutual blocking. This paper explores deadlock in queueing networks with limited queueing capacity, presents a method of detecting deadlock in discrete event simulations, and builds Markov chain models of these deadlocking networks. The three networks for which Markov models are given include single and multi-server networks for one and two node systems. The expected times to deadlock of these models are compared to results obtained using a simulation of the stochastic process, together with the developed deadlock detection method. This paper aims to be of value to simulation modellers of queues

Using high-frequency phosphorus monitoring for water quality management: a case study of the upper River Itchen, UK

Increased concentrations of phosphorus (P) in riverine systems lead to eutrophication and can contribute to other environmental effects. Chalk rivers are known to be particularly sensitive to elevated P levels. We used high-frequency (daily) automatic water sampling at five distinct locations in the upper River Itchen (Hampshire, UK) between May 2016 and June 2017 to identify the main P species (including filterable reactive phosphorus, total filterable phosphorus, total phosphorus and total particulate phosphorus) present and how these varied temporally. Our filterable reactive phosphorus (considered the biologically available fraction) data were compared with the available Environment Agency total reactive phosphorus (TRP) values over the same sampling period. Over the trial, the profiles of the P fractions were complex; the major fraction was total particulate phosphorus with the mean percentage value ranging between 69 and 82% of the total P present. Sources were likely to be attributable to wash off from agricultural activities. At all sites, the FRP and Environment Agency TRP mean concentrations over the study were comparable. However, there were a number of extended time periods (1 to 2 weeks) where the mean FRP concentration (e.g. 0.62 mg L−1) exceeded the existing regulatory values (giving a poor ecological status) for this type of river. Often, these exceedances were missed by the limited regulatory monitoring procedures undertaken by the Environment Agency. There is evidence that these spikes of elevated concentrations of P may have a biological impact on benthic invertebrate (e.g. blue-winged olive mayfly) communities that exist in these ecologically sensitive chalk streams. Further research is required to assess the ecological impact of P and how this might have implications for the development of future environmental regulations

Hyperbaric pressure of 51 atmospheres is without effect on the depression of oxygen uptake in kidney tissue culture produced by halothane

Although anesthetized animals are awakened when subjected to increased pressure, compression does not result in antagonism of all phenomena associated with these drugs. It has recently been demonstrated that halothane's inhibition of respiration of isolated rat liver mitochondria is not reversed by hydraulic compression to 51 atmospheres. In order to determine whether this phenomenon can be extrapolated to the whole cell, we have investigated the effect of hydraulic compression of intact renal cells equilibrated with halothane, and conclude that pressure does not overcome the inhibitory effect of this anesthetic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25565/1/0000107.pd

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

Northern Europe and the UK experienced an exceptionally warm and wet winter in 2019/20, driven by an anomalously positive North Atlantic Oscillation (NAO). This positive NAO was well forecast by several seasonal forecast systems, suggesting that this winter the NAO was highly predictable at seasonal lead times. A very strong positive Indian Ocean dipole (IOD) event was also observed at the start of winter. Here we use composite analysis and model experiments, to show that the IOD was a key driver of the observed positive NAO. Using model experiments that perturb the Indian Ocean initial conditions, two teleconnection pathways of the IOD to the north Atlantic emerge: a tropospheric teleconnection pathway via a Rossby wave train travelling from the Indian Ocean over the Pacific and Atlantic, and a stratospheric teleconnection pathway via the Aleutian region and the stratospheric polar vortex. These pathways are similar to those for the El Niño Southern Oscillation link to the north Atlantic which are already well documented. The anomalies in the north Atlantic jet stream location and strength, and the associated precipitation anomalies over the UK and northern Europe, as simulated by the model IOD experiments, show remarkable agreement with those forecast and observed