Existence of weak-renormalized solution for a nonlinear system

We prove an existence result for a coupled system of the reactiondiffusion kind. The fact that no growth condition is assumed on some nonlinear terms motivates the search of a weak-renormalized solution.We prove an existence result for a coupled system of the reactiondiffusion kind. The fact that no growth condition is assumed on some nonlinear terms motivates the search of a weak-renormalized solution

ALGUNAS APLICACIONES DE LA TEORÃA DE SISTEMAS AL DESARROLLO ORGANIZACIONAL

In the routine of daily activities, and the eagerness to obtain quantitative results, organizations run the risk of becoming absorbed in reductionist notions concerning their task environments (internal and external). This position has counterproductive effects on the learning and renovation capacities of the own organizations, reducing their success and permanence possibilities. The properties and tools of the systemic approach provide information about relevant issues and problems that, in countless cases, are unnoticed by administration and management schemes of rationalist character. Different arguments holding this thesis are exposed through the analysis of several topics and examples.Holism, organizational development, organizational learning, strategic planning, systemic thinking, systems theory, task environment., Agribusiness,

An Analysis of the Evolution Equations for a Generalized Bioconvective Flow

We prove results on existence and uniqueness of solutions of a system of equations modeling the evolution of a generalized bioconvective flow. The mathematical model considered in the present work describes the convective motion generated by the upward swimming of a culture of microorganisms under the influence of vertical gravitational forces, in an incompressible viscous fluid whose viscosity may depend on the concentration of microorganisms

In vivo chromatin targets of the transcription factor Yin Yang 2 in trophoblast stem cells

Background: Yin Yang 2 (YY2) is a zinc finger protein closely related to the well-characterized Yin Yang 1 (YY1). YY1 is a DNA-binding transcription factor, with defined functions in multiple developmental processes, such as implantation, cell differentiation, X inactivation, imprinting and organogenesis. Yy2 has been treated as a largely immaterial duplication of Yy1, as they share high homology in the Zinc Finger-region and similar if not identical in vitro binding sites. In contrast to these similarities, gene expression alterations in HeLa cells with attenuated levels of either Yy1 or Yy2 were to some extent gene-specific. Moreover, the chromatin binding sites for YY2, except for its association with transposable retroviral elements (RE) and Endogenous Retroviral Elements (ERVs), remain to be identified. As a first step towards defining potential Yy2 functions matching or complementary to Yy1, we considered in vivo DNA binding sites of YY2 in trophoblast stem (TS) cells. Results: We report the presence of YY2 protein in mouse-derived embryonic stem (ES) and TS cell lines. Following up on our previous report on ERV binding by YY2 in TS cells, we investigated the tissue-specificity of REX1 and YY2 binding and confirm binding to RE/ERV targets in both ES cells and TS cells. Because of the higher levels of expression, we chose TS cells to understand the role of Yy2 in gene and chromatin regulation. We used in vivo YY2 association as a measure to identify potential target genes. Sequencing of chromatin obtained in chromatin-immunoprecipitation (ChIP) assays carried out with aYY2 serum allowed us to identify a limited number of chromatin targets for YY2. Some putative binding sites were validated in regular ChIP assays and gene expression of genes nearby was altered in the absence of Yy2. Conclusions: YY2 binding to ERVs is not confined to TS cells. In vivo binding sites share the presence of a consensus binding motif. Selected sites were uniquely bound by YY2 as opposed to YY1, suggesting that YY2 exerts unique contributions to gene regulation. YY2 binding was not generally associated with gene promoters. However, several YY2 binding sites are linked to long noncoding RNA (lncRNA) genes and we show that the expression levels of a few of those are Yy2-dependent

Evidence of a radiation belt around a brown dwarf

Radio observations of ultracool dwarfs, objects comprising brown dwarfs and the very lowest mass stars, have mainly focused on analyzing their light-curve and spectral energy distributions providing valuable insights into their magnetic fields. However, spatially-resolved studies of such magnetospheres have been elusive so far. Radio interferometric observations of the brown dwarf LSR J1835+3259 reveal an extended magnetosphere with a morphology compatible with the presence of a radiation belt, similar to that of Jupiter and Earth, consisting of energetic particles confined via magnetic mirroring. Our finding suggests that radio emitting ultracool dwarfs may behave as scaled up versions of Jupiter, validating the connection between dipole-ordered magnetic fields and the presence of belt-like morphologies and aurorae beyond our Solar System.Comment: Submitted on 12 January 2023 to Science. In revie

82: Severe Hemorrhagic Cystitis (HC) After Allogeneic Hematopoeitic Stem Cell Transplantation (HSCT): Incidence and Risk Factors

With the purpose to investigate the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92$-$125723.9 (hereafter VHS 1256$-$1257); this system is composed by an equal-mass M7.5 binary and a L7 low-mass substellar object located at only 15.8\,pc. We observed in phase-reference mode the system VHS 1256$-$1257 with the Karl G. Jansky Very Large Array at $X$- and $L$- band and with the European VLBI Network at $L$-band in several epochs during 2015 and 2016. We discovered radio emission at $X$-band spatially coincident with the equal-mass M7.5 binary with a flux density of 60 $\mu$Jy. We determined a spectral index $\alpha = -1.1 \pm 0.3$ between 8 and 12 GHz, suggesting that non-thermal, optically-thin, synchrotron or gyrosynchrotron radiation is responsible for the observed radio emission. Interestingly, no signal is seen at $L$-band where we set a 3-$\sigma$ upper limit of 20 $\mu$Jy. This might be explained by strong variability of the binary or self-absorption at this frequency. By adopting the latter scenario and gyrosynchrotron radiation, we constrain the turnover frequency to be in the interval 5--8.5 GHz, from which we infer the presence of kG-intense magnetic fields in the M7.5 binary. Our data impose a 3-$\sigma$ upper bound to the radio flux density of the L7 object of 9 $\mu$Jy at 10\,GHz.Comment: 6 pages, 4 figures. Accepted for publication in A&

Photoisomerization Efficiency of a Solar Thermal Fuel in the Strong Coupling Regime

Strong exciton-photon coupling is achieved when the interaction between molecules and an electromagnetic field is increased to a level where they cannot be treated as separate systems. This leads to the formation of polaritonic states and an effective rearrangement of the potential energy surfaces, which opens the possibility to modify photochemical reactions. This work investigates how the strong coupling regime is affecting the photoisomerization efficiency and thermal backconversion of a norbornadiene–quadricyclane molecular photoswitch. The quantum yield of photoisomerization shows both an excitation wavelength and exciton/photon constitution dependence. The polariton-induced decay and energy transfer processes are discussed to be the reason for this finding. Furthermore, the thermal back conversion of the system is unperturbed and the lower polariton effectively shifts the absorption onset to lower energies. The reason for the unperturbed thermal backconversion is that it occurs on the ground state, which is unaffected. This work demonstrates how strong coupling can change material properties towards higher efficiencies in applications. Importantly, the experiments illustrate that strong coupling can be used to optimize the absorption onset of the molecular photoswitch norbonadiene without affecting the back reaction from the uncoupled quadricyclane

Radiation-Induced Leiomyosarcoma after Breast Cancer Treatment and TRAM Flap Reconstruction

The development of a radiation-induced sarcoma (RIS) in the post mastectomy thoracic treatment volume is an infrequent, but recognized, event. Its frequency is rising in relation with increasing survival of breast cancer patients treated with adjuvant radiation therapy, and is associated with poor prognosis despite treatment. We present a case of leiomyosarcoma in a patient who underwent mastectomy followed by radiotherapy for invasive ductal carcinoma. A delayed TRAM flap reconstruction was performed 10 years after and a rapid growing mass under the reconstructed flap appeared, on routine follow-up, twenty years later. This report analyzes the diagnostic and therapeutic approach of patients with RIS

The milliarcsecond-scale radio structure of AB Dor A

Context: The fast rotator, pre-main sequence star AB Dor A is a strong and persistent radio emitter. The extraordinary coronal flaring activity is thought to be the origin of compact radio emission and other associated phenomena as large slingshot prominences. Aim: We aim to investigate the radio emission mechanism and the milliarcsecond radio structure around AB Dor A. Methods: We performed phase-referenced VLBI observations at 22.3 GHz, 8.4 GHz, and 1.4 GHz over more than one decade using the Australian VLBI array. Results: Our 8.4 GHz images show a double core-halo morphology, similar at all epochs, with emission extending at heights between 5 and 18 stellar radii. Furthermore, the sequence of the 8.4 GHz maps shows a clear variation of the source structure within the observing time. However, images at 1.4 GHz and 22.3 GHz are compatible with a compact source. The phase-reference position at 8.4 GHz and 1.4 GHz are coincident with those expected from the well-known milliarcsecond-precise astrometry of this star, meanwhile the 22.3 GHz position is 4$\sigma$ off the prediction in the north-west direction. The origin of this offset is still unclear. Conclusions: We have considered several models to explain the morphology and evolution of the inner radio structure detected in AB Dor A which include emission from the stellar polar caps, a flaring, magnetically-driven loop structure, and the presence of helmet streamers. A possible close companion to AB Dor A has been also investigated. Our results confirm the extraordinary coronal magnetic activity of this star, able to produce compact radio structures at very large heights, so far only seen in binary interacting systems.Comment: 11 pages, 6 figures, accepted for publication in Astronomy and Astrophysic