Supersymmetry at the Tevatron ?

These lectures contain an introduction to the search for supersymmetry at hadron colliders. The Tevatron is one of high-energy physics most sophisticated tools. The high center-of-mass energy of its proton-antiproton collisions makes it an ideal place to search for physics beyond the Standard Model, such as supersymmetry. Two experiments, CDF and D\O, completed a long data taking period in summer of 1995, yielding over $100 p b^{-1}$ of proton-- antiproton interactions. The data recorded by the experiments are still being analysed. The lectures outline the strategies in the search for supersymmetry at the Tevatron and examine the major analyses in detail. Results obtained by the two experiments are included where available.Comment: 40 pages, 13 figure

Search for Higgs and New Phenomena at Colliders

The present status of searches for the Higgs boson(s) and new phenomena is reviewed. The focus is on analyses and results from the current runs of the HERA and Tevatron experiments. The LEP experiments have released their final combined MSSM Higgs results for this conference. Also included are results from sensitivity studies of the LHC experiments and lepton flavour violating searches from the B factories, KEKB and PEP-II.Comment: XXII International Symposium on Lepton-Photon Interactions at High Energy (11 pages, 16 figures, 2 tables

The effects of arbuscular mycorrhizal fungi (AMF) and Rhizophagus irregularis on soil microorganisms assessed by metatranscriptomics and metaproteomics

Arbuscular mycorrhizal fungi (AMF) form symbioses with approximately 80% of plant species and potentially benefit their hosts (e.g. nutrient acquisition) and the soil environment (e.g. soil aggregation). AMF also affect soil microbiota and soil multifunctionality. We manipulated AMF presence (via inoculation of non-sterile soil with Rhizophagus irregularis and using a hyphal compartment design) and used RNA-seq and metaproteomics to assess AMF roles in soil. The results indicated that AMF drove an active soil microbial community expressing transcripts and proteins related to nine metabolic functions, including the metabolism of C and N. We suggest two possible mechanisms: 1) the AMF hyphae produce exudates that select a beneficial community, or, 2) the hyphae compete with other soil microbes for available nutrients and consequently induce the community to mineralize nutrients from soil organic matter. We also identified candidate proteins that are potentially related to soil aggregation, such as Lpt and HSP60. Our results bridge microbial ecology and ecosystem functioning. We show that the AMF hyphosphere contains an active community related to soil respiration and nutrient cycling, thus potentially improving nutrient mineralization from soil organic matter and nutrient supply to the plants

Formation of Nitrous Acid: Parameterisation and comparison with observations

Nitrous acid formation in the troposphere is described in the light of the most recent advances of knowledge on NOx chemistry on ground and aerosol surfaces. It is suggested to follow the stoichiometry of the reaction 2 NO; + H20 -> HNO2 + HNO3 on all ambient surfaces except those of carbonaceous particles. The influences of ambient humidity on aerosol (water uptake) and ground surface area (surface to area indices) and on water availability for surface reactions are considered. It is concluded that the state of the reacting H20 molecule, chemisorbed to the surface or other, is determining: The ldnetics of the process obeys first order in N02 concentration and eidier pseudo-zeroth order (for low surface coverage with I-12_, using to: - 0.1 - 1 * 10-6 for the various surface types) or first order in water vapour concentration (for water molecules available on the surface in multilayer adsorption, using km =- 1.36 * 10-20 cm4 moles1 s as determined in a laboratory experiment on a humid vessel wall). A reaction mechanism is proposed. The scheme differentiates between 4 ground surface and 4 aerosol surfaces types. Predicted and observed nitrous acid formation rates from two urban sites are compared. For this purpose, observed rates and their' error bars were derived with particular care. Despite large uncertainties for both predicted and observed values, the agreement is good for both low and high humidities (mean predicted/observed = 138 % for 18 nights in Mainz, 1986/87, and 132 % for 9 nights in Milano, 1994)

Fractionation and current time trends of PCB congeners: evolvement of distributions 1950–2010 studied using a global atmosphere-ocean general circulation model

PCBs are ubiquitous environmental pollutants expected to decline in abiotic environmental media in response to decreasing primary emissions since the 1970s. A coupled atmosphere-ocean general circulation model with embedded dynamic sub-models for atmospheric aerosols and the marine biogeochemistry and air-surface exchange processes with soils, vegetation and the cryosphere is used to study the transport and fate of four PCB congeners covering a range of 3–7 chlorine atoms. <br><br> The change of the geographic distribution of the PCB mixture reflects the sources and sinks' evolvement over time. Globally, secondary emissions (re-volatilisation from surfaces) are on the long term increasingly gaining importance over primary emissions. Secondary emissions are most important for the congeners with 5–6 chlorine atoms. Correspondingly, the levels of these congeners are predicted to decrease slowest. Changes in congener mixture composition (fractionation) are characterized both geographically and temporally. In high latitudes enrichment of the lighter, less persistent congeners and more delayed decreasing levels in response to decreasing emissions are found. The delivery of the contaminants to high latitudes is predicted to be more efficient than previously suggested. The results suggest furthermore that the effectiveness of emission control measures may significantly vary among substances. The trends of decline of organic contaminant levels in the abiotic environmental media do not only vary with latitude (slow in high latitudes), but do also show longitudinal gradients

Greenhouse effect of NOx

Through various processes the nitrogen oxides (NO,) interact: with trace gases in the troposphere and stratosphere which do absorb in the spectral range relevant to the greenhouse effect (infrared wavelengths). The net effect is an enhancement of the greenhouse effect. The catalytic role of NO, in the production of tropospheric ozone provides the most prominent contribution. The global waming potential is estimated as GWP (NOx) = 30 - 33 and 7 - 10 for the respective time horizons of 20 and 100 years, and is thereby comparable to chat of methane. NO, emissions in rural areas of anthropogenically influenced regions, or those in the vicinity of the tropopause caused by air traffic, cause the greenhouse effectivity to be substantially more intense. We estimate an additional 5 - 23 % for Germany's contribution to the anthropogenic greenhouse effect as a result of the indirect greenhouse effects stemming from NO,. Furthermore, a small and still inaccurately defined amount of the deposited NO, which has primarily been converted into nitrates is again released from the soil into the atmosphere in the form of the long-lived greenhouse gas nitrous oxide (N2O). Thus, anchropogenically induced NOx emissions contribute to enhanced greenhouse effect and to stratospheric ozone depletion in the time scale of more than a century

Comparative Study on Concept Construction for Violence, Intelligence and Religion in Early Adolescence in the Parisian Suburbs

Based on association tasks, we focused our research on the process of concept construction and on the nature of the semantic structure network of three important concepts in the lives of young adolescents in the Parisian suburbs: violence, religion and intelligence. In this exploratory study, we were interested in identifying similarities and differences in the organization of these social concepts between adolescents with French parents and adolescents with immigrant parents. Despite the fact that these children share common “eco-cultural” experiences, we supposed that the different cultural guidelines in the family settings might influence the construction and the semantic organization of the concepts. Subjects were all born in France (N=228), and they share the same social environment and low socioeconomic status. Analyses of representational fields and of semantic networks were conducted and evidence for some similarities as well as for major differences between the two groups in concept construction and in semantic organization was present. Our findings showed a more homogeneous organization in children with immigrant parents; meanwhile French children’s structures of concepts are more heterogeneous. Major differences can also be observed at the semantic level. The findings are discussed in respect to the concept formation literature and the eco-cultural approach of human development

Nitrous acid and nitrite in the atmosphere

Nitrous acid is a minor trace gas, yet has an important influence on OH concentrations in the troposphere. Gas phase concentrations in both rural and urban air are larger than predicted from laboratory studies of homogeneous or heterogeneous chemistry. A better understanding of the mechanisms which produce nitrous acid in the atmosphere will lead to improved model of nitrogen oxide and OH chemistry, particularly in polluted air