Riesgos jurídicos y responsabilidad en el ámbito del Machine Learning aplicado a las redes sociales

El presente trabajo tiene como objetivo plantear un estudio sobre la inteligencia artificial en relación con las redes sociales y los principales riesgos derivados de su interacción desde un punto de vista jurídico, centrándonos para ello en el concepto del metaverso. En este sentido, estudiaremos la automatización de los avatares que interactúan en el metaverso, se permite crear interacciones autónomas que se puede llevar a cabo en el mundo virtual mediante la inteligencia artificial, lo que produce un gran número de efectos e implicaciones. Además se expondrán los posibles riesgos y sus consecuencias, se realizará después un estudio en torno a la regulación existente y las nuevas propuestas que están surgiendo. Posteriormente se entrará a valorar el marco de la responsabilidad civil y de sus posibles regímenes de atribución derivado de los daños consecuencia de los riesgos mencionados.The aim of this paper is to study artificial intelligence in relation to social networks and the main risks derived from their interaction from a legal point of view, focusing on the concept of the metaverse. In this sense, we will study the automation of avatars that interact in the metaverse, allowing the creation of autonomous interactions that can be carried out in the virtual world by means of artificial intelligence, which produces a large number of effects and implications. In addition, the possible risks and their consequences will be presented, followed by a study of existing regulation and new proposals that are emerging. Subsequently, the framework of civil liability and the possible attribution regimes arising from the damage resulting from the above-mentioned risks will be assessed.Máster Universitario en Acceso a la Profesión de Abogado (M155

Buscas domiciliárias após detenções em flagrante delito: O limite e a extensão do mandato conferido ao OPC

Após a realização de detenções em flagrante delito, mediante o respeito de certos requisitos legais, os órgãos de polícia criminal (OPC) poderão proceder a buscas domiciliárias subsequentes. No entanto, ainda que se trate de um instituto relativamente bem densificado, quer na Constituição da República Portuguesa (CRP), quer no Código de Processo Penal (CPP), existem determinadas lacunas que causam dúvidas acerca do procedimento a adotar, nomeadamente a definição do tempo em que medeia entre a detenção e a execução da busca domiciliária. Assim, inexistindo um prazo previsto na letra da lei, levantam-se, desde logo, dúvidas no que concerne ao limite e à extensão do mandato conferido ao OPC no âmbito desta matéria, acrescendo o facto da existência de decisões judiciais que legitimam buscas domiciliárias subsequentes a detenções em flagrante delito, que se realizaram três horas após a detenção; e outras, que não legitimaram tal diligência volvidos trinta minutos após a detenção. Neste sentido, ao se interpretar os preceitos que preconizam os requisitos necessários para a realização de tal diligência – o artigo 34.º da CRP e os artigos 174.º e 177.º do CPP –, verifica-se que não existe a previsão de qualquer prazo estabelecido na lei. E também, considerando os requisitos plasmados na CRP e no CPP, sem mais, verificar-se-á, numa primeira abordagem, que nada obsta a que se façam buscas domiciliárias após detenções em flagrante delito de crimes como os de condução sob o efeito de álcool e a condução sem habilitação legal, porém, analisando a questão, verifica-se que tal diligência não é admissível. Suportando-se da utilização do Direito, através da recolha normativa, jurisprudencial e doutrinária, esta investigação escalpelizou esse tipo de problemáticas, logrando torná-las inteligíveis e elucidativas, o que poderá consubstanciar uma mais-valia para os operadores judiciários, a quem incumbe a aplicação do direito aos casos concretos.After arrests in flagrante delicto, if certain legal requirements are met, the police may carry out subsequent house searches. However, although it is a relatively well-detailed institute, both in the Constitution of the Portuguese Republic (CRP) and in the Criminal Procedure Code (CPP), there are certain gaps that cause doubts about the procedure to be adopted, namely the definition of the time between the arrest and the execution of the home search. As there is no time limit laid down in the letter of the law, doubts are raised as to the limit and extent of the mandate given to the police in this area. There are also judicial decisions that legitimize home searches following arrests in the act of committing an offence, which are carried out three hours after the arrest, and others that do not legitimize such a search more than thirty minutes after the arrest. In this sense, when interpreting the precepts that establish the necessary requirements for the realization of such diligence – Article 34 of the CRP and Articles 174 and 177 of the CPP – it appears that there is no provision for any deadline established by law. And, considering the requirements set out in the CRP and the CPP, without further ado, it will be verified, in a first approach, that there is nothing to prevent house searches after arrests in the act of committing an offence of crimes such as driving under the influence of alcohol and driving without a legal license, however, analysing the issue it is verified that such diligence is not admissible. Supported by the use of Law, through normative, jurisprudential and doctrinaire collection, this research examined this type of problems, managing to make them intelligible and elucidative, which may consubstantiate an added value for judicial operators, who are responsible for the application of law to concrete cases

Superconductivity and Spin Fluctuations in the Electron-Doped Infinitely-Layered High Tc Superconductor Sr0.9_0.9La0.1_0.1CuO2_2 (Tc=42K)

This paper describes the first 63-Cu NMR study of an electron-doped infinitely-layered high Tc superconductor Sr$_0.9$La$_0.1$CuO$_2$ (Tc=42K). The spin dynamics in the normal state above Tc exhibits qualitatively the same behavior as some hole-doped materials with significantly enhanced spin fluctuations. Below Tc, we observed no signature of a Hebel-Slichter coherence peak, suggesting an unconventional nature of the symmetry of the superconducting order parameter.Comment: Invited Paper to SNS-95 Conference (Spectroscopies on Novel Superconductors 1995 at Stanford). Also presented at Aspen Winter Conference on Superconductivity and Grenoble M^2S-HTSC in 199

Resonant two-magnon Raman scattering in antiferromagnetic insulators

We propose a theory of two-magnon {\it resonant\/} Raman scattering from antiferromagnetic insulators, which contains information both on the magnetism and the carrier properties in the lighly doped phases. We argue that the conventional theory does not work in the resonant regime, in which the energy of the incident photon is close to the gap between the conduction and valence bands. We identify the diagram which gives the dominant contribution to Raman intensity in this regime and show that it can explain the unusual features in the two-magnon profile and in the two-magnon peak intensity dependence on the incoming photon frequency.Comment: 11 pages (REVTeX) + 3 figures in a single postscript file are appended in uuencoded format, preprint TCSUH-94:09

Theory of a Higher Order Phase Transition: Superconducting Transition in BKBO

We describe here the properties expected of a higher (with emphasis on the order fourth) order phase transition. The order is identified in the sense first noted by Ehrenfest, namely in terms of the temperature dependence of the ordered state free energy near the phase boundary. We have derived an equation for the phase boundary in terms of the discontinuities in thermodynamic observables, developed a Ginzburg-Landau free energy and studied the thermodynamic and magnetic properties. We also discuss the current status of experiments on $Ba_{0.6}K_{0.4}BiO_3$ and other $BiO_3$ based superconductors, the expectations for parameters and examine alternative explanations of the experimental results.Comment: 18 pages, no figure

Superexchange coupling and spin susceptibility spectral weight in undoped monolayer cuprates

A systematic inelastic neutron scattering study of the superexchange interaction in three different undoped monolayer cuprates (La_2CuO_4, Nd_2CuO_4 and Pr_2CuO_4) has been performed using conventional triple axis technique. We deduce the in-plane antiferromagnetic (AF) superexchange coupling $J$ which actually presents no simple relation versus crystallographic parameters. The absolute spectral weight of the spin susceptibility has been obtained and it is found to be smaller than expected even when quantum corrections of the AF ground state are taken into account.Comment: 13 pages, 1 table, 3 figure

Quasiparticle excitation in and around the vortex core of underdoped YBa_2Cu_4O_8 studied by site-selective NMR

We report a site-selective ^{17}O spin-lattice relaxation rate T_1^{-1} in the vortex state of underdoped YBa_2Cu_4O_8. We found that T_1^{-1} at the planar sites exhibits an unusual nonmonotonic NMR frequency dependence. In the region well outside the vortex core, T_1^{-1} cannot be simply explained by the density of states of the Doppler-shifted quasiparticles in the d-wave superconductor. Based on T_1^{-1} in the vortex core region, we establish strong evidence that the local density of states within the vortex core is strongly reduced.Comment: 5 pages, 3 figure

Universal Static and Dynamic Properties of the Structural Transition in Pb(Zn1/3Nb2/3)O3

The relaxors Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_{3}$ (PZN) and Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ (PMN) have very similar properties based on the dielectric response around the critical temperature $T_{c}$ (defined by the structural transition under the application of an electric field). It has been widely believed that these materials are quite different below $T_{c}$ with the unit cell of PMN remaining cubic while in PZN the low temperature unit cell is rhombohedral in shape. However, this has been clarified by recent high-energy x-ray studies which have shown that PZN is rhombohedral only in the skin while the shape of the unit cell in the bulk is nearly cubic. In this study we have performed both neutron elastic and inelastic scattering to show that the temperature dependence of both the diffuse and phonon scattering in PZN and PMN is very similar. Both compounds show a nearly identical recovery of the soft optic mode and a broadening of the acoustic mode below $T_{c}$. The diffuse scattering in PZN is suggestive of an onset at the high temperature Burns temperature similar to that in PMN. In contrast to PMN, we observe a broadening of the Bragg peaks in both the longitudinal and transverse directions below $T_{c}$. We reconcile this additional broadening, not observed in PMN, in terms of structural inhomogeneity in PZN. Based on the strong similarities between PMN and PZN, we suggest that both materials belong to the same universality class and discuss the relaxor transition in terms of the three-dimensional Heisenberg model with cubic anisotropy in a random field.Comment: 11 pages, 10 figures. Updated version after helpful referee comment

Comparison of the Electronic Structures and Energetics of Ferroelectric LiNbO3 and LiTaO3

This paper explains the origin of the ferroelectric instability in LiNbO3 and LiTaO3 and compares the electronic structures and energetics of the two materials.Comment: 31 pages, 11 Postscript figure

Resonant Raman Scattering in Antiferromagnets

Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-$T_c$ materials. Recent experiments have shown a strong dependence of the Raman signal in $B_{1g}$ geometry on the frequency of the incoming photon. We present an analytical and numerical study of the Raman intensity in the resonant regime. It has been previously argued by one of us (A.Ch) and D. Frenkel that the most relevant contribution to the Raman vertex at resonance is given by the triple resonance diagram. We derive an expression for the Raman intensity in which we simultaneously include the enhancement due to the triple resonance and a final state interaction. We compute the two-magnon peak height (TMPH) as a function of incident frequency and find two maxima at $\omega^{(1)}_{res} \approx 2\Delta + 3J$ and $\omega^{(2)}_{res} \approx 2\Delta + 8J$. We argue that the high-frequency maximum is cut only by a quasiparticle damping, while the low-frequency maximum has a finite amplitude even in the absence of damping. We also obtain an evolution of the Raman profile from an asymmetric form around $\omega^{(1)}_{res}$ to a symmetric form around $\omega^{(2)}_{res}$. We further show that the TMPH depends on the fermionic quasiparticle damping, the next-nearest neighbor hopping term $t^{\prime}$ and the corrections to the interaction vertex between light and the fermionic current. We discuss our results in the context of recent experiments by Blumberg et al. on $Sr_2CuO_2Cl_2$ and $YBa_2Cu_3O_{6.1}$ and R\"{u}bhausen et al. on $PrBa_2Cu_3O_7$ and show that the triple resonance theory yields a qualitative and to some extent also quantitative understanding of the experimental data.Comment: 19 pages, RevTeX, 16 figures embedded in the text, ps-file is also available at http://lifshitz.physics.wisc.edu/www/morr/morr_homepage.htm