Navegando por Palavras-chave "Attenuation"

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    Atenuação viral em solos tropicais
    (Universidade Federal de São Paulo, 2016-04-04) Galvez, Margarita Nuche [UNIFESP]; Freitas, Juliana Gardenalli de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Groundwater contamination by viruses is an important threat to public health, however this type of contaminant can be significantly attenuated by viral adsorption and inactivation. Since groundwater is needed for water supply, understanding and quantifying these processes is important to define strategies to minimize risks to human health. The occurrence of these processes depends on several factors and few studies have evaluated the behavior of viruses in tropical soils. In this context, this work aims to assess the transport and behavior of viruses in two soils of high occurrence in Brazil: a Typic Hapludox and an Udoxic Quartzipsamment. The ?X174 bacteriophage was selected for quantifying viral attenuation, because it is an useful substitute for human enteric viruses. Laboratory experiments were conducted injecting a pulse of bacteriophages suspended in water into soil columns. The obtained results were compared with a non-reactive tracer (bromide) and an inert material (glass beads). The Typic Hapludox showed higher viral attenuation capacity (>99,997%) than the Udoxic Quartzipsamment (>99,982%). The dominant processes were adsorption in the Typic Hapludox (up to 80.98%) and inactivation in the Udoxic Quartzipsamment (up to 83.17%). The bacteriophage was transported at a higher velocity than bromide tracer, due to exclusion processes. Mean pH values (?5) promoved electrostatic adsorption of phage to soil, but reduction in acidity increased phage release and transport was facilitated in some tests by co-transport mechanisms. Therefore, the presence of Typic Hapludox and Udoxic Quartzipsamment can result in significant protection of groundwater quality for viral contamination. However, more laboratory research is needed to examine the impact of other environmental factors and also field tests to help determine wellhead protection zones, to ensure safety of supply.
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    The Study of Attenuation Levels and the Comfort of Earplugs
    (Medknow Publications & Media Pvt Ltd, 2018) Samelli, Alessandra G.; Gomes, Raquel F.; Chammas, Tiago V.; Silva, Barbara G.; Moreira, Renata R.; Fiorini, Ana Claudia [UNIFESP]
    Introduction: This study aimed to analyze and compare four different types of earplugs, divided into premolded plugs and foam plug models, in relation to the level of attenuation, comfort, and the size of the external acoustic meatus (EAM) in an attempt to identify how these variables influence the choice of specific hearing protection devices (HPDs). Materials and Methods: A cross-sectional observational study was performed in a sample of 49 participants, oriented toward the ideal placement of four HPDs, two premolded and two foam plugs (3M (TM)). The procedures included otoscopy, EAM diameter measurement using an otometer, EAM volume measurement via an acoustic impedance test, and the obtainment of the bilateral personal attenuation rating (PAR) for each HPD using the E-A-Rfit (TM) Validation System (3M (TM)). The Bipolar Comfort Rating Scale (BCRS) instrument was applied twice for each individual: once after the evaluations with the premolded HPDs and again after the evaluations with the foam plug HPDs. Then, each participant was asked which was his/her favorite protector. Results: The volume of the EAM was not directly related to the diameter of the EAM. The attenuation did not interfere with the HPD preference, and the PAR of the foam plug was significantly higher regardless of the preferred HPD. Regarding the BCRS, the variables "Placement," "Complexity," and "Occlusion Effect" had higher scores for premolded HPDs and had a direct relationship with the type of preferred HPD. Conclusion: Attention to the use of HPDs should be personalized, taking into account the needs of each individual, considering not only the attenuation, but also the user's reported well-being.