New geochemical data, including Sr–Nd–Pb isotopes for whole-rock and groundmass samples, are reported for edifice-forming eruptives at Tongariro volcano, New Zealand, which span its ~ 350 ka to late ...Holocene history. Tongariro eruptives are medium-K basaltic-andesites to dacites (53.0–66.2 wt% SiO
2
) that evolved via assimilation-fractional crystallisation (AFC) processes partly or mostly in the uppermost 15 km of the crust. When ordered chronologically using a high-resolution
40
Ar/
39
Ar-dated eruptive stratigraphy, the compositional data show systematic 10–130 kyr cycles. Mafic replenishment events inferred from MgO values occurred at ~ 230, ~ 151, ~ 88 and ~ 56 ka and in the late Holocene, with high-MgO flank vents erupting at ~ 160, ~ 117, ~ 35 and ~ 17.5 ka. Cycles in Sm/Nd,
87
Sr/
86
Sr,
143
Nd/
144
Nd and Pb isotopic ratios, which are decoupled from MgO, K
2
O and Rb/Sr cycles, indicate periods of prolonged crustal residence of magmas from ~ 230 to ~ 100 ka and ~ 95 to ~ 30 ka. AFC modelling shows that intermediate and silicic melt compositions, with r-values between 0.1 and 1, are needed to reproduce Tongariro compositional arrays. AFC models also indicate that ~ 20% of the average Tongariro magma comprises assimilated (meta)sedimentary basement material. Locally, Tongariro and adjacent Ruapehu volcanoes attain their most crust-like
87
Sr/
86
Sr and
143
Nd/
144
Nd compositions at ~ 100 and ~ 30 ka, paralleling with zircon model-age crystallisation modes at the rhyolitic Taupō volcano ~ 50 km to the NNE. These coincidences suggest that the timing and tempo of magma assembly processes at all three volcanoes were contemporaneous and may have been tectonically influenced since at least 200 ka.
Planning Virtual Science Fairs WILSON, COLIN P.
Science scope (Washington, D.C.),
01/2022, Letnik:
45, Številka:
3
Journal Article
Recenzirano
The explicit function of a science fair, submission of a final product, can be achieved easily, but what likely gives many would-be virtual fair directors pause are the implicit expectations that are ...part of a fair experience. In our years of experience, a lack of quality feedback is the factor that elicits the most negative responses from students and parents. * Students expect to receive results and prizes. Judges reported their assessments using a Google Form rubric (shown in Figure 2 with a link in Online Resources), which fed automatically into a spreadsheet, and category judges reported the special award winners through a shared document. Per the baseline guidelines, these videos should cover the same information as an oral presentation during an in-person fair, whatever is required by your fair's rules. Because of the medium, though, there are other considerations students may have when they are being recorded.
Future of Venus Research and Exploration Glaze, Lori S.; Wilson, Colin F.; Zasova, Liudmila V. ...
Space science reviews,
08/2018, Letnik:
214, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Despite the tremendous progress that has been made since the publication of the Venus II book in 1997, many fundamental questions remain concerning Venus' history, evolution and current geologic and ...atmospheric processes. The international science community has taken several approaches to prioritizing these questions, either through formal processes like the Planetary Decadal Survey in the United States and the Cosmic Vision in Europe, or informally through science definition teams utilized by Japan, Russia, and India. These questions are left to future investigators to address through a broad range of research approaches that include Earth-based observations, laboratory and modeling studies that are based on existing data, and new space flight missions. Many of the highest priority questions for Venus can be answered with new measurements acquired by orbiting or in situ missions that use current technologies, and several plausible implementation concepts have been studied and proposed for flight. However, observations needed to address some science questions pose substantial technological challenges, for example, long term survival on the surface of Venus and missions that require surface or controlled aerial mobility. Missions enabled by investments in these technologies will open the door to completely new ways of exploring Venus to provide unique insights into Venus's past and the processes at work today.
Effective transvascular delivery of nanoparticle-based chemotherapeutics across the blood-brain tumor barrier of malignant gliomas remains a challenge. This is due to our limited understanding of ...nanoparticle properties in relation to the physiologic size of pores within the blood-brain tumor barrier. Polyamidoamine dendrimers are particularly small multigenerational nanoparticles with uniform sizes within each generation. Dendrimer sizes increase by only 1 to 2 nm with each successive generation. Using functionalized polyamidoamine dendrimer generations 1 through 8, we investigated how nanoparticle size influences particle accumulation within malignant glioma cells.
Magnetic resonance and fluorescence imaging probes were conjugated to the dendrimer terminal amines. Functionalized dendrimers were administered intravenously to rodents with orthotopically grown malignant gliomas. Transvascular transport and accumulation of the nanoparticles in brain tumor tissue was measured in vivo with dynamic contrast-enhanced magnetic resonance imaging. Localization of the nanoparticles within glioma cells was confirmed ex vivo with fluorescence imaging.
We found that the intravenously administered functionalized dendrimers less than approximately 11.7 to 11.9 nm in diameter were able to traverse pores of the blood-brain tumor barrier of RG-2 malignant gliomas, while larger ones could not. Of the permeable functionalized dendrimer generations, those that possessed long blood half-lives could accumulate within glioma cells.
The therapeutically relevant upper limit of blood-brain tumor barrier pore size is approximately 11.7 to 11.9 nm. Therefore, effective transvascular drug delivery into malignant glioma cells can be accomplished by using nanoparticles that are smaller than 11.7 to 11.9 nm in diameter and possess long blood half-lives.
Plasmodial Kinase Inhibitors: License to Cure? Cabrera, Diego González; Horatscheck, André; Wilson, Colin R ...
Journal of medicinal chemistry,
09/2018, Letnik:
61, Številka:
18
Journal Article
Recenzirano
Odprti dostop
Advances in the genetics, function, and stage-specificity of Plasmodium kinases has driven robust efforts to identify targets for the design of antimalarial therapies. Reverse genomics following ...phenotypic screening against Plasmodia or related parasites has uncovered vulnerable kinase targets including PI4K, PKG, and GSK-3, an approach bolstered by access to human disease-directed kinase libraries. Alternatively, screening compound libraries against Plasmodium kinases has successfully led to inhibitors with antiplasmodial activity. As with other therapeutic areas, optimizing compound ADMET and PK properties in parallel with target inhibitory potency and whole cell activity becomes paramount toward advancing compounds as clinical candidates. These and other considerations will be discussed in the context of progress achieved toward deriving important, novel mode-of-action kinase-inhibiting antimalarial medicines.
The Auckland Volcanic Field (AVF), which last erupted ca. 550years ago, is a late Quaternary monogenetic basaltic volcanic field (ca. 500km2) in the northern North Island of New Zealand. Prior to ...this study only 12 out of the 53 identified eruptive centres of the AVF had been reliably dated. Careful sample preparation and 40Ar/39Ar analysis has increased the number of well-dated centres in the AVF to 35. The high precision of the results is attributed to selection of fresh, non-vesicular, non-glassy samples from lava flow interiors. Sample selection was coupled with separation techniques that targeted only the groundmass of samples with <5% glass and with groundmass feldspars >10μm wide, coupled with ten-increment furnace step-heating of large quantities (up to 200mg) of material. The overall AVF age data indicate an onset at 193.2±2.8ka, an apparent six-eruption flare-up from 30 to 34ka, and a ≤10kyr hiatus between the latest and second-to-latest eruptions. Such non-uniformity shows that averaging the number of eruptions over the life-span of the AVF to yield a mean eruption rate is overly simplistic. Together with large variations in eruption volumes, and the large sizes and unusual chemistry within the latest eruptions (Rangitoto 1 and Rangitoto 2), our results illuminate a complex episodic eruption history. In particular, the rate of volcanism in AVF has increased since 60ka, suggesting that the field is still in its infancy. Multiple centres with unusual paleomagnetic inclination and declination orientations are confirmed to fit into a number of geomagnetic excursions, with five identified in the Mono Lake, two within the Laschamp, one within the post-Blake or Blake, and two possibly within the Hilina Pali.
•Particular selection, preparation & analysis yield precise ages on young basalts.•The number of accurately dated volcanoes has increased from 12 to 35 out of 53.•The rate of volcanism in the field has increased since 60ka.•The post-60ka record is complex, leading to ambiguities in likelihood forecasting.•The new data allow re-analysis of volcanoes within four geomagnetic excursions.
Background
Chemotherapy-associated liver injury is a major cause for concern when treating patients with colorectal liver metastases. The aim of this review was to determine the pathological effect ...of specific chemotherapy regimens on the hepatic parenchyma as well as on surgical morbidity, mortality and overall survival.
Methods
A systematic review of the published literature and a meta-analysis were performed. For each of the variables under consideration, the effects of different chemotherapy regimens were determined by calculation of relative risks by a random-effects model.
Results
Hepatic parenchymal injury is regimen specific, with oxaliplatin-based regimens being associated with grade 2 or greater sinusoidal injury (number needed to harm 8; 95 % confidence interval CI 6.4–13.6), whereas irinotecan-based regimens associated with steatohepatitis (number needed to harm 12; 95 % CI 7.8–26). The use of bevacizumab alongside FOLFOX reduces the risk of grade 2 or greater sinusoidal injury (relative risk 0.34; 95 % CI 0.15–0.75).
Conclusions
Chemotherapy before resection of colorectal liver metastases is associated with an increased risk of regimen-specific liver injury. This liver injury may have implications for the functional reserve of the liver for patients undergoing major hepatectomy for colorectal liver metastases.
The Taupo Volcanic Zone (TVZ) in the central North Island of New Zealand lies across the boundary formed in the late Mesozoic between two major basement regions: the Waipapa and Torlesse composite ...terranes. However, the precise location of this terrane contact within the TVZ is not well constrained because it is buried beneath Pleistocene volcanic and volcaniclastic sequences locally >3 km thick. Here we report new U-Pb zircon detrital age spectra from basement sandstones and younger Waikora Formation greywacke gravel from five geothermal well core samples and one surface sample. We combine these new data with existing TVZ zircon xenocryst and xenolith age spectra from volcanic host rocks, to correlate these materials with each basement terrane and constrain the likely spatial location and uncertainty of the terrane boundary under the TVZ. Its position with respect to surficial geothermal systems suggests that, at depth, the terrane boundary may have been reactivated by Quaternary extension in the evolving Taupo Rift. Put another way, the past and current position of the Taupo Rift fundamentally may have been controlled by the terrane boundary, which may ultimately be partly responsible for providing enhanced fracture permeability for deep-seated geothermal fluids.
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