Kai Zhang - Key Laboratory for Research in Galaxies and Cosmology, The University of Sciences and Technology of China

Kai Zhang
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Kai Zhang
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Key Laboratory for Research in Galaxies and Cosmology, The University of Sciences and Technology of China
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Astrophysics of Galaxies (12)
 
Physics - Materials Science (9)
 
Physics - Soft Condensed Matter (6)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (5)
 
Instrumentation and Methods for Astrophysics (5)
 
Statistics - Methodology (4)
 
Computer Science - Learning (4)
 
Statistics - Machine Learning (4)
 
Statistics - Theory (3)
 
Computer Science - Cryptography and Security (3)
 
Computer Science - Computer Vision and Pattern Recognition (3)
 
Physics - Statistical Mechanics (3)
 
Mathematics - Statistics (3)
 
Computer Science - Information Theory (2)
 
Mathematics - Information Theory (2)
 
Physics - Data Analysis; Statistics and Probability (1)
 
Mathematics - Mathematical Physics (1)
 
Physics - Optics (1)
 
Physics - Medical Physics (1)
 
Physics - Plasma Physics (1)
 
Mathematical Physics (1)
 
Cosmology and Nongalactic Astrophysics (1)
 
Computer Science - Artificial Intelligence (1)
 
Statistics - Computation (1)
 
Physics - Strongly Correlated Electrons (1)
 
Physics - Chemical Physics (1)
 
Computer Science - Distributed; Parallel; and Cluster Computing (1)
 
Physics - Superconductivity (1)
 
Mathematics - Rings and Algebras (1)

Publications Authored By Kai Zhang

Amorphous materials such as metallic, polymeric, and colloidal glasses, exhibit complex preparation-dependent mechanical response to applied shear. We perform numerical simulations to investigate the mechanical response of binary Lennard-Jones glasses undergoing athermal, quasistatic pure shear as a function of the cooling rate $R$ used to prepare them. The ensemble-averaged stress versus strain curve $\langle\sigma(\gamma)\rangle$ resembles the spatial average in the large size limit, which appears smooth and displays a putative elastic regime at small strains, a yielding-related peak at intermediate strain, and a plastic flow regime at large strains. Read More

In the coded caching framework proposed by Maddah Ali and Niesen, there are two classes of coding schemes known in the literature, namely uncoded prefetching schemes and coded prefetching schemes. In this work, we provide a connection between the uncoded prefetching scheme proposed by Maddah Ali and Niesen (and its improved version by Yu et al.) and the coded prefetching scheme proposed by Tian and Chen, when the number of files is no larger than that of users. Read More

Model-based optimization methods and discriminative learning methods have been the two dominant strategies for solving various inverse problems in low-level vision. Typically, those two kinds of methods have their respective merits and drawbacks, e.g. Read More

Recent years have witnessed great success of convolutional neural network (CNN) for various problems both in low and high level visions. Especially noteworthy is the residual network which was originally proposed to handle high-level vision problems and enjoys several merits. This paper aims to extend the merits of residual network, such as skip connection induced fast training, for a typical low-level vision problem, i. Read More

We report a post-growth aging mechanism of Bi$_2$Te$_3$(111) films with scanning tunneling microscopy in combination with density functional theory calculation. It is found that a monolayered structure with a squared lattice symmetry gradually aggregates from surface steps. Theoretical calculations indicate that the van der Waals (vdW) gap not only acts as a natural reservoir for self-intercalated Bi and Te atoms, but also provides them easy diffusion pathways. Read More

2017Feb
Authors: Michael R. Blanton, Matthew A. Bershady, Bela Abolfathi, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Javier Alonso-García, Friedrich Anders, Scott F. Anderson, Brett Andrews, Erik Aquino-Ortíz, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Kathleen A. Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Dominic Bates, Falk Baumgarten, Julian Bautista, Rachael Beaton, Timothy C. Beers, Francesco Belfiore, Chad F. Bender, Andreas A. Berlind, Mariangela Bernardi, Florian Beutler, Jonathan C. Bird, Dmitry Bizyaev, Guillermo A. Blanc, Michael Blomqvist, Adam S. Bolton, Médéric Boquien, Jura Borissova, Remco van den Bosch, Jo Bovy, William N. Brandt, Jonathan Brinkmann, Joel R. Brownstein, Kevin Bundy, Adam J. Burgasser, Etienne Burtin, Nicolás G. Busca, Michele Cappellari, Maria Leticia Delgado Carigi, Joleen K. Carlberg, Aurelio Carnero Rosell, Ricardo Carrera, Brian Cherinka, Edmond Cheung, Yilen Gómez Maqueo Chew, Cristina Chiappini, Peter Doohyun Choi, Drew Chojnowski, Chia-Hsun Chuang, Haeun Chung, Rafael Fernando Cirolini, Nicolas Clerc, Roger E. Cohen, Johan Comparat, Luiz da Costa, Marie-Claude Cousinou, Kevin Covey, Jeffrey D. Crane, Rupert A. C. Croft, Irene Cruz-Gonzalez, Daniel Garrido Cuadra, Katia Cunha, Guillermo J. Damke, Jeremy Darling, Roger Davies, Kyle Dawson, Axel de la Macorra, Nathan De Lee, Timothée Delubac, Francesco Di Mille, Aleks Diamond-Stanic, Mariana Cano-Díaz, John Donor, Juan José Downes, Niv Drory, Hélion du Mas des Bourboux, Christopher J. Duckworth, Tom Dwelly, Jamie Dyer, Garrett Ebelke, Daniel J. Eisenstein, Eric Emsellem, Mike Eracleous, Stephanie Escoffier, Michael L. Evans, Xiaohui Fan, Emma Fernández-Alvar, J. G. Fernandez-Trincado, Diane K. Feuillet, Alexis Finoguenov, Scott W. Fleming, Andreu Font-Ribera, Alexander Fredrickson, Gordon Freischlad, Peter M. Frinchaboy, Lluís Galbany, R. Garcia-Dias, D. A. García-Hernández, Patrick Gaulme, Doug Geisler, Joseph D. Gelfand, Héctor Gil-Marín, Bruce A. Gillespie, Daniel Goddard, Violeta Gonzalez-Perez, Kathleen Grabowski, Paul J. Green, Catherine J. Grier, James E. Gunn, Hong Guo, Julien Guy, Alex Hagen, ChangHoon Hahn, Matthew Hall, Paul Harding, Sten Hasselquist, Suzanne L. Hawley, Fred Hearty, Jonay I. Gonzalez Hernández, Shirley Ho, David W. Hogg, Kelly Holley-Bockelmann, Jon A. Holtzman, Parker H. Holzer, Joseph Huehnerhoff, Timothy A. Hutchinson, Ho Seong Hwang, Héctor J. Ibarra-Medel, Gabriele da Silva Ilha, Inese I. Ivans, KeShawn Ivory, Kelly Jackson, Trey W. Jensen, Jennifer A. Johnson, Amy Jones, Henrik Jönsson, Eric Jullo, Vikrant Kamble, Karen Kinemuchi, David Kirkby, Francisco-Shu Kitaura, Mark Klaene, Gillian R. Knapp, Jean-Paul Kneib, Juna A. Kollmeier, Ivan Lacerna, Richard R. Lane, Dustin Lang, David R. Law, Daniel Lazarz, Jean-Marc Le Goff, Fu-Heng Liang, Cheng Li, Hongyu LI, Marcos Lima, Lihwai Lin, Yen-Ting Lin, Sara Bertran de Lis, Chao Liu, Miguel Angel C. de Icaza Lizaola, Dan Long, Sara Lucatello, Britt Lundgren, Nicholas K. MacDonald, Alice Deconto Machado, Chelsea L. MacLeod, Suvrath Mahadevan, Marcio Antonio Geimba Maia, Roberto Maiolino, Steven R. Majewski, Elena Malanushenko, Viktor Malanushenko, Arturo Manchado, Shude Mao, Claudia Maraston, Rui Marques-Chaves, Karen L. Masters, Cameron K. McBride, Richard M. McDermid, Brianne McGrath, Ian D. McGreer, Nicolás Medina Peña, Matthew Melendez, Andrea Merloni, Michael R. Merrifield, Szabolcs Meszaros, Andres Meza, Ivan Minchev, Dante Minniti, Takamitsu Miyaji, Surhud More, John Mulchaey, Francisco Müller-Sánchez, Demitri Muna, Ricardo R. Munoz, Adam D. Myers, Preethi Nair, Kirpal Nandra, Janaina Correa do Nascimento, Alenka Negrete, Melissa Ness, Jeffrey A. Newman, Robert C. Nichol, David L. Nidever, Christian Nitschelm, Pierros Ntelis, Julia E. O'Connell, Ryan J. Oelkers, Audrey Oravetz, Daniel Oravetz, Zach Pace, Nelson Padilla, Nathalie Palanque-Delabrouille, Pedro Alonso Palicio, Kaike Pan, Taniya Parikh, Isabelle Pâris, Changbom Park, Alim Y. Patten, Sebastien Peirani, Marcos Pellejero-Ibanez, Samantha Penny, Will J. Percival, Ismael Perez-Fournon, Patrick Petitjean, Matthew M. Pieri, Marc Pinsonneault, Alice Pisani, Radosław Poleski, Francisco Prada, Abhishek Prakash, Anna Bárbara de Andrade Queiroz, M. Jordan Raddick, Anand Raichoor, Sandro Barboza Rembold, Hannah Richstein, Rogemar A. Riffel, Rogério Riffel, Hans-Walter Rix, Annie C. Robin, Constance M. Rockosi, Sergio Rodríguez-Torres, A. Roman-Lopes, Carlos Román-Zúñiga, Margarita Rosado, Ashley J. Ross, Graziano Rossi, John Ruan, Rossana Ruggeri, Eli S. Rykoff, Salvador Salazar-Albornoz, Mara Salvato, Ariel G. Sánchez, David Sánchez Aguado, José R. Sánchez-Gallego, Felipe A. Santana, Basílio Xavier Santiago, Conor Sayres, Ricardo P. Schiavon, Jaderson da Silva Schimoia, Edward F. Schlafly, David J. Schlegel, Donald P. Schneider, Mathias Schultheis, William J. Schuster, Axel Schwope, Hee-Jong Seo, Zhengyi Shao, Shiyin Shen, Matthew Shetrone, Michael Shull, Joshua D. Simon, Danielle Skinner, M. F. Skrutskie, Anže Slosar, Verne V. Smith, Jennifer S. Sobeck, Flavia Sobreira, Garrett Somers, Diogo Souto, David V. Stark, Keivan Stassun, Fritz Stauffer, Matthias Steinmetz, Thaisa Storchi-Bergmann, Alina Streblyanska, Guy S. Stringfellow, Genaro Suárez, Jing Sun, Nao Suzuki, Laszlo Szigeti, Manuchehr Taghizadeh-Popp, Baitian Tang, Charling Tao, Jamie Tayar, Mita Tembe, Johanna Teske, Aniruddha R. Thakar, Daniel Thomas, Benjamin A. Thompson, Jeremy L. Tinker, Patricia Tissera, Rita Tojeiro, Hector Hernandez Toledo, Sylvain de la Torre, Christy Tremonti, Nicholas W. Troup, Octavio Valenzuela, Inma Martinez Valpuesta, Jaime Vargas-González, Mariana Vargas-Magaña, Jose Alberto Vazquez, Sandro Villanova, M. Vivek, Nicole Vogt, David Wake, Rene Walterbos, Yuting Wang, Benjamin Alan Weaver, Anne-Marie Weijmans, David H. Weinberg, Kyle B. Westfall, David G. Whelan, Vivienne Wild, John Wilson, W. M. Wood-Vasey, Dominika Wylezalek, Ting Xiao, Renbin Yan, Meng Yang, Jason E. Ybarra, Christophe Yèche, Nadia Zakamska, Olga Zamora, Pauline Zarrouk, Gail Zasowski, Kai Zhang, Gong-Bo Zhao, Zheng Zheng, Zhi-Min Zhou, Guangtun B. Zhu, Manuela Zoccali, Hu Zou

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratio in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially-resolved spectroscopy for thousands of nearby galaxies (median redshift of z = 0. Read More

Al2O3 is a potential dielectric material for metal-oxide-semiconductor (MOS) devices. Al2O3 films deposited on semiconductors usually exhibit amorphous due to lattice mismatch. Compared to two-dimensional graphene, MoS2 is a typical semiconductor, therefore, it has more extensive application. Read More

Given a large number of low-level heterogeneous categorical alerts from an anomaly detection system, how to characterize complex relationships between different alerts, filter out false positives, and deliver trustworthy rankings and suggestions to end users? This problem is motivated by and generalized from applications in enterprise security and attack scenario reconstruction. While existing techniques focus on either reconstructing abnormal scenarios or filtering out false positive alerts, it can be more advantageous to consider the two perspectives simultaneously in order to improve detection accuracy and better understand anomaly behaviors. In this paper, we propose CAR, a collaborative alerts ranking framework that exploits both temporal and content correlations from heterogeneous categorical alerts. Read More

Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low H\alpha\ surface brightness regions display enhanced [SII]/H\alpha, [NII]/H\alpha, [OII]/H\beta, and [OI]/H\alpha. Read More

We present a study on the stellar age and metallicity distributions for 1105 galaxies using the STARLIGHT software on MaNGA integral field spectra. We derive age and metallicity gradients by fitting straight lines to the radial profiles, and explore their correlations with total stellar mass M*, NUV-r colour and environments, as identified by both the large scale structure (LSS) type and the local density. We find that the mean age and metallicity gradients are close to zero but slightly negative, which is consistent with the inside-out formation scenario. Read More

Inhomogeneous electron state and pseudogap have been widely observed in underdoped high temperature superconducting (HTSC) cuprates and some other strongly correlated materials. These phenomena are believed to be the characteristics of doped Mott insulators and have not yet been detected in other materials. Here, by using scanning tunneling microscopy (STM) and spectroscopy (STS), we demonstrate the electronic inhomogeneity at low energies and the pseudogap phenomenon in a conventional charge density wave (CDW) material 1T-TiSe2, with light doping by native defects. Read More

We study the problem of nonparametric dependence detection when no assumption is made about the joint distribution. We approach this problem by introducing the new concept of binary expansion statistics (BEStat), which examines dependence through a filtration induced by marginal binary expansions. In particular, we propose the binary expansion testing (BET) framework to test independence up to certain depth in the binary expansions. Read More

2016Oct
Authors: Kai Zhang1, Lei Hao2
Affiliations: 1Shanghai Astronomical Observatory, University of Kentucky, 2Shanghai Astronomical Observatory

We propose a new diagram, the Kinematic-Excitation diagram (KEx diagram), which uses the [OIII]/H\beta\ line ratio and the [OIII]5007 emission line width (\sigma_{[OIII]}) to diagnose the ionization source and physical properties of the Active Galactic Nuclei (AGNs) and the star-forming galaxies (SFGs). The KEx diagram is a suitable tool to classify emission-line galaxies (ELGs) at intermediate redshift because it uses only the [OIII]5007 and H\beta\ emission lines. We use the SDSS DR7 main galaxy sample and the Baldwin-Phillips-Terlevich (BPT) diagnostic to calibrate the diagram at low redshift. Read More

In this paper, we demonstrate that a consumer's marginal system impact is only determined by their demand profile rather than their demand level. Demand profile clustering is identical to cluster consumers according to their marginal impacts on system costs. A profile-based uniform-rate price is economically efficient as real-time pricing. Read More

The average star formation rate (SFR) in galaxies has been declining since redshift of 2. A fraction of galaxies quench and become quiescent. We constrain two key properties of the quenching process: the quenching time scale and the quenching rate among galaxies. Read More

The nature of warm, ionized gas outside of galaxies may illuminate several key galaxy evolutionary processes. A serendipitous observation by the MaNGA survey has revealed a large, asymmetric H$\alpha$ complex with no optical counterpart that extends $\approx8"$ ($\approx6.3$ kpc) beyond the effective radius of a dusty, starbursting galaxy. Read More

Anomaly detection plays an important role in modern data-driven security applications, such as detecting suspicious access to a socket from a process. In many cases, such events can be described as a collection of categorical values that are considered as entities of different types, which we call heterogeneous categorical events. Due to the lack of intrinsic distance measures among entities, and the exponentially large event space, most existing work relies heavily on heuristics to calculate abnormal scores for events. Read More

Discriminative model learning for image denoising has been recently attracting considerable attentions due to its favorable denoising performance. In this paper, we take one step forward by investigating the construction of feed-forward denoising convolutional neural networks (DnCNNs) to embrace the progress in very deep architecture, learning algorithm, and regularization method into image denoising. Specifically, residual learning and batch normalization are utilized to speed up the training process as well as boost the denoising performance. Read More

Intrusion detection system (IDS) is an important part of enterprise security system architecture. In particular, anomaly-based IDS has been widely applied to detect abnormal process behaviors that deviate from the majority. However, such abnormal behavior usually consists of a series of low-level heterogeneous events. Read More

2016Aug
Authors: SDSS Collaboration, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragon-Salamanca, Maria Argudo-Fernandez, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Beatriz Barbuy, Kat Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Sarbani Basu, Dominic Bates, Giuseppina Battaglia, Falk Baumgarten, Julien Baur, Julian Bautista, Timothy C. Beers, Francesco Belfiore, Matthew Bershady, Sara Bertran de Lis, Jonathan C. Bird, Dmitry Bizyaev, Guillermo A. Blanc, Michael Blanton, Michael Blomqvist, Adam S. Bolton, J. Borissova, Jo Bovy, William Nielsen Brandt, Jonathan Brinkmann, Joel R. Brownstein, Kevin Bundy, Etienne Burtin, Nicolas G. Busca, Hugo Orlando Camacho Chavez, M. Cano Diaz, Michele Cappellari, Ricardo Carrera, Yanping Chen, Brian Cherinka, Edmond Cheung, Cristina Chiappini, Drew Chojnowski, Chia-Hsun Chuang, Haeun Chung, Rafael Fernando Cirolini, Nicolas Clerc, Roger E. Cohen, Julia M. Comerford, Johan Comparat, Marie-Claude Cousinou, Kevin Covey, Jeffrey D. Crane, Rupert Croft, Katia Cunha, Luiz da Costa, Gabriele da Silva Ilha, Jeremy Darling, James W. Davidson Jr., Kyle Dawson, Nathan De Lee, Axel de la Macorra, Sylvain de la Torre, Alice Deconto Machado, Timothee Delubac, Aleksandar M. Diamond-Stanic, John Donor, Juan Jose Downes, Niv Drory, Helion du Mas des Bourboux, Cheng Du, Tom Dwelly, Garrett Ebelke, Arthur Eigenbrot, Daniel J. Eisenstein, Yvonne P. Elsworth, Eric Emsellem, Michael Eracleous, Stephanie Escoffier, Michael L. Evans, Jesus Falcon-Barroso, Xiaohui Fan, Ginevra Favole, Emma Fernandez-Alvar, J. G. Fernandez-Trincado, Diane Feuillet, Scott W. Fleming, Andreu Font-Ribera, Gordon Freischlad, Peter Frinchaboy, Hai Fu, Yang Gao, D. A. Garcia-Hernandez, Ana E. Garcia Perez, Rafael A. Garcia, R. Garcia-Dias, Patrick Gaulme, Junqiang Ge, Douglas Geisler, Hector Gil Marin, Bruce Gillespie, Leo Girardi, Daniel Goddard, Yilen Gomez Maqueo Chew, Violeta Gonzalez-Perez, Kathleen Grabowski, Paul Green, Catherine J. Grier, Thomas Grier, Hong Guo, Julien Guy, Alex Hagen, Matt Hall, Paul Harding, R. E. Harley, Sten Hasselquist, Suzanne Hawley, Christian R. Hayes, Fred Hearty, Saskia Hekker, Hector Hernandez Toledo, Shirley Ho, David W. Hogg, Kelly Holley-Bockelmann, Jon A. Holtzman, Parker H. Holzer, Jian Hu, Daniel Huber, Timothy Alan Hutchinson, Ho Seong Hwang, Hector J. Ibarra-Medel, Inese I. Ivans, KeShawn Ivory, Kurt Jaehnig, Trey W. Jensen, Jennifer A. Johnson, Amy Jones, Eric Jullo, T. Kallinger, Karen Kinemuchi, David Kirkby, Mark Klaene, Jean-Paul Kneib, Juna A. Kollmeier, Ivan Lacerna, Richard R. Lane, Dustin Lang, Pierre Laurent, David R. Law, Jean-Marc Le Goff, Alexie Leauthaud, Cheng Li, Ran Li, Chen Li, Niu Li, Fu-Heng Liang, Yu Liang, Marcos Lima, Lihwai Lin, Lin Lin, Yen-Ting Lin, Dan Long, Sara Lucatello, Nicholas MacDonald, Chelsea L. MacLeod, J. Ted Mackereth, Suvrath Mahadevan, Marcio Antonio-Geimba Maia, Roberto Maiolino, Steven R. Majewski, Olena Malanushenko, Nicolas Dullius Mallmann, Arturo Manchado, Claudia Maraston, Rui Marques-Chaves, Inma Martinez Valpuesta, Karen L. Masters, Savita Mathur, Ian D. McGreer, Andrea Merloni, Michael R. Merrifield, Szabolcs Meszaros, Andres Meza, Andrea Miglio, Ivan Minchev, Karan Molaverdikhani, Antonio D. Montero-Dorta, Benoit Mosser, Demitri Muna, Adam Myers, Preethi Nair, Kirpal Nandra, Melissa Ness, Jeffrey A. Newman, Robert C. Nichol, David L. Nidever, Christian Nitschelm, Julia O'Connell, Audrey Oravetz, Nelson Padilla, Nathalie Palanque-Delabrouille, Kaike Pan, John Parejko, Isabelle Paris, John A. Peacock, Sebastien Peirani, Marcos Pellejero-Ibanez, Samantha Penny, Will J. Percival, Jeffrey W. Percival, Ismael Perez-Fournon, Patrick Petitjean, Matthew Pieri, Marc H. Pinsonneault, Alice Pisani, Francisco Prada, Abhishek Prakash, Natalie Price-Jones, M. Jordan Raddick, Mubdi Rahman, Anand Raichoor, Sandro Barboza Rembold, A. M. Reyna, James Rich, Hannah Richstein, Jethro Ridl, Rogerio Riffel, Rogemar A. Riffel, Hans-Walter Rix, Annie C. Robin, Constance M. Rockosi, Sergio Rodriguez-Torres, Thaise S. Rodrigues, Natalie Roe, A. Roman Lopes, Carlos Roman-Zuniga, Ashley J. Ross, Graziano Rossi, John Ruan, Rossana Ruggeri, Jessie C. Runnoe, Salvador Salazar-Albornoz, Mara Salvato, Ariel G. Sanchez, Sebastian F. Sanchez, Jose R. Sanchez-Gallego, Basilio Xavier Santiago, Ricardo Schiavon, Jaderson S. Schimoia, Eddie Schlafly, David J. Schlegel, Donald P. Schneider, Ralph Schoenrich, Mathias Schultheis, Axel Schwope, Hee-Jong Seo, Aldo Serenelli, Branimir Sesar, Zhengyi Shao, Matthew Shetrone, Michael Shull, Victor Silva Aguirre, M. F. Skrutskie, Anže Slosar, Michael Smith, Verne V. Smith, Jennifer Sobeck, Garrett Somers, Diogo Souto, David V. Stark, Keivan G. Stassun, Matthias Steinmetz, Dennis Stello, Thaisa Storchi Bergmann, Michael A. Strauss, Alina Streblyanska, Guy S. Stringfellow, Genaro Suarez, Jing Sun, Manuchehr Taghizadeh-Popp, Baitian Tang, Charling Tao, Jamie Tayar, Mita Tembe, Daniel Thomas, Jeremy Tinker, Rita Tojeiro, Christy Tremonti, Nicholas Troup, Jonathan R. Trump, Eduardo Unda-Sanzana, O. Valenzuela, Remco van den Bosch, Mariana Vargas-Magana, Jose Alberto Vazquez, Sandro Villanova, M. Vivek, Nicole Vogt, David Wake, Rene Walterbos, Yuting Wang, Enci Wang, Benjamin Alan Weaver, Anne-Marie Weijmans, David H. Weinberg, Kyle B. Westfall, David G. Whelan, Eric Wilcots, Vivienne Wild, Rob A. Williams, John Wilson, W. M. Wood-Vasey, Dominika Wylezalek, Ting Xiao, Renbin Yan, Meng Yang, Jason E. Ybarra, Christophe Yeche, Fang-Ting Yuan, Nadia Zakamska, Olga Zamora, Gail Zasowski, Kai Zhang, Cheng Zhao, Gong-Bo Zhao, Zheng Zheng, Zheng Zheng, Zhi-Min Zhou, Guangtun Zhu, Joel C. Zinn, Hu Zou

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2, MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. Read More

The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy (IFS) for 10K nearby galaxies at a spectral resolution of R~2000 from 3,622-10,354A. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. Read More

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an optical fiber-bundle integral-field unit (IFU) spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). With a spectral coverage of 3622 - 10,354 Angstroms and an average footprint of ~ 500 arcsec^2 per IFU the scientific data products derived from MaNGA will permit exploration of the internal structure of a statistically large sample of 10,000 low redshift galaxies in unprecedented detail. Comprising 174 individually pluggable science and calibration IFUs with a near-constant data stream, MaNGA is expected to obtain ~ 100 million raw-frame spectra and ~ 10 million reduced galaxy spectra over the six-year lifetime of the survey. Read More

Matrix sketching is aimed at finding close approximations of a matrix by factors of much smaller dimensions, which has important applications in optimization and machine learning. Given a matrix A of size m by n, state-of-the-art randomized algorithms take O(m * n) time and space to obtain its low-rank decomposition. Although quite useful, the need to store or manipulate the entire matrix makes it a computational bottleneck for truly large and dense inputs. Read More

We study in this paper a dilute gas in a gravitational field and present a relation of the molecular distribution function with respect to position and velocity. The relation is obtained from the principle of detailed balance and can be used to study temperature distribution and density distribution. Read More

Amorphous solids, such as metallic, polymeric, and colloidal glasses, display complex spatiotemporal response to applied deformations. In contrast to crystalline solids, during loading, amorphous solids exhibit a smooth crossover from elastic response to plastic flow. In this study, we investigate the mechanical response of binary Lennard-Jones glasses to athermal, quasistatic pure shear as a function of the cooling rate used to prepare them. Read More

Heteroepitaxial structures based on Bi$_{2}$Te$_{3}$-type topological insulators (TIs) exhibit exotic quantum phenomena. For optimal characterization of these phenomena, it is desirable to control the interface structure during film growth on such TIs. In this process, adatom mobility is a key factor. Read More

Surface reactivity is important in modifying the physical and chemical properties of surface sensitive materials, such as the topological insulators (TIs). Even though many studies addressing the reactivity of TIs towards external gases have been reported, it is still under heavy debate whether and how the topological insulators react with H$_2$O. Here, we employ scanning tunneling microscopy (STM) to directly probe the surface reaction of Bi$_2$Te$_3$ towards H$_2$O. Read More

We clarify the confusion in the expression of the static structure factor S(k) in the study of condensed matters and discuss its explicit form that can be directly used in calculations and computer simulations. Read More

Quiescent galaxies with little or no ongoing star formation dominate the galaxy population above $M_{*}\sim 2 \times 10^{10}~M_{\odot}$, where their numbers have increased by a factor of $\sim25$ since $z\sim2$. Once star formation is initially shut down, perhaps during the quasar phase of rapid accretion onto a supermassive black hole, an unknown mechanism must remove or heat subsequently accreted gas from stellar mass loss or mergers that would otherwise cool to form stars. Energy output from a black hole accreting at a low rate has been proposed, but observational evidence for this in the form of expanding hot gas shells is indirect and limited to radio galaxies at the centers of clusters, which are too rare to explain the vast majority of the quiescent population. Read More

Tensor factorization is a powerful tool to analyse multi-way data. Compared with traditional multi-linear methods, nonlinear tensor factorization models are capable of capturing more complex relationships in the data. However, they are computationally expensive and may suffer severe learning bias in case of extreme data sparsity. Read More

Majorana fermion (MF) whose antiparticle is itself has been predicted in condensed matter systems. Signatures of the MFs have been reported as zero energy modes in various systems. More definitive evidences are highly desired to verify the existence of the MF. Read More

We report an atomic-scale characterization of ZrTe$_5$ by using scanning tunneling microscopy. We observe a bulk bandgap of ~80 meV with topological edge states at the step edge, and thus demonstrate ZrTe$_5$ is a two dimensional topological insulator. It is also found that an applied magnetic field induces energetic splitting and spatial separation of the topological edge states, which can be attributed to a strong link between the topological edge states and bulk topology. Read More

Generalized derivations, quasiderivations and quasicentroid of $3$-algebras are introduced, and basic relations between them are studied. Structures of quasiderivations and quasicentroid of $3$-Lie algebras, which contains a maximal diagonalized tours, are systematically investigated. The main results are: for all $3$-Lie algebra $A$, 1) the generalized derivation algebra $GDer(A)$ is the sum of quasiderivation algebra $QDer(A)$ and quasicentroid $Q\Gamma(A)$; 2) quasiderivations of $A$ can be embedded as derivations in a larger algebra; 3) quasiderivation algebra $QDer(A)$ normalizer quasicentroid, that is, $[QDer(A), Q\Gamma(A)]\subseteq Q\Gamma(A)$; 4) if $A$ contains a maximal diagonalized tours $T$, then $QDer(A)$ and $Q\Gamma(A)$ are diagonalized $T$-modules, that is, as $T$-modules, $(T, T)$ semi-simplely acts on $QDer(A)$ and $Q\Gamma(A)$, respectively. Read More

Electron transport properties of a topological insulator Bi$_2$Se$_3$ thin film are studied in Hall-bar geometry. The film with a thickness of 10 nm is grown by van der Waals epitaxy on fluorophlogopite mica and Hall-bar devices are fabricated from the as-grown film directly on the mica substrate. Weak antilocalization and electron-electron interaction effects are observed and analyzed at low temperatures. Read More

The bivariate normal density with unit variance and correlation $\rho$ is well-known. We show that by integrating out $\rho$, the result is a function of the maximum norm. The Bayesian interpretation of this result is that if we put a uniform prior over $\rho$, then the marginal bivariate density depends only on the maximal magnitude of the variables. Read More

We study the spherical cap packing problem with a probabilistic approach. Such probabilistic considerations result in an asymptotic sharp universal uniform bound on the maximal inner product between any set of unit vectors and a stochastically independent uniformly distributed unit vector. When the set of unit vectors are themselves independently uniformly distributed, we further develop the extreme value distribution limit of the maximal inner product, which characterizes its uncertainty around the bound. Read More

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV (SDSS-IV), is an integral-field spectroscopic (IFS) survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2 arcsec fibers to obtain resolved spectroscopy over a wide wavelength range of 3,600-10,300A. To map the internal variations within each galaxy, we need to perform accurate {\it spectral surface photometry}, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. Read More

We consider inference for the parameters of a linear model when the covariates are random and the relationship between response and covariates is possibly non-linear. Conventional inference methods such as z-intervals perform poorly in these cases. We propose a double bootstrap-based calibrated percentile method, perc-cal, as a general-purpose CI method which performs very well relative to alternative methods in challenging situations such as these. Read More

Periodic microphases universally emerge in systems for which short-range inter-particle attraction is frustrated by long-range repulsion. The morphological richness of these phases makes them desirable material targets, but our relatively coarse understanding of even simple models limits our grasp of their assembly. We report here the solution of the equilibrium phase behavior of a microscopic microphase former through specialized Monte Carlo simulations. Read More

Given data obtained under two sampling conditions, it is often of interest to identify variables that behave differently in one condition than in the other. We introduce a method for differential analysis of second-order behavior called Differential Correlation Mining (DCM). The DCM method identifies differentially correlated sets of variables, with the property that the average pairwise correlation between variables in a set is higher under one sample condition than the other. Read More

When a liquid is cooled well below its melting temperature at a rate that exceeds the critical cooling rate $R_c$, the crystalline state is bypassed and an amorphous glassy state forms instead. $R_c$ (or the corresponding critical casting thickness $d_c$) characterizes the glass-forming ability (GFA) of each material. While silica is an excellent glass-former with small $R_c<10^{-2}$ K/s, pure metals and most alloys are poor glass-formers with large $R_c>10^{10}$ K/s. Read More

We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using \textit{in situ} X-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, $\Delta\chi$, that drives alignment, and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding $\Delta\chi\approx 2\times10^{-8}$. Read More

We systematically study chromium arsenide in various crystal structures in order to investigate the structural, magnetic and electronic properties for real applications. The calculations are performed within the density functional framework using the projected augmented plane wave method as employed in VASP code. Using the generalized gradient approximation (GGA) for exchange correlation energy functional, we have calculated the lattice parameters, bulk modulus and cohesive energy. Read More

Graphene is a rising star in nonlinear optics due to its saturable absorption and giant Kerr nonlinearity, these properties are useful in digital optics based on optical nonlinear devices. However, practical applications require large optical nonlinearities and these are inherently limited by the interaction length of atomically thin graphene. Here, we demonstrate optical bistability in a Fabry Perot cavity containing monolayer and bilayer graphene which have been restructured to form nanobubbles. Read More

MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is an integral-field spectroscopic survey of 10,000 nearby galaxies that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). MaNGA's 17 pluggable optical fiber-bundle integral field units (IFUs) are deployed across a 3 deg field, they yield spectral coverage 3600-10,300 Ang at a typical resolution R ~ 2000, and sample the sky with 2" diameter fiber apertures with a total bundle fill factor of 56%. Observing over such a large field and range of wavelengths is particularly challenging for obtaining uniform and integral spatial coverage and resolution at all wavelengths and across each entire fiber array. Read More

Dual-energy X-ray absorptiometry (DEXA) has been widely applied to measure bone mineral density (BMD) and soft-tissue composition of human body. However, the use of DEXA is greatly limited for low-Z materials such as soft tissues due to their weak absorption. While X-ray phase-contrast imaging (XPCI) shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. Read More

A new simple mechanism due to cold electron flow to produce strong magnetic field is proposed. A 600-T strong magnetic field is generated in the free space at the laser intensity of 5.7x10^15 Wcm^-2. Read More

MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-year SDSS-IV survey that will obtain resolved spectroscopy from 3600 $\AA$ to 10300 $\AA$ for a representative sample of over 10,000 nearby galaxies. In this paper, we derive spatially resolved stellar population properties and radial gradients by performing full spectral fitting of observed galaxy spectra from P-MaNGA, a prototype of the MaNGA instrument. These data include spectra for eighteen galaxies, covering a large range of morphological type. Read More