590 research outputs found
Simulation of CSSTs astrometric capability
The China Space Station Telescope (CSST) will enter a low Earth orbit around
2024 and operate for 10 years, with seven of those years devoted to surveying
the area of the median-to-high Galactic latitude and median-to-high Ecliptic
latitude of the sky. To maximize the scientific output of CSST, it is important
to optimize the survey schedule. We aim to evaluate the astrometric capability
of CSST for a given survey schedule and to provide independent suggestions for
the optimization of the survey strategy. For this purpose, we first construct
the astrometric model and then conduct simulated observations based on the
given survey schedule. The astrometric solution is obtained by analyzing the
simulated observation data. And then we evaluate the astrometric capability of
CSST by analyzing the properties of the astrometric solution. We find that the
accuracy of parallax and proper motion of CSST is better than 1 mas( yr1) for
the sources of 18-22 mag in g band, and about 1-10 mas( yr1) for the sources of
22-26 mag in g band, respectively. The results from real survey could be worse
since the assumptions are optimistic and simple. We find that optimizing the
survey schedule can improve the astrometric accuracy of CSST. In the future, we
will improve the astrometric capability of CSST by continuously iterating and
optimizing the survey schedule.Comment: 17 pages, 10 figure
Where to Go Next for Recommender Systems? ID- vs. Modality-based Recommender Models Revisited
Recommendation models that utilize unique identities (IDs) to represent
distinct users and items have been state-of-the-art (SOTA) and dominated the
recommender systems (RS) literature for over a decade. Meanwhile, the
pre-trained modality encoders, such as BERT and ViT, have become increasingly
powerful in modeling the raw modality features of an item, such as text and
images. Given this, a natural question arises: can a purely modality-based
recommendation model (MoRec) outperforms or matches a pure ID-based model
(IDRec) by replacing the itemID embedding with a SOTA modality encoder? In
fact, this question was answered ten years ago when IDRec beats MoRec by a
strong margin in both recommendation accuracy and efficiency. We aim to revisit
this `old' question and systematically study MoRec from several aspects.
Specifically, we study several sub-questions: (i) which recommendation
paradigm, MoRec or IDRec, performs better in practical scenarios, especially in
the general setting and warm item scenarios where IDRec has a strong advantage?
does this hold for items with different modality features? (ii) can the latest
technical advances from other communities (i.e., natural language processing
and computer vision) translate into accuracy improvement for MoRec? (iii) how
to effectively utilize item modality representation, can we use it directly or
do we have to adjust it with new data? (iv) are there some key challenges for
MoRec to be solved in practical applications? To answer them, we conduct
rigorous experiments for item recommendations with two popular modalities,
i.e., text and vision. We provide the first empirical evidence that MoRec is
already comparable to its IDRec counterpart with an expensive end-to-end
training method, even for warm item recommendation. Our results potentially
imply that the dominance of IDRec in the RS field may be greatly challenged in
the future
NineRec: A Benchmark Dataset Suite for Evaluating Transferable Recommendation
Learning a recommender system model from an item's raw modality features
(such as image, text, audio, etc.), called MoRec, has attracted growing
interest recently. One key advantage of MoRec is that it can easily benefit
from advances in other fields, such as natural language processing (NLP) and
computer vision (CV). Moreover, it naturally supports transfer learning across
different systems through modality features, known as transferable recommender
systems, or TransRec.
However, so far, TransRec has made little progress, compared to
groundbreaking foundation models in the fields of NLP and CV. The lack of
large-scale, high-quality recommendation datasets poses a major obstacle. To
this end, we introduce NineRec, a TransRec dataset suite that includes a
large-scale source domain recommendation dataset and nine diverse target domain
recommendation datasets. Each item in NineRec is represented by a text
description and a high-resolution cover image. With NineRec, we can implement
TransRec models in an end-to-end training manner instead of using pre-extracted
invariant features. We conduct a benchmark study and empirical analysis of
TransRec using NineRec, and our findings provide several valuable insights. To
support further research, we make our code, datasets, benchmarks, and
leaderboards publicly available at https://github.com/westlake-repl/NineRec
CSST forecast: impact from non-Gaussian covariances and requirements on systematics-control
The precise estimation of the statistical errors and accurate removal of the
systematical errors are the two major challenges for the stage IV cosmic shear
surveys. We explore their impact for the China Space-Station Telescope (CSST)
with survey area up to redshift . We consider
statistical error contributed from Gaussian covariance, connected non-Gaussian
covariance and super-sample covariance. We find the super-sample covariance can
largely reduce the signal-to-noise of the two-point statistics for CSST,
leading to a loss in the figure-of-merit for the matter clustering
properties ( plane) and in the dark energy
equation-of-state ( plane). We further put requirements of
systematics-mitigation on: intrinsic alignment of galaxies, baryonic feedback,
shear multiplicative bias, and bias in the redshift distribution, for an
unbiased cosmology. The to level requirements emphasize
strong needs in related studies, to support future model selections and the
associated priors for the nuisance parameters.Comment: submitted to MNRA
New high-resolution estimates of the permafrost thermal state and hydrothermal conditions over the Northern Hemisphere
Monitoring the thermal state of permafrost (TSP) is important in many environmental science and engineering applications. However, such data are generally unavailable, mainly due to the lack of ground observations and the uncertainty of traditional physical models. This study produces novel permafrost datasets for the Northern Hemisphere (NH), including predictions of the mean annual ground temperature (MAGT) at the depth of zero annual amplitude (DZAA) (approximately 3 to 25 m) and active layer thickness (ALT) with 1 km resolution for the period of 2000-2016, as well as estimates of the probability of permafrost occurrence and permafrost zonation based on hydrothermal conditions. These datasets integrate unprecedentedly large amounts of field data (1002 boreholes for MAGT and 452 sites for ALT) and multisource geospatial data, especially remote sensing data, using statistical learning modeling with an ensemble strategy. Thus, the resulting data are more accurate than those of previous circumpolar maps (bias = 0 :02 +/- 0 :16 degrees C and RMSE = 1 :32 +/- 0 :13 degrees C for MAGT; bias = 2 :71 +/- 16 :46 cm and RMSE = 86 :93 +/- 19 :61 cm for ALT). The datasets suggest that the areal extent of permafrost (MAGT 0) is approximately 19 :82 x 10(6) km(2). The areal fractions of humid, semiarid/subhumid, and arid permafrost regions are 51.56 %, 45.07 %, and 3.37 %, respectively. The areal fractions of cold ( 1 :5 degrees C) permafrost regions are 37.80 %, 14.30 %, and 47.90 %, respectively. These new datasets based on the most comprehensive field data to date contribute to an updated understanding of the thermal state and zonation of permafrost in the NH. The datasets are potentially useful for various fields, such as climatology, hydrology, ecology, agriculture, public health, and engineering planning. All of the datasets are published through the National Tibetan Plateau Data Center (TPDC), and the link is https://doi.org/10.11888/Geocry.tpdc.271190 (Ran et al., 2021a).Peer reviewe
Pulse Diagnosis Signals Analysis of Fatty Liver Disease and Cirrhosis Patients by Using Machine Learning
Objective. To compare the signals of pulse diagnosis of fatty liver disease (FLD) patients and cirrhosis patients. Methods. After collecting the pulse waves of patients with fatty liver disease, cirrhosis patients, and healthy volunteers, we do pretreatment and parameters extracting based on harmonic fitting, modeling, and identification by unsupervised learning Principal Component Analysis (PCA) and supervised learning Least squares Regression (LS) and Least Absolute Shrinkage and Selection Operator (LASSO) with cross-validation step by step for analysis. Results. There is significant difference between the pulse diagnosis signals of healthy volunteers and patients with FLD and cirrhosis, and the result was confirmed by 3 analysis methods. The identification accuracy of the 1st principal component is about 75% without any classification formation by PCA, and supervised learning’s accuracy (LS and LASSO) was even more than 93% when 7 parameters were used and was 84% when only 2 parameters were used. Conclusion. The method we built in this study based on the combination of unsupervised learning PCA and supervised learning LS and LASSO might offer some confidence for the realization of computer-aided diagnosis by pulse diagnosis in TCM. In addition, this study might offer some important evidence for the science of pulse diagnosis in TCM clinical diagnosis
To compare the efficacy of two kinds of Zhizhu pills in the treatment of functional dyspepsia of spleen-deficiency and qi-stagnation syndrome:a randomized group sequential comparative trial
<p>Abstract</p> <p>Background</p> <p>In Traditional Chinese Medicine (TCM) theory, functional dyspepsia (FD) can be divided into different syndromes according to different clinical symptoms and signs, and the most common one is spleen-deficiency and qi-stagnation syndrome that can be treated by Chinese traditional patent medicine ---- two kinds of Zhizhu pills, between which the primary difference in ingredients is that one contains immature orange fruit of Citrus aurantium L.(IFCA) and the other contains that of Citrus sinensis Osbeck (IFCS). The trial's objective was to compare the efficacy of two kinds of Zhizhu pills on symptom changes in patients with FD of spleen-deficiency and qi-stagnation syndrome.</p> <p>Methods</p> <p>A randomized, group sequential, double-blinded, multicenter trial was conducted in patients with FD of spleen-deficiency and qi-stagnation syndrome at 3 hospitals in Beijing between June 2003 and May 2005. Participants were randomly allocated into two groups (IFCA group and IFCS group) in a 1:1 ratio, and respectively took one of the two kinds of Zhizhu pills orally, 6 g each time, 3 times a day, for 4 weeks. Statistical analysis was performed with use of a group sequential method, the triangular test (TT).</p> <p>Results</p> <p>A total of 163 patients were randomized, and 3 patients were excluded from analysis because of early dropouts, leaving 160 patients (IFCA group: n = 82; IFCS group: n = 78) for statistical analysis. Three interim analyses were done after 62, 116, and 160 patients had completed their 4-week treatment, respectively. At the third interim analysis, the sample path crossed the upper boundary and the trial was stopped, the cure-markedly effective rates were 45% for IFCS group and 67% for IFCA group, respectively, the one-sided <it>p</it>-value was 0.0036, the median unbiased estimate of the odds ratio (OR) for the benefit of IFCA relative to IFCS was 2.91 with 95%CI: 1.40 to 6.06.</p> <p>No adverse events were observed in the two groups.</p> <p>Conclusions</p> <p>Zhizhu pills containing IFCA was superior to Zhizhu pills containing IFCS in the treatment of FD of spleen-deficiency and qi-stagnation syndrome. The application of group sequential analysis in clinical trials of TCM may offer some financial and ethical benefits.</p> <p>Trial Registration</p> <p>Chinese Clinical Trial Registry (ChiCTR): ChiCTR-TRC-00000485</p
Multidifferential study of identified charged hadron distributions in -tagged jets in proton-proton collisions at 13 TeV
Jet fragmentation functions are measured for the first time in proton-proton
collisions for charged pions, kaons, and protons within jets recoiling against
a boson. The charged-hadron distributions are studied longitudinally and
transversely to the jet direction for jets with transverse momentum 20 GeV and in the pseudorapidity range . The
data sample was collected with the LHCb experiment at a center-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 1.64 fb. Triple
differential distributions as a function of the hadron longitudinal momentum
fraction, hadron transverse momentum, and jet transverse momentum are also
measured for the first time. This helps constrain transverse-momentum-dependent
fragmentation functions. Differences in the shapes and magnitudes of the
measured distributions for the different hadron species provide insights into
the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb
public pages
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
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