Cattle (Bos spp.) grazing on weed–mixed forage biomass may potentially spread weed seeds, leading to plant invasions across pasturelands. Understanding the possibility and intensity of this spread is crucial for developing effective weed control methods in grazed areas. This research undertook an in vitro experiment to evaluate the germination and survival of five dominant weed species in the southern United States [Palmer amaranth (Amaranthus palmeri S. Watson), yellow foxtail [Setaria pumila (Poir.) Roem. & Schult.], johnsongrass [Sorghum halepense (L.) Pers.], field bindweed (Convolvulus arvensis L.) and pitted morningglory (Ipomoea lacunosa L.)] upon incubation in rumen fluid for eight time periods (0, 4, 8, 12, 24, 24, 48, 72, and 96 h). For the 96-h treatment, a full Tilley and Terry procedure was applied after 48 h for stopping fermentation, followed by incubation for another 48 h simulating abomasum digestion. Seed germination, upon incubation, varied significantly among weed species, with I. lacunosa reaching zero germination after only 24 h of incubation, whereas A. palmeri and S. halepense retained up to 3% germination even after 96 h of incubation. The hard seed coats of A. palmeri and S. halepense likely made them highly resistant, whereas the I. lacunosa seed coat became easily permeable and ruptured under rumen fluid incubation. This suggests that cattle grazing can selectively affect seed distribution and invasiveness of weeds in grazed grasslands and rangelands, including the designated invasive and noxious weed species. As grazing is a significant component in animal husbandry, a major economic sector in the U.S. South, our research provides important insights into the potential role of grazing as a dispersal mechanism for some of the troublesome arable weeds in the United States. The results offer opportunities for devising customized feeding and grazing practices combined with timely removal of weeds in grazeable lands at the pre-flowering stage for effective containment of weeds.

The Lower Mekong Basin (LMB) denotes the geographical area that drains into the Mekong River and its tributaries within the Lao PDR, Thailand, Cambodia and Viet Nam. Hydropower development of the LMB’s water resources is proceeding at a rapid pace (Friend, Arthur, & Keskinen, 2009). In addition to 124 hydropower projects at various stages of development, up to twelve mainstream dams are planned for the LMB (ICEM, 2010; MRC, 2010). This large- scale hydro-development involves countless trade-offs of interests, creating clear winners and losers. One of the most significant tradeoffs is that between the ‘traditional’ and ‘modern’ sectors.

Objectives/Goals: We describe the prevalence of individuals with household exposure to SARS-CoV-2, who subsequently report symptoms consistent with COVID-19, while having PCR results persistently negative for SARS-CoV-2 (S[+]/P[-]). We assess whether paired serology can assist in identifying the true infection status of such individuals. Methods/Study Population: In a multicenter household transmission study, index patients with SARS-CoV-2 were identified and enrolled together with their household contacts within 1 week of index’s illness onset. For 10 consecutive days, enrolled individuals provided daily symptom diaries and nasal specimens for polymerase chain reaction (PCR). Contacts were categorized into 4 groups based on presence of symptoms (S[+/-]) and PCR positivity (P[+/-]). Acute and convalescent blood specimens from these individuals (30 days apart) were subjected to quantitative serologic analysis for SARS-CoV-2 anti-nucleocapsid, spike, and receptor-binding domain antibodies. The antibody change in S[+]/P[-] individuals was assessed by thresholds derived from receiver operating characteristic (ROC) analysis of S[+]/P[+] (infected) versusS[-]/P[-] (uninfected). Results/Anticipated Results: Among 1,433 contacts, 67% had ≥1 SARS-CoV-2 PCR[+] result, while 33% remained PCR[-]. Among the latter, 55% (n = 263) reported symptoms for at least 1 day, most commonly congestion (63%), fatigue (63%), headache (62%), cough (59%), and sore throat (50%). A history of both previous infection and vaccination was present in 37% of S[+]/P[-] individuals, 38% of S[-]/P[-], and 21% of S[+]/P[+] (P<0.05). Vaccination alone was present in 37%, 41%, and 52%, respectively. ROC analyses of paired serologic testing of S[+]/P[+] (n = 354) vs. S[-]/P[-] (n = 103) individuals found anti-nucleocapsid data had the highest area under the curve (0.87). Based on the 30-day antibody change, 6.9% of S[+]/P[-] individuals demonstrated an increased convalescent antibody signal, although a similar seroresponse in 7.8% of the S[-]/P[-] group was observed. Discussion/Significance of Impact: Reporting respiratory symptoms was common among household contacts with persistent PCR[-] results. Paired serology analyses found similar seroresponses between S[+]/P[-] and S[-]/P[-] individuals. The symptomatic-but-PCR-negative phenomenon, while frequent, is unlikely attributable to true SARS-CoV-2 infections that go missed by PCR.

The excavation of a stratified sequence of deposits spanning the Initial Late Formative period (250 BC–AD 120) at Iruhito, in the upper Desaguadero Valley of Bolivia, provides insight into this previously unrecognized, four-century period separating the well-documented Middle Formative (800–250 BC) from the Late Formative (~AD 120–590) period. By tracking subtle shifts in ceramic, architectural, lithic, and faunal data, we can explore tempos of change in social life during this dynamic time. These data lead us to suggest that, rather than being a “transitional” period or a “hiatus” in regional occupation, the Initial Late Formative period was a distinct mode of sociality characterized by the realignment and expansion of interaction networks, on the one hand, and rejection of the decorative aesthetics, monumentality, and public-oriented performances of earlier periods, on the other. We argue that the Late Formative period centers emerging after ~AD 120 intentionally cited architecture and aesthetics that were distant in time and space, constituting a sophisticated political strategy. Finally, these data suggest that the chronological schemata we use to build regional histories often obscure social variability.

This article uses tensions over the construction of a flow-regulation infrastructure built to control outflow from Lake Titicaca into the Desaguadero River, on the border between Peru and Bolivia, as a case study to explore the ways that relationships to water emerge and are contested. We argue that a nuanced understanding of tensions arising from this infrastructure requires us to recognize the long-term history of how the river accumulated practices, meanings and materials. Adapting the work of Arturo Escobar, we use the concept of ‘water regime’ to think about how engagements with the river are based in different spatiotemporal frameworks that have developed transhistorically and come into tension around the materiality and dynamism of the river itself.

In order to study the structure and temperature distribution within high-mass star-forming clumps, we employed the Australia Telescope Compact Array to image the $\mathrm{NH}_3$ (J,K) = (1,1) through (6,6) and the (2,1) inversion transitions, the $\mathrm{H}_2\mathrm{O}$ $6_{16}$-$5_{23}$ maser line at 22.23508 GHz, several $\mathrm{CH}_3\mathrm{OH}$ lines and hydrogen and helium recombination lines. In addition, 22- and 24-GHz radio continuum emission was also imaged.

The $\mathrm{NH}_3$ lines probe the optical depth and gas temperature of compact structures within the clumps. The $\mathrm{H}_2\mathrm{O}$ maser pinpoints the location of shocked gas associated with star formation. The recombination lines and the continuum emission trace the ionised gas associated with hot OB stars. The paper describes the data and presents sample images and spectra towards select clumps. The technique for estimating gas temperature from $\mathrm{NH}_3$ line ratios is described. The data show widespread hyperfine intensity anomalies in the $\mathrm{NH}_3$ (1,1) images, an indicator of non-LTE $\mathrm{NH}_3$ excitation. We also identify several new $\mathrm{NH}_3$ (3,3) masers associated with shocked gas. Towards AGAL328.809+00.632, the $\mathrm{H}_2\mathrm{O}$ $6_{16}$-$5_{23}$ line, normally seen as a maser, is instead seen as a thermally excited absorption feature against a strong background continuum. The data products are described in detail.

The conservation sector increasingly values reflexivity, in which professionals critically reflect on the social, institutional and political aspects of their work. Reflexivity offers diverse benefits, from enhancing individual performance to driving institutional transformation. However, integrating reflexivity into conservation practice remains challenging and is often confined to informal reflections with limited impact. To overcome this challenge, we introduce co-reflexivity, offering an alternative to the binary distinction between social science on or for conservation, which respectively produce critical outsider accounts of conservation or provide social science instruments for achieving conservation objectives. Instead, co-reflexivity is a form of social science with conservation, in which conservation professionals and social scientists jointly develop critical yet constructive perspectives on and approaches to conservation. We demonstrate the value of co-reflexivity by presenting a set of reflections on the project model, the dominant framework for conservation funding, which organizes conservation activity into distinct, target-oriented and temporally bounded units that can be funded, implemented and evaluated separately. Co-reflexivity helps reveal the diverse challenges that the project model creates for conservation practice, including for the adoption of reflexivity itself. Putting insights from social science research in dialogue with reflections from conservation professionals, we co-produce a critique of project-based conservation with both theoretical and practical implications. These cross-disciplinary conversations provide a case study of how co-reflexivity can enhance the conservation–social science relationship.

Rift propagation, rather than basal melt, drives the destabilization and disintegration of the Thwaites Eastern Ice Shelf. Since 2016, rifts have episodically advanced throughout the central ice-shelf area, with rapid propagation events occurring during austral spring. The ice shelf's speed has increased by ~70% during this period, transitioning from a rate of 1.65 m d−1 in 2019 to 2.85 m d−1 by early 2023 in the central area. The increase in longitudinal strain rates near the grounding zone has led to full-thickness rifts and melange-filled gaps since 2020. A recent sea-ice break out has accelerated retreat at the western calving front, effectively separating the ice shelf from what remained of its northwestern pinning point. Meanwhile, a distributed set of phase-sensitive radar measurements indicates that the basal melting rate is generally small, likely due to a widespread robust ocean stratification beneath the ice–ocean interface that suppresses basal melt despite the presence of substantial oceanic heat at depth. These observations in combination with damage modeling show that, while ocean forcing is responsible for triggering the current West Antarctic ice retreat, the Thwaites Eastern Ice Shelf is experiencing dynamic feedbacks over decadal timescales that are driving ice-shelf disintegration, now independent of basal melt.

Mica particles approximately 10 or 25 mm square and 0.5 mm thick were placed in NaCl-NaTPB solutions to make visual observations of the changes that occur in micas when the interlayer K is replaced by Na. Samples of muscovite, biotite, phlogopite, lepidolite, and lepidomelane were used, and the effects of different degradation periods were photographed.

An increase in the thickness of the particles due to basal planes splitting apart was observed with all micas. This exfoliation released interlayer K and in some cases caused the particles to cleave into separate flakes. Lepidomelane particles remained intact despite a 20-fold increase in thickness in 7 days. Even muscovite and lepidolite exfoliated and cleaved, but much longer degradation periods were needed.

There was a distinct change in the color of the dark biotite, phlogopite and lepidomelane particles when K was removed. Therefore, the initial stages of K depletion at holes, scratches, and edges of the particles were easily followed. As the degradation of the mica particles progressed, however, the color of the mica became a less reliable index of the stage of K depletion. Visual evidence of K depletion at the edges of particles was also obtained with muscovite, but not with lepidolite.

Transverse sections of 25-mm particles of K-depleted biotite were photographed to show the edge expansion that occurred when interlayer K was replaced by Na.

Interlayer K in muscovite, biotite, phlogopite, illite and vermiculite-hydrobiotite samples was replaced by cation exchange with Na. The rate and amount of exchange varied with the mineral and the level of K in solution.

Essentially, all the K in muscovite, biotite, phlogopite and vermiculite was exchangeable when the mass-action effect of the replaced KT was reduced by maintaining a very low level of K in solution. The time required for this exchange varied from < 10 hr with vermiculite to > 45 weeks with muscovite. Only 66% of the K in the illite was exchangeable under these conditions. When the replaced K was allowed to accumulate in the solution, the amount of exchange was determined by the level of K in solution required for equilibrium. These levels decreased with the degree of K-depletion and with the selectivity of the mica for K. The order of selectivity was muscovite > illite > biotite > phlogopite > vermiculite. Decreasing the K in solution from 10 to 7 ppm increased the exchangeable K in biotite from 30 to 100%. A K level of only 0.1 ppm restricted the exchange of K in muscovite to 17%.

A decrease in layer charge was not required for K exchange, but a decrease did occur in K-depleted biotite and vermiculite. Muscovite with the highest layer charge (247 meq/100 g), least expansion with Na (12.3Å), and least sensitivity to solution pH had the highest selectivity for K and the slowest rate of exchange. The K in vermiculite was the most readily exchangeable.