Quanta Burst Photography

Single-photon avalanche diodes (SPADs) are an emerging sensor technology capable of detecting individual incident photons, and capturing their time-of-arrival with high timing precision. While these sensors were limited to single-pixel or low-resolution devices in the past, recently, large (up to 1 MPixel) SPAD arrays have been developed. These single-photon cameras (SPCs) are capable of capturing high-speed sequences of binary single-photon images with no read noise. We present quanta burst photography, a computational photography technique that leverages SPCs as passive imaging devices for photography in challenging conditions, including ultra low-light and fast motion. Inspired by recent success of conventional burst photography, we design algorithms that align and merge binary sequences captured by SPCs into intensity images with minimal motion blur and artifacts, high signal-to-noise ratio (SNR), and high dynamic range. We theoretically analyze the SNR and dynamic range of quanta burst photography, and identify the imaging regimes where it provides significant benefits. We demonstrate, via a recently developed SPAD array, that the proposed method is able to generate high-quality images for scenes with challenging lighting, complex geometries, high dynamic range and moving objects. With the ongoing development of SPAD arrays, we envision quanta burst photography finding applications in both consumer and scientific photography.Comment: A version with better-quality images can be found on the project webpage: http://wisionlab.cs.wisc.edu/project/quanta-burst-photography

Sensor Network Architecture for a Fully Digital and Scalable SPAD based PET System

Digital SiPMs in the recent past have emerged as a viable low cost alternative to PMTs providing higher granularity and MRI compatibility. The rich dataset generated by digital SiPM sensors have posed a challenge, especially at the system level when a multitude of such sensors are to be used. In this paper we present a sensor network based solution for data acquisition, scalable to multi-ring based pre-clinical, clinical and brain PET

Testing for the myth of cognitive reserve. Are the static and dynamic cognitive reserve indexes a representation of different reserve warehouses?

Background: Cognitive reserve (CR) explains the individual resilience to neurodegeneration. Years of formal education express the static measure of reserve (sCR). A dynamic aspect of CR (dCR) has been recently proposed. Objective: The aim of the study was to compare sCR and dCR indexes, respectively, to detect brain abnormalities in Alzheimer's disease (AD) patients. Methods: 117 individuals [39 AD, 40 amnestic mild cognitive impairment (aMCI), 38 healthy subjects (HS)] underwent neuropsychological evaluation and a 3T-MRI. T1-weighted volumes were used for manual segmentation of the hippocampus and of the parahippocampal cortices. Years of formal education were used as an index of sCR. Partial Least Square analysis was used to decompose the variance of individual MMSE scores, considered as a dCR index. In aMCI and AD patients, the brain abnormalities have been assessed comparing individuals with high and low levels of sCR and dCR in turn. Moreover, we investigated the effect of the different CR indexes in mediating the relationship between changes in brain volumes and memory performances. Results: sCR and dCR indexes classified differently individuals having high or low levels of CR. Smaller hippocampal and parahippocampal volumes in high dCR patients were found. The sCR and dCR indexes mediated significantly the relationship between brain abnormalities and memory in patients. Conclusions: CR mediated the relationship between brain and memory dysfunctions. We hypothesized that sCR and dCR indexes are a representation of different warehouses of reserve not operating in parallel but forming a complex system, in which crystalized cognitive abilities and actual cognitive efficiency interact with brain atrophy impacting on memory

The decline of the charismatic Parnassius mnemosyne (L.) (Lepidoptera: Papilionidae) in a Central Italy national park: a call for urgent actions

Here we report the strong decline of a population of the endangered species Parnassius mnemosyne (Linnaeus, 1758) (Lepidoptera: Papilionidae) in the National Park of Foreste Casentinesi, Monte Falterona and Campigna (Italy). We compared historical presence data (before 1969) with current data from two years of monitoring (2018–2019) and provided evidence of a drastic reduction in the number of sites inhabited by the species. A preliminary assessment suggested that the population of P. mmemosyne occurring in the Park is limited to a few individuals. We argue that the population of this iconic and charismatic butterfly is at the verge of extinction in this National Park, probably because of a combination of habitat loss (i.e. decrease in size and number of areas of open grassland on the mountain belt) and climatic changes. Being one of the few populations of P. mnemosyne in the Northern Apennines, the implementation of protection measures is a high conservation priority. Several other butterfly species on the Italian mountains that are facing the same survival challenges would also benefit from the establishment of conservation actions aimed at improving habitat quality for P. mnemosyne. Present article is meant to call for action researchers, stakeholders, and especially decision-makers in order to increase the efforts to upturn the evident decline in abundance of this population