An SIS epidemic reaction-diffusion model with saturated incidence rate and spontaneous infection is considered. We establish the existence of endemic equilibrium by using a fixed point theorem. We mainly investigate the effects of diffusion and saturation on asymptotic profiles of the endemic equilibrium. Our analysis shows that the spontaneous infection can enhance persistence of infectious disease.
In this paper, motivated by Hilfer and Hilfer-Katugampola fractional derivatives, we introduce new Hilfer-generalized proportional derivatives which interpolate the classical fractional derivatives of Hilfer, Riemann-Liouville, Caputo and generalized proportional fractional derivatives. We also present some important properties of the proposed derivatives. Furthermore, as an application, we show that this equation is equivalent to the Volterra integral equation and prove the existence, uniqueness of the solution to the Cauchy problem with the nonlocal initial condition. Finally, two examples were given to illustrate the results.
In this paper, a novel beam steerable 2.4 GHz MIMO antenna array is proposed based on the Yagi-Uda principle. The antenna consists of two co-axially excited patch radiators with modified ground plane. A conducting strip with an integrated PIN diode is optimally placed between the patch radiators to act as a director or a reflector to steer the main beam by an angle of +/- 60◦. For all switching modes, the MIMO antenna demonstrates an average gain and efficiency of 5 dB and 92%, respectively, at the resonance frequency of 2.4 GHz. Reduced envelope correlation coefficient in one switching mode exhibited 17 dB improvement in mutual isolation. The simulated results agreed well with measured data. This simple, low-cost, efficient, and mutually isolated antenna array can be very useful in MIMO WLAN applications.
Hydroxyl derivatives of cinnamic acid, both natural and synthetic, are well-known antioxidants. However, not all of them feature the same radical-scavenging propensity. Establishing the relation between structure and reactivity towards radical of those species plays a crucial role in the design of novel antioxidant pharmaceuticals founded on the same parent structure. The study aims at clarifying the relationship between topology, geometry, electron and spin density distribution and the radical-scavenging activity. Different mechanisms are discussed based on the enthalpies of the possible structures generated in the process of dissociation of the OH-bonds. All structures are modelled utilizing first principles methods and accounting for the polar medium at neutral pH (B3LYP/6-311++G**/PCM). A hybrid mechanism is suggested applicable not only to hydroxylated cinnamic acids but to phenolic acids in polar environment in general.
In this study, the impacts of nitrogen loading rates on microalgal communities and intracellular storage compounds in a chemostat enrichment system were investigated. The chemostat was operated at a constant dilution rate of 0.5 d-1 with different nitrogen loading rates of 10, 20, 32.5, 42 and 63 mgN.l-1.d-1. The cultures with the lowest nitrogen loading rates showed nitrogen fixation capacity. Diverse microalgal communities were observed for nitrogen loading rates of 10 and 20 mgN.l-1.d-1. Chlorella sorokiniana and Chlorella vulgaris were dominant species at nitrogen loading rates of 42 and 32.5 mgN.l-1.d-1, respectively. Different species of Arthrospira platensis, Chlorella sp., Rhopalodia coexisted under the light-limited condition at NLR of 63 mgN.l-1.d-1. Lipids accumulation overtook starch accumulation at all nitrogen loading rates. mgN.l-1.d-1. Lipids accumulation overtook starch accumulation at all nitrogen loading rates. Specifically, the concentration of lipids in the enriched species cells, Chlorella sorokiniana was 4.2 times higher than the amount of accumulated starch. The results demonstrate that the approximately balanced addition of nutrients and light in chemostat enrichment culture could be an important trait to enrich a potential lipid production organism.
Post-glacial dispersal and colonization processes have shaped community patterns in sub-Arctic regions such as Churchill, Manitoba, Canada. Important questions remain about the species that colonized this area, in particular the role of glacial history and biological traits in governing colonization patterns from refugial and southerly geographic regions. This study quantifies sub-Arctic beetle phylogenetic community structure using the net relatedness index (NRI) and nearest taxon index (NTI); calculated using publicly available data from BOLD; compares patterns across families with different traits (habitat, diet) using standard statistical analysis (ANOVA) as well as phylogenetic generalized least squares (PGLS) using a higher-level beetle phylogeny; and compares phylogenetic community structure in Churchill with a region in southern Canada (Guelph, Ontario). The dominant pattern detected in our study was that aquatic families were much better represented in Churchill compared to terrestrial families, when compared against richness sampled from across Canada and Alaska. Individually, most families showed significant phylogenetic clustering in Churchill. Closely related species were likely found together due to the strong environmental filtering present in Arctic environments. There was no significant difference in phylogenetic structure between Churchill and Guelph, although the trend was towards stronger clustering in the North. Similarly, there was no difference in phylogenetic structure metrics calculated for aquatic vs. terrestrial beetle families, again with a trend towards stronger clustering in water beetles. By contrast, there was a significant relationship between traits and community structure. Predators showed significantly stronger clustering in Churchill compared to other feeding modes, perhaps due to phylogenetic conservatism of their overwintering ability or generalist diet of some clades within families. This study contributes to our understanding of the traits and processes structuring insect biodiversity and macroecological trends in the sub-Arctic.
Mycorrhizal fungi alter their host plant’s resistance to herbivores and their competitive ability. However, most studies on how mycorrhizae alter resistance have been conducted in single plant studies, and so the interacting effects of mycorrhizae and competition on constitutive and induced plant resistance is largely unexplored. We tested whether mycorrhizal colonization with Rhizophagus intraradice would alter herbivore performance and the expression of chemical resistance traits in tomato plants with and without intraspecific competition. We treated the plants with jasmonic acid to measure their induced chemical resistance traits which we evaluated by measuring leaf consumption by Trichoplusia ni caterpillars and two traits that affect herbivore performance: protease inhibitors, an antinutritive protein, and carbon/nitrogen ratio, a metric of plant nutritional quality. Mycorrhizae decreased resistance (increased leaf consumption) to herbivores when the plants were not in competition but had no effect in competition. While mycorrhizae reduced protease inhibitors, independent of competition or treatment with jasmonic acid, this did not increase caterpillar feeding. However, mycorrhizae, competition and induction with jasmonic acid interacted to decrease plant nutrition, measured as C/N ratio, which was correlated with caterpillar feeding. Here, we show that mycorrhizae induced decreases in plant nutritional quality; a novel mechanism by which mycorrhizae affect resistance to herbivores. Mycorrhizae and competition interact to decrease plant nutritional quality and alter resistance to herbivores.
Significant amounts of soluble product aggregates were observed in the low-pH viral inactivation (VI) opertion during an initial scale-up run for an IgG4 monoclonal antibody (mAb IgG4-N1). Being earlier in development, a scale-down model did not exist, nor was it practical to use costly Protein A eluate (PAE) for testing the VI process at scale, thus, a computational fluid dynamics (CFD)-based high molecular weight (HMW) prediction model was developed for troubleshooting and risk mitigation. It was previously reported that the IgG4-N1 molecules upon exposure to low pH tend to change into transient and partially unfolded monomers during VI acidification (i.e., VIA) and form aggregates after neutralization (i.e., VIN) (Jin et al. 2019). Therefore, the CFD model reported here focuses on the VIA step. The model mimics the continuous addition of acid to PAE and tracks acid distribution during VIA. Based on the simulated low-pH zone (≤ pH 3.3) profiles and PAE properties, the integrated low-pH zone (ILPZ) value was obtained to predict HMW level at the VI step. The simulations were performed to examine the operating parameters, such as agitation speed, acid addition rate, and protein concentration of PAE, of the pilot scale (50-200L) runs. The conditions with predictions of no product aggregation risk were recommended to the real scale-up runs, resulted in 100% success rate of the consecutive 12 pilot-scale runs. This work demonstrated that the CFD-based HMW prediction model could be used as a tool to facilitate the scale up of the low-pH VI process directly from bench to pilot/production scale.
Evaluating the factors that drive patterns of population differentiation in plants is critical for understanding several biological processes such as local adaptation and incipient speciation. Previous studies have given conflicting results regarding the significance of pollination mode, seed dispersal mode, mating system, growth form, and latitudinal region in shaping patterns of genetic structure, as estimated by FST values, and no study to date has tested their relative importance together across a broad scale. Here we assembled a 337-species dataset for seed plants from publications with data on FST from nuclear markers and species traits, including variables pertaining to the sampling scheme of each study. We used species traits, while accounting for sampling variables, to perform phylogenetic multiple regressions. Results demonstrated that FST values were higher for tropical, mixed-mating, non-woody species pollinated by small insects, indicating greater population differentiation, and lower for temperate, outcrossing trees pollinated by wind. Among the factors we tested, latitudinal region explained the largest portion of variance, followed by pollination mode, mating system and growth form, while seed dispersal mode did not significantly relate to FST. Our analyses provide the most robust and comprehensive evaluation to date of the main ecological factors predicted to drive population differentiation in seed plants, with important implications for understanding the basis of their genetic divergence. Our study is the first that we are aware of to robustly demonstrate greater population differentiation in tropical regions.
Primary biliary cholangitis (PBC) is an immune-mediated chronic cholestasis. The disruption of T cell homeostasis plays an important role in PBC pathogenesis. Lysosomal associated membrane protein 2 isoform A (LAMP-2A) has been implicated in the regulation of CD4+ T cell responses, therefore we aim to evaluate the activation state of CD4+ T cells in PBC, and to investigate the role of LAMP-2A in it. The peripheral blood of PBC patients (PBC, n=42) and healthy controls (HC, n=20) were phenotypically analyzed, and LAMP-2A expression in CD4+ T cells was assessed by flow cytometry. Naïve CD4+ T cells of PBC patients were isolated and activated in vitro to estimate their activation responses. Additionally, we assessed the changes induced by silencing LAMP-2A expression. We found that CD4+ T cells of PBC patients exhibited significant hyperactivity, and naïve CD4+ T cells showed high LAMP-2A expression, which could be a novel biomarker for PBC activity. Moreover, by interfering with LAMP-2A expression in vitro, the overreactions of PBC naïve CD4+ T cells were reversed. Our study will help to clarify that increased LAMP-2A expression in the naïve CD4+ T cells of PBC patients may lead to a tendency for increased activation responses, which may be involved in the development and progression of PBC. To reverse the hyperactivity of CD4+ T cells and reduce the resulting biliary injury, LAMP-2A could be a novel therapeutic target for the treatment of PBC.
Cyanide is a well-known constituent of mine wastewater which can be degraded by various process. However, due to cost and environmental challenges, microbial degradation seems to be the most effective process. When wastewater is treated with microorganisms, process performance should not only be based on toxicant degraded but also on the impact of the toxicant on the physical properties of the microorganisms. Heat capacity of lyophilised biomass of Fusarium oxysporum was measured using modulated differential scanning calorimeter. The heat capacity for F. oxysporum grown in cyanidation wastewater was 1.1982, 1.077 and 1.143 J K-1 g-1 on glucose (GA), Beta vulgaris (BA) and cyanide supplemented with Beta vulgaris (BCN), respectively at 298.15 K and 1 atm. The enthalpy of formation of dry biomass are -297.58, -233.07 and -278.60 kJ/C-mol for BA, BCN and GA, respectively. These values were found to be within the range of some biological molecules. The presence of cyanide in the wastewater minimally affected the thermodynamic property of the dried biomass of F. oxysporum.
Two filters using Defected Ground Structures have been proposed. First, a multiple frequency band stop filter utilizing a semi-H defect in the ground plane is presented. This structure is then prototyped on a Rogers 4350B substrate of overall size 45 mm $\times$ 15 mm, and external SMD capacitors have been employed to control the resonance of the circuit, for the stopband frequencies of 433 MHz, 700 MHz and 915 MHz. An equivalent circuit is also proposed for this multi-band design. The second filter is a combination of a band-stop and band-pass filter in one structure. The filter, operating with a controllable passband and stopband frequency is fabricated, on Rogers 4350B lossy substrate, to validate the EM and circuit simulation results. Two SMD capacitors have been loaded in the filter to control the pass band and stop band frequencies of the filter with a structure size of 20 mm x 20 mm. Furthermore, a novel equivalent circuit model encompassing the band-pass and band-stop frequency response of the DGS based filter is proposed.
Organs-on-chip are increasingly catching on as a promising and valuable alternative to animal models, in line with the 3Rs initiative, to create 3D tissue microenvironments in which cells behave physiologically and pathologically at unparalleled precision and complexity. Indeed, these platforms offer new opportunities to model human diseases and test the potential therapeutic effect of different drugs as well as their limitations, overtaking the limited predictive accuracy of conventional 2D culture systems. Here, we present a liver-on-a-chip model to investigate the effects of two naturally occurring polyphenols, namely Quercetin and Hydroxytyrosol, on non-alcoholic fatty liver disease (NAFLD) using a method of high-content analysis. NAFLD is currently the most common form of chronic liver disease, whose complex pathogenesis is far from being clear. Besides, no definitive treatment has been established for NAFLD so far. In our experiments, we observed that both polyphenols seem to restrain the progression of the free fatty acid-induced hepatocellular steatosis, showing a cytoprotective effect due to their antioxidant properties. In conclusion, the resulting insights of the present work could guide novel strategies to contrast the onset and progression of NAFLD.
The demand for electricity is increasing all over the world. In Bangladesh, there are many rural areas where the grid connection has not reached yet. In this paper, a performance evaluation was done with a solar-wind hybrid renewable energy system with diesel backup for a school located in a remote area, Baje Fulchari village in Gaibandha district, Bangladesh. For the proposed site, the load demand was considered 10.468 kWh/day for a normal working day (taken from a field survey) having peak demand of 3.3 kW. HOMER software was used for the simulation. The solar radiation and wind speed data were collected from NASA Surface meteorology and Solar Energy database. The NPC for the most economical system configuration is found USD 6,191 with a COE of 0.125 $/ kWh. Compared to the conventional power plants the proposed system can reduce the COE and GHG emission of about 29.85% and 69% respectively. The system evaluated in this work might be implemented in a school or any other location of similar load profile anywhere in the world having the same geographical and meteorological conditions.
Anthocyanins have long been suggested as having great potential in offering photoprotection to plants facing high light irradiance. Nonetheless, their effective ability in protecting the photosynthetic apparatus from supernumerary photons has been questioned in many instances, based upon the inexact belief that anthocyanins almost exclusively absorb green photons, which are instead poorly absorbed by chlorophylls. This suggestion also contrasts with the well-recognized ‘shade syndrome’ displayed by cyanic leaves: shade avoidance responses are activated indeed by excessive green light. Here we focus on the blue light absorbing features of anthocyanins, a neglected issue in anthocyanin research. We offer a comprehensive picture of the suite of molecular events activated in response to low blue-light availability, which we suggest to be responsible for the shade nature of cyanic leaves/individuals. As a corollary, this adds further support to the view of an effective photoprotective role of anthocyanins. We discuss about the morpho-anatomical adjustments imposed by the epidermal anthocyanin shield, mostly devoted at maximizing light harvesting, which make complex the analysis of the photosynthetic performance of cyanic vs acyanic leaves. Finally, we evidence major methodological issues for future research, which may help to draw conclusions on how and how much anthocyanins sustain photoprotection.
Plant adaptation to high altitudes has long been a substantial focus of ecological and evolutionary research. However, the genetic mechanisms underlying such adaptation remain poorly understood. Here, we address this issue by sampling, genotyping, and comparing populations of Tibetan poplar, Populus szechuanica var. tibetica, distributed from low (~2000 m) to high altitudes (~3000 m) of Sejila Mountain on the Qinghai-Tibet Plateau. Population structure analyses allow clear classification of two groups according to their altitudinal distributions. However, in contrast to the genetic variation within each population, differences between the two populations only explain a small portion of the total genetic variation (3.64%). We identified asymmetrical gene flow from high- to low-altitude populations. Integrating with population genomic and landscape genomic manner, we detected a hot spot region containing ten genes under natural selection and associated with five environmental factors. These genes participate in abiotic stress resistance and regulating the reproductive process. Our results provide insight into the genetic mechanisms underlying high-altitude adaptation in Tibetan poplar.
Recently diverged population in the early stages of speciation offer an opportunity to understand mechanisms of isolation and their relative contribution. Drosophila willistoni is a tropical species with broad distribution from Argentina to the southern United States, including the Caribbean islands. We have recently documented a postzygotic barrier between Central America, North America, and the northern Caribbean islands (D. w. willistoni) from South American and the southern Caribbean islands (D. w. winge). Here we identify premating isolation between strains regardless of their subspecies status, with the effect being dependent on environment. We find no evidence of postmating prezygotic isolation and proceed to characterize hybrid male sterility among the subspecies. Sterile male hybrids transfer an ejaculate that is devoid of sperm but causes elongation and expansion of the female uterus. In sterile male hybrids, bulging of the seminal vesicle appears to impede the movement of the sperm towards the sperm pump, where sperm normally mixes with accessory glands products. Our results highlight a unique form of hybrid male sterility in Drosophila that is driven by a mechanical impediment to transfer sperm rather than by an abnormality of the sperm itself. Interestingly, this form of sterility is reminiscent of a form of infertility (azoospermia) that is caused by lack of sperm in the semen due to blockages that impede the sperm from reaching the ejaculate.
Correlative evidence suggests that high problem-solving and foraging abilities in a mate are associated with direct fitness advantages, so it would benefit females to prefer problem-solving males. Recent work has also shown that females of several bird species who directly observe males prefer those that can solve a novel foraging task over those that cannot. In addition to or instead of direct observation of cognitive skills, many species utilize assessment signals when choosing a mate. Here we test whether females can select a problem-solving male over a non-solving male when presented only with a signal known to be used in mate assessment: song. Using an operant conditioning assay, we compared female zebra finch (Taeniopygia guttata) preference for the songs of males that could quickly solve a novel foraging task to the songs of males that could not solve the task. Females were never housed with the test subject males whose song they heard, and the only information provided about the males was their song. We found that females elicited more songs of problem-solving males than of non-solvers, indicating that song can contain information about a male’s ability to solve a novel foraging task and that naïve females prefer the songs of problem-solving males.