22,636 research outputs found
Personalized Pancreatic Tumor Growth Prediction via Group Learning
Tumor growth prediction, a highly challenging task, has long been viewed as a
mathematical modeling problem, where the tumor growth pattern is personalized
based on imaging and clinical data of a target patient. Though mathematical
models yield promising results, their prediction accuracy may be limited by the
absence of population trend data and personalized clinical characteristics. In
this paper, we propose a statistical group learning approach to predict the
tumor growth pattern that incorporates both the population trend and
personalized data, in order to discover high-level features from multimodal
imaging data. A deep convolutional neural network approach is developed to
model the voxel-wise spatio-temporal tumor progression. The deep features are
combined with the time intervals and the clinical factors to feed a process of
feature selection. Our predictive model is pretrained on a group data set and
personalized on the target patient data to estimate the future spatio-temporal
progression of the patient's tumor. Multimodal imaging data at multiple time
points are used in the learning, personalization and inference stages. Our
method achieves a Dice coefficient of 86.8% +- 3.6% and RVD of 7.9% +- 5.4% on
a pancreatic tumor data set, outperforming the DSC of 84.4% +- 4.0% and RVD
13.9% +- 9.8% obtained by a previous state-of-the-art model-based method
Contact interactions in low scale string models with intersecting -branes
We evaluate the tree level four fermion string amplitudes in the TeV string
mass scale models with intersecting -branes. The coefficient functions of
contact interactions subsuming the contributions of string Regge resonance and
winding mode excitations are obtained by subtracting out the contributions from
the string massless and massive momentum modes. Numerical applications are
developed for the Standard Model like solution of Cremades, Ibanez, and
Marchesano for a toroidal orientifold with four intersecting -brane stacks.
The chirality conserving contact interactions of the quarks and leptons are
considered in applications to high energy collider and flavor changing neutral
current phenomenology. The two main free parameters consist of the string and
compactification mass scales, and . Useful constraints on these
parameters are derived from predictions for the Bhabha scattering differential
cross section and for the observables associated to the mass shifts of the
neutral meson systems and the lepton number
violating three-body leptonic decays of the charged leptons and .Comment: 34 pages, 7 figure
Properties of the phi meson at high temperatures and densities
We calculate the spectral density of the phi meson in a hot bath of nucleons
and pions using a general formalism relating self-energy to the forward
scattering amplitude (FSA). In order to describe the low energy FSA, we use
experimental data along with a background term. For the high energy FSA, a
Regge parameterization is employed. We verify the resulting FSA using
dispersion techniques. We find that the position of the peak of the spectral
density is slightly shifted from its vacuum position and that its width is
considerably increased. The width of the spectral density at a temperature of
150 MeV and at normal nuclear density is more than 90 MeV.Comment: 4 pages, 5 figures, Poster presented at Quark Matter 200
Single-qubit optical quantum fingerprinting
We analyze and demonstrate the feasibility and superiority of linear optical
single-qubit fingerprinting over its classical counterpart. For one-qubit
fingerprinting of two-bit messages, we prepare `tetrahedral' qubit states
experimentally and show that they meet the requirements for quantum
fingerprinting to exceed the classical capability. We prove that shared
entanglement permits 100% reliable quantum fingerprinting, which will
outperform classical fingerprinting even with arbitrary amounts of shared
randomness.Comment: 4 pages, one figur
Phase diagram and excitations of a Shiba molecule
We analyze the phase diagram associated with a pair of magnetic impurities
trapped in a superconducting host. The natural interplay between Kondo
screening, superconductivity and exchange interactions leads to a rich array of
competing phases, whose transitions are characterized by discontinuous changes
of the total spin. Our analysis is based on a combination of numerical
renormalization group techniques as well as semi-classical analytics. In
addition to the expected screened and unscreened phases, we observe a new
molecular doublet phase where the impurity spins are only partially screened by
a single extended quasiparticle. Direct signatures of the various Shiba
molecule states can be observed via RF spectroscopy.Comment: 13 pages, 7 figure
Seasonal distribution and drivers of surface fine particulate matter and organic aerosol over the Indo-Gangetic Plain
The Indo-Gangetic Plain (IGP) is home to 9 % of the global population and is responsible for a
large fraction of agricultural crop production in Pakistan, India, and Bangladesh. Levels of fine particulate matter (mean diameter <2.5 µm, PM2.5)
across the IGP often exceed human health recommendations, making
cities across the IGP among the most polluted in the world. Seasonal
changes in the physical environment over the IGP are dominated by the
large-scale south Asian monsoon system that dictates the timing of
agricultural planting and harvesting. We use the WRF-Chem model to study the seasonal anthropogenic,
pyrogenic, and biogenic influences on fine particulate matter and its
constituent organic aerosol (OA) over the IGP
that straddles Pakistan, India, and Bangladesh during 2017–2018. We find that surface air quality
during pre-monsoon (March–May) and monsoon (June–September) seasons is
better than during post-monsoon (October–December) and winter
(January–February) seasons, but all seasonal mean values of PM2.5
still exceed the recommended levels, so that air pollution is a year-round problem. Anthropogenic
emissions influence the magnitude and distribution of PM2.5 and
OA throughout the year, especially over urban sites, while pyrogenic
emissions result in localised contributions over the central and upper
parts of IGP in all non-monsoonal seasons, with the highest impact during
post-monsoon seasons that correspond to the post-harvest season in the
agricultural calendar. Biogenic emissions play an important role in
the magnitude and distribution of PM2.5 and OA during the monsoon
season, and they show a substantial contribution to secondary OA (SOA),
particularly over the lower IGP. We find that the OA contribution to
PM2.5 is significant in all four seasons (17 %–30 %), with primary
OA generally representing the larger fractional contribution. We find
that the volatility distribution of SOA is driven mainly by the mean
total OA loading and the washout of aerosols and gas-phase aerosol
precursors that result in SOA being less volatile during the
pre-monsoon and monsoon season than during the post-monsoon and winter
seasons.</p
Lower bounds in the quantum cell probe model
We introduce a new model for studying quantum data structure problems --- the "quantum cell probe model". We prove a lower bound for the static predecessor problem in the 'address-only' version of this model where, essentially, we allow quantum parallelism only over the 'address lines' of the queries. This model subsumes the classical cell probe model, and many quantum query algorithms like Grover's algorithm fall into this framework. We prove our lower bound by obtaining a round elimination lemma for quantum communication complexity. A similar lemma was proved by Miltersen, Nisan, Safra and Wigderson for classical communication complexity, but their proof does not generalise to the quantum setting. We also study the static membership problem in the quantum cell probe model. Generalising a result of Yao, we show that if the storage scheme is 'implicit', that is it can only store members of the subset and 'pointers', then any quantum query scheme must make \Omega(\log n) probes. We also consider the one-round quantum communication complexity of set membership and show tight bounds
Possibility, Impossibility and Cheat-Sensitivity of Quantum Bit String Commitment
Unconditionally secure non-relativistic bit commitment is known to be
impossible in both the classical and the quantum worlds. But when committing to
a string of n bits at once, how far can we stretch the quantum limits? In this
paper, we introduce a framework for quantum schemes where Alice commits a
string of n bits to Bob in such a way that she can only cheat on a bits and Bob
can learn at most b bits of information before the reveal phase. Our results
are two-fold: we show by an explicit construction that in the traditional
approach, where the reveal and guess probabilities form the security criteria,
no good schemes can exist: a+b is at least n. If, however, we use a more
liberal criterion of security, the accessible information, we construct schemes
where a=4log n+O(1) and b=4, which is impossible classically. We furthermore
present a cheat-sensitive quantum bit string commitment protocol for which we
give an explicit tradeoff between Bob's ability to gain information about the
committed string, and the probability of him being detected cheating.Comment: 10 pages, RevTex, 2 figure. v2: title change, cheat-sensitivity adde
Quantum fingerprinting
Classical fingerprinting associates with each string a shorter string (its
fingerprint), such that, with high probability, any two distinct strings can be
distinguished by comparing their fingerprints alone. The fingerprints can be
exponentially smaller than the original strings if the parties preparing the
fingerprints share a random key, but not if they only have access to
uncorrelated random sources. In this paper we show that fingerprints consisting
of quantum information can be made exponentially smaller than the original
strings without any correlations or entanglement between the parties: we give a
scheme where the quantum fingerprints are exponentially shorter than the
original strings and we give a test that distinguishes any two unknown quantum
fingerprints with high probability. Our scheme implies an exponential
quantum/classical gap for the equality problem in the simultaneous message
passing model of communication complexity. We optimize several aspects of our
scheme.Comment: 8 pages, LaTeX, one figur
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