3D-printed micro lens-in-lens for in vivo multimodal microendoscopy

Published online: March 1, 2022Multimodal microendoscopes enable co-located structural and molecular measurements in vivo, thus providing useful insights into the pathological changes associated with disease. However, different optical imaging modalities often have conflicting optical requirements for optimal lens design. For example, a high numerical aperture (NA) lens is needed to realize high-sensitivity fluorescence measurements. In contrast, optical coherence tomography (OCT) demands a low NA to achieve a large depth of focus. These competing requirements present a significant challenge in the design and fabrication of miniaturized imaging probes that are capable of supporting high-quality multiple modalities simultaneously. An optical design is demonstrated which uses two-photon 3D printing to create a miniaturized lens that is simultaneously optimized for these conflicting imaging modalities. The lens-in-lens design contains distinct but connected optical surfaces that separately address the needs of both fluorescence and OCT imaging within a lens of 330 µm diameter. This design shows an improvement in fluorescence sensitivity of >10x in contrast to more conventional fiber-optic design approaches. This lens-in-lens is then integrated into an intravascular catheter probe with a diameter of 520 µm. The first simultaneous intravascular OCT and fluorescence imaging of a mouse artery in vivo is reported.Jiawen Li, Simon Thiele, Rodney W. Kirk, Bryden C. Quirk, Ayla Hoogendoorn, Yung Chih Chen, Karlheinz Peter, Stephen J. Nicholls, Johan W. Verjans, Peter J. Psaltis, Christina Bursill, Alois M. Herkommer, Harald Giessen, and Robert A. McLaughli

A multi-species synthesis of physiological mechanisms in drought-induced tree mortality

Widespread tree mortality associated with drought 92 has been observed on all forested continents, and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water, and energy balance, and is poorly represented in dynamic vegetation models. Reducing uncertainty requires improved mortality projections founded on robust physiological processes. However, the proposed mechanisms of drought-induced mortality, including hydraulic failure and carbon starvation, are unresolved. A growing number of empirical studies have investigated these mechanisms, but data have not been consistently analyzed across species and biomes using a standardized physiological framework. Here we show that xylem hydraulic failure was ubiquitous across multiple tree taxa at drought induced mortality. All species assessed had 60% or higher loss of xylem hydraulic conductivity, consistent with proposed theoretical and modelled survival thresholds. We found diverse responses in non-structural carbohydrate reserves at mortality, indicating that evidence supporting carbon starvation was not universal. Reduced non-structural carbohydrates were more common for gymnosperms than angiosperms, associated with xylem hydraulic vulnerability, and may have a role in reducing hydraulic function. Our finding that hydraulic failure at drought-induced mortality was persistent across species indicates that substantial improvement in vegetation modelling can be achieved using thresholds in hydraulic function

A multi-species synthesis of physiological mechanisms in drought-induced tree mortality

Widespread tree mortality associated with drought 92 has been observed on all forested continents, and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water, and energy balance, and is poorly represented in dynamic vegetation models. Reducing uncertainty requires improved mortality projections founded on robust physiological processes. However, the proposed mechanisms of drought-induced mortality, including hydraulic failure and carbon starvation, are unresolved. A growing number of empirical studies have investigated these mechanisms, but data have not been consistently analyzed across species and biomes using a standardized physiological framework. Here we show that xylem hydraulic failure was ubiquitous across multiple tree taxa at drought induced mortality. All species assessed had 60% or higher loss of xylem hydraulic conductivity, consistent with proposed theoretical and modelled survival thresholds. We found diverse responses in non-structural carbohydrate reserves at mortality, indicating that evidence supporting carbon starvation was not universal. Reduced non-structural carbohydrates were more common for gymnosperms than angiosperms, associated with xylem hydraulic vulnerability, and may have a role in reducing hydraulic function. Our finding that hydraulic failure at drought-induced mortality was persistent across species indicates that substantial improvement in vegetation modelling can be achieved using thresholds in hydraulic function

The Machinery of Democracy: Voting Systems and Ballot Miscounts in Illinois

The outcome of the 2000 presidential election focused unprecedented national attention on apparent inequities in the election process. Before the controversies surrounding that election, few citizens had been aware that a substantial portion of votes for major offices were regularly not counted because either citizens marked ballots incorrectly or voting equipment recorded them incorrectly. After the election, evidence also emerged that some jurisdictions had miscount rates that were dramatically higher than others. What caused the wide variation in miscount rates? Was it racism, as some have suggested? Was it the machinery itself? Or, was it something else? Authors Paul Quirk, James Kuklinski and Philip Habel come to some surprising conclusions

Toward the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy

We describe a study of the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy. Diffuse reflectance spectra in the wavelength range 550 to 1000 nm are obtained using 400-µm core multimode fibers arranged in a six-illumination-around-one- collection geometry with a single fiber-fiber spacing of 470 µm. Spectra are collected at specific locations on 120 pigmented lesions selected by clinicians as possible melanoma, including 64 histopathologically diagnosed as melanoma. These locations are carried through to the histopathological diagnosis, permitting a spatially localized comparison with the corresponding spectrum. The variations in spectra between groups of lesions with different diagnoses are examined and reduced to features suitable for discriminant analysis. A classifier distinguishing between benign and malignant lesions performs with sensitivity/ specificity of between 64/69% and 72/78%. Classifiers between pairs of the group common nevus, dysplastic nevus, in situ melanoma, and invasive melanoma show better or similar performance than the benign/malignant classifier, and analysis provides evidence that different spectral features are needed for each pair of groups. This indicates that multiple discriminant systems are likely to be required to distinguish between melanoma and similar lesions

Toward the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy

We describe a study of the discrimination of early melanoma from common and dysplastic nevus using fiber optic diffuse reflectance spectroscopy. Diffuse reflectance spectra in the wavelength range 550 to 1000 nm are obtained using 400-µm core multimode fibers arranged in a six-illumination-around-one- collection geometry with a single fiber-fiber spacing of 470 µm. Spectra are collected at specific locations on 120 pigmented lesions selected by clinicians as possible melanoma, including 64 histopathologically diagnosed as melanoma. These locations are carried through to the histopathological diagnosis, permitting a spatially localized comparison with the corresponding spectrum. The variations in spectra between groups of lesions with different diagnoses are examined and reduced to features suitable for discriminant analysis. A classifier distinguishing between benign and malignant lesions performs with sensitivity/ specificity of between 64/69% and 72/78%. Classifiers between pairs of the group common nevus, dysplastic nevus, in situ melanoma, and invasive melanoma show better or similar performance than the benign/malignant classifier, and analysis provides evidence that different spectral features are needed for each pair of groups. This indicates that multiple discriminant systems are likely to be required to distinguish between melanoma and similar lesions

Women with bulimic eating disorders: when do they receive treatment for an eating problem?

Variables associated with the use of health services were examined in a prospective, community-based study of women with bulimic-type eating disorders who did (n = 33) or did not (n = 58) receive treatment for an eating problem during a 12-month follow-up period. Participants who received treatment for an eating problem differed from those who did not in several respects, including higher body weight, higher levels of eating disorder psychopathology, general psychological distress, and impairment in role functioning, deficits in specific aspects of coping style, greater awareness of an eating problem, and greater likelihood of prior treatment for a problem with weight. However, the variables most strongly associated with treatment seeking were greater perceived impairment in role functioning specifically associated with an eating problem and greater perceived inability to suppress emotional difficulties. These were the only variables that were significantly associated with treatment seeking in multivariable analysis. The findings suggest that individuals’ recognition of the adverse effects of eating-disordered behavior on quality of life may need to be addressed in prevention and early intervention programs for eating disorders

Preparation of poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and polyamide-6 blends via activated anionic polymerization of PPE and ε-caprolactam solutions

Activated anionic polymn. of homogeneous PPE/e-caprolactam solns. below the m.p. of polyamide-6 (PA-6) in the presence of a catalyst results in the prepn. of PPE/PA-6 blends. The morphol. of these blends consists of a continuous PPE and dispersed PA-6 phase or vice versa, depending on the PPE concn. The particle size of the dispersed PA-6 phase in the continuous PPE matrix is detd. by the viscosit