1,648 research outputs found
Algal food and fuel coproduction can mitigate greenhouse gas emissions while improving land and water-use efficiency
The goals of ensuring energy, water, food, and climate security can often conflict.Microalgae (algae) are
being pursued as a feedstockfor both food and fuels—primarily due to algae’s high areal yield and ability
to grow on non-arable land, thus avoiding common bioenergy-food tradeoffs. However, algal cultivation
requires significant energy inputs that may limit potential emission reductions.We examine the tradeoffs
associated with producing fuel andfood from algae at the energy–food–water–climate nexus.We use the
GCAM integrated assessment model to demonstrate that algalfood production can promote reductions
in land-use change emissions through the offset of conventional agriculture. However,fuel production,
either via co-production of algal food and fuel or complete biomass conversion to fuel, is necessary to
ensure long-term emission reductions, due to the high energy costs of cultivation. Cultivation of salt–
water algae for food products may lead to substantial freshwater savings; but, nutrients for algae
cultivation will need to be sourced from waste streams to ensure sustainability. By reducing the land
demand of food production, while simultaneously enhancingfood and energy security, algae can further
enable the development of terrestrial bioenergy technologies including those utilizing carbon capture and
storage. Our results demonstrate that large-scale algae research and commercialization efforts should
focus on developing both food and energy products to achieve environmental goals.https://iopscience.iop.org/article/10.1088/1748-9326/11/11/114006/metaPublished versio
Exact Solution of an Evolutionary Model without Ageing
We introduce an age-structured asexual population model containing all the
relevant features of evolutionary ageing theories. Beneficial as well as
deleterious mutations, heredity and arbitrary fecundity are present and managed
by natural selection. An exact solution without ageing is found. We show that
fertility is associated with generalized forms of the Fibonacci sequence, while
mutations and natural selection are merged into an integral equation which is
solved by Fourier series. Average survival probabilities and Malthusian growth
exponents are calculated indicating that the system may exhibit mutational
meltdown. The relevance of the model in the context of fissile reproduction
groups as many protozoa and coelenterates is discussed.Comment: LaTeX file, 15 pages, 2 ps figures, to appear in Phys. Rev.
Hadronic Annihilation Decay Rates of P-wave Heavy Quarkonia with Both Relativistic and QCD Radiative Corrections
Hadronic annihilation decay rates of P-wave heavy quarkonia are given to
next-to-leading order in both and . They include ten
nonperturbative parameters, which can be rigorously defined as the matrix
elements of color-singlet and color-octet operators in NRQCD. We expect these
papameters will be determined from lattice calculations in future.Comment: 5 Pages RevTex. The paper is withdraw
Numerical study of one-dimensional and interacting Bose-Einstein condensates in a random potential
We present a detailed numerical study of the effect of a disordered potential
on a confined one-dimensional Bose-Einstein condensate, in the framework of a
mean-field description. For repulsive interactions, we consider the
Thomas-Fermi and Gaussian limits and for attractive interactions the behavior
of soliton solutions. We find that the disorder average spatial extension of
the stationary density profile decreases with an increasing strength of the
disordered potential both for repulsive and attractive interactions among
bosons. In the Thomas Fermi limit, the suppression of transport is accompanied
by a strong localization of the bosons around the state k=0 in momentum space.
The time dependent density profiles differ considerably in the cases we have
considered. For attractive Bose-Einstein condensates, a bright soliton exists
with an overall unchanged shape, but a disorder dependent width. For weak
disorder, the soliton moves on and for a stronger disorder, it bounces back and
forth between high potential barriers.Comment: 13 pages, 13 figures, few typos correcte
Large Possible retardation effects of quark confinement on the meson spectrum II
We present the results of a study of heavy-light-quark bound states in the
context of the reduced Bethe-Salpeter equation with relativistic vector and
scalar interactions. We find that satisfactory fits may also be obtained when
the retarded effect of the quark-antiquark interaction is concerned.Comment: 11 pages, RevTex, to appear in PR
Possible retardation effects of quark confinement on the meson spectrum
The reduced Bethe-Salpeter equation with scalar confinement and vector gluon
exchange is applied to quark-antiquark bound states. The so called intrinsic
flaw of Salpeter equation with static scalar confinement is investigated. The
notorious problem of narrow level spacings is found to be remedied by taking
into consideration the retardation effect of scalar confinement. Good fit for
the mass spectrum of both heavy and light quarkomium states is then obtained.Comment: 14 pages in LaTex for
Marine microalgae commercial production improves sustainability of global fisheries and aquaculture
publishedVersio
Repetitive elements in parasitic protozoa
A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity
Complete O(v^2) corrections to the static interquark potential from SU(3) gauge theory
For the first time, we determine the complete spin- and momentum-dependent
order v^2 corrections to the static interquark potential from simulations of
QCD in the valence quark approximation at inverse lattice spacings of 2-3 GeV.
A new flavor dependent correction to the central potential is found. We report
a 1/r^2 contribution to the long range spin-orbit potential V_1'. The other
spin-dependent potentials turn out to be short ranged and can be well
understood by means of perturbation theory. The momentum-dependent potentials
qualitatively agree with minimal area law expectations. In view of spectrum
calculations, we discuss the matching of the effective nonrelativistic theory
to QCD as well as renormalization of lattice results. In a first survey of the
resulting bottomonia and charmonia spectra we reproduce the experimental levels
within average errors of 12.5 MeV and 22 MeV, respectively.Comment: 54 pages REVTeX with 24 encapsuled ps figure
Ab Initio Calculation of Relativistic Corrections to the Static Interquark potential I: SU(2) Gauge Theory
We test the capability of state-of-the-art lattice techniques for a precise
determination of relativistic corrections to the static interquark potential,
by use of SU(2) gauge theory. Emphasis is put on the short range structure of
the spin dependent potentials, with lattice resolution a ranging from a approx
0.04 fm (at beta=2.74) down to a approx 0.02 fm (at beta=2.96) on volumes of
32^4 and 48^4 lattice sites. We find a new short range Coulomb-like
contribution to the spin-orbit potential V_1'.Comment: 37 pages REVTeX with 20 encapsuled ps figure
- …