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- 2026-07-15
Item type: Publicación , listelement.badge.specific-type Artículo de revista , The Powerful Shocks in RS Oph: NuSTAR X-Ray Data and a Complete ReviewOrio, Marina; Luna, G. J. M.; Behar, Ehud; Diesing, Rebecca; Gallagher, Jay; Mikolajewska, Joanna; Ness, Jan-UweAbstract: In the 2021 outburst of RS Ophiuchi, the gamma-ray and the X-ray flux were measured quasi-simultaneously from day 1 after the optical peak, offering the first comprehensive view of shocks in a nova occurring in a symbiotic system. We present a previously unpublished observation done with NuSTAR in the 3–79 keV range, 9 days after maximum, and we review the complex history of the evidence of shocks in the previous outbursts of this nova in light of the intensive X-ray monitoring of 2021. We find evidence that the shock causing the particle acceleration measured with the Cherenkov telescopes also produced the thermal flux detected in the 0.2–30 keV X-ray range, while the large gamma-ray flux observed with Fermi after about a day is not consistent with the X-ray observations. We conclude that an initial, strong shock, with a particle–particle loss timescale shorter than the timescale of particle acceleration at energy higher than a few GeV, occurred close to the red giant atmosphere, where either the X-rays’ emitting volume was reduced by turbulence, or—perhaps less likely—the X-rays were completely absorbed by large column density near the giant and by the accretion wake along the line of sight. We compare RS Oph with other novae in long-period systems with evolved companions, discussing how the shocks’ phenomenology is a powerful tool to derive other physical parameters. Finally, we discuss predictions that in T CrB, expected to have a new nova outburst within the next few years, the shocks may not be as energetic as in RS Oph. - 2026-07-30
Item type: Publicación , listelement.badge.specific-type Artículo de revista , A very rapidly rotating white dwarf in nova YZ ReticuliLuna, Gerardo Juan Manuel; Rawat, N.; Angeloni, R.; Orio, M.; Scaringi, S.; Dobrotka, A.; Magdolen, J.YZ Ret (Nova Reticuli 2020) is the first VY Scl-type nova-like variable observed to have undergone a classical nova eruption. Following the outburst, a timing analysis of 20-s cadence TESS data revealed a periodicity at approximately 42 s, suggesting its plausible classification as a fast-spinning intermediate polar (IP). To definitively identify the nature of this modulation, we performed a multi-instrument timing analysis using high-speed ground-based photometry Zorro/Gemini South (1 s cadence) and the South African Astronomical Observatory (5 s cadence) alongside TESS Sector 97 observations. Our ground-based data reveal a highly coherent period of 37.69131 ± 0.00001 s, which we identified as the true rotation period of the white dwarf. We demonstrate that the apparent 42.61 s signal in the TESS data is a Nyquist alias of this fundamental frequency. Furthermore, the signal amplitude in the TESS data is suppressed by a factor of ≈0.6 relative to the Gemini observations, a result that is consistent with the theoretical sinc-function damping expected for a 20-s integration time. The extreme coherence and long-term stability of the 37.69131 s signal rule out transient phenomena such as dwarf nova oscillations or non-radial pulsations. We conclude that YZ Ret hosts a fast-spinning magnetic white dwarf in an IP configuration. This discovery implies that mass loss during the nova eruption was likely driven by a fast magnetic rotator wind and provides a physical explanation for the missing supersoft X-ray phase, suggesting that nearly the entire accreted envelope was exhausted, promptly quenching the process of nuclear burning. - 2026-06-01
Item type: Publicación , listelement.badge.specific-type Artículo de revista , Las críticas de Johann Georg Hamann al movimiento de Ilustración y a las nociones kantianas de razón, emancipación y libertadQuiroz, David E.El presente artículo aborda las diferencias del pensamiento de Hamann con las ideas de la Ilustración alemana. Particularmente, mencionaremos las críticas a Kant acerca de la noción de razón pura y especialmente sobre los conceptos de libertad, emancipación y usos de la razón. El propósito es observar la importancia de tales cuestionamientos, considerando que el propio Hamann formó parte del movimiento, pero a la vez logró ser un crítico de su tiempo y de las ideas de sus contemporáneos. - 2026-04-29
Item type: Publicación , listelement.badge.specific-type Artículo de revista , Synthesis and characterization of carbon dots derived from spinach, green tea, and yerba mate for photodynamic therapyVega, Daniela Maza; Cacciari, R. Daniel; Lillo, Cristian; Sosa, Ayelen M.; Cardinal, M. Fernanda; Tuninetti, Jimena; Alonso, Silvia del Valle; Prieto, María Jimena; Martinez, Carolina Soledad; Gonzalez, Mónica C.; Alvira, Fernando; Caregnato, Paula; Montanari, JorgeAbstract: Photodynamic Therapy is a directed and minimally invasive treatment modality that requires efficient and biocompatible photosensitizers. In this work, we develop a green nanomedicine platform by synthesizing Carbon Dots (CDs) using a solvothermal method from extracts of three commercially available and carbon-rich sources: spinach, green tea, and yerba mate. This approach leverages the sustainability of the starting materials and highlights the versatility of carbon-based hybrid systems while evaluating their theranostic functionality and capability as Photodynamic Therapy (PDT) therapeutic effectors. The synthesized CDs were rigorously characterized by Dynamic Light Scattering, Zeta Potential, High-Resolution Transmission Electron Microscopy, Fourier-Transform Infrared Spectroscopy, 1H-Nuclear Magnetic Resonance Spectroscopy, Raman Spectroscopy, and Thermogravimetric Analysis. We found CDs populations with surface compositions rich in carboxyl, hydroxyl, and nitrogen-containing pyrrolic and pyridinic groups that contribute to their potential as nanoeffectors. We comprehensively evaluated the photogeneration of reactive oxygen species (ROS) through oxygen consumption kinetics and hydrogen peroxide quantification, identifying a clear predominance of Type I photosensitization mechanisms. A significant singlet oxygen quantum yield of nearly 29% was obtained for spinach-derived CDs when irradiating at 355 nm, supported by their characteristic chlorophyll-like absorption at 675 nm. Additionally, antioxidant capacity assays demonstrated that green tea and yerba mate derivatives retain high antioxidant properties, contrasting with the superior photosensitizing performance of spinach. Finally, light-exposed viability assays on HaCaT and 3T3 cell lines demonstrated significant photodynamic activity and established that spinach-derived particles are the most biocompatible, maintaining cell viability at 100 µg per ml. These results demonstrate the potential of these plant-derived CDs for targeted and non-invasive therapy applications against cancer cells or parasites. This study provides a sustainable and biocompatible approach for delivering photodynamic therapy agents. By balancing radiative and non-radiative electronic pathways, these plant-derived CDs offer a promising alternative. - 2026-06-01
Item type: Publicación , listelement.badge.specific-type Artículo de revista , Entre la enumeración caótica y la teoría de las affordances literariasMosquera, Mariano ErnestoEn el siguiente trabajo partimos de los esfuerzos críticos de Leo Spitzer sobre la enumeración caótica para discutir uno de sus presupuestos metodológicos: la neutralidad de la forma. Para ello, realizaremos una importación teórica de la psicología ambiental: el concepto de affordance. Esta categoría nos permitirá adentrarnos en proyectos teóricos literarios que ya han utilizado tal concepto, para evaluarlos. Finalmente, utilizaremos un concepto relacionalista y material de las affordances para resignificar nuevas lecturas clásicas de la literatura, incluida, hacia el final, la enumeración caótica. - 2026-08-22
Item type: Publicación , listelement.badge.specific-type Artículo de revista , A micronova burst in the intermediate polar IGR J17014-4306Oliveira, Alexandre S; Souza, D C; Luna, G J M; Rodrigues, C VAbstract: We report the detection of a short optical burst in TESS data of IGR J17014-4306, the eclipsing intermediate polar with the longest known orbital period. The burst lasts 1.56 d and shows multiple peaks, reaching (9.3 ± 0.2) × 1033 erg s−1, and releases a total energy of (3.25 ± 0.01) × 1038 erg. The burst parameters are consistent with those of a micronova eruption, currently understood as a thermonuclear runaway in the magnetically-confined accretion column. From its energy, we infer a burned column mass of ∼1.6 × 10−11 M⊙ which, under several assumptions, suggests a recurrence time of ∼20 d. Our search for similar events in long-term Gaia, ASAS-SN, and AAVSO light curves reveals 16 possible fast brightenings over ∼11 yr, suggesting that micronova events may be frequent in IGR J17014-4306. Timing analysis of the TESS data shows that the white-dwarf spin signal remains stable before and after the burst, but is not clearly detectable during the eruption. Its extreme orbital period and eclipsing nature make IGR J17014-4306 an ideal test-bed for further studies of magnetically confined thermonuclear burning on white dwarfs. - 2026-02-27
Item type: Publicación , listelement.badge.specific-type Artículo de revista , Evolution of the recent high-accretion state of the recurrent nova T CrB: HST, Swift, NuSTAR, and XMM-Newton observationsLuna, G. J. M.; Kuin, N. P. M.; Mukai, K.; Sokoloski, J. L.; Page, K.; Osborne, J. P.As the recurrent nova T Coronae Borealis (T CrB) approaches its next predicted thermonuclear eruption, it is currently exhibiting a “super-active state” (SAS) characterized by enhanced multiwavelength emission similar to the behavior recorded prior to the 1946 outburst. We present a multiwavelength analysis of the SAS and the subsequent “faint state” using observations from HST, Swift, NuSTAR, and XMM-Newton. Our results indicate that the SAS was driven by an increase in the mass accretion rate, which caused the accretion disk’s boundary layer to become optically thick. A weighted least squares regression analysis quantifies the evolution of the accretion components, displaying a highly significant (4.5 σ) increase in the luminosity of the optically thin cooling flow (L cf) and a marginal (2.58 σ) decrease in the optically thick boundary layer luminosity (L bb) as the system transitioned into the faint state. We find that this dimming is consistent with an intrinsic change in the accretion flow rather than dust obscuration, supported by the lack of infrared excess and the stability of the 2175 Å feature. Additionally, a time-series analysis using autoregressive modeling to account for correlated red noise revealed no significant periodicities, thereby disputing the previously reported ∼6000 s signal. These findings suggest that the pre-outburst evolution of T CrB is characterized by significant changes in the accretion disk structure and boundary layer, providing a self-consistent physical framework for the system’s behavior as it approaches eruption. - 2026-04-08
Item type: Publicación , listelement.badge.specific-type Artículo de revista , Aprendizajes, habilidades emergentes y mediación tecnológica en la pandemia y en la postpandemia. Reconstrucciones a partir de las voces de diferentes actores en el marco de una investigación en redWeber, Verónica; Lion, Carina; Palladino, CeciliaEl artículo sistematiza resultados de una investigación en red en el marco de PICTO redes “Las reconfiguraciones emergentes de las prácticas de enseñanza universitaria ‘atravesadas por las tecnologías. Estudio multidimensional en siete regiones de Argentina”. Hace foco en la mediación tecnológica y los aprendizajes que emergieron durante la pandemia y en la postpandemia. A partir de la interpretación cualitativa de los datos derivados de entrevistas en profundidad a autoridades, docentes y estudiantes de diferentes universidades nacionales argentinas, se abordan las habilidades de autonomía, autorregulación y la colaboración como habilidades sustantivas en los procesos de aprendizaje durante la pandemia. Se analiza el valor de las experiencias, los lazos intersubjetivos y la vinculación con el oficio y las prácticas profesionales como dimensiones que andamiaron los aprendizajes durante la pandemia y se interroga acerca de la reconstrucción de dichas dimensiones y habilidades en la postpandemia desde la mirada crítica de los distintos actores institucionales. ¿Cómo se concibieron los aprendizajes desde la perspectiva de los/as docentes y estudiantes en la pandemia? ¿Se transformaron las prácticas evaluativas en relación con estas concepciones? ¿Qué experiencias distintivas tuvieron lugar en la pandemia? ¿Qué nuevos interrogantes se formularon en torno de los aprendizajes en la postpandemia?