Endogenous magnetic resonance contrast based on the localized composition of fat in vivo can provide functional information. We found that the unequal pulse timings of the Uhrig’s Dynamical Decoupling (UDD) multipulse echo sequences significantly alter the signal intensity compared to conventional, equal-spaced Carr-Purcell-Meiboom-Gill (CPMG) sequences. The signal increases and decreases depending on the tissue and sequence parameters, as well as on the interpulse spacings; particularly strong differences were observed in fatty tissues, which have a highly structured morphology and a wide range of chemical shifts and J-couplings. We found that the predominant mechanism for fat refocusing under multipulse echo sequences is the chemical structure, with stimulated echoes playing a pivotal role. As a result, specialized pulse sequences can be designed to optimize refocusing of the fat chemical shifts and J-couplings, where the degree of refocusing can be tailored to specific types of fats. To determine the optimal time delays, we simulated various UDD and CPMG pulse sequence timings, and these results are compared to experimental results obtained on excised and in vivo fatty tissue. Applications to intermolecular multiple-quantum coherence (iMQC) imaging, where the improved echo refocusing translates directly into signal enhancements, are presented as well.

Abstract. We demonstrate a multimodal approach that combines a pump-probe with confocal reflectance and multiphoton autofluorescence microscopy. Pump-probe microscopy has been proven to be of great value in analyzing thin tissue sections of pigmented lesions, as it produces molecular contrast which is inaccessible by other means. However, the higher optical intensity required to overcome scattering in thick tissue leads to higher-order nonlinearities in the optical response of melanin (e.g., two-photon pump and one-photon probe) that present additional challenges for interpreting the data. We show that analysis of pigment composition in vivo must carefully account for signal terms that are nonlinear with respect to the pump and probe intensities. We find that pump-probe imaging gives useful contrast for pigmented structures over a large range of spatial scales (100 μm to 1 cm), making it a potentially useful tool for tracking the progression of pigmented lesions without the need to introduce exogenous contrast agents.

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Working parents of children with special needs (i.e., emotional, behavioral, and/or learning difficulties) face recurrent stressors that can make balancing work and family demands difficult. This strain has been magnified during the COVID-19 pandemic, as these parents often need to take on greater responsibility in supporting their children's remote learning, while still meeting their own job-related responsibilities. Accordingly, working parents of special needs children may be particularly vulnerable to adverse outcomes stemming from pandemic-induced changes to work (e.g., teleworking) and education (e.g., remote instruction). We sought to understand how daily family and work challenges influence satisfaction with work-life balance (WLB) in this priority population, with an emphasis on contextualizing this process through chronic job stress perceptions. Conducting a 10-day daily diary study in a sample of 47 working parents of special needs children during fall 2020, we observed family challenges to deplete positive affect from day-to-day, which undermined satisfaction with work-life balance. Furthermore, detrimental influences of daily family and work challenges on positive affect were magnified under chronic job stress, yielding diminished WLB satisfaction for more chronically stressed employees. We discuss how these findings can be harnessed to support particularly vulnerable employees during the COVID-19 pandemic and other chronic stress circumstances, while also drawing attention to how the pandemic may be exacerbating work-life inequities that some employees face.

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