69,653 research outputs found
Critical -equivariant biharmonic maps
We study -equivariant biharmonic maps in the critical dimension. A
major consequence of our study concerns the corresponding heat flow. More
precisely, we prove that blowup occurs in the biharmonic map heat flow from
into . To our knowledge, this was the first example of blowup
for the biharmonic map heat flow. Such results have been hard to prove, due to
the inapplicability of the maximum principle in the biharmonic case.
Furthermore, we classify the possible -equivariant biharmonic maps from
into , and we show that there exists, in contrast to the
harmonic map analogue, equivariant biharmonic maps from into
that wind around as many times as we wish. We believe that the ideas
developed herein could be useful in the study of other higher-order parabolic
equations.Comment: 24 pages, 1 figure. Published online in Calculus of Variations and
Partial Differential Equations, 201
Sarah Turner - eco-artist and designer through craft-based upcycling
Sarah Turner is an eco-artist and designer who practices craft-based upcycling with waste plastic bottles and cans to create lighting, sculpture and decorative home interior products. Since 1998, her enthusiasm, creativity and good will have allowed her to gain several high-profile client commissions and to win awards from design, innovation and business competitions. The aim of this portrait is to introduce Sarah’s work and shed light on the resources, knowledge and skills involved in her practice and on the barriers to and drivers for her craft-based upcycling. We consider that Sarah’s work could be one of the stepping stones for a shift towards more sustainable craft practice, both in the United Kingdom and beyond. By exploring the right ingredients for craft-based upcycling, barriers liable to be faced and key drivers that stimulate motivation, we hope that this portrait will inspire and attract more designers and makers to embed upcycling in their future practice
Universal scaling and ferroelectric hysteresis regimes in the giant squid axon propagating action potential: a Phase Space Approach
The experimental data for the giant squid axon propagated action potential is
examined in phase space. Plots of capacitive and ionic currents vs. potential
exhibit linear portions providing temperature dependent time rates and maximum
conductance constants for sodium and Potassium channels. First order phase
transitions of ionic channels are identified. Incorporation of time rates into
Avrami equations for fractions of open channels yields for each channel a
temperature independent dimensionless constant that is close in value to the
fine structure constant. It also reveals temperature independent scaling
exponents. Evidence is presented that the action potential traverses a
ferroelectric hysteresis loop. This results in a second order phase transition
polarization flip at the peak of the action potential, followed by closing of
sodium and opening of potassium channels, and finally closing the loop by
reversing the polarization flip as the resting potential is reached. The
existence of this hysteresis loop for the giant squid action potential suggests
the possibility of neurons with two stable states, the basis for memory storage
and retrieval.Comment: 19 pages, 6 figure
Observation of narrow-band noise accompanying the breakdown of insulating states in high Landau levels
Recent magnetotransport experiments on high mobility two-dimensional electron
systems have revealed many-body electron states unique to high Landau levels.
Among these are re-entrant integer quantum Hall states which undergo sharp
transitions to conduction above some threshold field. Here we report that these
transitions are often accompanied by narrow- and broad-band noise with
frequencies which are strongly dependent on the magnitude of the applied dc
current.Comment: 4 pages, 3 figure
Regional geochemical and geophysical surveys in the Berwyn Dome and adjacent areas, north Wales
This report describes stream sediment and gravity
surveys carried out across the Berwyn Dome and adjacent
areas. The gravity survey confirmed the presence of a
broad regional Bouguer anomaly low in the central part of
the Dome, on which is superimposed several smaller irregular
highs and lows. Some of these local anomalies
possibly reflect small igneous bodies but more detailed
gravity surveys would be needed to determine their form.
Near Corwen the Bryneglwys Fault coincides with a 4.5
mGa1 anomaly but southwards the two features diverge,
suggesting that the density interface is related either to a
splay fault or to the eastern margin of the Lower
Palaeozoic Montgomery trough. Some other structural
trends are weakly reflected on the Bouguer anomaly and
aeromagnetic maps, but there is no clear correlation with
known base metal mineralisation. The Bouguer
anomalies cannot be attributed to particular structures
with any certainty but are probably due to a number of
factors, including variation in the Precambrian basement
and changes in the lithology and thickness of Lower
Palaeozoic sedimentary rocks. There is no evidence for a
large granitic body in Lower Palaeozoic rocks underlying
the mineralisation at Llangynog. The aeromagnetic map
suggests the presence of a magnetic basement at a depth
of 3-4 km centred beneath the northwestern margin of
the Dome.
The stream sediment survey involved the collection of a
- 100 mesh stream sediment, panned concentrate and
water sample from each of the 399 sites sampled. The
sample density was 1 site per 1.5 km*. Cu, Pb, Zn, Ba,
Fe, Mn, Co, V, Cr, Ni, Zr, MO and Sn were determined
in the stream sediments, Cu, Pb, Zn, Ba, Fe, Mn, Ce,
Sn, Sb, Ti, Ni and As in the panned concentrates and Cu,
Pb and Zn in stream waters. Major variations in the
results are related to (i) hydrous oxide precipitation processes,
(ii) contamination from human activities, (iii) base
metal and baryte mineralisation, (iv) monazite concentrations
in panned concentrates, (v) hitherto unrecorded
gold mineralisation and (vi) lithological variations. The
latter were related principally to shale-sandstone variation,
but groups of elements attributable to the presence
of basic intrusions, phosphatic rocks, coal measures,
sandstones, limestones and volcanics were also discerned.
Threshold levels were established from cumulative frequency
curve analysis, and some anomalous sites were examined
in the field. Anomalies did not form prominent
coherent groups and were generally weak and scattered,
with a wide variety of element groupings reflecting a
range of causes. Many anomalous panned concentrates
were examined mineralogically to try to . determine
whether anomalies were related to chemically extreme
background lithologies, contamination, or mineralisation.
All the anomalies were related to one or more of the
major causes of variation, although because of the very
limited amount of follow-up work carried out the precise
cause of many anomalies remains uncertain. No anomaly
is considered to represent a strong prospect but several
deserve further limited investigation, notably those
associated with (i) gold mineralisation in the northwest of
the area, (ii) baryte, perhaps accompanied by base metal
’ mineralisation, associated with Caradocian volcanics and
phosphatic rocks at several localities, (iii) mineralisation
associated with Llandeilian limestones and volcanic rocks
north of Llanrhaeadr, and (iv) copper mineralisation
associated with intrusives near the eastern margin of the
Dome, where survey data is most incomplete
Antenna and radome loss measurements for MFMR and PMIS with appendix on MFMR/PMIS computer programs
The NMSU/PSL radiometer antenna calibration facility is described, and the antenna and radome loss measurements made on the passive microwave imaging system and the multifrequency microwave radiometer are summarized. Antenna/radome data reduction techniques, estimation of sky brightness temperatures, and bucket performance tests are presented along with radiometer computer programs
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Cultures within a culture: the role of nationality and religion for environmentally significant behaviour in students living in university accommodation
Reducing global warming cannot be achieved through technological interventions alone; it requires a change in human behaviour. Households are a major contributor to carbon emissions, and thus play an integral part in strategies aiming at a more sustainable living. Behaviour changes in the household can make a significant contribution towards reducing CO2 emissions. However, people vary strongly in their household practices; differences in behaviour account for a substantial amount of variance in heat, electricity, and water consumption (Gill et al., 2010). What causes these differences? In addition to age and education, nationality and religion play a role: They impact on physical aspects of well-being and on environmental attitudes (e.g., Isaacs et al., 2010; Guth et al., 1995). The physical aspect such as perception of warmth is of importance insofar as that comfort practices could influence on environmentally significant behaviour. The Eurobarometer 295 (2008), a study on the attitudes of European citizens towards the environment, also revealed differences in attitudes and behaviour of Europeans towards the environment.
Therefore, steps to promote more sustainable living have to be adapted to different cultures. Rising globalization brings about more heterogeneous populations, meaning that there will be increasingly "cultures within a culture." An important question is what happens to cultural differences in environmentally significant behaviour in such a setting. It could be that differences are diluted by a largely shared environment, or that they continue to persist, thanks to being deeply rooted in one’s origin and to the non-shared part of the environment.
Our study:
The aim of this study was to examine the variation in pro-environmental attitudes, behaviour, and values in members of a community now living in a very similar setting but coming from diverse backgrounds. If personal background accounts for differences in the variables at stake, then this has important implications, e.g. for all national interventions launched to change behaviour.
Data was collected through a web-based survey. The survey was sent out to first-year students living in university accommodation at the University of Greenwich. Religion, strength of religion, nationality, years living in the UK, program studied, gender and age were recorded and the impact of these variables on a variety of measures such as pro- environmental attitudes, values, and actual behaviour was assessed.
Results are currently being analysed but preliminary data suggest that sub-culture does play a role and thus needs to be considered when developing carbon reduction interventions. The implications of these findings for the University and national policies are discussed
Coupled Ferromagnetic and Nematic Ordering of Fermions in an Optical Flux Lattice
Ultracold atoms in Raman-dressed optical lattices allow for effective
momentum-dependent interactions among single-species fermions originating from
short-range s-wave interactions. These dressed-state interactions combined with
very flat bands encountered in the recently introduced optical flux lattices
push the Stoner instability towards weaker repulsive interactions, making it
accessible with current experiments. As a consequence of the coupling between
spin and orbital degrees of freedom, the magnetic phase features Ising nematic
order.Comment: 5 pages, 4 figures (published version
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