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Search Results: 1 - 10 of 7889 matches for " Anupam Das "
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On the relative proof complexity of deep inference via atomic flows
Anupam Das
Computer Science , 2015,
Abstract: We consider the proof complexity of the minimal complete fragment, KS, of standard deep inference systems for propositional logic. To examine the size of proofs we employ atomic flows, diagrams that trace structural changes through a proof but ignore logical information. As results we obtain a polynomial simulation of versions of Resolution, along with some extensions. We also show that these systems, as well as bounded-depth Frege systems, cannot polynomially simulate KS, by giving polynomial-size proofs of certain variants of the propositional pigeonhole principle in KS.
Is Grant-Aid More Effective than Concessional Loans? Evidence from a Dynamic Panel of Sub-Saharan African Countries
Anupam Das,Syeed Khan
International Journal of Economics and Finance , 2011, DOI: 10.5539/ijef.v4n1p14
Abstract: Despite being one of the highest aid recipient regions, the growth performance in Sub-Saharan Africa (SSA) has been rather disappointing. In this paper, we answer two questions. 1) Is there any significant impact of foreign aid on economic growth? 2) Is grant more effective than loans in promoting growth? To answer these questions, we employ a GMM technique for a panel of 27 SSA countries over the period of 1961 to 2009. By using this technique, we are able to control for endogeneity that may arise from explanatory variables. Our results suggest that grant aid is more effective than concessional loans. On average, aggregate aid’s effect on economic growth is not discernable from zero in SSA countries. These questions are important for policymakers of SSA who often face the dilemma of high aid but low growth.
Aid-Growth Nexus in South Asia: Evidence from Time Series and Panel Cointegration
Murshed Chowdhury,Anupam Das
Research in Applied Economics , 2011, DOI: 10.5296/rae.v3i1.601
Abstract: Given the strong likelihood of a sharp decline in remittance flows because of the recent recession, coupled with limited access to the global capital market, foreign aid inflow in South Asia can play an important role in boosting economic growth in this region. In the existing literature, the relationship between foreign aid and per capita real GDP is rather inconclusive. Does aid work in South Asia? We answer this question for five economies in this region: Bangladesh, India, Nepal, Pakistan, and Sri Lanka. Using both country-specific time series and a recently developed panel cointegration procedure over the period 1976 to 2008, our results suggest a positive long run relationship between growth rate of per capita real GDP and aid as a percentage of GDP for four out of five countries. Hence, this investigation tends to support the aid effectiveness hypothesis for South Asian countries.
Securing Tor Tunnels under the Selective-DoS Attack
Anupam Das,Nikita Borisov
Computer Science , 2011,
Abstract: Anonymous communication systems are subject to selective denial-of-service (DoS) attacks. Selective DoS attacks lower anonymity as they force paths to be rebuilt multiple times to ensure delivery which increases the opportunity for more attack. In this paper we present a detection algorithm that filters out compromised communication channels for one of the most widely used anonymity networks, Tor. Our detection algorithm uses two levels of probing to filter out potentially compromised tunnels. We perform probabilistic analysis and extensive simulation to show the robustness of our detection algorithm. We also analyze the overhead of our detection algorithm and show that we can achieve satisfactory security guarantee for reasonable communication overhead (5% of the total available Tor bandwidth in the worst case). Real world experiments reveal that our detection algorithm provides good defense against selective DoS attack.
Spindle Cell Carcinoma of the Head and Neck: A Clinicopathological and Immunohistochemical Study of 40 Cases  [PDF]
Anupam Sarma, Rajjyoti Das, J. D. Sharma, A. C. Kataki
Journal of Cancer Therapy (JCT) , 2012, DOI: 10.4236/jct.2012.36137
Abstract: Spindle cell carcinoma of head and neck, a subtype of squamous cell carcinoma is a unique and rare neoplasm. It has a more aggressive behavior as compared to classical squomous cell carcinoma warranting surgical interventions with wider surgical margins. Immunohistochemistry along with routine histopathology is essential in establishing the diagnosis of spindle cell carcinoma. We at Dr. B. Borooah Cancer Institute, Guwahati, a regional institute for treatment and research, hereby report 40 cases of such lesion with clinicopathological and immunohistochemical study. Out of total 40 cases included in the study group most of the cases were in the age group of 40 to 60 years. Commonest site of presentation was nasopharynx and buccal mucosa. 14 cases of the oral cavity (buccal mucosa, alveolus, oral tongue and hard palate) were treated with surgery. All the cases with disease of the larynx and hypopharynx were treated with radiotherapy and cases involving the nasopharynx received radiotherapy and chemotherapy. In the surgery group recurrence rate was found to be 71.4% and metastasis rate was 21.4%. Biopsy specimens were subjected to histopathological examination followed by immunohistochemistry. Immunohistochemical analysis show concurrent presence of malignant epithelial and sarcomatoid spindle cell components by co-expression of cytokeratin (CK) and vimentin to various degrees.
The Remittance-GDP Relationship in the Liberalized Regime of Bangladesh: Cointegration and Innovation Accounting
Biru Paksha PAUL,Anupam DAS
Theoretical and Applied Economics , 2011,
Abstract: Bangladesh, being one of the top remittance-recipient countries in the world, has drawn attention to the remittance-output relationship in recent years. The results on this aspect are nevertheless inconclusive. Working on a relatively liberalized regime from 1979 to 2009, this study finds a long run positive relationship between remittances and GDP in Bangladesh. The adjustment of this relation, however, goes against traditional belief in that GDP does not respond to the movements in remittances while correcting disequilibrium after a shock in the system, but the reverse is true. There is no evidence on remittance-led growth in the short run. Innovation accounting shows that the impact of output on remittances is remarkably stronger than that of remittances on output. These findings have policy implications for other emerging nations in that GDP growth is capable of attracting further remittances arguably through increasing investment demand and initiating institutional reforms in the economy.
Glutathione transferase-P1-1 binding with naturally occurring ligands: assessment by docking simulations  [PDF]
Anupam J. Das, Sreeda Chalil, Poonam Nigam, Pamela Magee, Omar Janneh, Richard Owusu-Apenten
Journal of Biophysical Chemistry (JBPC) , 2011, DOI: 10.4236/jbpc.2011.24046
Abstract: Glutathione transferase-P1-1 (hGSTP1-1), which is associated with acquired drug resistance in some tumour cells, requires two identical subunits for full activity. Naturally occurring inhibitors for GSTP1-1 quaternary structure could be interesting therapeutic agents. The aim of this study was to investigate potential binding sites for hGSTP1-1 interaction with ligands many of which occur naturally. Simulations were performed with commercial docking software and with GST monomer or dimer as template. Docking results using hGSTP1-1 dimer showed one binding site for most of the ligands tested. Lycopene, glutathione, ellagic acid, ethacrynic acid, quercetin, caffeic acid, ferulic acid, porphyrin, curcumin, cinnamic acid, and also α-tocopherol bound at the enzyme dimer subunit-subunit interface. In contrast, investigations using hGSTP1-1 monomer revealed three additional sites for ligand binding. In conclusion, the docking simulations suggest that the enzyme subunit interface may be important for hGSTP1-1 interactions with ligands. These findings may provide valuable insights for further research to identify naturally occurring therapeutic agents.
Anupam Das,Meaghan Marie Beatty Parry
International Journal of Economics and Research , 2011,
Abstract: This paper employs the generalized method of moments (GMM) technique to a large sample of 74 developing countries over the period 2000 to 2008 to investigate the effect of corruption on the rate of investment. Overall results (all countries together) indicate that the control of corruption has a positive impact on the investment rate. Regional detailed investigations suggest that the effect of corruption control on the investment rate is positive in Sub-Saharan Africa, and Latin America and the Caribbean. No significant effect is found in Asia. In general, the sanding hypothesis is found to be dominant in our investigation
Fingerprinting Smart Devices Through Embedded Acoustic Components
Anupam Das,Nikita Borisov,Matthew Caesar
Computer Science , 2014,
Abstract: The widespread use of smart devices gives rise to both security and privacy concerns. Fingerprinting smart devices can assist in authenticating physical devices, but it can also jeopardize privacy by allowing remote identification without user awareness. We propose a novel fingerprinting approach that uses the microphones and speakers of smart phones to uniquely identify an individual device. During fabrication, subtle imperfections arise in device microphones and speakers which induce anomalies in produced and received sounds. We exploit this observation to fingerprint smart devices through playback and recording of audio samples. We use audio-metric tools to analyze and explore different acoustic features and analyze their ability to successfully fingerprint smart devices. Our experiments show that it is even possible to fingerprint devices that have the same vendor and model; we were able to accurately distinguish over 93% of all recorded audio clips from 15 different units of the same model. Our study identifies the prominent acoustic features capable of fingerprinting devices with high success rate and examines the effect of background noise and other variables on fingerprinting accuracy.
Exploring Ways To Mitigate Sensor-Based Smartphone Fingerprinting
Anupam Das,Nikita Borisov,Matthew Caesar
Computer Science , 2015,
Abstract: Modern smartphones contain motion sensors, such as accelerometers and gyroscopes. These sensors have many useful applications; however, they can also be used to uniquely identify a phone by measuring anomalies in the signals, which are a result from manufacturing imperfections. Such measurements can be conducted surreptitiously in the browser and can be used to track users across applications, websites, and visits. We analyze techniques to mitigate such device fingerprinting either by calibrating the sensors to eliminate the signal anomalies, or by adding noise that obfuscates the anomalies. To do this, we first develop a highly accurate fingerprinting mechanism that combines multiple motion sensors and makes use of (inaudible) audio stimulation to improve detection. We then collect measurements from a large collection of smartphones and evaluate the impact of calibration and obfuscation techniques on the classifier accuracy.
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