1,789 research outputs found
Access Magazine, March 2016
https://scholarworks.sjsu.edu/accessmagazine/1014/thumbnail.jp
KMOS LENsing Survey (KLENS) : morpho-kinematic analysis of star-forming galaxies at
We present results from the KMOS lensing survey-KLENS which is exploiting
gravitational lensing to study the kinematics of 24 star forming galaxies at
with a median mass of and median
star formation rate (SFR) of . We find that 25% of
these low-mass/low-SFR galaxies are rotation dominated, while the majority of
our sample shows no velocity gradient. When combining our data with other
surveys, we find that the fraction of rotation dominated galaxies increases
with the stellar mass, and decreases for galaxies with a positive offset from
the main sequence. We also investigate the evolution of the intrinsic velocity
dispersion, , as a function of the redshift, , and stellar mass,
, assuming galaxies in quasi-equilibrium (Toomre Q parameter equal
to 1). From the relation, we find that the redshift evolution of
the velocity dispersion is mostly expected for massive galaxies (). We derive a relation, using
the Tully-Fisher relation, which highlights that a different evolution of the
velocity dispersion is expected depending on the stellar mass, with lower
velocity dispersions for lower masses, and an increase for higher masses,
stronger at higher redshift. The observed velocity dispersions from this work
and from comparison samples spanning appear to follow this relation,
except at higher redshift (), where we observe higher velocity dispersions
for low masses () and lower velocity
dispersions for high masses () than
expected. This discrepancy could, for instance, suggest that galaxies at
high- do not satisfy the stability criterion, or that the adopted
parametrisation of the specific star formation rate and molecular properties
fail at high redshift.Comment: Accepted for publication in A&A, 21 pages, 10 figure
Critical Thinking about Urban Studies Linked with Thermodynamic Terms
8th International Scientific Conference on Engineering, Technologies and Systems, TechSys 2019 -- 16 May 2019 through 18 May 2019 -- -- 155190The interaction of urban science with psychology, biology, ecology, and technology creates a rich diversity. Thermodynamics and information theory are among the methods of analysis used to understand urban systems. These methods have a variety of options, and their decision-making processes are complex. Definitions related to the concept of city vary depending on the approach of social science disciplines such as urban science, sociology, geography, economy and public administration. Geographic Information System (GIS) enables the creation of interactive maps of the urban system's transformation processes. Thus, city maps have gained qualifications for the examination of the possible changes and future scenarios. The relationship between city and thermodynamics has been developed with implementations such as energy, sustainability, system approach, spatial analysis, aesthetic evaluation methodologies, urban growth, and urban models. The thermodynamic interpretation of implementations provides concrete data such as heat map of the cities, and energy potential. The interpretation of entropy at the intersection of thermodynamics and information theory gives different perspectives to the concepts such as coding, redefining aesthetics and urban growth. The studies which relates urban issues and entropy concept are very different in approach and content from each other. This situation has also created a ground for meaning shifts. The aim of this study is to critically discuss the methods, concepts, and theories of urban studies related to the thermodynamic terms. As a method, the studies on the approaches of the concepts of thermodynamics in urban planning and urban design will be evaluated with a literature review. © 2019 IOP Publishing Ltd
Fast and Slow Rotators in the Densest Environments: a SWIFT IFS study of the Coma Cluster
We present integral-field spectroscopy of 27 galaxies in the Coma cluster
observed with the Oxford SWIFT spectrograph, exploring the kinematic
morphology-density relationship in a cluster environment richer and denser than
any in the ATLAS3D survey. Our new data enables comparison of the kinematic
morphology relation in three very different clusters (Virgo, Coma and Abell
1689) as well as to the field/group environment. The Coma sample was selected
to match the parent luminosity and ellipticity distributions of the early-type
population within a radius 15' (0.43 Mpc) of the cluster centre, and is limited
to r' = 16 mag (equivalent to M_K = -21.5 mag), sampling one third of that
population. From analysis of the lambda-ellipticity diagram, we find 15+-6% of
early-type galaxies are slow rotators; this is identical to the fraction found
in the field and the average fraction in the Virgo cluster, based on the
ATLAS3D data. It is also identical to the average fraction found recently in
Abell 1689 by D'Eugenio et al.. Thus it appears that the average slow rotator
fraction of early type galaxies remains remarkably constant across many
different environments, spanning five orders of magnitude in galaxy number
density. However, within each cluster the slow rotators are generally found in
regions of higher projected density, possibly as a result of mass segregation
by dynamical friction. These results provide firm constraints on the mechanisms
that produce early-type galaxies: they must maintain a fixed ratio between the
number of fast rotators and slow rotators while also allowing the total
early-type fraction to increase in clusters relative to the field. A complete
survey of Coma, sampling hundreds rather than tens of galaxies, could probe a
more representative volume of Coma and provide significantly stronger
constraints, particularly on how the slow rotator fraction varies at larger
radii.Comment: Accepted for publication in MNRA
Applying reranking strategies to route recommendation using sequence-aware evaluation
Venue recommendation approaches have become particularly useful nowadays due to the increasing number of users registered in location-based social networks (LBSNs), applications where it is possible to share the venues someone has visited and establish connections with other users in the system. Besides, the venue recommendation problem has certain characteristics that differ from traditional recommendation, and it can also benefit from other contextual aspects to not only recommend independent venues, but complete routes or venue sequences of related locations. Hence, in this paper, we investigate the problem of route recommendation under the perspective of generating a sequence of meaningful locations for the users, by analyzing both their personal interests and the intrinsic relationships between the venues. We divide this problem into three stages, proposing general solutions to each case: First, we state a general methodology to derive user routes from LBSNs datasets that can be applied in as many scenarios as possible; second, we define a reranking framework that generate sequences of items from recommendation lists using different techniques; and third, we propose an evaluation metric that captures both accuracy and sequentiality at the same time. We report our experiments on several LBSNs datasets and by means of different recommendation quality metrics and algorithms. As a result, we have found that classical recommender systems are comparable to specifically tailored algorithms for this task, although exploiting the temporal dimension, in general, helps on improving the performance of these techniques; additionally, the proposed reranking strategies show promising results in terms of finding a trade-off between relevance, sequentiality, and distance, essential dimensions in both venue and route recommendation tasksThis work has been funded by the Ministerio de Ciencia, Innovación y Universidades (reference: TIN2016-80630-P) and by the European Social Fund (ESF), within the 2017 call for predoctoral contract
Bayesian inference of population expansions in domestic bovines
The past population dynamics of four domestic and one wild species of bovine were estimated using Bayesian skyline plots, a coalescent Markov chain Monte Carlo method that does not require an assumed parametric model of demographic history. Four domestic species share a recent rapid population expansion not visible in the wild African buffalo (Syncerus caffer). The estimated timings of the expansions are consistent with the archaeological records of domestication
The design dimension of China’s planning system: urban design for development control
This paper investigates the design dimension of China's legal planning framework. It aims to identify the design principles which have been followed in practice, those design elements which have been considered by designers and planners as part of development control, and the extent to which urban design outcomes have been adopted in specific legal plans. It examines 14 urban design cases from Nanjing which were produced in conjunction with the relevant legal plans between 2009 and 2013. The study suggests that in China, urban design has been facing a number of challenges, including limited coverage of design elements, inconsistencies in the design principles followed, an incompatibility between design outcomes and legal plans, and an underestimation of the role of urban design in the delivery process of development control. Nevertheless, recent years have seen a rise in the standard of urban design practice in the country, and an emerging recognition of the role of urban design in local planning policies
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