117 research outputs found
Evaluation of the Relationship Between Cognitive Impairment, Glycometabolism, and Nicotinic Acetylcholine Receptor Deficits in a Mouse Model of Alzheimer's Disease
PURPOSE:
In patients with Alzheimer's disease (AD), the loss of cerebral nicotinic acetylcholine receptors (nAChRs) that are implicated in higher brain functions has been reported. However, it is unclear if nAChR deficits occur in association with cognitive impairments. The purpose of this study was to assess the relationship between nAChR deficits and cognitive impairments in a mouse model of AD (APP/PS2 mice).
PROCEDURES:
The cognitive abilities of APP/PS2 and wild-type mice (aged 2-16 months) were evaluated using the novel object recognition test. Double-tracer autoradiography analyses with 5-[125I]iodo-A-85380 ([125I]5IA: α4β2 nAChR imaging probe) and 2-deoxy-2-[18F]fluoro-D-glucose were performed in both mice of different ages. [123I]5IA-single-photon emission tomography (SPECT) imaging was also performed in both mice at 12 months of age. Furthermore, each age cohort was investigated for changes in cognitive ability and expression levels of α7 nAChRs and N-methyl-D-aspartate receptors (NMDARs).
RESULTS:
No significant difference was found between the APP/PS2 and wild-type mice at 2-6 months of age in terms of novel object recognition memory; subsequently, however, APP/PS2 mice showed a clear cognitive deficit at 12 months of age. [125I]5IA accumulation decreased in the brains of 12-month-old APP/PS2 mice, i.e., at the age at which cognitive impairments were first observed; this result was supported by a reduction in the protein levels of α4 nAChRs using Western blotting. nAChR deficits could be noninvasively detected by [123I]5IA-SPECT in vivo. In contrast, no significant changes in glycometabolism, expression levels of α7 nAChRs, or NMDARs were associated with cognitive impairments in APP/PS2 mice.
CONCLUSION:
A decrease in cerebral α4β2 nAChR density could act as a biomarker reflecting cognitive impairments associated with AD pathology
All-microwave manipulation of superconducting qubits with a fixed-frequency transmon coupler
All-microwave control of fixed-frequency superconducting quantum computing
circuits is advantageous for minimizing the noise channels and wiring costs.
Here we introduce a swap interaction between two data transmons assisted by the
third-order nonlinearity of a coupler transmon under a microwave drive. We
model the interaction analytically and numerically and use it to implement an
all-microwave controlled-Z gate. The gate based on the coupler-assisted swap
transition maintains high drive efficiency and small residual interaction over
a wide range of detuning between the data transmons.Comment: 12 pages, 8 figure
What Do Self-Supervised Speech and Speaker Models Learn? New Findings From a Cross Model Layer-Wise Analysis
Self-supervised learning (SSL) has attracted increased attention for learning
meaningful speech representations. Speech SSL models, such as WavLM, employ
masked prediction training to encode general-purpose representations. In
contrast, speaker SSL models, exemplified by DINO-based models, adopt
utterance-level training objectives primarily for speaker representation.
Understanding how these models represent information is essential for refining
model efficiency and effectiveness. Unlike the various analyses of speech SSL,
there has been limited investigation into what information speaker SSL captures
and how its representation differs from speech SSL or other fully-supervised
speaker models. This paper addresses these fundamental questions. We explore
the capacity to capture various speech properties by applying SUPERB evaluation
probing tasks to speech and speaker SSL models. We also examine which layers
are predominantly utilized for each task to identify differences in how speech
is represented. Furthermore, we conduct direct comparisons to measure the
similarities between layers within and across models. Our analysis unveils that
1) the capacity to represent content information is somewhat unrelated to
enhanced speaker representation, 2) specific layers of speech SSL models would
be partly specialized in capturing linguistic information, and 3) speaker SSL
models tend to disregard linguistic information but exhibit more sophisticated
speaker representation.Comment: Accepted at ICASSP 202
RNA-seq-based evaluation of bicolor tepal pigmentation in Asiatic hybrid lilies (Lilium spp.)
Background: Color patterns in angiosperm flowers are produced by spatially and temporally restricted deposition of pigments. Identifying the mechanisms responsible for restricted pigment deposition is a topic of broad interest. Some dicots species develop bicolor petals, which are often caused by the post-transcriptional gene silencing (PTGS) of chalcone synthase (CHS) genes. An Asiatic hybrid lily (Lilium spp.) cultivar Lollypop develops bicolor tepals with pigmented tips and white bases. Here, we analyzed the global transcription of pigmented and non-pigmented tepal parts from Lollypop, to determine the main transcriptomic differences. Results: De novo assembly of RNA-seq data yielded 49,239 contigs (39,426 unigenes), which included a variety of novel transcripts, such as those involved in flavonoid-glycosylation and sequestration and in regulation of anthocyanin biosynthesis. Additionally, 1258 of the unigenes exhibited significantly differential expression between the tepal parts (false discovery rates 2-fold higher in the pigmented parts. Thus, LhMYB12 should be involved in the transcriptional regulation of the biosynthesis genes in bicolor tepals. Other factors that potentially suppress or enhance the expression of anthocyanin biosynthesis genes, including a WD40 gene, were identified, and their involvement in bicolor development is discussed. Conclusions: Our results indicate that the bicolor trait of Lollypop tepals is caused by the transcriptional regulation of anthocyanin biosynthesis genes and that the transcription profile of LhMYB12 provides a clue for elucidating the mechanisms of the trait. The tepal transcriptome constructed in this study will accelerate investigations of the genetic controls of anthocyanin color patterns, including the bicolor patterns, of Lilium spp
Photon-noise-tolerant dispersive readout of a superconducting qubit using a nonlinear Purcell filter
Residual noise photons in a readout resonator become a major source of
dephasing for a superconducting qubit when the resonator is optimized for a
fast, high-fidelity dispersive readout. Here, we propose and demonstrate a
nonlinear Purcell filter that suppresses such an undesired dephasing process
without sacrificing the readout performance. When a readout pulse is applied,
the filter automatically reduces the effective linewidth of the readout
resonator, increasing the sensitivity of the qubit to the input field. The
noise tolerance of the device we fabricated is shown to be enhanced by a factor
of three relative to a device with a linear filter. The measurement rate is
enhanced by another factor of three by utilizing the bifurcation of the
nonlinear filter. A readout fidelity of 99.4% and a QND fidelity of 99.2% are
achieved using a 40-ns readout pulse. The nonlinear Purcell filter will be an
effective tool for realizing a fast, high-fidelity readout without compromising
the coherence time of the qubit.Comment: 13 pages, 9 figure
Spin fluctuations from Bogoliubov Fermi surfaces in the superconducting state of S-substituted FeSe
The study of the iron-based superconductor, FeSe, has resulted in various
topics, such as the interplay among superconductivity, nematicity, and
magnetism, Bardeen-Cooper-Schrieffer Bose-Einstein-condensation (BCS-BEC)
crossover, and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity.
Recently, topologically protected nodal Fermi surfaces, referred to as
Bogoliubov Fermi surfaces (BFSs), have garnered much attention. A theoretical
model for the S-substituted FeSe system demonstrated that BFSs can manifest
under the conditions of spin-orbit coupling, multi-band systems, and
superconductivity with time-reversal symmetry breaking. Here we report the
observation of spin fluctuations originating from BFSs in the superconducting
(SC) state via Se-nuclear magnetic resonance measurements to 100 mK. In
a heavily S-substituted FeSe, we found an anomalous enhancement of low-energy
spin fluctuations deep in the SC state, which cannot be explained by an
impurity effect. Such unusual behavior implies the presence of significant spin
fluctuations of Bogoliubov quasiparticles, which are associated with possible
nesting properties between BFSs
PHOSPHATEMIC INDEX EVALUATES PHOSPHORUS LOAD
Objective: Dietary phosphorus (P) restriction is crucial to treat hyperphosphatemia and reduce cardiovascular disease risk and mortality in patients with chronic kidney disease (CKD) and the wider population. Various methods for dietary P restriction exist, but the bioavailability of P in food should also be considered when making appropriate food choices to maintain patients’ quality of life. Here, we propose the ‘‘Phosphatemic Index’’ (PI) as a novel tool for evaluating dietary P load based on P bioavailability; we also evaluated the effect of continuous intake of different PI foods in mixed meals on serum intact fibroblast growth factor 23 concentration.
Design and Methods: A 2-stage crossover study was conducted: Study 1: 20 healthy participants consumed 10 different foods containing 200 mg of P, and the PI was calculated from the area under the curve of a time versus serum P concentration curve; Study 2: 10 healthy participants consumed 4 different test meals (low, medium, or high PI meals or a control) over a 5-day period.
Results: Study 1 showed milk and dairy products had high PI values, pork and ham had medium PI values, and soy and tofu had low PI values. In Study 2, ingestion of high PI test meals showed higher fasting serum intact fibroblast growth factor 23 levels and lower serum 1,25-dihydroxyvitamin D levels compared with ingestion of low PI test meals.
Conclusion: These findings suggest that the PI can usefully evaluate the dietary P load of various foods and may help to make appropriate food choices for dietary P restriction in CKD patients
- …