Dielectric properties measurements of brown and white adipose tissue in rats from 0.5 to 10 GHz

Brown adipose tissue (BAT) plays an important role in whole body metabolism and with appropriate stimulus could potentially mediate weight gain and insulin sensitivity. Although imaging techniques are available to detect subsurface BAT, there are currently no viable methods for continuous acquisition of BAT energy expenditure. Microwave (MW) radiometry is an emerging technology that allows the quantification of tissue temperature variations at depths of several centimeters. Such temperature differentials may be correlated with variations in metabolic rate, thus providing a quantitative approach to monitor BAT metabolism. In order to optimize MW radiometry, numerical and experimental phantoms with accurate dielectric properties are required to develop and calibrate radiometric sensors. Thus, we present for the first time, the characterization of relative permittivity and electrical conductivity of brown (BAT) and white (WAT) adipose tissues in rats across the MW range 0.5-10GHz. Measurements were carried out in situ and post mortem in six female rats of approximately 200g. A Cole-Cole model was used to fit the experimental data into a parametric model that describes the variation of dielectric properties as a function of frequency. Measurements confirm that the dielectric properties of BAT (εr = 14.0-19.4, σ = 0.3-3.3S/m) are significantly higher than those of WAT (εr = 9.1-11.9, σ = 0.1-1.9S/m), in accordance with the higher water content of BAT

Study of the one dimensional and transient bioheat transfer equation: Multi-layer solution development and applications

: In this work we derive an analytical solution given by Bessel series to the transient and one-dimensional (1D) bioheat transfer equation in a multi-layer region with spatially dependent heat sources. Each region represents an independent biological tissue characterized by temperature-invariant physiological parameters and a linearly temperature dependent metabolic heat generation. Moreover, 1D Cartesian, cylindrical or spherical coordinates are used to define the geometry and temperature boundary conditions of first, second and third kinds are assumed at the inner and outer surfaces. We present two examples of clinical applications for the developed solution. In the first one, we investigate two different heat source terms to simulate the heating in a tumor and its surrounding tissue, induced during a magnetic fluid hyperthermia technique used for cancer treatment. To obtain an accurate analytical solution, we determine the error associated with the truncated Bessel series that defines the transient solution. In the second application, we explore the potential of this model to study the effect of different environmental conditions in a multi-layered human head model (brain, bone and scalp). The convective heat transfer effect of a large blood vessel located inside the brain is also investigated. The results are further compared with a numerical solution obtained by the Finite Element Method and computed with COMSOL Multi-physics v4.1 (c). (c) 2013 Elsevier Ltd. All rights reserved

Interplay between static and dynamic polar correlations in relaxor Pb(Mg_{1/3}Nb_{2/3})O_{3}

We have characterized the dynamics of the polar nanoregions in Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ (PMN) through high-resolution neutron backscattering and spin-echo measurements of the diffuse scattering cross section. We find that the diffuse scattering intensity consists of \emph{both} static and dynamic components. The static component first appears at the Curie temperature $\Theta \sim 400$ K, while the dynamic component freezes completely at the temperature T$_{f} \sim 200$ K; together, these components account for all of the observed spectral weight contributing to the diffuse scattering cross section. The integrated intensity of the dynamic component peaks near the temperature at which the frequency-dependent dielectric constant reaches a maximum (T$_{max}$) when measured at 1 GHz, i. e. on a timescale of $\sim 1$ ns. Our neutron scattering results can thus be directly related to dielectric and infra-red measurements of the polar nanoregions. Finally, the global temperature dependence of the diffuse scattering can be understood in terms of just two temperature scales, which is consistent with random field models.Comment: (8 pages, 5 figures, submitted to Phys. Rev. B

Speckle observations of the binary asteroid (22) Kalliope with C2PU/PISCO

We present new speckle measurements of the position of Linus, the satellite of the asteroid (22) Kalliope, obtained at the 1m C2PU-Epsilon telescope on the Plateau de Calern, France. Observations were made in the visible domain with the speckle camera PISCO. We obtained 122 measurements in February-March 2022 and April 2023, with a mean uncertainty close to 10 milli-arcseconds on the angular separation

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset

Shedding light on membrane-templated clustering of gold nanoparticles

The use of inorganic nanoparticles in biomedical and biotechnological applications requires a molecular-level understanding of interactions at nano-bio interfaces, such as cell membranes. Several recent reports have shown that gold nanoparticles (AuNP), in the presence of fluid lipid bilayers, aggregate at the lipid/aqueous interface, but the precise origin of this phenomenon is still not fully understood. Here, by challenging synthetic lipid membranes with one of the most typical classes of nanomaterials, citrate-coated AuNP, we addressed the cooperative nature of their interaction at the interface, which leads to AuNP clustering. The ensemble of optical (UV–Vis absorbance), structural (small-angle neutron and X-ray scattering) and surface (X-ray reflectivity, quartz crystal microbalance, atomic force microscopy) results, is consistent with a mechanistic hypothesis, where the citrate-lipid ligand exchange at the interface is the molecular origin of a multiscale cooperative behavior, which ultimately leads to the formation of clusters of AuNP on the bilayer. This mechanism, fully consistent with the data reported so far in the literature for synthetic bilayers, would shed new light on the interaction of engineered nanomaterials with biological membranes. The cooperative nature of ligand exchange at the AuNP-liposome interface, pivotal in determining clustering of AuNP, will have relevant implications for NP use in Nanomedicine, since NP will be internalized in cells as clusters, rather than as primary NP, with dramatic effects on their bioactivity

Semen parameters and male reproductive potential are not adversely affected after three or more months of recovery from COVID-19 disease

Background: The male reproductive system may be a potential target for SARS-CoV-2 since the presence of ACE and TMPRS2 receptors. After a first report of the presence of SARS-CoV-2 in semen of COVID-19 patients, several papers reported that SARS-CoV-2 was not detected in the semen. However, some evidences indicated that COVID-19 disease could impair semen parameters. During the infection, or in a short period after, a reduction in sperm concentration and motility and an increase in DNA fragmentation were observed, even in asymptomatic patients. There is no conclusive data exploring whether this damage changes with time. We investigated whether COVID-19 disease has a negative impact on semen parameters and male reproductive potential after recovery. Methods: In this longitudinal retrospective study, we enrolled 20 men who had COVID-19 disease. We compared sperm parameters in samples collected before COVID-19 and after infection (8.3 ± 4.8 months). We also evaluated the reproductive potential in pre- and post-COVID-19 infertility treatments of 8 self-controlled couples as well as in 40 cycles after COVID-19 infection of the male partner. Results: For most patients, we obtained results of more than one semen analysis before and after COVID-19. After adjusting for age, days of sexual abstinence, frequency of ejaculations and presence of fever, we found no significant difference over time in any semen parameter. The interval between COVID-19 infection and subsequent infertility treatments was 10.7 ± 7.5 months. There were no differences in the embryological and clinical outcomes of infertility treatments performed before and after male infection. One couple obtained a single pregnancy in the post COVID-19 IUI. Normal fertilization (65%), cleavage (99%) and blastocyst development (40%) rates in treatments performed after male infection were within the expected range of competencies. A total of 5 singleton and 1 twin clinical pregnancies were obtained, and 6 healthy children were born. A total of 10 blastocysts have been cryopreserved. Conclusion: Our data are reassuring that COVID-19 disease has no negative effect on semen quality and male reproductive potential when semen samples are collected three months or more after infection