Localized moving breathers in a 2-D hexagonal lattice

We show for the first time that highly localized in-plane breathers can propagate in specific directions with minimal lateral spreading in a model 2-D hexagonal non-linear lattice. The lattice is subject to an on-site potential in addition to longitudinal nonlinear inter-particle interactions. This study investigates the prediction that stable breather-like solitons could be formed as a result of energetic scattering events in a given layered crystal and would propagate in atomic-chain directions in certain atomic planes. This prediction arose from a long-term study of previously unexplained dark lines in natural crystals of muscovite mica.Comment: 6 pages, 2 Figs. Submitted to PR

Strong and Electromagnetic Mass Splittings in Heavy Mesons

The contributions to heavy meson mass differences by the strong hyperfine interaction, the light quark masses and the electromagnetic interaction are obtained from the empirical values of the $D$, $D^*$, $B$ and $B^*$ masses by means of a mass formula based on the heavy quark mass expansion. The three different types of contributions are determined with significant accuracy to next to leading order in that expansion.Comment: 12 pages, 2 figure

Guidance and support of women in engineering programs at Universidad Tecnologica de Bolivar

Gender equality is one of the sustainable development goals. In STEM areas, it is a requirement to expand and improve women's careers. To increase the participation of women in STEM it is not enough to attract more young women to these programs. It is necessary to provide orientation during the academic programs and ensure safe and rewarding environments so that women can succeed in their studies. The Faculty of Engineering of Universidad Tecnológica de Bolívar has gender gaps in most of its programs and several strategies are being implemented to overcome this situation. This paper analyzes five factors to guide and support women in engineering programs: academic success, protection of women, scholarships and financial assistance, international mobility, and leadership. We present several activities and strategies developed in the last three years in these five factors. The impacts of these strategies cannot be evaluated yet, but we expect that they can improve the well-being of women in engineering and contribute to the reduction of the gender gaps. © 2023 IEEE

Specific pathway abundances in the neonatal calf faecal microbiome are associated with susceptibility to Cryptosporidium parvum infection: a metagenomic analysis.

Cryptosporidium parvum is the main cause of calf scour worldwide. With limited therapeutic options and research compared to other Apicomplexa, it is important to understand the parasites' biology and interactions with the host and microbiome in order to develop novel strategies against this infection. The age-dependent nature of symptomatic cryptosporidiosis suggests a link to the undeveloped immune response, the immature intestinal epithelium, and its associated microbiota. This led us to hypothesise that specific features of the early life microbiome could predict calf susceptibility to C. parvum infection. In this study, a single faecal swab sample was collected from each calf within the first week of life in a cohort of 346 animals. All 346 calves were subsequently monitored for clinical signs of cryptosporidiosis, and calves that developed diarrhoea were tested for Rotavirus, Coronavirus, E. coli F5 (K99) and C. parvum by lateral flow test (LFT). A retrospective case–control approach was taken whereby a subset of healthy calves (Control group; n = 33) and calves that went on to develop clinical signs of infectious diarrhoea and test positive for C. parvum infection via LFT (Cryptosporidium-positive group; n = 32) were selected from this cohort, five of which were excluded due to low DNA quality. A metagenomic analysis was conducted on the faecal microbiomes of the control group (n = 30) and the Cryptosporidium-positive group (n = 30) prior to infection, to determine features predictive of cryptosporidiosis. Taxonomic analysis showed no significant differences in alpha diversity, beta diversity, and taxa relative abundance between controls and Cryptosporidium-positive groups. Analysis of functional potential showed pathways related to isoprenoid precursor, haem and purine biosynthesis were significantly higher in abundance in calves that later tested positive for C. parvum (q ≤ 0.25). These pathways are either absent or streamlined in the C. parvum parasites. Though the de novo production of isoprenoid precursors, haem and purines are absent, C. parvum has been shown to encode enzymes that catalyse the downstream reactions of these pathway metabolites, indicating that C. parvum may scavenge those products from an external source. The host has previously been put forward as the source of essential metabolites, but our study suggests that C. parvum may also be able to harness specific metabolic pathways of the microbiota in order to survive and replicate. This finding is important as components of these microbial pathways could be exploited as potential therapeutic targets for the prevention or mitigation of cryptosporidiosis in bovine neonates

Flavor changing single top quark production channels at e^+e^- colliders in the effective Lagrangian description

We perform a global analysis of the sensitivity of LEP2 and e^+e^- colliders with a c.m. energy in the range 500 - 2000 GeV to new flavor-changing single top quark production in the effective Lagrangian approach. The processes considered are sensitive to new flavor-changing effective vertices such as Ztc, htc, four-Fermi tcee contact terms as well as a right-handed Wtb coupling. We show that e^+ e^- colliders are most sensitive to the physics responsible for the contact tcee vertices. For example, it is found that the recent data from the 189 GeV LEP2 run can be used to rule out any new flavor physics that can generate these four-Fermi operators up to energy scales of \Lambda > 0.7 - 1.4 TeV, depending on the type of the four-Fermi interaction. We also show that a corresponding limit of \Lambda > 1.3 - 2.5 and \Lambda > 17 - 27 TeV can be reached at the future 200 GeV LEP2 run and a 1000 GeV e^+e^- collider, respectively. We note that these limits are much stronger than the typical limits which can be placed on flavor diagonal four-Fermi couplings. Similar results hold for \mu^+\mu^- colliders and for tu(bar) associated production. Finally we briefly comment on the necessity of measuring all flavor-changing effective vertices as they can be produced by different types of heavy physics.Comment: 34 pages, plain latex, 7 figures embadded in the text using epsfig. Added new references and discussions regarding their relevance to the paper. Added more comments on the comparison between flavor-changing and flavor-diagonal contact terms and on the importance of measuring the Ztc verte

We are what we (think we) eat: The effect of expected satiety on subsequent calorie consumption

Varying expected satiety (ES) for equi-calorie portions of different foods can affect subsequent feelings of hunger and fullness and alter consumption. To our knowledge, no study has manipulated ES for an equal portion of the same solid food, appetite has not been measured >3 h and studies have not consistently measure later consumption. It is also unclear whether changes in hunger, fullness or later consumption are related to a physiological response. The aims of this study were to use the same solid food, to measure participants' response over a 4-h inter-meal period, to measure later consumption and to assess whether any effect of ES was related to a physiological (i.e. total ghrelin) response. Using a within-subjects design, 26 healthy participants had their ES for omelettes manipulated experimentally, believing that a 3-egg omelette contained either 2 (small condition) or 4 (large condition) eggs. When ES was higher (large condition) participants ate significantly fewer calories at a lunchtime test meal (mean difference = 69 kcal [± 95% CI 4–136]) and consumed significantly fewer calories throughout the day (mean difference = 167 kcal [± 95% CI 26–309]). As expected, there was a main effect of time on hunger and fullness, but no main effect of ‘portion size’ (p > .05). There was also a significant interaction between time and portion size for hunger. There was no evidence for any significant differences being the result of changes in total ghrelin. Overall, the data suggest that ES for a solid food can be manipulated and that, when given at breakfast, having a higher ES for a meal reduces lunchtime and whole day caloric consumption

Searching for chiral logs in the static-light decay constant

Using the clover fermion action in unquenched QCD with pion masses as low as 420 MeV, we look for evidence for chiral logs in the static-light decay constant. There is some evidence for a chiral log term, if the original static theory of Eichten and Hill is used. However, the more precise data from the static action of the ALPHA collaboration do not show any evidence for non-linear dependence of the static-light decay constant on the light quark mass. We make some comments on the connection between chiral perturbation theory for decay constants of the pion and static-light meson

Single-Molecule Imaging Reveals Aβ42:Aβ40 Ratio-Dependent Oligomer Growth on Neuronal Processes

AbstractSoluble oligomers of the amyloid-β peptide have been implicated as proximal neurotoxins in Alzheimer’s disease. However, the identity of the neurotoxic aggregate(s) and the mechanisms by which these species induce neuronal dysfunction remain uncertain. Physiologically relevant experimentation is hindered by the low endogenous concentrations of the peptide, the metastability of Aβ oligomers, and the wide range of observed interactions between Aβ and biological membranes. Single-molecule microscopy represents one avenue for overcoming these challenges. Using this technique, we find that Aβ binds to primary rat hippocampal neurons at physiological concentrations. Although amyloid-β(1–40) as well as amyloid-β(1–42) initially form larger oligomers on neurites than on glass slides, a 1:1 mix of the two peptides result in smaller neurite-bound oligomers than those detected on-slide or for either peptide alone. With 1 nM peptide in solution, Aβ40 oligomers do not grow over the course of 48 h, Aβ42 oligomers grow slightly, and oligomers of a 1:1 mix grow substantially. Evidently, small Aβ oligomers are capable of binding to neurons at physiological concentrations and grow at rates dependent on local Aβ42:Aβ40 ratios. These results are intriguing in light of the increased Aβ42:Aβ40 ratios shown to correlate with familial Alzheimer’s disease mutations

Coulomb Gauge QCD, Confinement, and the Constituent Representation

Quark confinement and the genesis of the constituent quark model are examined in nonperturbative QCD in Coulomb gauge. We employ a self-consistent method to construct a quasiparticle basis and to determine the quasiparticle interaction. The results agree remarkably well with lattice computations. They also illustrate the mechanism by which confinement and constituent quarks emerge, provide support for the Gribov-Zwanziger confinement scenario, clarify several perplexing issues in the constituent quark model, and permit the construction of an improved model of low energy QCD.Comment: 43 pages, 14 figures, revtex, uses psfig.st