Ultraviolet-visible metal-semiconductor-metal photodetectors fabricated from InxGa1−xN (0≤x≤0.13)

Metal-semiconductor-metal (MSM) photodetectors have been fabricated on In_xGa_1−xN epitaxial films grown by metalorganic chemical vapor deposition within the composition range 0≤x≤0.13. The dark current and spectral response were measured for devices with a varying In mole fraction x. The devices, which had nominal finger widths and finger spacing of 5 μm, were biased with modest voltages in the range 2≤V_bias≤5 V. In general, turn-on wave-length and dark current increased with increasing x. Turn-on wavelengths ranged from λ=370 nm to 430 nm and dark current densities ranged from I_dark=2×10⁻² A/cm² (V_bias=5 V, x≈0.05) to 9×10⁴ A/cm² (V_bias=2 V, x≈0.13) depending on the In content, x, of the device active area.     

On measuring the performance of binary classifiers

If one is given two binary classifiers and a set of test data, it should be straightforward to determine which of the two classifiers is the superior. Recent work, however, has called into question many of the methods heretofore accepted as standard for this task. In this paper, we analyze seven ways of determining whether one classifier is better than another, given the same test data. Five of these are long established, and two are relative newcomers. We review and extend work showing that one of these methods is clearly inappropriate and then conduct an empirical analysis with a large number of datasets to evaluate the real-world implications of our theoretical analysis. Both our empirical and theoretical results converge strongly toward one of the newer methods.     

Toward a brief multidimensional assessment of emotional intelligence: Psychometric properties of the Emotional Quotient Inventory—Short Form.

Although several brief instruments are available for the emotional intelligence (EI) construct, their conceptual coverage tends to be quite limited. One notable exception is the short form of the Emotional Quotient Inventory (EQ-i:S), which measures multiple EI dimensions in addition to a global EI index. Despite the unique advantage offered by the inventory, psychometric properties of the EQ-i:S scores have not yet been systematically evaluated. Such an evaluation was the main goal of the present investigation. Using data from 2,508 undergraduates, the authors conducted 2 studies involving factor structure, internal reliability, 6-month temporal stability, and construct validity of the EQ-i:S responses, both for the total EQ scale and for each constituent dimension. The results supported the multidimensional measurement structure of the EQ-i:S, with each dimension producing internally consistent, temporally stable, and theoretically meaningful responses. Scores on the EQ-i:S were associated more strongly with performance on an ability test of EI and with a conceptually similar construct of alexithymia than with the broader dimensions of basic personality and explained nontrivial amounts of incremental variance in the criterion symptoms of attention deficit/hyperactivity disorder. Moreover, scores on each EQ-i:S dimension exhibited unique patterns of associations with the validation variables. The discussion highlights the advantages of the multidimensional approach in the assessment and study of EI. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Punch-through protection of SSDs in beam accidents

We have tested the effectiveness of punch-through protection (PTP) structures on n-on-p AC-coupled Silicon strip detectors using pulses from an 1064 nm IR laser, which simulate beam accidents. The voltages on the strips are measured as a function of the bias voltage and compared with the results of DC I-V measurements, which are commonly used to characterize the PTP structures. We find that the PTP structures are only effective at very large currents (several mA), and clamp the strips to much larger voltages than assumed from the DC measurements. We also find that the finite resistance of the strip implant compromises the effectiveness of the PTP structures.     

Molecular Heterojunctions of Oligo(phenylene ethynylene)s with Linear to Cruciform Framework

Electrical transport properties of molecular junctions are fundamentally affected by the energy alignment between molecular frontier orbitals (highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO)) and Fermi level (or work function) of electrode metals. Dithiafulvene (DTF) is used as substituent group to the oligo(phenylene ethynylene) (OPE) molecular wires and different molecular structures based on OPE3 backbone (with linear to cruciform framework) are achieved, with viable molecular orbitals and HOMO–LUMO energy gaps. OPE3, OPE3–DTF, and OPE3–tetrathiafulvalene (TTF) can form good self‐assembled monolayers (SAMs) on Au substrates. Molecular heterojunctions based on these SAMs are investigated using conducting probe–atomic force microscopy with different tips (Ag, Au, and Pt) and Fermi levels. The calibrated conductance values follow the sequence OPE3–TTF > OPE3–DTF > OPE3 irrespective of the tip metal. Rectification properties (or diode behavior) are observed in case of the Ag tip for which the work function is furthest from the HOMO levels of the OPE3s. Quantum chemical calculations of the transmission qualitatively agree with the experimental data and reproduce the substituent effect of DTF. Zero‐bias conductance, and symmetric or asymmetric couplings to the electrodes are investigated. The results indicate that improved fidelity of molecular transport measurements may be achieved by systematic studies of homologues series of molecular wires applying several different metal electrodes.     

3D Active Edge Silicon Detector Tests With 120 GeV Muons

3D detectors with electrodes penetrating through the silicon wafer and covering the edges were tested in the SPS beam line X5 at CERN in autumn 2003. Detector parameters including efficiency, signal-to-noise ratio, and edge sensitivity were measured using a silicon telescope as a reference system. The measured sensitive width and the known silicon width were equal within less than 10 mum.     

AUTOMATIC DELINEATION OF FUNCTIONAL RIVER REACH BOUNDARIES FOR RIVER RESEARCH AND APPLICATIONS

The river reach is a pervasive term within contemporary river research and applications. Yet, despite its prevalence, there is a notable lack of consistency in its definition. This paper identifies the presence of two broad types of reach definition within the academic literature, operational and functional, and argues that a functional definition is more suitable for applications within river research and management. A range of sequence zonation algorithms that were originally derived for geological well‐log analysis were compared for their ability to automatically identify functional reach boundaries. An analysis of variance‐based global boundary hunting algorithm was identified as the most suitable. To demonstrate the potential practical applications of automatic reach delineation methods, two case studies where functional reach boundaries have been identified were described: first, in a sequence of predicted sediment transport capacities for use in a reach‐based sediment transport model; and second, in a sequence of RHS Habitat Quality Assessment scores for identification of lengths of channel in need of habitat restoration efforts. Finally, the paper discusses how this type of functional reach identification procedure might be applied in other areas of river research and applications and how a multivariate version of a statistical zonation algorithm might prove useful in facilitating integrated catchment management by identifying reach boundaries common across all variables of interest in the system. Copyright © 2011 John Wiley & Sons, Ltd.     

Heuristic and probabilistic wind power availability estimation procedures: Improved tools for technology and site selection

The paper describes two investigative procedures to estimate wind power from measured wind velocities. Wind velocity data are manipulated to visualize the site potential by investigating the probable wind power availability and its capacity to meet a targeted demand. The first procedure is an availability procedure that looks at the wind characteristics and its probable energy capturing profile. This profile of wind enables the probable maximum operating wind velocity profile for a selected wind turbine design to be predicted. The structured procedures allow for a consequent adjustment, sorting and grouping of the measured wind velocity data taken at different time intervals and hub heights. The second procedure is the adequacy procedure that investigates the probable degree of availability and the application consequences. Both procedures are programmed using MathCAD symbolic mathematical software. The math tool is used to generate a visual interpolation of the data as well as numerical results from extensive data sets that exceed the capacity of conventional spreadsheet tools. Two sites located in Southern Ontario, Canada are investigated using the procedures. Successful implementation of the procedures supports informed decision making where a hill site is shown to have much higher wind potential than that measured at the local airport. The process is suitable for a wide spectrum of users who are considering the energy potential for either a grid-tied or off-grid wind energy system.