Typical Scales in the Spatial Distribution of QSOs

We present results of searching for the possible typical scales in the spatial distribution of QSOs. Our method is based on the second derivative of the two-point correlation function. This statistic is sensitive to the scale of the maximum in the spectrum $P(k)$ of the density perturbation in the universe. This maximum or bend scale can be detected as the wavelengths of the periodic component in the second derivative of the integral correlation function. For various QSO samples compiled from surveys of pencil-beam and bright QSOs, a typical scale of about 93 $\pm$ 10 h$^{-1}$Mpc for $q_0=0.5$ has been detected. This typical scale is in good agreement with that found in the spatial distributions of galaxies, clusters of galaxies, and CIV absorption systems of QSOs if $q_0$ is taken to be $\sim 0.2$. Therefore, it is likely a common or universal scale in the large scale structure traced by these objects. This result is consistent with the assumption that the typical scale comes from a characteristic scale in the spectrum of the density perturbation in the universe.Comment: 16 pages, 13 figures (available upon request), Latex, AZPH-TH/94-02, to appear in Ap.

Effect of Coating Thickness on Sound Absorption Property of Four Wood Species Commonly Used for Piano Soundboards

Effects of polyurethane (PU) coating thicknesses (0.15, 0.30, 0.45, and 0.60 mm) on sound absorption coefficients of four wood species were investigated using the standing wave ratio method with an input sound vibration frequency range set between 125 and 4000 Hz. Wood species of four specific gravity (SG) levels were Korean spruce, European spruce, Sitka spruce, and Picea brachytyla. Experimental results indicated that PU coating can significantly increase sound absorption coefficients of higher SG species such as Sitka spruce and Picea brachytyla in all tested frequency levels, but this significant increase was not observed in lower SG species such as Korean and European spruces when tested in the frequency range from 800 to 2000 Hz. Effects of coating thickness on sound absorption coefficients of four evaluated species were found to interact with wood SG values and input sound vibration frequency ranges. Specifically, coating 0.30-mm-thick PU on Korean and European spruces tends to result in significantly lower sound absorption coefficients among the ones coated with four evaluated thicknesses when tested at the frequency less than 800 Hz, but PU coating thickness resulting in lower sound absorption coefficients on Sitka spruce and Picea brachytyla was 0.15 mm. Sitka spruce and Picea brachytyla coated with 0.30- and 0.6-mm-thick PU had lower sound absorption coefficients when tested at the frequency ranging from 1000 to 2000 Hz. When tested at the frequency greater than 2500 Hz, sound absorption coefficients of four coated species increased as coating thickness increased from 0.30 to 0.60 mm with an increment of 0.15 mm, but these four species coated with three thicker PU had significantly lower sound absorption coefficients than the ones coated with 0.15-mm-thick PU. The uncoated higher SG species tended to have lower sound absorption coefficients than uncoated lower SG ones when tested in the frequency ranging from 500 to 4000 Hz, but the differences were not found when tested under the frequency less than 400 Hz. Coating four species with different thicknesses of PU could alter their SG effects on their sound absorption coefficients

FishMOT: A Simple and Effective Method for Fish Tracking Based on IoU Matching

The tracking of various fish species plays a profoundly significant role in understanding the behavior of individual fish and their groups. Present tracking methods suffer from issues of low accuracy or poor robustness. In order to address these concerns, this paper proposes a novel tracking approach, named FishMOT (Fish Multiple Object Tracking). This method combines object detection techniques with the IoU matching algorithm, thereby achieving efficient, precise, and robust fish detection and tracking. Diverging from other approaches, this method eliminates the need for multiple feature extractions and identity assignments for each individual, instead directly utilizing the output results of the detector for tracking, thereby significantly reducing computational time and storage space. Furthermore, this method imposes minimal requirements on factors such as video quality and variations in individual appearance. As long as the detector can accurately locate and identify fish, effective tracking can be achieved. This approach enhances robustness and generalizability. Moreover, the algorithm employed in this method addresses the issue of missed detections without relying on complex feature matching or graph optimization algorithms. This contributes to improved accuracy and reliability. Experimental trials were conducted in the open-source video dataset provided by idtracker.ai, and comparisons were made with state-of-the-art detector-based multi-object tracking methods. Additionally, comparisons were made with idtracker.ai and TRex, two tools that demonstrate exceptional performance in the field of animal tracking. The experimental results demonstrate that the proposed method outperforms other approaches in various evaluation metrics, exhibiting faster speed and lower memory requirements. The source codes and pre-trained models are available at: https://github.com/gakkistar/FishMO

Negative Feedback Regulation of Wnt4 Signaling by EAF1 and EAF2/U19

Previous studies indicated that EAF (ELL-associated factor) family members, EAF1 and EAF2/U19, play a role in cancer and embryogenesis. For example, EAF2/U19 may serve as a tumor suppressor in prostate cancer. At the same time, EAF2/U19 is a downstream factor in the non-canonical Wnt 4 signaling pathway required for eye development in Xenopus laevis, and along with EAF1, contributes to convergence and extension movements in zebrafish embryos through Wnt maintenance. Here, we used zebrafish embryos and mammalian cells to show that both EAF1 and EAF2/U19 were up-regulated by Wnt4 (Wnt4a). Furthermore, we found that EAF1 and EAF2/U19 suppressed Wnt4 expression by directly binding to the Wnt4 promoter as seen in chromatin immunoprecipitation assays. These findings indicate that an auto-regulatory negative feedback loop occurs between Wnt4 and the EAF family, which is conserved between zebrafish and mammalian. The rescue experiments in zebrafish embryos showed that early embryonic development required the maintenance of the appropriate levels of Wnt4a through the feedback loop. Others have demonstrated that the tumor suppressors p63, p73 and WT1 positively regulate Wnt4 expression while p21 has the opposite effect, suggesting that maintenance of appropriate Wnt4 expression may also be critical for adult tissue homeostasis and prevention against tumor initiation. Thus, the auto-regulatory negative feedback loop that controls expression of Wnt4 and EAF proteins may play an important role in both embryonic development and tumor suppression. Our findings provide the first convincing line of evidence that EAF and Wnt4 form an auto-regulatory negative feedback loop in vivo

Distinct Fermi Surface Topology and Nodeless Superconducting Gap in (Tl0.58Rb0.42)Fe1.72Se2 Superconductor

High resolution angle-resolved photoemission measurements have been carried out to study the electronic structure and superconducting gap of the (Tl$_{0.58}$Rb$_{0.42}$)Fe$_{1.72}$Se$_2$ superconductor with a T$_c$=32 K. The Fermi surface topology consists of two electron-like Fermi surface sheets around $\Gamma$ point which is distinct from that in all other iron-based compounds reported so far. The Fermi surface around the M point shows a nearly isotropic superconducting gap of $\sim$12 meV. The large Fermi surface near the $\Gamma$ point also shows a nearly isotropic superconducting gap of $\sim$15 meV while no superconducting gap opening is clearly observed for the inner tiny Fermi surface. Our observed new Fermi surface topology and its associated superconducting gap will provide key insights and constraints in understanding superconductivity mechanism in the iron-based superconductors.Comment: 4 pages, 4 figure