Phase structure of the O(2)O(2) ghost model with higher-order gradient term

The phase structure and the infrared behaviour of the Euclidean 3-dimensional $O(2)$ symmetric ghost scalar field model with higher-order derivative term has been investigated in Wegner and Houghton's renormalization group framework. The symmetric phase in which no ghost condensation occurs and the phase with restored symmetry but with a transient presence of a ghost condensate have been identified. Finiteness of the correlation length at the phase boundary hints to a phase transition of first order. The results are compared with those for the ordinary $O(2)$ symmetric scalar field model.Comment: 15 pages, 13 figure

Particle in a cavity in one-dimensional bandlimited quantum mechanics

The effects of the generalized uncertainty principle (GUP) on the low-energy stationary states of a particle moving in a cavity with no sharp boundaries are determined by means of the perturbation expansion in the framework of one-dimensional bandlimited quantum mechanics. A realization of GUP resulting in the existence of a finite ultraviolet (UV) wave-vector cutoff $K\sim 1/\ell_P$ (with the Planck length $\ell_P$) is considered. The cavity of the size $\ell \gg \ell_P$ is represented by an infinitely deep trapezoid-well potential with boundaries smeared out in a range $R$ satisfying the inequalities $\ell\gg R\gtrsim \ell_P$. In order to determine the energy shifts of the low-lying stationary states, the usual perturbation expansion is reformulated in a manner that enables one to treat consistently order-by-order the direct and indirect GUP effects, i.e., those due to the modification of the Hamiltonian and the lack of the UV modes, respectively. It is shown that the leading terms of the indirect and the direct GUP effects are of the first and second order, respectively, in the small parameter $\ell_P/\ell$ in agreement with our previous finding in a more naive approach [1].Comment: 17 page

Effect of the quartic gradient terms on the critical exponents of the Wilson-Fisher fixed point in O(N) models

The effect of the \ord{\partial^4} terms of the gradient expansion on anomalous dimension $\eta$ and the correlation length's critical exponent $\nu$ of the Wilson-Fisher fixed point has been determined for the Euclidean $O(N)$ model for $N=1$ and the number of dimensions $2< d<4$ as well as for $N\ge 2$ and $d=3$. Wetterich's effective average action renormalization group method is used with field-independent derivative couplings and Litim's optimized regulator. It is shown that the critical theory for $N\ge 2$ is well approximated by the effective average action preserving $O(N)$ symmetry with the accuracy of \ord{\eta}.Comment: 19 pages, 27 figure

TORC1 Determines Fab1 Lipid Kinase Function at Signaling Endosomes and Vacuoles

Organelles of the endomembrane system maintain their identity and integrity during growth or stress conditions by homeostatic mechanisms that regulate membrane flux and biogenesis. At lysosomes and endosomes, the Fab1 lipid kinase complex and the nutrient-regulated target of rapamycin complex 1 (TORC1) control the integrity of the endolysosomal homeostasis and cellular metabolism. Both complexes are functionally connected as Fab1-dependent generation of PI(3,5)P2 supports TORC1 activity. Here, we identify Fab1 as a target of TORC1 on signaling endosomes, which are distinct from multivesicular bodies, and provide mechanistic insight into their crosstalk. Accordingly, TORC1 can phosphorylate Fab1 proximal to its PI3P-interacting FYVE domain, which causes Fab1 to shift to signaling endosomes, where it generates PI(3,5)P2. This, in turn, regulates (1) vacuole morphology, (2) recruitment of TORC1 and the TORC1-regulatory Rag GTPase-containing EGO complex to signaling endosomes, and (3) TORC1 activity. Thus, our study unravels a regulatory feedback loop between TORC1 and the Fab1 complex that controls signaling at endolysosomes

Effect of elevated CO2 on lycopene content of tomato (Lycopersicon lycopersicum L. Karsten) fruits

Recently several studies have focused on the antioxidant activity of lycopene such as quenching of singlet oxygen and scavenging of peroxyl radicals. These properties may play a role in the prevention of different cancer and heart diseases. Tomato is one of the most important sources of lycopene. The main information on the effect of environmental parameters on quality and health-retaining constituents of tomato fruit is mostly related to temperature (air- and fruit canopy temperature) and light effects that might provide a stress to the fruit. Nowadays little is know about the direct effect of elevated CO2.The aim of the present work was to evaluate the effects of elevated CO2 in Perspex open top chambers (OTC) on the lycopene content of tomato fruit.Experiments on the effects of elevated CO2 concentrations showed mixed results. In this work it was found that concentrations of lycopene in a fruit decreased significantly when elevated CO2 was used. Elevated nitrogen sources generated only slight, but not significant difference in the lycopene concentration of tomato fruit

Long-term response of the nematode community to elevated atmospheric CO2 in a temperate dry grassland soil

Long-term effects of the elevated atmospheric CO2 on biosphere have been in focus of research since the last few decades. In this experiment undisturbed soil monoliths of loess grassland were exposed to an elevated CO2 environment (two-times the ambient CO2 level) for a period of six years with the aid of the open top chamber method. Control without a chamber and CO2 elevation was applied as well. Elevated CO2 level had very little impact on soil food web. It did not influence either root and microbial biomass or microbial and nematode community structure. The only significant response was that density of the bacterial feeder genus Heterocephalobus increased in the chamber with elevated CO2 concentration. Application of the open top chambers initiated more changes on nematodes than the elevated CO2 level. Open top chamber (OTC) method decreased nematode density (total and plant feeder as well) to less than half of the original level. Negative effect was found on the genus level in the case of fungal feeder Aphelenchoides , plant feeder Helicotylenchus and Paratylenchus . It is very likely that the significantly lower belowground root biomass and partly its decreased quality reflected by the increased C/N ratio are the main responsible factors for the lower density of the plant feeder nematodes in the plots of chambers. According to diversity profiles, MI and MI(2–5) parameters, nematode communities in the open top chambers (both on ambient and elevated CO2 level) seem to be more structured than those under normal circumstances six years after start of the experiment

Elevated CO2 affects the content of glomalin related soil protein in xeric temperate loess and temperate semi-desert sand grasslands

Monoliths of temperate loess grassland and temperate semi-desert sand grassland have been exposed to elevated CO2 (700 μmol mol-1 ) and present ambient CO2 concentration in a 6-year open top chamber (OTC) experiment. In loess grassland elevated CO2 increased both biomass and vegetation cover, whereas there was no similar effect found in semi-desert grassland. The content of glomalin related soil protein (GRSP) increased in both loess and sand grasslands under CO2 enrichment (early summer aspect). The increase was higher in the case of easily extractable fraction (EEG), representing 14.7 and 22.2% of the chambered control’s EEG, for loess and sand grassland respectively. In the case of total glomalin the increase was much lower 7.9% (loess) and 2.6% (sand). On the basis of differences between elevated and ambient CO2 treatment we could conclude that elevated CO2 promoted C-deposition in xeric temperate grassland in early summer. Increases of EEG indicate an efficient partitioning of the recently fixed carbon to the soil