Mode hopping strongly affects observability of dynamical instability in optical parametric oscillators

Theoretical investigations of dynamical behavior in optical parametric oscillators (OPO) have generally assumed that the cavity detunings of the interacting fields are controllable parameters. However, OPOs are known to experience mode hops, where the system jumps to the mode of lowest cavity detuning. We note that this phenomenon significantly limits the range of accessible detunings and thus may prevent instabilities predicted to occur above a minimum detuning from being evidenced experimentally. As a simple example among a number of instability mechanisms possibly affected by this limitation, we discuss the Hopf bifurcation leading to periodic behavior in the monomode mean-field model of a triply resonant OPO and show that it probably can be observed only in very specific setups.Comment: submitted to Phys. Rev.

Spatial repartition of local plastic processes in different creep regimes in a granular material

Granular packings under constant shear stress display below the Coulomb limit, a logarithmic creep dynamics. However the addition of small stress modulations induces a linear creep regime characterized by an effective viscous response. Using Diffusing Wave Spectroscopy, we investigate the relation between creep and local plastic events spatial distribution ("hot-spots") contributing to the plastic yield. The study is done in the two regimes, i.e. with and without mechanical activation. The hot-spot dynamics is related to the material effective fluidity. We show that far from the threshold, a local visco-elastic rheology coupled to an ageing of the fluidity parameter, is able to render the essential spatio-temporal features of the observed creep dynamics

Organometallic Ruthenium Complexes of Novel Thiosemicarbazones

We present the preliminary results of a study of two novel thiosemicarbazones (TSCs) and theirruthenium complexes. The TSCs were prepared by refluxing thiosemicarbazide with 9-anthraldehyde or benzanthrone in ethanol for 3 hours. The metal complex of each ligand (complex I =[(r|6 -C6H6 )Ru(9-ant-TSC )(C1)]C1 and complex II= [(r|6 -C6H6 )Ru(benz-TSC)(Cl)]Cl) was prepared by refluxing the appropriate TSC with [(r|6 -C6H6 )RuCl 2 ] r The compounds were characterized using infrared, ultraviolet-visible, and NMRspectroscopy. Two different methods, the disk diffusion test and luminometry, were used to test the compounds against a variety of different bacterial strains for antibacterial activity. The most optimistic results were obtained for the 9-ant-TSC ligand, especially in relation to activity against Gram (+) bacteria. The metal complexes showed no measurable activity and further biological testing of the metal complexes is currently being conducted

Mitotic entry in the presence of DNA damage is a widespread property of aneuploidy in yeast

Genetic instability is a hallmark of aneuploidy in budding and fission yeast. All aneuploid yeast strains analyzed to date harbor elevated levels of Rad52-GFP foci, a sign of DNA damage. Here we investigate how continuously elevated levels of DNA damage affect aneuploid cells. We show that Rad52-GFP foci form during S phase, consistent with the observation that DNA replication initiation and elongation are impaired in some aneuploid yeast strains. We furthermore find that although DNA damage is low in aneuploid cells, it nevertheless has dramatic consequences. Many aneuploid yeast strains adapt to DNA damage and undergo mitosis despite the presence of unrepaired DNA leading to cell death. Wild-type cells exposed to low levels of DNA damage exhibit a similar phenotype, indicating that adaptation to low levels of unrepaired DNA is a general property of the cell's response to DNA damage. Our results indicate that by causing low levels of DNA damage, whole-chromosome aneuploidies lead to DNA breaks that persist into mitosis. Such breaks provide the substrate for translocations and deletions that are a hallmark of cancer

Single cell sequencing reveals low levels of aneuploidy across mammalian tissues

Whole-chromosome copy number alterations, also known as aneuploidy, are associated with adverse consequences in most cells and organisms. However, high frequencies of aneuploidy have been reported to occur naturally in the mammalian liver and brain, fueling speculation that aneuploidy provides a selective advantage in these organs. To explore this paradox, we used single cell sequencing to obtain a genome-wide, high-resolution assessment of chromosome copy number alterations in mouse and human tissues. We find that aneuploidy occurs much less frequently in the liver and brain than previously reported and is no more prevalent in these tissues than in skin. Our results highlight the rarity of chromosome copy number alterations across mammalian tissues and argue against a positive role for aneuploidy in organ function. Cancer is therefore the only known example, in mammals, of altering karyotype for functional adaptation.National Institutes of Health (U.S.). Physical Sciences Oncology Center (Grant 5-U54-CA143874)Ellison Medical Foundation (Senior Scholar Award)National Cancer Institute (U.S.) (Koch Institute. Grant P30-CA14051)Howard Hughes Medical InstituteKathy and Curt Marble Cancer Research Fun

Anaerobic digestion of whole-crop winter wheat silage for renewable energy production

With biogas production expanding across Europe in response to renewable energy incentives, a wider variety of crops need to be considered as feedstock. Maize, the most commonly used crop at present, is not ideal in cooler, wetter regions, where higher energy yields per hectare might be achieved with other cereals. Winter wheat is a possible candidate because, under these conditions, it has a good biomass yield, can be ensiled, and can be used as a whole crop material. The results showed that, when harvested at the medium milk stage, the specific methane yield was 0.32 m3 CH4 kg–1 volatile solids added, equal to 73% of the measured calorific value. Using crop yield values for the north of England, a net energy yield of 146–155 GJ ha–1 year–1 could be achieved after taking into account both direct and indirect energy consumption in cultivation, processing through anaerobic digestion, and spreading digestate back to the land. The process showed some limitations, however: the relatively low density of the substrate made it difficult to mix the digester, and there was a buildup of soluble chemical oxygen demand, which represented a loss in methane potential and may also have led to biofoaming. The high nitrogen content of the wheat initially caused problems, but these could be overcome by acclimatization. A combination of these factors is likely to limit the loading that can be applied to the digester when using winter wheat as a substrat

Multimedia delivery in the future internet

The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio and video are produced, distributed, shared, managed and consumed on-line through various networks, like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked challenges of the Networked Media in the transition to the Future of the Internet. Internet has evolved and changed the way we work and live. End users of the Internet have been confronted with a bewildering range of media, services and applications and of technological innovations concerning media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged that in a near- to mid-term future, the Internet will provide the means to share and distribute (new) multimedia content and services with superior quality and striking flexibility, in a trusted and personalized way, improving citizens’ quality of life, working conditions, edutainment and safety. In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and innovative applications “on the move”, like virtual collaboration environments, personalised services/ media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to contribute towards such a vision. Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6) and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way ahead in the area of Content Aware media delivery platforms

New Frontiers of Quantified Self 3: Exploring Understudied Categories of Users

Quantified Self (QS) field needs to start thinking of how situated needs may affect the use of self-tracking technologies. In this workshop we will focus on the idiosyncrasies of specific categories of users