The location of lightning affecting the ionospheric sporadic-E layer as evidence for multiple enhancement mechanisms

We present a study of the geographic location of lightning affecting the ionospheric sporadic-E (Es) layer over the ionospheric monitoring station at Chilton, UK. Data from the UK Met Office's Arrival Time Difference (ATD) lightning detection system were used to locate lightning strokes in the vicinity of the ionospheric monitoring station. A superposed epoch study of this data has previously revealed an enhancement in the Es layer caused by lightning within 200km of Chilton. In the current paper, we use the same data to investigate the location of the lightning strokes which have the largest effect on the Es layer above Chilton. We find that there are several locations where the effect of lightning on the ionosphere is most significant statistically, each producing different ionospheric responses. We interpret this as evidence that there is more than one mechanism combining to produce the previously observed enhancement in the ionosphere.

Fast northward energy transfer in the Atlantic due to Agulhas rings

The adiabatic transit time of wave energy radiated by an Agulhas ring released in the South Atlantic Ocean to the North Atlantic Ocean is investigated in a two-layer ocean model. Of particular interest is the arrival time of baroclinic energy in the northern part of the Atlantic, because it is related to variations in the meridional overturning circulation. The influence of the Mid-Atlantic Ridge is also studied, because it allows for the conversion from barotropic to baroclinic wave energy and the generation of topographic waves. Barotropic energy from the ring is present in the northern part of the model basin within 10 days. From that time, the barotropic energy keeps rising to attain a maximum 500 days after initiation. This is independent of the presence or absence of a ridge in the model basin. Without a ridge in the model, the travel time of the baroclinic signal is 1300 days. This time is similar to the transit time of the ring from the eastern to the western coast of the model basin. In the presence of the ridge, the baroclinic signal arrives in the northern part of the model basin after approximately 10 days, which is the same time scale as that of the barotropic signal. It is apparent that the ridge can facilitate the energy conversion from barotropic to baroclinic waves and the slow baroclinic adjustment can be bypassed. The meridional overturning circulation, parameterized in two ways as either a purely barotropic or a purely baroclinic phenomenon, also responds after 1300 days. The ring temporarily increases the overturning strength. Th presence of the ridge does not alter the time scales.

Geiger tube coincidence counter for lower atmosphere radiosonde measurements

Atmospheric profiles of cosmic rays and radioactivity can be obtained using adapted meteorologi- cal radiosondes, for which Geiger tubes remain widely used detectors. Simultaneous triggering of two tubes provides an indication of energetic events. As, however, only small volume detectors can be carried, the event rate is small, which, due to the rapid balloon ascent, cannot be circumvented using long averaging periods. To derive count rates at low altitudes, a microcontroller is used to de- termine the inter-event time. This yields estimates of the coincidence rate below 5 km, where the coincidence rate is too small to determine solely by event counting

Heliospheric Observations of STEREO-Directed Coronal Mass Ejections in 2008 – 2010: Lessons for Future Observations of Earth-Directed CMEs

We present a study of coronal mass ejections (CMEs) which impacted one of the STEREO spacecraft between January 2008 and early 2010. We focus our study on 20 CMEs which were observed remotely by the Heliospheric Imagers (HIs) onboard the other STEREO spacecraft up to large heliocentric distances. We compare the predictions of the Fixed-Φ and Harmonic Mean (HM) fitting methods, which only differ by the assumed geometry of the CME. It is possible to use these techniques to determine from remote-sensing observations the CME direction of propagation, arrival time and final speed which are compared to in-situ measurements. We find evidence that for large viewing angles, the HM fitting method predicts the CME direction better. However, this may be due to the fact that only wide CMEs can be successfully observed when the CME propagates more than 100∘ from the observing spacecraft. Overall eight CMEs, originating from behind the limb as seen by one of the STEREO spacecraft can be tracked and their arrival time at the other STEREO spacecraft can be successfully predicted. This includes CMEs, such as the events on 4 December 2009 and 9 April 2010, which were viewed 130∘ away from their direction of propagation. Therefore, we predict that some Earth-directed CMEs will be observed by the HIs until early 2013, when the separation between Earth and one of the STEREO spacecraft will be similar to the separation of the two STEREO spacecraft in 2009 – 2010.

Evidence for solar wind modulation of lightning

The response of lightning rates over Europe to arrival of high speed solar wind streams at Earth is investigated using a superposed epoch analysis. Fast solar wind stream arrival is determined from modulation of the solar wind V y component, measured by the Advanced Composition Explorer spacecraft. Lightning rate changes around these event times are determined from the very low frequency arrival time difference (ATD) system of the UK Met Office. Arrival of high speed streams at Earth is found to be preceded by a decrease in total solar irradiance and an increase in sunspot number and Mg II emissions. These are consistent with the high speed stream's source being co-located with an active region appearing on the Eastern solar limb and rotating at the 27 d period of the Sun. Arrival of the high speed stream at Earth also coincides with a small (~1%) but rapid decrease in galactic cosmic ray flux, a moderate (~6%) increase in lower energy solar energetic protons (SEPs), and a substantial, statistically significant increase in lightning rates. These changes persist for around 40 d in all three quantities. The lightning rate increase is corroborated by an increase in the total number of thunder days observed by UK Met stations, again persisting for around 40 d after the arrival of a high speed solar wind stream. This result appears to contradict earlier studies that found an anti-correlation between sunspot number and thunder days over solar cycle timescales. The increase in lightning rates and thunder days that we observe coincides with an increased flux of SEPs which, while not being detected at ground level, nevertheless penetrate the atmosphere to tropospheric altitudes. This effect could be further amplified by an increase in mean lightning stroke intensity that brings more strokes above the detection threshold of the ATD system. In order to remove any potential seasonal bias the analysis was repeated for daily solar wind triggers occurring during the summer months (June to August). Though this reduced the number of solar wind triggers to 32, the response in both lightning and thunder day data remained statistically significant. This modulation of lightning by regular and predictable solar wind events may be beneficial to medium range forecasting of hazardous weather.

Upper-mantle seismic structure beneath SE and Central Brazil from P- and S-wave regional traveltime tomography

We present models for the upper-mantle velocity structure beneath SE and Central Brazil using independent tomographic inversions of P- and S-wave relative arrival-time residuals (including core phases) from teleseismic earthquakes. The events were recorded by a total of 92 stations deployed through different projects, institutions and time periods during the years 1992-2004. Our results show correlations with the main tectonic structures and reveal new anomalies not yet observed in previous works. All interpretations are based on robust anomalies, which appear in the different inversions for P-and S-waves. The resolution is variable through our study volume and has been analyzed through different theoretical test inversions. High-velocity anomalies are observed in the western portion of the Sao Francisco Craton, supporting the hypothesis that this Craton was part of a major Neoproterozoic plate (San Franciscan Plate). Low-velocity anomalies beneath the Tocantins Province (mainly fold belts between the Amazon and Sao Francisco Cratons) are interpreted as due to lithospheric thinning, which is consistent with the good correlation between intraplate seismicity and low-velocity anomalies in this region. Our results show that the basement of the Parana Basin is formed by several blocks, separated by suture zones, according to model of Milani & Ramos. The slab of the Nazca Plate can be observed as a high-velocity anomaly beneath the Parana Basin, between the depths of 700 and 1200 km. Further, we confirm the low-velocity anomaly in the NE area of the Parana Basin which has been interpreted by VanDecar et al. as a fossil conduct of the Tristan da Cunha Plume related to the Parana flood basalt eruptions during the opening of the South Atlantic.

Image processing technique to count the number of logs in a timber truck

This paper summarises the results of using image processing technique to get information about the load of timber trucks before their arrival using digital images or geo tagged images. Once the images are captured and sent to sawmill by drivers from forest, we can predict their arrival time using geo tagged coordinates, count the number of (timber) logs piled up in a truck, identify their type and calculate their diameter. With this information we can schedule and prioritise the inflow and unloading of trucks in the light of production schedules and raw material stocks available at the sawmill yard. It is important to keep all the actors in a supply chain integrated coordinated, so that optimal working routines can be reached in the sawmill yard.   

Avaliação dos impactos de uma proposta de escalonamento de horários em um campus universitário

O trabalho apresenta uma avaliação dos prováveis impactos do escalonamento dos horários das aulas noturnas em uma Universidade. Neste trabalho foi investigada, a preferência dos usuários quanto às possíveis alterações nos horários de entrada de aulas, e os impactos do escalonamento na rede viária no entorno do campus. O trabalho envolveu a construção de diversos cenários de alterações nos horários de início das aulas. Os cenários foram construídos visando atender as preferências da população universitária e reduzir a interferência do pico de chegada de alunos no sistema viário. A avaliação dos impactos destes cenários no tráfego foi realizada através de simulação, com a utilização do modelo TSIS/NETSIM. As análises foram baseadas em dois indicadores de desempenho: a velocidade média e o tempo de atraso médio na rede.

Assessment of Gastrointestinal Motility in Renal Transplant Recipients by Alternate Current Biosusceptometry

Background. Gastrointestinal (GI) complications are common after renal transplantation, mainly owing to immunosuppressive therapy. Assessment of GI transit time can facilitate rational management of these disorders.Objective. We evaluate the GI transit parameters in renal transplant recipients taking tacrolimus, azathioprine, and prednisone with the use of the alternate current biosusceptometry (ACB) technique and compared them with healthy volunteers.Methods. Ten renal transplant recipients and 10 healthy volunteers were enrolled in this study. After an overnight fast, patients and volunteers ingested a standard meal containing magnetic markers. The biomagnetic monitoring was performed at 10-minute intervals for at least 8 hours to obtain gastric emptying as well as the colonic arrival time-intensity curves. Mean gastric emptying time (MGET), mean colon arrival time (MCAT), and mean small intestinal transit time (MSITT) were quantified and compared between control and patient groups with results expressed as mean +/- SD.Results. The MGET measured by the ACB technique was 48 +/- 31 minutes and 197 +/- 50 minutes for patients and healthy subjects, respectively. MSITT and MCAT values calculated for patients versus volunteers were 171 +/- 71 minutes versus 197 +/- 71 minutes and 219 +/- 83 minutes versus 373 +/- 52 minutes, respectively. Renal transplant recipients showed significantly faster; gastric emptying and colon arrival times (P < .001) compared with normal volunteers; however, small intestinal transit time was not significantly different (P = .44).Conclusions. In stable renal transplant recipients, the GI transit parameters were significantly faster than in normal healthy volunteers. ACB sensors are versatile technologies that can be used for clinical research, because they offer an excellent opportunity to evaluate GI transit in a noninvasive manner without the use of ionizing radiation.

Performance of the CMS drift-tube chamber local trigger with cosmic rays

The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams. © 2010 IOP Publishing Ltd and SISSA.

Fine synchronization of the CMS muon drift-tube local trigger using cosmic rays

The CMS experiment uses self-triggering arrays of drift tubes in the barrel muon trigger to perform the identification of the correct bunch crossing. The identification is unique only if the trigger chain is correctly synchronized. In this paper, the synchronization performed during an extended cosmic ray run is described and the results are reported. The random arrival time of cosmic ray muons allowed several synchronization aspects to be studied and a simple method for the fine synchronization of the Drift Tube Local Trigger at LHC to be developed. © 2010 IOP Publishing Ltd and SISSA.

Estudo de propagação de ondas em planície de inundação para elaboração de plano de ação emergencial de barragens: UHE Três irmãos estudo de caso

Pós-graduação em Engenharia Civil - FEIS

Methods and results of a search for gravitational waves associated with gamma-ray bursts using the GEO 600, LIGO, and Virgo detectors

In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz-1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of O(10) for GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localization of GRBs detected by the GBM, if a high-frequency GW signal is observed in coincidence. We use the method of the linear grid in a search for GWs associated with 129 GRBs observed satellite-based gamma-ray experiments between 2006 and 2011. The GRBs in our sample had not been previously analyzed for GW counterparts. A fraction of our GRB events are analyzed using data from GEO 600 while the detector was using squeezed-light states to improve its sensitivity; this is the first search for GWs using data from a squeezed-light interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, under an assumption of a fixed GW emission energy of 10(-2)M circle dot c(2), with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events once the advanced LIGO and Virgo detectors begin operation.

Biosusceptometria de corrente alternada para avaliação do trânsito gastrintestinal de alimentos líquidos em ratos

The gastrointestinal tract is the main route of nutrients absorption and drugs delivery. Is important to know the parameters related to the tract, like gastric emptying and gastrointestinal transit, in order to better understand the behavior of different kind of meals or drugs passing through the GIT. Many techniques are used to study these parameters, such as manometry, scintigraphy, phenol red, activated charcoal and carbon-13 reading. However, these methods use radiation, are invasive and require animal sacrifice. As an alternative proposal, the Alternate Current Biosusceptometry (ACB), a magnetic technique, has proved to be effective for these studies with small animals, in a noninvasive way, low cost, radiation free and avoiding the animal death. Associating the ACB to magnetic micro or nanoparticles used as tracers, it is possible to observe the meal behavior inside of the GIT. Focusing meanly on liquid meals digestion, this paper had the objective to evaluate the efficiency of the ACB technique in gastric emptying and gastrointestinal transit evaluation of liquid meals in rats. To perform the experiments, magnetic nanoparticles (ferrite, MgFe2O4) were used on a 1,5 ml solution introduced by gavage on similar weight and age rats. The sensor made by 2 pairs of coils, capable of generating and detecting magnetic fields, creates a field on the interest place and when this field is in contact with the marked meal, it changes, resulting on a variation of the measured voltage. The voltage variation is analyzed and is obtained a particle concentration on the interest region. The results showed that is possible to apply the ACB technique on the GIT evaluation of liquid particles digestion, gastric emptying and meal cecum arrival time curves were obtained and from that, is possible to observe a pattern of gastrointestinal transit. Both mean process time values were acquired, proving the technique capability of ...

Aplicação do sistema de biosusceptometria AC para monitoramento de nanopartículas magnéticas na circulação sanguínea

Pós-graduação em Biologia Geral e Aplicada - IBB