Wiederherstellung einer homogenen Information Security Policy aus proprietär gewachsenen Berechtigungsverwaltungen in einer großen öffentlichen Institution

Zugriffskontrolle ist ein wesentliches Sicherheitsmerkmal moderner Datenverarbeitung. Aktuelle EDV-Systeme bieten spezifische Möglichkeiten, Berechtigungen festzulegen. Die Entscheidung, welcher Benutzerkreis über welche Berechtigungen in einem System verfügt, kommt aus organisatorischer, beziehungsweise fachlicher Ebene und wird in Form von Sicherheitsrichtlinien festgehalten. Das Umsetzen und Administrieren obliegt in Folge technischem Fachpersonal. Aufgrund dieser physischen Trennung und oftmals fehlendem Fachwissen ist es den für die Berechtigungsfestlegung verantwortlichen Mitarbeitern schwer bis unmöglich, aktuell vergebene Berechtigungen zu kontrollieren. Ein einfacher Export und Weitergabe der Berechtigungsinformationen scheitert an den proprietären Zugriffskontrollmechanismen ebenso wie an den bei manchen Systemen gar nicht vorgesehenen Exportfunktionen. Nach einer umfassenden und strukturierten Beschreibung aller erforderlichen theoretischen Grundlagen werden im Zuge dieser Arbeit unterschiedliche Berechtigungsstrukturen am Beispiel einiger Geschäftsapplikationen eines Großunternehmens analysiert und Gemeinsamkeiten gefunden. Diese bilden ein Schema einer vereinheitlichten Darstellung aller in den Systemen vergebenen Berechtigungen. Somit können nach entsprechender Aufarbeitung der einzelnen Berechtigungsdaten diese in einer einheitlichen Form in einer zentralen Datenbank abgelegt werden und für weitere Analysen und Visualisierungen den für die Richtigkeit der Berechtigungen verantwortlichen Personen zur Verfügung gestellt werden.Access Control is one of the crucial security features in modern computing. Todays information systems provide specific ways to define access rights. The decision, what right is granted to which user of a system is met on organizational or functional level and is described by information security policies. The implementation and administration shall be done by technical experts. Due to this physical separation and often lack of know-how it is hardly possible for the security staff in charge to know the actual rights. Since every system implements its own proprietary export or no export at all, comparison of access right information is very difficult. This also becomes an obstacle when rights are to be consolidated. After a broad, structured description of relevant theoretical concepts this work will analyse and compare access control structures on hand of business applications of a large enterprise. This will lead to the composition of a schema of an uniform representation of the assigned rights. Using this schema a database is constructed where the security staff in charge is able to access and analyse the aggregated information. This work provides a broad theoretical base in respect of access control

Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

International audienceThe evolution of ozone and 13 volatile organic compounds (VOCs) in the boundary layer of Mexico City was investigated during 2000?2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of ozone and meteorological parameters up to 1000 m above ground during part of the diurnal cycle (02:00?18:00 h). VOCs samples were collected up to 200 m by pumping air to canisters with a Teflon tube attached to the tether line. Overall, features of these profiles were found to be consistent with a simple picture of nighttime trapping of ozone in an upper residual layer and of VOCs in a shallow unstable layer above the ground. After sunrise an ozone balance is determined by photochemical production, entrainment from the upper residual layer and destruction by titration with NO, delaying the ground-level ozone rise by 2 h. The subsequent evolution of the conductive boundary layer and vertical distribution of pollutants are discussed in terms of the energy balance, the presence of turbulence and the atmospheric stability

Toward the next generation of air quality monitoring: Persistent organic pollutants

AbstractPersistent Organic Pollutants (POPs) are global pollutants that can migrate over long distances and bioaccumulate through food webs, posing health risks to wildlife and humans. Multilateral environmental agreements, such as the Stockholm Convention on POPs, were enacted to identify POPs and establish the conditions to control their release, production and use. A Global Monitoring Plan was initiated under the Stockholm Convention calling for POP monitoring in air as a core medium; however long temporal trends (>10 years) of atmospheric POPs are only available at a few selected sites. Spatial coverage of air monitoring for POPs has recently significantly improved with the introduction and advancement of passive air samplers. Here, we review the status of air monitoring and modeling activities and note major uncertainties in data comparability, deficiencies of air monitoring and modeling in urban and alpine areas, and lack of emission inventories for most POPs. A vision for an internationally-integrated strategic monitoring plan is proposed which could provide consistent and comparable monitoring data for POPs supported and supplemented by global and regional transport models. Key recommendations include developing expertise in all aspects of air monitoring to ensure data comparability and consistency; partnering with existing air quality and meteorological networks to leverage synergies; facilitating data sharing with international data archives; and expanding spatial coverage with passive air samplers. Enhancing research on the stability of particle-bound chemicals is needed to assess exposure and deposition in urban areas, and to elucidate long-range transport. Conducting targeted measurement campaigns in specific source areas would enhance regional models which can be extrapolated to similar regions to estimate emissions. Ultimately, reverse-modeling combined with air measurements can be used to derive “emission” as an indicator to assess environmental performance with respect to POPs on the country, region, or global level

Largeâ eddy simulation of biogenic VOC chemistry during the DISCOVERâ AQ 2011 campaign

Biogenic volatile organic compounds (BVOCs) are oxidized quickly in the atmosphere to form oxygenated VOC (OVOC) and play crucial roles in the formation of ozone and secondary organic aerosols. We use the National Center for Atmospheric Research’s largeâ eddy simulation model and Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality 2011 flight data to understand the role of boundary layer turbulence on the atmospheric chemistry of key BVOC species and their oxidation products. We simulate three distinct convective environments during the campaign, representing fair weather conditions (case 1: 1 July), a convective event dominated by southwesterly flow (case 2: 11 July), and a polluted event with high temperature and convection (case 3: 29 July). Isoprene segregation is greatest in the lower boundary layer under warm and convective conditions, reaching up to a 10% reduction in the isopreneâ OH reaction rate. Under warm and convective conditions, the BVOC lifetimes lengthen due to increased isoprene emission, elevated initial chemical concentrations, and OH competition. Although turbulenceâ driven segregation has less influence on the OVOC species, convection mixes more OVOC into the upper atmospheric boundary layer (ABL) and increases the total OH reactivity. Production and loss rates of ozone above 2â km in all the three cases indicate in situ ozone formation in addition to vertical convective transport of ozone from the surface and aloft, consistent with the increased contribution of OH reactivity from OVOC. Together, these results show that total OH reactivity in the ABL increases under warmer and stronger convective conditions due to enhanced isoprene emission and the OVOC contribution to ozone formation.Key PointsLES and DISCOVERâ AQ flight data are compared to understand the role of turbulence on BVOC chemistryTurbulenceâ induced segregation is less important for OVOC than isoprene, but OVOC compensates for isoprene rate reductionsConvection mixes more OVOC into the upper ABL and increases total OH reactivityPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133566/1/jgrd53113_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133566/2/jgrd53113-sup-0001-SI-S01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133566/3/jgrd53113.pd

Global multimedia source-receptor relationships for persistent organic pollutants during use and after phase-out

AbstractChemicals that are persistent in the atmosphere can be transported long distances and across international boundaries. Therefore, information about the fraction of local versus imported air pollution is required to formulate regulations aimed at controlling pollutant levels. The objective of this work is to illustrate the capabilities of a dynamic global–scale multimedia model to calculate source–receptor relationships for persistent organic pollutants that cycle between air, water, soil and vegetation in the global environment. As exemplary case studies, we present model calculations of time–evolving source–receptor relationships for PCB28, PCB153, α–HCH and β–HCH over the duration of their usage, phase–out and a post–ban period. Our analysis is geographically explicit, and elucidates the role of primary versus secondary sources in controlling the levels of air pollution. Our case studies consider source–receptor relationships between the four regions defined by the Convention on Long–range Transboundary Air Pollution Task Force on Hemispheric Transport of Air Pollution, as well as the Arctic as a remote receptor region. We find source–receptor relationships that are highly variable over time, and between different regions and chemicals. Air pollution by PCBs in North America and Europe is consistently dominated by local emissions, whereas in East– and South–Asia extra–regional sources are sometimes major contributors. Emissions of α–HCH peak at different times in the four regions, which leads to a phase of high self–pollution in each region, and periods when pollution enters mainly from outside. Compared to α–HCH, air pollution with the less volatile and more persistent β–HCH is more strongly determined by secondary emissions near source areas throughout its use history. PCB concentrations in Arctic air are dominated by emissions transported from North America and Europe from 1930 to 2080, whereas for HCHs each of the source regions contributes a high share at some point between 1950 and 2050