730 research outputs found

    Programmatic efficiency comparisons between unequally sized groups of DMUs in DEA

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    Data envelopment analysis (DEA) is a popular non-parametric technique for determining the efficiency of a homogeneous set of decision-making units (DMUs). In many practical cases, there is some doubt if the all the DMUs form a single group with a common efficiency distribution. The Mann-Whitney rank statistic has been used in DEA both to test if two groups of DMUs come from a common efficiency distribution and also to test if the two groups have a common frontier, each of which are likely to have important but different policy implications for the management of the groups. In this paper it is demonstrated that where the Mann-Whitney rank statistic is used for the second of these it is likely to overestimate programmatic inefficiency, particularly of the smaller group. A new non-parametric statistic is proposed for the case of comparing the efficient frontiers of two groups, which overcomes the problems we identify in the use of the Mann-Whitney rank statistic for this purpose. © 2005 Operational Research Society Ltd. All rights reserved

    Geochemical constraints on basalt petrogenesis in the Strait of Sicily Rift Zone (Italy): Insights into the importance of short lengthscale mantle heterogeneity

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    Igneous activity from the late Miocene to historic time (most recently 1891 CE) in the Strait of Sicily has created two volcanic islands (Pantelleria and Linosa) and several seamounts. These volcanoes are dominated by transitional (ol + hy-normative) to alkaline (ne-normative) basaltic lavas and scoriae; volcanic felsic rocks (peralkaline trachyte-rhyolite) crop out only on Pantelleria. Although most likely erupted through continental crust, basalts demonstrate no evidence of crustal contamination and are geochemically similar to oceanic island basalts (OIB). Despite their isotopic similarities, there are considerable compositional differences with respect to major and trace element geochemistry both between and within the two islands that are due to short-length scale mantle heterogeneity beneath the region as well as variability in partial melting and magma storage conditions. Published geophysical surveys suggest that lithospheric thickness beneath both islands is ~60 km; this is consistent with the results of our geochemical modelling (59\u201360 km), which also suggest mantle potential temperatures between 1415 and 1435 \ub0C, similar to those documented in other continental passive rifts. Trace element and isotopic data reveal that the asthenosphere beneath the Strait of Sicily is heterogenous at both interisland (100s of km) and intra-island (10s of km) scales. Although there is some compositional overlap between the two major synthems at Linosa, in general the older magmas (Arena Bianca, 700 ka) formed as a result of ~5% partial melting of a depleted MORB mantle (DMM) source enriched with a relatively small amount of recycled MORB material, whereas the younger magmas (Monte Bandiera, 530 ka) formed as a result of ~2% partial melting of a similar mantle source. Pantelleria magmas formed from a higher degree (~6%) of partial melting of a DMM source with a relatively greater amount of recycled MORB material and possibly other components. Geochemical modelling also suggests the older magmas on Linosa differentiated at a much shallower level (~8 km) than the younger magmas (~25 km, at or below the base of the crust) prior to eruption. Magmas stored in higher-level reservoirs were effectively homogenized and preserve a narrower compositional range than magmas sourced from depth. Data for the seamounts are scarce and compromised by significant seawater alteration; thus, these volcanic centers cannot be modelled but based on comparative geochemistry with the islands are likely the result of even smaller (< 2%) degrees of partial melting beneath thicker (> 60 km) lithosphere. Despite the geophysical similarities between the two islands in terms of lithospheric thickness and crustal thinning, melt productivity has been greater at Pantelleria, producing a much larger island and sustaining felsic magmatism, which we hypothesize may ultimately be entirely due to the local occurrence of much more fusible mantle

    Geochemical Constraints on Mantle Sources and Basalt Petrogenesis in the Strait of Sicily Rift Zone (Italy): Insights into the Importance of Short Lengthscale Mantle Heterogeneity.

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    Igneous activity from the late Miocene to historic time (most recently 1891 ce) in the Strait of Sicily has created two islands (Pantelleria and Linosa) and several seamounts. These volcanoes are dominated by transitional (ol+hy-normative) to alkaline (ne-normative) basaltic lavas and scoriae; peralkaline felsic rocks (trachyte-rhyolite) crop out only on Pantelleria. Although most likely erupted through continental crust, basalts demonstrate no evidence of crustal contamination and are geochemically similar to oceanic island basalts (OIB). Despite their isotopic similarities, there are considerable compositional differences with respect to major and trace element geochemistry both between and within the two islands that are due to short-length scale mantle heterogeneity beneath the region as well as variability in partial melting and magma storage conditions. Published geophysical surveys suggest that lithospheric thickness beneath both islands is ~60 km; this is consistent with the results of our geochemical modelling (59-60 km), which also suggest mantle potential temperatures between 1415-1435°C, similar to other documented continental passive rifts. Although there is some compositional overlap between the three synthems at Linosa, in general the older magmas (Arena Bianca, 700 ka) formed as a result of ~5% partial melting of a depleted MORB mantle (DMM) source enriched with a relatively small amount of recycled MORB material, which differentiated in a shallow-level (~8 km) magma chamber prior to eruption whereas the younger magmas (Monte Bandiera, 530 ka) formed as a result of ~2% partial melting of a similar mantle source, which differentiated in a magma chamber at or below the base of the crust (~25 km). Pantelleria magmas formed from a higher degree (~6%) of partial melting of a DMM source enriched with a relatively greater amount of recycled MORB material with possibly other components. Data for the seamounts are scarce and compromised by significant seawater alteration; thus, these volcanic centers cannot be modelled but based on comparative geochemistry with the islands are likely the result of even smaller (60 km) lithosphere. Magmas stored in the higher-level chamber were more effectively homogenized and preserve a narrower compositional range. Despite the geophysical similarities between the two islands in terms of lithospheric thickness and crustal thinning, melt productivity has been greater at Pantelleria, producing a much larger island and sustaining felsic magmatism, which may ultimately be entirely due to the local occurrence of much more fusible mantle

    Differential specificity between closely related corals and abundant Endozoicomonas endosymbionts across global scales

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    © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The ISME Journal 11 (2017): 186–200, doi:10.1038/ismej.2016.95.Reef-building corals are well regarded not only for their obligate association with endosymbiotic algae, but also with prokaryotic symbionts, the specificity of which remains elusive. To identify the central microbial symbionts of corals, their specificity across species and conservation over geographic regions, we sequenced partial SSU ribosomal RNA genes of Bacteria and Archaea from the common corals Stylophora pistillata and Pocillopora verrucosa across 28 reefs within seven major geographical regions. We demonstrate that both corals harbor Endozoicomonas bacteria as their prevalent symbiont. Importantly, catalyzed reporter deposition–fluorescence in situ hybridization (CARD–FISH) with Endozoicomonas-specific probes confirmed their residence as large aggregations deep within coral tissues. Using fine-scale genotyping techniques and single-cell genomics, we demonstrate that P. verrucosa harbors the same Endozoicomonas, whereas S. pistillata associates with geographically distinct genotypes. This specificity may be shaped by the different reproductive strategies of the hosts, potentially uncovering a pattern of symbiont selection that is linked to life history. Spawning corals such as P. verrucosa acquire prokaryotes from the environment. In contrast, brooding corals such as S. pistillata release symbiont-packed planula larvae, which may explain a strong regional signature in their microbiome. Our work contributes to the factors underlying microbiome specificity and adds detail to coral holobiont functioning.This research was supported by a KAUST-WHOI Post-doctoral Partnership Award to MN and a KAUST-WHOI Special Academic Partnership Funding Reserve Award to CRV and AA. Research in this study was further supported by baseline research funds to CRV by KAUST and NSF award OCE-1233612 to AA. RR was supported by the ct-PIRE Project, Robert Lemelson Fellowship, Graduate Research Award (UCLA), Women Divers Hall of Fame—Sister Fund Conservation Award and a Betty and E. P. Franklin Grant in Tropical Biology and Conservation

    Analytical solution of generalized Burton--Cabrera--Frank equations for growth and post--growth equilibration on vicinal surfaces

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    We investigate growth on vicinal surfaces by molecular beam epitaxy making use of a generalized Burton--Cabrera--Frank model. Our primary aim is to propose and implement a novel analytical program based on a perturbative solution of the non--linear equations describing the coupled adatom and dimer kinetics. These equations are considered as originating from a fully microscopic description that allows the step boundary conditions to be directly formulated in terms of the sticking coefficients at each step. As an example, we study the importance of diffusion barriers for adatoms hopping down descending steps (Schwoebel effect) during growth and post-growth equilibration of the surface.Comment: 16 pages, REVTeX 3.0, IC-DDV-94-00

    Case report: Morphological changes evident after manual therapy in two cases of late-diagnosed developmental dysplasia of the hip

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    BackgroundLate diagnosed Developmental Dysplasia of the Hip (DDH) is the detection of DDH after 3 months of age and is associated with significantly poorer outcomes than when diagnosed and managed early. Late diagnosed DDH has lower rates of success with bracing, higher rates of surgery and higher rates of complications, including avascular necrosis of the femoral head and early osteoarthritis of the hip. We describe two cases of late-diagnosed DDH which demonstrated changes in femoroacetabular joint morphology on radiographic interpretation after a 6-month trial period of manual therapy.Case PresentationTwo cases (13 and 30 months of age) with late-diagnosed DDH presented to a private chiropractic clinic for conservative, non-bracing management. One case had unilateral DDH and the other bilateral DDH. A trial of manual therapy was utilized over a 6-month period. Both cases demonstrated changes to femoroacetabular morphology as well as improvements in gross motor activity and lower extremity muscle tone.ConclusionManual therapy, as an adjunct or alternative to static bracing, may be of benefit in individuals with late-diagnosed DDH not responding to bracing, and prior to more invasive interventions. Additional cases of manual therapy-based management of this condition are required to inform the design of future trials to investigate this hypothesis

    The Journal of the Friends' Historical Society vol. 4 No. 3

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    1. Notices. 2. Notes and Queries. 3. Visits of American Ministers to Europe. 4. A Prophecy of Toleration. 5. Presentations of Quakers in Episcopal Visitations, 1662-1679. 6. Editors' Notes. 7. Episodes in the Life of May Drummond II. 8. Review of Hancock's "Peculium". 9. The Wilkinson and Story Controversy in Bristol. 10. Service in Sackcloth. 11. Present State of the Nonconformists. 12. A Vision seen by George Fox. 13. Friends in Current Literature. 14. George Fox and the Durham College

    Reduction of carboplatin induced emesis by ondansetron.

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    Ondansetron is a selective 5-HT3 antagonist with significant antiemetic properties in patients receiving cytotoxic chemotherapy. Patients who had suffered severe vomiting on carboplatin alone (23 patients with ovarian carcinoma) or in combination (two patients with testicular cancer) despite intensive antiemetic regimens were treated with ondansetron, given as 8 mg immediately prior to carboplatin followed by 8 mg orally, 8 hourly for 5 days. Twenty-five patients received 58 courses of ondansetron. In the first 24 h after the first course of chemotherapy with ondansetron, 17 patients (68%) experienced no vomiting, five patients (20%) had almost complete control and the other three patients had partial control. During the subsequent 4 days slightly lesser control was achieved. Nausea was similarly controlled in most patients. Twenty-two patients stated a preference for ondansetron with future chemotherapy. Fourteen patients received additional chemotherapy with ondansetron and in only three patients did the efficacy of therapy lessen. Toxicity was mild and transient with headache and constipation predominant. No extrapyramidal reaction was seen. Sedation was absent. Ondansetron is highly effective in refractory vomiting associated with carboplatin chemotherapy. It may be particularly beneficial when an extrapyramidal reaction has occurred on previous antiemetics and when sedation is unacceptable
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