Analysis of the phenomenon of speculative trading in one of its basic manifestations: postage stamp bubbles

We document and analyze the empirical facts concerning one of the clearest evidence of speculation in financial trading as observed in the postage collection stamp market. We unravel some of the mechanisms of speculative behavior which emphasize the role of fancy and collective behavior. In our conclusion, we propose a classification of speculative markets based on two parameters, namely the amplitude of the price peak and a second parameter that measures its ``sharpness''. This study is offered to anchor modeling efforts to realistic market constraints and observations.Comment: 9 pages, 5 figures and 2 tables, in press in Int. J. Mod. Phys.

Monosynaptic Functional Connectivity in Cerebral Cortex During Wakefulness and Under Graded Levels of Anesthesia

The balance between excitation and inhibition is considered to be of significant importance for neural computation and cognitive function. Excitatory and inhibitory functional connectivity in intact cortical neuronal networks in wakefulness and graded levels of anesthesia has not been systematically investigated. We compared monosynaptic excitatory and inhibitory spike transmission probabilities using pairwise cross-correlogram (CCG) analysis. Spikes were measured at 64 sites in the visual cortex of rats with chronically implanted microelectrode arrays during wakefulness and three levels of anesthesia produced by desflurane. Anesthesia decreased the number of active units, the number of functional connections, and the strength of excitatory connections. Connection probability (number of connections per number of active unit pairs) was unaffected until the deepest anesthesia level, at which a significant increase in the excitatory to inhibitory ratio of connection probabilities was observed. The results suggest that the excitatory–inhibitory balance is altered at an anesthetic depth associated with unconsciousness

Intrinsic Noise in Cultured Hippocampal Neurons: Experiment and Modeling

Ion channels open and close stochastically. The fluctuation of these channels represents an intrinsic source of noise that affects the input-output properties of the neuron. We combined whole-cell measurements with biophysical modeling to characterize the intrinsic stochastic and electrical properties of single neurons as observed at the soma. We measured current and voltage noise in 18 d postembryonic cultured neurons from the rat hippocampus, at various subthreshold and near-threshold holding potentials in the presence of synaptic blockers. The observed current noise increased with depolarization, as ion channels were activated, and its spectrum demonstrated generalized 1/fbehavior. Exposure to TTX removed a significant contribution from Na^+ channels to the noise spectrum, particularly at depolarized potentials, and the resulting spectrum was now dominated by a single Lorentzian (1/f^2) component. By replacing the intracellular K^+ with Cs^+, we demonstrated that a major portion of the observed noise was attributable to K^+ channels. We compared the measured power spectral densities to a 1-D cable model of channel fluctuations based on Markov kinetics. We found that a somatic compartment, in combination with a single equivalent cylinder, described the effective geometry from the viewpoint of the soma. Four distinct channel populations were distributed in the membrane and modeled as Lorentzian current noise sources. Using the NEURON simulation program, we summed up the contributions from the spatially distributed current noise sources and calculated the total voltage and current noise. Our quantitative model reproduces important voltage- and frequency-dependent features of the data, accounting for the 1/f behavior, as well as the effects of various blockers

Feed Intake, Digestibility and Growth Performance of Horro Lambs Fed Natural Pasture Hay Supplemented Graded Level of Vernonia amygdalina Leaves and Sorghum Grain Mixture

No Abstract

A Study on the Physicochemical Properties of the Selected Ponds of Patna Town, Bihar, India

With the progress of the urbanization and industrialization, many types of water pollutants (such as pesticide, heavy metals, detergents, municipal wastes, domestic wastes and fertilizers) were generated. These pollutants were distributed into the environment by the different sources. These pollutants were distributed into the environment by the different sources. In this research paper, physicochemical characteristic of water samples from selected ponds in and around Patna, Bihar has been studied. The parameters observed were Temperature, pH, Electrical conductivity, Calcium, Phosphate, Total Hardness, Alkalinity, Chloride, Dissolved oxygen, Free CO2 and Nitrate. It can be concluded that the water parameters which were taken for the present study were above the pollution level of surface water which does not satisfy their requirement for the use of various purposes. In this investigation, a brief attempt has been made to study the extent of change in the quality of water in comparison to water quality standards of World Health Organization (WHO)

Local Field Potentials Encode Place Cell Ensemble Activation during Hippocampal Sharp Wave Ripples

Whether the activation of spiking cell ensembles can be encoded in the local field potential (LFP) remains unclear. We address this question by combining in vivo electrophysiological recordings in the rat hippocampus with realistic biophysical modeling, and explore the LFP of place cell sequence spiking (“replays”) during sharp wave ripples. We show that multi-site perisomatic LFP amplitudes, in the ∼150–200 Hz frequency band, reliably reflect spatial constellations of spiking cells, embedded within non-spiking populations, and encode activation of local place cell ensembles during in vivo replays. We find spatiotemporal patterns in the LFP, which remain consistent between sequence replays, in conjunction with the ordered activation of place cell ensembles. Clustering such patterns provides an efficient segregation of replay events from non-replay-associated ripples. This work demonstrates how spatiotemporal ensemble spiking is encoded extracellularly, providing a window for efficient, LFP-based detection and monitoring of structured population activity in vivo

Bioaktivitas Ekstrak Daun Jeruk Purut (Citrus Hystrix Dc) terhadap Rayap Tanah (Coptotermes Curvignathus Holmgren)

Kaffir lime leaves (Citrus hystrix DC) has the potential to be used as a natural preservative especially an anti-termites. The study aims to evaluation the toxicity of extract of leaves C. hystrix against subterranean termites Coptotermes curvignathus Holmgren and to determine the optimal concentration of extract lime leaves on subterranean termite activity. Lime leaves were extracted using maceration method with methanol. Level of concentration were 0%, 2%, 4%, 6%, 8% and 10%. Filter paper soaked at each concentration thengive as a food source to subterranean termites. Bioassay tests were carried out for 21 days. Then mortality and filter paper weight loss was measured. The results showed the concentration level of 10% has the highest termite mortality with average value of 100% and has the lowest value of filter paper weight loss with a average value 13.48%. However, the optimal concentration was achieved at 8% due to the mortality rate reached 94% and the level of termite activity was classified as very strong. Keyword: Bioactivity anti-termites Citrus hystrix DC, Coptotermes curvignathus Holmgren, Methanol extract

Internal dose assessment for environmental monitoring in nuclear power plant accidents

A method for exploiting human's internal contamination data for radioactive release estimation in nuclear power plant accidents is proposed. Nevertheless, such data is often very rough and uncertain; it is accessible even in toughest situations when most of the active and passive monitors are damaged by the accident. These data can be used in combination with other collectable data for estimating the event scale in severe nuclear power plan accidents. The rationale behind the method is that nuclear power plant accidents are often associated with internal contamination of radiation workers involved in the early stages of emergency response activities mainly due to the release of 131I in atmosphere. The proposed inverse analytical approach uses the 131I intake of contaminated workers, their working conditions, chronology of events, and applied personal safety measures during the first hours or days of the emergency response activities to estimate the magnitude of 131I concentration in the air