628 research outputs found
The development and test of a relationship model on system use, job learning, and impact
This exploratory study examined the role of job learning on the relationship between information
systems use and impact. Data from 308 end-users were analyzed to evaluate the relationship
between systems use, job learning, and technology impact. System use was conceptualized as
decision support, work integration, and customer service. Technology impact was conceptualized
as effect on management control, task innovation, task productivity, and customer satisfaction.
Two sets of hypotheses are presented for these relationships. Results suggest that the pattern of
system use significantly and positively influenced job learning. Job learning was found to
significantly and positively influence technology impact. We theorize that individuals learned
about their job as a result of systems usage. In turn, job learning influenced technology impact.
The study findings are discussed
Formative versus reflective measurement: Comment on Marakas, Johnson, and Clay (2007)
In a recent issue of the Journal of the Association for Information Systems, Marakas, Johnson, and Clay (2007) presented an interesting and important discussion on formative versus reflective measurement, specifically related to the measurement of the computer self-efficacy (CSE) construct. However, we believe their recommendation to measure CSE constructs using formative indicators merits additional dialogue before being adopted by researchers. In the current study we discuss why the substantive theory underlying the CSE construct suggests that it is best measured using reflective indicators. We then provide empirical evidence demonstrating how the misspecification of existing CSE measures as formative can result in unstable estimates across varying endogenous variables and research contexts. Specifically, we demonstrate how formative indicator weights are dependent on the endogenous variable used to estimate them. Given that the strength of formative indicator weights is one metric used for determining indicator retention, and adding or dropping formative indicators can result in changes in the conceptual meaning of a construct, the use of formative measurement can result in the retention of different indicators and ultimately the measurement of different concepts across studies. As a result, the comparison of findings across studies over time becomes conceptually problematic and compromises our ability to replicate and extend research in a particular domain. We discuss not only the consequences of using formative versus reflective measures in CSE research but also the broader implications this choice has on research in other domains
Clarifying the Use of Formative Measurement in the IS Discipline: The Case of Computer Self-Efficacy
The article offers insights on the use of formative measurement in the information system (IS) discipline. It focuses on the comment which warns researchers on the pitfalls of misapplying formative measures in information system domain as well as on the issues related to computer self-efficacy (CSE) and formative measurement. It then asserts that formative indicator weights are sued in determining the conceptual meaning of constructs and notes that the conceptual definition of CSE will likely differ as they are used in different research models and contexts
Cellular bases for human atrial fibrillation
Atrial fibrillation (AF) causes substantial morbidity and mortality. It may be triggered and sustained by either reentrant or nonreentrant electrical activity. Human atrial cellular refractory period is shortened in chronic AF, likely aiding reentry. The ionic and molecular mechanisms are not fully understood and may include increased inward rectifier K<sup>+</sup> current and altered Ca<sup>2+</sup> handling. Heart failure, a major cause of AF, may involve arrhythmogenic atrial electrical remodeling, but the pattern is unclear in humans. Beta-blocker therapy prolongs atrial cell refractory period; a potentially antiarrhythmic influence, but the ionic and molecular mechanisms are unclear. The search for drugs to suppress AF without causing ventricular arrhythmias has been aided by basic studies of cellular mechanisms of AF. It remains to be seen whether such drugs will improve patient treatment
Gas-induced segregation in Pt-Rh alloy nanoparticles observed by in-situ Bragg coherent diffraction imaging
Bimetallic catalysts can undergo segregation or redistribution of the metals
driven by oxidizing and reducing environments. Bragg coherent diffraction
imaging (BCDI) was used to relate displacement fields to compositional
distributions in crystalline Pt-Rh alloy nanoparticles. 3D images of internal
composition showed that the radial distribution of compositions reverses
partially between the surface shell and the core when gas flow changes between
O2 and H2. Our observation suggests that the elemental segregation of
nanoparticle catalysts should be highly active during heterogeneous catalysis
and can be a controlling factor in synthesis of electrocatalysts. In addition,
our study exemplifies applications of BCDI for in situ 3D imaging of internal
equilibrium compositions in other bimetallic alloy nanoparticles
An infrared, Raman, and X-ray database of battery interphase components
Further technological advancement of both lithium-ion and emerging battery
technologies can be catalyzed by an improved understanding of the chemistry and
working mechanisms of the solid electrolyte interphases (SEIs) that form at
electrochemically active battery interfaces. However, collecting and
interpreting spectroscopy results of SEIs is difficult for several reasons,
including the chemically diverse composition of SEIs. To address this
challenge, we herein present a vibrational spectroscopy and X-ray diffraction
data library of ten suggested SEI chemical constituents relevant to both
lithium-ion and emerging battery chemistries. The data library includes
attenuated total reflectance Fourier transform infrared spectroscopy, Raman
spectroscopy, and X-ray diffraction data, collected in inert atmospheres
afforded by custom designed sample holders. The data library presented in this
work (and online repository) alleviates challenges with locating related work
that is either diffusely spread throughout the literature, or is non-existent,
and provides energy storage researchers streamlined access to vital
SEI-relevant data that can catalyse future battery research efforts.Comment: JML and RK jointly supervised this work. 26 pages, 8 figures, 8
table
Magnetic Doping and Kondo Effect in Bi2Se3 Nanoribbons
A simple surface band structure and a large bulk band gap have allowed Bi2Se3
to become a reference material for the newly discovered three-dimensional
topological insulators, which exhibit topologically-protected conducting
surface states that reside inside the bulk band gap. Studying topological
insulators such as Bi2Se3 in nanostructures is advantageous because of the high
surface-to-volume ratio, which enhances effects from the surface states;
recently reported Aharonov-Bohm oscillation in topological insulator
nanoribbons by some of us is a good example. Theoretically, introducing
magnetic impurities in topological insulators is predicted to open a small gap
in the surface states by breaking time-reversal symmetry. Here, we present
synthesis of magnetically-doped Bi2Se3 nanoribbons by vapor-liquid-solid growth
using magnetic metal thin films as catalysts. Although the doping concentration
is less than ~ 2%, low-temperature transport measurements of the Fe-doped
Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K,
confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The
capability to dope topological insulator nanostructures magnetically opens up
exciting opportunities for spintronics.Comment: 16 pages, 4 figure
KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide Degeneracy
We show that microlensing event KMT-2016-BLG-1107 displays a new type of
degeneracy between wide-binary and close-binary Hollywood events in which a
giant-star source envelops the planetary caustic. The planetary anomaly takes
the form of a smooth, two-day "bump" far out on the falling wing of the light
curve, which can be interpreted either as the source completely enveloping a
minor-image caustic due to a close companion with mass ratio , or
partially enveloping a major-image caustic due to a wide companion with
. The best estimates of the companion masses are both in the planetary
regime ( and ) but differ by an even larger factor than the mass ratios due to
different inferred host masses. We show that the two solutions can be
distinguished by high-resolution imaging at first light on next-generation
("30m") telescopes. We provide analytic guidance to understand the conditions
under which this new type of degeneracy can appear.Comment: 23 pages, 7 figures, accepted for publication in A
KMT-2018-BLG-1990Lb: A Nearby Jovian Planet From A Low-Cadence Microlensing Field
We report the discovery and characterization of KMT-2018-BLG-1990Lb, a Jovian
planet orbiting a late M dwarf
, at a distance
(D_L=1.23_{-0.43}^{+1.06}\,\kpc), and projected at times the
snow line distance, i.e., a_{\rm snow}\equiv 2.7\,\au (M/M_\odot), This is
the second Jovian planet discovered by KMTNet in its low cadence () fields, demonstrating that this population will be well
characterized based on survey-only microlensing data.Comment: 24 pages, 7 figures, 4 table
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