Boundary two-parameter eight-state supersymmetric fermion model and Bethe ansatz solution

The recently introduced two-parameter eight-state $U_q[gl(3|1)]$ supersymmetric fermion model is extended to include boundary terms. Nine classes of boundary conditions are constructed, all of which are shown to be integrable via the graded boundary quantum inverse scattering method. The boundary systems are solved by using the coordinate Bethe ansatz and the Bethe ansatz equations are given for all nine cases.Comment: 11 pages, RevTex; some typos correcte

N-(4-Chloro­phen­yl)-4-(2-oxocyclo­pent­yl)butyramide

In the title compound, C15H18ClNO2, the amide group is coplanar with the chloro­phenyl group, making a dihedral angle of 1.71 (12)°. The cyclo­penta­none ring adopts a twist conformation. A weak intra­molecular C—H⋯O hydrogen bond is observed. Mol­ecules are linked into cyclic centrosymmetric dimers by paired N—H⋯O hydrogen bonds

Plateau in Monotonic Linear Interpolation -- A "Biased" View of Loss Landscape for Deep Networks

Monotonic linear interpolation (MLI) - on the line connecting a random initialization with the minimizer it converges to, the loss and accuracy are monotonic - is a phenomenon that is commonly observed in the training of neural networks. Such a phenomenon may seem to suggest that optimization of neural networks is easy. In this paper, we show that the MLI property is not necessarily related to the hardness of optimization problems, and empirical observations on MLI for deep neural networks depend heavily on biases. In particular, we show that interpolating both weights and biases linearly leads to very different influences on the final output, and when different classes have different last-layer biases on a deep network, there will be a long plateau in both the loss and accuracy interpolation (which existing theory of MLI cannot explain). We also show how the last-layer biases for different classes can be different even on a perfectly balanced dataset using a simple model. Empirically we demonstrate that similar intuitions hold on practical networks and realistic datasets.Comment: ICLR 202

Understanding Edge-of-Stability Training Dynamics with a Minimalist Example

Recently, researchers observed that gradient descent for deep neural networks operates in an ``edge-of-stability'' (EoS) regime: the sharpness (maximum eigenvalue of the Hessian) is often larger than stability threshold 2/$\eta$ (where $\eta$ is the step size). Despite this, the loss oscillates and converges in the long run, and the sharpness at the end is just slightly below $2/\eta$. While many other well-understood nonconvex objectives such as matrix factorization or two-layer networks can also converge despite large sharpness, there is often a larger gap between sharpness of the endpoint and $2/\eta$. In this paper, we study EoS phenomenon by constructing a simple function that has the same behavior. We give rigorous analysis for its training dynamics in a large local region and explain why the final converging point has sharpness close to $2/\eta$. Globally we observe that the training dynamics for our example has an interesting bifurcating behavior, which was also observed in the training of neural nets.Comment: 53 pages, 19 figure

Discovery of the transient magnetar 3XMM J185246.6+003317 near supernova remnant Kesteven 79 with XMM-Newton

We report the serendipitous discovery with XMM-Newton that 3XMM J185246.6+003317 is an 11.56 s X-ray pulsar located 1' away from the southern boundary of supernova remnant Kes 79. The spin-down rate of 3XMM J185246.6+003317 is $<1.1\times 10^{-13}$ s s$^{-1}$, which, together with the long period P=11.558714(2) s, indicates a dipolar surface magnetic field of $1.7$ Myr, and a spin-down luminosity of $<2.8\times 10^{30}$ erg s$^{-1}$. The X-ray spectrum of the source is best-fitted with a resonant Compton scattering model, and can be also adequately described by a blackbody model. The observations covering a seven month span from 2008 to 2009 show variations in the spectral properties of the source, with the luminosity decreasing from $2.7\times 10^{34}$ erg s$^{-1}$ to $4.6 \times 10^{33}$ erg s$^{-1}$, along with a decrease of the blackbody temperature from $kT\approx 0.8$ keV to $\approx0.6$ keV. The X-ray luminosity of the source is higher than its spin-down luminosity, ruling out rotation as a power source. The combined timing and spectral properties, the non-detection of any optical or infrared counterpart, together with the lack of detection of the source in archival X-ray data prior to the 2008 XMM-Newton observation, point to this source being a newly discovered transient low-B magnetar undergoing an outburst decay during the XMM-Newton observations. The non-detection by Chandra in 2001 sets an upper limit $4\times 10^{32}$ erg s$^{-1}$ to the quiescent luminosity of 3XMM J185246.6+003317. Its period is the longest among currently known transient magnetars. The foreground absorption toward 3XMM J185246.6+003317 is similar to that of Kes 79, suggesting a similar distance of $\sim$7.1 kpc.Comment: 7 pages, 4 figures, 1 table; updated to match the published versio

Impact of high-frequency pumping on anomalous finite-size effects in three-dimensional topological insulators

Lowering of the thickness of a thin-film three-dimensional topological insulator down to a few nanometers results in the gap opening in the spectrum of topologically protected two-dimensional surface states. This phenomenon, which is referred to as the anomalous finite-size effect, originates from hybridization between the states propagating along the opposite boundaries. In this work, we consider a bismuth-based topological insulator and show how the coupling to an intense high-frequency linearly polarized pumping can further be used to manipulate the value of a gap. We address this effect within recently proposed Brillouin-Wigner perturbation theory that allows us to map a time-dependent problem into a stationary one. Our analysis reveals that both the gap and the components of the group velocity of the surface states can be tuned in a controllable fashion by adjusting the intensity of the driving field within an experimentally accessible range and demonstrate the effect of light-induced band inversion in the spectrum of the surface states for high enough values of the pump.Comment: 6 pages, 3 figure

A Hyper-pixel-wise Contrastive Learning Augmented Segmentation Network for Old Landslide Detection Using High-Resolution Remote Sensing Images and Digital Elevation Model Data

As a harzard disaster, landslide often brings tremendous losses to humanity, so it's necessary to achieve reliable detection of landslide. However, the problems of visual blur and small-sized dataset cause great challenges for old landslide detection task when using remote sensing data. To reliably extract semantic features, a hyper-pixel-wise contrastive learning augmented segmentation network (HPCL-Net) is proposed, which augments the local salient feature extraction from the boundaries of landslides through HPCL and fuses the heterogeneous infromation in the semantic space from High-Resolution Remote Sensing Images and Digital Elevation Model Data data. For full utilization of the precious samples, a global hyper-pixel-wise sample pair queues-based contrastive learning method, which includes the construction of global queues that store hyper-pixel-wise samples and the updating scheme of a momentum encoder, is developed, reliably enhancing the extraction ability of semantic features. The proposed HPCL-Net is evaluated on a Loess Plateau old landslide dataset and experiment results show that the model greatly improves the reliablity of old landslide detection compared to the previous old landslide segmentation model, where mIoU metric is increased from 0.620 to 0.651, Landslide IoU metric is increased from 0.334 to 0.394 and F1-score metric is increased from 0.501 to 0.565

Dichlorido(η6-toluene)[tris­(4-methoxy­phen­yl)phosphine]ruthenium(II)

In the title compound, [RuCl2(C7H8)(C21H21O3P)], the RuII atom possesses a pseudo-octa­hedral geometry and the metrical parameters around the metallic core compare well with those of similar three-legged-piano-stool complexes