900 research outputs found
SILLi 1.0: A 1D Numerical Tool Quantifying the Thermal Effects of Sill Intrusions
Igneous intrusions in sedimentary basins may have a profound effect on the thermal structure and physical properties of the hosting sedimentary rocks. These include mechanical effects such as deformation and uplift of sedimentary layers, generation of overpressure, mineral reactions and porosity evolution, and fracturing and vent formation following devolatilization reactions and the generation of CO2 and CH4. The gas generation and subsequent migration and venting may have contributed to several of the past climatic changes such as the end-Permian event and the Paleocene-Eocene Thermal Maximum. Additionally, the generation and expulsion of hydrocarbons and cracking of pre-existing oil reservoirs around a hot magmatic intrusion is of significant interest to the energy industry. In this paper, we present a user-friendly 1D FEM based tool, SILLi, which calculates the thermal effects of sill intrusions on the enclosing sedimentary stratigraphy. The model is accompanied by three case studies of sills emplaced in two different sedimentary basins, the Karoo Basin in South Africa and the Vøring Basin offshore Norway. Input data for the model is the present-day well log or sedimentary column with an Excel input file and includes rock parameters such as thermal conductivity, total organic carbon (TOC) content, porosity, and latent heats. The model accounts for sedimentation and burial based on a rate calculated by the sedimentary layer thickness and age. Erosion of the sedimentary column is also included to account for realistic basin evolution. Multiple sills can be emplaced within the system with varying ages. The emplacement of a sill occurs instantaneously. The model can be applied to volcanic sedimentary basins occurring globally. The model output includes the thermal evolution of the sedimentary column through time, and the changes that take place following sill emplacement such as TOC changes, thermal maturity, and the amount of organic and carbonate-derived CO2. The TOC and vitrinite results can be readily benchmarked within the tool to present-day values measured within the sedimentary column. This allows the user to determine the conditions required to obtain results that match observables and leads to a better understanding of metamorphic processes in sedimentary basins
Irradiation specifically sensitises solid tumour cell lines to TRAIL mediated apoptosis
BACKGROUND: TRAIL (tumor necrosis factor related apoptosis inducing ligand) is an apoptosis inducing ligand with high specificity for malignant cell systems. Combined treatment modalities using TRAIL and cytotoxic drugs revealed highly additive effects in different tumour cell lines. Little is known about the efficacy and underlying mechanistic effects of a combined therapy using TRAIL and ionising radiation in solid tumour cell systems. Additionally, little is known about the effect of TRAIL combined with radiation on normal tissues. METHODS: Tumour cell systems derived from breast- (MDA MB231), lung--(NCI H460) colorectal--(Colo 205, HCT-15) and head and neck cancer (FaDu, SCC-4) were treated with a combination of TRAIL and irradiation using two different time schedules. Normal tissue cultures from breast, prostate, renal and bronchial epithelia, small muscle cells, endothelial cells, hepatocytes and fibroblasts were tested accordingly. Apoptosis was determined by fluorescence microscopy and western blot determination of PARP processing. Upregulation of death receptors was quantified by flow cytometry. RESULTS: The combined treatment of TRAIL with irradiation strongly increased apoptosis induction in all treated tumour cell lines compared to treatment with TRAIL or irradiation alone. The synergistic effect was most prominent after sequential application of TRAIL after irradiation. Upregulation of TRAIL receptor DR5 after irradiation was observed in four of six tumour cell lines but did not correlate to tumour cell sensitisation to TRAIL. TRAIL did not show toxicity in normal tissue cell systems. In addition, pre-irradiation did not sensitise all nine tested human normal tissue cell cultures to TRAIL. CONCLUSIONS: Based on the in vitro data, TRAIL represents a very promising candidate for combination with radiotherapy. Sequential application of ionising radiation followed by TRAIL is associated with an synergistic induction of cell death in a large panel of solid tumour cell lines. However, TRAIL receptor upregulation may not be the sole mechanism by which sensitation to TRAIL after irradiation is induced
Successful Therapy for a Patient With an Infected Ascending Aortic Graft and Sternal Osteomyelitis Without Graft Removal
Objective: Following open-heart surgery, sternal osteomyelitis or infection of the graft may be a serious complication with high mortality rates. The recommended treatment of an infected graft is its explantation. Because of the poor performance status of the patient, this may not always be an option. We report a successful treatment concept without removal of the infected graft. Methods: The infected ascending aortic graft and the remaining sternum of a critically ill 60-year-old man were covered with a bilateral pectoralis muscle flap. Results: Postoperatively, the laboratory test values normalized and the patient was discharged 1 month after the intervention. One year after surgery, the patient was in good condition and the examination showed no signs of infection. Conclusion: The thus demonstrated treatment concept with insertion of well-vascularized tissues in combination with a specific antibiotic regime in our hands proved to be an additional option for the successful management of life-threatening infections of a sternal osteomyelitis in combination of an infected aortic graft
Finding shuffle words that represent optimal scheduling of shared memory access
This is an Author's Accepted Manuscript of an article published in International Journal of Computer Mathematics [© Taylor & Francis], available online at: http://www.tandfonline.com/doi/abs/10.1080/00207160.2012.698007In the present paper, we introduce and study the problem of computing, for any given nite
set of words, a shu e word with a minimum so-called scope coincidence degree. The scope
coincidence degree is the maximum number of di erent symbols that parenthesise any position
in the shu e word. This problem is motivated by an application of a new automaton model
and can be regarded as the problem of scheduling shared memory accesses of some parallel
processes in a way that minimises the number of memory cells required. We investigate the
complexity of this problem and show that it can be solved in polynomial time
No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR
Timing of high-count rate sources with the NuSTAR Small Explorer Mission
requires specialized analysis techniques. NuSTAR was primarily designed for
spectroscopic observations of sources with relatively low count-rates rather
than for timing analysis of bright objects. The instrumental dead time per
event is relatively long (~2.5 msec), and varies by a few percent
event-to-event. The most obvious effect is a distortion of the white noise
level in the power density spectrum (PDS) that cannot be modeled easily with
the standard techniques due to the variable nature of the dead time. In this
paper, we show that it is possible to exploit the presence of two completely
independent focal planes and use the cross power density spectrum to obtain a
good proxy of the white noise-subtracted PDS. Thereafter, one can use a Monte
Carlo approach to estimate the remaining effects of dead time, namely a
frequency-dependent modulation of the variance and a frequency-independent drop
of the sensitivity to variability. In this way, most of the standard timing
analysis can be performed, albeit with a sacrifice in signal to noise relative
to what would be achieved using more standard techniques. We apply this
technique to NuSTAR observations of the black hole binaries GX 339-4, Cyg X-1
and GRS 1915+105.Comment: 13 pages, 8 figures, submitted to Ap
Interference and interaction effects in multi-level quantum dots
Using renormalization group techniques, we study spectral and transport
properties of a spinless interacting quantum dot consisting of two levels
coupled to metallic reservoirs. For strong Coulomb repulsion and an applied
Aharonov-Bohm phase , we find a large direct tunnel splitting
between the levels of
the order of the level broadening . As a consequence we discover a
many-body resonance in the spectral density that can be measured via the
absorption power. Furthermore, for , we show that the system can be
tuned into an effective Anderson model with spin-dependent tunneling.Comment: 5 pages, 4 figures included, typos correcte
Isotope Effects on Delayed Annihilation Time Spectra of Antiprotonic Helium Atoms in Low-Temperature Gas
The delayed annihilation time spectra (DATS) of antiprotonic helium atoms have been studied in isotopically pure low temperature ^3He and ^4He gas at various densities. The DATS taken at 5.8~K and 400~mbar are very similar in shape except for i) a small difference in the time scale and ii) the presence of a distinct fast decay component in the case of ^3He. The ratio of overall trapping times (mean lifetimes against annihilation), R = T_{\mathrm{trap}}(\mbox{^{4}He})/T_{\mathrm{trap}}(\mbox{^{3}He}), has been determined to be 1.144 \pm 0.009, which is in good agreement with a theoretical estimate yielding R = [(M^*(\mbox{\overline{\mathrm{p}}}\mbox{^{4}He})/ M^*(\mbox{\overline{ \mathrm{p}}}\mbox{^{3}He})]^2=1.14, where M^* denotes the reduced mass of the \mbox{\overline{\mathrm{p}}}\mbox{He^{++}}\ system. The presence of a short-lived component with a lifetime of (0.154\pm 0.007)\ \mbox{\mus} in the case of \mbox{^{3}He}\ suggests that the \mbox{\overline{\mathrm{p}}}\mbox{^{3}He^{+}}\ atom has a state of intermediate lifetime on the border between a metastable zone and an Auger-dominated short-lived zone. The fraction of antiprotons trapped in metastable states at 5.8~K and 400~mbar is lower by 22.2(4)\% for \mbox{^{3}He}\ than for \mbox{^{4}He}. All the data can be fitted fai
New Symmetries in Crystals and Handed Structures
For over a century, the structure of materials has been described by a
combination of rotations, rotation-inversions and translational symmetries. By
recognizing the reversal of static structural rotations between clockwise and
counterclockwise directions as a distinct symmetry operation, here we show that
there are many more structural symmetries than are currently recognized in
right- or left-handed handed helices, spirals, and in antidistorted structures
composed equally of rotations of both handedness. For example, though a helix
or spiral cannot possess conventional mirror or inversion symmetries, they can
possess them in combination with the rotation reversal symmetry. Similarly, we
show that many antidistorted perovskites possess twice the number of symmetry
elements as conventionally identified. These new symmetries predict new forms
for "roto" properties that relate to static rotations, such as rotoelectricity,
piezorotation, and rotomagnetism. They also enable symmetry-based search for
new phenomena, such as multiferroicity involving a coupling of spins, electric
polarization and static rotations. This work is relevant to structure-property
relationships in all material structures with static rotations such as
minerals, polymers, proteins, and engineered structures.Comment: 15 Pages, 4 figures, 3 Tables; Fig. 2b has error
Two-Channel Kondo Physics from Tunnelling Impurities with Triangular Symmetry
Tunnelling impurities in metals have been known for some time to have the
potential for exhibiting Kondo-like physics. However previous models based on
an impurity hopping between two equivalent positions have run into trouble due
to the existence of relevant operators that drive the system away from the
non-Fermi-liquid Kondo fixed point. In the case of an impurity hopping among
positions with higher symmetry, such as triangular symmetry, it is shown here
that the non-Fermi-liquid behavior at low temperatures can be generic. Using
various bosonization techniques, the fixed point is shown to be {\em stable}.
However, unlike the conventional two-channel Kondo (2CK) model, it has {\em
four} leading irrelevant operators, implying that while the form of the
singular temperature dependence of physical quantities is similar to the 2CK
model, there will not be simple universal amplitude ratios. The phase diagram
of this system is analyzed and a critical manifold is found to separate the
non-Fermi-liquid from a conventional Fermi liquid fixed point. Generalization
to higher symmetries, such as cubic, and the possibility of physical
realizations with dynamic Jahn-Teller impurities is discussed.Comment: 20 pages, 4 figures, RevTex format, submitted to Phys. Rev.
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