2,838 research outputs found
Major disruption of D″ beneath Alaska
D″ represents one of the most dramatic thermal and compositional layers within our planet. In particular, global tomographic models display relatively fast patches at the base of the mantle along the circum-Pacific which are generally attributed to slab debris. Such distinct patches interact with the bridgmanite (Br) to post-bridgmanite (PBr) phase boundary to generate particularly strong heterogeneity at their edges. Most seismic observations for the D″ come from the lower mantle S wave triplication (Scd). Here we exploit the USArray waveform data to examine one of these sharp transitions in structure beneath Alaska. From west to east beneath Alaska, we observed three different characteristics in D″: (1) the western region with a strong Scd, requiring a sharp δVs = 2.5% increase; (2) the middle region with no clear Scd phases, indicating a lack of D″ (or thin Br-PBr layer); and (3) the eastern region with strong Scd phase, requiring a gradient increase in δVs. To explain such strong lateral variation in the velocity structure, chemical variations must be involved. We suggest that the western region represents relatively normal mantle. In contrast, the eastern region is influenced by a relic slab that has subducted down to the lowermost mantle. In the middle region, we infer an upwelling structure that disrupts the Br-PBr phase boundary. Such an interpretation is based upon a distinct pattern of travel time delays, waveform distortions, and amplitude patterns that reveal a circular-shaped anomaly about 5° across which can be modeled synthetically as a plume-like structure rising about 400 km high with a shear velocity reduction of ~5%, similar to geodynamic modeling predictions of upwellings
Superparasitism and Population Regulation of the Mosquito-Parasitic Mermithid Nematodes Romanomermis iyengari and Strelkovimermis spiculatus
Superparasitism is a common phenomenon in mosquito-parasitic mermithid nematodes. Multiple nematodes are needed in a single host to produce males. Host selection behavior and intraspecific competition among Romanomermis iyengari and Strelkovimermis spiculatus were investigated against their host, Culex pipiens pipiens in laboratory experiments. In a choice assay between previously infected and uninfected host larvae, infectious preparasites of both nematode species could distinguish not only between infected and uninfected hosts, but even between different parasite loads in showing a strong preference for uninfected hosts or hosts with a low parasite load. Host heart rate declined briefly immediately after parasitism. Superparasitism resulted in increased parasite mortality. Scramble competition within mosquito larvae for limited host nutrients, coupled with a skewed sex ratio favoring males, is assumed to lead to parasite population decline and subsequently toward host-parasite population equilibrium. The ability of mermithid preparasites to accurately assess parasite load likely plays an important role in host population dynamics and regulation
Perturbation of gene expression of the chromatin remodeling pathway in premature newborns at risk for bronchopulmonary dysplasia
The expression profiles of umbilical cords from premature newborns reveal distinct patterns, including changes in the expression of chromatin remodeling factors, associated with the development of bronchopulmonary dysplasia
Implementation of an Evidence-Based intervention With Safety Net Clinics to Improve Mammography appointment adherence among Underserved Women
The Peace of Mind Program is an evidence-based intervention to improve mammography appointment adherence in underserved women. The aim of this study was to assess effectiveness of the intervention and implementation of the intervention in safety net clinics. The intervention was implemented through a non-randomized stepped wedge cluster hybrid study design with 19 Federally Qualified Health Centers and charity care clinics within the Greater Houston area. A multivariable generalized estimating equation logistic regression was conducted to examine mammography appointment adherence. A survey assessing Consolidated Framework for Implementation Research constructs was also conducted with clinic staff prior to adoption and eight weeks post implementation. One-sided t-tests were conducted to analyze mean score changes between the surveys. A total of 4402 women (baseline period = 2078; intervention period = 2324) were included in the final regression analysis. Women in the intervention period were more likely to attend or reschedule their mammography appointment (OR = 1.30; p \u3c 0.01) than those in the baseline period receiving usual care. Women who completed the intervention were more likely to attend or reschedule their mammography appointment than those who did not complete the intervention (OR = 1.62; p \u3c 0.01). The mammography appointment no-show rates for those in the baseline period, in the intervention period, and who completed the intervention were, respectively, 22%, 19%, and 15%. A total of 15 clinics prior to adoption and eight clinics completed the survey at 8 weeks post implementation A statistically significant mean score decrease was observed in Inner Setting and in two Inner Setting CFIR constructs, Culture-Effort, and Implementation Climate. While the intervention improved mammography appointment adherence, there are opportunities to further integrate Consolidated Framework for Implementation Research constructs. Trial registration: Clinical trials registration number: NCT02296177
Habitat Features Predict the Distribution of Recreational Shooters in the Morley Nelson Snake River Birds of Prey National Conservation Area
The Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) is a popular destination of many Treasure Valley residents. There, recreationists participate in various pastimes such as target shooting, recreational shooting/hunting, and wildlife viewing. However, these activities have the potential to interfere with one another. Recreational shooting of Piute ground squirrels (Urocitellus mollis) could affect prey availability and scavenging opportunities for associated raptor species, most notably local golden eagle (Aquila chrysaetos) populations. To assess possible interactions among shooters, prey and raptors, the spatial density and habitat preference of human shooters must be determined. We hypothesized that higher shooter density would be correlated with proximity to high-use roads and habitat with high visibility. To test this hypothesis, the spatial density and habitat preference of human shooters was determined. First, three routes of approximately 16 km each were established throughout the northwest section of the NCA through “hunter hotspots” of various habitat types. Routes were driven on weekends, starting in the morning, from February 28 to March 21, 2015. Data was collected opportunistically on all shooters observed including group size, demographics, location, and the habitat characteristics (e.g. proximity to roads and visibility) of shooting sites. These data were used to determine which habitat features best predicted shooting locations. This study may directly inform future research on golden eagle scavenging ecology, competition between hunters and eagles, and the potential for lead entry into the ecosystem through use of lead ammunition
Does Personality Affect the Probability That Piute Ground Squrriels (\u3cem\u3eUrocitellus Mollis\u3c/em\u3e) Will Be Shot by Recreational Hunters?
Recreational shooting of Piute ground squirrels (Urocitellus mollis) in southern Idaho is an activity growing in popularity. One factor that may influence shooting success is the personality of individuals within a population. We hypothesized that bold individual ground squirrels would be more/less likely to be targeted by a hunter and would be more/less disturbed by gun fire. To test these hypotheses, we simulated recreational shooting to identify which personalities are more susceptible hunters and more responsive to gun fire. We preformed simulations in March of 2015 on a population of Piute ground squirrels with known personalities. Bold and shy individuals were coded by dying the fur of squirrels in a way distinguishable by observers during simulations which took place at three sites with varying vegetative cover. We recorded the frequency of detection of each personality type through a hunting scope. In addition, we observed the behavioral response (e.g. flee, vigilance, alarm call) of ground squirrels to a recording of a .22 caliber fire. We also identified whether raptors were attracted to the simulated shooting area for scavenging in response to the sound of the gun fire. We calculated whether the detection and behavioral responses of squirrel personalities in shooting simulations was disproportionate to that of the marked population. This information can lead to a greater understanding of the role of behavioral factors in the survival of Piute ground squirrels and provide insight into how recreational shooting could influence the personality landscape of a dominant prey species
Natural isoforms of the Photosystem II D1 subunit differ in photoassembly efficiency of the water-oxidizing complex
© 2015 Springer Science+Business Media Dordrecht. Oxygenic photosynthesis efficiency at increasing solar flux is limited by light-induced damage (photoinhibition) of Photosystem II (PSII), primarily targeting the D1 reaction center subunit. Some cyanobacteria contain two natural isoforms of D1 that function better under low light (D1:1) or high light (D1:2). Herein, rates and yields of photoassembly of the Mn4CaO5 water-oxidizing complex (WOC) from the free inorganic cofactors (Mn2+, Ca2+, water, electron acceptor) and apo-WOC-PSII are shown to differ significantly: D1:1 apo-WOC-PSII exhibits a 2.3-fold faster rate-limiting step of photoassembly and up to seven-fold faster rate to the first light-stable Mn3+ intermediate, IM1, but with a much higher rate of photoinhibition than D1:2. Conversely, D1:2 apo-WOC-PSII assembles slower but has up to seven-fold higher yield, achieved by a higher quantum yield of charge separation and slower photoinhibition rate. These results confirm and extend previous observations of the two holoenzymes: D1:2-PSII has a greater quantum yield of primary charge separation, faster [P680+ Q A- ] charge recombination and less photoinhibition that results in a slower rate and higher yield of photoassembly of its apo-WOC-PSII complex. In contrast, D1:1-PSII has a lower quantum yield of primary charge separation, a slower [P680+ Q A- ] charge recombination rate, and faster photoinhibition that together result in higher rate but lower yield of photoassembly at higher light intensities. Cyanobacterial PSII reaction centers that contain the high- and low-light D1 isoforms can tailor performance to optimize photosynthesis at varying light conditions, with similar consequences on their photoassembly kinetics and yield. These different efficiencies of photoassembly versus photoinhibition impose differential costs for biosynthesis as a function of light intensity
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