A new method to determine the gravity field of small bodies from line-of-sight acceleration data

We present a new method to derive line-of-sight acceleration observables from spacecraft radio tracking data. The observables can be used to estimate the mass and gravity of a natural satellite as a spacecraft flyby. The corresponding observation model adapts to one-way and two/three-way tracking modes. As a test case for method validation and application, we estimated the mass and degree two gravity field for the Martian moon Phobos using simulated tracking data when the spacecraft Mars Express flew by Phobos on 2013 December 29. We have a few real tracking data during flyby and they will be used to confirm raw data simulation. The main purpose of this paper is to demonstrate the method of line-of-sight acceleration reduction from raw tracking data and the feasibility to estimate mass and gravity of a natural satellite using this type of observable. This novel method is potentially applicable to planet and asteroid gravity field studies combined with Doppler tracking data.

Dynamic Modelling of Dengue Epidemics in Function of Available Enthalpy and Rainfall

In this work, we present results of an investigation of environmental precursors of infectious epidemic of dengue fever in the Metropolitan Area of Rio de Janeiro, RJ, Brazil, obtained by a numerical model with representation of infection and reinfection of the population. The period considered extend between 2000 and 2011, in which it was possible to pair meteorological data and the reporting of dengue patients worsening. These data should also be considered in the numerical model, by assimilation, to obtain simulations of Dengue epidemics. The model contains compartments for the human population, for the vector Aedes aegypti and four virus serotypes. The results provide consistent evidence that worsening infection and disease outbreaks are due to the occurrence of environmental precursors, as the dynamics of the accumulation of water in the breeding and energy availability in the form of metabolic activation enthalpy during pre-epidemic periods.

The supernova remnant CTB 37B and its associated magnetar CXOU J171405.7-381031:evidence for a magnetar-driven remnant

We discuss the association between the candidate magnetar CXOU J171405.7-381031 and the supernova remnant CTB 37B.The recent detection of the period derivative of the object allowed an estimation of a young characteristic age of only ～ 1000yr.This value is too small to be compatible even with the minimum radius of the remnant being ≥ 10 pc,the value corresponding to the lower limit of the estimated distance of 10.2 ± 3.5 kpc,unless the true distance happens to be even smaller than the lower limit.We argue that a consistent scenario for the remnant＇s origin,in which the latter is powered by the energy injected by a young magnetar,is indeed more accurate to explain the young age,and demonstrates its non-standard（i.e.magnetar-driven） nature.

TOPMODEL Hydrometeorological Modeling with Rain Gauge Data Integrated by High-Resolution Satellite Estimates. A Case Study in MuriaéRiver Basin, Brazil

This study consists of hydrological simulations of the Muriaé river watershed with the topography-based hydrological model (TOPMODEL) and available stream gauge and rain measurements between 2009 and 2013 for two subbasins, namely Carangola and Patrocínio do Muriaé. The simulations were carried out with the Climate Prediction Center morphing method (CMORPH) precipitation estimates and rain gauge measurements integrated into CM- ORPH by the Statistical Objective Analysis Scheme (SOAS). TOPMODEL calibration was performed with the shuffled complex evolution (SCE-UA) method with Nash-Sutcliffe efficiency (NSE). The best overall results were obtained with CMORPH (NSE ~ 0.6) for both subbasins. The simulations with SOAS resulted in an NSE ~ 0.2. However, in an analysis of days with high- level stages, SOAS simulations resulted in a better hit rate (23%) compared to CMORPH (10%). CMORPH simulations underestimated the flows at the flood periods, which indicates the importance to use multi-sensor precipitation data. The results with TOPMODEL allow an estimate of future discharges, which allows for better planning of a flood warning system and discharge measurement schedule.

On Thunderstorm Microphysics under Urban Heat Island, Sea Breeze, and Cold Front Effects in the Metropolitan Area of São Paulo, Brazil

This work discusses issues related to the impact of urbanization on the microphysical processes of precipitating systems associated with synoptic, mesoscale, and local scale systems. Among the issues addressed is the impact of urban heat island (UHI) in São Paulo city center and urban densification (UD) in the Metropolitan Area of São Paulo (MASP) on the microphysical, dynamic, and thermodynamic properties and distribution of precipitation and heavier rainfall from sea-breeze (SB) e cold-front (CF) combined during their space-time evolutions. For this purpose, it used four components: classification of hydrometeors with fuzzy logic, calculation of the raindrop diameters, an estimate of liquid water mass and ice mass from polarimetric-variables measured with dual-pola- rization X-band meteorological radar. The results indicated that urban densification (UD) and heat island (UHI) of the São Paulo city center impact the formation of precipitation, liquid water mass, and ice mass, depth, and duration of a thunderstorm. It was also observed the asymmetric configuration of the thunderstorm is induced by the strong convergence in the São Paulo city center, and this strong convergence is induced by the intense heat island (UHI) in the São Paulo city center. Was also observed that this event that is formed in the Metropolitan Area of São Paulo (MASP) depends on microphysical processes of mixed-phase of the cloud (water and ice) above the 0°C isotherm for the production of intense rain and cold pool at the surface. These important microphysical processes within long-lasting secondary convective cells over the São Paulo city center should be taken into account on convective parameterization schemes as well as the associated cold pool dynamics.

Depth Estimates of Buried Utility Systems Using the GPR Method: Studies at the IAG/USP Geophysics Test Site

Identifying underground utilities and predicting their depth are fundamental when it comes to civil engineering excavations, for example, to install or repair water, sewer, gas, electric systems and others. The accidental rupture of these systems can lead to unplanned repair costs, delays in completing the service, and risk injury or death of workers. One way to detect underground utilities is using the GPR-Ground Penetrating Radar geophysical method. To estimate depth, the travel time (two-way travel time) information provided by a radargram is used in conjunction with ground wave velocity, which depends on the dielectric constant of materials, where it is usually assumed to be constant for the area under investigation. This procedure provides satisfactory results in most cases. However, wrong depth estimates can result in damage to public utilities, rupturing pipes, cutting lines and so on. These cases occur mainly in areas that have a marked variation of water content and/or soil lithology, thus greater care is required to determine the depth of the targets. The present work demonstrates how the interval velocity of Dix (1955) can be applied in radargram to estimate the depth of underground utilities compared to the conventional technique of constant velocity applied to the same data set. To accomplish this, synthetic and real GPR data were used to verify the applicability of the interval velocity technique and to determine the accuracy of the depth estimates obtained. The studies were carried out at the IAG/USP test site, a controlled environment, where metallic drums are buried in known positions and depths allowing the comparison of real to estimated depths. Numerical studies were also carried out aiming to simulate the real environment with variation of dielectric constant in depth and to validate the results with real data. The results showed that the depths of the targets were estimated more accurately by means of the interval velocity technique in contrast to the constant velocity technique, minimizing the risks of accidents during excavation.

A triplet of the only pulsation mode detected in the DAV star G132–12

Hydrogen atmosphere pulsating white dwarfs,also known as DAV stars,are the most abundant type of pulsating white dwarfs.High-temperature DAV stars in general exhibit a small number of pulsation modes and stable frequencies.G132-12 is one of the pulsating hydrogen atmosphere white dwarf stars which lies close to the blue edge of the instability strip.Previous researches reported that G132-12 might have only one pulsation mode with the period of 212.69 s.To study the pulsation properties of G132-12 in detail,we carried out a bi-site observation campaign in October 2019.Time series photometric data were collected during around 154 h in total.A Fourier analysis reveals three frequencies which are identified as the triplet of an l=1 g-mode pulsation with the period of 212.499 s.The rotational period is derived as Prot=35.0±6.7 h and the inclination of the rotational axis to the line of sight is 70°.G132-12 could be an ideal target for measuring the cooling scale of this white dwarf star with only one excited pulsation mode detected.

2D TEM Modeling for a Hydrogeological Study in the ParanáSedimentary Basin, Brazil

This work uses 2D TEM (Transient Electromagnetic) modeling for a hydrogeological study in the Paraná sedimentary basin. The study area is located at the northern region of the state of S?o Paulo, Brazil, where groundwater is exploited from two aquifer systems: one sedimentary, shallow, and the other crystalline, deep. The interest in applying the TEM method in this area owes to the high exploitation rates of groundwater from the crystalline aquifer system for irrigation, which is triggering considerable seismic activity locally. This aquifer system is composed of fractured basalt within the Serra Geral Formation and is about 120 m deep. Eighty-six TEM soundings were acquired at this location, but in nine cases the data did not fit the modelled curve for 1D geoelectrical models due to the geological complexity of the area. This paper shows 2D geoelectrical modeling results based on the FDTD (Finite Differences in Time Domain) method to explain the lateral resistivity variation within the geological setting. A 2D model was generated for each sounding and compared with 1D inversion models as well as with direct information from wells. The results show some vertical variations of about 10 to 30 meters on the upper interface of the basalt layer from Serra Geral Formation. They are located at approximately 60 meters from the center of the soundings. The existence of these 2D structures in the subsurface can be related to the drainage system in the study area. The presence of these structures may indicate a connection between the shallow and deep aquifer systems, acting like a conduit that may contribute to the seismic activity reported.

Electrical Resistivity Tomography and TDEM Applied to Hydrogeological Study in TaubatéBasin, Brazil

This research applies Electrical Resistivity Tomography (ERT) and Time Domain Electromagnetic Method (TDEM) to study the hydrogeology of the Taubaté basin, which is characterized by half-grabens with about 850 m of maximum sediments thickness. The study area is in Taubaté city, São Paulo State, Brazil, where the Taubaté aquifer is an important water source. The Taubaté Group is the main sedimentary package of the basin;it is formed mainly by shales that form aquicludes, and thin layers of sandstones that form the aquifer. There are 40 groundwater exploration wells in Taubaté city that provide important information. The study purpose is to characterize the geoelectrical stratigraphy of the subsurface to locate the contact between the Quaternary and Tertiary sediments and to identify the Taubaté aquifer. The ERT is used for shallow investigations (tens of meters) and the TDEM can reach a great investigation depth (hundreds of meters). Therefore, these geophysical methods are complementary. The ERT data were acquired with the pole-dipole array with 20 m of electrodes spacing and 400 m length, and the TDEM data with the central-loop array with a 200 × 200 m transmitter loop. The results permit to define the contact between the Quaternary and Tertiary sediments around 15 m depth, the Pindamonhangaba Formation between 15 m and 30 m depth and the Taubate Group between 30 m and 300 m depth. The TDEM method defined the Taubaté Group as a single geoelectric layer because the shale and the sandstone layers are all very conductive. The basement is formed by gneiss, which is a very resistive rock. The TDEM method is not able to identify a high conductor/resistor contrast. Overall, the results are consistent with the known geology and the wells information.

Unraveling one billion years of geological evolution of the southeastern Amazonia Craton from detrital zircon analyses

Despite representing one of the largest cratons on Earth,the early geological evolution of the Amazonia Craton remains poorly known due to relatively poor exposure and because younger metamorphic and tectonic events have obscured initial information.In this study,we investigated the sedimentary archives of the Carajás Basin to unravel the early geological evolution of the southeastern Amazonia Craton.The Carajás Basin contains sedimentary rocks that were deposited throughout a long period spanning more than one billion years from the Mesoarchean to the Paleoproterozoic.The oldest archives preserved in this basin consist of a few ca.3.6 Ga detrital zircon grains showing that the geological roots of the Amazonia Craton were already formed by the Eoarchean.During the Paleoarchean or the early Mesoarchean(<3.1 Ga),the Carajás Basin was large and rigid enough to sustain the formation and preservation of the Rio Novo Group greenstone belt.Later,during the Neoarchean,at ca.2.7 Ga,the southeastern Amazonia Craton witnessed the emplacement of the Parauapebas Large Igneous Province(LIP)that probably covered a large part of the craton and was associated with the deposition of some of the world largest iron formations.The emplacement of this LIP immediately preceded a period of continental extension that formed a rift infilled first by iron formations followed by terrigenous sediments.This major change of sedimentary regime might have been controlled by the regional tectonic evolution of the Amazonia Craton and its emergence above sea-level.During the Paleoproterozoic,at ca.2.1 Ga,the Rio Fresco Group,consisting of terrigenous sediments from the interior of the Amazonia Craton,was deposited in the Carajás Basin.At that time,the Amazonian lithosphere could have either underwent thermal subsidence forming a large intracratonic basin or could have been deformed by long wavelength flexures that induced the formation of basins and swells throughout the craton under the influence of the growing Transamazonian mountain belt.

Multi-planet extrasolar systems-detection and dynamics

20 years after the discovery of the first planets outside our solar system, the current exoplanetary population includes more than 700 confirmed planets around main sequence stars. Approximately 50% belong to multiple-planet systems in very diverse dynamical configurations, from two-planet hierarchical systems to multiple resonances that could only have been attained as the consequence of a smooth large- scale orbital migration. The first part of this paper reviews the main detection tech- niques employed for the detection and orbital characterization of multiple-planet sys- tems, from the （now） classical radial velocity （RV） method to the use of transit time variations （TTV） for the identification of additional planetary bodies orbiting the same star. In the second part we discuss the dynamical evolution of multi-planet systems due to their mutual gravitational interactions. We analyze possible modes of motion for hi- erarchical, secular or resonant configurations, and what stability criteria can be defined in each case. In some cases, the dynamics can be well approximated by simple ana- lytical expressions for the Hamiltonian function, while other configurations can only be studied with semi-analytical or numerical tools. In particular, we show how mean- motion resonances can generate complex structures in the phase space where different libration islands and circulation domains are separated by chaotic layers. In all cases we use real exoplanetary systems as working examples.

Dengue Climate Variability in Rio de Janeiro City with Cross-Wavelet Transform

Dengue is one of the most prominent tropical epidemic diseases present in the Rio de Janeiro city and Southeast part of Brazil, due to the widespread conditions of occurrence of the dengue vector, the mosquito Aedesaegypti, such as high-temperature days interlaced with afternoon or nocturnal rainstorms in summer. This work has the objective of investigating the relationships between variabilities of the El Ni?o-South Oscillation (ENSO) and greater epidemics of dengue in Rio de Janeiro city. To accomplish this goal, the analysis and signal decomposition by cross-wavelet transform (WT) was applied to obtain the cross variability associated with variations of power and phase of both signals by characteristic periods and along with the time series. Data considered in the analysis are (the decimal logarithm of normalized value) of the monthly available notifications of dengue worsening, provided by the public health system of Brazil, and the Southern Oscillation Index (SOI) Ni?o 3.4 data, provided by the National Oceanic and Atmospheric Administration (NOAA), in the period 2000-2017. A maximum cross-wavelet power close to 0.45 was obtained for the representative period of 1 year and also to periods between 3 and 4 years, associated with the positive phase of the SOI index (i.e. , La Ni?a) or with a transition to the positive phase. The evolution of the combined variability of SOI and dengue can be expressed by progressive differences in phase along the time, eventually resulting in yielding phases (i.e., La Niña-Dengue epidemic).

First photometric study of ultrashort-period contact binary 1SWASP J140533.33＋114639.1

In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33＋114639.1（hereafter J1405） in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney（W-D） code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the（O-C） method,the variation of orbital period is studied using all the available times of minimum light. The（O-C） diagram reveals that the period is increasing continuously at a rate of d P/dt = ＋2.09×10^-7 d yr^-1,which can be explained by mass transfer from the less massive component to the more massive one.

盾牌δ型变星HD213534的多重频率

本文利用三国联合观测获得的大量高精度光电测光数据,采用Fourier周期分析的方法,得到了δScuti型变星HD213534的多重脉动周期,认为该星存在五个以上的脉动频率.文中给出了该星的各项参量,并对其脉动模式进行了讨论,认为HD213534星是一颗以非径向脉动为主的多重周期脉动变星.

Hydrometeorology of Anthropogenic Erosion in the Metropolitan Region of São Paulo

Erosive processes play an important role in environmental degradation. Rain is the main erosive agent in the Metropolitan Region of Sao Paulo. This study characterized the erosion events caused by precipitation leveraging the accumulated daily precipitation estimate generated by the Climate Prediction Center Morphing Method (CMORPH) and integrating the surface telemetric network using the Statistical Objective Analysis method (SOAS). From the Civil Defense database, 400 events were identified in the Metropolitan region of Sao Paulo (MRSP) area between 2000 and 2013 and, of these, 3 were chosen to carry out meteorological and climatological analyses. In an initial observation, 58% of them were found to occur in summer. Two regions with the highest number of erosion events were observed, in the Serra do Mar and Serra da Cantareira. In the Serra do Mar core, the municipality of São Bernardo do Campo was the one with the greatest amount of erosion. Precipitation volumes were estimated for accumulations of 30 minutes, 1 day, 1 month, and 1 year. The results, from the 3 events, indicate accumulated precipitation in 30 minutes from 10 mm to 19.8 mm, daily from 30.8 mm to 69.5 mm, and 1 month from 369.7 mm to 742.5 mm, and 1 year (2010) from 1712.9 mm to 1961.8 mm. In these events, it was noted that there were heavy rains in December 2009 and January 2010. It was also noted that the CMORPH and SOAS identify the rain events found by the São Paulo meteorological radar. The meteorological analyzes of the events based on images from the São Paulo meteorological radar and the Meteosat-9 satellite indicate that the active precipitation systems are associated with cold fronts, instability lines, and isolated convection.

Convective Rainfall in Lake Victoria Watershed and Adjacent Equatorial Africa

An integrated satellite precipitation estimation dataset, namely, the Climate Prediction Center morphing method (CMORPH), was used to analyze precipitation regimes across Equatorial Africa between 3°S - 1°N and 24°E - 42°E from 2000 to 2014. This region includes the Rift Valley, part of the Congo Forest, and the Lake Victoria (LV) basin, the second largest lake in the area of the world. Hovmöller diagrams were obtained for all organized convective systems to estimate their spans, duration, and phase speeds. The analysis included 33,189 episodes of westward propagating convective systems. Within the study area, lake and land breezes tend to trigger convection and precipitation over LV as well as mountain-valley circulation trigger thunderstorms over the mountains east of LV and western Rift Valley. The statistics of convective systems streaks on longitude-time diagrams were obtained for yearly frequencies of starting and ending longitudes and times among other morphologic variables. Results indicate organized precipitation episodes tend to move westward across Rift valley and Congo forest with an average phase speed of 10.3 m·s-1. More than 50% of them are triggered over LV and propagate more than 600 km at an average phase speed of 12.1 m·s-1. These convective systems tend to produce high rainfall rates hundreds of kilometers away into the Congo Forest. Half of all episodes of organized convection analyzed have phase speeds between 8 m·s-1 and 16 m·s-1, lasting 8 hr to 16 hr. Most precipitating systems start east of LV and west of Rift Valley in the afternoon to early morning and propagates less than 400 km. Finally, hourly precipitation accumulation and lightning density analysis indicate three preferable regions for convective initiation: 1) The mountain range east of LV;2) Midwest of LV, and;3) The Congo Forest mountain range.

The Effects of Negative Values of Apparent Resistivity in TEM Surveys

The calculation of apparent resistivity in electrical methods is relatively simple and consolidated in the literature. Furthermore, in the case of DC methods, the apparent resistivity values are for the most part, intuitive and enable an initial interpretation of the results. On the other hand, in TEM method the apparent resistivity values are not very intuitive and interpretation based only on the apparent resistivity values cannot be done reasonably. In this way, this paper presents a discussion about the reasons and effects of the negatives values of apparent resistivity in TEM soundings. The main objective of this paper is to clarify the meanings of these negatives values and the possible effects in TEM inversion.

Photometric light curve solutions of three ultra-short period eclipsing binaries

We present the results of our study of the eclipsing binary systems CSS J112237.1+395219,LINEAR 1286561 and LINEAR 2602707 based on new CCD B,V,Rcand Iccomplete light curves.The ultra-short period nature of these stars,as reported by Drake et al.,is confirmed and the system’s periods are revised.The light curves were modeled using the 2003 version of the Wilson-Devinney code.When necessary,cool spots on the surface of the primary component were introduced to account for asymmetries in the light curves.As a result,we found that CSS J112237.1+395219 is a W UMa type contact binary system belonging to W subclass with a mass ratio of q=1.61 and a shallow degree of contact of 14.8%where the primary component is hotter than the secondary one by 500 K.LINEAR 1286561 and LINEAR2602707 are detached binary systems with mass ratios q=3.467 and q=0.987 respectively.These detached systems are low-mass M-type eclipsing binaries with similar temperatures.The marginal contact,fill-out factor and temperature difference between components of CSS J112237.1+395219 suggest that this system may be at a key evolutionary state predicted by thermal relaxation oscillation(TRO)theory.From the estimated absolute parameters,we conclude that our systems share common properties with other ultrashort period binaries.

Trends of stellar entropy along stellar evolution

This paper is devoted to discussing the difference in the thermodynamic entropy budget per baryon in each type of stellar object found in the Universe. We track and discuss the actual decrease of the stored baryonic thermodynamic entropy from the most primitive molecular cloud up to the final fate of matter in black holes, passing through evolved states of matter as found in white dwarfs and neutron stars. We then discuss the case of actual stars with different masses throughout their evolution, clarifying the role of the virial equilibrium condition for the decrease in entropy and related issues. Finally, we discuss the role of gravity in driving the composition and the structural changes of stars with different Main Sequence masses during their evolution up to the final product. Particularly, we discuss the entropy of a black hole in this context arguing that the dramatic increase in its entropy, differently from the other cases, is due to the gravitational field itself.

Photometric and Spectroscopic Studies for Two Magnetic-activity Contact Binaries:V724 And and QR Com

We presented new CCD photometry for two contact binaries,V724 And and QR Com,which were observed during the 2020–2022 observing seasons.By using the Wilson–Devinney method,the photometric solutions were deduced from new observed data and TESS ones.Their asymmetric light curves were modeled by a dark spot on the more massive component.Results indicate that the starspot may immigrate or disappear on the surface of the active component.From the TESS observations of QR Com,it is discovered that the difference between light maxima exhibits a 29.5 day oscillation,which implies the continuous evolution of spot feathers on the timescale of several weeks.Their mass ratio and fill-out factor are q=2.308 and f=11.55% for V724 And,and q=0.624 and f=12.77% for QR Com,respectively.From the(O-C)curve,the orbital period secularly decrease at a rate of d P/dt=-1.66×10^(-7)day yr^(-1)for V724 And and d P/dt=-3.98×10^(-7)day yr^(-1)for QR Com,which was interpreted by mass transfer from the more massive component to the less massive one.With period decreasing,this kind of shallow-contact binaries,V724 And and QR Com,will evolve into the deep-contact configurations.