Galaxies lacking dark matter in the Illustris simulation

IB is supported by an Alexander von Humboldt research fellowship. We thank the DAAD-Ostpartnerschaftsprogramm für 2018 at the University of Bonn for funding exchange visits between Charles University in Prague and Bonn University.Context. Any viable cosmological model in which galaxies interact predicts the existence of primordial and tidal dwarf galaxies (TDGs). In particular, in the standard model of cosmology (ΛCDM), according to the dual dwarf galaxy theorem, there must exist both primordial dark matter-dominated and dark matter-free TDGs with different radii.  Aims. We study the frequency, evolution, and properties of TDGs in a ΛCDM cosmology.  Methods. We use the hydrodynamical cosmological Illustris-1 simulation to identify TDG candidates (TDGCs) and study their present-day physical properties. The positions of galaxies in the radius-mass plane, depending on their nonbaryonic content, are compared with observational data and other simulations. We also present movies on the formation of a few galaxies lacking dark matter, confirming their tidal dwarf nature. Tidal dwarf galaxy candidates can however also be formed via other mechanisms, such as from ram-pressure-stripped material or, speculatively, from cold-accreted gas.  Results. We find 97 TDGCs with Mstellar > 5 × 107M⊙ at redshift z = 0, corresponding to a co-moving number density of 2.3 × 10-4 h3 cMpc-3. The most massive TDGC has Mtotal = 3.1 × 109 M⊙, comparable to that of the Large Magellanic Cloud. Tidal dwarf galaxy candidates are phase-space-correlated, reach high metallicities, and are typically younger than dark matter-rich dwarf galaxies.  Conclusions. We report for the first time the verification of the dual dwarf theorem in a self-consistent ΛCDM cosmological simulation. Simulated TDGCs and dark matter-dominated galaxies populate different regions in the radius-mass diagram in disagreement with observations of early-type galaxies. The dark matter-poor galaxies formed in Illustris-1 have comparable radii to observed dwarf galaxies and to TDGs formed in other galaxy-encounter simulations. In Illustris-1, only 0.17 percent of all selected galaxies with Mstellar = 5 × 107-109 M⊙ are TDGCs or dark matter-poor dwarf galaxies. The occurrence of NGC 1052-DF2-type objects is discussed.Publisher PDFPeer reviewe

Salicylic acid at different plant growth stages affects secondary metabolites and phisico-chemical parameters of greenhouse tomato

Most of the researches on Salicylic acid (SA) have focused on postharvest application or acquiring stress resistance, while studies on its effect on plant growth, secondary metabolites and fruit quality are limited. SA as foliar application (0, 150, 300 and 450 mg/L) at different plant growth stages on fruit yield, secondary metabolites and quality features of tomato (Solanum lycopersicum L. cv. Kardelen) under greenhouse conditions were evaluated. The highest fruit yield per plant (about 1.3-fold greater than control) was obtained from 300 mg/L SA when applied three weeks after fruit set. Comparing to control plants, the highest fruit firmness, 10 days prolonged storability, highest total phenolics (22.6 mg gallic acid equivalent per 100 g fw); and highest antioxidant activity (65.11) were observed when 450 mg/L SA applied at fruiting stage and 3 weeks later. An increasing pattern in ascorbic acid content was observed with increasing SA concentration irrespective to application time. The same concentration effect was observed in flavonoid content when plants treated at 3 weeks after fruiting. The highest effect of flavonoids on antioxidant activity was calculated using Pearson correlation (r=0.82). SA concentrations greater than 450 mg/L showed significant adverse effects on all measured traits. The effect of exogenous SA on tomato plant depends on the developmental stage and SA concentrations tested. Improved fruit quality factors may happen in a certain concentration range, while over that may have negative or adverse effect

Effects of chicken manure and vermicompost teas on herb yield, secondary metabolites and antioxidant activity of lemon basil (Ocimum x citriodorum Vis.)

Effects of chicken manure tea (CMT) and vermicompost tea (VCT) as soil drench on vegetative growth, herb yield, essential oil content, total phenolics, total flavonoids and antioxidant activity of lemon basil (Ocimum × citriodorum Vis.) was evaluated in a two-year field experiment. The greatest plant height and number of leaves and flowers, shoot fresh and dry weight and leaf chlorophyll content were obtained using CMT at either 1:5 or 1:10 dilutions with no significant differences. The highest number of lateral branches and flavonoid content were obtained when CMT at 1:5 dilution was applied. Essential oil content was at its highest level (0.618%) when CMT or VCT were used at 1:10 dilution, while the greatest total phenolic content and total antioxidant activity were obtained at 1:5 dilution of VCT. The results emphasize the possibility of using organic-based compost teas for enhancing herbal yield and important secondary metabolites in aromatic medicinal plants

Distributed formation control of networked mechanical systems

This paper investigates a distributed formation tracking control law for large-scale networks of mechanical systems. In particular, the formation network is represented by a directed communication graph with leaders and followers, where each agent is described as a port-Hamiltonian system with a constant mass matrix. Moreover, we adopt a distributed parameter approach to prove the scalable asymptotic stability of the network formation, i.e., the scalability with respect to the network size and the specific formation preservation. A simulation case illustrates the effectiveness of the proposed control approach.Comment: 6 pages, 3 figure

Influence of arbuscular mycorrhizal fungi on physiology and fruit quality of Pepino (Solanum muricatum Ait.) in vermicompost amended medium

The association level of pepino (Solanum muricatum Ait.) with two arbuscular mycorrhizal fungi (AMF) species (Glomus etunicatum and G. versiforme) was evaluated for the first time. The first part of experiment showed 30 and 50% root colonization for the two AMF species, respectively, while the second part of study was a pot experiment under greenhouse conditions. The effects of vermicompost and root inoculation with G. etunicatum and G. versiforme on reproductive stage, yield and fruit quality of pepino were investigated. Treatments included two levels of vermicompost (0 and 20% v/v) and inoculation with the two fungi species along with a non inoculated control. Application of vermicompost increased the number of flowers, fruits and fruit weight, but decreased the number of days from plant setting to first flower and fruit set, fruit dry matter percent, fruit titratable acidity and vitamin C content. Inoculation with G. versiforme increased fruit dry matter percent, fruit titratable acidity and fruit vitamin C content compared with the non inoculated control (NIC) plants. Plants inoculated with G. etunicatum showed greater fruit weight and juice pH compared to NIC plants. AMF inoculation in vermicompost amended pots led to 14 and 10 days earlier flowering for G. versiforme and G. etunicatum, respectively compared to those not amended with vermicompost. G. etunicatum in vermicompost supplemented medium hastened fruit set by 5.5 days compared to those without vermicompost application. Fruit quality characteristics were affected differently for the two AMF-inoculated plants in presence of vermicompost

Influence of channel shape on wave-generated parameters by a pressure source in shallow water

The present work is a numerical investigation into the waves generated by a pressure source moving in straight channels with a nonrectangular cross-channel depth profile. Wave fields generated by the moving pressure source are described, and the effects of channel bathymetry on the generated wave characteristics of wave height, wave-breaking location, wave-breaking type and intensity, and peel angle are presented. Four different channel cross-section shapes were investigated, and the results were analyzed. It was concluded that the maximum wave height depended primarily on pressure-source parameters and that the investigated channel shapes did not have a significant effect on the maximum wave height. All four investigated channels were able to generate plunging-shaped breaking waves. In addition, wave-breaking intensity and barrel shape could be controlled by beach-slope shape; however, beach slope did not have a considerable effect on the wave-breaking location. The width of the deep section of the channel had a significant effect on the breaking location. Widening the deep section of the channel moved the breaking point farther from the pressure source. According to the simulation results, it is possible to generate waves for an intermediate or expert surfer only by changing the pressure-source speed. According to the results, by changing the pressure-source speed, the peel angle changes, which is the best way to change the required skill level for surfing. In addition, changing the channel shape did not have a significant effect on the required skill level for surfing

Dynamics of conflicts in Wikipedia

In this work we study the dynamical features of editorial wars in Wikipedia (WP). Based on our previously established algorithm, we build up samples of controversial and peaceful articles and analyze the temporal characteristics of the activity in these samples. On short time scales, we show that there is a clear correspondence between conflict and burstiness of activity patterns, and that memory effects play an important role in controversies. On long time scales, we identify three distinct developmental patterns for the overall behavior of the articles. We are able to distinguish cases eventually leading to consensus from those cases where a compromise is far from achievable. Finally, we analyze discussion networks and conclude that edit wars are mainly fought by few editors only.Comment: Supporting information adde

Circadian patterns of Wikipedia editorial activity: A demographic analysis

Wikipedia (WP) as a collaborative, dynamical system of humans is an appropriate subject of social studies. Each single action of the members of this society, i.e. editors, is well recorded and accessible. Using the cumulative data of 34 Wikipedias in different languages, we try to characterize and find the universalities and differences in temporal activity patterns of editors. Based on this data, we estimate the geographical distribution of editors for each WP in the globe. Furthermore we also clarify the differences among different groups of WPs, which originate in the variance of cultural and social features of the communities of editors

Removal and Dispersal of Biofluid Films by Powered Medical Devices: Modelling Infectious Agent Spreading in Dentistry

Summary Medical procedures can disperse infectious agents and spread disease. Particularly, dental procedures may pose a high risk of disease transmission as they use high-powered instruments operating within the oral cavity that may contain infectious microbiota or viruses. Here we assess the ability of powered dental devices in removing the biofluid films and identified mechanical, hydrodynamic, and aerodynamic forces as the main underlying mechanisms of removal and dispersal processes. Our results indicate that potentially infectious agents can be removed and dispersed immediately after dental instrument engagement with the adherent biofluid film while the degree of their dispersal is rapidly depleted due to removal of the source and dilution by the coolant water. We found that droplets, created by high-speed drill interactions typically travel ballistically while aerosol-laden air tends to flow as a current over surfaces. Our mechanistic investigation offers plausible routes for reducing the spread of infection during invasive medical procedures