Study on cosmogenic activation in copper for rare event search experiments

The rare event search experiments using germanium detectors are performed in the underground laboratories to prevent cosmic rays. However, the cosmogenic activation of the cupreous detector components on the ground will generate long half-life radioisotopes and contribute continually to the expected background level. We present a study on the cosmogenic activation of copper after 504 days of exposure at an altitude of 2469.4 m outside the China Jinping Underground Laboratory (CJPL). The specific activities of the cosmogenic nuclides produced in the copper bricks were measured using a low background germanium gamma-ray spectrometer at CJPL. The production rates at sea level, in units of nuclei/kg/day, are 18.6 \pm 2.0 for Mn-54, 9.9 \pm 1.3 for Co-56, 48.3 \pm 5.5 for Co-57, 51.8 \pm 2.5 for Co-58 and 39.7 \pm 5.7 for Co-60, respectively. Given the expected exposure history of the germanium detectors, a Monte Carlo simulation is conducted to assess the cosmogenic background contributions of the detectors' cupreous components.Comment: 6 pages, 4 figure

RocketQAv2: A Joint Training Method for Dense Passage Retrieval and Passage Re-ranking

In various natural language processing tasks, passage retrieval and passage re-ranking are two key procedures in finding and ranking relevant information. Since both the two procedures contribute to the final performance, it is important to jointly optimize them in order to achieve mutual improvement. In this paper, we propose a novel joint training approach for dense passage retrieval and passage re-ranking. A major contribution is that we introduce the dynamic listwise distillation, where we design a unified listwise training approach for both the retriever and the re-ranker. During the dynamic distillation, the retriever and the re-ranker can be adaptively improved according to each other's relevance information. We also propose a hybrid data augmentation strategy to construct diverse training instances for listwise training approach. Extensive experiments show the effectiveness of our approach on both MSMARCO and Natural Questions datasets. Our code is available at https://github.com/PaddlePaddle/RocketQA.Comment: EMNLP 202

Tetra­aqua­bis­[4-(1H-imidazol-1-yl-κN 3)benzoato]cobalt(II)

In the title compound, [Co(C10H7N2O2)2(H2O)4], the CoII atom lies on an inversion centre and displays a slightly distorted octa­hedral geometry. The coordination sphere is defined by two mutually trans N atoms from two 4-(imidazol-1-yl)benzoate ligands and the O atoms from four water mol­ecules. The crystal structure is stabilized by O—H⋯O hydrogen bonds

Merger time scale of galaxies

Abstract. In this talk, we present our recent study of galaxy mergers in a high-resolution cosmological hydro/N-body simulation with star formation, and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical results indicate, that the commonly used equation for the merger timescale given by Lacey and Cole, systematically underestimates the merger timescales for minor mergers and overestimates those for major mergers. This behavior is partly explained by the poor performance of their expression for the Coulomb logarithm, ln(/Wpri//Wsat). The two alternative forms ln(l +/Wpri//Wsat) and l/2In[l + [m^^/msnt) ] for the Coulomb logarithm can account for the mass dependence of merger timescale successfiilly, but both of them underestimate the merger time scale by a factor 2. Since ln(l + /Wpn/msat) represents the mass dependence slightly better we adopt this expression for the Coulomb logarithm. Furthermore, we find that the dependence of the merger timescale on the circularity parameter e is much weaker than the widely adopted power-law e, whereas 0.94 * e"" " + 0.60 provides a good match to the data. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models

New Differential Cryptanalysis Results for the Lightweight Block Cipher BORON

BORON is a 64-bit lightweight block cipher based on the substitution-permutation network that supports an 80-bit (BORON-80) and 128-bit (BORON-128) secret key. In this paper, we revisit the use of differential cryptanalysis on BORON in the single-key model. Using an SAT/SMT approach, we look for differentials that consist of multiple differential characteristics with the same input and output differences. Each characteristic that conforms to a given differential improves its overall probability. We also implemented the same search using Matsui\u27s algorithm for verification and performance comparison purposes. We identified high-probability differentials which were then used in key recovery attacks against BORON-80/128. We first show that the previous differential cryptanalysis attack against 9-round of BORON was at most an 8.5 round attack due to the omission of the final block XOR layer. Then, we used 8-round differentials with a probability of $2^{-58.156}$ and $2^{-62.415}$ in key recovery attacks against 9 and 10 rounds of BORON-80 and BORON-128 with time/data/memory complexities of {$2^{63.63}/2^{62}/2^{55}$ and $2^{100.28}/2^{64}/2^{71}$} respectively. Our key recovery framework provides a more accurate estimate of the attack complexity as compared to previous work. The attacks proposed in this paper are the best differential attacks against BORON-80/128 in the single-key model to date

Urban flood inundation probability assessment based on an improved Bayesian model

Urban flood inundation is spatially uncertain. To quantify this uncertainty, it is necessary to explore the spatial probability of urban flood inundation in different return periods. In this study, an urban flood spatial inundation probability assessment method based on an improved Bayesian model is proposed, which comprises three parts: data reconstruction based on undersampling; optimal Bayesian sample planning; and spatial inundation probability assessment. A case study of the central urban area of Jingdezhen City, China, is presented in this paper. The results indicate that (1) the inundation probabilities generated based on various return periods (20-, 50-, and 100-year return periods) are accurately determined and can provide more detailed inundation information. (2) The adoption of the random undersampling data reconstruction method solves the problem of an imbalanced number of inundations/noninundations during Bayesian modeling and substantially enhances the prediction accuracy compared with the traditional Bayesian modeling approach. (3) A sensitivity analysis reveals that inundation probability is sensitive to the drainage network and elevation rather than soil water retention and distance to river. With an increase in the return period, the inundation probability gradually increases. As the proposed method can quantify flood inundation uncertainty, it is valuable in supporting specific flood risk assessments

Molecular cloning and characterization of the mouse Acdp gene family

BACKGROUND: We have recently cloned and characterized a novel gene family named ancient conserved domain protein (ACDP) in humans. To facilitate the functional study of this novel gene family, we have cloned and characterized Acdp, the mouse homologue of the human ACDP gene family. RESULTS: The four Acdp genes (Acdp1, Acdp2, Acdp3 and Acdp4) contain 3,631 bp, 3,244 bp, 2,684 bp and 2,743 bp of cDNA sequences, and encode deduced proteins of 951, 874, 713 and 771 amino acids, respectively. The mouse Acdp genes showed very strong homologies (>90%) in both nucleotide and amino acid sequences to their human counterparts. In addition, both nucleotide and amino acid sequences within the Ancient Conserved Domain (ACD) are highly conserved in many different taxonomic species. Particularly, Acdp proteins showed very strong AA homologies to the bacteria CorC protein (35% AA identity with 55% homology), which is involved in magnesium and cobalt efflux. The Acdp genes are widely expressed in all tissues tested except for Acdp1, which is only highly expressed in the brain with low levels of expression in kidney and testis. Immunostaining of Acdp1 in hippocampus neurons revealed a predominant localization on the plasma membrane. CONCLUSION: The Acdp genes are evolutionarily conserved in diverse species and ubiquitously expressed throughout development and adult tissues suggesting that Acdp may be an essential gene. Acdp showed strong homology to bacteria CorC protein and predominantly localized on the plasma membrane. These results suggest that Acdp is probably a family of proteins involved in ion transport in mammalian cell