Extensive population synthesis of isolated neutron stars with field decay

We perform population synthesis studies of different types of neutron stars taking into account the magnetic field decay. For the first time, we confront our results with observations using {\it simultaneously} the Log N -- Log S distribution for nearby isolated neutron stars, the Log N -- Log L distribution for magnetars, and the distribution of radio pulsars in the $P$ -- $\dot P$ diagram. We find that our theoretical model is consistent with all sets of data if the initial magnetic field distribution function follows a log-normal law with $\sim 13.25$ and $\sigma_{\log B_0}\sim 0.6$. The typical scenario includes about 10% of neutron stars born as magnetars, significant magnetic field decay during the first million years of a NS life. Evolutionary links between different subclasses may exist, although robust conclusions are not yet possible. We apply the obtained field distribution and the model of decay to study long-term evolution of neuton stars till the stage of accretion from the interstellar medium. It is shown that though the subsonic propeller stage can be relatively long, initially highly magnetized neutron stars ($B_0 > \sim 10^{13}$ G) reach the accretion regime within the Galactic lifetime if their kick velocities are not too large. The fact that in previous studies made $>$10 years ago, such objects were not considered results in a slight increase of the Accretor fraction in comparison with earlier conclusions. Most of the neutron stars similar to the Magnificent seven are expected to become accreting from the interstellar medium after few billion years of their evolution. They are the main predecestors of accreting isolated neutron stars.Comment: 4 pages, conference "Astrophysics of Neutron Stars - 2010" in honor of M. Ali Alpar, Izmir, Turke

Fate of trace organic compounds in hyporheic zone sediments of contrasting organic carbon content and impact on the microbiome

The organic carbon in streambed sediments drives multiple biogeochemical reactions, including the attenuation of organic micropollutants. An attenuation assay using sediment microcosms differing in the initial total organic carbon (TOC) revealed higher microbiome and sorption associated removal efficiencies of trace organic compounds (TrOCs) in the high-TOC compared to the low-TOC sediments. Overall, the combined microbial and sorption associated removal efficiencies of the micropollutants were generally higher than by sorption alone for all compounds tested except propranolol whose removal efficiency was similar via both mechanisms. Quantitative real-time PCR and time-resolved 16S rRNA gene amplicon sequencing revealed that higher bacterial abundance and diversity in the high-TOC sediments correlated with higher microbial removal efficiencies of most TrOCs. The bacterial community in the high-TOC sediment samples remained relatively stable against the stressor effects of TrOC amendment compared to the low-TOC sediment community that was characterized by a decline in the relative abundance of most phyla except Proteobacteria. Bacterial genera that were significantly more abundant in amended relative to unamended sediment samples and thus associated with biodegradation of the TrOCs included Xanthobacter, Hyphomicrobium, Novosphingobium, Reyranella and Terrimonas. The collective results indicated that the TOC content influences the microbial community dynamics and associated biotransformation of TrOCs as well as the sorption potential of the hyporheic zone sediments

Biodegradation of metoprolol in oxic and anoxic hyporheic zone sediments: unexpected effects on microbial communities

Metoprolol is widely used as a beta-blocker and considered an emerging contaminant of environmental concern due to pseudo persistence in wastewater effluents that poses a potential ecotoxicological threat to aquatic ecosystems. Microbial removal of metoprolol in the redox-delineated hyporheic zone (HZ) was investigated using streambed sediments supplemented with 15 or 150 μM metoprolol in a laboratory microcosm incubation under oxic and anoxic conditions. Metoprolol disappeared from the aqueous phase under oxic and anoxic conditions within 65 and 72 days, respectively. Metoprolol was refed twice after initial depletion resulting in accelerated disappearance under both conditions. Metoprolol disappearance was marginal in sterile control microcosms with autoclaved sediment. Metoprolol was transformed mainly to metoprolol acid in oxic microcosms, while metoprolol acid and α-hydroxymetoprolol were formed in anoxic microcosms. Transformation products were transient and disappeared within 30 days under both conditions. Effects of metoprolol on the HZ bacterial community were evaluated using DNA- and RNA-based time-resolved amplicon Illumina MiSeq sequencing targeting the 16S rRNA gene and 16S rRNA, respectively, and were prominent on 16S rRNA rather than 16S rRNA gene level suggesting moderate metoprolol-induced activity-level changes. A positive impact of metoprolol on Sphingomonadaceae and Enterobacteriaceae under oxic and anoxic conditions, respectively, was observed. Nitrifiers were impaired by metoprolol under oxic and anoxic conditions. Collectively, our findings revealed high metoprolol biodegradation potentials in the hyporheic zone under contrasting redox conditions associated with changes in the active microbial communities, thus contributing to the attenuation of micropollutants

Space cowboys odyssey: beyond the Gould Belt

We present our new advanced model for population synthesis of close-by cooling NSs. Detailed treatment of the initial spatial distribution of NS progenitors and a detailed ISM structure up to 3 kpc give us an opportunity to discuss the strategy to look for new isolated cooling NSs. Our main results in this respect are the following: new candidates are expected to be identified behind the Gould Belt, in directions to rich OB associations, in particular in the Cygnus-Cepheus region; new candidates, on average, are expected to be hotter than the known population of cooling NS. Besides the usual approach (looking for soft X-ray sources), the search in 'empty' $\gamma$-ray error boxes or among run-away OB stars may yield new X-ray thermally emitting NS candidates.Comment: 3 pages, 2 figures, proceedings of the conference "40 Years of Pulsars ", 12-17 August 2007, Montreal, Canad

Ibuprofen Degradation and Associated Bacterial Communities in Hyporheic Zone Sediments

Ibuprofen, a non-steroidal anti-inflammatory pain reliever, is among pharmaceutical residues of environmental concern ubiquitously detected in wastewater effluents and receiving rivers. Thus, ibuprofen removal potentials and associated bacteria in the hyporheic zone sediments of an impacted river were investigated. Microbially mediated ibuprofen degradation was determined in oxic sediment microcosms amended with ibuprofen (5, 40, 200, and 400 µM), or ibuprofen and acetate, relative to an un-amended control. Ibuprofen was removed by the original sediment microbial community as well as in ibuprofen-enrichments obtained by re-feeding of ibuprofen. Here, 1-, 2-, 3-hydroxy- and carboxy-ibuprofen were the primary transformation products. Quantitative real-time PCR analysis revealed a significantly higher 16S rRNA abundance in ibuprofen-amended relative to un-amended incubations. Time-resolved microbial community dynamics evaluated by 16S rRNA gene and 16S rRNA analyses revealed many new ibuprofen responsive taxa of the Acidobacteria, Actinobacteria, Bacteroidetes, Gemmatimonadetes, Latescibacteria, and Proteobacteria. Two ibuprofen-degrading strains belonging to the genera Novosphingobium and Pseudomonas were isolated from the ibuprofen-enriched sediments, consuming 400 and 300 µM ibuprofen within three and eight days, respectively. The collective results indicated that the hyporheic zone sediments sustain an efficient biotic (micro-)pollutant degradation potential, and hitherto unknown microbial diversity associated with such (micro)pollutant removal

X-ray analysis of the proper motion and pulsar wind nebula for PSR J1741-2054

We obtained six observations of PSR J1741-2054 using the $Chandra$ ACIS-S detector totaling $\sim$300 ks. By registering this new epoch of observations to an archival observation taken 3.2 years earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at $\mu =109 \pm 10 {\rm mas\ yr}^{-1}$ in a direction consistent with the symmetry axis of the observed H$\alpha$ nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index $\Gamma$=2.68$\pm$0.04, plus a blackbody with an emission radius of (4.5$^{+3.2}_{-2.5})d_{0.38}$ km, for a DM-estimated distance of $0.38d_{0.38}$ kpc and a temperature of $61.7\pm3.0$ eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of $\Gamma$ = 1.67$\pm$0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.Comment: 7 pages, 8 figures, 4 Tables; Accepted by Ap

Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54

We report on Chandra X-ray Observatory (CXO) observations of the pulsar wind nebula (PWN) associated with PSR B0355+54 (eight observations with a 395 ks total exposure, performed over an 8 month period). We investigated the spatial and spectral properties of the emission coincident with the pulsar, compact nebula (CN), and extended tail. We find that the CN morphology can be interpreted in a way that suggests a small angle between the pulsar spin axis and our line-of-sight, as inferred from the radio data. On larger scales, emission from the 7' (2 pc) tail is clearly seen. We also found hints of two faint extensions nearly orthogonal to the direction of the pulsar's proper motion. The spectrum extracted at the pulsar position can be described with an absorbed power-law + blackbody model. The nonthermal component can be attributed to magnetospheric emission, while the thermal component can be attributed to emission from either a hot spot (e.g., a polar cap) or the entire neutron star surface. Surprisingly, the spectrum of the tail shows only a slight hint of cooling with increasing distance from the pulsar. This implies either a low magnetic field with fast flow speed, or particle re-acceleration within the tail. We estimate physical properties of the PWN and compare the morphologies of the CN and the extended tail with those of other bow shock PWNe observed with long CXO exposures.Comment: 11 pages, 8 figure

Technical Performance and Energy Intensity of the Electrode-Separator Composite Manufacturing Process

AbstractEnergy storage is one of the key technological factors that determine the success of a sustainable future. Especially green mobility concepts for electric or hybrid electric vehicles highly depend upon storage technologies with high energy density and light-weight materials. At the same time, innovative production processes should be conceived that ensure energy and resource efficient manufacturing of these energy storage devices. This paper focuses on the technical as well as dynamic energetic performance analysis and evaluation of an innovative electrode-separator composite manufacturing process of lithium-ion batteries for automotive applications. The technical performance indicators such as battery capacity and the energy intensity of the manufacturing process are highly dependent upon process parameters, machine and product design. Hence, in-depth process knowledge must be acquired to understand interdependencies between all system components. Thus, the manufacturing process is analysed in terms of its dynamics, and correlations between process parameters, process energy demand and final product properties are assessed. The resulting knowledge is important for the subsequent design of large-scale products and processes involved design, as well as for characterisation of the manufacturing process for life cycle inventory databases or life cycle costing calculations