PAMELA observational capabilities of Jovian electrons

PAMELA is a satellite-borne experiment that has been launched on June 15th, 2006. It is designed to make long duration measurements of cosmic radiation over an extended energy range. Specifically, PAMELA is able to measure the cosmic ray antiproton and positron spectra over the largest energy range ever achieved and will search for antinuclei with unprecedented sensitivity. Furthermore, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with solar and earth physics. The apparatus consists of: a time of flight system, a magnetic spectrometer, an electromagnetic imaging calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. In this work a study of the PAMELA capabilities to detect electrons is presented. The Jovian magnetosphere is a powerful accelerator of electrons up to several tens of MeV as observed at first by Pioneer 10 spacecraft (1973). The propagation of Jovian electrons to Earth is affected by modulation due to Corotating Interaction Regions (CIR). Their flux at Earth is, moreover, modulated because every 13 months Earth and Jupiter are aligned along the average direction of the Parker spiral of the Interplanetary Magnetic Field.PAMELA will be able to measure the high energy tail of the Jovian electrons in the energy range from 50 up to 130 MeV. Moreover, it will be possible to extract the Jovian component reaccelerated at the solar wind termination shock (above 130 MeV up to 2 GeV) from the galactic flux.     

Presynaptic transporter-mediated release of glutamate evoked by the protonophore FCCP increases under altered gravity conditions

High-affinity Na⁺-dependent glutamate transporters of the plasma membrane mediate the glutamate uptake into neurons, and thus maintain low levels of extracellular glutamate in the synaptic cleft. The study focused on the release of glutamate by reversal of Na⁺-dependent glutamate transporters from rat brain nerve terminals (synaptosomes) under conditions of centrifuge-induced hypergravity. Flow cytometric analysis revealed similarity in the size and cytoplasmic granularity between synaptosomal preparations obtained from control and G-loaded animals (10 G, 1 h). The release of cytosolic l-[¹⁴C]glutamate from synaptosomes was evaluated using the protonophore FCCP, which dissipated synaptic vesicle proton gradient, thus synaptic vesicles were not able to keep glutamate inside and the latter enriched cytosol. FCCP per se induced the greater release of l-[¹⁴C]glutamate in hypergravity as compared to control (4.8 ± 1.0% and 8.0 ± 1.0% of total label). Exocytotic release of l-[¹⁴C]glutamate evoked by depolarization was reduced down to zero after FCCP application under both conditions studied. Depolarization stimulated release of cytosolic l-[¹⁴C]glutamate from synaptosomes preliminary treated with FCCP was considerably increased from 27.0 ± 2.2% of total label in control to 35.0 ± 2.3% in hypergravity. Non-transportable inhibitor of glutamate transporter dl-threo-β-benzyloxyaspartate was found to significantly inhibit high-KCl and FCCP-stimulated release of l-[¹⁴C]glutamate, confirming the release by reversal of glutamate transporters. The enhancement of transporter-mediated release of glutamate in hypergravity was found to result at least partially from the inhibition of the activity of Na/K-ATPase in the plasma membrane of synaptosomes. We suggested that hypergravity-induced alteration in transporter-mediated release of glutamate indicated hypoxic injury of neurons.     

Development of thermal sensors and drilling systems for lunar and planetary regoliths

We consider some novel concepts for thermal properties experiments aboard lunar landers or rovers, that may lead to an improved understanding of both the structure of the lunar near surface layers and the lunar thermal history. The new instruments could be developed using the experience and heritage from recently developed systems, like the Rosetta Lander thermal conductivity experiment MUPUS and existing designs used for terrestrial measurements of thermal conductivity. We describe shortly the working principle of such sensors and the main challenges faced when using them in the airless regolith layers of the Moon or other airless bodies. In addition new concepts to create appropriate drill holes for thermal and other measurements in the lunar regolith are discussed.     

Host–parasite interactions in closed and open microbial cultivation system

The study addresses interaction of bacteria and phages in the host–parasite system in batch and continuous cultures. The study system consists of the auxotrophic strain of Brevibacterium – Brevibacterium sp. 22L – and the bacteriophage of Brevibacterium sp., isolated from the soil by the enrichment method.

1.

Closed system. In the investigation of the relationship between the time of bacterial lysis and multiplicity of phage infection it has been found that at a lower phage amount per cell it takes a longer time for the lysis of the culture to become discernible. Another important factor determining cytolysis in liquid medium is the physiological state of bacterial population. Specific growth rate of bacteria at the moment of phage infection has been chosen as an indicator of the physiological state of bacteria. It has been shown that the shortest latent period and the largest output of the phage are observed during the logarithmic growth phase of bacteria grown under favorable nutrient conditions. In the stationary phase, bacterial cells become “a bad host” for the phage, whose reproduction rate decreases, and the lysis either slows down significantly or does not occur at all.     

Instability of the present LEO satellite populations

Several studies conducted during 1991–2001 demonstrated, with some assumed launch rates, the future unintended growth potential of the Earth satellite population, resulting from random, accidental collisions among resident space objects. In some low Earth orbit (LEO) altitude regimes where the number density of satellites is above a critical spatial density, the production rate of new breakup debris due to collisions would exceed the loss of objects due to orbital decay.     

Aerosols and clouds in the upper troposphere–lower stratosphere region detected by GOMOS and ACE: Intercomparison and analysis of the years 2004 and 2005

Satellite-based limb occultation measurements are well suited for the detection and mapping of polar stratospheric clouds (PSCs) and cirrus clouds. PSCs are of fundamental importance for the formation of the Antarctic ozone hole that occurs every year since the early 1980s in Southern Hemisphere spring. Despite progress in the observation, modeling and understanding of PSCs in recent years, there are still important questions which remain to be resolved, e.g. PSC microphysics, composition, formation mechanisms and long-term changes in occurrence. In addition, it has recently become clear that cirrus clouds significantly affect the global energy balance and climate, due to their influence on atmospheric thermal structure.     

Instantaneous Frequency Estimation Using Adaptive Linear Predictor Weights

A computationally efficient scheme for estimating the digital instantaneous frequencies of narrowband inputs is introduced. The frequency estimates are obtained by searching for minima of the inverse input power spectrum. This spectrum is estimated at each input sample from the weights of an adaptive linear predictor which uses the LMS (least mean square) algorithm to update its weights. The related minima are sought via an iterative search algorithm, referred to as the iterative frequency estimator. This algorithm is computationally more efficient than available methods, and also provides a higher resolution. Simulation results are included; these include tracking of random message sequences in FM signals, and the formant frequency estimation of speech.