379 research outputs found

    Empirical Estimate of Lyman-alpha Escape Fraction in a Statistical Sample of Lyman-alpha Emitters

    Full text link
    The Lyman-alpha (Lya) recombination line is a fundamental tool for galaxy evolution studies and modern observational cosmology. However, subsequent interpretations are still prone to a number of uncertainties. Besides numerical efforts, empirical data are urgently needed for a better understanding of Lya escape process. We empirically estimate the Lyman-alpha escape fraction fesc(Lya) in a statistically significant sample of z ~ 0 - 0.3 galaxies in order to calibrate high-redshift Lyman-alpha observations. An optical spectroscopic follow-up of a sub-sample of 24 Lyman-alpha emitters (LAEs) detected by GALEX at z ~ 0.2-0.3, combined with a UV-optical sample of local starbursts, both with matched apertures, allow us to quantify the dust extinction through Balmer lines, and to estimate the Lyman-alpha escape fraction from the Halpha flux corrected for extinction in the framework of the recombination theory. The global escape fraction of Lyman-alpha radiation spans nearly the entire range of values, from 0.5 to 100 %, and fesc(Lya) clearly decreases with increasing nebular dust extinction E(B-V). Several objects show fesc(Lya) greater than fesc(continuum) which may be an observational evidence for clumpy ISM geometry or for an aspherical ISM. Selection biases and aperture size effects may still prevail between z ~ 0.2-0.3 LAEs and local starbursts, which may explain the difference observed for fesc(Lya).Comment: 4 pages, 2 figures, accepted for publication in Astronomy and Astrophysic

    Security Analysis of CPace

    Get PDF
    In response to standardization requests regarding password-authenticated key exchange (PAKE) protocols, the IRTF working group CFRG has setup a PAKE selection process in 2019, which led to the selection of the CPace protocol in the balanced setting, in which parties share a common password. In subsequent standardization efforts, the CPace protocol further developed, yielding a protocol family whose actual security guarantees in practical settings are not well understood. In this paper, we provide a comprehensive security analysis of CPace in the universal composability framework. Our analysis is realistic in the sense that it captures adaptive corruptions and refrains from modeling CPace's Map2Pt function that maps field elements to curve points as an idealized function. In order to extend our proofs to different CPace variants optimized for specific elliptic-curve ecosystems, we employ a new approach which represents the assumptions required by the proof as libraries accessed by a simulator. By allowing for the modular replacement of assumptions used in the proof, this new approach avoids a repeated analysis of unchanged protocol parts and lets us efficiently analyze the security guarantees of all the different CPace variants. As a result of our analysis, all of the investigated practical CPace variants enjoy adaptive UC security

    Recommendations for the Selection of Methods for the Analysis of eCollaboration based on a Systematic Literature Review

    Get PDF
    Learning Analytics plays an increasing role in the analysis of virtual learning activities. This article addresses the gap between educational needs and technical supply. By means of a Systematic Literature Review of the LAK conferences the authors extracted observations, methods and tools which represent potential solutions for a given eCollaboration scenario. Based on three prioritised examples of an observation sheet, methods are derived and recommendations for the use of Learning Analytics tools are given. The result is a catalogue that enable users to select suitable methods and tools for an implementation. The (semi-) automation can increase the efficiency of Community Managers in monitoring the participants and hence make real-time intervention feasible

    Synchrotron-based nu-XRF mapping and mu-FTIR microscopy enable to look into the fate and effects of tattoo pigments in human skin

    Get PDF
    The increasing prevalence of tattoos provoked safety concerns with respect to particle distribution and effects inside the human body. We used skin and lymphatic tissues from human corpses to address local biokinetics by means of synchrotron X-ray fluorescence (XRF) techniques at both the micro (mu) and nano (nu) scale. Additional advanced mass spectrometry-based methodology enabled to demonstrate simultaneous transport of organic pigments, heavy metals and titanium dioxide from skin to regional lymph nodes. Among these compounds, organic pigments displayed the broadest size range with smallest species preferentially reaching the lymph nodes. Using synchrotron mu-FTIR analysis we were also able to detect ultrastructural changes of the tissue adjacent to tattoo particles through altered amide I alpha-helix to beta-sheet protein ratios and elevated lipid contents. Altogether we report strong evidence for both migration and long-term deposition of toxic elements and tattoo pigments as well as for conformational alterations of biomolecules that likely contribute to cutaneous inflammation and other adversities upon tattooing

    Doenças primĂĄrias da pele e manifestaçÔes cutĂąneas de doenças sistĂȘmicas em suĂ­nos

    Get PDF
    Skin diseases in pigs can negatively impact the production. They cause losses related to the death of the affected pigs, to the cost with the treatment, growth retardation and condemnations in the slaughterhouses. This study was developed to determine the frequency and describe the histopathological findings of skin diseases in pigs in different age groups through a retrospective study from 2006 to 2018. A total of 154 conclusive cases were analyzed, including skin restricted diseases (allergic dermatitis, exudative epidermitis, vesicular dermatitis, pityriasis rosea, swinepox, follicular cyst, papilloma and scrotal hemangioma) or skin lesions secondary to systemic diseases (erysipelas, porcine dermatitis and nephropathy syndrome [PDNS], bacterial septicemia and multiple hemorrhages without definite cause). The skin lesions were classified as bacterial (46.1%), viral (26.6%), allergic (12.3%), neoplastic (1.3%) and others (13.6%). Swine erysipelas was the most frequent diagnosis (47/154), followed by PDNS (23/154), allergic dermatitis (19/154) and exudative epidermitis (15/154). Vesicular dermatitis (9/154), pityriasis rosea (9/154), septicemia with cutaneous manifestations (9/154), swinepox (9/154) and multiple hemorrhages without definite cause (7/154) were also observed. Follicular cyst (3/154), hyperkeratosis without definite cause (2/154), papilloma (1/154), and scrotal hemangioma (1/154) were less frequently described. Of the conclusive diagnosis, age was reported in 138 cases, with the highest frequency of skin lesions observed at the inspection process during slaughter (56/138).As doenças de pele em suĂ­nos podem impactar negativamente a produção. Estas causam perdas relacionadas Ă  morte dos acometidos, a custo com tratamentos, atraso no crescimento e condenaçÔes nos frigorĂ­ficos. Este trabalho foi desenvolvido para determinar a frequĂȘncia e descrever os achados histopatolĂłgicos das doenças de pele em suĂ­nos nas diferentes faixas etĂĄrias, atravĂ©s de um estudo retrospectivo no perĂ­odo de 2006 a 2018. Foram analisados 154 casos conclusivos, incluindo as doenças restritas a pele (dermatites alĂ©rgicas, epidermite exsudativa, dermatite vesicular, pitirĂ­ase rĂłsea, varĂ­ola suĂ­na, cisto folicular, papiloma e hemangioma escrotal) e as secundĂĄrias a doenças sistĂȘmicas (erisipela, sĂ­ndrome dermatite nefropatia suĂ­na [SDNS], septicemia bacteriana e hemorragias mĂșltiplas de causa nĂŁo determinada). Estas foram classificadas em bacterianas (46,1%), virais (26,6%), alĂ©rgicas (12,3%), neoplĂĄsicas (1,3%) e outras (13,6%). A erisipela suĂ­na foi a enfermidade mais diagnosticada (47/154), seguida por SDNS (23/154), dermatite alĂ©rgica (19/154) e epidermite exsudativa (15/154). Observamos ainda dermatite vesicular (9/154), pitirĂ­ase rĂłsea (9/154), septicemia bacteriana com manifestaçÔes cutĂąneas (9/154), varĂ­ola suĂ­na (9/154) e hemorragias mĂșltiplas de causa nĂŁo determinada (7/154). Em menor nĂșmero, cisto folicular (3/154), hiperqueratose sem causa definida (2/154), papiloma (1/154) e hemangioma escrotal (1/154). Dos casos conclusivos, a idade foi informada em 138 casos, sendo a maior frequĂȘncia das lesĂ”es de pele observadas na linha de inspeção, durante o abate (56/138)

    Symbolic character productions in the mousterian site of La Roche-Cotard in Langeais (Indre-et-Loire, France) and their geological context

    Get PDF
    Le site de La Roche-Cotard se trouve sur la rive droite de la vallĂ©e de la Loire Ă  une vingtaine de kilomĂštres en aval de Tours. Le gisement, mis au jour en 1846, suite Ă  l’extraction de matĂ©riaux, a Ă©tĂ© fouillĂ© en 1912. Les recherches ont repris de 1975 Ă  1978, puis Ă  partir de 2008.Les premiĂšres recherches, en 1975, permettent la dĂ©couverte, devant l’entrĂ©e de la grotte, d’un lambeau de plage de Loire sur lequel les hommes de NĂ©andertal ont allumĂ© un feu, abandonnĂ© des piĂšces d’industrie lithique et une protofigurine, appelĂ©e par M. Lorblanchet « masque de La Roche-Cotard » (Marquet, Lorblanchet 2000, 2003). Un abri trĂšs bas est Ă©galement dĂ©couvert ; il contient un peu d’industrie lithique et un amĂ©nagement de blocs au sol.À partir de 2008, les nouvelles fouilles mettent au jour une petite grotte-abri comblĂ©e de sĂ©diments, prĂ©sentant Ă©galement des indices d’occupation par l’homme de NĂ©andertal. Elles poursuivent Ă©galement le travail Ă  l’intĂ©rieur de la cavitĂ© principale.L’examen approfondi des parois, effectuĂ© par J.-C. Marquet avec les appuis de M. Lorblanchet, P. Paillet et E. Man-Estier, permet de reconnaĂźtre quatre panneaux, trois de tracĂ©s digitaux et un de ponctuations. Ces traces sont visibles car il y a eu enlĂšvement de matiĂšre (au doigt ou Ă  l’aide d’un instrument pouvant donner le mĂȘme type de trace) sur la paroi de « craie tuffeau » (nom vernaculaire donnĂ© Ă  cette roche) altĂ©rĂ©e, recouverte par un mince film de limon argileux. Sur l’un des panneaux, on observe une figuration circulaire, sur les deux autres des ensembles de tracĂ©s parallĂšles, organisĂ©s et rythmĂ©s. Quatre taches ocre rouge ont Ă©tĂ© repĂ©rĂ©es.Les Ă©tudes gĂ©omĂ©trique, granulomĂ©trique et morphologique des dĂ©pĂŽts, ainsi que les datations des os par le 14C et des sĂ©diments par la mĂ©thode OSL, montrent qu’aprĂšs l’occupation par les hommes de NĂ©andertal, l’entrĂ©e de la cavitĂ© a Ă©tĂ© occultĂ©e, pour n’ĂȘtre rĂ©ouverte qu’en 1846 (voire seulement en 1912).Aucune datation directe des tracĂ©s n’est possible. Cependant, leur altĂ©ration locale, les datations des os et des sĂ©diments situĂ©s juste devant les panneaux et naturellement celle de la fermeture de l’entrĂ©e de la grotte aprĂšs l’occupation par NĂ©andertal autorisent Ă  exclure un Ăąge rĂ©cent.Masque, tracĂ©s et traces de peinture dans une cavitĂ© inaccessible Ă  Homo sapiens jusqu’en 1846, gĂ©omĂ©trie des dĂ©pĂŽts, confĂšrent au site de La Roche-Cotard un trĂšs grand intĂ©rĂȘt au moment oĂč est sĂ©rieusement reconsidĂ©rĂ©e la question des compĂ©tences de l’homme de NĂ©andertal.La Roche-Cotard site is located on the right side of the Loire valley, about 20 km down-river from Tours. The site, uncovered in 1846, following the extraction of materials, was excavated in 1912. Research was taken up again from 1975 to 1978, then from 2008 onwards.The first reprise of excavations in 1975 allowed for the discovery, at the entrance of a cave on a beach of the Loire on which Neanderthals have made fire, of stone tools and a proto-figurine that was named by M. Lorblanchet the “Mask of La Roche-Cotard” (Marquet & Lorblanchet, 2000, 2003). A very low shelter was also discovered, which contains some stone tools and a layout of blocks on the ground.The second reprise of excavations in 2008 allowed for the discovery of a small cave-shelter filled with sediments, presenting also indications of occupation by Neanderthals; but above all it enabled further work on the inside of the main cavity.Deeper examination of the cave walls, carried out by J.-C. Marquet, with the support of M. Lorblanchet, P. Paillet and E. Man-Estier, allowed for the recognition of three panels of finger flutings and a panel of point-marks. These marks are visible due to the removal of matter (by hand or with the aid of an instrument giving the same type of marks) on the weathered « tuffeau chalk » wall, recovered by a thin film of silty clay. On one of the panels can be observed a circular representation, on the other two, sets of parallel markings, organized and rhythmic. Four red ochre stains were also discovered.Geometric, granulometric and morphologic studies of the deposits, as well as 14C datings of bones and datings of sediments through the OSL method, show that following the occupation by Neanderthals, the entrance to the cave was blotted out and was only reopened in 1846, or even in 1912.No direct dating of the markings is possible. However, their localized weathering, datings of bones and sediments found just in front of the panels and naturally the closure of the cave’s entrance after the occupation by Neanderthals allows us to rule out the possibility of a recent age.Mask, markings and traces of painting in a cavity inaccessible to Homo sapiens until 1846, geometry of deposits, all add to the great interest in La Roche-Cotard site, at the very moment when we reconsider seriously the question of the competences of the Neanderthals

    Les productions à caractÚre symbolique du site moustérien de La Roche-Cotard à Langeais (Indre-et-Loire, France) dans leur contexte géologique

    Get PDF
    Le site de La Roche-Cotard se trouve sur la rive droite de la vallĂ©e de la Loire Ă  une vingtaine de kilomĂštres en aval de Tours. Le gisement, mis au jour en 1846, suite Ă  l’extraction de matĂ©riaux, a Ă©tĂ© fouillĂ© en 1912. Les recherches ont repris de 1975 Ă  1978, puis Ă  partir de 2008.Les premiĂšres recherches, en 1975, permettent la dĂ©couverte, devant l’entrĂ©e de la grotte, d’un lambeau de plage de Loire sur lequel les hommes de NĂ©andertal ont allumĂ© un feu, abandonnĂ© des piĂšces d’industrie lithique et une protofigurine, appelĂ©e par M. Lorblanchet « masque de La Roche-Cotard » (Marquet, Lorblanchet 2000, 2003). Un abri trĂšs bas est Ă©galement dĂ©couvert ; il contient un peu d’industrie lithique et un amĂ©nagement de blocs au sol.À partir de 2008, les nouvelles fouilles mettent au jour une petite grotte-abri comblĂ©e de sĂ©diments, prĂ©sentant Ă©galement des indices d’occupation par l’homme de NĂ©andertal. Elles poursuivent Ă©galement le travail Ă  l’intĂ©rieur de la cavitĂ© principale.L’examen approfondi des parois, effectuĂ© par J.-C. Marquet avec les appuis de M. Lorblanchet, P. Paillet et E. Man-Estier, permet de reconnaĂźtre quatre panneaux, trois de tracĂ©s digitaux et un de ponctuations. Ces traces sont visibles car il y a eu enlĂšvement de matiĂšre (au doigt ou Ă  l’aide d’un instrument pouvant donner le mĂȘme type de trace) sur la paroi de « craie tuffeau » (nom vernaculaire donnĂ© Ă  cette roche) altĂ©rĂ©e, recouverte par un mince film de limon argileux. Sur l’un des panneaux, on observe une figuration circulaire, sur les deux autres des ensembles de tracĂ©s parallĂšles, organisĂ©s et rythmĂ©s. Quatre taches ocre rouge ont Ă©tĂ© repĂ©rĂ©es.Les Ă©tudes gĂ©omĂ©trique, granulomĂ©trique et morphologique des dĂ©pĂŽts, ainsi que les datations des os par le 14C et des sĂ©diments par la mĂ©thode OSL, montrent qu’aprĂšs l’occupation par les hommes de NĂ©andertal, l’entrĂ©e de la cavitĂ© a Ă©tĂ© occultĂ©e, pour n’ĂȘtre rĂ©ouverte qu’en 1846 (voire seulement en 1912).Aucune datation directe des tracĂ©s n’est possible. Cependant, leur altĂ©ration locale, les datations des os et des sĂ©diments situĂ©s juste devant les panneaux et naturellement celle de la fermeture de l’entrĂ©e de la grotte aprĂšs l’occupation par NĂ©andertal autorisent Ă  exclure un Ăąge rĂ©cent.Masque, tracĂ©s et traces de peinture dans une cavitĂ© inaccessible Ă  Homo sapiens jusqu’en 1846, gĂ©omĂ©trie des dĂ©pĂŽts, confĂšrent au site de La Roche-Cotard un trĂšs grand intĂ©rĂȘt au moment oĂč est sĂ©rieusement reconsidĂ©rĂ©e la question des compĂ©tences de l’homme de NĂ©andertal.La Roche-Cotard site is located on the right side of the Loire valley, about 20 km down-river from Tours. The site, uncovered in 1846, following the extraction of materials, was excavated in 1912. Research was taken up again from 1975 to 1978, then from 2008 onwards.The first reprise of excavations in 1975 allowed for the discovery, at the entrance of a cave on a beach of the Loire on which Neanderthals have made fire, of stone tools and a proto-figurine that was named by M. Lorblanchet the “Mask of La Roche-Cotard” (Marquet & Lorblanchet, 2000, 2003). A very low shelter was also discovered, which contains some stone tools and a layout of blocks on the ground.The second reprise of excavations in 2008 allowed for the discovery of a small cave-shelter filled with sediments, presenting also indications of occupation by Neanderthals; but above all it enabled further work on the inside of the main cavity.Deeper examination of the cave walls, carried out by J.-C. Marquet, with the support of M. Lorblanchet, P. Paillet and E. Man-Estier, allowed for the recognition of three panels of finger flutings and a panel of point-marks. These marks are visible due to the removal of matter (by hand or with the aid of an instrument giving the same type of marks) on the weathered « tuffeau chalk » wall, recovered by a thin film of silty clay. On one of the panels can be observed a circular representation, on the other two, sets of parallel markings, organized and rhythmic. Four red ochre stains were also discovered.Geometric, granulometric and morphologic studies of the deposits, as well as 14C datings of bones and datings of sediments through the OSL method, show that following the occupation by Neanderthals, the entrance to the cave was blotted out and was only reopened in 1846, or even in 1912.No direct dating of the markings is possible. However, their localized weathering, datings of bones and sediments found just in front of the panels and naturally the closure of the cave’s entrance after the occupation by Neanderthals allows us to rule out the possibility of a recent age.Mask, markings and traces of painting in a cavity inaccessible to Homo sapiens until 1846, geometry of deposits, all add to the great interest in La Roche-Cotard site, at the very moment when we reconsider seriously the question of the competences of the Neanderthals
    • 

    corecore