1,588 Hits in 1.9 sec

Soil extracellular enzyme activities from a forest harvest and climate manipulation experiment in central Pennsylvania

Marshall McDaniel, Marshall McDaniel, Jason Kaye, Mary Ann Bruns, Margot Kaye
2011 Nature Precedings  
doi:10.1038/npre.2011.6254 fatcat:te36ey4a2veijmnjzevobtliru

Soil extracellular enzyme activities from a forest harvest and climate manipulation experiment in central Pennsylvania

Marshall McDaniel, Marshall McDaniel, Jason Kaye, Mary Ann Bruns, Margot Kaye
2011 Nature Precedings  
doi:10.1038/npre.2011.6254.2 fatcat:w4vagcvafzbi5ifwab3p2rjvtu

Soil extracellular enzyme activities from a forest harvest and climate manipulation experiment in central Pennsylvania

Marshall McDaniel, Marshall McDaniel, Jason Kaye, Mary Ann Bruns, Margot Kaye
2011 Nature Precedings  
doi:10.1038/npre.2011.6254.1 fatcat:sy53iiwz2bgqjirxma7hhnxdwe

Analysis of single-excitation states in quantum optics [article]

Jeremy Hoskins, Jason Kaye, Manas Rachh, John Schotland
2021 arXiv   pre-print
In this paper we analyze the dynamics of single-excitation states, which model the scattering of a single photon from multiple two level atoms. For short times and weak atom-field couplings we show that the atomic amplitudes are given by a sum of decaying exponentials, where the decay rates and Lamb shifts are given by the poles of a certain analytic function. This result is a refinement of the "pole approximation" appearing in the standard Wigner-Weisskopf analysis of spontaneous emission. On
more » ... he other hand, at large times, the atomic field decays like O(1/t^3) with a known constant expressed in terms of the coupling parameter and the resonant frequency of the atoms. Moreover, we show that for stronger coupling, the solutions also feature a collection of oscillatory exponentials which dominate the behavior at long times. Finally, we extend the analysis to the continuum limit in which atoms are distributed according to a given density.
arXiv:2110.07049v1 fatcat:z634bcy64bfntaapfo3groqivq


Jason P. Kaye, Stephen C. Hart, Peter Z. Fulé, W. Wallace Covington, Margaret M. Moore, Margot W. Kaye
2005 Ecological Applications  
Net N mineralization data from 1995 are from Kaye and Hart (1998a) .  ...  et al. 1999) , allowing longer storage of winter precipitation in soils (Feeney et al. 1998, Kaye and Hart 1998b) .  ... 
doi:10.1890/04-0868 fatcat:e7indte3rbefvbshptt4pm6ouq

Attention-Related Pearce-Kaye-Hall Signals in Basolateral Amygdala Require the Midbrain Dopaminergic System

Guillem R. Esber, Matthew R. Roesch, Shreya Bali, Jason Trageser, Gregory B. Bissonette, Adam C. Puche, Peter C. Holland, Geoffrey Schoenbaum
2012 Biological Psychiatry  
Neural activity in basolateral amygdala has recently been shown to reflect surprise or attention as predicted by the Pearce-Kaye-Hall model (PKH)--an influential model of associative learning.  ...  However, a lagging unsigned prediction error is precisely what the amended Pearce-Hall model (17) proposes (Pearce, Kaye & Hall, henceforward PKH) as a mechanism for attentional changes in learning.  ...  Finally, we also examined activity across trials in the neurons that fired more early in learning, looking specifically for the integration that is a hallmark of the attentional signal proposed by Pearce, Kaye  ... 
doi:10.1016/j.biopsych.2012.05.023 pmid:22763185 pmcid:PMC3465645 fatcat:b5qndr32nfcqfnifiyw54furwm

Slow carbon and nutrient accumulation in trees established following fire exclusion in the southwestern United States

Jason P. Kaye, Margot W. Kaye, Stephen C. Hart, W. Wallace Covington, Peter Z. Fulé
2016 Ecological Applications  
and Hart 1998a , Kaye et al. 2005 , Grady and Hart 2006 , Kurth et al. 2014 .  ...  To convert tree biomass to C mass, we assumed that 0.48% of all tree mass was C (Kaye et al. 2005) .  ... 
doi:10.1002/eap.1407 pmid:27859967 fatcat:5vblew2lsrerbaq42d4ql76rdy

A fast solver for the narrow capture and narrow escape problems in the sphere [article]

Jason Kaye, Leslie Greengard
2019 arXiv   pre-print
We present an efficient method to solve the narrow capture and narrow escape problems for the sphere. The narrow capture problem models the equilibrium behavior of a Brownian particle in the exterior of a sphere whose surface is reflective, except for a collection of small absorbing patches. The narrow escape problem is the dual problem: it models the behavior of a Brownian particle confined to the interior of a sphere whose surface is reflective, except for a collection of small patches
more » ... which it can escape. Mathematically, these give rise to mixed Dirichlet/Neumann boundary value problems of the Poisson equation. They are numerically challenging for two main reasons: (1) the solutions are non-smooth at Dirichlet-Neumann interfaces, and (2) they involve adaptive mesh refinement and the solution of large, ill-conditioned linear systems when the number of small patches is large. By using the Neumann Green's functions for the sphere, we recast each boundary value problem as a system of first-kind integral equations on the collection of patches. A block-diagonal preconditioner together with a multiple scattering formalism leads to a well-conditioned system of second-kind integral equations and a very efficient approach to discretization. This system is solved iteratively using GMRES. We develop a hierarchical, fast multipole method-like algorithm to accelerate each matrix-vector product. Our method is insensitive to the patch size, and the total cost scales with the number N of patches as O(N log N), after a precomputation whose cost depends only on the patch size and not on the number or arrangement of patches. We demonstrate the method with several numerical examples, and are able to achieve highly accurate solutions with 100,000 patches in one hour on a 60-core workstation.
arXiv:1906.04209v1 fatcat:hmimkzve6fglja6cyaa7u4ayey

A high-order integral equation-based solver for the time-dependent Schrodinger equation [article]

Jason Kaye, Alex Barnett, Leslie Greengard
2020 arXiv   pre-print
We introduce a numerical method for the solution of the time-dependent Schrodinger equation with a smooth potential, based on its reformulation as a Volterra integral equation. We present versions of the method both for periodic boundary conditions, and for free space problems with compactly supported initial data and potential. A spatially uniform electric field may be included, making the solver applicable to simulations of light-matter interaction. The primary computational challenge in
more » ... the Volterra formulation is the application of a space-time history dependent integral operator. This may be accomplished by projecting the solution onto a set of Fourier modes, and updating their coefficients from one time step to the next by a simple recurrence. In the periodic case, the modes are those of the usual Fourier series, and the fast Fourier transform (FFT) is used to alternate between physical and frequency domain grids. In the free space case, the oscillatory behavior of the spectral Green's function leads us to use a set of complex-frequency Fourier modes obtained by discretizing a contour deformation of the inverse Fourier transform, and we develop a corresponding fast transform based on the FFT. Our approach is related to pseudo-spectral methods, but applied to an integral rather than the usual differential formulation. This has several advantages: it avoids the need for artificial boundary conditions, admits simple, inexpensive high-order implicit time marching schemes, and naturally includes time-dependent potentials. We present examples in one and two dimensions showing spectral accuracy in space and eighth-order accuracy in time for both periodic and free space problems.
arXiv:2001.06113v1 fatcat:p2twwnphrvfb3kdzvbtovxfwkm

Discrete Lehmann representation of imaginary time Green's functions [article]

Jason Kaye and Kun Chen and Olivier Parcollet
2022 arXiv   pre-print
We present an efficient basis for imaginary time Green's functions based on a low rank decomposition of the spectral Lehmann representation. The basis functions are simply a set of well-chosen exponentials, so the corresponding expansion may be thought of as a discrete form of the Lehmann representation using an effective spectral density which is a sum of δ functions. The basis is determined only by an upper bound on the product βω_max, with β the inverse temperature and ω_max an energy
more » ... and a user-defined error tolerance ϵ. The number r of basis functions scales as 𝒪(log(βω_max) log (1/ϵ)). The discrete Lehmann representation of a particular imaginary time Green's function can be recovered by interpolation at a set of r imaginary time nodes. Both the basis functions and the interpolation nodes can be obtained rapidly using standard numerical linear algebra routines. Due to the simple form of the basis, the discrete Lehmann representation of a Green's function can be explicitly transformed to the Matsubara frequency domain, or obtained directly by interpolation on a Matsubara frequency grid. We benchmark the efficiency of the representation on simple cases, and with a high precision solution of the Sachdev-Ye-Kitaev equation at low temperature. We compare our approach with the related intermediate representation method, and introduce an improved algorithm to build the intermediate representation basis and a corresponding sampling grid.
arXiv:2107.13094v2 fatcat:yujqz2vfbfav7ecevol4mnzzla

Linking Carbon Saturation Concepts to Nitrogen Saturation and Retention

Michael J. Castellano, Jason P. Kaye, Henry Lin, John P. Schmidt
2011 Ecosystems  
These recent advances in C saturation theory combined with the tight coupling of C and N in SOM (Kaye and others 2002; Cleveland and Liptzin 2007; Stewart and others 2007) led us to develop a new conceptual  ...  mechanism also applies to the retention of inorganic N inputs in SOM, which occurs primarily through rapid microbial transformation of inorganic N to DON (Norton and Firestone 1996; Zogg and others 2000; Kaye  ... 
doi:10.1007/s10021-011-9501-3 fatcat:uhpz6hznrvegfnv3aqxrrznd4y

Estimating soil properties in heterogeneous land-use patches: a Bayesian approach

Jacob J. Oleson, Diane Hope, Corinna Gries, Jason Kaye
2006 Environmetrics  
Cities provide unique opportunities for integrating humans into ecology. Using data from a socio-ecological inventory of metropolitan Phoenix, Arizona, we explore the contribution of human-related variables to explaining observed variation in soil nitrate-N (NO 3 --N) and total carbon (C) concentrations across the city, agricultural fields, surrounding desert, and mixed regions. Conventional modeling approaches in such a setting would lead to examination of spatial relationships over the entire
more » ... study area or on subsets of the data independently. However, the spatial relationships for NO 3 --N and C may be different in each of these regions. Here we estimate the correlation coefficients for influential variables toward soil NO 3 --N and C across the entire region, while at the same time accounting for potentially differing spatial patterns in each of these regions. Soil NO 3 --N shows markedly greater spatial autocorrelation in the desert regions, while the soil C shows varying amounts of spatial relationships in the different regions.
doi:10.1002/env.789 fatcat:2oqpcuinrjcnphuezzso75iedi

A fast time domain solver for the equilibrium Dyson equation [article]

Jason Kaye, Hugo U. R. Strand
2022 arXiv   pre-print
We consider the numerical solution of the real time equilibrium Dyson equation, which is used in calculations of the dynamical properties of quantum many-body systems. We show that this equation can be written as a system of coupled, nonlinear, convolutional Volterra integro-differential equations, for which the kernel depends self-consistently on the solution. As is typical in the numerical solution of Volterra-type equations, the computational bottleneck is the quadratic-scaling cost of
more » ... y integration. However, the structure of the nonlinear Volterra integral operator precludes the use of standard fast algorithms. We propose a quasilinear-scaling FFT-based algorithm which respects the structure of the nonlinear integral operator. The resulting method can reach large propagation times, and is thus well-suited to explore quantum many-body phenomena at low energy scales. We demonstrate the solver with two standard model systems: the Bethe graph, and the Sachdev-Ye-Kitaev model.
arXiv:2110.06120v2 fatcat:lhxcb5sawra75gv2anigsvm7wi


Jason P. Kaye, Stephen C. Hart
1998 Ecological Applications  
Kaye, D. Neary, P. Matson, and one anonymous reviewer greatly improved the manuscript.  ...  Soil is more mobile, and thus more accessible to Kaye and Hart 1997) .  ... 
doi:10.1890/1051-0761(1998)008[1052:eranti];2 fatcat:5nd4fmwrvfbyzecvnbg53xi4yy

Proposed Best Practices for Collaboration at Cross-disciplinary Observatories

Jason Philip Kaye, Susan Louise Brantley, Jennifer Zan Williams, the SSHCZO team
2019 Biogeosciences Discussions  
<p><strong>Abstract.</strong> Interdisciplinary science affords new opportunities but also presents new challenges for biogeosciences collaboration. Since 2007, we have conducted site-based interdisciplinary research in central PA, USA at the Susquehanna Shale Hills Critical Zone Observatory. Early in our collaboration, we realized the need for some best practices that could guide our project team. While we found some guidelines for determining authorship on papers, we found fewer guidelines
more » ... cribing how to collaboratively establish field sites, share instrumentation, share model code, and share data. Thus, we worked as a team to develop a best practices document that is presented here. While this work is based on one large team project, we think many of the themes are universal and we present our example to provide a building block for improving the function of interdisciplinary biogeoscience teams.</p>
doi:10.5194/bg-2019-249 fatcat:5zwckvdfkfbiflxthouazvvx6u
« Previous Showing results 1 — 15 out of 1,588 results