111,540 research outputs found
Does Scientific Progress Consist in Increasing Knowledge or Understanding?
Bird argues that scientific progress consists in increasing knowledge. DellsĂ©n objects that increasing knowledge is neither necessary nor sufficient for scientific progress, and argues that scientific progress rather consists in increasing understanding. DellsĂ©n also contends that unlike Birdâs view, his view can account for the scientific practices of using idealizations and of choosing simple theories over complex ones. I argue that DellsĂ©nâs criticisms against Birdâs view fail, and that increasing understanding cannot account for scientific progress, if acceptance, as opposed to belief, is required for scientific understanding
Subthreshold characteristics of pentacene field-effect transistors influenced by grain boundaries.
Grain boundaries in polycrystalline pentacene films significantly affect the electrical characteristics of pentacene field-effect transistors (FETs). Upon reversal of the gate voltage sweep direction, pentacene FETs exhibited hysteretic behaviours in the subthreshold region, which was more pronounced for the FET having smaller pentacene grains. No shift in the flat-band voltage of the metal-insulator-semiconductor capacitor elucidates that the observed hysteresis was mainly caused by the influence of localized trap states existing at pentacene grain boundaries. From the results of continuous on/off switching operation of the pentacene FETs, hole depletion during the off period is found to be limited by pentacene grain boundaries. It is suggested that the polycrystalline nature of a pentacene film plays an important role on the dynamic characteristics of pentacene FETs
In Defense of the Epistemic Imperative
Sample (2015) argues that scientists ought not to believe that their theories are true because they cannot fulfill the epistemic obligation to take the diachronic perspective on their theories. I reply that Sampleâs argument imposes an inordinately heavy epistemic obligation on scientists, and that it spells doom not only for scientific theories but also for observational beliefs and philosophical ideas that Samples endorses. I also delineate what I take to be a reasonable epistemic obligation for scientists. In sum, philosophers ought to impose on scientists only an epistemic standard that they are willing to impose on themselves
Scaling in the crossover from random to correlated growth
In systems where deposition rates are high compared to diffusion, desorption
and other mechanisms that generate correlations, a crossover from random to
correlated growth of surface roughness is expected at a characteristic time
t_0. This crossover is analyzed in lattice models via scaling arguments, with
support from simulation results presented here and in other authors works. We
argue that the amplitudes of the saturation roughness and of the saturation
time scale as {t_0}^{1/2} and t_0, respectively. For models with lateral
aggregation, which typically are in the Kardar-Parisi-Zhang (KPZ) class, we
show that t_0 ~ 1/p, where p is the probability of the correlated aggregation
mechanism to take place. However, t_0 ~ 1/p^2 is obtained in solid-on-solid
models with single particle deposition attempts. This group includes models in
various universality classes, with numerical examples being provided in the
Edwards-Wilkinson (EW), KPZ and Villain-Lai-Das Sarma (nonlinear molecular-beam
epitaxy) classes. Most applications are for two-component models in which
random deposition, with probability 1-p, competes with a correlated aggregation
process with probability p. However, our approach can be extended to other
systems with the same crossover, such as the generalized restricted
solid-on-solid model with maximum height difference S, for large S. Moreover,
the scaling approach applies to all dimensions. In the particular case of
one-dimensional KPZ processes with this crossover, we show that t_0 ~ nu^{-1}
and nu ~ lambda^{2/3}, where nu and lambda are the coefficients of the linear
and nonlinear terms of the associated KPZ equations. The applicability of
previous results on models in the EW and KPZ classes is discussed.Comment: 14 pages + 5 figures, minor changes, version accepted in Phys. Rev.
Corrections to the Nuclear Axial Vector Coupling in a Nuclear Medium
We examine further corrections to the time component of the axial vector
coupling constant in a nuclear medium. The dominant correction is that of
exchange currents. The corrections we examine make the remaining discrepancy
worse.Comment: 6 pages, 2 figure
Academic Support at Leeds Metropolitan Library
Leeds Metropolitanâs Library Academic Support Stream is made up of Academic Librarians and Information Services Librarians who provide academic support to the universityâs six faculties. The team use innovative methods of working together to engage students and enhance their experience. The team only formed a year ago so this is a good time to reflect on our success so far. The library service at Leeds Met is continually developing and offers new challenges and opportunities for staff providing library academic support. Innovation has even become part of our new name â âLibraries and Learning Innovationâ. We still offer all the traditions types of library academic support, but there is an increasing emphasis on finding innovative ways of supporting students and publicising what we can offer. This year the Library Academic Support Stream won a University Attitude Character and Talents Award for Future Focus
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