Response of the Ionosphere-Plasmasphere System to Periodic Forcing

The role of different mechanisms for generating periodic variability in the ionosphere and plasmasphere is studied in this dissertation. The impact of vertically propagating waves of lower atmospheric origin on introducing periodic spatial and temporal variability in the ionosphere and plasmasphere is first investigated. This is comprised of several different aspects. Initial focus is on the seasonal, local time, and altitude dependence of longitude variations due to nonmigrating tides in the F-region and topside ionosphere/plasmasphere using a combination of observations and numerical models. This is facilitated by the development of a new method for mitigating the effect of multipath on low-Earth orbit (LEO) satellite Global Positioning System (GPS) observations. The impact of large-scale changes in tropospheric convection due to the El-Nino Southern Oscillation on the ionosphere is also explored observationally. The influence of nonmigrating tides on the global ionosphere is revealed through study of the longitude variations in the solar quiet current system. Periodic temporal variability in the ionosphere due to planetary waves originating in the lower atmosphere is also investigated. The response of the global ionosphere to the quasi-16 day planetary wave is first presented. This is followed by observational evidence demonstrating that the nonlinear interaction between planetary waves and tides is the primary mechanism responsible for low-latitude ionospheric variability during sudden stratospheric warmings. Periodic temporal variability in the ionosphere and plasmasphere of solar origin is also studied. During the declining phase of solar cycle 23, near-Earth geospace was routinely disturbed due to high-speed solar wind streams emanating from solar coronal holes. The nature of the coronal holes was such that the Earth\u27s upper atmosphere exhibited periodic behavior due to recurrent geomagnetic activity. A study of the latitude and local time response of the ionosphere to recurrent geomagnetic activity is performed herein. A method for estimating the location of the plasmapause from LEO GPS observations is also developed and applied to study periodic oscillations in the plasmapause

Mesospheric anomalous diffusion during noctilucent clouds

The Andenes specular meteor radar shows meteor-trail diffusion rates increasing on average by ~ 20% at times and locations where a lidar observes noctilucent clouds (NLCs). This high-latitude effect has been attributed to the presence of charged NLC but this study shows that such behaviors result predominantly from thermal tides. To make this claim, the current study evaluates data from three stations, at high-, mid-, and low-latitudes, for the years 2012 to 2016, comparing diffusion to show that thermal tides correlate strongly with the presence of NLCs. This data also shows that the connection between meteor-trail diffusion and thermal tide occurs at all altitudes in the mesosphere, while the NLC influence exists only at high-latitudes and at around peak of NLC layer. This paper discusses a number of possible explanations for changes in the regions with NLCs and leans towards the hypothesis that relative abundance of background electron density plays the leading role. A more accurate model of the meteor trail diffusion around NLC particles would help researchers determine mesospheric temperature and neutral density profiles from meteor radars.Public versio

Um estudo sobre a aplicação de gestão de projetos nas auditorias da CGU

Trabalho de conclusão de curso (especialização)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Departamento de Administração, Núcleo de Estudos e Pesquisas em Inovação e Estratégia, Tribunal de Contas do Distrito Federal, 2017.O presente trabalho objetiva analisar as possíveis correlações entre a condução de auditorias e a gestão de projetos

Um modelo de negociação entre Bandwidth Brokers para oferta de QoS fim-a-fim

Orientador: Edmundo Roberto Mauro MadeiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação CientificaMestrad

Stereoselective Synthesis of Selenium-Containing Glycoconjugates via the Mitsunobu Reaction

A simple and efficient route for the synthesis of new glycoconjugates has been developed.The approach acts as a model for a mini-library of compounds with a deoxy-selenosugar core joinedto a polyphenolic moiety with well-known antioxidant properties. An unexpected stereocontroldetected in the Mitsunobu key reaction led to the most attractive product showing a natural Dconfiguration. Thus, we were able to obtain the target molecules from the commercially availableD-ribose via a shorter and convenient sequence of reaction

Microwave Assisted Synthesis of Pyridophenoxazinones, a Class of Powerful Antiproliferative Compounds

In order to obtain new antiproliferative compounds good for acting through the forementioned mechanisms, including DNA intercalation and topoisomerase inhibition, our attention was focused on the derivatives of pyridophenoxazinone (PPH, 1 R=H) system, an iminoquinone containing a planar tetracyclic system suitable for intercalating DNA G-C base pairs in a site specific mode(2). Namely, we designed, after molecular modeling calculations, PPH carboxyamide derivatives holding at C-9 and C-10 positions an amino acidic chain or a sugar. Unfortunately, the real obstacle to the availability of such molecule was represented by their synthesis. Therefore, in our opinion it seems to be worthwhile to report a new microwave (μW) assisted synthetic procedure to prepare PPH carboxyamides. In order to assess the validity of our method, we applied the procedure to the synthesis of variously substituted PPHs 1 and received evidence that microwave irradiation enables the preparation of those compounds in high yields and short reaction times

Fullerene-derivates containing selenium

Over the years, fullerenes have been covalently linked to other polar structures, increasing its aqueous solubility, thereby improving its potential use for biological and biomedical applications.1 The functionalization of C60, the most study fullerene, with biomolecules shows one of the best approaches to increase their bioavailability and access the benefits of these molecules.2 C60 derivatives have shown antioxidants and antivirals propierties. In adition, remarkable examples relate with the synthesis of C60 hybrids, where the [60]fullerene is covalently connected to biological active compounds such as sugars and steroids have affinity to some nucleic acids, proteins and cellular receptors.3 In the frame of a consolidated research focused on the versatility of steroid-C60 hybrids,4 we propose the synthesis of new methanofullerenes 1 (Scheme 1) containing selenium with potential antiviral and antioxidant propierties by a synergistic activity of selenium and the C60. The new methano[60]fullerenes were prepared using a cyclopropanation reaction employed the Bingel–Hirsch protocol in a multistep synthetic procedure. The precursors malonates contained three sterols – diosgenine, cholesterol, and stradiol – and a D-selenodeoxysugar 3. These conjugates were synthetized in good yields based on the consolidated synthetic technique performed previously by our reserch group5 and a computational study was carried out. Theoretical calculations using the DFT-PBE method and 6-311G(d,p) basis set, were performed to predict the most stable conformations for the synthesized conjugates (2). For the more, the applications of the novel steroid-selenosugar conjugates were also evaluated in medicinal chemistry, in particular, was explored their potential application as anti-SarsCov-2 agents. The molecular docking suggested that the conjugates form H-bonds with the active residues involved in the interaction of RBD-SarsCov-2 with ACE-2. How RBD protein plays an important role in the entry of virus in the cellule, the conjugates could be considerate with potential antivirals propierties

Infrastructure needs on latitudinal and longitudinal chains of co-located ground-based observations

The generation, propagation, and dissipation of atmospheric planetary waves (PW), tides, and gravity waves (GW) constitute the primary mechanism that transfers energy and momentum from the atmosphere to space. While single-location ground-based observations have been making successful measurements of such waves over the past decades, NSF funded ground-based observations are not yet systematically distributed at the same latitude or the same longitude, despite the importance of latitudinal and longitudinal dependence of dynamical processes like large scale wave propagation, interaction, and dissipation. This white paper discusses the significance and potential of coordinating a chain of ground-based instruments with the current large facilities to extend the latitudinal and longitudinal observational coverage in the American sector (both South and North America). We further discuss the benefits of co-locating heterogeneous instruments with different techniques and different temporal/spatial resolution/coverage, for instance, radio instruments (e.g., ISR, HF radar, meteor radar), optical instruments (e.g., FPI, lidar, airglow imager), magnetometers, ionosondes, sounding rockets and so on

Geomagnetic lunar and solar daily variations during the last 100 years

This paper describes long-term changes in the geomagnetic lunar (L) and solar (S) daily variations. We analyze the eastward component of the geomagnetic field observed at eight midlatitude stations during 1903–2012. The amplitude and phase for the semidiurnal component of the L and S variations are examined. Both L and S amplitudes correlate with the solar activity index F10.7, revealing a prominent 11 year solar cycle. In both cases, the correlation is slightly better with inline image than F10.7. The sensitivity of the L variation to solar activity is comparable with that of the S variation. The solar cycle effect is also found in the phase of the S variation but not apparent in the phase of the L variation. The ratio in the amplitude of the L to S variation shows a long-term decrease (approximately 10% per century), which may be due to a reduction in lunar tidal waves from the lower atmosphere to the upper atmosphere in association with climate change

New Seleno-Glyconjugates for Nutraceutical Application

Oxidative stress is a disequilibrium redox condition that occurs due to high concentration of prooxidant reactive species (RS) and, by comparison, a lower concentration of endogenous antioxidants in the body.1 Oxidative stress, caused by RS, is involved into the genesis of different pathologies such as inflammatory bowel disease, cardiovascular disease, Alzheimer’s disease, diabetes and cancer.2 Nutraceuticals could be used to prevent oxidative stress as an additional health benefit along with nutrition.1 The use of exogenous antioxidants can ameliorate this stressful condition and restore the redox disequilibrium.3 Polyphenols have a potential health-promoting effect, however, show a low bioavailability.4 For this reason, synthesis of organic seleniumcompounds combined to (poly)phenolic compounds could increase the solubility and exert their potential synergistic antioxidant effects. The approach proposed consists of preparing the D-ribose derivative 1 to obtain the donor 2 then employed to produce glycoconjugates containing well known (poly)phenols through a Mitsunobu reaction.5 To assess the bioactivity of selenoglycoconjugates, DPPH and ABTS antiradical assays were performed, while the effects on cell proliferation were preliminarily investigated on SH-SY5Y cells. The phenol moiety greatly affected both the antiradical efficacy and the mitochondrial redox activity. The glycoconjugates, especially at the highest tested concentrations, exhibited cytotoxic effects lower than that of unconjugated phenolic compounds, underlining the mitigating impact of selenosugar