Compression of sub-relativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction

We demonstrate compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching as a result of a velocity chirp, induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs

Highly divergent CRESS DNA and picorna-like viruses associated with bleached thalli of the green seaweed <i>Ulva</i>

Marine macroalgae (seaweeds) are important primary producers and foundation species in coastal ecosystems around the world. Seaweeds currently contribute to an estimated 51% of the global mariculture production, with a long-term growth rate of 6% per year, and an estimated market value of more than US$11.3 billion. Viral infections could have a substantial impact on the ecology and aquaculture of seaweeds, but surprisingly little is known about virus diversity in macroalgal hosts. Using metagenomic sequencing, we characterized viral communities associated with healthy and bleached specimens of the commercially important green seaweed Ulva. We identified 20 putative new and divergent viruses, of which the majority belonged to the Circular Rep-Encoding Single-Stranded (CRESS) DNA viruses [single-stranded (ss)DNA genomes], Durnavirales [double-stranded (ds)RNA], and Picornavirales (ssRNA). Other newly identified RNA viruses were related to the Ghabrivirales, the Mitoviridae, and the Tombusviridae. Bleached Ulva samples contained particularly high viral read numbers. While reads matching assembled CRESS DNA viruses and picorna-like viruses were nearly absent from the healthy Ulva samples (confirmed by qPCR), they were very abundant in the bleached specimens. Therefore, bleaching in Ulva could be caused by one or a combination of the identified viruses but may also be the result of another causative agent or abiotic stress, with the viruses simply proliferating in already unhealthy seaweed tissue. This study highlights how little we know about the diversity and ecology of seaweed viruses, especially in relation to the health and diseases of the algal host, and emphasizes the need to better characterize the algal virosphere. IMPORTANCE Green seaweeds of the genus Ulva are considered a model system to study microbial interactions with the algal host. Remarkably little is known, however, about viral communities associated with green seaweeds, especially in relation to the health of the host. In this study, we characterized the viral communities associated with healthy and bleached Ulva. Our findings revealed the presence of 20 putative novel viruses associated with Ulva, encompassing both DNA and RNA viruses. The majority of these viruses were found to be especially abundant in bleached Ulva specimens. This is the first step toward understanding the role of viruses in the ecology and aquaculture of this green seaweed.</p

Three-phase mass transfer in pillared micro channels

no abstrac

SMT-based Model Checking for Recursive Programs

We present an SMT-based symbolic model checking algorithm for safety verification of recursive programs. The algorithm is modular and analyzes procedures individually. Unlike other SMT-based approaches, it maintains both "over-" and "under-approximations" of procedure summaries. Under-approximations are used to analyze procedure calls without inlining. Over-approximations are used to block infeasible counterexamples and detect convergence to a proof. We show that for programs and properties over a decidable theory, the algorithm is guaranteed to find a counterexample, if one exists. However, efficiency depends on an oracle for quantifier elimination (QE). For Boolean Programs, the algorithm is a polynomial decision procedure, matching the worst-case bounds of the best BDD-based algorithms. For Linear Arithmetic (integers and rationals), we give an efficient instantiation of the algorithm by applying QE "lazily". We use existing interpolation techniques to over-approximate QE and introduce "Model Based Projection" to under-approximate QE. Empirical evaluation on SV-COMP benchmarks shows that our algorithm improves significantly on the state-of-the-art.Comment: originally published as part of the proceedings of CAV 2014; fixed typos, better wording at some place

Переходная зона между шельфом и континентальным склоном северной части Чёрного моря. Ландшафтный подход

На основе данных, полученных с применением обитаемых подводных аппаратов, рассмотрена проблема положения бровки шельфа как важной структурно фациальной границы морского бассейна. Описана ландшафтная фациальная зональность в диапазоне глубин 70–220 м в северной части Черного моря. Выявлено, что смена фаций в переходной зоне между шельфом и материковым склоном от бровки шельфа до глубины около 200 м находится в тесной связи с усилением гипоксии до полной аноксии.На основі даних, отриманих із застосуванням підводних апаратів, розглянуто проблему положення бровки шельфу як важливої структурно фаціальної межі морського басейну. Описано ландшафтну фаціальну зональність в діапазоні глибин 70–20 м у північній частині Чорного моря. Виявлено, що зміна фацій у перехідній зоні між шельфом і материковим схилом від бровки шельфу до глибини близько 200 м тісно пов’язана із збільшенням гіпоксії до повної аноксії.The problem of continental shelf break position as an important structural – facial marine basin boundary discussed on the basis of manned submersibles’ data. The range and setting of Northern Black Sea facial zones in the depths interval 70 220m are described. It’s found that the facial changes are related closely with hypoxia increasing to complete anoxia from the shelf break to the depth of about 200 m

Three-phase mass transfer in pillared micro channels

no abstrac

An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 106 per shot for a 100 period undulator, with a mean peak brilliance of 1 × 1018 photons/s/mrad2/mm2/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs

Measurement of fraction unbound paclitaxel in human plasma

The clinical pharmacokinetic behavior of paclitaxel (Taxol) is distinctly nonlinear, with disproportional increases in systemic exposure with an increase in dose. We have recently shown that Cremophor EL, the formulation vehicle used for i.v. administration of paclitaxel, alters drug distribution as a result of micellar entrapment of paclitaxel, and we speculated that the free drug fraction (fu) is dependent on dose and time-varying concentrations of Cremophor EL in the central plasma compartment. To test this hypothesis, a reproducible equilibrium dialysis method has been developed for the measurement of paclitaxel fu in plasma. Equilibrium dialysis was performed at 37 degrees C in a humidified atmosphere of 5% CO(2) using 2.0-ml polypropylene test tubes. Experiments were carried out with 260-microliter aliquots of plasma containing a tracer amount of [G-(3)H]paclitaxel with high-specific activity against an equal volume of 0.01 M phosphate buffer (pH 7.4). Drug concentrations were measured by both reversed-phase HPLC and liquid scintillation counting. Using this method, fu has been measured in three patients receiving three consecutive 3-weekly courses of paclitaxel at dose levels of 135, 175, and 225 mg/m(2) and found to range between 0.036 and 0.079. The method was also used to define concentration-time profiles of unbound drug, estimated from the product of the total plasma concentration and fu