Non-negative matrix factorization is a popular tool for decomposing data into feature and weight matrices under non-negativity constraints. It enjoys practical success but is poorly understood theoretically. This paper proposes an algorithm that alternates between decoding the weights and updating the features, and shows that assuming a generative model of the data, it provably recovers the gro...

A large body of work argues that scientific research increases the rate of technological advance, and with it economic growth. The precise mechanism through which science accelerates the rate of invention, however, remains an open question. Conceptualizing invention as a combinatorial search process, this paper argues that science alters inventors’ search processes, by leading them more directl...

Copper bromide catalyzed aerobic oxidative coupling of 2-aminopyridines with cinnamaldehydes directly led to the formation of 3-formyl-2-phenyl-imidazo[1,2-a]pyridines. The quantum chemical calculations were performed to trace the reaction mechanism and get insights into the possible reaction pathway. 2-Aminopyridines on coupling with cinnamaldehyde generate (E)-3-phenyl-3-(pyridin-2-ylamino)ac...

An improved method for direct oxidative coupling of o-xylene could provide streamlined access to an important monomer used in polyimide resins. The use of 2-fluoropyridine as a ligand has been found to enable unprecedented levels of chemo- and regioselectivity in this Pd-catalyzed aerobic oxidative coupling reaction. Preliminary insights have been obtained into the origin of the effectiveness o...

Abstract: We reveal theoretically chaos and its control in a semiconductor laser with delayed negative optoelectronic feedback. Under nonperiodic or sinusoidal period optoelectronic current, the semiconductor laser exhibits rich nonlinear dynamics. For a given coupling constant, chaos is shown in a semiconductor laser directly injected by external light. For a photoelectric delayed negative-fee...

We present a review of scattering models that can be used to describe the low-energy behavior of identical bosonic atoms. In the simplest models, the only degrees of freedom are atoms in the same spin state. More elaborate models have other degrees of freedom, such as atoms in other spin states or diatomic molecules. The parameters of the scattering models are specified by giving the S-wave pha...

the synthesis, spectroscopy and magnetic characterization of five new dinuclear copper(ii) complexes are described. all five compounds have the general formula [cu2(l)4(o-r)2](cl)2 or [cu2(l)2(cl)2](cl)2, in which r = ch3 or h, l=2, 3 or 4-pyridinemethanol as l2, l3 or l4, respectively. the title compounds consist of dinuclear units with bridging methoxo groups in [cu2(l4)4(o-ch3)2](cl)2, hydro...

objective: electroencephalogram is a reliable reflection of many physiological factors modulating the brain. the bispectrum is very useful for analyzing non-gaussian signals such as eeg, and detecting the quadratic phase coupling between distinct frequency components in eeg signals.the main aim of this study was to test the existence of nonlinear phase coupling within the eeg signals in a certa...