2,669 research outputs found
Exploring attitudinal factors influencing modal shift:a latent class analysis of Danish commuters
Governments advocate for a modal shift from motorized transport modes to active modes. Various political approaches can be adopted to affect travel behavior and patterns. However, interventions spread across the entire population offer limited opportunities to achieve behavioral change. Furthermore, attitude has been shown to cut across demographic characteristics and strongly influence the conducted travel behavior. Therefore, a latent class analysis including significant sociodemographic variables and value-based attitudes concerning factors influencing transport, settlement, and additional priorities was performed. The study objectively identified five classes of Danish commuters with the same preconditions in terms of commuting distance but with clear differences in attitude and transport modes. Each latent class represents a unique combination of characteristics, which indicates the need to design target group-specific interventions to optimize the chances of influencing travel behavior. In particular, a group of malcontented motorists demonstrating a high intention to change exhibit negative feelings toward car travel and thus appear to act in contravention of their attitudes. In contrast, a class of immovable motorists was found, a class of beneficial commuters and finally two cycling dominated classes of passionate cyclists and environmentalist cyclists. Finally, this study has emphasized that similar attitudes can lead to dissimilar behaviors and that the same behavior can be exhibited for various reasons. We deduced how transport mode choice is influenced by various factors, with habit as one of the strongest, as those with strong habits seem disinclined to information about alternatives and call for âharderâ policy interventions. The findings emphasize the importance of targeted interventions tailored to specific commuter groups to encourage modal shifts towards sustainable transportation.</p
Naupliar and Metanaupliar development of Thysanoessa raschii (Malacostraca, Euphausiacea) from GodthÄbsfjord, Greenland, with a reinstatement of the ancestral status of the free-living Nauplius in Malacostracan evolution
The presence of a characteristic crustacean larval type, the nauplius, in many crustacean taxa has often been considered one of the few uniting characters of the Crustacea. Within Malacostraca, the largest crustacean group, nauplii are only present in two taxa, Euphauciacea (krill) and Decapoda Dendrobranchiata. The presence of nauplii in these two taxa has traditionally been considered a retained primitive characteristic, but free-living nauplii have also been suggested to have reappeared a couple of times from direct developing ancestors during malacostracan evolution. Based on a re-study of Thysanoessa raschii (Euphausiacea) using preserved material collected in Greenland, we readdress this important controversy in crustacean evolution, and, in the process, redescribe the naupliar and metanaupliar development of T. raschii. In contrast to most previous studies of euphausiid development, we recognize three (not two) naupliar (= ortho-naupliar) stages (N1-N3) followed by a metanauplius (MN). While there are many morphological changes between nauplius 1 and 2 (e.g., appearance of long caudal setae), the changes between nauplius 2 and 3 are few but distinct. They involve the size of some caudal spines (largest in N3) and the setation of the antennal endopod (an extra seta in N3). A wider comparison between free-living nauplii of both Malacostraca and non-Malacostraca revealed similarities between nauplii in many taxa both at the general level (e.g., the gradual development and number of appendages) and at the more detailed level (e.g., unclear segmentation of naupliar appendages, caudal setation, presence of frontal filaments). We recognize these similarities as homologies and therefore suggest that free-living nauplii were part of the ancestral malacostracan type of development. The derived morphology (e.g., lack of feeding structures, no fully formed gut, high content of yolk) of both euphausiid and dendrobranchiate nauplii is evidently related to their non-feeding (lecithotrophic) status
Remarks on the entanglement entropy for disconnected regions
Few facts are known about the entanglement entropy for disconnected regions
in quantum field theory. We study here the property of extensivity of the
mutual information, which holds for free massless fermions in two dimensions.
We uncover the structure of the entropy function in the extensive case, and
find an interesting connection with the renormalization group irreversibility.
The solution is a function on space-time regions which complies with all the
known requirements a relativistic entropy function has to satisfy. We show that
the holographic ansatz of Ryu and Takayanagi, the free scalar and Dirac fields
in dimensions greater than two, and the massive free fields in two dimensions
all fail to be exactly extensive, disproving recent conjectures.Comment: 14 pages, 4 figures, some addition
AdS/CFT and Strong Subadditivity of Entanglement Entropy
Recently, a holographic computation of the entanglement entropy in conformal
field theories has been proposed via the AdS/CFT correspondence. One of the
most important properties of the entanglement entropy is known as the strong
subadditivity. This requires that the entanglement entropy should be a concave
function with respect to geometric parameters. It is a non-trivial check on the
proposal to see if this property is indeed satisfied by the entropy computed
holographically. In this paper we examine several examples which are defined by
annuli or cusps, and confirm the strong subadditivity via direct calculations.
Furthermore, we conjecture that Wilson loop correlators in strongly coupled
gauge theories satisfy the same relation. We also discuss the relation between
the holographic entanglement entropy and the Bousso bound.Comment: 29 pages, harvmac, 7 figures, references adde
Scale Free Cluster Distributions from Conserving Merging-Fragmentation Processes
We propose a dynamical scheme for the combined processes of fragmentation and
merging as a model system for cluster dynamics in nature and society displaying
scale invariant properties. The clusters merge and fragment with rates
proportional to their sizes, conserving the total mass. The total number of
clusters grows continuously but the full time-dependent distribution can be
rescaled over at least 15 decades onto a universal curve which we derive
analytically. This curve includes a scale free solution with a scaling exponent
of -3/2 for the cluster sizes.Comment: 4 pages, 3 figure
Diffusion, Fragmentation and Coagulation Processes: Analytical and Numerical Results
We formulate dynamical rate equations for physical processes driven by a
combination of diffusive growth, size fragmentation and fragment coagulation.
Initially, we consider processes where coagulation is absent. In this case we
solve the rate equation exactly leading to size distributions of Bessel type
which fall off as for large -values. Moreover, we provide
explicit formulas for the expansion coefficients in terms of Airy functions.
Introducing the coagulation term, the full non-linear model is mapped exactly
onto a Riccati equation that enables us to derive various asymptotic solutions
for the distribution function. In particular, we find a standard exponential
decay, , for large , and observe a crossover from the Bessel
function for intermediate values of . These findings are checked by
numerical simulations and we find perfect agreement between the theoretical
predictions and numerical results.Comment: (28 pages, 6 figures, v2+v3 minor corrections
The Savvidy ``ferromagnetic vacuum'' in three-dimensional lattice gauge theory
The vacuum effective potential of three-dimensional SU(2) lattice gauge
theory in an applied color-magnetic field is computed over a wide range of
field strengths. The background field is induced by an external current, as in
continuum field theory. Scaling and finite volume effects are analyzed
systematically. The first evidence from lattice simulations is obtained of the
existence of a nontrivial minimum in the effective potential. This supports a
``ferromagnetic'' picture of gluon condensation, proposed by Savvidy on the
basis of a one-loop calculation in (3+1)-dimensional QCD.Comment: 9pp (REVTEX manuscript). Postscript figures appende
Picturing protest: visuality, visibility and the public sphere (special issue introduction).
Aims and Scope: This special issue is concerned with how and why certain visual images picturing protest events
and social movements are rendered visible or invisible in the public sphere. âPicturing Protestâ
responds to the growing interest in a new protest culture and new ways of âdoing politicsâ,
ranging from Arab revolts to the Occupy Movement, the Indignados and anti-austerity protests
in Europe. Since 2011 these new activisms have gained momentum in media and scholarly
debates. Contemporary activisms are seen as powerfully tied in to the possibilities that social
media platforms and web 2.0 technologies offer to those involved in practices of dissent in
physical squares and streets as much as in virtual environments. Of special interest here is how
new forms of political participation and the practice of dissent go in tandem with the
widespread use of visual images and internet memes facilitated by technological devices with
documentation facilities (e.g., smartphones, tablets) and social network technologies (Bennett
and Segerberg 2012). Iconic images like the image of dying Neda, a 26-year-old Iranian woman
killed by a sniper bullet during a protest event, go viral in social media platforms and have the
power to galvanize the attention of global publics. Hence, this new protest culture demands for
a different approach in the study of how protest images are constituted, analysed, interpreted
and circulated in both old and new media environments.
Taken all together, the different contributions ask how and why activists, photojournalists,
citizen journalists and journalists use protest images, ranging from maps, posters, to amateur
and professional photographs, to communicate with a range of audiences within and beyond
nationally-defined public spheres. The contributors do so by employing theoretical tools and
methods that originate from within a variety of disciplines, including media and communication, political science, sociology, semiotics and art history. In pursuing their research, the contributors draw on a variety of political contexts, including Spain, Portugal, the
West Bank and the Gaza Strip, Greece, Germany, Italy, Austria and the UK. One of the key
aims of this special issue is to overcome the overemphasis on the intended symbolic meanings
of protest images (Philipps, 2011), by directing the analytical lens to issues of image production
and diffusion. It does so to show how certain visual images, and not others, end up circulating
in a range of traditional and new media environments
Transport coefficients for electrolytes in arbitrarily shaped nano and micro-fluidic channels
We consider laminar flow of incompressible electrolytes in long, straight
channels driven by pressure and electro-osmosis. We use a Hilbert space
eigenfunction expansion to address the general problem of an arbitrary cross
section and obtain general results in linear-response theory for the hydraulic
and electrical transport coefficients which satisfy Onsager relations. In the
limit of non-overlapping Debye layers the transport coefficients are simply
expressed in terms of parameters of the electrolyte as well as the geometrical
correction factor for the Hagen-Poiseuille part of the problem. In particular,
we consider the limits of thin non-overlapping as well as strongly overlapping
Debye layers, respectively, and calculate the corrections to the hydraulic
resistance due to electro-hydrodynamic interactions.Comment: 13 pages including 4 figures and 1 table. Typos corrected. Accepted
for NJ
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