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Quantitative Imaging in Medicine and... Feb 2022Sjögren syndrome (SjS) is a systemic disease affecting exocrine, including ocular lacrimal, glands. It is uncertain whether ocular microvascular alterations are...
BACKGROUND
Sjögren syndrome (SjS) is a systemic disease affecting exocrine, including ocular lacrimal, glands. It is uncertain whether ocular microvascular alterations are associated with this disease. In this study, we evaluated retinal and conjunctival microvascular changes in SjS patients using optical coherence tomography angiography (OCTA).
METHODS
Twelve SjS patients (24 eyes) and 12 normal controls (24 eyes) were recruited to this study. Three-dimensional conjunctival and retinal OCTA images of each eye were captured and microvascular density was calculated. Each image was analyzed by retinal area based on the early treatment of diabetic retinopathy study method (R, S, L, and I) hemisphere segmentation method (SR, SL, IL, and IR); and central wheel division method (C1-C6). Correlation analyses were used to look for associations between retinal and conjunctival microvascular densities.
RESULTS
Superficial and deep retinal layer microvascular density was decreased in SjS patients compared with normal controls (P<0.05). This significant difference was found in both superficial and deep layers in S, L, SL, IL and C1-C3 regions, and additionally in the I and SR regions in the superficial layer. Conversely, in the conjunctiva microvascular density was higher in SjS patients than in controls. In SjS patients, a significant negative correlation was found between conjunctival and both superficial (r=-0.641; P=0.025) and deep (r=-0.958; P<0.0001) microvascular densities.
CONCLUSIONS
The changed microvascular densities measured in deep and superficial retinal layers and in the conjunctiva demonstrate that OCTA is a promising method in differentiating the eyes from those with SjS.
PubMed: 35111627
DOI: 10.21037/qims-21-234 -
Chemical Engineering Science Apr 2021Motivated by analogies between the spread of infections and of chemical processes, we develop a model that accounts for infection and transport where infected...
Motivated by analogies between the spread of infections and of chemical processes, we develop a model that accounts for infection and transport where infected populations correspond to chemical species. Areal densities emerge as the key variables, thus capturing the effect of spatial density. We derive expressions for the kinetics of the infection rates, and for the important parameter , that include areal density and its spatial distribution. We present results for a batch reactor, the chemical process equivalent of the SIR model, where we examine how the dependence of on process extent, the initial density of infected individuals, and fluctuations in population densities effect the progression of the disease. We then consider spatially distributed systems. Diffusion generates traveling waves that propagate at a constant speed, proportional to the square root of the diffusivity and . Preliminary analysis shows a similar behavior for the effect of stochastic advection.
PubMed: 33518773
DOI: 10.1016/j.ces.2020.116347 -
Urbanization and translocation disrupt the relationship between host density and parasite abundance.The Journal of Animal Ecology Apr 2020The species interactions that structure natural communities are increasingly disrupted by radical habitat change resulting from the widespread processes of urbanization... (Review)
Review
The species interactions that structure natural communities are increasingly disrupted by radical habitat change resulting from the widespread processes of urbanization and species translocations. Although many species are disadvantaged by these changes, others thrive in these new environments, achieving densities that exceed those in natural habitats. Often the same species that benefit from urbanization are successful invaders in introduced habitats, suggesting that similar processes promote these species in both environments. Both processes may especially benefit certain species by modifying their interactions with harmful parasites ('enemy release'). To detect such modifications, we first need to identify the mechanisms underlying host-parasite associations in natural populations, then test whether they are disrupted in cities and introduced habitats. We studied the interaction between the cane toad Rhinella marina, a globally invasive species native to South America, and its Amblyomma ticks. Our field study of 642 cane toads across 46 sites within their native range in French Guiana revealed that 56% of toads carried ticks, and that toads with ticks were in poor body condition relative to uninfected conspecifics. Across natural and disturbed habitats tick prevalence and abundance increased with toad density, but this association was disrupted in the urban environment, where tick abundance remained low even where toad densities were high, and prevalence decreased with density. Reductions in the abundance of ticks in urban habitats may be attributable to pesticides (which are sprayed for mosquito control but are also lethal to ticks), and our literature review shows that tick abundance is generally lower in cane toads from urban habitats across South America. In the invasive range, ticks were either absent (in 1,960 toads from Puerto Rico, Hawai'i, Japan and Australia) or less abundant (in Florida and the Caribbean; literature review). The positive relationship between host density and parasite abundance is thought to be a key mechanism through which parasites regulate host populations; anthropogenic processes that disrupt this relationship may allow populations in urban and introduced habitats to persist at densities that would otherwise lead to severe impacts from parasites.
Topics: Animals; Australia; Bufo marinus; Florida; French Guiana; Introduced Species; Japan; Parasites; Puerto Rico; South America; Urbanization
PubMed: 31945186
DOI: 10.1111/1365-2656.13175 -
Scientific Reports Nov 2022A semi-analytic admixed model formalism to study the stability effects of the inner crust regions against the local collective perturbations in non-rotating neutron...
A semi-analytic admixed model formalism to study the stability effects of the inner crust regions against the local collective perturbations in non-rotating neutron stars is proposed. It consists of the viscoelastic heavy neutron-rich nuclei, superfluid neutrons, and degenerate quantum electrons. A normal spherical mode analysis yields a generalized linear dispersion relation multiparametrically mimicking the inner crust features of neutron stars. A hybrid gravito-nucleo-acoustic (GNA) instability mode is found to be excited. It is demonstrated that the electron density and the inner crust curvature act as its accelerating and antidispersive agents. In contrast, the heavy neutron-rich nucleus and neutron densities act as decelerating factors. The heavy nucleus density, electron density, and geometric curvature act as its destabilizers. It is only the neutron density that acts as the GNA stabilizing agent. The heavy neutron-rich nucleus and neutron densities are found to act as dispersive broadening factors to it. The high-[Formula: see text] regions are the more unstable spectral windows indicating that the GNA mode plays a dominant role in the inner crust zone towards the local stability. Its fair reliability is indicated in light of the recent astronomic observed scenarios. It could be useful to explore acoustic mode signatures in non-rotating neutron stars and similar other compact astroobjects.
PubMed: 36411287
DOI: 10.1038/s41598-022-23854-x -
Endocrinology Nov 2021A recent study published in The Lancet predicts a remarkable drop in population numbers following a peak that will be reached by 2064. A unique feature of the upcoming... (Review)
Review
A recent study published in The Lancet predicts a remarkable drop in population numbers following a peak that will be reached by 2064. A unique feature of the upcoming population drop is that it will be almost exclusively caused by decreased reproduction, rather than factors that increase rates of mortality. The reasons for decreased reproduction are also unique, as, unlike previous centuries, limited reproduction today is hardly due to a shortage in resources. In other words, the predicted population drop is almost exclusively due to changes in reproductive behavior and reproductive physiology. Today, global changes in reproductive behavior are mostly explained by social sciences in a framework of demographic transition hypotheses, while changes in reproductive physiology are usually attributed to effects of endocrine-disrupting pollutants. This review outlines a complementary/alternative hypothesis, which connects reproductive trends with population densities. Numerous wildlife and experimental studies of a broad range of animal species have demonstrated that reproductive behavior and reproductive physiology are negatively controlled via endocrine and neural signaling in response to increasing population densities. The causal chain of this control system, although not fully understood, includes suppression of every level of hypothalamic-pituitary-gonadal cascade by hypothalamic-pituitary-adrenal axis, activated in response to increasing stress of social interactions. This paper discusses evidence in support of a hypothesis that current trends in reproductive physiology and behavior may be partly explained by increasing population densities. Better understanding of the causal chain involved in reproduction suppression by population density-related factors may help in developing interventions to treat infertility and other reproductive conditions.
Topics: Animals; Humans; Infertility; Population Density; Population Dynamics; Reproduction; Reproductive Health; Sexual Behavior, Animal; Stress, Psychological
PubMed: 34427630
DOI: 10.1210/endocr/bqab154 -
IEEE Transactions on Pattern Analysis... Jul 2020In this paper, we present a novel non-parametric clustering technique. Our technique is based on the notion that each latent cluster is comprised of layers that surround...
In this paper, we present a novel non-parametric clustering technique. Our technique is based on the notion that each latent cluster is comprised of layers that surround its core, where the external layers, or border points, implicitly separate the clusters. Unlike previous techniques, such as DBSCAN, where the cores of the clusters are defined directly by their densities, here the latent cores are revealed by a progressive peeling of the border points. Analyzing the density of the local neighborhoods allows identifying the border points and associating them with points of inner layers. We show that the peeling process adapts to the local densities and characteristics to successfully separate adjacent clusters (of possibly different densities). We extensively tested our technique on large sets of labeled data, including high-dimensional datasets of deep features that were trained by a convolutional neural network. We show that our technique is competitive to other state-of-the-art non-parametric methods using a fixed set of parameters throughout the experiments.
PubMed: 31251176
DOI: 10.1109/TPAMI.2019.2924953 -
Computer Methods and Programs in... Mar 2021Mammographic density (MD) is conformed by a different percentage of stromal, epithelial, and adipose tissue within the breast. One of the most critical findings in...
Mammographic density (MD) is conformed by a different percentage of stromal, epithelial, and adipose tissue within the breast. One of the most critical findings in mammographic patterns for establishing a diagnosis of breast cancer is high breast tissue density. There is a wide variety of works focused on the study and automatic calculation of general breast density; however, they do not provide more detailed information about the changes that may occur within the breast tissue. This work proposes to generate a breast density map based on a texture analysis to identify the internal composition and distribution of the breast tissue through the diffuse division technique of the different densities inside the breast. Therefore, it is possible to obtain a density map associated with the breast that allows us to distinguish and quantify the different types of breast densities and their distribution according to the Breast Imaging Reporting and Data System (BI-RADS Breast Density Category). The proposed methodology was tested with mammograms from the BCDR and InBreast databases, demonstrating consistency in results and reaching an accuracy of 84.2% and 81.3%, respectively. Finally, the information obtained from the density map and its analysis could be a support tool for the specialist physician to monitor changes in breast density over time, since the fuzzy classification carried out allows quantifying the degree of membership in the BI-RADS breast density classes.
Topics: Breast; Breast Density; Breast Neoplasms; Humans; Mammography
PubMed: 33190944
DOI: 10.1016/j.cmpb.2020.105825 -
Chemical Communications (Cambridge,... Nov 2021We give an overview of the molecular response to an external magnetic field perturbing quantum mechanical systems. We present state-of-the-art methods for calculating... (Review)
Review
We give an overview of the molecular response to an external magnetic field perturbing quantum mechanical systems. We present state-of-the-art methods for calculating magnetically-induced current-density susceptibilities. We discuss the essence and properties of current-density susceptibilities and how molecular magnetic properties can be calculated from them. We also review the theory of spin-current densities, how relativity affects current densities and magnetic properties. An overview of the magnetic ring-current criterion for aromaticity is given, which has implications on theoretical and experimental research. The recently reported theory of antiaromaticity and how molecular symmetry affects the magnetic response are discussed and applied to closed-shell paramagnetic molecules. The topology of magnetically induced current densities and its consequences for molecular magnetic properties are also presented with twisted and toroidal molecules as examples.
PubMed: 34726205
DOI: 10.1039/d1cc03350f -
Annual Review of Physical Chemistry Apr 2021Kohn-Sham density functional theory with the available exchange-correlation functionals is less accurate for strongly correlated systems, which require a...
Kohn-Sham density functional theory with the available exchange-correlation functionals is less accurate for strongly correlated systems, which require a multiconfigurational description as a zero-order function, than for weakly correlated systems, and available functionals of the spin densities do not accurately predict energies for many strongly correlated systems when one uses multiconfigurational wave functions with spin symmetry. Furthermore, adding a correlation functional to a multiconfigurational reference energy can lead to double counting of electron correlation. Multiconfiguration pair-density functional theory (MC-PDFT) overcomes both obstacles, the second by calculating the quantum mechanical part of the electronic energy entirely by a functional, and the first by using a functional of the total density and the on-top pair density rather than the spin densities. This allows one to calculate the energy of strongly correlated systems efficiently with a pair-density functional and a suitable multiconfigurational reference function. This article reviews MC-PDFT and related background information.
PubMed: 33878898
DOI: 10.1146/annurev-physchem-090419-043839 -
Ecology and Evolution Oct 2023The western honey bee, , lives worldwide in approximately 102 million managed hives but also wild throughout much of its native and introduced range. Despite the... (Review)
Review
The western honey bee, , lives worldwide in approximately 102 million managed hives but also wild throughout much of its native and introduced range. Despite the global importance of as a crop pollinator, wild colonies have received comparatively little attention in the scientific literature and basic information regarding their density and abundance is scattered. Here, we review 40 studies that have quantified wild colony density directly ( = 33) or indirectly using genetic markers ( = 7) and analyse data from 41 locations worldwide to identify factors that influence wild colony density. We also compare the density of wild and managed colonies at a regional scale using data on managed colonies from the Food and Agriculture Organization (FAO). Wild colony densities varied from 0.1 to 24.2/km and were significantly lower in Europe (average of 0.26/km) than in Northern America (1.4/km), Oceania (4.4/km), Latin America (6.7/km) and Africa (6.8/km). Regional differences were not significant after controlling for both temperature and survey area, suggesting that cooler climates and larger survey areas may be responsible for the low densities reported in Europe. Managed colony densities were 2.2/km in Asia, 1.2/km in Europe, 0.2/km, in Northern America, 0.2/km in Oceania, 0.5/km in Latin America and 1/km in Africa. Wild colony densities exceeded those of managed colonies in all regions except Europe and Asia. Overall, there were estimated to be between two and three times as many wild colonies as managed worldwide. More wild colony surveys, particularly in Asia and South America, are needed to assess the relative density of wild and managed colonies at smaller spatial scales.
PubMed: 37841222
DOI: 10.1002/ece3.10609