The geographical distribution and socioeconomic risk factors of COVID-19, tuberculosis and leprosy in Fortaleza, Brazil

Background: Fortaleza (Brazil) is high endemic for coronavirus disease 2019 (COVID-19), tuberculosis (TB) and leprosy. These three diseases share respiratory droplets through coughing or sneezing as the main mode of transmission but differ in incubation time, with COVID-19 having a short and leprosy a long incubation time. Consequently, contacts of a patient are at higher risk of infection and developing these diseases. There might be scope for combined preventive measures, but a better understanding of the geographical distribution and relevant socioeconomic risk factors of the three diseases is needed first. This study aims to describe the geographic distribution of COVID-19, TB and leprosy incidence and to identify common socioeconomic risk factors. Methods: The total number of new cases of COVID-19, TB and leprosy, as well as socioeconomic and demographic variables, were retrieved from official registers. The geographical distribution of COVID-19, TB and leprosy rates per neighbourhood was visualised in Quantum GIS, and spatial autocorrelation was measured with Moran’s I in GeoDa. A spatial regression model was applied to understand the association between COVID-19, TB, leprosy rates, and socioeconomic factors. Results: COVID-19 and TB showed a more homogenous distribution, whereas leprosy is located more in the south and west of Fortaleza. One neighbourhood (Pedras) in the southeast was identified as high endemic for all three diseases. Literacy was a socioeconomic risk factor for all three diseases: a high literacy rate increases the risk of COVID-19, and a low literacy rate (i.e., illiteracy) increases the risk of TB and leprosy. In addition, high income was associated with COVID-19, while low income with TB. Conclusions: Despite the similar mode of transmission, COVID-19, TB and leprosy show a different distribution of cases in Fortaleza. In addition, associated risk factors are related to wealth in COVID-19 and to poverty in TB and leprosy. These findings may support policymakers in developing (partially combined) primary and secondary prevention considering the efficient use of resources.</p

NDE Applications of Radio Wave Emission from Stress and Fracture

It is well-known [1], [2] that when materials are fractured, substantial local electric fields are generated. These fields are capable of accelerating charged particles from the nascent interfaces, giving rise to a class of phenomena known as “exo-emission” or “fracto-emission”. The released “exo-particles”, consisting of electrons, ions, and charged clusters or fragments, can be collected and analyzed directly. Usually, such experiments are performed under conditions of high or ultra-high vacuum. This type of particle emission has been extensively studied previously, most notably by Dickinson and his co-workers [2] — [7]. Except for previous studies of fracturing rock, performed in connection with early-warning detection of earthquakes [8], [9], and the work of Dickinson, little has been done to characterize the radio wave emission that attends material fractures. Furthermore, no previous studies of radio wave emission from the elastically or plastically strained materials have been reported. Early qualitative studies of the visible light and radio wave emission from delaminating layers of adhesively bonded polymers and metals were reported by Derjagun and his co-workers. Emission during deformation suggests itself as a possible method for diagnosing the state of dynamic material strain in situations where contact methods are not feasible or are undesirable. Examples of such potential applications are too numerous to delineate here; they include the detection of high speed particle impacts on spacecraft structures, dynamic test of radioactive, extremely hot or cold structures, and others. We also note that for the elucidation of the detailed mechanism of fracture, radio-wave emission may have advantages over other methods since, unlike acoustic or ultrasonic methods, the speed of propagation of the detected signal is much greater than the speed of the propagating crack-front in the material, so little or no deconvolution is required.</p

Study of Generation Mechanisms for Laser Ultrasonics

The aerospace industry is beginning to use advanced composite materials for primary load bearing structures and their failure mechanisms must be better understood to predict their behavior in service. The Combined Loads Tests (COLTS) facility is being constructed at the NASA Langley Research Center to characterize these failure mechanisms. Laser based ultrasonic NDE can monitor the samples during dynamic loading without interfering with the structural tests. However, the constraints of implementing laser ultrasound in a structures laboratory reduces the efficiency of the technique. The system has to be “eye-safe” because many people will be present during the structural tests. Consequently, laser light has to be delivered through fiber optics and a significant amount of light is lost. Also, the nature of the composite materials makes laser ultrasonic inspection difficult. The composites of interest are formed from woven layers that are stitched through the laminate thickness and bound in a resin matrix. These materials attenuate ultrasound strongly and exhibit a high degree of scattering. In this paper, we describe a field-deployable laser based ultrasonic NDE system that we developed to investigate structures during testing in the COLTS facility. We illustrate the design constraints that reduced efficiency and present some ultrasonic data from thick stitched composites