Krishnamurthy Vemuru - Profile on Academia.edu (original) (raw)

Papers by Krishnamurthy Vemuru

In FY 2016, the research team evaluated Security Cards, STRIDE (Spoofing identity, Tampering with... more In FY 2016, the research team evaluated Security Cards, STRIDE (Spoofing identity, Tampering with data, Repudiation, Information disclosure, Denial of service, Elevation of privilege), and persona non grata (PnG) for effectiveness in threat identification. Security Cards is an approach that emphasizes creativity and brainstorming over more structured approaches such as checklists. STRIDE involves modeling a system and subsystem and related data flows. PnGs represent archetypal users who behave in unwanted, possibly nefarious ways. The team used two scenarios: an aircraft maintenance scenario and a drone swarm scenario, both described in this technical note in detail, along with the project outcomes. No individual threat modeling method included all identified threats. The research team subsequently developed the Hybrid Threat Modeling Method (hTMM), considering the desirable characteristics for a Threat Modeling Method. At a high level, the hTMM includes the following steps, describ...

Low-exposure image frame generation algorithms for feature extraction and classification

Neuromorphic architectures enable machine learning on a faster timescale compared to conventional... more Neuromorphic architectures enable machine learning on a faster timescale compared to conventional processors and require encoding of spike trains from images for computer vision applications. We report low-exposure image representation algorithms that can generate multiple short-exposure frames from a given long exposure image. The frame deconvolution is non-linear in the sense that the difference between adjacent short-exposure frames change with exposure time, however the frames have a structural representation of the original image such that the image reconstructed from these frames has a Peak Signal-to-Noise Ratio (PSNR) of over 300 and a Structural Similarity Index Metric (SSIM) close to unity. We show that the low-exposure frames generated by our algorithms enable feature extraction for machine learning or deep learning, e. g., classification using convolutional neural networks. The validation accuracy for classification depends on the range of the random subtraction parameter...

Bulletin of the American Physical Society, 2016

Security Engineering FY17 Systems Aware Cybersecurity

Stephen Adams, University of Virginia Bryan Carter, University of Virginia Krishnamurthy Vemuru, ... more Stephen Adams, University of Virginia Bryan Carter, University of Virginia Krishnamurthy Vemuru, University of Virginia Carl Elks, Virginia Commonwealth University Tim Bakker, Virginia Commonwealth University Kryzsztof Cios, Virginia Commonwealth University Georgios Bakirtzis, Virginia Commonwealth University Aidan Collins, Virginia Commonwealth University Nancy Mead, Carnegie Mellon University Forrest Shull, Carnegie Mellon University

International Conference on Neuromorphic Systems 2021, 2021

Анотація. У статті подана загальна характеристика наукових поглядів на емоційне переживання. Дане... more Анотація. У статті подана загальна характеристика наукових поглядів на емоційне переживання. Дане поняття розкрито з точки зору філософії та психології. У філософії під переживанням науковці розуміють набуття особистістю досвіду; воно ототожнюється із свідомістю та є завжди цілісним і в своїй основі має тривалі ціннісні утворення. У психології переживання пов'язують у вузькому значенні із афективною сферою особистості, а у широкому -з пережитою особистістю подією, зміст якої мав значення і цінність для неї. Традиційно у психологічній науці категорію переживання розглядають із чотирьох позицій: гедоністичної, що пов'язує переживання із психічними станами; діяльністної, що переживанням вважає внутрішню діяльність особистості по сприйманню фактів і подій життя та по встановленню смислової відповідності між свідомістю та буттям; адаптаційної -переживання є здатністю особистості адаптуючись, мобілізувати всі ресурси психіки, щоб витримати напругу; екзистенціальна позиція розглядає переживання як спосіб буття особистості в світі, оскільки воно є перетином зовнішнього та внутрішнього світів. Переживання має змістовну складову, яка охоплює когнітивний, афективний та аксіологічний компонент; процесуальну складову, що включає в себе стратегічний і саморегуляційний компонент; особистісну складову, що містить індивідуально-психологічні властивості та модальність життєвої позиції. Окрім того, переживання є станом, що виникає при взаєминах зі світом, який залежить від особистої позиції і проявляється у поведінці; переживання є ставленням особистості до свого середовища, яка впливає на її самоставлення та проявляється у емоційно-чуттєвому та вегетативно-соматичному стані та у Журнал «Перспективи та інновації науки» (Серія «Педагогіка», Серія «Психологія», Серія «Медицина» № 3(3) 2021 292 відповідній цьому поведінці та діяльності; переживання є діяльністю по встановленню зв'язку зі світом, яка є похідною від самоставлення і здійснюється на основі наявного емоційного та соматичного стану. Ключові слова: переживання, самоставлення, саморегуляція, емоційночуттєвий стан, соматичний стан.

Algorithms, 2020

We report the design of a Spiking Neural Network (SNN) edge detector with biologically inspired n... more We report the design of a Spiking Neural Network (SNN) edge detector with biologically inspired neurons that has a conceptual similarity with both Hodgkin-Huxley (HH) model neurons and Leaky Integrate-and-Fire (LIF) neurons. The computation of the membrane potential, which is used to determine the occurrence or absence of spike events, at each time step, is carried out by using the analytical solution to a simplified version of the HH neuron model. We find that the SNN based edge detector detects more edge pixels in images than those obtained by a Sobel edge detector. We designed a pipeline for image classification with a low-exposure frame simulation layer, SNN edge detection layers as pre-processing layers and a Convolutional Neural Network (CNN) as a classification module. We tested this pipeline for the task of classification with the Digits dataset, which is available in MATLAB. We find that the SNN based edge detection layer increases the image classification accuracy at lower...

Physical Review B, 1997

The electric quadrupole interaction of 111 Cd in poly-and single-crystalline CuGeO 3 has been mea... more The electric quadrupole interaction of 111 Cd in poly-and single-crystalline CuGeO 3 has been measured in the temperature range from 4.2 to 556 K, using perturbed angular correlation spectroscopy. Two electric field gradients have been observed: a well-defined one having a quadrupole interaction frequency of q ϭ407 MHz and an asymmetry parameter of ϭ0.34 at room temperature, and a broadly distributed one. Possible sites for the implanted 111 In probes are discussed on the basis of the point charge model and perturbed angular correlation ͑PAC͒ results in CuO and other binary and ternary oxides. No anomalous change of the hyperfine interaction parameters has been detected at the spin-Peierls transition temperature T SP. We suggest that the absence of an anomaly at T SP is caused by the doping of CuGeO 3 with the 111 Cd PAC impurity, which prevents lattice distortions and spin dimerization at the nearest-neighbor Cu sites in Cu-O-Cu chains.

Physical Review B, 2003

Muon spin rotation/relaxation (ϩ SR) has been measured in the quasi-one-dimensional zigzag spin c... more Muon spin rotation/relaxation (ϩ SR) has been measured in the quasi-one-dimensional zigzag spin chain compounds ␣-CuNb 2 O 6 and ␤-CuNb 2 O 6. Spontaneous precession frequencies f 1 and f 2 observed at two muon sites in zero-field ϩ SR demonstrate antiferromagnetic ordering in ␤-CuNb 2 O 6 with a Néel temperature of 7.22 K. The frequencies give a measure of the temperature dependence of the intrachain field (ϰ f 2) and the interchain field (ϰ f 1). The temperature dependence of f 1 suggests a ferromagnetic intrachain coupling J in the ␤ phase. The interchain coupling JЈ that is responsible for the three-dimensional ordering is found to be 3.1 K. Using the values of J and JЈ, we estimate the magnetic moment of Cu to be 0.31 B. Muon longitudinal spin relaxation rate LF exhibits stretched exponential behavior in ␣-CuNb 2 O 6 in the temperature range of 150 to 2 K. LF increases sharply below 8 K, and the relaxation function becomes nearly root exponential at 4 K. These features show that the spin dynamics is very similar to that observed in a dilute spin-glass near its spin freezing temperature. The glasslike dynamics, which coexists with the spin-singlet state in the ␣ phase, has been attributed to a small fraction of Cu ions, which become bond impurities of spin-1/2, due to defects in the spin chains.

Physical Review Letters, 2002

Animal testing means the use of non-human animals in experiments. About 50 to 100 million vertebr... more Animal testing means the use of non-human animals in experiments. About 50 to 100 million vertebrates including rodents and non rodents are used for the purpose of such experiments in education and research. The non judicious use of these animals has affected the eco system and therefore many countries and scientists are looking for the alternatives for animal testing. The two major alternatives to in vivo animal testing are in vitro cell culture technique and in silico computer simulation. Still the alternative to animal testing needs to be developed. The present study was undertaken to justify the use of small intestine of chicken for isolated tissue experimentation which is a waste organ easily available from slaughter houses. The previous studies on chicken small intestine revealed the presence of tachykinin, histaminic, and motilin receptors. In the present study ileum portion of small intestine was used in tissue preparation. The contractile responses of variable doses of Acetylcholine solution were recorded on kymograph paper. The experiments were repeated to check the reproducibility, sensitivity and accuracy. The various parameters as tissue length, load/tension, magnification value, and physiological salt solution were studied to optimize the tissue experimentation conditions. The study showed that the chicken ileum may be one of the best, cheapest and easily available non mammalian tissues for experimentation on isolated organs and amongst various solutions Ringer Lock is the most suitable physiological solution.

Magnetism of Ir in Fe$_2$I"Rev. Sci. Instrum." from Ir L_2,3L_2,3L_2,3 edge x-ray magnetic circular dichroism spectroscopy

Magnetic and quadrupolar ordering phenomena in a Ce 3 Pd 20 Ge 6 single crystal have been investi... more Magnetic and quadrupolar ordering phenomena in a Ce 3 Pd 20 Ge 6 single crystal have been investigated by muon spin rotation/relaxation (µ + SR) spectroscopy. We have observed spontaneous precession of muons in zero-field below T N = 0.7 K in the antiferromagnetic state. The precession frequency follows the power law: ) is close to the mean-field value of 0.5. The muon longitudinal spin relaxation rate 1/T 1 is found to be nearly independent of temperature in the range of 0.3 to 2 K, i.e., across either T N or T Q = 1.2 K, the quadrupolar ordering temperature. Two likely mechanisms for the temperature independent behavior of 1/T 1 are suggested.

This technical report describes SSSim, the Simple and Scalable Simulator for P2P streaming system... more This technical report describes SSSim, the Simple and Scalable Simulator for P2P streaming systems. SSSim can be used to evaluate the streaming performance of different chunk and peer scheduling algorithms, and is designed for performance and scalability allowing the simulation of the diffusion of a very large number of chunks over large number of peers in reasonable times. This result has been obtained by optimising the simulator for recurrent workloads and minimising the memory footprint.

μ+SR study of heavy-fermion magnetism in Ce(Cu1-xNix)2Ge2

ABSTRACT We report muon spin relaxation (μ+SR) studies on the magnetic phase diagram of Ce(Cu1-xN... more ABSTRACT We report muon spin relaxation (μ+SR) studies on the magnetic phase diagram of Ce(Cu1-xNix)2Ge2 polycrystals for 0.5≤ x ≤ 0.8. A sharp magnetic transition, evidenced by the appearance of a fast Gaussian relaxation component σ, has been observed in the x = 0.5 alloy at 4.0 K in zero applied field. The average local field < Bμ> at the stopping sites of the muons, extracted from σ, exhibits a linear temperature dependence. We associate these features with an incommensurate spin density wave (SDW) ordering. Magnetic ordering, either long range or short range, and signatures of non-Fermi liquid behaviour have not been observed down to 2.0 K at x = 0.8.

Europium L2,3 and iron Kedge x-ray magnetic circular dichroism investigation of ferromagnetic ordering in EuFe4Sb12

The magnetic behavior of Eu and Fe in the filled skutterudite ferromagnet EuFe4Sb12 has been inve... more The magnetic behavior of Eu and Fe in the filled skutterudite ferromagnet EuFe4Sb12 has been investigated using Eu L2,3 edge and Fe K edge x-ray magnetic circular dichroism (XMCD) spectroscopy. Eu L3 edge x-ray absorption spectra (XAS) in EuFe4Sb12 clearly show that Eu is in a mixed valence state with about 15% non-magnetic Eu^3+ states at 5 K. By comparing

Physical Review E, 2003

Small-angle neutron scattering experiments have been performed to investigate orientational order... more Small-angle neutron scattering experiments have been performed to investigate orientational ordering of a dispersion of rod-shaped ferromagnetic nanoparticles under the influence of shear flow and static magnetic field. In this experiment, the flow and flow gradient directions are perpendicular to the direction of the applied magnetic field. The scattering intensity is isotropic in zero-shear-rate or zero-applied-field conditions, indicating that the particles are randomly oriented. Anisotropic scattering is observed both in a shear flow and in a static magnetic field, showing that both flow and field induce orientational order in the dispersion. The anisotropy increases with the increase of field and with the increase of shear rate. Three states of order have been observed with the application of both shear flow and magnetic field. At low shear rates, the particles are aligned in the field direction. When increasing shear rate is applied, the particles revert to random orientations at a characteristic shear rate that depends on the strength of the applied magnetic field. Above the characteristic shear rate, the particles align along the flow direction. The experimental results agree qualitatively with the predictions of a mean field model.

Magnetic order in the polar intermetallic CaMn2Sb2 studied via powder neutron diffraction

Journal of Magnetism and Magnetic Materials, 2009

This paper reports a neutron powder diffraction study of CaMn2Sb2 in the temperature range of 20-... more This paper reports a neutron powder diffraction study of CaMn2Sb2 in the temperature range of 20-300 K. Short-range magnetic order, characterized by a broad diffraction peak corresponding to a d spacing of 4 , is observed between 120 and 200 K. Collinear long-range antiferromagnetic order of manganese ions occurs below 85 K, where a transition is observed in the DC

We have observed x-ray magnetic circular dichroism ͑XMCD͒ in the helicity modulation mode at Ir L... more We have observed x-ray magnetic circular dichroism ͑XMCD͒ in the helicity modulation mode at Ir L 2,3 edges in the ferromagnet IrMnAl ͑Curie temperature 379 K͒ at room temperature, 100 K and 30 K. This observation proves that Ir has a 5d magnetic moment in IrMnAl. Using the magneto-optic sum rules, which relate the integrated intensity of the XMCD and x-ray absorption spectra to the expectation values of spin and orbital angular momenta of Ir, the orbital moment to spin moment ratio, the spin moment and the orbital moment of Ir at 30 K have been deduced to be Ϫ0.17(2), 0.018͑1͒ B , and Ϫ0.0031(8) B , respectively. dc magnetization measurements yielded a total moment of 0.123 B /atom showing that the magnetic moment of Mn is also strongly reduced. We suggest that the extremely small moments of Mn and Ir in IrMnAl are associated with the suppression of local moments and delocalization of 3d and 5d electrons due to their strong hybridization with the sp electrons of Al atoms.

Origin of Robust Ferromagnetism in Eu0.95Fe4Sb12

Physical Review Letters - PHYS REV LETT, 2007

We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5... more We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5} edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu{sub 0.95}FeSb is a ferrimagnet in which the Fe 3d moment and the Eu{sup 2+} 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L edge XAS, we find that about 13% of the Eu have a formal valence of 3{sup +}. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T{sub c} of 85 K in Eu{sub 0.95}FeSb to f-electron interaction with the nearly ferromagnetic [FeSb]{sup 2.2-} host lattice.

Pramana, 2002

The formation of induced 5d magnetic moment on Ir in Fe 100−x Ir x (x =3, 10 and 17) and Co 100−x... more The formation of induced 5d magnetic moment on Ir in Fe 100−x Ir x (x =3, 10 and 17) and Co 100−x Ir x (x = 5, 17, 25 and 32) alloys has been investigated by X-ray magnetic circular dichroism (XMCD) at Ir L 2,3 absorption edges. Sum rule analysis of the XMCD data show that the orbital moment of Ir is in the range of −0.071(2)µ B to −0.030(1)µ B in Fe-Ir alloys and −0.067(2)µ B to 0.024(1) µ B in Co-Ir alloys. We find that the total moment of Ir in Fe-Ir alloys is approximately 1/5 of the total 3d moment on Fe at all the three compositions. In contrast, the total moment on Ir in Co-Ir alloys varies between 1/6 to 1/16 of the 3d moment on cobalt. The observed trends of Ir moments and the role of interatomic exchange interactions in 5d moment formation are discussed.

In FY 2016, the research team evaluated Security Cards, STRIDE (Spoofing identity, Tampering with... more In FY 2016, the research team evaluated Security Cards, STRIDE (Spoofing identity, Tampering with data, Repudiation, Information disclosure, Denial of service, Elevation of privilege), and persona non grata (PnG) for effectiveness in threat identification. Security Cards is an approach that emphasizes creativity and brainstorming over more structured approaches such as checklists. STRIDE involves modeling a system and subsystem and related data flows. PnGs represent archetypal users who behave in unwanted, possibly nefarious ways. The team used two scenarios: an aircraft maintenance scenario and a drone swarm scenario, both described in this technical note in detail, along with the project outcomes. No individual threat modeling method included all identified threats. The research team subsequently developed the Hybrid Threat Modeling Method (hTMM), considering the desirable characteristics for a Threat Modeling Method. At a high level, the hTMM includes the following steps, describ...

Low-exposure image frame generation algorithms for feature extraction and classification

Neuromorphic architectures enable machine learning on a faster timescale compared to conventional... more Neuromorphic architectures enable machine learning on a faster timescale compared to conventional processors and require encoding of spike trains from images for computer vision applications. We report low-exposure image representation algorithms that can generate multiple short-exposure frames from a given long exposure image. The frame deconvolution is non-linear in the sense that the difference between adjacent short-exposure frames change with exposure time, however the frames have a structural representation of the original image such that the image reconstructed from these frames has a Peak Signal-to-Noise Ratio (PSNR) of over 300 and a Structural Similarity Index Metric (SSIM) close to unity. We show that the low-exposure frames generated by our algorithms enable feature extraction for machine learning or deep learning, e. g., classification using convolutional neural networks. The validation accuracy for classification depends on the range of the random subtraction parameter...

Bulletin of the American Physical Society, 2016

Security Engineering FY17 Systems Aware Cybersecurity

Stephen Adams, University of Virginia Bryan Carter, University of Virginia Krishnamurthy Vemuru, ... more Stephen Adams, University of Virginia Bryan Carter, University of Virginia Krishnamurthy Vemuru, University of Virginia Carl Elks, Virginia Commonwealth University Tim Bakker, Virginia Commonwealth University Kryzsztof Cios, Virginia Commonwealth University Georgios Bakirtzis, Virginia Commonwealth University Aidan Collins, Virginia Commonwealth University Nancy Mead, Carnegie Mellon University Forrest Shull, Carnegie Mellon University

International Conference on Neuromorphic Systems 2021, 2021

Анотація. У статті подана загальна характеристика наукових поглядів на емоційне переживання. Дане... more Анотація. У статті подана загальна характеристика наукових поглядів на емоційне переживання. Дане поняття розкрито з точки зору філософії та психології. У філософії під переживанням науковці розуміють набуття особистістю досвіду; воно ототожнюється із свідомістю та є завжди цілісним і в своїй основі має тривалі ціннісні утворення. У психології переживання пов'язують у вузькому значенні із афективною сферою особистості, а у широкому -з пережитою особистістю подією, зміст якої мав значення і цінність для неї. Традиційно у психологічній науці категорію переживання розглядають із чотирьох позицій: гедоністичної, що пов'язує переживання із психічними станами; діяльністної, що переживанням вважає внутрішню діяльність особистості по сприйманню фактів і подій життя та по встановленню смислової відповідності між свідомістю та буттям; адаптаційної -переживання є здатністю особистості адаптуючись, мобілізувати всі ресурси психіки, щоб витримати напругу; екзистенціальна позиція розглядає переживання як спосіб буття особистості в світі, оскільки воно є перетином зовнішнього та внутрішнього світів. Переживання має змістовну складову, яка охоплює когнітивний, афективний та аксіологічний компонент; процесуальну складову, що включає в себе стратегічний і саморегуляційний компонент; особистісну складову, що містить індивідуально-психологічні властивості та модальність життєвої позиції. Окрім того, переживання є станом, що виникає при взаєминах зі світом, який залежить від особистої позиції і проявляється у поведінці; переживання є ставленням особистості до свого середовища, яка впливає на її самоставлення та проявляється у емоційно-чуттєвому та вегетативно-соматичному стані та у Журнал «Перспективи та інновації науки» (Серія «Педагогіка», Серія «Психологія», Серія «Медицина» № 3(3) 2021 292 відповідній цьому поведінці та діяльності; переживання є діяльністю по встановленню зв'язку зі світом, яка є похідною від самоставлення і здійснюється на основі наявного емоційного та соматичного стану. Ключові слова: переживання, самоставлення, саморегуляція, емоційночуттєвий стан, соматичний стан.

Algorithms, 2020

We report the design of a Spiking Neural Network (SNN) edge detector with biologically inspired n... more We report the design of a Spiking Neural Network (SNN) edge detector with biologically inspired neurons that has a conceptual similarity with both Hodgkin-Huxley (HH) model neurons and Leaky Integrate-and-Fire (LIF) neurons. The computation of the membrane potential, which is used to determine the occurrence or absence of spike events, at each time step, is carried out by using the analytical solution to a simplified version of the HH neuron model. We find that the SNN based edge detector detects more edge pixels in images than those obtained by a Sobel edge detector. We designed a pipeline for image classification with a low-exposure frame simulation layer, SNN edge detection layers as pre-processing layers and a Convolutional Neural Network (CNN) as a classification module. We tested this pipeline for the task of classification with the Digits dataset, which is available in MATLAB. We find that the SNN based edge detection layer increases the image classification accuracy at lower...

Physical Review B, 1997

The electric quadrupole interaction of 111 Cd in poly-and single-crystalline CuGeO 3 has been mea... more The electric quadrupole interaction of 111 Cd in poly-and single-crystalline CuGeO 3 has been measured in the temperature range from 4.2 to 556 K, using perturbed angular correlation spectroscopy. Two electric field gradients have been observed: a well-defined one having a quadrupole interaction frequency of q ϭ407 MHz and an asymmetry parameter of ϭ0.34 at room temperature, and a broadly distributed one. Possible sites for the implanted 111 In probes are discussed on the basis of the point charge model and perturbed angular correlation ͑PAC͒ results in CuO and other binary and ternary oxides. No anomalous change of the hyperfine interaction parameters has been detected at the spin-Peierls transition temperature T SP. We suggest that the absence of an anomaly at T SP is caused by the doping of CuGeO 3 with the 111 Cd PAC impurity, which prevents lattice distortions and spin dimerization at the nearest-neighbor Cu sites in Cu-O-Cu chains.

Physical Review B, 2003

Muon spin rotation/relaxation (ϩ SR) has been measured in the quasi-one-dimensional zigzag spin c... more Muon spin rotation/relaxation (ϩ SR) has been measured in the quasi-one-dimensional zigzag spin chain compounds ␣-CuNb 2 O 6 and ␤-CuNb 2 O 6. Spontaneous precession frequencies f 1 and f 2 observed at two muon sites in zero-field ϩ SR demonstrate antiferromagnetic ordering in ␤-CuNb 2 O 6 with a Néel temperature of 7.22 K. The frequencies give a measure of the temperature dependence of the intrachain field (ϰ f 2) and the interchain field (ϰ f 1). The temperature dependence of f 1 suggests a ferromagnetic intrachain coupling J in the ␤ phase. The interchain coupling JЈ that is responsible for the three-dimensional ordering is found to be 3.1 K. Using the values of J and JЈ, we estimate the magnetic moment of Cu to be 0.31 B. Muon longitudinal spin relaxation rate LF exhibits stretched exponential behavior in ␣-CuNb 2 O 6 in the temperature range of 150 to 2 K. LF increases sharply below 8 K, and the relaxation function becomes nearly root exponential at 4 K. These features show that the spin dynamics is very similar to that observed in a dilute spin-glass near its spin freezing temperature. The glasslike dynamics, which coexists with the spin-singlet state in the ␣ phase, has been attributed to a small fraction of Cu ions, which become bond impurities of spin-1/2, due to defects in the spin chains.

Physical Review Letters, 2002

Animal testing means the use of non-human animals in experiments. About 50 to 100 million vertebr... more Animal testing means the use of non-human animals in experiments. About 50 to 100 million vertebrates including rodents and non rodents are used for the purpose of such experiments in education and research. The non judicious use of these animals has affected the eco system and therefore many countries and scientists are looking for the alternatives for animal testing. The two major alternatives to in vivo animal testing are in vitro cell culture technique and in silico computer simulation. Still the alternative to animal testing needs to be developed. The present study was undertaken to justify the use of small intestine of chicken for isolated tissue experimentation which is a waste organ easily available from slaughter houses. The previous studies on chicken small intestine revealed the presence of tachykinin, histaminic, and motilin receptors. In the present study ileum portion of small intestine was used in tissue preparation. The contractile responses of variable doses of Acetylcholine solution were recorded on kymograph paper. The experiments were repeated to check the reproducibility, sensitivity and accuracy. The various parameters as tissue length, load/tension, magnification value, and physiological salt solution were studied to optimize the tissue experimentation conditions. The study showed that the chicken ileum may be one of the best, cheapest and easily available non mammalian tissues for experimentation on isolated organs and amongst various solutions Ringer Lock is the most suitable physiological solution.

Magnetism of Ir in Fe$_2$I"Rev. Sci. Instrum." from Ir L_2,3L_2,3L_2,3 edge x-ray magnetic circular dichroism spectroscopy

Magnetic and quadrupolar ordering phenomena in a Ce 3 Pd 20 Ge 6 single crystal have been investi... more Magnetic and quadrupolar ordering phenomena in a Ce 3 Pd 20 Ge 6 single crystal have been investigated by muon spin rotation/relaxation (µ + SR) spectroscopy. We have observed spontaneous precession of muons in zero-field below T N = 0.7 K in the antiferromagnetic state. The precession frequency follows the power law: ) is close to the mean-field value of 0.5. The muon longitudinal spin relaxation rate 1/T 1 is found to be nearly independent of temperature in the range of 0.3 to 2 K, i.e., across either T N or T Q = 1.2 K, the quadrupolar ordering temperature. Two likely mechanisms for the temperature independent behavior of 1/T 1 are suggested.

This technical report describes SSSim, the Simple and Scalable Simulator for P2P streaming system... more This technical report describes SSSim, the Simple and Scalable Simulator for P2P streaming systems. SSSim can be used to evaluate the streaming performance of different chunk and peer scheduling algorithms, and is designed for performance and scalability allowing the simulation of the diffusion of a very large number of chunks over large number of peers in reasonable times. This result has been obtained by optimising the simulator for recurrent workloads and minimising the memory footprint.

μ+SR study of heavy-fermion magnetism in Ce(Cu1-xNix)2Ge2

ABSTRACT We report muon spin relaxation (μ+SR) studies on the magnetic phase diagram of Ce(Cu1-xN... more ABSTRACT We report muon spin relaxation (μ+SR) studies on the magnetic phase diagram of Ce(Cu1-xNix)2Ge2 polycrystals for 0.5≤ x ≤ 0.8. A sharp magnetic transition, evidenced by the appearance of a fast Gaussian relaxation component σ, has been observed in the x = 0.5 alloy at 4.0 K in zero applied field. The average local field < Bμ> at the stopping sites of the muons, extracted from σ, exhibits a linear temperature dependence. We associate these features with an incommensurate spin density wave (SDW) ordering. Magnetic ordering, either long range or short range, and signatures of non-Fermi liquid behaviour have not been observed down to 2.0 K at x = 0.8.

Europium L2,3 and iron Kedge x-ray magnetic circular dichroism investigation of ferromagnetic ordering in EuFe4Sb12

The magnetic behavior of Eu and Fe in the filled skutterudite ferromagnet EuFe4Sb12 has been inve... more The magnetic behavior of Eu and Fe in the filled skutterudite ferromagnet EuFe4Sb12 has been investigated using Eu L2,3 edge and Fe K edge x-ray magnetic circular dichroism (XMCD) spectroscopy. Eu L3 edge x-ray absorption spectra (XAS) in EuFe4Sb12 clearly show that Eu is in a mixed valence state with about 15% non-magnetic Eu^3+ states at 5 K. By comparing

Physical Review E, 2003

Small-angle neutron scattering experiments have been performed to investigate orientational order... more Small-angle neutron scattering experiments have been performed to investigate orientational ordering of a dispersion of rod-shaped ferromagnetic nanoparticles under the influence of shear flow and static magnetic field. In this experiment, the flow and flow gradient directions are perpendicular to the direction of the applied magnetic field. The scattering intensity is isotropic in zero-shear-rate or zero-applied-field conditions, indicating that the particles are randomly oriented. Anisotropic scattering is observed both in a shear flow and in a static magnetic field, showing that both flow and field induce orientational order in the dispersion. The anisotropy increases with the increase of field and with the increase of shear rate. Three states of order have been observed with the application of both shear flow and magnetic field. At low shear rates, the particles are aligned in the field direction. When increasing shear rate is applied, the particles revert to random orientations at a characteristic shear rate that depends on the strength of the applied magnetic field. Above the characteristic shear rate, the particles align along the flow direction. The experimental results agree qualitatively with the predictions of a mean field model.

Magnetic order in the polar intermetallic CaMn2Sb2 studied via powder neutron diffraction

Journal of Magnetism and Magnetic Materials, 2009

This paper reports a neutron powder diffraction study of CaMn2Sb2 in the temperature range of 20-... more This paper reports a neutron powder diffraction study of CaMn2Sb2 in the temperature range of 20-300 K. Short-range magnetic order, characterized by a broad diffraction peak corresponding to a d spacing of 4 , is observed between 120 and 200 K. Collinear long-range antiferromagnetic order of manganese ions occurs below 85 K, where a transition is observed in the DC

We have observed x-ray magnetic circular dichroism ͑XMCD͒ in the helicity modulation mode at Ir L... more We have observed x-ray magnetic circular dichroism ͑XMCD͒ in the helicity modulation mode at Ir L 2,3 edges in the ferromagnet IrMnAl ͑Curie temperature 379 K͒ at room temperature, 100 K and 30 K. This observation proves that Ir has a 5d magnetic moment in IrMnAl. Using the magneto-optic sum rules, which relate the integrated intensity of the XMCD and x-ray absorption spectra to the expectation values of spin and orbital angular momenta of Ir, the orbital moment to spin moment ratio, the spin moment and the orbital moment of Ir at 30 K have been deduced to be Ϫ0.17(2), 0.018͑1͒ B , and Ϫ0.0031(8) B , respectively. dc magnetization measurements yielded a total moment of 0.123 B /atom showing that the magnetic moment of Mn is also strongly reduced. We suggest that the extremely small moments of Mn and Ir in IrMnAl are associated with the suppression of local moments and delocalization of 3d and 5d electrons due to their strong hybridization with the sp electrons of Al atoms.

Origin of Robust Ferromagnetism in Eu0.95Fe4Sb12

Physical Review Letters - PHYS REV LETT, 2007

We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5... more We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5} edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu{sub 0.95}FeSb is a ferrimagnet in which the Fe 3d moment and the Eu{sup 2+} 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L edge XAS, we find that about 13% of the Eu have a formal valence of 3{sup +}. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T{sub c} of 85 K in Eu{sub 0.95}FeSb to f-electron interaction with the nearly ferromagnetic [FeSb]{sup 2.2-} host lattice.

Pramana, 2002

The formation of induced 5d magnetic moment on Ir in Fe 100−x Ir x (x =3, 10 and 17) and Co 100−x... more The formation of induced 5d magnetic moment on Ir in Fe 100−x Ir x (x =3, 10 and 17) and Co 100−x Ir x (x = 5, 17, 25 and 32) alloys has been investigated by X-ray magnetic circular dichroism (XMCD) at Ir L 2,3 absorption edges. Sum rule analysis of the XMCD data show that the orbital moment of Ir is in the range of −0.071(2)µ B to −0.030(1)µ B in Fe-Ir alloys and −0.067(2)µ B to 0.024(1) µ B in Co-Ir alloys. We find that the total moment of Ir in Fe-Ir alloys is approximately 1/5 of the total 3d moment on Fe at all the three compositions. In contrast, the total moment on Ir in Co-Ir alloys varies between 1/6 to 1/16 of the 3d moment on cobalt. The observed trends of Ir moments and the role of interatomic exchange interactions in 5d moment formation are discussed.