Adaptive Optics for Astronomy

Adaptive Optics is a prime example of how progress in observational astronomy can be driven by technological developments. At many observatories it is now considered to be part of a standard instrumentation suite, enabling ground-based telescopes to reach the diffraction limit and thus providing spatial resolution superior to that achievable from space with current or planned satellites. In this review we consider adaptive optics from the astrophysical perspective. We show that adaptive optics has led to important advances in our understanding of a multitude of astrophysical processes, and describe how the requirements from science applications are now driving the development of the next generation of novel adaptive optics techniques.Comment: to appear in ARA&A vol 50, 201

Number partitioning as random energy model

Number partitioning is a classical problem from combinatorial optimisation. In physical terms it corresponds to a long range anti-ferromagnetic Ising spin glass. It has been rigorously proven that the low lying energies of number partitioning behave like uncorrelated random variables. We claim that neighbouring energy levels are uncorrelated almost everywhere on the energy axis, and that energetically adjacent configurations are uncorrelated, too. Apparently there is no relation between geometry (configuration) and energy that could be exploited by an optimization algorithm. This ``local random energy'' picture of number partitioning is corroborated by numerical simulations and heuristic arguments.Comment: 8+2 pages, 9 figures, PDF onl

Evolutionarily conserved regulation of hypocretin neuron specification by Lhx9

Loss of neurons that express the neuropeptide hypocretin (Hcrt) has been implicated in narcolepsy, a debilitating disorder characterized by excessive daytime sleepiness and cataplexy. Cell replacement therapy, using Hcrt-expressing neurons generated in vitro, is a potentially useful therapeutic approach, but factors sufficient to specify Hcrt neurons are unknown. Using zebrafish as a high-throughput system to screen for factors that can specify Hcrt neurons in vivo, we identified the LIM homeobox transcription factor Lhx9 as necessary and sufficient to specify Hcrt neurons. We found that Lhx9 can directly induce hcrt expression and we identified two potential Lhx9 binding sites in the zebrafish hcrt promoter. Akin to its function in zebrafish, we found that Lhx9 is sufficient to specify Hcrt-expressing neurons in the developing mouse hypothalamus. Our results elucidate an evolutionarily conserved role for Lhx9 in Hcrt neuron specification that improves our understanding of Hcrt neuron development

UV radiation enhanced oxygen vacancy formation caused by the PLD plasma plume

Pulsed Laser Deposition is a commonly used non-equilibrium physical deposition technique for the growth of complex oxide thin films. A wide range of parameters is known to influence the properties of the used samples and thin films, especially the oxygen-vacancy concentration. One parameter has up to this point been neglected due to the challenges of separating its influence from the influence of the impinging species during growth: the UV-radiation of the plasma plume. We here present experiments enabled by a specially designed holder to allow a separation of these two influences. The influence of the UV-irradiation during pulsed laser deposition on the formation of oxygen-vacancies is investigated for the perovskite model material SrTiO3. The carrier concentration of UV-irradiated samples is nearly constant with depth and time. By contrast samples not exposed to the radiation of the plume show a depth dependence and a decrease in concentration over time. We reveal an increase in Ti-vacancy–oxygen-vacancy-complexes for UV irradiated samples, consistent with the different carrier concentrations. We find a UV enhanced oxygen-vacancy incorporation rate as responsible mechanism. We provide a complete picture of another influence parameter to be considered during pulsed laser depositions and unravel the mechanism behind persistent-photo-conductivity in SrTiO3

Teams between Neo-Taylorism and Anti-Taylorism

The concept of teamworking is the product of two distinct developments. One: a neo- Tayloristic form of organization of work, of which Toyota has shown that it can be very profitable, was packaged and reframed to make it acceptable to the Western public. Two: anti-Tayloristic ways of organizing work, inspired by ideals of organizational democracy, were relabeled to make these acceptable to profit-oriented managers. Drawing on empirical research in Scandinavia, Germany, The Netherlands and the UK, as well as on published case studies of Japanese companies, the paper develops a neo-Tayloristic and an anti-Tayloristic model of teamworking. Key concerns in the teamworking literature are intensification of work and the use of shop floor autonomy as a cosmetic or manipulative device. Indeed, all the features of neo-Tayloristic teamworking are geared towards the intensification of work. However, one of the intensification mechanisms, the removal of Tayloristic rigidities in the division of labor, applies to anti-Tayloristic teamworking as well. This poses a dilemma for employee representatives. In terms of autonomy, on the other hand, the difference between neo-Tayloristic and anti-Tayloristic teamworking is real. In anti-Tayloristic teamworking, there is no supervisor inside the team. The function of spokesperson rotates. All team members can participate in decision-making. Standardization is not relentlessly pursued; management accepts some measure of worker control. There is a tendency to alleviate technical discipline, e.g. to find alternatives for the assembly line. Buffers are used. Remuneration is based on proven skill level; there are no group bonuses. In contrast, in neo-Tayloristic teamworking, a permanent supervisor is present in the team as team leader. At most, only the team leader can participate in decision-making. Standardization is relentlessly pursued. Management prerogatives are nearly unlimited. Job designers treat technical discipline, e.g. short-cycled work on the assembly line, as unproblematic. There are no buffers. A substantial part of wages consists of individual bonuses based on assessments by supervisors on how deeply workers cooperate in the system. Group bonuses are also given. The instability and vulnerability of anti-Tayloristic teamworking imply that it can only develop and flourish when managers and employee representatives put determined effort into it. The opportunity structure for this contains both economic and political elements. In mass production, the economic success of Toyota, through skillful mediation by management gurus, makes the opportunity structure for anti-Tayloristic teamworking relatively unfavorable

The Ctf18 RFC-like complex positions yeast telomeres but does not specify their replication time

Peer reviewedPreprin

Legislative History: An Act Concerning the Operation of Emergency Medical Vehicles (SP482)(LD 1303)

https://digitalmaine.com/legishist114/2302/thumbnail.jp

Authenticating the Query Results of Text Search Engines

The number of successful attacks on the Internet shows that it is very difficult to guarantee the security of online search engines. A breached server that is not detected in time may return incorrect results to the users. To prevent that, we introduce a methodology for generating an integrity proof for each search result. Our solution is targeted at search engines that perform similarity-based document retrieval, and utilize an inverted list implementation (as most search engines do). We formulate the properties that define a correct result, map the task of processing a text search query to adaptations of existing threshold-based algorithms, and devise an authentication scheme for checking the validity of a result. Finally, we confirm the efficiency and practicality of our solution through an empirical evaluation with real documents and benchmark queries. 1