Lieb-Robinson Bounds for Spin-Boson Lattice Models and Trapped Ions

We derive a Lieb-Robinson bound for the propagation of spin correlations in a model of spins interacting through a bosonic lattice field, which satisfies a Lieb-Robinson bound in the absence of spin-boson couplings. We apply these bounds to a system of trapped ions and find that the propagation of spin correlations, as mediated by the phonons of the ion crystal, can be faster than the regimes currently explored in experiments. We propose a scheme to test the bounds by measuring retarded correlation functions via the crystal fluorescence

Confidential database-as-a-service approaches: taxonomy and survey

Outsourcing data to external providers has gained momentum with the advent of cloud computing. Encryption allows data confidentiality to be preserved when outsourcing data to untrusted external providers that may be compromised by attackers. However, encryption has to be applied in a way that still allows the external provider to evaluate queries received from the client. Even though confidential database-as-a-service (DaaS) is still an active field of research, various techniques already address this problem, which we call confidentiality preserving indexing approaches (CPIs). CPIs make individual tradeoffs between the functionality provided, i.e., the types of queries that can be evaluated, the level of protection achieved, and performance.In this paper, we present a taxonomy of requirements that CPIs have to satisfy in deployment scenarios including the required functionality and the required level of protection against various attackers. We show that the taxonomy?s underlying principles serve as a methodology to assess CPIs, primarily by linking attacker models to CPI security properties. By use of this methodology, we survey and assess ten previously proposed CPIs. The resulting CPI catalog can help the reader who would like to build DaaS solutions to facilitate DaaS design decisions while the proposed taxonomy and methodology can also be applied to assess upcoming CPI approaches

Modelación y análisis no lineal de muros estructurales de hormigón armado

The severe damage and collapse of many reinforced concrete (RC) wall buildings observed in recent earthquakes in Chile (2010) and New Zealand (2011) showed that RC walls did not perform as required by the building codes of both countries. In this context, it is necessary to intensify the research efforts towards more precise simulations of damage indicators, particularly of local engineering demand parameters, such as material strains, which are fundamental for the application of the Performance-Based Earthquake Engineering (PBEE) methodology. The main goal of this study is to propose an analytical nonlinear model capable of simulating the response of isolated reinforced concrete walls at a global and local level. This work compared different response parameters obtained from nonlinear analysis of RC walls subjected to cyclic loads, using finite element models developed with DIANA software. The modeling approach was validated with experimental data from two RC walls. A sensitivity analysis of the seismic response parameters to uncertain modeling variables such as the compressive fracture energy of unconfined and confined concrete, among others, was also performed. The analytical models adequately captured the lateral force-displacement relationship, stiffness degradation, and the profile of vertical strains at the base of the walls for different levels of demand. The sensitivity analysis showed that the dispersion of the local response is greater than the dispersion in the global response when considering different modeling parameters. Dispersion increases as the level of demand increases. Manuscript received: October 7, 2021Manuscript accepted: November 18, 2021El daño severo y el colapso de edificios de muros de hormigón armado (HA) observado en terremotos recientes en Chile (2010) y Nueva Zelanda (2011) mostraron que los muros de HA no se desempeñaron acorde a la exigencia de los códigos de ambos países.  En este contexto es necesario intensificar los esfuerzos de investigación hacia simulaciones más precisas de los indicadores de daños, particularmente de los parámetros de demanda ingenieril local, como deformaciones del material, que son fundamentales para la aplicación del método de ingeniería sísmica basada en desempeño. El objetivo principal de este estudio es proponer un modelo analítico no lineal capaz de simular la respuesta de muros aislados de hormigón armado a nivel global y local. Este trabajo comparó diferentes parámetros de respuesta obtenidos del análisis no lineal de muros de HA sometidos a cargas cíclicas, mediante modelos de elementos finitos desarrollados en el programa DIANA. El enfoque de modelado se validó con datos experimentales de dos muros de HA. Se realizó también un análisis de sensibilidad de los parámetros de respuesta sísmica a las variables de modelado inciertas como la energía de fractura en compresión del hormigón no confinado y confinado, entre otras. Los modelos analíticos capturaron adecuadamente la relación fuerza lateral-desplazamiento, la degradación de la rigidez y el perfil de deformaciones verticales en la base de los muros para diferentes niveles de demanda. El análisis de sensibilidad indicó que la dispersión de la respuesta local es mayor que la dispersión en la respuesta global, al considerar diferentes parámetros de modelado. La dispersión aumenta a medida que aumenta el nivel de demanda. Artículo recibido: 7 de octubre de 2021 Artículo aceptado: 18 de noviembre de 202

The Interspersed Spin Boson Lattice Model

We describe a family of lattice models that support a new class of quantum magnetism characterized by correlated spin and bosonic ordering [Phys. Rev. Lett. 112, 180405 (2014)]. We explore the full phase diagram of the model using Matrix-Product-State methods. Guided by these numerical results, we describe a modified variational ansatz to improve our analytic description of the groundstate at low boson frequencies. Additionally, we introduce an experimental protocol capable of inferring the low-energy excitations of the system by means of Fano scattering spectroscopy. Finally, we discuss the implementation and characterization of this model with current circuit-QED technology.Comment: Submitted to EPJ ST issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases

The sensitivity and specificity of a diagnostic test of sequence-space synesthesia

People with sequence-space synaesthesia (SSS) report stable visuo-spatial forms corresponding to numbers, days and months (amongst others). This type of synaesthesia has intrigued scientists for over 130 years but the lack of an agreed upon tool for assessing it has held back research on this phenomenon. The present study builds on previous tests by measuring the consistency of spatial locations that is known to discriminate controls from synaesthetes. We document, for the first time, the sensitivity and specificity of such a test and suggest a diagnostic cut-off point for discriminating between the groups based on the area bounded by different placement attempts with the same item

Propiverinium picrate

The title compound [systematic name: 4-(2,2-diphenyl-2-prop­oxyacet­oxy)-1-methyl­piperidin-1-ium picrate], C23H30NO3 +·C6H2N3O7 −, crystallizes as a salt with one cation–anion (propiverinium picrate) pair in the asymmetric unit. A significant number of conformational changes are observed between the crystalline environment of this cation–anion salt and that of a density functional theory (DFT) calculation of the geometry-optimized structure. The angle between the dihedral planes of the two benzyl rings in the propiverinium cation increases by 14.4 (0)° from that of the crystalline environment. The dihedral angles between the mean planes of each of the benzyl rings and the mean plane of the piperidine increase by 2.0 (8) and 12.3 (5)°. The angles between the mean plane of the acetate group and the mean planes of the inter­connected piperidine group and the two benzyl rings decrease by 0.2 (1), 7.4 (6) and 3.2 (2)°, respectively. The mean plane of the phenolate group in the anion changes by +22.6 (9), +22.1 (1) and −2.8 (6)° from the mean planes of the piperidine and benzyl rings in the cation, respectively. In the crystal, a bifurcated N—H⋯(O,O) hydrogen bond and a weak C—H⋯π ring inter­action help to establish the packing. The two O atoms of the p-NO2 group are disordered with occupancies 0.825 (10):0.175 (10)

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

Cytochrome bd is a tri-heme (b558, b595, d) respiratory oxygen reductase that is found in many bacteria including pathogenic species. It couples the electron transfer from quinol to O2 with generation of an electrochemical proton gradient. We examined photolysis and subsequent recombination of CO with isolated cytochrome bd from Escherichia coli in oneelectron reduced (MV) and fully reduced (R) states by microsecond time-resolved absorption spectroscopy at 532-nm excitation. Both Soret and visible band regions were examined. CO photodissociation from MV enzyme possibly causes fast (t,1.5 ms) electron transfer from heme d to heme b595 in a small fraction of the protein, not reported earlier. Then the electron migrates to heme b558 (t,16 ms). It returns from the b-hemes to heme d with t,180 ms. Unlike cytochrome bd in the R state, in MV enzyme the apparent contribution of absorbance changes associated with CO dissociation from heme d is small, if any. Photodissociation of CO from heme d in MV enzyme is suggested to be accompanied by the binding of an internal ligand (L) at the opposite side of the heme. CO recombines with heme d (t,16 ms) yielding a transient hexacoordinate state (CO-Fe2+ -L). Then the ligand slowly (t,30 ms) dissociates from heme d. Recombination of CO with a reduced heme b in a fraction of the MV sample may also contribute to the 30-ms phase. In R enzyme, CO recombines to heme d (t,20 ms), some heme b558 (t,0.2–3 ms), and finally migrates from heme d to heme b595 (t,24 ms) in ,5% of the enzyme population. Data are consistent with the recent nanosecond study of Rappaport et al. conducted on the membranes at 640-nm excitation but limited to the Soret band. The additional phases were revealed due to differences in excitation and other experimental conditions

Identificación y análisis de los recursos económicos asignados a la segunda locomotora. Evolución, aciertos y desaciertos

Con la elaboración del presente documento, se pretende identificar y analizar los recursos económicos asignados a una de las locomotoras del gobierno del presidente Juan Manuel Santos en el marco de su plan de desarrollo Prosperidad para todos y el impacto social de esta asignación de recursos en el agro Colombiano, Así mismo evaluar el cumplimiento de dicha política publica y la generación de bienestar social en la población."With the production of the present document, one tries to identify and to analyze the economic resources assigned to one of the locomotives of the government of the president Juan Manuel Santos in the frame of his plan of development "" Prosperity for all "" and the social impact of this assignment of resources in the Colombian agro, Likewise to evaluate the fulfillment of the above mentioned politics publishes and the generation of social well-being in the population.