685 research outputs found
Conversion of bright magneto-optical resonances into dark at fixed laser frequency for D2 excitation of atomic rubidium
Nonlinear magneto-optical resonances on the hyperfine transitions belonging
to the D2 line of rubidium were changed from bright to dark resonances by
changing the laser power density of the single exciting laser field or by
changing the vapor temperature in the cell. In one set of experiments atoms
were excited by linearly polarized light from an extended cavity diode laser
with polarization vector perpendicular to the light's propagation direction and
magnetic field, and laser induced fluorescence (LIF) was observed along the
direction of the magnetic field, which was scanned. A low-contrast bright
resonance was observed at low laser power densities when the laser was tuned to
the Fg=2 --> Fe=3 transition of Rb-87 and near to the Fg=3 --> Fe=4 transition
of Rb-85. The bright resonance became dark as the laser power density was
increased above 0.6mW/cm2 or 0.8 mW/cm2, respectively. When the Fg=2 --> Fe=3
transition of Rb-87 was excited with circularly polarized light in a second set
of experiments, a bright resonance was observed, which became dark when the
temperature was increased to around 50C. The experimental observations at room
temperature could be reproduced with good agreement by calculations based on a
theoretical model, although the theoretical model was not able to describe
measurements at elevated temperatures, where reabsorption was thought to play a
decisive role. The model was derived from the optical Bloch equations and
included all nearby hyperfine components, averaging over the Doppler profile,
mixing of magnetic sublevels in the external magnetic field, and a treatment of
the coherence properties of the exciting radiation field.Comment: 9 pages, 7 figure
Adjuvant Radiotherapy for Groin Node Metastases Following Surgery for Vulvar Cancer: A Systematic Review
Background: Lymph node metastasis in vulvar cancer is a critical prognostic factor associated with higher recurrence and decreased survival. A survival benefit is reported with adjuvant radiotherapy but with potential significant morbidity. We aim to clarify whether there is high-quality evidence to support the use of adjuvant radiotherapy in this setting. Objectives: The aim of the study was to assess the effectiveness and safety of adjuvant radiotherapy to locoregional metastatic nodal areas. Search Methods: We conducted a comprehensive and systematic literature search of MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Google Scholar, ClinicalTrials.gov, and the National Cancer Institute. We considered only randomized controlled trials (RCTs). Main Results: We identified 1,760 records and finally retrieved only one eligible RCT (114 participants with positive inguinofemoral lymph nodes). All women had undergone radical vulvectomy and bilateral inguinal lymphadenectomy and had been randomized to adjuvant radiotherapy or to intraoperative ipsilateral pelvic lymphadenectomy without adjuvant radiotherapy. At 6 years, the overall survival (OS) was 51% versus 41% in favor of radiotherapy (HR 0.61; 95% CI 0.30–1.3) without significance and with very low certainty of evidence. At 6 year, the cumulative incidence of cancer-related deaths was 29% versus 51% in favor of adjuvant radiotherapy (HR 0.49; 95% CI 0.28–0.87). Recurrence-free survival at 6 years was 59% after adjuvant radiotherapy versus 48% after pelvic lymphadenectomy (HR 0.39; 95% CI 0.17–0.88). Three (5.3%) versus 13 (24.1%) groin recurrences were noted, respectively, in the adjuvant radiotherapy and pelvic lymphadenectomy groups. There was no significant difference in acute toxicities for pelvic lymphadenectomy compared to radiotherapy. In women with positive pelvic lymph nodes (20%), the OS at 6 year was 36% compared with 13% in favor of adjuvant radiotherapy. Late cutaneous toxicity rate appeared to be greater after radiotherapy (19% vs. 15%) but with less chronic lymphedema (16% vs. 22%). Conclusion: There is only very low-quality evidence on administering adjuvant radiotherapy for inguinal lymph node metastases. Although the identified study was a multicenter RCT, there was a reasonable imprecision and inconsistency because of small study numbers, wide confidence intervals in the data, and early trial closure, resulting in downgrading of the evidence
Optical response of a misaligned and suspended Fabry-Perot cavity
The response to a probe laser beam of a suspended, misaligned and detuned
optical cavity is examined. A five degree of freedom model of the fluctuations
of the longitudinal and transverse mirror coordinates is presented. Classical
and quantum mechanical effects of radiation pressure are studied with the help
of the optical stiffness coefficients and the signals provided by an FM
sideband technique and a quadrant detector, for generic values of the product
of the fluctuation frequency times the cavity round trip. A
simplified version is presented for the case of small misalignments. Mechanical
stability, mirror position entanglement and ponderomotive squeezing are
accommodated in this model. Numerical plots refer to cavities under test at the
so-called Pisa LF facility.Comment: 14 pages (4 figures) submitted to Phys. Rev.
Cascade coherence transfer and magneto-optical resonances at 455 nm excitation of Cesium
We present and experimental and theoretical study of nonlinear
magneto-optical resonances observed in the fluorescence to the ground state
from the 7P_{3/2} state of cesium, which was populated directly by laser
radiation at 455 nm, and from the 6P_{1/2} and 6P_{3/2} states, which were
populated via cascade transitions that started from the 7P_{3/2} state and
passed through various intermediate states. The laser-induced fluorescence
(LIF) was observed as the magnetic field was scanned through zero. Signals were
recorded for the two orthogonal, linearly polarized components of the LIF. We
compared the measured signals with the results of calculations from a model
that was based on the optical Bloch equations and averaged over the Doppler
profile. This model was adapted from a model that had been developed for D_1
and D_2 excitation of alkali metal atoms. The calculations agree quite well
with the measurements, especially when taking into account the fact that some
experimental parameters were only estimated in the model.Comment: small changes to text of previous version; 12 pages, 8 figure
Draw me a Neutrino: the first KM3NeT art contest
[EN] While the KM3NeT neutrino detector is being deployed in the Mediterranean Sea, the Collaboration
launched a contest searching for illustrations of the neutrinos it will detect. The participants
in the contest were invited to submit their interpretation of a neutrino, using any technique. More
than 500 drawings were submitted from sixteen different countries. The winners were selected
by a jury of scientists, artists and science communicators based on the originality and creativity
of the drawings, as well as the harmony with the properties and origin of the neutrinos. After
announcing the results in an online ceremony with a large international audience, the winning
drawings have been put on display in a dedicated KM3NeT Virtual Neutrino Art Centre. In this
contribution, we will explain the motivation for the contest and will describe how it was organized.
We will also show the winning drawings and present the results of an impact study carried out
during the contest.We thank Angelo Ceres of Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, for
setting up the contest website. The contest was supported in France from Centre National de la
Recherche Scientifique (CNRS) and LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX0001). G. de Wasseige acknowledges support from the European UnionÂżs Horizon 2020 research
and innovation programme under the Marie Sklodowska-Curie grant agreement No 844138.Circella, M.; Ardid RamĂrez, M.; Bendahman, M.; Bozza, C.; Coyle, P.; Wasseige, G.; Distefano, C.... (2022). Draw me a Neutrino: the first KM3NeT art contest. PoS. Proceedings of Science. 1-10. https://doi.org/10.22323/1.395.140011
Mirror quiescence and high-sensitivity position measurements with feedback
We present a detailed study of how phase-sensitive feedback schemes can be
used to improve the performance of optomechanical devices. Considering the case
of a cavity mode coupled to an oscillating mirror by the radiation pressure, we
show how feedback can be used to reduce the position noise spectrum of the
mirror, cool it to its quantum ground state, or achieve position squeezing.
Then, we show that even though feedback is not able to improve the sensitivity
of stationary position spectral measurements, it is possible to design a
nonstationary strategy able to increase this sensitivity.Comment: 25 pages, 11 figure
Continuous variable entanglement by radiation pressure
We show that the radiation pressure of an intense optical field impinging on
a perfectly reflecting vibrating mirror is able to entangle in a robust way the
first two optical sideband modes. Under appropriate conditions, the generated
entangled state is of EPR type [A. Einstein, {\it et al.}, Phys. Rev. {\bf 47},
777 (1935)].Comment: 11 pages, 3 figure
Entangling macroscopic oscillators exploiting radiation pressure
It is shown that radiation pressure can be profitably used to entangle {\it
macroscopic} oscillators like movable mirrors, using present technology. We
prove a new sufficient criterion for entanglement and show that the achievable
entanglement is robust against thermal noise. Its signature can be revealed
using common optomechanical readout apparatus.Comment: 4 pages, 2 eps figures, new separability criterion added, new figure
2, authors list change
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