Experiments Concerning Nonequilibrium Conductivity in a Seeded Plasma

Measurements of conductivity have been made in a plasma composed of argon seeded with potassium vapor. The gas temperature was 2000°K; the pressure, 1 atm; and the potassium concentration was between 0.22 and 0.80 mole-percent. Conductivity values, calculated from a two-temperature model in which the energy dependence of the cross sections and radiation losses from the plasma are taken into account, agree well with experimental values. Measured values of the plasma temperature appear to be about 10% less than predicted values. Relaxation times for the conductivity in response to a step function change in the electric field were proportional to (n_e0l/σ_0E^2) and were a few tens of microseconds for a field strength in the range 3 to 10 v/cm. The ionization rate appeared to be limited primarily by the heating rate for the plasma, and the short relaxation times suggest that ionization occurs by a multistep process. Analysis of conductivity and light intensity data obtained during the transient period indicates that the electron temperature approaches its final value during the first few microseconds

Turbulence and turbulent mixing in natural fluids

Turbulence and turbulent mixing in natural fluids begins with big bang turbulence powered by spinning combustible combinations of Planck particles and Planck antiparticles. Particle prograde accretions on a spinning pair releases 42% of the particle rest mass energy to produce more fuel for turbulent combustion. Negative viscous stresses and negative turbulence stresses work against gravity, extracting mass-energy and space-time from the vacuum. Turbulence mixes cooling temperatures until strong-force viscous stresses freeze out turbulent mixing patterns as the first fossil turbulence. Cosmic microwave background temperature anisotropies show big bang turbulence fossils along with fossils of weak plasma turbulence triggered as plasma photon-viscous forces permit gravitational fragmentation on supercluster to galaxy mass scales. Turbulent morphologies and viscous-turbulent lengths appear as linear gas-proto-galaxy-clusters in the Hubble ultra-deep-field at z~7. Proto-galaxies fragment into Jeans-mass-clumps of primordial-gas-planets at decoupling: the dark matter of galaxies. Shortly after the plasma to gas transition, planet-mergers produce stars that explode on overfeeding to fertilize and distribute the first life.Comment: 23 pages 12 figures, Turbulent Mixing and Beyond 2009 International Center for Theoretical Physics conference, Trieste, Italy. Revision according to Referee comments. Accepted for Physica Scripta Topical Issue to be published in 201

Space- and Time-Efficient Algorithm for Maintaining Dense Subgraphs on One-Pass Dynamic Streams

While in many graph mining applications it is crucial to handle a stream of updates efficiently in terms of {\em both} time and space, not much was known about achieving such type of algorithm. In this paper we study this issue for a problem which lies at the core of many graph mining applications called {\em densest subgraph problem}. We develop an algorithm that achieves time- and space-efficiency for this problem simultaneously. It is one of the first of its kind for graph problems to the best of our knowledge. In a graph $G = (V, E)$, the "density" of a subgraph induced by a subset of nodes $S \subseteq V$ is defined as $|E(S)|/|S|$, where $E(S)$ is the set of edges in $E$ with both endpoints in $S$. In the densest subgraph problem, the goal is to find a subset of nodes that maximizes the density of the corresponding induced subgraph. For any $\epsilon>0$, we present a dynamic algorithm that, with high probability, maintains a $(4+\epsilon)$-approximation to the densest subgraph problem under a sequence of edge insertions and deletions in a graph with $n$ nodes. It uses $\tilde O(n)$ space, and has an amortized update time of $\tilde O(1)$ and a query time of $\tilde O(1)$. Here, $\tilde O$ hides a O(\poly\log_{1+\epsilon} n) term. The approximation ratio can be improved to $(2+\epsilon)$ at the cost of increasing the query time to $\tilde O(n)$. It can be extended to a $(2+\epsilon)$-approximation sublinear-time algorithm and a distributed-streaming algorithm. Our algorithm is the first streaming algorithm that can maintain the densest subgraph in {\em one pass}. The previously best algorithm in this setting required $O(\log n)$ passes [Bahmani, Kumar and Vassilvitskii, VLDB'12]. The space required by our algorithm is tight up to a polylogarithmic factor.Comment: A preliminary version of this paper appeared in STOC 201

Three-body structure of the nnΛnn\Lambda system with ΛN−ΣN\Lambda N-\Sigma N coupling

The structure of the three-body $nn\Lambda$ system, which has been observed recently by the HypHI collaboration, is investigated taking $\Lambda N-\Sigma N$ coupling explicitly into account. The $YN$ and $NN$ interactions employed in this work reproduce the binding energies of $^3_{\Lambda}$H, $^4_{\Lambda}$H and $^4_{\Lambda}$He. We do not find any $^3_{\Lambda}n$ bound state, which contradicts the interpretation of the data reported by the HypHI collaboration.Comment: To be publsihed in PRC as a Rapid communicatio

The influence of the preparation method of NiOx photocathodes on the efficiency of p-type dye-sensitised solar cells

Improving the efficiency of p-type dye-sensitized solar cells (DSCs) is an important part of the development of high performance tandem DSCs. The optimization of the conversion efficiency of p-DSCs could make a considerable contribution in the improvement of solar cells at a molecular level. Nickel oxide is the most widely used material in p-DSCs, due to its ease of preparation, chemical and structural stability, and electrical properties. However, improvement of the quality and conductivity of NiO based photocathodes needs to be achieved to bring further improvements to the solar cell efficiency. The subject of this review is to consider the effect of the preparation of NiO surfaces on their efficiency as photocathodes. (C) 2015 Elsevier B.V. All rights reserved

A critical perspective on stigma in physiotherapy: the example of weight stigma

"Manipulating practices is the first ever collection of critical physiotherapy studies and comes at a time of unprecedented change in the profession. Written as a collaboration between 20 authors, many members of the Critical Physiotherapy Network (CPN), the book uncovers the growing body of critical thinking now emerging in physiotherapy. From topics as diverse as 21st century education, ethics, evidence-based practice, touch, and equine therapy; and approaches as varied as disability and performance studies, feminism, logic, narrative theory, new materialism, and phenomenology, the book explores ways of thinking ‘otherwise’ about physiotherapy. Over 16 chapters written by authors from six different countries, Manipulating practices offers insights from some of physiotherapy’s most radical thinkers. The book is also an innovative venture into open source publishing, making it entirely free to download and read. In keeping with the objectives of the CPN, the chapters expose a range of concepts, ideas and practices to critical scrutiny, and reflect the profession’s growing interest in critiquing taken-for-granted ways of practicing and thinking. Manipulating practices will be of interest to clinicians, lecturers, policy-makers, researchers and students, and will provide new impetus to help physiotherapists imagine how the profession might grow and develop into the future.""«Manipulating practices» er den første vitenskapelige antologien som samler kritiske studier innen fysioterapi, og lanseres i en tid der profesjonen er preget av store forandringer. Antologien representerer et samarbeidsprosjekt mellom 20 forskere, hvor majoriteten er medlemmer av Critical Physiotherapy Network (CNP) – et internasjonalt nettverk av forskere og klinikere fra hele verden. Antologien synliggjør den økende tendensen til kritisk tenkning som er i ferd med å vokse frem innenfor fysioterapi. Gjennom å fokusere på varierte tema som utdanning, etikk, evidensbasert praksis, berøring og terapiridning, samt en bred tilnærming som inkluderer funksjonshemming, performance-studier, feminisme, logikk, narrativ teori, ny materialisme og fenomenologi, utforsker antologien nye og annerledes tanker om fysioterapi som fag og profesjon. Antologiens 16 kapitler er skrevet av forskere fra seks ulike land og gir innsikt i forskningen til noen av de mest radikale forskerne i det internasjonale fysioterapimiljøet. Boken er også innovativ gjennom at den publiseres som open access, hvilket betyr at den kan lastes ned og leses gratis og dermed gjøres allment tilgjengelig. I tråd med ambisjonen for CPN, utforskes en rekke ulike begreper, ideer og praktiske tilnærminger relatert til kritisk tenkning innenfor fysioterapi. Slik gjenspeiles også profesjonens økende interesse for å kritisere etablerte måter å praktisere og tenke på, som tidligere har vært tatt for gitt. «Manipulating practices» vil være av interesse for forskere, klinikere, forelesere, politikere og studenter. Antologien vil forhåpentligvis bidra med nye impulser med henblikk på hvordan fysioterapiprofesjonen vil vokse og utvikle seg fremover.

Connections Between Adaptive Control and Optimization in Machine Learning

This paper demonstrates many immediate connections between adaptive control and optimization methods commonly employed in machine learning. Starting from common output error formulations, similarities in update law modifications are examined. Concepts in stability, performance, and learning, common to both fields are then discussed. Building on the similarities in update laws and common concepts, new intersections and opportunities for improved algorithm analysis are provided. In particular, a specific problem related to higher order learning is solved through insights obtained from these intersections.Comment: 18 page

Understanding the role of promoters in catalysis: operando XAFS/DRIFTS study of CeO_x/Pt/Al₂O₃ during CO oxidation

A combined operando XAFS/DRIFTS study on CeOx/Pt/Al2O3 catalysts has been performed during CO oxidation and provides insights into the changes in nanoparticle structure and adsorbed species during the reaction profile. The onset of CO2 formation is shown to be concurrent with a rapid re-oxidation of the Pt nanoparticles, evidenced by XAFS spectroscopy, and the loss of bridge bonded CO adsorbed on Pt, as shown by simultaneous DRIFTS acquisition. The continued appearance of linear bound CO on the catalyst surface is shown to remain long after catalytic light off. The interaction of Pt and CeOx is evidenced by the improved performance towards CO oxidation, compared to the non-CeOx modified Pt/Al2O3, and changes in the CO adsorption properties on Pt previously linked to Pt-CeO2 interfaces