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For 6-DoF grasp detection, simulated data is expandable to train more powerful model, but it faces the challenge of the large gap between simulation and real world. Previous works bridge this gap with a sim-to-real way. However, this way explicitly or implicitly forces the simulated data to adapt to the noisy real data when training grasp detectors, where the positional drift and structural distortion within the camera noise will harm the grasp learning. In this work, we propose a Real-to-Sim framework for 6-DoF Grasp detection, named R2SGrasp, with the key insight of bridging this gap in a real-to-sim way, which directly bypasses the camera noise in grasp detector training through an inference-time real-to-sim adaption. To achieve this real-to-sim adaptation, our R2SGrasp designs the Real-to-Sim Data Repairer (R2SRepairer) to mitigate the camera noise of real depth maps in data-level, and the Real-to-Sim Feature Enhancer (R2SEnhancer) to enhance real features with precise simulated geometric primitives in feature-level. To endow our framework with the generalization ability, we construct a large-scale simulated dataset cost-efficiently to train our grasp detector, which includes 64,000 RGB-D images with 14.4 million grasp annotations. Sufficient experiments show that R2SGrasp is powerful and our real-to-sim perspective is effective. The real-world experiments further show great generalization ability of R2SGrasp. Project page is available on https://isee-laboratory.github.io/R2SGrasp.

Robotic grasping in clutters is a fundamental task in robotic manipulation. In this work, we propose an economic framework for 6-DoF grasp detection, aiming to economize the resource cost in training and meanwhile maintain effective grasp performance. To begin with, we discover that the dense supervision is the bottleneck of current SOTA methods that severely encumbers the entire training overload, meanwhile making the training difficult to converge. To solve the above problem, we first propose an economic supervision paradigm for efficient and effective grasping. This paradigm includes a well-designed supervision selection strategy, selecting key labels basically without ambiguity, and an economic pipeline to enable the training after selection. Furthermore, benefit from the economic supervision, we can focus on a specific grasp, and thus we devise a focal representation module, which comprises an interactive grasp head and a composite score estimation to generate the specific grasp more accurately. Combining all together, the EconomicGrasp framework is proposed. Our extensive experiments show that EconomicGrasp surpasses the SOTA grasp method by about 3AP on average, and with extremely low resource cost, for about 1/4 training time cost, 1/8 memory cost and 1/30 storage cost. Our code is available at https://github.com/iSEE-Laboratory/EconomicGrasp., Comment: 19 pages, 7 figures. Accepted in ECCV 2024!

The recent discovery of superconductivity in hydrogen-rich compounds has garnered significant experimental and theoretical interest because of the record-setting critical temperatures. As the direct observation of the superconducting (SC) gap in these superhydrides is rare, the underlying mechanism behind its occurrence has yet to be settled down. Here, we report a successful synthesis of the $\textit{P6$_3$}$/$\textit{mmc}$ phase of CeH$_9$ that exhibits the SC transition with SC critical temperature of about 100 K at a pressure of about 100 GPa. The observation of the zero electrical resistance and the critical current demonstrates that the SC phase is realized in Ce-based superhydride. Quasiparticle scattering spectroscopy (QSS) reveals the Andreev reflection at zero bias voltage, a hallmark of superconductivity, in the differential conductance. The obtained SC gap-to-$\textit{T}$$_c$ ratio of 4.36 and temperature dependence of SC gap are consistent with the prediction from the Bardeen-Cooper-Schrieffer theory with a moderate coupling strength. The successful realization of QSS under Megabar conditions is expected to provide a desired route to the study of the mechanism of superconductivity as well as the establishment of the SC phase in superhydride high-$\textit{T}$$_c$ systems., Comment: 20 pages, 4 figures

Based on the Rb$^+$-Rb hybrid trap, we investigate the effect of ion-atom elastic collisions on the number and temperature of the remaining atoms. We measured the remaining atomic number and temperature as a function of the wavelength and intensity of the ionization laser, and whether the ion trap was turned on. Fittings with a single exponential decay function plus an offset to the number and radius of the remaining atoms are found to be in good agreement. We found a difference in the exponential factor of different wavelengths of ionization laser with the ion trap on or off. We suppose that the presence of electrons affects ion-atom collisions through disorder-induced heating. Our research contributes to a better understanding of how ultracold neutral plasma evolves, particularly the subsequent kinetics of atomic processes, which also serves as a useful reference for high-energy-density plasma., Comment: 14 figures, 9 pages

Polyatomic cations $^{87}$Rb$_M^+$ ($M$ = 2, 3,$\ldots$) have been produced by cascade two-body ion-atom reactive collisions in the two-step CW-laser photoionization of laser-cooled $^{87}$Rb atoms and accumulated in the ion trap. Using resonant-excitation mass spectrometry and resonant excitation-assisted time-of-flight mass spectrometry, we directly observed and distinguished the charged reaction products. We experimentally verified the cascade generation and cascade dissociation of $^{87}$Rb$_M^+$. The populations of $^{87}$Rb$_M^+$ are quantitatively investigated by solving the rate equations. The $^{87}$Rb$^+$-$^{87}$Rb reaction rate coefficient was derived as 9.10$\times10^{-11}$ cm$^3$/s accordingly. The methods developed here for assembling and detecting homonuclear polyatomic cations can be applied to any experiment in ion-atom hybrid traps. The present study lays the foundation for exploring atomically precise metal clusters and physics from few- to many-body perspective., Comment: 5 figures

Using exact Bethe ansatz solution, we rigorously study excitation spectra of the spin-1/2 Fermi gas (called Yang-Gaudin model) with an attractive interaction. Elementary excitations of this model involve particle-hole excitations, hole excitations and adding particles in the Fermi seas of pairs and unpaired fermions. The gapped magnon excitations in spin sector show a ferromagnetic coupling to the Fermi sea of the single fermions. By numerically and analytically solving the Bethe ansatz equations and the thermodynamic Bethe ansatz equations of this model, we obtain excitation energies for various polarizations in the phase of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like state. For a small momentum (long-wavelength limit) and in the strong interaction regime, we analytically obtained their linear dispersions with curvature corrections, effective masses as well as velocities in particle-hole excitations of pairs and unpaired fermions. Such a type of particle-hole excitations display a novel separation of collective motions of bosonic modes within paired and unpaired fermions. Finally, we also discuss magnon excitations in spin sector and the application of the Bragg spectroscopy for testing such separated charge excitation modes of pairs and single fermions., Comment: 27 pages, 12 figures, pedagogical study of collective excitations in the 1D attractive Fermi gas, added new references and corrected few typos

Diffusion-weighted imaging (DWI) in the female breast is a magnetic resonance imaging (MRI) technique, which may potentially replace or effectively complement both x-ray mammography and contrast-enhanced MR mammography. To further improve specificity of DWI in the breast, stronger and faster diffusion weighting is advantageous. With the target application in mind, the gradient coil is designed on an irregularly shaped semi-open current-carrying surface. Due to the coil former closely fitting the non-spherical target region, non-linear encoding fields become particularly advantageous for achieving locally exceptionally high gradient strengths. As the breast tissue has a predominantly isotropic cellular microstructure, the direction of the diffusion-weighting gradient may be allowed to vary within the target volume. However, due to the quadratic dependency of the b-factor on the gradient strength, variation of the gradient magnitude needs to be carefully controlled. To achieve the above design goals the corresponding multi-objective optimization problem is reformulated as a constrained optimization, allowing for flexible and precise control of the coil properties. A novel constraint is proposed limiting the gradient magnitude variation within every slice while allowing for variations both the direction of the gradient within the slice and the magnitude across the slices. The above innovations enable the design of a unilateral coil for diffusion weighting in the female breast with the local gradient strengths exceeding 1~T/m with highly homogeneous diffusion weighting for imaging in the coronal slice orientation.

The increasing tension between the different local direct measurements of the Hubble expansion rate and that inferred from the Cosmic Microwave Background observation by $\Lambda$-Cold-Dark-Matter model could be a smoking gun of new physics, if not caused by either observational systematics or local bias. We generalize previous investigation on the local bias from a local void by globally fitting the Pantheon sample over all parameters in the radial profile function of a local void described by an inhomogeneous but isotropic Lema\^{i}tre-Tolman-Bondi metric with a cosmological constant. Our conclusion strengths the previous studies that the current tension on Hubble constant cannot be saved by a local void alone., Comment: 9 pages, 5 figures, to match the published version

This paper is concerned with a nonlocal diffusion Lotka-Volterra type competition model that consisting of a native species and an invasive species in a one-dimensional habitat with free boundaries. We prove the well-posedness of the system and get a spreading-vanishing dichotomy for the invasive species. We also provide some sufficient conditions to ensure spreading success or spreading failure for the case that the invasive species is an inferior competitor or a superior competitor, respectively.

Inspired by the discovery of high temperature superconductivity in potassium-doped $p$-terphenyl, we examine the possibility of superconductivity in $p$-quaterphenyl with one more phenyl ring than $p$-terphenyl. The Meissner effect with critical temperatures ranging from 3.5 K to 120 K is found by the magnetic susceptibility measurements in $p$-quaterphenyl upon doping potassium in the condition of annealing or just pestling. The primary superconducting phase with critical temperature of 7.2 K can be reduplicated in several superconducting samples. In both the annealed and pestled superconducting samples, the observation of bipolaronic character by the Raman scattering measurements reveals the close relationship between bipolarons and superconductivity. The occurrence of superconductivity in potassium-doped $p$-quaterphenyl provides an indication that chain link organic molecules are potential candidates for high temperature superconductors., Comment: 6 pages, 3 figures

We propose a scheme for high quantum state transfer efficiency between two distant mechanical oscillators. Through coupling separately to two optical cavities connected by an optical fiber, two distant mechanical oscillators achieve a transfer efficiency closing to unity. In the process of analysis, we employed time-varying optomechanical coupling strength as a Gaussian pulse.

The superconducting, transport, and structural properties of optimally electron-doped BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$ are investigated by combining the electrical resistance and synchrotron X-ray diffraction measurements at high pressures. The superconducting transition temperature of this system is found to decrease in a similar way of the axial ratio of $c/a$ with increasing pressure but vanishing at a critical pressure of 7.5 GPa where $c/a$ has a dip and an isostructural transformation from a tetragonal to a collapsed tetragonal phase takes place. The resistance is found to obey a linear temperature dependence, evidencing the antiferromagnetic spin-fluctuations transport mechanism. The pressure effects are interpreted within the framework of pressure-induced Fermi surface topology modification in which pressure suppresses both the quasiparticle effective mass and the strength of the antiferromagnetic spin fluctuations leading to the reduction of superconductivity, accordingly. The absent superconductivity in the collapsed tetragonal phase is suggested to result from the complete suppression of the antiferromagnetic spin fluctuations., Comment: 8 pages, 6 figures

In this paper, we consider the problem of exploring structural regularities of networks by dividing the nodes of a network into groups such that the members of each group have similar patterns of connections to other groups. Specifically, we propose a general statistical model to describe network structure. In this model, group is viewed as hidden or unobserved quantity and it is learned by fitting the observed network data using the expectation-maximization algorithm. Compared with existing models, the most prominent strength of our model is the high flexibility. This strength enables it to possess the advantages of existing models and overcomes their shortcomings in a unified way. As a result, not only broad types of structure can be detected without prior knowledge of what type of intrinsic regularities exist in the network, but also the type of identified structure can be directly learned from data. Moreover, by differentiating outgoing edges from incoming edges, our model can detect several types of structural regularities beyond competing models. Tests on a number of real world and artificial networks demonstrate that our model outperforms the state-of-the-art model at shedding light on the structural features of networks, including the overlapping community structure, multipartite structure and several other types of structure which are beyond the capability of existing models., Comment: 8 pages, 5 figures

We study the bottomonium spectrum in the nonrelativistic quark model with the coupled-channel effects. The mass shifts and valence $b\bar{b}$ component are evaluated to be rather large. We find that the hadronic loop effects can be partially absorbed into a reselection of the model parameters. No bottomonium state except $\Upsilon(5\,^1S_0)$ and $\Upsilon(5\,^3S_1)$ with mass around 10890 MeV is found in the quark models both with and without coupled-channel effects, so we suggest that $Y_{b}(10890)$ is an exotic state beyond the quark model, if it is confirmed to be a new resonance. The predictions for the $\chi_b(3P)$ masses are consistent with the ATLAS measurements. If some new bottomonium-like states are observed at LHCb or SuperB in the future, we can determine whether they are conventional bottomonium or exotic states by comparing their masses with the mass spectrum predicted in our work., Comment: 29 pages, 2 figures

We calculate the decay widths of both the second and the third radial excitations of $\eta$ and $\eta'$ within the framework of $^3P_0$ model. After comparing the theoretical decay widths and decay patterns with the available experimental data of $\eta(1760)$, $X(1835)$, $X(2120)$ and $X(2370)$, we find that the interpretation of $\eta(1760)$ and $X(1835)$ as the second radial excitation of $\eta$ and $\eta'$ crucially depends on the measured mass and width of $\eta(1760)$, which is still controversial experimentally. We suggest that there may be sizable $p\bar{p}$ content in $X(1835)$. $X(2120)$ and $X(2370)$ can not be understood as the third radial excitations of $\eta$ and $\eta'$, $X(2370)$ probably is a mixture of $\eta'(4{^1}{S}{_0})$ and glueball., Comment: 20 pages, 6 figures

We report the high-resolution angle-resolved photoemission spectroscopy studies of electronic structure of EuFe2As2. The paramagnetic state data are found to be consistent with density-functional calculations. In the antiferromagnetic ordering state of Fe, our results show that the band splitting, folding, and hybridization evolve with temperature, which cannot be explained by a simple folding picture. Detailed measurements reveal that a tiny electron Fermi pocket and a tiny hole pocket are formed near (pi,pi) in the (0,0)-(pi,pi) direction, which qualitatively agree with the results of quantum oscillations, considering kz variation of Fermi surface. Furthermore, no noticeable change within the energy resolution is observed across the antiferromagnetic transition of Eu2+ ordering, suggesting weak coupling between Eu sublattice and FeAs sublattice., Comment: 7 pages, 7 figures

We report the electronic structure of the iron-chalcogenide superconductor, Fe1.04(Te0.66Se0.34), obtained with high resolution angle-resolved photoemission spectroscopy and density functional calculations. In photoemission measurements, various photon energies and polarizations are exploited to study the Fermi surface topology and symmetry properties of the bands. The measured band structure and their symmetry characters qualitatively agree with our density function theory calculations of Fe(Te0.66Se0.34), although the band structure is renormalized by about a factor of three. We find that the electronic structures of this iron-chalcogenides and the iron-pnictides have many aspects in common, however, significant differences exist near the Gamma-point. For Fe1.04(Te0.66Se0.34), there are clearly separated three bands with distinct even or odd symmetry that cross the Fermi energy (EF) near the zone center, which contribute to three hole-like Fermi surfaces. Especially, both experiments and calculations show a hole-like elliptical Fermi surface at the zone center. Moreover, no sign of spin density wave was observed in the electronic structure and susceptibility measurements of this compound., Comment: 7 pages, 9 figures. submitted to PRB on November 15, 2009, and accepted on January 6, 2010

The lepton flavor violation $\mu\to e\gamma$, $\tau\to e\gamma$, $\tau\to\mu\gamma$, $\mu\to3e$, $\tau\to3e$, $\tau\to3\mu$ and $\mu-e$ conversion in Al and Ti are studied in both the Altarelli-Feruglio $A_4$ model and the $S_4$ model of Ding. The rates of these lepton flavor violation process for the inverted hierarchy neutrino mass spectrum are enhanced considerably by the next to leading order contributions. For both models, we find that the $\mu-e$ conversion in Ti is within the precision of next generation experiments in all the parameter space considered, the $\mu-e$ conversion in Al should be observable at least in a very significant part of the parameter space, whereas $\tau\to e\gamma$, $\tau\to\mu\gamma$, $\tau\to3e$ and $\tau\to3\mu$ are below the expected future sensitivity. The detectability of $\mu\to e\gamma$ and $\mu\to3e$ in near future depends on the models and the neutrino mass spectrum. We suggest that a comprehensive consideration of the lepton flavor violation processes is important to test and distinguish both discrete flavor symmetry models., Comment: 30 pages, 13 figures

It has been shown that the communities of complex networks often overlap with each other. However, there is no effective method to quantify the overlapping community structure. In this paper, we propose a metric to address this problem. Instead of assuming that one node can only belong to one community, our metric assumes that a maximal clique only belongs to one community. In this way, the overlaps between communities are allowed. To identify the overlapping community structure, we construct a maximal clique network from the original network, and prove that the optimization of our metric on the original network is equivalent to the optimization of Newman's modularity on the maximal clique network. Thus the overlapping community structure can be identified through partitioning the maximal clique network using any modularity optimization method. The effectiveness of our metric is demonstrated by extensive tests on both the artificial networks and the real world networks with known community structure. The application to the word association network also reproduces excellent results., Comment: 9 pages, 7 figures

We extend the one pion exchange model at quark level to include the short distance contributions coming from $\eta$, $\sigma$, $\rho$ and $\omega$ exchange. This formalism is applied to discuss the possible molecular states of $D\bar{D}^{*}/\bar{D}D^{*}$, $B\bar{B}^{*}/\bar{B}B^{*}$, $DD^{*}$, $BB^{*}$, the pseudoscalar-vector systems with $C=B=1$ and $C=-B=1$ respectively. The "$\delta$ function" term contribution and the S-D mixing effects have been taken into account. We find the conclusions reached after including the heavier mesons exchange are qualitatively the same as those in the one pion exchange model. The previous suggestion that $1^{++}$ $B\bar{B}^{*}/\bar{B}B^{*}$ molecule should exist, is confirmed in the one boson exchange model, whereas $DD^{*}$ bound state should not exist. The $D\bar{D}^{*}/\bar{D}D^{*}$ system can accomodate a $1^{++}$ molecule close to the threshold, the mixing between the molecule and the conventional charmonium has to be considered to identify this state with X(3872). For the $BB^{*}$ system, the pseudoscalar-vector systems with $C=B=1$ and $C=-B=1$, near threshold molecular states may exist. These bound states should be rather narrow, isospin is violated and the I=0 component is dominant. Experimental search channels for these states are suggested., Comment: 21 pages, 11 figures, 8 tables

The proximity of ${\rm Z}^+(4430)$ to the ${\rm D^{*}\bar{D}_1}$ threshold suggests that it may be a ${\rm D^{*}\bar{D}_1}$ molecular state. The ${\rm D^{*}\bar{D}_1}$ system has been studied dynamically from quark model, and state mixing effect is taken into account by solving the multichannel Schr$\ddot{\rm o}$dinger equation numerically. We suggest the most favorable quantum number is ${\rm J^{P}=0^{-}}$, if future experiments confirm ${\rm Z}^+(4430)$ as a loosely bound molecule state. More precise measurements of ${\rm Z}^+(4430)$ mass and width, partial wave analysis are helpful to understand its structure. The analogous heavy flavor mesons ${\rm Z}^{+}_{bb}$ and ${\rm Z}^{++}_{bc}$ are studied as well, and the masses predicted in our model are in agreement with the predictions from potential model and QCD sum rule. We further apply our model to the ${\rm D\bar{D}^{*}}$ and ${\rm DD^{*}}$ system. We find the exotic ${\rm DD^{*}}$ bound molecule doesn't exist, while the $1^{++}$ ${\rm D\bar{D}^{*}}$ bound state solution can be found only if the screening mass $\mu$ is smaller than 0.17 GeV. The state mixing effect between the molecular state and the conventional charmonium should be considered to understand the nature of X(3872)., Comment: 27 pages, 6 figures

Using the P\"{o}shl-Teller approximation, we evaluate the neutrino quasinormal modes (QNMs) of a Kerr-Newman-de Sitter black hole. The result shows that for a Kerr-Newman-de Sitter black hole, massless neutrino perturbation of large $\Lambda$, positive $m$ and small value of $n$ will decay slowly., Comment: 25 pages, 13 figures