Experimental results on searches beyond the Standard Model

Recent results for direct searches for physics beyond the Standard Model are reviewed. The results include Tevatron II data up to 1.2 fb-1 and HERA results up to 350 pb-1. Searches for Supersymmetry, for compositeness and for large extra dimensions are presented. The excess of events with an isolated lepton and high missing transverse momentum at HERA is discussed.Comment: 10 pages, 15 figures, Plenary talk at the ICHEP06 conference, Moscow, July 26-August 2, 200

A longer XMM-Newton look at I Zwicky 1: Distinct modes of X-ray spectral variability

The short-term spectral variability of the narrow-line Seyfert 1 galaxy I Zwicky 1 (I Zw 1) as observed in an 85 ks XMM-Newton observation is discussed in detail. I Zw 1 shows distinct modes of variability prior to and after a flux dip in the broad-band light curve. Before the dip the variability can be described as arising from changes in shape and normalisation of the spectral components. Only changes in normalisation are manifested after the dip. The change in the mode of behaviour occurs on dynamically short timescales in I Zw 1. The data suggest that the accretion-disc corona in I Zw 1 could have two components that are co-existing. The first, a uniform, physically diffuse plasma responsible for the "typical'' long-term (e.g. years) behaviour; and a second compact, centrally located component causing the rapid flux and spectral changes. This compact component could be the base of a short or aborted jet as sometimes proposed for radio-quiet active galaxies. Modelling of the average and time-resolved rms spectra demonstrate that a blurred Compton-reflection model can describe the spectral variability if we allow for pivoting of the continuum component prior to the dip.Comment: 8 pages, 9 figures. Accepted by MNRA

Alien Registration- Gallo, Felicia N. (Millinocket, Penobscot County)

https://digitalmaine.com/alien_docs/7196/thumbnail.jp

An intense soft-excess and evidence for light bending in the luminous narrow-line quasar PHL 1092

The narrow-line quasar PHL 1092 was observed by XMM-Newton at two epochs separated by nearly thirty months. Timing analyses confirm the extreme variability observed during previous X-ray missions. A measurement of the radiative efficiency is in excess of what is expected from a Schwarzschild black hole. In addition to the rapid X-ray variability, the short UV light curves (< 4 hours) obtained with the Optical Monitor may also show fluctuations, albeit at much lower amplitude than the X-rays. In general, the extreme variability is impressive considering that the broad-band (0.4-10 keV rest-frame) luminosity of the source is ~10^45 erg/s. During at least one of the observations, the X-ray and UV light curves show common trends, although given the short duration of the OM observations, and low significance of the UV light curves it is difficult to comment on the importance of this possible correlation. Interestingly, the high-energy photons (> 2 keV) do not appear highly variable. The X-ray spectrum resembles that of many narrow-line Seyfert 1 type galaxies: an intense soft-excess modelled with a multi-colour disc blackbody, a power-law component, and an absorption line at ~1.4 keV. The ~1.4 keV feature is curious given that it was not detected in previous observations, and its presence could be related to the strength of the soft-excess. Of further interest is curvature in the spectrum above ~2 keV which can be described by a strong reflection component. The strong reflection component, lack of high-energy temporal variability, and extreme radiative efficiency measurements can be understood if we consider gravitational light bending effects close to a maximally rotating black hole.Comment: To appear in MNRAS. Submitted March 01, 2004. 9 page

Structuring expert input for a knowledge-based approach to watershed condition assessment for the Northwest Forest Plan, USA

Assessments of watershed condition for aquatic and riparian species often have to rely on expert opinion because of the complexity of establishing statistical relationships among the many factors involved. Such expert-based assessments can be difficult to document and apply consistently over time and space. We describe and reflect on the process of developing a computer-based decision support application from expert judgments for assessing aquatic and riparian conditions over the 100,000 km2 managed by the US federal government under the Northwest Forest Plan. The decision support system helped structure and document the assessment process and provided consistency and transparency to the evaluation methodology. However, many decisions and trade-offs were required in the expert engagement and model-building processes. Knowledge elicitation in an interactive group had a number of benefits over nominal group or Delphi processes, but efficient knowledge capture required considerable planning and expertise in the subject matter and modeling process. Communicating model results for validation was problematic and only effectively accomplished via in-person workshops. The choice to use different expert groups for each biophysical province provided more opportunities for participation and promoted greater ownership in the assessment, but it also led to increased variation among the resulting model structures. We propose three possible approaches for better managing the consistency of assessment models when multiple expert groups are involved

XMM-Newton observation of the ULIRG NGC 6240: The physical nature of the complex Fe K line emission

We report on an XMM-Newton observation of the ultraluminous infrared galaxy NGC 6240. The 0.3-10 keV spectrum can be successfully modelled with: (i) three collisionally ionized plasma components with temperatures of about 0.7, 1.4, and 5.5 keV; (ii) a highly absorbed direct power-law component; and (iii) a neutral Fe K_alpha and K_beta line. We detect a significant neutral column density gradient which is correlated with the temperature of the three plasma components. Combining the XMM-Newton spectral model with the high spatial resolution Chandra image we find that the temperatures and the column densities increase towards the center. With high significance, the Fe K line complex is resolved into three distinct narrow lines: (i) the neutral Fe K_alpha line at 6.4 keV; (ii) an ionized line at about 6.7 keV; and (iii) a higher ionized line at 7.0 keV (a blend of the Fe XXVI and the Fe K_beta line). While the neutral Fe K line is most probably due to reflection from optically thick material, the Fe XXV and Fe XXVI emission arises from the highest temperature ionized plasma component. We have compared the plasma parameters of the ultraluminous infrared galaxy NGC 6240 with those found in the local starburst galaxy NGC 253. We find a striking similarity in the plasma temperatures and column density gradients, suggesting a similar underlying physical process at work in both galaxies.Comment: 8 pages including 9 figures. Accepted for publication in A&

CXCR4-targeted and MMP-responsive iron oxide nanoparticles for enhanced magnetic resonance imaging

MRI offers high spatial resolution with excellent tissue penetration but it has limited sensitivity and the commonly administered contrast agents lack specificity. In this study, two sets of iron oxide nanoparticles (IONPs) were synthesized that were designed to selectively undergo copper-free click conjugation upon sensing of matrix metalloproteinase (MMP) enzymes, thereby leading to a self-assembled superparamagnetic nanocluster network with T2 signal enhancement properties. For this purpose, IONPs with bioorthogonal azide and alkyne surfaces masked by polyethylene glycol (PEG) layers tethered to CXCR4-targeted peptide ligands were synthesized and characterized. The IONPs were tested in vitro and T2 signal enhancements of around 160 % were measured when the IONPs were incubated with cells expressing MMP2/9 and CXCR4. Simultaneous systemic administration of the bioorthogonal IONPs in tumor-bearing mice demonstrated the signal-enhancing ability of these ‘smart’ self-assembling nanomaterials