639 research outputs found

    Mercury in tundra vegetation of Alaska: Spatial and temporal dynamics and stable isotope patterns

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    Vegetation uptake of atmospheric mercury (Hg) is an important mechanism enhancing atmospheric Hg deposition via litterfall and senescence. We here report Hg concentration and pool sizes of different plant functional groups and plant species across nine tundra sites in northern Alaska. Significant spatial differences were observed in bulk vegetation Hg concentrations at Toolik Field station (52 ± 9â€ŻÎŒg kg−1), Eight Mile Lake Observatory (40 ± 0.2â€ŻÎŒg kg−1), and seven sites along a transect from Toolik Field station to the Arctic coast (36 ± 9â€ŻÎŒg kg−1). Hg concentrations in non-vascular vegetation including feather and peat moss (58 ± 6â€ŻÎŒg kg−1 and 34 ± 2â€ŻÎŒg kg−1, respectively) and brown and white lichen (41 ± 2â€ŻÎŒg kg−1 and 34 ± 2â€ŻÎŒg kg−1, respectively), were three to six times those of vascular plant tissues (8 ± 1â€ŻÎŒg kg−1 in dwarf birch leaves and 9 ± 1â€ŻÎŒg kg−1 in tussock grass). A high representation of nonvascular vegetation in aboveground biomass resulted in substantial Hg mass contained in tundra aboveground vegetation (29â€ŻÎŒg m−2), which fell within the range of foliar Hg mass estimated for forests in the United States (15 to 45â€ŻÎŒg m−2) in spite of much shorter growing seasons. Hg stable isotope signatures of different plant species showed that atmospheric Hg(0) was the dominant source of Hg to tundra vegetation. Mass-dependent isotope signatures (ÎŽ202Hg) in vegetation relative to atmospheric Hg(0) showed pronounced shifts towards lower values, consistent with previously reported isotopic fractionation during foliar uptake of Hg(0). Mass-independent isotope signatures (Δ199Hg) of lichen were more positive relative to atmospheric Hg(0), indicating either photochemical reduction of Hg(II) or contributions of inorganic Hg(II) from atmospheric deposition and/or dust. Δ199Hg and Δ200Hg values in vascular plant species were similar to atmospheric Hg(0) suggesting that overall photochemical reduction and subsequent re-emission was relatively insignificant in these tundra ecosystems, in agreement with previous Hg(0) ecosystem flux measurements

    Improving immersive experiences for visitors with sensory impairments to the aquarium of the pacific

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    This case study describes the development of a mid-air haptic solution to enhance the immersive experience of visitors who are deaf, blind or wheelchair users to the Aquarium of the Pacific's movie theatre. During the project we found that adding a sense of touch, using an innovative ultrasound technology, to an immersive experience can improve the sense of engagement users have with the content, and can help to improve agreement with the topics presented. We present guidelines on the design of haptic sensations. By describing how this project took place within the tight timelines of a commercial deployment, we hope to encourage more organisations to do similar work

    Timing of Deformation along the Iron Springs Thrust, Southern Sevier Fold-and-Thrust Belt, Utah: Evidence for an Extensive Thrusting Event in the mid-Cretaceous

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    The temporal and spatial distribution of strain associated with the Sevier orogeny in western North America is significantly different in the southern end of the belt, at the latitude of Las Vegas, Nevada, than farther to the north at the latitude of Salt Lake City, Utah. Reasons for these differences have been speculative as a lack of temporal constraints on thrusting in the intervening region hindered along-strike correlation across the belt. We determined a crystallization age of 100.18 ± 0.04 Ma for zircons extracted from a recently recognized dacite lapilli ash-fall tuff near the base of the synorogenic Iron Springs Formation. We propose the name “Three Peaks Tuff Member” for this unit, and identify a type stratigraphic section on the western flank of the “Three Peaks,” a topographic landmark in Iron County, Utah. Field relationships and this age constrain movement on the Iron Springs thrust and the end of the sub-Cretaceous unconformity in the critical intervening area to latest Albian/earliest Cenomanian. Movement on the Iron Springs thrust was synchronous with movement on multiple Sevier thrusts at ~100 Ma, indicating that the mid-Cretaceous was a period of extensive thrust-fault movement. This mid-Cretaceous thrusting event coincided with a period of global plate reorganization and increased convergence, and hence an increased subduction rate for the Farallon Plate beneath North America. The accelerated subduction contributed to a Cordilleran arc flare-up event and steepening of the orogenic wedge, which triggered widespread thrusting across the retroarc Sevier deformation belts. Additionally, based on temporal constraints and the strong spatial connection of mid-Cretaceous thrusts to lineaments interpreted as pre-orogenic transform faults, we suggest that temporal and spatial variations along the strike of the orogenic belt reflect tectonic inheritance of basement structures associated with the edge of the rifted Precambrian craton

    Low copy expression vectors for use in Yersinia sp. and related organisms

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    In Yersinia, the most commonly used expression vectors for genetic studies such as gene complementation do not effectively allow for both induction and repression of gene expression. Additionally, there is no expression system available that can be induced in bacteria growing in vitro as well as in vivo, e.g. in eukaryotic cell lines or in living animal models. Here, we present a series of novel inducible low copy expression vectors that are well suited for use in the Yersinia species. Their tet operator/promoter/repressor system makes them distinct from other vectors, and gene transcription in bacteria can easily be induced by addition of anhydrotetracyline (ATc) either to the growth medium, to tissue culture medium during bacterial infections of cell lines or by injection into animals infected with bacteria. Researchers can choose between two different antibiotic resistances (kanamycin or spectinomycin), between two copy numbers (5 or 12-22) as well as between two different versions for expression from either the native RBS and ATG or RBS and ATG encoded in the plasmid. The whole vector series contains the same multi-cloning site from pBluescript II KS+ that allows for easy subcloning. Moreover, these vectors are built in a modular fashion that makes it simple to adapt them for other purposes. Finally, in addition to their use in Yersinia they are suitable for use in many other Enterobacteriaceae

    The YsrS Paralog DygS Has the Capacity To Activate Expression of the Yersinia enterocolitica Ysa Type III Secretion System

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    ABSTRACT The Yersinia enterocolitica Ysa type III secretion system (T3SS) is associated with intracellular survival, and, like other characterized T3SSs, it is tightly controlled. Expression of the ysa genes is only detected following growth at low temperatures (26°C) and in high concentrations of sodium chloride (290 mM) in the medium. The YsrSTR phosphorelay (PR) system is required for ysa expression and likely responds to NaCl. During our investigations into the Ysr PR system, we discovered that genes YE3578 and YE3579 are remarkably similar to ysrR and ysrS , respectively, and are probably a consequence of a gene duplication event. The amino acid differences between YE3578 and ysrR are primarily clustered into two short regions. The differences between YE3579 and ysrS are nearly all located in the periplasmic sensing domain; the cytoplasmic domains are 98% identical. We investigated whether these paralogs were capable of activating ysa gene expression. We found that the sensor paralog, named DygS, is capable of compensating for loss of ysrS , but the response regulator paralog, DygR, cannot complement a ysrR gene deletion. In addition, YsrR, but not DygR, interacts with the histidine phosphorelay protein YsrT. Thus, DygS likely activates ysa gene expression in response to a signal other than NaCl and provides an example of a phosphorelay system in which two sensor kinases feed into the same regulatory pathway. IMPORTANCE All organisms need mechanisms to promote survival in changing environments. Prokaryotic phosphorelay systems are minimally comprised of a histidine kinase (HK) that senses an extracellular stimulus and a response regulator (RR) but can contain three or more proteins. Through gene duplication, a unique hybrid HK was created. We show that, while the hybrid appears to retain all of the phosphorelay functions, it responds to a different signal than the original. Both HKs transmit the signal to the same RR, which activates a promoter that transcribes a set of genes encoding a type III secretion system (T3SS) whose function is not yet evident. The significance of this work lies in finding that two HKs regulate this T3SS, highlighting its importance

    Mapping FoodHCI Futures

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    Recognizing the significant potential impact that HCI has on food practices and experiences, researchers and practitioners are undertaking a growing number of explorations of novel computing technology and food combinations. These explorations have so far primarily emphasized technology-driven systems and taken a human-centric perspective. We propose a Special Interest Group (SIG) in "foodHCI futures"that creates a space for researchers to discuss the boundaries of food incorporating HCI, and with the simultaneous aims of reconciling food with technology and extending our visions for human-food interactions towards anthropocentrism. Specifically, the SIG will be a beginning of developing a structured conceptual map of the possibilities for future technology interventions in food systems. In developing this map, we hope to encourage democratized debate, provoke new and divergent thoughts on the opportunities for foodHCI, and ultimately gain unique insights that contribute to preferable food futures

    BPPV: Comparison of the SĂ©montPLUS With the SĂ©mont Maneuver: A Prospective Randomized Trial

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    Objective: To compare the efficacy of the SĂ©mont maneuver (SM) with the new “SĂ©montPLUS maneuver” (SM+) in patients with posterior canal BPPV canalolithiasis (pcBPPVcan). Methods and Patients: In a prospective trinational (Germany, Italy, and Belgium) randomized trial, patients with pcBPPVcan were randomly assigned to SM or SM+; SM+ means overextension of the head by 60+° below earth horizontal line during the movement of the patient toward the affected side. The first maneuver was done by the physician, and the subsequent maneuvers by the patients 9 times/day on their own. Each morning the patient documented whether vertigo could be induced. The primary endpoints were: “How long (in days) does it take until no attacks can be induced?” and “What is the efficacy of a single SM/SM+?” Results: In the 194 patients analyzed (96 SM, 98 SM+), it took 2 days (median, range 1–21 days, mean 3.6 days) for recovery with SM and 1 day (median, range 1-8 days, mean 1.8 days) with SM+ (p = 0.001, Mann-Whitney U-test). There was no difference in the second primary endpoint (chi2-test, p = 0.39). Interpretation: This prospective trial shows that SM+ is more effective than SM when repeated therapeutic maneuvers are performed but not when a single maneuver is performed. It also supports the hypothesis of the biophysical model: overextension of the head during step 2 brings the clot of otoconia beyond the vertex of the canal, which increases the effectivity. Classification of Evidence: This study provides Class I evidence that SM+ is superior to SM for multiple treatment maneuvers of pcBPPVcan. © The Author

    Reproducibility and its confounders of CMR feature tracking myocardial strain analysis in patients with suspected myocarditis.

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    OBJECTIVES Cardiovascular magnetic resonance feature tracking (CMR-FT) is an emerging technique for assessing myocardial strain with valuable diagnostic and prognostic potential. However, the reproducibility of biventricular CMR-FT analysis in a large cardiovascular population has not been assessed. Also, evidence of confounders impacting reader reproducibility for CMR-FT in patients is unknown and currently limits the clinical implementation of this technique. METHODS From a dual-center database of patients referred to CMR for suspected myocarditis, 125 patients were randomly selected to undergo biventricular CMR-FT analysis for 2-dimensional systolic and diastolic measures, with additional 3-dimensional analysis for the left ventricle. All image analysis was replicated by a single reader and by a second reader for intra- and inter-reader analysis (Circle Cardiovascular Imaging). Reliability was tested with intraclass correlation (ICC) tests, and the impact of imaging confounders on agreement was assessed through multivariable analysis. RESULTS Left and right ventricular ejection fractions were reduced in 34% and 37% of the patients, respectively. Good to excellent reliability was shown for 2D (all ICC > 0.85) and 3D (all ICC > 0.70) peak strain and early diastolic strain rate for both ventricles in longitudinal orientation as well as circumferential orientations for the left ventricle. An increased slice number improved agreement while the presence of pericardial effusion compromised diastolic strain rate agreement, and arrhythmia compromised right ventricular agreement. CONCLUSION In a large clinical cohort, we could show CMR-FT yields excellent inter-reader and intra-reader reproducibility. Multi-parametric CMR-FT of the right and left ventricles appears to be a robust tool in cardiovascular patients referred to CMR. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03470571, NCT04774549. Key Points ‱ Cardiovascular magnetic resonance feature tracking (CMR-FT) is an emerging technique to measure myocardial strain in cardiovascular patients referred for CMR; however, the evaluation of its reproducibility in a large cohort has not yet been performed. ‱ In a large clinical cohort, CMR-FT yields excellent inter-reader and intra-reader reproducibility for both left and right ventricular systolic and diastolic parameters. ‱ Arrhythmia and pericardial effusion compromise agreement of select FT parameters, but poor ejection fraction does not
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