Electrochemical integration of graphene with light absorbing copper-based thin films

We present an electrochemical route for the integration of graphene with light sensitive copper-based alloys used in optoelectronic applications. Graphene grown using chemical vapor deposition (CVD) transferred to glass is found to be a robust substrate on which photoconductive Cu_{x}S films of 1-2 um thickness can be deposited. The effect of growth parameters on the morphology and photoconductivity of Cu_{x}S films is presented. Current-voltage characterization and photoconductivity decay experiments are performed with graphene as one contact and silver epoxy as the other

Relational Quantum Mechanics

I suggest that the common unease with taking quantum mechanics as a fundamental description of nature (the "measurement problem") could derive from the use of an incorrect notion, as the unease with the Lorentz transformations before Einstein derived from the notion of observer-independent time. I suggest that this incorrect notion is the notion of observer-independent state of a system (or observer-independent values of physical quantities). I reformulate the problem of the "interpretation of quantum mechanics" as the problem of deriving the formalism from a few simple physical postulates. I consider a reformulation of quantum mechanics in terms of information theory. All systems are assumed to be equivalent, there is no observer-observed distinction, and the theory describes only the information that systems have about each other; nevertheless, the theory is complete.Comment: Substantially revised version. LaTeX fil

A big data approach to identify the loss of coastal cultural ecosystem services caused by the 2019 Brazilian oil spill disaster

In August 2019, the Northeast coast of Brazil was impacted by an extensive oil spill, with immediate effects on marine and coastal ecosystems and significant impacts on tourism and food security. The human dimension of those impacts also includes the loss of cultural ecosystem services (CES); the non-material benefits stemming from strongly rooted cultural practices and relationships with nature. CES are of great importance for local residents and visitors that flock to Brazilian iconic beaches, however, they are difficult to measure using traditional assessment methods due to their subjective and non-tangible nature. Here, we use a big data approach to assess and map the loss of CES in the Northeast coast of Brazil caused by the recent oil spill. We analysed 2,880 digital images (published on the image sharing platform Flickr) taken before and during the disaster in affected locations, using a combination of automated techniques. Results showed a sharp decline in the number of users posting photos of locations affected by oil spill, and a decline in photos representing landscape and cultural appreciation. Our big data approach provides a fast and automated way to assess CES at large spatial scales that can be used to monitor the social impacts of environmental disasters.Peer reviewe

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum