Sub-ballistic behavior in quantum systems with L\'evy noise

We investigate the quantum walk and the quantum kicked rotor in resonance subjected to noise with a L\'evy waiting time distribution. We find that both systems have a sub-ballistic wave function spreading as shown by a power-law tail of the standard deviation.Comment: 4 pages, 4 figure

Significant enhancement of irreversibility field in clean-limit bulk MgB2

Low resistivity ("clean") MgB2 bulk samples annealed in Mg vapor show an increase in upper critical field Hc2(T) and irreversibility field Hirr(T) by a factor of 2 in both transport and magnetic measurements. The best sample displayed Hirr above 14 T at 4.2 K and 6 T at 20 K. These changes were accompanied by an increase of the 40 K resistivity from 1.0 to 18 microohm-cm and a lowering of the resistivity ratio from 15 to 3, while the critical temperature Tc decreased by only 1-2 K. These results point the way to make prepare MgB2 attractive for magnet applications.Comment: 3 pages, 4 figures, submitted to Applied Physics Letter

Critical Field of MGB2 : Crossover from Clean to Dirty Regimes

We have studied the upper critical field, Bc2, in poly-crystalline MgB2 samples in which disorder was varied in a controlled way to carry selectively p and s bands from clean to dirty limit. We have found that the clean regime survives when p bands are dirty and s bands are midway between clean and dirty. In this framework we can explain the anomalous behaviour of Al doped samples, in which Bc2 decreases as doping increases.Comment: 11 pages, 2 figure

Aircraft/island/ship/satellite intercomparison: Preliminary results from July 16, 1987

The First ISCCP Regional Experiment (FIRE) objective of validating and improving satellite algorithms for inferring cloud properties from satellite radiances was one of the central motivating factors in the design of the specific field experimental strategies used in the July, 1987 marine stratocumulus intensive field observations (IFO). The in situ measuring platforms were deployed to take maximum advantage of redundant measurements (for intercomparison of the in situ sensors) and to provide optimal coverage within satellite images. One of the most ambitious of these strategies was the attempt to coordinate measurements from San Nicolas Island (SNI), the R/V Pt. Sur, the meteorological aircraft, and the satellites. For the most part, this attempt was frustrated by flight restrictions in the vicinity of SNI. The exception was the mission of July 16, 1987, which achieved remarkable success in the coordination of the platforms. This presentation concerns operations conducted by the National Center for Atmospheric Research (NCAR) Electra and how data from the Electra can be integrated with and compared to data from the Pt. Sur, SNI, and the satellites. The focus is on the large-scale, integrated picture of the conditions on July 16 from the perspective of the Electra's flight operations

As safe as houses? Why standards for urban development matter

Standards for designing, improving, and maintaining the built environment have conceptual and practical value for health. Yet, their importance runs the risk of being subsumed in tangential discourses, including over their applicability for particular populations or in particular contexts. This paper applies an integrative systems perspective to several relevant scenarios, while broadly revisiting the health rationale for built environment standards. As with any intervention, standards can have negative unintended consequences, in some cases inducing adverse outcomes. Yet, forgoing standards is not an acceptable answer for sustainable urbanization. The systems perspective adopted here surveys some of the driving forces that underlie adverse outcomes, and suggests potential leverage points and criteria for action

What's in a word? Conflicting interpretations of vulnerability in climate change research

In this paper, we discuss two competing interpretations of vulnerability in the climate change literature and consider the implications for both research and policy. The first interpretation, which can be referred to as the “end point” approach, views vulnerability as a residual of climate change impacts minus adaptation. The second interpretation, which takes vulnerability as a “starting point,” views vulnerability as a general characteristic generated by multiple factors and processes. Viewing vulnerability as an end point considers that adaptations and adaptive capacity determine vulnerability, whereas viewing vulnerability as a starting point holds that vulnerability determines adaptive capacity. The practical consequences of these two interpretations are illustrated through the examples of Norway and Mozambique. We show that, if the underlying causes and contexts of vulnerability are not taken into account, there is a danger of underestimating the magnitude (large), scope (social and environmental) and urgency (high) of climate change

Male and female entrepreneurs’ employment growth ambitions: the contingent role of regulatory efficiency

Entrepreneurs start and grow their ventures in a widely varying set of institutional contexts. One differentiator is a country’s regulatory efficiency which encompasses the freedom to start and to run a business without excessive government interventions around registering, hiring, and firing employees, and price controls on currency. The efficiency of regulations varies substantially among countries and imposes additional costs and risks on entrepreneurs’ activities. We integrate insights from institutional theory and recent literature on gender and entrepreneurship to better understand how a country’s regulatory efficiency affects male and female entrepreneurs’ employment growth ambitions. We explore three aspects of regulatory efficiency: business freedom (e.g., to start, operate, and close a venture), labor freedom (e.g., laws around minimum wage, layoffs, severance), and monetary freedom (e.g., price stability) using data from over 47,000 entrepreneurs in 68 countries. We find that entrepreneurs’ growth ambitions are higher in countries with more efficient regulations, particularly those countries characterized by fewer labor law restrictions and greater monetary freedoms. These findings are further exacerbated by gender by such that, relative to their female counterparts, male entrepreneurs have significantly greater venture growth ambitions. Our paper contributes to the discussion on how formal institutions influence women and men entrepreneurs in distinct ways

Enhanced flux pinning in neutron irradiated MgB2

We study the effect of neutron irradiation on the critical current density Jc of isotopically pure polycrystalline Mg11B2 samples. For fluences in the range 1017-1018 cm-2, Jc is enhanced and its dependence on magnetic field is significantly improved: we demonstrate that, in this regime, point-like pinning centers are effectively introduced in the system proportionally to the neutron fluence. Instead, for larger fluences, a strong suppression of the critical temperature accompanied by a decrease of both the upper critical field Bc2 and Jc is found.Comment: 13 pages, 3 igure

Governance, Institutions and People within the Interface of a Tsunami Early Warning System

The interface mechanism in a tsunami early warning system (TEWS) occurs between receiving tsunami information at the country level and disseminating warning and evacuation orders to the public. Three crucial actions take place during the interface: issuing the warning, disseminating it, and ordering an evacuation. Using two case studies in Indonesia and Sri Lanka, a study was undertaken to understand the nature of the interface mechanism and the social, cultural and political dynamics of its operationalisation. In this article, a comparative analysis of the two case studies is presented, focusing on the role of governance, institutions and people in this interface. The nature of governance, hierarchies and structures influence the interface mechanism and the associated decision-making mechanisms. The institutions who act as key stakeholders are also shaped by the governance structures and hierarchies within it. The efficiency of the institutions is determined by the nature of their human resources and are affected by political factors. The communities are also affected by the overall governance structure, the political dynamics and the institutional factors. The complex relationships between governance, institutions and officers that exist in the two countries affect the communities in different ways. Yet, the overall governance and institutional dynamics of TEWSs lead to a common thread of decisions and actions when operationalising the interface. The results are presented in a framework that illustrates the complex relationships between governance, institutions, officers and communities. The framework provides a basis for future research on how the interface of TEWS can be operationalised to effectively protect communities at risk from tsunami

High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines †

International audienceThe (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (K a ∼ 2 × 10 5 M −1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ∼10 3) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its " long molecular axis " inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular para-magnetic rotor with increased rotational speed of the rotator that has great potential for advanced nano-scale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars)