WaveGate: a versatile tool for temporal shaping of synchrotron beams.

We present a full performance characterization of a solid state pulse picker for hard x-ray pulses at synchrotrons. The device is called WaveGate. Specifically, we quantify its efficiency (>30 %), timing capabilities (switching times between 100 ns and ms), on-off contrast (>104) and influence on the coherence properties of the incident x-ray beam. In addition, we discuss the implementation of the WaveGate in an optical pump - x-ray probe setup. Even if single pulse selection is performed by external detector gating, the WaveGate drastically increases the efficiency of a measurement. Finally, we introduce advanced timing schemes that can be realized by modulating the time structure of the synchrotron beam.

Bionics and green technology in maritime shipping: an assessment of the effect of Salvinia air-layer hull coatings for drag and fuel reduction.

To save energy and reduce environmental impacts, new technologies towards a development of a sustainable 'greener' economy are needed. The main opportunity to improve sustainability by reducing emissions is within the transport sector. More than 90% of all goods worldwide are transported by ships. Particularly maritime ships using heavy fuel oil and marine gas oil play a major role. The total fuel consumption of shipping in 2016 was about 250 m t (domestic ca. 50 m t, international shipping ca. 200 m t). The vast portion of the energy consumption of a ship is the need to overcome the drag between ship hull and water-depending on the shape of the vessel and its size up to 90% of total fuel consumption. This means reducing drag helps to save fuel and reduces carbon emissions as well as pollution considerably. Different techniques for drag reduction are known, e.g. the micro-bubble technique or the bulbous bow. We investigated a novel bioinspired technique since 2002: the application of biomimetic surfaces with long-term stable air layers on ship hulls, serving as a slip agent. This technology is based on the Salvinia Effect, allowing a permanent stabilization of air layers under water. In this case study, we analysed the possible savings, which also could be combined with modified micro-bubble technologies. We calculated, based on a selection of five ship types, representing 75% of the world fleet, that air-layer hull coatings could lead to estimated savings of 32.5 million tons of fuel (meaning 13.0% of the worldwide shipping fuel consumption), equal to 18.5 billion US$ and 130.0 million tons of CO2e per year. The positive impacts on global temperature and other greenhouse gases are calculated and could be a contributing factor in accomplishing the UN Sustainable Development Goals and the Paris Agreement to the UN Framework Convention on Climate Change. The study is a contribution to enhance our patchy knowledge concerning the potential economic and ecological benefit of bionics and biomimetic technologies. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.

Survival of lactic acid and propionibacteria in low- and full-fat Dutch-type cheese during human digestion ex vivo.

UNLABELLED: The survival of selected bacteria in semi-hard experimental cheeses was studied after exposure to human gastric and duodenal juices in an ex vivo model. Experimental cheeses (10 and 28% fat) were supplemented with different strains of Lactobacillus sp. and Propionibacterium sp. and ripened for 7 and 70 weeks. After digestion, greater numbers of the adjunct bacteria we rerecorded in the 7-week-old cheeses compared to the well-matured cheeses (70 weeks). The bacterial survival was strain dependent, and influenced by the fat content of the cheese. Lactobacilli showed better survival, especially when in low-fat cheeses. The strains of propionibacteria also survived well during the digestion of the low-fat cheeses. The results confirmed that cheese can potentially be a good carrier matrix for bacteria to the intestine. In addition, it has been shown that different strains present in cheese have different abilities to survive the conditions of the gastrointestinal tract. Younger cheese was indicated to be a better carrier, possibly because the bacteria present in those cheeses have had shorter exposure to the stress conditions occurring in cheese during prolonged maturation. SIGNIFICANCE AND IMPACT OF THE STUDY: Cheese can function as a suitable vehicle for the delivery of a variety of food-related micro-organisms to the intestine. Young cheese as well as low-fat cheeses are better carrier matrixes than full-fat and/or more well-ripened cheeses. Most of the lactobacilli and all the propionibacteria survived well during digestion of the low-fat cheeses. This study also showed the ability of cheese lactobacilli and PAB to survive the severe conditions of GIT.

Game theoretic treatments for the differentiation of functional roles in the transition to multicellularity.

Multicellular organisms are characterised by role specialisation, brought about by the epigenetic differentiation of their constituent parts. Conventional game theoretic studies of cooperation do not account for this division of labour, nor do they allow for the possibility of the plastic expression of phenotype. We address these issues by extending the notion of cooperative dilemmas to account for such interaction in which heterogeneous roles are advantageous and present an extended dynamical model of selection that allows for the possibility of conditional expression of phenotype. We use these models to investigate systematically when selection will favour an adaptive diversification of roles. We argue that such extensions to models and concepts are necessary to understand the origins of multicellularity and development.

Flow sensing by pinniped whiskers.

Beside their haptic function, vibrissae of harbour seals (Phocidae) and California sea lions (Otariidae) both represent highly sensitive hydrodynamic receptor systems, although their vibrissal hair shafts differ considerably in structure. To quantify the sensory performance of both hair types, isolated single whiskers were used to measure vortex shedding frequencies produced in the wake of a cylinder immersed in a rotational flow tank. These measurements revealed that both whisker types were able to detect the vortex shedding frequency but differed considerably with respect to the signal-to-noise ratio (SNR). While the signal detected by sea lion whiskers was substantially corrupted by noise, harbour seal whiskers showed a higher SNR with largely reduced noise. However, further analysis revealed that in sea lion whiskers, each noise signal contained a dominant frequency suggested to function as a characteristic carrier signal. While in harbour seal whiskers the unique surface structure explains its high sensitivity, this more or less steady fundamental frequency might represent the mechanism underlying hydrodynamic reception in the fast swimming sea lion by being modulated in response to hydrodynamic stimuli impinging on the hair.

Vascular hypertrophy and increased P70S6 kinase in mice lacking the angiotensin II AT(2) receptor.

BACKGROUND: Angiotensin II activates 2 distinct G protein-coupled receptors, the AT(1) and AT(2) receptors. Most of the known cardiovascular effects of angiotensin II are mediated by the AT(1) receptor subtype. The aim of the present study was to test whether deletion of the AT(2) receptor gene in mice (AT(2)-KO mice) leads to long-term functional or structural alterations in the cardiovascular system. METHODS AND RESULTS: In vivo pressure responses to angiotensin II or the alpha(1)-adrenergic receptor agonist phenylephrine were greatly enhanced in AT(2)-KO mice. Deletion of the angiotensin AT(2) receptor did not lead to a compensatory increase of the activity of the circulating renin-angiotensin system, and arterial blood pressure was identical in wild-type control mice (WT) and AT(2)-KO mice. Cardiac contractility as assessed by LV catheterization and by rapid MRI also did not differ between AT(2)-KO and WT mice. Isolated femoral arteries from AT(2)-KO mice, however, showed enhanced vasoconstriction to angiotensin II, norepinephrine, and K(+) depolarization compared with WT. Morphometric analysis of large and small femoral arteries revealed a significant hypertrophy of media smooth muscle cells. Phospho-P70S6 kinase levels were significantly increased in aortas from AT(2)-KO mice compared with WT mice. Treatment of mice with an ACE inhibitor for 8 weeks abolished the increased pressure responsiveness, vascular hypertrophy, and enhanced P70S6 kinase phosphorylation in AT(2)-KO mice. CONCLUSIONS: These results indicate that vascular AT(2) receptors inhibit the activity and, hence, hypertrophic signaling by the P70S6 kinase in vivo and thus are important regulators of vascular structure and function.

Differential distribution of beta-adrenergic receptor subtypes in blood vessels of knockout mice lacking beta(1)- or beta(2)-adrenergic receptors.

beta-Adrenergic receptors (beta-AR) are essential regulators of cardiovascular homeostasis. In addition to their prominent function in the heart, beta-AR are located on vascular smooth muscle cells, where they mediate vasodilating effects of endogenous catecholamines. In this study, we have investigated in an isometric myograph different types of blood vessels from mice lacking beta(1)- and/or beta(2)-adrenergic receptor subtypes (beta(1)-KO, beta(2)-KO, beta(1)beta(2)-KO). In wild-type mice, isoproterenol induced relaxation of segments from thoracic aorta, carotid, femoral and pulmonary arteries, and portal vein. The relaxant effect of beta-receptor stimulation was absent in femoral and pulmonary arteries from beta(1)-KO mice. In aortic and carotid arteries and in portal veins, the vasodilating effect of isoproterenol was reduced in mice lacking beta(1)- or beta(2)-receptors. However, in these vessels the vasodilating effect was only abolished in double KO mice lacking both beta(1)- and beta(2)-receptors. Vessel relaxation induced by forskolin did not differ between wild-type and KO mice. Similar contributions of beta(1)- and beta(2)-receptors to isoproterenol-induced vasorelaxation were found when vessels from KO mice were compared with wild-type arteries in the presence of subtype-selective beta-receptor antagonists. These studies demonstrate that beta(1)-adrenergic receptors play a dominant role in the murine vascular system to mediate vasodilation. Surprisingly, beta(2)-receptors contribute to adrenergic vasodilation only in a few major blood vessels, suggesting that differential distribution of beta-adrenergic receptor subtypes may play an important role in redirection of tissue perfusion.

Architecture of idiotypic networks: percolation and scaling behavior.

We investigate a model where idiotypes (characterizing B lymphocytes and antibodies of an immune system) and anti-idiotypes are represented by complementary bit strings of a given length d allowing for a number of mismatches (matching rules). In this model, the vertices of the hypercube in dimension d represent the potential repertoire of idiotypes. A random set of (with probability p) occupied vertices corresponds to the expressed repertoire of idiotypes at a given moment. Vertices of this set linked by the above matching rules build random clusters. We give a structural and statistical characterization of these clusters, or in other words of the architecture of the idiotypic network. Increasing the probability p one finds at a critical p a percolation transition where for the first time a large connected graph occurs with probability 1. Increasing p further, there is a second transition above which the repertoire is complete in the sense that any newly introduced idiotype finds a complementary anti-idiotype. We introduce structural characteristics such as the mass distribution and the fragmentation rate for random clusters, and determine the scaling behavior of the cluster size distribution near the percolation transition, including finite size corrections. We find that slightly above the percolation transition the large connected cluster (the central part of the idiotypic network) consists typically of one highly connected part and a number of weakly connected constituents and coexists with a number of small, isolated clusters. This is in accordance with the picture of a central and a peripheral part of the idiotypic network and gives some support to idealized architectures of the central part used in recent dynamical mean field models.

Transgenic mouse models of angiotensin receptor subtype function in the cardiovascular system.

Angiotensin II mediates is biological actions via different subtypes of G protein-coupled receptors, termed AT(1) and AT(2) receptors. In rodents, two AT(1) receptors have been identified, AT(1A) and AT(1B), whereas in humans a single AT(1) receptor exists. Recently, a number of transgenic animal models have been generated which overexpress or lack functional angiotensin II receptor subtypes. This review focuses on the physiological significance of angiotensin II receptor subtype diversity in the cardiovascular system. In the mouse, AT(1A) receptors are the major regulators of cardiovascular homeostasis by determining vascular tone and natriuresis. In addition, AT(1A) receptors mediate growth-stimulating signals in vascular and cardiac myocytes. AT(1B) receptors participate in blood pressure regulation, and their functions become apparent when the AT(1A) receptor gene is deleted. Deletion of the mouse gene for the AT(2) receptor subtype led to hypersensitivity to pressor and antinatriuretic effects of angiotensin II in vivo, suggesting that the AT(2) receptor subtype counteracts some of the biological effects of AT(1) receptor signalling.

Influence of therapeutic phenobarbital and phenytoin medication on the polygraphic sleep of patients with epilepsy.

Sleep is a modulator of seizure activity, and many antiepileptic drugs are modulators of sleep. Can influences on sleep organization be involved in antiepileptic drug action, and can these partly account for differences in drug response of various epileptic syndromes? Much more exact data must be collected before these questions can be adequately discussed. The polygraphic sleep of 40 unmedicated epileptic patients was recorded and compared with polygraphy after adjustment to therapeutic steady states of phenobarbital (PB) and phenytoin (DPH) (as sequential sole agents in a crossover design with random sequence). With PB, patients fell asleep more rapidly and had fewer movements, movement arousals, and arousal awakenings, all of which could be beneficial, especially for patients with generalized epilepsy. Light sleep was increased, and REM sleep decreased. The usual sleep pattern was altered, with maximal deep sleep early and maximal REM sleep late in the night. PB seemed to have maximal effect in the first REM cycle. With DPH, sleep onset also came sooner, but light sleep was decreased and deep sleep increased, with no alteration of REM sleep. In contrast to PB, the changes in sleep organization were toward leveling the distribution of deep NREM sleep. The maximal alterations were observed in the third REM cycle. With both drugs, there were some differences in the response of generalized as opposed to focal epilepsies, and of awakening as opposed to sleep epilepsies. Thus, the early REM cycles seemed to be more modifiable by drugs in patients with generalized or awakening epilepsies than in patients with focal or sleep epilepsies.(ABSTRACT TRUNCATED AT 250 WORDS)