Publications by authors named "Ignacio Moreno"

103 Publications

Customized depolarization spatial patterns with dynamic retardance functions.

Sci Rep 2021 May 3;11(1):9415. Epub 2021 May 3.

Departamento de Física, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.

In this work we demonstrate customized depolarization spatial patterns by imaging a dynamical time-dependent pixelated retarder. A proof-of-concept of the proposed method is presented, where a liquid-crystal spatial light modulator is used as a spatial retarder that emulates a controlled spatially variant depolarizing sample by addressing a time-dependent phase pattern. We apply an imaging Mueller polarimetric system based on a polarization camera to verify the effective depolarization effect. Experimental validation is provided by temporal integration on the detection system. The effective depolarizance results are fully described within a simple graphical approach which agrees with standard Mueller matrix decomposition methods. The potential of the method is discussed by means of three practical cases, which include non-reported depolarization spatial patterns, including exotic structures as a spirally shaped depolarization pattern.
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http://dx.doi.org/10.1038/s41598-021-88515-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093234PMC
May 2021

Head adaptation for sound production and feeding strategy in dolphins (Odontoceti: Delphinida).

J Anat 2021 May 14;238(5):1070-1081. Epub 2020 Dec 14.

Marine Mammal Research, Department of Bioscience, Aarhus University, Roskilde, Denmark.

Head morphology in toothed whales evolved under selective pressures on feeding strategy and sound production. The postnatal development of the skull (n = 207) and mandible (n = 219) of six Delphinida species which differ in feeding strategy but exhibit similar sound emission patterns, including two narrow-band high-frequency species, were investigated through 3D morphometrics. Morphological changes throughout ontogeny were demonstrated based on the main source of variation (i.e., prediction lines) and the common allometric component. Multivariate trajectory analysis with pairwise comparisons between all species was performed to evaluate specific differences on the postnatal development of skulls and mandibles. Changes in the rostrum formation contributed to the variation (skull: 49%; mandible: 90%) of the entire data set and might not only reflect the feeding strategy adopted by each lineage but also represents an adaptation for sound production and reception. As an important structure for directionality of sound emissions, this may increase directionality in raptorial feeders. Phylogenetic generalized least squares analyses indicated that shape of the anterior portion of the skull is strongly dependent on phylogeny and might not only reflect feeding mode, but also morphological adaptations for sound production, particularly in raptorial species. Thus, postnatal development seems to represent a crucial stage for biosonar maturation in some raptorial species such as Pontoporia blainvillei and Sousa plumbea. The ontogeny of their main tool for navigation and hunting might reflect their natural history peculiarities and thus potentially define their main vulnerabilities to anthropogenic changes in the environment.
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http://dx.doi.org/10.1111/joa.13364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053589PMC
May 2021

In-phase sub-Nyquist lenslet arrays encoded onto spatial light modulators.

J Opt Soc Am A Opt Image Sci Vis 2020 Sep;37(9):1417-1422

When encoding diffractive lenses onto a spatial light modulator (SLM), there is a Nyquist limit to the smallest focal length that can be formed. When this limit is surpassed, a two-dimensional array of lenslets is formed. There have been very few discussions on the performance of these lenslets. In this work, we focus on the phase distribution of these lenses in the array. We show that, for certain values of the focal length, the lenslets are all in perfect phase. We show that this situation happens for a total number of /4 different discrete equidistant sub-Nyquist focal lengths, where × is the number of pixels in the SLM. We find other distances in between where the array is composed of two sets of lenslets with a relative phase among them. Finally, we illustrate these phase distributions in the application to generate an array of vortex producing lenses. We expect that these results might be useful for high-accuracy interferometric or multiple imaging where this phase must be exactly the same for each replica.
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http://dx.doi.org/10.1364/JOSAA.398828DOI Listing
September 2020

Measuring the spatial deformation of a liquid-crystal on silicon display with a self-interference effect.

Opt Lett 2020 Aug;45(16):4480-4483

We present a simple technique to characterize the spatial non-uniformity of a liquid-crystal on silicon (LCOS) spatial light modulator (SLM). It is based on illuminating the display with a wavelength out of the operation range, so there is a significant reflection at the output surface. As a consequence, a Gires-Tournois interferometer is directly created, without any alignment requirement and insensitive to vibrations. The beam reflected at the output surface is the reference beam, while the beam reflected at the silicon backplane is modulated with the addressed gray level in order to quantitatively derive its deformation. We provide an experimental demonstration using a LCOS-SLM designed to operate in the near-infrared range but illuminated with visible light.
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http://dx.doi.org/10.1364/OL.396105DOI Listing
August 2020

Heterogeneity in the linear shiny white structures in melanomas seen with polarized light according to histopathological association: Cross-sectional observational study in 118 cutaneous melanomas.

J Dermatol 2020 Sep 14;47(9):1058-1062. Epub 2020 Jun 14.

Dermatology Department, Hospital Sant Pau i Santa Tecla, Tarragona, Spain.

Polarized dermoscopy enables visualization of linear shiny white structures in melanomas, thought to be due to the existence of fibrosis in the dermis. Our objective was to establish the existence of two types of linear shiny white structures and assess their association with different histological structures. We performed a cross-sectional study including all non-acral, non-facial melanomas from our hospital with linear shiny white structures. The outcome variable was the type of linear shiny white structures: shiny white streaks and white strands. We evaluated their association with explanatory variables that may affect the reflectance of melanomas and Breslow index. We used χ statistics and also calculated the sensitivity and specificity of each linear shiny white structure to predict those variables. We detected linear shiny white structures in 118 melanomas. Regarding shiny white streaks, we only found a statistically significant positive relationship with fibrosis in the papillary dermis. Regarding white strands, we found statistically significant and positive relationships with hyperkeratosis, Breslow index of 0.8 mm or more and acanthosis. Sensitivity and specificity study revealed that the presence of shiny white streaks was the most sensitive (81.7%) and specific (72.3%) for fibrosis in the papillary dermis, and presence of white strands was the most sensitive (91.1%) and specific (85.7%) for hyperkeratosis.
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http://dx.doi.org/10.1111/1346-8138.15457DOI Listing
September 2020

Skull morphology of bottlenose dolphins from different ocean populations with emphasis on South America.

J Morphol 2020 06 6;281(6):564-577. Epub 2020 Apr 6.

Universidade do Vale do Itajaí, Laboratório de Informática da Biodiversidade e Geomática, Itajaí, SC, Brazil.

The bottlenose dolphin, genus Tursiops, is cosmopolitan occurring in tropical and temperate regions, with morphological variation between and within different oceans. Since the genus' taxonomy has been under discussion for a long time, this work aimed at analyzing the cranial variability of T. truncatus from different regions of the world. Geometric Morphometrics analyses were performed in 201 skulls of adult specimens, on dorsal, ventral, and lateral views, from the Eastern North Pacific, Eastern North Atlantic, Eastern South Atlantic, and Western South Atlantic oceans. The results indicate differences between individuals that inhabit the Atlantic and Pacific oceans. Within the Atlantic Ocean, there is an evident longitudinal differentiation of specimens from the eastern and western regions. A latitudinal separation was also observed, considering specimens from the North and South Atlantic Ocean. In the Western South Atlantic statistical differences were found between two morphological groups, identified as T. gephyreus (sensu Lahille, 1908) and T. truncatus, and the cross-validation presented 98% as minimum confidence for correct classification of these two groups. The present study provides strong morphological support to consider these two lineages as separate species.
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http://dx.doi.org/10.1002/jmor.21121DOI Listing
June 2020

Ccm1p is a 15S rRNA primary transcript processing factor as elucidated by a novel in vivo system in Saccharomyces cerevisiae.

Curr Genet 2020 Aug 9;66(4):775-789. Epub 2020 Mar 9.

Department of Biological Sciences, Alcorn State University, 1000 ASU Drive # 870, Lorman, MS, 39096, USA.

In Saccharomyces cerevisiae, the mitoribosomal RNA of the minor subunit, 15S rRNA, is transcribed as a bicistronic transcript along with tRNA. 5' and 3' sequences flanking the mature transcript must be removed by cleavage at the respective junctions before incorporating it into the mitoribosome. An in vivo dose-response triphasic system was created to elucidate the role of Ccm1p in the processing of 15S rRNA: Ccm1p supply ("On"), deprivation ("Off"), and resupply ("Back on"). After 72 h under "Off" status, the cells started to exhibit a complete mutant phenotype as assessed by their lack of growth in glycerol medium, while keeping their mitochondrial DNA integrity (ρ). Full functionality of mitochondria was reacquired upon "Back on." 15S rRNA levels and phenotype followed the Ccm1p intramitochondrial concentrations throughout the "On-Off-Back on" course. Under "Off" status, cells gradually accumulated unprocessed 5' and 3' junctions, which reached significant levels at 72-96 h, probably due to a saturation of the mitochondrial degradosome (mtEXO). The Ccm1p/mtEXO mutant (Δccm1/Δdss1) showed a copious accumulation of 15S rRNA primary transcript forms, which were cleaved upon Ccm1p resupply. The gene that codes for the RNA component of RNase P was conserved in wild-type and mutant strains. Our results indicate that Ccm1p is crucial in processing the 15S rRNA primary transcript and does not stabilize the already mature 15S rRNA. Consequently, failure of this function in Δccm1 cells results, as it happens to any other unprocessed primary transcripts, in total degradation of 15S rRNA by mtEXO, whose mechanism of action is discussed.
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http://dx.doi.org/10.1007/s00294-020-01064-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7367710PMC
August 2020

Quantitative Transthoracic Echocardiography of the Response to Dobutamine in Cardiac Surgery Patients With Low Cardiac Output Syndrome.

J Cardiothorac Vasc Anesth 2020 Jan 16;34(1):87-96. Epub 2019 Aug 16.

Hospital Universitari i Politecnic La Fe, Valencia, Spain; Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain. Electronic address:

Objective: To quantify the acute effects of dobutamine in postoperative low cardiac output syndrome (LCOS) using transthoracic echocardiographic, hemodynamic, and blood biomarker monitoring and to assess its association with clinical outcomes.

Design: Observational prospective study.

Setting: Single university hospital.

Participants: Patients undergoing elective cardiac surgery.

Interventions: None.

Measurements And Main Results: Echocardiographic parameters, hemodynamic data, and plasma biomarkers were obtained before and early after inotrope initiation. The diagnostic value of transthoracic echocardiographic parameters and their association with clinical outcome were evaluated. Thirty-eight LCOS patients and 12 control patients were included. The left ventricular outflow tract velocity time integral was significantly lower in LCOS patients (11.75 v 19.08 cm; p < 0.001) and showed a marked improvement after dobutamine administration (∼37% increase). Dobutamine improved left and right ventricular function, increased mean arterial pressure and urine output, and lowered lactate levels. The duration of dobutamine support, but not in-hospital mortality, was associated with echocardiographic estimates of cardiac performance early after dobutamine initiation.

Conclusions: Early transthoracic echocardiographic assessment and the acute response to inotropic therapy may provide rapid and highly valuable information in the diagnostic workup and risk evaluation of patients with suspected LCOS after cardiac surgery.
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http://dx.doi.org/10.1053/j.jvca.2019.08.019DOI Listing
January 2020

Encoding lenses with focal lengths lower than the Nyquist limit using high phase-modulation displays.

Opt Lett 2019 Jul;44(13):3398-3401

Liquid crystal displays allow the easy implementation of diffractive optical elements. However, the shortest focal lengths for lenses are limited by Nyquist conditions. In this work, we show that focal lengths much lower than this Nyquist limit can be encoded onto devices having a large phase-dynamic range. Experimental results are included with a display showing 10π phase modulation reducing the Nyquist limit by a factor of about 1/10.
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http://dx.doi.org/10.1364/OL.44.003398DOI Listing
July 2019

Optimal triplicator design applied to a geometric phase vortex grating.

Opt Express 2019 May;27(10):14472-14486

In this work, a geometric phase liquid-crystal diffraction grating based on the optimal triplicator design is realized, i.e., a phase-only profile that generates three diffraction orders with equal intensity and maximum diffraction efficiency. We analyze the polarization properties of this special diffraction grating and then use embedded spiral phases to design geometric phase vortex diffraction gratings. Finally, the fabrication of a two-dimensional version of such a design using a micro-patterned half-wave retarder is demonstrated, where the phase distribution is encoded as the orientation of the fast axis of the retarder. This proof-of-concept element is made of liquid crystal on BK7 substrate where the orientation of the LC is controlled via photoalignment, using a commercially available fabrication facility. Experimental results demonstrate the parallel generation of vortex beams with different topological charge and different states of polarization.
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http://dx.doi.org/10.1364/OE.27.014472DOI Listing
May 2019

Simultaneous aberration and aperture control using a single spatial light modulator.

Opt Express 2019 Apr;27(9):12399-12413

A method to simultaneously control aberrations and the aperture of an optical system using a single phase-only spatial light modulator was investigated. The experiment was performed using a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) within an adaptive optics system used for visual testing, although the method has broader applications in adaptive optics field. The performance of the technique was characterized through the estimation of the system's modulation transfer functions (MTFs) by using a random chart method. MTFs obtained from the phase modulation-based approach were compared with those from using a real aperture (diaphragm). The areas under the MTFs for the two conditions were similar up to 98%, confirming that the low-pass filter effect associated to the size of the entrance pupil was similar for the phase-modulated pupil and the physical pupil. As an example of application, both aberrations and pupil were controlled by a single phase-only modulator to study the through-focus visual performance in real subjects. Limitations and possible enhancements of the presented method were also discussed. The presented technique reduces complexity and cost of adaptive optics systems. It opens the door to new experiments by allowing dynamic modulation of aberrations and apertures of any shape.
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http://dx.doi.org/10.1364/OE.27.012399DOI Listing
April 2019

Gouy phase effects on propagation of pure and hybrid vector beams.

Opt Express 2019 Feb;27(3):2374-2386

The robustness of the polarization spatial distribution of vector beams upon propagation is crucial for a number of applications, including optical communications and materials processing. This study has been commonly centered on Gouy phase effects on focused vector beams. In this work, we present a theoretical and experimental analysis of the Gouy phase's effects on the propagation of pure and hybrid vector beams. Experimental results at various axial planes, before and past the focus, are obtained by using a simplified liquid-crystal spatial light modulator-based optical system that allows the easy generation of these beams. Furthermore, a new alternative optical set-up that is devoid of moving elements is demonstrated, which simplifies this study. We experimentally verify the differences between pure and hybrid vector beams upon propagation. While the first ones remain stable, hybrid vector beams show Gouy phase effects that demonstrate an optical activity where the local polarization states rotate by an angle that depends on the propagation distance. Experimental results agree with the theory.
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http://dx.doi.org/10.1364/OE.27.002374DOI Listing
February 2019

From the Pharynx to the Abdomen: A Case of Primary Peritonitis.

Acta Med Port 2018 Dec 28;31(12):774-777. Epub 2018 Dec 28.

Serviço de Medicina Intensiva 1. Centro Hospitalar Universitário do Algarve. Unidade de Faro. Faro. Portugal.

Primary peritonitis usually occurs in patients with comorbidities previously diagnosed with ascites. However, a primary peritoneal infection in previously healthy patients may also ensue. There has been an increase in reported cases of primary peritonitis due to Streptococcus pyogenes affecting mostly women. It usually presents as a severe acute abdominal pain, which prompts surgical exploration. Although infected ascitic fluid is seen, there is no rupture. In this article, we present a case of primary peritonitis due to Streptococcus pyogenes which rapidly evolved to septic shock and acute respiratory distress syndrome. The abdominal and pelvic computed tomography at admission showed no ascitic fluid. However, a few hours later, during surgical exploration, purulent ascitic fluid was seen throughout the abdominal cavity. It is important to be aware of this rapid accumulation of ascitic fluid, even without visceral perforation, as peritoneal lavage may be warranted to contain the infection.
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http://dx.doi.org/10.20344/amp.10053DOI Listing
December 2018

Sound Generating Structures of the Humpback Dolphin Sousa plumbea (Cuvier, 1829) and the Directionality in Dolphin Sounds.

Anat Rec (Hoboken) 2019 06 13;302(6):849-860. Epub 2018 Nov 13.

Department II of Anatomy, University of Cologne, 50924, Cologne, Germany.

The macroscopic morphology of structures involved in sound generation in the Indian Ocean humpback dolphin (Sousa plumbea) were described for the first time using computed tomography imaging and standard gross dissection techniques. The Indian Ocean humpback dolphin may represent a useful comparative model to the bottlenose dolphin (Tursiops sp.) to provide insights into the functional anatomy of the sound production in dolphins, since these coastal dolphins exhibit similar body size and share similarities on acoustic behavior. The general arrangement of sound generating structures, that is, air sacs and muscles, was similar in both the bottlenose dolphin and the Indian Ocean humpback dolphin. The main difference between the two species existed in a small left posterior branch of the melon in the Indian Ocean humpback dolphin, which was not found in the bottlenose dolphin and might reflect an adaptation of directionality for high frequency communication sounds as seen in some other delphinids (e.g., Lagenorhynchus sp., Grampus griseus). Thus, this may be the main reason for the asymmetry of the sound production structures in dolphins. Additionally, the longer rostrum in Indian Ocean humpback dolphins might suggest a more directional echolocation beam compared to the Lahille's bottlenose dolphin. Anat Rec, 302:849-860, 2019. © 2018 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ar.23981DOI Listing
June 2019

Achromatic linear retarder with tunable retardance.

Opt Lett 2018 Jul;43(14):3277-3280

We present a universal design and proof-of-concept of a tunable linear retarder of uniform wavelength response in a broad spectral range. It consists of two half-wave retarders (HWR) between two quarter-wave retarders (QWRs), where the uniform retardance can be tuned continuously by simply rotating one of the HWRs. A proof-of-concept of this design is built by using commercially available Fresnel rhomb retarders that provide retardation with almost wavelength uniformity in the visible and near infrared from 450 to 1550 nm. The design is universal, since other achromatic QWRs and HWRs could also be employed. The system is experimentally demonstrated to control the state of polarization of a supercontinuum laser.
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http://dx.doi.org/10.1364/OL.43.003277DOI Listing
July 2018

Hereditary breast and ovarian cancer in Andalusian families: a genetic population study.

BMC Cancer 2018 Jun 8;18(1):647. Epub 2018 Jun 8.

Clinical Oncology Unit Hospitales Universitarios Regional y Virgen de la Victoria. Instituto de Investigación Biomédica de Málaga (IBIMA), Campus Teatinos s/n. 29010, Malaga, Spain.

Background: The BRCA1/2 mutation profile varies in Spain according to the geographical area studied. The mutational profile of BRCA1/2 in families at risk for hereditary breast and ovarian cancer has not so far been reported in Andalusia (southern Spain).

Methods: We analysed BRCA1/2 germline mutations in 562 high-risk cases with breast and/or ovarian cancer from Andalusian families from 2010 to 2015.

Results: Among the 562 cases, 120 (21.4%) carried a germline pathogenic mutation in BRCA1/2; 50 in BRCA1 (41.7%) and 70 in BRCA2 (58.3%). We detected 67 distinct mutations (29 in BRCA1 and 38 in BRCA2), of which 3 in BRCA1 (c.845C > A, c.1222_1223delAC, c.2527delA) and 5 in BRCA2 (c.293 T > G, c.5558_5559delGT, c.6034delT, c.6650_6654delAAGAT, c.6652delG) had not been previously described. The most frequent mutations in BRCA1 were c.5078_5080delCTG (10%) and c.5123C > A (10%), and in BRCA2 they were c.9018C > A (14%) and c.5720_5723delCTCT (8%). We identified 5 variants of unknown significance (VUS), all in BRCA2 (c.5836 T > C, c.6323G > T, c.9501 + 3A > T, c.8022_8030delGATAATGGA, c.10186A > C). We detected 76 polymorphisms (31 in BRCA1, 45 in BRCA2) not associated with breast cancer risk.

Conclusions: This is the first study reporting the mutational profile of BRCA1/2 in Andalusia. We identified 21.4% of patients harbouring BRCA1/2 mutations, 58.3% of them in BRCA2. We also characterized the clinical data, mutational profile, VUS and haplotype profile.
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http://dx.doi.org/10.1186/s12885-018-4537-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994127PMC
June 2018

A giant hepatocellular carcinoma with uncommon features.

Intern Emerg Med 2018 Oct 15;13(7):1129-1130. Epub 2018 May 15.

Emergency Department, Hospital de Faro, Centro Hospitalar Universitário do Algarve, Rua Leão Penedo, 8000-386, Faro, Portugal.

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http://dx.doi.org/10.1007/s11739-018-1875-1DOI Listing
October 2018

Random technique to encode complex valued holograms with on axis reconstruction onto phase-only displays.

Opt Express 2018 Mar;26(5):5875-5893

A new technique for encoding the amplitude and phase of diffracted fields in digital holography is proposed. It is based on a random spatial multiplexing of two phase-only diffractive patterns. The first one is the phase information of the intended pattern, while the second one is a diverging optical element whose purpose is the control of the amplitude. A random number determines the choice between these two diffractive patterns at each pixel, and the amplitude information of the desired field governs its discrimination threshold. This proposed technique is computationally fast and does not require iterative methods, and the complex field reconstruction appears on axis. We experimentally demonstrate this new encoding technique with holograms implemented onto a flicker-free phase-only spatial light modulator (SLM), which allows the axial generation of such holograms. The experimental verification includes the phase measurement of generated patterns with a phase-shifting polarization interferometer implemented in the same experimental setup.
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http://dx.doi.org/10.1364/OE.26.005875DOI Listing
March 2018

Q-plates with a nonlinear azimuthal distribution of the principal axis: application to encoding binary data.

Appl Opt 2018 Feb;57(5):1005-1010

We encode q-plates where the angular orientation of the principal axis is varied spatially with a nonstandard distribution. In the usual q-plate design, the orientation of the optical axis depends linearly on the azimuthal angle. In this work, we examine cases where this azimuthal dependence is nonlinear. We consider two cases: first, where the principal axis distribution is like an inverse-tangent function of the azimuth; and second, where it displays linear and flat segments. This last case is proposed as a new method for encoding binary data into the azimuthal lobes of the vector beam. We encode these patterns using a spatial light modulator system that allows new and exotic q-plate designs without the difficulty of fabricating individual plates. Experimental results are presented.
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http://dx.doi.org/10.1364/AO.57.001005DOI Listing
February 2018

Acute Inflammation and Metabolism.

Inflammation 2018 Aug;41(4):1115-1127

Internal Medicine 1, Hospital de Faro, Centro Hospitalar Universitário do Algarve, Rua Leão Penedo, Faro, 8000-386, Portugal.

Inflammation is an adaptive process to the noxious stimuli that the human body is constantly exposed to. From the local inflammatory response to a full-blown systemic inflammation, a wide complex sequence of events occurs. Persistent immunosuppression and catabolism may ensue, until multiple organ failure finally sets in. And since clinically useful and specific biomarkers are lacking, diagnosis may come late. A thorough understanding of these events (how they begin, how they evolve, and how to modulate them) is imperative, but as yet poorly studied. This review aims to consolidate current knowledge of these events so that the management of these patients is not only evidence-based, but also built on an understanding of the inner workings of the human body in health and in disease.
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http://dx.doi.org/10.1007/s10753-018-0739-1DOI Listing
August 2018

Dual polarization split lenses.

Opt Express 2017 Oct;25(20):23773-23783

We report the realization of polarization sensitive split lens configurations. While split lenses can be used to easily generate different types of controlled structured light patterns, their realization has been limited so far to scalar beams. Here we propose and experimentally demonstrate their generalization to vectorial split lenses, leading to light patterns with customized intensity and state of polarization. We demonstrate how these polarization split lenses can be experimentally implemented by means of an optical system using two liquid crystal spatial light modulators, each one phase modulating one orthogonal polarization component. As a result, we demonstrate the experimental generation of vectorial beams with different shapes generated with these dual polarization split lenses. Excellent experimental results are provided in each case. The proposed technique is a simple method to generate structured light beams with polarization diversity, with potential applications in polarimetry, customized illuminators or quantum optics.
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http://dx.doi.org/10.1364/OE.25.023773DOI Listing
October 2017

Polarimetric imaging of biological tissues based on the indices of polarimetric purity.

J Biophotonics 2018 04 12;11(4):e201700189. Epub 2017 Dec 12.

Grup d'Òptica, Physics Department, Universitat Autònoma de Barcelona, Bellaterra, Spain.

We highlight the interest of using the indices of polarimetric purity (IPPs) to the inspection of biological tissues. The IPPs were recently proposed in the literature and they result in a further synthetization of the depolarizing properties of samples. Compared with standard polarimetric images of biological samples, IPP-based images lead to larger image contrast of some biological structures and to a further physical interpretation of the depolarizing mechanisms inherent to the samples. In addition, unlike other methods, their calculation do not require advanced algebraic operations (as is the case of polar decompositions), and they result in 3 indicators of easy implementation. We also propose a pseudo-colored encoding of the IPP information that leads to an improved visualization of samples. This last technique opens the possibility of tailored adjustment of tissues contrast by using customized pseudo-colored images. The potential of the IPP approach is experimentally highlighted along the manuscript by studying 3 different ex-vivo samples. A significant image contrast enhancement is obtained by using the IPP-based methods, compared to standard polarimetric images.
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http://dx.doi.org/10.1002/jbio.201700189DOI Listing
April 2018

Vector Beam Polarization State Spectrum Analyzer.

Sci Rep 2017 05 22;7(1):2216. Epub 2017 May 22.

Department of Physics, San Diego State University, California, 92182-1233, USA.

We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from -3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.
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http://dx.doi.org/10.1038/s41598-017-02328-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440383PMC
May 2017

Polarization gating based on Mueller matrices.

J Biomed Opt 2017 05;22(5):56004

Universitat Autònoma de Barcelona, Grup d'Òptica, Physics Department, Bellaterra, Spain.

We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. In particular, we show how using the measured Mueller matrix (MM) of a sample, a widespread number of PG configurations can be evaluated just from analytical expressions based on the MM coefficients. We also show the interest of controlling the helicity of the states of polarization used for PG-based metrology, as this parameter has an impact in the image contrast of samples. In addition, we highlight the interest of combining PG techniques with tools of data analysis related to the MM formalism, such as the well-known MM decompositions. The method discussed in this work is illustrated with the results of polarimetric measurements done on artificial phantoms and real ex-vivo tissues.
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http://dx.doi.org/10.1117/1.JBO.22.5.056004DOI Listing
May 2017

Arithmetic with q-plates.

Appl Opt 2017 Jan;56(3):596-600

In this work we show the capability to form various q-plate equivalent systems using combinations of commercially available q-plates. We show operations like changing the sign of the q-value, or the addition and subtraction of q-plates. These operations only require simple combinations of q-plates and half-wave plates. Experimental results are presented in all cases. Following this procedure, experimental testing of higher and negative q-valued devices can be carried out using commonly available q-valued devices.
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http://dx.doi.org/10.1364/AO.56.000596DOI Listing
January 2017

PIN6 auxin transporter at endoplasmic reticulum and plasma membrane mediates auxin homeostasis and organogenesis in Arabidopsis.

New Phytol 2016 07;211(1):65-74

Institute of Science and Technology Austria (IST Austria), 3400, Klosterneuburg, Austria.

Plant development mediated by the phytohormone auxin depends on tightly controlled cellular auxin levels at its target tissue that are largely established by intercellular and intracellular auxin transport mediated by PIN auxin transporters. Among the eight members of the Arabidopsis PIN family, PIN6 is the least characterized candidate. In this study we generated functional, fluorescent protein-tagged PIN6 proteins and performed comprehensive analysis of their subcellular localization and also performed a detailed functional characterization of PIN6 and its developmental roles. The localization study of PIN6 revealed a dual localization at the plasma membrane (PM) and endoplasmic reticulum (ER). Transport and metabolic profiling assays in cultured cells and Arabidopsis strongly suggest that PIN6 mediates both auxin transport across the PM and intracellular auxin homeostasis, including the regulation of free auxin and auxin conjugates levels. As evidenced by the loss- and gain-of-function analysis, the complex function of PIN6 in auxin transport and homeostasis is required for auxin distribution during lateral and adventitious root organogenesis and for progression of these developmental processes. These results illustrate a unique position of PIN6 within the family of PIN auxin transporters and further add complexity to the developmentally crucial process of auxin transport.
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http://dx.doi.org/10.1111/nph.14019DOI Listing
July 2016

Nondiffracting vector beams where the charge and the polarization state vary with propagation distance.

Opt Lett 2016 May;41(10):2270-3

We generate nondiffracting vector beams where the charge and the polarization state vary with the propagation distance. We use reflective geometry where a parallel-aligned spatial light modulator is used to spatially modulate two orthogonal linear polarizations. We encode spiral phases with equal charge but with opposite signs onto the two polarization directions to encode a vector beam and add two axicon phases. Both the charge and the phase shift between the two axicons can be varied along the focus line. We provide experimental results that demonstrate both features.
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http://dx.doi.org/10.1364/OL.41.002270DOI Listing
May 2016

Generation of integer and fractional vector beams with q-plates encoded onto a spatial light modulator.

Opt Lett 2016 Mar;41(6):1305-8

We generate programmable vector beams with arbitrary q-plates encoded using a spatial light modulator system. Consequently, we can analyze new and exotic q-plate designs without the difficulty of fabricating individual plates. We show experimental results for positive and negative integer and new fractional vector beam values.
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http://dx.doi.org/10.1364/OL.41.001305DOI Listing
March 2016

Population Genetic Structure of the Magnificent Frigatebird Fregata magnificens (Aves, Suliformes) Breeding Colonies in the Western Atlantic Ocean.

PLoS One 2016 22;11(2):e0149834. Epub 2016 Feb 22.

Departament of Genetics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.

The Magnificent Frigatebird Fregata magnificens has a pantropical distribution, nesting on islands along the Atlantic and Pacific coasts. In the Caribbean, there is little genetic structure among colonies; however, the genetic structure among the colonies off Brazil and its relationship with those in the Caribbean are unknown. In this study, we used mtDNA and microsatellite markers to infer population structure and evolutionary history in a sample of F. magnificens individuals collected in Brazil, Grand Connétable (French Guyana), and Barbuda. Virtually all Brazilian individuals had the same mtDNA haplotype. There was no haplotype sharing between Brazil and the Caribbean, though Grand Connétable shared haplotypes with both regions. A Bayesian clustering analysis using microsatellite data found two genetic clusters: one associated with Barbuda and the other with the Brazilian populations. Grand Connétable was more similar to Barbuda but had ancestry from both clusters, corroborating its "intermediate" position. The Caribbean and Grand Connétable populations showed higher genetic diversity and effective population size compared to the Brazilian population. Overall, our results are in good agreement with an effect of marine winds in isolating the Brazilian meta-population.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0149834PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4762693PMC
July 2016

Diffraction gratings generating orders with selective states of polarization.

Opt Express 2016 Jan;24(2):907-17

We propose specially designed double anisotropic polarization diffraction gratings capable of producing a selective number of diffraction orders and with selective different states of polarization. Different polarization diffraction gratings are demonstrated, including linear polarization with horizontal, vertical and ± 45° orientations, and circular R and L polarization outputs. When illuminated with an arbitrary state of polarization, the system acts as a complete polarimeter where the intensities of the diffraction orders allow measurement of the Stokes parameters with a single shot. Experimental proof-of-concept is presented using a parallel-aligned liquid crystal display operating in a double pass architecture.
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http://dx.doi.org/10.1364/OE.24.000907DOI Listing
January 2016