253 research outputs found
Characterization of TLB and page allocation behavior on modern processors
No full textVirtual memory support is prevalent in most modern processors and is facilitated through Translation Lookaside Buffers (TLBs) which play a major role in the overall system performance. TLB misses are costly since they require multiple high latency memory references to walk the page table and locate the desired Virtual Page Number (VPN) - Physical Page Number (PPN) mapping. This study improves TLB hit rates by taking advantage of any contiguity present in the pages allocated by the Operating System (OS). By contiguity we refer to cases where consecutive VPNs are mapped to consecutive PPNs. Traditionally, OSs use large or superpages to collapse hundreds of such contiguous entries, thereby using one TLB entry to represent them rather than hundreds of entries they would normally require. Unfortunately due to implementation complexities superpaging has not been universally successful in reducing TLB pressure. We show, however, that even without explicit superpaging, various OS virtual memory allocation activities lead to intermediate levels of contiguity that may be exploited to coalesce TLB entries and significantly improve hit rates. We verify the presence of contiguity by running benchmarks on a real system and checking the page allocations of the OS. The OS page allocation schemes depend on memory pressure and memory defragmentation daemons. Further, we find an average contiguity of 30 pages over all the benchmarks and configurations with superpaging turned on and about 10 with superpaging turned off. To verify the performance of a Coalesced TLB we have implemented a fully associative TLB with variable size and Least Recently Used (LRU) replacement policy. Our results show an average hit rate improvement of 25% by adding an 8-16 entry fully associative Coalesced TLB. The Coalesced TLB further needs no complex hardware to implement, hence providing to a low cost means to reduce miss rates.M.S.Includes bibliographical referencesby Viswanathan Vaidyanatha
Sustainable product and market development for subsistence marketplaces: Creating educational initiatives in radically different contexts
No full textDeveloping products and business processes to serve subsistence marketplaces (or the roughly 4 billion poor around the world referred to as the bottom of the pyramid) is a significant challenge for businesses. Despite the importance of subsistence marketplaces, most product development educational curricula have been focused on relatively resource-rich and literate consumers and markets. We teach an innovative year-long product development course which includes an international immersion experience and which covers a broad spectrum of learning from understanding poverty, to consumer behavior, to product development and engineering design specifically for subsistence consumers. This unique course represents a pioneering effort to focus attention and create knowledge about product development, marketing, management, and engineering practices for subsistence marketplaces. Our two-semester course sequence for graduate-level students in a variety of business and engineering disciplines and industrial design combines in-class pedagogy with experiential learning and results in useful and marketable product concepts and prototypes. Working on projects with multinational companies or startups, students identify an opportunity of general need, conduct field market research to better understand subsistence consumer needs and contexts through an international immersion experience, develop a product concept, convert the concept to a workable prototype, and develop a manufacturing plan, marketing strategy, and overall business plan for the product. Overlaying the content found in a typical new product development lab course we develop a contextual understanding of subsistence marketplaces, setting the stage for new product development. A central aspect of the learning experience is travel to subsistence markets for actual immersion in the context and to conduct market research. Our course is at the confluence of two of the most important issues facing humanity, subsistence and sustainability. Lessons learned here can also be extended to other radically different contexts, such as future scenarios involving severe energy shortages or climate change consequences. Such educational initiatives provide challenging learning experiences in preparing students for the unique demands of the 21st century. © 2011 Product Development and Management Association.APPLE LE, 1988, J PROD INNOVAT MANAG, V5, P70, DOI 10.1111-1540-5885.510070; ASHBY M, 2003, MATER TODAY, V6, P24, DOI 10.1016-S1369-7021(03)01223-9; Cardozo RN, 2002, J PROD INNOVAT MANAG, V19, P4, DOI 10.1016-S0737-6782(01)00116-3; CHICK A, 1997, J SUSTAINABLE PRODUC, V1, P53; Donaldson KM, 2006, RES ENG DES, V17, P135, DOI 10.1007-s00163-006-0017-3; Ehrenreich B., 2002, NICKEL DIMED; Eppinger S.D., 2002, DESIGN MANAGEMENT J, V13, P58; GESCHKA H, 1986, J PROD INNOVAT MANAG, V3, P48, DOI 10.1016-0737-6782(86)90043-3; GREEN M, 2006, P ASME DES ENG TECHN; HAMMOND A. L., 2007, INNOVATIONS, V2, P147, DOI [10.1162-itgg.2007.2.1-2.147, DOI 10.1162-ITGG.2007.2.1-2.147]; HANNUKAINEN P, 2006, P ASME DES ENG TECHN; Hargadon A, 2000, HARVARD BUS REV, V78, P157; HAUSER JR, 1988, HARVARD BUS REV, V66, P63; HERSTATT C, 1992, J PROD INNOVAT MANAG, V9, P213, DOI 10.1016-0737-6782(92)90031-7; HORAN J, 2004, ONE PAGE BUSINESS PL; Murcott S., 2007, J INT DEV, V19, P123, DOI 10.1002-jid.1353; Prahalad CK, 2002, HARVARD BUS REV, V80, P48; PRAHALAD CK, 2005, FORT BOTT PYR ER POV; PUGH P, 1991, TOTAL DESIGN INTEGRA; Rodriguez J, 2006, INTERACT COMPUT, V18, P956, DOI 10.1016-j.intcom.2006.05.007; Sahlman WA, 1997, HARVARD BUS REV, V75, P98; Schumacher Ernest F., 1973, SMALL IS BEAUTIFUL E; *SME, 2003, PLAST INJ MOLD; *SME, 2004, FUND MAN PROC SAMPL; Sridharan S, 2008, J CONSUM MARK, V25, P455, DOI 10.1108-07363760810915671; Stone R. B., 2000, Design Studies, V21, DOI 10.1016-S0142-694X(99)00003-4; TAGUCHI J, 1990, HARVARD BUS REV, V68, P65; Tybout JR, 2000, J ECON LIT, V38, P11, DOI 10.1257-jel.38.1.11; Ulrich K., 2007, PRODUCT DESIGN DEV; Viswanathan M, 2005, J MARKETING, V69, P15, DOI 10.1509-jmkg.69.1.15.55507; Viswanathan M., 2009, IVEY BUSINESS J MAR; Viswanathan M, 2009, J MACROMARKETING, V29, P406, DOI 10.1177-0276146709345620; Viswanathan M, 2008, EDUC ASIA PAC REG-IS, V12, P1, DOI 10.1007-978-1-4020-5769-4; Viswanathan M., 2007, PRODUCT MARKET DEV S, P1; Viswanathan M., 2007, PRODUCT MARKET DEV S, P212
Outside the fold conversion, modernity, and belief
No full text"Outside the Fold is a radical reexamination of religious conversion. Gauri Viswanathan skillfully argues that conversion is an interpretive act that belongs in the realm of cultural criticism. To that end, this work examines key moments in colonial and postcolonial history to show how conversion questions the limitations of secular ideologies, particularly the discourse of rights central to both the British empire and the British nation-state. Implicit in such questioning is an attempt to construct an alternative epistemological and ethical foundation of national community. Viswanathan grounds her study in an examination of two stimultaneous and, she asserts, linked events: the legal emancipation of religious minorities in England and the acculturation of colonial subjects to British rule. The author views these two apparently disparate events as part of a common pattern of national consolidation that produced the English state. She seeks to explain why resistance, in both cases, frequently took the form of religious conversion, especially to "minority" or alternative religions. Confronting the general characterization of conversion as assimilative and annihilating of identity, Viswanathan demonstrates that a willful change of religion can be seen instead as an act of opposition. Outside the Fold concludes that, as a form of cultural crossing, conversion comes to represent a vital release into difference.""Through the figure of the convert, Viswanathan addresses the vexing question of the role of belief and minority discourse in modern society. She establishes new points of contact between the convert as religious dissenter and as colonial subject. This convergence provides a transcultural perspective not otherwise visible in literary and historical texts. It allows for radically new readings of significant figures as diverse as John Henry Newman, Pandita Ramabai, Annie Besant, and B. R. Ambedkar, as well as close studies of court cases, census reports, and popular English fiction. These varying texts illuminate the means by which discourses of religious identity are produced, contained, or opposed by the languages of law, reason, and classificatory knowledge. Outside the Fold is a challenging, provocative contribution to the multidisciplinary field of cultural studies. Book jacket."--BOOK JACKE
REANALYSIS OF THE EMISSION SPECTRUM OF IN FOREIGN GASES
No full textA. L. Guy, K.S. Viswanathan, A. Sur, and J. Tellinghuisen, Chem. Phys. Lett. 73, 582 (1980). H. Hemmati and G. J. Collins, Chem. Phys. Lett. 67, 5 (1979). P. Venkateswarlu, Phys. Rev. 81. 821 (1951). R. D. Verma, Proc. Ind. Acad. Sci. 48A, 197 (1958). K.S. Viswanathan, A. Sur, and J. Tellinghuisen, J. Mol. Spectrosc. (in press).Author Institution:The emission spectrum of in foreign gases is studied as a function of pressure, temperature, end isotopic species, using a tesla discharge as Evidence is found for at least 12 of the 18 ion-pair states arising from , of which (2g) appears to be the lowest. The pressure- and temperature-dependent spectra support the suggestion that both the 3400-A system and a broad band near 5000 A originate from this state. High-resolution spectra show discrete structure in electronic bands at 2380 A, 2770 A, and 2880 A, in addition to the well-known F-X (2700 A), D-A(3400 A), and E-B (4300 A) systems. The 2380 system originates from a state near and terminates on the X state near v = 50. The 2770 system, which was previously as terminating on the X or B state, is now found to involve the A() The 2880 system terminates on a weakly bound lower slate which probably dissociates to ground-stale atoms. Work is continuing on the other electronic bands of the emission spectrum, most of which appear to be diffuse
Adaptive transmit power control based on signal strength and frame loss measurements for WLANs:
No full textIn the past few years, we witnessed a rapid penetration of Wireless Local Area Networks (WLANs) into the home and enterprise. Emerging technology such as the IEEE 802.11n radio, which is getting increasingly affordable, makes delivering multimedia content over
wireless networks possible and this would drive the technology further into our daily life. As the number of available wireless channels in the unlicensed spectrum is limited (3 non-overlapping channels in 2.4GHz unlicensed band and up to 24 non-overlapping channels in 5GHz unlicensed band), they have to be shared by multiple WLANs consisting of Access Points (APs) and STAtions (STAs). In a Multi-Dwelling Unit (MDU) WLAN deployment, e.g. in an apartment building or hotel, transmissions in overlapping cells tend to interfere with each other. This will adversely impact the aggregate wireless network throughput and thus the quality of experience for applications such as multimedia streaming. Hence there is a need for automatic and adaptive resource management strategy to ensure a good overall network performance.
In this thesis we propose an adaptive per-link Transmit Power Control (TPC) solution for WLANs. TPC can reduce interference, increase channel reuse, and eventually increase the overall capacity in dense 802.11 wireless networks. However intelligent algorithms are
required to adapt transmit power in a practical and distributed way to achieve improvement in performance. It becomes more challenging given different types of interference (cooperative and non-cooperative) in the unlicensed band as well as the hidden node problem. From a detailed study of the previous efforts at power control, we observe that in order to make better decisions on transmit power; an AP needs to actively monitor several factors. Hence we develop a TPC algorithm based on both link margin estimation as well as frame loss rate measurement. Compared to previous solutions that adapt the transmit power based on measurement of a single parameter (either received signal strength or frame loss rate), the proposed power control mechanism can diagnose and take remedial action for hidden nodes and channel access asymmetry problems manifesting as frame losses. It is adaptive to mobility, complementary to any rate control algorithm and can also be incrementally deployed amidst non-cooperative nodes. We have implemented the algorithm as an application running on Atheros chipset-based 802.11n APs, taking practical system-level limitations into account. The proposed solution achieves significant transmit power reduction at the APs (to as low as 60% of the maximum power) for STAs as far as 70ft and over ∼60% increase in total network throughput through interference mitigation.M.S.Includes bibliographical references (p. 47-48)by Hariharasudhan Viswanatha
Publishing in wireless and wireline environments
No full textPublishing is a spontaneous and periodic broadcasting of information by a server. This dissertation shows how publishing can be efficiently used in both low bandwidth wireless networks and high bandwidth wireline networks. The first part of this dissertation deals with publishing in wireless networks. The solutions that we propose for wireless environments are motivated by the two most important resource constraints in such environments: limited power at the clients and scarce network bandwidth.
In a wireless environment it is crucial for the server to publish a directory along with the data. This enables battery powered clients to selectively download only relevant pieces of data, thereby saving significant power. However, publishing a directory leaves less bandwidth for the data itself. Thus, there is a need for efficient multiplexing of the directory along with the data in order to remove as little bandwidth as possible and simultaneously offer efficient solutions for power conservation at the clients. Such techniques are provided in this dissertation for both primary and secondary indexes. In addition, we also provide some hashing based solutions. This dissertation analytically demonstrates that the proposed techniques result in power and bandwidth conservation. Further on, we propose techniques for adaptive publishing when data items are accessed with different frequencies. Finally, we propose a general architecture for future wireless information systems. In wireline networks we focus on efficient utilization of network bandwidth. This dissertation proposes a new technique for providing key multimedia services like the Video On Demand service. It also provides analytical results demonstrating the benefits of this technique along with an implementation of its prototype on Ethernet LAN.Technical report lcsr-tr-24
Adaptive Wireless Information Systems
No full textWe provide an architecture for future wireless information services as a collection of autonomous cells which offer information services of widely varying geographic scope. Each MSS (Mobile Support Station) has the freedom to decide how to allocate different information services to its bandwidth and in which form to offer them. Two basic forms of delivery of information service are identified: periodic publishing mode on a publication subchannel and on-demand mode on the on-demand subchannel. We describe, how each MSS makes the decision about which form of service delivery to use and how to structure its publication subchannel by varying the frequency of publication of individual data items depending on the frequency of requests. In this way, we improve the packet efficiency and power efficiency of the client-server protocols by maximizing the number of queries per Hz and queries per Watt. Each mobile client has to be able to interoperate in this environment. This is assured by making cells self-explanatory about their service allocation. We describe how the presented concepts can be implemented by proposing an extension of WWW protocol, called adaptive WWW. We also show how to implement the proposed protocol along the lines of CDPD.Technical report DCS-TR-31
Pyramid broadcasting for video on demand service
No full textThe proposed scheme of pyramid broadcasting is a new way of rendering Video On Demand service at metropolitan scale. In pyramid broadcasting, the most frequently requested movies are multiplexed on the broadcast network, resulting in radical improvement of access time and efficient bandwidth utilization. We provide analytical and experimental evaluations of pyramid broadcasting based on its implementation on ethernet LAN, illustrating its advantages.Technical report DCS-TR-31
Rheumatic heart disease in Kerala – A vanishing entity? An echo Doppler study in 5–15 years old school children (2013–2014)
No full textCardiac troponin T estimation post elective stent implantation and prediction of early and late outcomes
No full textBackground: Coronary artery disease (CAD) is a major cause of mortality and morbidity. Per Cutaneous Interventions (PCI) is emerging as the mainstay of treatment for CAD. Periprocedural myocardial necrosis, which can range from a low-level elevation of cardiac biomarkers to a large myocardial infarction, is an important complication of PCI. There are conflicting reports regarding peri-procedural biomarker elevation and adverse outcome. It is in this context we have undertaken this study to assess the prognostic significance of cardiac troponin T elevation after elective stent implantation.Methods: The study population included 100 consecutive patients who underwent elective PCI with stent implantation in cardiology unit of Medical College, Trivandrum. Serial cardiac enzyme levels were measured in all patients undergoing the procedure. CPK was measured at 8 hrs, 16 hrs and 24 hrs and Troponin T was measured at 8hrs and 24 hrs. post PCI. In hospital events were documented and patients were on follow up for a period of 1 year. Primary endpoints of death, myocardial infarction, recurrent ischemia leading to revascularization were noted.Results: In our study population of 100 patients there were 87 males and 13 females. Among them 50% had unstable angina, 18% had exertional angina and 32% were post myocardial infarction patients. In this group of hundred patients 79% had single vessel disease, 18% had two vessels and 3% had triple vessel disease. A total of 103 stents were deployed. Mean CPK levels were CPK-1 (80.11+36.19), mean CPK-2 (83.91± 34.8) and mean CPK-3 (86.32+57.80). Mean Troponin T-1 was 0.04+0.1 and mean Troponin-2 was 0.06+0.145. In this study, we compared late onset angina with Troponin and CPK positivity and found that both Troponin-1 & Troponin-2 had significant correlation with late onset angina.Conclusions: Periprocedural Troponin T is more sensitive than CPK in predicting late events. Thrombus containing lesions and bifurcation lesions were significantly associated with elevation in Troponin T. No significant Troponin T elevations were noted in patients with diabetes mellitus and those containing calcified lesions. Drug eluting stents were associated with a relatively lesser Troponin T elevations but not statistically significant.</jats:p
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