188,104 research outputs found
Towards the tumble resistant microlight
No full textThe tumble mode is a pitching departure from controlled flight which leads to a pitch autorotation that is generally unrecoverable – resulting in vertical ground impact, usually preceded by in-flight breakup (the mechanism for which, surprisingly, can sometimes prevent loss of life). This was identified in work led by the British Microlight Aircraft Association beginning in 1997 as a response to a number of fatal accidents in Rogallo winged microlight aeroplanes, although the tumble is also known to occur to hang-gliders. This paper explains how this class of aeroplane is controlled, and how it has been found that they can enter the tumble mode. The mechanism by which the tumble can be entered is described. This has led to work showing how flight testing can be used to establish and demonstrate resistance to tumble entry – particularly important with increasing number of very high performance flexwings. These flight tests will be explained, together with the significance of the results. Recent accident investigation work has also shown a new mechanism of tumble entry, through partial failure of the A-frame structure and the pitch-trimmer mechanism. Also described is a possible relevance to well known historical accidents to flying wing aeroplanes– specifically the YB-49 and dH-108, and discovered data on the characteristics of the BKB-1flying wing glider; are also described
Use of airborne vehicles as research platforms
Full text linkThis is the accepted version of the following chapter: Gratton, G. 2012. Use of Airborne Vehicles as Research Platforms. Encyclopedia of Aerospace Engineering, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/9780470686652.eae604/full. Copyright @ John Wiley & Sons 2012.The use of aircraft is often valuable to position airborne sensors or to conduct experiments in ways not possible purely on the ground. An airframe, typically an older one, must be selected then adapted to the role – likely to include inlets, windows, structural changes, power supply, computing and data recording capacity, and likely the provision of external hardpoints. Once the research vehicle is created, the instruments on board will require calibration, either in isolation or by intercomparison against already calibrated instruments on board another aircraft. This calibration process will continue throughout the life of the airplane. Additionally, an operating organization must be created and obtain any necessary organizational approvals. For some specialist applications, unmanned aerial vehicles (UAVs) may also be used, which carry some special considerations of autonomy and interoperability, but similar concerns of instrument, vehicle, and operational integrity
Isolation of novel microsatellite markers for the clouded Apollo (P-mnemosyne Linnaeus, 1758; Lepidoptera, Papilionidae)
No full textFive novel polymorphic microsatellite loci were isolated and characterized using an enriched genomic DNA library for Parnassius mnemosyne, a European butterfly of conservation concern, and a valuable model for the study of metapopulation dynamics. Allele numbers ranged from 4 to 12 and observed and expected heterozygosities from 0.17 to 0.74 and from 0.26 to 0.835, respectively. Two samples from geographically close populations were analyzed, demonstrating that the new markers can be successfully employed to investigate fine-scale population structure
Phylogeography and conservation genetics of Parnassius mnemosyne L.: 1758 (Lepidoptera, Papilionidae)
No full textIl presente lavoro ha l’obiettivo di fornire una base di informazioni sulle relazioni tra la distribuzione spaziale e la variazione genetica in popolazioni del lepidottero Parnassius mnemosyne.
Un totale di 172 individui provenienti da 58 località, rappresentative dell’intero areale della specie, sono stati caratterizzati per le sequenze di due geni mitocondriali (COI e ND5) e un gene nucleare (EF-1α). Un campione di 397 individui da 16 località italiane (Alpi centro-orientali, Appennino Centrale e Sicilia) è stato analizzato impiegando 5 loci microsatellite appositamente sviluppati.
I risultati hanno messo in luce evidenze genetiche della lunga e complessa storia geografica di questa specie e l’analisi della distribuzione geografica degli aplotipi mitocondriali ha permesso di ricostruirne con una certa accuratezza le tappe più significative. È chiaro che P. mnemosyne aveva raggiunto una distribuzione Eurasiatica simile all’attuale già alla fine del Pleistocene inferiore. La presenza di aplogruppi fortemente differenziati in aree geografiche distinte indica chiaramente che periodi di grande frammentazione dell’areale hanno contraddistinto il Pleistocene medio e superiore. In particolare, le popolazioni dell’Europa sud-occidentale (Pirenei, penisola Italiana, Sicilia, Alpi Occidentali) e quelle dell’Europa nord-orientale (dalle Alpi Orientali, e la Penisola Balcanica fino agli Urali) appaiono caratterizzate da aplotipi mitocondriali altamente divergenti (l’inizio della divergenza è databile a oltre 1 milione di anni fa) e da sequenze nucleari distinte. I due gruppi meritano senz’altro di essere considerati come differenti Unità Evolutivamente Significative (ESUs) e rappresentano probabilmente specie distinte sensu Mayr. Popolazioni portatrici dei due diversi aplogruppi sono state osservate a poche decine di chilometri di distanza nelle Alpi centro-orientali italiane e non mostrano traccia di introgressione mitocondriale e nucleare. L’impiego del DNA microsatellite ha confermato il completo differenziamento tra i profili genetici di individui portatori dei differenti aplotipi mitocondriali.
I marcatori microsatellite hanno permesso di individuare l’esistenza di una debole struttura genetica su scala locale nelle popolazioni del Parco Regionale dei Monti Simbruini (Lazio) e hanno evidenziato una significativa riduzione della variabilità genetica nelle popolazioni marginali dei Monti Aurunci (Lazio) e soprattutto della Sicilia.
I risultati ottenuti intendono costituire una base di conoscenze genetiche utile alla pianificazione di future misure volte alla conservazione della specie.Present work is addressed at providing basic information about relationships between patterns of geographic distribution and genetic variation in populations of the montane butterfly Parnassius mnemosyne.
A total of 172 individuals from 58 localities representing most of the species range have been sequenced at part of two mitochondrial genes (COI and ND5) and one nuclear gene (EF-1α). A sample of 397 individuals from 16 italian localities (Central-Eastern Alps, Central Apennine and Sicily) has been characterized at 5 newly developed microsatellite loci.
Phylogeographic analysis of mitochondrial and nuclear sequences showed that P. mnemosyne populations bear genetic traces of a geographic history about one million years long. Highly divergent mitochondrial lineages mark at least two evolutionarily significant units in Europe, which may indeed represent different species. Nested Clade Analysis was employed in a reconstruction of the main stages of the history of the species during the Pleistocene, including possible evidences of survival in Northern refugia during last glacial episodes. Novel microsatellite markers have been tested on some critical areas and provided evidences of genetic structuring at the scale of a few kilometers. Marked reduction of genetic variability was evidenced in “marginal” populations from Monti Aurunci (Lazio) and Sicily. Results are meant to offer a genetically based framework for planning future conservation effort
Accounting for pseudoreplication is not possible when the source of nonindependence is unknown
No full textRepeated observations of the same individuals or other units, which can lead to clustered observations, are common in animal behaviour research, and mixed models are commonly employed to model and account for such clustering in the data and avoid pseudoreplication. However, in some cases, while the data might comprise repeated samples from the same individuals, the precise identity of the individuals from which samples originated is unknown. In a recent paper Garamszegi (2016, Animal Behaviour, 120, 223–234) suggested an approach to account for pseudoreplication which is based on repeatedly assigning random subject identities to the samples and then analysing the data using a mixed model or averaged values for each randomly assigned identity. Here we tested this approach using a simulation study. We found that the approach suggested by Garamszegi leads to clearly inflated type I error rates that were essentially the same as those obtained from a naïve linear model simply ignoring individual identity and that only a model based on the correct subject identities roughly produced the nominal type I error rate. We conclude that, currently, there is no method available that allows pseudoreplication to be controlled when subject identities are unknown
Pleistocene evolutionary history of the Clouded Apollo (Parnassius mnemosyne): genetic signatures of climate cycles and a 'time-dependent' mitochondrial substitution rate
Full text linkGenetic data are currently providing a large amount of new information on past distribution of species and are contributing to a new vision of Pleistocene ice ages. Nonetheless, an increasing number of studies on the 'time dependency' of mutation rates suggest that date assessments for evolutionary events of the Pleistocene might be overestimated. We analysed mitochondrial (mt) DNA (COI) sequence variation in 225 Parnassius mnemosyne individuals sampled across central and eastern Europe in order to assess (i) the existence of genetic signatures of Pleistocene climate shifts; and (ii) the timescale of demographic and evolutionary events. Our analyses reveal a phylogeographical pattern markedly influenced by the Pleistocene/Holocene climate shifts. Eastern Alpine and Balkan populations display comparatively high mtDNA diversity, suggesting multiple glacial refugia. On the other hand, three widely distributed and spatially segregated lineages occupy most of northern and eastern Europe, indicating postglacial recolonization from different refugial areas. We show that a conventional 'phylogenetic' substitution rate cannot account for the present distribution of genetic variation in this species, and we combine phylogeographical pattern and palaeoecological information in order to determine a suitable intraspecific rate through a Bayesian coalescent approach. We argue that our calibrated 'time-dependent' rate (0.096 substitutions/million years), offers the most convincing time frame for the evolutionary events inferred from sequence data. When scaled by the new rate, estimates of divergence between Balkan and Alpine lineages point to c. 19 000 years before present (last glacial maximum), and parameters of demographic expansion for northern lineages are consistent with postglacial warming (5-11 000 years before present)
Composing the evolutionary puzzle of the last remains of trout (Salmo trutta complex) diversity in Italy.
No full textMediterranean trout populations display a diversity of forms, representing a valuable model for the study of adaptation and a puzzling dilemma for taxonomists and biogeographers, rendered even more problematic by the widespread introgression of allochthonous (Atlantic) genes. Current Bayesian methods allow complex evolutionary models to be tested, offering the opportunity to statistically evaluate hypotheses about the evolutionary relationships of Mediterranean trout populations.
We used Approximate Bayesian Computation to test competing evolutionary scenarios for the main trout lineages (‘marble’ and Mediterranean ‘brown’ trout) autochtonous to the Italian basins, including the roles of geographical barriers and climate change in shaping the historical distribution of distinct lineages, and accounting for allochthonous introgression.
Our main results were that: i) the gene pool of the Adriatic endemic ‘marble’ trout started diverging earlier than the separation of Atlantic and Mediterranean lineages of ‘brown’ trout; ii) a relatively complex model of divergence, involving gene flow from Mediterranean ‘brown’ trout into the ancestral gene pool of marble trout is most consistent with the genetic data; iii) autochthonous gene pools of ‘brown’ trout in the Tyrrhenian and Adriatic basins of the Italian peninsula most likely diverged around the Last Glacial Maximum, indicating that movement along the coasts of southern Italy was possible as a result of climate/salinity conditions.
Our approach has, for the first time, allowed us to suggest an explicit model for the evolution of the main autochthonous trout lineages in Italy. We are currently using the same approach to test the hypothesis of speciation by hybridization in the Lake Garda endemic Salmo carpio
The evolutionary jigsaw puzzle of the surviving trout (Salmo trutta L. complex) diversity in the Italian region. A multilocus Bayesian approach.
No full textMediterranean trout populations display a diversity of phenotypes, representing a valuable model for the
study of adaptation and a puzzling dilemma for taxonomists and biogeographers, which is further entangled
by the widespread introgression of allochthonous genes.
In this paper we analysed DNA polymorphism at multiple loci (sequence variation of the mitochondrial
control region and eight nuclear fragments and length variation at eleven nuclear microsatellite loci) in
representative samples of the autochthonous taxonomic diversity described in Italian trout populations
(Salmo marmoratus, S. carpio, S. cenerinus, S. cettii and S. fibreni) and in samples from hatchery-originated
strains of Atlantic S. trutta. We employed model-based clustering and Approximate Bayesian Computation
in order to: (i) describe the phylogeographic structure of Italian autochthonous trout populations;
(ii) evaluate a set of evolutionary/biogeographic models. The inclusion of hatchery-originated strains
allowed to account for man-mediated allochthonous introgression in Italian populations.
Our results (i) showed that the analysed sample consists of two main autochthonous evolutionary lineages,
including the marble trout populations on one side (‘marble’ lineage) and the three peninsular
populations of S. cettii, S. cenerinus and S. fibreni on the other side (‘peninsular’ lineage); (ii) indicated that
S. carpio originated from a ‘peninsular’ population, with a possible, limited contribution from the ‘marble’
lineage; (iii) pointed out that the ‘marble’ lineage started diverging before the separation of the ‘peninsular’
lineage from Atlantic S. trutta; (iv) suggested that a model of divergence involving gene flow from
the ‘peninsular’ population into the ancestral gene pool of ‘marble’ trout is most consistent with the
genetic data; (v) provided evidence that the autochthonous trout gene pools in the Tyrrhenian and Adriatic
basins of the Italian peninsula started diverging very recently (most likely after the last glacial
maximum)
Combined kinetic and spectroscopic study of oxidation of azo dyes in surfactant solutions by hypochlorite
No full textCombined kinetic, spectroscopic and thermodynamic investigations have been carried out to examine the influence of cationic, anionic and nonionic surfactants upon the oxidation of an azo dye, II, by hypochlorite. Oxidation rates were unaffected by the presence of anionic or nonionic surfactant (SDS or C12E5) either in micellar or submicellar regions: indicating the absence of any specific dye-surfactant interactions. On the other hand, specific interactions were observed with cationic surfactants, both in submicellar and micellar regions. Addition of CTAts to dye II produced a reduction in intensity of its UV-vis spectrum and caused oxidation rates to decrease. These are attributed to formation of a sparingly soluble 1:1 complex with the dye, via interactions with the sulfonate groups. Binding of DTAC to the dye in sub-micellar regions results in a slight enhancement in oxidation rates, which is attributed to break-up of small, soluble dye aggregates. In micellar regions, there was evidence that the dye becomes incorporated into the surface of micelles formed by both cationic surfactants, where they become inert to reaction with hypochlorite
To all persecutors, both by words and actions. [electronic resource] : A few words for the clearing of my self and the truth I profess in real love; from him that seeks the good of all mankind in general, having real love to all, especially the houshould of faith, who are redeemed to God, out of the uncleanness of the world, who are in scorn called Quakers.
No full textCaption title."Written ... in the year 1682 ... John Gratton"--P. 32.Books printed and sold by Andrew Sowle: p. [1]Imperfect: torn with slight loss of print.Reproduction of original in the Swarthmore College Library.Wing (2nd ed.),Electronic reproduction
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