Possible potentials responsible for stable circular relativistic orbits

Bertrand's theorem in classical mechanics of the central force fields attracts us because of its predictive power. It categorically proves that there can only be two types of forces which can produce stable, circular orbits. In the present article an attempt has been made to generalize Bertrand's theorem to the central force problem of relativistic systems. The stability criterion for potentials which can produce stable, circular orbits in the relativistic central force problem has been deduced and a general solution of it is presented in the article. It is seen that the inverse square law passes the relativistic test but the kind of force required for simple harmonic motion does not. Special relativistic effects do not allow stable, circular orbits in presence of a force which is proportional to the negative of the displacement of the particle from the potential center.Comment: 11 pages, Latex fil

Anomalous Raman scattering from phonons and electrons of superconducting FeSe0.82_{0.82}

We report interesting anomalies in the temperature dependent Raman spectra of FeSe$_{0.82}$ measured from 3K to 300K in the spectral range from 60 to 1800 cm$^{-1}$ and determine their origin using complementary first-principles density functional calculations. A phonon mode near 100 cm$^{-1}$ exhibits a sharp increase by $\sim$ 5% in frequency below a temperature T$_s$ ($\sim$ 100 K) attributed to strong spin-phonon coupling and onset of short-range antiferromagnetic order. In addition, two high frequency modes are observed at 1350 cm$^{-1}$ and 1600 cm$^{-1}$, attributed to electronic Raman scattering from ($x^2-y^2$)to $xz$ / $yz$ $d$-orbitals of Fe.Comment: 19 pages, 4 figures, 1 tabl

BEP Performance Analysis of Multi-Node Self Encoded Spread Spectrum - Cooperative Diversity in Rayleigh Fading Channel

Self - encoded spread spectrum (SESS) is a novel modulation technique th at acquires its spreading sequence from the random input data stream rather than through the use of the traditional pseudo - noise code generator. It has been incorporated with multi node cooperative diversity systems as a means to combat fading in wireless channels. In this paper we analyze the cooperative SESS for Amplify and Forward CD links ( M SESS - AFCD) and SESS for Decode and forward CD links ( M SESS - DFCD) in Rayleigh fading channels. The BE P expressions are derived in closed form, and the veracity of the analysis is confirmed by numerical calculations that demonstrate excellent agreement with simulation results

ASSESSMENT OF LOW BONE MASS USING PERIPHERAL DUAL X-RAY ABSORPTIOMETRY (PDXA) IN DIFFERENT ETHNIC GROUPS

  Objectives: The main aim of this study was to assess the low bone mass in younger adults using peripheral dual X-ray absorptiometry (pDXA) and also to find the co-relational aspect of Indian, Nepal-Bhutan, and Afghanistan men.Methods: In this study, 70 younger adults aged from 18 to 25 years were incorporated. In every adult, bone mineral density (BMD) of the left forearm (LF-BMD), right forearm (RF-BMD), left calcaneum (LC-BMD), and right calcaneum (RC-BMD) were measured by pDXA. The back-propagation neural network classifier is used in the classification of low bone mass and healthy controls, and the statistical tool was used to find the co-relational aspect of various BMD measurements.Results: The LC-BMD positively correlated (p<0.05) with subject's body weight and body mass index (BMI) r=0.40 in Indian men. The LC-BMD and RC-BMD were positively correlated (p<0.05 and p<0.01) with BMI (r=0.549 and r=0.63) in Nepal-Bhutan men. In Afghanistan men, LF-BMD and RF-BMD are positively correlated (p<0.05 and p<0.01) with BMI (r=0.49 and r=0.80). The accuracy of the classifier was found to be 94.3% and 97.1% with RF-BMD and RC-BMD in the total population.Conclusion: The result suggested that the forearm and calcaneum BMD measured by pDXA shows statistically high significant correlation with BMI, which can be used for screening purpose, and also it will be helpful in the evaluation of low bone mass in the developing countries

Consumer online purchase behaviour: perception versus expectation

Conceptualising online customer behaviour is very important, as more and more customers are interested in buying products through online. To capture online customer behaviour, this study has conducted empirical research in Bangladesh among general online customers who have experience in online buying or have an intention to buy from online boutique websites in Bangladesh. In this regard, the quality-purchase interaction model that was developed, based on both customer perception and the expectation of buying online from business-to-consumer electronic-commerce in Bangladesh, was used to capture actual customer behaviour or behavioural intention for online purchasing. We conducted path analysis through LISREL to reveal the causal relation between independent and dependent variables. There are some significant differences between online buying behaviour and the behavioural intention to buy online, that is between customers who have experience of online buying from a boutique website and those who have the intention to buy online but have not yet gotten an online buying experience

Service delivery through mobile-government (mGov): Driving factors and cultural impacts

The mobile-Government (mGov) service system is conducted through an open network, and it is virtual. This service mode and pattern change inevitably necessitates a behavioral change in citizen attitudes and intentions. Nevertheless, this new pattern of service delivery through mGov has hardly been systematically investigated by any researchers. The objective of this current research is twofold. First, we attempt to reveal the sources of beliefs for developing intention toward the mGov (ITM) system. Then, as the second objective, we investigate cultural influence as the reason for a difference in consumer attitudes and intentions toward mGov. In this regard, the empirical study was conducted in Bangladesh and the USA, which have potential differences in the cultural traits listed by Hofstede. From our statistical analysis, we have identified the sources of beliefs for both Bangladeshi and USA consumers.We observed clear differences in sources of beliefs and their influence on attitudes leading to intention, which demonstrates support for our second objective which was designed to verify the cultural impacts on belief-attitude relations.We understand that these different sources of beliefs influence cognitive, affective, and connative attitudes toward mGov in different ways

LaF3 core/shell nanoparticles for subcutaneous heating and thermal sensing in the second biological-window

We report on Ytterbium and Neodymium codoped LaF3 core/shell nanoparticles capable of simultaneous heating and thermal sensing under single beam infrared laser excitation. Efficient light-to-heat conversion is produced at the Neodymium highly doped shell due to non-radiative de-excitations. Thermal sensing is provided by the temperature dependent Nd3+ → Yb3+ energy transfer processes taking place at the core/shell interface. The potential application of these core/shell multifunctional nanoparticles for controlled photothermal subcutaneous treatments is also demonstratedThis work was supported by the Spanish Ministerio de Economıa y Competitividad (MAT2013-47395-C4-1-R), by Brazilian Agencies: FINEP (Financiadora de Estudos e Projetos) through the Grant Nos. INFRAPESQ-11 and INFRAPESQ-12; CNPq (Conselho Nacional de Desenvolvimento Cientıfico e Tecnologico) Grants INCT NANO(BIO)SIMES and Project Universal No. 483238/2013-9; CAPES (Coordenadoria de Aperfeiçoamento de Pessoal de Ensino Superior) by means of the Project PVE No. A077/2013. Erving C. Ximendes is supported by a Ph.D. scholarship from CNPq and currently by the PVE A077/2013 Project by means of a Ph.D. sandwich program developed at the Universidad Autonoma de Madrid, Spain. Prof. Dr. Daniel Jaque is the PVE (Pesquisador Visitante Especial) of the Project No. A077/2013. Dr. K. U. Kumar is a post-doctoral fellow of this Project. Dr. Ueslen Rocha is supported by a Post Doctoral Fellowship grant PDE/CAPES at the Universidad Autonoma de Madrid-Spain through the Project No. 2108-14-

Raman Evidence for Superconducting Gap and Spin-Phonon Coupling in Superconductor Ca(Fe0.95Co0.05)2As2

Inelastic light scattering studies on single crystal of electron-doped Ca(Fe0.95Co0.05)2As2 superconductor, covering the tetragonal to orthorhombic structural transition as well as magnetic transition at TSM ~ 140 K and superconducting transition temperature Tc ~ 23 K, reveal evidence for superconductivity-induced phonon renormalization; in particular the phonon mode near 260 cm-1 shows hardening below Tc, signaling its coupling with the superconducting gap. All the three Raman active phonon modes show anomalous temperature dependence between room temperature and Tc i.e phonon frequency decreases with lowering temperature. Further, frequency of one of the modes shows a sudden change in temperature dependence at TSM. Using first-principles density functional theory-based calculations, we show that the low temperature phase (Tc < T < TSM) exhibits short-ranged stripe anti-ferromagnetic ordering, and estimate the spin-phonon couplings that are responsible for these phonon anomalies

Antimicrobial effects of Indian medicinal plants against acne-inducing bacteria

Propionibacterium acnes and Staphylococcus epidermidis have been recognized as pus-forming bacteria triggering an inflammation in acne. The present study was conducted to evaluate antimicrobial activities of Indian medicinal plants against these etiologic agents of acne vulgaris. Ethanolic extracts of Hemidesmus indicus (roots), Eclipta alba (fruits), Coscinium fenestratum (stems), Curcubito pepo (seeds), Tephrosia purpurea (roots), Mentha piperita (leaves), Pongamia pinnata (seeds), Symplocos racemosa (barks), Euphorbia hirta (roots), Tinospora cordyfolia (roots), Thespesia populnea (roots), and Jasminum officinale (flowers) were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion method showed that 07 medicinal plants could inhibit the growth of Propionibacterium acnes. Among those Hemidesmus indicus, Coscinium fenestratum, Tephrosia purpurea, Euphorbia hirta, Symplocos racemosa, Curcubito pepo and Eclipta alba had strong inhibitory effects. Based on a broth dilution method, the Coscinium fenestratum extract had the greatest antimicrobial effect. The MIC values were the same (0.049 mg/ml) for both bacterial species and the MBC values were 0.049 and 0.165 mg/ml against Propionibacterium acnes and Staphylococcus epidermidis, respectively. In bioautography assay, the Coscinium fenestratum extract produced strong inhibition zones against Propionibacterium acnes. Phytochemical screening of Coscinium fenestratum revealed the presence of alkaloid which could be responsible for activity. Taken together, our data indicated that Coscinium fenestratum had a strong inhibitory effect on Propionibacterium acnes and Staphylococcus epidermidis. . Keywords: Acne; Propionibacterium acnes; Staphylococcus epidermidis; Antimicrobial activity > Tropical Journal of Pharmaceutical Research Vol. 6 (2) 2007: pp. 717-72