检索结果-内蒙古大学图书馆

Parametric estimation for convolutionally observed diffusion processes

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Nakakita, Shogo H. Uchida, Masayuki Graduate School of Engineering Science Osaka University Center for Mathematical Modeling and Data Science Osaka University

We propose a new statistical observation scheme of diffusion processes named convolutional observation, where it is possible to deal with smoother observation than ordinary diffusion processes by considering convolution of diffusion processes and some kernel functions with respect to time parameter. We discuss the estimation and test theories for the parameter determining the smoothness of the observation, as well as the least-square-type estimation for the parameters in the diffusion coefficient and the drift one of the latent diffusion process. In addition to the theoretical discussion, we also examine the performance of the estimation and the test with computational simulation, and show an example of real data analysis for one EEG data whose observation can be regarded as smoother one than ordinary diffusion processes with statistical significance. Copyright © 2019, The Authors. All rights reserved.

关键词： Convolution

Surface localization of plasmons in three dimensions and convexity

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Ando, Kazunori Kang, Hyeonbae Miyanishi, Yoshihisa Nakazawa, Takashi Department of Electrical and Electronic Engineering and Computer Science Ehime University Ehime790-8577 Japan Department of Mathematics Institute of Applied Mathematics Inha University Incheon22212 Korea Republic of Center for Mathematical Modeling and Data Science Osaka University Osaka560-8531 Japan

The Neumann–Poincaré operator defined on a smooth surface has a sequence of eigenvalues converging to zero, and the single layer potentials of the corresponding eigenfunctions, called plasmons, decay to zero, i.e., are localized on the surface, as the index of the sequence j tends to infinity. We investigate quantitatively the surface localization of the plasmons in three dimensions. The results are threefold. We first prove that on smooth bounded domains of general shape the sequence of plasmons converges to zero off the boundary surface almost surely at the rate of j−1/2. We then prove that if the domain is strictly convex, then the convergence rate becomes j−∞, namely, it is faster than j−N for any integer N. As a consequence, we prove that cloaking by anomalous localized resonance does not occur on three-dimensional strictly convex smooth domains. We then look into the surface localization of the plasmons on the Clifford torus by numerical computations. The Clifford torus is taken as an example of non-convex surfaces. The computational results show that the torus exhibits the spectral property completely different from strictly convex domains. In particular, they suggest that there is a subsequence of plasmons on the torus which has much slower decay than other entries of the *** Codes 35J47 (primary), 35P05 (secondary). Copyright © 2020, The Authors. All rights reserved.

关键词： Plasmons

Spectral structure of the Neumann–Poincaré operator on thin domains in two dimensions∗

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Ando, Kazunori Kang, Hyeonbae Miyanishi, Yoshihisa Department of Electrical and Electronic Engineering and Computer Science Ehime University Ehime790-8577 Japan Department of Mathematics Institute of Applied Mathematics Inha University Incheon22212 Korea Republic of Center for Mathematical Modeling and Data Science Osaka University Osaka560-8531 Japan

We consider the spectral structure of the Neumann–Poincaré operators defined on the boundaries of thin domains of rectangle shape in two dimensions. We prove that as the aspect ratio of the domains tends to ∞, or equivalently, as the domains get thinner, the spectra of the Neumann–Poincaré operators are densely distributed in the interval [−1/2, 1/2].MSC Codes 35J47, 35P05 Copyright © 2020, The Authors. All rights reserved.

关键词： Aspect ratio

ALeRCE light curve classifier: Tidal disruption event expansion pack

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Pavez-Herrera, M. Sánchez-Sáez, P. Hernández-García, L. Bauer, F.E. Förster, F. Catelan, M. Arancibia, A. Muñoz Ricci, C. Reyes-Jainaga, I. Bayo, A. Huijse, P. Cabrera-Vives, G. Instituto de Astrofísica Facultad de Física Pontificia Universidad Católica de Chile Campus San Joaquín Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Nuncio Monseñor Sótero Sanz 100 Providencia Santiago Chile Departamento de Astronomía Universidad de Chile Casilla 36D Santiago Chile European Southern Observatory Karl-Schwarzschild-Strasse 2 Garching bei München85748 Germany Concepción4030000 Chile Instituto de Física y Astronomía Facultad de Ciencias Universidad de Valparaíso Gran Bretana 1111 Playa Ancha Valparaíso Chile Centro de Astroingeniería Facultad de Física Pontificia Universidad Católica de Chile Campus San Joaquín Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Space Science Institute 4750 Walnut Street Suite 205 BoulderCO80301 United States Faculty of Physical and Mathematical Sciences Universidad de Chile Chile Center for Mathematical Modeling Universidad de Chile Beauchef 851 Santiago8370456 Chile Instituto de Estudios Astrofísicos Facultad de Ingeniería y Ciencias Universidad Diego Portales Av. Ejército Libertador 441 Santiago Chile Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Data Observatory Foundation Santiago Chile Institute of Astronomy KU Leuven Celestijnenlaan 200D LeuvenB-3001 Belgium Department of Computer Science Universidad de Concepción Concepción Chile Data Science Unit Universidad de Concepción Edmundo Larenas 310 Concepción Chile

Context. ALeRCE (Automatic Learning for the Rapid Classification of Events) is currently processing the Zwicky Transient Facility (ZTF) alert stream, in preparation for the Vera C. Rubin Observatory, and classifying objects using a broad taxonomy. The ALeRCE light curve classifier is a balanced random forest (BRF) algorithm with a two-level scheme that uses variability features computed from the ZTF alert stream, and colors obtained from AllWISE and ZTF photometry. Aims. This work develops an updated version of the ALeRCE broker light curve classifier that includes tidal disruption events (TDEs) as a new subclass. For this purpose we incorporated 24 new features, notably including the distance to the nearest source detected in ZTF science images and a parametric model of the power-law decay for transients. We also expanded the labeled set to include 219,792 spectroscopically classified sources, including 60 TDEs. Methods. To effectively integrate TDEs into the ALeRCE’s taxonomy, we identified specific characteristics that set them apart from other transient classes, such as their central position in a galaxy, the typical decay pattern displayed when fully disrupted, and the lack of color variability after disruption. Based on these attributes, we developed features to distinguish TDEs from other transient events. Results. The modified classifier can distinguish between a broad range of classes with a better performance compared to the previous version and it can integate the TDE class achieving 91% recall, also identifying a large number of potential TDE candidates in ZTF alert stream unlabeled data. © 2025, CC BY.

关键词： Taxonomies

Multi-scale stamps for real-time classification of alert streams

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Reyes-Jainaga, Ignacio Förster, Francisco Muñoz Arancibia, Alejandra M. Cabrera-Vives, Guillermo Bayo, Amelia Bauer, Franz E. Arredondo, Javier Reyes, Esteban Pignata, Giuliano Mourão, A.M. Silva-Farfán, Javier Galbany, Lluís Álvarez, Alex Astorga, Nicolás Castellanos, Pablo Gallardo, Pedro Moya, Alberto Rodríguez, Diego Center for Mathematical Modeling Universidad de Chile Beauchef 851 Santiago8370456 Chile Millennium Institute of Astrophysics Nuncio Monseñor Sótero Sanz 100 Providencia Santiago Chile Faculty of Physical and Mathematical Sciences Universidad de Chile Chile Departamento de Astronomía Universidad de Chile Chile Department of Computer Science Universidad de Concepción Concepción Chile Data Science Unit Universidad de Concepción Concepción Chile Instituto de Física y Astronomía Universidad de Valparaíso Chile European Southern Observatory Karl-Schwarzschild-Strasse 2 Garching bei München85748 Germany Instituto de Astrofísica Centro de Astroingeniería Facultad de Física Pontificia Universidad Católica de Chile Casilla 306 Santiago22 Chile NeuralWorks Santiago Chile Fintual Administradora General de Fondos S.A. Santiago Chile Instituto de Astrofísica Facultad de Ciencias Exactas Universidad Andres Bello Avda. Fernéndez Concha 700 Las Condes Chile Departamento de Física and CENTRA Center for Astrophysics and Gravitation Instituto Superior Técnico Universidade de Lisboa Portugal Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain BarcelonaE-08034 Spain Department of Electrical Engineering Universidad de Chile Av. Tupper 2007 Santiago8320000 Chile University of Chile Chile Data Observatory Foundation Santiago Chile

In recent years, automatic classifiers of image cutouts (also called "stamps") have shown to be key for fast supernova discovery. The Vera C. Rubin Observatory will distribute about ten million alerts with their respective stamps each night, enabling the discovery of approximately one million supernovae each year. A growing source of confusion for these classifiers is the presence of satellite glints, sequences of point-like sources produced by rotating satellites or debris. The currently planned Rubin stamps will have a size smaller than the typical separation between these point sources. Thus, a larger field of view stamp could enable the automatic identification of these sources. However, the distribution of larger stamps would be limited by network bandwidth restrictions. We evaluate the impact of using image stamps of different angular sizes and resolutions for the fast classification of events (AGNs, asteroids, bogus, satellites, SNe, and variable stars), using data from the Zwicky Transient Facility. We compare four scenarios: three with the same number of pixels (small field of view with high resolution, large field of view with low resolution, and a multi-scale proposal) and a scenario with the full stamp that has a larger field of view and higher resolution. Compared to small field of view stamps, our multi-scale strategy reduces misclassifications of satellites as asteroids or supernovae, performing on par with high-resolution stamps that are 15 times heavier. We encourage Rubin and its science Collaborations to consider the benefits of implementing multi-scale stamps as a possible update to the alert specification. © 2023, CC BY.

关键词： Supernovae

A novel optimal transport-based approach for interpolating spectral time series Paving the way for photometric classification of supernovae

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Ramirez, M. Pignata, G. Förster, Francisco González-Gaitán, Santiago Gutiérrez, Claudia P. Ayala, B. Cabrera-Vives, Guillermo Catelan, Márcio Arancibia, A.M. Muñoz Pineda-García, J. Instituto de Astrofisica Departamento de Fisica Facultad de Ciencias Exactas Universidad Andres Bello Fernandez Concha 700 Las Condes RM Santiago Chile Millennium Institute of Astrophysics Nuncio Monseñor Sotero Sanz 100 Of. 104 Providencia Santiago Chile Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile Faculty of Physical and Mathematical Sciences Universidad de Chile Chile Center for Mathematical Modeling Universidad de Chile Beauchef 851 Santiago8370456 Chile Departamento de Astronomía Universidad de Chile Chile CENTRA Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1 Lisboa1049-001 Portugal Instituto de Astrofísica Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Centro de Astroingeniería Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Gran Capità 2-4 Edifici Nexus Desp. 201 BarcelonaE-08034 Spain Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain Department of Computer Science Universidad de Concepción Chile Data Science Unit Universidad de Concepción Edmundo Larenas 310 Concepción Chile

Context. The Vera C. Rubin Observatory is set to discover 1 million supernovae (SNe) within its first operational year. Given the impracticality of spectroscopic classification at such scales, it is mandatory to develop a reliable photometric classification framework. Aims. This paper introduces a novel method for creating spectral time series that can be used not only to generate synthetic light curves for photometric classification, but also in applications such as K-corrections and bolometric corrections. This approach is particularly valuable in the era of large astronomical surveys, where it can significantly enhance the analysis and understanding of an increasing number of SNe, even in the absence of extensive spectroscopic data. Methods. By employing interpolations based on optimal transport theory, starting from a spectroscopic sequence, we derive weighted average spectra with high cadence. The weights incorporate an uncertainty factor for penalizing interpolations between spectra that show significant epoch differences and lead to a poor match between the synthetic and observed photometry. Results. Our analysis reveals that even with a phase difference of up to 40 days between pairs of spectra, optical transport can generate interpolated spectral time series that closely resemble the original ones. Synthetic photometry extracted from these spectral time series aligns well with observed photometry. The best results are achieved in the V band, with relative residuals of less than 10% for 87% and 84% of the data for type Ia and II, respectively. For the B, g, R, and r bands, the relative residuals are between 65% and 87% within the previously mentioned 10% threshold for both classes. The worse results correspond to the i and I bands, where, in the case of SN Ia, the values drop to 53% and 42%, respectively. Conclusions. We introduce a new method for constructing spectral time series for individual SNe starting from a sparse spectroscopic sequence, and demonstr

关键词： Supernovae

A cellular hierarchy in melanoma uncouples growth and metastasis

学校读者我要写书评

暂无评论

四川生理科学杂志 2022年第9期44卷 1633-1633页

作者： Panagiotis Karras Laboratory for Molecular Cancer Biology Center for Cancer Biology VIB Leuven Belgium Department of Oncology KU Leuven Leuven Belgium Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences University of Cambridge Cambridge UK The Wellcome Trust/CRUK Gurdon Institute University of Cambridge Cambridge UK Department of General Medical Oncology UZ Leuven Leuven Belgium BGI-Shenzhen Shenzhen China VIB BioImaging Core VIB Center for Brain and Disease Research Leuven Belgium VIB Bioimaging Core VIB Center for Inflammation Research Ghent Belgium Department of Biomedical Molecular Biology Ghent University Ghent Belgium FACS Expertise Center Center for Cancer Biology VIB Leuven Belgium Laboratory of Tumor Microenvironment and Therapeutic Resistance Center for Cancer Biology VIB Leuven Belgium Center for Brain & Disease Research VIB-KU Leuven Leuven Belgium Department of Human Genetics KU Leuven Leuven Belgium Data Mining and Modeling for Biomedicine Group VIB Center for Inflammation Research Ghent Belgium Department of Applied Mathematics Computer Science and Statistics Ghent University Ghent Belgium Laboratory for Translational Cell and Tissue Research Department of Imaging and Pathology KU Leuven Leuven Belgium Laboratory of Translational Genetics Center for Cancer Biology VIB Leuven Belgium Laboratory of Translational Genetics Center for Human Genetics KU Leuven Leuven Belgium Herbert Irving Comprehensive Center Columbia University Irving Medical Center New York USA Laboratory of Stem Cells and Cancer Université Libre de Bruxelles (ULB) Brussels Belgium Wellcome Trust-MRC Stem Cell Institute University of Cambridge Cambridge UK

Although melanoma is notorious for its high degree of heterogeneity and plasticity1,2,the origin and magnitude of cell-state diversity remains poorly ***,it is unclear whether growth and metastatic dissemination are supported by overlapping or distinct melanoma ***,by combining mouse genetics,single-cell and spatial transcriptomics,lineage tracing and quantitative modelling,we provide evidence of a hierarchical model of tumour growth that mirrors the cellular and molecular logic underlying the cell-fate specification and differentiation of the embryonic neural *** show that tumorigenic competence is associated with a spatially localized perivascular niche,a phenotype acquired through an intercellular communication pathway established by endothelial *** with a model in which only a fraction of cells are fated to fuel growth,temporal single-cell tracing of a population of melanoma cells with a mesenchymal-like state revealed that these cells do not contribute to primary tumour growth but,instead,constitute a pool of metastatic initiating cells that switch cell identity while disseminating to secondary *** data provide a spatially and temporally resolved map of the diversity and trajectories of melanoma cell states and suggest that the ability to support growth and metastasis are limited to distinct pools of *** observation that these phenotypic competencies can be dynamically acquired after exposure to specific niche signals warrant the development of therapeutic strategies that interfere with the cancer cell reprogramming activity of such microenvironmental cues.

关键词： melanoma metastasis organs

Spectral analysis of neumann-poincaré operator

学校读者我要写书评

暂无评论

arXiv 2020年

作者： ANDO, KAZUNORI KANG, HYEONBAE MIYANISHI, YOSHIHISA PUTINAR, MIHAI Department of Electrical and Electronic Engineering and Computer Science Ehime University Ehime790-8577 Japan Department of Mathematics Inha University Incheon402-751 Korea Republic of University of California Santa BarbaraCA93106 United States Newcastle University Newcastle upon TyneNE1 7RU United Kingdom Center for Mathematical Modeling and Data Science Osaka University Japan

This is a survey of accumulated spectral analysis observations spanning more than a century, referring to the double layer potential integral equation, also known as Neumann-Poincaré operator. The very notion of spectral analysis has evolved along this path. Indeed, the quest for solving this specific singular integral equation, originally aimed at elucidating classical potential theory problems, has inspired and shaped the development of theoretical spectral analysis of linear transforms in XX-th century. We briefly touch some marking discoveries into the subject, with ample bibliographical references to both old, sometimes forgotten, texts and new contributions. It is remarkable that applications of the spectral analysis of the Neumann-Poincaré operator are still uncovered nowadays, with spectacular impacts on applied science. A few modern ramifications along these lines are depicted in our survey. Copyright © 2020, The Authors. All rights reserved.

关键词： Spectrum analysis

A cellular hierarchy in melanoma uncouples growth and metastasis (vol 610, pg 190, 2022)

学校读者我要写书评

暂无评论

NATURE 2022年第7934期611卷 E4-E4页

作者： Karras, Panagiotis Bordeu, Ignacio Pozniak, Joanna Nowosad, Ada Pazzi, Cecilia Van Raemdonck, Nina Landeloos, Ewout Van Herck, Yannick Pedri, Dennis Bervoets, Greet Makhzami, Samira Khoo, Jia Hui Pavie, Benjamin Lamote, Jochen Marin-Bejar, Oskar Dewaele, Michael Liang, Han Zhang, Xingju Hua, Yichao Wouters, Jasper Browaeys, Robin Bergers, Gabriele Saeys, Yvan Bosisio, Francesca van den Oord, Joost Lambrechts, Diether Rustgi, Anil K. Bechter, Oliver Blanpain, Cedric Simons, Benjamin D. Rambow, Florian Marine, Jean-Christophe Laboratory for Molecular Cancer Biology Center for Cancer Biology VIB Leuven Belgium Department of Oncology KU Leuven Leuven Belgium Laboratory of Tumor Microenvironment and Therapeutic Resistance Center for Cancer Biology VIB Leuven Belgium Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences University of Cambridge Cambridge UK The Wellcome Trust/CRUK Gurdon Institute University of Cambridge Cambridge UK Wellcome Trust-MRC Stem Cell Institute University of Cambridge Cambridge UK Department of General Medical Oncology UZ Leuven Leuven Belgium BGI-Shenzhen Shenzhen China VIB BioImaging Core VIB Center for Brain and Disease Research Leuven Belgium VIB Bioimaging Core VIB Center for Inflammation Research Ghent Belgium Department of Biomedical Molecular Biology Ghent University Ghent Belgium FACS Expertise Center Center for Cancer Biology VIB Leuven Belgium Center for Brain & Disease Research VIB-KU Leuven Leuven Belgium Department of Human Genetics KU Leuven Leuven Belgium Data Mining and Modeling for Biomedicine Group VIB Center for Inflammation Research Ghent Belgium Department of Applied Mathematics Computer Science and Statistics Ghent University Ghent Belgium Laboratory for Translational Cell and Tissue Research Department of Imaging and Pathology KU Leuven Leuven Belgium Laboratory of Translational Genetics Center for Cancer Biology VIB Leuven Belgium Laboratory of Translational Genetics Center for Human Genetics KU Leuven Leuven Belgium Herbert Irving Comprehensive Center Columbia University Irving Medical Center New York USA Laboratory of Stem Cells and Cancer Université Libre de Bruxelles (ULB) Brussels Belgium