3,256 research outputs found

    Time-optimal control fields for quantum systems with multiple avoided crossings

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    We study time-optimal protocols for controlling quantum systems which show several avoided level crossings in their energy spectrum. The structure of the spectrum allows us to generate a robust guess which is time-optimal at each crossing. We correct the field applying optimal control techniques in order to find the minimal evolution or quantum speed limit (QSL) time. We investigate its dependence as a function of the system parameters and show that it gets proportionally smaller to the well-known two-level case as the dimension of the system increases. Working at the QSL, we study the control fields derived from the optimization procedure, and show that they present a very simple shape, which can be described by a few parameters. Based on this result, we propose a simple expression for the control field, and show that the full time-evolution of the control problem can be analytically solved.Comment: 11 pages, 7 figure

    Geosites and geological landscape map of Liguria (Italy)

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    Since the beginning of the Third Millennium, an ever-increasing interest of geoheritage has been observed, either in scientific terms or in practical point of view, with the resulting socio-economic consequences. Geoheritage represents the basic element of the landscape and it often has strong links with other elements of the territory like historical geography, land-use setting, landscape protection, nature conservation, etc. Oneimportant link is tied to the environmental protection task, because most part of the Italian protected areas are mainly established above Earth Sciences features. Consequently, a lot of geosite sare included into these important natural sites. The issue of geoheritage and geosites has become object of national and regional laws: in Italy the cultural heritage and landscape code was issued in 2004 while in Liguria the Regional Law n. 39/2009 establishes the rules for the valorisation of the geodiversity, geosites and karst areas. Here we present an overview of geosites and geological landscape of Liguria (North West Italy); in addition to the recent regional database and georeferencing activities of the Ligurian geosites, through a reworking of a simplified geological map addressed also for non-geologists, a geotematic map has been defined. In particular, this product emphasizes the relationship between geology and landscape, showing how different rock masses produce several landforms of outstanding natural beauty in the ligurian territory. The map shows the basic concepts of geoscience by looking closely at the landscape we see in front of us every day. From the coast to the Alps and Apennines watershed, we identified several geological landscape units characterized by specific rock masses, soils and particular geological and geomorphological features, such as: 1) Palaeolandslides landscape; 2) Ligurian alluvial floodplains; 3)Ligurian coastal plains; 4) the Flysch rock masses; 5) Ophiolitic crags; 6) Conglomerate peaks; 7) Karstic massif; 8) Quartzite and Cherts rock masses; 9) Sandstone spurs; 10) Shales and schists domain; 11) Windows on the Paleozoic; 12) Plio- Quaternary landscape. More than 500 geosites classified in a recent specific regional database were then overlapped on the geological landscape units: they have been distinguished according to interest, for different geothematic categories, according to the proposal of enhancement. The Ligurian geosites and geological landscape overview map could represents a friendly tool to identify the most relevant regional geological heritage

    Maximum population transfer in a periodically driven two-level system

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    We study the dynamics of a two-level quantum system under the influence of sinusoidal driving in the intermediate frequency regime. Analyzing the Floquet quasienergy spectrum, we find combinations of the field parameters for which population transfer is optimal and takes place through a series of well defined steps of fixed duration. We also show how the corresponding evolution operator can be approximated at all times by a very simple analytical expression. We propose this model as being specially suitable for treating periodic driving at avoided crossings found in complex multi-level systems, and thus show a relevant application of our results to designing a control protocol in a realistic molecular modelComment: 7 pages, 6 figure

    Finding a reflexive voice : -- researching the problems of implementing new learning practices within a New Zealand manufacturing organisation : a 100pt thesis presented in partial fulfilment of the requirements for the degree of Master of Management in Human Resources Management at Massey University

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    This study explored the social forces mediating manager's participation in a new reflexive participative learning practice designed to improve profitability within a New Zealand manufacturing organisation. Despite a large theoretical and managerial body of literature on organisational learning there has been little empirical investigation of how people experience and engage their reflexivity towards challenging the status-quo to create high level learning and new knowledge. Power was identified as a potential moderator of the reflexive learning experience and the variable relations of power and learning were constructed from a review of literature and these relationships were explored and investigated within the case study. Two prevailing discourses were identified as powerful moderators of public reflexivity, the traditionalist discourse which constructed managers actions and conversations towards insularism and survivalist concerns and the productionist discourse in which institutionalised production practices encircled and mediated managers actions and what constituted legitimacy in conversations. This study used a critical action research method to place the reflexive experience of managers and the researcher at the centre of the study and provide data representative of the social discourses that constructed variable freedoms and constraints upon the reflexive voice

    Characterizing dynamics with covariant Lyapunov vectors

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    A general method to determine covariant Lyapunov vectors in both discrete- and continuous-time dynamical systems is introduced. This allows to address fundamental questions such as the degree of hyperbolicity, which can be quantified in terms of the transversality of these intrinsic vectors. For spatially extended systems, the covariant Lyapunov vectors have localization properties and spatial Fourier spectra qualitatively different from those composing the orthonormalized basis obtained in the standard procedure used to calculate the Lyapunov exponents.Comment: 4 pages, 3 figures, submitted to Physical Review letter

    The state of SQL-on-Hadoop in the cloud

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    Managed Hadoop in the cloud, especially SQL-on-Hadoop, has been gaining attention recently. On Platform-as-a-Service (PaaS), analytical services like Hive and Spark come preconfigured for general-purpose and ready to use. Thus, giving companies a quick entry and on-demand deployment of ready SQL-like solutions for their big data needs. This study evaluates cloud services from an end-user perspective, comparing providers including: Microsoft Azure, Amazon Web Services, Google Cloud, and Rackspace. The study focuses on performance, readiness, scalability, and cost-effectiveness of the different solutions at entry/test level clusters sizes. Results are based on over 15,000 Hive queries derived from the industry standard TPC-H benchmark. The study is framed within the ALOJA research project, which features an open source benchmarking and analysis platform that has been recently extended to support SQL-on-Hadoop engines. The ALOJA Project aims to lower the total cost of ownership (TCO) of big data deployments and study their performance characteristics for optimization. The study benchmarks cloud providers across a diverse range instance types, and uses input data scales from 1GB to 1TB, in order to survey the popular entry-level PaaS SQL-on-Hadoop solutions, thereby establishing a common results-base upon which subsequent research can be carried out by the project. Initial results already show the main performance trends to both hardware and software configuration, pricing, similarities and architectural differences of the evaluated PaaS solutions. Whereas some providers focus on decoupling storage and computing resources while offering network-based elastic storage, others choose to keep the local processing model from Hadoop for high performance, but reducing flexibility. Results also show the importance of application-level tuning and how keeping up-to-date hardware and software stacks can influence performance even more than replicating the on-premises model in the cloud.This work is partially supported by the Microsoft Azure for Research program, the European Research Council (ERC) under the EUs Horizon 2020 programme (GA 639595), the Spanish Ministry of Education (TIN2015-65316-P), and the Generalitat de Catalunya (2014-SGR-1051).Peer ReviewedPostprint (author's final draft

    War and dissociation : the case of futurist aesthetics

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    Thanks to their deliberate engagement in state propaganda Italian Futurists deserved a prominent spot in the history of military aesthetics in the 20th century. However, under what looked like an unequivocal expression of support for war, lied a deep philosophical disagreement concerning its existential and epistemological value. The bone of contention concerned the effects of warfare on perception and, consequently, the means of its depiction. The author analyses this intellectual disagreement within the group and focuses, in particular, on its philosophical implications

    Attachment Styles and Communication of Displeasing Truths

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    This work explores how humans manage the communication of a displeasing and face-threatening truth and how the communicative strategies of the sender and the reaction of the receiver are influenced by their attachment style. Two experimental studies demonstrate that the attachment styles of both senders and receivers can influence the communicative styles of the sender, the emotions that both senders and receivers feel or attribute to their interlocutor, and the reactions of the receivers. In Study 1, couples of participants played a bogus computer game, ostensibly to test their abilities. Subsequently, “the spokesperson” was given the task to communicate to the “the receiver” a bogus low score of the other and a high score of oneself. Finally, all participants completed an adult Attachment Style Questionnaire (ASQ). A content analysis of the verbal messages of the spokespersons showed two main communication styles: frankness and mitigation. The results suggest that the spokespersons’ attachment style influences these communication styles. Using a similar procedure, Study 2 showed that spokespersons with a high avoidant attachment more frequently used frankness when communicating low scores to the receivers. Furthermore, the emotions and impressions reported by anxious and avoidant spokespersons and receivers, respectively, confirm the negative model of the self or the other, typical, respectively, in anxious and avoidant attachment. The detection of communicative strategies stemming from different attachment styles might be of use in user modeling and the planning of personalized systems
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