7,315 research outputs found
On <i>Klieopsis</i> n. gen., with a description of <i>Cypridopsis horai</i> Klie, 1927 (Crustacea, Ostracoda)
Klieopsis n. gen. is here described to comprise the species Cypridopsis horai Klie, reported from India. The new genus is characterized by an aberrant inner list on the RV, by a furca with a cylindrical trunk and by the reduction of two claws (G2 and Gm) on the A2 to short setae. After re-examination of the type materials, Cypridopsis caerulescens Klie from Kenya is synonymized with K. horai, which is here furthermore reported for the first time from Israel (surroundings of the Dead Sea). The latter specimens are extensively described, and a discussion on the taxonomic position of the new genus is offered. An apparently similar species from Sardegna, Cypridopsis thermarum Tagliasacchi-Masala, 1968, is here formally referred to Plesiocypridopsis
Macroscopic effects in attosecond pulse generation
We examine how the generation and propagation of high-order harmonics in a
partly ionized gas medium affect their strength and synchronization. The
temporal properties of the resulting attosecond pulses generated in long gas
targets can be significantly influenced by macroscopic effects, in particular
by the intensity in the medium and the degree of ionization. Under some
conditions, the use of gas targets longer than the absorption length can lead
to the generation of self-compressed attosecond pulses. We show this effect
experimentally, using long argon-filled gas cells as generating medium.Comment: 5 pages 4 figure
Protein processing characterized by a gel-free proteomics approach
We describe a method for the specific isolation of representative N-terminal peptides of proteins and their proteolytic fragments. Their isolation is based on a gel-free, peptidecentric proteomics approach using the principle of diagonal chromatography. We will indicate that the introduction of an altered chemical property to internal peptides holding a free α-N-terminus results in altered column retention of these peptides, thereby enabling the isolation and further characterization by mass spectrometry of N-terminal peptides. Besides pointing to changes in protein expression levels when performing such proteome surveys in a differential modus, protease specificity and substrate repertoires can be allocated since both are specified by neo-N-termini generated after a protease cleavage event. As such, our gel-free proteomics technology is widely applicable and amenable for a variety of proteome-driven protease degradomics research
Driven Brownian transport through arrays of symmetric obstacles
We numerically investigate the transport of a suspended overdamped Brownian
particle which is driven through a two-dimensional rectangular array of
circular obstacles with finite radius. Two limiting cases are considered in
detail, namely, when the constant drive is parallel to the principal or the
diagonal array axes. This corresponds to studying the Brownian transport in
periodic channels with reflecting walls of different topologies. The mobility
and diffusivity of the transported particles in such channels are determined as
functions of the drive and the array geometric parameters. Prominent transport
features, like negative differential mobilities, excess diffusion peaks, and
unconventional asymptotic behaviors, are explained in terms of two distinct
lengths, the size of single obstacles (trapping length) and the lattice
constant of the array (local correlation length). Local correlation effects are
further analyzed by continuously rotating the drive between the two limiting
orientations.Comment: 10 pages 13 figure
Advances towards reliable identification and concentration determination of rare cells in peripheral blood
Through further development, integration and validation of micro-nano-bio and biophotonics systems FP7 CanDo is developing an instrument that will permit highly reproducible and reliable identification and concentration determination of rare cells in peripheral blood for two key societal challenges, early and low cost anti-cancer drug efficacy determination and cancer diagnosis/monitoring. A cellular link between the primary malignant tumour and the peripheral metastases, responsible for 90% of cancerrelated deaths, has been established in the form of circulating tumour cells (CTCs) in peripheral blood. Furthermore, the relatively short survival time of CTCs in peripheral blood means that their detection is indicative of tumour progression thereby providing in addition to a prognostic value an evaluation of therapeutic efficacy and early recognition of tumour progression in theranostics. In cancer patients however blood concentrations are very low (=1 CTC/1E9 cells) and current detection strategies are too insensitive, limiting use to prognosis of only those with advanced metastatic cancer. Similarly, problems occur in therapeutics with anti-cancer drug development leading to lengthy and costly trials often preventing access to market. The novel cell separation/Raman analysis technologies plus nucleic acid based molecular characterization of the CanDo platform will provide an accurate CTC count with high throughput and high yield meeting both key societal challenges. Being beyond the state of art it will lead to substantial share gains not just in the high end markets of drug discovery and cancer diagnostics but due to modular technologies also in others. Here we present preliminary DNA hybridization sensing results
Maximal Accuracy and Minimal Disturbance in the Arthurs-Kelly Simultaneous Measurement Process
The accuracy of the Arthurs-Kelly model of a simultaneous measurement of
position and momentum is analysed using concepts developed by Braginsky and
Khalili in the context of measurements of a single quantum observable. A
distinction is made between the errors of retrodiction and prediction. It is
shown that the distribution of measured values coincides with the initial state
Husimi function when the retrodictive accuracy is maximised, and that it is
related to the final state anti-Husimi function (the P representation of
quantum optics) when the predictive accuracy is maximised. The disturbance of
the system by the measurement is also discussed. A class of minimally
disturbing measurements is characterised. It is shown that the distribution of
measured values then coincides with one of the smoothed Wigner functions
described by Cartwright.Comment: 12 pages, 0 figures. AMS-Latex. Earlier version replaced with final
published versio
Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance
A liquid isooctane (CH) filled ionization linear array for
radiotherapy quality assurance has been designed, built and tested. The
detector consists of 128 pixels, each of them with an area of 1.7 mm
1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for
high gradient beam profiles like those present in Intensity Modulated Radiation
Therapy (IMRT) and radiosurgery. As read-out electronics we use the X-Ray Data
Acquisition System (XDAS) with the Xchip developed by the CCLRC.
Studies concerning the collection efficiency dependence on the polarization
voltage and on the dose rate have been made in order to optimize the device
operation.
In the first tests we have studied dose rate and energy dependences, and
signal reproducibility. Dose rate dependence was found lower than 2.5 % up to 5
Gy min, and energy dependence lower than 2.1 % up to 20 cm depth in
solid water. Output factors and penumbras for several rectangular fields have
been measured with the linear array and were compared with the results obtained
with a 0.125 cm air ionization chamber and radiographic film,
respectively. Finally, we have acquired profiles for an IMRT field and for a
virtual wedge. These profiles have also been compared with radiographic film
measurements. All the comparisons show a good correspondence. Signal
reproducibility was within a 2% during the test period (around three months).
The device has proved its capability to verify on-line therapy beams with
good spatial resolution and signal to noise ratio.Comment: 16 pages, 12 figures Submitted to Phys. Med. Bio
Phase space reduction of the one-dimensional Fokker-Planck (Kramers) equation
A pointlike particle of finite mass m, moving in a one-dimensional viscous
environment and biased by a spatially dependent force, is considered. We
present a rigorous mapping of the Fokker-Planck equation, which determines
evolution of the particle density in phase space, onto the spatial coordinate
x. The result is the Smoluchowski equation, valid in the overdamped limit,
m->0, with a series of corrections expanded in powers of m. They are determined
unambiguously within the recurrence mapping procedure. The method and the
results are interpreted on the simplest model with no field and on the damped
harmonic oscillator.Comment: 13 pages, 1 figur
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