Nueva vía de generación de radicales aniones derivados de 1,2,5-tiadiazol 1, 1-dióxidos

En la actualidad hay un creciente interés en el estudio de compuestos orgánicos aceptores de electrones capaces de acumular o transportar carga eléctrica, aplicables en semiconductores, imanes orgánicos, etc. Sin embargo, la mayoría de éstos tienen la desventaja de ser sensibles al aire y a la humedad y/o son estables únicamente a bajas temperaturas. Este trabajo presenta los resultados obtenidos en la acumulación de radicales aniones (ARs.-) derivados de 1,2,5-tiadiazol 1,1-dióxido (TDZ) 3,4-disustituido con un sistema electrónico-? conjugado y extendido.El estudio del comportamiento voltamperométrico cíclico (VC), mostró que TPYR y TRojo [3,4] son electroactivos a potenciales catódicos EpcI ca. -0,5 V (vs Ag0/Ag+). Este pico de reducción corresponde al primer proceso de transferencia de carga  (TPYR + e- ? TPYR.-). A menor potencial se observa una nueva etapa de reducción, EpcII ca. -1,2 V (vs Ag+/Ag0), correspondiente al proceso TPYR.- + e- ? TPYR=.  Estos resultados evidenciaron la capacidad que poseen TPYRy TROJO para formar ARs.- estables en solución de solventes apróticos secos.Se prepararon TPYR.-y TROJO.- por reducción química con LiCN y electrólisis a potencial controlado (EPC, Eapl ca. -0,7 V vs Ag0/Ag+) de TPYR y TROJO en solución de solventes apróticos. Los rendimientos molares de TPYR.-y TROJO.- preparados por ambos procedimientos se estimaron por VC según el método descrito por Dermortier et al [5]. Los rendimientos para ambos ARs.- fueron buenos. Los ARs.-se caracterizaron por VC, UV-Vis y espectroscopía de resonancia paramagnética (EPR). Estas técnicas permitieron evidenciar la formación de los ARs.- como su estabilidad frente al agua y el oxígeno. Se observó que los TDZ en solución de solventes apróticos presentaron un inusual comportamiento frente a la luz. Se inició el estudio del comportamiento fotoquímico y se enfocó hacia la búsqueda de una nueva vía de obtención de ARs.-  derivados de TDZ.Los espectros UV-Vis y de fluorescencia de TDZs  permitieron elegir condiciones adecuadas de irradiación a las diferentes longitudes de onda (?) de emision (254, 300, 350 y 200-800 nm). Las fotólisis se monitorearon en el tiempo y los ARs.- se caracterizaron por UV-Vis, VC y EPR. Se observó un efecto de la naturaleza del solvente. TDZs en solución de DMF, DCM, ACN, y DMSO por irradiación con luz de 300 y 350 nm descompònen sin generar ARs.-. TDZs en solución de DMSO, DCM y ACN  presentan un comportamiento similar al ser irradiados con lámparas de 254 y 200-800 nm. Sin embargo, TDZs forman ARs.- al ser irradiados con lámparas de 254 y 200-800 nm en solución de DMF. Las fotólisis realizadas con una lámpara policromática (200-800 nm) dieron mayor rendimiento de RAs.-.Facultad de Ciencias Exacta

Nueva vía de generación de radicales aniones derivados de 1,2,5-tiadiazol 1, 1-dióxidos

En la actualidad hay un creciente interés en el estudio de compuestos orgánicos aceptores de electrones capaces de acumular o transportar carga eléctrica, aplicables en semiconductores, imanes orgánicos, etc. Sin embargo, la mayoría de éstos tienen la desventaja de ser sensibles al aire y a la humedad y/o son estables únicamente a bajas temperaturas. Este trabajo presenta los resultados obtenidos en la acumulación de radicales aniones (ARs.-) derivados de 1,2,5-tiadiazol 1,1-dióxido (TDZ) 3,4-disustituido con un sistema electrónico-? conjugado y extendido.El estudio del comportamiento voltamperométrico cíclico (VC), mostró que TPYR y TRojo [3,4] son electroactivos a potenciales catódicos EpcI ca. -0,5 V (vs Ag0/Ag+). Este pico de reducción corresponde al primer proceso de transferencia de carga  (TPYR + e- ? TPYR.-). A menor potencial se observa una nueva etapa de reducción, EpcII ca. -1,2 V (vs Ag+/Ag0), correspondiente al proceso TPYR.- + e- ? TPYR=.  Estos resultados evidenciaron la capacidad que poseen TPYRy TROJO para formar ARs.- estables en solución de solventes apróticos secos.Se prepararon TPYR.-y TROJO.- por reducción química con LiCN y electrólisis a potencial controlado (EPC, Eapl ca. -0,7 V vs Ag0/Ag+) de TPYR y TROJO en solución de solventes apróticos. Los rendimientos molares de TPYR.-y TROJO.- preparados por ambos procedimientos se estimaron por VC según el método descrito por Dermortier et al [5]. Los rendimientos para ambos ARs.- fueron buenos. Los ARs.-se caracterizaron por VC, UV-Vis y espectroscopía de resonancia paramagnética (EPR). Estas técnicas permitieron evidenciar la formación de los ARs.- como su estabilidad frente al agua y el oxígeno. Se observó que los TDZ en solución de solventes apróticos presentaron un inusual comportamiento frente a la luz. Se inició el estudio del comportamiento fotoquímico y se enfocó hacia la búsqueda de una nueva vía de obtención de ARs.-  derivados de TDZ.Los espectros UV-Vis y de fluorescencia de TDZs  permitieron elegir condiciones adecuadas de irradiación a las diferentes longitudes de onda (?) de emision (254, 300, 350 y 200-800 nm). Las fotólisis se monitorearon en el tiempo y los ARs.- se caracterizaron por UV-Vis, VC y EPR. Se observó un efecto de la naturaleza del solvente. TDZs en solución de DMF, DCM, ACN, y DMSO por irradiación con luz de 300 y 350 nm descompònen sin generar ARs.-. TDZs en solución de DMSO, DCM y ACN  presentan un comportamiento similar al ser irradiados con lámparas de 254 y 200-800 nm. Sin embargo, TDZs forman ARs.- al ser irradiados con lámparas de 254 y 200-800 nm en solución de DMF. Las fotólisis realizadas con una lámpara policromática (200-800 nm) dieron mayor rendimiento de RAs.-.Facultad de Ciencias Exacta

Relatively Low HIV Infection Rates in Rural Uganda, but with High Potential for a Rise: A Cohort Study in Kayunga District, Uganda

BACKGROUND: Few studies have been conducted in Uganda to identify and quantify the determinants of HIV-1 infection. We report results from a community-based cohort study, whose primary objectives were to determine HIV-1 prevalence, incidence, and determinants of these infections, among other objectives. METHODOLOGY: Consenting volunteers from the rural district of Kayunga in Uganda aged 15-49 years were enrolled between March and July 2006. Participants were evaluated every six months. A questionnaire that collected information on behavioral and other HIV-1 risk factors was administered, and a blood sample obtained for laboratory analysis at each study visit. PRINCIPAL FINDINGS: HIV-1 prevalence among the 2025 participants was 9.9% (95% CI = 8.6%-11.2%). By the end of 12 months of follow-up, 1689.7 person-years had been accumulated, with a median follow-up time of 11.97 months. Thirteen HIV-1 incident cases were detected giving an annual HIV-1 incidence of 0.77% (95% CI = 0.35-1.19). Prevalence of HSV-2 infection was 57% and was strongly associated with prevalent HIV-1 infection (adjusted Odds Ratio = 3.9, 95% CI = 2.50-6.17); as well as incident HIV-1 infection (adjusted Rate Ratio (RR) = 8.7, 95% CI = 1.11-67.2). The single most important behavioral characteristic associated with incident HIV infection was the number of times in the past 6 months, a participant had sex with person(s) they suspected/knew were having sex with others; attaining statistical significance at 10 times and higher (adjusted RR = 6.3, 95% CI = 1.73-23.1). By the end of 12 months of follow-up, 259 participants (13%) were lost to follow-up, 13 (0.6%) had died, and 2 (0.1%) had withdrawn consent. CONCLUSIONS: Despite relatively low HIV-1 incidence observed in this community, prevalence remains relatively high. In the presence of high prevalence of HSV-2 infection and the behavioral characteristic of having sex with more than one partner, there is potential for increase in HIV-1 incidence

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Constraints on the cosmic expansion history from GWTC-3

We use 47 gravitational-wave sources from the Third LIGO-Virgo-KAGRA Gravitational-Wave Transient Catalog (GWTC-3) to estimate the Hubble parameter $H(z)$, including its current value, the Hubble constant $H_0$. Each gravitational-wave (GW) signal provides the luminosity distance to the source and we estimate the corresponding redshift using two methods: the redshifted masses and a galaxy catalog. Using the binary black hole (BBH) redshifted masses, we simultaneously infer the source mass distribution and $H(z)$. The source mass distribution displays a peak around $34\, {\rm M_\odot}$, followed by a drop-off. Assuming this mass scale does not evolve with redshift results in a $H(z)$ measurement, yielding $H_0=68^{+12}_{-7} {\rm km\,s^{-1}\,Mpc^{-1}}$ ($68\%$ credible interval) when combined with the $H_0$ measurement from GW170817 and its electromagnetic counterpart. This represents an improvement of 17% with respect to the $H_0$ estimate from GWTC-1. The second method associates each GW event with its probable host galaxy in the catalog GLADE+, statistically marginalizing over the redshifts of each event's potential hosts. Assuming a fixed BBH population, we estimate a value of $H_0=68^{+8}_{-6} {\rm km\,s^{-1}\,Mpc^{-1}}$ with the galaxy catalog method, an improvement of 42% with respect to our GWTC-1 result and 20% with respect to recent $H_0$ studies using GWTC-2 events. However, we show that this result is strongly impacted by assumptions about the BBH source mass distribution; the only event which is not strongly impacted by such assumptions (and is thus informative about $H_0$) is the well-localized event GW190814

Effects of alirocumab on types of myocardial infarction: insights from the ODYSSEY OUTCOMES trial

Aims  The third Universal Definition of Myocardial Infarction (MI) Task Force classified MIs into five types: Type 1, spontaneous; Type 2, related to oxygen supply/demand imbalance; Type 3, fatal without ascertainment of cardiac biomarkers; Type 4, related to percutaneous coronary intervention; and Type 5, related to coronary artery bypass surgery. Low-density lipoprotein cholesterol (LDL-C) reduction with statins and proprotein convertase subtilisin–kexin Type 9 (PCSK9) inhibitors reduces risk of MI, but less is known about effects on types of MI. ODYSSEY OUTCOMES compared the PCSK9 inhibitor alirocumab with placebo in 18 924 patients with recent acute coronary syndrome (ACS) and elevated LDL-C (≥1.8 mmol/L) despite intensive statin therapy. In a pre-specified analysis, we assessed the effects of alirocumab on types of MI. Methods and results  Median follow-up was 2.8 years. Myocardial infarction types were prospectively adjudicated and classified. Of 1860 total MIs, 1223 (65.8%) were adjudicated as Type 1, 386 (20.8%) as Type 2, and 244 (13.1%) as Type 4. Few events were Type 3 (n = 2) or Type 5 (n = 5). Alirocumab reduced first MIs [hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.77–0.95; P = 0.003], with reductions in both Type 1 (HR 0.87, 95% CI 0.77–0.99; P = 0.032) and Type 2 (0.77, 0.61–0.97; P = 0.025), but not Type 4 MI. Conclusion  After ACS, alirocumab added to intensive statin therapy favourably impacted on Type 1 and 2 MIs. The data indicate for the first time that a lipid-lowering therapy can attenuate the risk of Type 2 MI. Low-density lipoprotein cholesterol reduction below levels achievable with statins is an effective preventive strategy for both MI types.For complete list of authors see http://dx.doi.org/10.1093/eurheartj/ehz299</p

Diving below the spin-down limit:constraints on gravitational waves from the energetic young pulsar PSR J0537-6910

We present a search for continuous gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537-6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using NICER data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537-6910 has the largest spin-down luminosity of any pulsar and is highly active with regards to glitches. Analyses of its long-term and inter-glitch braking indices provided intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a time-varying mass quadrupole moment. Its 62 Hz rotation frequency also puts its possible gravitational-wave emission in the most sensitive band of LIGO/Virgo detectors. Motivated by these considerations, we search for gravitational-wave emission at both once and twice the rotation frequency. We find no signal, however, and report our upper limits. Assuming a rigidly rotating triaxial star, our constraints reach below the gravitational-wave spin-down limit for this star for the first time by more than a factor of two and limit gravitational waves from the l = m = 2 mode to account for less than 14% of the spin-down energy budget. The fiducial equatorial ellipticity is limited to less than about 3 x 10⁻⁵, which is the third best constraint for any young pulsar

Search for anisotropic gravitational-wave backgrounds using data from Advanced LIGO and Advanced Virgo's first three observing runs

We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we include Virgo data in our analysis and run our search with a new efficient pipeline called {\tt PyStoch} on data folded over one sidereal day. We use gravitational-wave radiometry (broadband and narrow band) to produce sky maps of stochastic gravitational-wave backgrounds and to search for gravitational waves from point sources. A spherical harmonic decomposition method is employed to look for gravitational-wave emission from spatially-extended sources. Neither technique found evidence of gravitational-wave signals. Hence we derive 95\% confidence-level upper limit sky maps on the gravitational-wave energy flux from broadband point sources, ranging from $F_{\alpha, \Theta} < {\rm (0.013 - 7.6)} \times 10^{-8} {\rm erg \, cm^{-2} \, s^{-1} \, Hz^{-1}},$ and on the (normalized) gravitational-wave energy density spectrum from extended sources, ranging from $\Omega_{\alpha, \Theta} < {\rm (0.57 - 9.3)} \times 10^{-9} \, {\rm sr^{-1}}$, depending on direction ($\Theta$) and spectral index ($\alpha$). These limits improve upon previous limits by factors of $2.9 - 3.5$. We also set 95\% confidence level upper limits on the frequency-dependent strain amplitudes of quasimonochromatic gravitational waves coming from three interesting targets, Scorpius X-1, SN 1987A and the Galactic Center, with best upper limits range from $h_0 < {\rm (1.7-2.1)} \times 10^{-25},$ a factor of $\geq 2.0$ improvement compared to previous stochastic radiometer searches.Comment: 23 Pages, 9 Figure