Exploring rater judging behaviour using the many-facet rasch model

Performance assessment, unlike the traditional fixed-response assessment, has features peculiar to its assessment setting (the task choice, the task processing conditions, the raters,the rating scale, and the rating procedures) that make it much more vulnerable to construct irrelevant variance (McNamara, 1997; Upshur & Turner, 1999). Of these potential sources of variability, those associated with raters are considered to be extensive and pose serious threats to the validity of ratings (Linacre, 1989; McNamara, 1996).For performance assessment to yield valid and reliable results, it is essential that these sources of variability are eliminated or minimized. This paper illustrates how sources of rater-related variability or rater effects can be identified and controlled for using the Many-facet Rasch Model.It also illustrates how the idiosyncratic rating behaviour of individual raters can be explicated through the use of this measurement model. In this illustration, the ratings of thirty-five English language instructors on 12 paragraphs written by new intake students at the Centre for Foundation Studies, IIUM were analysed using FACETS (Linacre, 2003), a computer application which implements the Many-facet Rasch Model. The results of the analysis indicate substantial differences in rater severity, and the presence of other rater effects

Charge-transfer photodissociation of adsorbed molecules via electron image states

The 248nm and 193nm photodissociation of submonolayer quantities of CH$_3$Br and CH$_3$I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from sub-vacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-- translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane--vacuum interface, and then the charge transfers from this image state to the affinity level of a co-adsorbed halomethane which then dissociates.Comment: submitted to Journal of Chemical Physic

Cation mono- and co-doped anatase TiO2_2 nanotubes: An {\em ab initio} investigation of electronic and optical properties

The structural, electronic, and optical properties of metal (Si, Ge, Sn, and Pb) mono- and co-doped anatase TiO$_{2}$ nanotubes are investigated, in order to elucidate their potential for photocatalytic applications. It is found that Si doped TiO$_{2}$ nanotubes are more stable than those doped with Ge, Sn, or Pb. All dopants lower the band gap, except the (Ge, Sn) co-doped structure, the decrease depending on the concentration and the type of dopant. Correspondingly, a redshift in the optical properties for all kinds of dopings is obtained. Even though a Pb mono- and co-doped TiO$_{2}$ nanotube has the lowest band gap, these systems are not suitable for water splitting, due to the location of the conduction band edges, in contrast to Si, Ge, and Sn mono-doped TiO$_{2}$ nanotubes. On the other hand, co-doping of TiO$_{2}$ does not improve its photocatalytic properties. Our findings are consistent with recent experiments which show an enhancement of light absorption for Si and Sn doped TiO$_{2}$ nanotubes.Comment: revised and updated, 23 pages (preprint style), 7 figures, 5 table

Detection mechanism for ferroelectric domain boundaries with lateral force microscopy

The contrast mechanism for the visualization of ferroelectric domain boundaries with lateral force microscopy is generally assumed to be caused by mechanical deformation of the sample due to the converse piezoelectric effect. We show, however, that electrostatic interactions between the charged tip and the electric fields arising from the surface polarization charges dominate the contrast mechanism. This explanation is sustained by quantitative analysis of the measured forces as well as by comparative measurements on different materials

Pneumatic capillary gun for ballistic delivery of microparticles

A pneumatic gun for ballistic delivery of microparticles to soft targets is proposed and demonstrated. The particles are accelerated by a high speed flow of Helium in a capillary tube. Vacuum suction applied to a concentric, larger diameter tube is used to divert substantially all of the flow of Helium from the gun nozzle, thereby preventing the gas from hitting and damaging the target. Speed of ejection of micron-sized gold particles from the gun nozzle, and their depth of penetration into agarose gels are reported.Comment: 7 pages, 3 figure

Nonlocal van der Waals density functional: The simpler the better

We devise a nonlocal correlation energy functional that describes the entire range of dispersion interactions in a seamless fashion using only the electron density as input. The new functional is considerably simpler than its predecessors of a similar type. The functional has a tractable and robust analytic form that lends itself to efficient self-consistent implementation. When paired with an appropriate exchange functional, our nonlocal correlation model yields accurate interaction energies of weakly-bound complexes, not only near the energy minima but also far from equilibrium. Our model exhibits an outstanding precision at predicting equilibrium intermonomer separations in van der Waals complexes. It also gives accurate covalent bond lengths and atomization energies. Hence the functional proposed in this work is a computationally inexpensive electronic structure tool of broad applicability

The Episode of the Three Leaps in Alfred Doblin's Die Drei Sprunge Des Wang-Lun

Paper by Francis Lide, Assistant Professor of German at the University of Kansa

Mitigating odors from animal facilities using biofilters

Mitigating odors from livestock sites using biofilters was addressed in this dissertation which is organized in paper format and comprises a literature review paper and two original research papers. In the first literature review paper, both the laboratory and field research from 1997 to 2008 was reviewed to give an up-to-date perspective of studies on the mitigation of odors and volatile organic compounds (VOCs) relating to agricultural facilities using biofilters. A mobile biofiter testing system was developed which can be used at field conditions to evaluate biofilter performance at variable media types, empty bed residence times (EBRT) and media moisture contents. A field study for mitigating odors and odorous compounds from a deep-pit swine finishing facility in central Iowa was conducted to test two types of wood chip media (western cedar and two inch hardwood) using the mobile biofilter testing system. The biofilter testing system was continuously operated and evaluated at different media moisture content levels and different air flow rates resulting in a variable EBRT from 1.6 to 7.3 sec. A dynamic forced-choice olfactometer was used to evaluate odor concentrations from both the control plenum and biofilter treatments. Hydrogen sulfide and ammonia concentrations were also measured from these olfactometry samples. Solid-phase microextraction fibers were used to extract VOCs from both the control plenum and biofilter treatments. Analyses of VOCs and its corresponding individual odors were carried out using a gas chromatography-mass spectrometry-olfactometry (GC-MS-O) system. Pressure drop characteristics through the biofilters packed with western cedar and hardwood media were monitored. The reduction efficiency and pressure drop characteristics obtained with the wood chip-based biofilters indicate the feasibility of farm-level applications of wood chip-based biofilters for reducing swine building odors. The results also showed that both a proper media moisture content and a minimum EBRT were critical to a successful wood chip-based biofilter

Montessori Education: What Is Its Relationship with the Emerging Worldview?

The classroom structure of traditional education has been modeled on the defining characteristics of the mechanical worldview, including linearity, hierarchy, reductionism, objectivity, outcomes, and empiricism. The advent of a participatory worldview has brought a new set of priorities including non-linearity, interdependence, process, relationship, and ecology. A Montessori classroom structure embodies these emerging characteristics. The Montessori approach is based on a non-linear developmental model. It provides a form of education that is not limited to mechanistic cognitive development, but integrally involves all aspects of human development, and is thus well-aligned with the qualities of the emerging worldview