4,578 research outputs found
Renovation of Nitrogenous Wastewater Via Land Application
Removal of inorganic and organic nitrogen from wastewater prior to recharge of ground and surface waters can be accomplished by judicious land application. This study focused attention upon the feasibility of using sprinkler irrigation as the wastewater delivery system with coastal bermudagrass (Cynodon dactylon L.,var. coastal) pasture as the wastewater sink. One site was located on a Sawyer soil near El Dorado, while the other was located on a Savannah soil near Malvern. This report is limited to the renovation of surface waters. Results revealed that nitrogen concentration in runoff water from rainfall was substantially less than nitrogen concentration of the wastewater applied to the soil and similar to background levels. Such results support the consideration of land application as a viable wastewater disposal method
Characterization of 40-Gbit/s pulses generated using a lithium niobate modulator at 1550 nm using frequency resolved optical gating
The characteristics of 40-Gbit/s pulses generated by exploiting the nonlinear characteristics of a Mach-Zender Lithium Niobate modulator are presented. A high spectral resolution frequency resolved optical gating apparatus has been developed to allow for the complete characterization of the intensity and phase of these pulses. The use of these measurements to simplify the design and optimization of an 80-Gbit/s pulse source, based on this 40-Gbit/s source followed by a nonlinear fiber compressor and multiplexer, is also demonstrated
How Barred is the NIR Nearby Universe? An analysis using 2MASS
We determine a firm lower limit to the bar fraction of 0.58 in the nearby
universe using J+H+Ks-band images for 134 spirals from 2MASS. With a mean
deprojected semi-major axis of 5.1 kpc, and a mean deprojected ellipticity of
0.45 this local bar sample lays the ground work for studies on bar formation
and evolution at high redshift.Comment: In the proceedings "Penetrating Bars through Masks of Cosmic Dust:
The Hubble Tuning Fork strikes a New Note
Optimization of optical data transmitters for 40-Gb/s lightwave systems using frequency resolved optical gating
The measurement technique of frequency resolved optical gating has been used to optimize the phase of a 40-GHz train of optical pulses generated using a continuous-wave laser gated with an external modulator. This technique will be vital for optimization of optical transmitters to be used in systems operating at 40 Gb/s and beyond, as standard measurement techniques will not suffice to optimize such high-speed systems
Vegetarianism
Ethical vegetarians maintain that vegetarianism is morally required. The principal reasons offered in support of ethical vegetarianism are: (i) concern for the welfare and well-being of the animals being eaten, (ii) concern for the environment, (iii) concern over global food scarcity and the just distribution of resources, and (iv) concern for future generations. Each of these reasons is explored in turn, starting with a historical look at ethical vegetarianism and the moral status of animals
Multiply Folded Graphene
The folding of paper, hide, and woven fabric has been used for millennia to
achieve enhanced articulation, curvature, and visual appeal for intrinsically
flat, two-dimensional materials. For graphene, an ideal two-dimensional
material, folding may transform it to complex shapes with new and distinct
properties. Here, we present experimental results that folded structures in
graphene, termed grafold, exist, and their formations can be controlled by
introducing anisotropic surface curvature during graphene synthesis or transfer
processes. Using pseudopotential-density functional theory calculations, we
also show that double folding modifies the electronic band structure of
graphene. Furthermore, we demonstrate the intercalation of C60 into the
grafolds. Intercalation or functionalization of the chemically reactive folds
further expands grafold's mechanical, chemical, optical, and electronic
diversity.Comment: 29 pages, 10 figures (accepted in Phys. Rev. B
Coexistence and critical behaviour in a lattice model of competing species
In the present paper we study a lattice model of two species competing for
the same resources. Monte Carlo simulations for d=1, 2, and 3 show that when
resources are easily available both species coexist. However, when the supply
of resources is on an intermediate level, the species with slower metabolism
becomes extinct. On the other hand, when resources are scarce it is the species
with faster metabolism that becomes extinct. The range of coexistence of the
two species increases with dimension. We suggest that our model might describe
some aspects of the competition between normal and tumor cells. With such an
interpretation, examples of tumor remission, recurrence and of different
morphologies are presented. In the d=1 and d=2 models, we analyse the nature of
phase transitions: they are either discontinuous or belong to the
directed-percolation universality class, and in some cases they have an active
subcritical phase. In the d=2 case, one of the transitions seems to be
characterized by critical exponents different than directed-percolation ones,
but this transition could be also weakly discontinuous. In the d=3 version,
Monte Carlo simulations are in a good agreement with the solution of the
mean-field approximation. This approximation predicts that oscillatory
behaviour occurs in the present model, but only for d>2. For d>=2, a steady
state depends on the initial configuration in some cases.Comment: 11 pages, 14 figure
Experimental determination of superconducting parameters for the intermetallic perovskite superconductor ${\text {MgCNi}}_3
We have measured upper-critical-field , specific heat C, and
tunneling spectra of the intermetallic perovskite superconductor MgCNi
with a superconducting transition temperature K. Based
on these measurements and relevant theoretical relations, we have evaluated
various superconducting parameters for this material, including the
thermodynamic critical field (0), coherence length (0),
penetration depth (0), lower-critical-field (0), and
Ginsberg-Landau parameter (0). From the specific heat, we obtain the
Debye temperature 280 K. We find a jump of
=2.3 at (where is the
normal state electronic specific coefficient), which is much larger than the
weak coupling BCS value of 1.43. Our tunneling measurements revealed a gap
feature in the tunneling spectra at with 4.6, again larger than the weak-coupling value
of 3.53. Both findings indicate that MgCNi is a strong-coupling
superconductor. In addition, we observed a pronounced zero-bias conductance
peak (ZBCP) in the tunneling spectra.
We discuss the possible physical origins of the observed ZBCP, especially in
the context of the pairing symmetry of the material.Comment: 5 pages, 4 figure
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