176 research outputs found
Renewing the Exploration Approach for Mid-Enthalpy Systems: Examples from Northern England and Scotland
After a promising start in the 1970s and 80s, the UK rather fell behind other countries in the search for viable mid-enthalpy
geothermal resources. This situation began to turn around in 2004, when the first of three deep geothermal exploration boreholes
were drilled in northern England. What distinguished these from earlier drilling in Cornwall was the deliberate search for naturallyhigh
permeability associated with major faults, especially those that have undergone strike-slip reactivation during the Cenozoic.
Boreholes at Eastgate in the North Pennines targeted buried radiothermal granite, whereas the 1,821m-deep Science Central
Borehole in Newcastle upon Tyne targeted a postulated deep sedimentary aquifer (the Fell Sandstones), which were inferred to be
connected laterally to the granitic heat source by a major fault (the reactivation of the Iapetus geo-suture). The drilling was in both
cases rewarded with impressive heat flows, and in the case of Eastgate with what is believed to be the highest permeability yet
found in a deep granite batholith anywhere in the world. In parallel with these developments, a re-assessment was made of the preexisting
geothermal heat flow database for the UK, applying newly-standardised correction protocols for palaeoclimatic and
topographic distortions, which were found to be particularly marked in Scotland (where only shallow boreholes had been used to
establish geothermal gradients in the original 1980s analysis), Similar prospects in northern England (similar to that drilled at
Science Central) are now the focus of commercial exploration efforts. Appraisal of fault dispositions relative to the present-day
maximum compressive stress azimuth are being used to identify the most promising areas for intersecting fault-related permeability
at depth. New geophysical tools – most notably atomic dielectric resonance scanning – are also being appraised for their ability to
directly detect features (such as hot brines) which are indicative of localised convection in target fault zones and aquifers
Seasonal total methane depletion in limestone caves
Methane concentration in caves is commonly much lower than the external atmosphere, yet the cave CH4 depletion causal mechanism is contested and dynamic links to external diurnal and seasonal temperature cycles unknown. Here, we report a continuous 3-year record of cave methane and other trace gases in Jenolan Caves, Australia which shows a seasonal cycle of extreme CH4 depletion, from ambient ∼1,775 ppb to near zero during summer and to ∼800 ppb in winter. Methanotrophic bacteria, some newly-discovered, rapidly consume methane on cave surfaces and in external karst soils with lifetimes in the cave of a few hours. Extreme bacterial selection due to the absence of alternate carbon sources for growth in the cave environment has resulted in an extremely high proportion 2-12% of methanotrophs in the total bacteria present. Unexpected seasonal bias in our cave CH4 depletion record is explained by a three-step process involving methanotrophy in aerobic karst soil above the cave, summer transport of soil-gas into the cave through epikarst, followed by further cave CH4 depletion. Disentangling cause and effect of cave gas variations by tracing sources and sinks has identified seasonal speleothem growth bias, with implied palaeo-climate record bias
Google haul out : Earth observation imagery and digital aerial surveys in coastal wildlife management and abundance estimation
© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bioscience 67 (2017): 760–768, doi:10.1093/biosci/bix059.As the sampling frequency and resolution of Earth observation imagery increase, there are growing opportunities for novel applications in population monitoring. New methods are required to apply established analytical approaches to data collected from new observation platforms (e.g., satellites and unmanned aerial vehicles). Here, we present a method that estimates regional seasonal abundances for an understudied and growing population of gray seals (Halichoerus grypus) in southeastern Massachusetts, using opportunistic observations in Google Earth imagery. Abundance estimates are derived from digital aerial survey counts by adapting established correction-based analyses with telemetry behavioral observation to quantify survey biases. The result is a first regional understanding of gray seal abundance in the northeast US through opportunistic Earth observation imagery and repurposed animal telemetry data. As species observation data from Earth observation imagery become more ubiquitous, such methods provide a robust, adaptable, and cost-effective solution to monitoring animal colonies and understanding species abundances.We would like to thank generous support from International Fund for Animal Welfare, the Bureau of Ocean Energy, and the Oak Foundation for funding support for the telemetry devices
Origin and History of Mitochondrial DNA Lineages in Domestic Horses
Domestic horses represent a genetic paradox: although they have the greatest number of maternal lineages (mtDNA) of all domestic species, their paternal lineages are extremely homogeneous on the Y-chromosome. In order to address their huge mtDNA variation and the origin and history of maternal lineages in domestic horses, we analyzed 1961 partial d-loop sequences from 207 ancient remains and 1754 modern horses. The sample set ranged from Alaska and North East Siberia to the Iberian Peninsula and from the Late Pleistocene to modern times. We found a panmictic Late Pleistocene horse population ranging from Alaska to the Pyrenees. Later, during the Early Holocene and the Copper Age, more or less separated sub-populations are indicated for the Eurasian steppe region and Iberia. Our data suggest multiple domestications and introgressions of females especially during the Iron Age. Although all Eurasian regions contributed to the genetic pedigree of modern breeds, most haplotypes had their roots in Eastern Europe and Siberia. We found 87 ancient haplotypes (Pleistocene to Mediaeval Times); 56 of these haplotypes were also observed in domestic horses, although thus far only 39 haplotypes have been confirmed to survive in modern breeds. Thus, at least seventeen haplotypes of early domestic horses have become extinct during the last 5,500 years. It is concluded that the large diversity of mtDNA lineages is not a product of animal breeding but, in fact, represents ancestral variability
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Myocardial Infarction Accelerates Atherosclerosis
During progression of atherosclerosis, myeloid cells destabilize lipid-rich plaque in the arterial wall and cause its rupture, thus triggering myocardial infarction and stroke. Survivors of acute coronary syndromes have a high risk of recurrent events for unknown reasons. Here we show that the systemic response to ischemic injury aggravates chronic atherosclerosis. After myocardial infarction or stroke, apoE mice developed larger atherosclerotic lesions with a more advanced morphology. This disease acceleration persisted over many weeks and was associated with markedly increased monocyte recruitment. When seeking the source of surplus monocytes in plaque, we found that myocardial infarction liberated hematopoietic stem and progenitor cells from bone marrow niches via sympathetic nervous system signaling. The progenitors then seeded the spleen yielding a sustained boost in monocyte production. These observations provide new mechanistic insight into atherogenesis and provide a novel therapeutic opportunity to mitigate disease progression
Tumour regression and improved gastrointestinal tolerability from controlled release of SN-38 from novel polyoxazoline-modified dendrimers
Irinotecan is used clinically for the treatment of colorectal cancer; however, its utility is limited by its narrow therapeutic index. We describe the use of a generation 5 l-lysine dendrimer that has been part-modified with a polyoxazoline as a drug delivery vehicle for improving the therapeutic index of SN-38, the active metabolite of irinotecan. By conjugating SN-38 to the dendrimer via different linker technologies we sought to vary the release rate of the drug to generate diverse pharmacokinetic profiles. Three conjugates with plasma release half-lives of 2.5 h, 21 h, and 72 h were tested for efficacy and toxicity using a mouse SW620 xenograft model. In this model, the linker with a plasma release half-life of 21 h achieved sustained SN-38 exposure in blood, above the target concentration. Control over the release rate of the drug from the linker, combined with prolonged circulation of the dendrimer, enabled administration of an efficacious dose of SN-38, achieving significant regression of the SW620 tumours. The conjugates with 2.5 and 72 h release half-lives did not achieve an anti-tumour effect. Intraperitoneal dosing of the clinically used prodrug irinotecan produces high initial and local concentrations of SN-38, which are associated with gastrointestinal toxicity. Administration of the 21 h release dendrimer conjugate did not produce a high initial Cmax of SN-38. Consequently, a marked reduction in gastrointestinal toxicity was observed relative to irinotecan treatment. Additional studies investigating the dose concentrations and dose scheduling showed that a weekly dosing schedule of 4 mg SN-38/kg was the most efficacious regimen. After 4 doses at weekly intervals, the survival period of the mice extended beyond 70 days following the final dose. These extensive studies have allowed us to identify a linker, dose and dosing regimen for SN-38 conjugated to polyoxazoline-modified dendrimer that maximised efficacy and minimised adverse side effects
Molecular Insights into the Pathogenesis of Alzheimer's Disease and Its Relationship to Normal Aging
Alzheimer's disease (AD) is a complex neurodegenerative disorder that diverges from the process of normal brain aging by unknown mechanisms. We analyzed the global structure of age- and disease-dependent gene expression patterns in three regions from more than 600 brains. Gene expression variation could be almost completely explained by four transcriptional biomarkers that we named BioAge (biological age), Alz (Alzheimer), Inflame (inflammation), and NdStress (neurodegenerative stress). BioAge captures the first principal component of variation and includes genes statistically associated with neuronal loss, glial activation, and lipid metabolism. Normally BioAge increases with chronological age, but in AD it is prematurely expressed as if some of the subjects were 140 years old. A component of BioAge, Lipa, contains the AD risk factor APOE and reflects an apparent early disturbance in lipid metabolism. The rate of biological aging in AD patients, which cannot be explained by BioAge, is associated instead with NdStress, which includes genes related to protein folding and metabolism. Inflame, comprised of inflammatory cytokines and microglial genes, is broadly activated and appears early in the disease process. In contrast, the disease-specific biomarker Alz was selectively present only in the affected areas of the AD brain, appears later in pathogenesis, and is enriched in genes associated with the signaling and cell adhesion changes during the epithelial to mesenchymal (EMT) transition. Together these biomarkers provide detailed description of the aging process and its contribution to Alzheimer's disease progression
THE RADIAL AND ROTATIONAL VELOCITIES OF PSO J318.5338-22.8603, A NEWLY CONFIRMED PLANETARY-MASS MEMBER OF THE β PICTORIS MOVING GROUP
PSO J318.533822.8603 is an extremely-red planetary-mass object that has
been identified as a candidate member of the Pictoris moving group
based on its spatial position and tangential velocity. We present a high
resolution -band spectrum of PSO J318.533822.8603. Using a
forward-modeling Markov Chain Monte Carlo approach, we report the first
measurement of the radial velocity and sin() of PSO J318.522,
6.0 km s and 17.5 km s,
respectively. We calculate the space velocity and position of PSO J318.522
and confirm that it is a member of the Pictoris moving group. Adopting
an age of 233 Myr for PSO J318.522, we determine a mass of
and effective temperature of K using
evolutionary models. PSO J318.533822.8603 is intermediate in mass and
temperature to the directly-imaged planets Pictoris b and 51 Eridani b,
making it an important benchmark object in the sequence of planetary-mass
members of the Pictoris moving group. Combining our sin()
measurement with recent photometric variability data, we constrain the
inclination of PSO J318.522 to and its rotational period to
5-10.2 hours. The equatorial velocity of PSO J318.522 indicates that its
rotation is consistent with an extrapolation of the velocity-mass relationship
for solar system planets.Comment: 8 pages, 5 figures, 2 tables, ApJ accepte
Is Aboriginal Food Less Allergenic? Comparing IgE-Reactivity of Eggs from Modern and Ancient Chicken Breeds in a Cohort of Allergic Children
BACKGROUND: Hen's egg allergy ranks among the most frequent primary food allergies in children. We aimed to investigate sensitization profiles of egg allergic patients and compare in vitro IgE reactivities of eggs from ancient chicken breeds (Araucana and Maran) with those from conventional laying hen hybrids. METHODOLOGY: Egg allergic children (n = 25) were subjected to skin prick test, double blind placebo controlled food challenge, and sensitization profiles to Gal d 1-5 were determined by allergen microarray. IgE binding and biological activity of eggs from different chicken breeds were investigated by immunoblot, ELISA, and mediator release assays. PRINCIPAL FINDINGS: We found that Gal d 1 and Gal d 2 are generally major egg allergens, whereas Gal d 3-5 displayed high sensitization prevalence only in patients reacting to both, egg white and yolk. It seems that the onset of egg allergy is mediated by egg white allergens expanding to yolk sensitization in later stages of disease. Of note, egg white/yolk weight ratios were reduced in eggs from Auraucana and Maran chicken. As determined in IgE immunoblots and mass analysis, eggs from ancient chicken breeds did not differ in their protein composition. Similar IgE-binding was observed for all egg white preparations, while an elevated allergenicity was detected in egg yolk from Araucana chicken. CONCLUSION/SIGNIFICANCE: Our results on allergenicity and biological activity do not confirm the common assumption that aboriginal food might be less allergenic. Comprehensive diagnosis of egg allergy should distinguish between reactivity to hen's egg white and yolk fractions to avoid unnecessary dietary restrictions to improve life quality of the allergic child and its family
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