39 research outputs found

    Catalytic Asymmetric Synthesis of Bicycloprolines by a 1,3-Dipolar Cycloaddition/Intramolecular Alkylation Strategy

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form inJournal of Organic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.joc.6b01100 to Published Work, see http://pubs.acs.org/page/policy/articlesonrequest/index.htmlThe diastereoselective one-pot synthesis of hexahydrocyclopenta [b] pyrrole derivatives (bicycloprolines) has been achieved by base-mediated reactions of (E)-tert-butyl 6-bromo-2-hexenoate with α-imino esters. The catalytic asymmetric version of this process has been efficiently achieved using the CuI/(R)-DTBM-Segphos complex as a catalyst following a two-step 1,3-dipolar cycloaddition/intramolecular alkylation sequence.Financial support of this work by the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (MINECO CTQ2012-35790 and MINECO/FEDER CTQ2015-66954-P) are gratefully acknowledged. M.G.-E. and A.P.-E. thank the MICINN for predoctoral fellowship

    La relación médico-paciente en el tratamiento de la diabetes tipo 1. Un estudio cualitativo

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    ObjetivosConocer las experiencias y las expectativas de pacientes con diabetes tipo 1 (DM1) y sus familiares sobre la relación que establecen con sus médicos y su influencia en la forma de afrontar la enfermedad y el tratamiento.DiseñoDiseño cualitativo a través de grupos focales realizado en 2001.EmplazamientoDistintos centros sanitarios de Granada y Sevilla.ParticipantesPacientes con DM1, familiars y/o cuidadores.MétodoMuestreo teórico con representación de los perfiles más característicos. Procedimiento de análisis cualitativo: asignación de códigos al texto, triangulación e interpretación de resultados.ResultadosLa relación médico-paciente influye decisivamente en la vivencia emocional de la enfermedad y en la manera en que los pacientes asumen el control. Los pacientes entrevistados aseguran que la relación con sus médicos está centrada en los signos y los síntomas de la enfermedad, y que el aspecto emocional se deja de lado. Es frecuente que los profesionales basen su comunicación en la reprimenda y en la amenaza. Los tratamientos se imponen más que se consensúan, y las posibilidades de participación en las decisiones clínicas son escasas. En consecuencia, los pacientes desarrollan estrategias para tomar sus propias decisiones sobre el tratamiento adaptándolo a su vida.ConclusionesDesean un modelo de relación con sus médicos en el que les escuchen, empaticen con su situación, comprendan los problemas que enfrentan para seguir el tratamiento, les transmitan ánimos y adapten sus recomendaciones a las circunstancias vitales y emocionales de cada paciente. Se prefiere a los profesionales que combinan la competencia técnica (incluida la dimensión relacional) con la humanidad y la amabilidad, y que asumen su corresponsabilidad en el éxito del tratamiento.ObjectivesTo know the experiences and expectations of diabetes mellitus type 1 (DM1) patients and their relatives as regards the relationships established with doctors, and the impact of such relationships on their strategies to cope with the disease and treatment.DesignQualitative design based on focus groups conducted in 2001.LocationSeveral health care centres in Granada and Seville, Spain.ParticipantsDM1 patients and their relatives and/or carers.MethodTheory-based sampling including the most representative profiles. Qualitative analysis procedure: text coding, triangulation and interpretation of results.ResultsDoctor/patient relationship highly influences the emotional experience of disease and the way patients gain control over it. Interviewed patients said that the relationship with doctors is focused on disease signs and symptoms, leaving emotional aspects aside. Very often, provider communication is built on recrimination and threat. Treatment is imposed rather than agreed, with scarce opportunities for participating in clinical decisions. Patients develop strategies to take their own decisions and adapting treatment to their daily life.ConclusionsPatients value a relationship model whereby providers listen and empathise with their situation, understand their difficulties in treatment compliance, encourage them, and adapt recommendations to the personal and emotional circumstances of each patient. They prefer doctors combining professional competence-including relational skills-with humanity and kindness, as well as being capable of assuming their co-responsibility in treatment success

    Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

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    We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) 3-rays. A significant correlation (>3σ) between X-rays and VHE 3-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy 3-rays and radio, with the radio lagging by more than 100 days, placing the 3-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE 3-rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock. © 2023. The Author(s). Published by the American Astronomical Society

    MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7

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    Context. Certain types of supernova remnants (SNRs) in our Galaxy are assumed to be PeVatrons, capable of accelerating cosmic rays (CRs) to ∼ PeV energies. However, conclusive observational evidence for this has not yet been found. The SNR G106.3+2.7, detected at 1- 100 TeV energies by different γ-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape, which can be divided into a head and a tail region with different physical conditions. However, in which region the 100 TeV emission is produced has not yet been identified because of the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear as to whether the origin of the γ-ray emission is leptonic or hadronic. Aims. With the better angular resolution provided by new MAGIC data compared to earlier γ-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1 resolution at TeV energies. Methods. We observed the SNR G106.3+2.7 using the MAGIC telescopes for 121.7 h in total - after quality cuts - between May 2017 and August 2019. The analysis energy threshold is ∼0.2 TeV, and the angular resolution is 0.07-0.1. We examined the γ-ray spectra of different parts of the emission, whilst benefitting from the unprecedented statistics and angular resolution at these energies provided by our new data. We also used measurements at other wavelengths such as radio, X-rays, GeV γ-rays, and 10 TeV γ-rays to model the emission mechanism precisely. Results. We detect extended γ-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detect a significant γ-ray emission with energies above 6.0 TeV from only the tail region suggests that the emissions above 10 TeV detected with air shower experiments (Milagro, HAWC, Tibet ASγ and LHAASO) are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of ∼1 PeV for that region. Such high-energy emission in this middle-aged SNR (4-10 kyr) can be explained by considering a scenario where protons escaping from the SNR in the past interact with surrounding dense gases at present. Conclusions. The γ-ray emission region detected with the MAGIC telescopes in the SNR G106.3+2.7 is extended and spatially coincident with the radio continuum morphology. The multi-wavelength spectrum of the emission from the tail region suggests proton acceleration up to ∼PeV, while the emission mechanism of the head region could either be hadronic or leptonic

    MAGIC observations provide compelling evidence of the hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7

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    The SNR G106.3+2.7, detected at 1--100 TeV energies by different γ\gamma-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape which can be divided into a head and a tail region with different physical conditions. However, it is not identified in which region the 100 TeV emission is produced due to the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear whether the origin of the γ\gamma-ray emission is leptonic or hadronic. With the better angular resolution provided by these new MAGIC data compared to earlier γ\gamma-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1^\circ resolution at TeV energies. We detected extended γ\gamma-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detected a significant γ\gamma-ray emission with energies above 6.0 TeV from the tail region only suggests that the emissions above 10 TeV, detected with air shower experiments (Milagro, HAWC, Tibet ASγ\gamma and LHAASO), are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of 1\sim 1 PeV for the tail region. Such a high energy emission in this middle-aged SNR (4--10 kyr) can be explained by considering the scenario that protons escaping from the SNR in the past interact with surrounding dense gases at present.Comment: 13 pages, 7 figures, Accepted for publication in A&

    Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514

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    The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy νsynch,p\nu_{synch,p} above 1keV). While those extreme states were so far observed only during high flux levels, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to VHE performed so far, focusing on a systematic characterisation of the intermittent extreme states. While our results confirm that 1ES 2344+514 typically exhibits νsynch,p>\nu_{synch,p}>1keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase of the electron acceleration efficiency without a change in the electron injection luminosity. We also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of νsynch,p\nu_{synch,p}. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. During a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions contribute significantly to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3-2keV band. Using a time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model.Comment: Accepted for publication in Astronomy & Astrophysic

    Multi-messenger characterization of Mrk 501 during historically low X-ray and γ\gamma-ray activity

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    We study the broadband emission of Mrk 501 using multi-wavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wavebands, with the highest occurring at X-rays and very-high-energy (VHE) γ\gamma-rays. A significant correlation (>>3σ\sigma) between X-rays and VHE γ\gamma-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between Swift-XRT and Fermi-LAT. We additionally find correlations between high-energy γ\gamma-rays and radio, with the radio lagging by more than 100 days, placing the γ\gamma-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE γ\gamma-rays from mid-2017 to mid-2019 with a stable VHE flux (>>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2-year-long low-state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED towards the low-state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock.Comment: 56 pages, 30 figures, 14 tables, submitted. Corresponding authors are L. Heckmann, D. Paneque, S. Gasparyan, M. Cerruti, and N. Sahakya

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

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    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

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    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field
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