Teaching earth pressure theory using physical models: an example in civil engineering

The transition from basic Engineering courses in the first year of Civil Engineering curriculum, into the analysis and design of Civil Engineering structures can be challenging for students. Indeed, most students find it difficult in learning some of the theoretical courses in later years of their engineering studies. In this paper, discussions will be directed to the role of physical models in assisting the teachings of advanced Civil Engineering courses. Examples of physical models will be shown by making use of those developed by the authors in the teaching of Geotechnical Engineering at University of Southern Queensland, Australia

Evidence for Factorization in Three-body Bˉ→D(∗)K−K0\bar B\to D^{(*)} K^- K^0 Decays

Motivated by experimental results on $\bar B\to D^{(*)}K^-K^{0}$, we use a factorization approach to study these decays. Two mechanisms concerning kaon pair production arise: current-produced (from vacuum) and transition (from the $B$ meson). The kaon pair in the $\bar B {}^0\to D^{(*)+}K^-K^0$ decays can be produced only by the vector current (current-produced), whose matrix element can be extracted from $e^+e^-\to K\bar K$ processes via isospin relations. The decay rates obtained this way are in good agreement with experiment. The $B^-\to D^{(*)0}K^-K^0$ decays involve both current-produced and transition processes. By using QCD counting rules and the measured $B^-\to D^{(*)0} K^- K^0$ decay rates, the measured decay spectra can be understood.Comment: 3 pages, 6 figures. Talk presented at EPS2003 Conference, Aachen, Germany, July 200

3‘-Phosphoadenosine-5‘-phosphosulfate Reductase in Complex with Thioredoxin: A Structural Snapshot in the Catalytic Cycle

The crystal structure of Escherichia coli 3‘-phosphoadenosine-5‘-phosphosulfate (PAPS) reductase in complex with E. coli thioredoxin 1 (Trx1) has been determined to 3.0 Å resolution. The two proteins are covalently linked via a mixed disulfide that forms during nucleophilic attack of Trx's N-terminal cysteine on the Sγ atom of the PAPS reductase S-sulfocysteine (E-Cys-Sγ-SO_3^-), a central intermediate in the catalytic cycle. For the first time in a crystal structure, residues 235−244 in the PAPS reductase C-terminus are observed, depicting an array of interprotein salt bridges between Trx and the strictly conserved glutathione-like sequence, Glu^(238)Cys^(239)Gly^(240)Leu^(241)His^(242). The structure also reveals a Trx-binding surface adjacent to the active site cleft and regions of PAPS reductase associated with conformational change. Interaction at this site strategically positions Trx to bind the S-sulfated C-terminus and addresses the mechanism for requisite structural rearrangement of this domain. An apparent sulfite-binding pocket at the protein−protein interface explicitly orients the S-sulfocysteine Sγ atom for nucleophilic attack in a subsequent step. Taken together, the structure of PAPS reductase in complex with Trx highlights the large structural rearrangement required to accomplish sulfonucleotide reduction and suggests a role for Trx in catalysis beyond the paradigm of disulfide reduction

Synergistic effect of phosphodiesterase 4 inhibitor and serum on migration of endotoxin-stimulated macrophages.

Macrophage migration is an essential step in host defense against infection and wound healing. Elevation of cAMP by inhibiting phosphodiesterase 4 (PDE4), enzymes that specifically degrade cAMP, is known to suppress various inflammatory responses in activated macrophages, but the role of PDE4 in macrophage migration is poorly understood. Here we show that the migration of Raw 264.7 macrophages stimulated with LPS was markedly and dose-dependently induced by the PDE4 inhibitor rolipram as assessed by scratch wound healing assay. Additionally, this response required the involvement of serum in the culture medium as serum starvation abrogated the effect. Further analysis revealed that rolipram and serum exhibited synergistic effect on the migration, and the influence of serum was independent of PDE4 mRNA expression in LPS-stimulated macrophages. Moreover, the enhanced migration by rolipram was mediated by activating cAMP/exchange proteins directly activated by cAMP (Epac) signaling, presumably via interaction with LPS/TLR4 signaling with the participation of unknown serum components. These results suggest that PDE4 inhibitors, together with serum components, may serve as positive regulators of macrophage recruitment for more efficient pathogen clearance and wound repair

Patterns of drug use and HIV infection among adults in a nationally representative sample

Background: Little is known about drug use patterns among people living with HIV in comparison to an uninfected group in the general population. The aim of this study was to investigate the association between legal and illegal drug use and HIV infection in a nationally representative sample of adults in the United States. Methods: Public use data files (2005–2014) from the National Survey on Drug Use and Health (NSDUH) were used. Respondents were asked whether a medical professional had ever told them that they had HIV/AIDS. Ever (lifetime), past-year, and past month use of cigarettes, alcohol, marijuana, cocaine, heroin, hallucinogens, inhalants, and nonmedical use of psychotherapeutics was assessed. Logistic regression was used to estimate adjusted odds ratios (aOR) of the relationship between drug use and HIV infection, adjusting for demographics. Results: Of 377,787 respondents age 18 and older, 548 (0.19%) were categorized as HIV-infected. Ever use of cigarettes, tobacco, marijuana, cocaine, heroin, hallucinogens, inhalants, and psychotherapeutics was higher in HIV-infected individuals compared to HIV-uninfected individuals after adjustment for sex, age, race/ethnicity, education, total family income, and marital status. Past year and past month use was also higher for HIV-infected individuals for all substances aside from alcohol. Conclusions: In a nationally representative sample, there are higher levels of drug use and DSM-IV dependence among the HIV-infected population compared to the HIV-uninfected population. This is of concern because drug use and dependence can impede engagement in HIV care and adherence to antiretroviral therapy

Atoh7-independent specification of retinal ganglion cell identity

Retinal ganglion cells (RGCs) relay visual information from the eye to the brain. RGCs are the first cell type generated during retinal neurogenesis. Loss of function of the transcription facto

Impact of Maternal Periodontitis on Preterm Birth and Low Birth Weight in Babies: Results of a Scoping Review

Background Periodontitis has been documented as public health concern but its association with preterm and low birth weight remains uncertain, thus the objective of this scoping review is to summarize the most recent published evidence related to the impact of periodontitis on preterm birth and low birth weight in order to improve public awareness and to inform policies for oral health during pregnancy. Methods Hinari, PubMed, and Google Scholar were searched to acquire the published literature. The retrieved studies included cross-sectional, case control studies and randomized controlled trials with available full text published in English from 2008 to 2019. Results After combining the key words, 333 articles were identified with only 133 eligible articles published from 2008 to 2019. After reviewing the available 50 full text articles, duplicates were removed and 15 studies fully met the inclusion criteria. There were 13 articles that supported the association between maternal periodontitis and preterm low birth weight while 2 found no evidence to support the association. Conclusion The results of this scoping review contribute to an increasing body of evidence to support the hypothesis that maternal periodontal disease may be a risk factor for preterm delivery and low birth weight. Rwanda J Med Health Sci 2020;3(3):372-38