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Known as a bio-limiting metal, high abundances of iron in sea water can amplify biological productivity. The growth of diatoms and other photosynthetic organisms increases, providing more food for grazing organisms like foraminifera. The net result is more organic matter in surface waters and ultimately in surface sediments. Existing satellite data show increases in ocean chlorophyll in areas affected by volcanic eruptions. We infer from this that iron derived from volcanic ash does increase biological productivity. However, the relative increase in productivity is unknown. We examined 3 sediment cores from the Equatorial Western Pacific to analyze the relationship between volcanic ash and biological productivity: RC14-44, RC14-66, and RC14-67. All contain black or dark-colored foraminifera within ash layers and white-shelled foraminifera outside ash layers. We attribute the dark material outside and inside the foraminifera to organic carbon and metals. In our cores, some foraminifera are covered in iron sulfide (FeS), which could be pyrite, and contain large amounts of carbon as well as high abundances of aluminum and silicon. We examined barium concentrations to gain further knowledge of biological productivity at specific core depths as barium is a marker for primary productivity. We found that barium levels within ash layers increased at least ten-fold. Within ash layers, we also noticed that the ashes with higher amounts of fine silt and clay sized material have the greatest increase in barium content, perhaps related to explosion size. This pattern of increases in Ba, metals and organic carbon within ash layers compared to surrounding sediments shows that volcanic ash deposition increases marine productivity. For future research, measuring markers for biological productivity like biogenic silica content and loss on ignition (LOI) within and outside ash layers would further clarify the relationship between volcanic ash deposition and biological productivity. 

Volcanic eruptions deposit Fe-bearing volcanic ash in the ocean, thereby increasing biological productivity. The increased organic matter in areas of high biological productivity uses up oxygen as this organic matter decays and sinks through the water column. Past living beings, like foraminifera, ate organic matter that was carbon-rich and sometimes had metals absorbed into their carbon, creating coatings inside and outside their shells. These coatings can tell us about how biological productivity was affected before, during, and after the volcanic eruption. The studied cores are from the northwest Pacific Ocean and are close to geologically young volcanoes that are not well understood. The two cores that we focused on were VM28-309 and VM36-15 both taken by the Vema research ship. We studied the relationship between ash deposition and biological productivity by looking at all the ash layers in both cores. We found that in most of the ash layers, there were black or dark-colored foraminifera with coatings inside and outside the shells that were often carbon-rich and sometimes metal-rich. We attribute this coating to the increase of organic matter in surface waters when there was deposition of large amounts of volcanic ash. We also found high concentrations of Barium metal in VM28-309. Barium (Ba) is a biological marker because most or all Ba originates from the organic matter contained in sediments. We found that ash layers containing the finest materials (<38 micrometers in size) had the highest Ba content. For accurate results, we must sample above and below ash layers and select more sediment cores in the area. Also, Barium corrections must be done using data on biogenic silica contents. Loss on ignition (LOI) data will give us an estimate of the total organic carbon in each sample- allowing a second direct assessment of the increase in biological productivity produced by the deposition of volcanic ash. 

Some satellite data show an increase in ocean chlorophyll in areas affected by volcanic eruptions. These increases in ocean color are thought to reflect an increase in photosynthetic activity by phytoplankton. These increases in primary production have been attributed to iron (Fe) from volcanic ash, particularly in high-latitude regions where primary productivity is limited by low Fe (the iron fertilization hypothesis). However, photosynthesis also appears to increase in the tropical ocean, for example in the Sunda and Ryukyu arcs and the Bismarck Sea, areas usually not thought to be iron limited. To examine the effects of volcanic ejecta on productivity in other areas, we examine relationships between ash deposition and biological productivity in three cores, RC14-44 (Sunda arc), VM28-309 (Ryukyu arc) and VM33-116 (Bismarck Sea). These cores contain volcanic ash layers with black or dark-colored foraminifera, different from the bright white foraminifera found outside of the ash layers. This dark coloration results primarily from organic carbon. In RC14-44, some foraminifera are coated with FeS and also contain high amounts of internal carbon. In VM28-309 and VM33-116, some foraminifera are filled with organic carbon rich materials, or have coatings rich in carbon. Occasionally, there are local enrichments in Fe within the foraminifera, indicative of extensive redox cycling. We attribute this carbon to increased biological productivity in these intervals. Barium (Ba) concentrations, a proxy for primary productivity because most or all Ba originates from organic matter contained in the sediment, is also enriched by up to 30-fold in the sediments containing ash. The ash layers with the highest amounts of fine material exhibit the largest enrichments in Ba, suggesting ash texture may influence the resulting changes in marine productivity. Overall, we find clear evidence that ash depositions increase both primary production and carbon export to sediments. Loss on ignition (LOI) and biogenic silica contents between and within ash layers, are potentially useful to further examine both the coupling between production and carbon burial, and the influence of ash deposition on phytoplankton community structure. 

Abstract Gut microbiomes, such as the microbial community that colonizes the rumen, have vast catabolic potential and play a vital role in host health and nutrition. By expanding our understanding of metabolic pathways in these ecosystems, we will garner foundational information for manipulating microbiome structure and function to influence host physiology. Currently, our knowledge of metabolic pathways relies heavily on inferences derived from metagenomics or culturing bacteria in vitro. However, novel approaches targeting specific cell physiologies can illuminate the functional potential encoded within microbial (meta)genomes to provide accurate assessments of metabolic abilities. Using fluorescently labeled polysaccharides, we visualized carbohydrate metabolism performed by single bacterial cells in a complex rumen sample, enabling a rapid assessment of their metabolic phenotype. Specifically, we identified bovine-adapted strains of Bacteroides thetaiotaomicron that metabolized yeast mannan in the rumen microbiome ex vivo and discerned the mechanistic differences between two distinct carbohydrate foraging behaviors, referred to as “medium grower” and “high grower.” Using comparative whole-genome sequencing, RNA-seq, and carbohydrate-active enzyme fingerprinting, we could elucidate the strain-level variability in carbohydrate utilization systems of the two foraging behaviors to help predict individual strategies of nutrient acquisition. Here, we present a multi-faceted study using complimentary next-generation physiology and “omics” approaches to characterize microbial adaptation to a prebiotic in the rumen ecosystem. 

We have been studying the stratigraphy of core LWB4-3 taken in 2001 in the Hudson River near Peekskill New York along the transit path of the Peekskill meteorite. We measured magnetic susceptibility at 1 cm intervals down to 108 cm and chemical composition at 1 cm intervals down to 192 cm. The highest magnetic susceptibility occurs at 18 cm depth. This inferred Peekskill meteorite layer with high magnetic susceptibility contains locally higher concentrations of Ni and higher Ni/Cr ratios. Our identification of the high susceptibility, high Ni layer as coming from the fall of the Peekskill meteorite in 1991 is consistent with a uniform sedimentation rate in the core and the occurrence of the base of modern Pb at > 192 cm depth (below the base of the core). From previous work on cores from Central Park Lake, the base of modern Pb represents the year 1880 A.D. We also found other prominent horizons whose ages fit a linear sedimentation rate model. We found a peak in As, whose inferred age matches 1988, the year when Pb and Cu arsenide were banned as pesticides. In addition, we found a modest susceptibility peak above the Peekskill layer whose inferred age matches that of the 1996 Hudson River flood. We found a second modest susceptibility peak below the Peekskill layer whose inferred age matches that of the "Great Catskill Toilet Flush Flood" in 1980. This layer also has local maxima in Pb, Cu and Ca. The Catskills contain Devonian limestone that might be the source of excess Ca. Copper Mine brook is located on the east bank of the Hudson north of Peekskill and is a potential source of Cu during floods. Our core exhibits a distinct increase in Ca content starting at 20 cm depth and increasing towards the top of the core. This prominent increase in Ca may represent 1991 A.D, the time of the invasion of the zebra mussel. We are testing this depth range for calcium carbonate to determine if the upward calcium increase could be from the invasion of the zebra mussel, increased soil erosion or anthropogenic pollution. We found a peak in Pb at 112 cm depth whose inferred age matches that of the cessation of incinerator burning in 1938. Cs-137 and Pb-210 ages are in progress and may be available by the time of the meeting. We also saw an unusual horizon at a depth of 118 cm with a high peak of Cr. This would be approximately the year 1936, which corresponds to a large flood in the Hudson. 

We have been studying the stratigraphy of core LWB 4-5 taken in 2001 in the Hudson River 1.5 km north of the transit of the Peekskill meteorite in October 1992. We measured magnetic susceptibility and elemental composition at 1 cm intervals down to 50 cm and then at 5 cm intervals down to 108 cm. Magnetic susceptibilities are unusually high (above 20 cgs units) from 12-19 cm and again at 31 cm. The level at 31 cm contains mm-sized fragments of Fe oxide. X-Ray Fluorescence spectroscopy revealed high Ni/Cr levels concentrated from 9-11 cm and again below 97 cm. We found tektite-like spheroids, dumbbells and teardrops from 8-15 cm depth. They are glasses and they contain appreciable K, consistent with an origin as true tektites but we have not identified the source. Overall, we interpret the high susceptibility, high Ni/Cr and possibly tektite bearing layer as a resulting from the fall of one of the bodies postulated to have fallen with the Peekskill meteorite in 1992. A 1992 age for the top of the Peekskill layer at 8-9 cm depth is consistent with a uniform sedimentation rate in the core and the occurrence of the base of modern Pb at 97 cm depth. From previous work on cores from Central Park Lake, the base of modern Pb represents the year 1880 A.D. We also found other prominent horizons whose ages fit a linear sedimentation rate model. We found a step change in As/Pb ratio whose inferred age matches 1988, the year when Pb and Cu arsenide were banned as pesticides. Our core exhibits peaks in Ca and Sr content and a minor susceptibility peak at 17.5 depth that may represent the 1980 "Great Catskill Toilet Flush" Hudson River flood event. The Catskills contain abundant marine limestone that could serve as a source for Ca and Sr. A prominent susceptibility peak at 37.5 cm could represent a flood in 1955. We also found a peak in Pb at 50 cm depth whose inferred age matches that of the cessation of incinerator burning in 1938. 137Cs and 210Pb ages are in progress and may be available by the time of the meeting. The high Pb and As levels in parts of LWB 4-5 are supported by examination of the coarse fraction. We found two bright orange grains, both with carbon rich coatings. One grain analyses on the X-ray analyzer of an SEM as 8%C, 70% Pb, 17%As and 2% Cu. The second grain analyzes as 10% C, 43% Pb, 1% Ca, 2% P, 27% As, 4% Fe, 2% Ni, 1% Si, and 6% Zn. All analyses are in wt.% on an oxygen free basis. 

We have been studying the stratigraphy of core LWB4-1 taken in 2001 in the Hudson River about 100 meters north of the calculated transit path of the Peekskill meteorite in October 1992. We measured magnetic susceptibility at 1cm intervals from 0 -70 cm depth and found a layer with a magnetic susceptibility of 11 cgs units at 6 cm depth. This is the highest susceptibility in the top 40 cm of the core. Scanning X-Ray Fluorescence spectroscopy revealed the high susceptibility layer at 6 cm depth is part of a 3 cm interval with a high Ni/Cr ratio, but the depth of the peak in the Ni/Cr ratio is poorly resolved due to measurement error. We plan to dry and homogenize discreet samples for analysis on bench top XRF to reduce Ni and Cr error. Based on our identification of the base of modern Pb at 68 cm depth, the top 40 cm of the core covers the time interval from 2001 to 1930. From previous work on Central Park Lake, the base of modern Pb represents the year 1880 A.D. A uniform sedimentation rate model is supported a peak in Pb and As at 8 cm depth. The peak might represent the 1988 ban on the use of Pb arsenide and the start of use of DDT as a pesticide. We found a second peak in Pb at 37.5cm potentially from 1938, the date at which incineration was banned in New York City. We found a third peak in Pb at 50.5cm that might be from World War I around 1914. We found two deeper susceptibility peaks of 12 cgs at 43 cm and 8 cgs at 59 cm. These peaks could represent major Hudson River floods in 1927 and 1903. 137Cs and 210Pb 210 dating are in progress and will help us to determine if our age model is correct. Also, our core exhibits a distinct increase in Ca content starting at 18-25 cm depth and increasing towards the top of the core. This increase could be due to increased erosion, anthropogenic inputs or increased dissolution of CaCO3 rich rocks. We are measuring CaCO3 in the core to better determine the origin of this increase of Ca. 

Abstract A search for leptoquark pair production decaying into$$te^- \bar{t}e^+$$ $t{e}^{-}\overline{t}{e}^{+}$or$$t\mu ^- \bar{t}\mu ^+$$ $t{\mu }^{-}\overline{t}{\mu }^{+}$in final states with multiple leptons is presented. The search is based on a dataset ofppcollisions at$$\sqrt{s}=13~\text {TeV} $$ $\sqrt{s}=13\text{TeV}$recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$$^{-1}$$ $_{}^{-1}$. Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from ab-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into$$te^{-}$$ $t{e}^{-}$($$t\mu ^{-}$$ $t{\mu }^{-}$), the corresponding lower limit on the scalar mixed-generation leptoquark mass$$m_{\textrm{LQ}_{\textrm{mix}}^{\textrm{d}}}$$ $m_{{\text{LQ}}_{\text{mix}}^{\text{d}}}$is at 1.58 (1.59) TeV and on the vector leptoquark mass$$m_{{\tilde{U}}_1}$$ $m_{{\tilde{U}}_1}$at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario. 

A search for high-mass resonances decaying into a $\tau$-lepton and a neutrino using proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$is presented. The full run 2 data sample corresponding to an integrated luminosity of $139{\mathrm{fb}}^{-1}$recorded by the ATLAS experiment in the years 2015–2018 is analyzed. The $\tau$-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between the $\tau$-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on the $W^{\prime }\to \tau \nu$production cross section. Heavy $W^{\prime }$vector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard Model $W$boson. For nonuniversal couplings, $W^{\prime }$bosons are excluded for masses less than 3.5–5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of the $\tau$-lepton and missing transverse momentum. © 2024 CERN, for the ATLAS Collaboration2024CERN