Scholarworks
ScholarWorks is an open access repository for the capture of the intellectual work of Montana State University (MSU) in support of its teaching, research and service missions. MSU ScholarWorks is a central point of discovery for accessing, collecting, sharing, preserving, and distributing knowledge to the Montana State University community and the world.
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Dynamics of a plant–pollinator network: extending the Bianconi–Barabási model
(Springer Science and Business Media LLC, 2024-06) Castillo, William J.; Burkle, Laura A.; Dormann, Carsten F.
We study the dynamical assembly of weighted bipartite networks to understand the hidden mechanisms of pollination, expanding the Bianconi–Barabási model where nodes have intrinsic properties. Allowing for a non-linear interaction rate, which represents the seasonality of flowers and pollinators, our analysis reveals similarity of this extended Bianconi–Barabási model with field observations. While our current approach may not fully account for the diverse range of interaction accretion slopes observed in the real world, we regard it as an important step towards enriching theoretical models with biological realism.
Morphology, timing, and drivers of post-glacial landslides in the northern Yellowstone region
(Wiley, 2024) Dixon, Jean L.; Nicholas, Grace E.; Pierce, Kenneth L.; Lageson, David
The withdrawal of glaciers in mountainous systems exposes over-steepened slopes previously sculpted by ice. This debuttressing can directly trigger mass movements or leave slopes susceptible to them by other drivers, including seismogenic shaking and changing climate conditions. These systems may pose hazards long after deglaciation. Here, we investigate the drivers of slope failure for landslides at the northern entrance to Yellowstone National Park, a critical conduit traversed by ~1 million visitors each year. Through field mapping and analyses of LiDAR data, we quantify the spatial and temporal relationships between eight adjacent slides. Stratigraphic relationships and surface roughness analyses suggest initial emplacement 13–11.5 ka, after a significant delay from Deckard Flats glacial retreat (15.1 ± 1.2 ka). Thus, rapid glacial debuttressing was not the direct trigger of slope failure, though the resultant change in stress regime likely had a preparatory influence. We posit that the timing of failure was associated with (1) a period of enhanced moisture and seismicity in the late Pleistocene and (2) altered stress regimes associated with ice retreat. Historical archives and cross-cutting relationships indicate portions of some ancient slides were reactivated; these areas are morphologically distinguishable from other slide surfaces, with mean topographic roughness 2 times that of non-active slides. Stream power analysis and archival records indicate Holocene incision of the Gardner River and human disturbances are largely responsible for modern reactivations. Our findings highlight the importance of combining archival records with stratigraphic, field and remote sensing approaches to understanding landslide timing, risk, and drivers in post-glacial environments. This study also provides a valuable baseline for geomorphic change in the Yellowstone system, where a 2022 flood incised streams, damaged infrastructure and further reactivated landslide slopes.
A Comprehensive Protocol for the Collection, Differentiation, Cryopreservation, and Resuscitation of Primary Murine Bone Marrow Derived Macrophages (BMDM)
(Informa UK Limited, 2024-08) Luu, Abby M.; Shepardson, Kelly M.; Rynda-Apple, Agnieszka
Background. The field of immunology has undoubtedly benefited from the in vitro use of cell lines for immunological studies; however, due to the “immortal” nature of many cell lines, they are not always the best model. Thus, direct collection and culture of primary cells from model organisms is a solution that many researchers utilize. To the best of our knowledge, there is not a singular protocol which encompasses the entire process of bone marrow cell collection through cryopreservation and resuscitation of cells from a murine model. Methods. Bone marrow cells were collected from mice with a C57BL6 genetic background. Cells were differentiated using L929 conditioned media. Cells were assessed using a combination of microscopy, differential staining, immunocytochemistry, and trypan blue. Results: Primary murine BMDMs that underwent cryopreservation followed by resuscitation retained a high degree of viability. Furthermore, these BMDMs retained on overall ability to clear S. aureus. Results. Primary murine BMDMs that underwent cryopreservation followed by resuscitation retained a high degree of viability. Furthermore, these BMDMs retained on overall ability to clear S. aureus. Conclusion. Crypopreserved and resuscitated primary murine BMDMs were viable and retained their pverall S. aureus clearance ability.
Cool semi-arid cropping treatments alter Avena fatua's performance and competitive intensity
(Wiley, 2024-03) Larson, Christian D.; Wong, Mei Long; Carr, Patrick M.; Seipel, Timothy
Introduction. Multiple herbicide-resistant Avena fatua L. is common in the Northern Great Plains, USA. This prevalence and the ecological impacts of tillage in this semi-arid agricultural region have created a need for integrated weed management, with a specific knowledge gap in using annual forage crops and targeted grazing for A. fatua suppression. Materials and Methods. A 2-year study in central Montana, USA, assessed A. fatua performance (aboveground biomass, stem density and seed production) in response to seven cropping treatments: (1–4) tall and short spring wheat cultivars crossed with high and low seeding rates, (5–6) annual forage mixture terminated using sheep grazing and simulated haying and (7) tilled fallow. Avena fatua's competitive intensity in wheat and the annual forage mixture was determined using a relative competition intensity index. Results. Avena fatua performance was lowest in tilled fallow, although stem density and seed production did not differ from the grazed annual forage treatment. Response variables were lower in the forage treatments compared with the wheat treatments, and there were no differences among the four fully crossed wheat treatments. Separate analysis of the wheat treatments indicated lower A. fatua biomass and stem density when wheat was sown at a higher rate with no impact of wheat height. Avena fatua competition impacted wheat and forage crops but was more intense for wheat. Conclusion. Tillage was the most effective treatment at reducing A. fatua performance, but annual forage mixtures can be used to resist A. fatua invasion (reduced A. fatua competitive intensity) and limit its performance after invasion. We conclude that crop sequences that combine higher cash crop (wheat) seeding rates and competitive annual forage mixtures may be utilized to manage A. fatua invaded systems, thereby reducing heavy reliance on tillage in the US Northern Great Plains and similar semi-arid regions.
Dynamical tides during the inspiral of rapidly spinning neutron stars: Solutions beyond mode resonance
(American Physical Society, 2024-07) Yu, Hang; Arras, Phil; Weinberg, Nevin N.
We investigate the dynamical tide in a gravitational wave (GW)-driven coalescing binary involving at least one neutron star (NS). The deformed NS is assumed to spin rapidly, with its spin axis antialigned with the orbit. Such an NS may exist if the binary forms dynamically in a dense environment, and it can lead to a particularly strong tide because the NS f-mode can be resonantly excited during the inspiral. We present a new analytical solution for the f-mode resonance by decomposing the tide into a resummed equilibrium component varying at the tidal forcing frequency and a dynamical component varying at the f-mode eigenfrequency that is excited only around mode resonance. This solution simplifies numerical implementations by avoiding the subtraction of two diverging terms as was done in previous analyses. It also extends the solution’s validity to frequencies beyond mode resonance. When the dynamical tide back reacts on the orbit, we demonstrate that the commonly adopted effective Love number is insufficient because it does not capture the tidal torque on the orbit that dominates the back reaction during mode resonance. An additional dressing factor originating from the imaginary part of the Love number is therefore introduced to model the torque. The dissipative interaction between the NS and the orbital mass multipoles is computed including the dynamical tide and shown to be subdominant compared to the conservative energy transfer from the orbit to the NS modes. Our study shows that orbital phase shifts caused by the 𝑙=3 and 𝑙=2 f-modes can reach 0.5 and 10 radians at their respective resonances if the NS has a spin rate of 850 Hz and direction antialigned with the orbit. Because of the large impact of the 𝑙=2 dynamical tide, a linearized analytical description becomes insufficient, calling for future developments to incorporate higher-order corrections. After mode excitation, the orbit cannot remain quasicircular, and the eccentricity excited by the 𝑙=2 dynamical tide can approach nearly 𝑒≃0.1, leading to nonmonotonic frequency evolution which breaks the stationary phase approximation commonly adopted by frequency domain phenomenological waveform constructions. Lastly, we demonstrate that the GW radiation from the resonantly excited f-mode alone can be detected with a signal-to-noise ratio exceeding unity at a distance of 50 Mpc with the next-generation GW detectors.