Reflection of solar wind hydrogen from the lunar surface

The solar wind continuously flows out from the Sun and directly interacts with the surfaces of dust and airless planetary bodies throughout the solar system. A significant fraction of solar wind ions reflect from an object's surface as energetic neutral atoms (ENAs). ENA emission from the Moon was first observed during commissioning of the Interstellar Boundary Explorer (IBEX) mission on 3 December 2008. We present the analysis of 10 additional IBEX observations of the Moon while it was illuminated by the solar wind. For the viewing geometry and energy range (> 250 eV) of the IBEX-Hi ENA imager, we find that the spectral shape of the ENA emission from the Moon is well-represented by a linearly decreasing flux with increasing energy. The fraction of the incident solar wind ions reflected as ENAs, which is the ENA albedo and defined quantitatively as the ENA reflection coefficient RN, depends on the incident solar wind speed, ranging from ~0.2 for slow solar wind to ~0.08 for fast solar wind. The average energy per incident solar wind ion that is reflected to space is 30 eV for slow solar wind and 45 eV for fast solar wind. Once ionized, these ENAs can become pickup ions in the solar wind with a unique spectral signature that reaches 3vSW. These results apply beyond the solar system; the reflection process heats plasmas that have significant bulk flow relative to interstellar dust and cools plasmas having no net bulk flow relative to the dust.

The SLC1 high-affinity glutamate and neutral amino acid transporter family

Glutamate transporters play important roles in the termination of excitatory neurotransmission and in providing cells throughout the body with glutamate for metabolic purposes. The high-affinity glutamate transporters EAAC1 (SLC1A1), GLT1 (SLC1A2), GLAST (SLC1A3), EAAT4 (SLC1A6), and EAAT5 (SLC1A7) mediate the cellular uptake of glutamate by the co-transport of three sodium ions (Na(+)) and one proton (H(+)), with the counter-transport of one potassium ion (K(+)). Thereby, they protect the CNS from glutamate-induced neurotoxicity. Loss of function of glutamate transporters has been implicated in the pathogenesis of several diseases, including amyotrophic lateral sclerosis and Alzheimer's disease. In addition, glutamate transporters play a role in glutamate excitotoxicity following an ischemic stroke, due to reversed glutamate transport. Besides glutamate transporters, the SLC1 family encompasses two transporters of neutral amino acids, ASCT1 (SLC1A4) and ASCT2 (SLC1A5). Both transporters facilitate electroneutral exchange of amino acids in neurons and/or cells of the peripheral tissues. Some years ago, a high resolution structure of an archaeal homologue of the SLC1 family was determined, followed by the elucidation of its structure in the presence of the substrate aspartate and the inhibitor d,l-threo-benzyloxy aspartate (d,l-TBOA). Historically, the first few known inhibitors of SLC1 transporters were based on constrained glutamate analogs which were active in the high micromolar range but often also showed off-target activity at glutamate receptors. Further development led to the discovery of l-threo-β-hydroxyaspartate derivatives, some of which effectively inhibited SLC1 transporters at nanomolar concentrations. More recently, small molecule inhibitors have been identified whose structures are not based on amino acids. Activators of SLC1 family members have also been discovered but there are only a few examples known.

Influence of temperature of incubation and type of growth medium on pigmentation in Serratia marcescens.

Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 mug/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.

Study of Heavy-ion Induced Fission for Heavy Element Synthesis

Fission fragment mass distributions were measured in heavy-ion induced fission of 238U. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and quasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model for the reactions of 30Si+238U and 34S+238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of 263,264Sg and 267,268Hs, produced by 30Si+238U and 34S+238U, respectively. It is also suggested that sub-barrier energies can be used for heavy element synthesis.

Separation of the Ribbon from globally distributed energetic neutral Atom Flux using the first five Years of Ibex Observations

The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (~20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and regions of high emissions. We then solve for the globally distributed flux using an interpolation scheme. Previously, ribbon separation techniques were applied to the first year of IBEX-Hi data at and above 0.71 keV. Here we extend the separation analysis down to 0.2 keV and to five years of IBEX data enabling first maps of the ribbon and the globally distributed flux across the full sky of ENA emissions. Our analysis shows the broadening of the ribbon peak at energies below 0.71 keV and demonstrates the apparent deformation of the ribbon in the nose and heliotail. We show global asymmetries of the heliosheath, including both deflection of the heliotail and differing widths of the lobes, in context of the direction, draping, and compression of the heliospheric magnetic field. We discuss implications of the ribbon maps for the wide array of concepts that attempt to explain the ribbon's origin. Thus, we present the five-year separation of the IBEX ribbon from the globally distributed flux in preparation for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.

Imaging the Heliosphere using neutral Atoms from Solar Wind Energy down to 15 eV

We study the spatial and temporal distribution of hydrogen energetic neutral atoms (ENAs) from the heliosheath observed with the IBEX-Lo sensor of the Interstellar Boundary EXplorer (IBEX) from solar wind energies down to the lowest available energy (15 eV). All available IBEX-Lo data from 2009 January until 2013 June were included. The sky regions imaged when the spacecraft was outside of Earth's magnetosphere and when the Earth was moving toward the direction of observation offer a sufficient signal-to-noise ratio even at very low energies. We find that the ENA ribbon—a 20° wide region of high ENA intensities—is most prominent at solar wind energies whereas it fades at lower energies. The maximum emission in the ribbon is located near the poles for 2 keV and closer to the ecliptic plane for energies below 1 keV. This shift is an evidence that the ENA ribbon originates from the solar wind. Below 0.1 keV, the ribbon can no longer be identified against the globally distributed ENA signal. The ENA measurements in the downwind direction are affected by magnetospheric contamination below 0.5 keV, but a region of very low ENA intensities can be identified from 0.1 keV to 2 keV. The energy spectra of heliospheric ENAs follow a uniform power law down to 0.1 keV. Below this energy, they seem to become flatter, which is consistent with predictions. Due to the subtraction of local background, the ENA intensities measured with IBEX agree with the upper limit derived from Lyα observations.

Low Energy Neutral Atoms from the Heliosheath

In the heliosheath beyond the termination shock, low energy (<0.5 keV) neutral atoms are created by charge exchange with interstellar neutrals. Detecting these neutrals from Earth's orbit is difficult because their flux is reduced substantially by ionization losses as they propagate from about 100 to 1 AU and because there are a variety of other signals and backgrounds that compete with this weak signal. Observations from IBEX-Lo and -Hi from two opposing vantage points in Earth's orbit established a lower energy limit of about 0.1 keV on measurements of energetic neutral atoms (ENAs) from the heliosphere and the form of the energy spectrum from about 0.1 to 6 keV in two directions in the sky. Below 0.1 keV, the detailed ENA spectrum is not known, and IBEX provides only upper limits on the fluxes. However, using some assumptions and taking constraints on the spectrum into account, we find indications that the spectrum turns over at an energy between 0.1 and 0.2 keV.

Development of a low energy ion source for ROSINA ion mode calibration

The European Rosetta mission on its way to comet 67P/Churyumov-Gerasimenko will remain for more than a year in the close vicinity (1 km) of the comet. The two ROSINA mass spectrometers on board Rosetta are designed to analyze the neutral and ionized volatile components of the cometary coma. However, the relative velocity between the comet and the spacecraft will be minimal and also the velocity of the outgassing particles is below 1km∕s. This combination leads to very low ion energies in the surrounding plasma of the comet, typically below 20eV. Additionally, the spacecraft may charge up to a few volts in this environment. In order to simulate such plasma and to calibrate the mass spectrometers, a source for ions with very low energies had to be developed for the use in the laboratory together with the different gases expected at the comet. In this paper we present the design of this ion source and we discuss the physical parameters of the ion beam like sensitivity, energy distribution, and beam shape. Finally, we show the first ion measurements that have been performed together with one of the two mass spectrometers.

Kinetic simulation of neutral∕ionized gas and electrically charged dust in the coma of comet 67P∕Churyumov-Gerasimenko

The cometary coma is a unique phenomenon in the solar system being a planetary atmosphere influenced by little or no gravity. As a comet approaches the sun, the water vapor with some fraction of other gases sublimate, generating a cloud of gas, ice and other refractory materials (rocky and organic dust) ejected from the surface of the nucleus. Sublimating gas molecules undergo frequent collisions and photochemical processes in the near‐nucleus region. Owing to its negligible gravity, comets produce a large and highly variable extensive dusty coma with a size much larger than the characteristic size of the cometary nucleus. The Rosetta spacecraft is en route to comet 67P/Churyumov‐Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Both, interpretation of measurements and safety consideration of the spacecraft require modeling of the comet’s dusty gas environment. In this work we present results of a numerical study of multispecies gaseous and electrically charged dust environment of comet Chyuryumov‐Gerasimenko. Both, gas and dust phases of the coma are simulated kinetically. Photolytic reactions are taken into account. Parameters of the ambient plasma as well as the distribution of electric/magnetic fields are obtained from an MHD simulation [1] of the coma connected to the solar wind. Trajectories of ions and electrically charged dust grains are simulated by accounting for the Lorentz force and the nucleus gravity.

Large-scale land acquisitions in Peru: Land (re)-concentration, agrarian change and reactions from rural communities

More than 40 years after the agrarian reform, Peru is experiencing a renewed process of concentration of land ownership in the hands of large-scale investors, favoring the development of a sugar cane production cluster along the northern coast. The expansion of the agricultural frontier by means of large irrigation projects – originally developed to benefit medium- and small-scale farmers – is carried out today in order to be sold to large-scale investors for the production of export crops. In the region of Piura the increasing presence of large-scale biofuel investors puts substantial pressure on land and water resources, not only changing the use of and access to land for local communities, but also generating water shortages vis-à-vis the multiple water demands of local food producers. The changes in land relations and the agro-ecosystem, the altering food production regime as well as the increasing proletarization of smallholders, is driving many locals – even those which (initially) welcomed the investment – into resistance activities against the increasing control of land, water and other natural resources in the hands of agribusinesses. The aim of this presentation is to discuss the contemporary political, social and cultural dynamics of agrarian change along the northern Peruvian coast as well as the «reactions from below» emanating from campesino communities, landless laborers, brick producers, pastoralists as well as other marginalized groups. The different strategies, forms and practices of resistance with the goal of the «protection of the territory» shall be explored as well as the reasons for their rather scattered occurrence and the lack of alliances on the land issue. This input shall make a contribution to the on-going debate on individual and communal property rights and the question of what is best in terms of collective defense against land grabbing.

Impact of Planetary Gravitation on High Precision Neutral Atom Measurements

Measurements of energetic neutral atoms (ENAs) have been extremely successful in providing very important information on the physical processes inside and outside of our heliosphere. For instance, recent Interstellar Boundary Explorer (IBEX) observations have provided new insights into the local interstellar environment and improved measurements of the interstellar He temperature, velocity, and direction of the interstellar flow vector. Since particle collisions are rare, and radiation pressure is negligible for these neutrals, gravitational forces mainly determine the trajectories of neutral He atoms. Depending on the distance of an ENA to the source of a gravitational field and its relative speed and direction, this can result in significant deflection and acceleration. In this paper, we investigate the impact of the gravitational effects of Earth, the Moon, and Jupiter on ENA measurements performed in Earth's orbit. The results show that current analysis of the interstellar neutral parameters by IBEX is not significantly affected by planetary gravitational effects. We further studied the possibility of whether or not the Helium focusing cone of the Sun and Jupiter could be measured by IBEX and whether or not these cones could be used as an independent measure of the temperature of interstellar Helium.

Interstellar Flow and Temperature Determination with IBEX: Robustness and Sensitivity to Systematic Effects

The Interstellar Boundary Explorer (IBEX) samples the interstellar neutral (ISN) gas flow of several species every year from December through late March when the Earth moves into the incoming flow. The first quantitative analyses of these data resulted in a narrow tube in four-dimensional interstellar parameter space, which couples speed, flow latitude, flow longitude, and temperature, and center values with approximately 3° larger longitude and 3 km s⁻¹ lower speed, but with temperatures similar to those obtained from observations by the Ulysses spacecraft. IBEX has now recorded six years of ISN flow observations, providing a large database over increasing solar activity and using varying viewing strategies. In this paper, we evaluate systematic effects that are important for the ISN flow vector and temperature determination. We find that all models in use return ISN parameters well within the observational uncertainties and that the derived ISN flow direction is resilient against uncertainties in the ionization rate. We establish observationally an effective IBEX-Lo pointing uncertainty of ±0°18 in spin angle and confirm an uncertainty of ±0°1 in longitude. We also show that the IBEX viewing strategy with different spin-axis orientations minimizes the impact of several systematic uncertainties, and thus improves the robustness of the measurement. The Helium Warm Breeze has likely contributed substantially to the somewhat different center values of the ISN flow vector. By separating the flow vector and temperature determination, we can mitigate these effects on the analysis, which returns an ISN flow vector very close to the Ulysses results, but with a substantially higher temperature. Due to coupling with the ISN flow speed along the ISN parameter tube, we provide the temperature Tvisn∞=8710+440/-680 K for Visn∞=26 km s⁻¹ for comparison, where most of the uncertainty is systematic and likely due to the presence of the Warm Breeze.

DNA-DAMAGING REACTIONS OF NEOCARZINOSTATIN (ANTIBIOTICS, DNA REPAIR, CYTOTOXICITY)

Sensitive assays utilizing a cell-free and an intracellular system were employed to study the molecular bases of the DNA-damaging reactions of neocarzinostatin (NCS). In the cell-free DNA system, super-helical form I DNA from the bacteriophage PM2 was used as the substrate. The three forms of DNA present after treatment with NCS were separated by agarose gel electrophoresis. When NCS-damaged DNA was assayed under neutral conditions, there was a progressive decrease in the amount of surviving form I DNA and a corresponding increase in form II (nicked, relaxed circular) DNA, but very little increase in form III (linear duplex) DNA. This indicates that NCS introduces primarily single-strand breaks. However later studies showed that there were some site-specific double-strand breaks mediated by NCS on PM2 DNA. Seven such specific sites were mapped on the PM2 genome. When the damage was assayed under nondenaturing alkaline conditions or with the apurinic/apyrimidinic endonuclease IV, there was a slightly greater decrease in the amount of surviving form I DNA compared with neutral conditions indicating the presence of some alkali-labile sites.^ NCS-mediated DNA damage and repair were examined with cultured Chinese hamster ovary (CHO) cells using either alkaline elution for analysis of single-strand breaks or neutral elution for analysis of double-strand breaks. Most of the strand breaks introduced by NCS were capable of being rejoined. However, there was a small amount of residual DNA damage remaining unrejoined at 24-hr after removal of the drug. The amount of residual DNA damage was higher in a CHO mutant cell line (EM9) having a higher sensitivity to killing by NCS than its parental strain (AA8). Other lesions, DNA-protein complexes and alkali-labile sites, were detected after NCS treatment but they constituted only a small fraction of the DNA damage.^ Based on the above information, it can be postulated that NCS introduces some very lethal DNA damage. It is likely that the lethal lesions are a subset of the total DNA lesions representing the residual DNA damage. This DNA damage may be composed of site-specific, unrejoinable double-strand breaks and are thus the primary lesion leading to NCS-mediated lethality.^

Ion concentration and deduced chemical compounds of the GRIP and Dome Fuji ice cores, Greenland and Antarctica

We have proposed a method of deducing the chemical compounds found in deep polar ice cores by analyzing the balance between six major ions (Cl-, NO3-, SO4**2-, Na+, Mg2+, and Ca2+). The method is demonstrated for the Holocene and last glacial maximum regions of the Dome Fuji and GRIP ice cores. The dominant compounds depend only on the ion balance and the sequence of chemical reactions. In priority order, the principle salts are calcium sulfate, other sulfates, nitrate, chloride, and carbonate. The chemical abundances deduced by this method agree well with the results of Raman spectroscopy on individual salt inclusions. The abundances in the ice cores are shown to reflect differences in climatic periods (the acidic environment of the Holocene versus the reductive environment of the last glacial maximum) and regional conditions (the marine environment of Antarctica versus the continental environment of Greenland).

Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis

Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 µatm) and temperature (15, 30 °C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1-3 days) to elevated pCO2 except absorption efficiency at 15 °C and 30 °C, and respiration rate and excretion rate at 15 °C. The percentage change in the physiological rates ranged from 0% to 90% at 15 °C and from 0% to 73% at 30 °C when pCO2 was increased from 380 µatm to 1250 µatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion. When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24 °C to 30 °C but the rates at 15 °C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world.