679 research outputs found
1,4-Bis(4-nitrosophenyl)piperazine: novel bridging ligand in dinuclear complexes of rhodium(III) and iridium(III).
The synthesis, spectroscopic characterization and crystal structures of the first 1,4-bis(4-nitrosophenyl)piperazine (BNPP) (4) bridged dinuclear complexes of rhodium(III) and iridium(III) are presented. The reaction of the μ2-halogenido-bridged dimers [(η5-C5Me5)IrX2]2 [X = Cl (5a), Br (5b), I (5c)] and [(η5- C5Me5)RhCl2]2 (6a) with 4 yields the dinuclear complexes [(η5-C5Me5)IrX2]2-BNPP (7a–c) and [(η5-C5Me5)RhCl2]2-BNPP (8a). All new compounds were characterized by their NMR, IR and mass spectra. The X-ray structure analyses of the obtained half-sandwich complexes revealed a slightly distorted pseudo-octahedral configuration (“three-legged pianostool”) for the metal(III) centers. The bridging BNPP ligand is σ-N coordinated by both nitroso groups and shows different conformations of the piperazine ring depending on the solvent used for crystallization. Moreover the crystal structures of 1,4-bis(4-nitrosophenyl)piperazine (4) and its precursor 1,4-diphenylpiperazine (3) are reported
Which hedge fund indices suit best for investors?
In contrast to most traditional assets, alternatives, especially hedge funds, do not have a distinct universe. This complicates proper performance measurement since most benchmarks suffer from statistical biases, deceiving investors about the "true” return an average hedge fund would have achieved. We investigate these influences, present an index for Swiss registered hedge funds which aims to avoid common biases and conclude that the systematic underperformance of funds of hedge funds compared to single hedge funds is mostly a result of bias mitigation. This indicates that the returns of fund of hedge funds indices are the most accurate for benchmarking both single- and funds of hedge funds.In contrast to most traditional assets, alternatives, especially hedge funds, do not have a distinct universe. This complicates proper performance measurement since most benchmarks suffer from statistical biases, deceiving investors about the "true” return an average hedge fund would have achieved. We investigate these influences, present an index for Swiss registered hedge funds which aims to avoid common biases and conclude that the systematic underperformance of funds of hedge funds compared to single hedge funds is mostly a result of bias mitigation. This indicates that the returns of fund of hedge funds indices are the most accurate for benchmarking both single- and funds of hedge funds
PRVI NALAZ GRINJE Histiostoma ulmi NA OBIČNOJ JELI I NAZNAKA NJEZINOG MOGUĆEG FORETIČKOG ŠIRENJA PUTEM CVILIDRETE Acanthocinus reticulatus
The mite Histiostoma ulmi (Histiostomatidae), originally discovered by the describer within the bark beetle galleries of genus Scolytus, has been found to be phoretic on a tenebrionid beetle Hypophloeus bicolor. The first discovery of H. ulmi in the galleries of the longhorn beetle Acanthocinus reticulatus indicates the possibility of its phoretic association with several beetle carriers: tenebrionid, cerambycid and scolytid beetles. In Croatia, scolytids of the genus Pityokteines, occupying the same niche within their food plant, silver fir (Abies alba) could represent these additional carriers.
Acanthocinus reticulatus infested the bark of an Abies alba specimen as a pioneer taxon, as opposed to the usual earliest colonising beetles Pityokteines spinidens and P. curvidens. Histiostoma ulmi was reared from samples taken from the galleries of this longhorn beetle’s larvae. As is typical for histiostomids, these mites feed on bacteria. They represent a monophyletic group of at least six very similar species. The morphological characters separating H. ulmi from similar species are expressed only in adult mites. Deutonymphs found attached to Pityokteines were previously determined to be Histiostoma piceae, but were never reared to adulthood. Due to a close resemblance between the deutonymphs of H. piceae and H. ulmi, incorrect assignments, relying only on deutonymphs for determination, are possible. H. ulmi was observed under laboratory conditions carrying spores of an undetermined mold fungus. Other phoretic mites, such as Tarsonemus, are known to carry spores of blue stain fungi (Ophiostomatidae) which could be of practical importance in silver fir decline. Future studies need to show, whether deutonymphs of H. ulmi, possible vectored by bark beetles, tenebrionids and longhorn beetles, also carry spores of blue stain fungi.Grinja Histiostoma ulmi (Histiostomatidae) izvorno je opisana kao vrsta koja se nalazi u hodnicima potkornjaka roda Scolytus s kojima nema foretički odnos, za razliku od kornjaša Hypophloeus bicolor iz porodice Tenebrionidae. Prvi nalaz grinje H. ulmi u hodnicima strizibuba Acanthocinus reticulatus indicira mogućnost foretičke asocijacije s nekoliko kornjaša iz porodica Tenebrionidae, Cerambycidae i Curculionidae. Na običnoj jeli (Abies alba) u Hrvatskoj potkornjaci roda Pityokteines zauzimaju istu hranidbenu nišu kao i A. reticulatus te su također mogući prijenosnici spomenutih grinja.
Acanthocinus reticulatus napadaju koru jele debla kao pionirski takson, suprotno od dosadašnjih saznanja kako Pityokteines spinidens i P. curvidens dolaze prvi.
Histiostoma ulmi sakupljana je s uzoraka uzetih od hodnika larvi strizibuba. Histiotomatidae koje se hrane bakterijama, predstavlja monofiletičku grupu sastavljenu od šest vrlo sličnih vrsta. Morfološke razlike H. ulmi sa sličnim vrstama vidljive su isključivo u stadiju imaga.
Deutonimfe nađene na vrstama roda Pityokteines u ranijim istraživanjima determinirane su, bez razvoja odraslih oblika, kao Histiostoma piceae. Glede velike sličnosti između deutonimfi H. piceae i H. ulmi, moguće je da su napravljene pogreške u identifikaciji. Histiostoma ulmi uzgajana u laboratorijskim uvjetima na tijelu je nosila neidentificirane gljive. Grinje kao primjerice Tarsonemus, poznate su kao prenositelji gljive plavila (Ophiostomatidae) koje mogu imati važnu ulogu kod odumiranja jele. Buduća istraživanja trebaju pokazati da li deutonimfe H. ulmi kojima su mogući vektori kukci rodova Cerambycidae, Tenebrionidae ili Curculionidae, također prenose spore gljive plavila
Structural investigations of CeIrIn and CeCoIn on macroscopic and atomic length scales
For any thorough investigation of complex physical properties, as encountered
in strongly correlated electron systems, not only single crystals of highest
quality but also a detailed knowledge of the structural properties of the
material are pivotal prerequisites. Here, we combine physical and chemical
investigations on the prototypical heavy fermion superconductors CeIrIn
and CeCoIn on atomic and macroscopic length scale to gain insight into
their precise structural properties. Our approach spans from enhanced
resolution X-ray diffraction experiments to atomic resolution by means of
Scanning Tunneling Microscopy (STM) and reveal a certain type of local features
(coexistence of minority and majority structural patterns) in the tetragonal
HoCoGa-type structure of both compounds.Comment: 8 pages, 5 figures, submitted to JPSJ (SCES 2013
Phylogenie, Biologie und Merkmals-Transformationen der Histiostomatidae (Acari, Astigmata)
TITLEPAGE
TABLE OF CONTENTS
ABSTRACT
INTRODUCTION
MATERIAL AND METHODS
CLADOGRAM OF THE HISTIOSTOMATIDAE
STEM SPECIES PATTERN
CH-06-MORPHOLOGY AND CHARACTER TRANSFORMATIONS
HABITATS
BIOLOGY
ACKNOWLEDGEMENTS
REFERENCESThe cladogram of the monophyletic Histiostomatidae, a subgroup of the
Astigmata, was reconstructed with aid of morphological characters. The stem
species pattern which consists of all apomorphies and important plesiomorphies
of the stem species is presented. Other important apomorphies of basically
branching taxa in the reconstructed tree were discovered: In the stem species
of Bonomoia the light sensitive organs in the deutonymph were conspicuously
formed. I assume the homology of these structures to the "lenticulus" of
"oribatid" mites. In the stem species of the sister group of Bonomoia
(including all other Histiostomatidae) dorsal sclerotisations of larva and
protonymph evolved. I described the conspicuous new species Histiostoma
palustre, that possesses two male morphs. Environmental conditions
(temperature) were responsible for the development of these two morphs. Legs
II of the heteromorphic type are modified into conspicuous clasp organs, which
were used during fights of males for the females. Male diphenism influenced by
temperature conditions also appear in Histiostoma pulchrum, the closely
related H. n. sp. and H. feroniarum. By mapping these biological characters on
the tree it became obvious that male diphenisms evolved once within the
Histiostomatidae. The species Histiostoma polypori and H. maritimum differ
from most other histiostomatids by growing up only on insect cadavers of their
carriers. These species� biology obviously derived from the phoresy and is
termed necromeny and evolved twice convergently within the Histiostomatidae.Das Kladogramm der monophyletischen Histiostomatidae wurde mit Hilfe
morphologischer Merkmale rekonstruiert. Das Stammartmuster, das alle
Apomorphien und Plesiomorphien der Stammart beinhaltet, wird vorgestellt.
Wichtige Apomorphien in der Basis des Stammbaumes werden erläutert: In der
Stammart von Bonomoia sind auffällige Lichtsinnesorgane in der Deutonymphe
entstanden. Eine Homologie dieser Strukturen mit dem "Lenticulus" beiden
paraphyletischen Oribatida wird vermutet. Weitere auffällige Apomorphien
betreffen dorsale Sklerite an Larve und Protonymphe, die in der
Schwestergruppe von Bonomoia (die alle anderen Histiostomatidae beinhaltet)
evolvierten. In der von mir beschriebenen Histiostoma palustre treten
unterschiedlich gestaltete Männchen-Morphen auf. Umweltfaktoren (Temperatur)
sind für die Induktion der abgewandelten Morphe verantwortlich. Die zweiten
Beine des heteromorphen Typs wurden abgewandelt zu einem auffälligen
Klammerorgan, das eingesetzt wird im Kampf der Männchen um die Weibchen.
Temperatur abhängige Diphänismen der Männchen treten auch auf in Histiostoma
pulchrum und der nahe verwandten H. n. sp., sowie H. feroniarum. Beim
Auftragen dieser Merkmale auf den bestehenden Stammbaum wird deutlich, daß
Diphenismen der Männchen einmal innerhalb der Histiostomatidae entstanden
sind. Die Arten Histiostoma polypori und H. maritimum unterscheiden sich von
anderen Histiostomatiden durch die Tatsache, daß sie sich ausschließlich auf
Insektenkadavern ihrer Transporteure entwickeln. Die Biologie dieser Arten
leitet sich von der Phoresie ab und wird als Nekromenie bezeichnet. Sie ist
zweimal konvergent innerhalb der Histiostomatidae evolviert
Radiation protection at CERN
This paper gives a brief overview of the general principles of radiation
protection legislation; explains radiological quantities and units, including
some basic facts about radioactivity and the biological effects of radiation;
and gives an overview of the classification of radiological areas at CERN,
radiation fields at high-energy accelerators, and the radiation monitoring
system used at CERN. A short section addresses the ALARA approach used at CERN.Comment: 22 pages, contribution to the CAS - CERN Accelerator School: Course
on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai
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