Category: Nevin Manimala

Phys Rev E. 2023 May;107(5-1):054402. doi: 10.1103/PhysRevE.107.054402.

ABSTRACT

Purkinje cells exhibit a reduction of the mean firing rate at intermediate-noise intensities, which is somewhat reminiscent of the response enhancement known as “stochastic resonance” (SR). Although the comparison with the stochastic resonance ends here, the current phenomenon has been given the name “inverse stochastic resonance” (ISR). Recent research has demonstrated that the ISR effect, like its close relative “nonstandard SR” [or, more correctly, noise-induced activity amplification (NIAA)], has been shown to stem from the weak-noise quenching of the initial distribution, in bistable regimes where the metastable state has a larger attraction basin than the global minimum. To understand the underlying mechanism of the ISR and NIAA phenomena, we study the probability distribution function of a one-dimensional system subjected to a bistable potential that has the property of symmetry, i.e., if we change the sign of one of its parameters, we can obtain both phenomena with the same properties in the depth of the wells and the width of their basins of attraction subjected to Gaussian white noise with variable intensity. Previous work has shown that one can theoretically determine the probability distribution function using the convex sum between the behavior at small and high noise intensities. To determine the probability distribution function more precisely, we resort to the “weighted ensemble Brownian dynamics simulation” model, which provides an accurate estimate of the probability distribution function for both low and high noise intensities and, most importantly, for the transition of both behaviors. In this way, on the one hand, we show that both phenomena emerge from a metastable system where, in the case of ISR, the global minimum of the system is in a state of lower activity, while in the case of NIAA, the global minimum is in a state of increased activity, the importance of which does not depend on the width of the basins of attraction. On the other hand, we see that quantifiers such as Fisher information, statistical complexity, and especially Shannon entropy fail to distinguish them, but they show the existence of the mentioned phenomena. Thus, noise management may well be a mechanism by which Purkinje cells find an efficient way to transmit information in the cerebral cortex.

PMID:37329070 | DOI:10.1103/PhysRevE.107.054402

Phys Rev E. 2023 May;107(5):L053001. doi: 10.1103/PhysRevE.107.L053001.

ABSTRACT

The Poynting effect is a paragon of nonlinear soft matter mechanics. It is the tendency (found in all incompressible, isotropic, hyperelastic solids) exhibited by a soft block to expand vertically when sheared horizontally. It can be observed whenever the length of the cuboid is at least four times its thickness. Here we show that the Poynting effect can be easily reversed and the cuboid can shrink vertically, simply by reducing this aspect ratio. In principle, this discovery means that for a given solid, say one used as a seismic wave absorber under a building, an optimal ratio exists where vertical displacements and vibrations can be completely eliminated. Here we first recall the classical theoretical treatment of the positive Poynting effect, and then show experimentally how it can be reversed. Using finite-element simulations, we then investigate how the effect can be suppressed. We find that cubes always provide a reverse Poynting effect, irrespective of their material properties (in the third-order theory of weakly nonlinear elasticity).

PMID:37329069 | DOI:10.1103/PhysRevE.107.L053001

Phys Rev E. 2023 May;107(5-1):054128. doi: 10.1103/PhysRevE.107.054128.

ABSTRACT

Embedded random matrix ensembles with k-body interactions are well established to be appropriate for many quantum systems. For these ensembles the two point correlation function is not yet derived, though these ensembles are introduced 50 years back. Two-point correlation function in eigenvalues of a random matrix ensemble is the ensemble average of the product of the density of eigenvalues at two eigenvalues, say E and E^{‘}. Fluctuation measures such as the number variance and Dyson-Mehta Δ_{3} statistic are defined by the two-point function and so also the variance of the level motion in the ensemble. Recently, it is recognized that for the embedded ensembles with k-body interactions the one-point function (ensemble averaged density of eigenvalues) follows the so called q-normal distribution. With this, the eigenvalue density can be expanded by starting with the q-normal form and using the associated q-Hermite polynomials He_{ζ}(x|q). Covariances S_{ζ}S_{ζ^{‘}}[over ¯] (overline representing ensemble average) of the expansion coefficients S_{ζ} with ζ≥1 here determine the two-point function as they are a linear combination of the bivariate moments Σ_{PQ} of the two-point function. Besides describing all these, in this paper formulas are derived for the bivariate moments Σ_{PQ} with P+Q≤8, of the two-point correlation function, for the embedded Gaussian unitary ensembles with k-body interactions [EGUE(k)] as appropriate for systems with m fermions in N single particle states. Used for obtaining the formulas is the SU(N) Wigner-Racah algebra. These formulas with finite N corrections are used to derive formulas for the covariances S_{ζ}S_{ζ^{‘}}[over ¯] in the asymptotic limit. These show that the present work extends to all k values, the results known in the past in the two extreme limits with k/m→0 (same as q→1) and k=m (same as q=0).

PMID:37329068 | DOI:10.1103/PhysRevE.107.054128

Phys Rev E. 2023 May;107(5-2):055304. doi: 10.1103/PhysRevE.107.055304.

ABSTRACT

We present a general and numerically efficient method for calculation of collision integrals for interacting quantum gases on a discrete momentum lattice. Here we employ the original analytical approach based on Fourier transform covering a wide spectrum of solid-state problems with various particle statistics and arbitrary interaction models, including the case of momentum-dependent interaction. The comprehensive set of the transformation principles is given in detail and realized as a computer Fortran 90 library FLBE (Fast Library for Boltzmann Equation).

PMID:37329067 | DOI:10.1103/PhysRevE.107.055304

Phys Rev E. 2023 May;107(5-2):055212. doi: 10.1103/PhysRevE.107.055212.

ABSTRACT

A recent numerical treatment of data obtained by the Parker Solar Probe spacecraft describes the electron concentration in solar wind as a function of the heliocentric distance based on a Kappa distribution with spectral index κ=5. In this work, we derive and, subsequently, solve an entirely different class of nonlinear partial differential equations describing the one-dimensional diffusion of a suprathermal gas. The theory is applied to describe the aforementioned data and we find a spectral index κ≳1.5 providing the widely acknowledged identification of Kappa electrons in solar wind. We also find that suprathermal effects increase the length scale of classical diffusion by one order of magnitude. Such a result does not depend on the microscopic details of the diffusion coefficient since our theory is based on a macroscopic formulation. Forthcoming extensions of our theory by including magnetic fields and relating our formulation to nonextensive statistics are briefly addressed.

PMID:37329056 | DOI:10.1103/PhysRevE.107.055212

Phys Rev E. 2023 May;107(5-1):054139. doi: 10.1103/PhysRevE.107.054139.

ABSTRACT

A variety of transport processes in natural and man-made systems are intrinsically random. To model their stochasticity, lattice random walks have been employed for a long time, mainly by considering Cartesian lattices. However, in many applications in bounded space the geometry of the domain may have profound effects on the dynamics and ought to be accounted for. We consider here the cases of the six-neighbor (hexagonal) and three-neighbor (honeycomb) lattices, which are utilized in models ranging from adatoms diffusing in metals and excitations diffusing on single-walled carbon nanotubes to animal foraging strategy and the formation of territories in scent-marking organisms. In these and other examples, the main theoretical tool to study the dynamics of lattice random walks in hexagonal geometries has been via simulations. Analytic representations have in most cases been inaccessible, in particular in bounded hexagons, given the complicated “zigzag” boundary conditions that a walker is subject to. Here we generalize the method of images to hexagonal geometries and obtain closed-form expressions for the occupation probability, the so-called propagator, for lattice random walks both on hexagonal and honeycomb lattices with periodic, reflective, and absorbing boundary conditions. In the periodic case, we identify two possible choices of image placement and their corresponding propagators. Using them, we construct the exact propagators for the other boundary conditions, and we derive transport-related statistical quantities such as first-passage probabilities to one or multiple targets and their means, elucidating the effect of the boundary condition on transport properties.

PMID:37329046 | DOI:10.1103/PhysRevE.107.054139

Phys Rev E. 2023 May;107(5-2):055309. doi: 10.1103/PhysRevE.107.055309.

ABSTRACT

Digital cores can characterize the true internal structure of rocks at the pore scale. This method has become one of the most effective ways to quantitatively analyze the pore structure and other properties of digital cores in rock physics and petroleum science. Deep learning can precisely extract features from training images for a rapid reconstruction of digital cores. Usually, the reconstruction of three-dimensional (3D) digital cores is performed by optimization using generative adversarial networks. The training data required for the 3D reconstruction are 3D training images. In practice, two-dimensional (2D) imaging devices are widely used because they can achieve faster imaging, higher resolution, and easier identification of different rock phases, so replacing 3D images with 2D ones avoids the difficulty of acquiring 3D images. In this paper, we propose a method, named EWGAN-GP, for the reconstruction of 3D structures from a 2D image. Our proposed method includes an encoder, a generator, and three discriminators. The main purpose of the encoder is to extract statistical features of a 2D image. The generator extends the extracted features into 3D data structures. Meanwhile, the three discriminators have been designed to gauge the similarity of morphological characteristics between cross sections of the reconstructed 3D structure and the real image. The porosity loss function is used to control the distribution of each phase in general. In the entire optimization process, a strategy using Wasserstein distance with gradient penalty makes the convergence of the training process faster and the reconstruction result more stable; it also avoids the problems of gradient disappearance and mode collapse. Finally, the reconstructed 3D structure and the target 3D structure are visualized to ascertain their similar morphologies. The morphological parameter indicators of the reconstructed 3D structure were consistent with those of the target 3D structure. The microstructure parameters of the 3D structure were also compared and analyzed. The proposed method can achieve accurate and stable 3D reconstruction compared with classical stochastic methods of image reconstruction.

PMID:37329045 | DOI:10.1103/PhysRevE.107.055309

J Genet Couns. 2023 Jun 16. doi: 10.1002/jgc4.1738. Online ahead of print.

ABSTRACT

Pathogenic and likely pathogenic variants in BRCA1 and BRCA2 (BRCA1/2) are medically actionable and may inform hereditary breast and ovarian cancer (HBOC) treatment and prevention. However, rates of germline genetic testing (GT) in people with and without cancer are suboptimal. Individuals’ knowledge, attitudes, and beliefs may influence GT decisions. While genetic counseling (GC) provides decision support, the supply of genetic counselors is insufficient to meet demand. Accordingly, there is a need to explore the evidence on interventions that aim to support BRCA1/2 testing decisions. We conducted a scoping review of PubMed, CINAHL, Web of Science, and PsycINFO using search terms related to HBOC, GT, and decision making. First, we screened records to identify peer-reviewed reports that described interventions to support BRCA1/2 testing decisions. Next, we reviewed full-text reports and excluded studies that lacked statistical comparisons or enrolled previously tested individuals. Finally, we extracted study characteristics and findings into a table. All records and reports were reviewed independently by two authors; decisions were tracked in Rayyan, and discrepancies were resolved through discussion. Of 2116 unique citations, 25 met the eligibility criteria. Articles were published between 1997 and 2021 and described randomized trials and nonrandomized, quasi-experimental studies. Most studies tested technology-based (12/25, 48%) or written (9/25, 36%) interventions. Nearly half (12/25, 48%) of interventions were designed to complement traditional GC. Of the interventions compared to GC, 75% (6/8) increased or had a noninferior effect on knowledge, and 67% (4/6) decreased or had a noninferior effect on decisional conflict. Intervention effects on GT uptake were mixed, which may reflect evolving eligibility criteria for GT. Our findings suggest novel interventions may promote informed GT decision making, but many were developed to complement traditional GC. Trials that assess the effects of decision support interventions in diverse samples and evaluate implementation strategies for efficacious interventions are warranted.

PMID:37328917 | DOI:10.1002/jgc4.1738

Vet Res. 2023 Jun 16;54(1):49. doi: 10.1186/s13567-023-01180-y.

ABSTRACT

Swine dysentery (SD) caused by pathogenic Brachyspira spp. is an economic challenge for the swine industry. In research settings, experimental reproduction of swine dysentery typically relies on intragastric inoculation which has shown variable success. This project aimed to improve the consistency of the experimental inoculation protocol used for swine dysentery in our laboratory. Over six experiments, we evaluated the influence of group housing in inoculated pigs using a frozen-thawed broth culture of strongly hemolytic B. hyodysenteriae strain D19 (Trial A), compared the relative virulence of B. hyodysenteriae strains D19 and G44 (Trial B), compared inoculum volumes (50 mL vs 100 mL) for G44 and B. hampsonii 30446 (Trial C), and performed three independent trials evaluating intragastric inoculation using different oral inoculation methods: oral feed balls (Trial D), and oral syringe bolus of 100 mL (Trial E) or 300 mL (Trial F). Intragastric inoculation with a fresh broth culture of B. hyodysenteriae strain G44 resulted in a shorter incubation period and a higher proportionate duration of mucohemorrhagic diarrhea (MMHD) compared to D19. Intragastric inoculation with either 50 or 100 mL of B. hampsonii 30446 or B. hyodysenteriae (G44) were statistically equivalent. Oral inoculation with 100 mL or 300 mL also yielded similar results to intragastric inoculation but was more expensive due to the additional work and supplies associated with syringe training. Our future research will use intragastric inoculation with 100 mL of a fresh broth culture containing B. hyodysenteriae strain G44 as it yields a high incidence of mucohaemorrhagic diarrhea with a reasonable cost.

PMID:37328906 | DOI:10.1186/s13567-023-01180-y

BMC Oral Health. 2023 Jun 16;23(1):397. doi: 10.1186/s12903-023-03104-w.

ABSTRACT

BACKGROUND: Three-dimensional (3D) printing is a novel innovation in the field of craniomaxillofacial surgery, however, a lack of evidence exists related to the comparison of the trueness of skull models fabricated using different technology-based printers belonging to different cost segments.

METHODS: A study was performed to investigate the trueness of cone-beam computed tomography-derived skull models fabricated using different technology based on low-, medium-, and high-cost 3D printers. Following the segmentation of a patient’s skull, the model was printed by: (i) a low-cost fused filament fabrication printer; (ii) a medium-cost stereolithography printer; and (iii) a high-cost material jetting printer. The fabricated models were later scanned by industrial computed tomography and superimposed onto the original reference virtual model by applying surface-based registration. A part comparison color-coded analysis was conducted for assessing the difference between the reference and scanned models. A one-way analysis of variance (ANOVA) with Bonferroni correction was applied for statistical analysis.

RESULTS: The model printed with the low-cost fused filament fabrication printer showed the highest mean absolute error ([Formula: see text]), whereas both medium-cost stereolithography-based and the high-cost material jetting models had an overall similar dimensional error of [Formula: see text] and [Formula: see text], respectively. Overall, the models printed with medium- and high-cost printers showed a significantly ([Formula: see text]) lower error compared to the low-cost printer.

CONCLUSIONS: Both stereolithography and material jetting based printers, belonging to the medium- and high-cost market segment, were able to replicate the skeletal anatomy with optimal trueness, which might be suitable for patient-specific treatment planning tasks in craniomaxillofacial surgery. In contrast, the low-cost fused filament fabrication printer could serve as a cost-effective alternative for anatomical education, and/or patient communication.

PMID:37328901 | DOI:10.1186/s12903-023-03104-w