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The Digital Life of Walkable Streets  [PDF]
Daniele Quercia,Luca Maria Aiello,Rossano Schifanella,Adam Davies
Computer Science , 2015, DOI: 10.1145/2736277.2741631
Abstract: Walkability has many health, environmental, and economic benefits. That is why web and mobile services have been offering ways of computing walkability scores of individual street segments. Those scores are generally computed from survey data and manual counting (of even trees). However, that is costly, owing to the high time, effort, and financial costs. To partly automate the computation of those scores, we explore the possibility of using the social media data of Flickr and Foursquare to automatically identify safe and walkable streets. We find that unsafe streets tend to be photographed during the day, while walkable streets are tagged with walkability-related keywords. These results open up practical opportunities (for, e.g., room booking services, urban route recommenders, and real-estate sites) and have theoretical implications for researchers who might resort to the use social media data to tackle previously unanswered questions in the area of walkability.
Vortex Streets on a Sphere  [PDF]
Ghada Alobaidi,Roland Mallier
Journal of Applied Mathematics , 2011, DOI: 10.1155/2011/712704
Abstract: We consider flows on a spherical surface and use a transformation to transport some well-known periodic two-dimensional vortex streets to that spherical surface to arrive at some new expressions for vortex streets on a sphere. 1. Introduction For fluid flow on a two-dimensional plane, the vorticity at a point is twice the angular rotation. A point vortex is a model of a flow in which the vorticity is zero except at the point itself where the vorticity is infinite, so that there is a nonzero circulation around the point. The study of point vortices on the plane, and other two-dimensional manifolds such as the cylinder, sphere, and torus, has a long history, dating back to the 19th century with Helmholtz [1] initiating the point vortex model and Kirchhoff [2] and Lin [3] formulating it as a Hamiltonian dynamical system. In this paper, we are concerned primarily with vortex streets, which consist of one or more periodic rows of point vortices, the simplest of which is a single infinite row of identical vortices [4]. These have important applications in engineering and geophysics, with a single row having been used to model the quasisteady large-scale vortices arising following the roll-up of a shear layer, and double rows, or von Kármán vortex streets [5], having been used to model the shedding of eddies behind a bluff body. An overview of two-dimensional vortex streets can be found in standard texts on hydrodynamics such as IN [6, 7]. In this paper, we are interested in transporting these well-known vortex streets from the plane to a curved two-dimensional manifold, the surface of a sphere. Flows on a sphere are important because of applications to planetary atmospheres. In his classic monograph, Lamb [6] briefly outlines a method of determining the motion of vortices on a curved manifold and discusses how some of the 19th century work on electrical conduction, such as charge-on-a-sphere problems, by Boltzmann, Kirchhoff, T?pler, and others could be applied to the problem of point vortices on the sphere although Gromeka [8] appears to have been the first to study vortices on a sphere specifically. More recently, the formulation of the motion of vortex streets on curved manifolds has been examined in more detail by Hally [9], with several subsequent studies [10–12] delving more deeply into the formulation of vortex motion on a sphere. A review of some of the work on point vortices on vortices on a sphere can be found in [13]. One interesting thread of research [14–16] has involved using numerical methods, such as contour surgery, to study the motion of
Child work in Bogotá streets
ángela María Pinzón, MD, MPH,Leonardo Brice?o, MD,Ana Isabel Gómez, MD,Catalina Latorre, MD, MPA
Revista Ciencias de la Salud , 2003,
Abstract: Title: Child Labor in the Streets of Bogotá.There are many children working in the streetsof Bogotá. The exact number is unknown andthere is very little information available aboutthis group. Methodology: Descriptive study.Children working in certain streets of Bogotáwere surveyed on Saturday July 19th 2003.Results: A total of 162 children were surveyed,52.5% boys and 47.5% girls; 38.5% youngerthen 5 years and 64.2% older; 61.1% were bythemselves and the rest with an adult; 49.4% werechildren of displaced families and the others werechildren of families from Bogotá. A 33.3% rateof school desertion and a rate of 38.9% lack ofsocial security affiliation were found. The lack ofsocial security affiliation is higher in desplaced families and within this group it is higher in thefamilies that have been living a short period oftime in Bogotá. Discusion: Data suggest a strongrelationship between child labor in the street andthe problem of displaced families; a serious impacton school desertion, and long working hoursexposed to various security, phisical, chemical,ergonomic, and psicosocial risk factors. There arethree groups of children working in the streets ofBogotá: Children of displaced families; childrenthat work in the streets, and children that live inthe streets. Conclusions: Child labor in thestreets of Bogotá is a serious problem, whichrequires attention based on knowledge of causesand the pursuit of effective measures for itseradication.
Multiply-interacting Vortex Streets  [PDF]
Babak G. Oskouei,Eva Kanso,Paul K. Newton
Mathematics , 2010,
Abstract: We investigate the behavior of an infinite array of (reverse) von K'arm'an streets. Our primary motivation is to model the wake dynamics in large fish schools. We ignore the fish and focus on the dynamic interaction of multiple wakes where each wake is modeled as a reverse von K'arm'an street. There exist configurations where the infinite array of vortex streets is in relative equilibrium, that is, the streets move together with the same translational velocity. We examine the topology of the streamline patterns in a frame moving with the same translational velocity as the streets which lends insight into fluid transport through the mid-wake region. Fluid is advected along different paths depending on the distance separating two adjacent streets. Generally, when the distance between the streets is large enough, each street behaves as a single von K'arm'an street and fluid moves globally between two adjacent streets. When the streets get closer to each other, the number of streets that enter into partnership in transporting fluid among themselves increases. This observation motivates a bifurcation analysis which links the distance between streets to the maximum number of streets transporting fluid among themselves. We also show that for short times, the analysis of streamline topologies for the infinite arrays of streets can be expected to set the pattern for the more realistic case of a finite array of truncated streets, which is not in an equilibrium state and its dynamic evolution eventually destroys the exact topological patterns identified in the infinite array case. The problem of fluid transport between adjacent streets may be relevant for understanding the transport of oxygen and nutrients to inner fish in large schools as well as understanding flow barriers to passive locomotion.
Periodic Vortex Streets and Complex Monodromy  [PDF]
Adrian D. Hemery,Alexander P. Veselov
Physics , 2014, DOI: 10.3842/SIGMA.2014.114
Abstract: The explicit constructions of periodic and doubly periodic vortex relative equilibria using the theory of monodromy-free Schr\"odinger operators are described. Several concrete examples with the qualitative analysis of the corresponding travelling vortex streets are given.
Emergency surgery, acute care surgery and the boulevard of broken dreams
Fausto Catena, Ernest E Moore
World Journal of Emergency Surgery , 2009, DOI: 10.1186/1749-7922-4-4
Abstract: The story is always the same; we can call it emergency surgery, acute care surgery, or "Samantha," but the key point is that we do not have a widespread set of minimum standards for emergency surgery.Such standards are just as important as those of ATLS.We need to develop guidelines regarding organizational models to address diseases requiring urgent surgical intervention.This is an integral component in the mission of the World Journal of Emergency Surgery and of the World Society of Emergency Surgery.We must be uniformly prepared all around the world, similar to the uniform emergency protocols for airplanes and airports.If we fail to meet this objective, we will continue to witness preventable complications and deaths affecting both the famous and the non-famous alike.This is a dream, but it needn't be a broken one.In 2010 we will have the 1st World Congress of WSES. If we can successfully develop solid guidelines for surgeons from all around the world we will have accomplished a small yet important "humanitarian mission."These guidelines would be freely available on the WJES web site and surgeons all around the world could reference them.You can call it emergency surgery or acute care surgery, but not the "Boulevard of Broken Dreams".
Le sepolture regie nell’alto medioevo (secoli VI-X) The royal tombs of the High Middle Ages (VI-X Centuries)
Piero Majocchi
Reti Medievali Rivista , 2010, DOI: 10.6092/1593-2214/56
Abstract: Questo repertorio fornisce una breve nota introduttiva sul problema delle tombe regie nell'alto medioevo e una descrizione selettiva delle risorse bibliografiche e informatiche. This review article offers a brief introduction to the issue of royal tombs during the High Middle Ages along with a selective description of bibliographic sources and electronic resources.
The Process of Permanence on the Streets: Street Children in Mexico City
Murrieta,Patricia;
Revista Latinoamericana de Ciencias Sociales, Ni?ez y Juventud , 2010,
Abstract: in this article i use foucault's theory of power to explain children's presence on the streets. i argue that resistance to be subject of family power and to be subject of the power exercised in shelters or governmental institutions is not the only struggle in which participates a child that decides to stay living on the streets. subsistence is difficult; resources are scare. children need power to survive, to protect themselves, to stay. therefore, permanence cannot take place without a minimum amount of power. i find that, when children are on the streets and are given an option, they establish a balance between the street and previous experiences outside the streets. but, not all children have an option or the possibility of exercising that option. my main aim is to understand the reasons why a child stays living on the streets even when she has to face situations as problematic as the situations confronted while living in their home or in a shelter
The Process of Permanence on the Streets. Street Children in Mexico City
Patricia Murrieta
Revista Latinoamericana de Ciencias Sociales, Ni?ez y Juventud , 2010,
Abstract: In this article I use Foucault’s theory of power to explain children’s presence on the streets. I argue that resistance to be subject of family power and to be subject of the power exercised in shelters or governmental institutions is not the only struggle in which participates a child that decides to stay living on the streets. Subsistence is difficult; resources are scare. Children need power to survive, to protect themselves, to stay. Therefore, permanence cannot take place without a minimum amount of power. I find that, when children are on the streets and are given an option, they establish a balance between the street and previous experiences outside the streets. But, not all children have an option or the possibility of exercising that option. My main aim is to understand the reasons why a child stays living on the streets even when she has to face situations as problematic as the situations confronted while living in their home or in a shelter.
Marking Streets to Improve Parking Density  [PDF]
Chao Xu,Steven Skiena
Physics , 2015,
Abstract: Street parking spots for automobiles are a scarce commodity in most urban environments. The heterogeneity of car sizes makes it inefficient to rigidly define fixed-sized spots. Instead, unmarked streets in cities like New York leave placement decisions to individual drivers, who have no direct incentive to maximize street utilization. In this paper, we explore the effectiveness of two different behavioral interventions designed to encourage better parking, namely (1) educational campaigns to encourage parkers to "kiss the bumper" and reduce the distance between themselves and their neighbors, or (2) painting appropriately-spaced markings on the street and urging drivers to "hit the line". Through analysis and simulation, we establish that the greatest densities are achieved when lines are painted to create spots roughly twice the length of average-sized cars. Kiss-the-bumper campaigns are in principle more effective than hit-the-line for equal degrees of compliance, although we believe that the visual cues of painted lines induce better parking behavior.
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