2,246 research outputs found
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Experimental determination of layer cloud edge charging from cosmic ray ionisation
The cloud-air transition zone at stratiform cloud edges is an electrically active region where droplet charging has been predicted. Cloud edge droplet charging is expected from vertical flow of cosmic ray generated atmospheric ions in the global electric circuit. Experimental confirmation of stratiform cloud edge electrification is presented here, through charge and droplet measurements made within an extensive layer of supercooled stratiform cloud, using a specially designed electrostatic sensor. Negative space charge up to 35 pC m−3 was found in a thin (<100 m) layer at the lower cloud boundary associated with the clear air-cloud conductivity gradient, agreeing closely with space charge predicted from the measured droplet concentration using ion-aerosol theory. Such charge levels carried by droplets are sufficient to influence collision processes between cloud droplets
Remote sensing of cloud base charge
Layer clouds are abundant in the Earth's atmosphere. Such clouds do not
become sufficiently strongly charged to generate lightning, but they show weak
charging along the upper and lower cloud boundaries where there is a
conductivity transition. Cloud edge charging has recently been observed using
balloon-carried electrometers. Measurement of cloud boundary charging without
balloons is shown to be possible here for low altitude (<1km) charged cloud
bases, through combining their effect on the surface electric field with laser
time of flight cloud base height measurements, and the application of simple
electrostatic models.Comment: Proceedings of the Electrostatics Society of America conference,
Ottawa, June 201
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Observations of Saharan dust layer electrification
Electrification of atmospheric dust influences the coagulation, wet removal and fall speeds of dust particles. Alignment of dust particles can also occur in fair weather atmospheric electrical conditions if the particles are charged. However, very few electrical measurements made in elevated dust layers exist. Balloon-borne charge and particle instrumentation have been used to investigate the electrical properties of elevated Saharan dust layers. Soundings from the Cape Verde Islands, which experience frequent Saharan dust outbreaks, intercepted several dust layers. Two balloon soundings during summer 2009 detected dust particles in layers up to 4 km altitude. Simultaneous electrical measurements showed charge inside the dust layers, with a maximum measured charge density of 25 pC m − 3, sufficient to influence wet removal processes
Trace element and isotope constraints on crustal anatexis by upwelling mantle melts in the North Atlantic Igneous Province: an example form the Isle of Rum, NW Scotland
Sr and Nd isotope ratios, together with lithophile trace elements, have been measured in a representative set of igneous rocks and Lewisian gneisses from the Isle of Rum in order to unravel the petrogenesis of the felsic rocks that erupted in the early stages of Palaeogene magmatism in the North Atlantic Igneous Province (NAIP). The Rum rhyodacites appear to be the products of large amounts of melting of Lewisian amphibolite gneiss. The Sr and Nd isotopic composition of the magmas can be explained without invoking an additional granulitic crustal component. Concentrations of the trace element Cs in the rhyodacites strongly suggests that the gneiss parent rock had experienced Cs and Rb loss prior to Palaeogene times, possibly during a Caledonian event. This depletion caused heterogeneity with respect to 87Sr/86Sr in the crustal source of silicic melts. Other igneous rock types on Rum (dacites, early gabbros) are mixtures of crustalmelts and and primarymantle melts. Forward Rare Earth Element modelling shows that late stage picritic melts on Rum are close analogues for the parent melts of the Rum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss.
These primary mantle melts have close affinities to Mid-Oceanic Ridge Basalts (MORB), whose trace element content varies from slightly depleted to slightly enriched. Crustal anatexis is a common process
in the rift-to-drift evolution during continental break-up and the formation of Volcanic Rifted Margins
systems. The ‘early felsic–later mafic’ volcanic rock associations from Rum are compared to similar
associations recovered from the now-drowned seaward-dipping wedges on the shelf of SE Greenland
and on the Vøring Plateau (Norwegian Sea). These three regions show geochemical differences that
result from variations in the regional crustal composition and the depth at which crustal anatexis took
place
Missing in Action? Electronic Gaming Machines in Gambling Studies Research
In the past thirty years casinos across the world have become dominated by the rise of “electronic gaming machines” (EGMs). Expanding with tremendous speed, this technology has arguably become the dominant form of non-online gambling around the world at time of writing (DeMichele, 2017; Schwartz, 2018). EGMs are also noted as being one of the most harmful forms of gambling, with significant numbers of players betting beyond their financial limits (MacLaren et al, 2012; Stewart & Wohl, 2013), spending a disproportionate amount of time playing (Cummings, 1999; Ballon, 2005; Schüll, 2012; cf. Dickerson, 1996), becoming disconnected from the world outside of the “zone” (Schüll, 2012) of gambling play, and even becoming bankrupt or otherwise financially crippled as a result of their use (Petry, 2003; Scarf et al, 2011). Using metadata from Web of Science and Scopus databases, we analysed peer-reviewed gambling research produced in Australia, New Zealand, North America and the UK published between 1996 and 2016. Surprisingly, we found that the overwhelming of majority of articles do not specifically address EGMs as the most popular and pervasive gambling technology available. Our paper teases out some concerning implications of this finding for the interdisciplinary field of gambling studies
On the Fixed-Point Structure of Scalar Fields
In a recent Letter (K.Halpern and K.Huang, Phys. Rev. Lett. 74 (1995) 3526),
certain properties of the Local Potential Approximation (LPA) to the Wilson
renormalization group were uncovered, which led the authors to conclude that
dimensional scalar field theories endowed with {\sl non-polynomial}
interactions allow for a continuum of renormalization group fixed points, and
that around the Gaussian fixed point, asymptotically free interactions exist.
If true, this could herald very important new physics, particularly for the
Higgs sector of the Standard Model. Continuing work in support of these ideas,
has motivated us to point out that we previously studied the same properties
and showed that they lead to very different conclusions. Indeed, in as much as
the statements in hep-th/9406199 are correct, they point to some deep and
beautiful facts about the LPA and its generalisations, but however no new
physics.Comment: Typos corrected. A Comment - to be published in Phys. Rev. Lett. 1
page, 1 eps figure, uses LaTeX, RevTex and eps
Momentum Scale Expansion of Sharp Cutoff Flow Equations
We show how the exact renormalization group for the effective action with a
sharp momentum cutoff, may be organised by expanding one-particle irreducible
parts in terms of homogeneous functions of momenta of integer degree (Taylor
expansions not being possible). A systematic series of approximations -- the
approximations -- result from discarding from these parts, all terms
of higher than the degree. These approximations preserve a field
reparametrization invariance, ensuring that the field's anomalous dimension is
unambiguously determined. The lowest order approximation coincides with the
local potential approximation to the Wegner-Houghton equations. We discuss the
practical difficulties with extending the approximation beyond .Comment: 31 pages including 5 eps figures, uses harvmac and epsf. Minor
additions -- not worth the bandwidth if you already have a cop
I\u27ve always been outspoken on what I think can be improved : An Interview with Dr. Garry J. Smith
Dr. Garry J. Smith has spent many years at the forefront of critical gambling research in Canada. In this interview he talks about the genesis of the Alberta Gambling Research Institute, how sociology brings a different lens to gambling studies than psychology, why he speaks out against certain aspects of commercial gambling, the relationship between fun and fairness, and the critical gaps in research that need to be added to address the inherent conflicts of interest that occur with self-regulated gambling.
The interview was conducted by academics Fiona Nicoll and Mark R Johnson on 29 November, 2017. A transcript of the conversation was edited for publication. As part of this process, both interviewers and the interviewee were invited to edit their remarks
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Fair weather criteria for atmospheric electricity measurements
The global atmospheric electric circuit, which links the space environment with terrestrial weather, has mostly been investigated using fair-weather surface atmospheric electricity measurements. Retrieving global circuit information, however, requires the selection of “fair weather” data, to avoid local meteorological disturbances. The research results presented here challenge the applicability of long-standing definitions of electrically fair weather atmospheric conditions. From detailed new measurements and theory, three improved requirements (FW1 to FW3) for fair weather atmospheric electricity conditions are described. These are: (FW1) absence of hydrometeors, aerosol and haze, as apparent through the visual range exceeding 2 km, (FW2) negligible cumuliform cloud and no extensive stratus cloud with cloud base below 1500 m, and (FW3) surface wind speed between 1 m s−1 and 8 m s−1. Automatic and manual measurement approaches to identifying these requirements are given. Through applying these criteria at the many measurements sites now operating, the noise from meteorological variability will be reduced, leading to data more representative of the global electric circuit
On Truncations of the Exact Renormalization Group
We investigate the Exact Renormalization Group (ERG) description of (
invariant) one-component scalar field theory, in the approximation in which all
momentum dependence is discarded in the effective vertices. In this context we
show how one can perform a systematic search for non-perturbative continuum
limits without making any assumption about the form of the lagrangian.
Concentrating on the non-perturbative three dimensional Wilson fixed point, we
then show that the sequence of truncations , obtained by expanding
about the field and discarding all powers and
higher, yields solutions that at first converge to the answer obtained without
truncation, but then cease to further converge beyond a certain point. No
completely reliable method exists to reject the many spurious solutions that
are also found. These properties are explained in terms of the analytic
behaviour of the untruncated solutions -- which we describe in some detail.Comment: 15 pages (with figures), Plain TeX, uses psfig, 5 postscript figures
appended as uuencoded compressed tar file, SHEP 93/94-23, CERN-TH.7281/94.
(Corrections of typos, and small additions to improve readability: version to
be published in Phys. Lett. B
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