815 research outputs found
Gauge Theory, Geometry and the Large N Limit
We study the relationship between M theory on a nearly lightlike circle and
U(N) gauge theory in p+1 dimensions. We define large N limits of these theories
in which low energy supergravity is valid. The regularity of these limits
implies an infinite series of nonrenormalization theorems for the gauge theory
effective action, and the leading large N terms sum to a Born-Infeld form.
Compatibility of two different large N limits that describe the same
decompactified M theory leads to a conjecture for a relation between two limits
of string theories.Comment: LaTeX, 17 pages, 1 figure, references added, shorter version to
appear in Nucl. Phys.
RIXA - Explaining Artificial Intelligence in Natural Language
Natural language is the instinctive form of communication humans use among each other. Recently large language
models have drastically improved and made natural language
interfaces viable for all kinds of applications. We argue that
the use of natural language is a great tool to make explainable
artificial intelligence (XAI) accessible to end users. We present
our concept and work in progress implementation of a new kind
of XAI dashboard that uses a natural language chat. We specify 5
design goals for the dashboard and show the current state of our
implementation. The natural language chat is the main form of
interaction for our new dashboard. Through it the user should be
able to control all important aspects of our dashboard. We also
define success metrics we want to use to evaluate our work. Most
importantly we want to conduct user studies because we deem
them to be the best method of evaluation for end-user-centered
application
Evaluation of damping estimates by automated Operational Modal Analysis for offshore wind turbine tower vibrations
Unified Quantification of Quantum Defects in Small-Diameter Single-Walled Carbon Nanotubes by Raman Spectroscopy
The covalent functionalization of single-walled carbon nanotubes (SWCNTs)
with luminescent quantum defects enables their application as near-infrared
single-photon sources, as optical sensors, and for in-vivo tissue imaging.
Tuning the emission wavelength and defect density are crucial for these
applications. While the former can be controlled by different synthetic
protocols and is easily measured, defect densities are still determined as
relative rather than absolute values, limiting the comparability between
different nanotube batches and chiralities. Here, we present an absolute and
unified quantification metric for the defect density in SWCNT samples based on
Raman spectroscopy. It is applicable to a range of small-diameter nanotubes and
for arbitrary laser wavelengths. We observe a clear inverse correlation of the
D/G ratio increase with nanotube diameter, indicating that curvature
effects contribute significantly to the defect-activation of Raman modes.
Correlation of intermediate frequency modes with defect densities further
corroborates their activation by defects and provides additional quantitative
metrics for the characterization of functionalized SWCNTs
Heterotic Flux Attractors
We find attractor equations describing moduli stabilization for heterotic
compactifications with generic SU(3)-structure. Complex structure and K\"ahler
moduli are treated on equal footing by using SU(3)xSU(3)-structure at
intermediate steps. All independent vacuum data, including VEVs of the
stabilized moduli, is encoded in a pair of generating functions that depend on
fluxes alone. We work out an explicit example that illustrates our methods.Comment: 37 pages, references and clarifications adde
Multiple Instance Ensembling For Paranasal Anomaly Classification In The Maxillary Sinus
Paranasal anomalies are commonly discovered during routine radiological
screenings and can present with a wide range of morphological features. This
diversity can make it difficult for convolutional neural networks (CNNs) to
accurately classify these anomalies, especially when working with limited
datasets. Additionally, current approaches to paranasal anomaly classification
are constrained to identifying a single anomaly at a time. These challenges
necessitate the need for further research and development in this area.
In this study, we investigate the feasibility of using a 3D convolutional
neural network (CNN) to classify healthy maxillary sinuses (MS) and MS with
polyps or cysts. The task of accurately identifying the relevant MS volume
within larger head and neck Magnetic Resonance Imaging (MRI) scans can be
difficult, but we develop a straightforward strategy to tackle this challenge.
Our end-to-end solution includes the use of a novel sampling technique that not
only effectively localizes the relevant MS volume, but also increases the size
of the training dataset and improves classification results. Additionally, we
employ a multiple instance ensemble prediction method to further boost
classification performance. Finally, we identify the optimal size of MS volumes
to achieve the highest possible classification performance on our dataset.
With our multiple instance ensemble prediction strategy and sampling
strategy, our 3D CNNs achieve an F1 of 0.85 whereas without it, they achieve an
F1 of 0.70.
We demonstrate the feasibility of classifying anomalies in the MS. We propose
a data enlarging strategy alongside a novel ensembling strategy that proves to
be beneficial for paranasal anomaly classification in the MS
Unsupervised Anomaly Detection of Paranasal Anomalies in the Maxillary Sinus
Deep learning (DL) algorithms can be used to automate paranasal anomaly
detection from Magnetic Resonance Imaging (MRI). However, previous works relied
on supervised learning techniques to distinguish between normal and abnormal
samples. This method limits the type of anomalies that can be classified as the
anomalies need to be present in the training data. Further, many data points
from normal and anomaly class are needed for the model to achieve satisfactory
classification performance. However, experienced clinicians can segregate
between normal samples (healthy maxillary sinus) and anomalous samples
(anomalous maxillary sinus) after looking at a few normal samples. We mimic the
clinicians ability by learning the distribution of healthy maxillary sinuses
using a 3D convolutional auto-encoder (cAE) and its variant, a 3D variational
autoencoder (VAE) architecture and evaluate cAE and VAE for this task.
Concretely, we pose the paranasal anomaly detection as an unsupervised anomaly
detection problem. Thereby, we are able to reduce the labelling effort of the
clinicians as we only use healthy samples during training. Additionally, we can
classify any type of anomaly that differs from the training distribution. We
train our 3D cAE and VAE to learn a latent representation of healthy maxillary
sinus volumes using L1 reconstruction loss. During inference, we use the
reconstruction error to classify between normal and anomalous maxillary
sinuses. We extract sub-volumes from larger head and neck MRIs and analyse the
effect of different fields of view on the detection performance. Finally, we
report which anomalies are easiest and hardest to classify using our approach.
Our results demonstrate the feasibility of unsupervised detection of paranasal
anomalies from MRIs with an AUPRC of 85% and 80% for cAE and VAE, respectively
Emotional Faces in Symbolic Relations: A Happiness Superiority Effect Involving the Equivalence Paradigm
Conformal Symmetry for General Black Holes
We show that the warp factor of a generic asymptotically flat black hole in
five dimensions can be adjusted such that a conformal symmetry emerges. The
construction preserves all near horizon properties of the black holes, such as
the thermodynamic potentials and the entropy. We interpret the geometry with
modified asymptotic behavior as the "bare" black hole, with the ambient flat
space removed. Our warp factor subtraction generalizes hidden conformal
symmetry and applies whether or not rotation is significant. We also find a
relation to standard AdS/CFT correspondence by embedding the black holes in six
dimensions. The asymptotic conformal symmetry guarantees a dual CFT description
of the general rotating black holes.Comment: 26 page
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