The southwesternmost record of late Silurian (Pridolian) early land plants of Gondwana.

The Silurian-Devonian transition played a crucial role in the development of early terrestrial ecosystems due to the rapid diversification of early vascular plants. However, records of Pridolian plants in western Gondwana are scarce, limited to outcrops located in southern Bolivia. In this contribution, an association of fossil plants housed in the Rinconada Formation is presented.

PoLambRimetry: a multispectral polarimetric atlas of lamb brain.

Significance: Mueller matrix imaging (MMI) is a comprehensive form of polarization imaging useful for assessing structural changes. However, there is limited literature on the polarimetric properties of brain specimens, especially with multispectral analysis.

Aim: We aim to employ multispectral MMI for an exhaustive polarimetric analysis of brain structures, providing a reference dataset for future studies and enhancing the understanding of brain anatomy for clinicians and researchers.

Role of Topical Tranexamic Acid on Blood Loss and Transfusion Requirements in Spinal Fusion for Neuromuscular and Syndromic Scoliosis.

Study Design: Retrospective case control study.

Objectives: To determine the role of TXA when used as topical soaked sponges (tTXA) on peri-operative blood loss and changes in hemoglobin following posterior spinal fusion (PSF) for neuromuscular and syndromic scoliosis (NMS).

Methods: A single center review of NMS patients who underwent PSF was conducted.

Melanoma and Nevi Subtype Histopathological Characterization with Optical Coherence Tomography.

Background: Melanoma incidence has continued to rise in the latest decades, and the forecast is not optimistic. Non-invasive diagnostic imaging techniques such as optical coherence tomography (OCT) are largely studied; however, there is still no agreement on its use for the diagnosis of melanoma. For dermatologists, the differentiation of non-invasive (junctional nevus, compound nevus, intradermal nevus, and melanoma in-situ) versus invasive (superficial spreading melanoma and nodular melanoma) lesions is the key issue in their daily routine.

Modeling and Synthesis of Breast Cancer Optical Property Signatures With Generative Models.

Is it possible to find deterministic relationships between optical measurements and pathophysiology in an unsupervised manner and based on data alone? Optical property quantification is a rapidly growing biomedical imaging technique for characterizing biological tissues that shows promise in a range of clinical applications, such as intraoperative breast-conserving surgery margin assessment. However, translating tissue optical properties to clinical pathology information is still a cumbersome problem due to, amongst other things, inter- and intrapatient variability, calibration, and ultimately the nonlinear behavior of light in turbid media. These challenges limit the ability of standard statistical methods to generate a simple model of pathology, requiring more advanced algorithms.

Context-free hyperspectral image enhancement for wide-field optical biomarker visualization.

Many well-known algorithms for the color enhancement of hyperspectral measurements in biomedical imaging are based on statistical assumptions that vary greatly with respect to the proportions of different pixels that appear in a given image, and thus may thwart their application in a surgical environment. This article attempts to explain why this occurs with SVD-based enhancement methods, and proposes the separation of spectral enhancement from analysis. The resulting method, termed , or ACE for short, achieves multi- and hyperspectral image coloring and contrast based on current spectral affinity metrics that can physically relate spectral data to a particular biomarker.

Morphological, optical and photovoltaic characteristics of MoSe/SiO/Si heterojunctions.

This work reports the effect of different processing parameters on the structural and morphological characteristics of MoSe layers grown by chemical vapour deposition (CVD), using MoO and Se powders as solid precursors. It shows the strong dependence of the size, shape and thickness of the MoSe layers on the processing parameters. The morphology of the samples was investigated by field emission scanning electron microscopy (FESEM) and the thickness of the deposited layers was determined by atomic force microscopy (AFM).

On the spectral signature of melanoma: a non-parametric classification framework for cancer detection in hyperspectral imaging of melanocytic lesions.

Early detection and diagnosis is a must in secondary prevention of melanoma and other cancerous lesions of the skin. In this work, we present an online, reservoir-based, non-parametric estimation and classification model that allows for this functionality on pigmented lesions, such that detection thresholding can be tuned to maximize accuracy and/or minimize overall false negative rates. This system has been tested in a dataset consisting of 116 patients and a total of 124 hyperspectral images of nevi, raised nevi and melanomas, detecting up to 100% of the suspicious lesions at the expense of some false positives.

Custom Scanning Hyperspectral Imaging System for Biomedical Applications: Modeling, Benchmarking, and Specifications.

Prototyping hyperspectral imaging devices in current biomedical optics research requires taking into consideration various issues regarding optics, imaging, and instrumentation. In summary, an ideal imaging system should only be limited by exposure time, but there will be technological limitations (e.g.

Identification of Human Pathological Mitral Chordae Tendineae Using Polarization-sensitive Optical Coherence Tomography.

Defects of the mitral valve complex imply heart malfunction. The chordae tendineae (CTs) are tendinous strands connecting the mitral and tricuspid valve leaflets to the papillary muscles. These CTs are composed of organized, wavy collagen bundles, making them a strongly birefringent material.

Directional Kernel Density Estimation for Classification of Breast Tissue Spectra.

In Breast Conserving Therapy, surgeons measure the thickness of healthy tissue surrounding an excised tumor (surgical margin) via post-operative histological or visual assessment tests that, for lack of enough standardization and reliability, have recurrence rates in the order of 33%. Spectroscopic interrogation of these margins is possible during surgery, but algorithms are needed for parametric or dimension reduction processing. One methodology for tumor discrimination based on dimensionality reduction and nonparametric estimation-in particular, Directional Kernel Density Estimation-is proposed and tested on spectral image data from breast samples.

Hessian analysis for the delineation of amorphous anomalies in optical coherence tomography images of the aortic wall.

The aortic aneurysm is a disease originated mainly in the media layer of the aortic wall due to the occurrence of degraded areas of altered biological composition. These anomalous regions affect the structure and strength of the aorta artery, being their occurrence and extension proportional to the arterial vessel health. Optical Coherence Tomography (OCT) is applied to obtain cross-sectional images of the artery wall.

Identification of vessel wall degradation in ascending thoracic aortic aneurysms with OCT.

Degradation of the wall of human ascending thoracic aorta has been assessed through Optical Coherence Tomography (OCT). OCT images of the media layer of the aortic wall exhibit micro-structure degradation in case of diseased aortas from aneurysmal vessels. The OCT indicator of degradation depends on the dimension of areas of the media layer where backscattered reflectivity becomes smaller due to a disorder on the morphology of elastin, collagen and smooth muscle cells (SMCs).

Optical coherence tomography assessment of vessel wall degradation in thoracic aortic aneurysms.

Optical coherence tomography images of human thoracic aorta from aneurysms reveal elastin disorders and smooth muscle cell alterations when visualizing the media layer of the aortic wall. These disorders can be employed as indicators for wall degradation and, therefore, become a hallmark for diagnosis of risk of aneurysm under intraoperative conditions. Two approaches are followed to evaluate this risk: the analysis of the reflectivity decay along the penetration depth and the textural analysis of a two-dimensional spatial distribution of the aortic wall backscattering.

Direct identification of breast cancer pathologies using blind separation of label-free localized reflectance measurements.

Breast tumors are blindly identified using Principal (PCA) and Independent Component Analysis (ICA) of localized reflectance measurements. No assumption of a particular theoretical model for the reflectance needs to be made, while the resulting features are proven to have discriminative power of breast pathologies. Normal, benign and malignant breast tissue types in lumpectomy specimens were imaged ex vivo and a surgeon-guided calibration of the system is proposed to overcome the limitations of the blind analysis.

Influence of annealing conditions on the formation of regular lattices of voids and Ge quantum dots in an amorphous alumina matrix.

In this work, the influence of air pressure during the annealing of Ge quantum dot (QD) lattices embedded in an amorphous Al(2)O(3) matrix on the structural, morphological and compositional properties of the film is studied. The formation of a regularly ordered void lattice after performing a thermal annealing process is explored. Our results show that both the Ge desorption from the film and the regular ordering of the QDs are very sensitive to the annealing parameters.

Characterization of poly(2-hydroxyethyl methacrylate) (PHEMA) contact lens using the Langmuir monolayer technique.

The behavior of poly(2-hydroxyethyl methacrylate) (PHEMA) polymer monolayer spread on water was studied under various experimental conditions. The influence of subphase pH and temperature, compression speed, elapsed time from the deposit of the monolayer and the recording of the surface pressure-area (π-A) isotherms, as well as the number of polymer molecules deposited at the air/water surface (surface concentration) was studied. The obtained results show that PHEMA exhibits a very stable monolayer given that it is unaffected by modifications in the majority of these variables.

Combined fluorescence and reflectance spectroscopy for in vivo quantification of cancer biomarkers in low- and high-grade glioma surgery.

Biomarkers are indicators of biological processes and hold promise for the diagnosis and treatment of disease. Gliomas represent a heterogeneous group of brain tumors with marked intra- and inter-tumor variability. The extent of surgical resection is a significant factor influencing post-surgical recurrence and prognosis.

How to obtain a well-spread monolayer of lysozyme at the air/water interfaces.

The purpose of this study is to define the conditions required to obtain a complete spreading of the lysozyme monolayer at the A/W interface. To this end, using Trurnit's method, the influence of the ionic strength of the substrate, the elapsed time between the spreading of the monolayer and the beginning of its compression, and the number of lysozyme molecules spread at the interface was studied. The results obtained show that the lysozyme spreading is conditioned by the unfolding of amino acid chains which form part of its structure, so that such unfolding is hindered, either because of an excessive accumulation of lysozyme molecules on the substrate surface or because the waiting time necessary to get this unfolding is not long enough, regardless of the number of spread molecules.

Interactions in monolayers: a study of the behavior of poly(methyl methacrylate)-lysozyme mixed films from surface pressure-area and ellipsometric measurements.

Mixed monolayers of PMMA-lysozyme show the existence of negative deviations from the additivity of the molecular areas (A(m)) when the composition of polymer mixtures is less than X(PMMA) 0.6, regardless of the surface pressure of the monolayers. The maximum deviation occurs in the mixed monolayer with composition X(PMMA) 0.

Approach to knowledge of the interaction between the constituents of contact lenses and ocular tears: mixed monolayers of poly(methyl methacrylate) and dipalmitoyl phosphatidyl choline.

Mixed monolayers of poly(methyl methacrylate) (PMMA), the main component of hard contact lenses, and dipalmitoyl phosphatidyl choline (DPPC), a characteristic phospholipidic constituent of ocular tear films, were selected as an in vitro model in order to observe the behavior of contact lenses on the eye. Using Langmuir monolayer and Brewster angle microscopy (BAM) techniques, the interaction between both components was analyzed from the data of surface pressure-area isotherms, compressional modulus-surface pressure, and relative film thickness versus time elapsed from the beginning of compression, together with BAM images. Regardless of the surface pressure at which the molecular/monomer areas (A(m)) were recorded, the A(m) mole fractions of PMMA (X(PMMA)) plots show that the experimental results match the theoretical values calculated from additivity rule A(m) = X(PMMA)A(PMMA) + X(DPPC)A(DPPC).

Automated classification of breast pathology using local measures of broadband reflectance.

We demonstrate that morphological features pertinent to a tissue's pathology may be ascertained from localized measures of broadband reflectance, with a mesoscopic resolution (100-μm lateral spot size) that permits scanning of an entire margin for residual disease. The technical aspects and optimization of a k-nearest neighbor classifier for automated diagnosis of pathologies are presented, and its efficacy is validated in 29 breast tissue specimens. When discriminating between benign and malignant pathologies, a sensitivity and specificity of 91 and 77% was achieved.

Interactions between polymers and lipid monolayers at the air/water interface: surface behavior of poly(methyl methacrylate)-cholesterol mixed films.

The behavior of mixed monolayers of cholesterol and poly(methyl methacrylate) (PMMA) with molecular weights of M(w) = 120,000 g/mol and M(w) = 15,000 g/mol was investigated at the air/water interface using Langmuir and Brewster angle microscopy techniques. From the data of surface pressure (pi)-area (A) isotherms, compressional modulus-surface pressure (C(s)(-1)-pi) curves, and film thickness, complemented with Brewster angle microscopy images, the interaction between the components was analyzed. Regardless of the surface pressure (pi = 10, 20, or 30 mN/m) at which the mean molecular/monomer areas (Am) were calculated, the Am-mole fraction plots (corresponding to X(PMMA) = 0.

Monolayer and Brewster angle microscopy studies of poly(methyl methacrylate)-monopalmitin mixed systems at the air-water interface.

Mixed monolayers of poly(methyl metacrylate) (PMMA) and monopalmitin (Mp) were used for the study of their interactions. A thorough analysis of surface pressure (pi)-area (A) isotherms with the Langmuir monolayer technique, complemented with Brewster angle microscopy (BAM) images was performed. Mixed films show two phase transitions at a surface pressure of 14.

Feasibility study of imaging spectroscopy to monitor the quality of online welding.

An online welding quality system based on the use of imaging spectroscopy is proposed and discussed. Plasma optical spectroscopy has already been successfully applied in this context by establishing a direct correlation between some spectroscopic parameters, e.g.