1,411 research outputs found
Dielectric breakdown II: Related projects at the University of Twente
In this paper an overview is given of the related activities in our group of the University of Twente. These are on thin film transistors with the inherent difficulty of making a gate dielectric at low temperature, on thin dielectrics for EEPROM devices with well-known requirements with respect to charge retention and endurance and, finally, on thin film diodes in displays with unexpected breakdown properties
Controlling the cold collision shift in high precision atomic interferometry
We present here a new method based on a transfer of population by adiabatic
passage that allows to prepare cold atomic samples with a well defined ratio of
atomic density and atom number. This method is used to perform a measurement of
the cold collision frequency shift in a laser cooled cesium clock at the
percent level, which makes the evaluation of the cesium fountains accuracy at
the level realistic. With an improved set-up, the adiabatic passage
would allow measurements of atom number-dependent phase shifts at the
level in high precision experiments.Comment: 4 pages, 3 figures, 2 table
Integrated Test Development:An integrated and incremental approach to write software of high quality
Recommended from our members
Automatic trip and mode detection with move smarter: First results from the Dutch Mobile Mobility Panel
This paper describes the performance of a smartphone app called MoveSmarter to automatically detect departure and arrival times, trip origins and destinations, transport modes, and travel purposes. The app is used in a three-year smartphone-based prompted-recall panel survey in which about 600 smartphone and non-smartphone owners participated and over 18,000 validated trips were collected during two weeks. MoveSmarter is concluded to be a promising alternative or addition to traditional trip diaries, reducing respondent burden and increasing accuracy of measurement, but there is room to improve trip and mode detection rates and the efficiency of battery consumption
Sex-Based Differences in Pneumococcal Serotype Distribution in Adults with Pneumococcal Meningitis
info:eu-repo/semantics/publishedVersio
How do Students Test Software Units?
We gained insight into ideas and beliefs on testing of students who finished an introductory course on programming without any formal education on testing. We asked students to fill in a small survey, to do four exercises and to fill in a second survey. We interviewed eleven of these students in semi-structured interviews, to obtain more in-depth insight. The main outcome is that students do not test systematically, while most of them think they do test systematically. One of the misconceptions we found is that most students can only think of test cases based on programming code. Even if no code was provided (black-box testing), students try to come up with code to base their test cases on
Collective Modes in a Dilute Bose-Fermi Mixture
We here study the collective excitations of a dilute spin-polarized
Bose-Fermi mixture at zero temperature, considering in particular the features
arising from the interaction between the two species. We show that a
propagating zero-sound mode is possible for the fermions even when they do not
interact among themselves.Comment: latex, 6 eps figure
Extended molecules and geometric scattering resonances in optical lattices
We develop a theory describing neutral atoms scattering at low energies in an
optical lattice. We show that for a repulsive interaction, as the microscopic
scattering length increases, the effective scattering amplitude approaches a
limiting value which depends only on the lattice parameters. In the case of
attractive interaction a geometric resonance occurs before reaching this limit.
Close to the resonance, the effective interaction becomes repulsive and
supports a weakly bound state, which can extend over several lattice sites.Comment: 4 pages, 1 figure, RevTe
Bose condensates in a harmonic trap near the critical temperature
The mean-field properties of finite-temperature Bose-Einstein gases confined
in spherically symmetric harmonic traps are surveyed numerically. The solutions
of the Gross-Pitaevskii (GP) and Hartree-Fock-Bogoliubov (HFB) equations for
the condensate and low-lying quasiparticle excitations are calculated
self-consistently using the discrete variable representation, while the most
high-lying states are obtained with a local density approximation. Consistency
of the theory for temperatures through the Bose condensation point requires
that the thermodynamic chemical potential differ from the eigenvalue of the GP
equation; the appropriate modifications lead to results that are continuous as
a function of the particle interactions. The HFB equations are made gapless
either by invoking the Popov approximation or by renormalizing the particle
interactions. The latter approach effectively reduces the strength of the
effective scattering length, increases the number of condensate atoms at each
temperature, and raises the value of the transition temperature relative to the
Popov approximation. The renormalization effect increases approximately with
the log of the atom number, and is most pronounced at temperatures near the
transition. Comparisons with the results of quantum Monte Carlo calculations
and various local density approximations are presented, and experimental
consequences are discussed.Comment: 15 pages, 11 embedded figures, revte
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