1,869 research outputs found
A new species of the basal araneomorph spider genus Ectatosticta (Araneae, Hypochilidae) from China
The hypochilid spider Ectatosticta davidi (Simon) is redescribed on the basis of adults from Mt. Taibaishan in Shaanxi Province, China; the specimens from Qinghai Province previously identified as E. davidi by most modern authors belong to a new species described as E. deltshevi. Keywords: Araneae, Araneomorphae, Hypochilidae, Ectatosticta, Chin
Formation of PAHs and Carbonaceous Solids in Gas-Phase Condensation Experiments
Carbonaceous grains represent a major component of cosmic dust. In order to
understand their formation pathways, they have been prepared in the laboratory
by gas-phase condensation reactions such as laser pyrolysis and laser ablation.
Our studies demonstrate that the temperature in the condensation zone
determines the formation pathway of carbonaceous particles. At temperatures
lower than 1700 K, the condensation by-products are mainly polycyclic aromatic
hydrocarbons (PAHs), that are also the precursors or building blocks for the
condensing soot grains. The low-temperature condensates contain PAH mixtures
that are mainly composed of volatile 3-5 ring systems. At condensation
temperatures higher than 3500 K, fullerene-like carbon grains and fullerene
compounds are formed. Fullerene fragments or complete fullerenes equip the
nucleating particles. Fullerenes can be identified as soluble components.
Consequently, condensation products in cool and hot astrophysical environments
such as cool and hot AGB stars or Wolf Rayet stars should be different and
should have distinct spectral properties.Comment: 7 pages, 5 figure
First Asian spiders of the family Caponiidae (Araneae, Haplogynae).
12 p. : ill. ; 26 cm.
Includes bibliographical references (p. 11-12).A new genus and species, Laoponia saetosa, are established to contain the first members of the family Caponiidae to be discovered in Asia. Only two Old World genera of caponiids have been described, both from Africa; in having only two eyes, the newly collected spiders from Laos resemble southern African Diploglena, rather than the type genus Caponia. However, members of Diploglena (which are poorly known, and are therefore discussed and illustrated) have an endite shape and eye pattern indicating that they may be most closely related to the Chilean genus Tisentnops. Laoponia may be most closely related instead to the endemic Californian genus Calponia; similar California/East Asia disjuncts are known in other old spider lineages
A priori convergence estimates for a rough Poisson-Dirichlet problem with natural vertical boundary conditions
Stents are medical devices designed to modify blood flow in aneurysm sacs, in
order to prevent their rupture. Some of them can be considered as a locally
periodic rough boundary. In order to approximate blood flow in arteries and
vessels of the cardio-vascular system containing stents, we use multi-scale
techniques to construct boundary layers and wall laws. Simplifying the flow we
turn to consider a 2-dimensional Poisson problem that conserves essential
features related to the rough boundary. Then, we investigate convergence of
boundary layer approximations and the corresponding wall laws in the case of
Neumann type boundary conditions at the inlet and outlet parts of the domain.
The difficulty comes from the fact that correctors, for the boundary layers
near the rough surface, may introduce error terms on the other portions of the
boundary. In order to correct these spurious oscillations, we introduce a
vertical boundary layer. Trough a careful study of its behavior, we prove
rigorously decay estimates. We then construct complete boundary layers that
respect the macroscopic boundary conditions. We also derive error estimates in
terms of the roughness size epsilon either for the full boundary layer
approximation and for the corresponding averaged wall law.Comment: Dedicated to Professor Giovanni Paolo Galdi 60' Birthda
Senile plaque calcification of the lamina circumvoluta medullaris in Alzheimer's disease
Vascular calcification is a common phenomenon in the elderly, predominantly appearing in the basal ganglia and in the lamina circumvoluta medullaris of the hippocampus. Calcifications are not an inherent feature of Alzheimer's disease. On the other hand, a rare presenile type of dementia with symmetrical Fahr-type calcifications and numerous neurofibrillary tangles without senile plaques has been described by Kosaka in 1994 and was termed "diffuse neurofibrillary tangles with calcification" (DNTC). We here report a case of Alzheimer's disease with calcifications both in the basal ganglia and in the lamina circumvoluta medullaris of the hippocampus, differing from DNTC by the presence of senile plaques. The calcifications in the hippocampus were not only vascular in nature but also covered amyloid-β- and phosphorylated tau-positive plaque-like structures that were linearly arranged along the dentate fascia in the CA1 sector, an unusual finding of pathogenetic interest
On the relevance of polyynyl-substituted PAHs to astrophysics
We report on the absorption spectra of the polycyclic aromatic hydrocarbon
(PAH) molecules anthracene, phenanthrene, and pyrene carrying either an ethynyl
(-C2H) or a butadiynyl (-C4H) group. Measurements were carried out in the mid
infrared at room temperature on grains embedded in CsI pellets and in the near
ultraviolet at cryogenic temperature on molecules isolated in Ne matrices. The
infrared measurements show that interstellar populations of
polyynyl-substituted PAHs would give rise to collective features in the same
way non-substituted PAHs give rise to the aromatic infrared bands. The main
features characteristic of the substituted molecules correspond to the
acetylenic CH stretching mode near 3.05 mum and to the almost isoenergetic
acetylenic CCH in- and out-of-plane bending modes near 15.9 mum.
Sub-populations defined by the length of the polyynyl side group cause
collective features which correspond to the various acetylenic CC stretching
modes. The ultraviolet spectra reveal that the addition of an ethynyl group to
a non-substituted PAH molecule results in all its electronic transitions being
redshifted. Due to fast internal energy conversion, the bands at shorter
wavelengths are significantly broadened. Those at longer wavelengths are only
barely affected in this respect. As a consequence, their relative peak
absorption increases. The substitution with the longer butadiynyl chain causes
the same effects with a larger magnitude, resulting in the spectra to show a
prominent if not dominating pi-pi* transition at long wavelength. After
discussing the relevance of polyynyl-substituted PAHs to astrophysics, we
conclude that this class of highly conjugated, unsaturated molecules are valid
candidates for the carriers of the diffuse interstellar bands.Comment: 29 pages, 9 figures, accepted for publication in ApJ 2 April 201
Noodlottige kindermishandeling: ‘n literatuuroorsig en die profiel in die Suid-Vrystaat (1995-2003) Fatal child abuse: a literature review and the profile in the Southern Free State (1995-2003)
Agtergrond
Kindermishandeling is \'n sosiale probleem met verreikende gevolge. Ernstige onderrapportering van gevalle vind plaas, en geen studies kon opgespoor word wat die Suid-Afrikaanse konteks van die probleem ondersoek nie. In hierdie studie is gepoog om die profiel van die slagoffers van noodlottige kindermishandeling
in die Suid-Vrystaat te ondersoek.
Metodes
Alle kindersterftes van kinders van tien jaar en jonger is uit die register van sterftes by die SAPD- (Suid-Afrikaanse Polisiediens-)
lykshuis, Bloemfontein, geïdentifiseer. Hierdie sterftes se verslae is vir gevalle van noodlottige kindermishandeling geëvalueer. Irrelevante verslae is geëlimineer totdat \'n groep moontlike gevalle van noodlottige kindermishandeling verkry is. In gevalle waar daar twyfel oor die oorsaak van dood was, is \'n kliniese assistent in Geregtelike Geneeskunde geraadpleeg.
In sommige gevalle het die assistent aanbeveel dat \'n geskiedenis uit polisieverslae verkry moes word. Indien gevalle nie op so \'n wyse bevestig kon word nie, is dit in die sogenaamde ‘grys area\' ingesluit. Negentien gevalle is geïdentifiseer
en vier is in die grys area geplaas.
Resultate
Uit die 19 gevalle was die meerderheid vroulik (14). Die mediaanouderdom van slagoffers was twee jaar. Die slag-offers toon \'n eweredige verspreiding t.o.v. ras. Geen patroon
kon geïdentifiseer word in die jaarlikse en maandelikse verspreiding van sterftes nie. Die meeste van die slagoffers, 73.7% (14 van 19 gevalle), was van normale massa, en geen slagoffers het aan \'n wanvoedingsiekte gely nie. Hoofbese-rings was die algemeenste oorsaak van sterftes (63.2%), gevolg deur veelvuldige beserings (21.2%).
Gevolgtrekking
Indien dokters bedag is op die tekens van kindermishandeling,
kan gevalle vroeg geïdentifiseer word. Sodoende kan \'n beduidende verlaging in mortaliteit en morbiditeit bewerkstellig
Introduction
Child abuse is a social problem with far-reaching consequences.
Serious underreporting of cases occurs, and no studies could be found which investigates the South African context of the problem. In this study we aimed to determine the profile
of victims of fatal child abuse in the Southern Free State.
Methods
All child deaths of children 10 years and younger in the period 1 January 1995 to 31 December 2003 were identified
in the register of deaths at the SA Police Mortuary, Bloemfontein. The reports of these deaths were evaluated to identify possible cases of fatal child abuse. Irrelevant reports were eliminated until a group of possible cases of fatal child abuse were identified. In cases where there was uncertainty about the cause of death, a registrar in Forensic Medicine was consulted. In some cases she advised that a history be obtained from police reports. Cases which could not be confirmed in this way were included in a so-called grey area. Nineteen cases were identified, and a further 4 placed in the grey area.
Results
Of the 19 cases, the majority were female (14). The median age of cases was 2 years. Cases showed an even distribution
regarding race. No patterns regarding annual or monthly distribution were found. Most victims, 73.7% (14 of 19 cases), were of normal weight and no victims suffered from malnutrition. Head injuries were the most common cause of death (63.2%) followed by multiple injuries (21.2%).
Conclusion
If doctors are aware of the signs of child abuse cases can be identified early. In this way a significant decrease in mortality and morbidity can occur.
word.South African Family Practice Vol. 49 (9) 2007: pp. 1
Aperiodic invariant continua for surface homeomorphisms
We prove that if a homeomorphism of a closed orientable surface S has no
wandering points and leaves invariant a compact, connected set K which contains
no periodic points, then either K=S and S is a torus, or is the
intersection of a decreasing sequence of annuli. A version for non-orientable
surfaces is given.Comment: 8 pages, to appear in Mathematische Zeitschrif
- …