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The diurnal cycle of precipitation in the Amazon Basin (AB) is not homogeneous, varying in its intensity, time of occurrence of precipitation peaks and in the shape of its diurnal distribution. This study presents a seasonal characterization of the mean diurnal cycle of precipitation in the AB from IMERG Final Run (Δx = 0.1° and Δt = 30 min) database from 2001 to 2020. Diurnal and semi-diurnal oscillations were studied by harmonics analysis, i.e., using the first and second harmonics, respectively. Harmonic metrics of normalized amplitude (AN), phase and mean hourly precipitation rate were analyzed. The AN showed pixels within the AB with bimodal/uniform or unimodal distribution associated with the occurrence of two peaks (or none) or a single peak during the day. The phase of the first harmonic shows the time of occurrence of the precipitation rates peaks, as well as the displacement of the precipitation systems. The regionalization of the diurnal cycle was performed using the K-Means technique, showing that AB presents six clusters along its domain based mainly on the phase of the first harmonic. The spatial configuration of clusters showed seasonal variation, being modulated by the South American Monsoon System and the large-scale mechanisms responsible for triggering convection. However, their intensity, the shape of the diurnal distribution and the timing of precipitation peaks are modulated by local factors. [ABSTRACT FROM AUTHOR]

Daily data on COVID-19 infections and deaths tend to possess weekly oscillations. The purpose of this work is to forecast COVID-19 data with partially cyclical fluctuations. A partially periodic oscillating ARIMA model is suggested to enhance the predictive performance. The model, optimized for improved prediction, characterizes and forecasts COVID-19 time series data marked by weekly oscillations. Parameter estimation and out-of-sample forecasting are carried out with data on daily COVID-19 infections and deaths between January 2021 and October 2022 in the USA, Germany, and Brazil, in which the COVID-19 data exhibit the strongest weekly cycle behaviors. Prediction accuracy measures, such as RMSE, MAE, and HMAE, are evaluated, and 95% prediction intervals are constructed. It was found that predictions of daily COVID-19 data can be improved considerably: a maximum of 55–65% in RMSE, 58–70% in MAE, and 46–60% in HMAE, compared to the existing models. This study provides a useful predictive model for the COVID-19 pandemic, and can help institutions manage their healthcare systems with more accurate statistical information. [ABSTRACT FROM AUTHOR]

Continental dunes are key features for the study of climatic oscillations that occurred during the Quaternary. These deposits occur in different spatial contexts in Brazil and reflect their formative paleoenvironmental and paleoclimatic conditions. The present work proposes a synthesis of the literature on the subject over the last 30 years, integrating geochronological and environmental information on the continental dunes present in the Brazilian territory. The data from dating by LOE and TL indicate the occurrence of wind deposition from the Middle Pleistocene (253.8±19.0ka) to the present (0.165±0.025ka) with alternation between periods of lower and higher activity. Parabolic dunes, sand sheets, and deflation basins (blowouts) predominate in the studied areas. Cyclical and anomalous mechanisms, such as Palei-ENSO, appear to have been responsible for the onset of drier phases, leadind to a greater supply of sediments and the consequent formation of dune deposits. The good resolution of the chronological data also suggests that the dunes act as important geo-archives for studying environmental changes with medium to short recurrence intervals. [ABSTRACT FROM AUTHOR]

The essay examines the critical discourse on music that was established in Brazil and the relationship of the intellectuality with this art, demonstrating that parameters of national-modernism were always at the base of both. In a historical sequence, it starts with the Week of Modern Art (1922) and follows its evolutions, highlighting and interpreting, among the various episodes and conceptual revisionisms over the years, the oscillations of critical interest in relation to classical and popular musical manifestations. The hypothesis is that, in the contemporary scenario, the propulsive force of the national-modernist argument has ended, since it is no longer capable of articulating the questions posed by today's musical productions. [ABSTRACT FROM AUTHOR]

In different parts of the world, aphid populations and their natural enemies are influenced by landscapes and climate. In the Neotropical region, few long-term studies have been conducted, maintaining a gap for comprehension of the effect of meteorological variables on aphid population patterns and their parasitoids in field conditions. This study describes the general patterns of oscillation in cereal winged aphids and their parasitoids, selecting meteorological variables and evaluating their effects on these insects. Aphids exhibit two annual peaks, one in summer–fall transition and the other in winter-spring transition. For parasitoids, the highest annual peak takes place during winter and a second peak occurs in winter–spring transition. Temperature was the principal meteorological regulator of population fluctuation in winged aphids and parasitoids during the year. The favorable temperature range is not the same for aphids and parasitoids. For aphids, temperature increase resulted in population growth, with maximum positive effect at 25°C. Temperature also positively influenced parasitoid populations, but the growth was asymptotic around 20°C. Although rainfall showed no regulatory function on aphid seasonality, it influenced the final number of insects over the year. The response of aphids and parasitoids to temperature has implications for trophic compatibility and regulation of their populations. Such functions should be taken into account in predictive models. [ABSTRACT FROM AUTHOR]

The Madden Julian Oscillation (MJO) is the main source of intraseasonal variability in the tropics. MJO modulates rainfall in remote areas in the Southern Hemisphere by exciting tropical and extratropical wave trains. We use newly released reanalysis data to analyze how the Quasi‐Biennial Oscillation (QBO) can influence the MJO's effects over the Southern Hemisphere, focusing on precipitation anomalies over South America. The anomalies in the intensity of the South Atlantic Convergence Zone (SACZ) and precipitation over Southeastern South America during MJO phases 1 and 4 are intensified during the easterly QBO. The extratropical wave train excited by the anomalous convection over the maritime continent during MJO phase 4 is affected by the QBO, with a stronger, better‐defined pattern during westerly QBO. The conclusions are supported by a perturbation experiment of a case study, conducted using a high‐top atmospheric global climate model where the QBO and MJO are controlled. Plain Language Summary: Subseasonal to seasonal prediction remains challenging in the current forecast models. Previous studies have shown that the Quasi‐Biennial Oscillation (QBO) can influence the intensity and development of the Madden Julian Oscillation (MJO). Here, the consequences of this modulation on the remote effects of the MJO in the Southern Hemisphere are analyzed using reanalysis and perturbation experiments in an atmospheric global climate model. The rainfall anomalies related to the MJO in South America are more intense and widespread during easterly QBO over the South Atlantic Convergence Zone and southern Brazil than during westerly QBO. Thus, the inclusion of the state of the QBO in the estimate of the expected rainfall associated with the MJO is crucial to improve forecasts in the region. Key Points: The Quasi‐Biennial Oscillation (QBO) modulates the impacts of the Madden Julian Oscillation (MJO) in the Southern HemisphereMJO‐related rainfall anomalies in the South Atlantic Convergence Zone are intensified during easterly QBOEThe extratropical wave train forced by the anomalous convection in MJO phase 4 is intensified under QBOW [ABSTRACT FROM AUTHOR]

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Several strong sea-level oscillations in the southern region of Brazil with periods in the range of tsunamis, but attributed to atmospheric disturbances, have been publicized in the media or in scientific articles in recent years. However, only a few were registered by instruments. On October 29, 2019, a squall line, linked to an atmospheric storm and a positive jump in atmospheric pressure, spread from south to north along the coast of Santa Catarina. The atmospheric disturbance generated, through Proudman's resonance mechanism, at least two tsunami-like waves with heights greater than 0.70 m and periods around 15 min. These waves were recorded by a network of tide gauges, allowing to monitor their evolution and transformations for more than 200 km. Although there were no reported fatalities, there were significant material losses linked to this occurrence. The objective of the present work is to analyze and connect atmospheric conditions and wave signals in order to further understand the circumstances leading to the formation of this type of event in the southern coast of Brazil. [ABSTRACT FROM AUTHOR]

Study Question: How are progesterone (P4)-induced repetitive intracellular Ca2+ concentration ([Ca2+]i) signals (oscillations) in human sperm generated?Summary Answer: P4-induced [Ca2+]i oscillations are generated in the flagellum by membrane potential (Vm)-sensitive Ca2+-influx through CatSper channels.What Is Known Already: A subset of human sperm display [Ca2+]i oscillations that regulate flagellar beating and acrosome reaction. Although pharmacological manipulations indicate involvement of stored Ca2+ in these oscillations, influx of extracellular Ca2+ is also required.Study Design, Size, Duration: This was a laboratory study that used >20 sperm donors and involved more than 100 separate experiments and analysis of more than 1000 individual cells over a period of 2 years.Participants/materials, Setting, Methods: Semen donors and patients were recruited in accordance with local ethics approval from Birmingham University and Tayside ethics committees. [Ca2+]i responses and Vm of individual cells were examined by fluorescence imaging and whole-cell current clamp.Main Results and the Role Of Chance: P4-induced [Ca2+]i oscillations originated in the flagellum, spreading to the neck and head (latency of 1-2 s). K+-ionophore valinomycin (1 µM) was used to investigate the role of membrane potential (Vm). Direct assessment by whole-cell current-clamp confirmed that Vm in valinomycin-exposed cells was determined primarily by K+ equilibrium potential (EK) and was rapidly 'reset' upon manipulation of [K+]o. Pre-treatment of sperm with valinomycin ([K+]o = 5.4 mM) had no effect on the P4-induced [Ca2+] transient (P = 0.95; eight experiments), but application of valinomycin to P4-pretreated sperm suppressed activity in 82% of oscillating cells (n = 257; P = 5 × 10-55 compared to control) and significantly reduced both the amplitude and frequency of persisting oscillations (P = 0.0001). Upon valinomycin washout, oscillations re-started in most cells. When valinomycin was applied in saline with elevated [K+], the inhibitory effect of valinomycin was reduced and was dependent on EK (P = 10-25). Amplitude and frequency of [Ca2+]i oscillations that persisted in the presence of valinomycin showed similar sensitivity to EK (P < 0.01). The CatSper inhibitor RU1968 (4.8 and 11 µM) caused immediate and reversible arrest of activity in 36% and 96% of oscillating cells, respectively (P < 10-10). Quinidine (300 µM) which blocks the sperm K+ current (IKsper) completely, inhibited [Ca2+]i oscillations.Large Scale Data: N/A.Limitations, Reasons For Caution: This was an in-vitro study and caution must be taken when extrapolating these results to in-vivo regulation of sperm.Wider Implications Of the Findings: [Ca2+]i oscillations in human sperm are functionally important and their absence is associated with failed fertilisation at IVF. The data reported here provide new understanding of the mechanisms that underlie the regulation and generation (or failure) of these oscillations.Study Funding/competing Interest(s): E.T.-N. was in receipt of a postgraduate scholarship from the CAPES Foundation (Ministry of Education, Brazil). E.M-M received travel funds from the Programa de Apoyo a los Estudios de Posgrado (Maestria y Doctorado en Ciencias Bioquimicas-Universidad Autonoma de Mexico). SGB and CLRB are recipients of a Chief Scientist Office (NHS Scotland) grant TCS/17/28. The authors have no conflicts of interest. [ABSTRACT FROM AUTHOR]

The El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are large-scale climatic phenomena affecting atmospheric and oceanic teleconnections, and thus triggering weather events at different temporal and spatial scales, both in tropical and extratropical areas. During 11 years (2007–2017), the influence of ENSO events (El Niño, La Niña and neutral), ENSO types (canonical and Modoki) and PDO phases (cold and warm) on meteorological conditions and macrobenthic invertebrates were analyzed in two distinct (tide-dominated and river-dominated) subtropical estuaries of Southern Brazil. The estuarine macrobenthic communities differed markedly, with higher species richness in the tide-dominated estuary (146 taxa) than river-dominated (44). We showed that long-term variability of benthic macrofauna in both estuaries was strongly influenced by the PDO and ENSO events. However, the signs of PDO and ENSO effects differed between the estuaries. While the main modulating force of the decadal variability of the macrofauna of the tide-dominated estuary was the PDO (19%), the river-dominated estuary was primarily influenced by the ENSO (9%). Besides, PDO and ENSO teleconnections have combined effects, with higher macrofauna dissimilarities during constructive periods (PDO Positive/EL Niño vs. PDO Negative/La Niña). Our findings indicate that: (1) The effects of the ENSO on coastal areas are dependent of the spatial scale and the intrinsic characteristics of each estuary; (2) Studies relating ENSO and biodiversity should consider the ENSO type (Modoki and canonical) and interdecadal modes, such as PDO, because the location of the warm pools and the intensity of induced heating affect the atmospheric teleconnections. [ABSTRACT FROM AUTHOR]

The Eastern Pacific (EP) and Central Pacific (CP) El Niño‐Southern Oscillation (ENSO) types and their impacts on the tropical North Atlantic (TNA) SST variability and 15°N–15°S South American precipitation during the warm and cold phases of the Atlantic Multidecadal Oscillation (WAMO and CAMO) were evaluated during the 1901–2012 period. The results show more frequent ENSO events during the CAMO. The El Niño (EN) (La Niña [LN]) events, regardless of type (EP or CP), during the WAMO (CAMO) were accompanied by a warming (cooling) in the TNA after its mature phases. In these cases, extratropical teleconnection patterns are established through variations in the Pacific/North America (PNA) teleconnection pattern and are accompanied by variations in the Walker circulation. For the EN (LN) in the CAMO (WAMO), the tropical teleconnections occur predominant, through the Walker cell and the zonal inter‐basin gradient, which is intensified due to the SST gradient between the eastern equatorial Pacific (non‐neutral anomalies) and the equatorial Atlantic (neutral anomalies). These circulation pattern changes affect the precipitation patterns in the 15°N–15°S South American sector during December–January–February (D(0)JF(+1)) and March–April–May (MAM(+1)). The EP EN (EPEN) events are associated with the intensification of the negative precipitation anomalies in northeastern Brazil (NEB) during the WAMO and in the central part of the Amazon during the CAMO. In the case of CP EN (CPEN) events, the greatest differences between the AMO phases occur during MAM(+1), with reverse sign anomalies over northwestern South America. In the case of LN events, the largest differences occur in NEB, with reduced rainfall in the WAMO, regardless of type EP or CP. The results presented here highlight the role of low frequency oscillations in defining the teleconnection patterns between tropical Pacific and Atlantic Oceans, not discussed previously. [ABSTRACT FROM AUTHOR]

Using airglow data from an all-sky imager deployed at São João do Cariri (7.4 ∘ S, 36.5 ∘ W), the start times of equatorial plasma bubbles was studied in order to investigate the day-to-day variability of this phenomenon. Data from a period over 10 years were analyzed from 2000 to 2010. Semimonthly oscillations were clearly observed in the start times of plasma bubbles from OI6300 airglow images during this period of observation, and four case studies (September 2003, September–October 2005, November 2005 and January 2008) were chosen to show in detail this kind of modulation. Since the airglow measurements are not continuous in time, more than one cycle of oscillation in the start times of plasma bubbles cannot be observed from these data. Thus, data from a digisonde at São Luís (2.6 ∘ S, 44.2 ∘ W) in November 2005 were used to corroborate the results. Technical/climate issues did not allow one to observe the semimonthly oscillations simultaneously by the two instruments, but from October to November 2005 there was a predominance of this oscillation in the start times of the irregularities over Brazil. Besides, statistical analysis for the data in the whole period of observation has shown that the lunar tide, which has semimonthly variability, is likely the main forcing for the semimonthly oscillation in the start times of equatorial plasma bubbles. The presence of this oscillation can contribute to the day-to-day variability of equatorial plasma bubbles. [ABSTRACT FROM AUTHOR]

The presence of wave‐like structures in the planetary boundary layer and their influence on the scalar fluxes and on the surface energy balance were investigated analyzing one year of continuous measurements collected in southern Brazil. Submeso oscillating patterns in the wind velocity components, temperature and scalar (CO2, H2O) concentrations were isolated using their auto‐correlation functions. The analysis showed that low wind speeds are necessary to trigger wavy motions. During night‐time, in the presence of large vertical temperature gradients, horizontal meandering and internal gravity waves are dominant features of the stable boundary layer. Furthermore, a significant number of meandering cases were identified also during daytime in neutral conditions associated with low values of net radiation. One case‐study showed how, during daytime, the wave‐like patterns may be triggered by variations in the net radiation. Spectral analysis on the whole dataset showed that oscillations in the wind velocity and temperature field are frequently associated with CO2 and H2O wavy patterns with similar time‐scales. These non‐turbulent oscillations produce unpredictable large‐scale contributions to vertical fluxes of temperature and scalar concentrations. The energy budget analysis showed how the choice of a proper averaging time filters out these contributions and improves the energy budget closure, as well as the estimation of the net ecosystem exchange. The results confirm the influence of submeso motions in scalar dispersion, flux patterns and surface energy balance during low wind speed conditions and stable stratification. [ABSTRACT FROM AUTHOR]

Brazil is an extensive country with five administrative regions that have different climates, mainly due to their geographic locations. The El Niño-Southern Oscillation influences the regime of temperature and precipitation of the Brazilian regions, which can directly affect the thermal discomfort of the population. The objective of this study was to evaluate the human thermal discomfort index (HDI) in the five regions of Brazil for El Niño, La Niña, and neutral years from 1979 to 2017, as well as the influence of the degree of intensity of the Pacific Ocean anomaly in the thermal conditions of the Brazilian regions. Monthly data on air temperature and dewpoint temperature obtained from the ERA-Interim reanalysis were used. The HDI was calculated using specific equations. The results were analyzed by means of composition fields. From the results, it was possible to conclude that the El Niño and La Niña phenomena influence the HDI of the Brazilian regions. El Niño increases the discomfort due to the heat and the La Niña causes them to decrease. This study is important since these phenomena, by influencing thermal conditions, directly affect the well-being and health of the Brazilian population. [ABSTRACT FROM AUTHOR]

The Quadrilátero Ferrífero is one of the most remarKable mountainous areas in the Minas Gerais State, Southeastern Brazil. The evolution of the regional relief during the Late Cenozoic reveals a major role of the river work. Aiming to improve the understanding of regional geomorphology, various surveys on river levels and fluvial successions were undertaken in recent decades. However, there is a lack of more regionalized analyzes that contemplate more than one fluvial valley. From new surveys on fluvial depositional levels and successions and from a rereading of data in the literature about the area, this paper discusses the river levels and fluvial successions of the upper Doce river basin. This river catchment contains the drainage of the eastern and southern parts of the Quadrilátero Ferrífero. In this way, it is aimed to take a first step to the understanding of the geomorphological events responsible for the formation of the relief in the Quadrilátero Ferrífero. The results reveal a dynamic relief, sensitive to tectonic forces and climatic oscillations of the Late Quaternary. The fluvial levels were dated between 2-140 Ka using Optically Stimulated Luminescence (OSL) and permitted the rereading of previous data. Most of these levels are paired and cut-in-bedrock, revealing the rhythm of fluvial downcutting in response to the regional uplift. The OSL dating allowed the association of some fluvial levels with climatic oscillations. Fluvial successions accumulared under driest/coldest periods were turned into thick duricrusts. [ABSTRACT FROM AUTHOR]

A survey on the production of castor beans in the northeastern region of Brazil between 1990 and 2016 is provided. Production is identified by gross production value, verifying the level of variables, such as harvest area, mean productivity and price, affecting prices through growth oscillations. The shift-share model was employed and results were discussed. They are relevant indicators for the planning of castor bean production, pinpointing the great influence of production in the state of Bahia and great adaptability in other regions, with details on the behavior of production phases over the years under analysis. [ABSTRACT FROM AUTHOR]

Sea level oscillations in time scales between hours and days have a great vertical amplitude regarding the low lying coastal gradient of the beaches in the Rio Grande do Sul coast. However, the mechanism of oscillations is poorly understood since the scarcity of observational data makes it impossible to determine the forces that control sea level oscillations. Therefore, hourly sea level and wind time series with a time period of 650 days were examined. It has been found that the mean tidal and subtidal amplitudes were very similar to each other and that a considerable portion of the energy from sea level oscillations was due to astronomical forces. A new perspective was introduced when high and low frequencies were compared, leading to the comprehension that astronomical tides should be considered in coastal studies in southern Brazil. The sea level time series analyzed in this study showed that the maximum amplitude of the high spring tide was 0.53m, and that the subtidal rise caused by the wind reached up to 0.66m. In general, when large tidal and subtidal amplitudes are added, it can generate extreme events of sea level rise on the coast, which constitute a direct threat to coastal communities and habitats. [ABSTRACT FROM AUTHOR]

In this paper, subspace methods are applied to the identification of the dominant electromechanical oscillation modes of a large power system, using ambient data. The data are acquired by a low-voltage WAMS. Complementary techniques for the preprocessing of the measurements, and the tuning of the identification methods, are discussed. Results for the Brazilian Interconnected Power System are presented. [ABSTRACT FROM AUTHOR]

Abstract: Carbonate concretions are common features in arid and semi-arid climates. They can be formed under pedogenic conditions, developing complex profiles with or without biogenic contribution or in groundwater conditions, forming thick massive beds of carbonate. Together with other data, calcretes can be used as tools for paleoclimatic and paleoenvironmental interpretation. In Southern Brazil, the Triassic Santa Maria Supersequence (Sequences I and II) includes four types of calcretes with distinct modes of formation: a) precipitation of carbonate in the oscillation zone of the phreatic level, with posterior overlap of vadose and phreatic diagenetic processes; b) precipitation of pedogenic carbonate, forming crusts in the paleosol; c) precipitation of carbonate forming concentric concretions in the stable phreatic level; and d) preservation of root casts due to processes of precipitation in the oscillation zone of the phreatic level. The presence of silica minerals and barite in the concretions is attributed to seasonal changes in water table level. Due to the high evaporation rate in semi-arid climates, the most compatible process of formation of these calcretes is the per ascensum model. Integration of calcrete data with the sedimentological and paleontological framework allowed a refinement of paleoclimatic data, suggesting that, despite the scarcity of plant fossils, the Middle Triassic in Southern Brazil was vegetated with plants. [Copyright &y& Elsevier]

Abstract: An assumption of the existence of natural climatic oscillations driven by solar activity enables an explanation of phase differences between variations in solar activity and rainfall level in Fortaleza, Brazil. Decadal and interdecadal variations in rainfall level can be reproduced using a forced oscillation equation with a driving force term that describes the variation in the sunspot number and with the assumption of the existence of 31.7-year interdecadal and 12.96-year decadal natural climatic oscillations. This equation satisfactorily reproduces the periodicity with a length of approximately 22yr in the interdecadal rainfall variation before and up to the middle of the past century as well as the subsequent phase inversion, period and amplitude increase in the variation that followed the corresponding increases in the interdecadal sunspot number variation. The equation accurately reproduces the irregular phase shifts between decadal variations in rainfall level and in sunspot number over the entire 160yr of recorded observations. [Copyright &y& Elsevier]

This research is aimed to prove the influence of the preterits climatic oscillations on the determination of the origin and on the morphology of the current relief's sculpture and their implications on the evolution of the landscape. The techniques that were proposed integrate cartography and filed activities, with a methodology that suggests the relief develop in a polycyclic process conditioned by preterit climatic oscillations. The methodology is defined as Climatic Geomorphology. The observed area is located in the south-central region of the Parana State, in a paleogeographic landscape (relict) with special natural features identified as General Fieldland. The research characterized the geological, hydrographical and geomorphologic elements around the springs of the Tibagi's river. This drainage system, named in this paper as Highest Tibagi's Hydrographic Basin (HTHB), is located in the highest sector of entire hydrographic basin formed by Tibagi's river; covering an area of 72.93 km2. The maps for the characterization of the landscape were structured on: satellite images, topographic and geological charts in scale 1: 50,000. The elaborated thematic maps improve the understanding of the physiographic situation of the sector studied, and were prepared and developed by a geographic information system. Field activities and photographic documentation were developed in order to support the research. The research identified flat surfaces in the area of the study, which provide evidences of the climate oscillations influence on the sculpting of the relief. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an object-oriented framework to perform dynamical studies in electrical power systems. The proposed methodology is also useful to the development, upgrade and maintenance of software for power system studies. The framework was designed to be used by developers of power system software. Based on software engineering concepts, user''s requirements are, firstly, mapped to atomic classes which, in turn, are subsequently used to build state-space representation for each dynamic device in the power system under study, such as electrical generators, turbines and automatic controllers. The developed framework automates the whole process of building a global system model, providing a standard space-state model suitable for implementing by direct code in C++ language. By using the proposed methodology, a power system simulation tool was specially developed to study electromechanical phenomena observed at Tucuruí hydroelectric power plant, a large power plant of the Brazilian Interconnected Power System. The results were validated by comparing the simulated to the actual plant response obtained from field tests carried out at the Tucuruí power plant. The results have shown a very good level of performance of the developed simulator system. The simulator was able to reproduce the dominant dynamical phenomena observed at the Tucuruí power plant. [Copyright &y& Elsevier]

This study aimed at answering the question: do people with high bone loss have greater postural instability? Groups were separated into group 1: women with normal bone mineral density, group 2: women with osteopenia, and group 3: women with osteoporosis. The balance was evaluated in four upright postural situations. Osteoporosis group had greater oscillation in the anteroposterior displacement in all situations compared to control group and the greatest mediolateral displacement in all situations compared to other groups. It is not known whether the presence of osteoporosis can be considered a factor aggravating the postural control. This study aimed at answering the question: do people with high bone loss have greater postural instability? This study was divided into three groups: group 1 ( n = 20) consisting of women with normal bone mineral density, group 2 ( n = 20) women with osteopenia, and group 3 ( n = 20) women with osteoporosis. All the participants were submitted to evaluation of the balance using the Polhemus system in four upright postural situations. Osteoporosis group had greater oscillation in the anteroposterior displacement in all situations compared to control group. The osteoporosis group also showed the greatest mediolateral displacement in all situations compared to other groups. The results suggest that osteoporotic women had the worst balance, possibly due to the more pronounced body changes compared to non-osteoporotic women. [ABSTRACT FROM AUTHOR]

Cross-winds of relatively low velocities have been observed over the years to cause large amplitude vortex-induced oscillations of the Rio-Niterói bridge, the world's largest steel twin-box-girder bridge. These oscillations, which were recorded by the automatic long-term monitoring system and by video cameras installed on the bridge, revealed the existence of the lock-in phenomenon and hence the urgent need to attenuate the aeroelastic oscillations. To this end, a novel system of multiple synchronised dynamic attenuators has been installed in the central span of the bridge. A short account is given of how an experimentally calibrated mathematical-numerical model for the aeroelastic behaviour was used to assist in designing feasible mechanical control devices to upgrade the serviceability of this bridge and users' comfort. The conceptual design of the passive control system, together with its main geometric and physical characteristics, are briefly described herein. The efficiency of the control system is demonstrated through comparisons of numerical results obtained for time responses of the original and the controlled structure, and its good performance has been experimentally observed in the actual bridge. [ABSTRACT FROM AUTHOR]

The analysis of the interannual variability of the South American monsoon rainfall is carried out separately for austral spring and summer (and for November and January), based on a 40-yr station gauge dataset. Relationships between modes of variability in these seasons show the influence of antecedent conditions in spring (or November) on the evolution of the monsoon rainfall in peak summer (or January). In spring the first mode is dipolelike, with opposite loadings over central-eastern and southeastern South America. It is connected with ENSO. The second mode shows the highest loadings slightly south of the South Atlantic convergence zone. The leading mode of summer also features dipolelike oscillations between central-eastern and southeastern South America, but is not strongly connected with ENSO. The second mode represents the impact of ENSO, and the third is modulated by SST anomalies in the southern tropical Atlantic. Significant relationships are disclosed between the first dipolelike modes of spring and summer rainfall and thus between the rainfall in spring and summer over central-eastern South America, which includes part of the monsoon core region. These dipolelike modes are associated with a rotational anomaly over southeast Brazil that either conveys moisture flux into central-eastern Brazil (if it is cyclonic) or into southeastern South America (if it is anticyclonic). In spring this anomaly seems to be remotely forced, but after strong rainfall anomalies over central-eastern Brazil in spring, it tends to reverse sign in peak summer, inverting the dipolelike rainfall anomalies. This reversal is hypothesized to be locally forced by surface–atmosphere feedback triggered by the spring anomalies, as weaker teleconnections in summer allow local processes that are stronger in summer to overcome remote forcing. SST and circulation anomalies associated with the first modes in spring and summer, and also the relationship between the first summer mode and surface temperature in spring, are consistent with that hypothesis. [ABSTRACT FROM AUTHOR]

Highly redundant or statically undetermined structures, such as a cable-stayed bridge, have been of particular concern to the engineering community nowadays because of the complex parameters that must be taken into account for healthy monitoring. The purpose of this study was to verify the reliability and practicability of using GPS to characterize dynamic oscillations of small span bridges. The test was carried out on a cable-stayed wood footbridge at Escola de Engenharia de São Carlos-Universidade de São Paulo, Brazil. Initially a static load trial was carried out to get an idea of the deck amplitude and oscillation frequency. After that, a calibration trial was carried out by applying a well known oscillation on the rover antenna to check the environment detectable limits for the method used. Finally, a dynamic load trial was carried out by using GPS and a displacement transducer to measure the deck oscillation. The displacement transducer was used just to confirm the results obtained by the GPS. The results have shown that the frequencies and amplitude displacements obtained by the GPS are in good agreement with the displacement transducer responses. GPS can be used as a reliable tool to characterize the dynamic behavior of large structures such as cable-stayed footbridges undergoing dynamic loads. [ABSTRACT FROM AUTHOR]

Abstract: A series of tests with a model of a monocolumn platform with a moonpool were performed at the LabOceano/COPPE, at the Universidade Federal do Rio de Janeiro, with the objective of determining the entrance area at the bottom of the moonpool that minimizes vertical motion in waves. The tests include measurements of monocolumn surge, pitch and heave motion, vertical motion of the water column inside the moonpool, with different mooring systems, in regular, irregular and transient waves. This paper presents experimental results of the monocolumn vertical motion and the internal water column motion in the moonpool in transient waves and results of vertical motion of the water column inside the moonpool with the model held still in transient waves. These measurements allow an analysis of the impact of the moonpool''s bottom opening on the monocolumn vertical motion in waves. The theoretical analysis of a mass–spring–damper system with two degrees of freedom, similar to the studied system, has shown some analogy with den Hartog''s damped vibration absorber; however, there are significant differences in terms of added mass and coupled terms of added mass and damping coefficients dependent on oscillation frequencies. [Copyright &y& Elsevier]

The Patos Lagoon is a choked, microtidal coastal lagoon situated in southern Brazil between 30°S and 32°S. The response of the lagoon to tidal oscillations is studied through data analysis and numerical modeling experiments. Two types of high frequency oscillations are observed in the tidal frequency band: mixed tides, predominantly diurnal; and forced oscillations having a period of 24 h occurring in the inner lagoon. In the southern portion of the lagoon, tides are selectively filtered by the entrance channel. The main diurnal constituent O1 is linearly attenuated as it progresses landwards. In the inner parts of the lagoon, 24-h oscillations are mainly forced by the combined effect of diurnal tides and sea breeze action. They are tied with a natural period of oscillation of 24 h. Results also indicate that these are not inertial frequency oscillations, despite the lagoon being placed in a critical 30°S area. The interaction between astronomical tides and meteorological effects produces a complicated picture for tidal forecasting derived from data collected inside the lagoon. [ABSTRACT FROM AUTHOR]

Simulation coupling subsurface (reservoir) and surface (network) systems is a challenging problem, especially for computationally intensive multi-reservoir models and complex surface network facilities. Integration of petroleum systems can be done using different simulators (explicit coupling) or considering all individual components of the system in one simulator (implicit coupling). The explicit method is more flexible, allowing the integration of commercial-off-the-shelf simulators. However, as a drawback, it can yield oscillatory solutions. In this work, a new framework for mitigating explicit coupling numerical instabilities (oscillations) is developed by recasting the problem in a control setting. Results from this work show that explicit coupling without a mechanism to avoid numerical instabilities presents oscillations that can grow throughout the simulation. In order to mitigate the numerical oscillations we develop a framework based on a feedback control system, namely a PID (Proportional, Integral and Derivative) controller. The PID controller, with parameters ( K C , τ I , τ D) tuned manually for a group of well settings, adjusts the traditional IPR curve generated by the reservoir simulator so that the error between the bottom-hole pressure calculated by the reservoir simulator (B H P R S ) and the bottom-hole pressure defined in the operating point (B H P O P ) is minimal. In this case, a q O P value representative for the entire time step (next time step) is obtained. The new methodology was tested in a synthetic numerical model (UNISIM-I-D) based on Namorado field (Campos Basin – Brazil), comprised by 20 satellite wells (7 injectors and 13 producers). The PID control reduces the rate and pressure oscillations in the case study, and results converge with base case scenario, which represents the network system of producer wells by proper pressure drop tables. • Methodology can be used with any comercial-off-the-shelve simulator. • Improved oscillations in coupled surface-subsurface flows. • Explicit coupling allows for faster computational time. • PID controller can be added seamlessly to the simulator coupler. • Methodology applied to realistic reservoirs. [ABSTRACT FROM AUTHOR]

This study investigates historical fire regimes and arboreal cover variability in the Brazilian Cerrados, a large Neotropical savanna ecosystem, during the Pleistocene-Holocene transition and early Holocene, and then tests whether the observed variation is linked to South American Summer Monsoon (SASM) variability. We present high-resolution pollen, XRF and charcoal records from Lagoa Feia, located in central Cerrados, and assess how they compare with other pollen records from the surrounding region to investigate regional trends of vegetation and fire regime variability. Our results show that the Pleistocene-Holocene transition was marked by a wet episode, which included moist forest expansion and rising lake levels, that correlates well with increased monsoon activity in a large area of central South America during the same period. This wet episode chronologically coincides with the Younger Dryas cold episode in the northern hemisphere. Our data revealed moisture declines in central Cerrados after 11.2 kyr BP, along with centennial-scale fluctuations from dry to wet conditions throughout the early Holocene period until around 6 kyr BP. These dry/wet oscillations are associated with weakened SASM activity and repeated shifts of its belt position during this time range. Fire activity increased in central Cerrados just after the onset of drier conditions during the early Holocene, and likely contributed to decreased arboreal cover at that time. A trend of increasing moisture in the region was observed after 6 kyr BP. Our study reveals how centennial and millennial-scale changes in monsoon activity influenced arboreal cover, diversity and fire regimes in the central Cerrados. • Increased SASM activity in the Pleistocene-Holocene shift led to forest growth. • Centennial-scale dry/wet shifts in the early-middle Holocene were linked to SASM. • Dry conditions in the early Holocene increased fire activity in the Cerrados. [ABSTRACT FROM AUTHOR]

The stability of methane hydrates on continental margins worldwide is sensitive to changes in temperature and pressure conditions. It has been shown how gradual increases in bottom water temperatures due to ocean warming over post-glacial timescales can destabilize shallow oceanic hydrate deposits, causing their dissociation and gas release into the ocean. However, bottom water temperatures (BWT) may also vary significantly over much shorter timescales, including due to seasonal temperature oscillations of the ocean bottom currents. In this study, we investigate how a shallow methane hydrate deposit responds to seasonal BWT oscillations with an amplitude of up to 1.5 °C. We use the TOUGH + HYDRATE code to model changes in the methane hydrate stability zone (MHSZ) using data from the Rio Grande Cone, in the South Atlantic Ocean off the Brazilian coast. In all the cases studied, BWT oscillations resulted in significant gaseous methane fluxes into the ocean for up to 10 years, followed by a short period of small fluxes of gaseous methane into the ocean, until they stopped completely. On the other hand, aqueous methane was released into the ocean during the 100 years simulated, for all the cases studied. During the temperature oscillations, the MHSZ recedes continuously both horizontally and, in a smaller scale, vertically, until a permanent and a seasonal region in MHSZ are defined. Sensitivity tests were carried out for parameters of porosity, thermal conductivity and initial hydrate saturation, which were shown to play an important role on the volume of methane released into the ocean and on the time interval in which such release occurs. Overall, the results indicate that in a system with no gas recharge from the bottom, seasonal temperature oscillations alone cannot account for long-term gas release into the ocean. • Methane release from oceanic hydrates due to seasonal temperature variations mostly in the aqueous phase over 100 years. • Stability zone recedes downslope over time but most of it remains unaltered. • Methane release rate and stability zone changes sensitive to initial saturation, porosity and thermal conductivity. [ABSTRACT FROM AUTHOR]

Oscillations in the complementary cumulative distribution function (CCDF) of individual income data have been found in the data of various countries studied by different authors at different time periods, but the dynamical origins of this behavior are currently unknown. Although these datasets can be fitted by different functions at different income ranges, the Tsallis distribution has recently been found capable of fitting the whole distribution by means of only two parameters. This procedure showed clearly such oscillatory feature in the entire income range feature, but made it particularly visible at the tail of the distribution. Although log-periodic functions fitted to the data are capable of describing this behavior, a different approach to naturally disclose such oscillatory characteristics is to allow the Tsallis q -parameter to become complex. In this paper we use this idea in order to describe the behavior of the CCDF of the Brazilian personal income recently studied empirically by Soares et al. (2016). Typical elements of periodic motion, such as amplitude and angular frequency coupled to this income analysis, were obtained by means of this approach. A highly non-linear function for the CCDF was obtained through this methodology and a numerical test showed it capable of recovering the main oscillatory feature of the original CCDF of the personal income data of Brazil. • Income distribution analysis through Tsallis thermostatistical formalism. • Complexification of the q -parameter shows the oscillatory behavior. • The numerical example demonstrates that the q -complexification represents the empirical data. [ABSTRACT FROM AUTHOR]