35 research outputs found
NLO electroweak contributions to squark pair production at the LHC
We present the tree-level and next-to-leading order (NLO) electroweak (EW)
contributions to squark-squark production at the Large Hadron Collider (LHC)
within the framework of the Minimal Supersymmetric Standard Model (MSSM).Comment: To appear in the proceedings of 17th International Conference on
Supersymmetry and the Unification of Fundamental Interactions (SUSY09),
Boston, USA, 5-10 Jun 200
Top-squark pair production at the LHC: a complete analysis at next-to-leading order
We present a complete next-to-leading order study of top-squark pair
production at the LHC, including QCD and EW corrections. The calculation is
performed within the Minimal Supersymmetric Standard Model and numerical
results are presented for parameter regions compatible with the observed Higgs
boson. We employ the most recent parton distribution functions including QED
corrections and we find NLO EW corrections to the inclusive stop-pair
production cross section up to compared to the leading-order
prediction. Besides corrections to inclusive cross sections also important
kinematic distributions are investigated.Comment: 27 pages, 10 figures. Version published in JHEP. The numerical
discussion in Section 3 has been extended. References have been adde
Ökologische Sanitärlösungen in Afrika: Beitrag zu nachhaltiger Abfallentsor-gung und erhöhter Bodenfruchtbarkeit
While plant nutrient deficiencies are a major constraint to increasing crop yields in many rural parts of Sub-Saharan Africa, excess nutrients in organic wastes and wastewater cause environmental and hygienic problems in urban areas. We report on an ongoing research aimed at implementing principles of ecological sanitation on a university campus near Accra, Ghana. Alternative sanitation including dry urinals and separating toilets was installed in buildings. Pure urine, urine-water mix, greywater from baths and kitchens and faeces are treated and stored separately. Except for faeces, all materials are used to fertilise annual (urine) and perennial (urine-water, greywater) crops. Urine application significantly boosted maize and sorghum growth. Pathogens present in all fresh sanitary products, e.g. Escherichia coli, could be largely deactivated by six weeks of storage. A survey revealed no fundamental objections of farmers against the use of sanitary products. Scenario calculations suggest that recycling organic wastes and urine may contribute to alleviating nutrient deficiencies, particularly with regard to P and in densely settled areas. Future research should aim at developing hygienically safe, resource-efficient ways of urine application
Limited-Angle Tomography Reconstruction via Deep End-To-End Learning on Synthetic Data
Computed tomography (CT) has become an essential part of modern science and
medicine. A CT scanner consists of an X-ray source that is spun around an
object of interest. On the opposite end of the X-ray source, a detector
captures X-rays that are not absorbed by the object. The reconstruction of an
image is a linear inverse problem, which is usually solved by filtered back
projection. However, when the number of measurements is small, the
reconstruction problem is ill-posed. This is for example the case when the
X-ray source is not spun completely around the object, but rather irradiates
the object only from a limited angle. To tackle this problem, we present a deep
neural network that is trained on a large amount of carefully-crafted synthetic
data and can perform limited-angle tomography reconstruction even for only
30{\deg} or 40{\deg} sinograms. With our approach we won the first place in the
Helsinki Tomography Challenge 2022
Evolving temperature field in a fossil subduction channel during the transition from subduction to collision (Tauern Window, Eastern Alps)
We investigate the evolution of the three-dimensional thermal structure of a palaeo-subduction channel exposed in the Penninic units of the central Tauern Window (Eastern Alps). Structural and petrological observations reveal a sheath fold with an amplitude of some 20 km that formed under high-Pconditions (similar to 2 GPa). The fold is a composite structure that isoclinally folded the thrust of an ophiolitic nappe derived from Alpine Tethys Ocean onto a unit of the distal European continental margin, also affected by the high-Pconditions. This structural assemblage is preserved between two younger domes at either end of the Tauern Window. The domes deform isograds of theT-dominated Barrovian metamorphism that itself overprints the high-Pmetamorphism partly preserved in the sheath fold. Using Raman spectroscopy on carbonaceous material (RSCM), we are able to distinguish peak-temperature domains related to the original subduction metamorphism from domains associated with the later temperature-dominated (Barrovian) metamorphism. The distribution of RSCM temperatures in the Barrovian domain indicates a lateral and vertical decrease of peak temperature with increasing distance from the centres of the thermal domes. This represents a downward increase of palaeo-temperature, in line with previous studies. However, we observe the opposite palaeo-temperature trend in the lower limb of the sheath fold, namely an upward increase. We interpret this inverted palaeo-temperature domain as the relic of a subduction-related temperature field. Towards the central part of the sheath fold's upper limb, RSCM temperatures increase to a maximum of similar to 520 degrees C. Further upsection in the hangingwall of the sheath fold, palaeo-peak temperatures decrease to where they are indistinguishable from the peak temperatures of the overprinting Barrovian metamorphism. Peak-temperature contours of the subduction-related metamorphism are oriented roughly parallel to the folded nappe contacts and lithological layering. The contours close towards the northern, western and eastern parts of the fold, resulting in an eye-shaped, concentric pattern in cross-section. The temperature contour geometry therefore mimics the fold geometry itself, indicating that these contours were also folded in a sheath-like manner. We propose that this sheath-like pattern is the result of a two-stage process that reflects a change of the mode of nappe formation in the subduction zone from thrusting to fold nappe formation. First, thrusting of a hot oceanic nappe onto a colder continental nappe created an inverted peak-thermal gradient. Second, sheath folding of this composite nappe structure together with the previously established peak-temperature pattern during exhumation. This pattern was preserved because temperatures decreased during retrograde exhumation metamorphism and remained less than the subduction-related peak temperatures during the later Barrovian overprint. The fold ascended with diapir-like kinematics in the subduction channel
Hadronic production of bottom-squark pairs with electroweak contributions
We present the complete computation of the tree-level and the next-to-leading
order electroweak contributions to bottom-squark pair production at the LHC.
The computation is performed within the minimal supersymmetric extension of the
Standard Model. We discuss the numerical impact of these contributions in
several supersymmetric scenarios.Comment: 33 pages, v2: preprint numbers correcte
Hadronic production of squark-squark pairs: The electroweak contributions
We compute the electroweak (EW) contributions to squark--squark pair
production processes at the LHC within the framework of the Minimal
Supersymmetric Standard Model (MSSM). Both tree-level EW contributions, of
O(alpha_s alpha + alpha^2), and next-to-leading order (NLO) EW corrections, of
O(alpha_s^2 alpha), are calculated. Depending on the flavor and chirality of
the produced quarks, many interferences between EW-mediated and QCD-mediated
diagrams give non-zero contributions at tree-level and NLO. We discuss the
computational techniques and present an extensive numerical analysis for
inclusive squark--squark production as well as for subsets and single
processes. While the tree-level EW contributions to the integrated cross
sections can reach the 20% level, the NLO EW corrections typically lower the LO
prediction by a few percent.Comment: 36 pages, 18 figure
Imaging linear and circular polarization features in leaves with complete Mueller matrix polarimetry
Spectropolarimetry of intact plant leaves allows to probe the molecular architecture of vegetation photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological information. In addition to the molecular signals due to the photosynthetic machinery, the cell structure and its arrangement within a leaf can create and modify polarization signals. Using Mueller matrix polarimetry with rotating retarder modulation, we have visualized spatial variations in polarization in transmission around the chlorophyll a absorbance band from 650 nm to 710 nm. We show linear and circular polarization measurements of maple leaves and cultivated maize leaves and discuss the corresponding Mueller matrices and the Mueller matrix decompositions, which show distinct features in diattenuation, polarizance, retardance and depolarization. Importantly, while normal leaf tissue shows a typical split signal with both a negative and a positive peak in the induced fractional circular polarization and circular dichroism, the signals close to the veins only display a negative band. The results are similar to the negative band as reported earlier for single macrodomains. We discuss the possible role of the chloroplast orientation around the veins as a cause of this phenomenon. Systematic artefacts are ruled out as three independent measurements by different instruments gave similar results. These results provide better insight into circular polarization measurements on whole leaves and options for vegetation remote sensing using circular polarization
Interventionally implanted port catheter systems for hepatic arterial infusion of chemotherapy in patients with colorectal liver metastases: A phase II-study and historical comparison with the surgical approach
<p>Abstract</p> <p>Background</p> <p>The high complication rates of surgically implanted port catheter systems (SIPCS) represents a major drawback in the treatment of isolated liver neoplasms by hepatic arterial infusion (HAI) of chemotherapy. Interventionally implanted port catheter systems (IIPCS) have evolved into a promising alternative that enable initiation of HAI without laparatomy, but prospective data on this approach are still sparse. Aim of this study was to evaluate the most important technical endpoints associated with the use of IIPCS for the delivery of 5-fluorouracil-based HAI in patients with colorectal liver metastases in a phase 2-study, and to perform a non-randomised comparison with a historical group of patients in which HAI was administered via SIPCS.</p> <p>Methods</p> <p>41 patients with isolated liver metastases of colorectal cancer were enrolled into a phase II-study and provided with IIPCS between 2001 and 2004 (group A). The primary objective of the trial was defined as evaluation of device-related complications and port duration. Results were compared with those observed in a pre-defined historical collective of 40 patients treated with HAI via SIPCS at our institution between 1996 and 2000 (group B).</p> <p>Results</p> <p>Baseline characteristics were balanced between both groups, except for higher proportions of previous palliative pre-treatment and elevated serum alkaline phosphatase in patients of group A. Implantation of port catheters was successful in all patients of group A, whereas two primary failures were observed in group B. The frequency of device-related complications was similar between both groups, but the secondary failure rate was significantly higher with the use of surgical approach (17% vs. 50%, p < 0.01). Mean port duration was significantly longer in the interventional group (19 vs. 14 months, p = 0.01), with 77 vs. 50% of devices functioning at 12 months (p < 0.01). No unexpected complications were observed in both groups.</p> <p>Conclusion</p> <p>HAI via interventionally implanted port catheters can be safely provided to a collective of patients with colorectal liver metastases, including a relevant proportion of preatreated individuals. It appears to offer technical advantages over the surgical approach.</p
A Novel Diagnostic Target in the Hepatitis C Virus Genome
Christian Drosten and colleagues develop, validate, and make openly available a prototype hepatitis C virus assay based on the conserved 3' X-tail element, with potential for clinical use in developing countries