1,268 research outputs found
No Effect of Steady Rotation on Solid He in a Torsional Oscillator
We have measured the response of a torsional oscillator containing
polycrystalline hcp solid He to applied steady rotation in an attempt to
verify the observations of several other groups that were initially interpreted
as evidence for macroscopic quantum effects. The geometry of the cell was that
of a simple annulus, with a fill line of relatively narrow diameter in the
centre of the torsion rod. Varying the angular velocity of rotation up to
2\,rad\,s showed that there were no step-like features in the resonant
frequency or dissipation of the oscillator and no history dependence, even
though we achieved the sensitivity required to detect the various effects seen
in earlier experiments on other rotating cryostats. All small changes during
rotation were consistent with those occurring with an empty cell. We thus
observed no effects on the samples of solid He attributable to steady
rotation.Comment: 8 pages, 3 figures, accepted in J. Low Temp. Phy
Composite repetition-aware data structures
In highly repetitive strings, like collections of genomes from the same
species, distinct measures of repetition all grow sublinearly in the length of
the text, and indexes targeted to such strings typically depend only on one of
these measures. We describe two data structures whose size depends on multiple
measures of repetition at once, and that provide competitive tradeoffs between
the time for counting and reporting all the exact occurrences of a pattern, and
the space taken by the structure. The key component of our constructions is the
run-length encoded BWT (RLBWT), which takes space proportional to the number of
BWT runs: rather than augmenting RLBWT with suffix array samples, we combine it
with data structures from LZ77 indexes, which take space proportional to the
number of LZ77 factors, and with the compact directed acyclic word graph
(CDAWG), which takes space proportional to the number of extensions of maximal
repeats. The combination of CDAWG and RLBWT enables also a new representation
of the suffix tree, whose size depends again on the number of extensions of
maximal repeats, and that is powerful enough to support matching statistics and
constant-space traversal.Comment: (the name of the third co-author was inadvertently omitted from
previous version
Fast Label Extraction in the CDAWG
The compact directed acyclic word graph (CDAWG) of a string of length
takes space proportional just to the number of right extensions of the
maximal repeats of , and it is thus an appealing index for highly repetitive
datasets, like collections of genomes from similar species, in which grows
significantly more slowly than . We reduce from to
the time needed to count the number of occurrences of a pattern of
length , using an existing data structure that takes an amount of space
proportional to the size of the CDAWG. This implies a reduction from
to in the time needed to
locate all the occurrences of the pattern. We also reduce from
to the time needed to read the characters of the
label of an edge of the suffix tree of , and we reduce from
to the time needed to compute the matching
statistics between a query of length and , using an existing
representation of the suffix tree based on the CDAWG. All such improvements
derive from extracting the label of a vertex or of an arc of the CDAWG using a
straight-line program induced by the reversed CDAWG.Comment: 16 pages, 1 figure. In proceedings of the 24th International
Symposium on String Processing and Information Retrieval (SPIRE 2017). arXiv
admin note: text overlap with arXiv:1705.0864
Blood Sampling from the Tail Vein, in Comparison with Two Other Techniques, Causes Less Stress to Mice
It is important to use the optimal method for repeated blood sampling to ensure minimal stress to mice, and also to provide better pharmacokinetic and pharmacodynamic data. The aim of the present study was to compare the impact of blood sampling methods on corticosterone and adrenocorticotropic hormone (ACTH) levels in mice. Hsdwin:NMRI mice were divided into four sampling groups: control group (I), vena facialis (II), tail vein (III) and saphenous vein (IV). The first blood samples, obtained from vena facialis, tail or saphenous vein of conscious mice, were taken at time point 0. The second blood sample was taken by decapitation from groups II-IV with isoflurane anaesthesia at time point 20 min. The control group animals were anesthetized and decapitated at 20 min time point. Corticosterone levels in plasma were analyzed at time point 0 and 20 min, and ACTH at time point 20 min. Saphenous bled mice, in comparison with vena facialis and tail vein sampled mice, indicated statistically significant greater (P < 0.05) level of corticosterone at sampling point (0 min). Rising levels of corticosterone in all groups differed statistically (P < 0.05) from the control group level, indicating that all tested bleeding methods were stressful to the experimental animals. However, the tail vein bleeding method stressed statistically significantly (P < 0.05) less in comparison with vena facialis and saphenous vein bleeding. At time point 20 min, only saphenous vein bled mice showed statistically significant greater (P < 0.05) blood levels of ACTH compared to tail vein bled mice. Conditions in sampling and rising levels of corticosterone and/or ACTH level did not show direct correlation. In conclusion the results suggest that the tail bleeding method accomplished least stress to mice and next less vena facialis bleeding. Blood collection technique from the saphenous vein was the most stressful to the experimental animals.
Screening of positrons in semiconductors and insulators
Theoretical models are presented for the enhancement of the electron density at a positron in a semiconductor or insulator host. The model better suited for typical semiconductors is based on the many-body theory for the screening of a positron in electron gas. The starting point of the model for insulators is the atomic polarizability. The common parameter in both models is the high-frequency dielectric constant. Moreover, the enhancement depends on the ambient electron density in the semiconductor model and on the unit-cell volume in the insulator model. With use of the models developed, positron lifetimes in perfect semiconductor and insulator crystals have been calculated. In the calculations, three-dimensional electron densities and electrostatic potentials are obtained by atomic superposition and the fully three-dimensional positron wave functions are solved by a relaxation method. The calculated positron lifetimes agree with the experimental ones within a few picoseconds. Moreover, we have used the model to predict lifetimes of positrons trapped by lattice defects such as vacancies and vacancy clusters.Peer reviewe
Avalanches in Wood Compression
Wood is a multiscale material exhibiting a complex viscoplastic response. We study avalanches in small wood samples in compression. âWoodquakesâ measured by acoustic emission are surprisingly similar to earthquakes and crackling noise in rocks and laboratory tests on brittle materials. Both the distributions of event energies and of waiting (silent) times follow power laws. The stress-strain response exhibits clear signatures of localization of deformation to âweak spotsâ or softwood layers, as identified using digital image correlation. Even though material structure-dependent localization takes place, the avalanche behavior remains scale-free.Peer reviewe
The effects of interprofessional education - Self-reported professional competence among prehospital emergency care nursing students on the point of graduation - A cross-sectional study
The aim of the study was to investigate whether interprofessional education (IPE) and interprofessional collaboration (IPC) during the educational program had an impact on prehospital emergency care nurses' (PECN) self-reported competence towards the end of the study program. A cross-sectional study using the Nurse Professional Competence (NPC) Scale was conducted. A comparison was made between PECN students from Finland who experienced IPE and IPC in the clinical setting, and PECN students from Sweden with no IPE and a low level of IPC. Forty-one students participated (Finnish n = 19, Swedish n = 22). The self-reported competence was higher among the Swedish students. A statistically significant difference was found in one competence area; legislation in nursing and safety planning (p <0.01). The Finnish students scored significantly higher on items related to interprofessional teamwork. Both the Swedish and Finnish students' self-reported professional competence was relatively low according to the NPC Scale. Increasing IPC and IPE in combination with offering a higher academic degree may be an option when developing the ambulance service and the study program for PECNs. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe
Developing LCA-based benchmarks for sustainable consumption - for and with users
This article presents the development process of a consumer-oriented, illustrative benchmarking tool enabling consumers to use the results of environmental life cycle assessment (LCA) to make informed decisions. Active and environmentally conscious consumers and environmental communicators were identified as key target groups for this type of information. A brochure presenting the benchmarking tool was developed as an participatory, iterative process involving consumer focus groups, stakeholder workshops and questionnaire-based feedback. In addition to learning what works and what does not, detailed suggestions on improved wording and figures were obtained, as well as a wealth of ideas for future applications
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