Comment on "Interaction of two solitary waves in quantum electron-positron-ion plasma" [Phys. Plasmas \textbf{18}, 052301 (2011)]

Recently, Yan-Xia Xu, et al. in the article Ref. [Phys. Plasmas \textbf{18}, 052301 (2011)] have studied the effects of various plasma parameters on interaction of two ion-acoustic solitary waves in an unmagnetized three-dimensional electron-positron-ion quantum plasma. They have used the extended reductive perturbation technique, the so-called, extended Poincare'-Lighthill-Kuo (PLK) technique, to deduce from the model governing the quantum hydrodynamics (QHD) differential equations leading to the soliton dynamical properties, namely, Korteweg-de Vries evolution equations (one for each wave) and coupled differential equations describing the phase-shift in trajectories of solitons due to the two dimensional collision. The variation of the calculated collision phase-shifts are then numerically inspected in terms of numerous plasma fractional parameters. In this comment we give some notes specific to the validity of the results of above-mentioned article and refer to important misconceptions about the use of the Fermi-temperature in quantum plasmas, appearing in this article and many other recently published ones.Comment: Accepted Journal Physics of Plasma

Computational investigation of structure, dynamics and nucleation kinetics of a family of modified Stillinger-Weber model fluids in bulk and free-standing thin films

In recent decades, computer simulations have found increasingly widespread use as powerful tools of studying phase transitions in wide variety of systems. In the particular and very important case of aqueous systems, the commonly used force-fields tend to offer quite different predictions with respect to a wide range of thermodynamic and kinetic properties, including the ease of ice nucleation, the propensity to freeze at a vapor-liquid interface, and the existence of a liquid-liquid phase transition. It is thus of fundamental and practical interest to understand how different features of a given water model affect its thermodynamic and kinetic properties. In this work, we use the forward-flux sampling technique to study the crystallization kinetics of a family of modified Stillinger-Weber (SW) potentials with energy ($\epsilon$) and length ($\sigma$) scales taken from the monoatomic water (mW) model, but with different tetrahedrality parameters ($\lambda$). By increasing $\lambda$ from 21 to 24, we observe the nucleation rate increases by 48 orders of magnitude at a supercooling of ${\zeta}=T/T_m=0.845$. Using classical nucleation theory, we are able to demonstrate that this change can largely be accounted for by the increase in $|\Delta\mu|$, the thermodynamic driving force. We also perform rate calculations in freestanding thin films of the supercooled liquid, and observe a crossover from a surface-enhanced crystallization at $\lambda = 21$ to a bulk-dominated crystallization for $\lambda\ge22$.Comment: 10 pages, 9 figures, five table

A generalization of heterochromatic graphs

In 2006, Suzuki, and Akbari & Alipour independently presented a necessary and sufficient condition for edge-colored graphs to have a heterochromatic spanning tree, where a heterochromatic spanning tree is a spanning tree whose edges have distinct colors. In this paper, we propose $f$-chromatic graphs as a generalization of heterochromatic graphs. An edge-colored graph is $f$-chromatic if each color $c$ appears on at most $f(c)$ edges. We also present a necessary and sufficient condition for edge-colored graphs to have an $f$-chromatic spanning forest with exactly $m$ components. Moreover, using this criterion, we show that a $g$-chromatic graph $G$ of order $n$ with $|E(G)|>\binom{n-m}{2}$ has an $f$-chromatic spanning forest with exactly $m$ ($1 \le m \le n-1$) components if $g(c) \le \frac{|E(G)|}{n-m}f(c)$ for any color $c$.Comment: 14 pages, 4 figure

The morphological characters of the male external genitalia of the European hedgehog (Erinaceus Europaeus)

This study was conducted to depict anatomical characteristics of the penis of he­dgehog. Seven sexually mature male European hedgehogs were used. Following anaesthesia, the animals were scarified with chloroform inhalation. Gross penile characteristics such as length and diameter were thoroughly explored and measu­red using digital callipers. Tissue samples stained with haematoxylin and eosin and Masson’s trichrome for microscopic analysis. The penis of the European hedgehog was composed of a pair of corpus cavernosum penis and the glans penis without corpus spongiosum penis. The urethra at the end of penis, protruded as urethral process, on both sides of which two black nail-like structures, could be observed. The lower part was rounded forming a blind sac (sacculus urethralis) with a me­dian split below the urethra. Microscopically, the penile bulb lacked the corpus spongiosum penis, but, corpus spongiosum glans was seen at the beginning of the free part. In the European hedgehog, entirely stratified squamous epithelium of penile urethra, absence of corpus spongiosum penis around the urethra and bilateral urethral glands are basically different compared with other mammals. This information is expected to contribute to comparative penile morphology as well as for testing phylogenic hypotheses and expanding knowledge about reproductive biology in this animal. (Folia Morphol 2018; 77, 2: 293–300

Fear of missing out (FoMO) and internet use: A comprehensive systematic review and meta-analysis.

FoMO has been considered a predisposing factor toward excessive internet use, and a great deal of literature has investigated the link between FoMO and internet use. However, there is still a lack of cohesion in the literature. The current study have been conducted and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). In the current systematic review and meta-analysis of 86 effect-sizes, representative of 55,134 participants (Mean age = 22.07, SD = 6.15, females = 58.37%), we found that the strength of the trait FoMO- internet use association significantly varies from r = 0.11 to r = 0.63. In some populations, FoMO appears to increase with age and it is reverse in other populations. Facebook use was unrelated to FoMO in some populations, and higher FoMO was linked with stopping Instagram use for some individuals. The FoMO- internet use association was independent of their severity, as the interaction was not significant, and this association was neither linear nor curvilinear. The FoMO-internet use association does not appear to be associated with depressive, anxiety, and stress symptoms or level of life satisfaction. The COVID-19 pandemic was the only significant moderator of the FoMO-internet use association, strengthening this relationship. FoMO demonstrates a considerable role in internet use; however, there is no evidence of interaction or bi-directional association between the mentioned. Overall, we still don't know what factors contribute to individuals exhibiting distinct patterns in the FoMO-internet use association

The gross anatomy of the male reproductive system of the European hedgehog (Erinaceus Europaeus)

Hedgehogs are small spiny-coated insectivores. Due to their low body weight, calm character, and easy maintenance, they are kept as pets. It is therefore worthwhile to care about hedgehogs’ health problems and to provide pet owners with information about their reproduction. Moreover, it is necessary to be familiar with their anatomy so as to satisfy the need to improve nutrition and medical care, even surgery. This study was carried out on five adult male European hedgehogs euthanased in a chloroform chamber. The European hedgehog’s oval testes are invisible in inguinal region because they have no true scrotal sac. The testes are located in the craniocaudal direction with dorsolateral epididymal attachments. The vesicular glands, the European hedgehog’s largest accessory sex glands, are lobulated structures containing dorsomedial and ventrolateral parts on each side. The prostate is an oval gland with right and left lobes. The paired bulbourethral glands are laid on the ischiocavernosus muscle. Histologically the vesicular, prostate gland ducts and ductus deferens as well as urethra separately were discharged in a diverticlum at the level of the pelvic urethra end. A sigmoid flexure exists in the proximal part of shaft body of the penis. There are two retractor penile muscles. In dorsal end of the penile glans, there is a small urethral process with two nail- -like, needle-shaped structures. They are on both sides of the urethral process. Furthermore, there are two intromittent sacs (Sacculus urethralis) in the ventral part of the end of the penis. (Folia Morphol 2018; 77, 1: 36–43)

Influence of core stability exercise on lumbar vertebral instability in patients presented with chronic low back pain: A randomized clinical trial

Background: Excessive lumbar vertebrae translation and rotation in sagittal plane has been attributed as an associated factor of lumbar segmental instability (LSI) and low back pain (LBP). Reduction of these abnormalities improves back pain. The aim of this study was to investigate the effect of core stability exercise on the translation and rotation of lumbar vertebrae in sagittal plane in patients with nonspecific chronic LBP (NSCLBP). Methods: In this randomized clinical trial, 30 patients with NSCLBP due to LSI were included. The participants were randomly divided into two groups of treatment and control. The treatment group received general exercises plus core stability exercise for 8 weeks whereas; the control group received only general exercises. The magnitude of translation (mm) and rotation (deg) of lumbar vertebrae in the sagittal plane was determined by radiography in flexion and extension at baseline and after intervention. The primary outcome measures were to determine the mean changes from baseline in translation and rotation of the lumbar vertebrae in the sagittal plane after 8 weeks of intervention in each group. The secondary outcome was to compare the two groups in regard to translation and rotation of the lumbar vertebrae at the end of the study period. Data were analyzed using paired t-test and independent t-test. Results: Thirty patients aged 18-40 years old with clinical diagnosis of NSCLBP entered the study. Compared with baseline values, mean value of translation and rotation of the lumbar vertebra reduced significantly in both groups (P<0.05), except L3 translation in the control group. At the endpoint, mean translation value of L4 (P=0.04) and L5 (P=0.001) and rotation of the L5 (P=0.01) in the treatment group was significantly lower than the control group. Conclusion: These findings indicate that in patients presented with NSCLBP due to lumbar segmental instability, core stability exercises plus general exercises are more efficient than general exercises alone in the improvement of excessive lumbar vertebrae translation and rotation

Tropical Dominating Sets in Vertex-Coloured Graphs

Given a vertex-coloured graph, a dominating set is said to be tropical if every colour of the graph appears at least once in the set. Here, we study minimum tropical dominating sets from structural and algorithmic points of view. First, we prove that the tropical dominating set problem is NP-complete even when restricted to a simple path. Then, we establish upper bounds related to various parameters of the graph such as minimum degree and number of edges. We also give upper bounds for random graphs. Last, we give approximability and inapproximability results for general and restricted classes of graphs, and establish a FPT algorithm for interval graphs.Comment: 19 pages, 4 figure