32,307 research outputs found
A 3D Printed Toolbox for Opto-Mechanical Components
Nowadays is very common to find headlines in the media where it is stated
that 3D printing is a technology called to change our lives in the near future.
For many authors, we are living in times of a third industrial revolution.
Howerver, we are currently in a stage of development where the use of 3D
printing is advantageous over other manufacturing technologies only in rare
scenarios. Fortunately, scientific research is one of them. Here we present the
development of a set of opto-mechanical components that can be built easily
using a 3D printer based on Fused Filament Fabrication (FFF) and parts that can
be found on any hardware store. The components of the set presented here are
highly customizable, low-cost, require a short time to be fabricated and offer
a performance that compares favorably with respect to low-end commercial
alternatives.Comment: 9 pages, 9 figure
Detection of the old stellar component of the major Galactic bar
We present near-IR colour--magnitude diagrams and star counts for a number of
regions along the Galactic plane. It is shown that along the l=27 b=0 line of
sight there is a feature at 5.7 +-0.7kpc with a density of stars at least a
factor two and probably more than a factor five times that of the disc at the
same position. This feature forms a distinct clump on an H vs. J-H diagram and
is seen at all longitudes from the bulge to about l=28, but at no longitude
greater than this. The distance to the feature at l=20 is about 0.5kpc further
than at l=27 and by l=10 it has merged with, or has become, the bulge. Given
that at l=27 and l=21 there is also a clustering of very young stars, the only
component that can reasonably explain what is seen is a bar with half length of
around 4kpc and a position angle of about 43+-7.Comment: 5 pages, 5 figures accepted as a letter in MNRA
How to generate pentagonal symmetry using Turing systems
We explore numerically the formation of Turing patterns in a confined circular domain with small aspect ratio. Our results show that stable fivefold patterns are formed over a well defined range of disk sizes, offering a possible mechanism for inducing the fivefold symmetry observed in early development of regular echinoids. Using this pattern as a seed, more complex biological structures can be mimicked, such as the pigmentation pattern of sea urchins and the plate arrangements of the calyxes of primitive camerate crinoids
A study of the - coupled systems
We study the strangeness meson-baryon systems to obtain improved
and amplitudes and to look for a possible resonance formation by the
- coupled interaction. We obtain amplitudes for light vector
meson-baryon systems by implementing the -, -, - channel diagrams and
a contact interaction. The pseudoscalar meson-baryon interactions are obtained
by relying on the Weinberg-Tomozawa theorem. The transition amplitudes between
the systems consisting of pseudoscalars and vector mesons are calculated by
extending the Kroll-Ruderman term for pion photoproduction replacing the photon
by a vector meson. We fix the subtraction constants required to calculate the
loops by fitting our amplitudes to the data available for the isospin 0
and 1 -wave phase shifts. We provide the scattering lengths and the total
cross sections for the and systems obtained in our model, which
can be useful in future in-medium calculations. Our amplitudes do not
correspond to formation of any resonance in none of the isospin and spin
configurations.Comment: Published version, sent to avoid confusions recently noticed by
author
- …