The impact of local stellar radiation on the HI column density distribution

It is often assumed that local sources of ionizing radiation have little impact on the distribution of HI in the post-reionization Universe. While this is a good assumption for the IGM, analytic arguments suggest that local sources may typically be more important than the background radiation for high column density absorbers (N_HI > 10^17 /cm^2). We post-process cosmological simulations with accurate radiation transport to investigate the impact of local stellar sources on the HI distribution. We demonstrate that the limited numerical resolution and the simplified treatment of the ISM that are typical of current cosmological simulations provide significant challenges, but that many of the problems can be overcome by taking two steps. First, using ISM particles rather than stellar particles as sources results in a much better sampling of the source distribution. Second, by rescaling the source luminosities so that the amount of radiation escaping into the IGM agrees with that required to produce the observed background, many of the results become insensitive to errors in the predicted fraction of the radiation that escapes the immediate vicinity of the sources. By adopting this strategy and by varying the assumptions about the structure of the unresolved ISM, we conclude that we can robustly estimate the effect of local sources for column densities N_HI << 10^21 /cm^2. However, neither the escape fraction of ionizing radiation nor the effect of local sources on the abundance of N_HI >~ 10^21 systems can be predicted with confidence. We find that local stellar radiation is unimportant for N_HI << 10^17, but that it can affect Lyman Limit and DLA systems. For 10^18 < N_HI < 10^21 the impact of local sources increases with redshift. At z = 5 the abundance of absorbers with N_HI >> 10^17 is substantially reduced, but at z = 0 the reduction only becomes significant for N_HI >~ 10^21 /cm^2.Comment: 19 pages, 12 figures; Accepted for publication in MNRA

The Aurora radiation-hydrodynamical simulations of reionization: calibration and first results

We introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the small-scale structure in the gas at the resolution of the hydrodynamics, in cosmological volumes. In addition to ionizing radiation, Aurora includes galactic winds driven by star formation and the enrichment of the universe with metals synthesized in the stars. Our reference simulation uses 2x512^3 dark matter and gas particles in a box of size 25 comoving Mpc/h with a force softening scale of at most 0.28 kpc/h. It is accompanied by simulations in larger and smaller boxes and at higher and lower resolution, employing up to 2x1024^3 particles, to investigate numerical convergence. All simulations are calibrated to yield simulated star formation rate (SFR) functions in close agreement with observational constraints at redshift z = 7 and to achieve reionization at z = 8.3, which is consistent with the observed optical depth to reionization. We focus on the design and calibration of the simulations and present some first results. The median stellar metallicities of low-mass galaxies at z = 6 are consistent with the metallicities of dwarf galaxies in the Local Group, which are believed to have formed most of their stars at high redshifts. After reionization, the mean photoionization rate decreases systematically with increasing resolution. This coincides with a systematic increase in the abundance of neutral hydrogen absorbers in the IGM.Comment: 16 pages, 8 figures, accepted for publication in MNRA

Therapeutic potential of quercetin on human breast cancer in different dimensions

Background: There has been an extensive range of incidence and mortality of breast cancer (BC), and the comprehensively available treatments for BC have not been completely successful in achieving satisfactory outcomes up to date. Hypothesis: Recently, we are watching intense attention paid to the utilization of natural compounds as a novel therapeutic strategy for cancer treatment. Quercetin, a dietary flavonol in a large group of commonly consumed foods, is widely illustrated to apply inhibitory effects on cancer progression through several mechanisms including apoptosis enhancement, cell cycle arrest, metastasis and angiogenesis inhibition, antioxidant replication and estrogen receptor modulation. Methods: We reviewed the most relevant papers published from 2009 to 2018 (except 15 articles), using �pub med� and �web of science� and the search terms �Quercetin�; �Breast cancer�; �Flavonoid�; �Apoptosis�; �Cell cycle�; �chemotherapy�; �Drug resistance�; �Metastasis; �Oxidative stress�, �Breast cancer receptors� and �Quercetin derivatives�. We selected studies on the association of quercetin with breast cancer in different dimensions. Results: Despite the remarkable number of studies on quercetin�s efficacy, multiple aspects of this herbal compound have not been clarified well and this review provides a summarized update of the recent evidence on biologically available efficacies of quercetin which would establish a further biological basis for the potential therapeutic acquisition of quercetin as an anticancer drug. Conclusion: Basic, epidemiological and genetic studies point to the potential role of quercetin in the treatment of breast cancer, but randomized and controlled trials are of great importance to establish the clinical efficacy of quercetin in ill or at-risk subjects. © 2019, Springer Nature Switzerland AG

Dynamic Behavior of Droplet Impact on Inclined Surfaces with Acoustic Waves

Droplet impact on arbitrary inclined surfaces is of great interest for applications such as antifreezing, self-cleaning, and anti-infection. Research has been focused on texturing the surfaces to alter the contact time and rebouncing angle upon droplet impact. In this paper, using propagating surface acoustic waves (SAWs) along the inclined surfaces, we present a novel technique to modify and control key droplet impact parameters, such as impact regime, contact time, and rebouncing direction. A high-fidelity finite volume method was developed to explore the mechanisms of droplet impact on the inclined surfaces assisted by SAWs. Numerical results revealed that applying SAWs modifies the energy budget inside the liquid medium, leading to different impact behaviors. We then systematically investigated the effects of inclination angle, droplet impact velocity, SAW propagation direction, and applied SAW power on the impact dynamics and showed that by using SAWs, droplet impact on the nontextured hydrophobic and inclined surface is effectively changed from deposition to complete rebound. Moreover, the maximum contact time reduction up to ∼50% can be achieved, along with an alteration of droplet spreading and movement along the inclined surfaces. Finally, we showed that the rebouncing angle along the inclined surface could be adjusted within a wide range

The localization of amyloid precursor protein to ependymal cilia in vertebrates and its role in ciliogenesis and brain development in zebrafish

Amyloid precursor protein (APP) is expressed in many tissues in human, mice and in zebrafish. In zebrafish, there are two orthologues, Appa and Appb. Interestingly, some cellular processes associated with APP overlap with cilia-mediated functions. Whereas the localization of APP to primary cilia of in vitro-cultured cells has been reported, we addressed the presence of APP in motile and in non-motile sensory cilia and its potential implication for ciliogenesis using zebrafish, mouse, and human samples. We report that Appa and Appb are expressed by ciliated cells and become localized at the membrane of cilia in the olfactory epithelium, otic vesicle and in the brain ventricles of zebrafish embryos. App in ependymal cilia persisted in adult zebrafish and was also detected in mouse and human brain. Finally, we found morphologically abnormal ependymal cilia and smaller brain ventricles in appa-/-appb-/- mutant zebrafish. Our findings demonstrate an evolutionary conserved localisation of APP to cilia and suggest a role of App in ciliogenesis and cilia-related functions

Assessment of Bond Strength between Metal Brackets and Non-Glazed Ceramic in Different Surface Treatment Methods

Objective: The aim of this study was to evaluate the bond strength between metal brackets and non-glazed ceramic with three different surface treatment methods.Materials and Methods: Forty-two non-glazed ceramic disks were assigned into three groups. Group I and II specimens were etched with 9.5% hydrofluoric acid. Subsequently in group I, silane and adhesive were applied and in group II, bonding agent was used only.In group III, specimens were treated with 35% phosphoric acid and then silane and adhesive were applied. Brackets were bonded with light-cured composites. The specimens were stored in water in room temperature for 24 hours and then thermocycled 500 times between 5°C and 55°C.Results: The difference of tensile bond strength between groups I and III was not significant(P=0.999). However, the tensile bond strength of group II was significantly lower than groups I, and III (P<0.001). The adhesive remnant index scores between the threegroups had statistically significant differences (P<0.001).Conclusion: With the application of scotch bond multi-purpose plus adhesive, we can use phosphoric acid instead of hydrofluoric acid for bonding brackets to non-glazed ceramic restorations

Determinants of lifestyle behavior in Iranian adults with prediabetes: Applying the theory of planned behavior

© 2017, Academy of Medical Sciences of I.R. Iran. All rights reserved. OBJECTIVE: Prediabetic condition can lead to development of type 2 diabetes, especially in individuals who do not adhere to a healthy lifestyle. The aim of the present study was to investigate the socio-cognitive factors using the Theory of Planned Behavior (TPB) that may be associated with the choice of lifestyle in prediabetic patients. METHODS: A prospective study with one-month follow up was designed to collect data from 350 individuals with prediabetic conditions. A questionnaire was used to collect the information, including demographic variables, exercise behavior, food consumption, as well as the constructs of the TPB (attitude, subjective norms, perceived behavioral control, and behavioral intention) regarding physical activity and dietary choice. The correlations between TPB variables and the dependent variables (dietary choice, physical activity) were assessed using Spearman correlation and multiple regression models. RESULT: In total, 303 people participated. The mean age of the participants was 53.0 (SD 11.5) years and 42% were males. Significant correlations were found between all TPB constructs and both dependent variables (healthy eating and exercise behaviors) both at baseline and after one month (P < 0.01). The predictive validity of the TPB over time was proved for both dependent variables where past and future behaviors were significantly correlated with the constructs. Nearly 87% of the variance in exercise behavior and 72% of the variance in healthy eating behavior were explainable by TPB constructs. CONCLUSION: The TPB may be a useful model to predict behaviors of physical activity and dietary choice among prediabetic people. Therefore, it may be used to monitor lifestyle modification to prevent development of diabetes among people with prediabetic conditions