Local Mapping of Polar Ionospheric Electrodynamics

An accurate description of the state of the ionosphere is crucial for understanding the physics of Earth's coupling to space, including many potentially hazardous space weather phenomena. To support this effort, ground networks of magnetometer stations, optical instruments, and radars have been deployed. However, the spatial coverage of such networks is naturally restricted by the distribution of land mass and access to necessary infrastructure. We present a new technique for local mapping of polar ionospheric electrodynamics, for use in regions with high data density, such as Fennoscandia and North America. The technique is based on spherical elementary current systems (SECS), which were originally developed to map ionospheric currents. We expand their use by linking magnetic field perturbations in space and on ground, convection measurements from space and ground, and conductance measurements, via the ionospheric Ohm's law. The result is a technique that is similar to the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique, but tailored for regional analyses of arbitrary spatial extent and resolution. We demonstrate our technique on synthetic data, and with real data from three different regions. We also discuss limitations of the technique and potential areas for improvement.publishedVersio

Anion exchange membrane soil nitrate predicts turfgrass color and yield.

Desirable nitrogen (N) management practices for turfgrass supply sufficient N for high quality turf while limiting excess soil N. Previous studies suggested the potential of anion exchange membranes (AEMs) for predicting turfgrass color, quality, or yield. However, these studies suggested a wide range of critical soil nitrate-nitrogen (NO3-N) values across sample dates. A field experiment, in randomized complete block design with treatments consisting of nine N application rates, was conducted on a mixed species cool-season turfgrass lawn across two growing seasons. Every 2 wk from May to October, turfgrass color was assessed with three different reflectance meters, and soil NO3-N was measured with in situ AEMs. Cate-Nelson models were developed comparing relative reflectance value and yield to AEM desorbed soil NO3-N pooled across all sample dates. These models predicted critical AEM soil NO3-N values from 0. 45 to 1.4 micro g cm-2 d-1. Turf had a low probability of further positive response to AEM soil NO3-N greater than these critical values. These results suggest that soil NO3-N critical values from AEMs may be applicable across sample dates and years and may serve to guide N fertilization to limit excess soil NO3-N

Cultural orientations and preference for HRM policies and practices:the case of Oman

This study empirically examines the influence of cultural orientations on employee preferences of human resource management (HRM) policies and practices in Oman. Data were collected from 712 employees working in six large Omani organizations. The findings indicate that there is a number of differences among Omani employees regarding value orientations due especially to age, education and work experience. The findings show a strong orientation towards mastery, harmony, thinking and doing, and a weak orientation towards hierarchy, collectivism, subjugation and human nature-as-evil. The results demonstrate a clear link between value orientations and preferences for particular HRM policies and practices. Group-oriented HRM practices are preferred by those who scored high on collectivism and being orientations, and those who scored low on thinking and doing orientations. Hierarchy-oriented HRM practices are preferred by those scoring high on hierarchy, subjugation and human nature-as-bad orientations, and those scoring low on thinking and mastery orientations. Finally, preference for loose and informal HRM practices was positively associated with being, and negatively associated with thinking, doing and harmony orientations. The theoretical and practical implications of these findings are discussed in detail

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates

Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (52–73) Tg N yr?1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4–3.1) Tg C from cell counts and to 89 (43–150) Tg C from nifH-based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 ± 9.2 Tg N yr?1, 18 ± 1.8 Tg C and 590 ± 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70%. It was recently established that the most commonly applied method used to measure N2 fixation has underestimated the true rates. As a result, one can expect that future rate measurements will shift the mean N2 fixation rate upward and may result in significantly higher estimates for the global N2 fixation. The evolving database can nevertheless be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models, keeping in mind that future rate measurements may rise in the future. The database is stored in PANGAEA (doi:10.1594/PANGAEA.774851)

Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

Peer reviewe

Photonic molecules and spectral engineering

This chapter reviews the fundamental optical properties and applications of pho-tonic molecules (PMs) - photonic structures formed by electromagnetic coupling of two or more optical microcavities (photonic atoms). Controllable interaction between light and matter in photonic atoms can be further modified and en-hanced by the manipulation of their mutual coupling. Mechanical and optical tunability of PMs not only adds new functionalities to microcavity-based optical components but also paves the way for their use as testbeds for the exploration of novel physical regimes in atomic physics and quantum optics. Theoretical studies carried on for over a decade yielded novel PM designs that make possible lowering thresholds of semiconductor microlasers, producing directional light emission, achieving optically-induced transparency, and enhancing sensitivity of microcavity-based bio-, stress- and rotation-sensors. Recent advances in material science and nano-fabrication techniques make possible the realization of optimally-tuned PMs for cavity quantum electrodynamic experiments, classical and quantum information processing, and sensing.Comment: A review book chapter: 29 pages, 19 figure

RANTES/CCL5 and risk for coronary events: Results from the MONICA/KORA Augsburg case-cohort, Athero-express and CARDIoGRAM studies

Background: The chemokine RANTES (regulated on activation, normal T-cell expressed and secreted)/CCL5 is involved in the pathogenesis of cardiovascular disease in mice, whereas less is known in humans. We hypothesised that its relevance for atherosclerosis should be reflected by associations between CCL5 gene variants, RANTES serum concentrations and protein levels in atherosclerotic plaques and risk for coronary events. Methods and Findings: We conducted a case-cohort study within the population-based MONICA/KORA Augsburg studies. Baseline RANTES serum levels were measured in 363 individuals with incident coronary events and 1,908 non-cases (mean follow-up: 10.2±

The impact of breastfeeding patterns on regional differences in infant mortality in Germany, 1910

This paper examines the impact of breastfeeding practices on the large regional differences in infant mortality in Germany around 1910. Breastfeeding is strongly negatively associated with infant mortality and remains so after controlling for public health measures and for demographic, economic, and social factors that also affect infant mortality. But it contributes much less to regional differences in infant mortality than do access to medical care, percentage illegitimate and marital fertility. Breastfeeding is less important than these other factors because it affects fewer causes of death and has a smaller impact on cause-specific infant mortality rates. L'auteur étudie l'impact des pratiques d'allaitement sur les grandes différences régionales de mortalité infantile observées en Allemagne aux alentours de 1910. Il existe une association fortement négative entre l'allaitement et la mortalité infantile, même quand on contrôle les facteurs démographiques, économiques, sociaux et de politique sanitaire, qui, eux aussi, affectent la mortalité infantile. Mais les différences régionales de mortalité infantile s'expliquent nettement moins par l'allaitement que par l'accessibilité des soins médicaux, le taux d'illégitimité des naissances et la fécondité légitime. L'allaitement est un facteur de moindre importance que ceux-ci parce qu'il n'a d'impact que sur un petit nombre de causes de décès, et un faible impact sur les taux de mortalité infantile par cause.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42730/1/10680_2005_Article_BF01796777.pd