362 research outputs found
Antibunched photons emitted by a dc-biased Josephson junction
We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^7 photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain
Generating Mesoscopic Bell States via Collisions of Distinguishable Quantum Bright Solitons
We investigate numerically the collisions of two distinguishable quantum matter-wave bright solitons in a one-dimensional harmonic trap. We show that such collisions can be used to generate mesoscopic Bell states that can reliably be distinguished from statistical mixtures. Calculation of the relevant s-wave scattering lengths predicts that such states could potentially be realized in quantum-degenerate mixtures of Rb85 and Cs133. In addition to fully quantum simulations for two distinguishable two-particle solitons, we use a mean-field description supplemented by a stochastic treatment of quantum fluctuations in the soliton’s center of mass: we demonstrate the validity of this approach by comparison to a mathematically rigorous effective potential treatment of the quantum many-particle problem
From Social Network (Centralized vs. Decentralized) to Collective Decision-Making (Unshared vs. Shared Consensus)
Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many phenomena from amoebae to primates, we still do not know how consensus emerges from the properties of social networks in many biological systems. We created artificial social networks that represent the continuum from centralized to decentralized organization and used an agent-based model to make predictions about the patterns of consensus and collective movements we observed according to the social network. These theoretical results showed that different social networks and especially contrasted ones – star network vs. equal network - led to totally different patterns. Our model showed that, by moving from a centralized network to a decentralized one, the central individual seemed to lose its leadership in the collective movement's decisions. We, therefore, showed a link between the type of social network and the resulting consensus. By comparing our theoretical data with data on five groups of primates, we confirmed that this relationship between social network and consensus also appears to exist in animal societies
Lumped Element Kinetic Inductance Detectors for space applications
Kinetic Inductance Detectors (KID) are now routinely used in ground-based
telescopes. Large arrays, deployed in formats up to kilopixels, exhibit
state-of-the-art performance at millimeter (e.g. 120-300 GHz, NIKA and NIKA2 on
the IRAM 30-meters) and sub-millimeter (e.g. 350-850 GHz AMKID on APEX)
wavelengths. In view of future utilizations above the atmosphere, we have
studied in detail the interaction of ionizing particles with LEKID (Lumped
Element KID) arrays. We have constructed a dedicated cryogenic setup that
allows to reproduce the typical observing conditions of a space-borne
observatory. We will report the details and conclusions from a number of
measurements. We give a brief description of our short term project, consisting
in flying LEKID on a stratospheric balloon named B-SIDE.Comment: To appear in the SPIE 2016 Proceeding
Generation of energy selective excitations in quantum Hall edge states
We operate an on-demand source of single electrons in high perpendicular
magnetic fields up to 30T, corresponding to a filling factor below 1/3. The
device extracts and emits single charges at a tunable energy from and to a
two-dimensional electron gas, brought into well defined integer and fractional
quantum Hall (QH) states. It can therefore be used for sensitive electrical
transport studies, e.g. of excitations and relaxation processes in QH edge
states
Malaria control – two years' use of insecticide treated bednets compared with insecticide house spraying in Kwazulu-Natal
Objectives_ The objective of this study was to produce data indicating whether insecticide-treated bednets should replac insecticide house spraying as a malaria control method in South Africa_ We report 2 years of preliminary data on malaria incidence comparing areas receiving insecticidetreated bednets and those subjected to house spraying in northern KwaZulu-Natal.Design, setting and subjects. In order to measure significant reductions in malaria incidence between the two interventions, a geographical information system (GIS) was used to identify and create seven pairs of geographical blood ; (areas) in the malaria high-risk areas of Ndumu and Makani in Ingwavuma magisterial district, KwaZulu-Natal, Individual blocks were then randomly allocated to either insecticide-treated bednets or house spraying with deltamethrin. Malaria cases were either routinely recorded by surveillance agents at home or were reported to the nearest health facility_Results and conclusions. The results show that 2 years' use of insecticide-treated bednets by communities in Ndumu and Makanis, KwaZulu-Natal, significantly reduced the malaria incidence both in 1997 (rate ratio (RR) =0_879, 95% confidence interval (Cn 0.80 - 0.95, P =0.04) and in 1998 (RR = 0.667, Cl 0_61 - 0.72, P = 0.0001). Using a t-test, these significant reductions were further confirmed by an assessment of the rate of change between 1996 and 1998, showing a 16% reduction in malaria incidence in blocks using bednets and an increase of 45% in sprayed areas (t = 2.534, P = 0.026 (12 df». In order to decide whether bednets : should replace house spraying in South Africa, we need more : data on the efficacy of treated bednets, their long-term acceptability and the cost of the two interventions
Light echoes reveal an unexpectedly cool Eta Carinae during its 19th-century Great Eruption
Eta Carinae (Eta Car) is one of the most massive binary stars in the Milky
Way. It became the second-brightest star in the sky during its mid-19th century
"Great Eruption," but then faded from view (with only naked-eye estimates of
brightness). Its eruption is unique among known astronomical transients in that
it exceeded the Eddington luminosity limit for 10 years. Because it is only 2.3
kpc away, spatially resolved studies of the nebula have constrained the ejected
mass and velocity, indicating that in its 19th century eruption, Eta Car
ejected more than 10 M_solar in an event that had 10% of the energy of a
typical core-collapse supernova without destroying the star. Here we report the
discovery of light echoes of Eta Carinae which appear to be from the 1838-1858
Great Eruption. Spectra of these light echoes show only absorption lines, which
are blueshifted by -210 km/s, in good agreement with predicted expansion
speeds. The light-echo spectra correlate best with those of G2-G5 supergiant
spectra, which have effective temperatures of ~5000 K. In contrast to the class
of extragalactic outbursts assumed to be analogs of Eta Car's Great Eruption,
the effective temperature of its outburst is significantly cooler than allowed
by standard opaque wind models. This indicates that other physical mechanisms
like an energetic blast wave may have triggered and influenced the eruption.Comment: Accepted for publication by Nature; 4 pages, 4 figures, SI: 6 pages,
3 figures, 5 table
A Kato type Theorem for the inviscid limit of the Navier-Stokes equations with a moving rigid body
The issue of the inviscid limit for the incompressible Navier-Stokes
equations when a no-slip condition is prescribed on the boundary is a famous
open problem. A result by Tosio Kato says that convergence to the Euler
equations holds true in the energy space if and only if the energy dissipation
rate of the viscous flow in a boundary layer of width proportional to the
viscosity vanishes. Of course, if one considers the motion of a solid body in
an incompressible fluid, with a no-slip condition at the interface, the issue
of the inviscid limit is as least as difficult. However it is not clear if the
additional difficulties linked to the body's dynamic make this issue more
difficult or not. In this paper we consider the motion of a rigid body in an
incompressible fluid occupying the complementary set in the space and we prove
that a Kato type condition implies the convergence of the fluid velocity and of
the body velocity as well, what seems to indicate that an answer in the case of
a fixed boundary could also bring an answer to the case where there is a moving
body in the fluid
On the flow map for 2D Euler equations with unbounded vorticity
In Part I, we construct a class of examples of initial velocities for which
the unique solution to the Euler equations in the plane has an associated flow
map that lies in no Holder space of positive exponent for any positive time. In
Part II, we explore inverse problems that arise in attempting to construct an
example of an initial velocity producing an arbitrarily poor modulus of
continuity of the flow map.Comment: http://iopscience.iop.org/0951-7715/24/9/013/ for published versio
Introduction: animal law in a nutshell
The introduction explains key concepts and methods. It defines global animal law as the sum of legal rules and principles governing the interactions between humans and other animals, on a domestic, local, regional, and international level. Global animal law reacts to the mismatch between almost exclusively national animal-related legislation on the one hand, and the global dimension of the animal issue on the other hand. The merely national regulation of animal welfare within the states’ boundaries runs aloof in the face of globalisation. This gives rise to an animal welfare gap. Moreover, animal use creates global problems ranging from climate and soil degradation over antimicrobial resistance to food insecurity. This requires a global law response. The introduction also gives a brief overview over the book and its main findings
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