536 research outputs found
Tetra-n-butylamine(carbonato-kappa O-2,O')cobalt(III)n-butylcarbamate dihydrate
The title compound, [Co(CO3)(C4H11N)4](C5H10NO2)·2H2O, is a coordination complex with an N4O2 coordination sphere around the central CoIII ion. The small bite angle of the chelating carbonate causes a distortion of the octahedral geometry to an approximately C2v local symmetry. Hydrogen-bonding between the carbonate, carbamate and amine groups, and the water of crystallization, results in a complex two-dimensional network
Mesolithic and Neolithic Subsistence in Denmark: new stable isotope data
The change in subsistence at the Mesolithic/Neolithic transition in Denmark is often characterized as rapid, with a dramatic shift from a marine diet in the Mesolithic to a terrestrial-based diet in the Neolithic. This view has been largely based on the work of Tauber (1981), who observed this dietary shift in stable carbon isotope values for human bone from various coastal sites. Crucial to Tauber's argument are the radiocarbon dates he obtained for each of the isotope samples, for the ages are used to categorize samples as Mesolithic or Neolithic. In this reassessment of his pioneering work, we report on new carbon and nitrogen stable isotope values and radiocarbon dates for Danish Mesolithic and Neolithic humans, including some obtained by remeasuring a number of Tauber's samples. We first briefly describe the Late Mesolithic and Early Neolithic in Denmark and the major characteristics of the transition. We next consider the work by Tauber that has been seminal in studies of the transition. In subsequent sections we present new radiocarbon dates and stable isotope measurements from human skeletal material from the Mesolithic and Neolithic. The concluding discussion summarizes our results and emphasizes the need for more analyses of radio- and stable isotopes from this important transition period
The four horses of an Iron Age apocalypse: war-horses from the third-century weapon sacrifice at Illerup Aadal (Denmark)
The Illerup Aadal weapon sacrifice mirrors the material world of a Germanic army from c. AD 210. Apart from the personal equipment and the weaponry of more than 400 warriors, it comprises four horses. The present paper gives the first conclusive analysis of the skeletal remains of these animals, involving osteological investigation and strontium isotope analysis. The results shed new light on the character of the sacrificial ceremonies which unfolded in the aftermath of Iron Age battles; on the nature of cavalry and its significance in Iron Age warfare; and on the much debated question as to where the army of Illerup Aadal had originally come from
Das bandkeramische Gräberfeld vom „Viesenhäuser Hof“ bei Stuttgart-Mühlhausen: Neue Untersuchungsergebnisse zum Migrationsverhalten im frühen Neolithikum
Einleitung: Gegenstand des vorliegenden Beitrags ist die Rolle der Mobilität im Leben der frühen Ackerbauern
und Viehzüchter in Südwestdeutschland. Seit Jahrzehnten werden wissenschaftliche Auseinandersetzungen
über die Bedeutung von Wanderungsbewegungen bei der Ausbreitung der produzierenden Wirtschaftsweise in Europa zwischen 7000 und 4000 v. Chr. geführt. Dabei gehen traditionelle Überlegungen davon aus, dass die ersten Ackerbauern in Mitteleuropa Zuwanderer waren, die ein
‚Paket‘ neuer Errungenschaften und Ideen mit sich führten, das u. a. Haustiere, dauerhafte Siedlungen, Keramik und den Ackerbau enthielt.1 Neuere Untersuchungen und Überlegungen gestehen dagegen der einheimischen Bevölkerung eine maßgebliche Bedeutung bei der Übernahme der neolithischen
Wirtschaftsweise zu.2 Die Mobilität des Menschen ist aber nicht nur für die Erklärung des Neolithisierungsprozesses, sondern auch für das Verständnis der Lebens- und Wirtschaftsweise der Menschen in den mittleren und späteren Abschnitten der Linearbandkeramik von höchstem
Interesse.
Die bisherige Forschungsdiskussion basierte in diesem Zusammenhang überwiegend auf indirekten Argumenten, d. h. auf Artefakten, die auch getauscht oder gestohlen worden sein konnten, aber nicht auf den Überresten der potenziellen Zuwanderer selbst, die in Form von Knochen und Zähnen erhalten sind.
Die vorliegende Studie bedient sich der direkten Analyse menschlicher Skelettreste der bandkeramischen Gräber vom ‚Viesenhäuser Hof‘, Stuttgart-Mühlhausen, mittels anthropologischer Untersuchungen und Strontiumisotopenanalysen. Nachfolgend werden der Fundplatz in seinem archäologischen Kontext der Linearbandkeramik sowie die Ergebnisse der anthropologischen Untersuchungen
und Strontiumisotopenanalysen vorgestellt und dann die Rolle der Mobilität im Leben der frühen Ackerbauern und Viehzüchter sowie für die Ausbreitung der neolithischen Wirtschaftsweise diskutiert.
Stuttgart-Mühlhausen ist eines der ältesten bandkeramischen Gräberfelder, die bislang für derartige Untersuchungen zur Verfügung standen
T violation and the unidirectionality of time
An increasing number of experiments at the Belle, BNL, CERN, DA{\Phi}NE and
SLAC accelerators are confirming the violation of time reversal invariance (T).
The violation signifies a fundamental asymmetry between the past and future and
calls for a major shift in the way we think about time. Here we show that
processes which violate T symmetry induce destructive interference between
different paths that the universe can take through time. The interference
eliminates all paths except for two that represent continuously forwards and
continuously backwards time evolution. Evidence from the accelerator
experiments indicates which path the universe is effectively following. This
work may provide fresh insight into the long-standing problem of modeling the
dynamics of T violation processes. It suggests that T violation has previously
unknown, large-scale physical effects and that these effects underlie the
origin of the unidirectionality of time. It may have implications for the
Wheeler-DeWitt equation of canonical quantum gravity. Finally it provides a
view of the quantum nature of time itself.Comment: 24 pages, 5 figures. Final version accepted for publishing in
Foundations of Physics. The final publication is available at
http://www.springerlink.com/content/y3h4174jw2w78322
Exploitation of conserved eukaryotic host cell farnesylation machinery by an F-box effector of Legionella pneumophila
Farnesylation involves covalent linkage of eukaryotic proteins to a lipid moiety to anchor them into membranes, which is essential for the biological function of Ras and other proteins. A large cadre of bacterial effectors is injected into host cells by intravacuolar pathogens through elaborate type III–VII translocation machineries, and many of these effectors are incorporated into the pathogen-containing vacuolar membrane by unknown mechanisms. The Dot/Icm type IV secretion system of Legionella pneumophila injects into host cells the F-box effector Ankyrin B (AnkB), which functions as platforms for the docking of polyubiquitinated proteins to the Legionella-containing vacuole (LCV) to enable intravacuolar proliferation in macrophages and amoeba. We show that farnesylation of AnkB is indispensable for its anchoring to the cytosolic face of the LCV membrane, for its biological function within macrophages and Dictyostelium discoideum, and for intrapulmonary proliferation in mice. Remarkably, the protein farnesyltransferase, RCE-1 (Ras-converting enzyme-1), and isoprenyl cysteine carboxyl methyltransferase host farnesylation enzymes are recruited to the LCV in a Dot/Icm-dependent manner and are essential for the biological function of AnkB. In conclusion, this study shows novel localized recruitment of the host farnesylation machinery and its anchoring of an F-box effector to the LCV membrane, and this is essential for biological function in vitro and in vivo
Identifying topological edge states in 2D optical lattices using light scattering
We recently proposed in a Letter [Physical Review Letters 108 255303] a novel
scheme to detect topological edge states in an optical lattice, based on a
generalization of Bragg spectroscopy. The scope of the present article is to
provide a more detailed and pedagogical description of the system - the
Hofstadter optical lattice - and probing method. We first show the existence of
topological edge states, in an ultra-cold gas trapped in a 2D optical lattice
and subjected to a synthetic magnetic field. The remarkable robustness of the
edge states is verified for a variety of external confining potentials. Then,
we describe a specific laser probe, made from two lasers in Laguerre-Gaussian
modes, which captures unambiguous signatures of these edge states. In
particular, the resulting Bragg spectra provide the dispersion relation of the
edge states, establishing their chiral nature. In order to make the Bragg
signal experimentally detectable, we introduce a "shelving method", which
simultaneously transfers angular momentum and changes the internal atomic
state. This scheme allows to directly visualize the selected edge states on a
dark background, offering an instructive view on topological insulating phases,
not accessible in solid-state experiments.Comment: 17 pages, 10 figures. Revised and extended version, to appear in EJP
Special Topic for the special issue on "Novel Quantum Phases and Mesoscopic
Physics in Quantum Gases". Extended version of arXiv:1203.124
Diagnosis of aortic graft infection : a case definition by the management of aortic graft infection collaboration (MAGIC)
Objective/Background
The management of aortic graft infection (AGI) is highly complex and in the absence of a universally accepted case definition and evidence-based guidelines, clinical approaches and outcomes vary widely. The objective was to define precise criteria for diagnosing AGI.
Methods
A process of expert review and consensus, involving formal collaboration between vascular surgeons, infection specialists, and radiologists from several English National Health Service hospital Trusts with large vascular services (Management of Aortic Graft Infection Collaboration [MAGIC]), produced the definition.
Results
Diagnostic criteria from three categories were classified as major or minor. It is proposed that AGI should be suspected if a single major criterion or two or more minor criteria from different categories are present. AGI is diagnosed if there is one major plus any criterion (major or minor) from another category. (i) Clinical/surgical major criteria comprise intraoperative identification of pus around a graft and situations where direct communication between the prosthesis and a nonsterile site exists, including fistulae, exposed grafts in open wounds, and deployment of an endovascular stent-graft into an infected field (e.g., mycotic aneurysm); minor criteria are localized AGI features or fever ≥38°C, where AGI is the most likely cause. (ii) Radiological major criteria comprise increasing perigraft gas volume on serial computed tomography (CT) imaging or perigraft gas or fluid (≥7 weeks and ≥3 months, respectively) postimplantation; minor criteria include other CT features or evidence from alternative imaging techniques. (iii) Laboratory major criteria comprise isolation of microorganisms from percutaneous aspirates of perigraft fluid, explanted grafts, and other intraoperative specimens; minor criteria are positive blood cultures or elevated inflammatory indices with no alternative source.
Conclusion
This AGI definition potentially offers a practical and consistent diagnostic standard, essential for comparing clinical management strategies, trial design, and developing evidence-based guidelines. It requires validation that is planned in a multicenter, clinical service database supported by the Vascular Society of Great Britain & Ireland
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
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