Multi-scale tensor network architecture for machine learning

We present an algorithm for supervised learning using tensor networks, employing a step of data pre-processing by coarse-graining through a sequence of wavelet transformations. These transformations are represented as a set of tensor network layers identical to those in a multi-scale entanglement renormalization ansatz tensor network. We perform supervised learning and regression tasks through a model based on a matrix product states (MPSs) acting on the coarse-grained data. Because the entire model consists of tensor contractions (apart from the initial non-linear feature map), we can adaptively fine-grain the optimized MPS model ‘backwards’ through the layers with essentially no loss in performance. The MPS itself is trained using an adaptive algorithm based on the density matrix renormalization group algorithm. We test our methods by performing a classification task on audio data and a regression task on temperature time-series data, studying the dependence of training accuracy on the number of coarse-graining layers and showing how fine-graining through the network may be used to initialize models which access finer-scale features.

Theoretical study of electrorheological behavior of a nematic liquid crystal confined by two cylindrical surfaces with different anchoring energies

Electrorheological response of a nematic liquid crystal confined in the region between two coaxial and rotating circular cylinders is studied theoretically. Utilizing weak anchoring conditions, the physical properties of 4-n-pentyl-4-cyanobiphenyl (5CB), nonslip boundary conditions, and contrasting surface anchoring energies, we numerically obtain the equilibrium configurations for the nematic director under the influence of an external low-frequency radial electric field and the corresponding (angular) velocity profiles. The Fréedericksz transition is parametrized by the cylinders' radii ratio for different values of the surface energies. The averaged apparent viscosity of the nematic is calculated also.

Optical spectra of graded pitch structurally chiral media

We study optical spectra when circularly polarized light normally impinges on a structurally chiral medium (SCM) with variable pitch which locally has a [Formula: see text] point group symmetry. In this case, a structural period is defined as a length along the nonhomogeneity axis, where the director rotates a full turn. We considered three different pitch gradients: (a) The pitch value is constant in each structural period and it uniformly increases or decreases in subsequent periods. (b) The pitch value linearly increases or decreases from the initial to the final structural period. (c) The pitch value linearly increases or decreases in a period, with identical periods in the slab. In the first and second case, spectra show a Bragg-type broad-band. It is broader as the difference between the initial and final pitch value in the SCM increases. However, for the third case, there are regions where waves are mainly transmitted as right circularly polarized (RCP) or left circularly polarized (LCP) waves. Inside these regions there are multiple narrow bands for both RCP and LCP waves. Meanwhile, reflexion is almost absent in the spectra except for the optical bands, where there is reflexion for RCP and LCP waves. Thus, spectra exhibit conversion of RCP waves in LCP (LCP in RCP) waves. Moreover, we found that the center frequency of the bands are harmonics of the center frequency of the first band.

Omnidirectional optical spectra for a nanocomposite cholesteric elastomer

We perform a theoretical model for studying the propagation of electromagnetic waves, within a cholesteric elastomer slab, doped with metallic inclusions aleatorily distributed, whose corresponding dielectric properties can be expressed in terms of a resonant effective uniaxial tensor. We have obtained an omnidirectional narrow conducting band and two narrow reflection bands created in the optical spectrum for right and left circularly polarized light, as well as narrow reflection bands for right circularly polarized light. We have found that the transmission and reflection spectra depend on light incidence angle and the filling fraction of metallic inclusions.

NDM-1 carbapenemase in Acinetobacter baumannii sequence type 32 in Ecuador

Objectives

To describe a clinical case of Acinetobacter baumannii sequence type (ST) 32 harbouring a New Delhi metallo-β-lactamase (NDM) in Ecuador.

Methods

We used multilocus sequence typing (MLST) to confirm the bacterial species and the sequence type of an A. baumannii isolate. We used synergy with the imipenem–EDTA disc method and the carbapenem inactivation method (CIM) to determine carbapenemase production; the presence of a carbapenemase gene was confirmed by PCR amplification and amplicon sequencing.

Results

Molecular characterization revealed the presence of A. baumannii ST32 harbouring the bla_NDM-1 gene in Ecuador. The bla_NDM-1 gene was isolated through PCR and amplified from a purified plasmid.

Conclusions

To the best of our knowledge, this is the first report of A. baumannii ST32 harbouring the bla_NDM-1 gene.

Saturation and stability of nonlinear photonic crystals

We consider a one-dimensional photonic crystal made by an infinite set of nonlinear nematic films immersed in a linear dielectric medium. The thickness of each equidistant film is negligible and its refraction index depends continuously on the electric field intensity, giving rise to all the involved nonlinear terms, which joints from a starting linear index for negligible amplitudes to a final saturation index for extremely large field intensities. We show that the nonlinear exact solutions of this system form an intensity-dependent band structure which we calculate and analyze. Next, we ponder a finite version of this system; that is, we take a finite array of linear dielectric stacks of the same size separated by the same nonlinear extremely thin nematic slabs and find the reflection coefficients for this arrangement and obtain the dependence on the wave number and intensity of the incident wave. As a final step we analyze the stability of the analytical solutions of the nonlinear crystal by following the evolution of an additive amplitude to the analytical nonlinear solution we have found here. We discuss our results and state our conclusions.

A variant in ANKK1 modulates acute subjective effects of cocaine: a preliminary study

This study aimed to evaluate whether functional variants in the ankyrin repeat and kinase domain-containing 1 (ANKK1) gene and/or the dopamine receptor D2 (DRD2) gene modulate the subjective effects (reward or non-reward response to a stimulus) produced by cocaine administration. Cocaine-dependent participants (N = 47) were administered 40 mg of cocaine or placebo at time 0, and a subjective effects questionnaire (visual analog scale) was administered 15 min prior to cocaine administration, and at 5, 10, 15 and 20 min following administration. The influence of polymorphisms in the ANKK1 and DRD2 genes on subjective experience of cocaine in the laboratory was tested. Participants with a T allele of ANKK1 rs1800497 experienced greater subjective 'high' (P = 0.00006), 'any drug effect' (P = 0.0003) and 'like' (P = 0.0004) relative to the CC genotype group. Although the variant in the DRD2 gene was shown to be associated with subjective effects, linkage disequilibrium analysis revealed that this association was driven by the ANKK1 rs1800497 variant. A participant's ANKK1 genotype may identify individuals who are likely to experience greater positive subjective effects following cocaine exposure, including greater 'high' and 'like', and these individuals may have increased vulnerability to continue using cocaine or they may be at greater risk to relapse during periods of abstinence. However, these results are preliminary and replication is necessary to confirm these findings.

Propagation of electromagnetic waves in stochastic helical media

We have developed a model for studying the axial propagation of elliptically polarized electromagnetic waves in a spatially random helical media. We start by writing Maxwell equations for a structurally chiral medium whose dielectric permittivities, polar, and helical angles contain both a stochastic contribution and a deterministic one. We write the electromagnetic equations into a Marcuvitz-Schwigner representation to transform them afterward in a simpler expression by using the Oseen transformation. We exhibit that in the Oseen frame the Marcuvitz-Schwigner equations turns out to be a linear vector stochastic system of differential equations with multiplicative noise. Applying to the resulting equation a formalism for treating stochastic differential equations, we find the governing equations for the first moments of the electromagnetic field amplitudes for a general autocorrelation function for the system diffractive indexes, and calculate their corresponding band structure for a particular spectral noise density. We have shown that the average resulting electromagnetic fields exhibit a decaying exponential dependence which stems from by dissipation and the presence of qualitative modifications in the band structure including a considerable widening of the band gap and the existence of new local maxima for the modes without a band gap.

Increased incidence of CPR-related rib fractures in infants--is it related to changes in CPR technique?

OBJECTIVE

A recent increase in the number of infants presenting at autopsy with rib fractures associated with cardio-pulmonary resuscitation (CPR) precipitated a study to determine whether such a phenomenon was related to recent revision of paediatric resuscitation guidelines.

METHODS

We conducted a review of autopsy reports from 1997 to 2008 on 571 infants who had CPR performed prior to death.

RESULTS

Analysis of the study population revealed CPR-related rib fractures in 19 infants (3.3%), 14 of whom died in the 2006-2008 period. The difference in annual frequency of CPR-related fractures between the periods before and after revision of paediatric CPR guidelines was statistically highly significant.

CONCLUSIONS

The findings indicate that CPR-associated rib fractures have become more frequent in infants since changes in CPR techniques were introduced in 2005. This has important implications for both clinicians and pathologists in their assessment of rib fractures in this patient population.

Threshold field for a nematic liquid crystal confined between two coaxial cylinders

We consider a nematic liquid crystal constrained by two coaxial cylinders under the action of low-frequency axial or radial electric fields. Assuming an initially hybrid configuration, we find the equilibrium texture of the nematic subjected to weak anchoring boundary conditions on both cylindrical surfaces. We analyze the distinct textures of the nematic as a function of the strength of the interaction of the nematic with the sidewalls, the radii ratio of the cylinders, and the applied electric field. Also, for each radii ratio and strength of the nematic-surface interaction, we determine the critical field for which a complete alignment of the nematic liquid crystal occurs.

Geometrical analysis of the electro-optical effect in nematic droplets

Using the boundary-layer approach, we study the radial-axial transition in a nematic sphere in the presence of an external field. We calculate analytically an asymptotic expression for the nematic configuration subject to an external low frequency field. Then, we consider an incident plane wave crossing a nematic droplet immersed in an isotropic matrix under the presence of a low frequency field. We calculate the ray trajectories within the optical limit for various values of the external field and find the ray deviation as a function of the incident position parametrized by the magnitude of the field.

Spatial solitons in chiral media

We study theoretically the nonlinear propagation of a narrow optical wave packet through a cholesteric liquid crystal. We derive the equations governing the weakly nonlinear dynamics of an optical field by taking into account the coupling with the liquid crystal. We constructed the solution as the superposition of four narrow wave packets centered around the linear eigenmodes of the helical structure whose corresponding envelopes A are slowly varying functions of their arguments. We found a system of four coupled equations to describe the resulting vector wave packet which has some integration constants and that under special conditions reduces to the nonlinear Schrödinger equation with space-dependent coefficients. We solved this equation both, using a variational approach and performing numerical calculations. We calculated analytically the soliton spatial scales, the transported power, the nonlinear refraction index, and its wavelength dependence, showing that this has its maxima at the edges of the reflection band. We also exhibit the existence of some other exact but non-self-focused solutions.

Electrically controlled total internal reflection in nematic hybrid cells

In this work, we show theoretically how the trajectories of an optical beam propagating in a planar-homeotropic hybrid nematic crystal cell can be modified by applying a low frequency electric field perpendicular to the cell. We use a previously developed formalism for describing the propagation of a polarized beam through the cell. We include a low frequency electric energy for the calculation of the equilibrium orientational configurations of the director's field. The presence of the electric field gives rise to trajectories showing a nontrivial dependence of the beam's range and penetration length with the intensity of the applied electric field.

Absorption effects in liquid crystal waveguides

An analytical and numerical study of the propagation of optical fields through a nematic hybrid slab is developed. We take into account explicitly the absorption of radiation by the liquid crystal by introducing a complex dielectric tensor. For a low intensity beam we first derive the eikonal equation and from it we calculate the ray trajectories in the optical limit. We show that in the presence of absorption, there are no caustics within the slab. Then we consider the WKB limit and calculate the field transverse magnetic modes, their number and their cutoff frequencies. We show that for both limits the agreement between our analytical and numerical results for the propagation constants is excellent, while there are larger differences in the analytically and numerically calculated field amplitudes. These differences show that absorption effects are important for this quantity and have their origin in the fact that the chosen parameter values in our exact numerical calculations, strictly speaking, do not lie within the limits of validity of the WKB approximation. Although a more precise comparison between these approaches requires the use of different sets of values of the relevant parameters, our analysis shows the effects and complications arising from the inclusion of absorption. Finally, we discuss the scope and limitations of our approach.

Standard and embedded solitons in nematic optical fibers

A model for a non-Kerr cylindrical nematic fiber is presented. We use the multiple scales method to show the possibility of constructing different kinds of wave packets of transverse magnetic modes propagating through the fiber. This procedure allows us to generate different hierarchies of nonlinear partial differential equations which describe the propagation of optical pulses along the fiber. We go beyond the usual weakly nonlinear limit of a Kerr medium and derive a complex modified Korteweg-de Vries equation (CM KdV) which governs the dynamics for the amplitude of the wave packet. In this derivation the dispersion, self-focussing, and diffraction in the nematic fiber are taken into account. It is shown that this CM KdV equation has two-parameter families of bright and dark complex solitons. We show analytically that under certain conditions, the bright solitons are actually double-embedded solitons. We explain why these solitons do not radiate at all, even though their wave numbers are contained in the linear spectrum of the system. We study (numerically and analytically) the stability of these solitons. Our results show that these embedded solitons are stable solutions, which is an interesting property since in most systems the embedded solitons are weakly unstable solutions. Finally, we close the paper by making comments on the advantages as well as the limitations of our approach, and on further generalizations of the model and method presented.

Twist defects in helical sonic structures

We analyze theoretically both the acoustic wave propagation in periodic media made of anisotropic materials whose stiffness tensor is uniformly rotating along a given axis x(3) and the defect mode produced by twisting about x(3) one part of the helical structure with respect to the other. Within the Bragg band of the periodic structure, the twist defect gives rise to a resonant mode that is a superposition of two standing waves: one localized with exp(-gamma|x(3)|) dependence centered at the defect and the other extended over the whole sample. The ratio between the amplitudes of the localized and nonlocalized waves depends sharply on both the twist angle and the elastic anisotropy, and can assume huge values. The defect mode and the resonance frequency omega(0) are defined by fully analytical and very simple expressions. Finally, we discuss how around omega(0), a finite sample acts as a frequency filter for circularly polarized shear waves, whose bandwidth can be changed by many orders of magnitude by varying the sample thickness, the twist angle, or the elastic anisotropy.

Comparative endocrinology of the insulin-like growth factor-binding protein

Emerging early in chordate evolution, the IGF-regulatory axis diverged from an insulin-like predecessor into a vertebrate regulatory system specializing in cell growth activation and allied anabolic functions. Essential to the divergence of the IGF and insulin systems was an early presence of soluble IGF-binding proteins (IGFBPs), which bind IGF peptides at much higher affinity than that of the insulin receptor but at comparable affinities to that of the IGF receptor. IGFBPs have no homology with IGF receptors. Instead, IGFBPs are a derived group of proteins within a superfamily of cysteine-rich growth factors, whose members are found throughout the animal taxa. While blocking IGF actions through the insulin receptor is a fundamental role, IGFBPs evolved within the vertebrate line into centralized, 'integrators' of the endocrine growth-regulatory apparatus. IGFBPs have substantial influences on the distribution and bioavailability of IGF peptides in the cellular and physiological environments, but they have a variety of other properties. The six principal mammalian IGFBPs exhibit an array of specialized properties that appear to be derived from a complex evolutionary history (including cell membrane association, interaction with proteins that post-translationally modify them, direct IGF-independent effects on cells, and others) and they are regulated by a diversity of 'outside' factors (e.g. other hormones, metabolic status, stress). Thus, IGFBPs are multifunctional integrators having diverse physiological 'agendas'. Much less is known about IGFBPs and their properties in the other vertebrate taxa. Increasingly, however, it is being recognized that they play equally important endocrine roles, in both conserved and non-conserved ways, when compared with those currently defined in mammals. This review highlights selected 'comparative aspects' in current IGFBP research, in an attempt to view this essential group of endocrine regulators from a wider, biological perspective.

Flow dissipation effects in a nonlinear nematic fiber

Dissipative effects due to the presence of hydrodynamic flow in a cylindrical fiber whose cladding is an initially quiescent incompressible nematic liquid crystal are analyzed. An analytic and iterative solution of the nematodynamic equations coupled to the Maxwell's equations describing the propagation of a narrow wave packet of transverse magnetic modes is provided. We derive a generalized nonlinear Schröedinger equation for the amplitude of this propagating wave packet that takes into account the dissipation in the nematic's reorientation and the hydrodynamical effects. For the solitonlike solution of this equation we find that the penetration length and the real part of the nonlinear refraction index increase by a factor of 1.75, with respect to those values obtained in the absence of hydrodynamical flow. The imaginary part remains unaltered.

The structure of affect in a non-western culture: evidence for cross-cultural comparability

We investigated the structure of affect in the Filipino culture and compared our results to those in Western studies. Four samples of students (ns = 397 to 530) rated their mood for today, the past week, or in general, using near-comprehensive sets of Filipino mood adjectives. Results of exploratory and confirmatory factor analyses supported a hierarchical model of affect and the cross-cultural comparability of self-report mood dimensions (i.e., higher-order Positive and Negative Affect, plus specific affects corresponding to hypothesized universal or basic emotions). The results were more consistent with biological theories of affect than a strong social constructivist perspective.

Filipino personality structure and the big five model: a lexical approach

In lexically based studies, we derived Filipino personality dimensions and related them to the Big Five model. In Study 1, Filipino high-school and college students (N = 629) rated themselves on a near-comprehensive list of 861 Filipino (Tagalog) trait adjectives. In Study 2, Filipino high-school and college students (N = 1,531) rated 280 markers of dimensions identified in Study 1. Some students (n = 473) also completed the NEO Five-Factor Inventory. Seven comparable Filipino dimensions were identified in factor analyses in the two studies. We concluded that the dimensions we labeled Concern for Others (vs. Egotism), Conscientiousness, Gregariousness, and Intellect were quite similar to Big Five Agreeableness, Conscientiousness, Extraversion, and Intellect, respectively. The Filipino Self-Assurance dimension was most similar to Big Five Neuroticism. The Filipino Temperamentalness dimension was more complex in Big Five terms, overlapping Agreeableness, Conscientiousness, and Neuroticism. A final Filipino factor resembled a Negative Valence or Infrequency dimension. More than five factors had to be extracted to obtain Philippine dimensions resembling all of the Big Five.

Opioid receptor modulation of mossy fiber synaptogenesis: independence from long-term potentiation

Long-term potentiation (LTP) at the mossy fiber-CA3 synapse of the rat hippocampus is an NMDA receptor-independent form of synaptic plasticity that is sensitive to opioid receptor antagonists [12]. In the present study, Timm's stain, a zinc detecting histological marker commonly used to infer synaptogenesis in the mossy fiber projection, was used to examine whether synaptogenesis occurs in response to mossy fiber LTP induction in the adult rat in vivo. Seven days following the induction of mossy fiber LTP by non-seizure-inducing high-frequency stimulation of the mossy fibers, a prominent band of Timm's staining appeared bilaterally in the infrapyramidal region of the stratum oriens in area CA3. Staining was more prominent on the side contralateral to the stimulation. Systemic administration of the opioid receptor antagonist naloxone, sufficient to block mossy fiber LTP induction, did not block the development of Timm's staining in the infrapyramidal region ipsilateral to stimulation, but it did block stimulation-induced increases in Timm's staining observed contralaterally. Systemic administration of (+/-) CPP, a competitive NMDA receptor-antagonist, by contrast, did not block the induction of LTP and did not alter the increase in Timm's staining observed either ipsilaterally or contralaterally. The increase in Timm's staining in the infrapyramidal region suggests that mossy fiber synaptogenesis occurs in response to non-seizure inducing stimulation. Synaptogenesis does not appear to be directly related to opioid receptor-dependent mossy fiber LTP induction, because it occurs in the presence of naloxone which blocks LTP. The mossy fiber synaptogenesis occurring contralaterally appears to be regulated by endogenous opioid peptides, because it is blocked by naloxone.

Reproductive toxicity of commercial PCB mixtures: LOAELs and NOAELs from animal studies

This paper reviews the developmental/reproductive toxicity of commercial polychlorinated biphenyl (PCB) mixtures in animals and reports on the "no-observable-adverse-effect levels" (NOAELs) and "lowest-observable-adverse-effect levels" (LOAELs) from these studies. Identification of the lowest effective doses for reproductive toxicity of PCB mixtures is difficult because a variety of reproductive and developmental effects have been reported in several species using different commercial mixtures. Factors to be considered include sensitivity of the end point, sensitivity of species, study quality, biological plausibility, and relevance to humans. End points affected at the lowest doses (sensitive end points) included postnatal growth, development, and function. Among species for whom sensitive end points have been evaluated, a LOAEL of 0.25 mg/kg/day was identified for rodents on the basis of developmental delays in growth and behavioral function, and a LOAEL of 0.008 mg/kg/day was identified for nonhuman primates based on postnatal skin hyperpigmentation. NOAELs were not identifiable for these sensitive end points because effects were reported at the lowest doses tested.

Rapid assessment of the visual field in glaucoma using an analysis based on multiple correlations

We wished to determine which areas of the visual field contribute most strongly and most frequently to the deterioration of the visual fields in patients with high ocular pressure. The computerized analysis, using linear and multiple regressions of the findings in 382 visual fields, allowed us to select four test points sensitive enough to estimate the actual global sensitivity of the central visual field (correlation coefficient, 0.98). This system also allowed us to estimate the number of pathological points and even to classify accurately over 75% of the cases in terms of their normal or pathological condition, as well as to determine the depth of the defect. The remaining cases show that the deterioration, if it exists, is not significant. Requiring less than 1 min a threshold examination at these four test points enables us to acquire greater insight into the glaucomatous defect.