Evaluation of Herbicides for Saltcedar Control in Southwest Kansas

Saltcedar is an invasive species along some of the major rivers and tributaries in Kansas. The objective of this study is to determine control of saltcedar in southwestern Kansas using herbicides applied to individual trees as cut-stump, basal, and foliar treatments. Cut-stump treatments were applied in 2004-2010 during the months of April or May. Basal applications with 10% triclopyr in diesel were applied between 2007-2021 during the months of August through early October. Foliar treatments were applied during 2008-2021 using 467 L/ha spray volumes during August through early October. Chi square analysis at P \u3c 0.05 was used to compare treatments. In initial studies, imazapyr (Arsenal) at 10% v/v in water, triclopyr (Remedy) at 10% v/v in diesel, and undiluted triclopyr (Pathfinder II) provided 80- 100% control of saltcedar, and were more effective than triclopyr + 2,4-D (Crossbow) applied as a 4% v/v solution in diesel (60% control). During 2008-2010, 10% imazapyr, 50% glyphosate, glyphosate + imazapyr (0.5% + 0.5%), triclopyr at 10 or 25%, and a mixture of triclopyr + fluroxypyr (PastureGard) at 25% all provided greater than 91% control of saltcedar. Basal bark control using 10% v/v triclopyr in diesel averaged 72% control. Foliar applications with 0.5 or 1% imazapyr and 0.5% + 1% imazapyr + glyphosate all provided greater than 84% control of saltcedar treated in 2008-2011. Imazapic (Plateau) at 1% was first compared with 1% imazapyr during 2014-2016 with both treatments providing about 80% control. During 2017-2021, 1% imazapyr (82% control), 1% imazapic (79% control), and 0.5% + 0.5% imazapyr + glyphosate (92% control) were all more effective than a combination of aminopyralid (Milestone) + triclopyr applied at 239 g/L + 359 g/L (42% control). Herbicides can be applied as cutstump, basal bark, or foliar treatments for the control of saltcedar

Exponential decay in a spin bath

We show that the coherence of an electron spin interacting with a bath of nuclear spins can exhibit a well-defined purely exponential decay for special (`narrowed') bath initial conditions in the presence of a strong applied magnetic field. This is in contrast to the typical case, where spin-bath dynamics have been investigated in the non-Markovian limit, giving super-exponential or power-law decay of correlation functions. We calculate the relevant decoherence time T_2 explicitly for free-induction decay and find a simple expression with dependence on bath polarization, magnetic field, the shape of the electron wave function, dimensionality, total nuclear spin I, and isotopic concentration for experimentally relevant heteronuclear spin systems.Comment: 4+ pages, 3 figures; v2: 9 pages, 3 figures (added four appendices with extensive technical details, version to appear in Phys. Rev. B

Memory-Controlled Diffusion

Memory effects require for their incorporation into random-walk models an extension of the conventional equations. The linear Fokker-Planck equation for the probability density $p(\vec r, t)$ is generalized to include non-linear and non-local spatial-temporal memory effects. The realization of the memory kernels are restricted due the conservation of the basic quantity $p$. A general criteria is given for the existence of stationary solutions. In case the memory kernel depends on $p$ polynomially the transport is prevented. Owing to the delay effects a finite amount of particles remains localized and the further transport is terminated. For diffusion with non-linear memory effects we find an exact solution in the long-time limit. Although the mean square displacement shows diffusive behavior, higher order cumulants exhibits differences to diffusion and they depend on the memory strength

Free-induction decay and envelope modulations in a narrowed nuclear spin bath

We evaluate free-induction decay for the transverse components of a localized electron spin coupled to a bath of nuclear spins via the Fermi contact hyperfine interaction. Our perturbative treatment is valid for special (narrowed) bath initial conditions and when the Zeeman energy of the electron $b$ exceeds the total hyperfine coupling constant $A$: $b>A$. Using one unified and systematic method, we recover previous results reported at short and long times using different techniques. We find a new and unexpected modulation of the free-induction-decay envelope, which is present even for a purely isotropic hyperfine interaction without spin echoes and for a single nuclear species. We give sub-leading corrections to the decoherence rate, and show that, in general, the decoherence rate has a non-monotonic dependence on electron Zeeman splitting, leading to a pronounced maximum. These results illustrate the limitations of methods that make use of leading-order effective Hamiltonians and re-exponentiation of short-time expansions for a strongly-interacting system with non-Markovian (history-dependent) dynamics.Comment: 13 pages, 9 figure

Selfconsistent Approximations in Mori's Theory

The constitutive quantities in Mori's theory, the residual forces, are expanded in terms of time dependent correlation functions and products of operators at $t=0$, where it is assumed that the time derivatives of the observables are given by products of them. As a first consequence the Heisenberg dynamics of the observables are obtained as an expansion of the same type. The dynamic equations for correlation functions result to be selfconsistent nonlinear equations of the type known from mode-mode coupling approximations. The approach yields a neccessary condition for the validity of the presented equations. As a third consequence the static correlations can be calculated from fluctuation-dissipation theorems, if the observables obey a Lie algebra. For a simple spin model the convergence of the expansion is studied. As a further test, dynamic and static correlations are calculated for a Heisenberg ferromagnet at low temperatures, where the results are compared to those of a Holstein Primakoff treatment.Comment: 51 pages, Latex, 3 eps figures included, elsart and epsf style files included, also available at http://athene.fkp.physik.th-darmstadt.de/public/wolfram.html and ftp://athene.fkp.physik.th-darmstadt.de/pub/publications/wolfram

Singlet-triplet decoherence due to nuclear spins in a double quantum dot

We have evaluated hyperfine-induced electron spin dynamics for two electrons confined to a double quantum dot. Our quantum solution accounts for decay of a singlet-triplet correlator even in the presence of a fully static nuclear spin system, with no ensemble averaging over initial conditions. In contrast to an earlier semiclassical calculation, which neglects the exchange interaction, we find that the singlet-triplet correlator shows a long-time saturation value that differs from 1/2, even in the presence of a strong magnetic field. Furthermore, we find that the form of the long-time decay undergoes a transition from a rapid Gaussian to a slow power law ($\sim 1/t^{3/2}$) when the exchange interaction becomes nonzero and the singlet-triplet correlator acquires a phase shift given by a universal (parameter independent) value of $3\pi/4$ at long times. The oscillation frequency and time-dependent phase shift of the singlet-triplet correlator can be used to perform a precision measurement of the exchange interaction and Overhauser field fluctuations in an experimentally accessible system. We also address the effect of orbital dephasing on singlet-triplet decoherence, and find that there is an optimal operating point where orbital dephasing becomes negligible.Comment: 12 pages, 4 figure

Improving workforce experiences at United States Federally Qualified Health Centers: Exploring the perceived impact of generational diversity on employee engagement

This qualitative study aimed to explore a multigenerational workforce’s impact on employee engagement as perceived by Federally Qualified Health Centers’ (FQHCs) C-suite executives. It sought to answer one research question: What is the perceived impact of generational diversity on employee engagement of Federally Qualified Health Centers (FQHCs) in the United States? This cross-sectional study was national. Primary data were collected using a self-developed, two-part survey instrument: (1) eight demographic questions and (2) two open-ended, short-answer questions. Cognitive interviews, reviews by five subject matter experts, and a pilot study were completed to ensure the instrument’s validity and reliability. Demographic data were analyzed using Minitab V19, and qualitative data were analyzed using MAXQDA V2020. The final sample (n=81) represented 6% of the 1,400 U.S. FQHCs and consisted of respondents from all five U.S. geographic regions: Northeast, Southeast, Midwest, Southwest, and West. Of the 81 FQHCs, one-third had a four-generation workforce, and over one-half had a five-generation workforce. A multigenerational workforce was important and necessary because of enhanced work creativity, improved problem solving, and a better representation of FQHCs’ diverse patients. Conversely, a multigenerational workforce also presented challenges, including the need to address generation-specific expectations, family dynamics, rewards and recognition, technology proficiency, and learning and training opportunities. Engaging a multigenerational workforce presented benefits and challenges. The benefits included fostering a sense of learning culture, transferring knowledge and skills, and promoting more representative patient communities which FQHC employees served. The challenges included varied expectations, different communication styles, and inter-generation perceptions in healthcare workplaces. Experience Framework This article is associated with the Staff & Provider Engagement lens of The Beryl Institute Experience Framework (https://www.theberylinstitute.org/ExperienceFramework). Access other PXJ articles related to this lens. Access other resources related to this lens

Effects of corn steep liquor supplementation on performance and herbivory patterns of beef

Increased grazing pressure on sericea lespedeza by beef cattle, the most economically relevant herbivore in the region, may slow its spread and facilitate some measure of biological control. Unfortunately, mature plants contain high levels of condensed tannins that decrease protein digestion by beef cattle, and these compounds are potent deterrents to grazing. Supplementing corn steep liquor has been shown to alleviate the negative effects associated with ingestion of condensed tannins when beef cattle are fed prairie hay contaminated with sericea lespedeza. In addition, beef cows supplemented with corn steep liquor did not discriminate between sericea lespedeza-contaminated and sericea lespedeza-free prairie hay in a preference trial. Therefore, the objective of our study was to evaluate the effects of supplemental corn steep liquor on herbivory patterns and performance of beef cows grazing native tallgrass rangeland infested with sericea lespedeza

Hyperfine interaction in a quantum dot: Non-Markovian electron spin dynamics

We have performed a systematic calculation for the non-Markovian dynamics of a localized electron spin interacting with an environment of nuclear spins via the Fermi contact hyperfine interaction. This work applies to an electron in the s -type orbital ground state of a quantum dot or bound to a donor impurity, and is valid for arbitrary polarization p of the nuclear spin system, and arbitrary nuclear spin I in high magnetic fields. In the limit of p=1 and I=1/2, the Born approximation of our perturbative theory recovers the exact electron spin dynamics. We have found the form of the generalized master equation (GME) for the longitudinal and transverse components of the electron spin to all orders in the electron spin--nuclear spin flip-flop terms. Our perturbative expansion is regular, unlike standard time-dependent perturbation theory, and can be carried-out to higher orders. We show this explicitly with a fourth-order calculation of the longitudinal spin dynamics. In zero magnetic field, the fraction of the electron spin that decays is bounded by the smallness parameter \delta=1/p^{2}N, where N is the number of nuclear spins within the extent of the electron wave function. However, the form of the decay can only be determined in a high magnetic field, much larger than the maximum Overhauser field. In general the electron spin shows rich dynamics, described by a sum of contributions with non-exponential decay, exponential decay, and undamped oscillations. There is an abrupt crossover in the electron spin asymptotics at a critical dimensionality and shape of the electron envelope wave function. We propose a scheme that could be used to measure the non-Markovian dynamics using a standard spin-echo technique, even when the fraction that undergoes non-Markovian dynamics is small.Comment: 22 pages, 8 figure

Rigorous Born Approximation and beyond for the Spin-Boson Model

Within the lowest-order Born approximation, we present an exact calculation of the time dynamics of the spin-boson model in the ohmic regime. We observe non-Markovian effects at zero temperature that scale with the system-bath coupling strength and cause qualitative changes in the evolution of coherence at intermediate times of order of the oscillation period. These changes could significantly affect the performance of these systems as qubits. In the biased case, we find a prompt loss of coherence at these intermediate times, whose decay rate is set by $\sqrt{\alpha}$, where $\alpha$ is the coupling strength to the environment. We also explore the calculation of the next order Born approximation: we show that, at the expense of very large computational complexity, interesting physical quantities can be rigorously computed at fourth order using computer algebra, presented completely in an accompanying Mathematica file. We compute the $O(\alpha)$ corrections to the long time behavior of the system density matrix; the result is identical to the reduced density matrix of the equilibrium state to the same order in $\alpha$. All these calculations indicate precision experimental tests that could confirm or refute the validity of the spin-boson model in a variety of systems.Comment: Greatly extended version of short paper cond-mat/0304118. Accompanying Mathematica notebook fop5.nb, available in Source, is an essential part of this work; it gives full details of the fourth-order Born calculation summarized in the text. fop5.nb is prepared in arXiv style (available from Wolfram Research