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383 results on '"Dutta, P. S."'

1. ModZoo: A Large-Scale Study of Modded Android Apps and their Markets

Author

Saavedra, Luis A., Dutta, Hridoy S., Beresford, Alastair R., and Hutchings, Alice

Subjects
Computer Science - Other Computer Science, Computer Science - Cryptography and Security, Computer Science - Software Engineering
Abstract

We present the results of the first large-scale study into Android markets that offer modified or modded apps: apps whose features and functionality have been altered by a third-party. We analyse over 146k (thousand) apps obtained from 13 of the most popular modded app markets. Around 90% of apps we collect are altered in some way when compared to the official counterparts on Google Play. Modifications include games cheats, such as infinite coins or lives; mainstream apps with premium features provided for free; and apps with modified advertising identifiers or excluded ads. We find the original app developers lose significant potential revenue due to: the provision of paid for apps for free (around 5% of the apps across all markets); the free availability of premium features that require payment in the official app; and modified advertising identifiers. While some modded apps have all trackers and ads removed (3%), in general, the installation of these apps is significantly more risky for the user than the official version: modded apps are ten times more likely to be marked as malicious and often request additional permissions.

Published
2024

4. Rate-Induced Transitions in Networked Complex Adaptive Systems: Exploring Dynamics and Management Implications Across Ecological, Social, and Socioecological Systems

Author

Vasconcelos, Vítor V., Marquitti, Flávia M. D., Ong, Theresa, McManus, Lisa C., Aguiar, Marcus, Campos, Amanda B., Dutta, Partha S., Jovanelly, Kristen, Junquera, Victoria, Kong, Jude, Krueger, Elisabeth H., Levin, Simon A., Liao, Wenying, Lu, Mingzhen, Mittal, Dhruv, Pascual, Mercedes, Pinheiro, Flávio L., Rocha, Juan, Santos, Fernando P., Sloot, Peter, Chenyang, Su, Taylor, Benton, Tekwa, Eden, Terpstra, Sjoerd, Tilman, Andrew R., Watson, James R., Yang, Luojun, Yitbarek, Senay, and Zhan, Qi

Subjects
Physics - Physics and Society, Computer Science - Multiagent Systems, Mathematics - Dynamical Systems, Nonlinear Sciences - Adaptation and Self-Organizing Systems, 37G, 37N, 91B, 91C, 91D, 91E, 92D, 92D25, 92D40, 92F, 93A, 93A14, 93A16, I.6.3, I.6.m, J.3, J.4, J.m, K.4.2
Abstract

Complex adaptive systems (CASs), from ecosystems to economies, are open systems and inherently dependent on external conditions. While a system can transition from one state to another based on the magnitude of change in external conditions, the rate of change -- irrespective of magnitude -- may also lead to system state changes due to a phenomenon known as a rate-induced transition (RIT). This study presents a novel framework that captures RITs in CASs through a local model and a network extension where each node contributes to the structural adaptability of others. Our findings reveal how RITs occur at a critical environmental change rate, with lower-degree nodes tipping first due to fewer connections and reduced adaptive capacity. High-degree nodes tip later as their adaptability sources (lower-degree nodes) collapse. This pattern persists across various network structures. Our study calls for an extended perspective when managing CASs, emphasizing the need to focus not only on thresholds of external conditions but also the rate at which those conditions change, particularly in the context of the collapse of surrounding systems that contribute to the focal system's resilience. Our analytical method opens a path to designing management policies that mitigate RIT impacts and enhance resilience in ecological, social, and socioecological systems. These policies could include controlling environmental change rates, fostering system adaptability, implementing adaptive management strategies, and building capacity and knowledge exchange. Our study contributes to the understanding of RIT dynamics and informs effective management strategies for complex adaptive systems in the face of rapid environmental change., Comment: 25 pages, 4 figures, 1 box, supplementary information

Published
2023

5. A computational framework for weighted simplicial homology

Author

Bura, Andrei C., Dutta, Neelav S., Li, Thomas J. X., and Reidys, Christian M.

Subjects
Mathematics - Algebraic Topology, Computer Science - Symbolic Computation, Mathematics - Combinatorics, Mathematics - General Topology, Mathematics - K-Theory and Homology, 05E45, 55U10, 55N35, 13P20
Abstract

We provide a bottom up construction of torsion generators for weighted homology of a weighted complex over a discrete valuation ring $R=\mathbb{F}[[\pi]]$. This is achieved by starting from a basis for classical homology of the $n$-th skeleton for the underlying complex with coefficients in the residue field $\mathbb{F}$ and then lifting it to a basis for the weighted homology with coefficients in the ring $R$. Using the latter, a bijection is established between $n+1$ and $n$ dimensional simplices whose weight ratios provide the exponents of the $\pi$-monomials that generate each torsion summand in the structure theorem of the weighted homology modules over $R$. We present algorithms that subsume the torsion computation by reducing it to normalization over the residue field of $R$, and describe a Python package we implemented that takes advantage of this reduction and performs the computation efficiently., Comment: 16 pages, 2 figures

Published
2022

6. Illuminating the Role of Classmates in Reducing the Participation Gender Gap in Lecture-Based Engineering Classes

Author

Dutta, Nikita S. and Arnold, Craig B.

Abstract

Contribution: This work sheds light on how classmate behaviors influence gender gaps in verbal participation in lecture-based engineering classes. It is found that after a woman participates in class, there is a temporarily increased likelihood a woman will participate again afterward. Background: Women continue to be underrepresented in STEM higher education, particularly in engineering. Positive classroom experiences are key to retaining women undergraduates, but despite research into the value of interactive teaching that allows classmates to aid each other's learning, lecturing is still most common in collegiate STEM classrooms. Research Questions: This study considers how classmates influence gender gaps in student verbal participation, even during traditional lecturing. Methodology: One thousand and three hundred and eighty seven student comments are observed over 89 class periods in ten engineering courses. The variation in student verbal participation levels with gender is analyzed, and its correlation with student speaking order, as well as other factors related to the classroom structure, is investigated. Findings: A statistically significant gender gap in class participation is observed, which is not fully explained by factors like class size or comment type. It is found, however, that when one woman participates, it increases the likelihood a woman will participate afterward, pointing to the role of classmates. This trend and the participation gender gap overall are eliminated when isolating classes taught by women. These results suggest that hearing either a woman classmate or instructor speak in class makes other women more likely to do so. As participation is linked to everything from student performance to confidence, this provides an avenue to increase gender equity in classroom experiences through small pedagogical changes that can be readily implemented into traditional lecturing.

Published
2022
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10. Pattern of genetic diversity in indigenous Ahu rice germplasm of Assam

Author

M. K. Sarma*, A. S. Nizamuddin Ahmed, Daizi Durba Saharia , Manash P. Nath, Jugal talukdar, N. Sonia Devi, S. Dutta Deka, S. Zaman and J. Bhuyan

Subjects
genetic variation, genetic divergence, ahu rice, rainfed upland, Plant culture, SB1-1110
Abstract

The north-eastern part of India including Assam is one of the key centres of diversity of cultivated rice. Among the diverse varietal types, Ahu group of varieties with their evolutionary significance being intermediate between indica and japonica deserves attention for their detailed evaluation and utilisation in crop improvement programme. This work was attempted to elucidate the pattern of genetic variation and genetic diversity in a set of 147 indigenous Ahu rice genotypes of Assam grown under rainfed upland direct seeded condition. Among the 13 traits under study, the highest genotypic coefficient of variation was exhibited by primary branches per plant followed by secondary branches per plant and grain yield. Heritability in broad sense was the highest for grain L: B ratio followed by grain width and grain length. More than 90% heritability in broad sense was, observed for all the traits except effective tillers per plant, panicle length and grain yield. The highest genetic advance as per cent of mean was observed for primary branches per plant followed by secondary branches per plant and grain yield. Hence, selection for these traits would be most effective for further genetic improvement. At the intermediate linkage distance, four main and nine sub clusters were obtained by Euclidean cluster analysis. Cluster III b was the largest containing 35 entries, which was followed by cluster I c containing 32 entries. The variety Chidon Ahu remained distinct from all other entries and belonged to cluster I b. Based on per se performances of the genotypes and their inter se distance, promising genotypes were suggested for hybridization in order to obtain desirable segregants for further genetic improvement of Ahu rices.

Published
2022
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14. Some Interesting Properties of the Second Network of Hall

Author

Dutta Roy, S. C. and Nelatury, Sudarshan Rao

Abstract

This paper deals with the properties of the second Hall network in details, by a comprehensive analysis and simulation. Both normal form of the network and its reoriented version are considered – the first one being a band-stop and the latter a band-pass filter. Interestingly, the band-stop version gives an over unity gain.

Published
2024
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15. Cooperative Information Sharing to Improve Distributed Learning in Multi-Agent Systems

Author

Dutta, P. S., Jennings, N. R., and Moreau, L.

Subjects
Computer Science - Multiagent Systems
Abstract

Effective coordination of agents actions in partially-observable domains is a major challenge of multi-agent systems research. To address this, many researchers have developed techniques that allow the agents to make decisions based on estimates of the states and actions of other agents that are typically learnt using some form of machine learning algorithm. Nevertheless, many of these approaches fail to provide an actual means by which the necessary information is made available so that the estimates can be learnt. To this end, we argue that cooperative communication of state information between agents is one such mechanism. However, in a dynamically changing environment, the accuracy and timeliness of this communicated information determine the fidelity of the learned estimates and the usefulness of the actions taken based on these. Given this, we propose a novel information-sharing protocol, post-task-completion sharing, for the distribution of state information. We then show, through a formal analysis, the improvement in the quality of estimates produced using our strategy over the widely used protocol of sharing information between nearest neighbours. Moreover, communication heuristics designed around our information-sharing principle are subjected to empirical evaluation along with other benchmark strategies (including Littmans Q-routing and Stones TPOT-RL) in a simulated call-routing application. These studies, conducted across a range of environmental settings, show that, compared to the different benchmarks used, our strategy generates an improvement of up to 60% in the call connection rate; of more than 1000% in the ability to connect long-distance calls; and incurs as low as 0.25 of the message overhead.

Published
2011
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20. Study of Zn diffusion in n-type GaSb by cathodoluminescence and scanning tunneling spectroscopy

Author

Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P: S., Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, and Dutta, P: S.

Abstract

© 2001 Elsevier Science B.V. This work was supported by DGES (Project PB96- 0639)., We report here the studies carried out in zinc diffused n-type GaSb by cathodoluminescence (CL) microscopy and by scanning tunneling spectroscopy. Samples with different diffusion profiles measured by secondary ion mass spectrometry (SIMS) were obtained. CL plan-view observations show high homogeneity in the diffused layers. Cross-sectional measurements of the Zn diffused layers were performed by current imaging tunneling spectroscopy (CITS). The junction border was revealed clearly in the CITS images and conductance spectra recorded at differents points of the layers provided information on the local surface band gaps and the conductive behaviour. The results were related to the diffusion profiles and were found to agree with diffusion models suggested previously., DGES, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

21. Nature of compensating luminescence centers in Te-diffused and -doped GaSb

Author

Dutta, P. S., Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dieguez, E., Bhat, H. L., Dutta, P. S., Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dieguez, E., and Bhat, H. L.

Abstract

© 1996 American Institute of Physics. P.S.D. thanks CSIR (India) for the award of the Senior Research Fellowship. This work was partially supported by the Instituto Nicolas Cabrera, UAM, Madrid, Spain, through a visiting scientist fellowship and by the DGICYT (Project No. PB93-1256), CICYT (IN 93-0012), and ESP-95-0148., Diffusion of tellurium In undoped p-GaSb has been carried out. Using the cathodoluminescence and photoluminescence techniques, the luminescence centers in Te-diffused samples have been identified and compared with the Te-doped bulk GaSb. Fundamental differences in the radiative levels are observed between the diffused and the as-grown doped samples. Evidence for self-compensating acceptor complexes are seen in diffused samples. With short and moderate diffusion times, a compensating acceptor complex VGaGaSbTeSb is observed. For long diffusion times, the dominant acceptor center has been attributed to the antisite defect Ga-Sb or related complex. The reasons for the formation of various acceptor centers have been discussed., Instituto Nicolas Cabrera, DGICYT, CICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

22. Effect of In doping in GaSb crystals studied by cathodoluminescence

Author

Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P: S., Dieguez, E., Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P: S., and Dieguez, E.

Abstract

© 1999 IOP Publishing Ltd. This work has been supported by the DGES (project No PB96-0639) and CICYT (projects ESP95-0148 and ESP98-1340)., The luminescence properties of In doped GaSb single crystals have been studied by the cathodoluminescence (CL) technique in the scanning electron microscope. It has been found that indium induces a certain reduction on the native acceptor concentration in contrast to what occurs with other isoelectronic dopants (e.g. aluminium). Large In concentrations lead to the formation of the ternary compound In_xGa_(1-x)Sb as revealed by CL spectra and x-ray measurements. In particular, a luminescence band and x-ray diffraction peaks observed in highly doped samples are attributed to the presence of In_xGa_(1-x)Sb., DGES, CICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

23. Luminescence properties of transition-metal-doped GaSb

Author

Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Dutta, P: S., Piqueras de Noriega, Javier, Dieguez, E., Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Dutta, P: S., Piqueras de Noriega, Javier, and Dieguez, E.

Abstract

© The American Physical Society. This Work Was Supported By The DGICYT (Project No. PB93-1256) And CICYT (Project No. 95-0086-OP)., The luminescence properties of transition-metal (Cr, V, and Ru)-doped GaSb single crystals have been studied by a cathodoluminescence (CL) technique in a scanning electron microscope. Spatial segregation of impurities along the longitudinal direction of the crystals grown by the Bridgman method has been investigated. These dopants suppress the native acceptor concentration to varying extent. The behavior of Ru has been found to be different from the behavior of V and Cr. In particular the complete disappearance of the 777 meV (band A) emission has been observed in GaSb:Ru with a low doping level. A peak at 767 meV is also seen in this sample which, to the best of our knowledge, has not been previously observed in GaSb. The CL results have been complemented by x-ray-microanalysis measurements to ascertain the effect of doping level on the luminescence properties., DGICYT, CICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

24. Cathodoluminescence studies of growth and process-induced defects in bulk gallium antimonide

Author

Méndez Martín, Bianchi, Dutta, P. S., Piqueras de Noriega, Javier, Dieguez, E., Méndez Martín, Bianchi, Dutta, P. S., Piqueras de Noriega, Javier, and Dieguez, E.

Abstract

© 1991 All Rights Reserved. This work has been supported by the DGICYT (Project No. PB93-1256) and ESP95-0148. One of the authors (P.S.D.) gratefully thanks CSIR (India) for the award of the Senior Research Fellowship and UAM, Madrid, Spain, for the visiting scientist fellowship., The homogeneity and luminescence properties of undoped bulk GaSb have been studied by the cathodoluminescence (CL) technique in the scanning electron microscope. CL images have revealed a nonuniform distribution of native defects in GaSb wafers prepared from as-grown single crystals. Postgrowth annealing in vacuum, gallium, and antimony atmospheres has been performed to obtain more accurate information about the defect structure in this material. In general, on annealing, homogeneous distribution of impurities is observed throughout the wafers. CL spectra show that a luminescence band (centered at 756 meV) is enhanced by annealing in a gallium atmosphere, suggesting that Ga atoms play an important role in the formation of this acceptor center. The 756 meV peak has been attributed to a transition from conduction band to an acceptor center comprised of Ga-Sb or a related complex. Interestingly, localized crystallization at the subgrain boundaries seems to occur by annealing in Ga atmosphere., DGICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

25. Passivation of surface and bulk defects in p-GaSb by hydrogenated amorphous silicon treatment

Author

Dutta, P. S., Sreedhar, A. K., Bhat, H. L., Dubey, G. C., Kumar, V., Dieguez, E., Pal, U., Piqueras de Noriega, Javier, Dutta, P. S., Sreedhar, A. K., Bhat, H. L., Dubey, G. C., Kumar, V., Dieguez, E., Pal, U., and Piqueras de Noriega, Javier

Abstract

© 1996 American Institute of Physics One of the authors (P.S.D.) would like to thank CSIR (India) for the award of a senior research fellowship. U.P. gratefully acknowledges MEC (Spain) for the postdoctoral fellowship. This work was partially supported by the Universidad Autonoma de Madrid, Spain, through a visiting scientist fellowship and by DGICYT Project Nos. PB93-1256 and ESP95-014, Passivation of point and extended defects in GaSb has been observed as a result of hydrogenated amorphous silicon (a-Si:H) treatment by the glow discharge technique. Cathodoluminescence (CL) images recorded at various depths in the samples clearly show passivation of defects on the surface as well as in the bulk region. The passivation of various recombination centers in the bulk is attributed to the formation of hydrogen-impurity complexes by diffusion of hydrogen ions from the plasma a-Si:H acts as a protective cap layer and prevents surface degradation which is usually encountered by bare exposure to hydrogen plasma. An enhancement in luminescence intensity up to 20 times is seen due to the passivation of nonradiative recombination centers. The passivation efficiency is found to improve with an increase in a-Si:H deposition temperature. The relative passivation efficiency of donors and acceptors by hydrogen in undoped and Te-compensated p-GaSb has been evaluated by CL and by the temperature dependence of photoluminescence intensities. Most notably, effective passivation of minority dopants in tellurium compensated p-GaSb is evidenced for the first time., Universidad Autonoma de Madrid, Spain, DGICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

26. Scanning tunneling spectroscopy of transition-metal-doped GaSb

Author

Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P: S., Dieguez, E., Hidalgo Alcalde, Pedro, Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P: S., and Dieguez, E.

Abstract

©1999 The American Physical Society. This work was supported by DGES (PB96-0639) and by CICYT (ESP98-1340) (MAT98-1306E)., V- and Ru-doped GaSb crystals have been investigated by scanning tunneling spectroscopy in a combined scanning electron microscope-scanning tunneling microscope system. Local variations of surface band gap have been measured with high spatial resolution. Precipitates in both kinds of doped samples show a nearly metallic behavior. The surface band gaps in the GaSb matrix have been found to depend on the dopant. [S0163-1829(99)06439-5]., DGES, CICYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

27. P-to n-type Conversion in GaSb by ion-beam milling

Author

Panin, G. N., Dutta, P. S., Piqueras de Noriega, Javier, Dieguez, E., Panin, G. N., Dutta, P. S., Piqueras de Noriega, Javier, and Dieguez, E.

Abstract

(C) 1995 American Institute of Physics. G. Panin thanks Ministerio de Educacion y Ciencia for a research grant and P. S. Dutta thanks CSIR (India) for the award of Senior Research Fellowship. This work was partially supported by the Instituto Nicolas Cabrera, UAM, Madrid, Spain, through a Visiting Scientist Fellowship and by the DGICYT (Project PB93-1256), CICYT (IN93-00129 and ESP95-0148., Inversion in conductivity type of GaSb from p- to n- has been observed as a result of argon ion beam milling. Electron beam induced current (EBIC) measurements have been employed for detecting the type conversion. Enhancement in the luminescence intensity is seen after ion beam treatment. The type conversion is proposed to occur due to a combined effect of generation of native donors and gettering of native accepters originally present in the as-grown samples., DGICYT, CICYT, Ministerio de Educación y Ciencia, Instituto Nicolas Cabrera, UAM, Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

28. Cathodoluminescence microscopy of doped GaSb crystals

Author

Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P. S., Dieguez, E., Méndez Martín, Bianchi, Piqueras de Noriega, Javier, Dutta, P. S., and Dieguez, E.

Abstract

© 1996 - Elsevier Science S.A. International Workshop on Beam Injection Assessment of Defects in Semiconductors (BIADS 96) (4.1996. El Escorial, Madrid)., We present the homogeneity and luminescence properties of bulk GaSb obtained by the cathodoluminescence (CL) technique in the scanning electron microscope. The samples used in this study are as-grown undoped and impurity diffused (tellurium) and doped (chromium) material. CL investigations have revealed a non uniform distribution of native defects in GaSb wafers. Post growth annealing in vacuum, gallium or antimony atmospheres causes an increase in homogeneity in CL images. Te diffusion and Cr doping provides new information about defects in GaSb. CL images and CL spectra recorded in these samples support that the type of defects formed is a function of diffusion time and impurity concentration., Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

29. Filtering With Uniformly Distributed RC Networks

Author

Dutta Roy, S. C. and Nelatury, Sudarshan Rao

Abstract

This brief presents filters made with two uniformly distributed RC network elements – either by cascading or paralleling or differencing. Filters of all types, except all-pass are considered. Expressions for the voltage gain in each case are provided, which happen to be irrational functions of the normalized frequency variable. Predicting the nature of the overall frequency response for each of these connections from the physical reasoning proves to be nontrivial. By explicitly deriving the transfer functions and actually computing we are able to identify filter characteristics.

Published
2024
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42. JUST-R metrics for considering energy justice in early-stage energy research

Author

Dutta, Nikita S., Gill, Elizabeth, Arkhurst, Bettina K., Hallisey, Mary, Fu, Katherine, and Anderson, Kate

Abstract

Nikita S. Dutta is a director’s postdoctoral fellow in the Materials Science Center of the National Renewable Energy Laboratory (NREL). She received her PhD in materials science from Princeton University and BS in physics from Yale University. Her research focuses on developing and applying novel electron microscopy methods to study structural evolution and degradation of materials in energy technologies.

Published
2023
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