1,082 research outputs found
A simplified protocol for detecting two systemic bait markers (Rhodamine B and iophenoxic acid) in small mammals
We developed a method of quantifying levels of fluorescence in the whiskers of wild stoats (Mustela erminea) using fluorescence microscopy and Axiovision 3.0.6.1 software. The method allows for discrimination between natural fluorescence present in or on a whisker, and the fluorescence resulting from the ingestion of the systemic marker Rhodamine B (RB), although some visual judgement is still required. We also developed a new high performance liquid chromatography (HPLC) protocol for detecting the systemic marker iophenoxic acid (IPA) in the blood of laboratory rats (Rattus norvegicus) and wild stoats. With this method, the blood of an animal that has consumed IPA can be tested for the presence of the foreign IPA compound itself. This is a more reliable test than the previous method, which measured the raised level of natural blood protein-bound iodine correlated with IPA absorption. The quantity of blood required from animal subjects is very small (10 ÎŒl), so the testing is less intrusive and the method can be extended to smaller species. The extraction technique uses methanol, rather than acids and heavy metal salts, thereby simplifying the procedure. Recovery of IPA is quantitative, giving a highly reliable reading. In experiments on captive rats the IPA method proved successful. Of 12 positively marked carcasses, two that had not been frozen for the 24 h before blood samples were taken showed relatively lower IPA levels. The same IPA detection method, as well as the whisker analysis for RB, was applied successfully to a population of wild stoats to which both Rhodamine B and IPA were made available at bait stations. The presence of both bait markers was detectable in rats for at least 21 days and in stoats for at least 27 days
Programmable logic circuits for functional integrated smart plastic systems
In this paper, we present a functional integrated plastic system. We have fabricated arrays of organic thin-film transistors (OTFTs) and printed electronic components driving an electrophoretic ink display up to 70mm by 70mm on a single flexible transparent plastic foil. Transistor arrays were quickly and reliably configured for different logic functions by an additional process step of inkjet printing conductive silver wires and poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) resistors between transistors or between logic blocks. Among the circuit functions and features demonstrated on the arrays are a 7-stage ring oscillator, a D-type ip-flop memory element, a 2:4 demultiplexer, a programmable array logic device (PAL), and printed wires and resistors. Touch input sensors were also printed, thus only external batteries were required for a complete electronic subsystem. The PAL featured 8 inputs, 8 outputs, 32 product terms, and had 1260 p-type polymer transistors in a 3-metal process using diode-load logic. To the best of our knowledge, this is the first time that a PAL concept with organic transistors has been demonstrated, and also the first time that organic transistors have been used as the control logic for a flexible display which have both been integrated on to a single plastic substrate. The versatility afforded by the additive inkjet printing process is well suited to organic programmable logic on plastic substrates, in effect, making flexible organic electronics more flexibleRCUK, OtherThis is the final published version. It is also available from Elsevier at http://www.sciencedirect.com/science/article/pii/S1566119914003607#
Setting limits on Effective Field Theories: the case of Dark Matter
The usage of Effective Field Theories (EFT) for LHC new physics searches is
receiving increasing attention. It is thus important to clarify all the aspects
related with the applicability of the EFT formalism in the LHC environment,
where the large available energy can produce reactions that overcome the
maximal range of validity, i.e. the cutoff, of the theory. We show that this
does forbid to set rigorous limits on the EFT parameter space through a
modified version of the ordinary binned likelihood hypothesis test, which we
design and validate. Our limit-setting strategy can be carried on in its
full-fledged form by the LHC experimental collaborations, or performed
externally to the collaborations, through the Simplified Likelihood approach,
by relying on certain approximations. We apply it to the recent CMS mono-jet
analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a
case study because the limited reach on the DM production EFT Wilson
coefficient and the structure of the theory suggests that the cutoff might be
dangerously low, well within the LHC reach. However our strategy can also be
applied to EFT's parametrising the indirect effects of heavy new physics in the
Electroweak and Higgs sectors
Programmable logic circuits for functional integrated smart plastic systems
In this paper, we present a functional integrated plastic system. We have fabricated arrays of organic thin-film transistors (OTFTs) and printed electronic components driving an electrophoretic ink display up to 70 mm by 70 mm on a single flexible transparent plastic foil. Transistor arrays were quickly and reliably configured for different logic functions by an additional process step of inkjet printing conductive silver wires and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) resistors between transistors or between logic blocks. Among the circuit functions and features demonstrated on the arrays are a 7-stage ring oscillator, a D-type flip-flop memory element, a 2:4 demultiplexer, a programmable array logic device (PAL), and printed wires and resistors. Touch input sensors were also printed, thus only external batteries were required for a complete electronic subsystem. The PAL featured 8 inputs, 8 outputs, 32 product terms, and had 1260 p-type polymer transistors in a 3-metal process using diode-load logic. To the best of our knowledge, this is the first time that a PAL concept with organic transistors has been demonstrated, and also the first time that organic transistors have been used as the control logic for a flexible display which have both been integrated on to a single plastic substrate. The versatility afforded by the additive inkjet printing process is well suited to organic programmable logic on plastic substrates, in effect, making flexible organic electronics more flexible. Crown Copyright (C) 2014 Published by Elsevier B.V.X113426Ysciescopu
Synthesis, Evaluation and Structural Studies of Antiproliferative Tubulin-targeting Azetidin-2-ones
A series of azetidin-2-ones substituted at positions 2, 3 and 4 of the azetidinone ring scaffold were synthesised and evaluated for antiproliferative, cytotoxic and tubulin binding activity. In these compounds, the cis double bond of the vascular targeting agent combretastatin A-4 is replaced with the azetidinone ring in order to enhance the antiproliferative effects displayed by combretastatin A-4 and prevent the cis/trans isomerization that is associated with inactivation of combretastatin A-4. The series of azetidinones was synthetically accessible via the Staudinger and Reformatsky reactions. Of a diverse range of heterocyclic derivatives, 3-(2-thienyl) analogue 28 and 3-(3-thienyl) analogue 29 displayed the highest potency in human MCF-7 breast cancer cells with IC50 values of 7nM and 10nM respectively, comparable to combretastatin A-4. Compounds from this series also exhibited potent activity in MDA-MB-231 breast cancer cells and in the NCI60 cell line panel. No significant toxicity was observed in normal murine breast epithelial cells. The presence of larger, bulkier groups at the 3-position, for example 3-naphthyl derivative 21 and 3-benzothienyl derivative 26, resulted in relatively lower antiproliferative activity in the micromolar range. Tubulin-binding studies of 28 (IC50=1.37ÎŒM) confirmed that the molecular target of this series of compounds is tubulin. These novel 3-(thienyl) ÎČ-lactam antiproliferative agents are useful scaffolds for the development of tubulin-targeting drugs
Virtual signatures of dark sectors in Higgs couplings
Where collider searches for resonant invisible particles loose steam, dark
sectors might leave their trace as virtual effects in precision observables.
Here we explore this option in the framework of Higgs portal models, where a
sector of dark fermions interacts with the standard model through a strong
renormalizable coupling to the Higgs boson. We show that precise measurements
of Higgs-gauge and triple Higgs interactions can probe dark fermions up to the
TeV scale through virtual corrections. Observation prospects at the LHC and
future lepton colliders are discussed for the so-called singlet-doublet model
of Majorana fermions, a generalization of the bino-higgsino scenario in
supersymmetry. We advocate a two-fold search strategy for dark sectors through
direct and indirect observables.Comment: 20 pages, 7 figures, 1 tabl
Towards surface quantum optics with Bose-Einstein condensates in evanescent waves
We present a surface trap which allows for studying the coherent interaction
of ultracold atoms with evanescent waves. The trap combines a magnetic Joffe
trap with a repulsive evanescent dipole potential. The position of the magnetic
trap can be controlled with high precision which makes it possible to move
ultracold atoms to the surface of a glass prism in a controlled way. The
optical potential of the evanescent wave compensates for the strong attractive
van der Waals forces and generates a potential barrier at only a few hundred
nanometers from the surface. The trap is tested with Rb Bose-Einstein
condensates (BEC), which are stably positioned at distances from the surfaces
below one micrometer
Using atomic interference to probe atom-surface interaction
We show that atomic interference in the reflection from two suitably
polarized evanescent waves is sensitive to retardation effects in the
atom-surface interaction for specific experimental parameters. We study the
limit of short and long atomic de Broglie wavelength. The former case is
analyzed in the semiclassical approximation (Landau-Zener model). The latter
represents a quantum regime and is analyzed by solving numerically the
associated coupled Schroedinger equations. We consider a specific experimental
scheme and show the results for rubidium (short wavelength) and the much
lighter meta-stable helium atom (long wavelength). The merits of each case are
then discussed.Comment: 11 pages, including 6 figures, submitted to Phys. Rev. A, RevTeX
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Exploring the van der Waals Atom-Surface attraction in the nanometric range
The van der Waals atom-surface attraction, scaling as C3 z-3 for z the
atom-surface distance, is expected to be valid in the distance range 1-1000 nm,
covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour
nanocell allows us to analyze the spectroscopic modifications induced by the
atom-surface attraction on the 6P3/2->6D5/2 transition. The measured C3 value
is found to be independent of the thickness in the explored range 40-130 nm,
and is in agreement with an elementary theoretical prediction. We also discuss
the specific interest of exploring short distances and large interaction
energy.Comment: to appear in Europhysics Letter
High contrast D line electromagnetically induced transparency in nanometric-thin rubidium vapor cell
Electromagnetically induced transparency (EIT) on atomic D line of
rubidium is studied using a nanometric-thin cell with atomic vapor column
length in the range of L= 400 - 800 nm. It is shown that the reduction of the
cell thickness by 4 orders as compared with an ordinary cm-size cell still
allows to form an EIT resonance for ( nm) with the
contrast of up to 40%. Remarkable distinctions of EIT formation in
nanometric-thin and ordinary cells are demonstrated. Despite the Dicke effect
of strong spectral narrowing and increase of the absorption for , EIT resonance is observed both in the absorption and the fluorescence
spectra for relatively low intensity of the coupling laser. Well resolved
splitting of the EIT resonance in moderate magnetic field for
can be used for magnetometry with nanometric spatial resolution. The presented
theoretical model well describes the observed results.Comment: Submitted to Applied Physics B: Lasers and Optics, 9 pages, 10
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