2,120 research outputs found
Some statistics on permutations avoiding generalized patterns
In the last decade a huge amount of articles has been published studying
pattern avoidance on permutations. From the point of view of enumeration,
typically one tries to count permutations avoiding certain patterns according
to their lengths. Here we tackle the problem of refining this enumeration by
considering the statistics "first/last entry". We give complete results for
every generalized patterns of type or as well as for some cases
of permutations avoiding a pair of generalized patterns of the above types.Comment: 5 figure
The surface accessibility of α-bungarotoxin monitored by a novel paramagnetic probe
The surface accessibility of {alpha}-bungarotoxin has been investigated by using Gd2L7, a newly designed paramagnetic NMR probe. Signal attenuations induced by Gd2L7 on {alpha}-bungarotoxin C{alpha}H peaks of 1H-13C HSQC spectra have been analyzed and compared with the ones previously obtained in the presence of GdDTPA-BMA. In spite of the different molecular size and shape, for the two probes a common pathway of approach to the {alpha}-bungarotoxin surface can be observed with an equally enhanced access of both GdDTPA-BMA and Gd2L7 towards the protein surface side where the binding site is located. Molecular dynamics simulations suggest that protein backbone flexibility and surface hydration contribute to the observed preferential approach of both gadolinium complexes specifically to the part of the {alpha}-bungarotoxin surface which is involved in the interaction with its physiological target, the nicotinic acetylcholine receptor
Enumerative Combinatorics of Intervals in the Dyck Pattern Poset
We initiate the study of the enumerative combinatorics of the intervals in the Dyck pattern poset. More specifically, we find some closed formulas to express the size of some specific intervals, as well as the number of their covering relations. In most of the cases, we are also able to refine our formulas by rank. We also provide the first results on the Möbius function of the Dyck pattern poset, giving for instance a closed expression for the Möbius function of initial intervals whose maximum is a Dyck path having exactly two peaks
Effect of grain refinement on enhancing critical current density and upper critical field in undoped MgB2 ex-situ tapes
Ex-situ Powder-In-Tube MgB2 tapes prepared with ball-milled, undoped powders
showed a strong enhancement of the irreversibility field H*, the upper critical
field Hc2 and the critical current density Jc(H) together with the suppression
of the anisotropy of all of these quantities. Jc reached 104 A/cm2 at 4.2 K and
10 T, with an irreversibility field of about 14 T at 4.2 K, and Hc2 of 9 T at
25 K, high values for not-doped MgB2. The enhanced Jc and H* values are
associated with significant grain refinement produced by milling of the MgB2
powder, which enhances grain boundary pinning, although at the same time also
reducing the connectivity from about 12% to 8%. Although enhanced pinning and
diminished connectivity are in opposition, the overall influence of ball
milling on Jc is positive because the increased density of grains with a size
comparable with the mean free path produces strong electron scattering that
substantially increases Hc2, especially Hc2 perpendicular to the Mg and B
planes.Comment: 26 pages, 9 figures, submitted to J. Appl. Phy
Thermal properties of MgB2: the effect of disorder on gap amplitudes and relaxation times of p and s bands
We present thermal conductivity and specific heat measurements on MgB2 and
Mg-AlB2 samples. Thermal properties have been analysed by using a two-gap model
in order to estimate the gap amplitudes, D(0)p and D(0)s and the intra-band
scattering rates, Gss and Gpp. As a function of Al doping and disorder D(0)s
rapidly decreases, while D(0)p is rather constant. Gss and Gpp are increased by
the disorder, being Gpp more affected than Gss.Comment: 2 pages, 3 figures, presented to the conference M2S-HTSC, 25-30 May
2003, Rio de Janeir
Project-based learning: video game development as a tool to integrate ecology, genetics, evolution and informatics
Introduction: Active, student-centered learning encourages the development of 21st century skills and competences. Many of them encourage, in addition to autonomy, interdisciplinarity. Therefore, the participation of students in the creation and not only the stimulation of the use of technologies is extremely relevant. Considering the importance of multidisciplinarity that must envolve the learning process, new approaches such as Project Based-Learning have been developed, seeking greater involvement of the students in learning-related decisions. Objective: Aiming the interdisciplinarity that the integrated educational system requires, the purpose of this study was to analyze the development of games as an integration tool, between biology and computing area. The games have been developed along with the subjects of Entrepreneurship and Practical Projects III. Methods: Classes have been held so that high school students could grasp the contents of Evolution, Genetics and Ecology, which would be the central themes of the games. Results: Groups who have chosen Evolution to work with had greater difficulty in understanding the contente whereas those who have worked with Ecology and Genetics outdid the formers. The Game Maker program stood out being the most used tool for the game’s making process. Conclusion: The acceptance of the project by the students leads to the conclusion that innovative methodologies such as project-based learning is a great tool in education, so that the groups could be more involved in class and the subjects could be linked together
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