115 research outputs found
Superhumps in a Peculiar SU UMa-Type Dwarf Nova ER Ursae Majoris
We report the photometry of a peculiar SU UMa-type dwarf nova - ER UMa for
ten nights during 1998 December and 1999 March covering a complete rise to the
supermaximum and a normal outburst cycle. Superhumps have been found during the
rise to the superoutburst. A negative superhump appeared in Dec.22 light curve,
while the superhump on the next night became positive and had large amplitude
and distinct waveform from that of the previous night. In the normal outburst
we captured, superhumps with larger or smaller amplitudes seem to always exist,
although it is not necessarily true for every normal outburst. These results
show great resemblance with V1159 Ori (Patterson et al. 1995). It is more
likely that superhumps occasionally exist at essentially all phases of the
eruption cycles of ER UMa stars, which should be considered in modeling.Comment: 4 pages, 5 figures, Accepted by ApJ Letter
Minimal Turing Test and Children's Education
Considerable evidence proves that causal learning and causal understanding greatly enhance our ability to manipulate the physical world and are major factors that distinguish humans from other primates. How do we enable unintelligent robots to think causally, answer the questions raised with "why" and even understand the meaning of such questions? The solution is one of the keys to realizing artificial intelligence. Judea Pearl believes that to achieve human-like intelligence, researchers must start by imitating the intelligence of children, so he proposed a "causal inference engine" to help future artificial intelligence make causal inference, pass the Minimal Turing Test, and even become a moral subject who can discern good from evil. This study attempts to provide some insights into the development of children's education from basic assumptions and construction goals of artificial intelligence, and to reflect on the causal model of artificial intelligence through children's education
Computationally Efficient Approximations Using Adaptive Weighting Coefficients for Solving Structural Optimization Problems
With rapid development of advanced manufacturing technologies and high demands for innovative lightweight constructions to mitigate the environmental and economic impacts, design optimization has attracted increasing attention in many engineering subjects, such as civil, structural, aerospace, automotive, and energy engineering. For nonconvex nonlinear constrained optimization problems with continuous variables, evaluations of the fitness and constraint functions by means of finite element simulations can be extremely expensive. To address this problem by algorithms with sufficient accuracy as well as less computational cost, an extended multipoint approximation method (EMAM) and an adaptive weighting-coefficient strategy are proposed to efficiently seek the optimum by the integration of metamodels with sequential quadratic programming (SQP). The developed EMAM stems from the principle of the polynomial approximation and assimilates the advantages of Taylorâs expansion for improving the suboptimal continuous solution. Results demonstrate the superiority of the proposed EMAM over other evolutionary algorithms (e.g., particle swarm optimization technique, firefly algorithm, genetic algorithm, metaheuristic methods, and other metamodeling techniques) in terms of the computational efficiency and accuracy by four well-established engineering problems. The developed EMAM reduces the number of simulations during the design phase and provides wealth of information for designers to effectively tailor the parameters for optimal solutions with computational efficiency in the simulation-based engineering optimization problems
Photometry and Spectroscopy of KS Ursae Majoris during Superoutburst
We report photometric and spectroscopic observations of the SU UMa-type dwarf
novae, KS Ursae Majoris, during its 2003 February superoutburst. Modulations
with a period of day, which is 3.3% larger than the orbital
period, have been found during the superoutburst and may be positive
superhumps. A maximum trough-to-peak amplitude of around 0.3 magnitude is
determined for this superhump.
The spectra show broad, absorption-line profiles. The lines display blue and
red troughs which alternate in depth. The radial velocity curve of the
absorption wings of H has an amplitude of km s and a
phase offset of . The velocity of the binary is
km s and varies on an order of 50 km s from day to day. From
another clear evidence for a precessing eccentric disk, we obtain a solution to
an eccentric outer disk consistent with theoretical works, which demonstrates
the validity of the relation between superhumps and tidal effects. The inner
part of the disk is also eccentric as evidenced by asymmetric and symmetric
wings in the lines. Therefore, the whole disk is eccentric and the variation of
velocity and the evolutionary asymmetric line profiles could be
criterions for an precessing eccentric accretion disk.Comment: 12 pages, 8 figures, accpeted for publication in A
Comparative Profiling of Triple-Negative Breast Carcinomas Tissue Glycoproteome by Sequential Purification of Glycoproteins and Stable Isotope Labeling
Genomes shed light on the evolution of Begonia, a megaâdiverse genus
Clarifying the evolutionary processes underlying species diversification and adaptation is a key focus of evolutionary biology. Begonia (Begoniaceae) is one of the most species-rich angiosperm genera with ~2,000 species, most of which are shade-adapted. Here, we present chromosome-scale genome assemblies for four species of Begonia (B. loranthoides, B. masoniana, B. darthvaderiana, and B. peltatifolia), and whole genome shot-gun data for an additional 74 Begonia representatives to investigate lineage evolution and shade adaptation of the genus. The four genome assemblies range in size from 331.75 Mb (B. peltatifolia) to 799.83 Mb (B. masoniana), and harbor 22,059 - 23,444 protein-coding genes. Synteny analysis revealed a lineage specific whole-genome duplication (WGD) that occurred just before the diversification of the Begonia. Functional enrichment of gene families retained after WGD highlight the significance of modified carbohydrate metabolism and photosynthesis possibly linked to shade-adaptation in the genus, which is further supported by expansions of gene families involved in light perception and harvesting. Phylogenomic reconstructions and genomics studies indicate that genomic introgression has also played a role in the evolution of Begonia. Overall, this study provides valuable genomic resources for Begonia and suggests potential drivers underlying the diversity and adaptive evolution of this mega-diverse clade
The stellar velocity distribution in the solar neighbourhood
We explore the heating of the velocity distribution in the solar
neighbourhood by stochastic spiral waves. Our investigation is based on direct
numerical integration of initially circular test-particle orbits in the sheared
sheet. We confirm the conclusion of other investigators that heating by spiral
structure can explain the principal features of the age-velocity dispersion
relation and other parameters of the velocity distribution in the solar
neighbourhood. In addition, we find that heating by strong transient spirals
can naturally explain the presence of small-scale structure in the velocity
distribution (``moving groups''). Heating by spiral structure also explains why
the stars in a single velocity-space moving group have a wide range of ages, a
result which is difficult to understand in the traditional model that these
structures result from inhomogeneous star formation. Thus we suggest that old
moving groups arise from irregularities in the Galactic potential rather than
irregularities in the star-formation rate.Comment: Accepted by MNRAS for publication; 20 pages, 11 figures, mn2e.cl
Risk of breast cancer and family history of other cancers in first-degree relatives in Chinese women: a case control study
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The Molecular Mechanism of KCNE1 Modulation of KCNQ1
Long QT syndrome (LQTS) is a heart disorder that can lead to severe cardiac arrhythmias and sudden cardiac death. Hundreds of mutations in the genes (KCNQ1 and KCNE1) encoding the KCNQ1/KCNE1 channel cause LQTS. KCNQ1 contains both a voltage-sensing domain (VSD) and a pore domain (PD). KCNE1 regulates the function of the KCNQ1 channel in several ways. KCNQ1 expressed alone opens when the VSD is in an intermediate state. KCNQ1 co-expressed with KCNE1 opens mainly when the VSD is in a fully activated state. KCNE1 also drastically slows the opening and shifts the voltage dependence of opening by >40 mV of KCNQ1 channels. Using voltage clamp fluorometry, we here show that mutations of conserved residues (F232A and F279A) at the VSD-PD interface alter the VSD-PD coupling so that the mutant KCNQ1/KCNE1 channels open in the intermediate VSD state. The mutant cycle analysis suggested that F232 and F279 are interacting with each other in the KCNQ1 channel only in the presence of KCNE1. Using recent structures of KCNQ1 and KCNE beta subunits in different states, we present a novel mechanism by which KCNE1 rotates the VSD relative to the PD and affects the VSD-PD coupling of KCNQ1 channels in a non-canonical way, forcing KCNQ1/KCNE1 channels to open in the fully-activated VSD state. This would explain many of the KCNE1-induced effects on KCNQ1 channels.</p
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