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Articles 3031 - 3060 of 16838

Full-Text Articles in Physical Sciences and Mathematics

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston Nov 2017

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston

Lora Billings

The goal of this paper is to motivate the need and lay the foundation for the analysis of stochastic epidemiological models with seasonal forcing.We consider stochastic SIS and SIR epidemic models, where the internal noise is due to the random interactions of individuals in the population. We provide an overview of the general theoretic framework that allows one to understand noise-induced rare events, such as spontaneous disease extinction. Although there are many paths to extinction, there is one path termed the optimal path that is probabilistically most likely to occur. By extending the theory, we have identified the quasi-stationary solutions …


Variational Bayes Estimation Of Discrete-Margined Copula Models With Application To Ime Series, Ruben Loaiza-Maya, Michael S. Smith Nov 2017

Variational Bayes Estimation Of Discrete-Margined Copula Models With Application To Ime Series, Ruben Loaiza-Maya, Michael S. Smith

Michael Stanley Smith

We propose a new variational Bayes estimator for high-dimensional copulas with discrete, or a combination of discrete and continuous, margins. The method is based on a variational approximation to a tractable augmented posterior, and is faster than previous likelihood-based approaches. We use it to estimate drawable vine copulas for univariate and multivariate Markov ordinal and mixed time series. These have dimension $rT$, where $T$ is the number of observations and $r$ is the number of series, and are difficult to estimate using previous methods. 
The vine pair-copulas are carefully selected to allow for heteroskedasticity, which is a feature of most ordinal …


Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston Nov 2017

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston

Eric Forgoston

The goal of this paper is to motivate the need and lay the foundation for the analysis of stochastic epidemiological models with seasonal forcing.We consider stochastic SIS and SIR epidemic models, where the internal noise is due to the random interactions of individuals in the population. We provide an overview of the general theoretic framework that allows one to understand noise-induced rare events, such as spontaneous disease extinction. Although there are many paths to extinction, there is one path termed the optimal path that is probabilistically most likely to occur. By extending the theory, we have identified the quasi-stationary solutions …


Importing Democracy: Promoting Participatory Decision Making In Russian Forest Communities, Maria Tysiachniouk, Errol E. Meidinger Nov 2017

Importing Democracy: Promoting Participatory Decision Making In Russian Forest Communities, Maria Tysiachniouk, Errol E. Meidinger

Errol Meidinger

Published in Environmental Democracy Facing Uncertainty, Cécilia Claeys & Marie Jacqué, eds.

This paper describes how the World Wildlife Fund for Nature (WWF) jump-started democratic institutions in Russian rural communities to create a basis for social, environmental, and economic modernization within the Russian forestry sector. In Russia’s post-soviet markets and institutions, a host of multinational companies and large transnational environmental organizations sought to promote the restructuring of Russia’s legal and economic infrastructure and active subsidiaries in Russia. In order for modern forestry approaches to be imported, management practices that had developed in the West needed to be adapted to Russia’s …


Sustainable East Africa Research In Community Health (Search): A Community Cluster Randomized Study Of Hiv "Test And Treat" Using Multi-Disease Approach In Rural Uganda And Kenya, Laura Balzer, Diane V. Havlir, Joshua Schwab, Mark J. Van Der Laan, Maya Petersen Nov 2017

Sustainable East Africa Research In Community Health (Search): A Community Cluster Randomized Study Of Hiv "Test And Treat" Using Multi-Disease Approach In Rural Uganda And Kenya, Laura Balzer, Diane V. Havlir, Joshua Schwab, Mark J. Van Der Laan, Maya Petersen

Laura B. Balzer

This document provides the analytic plan for evaluating adult HIV incidence, health, and implementation outcomes for the first phase of the SEARCH Study. Locked: November 27, 2017. Embargoed until July 25, 2018.


Toward A Synthesis Of Conservation And Animal Welfare Science, David Fraser Nov 2017

Toward A Synthesis Of Conservation And Animal Welfare Science, David Fraser

David Fraser, PhD

Conservation biology and animal welfare science are multidisciplinary fields of research that address social concerns about animals. Conservation biology focuses on wild animals, works at the level of populations, ecological systems and genetic types, and deals with threats to biodiversity and ecological integrity. Animal welfare science typically focuses on captive (often domestic) animals, works at the level of individuals and groups, and deals with threats to the animals’ health and quality of life. However, there are many areas of existing or potential overlap: (i) many real-life problems, such as environmental contamination, urban development and transportation, create problems for animals that …


Rating Harms To Wildlife: A Survey Showing Convergence Between Conservation And Animal Welfare Views, S. Dubois, D. Fraser Nov 2017

Rating Harms To Wildlife: A Survey Showing Convergence Between Conservation And Animal Welfare Views, S. Dubois, D. Fraser

David Fraser, PhD

Human activities may cause conservation concerns when animal populations or ecosystems are harmed and animal welfare concerns when individuals are harmed. In general, people are concerned with one or the other, as the concepts may be regarded as separate or even at odds. An online purposive survey of 339 British Columbians explored differences between groups that varied by gender, residency, wildlife engagement level and value orientation (conservation-oriented or animal welfare-oriented), to see how they rated the level of harm to wildlife caused by different human activities. Women, urban residents, those with low wildlife engagement, and welfare-orientated participants generally scored activities …


Hypervolatiles In A Jupiter-Family Comet: Observations Of 45p/Honda–Mrkos–Pajdušáková Using Ishell At The Nasa-Irtf, Michael A. Disanti, Boncho P. Bonev, Neil Dello Russo, Ronald J. Vervack, Erika L. Gibb, Nathan X. Roth, Adam J. Mckay, Hideyo Kawakita, Lori M. Feaga, Harold A. Weaver Nov 2017

Hypervolatiles In A Jupiter-Family Comet: Observations Of 45p/Honda–Mrkos–Pajdušáková Using Ishell At The Nasa-Irtf, Michael A. Disanti, Boncho P. Bonev, Neil Dello Russo, Ronald J. Vervack, Erika L. Gibb, Nathan X. Roth, Adam J. Mckay, Hideyo Kawakita, Lori M. Feaga, Harold A. Weaver

Erika Gibb

We used the new high spectral resolution cross-dispersed facility spectrograph, iSHELL, at the NASA Infrared Telescope Facility on Maunakea, HI, to observe Jupiter-family comet (JFC) 45P/Honda–Mrkos–Pajdušáková. We report water production rates, as well as production rates and abundance ratios relative to H2O, for eight trace parent molecules (native ices), CO, CH4, H2CO, CH3OH, HCN, NH3, C2H2, and C2H6, on 2 days spanning UT 2017 January 6/7 and 7/8, shortly following perihelion. Trace species were measured simultaneously with H2O and/or OH prompt emission, a proxy for H2O production, thereby providing a robust and consistent means of establishing the native ice composition …


Interpreting Main Effect With Moderation ‐‐ A View Through The Prism Of Causal Dissection, Xinshu Zhao Nov 2017

Interpreting Main Effect With Moderation ‐‐ A View Through The Prism Of Causal Dissection, Xinshu Zhao

Professor Xinshu ZHAO

In many disciplines of social sciences, it’s widely believed that main effect is uninterpretable when moderation exists. This research starts with an observation that four popular mode of data analysis, mediation, moderation,
curvilinearity, and confounding, all attempt to dissect an XY simple linear effect into various components.
Through this prism of theory, this research uncovers an important interpretation for the main effect, with or without moderation. The main effect, according to the theory of causal dissection, is a combination of two effects, namely on‐group effect and in‐group effect, while the in‐group effect is a weighted average of the XY effects …


A Conceptual Framework For Sustainable Water Management: The Case Of The Piracicaba River Basin, Brazil [Abstract], Amós Nascimento Nov 2017

A Conceptual Framework For Sustainable Water Management: The Case Of The Piracicaba River Basin, Brazil [Abstract], Amós Nascimento

Amós Nascimento

2 pages.


On Osgood's Criterion For Classical Wave Equations And Nonlinear Shallow Water Wave Equations, Timothy Smith, Greg Spradlin Nov 2017

On Osgood's Criterion For Classical Wave Equations And Nonlinear Shallow Water Wave Equations, Timothy Smith, Greg Spradlin

Timothy Smith

The problem on classical solutions for the wave equation and the BBM equation is considered. The equations are considered with a forcing term and sufficient conditions of solvability, existence and uniqueness are established.


Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepanczyk, M. Zanolin, Et Al. Nov 2017

Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepanczyk, M. Zanolin, Et Al.

Michele Zanolin

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5 σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 …


Search For Transient Gravitational Waves In Coincidence With Short-Duration Radio Transients During 2007-2013, B. P. Abbott, K. Gill, B. Hughey, D. Stiles, M. Szczepańczyk, M. Zanolin, Et Al. Nov 2017

Search For Transient Gravitational Waves In Coincidence With Short-Duration Radio Transients During 2007-2013, B. P. Abbott, K. Gill, B. Hughey, D. Stiles, M. Szczepańczyk, M. Zanolin, Et Al.

Michele Zanolin

We present an archival search for transient gravitational-wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, …


Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al. Nov 2017

Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al.

Michele Zanolin

The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches for short-duration gravitational-wave transients. These searches identify time-correlated transients in multiple detectors with minimal assumptions about the signal morphology, allowing them to be sensitive to gravitational waves emitted by a wide range of sources including binary black hole mergers. Over the observational period from September 12 to October 20, 2015, these transient searches were sensitive to binary black hole mergers similar to GW150914 to an average distance of ∼600  Mpc. In this paper, we describe the analyses that first detected GW150914 as well as the parameter estimation …


Nilpotent Linear Transformations And The Solvability Of Power-Associative Nilalgebras, Ivan Correa, Irvin R. Hentzel, Pedro Pablo Julca, Luiz Antonio Peresi Nov 2017

Nilpotent Linear Transformations And The Solvability Of Power-Associative Nilalgebras, Ivan Correa, Irvin R. Hentzel, Pedro Pablo Julca, Luiz Antonio Peresi

Irvin Roy Hentzel

We prove some results about nilpotent linear transformations. As an application we solve some cases of Albert’s problem on the solvability of nilalgebras. More precisely, we prove the following results: commutative power-associative nilalgebras of dimension n and nilindex n − 1 or n − 2 are solvable; commutative power-associative nilalgebras of dimension 7 are solvable.


Nuclear Elements Of Degree 6 In The Free Alternative Algebra, Irvin R. Hentzel, L. A. Peresi Nov 2017

Nuclear Elements Of Degree 6 In The Free Alternative Algebra, Irvin R. Hentzel, L. A. Peresi

Irvin Roy Hentzel

We construct five new elements of degree 6 in the nucleus of the free alternative algebra. We use the representation theory of the symmetric group to locate the elements. We use the computer algebra system ALBERT and an extension of ALBERT to express the elements in compact form and to show that these new elements are not a consequence of the known degree-5 elements in the nucleus. We prove that these five new elements and four known elements form a basis for the subspace of nuclear elements of degree 6. Our calculations are done using modular arithmetic to save memory …


Solvability Of Commutative Right-Nilalgebras Satisfying (B (Aa)) A= B ((Aa) A), Ivan Correa, Alicia Labra, Irvin R. Hentzel Nov 2017

Solvability Of Commutative Right-Nilalgebras Satisfying (B (Aa)) A= B ((Aa) A), Ivan Correa, Alicia Labra, Irvin R. Hentzel

Irvin Roy Hentzel

We study commutative right-nilalgebras of right-nilindex four satisfying the identity (b(aa))a = b((aa)a). Our main result is that these algebras are solvable and not necessarily nilpotent. Our results require characteristic ≠ 2, 3, 5.


Invariant Nonassociative Algebra Structures On Irreducible Representations Of Simple Lie Algebras, Murray Bremner, Irvin R. Hentzel Nov 2017

Invariant Nonassociative Algebra Structures On Irreducible Representations Of Simple Lie Algebras, Murray Bremner, Irvin R. Hentzel

Irvin Roy Hentzel

An irreducible representation of a simple Lie algebra can be a direct summand of its own tensor square. In this case, the representation admits a nonassociative algebra structure which is invariant in the sense that the Lie algebra acts as derivations. We study this situation for the Lie algebra sl(2).


The Nucleus Of The Free Alternative Algebra, Irvin R. Hentzel, L. A. Peresi Nov 2017

The Nucleus Of The Free Alternative Algebra, Irvin R. Hentzel, L. A. Peresi

Irvin Roy Hentzel

We use a computer procedure to determine a basis of the elements of degree 5 in the nucleus of the free alternative algebra. In order to save computer memory, we do our calculations over the field Z103. All calculations are made with multilinear identities. Our procedure is also valid for other characteristics and for determining nuclear elements of higher degree.


Rings With (A, B, C) = (A, C, B) And (A, [B, C]D) = 0: A Case Study Using Albert, Irvin R. Hentzel, D. P. Jacobs, Erwin Kleinfeld Nov 2017

Rings With (A, B, C) = (A, C, B) And (A, [B, C]D) = 0: A Case Study Using Albert, Irvin R. Hentzel, D. P. Jacobs, Erwin Kleinfeld

Irvin Roy Hentzel

Albert is an interactive computer system for building nonassociative algebras [2]. In this paper, we suggest certain techniques for using Albert that allow one to posit and test hypotheses effectively. This process provides a fast way to achieve new results, and interacts nicely with traditional methods. We demonstrate the methodology by proving that any semiprime ring, having characteristic ≠ 2, 3, and satisfying the identities (a, b, c) - (a, c, b) = (a, [b, c], d) = 0, is associative. This generalizes a recent result by Y. Paul [7].


A Variety Containing Jordan And Pseudo-Composition Algebras, Irvin R. Hentzel, Luiz Antonio Peresi Nov 2017

A Variety Containing Jordan And Pseudo-Composition Algebras, Irvin R. Hentzel, Luiz Antonio Peresi

Irvin Roy Hentzel

We consider 3-Jordan algebras, i.e., the nonassociative commutative algebras satisfying (x^3 y)x=x^3(yx). The variety of 3-Jordan algebras contains all Jordan algebras and all pseudo-composition algebras. We prove that a simple 3-Jordan algebra with idempotent is either a Jordan algebra or a pseudo-composition algebra.


Commutative Finitely Generated Algebras Satisfying ((Yx)X)X=0 Are Solvable, Ivan Correa, Irvin R. Hentzel Nov 2017

Commutative Finitely Generated Algebras Satisfying ((Yx)X)X=0 Are Solvable, Ivan Correa, Irvin R. Hentzel

Irvin Roy Hentzel

No abstract provided.


Identities Relating The Jordan Product And The Associator In The Free Nonassociative Algebra, Murray R. Bremner, Irvin R. Hentzel Nov 2017

Identities Relating The Jordan Product And The Associator In The Free Nonassociative Algebra, Murray R. Bremner, Irvin R. Hentzel

Irvin Roy Hentzel

We determine the identities of degree ≤ 6 satisfied by the symmetric (Jordan) product a○b = ab + ba and the associator [a,b,c] = (ab)c - a(bc) in every nonassociative algebra. In addition to the commutative identity a○b = b○a we obtain one new identity in degree 4 and another new identity in degree 5. We demonstrate the existence of further new identities in degree 6. These identities define a variety of binary-ternary algebras which generalizes the variety of Jordan algebras in the same way that Akivis algebras generalize Lie algebras.


Generalized Alternative And Malcev Algebras, Irvin R. Hentzel, H.F. Smith Nov 2017

Generalized Alternative And Malcev Algebras, Irvin R. Hentzel, H.F. Smith

Irvin Roy Hentzel

No abstract provided.


Generalized Right Alternative Rings, Irvin R. Hentzel Nov 2017

Generalized Right Alternative Rings, Irvin R. Hentzel

Irvin Roy Hentzel

We show that weakening the hypotheses of right alternative rings to the three identities (1) (ab,c,d) + (a,b,[c,d]) = a(b,c,d) + (a,c,d)b (2) (α,α,α) = 0 (3) ([a,b],b,b) = O for all α, b, c, d in the ring will not lead to any new simple rings. In fact, the ideal generated by each associator of the form (a, b, b) is a nilpotent ideal of index at most three. Our proofs require characteristic ^2 , ^3 .


Fast Change Of Basis In Algebras, Irvin R. Hentzel, David Pokrass Jacobs Nov 2017

Fast Change Of Basis In Algebras, Irvin R. Hentzel, David Pokrass Jacobs

Irvin Roy Hentzel

Given an n-dimensional algebraA represented by a basisB and structure constants, and given a transformation matrix for a new basisC., we wish to compute the structure constants forA relative to C. There is a straightforward way to solve this problem inO(n5) arithmetic operations. However given an O(nω) matrix multiplication algorithm, we show how to solve the problem in time O(nω+1). Using the method of Coppersmith and Winograd, this yields an algorithm ofO(n3.376).


Complexity And Unsolvability Properties Of Nilpotency, Irvin R. Hentzel, David Pokrass Jacobs Nov 2017

Complexity And Unsolvability Properties Of Nilpotency, Irvin R. Hentzel, David Pokrass Jacobs

Irvin Roy Hentzel

A nonassociative algebra is nilpotent if there is some n such that the product of any n elements, no matter how they are associated, is zero. Several related, but more general, notions are left nilpotency, solvability, local nilpotency, and nillity. First the complexity of several decision problems for these properties is examined. In finite-dimensional algebras over a finite field it is shown that solvability and nilpotency can be decided in polynomial time. Over Q, nilpotency can be decided in polynomial time, while the algorithm for testing solvability uses a polynomial number of arithmetic operations, but is not polynomial time. Also …


Idempotents In Plenary Train Algebras, Antonio Behn, Irvin R. Hentzel Nov 2017

Idempotents In Plenary Train Algebras, Antonio Behn, Irvin R. Hentzel

Irvin Roy Hentzel

In this paper we study plenary train algebras of arbitrary rank. We show that for most parameter choices of the train identity, the additional identity (x^2 -w(x)x)^2 =0 is satisfied. We also find sufficient conditions for A to have idempotents.


Left Centralizers On Rings That Are Not Semiprime, Irvin R. Hentzel, M.S. Tammam El-Sayiad Nov 2017

Left Centralizers On Rings That Are Not Semiprime, Irvin R. Hentzel, M.S. Tammam El-Sayiad

Irvin Roy Hentzel

A (left) centralizer for an associative ring R is an additive map satisfying T(xy) = T(x)y for all x, y in R. A (left) Jordan centralizer for an associative ring R is an additive map satisfying T(xy+yx) = T(x)y + T(y)x for all x, y in R. We characterize rings with a Jordan centralizer T. Such rings have a T invariant ideal I, T is a centralizer on R/I, and I is the union of an ascending chain of nilpotent …


Existence Results For Multivalued Operators Of Monotone Type In Reflexive Banach Spaces, Dhruba Adhikari Nov 2017

Existence Results For Multivalued Operators Of Monotone Type In Reflexive Banach Spaces, Dhruba Adhikari

Dhruba Adhikari

No abstract provided.