Defining perturbations on submanifolds

We study the definition of perturbations in the presence of a submanifold, like e.g. a brane. In the standard theory of cosmological perturbations, one compares quantities at the same coordinate points in the non-perturbed and the perturbed manifolds, identified via a (non-unique) mapping between the two manifolds. In the presence of a physical submanifold one needs to modify this definition in order to evaluate perturbations of quantities at the submanifold location. As an application, we compute the perturbed metric and the extrinsic curvature tensors at the brane position in a general gauge

Superficial Surface Treatment using Atmospheric Plasma on Recycled Nylon 6,6

Polymers currently represent materials that are cost-effective, while its recycled nature is significant in terms of environmental protection. However, the surface properties of polymers often do not meet the demands of wettability, adhesion, and friction, among others. Atmospheric plasma treatment on the surface of polymers improves its physical-chemistry properties. In this work, a recycled nylon coating was prepared by the spin coating technique and characterized by Fourier transform infrared spectroscopy and X-ray diffraction. This coating was treated by atmospheric plasma, and Raman spectroscopy was performed to analyze the signals related to different functional groups present in the coating surface after plasma treatment. The action of plasma on the surface morphology was observed by scanning electron microscopy. The contact angle results showed an improvement in surface wettability

Computational and analytical studies of the harmonic index on Erdös-Rényi models

A main topic in the study of topological indices is to find bounds of the indices involving several parameters and/or other indices. In this paper we perform statistical (numerical) and analytical studies of the harmonic index H(G), and other topological indices of interest, on Erdos-Rényi (ER) graphs G(n, p) characterized by n vertices connected independently with probability p ∈ (0, 1). Particularly, in addition to H(G), we study here the (−2) sum-connectivity index χ−2(G), the modified Zagreb index MZ(G), the inverse degree index ID(G) and the Randic index R(G). First, to perform the statistical study of these indices, we define the averages of the normalized indices to their maximum value: {H(G)}, {χ−2(G)}, {MZ(G)}, {ID(G)}, {R(G)}. Then, from a detailed scaling analysis, we show that the averages of the normalized indices scale with the product ξ ≈ np. Moreover, we find two different behaviors. On the one hand, hH(G)i and hR(G)i, as a function of the probability p, show a smooth transition from zero to n/2 as p increases from zero to one. Indeed, after scaling, it is possible to define three regimes: a regime of mostly isolated vertices when ξ 10 (H(G), R(G) ≈ n/2). On the other hand, hχ−2(G)i, hMZ(G)i and hID(G)i increase with p until approaching their maximum value, then they decrease by further increasing p. Thus, after scaling the curves corresponding to these indices display bell-like shapes in log scale, which are symmetric around ξ ≈ 1; i.e. the percolation transition point of ER graphs. Therefore, motivated by the scaling analysis, we analytically (i) obtain new relations connecting the topological indices H, χ−2, MZ, ID and R that characterize graphs which are extremal with respect to the obtained relations and (ii) apply these results in order to obtain inequalities on H, χ−2, MZ, ID and R for graphs in ER models.J.A.M.-B. acknowledges financial support from FAPESP (Grant No. 2019/ 06931-2), Brazil, CONACyT (Grant No. 2019-000009-01EXTV-00067) and PRODEP-SEP (Grant No. 511-6/2019.-11821), Mexico. J.M.R. and J.M.S. acknowledge financial support from Agencia Estatal de Investigación (PID2019-106433GB-I00/AEI/ 10.13039/501100011033), Spain

Spectral Measures of Bipartivity in Complex Networks

We introduce a quantitative measure of network bipartivity as a proportion of even to total number of closed walks in the network. Spectral graph theory is used to quantify how close to bipartite a network is and the extent to which individual nodes and edges contribute to the global network bipartivity. It is shown that the bipartivity characterizes the network structure and can be related to the efficiency of semantic or communication networks, trophic interactions in food webs, construction principles in metabolic networks, or communities in social networks.Comment: 16 pages, 1 figure, 1 tabl

Bicarbonate-Triggered In Vitro Capacitation of Boar Spermatozoa Conveys an Increased Relative Abundance of the Canonical Transient Receptor Potential Cation (TRPC) Channels 3, 4, 6 and 7 and of CatSper-γ Subunit mRNA Transcripts

Sperm capacitation is a stepwise complex biochemical process towards fertilization. It includes a crucial early calcium (Ca2+) transport mediated by CatSper channels and Canonical Transient Potential Channels (TRPC). We studied the relative abundance of mRNA transcripts changes of the CatSper β, γ and δ subunits and TRPC-channels 1, 3, 4, 6 and 7 in pig spermatozoa, after triggering in vitro capacitation by bicarbonate ions at levels present in vivo at the fertilization site. For this purpose, we analyzedfive5 ejaculate pools (from three fertile adult boars) before (control-fresh samples) and after in vitro exposure to capacitation conditions (37 mM NaHCO3, 2.25 mM CaCl2, 2 mM caffeine, 0.5% bovine serum albumin and 310 mM lactose) at 38 °C, 5% CO2 for 30 min. In vitro capacitation using bicarbonate elicits an increase in the relative abundance of mRNA transcripts of almost all studied Ca2+ channels, except CatSper-δ and TRPC1 (significantly reduced). These findings open new avenues of research to identify the specific role of each channel in boar sperm capacitation and elucidate the physiological meaning of the changes on sperm mRNA cargo

Semen Modulates the Expression of NGF, ABHD2, VCAN, and CTEN in the Reproductive Tract of Female Rabbits

Semen changes the gene expression in endometrial and oviductal tissues modulating important processes for reproduction. We tested the hypothesis that mating and/or sperm-free seminal plasma deposition in the reproductive tract affect the expression of genes associated with sperm-lining epithelium interactions, ovulation, and pre-implantation effects (nerve growth factor, NGF; α/β hydrolase domain-containing protein 2, ABHD2; C-terminal tensin-like protein, CTEN or TNS4; and versican, VCAN) in the period 10-72 h post-mating. In Experiment 1, does (n = 9) were treated with gonadotropin-releasing hormone (GnRH) (control), GnRH-stimulated, and vaginally infused with sperm-free seminal plasma (SP-AI), or GnRH-stimulated and naturally mated (NM). In Experiment 2, does (n = 15) were GnRH-stimulated and naturally mated. Samples were retrieved from the internal reproductive tracts (cervix-to-infundibulum) 20 h post-treatment (Experiment 1) or sequentially collected at 10, 24, 36, 68, or 72 h post-mating (Experiment 2, 3 does/period). All samples were processed for gene expression analysis by quantitative PCR. Data showed an upregulation of endometrial CTEN and NGF by NM, but not by SP-AI. The findings suggest that the NGF gene affects the reproductive tract of the doe during ovulation and beyond, influencing the maternal environment during early embryonic development

Semen Modulates the Expression of NGF, ABHD2, VCAN, and CTEN in the Reproductive Tract of Female Rabbits

Semen changes the gene expression in endometrial and oviductal tissues modulating important processes for reproduction. We tested the hypothesis that mating and/or sperm-free seminal plasma deposition in the reproductive tract affect the expression of genes associated with sperm-lining epithelium interactions, ovulation, and pre-implantation effects (nerve growth factor, NGF; α/β hydrolase domain-containing protein 2, ABHD2; C-terminal tensin-like protein, CTEN or TNS4; and versican, VCAN) in the period 10-72 h post-mating. In Experiment 1, does (n = 9) were treated with gonadotropin-releasing hormone (GnRH) (control), GnRH-stimulated, and vaginally infused with sperm-free seminal plasma (SP-AI), or GnRH-stimulated and naturally mated (NM). In Experiment 2, does (n = 15) were GnRH-stimulated and naturally mated. Samples were retrieved from the internal reproductive tracts (cervix-to-infundibulum) 20 h post-treatment (Experiment 1) or sequentially collected at 10, 24, 36, 68, or 72 h post-mating (Experiment 2, 3 does/period). All samples were processed for gene expression analysis by quantitative PCR. Data showed an upregulation of endometrial CTEN and NGF by NM, but not by SP-AI. The findings suggest that the NGF gene affects the reproductive tract of the doe during ovulation and beyond, influencing the maternal environment during early embryonic development

Semen Modulates the Expression of NGF, ABHD2, VCAN, and CTEN in the Reproductive Tract of Female Rabbits

Semen changes the gene expression in endometrial and oviductal tissues modulating important processes for reproduction. We tested the hypothesis that mating and/or sperm-free seminal plasma deposition in the reproductive tract affect the expression of genes associated with sperm-lining epithelium interactions, ovulation, and pre-implantation effects (nerve growth factor, NGF; α/β hydrolase domain-containing protein 2, ABHD2; C-terminal tensin-like protein, CTEN or TNS4; and versican, VCAN) in the period 10-72 h post-mating. In Experiment 1, does (n = 9) were treated with gonadotropin-releasing hormone (GnRH) (control), GnRH-stimulated, and vaginally infused with sperm-free seminal plasma (SP-AI), or GnRH-stimulated and naturally mated (NM). In Experiment 2, does (n = 15) were GnRH-stimulated and naturally mated. Samples were retrieved from the internal reproductive tracts (cervix-to-infundibulum) 20 h post-treatment (Experiment 1) or sequentially collected at 10, 24, 36, 68, or 72 h post-mating (Experiment 2, 3 does/period). All samples were processed for gene expression analysis by quantitative PCR. Data showed an upregulation of endometrial CTEN and NGF by NM, but not by SP-AI. The findings suggest that the NGF gene affects the reproductive tract of the doe during ovulation and beyond, influencing the maternal environment during early embryonic development

Hole spin driving by strain-induced spin-orbit interactions

Hole spins in semiconductor quantum dots can be efficiently manipulated with radio-frequency electric fields owing to the strong spin-orbit interactions in the valence bands. Here we show that the motion of the dot in inhomogeneous strain fields gives rise to linear Rashba spin-orbit interactions (with spatially dependent spin-orbit lengths) and g-factor modulations that allow for fast Rabi oscillations. Such inhomogeneous strains may build up spontaneously due to process and cool down stress. We discuss spin qubits in Ge/GeSi heterostructures as an illustration. We highlight that Rabi frequencies can be enhanced by one order of magnitude by shear strain gradients as small as $3\times 10^{-6}$ nm$^{-1}$ within the dots. This underlines that spin in solids can be very sensitive to strains and opens the way for strain engineering in hole spin devices for quantum information and spintronics.Comment: 19 pages, 3 figure