1,195 research outputs found
Multimode quantum interference of photons in multiport integrated devices
We report the first demonstration of quantum interference in multimode
interference (MMI) devices and a new complete characterization technique that
can be applied to any photonic device that removes the need for phase stable
measurements. MMI devices provide a compact and robust realization of NxM
optical circuits, which will dramatically reduce the complexity and increase
the functionality of future generations of quantum photonic circuits
Use of the industrial property system in Colombia (2018): A supervised learning application
The purpose of this paper is to establish ways to predict the spatial distribution of the use of the intellectual property system from information on industrial property applications and grants (distinctive signs and new creations) and copyright registrations in 2018. This will be done using supervised learning algorithms applied to information on industrial property applications and grants (trademarks and new creations) and copyright registrations in 2018. Within the findings, 4 algorithms were identified with a level of explanation higher than 80%: (i) Linear Regression, with an elastic network regularization; (ii) Stochastic Gradient Descent, with Hinge loss function, Ringe regularization (L2) and a constant learning rate; (iii) Neural Networks, with 1,000 layers, with Adam’s solution algorithm and 2,000 iterations; (iv) Random Forest, with 10 tree
Efficient coupling of photons to a single molecule and the observation of its resonance fluorescence
Single dye molecules at cryogenic temperatures display many spectroscopic
phenomena known from free atoms and are thus promising candidates for
fundamental quantum optical studies. However, the existing techniques for the
detection of single molecules have either sacrificed the information on the
coherence of the excited state or have been inefficient. Here we show that
these problems can be addressed by focusing the excitation light near to the
absorption cross section of a molecule. Our detection scheme allows us to
explore resonance fluorescence over 9 orders of magnitude of excitation
intensity and to separate its coherent and incoherent parts. In the strong
excitation regime, we demonstrate the first observation of the Mollow triplet
from a single solid-state emitter. Under weak excitation we report the
detection of a single molecule with an incident power as faint as 150 attoWatt,
paving the way for studying nonlinear effects with only a few photons.Comment: 6 figure
'It is like a tomato stall where someone can pick what he likes': structure and practices of female sex work in Kampala, Uganda.
BACKGROUND: Effective interventions among female sex workers require a thorough knowledge of the context of local sex industries. We explore the organisation of female sex work in a low socio-economic setting in Kampala, Uganda. METHODS: We conducted a qualitative study with 101 participants selected from an epidemiological cohort of 1027 women at high risk of HIV in Kampala. Repeat in-depth life history and work practice interviews were conducted from March 2010 to June 2011. Context specific factors of female sex workers' day-to-day lives were captured. Reported themes were identified and categorised inductively. RESULTS: Of the 101 women, 58 were active self-identified sex workers operating in different locations within the area of study and nine had quit sex work. This paper focuses on these 67 women who gave information about their involvement in sex work. The majority had not gone beyond primary level of education and all had at least one child. Thirty one voluntarily disclosed that they were HIV-positive. Common sex work locations were streets/roadsides, bars and night clubs. Typically sex occurred in lodges near bars/night clubs, dark alleyways or car parking lots. Overall, women experienced sex work-related challenges at their work locations but these were more apparent in outdoor settings. These settings exposed women to violence, visibility to police, a stigmatising public as well as competition for clients, while bars provided some protection from these challenges. Older sex workers tended to prefer bars while the younger ones were mostly based on the streets. Alcohol consumption was a feature in all locations and women said it gave them courage and helped them to withstand the night chill. Condom use was determined by clients' willingness, a woman's level of sobriety or price offered. CONCLUSIONS: Sex work operates across a variety of locations in the study area in Kampala, with each presenting different strategies and challenges for those operating there. Risky practices are present in all locations although they are higher on the streets compared to other locations. Location specific interventions are required to address the complex challenges in sex work environments
Measurement-Induced Entanglement for Excitation Stored in Remote Atomic Ensembles
A critical requirement for diverse applications in Quantum Information
Science is the capability to disseminate quantum resources over complex quantum
networks. For example, the coherent distribution of entangled quantum states
together with quantum memory to store these states can enable scalable
architectures for quantum computation, communication, and metrology. As a
significant step toward such possibilities, here we report observations of
entanglement between two atomic ensembles located in distinct apparatuses on
different tables. Quantum interference in the detection of a photon emitted by
one of the samples projects the otherwise independent ensembles into an
entangled state with one joint excitation stored remotely in 10^5 atoms at each
site. After a programmable delay, we confirm entanglement by mapping the state
of the atoms to optical fields and by measuring mutual coherences and photon
statistics for these fields. We thereby determine a quantitative lower bound
for the entanglement of the joint state of the ensembles. Our observations
provide a new capability for the distribution and storage of entangled quantum
states, including for scalable quantum communication networks .Comment: 13 pages, 4 figures Submitted for publication on August 31 200
Photonic quantum technologies
The first quantum technology, which harnesses uniquely quantum mechanical
effects for its core operation, has arrived in the form of commercially
available quantum key distribution systems that achieve enhanced security by
encoding information in photons such that information gained by an eavesdropper
can be detected. Anticipated future quantum technologies include large-scale
secure networks, enhanced measurement and lithography, and quantum information
processors, promising exponentially greater computation power for particular
tasks. Photonics is destined for a central role in such technologies owing to
the need for high-speed transmission and the outstanding low-noise properties
of photons. These technologies may use single photons or quantum states of
bright laser beams, or both, and will undoubtably apply and drive
state-of-the-art developments in photonics
Smoking and health-related quality of life in English general population: Implications for economic evaluations
Copyright @ 2012 Vogl et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: Little is known as to how health-related quality of life (HRQoL) when measured by generic instruments such as EQ-5D differ across smokers, ex-smokers and never-smokers in the general population; whether the overall pattern of this difference remain consistent in each domain of HRQoL; and what implications this variation, if any, would have for economic evaluations of tobacco control interventions. Methods: Using the 2006 round of Health Survey for England data (n = 13,241), this paper aims to examine the impact of smoking status on health-related quality of life in English population. Depending upon the nature of the EQ-5D data (i.e. tariff or domains), linear or logistic regression models were fitted to control for biology, clinical conditions, socio-economic background and lifestyle factors that an individual may have regardless of their smoking status. Age- and gender-specific predicted values according to smoking status are offered as the potential 'utility' values to be used in future economic evaluation models. Results: The observed difference of 0.1100 in EQ-5D scores between never-smokers (0.8839) and heavy-smokers (0.7739) reduced to 0.0516 after adjusting for biological, clinical, lifestyle and socioeconomic conditions. Heavy-smokers, when compared with never-smokers, were significantly more likely to report some/severe problems in all five domains - mobility (67%), self-care (70%), usual activity (42%), pain/discomfort (46%) and anxiety/depression (86%) -. 'Utility' values by age and gender for each category of smoking are provided to be used in the future economic evaluations. Conclusion: Smoking is significantly and negatively associated with health-related quality of life in English general population and the magnitude of this association is determined by the number of cigarettes smoked. The varying degree of this association, captured through instruments such as EQ-5D, may need to be fed into the design of future economic evaluations where the intervention being evaluated affects (e.g. tobacco control) or is affected (e.g. treatment for lung cancer) by individual's (or patients') smoking status
Von Bezold assimilation effect reverses in stereoscopic conditions
Lightness contrast and lightness assimilation are opposite phenomena: in contrast,
grey targets appear darker when bordering bright surfaces (inducers) rather than dark ones; in
assimilation, the opposite occurs. The question is: which visual process favours the occurrence
of one phenomenon over the other? Researchers provided three answers to this question. The
first asserts that both phenomena are caused by peripheral processes; the second attributes their
occurrence to central processes; and the third claims that contrast involves central processes,
whilst assimilation involves peripheral ones. To test these hypotheses, an experiment on an IT
system equipped with goggles for stereo vision was run. Observers were asked to evaluate the
lightness of a grey target, and two variables were systematically manipulated: (i) the apparent
distance of the inducers; and (ii) brightness of the inducers. The retinal stimulation was kept
constant throughout, so that the peripheral processes remained the same. The results show that
the lightness of the target depends on both variables. As the retinal stimulation was kept constant, we
conclude that central mechanisms are involved in both lightness contrast and lightness assimilation
Bilayer manganites: polarons in the midst of a metallic breakdown
The exact nature of the low temperature electronic phase of the manganite
materials family, and hence the origin of their colossal magnetoresistant (CMR)
effect, is still under heavy debate. By combining new photoemission and
tunneling data, we show that in La{2-2x}Sr{1+2x}Mn2O7 the polaronic degrees of
freedom win out across the CMR region of the phase diagram. This means that the
generic ground state is that of a system in which strong electron-lattice
interactions result in vanishing coherent quasi-particle spectral weight at the
Fermi level for all locations in k-space. The incoherence of the charge
carriers offers a unifying explanation for the anomalous charge-carrier
dynamics seen in transport, optics and electron spectroscopic data. The
stacking number N is the key factor for true metallic behavior, as an
intergrowth-driven breakdown of the polaronic domination to give a metal
possessing a traditional Fermi surface is seen in the bilayer system.Comment: 7 pages, 2 figures, includes supplementary informatio
Galactic kinematics from RAVE to Gaia-RVS Data
RAVE data has provided new results on Galactic kinematics like the kinematical decomposition of the Galactic disk. This decomposition permits to identify the different components of the disk and to characterize them in terms of scale height and scale length. With the data provided by Gaia and in particular the RVS, we will have a completly renewed view of the Galaxy. The precision of the RVS will permit to undertake a precise analysis of the kinematics of the Galactic disks. This knowledge will provide significant clues to constrain the scenarios of the Galactic disk formation
- …