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151.
Jutta Ellermann Wen Ling Mikko J. Nissi Elizabeth Arendt Cathy S. Carlson Michael Garwood Shalom Michaeli Silvia Mangia 《Magnetic resonance imaging》2013
In the present work we introduced two MRI rotating frame relaxation methods, namely adiabatic T1ρ and Relaxation Along a Fictitious Field (RAFF), along with an inversion-prepared Magnetization Transfer (MT) protocol for assessment of articular cartilage. Given the inherent sensitivity of rotating frame relaxation methods to slow molecular motions that are relevant in cartilage, we hypothesized that adiabatic T1ρ and RAFF would have higher sensitivity to articular cartilage degradation as compared to laboratory frame T2 and MT. To test this hypothesis, a proteoglycan depletion model was used. Relaxation time measurements were performed at 0 and 48 h in 10 bovine patellar specimens, 5 of which were treated with trypsin and 5 untreated controls were stored under identical conditions in isotonic saline for 48 h. Relaxation times measured at 48 h were longer than those measured at 0 h in both groups. The changes in T2 and MT relaxation times after 48 h were approximately 3 times larger in the trypsin treated specimens as compared to the untreated group, whereas increases of adiabatic T1ρ and RAFF were 4 to 5 fold larger. Overall, these findings demonstrate a higher sensitivity of adiabatic T1ρ and RAFF to the trypsin-induced changes in bovine patellar cartilage as compared to the commonly used T2 and MT. Since adiabatic T1ρ and RAFF are advantageous for human applications as compared to standard continuous-wave T1ρ methods, adiabatic T1ρ and RAFF are promising tools for assessing cartilage degradation in clinical settings. 相似文献
152.
Juha Kinnunen Riikka Korte Tuomo Kuusi Mikko Parviainen 《Mathematische Annalen》2013,355(4):1349-1381
We extend the theory of the thermal capacity for the heat equation to nonlinear parabolic equations of the $p$ -Laplacian type. We study definitions and properties of the nonlinear parabolic capacity and show that the capacity of a compact set can be represented via a capacitary potential. As an application, we show that polar sets of superparabolic functions are of zero capacity. The main technical tools used include estimates for equations with measure data and obstacle problems. 相似文献
153.
Leskinen MV Yip KT Valkonen A Pihko PM 《Journal of the American Chemical Society》2012,134(13):5750-5753
The dehydrogenative β'-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β'-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented. 相似文献
154.
Mikko Vepslinen 《Nuclear Physics A》2009,820(1-4):279c
We study quarkonium in hot QCD, emphasizing its nature as a short-lived transient with an exponentially decaying wave function. The heavy quark mass allows for a nonrelativistic expansion around the two-quark threshold, and the static potential is then seen to contain a temperature-dependent imaginary part, which leads to an unstable quark-antiquark state. We solve the corresponding Schrödinger equation and estimate the spectral functions in different channels. In particular, through careful evaluation we find a peak also in the scalar channel, although it is strongly suppressed with respect to the vector channel peak. We also plot the dilepton production rate, which shows a peak-like structure even at temperatures so high that the peak in the spectral function has disappeared. 相似文献
155.
Carleman estimates and inverse problems for Dirac operators 总被引:1,自引:0,他引:1
We consider limiting Carleman weights for Dirac operators and prove corresponding Carleman estimates. In particular, we show
that limiting Carleman weights for the Laplacian also serve as limiting weights for Dirac operators. As an application we
consider the inverse problem of recovering a Lipschitz continuous magnetic field and electric potential from boundary measurements
for the Pauli Dirac operator.
M. Salo is supported by the Academy of Finland. L. Tzou is supported by the Doctoral Post-Graduate Scholarship from the Natural
Science and Engineering Research Council of Canada. This article was written while L. Tzou was visiting the University of
Helsinki and TKK, whose hospitality is gratefully acknowledged. The authors would like to thank András Vasy and Lauri Ylinen
for useful comments. 相似文献
156.
We report on a novel extension of the recently introduced phase-field crystal (PFC) method [Elder, Phys. Rev. Lett. 88, 245701 (2002)10.1103/PhysRevLett.88.245701], which incorporates elastic interactions as well as crystal plasticity and diffusive dynamics. In our model, elastic interactions are mediated through wave modes that propagate on time scales many orders of magnitude slower than atomic vibrations but still much faster than diffusive time scales. This allows us to preserve the quintessential advantage of the PFC model: the ability to simulate atomic-scale interactions and dynamics on time scales many orders of magnitude longer than characteristic vibrational time scales. We demonstrate the two different modes of propagation in our model and show that simulations of grain growth and elastoplastic deformation are consistent with the microstructural properties of nanocrystals. 相似文献
157.
Dias CL Ala-Nissila T Karttunen M Vattulainen I Grant M 《Physical review letters》2008,100(11):118101
We elucidate the mechanism of cold denaturation through constant-pressure simulations for a model of hydrophobic molecules in an explicit solvent. We find that the temperature dependence of the hydrophobic effect induces, facilitates, and is the driving force for cold denaturation. The physical mechanism underlying this phenomenon is identified as the destabilization of hydrophobic contact in favor of solvent-separated configurations, the same mechanism seen in pressure-induced denaturation. A phenomenological explanation proposed for the mechanism is suggested as being responsible for cold denaturation in real proteins. 相似文献
158.
In this paper a brief overview of the electro-thermal simulation based on the method of simultaneous iteration is given, through the example of the SISSI (Simulator for Integrated Structures by Simultaneous Iteration) package. The modular approach used for the layout-based electro-thermal netlist generation is described. This approach allows an easy implementation of package model libraries. The capabilities of SISSI are introduced by simulation examples where in most cases the results are compared to measurement results. 相似文献
159.
160.
Maciej Wolborski Mietek Bakowski Armando Ortiz Viljami Pore Adolf Schner Mikko Ritala Markku Leskel Anders Halln 《Microelectronics Reliability》2006,46(5-6):743-755
Al2O3 films were deposited using atomic layer deposition (ALD) and ultrasonic spray pyrolysis (USP) methods on p- and n-type Si substrates, n-type 4H–SiC substrates and 4H–SiC diodes for passivation studies. UV exposure in N2 atmosphere and 5% HF treatment were used as two separate surface preparation procedures prior to Al2O3 deposition. The films deposited with USP technique contain a large amount of fixed negative charge and are vulnerable to water incorporation into the material. The Al2O3 film prepared by ALD method shows much better uniformity and less negative charge. Decrease of the leakage current in the 4H–SiC diodes is observed after Al2O3 passivation using both methods. 相似文献