7,459 research outputs found
Sign switch of Gaussian bending modulus for microemulsions; a self-consistent field analysis exploring scale invariant curvature energies
Bending rigidities of tensionless balanced liquid-liquid interfaces as
occurring in microemulsions are predicted using self-consistent field theory
for molecularly inhomogeneous systems. Considering geometries with scale
invariant curvature energies gives unambiguous bending rigidities for systems
with fixed chemical potentials: The minimal surface Im3m cubic phase is used to
find the Gaussian bending rigidity, , and a torus with Willmore
energy allows for direct evaluation of the mean bending modulus,
. Consistent with this, the spherical droplet gives access to . We observe that tends to be negative for strong
segregation and positive for weak segregation; a finding which is instrumental
for understanding phase transitions from a lamellar to a sponge-like
microemulsion. Invariably, remains positive and increases with
increasing strength of segregation.Comment: 7 pages, 5 figure
Multiorder neurons for evolutionary higher-order clustering and growth
This letter proposes to use multiorder neurons for clustering irregularly shaped data arrangements. Multiorder neurons are an evolutionary extension of the use of higher-order neurons in clustering. Higher-order neurons parametrically model complex neuron shapes by replacing the classic synaptic weight by higher-order tensors. The multiorder neuron goes one step further and eliminates two problems associated with higher-order neurons. First, it uses evolutionary algorithms to select the best neuron order for a given problem. Second, it obtains more information about the underlying data distribution by identifying the correct order for a given cluster of patterns. Empirically we observed that when the correlation of clusters found with ground truth information is used in measuring clustering accuracy, the proposed evolutionary multiorder neurons method can be shown to outperform other related clustering methods. The simulation results from the Iris, Wine, and Glass data sets show significant improvement when compared to the results obtained using self-organizing maps and higher-order neurons. The letter also proposes an intuitive model by which multiorder neurons can be grown, thereby determining the number of clusters in data
Concentration in Knowledge Output:A Case of Economics Journals
Journals moderate knowledge activity in economics. The activity of publishing article in professional journal forms significant part of knowledge output. Output of economics articles has been growing over the time. We examine an important question: Is there any case of institutional or location concentration in knowledge production? This paper analyses concentration indicators specific to economics journals and explores link between publication process and concentration. The analysis of various concentration measures present evidence for institutional-geographic-area-author concentration in Knowledge production in Economics. High concentration levels indicate possibility of institutional lock-in. The literature provides evidence for myopic refereeing, editorial favouritism and the presence of ‘lock-in’ effect. The achievement in journal publication is influenced by factors like institutional affiliation, propitious circumstances etc. Discussion carried out in this paper hints the possibility of causal link between unfair process and unfair outcome.Knowledge,Lotka's Law,Fourier Series
Yang-Mills equation for stable Higgs sheaves
We establish a Kobayashi-Hitchin correspondence for the stable Higgs sheaves
on a compact Kaehler manifold. Using it, we also obtain a Kobayashi-Hitchin
correspondence for the stable Higgs G-sheaves, where G is any complex reductive
linear algebraic group
Dynamic Nuclear Polarization in Silicon Microparticles
We report record high Si-29 spin polarization obtained using dynamic nuclear
polarization in microcrystalline silicon powder. Unpaired electrons in this
silicon powder are due to dangling bonds in the amorphous region of this
intrinsically heterogeneous sample. Si-29 nuclei in the amorphous region become
polarized by forced electron-nuclear spin flips driven by off-resonant
microwave radiation while nuclei in the crystalline region are polarized by
spin diffusion across crystalline boundaries. Hyperpolarized silicon
microparticles have long T1 relaxation times and could be used as tracers for
magnetic resonance imaging.Comment: 4 pages, 5 figures, published versio
Universal Control of Nuclear Spins Via Anisotropic Hyperfine Interactions
We show that nuclear spin subsystems can be completely controlled via
microwave irradiation of resolved anisotropic hyperfine interactions with a
nearby electron spin. Such indirect addressing of the nuclear spins via
coupling to an electron allows us to create nuclear spin gates whose
operational time is significantly faster than conventional direct addressing
methods. We experimentally demonstrate the feasibility of this method on a
solid-state ensemble system consisting of one electron and one nuclear spin.Comment: RevTeX4, 8 pages, 8 figure
Influence of analysis and design models on minimum weight design
The results of numerical experiments designed to illustrate how the minimum weight design, accuracy, and cost can be influenced by: (1) refinement of the finite element analysis model and associated load path problems, and (2) refinement of the design variable linking model are examined. The numerical experiments range from simple structures where the modelling decisions are relatively obvious and less costly to the more complex structures where such decisions are less obvious and more costly. All numerical experiments used employ the dual formulation in ACCESS-3 computer program. Guidelines are suggested for creating analysis and design models that predict a minimum weight structure with greater accuracy and less cost. These guidelines can be useful in an interactive optimization environment and in the design of heuristic rules for the development of knowledge-based expert optimization systems
Observation of a 2D Bose-gas: from thermal to quasi-condensate to superfluid
We present experimental results on a Bose gas in a quasi-2D geometry near the
Berezinskii, Kosterlitz and Thouless (BKT) transition temperature. By measuring
the density profile, \textit{in situ} and after time of flight, and the
coherence length, we identify different states of the gas. In particular, we
observe that the gas develops a bimodal distribution without long range order.
In this state, the gas presents a longer coherence length than the thermal
cloud; it is quasi-condensed but is not superfluid. Experimental evidence
indicates that we observe the superfluid transition (BKT transition).Comment: 5 pages, 6 figure
Experimental evidence on promotion of electric and improved biomass cookstoves.
Improved cookstoves (ICS) can deliver "triple wins" by improving household health, local environments, and global climate. Yet their potential is in doubt because of low and slow diffusion, likely because of constraints imposed by differences in culture, geography, institutions, and missing markets. We offer insights about this challenge based on a multiyear, multiphase study with nearly 1,000 households in the Indian Himalayas. In phase I, we combined desk reviews, simulations, and focus groups to diagnose barriers to ICS adoption. In phase II, we implemented a set of pilots to simulate a mature market and designed an intervention that upgraded the supply chain (combining marketing and home delivery), provided rebates and financing to lower income and liquidity constraints, and allowed households a choice among ICS. In phase III, we used findings from these pilots to implement a field experiment to rigorously test whether this combination of upgraded supply and demand promotion stimulates adoption. The experiment showed that, compared with zero purchase in control villages, over half of intervention households bought an ICS, although demand was highly price-sensitive. Demand was at least twice as high for electric stoves relative to biomass ICS. Even among households that received a negligible price discount, the upgraded supply chain alone induced a 28 percentage-point increase in ICS ownership. Although the bundled intervention is resource-intensive, the full costs are lower than the social benefits of ICS promotion. Our findings suggest that market analysis, robust supply chains, and price discounts are critical for ICS diffusion
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