20,011 research outputs found
Crosslingual Document Embedding as Reduced-Rank Ridge Regression
There has recently been much interest in extending vector-based word
representations to multiple languages, such that words can be compared across
languages. In this paper, we shift the focus from words to documents and
introduce a method for embedding documents written in any language into a
single, language-independent vector space. For training, our approach leverages
a multilingual corpus where the same concept is covered in multiple languages
(but not necessarily via exact translations), such as Wikipedia. Our method,
Cr5 (Crosslingual reduced-rank ridge regression), starts by training a
ridge-regression-based classifier that uses language-specific bag-of-word
features in order to predict the concept that a given document is about. We
show that, when constraining the learned weight matrix to be of low rank, it
can be factored to obtain the desired mappings from language-specific
bags-of-words to language-independent embeddings. As opposed to most prior
methods, which use pretrained monolingual word vectors, postprocess them to
make them crosslingual, and finally average word vectors to obtain document
vectors, Cr5 is trained end-to-end and is thus natively crosslingual as well as
document-level. Moreover, since our algorithm uses the singular value
decomposition as its core operation, it is highly scalable. Experiments show
that our method achieves state-of-the-art performance on a crosslingual
document retrieval task. Finally, although not trained for embedding sentences
and words, it also achieves competitive performance on crosslingual sentence
and word retrieval tasks.Comment: In The Twelfth ACM International Conference on Web Search and Data
Mining (WSDM '19
Update of MRST parton distributions.
We discuss the latest update of the MRST parton distributions in response
to the most recent data. We discuss the areas where there are hints
of difficulties in the global fit, and compare to some other updated sets of
parton distributions, particularly CTEQ6. We briefly discuss the issue of
uncertainties associated with partons
MRST global fit update.
We discuss the impact of the most recent data on the MRST global analysis -
in particular the new high-ET jet data and their implications for the gluon and
the new small x structure function data. In the light of these new data we also
consider the uncertainty in predictions for physical quantities depending on parton
distributions, concentrating on the W cross-section at hadron colliders
Subglacial drainage processes at a High Arctic polythermal valley glacier
Peer reviewedPublisher PD
Updates of PDFs for the 2nd LHC run
I present results on continuing updates in PDFs within the framework now
called MMHT14 due to both theory improvements and the inclusion of new data
sets, including most of the up-to-date LHC data. A new set of PDFs is
essentially finalised, with no changes expected to the PDFs presented here.Comment: 6 pages, 5 figures. Proceedings of the 37th International Conference
of High-Energy Physics (ICHEP2014), 2-9 July 2014, Valencia, Spai
InGaN epilayer characterization by microfocused x-ray reciprocal space mapping
We report the use of microfocused three-dimensional x-ray reciprocal space mapping to study InGaN epilayers with average InN content 20%-22%. Analysis of the full volume of reciprocal space, while probing samples on the microscale with a focused x-ray beam, allowed us to gain valuable information about the nanostructure of InN-rich InGaN epilayers. It is found that âseedâ InGaN mosaic nanocrystallites are twisted with respect to the ensemble average and strain-free. The initial stages of InGaN-on-GaN epitaxial growth, therefore, conform to the Volmer-Weber growth mechanism with âseedsâ nucleated on strain fields generated by the a-type edge dislocations
Explicit Calculation Of the Running Coupling BFKL Anomalous Dimension
I calculate the anomalous dimension governing the Q^2 evolution of the gluon
(and structure functions) coming from the running coupling BFKL equation. This
may be expressed in an exact analytic form, up to a small ultraviolet
renormalon contribution, and hence the corresponding splitting function may be
determined precisely. Rather surprisingly it is most efficient to expand the
gluon distribution in powers of alpha_s(Q^2) rather than use the traditional
expansion where all orders of alpha_s\ln(1/x) are kept on an equal footing. The
anomalous dimension is very different from that obtained from the fixed
coupling equation, and leads to a powerlike behaviour for the splitting
function as x ->0 which is far weaker, i.e. about x^(-0.2). The NLO corrections
to the anomalous dimension are rather small, unlike the fixed coupling case,
and a stable perturbative expansion is obtained.Comment: Tex file, including a modification of Harvmac, 15 pages, 5 figures as
.ps file
Sub-Poissonian statistics of Rydberg-interacting dark-state polaritons
Interfacing light and matter at the quantum level is at the heart of modern
atomic and optical physics and enables new quantum technologies involving the
manipulation of single photons and atoms. A prototypical atom-light interface
is electromagnetically induced transparency, in which quantum interference
gives rise to hybrid states of photons and atoms called dark-state polaritons.
We have observed individual dark-state polaritons as they propagate through an
ultracold atomic gas involving Rydberg states. Strong long-range interactions
between Rydberg atoms give rise to an effective interaction blockade for
dark-state polaritons, which results in large optical nonlinearities and
modified polariton number statistics. The observed statistical fluctuations
drop well below the quantum noise limit indicating that photon correlations
modified by the strong interactions have a significant back-action on the
Rydberg atom statistics.Comment: 7 pages, 4 figure
Optimal guidance law development for an advanced launch system
The proposed investigation on a Matched Asymptotic Expansion (MAE) method was carried out. It was concluded that the method of MAE is not applicable to launch vehicle ascent trajectory optimization due to a lack of a suitable stretched variable. More work was done on the earlier regular perturbation approach using a piecewise analytic zeroth order solution to generate a more accurate approximation. In the meantime, a singular perturbation approach using manifold theory is also under current investigation. Work on a general computational environment based on the use of MACSYMA and the weak Hamiltonian finite element method continued during this period. This methodology is capable of the solution of a large class of optimal control problems
Predicting the outcomes of treatment to eradicate the latent reservoir for HIV-1
Massive research efforts are now underway to develop a cure for HIV
infection, allowing patients to discontinue lifelong combination antiretroviral
therapy (ART). New latency-reversing agents (LRAs) may be able to purge the
persistent reservoir of latent virus in resting memory CD4+ T cells, but the
degree of reservoir reduction needed for cure remains unknown. Here we use a
stochastic model of infection dynamics to estimate the efficacy of LRA needed
to prevent viral rebound after ART interruption. We incorporate clinical data
to estimate population-level parameter distributions and outcomes. Our findings
suggest that approximately 2,000-fold reductions are required to permit a
majority of patients to interrupt ART for one year without rebound and that
rebound may occur suddenly after multiple years. Greater than 10,000-fold
reductions may be required to prevent rebound altogether. Our results predict
large variation in rebound times following LRA therapy, which will complicate
clinical management. This model provides benchmarks for moving LRAs from the
lab to the clinic and can aid in the design and interpretation of clinical
trials. These results also apply to other interventions to reduce the latent
reservoir and can explain the observed return of viremia after months of
apparent cure in recent bone marrow transplant recipients and an
immediately-treated neonate.Comment: 8 pages main text (4 figures). In PNAS Early Edition
http://www.pnas.org/content/early/2014/08/05/1406663111. Ancillary files: SI,
24 pages SI (7 figures). File .htm opens a browser-based application to
calculate rebound times (see SI). Or, the .cdf file can be run with
Mathematica. The most up-to-date version of the code is available at
http://www.danielrosenbloom.com/reboundtimes
- âŠ