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Surface mass balance (SMB) is the net input of mass on a glacier's upper surface, composed of snow deposition, melt and erosion processes, and is a major contributor to the overall mass balance. Pine Island Glacier (PIG) in West Antarctica has been dynamically imbalanced since the early 1990s, indicating that discharge of solid ice into the oceans exceeds snow deposition. However, observations of the SMB pattern on the fast flowing regions are scarce, and are potentially affected by the firn's strain history. Here, we present new observations from radar-derived stratigraphy and a relatively dense network of firn cores, collected along a ~900 km traverse of PIG. Between 1986 and 2014, the SMB along the traverse was 0.505 m w.e. a−1 on average with a gradient of higher snow deposition in the South-West compared with the North-East of the catchment. We show that along ~80% of the traverse the strain history amounts to a misestimation of SMB below the nominal uncertainty, but can exceed it by a factor 5 in places, making it a significant correction to the SMB estimate locally. We find that the strain correction changes the basin-wide SMB by ~0.7 Gt a−1 and thus forms a negligible (1%) correction to the glacier's total SMB.
A national need is to prepare for and respond to accidental or intentional disasters categorized as chemical, biological, radiological, nuclear, or explosive (CBRNE). These incidents require specific subject-matter expertise, yet have commonalities. We identify 7 core elements comprising CBRNE science that require integration for effective preparedness planning and public health and medical response and recovery. These core elements are (1) basic and clinical sciences, (2) modeling and systems management, (3) planning, (4) response and incident management, (5) recovery and resilience, (6) lessons learned, and (7) continuous improvement. A key feature is the ability of relevant subject matter experts to integrate information into response operations. We propose the CBRNE medical operations science support expert as a professional who (1) understands that CBRNE incidents require an integrated systems approach, (2) understands the key functions and contributions of CBRNE science practitioners, (3) helps direct strategic and tactical CBRNE planning and responses through first-hand experience, and (4) provides advice to senior decision-makers managing response activities. Recognition of both CBRNE science as a distinct competency and the establishment of the CBRNE medical operations science support expert informs the public of the enormous progress made, broadcasts opportunities for new talent, and enhances the sophistication and analytic expertise of senior managers planning for and responding to CBRNE incidents.
Invasive rodents detrimentally affect native bird species on many islands worldwide, and rodent eradication is a useful tool to safeguard endemic and threatened species. However, especially on tropical islands, rodent eradications can fail for various reasons, and it is unclear whether the temporary reduction of a rodent population during an unsuccessful eradication operation has beneficial effects on native birds. Here we examine the response of four endemic land bird species on subtropical Henderson Island in the Pitcairn Island Group, South Pacific Ocean, following an unsuccessful rodent eradication in 2011. We conducted point counts at 25 sampling locations in 14 survey periods between 2011 and 2015, and modelled the abundance trends of all species using binomial mixture models accounting for observer and environmental variation in detection probability. Henderson Reed Warbler Acrocephalus taiti more than doubled in abundance (2015 population estimate: 7,194-28,776), and Henderson Fruit Dove Ptilinopus insularis increased slightly between 2011 and 2015 (2015 population estimate: 4,476–10,072), while we detected no change in abundance of the Henderson Lorikeet Vini stepheni (2015 population estimate: 554–3014). Henderson Crake Zapornia atra increased to pre-eradication levels following anticipated mortality during the operation (2015 population estimate: 4,960–20,783). A temporary reduction of rat predation pressure and rat competition for fruit may have benefitted the reed warbler and the fruit dove, respectively. However, a long drought may have naturally suppressed bird populations prior to the rat eradication operation in 2011, potentially confounding the effects of temporary rat reduction and natural recovery. We therefore cannot unequivocally ascribe the population recovery to the temporary reduction of the rat population. We encourage robust monitoring of island biodiversity both before and after any management operation to better understand responses of endemic species to failed or successful operations.
Since I agree with Schulting’s conclusions, my comments consist mostly of suggestions for further work that he could do, for example further issues that he might want to look into and passages that might give him trouble. One such issue is what is now sometimes called the Localization Problem: if the mind supplies temporal and (where present) spatial organization and most (at least most) conceptual structure to the manifold of intuition, what could be used to place bits of the manifold at one place rather than another, to determine that this concept rather than that applies, and the like? I urge that this in fact a very serious problem for Kant. Among passages that might create a problem for Schulting’s reading, I focus on the Refutation of Idealism, which Kant added to the second (B-)edition.
We present techniques for obtaining large (∼100 L STP) samples of ancient air for analysis of 14C of methane (14CH4)and other trace constituents. Paleoatmospheric 14CH4 measurements should constrain the fossil fraction of past methane budgets, as well as provide a definitive test of methane clathrate involvement in large and rapid methane concentration ([CH4]) increases that accompanied rapid warming events during the last deglaciation. Air dating to the Younger Dryas–Preboreal and Oldest Dryas–Bølling abrupt climatic transitions was obtained by melt extraction from old glacial ice outcropping at an ablation margin in West Greenland. The outcropping ice and occluded air were dated using a combination of δ15N of N2, δ18O of O2, δ18Oice and [CH4] measurements. The [CH4] blank of the melt extractions was <4 ppb. Measurements of δ18O and δ15N indicated no significant gas isotopic fractionation from handling. Measured Ar/N2, CFC-11 and CFC-12 in the samples indicated no significant contamination from ambient air. Ar/N2, Kr/Ar and Xe/Ar ratios in the samples were used to quantify effects of gas dissolution during the melt extractions and correct the sample [CH4]. Corrected [CH4] is elevated over expected values by up to 132 ppb for most samples, suggesting some in situ CH4 production in ice at this site.
The recent revelation that there are correlated period derivative and pulse shape changes in pulsars has dramatically changed our understanding of timing noise as well as the relationship between the radio emission and the properties of the magnetosphere as a whole. Using Gaussian processes we are able to model timing and emission variability using a regression technique that imposes no functional form on the data. We revisit the pulsars first studied by Lyne et al. (2010). We not only confirm the emission and rotational transitions revealed therein, but reveal further transitions and periodicities in 8 years of extended monitoring. We also show that in many of these objects the pulse profile transitions between two well-defined shapes, coincident with changes to the period derivative. With a view to the SKA and other telescopes capable of higher cadence we also study the detection limitations of period derivative changes.
We present a new method developed for measuring radiocarbon of methane (14CH4) in ancient air samples extracted from glacial ice and dating 11,000–15,000 calendar years before present. The small size (∼20 μg CH4 carbon), low CH4 concentrations ([CH4], 400–800 parts per billion [ppb]), high carbon monoxide concentrations ([CO]), and low 14C activity of the samples created unusually high risks of contamination by extraneous carbon. Up to 2500 ppb CO in the air samples was quantitatively removed using the Sofnocat reagent. 14C procedural blanks were greatly reduced through the construction of a new CH4 conversion line utilizing platinized quartz wool for CH4 combustion and the use of an ultra-high-purity iron catalyst for graphitization. The amount and 14C activity of extraneous carbon added in the new CH4 conversion line were determined to be 0.23 ± 0.16 μg and 23.57 ± 16.22 pMC, respectively. The amount of modern (100 pMC) carbon added during the graphitization step has been reduced to 0.03 μg. The overall procedural blank for all stages of sample handling was 0.75 ± 0.38 pMC for ∼20-μg, 14C-free air samples with [CH4] of 500 ppb. Duration of the graphitization reactions for small (<25 μg C) samples was greatly reduced and reaction yields improved through more efficient water vapor trapping and the use of a new iron catalyst with higher surface area. 14C corrections for each step of sample handling have been determined. The resulting overall 14CH4 uncertainties for the ancient air samples are ∼1.0 pMC.
In what sense might nature based tourism be considered education for sustainability? “Educational” confers an implied worthiness which may seem to offset the environmental costs of tourism. Moreover, nature-based tourism may indeed have an important educational role to play. This paper examines the role of “education” in ecotourism discourse, and argues that a predominance in ecotourism of an overly simplified set of educational concepts. These fail to convince that “educational” nature based tourism provides a significant contribution to education for sustainability, and equally fail to establish the necessity for tourism as a means to those educatonal ends which are achieved. The paper concludes with a discussion of some of the considerations which a more serious consideration of nature based tourism as education would have to take into account.
The fourth season of the Fezzan Project continued the interdisciplinary approaches of previous seasons. Geographical and environmental work focused principally in sampling sediments for scientific dating and with integrating ground observation with remote sensing data. Excavations continued at Old Germa, where the site has now reached Garamantian levels. In a separate development, the tentative identification has been made of an early mosque at the site, in an area adjacent to the G1 excavation trench. Substantial results were gained from work aimed at enhancing the important data recorded by Charles Daniels in his earlier excavations and survey in the Wadi al-Hayat. The enhancement of the Daniels' survey archive was integrated with completion of the wider prospection being undertaken by the new project. This survey included fieldwalking, standing building survey, analysis of the foggara irrigation systems and recording of rock art scenes. Finds work comprised the finalisation of a pottery type series for the Germa area, the study of small finds from the recent survey work, botanical analysis and completion of lithics recording. A programme of radiocarbon dating is now being undertaken to improve the phasing of sites and monuments. The first two volumes of final reports are now in preparation.
Monozygotic (MZ) twins are genetically identical at conception, making them informative subjects for studies on somatic mutations. Copy number variants (CNVs) are responsible for a substantial part of genetic variation, have relatively high mutation rates, and are likely to be involved in phenotypic variation. We conducted a genome-wide survey for post-twinning de novo CNVs in 1,097 MZ twin pairs. Comparisons between MZ twins were made by CNVs measured in DNA from blood or buccal epithelium with the Affymetrix 6.0 microarray and two calling algorithms. In addition, CNV concordance rates were compared between the different sources of DNA, and gene-enrichment association analyses were conducted for thought problems (TP) and attention problems (AP) using CNVs concordant within MZ pairs. We found a total of 153 putative post-twinning de novo CNVs >100 kb, of which the majority resided in 15q11.2. Based on the discordance of raw intensity signals a selection was made of 20 de novo CNVs for a qPCR validation experiments. Two out of 20 post-twinning de novo CNVs were validated with qPCR in the same twin pair. The 13-year-old MZ twin pair that showed two discordances in CN in 15q11.2 in their buccal DNA did not show large phenotypic differences. From the remaining 18 putative de novo CNVs, 17 were deletions or duplications that were concordant within MZ twin pairs. Concordance rates within twin pairs of CNV calls with CN ≠ 2 were ~80%. Buccal epithelium-derived DNA showed a slightly but significantly higher concordance rate, and blood-derived DNA showed significantly more concordant CNVs per twin pair. The gene-enrichment analyses on concordant CNVs showed no significant associations between CNVs overlapping with genes involved in neuronal processes and TP or AP after accounting for the source of DNA.
We give a sharper version of a theorem of Rosický, Trnková and Adámek , and a new proof of a theorem of Rosický , both about colimits in categories of structures. Unlike the original proofs, which use category-theoretic methods, we use set-theoretic arguments involving elementary embeddings given by large cardinals such as α-strongly compact and C(n)-extendible cardinals.