Robust and Efficient Network Reconstruction in Complex System via Adaptive Signal Lasso

Network reconstruction is important to the understanding and control of collective dynamics in complex systems. Most real networks exhibit sparsely connected properties, and the connection parameter is a signal (0 or 1). Well-known shrinkage methods such as lasso or compressed sensing (CS) to recover structures of complex networks cannot suitably reveal such a property; therefore, the signal lasso method was proposed recently to solve the network reconstruction problem and was found to outperform lasso and CS methods. However, signal lasso suffers the problem that the estimated coefficients that fall between 0 and 1 cannot be successfully selected to the correct class. We propose a new method, adaptive signal lasso, to estimate the signal parameter and uncover the topology of complex networks with a small number of observations. The proposed method has three advantages: (1) It can effectively uncover the network topology with high accuracy and is capable of completely shrinking the signal parameter to either 0 or 1, which eliminates the unclassified portion in network reconstruction; (2) The method performs well in scenarios of both sparse and dense signals and is robust to noise contamination; (3) The method only needs to select one tuning parameter versus two in signal lasso, which greatly reduces the computational cost and is easy to apply. The theoretical properties of this method are studied, and numerical simulations from linear regression, evolutionary games, and Kuramoto models are explored. The method is illustrated with real-world examples from a human behavioral experiment and a world trade web.Comment: 15 pages, 8 figures, 4 table

Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser.

G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology

A numerical investigation of a wave energy harness device-water interaction system subject to the wave maker excitation in a towing tank

This paper investigates numerically a wave energy harness device-water interaction system excited by a wave maker motion in order to extract maximum wave energy. The model of the energy harness device consists of a moving coil connected to a magnetic body floating on the water surface of the towing tank. At one end of the towing tank, a wave maker produces waves to excite the device-water interaction system. The motion of the coil relative to the magnetic body produces an electromagnetic induction voltage added to an energy collection circuit, so that the kinetic energy of the coil motion is transformed to electric energy. To extract maximum energy from the wave requires a large relative motion between the coil and the magnetic body of the energy harness device. To this end, the natural frequency of the wave energy harness device should be so close to the wave frequency that a resonance of the wave energy device can be reached. Since the wave energy device floats on the water surface, its dynamic behaviour is affected by the water motion. Therefore, it is necessary to consider fluid-structure interactions to design an effective wave energy device. This problem is addressed in this paper. In this numerical simulation, the water is considered as a compressible fluid satisfying a wave equation in the water domain in association with the boundary conditions on the free surface, wall and bottom of the towing tank. The wave maker motion is simulated by a given boundary acceleration on the wet interface of the wave maker. The energy harness device is treated as a two masses connected by four springs between them. The spring stiffness can be adjusted to obtain an effective energy extraction device. On the interface between the magnetic body and the water, the equilibrium and motion consistent conditions are required. The governing equations describing the fluid-structure interaction dynamics of the integrated system are presented. A corresponding variational principle is formulated and a mixed finite element model is established. The developed computer program-FSIAP is used to complete the numerical simulations. Suitable parameters of the energy harness device are obtained. The dynamic responses of the integrated fluid-structure interaction system excited by the wave maker motions are calculated. It is shown that the designed energy harness device can extract maximum wave energy using the resonance principle. The results obtained are compared and discussed. Some guidelines for engineering applications are provided

Alterations and abnormal mitosis of wheat chromosomes induced by wheat-rye monosomic addition lines.

BACKGROUND: Wheat-rye addition lines are an old topic. However, the alterations and abnormal mitotic behaviours of wheat chromosomes caused by wheat-rye monosomic addition lines are seldom reported. METHODOLOGY/PRINCIPAL FINDINGS: Octoploid triticale was derived from common wheat T. aestivum L. 'Mianyang11'×rye S. cereale L. 'Kustro' and some progeny were obtained by the controlled backcrossing of triticale with 'Mianyang11' followed by self-fertilization. Genomic in situ hybridization (GISH) using rye genomic DNA and fluorescence in situ hybridization (FISH) using repetitive sequences pAs1 and pSc119.2 as probes were used to analyze the mitotic chromosomes of these progeny. Strong pSc119.2 FISH signals could be observed at the telomeric regions of 3DS arms in 'Mianyang11'. However, the pSc119.2 FISH signals were disappeared from the selfed progeny of 4R monosomic addition line and the changed 3D chromosomes could be transmitted to next generation stably. In one of the selfed progeny of 7R monosomic addition line, one 2D chromosome was broken and three 4A chromosomes were observed. In the selfed progeny of 6R monosomic addition line, structural variation and abnormal mitotic behaviour of 3D chromosome were detected. Additionally, 1A and 4B chromosomes were eliminated from some of the progeny of 6R monosomic addition line. CONCLUSIONS/SIGNIFICANCE: These results indicated that single rye chromosome added to wheat might cause alterations and abnormal mitotic behaviours of wheat chromosomes and it is possible that the stress caused by single alien chromosome might be one of the factors that induced karyotype alteration of wheat