On symmetric square values of quadratic polynomials

We prove that there does not exist a non-square quadratic polynomial with integer coefficients and an axis of symmetry which takes square values for N consecutive integers for N=7 or N >= 9. At the opposite, if N <= 6 or N=8 there are infinitely many

Class-Weighted Convolutional Features for Visual Instance Search

Image retrieval in realistic scenarios targets large dynamic datasets of unlabeled images. In these cases, training or fine-tuning a model every time new images are added to the database is neither efficient nor scalable. Convolutional neural networks trained for image classification over large datasets have been proven effective feature extractors for image retrieval. The most successful approaches are based on encoding the activations of convolutional layers, as they convey the image spatial information. In this paper, we go beyond this spatial information and propose a local-aware encoding of convolutional features based on semantic information predicted in the target image. To this end, we obtain the most discriminative regions of an image using Class Activation Maps (CAMs). CAMs are based on the knowledge contained in the network and therefore, our approach, has the additional advantage of not requiring external information. In addition, we use CAMs to generate object proposals during an unsupervised re-ranking stage after a first fast search. Our experiments on two public available datasets for instance retrieval, Oxford5k and Paris6k, demonstrate the competitiveness of our approach outperforming the current state-of-the-art when using off-the-shelf models trained on ImageNet. The source code and model used in this paper are publicly available at http://imatge-upc.github.io/retrieval-2017-cam/.Comment: To appear in the British Machine Vision Conference (BMVC), September 201

A (Nearly) Free Lunch:Extending NAND Flash Lifetime by Exploiting Neglected Physical Properties

NAND flash is a key storage technology in modern computing systems. Without it, many devices would probably not exist today or would at least not benefit from as many features. The very large success of this technology motivated massive efforts to scale it down in order to increase its density further. However, NAND flash is currently facing physical limitations that prevent it reaching smaller cell sizes without severely reducing its storage reliability and lifetime. Accordingly, in the present thesis we aim at relieving some constraints from device manufacturing by addressing flash irregularities at a higher level. For example, we acknowledge the fact that process variation plus other factors render some regions of a flash device more sensitive than others. This difference usually leads to sensitive regions exhausting their lifetime early, which then causes the device to become unusable, while the rest of the device is still healthy, yet not exploitable. Consequently, we propose to postpone this exhaustion point with new strategies that require minimal resources to be implemented and effectively extend flash devices lifetime. Sometimes, our strategies involve unconventional methods to access the flash that are not supported by specification document and, therefore, should not be used lightly. Hence, we also present thorough characterization experiments on actual NAND flash chips to validate these methods and model their effect on a flash device. Finally, we evaluate the performance of our methods by implementing a trace-driven flash device simulator and execute a large set of realistic disk traces. Overall, we exploit properties that are either neglected or not understood to propose methods that are nearly free to implement and systematically extend NAND flash lifetime. We are convinced that future NAND flash architectures will regularly bring radical physical changes, which will inevitably come together with a new set of physical properties to investigate and to exploit

Efectes dels gasos contaminants sobre la salut humana i la biodiversitat en nuclis urbans i morbiditat de l’aparell respiratori causada per l’O3 a Barcelona

La contaminació en els nuclis urbans és un problema que suposa un impacte negatiu tant en la salut dels ciutadans com per a la biodiversitat i medi ambient. Aquest impacte ha de ser previst d’alguna manera per a quantificar els possibles problemes o beneficis que un augment o disminució de la contaminació pot tindre. Barcelona és una ciutat que ha tingut molts episodis de contaminació i en els últims anys ha estat adoptant mesures per combatre-la. El clima de l’àrea urbana de Barcelona, on les temperatures solen ser càlides gran part de l’any, sumat a la contaminació de NOx i COV, fa molt fàcil a la formació d’ozó, gas el qual la literatura ha relacionat amb un gran nombre de problemes respiratoris. En aquest treball, mitjançant les dades del nivell de contaminació de l’O3 i el nombre d’ingressats hospitalaris, es busca quantificar el nombre d’ingressats hospitalaris, els dies de treball perduts i el cost que això suposa per a la sanitat produïda per la morbiditat respiratòria a causa de l’O3 mitjançant un model lineal basat en la literatura ja existent en altres ciutats. Com a resultat, s’ha obtingut que la morbiditat sobre l'aparell respiratori que causada per l'O3 l'any 2019, és de 1712 hospitalitzacions. Els efectes que l'O3 té sobre els dies de treball perduts i el cost monetari que suposa l'hospitalització per problemes respiratoris deguts a l'ozó a Barcelona l’any 2019, és de 3139,101 dies perduts i d’un cost de 4.525.013,69 € respectivament. S’ha trobat que el model lineal és simple i pot servir com a una primera aproximació bàsica. Alhora, s’ha considerat una variació del nivell d’O3 homogeni a tota Barcelona, cosa que fa que el resultat final no sigui del tot precís. També, hi ha molts més matisos que s’haurien de considerar, com la predisposició dels ciutadans a tindre una malaltia respiratòria, o que la morbiditat respiratòria pot ser combinació no tan sols de l’O3, sinó de més gasos contaminants.Pollution in urban areas is a problem that has a negative impact on the health of the inhabitants, the biodiversity and the environment of those urban areas. This impact has to be predicted in some way in order to quantify the possible problems or benefits that an increase or decrease of pollution may have. Barcelona is a city that has had many episodes of air pollution and in recent years has been adopting new measures to fight against it. The climate of Barcelona’s urban area, where the temperatures tend to be warm most part of the year, with the existing NOx and VOC pollution, makes the ozone pollution very easy in that area, a gas which the literature has linked to a large number of respiratory problems. In this project it is intended to quantify the number of hospital admissions, the lost working days and the costs that this supposes for the public healthcare due to the respiratory morbidity caused by O3 using a linear model based on the existing literature in other cities and using the data of O3 pollution and the number of hospital admissions. As a result, it has been obtained that the morbidity on the respiratory system caused by O3 in the year 2019, is 1712 hospitalizations. The effects that O3 has on lost working days and the monetary cost of hospitalization for respiratory problems due to ozone in Barcelona in 2019 is 3139,101 days lost and a cost of 4.525.013,69 €respectively. The linear model has been found to be simple and can serve as a basic first approximation. At the same time, a homogeneous variation of the O3 level throughout Barcelona has been considered, which makes the final result not entirely accurate. Also, there are many more nuances that should be considered, such as the predisposition of citizens to have a respiratory disease, or that respiratory morbidity can be a combination of many pollutant gases and not only O3

Aplicació de catàlegs virtuals per a tablets amb sistema operatiu Android

L'objectiu d'aquest projecte de final de carrera a l'empresa és el de desenvolupar una eina de catàlegs virtuals per a dispositius del tipus "tablet". Es desenvoluparà només la part client (la del tablet) i per el moment només serà compatible amb tablets amb la versió 3 d'Android o superior, tot i que no es descarta que en properes versions s'ampliarà per a que funcioni també en dispositius mòbils amb versions anteriors. La part servidora ja es té a l'empresa. Aquesta eina ha de servir per a que les empreses l'utilitzin com a suport de vendes, de tal manera que es puguin estalviar els costos que suposa la creació i constant renovació d'un catàleg en paper.El objetivo de este proyecto de final de carrera en la empresa es el de desarrollar una herramienta de catálogos virtuales para dispositivos de tipo "tablet". Se desarrollará solo la parte cliente (la del tablet) y por el momento solo será compatible con tablets con la versión 3 de Android o superior, aun así no se descarta que el próximas versiones se ampliará para que funcione también en dispositivos móviles con versiones anteriores. La parte servidora ya se tiene en la empresa. Esta herramienta ha de servir para que las empresas la usen como soporte de ventas, de tal manera que se puedan ahorrar los costes que supone la creación y constante renovación de un catálogo en papel.The goal of this end of degree project at the company is to develop a virtual catalogs tool for tablet devices. Only the client part (the application that will run on tablets) will be developed and actually it will be compatible just with tablet devices running Android 3 or later, but maybe in future versions it will also be compatible with phones running older Android versions. The server part has been already created by the company. This tool must be something that business can use to give sales support, so they can save the costs of creating and constantly updating a paper catalog

Human collagen Krox up-regulates type I collagen expression in normal and scleroderma fibroblasts through interaction with Sp1 and Sp3 transcription factors.

Despite several investigations, the transcriptional mechanisms that regulate the expression of both type I collagen genes (COL1A1 and COL1A2) in either physiological or pathological situations, such as scleroderma, are not completely known. We have investigated the role of hc-Krox transcription factor on type I collagen expression by human dermal fibroblasts. hc-Krox exerted a stimulating effect on type I collagen protein synthesis and enhanced the corresponding mRNA steady-state levels of COL1A1 and COL1A2 in foreskin fibroblasts (FF), adult normal fibroblasts (ANF), and scleroderma fibroblasts (SF). Forced hc-Krox expression was found to up-regulate COL1A1 transcription through a -112/-61-bp sequence in FF, ANF, and SF. Knockdown of hc-Krox by short interfering RNA and decoy strategies confirmed the transactivating effect of hc-Krox and decreased substantially COL1A1 transcription levels in all fibro-blast types. The -112/-61-bp sequence bound specifically hc-Krox but also Sp1 and CBF. Attempts to elucidate the potential interactions between hc-Krox, Sp1, and Sp3 revealed that all of them co-immunoprecipitate from FF cellular extracts when a c-Krox antibody was used and bind to the COL1A1 promoter in chromatin immunoprecipitation assays. Moreover, hc-Krox DNA binding activity to its COL1A1-responsive element is increased in SF, cells producing higher amounts of type I collagen compared with ANF and FF. These data suggest that the regulation of COL1A1 gene transcription in human dermal fibroblasts involves a complex machinery that implicates at least three transcription proteins, hc-Krox, Sp1, and Sp3, which could act in concert to up-regulate COL1A1 transcriptional activity and provide evidence for a pro-fibrotic role of hc-Krox

Suc de taronja: una experiència didàctica d'atenció a la diversitat

Aprofitant la visita de les alumnes del col·legi britànic de la ciutat de Lancaster (GB) al nostre centre va sorgir la idea de fer una experiència interdisciplinar consistent a fer tots els preparatius, des de l'àmbit científic del Projecte de Diversificació Curricular (PDC) de 4t d'ESO, per oferir un gotet de suc de taronja durant tres dies a l'hora del primer esbarj