2,073 research outputs found
The Value of Comparative Animal Research : Kroghâs Principle Facilitates Scientific Discoveries
There are no conflicts of interest to declare. This paper developed from the 2016 Early Career Impact Award from the Federation of Associations in Behavioral & Brain Sciences to TJS. TJS has received funding from The Leverhulme Trust. FJPE is in receipt of funding from the BBSRC (BB/M001555/1). The National Institutes of Health has funded RDF (NS 034950, NS093277, NIMH 087930), AGO (HD079573, IOS-1354760) and AMK (HD081959). BAA is an Arnold O. Beckman postdoctoral fellow.Peer reviewedPostprin
Confinement-controlled Water Engenders High Energy Density Electrochemical-double-layer Capacitance
The renewable energy sector critically needs low-cost and environmentally
neutral energy storage solutions throughout the entire device life cycle.
However, the limited performance of standard water-based electrochemical
systems prevents their use in certain applications. Meanwhile, recent
fundamental studies revealed dielectric anomalies of water near solid-liquid
interfaces of carbon-based nanomaterials. In contrast to the bulk water
properties, these anomalies of water under nano-confinement and in the presence
of electric fields have not yet been understood and used. Here, we
experimentally study the ability of the interfacial water layer to engender and
store charge in electrochemical double-layer capacitance. We demonstrate the
first prototype of a water-only membrane-electrode assembly. The prototype
exhibits characteristics comparable to existing batteries and supercapacitors
without using electrolytes as ionic carriers. The results provide the impetus
for the development of high-energy-density electrochemical double-layer
capacitors and open up other avenues for ecologically-neutral batteries, fuel
cells, and nanofluidic devices
Non-perturbative approach for the time-dependent symmetry breaking
We present a variational method which uses a quartic exponential function as
a trial wave-function to describe time-dependent quantum mechanical systems. We
introduce a new physical variable which is appropriate to describe the
shape of wave-packet, and calculate the effective action as a function of both
the dispersion and . The effective potential
successfully describes the transition of the system from the false vacuum to
the true vacuum. The present method well describes the long time evolution of
the wave-function of the system after the symmetry breaking, which is shown in
comparison with the direct numerical computations of wave-function.Comment: 8 pages, 3 figure
Confinement-Controlled Water Engenders Unusually High Electrochemical Capacitance
The electrodynamics of nanoconfined water have been shown to change dramatically compared to bulk water, opening room for safe electrochemical systems. We demonstrate a nanofluidic âwater-onlyâ battery that exploits anomalously high electrolytic properties of pure water at firm confinement. The device consists of a membrane electrode assembly of carbon-based nanomaterials, forming continuously interconnected water-filled nanochannels between the separator and electrodes. The efficiency of the cell in the 1â100 nm pore size range shows a maximum energy density at 3 nm, challenging the region of the current metal-ion batteries. Our results establish the electrodynamic fundamentals of nanoconfined water and pave the way for low-cost and inherently safe energy storage solutions that are much needed in the renewable energy sector
Inclusive B-Meson Production in e^+ e^- and p p-bar Collisions
We provide nonperturbative fragmentation functions for B mesons, both at
leading and next-to-leading order in the MS-bar factorization scheme with five
massless quark flavors. They are determined by fitting the fractional energy
distribution of B mesons inclusively produced in e^+ e^- annihilation at CERN
LEP1. Theoretical predictions for the inclusive production of B mesons with
high transverse momenta in p p-bar scattering obtained with these fragmentation
functions nicely agree, both in shape and normalization, with data recently
taken at the Fermilab Tevatron.Comment: 20 pages (Latex), 6 figures (Postscript
Microbial Lag Phase can be Indicative of, or Independent From, Cellular Stress
Measures of microbial growth, used as indicators of cellular stress, are sometimes quantified at a single time-point. In reality, these measurements are compound representations of length of lag, exponential growth-rate, and other factors. Here, we investigate whether length of lag phase can act as a proxy for stress, using a number of model systems (Aspergillus penicillioides; Bacillus subtilis; Escherichia coli; Eurotium amstelodami, E. echinulatum, E. halophilicum, and E. repens; Mrakia frigida; Saccharomyces cerevisiae; Xerochrysium xerophilum; Xeromyces bisporus) exposed to mechanistically distinct types of cellular stress including low water activity, other solute-induced stresses, and dehydration-rehydration cycles. Lag phase was neither proportional to germination rate for X. bisporus (FRR3443) in glycerol-supplemented media (r2â=â0.012), nor to exponential growth-rates for other microbes. In some cases, growth-rates varied greatly with stressor concentration even when lag remained constant. By contrast, there were strong correlations for B. subtilis in media supplemented with polyethylene-glycol 6000 or 600 (r2â=â0.925 and 0.961), and for other microbial species. We also analysed data from independent studies of food-spoilage fungi under glycerol stress (Aspergillus aculeatinus and A. sclerotiicarbonarius); mesophilic/psychrotolerant bacteria under diverse, solute-induced stresses (Brochothrix thermosphacta, Enterococcus faecalis, Pseudomonas fluorescens, Salmonella typhimurium, Staphylococcus aureus); and fungal enzymes under acid-stress (Terfezia claveryi lipoxygenase and Agaricus bisporus tyrosinase). These datasets also exhibited diversity, with some strong- and moderate correlations between length of lag and exponential growth-rates; and sometimes none. In conclusion, lag phase is not a reliable measure of stress because length of lag and growth-rate inhibition are sometimes highly correlated, and sometimes not at all
Interpretation and the Constraints on International Courts
This paper argues that methodologies of interpretation do not do what they promise â they do not constrain interpretation by providing neutral steps that one can follow in finding out a meaning of a text â but nevertheless do their constraining work by being part of what can be described as the legal practice
Life Beyond the Solar System: Space Weather and Its Impact on Habitable Worlds
The search of life in the Universe is a fundamental problem of astrobiology
and a major priority for NASA. A key area of major progress since the NASA
Astrobiology Strategy 2015 (NAS15) has been a shift from the exoplanet
discovery phase to a phase of characterization and modeling of the physics and
chemistry of exoplanetary atmospheres, and the development of observational
strategies for the search for life in the Universe by combining expertise from
four NASA science disciplines including heliophysics, astrophysics, planetary
science and Earth science. The NASA Nexus for Exoplanetary System Science
(NExSS) has provided an efficient environment for such interdisciplinary
studies. Solar flares, coronal mass ejections and solar energetic particles
produce disturbances in interplanetary space collectively referred to as space
weather, which interacts with the Earth upper atmosphere and causes dramatic
impact on space and ground-based technological systems. Exoplanets within close
in habitable zones around M dwarfs and other active stars are exposed to
extreme ionizing radiation fluxes, thus making exoplanetary space weather (ESW)
effects a crucial factor of habitability. In this paper, we describe the recent
developments and provide recommendations in this interdisciplinary effort with
the focus on the impacts of ESW on habitability, and the prospects for future
progress in searching for signs of life in the Universe as the outcome of the
NExSS workshop held in Nov 29 - Dec 2, 2016, New Orleans, LA. This is one of
five Life Beyond the Solar System white papers submitted by NExSS to the
National Academy of Sciences in support of the Astrobiology Science Strategy
for the Search for Life in the Universe.Comment: 5 pages, the white paper was submitted to the National Academy of
Sciences in support of the Astrobiology Science Strategy for the Search for
Life in the Univers
New phase diagrams for dense carbon-oxygen mixtures and white dwarf evolution
Cool white dwarfs are reliable and independent stellar chronometers. The most
common white dwarfs have carbon-oxygen dense cores. Consequently, the cooling
ages of very cool white dwarfs sensitively depend on the adopted phase diagram
of the carbon-oxygen binary mixture. A new phase diagram of dense carbon-oxygen
mixtures appropriate for white dwarf interiors has been recently obtained using
direct molecular dynamics simulations. In this paper, we explore the
consequences of this phase diagram in the evolution of cool white dwarfs. To do
this we employ a detailed stellar evolutionary code and accurate initial white
dwarf configurations, derived from the full evolution of progenitor stars. We
use two different phase diagrams, that of Horowitz et al. (2010), which
presents an azeotrope, and the phase diagram of Segretain & Chabrier (1993),
which is of the spindle form. We computed the evolution of 0.593 and 0.878M_sun
white dwarf models during the crystallization phase, and we found that the
energy released by carbon-oxygen phase separation is smaller when the new phase
diagram of Horowitz et al. (2010) is used. This translates into time delays
that are on average a factor about 2 smaller than those obtained when the phase
diagram of Segretain & Chabrier (1993) is employed. Our results have important
implications for white dwarf cosmochronology, because the cooling ages of very
old white dwarfs are different for the two phase diagrams. This may have a
noticeable impact on the age determinations of very old globular clusters, for
which the white dwarf color-magnitude diagram provides an independent way of
estimating their age.Comment: 7 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Testing the Universality of Fragmentation Functions
Using fragmentation functions for charged pions, charged kaons, and
(anti)protons recently extracted from experimental data of e^+e^- annihilation
at the Z-boson resonance and at centre-of-mass energy root(s) = 29 GeV, we
perform a global study of inclusive charged-hadron production in p anti-p,
gamma p, and gamma gamma collisions at next-to-leading order in the parton
model of quantum chromodynamics. Comparisons of our results with p anti-p data
from CERN S p anti-p S and the Fermilab Tevatron, gamma p data from DESY HERA,
and gamma gamma data from CERN LEP2 allow us to test the universality of the
fragmentation functions predicted by the factorization theorem. Furthermore, we
perform comparisons with (e^+e^-)-annihilation data from LEP2 so as to test the
scaling violations predicted by the Altarelli-Parisi evolution equations.Comment: 35 pages (Latex), 15 figures (Postscript
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