180 research outputs found
Identification of rice blast disease-suppressing bacterial strains from the rhizosphere of rice grown in Pakistan.
Sixteen bacterial strains isolated from the roots and rhizosphere of rice plants growing in saline and non-saline soils from the Shorkot area of Pakistan were tested for their ability to promote plant growth and reduce the incidence of rice blast disease. When applied to the soil, many of the isolated rhizobacterial strains increased seedling growth and/or suppressed rice blast disease in greenhouse-grown plants of the cultivars Super Basmati and Azucena, but each cultivar responded to different subsets of the bacteria. In the cv Super Basmati, increased blast resistance was correlated with the production of siderophores by the rhizobacteria. Several strains inhibited the growth of the causative agent of rice blast disease, the fungal pathogen Magnaporthe grisea, in an in vitro dual culture assay. Direct bioantagonism was correlated with disease resistance in Super Basmati, but not in Azucena, and direct antagonism as a cause for the reduced disease incidence is also unlikely since no epiphytic colonisation of leaves was detected. Rhizosphere colonisation by the bacteria in plants grown in sterile sand was correlated with disease resistance in Super Basmati, but not in Azucena. As well as the differences in strains that protected each cv against blast disease, we also found that there were differences in the ability of some strains to protect plants against blast depending on soil type. Hence, there are complex interactions between rhizobacteria and rice plants with respect to biocontrol of rice blast disease, dependent upon both rice cv and soil type. The identity of strains that promoted high levels of disease protection, including three that performed well across all plant cultivars and growth conditions, was determined by 16S rRNA gene sequencing
p-GaAs nanowire MESFETs with near-thermal limit gating
Difficulties in obtaining high-performance p-type transistors and gate
insulator charge-trapping effects present two major challenges for III-V
complementary metal-oxide semiconductor (CMOS) electronics. We report a p-GaAs
nanowire metal-semiconductor field-effect transistor (MESFET) that eliminates
the need for a gate insulator by exploiting the Schottky barrier at the
metal-GaAs interface. Our device beats the best-performing p-GaSb nanowire
metal-oxide-semiconductor field effect transistor (MOSFET), giving a typical
sub-threshold swing of 62 mV/dec, within 4% of the thermal limit, on-off ratio
, on-resistance ~700 k, contact resistance ~30 k,
peak transconductance 1.2 S/m and high-fidelity ac operation at
frequencies up to 10 kHz. The device consists of a GaAs nanowire with an
undoped core and heavily Be-doped shell. We carefully etch back the nanowire at
the gate locations to obtain Schottky-barrier insulated gates whilst leaving
the doped shell intact at the contacts to obtain low contact resistance. Our
device opens a path to all-GaAs nanowire MESFET complementary circuits with
simplified fabrication and improved performance
The Existence of Einstein Static Universes and their Stability in Fourth order Theories of Gravity
We investigate whether or not an Einstein Static universe is a solution to
the cosmological equations in gravity. It is found that only one class
of theories admits an Einstein Static model, and that this class is
neutrally stable with respect to vector and tensor perturbations for all
equations of state on all scales. Scalar perturbations are only stable on all
scales if the matter fluid equation of state satisfies
. This result is remarkably similar to
the GR case, where it was found that the Einstein Static model is stable for
.Comment: Minor changes, To appear in PR
Large-scale perturbations on the brane and the isotropy of the cosmological singularity
We present the complete set of propagation and constraint equations for the
kinematic and non-local first order quantities which describe general linear
inhomogeneous and anisotropic perturbations of a flat FRW braneworld with
vanishing cosmological constant and decompose them in the standard way into
their scalar, vector and tensor contributions. A detailed analysis of the
perturbation dynamics is performed using dimensionless variables that are
specially tailored for the different regimes of interest; namely, the low
energy GR regime, the high energy regime and the dark energy regime. Tables are
presented for the evolution of all the physical quantities, making it easy to
do a detailed comparison of the past asymptotic behaviour of the perturbations
of these models. We find results that exactly match those obtained in the
analysis of the spatially inhomogeneous braneworld cosmologies
presented recently; i.e., that isotropization towards the model
occurs for .Comment: 13 pages, revtex
Modern Feedback System: A Survey
The Feedback given by the stake holders about the current state of performance of any organization is essential for its growth. It provides vital information, which can be used to improve performance. In this way it provides motivation and fuels the continual improvement process. In business, it helps to deliver the best customer experiences. It forms the backbone of success of any institution or individual. It also forms the crust of good supervision in any organization. Feedback system initially started with raising hands, saying yes or no, then it evolved into answering questions through feedback forms, suggestion boxes etc. With the evolution in internet technology, it has now changed into web based, app based feedback systems etc. This paper explains different feedback systems that are currently in use and also explains about advantages and disadvantages of these systems.
DOI: 10.17762/ijritcc2321-8169.16047
SUPPRESSION OF INCIDENCE OF RHIZOCTONIA SOLANI IN RICE BY SIDEROPHORE PRODUCING RHIZOBACTERIAL STRAINS BASED ON COMPETITION FOR IRON
Rice is a major crop in much of the developing world, where disease management using agrochemicals is not economically practical, nor environmentally safe. The identification of biocontrol agents therefore presents a useful alternative. Here, we screened bacterial strains isolated from the rhizosphere of rice plants, and identified a number of these that exhibit antagonistic activity towards the fungal pathogen, Rhizoctonia solani, the causative agent of rice sheath blight disease. Correlation analysis with different metabolites produced by these bacteria revealed that antagonism was strongly correlated with the quantity of siderophores produced by individual strains, and was increased under iron-limiting conditions. Selected high-siderophore-producing strains were found to promote the growth of rice plants, possibly via the solubilisation of soil phosphates, nitrogen fixation and the production of phytohormones. These same PGPR also conferred resistance against sheath blight disease, which resulted in significant yield increases in infected plants. A consortium of the selected strains was especially effective in both growth promotion and disease suppression, and generally performed better than treatment with the fungicide, benlate. Molecular analysis indicated that the PGPR strains tested enhance plant defence gene expression, and may therefore activate induced systemic resistance in rice. Our work has identified a series of rhizobacterial strains able to promote plant growth and provide effective resistance against sheath blight disease in rice and which therefore have potential for application as biocontrol agents in agriculture
SUPPRESSION OF INCIDENCE OF RHIZOCTONIA SOLANI IN RICE BY SIDEROPHORE PRODUCING RHIZOBACTERIAL STRAINS BASED ON COMPETITION FOR IRON
Rice is a major crop in much of the developing world, where disease management using agrochemicals is not economically practical, nor environmentally safe. The identification of biocontrol agents therefore presents a useful alternative. Here, we screened bacterial strains isolated from the rhizosphere of rice plants, and identified a number of these that exhibit antagonistic activity towards the fungal pathogen, Rhizoctonia solani, the causative agent of rice sheath blight disease. Correlation analysis with different metabolites produced by these bacteria revealed that antagonism was strongly correlated with the quantity of siderophores produced by individual strains, and was increased under iron-limiting conditions. Selected high-siderophore-producing strains were found to promote the growth of rice plants, possibly via the solubilisation of soil phosphates, nitrogen fixation and the production of phytohormones. These same PGPR also conferred resistance against sheath blight disease, which resulted in significant yield increases in infected plants. A consortium of the selected strains was especially effective in both growth promotion and disease suppression, and generally performed better than treatment with the fungicide, benlate. Molecular analysis indicated that the PGPR strains tested enhance plant defence gene expression, and may therefore activate induced systemic resistance in rice. Our work has identified a series of rhizobacterial strains able to promote plant growth and provide effective resistance against sheath blight disease in rice and which therefore have potential for application as biocontrol agents in agriculture
An age-dependent outcome analysis of microvascular decompression and percutaneous thermocoagulation in trigeminal neuralgia
BACKGROUND
Trigeminal neuralgia (TN) is a severe pain condition and the most common facial neuralgia. While microvascular decompression (MVD) presents an excellent treatment in neurovascular compression cases, percutaneous thermocoagulation (PT) of the ganglion Gasseri is an alternative option. This study aimed to evaluate post-operative complication rate and outcome of both treatment strategies related to the patient’s age.
METHODS
The medical records of all patients with the diagnosis of trigeminal neuralgia undergoing an MVD or PT of the ganglion Gasseri (between January 2007 and September 2017) were reviewed to determine the efficacy and the complication rate of both methods in regard to the patient’s age.
RESULTS
Seventy-nine patients underwent MVD surgery and 39 a PT. The mean age of patients in the MVD group was 61 years and 73 years in the PT group. There were 59 (50%) female patients. Nerve-vessel conflict could be identified in 78 (98.7%) MVD and 17 (43.6%) PT patients on preoperative MRI. Charlson comorbidity index was significantly higher in PT group (2.4 (1.8) versus 3.8 (1.8) p < 0.001). The Barrow pain score (BPS) at the last follow-up demonstrated higher scores after PT (p = 0.007). The complication rate was markedly higher in PT group, mostly due to the facial hypesthesia (84.6% versus 27.8%; p < 0.001). Mean symptom-free survival was significantly shorter in the PT group (9 vs. 26 months, p < 0.001). It remained statistically significant when stratified into age groups: (65 years and older: 9 vs. 18 months, p = 0.001).
Duration of symptoms (OR 1.005, 95% CI 1.000–1.010), primary procedure (OR 6.198, 95% CI 2.650–14.496), patient age (OR 1.033, 95% CI 1.002–1.066), and postoperative complication rate (OR 2.777, 95% CI 1.309–5.890) were associated with treatment failure.
CONCLUSION
In this patient series, the MVD is confirmed to be an excellent treatment option independent of patient’s age. However, while PT is an effective procedure, time to pain recurrence is shorter, and the favorable outcome (BPS 1 and 2) rate is lower compared to MVD. Hence MVD should be the preferred treatment and PT should remain an alternative in very selected cases when latter is not possible but not in the elderly patient per se
Braneworld Dynamics of Inflationary Cosmologies with Exponential Potentials
In this work we consider Randall-Sundrum braneworld type scenarios, in which
the spacetime is described by a five-dimensional manifold with matter fields
confined in a domain wall or three-brane. We present the results of a
systematic analysis, using dynamical systems techniques, of the qualitative
behaviour of Friedmann-Lemaitre-Robertson-Walker type models, whose matter is
described by a scalar field with an exponential potential. We construct the
state spaces for these models and discuss how their structure changes with
respect to the general-relativistic case, in particular, what new critical
points appear and their nature and the occurrence of bifurcation.Comment: 15 pages, 9 figures, RevTex 4. Submitted to Physical Review
Are braneworlds born isotropic?
It has recently been suggested that an isotropic singularity may be a generic
feature of brane cosmologies, even in the inhomogeneous case. Using the
covariant and gauge-invariant approach we present a detailed analysis of linear
perturbations of the isotropic model which is a past attractor in
the phase space of homogeneous Bianchi models on the brane. We find that for
matter with an equation of state parameter , the dimensionless
variables representing generic anisotropic and inhomogeneous perturbations
decay as , showing that the model is asymptotically stable
in the past. We conclude that brane universes are born with isotropy naturally
built-in, contrary to standard cosmology. The observed large-scale homogeneity
and isotropy of the universe can therefore be explained as a consequence of the
initial conditions if the brane-world paradigm represents a description of the
very early universe.Comment: Changed to match published versio
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