Orbital Transfer Vehicle (OTV) engine study. Phase A: Extension

An orbital transfer vehicle OTV engine study program was undertaken to provide additional expander and staged combustion cycle data in the design definition of the OTV engine. The proposed program effort optimizes the expander cycle engine concept (consistent with identified OTV engine requirements), investigates the feasibility of kitting the staged combustion cycle engine to provide extended low thrust operation, and conducts in-depth analysis of development risk, crew safety, and reliability for both cycles. Additional tasks to establish the cost of a 10K thrust expander cycle engine and to render support of OTV systems study contractors are reported

An Efficient Buffer Management Policy for DTN

AbstractDelay or Disruption Tolerant Networks (DTNs) are challenged networks where an end-to-end path may not always exist, due to which it is necessary to use a store-carry-forward paradigm for routing messages from source to destination. DTNs have emerged from MANETs, inheriting their typical properties like mobility, network partitioning, sparse network structure, etc., differing in the inability to use IP. Due to the high mobility of nodes, and limited radio transmission range, two nodes may not always be able to communicate with each other. Thus, communication is established with the help of encounter opportunities between nodes. So intelligent relay selection plays an important role in routing performance. But apart from relay selection, effective buffer management policies also have an impact on routing performance. In this paper we have discussed existing buffer management methods in literature and proposed a novel buffer management scheme based on hop-count and TTL, which uses partial network knowledge. Experimental results show that the proposed buffer management scheme outperforms existing buffer management policies in terms of higher delivery rate and lower overhead ratio

ALTERATIONS IN PROTEIN AND NUCLEIC ACID METABOLISM OF LYMPHOMA 6C3HED-OG CELLS IN MICE GIVEN GUINEA PIG SERUM

Lymphoma 6C3HED-OG cells, known from previous work to be susceptible to the effects of guinea pig serum in vivo and dependent upon extrinsic asparagine for protein synthesis and growth in vitro, remained for the most part morphologically intact and countable in the electronic cell counter following exposures of 1 and 2 hr to the effects of heated (56°C, 30 min) guinea pig serum injected into the peritoneal cavities of mice in which the lymphoma cells were growing rapidly; after exposures of 4 and 6 hr the bulk of the -OG cells remained still intact and countable in the cell counter, though by this time a small proportion of them (5 to 12%) proved stainable with eosin in wet preparations) hence were presumably nonviable. After 12, 16, and 24 hr of exposure, however, the bulk of the -OG cells were either lysed or fragmented, to the extent that they did not register in the cell counter. Morphologic studies of the cells exposed 16 and 24 hr to the effects of heated guinea pig serum in vivo, disclosed that most of the cells then remaining were either frankly necrotic or greatly altered otherwise, marked vacuolation of the cytoplasm being the most conspicuous alteration in cells not yet obviously necrotic. Long before the bulk of the Lymphoma 6C3HED-OG cells had become conspicuously changed morphologically following exposure to the effects of heated guinea pig serum in vivo, they manifested striking alterations in protein metabolism, as was disclosed by "pulse" studies with radioactive valine. For example, the protein metabolism of -OG cells, as measured by their incorporation of L-valine-C14, was sharply curtailed following 15 min of exposure to heated guinea pig serum in vivo, as compared with valine incorporation by cells labeled immediately after exposure to the guinea pig serum. Following exposure to heated guinea pig serum during 60 min, -OG cells incorporated less than half as much L-valine-C14 as did cells labeled immediately after exposure, and the incorporation of L-valine-C14 was still less after 120 min of exposure. By contrast, Lymphoma -RG1 cells, known from previous work to be wholly insusceptible to the effects of guinea pig serum in vivo and independent of need for extrinsic asparagine for protein synthesis and growth in vitro, showed no curtailment whatever of protein synthesis following exposures to the effects of heated guinea pig serum in vivo during periods of 15, 60, and 120 min. Reasons are given for considering the prompt inhibition of protein synthesis in the asparagine-dependent -OG cells a direct result of asparagine-deprivation induced in vivo by the injected guinea pig serum, the L-asparaginase of which presumably converted the available L-asparagine of the host to L-aspartic acid that was not taken up by the -OG cells. The synthesis of deoxyribonucleic acid by Lymphoma 6C3HED-OG cells, as measured by the incorporation of thymidme-H3, determined with the aid of liquid scintillation counting and autoradiography, was also altered by exposure of the lymphoma cells to the effects of heated guinea pig serum in vivo, though not during exposures of 15 and 60 min; only after an exposure of 120 min did the population of -OG cells incorporate notably less thymidine-H3 than did control populations, though after 240 min of exposure the -OG cells incorporated less than one-fifth as much tritiated thymidineas had -OG cells exposed to heated guinea pig serum for 60 min or to heated horse serum for periods up to 240 min. Autoradiographs indicated that DNA synthesis by -OG cells normally proceeds at an intense level that leads to some 60% of these cells being heavily labeled in autoradiographs at any given time; after exposure to the effects of heated guinea pig serum during 2 and 4 hr in vivo, however, the lymphoma cells lost their ability to incorporate enough tritiated thymidine to become heavily labeled, but approximately the same proportion of them (56 to 58%) retained their ability to incorporate sufficient tritiated thymidine to become lightly labeled. The possibility is considered that the inhibition of DNA synthesis in the asparagine-dependent -OG cells exposed to the effects of heated guinea pig serum in vivo may be secondary to the previously manifest inhibition of protein synthesis. Further, in tests of ribonucleic acid metabolism of Lymphoma 6C3HED-OG cells after exposure to the effects of heated guinea pig serum in vivo during periods of 15, 60, 120, and 240 min, the findings indicated that the ability of the lymphoma cells to synthesize RNA, as measured by their capacity to incorporate uridine-5-H3, remained unaltered during the exposures of 15, 60, and 120 min, but was substantially reduced following 240 min of exposure. The findings are considered in relation to the probability, disclosed in part by previous studies, that heated guinea pig serum brings about its effects upon Lymphoma 6C3HED-OG cells in vivo by providing active L-asparaginase in large amounts, which presumably converts the available (extracellular) asparagine of the host to aspartic acid, the latter not being taken up by the lymphoma cells in vivo or in vitro. Hence it seems likely that heated guinea pig serum in this way brings about a state of asparagine deprivation that is responsible for the sequential metabolic and morphologic alterations that become manifest in asparagine-dependent Lymphoma 6C3HED-OG cells following their exposure to the effects of guinea pig serum in vivo, as here described

Reverse Engineering of Computer Software and U.S. Antitrust Law

This article explores when efforts by firms to restrict reverse engineering of their software, and corresponding agreements by other firms not to reverse engineer this software, could raise significant antitrust issues. This article provides an overview of how the laws prohibiting certain acts of monopolization, attempted monopolization, refusals to deal, and tying might apply to restrictions and agreements concerning the reverse engineering of computer software. As a necessary predicate to this analysis, the article first briefly describes the contours of intellectual property protection for software, including the fair use and the copyright misuse doctrines

Shrinking labour geographies: Transport access for paid work in later ages

Background and objectives In developing countries, a substantial share of the older population is employed (WHO, 2007), which is anticipated to triple between 2020 and 2050, bolstered by the rise of bridge employment in later life. Bridge jobs are part-time, informal work arrangements that serve as a transitional phase between full-time employment and retirement. While transport access for older adults is a primary policy concern in the age-friendly cities framework, their experiences of encountering and negotiating labour geographies, particularly transport systems to access bridge employment, are understudied. Research design and methods This paper used a qualitative and interpretative approach to analyse how older adults engage in nonlinear work patterns and commute to workspaces. We use a combination of visual mapping, observations, and in-depth interviews with older adults in Bengaluru, an urban metropolis in southern India. Results Older workers engage in regular mobility routines to access informal bridge jobs. Our results suggest that the precarity of their bridge jobs permeates into their mobilities. Class, gender, and spatialities create additional layers of barriers to their already constrained transport resources. Economically disadvantaged older individuals encountered shrinking labour geographies due to unaffordable public transportation and first-and-last-mile journeys. For reasons of safety, older women were forced to depend on shared and public transport options, which were often unreliable. Lastly, older workers residing in geographically marginalised areas find more difficulty in organising transport to bridge jobs. Discussion and implications Bridge jobs in informal arrangements are important means of livelihood for older persons in countries like India. Apart from the already precarious working conditions, the weak systemic transport support induces strain on the working conditions of older workers. From the purview of labour geography, adding to the natural limits of ageing, induced limits such as ageism and precarity at workplaces and non-age-friendly transport infrastructure create situations of vulnerable employment among older adults in the cities of the Global South