STUDY OF ANTARCTIC-SOUTH AMERICA CONNECTIVITY FROM IONOSPHERIC RADIO SOUNDINGS

Multi-instrument probing of the ionosphere at high latitudes is of great interest to improve our understanding of it, and because the processes originated in the interplanetary space print your signatures there. Nowadays, the ionosphere has been probed by many different radio techniques, from geodetic observations (GPS), passing by radar measurements up to the analysis of very low frequency (VLF) wave paths. The simultaneous and integrated observations have been provided the ability to study the ionosphere from high in the F-region to bottom of the D-layer, and also the coupling processes from the magnetosphere to the neutral atmosphere. The study of the Antarctic-South America connectivity is important to understand/characterize how the polar atmospheric variations can affect the lower latitudes, in which context, the instrument networks are essential. This paper presents the radio techniques that have been used at Comandante Ferraz Brazilian Station in Antarctica for probing the ionosphere, as well the instrumentation characteristics and in which network it is integrated. It also provides some recent scientific results obtained from the ionospheric soundings.ESTUDIO DE LA CONECTIVIDAD ANTÁRTIDA-SUDAMÉRICA A PARTIR DE RADIO SONDEOS DE LA IONÓSFERA. Sondeos multi-instrumento de la ionósfera, realizados a altas latitudes, son de gran interés para mejorar nuestro entendimiento de ésta y porque los procesos originados en el espacio interplanetario dejan su huella ahí. La ionósfera ha sido sondeada con diferentes técnicas de radio, desde observaciones geodésicas (GPS), medidas de radar, hasta el análisis de propagación de ondas de muy baja frecuencia (VLF). Las observaciones simultáneas e integradas han permitido estudiar la ionósfera desde la región F hasta la base de la capa D, así como los procesos de acoplamiento de la magnetósfera hasta la atmósfera neutra. El estudio de la conectividad Antártida-Sudamérica es importante para entender y caracterizar cómo las variaciones atmosféricas polares pueden afectar las bajas latitudes, y en qué contexto son esenciales las redes de intrumentos. El presente artículo presenta las técnicas de radiometría que han sido usadas para sondear la ionósfera en la estación antártica brasileña Comandante Ferraz y sobre territorio sudamericano, así como las características de la intrumentación y a cuáles redes ésta se encuentra integrada. Presentamos también algunos resultados de investigación obtenidos recientemente de estos sondeos. palabras clave: Ionósfera; radio-sondeo; Antártida; América del Sur.ESTUDO DA CONECTIVIDADE ANTÁRTICA-AMÉRICA DO SUL A PARTIR DE RÁDIO SONDAGENS DA IONOSFERA.  Sondagens da ionosfera feitas com múltiplos instrumentos, nas altas latitudes, são de grande interesse para ampliar nosso conhecimento sobre essa região, e porque lá os processos que se originam no espaço interplanetário deixam suas marcas. Atualmente a ionosfera tem sido monitorada por diferentes técnicas na faixa rádio, indo das observações de GPS, passando por medidas de radares até a análise de propagação de ondas de frequência muito baixa (VLF). As observações simultâneas e integradas tem permitido estudar a ionosfera desde o topo da região F até a base da região D, e também os processos de acoplamento desde a magnetosfera até a atmosfera neutra. O estudo da conectividade entre Antártica e América do Sul é importante para se entender/caracterizar como as variações atmosféricas que estão acontecendo nas regiões polares afetam as latitudes mais baixas, e em cujo contexto, as redes de instrumentos são essenciais. Este artigo apresenta as técnicas de rádio sondagens em uso na Estação Antártica Comandante Ferraz e na América do Sul para se estudar a ionosfera, bem como as características da instrumentação utilizada e em quais redes elas estão integradas. Apresentamos também alguns resultados de pesquisa recentemente obtidos destas sondagens.     palavras-chave: Ionosfera; sondagens rádio; Antártica; América do Sul

Characterization of GPS total electron content (GPS-TEC) in Antarctica from 2004 to 2011

The vertical total electron content (VTEC) obtained from 2004 to 2011 at Comandante Ferraz Brazilian Antarctic Station (62.1°S, 58.4°W) is analyzed to study the mean diurnal, seasonal and annual variations. The maximum daytime VTEC had an annual variation that decreased from 2004 to 2008, and then starting to increase in 2009, which followed the variation of the solar activity. The daily VTEC shows good linear correlation with solar radiation intensity, which is also dependent on the solar zenithal angle. The mean diurnal VTEC shows a semiannual variation, with larger peaks in equinoxes for all years; no winter anomaly was observed, and in summer, there was no clear diurnal variation. The semiannual variation of the VTEC is also modulated by solar activity, with larger VTEC peaks when the solar activity was higher.Facultad de Ciencias Astronómicas y Geofísica

Characterization of GPS total electron content (GPS-TEC) in Antarctica from 2004 to 2011

The vertical total electron content (VTEC) obtained from 2004 to 2011 at Comandante Ferraz Brazilian Antarctic Station (62.1°S, 58.4°W) is analyzed to study the mean diurnal, seasonal and annual variations. The maximum daytime VTEC had an annual variation that decreased from 2004 to 2008, and then starting to increase in 2009, which followed the variation of the solar activity. The daily VTEC shows good linear correlation with solar radiation intensity, which is also dependent on the solar zenithal angle. The mean diurnal VTEC shows a semiannual variation, with larger peaks in equinoxes for all years; no winter anomaly was observed, and in summer, there was no clear diurnal variation. The semiannual variation of the VTEC is also modulated by solar activity, with larger VTEC peaks when the solar activity was higher.Facultad de Ciencias Astronómicas y Geofísica

Installation and configuration of an ionospheric scintillation monitoring station based on GNSS SDR receivers in Brazil

The use of Global Navigation Satellite Systems (GNSSs) is nowadays very popular, and the positioning service that they provide is becoming the basis of several applications. Due to their wide coverage, GNSS signals can be used at no cost as probing signals to retrieve parameters to characterize the atmosphere, such as ionospheric scintillation indexes. GNSS receivers coupled to the specific algorithm are indeed a valid alternative to large and expensive ad hoc equipment such as ionosondes. In particular, Software Defined Radio (SDR) receivers are characterized by a higher level of flexibility and configurability when compared to commercial receivers, which fits for the purposes of ionospheric monitoring and enable the study of advanced and innovative algorithms, both for scientific purposes (ionospheric monitoring, space weather), and for technological development (robust GNSS receivers design). A GNSS-based ionosphere monitoring station, including an SDR-based receiver and a professional receiver, was installed in the CRAAM laboratory at Mackenzie Presbyterian University (São Paulo, Brazil) on May 2017. Details of the installation and the new approaches for the storage, processing, and transfer of GNSS data, including raw Intermediate Frequency (IF) samples, are described, along with preliminary results related to ionospheric events captured during the first months of its operation

Solar Submillimeter Telescope next generation

The Solar Submillimeter Telescope (SST) is an unique instrument that has been observing the Sun daily since 2001 bringing a wealth of information and raising new questions about the particle acceleration and transport, and emission mechanisms during flares. We are now designing its successor, the SSTng, that will expand the scientific goals of the instrument, including non-solar source observations.Comment: Accepted for the URSI GASS 2023, Sapporo, japan, 19-26 August 2023. 4 pages, 4 figure

Folic acid-mesoporous silicon nanoparticles enhance the anticancer activity of the p73-activating small molecule LEM2

Many drugs with anticancer potential fail in their translation to the clinics due to problems related to pharmacokinetics. LEM2 is a new dual inhibitor of MDM2/mutp53-TAp73 interactions with interesting in vitro anticancer activity, which opens new hopes as an unconventional anticancer therapeutic strategy against cancers lacking p53 or with impaired p53 pathways. As others xanthone derivatives, LEM2 has limited aqueous solubility, posing problems to pursue in vivo assays, and therefore limiting its potential clinical translation. In this work, a mesopomus silicon (PSi)-based nanodelivery system was developed with folate functionalization (APTES-TCPSi-PEG-FA) for targeted delivery, which successfully increased LEM2 solubility when compared to bulk LEM2, evidenced in payload release study. Such effect was reflected on the increase of LEM2 cytotoxicity in HCT116 and MDA-MB-231 cancer cells when treated with LEM2-loaded APTES-TCPSi-PEG-FA, by reducing cell viability lower than 50% in comparison with bulk LEM2. Despite the reduced LEM2 loading degree, which still limits its application in further in vivo assays, the results obtained herein recognize PSi-based nanodelivery systems as a promising strategy to improve LEM2 anticancer activity and bioavailability, which will be relevant for the potential use of this potent TAp73 activator in anticancer therapy.Peer reviewe

Unusual Emissions at Various Energies Prior to the Impulsive Phase of the Large Solar Flare and Coronal Mass Ejection of 4 November 2003

The GOES X28 flare of 4 November 2003 was the largest ever recorded in its class. It produced the first evidence for two spectrally separated emission components, one at microwaves and the other in the THz range of frequencies.We analyzed the pre-flare phase of this large flare, twenty minutes before the onset of the major impulsive burst. This periodis characterized by unusual activity in X-rays, sub-THz frequencies, H, and microwaves.The CME onset occurred before the onset of the large burst by about 6 min

Antifouling Marine Coatings with a Potentially Safer and Sustainable Synthetic Polyphenolic Derivative

The development of harmless substances to replace biocide-based coatings used to prevent or manage marine biofouling and its unwanted consequences is urgent. The formation of biofilms on submerged marine surfaces is one of the first steps in the marine biofouling process, which facilitates the further settlement of macrofoulers. Anti-biofilm properties of a synthetic polyphenolic compound, with previously described anti-settlement activity against macrofoulers, were explored in this work. In solution this new compound was able to prevent biofilm formation and reduce a pre-formed biofilm produced by the marine bacterium, Pseudoalteromonas tunicata. Then, this compound was applied to a marine coating and the formation of P. tunicata biofilms was assessed under hydrodynamic conditions to mimic the marine environment. For this purpose, polyurethane (PU)-based coating formulations containing 1 and 2 wt.% of the compound were prepared based on a prior developed methodology. The most effective formulation in reducing the biofilm cell number, biovolume, and thickness was the PU-based coating containing an aziridine-based crosslinker and 2 wt.% of the compound. To assess the marine ecotoxicity impact of this compound, its potential to disrupt endocrine processes was evaluated through the modulation of two nuclear receptors (NRs), peroxisome proliferator-activated receptor gamma (PPAR gamma), and pregnane X receptor (PXR). Transcriptional activation of the selected NRs upon exposure to the polyphenolic compound (10 mu M) was not observed, thus highlighting the eco-friendliness towards the addressed NRs of this new dual-acting anti-macro- and anti-microfouling agent towards the addressed NRs