Quantum state tomography by continuous measurement and compressed sensing

The need to perform quantum state tomography on ever larger systems has spurred a search for methods that yield good estimates from incomplete data. We study the performance of compressed sensing (CS) and least squares (LS) estimators in a fast protocol based on continuous measurement on an ensemble of cesium atomic spins. Both efficiently reconstruct nearly pure states in the 16-dimensional ground manifold, reaching average fidelities FCS = 0.92 and FLS = 0.88 using similar amounts of incomplete data. Surprisingly, the main advantage of CS in our protocol is an increased robustness to experimental imperfections

Strong mass effect on ion beam mixing in metal bilayers

Molecular dynamics simulations have been used to study the mechanism of ion beam mixing in metal bilayers. We are able to explain the ion induced low-temperature phase stability and melting behavior of bilayers using only a simple ballistic picture up to 10 keV ion energies. The atomic mass ratio of the overlayer and the substrate constituents seems to be a key quantity in understanding atomic mixing. The critical bilayer mass ratio of $\delta < 0.33$ is required for the occurrence of a thermal spike (local melting) with a lifetime of $\tau > 0.3$ ps at low-energy ion irradiation (1 keV) due to a ballistic mechanism. The existing experimental data follow the same trend as the simulated values.Comment: 4 pages, 4 figures, preprin

Introduction: Examined Live – An Epistemological Exchange Between Philosophy and Cultural Psychology on Reflection

Besides the general agreement about the human capability of reflection, there is a large area of disagreement and debate about the nature and value of “reflective scrutiny” and the role of “second-order states” in everyday life. This problem has been discussed in a vast and heterogeneous literature about topics such as epistemic injustice, epistemic norms, agency, understanding, meta-cognition etc. However, there is not yet any extensive and interdisciplinary work, specifically focused on the topic of the epistemic value of reflection. This volume is one of the first attempts aimed at providing an innovative contribution, an exchange between philosophy, epistemology and psychology about the place and value of reflection in everyday life. Our goal in the next sections is not to offer an exhaustive overview of recent work on epistemic reflection, nor to mimic all of the contributions made by the chapters in this volume. We will try to highlight some topics that have motivated a new resumption of this field and, with that, drawing on chapters from this volume where relevant. Two elements defined the scope and content of this volume, on the one hand, the crucial contribution of Ernest Sosa, whose works provide original and thought-provoking contributions to contemporary epistemology in setting a new direction for old dilemmas about the nature and value of knowledge, giving a central place to reflection. On the other hand, the recent developments of cultural psychology, in the version of the “Aalborg approach”, reconsider the object and scope of psychological sciences, stressing that “[h]uman conduct is purposeful”

Thermodynamic limits of sperm swimming precision

Sperm swimming is crucial to fertilise the egg, in nature and in assisted reproductive technologies. Modelling the sperm dynamics involves elasticity, hydrodynamics, internal active forces, and out-of-equilibrium noise. Here we demonstrate experimentally the relevance of energy dissipation for sperm beating fluctuations. For each motile cell, we reconstruct the time-evolution of the two main tail's spatial modes, which together trace a noisy limit cycle characterised by a maximum level of precision $p_{max}$. Our results indicate $p_{max} \sim 10^2 s^{-1}$, remarkably close to the estimated precision of a dynein molecular motor actuating the flagellum, which is bounded by its energy dissipation rate according to the Thermodynamic Uncertainty Relation. Further experiments under oxygen deprivation show that $p_{max}$ decays with energy consumption, as it occurs for a single molecular motor. Both observations can be explained by conjecturing a high level of coordination among the conformational changes of dynein motors. This conjecture is supported by a theoretical model for the beating of an ideal flagellum actuated by a collection of motors, including a motor-motor nearest neighbour coupling of strength $K$: when $K$ is small the precision of a large flagellum is much higher than the single motor one. On the contrary, when $K$ is large the two become comparable.Comment: Main Text with Appendices (14 pages, 9 figures) plus Supplementary Information, Accepted for Publication in PRX-Lif

First results from the Very Small Array -- IV. Cosmological parameter estimation

We investigate the constraints on basic cosmological parameters set by the first compact-configuration observations of the Very Small Array (VSA), and other cosmological data sets, in the standard inflationary LambdaCDM model. Using a weak prior 40 < H_0 < 90 km/s/Mpc and 0 < tau < 0.5 we find that the VSA and COBE_DMR data alone produce the constraints Omega_tot = 1.03^{+0.12}_{-0.12}, Omega_bh^2 = 0.029^{+0.009}_{-0.009}, Omega_cdm h^2 = 0.13^{+0.08}_{-0.05} and n_s = 1.04^{+0.11}_{-0.08} at the 68 per cent confidence level. Adding in the type Ia supernovae constraints, we additionally find Omega_m = 0.32^{+0.09}_{-0.06} and Omega_Lambda = 0.71^{+0.07}_{-0.07}. These constraints are consistent with those found by the BOOMERanG, DASI and MAXIMA experiments. We also find that, by combining all the recent CMB experiments and assuming the HST key project limits for H_0 (for which the X-ray plus Sunyaev--Zel'dovich route gives a similar result), we obtain the tight constraints Omega_m=0.28^{+0.14}_{-0.07} and Omega_Lambda= 0.72^{+0.07}_{-0.13}, which are consistent with, but independent of, those obtained using the supernovae data.Comment: 10 pages, 6 figures, MNRAS in pres

Normative Alethic Pluralism

Some philosophers have argued that truth is a norm of judgement and have provided a variety of formulations of this general thesis. In this paper, I shall side with these philosophers and assume that truth is a norm of judgement. What I am primarily interested in here are two core questions concerning the judgement-truth norm: (i) what are the normative relationships between truth and judgement? And (ii) do these relationships vary or are they constant? I argue for a pluralist picture—what I call Normative Alethic Pluralism (NAP)—according to which (i) there is more than one correct judgement-truth norm and (ii) the normative relationships between truth and judgement vary in relation to the subject matter of the judgement. By means of a comparative analysis of disagreement in three areas of the evaluative domain—refined aesthetics, basic taste and morality—I show that there is an important variability in the normative significance of disagreement—I call this the variability conjecture. By presenting a variation of Lynch’s scope problem for alethic monism, I argue that a monistic approach to the normative function of truth is unable to vindicate the conjecture. I then argue that normative alethic pluralism provides us with a promising model to account for it

Enfermedad respiratoria en vacas Holstein alimentadas con silaje de maíz: reporte de caso

An outbreak of respiratory distress was observed in Holstein cows immediately after consuming a new batch of corn-silage, presumably due to the presence of pneumotoxic gases. Signs were observed in 10% of the cows, and characterized as tachypnea, orthopneic position, cough and notable anxiety a few minutes after offering the silage. No deaths were recorded. Mild leucocytosis was observed in the hemogram. Nutritional analysis and nitrate determination of the corn-silage revealed usual values. Nitrous oxide and methane concentration were evaluated by gas chromatography and nitrogen oxides concentration directly with a portable device, resulting in acceptable values. Although high concentrations of toxic gases could not be evidenced in the air sampled on farm, the clinical signs observed coincide with those reported in cases of exposure to gases formed during corn silage processes. A greater emphasis is required in the evaluation of the corn to be ensiled, given the possible existence of factors that can generate the accumulation of potentially toxic gases for cattle that affect negatively their health and productivity.Se describe un brote de enfermedad respiratoria en vacas Holando Argentino, inmediatamente luego del consumo de un nuevo silaje de planta entera de maíz, presuntamente con presencia de gases neumotóxicos. Se observaron signos en el 10% de las vacas, caracterizados como taquipnea, posición ortopnéica, episodios de tos y ansiedad, unos minutos luego del ofrecimiento del silaje. No se registraron muertes. En el hemograma se observó leucocitosis leve. El análisis de calidad nutricional del alimento y la concentración de nitratos en el silaje de maíz resultó con los valores habituales. Se evaluó la concentración de óxido nitroso y metano en una muestra de silaje de maíz recolectada herméticamente por cromatografía gaseosa, así como la concentración de óxidos de nitrógeno in situ con un instrumento portátil, resultando en valores aceptables. Aunque no se pudieron evidenciar concentraciones de gases elevadas en el aire del silaje muestreado en el tambo, los signos clínicos observados coinciden con los casos reportados de exposición a gases que se forman durante la fermentación del ensilado. Se debería tener en cuenta la evaluación del maíz a ser ensilado, dadas las posibilidades de que se genere la acumulación de gases potencialmente tóxicos para el ganado, que puedan afectar negativamente su salud y productividad