A note on the Petri loci

Let \M_g be the course moduli space of complex projective nonsingular curves of genus $g$. We prove that when the Brill-Noether number $\rho(g,r,n)$ is non-negative every component of the Petri locus P^r_{g,n}\subset \M_g whose general member is a curve $C$ such that $W^{r+1}_n(C) = \emptyset$, has codimension one in \M_g.Comment: Final version, to appear on Manuscripta Mathematic

Dating the Italian Business Cycle: A Comparison of Procedures

The problem of dating the business cycle has recently received many contributions, with a lot of proposed statistical methodologies, parametric and non parametric. Despite of this, only a few countries produce an official dating of the business cycle. In this work we try to apply some procedures for an automatic dating of the Italian business cycle in the last thirty years, checking differences among various methodologies and with the ISAE chronology. To this end parametric as well as non parametric methods are employed. The analysis is carried out both aggregating results from single time series and directly in a multivariate framework. The different methods are also evaluated with respect to their ability to timely track turning points. KEYWORDS: signal extraction, turning points, parametric methods, nonparametric methodssignal extraction, turning points, parametric methods, nonparametric methods

Mukai's program for curves on a K3 surface

Let C be a general element in the locus of curves in M_g lying on some K3 surface, where g is congruent to 3 mod 4 and greater than or equal to 15. Following Mukai's ideas, we show how to reconstruct the K3 surface as a Fourier-Mukai transform of a Brill-Noether locus of rank two vector bundles on C.Comment: Final version. To appear in "Algebraic Geometry

Bruno, E. “Memory and regeneration through segregation: the heritage preservation in Lijiao Village in the City”. In: Pedata, L., Profido, E., Rossi, L., (eds.) [Co]habitation tactics: imagining future spaces in architecture, city and landscape: Tirana architecture week (TAW): international Scientific Conference: Tirana, 20th-23rd September 2018. Polis Press, 2018: 371-380.

Villages in the city (VICs) have become a crucial topic within Chinese urban studies, spatially exposing the contradictions between fast urbanization processes and former rural communities. Beside the social implications of these areas encapsulated in metropolitan cityscapes, their redevelopment into future gated residential communities poses a series of questions about local socio-spatial practices put in transition. For instance their overcrowded built environment, absorbing historical stratifications, is under extreme pressures facing “pro-growth” municipal urban planning visions. Lijiao village represents in Guangzhou a crucial case study to illustrate how local listed cultural heritage could confront tested tabula rasa approaches, redefining the processes embedded in these kind of regeneration projects. The paper aims to demonstrates how the presence of historical relics, permitted the activation of a series of processes diverging from the neoliberal strategies applied by Chinese urban planning bureaucracy, questioning alternative methodologies which had to re-scale actions and cooperate with local consistency. On one side the creation of lists of buildings under preservation activated the compact intervention of institutions and experts, determining rules affecting the negotiation through legitimated procedures. On the other the intervention of the private investor, seeking an efficient quantity distribution over the demolished village, perceived local memory a tangible obstacle opposing the development. Their contraposition promoted formalized spatial boundaries instead of integrating differences. Segregating cultural heritage from its local morphology, cleaning up history, therefore appears as the spatial compromise to safeguard relics elsewhere forcibly demolished or indifferently relocated. Preservation tactics and new urban development, stays one next to the other without considering the collective memory built over centuries of local practices. The spatial codification to promote development, seems the only way to surpass the contradictions of thirty years of fast urban development

Community, real estate pressure and the spatial reorganization: the case study of the “village in the city” of Lijiao in Guangzhou

The paper wants to explore the relationship between the community of Lijiao “village in the city”, located in Haizhu District of Guangzhou, and the promoters of its redevelopment. The literature around the topic of the “villages in the city” has strongly emerged in the last 10 years, due to many case studies of relocations inside the urban expansion of the Pearl River Delta Metropolis. A combination of field of interests like social inequalities, rural-urban migrations, urban planning in a transforming spatial economy and strong administrative bureaucracy, find their combination in a specific site with a long history of land settlement and social practices. The case study of Lijiao village it’s crucial in order to understand the equilibriums between the local community administration system and the top-down and rhetorical visions of the urban planning. In fact the strong volunteer promote by the Local Government to continue the North-South axis of the Central Business District of Guangzhou, will effect in the future this location suspended between the peri-urban interface and an expanding central core. Because the transformation is not yet occurred, the research wants to map these spatial struggles between the parties now disposed around an unstable negotiations, rhetorical participation processes and media consensus

Reaching the sea: Guangzhou southern expansion from rural industrialization to polarized strategical planning

At the turning point of the new century Chinese urban growth has arrived to a new challenge: the improvement of its urban space after the astonishing development of the late Eighties and Nineties. At that time many scholars, impressed by the great urban sprawl occurring in China and other Asian regions, tried to conceptualize models in order to explain that particular phenomenon of the peri-urban dispersion. The paper wants to explore, selecting the city of Guangzhou as case study, capitol of Guangdong Province, which are the most influential passages that could demonstrate how much policy has influenced the management of the urban spatial growth. Analysing a system of driving forces, derived from the market but managed by the political system, and comparing them with the mapping of the city growth in a temporal dynamic selection, it’s possible to understand that South China cities had to change their planning from agglomeration to strategical organization in order to survive. In this way Guangzhou has achieved the possibility to redefine its leading role inside the Pearl River Metropolis, improving urban space from dispersion to a multi-polar and specialized system

Saliency Map for Visual Perception

Human and other primates move their eyes to select visual information from the scene, psycho-visual experiments (Constantinidis, 2005) suggest that attention is directed to visually salient locations in the image. This allows human beings to bring the fovea onto the relevant parts of the image, to interpret complex scenes in real time. In visual perception, an important result was the discovery of a limited set of visual properties (called pre attentive), detected in the first 200-300 milliseconds of observation of a scene, by the low-level visual system. In last decades many progresses have been made into research of visual perception by analyzing both bottom up (stimulus driven) and top down (task dependent) processes involved in human attention. Visual Saliency deals with identifying fixation points that a human viewer would focus on the first seconds of the observation of a scene

Image Quality Assessment by Saliency Maps

Image Quality Assessment (IQA) is an interesting challenge for image processing applications. The goal of IQA is to replace human judgement of perceived image quality with a machine evaluation. A large number of methods have been proposed to evaluate the quality of an image which may be corrupted by noise, distorted during acquisition, transmission, compression, etc. Many methods, in some cases, do not agree with human judgment because they are not correlated with human visual perception. In the last years the most modern IQA models and metrics considered visual saliency as a fundamental issue. The aim of visual saliency is to produce a saliency map that replicates the human visual system (HVS) behaviour in visual attention process. In this paper we show the relationship between different kind of visual saliency maps and IQA measures. We particularly perform a lot of comparisons between Saliency-Based IQA Measures and traditional Objective IQA Measure. In Saliency scientific literature there are many different approaches for saliency maps, we want to investigate which is best one for IQA metrics

Dissecting the FEAST algorithm for generalized eigenproblems

We analyze the FEAST method for computing selected eigenvalues and eigenvectors of large sparse matrix pencils. After establishing the close connection between FEAST and the well-known Rayleigh-Ritz method, we identify several critical issues that influence convergence and accuracy of the solver: the choice of the starting vector space, the stopping criterion, how the inner linear systems impact the quality of the solution, and the use of FEAST for computing eigenpairs from multiple intervals. We complement the study with numerical examples, and hint at possible improvements to overcome the existing problems.Comment: 11 Pages, 5 Figures. Submitted to Journal of Computational and Applied Mathematic