Low-cost error mitigation by symmetry verification

We investigate the performance of error mitigation via measurement of conserved symmetries on near-term devices. We present two protocols to measure conserved symmetries during the bulk of an experiment, and develop a zero-cost post-processing protocol which is equivalent to a variant of the quantum subspace expansion. We develop methods for inserting global and local symetries into quantum algorithms, and for adjusting natural symmetries of the problem to boost their mitigation against different error channels. We demonstrate these techniques on two- and four-qubit simulations of the hydrogen molecule (using a classical density-matrix simulator), finding up to an order of magnitude reduction of the error in obtaining the ground state dissociation curve.Comment: Published versio

Calculating energy derivatives for quantum chemistry on a quantum computer

Modeling chemical reactions and complicated molecular systems has been proposed as the `killer application' of a future quantum computer. Accurate calculations of derivatives of molecular eigenenergies are essential towards this end, allowing for geometry optimization, transition state searches, predictions of the response to an applied electric or magnetic field, and molecular dynamics simulations. In this work, we survey methods to calculate energy derivatives, and present two new methods: one based on quantum phase estimation, the other on a low-order response approximation. We calculate asymptotic error bounds and approximate computational scalings for the methods presented. Implementing these methods, we perform the world's first geometry optimization on an experimental quantum processor, estimating the equilibrium bond length of the dihydrogen molecule to within 0.014 Angstrom of the full configuration interaction value. Within the same experiment, we estimate the polarizability of the H2 molecule, finding agreement at the equilibrium bond length to within 0.06 a.u. (2% relative error).Comment: 19 pages, 1 page supplemental, 7 figures. v2 - tidied up and added example to appendice

Optimization of quantum algorithms for near-term quantum computers

This thesis covers several aspects of quantum algorithms for near-term quantum computers and its applications to quantum chemistry and material science. These aspects range from error mitigation and error modeling of a quantum computing device to a measurement scheduling to extract the relevant information of a quantum state for quantum chemistry calculations.It also presents a benchmarking study of classical optimization methods for variational quantum algorithms. Additionally, a small quantum simulation is performed on a cloud-based quantum computer to understand the bottlenecks of such infrastructure. Finally, a method to calculate energy derivatives on a quantum computer, a relevant figure for quantum chemistry calculations.Algorithms and the Foundations of Software technolog

Kinetics of Particles Adsorption Processes Driven by Diffusion

The kinetics of the deposition of colloidal particles onto a solid surface is analytically studied. We take into account both the diffusion of particles from the bulk as well as the geometrical aspects of the layer of adsorbed particles. We derive the first kinetic equation for the coverage of the surface (a generalized Langmuir equation) whose predictions are in agreement with recent simulation results where diffusion of particles from the bulk is explicitly considered.Comment: 4 page

Insights of microorganisms role in rice and rapeseed wastes as potential sorbents for metal removal

Altres ajuts: acord transformatiu CRUE-CSICRice and rapeseed agricultural wastes, as nonliving biomass, are proposed for heavy metal remediation in polluted effluents (chromium, cadmium, copper and lead). The physicochemical characterization of these biomasses shows that the surface of both sorbents is negatively charged (zeta potential), the surface area of sorbents is 4.39 and 40.7 (Brunauer-Emmett-Teller), and the main functional groups are carboxylic and hydroxyl (attenuated total reflection Fourier-transform infrared spectroscopy). The main purpose of this work is to evaluate the insights of microorganisms associated with these nonliving biomasses in the removal of heavy metals from synthetic aqueous solutions, adjusted at pH 4.0 (as the best acidic condition for the sorption process). The isolates (Bacillus genus in rice and Escherichia, Micrococcus and Staphylococcus genus in rapeseed) remove heavy metals from mentioned solutions, mainly in consortia, with contribution percentage over than 80% of total metals. In addition, when they are present in biomass, they provide an additional metal removal effect, especially in rapeseed biomass system and with multiple heavy metals aqueous solutions: i.e. Cr(III) removal, at 4 mmol/L, increases from 70 to 100%. This knowledge makes possible the use of the nonliving biomasses with no need for any special pretreatment against the microorganisms, prior to their use as metal sorbents that implies their good feasibility for application from an economical point of view

Massive Loss of Proprioceptive Ia Synapses in Rat Spinal Motoneurons after Nerve Crush Injuries in the Postnatal Period

Altres ajuts: NIH-NINDS R01 NS11196Peripheral nerve injuries (PNIs) induce the retraction from the ventral horn of the synaptic collaterals of Ia afferents injured in the nerve, effectively removing Ia synapses from α-motoneurons. The loss of Ia input impairs functional recovery and could explain, in part, better recovery after PNIs with better Ia synaptic preservation. Synaptic losses correlate with injury severity, speed, and efficiency of muscle reinnervation and requires ventral microglia activation. It is unknown whether this plasticity is age dependent. In neonates, axotomized motoneurons and sensory neurons undergo apoptosis, but after postnatal day 10 most survive. The goal of this study was to analyze vesicular glutamate transporter 1 (VGluT1)-labeled Ia synapses (which also include II afferents) after nerve crush in 10 day old rats, a PNI causing little Ia/II synapse loss in adult rats. We confirmed fast and efficient reinnervation of leg muscles; however, a massive number of VGluT1/Ia/II synapses were permanently lost. This synapse loss was similar to that after more severe nerve injuries involving full transection in adults. In adults, disappearance of ventrally directed Ia/II collaterals targeting α-motoneurons was associated with a prolonged microglia reaction and a CCR2 mechanism that included infiltration of CCR2 blood immune cells. By contrast, microgliosis after P10 injuries was fast, resolved in about a week, and there was no evidence of peripheral immune cell infiltration. We conclude that VGluT1/Ia/II synapse loss in young animals differs in mechanism, perhaps associated with higher microglia synaptic pruning activity at this age and results in larger losses after milder nerve injuries

Studying bath exhaustion as a method to apply microcapsules on fabrics

[EN] Textile industry is one of the fields that have increased their consumption of microcapsules. They can be applied to textiles using different methods, such as, padding, bath exhaustion, spraying and foaming. Although the most extended industrial application is by padding, commercial brands also suggest bath exhaustion as a possible procedure. In the research reported herein, bath exhaustion treatments are compared to padding. X-ray photoelectronic spectroscopy (XPS) technique showed that it was a suitable method to detect microcapsules¿presence on fabric surface. Results reported that high concentrations were required to obtain similar behaviours to those of padding. Moreover, we suggested reusing bath exhaustion baths, in order to minimise the loss of so much product in wastewater. We concluded that it was not possible because microcapsules de flate following contact with water for a per- iod of time, and what is more interesting, microcapsule preparation must be done immediately before use, so as to avoid microcapsule de flation due to contact with water.Authors gratefully acknowledge the financial support received by this research project from the Spanish government in the programme "Plan Nacional 2008-2011" reference Mat 2009-14210-C02-01.Bonet Aracil, MA.; Capablanca Francés, L.; Monllor Pérez, P.; Díaz García, P.; Montava Seguí, IJ. (2012). Studying bath exhaustion as a method to apply microcapsules on fabrics. Journal of the Textile Institute. 103(6):629-635. doi:10.1080/00405000.2011.596665S6296351036Chang, C. P., Yamamoto, T., Kimura, M., Sato, T., Ichikawa, K., & Dobashi, T. (2003). Release characteristics of an azo dye from poly(ureaurethane) microcapsules. Journal of Controlled Release, 86(2-3), 207-211. doi:10.1016/s0168-3659(02)00366-8Fan, Y. F., Zhang, X. ., Wang, X. ., Li, J., & Zhu, Q. . (2004). Super-cooling prevention of microencapsulated phase change material. Thermochimica Acta, 413(1-2), 1-6. doi:10.1016/j.tca.2003.11.006Giroud, F., Pernot, J. M., Brun, H., & Pouyet, B. (1995). Optimization of microencapsulation of acrylic adhesives. Journal of Microencapsulation, 12(4), 389-400. doi:10.3109/02652049509087251Gisbert, J., Ibañez, F., Bonet, M., Monllor, P., Díaz, P., & Montava, I. (2009). Increasing hydration of the epidermis by microcapsules in sterilized products. Journal of Applied Polymer Science, 113(4), 2282-2286. doi:10.1002/app.30210Hawlader, M. N. A., Uddin, M. S., & Khin, M. M. (2003). Microencapsulated PCM thermal-energy storage system. Applied Energy, 74(1-2), 195-202. doi:10.1016/s0306-2619(02)00146-0Kapuśniak, J., & Tomasik, P. (2006). Lipid microencapsulation in starch. Journal of Microencapsulation, 23(3), 341-348. doi:10.1080/02652040600687571Li, S., Lewis, J. E., Stewart, N. M., Qian, L., & Boyter, H. (2008). Effect of finishing methods on washing durability of microencapsulated aroma finishing. Journal of the Textile Institute, 99(2), 177-183. doi:10.1080/00405000701489701Long, Y., York, D., Zhang, Z., & Preece, J. A. (2009). Microcapsules with low content of formaldehyde: preparation and characterization. Journal of Materials Chemistry, 19(37), 6882. doi:10.1039/b902832cMadene, A., Jacquot, M., Scher, J., & Desobry, S. (2006). Flavour encapsulation and controlled release - a review. International Journal of Food Science and Technology, 41(1), 1-21. doi:10.1111/j.1365-2621.2005.00980.xMonllor, P., Bonet, M. A., & Cases, F. (2007). Characterization of the behaviour of flavour microcapsules in cotton fabrics. European Polymer Journal, 43(6), 2481-2490. doi:10.1016/j.eurpolymj.2007.04.004Monllor, P., Sánchez, L., Cases, F., & Bonet, M. A. (2009). Thermal Behavior of Microencapsulated Fragrances on Cotton Fabrics. Textile Research Journal, 79(4), 365-380. doi:10.1177/0040517508097520Monllor, P., Capablanca, L., Gisbert, J., Díaz, P., Montava, I., & Bonet, Á. (2009). Improvement of Microcapsule Adhesion to Fabrics. Textile Research Journal, 80(7), 631-635. doi:10.1177/0040517509346444Nelson, G. (2008). Microencapsulation in textile finishing. Review of Progress in Coloration and Related Topics, 31(1), 57-64. doi:10.1111/j.1478-4408.2001.tb00138.xNelson, G. (2002). Application of microencapsulation in textiles. International Journal of Pharmaceutics, 242(1-2), 55-62. doi:10.1016/s0378-5173(02)00141-2Paya, J.G., Bonet, M.A., Aboy, P.M.R. & Perez, P.M. (2010). Insect Repellent Textile. US Patent 2010/0183690 A1.Rjiba, N., Nardin, M., Drean, J.-Y., & Frydrych, R. (2009). Comparison of surfaces properties of different types of cotton fibers by inverse gas chromatography. Journal of Polymer Research, 17(1), 25-32. doi:10.1007/s10965-009-9286-7SAWADA, K., & URAKAWA, H. (2005). Preparation of photosensitive color-producing microcapsules utilizing in situ polymerization method. Dyes and Pigments, 65(1), 45-49. doi:10.1016/j.dyepig.2004.06.021Stolnik, S., Illum, L., & Davis, S. S. (1995). Long circulating microparticulate drug carriers. Advanced Drug Delivery Reviews, 16(2-3), 195-214. doi:10.1016/0169-409x(95)00025-3Topalovic, T., Nierstrasz, V. A., Bautista, L., Jocic, D., Navarro, A., & Warmoeskerken, M. M. C. G. (2007). Analysis of the effects of catalytic bleaching on cotton. Cellulose, 14(4), 385-400. doi:10.1007/s10570-007-9120-5Wegmüller, R., Zimmermann, M. B., Bühr, V. G., Windhab, E. J., & Hurrell, R. F. (2006). Development, Stability, and Sensory Testing of Microcapsules Containing Iron, Iodine, and Vitamin A for Use in Food Fortification. Journal of Food Science, 71(2), S181-S187. doi:10.1111/j.1365-2621.2006.tb08923.xFras Zemljič, L., Strnad, S., Šauperl, O., & Stana-Kleinschek, K. (2009). Characterization of Amino Groups for Cotton Fibers Coated with Chitosan. Textile Research Journal, 79(3), 219-226. doi:10.1177/0040517508093592ZHANG, Z. (1999). Mechanical strength of single microcapsules determined by a novel micromanipulation technique. Journal of Microencapsulation, 16(1), 117-124. doi:10.1080/026520499289365Zhang, X., Tao, X., Yick, K., & Wang, X. (2003). Structure and thermal stability of microencapsulated phase-change materials. Colloid and Polymer Science, 282(4), 330-336. doi:10.1007/s00396-003-0925-

Aberrant perineuronal nets alter spinal circuits, impair motor function, and increase plasticity

Altres ajuts: acords transformatius de la UABPerineuronal nets (PNNs) are a specialized extracellular matrix that have been extensively studied in the brain. Cortical PNNs are implicated in synaptic stabilization, plasticity inhibition, neuroprotection, and ionic buffering. However, the role of spinal PNNs, mainly found around motoneurons, is still unclear. Thus, the goal of this study is to elucidate the role of spinal PNNs on motor function and plasticity in both intact and spinal cord injured mice. We used transgenic mice lacking the cartilage link protein 1 (Crtl1 KO mice), which is implicated in PNN assembly. Crtl1 KO mice showed disorganized PNNs with an altered proportion of their components in both motor cortex and spinal cord. Behavioral and electrophysiological tests revealed motor impairments and hyperexcitability of spinal reflexes in Crtl1 KO compared to WT mice. These functional outcomes were accompanied by an increase in excitatory synapses around spinal motoneurons. Moreover, following spinal lesions of the corticospinal tract, Crtl1 KO mice showed increased contralateral sprouting compared to WT mice. Altogether, the lack of Crtl1 generates aberrant PNNs that alter excitatory synapses and change the physiological properties of motoneurons, overall altering spinal circuits and producing motor impairment. This disorganization generates a permissive scenario for contralateral axons to sprout after injury

A unified approach for a posteriori high-order curved mesh generation using solid mechanics

The paper presents a unified approach for the a posteriori generation of arbitrary high-order curvilinear meshes via a solid mechanics analogy. The approach encompasses a variety of methodologies, ranging from the popular incremental linear elastic approach to very sophisticated non-linear elasticity. In addition, an intermediate consistent incrementally linearised approach is also presented and applied for the first time in this context. Utilising a consistent derivation from energy principles, a theoretical comparison of the various approaches is presented which enables a detailed discussion regarding the material characterisation (calibration) employed for the different solid mechanics formulations. Five independent quality measures are proposed and their relations with existing quality indicators, used in the context of a posteriori mesh generation, are discussed. Finally, a comprehensive range of numerical examples, both in two and three dimensions, including challenging geometries of interest to the solids, fluids and electromagnetics communities, are shown in order to illustrate and thoroughly compare the performance of the different methodologies. This comparison considers the influence of material parameters and number of load increments on the quality of the generated high-order mesh, overall computational cost and, crucially, the approximation properties of the resulting mesh when considering an isoparametric finite element formulation