2,501 research outputs found
Helico-conical optical beams self-heal
An optical beam is said to be self-healing when, distorted by an obstacle,
the beam corrects itself upon propagation. In this letter, we show through
experiments supported by numerical simulations, that Helico-conical optical
beams (HCOBs) self-heal. We observe the strong resilience of these beams with
different types of obstructions, and relate this to the characteristics of
their transverse energy flow.Comment: 4 pages, 5 figure
Field squeeze operators in optical cavities with atomic ensembles
We propose a method of generating unitarily single and two-mode field
squeezing in an optical cavity with an atomic cloud. Through a suitable laser
system, we are able to engineer a squeeze field operator decoupled from the
atomic degrees of freedom, yielding a large squeeze parameter that is scaled up
by the number of atoms, and realizing degenerate and non-degenerate parametric
amplification. By means of the input-output theory we show that ideal squeezed
states and perfect squeezing could be approached at the output. The scheme is
robust to decoherence processes.Comment: Four pages and one figure. Accepted in Physical Review Letter
Using Ignatian Pedagogy in a Mediation Course
In this article, I describe how I designed a mediation course applying the Ignatian Pedagogical Paradigm (IPP). I share examples of some of the assignments and activities as well as narratives of students evidencing how by combining the five tenets of IPP—context, experience, reflection, action, and evaluation—students achieve professional, spiritual, and personal growth
Analysis Of The Cyclability Of Lithium-polymer Batteries
Comunicación y póster en congresoLithium ion batteries and similar energy storage devices have an increasing importance for the modern society as they are present in many portable electronic devices and have perspectives in the fields of electric vehicles and renewable energy accumulation.
Herein, we present results from charge and discharge cycles on batteries under controlled conditions. The cyclability of commercial lithium-polymer pouch batteries under different charge/discharge rates and temperatures was studied. Based on the results, the relationship between the state of charge and the cell voltage was obtained, as well as degradation of the cells, i.e., the decrease of the energy capacity after a number of cycles.
The experimental results were compared with simulations based on Newman's model for Lithium Ion Batteries, carried out using the COMSOL Multiphysics® software. The batteries and fuel cell and the heat transfer modules were use to couple between the temperature and the electrochemical interactions. The results show the correlation between temperature, C-rate and degradation in lithium ion batteries. It is specially remarkable the decrease of the apparent capacity of batteries at low temperatures, and the increase of the degradation at higher temperatures. These results are essential for the design of mechanisms that could prevent battery failure.The authors acknowledge the financial support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045, and the "Plan Propio de Investigación y Transferencia de la Universidad de Málaga", code: PPIT.UMA.B5.2018/17
Shape coexistence in Lead isotopes in the interacting boson model with Gogny energy density functional
We investigate the emergence and evolution of shape coexistence in the
neutron-deficient Lead isotopes within the interacting boson model (IBM) plus
configuration mixing with microscopic input based on the Gogny energy density
functional (EDF). The microscopic potential energy surface obtained from the
constrained self-consistent Hartree-Fock-Bogoliubov method employing the
Gogny-D1M EDF is mapped onto the coherent-state expectation value of the
configuration-mixing IBM Hamiltonian. In this way, the parameters of the IBM
Hamiltonian are fixed for each of the three relevant configurations (spherical,
prolate and oblate) associated to the mean field minima. Subsequent
diagonalization of the Hamiltonian provides the excitation energy of the
low-lying states and transition strengths among them. The model predictions for
the level energies and evolving shape coexistence in the considered
Lead chain are consistent both with experiment and with the indications of the
Gogny-EDF energy surfaces.Comment: 12 pages, 6 figures, 1 tabl
Pillars of creation amongst destruction: Star formation in molecular clouds near R136 in 30 Doradus
New sensitive CO(2-1) observations of the 30 Doradus region in the Large
Magellanic Cloud are presented. We identify a chain of three newly discovered
molecular clouds we name KN1, KN2 and KN3 lying within 2--14 pc in projection
from the young massive cluster R136 in 30 Doradus. Excited H 2.12m
emission is spatially coincident with the molecular clouds, but ionized
Br emission is not. We interpret these observations as the tails of
pillar-like structures whose ionized heads are pointing towards R136. Based on
infrared photometry, we identify a new generation of stars forming within this
structure.Comment: Accepted for publication in ApJ (includes 13 pages, 8 figures). For
higher resolution figures please see
http://www.das.uchile.cl/~vkalari/staplervk.pd
An integrated approach toward the incorporation of clouds in the temperature retrievals from microwave measurements
In this paper, we address the characterization of clouds and its inclusion in
microwave retrievals in order to study its effect on tropospheric temperature
profiles measured by TEMPERA radiometer. TEMPERA is the first ground-based
microwave radiometer that makes it possible to obtain temperature profiles in the
troposphere and stratosphere at the same time. In order to characterize the
clouds a multi-instrumental approach has been adopted. Cloud base altitudes
were detected using ceilometer measurements while the integrated liquid water
was measured by TROWARA radiometer. Both instruments are co-located with
TEMPERA in Bern (Switzerland). Using this information and a constant Liquid
Water Content value inside the cloud a liquid profile is provided to
characterize the clouds in the inversion algorithm. Microwave temperature
profiles have been obtained incorporating this water liquid profile in the
inversion algorithm and also without considering the clouds, in order to
assess its effect on the retrievals. The results have been compared with the
temperature profiles from radiosondes which are launched twice a day at the
aerological station of MeteoSwiss in Payerne (40 km W of Bern). Almost 1
year of data have been analysed and 60 non-precipitating cloud cases were
studied. The statistical analysis carried out over all the cases evidenced
that temperature retrievals improved in most of the cases when clouds were
incorporated in the inversion algorithm
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