A New System Noise Measurement Method Using a 2-bit Analog-To-Digital Converter

We propose a new method to measure the system noise temperature, $T_{\rm sys}$, using a 2-bit analog-to-digital converter (ADC). The statistics of the digitized signal in a four-level quantization brings us information about the bias voltage and the variance, which reflects the power of the input signal. Comparison of the variances in {\it hot} and {\it sky} circumstances yields $T_{\rm sys}$ without a power meter. We performed test experiments using the Kagoshima 6-m radio telescope and a 2-bit ADC to verify this method. Linearity in the power-variance relation was better than 99% within the dynamic range of 10 dB. Digitally measured $T_{\rm sys}$ coincided with that of conventional measurement with a power meter in 1.8-% difference or less for elevations of $10^{\circ} - 88^{\circ}$. No significant impact was found by the bias voltages within the range between -3.7 and +12.8% with respect to the threshold voltage. The proposed method is available for existing interferometers that have a multi-level ADC, and release us from troubles caused by power meters.Comment: to appear in the Publications of the Astronomical Society of Japan, Vol.62, No.5; 12 pages, 6 figure

Far-infrared phonon-polariton dispersion probed by terahertz time-domain spectroscopy

We report observations of the intensity and phase transmission spectra related to phonon-polariton propagation using coherent far-infrared radiation for a high-quality ferroelectric bismuth titanate crystal plate. In order to determine the polariton-dispersion relation, the phase delay was determined minutely as a function of the THz radiation frequency in the region between 3 and 100 cm-1. The anisotropy of polariton dispersion relation was also successfully determined on the c plate simply by switching the polarization direction of an incident beam from E∥a to E∥b. The observed polariton dispersion relations are consistently reproduced by the calculation using Kurosawa’s formula

Improving Molecular Properties Prediction Through Latent Space Fusion

Pre-trained Language Models have emerged as promising tools for predicting molecular properties, yet their development is in its early stages, necessitating further research to enhance their efficacy and address challenges such as generalization and sample efficiency. In this paper, we present a multi-view approach that combines latent spaces derived from state-of-the-art chemical models. Our approach relies on two pivotal elements: the embeddings derived from MHG-GNN, which represent molecular structures as graphs, and MoLFormer embeddings rooted in chemical language. The attention mechanism of MoLFormer is able to identify relations between two atoms even when their distance is far apart, while the GNN of MHG-GNN can more precisely capture relations among multiple atoms closely located. In this work, we demonstrate the superior performance of our proposed multi-view approach compared to existing state-of-the-art methods, including MoLFormer-XL, which was trained on 1.1 billion molecules, particularly in intricate tasks such as predicting clinical trial drug toxicity and inhibiting HIV replication. We assessed our approach using six benchmark datasets from MoleculeNet, where it outperformed competitors in five of them. Our study highlights the potential of latent space fusion and feature integration for advancing molecular property prediction. In this work, we use small versions of MHG-GNN and MoLFormer, which opens up an opportunity for further improvement when our approach uses a larger-scale dataset.Comment: 8 Pages, 4 Figures - Submited to the AI4Science Workshop - Neurips 202

トランスフェリンを介する鉄の細胞内取り込み機序 ―特に肝細胞への取り込みにおける内皮細胞の関与について―

Transferrin (Tf) is thought to play a pivotal role in iron metabolism of various kinds of cells. Tf has specific receptors on the surface of the cells that require iron. Tf-receptor binding is followed by internalization through a system of coated pits and vesicles. The rapid decline of pH of these vesicles leads to the release and sequestration of iron by the cell. Apotransferrin-receptor complex returns to the cell surface, where under neutral pH conditions, apotransferrin is dissociated from the receptor. Recent advances in cellular and molecular biology, gene cloning and monoclonal antibody technique have elucidated many features of these processes at a molecular level. These advances are briefly reviewed, and particularly, our own observations concerning endothelial mediation of uptake of Tf by hepatocytes are discussed.トランスフェリン（Tf）は鉄代謝において重要な役割を担っている。鉄を必要とする細胞の表面には，Tfの特異的受容体が存在し，Ffは受容体との結合に引き続いて，coated　pitsとcoated　vesiclesを介して細胞内に取り込まれる（internalization）。Vesicle内での急速なpHの低下にともない，鉄はTfから分離し，細胞内で分画される。一方，鉄を失ったTf（アポTf）は受容体と結合したまま細胞表面にもどり，中性のpHのもとで受容体から解離する。最近の細胞・分子生物学の進歩，遺伝子クローニング，ならびにモノクローナル抗体の開発により，分子レベルで鉄代謝経路が解明されつつある。今回，これまでの主要な知見をまとめ，特に，最近筆者らの研究により明らかとなった，肝の鉄代謝における内皮細胞の役割について考察した

Peptide-conjugate antisense based splice-correction for Duchenne muscular dystrophy and other neuromuscular diseases

Duchenne muscular dystrophy (DMD) is an X-linked disorder characterized by progressive muscle degeneration, caused by the absence of dystrophin. Exon skipping by antisense oligonucleotides (ASOs) has recently gained recognition as therapeutic approach in DMD. Conjugation of a peptide to the phosphorodiamidate morpholino backbone (PMO) of ASOs generated the peptide-conjugated PMOs (PPMOs) that exhibit a dramatically improved pharmacokinetic profile. When tested in animal models, PPMOs demonstrate effective exon skipping in target muscles and prolonged duration of dystrophin restoration after a treatment regime. Herein we summarize the main pathophysiological features of DMD and the emergence of PPMOs as promising exon skipping agents aiming to rescue defective gene expression in DMD and other neuromuscular diseases. The listed PPMO laboratory findings correspond to latest trends in the field and highlight the obstacles that must be overcome prior to translating the animal-based research into clinical trials tailored to the needs of patients suffering from neuromuscular diseases

Behaviors of dissolved and particulate Co, Ni, Cu, Zn, Cd and Pb during a mesoscale Fe enrichment experiment (SEEDS II) in the western North Pacific

During mesoscale Fe enrichment (SEEDS II) in the western North Pacific ocean, we investigated dissolved and particulate Co, Ni, Cu, Zn, Cd and Pb in seawater from both field observation and shipboard bottle incubation of a natural phytoplankton assemblage with Fea ddition. Before the Fe enrichment, strong correlations between dissolved trace metals (Ni, Zn and Cd) and PO43-, and between particulate trace metals (Ni, Zn and Cd) and chlorophyll-a were obtained, suggesting that biogeochemical cycles mainly control the distributions of Ni, Zn and Cd in the study area. Average concentrations of dissolved Co, Ni, Cu, Zn, Cd and Pb in the surface mixed layer (0–20m) were 70 pM, 4.9, 2.1, 1.6, 0.48 nM and 52 pM, respectively, and those for the particulate species were 1.7 pM, 0.052, 0.094, 0.46, 0.037 nM and 5.2 pM, respectively. After Fe enrichment, chlorophyll-a increased 3 fold (up to 3 mg/L) during developing phases of the bloom (12 days). Mesozooplankton biomass also increased. Particulate Co, Ni, Cu and Cd inside the patch increase in the concentrations, but there were no analytically significant differences between concentrations inside and outside the patch. The bottle incubation with Fe addition (1 nM) showed an increase in chlorophyll-a (8.9 mg/L) and raised the particulate fraction up to 3–45% for all the metals, accompanying changes in Si/P, Zn/P and Cd/P. These results suggest that Fe addition lead to changes in biogeochemical cycling of trace metals. The comparison between the mesoscale Fe enrichment and the bottle incubation experiment suggests that although Fe was a limiting factor for the growth of phytoplankton, the enhanced biomass of mesozooplankton also limited the growth of phytoplankton and the transformation of trace metal speciation during the mesoscale Fe enrichment. Sediment trap data and the elemental ratios taken up by phytoplankton suggest that export loss was another reason that no detectable change in the concentrations of particulate trace metals was observed during the mesoscale Fe enrichment