Investigating the cores of fossil systems with Chandra

We investigate the cores of fossil galaxy groups and clusters (`fossil systems') using archival Chandra data for a sample of 17 fossil systems. We determined the cool-core fraction for fossils via three observable diagnostics, the central cooling time, cuspiness, and concentration parameter. We quantified the dynamical state of the fossils by the X-ray peak/brightest cluster galaxy (BCG), and the X-ray peak/emission weighted centre separations. We studied the X-ray emission coincident with the BCG to detect the presence of potential thermal coronae. A deprojection analysis was performed for z < 0.05 fossils to obtain cooling time and entropy profiles, and to resolve subtle temperature structures. We investigated the Lx-T relation for fossils from the 400d catalogue to see if the scaling relation deviates from that of other groups. Most fossils are identified as cool-core objects via at least two cool-core diagnostics. All fossils have their dominant elliptical galaxy within 50 kpc of the X-ray peak, and most also have the emission weighted centre within that distance. We do not see clear indications of a X-ray corona associated with the BCG unlike that has been observed for some other objects. Fossils do not have universal temperature profiles, with some low-temperature objects lacking features that are expected for ostensibly relaxed objects with a cool-core. The entropy profiles of the z < 0.05 fossil systems can be well-described by a power law model, albeit with indices smaller than 1. The 400d fossils Lx-T relation shows indications of an elevated normalisation with respect to other groups, which seems to persist even after factoring in selection effects.Comment: Accepted for publication in Astronomy and Astrophysic

The Antecedents of Information Systems Development Capability in Firms: A Knowledge Integration Perspective

The linkages between IS and business units are recognized as being critical to information systems development processes and outcomes. Previous research has found that they are associated with better performing ISD teams, stronger alignment between firms’ IT investments and business objectives, and comparatively superior exploitation of information technologies for business ends. What remains lacking in this stream is a coherent theoretical explanation for why and how the linkages between the IS unit and business units in a firm influence ISD processes and outcomes. This study draws on strength-of-ties theory to develop and test a project-level model that links both structural and cognitive IS-business linkages to ISD outcomes and processes. The key premise of this model is that IS-business linkages influence ISD primarily by facilitating integration of business and technical knowledge dispersed across internal business functions and outside the formal boundaries of the firm during the ISD process. Such integration of internal and external knowledge in turn influences ISD processes and outcomes. We tested the model using data on 133 projects collected from CIOs and client-side managers in 133 firms. Our results provide strong support for the hypothesized model

Scoping technology options for India's oil security: Part I - ethanol for petrol

Crude oil prices recently crossed US$ 75/bbl, fuelling serious concerns whether India's rapidly expanding economy can sustain a high and growing level of crude imports. There are also serious concerns of global warming from burning of fossil fuels. It may be time for India to explore options which can substitute petrol and diesel and are climate-friendly. In a series of two articles, we examine a few such technology and policy options. Part I focus on options for substituting petrol by ethanol from sugarcane: molasses, sugarcane juice and cellulose (bagasse). Part II analyses options for diesel substitution: Fischer-Tropsch liquids from coal, and bio-diesel from oil-bearing plants like jatropha

Scoping technology options for India's oil security: Part II - Coal to liquids and bio-diesel

India's diesel consumption is several times that of petrol. In this article, we examine two options for meeting India"s diesel demand: coal to liquids and bio-diesel. Coal gasification, followed by Fischer- Tropsch (FT) synthesis offers an opportunity for large-scale production of diesel as proven by South Africa, and now being attempted by China and Qatar. India could consider this option given its large coal reserves. Four such plants consuming 60-76 million tonnes (mt) coal per annum can generate 12 mt of FT liquid, which is 20% of the expected diesel demand in 2011-12. This would require an investment of about Rs 54,000-90,000 crores. FT synthesis is a proven technology, coal prices are relatively stable and land requirements are modest. However, coal supply and transportation could be a concern and the process increases India's CO2 emissions by about 80 mt. Oil-bearing plants such as jatropha, palm and sunflower can be cultivated on wastelands to produce bio-diesel. This option has several advantages: it can be integrated with the rural economy, almost CO2 neutral and a large employment generation potential. However, it is a mammoth undertaking requiring an investment of about Rs 45,000-58,000 crores. We also briefly discuss the potential of energy conservation using gasoline-hybrid cars, which can potentially increase fuel efficiency up to 200 miles per gallon

Guided Missile with an Intelligent Agent

Guided missiles involve the use of a conventional deviated pursuit course like proportionalnavigation algorithm and its variants, which is optimal when the speed advantage of the guided missile is veryhighandthe target maneouvering is minimal. Against the present-day aircraft,whichemploys fly-by-wire technology for high maneouverability andhigh speed, missiles needto have amuchhigher speed advantage or to use a combination of artificial intelligence and modern controlalgorithms. Results of simulation of pursuit and evasion with an autonomous intelligent agentincorporated in the control loop are presented

Neurosteroids: current perspective in therapy of neuropsychiatric disorders

Neurosteroids are natural or synthetic steroid derivatives which act locally in brain by modulating neuronal excitability. The objective of this study is to analyze available literature on classification, biosynthesis and mechanism of action, and therapeutic potential of neurosteroids. A review of literature pertaining to neurosteroids published from inception to 2018 was carried on data bases like PUBMED, Google Scholar and Science Direct. The search terms used were neurosteroids, neuro-active steroids, ganaxolone and GABA-A receptor modulators. Review of literature suggests neurosteroids are powerful neuro-modulators, involving rapid non-genomic and non-hormone receptor mechanisms. They are classified based on structure as pregnane, androstane and sulphated neurosteroids, and based on function as excitatory or inhibitory neurosteroids. They act via GABAA receptor (primarily), rho- GABA (ρGABA), NMDA-glutamate and sigma receptor modulation. The inhibitory neurosteroids demonstrate sedative, anxiolytic and anticonvulsant actions, whereas the excitatory agents produce memory enhancing and anxiogenic effects. They show efficacy in various CNS and psychiatric conditions like epilepsy, anxiety, depression, learning and memory disorders and substance abuse. Endogenous neurosteroids have limited clinical use due to low bioavailability, lack of specificity and unwanted effects. Hence, synthetic agents like alphaxalone, ganaxolone, sepranolone and brexanolone which have better bioavailability and specificity, are being investigated in various phases of clinical trials. Neurosteroids are novel endogenous compounds with neuro-modulatory function and show promising effects in therapy of various neurological and psychiatric conditions. Further studies that prove their long term efficacy and safety may revolutionize the clinical approach to therapy of these conditions