Characterizing Arbuscular Mycorrhizal Associations in Corn Inoculated with Soil from Till or No-Till Farmlands

Many crops have mutualistic arbuscular mycorrhizal fungi(AMF) associations that positively affect plant and soil health. AMF likely mitigates agricultural problems like topsoil depletion and compaction from tilling. The literature review on AMF associations under different practices showed the need for more studies. This project studied an AMF community\u27s impact on soil quality and plant health in conventional till(CT) and no-till(NT) managed corn and soybean plants. Data was gathered from these fields in West MI, using field soil to inoculate greenhouse plants in normal/drought conditions. Three types of data were collected for each case: 1)AMF community via spore type and presence, 2)Soil structure via aggregate size and nutrient quantity, and 3)Plant productivity via root-shoot biomass ratio and structure. This study will provide an update of our ongoing data collection and analysis. This study aims to describe the conditions where AMF benefit crop production and soil quality locally

Integrating Social Justice Practices into Graduate Training: Collaborating with Stakeholders to Adapt Professional Development in Puerto Rico

Treating trauma has become an international social justice concern, with increasing numbers of graduate training programs prioritizing how to conceptualize needs and interventions within a trauma-informed framework. Minimal research and guidelines exist for adapting these trauma-informed practices for the local community context. Additionally, trauma-informed practices often fail to consider ongoing structural issues faced by oppressed communities such as poverty and racism. Social work, psychology, and counseling graduate training programs often rely on a cultural competency framework instead of a social justice framework that addresses racism and Whiteness. During our graduate Counseling and School Psychology training program at the University of Massachusetts Boston, we collaborated with stakeholders at a school and community center in San Juan, Puerto Rico to culturally adapt and deliver trainings in trauma-informed practices for staff using an ecological validity framework. Using our work in Puerto Rico as a case study, this paper addresses the cultural adaptation of trauma-informed practices and factors to consider when implementing trauma-informed practices, emphasizing the need for creating safety. Strategies for embedding this trauma-informed work into mental health graduate training programs and recommendations for working with individuals from marginalized groups in school settings are discussed

The resonant damping of oscillations of coronal loops with elliptic cross-sections

Motivated by recent Transition Region and Coronal Explorer (TRACE) observations of damped oscillations in coronal loops, Ruderman & Roberts (2002), studied resonant damping of kink oscillations of thin straight magnetic tubes in a cold plasma. In their analysis, Ruderman & Roberts considered magnetic tubes with circular cross-sections. We extend their analysis for magnetic tubes with elliptic cross-sections. We find that there are two infinite sequences of the eigenfrequencies of the tube oscillations, {omega(nc)} and {omega(ns)}, n = 1,2,.... The eigenfrequencies {omega(nc)} and {omega(ns)} correspond to modes with 2n nodes at the tube boundary. In particular, omega(1c) and omega(1s) correspond to two kink modes. These modes are linearly polarized in the direction of the large and small axis of the tube elliptic cross-section respectively. The sequence {omega(nc)} is monotonically growing and {omega(ns)} monotonically decreasing, and they both tend to omega(k) as n --> infinity, where omega(k) is the frequency of the kink mode of tubes with circular cross-sections. In particular, omega(1c) < omega(k) < omega(1s). We calculate the decrements of the two kink modes and show that they are of the order of decrement of the kink mode of a tube with a circular cross-section

Towards a Practical Behavior Analytic Multitiered Consultation Model for Early Childhood Educators

Early childhood educators are in a critical position to support young children’s social-emotional, behavioral, and learning development, which can be accomplished through consistent use of evidence-based practices delivered in day-to-day interactions. However, early childhood educators may require support for implementing evidence-based practices. The purpose of this paper is to introduce a novel form of behavioral consultation for early childhood educators. Specifically, a behavior analytic multitiered consultation model in which implementation supports become increasingly more intensive is described. Rationale, implementation, evidence-base, and implications for practice and research are described. Finally, this paper concludes with an empirical case study to illustrate this model’s implementation. This paper is also meant to serve as a call-to-action for researchers and practitioners to replicate this consultation model

Vein interposition cuffs decrease the intimal hyperplastic response of polytetrafluoroethylene bypass grafts

AbstractPurpose: The modification of the distal anastomosis of polytetrafluoroethylene (PTFE) bypass grafts with vein interposition cuffs (VCs) has been reported to increase graft patency. However, the mechanisms that are responsible for this improved patency are unclear. Because intimal hyperplasia (IH) is a primary cause of prosthetic graft failure, we hypothesized that VCs affect the distal anastomosis by decreasing the IH response of the outflow artery. Methods: Twenty-three female domestic Yorkshire pigs (mean weight, 35 kg) underwent 42 femoral PTFE bypass grafting procedures. The PTFE bypass grafts were separated into the following three groups according to distal anastomotic configuration: end-to-side anastomoses (ES), VCs, and cuffs constructed with PTFE (PCs). Four femoral arteries from two pigs served as healthy controls. At sacrifice, the grafts were perfusion fixed, and the distal anastomoses harvested at 1 and 4 weeks. The specimens were hemisected and serially sectioned to identify the heel, toe, and mid-anastomotic regions. The sections were cut into 5-μm segments and analyzed for intima and media thickness and area, intima/media area ratio, and the distribution of IH in the vein cuff. The roles of transforming growth factor–β1 and platelet-derived growth factor–BB in IH development were assessed with immunohistochemistry. Results: IH development was significantly lower at all areas of the anastomosis, with VCs compared with ES and PCs at 4 weeks (P ≤ .001). IH decreased in VCs from 1 to 4 weeks in all areas of the anastomosis (P ≤ .001). PCs showed pronounced IH at the mid-anastomosis as compared with VCs and ES (P ≤ .001). IH was most pronounced at the toe with ES and PCs (P ≤ .001). Qualitatively, VCs altered the site of IH development, sparing the recipient artery with preferential thickening of the vein cuff and formation of a pseudointima at the vein-PTFE interface. Immunohistochemistry results showed positive staining for transforming growth factor–β1, platelet-derived growth factor–BB, and smooth muscle α-actin in the hyperplastic intima. Conclusion: PTFE bypass grafts with VCs had less IH develop than did grafts with ES and PC anastomoses. IH regression in VCs at 4 weeks suggests compensatory vessel wall remodeling mediated by the presence of the VC. Furthermore, VCs caused a redistribution of hyperplasia to the vein-PTFE interface, delaying IH-induced outflow obstruction in the recipient artery. The marked increase in IH with PCs, despite a similar geometric configuration to VCs, suggests that the biologic properties of autogenous tissue dissipate IH development. Similarly, the flow patterns in PCs and VCs should be identical, which suggests a less important role of hemodynamic forces in VC-mediated protection. (J Vasc Surg 2000;31:69-83.

Comparison of the thin flux tube approximation with 3D MHD simulations

The structure and dynamics of small vertical photospheric magnetic flux concentrations has been often treated in the framework of an approximation based upon a low-order truncation of the Taylor expansions of all quantities in the horizontal direction, together with the assumption of instantaneous total pressure balance at the boundary to the non-magnetic external medium. Formally, such an approximation is justified if the diameter of the structure (a flux tube or a flux sheet) is small compared to all other relevant length scales (scale height, radius of curvature, wavelength, etc.). The advent of realistic 3D radiative MHD simulations opens the possibility of checking the consistency of the approximation with the properties of the flux concentrations that form in the course of a simulation. We carry out a comparative analysis between the thin flux tube/sheet models and flux concentrations formed in a 3D radiation-MHD simulation. We compare the distribution of the vertical and horizontal components of the magnetic field in a 3D MHD simulation with the field distribution in the case of the thin flux tube/sheet approximation. We also consider the total (gas plus magnetic) pressure in the MHD simulation box. Flux concentrations with super-equipartition fields are reasonably well reproduced by the second-order thin flux tube/sheet approximation. The differences between approximation and simulation are due to the asymmetry and the dynamics of the simulated structures

Expansion of magnetic flux concentrations: a comparison of Hinode SOT d ata and models

Context: The expansion of network magnetic fields with height is a fundamental property of flux tube models. A rapid expansion is required to form a magnetic canopy. Aims: We characterize the observed expansion properties of magnetic network elements and compare them with the thin flux tube and sheet approximations, as well as with magnetoconvection simulations. Methods: We used data from the Hinode SOT NFI NaD1 channel and spectropolarimeter to study the appearance of magnetic flux concentrations seen in circular polarization as a function of position on the solar disk. We compared the observations with synthetic observables from models based on the thin flux tube approximation and magnetoconvection simulations with two different upper boundary conditions for the magnetic field (potential and vertical). Results: The observed circular polarization signal of magnetic flux concentrations changes from unipolar at disk center to bipolar near the limb, which implies an expanding magnetic field. The observed expansion agrees with expansion properties derived from the thin flux sheet and tube approximations. Magnetoconvection simulations with a potential field as the upper boundary condition for the magnetic field also produce bipolar features near the limb while a simulation with a vertical field boundary condition does not. Conclusions: The near-limb apparent bipolar magnetic features seen in high-resolution Hinode observations can be interpreted using a simple flux sheet or tube model. This lends further support to the idea that magnetic features with vastly varying sizes have similar relative expansion rates. The numerical simulations presented here are less useful in interpreting the expansion since the diagnostics we are interested in are strongly influenced by the choice of the upper boundary condition for the magnetic field in the purely photospheric simulations.Comment: accepted for publication in A&

Thermal stability of a weakly magnetized rotating plasma

The thermal stability of a weakly magnetized, rotating, stratified, optically thin plasma is studied by means of linear-perturbation analysis. We derive dispersion relations and criteria for stability against axisymmetric perturbations that generalize previous results on either non-rotating or unmagnetized fluids. The implications for the hot atmospheres of galaxies and galaxy clusters are discussed.Comment: 16 pages, 3 figures, MNRAS accepted. New figures and corrected equations with respect to previous version. Results unchange

The formation of voids in a universe with cold dark matter and a cosmological constant

A spherical Lagrangian hydrodynamical code has been written to study the formation of cosmological structures in the early Universe. In this code we take into account the presence of collisionless non-baryonic cold dark matter (CDM), the cosmological constant and a series of physical processes present during and after the recombination era, such as photon drag resulting from the cosmic background radiation and hydrogen molecular production. We follow the evolution of the structure since the recombination era until the present epoch. As an application of this code we study the formation of voids starting from negative density perturbations which evolved during and after the recombination era. We analyse a set of COBE-normalized models, using different spectra to see their influence on the formation of voids. Our results show that large voids with diameters ranging from 10h^{-1} Mpc up to 50h^{-1} Mpc can be formed in a universe model dominated by the cosmological constant (\Omega_\Lambda ~ 0.8). This particular scenario is capable of forming large and deep empty regions (with density contrasts \delta < -0.6). Our results also show that the physical processes acting on the baryonic matter produce a transition region where the radius of the dark matter component is greater than the baryonic void radius. The thickness of this transition region ranges from about tens of kiloparsecs up to a few megaparsecs, depending on the spectrum considered. Putative objects formed near voids and within the transition region would have a different amount of baryonic/dark matter when compared with \Omega_b/\Omega_d. If one were to use these galaxies to determine, by dynamical effects or other techniques, the quantity of dark matter present in the Universe, the result obtained would be only local and not representative of the Universe as a whole.Comment: MNRAS (in press); 9 pages, no figure

Thermal Instability in Gravitationally-Stratified Plasmas: Implications for Multi-Phase Structure in Clusters and Galaxy Halos

We study the interplay among cooling, heating, conduction, and magnetic fields in gravitationally stratified plasmas using simplified, plane-parallel numerical simulations. Since the physical heating mechanism remains uncertain in massive halos such as groups or clusters, we adopt a simple, observationally-motivated prescription which enforces global thermal equilibrium when averaged over large scales. The plasma remains susceptible to local thermal instability, however, and cooling drives an inward flow of material. In contrast to previous results, we argue that the thermal stability of the plasma is independent of its convective stability. We find that the ratio of the cooling timescale to the dynamical timescale t_cool/t_ff controls the saturation of the thermal instability: when t_cool/t_ff < 1, the plasma develops extended multi-phase structure, whereas when t_cool / t_ff > 1 it does not. (In a companion paper, we show that the criterion for thermal instability in a spherical potential is somewhat less stringent, t_cool / t_ff < 10.) When thermal conduction is anisotropic with respect to the magnetic field, the criterion for multi-phase structure is essentially independent of the thermal conductivity of the plasma. Our criterion for local thermal instability to produce multi-phase structure is an extension of the cold vs. hot accretion modes in galaxy formation that applies at all radii in hot halos, not just to the virial shock. We show that this criterion is consistent with data on multi-phase gas in the ACCEPT sample of clusters; in addition, when t_cool / t_ff > 1, the net cooling rate to low temperatures and the mass flux to small radii are suppressed enough relative to models without heating to be qualitatively consistent with star formation rates and x-ray line emission in groups and clusters.Comment: This is an electronic version of an article published in Monthly Notices of the Royal Astronomical Society, Volume 419, Issue 4, pp. 3319-333