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This is a copy of the slides presented at the meeting but not formally written up for the volume.
Description: Semiconductor physics contains a rich body of theory and working designs. However, their material properties seem to be reaching their limits. Perovskite oxides on the other hand have abundant physical properties, but are still under active investigation. The advent of RHEED-monitoring of pulsed laser deposition allows for the fabrication of structures with single unit cell (4 Å) thick layers. In this way we may be able to fabricate quantum well structures for both applications and fundamental investigations. Superlattices of the Mott insulator LaTiO3 (LTO) and the band gap insulator SrTiO3 (STO) form such a structure. The superlattices are metallic, both as-grown and post-annealed . This has been attributed to the existence of metallic states at the interfaces between LTO and STO . At these interfaces the electron density is found to extend about 10 Å into the STO. However, theoretically, the required length scale for quantum confinement is of the order of 4 Å. A possible way to increase this confinement is to use a buffer material with a larger band gap than that of LTO (similar to semiconductor band gap engineering) and/or with a lower dielectric constant . LaAlO3 (LAO) is such a material (ΔELAO = 5.6 eV vs. ΔESTO = 3.2 eV, εLAO = 24 vs. εSTO = 300). Here we report on the growth of LTO/LAO superlattices on STO substrates. As-grown superlattices of LTO/LAO are metallic, while post-annealing turns them insulating. This may be explained from a disorder-order transition in a 2D Mott-Hubbard model . XPS and EELS measurements of the titanium valence show interesting differences for LTO layers close to and far away from the sample surface. The former, for thin LAO capping layers, show the presence of Ti4+ while the latter only have Ti3+. Hard XPS of samples with varying capping layer thickness shows an exponential dependence of the Ti3+ contents on a length scale of about 5 unit cells.  A. Ohtomo et al., Nature 419, 378-380 (2002).  S. Okamoto & A.J. Millis, Phys. Rev. B 70, 075101 (2004).  D. Heidarian & N. Trivedi, Phys. Rev. Lett. 93, 126401 (2004).
We consider a spherical variant of the Faraday problem, in which a spherical drop is subjected to a time-periodic body force, as well as surface tension. We use a full three-dimensional parallel front-tracking code to calculate the interface motion of the parametrically forced oscillating viscous drop, as well as the velocity field inside and outside the drop. Forcing frequencies are chosen so as to excite spherical harmonic wavenumbers ranging from 1 to 6. We excite gravity waves for wavenumbers 1 and 2 and observe translational and oblate–prolate oscillation, respectively. For wavenumbers 3 to 6, we excite capillary waves and observe patterns analogous to the Platonic solids. For low viscosity, both subharmonic and harmonic responses are accessible. The patterns arising in each case are interpreted in the context of the theory of pattern formation with spherical symmetry.
After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.
In this study, an improved fluid–structure interaction (FSI) analysis method is developed for a flapping wing. A co-rotational (CR) shell element is developed for its structural analysis. Further, a relevant non-linear dynamic formulation is developed based on the CR framework. Three-dimensional preconditioned Navier–Stokes equations are employed for its fluid analysis. An implicit coupling scheme is employed to combine the structural and fluid analyses. An explicit investigation of a 3D plunging wing is conducted using this FSI analysis method. A further investigation of this plunging wing is performed in relation to its operating condition. In addition, the relation between the wing’s aerodynamic performance and plunging motion is investigated.
BACKGROUND: Meningiomas are the most common primary benign brain tumors in adults. Given the extended life expectancy of most meningiomas, consideration of quality of life (QOL) is important when selecting the optimal management strategy. There is currently a dearth of meningioma-specific QOL tools in the literature. OBJECTIVE: In this systematic review, we analyze the prevailing themes and propose toward building a meningioma-specific QOL assessment tool. METHODS: A systematic search was conducted, and only original studies based on adult patients were considered. QOL tools used in the various studies were analyzed for identification of prevailing themes in the qualitative analysis. The quality of the studies was also assessed. RESULTS: Sixteen articles met all inclusion criteria. Fifteen different QOL assessment tools assessed social and physical functioning, psychological, and emotional well-being. Patient perceptions and support networks had a major impact on QOL scores. Surgery negatively affected social functioning in younger patients, while radiation therapy had a variable impact. Any intervention appeared to have a greater negative impact on physical functioning compared to observation. CONCLUSION: Younger patients with meningiomas appear to be more vulnerable within social and physical functioning domains. All of these findings must be interpreted with great caution due to great clinical heterogeneity, limited generalizability, and risk of bias. For meningioma patients, the ideal QOL questionnaire would present outcomes that can be easily measured, presented, and compared across studies. Existing scales can be the foundation upon which a comprehensive, standard, and simple meningioma-specific survey can be prospectively developed and validated.
The flow in a decelerating turbulent round jet is investigated using direct numerical simulation. The simulations are initialised with a flow field from a statistically stationary turbulent jet. Upon stopping the inflow, a deceleration wave passes through the jet, behind which the velocity field evolves towards a new statistically unsteady self-similar state. Assumption of unsteady self-similar behaviour leads to analytical relations concerning the evolution of the centreline mean axial velocity and the shapes of the radial profiles of the velocity statistics. Consistency between these predictions and the simulation data supports the use of the assumption of self-similarity. The mean radial velocity is predicted to reverse in direction near to the jet centreline as the deceleration wave passes, contributing to an approximately threefold increase in the normalised mass entrainment rate. The shape of the mean axial velocity profile undergoes a relatively small change across the deceleration transient, and this observation provides direct evidence in support of previous models that have assumed that the mean axial velocity profile, and in some cases also the jet spreading angle, remain approximately constant within unsteady jets.
Previous research has shown relatively diminished medial prefrontal cortex activation and heightened psychophysiological responses during the recollection of personal events in post-traumatic stress disorder (PTSD), but the origin of these abnormalities is unknown. Twin studies provide the opportunity to determine whether such abnormalities reflect familial vulnerabilities, result from trauma exposure, or are acquired characteristics of PTSD.
In this case–control twin study, 26 male identical twin pairs (12 PTSD; 14 non-PTSD) discordant for PTSD and combat exposure recalled and imagined trauma-unrelated stressful and neutral life events using a standard script-driven imagery paradigm during functional magnetic resonance imaging and concurrent skin conductance measurement.
Diminished activation in the medial prefrontal cortex during Stressful v. Neutral script-driven imagery was observed in the individuals with PTSD, relative to other groups.
Diminished medial prefrontal cortex activation during Stressful v. Neutral script-driven imagery may be an acquired characteristic of PTSD. If replicated, this finding could be used prospectively to inform diagnosis and the assessment of treatment response.
Fluid residence time is a key concept in the understanding and design of chemically reacting flows. In order to investigate how turbulent mixing affects the residence time distribution within a flow, this study examines statistics of fluid residence time from a direct numerical simulation (DNS) of a statistically stationary turbulent round jet with a jet Reynolds number of 7290. The residence time distribution in the flow is characterised by solving transport equations for the residence time of the jet fluid and for the jet fluid mass fraction. The product of the jet fluid residence time and the jet fluid mass fraction, referred to as the mass-weighted stream age, gives a quantity that has stationary statistics in the turbulent jet. Based on the observation that the statistics of the mass fraction and velocity are self-similar downstream of an initial development region, the transport equation for the jet fluid residence time is used to derive a model describing a self-similar profile for the mean of the mass-weighted stream age. The self-similar profile predicted is dependent on, but different from, the self-similar profiles for the mass fraction and the axial velocity. The DNS data confirm that the first four moments and the shape of the one-point probability density function of mass-weighted stream age are indeed self-similar, and that the model derived for the mean mass-weighted stream-age profile provides a useful approximation. Using the self-similar form of the moments and probability density functions presented it is therefore possible to estimate the local residence time distribution in a wide range of practical situations in which fluid is introduced by a high-Reynolds-number jet of fluid.
The enhanced error monitoring in patients with obsessive–compulsive disorder (OCD), typically measured with the error-related negativity (ERN), has been found to be temporally stable and independent of symptom expression. Here, we examined whether the error monitoring in patients with OCD could be experimentally modulated by individually tailored symptom provocation.
Twenty patients with OCD and 20 healthy controls performed a flanker task in which OCD-relevant or neutral pictures were presented prior to a flanker stimulus. An individualized stimulus set consisting of the most provoking images in terms of OCD symptoms was selected for each patient with OCD. Response-locked event-related potentials were recorded and used to examine the error-related brain activity.
Patients with OCD showed larger ERN amplitudes than did control subjects in both the OCD-symptom provocation and neutral conditions. Additionally, while patients with OCD exhibited a significant increase in the ERN under the OCD-symptom provocation condition when compared with the neutral condition, control subjects showed no variation in the ERN between the conditions.
Our results strengthen earlier findings of hyperactive error monitoring in OCD, as indexed by higher ERN amplitudes in patients with OCD than in controls. Importantly, we showed that the patients’ overactive error-signals were experimentally enhanced by individually tailored OCD-symptom triggers, thus suggesting convincing evidence between OCD-symptoms and ERN. Such findings imply that therapeutic interventions should target affective regulation in order to alleviate the perceived threatening value of OCD triggers.
What makes a government legitimate? Why do people voluntarily comply with laws, even when no one is watching? The idea of political legitimacy captures the fact that people obey when they think governments' actions accord with valid principles. For some, what matters most is the government's performance on security and the economy. For others, only a government that follows democratic principles can be legitimate. Political legitimacy is therefore a two-sided reality that scholars studying the acceptance of governments need to take into account. The diversity and backgrounds of East Asian nations provides a particular challenge when trying to determine the level of political legitimacy of individual governments. This book brings together both political philosophers and political scientists to examine the distinctive forms of political legitimacy that exist in contemporary East Asia. It is essential reading for all academic researchers of East Asian government, politics and comparative politics.
A political order enjoys legitimacy when its citizens or subjects have reason to believe that its claim to power is based on rightful authority, and its exercise of power can be justified according to accepted principles or norms. Political legitimacy is thus always a two-sided affair; intrinsically, it entails both empirical and normative dimensions. Understood from an empirical or sociological point of view, a state or regime is legitimate to the extent that its people accept its authority and see its actions as justifiable according to reasons they accept as valid. The normative dimension of legitimacy concerns the question of whether the norms by which the political order justifies its power ought to be regarded as valid norms. A state can enjoy sociological legitimacy without meeting coherent criteria of normative legitimacy. A state that can be rationally justified according to a particular conception of normative legitimacy may not be legitimate in the eyes of its people if they do not embrace the normative premises that underwrite this justification. To fully understand the dynamics of political legitimation in a given context requires attentiveness to both its empirical and normative aspects.
Yet despite repeated admonitions from scholars who study political legitimacy, most scholarly work on the concept tends to address its normative and empirical dimensions as separate enterprises. Political philosophers seek to identify the principles for evaluating the moral justifiability of political power. Empirical social scientists investigate the factors behind a people's acceptance or rejection of political elites’ claims to govern. Neither approach seems to be entirely satisfactory on its own. A purely normative approach that abstracts away from particular contexts in constructing an ideal theory of legitimacy is vulnerable to the challenge that it has little practical relevance. Legitimacy is about power relations between rulers and ruled; surely a consideration of the reasons that motivate agents in a particular order is relevant to evaluating the legitimacy of power relations in that order. Likewise, a social scientific approach that takes citizens’ statements of support for a state as indicators of political legitimacy has not shed much light on the state's legitimacy or illegitimacy if it has not also probed the normative principles according to which they believe the state's actions to be justified.
The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continent- and ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.
Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in glacier melt independently from model output. Here, we present a comprehensive database of Greenland glacier surface mass-balance observations from the ablation area of the ice sheet and local glaciers. The database spans the 123 a from 1892 to 2015, contains a total of ~3000 measurements from 46 sites, and is openly accessible through the PROMICE web portal (http://www.promice.dk). For each measurement we provide X, Y and Z coordinates, starting and ending dates as well as quality flags. We give sources for each entry and for all metadata. Two thirds of the data were collected from grey literature and unpublished archive documents. Roughly 60% of the measurements were performed by the Geological Survey of Denmark and Greenland (GEUS, previously GGU). The data cover all regions of Greenland except for the southernmost part of the east coast, but also emphasize the importance of long-term time series of which there are only two exceeding 20 a. We use the data to analyse uncertainties in point measurements of surface mass balance, as well as to estimate surface mass-balance profiles for most regions of Greenland.
Membranes for selective water vapor separation were assembled from graphene oxide suspension using techniques compatible with high volume industrial production. The large-diameter graphene oxide flake suspensions were synthesized from graphite materials via relatively efficient chemical oxidation steps with attention paid to maintaining flake size and achieving high graphene oxide concentrations. Graphene oxide membranes produced using scalable casting methods exhibited water vapor flux and water/nitrogen selectivity performance meeting or exceeding that of membranes produced using vacuum-assisted laboratory techniques. (PNNL-SA-117497)