3,429 research outputs found
BPS States of Exceptional Non-Critical Strings
We study the BPS states of non-critical strings which arise for zero size
instantons of exceptional groups. This is accomplished by using F-theory and
M-theory duals and by employing mirror symmetry to compute the degeneracy of
membranes wrapped around 2-cycles of the Calabi-Yau threefold. We find evidence
for a number of novel physical phenomena, including having infinitely many
light states with the first lightest state including a nearly massless
gravitino.Comment: 29 pages, 1 figure, references added, to appear in the proceedings of
the conference "Advanced Quantum Field Theory'' (in memory of Claude
Itzykson
Making a drama out of a crisis?:A multidisciplinary study of news media coverage of public health crises and the role of emotion
Das, H.H.J. [Promotor]Hartmann, T. [Copromotor
Information feedback and mass media effects in cultural dynamics
We study the effects of different forms of information feedback associated
with mass media on an agent-agent based model of the dynamics of cultural
dissemination. In addition to some processes previously considered, we also
examine a model of local mass media influence in cultural dynamics. Two
mechanisms of information feedback are investigated: (i) direct mass media
influence, where local or global mass media act as an additional element in the
network of interactions of each agent, and (ii) indirect mass media influence,
where global media acts as a filter of the influence of the existing network of
interactions of each agent. Our results generalize previous findings showing
that cultural diversity builds-up by increasing the strength of the mass media
influence. We find that this occurs independently of the mechanisms of action
(direct or indirect) of the mass media message. However, through an analysis of
the full range of parameters measuring cultural diversity, we establish that
the enhancement of cultural diversity produced by interaction with mass media
only occurs for strong enough mass media messages. In comparison with previous
studies a main different result is that weak mass media messages, in
combination with agent-agent interaction, are efficient in producing cultural
homogeneity. Moreover, the homogenizing effect of weak mass media messages are
more efficient for direct local mass media messages than for global mass media
messages or indirect global mass media influences.Comment: 20n pages, 10 figure
Discriminating spin through quantum interference
Many of the proposed solutions to the hierarchy and naturalness problems
postulate new `partner' fields to the standard model particles. Determining the
spins of these new particles will be critical in distinguishing among the
various possible SM extensions, yet proposed methods rely on the underlying
models. We propose a new model-independent method for spin measurements which
takes advantage of quantum interference among helicity states. We demonstrate
that this method will be able to discriminate scalar particles from higher spin
states at the ILC, and discuss application to higher spins and possible uses at
the LHC.Comment: 11 pages, 11 figure
Possible indicators for low dimensional superconductivity in the quasi-1D carbide Sc3CoC4
The transition metal carbide Sc3CoC4 consists of a quasi-one-dimensional (1D)
structure with [CoC4]_{\inft} polyanionic chains embedded in a scandium
matrix. At ambient temperatures Sc3CoC4 displays metallic behavior. At lower
temperatures, however, charge density wave formation has been observed around
143K which is followed by a structural phase transition at 72K. Below T^onset_c
= 4.5K the polycrystalline sample becomes superconductive. From Hc1(0) and
Hc2(0) values we could estimate the London penetration depth ({\lambda}_L ~=
9750 Angstroem) and the Ginsburg-Landau (GL) coherence length ({\xi}_GL ~= 187
Angstroem). The resulting GL-parameter ({\kappa} ~= 52) classifies Sc3CoC4 as a
type II superconductor. Here we compare the puzzling superconducting features
of Sc3CoC4, such as the unusual temperature dependence i) of the specific heat
anomaly and ii) of the upper critical field H_c2(T) at T_c, and iii) the
magnetic hysteresis curve, with various related low dimensional
superconductors: e.g., the quasi-1D superconductor (SN)_x or the 2D
transition-metal dichalcogenides. Our results identify Sc3CoC4 as a new
candidate for a quasi-1D superconductor.Comment: 4 pages, 5 figure
ScreenGarden: a shinyR application for fast and easy analysis of plate-based high-throughput screens
BACKGROUND: Colony growth on solid media is a simple and effective measure for high-throughput genomic experiments such as yeast two-hybrid, synthetic dosage lethality and Synthetic Physical Interaction screens. The development of robotic pinning tools has facilitated the experimental design of these assays, and different imaging software can be used to automatically measure colony sizes on plates. However, comparison to control plates and statistical data analysis is often laborious and pinning issues or plate specific growth effects can lead to the detection of false-positive growth defects. RESULTS: We have developed ScreenGarden, a shinyR application, to enable easy, quick and robust data analysis of plate-based high throughput assays. The code allows comparisons of different formats of data and different sized arrays of colonies. A comparison of ScreenGarden with previous analysis tools shows that it performs, at least, equivalently. The software can be run either via a website or offline via the RStudio program; the code is available and can be modified by expert uses to customise the analysis. CONCLUSIONS: ScreenGarden provides a simple, fast and effective tool to analyse colony growth data from genomic experiments. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12859-022-04586-1
Topological Strings and (Almost) Modular Forms
The B-model topological string theory on a Calabi-Yau threefold X has a
symmetry group Gamma, generated by monodromies of the periods of X. This acts
on the topological string wave function in a natural way, governed by the
quantum mechanics of the phase space H^3(X). We show that, depending on the
choice of polarization, the genus g topological string amplitude is either a
holomorphic quasi-modular form or an almost holomorphic modular form of weight
0 under Gamma. Moreover, at each genus, certain combinations of genus g
amplitudes are both modular and holomorphic. We illustrate this for the local
Calabi-Yau manifolds giving rise to Seiberg-Witten gauge theories in four
dimensions and local P_2 and P_1 x P_1. As a byproduct, we also obtain a simple
way of relating the topological string amplitudes near different points in the
moduli space, which we use to give predictions for Gromov-Witten invariants of
the orbifold C^3/Z_3.Comment: 62 pages, 1 figure; v2: minor correction
Heat capacity of the quantum magnet TiOCl
Measurements of the heat capacity C(T,H) of the one-dimensional quantum
magnet TiOCl are presented for temperatures 2K < T < 300K and magnetic fields
up to 5T. Distinct anomalies at 91K and 67K signal two subsequent phase
transitions. The lower of these transitions clearly is of first order and seems
to be related to the spin degrees of freedom. The transition at 92K probably
involves the lattice and/or orbital moments. A detailed analysis of the data
reveals that the entropy change through both transitions is surprisingly small
(~ 0.1R), pointing to the existence strong fluctuations well into the
non-ordered high-temperature phase. No significant magnetic field dependence
was detected.Comment: 4 pages, 2 figure
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