651 research outputs found
Sedimentology and kinematics of a large, retrogressive growth-fault system in Upper Carboniferous deltaic sediments, western Ireland
Growth faulting is a common feature of many deltaic environments and is vital in determining local sediment dispersal and accumulation, and hence in controlling the resultant sedimentary facies distribution and architecture. Growth faults occur on a range of scales, from a few centimetres to hundreds of metres, with the largest growth faults frequently being under-represented in outcrops that are often smaller than the scale of feature under investigation. This paper presents data from the exceptionally large outcrops of the Cliffs of Moher, western Ireland, where a growth-fault complex affects strata up to 60 m in thickness and extends laterally for 3 km. Study of this Namurian (Upper Carboniferous) growth-fault system enables the relationship between growth faulting and sedimentation to be detailed and permits reconstruction of the kinematic history of faulting. Growth faulting was initiated with the onset of sandstone deposition on a succession of silty mudstones that overlie a thin, marine shale. The decollement horizon developed at the top of the marine shale contact for the first nine faults, by which time aggradation in the hangingwall exceeded 60 m in thickness. After this time, failure planes developed at higher stratigraphic levels and were associated with smaller scale faults. The fault complex shows a dominantly landward retrogressive movement, in which only one fault was largely active at any one time. There is no evidence of compressional features at the base of the growth faults, thus suggesting open-ended slides, and the faults display both disintegrative and non-disintegrative structure. Thin-bedded, distal mouth bar facies dominate the hangingwall stratigraphy and, in the final stages of growth-fault movement, erosion of the crests of rollover structures resulted in the highest strata being restricted to the proximity of the fault. These upper erosion surfaces on the fault scarp developed erosive chutes that were cut parallel to flow and are downlapped by the distal hangingwall strata of younger growth faults
Temperature Range Shifts for Three European Tree Species over the Last 10,000 Years.
We quantified the degree to which the relationship between the geographic distribution of three major European tree species, Abies alba, Fagus sylvatica and Picea abies and January temperature (Tjan) has remained stable over the past 10,000 years. We used an extended data-set of fossil pollen records over Europe to reconstruct spatial variation in Tjan values for each 1000-year time slice between 10,000 and 3000 years BP (before present). We evaluated the relationships between the occurrences of the three species at each time slice and the spatially interpolated Tjan values, and compared these to their modern temperature ranges. Our results reveal that F. sylvatica and P. abies experienced Tjan ranges during the Holocene that differ from those of the present, while A. alba occurred over a Tjan range that is comparable to its modern one. Our data suggest the need for re-evaluation of the assumption of stable climate tolerances at a scale of several thousand years. The temperature range instability in our observed data independently validates similar results based exclusively on modeled Holocene temperatures. Our study complements previous studies that used modeled data by identifying variation in frequencies of occurrence of populations within the limits of suitable climate. However, substantial changes that were observed in the realized thermal niches over the Holocene tend to suggest that predicting future species distributions should not solely be based on modern realized niches, and needs to account for the past variation in the climate variables that drive species ranges
The use of heat and chemical penetration enhancers to increase the follicular delivery of erythromycin to the skin
Copyright © 2019. Published by Elsevier B.V.The effect of heat on the follicular absorption of drugs into the skin has not previously been investigated. In comparison to drug delivery across the continuous stratum corneum (SC), follicular absorption is known to be relatively rapid and therefore the use of short durations of heat may be particularly useful for enhancing drug delivery to the hair follicles, as well as being practical for patients to use. In this study erythromycin has been used as a model drug and the combined use of heat and chemical penetration enhancers was found to be able to synergistically increase the penetration of erythromycin into human skin via the follicular route. Moreover durations of heat application as short as 10 min in combination with particular enhancer systems were found to be sufficient to significantly increase erythromycin delivery to the skin. Overall the data indicate that the use of heat with chemical penetration enhancers offers a potentially valuable strategy for delivering drugs via the follicular route.Peer reviewedFinal Accepted Versio
Radiative Decays of Excited Baryons in the Bound State Picture
It is shown that, in the bound state picture, the and decays are severely
suppressed. On the other hand, for their bottom counterparts, which are
predicted to have masses 5900 and 5926 MeV respectively, may have significant
radiative branching ratio. In particular, the
mode may even dominate over the strong
decay mode. The isospin allowed mode is
expected to be small.Comment: 8 pages in REVTeX, no figure
Timing of HIV testing among pregnant and breastfeeding women and risk of mother-to-child HIV transmission in Malawi: a sampling-based cohort study
Introduction: Pregnant women living with HIV can achieve viral suppression and prevent HIV mother-to-child transmission (MTCT) with timely HIV testing and early ART initiation and maintenance. Although it is recommended that pregnant women undergo HIV testing early in antenatal care in Malawi, many women test positive during breastfeeding because they did not have their HIV status ascertained during pregnancy, or they tested negative during pregnancy but seroconverted postpartum. We sought to estimate the association between the timing of last positive HIV test (during pregnancy vs. breastfeeding) and outcomes of maternal viral suppression and MTCT in Malawi’s PMTCT programme. Methods: We conducted a two-stage cohort study among mother–infant pairs in 30 randomly selected high-volume health facilities across five nationally representative districts of Malawi between 1 July 2016 and 30 June 2017. Log-binomial regression was used to estimate prevalence ratios (PR) and risk ratios (RR) for associations between timing of last positive HIV test (i.e. breastfeeding vs. pregnancy) and maternal viral suppression and MTCT, controlling for confounding using inverse probability weighting. Results: Of 822 mother–infant pairs who had available information on the timing of the last positive HIV test, 102 mothers (12.4%) had their last positive test during breastfeeding. Women who lived one to two hours (PR = 2.15; 95% CI: 1.29 to 3.58) or >2 hours (PR = 2.36; 95% CI: 1.37 to 4.10) travel time to the nearest health facility were more likely to have had their last positive HIV test during breastfeeding compared to women living <1 hour travel time to the nearest health facility. The risk of unsuppressed VL did not differ between women who had their last positive HIV test during breastfeeding versus pregnancy (adjusted RR [aRR] = 0.87; 95% CI: 0.48 to 1.57). MTCT risk was higher among women who had their last positive HIV test during breastfeeding compared to women who had it during pregnancy (aRR = 6.57; 95% CI: 3.37 to 12.81). Conclusions: MTCT in Malawi occurred disproportionately among women with a last positive HIV test during breastfeeding. Testing delayed until the postpartum period may lead to higher MTCT. To optimize maternal and child health outcomes, PMTCT programmes should focus on early ART initiation and providing targeted testing, prevention, treatment and support to breastfeeding women
Scaling in Small-World Resistor Networks
We study the effective resistance of small-world resistor networks. Utilizing
recent analytic results for the propagator of the Edwards-Wilkinson process on
small-world networks, we obtain the asymptotic behavior of the
disorder-averaged two-point resistance in the large system-size limit. We find
that the small-world structure suppresses large network resistances: both the
average resistance and its standard deviation approaches a finite value in the
large system-size limit for any non-zero density of random links. We also
consider a scenario where the link conductance decays as a power of the length
of the random links, . In this case we find that the average
effective system resistance diverges for any non-zero value of .Comment: 15 pages, 6 figure
Migrating Thermal Tides in the Martian Atmosphere During Aphelion Season Observed by EMM/EMIRS
Funding Information: Funding for development of the EMM mission was provided by the United Arab Emirates (UAE) government, and to co‐authors outside of the UAE by the Mohammed bin Rashid Space Centre (MBRSC). RMBY acknowledges funding from UAE University grants G00003322 and G00003407.Peer reviewe
Dynamic Critical Behavior of the Chayes-Machta Algorithm for the Random-Cluster Model. I. Two Dimensions
We study, via Monte Carlo simulation, the dynamic critical behavior of the
Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which
generalizes the Swendsen-Wang dynamics for the q-state Potts ferromagnet to
non-integer q \ge 1. We consider spatial dimension d=2 and 1.25 \le q \le 4 in
steps of 0.25, on lattices up to 1024^2, and obtain estimates for the dynamic
critical exponent z_{CM}. We present evidence that when 1 \le q \lesssim 1.95
the Ossola-Sokal conjecture z_{CM} \ge \beta/\nu is violated, though we also
present plausible fits compatible with this conjecture. We show that the
Li-Sokal bound z_{CM} \ge \alpha/\nu is close to being sharp over the entire
range 1 \le q \le 4, but is probably non-sharp by a power. As a byproduct of
our work, we also obtain evidence concerning the corrections to scaling in
static observables.Comment: LaTeX2e, 75 pages including 26 Postscript figure
Ancient mitochondrial DNA connects house mice in the British Isles to trade across Europe over three millennia.
BACKGROUND: The earliest records in Britain for the western European house mouse (Mus musculus domesticus) date from the Late Bronze Age. The arrival of this commensal species in Britain is thought to be related to human transport and trade with continental Europe. In order to study this arrival, we collected a total of 16 ancient mouse mandibulae from four early British archaeological sites, ranging from the Late Bronze Age to the Roman period. RESULTS: From these, we obtained ancient mitochondrial DNA (mtDNA) house mouse sequences from eight house mice from two of the sites dating from the Late Bronze to Middle Iron Age. We also obtained five ancient mtDNA wood mouse (Apodemus spp.) sequences from all four sites. The ancient house mouse sequences found in this study were from haplogroups E (N = 6) and D (N = 2). Modern British house mouse mtDNA sequences are primarily characterised by haplogroups E and F and, much less commonly, haplogroup D. CONCLUSIONS: The presence of haplogroups D and E in our samples and the dating of the archaeological sites provide evidence of an early house mouse colonisation that may relate to Late Bronze Age/Iron Age trade and/or human expansion. Our results confirm the hypothesis, based on zooarchaeological evidence and modern mtDNA predictions, that house mice, with haplogroups D and E, were established in Britain by the Iron Age and, in the case of haplogroup E, possibly as early as the Late Bronze Age
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