Arachidonic Acid as a Possible Negative Feedback Inhibitor of Nicotinic Acetylcholine Receptors on Neurons

Neuronal acetylcholine receptors, being highly permeable to calcium, are likely to regulate calcium-dependent events in neurons. Arachidonic acid is a membrane-permeant second messenger that can be released from membrane phospholipids by phospholipases in a calcium-dependent manner. We show here that activation of neuronal acetylcholine receptors triggers release of 3H-arachidonic acid in a calcium-dependent manner from neurons preloaded with the fatty acid. Moreover, low concentrations of arachidonic acid reversibly inhibit the receptors and act most efficiently on receptors likely to have the highest permeability to calcium, namely receptors containing α7 subunits. Low concentrations of arachidonic acid also reversibly inhibit α7- containing receptors expressed in Xenopus oocytes following injection of α7 cRNA. The oocyte results indicate following injection of α7 cRNA. The oocyte results indicate that the inhibition is a feature of the receptors rather than a consequence of neuron-specific machinery. The inhibition is not mediated by specific metabolites of arachidonic acid because the effects can be mimicked by other fatty acids; their effectiveness correlates with their content of double bonds. In contrast to arachidonic effects on calcium currents, inhibition of neuronal nicotinic receptors by the fatty acid cannot be prevented by blocking production of free radicals or by inhibiting protein kinase C. An alternative mechanism is that arachidonic acid binds directly to the receptors or perturbs the local environment in such a manner as to constrain receptor function

Memperkecil Kesenjangan Gender melalui Kebijakan Pengarusutamaan Gender (Pug)

Judul Buku : Negara dan Perempuan – Reorientasi Kebijakan PublikPengarang : Dr. Muhadjir M. Darwin, MPAPenerbit : Media Wacana Yogyakarta.Tahun Terbit : 2005Jumlah halaman : 313Buku “Negara dan Perempuan –Reorientasi Kebijakan Publik” merupakanhasil refleksi perhatian Penulis -yangditakdirkan berjenis kelamin laki-laki dalamwaktu yang panjang, yakni 13 tahun, melaluikedekatannya dengan tugas-tugas yang terkaitdengan issue (Penulis menggunakan kata„isu‟) gender

The weakly perturbed Schwarzschild lens in the strong deflection limit

We investigate the strong deflection limit of gravitational lensing by a Schwarzschild black hole embedded in an external gravitational field. The study of this model, analogous to the Chang & Refsdal lens in the weak deflection limit, is important to evaluate the gravitational perturbations on the relativistic images that appear in proximity of supermassive black holes hosted in galactic centers. By a simple dimensional argument, we prove that the tidal effect on the light ray propagation mainly occurs in the weak field region far away from the black hole and that the external perturbation can be treated as a weak field quadrupole term. We provide a description of relativistic critical curves and caustics and discuss the inversion of the lens mapping. Relativistic caustics are shifted and acquire a finite diamond shape. Sources inside the caustics produce four sequences of relativistic images. On the other hand, retro-lensing caustics are only shifted while remaining point-like to the lowest order.Comment: 12 pages, 1 figure

The Influence of Earnings Management, Audit Quality and CEO Duality on Tax Avoidance

This study a ims to get t h e empirical evidence about the influence ofearnings management, audit quality and CEO duality on the tax avoidance. Taxavoidance has used an effective tax rate (ETR) by calculating the corporate taxesexpenses divided by the earnings before income and tax during a certain period.Population of this research are the manufacturing companies in IndonesiaStock Exchange in 2014-2016 which 48 companies are using the purposive samplingtechnique. Methods of data analysis has applied the descriptive statistical analysisand multiple linear regression.These results have indicated that earnings management, audit quality andCEO duality have had a significant effect simultaneously on the tax avoidance.However, partial test results have shown that the audit quality and CEO dualityhave not affected the tax avoidance. While the earnings manegement has had asignificant effect on the tax avoidance

Darwin Meets Einstein: LISA Data Analysis Using Genetic Algorithms

This work presents the first application of the method of Genetic Algorithms (GAs) to data analysis for the Laser Interferometer Space Antenna (LISA). In the low frequency regime of the LISA band there are expected to be tens of thousands galactic binary systems that will be emitting gravitational waves detectable by LISA. The challenge of parameter extraction of such a large number of sources in the LISA data stream requires a search method that can efficiently explore the large parameter spaces involved. As signals of many of these sources will overlap, a global search method is desired. GAs represent such a global search method for parameter extraction of multiple overlapping sources in the LISA data stream. We find that GAs are able to correctly extract source parameters for overlapping sources. Several optimizations of a basic GA are presented with results derived from applications of the GA searches to simulated LISA data.Comment: 8 pages, 12 figure

When Organizational Pressures Collide – Balancing Information Security Risk Management and Compliance

Information Security Risk Management has found itself rising on the priority of organizations after the significant growth experienced by compliance activities in the last 20 years. This has led often to conflicts between the requirements of Information Security Risk Management and Compliance as said requirements could impact the same systems or compete from the same resources. This study identifies strategies and tactics that an organization might implement to address balancing the requirements of the two. Oliver (1991) Strategic Responses to Institutional Processes frame the strategies and tactics predicted by theory as well as inform what new insights can be derived from practice. A Children’s Hospital system serves as a setting to explore how the Information Systems and Compliance organizations navigate balancing Information Security Risk Management and Compliance requirements. A new tactic is identified that supplements those predicted by theory where Information Security Risk Management and Compliance requirements balancing is supported by formalized governance structures and processes

Scale-free networks are not robust under neutral evolution

Recently it has been shown that a large variety of different networks have power-law (scale-free) distributions of connectivities. We investigate the robustness of such a distribution in discrete threshold networks under neutral evolution. The guiding principle for this is robustness in the resulting phenotype. The numerical results show that a power-law distribution is not stable under such an evolution, and the network approaches a homogeneous form where the overall distribution of connectivities is given by a Poisson distribution.Comment: Submitted for publicatio

The Exchange Gate in Solid State Spin Quantum Computation: The Applicability of the Heisenberg Model

Solid state quantum computing proposals rely on adiabatic operations of the exchange gate among localized spins in nanostructures. We study corrections to the Heisenberg interaction between lateral semiconductor quantum dots in an external magnetic field. Using exact diagonalization we obtain the regime of validity of the adiabatic approximation. We also find qualitative corrections to the Heisenberg model at high magnetic fields and in looped arrays of spins. Looped geometries of localized spins generate flux dependent, multi-spin terms which go beyond the basic Heisenberg model.Comment: 13 pages, 8 figure

Exchange effects on electron scattering through a quantum dot embedded in a two-dimensional semiconductor structure

We have developed a theoretical method to study scattering processes of an incident electron through an N-electron quantum dot (QD) embedded in a two-dimensional (2D) semiconductor. The generalized Lippmann-Schwinger equations including the electron-electron exchange interaction in this system are solved for the continuum electron by using the method of continued fractions (MCF) combined with 2D partial-wave expansion technique. The method is applied to a one-electron QD case. Cross-sections are obtained for both the singlet and triplet couplings between the incident electron and the QD electron during the scattering. The total elastic cross-sections as well as the spin-flip scattering cross-sections resulting from the exchange potential are presented. Furthermore, inelastic scattering processes are also studied using a multichannel formalism of the MCF.Comment: 11 pages, 4 figure