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

The line transect method for estimating densities of large mammals in a tropical deciduous forest: An evaluation of models and field experiments

We have evaluated techniques of estimating animal density through direct counts using line transects during 1988-92 in the tropical deciduous forests of Mudumalui Sanctuary in southern India for four species of large herbivorous mammals, namely, chital (Axis axis). sambar (Cervus unicolor). Asian elephant (Elephas maximus) and gaur (Bos gaurus) Density estimates derived from the Fourier Series and the Half-Normal models consistently had the lowest coefficient of variation. These two models also generated similar mean density estimates. For the Fourier Series estimator, appropriate cut-off widths for analyzing line transect data for the four species are suggested. Grouping data into various distance classes did not produce any appreciable differences in estimates of mean density or their variances, although model fit is generally better when data arc placed in fewer groups. The sampling effort needed to achieve a desired precision (coefficient of variation) in the density estimate is derived. A sampling effort of 800 km of transects returned a 10% coefficient of variation on estimate for ehital; for the other species a higher effort was needed to achieve this level of precision. There was no statistically significant relationship between detectability of a group and the size of the group for any species. Density estimates along roads were generally significantly different from those in the interior of the forest, indicating that road-side counts many not be appropriate for most species

An Effective Sentence Ordering Approach For Multi-Document Summarization Using Text Entailment

With the rapid development of modern technology electronically available textual information has increased to a considerable amount. Summarization of textual inform ation manually from unstructured text sources creates overhead to the user, therefore a systematic approach is required. Summarization is an approach that focuses on providing the user with a condensed version of the origina l text but in real time applicat ions extended document summarization is required for summarizing the text from multiple documents. The main focus of multi - document summarization is sentence ordering and ranking that arranges the collected sentences from multiple document in order to gene rate a well - organized summary. The improper order of extracted sentences significantly degrades readability and understandability of the summary. The existing system does multi document summarization by combining several preference measures such as chronology, probabilistic, precedence, succession, topical closeness experts to calculate the preference value between sentences. These approach to sent ence ordering and ranking does not address context based similarity measure between sentences which is very ess ential for effective summarization. The proposed system addresses this issues through textual entailment expert system. This approach builds an entailment model which incorpo rates the cause and effect between sentences in the documents using the symmetric measure such as cosine similarity and non - symmetric measures such as unigram match, bigram match, longest common sub - sequence, skip gram match, stemming. The proposed system is efficient in providing user with a contextual summary which significantly impro ves the readability and understandability of the final coherent summa

Gelation mechanism of thermoreversible poly(vinylidene fluoride) gels in glyceryl tributyrate

Poly(vinylidene fluoride) (PVF2) gels in glyceryl tributyrate (GTB) with fibrillar morphology in the dried state. The gels are transparent and WAXS results indicate the presence of α-phase PVF2 crystals in the gels. The gelation rate (t-1gel) has been measured by the test tube tilting method and has been analysed with the equation t-1gel ∝ f(c)f(T), where f(c) = concentration function and f(T) = temperature function. At a fixed temperature, the variation of t-1gel with concentration suggests that the nature of the connectedness in this system obeys the three dimensional percolation mechanism. On the other hand, at a fixed concentration, the variation of the gelation rate with temperature suggests that the gelation is a two step concerted process of conformational ordering and crystallization, the former acting as the rate determining step. The formation of fibrillar gels in this system has been attributed to the solvation of the TGTG conformer of PVF2 through compound formation in a 3:1 molar ratio of the monomeric units of PVF2 and GTB

The potential link between corporate innovations and corporate competitiveness:Evidence from IT firms in the UK

Purpose: The purpose of this paper is to provide a thorough empirical investigation of the potential link between corporate innovations and corporate competitiveness in the context of the UK IT industry. Design/methodology/approach: This research uses a panel of 216 UK IT firms for the period from 2000 to 2016. The sample data for this study were extracted from the Worldscope, extracted from the Datastream database from Thomson Reuters. For the analysis of the data, the generalised method of moments model is applied. Findings: The results of this study provide empirical evidence that there exists a strong, positive link between corporate innovations and corporate competitiveness. Such evidence further reinforces the common view in the current literature of strategic management that because of the nature of their business, firms in the IT industry need to enhance their innovative capacities on a continual basis because of their critical role on these firms’ success and survival. Also, it is found that when the proxies for corporate innovations are lagged by two periods, their impact on corporate competitiveness becomes relatively more significant. However, when they are further lagged, i.e. by three periods, such an impact turns out to be relatively less pronounced. Research limitations/implications: The data gathered for this paper was restricted to IT-oriented firms in the UK. Using a secondary database (Datastream), the paper considered the period of 2000-2016. Originality/value: The research makes a significant contribution to the current debate on the relationship between information technology, innovation and performance, referred to in the literature as the productivity paradox, by studying the problem in the IT industry. It supports organisations from the sector in their efforts to deal with the dynamic nature of technological innovations and of the context where they operate. Methodologically, the way the study has measured the concepts of innovation and performance and the lessons learned from their analysis has also brought value to the research

COMPARATIVE STUDY ON CHARAKA NIDANA STHANA WITH OTHER CLASSICS

Among all the available classics, the most ancient representative of Kaya Chikitsa is Charaka Samhita. It is not only a text book it is an ideal ancient treatise based on eternal fundamentals and basic principles. Charaka Samhita consists of eight diseases in Nidana Sthana. All the classics gives importance to Nidana because it is a Sarva Tantra Siddantha that, the effect will always going to imitate the cause i.e. Karya Karana Bhava. Before understanding Chikitsa the knowledge of nidana is very necessary and for all disease. The main line of treatment is Nidana parivarjana and to get the clear knowledge of disease one should know about the Nidana panchaka, which is explained in Nidana sthana. Diagnosis is never complete without the elicitation of all the factors associated with the diseases. Aims and Objectives: To enlighten the basic concept of framework of Nidana sthana to its full perspective and the importance to the specific concept as well as the number of chapter given in Nidana sthana. Materials and Methods: In this study classical Ayurveda text were thoroughly studied where the compilation has been done. Discussion: compiled all the information of Nidana sthana and critically analysed in aspect of content and chapters of each Nidana sthana of different classics. Elicitation of Nidana is necessary for the proper identification of Dosha, the Roga, Rogavasta, Roga Bala, and Sadhya Asadhya. Result: Charaka nidana sthana is provides the basic fundamental concept to all other classics. Nidana sthana gives the draft of many pathogenesis. The other classics elaborated the Nidana panchaka concept in very detail manner

Structural chemistry and membrane modifying activity of the fungal polypeptides zervamicins, antiamoebins and efrapeptins

The fungal polypeptides zervamicins, antiamoebins and efrapeptins have been fractionated into several polypeptide components by HPLC. A zervamicin fraction lacking tryptophan has been characterized and shown to possess an N-terminal leucine residue. The conformations of zervamicin IIA and a synthetic analog in solution are compared with those determined for the related peptide, antiamoebin. The results are consistent with a completely helical structure for the apolar analog of zervamicin in chloroform, with partial unfolding in dimethylsulfoxide. A similar conformation has been determined for natural zervamicin IIB. A synthetic analog of efrapeptin forms a continuous helix in apolar solvents while, partial unfolding is seen in polar solvents. Natural zervamicin is an effective uncoupler of mitochondrial oxidative phosphorylation. Significant differences in membrane modifying activity are noted for the natural peptide and the synthetic apolar analog of zervamicin

Credit-Based Congestion Pricing: Expert Expectations and Guidelines for Application

Congestion pricing (CP) ensures that travelers recognize the true travel-time costs of their trip- making by accounting for the cost of delays imposed on fellow road users. Credit-based congestion pricing (CBCP) is a novel strategy which seeks to overcome the negative equity impacts of CP by allocating monthly budgets to eligible travelers to spend on congestion tolls. Previous works on CBCP have surveyed public opinion and examined the traffic and travel-welfare impacts of an Austin, Texas, application. This paper develops the CBCP policy further, examining expert opinions and system cost prediction. Transport economists, toll technology experts, administrators, policymakers, and commercial interests were surveyed for feedback on credit distribution, revenue uses, public reaction, appropriate technology and configuration, enforcement issues, and system-wide economic, land use, and business impacts. The results of this work are detailed recommendations for CBCP implementation, including estimates of administrative and technology costs for implementation of a CBCP policy in the Austin region