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Critical Regions (critical + regions)

Distribution by Scientific Domains

Medical Sciences	22%

Selected Abstracts

Probabilities of activation of seismic faults in critical regions of the Aegean area

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2004
C. B. Papazachos
SUMMARY Properties of the accelerating seismic crustal deformation pattern and of the intermediate-term seismic quiescence pattern have been combined to identify faults in the Aegean area (34°N,43°N, 19°E,30°E) that have a considerable probability of generating strong earthquakes (M, 6.4) during the next 5-yr period. Eight groups of such faults have been identified, and the probability of each fault being activated during this time period has been estimated. Three of these groups are located in southern Greece (Hellenic Arc), two in central Greece (East Central Greece, Ionian Islands), two in northwestern Turkey and one in the area of the borders of Albania, Greece and the Former Yugoslav Republic of Macedonia. The importance of these results for intermediate-term seismic hazard assessment is discussed. [source]

Explicit robust model predictive control using recursive closed-loop prediction

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2006
Danlei Chu
Abstract In this paper, we develop an algorithm to compute robust MPC explicit solutions for constrained MIMO systems with internal uncertainties and external disturbances. Our approach is based on a recursive closed-loop prediction strategy to realize a finite horizon robust MPC regulator, which has the feature that only one-step state prediction is sufficient to realize robust MPC with an arbitrary prediction horizon. The paper defines a set of recursive sub-optimization problems as multiple-parametric sub-quadratic programming (mp-SQP), and shows that the optimal solution to the mp-SQP problem is piecewise affine functions of states, associated with piece objectives and state critical regions. Asymptotic closed-loop stability can be guaranteed by a terminal weighting and a terminal feedback gain; also by introducing two tuning variables, the algorithm is capable of adjusting the trade-off between system performance and robustness. The state admissible set, which is not easily derived from physical vision, is constructed by two methods: a piecewise linear norm of signals, and polyhedral Voronoi sets. Finally, two simulation examples demonstrate that the algorithm is efficient, feasible and flexible, and can be applied to both slow and fast industrial MIMO systems. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Elemental distributions in femoral bone of rat under osteoporosis preventive treatments

JOURNAL OF MICROSCOPY, Issue 3 2006
M. D. YNSA
Summary One of the abnormalities of bone architecture is osteoporosis as occurring in post-menopausal women. Especially long bones, such as femur, become more fragile and more prone to fracture. The efficiency of several osteoporosis preventative treatments based on oestrogen and progestin in bone structure and mineral recovery was studied using ovariectomized Wistar rats as an osteoporosis experimental model. Diagonal cross-sections of the proximal epiphysis of femoral bones were analysed using nuclear microscopy techniques in order to map and determine the concentration profiles of P, Ca, S, Fe and Zn from the epiphysis to diaphysis and across the cortical and trabecular bone structures. In control animals (not ovariectomized), the S and Zn contents significantly characterized differences between cortical and trabecular bone structures, whereas P and Ca showed increased gradients from the epiphyseal region to the diaphysis. After ovariectomy the differences observed were differential according to the type of hormonal supplementation. A significant decrease in P and Ca contents and depletion of minor and trace minerals, such as S, Fe and Zn, were found for both cortical and trabecular bone structures after ovariectomy relative to controls. Bone mineral contents were reversed to control levels by synthetic oestrogen supplementation, and combined oestrogen and progesterone treatment. Recovery was more evident in the femoral epiphysis and neck than in the diaphysis. The use of oestrogen alone did not lead to bone recovery after ovariectomy. Alterations in bone mineral composition observed for animals receiving synthetic oestrogen and combined oestrogen and progesterone supplement might reflect beneficial structural changes in critical regions of long bones, mostly affected in post-menopausal osteoporosis. [source]

OLS ESTIMATION AND THE t TEST REVISITED IN RANK-SIZE RULE REGRESSION,

JOURNAL OF REGIONAL SCIENCE, Issue 4 2008
Yoshihiko Nishiyama
ABSTRACT The rank-size rule and Zipf's law for city sizes have been traditionally examined by means of OLS estimation and the t test. This paper studies the accurate and approximate properties of the OLS estimator and obtains the distribution of the t statistic under the assumption of Zipf's law (i.e., Pareto distribution). Indeed, we show that the t statistic explodes asymptotically even under the null, indicating that a mechanical application of the t test yields a serious type I error. To overcome this problem, critical regions of the t test are constructed to test the Zipf's law. Using these corrected critical regions, we can conclude that our results are in favor of the Zipf's law for many more countries than in the previous researches such as Rosen and Resnick (1980) or Soo (2005). By using the same database as that used in Soo (2005), we demonstrate that the Zipf law is rejected for only one of 24 countries under our test whereas it is rejected for 23 of 24 countries under the usual t test. We also propose a more efficient estimation procedure and provide empirical applications of the theory for some countries. [source]

Testing modified Newtonian dynamic with Local Group spiral galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007
Edvige Corbelli
ABSTRACT The rotation curves and the relative mass distributions of the two nearby Local Group spiral galaxies, M31 and M33, show discrepancies with modified Newtonian dynamic (MOND) predictions. In M33, the discrepancy lies in the kinematics of the outermost regions. It can be alleviated by adopting tilted ring models compatible with the 21-cm datacube but different from the one that best fits the data. In M31, MOND fails to fit the falling part of the rotation curve at intermediate radii, before the curve flattens out in the outermost regions. Newtonian dynamics in a framework of a stellar disc embedded in a dark halo can explain the complex rotation curve profiles of these two galaxies, while MOND has some difficulties. However, given the present uncertainties in the kinematics of these nearby galaxies, we cannot address the success or failure of MOND theory in a definite way. More sensitive and extended observations around the critical regions, suggested by MOND fits discussed in this paper, may lead to a definite conclusion. [source]

Absence of neuronal nitric oxide synthase (nNOS) as a pathological marker for the diagnosis of Becker muscular dystrophy with rod domain deletions

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2004
S. Torelli
Immunohistochemistry using antibodies to dystrophin is the pathological basis for the diagnosis of Duchenne and Becker muscular dystrophy (DMD and BMD). While the sarcolemma of DMD muscle is negative, BMD muscle generally shows variable labelling because of the translation of a partially functional dystrophin that is localized to the sarcolemma. In rare cases, however, this labelling is equivocal and similar to that observed in controls making diagnosis difficult. We report here that in such instances immunolabelling with antibodies to the neuronal form of nitric oxide synthase (nNOS) can be useful in suspecting a dystrophinopathy with a mutation in the ,hot-spot' rod domain and help to direct molecular analysis. nNOS localizes to the sarcolemma of mature muscle fibres via several components of the dystrophin-associated protein complex (DAPC) including dystrophin but sarcolemmal nNOS is lost when dystrophin levels are very low or absent because of deletions in critical regions of the rod domain. We report three cases who presented with only mild or no muscle weakness but had elevated serum creatine kinase activity and dystrophin immunolabelling indistinguishable from normal, making a pathological diagnosis difficult. All three cases had a complete absence of sarcolemmal nNOS and were subsequently found to have an in-frame deletion in the common rod domain exons (in these cases 48, 45,51, 47,53) compatible with a BMD. In addition, we observed that nNOS appears to be developmentally regulated with the antibody used and was often absent from the sarcolemma of immature fibres. These findings demonstrate the value of including antibodies to nNOS in routine immunohistochemical studies and that absence of nNOS can be a more sensitive marker than up-regulation of utrophin for diagnosis of BMD. Immaturity of fibres, however, needs to be taken into account, especially in neonates. [source]

Some Simple Tests for Spatial Effects Around Putative Sources of Health Risk

BIOMETRICAL JOURNAL, Issue 4 2007
Andrew B. Lawson
Abstract The need for tests dealing with different features of small area health data is less important with the increase in computation speed of computers and the access to MCMC methods. However there are many situations where exploratory testing could be useful and where MCMC methods are not readily useable or available. In this paper, a number of simple tests are derived for the logistic model for case events. This model assumes that a control disease is available and that the events have a binary label relating to case or control state. The tests are derived from likelihood considerations and Monte Carlo critical regions are examined. A simulated evaluation of the tests is presented in terms of Monte Carlo power. A data example is considered. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Global phase behavior of imidazolium ionic liquids and compressed 1,1,1,2-tetrafluoroethane (R-134a)

AICHE JOURNAL, Issue 2 2009
Wei Ren
Abstract Novel processes involving ionic liquids with refrigerant gases have recently been developed. Here, the complete global phase behavior has been measured for the refrigerant gas, 1,1,1,2-tetrafluoroethane (R-134a) and 1- n -alkyl-3-methyl-imidazolium ionic liquids with the anions hexafluorophosphate [PF6], tetrafluoroborate [BF4] and bis(trifluoromethylsulfonyl)imide [Tf2N] from ,0°C to 105°C and to 33 MPa. All of the systems studied were Type V from the classification scheme of Scott-van Konynenburg with regions of vapor-liquid equilibrium, miscible/critical regions, vapor-liquid-liquid equilibrium, and upper and lower critical endpoints (UCEP and LCEP). The effect of the alkyl chain length has been investigated, for ethyl-([EMIm]), n -butyl-([BMIm]), and n -hexyl-([HMIm]). With increasing chain length, the temperature of the lower critical end points increases and pressure at the mixture critical points decrease. With a common cation, the temperature of the LCEP increased and the mixture critical point pressures decreased in the order of [BF4], [PF6], and [Tf2N]. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source]