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Dissociable hormonal profiles for psychopathology and stress in anorexia and bulimia nervosa
No full textBackgroundAnorexia nervosa (AN) and bulimia nervosa (BN) are complex psychiatric conditions, in which both psychological and metabolic factors have been implicated. Critically, the experience of stress can precipitate loss-of-control eating in both conditions, suggesting an interplay between mental state and metabolic signaling. However, associations between psychological states, symptoms and metabolic processes in AN and BN have not been examined.MethodsEighty-five women (n = 22 AN binge/purge subtype, n = 33 BN, n = 30 controls) underwent remote salivary cortisol sampling and a 2-day, inpatient study session to examine the effect of stress on cortisol, gut hormones [acyl-ghrelin, peptide tyrosine tyrosine (PYY) and glucagon-like peptide-1] and food consumption. Participants were randomized to either an acute stress induction or control task on each day, and plasma hormones were serially measured before a naturalistic, ad libitum meal.ResultsCortisol-awakening response was augmented in AN but not in BN relative to controls, with body mass index explaining the most variance in post-awakening cortisol (36%). Acute stress increased acyl-ghrelin and PYY in AN compared to controls; however, stress did not alter gut hormone profiles in BN. Instead, a group-by-stress interaction showed nominally reduced cortisol reactivity in BN, but not in AN, compared to controls. Ad libitum consumption was lower in both patient groups and unaffected by stress.ConclusionsFindings extend previous reports of metabolic dysfunction in binge-eating disorders, identifying unique associations across disorders and under stress. Moreover, we observed disrupted homeostatic signaling in AN following psychological stress, which may explain, in part, the maintenance of dysregulated eating in this serious illness
Evaluating the business case for continuous manufacturing of pharmaceuticals: A supply network perspective
No full textThis chapter addresses the challenges of evaluating the business case for continuous manufacturing of pharmaceuticals, looking beyond traditional technical assessments made at the unit operations or individual production facility level. It provides an overview of key concepts, approaches, and tools for the early assessment of supply network configuration opportunities enabled by continuous production processing interventions. Multiple levels of analysis are considered with the aid of examples based on major UK research programs on continuous production process technologies. Particular emphasis is placed on the potential for achieving enhanced product flexibility (in terms of volume and variety) and, depending on scale, the optimum number and location of manufacturing operations to support speed to market and system-level cost benefits. In the case of multiple manufacturing operations using continuous production process technologies, where production facility replication through digital twins is becoming a key enabler, the chapter sets out a supply network design and analysis approach that evaluates the commercial and operational viability of alternative manufacturing supply network scenarios
Overview of H-Formulation: A Versatile Tool for Modeling Electromagnetics in High-Temperature Superconductor Applications
No full textThis paper reviews the modeling of high-temperature superconductors (HTS) using the finite-element method (FEM) based on the -formulation of Maxwell's equations. This formulation has become the most popular numerical modeling method for simulating the electromagnetic behavior of HTS, especially thanks to the easiness of implementation in the commercial finite-element program COMSOL Multiphysics. Numerous studies prove that the -formulation is able to simulate a wide scope of HTS topologies, from simple geometries such as HTS tapes and coils, to more complex HTS devices, up to large superconducting magnets. In this paper, we review the basics of the -formulation, its evolution from 2D to 3D, its application for calculating critical currents and AC losses as well as magnetization of HTS bulks and tape stacks. We also review the use of the -formulation for large-scale HTS applications, its use to solve multi-physics problems involving electromagnetic-thermal and electromagnetic-mechanical couplings, and its application to study the dynamic resistance of superconductors and flux pumps
Practical Limits to Common Mode Rejection in Mode Localized Weakly Coupled Resonators
No full textThe amplitude ratio output metric in mode localized weakly coupled resonators has been established to show superior rejection of first order temperature and pressure variations over frequency shift output metric. This work for the first time documents a holistic study on the temperature dependence of amplitude ratio and frequency shift output metric over various operating points of a mode localized resonator while comparing different modes of operation and different coupling schemes. The results show that both modes of an electrically coupled resonator system exhibit approx 10times improvement in rejecting temperature fluctuations over the modes of similar mechanically coupled resonators. Both mechanically coupled and electrically coupled resonators showed an improvement of 2-3 orders of magnitude common mode rejection as compared to the frequency shift output. For the first time, a comparison was made between amplitude ratio and differential frequency measurements and the results showed similar rejection capabilities between the two output metrics. The various mechanisms leading to the temperature dependence of the three output metrics are discussed in detail thus highlighting the advantages of using each of them for sensing and timing applications
Erratum: Sensitivity analysis of thermoacoustic instability with adjoint Helmholtz solvers (Physical Review Fluids (2018) 3 (110509) DOI: 10.1103/PhysRevFluids.3.110509)
No full textA subsequent paper [1] shows that the conclusion that refers to the Rayleigh criterion should, instead, refer to the first variation of the Rayleigh criterion. The sentences of the paper that need to be altered are listed below. The rest of the paper is unaffected. In the Abstract, (1) “Physical interpretation of these results shows that the well-known Rayleigh criterion should be revised for a linear analysis ... the criterion should contain the adjoint pressure rather than the pressure.” should be changed to “These results show that the first variation of the Rayleigh criterion should be formed with the adjoint pressure rather than the direct pressure.” In Sec. I, (1) “This quote will be reexamined in Sec. VIII in light of the results in this paper” should be removed. (2) “(vi): the conclusion that Rayleigh's criterion needs to be revised for non-self-adjoint systems” should be removed. In Sec. VIII, The results in this section are correct but concern the first variation of Chu's expanded Rayleigh criterion, rather than Chu's expanded Rayleigh criterion itself. (3) “In the self-adjoint case, this becomes equivalent to Rayleigh's criterion” is no longer relevant. (4) “This differs from Chu's statement [3] because” should be changed to “The first variation of Chu's statement [3] requires that.” (5) “In a linear stability analysis,” should be replaced by “When considering the first variation,” (6) “the Rayleigh integral formed with the adjoint pressure” should be changed to “the integral formed with the adjoint pressure.” In Sec. XI, (1) “For this reason, the quote from Chu [3]... is not correct for non-self-adjoint systems.” should be removed. (2) “For the same reason, the generalized Rayleigh criterion should be formed with the adjoint pressure. The Rayleigh criterion formed with the direct pressure is the special case for self-adjoint systems.” should be changed to “The first variation of the Rayleigh criterion should be formed with the adjoint pressure. The first variation formed with the direct pressure is the special case for self-adjoint systems.
Effect of spark location and laminar flame speed on the ignition transient of a premixed annular combustor
No full textThe flame expansion process (“light-round”) during the ignition transient in annular combustors depends on a number of parameters such as equivalence ratio (and hence laminar burning velocity, SL, of the mixture), turbulent intensity, mean flow magnitude and direction, geometry, and spark location. Here, an experimental study on a fully premixed, swirled, bluff body stabilised annular combustor is carried out to identify the sensitivity of the light-round to these parameters. A wide range of conditions were assessed: two inter-burner spacing distances, two fuels (methane and ethylene), bulk velocities from 10 to 30 m/s, and ϕ between 0.75 and 1 for methane and 0.58 and 0.9 for ethylene. The spark location was varied longitudinally (x/D = 0.5 and x/D = 5, where D is the bluff body diameter, expected to lie inside and downstream of the inner recirculation zone of a single burner, respectively) and azimuthally. The propagation of the flame during the ignition transient was investigated via high speed (10 kHz) OH* chemiluminescence using two cameras to simultaneously image the annular chamber from axially downstream and from the side of the combustor. The pattern of flame propagation depended on the initial longitudinal spark location and comprised of burner-to-burner propagation close to the bluff bodies and upstream propagation of the flame front. The spark azimuthal position, in this horizontal configuration, had a negligible impact on the light-round time (τLR), thus buoyancy plays a minor role in the process. In contrast, sparking at x/D = 5 resulted in an increase in τLR by ~ 30–40% for all the conditions examined. The inter-burner spacing had a negligible effect on τLR. When increasing bulk velocity, τLR decreased. For a constant bulk velocity, τLR depended strongly on SL and it was found that mixtures with the same SL from different fuels resulted in the same τLR. Further, the observed propagation speed, corrected for dilatation, was approximately proportional to SL and was within 30% of estimates of the turbulent flame speed at the same conditions. These findings suggest that SL is one of the controlling parameters of the light-round process; hence turbulent flame propagation has a major role in the light-round process, in addition to dilatation and flame advection by the mean flow. The results reported in the study help explain the mechanism of light-round and can assist the development of efficient ignition procedures in aviation gas turbines
Imposing virtual origins on the velocity components in direct numerical simulations
No full textThe relative wall-normal displacement of the origin perceived by different components of near-wall turbulence is known to produce a change in drag. This effect is produced for instance by drag-reducing surfaces of small texture-size like riblets and superhydrophobic surfaces. To facilitate the research on how these displacements alter near-wall turbulence, this paper studies different strategies to model such displacement effect through manipulated boundary conditions. Previous research has considered the effect of offsetting the virtual origins perceived by the tangential components of the velocity from the reference, boundary plane, where the wall-normal velocity was set to zero. These virtual origins are typically characterised by slip-length coefficients in Robin, slip-like boundary conditions. In this paper, we extend this idea and explore several techniques to define and implement virtual origins for all three velocity components on direct numerical simulations (DNSs) of channel flows, with special emphasis on the wall-normal velocity. The aim of this work is to provide a suitable foundation to extend the existing understanding on how these virtual origins affect the near-wall turbulence, and ultimately aid in the formulation of simplified models that capture the effect of complex surfaces on the overlying flow and on drag, without the need to resolve fully the turbulence and the surface texture. From the techniques tested, Robin boundary conditions for all three velocities are found to be the most satisfactory method to impose virtual origins, relating the velocity components to their respective wall-normal gradients linearly. Our results suggest that the effect of virtual origins on the flow, and hence the change in drag that they produce, can be reduced to an offset between the virtual origin perceived by the mean flow and that perceived by the overlying turbulence, and that turbulence remains otherwise smooth-wall-like, as proposed by Luchini (1996). The origin for turbulence, however, would not be set by the spanwise virtual origin alone, but by a combination of the spanwise and wall-normal origins. These observations suggest the need for an extension of Luchini's virtual-origin theory to predict the change in drag, accounting for the wall-normal transpiration when its effect is not negligible
Effect of channel thickness on noise in organic electrochemical transistors
No full textOrganic electrochemical transistors (OECTs) have been widely used as transducers in electrophysiology and other biosensing applications. Their identifying characteristic is a transconductance that increases with channel thickness, and this provides a facile mechanism to achieve high signal amplification. However, little is known about their noise behavior. Here, we investigate noise and extract metrics for the signal-to-noise ratio and limit of detection in OECTs with different channel thicknesses. These metrics are shown to improve as the channel thickness increases, demonstrating that OECTs can be easily optimized to show not only high amplification, but also low noise
Cortical-like dynamics in recurrent circuits optimized for sampling-based probabilistic inference
No full textSensory cortices display a suite of ubiquitous dynamical features, such as ongoing noise variability, transient overshoots and oscillations, that have so far escaped a common, principled theoretical account. We developed a unifying model for these phenomena by training a recurrent excitatory–inhibitory neural circuit model of a visual cortical hypercolumn to perform sampling-based probabilistic inference. The optimized network displayed several key biological properties, including divisive normalization and stimulus-modulated noise variability, inhibition-dominated transients at stimulus onset and strong gamma oscillations. These dynamical features had distinct functional roles in speeding up inferences and made predictions that we confirmed in novel analyses of recordings from awake monkeys. Our results suggest that the basic motifs of cortical dynamics emerge as a consequence of the efficient implementation of the same computational function—fast sampling-based inference—and predict further properties of these motifs that can be tested in future experiments
Secure optical communication using a quantum alarm.
No full textOptical fibre networks are advancing rapidly to meet growing traffic demands. Security issues, including attack management, have become increasingly important for optical communication networks owing to the vulnerabilities associated with tapping light from optical fibre link. Physical layer security often requires restricting access to the channel and periodic inspection of the link performance. In this paper, we report how quantum communication techniques can be utilized to detect a physical layer attack. We present an efficient method for monitoring the physical layer security of a high data rate classical optical communication network using a modulated continuous variable quantum signal. We describe the theoretical and experimental underpinnings of this monitoring system, and the monitoring accuracy for different monitored parameters. We analyse its performance in both unamplified and amplified optical links. The technique represents a novel approach in applying quantum signal processing to practical optical communication networks and compares well with classical monitoring methods. We conclude by discussing the challenges in its practical application, its difference with existing quantum key distribution, and its usage in future secure optical transport network planning