906 research outputs found
Hierarchical Character-Word Models for Language Identification
Social media messages' brevity and unconventional spelling pose a challenge
to language identification. We introduce a hierarchical model that learns
character and contextualized word-level representations for language
identification. Our method performs well against strong base- lines, and can
also reveal code-switching
Detection of per- and polyfluoroalkyl water contaminants with multiplexed 4D microcavities sensor
The per- and polyfluoroalkyl substances (PFAS) constitute a group of
organofluorine chemicals treated as the emerging pollutants and currently are
of particularly acute concern. These compounds have been employed intensively
as surfactants over multiple decades and are already to be found in surface and
ground waters at amounts sufficient to have an effect on the human health and
ecosystems. Because of the carbon-fluorine bonds the PFAS have an extreme
environmental persistence and their negative impact accumulates with further
production and penetration into the environment. In Germany alone, more than
thousands sites have been identified to be contaminated with PFAS and thus
timely detection of PFAS residues is becoming a high-priority task. In this
paper we report on the high performance optical detection method based on
whispering gallery modes microcavities applied for the first time for detection
of the PFAS contaminants in aqueous solutions. A self-sensing boosted 4D
microcavity fabricated with two-photon polymerization is employed as an
individual sensing unit. On example of the multiplexed imaging sensor with
multiple hundreds of simultaneously interrogated microcavities we demonstrate
the possibility to detect the PFAS chemicals representatives at the level of
down to 1 ppb
Perturbative Quantum Field Theory at Positive Temperatures: An Axiomatic Approach
It is shown that the perturbative expansions of the correlation functions of
a relativistic quantum field theory at finite temperature are uniquely
determined by the equations of motion and standard axiomatic requirements,
including the KMS condition. An explicit expression as a sum over generalized
Feynman graphs is derived. The canonical formalism is not used, and the
derivation proceeds from the beginning in the thermodynamic limit. No doubling
of fields is invoked. An unsolved problem concerning existence of these
perturbative expressions is pointed out.Comment: 17pages Late
Lehmann-Symanzik-Zimmermann S-Matrix elements on the Moyal Plane
Field theories on the Groenewold-Moyal(GM) plane are studied using the
Lehmann-Symanzik-Zimmermann(LSZ) formalism. The example of real scalar fields
is treated in detail. The S-matrix elements in this non-perturbative approach
are shown to be equal to the interaction representation S-matrix elements. This
is a new non-trivial result: in both cases, the S-operator is independent of
the noncommutative deformation parameter and the change in
scattering amplitudes due to noncommutativity is just a time delay. This result
is verified in two different ways. But the off-shell Green's functions do
depend on . In the course of this analysis, unitarity of the
non-perturbative S-matrix is proved as well.Comment: 18 pages, minor corrections, To appear in Phys. Rev. D, 201
Low-Density Granulocytes Are a Novel Immunopathological Feature in Both Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder
Objective: To investigate whether low-density granulocytes (LDGs) are an immunophenotypic feature of patients with multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD).
Methods: Blood samples were collected from 20 patients with NMOSD and 17 patients with MS, as well as from 15 patients with Systemic Lupus Erythematosus (SLE) and 23 Healthy Donors (HD). We isolated peripheral blood mononuclear cells (PBMCs) with density gradient separation and stained the cells with antibodies against CD14, CD15, CD16, and CD45, and analyzed the cells by flow cytometry or imaging flow cytometry. We defined LDGs as CD14-CD15(high) and calculated their share in total PBMC leukocytes (CD45+) as well as the share of CD16(hi) LDGs. Clinical data on disease course, medication, and antibody status were obtained.
Results: LDGs were significantly more common in MS and NMOSD than in HDs, comparable to SLE samples (median values HD 0.2%, MS 0.9%, NMOSD 2.1%, SLE 4.3%). 0/23 of the HDs, but 17/20 NMOSD and 11/17 MS samples as well as 13/15 SLE samples had at least 0.7 % LDGs. NMOSD patients without continuous immunosuppressive treatment had significantly more LDGs compared to their treated counterparts. LDG nuclear morphology ranged from segmented to rounded, suggesting a heterogeneity within the group.
Conclusion: LDGs are a feature of the immunophenotype in some patients with MS and NMOSD
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Development of electrically conductive microstructures based on polymer/CNT nanocomposites via two-photon polymerization
Femtosecond laser-induced two-photon polymerization (2PP) of carbon nanofiller doped polymers was utilized to produce electrically conductive microstructures, which are expected to be applicable as microelectronic components or micro-electromechanical systems in sensors. The nanocomposites were processed by compounding an inorganic-organic hybrid material with two different types (short and long) of single walled carbon nanotubes (SWCNTs). Different SWCNT contents were dispersed in the polymer by sonication to adjust the electrical conductivity of the nanocomposites. Low surface resistivity values of ~ 4.6 × 105 Ω/sq. could be measured for coated reference films with a thickness of 30 μm having an exceptionally low SWCNT content of 0.01 wt% of the long type of SWCNTs. In contrast, a higher minimum resistivity of 1.5 × 106 Ω/sq. was exhibited for composites with a higher content, 2 wt%, of short SWCNTs. The structural quality of the microstructures processed by 2PP was mainly influenced by the dispersion quality of the SWCNTs. To characterize the electrical conductivity, conductive atomic force microscopy was applied for the first time. In microstructures with 0.05 wt% of the long type of SWCNTs, a contact current could be detected over a wide range of the measured area visualizing the electrical conductive CNT network, which has not been reported before
Spontaneous Symmetry Breaking in Twisted Noncommutative Quantum Theories
We analyse aspects of symmetry breaking for Moyal spacetimes within a
quantisation scheme which preserves the twisted Poincar\'e symmetry. Towards
this purpose, we develop the LSZ approach for Moyal spacetimes. The latter
gives a formula for scattering amplitudes on these spacetimes which can be
obtained from the corresponding ones on the commutative spacetime. This formula
applies in the presence of spontaneous breakdown of symmetries as well.We also
derive Goldstone's theorem on Moyal spacetime. The formalism developed here can
be directly applied to the twisted standard model.Comment: +13 pages; minor changes in references,To appear in Phys Rev
Relative spatial differences in sediment transport in fire-affected agricultural landscapes: A field study
Available online 15 April 2019Fires can considerably increase wind erosion risk in dryland agricultural regions. While wind erosion post-fire has been extensively studied in rangeland and grazing landscapes, limited work has considered post-fire erosion on annual plant communities and annual crops. Here we evaluated the relative spatial differences in patterns of sediment transport between burnt and unburnt crop stubble sites. Following a severe wildfire, we studied the spatio-temporal pattern of aeolian sediment transport with an array of Modified Wilson and Cooke (MWAC) dust samplers on adjacent burnt and unburnt wheat stubble. Sediment collection was conducted during nine weeks over an area of 3 ha. Collection rates were converted to horizontal sediment flux to derive spatial distribution maps and perform statistical analysis. Compared to the unburnt plot, we observed that sediment transport was up to 1000 times higher within the burnt area. This could lead to damages to emerging annual crops sown after the fire if no management strategy was applied. There was only negligible sediment flux in areas with shallow and low-density stubble, which gradually increased with distance from the unburnt area. These results suggest that strips of remaining unburnt stubble could provide a potential benefit to adjacent burnt or bare plots. Patterns of sediment transport were consistent in all sampling periods and were observed at a spatial scale undetectable in wind tunnel studies, indicating that field observations could complement fine-scale experimental studies to assess environmental processes in real-life conditions.Amelie C. Jeanneau, Bertram Ostendorf, Tim Herrman
TIFA: Accurate and Interpretable Text-to-Image Faithfulness Evaluation with Question Answering
Despite thousands of researchers, engineers, and artists actively working on
improving text-to-image generation models, systems often fail to produce images
that accurately align with the text inputs. We introduce TIFA (Text-to-Image
Faithfulness evaluation with question Answering), an automatic evaluation
metric that measures the faithfulness of a generated image to its text input
via visual question answering (VQA). Specifically, given a text input, we
automatically generate several question-answer pairs using a language model. We
calculate image faithfulness by checking whether existing VQA models can answer
these questions using the generated image. TIFA is a reference-free metric that
allows for fine-grained and interpretable evaluations of generated images. TIFA
also has better correlations with human judgments than existing metrics. Based
on this approach, we introduce TIFA v1.0, a benchmark consisting of 4K diverse
text inputs and 25K questions across 12 categories (object, counting, etc.). We
present a comprehensive evaluation of existing text-to-image models using TIFA
v1.0 and highlight the limitations and challenges of current models. For
instance, we find that current text-to-image models, despite doing well on
color and material, still struggle in counting, spatial relations, and
composing multiple objects. We hope our benchmark will help carefully measure
the research progress in text-to-image synthesis and provide valuable insights
for further research
The interrelation between the electronic parameters of nitrogen atom and intramolecular interactions in ammonia derivatives
The electronic parameters and intramolecular interactions in the ground and transition states of inversion of the amines H₂NXHn (XHn=CH₃, NH₂, OH, F, SiH₃, PH₂, SH, Cl) were calculated using DFT (PBE96/def2-tzvpp) method. It was established that the electronacceptor properties of the XHn substituents has a prevailing influence on the change of the electronic parameters of nitrogen atom. Its increase leads to both a decrease of the charge on the nitrogen atom and an increase of the s-character and population of nitrogen lone pair (LP). All parameters under consideration correlate with the χ- and σᵢ-constants of the XHn substituents. The correlation coefficients increase when amines that contain X atoms only from one period are considered separately. It was found that the ρ values for amines containing X atoms from the second or third period are substantially different. The changes of the donor-acceptor interaction energies, s-character and LP population cannot be probable causes for different sensitivity of the electronic parameters of amines containing X atoms from different periods to the change of electron-acceptor properties of the XHn substituents. It was established that the mentioned parameters has only a subordinated influence in comparison with the influence of electron-acceptor ability of the XHn substituents. The negative charge on the nitrogen atom decreases with the increase of s-character and LP population and also with the decrease of energies of donor-acceptor interactions which lead to the withdrawal of electron density from the nitrogen atom. The s-character and LP population increase with the decrease of energies of donor-acceptor interactions which result in the reduction of electron density on the nitrogen atom. The total positive charges of the XHn groups and hydrogen atoms at the nitrogen atom decrease with increasing the electron-acceptor ability of the XHn substituents. The representation of the electron-acceptor properties of the substituents was shown to be more valid by using the χ-constants than by using the σᵢ-constants. The chlorine atom is a weak electron acceptor in comparison with an amino group
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