Perspective. Theories and experiments on the “veduta vincolata” (restricted sight)

The modern perspective admits the free rotation of the eye situated in the projection centre (restricted sight) and with this, and with the motion of the eye, it is capable of simulating even the impression of curvature of the visual field that Panofsky erroneously ascribes to the curvature of the retina. The restricted sight admits an ample displacement of the observation point along the direction of the normal to the picture plane, whereas it is much less tolerant for a displacement parallel to the picture plane that emphasizes the ‘marginal aberrations’ and not only. This limit has been passed, during the 17th century, by artists like Agostino Tassi through the repetition of the primary point (which is also the vanishing point of the normals to the picture plane). Thus, there are two possible interpretive keys of an architectural perspective: on the one hand the geometrical key, which reveals itself by means of an inverse procedure, capable of describing the shapes that are represented in space; on the other the architectural key, which obtains the same result simply observing the typical characteristics of an architecture, like the symmetry, the horizontality of the architraves, the verticality of the pillars, the proportions of the Order

Jets in neutron star X-ray binaries: a comparison with black holes

(Abridged) We present a comprehensive study of the relation between radio and X-ray emission in neutron star X-ray binaries, use this to infer the general properties of the disc-jet coupling in such systems, and compare the results quantitatively with those already established for black hole systems. There are clear qualitative similarities between the two classes of object: hard states below about 1% of the Eddington luminosity produce steady jets, while transient jets are associated with outbursting and variable sources at the highest luminosities. However, there are important quantitative differences: the neutron stars are less radio-loud for a given X-ray luminosity (regardless of mass corrections), and they do not appear to show the strong suppression of radio emission in steady soft states which we observe in black hole systems. Furthermore, in the hard states the correlation between radio and X-ray luminosities of the neutron star systems is steeper than the relation observed in black holes by about a factor of two. This result strongly suggests that the X-ray emission in the black hole systems is radiatively inefficient, with an approximate relation of the form L_X \propto \dot{m}^2, consistent with both advection-dominated models and jet-dominated scenario. On the contrary the jet power in both classes of object scales linearly with accretion rate. This constitutes some of the first observational evidence for the radiatively inefficient scaling of X-ray luminosity with accretion rate in accreting black hole systems.Comment: Accepted for publication in MNRA

The Black Hole Candidate LSI+61303

In recent years, fundamental relationships for the black hole X-ray binaries have been established between their X-ray luminosity $L_X$ and the photon index $\Gamma$ of their X-ray spectrum. For the moderate-luminosity regime, an anti-correlation between $\Gamma$ and $L_X$ has been observed. In this article, aimed to verify if the moderate luminous X-ray binary system LSI +61303 is a black hole, we analyse $Swift$ observations of LSI +61303. We compare the derived $L_X$ vs $\Gamma$ distribution, first with the statistical trend for black hole X-ray binaries, then with the trend of the pulsar PSR B1259-63, and finally with the individual trends of the black hole X-ray binaries Swift J1357.2-0933 and V404 Cygni. We find that the system PSR B1259-63 shows a positive correlation between $\Gamma$ and $L_X$, whereas in contrast LSI +61303 shows the same anti-correlation as for black hole X-ray binaries. Moreover, the trend of LSI +61303 in the $L_X$/$L_{Eddington} - \Gamma$ plane overlaps with that of the two black holes Swift J1357.2-0933 and V404 Cygni. All three systems, Swift J1357.2-0933, V404 Cygni and LSI +61303 well trace the last part of the evolution of accreting black holes at moderate-luminosity until their drop to quiescence.Comment: 5 pages, 4 figures, MNRAS accepte

Iron Emission Lines from Extended X-ray Jets in SS 433: Reheating of Atomic Nuclei

Powerful relativistic jets are among the most ubiquitous and energetic observational consequences of accretion around supermassive black holes in active galactic nuclei and neutron stars and stellar-mass black holes in x-ray binary (XRB) systems. But despite more than three decades of study, the structure and composition of these jets remain unknown. Here we present spatially resolved x-ray spectroscopy of arc second-scale x-ray jets from the XRB SS 433 analized with the Chandra advanced charge-coupled device imaging spectrometer. These observations reveal evidence for a hot continuum and Doppler-shifted iron emission lines from spatially resolved regions. Apparently, in situ reheating of the baryonic component of the jets takes place in a flow that moves with relativistic bulk velocity even more than 100 days after launch from the binary core

The influence of spin on jet power in neutron star X-ray binaries

We investigate the role of the compact object in the production of jets from neutron star X-ray binaries. The goal is to quantify the effect of the neutron star spin, if any, in powering the jet. We compile all the available measures or estimates of the neutron star spin frequency in jet-detected neutron star X-ray binaries. We use as an estimate of the ranking jet power for each source, the normalisation of the power law which fits the X-ray/radio and X-ray/infrared luminosity correlations L_(radio/IR) proportional to L_(X)^(Gamma) (using infrared data for which there is evidence for jet emission). We find a possible relation between spin frequency and jet power (Spearman rank 97%), when fitting the X-ray/radio luminosity correlation using a power law with slope 1.4; Gamma=1.4 is observed in 4U 1728-34 and is predicted for a radiatively efficient disc and a total jet power proportional to the mass accretion rate. If we use a slope of 0.6, as observed in Aql X-1, no significant relation is found. An indication for a similar positive correlation is also found for accreting millisecond X-ray pulsars (Spearman rank 92%), if we fit the X-ray/infrared luminosity correlation using a power law with slope 1.4. While our use of the normalisation of the luminosity correlations as a measure of the ranking jet power is subject to large uncertainties, no better proxy for the jet power is available. However, we urge caution in over-interpreting the spin-jet power correlations, particularly given the strong dependence of our result on the (highly uncertain) assumed power law index of the luminosity correlations. We discuss the results in the framework of current models for jet formation in black holes and young stellar objects and speculate on possible different jet production mechanisms for neutron stars depending on the accretion mode.Comment: Accepted for publication in MNRA

The negative social function of property in constitutional political systems and the popular affirmation of human rights

Con base en el método de derecho comparado, el presente artículo se detiene en el debate de la función social de la propiedad y en su falta de efectividad en dos realidades constitucionales singulares. Teniendo en consideración el caso de desalojo de Pinheirinho, en la ciudad brasileña de São José dos Campos; y el caso español en Tarragona, Cataluña, sobre las cláusulas abusivas en los contratos de propiedad, materias de derechos humanos parecen delimitar cada vez más el escenario legal en defensa de garantías y principios sociales constitucionales. Distintas constituciones revisadas a lo largo del presente trabajo revelan la idea de función social de la propiedad como una experiencia histórica que no se circunscribe solamente a Brasil y España. Para la superación de la inefectiva aplicabilidad de la categoría jurídica debatida sobre propietarios irresponsables, movimientos sociales y acciones afirmativas populares han hecho un esfuerzo para evitar violaciones de derechos humanos en materia de vivienda, aun cuando sus demandas evocan preguntas del debido procedimiento y derecho del consumidor.According to comparative law method, the present article delves into the social function of property question regarding its ineffectiveness in two different constitutional realities. Taking into consideration the case of eviction, in the Brazilian city of São José dos Campos, area of Pinheirinho; and the Spanish case in Tarragona, Catalonia, about abusive clauses in property contracts, human rights matters are setting the hard law stage for social constitutional principles and guarantees. Different constitutions along the present work emphasise the idea of social function of property as a historical experience not only circumscribed by Spain and Brazil cases. For the ineffectiveness overcoming in the debate about irresponsible proprietors, social movements and popular affirmative actions have made an effort to avoid human rights violations in housing matters, although their demands evoke questions of legal proceeding and consumer protection

The rise and fall of the compact jet in GRO J1655-40

In this work, we present some preliminary results on a multi-wavelength (radio/infrared/optical/X-ray) study of GRO J1655-40 during its 2005 outburst. We focus on the broadband spectral energy distribution during the different stages of the outburst. In particular, using this unprecedented coverage, and especially thanks to the new constraints given in the mid-IR by Spitzer, we can test the physical self-consistent disk-jet model during the hard state, where the source shows radio emission from a compact jet. The hard state broadband spectra of the observations during the decay of the outburst, are fairly well fit using the jet model with parameters overall similar to those found for Cyg X-1 and GX 339-4 in a previous work. However, we find that, compared to the other two BHs, GRO J1655-40 has a much higher jet power (at least a factor of 3), and that, most notably, the model seems to underestimate the radio emissio

From the effectiveness of the right to housing to the right to the city: a three-dimensional rationality for Brazil and Spain

[eng] The conflict between property system and the right to housing has evolved into a more complex inquiry since the beginning of the present research. Our initial analysis on the effectiveness of the social function in ownership discovered in tribunal decisions how restricted was the understanding of property concept. The liberal perception of non-interference in the economy of real estate market reduced the legal debate about the internal limits of property to a financial binary relation, for instance, individuals affected by mortgages and credit institutions, tenants and non-residential landlords, families living in vulnerable socioeconomic conditions and investors. However, the housing problem causes yet a certain legal inquietude since the number of non-occupied properties and the cost of rents are still increasing in Brazil and Spain. Examining the data available for both countries, we found a macroeconomic variable in urban development and housing access intimately linked to stock exchange markets. In addition, the absolute notion of property right is an obstacle inherited from the civil law tradition that impedes the openness of the ownership system to its social dimension. The aim of our thesis is the effective defence of the right to housing as a legal instrument associated with the social function of property and as a connecting factor to other rights in urban context. Our hypothesis requires a three- dimensional rationality for adequate judgments beyond the task of tribunals. A set of reasons of how both societies can limit the transnational real estate speculation, overcome the civil law tradition in an inert tension with democratic sovereignties and use the social function like a legal category so that the effectiveness of the right to housing serves as a turning point for the right to city.[spa] El conflicto entre el sistema de propiedad y el derecho a la vivienda se ha convertido en una investigación más compleja desde el comienzo del presente trabajo. Nuestro análisis inicial sobre la efectividad de la función social de la propiedad identificó en decisiones de tribunales un ejercicio de comprensión muy estricto del concepto de propiedad. La percepción liberal de la no injerencia en la economía del mercado inmobiliario redujo el debate legal sobre los límites internos de la propiedad a una relación binaria financiera, por ejemplo, individuos afectados por hipotecas e instituciones de crédito, inquilinos y propietarios no residenciales, familias que viven en condiciones de vulnerabilidad socioeconómica e inversores. Sin embargo, la vivienda causa todavía cierta inquietud jurídica, ya que el número de propiedades no ocupadas y el costo de los alquileres siguen aumentando en Brasil y España. Examinando los datos disponibles para ambos países, encontramos una variable macroeconómica en el desarrollo urbano y el acceso a la vivienda íntimamente vinculados a los mercados bursátiles. Además, la noción absoluta de derecho de propiedad sigue siendo un obstáculo heredado de la civil law que impide la apertura del sistema de propiedad en su dimensión social. El objetivo de nuestra tesis es contribuir a la defensa efectiva del derecho a la vivienda como instrumento jurídico asociado a la función social de la propiedad y como factor de conexión con otros derechos en el contexto urbano. Nuestra hipótesis requiere una racionalidad tridimensional para juicios adecuados más allá de la tarea de los tribunales. Un conjunto de razones de cómo las dos sociedades pueden limitar la especulación inmobiliaria transnacional, superar la tradición del civil law en tensión inerte con las soberanías democráticas y utilizar la función social como categoría jurídica para que la efectividad del derecho a la vivienda sirva de punto de inflexión para el derecho a la ciudad.[por] O conflito entre o sistema de propriedade e o direito à moradia tornou-se uma indagação mais complexa desde o início da presente pesquisa. Nossa análise inicial sobre a eficácia da função social da propriedade identificou em decisões judiciais um exercício de compreensão muito estreita sobre o conceito de propriedade. A percepção liberal da não interferência na economia do mercado imobiliário reduziu o debate jurídico sobre os limites internos da propriedade para vínculos financeiros binários, por exemplo, pessoas afetadas por inadimplência de suas hipotecas versus instituições de crédito, inquilinos contra propriedades de pessoas jurídicas, famílias em condições de vulnerabilidade socioeconômica contra investidores. No entanto, a habitação ainda causa alguma inquietude legal, já que o número de imóveis desocupados e o custo de aluguéis continuam a aumentar no Brasil e na Espanha. Com base em análise de dados disponíveis para ambas realidades, encontramos uma variável macroeconômica no desenvolvimento urbano e o acesso a moradias intimamente ligados aos mercados de ações. Além disso, a noção absoluta sobre o direito de propriedade continua a ser um obstáculo herdado da tradição do direito civil que impede a abertura do sistema de propriedade a dimensões sociais. O objetivo da nossa tese é contribuir para a defesa efetiva do direito à moradia como instrumento jurídico associado à função social da propriedade e como fator de conexão para outros direitos em contexto urbano. Nossa hipótese requer uma racionalidade tridimensional para julgamentos adequados além da tarefa dos tribunais. Um conjunto de razões sobre como as duas sociedades podem limitar a especulação imobiliária transnacional, superar a tradição do direito civil em tensão inerte com soberanias democráticas e usar a função social como uma categoria legal para que a efetividade do direito à habitação sirva enquanto ponto de inflexão para o direito à cidade

Social Dimensions and Social Function Born in Latin America: Property Limits in the U.S. and the European Union Legal Systems

This article is a comparative analysis of property systems and their social dimensions between the United States (U.S.) and the European Union (EU). Throughout the article, we show how the fees and development taxes applied in the U.S. refer to an ex ante rationale assumed by private owners to compensate communities for land transformation or environmental impacts, while inside the EU, the political consensus is responsible for the imposition of limits in ex post abuses of ownership. Either in public administrations, or in the Council of Ministers of the EU, the social function of property is better understood as a sensitive matter of national governments that may affect the harmony of the organisation (Trstenjak, 2017). First, we point out the importance of the social function of property in historical terms with the intellectual debate introduced by Léon Duguit on the internal limits of ownership. Second, we apply an interpretative methodology to distinguish the meaning, use and totality of law from experience (Ferrajoli, 2008). Third, leading U.S. and EU case laws about disputes involving impact fees, development taxes and the juridical category of social dimension are discussed. Our study concludes that the U.S. legal system is mostly linked to the notion of fees and taxes to tackle abuses in urban development against the environment. The American federalist pact provides public administrations, local, and state courts with robust discretionary power. In contrast, we observed that the EU tends to be more anarchical in mechanisms of enforcement when compared to its institutional legal organisms with supranational binding decisions (Muir, 2015; Wendt, 1992)