37 research outputs found
AdS Phase Transitions at finite \kappa
We investigate the effect of adding a Chern-Simons term coupled to an axion
field to SU(2) Einstein-Yang-Mills in a fixed /Schwarzschild background.
We show that, when the axion has no potential, there is a phase transition
between a Reissner-Nordstrom black-hole and one with a non-abelian condensate
as per the vanishing Chern-Simons case. Furthermore, by giving the axion field
a mass, one observes a phase transition between a Reissner-Nordstrom black-hole
with axion hair to a "superconducting" phase which also has a non-trivial axion
profile. We are able to perform a preliminary analysis for this interesting
case and observe that we can shift the critical temperature at which the phase
transition occurs and observe interesting features of the order parameter
scaling form.Comment: Version Published in JHE
Holographic Charged Fluid with Anomalous Current at Finite Cutoff Surface in Einstein-Maxwell Gravity
The holographic charged fluid with anomalous current in Einstein-Maxwell
gravity has been generalized from the infinite boundary to the finite cutoff
surface by using the gravity/fluid correspondence. After perturbing the boosted
Reissner-Nordstrom (RN)-AdS black brane solution of the Einstein-Maxwell
gravity with the Chern-Simons term, we obtain the first order perturbative
gravitational and Maxwell solutions, and calculate the stress tensor and
charged current of the dual fluid at finite cutoff surfaces which contains
undetermined parameters after demanding regularity condition at the future
horizon. We adopt the Dirichlet boundary condition and impose the Landau frame
to fix these parameters, finally obtain the dependence of transport
coefficients in the dual stress tensor and charged current on the arbitrary
radical cutoff . We find that the dual fluid is not conformal, but it has
vanishing bulk viscosity, and the shear viscosity to entropy density ratio is
universally . Other transport coefficients of the dual current turns
out to be cutoff-dependent. In particular, the chiral vortical conductivity
expressed in terms of thermodynamic quantities takes the same form as that of
the dual fluid at the asymptotic AdS boundary, and the chiral magnetic
conductivity receives a cutoff-dependent correction which vanishes at the
infinite boundary.Comment: 19 pages, v2: references added, v3: typos corrected, v5: typos
corrected, version accepted for publication in JHE
Maxwell-Chern-Simons Vortices and Holographic Superconductors
We investigate probe limit vortex solutions of a charged scalar field in
Einstein-Maxwell theory in 3+1 dimensions, for an asymptotically AdS
Schwarzschild black hole metric with the addition of an axionic coupling to the
Maxwell field. We show that the inclusion of such a term, together with a
suitable potential for the axion field, can induce an effective Chern-Simons
term on the 2+1 dimensional boundary. We obtain numerical solutions of the
equations of motion and find Maxwell-Chern-Simons like magnetic vortex
configurations, where the magnetic field profile varies with the size of the
effective Chern-Simons coupling. The axion field has a non-trivial profile
inside the AdS bulk but does not condense at spatial infinity.Comment: 17 pages, 5 figures, version accepted for publication in JHE
Non Abelian Tachyon Kinks
Starting from the action of two coincident non-BPS D9-branes, we investigate
kink configurations of the U(2) matrix tachyon field. We consider both Str and
Tr prescriptions for the trace over gauge indices of the non-BPS action.
Non-abelian tachyon condensation in the theory with Tr prescription, and the
resulting fluctuations about the kink profile, are shown to give rise to a
theory of two coincident BPS D8-branes. This is a natural non-abelian
generalization of Sen's mechanism of tachyon condensation on a single non-BPS
Dp-brane yielding a single BPS brane of codimesion one. By contrast, starting
with the Str gauge trace prescription of the coincident non-BPS D9-brane
action, such a generalization of Sen's mechanism appears problematic.Comment: 18 pages, references added, version to appear in JHE
Biodiversity, Ecology, and Secondary Metabolites Production of Endophytic Fungi Associated with Amaryllidaceae Crops
Amaryllidaceae family comprises many crops of high market potential for the food and pharmaceutical industries. Nowadays, the utilization of plants as a source of bioactive compounds requires the plant/endophytic microbiome interactions, which affect all aspects of crop’s quantity and quality. This review highlights the taxonomy, ecology, and bioactive chemicals synthesized by endophytic fungi isolated from plants of the Amaryllidaceae family with a focus on the detection of pharmaceutically valuable plant and fungi constituents. The fungal microbiome of Amaryllidaceae is species- and tissue-dependent, although dominating endophytes are ubiquitous and isolated worldwide from taxonomically different hosts. Root sections showed higher colonization as compared to bulbs and leaves through the adaptation of endophytic fungi to particular morphological and physiological conditions of the plant tissues. Fungal endophytes associated with Amaryllidaceae plants are a natural source of ecofriendly bioagents of unique activities, with special regard to those associated with Amarylloidae subfamily. The latter may be exploited as stimuli of alkaloids production in host tissues or can be used as a source of these compounds through in vitro synthesis. Endophytes also showed antagonistic potential against fungal, bacterial, and viral plant diseases and may find an application as alternatives to synthetic pesticides. Although Amaryllidaceae crops are cultivated worldwide and have great economic importance, the knowledge on their endophytic fungal communities and their biochemical potential has been neglected so far
Biodiversity, Ecology, and Secondary Metabolites Production of Endophytic Fungi Associated with Amaryllidaceae Crops
Amaryllidaceae family comprises many crops of high market potential for the food and pharmaceutical industries. Nowadays, the utilization of plants as a source of bioactive compounds requires the plant/endophytic microbiome interactions, which aect all aspects of cropâs quantity and quality. This review highlights the taxonomy, ecology, and bioactive chemicals synthesized by endophytic fungi isolated from plants of the Amaryllidaceae family with a focus on the detection of pharmaceutically valuable plant and fungi constituents. The fungal microbiome of Amaryllidaceae is species- and tissue-dependent, although dominating endophytes are ubiquitous and isolated worldwide from taxonomically dierent hosts. Root sections showed higher colonization as compared to bulbs and leaves through the adaptation of endophytic fungi to particular morphological and physiological conditions of the plant tissues. Fungal endophytes associated with Amaryllidaceae plants are a natural source of ecofriendly bioagents of unique activities, with special regard to those associated with Amarylloidae subfamily. The latter may be exploited as stimuli of alkaloids production in host tissues or can be used as a source of these compounds through in vitro synthesis. Endophytes also showed antagonistic potential against fungal, bacterial, and viral plant diseases and may find an application as alternatives to synthetic pesticides. Although Amaryllidaceae crops are cultivated worldwide and have great economic importance, the knowledge on their endophytic fungal communities and their biochemical potential has been neglected so far
InfluenĆŁa mulcirii Ći fertilizÄrii asupra culturii de conopidÄ timpurie
The purpose of the presentpaper is to evaluate the influence of mulching and fertilization on the early cauliflower crop. The research was carried out in the didactic and experimental field of the Vegetablegrowingdiscipline, at Agronomy UniversityIasi. The experimentwas of a bifactorial type, testingthe influence of mulching with three graduations (unmulched-Ct, mulching with polyethylene film of 15 and 30 ÎŒm in thickness) and of fertilization with four graduations (unfertilized-Ct, chemical fertilization, organic fertilization and application of microorganisms),under the conditions of 2018 and 2019. The cropwas established by usingseedlings of42 days, in strips of two rows, the distance between strips being of 80 cm and between rows of 60 cm. The distance between the plants in a row was of 25 cm, resulting in a density of about 57thousand plants per hectare. The results obtained demonstrate the necessity of mulching and fertilizing the early cauliflowercrop, the best yields being obtained in the case of the variant mulched with 30 ÎŒm foil and fertilized with chemical fertilizers