Spectrophotometric calibration of low-resolution spectra

Low-resolution spectroscopy is a frequently used technique. Aperture prism spectroscopy in particular is an important tool for large-scale survey observations. The ongoing ESA space mission Gaia is the currently most relevant example. In this work we analyse the fundamental limitations of the calibration of low-resolution spectrophotometric observations and introduce a calibration method that avoids simplifying assumptions on the smearing effects of the line spread functions. To this aim, we developed a functional analytic mathematical formulation of the problem of spectrophotometric calibration. In this formulation, the calibration process can be described as a linear mapping between two suitably constructed Hilbert spaces, independently of the resolution of the spectrophotometric instrument. The presented calibration method can provide a formally unusual but precise calibration of low-resolution spectrophotometry with non-negligible widths of line spread functions. We used the Gaia spectrophotometric instruments to demonstrate that the calibration method of this work can potentially provide a significantly better calibration than methods neglecting the smearing effects of the line spread functions.Comment: Final versio

Effect of the heat dissipation system on hard-switching GaN-based power converters for energy conversion

The design of a cooling system is critical in power converters based on wide-bandgap (WBG) semiconductors. The use of gallium nitride enhancement-mode high-electron-mobility transistors (GaN e-HEMTs) is particularly challenging due to their small size and high power capability. In this paper, we model, study and compare the different heat dissipation systems proposed for high power density GaN-based power converters. Two dissipation systems are analysed in detail: bottom-side dissipation using thermal vias and top-side dissipation using different thermal interface materials. The effectiveness of both dissipation techniques is analysed using MATLAB/Simulink and PLECS. Furthermore, the impact of the dissipation system on the parasitic elements of the converter is studied using advanced design systems (ADS). The experimental results of the GaN-based converters show the effectiveness of the analysed heat dissipation systems and how top-side cooled converters have the lowest parasitic inductance among the studied power converters.This work was supported by the Industrial Doctorates Plan of the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya, the Centro para el Desarrollo Tecnológico Industrial (IDI-20200864), and the Ministerio de Ciencia, Innovación y Universidades of Spain within the project PID2019-111420RB-I00Peer ReviewedPostprint (published version

Endoscopic Management of Drain Inclusion in the Gastric Pouch after Gastrojejunal Leakage after Laparoscopic Roux-en-Y Gastric Bypass for the Treatment of Morbid Obesity (LRYGBP)

Background. Drain inclusion inside the gastric pouch is rare and can represent an important source of morbidity and mortality associated with laparocopic Roux-en-Y gastric bypass (LRYGBP). These leaks can become chronic and challenging. Surgical options are often unsuccessful. We present the endoscopic management of four patients with drain inclusion. Patients. All four obese morbidly patients underwent LRYGBP and presented a gastro-jejunal fistula after acute anastomotic leakage. During follow-up endoscopy the drain was found inside the gastric pouch. It was moved into the abdominal cavity. Fistula debit reduced significantly and closed. Results. Gastric leak closure in less than 24 hours was achieved in all, with complete resolution of symptoms. These patients benefited exclusively from endoscopic treatment. Conclusions. Endoscopy is useful and technically feasible in chronic fistulas. This procedure is a less invasive alternative to traditional surgical revision. Other therapeutic strategies can be used such as clips and fibrin glue. Drains should not be placed in contact with the anastomosis or stapled lines. Drain inclusion must be suspected when fistula debit suddenly arises. If so, endoscopy is indicated for diagnostic accuracy. Under endoscopy vision, the drain is gently removed from the gastric reservoir leading to sudden and complete resolution of the fistula

Sensitive quantification of the HIV-1 reservoir in gut-associated lymphoid tissue

Background: The implementation of successful strategies to achieve an HIV cure has become a priority in HIV research. However, the current location and size of HIV reservoirs is still unknown since there are limited tools to evaluate HIV latency in viral sanctuaries such as gut-associated lymphoid tissue (GALT). As reported in the so called "Boston Patients", despite undetectable levels of proviral HIV-1 DNA in blood and GALT, viral rebound happens in just few months after ART interruption. This fact might imply that current methods are not sensitive enough to detect residual reservoirs. Showing that, it is imperative to improve the detection and quantification of HIV-1 reservoir in tissue samples. Herein, we propose a novel non-enzymatic protocol for purification of Lamina Propria Leukocytes (LPL) from gut biopsies combined to viral HIV DNA (vDNA) quantification by droplet digital PCR (ddPCR) to improve the sensitivity and accuracy of viral reservoir measurements (LPL-vDNA assay). Methods: Endoscopic ileum biopsies were sampled from 12 HIV-1-infected cART-suppressed subjects. We performed a DTT/EDTA-based treatment for epithelial layer removal followed by non-enzymatic disruption of the tissue to obtain lamina propria cell suspension (LP). CD45+ cells were subsequently purified by flow sorting and vDNA was determined by ddPCR. Results: vDNA quantification levels were significantly higher in purified LPLs (CD45+) than in bulk LPs (p<0.01). The levels of vDNA were higher in ileum samples than in concurrent PBMC from the same individuals (p = 0.002). As a result of the increased sensitivity of this purification method, the Poisson 95% confidence intervals of the vDNA quantification data from LPLs were narrower than that from bulk LPs. Of note, vDNA was unambiguously quantified above the detection limit in 100% of LPL samples, while only in 58% of bulk LPs. Conclusion: We propose an innovative combined protocol for a more sensitive detection of the HIV reservoir in gut-associated viral sanctuaries, which might be used to evaluate any proposed eradication strategy

Sensitive quantification of the HIV-1 reservoir in gut-associated lymphoid tissue

Altres ajuts: This substudy was supported by ViiV and the American Foundation for AIDS Research(amfAR)(ARCHE). IrsiCaixa was supported by the CERCA programme from Generalitat de Catalunya.Background. The implementation of successful strategies to achieve an HIV cure has become a priority in HIV research. However, the current location and size of HIV reservoirs is still unknown since there are limited tools to evaluate HIV latency in viral sanctuaries such as gut-associated lymphoid tissue (GALT). As reported in the so called "Boston Patients", despite undetectable levels of proviral HIV-1 DNA in blood and GALT, viral rebound happens in just few months after ART interruption. This fact might imply that current methods are not sensitive enough to detect residual reservoirs. Showing that, it is imperative to improve the detection and quantification of HIV-1 reservoir in tissue samples. Herein, we propose a novel nonenzymatic protocol for purification of Lamina Propria Leukocytes (LPL) from gut biopsies combined to viral HIV DNA (vDNA) quantification by droplet digital PCR (ddPCR) to improve the sensitivity and accuracy of viral reservoir measurements (LPL-vDNA assay). Methods. Endoscopic ileum biopsies were sampled from 12 HIV-1-infected cART- suppressed subjects. We performed a DTT/EDTA-based treatment for epithelial layer removal followed by non-enzymatic disruption of the tissue to obtain lamina propria cell suspension (LP). CD45+ cells were subsequently purified by flow sorting and vDNA was determined by ddPCR. Results. vDNA quantification levels were significantly higher in purified LPLs (CD45+) than in bulk LPs (p<0.01). The levels of vDNA were higher in ileum samples than in concurrent PBMC from the same individuals (p = 0.002). As a result of the increased sensitivity of thispurification method, the Poisson 95% confidence intervals of the vDNA quantification data from LPLs were narrower than that from bulk LPs. Of note, vDNA was unambiguously quantified above the detection limit in 100% of LPL samples, while only in 58% of bulk LPs. Conclusion. We propose an innovative combined protocol for a more sensitive detection of the HIV reservoir in gut-associated viral sanctuaries, which might be used to evaluate any proposed eradication strategy

Gaia Photometric Data: DR1 results and DR2 expectations

Gaia DR1 was released in September 2016 and contained a photometric catalogue of over 1 billion sources. At this stage, this only included mean G-band photometry and an estimate of the error. Even though this may sound limited in nature, interesting science can still be achieved with this data thanks to its quality. A high level overview of the photometric processing and some validation results will be presented. Additionally, epoch photometry in the G-band was released in Gaia DR1 for a small number of variable sources in the South Ecliptic Pole which covers the LMC. The second data release (Gaia DR2) is currently being prepared and, if available, some preliminary validation results will be presented. It is planned that this release will contain colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry

Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations

Photometric Catalogue for Space and Ground Night-Time Remote-Sensing Calibration: RGB Synthetic Photometry from <i>Gaia</i> DR3 Spectrophotometry

Recent works have made strong efforts to produce standardised photometry in RGB bands. For this purpose, we carefully defined the transmissivity curves of RGB bands and defined a set of standard sources using the photometric information present in Gaia EDR3. This work aims not only to significantly increase the number and accuracy of RGB standards but also to provide, for the first time, reliable uncertainty estimates using the BP and RP spectrophotometry published in Gaia DR3 instead of their integrated photometry to predict RGB photometry. Furthermore, this method allows including calibrated sources regardless of how they are affected by extinction, which was a major shortcoming of previous work. The RGB photometry is synthesised from the Gaia BP and RP low-resolution spectra by directly using their set of coefficients multiplied with some basis functions provided in the Gaia catalogue for all sources published in Gaia DR3. The output synthetic magnitudes are compared with the previous catalogue of RGB standards available

RGB photometric calibration of 15 million Gaia stars

Although a catalogue of synthetic RGB magnitudes, providing photometric data for a sample of 1346 bright stars, has been recently published, its usefulness is still limited due to the small number of reference stars available, considering that they are distributed throughout the whole celestial sphere, and the fact that they are restricted to Johnson V < 6.6 mag. This work presents synthetic RGB magnitudes for ∼15 million stars brighter than Gaia G = 18 mag, making use of a calibration between the RGB magnitudes of the reference bright star sample and the corresponding high-quality photometric G, GBP, and GRP magnitudes provided by the Gaia EDR3. The calibration has been restricted to stars exhibiting -0.5 < GBP - GRP < 2.0 mag, and aims to predict RGB magnitudes within an error interval of ±0.1 mag. Since the reference bright star sample is dominated by nearby stars with slightly undersolar metallicity, systematic variations in the predictions are expected, as modelled with the help of stellar atmosphere models. These deviations are constrained to the ±0.1-mag interval when applying the calibration only to stars scarcely affected by interstellar extinction and with metallicity compatible with the median value for the bright star sample. The large number of Gaia sources available in each region of the sky should guarantee high-quality RGB photometric calibrations. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.The authors acknowledge financial support from the Spanish Programa Estatal de I+D + i Orientada a los Retos de la Sociedad under grant RTI2018-096188B-I00, which is partly funded by the European Regional Development Fund (ERDF), S2018/NMT-4291 (TEC2SPACE-CM), and ACTION, a project funded by the European Union H2020-SwafS-2018-1-824603. The participation of ICCUB researchers was (partially) supported by the Spanish Ministry of Science, Innovation and University (MICIU/FEDER, UE) through grant RTI2018095076-B-C21, and the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia 'María de Maeztu') through grant CEX2019-000918-M. SB acknowledges Xunta de Galicia for financial support under grant ED431B 2020/29. The participation of ASdM was (partially) supported by the EMISSI@N project (NERC grant NE/P01156X/1). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.Peer reviewe