Dynamics of Crossover from a Chaotic to a Power Law State in Jerky Flow

We study the dynamics of an intriguing crossover from a chaotic to a power law state as a function of strain rate within the context of a recently introduced model which reproduces the crossover. While the chaotic regime has a small set of positive Lyapunov exponents, interestingly, the scaling regime has a power law distribution of null exponents which also exhibits a power law. The slow manifold analysis of the model shows that while a large proportion of dislocations are pinned in the chaotic regime, most of them are pushed to the threshold of unpinning in the scaling regime, thus providing insight into the mechanism of crossover.Comment: 5 pages, 3 figures. In print in Phy. Rev. E Rapid Communication

A study on hypersurface of complex space form

We show that quasi-umbilical, generalized quasi-umbilical, super quasi-umbilical hypersurfaces of a complex space form are quasi-Einstein, mixed generalized quasi-Einstein and mixed super quasi-Einstein manifolds, respectively. We also prove that a Bochner at space of generalized complex space form is an Einstein manifold

STUDY OF PREVALENCE AND ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF BACTERIAL ISOLATES IN A TERTIARY CARE HOSPITAL

Objective: Many human illnesses are bacterial in origin which can be treated with appropriate antibiotics and selection of these is mostly based on culture and sensitivity. The problem of antimicrobial resistance has burgeoned throughout the world both in inpatients and outpatients. We must work together to preserve the power of antimicrobials so as to use these effectively in treating diseases. The aim of the study is to find out the prevalence of infection and sensitivity pattern among bacterial pathogens in a tertiary care hospital.Methods: This retrospective study was carried out in Vinayaka Missions Medical College and Hospital, Karaikal, Puducherry (U. T) to study the culture and sensitivity pattern of clinical isolates from blood, urine, sputum, wound, ear/throat swab for one year (June 2012- June 2013). The positive cultures and their antibiotic susceptibility testing were performed under the guidelines of Clinical and Laboratory Standard Institute (CLSI). The lab data from Microbiology department were utilized and filled in a proforma and analyzed.Results: Out of 788 samples, 296 were culture positive. Isolated bacteria were mostly Gram negative organisms (GNO) of which Klebsiella (41.55%) was commonly followed by Pseudomonas (15.20%), Escherichia coli(4.05%) and Proteus (3.71%). Among Gram positive organisms (GPO) Staphylococcus (35.47%) was common. Imipenem (100%), Gentamycin (90.20%), Amikacin (89.14%), were the antimicrobials most sensitive for GNO, while Ceftriaxone (100%), Cefotaxime(100%),Nitrofurantoin(96.15%) and Linezolid(92.13%) were most sensitive for GPO. Widespread resistance to Nalidixic acid (99%),Ampicillin (85.90%), Cefuroxime (75%) is seen in both groups, while Cefazolin(79.25%) and Norfloxacin(83%) was noted for GNO, resistance to Amoxicillin with clavulanic acid (81.66%) and Imipenem(55.55%) was noted for GPO.Conclusion: The technical abilities to detect novel, resistant mechanisms and to overcome the microbial resistance has to be improved. Antibiotic policies agreed among clinicians, microbiologists and pharmacologists will guide good prescribing, provide maximum coverage for treating infections and ensure antibiotic cycling.Â

Chaos and Dynamical localization in interacting kicked systems

Is quantum localization preserved under the effect of interactions that make a system non-integrable and completely chaotic? This work attempts to answer this question through a detailed study of the momentum-coupled, two-body linear kicked rotor model. It was recently shown that dynamical many-body localization exists in an integrable model of spatially interacting linear kicked rotors. Later, such localized phases in a non-integrable model -- coupled relativistic kicked rotors -- were also shown to exist. However, the presence of dynamical localization remains an open question in an interacting system that is far from the integrable limit and hence is completely chaotic. In this work, we show that chaos can be induced in the integrable linear kicked rotor model through interactions between the momenta of rotors. An approximate estimate of its Lyapunov exponent is obtained. Further, the quantum dynamics of this chaotic model, upon variation of kicking and interaction strengths, is shown to exhibit a variety of phases -- classically induced localization, dynamical localization, subdiffusive and diffusive phases. We also discuss this perspective from entanglement production in this system. By defining an effective Hilbert space dimension, the entanglement growth rate can be understood using appropriate random matrix averages.Comment: 11 pages, 6 figure

The nutrition transition in India

No Abstract.South African Journal of Clinical Nutrition Vol. 18(2) 2005: 198-20

Neonatal septic arthritis: Clinical profile and predictors of outcome

Background: Neonatal septic arthritis deserves a special attention due to its subtle signs and symptoms and catastrophicconsequences. There is paucity of literature regarding the clinical profile and predictors of outcome in neonatal septic arthritis.Objectives: The objective was to study the clinical profile of neonates admitted with septic arthritis, their clinical and radiologicaloutcomes on follow-up, and factors that predict outcomes. Methodology: Neonates with septic arthritis as assessed by retrospectivecase sheet review were included. Prospective data collection of clinical and radiological outcomes was done during follow-upvisits. Children with good outcomes (controls) were compared to those with poor outcomes (cases) subsequently to identifythe predictors of outcomes using a nested case–control design. Results: Data of 70 neonates admitted with septic arthritis werecollected. Single joint involvement was common (75.8%), and hip joint was the most common joint involved. Gram-negativeorganisms were predominant (72%), and Klebsiella was the most common organism isolated from joint aspirate (36%), followed byEscherichia coli and Staphylococcus aureus. Of 52 babies who turned for follow-up, half had poor outcomes. In univariate analysis,multiple joint involvement (odds ratio [OR] 4.79, [confidence interval (CI): 1.14-20.21]), pre-intervention period ≥7 days (OR 92,[CI: 14.06-601.9]), culture positive joint aspirate (OR 3.70, [CI: 1.55-11.86]), and restricted range of joint movements at discharge(OR 83.3, [CI: 9.2-749.9]) were significantly associated with poor outcomes. Pre-intervention period ≥7 days (adjusted OR 107.99,[CI: 5.16-2258.8]) and restricted joint mobility at discharge (adjusted OR 139.53, [CI: 9.03-2154.04]) were the independentpredictors of poor overall outcome by logistic regression analysis. Conclusions: Long pre-intervention period and restricted jointmobility at discharge were independent predictors of poor outcome in neonatal septic arthritis. We emphasize the importance ofearly diagnosis, prompt referral to tertiary centers, timely surgical intervention, appropriate measures to ensure good joint mobility,and regular follow-up in these neonates to achieve best outcomes

Life cycle and morphometry of Rugose spiraling whitefly, Aleyrodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) on coconut

The present study investigated the biology and morphometric analysis of rugose spiralling whitefly (RSW), Aleyrodicus rugioperculatus on coconut under mini net house condition at Department of Agricultural Entomology, Tamil Nadu Agricultural University-Coimbatore during 2019-2020. The biology of rugose spiralling whitefly was studied by clip cage method and morphometrics were done using Leica image analyser. Total lifecycle of rugose spiraling whitefly was 56.23 ± 2.20 days. Developmental period of egg, nymphal, pupal and adult period was 8.47 ± 0.26, 17.46 ± 0.76, 10.30 ± 0.29 and 20.00 ± 1.00 days, respectively. In morphometrics, Length and width of egg (0.31 ± 0.01 mm and 0.11± 0.02 mm), nymphal (0.94 ± 0.01 mm and 0.82 ± 0.01 mm), pupal (1.23 ± 0.01 mm and 1.00 ± 0.01 mm) was recorded. A nymphal parasitoid, Encarsia guadeloupae can be potential natural enemy for effective management of rugose spiraling whitefly.

The hidden order behind jerky flow

Jerky flow, or the Portevin-Le Chatelier effect, is investigated at room temperature by applying statistical, multifractal and dynamical analyses to the unstable plastic flow of polycrystalline Al-Mg alloys with different initial microstructures. It is shown that a chaotic regime is found at medium strain rates, whereas a self-organized critical dynamics is observed at high strain rates. The cross-over between these two regimes is signified by a large spread in the multifractal spectrum. Possible physical mechanisms leading to this wealth of patterning behavior and their dependence on the strain rate and the initial microstructure are discussed

A dynamical approach to the spatiotemporal aspects of the Portevin-Le Chatelier effect: Chaos,turbulence and band propagation

Experimental time series obtained from single and poly-crystals subjected to a constant strain rate tests report an intriguing dynamical crossover from a low dimensional chaotic state at medium strain rates to an infinite dimensional power law state of stress drops at high strain rates. We present results of an extensive study of all aspects of the PLC effect within the context a model that reproduces this crossover. A study of the distribution of the Lyapunov exponents as a function of strain rate shows that it changes from a small set of positive exponents in the chaotic regime to a dense set of null exponents in the scaling regime. As the latter feature is similar to the GOY shell model for turbulence, we compare our results with the GOY model. Interestingly, the null exponents in our model themselves obey a power law. The configuration of dislocations is visualized through the slow manifold analysis. This shows that while a large proportion of dislocations are in the pinned state in the chaotic regime, most of them are at the threshold of unpinning in the scaling regime. The model qualitatively reproduces the different types of deformation bands seen in experiments. At high strain rates where propagating bands are seen, the model equations are reduced to the Fisher-Kolmogorov equation for propagative fronts. This shows that the velocity of the bands varies linearly with the strain rate and inversely with the dislocation density, consistent with the known experimental results. Thus, this simple dynamical model captures the complex spatio-temporal features of the PLC effect.Comment: 17 pages, 18 figure