A comprehensive analysis of the (R13xR13)R13.9{\deg} type II structure of silicene on Ag(111)

In this paper, using the same geometrical approach than for the (2R3x2R3) R30{\deg} structure (H. Jamgotchian et al., 2015, Journal of Physics. Condensed Matter 27 395002), for the (R13xR13)R13.9{\deg} type II structure, we propose an atomic model of the silicene layer based on a periodic relaxation of the strain epitaxy. This relaxation creates periodic arrangements of perfect areas of (R13xR13)R13.9{\deg} type II structure surrounded by defect areas. A detailed analysis of the main published experimental results, obtained by Scanning Tunneling Microscopy and by Low Energy Electron Diffraction, shows a good agreement with the geometrical model.Comment: 20 pages, 9 figure

Multi-wave coherent control of a solid-state single emitter

The authors acknowledge support by the European Research Council Starting Grant 'PICSEN' contract no. 306387.Coherent control of individual two-level systems (TLSs) is at the basis of any implementation of quantum information. An impressive level of control is now achieved using nuclear, vacancies and charge spins. Manipulation of bright exciton transitions in semiconductor quantum dots (QDs) is less advanced, principally due to the sub-nanosecond dephasing. Conversely, owing to their robust coupling to light, one can apply tools of nonlinear spectroscopy to achieve all-optical command. Here, we report on the coherent manipulation of an exciton via multi-wave mixing. Specifically, we employ three resonant pulses driving a single InAs QD. The first two induce a four-wave mixing (FWM) transient, which is projected onto a six-wave mixing (SWM) depending on the delay and area of the third pulse, in agreement with analytical predictions. Such a switch enables to demonstrate the generation of SWM on a single emitter and to engineer the spectro-temporal shape of the coherent response originating from a TLS. These results pave the way toward multi-pulse manipulations of solid state qubits via implementing the NMR-like control schemes in the optical domain.PostprintPeer reviewe

CONCERTO: High-fidelity simulation of millimeter line emissions of galaxies and [CII] intensity mapping

The intensity mapping of the [CII] 158-μm line redshifted to the submillimeter window is a promising probe of the za>4 star formation and its spatial distribution into large-scale structures. To prepare the first-generation experiments (e.g., CONCERTO), we need realistic simulations of the submillimeter extragalactic sky in spectroscopy. We present a new version of the simulated infrared dusty extragalactic sky (SIDES) model including the main submillimeter lines around 1 mm (CO, [CII], [CI]). This approach successfully reproduces the observed line luminosity functions. We then use our simulation to generate CONCERTO-like cubes (125-305 GHz) and forecast the power spectra of the fluctuations caused by the various astrophysical components at those frequencies. Depending on our assumptions on the relation between the star formation rate and [CII] luminosity, and the star formation history, our predictions of the za∼6 [CII] power spectrum vary by two orders of magnitude. This highlights how uncertain the predictions are and how important future measurements will be to improve our understanding of this early epoch. SIDES can reproduce the CO shot noise recently measured at a4;100 GHz by the millimeter-wavelength intensity mapping experiment (mmIME). Finally, we compare the contribution of the different astrophysical components at various redshifts to the power spectra. The continuum is by far the brightest, by a factor of three to 100, depending on the frequency. At 300 GHz, the CO foreground power spectrum is higher than the [CII] one for our base scenario. At lower frequencies, the contrast between [CII] and extragalactic foregrounds is even worse. Masking the known galaxies from deep surveys should allow us to reduce the foregrounds to 20% of the [CII] power spectrum up to z∼ 6.5. However, this masking method will not be sufficient at higher redshifts. The code and the products of our simulation are released publicly, and can be used for both intensity mapping experiments and submillimeter continuum and line surveys

CONCERTO: Simulating the CO, [CII], and [CI] line emission of galaxies in a 117 deg2 field and the impact of field-to-field variance

In the submillimeter regime, spectral line scans and line intensity mapping (LIM) are new promising probes for the cold gas content and star formation rate of galaxies across cosmic time. However, both of these two measurements suffer from field-to-field variance. We study the effect of field-to-field variance on the predicted CO and [CII] power spectra from future LIM experiments such as CONCERTO, as well as on the line luminosity functions (LFs) and the cosmic molecular gas mass density that are currently derived from spectral line scans. We combined a 117 deg2 dark matter lightcone from the Uchuu cosmological simulation with the simulated infrared dusty extragalactic sky (SIDES) approach. The clustering of the dusty galaxies in the SIDES-Uchuu product is validated by reproducing the cosmic infrared background anisotropies measured by Herschel and Planck. We find that in order to constrain the CO LF with an uncertainty below 20%, we need survey sizes of at least 0.1 deg2. Furthermore, accounting for the field-to-field variance using only the Poisson variance can underestimate the total variance by up to 80%. The lower the luminosity is and the larger the survey size is, the higher the level of underestimate. At z < 3, the impact of field-to-field variance on the cosmic molecular gas density can be as high as 40% for the 4.6 arcmin2 field, but drops below 10% for areas larger than 0.2 deg2. However, at z > 3 the variance decreases more slowly with survey size and for example drops below 10% for 1 deg2 fields. Finally, we find that the CO and [CII] LIM power spectra can vary by up to 50% in 1 deg2 fields. This limits the accuracy of the constraints provided by the first 1 deg2 surveys. In addition the level of the shot noise power is always dominated by the sources that are just below the detection thresholds, which limits its potential for deriving number densities of faint [CII] emitters. We provide an analytical formula to estimate the field-to-field variance of current or future LIM experiments given their observed frequency and survey size. The underlying code to derive the field-to-field variance and the full SIDES-Uchuu products (catalogs, cubes, and maps) are publicly available

A wide field-of-view low-resolution spectrometer at APEX: Instrument design and scientific forecast

Context. Characterising the large-scale structure in the Universe from present times to the high redshift epoch of reionisation is essential to constraining the cosmology, the history of star formation, and reionisation, to measuring the gas content of the Universe, and to obtaining a better understanding of the physical processes that drive galaxy formation and evolution. Using the integrated emission from unresolved galaxies or gas clouds, line intensity mapping (LIM) provides a new observational window to measure the larger properties of structures. This very promising technique motivates the community to plan for LIM experiments. Aims. We describe the development of a large field-of-view instrument, named CONCERTO (for CarbON CII line in post-rEionisation and ReionisaTiOn epoch), operating in the range 130-310 GHz from the APEX 12-m telescope (5100 m above sea level). CONCERTO is a low-resolution spectrometer based on the lumped element kinetic inductance detectors (LEKID) technology. Spectra are obtained using a fast Fourier transform spectrometer (FTS), coupled to a dilution cryostat with a base temperature of 0.1 K. Two two kilo-pixel arrays of LEKID are mounted inside the cryostat that also contains the cold optics and the front-end electronics. Methods. We present, in detail, the technological choices leading to the instrumental concept, together with the design and fabrication of the instrument and preliminary laboratory tests on the detectors. We also give our best estimates for CONCERTO sensitivity and give predictions for two of the main scientific goals of CONCERTO, that is, a [CII]-intensity mapping survey and observations of galaxy clusters. Results. We provide a detailed description of the instrument design. Based on realistic comparisons with existing instruments developed by our group (NIKA, NIKA2, and KISS), and on the laboratory characterisation of our detectors, we provide an estimate for CONCERTO sensitivity on the sky. Finally, we describe, in detail, two of the main scientific goals offered by CONCERTO at APEX

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2- weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extraadrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis

An Indo-Pacific coral spawning database.

The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology

Antibody-mediated enhancement aggravates chikungunya virus infection and disease severity

The arthropod-transmitted chikungunya virus (CHIKV) causes a flu-like disease that is characterized by incapacitating arthralgia. The re-emergence of CHIKV and the continual risk of new epidemics have reignited research in CHIKV pathogenesis. Virus-specific antibodies have been shown to control virus clearance, but antibodies present at sub-neutralizing concentrations can also augment virus infection that exacerbates disease severity. To explore this occurrence, CHIKV infection was investigated in the presence of CHIKV-specific antibodies in both primary human cells and a murine macrophage cell line, RAW264.7. Enhanced attachment of CHIKV to the primary human monocytes and B cells was observed while increased viral replication was detected in RAW264.7 cells. Blocking of specific Fc receptors (FcγRs) led to the abrogation of these observations. Furthermore, experimental infection in adult mice showed that animals had higher viral RNA loads and endured more severe joint inflammation in the presence of sub-neutralizing concentrations of CHIKV-specific antibodies. In addition, CHIKV infection in 11 days old mice under enhancing condition resulted in higher muscles viral RNA load detected and death. These observations provide the first evidence of antibody-mediated enhancement in CHIKV infection and pathogenesis and could also be relevant for other important arboviruses such as Zika virus