1,292 research outputs found
The Kinematics of HH 34 from HST Images with a Nine-year Time Baseline
We study archival HST [S II] 6716+30 and Hα images of the HH 34 outflow, taken in 1998.71 and in 2007.83. The ~9 yr time baseline and the high angular resolution of these observations allow us to carry out a detailed proper-motion study. We determine the proper motions of the substructure of the HH 34S bow shock (from the [S II] and Hα frames) and of the aligned knots within ~30'' from the outflow source (only from the [S II] frames). We find that the present-day motions of the knots along the HH 34 jet are approximately ballistic, and that these motions directly imply the formation of a major mass concentration in ~900 yr, at a position similar to the one of the present-day HH 34S bow shock. In other words, we find that the knots along the HH 34 jet will merge to form a more massive structure, possibly resembling HH 34S
Reasoning about norms under uncertainty in dynamic environments
The behaviour of norm-autonomous agents is determined by their goals and the norms that are explicitly represented inside their minds. Thus, they require mechanisms for acquiring and accepting norms, determining when norms are relevant to their case, and making decisions about norm compliance. Up until now the existing proposals on norm-autonomous agents assume that agents interact within a deterministic environment that is certainly perceived. In practise, agents interact by means of sensors and actuators under uncertainty with non-deterministic and dynamic environments. Therefore, the existing proposals are unsuitable or, even, useless to be applied when agents have a physical presence in some real-world environment. In response to this problem we have developed the n-BDI architecture. In this paper, we propose a multi-context graded BDI architecture (called n-BDI) that models norm-autonomous agents able to deal with uncertainty in dynamic environments. The n-BDI architecture has been experimentally evaluated and the results are shown in this paper. © 2014 Elsevier Inc. All rights reserved
The X-ray Luminosities of HH Objects
The recent detection of X-ray emission from HH 2 and HH 154 with the Chandra
and XMM-Newton satellites (respectively) have opened up an interesting, new
observational possibility in the field of Herbig-Haro objects. In order to be
able to plan further X-ray observations of other HH objects, it is now of
interest to be able to estimate their X-ray luminosities in order to choose
which objects to observe. This paper describes a simple, analytic model for
predicting the X-ray luminosity of a bow shock from the parameters of the flow
(i.e., the size of the bow shock, its velocity, and the pre-shock density). The
accuracy of the analytic model is analyzed through a comparison with the
predictions obtained from axisymmetric, gasdynamic simulations of the leading
working surface of an HH jet. We find that our analytic model reproduces the
observed X-ray luminosities of HH 2 and HH 154, and we propose that HH~80/81 is
a good candidate for future observations with Chandra.Comment: 10 pages (8 text, 2 figures
Reasoning about constitutive norms in BDI agents
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Logic Journal of the IGPL following peer review. The definitive publisher-authenticated version: Criado Pacheco, N.; Argente Villaplana, E.; Noriega, P.; Botti Navarro, VJ. (2014). Reasoning about constitutive norms in BDI agents. Logic Journal of the IGPL. 22(1):66-93 is available online at: http://dx.doi.org/1093/jigpal/jzt035Software agents can be members of different institutions along their life; they might even belong to different institutions simultaneously. For these reasons, agents need capabilities that allow them to determine the repercussion that their actions would have within the different institutions. This association between the physical word, in which agents interactions and actions take place, and the institutional world is defined by means of constitutive norms. Currently, the problem of how agents reason about constitutive norms has been tackled from a theoretical perspective only. Thus, there is a lack of more practical proposals that allow the development of software agents capable of reasoning about constitutive norms. In this article we propose an information model, knowledge representation and an inference mechanism to enable Belief-Desire-Intention agents to reason about the consequences of their actions on the institutions and making decisions accordingly. Specifically, the information model, knowledge representation and inference mechanism proposed in this article allows agents to keep track of the institutional state given that they have a physical presence in some real-world environment. Agents have a limited and not fully believable knowledge of the physical world (i.e. they are placed in an uncertain environment). Therefore, our proposal also deals with the uncertainty of the environment.Criado Pacheco, N.; Argente Villaplana, E.; Noriega, P.; Botti Navarro, VJ. (2014). Reasoning about constitutive norms in BDI agents. Logic Journal of the IGPL. 22(1):66-93. doi:10.1093/jigpal/jzt035S6693221Baldi, P., Brunak, S., Chauvin, Y., Andersen, C. A. F., & Nielsen, H. (2000). Assessing the accuracy of prediction algorithms for classification: an overview. Bioinformatics, 16(5), 412-424. doi:10.1093/bioinformatics/16.5.412Bloch, I. (1996). Information combination operators for data fusion: a comparative review with classification. IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans, 26(1), 52-67. doi:10.1109/3468.477860Casali, A., Godo, L., & Sierra, C. (2011). A graded BDI agent model to represent and reason about preferences. Artificial Intelligence, 175(7-8), 1468-1478. doi:10.1016/j.artint.2010.12.006Criado, N., Julián, V., Botti, V., & Argente, E. (2010). A Norm-Based Organization Management System. Lecture Notes in Computer Science, 19-35. doi:10.1007/978-3-642-14962-7_2Governatori, G., & Rotolo, A. (2008). BIO logical agents: Norms, beliefs, intentions in defeasible logic. Autonomous Agents and Multi-Agent Systems, 17(1), 36-69. doi:10.1007/s10458-008-9030-4Grossi, D., Aldewereld, H., Vázquez-Salceda, J., & Dignum, F. (2006). Ontological aspects of the implementation of norms in agent-based electronic institutions. Computational & Mathematical Organization Theory, 12(2-3), 251-275. doi:10.1007/s10588-006-9546-6Hübner, J. F., Boissier, O., Kitio, R., & Ricci, A. (2009). Instrumenting multi-agent organisations with organisational artifacts and agents. Autonomous Agents and Multi-Agent Systems, 20(3), 369-400. doi:10.1007/s10458-009-9084-yJONES, A. J. I., & SERGOT, M. (1996). A Formal Characterisation of Institutionalised Power. Logic Journal of IGPL, 4(3), 427-443. doi:10.1093/jigpal/4.3.427Rawls, J. (1955). Two Concepts of Rules. The Philosophical Review, 64(1), 3. doi:10.2307/2182230Da Silva, V. T. (2008). From the specification to the implementation of norms: an automatic approach to generate rules from norms to govern the behavior of agents. Autonomous Agents and Multi-Agent Systems, 17(1), 113-155. doi:10.1007/s10458-008-9039-
Grain size limits derived from 3.6 {\mu}m and 4.5 {\mu}m coreshine
Recently discovered scattered light from molecular cloud cores in the
wavelength range 3-5 {\mu}m (called "coreshine") seems to indicate the presence
of grains with sizes above 0.5 {\mu}m. We aim to analyze 3.6 and 4.5 {\mu}m
coreshine from molecular cloud cores to probe the largest grains in the size
distribution. We analyzed dedicated deep Cycle 9 Spitzer IRAC observations in
the 3.6 and 4.5 {\mu}m bands for a sample of 10 low-mass cores. We used a new
modeling approach based on a combination of ratios of the two background- and
foreground-subtracted surface brightnesses and observed limits of the optical
depth. The dust grains were modeled as ice-coated silicate and carbonaceous
spheres. We discuss the impact of local radiation fields with a spectral slope
differing from what is seen in the DIRBE allsky maps. For the cores L260,
ecc806, L1262, L1517A, L1512, and L1544, the model reproduces the data with
maximum grain sizes around 0.9, 0.5, 0.65, 1.5, 0.6, and > 1.5 {\mu}m,
respectively. The maximum coreshine intensities of L1506C, L1439, and L1498 in
the individual bands require smaller maximum grain sizes than derived from the
observed distribution of band ratios. Additional isotropic local radiation
fields with a spectral shape differing from the DIRBE map shape do not remove
this discrepancy. In the case of Rho Oph 9, we were unable to reliably
disentangle the coreshine emission from background variations and the strong
local PAH emission. Considering surface brightness ratios in the 3.6 and 4.5
{\mu}m bands across a molecular cloud core is an effective method of
disentangling the complex interplay of structure and opacities when used in
combination with observed limits of the optical depth.Comment: 23 pages, 18 figures, accepted for publication in A&
Modeling and predicting the shape of the far-infrared to submillimeter emission in ultra-compact HII regions and cold clumps
Dust properties are very likely affected by the environment in which dust
grains evolve. For instance, some analyses of cold clumps (7 K- 17 K) indicate
that the aggregation process is favored in dense environments. However,
studying warm (30 K-40 K) dust emission at long wavelength (300
m) has been limited because it is difficult to combine far
infared-to-millimeter (FIR-to-mm) spectral coverage and high angular resolution
for observations of warm dust grains. Using Herschel data from 70 to 500
m, which are part of the Herschel infrared Galactic (Hi-GAL) survey
combined with 1.1 mm data from the Bolocam Galactic Plane Survey (BGPS), we
compared emission in two types of environments: ultra-compact HII (UCHII)
regions, and cold molecular clumps (denoted as cold clumps). With this
comparison we tested dust emission models in the FIR-to-mm domain that
reproduce emission in the diffuse medium, in these two environments (UCHII
regions and cold clumps). We also investigated their ability to predict the
dust emission in our Galaxy. We determined the emission spectra in twelve UCHII
regions and twelve cold clumps, and derived the dust temperature (T) using the
recent two-level system (TLS) model with three sets of parameters and the
so-called T- (temperature-dust emissvity index) phenomenological models,
with set to 1.5, 2 and 2.5. We tested the applicability of the TLS
model in warm regions for the first time. This analysis indicates distinct
trends in the dust emission between cold and warm environments that are visible
through changes in the dust emissivity index. However, with the use of standard
parameters, the TLS model is able to reproduce the spectral behavior observed
in cold and warm regions, from the change of the dust temperature alone,
whereas a T- model requires to be known.Comment: Accepted for publication in A&A. 19 pages, 8 figures, 7 table
Neural Networks for Self-tuning Control Systems
In this paper, we presented a self-tuning control algorithm based on a three layers perceptron type neural network. The proposed algorithm is advantageous in the sense that practically a previous training of the net is not required and some changes in the set-point are generally enough to adjust the learning coefficient. Optionally, it is possible to introduce a self-tuning mechanism of the learning coefficient although by the moment it is not possible to give final conclusions about this possibility. The proposed algorithm has the special feature that the regulation error instead of the net output error is retropropagated for the weighting coefficients modifications.
Acceso a la justicia familiar en la comarca Ngäbe Bublè
This research article has the purpose of reporting on the activities of the Access to Justice and Gender Unit, of the Judicial Branch and the Family Jurisdiction of Panama, which through the Sectional Family Courts of the province of Chiriquí, started a program of access to justice and gender, to bring justice to areas of difficult access, focused on bringing justice closer to the regional sector, providing services in a free, expeditious, timely and participatory manner, in the family jurisdiction, the The program addresses a group of indigenous people who are in conditions of vulnerability, with difficulties and barriers: economic and inclement weather, among others. This research is part of the quantitative methodology, supported by the statistical analyzes provided by the Unit of Access to Justice and Gender. The population under study was the Ngäbe Bugle region, and the period of time was 2019, 2020 and 2022. It is concluded that the objective of the program is achieved and access to justice is given to vulnerable people; 100% effectiveness is shown in achieving care for vulnerable people, this project can be extended to other areas other than the family, it also proved that it can be assumed by other family courts. It is important to continue advancing in the processes of hearings carried out and, in the sentences, handed down.Este artículo de investigación tiene el propósito de informar sobre las actividades de la Unidad de Acceso a la Justicia y Género del Órgano Judicial y la Jurisdicción de Familia de Panamá, el cual a través de los Juzgados Seccionales de Familia de la Provincia de Chiriquí, iniciaron un programa de acceso a la justicia y género, para llevar la justicia hasta las áreas de difícil acceso, enfocados en acercar la justicia al sector comarcal, brindando los servicios en el área de la jurisdicción familiar de manera gratuita, expedita, oportuna y participativa a un grupo de indígenas que se encuentran en condiciones de vulnerabilidad, con dificultades y barreras económicas. Esta investigación, se enmarca en la metodología cuantitativa, apoyada en los análisis estadísticos proporcionados por la Unidad de Acceso a la Justicia y Género. La población objeto de estudio fue la comarca Ngäbe Bugle, y el periodo de tiempo los años 2019, 2020 y 2022. Se concluye que se logra el objetivo del programa y se da acceso a la justicia a personas vulnerables; mostrando una eficacia del 100% en el logro de la atención a personas vulnerables, por lo que el proyecto se puede ampliar a otras áreas distintas a la familiar, asimismo probó que puede ser asumido por otros juzgados de familia. Es importante continuar avanzando en los procesos de audiencias realizadas y en las sentencias dictadas
The jet/counterjet IR symmetry of HH34 and the size of the jet formation region
We present a new Spitzer IRAC images of the HH 34 outflow. These are the
first images that detect both the knots along the southern jet and the northern
counterjet (the counterjet knots were only detected previously in a long slit
spectrum). This result removes the problem of the apparent coexistence of a
large scale symmetry (at distances of up to approx.1 pc) and a complete lack of
symmetry close to the source (at distances of approx. 1.e+17 cm) for this
outflow. We present a quantitative evaluation of the newly found symmetry
between the HH 34 jet and counterjet, and show that the observed degree of
symmetry implies that the jet production region has a characteristic size <2.8
AU. This is the strongest constraint yet derived for the size of the region in
which HH jets are produced.Comment: Accepted for publication, ApJ
Dust properties inside molecular clouds from coreshine modeling and observations
Context. Using observations to deduce dust properties, grain size
distribution, and physical conditions in molecular clouds is a highly
degenerate problem. Aims. The coreshine phenomenon, a scattering process at 3.6
and 4.5 m that dominates absorption, has revealed its ability to explore
the densest parts of clouds. We want to use this effect to constrain the dust
parameters. The goal is to investigate to what extent grain growth (at constant
dust mass) inside molecular clouds is able to explain the coreshine
observations. We aim to find dust models that can explain a sample of Spitzer
coreshine data. We also look at the consistency with near-infrared data we
obtained for a few clouds. Methods. We selected four regions with a very high
occurrence of coreshine cases: Taurus-Perseus, Cepheus, Chameleon and
L183/L134. We built a grid of dust models and investigated the key parameters
to reproduce the general trend of surface bright- nesses and intensity ratios
of both coreshine and near-infrared observations with the help of a 3D
Monte-Carlo radiative transfer code. The grid parameters allow to investigate
the effect of coagulation upon spherical grains up to 5 m in size derived
from the DustEm diffuse interstellar medium grains. Fluffiness (porosity or
fractal degree), ices, and a handful of classical grain size distributions were
also tested. We used the near- and mostly mid-infrared intensity ratios as
strong discriminants between dust models. Results. The determination of the
background field intensity at each wavelength is a key issue. In particular, an
especially strong background field explains why we do not see coreshine in the
Galactic plane at 3.6 and 4.5 m. For starless cores, where detected, the
observed 4.5 m / 3.6 m coreshine intensity ratio is always lower than
0.5 which is also what we find in the models for the Taurus-Perseus and
L183 directions. Embedded sources can lead to higher fluxes (up to four times
greater than the strongest starless core fluxes) and higher coreshine ratios
(from 0.5 to 1.1 in our selected sample). Normal interstellar radiation field
conditions are sufficient to find suitable grain models at all wavelengths for
starless cores. The standard interstellar grains are not able to reproduce
observations and, due to the multi-wavelength approach, only a few grain types
meet the criteria set by the data. Porosity does not affect the flux ratios
while the fractal dimension helps to explain coreshine ratios but does not seem
able to reproduce near-infrared observations without a mix of other grain
types. Conclusions. Combined near- and mid-infrared wavelengths confirm the
potential to reveal the nature and size distribution of dust grains. Careful
assessment of the environmental parameters (interstellar and background fields,
embedded or nearby reddened sources) is required to validate this new
diagnostic
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