17,050 research outputs found
Nonlinearity in Bacterial Population Dynamics: Proposal for Experiments for the Observation of Abrupt Transitions in Patches
An explicit proposal for experiments leading to abrupt transitions in
spatially extended bacterial populations in a Petri dish is presented on the
basis of an exact formula obtained through an analytic theory. The theory
provides accurately the transition expressions in spite of the fact that the
actual solutions, which involve strong nonlinearity, are inaccessible to it.
The analytic expressions are verified through numerical solutions of the
relevant nonlinear equation. The experimental set-up suggested uses opaque
masks in a Petri dish bathed in ultraviolet radiation as in Lin et al.,
Biophys. J. {\bf 87}, 75 (2004) and Perry, J. R. Soc. Interface {\bf 2}, 379
(2005) but is based on the interplay of two distances the bacteria must
traverse, one of them favorable and the other adverse. As a result of this
interplay feature, the experiments proposed introduce highly enhanced
reliability in interpretation of observations and in the potential for
extraction of system parameters.Comment: 5 figure
Thermal rectifier from deformed carbon nanohorns
We study thermal rectification in single-walled carbon nanohorns (SWNHs) by
using non-equilibrium molecular dynamics (MD) method. It is found that the
horns with the bigger top angles show larger asymmetric heat transport due to
the larger structural gradient distribution. This kind of gradient behavior can
be further adjusted by applying external strain on the SWNHs. After being
carefully elongated along the axial direction, the thermal rectification in the
elongated SWNHs can become more obvious than that in undeformed ones. The
maximum rectification efficiency of SWNHs is much bigger than that of carbon
nanotube intramolecular junctions.Comment: 3 figure
Blasphemy: A Romantic Comic about the Devil Himself
The tendency for societies to organize themselves around contours of sameness and difference leads naturally to social constructions of us versus them. Individuals are primed to identify with the groups to which they belong, and thus intellectually classify those unlike themselves as the other. Our social inclination toward othering is intractable and ubiquitous across cultures. It breeds conditions of chronic inequality and marginality, reinforcing the ethos of xenophobia that perpetuates and undergirds human atrocities such as war, slavery, and genocide. Through a creative project — a webcomic entitled Blasphemy — I address and illustrate how othering behavior can manifest in the world. Armed with the knowledge that powerful lessons can be gleaned from the arts, the goal is to raise awareness of othering and its deleterious impacts on individuals, and the wider society. Blasphemy co-mingles narrative and visual image in a long-form, serialized webcomic leveraging my study of art and psychology and engaging my own yearning to lessen the suffering of those who find themselves marginalized or targets of discrimination. As is common practice in webcomic production, each update will advance the story until the full story arc reaches its satisfying conclusion. Given the length and nature of Blasphemy as a complete narrative published in series, the full execution of the project logically spans beyond the time scope of this thesis
Self-assembling DNA-caged particles: nanoblocks for hierarchical self-assembly
DNA is an ideal candidate to organize matter on the nanoscale, primarily due
to the specificity and complexity of DNA based interactions. Recent advances in
this direction include the self-assembly of colloidal crystals using DNA
grafted particles. In this article we theoretically study the self-assembly of
DNA-caged particles. These nanoblocks combine DNA grafted particles with more
complicated purely DNA based constructs. Geometrically the nanoblock is a
sphere (DNA grafted particle) inscribed inside a polyhedron (DNA cage). The
faces of the DNA cage are open, and the edges are made from double stranded
DNA. The cage vertices are modified DNA junctions. We calculate the
equilibriuim yield of self-assembled, tetrahedrally caged particles, and
discuss their stability with respect to alternative structures. The
experimental feasability of the method is discussed. To conclude we indicate
the usefulness of DNA-caged particles as nanoblocks in a hierarchical
self-assembly strategy.Comment: v2: 21 pages, 8 figures; revised discussion in Sec. 2, replaced 2
figures, added new reference
Enhancement of prompt photons in ultrarelativistic proton-proton collisions from nonlinear gluon evolution at small-
In this paper we estimate the influence of nonlinear gluon evolution in the
production of prompt photons at the LHC pp collider. We assume the validity of
collinear factorization and consider the EHKQS parton distributions, which are
solutions of the GLR-MQ evolution equations and describe quite well the DESY
HERA data, as input in our calculations. We find that both single and
double photon production are enhanced for low- photons and central
rapidities, while this effect is absent for the high- photons. The
implications of this effect for the Quark-Gluon Plasma searches and for the QCD
background to Higgs are also discussed.Comment: 4 pages, 4 figures. Version to be published in Physical Review
High resolution Ge/Li/ spectrometer reduces rate-dependent distortions at high counting rates
Modified spectrometer system with a low-noise preamplifier reduces rate-dependent distortions at high counting rates, 25,000 counts per second. Pole-zero cancellation minimizes pulse undershoots due to multiple time constants, baseline restoration improves resolution and prevents spectral shifts
Radio-frequency operation of a double-island single-electron transistor
We present results on a double-island single-electron transistor (DISET)
operated at radio-frequency (rf) for fast and highly sensitive detection of
charge motion in the solid state. Using an intuitive definition for the charge
sensitivity, we compare a DISET to a conventional single-electron transistor
(SET). We find that a DISET can be more sensitive than a SET for identical,
minimum device resistances in the Coulomb blockade regime. This is of
particular importance for rf operation where ideal impedance matching to 50 Ohm
transmission lines is only possible for a limited range of device resistances.
We report a charge sensitivity of 5.6E-6 e/sqrt(Hz) for a rf-DISET, together
with a demonstration of single-shot detection of small (<=0.1e) charge signals
on microsecond timescales.Comment: 6 pages, 6 figure
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Minimal Energy Clusters of Hard Spheres with Short Range Attractions
We calculate the ground states of hard-sphere clusters, in which n identical hard spherical particles bind by isotropic short-ranged attraction. Combining graph theoretic enumeration with basic geometry, we analytically solve for clusters of n9 the degeneracy decreases due to the formation of structures with >3n-6 contacts. Interestingly, for n=10 and possibly at n=11 and n=12, the ground states of this system are subsets of hexagonal close-packed crystals. The ground states are not icosahedra at n=12 and n=13. We relate our results to the structure and thermodynamics of suspensions of colloidal particles with short-ranged attractions.Engineering and Applied SciencesMolecular and Cellular BiologyPhysic
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