air permeability of naturally ventilated italian classrooms

Abstract The study is focused on the evaluation of air permeability and ventilation rate in Italian classrooms. Measurements were performed in 16 naturally ventilated classrooms located in Cassino, Central Italy. Classrooms' airtightness was evaluated through the fan pressurization method. Air exchange rates where both estimated from the blower door results and measured using a CO2 decay test method. The effect of the periodic manual airing of the classrooms (through window and door opening) was also investigated performing CO2 and particle number concentration measurements during the school time

Ventilation strategies to minimise the airborne virus transmission in indoor environments

A key challenge to fight the Covid-19 pandemic is to minimise the airborne transmission of the SARS-CoV-2 virus. Highly crowded indoor environments, such as schools, become possible hotspots for virus spreading because the basic non-pharmaceutical mitigation measures applied until now are not effective in reducing the virus airborne transmission mode, which is the principal one in indoor environments and requires improved ventilation. In the present study, a mass balance equation was applied to typical school scenarios to evaluate (i) required air exchange rates for mechanically-ventilated classrooms and (ii) adequate airing procedures for naturally ventilated classrooms. In the case of naturally ventilated classrooms, a feedback control strategy was evaluated using the measurements of indoor CO2. Our results show how these procedures can be applied in real life to support continued in-person instruction during a pandemic.publishedVersio

Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: A retrospective cohort study in Italy's Marche region

IntroductionWhile increasing the ventilation rate is an important measure to remove inhalable virus-laden respiratory particles and lower the risk of infection, direct validation in schools with population-based studies is far from definitive.MethodsWe investigated the strength of association between ventilation and SARS-CoV-2 transmission reported among the students of Italy's Marche region in more than 10,000 classrooms, of which 316 were equipped with mechanical ventilation. We used ordinary and logistic regression models to explore the relative risk associated with the exposure of students in classrooms.Results and discussionFor classrooms equipped with mechanical ventilation systems, the relative risk of infection of students decreased at least by 74% compared with a classroom with only natural ventilation, reaching values of at least 80% for ventilation rates >10 L s−1 student−1. From the regression analysis we obtained a relative risk reduction in the range 12%15% for each additional unit of ventilation rate per person. The results also allowed to validate a recently developed predictive theoretical approach able to estimate the SARS-CoV-2 risk of infection of susceptible individuals via the airborne transmission route. We need mechanical ventilation systems to protect students in classrooms from airborne transmission; the protection is greater if ventilation rates higher than the rate needed to ensure indoor air quality (>10 L s−1 student−1) are adopted. The excellent agreement between the results from the retrospective cohort study and the outcome of the predictive theoretical approach makes it possible to assess the risk of airborne transmission for any indoor environment

Experimental evaluation of the in-the-field capabilities of total-reflection X-ray fluorescence analysis to trace fine and ultrafine aerosol particles in populated areas

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A 28-nm CMOS pixel read-out ASIC for real-time tracking with time resolution below 20 ps

We present the development of a test ASIC, named Timespot1, designed in CMOS 28-nm technology, featuring a 32x32 pixel matrix and a pitch of 55 μm, The ASIC is conceived as the first prototype in a series, capable to read-out pixels with timing capabilities in the range of 30 ps and below. Each pixel is endowed with a charge amplifier, a discriminator and a Time-to-Digital-Converter, capable of time resolutions below 20 ps and read-out rates (per pixel) around 3 MHz. The timing performance are obtained respecting a power budget of about 50 μW per pixel, corresponding to a power density of approximately 2 W/cm 2 · This feature makes the Timespot1 approach an interesting solution for vertex detectors of the next generation of colliders, where high space and time resolutions will be mandatory requirements to cope with the huge amount of tracks per event to be detected and processed

An Exploratory Study of Nonsuicidal Self-Injury and Suicidal Behaviors in Adolescent Latinas

To date, there is little research to validate empirically differences between nonsuicidal self-injurious behavior (NSSI) and attempted suicide among Latina adolescents. Understanding the characteristics and contextual features of self-harmful behaviors among Latina teens is a critical public health and social justice matter given the disproportionate rates of attempted suicide and anticipated population growth of this vulnerable group. In this article, we draw on an ecodevelopmental model to focus attention on factors in the sociocultural environment that shape suicidal behaviors and NSSIs. Through analysis of qualitative interviews conducted with girls who used NSSI (n ! 18), attempted suicide (n ! 29), used NSSI and attempted suicide (n ! 8,) and had no reported lifetime history of self-harm (n ! 28), we describe the sociocultural factors that shaped psychosocial vulnerabilities and gave rise to decisions to use NSSI or attempt suicide. Our analysis revealed that adolescents who engaged in NSSI perceived their negative feelings as something that could be controlled through self-injurious acts, whereas powerlessness was a theme underlying the emotional states of girls who attempted suicide. When NSSI ceased to function as a mechanism for control, girls came to sudden decisions to attempt suicide. Most teens identified specific, and often multiple, situations that induced intense affective states and shaped decisions to inflict self-harm. Two situational experiences emerged as particularly salient and promising for subsequent studies on self-harmful behaviors among Latina adolescents: transnational stress and bullying. We describe each of these and offer suggestions for future research and practice

Timespot1: A 28nm CMOS Pixel Read-Out ASIC for 4D Tracking at High Rates

We present the first characterization results of Timespot1, an ASIC designed in CMOS 28 nm technology, featuring a $32 \times 32$ pixel matrix with a pitch of $55 ~ \mu m$. Timespot1 is the first small-size prototype, conceived to readout fine-pitch pixels with single-hit time resolution below $50 ~ ps_\text{rms}$ and input rates of several hundreds of kilohertz per pixel. Such experimental conditions will be typical of the next generation of high-luminosity collider experiments, from the LHC run5 and beyond. Each pixel of the ASIC includes a charge amplifier, a discriminator, and a Time-to-Digital Converter with time resolution indicatively of $22.6 ~ ps_\text{rms}$ and maximum readout rates (per pixel) of $3 ~ MHz$. To respect system-level constraints, the timing performance has been obtained keeping the power budget per pixel below $40 ~ \mu W$. The ASIC has been tested and characterised in the laboratory concerning its performance in terms of time resolution, power budget and sustainable rates. The ASIC will be hybridized on a matched $32 \times 32$ pixel sensor matrix and will be tested under laser beam and Minimum Ionizing Particles in the laboratory and at test beams. In this paper we present a description of the ASIC operation and the first results obtained from characterization tests concerning its performance

An Exploratory Study of Nonsuicidal Self-Injury and Suicidal Behaviors in Adolescent Latinas

To date, there is little research to validate empirically differences between nonsuicidal self-injurious behavior (NSSI) and attempted suicide among Latina adolescents. Understanding the characteristics and contextual features of self-harmful behaviors among Latina teens is a critical public health and social justice matter given the disproportionate rates of attempted suicide and anticipated population growth of this vulnerable group. In this article, we draw on an ecodevelopmental model to focus attention on factors in the sociocultural environment that shape suicidal behaviors and NSSIs. Through analysis of qualitative interviews conducted with girls who used NSSI (n ! 18), attempted suicide (n ! 29), used NSSI and attempted suicide (n ! 8,) and had no reported lifetime history of self-harm (n ! 28), we describe the sociocultural factors that shaped psychosocial vulnerabilities and gave rise to decisions to use NSSI or attempt suicide. Our analysis revealed that adolescents who engaged in NSSI perceived their negative feelings as something that could be controlled through self-injurious acts, whereas powerlessness was a theme underlying the emotional states of girls who attempted suicide. When NSSI ceased to function as a mechanism for control, girls came to sudden decisions to attempt suicide. Most teens identified specific, and often multiple, situations that induced intense affective states and shaped decisions to inflict self-harm. Two situational experiences emerged as particularly salient and promising for subsequent studies on self-harmful behaviors among Latina adolescents: transnational stress and bullying. We describe each of these and offer suggestions for future research and practice