2,017 research outputs found
Algebraic higher symmetry and categorical symmetry -- a holographic and entanglement view of symmetry
We introduce the notion of algebraic higher symmetry, which generalizes
higher symmetry and is beyond higher group. We show that an algebraic higher
symmetry in a bosonic system in -dimensional space is characterized and
classified by a local fusion -category. We find another way to describe
algebraic higher symmetry by restricting to symmetric sub Hilbert space where
symmetry transformations all become trivial. In this case, algebraic higher
symmetry can be fully characterized by a non-invertible gravitational anomaly
(i.e. an topological order in one higher dimension). Thus we also refer to
non-invertible gravitational anomaly as categorical symmetry to stress its
connection to symmetry. This provides a holographic and entanglement view of
symmetries. For a system with a categorical symmetry, its gapped state must
spontaneously break part (not all) of the symmetry, and the state with the full
symmetry must be gapless. Using such a holographic point of view, we obtain (1)
the gauging of the algebraic higher symmetry; (2) the classification of
anomalies for an algebraic higher symmetry; (3) the equivalence between classes
of systems, with different (potentially anomalous) algebraic higher symmetries
or different sets of low energy excitations, as long as they have the same
categorical symmetry; (4) the classification of gapped liquid phases for
bosonic/fermionic systems with a categorical symmetry, as gapped boundaries of
a topological order in one higher dimension (that corresponds to the
categorical symmetry). This classification includes symmetry protected trivial
(SPT) orders and symmetry enriched topological (SET) orders with an algebraic
higher symmetry.Comment: 61 pages, 31 figure
Effect of graphene oxide on the thermal properties of bovine hide powders
Content:
Graphene oxide (GO) is one of the most interesting nanomaterials in recent years. In order to explore its potential application in leather making process, a study on evaluating the effects of GO on the thermal
stability and decomposition kinetics of bovine hide powders (HP) was performed by thermogravimetry. It was shown that the GO-doped hide powders (GO-HP) exhibit better thermal stability than those of raw hide powders. The kinetic and mechanism analysis of the decomposition stage used an integrated procedure involving model-free methods and universal master-plots method. Various methods were employed to calculate the activation energy of the fibers, including the Flynn-Wall-Ozawa (FWO), Modified Kissinger-Akahira-Sunose (MKAS) and Friedman methods. The activation energy values of GO-HP and raw hide powder were found to be 240.5 and 184.7 kJ/mol, respectively. Comparison of the experimental and theoretical master plots of various reaction mechanisms showed that when the conversion values are below 0.5, the most probable decomposition mechanism for HP and GO-HP is D1. Above 0.5, the decomposition mechanisms of HP and GO-HP are most probably described by A3 and R3 models,
respectively.
Take-Away:
Graphene oxide (GO) doped hide powders (GO-HP) exhibit better thermal stability than those of raw hide powders.
The activation energy values of GO-HP and raw hide powder were found to be 240.5 and 184.7 kJ/mol, respectively
Classification of topological phases with finite internal symmetries in all dimensions
We develop a mathematical theory of symmetry protected trivial (SPT) orders
and anomaly-free symmetry enriched topological (SET) orders in all dimensions
via two different approaches with an emphasis on the second approach. The first
approach is to gauge the symmetry in the same dimension by adding topological
excitations as it was done in the 2d case, in which the gauging process is
mathematically described by the minimal modular extensions of unitary braided
fusion 1-categories. This 2d result immediately generalizes to all dimensions
except in 1d, which is treated with special care. The second approach is to use
the 1-dimensional higher bulk of the SPT/SET order and the boundary-bulk
relation. This approach also leads us to a precise mathematical description and
a classification of SPT/SET orders in all dimensions. The equivalence of these
two approaches, together with known physical results, provides us with many
precise mathematical predictions.Comment: 41 pages, 6 figures; add more results on anomalies; final version to
appear in JHE
Least squares estimation of spatial autoregressive models for large-scale social networks
Due to the rapid development of various social networks, the spatial autoregressive (SAR) model is becoming an important tool in social network analysis. However, major bottlenecks remain in analyzing largescale networks (e.g., Facebook has over 700 million active users), including computational scalability, estimation consistency, and proper network sampling. To address these challenges, we propose a novel least squares estimator (LSE) for analyzing large sparse networks based on the SAR model. Computationally, the LSE is linear in the network size, making it scalable to analysis of huge networks. In theory, the LSE is root n-consistent and asymptotically normal under certain regularity conditions. A new LSE-based network sampling technique is further developed, which can automatically adjust autocorrelation between sampled and unsampled units and hence guarantee valid statistical inferences. Moreover, we generalize the LSE approach for the classical SAR model to more complex networks associated with multiple sources of social interaction effect. Numerical results for simulated and real data are presented to illustrate performance of the LSE.National Natural Science Foundation of China [71532001, 11525101, 71332006, 11701560, 11401482]; Beijing Municipal Social Science Foundation [17GLC051]; Center for Applied Statistics, School of Statistics, Renmin University of China; Center of Statistical Research, Southwestern University of Finance and Economics; China's National Key Research Special Program [2016YFC0207700]; NSF [DMS-1309507, DMS-1418172]; NSFC [11571009]Open Access JournalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Constraints on smoothness parameter and dark energy using observational data
The universe, with large-scale homogeneity, is locally inhomogeneous,
clustering into stars, galaxies and larger structures. Such property is
described by the smoothness parameter which is defined as the
proportion of matter in the form of intergalactic medium. If we take
consideration of the inhomogeneities in small scale, there should be
modifications of the cosmological distances compared to a homogenous model.
Dyer and Roeder developed a second-order ordinary differential equation (D-R
equation) that describes the angular diameter distance-redshift relation for
inhomogeneous cosmological models. Furthermore, we may obtain the D-R equation
for observational data (OHD). The density-parameter ,
the state of dark energy , and the smoothness-parameter are
constrained by a set of OHD in a spatially flat CDM universe as well
as a spatially flat XCDM universe. By using of minimization method we
get and at
confidence level. If we assume a Gaussian prior of , we get and . For XCDM model, is constrained to
but is weakly constrained around -1, where
describes the equation of the state of the dark energy (). We conclude that OHD constrains the smoothness
parameter more effectively than the data of SNe Ia and compact radio sources.Comment: 11 pages, 12 figures, accepted for publication in Research in
Astronomy and Astrophysic
Multimodal Molecular Pretraining via Modality Blending
Self-supervised learning has recently gained growing interest in molecular
modeling for scientific tasks such as AI-assisted drug discovery. Current
studies consider leveraging both 2D and 3D molecular structures for
representation learning. However, relying on straightforward alignment
strategies that treat each modality separately, these methods fail to exploit
the intrinsic correlation between 2D and 3D representations that reflect the
underlying structural characteristics of molecules, and only perform
coarse-grained molecule-level alignment. To derive fine-grained alignment and
promote structural molecule understanding, we introduce an atomic-relation
level "blend-then-predict" self-supervised learning approach, MoleBLEND, which
first blends atom relations represented by different modalities into one
unified relation matrix for joint encoding, then recovers modality-specific
information for 2D and 3D structures individually. By treating atom
relationships as anchors, MoleBLEND organically aligns and integrates visually
dissimilar 2D and 3D modalities of the same molecule at fine-grained atomic
level, painting a more comprehensive depiction of each molecule. Extensive
experiments show that MoleBLEND achieves state-of-the-art performance across
major 2D/3D molecular benchmarks. We further provide theoretical insights from
the perspective of mutual-information maximization, demonstrating that our
method unifies contrastive, generative (cross-modality prediction) and
mask-then-predict (single-modality prediction) objectives into one single
cohesive framework
Primary localized histoplasmosis with lesions restricted to the mouth in a Chinese HIV-negative patient
SummaryHistoplasmosis is a deep mycosis caused by Histoplasma capsulatum, which is endemic in many areas of the world but is relatively rare in China. Although the majority of cases present as a mild to moderate flu-like disease requiring only supportive therapy, approximately 1% of patients experience more serious pulmonary and extrapulmonary disease, which can be life-threatening if diagnosis is delayed or the treatment is not initiated rapidly. Definitive diagnosis is usually made by a combination of culture, detection of the organism in tissues, measurement of antibodies, and detection of antigen. We present the case of a 51-year-old patient who presented with histoplasmosis only, with several ulcerated lesions in the oral cavity and without HIV infection, who did not show any detectable signs and symptoms of systemic disease or extra-oral manifestations. Histopathological analysis indicated a chronic inflammatory process with granulomas with yeast-like organisms. Isolation of H. capsulatum and molecular identification provided the definitive diagnosis. Treatment with oral itraconazole led to remission of the oral lesions. This is the first Chinese case report of localized histoplasmosis with lesions restricted to the mouth in an HIV-negative patient
CryoFormer: Continuous Reconstruction of 3D Structures from Cryo-EM Data using Transformer-based Neural Representations
High-resolution heterogeneous reconstruction of 3D structures of proteins and
other biomolecules using cryo-electron microscopy (cryo-EM) is essential for
understanding fundamental processes of life. However, it is still challenging
to reconstruct the continuous motions of 3D structures from hundreds of
thousands of noisy and randomly oriented 2D cryo-EM images. Existing methods
based on coordinate-based neural networks show compelling results to model
continuous conformations of 3D structures in the Fourier domain, but they
suffer from a limited ability to model local flexible regions and lack
interpretability. We propose a novel approach, cryoFormer, that utilizes a
transformer-based network architecture for continuous heterogeneous cryo-EM
reconstruction. We for the first time directly reconstruct continuous
conformations of 3D structures using an implicit feature volume in the 3D
spatial domain. A novel deformation transformer decoder further improves
reconstruction quality and, more importantly, locates and robustly tackles
flexible 3D regions caused by conformations. In experiments, our method
outperforms current approaches on three public datasets (1 synthetic and 2
experimental) and a new synthetic dataset of PEDV spike protein. The code and
new synthetic dataset will be released for better reproducibility of our
results. Project page: https://cryoformer.github.io
Changes of plasma fibroblast growth factor-21 (FGF-21) in oral glucose tolerance test and effects of metformin on FGF-21 levels in type 2 diabetes mellitus
Wstęp: Badanie przeprowadzono w celu ustalenia, czy czynnik wzrostu fibroblastów-21 (FGF-21) uczestniczy w regulacji stężenia glukozy
i czy zastosowanie metforminy u chorych na cukrzycę wpływa na stężenie FGF-21.
Materiał i metody: Do badania włączono 43 osoby, w tym 27 chorych z nowo rozpoznaną cukrzycą typu 2 (nT2DM). U wszystkich przeprowadzono
test doustnego obciążenia 75 g glukozy (OGTT). Próbki krwi pobrano w 0., 60.,120. i 180. minucie testu. Osobom z nT2DM
zaproponowano udział w dalszych badaniach; zastosowano u nich metforminę w dawce 1,0 g/dobę przez tydzień.
Wyniki: Zmiany stężenia FGF-21 w osoczu podczas OGTT zaobserwowano tylko w grupie chorych na nT2DM; w grupie kontrolnej stężenie
FGF-21 pozostało niezmienione. Nie stwierdzono, by stężenia FGF-21 w poszczególnych punktach czasowych różniły się w zależności od płci
badanych (p < 0,05). Zastosowanie metforminy u osób z nT2DM spowodowało istotne zmniejszenie stężeń glukozy i FGF-21 we wszystkich
punktach czasowych OGTT oraz zmniejszenie stężenia insuliny w 60. i 180. minucie, co wskazuje na obniżenie wskaźnika HOMA-IR.
Wnioski: FGF-21 nie uczestniczy w krótkoterminowej regulacji glikemii u ludzi, a zmiany jego stężenia podczas OGTT są opóźnione
w T2DM. Być może FGF-21 bierze udział w metabolizowaniu metforminy, zwiększając wrażliwość na glukozę i insulinę.
(Endokrynol Pol 2013; 64 (3): 220–224)Introduction: The objectives of our study were to investigate whether fibroblast growth factor-21 (FGF-21) is involved in short-term
regulation of glucose and the change of FGF-21 after metformin use in diabetic subjects.
Material and methods: 43 subjects were recruited in the study, including 27 new-onset type 2 diabetes patients (nT2DM). A 75 g oral
glucose tolerance test (OGTT) was administered to them. Blood samples were taken at 0, 60 ,120 and 180 minute of OGTT. nT2DM subjects
were invited for further investigation, metformin was administered in a dose of 1.0 g every day for 1 week.
Results: Plasma FGF-21 changed significantly in the nT2DM group during the OGTT administration but not in the control group. No
gender differences were observed at different time points in FGF-21 levels (p < 0.05). Administration of metformin for nT2DM resulted
in a significant decrease in both glucose and FGF-21 at all OGTT times and in insulin at 60 min and 180 min, indicative of a decrease in
HOMA-IR.
Conclusion: FGF-21 does not seem to be involved in short-term regulation of glycaemia in human subjects, and the change in OGTT
delayed in T2DM. FGF-21 may participate in the processing of metformin, improving glucose and insulin sensitivity.
(Pol J Endocrinol 2013; 64 (3): 220–224
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