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Magnetic actuated FR4 scanners for compact spectrometers - art. no. 699303
No full textA novel magnetic actuated polymer optical platform is integrated into a Michelson interferometer type Fourier transform infrared spectrometer. The proposed advantages of the novel platform over existing approaches, such as MEMS spectrometers, or bulky FTIR systems, include millimeter range dimensions providing a large clear aperture and enabling conventional machining for device fabrication, a controllable AC and/or DC motion both in rotational and translational modes, and low frequency operation. It has been demonstrated that the platform is capable of achieving 400 mu m DC deflection in ambient pressure in the translational mode, and a total optical scan angle exceeding 60 degrees in the resonant rotational mode. A Michelson type Fourier transform spectrometer was built using a retro-reflector bearing FR4 platform and a spectral resolution of 25cm(-1) is demonstrated with this setup. In addition, possible use of the same platform in various other spectrometer configurations and methods to improve the motion precision are discussed
Nonlinear frequency response of comb-driven microscanners
No full textAccurate prediction of the dynamic behavior of comb-driven MEMS microscanners is important to optimize the actuator and structure design. In this paper, a numerical and an analytical model for the dynamic analysis of comb-driven microscanners under different excitation schemes are presented. The numerical model is based on a second order nonlinear differential equation. Due to the nature of the torque function, this governing equation of motion is a parametric nonlinear ODE, which exhibits hysteretic frequency domain behavior and subharmonic oscillations. Experimental results and approximate analytical expressions for this nonlinear torque function of the comb-drive are presented. Amplitude and phase relationship between the excitation signal and the resultant oscillations at different excitation frequencies are measured and we show that they are in close agreement with the numerical simulations. Analytical model uses perturbation methods to reach approximate close-form expressions for the dynamic behavior of the device in the first parametric resonance region. It is also utilized to predict the stability regions on the frequency-excitation voltage plane, where the device exhibit hysterical characteristics. Analytical and numerical modeling approaches proposed in this paper provides a simple yet powerful way to analyze the nonlinear frequency response of comb-driven actuators and simplify the design process for a microscanner based system
Engineering molecular machines
No full textBiological molecular motors use chemical energy, mostly in the form of ATP hydrolysis, and convert it to mechanical energy. Correlated thermal fluctuations are essential for the function of a molecular machine and it is the hydrolysis of ATP that modifies the correlated fluctuations of the system. Correlations are consequences of the molecular architecture of the protein. The idea that synthetic molecular machines may be constructed by designing the proper molecular architecture is challenging. In their paper, Sarkar et al (2016 New J. Phys. 18 043006) propose a synthetic molecular motor based on the coarse grained elastic network model of proteins and show by numerical simulations that motor function is realized, ranging from deterministic to thermal, depending on temperature. This work opens up a new range of possibilities of molecular architecture based engine design
PRISM: protein interactions by structural matching
No full textPrism (http://gordion.hpc.eng.ku.edu.tr/prism) is a website for protein interface analysis and prediction of putative protein-protein interactions. It is composed of a database holding protein interface structures derived from the Protein Data Bank (PDB). The server also includes summary information about related proteins and an interactive protein interface viewer. A list of putative protein-protein interactions obtained by running our prediction algorithm can also be accessed. These results are applied to a set of protein structures obtained from the PDB at the time of algorithm execution (January 2004). Users can browse through the non-redundant dataset of representative interfaces on which the prediction algorithm depends, retrieve the list of similar structures to these interfaces or see the results of interaction predictions for a particular protein. Another service provided is interactive prediction. This is done by running the algorithm for user input structures
A longitudinal analysis of customer satisfaction and share of wallet: Investigating the moderating effect of customer characteristics
No full textCustomer loyalty is an important strategic objective for all managers. Research has investigated the relationship between custom̀er satisfaction and loyalty in various contexts. However, these predominantly cross-sectional studies have focused on customer retention as the primary measure of loyalty. There has been little investigation into the impact on share of wallet. Using data from the Canadian banking industry, this research aims to (1) provide the first longitudinal examination of the impact of changes in customer satisfaction on changes in share of wallet and (2) determine the moderating effects of customer age, income, education, expertise, and length of relationship. Data from 4319 households using 12,249 observations over a five-year period indicate a positive relationship between changes in satisfaction and share of wallet. In particular, the initial satisfaction level and the conditional percentile of change in satisfaction significantly correspond to changes in share of wallet. Two variables, income and length of the relationship, negatively moderate this relationship. Other demographic and situational characteristics have no impact
The role of market orientation in advertising spending during economic collapse: the case of Turkey in 2001
No full textThe authors investigate the role of market orientation in advertising spending during economic contraction. They use the 2001 economic collapse in Turkey as the empirical context in which to test hypotheses regarding why some firms increase their advertising spending in a contraction period while the majority of firms cut back. Analyzing market orientation at the level of its intelligence and responsiveness facets, they find the responsiveness facet to be positively associated with increases in advertising spending but observe the intelligence facet to be negatively associated with advertising spending. Importantly, positive shifts in advertising spending during the economic contraction predict better subsequent business performance. The opposing roles of the intelligence and responsiveness facets disappear in a subsequent economic expansion period. These findings have managerial and theoretical implications. Firms that nurture the responsiveness facet of market orientation during economic contractions go against the tide to increase their advertising spending and experience the performance benefits that such countercyclical actions can amass
Pseudounitary operators and pseudounitary quantum dynamics
No full textWe consider pseudounitary quantum systems and discuss various properties of pseudounitary operators. In particular we prove a characterization theorem for block-diagonalizable pseudounitary operators with finite-dimensional diagonal blocks. Furthermore, we show that every pseudounitary matrix is the exponential of i=root-1 times a pseudo-Hermitian matrix, and determine the structure of the Lie groups consisting of pseudounitary matrices. In particular, we present a thorough treatment of 2x2 pseudounitary matrices and discuss an example of a quantum system with a 2x2 pseudounitary dynamical group. As other applications of our general results we give a proof of the spectral theorem for symplectic transformations of classical mechanics, demonstrate the coincidence of the symplectic group Sp(2n) with the real subgroup of a matrix group that is isomorphic to the pseudounitary group U(n,n), and elaborate on an approach to second quantization that makes use of the underlying pseudounitary dynamical groups
Geometric phase for non-Hermitian Hamiltonians and its holonomy interpretation
No full textFor an arbitrary possibly non-Hermitian matrix Hamiltonian H that might involve exceptional points, we construct an appropriate parameter space m and line bundle L-n over m such that the adiabatic geometric phases associated with the eigenstates of the initial Hamiltonian coincide with the holonomies of L-n. We examine the case of 2 X 2 matrix Hamiltonians in detail and show that, contrary to claims made in some recent publications, geometric phases arising from encircling exceptional points are generally geometrical and not topological in nature
Automated, quantitative cognitive/behavioral screening of mice: for genetics, pharmacology, animal cognition and undergraduate instruction
No full textWe describe a high-throughput, high-volume, fully automated, live-in 24/7 behavioral testing system for assessing the effects of genetic and pharmacological manipulations on basic mechanisms of cognition and learning in mice. A standard polypropylene mouse housing tub is connected through an acrylic tube to a standard commercial mouse test box. The test box has 3 hoppers, 2 of which are connected to pellet feeders. All are internally illuminable with an LED and monitored for head entries by infrared (IR) beams. Mice live in the environment, which eliminates handling during screening. They obtain their food during two or more daily feeding periods by performing in operant (instrumental) and Pavlovian (classical) protocols, for which we have written protocol-control software and quasi-real-time data analysis and graphing software. The data analysis and graphing routines are written in a MATLAB-based language created to simplify greatly the analysis of large time-stamped behavioral and physiological event records and to preserve a full data trail from raw data through all intermediate analyses to the published graphs and statistics within a single data structure. The data-analysis code harvests the data several times a day and subjects it to statistical and graphical analyses, which are automatically stored in the "cloud" and on in-lab computers. Thus, the progress of individual mice is visualized and quantified daily. The data-analysis code talks to the protocol-control code, permitting the automated advance from protocol to protocol of individual subjects. The behavioral protocols implemented are matching, autoshaping, timed hopper-switching, risk assessment in timed hopper-switching, impulsivity measurement, and the circadian anticipation of food availability. Open-source protocol-control and data-analysis code makes the addition of new protocols simple. Eight test environments fit in a 48 in x 24 in x 78 in cabinet; two such cabinets (16 environments) may be controlled by one computer
Free-running ground-based photometric array imaging of transient luminous events
No full textWe present observations of transient luminous events (TLEs) recorded during a summer TLE observation campaign in 2008 at Langmuir Laboratory near Socorro, New Mexico. The campaign featured observations made by a free-running, ground-based multianode photometric array called the Photometric Imager of Precipitated Electron Radiation (PIPER). As a photometric array, PIPER has high (40 mu s) temporal resolution and enough spatial resolution (16 anodes per photometer) to make it particularly useful in the study of fast TLEs like elves and halos. As a free-running instrument, there are no missed detections and no unwanted sampling bias introduced by triggering. As a ground-based instrument, it can follow individual storms over the course of their lifetime rather than randomly sampling over large numbers of storms as required by space-based instruments. During the campaign, 143 sprites, 803 elves, and 166 halos were observed over six storms, resulting in averaged elve-to-sprite and halo-to-sprite occurrence ratios of 5.6:1 and 1.2:1, respectively. There was considerable variability in the elve-to-sprite occurrence ratio from storm to storm, ranging from a low of 3.7:1 to a high of 13.4:1. Overall, 78.2% of the elves and 55.4% of the halos were associated with negative cloud-to-ground lightning strikes (-CGs); no sprites associated with -CGs were observed. Additionally, 40 events in which pairs of elves occur in rapid succession, events we refer to as elve doublets, were observed in several storms. The duration between elves in the elve doublet events was typically 120 mu s. The causative mechanism for these events is still under deliberation