131 research outputs found
Graph Meets LLM: A Novel Approach to Collaborative Filtering for Robust Conversational Understanding
Conversational AI systems such as Alexa need to understand defective queries
to ensure robust conversational understanding and reduce user friction. These
defective queries often arise from user ambiguities, mistakes, or errors in
automatic speech recognition (ASR) and natural language understanding (NLU).
Personalized query rewriting is an approach that focuses on reducing defects
in queries by taking into account the user's individual behavior and
preferences. It typically relies on an index of past successful user
interactions with the conversational AI. However, unseen interactions within
the user's history present additional challenges for personalized query
rewriting. This paper presents our "Collaborative Query Rewriting" approach,
which specifically addresses the task of rewriting new user interactions that
have not been previously observed in the user's history. This approach builds a
"User Feedback Interaction Graph" (FIG) of historical user-entity interactions
and leverages multi-hop graph traversal to enrich each user's index to cover
future unseen defective queries. The enriched user index is called a
Collaborative User Index and contains hundreds of additional entries. To
counteract precision degradation from the enlarged index, we add additional
transformer layers to the L1 retrieval model and incorporate graph-based and
guardrail features into the L2 ranking model.
Since the user index can be pre-computed, we further investigate the
utilization of a Large Language Model (LLM) to enhance the FIG for user-entity
link prediction in the Video/Music domains. Specifically, this paper
investigates the Dolly-V2 7B model. We found that the user index augmented by
the fine-tuned Dolly-V2 generation significantly enhanced the coverage of
future unseen user interactions, thereby boosting QR performance on unseen
queries compared with the graph traversal only approach
Evaporative Enrichment of Oxygen-18 and Deuterium in Lake Waters on the Tibetan Plateau
Stable isotopes (δ18O and δD) are useful tracers for investigating hydrologic and climatic variability on a variety of temporal and spatial scales. Since the early isotopic studies on mountainous glaciers in the late 1960s, a great deal of information has been generated on the isotopic composition of rainfall, snow, ice, surface waters, and lake carbonate sediments across the Tibetan Plateau. However, measurements of δ18O and δD values of lake water are scarce. Here we present a new dataset of δ18O and δD values of lake waters collected from 27 lakes across the plateau during a reconnaissance survey in summer 2009. δ18O and δD values of lake water range from â19.9 to 6.6â° and from â153 to â16â°, respectively. The average values of δ18O and δD are â6.4 and â72â°, considerably greater than those of precipitation observed in this region. The derived Tibetan lake water line, δD = 5.2δ18O â 38.9, is significantly different from the global meteoric water line. Most of the lakes, including some freshwater lakes, contain water with negative values of d-excess (d). There is a negative correlation between d and total dissolved solids (TDS). Each of these findings indicates that evaporation-induced isotopic enrichment prevails in Tibetan lakes. Moreover, we develop an isotope modeling scheme to calculate E/P ratios for Tibetan lakes, using a combination of existing isotopic fractionation equations and the Rayleigh distillation model. We use the intersection of the local evaporation line and GMWL as a first approximation of δ18O and δD values of lake water inputs to infer an E/P ratio for each lake. Our modeling calculations reveal that although variable from lake to lake, the water budget across the plateau is positive, with an average E/P of 0.52. This is in good agreement with other observational and model data that show varying degrees of increases in lake size from satellite imagery and significant decreases in lake salinity in many lakes on the plateau over the last several decades. Together with the new isotopic dataset, the proposed modeling framework can be used to examine and quantify past changes in a lakeâs hydrologic balance from the isotopic record of downcore carbonate sediments in the region
Fabrication of porous metal by selective laser melting as catalyst support for hydrogen production microreactor
Abstract(#br)To improve the hydrogen production performance of microreactors, the selective laser melting method was proposed to fabricate the porous metals as catalyst supports with different pore structures, porosities, and materials. The influence of the porous structures on the molecule distribution after passing through the porous metals was analyzed by molecular dynamics simulation. The developed porous metals were then used as catalyst supports in a methanol steam reforming microreactor for hydrogen production. Our results show that the porosity of the porous metal had significantly influence on the catalyst infiltration and the reaction process of hydrogen production. A lower degree of catalyst infiltration of the porous metal was obtained with lower porosity. A copper layer-coated stainless-steel porous metal with a staggered structure and gradient porosity of 80%â60% exhibited much larger methanol conversion and H 2 flow rate due to its better heat and mass transfer characteristic. Methanol conversion and H 2 flow rates could reach 97% and 0.62 mol/h, respectively. Finally, it was found that the experimental results were in good agreement with the simulation results
GolgiP: prediction of Golgi-resident proteins in plants
Summary: We present a novel Golgi-prediction server, GolgiP, for computational prediction of both membrane- and non-membrane-associated Golgi-resident proteins in plants. We have employed a support vector machine-based classification method for the prediction of such Golgi proteins, based on three types of information, dipeptide composition, transmembrane domain(s) (TMDs) and functional domain(s) of a protein, where the functional domain information is generated through searching against the Conserved Domains Database, and the TMD information includes the number of TMDs, the length of TMD and the number of TMDs at the N-terminus of a protein. Using GolgiP, we have made genome-scale predictions of Golgi-resident proteins in 18 plant genomes, and have made the preliminary analysis of the predicted data
Galactic structure studies with BATC star counts
We report the first results of star counts carried out with the National
Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15
intermediate-band filters from 3000 to 10000 {\AA} in the BATC survey. We
analyze a sample of over 1400 main sequence stars (V), which lie
in the field with central coordinates R.A.= and
DEC=47 (J2000). The field of view is 0.95
deg, and the spatial scale was 1\arcsec.67. In our model, the
distribution of stars perpendicular to the plane of the Galaxy is given by two
exponential disks (thin disk plus thick disk) and a de Vaucouleurs halo. Based
on star counts, we derive the scale heights of the thin disk to be
pc and of the thick disk to be pc,
respectively, with a local density of of the thin disk. We find that
the observed counts support an axial ratio of for a de Vaucouleurs
law, implying a more flattened halo.
We also derive the stellar luminosity function (SLF) for the thin disk, and
it partly agrees with the Hipparcos luminosity function.Comment: 17pages,9 figure
Age constraints for an M31 globular cluster from SEDs-fit
We have constrained the age of the globular cluster S312 in the Andromeda
galaxy (M31) by comparing its multicolor photometry with theoretical stellar
population synthesis models. This is both a check on the age of this globular
cluster, as well a check on our methodology. Main-sequence photometry has been
the most direct method for determining the age of a star cluster. S312 was
observed as part of the Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolor
Sky Survey from 1995 February to 2003 December. The photometry of BATC images
for S312 was taken with 9 intermediate-band filters covering 5000-10000\AA.
Combined with photometry in the near-ultraviolet (NUV) of {\sl GALEX},
broad-band and infrared of 2MASS, we obtained the accurate
spectral energy distributions (SEDs) of S312 from 2267-20000\AA. A quantitative
comparison to simple stellar population models yields an age of
Gyr, which is in very good agreement with the previous
determination by main-sequence photometry. S312 has a mass of
, and is a medium-mass globular cluster in
M31. By analysis of errors of ages determined based on the SED fitting method
of this paper, secure age constraints are derived with errors of Gyr for
ages younger than 9 Gyr. In fact, the theoretical SEDs are not sensitive to the
variation of age for ages greater than Gyr. Therefore, for globular
clusters as old as the majority of the Galactic GCs, our method do not
distinguish them accurately. We emphasize that our results show that even with
multiband photometry spanning NUV to , our age constraints from SED
fitting are distressingly uncertain, which has implications for age derivations
in extragalactic globular cluster systems.Comment: Accepted for Publication in ApJ, 9 pages, 5 figure
Stellar Population Properties and Evolution Analysis of NGC 628 with the Panchromatic Photometry
Panchromatic spectral energy distribution (SED) from the ultraviolet (UV),
optical to infrared (IR) photometry of NGC 628, combined with the evolutionary
stellar population synthesis, is used to derive the spatially resolved age,
metallicity and reddening maps. These parameter distributions show that the
bulge of this galaxy is a disk-like pseudobulge, which has the S{\'e}rsic index
close to the exponential law, rich gas, and a young circumnuclear ring
structure. We also discover the disk has two distinct regions with different
radial age and metallicity gradients. The inner region is older and has a much
steeper age gradient than the outer region of the disk. Both these two regions
and the central young structure can be seen in the radial profile of the
optical color. Based on the age and reddening distributions, we consider that
the pseudobulge and disk are likely to have grown via the secular evolution,
which is the redistribution of mass and energy through the angular momentum
transport caused by the non-axisymmetric potential of the spirals. However,
possible gas accretion events could affect the outer region of the disk, due to
abundant H{\sc i} gas accumulating in the outer disk.Comment: 9 figures, accepted for publication in A
Spatiotemporal genomic analysis reveals distinct molecular features in recurrent stage I non-small cell lung cancers
Stage I non-small cell lung cancer (NSCLC) presents diverse outcomes. To identify molecular features leading to tumor recurrence in early-stage NSCLC, we perform multiregional whole-exome sequencing (WES), RNA sequencing, and plasma-targeted circulating tumor DNA (ctDNA) detection analysis between recurrent and recurrent-free stage I NSCLC patients (CHN-P cohort) who had undergone R0 resection with a median 5-year follow-up time. Integrated analysis indicates that the multidimensional clinical and genomic model can stratify the prognosis of stage I NSCLC in both CHN-P and EUR-T cohorts and correlates with positive pre-surgical deep next generation sequencing (NGS) ctDNA detection. Increased genomic instability related to DNA interstrand crosslinks and double-strand break repair processes is significantly associated with early tumor relapse. This study reveals important molecular insights into stage I NSCLC and may inform clinical postoperative treatment and follow-up strategies
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