108 research outputs found
Satellite traces, range spread-F occurrence, and gravity wave propagation at the southern anomaly crest
Range spread-F (RSF) and occurrence of “satellite” traces prior to RSF onset were studied at the southern peak of the ionospheric equatorial anomaly (EA). Ionograms recorded in September 2007 at the new ionospheric station of Tucumán, Argentina (26.9° S, 294.6° E, dip latitude 15.5° S), by the Advanced Ionospheric Sounder (AIS) developed at the Istituto Nazionale di Geofisica e Vulcanologia INGV), were considered.
Satellite traces (STs) are confirmed to be a necessary precursor to the appearance of an RSF trace on the ionograms.
Moreover, an analysis of isoheight contours of electron density seems to suggest a relationship between RSF occurrence
and gravity wave (GW) propagation
Unusual nighttime impulsive foF2 enhancement below the southern anomaly crest under geomagnetically quiet conditions
An unusual nighttime impulsive electron density enhancement was observed on 6
March 2010 over a wide region of South America, below the southern crest of the equatorial anomaly, under low solar activity and quiet geomagnetic conditions. The phenomenon was observed almost simultaneously by the F2 layer critical frequency ( foF2) recorded at
three ionospheric stations which are widely distributed in space, namely Cachoeira Paulista (22.4°S, 44.6°W, magnetic latitude 13.4°S), São José dos Campos (23.2°S, 45.9°W,
magnetic latitude 14.1°S), Brazil, and Tucumán (26.9°S, 65.4°W, magnetic latitude
16.8°S), Argentina. Although in a more restricted region over Tucumán, the phenomenon was also observed by the total electron content (TEC) maps computed by usingmeasurements from 12 GPS receivers. The investigated phenomenon is very particular because besides being of brief duration, it is characterized by a pronounced compression of the ionosphere. This compression was clearly visible both by the virtual height of the base of the F region (h′F) recorded at the aforementioned ionospheric stations, and by both the vertical electron density profiles and the slab thickness computed over Tucumán. Consequently, neither an
enhanced fountain effect nor plasma diffusion from the plasmasphere can be considered as the single cause of this unusual event. A thorough analysis of isoheight and isofrequency ionosonde plots suggest that traveling ionospheric disturbances (TIDs) caused by gravity
wave (GW) propagation could have likely played a significant role in causing the
phenomenon
Carbohydrate reserves and seed development : an overview
Seeds are one of the most important food sources, providing humans and animals with essential nutrients. These nutrients include carbohydrates, lipids, proteins, vitamins and minerals. Carbohydrates are one of the main energy sources for both plant and animal cells and play a fundamental role in seed development, human nutrition and the food industry. Many studies have focused on the molecular pathways that control carbohydrate flow during seed development in monocot and dicot species. For this reason, an overview of seed biodiversity focused on the multiple metabolic and physiological mechanisms that govern seed carbohydrate storage function in the plant kingdom is required. A large number of mutants affecting carbohydrate metabolism, which display defective seed development, are currently available for many plant species. The physiological, biochemical and biomolecular study of such mutants has led researchers to understand better how metabolism of carbohydrates works in plants and the critical role that these carbohydrates, and especially starch, play during seed development. In this review, we summarize and analyze the newest findings related to carbohydrate metabolism\u2019s effects on seed development, pointing out key regulatory genes and enzymes that influence seed sugar import and metabolism. Our review also aims to provide guidelines for future research in the field and in this way to assist seed quality optimization by targeted genetic engineering and classical breeding programs
The new ionospheric station of Tucumán: first results
An Advanced Ionospheric Sounder, built at the Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy, was
installed at Tucumán, Argentina, particularly interesting for its location, near the southern peak of the ionospheric
equatorial anomaly. The aim of this installation is to collect a large number of continuous data useful both to
study the dynamics of the equatorial ionospheric plasma and to develop reliable regional ionospheric prediction
models. Moreover this ionosonde will contribute to the ionospheric database and real time knowledge of Southern
Hemisphere ionospheric conditions for space weather applications. The ionosonde is completely programmable
and two PCs support the data acquisition, control, storage and on-line processing. In this work the first
results, in terms of ionograms and autoscaled characteristics, are presented and briefly discussed
Some considerations for different time-domain signal processing of pulse compression radar
Radar technology has for a long time used various systems that allow detection under high-resolution conditions, while emitting at the same time low peak power. Among these systems, transmitted pulse encoding by means of biphasic codes has been used for the advanced ionospheric sounder that was developed by the AIS-INGV ionosonde. In the receiving process, suitable decoding of the signal must be accomplished. This can be achieved in both the time and the frequency domains. Focusing on the time domain, different approaches are possible. In this study, two of these approaches have been compared, using data acquired by the AIS-INGV and processed by means of software tools (mainly Mathcad©). The analysis reveals the differences under both noiseless and noisy conditions, although this does not allow the conclusive establishment as to which method is better, as each of them has benefits and drawbacks
Exosomes released upon mitochondrial ASncmtRNA knockdown reduce tumorigenic properties of malignant breast cancer cells
Indexación ScopusDuring intercellular communication, cells release extracellular vesicles such as exosomes, which contain proteins, ncRNAs and mRNAs that can influence proliferation and/or trigger apoptosis in recipient cells, and have been proposed to play an essential role in promoting invasion of tumor cells and in the preparation of metastatic niches. Our group proposed the antisense non-coding mitochondrial RNA (ASncmtRNA) as a new target for cancer therapy. ASncmtRNA knockdown using an antisense oligonucleotide (ASO-1537S) causes massive death of tumor cells but not normal cells and strongly reduces metastasis in mice. In this work, we report that exosomes derived from ASO-1537S-treated MDA-MB-231 breast cancer cells (Exo-1537S) inhibits tumorigenesis of recipient cells, in contrast to exosomes derived from control-ASO-treated cells (Exo-C) which, in contrast, enhance these properties. Furthermore, an in vivo murine peritoneal carcinomatosis model showed that Exo-1537S injection reduced tumorigenicity compared to controls. Proteomic analysis revealed the presence of Lactadherin and VE-Cadherin in exosomes derived from untreated cells (Exo-WT) and Exo-C but not in Exo-1537S, and the latter displayed enrichment of proteasomal subunits. These results suggest a role for these proteins in modulation of tumorigenic properties of exosome-recipient cells. Our results shed light on the mechanisms through which ASncmtRNA knockdown affects the preparation of breast cancer metastatic niches in a peritoneal carcinomatosis model. © 2020, The Author(s).https://www-nature-com.recursosbiblioteca.unab.cl/articles/s41598-019-57018-
Observatorio ionosferico BahĂa Blanca : Primeros resultados
La ionĂłsfera presenta diferentes comportamientos en baja, media y alta latitud. En Septiembre de 2016, en colaboraciĂłn con el MINCYT y el Instituto de GeofĂsica y VulcanologĂa de Roma (INGV) y con el apoyo de la Universidad Nacional de Tucumán (UNT), la Universidad TecnolĂłgica Nacional (UTN) instalĂł un moderno ionosonda (Advanced Ionospheric Sounder - AIS) en la Facultad Regional BahĂa Blanca (FRBB) (38,7Âş S, 297,7Âş E).
En este trabajo se presentan los primeros resultados obtenidos con el ionosonda de la FRBB, los que corresponden a Octubre de 2016. Usando medianas y cuartiles de la frecuencia crĂtica de la regiĂłn F2 (foF2) se analiza el comportamiento de la ionĂłsfera sobre esta estaciĂłn de latitud media y, además, se lo compara con el observado en baja latitud, para lo cual se utilizan mediciones simultáneas realizadas con el AIS de Tucumán (26,9Âş S; 294,6Âş E). Las mediciones obtenidas con el AIS de la FRBB, tambiĂ©n son utilizadas para analizar la confiabilidad del mapa horario de foF2 publicado por el Ionospheric Prediction Service (IPS) de Australia.
Los resultados muestran que sobre BahĂa Blanca foF2 presenta una variaciĂłn diaria con un mĂnimo entre la 1 UT y las 9 UT (antes de las 5 LT) y un máximo a las 17 UT (aprox. 13 LT), para el mes considerado. El estudio comparativo con baja latitud, muestra que los valores de la frecuencia crĂtica de la regiĂłn F2 de la ionĂłsfera sobre Tucumán son mayores que los de BahĂa Blanca, lo que se debe a la influencia de la AnomalĂa Ecuatorial sobre la ionĂłsfera de baja latitud. Por otro lado, la variabilidad de foF2 sobre BahĂa Blanca mostrĂł ser menor que la correspondiente a la de Tucumán.
Además, se muestra un ejemplo de un mapa de foF2 publicado por el IPS con buenos valores para Tucumán pero con una marcada sobreestimaciĂłn de esta magnitud ionosfĂ©rica para BahĂa Blanca. Esta disparidad de resultados se debe a que el IPS utiliza los datos del AIS de Tucumán para construir el mencionado mapa pero no usa las mediciones del nuevo ionosonda de la FRBB. Se destaca que los datos de la FRBB fueron ofrecidos al IPS para mejorar la confiabilidad del mapa mencionado en la zona Central - Sur de nuestro paĂs.Eje: Acoplamiento Solar-Terrestre en el geoespacio.Facultad de Ciencias AstronĂłmicas y GeofĂsica
The Antidiabetic Effect of MSCs Is Not Impaired by Insulin Prophylaxis and Is Not Improved by a Second Dose of Cells
Type 1 diabetes mellitus (T1D) is due to autoimmune destruction of pancreatic beta-cells. Previously, we have shown that intravenously administered bone marrow-derived multipotent mesenchymal stromal cells (MSCs) allows pancreatic islet recovery, improves insulin secretion and reverts hyperglycemia in low doses streptozotocin (STZ)-induced diabetic mice. Here we evaluate whether insulin prophylaxis and the administration of a second dose of cells affect the antidiabetic therapeutic effect of MSC transplantation. Insulitis and subsequent elimination of pancreatic beta-cells was promoted in C57BL/6 mice by the injection of 40 mg/kg/day STZ for five days. Twenty-four days later, diabetic mice were distributed into experimental groups according to if they received or not insulin and/or one or two doses of healthy donor-derived MSCs. Three and half months later: glycemia, pancreatic islets number, insulinemia, glycated hemoglobin level and glucose tolerance were determined in animals that did not received exogenous insulin for the last 1.5 months. Also, we characterized MSCs isolated from mice healthy or diabetic. The therapeutic effect of MSC transplantation was observed in diabetic mice that received or not insulin prophylaxis. Improvements were similar irrespective if they received one or two doses of cells. Compared to MSCs from healthy mice, MSCs from diabetic mice had the same proliferation and adipogenic potentials, but were less abundant, with altered immunophenotype and no osteogenic potential
Low-latitude equinoctial spread-F occurrence at different longitude sectors under low solar activity
We present the results of a comparative study of spread-F signatures over five low-latitude sites: Chiangmai (CGM; 18.8° N, 98.9° E, mag. Lat. 8.8° N), Thailand; Tanjungsari (TNJ; 6.9° S, 107.6° E, mag. Lat. 16.9° S), Indonesia; Palmas (PAL; 10.2° S, 311.8° E, mag. Lat. 0.9° S) and SĂŁo JosĂ© Dos Campos (SJC; 23.2° S, 314.1° E, mag. Lat. 14.0° S), Brazil; and Tucumán (TUC; 26.9° S, 294.6° E, mag. Lat. 16.8° S), Argentina. The investigation was based on simultaneous ionograms recorded by an FMCW (frequency-modulated continuous-wave) at CGM, an IPS-71 (digital ionosonde from KEL aerospace) at TNJ, a CADI (Canadian Advanced Digital Ionosonde) at PAL and SJC, and an AIS-INGV (Advanced Ionospheric Sounder – Istituto Nazionale di Geofisica e Vulcanologia) at TUC, during the equinoctial periods March–April (R12 = 2.0 and R12 = 2.2) and September–October (R12 = 6.1 and R12 = 7.0) 2009, for very low solar activity. Spread-F signatures were categorized into two types: the range spread-F (RSF) and the frequency spread-F (FSF). The study confirms that the dynamics and the physical processes responsible for these phenomena are actually complicated. In fact, the features that arise from the investigation are different, depending on both the longitude sector and on the hemisphere. For instance, TUC, under the southern crest of the ionospheric equatorial ionization anomaly (EIA), shows a predominance of RSF signatures, while both SJC, under the southern crest of EIA but in a different longitude sector, and CGM, under the northern crest of EIA, show a predominance of FSF signatures. Moreover, the spread-F occurrence over the longitude sector that includes CGM and TNJ is significantly lower than the spread-F occurrence over the longitude sector of PAL, SJC, and TUC.Fil: Pezzopane, M.. Istituto Nazionale Di Geofisica E Vulcanologia; Italia;Fil: Zuccheretti, E.. Istituto Nazionale Di Geofisica E Vulcanologia; Italia;Fil: Abadi, P.. Indonesian National Institute of Aeronautics and Space. Space Science Center. Division of Ionosphere and Telecommunication; Indonesia;Fil: de Abreu, A. J.. Universidade do Vale do ParaĂba; Brazil;Fil: de Jesus, R.. Universidade do Vale do ParaĂba; Brazil;Fil: Fagundes, P. R.. Universidade do Vale do ParaĂba; Brazil;Fil: Supnithi, P.. King Mongkut’s Institute of Technology Ladkrabang . Faculty of Engineering; Tailandia;Fil: Rungraengwajiake, S.. King Mongkut’s Institute of Technology Ladkrabang . Faculty of Engineering; Tailandia;Fil: Nagatsuma, T.. National Institute of Information and Communications Technology. Space Weather and Environment Informatics Laboratory; JapĂłn;Fil: Tsugawa, T.. National Institute of Information and Communications Technology. Space Weather and Environment Informatics Laboratory; JapĂłn;Fil: Cabrera, Miguel Angel. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de FĂsica. Laboratorio de Ionosfera; Argentina; Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Electricidad, ElectrĂłnica y ComputaciĂłn. Laboratorio de Telecomunicaciones; Argentina; Universidad TecnolĂłgica Nacional. Facultad Regional Tucumán. Centro de InvestigaciĂłn de AtmĂłsfera Superior y RadiopropagaciĂłn; Argentina;Fil: Ezquer, Rodolfo Gerardo. Universidad TecnolĂłgica Nacional. Facultad Regional Tucumán. Centro de InvestigaciĂłn de AtmĂłsfera Superior y RadiopropagaciĂłn; Argentina; Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina; Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de FĂsica. Laboratorio de Ionosfera; Argentina
The new ionospheric station of San Miguel de Tucumán
At the end of August 2007 an Advanced Ionospheric Sounder (AIS), built at the Istituto Nazionale
di Geofisica e Vulcanologia (INGV), Rome, Italy, was installed at San Miguel de Tucumán,
Argentina (geographical coordinates: 26.9 S, 294.6 E; magnetic coordinates: 15.5 S, 3.8 E),
particularly interesting for its location, near the southern peak of the equatorial anomaly.
AIS-INGV is a digital low-power pulse-compressed ionosonde. In order to reduce the transmitted
power, weight, size, power consumption, and to have an excellent reliability, advanced HF-radar
techniques were employed. The ionosonde is also equipped with Autoscala, a software able to
perform an automatic scaling of the ionogram
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