Two statistical regimes in the transition to filamentation.

We experimentally investigate fluctuations in the spectrum of ultrashort laser pulses propagating in air, close to the critical power for filamentation. Increasing the laser peak power broadens the spectrum while the beam approaches the filamentation regime. We identify two regimes for this transition: In the center of the spectrum, the output spectral intensity increases continuously.

Assessing classroom and laboratory spread of COVID-19 in a university after elimination of physical distancing.

The objective of this study was to assess COVID-19 classroom transmission in the university setting when physical distancing was eliminated. Data was collected in fall 2021 at a private university. Universal masking, robust contact tracing, vaccination requirement, and enforced testing were in place.

Impacts of the COVID-19 pandemic on the infection prevention and control field: Findings from focus groups conducted with association for professionals in infection control & epidemiology (APIC) members in fall 2021.

Introduction: Emergence of the Delta variant in 2021 changed the pandemic landscape and led to healthcare surges across the US, despite availability of COVID-19 vaccine. Anecdotal information indicated that the infection prevention and control (IPC) field was changing, but formal assessment was needed.

Methods: Focus groups (6) were conducted with APIC members in November and December, 2021 to elicit infection preventionists' (IP) opinions changes to the IPC field due to the pandemic.

Infection preventionists' experiences during the second year of the COVID-19 pandemic: Findings from focus groups conducted with association for professionals in infection control & epidemiology (APIC) members.

Introduction: COVID-19 epidemiology changed dramatically in spring 2021 when vaccine became widely available and the Delta variant emerged. There was a need to identify current infection prevention challenges due to changing pandemic epidemiology.

Methods: Six focus groups were conducted via Zoom with APIC members in November and December, 2021 to elicit infection preventionists' (IP) experiences with the COVID-19 pandemic after the Delta variant had emerged.

Modifications to student quarantine policies in K-12 schools implementing multiple COVID-19 prevention strategies restores in-person education without increasing SARS-CoV-2 transmission risk, January-March 2021.

Objective: To determine whether modified K-12 student quarantine policies that allow some students to continue in-person education during their quarantine period increase schoolwide SARS-CoV-2 transmission risk following the increase in cases in winter 2020-2021.

Methods: We conducted a prospective cohort study of COVID-19 cases and close contacts among students and staff (n = 65,621) in 103 Missouri public schools. Participants were offered free, saliva-based RT-PCR testing.