On Measuring the Relative Importance of Explanatory Variables in a Logistic Regression

A search is described for valid methods of assessing the importance of explanatory variables in logistic regression, motivated by earlier work on the relationship between corporate governance variables and the issuance of restricted voting shares (RSF). The methods explored are adaptations of Pratt’s (1987) approach for measuring variable importance in simple linear regression, which is based on a special partition of R2. Pseudo-R2 measures for logistic regression are briefly reviewed, and two measures are selected which can be partitioned in a manner analogous to that used by Pratt. One of these is ultimately selected for the variable importance analysis of the RSF data based on its small sample stability. Confidence intervals for variable importance are obtained using the bootstrap method, and used to draw conclusions regarding the relative importance of the corporate governance variables

Topological Dirac Semimetal Na3Bi Films in the Ultrathin Limit via Alternating Layer Molecular Beam Epitaxy

Ultrathin films of Na3Bi on insulating substrates are desired for opening a bulk band gap and generating the quantum spin Hall effect from a topological Dirac semimetal, though continuous films in the few nanometer regime have been difficult to realize. Here, we utilize alternating layer molecular beam epitaxy (MBE) to achieve uniform and continuous single crystal films of Na3Bi(0001) on insulating Al2O3(0001) substrates and demonstrate electrical transport on films with 3.8 nm thickness (4 unit cells). The high material quality is confirmed through in situ reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). In addition, these films are employed as seed layers for subsequent growth by codeposition, leading to atomic layer-by-layer growth as indicated by RHEED intensity oscillations. These material advances facilitate the pursuit of quantum phenomena in thin films of Dirac semimetals.Comment: 11 pages, 5 figure

Interplay between motility and cell-substratum adhesion in amoeboid cells

The effective migration of amoeboid cells requires a fine regulation of cell-substratum adhesion. These entwined processes have been shown to be regulated by a host of biophysical and biochemical cues. Here, we reveal the pivotal role played by calcium-based mechanosensation in the active regulation of adhesion resulting in a high migratory adaptability. Using mechanotactically driven Dictyostelium discoideum amoebae, we uncover the existence of optimal mechanosensitive conditions—corresponding to specific levels of extracellular calcium—for persistent directional migration over physicochemically different substrates. When these optimal mechanosensitive conditions are met, noticeable enhancement in cell migration directionality and speed is achieved, yet with significant differences among the different substrates. In the same narrow range of calcium concentrations that yields optimal cellular mechanosensory activity, we uncovered an absolute minimum in cell-substratum adhesion activity, for all considered substrates, with differences in adhesion strength among them amplified. The blocking of the mechanosensitive ion channels with gadolinium—i.e., the inhibition of the primary mechanosensory apparatus—hampers the active reduction in substrate adhesion, thereby leading to the same undifferentiated and drastically reduced directed migratory response. The adaptive behavioral responses of Dictyostelium cells sensitive to substrates with varying physicochemical properties suggest the possibility of novel surface analyses based on the mechanobiological ability of mechanosensitive and guidable cells to probe substrates at the nanometer-to-micrometer level.SUTD-MIT International Design Centre (IDC) (IDG31400104

The effect of information management system on the production quality

Acylhydrazones of 2,3-dihydroxybenzaldehyde are easily accessible and afford heterodinuclear helicates; the self-assembly is specific when the resulting coordination compounds are neutral in charge.Chemistry, MultidisciplinarySCI(E)30ARTICLE101195-119

Effect of module degradation on inverter sizing

The effect of amorphous Silicon (a-Si) module degradation on inverter sizing is investigated in this paper to identify appropriate sizing ratios even if only undegraded data-sheet values are available. The seasonal degradation and annealing pattern of a-Si modules requires special attention to the sizing of inverters for these devices, as is demonstrated in this paper for three types of modules with different degradation rates. The efficiency of the inverters depends on the sizing ratio as well as the DC input voltage. Here data of an inverter with relatively dependence on operating voltage is used. As modules degrade, the optimum ratio of system rated power with respect to inverter nominal power increases by 10 to 15% for the specific inverter. Considering the module life-time, the inverter size chosen to be matched to the degraded power and voltage rating achieves high efficiency over the life-time of the modules, while the inverter chosen to match initial values, as given by some manufacturers on their datasheets, can add about ten percent losses to the operation

Transport Spectroscopy of Sublattice-Resolved Resonant Scattering in Hydrogen-Doped Bilayer Graphene

We report the experimental observation of sublattice-resolved resonant scattering in bilayer graphene by performing simultaneous cryogenic atomic hydrogen doping and electron transport measurements in an ultrahigh vacuum. This allows us to monitor the hydrogen adsorption on the different sublattices of bilayer graphene without atomic-scale microscopy. Specifically, we detect two distinct resonant scattering peaks in the gate-dependent resistance, which evolve as a function of the atomic hydrogen dosage. Theoretical calculations show that one of the peaks originates from resonant scattering by hydrogen adatoms on the a sublattice (dimer site) while the other originates from hydrogen adatoms on the beta sublattice (nondimer site), thereby enabling a method for characterizing the relative sublattice occupancy via transport measurements. Utilizing this new capability, we investigate the adsorption and thermal desorption of hydrogen adatoms via controlled annealing and conclude that hydrogen adsorption on the beta sublattice is energetically favored. Through site-selective desorption from the alpha sublattice, we realize hydrogen doping with adatoms primarily on a single sublattice, which is highly desired for generating ferromagnetism

Designing Smart Services: A System Dynamics-Based Business Modeling Method for IoT-Enabled Maintenance Services

This paper reports on a design science research project aiming to develop a method to support business decision-making regarding IoT-enabled maintenance services for Original Equipment Manufacturers (OEMs). Often, these OEMs remain reluctant to make full use of recent advances in the Internet of Things (IoT), sensor technologies and data analytics for providing services on installed equipment with Asset Owners (AOs). These new developments allow them to advance on their servitization journeys from selling products to selling product-centered services. The method is based on System dynamics (SD), a powerful modeling methodology to capture all these complexities in an integral, coherent and visible manner with all stakeholders. It also allows for a quantitative analysis of the business case for “smart maintenance services”. The paper describes servitization, smart (i.e. digitally enabled) mainte-nance services and then the method itself. A case study illustrates the application of the method for an OEM in the semiconductor industry