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Articles 31 - 60 of 294

Full-Text Articles in Mathematics

Relaxed Wythoff Has All Beatty Solutions, Jon Kay, Geremías Polanco Jul 2022

Relaxed Wythoff Has All Beatty Solutions, Jon Kay, Geremías Polanco

Mathematics Sciences: Faculty Publications

We find conditions under which the P-positions of three subtraction games arise as pairs of complementary Beatty sequences. The first game is due to Fraenkel and the second is an extension of the first game to non-monotone settings. We show that the P-positions of the second game can be inferred from the recurrence of Fraenkel's paper if a certain inequality is satisfied. This inequality is shown to be necessary if the P-positions are known to be pairs of complementary Beatty sequences, and the family of irrationals for which this inequality holds is explicitly given. We highlight several games in the …


Neumann Problems For P-Harmonic Functions, And Induced Nonlocal Operators In Metric Measure Spaces, Luca Capogna, Josh Kline, Riikka Korte, Nageswari Shanmugalingam, Marie Snipes Apr 2022

Neumann Problems For P-Harmonic Functions, And Induced Nonlocal Operators In Metric Measure Spaces, Luca Capogna, Josh Kline, Riikka Korte, Nageswari Shanmugalingam, Marie Snipes

Mathematics Sciences: Faculty Publications

Following ideas of Caffarelli and Silvestre in [20], and using recent progress in hyperbolic fillings, we define fractional p-Laplacians (−∆p) θ with 0 < θ < 1 on any compact, doubling metric measure space (Z, d, ν), and prove existence, regularity and stability for the non-homogenous non-local equation (−∆p) θu = f. These results, in turn, rest on the new existence, global Hölder regularity and stability theorems that we prove for the Neumann problem for p-Laplacians ∆p, 1 < p < ∞, in bounded domains of measure metric spaces endowed with a doubling measure that supports a Poincaré inequality. Our work also includes as special cases much of the previous results by other authors in the Euclidean, Riemannian and Carnot group settings. Unlike other recent contributions in the metric measure spaces context, our work does not rely on the assumption that (Z, d, ν) supports a Poincaré inequality.


The Transition Matrix Between The Specht And ����3 Web Bases Is Unitriangular With Respect To Shadow Containment, Heather M. Russell, Julianna Tymoczko Mar 2022

The Transition Matrix Between The Specht And ����3 Web Bases Is Unitriangular With Respect To Shadow Containment, Heather M. Russell, Julianna Tymoczko

Mathematics Sciences: Faculty Publications

Webs are planar graphs with boundary that describe morphisms in a diagrammatic representation category for ����k ⁠. They are studied extensively by knot theorists because braiding maps provide a categorical way to express link diagrams in terms of webs, producing quantum invariants like the well-known Jones polynomial. One important question in representation theory is to identify the relationships between different bases; coefficients in the change-of-basis matrix often describe combinatorial, algebraic, or geometric quantities (e.g., Kazhdan–Lusztig polynomials). By ”flattening” the braiding maps, webs can also be viewed as the basis elements of a symmetric group representation. In this paper, we define …


Lipschitz Regularity For The Parabolic P-Laplacian In The Heisenberg Group, Luca Capogna, Giovanna Citti, Xiao Zhong Feb 2022

Lipschitz Regularity For The Parabolic P-Laplacian In The Heisenberg Group, Luca Capogna, Giovanna Citti, Xiao Zhong

Mathematics Sciences: Faculty Publications

In this paper we establish the local Lipschitz regularity of weak solutions of a certain class of quasilinear, degenerate parabolic equations in the Heisenberg group Hn , or more in general in contact subRiemannian manifolds. In particular we extend to the non-stationary setting.


Toward Permutation Bases In The Equivariant Cohomology Rings Of Regular Semisimple Hessenberg Varieties, Megumi Harada, Martha Precup, Julianna Tymoczko Jan 2022

Toward Permutation Bases In The Equivariant Cohomology Rings Of Regular Semisimple Hessenberg Varieties, Megumi Harada, Martha Precup, Julianna Tymoczko

Mathematics Sciences: Faculty Publications

Recent work of Shareshian and Wachs, Brosnan and Chow, and Guay-Paquet connects the wellknown Stanley–Stembridge conjecture in combinatorics to the dot action of the symmetric group Sn on the cohomology rings H∗ (Hess(S, h)) of regular semisimple Hessenberg varieties. In particular, in order to prove the Stanley–Stembridge conjecture, it suffices to construct (for any Hessenberg function h) a permutation basis of H∗ (Hess(S, h)) whose elements have stabilizers isomorphic to Young subgroups. In this manuscript we give several results which contribute toward this goal. Specifically, in some special cases, we give a new, purely combinatorial construction of classes …


Dihedral Linking Invariants, Patricia Cahn, Elise Catania, Sarangoo Chimgee, Olivia Del Guercio, Jack Kendrick Dec 2021

Dihedral Linking Invariants, Patricia Cahn, Elise Catania, Sarangoo Chimgee, Olivia Del Guercio, Jack Kendrick

Mathematics Sciences: Faculty Publications

A Fox p-colored knot K in S3 gives rise to a p-fold branched cover M of S3 along K. The pre-image of the knot K under the covering map is a p+1/2-component link L in M, and the set of pairwise linking numbers of the components of L is an invariant of K. This powerful invariant played a key role in the development of early knot tables, and appears in formulas for many other important knot and manifold invariants. We give an algorithm for computing this invariant for all odd p, generalizing an …


Distinct Circadian Assessments From Wearable Data Reveal Social Distancing Promoted Internal Desynchrony Between Circadian Markers, Yitong Huang, Caleb Mayer, Olivia J. Walch, Clark Bowman, Srijan Sen, Cathy Goldstein, Jonathan Tyler, Daniel B. Forger Nov 2021

Distinct Circadian Assessments From Wearable Data Reveal Social Distancing Promoted Internal Desynchrony Between Circadian Markers, Yitong Huang, Caleb Mayer, Olivia J. Walch, Clark Bowman, Srijan Sen, Cathy Goldstein, Jonathan Tyler, Daniel B. Forger

Mathematics Sciences: Faculty Publications

Mobile measures of human circadian rhythms (CR) are needed in the age of chronotherapy. Two wearable measures of CR have recently been validated: one that uses heart rate to extract circadian rhythms that originate in the sinoatrial node of the heart, and another that uses activity to predict the laboratory gold standard and central circadian pacemaker marker, dim light melatonin onset (DLMO). We first find that the heart rate markers of normal real-world individuals align with laboratory DLMO measurements when we account for heart rate phase error. Next, we expand upon previous work that has examined sleep patterns or chronotypes …


System Identification Through Lipschitz Regularized Deep Neural Networks, Elisa Negrini, Giovanna Citti, Luca Capogna Nov 2021

System Identification Through Lipschitz Regularized Deep Neural Networks, Elisa Negrini, Giovanna Citti, Luca Capogna

Mathematics Sciences: Faculty Publications

In this paper we use neural networks to learn governing equations from data. Specifically we reconstruct the right-hand side of a system of ODEs x˙(t)=f(t,x(t)) directly from observed uniformly time-sampled data using a neural network. In contrast with other neural network-based approaches to this problem, we add a Lipschitz regularization term to our loss function. In the synthetic examples we observed empirically that this regularization results in a smoother approximating function and better generalization properties when compared with non-regularized models, both on trajectory and non-trajectory data, especially in presence of noise. In contrast with sparse regression approaches, since neural networks …


A Neural Network Ensemble Approach To System Identification, Elisa Negrini, Giovanna Citti, Luca Capogna Oct 2021

A Neural Network Ensemble Approach To System Identification, Elisa Negrini, Giovanna Citti, Luca Capogna

Mathematics Sciences: Faculty Publications

We present a new algorithm for learning unknown governing equations from trajectory data, using and ensemble of neural networks. Given samples of solutions x(t) to an unknown dynamical system x˙(t) = f(t, x(t)), we approximate the function f using an ensemble of neural networks. We express the equation in integral form and use Euler method to predict the solution at every successive time step using at each iteration a different neural network as a prior for f. This procedure yields M-1 time-independent networks, where M is the number of time steps at which x(t) is observed. Finally, we obtain a …


Predicting Circadian Phase Across Populations: A Comparison Of Mathematical Models And Wearable Devices, Yitong Huang, Caleb Mayer, Philip Cheng, Alankrita Siddula, Helen J. Burgess, Christopher Drake, Cathy Goldstein, Olivia Walch, Daniel B. Forger, Daniel B. Forger Oct 2021

Predicting Circadian Phase Across Populations: A Comparison Of Mathematical Models And Wearable Devices, Yitong Huang, Caleb Mayer, Philip Cheng, Alankrita Siddula, Helen J. Burgess, Christopher Drake, Cathy Goldstein, Olivia Walch, Daniel B. Forger, Daniel B. Forger

Mathematics Sciences: Faculty Publications

From smart work scheduling to optimal drug timing, there is enormous potential in translating circadian rhythms research results for precision medicine in the real world. However, the pursuit of such effort requires the ability to accurately estimate circadian phase outside of the laboratory. One approach is to predict circadian phase noninvasively using light and activity measurements and mathematical models of the human circadian clock. Most mathematical models take light as an input and predict the effect of light on the human circadian system. However, consumer-grade wearables that are already owned by millions of individuals record activity instead of light, which …


Linking Numbers In Three-Manifolds, Patricia Cahn, Alexandra Kjuchukova Sep 2021

Linking Numbers In Three-Manifolds, Patricia Cahn, Alexandra Kjuchukova

Mathematics Sciences: Faculty Publications

Let M be a connected, closed, oriented three-manifold and K, L two rationally null-homologous oriented simple closed curves in M. We give an explicit algorithm for computing the linking number between K and L in terms of a presentation of M as an irregular dihedral three-fold cover of S3 branched along a knot α⊂ S3. Since every closed, oriented three-manifold admits such a presentation, our results apply to all (well-defined) linking numbers in all three-manifolds. Furthermore, ribbon obstructions for a knot α can be derived from dihedral covers of α. The linking numbers we compute are necessary for evaluating one …


A Method For Characterizing Daily Physiology From Widely Used Wearables, Clark Bowman, Yitong Huang, Olivia J. Walch, Yu Fang, Elena Frank, Jonathan Tyler, Caleb Mayer, Christopher Stockbridge, Cathy Goldstein, Srijan Sen, Daniel B. Forger Aug 2021

A Method For Characterizing Daily Physiology From Widely Used Wearables, Clark Bowman, Yitong Huang, Olivia J. Walch, Yu Fang, Elena Frank, Jonathan Tyler, Caleb Mayer, Christopher Stockbridge, Cathy Goldstein, Srijan Sen, Daniel B. Forger

Mathematics Sciences: Faculty Publications

Millions of wearable-device users record their heart rate (HR) and activity. We introduce a statistical method to extract and track six key physiological parameters from these data, including an underlying circadian rhythm in HR (CRHR), the direct effects of activity, and the effects of meals, posture, and stress through hormones like cortisol. We test our method on over 130,000 days of real-world data from medical interns on rotating shifts, showing that CRHR dynamics are distinct from those of sleep-wake or physical activity patterns and vary greatly among individuals. Our method also estimates a personalized phase-response curve of CRHR to activity …


Hessenberg Varieties Of Parabolic Type, Martha Precup, Julianna Tymoczko May 2021

Hessenberg Varieties Of Parabolic Type, Martha Precup, Julianna Tymoczko

Mathematics Sciences: Faculty Publications

This paper studies the geometry and combinatorics of three interrelated varieties: Springer fibers, Steinberg varieties, and parabolic Hessenberg varieties. We prove that each parabolic Hessenberg variety is the pullback of a Steinberg variety under the projection of the flag variety to an appropriate partial flag variety and we give three applications of this result. The first application constructs an explicit paving of all Steinberg varieties in Lie type A in terms of semistandard tableaux. As a result, we obtain an elementary proof of a theorem of Steinberg and Shimomura that the well-known Kostka numbers count the maximal-dimensional irreducible components of …


Representation Stability Of The Cohomology Of Springer Varieties And Some Combinatorial Consequences, Aba Mbirika, Julianna Tymoczko May 2021

Representation Stability Of The Cohomology Of Springer Varieties And Some Combinatorial Consequences, Aba Mbirika, Julianna Tymoczko

Mathematics Sciences: Faculty Publications

A sequence of Sn-representations { Vn} is said to be uniformly representation stable if the decomposition of Vn= ⨁ μcμ,nV(μ) n into irreducible representations is independent of n for each μ—that is, the multiplicities cμ,n are eventually independent of n for each μ. Church–Ellenberg–Farb proved that the cohomology of flag varieties (the so-called diagonal coinvariant algebra) is uniformly representation stable. We generalize their result from flag varieties to all Springer fibers. More precisely, we show that for any increasing subsequence of Young diagrams, the corresponding sequence of Springer representations form a graded co-FI-module of finite type (in the sense of …


Conformal Equivalence Of Visual Metrics In Pseudoconvex Domains, Luca Capogna, Enrico Le Donne Feb 2021

Conformal Equivalence Of Visual Metrics In Pseudoconvex Domains, Luca Capogna, Enrico Le Donne

Mathematics Sciences: Faculty Publications

We refine estimates introduced by Balogh and Bonk, to show that the boundary extensions of isometries between bounded, smooth strongly pseudoconvex domains in Cn are conformal with respect to the sub-Riemannian metric induced by the Levi form. As a corollary we obtain an alternative proof of a result of Fefferman on smooth extensions of biholomorphic mappings between bounded smooth pseudoconvex domains. The proofs are inspired by Mostow’s proof of his rigidity theorem and are based on the asymptotic hyperbolic character of the Kobayashi or Bergman metrics and on the Bonk-Schramm hyperbolic fillings.


Predicting Circadian Misalignment With Wearable Technology: Validation Of Wrist-Worn Actigraphy And Photometry In Night Shift Workers, Philip Cheng, Olivia Walch, Yitong Huang, Caleb Mayer, Chaewon Sagong, Andrea Cuamatzi Castelan, Helen J. Burgess, Thomas Roth, Daniel B. Forger, Christopher L. Drake Feb 2021

Predicting Circadian Misalignment With Wearable Technology: Validation Of Wrist-Worn Actigraphy And Photometry In Night Shift Workers, Philip Cheng, Olivia Walch, Yitong Huang, Caleb Mayer, Chaewon Sagong, Andrea Cuamatzi Castelan, Helen J. Burgess, Thomas Roth, Daniel B. Forger, Christopher L. Drake

Mathematics Sciences: Faculty Publications

Study Objectives: A critical barrier to successful treatment of circadian misalignment in shift workers is determining circadian phase in a clinical or field setting. Light and movement data collected passively from wrist actigraphy can generate predictions of circadian phase via mathematical models; however, these models have largely been tested in non-shift working adults. This study tested the feasibility and accuracy of actigraphy in predicting dim light melatonin onset (DLMO) in fixed night shift workers. Methods: A sample of 45 night shift workers wore wrist actigraphs before completing DLMO in the laboratory (17.0 days ± 10.3 SD). DLMO was assessed via …


Courant Cohomology, Cartan Calculus, Connections, Curvature, Characteristic Classes, Miquel Cueca, Rajan Amit Mehta Feb 2021

Courant Cohomology, Cartan Calculus, Connections, Curvature, Characteristic Classes, Miquel Cueca, Rajan Amit Mehta

Mathematics Sciences: Faculty Publications

We give an explicit description, in terms of bracket, anchor, and pairing, of the standard cochain complex associated to a Courant algebroid. In this formulation, the differential satisfies a formula that is formally identical to the Cartan formula for the de Rham differential. This perspective allows us to develop the theory of Courant algebroid connections in a way that mirrors the classical theory of connections. Using a special class of connections, we construct secondary characteristic classes associated to any Courant algebroid.


Computing Ribbon Obstructions For Colored Knots, Patricia Cahn, Alexandra Kjuchukova Jan 2021

Computing Ribbon Obstructions For Colored Knots, Patricia Cahn, Alexandra Kjuchukova

Mathematics Sciences: Faculty Publications

Kjuchukova's p invariant gives a ribbon obstruction for Fox p-colored knots. The invariant is derived from dihedral branched covers of 4-manifolds, and can be used to calculate the signatures of these covers when singularities on the branching sets are present. In this note, we give an algorithm for evaluating p from a colored knot diagram, and compute a couple of examples.


Regularity For A Class Of Quasilinear Degenerate Parabolic Equations In The Heisenberg Group, Luca Capogna, Giovanna Citti, Nicola Garofalo Jan 2021

Regularity For A Class Of Quasilinear Degenerate Parabolic Equations In The Heisenberg Group, Luca Capogna, Giovanna Citti, Nicola Garofalo

Mathematics Sciences: Faculty Publications

We extend to the parabolic setting some of the ideas originated with Xiao Zhong's proof in [31] of the Hölder regularity of p-harmonic functions in the Heisenberg group Hn. Given a number p ≥ 2, in this paper we establish the C1 smoothness of weak solutions of a class of quasilinear PDE in Hn modeled on the equation.


Optimal Adjustment Of The Human Circadian Clock In The Real World, Samuel Christensen, Yitong Huang, Olivia J. Walch, Daniel B. Forger Dec 2020

Optimal Adjustment Of The Human Circadian Clock In The Real World, Samuel Christensen, Yitong Huang, Olivia J. Walch, Daniel B. Forger

Mathematics Sciences: Faculty Publications

Which suggestions for behavioral modifications, based on mathematical models, are most likely to be followed in the real world? We address this question in the context of human circadian rhythms. Jet lag is a consequence of the misalignment of the body’s internal circadian (~24-hour) clock during an adjustment to a new schedule. Light is the clock’s primary synchronizer. Previous research has used mathematical models to compute light schedules that shift the circadian clock to a new time zone as quickly as possible. How users adjust their behavior when provided with these optimal schedules remains an open question. Here, we report …


Phyllotaxis As Geometric Canalization During Plant Development, Christophe Godin, Christophe Golé, Stéphane Douady Oct 2020

Phyllotaxis As Geometric Canalization During Plant Development, Christophe Godin, Christophe Golé, Stéphane Douady

Mathematics Sciences: Faculty Publications

Why living forms develop in a relatively robust manner, despite various sources of internal or external variability, is a fundamental question in developmental biology. Part of the answer relies on the notion of developmental constraints: at any stage of ontogenesis, morphogenetic processes are constrained to operate within the context of the current organism being built. One such universal constraint is the shape of the organism itself, which progressively channels the development of the organism toward its final shape. Here, we illustrate this notion with plants, where strikingly symmetric patterns (phyllotaxis) are formed by lateral organs. This Hypothesis article aims first …


“Playing The Whole Game”: A Data Collection And Analysis Exercise With Google Calendar, Albert Y. Kim, Johanna Hardin Aug 2020

“Playing The Whole Game”: A Data Collection And Analysis Exercise With Google Calendar, Albert Y. Kim, Johanna Hardin

Statistical and Data Sciences: Faculty Publications

We provide a computational exercise suitable for early introduction in an undergraduate statistics or data science course that allows students to “play the whole game” of data science: performing both data collection and data analysis. While many teaching resources exist for data analysis, such resources are not as abundant for data collection given the inherent difficulty of the task. Our proposed exercise centers around student use of Google Calendar to collect data with the goal of answering the question “How do I spend my time?” On the one hand, the exercise involves answering a question with near universal appeal, but …


Learning Dynamics From Large Biological Data Sets: Machine Learning Meets Systems Biology, William Gilpin, Yitong Huang, Daniel B. Forger Aug 2020

Learning Dynamics From Large Biological Data Sets: Machine Learning Meets Systems Biology, William Gilpin, Yitong Huang, Daniel B. Forger

Mathematics Sciences: Faculty Publications

In the past few decades, mathematical models based on dynamical systems theory have provided new insight into diverse biological systems. In this review, we ask whether the recent success of machine learning techniques for large-scale biological data analysis provides a complementary or competing approach to more traditional modeling approaches. Recent applications of machine learning to the problem of learning biological dynamics in diverse systems range from neuroscience to animal behavior. We compare the underlying mechanisms and limitations of traditional dynamical models with those of machine learning models. We highlight the unique role that traditional modeling has played in providing predictive …


Integrating Data Science Ethics Into An Undergraduate Major, Benjamin Baumer, Randi L. Garcia, Albert Y. Kim, Katherine M. Kinnaird, Miles Q. Ott Jul 2020

Integrating Data Science Ethics Into An Undergraduate Major, Benjamin Baumer, Randi L. Garcia, Albert Y. Kim, Katherine M. Kinnaird, Miles Q. Ott

Statistical and Data Sciences: Faculty Publications

We present a programmatic approach to incorporating ethics into an undergraduate major in statistical and data sciences. We discuss departmental-level initiatives designed to meet the National Academy of Sciences recommendation for weaving ethics into the curriculum from top-to-bottom as our majors progress from our introductory courses to our senior capstone course, as well as from side-to-side through co-curricular programming. We also provide six examples of data science ethics modules used in five different courses at our liberal arts college, each focusing on a different ethical consideration. The modules are designed to be portable such that they can be flexibly incorporated …


Frobenius Objects In The Category Of Relations, Rajan Amit Mehta, Ruoqi Zhang Jul 2020

Frobenius Objects In The Category Of Relations, Rajan Amit Mehta, Ruoqi Zhang

Mathematics Sciences: Faculty Publications

We give a characterization, in terms of simplicial sets, of Frobenius objects in the category of relations. This result generalizes a result of Heunen, Contreras, and Cattaneo showing that special dagger Frobenius objects in the category of relations are in correspondence with groupoids. As an additional example, we construct a Frobenius object in the category of relations whose elements are certain cohomology classes in a compact oriented Riemannian manifold.


Preparing For A Career At A Liberal Arts College, Julianna Tymoczko Jun 2020

Preparing For A Career At A Liberal Arts College, Julianna Tymoczko

Mathematics Sciences: Faculty Publications

No abstract provided.


A Formula For The Cohomology And K-Class Of A Regular Hessenberg Variety, Erik Insko, Julianna Tymoczko, Alexander Woo May 2020

A Formula For The Cohomology And K-Class Of A Regular Hessenberg Variety, Erik Insko, Julianna Tymoczko, Alexander Woo

Mathematics Sciences: Faculty Publications

Hessenberg varieties are subvarieties of the flag variety parametrized by a linear operator X and a nondecreasing function h. The family of Hessenberg varieties for regular X is particularly important: they are used in quantum cohomology, in combinatorial and geometric representation theory, in Schubert calculus and affine Schubert calculus. We show that the classes of a regular Hessenberg variety in the cohomology and K-theory of the flag variety are given by making certain substitutions in the Schubert polynomial (respectively Grothendieck polynomial) for a permutation that depends only on h. Our formula and our methods are different from a recent result …


Circada: Shiny Apps For Exploration Of Experimental And Synthetic Circadian Time Series With An Educational Emphasis, Lisa Cenek, Liubou Klindziuk, Cindy Lopez, Eleanor Mccartney, Blanca Martin Burgos, Selma Tir, Mary E. Harrington, Tanya L. Leise Apr 2020

Circada: Shiny Apps For Exploration Of Experimental And Synthetic Circadian Time Series With An Educational Emphasis, Lisa Cenek, Liubou Klindziuk, Cindy Lopez, Eleanor Mccartney, Blanca Martin Burgos, Selma Tir, Mary E. Harrington, Tanya L. Leise

Psychology: Faculty Publications

Circadian rhythms are daily oscillations in physiology and behavior that can be assessed by recording body temperature, locomotor activity, or bioluminescent reporters, among other measures. These different types of data can vary greatly in waveform, noise characteristics, typical sampling rate, and length of recording. We developed 2 Shiny apps for exploration of these data, enabling visualization and analysis of circadian parameters such as period and phase. Methods include the discrete wavelet transform, sine fitting, the Lomb-Scargle periodogram, autocorrelation, and maximum entropy spectral analysis, giving a sense of how well each method works on each type of data. The apps also …


How Emergent Social Patterns In Allogrooming Combat Parasitic Infections, Shelby N. Wilson, Suzanne S. Sindi, Heather Z. Brooks, Maryann E. Hohn, Candice R. Price, Ami E. Radunskaya, Nakeya D. Williams, Nina H. Fefferman Mar 2020

How Emergent Social Patterns In Allogrooming Combat Parasitic Infections, Shelby N. Wilson, Suzanne S. Sindi, Heather Z. Brooks, Maryann E. Hohn, Candice R. Price, Ami E. Radunskaya, Nakeya D. Williams, Nina H. Fefferman

Mathematics Sciences: Faculty Publications

Members of social groups risk infection through contact with those in their social network. Evidence that social organization may protect populations from pathogens in certain circumstances prompts the question as to how social organization affects the spread of ectoparasites. The same grooming behaviors that establish social bonds also play a role in the progression of ectoparasitic outbreaks. In this paper, we model the interactions between social organization and allogrooming efficiency to consider how ectoparasitic threats may have shaped the evolution of social behaviors. To better understand the impacts of social grooming on organizational structure, we consider several dynamic models of …


A Permutation Test And Spatial Cross-Validation Approach To Assess Models Of Interspecific Competition Between Trees, David Allen, Albert Y. Kim Mar 2020

A Permutation Test And Spatial Cross-Validation Approach To Assess Models Of Interspecific Competition Between Trees, David Allen, Albert Y. Kim

Statistical and Data Sciences: Faculty Publications

Measuring species-specific competitive interactions is key to understanding plant communities. Repeat censused large forest dynamics plots offer an ideal setting to measure these interactions by estimating the species-specific competitive effect on neighboring tree growth. Estimating these interaction values can be difficult, however, because the number of them grows with the square of the number of species. Furthermore, confidence in the estimates can be overestimated if any spatial structure of model errors is not considered. Here we measured these interactions in a forest dynamics plot in a transitional oak-hickory forest. We analytically fit Bayesian linear regression models of annual tree radial …