Coupled oscillators as models of phantom and scalar field cosmologies

We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature, and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model.Comment: 18 pages, LaTeX, to appear in Physical Review

The mother – child nexus. Knowledge and valuation of wild food plants in Wayanad, Western Ghats, India

This study focuses on the mother-child nexus (or process of enculturation) with respect to knowledge and valuation of wild food plants in a context where accelerated processes of modernization and acculturation are leading to the erosion of knowledge and cultural values associated with wild food plant use, in Wayanad, Western Ghats, India. Wild food plants in this biodiversity hotspot form an important part of local diets and are used as famine foods and medicines. In general, the collection and consumption of these foods are increasingly stigmatized as symbols of poverty and 'tribalness' (equivalent to 'backwardness'). The study, which falls within the discipline of ethnobotany, involves three socio-cultural groups – the Paniya and Kuruma tribes and non-tribals. Further, it examines the impact in the enculturation process of an unusual educational programme sponsored by the MS Swaminathan Research Foundation that is oriented towards creating awareness among children of cultural identity and local biological resources – the study compares children having participated in the programme with those who have not, with their mothers. The process of enculturation is assessed by comparing wild food plant knowledge and values between mothers and their children, and by examining events where knowledge transmission occurs, including collection and consumption. For that, quantitative and qualitative data collection and analysis tools were used, and methods included semi-structured interviews, photo identification and informal interviews of key informants. Results ratify that women are the knowledge holders and are the primary means of knowledge transmission to their children. Nevertheless, fewer children are collecting wild food plants with mothers and learning about them, apparently because of children's lack of time. On the other hand, older people acknowledge that a "change in taste" is occurring among younger generations. In general, there is a simultaneous transmission from mothers to children of contrasting values pertaining to wild food plants: that they are 'good food' but also that they are symbols of low status and poverty, leading to feelings of shame and inferiority. Finally, the study concludes that the educational programme, through a "learning by doing" approach counteracts social stigma and encourages learning among children of all ages and socio-cultural groups, particularly stimulating non-tribal children to learn from tribals

Chaos in nonlinear oscillations: controlling and synchronization

This book deals with the bifurcation and chaotic aspects of damped and driven nonlinear oscillators. The analytical and numerical aspects of the chaotic dynamics of these oscillators are covered, together with appropriate experimental studies using nonlinear electronic circuits. Recent exciting developments in chaos research are also discussed, such as the control and synchronization of chaos and possible technological applications

Heightened Delta Power during Slow-Wave-Sleep in Patients with Rett Syndrome Associated with Poor Sleep Efficiency.

Sleep problems are commonly reported in Rett syndrome (RTT); however the electroencephalographic (EEG) biomarkers underlying sleep dysfunction are poorly understood. The aim of this study was to analyze the temporal evolution of quantitative EEG (qEEG) biomarkers in overnight EEGs recorded from girls (2-9 yrs. old) diagnosed with RTT using a non-traditional automated protocol. In this study, EEG spectral analysis identified high delta power cycles representing slow wave sleep (SWS) in 8-9h overnight sleep EEGs from the frontal, central and occipital leads (AP axis), comparing age-matched girls with and without RTT. Automated algorithms quantitated the area under the curve (AUC) within identified SWS cycles for each spectral frequency wave form. Both age-matched RTT and control EEGs showed similar increasing trends for recorded delta wave power in the EEG leads along the antero-posterior (AP). RTT EEGs had significantly fewer numbers of SWS sleep cycles; therefore, the overall time spent in SWS was also significantly lower in RTT. In contrast, the AUC for delta power within each SWS cycle was significantly heightened in RTT and remained heightened over consecutive cycles unlike control EEGs that showed an overnight decrement of delta power in consecutive cycles. Gamma wave power associated with these SWS cycles was similar to controls. However, the negative correlation of gamma power with age (r = -.59; p<0.01) detected in controls (2-5 yrs. vs. 6-9 yrs.) was lost in RTT. Poor % SWS (i.e., time spent in SWS overnight) in RTT was also driven by the younger age-group. Incidence of seizures in RTT was associated with significantly lower number of SWS cycles. Therefore, qEEG biomarkers of SWS in RTT evolved temporally and correlated significantly with clinical severity

Comparison of control EEGs’ and RTT EEGs’ delta power.

<p>(A) Representative 8.5 hour EEG traces were scored as high delta power (black) and low delta power (grey). Comparison of RTT EEG with control EEGs revealed significantly higher delta power as well as fewer cycles. (B) RTT EEGs had significantly greater delta power in all three lead positions (frontal, central, occipital). (C) Patients with RTT had no significant difference in gamma power but revealed a trend of greater power reading in all three lead positions compared to control group.</p

Clinical severity scores.

<p>Severity Score = SS; SZ = seizures; Mild = 0–7; Moderate = 8–14; Severe = 15–21.</p><p>Clinical severity scores.</p

SWS percent in Age Group.

<p>Patients with RTT have significantly lower SWS percent compared to control group. Significance is driven in the age group 2–5 year old. The significance in SWS percent is lost in 6–9 years ago. Comparison of SWS percent reveals an increasing tread in SWS percent for patients with RTT instead of the decreasing trend in the control group.</p

Age-dependent evolution.

<p>Because occipital lead displayed the greater difference between genotypes, occipital line graphs were used to display age related comparison. (A) Comparison of delta power revealed no significant difference between ages. Difference in delta power between Control EEGs and RTT EEGs seems to be driven by 2–5 year age group. (B) Gamma power in control group had a significant decrease from age group 2–5 year to 6–9 year group. The sharp decrease in gamma power is lost in patients with RTT as age increases.</p