15,825 research outputs found
Signatures of extra dimensions in gravitational waves
Considering gravitational waves propagating on the most general
4+N-dimensional space-time, we investigate the effects due to the N extra
dimensions on the four-dimensional waves. All wave equations are derived in
general and discussed. On Minkowski4 times an arbitrary Ricci-flat compact
manifold, we find: a massless wave with an additional polarization, the
breathing mode, and extra waves with high frequencies fixed by Kaluza-Klein
masses. We discuss whether these two effects could be observed.Comment: v1: 21 pages + appendices, comments welcome! v2: few minor additions;
v3: minor mistake corrected in the warped case, no impact on the main
results, appendix A.2 modifie
Synthesis and study of biological activity of tetrahydro-1H-[3]-benzazepines
The 3-Benzazepines are an important class of compounds in drug discovery due to their biological activity such as analgesic, antihypertensive or anticancer properties as well as dopaminergic or antidopaminergic activity. In particular, the tetrahydro-1H-[3]- benzazepine is a common skeleton in a number of natural and pharmaceutical products. As consequence of the interesting biological properties, derivatives of the tetrahydro-1H-[3]-benzazepines, especially the 1-aryl substituted have been synthesized by different routes and evaluated their pharmacologic activity. [1,2]
The stereoselective synthetic approaches of tetrahydro-1H-[3]-benzazepine have focused on ring enlargements, as the Stevens rearrangement (SR) which is a good regio- and diastereoselective synthetic methodology. In my research group, the reaction conditions to synthesize tetrahydro-1H-[3]-benzazepines 1,2-disubstituted by via SR from tetrahydroisoquinolinium salts conveniently functionalized have been optimized. [3,4]
This methodology allowed us to obtain a wide variety of tetrahydro-1H-[3]- benzazepines 1,2-disubstituted with different substituents at A-ring (Cl, OMe) and the C-1 (-C6H4X, X = H, OMe, Cl, NO2, NMe2, NH2, SMe) and C-2 (Electron-withdrawing groups) positions. The demethylation of the synthesized tetrahydroisoquinolines and tetrahydro-1H-[3]-benzazepines 1,2-disubstituted, lead us to get catechol structure, an important requirement for their dopaminergic activity.
We have studied the dopaminergic activity of the synthesized compounds by radioligand binding assays, establishing a structure-activity relationships.
Literature:
[1] A. Gini, Adv. Synth. Catal. 2016, 358, 4049. [2] H. Damsen, Eur. J. Org. Chem.
2015, 36, 7880. [3] M. Valpuesta, Eur. J. Org. Chem. 2010, 23, 4393. [4] M. Ariza, Eur.
J. Org. Chem. 2011, 32, 6507.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Synthesis of bioactive compounds. Studies of their attachment to nanoparticles
The 1-aryl tetrahydroisoquinolines have attracted great attention in medicinal chemistry due to their biological activity. These compounds present antitumor, anti-HIV and antibacterial activities. Several analogues of 1-aryl tetrahydroisoquinoline are used for the treatment of neurodegenerative diseases such as Parkinson´s and Alzheimer´s diseases since also act as dopaminergic antagonists and N-methyl-D-aspartate receptor antagonist. [1]
The 1-substituted tetrahydro-3-benzazepines have also been studied for their affinity to the Phencylclidine binding site of the NMDA receptor as well as for their affinity to the dopaminergic receptors. [2]
In the last years, various methods have been carried out to satisfy the demand of novel tetrahydroisoquinolines and tetrahydro-3-benzazepines. We have synthesized nor-1-aryl tetrahydroisoquinolines with different substituents in the aryl group of C-1 (H, NMe2, SMe, NO2, NH2). In addition to this, we have performed the synthesis of nor-tetrahydro-3-benzazepinas by different routes, obtaining the best results via opening of epoxides by arylphenethylamines and subsequent cyclization.
The nor-tetrahydroisoquinolines and nor-tetrahydro-3-benzazepines have been derivatized to obtain appropiate adsorbates which can be attached to nanoparticles. This fact is crutial in drug delivery systems as well as in the improvement of the biocompatibility of these compounds.
Literature:
[1] Toshiaki Saitoh, Eur. J. Med. Chem. 2006, 41, 241. Mattias Ludwig, Eur. J. Med. 2006, 41, 1003. [2] Olaf Krull, Bioorg. Med. Chem. 2004, 12, 1439.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Causality Constraints on Massive Gravity
The de Rham-Gabadadze-Tolley massive gravity admits pp-wave backgrounds on
which linear fluctuations are shown to undergo time advances for all values of
the parameters. The perturbations may propagate in closed time-like curves
unless the parameter space is constrained to a line. These classical phenomena
take place well within the theory's validity regime.Comment: 6 pages, 4 figures; to appear in PR
Building a Social Accounting Matrix within the ESA95 Framework: Obtaining a Dataset for Applied General Equilibrium Modelling
This research provides a description of the process followed in order to assemble a Social Accounting Matrix for Spain corresponding to the year 2000 (SAMSP00). As argued in the paper, this process attempts to reconcile ESA95 conventions with requirements of applied general equilibrium modelling. Particularly, problems related to the level of aggregation of net taxation data, and to the valuation system used for expressing the monetary value of input-output transactions have deserved special attention. Since the adoption of ESA95 conventions, input-output transactions have been preferably valued at basic prices, which impose additional difficulties on modellers interested in computing applied general equilibrium models. This paper addresses these difficulties by developing a procedure that allows SAM-builders to change the valuation system of input-output transactions conveniently. In addition, this procedure produces new data related to net taxation information.input-output transactions, esa95 conventions, valuation system, net taxation on products, applied general equilibrium analysis, social accounting matrix
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