Affine diffractive beam dividers.

Diffractive optical elements that divide an input beam into a set of replicas are used in many optical applications ranging from image processing to communications. Their design requires time-consuming optimization processes, which, for a given number of generated beams, are to be separately treated for one-dimensional and two-dimensional cases because the corresponding optimal efficiencies may be different. After generalizing their Fourier treatment, we prove that, once a particular divider has been designed, its transmission function can be used to generate numberless other dividers through affine transforms that preserve the efficiency of the original element without requiring any further optimization.

Three-dimensional polarization of fields radiated by partially coherent electromagnetic cylindrical sources.

Partially coherent electromagnetic sources with cylindrical symmetry and infinite extent radiating outward are introduced. Their 3 × 3 cross-spectral density matrix is given through expansions of the field components in terms of basis functions related to the Hankel functions. The spectral density and the three-dimensional degree of polarization of such sources and the fields they radiate are examined. Several examples are presented and discussed. Among them, a class of cylindrical sources whose coherent vector modes coincide with the above basis functions is defined and studied.

Partially coherent spherical sources with spherical harmonic modes.

A class of partially coherent spherical sources is introduced whose cross-spectral density across the surface has a modal expansion made up of spherical harmonics. For such sources, the solution of the propagation problem in all the outer spaces can be written through a series of the propagated modes, which maintains the spherical harmonic structure. The main features of this class of cross-spectral densities are derived illustrating their coherence properties with examples. Attention is paid to the properties of radial coherence. In particular, it is clearly shown that sources with perfect radial coherence exist with angular coherence that is only partial.

Cylindrical partially coherent scalar sources.

Partially coherent scalar sources with cylindrical symmetry radiating outwards are introduced. Homogeneous cross-spectral densities are shown to possess angularly modulated Hankel modes, whose amplitudes are subject to a filtering process during propagation. Simple criteria for treating such sources are given. For the case of an incoherent cylinder, the number of effective modes is found and spatial coherence is shown to appear in the radiated light. The radial coherence of the radiated field is then examined. Non-homogeneous cylindrical sources are also introduced.

On-axis polarization of beams radiated by electromagnetic circularly coherent sources.

On-axis spectral density and degree of polarization of beams radiated by electromagnetic (EM) sources with circular correlations are shown to be finely controlled by changing the source parameters. We reveal, in particular, that in this beam class, unlike for all previously known stationary beams, it is possible to control independently the dynamics of the on-axis spectral density and the degree of polarization. This was enabled by the obtained analytical expression for the on-axis polarization matrix, derived for general EM sources with circular coherence and Gaussian spectral density across the source plane. A simple experimental scheme for generating a broad class of EM circularly coherent sources is devised involving only a line source, a lens, and a transparency, possibly anisotropic.

Tailoring on-axis spectral density with circularly coherent light beams.

The on-axis cross-spectral density (CSD) of a beam radiated by a stationary source with a circular coherence state and a Gaussian spectral density is obtained in the closed form. It is revealed that the on-axis CSD is expressed via the Laplace transform of the source's degree of coherence or the Hilbert transform of the corresponding pseudo-mode weighting function. Such relations enable efficient tailoring of the on-axis spectral density, as we show with a slew of numerical examples.

On z-coherence of beams radiated by Schell-model sources with Gaussian profile.

The degree of coherence and the intensity distribution on the axis of the beam radiated by a planar partially coherent source of the Schell-model type are investigated. We present an expression for the on-axis cross-spectral density which is valid for a very general Schell-model source, with the only constraint that the intensity distribution across the source is Gaussian. Furthermore, we show that such an expression takes very simple analytical forms for several commonly used degrees of coherence of the source.

On z-coherence in self-focusing.

Both the intensity distribution and the degree of coherence between pairs of points along the propagation axis (z-coherence) are derived in closed form for a phenomenon of self-focusing produced by circularly coherent light. The first confirms results previously obtained numerically, while the second exhibits new complex features. The physical interpretation is obtained by a suitable pseudo-modal expansion that suggests an analogy with a simple two-mode structure.

Sex-related differences of fatty acid-binding protein 4 and leptin levels in atrial fibrillation.

AIMS: Adiposity plays a key role in the pathogenesis of atrial fibrillation (AF). Our aim was to study the sex differences in adipokines levels according to AF burden. METHODS AND RESULTS: Two independent cohorts of patients were studied: (i) consecutive patients with AF undergoing catheter ablation (n = 217) and (ii) a control group (n = 105). (i) Adipokines, oxidative stress, indirect autonomic markers, and leucocytes mRNA levels were analysed; (ii) correlation between biomarkers was explored with heatmaps and Kendall correlation coefficients; and (iii) logistic regression and random forest model were used to determine predictors of AF recurrence after ablation. Our results showed that: (i) fatty acid-binding protein 4 (FABP4) and leptin levels were higher in women than in men in both cohorts (P < 0.01). In women, FABP4 levels were higher on AF cohort (20 ± 14 control, 29 ± 18 paroxysmal AF and 31 ± 17 ng/mL persistent AF; P < 0.01). In men, leptin levels were lower on AF cohort (22 ± 15 control, 13 ± 16 paroxysmal AF and 13 ± 11 ng/mL persistent AF; P < 0.01). (ii) In female with paroxysmal AF, there was a lower acetylcholinesterase and higher carbonic anhydrase levels with respect to men (P < 0.05). (iii) Adipokines have an important role on discriminate AF recurrence after ablation. In persistent AF, FABP4 was the best predictor of recurrence after ablation (1.067, 95% confidence interval 1-1.14; P = 0.046). CONCLUSION: The major finding of the present study is the sex-based differences of FABP4 and leptin levels according to AF burden. These adipokines are associated with oxidative stress, inflammatory and autonomic indirect markers, indicating that they may play a role in AF perpetuation.

Synthesis and characterization of non-uniformly totally polarized light beams: tutorial.

Polarization of a light beam is traditionally studied under the hypothesis that the state of polarization is uniform across the transverse section of the beam. In such a case, if the paraxial approximation is also assumed, the propagation of the beam reduces to a scalar problem. Over the last few decades, light beams with spatially variant states of polarization have attracted great attention, due mainly to their potential use in applications such as optical trapping, laser machining, nanoscale imaging, polarimetry, etc. In this tutorial, an introductory treatment of non-uniformly totally polarized beams is given. Besides a brief review of some useful parameters for characterizing the polarization distribution of such beams across transverse planes, from both local and global points of view, several methods for generating them are described. It is expected that this tutorial will serve newcomers as a starting point for further studies on the subject.

Avaliação da anestesia epidural com lidocaína associada ao tramadol ou à dexmedetomidina, em gatas submetidas à ovariosalpingohisterectomia, anestesiadas com propofol / Evaluation of epidural anesthesia with lidocaine associated to tramadol or dexmedetomidine, in cats undergoing ovariosalpingohisterectomy, anesthetized with propofol

Objetivou-se comparar os efeitos fisiológicos, analgésicos e sobre a taxa de infusão de propofol, decorrentes da anestesia epidural com lidocaína, associada ao tramadol ou à dexmedetomidina, em felinas submetidas à ovariosalpingohisterectomia (OSH). Para tal, 16 felinas hígidas foram pré-tratadas com acepromazina 0,08mg/kg/IM, utilizando-se propofol para a indução (dose-efeito) e manutenção anestésicas. Após indução, as gatas foram aleatoriamente distribuídas em dois grupos (n=8), designados: grupo lidocaína-tramadol (GLT), tratado com lidocaína (3,0mg/kg) associada ao tramadol (2,0mg/kg); e grupo lidocaína-dexmedetomidina (GLD), tratado com lidocaína (3,0mg/kg) associada à dexmedetomidina (2µg/kg), pela via epidural. Durante a OSH, a infusão de propofol foi aumentada ou reduzida, objetivando-se manutenção de plano anestésico cirúrgico. Foram avaliados os parâmetros: f, FC, SPO2, EtCO2, PAS, PAD, PAM, T°C, nos períodos pré (M1) e transoperatórios (M2 a M7); a taxa mínima de propofol necessária; o tempo de recuperação anestésica e a qualidade da analgesia pós-cirúrgica durante seis horas. Ambos os tratamentos garantiram baixas taxas mínimas de infusão de propofol, todavia o uso da dexmedetomidina resultou em bradicardia inicial, elevação da pressão arterial, maior tempo de recuperação e menor qualidade analgésica, quando comparada ao tramadol.(AU)

The aim of this study was to compare the physiological and analgesic effects and the minimum infusion rate of propofol of epidural anesthesia with lidocaine associated to tramadol or dexmedetomidine, in cats undergoing ovariosalpingohysterectomy (OSH). For this purpose, 16 healthy cats were pretreated with acepromazine (0.08mg kg -1 IM) and propofol was used for induction (dose-effect) and maintenance of anesthesia. After induction, the cats were assigned in two randomized groups (n= 8), named: Lidocaine-tramadol group (LTG), treated with lidocaine (3mg kg -1 ) associated to tramadol (2mg kg -1 ) and Lidocaine-dexmedetomidine group (LDG), treated with lidocaine (3mg kg -1 ) associated to dexmedetomidine (2g kg -1 ), by epidural route. During OSH, propofol infusion was increased or decreased, setting to maintain surgical anesthetic depth. The parameters f, HR, SPO 2 , EtCO 2 , SAP, DAP, MAP, T°C in the pre (M1) and trans-operative periods (M2 to M7); minimum infusion rate of propofol; time of anesthetic recovery and quality of postoperative analgesia during six-hour interval, were evaluated. Both protocols provided low minimum infusion rate of propofol. However, dexmedetomidine resulted in initial bradycardia, elevated blood pressure, longer recovery time, and lower analgesic quality when compared to tramadol.(AU)

Ropivacaína isolada ou associada à metadona ou à morfina, pela via epidural, em cadelas submetidas à ovário-histerectomia / Ropivacaine sole or associated to methadone or morphine, by epidural route, in bitches undergoing ovariohysterectomy

Objetivou-se avaliar os efeitos fisiológicos, sedativos e analgésicos da administração peridural de ropivacaína isolada ou associada à morfina ou à metadona. Para tal, 24 cadelas submetidas à ovário-histerectomia receberam acepromazina, e a anestesia foi induzida e mantida com propofol e isoflurano (FiO2 = 1,0), respectivamente. De acordo com o protocolo peridural, formaram-se três grupos de igual número: GR (ropivacaína - 2,0mg/kg); GRMETA (ropivacaína - 2,0mg/kg e metadona - 0,3mg/kg) e GRMORF (ropivacaína - 2,0mg/kg e morfina - 0,1mg/kg). Registraram-se os parâmetros fisiológicos intraoperatórios e os graus de sedação e analgesia pós-operatórios. No GR constataram-se maiores médias de pressões arteriais 30 minutos após a anestesia epidural em relação ao GRMETA (sistólica e média) e ao final do procedimento cirúrgico comparativamente ao GRMORF (sistólica, diastólica e média). Não foram observadas diferenças significativas entre os grupos relativamente à analgesia e ao grau de sedação pós-operatórios. A administração epidural de ropivacaína é segura e eficaz e proporciona boa analgesia, independentemente da sua associação com morfina ou metadona.(AU)

The aim of this study was to evaluate the physiological, sedative and analgesic effects of epidural administration of ropivacaine sole or associated to morphine or methadone. Twenty-four bitches were submitted to ovariohysterectomy and received acepromazine and after, propofol and isoflurane (FiO 2 = 1.0) for anesthesia induction and maintenance, respectively. Based on established epidural protocol (L7-S1), three groups were formed: GR (ropivacaine - 2.0mg/kg); GRMETA (ropivacaine - 2.0mg/kg and methadone - 0.3mg/kg) and GRMORF (ropivacaine - 2.0mg/kg and morphine - 0.1mg/kg). Intraoperative physiological parameters and degrees of postoperative sedation and analgesia were recorded. In the GR, the means of arterial pressures, 30 minutes after epidural anesthesia, were higher compared with GRMETA (systolic and mean) and, at the end of the clinical procedure, compared to GRMORF (systolic, diastolic and mean). Differences between groups were not observed for postoperative analgesia and degree of sedation. Epidural administration of ropivacaine is safe and effective and provides good analgesia regardless of its association with morphine or methadone.(AU)

Pseudo-Schell model sources.

Partially coherent pseudo-Schell model sources are introduced and analyzed. They present radial symmetry and coherence characteristics depending on the difference between the radial distances of two points from the source center. As a consequence, all points belonging to circles centered on the symmetry center of the source are perfectly correlated. We show that such sources radiate fields with peculiar behaviors in paraxial propagation. In particular, when compared to beams produced by Gaussian Schell-model sources with comparable coherence parameters, their irradiance can present sharper profiles and higher peak valuesmono and a better beam quality parameter. Furthermore, when a pseudo-Schell model source presents a vortex, the propagated beam preserves a null of the intensity along its axis.

Reliability and validity of the World Health Organization reading standards for paediatric chest radiographs used in the field in an impact study of Pneumococcal Conjugate Vaccine in Kilifi, Kenya.

BACKGROUND: Radiologically-confirmed pneumonia (RCP) is a specific end-point used in trials of Pneumococcal Conjugate Vaccine (PCV) to estimate vaccine efficacy. However, chest radiograph (CXR) interpretation varies within and between readers. We measured the repeatability and reliability of paediatric CXR interpretation using percent agreement and Cohen's Kappa and the validity of field readings against expert review in a study of the impact of PCV on pneumonia. METHODS: CXRs were obtained from 2716 children admitted between 2006 and 2014 to Kilifi County Hospital, Kilifi, Kenya, with clinically-defined severe or very-severe pneumonia. Five clinicians and radiologists attended a three-day training course on CXR interpretation using a WHO standard. All CXRs were read once by two local primary readers. Discordant readings and 13% of concordant readings were arbitrated by a panel of three expert radiologists. To assess repeatability, a 5% median random sample was presented twice. Sensitivity and specificity of the primary readers' interpretations was estimated against the 'gold-standard' of the arbitrators' results. RESULTS: Of 2716 CXRs, 2 were uninterpretable and 159 were evaluated twice. The percent agreement and Kappa for RCP were 89% and 0.68 and ranged between 84-97% and 0.19-0.68, respectively, for all pathological findings. Intra-observer repeatability was similar to inter-observer reliability. Sensitivities of the primary readers to detect RCP were 69% and 73%; specificities were 96% and 95%. CONCLUSION: Intra- and inter-observer agreements on interpretations of radiologically-confirmed pneumonia are fair to good. Reasonable sensitivity and high specificity make radiologically-confirmed pneumonia, determined in the field, a suitable measure of relative vaccine effectiveness.

Partially coherent sources with radial coherence.

Partially coherent sources with radial coherence are proposed. They present a circularly symmetric intensity profile and a degree of coherence whose absolute value only depends on the angular difference between the two considered points. In particular, the source is completely coherent at pairs of points belonging to the same radius. The modal structure of such sources is determined in the general case, and conditions are derived under which the field propagated in paraxial approximation remains radially coherent at any transverse plane. In such cases, the angular dependence of the correlation function is preserved upon propagation, although the intensity profile generally changes. An example of this kind of source has been experimentally synthesized by means of a simple setup, and its coherence characteristics have been tested by means of a Young interferometer.

Quality control of ultrasound for fetal biometry: results from the INTERGROWTH-21st Project.

OBJECTIVE: To assess a comprehensive package of ultrasound quality control in the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project, a large multicenter study of fetal growth. METHODS: Quality control (QC) measures were performed for 20 313 ultrasound scan images obtained prospectively from 4321 fetuses at 14-41 weeks' gestation in eight geographical locations. At the time of each ultrasound examination, three fetal biometric variables (head circumference (HC), abdominal circumference (AC) and femur length (FL)) were measured in triplicate on separately generated images. All measurements were taken in a blinded fashion. QC had two elements: (1) qualitative QC: visual assessment by sonographers at each study site of their images based on specific criteria, with 10% of images being re-assessed at the Oxford-based Ultrasound Quality Unit (compared using an adjusted kappa statistic); and (2) quantitative QC: assessment of measurement data by comparing the first, second and third measurements (intraobserver variability), remeasurement of caliper replacement in 10% (interobserver variability), both by Bland-Altman plots and plotting frequency histograms of the SD of triplicate measurements and assessing how many were above or below 2 SD of the expected distribution. The system allowed the sonographers' performances to be monitored regularly. RESULTS: A high level of agreement between self- and external scoring was demonstrated for all measurements (κ = 0.99 (95% CI, 0.98-0.99) for HC, 0.98 (95% CI, 0.97-0.99) for AC and 0.96 (95% CI, 0.95-0.98) for FL). Intraobserver 95% limits of agreement (LoA) of ultrasound measures for HC, AC and FL were ± 3.3%, ± 5.6% and ± 6.2%, respectively; the corresponding values for interobserver LoA were ± 4.4%, ± 6.0% and ± 5.6%. The SD distribution of triplicate measurements for all biometric variables showed excessive variability for three of 31 sonographers, allowing prompt identification and retraining. CONCLUSIONS: Qualitative and quantitative QC monitoring was feasible and highly reproducible in a large multicenter research study, which facilitated the production of high-quality ultrasound images. We recommend that the QC system we developed is implemented in future research studies and clinical practice. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Avaliação da dexmedetomidina e do tramadol, associados ao midazolam, em gatas anestesiadas com isoflurano e submetidas à ovário-histerectomia / Evaluation of dexmedetomidine and tramadol, associated with midazolam, in cats anesthetized with isoflurane, undergoing ovariohysterectomy

Objetivou-se comparar as alterações cardiorrespiratórias e a analgesia pós-operatória promovidas pela dexmedetomidina e pelo tramadol, quando associados ao midazolam, em felinas. Para tal, foram selecionadas 18 gatas hígidas, divididas em dois grupos randomizados: GDM, tratadas com dexmedetomidina (10µg/kg) e GTM, tratadas com tramadol (2mg/kg), ambos associados a midazolam (0,2mg/kg,) IM. Após 15 minutos, procedeu-se à indução anestésica com propofol (1,46±0,79mL), mantendo-se a anestesia com isoflurano. As felinas foram submetidas à ovário-histerectomia, registrando-se as variáveis cardiorrespiratórias 15 minutos após a MPA (M0), 15 minutos após a indução (M15) e sequencialmente a cada cinco minutos, até o término do procedimento cirúrgico (M20, M25, M30, M35 e M40). A avaliação da dor iniciou-se 30 minutos após o término do procedimento cirúrgico (MP30) e sequencialmente em intervalos de 30 minutos (MP60, MP90, MP120). A partir do MP120, as avaliações foram registradas a cada hora (MP180, MP240 e MP360). A associação dexmedetomidina-midazolam infere diminuição inicial de frequência cardíaca (FC) sem significado clínico e está relacionada à sedação mais pronunciada, à analgesia menor e menos duradoura e a episódios de êmese, quando comparada à associação tramadol-midazolam. Ambos os protocolos denotaram estabilidade cardiorrespiratória e podem ser considerados seguros em felinas submetidas à ovário-histectomia.(AU)

The aim of this study was to compare cardiorespiratory changes and post-operative analgesia provided by dexmedetomidine or tramadol, associated with midazolam, in female cats. For that purpose, 18 healthy cats were assigned to two randomized groups: GDM, which received dexmedetomidine (10 µg/kg) and GTM, which received tramadol (2 mg/kg), both associated with midazolam (0.2 mg/kg) IM. After 15 minutes, anesthesia was induced with propofol (1.46±0.79 mL) and maintained with isofluorane. Ovariohysterectomy was performed and cardiorespiratory variables were registered 15 minutes after pre-anesthetic medication (M0), 15 minutes after anesthetic induction (M15), and every five minutes until the end of the surgical procedure (M20, M25, M30, M35 e M40). Pain evaluation started 30 minutes after the surgery (MP30) and sequentially at thirty-minute intervals (MP60, MP90, MP120). After MP120, each evaluation was registered at every hour (MP180, MP240 e MP360). Dexmedetomidine-midazolam association results in decreases on initial heart rate (HR) without clinical relevance and it is related to pronounced sedation, poor and less durable antinociception and vomiting events, when compared to tramadol-midazolam association. Both protocols indicate cardiorespiratoy stability and safety in cats undergoing ovariohysterectomy.(AU)

Synthesis of circularly coherent sources.

An experiment is presented in which a partially coherent source endowed with circular coherence is generated. The source is synthesized through a time averaging procedure, so that the mutual intensity is used as the basic correlation function. The correlation between points at different radial distances from the source center is tested by means of a Young interferometer. To confirm the perfect coherence among points along a circle concentric with the source center, the Young mask is replaced by an array of equally spaced pinholes arranged along a circle. The observed pattern is identical to that produced by the same mask, illuminated by perfectly coherent light.

Partially coherent sources with circular coherence.

A new class of partially coherent light sources is introduced. At the source plane, they exhibit perfect coherence along any annulus that is concentric to the source center. Between two points at different distances from the center, coherence can be partial or even vanishing. Such sources can be synthesized by using a generalized form of van Cittert-Zernike theorem where axial sources are used. Beams radiated by this type of source are analyzed at the source plane and upon free propagation for some simple cases.

AMPK antagonizes hepatic glucagon-stimulated cyclic AMP signalling via phosphorylation-induced activation of cyclic nucleotide phosphodiesterase 4B.

Biguanides such as metformin have previously been shown to antagonize hepatic glucagon-stimulated cyclic AMP (cAMP) signalling independently of AMP-activated protein kinase (AMPK) via direct inhibition of adenylate cyclase by AMP. Here we show that incubation of hepatocytes with the small-molecule AMPK activator 991 decreases glucagon-stimulated cAMP accumulation, cAMP-dependent protein kinase (PKA) activity and downstream PKA target phosphorylation. Moreover, incubation of hepatocytes with 991 increases the Vmax of cyclic nucleotide phosphodiesterase 4B (PDE4B) without affecting intracellular adenine nucleotide concentrations. The effects of 991 to decrease glucagon-stimulated cAMP concentrations and activate PDE4B are lost in hepatocytes deleted for both catalytic subunits of AMPK. PDE4B is phosphorylated by AMPK at three sites, and by site-directed mutagenesis, Ser304 phosphorylation is important for activation. In conclusion, we provide a new mechanism by which AMPK antagonizes hepatic glucagon signalling via phosphorylation-induced PDE4B activation.