1,608 research outputs found
A theoretical construction of wormhole supported by Phantom Energy
A new solution has been presented for the spherically symmetric space time
describing wormholes with Phantom Energy. The model suggests that the existence
of wormhole is supported by arbitrarily small quantity of Phantom Energy.Comment: 6 pages, One reference has been correcte
EV Hosting Capacity Enhancement in a Community Microgrid Through Dynamic Price Optimization-Based Demand Response
Community microgrids, as an emerging technology, offer resiliency in operation for smart grids. Microgrids are seeing an increased penetration of eco-friendly electric vehicles (EVs) in recent years. However, the uncontrolled charging of EVs can easily overwhelm such electric networks. In this work, we propose an efficient demand response (DR) scheme based on dynamic pricing to enhance the capacity of the microgrid to securely host a large number of EVs. A hierarchical two-level optimization framework is introduced to realize the DR scheme. At the upper level, the dynamic prices for the participating users in DR are optimized while at the lower level, each user optimizes its energy consumption based on the price signal from the upper level. An evolutionary algorithm and a mixed-integer linear programming model is employed to solve the upper and lower level problems, respectively. Energy scheduling problems of the users are solved in a distributed manner which adds to the scalability of the approach. The proposed DR scheme is tested on a microgrid system adopted from the IEEE European low-voltage distribution network. Numerical experiments confirm the effectiveness of the proposed DR scheme compared to the benchmark pricing policies from the literature
Medicinal formulations of a Kanda tribal healer – a tribe on the verge of disappearance in Bangladesh
The Kanda tribe is one of the lesser known small tribes of Bangladesh with an estimated population of about 1700 people (according to them), and on the verge of extinction as a separate entity. To some extent, they have assimilated with the surrounding mainstream Bengali-speaking population, but they still maintain their cultural practices including traditional medicinal practices, for which they have their own tribal healers. Nothing at all has been documented thus far about their traditional medicinal practices and formulations, which are on the verge of disappearance. The Kanda tribe can be found only in scattered tea gardens of Sreemangal in Sylhet district of Bangladesh; dispersion of the tribe into small separated communities isalso contributing to the fast losing of traditional medicinal practices. The objective of the present study was to conduct an ethnomedicinal survey among the traditional healers of the Kanda tribe (in fact, only one such healer was found after extensive searches). Information was collected from the healer with the help of a semi-structured questionnaire and the guided field-walk method. A total of 24 formulations were obtained from the healer containing 34 plants including two plants, which could not beidentified. Besides medicinal plants, the Kanda healer also used the body hairs of the Asiatic black bear (Ursus thibetanus) and bats (Pteropus giganteus giganteus) in one of his formulation for treatment of fever with shivering. The ailments treated by the Kanda healer were fairly common ailments like cuts and wounds, skin diseases, helminthiasis, fever, respiratory problems (coughs, asthma), gastrointestinal disorders (stomach pain, constipation, diarrhea), burning sensations during urination, various types of pain (headache, body ache, toothache, ear ache), conjunctivitis, poisonous snake, insect or reptile bites, jaundice, andbone fractures. A number of important drugs in allopathic medicine like quinine, artemisinin, and morphine (to name only a few) have been discovered from observing indigenous medicinal practices. From that view point, the formulations used by the Kanda healer merit scientific studies for their potential in the discovery of cheap and effective new drugs. Scientific validation of the medicinal formulations of the Kanda healer can also be effective for treatment of ailments among this tribe, which does not have or does not want to have any contact with modern medicine
Polypropylene fibre reinforced cement mortars containing rice husk ash and nano-alumina
This paper presents the effects of incorporating two supplementary cementitious materials: rice husk ash (RHA) and nano-alumina (NA) in polypropylene fiber (PPF) reinforced cement mortars. RHA is an agricultural waste material and thus recycling of this material has substantial economic and environmental benefits. Compressive strength, flexural strength, water absorption and drying shrinkage of the hardened composites were investigated. The interfacial transition zone and the microstructures were studied by using scanning electron micrograph (SEM) and X-ray diffraction (XRD) analysis. A slight increase in compressive strength of mortar was observed by using up to 10 wt% of RHA as a replacement of cement. However, addition of nano-alumina helped the compressive strength of mortar remain approximately equal to that of the control specimen even when 20 or 30 wt% RHA was used. Addition of polypropylene fibers resulted in significant increase in the flexural strength of the mortar specimens. It was also observed that NA and PPF could reduce water absorption by pore blocking effect. The positive interactions between polypropylene fibers and RHA resulted in the lowest drying shrinkage of the fibrous mortar containing RHA. XRD analysis showed that the intensity of Alite and Belite phases decreased and new peak of portlandite produced with the addition of NA. The addition of RHA enhanced the late strength of the cement composites. Consequently, the combined addition of RHA, NA and PPF has resulted in increasing of flexural strength and reduction in both water absorption and drying shrinkage of mortars
Composition, antioxidant and chemotherapeutic properties of the essential oils from two Origanum species growing in Pakistan
The GC-MS analyses of Origanum majorana L. (OME) and Origanum vulgare L. (OVE), Lamiaceae, essential oils helped identification of 39 (96.4% of the total oils) and 43 (92.9% of the total oils) components, respectively. The major constituents of OME were terpinene-4-ol (20.9%), linalool (15.7%), linalyl-acetate (13.9%), limonene (13.4%) and α-terpineol (8.57%), whereas, thymol (21.6%), carvacrol (18.8%), o-cymene (13.5%) and α-terpineol (8.57%) were the main components of OVE. In the disc diffusion and the resazurin microtitre assays, OME showed better antibacterial activity than OVE with larger zones of inhibition (16.5-27.0 mm) and smaller MIC (40.9-1250.3 μg/mL) against the tested bacterial strains. Only OVE displayed anti-heme biocrystallization activity with an IC50 at 0.04 mg/mL. In the DPPH assay, OVE showed better radical-scavenging activity than OME (IC50=65.5 versus 89.2 μg/mL) and both OME and OVE inhibited lionleic acid oxidation. However, in the bleaching β-carotene assay, OVE exhibited better antioxidant activity than OME. In the MTT assay, OME was more cytotoxic than OVE against different cancer cell types, such as MCF-7, LNCaP and NIH-3T3, with IC50s of 70.0, 85.3 and 300.5 μg/mL, respectively. Overall, some components of OME and OVE may have antiparasitic and chemotherapeutic activity
Madangones A and B, two new neolignans from Beilschmiedia madang Blume and their bioactivities
Two new neolignans, madangones A (1) and B (2), together with (+)-kunstlerone (3), vanillin, vanillic acid, betulin, β-sitosterol and β-sitostenone, were isolated from the stem bark of Beilschmiedia madang (Lauraceae). The structures of the compounds were determined by spectroscopic means. The compounds were tested for antioxidant, acetylcholinesterase inhibitory and anti-inflammatory activities. Compound (3) displayed the strongest DPPH radical-scavenging activity with an IC50 value of 68.7 M. Compound (2) exhibited the highest level of activity on the COX-2 model and acetylcholinesterase inhibition assay, with IC50 values of 27.4 and 70.3 µM, respectively
Thermodynamic instabilities in one dimensional particle lattices: a finite-size scaling approach
One-dimensional thermodynamic instabilities are phase transitions not
prohibited by Landau's argument, because the energy of the domain wall (DW)
which separates the two phases is infinite. Whether they actually occur in a
given system of particles must be demonstrated on a case-by-case basis by
examining the (non-) analyticity properties of the corresponding transfer
integral (TI) equation. The present note deals with the generic Peyrard-Bishop
model of DNA denaturation. In the absence of exact statements about the
spectrum of the singular TI equation, I use Gauss-Hermite quadratures to
achieve a single-parameter-controlled approach to rounding effects; this allows
me to employ finite-size scaling concepts in order to demonstrate that a phase
transition occurs and to derive the critical exponents.Comment: 5 pages, 6 figures, subm. to Phys. Rev.
The high-affinity binding site for tricyclic antidepressants resides in the outer vestibule of the serotonin transporter
The structure of the bacterial leucine transporter from Aquifex aeolicus (LeuT(Aa)) has been used as a model for mammalian Na+/Cl--dependent transporters, in particular the serotonin transporter (SERT). The crystal structure of LeuT(Aa) liganded to tricyclic antidepressants predicts simultaneous binding of inhibitor and substrate. This is incompatible with the mutually competitive inhibition of substrates and inhibitors of SERT. We explored the binding modes of tricyclic antidepressants by homology modeling and docking studies. Two approaches were used subsequently to differentiate between three clusters of potential docking poses: 1) a diagnostic SERTY95F mutation, which greatly reduced the affinity for [H-3] imipramine but did not affect substrate binding; 2) competition binding experiments in the presence and absence of carbamazepine (i.e., a tricyclic imipramine analog with a short side chain that competes with [3H] imipramine binding to SERT). Binding of releasers (para-chloroamphetamine, methylene-dioxy-methamphetamine/ecstasy) and of carbamazepine were mutually exclusive, but Dixon plots generated in the presence of carbamazepine yielded intersecting lines for serotonin, MPP+, paroxetine, and ibogaine. These observations are consistent with a model, in which 1) the tricyclic ring is docked into the outer vestibule and the dimethyl-aminopropyl side chain points to the substrate binding site; 2) binding of amphetamines creates a structural change in the inner and outer vestibule that precludes docking of the tricyclic ring; 3) simultaneous binding of ibogaine (which binds to the inward-facing conformation) and of carbamazepine is indicative of a second binding site in the inner vestibule, consistent with the pseudosymmetric fold of monoamine transporters. This may be the second low-affinity binding site for antidepressants
- …