1,142 research outputs found
Specific Drosophila Dscam juxtamembrane variants control dendritic elaboration and axonal arborization
Drosophila Dscam isoforms are derived from two alternative transmembrane/juxtamembrane domains (TMs) in addition to thousands of ectodomain variants. Using a microRNA-based RNA interference technology, we selectively knocked down different subsets of Dscams containing either the exon 17.1- or exon 17.2-encoding TM. Eliminating Dscam[TM1] reduced Dscam expression but minimally affected postembryonic axonal morphogenesis. In contrast, depleting Dscam[TM2] blocked axon arborization. Further removal of Dscam[TM1] enhanced the loss-of-Dscam[TM2] axonal phenotypes. However, Dscam[TM1] primarily regulates dendritic development, as evidenced by the observations that removing Dscam[TM1] alone impeded elaboration of dendrites and that transgenic Dscam[TM1], but not Dscam[TM2], effectively rescued Dscam mutant dendritic phenotypes in mosaic organisms. These distinct Dscam functions can be attributed to the juxtamembrane regions of TMs that govern dendritic versus axonal targeting of Dscam as well. Together, we suggest that specific Drosophila Dscam juxtamembrane variants control dendritic elaboration and axonal arborization
Nonlinear photoacoustic microscopy via a loss modulation technique: from detection to imaging
In order to achieve high-resolution deep-tissue imaging, multi-photon fluorescence microscopy and photoacoustic tomography had been proposed in the past two decades. However, combining the advantages of these two imaging systems to achieve optical-spatial resolution with an ultrasonic-penetration depth is still a field with challenges. In this paper, we investigate the detection of the two-photon photoacoustic ultrasound, and first demonstrate background-free two-photon photoacoustic imaging in a phantom sample. To generate the background-free two-photon photoacoustic signals, we used a high-repetition rate femtosecond laser to induce narrowband excitation. Combining a loss modulation technique, we successfully created a beating on the light intensity, which not only provides pure sinusoidal modulation, but also ensures the spectrum sensitivity and frequency selectivity. By using the lock-in detection, the power dependency experiment validates our methodology to frequency-select the source of the nonlinearity. This ensures our capability of measuring the background-free two-photon photoacoustic waves by detecting the 2nd order beating signal directly. Furthermore, by mixing the nanoparticles and fluorescence dyes as contrast agents, the two-photon photoacoustic signal was found to be enhanced and detected. In the end, we demonstrate subsurface two-photon photoacoustic bio-imaging based on the optical scanning mechanism inside phantom samples
MiniSUPERB: Lightweight Benchmark for Self-supervised Speech Models
Self-supervised learning (SSL) is a popular research topic in speech
processing. Successful SSL speech models must generalize well. SUPERB was
proposed to evaluate the ability of SSL speech models across many speech tasks.
However, due to the diversity of tasks, the evaluation process requires huge
computational costs. We present MiniSUPERB, a lightweight benchmark that
efficiently evaluates SSL speech models with comparable results to SUPERB while
greatly reducing the computational cost. We select representative tasks and
sample datasets and extract model representation offline, achieving 0.954 and
0.982 Spearman's rank correlation with SUPERB Paper and SUPERB Challenge,
respectively. In the meanwhile, the computational cost is reduced by 97% in
regard to MACs (number of Multiply-ACcumulate operations) in the tasks we
choose. To the best of our knowledge, this is the first study to examine not
only the computational cost of a model itself but the cost of evaluating it on
a benchmark
Time-Selective RNN for Device-Free Multi-Room Human Presence Detection Using WiFi CSI
Human presence detection is a crucial technology for various applications,
including home automation, security, and healthcare. While camera-based systems
have traditionally been used for this purpose, they raise privacy concerns. To
address this issue, recent research has explored the use of channel state
information (CSI) approaches that can be extracted from commercial WiFi access
points (APs) and provide detailed channel characteristics. In this thesis, we
propose a device-free human presence detection system for multi-room scenarios
using a time-selective conditional dual feature extract recurrent Network
(TCD-FERN). Our system is designed to capture significant time features with
the condition on current human features using a dynamic and static (DaS) data
preprocessing technique to extract moving and spatial features of people and
differentiate between line-of-sight (LoS) path blocking and non-blocking cases.
To mitigate the feature attenuation problem caused by room partitions, we
employ a voting scheme. We conduct evaluation and real-time experiments to
demonstrate that our proposed TCD-FERN system can achieve human presence
detection for multi-room scenarios using fewer commodity WiFi APs
Endodomain diversity in the Drosophila Dscam and its roles in neuronal morphogenesis
Drosophila Down syndrome cell adhesion molecule (Dscam) can be variably spliced to encode 152,064 distinct single-pass transmembrane proteins. In addition to 19,008 possible ectodomains and two alternative transmembrane segments, it may carry endodomains containing or lacking exons 19 and 23. Here, we determine the role of Dscam endodomain diversity in neural development. Dscam with full-length endodomain is largely restricted to embryogenesis. In contrast, most Dscams lack exons 19 and 23 at postembryonic stages. As implicated from the expression patterns, removal of Dscam exon 19-containing variants disrupts wiring of embryonic neurons while silencing of Dscam transcripts lacking exon 19 or exon 23 effectively blocks postembryonic neuronal morphogenesis. Furthermore, compared with exon 19-containing Dscam, transgenic Dscam without exon 19 is more efficiently targeted to neurites and more potently suppresses axon bifurcation in Dscam mutant neurons. In sum, Dscam with or without exon 19 in its endodomain is used to govern different stage-specific neuronal morphogenetic processes, possibly due to differences in protein targeting
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