1,122 research outputs found
Lubrication in cold rolling: Elasto-plasto-hydrodynamic lubrication
A model has been developed with respect to hydrodynamic lubrication in cold rolling. The basic model describes the configuration of a rigid, perfectly plastic sheet rolled by a rigid work roll. The governing equations have been solved throughout the complete contact area, i.e. the inlet, the work zone and the outlet zone. Multi-level techniques have been applied to solve these equations together with boundary conditions, resulting in an algorithm solving the problem in O(n) operations. This means that the distribution of the pressure and the traction force in the lubricant film, and the shape of this film, as well as the plastic deformation of the sheet, can be accurately calculated for a large number of nodal points on a minicomputer. Subsequently elastic deformation, work hardening and dynamic behaviour of the flow stress have been incorporated in the model. It will be shown that the influence of these effects on the film thickness or the pressure distribution is considerable
The Acute Compartment Syndrome of the Lower Leg: A Difficult Diagnosis?
Three patients, two adults and one child, developed an acute compartment syndrome of the lower leg. Due to delay in diagnosis, severe complications developed, resulting in two transfemoral amputations. In the youngest patient, the lower leg was able to be saved after extensive reconstructive surgery. In most cases, acute compartment syndrome of the lower leg is seen in combination with a fracture (40%), although other causes (minor trauma or vascular surgery) are also known. Moreover, patient history (pain out of proportion to the associated injury) and physical examination are central to the diagnosis. In some cases, however, a reliable diagnosis cannot be made clinically, as in the case of unconscious, intoxicated or intubated patients, as well as small children. Under these circumstances, intra-compartmental pressure measurement can be of great assistance. After confirmation of the diagnosis, immediate fasciotomy of all lower leg compartments should be performed. The eventual outcome of this syndrome is directly related to the time elapsed between diagnosis and definitive treatment. Although the diagnosis can be difficult, delays in treatment should be avoided at all costs. The acute compartment syndrome of the lower leg is a surgical emergency and should be dealt with immediately
Response to "To what extent, and how, might uncertainty be defined" by Norgon, Brown, and Mysiak
In a previous issue of Integrated Assessment (Vol. 4, No. 1), we proposed an uncertainty analysis framework, the aim of which was to provide a conceptual basis for the systematic treatment of uncertainty in model-based decision support activities, such as policy analysis, integrated assessment, and risk assessment. In the current issue, Norton, et al. present a critique and evaluation of the framework. This Disciplinary Perspective responds to their critique
The Structure of Screening in QED
The possibility of constructing charged particles in gauge theories has long
been the subject of debate. In the context of QED we have shown how to
construct operators which have a particle description. In this paper we further
support this programme by showing how the screening interactions arise between
these charges. Unexpectedly we see that there are two different gauge invariant
contributions with opposite signs. Their difference gives the expected result.Comment: 8 pages, LaTe
Exact Calculation of the Vortex-Antivortex Interaction Energy in the Anisotropic 3D XY-model
We have developed an exact method to calculate the vortex-antivortex
interaction energy in the anisotropic 3D-XY model. For this calculation, dual
transformation which is already known for the 2D XY-model was extended. We
found an explicit form of this interaction energy as a function of the
anisotropic ratio and the separation between the vortex and antivortex
located on the same layer. The form of interaction energy is at the
small limi t but is proportional to at the opposite limit. This form of
interaction energ y is consistent with the upper bound calculation using the
variational method by Cataudella and Minnhagen.Comment: REVTeX 12 pages, In print for publication in Phys. Rev.
Thermally Induced Diffusion and Restructuring of Iron Triade (Fe, Co, Ni) Nanoparticles Passivated by Several Layers of Gold
9 pags., 5 figs., 3 tabs.The temperature-induced structural changes of Fe−,
Co−, and Ni−Au core−shell nanoparticles with diameters around
5 nm are studied via atomically resolved transmission electron
microscopy. We observe structural transitions from local toward
global energy minima induced by elevated temperatures. The
experimental observations are accompanied by a computational
modeling of all core−shell particles with either centralized or
decentralized core positions. The embedded atom model is
employed and further supported by density functional theory
calculations. We provide a detailed comparison of vacancy formation
energies obtained for all materials involved in order to explain the
variations in the restructuring processes which we observe in
temperature-programmed TEM studies of the particles.This research has been supported by the Austrian Science
Fund (FWF) under Grant No. P 29893-N36, the FWF and the
Christian Doppler Research Association (CDG) under Grant
No. PIR8-N34, the Horizon 2020 research program of the
European Union under Grant No. 823717-ESTEEM3, and the
Spanish Agencia Estatal de Investigacion (AEI) and the Fondo ́
Europeo de Desarrollo Regional (FEDER, UE) under Grant
No. MAT2016-75354-P. The authors acknowledge the use of
HPC resources provided by the ZID of Graz University of
Technology and by the Vienna Scientific Cluster (VSC).
Further support by NAWI Graz is gratefully acknowledged.
The CESGA supercomputer center (Spain) is also acknowledged for having provided computational resources.Peer reviewe
Maintenance of Leukemia-Initiating Cells Is Regulated by the CDK Inhibitor Inca1
Functional differences between healthy progenitor and cancer initiating cells may provide unique opportunities for targeted therapy approaches. Hematopoietic stem cells are tightly controlled by a network of CDK inhibitors that govern proliferation and prevent stem cell exhaustion. Loss of Inca1 led to an increased number of short-term hematopoietic stem cells in older mice, but Inca1 seems largely dispensable for normal hematopoiesis. On the other hand, Inca1-deficiency enhanced cell cycling upon cytotoxic stress and accelerated bone marrow exhaustion. Moreover, AML1-ETO9a-induced proliferation was not sustained in Inca1-deficient cells in vivo. As a consequence, leukemia induction and leukemia maintenance were severely impaired in Inca1−/− bone marrow cells. The re-initiation of leukemia was also significantly inhibited in absence of Inca1−/− in MLL—AF9- and c-myc/BCL2-positive leukemia mouse models. These findings indicate distinct functional properties of Inca1 in normal hematopoietic cells compared to leukemia initiating cells. Such functional differences might be used to design specific therapy approaches in leukemia
Exchange coupling in CaMnO and LaMnO: configuration interaction and the coupling mechanism
The equilibrium structure and exchange constants of CaMnO and LaMnO
have been investigated using total energy unrestricted Hartree-Fock (UHF) and
localised orbital configuration interaction (CI) calculations on the bulk
compounds and MnO and MnO clusters. The
predicted structure and exchange constants for CaMnO are in reasonable
agreement with estimates based on its N\'eel temperature. A series of
calculations on LaMnO in the cubic perovskite structure shows that a
Hamiltonian with independent orbital ordering and exchange terms accounts for
the total energies of cubic LaMnO with various spin and orbital orderings.
Computed exchange constants depend on orbital ordering. UHF calculations tend
to underestimate exchange constants in LaMnO, but have the correct sign
when compared with values obtained by neutron scattering; exchange constants
obtained from CI calculations are in good agreement with neutron scattering
data provided the Madelung potential of the cluster is appropriate. Cluster CI
calculations reveal a strong dependence of exchange constants on Mn d e
orbital populations in both compounds. CI wave functions are analysed in order
to determine which exchange processes are important in exchange coupling in
CaMnO and LaMnO.Comment: 25 pages and 9 postscript figure
A High-Quality Genome-Scale Model for Rhodococcus opacus Metabolism
Rhodococcus opacus is a bacterium that has a high tolerance to aromatic compounds and can produce significant amounts of triacylglycerol (TAG). Here, we present iGR1773, the first genome-scale model (GSM) of R. opacus PD630 metabolism based on its genomic sequence and associated data. The model includes 1773 genes, 3025 reactions, and 1956 metabolites, was developed in a reproducible manner using CarveMe, and was evaluated through Metabolic Model tests (MEMOTE). We combine the model with two Constraint-Based Reconstruction and Analysis (COBRA) methods that use transcriptomics data to predict growth rates and fluxes: E-Flux2 and SPOT (Simplified Pearson Correlation with Transcriptomic data). Growth rates are best predicted by E-Flux2. Flux profiles are more accurately predicted by E-Flux2 than flux balance analysis (FBA) and parsimonious FBA (pFBA), when compared to 44 central carbon fluxes measured by 13C-Metabolic Flux Analysis (13C-MFA). Under glucose-fed conditions, E-Flux2 presents an R2 value of 0.54, while predictions based on pFBA had an inferior R2 of 0.28. We attribute this improved performance to the extra activity information provided by the transcriptomics data. For phenol-fed metabolism, in which the substrate first enters the TCA cycle, E-Flux2’s flux predictions display a high R2 of 0.96 while pFBA showed an R2 of 0.93. We also show that glucose metabolism and phenol metabolism function with similar relative ATP maintenance costs. These findings demonstrate that iGR1773 can help the metabolic engineering community predict aromatic substrate utilization patterns and perform computational strain design
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