Home About us Contact
|
Home About us Contact | ||
|
|
||
Cross-section
Kinds of Cross-section Terms modified by Cross-section Selected AbstractsLuck versus Skill in the Cross-Section of Mutual Fund ReturnsTHE JOURNAL OF FINANCE, Issue 5 2010EUGENE F. FAMA ABSTRACT The aggregate portfolio of actively managed U.S. equity mutual funds is close to the market portfolio, but the high costs of active management show up intact as lower returns to investors. Bootstrap simulations suggest that few funds produce benchmark-adjusted expected returns sufficient to cover their costs. If we add back the costs in fund expense ratios, there is evidence of inferior and superior performance (nonzero true ,) in the extreme tails of the cross-section of mutual fund , estimates. [source] Financial Constraints, Debt Capacity, and the Cross-section of Stock ReturnsTHE JOURNAL OF FINANCE, Issue 2 2009JAEHOON HAHN ABSTRACT Building on a model of corporate investment under collateral constraints, we develop and test a hypothesis on the differential effect of debt capacity on stock returns across financially constrained and unconstrained firms. Consistent with the hypothesis, we find that debt capacity is a significant determinant of stock returns only in the cross-section of financially constrained firms, after controlling for beta, size, book-to-market, leverage, and momentum. The findings suggest that cross-sectional differences in corporate investment behavior arising from financial constraints, predicted by theories of imperfect capital markets and supported by empirical evidence, are reflected in the stock returns of manufacturing firms. [source] Cash Flow, Consumption Risk, and the Cross-section of Stock ReturnsTHE JOURNAL OF FINANCE, Issue 2 2009ZHI DA ABSTRACT I link an asset's risk premium to two characteristics of its underlying cash flow: covariance and duration. Using empirically novel estimates of both cash flow characteristics based exclusively on accounting earnings and aggregate consumption data, I examine their dynamic interaction in a two-factor cash flow model and find that they are able to explain up to 82% of the cross-sectional variation in the average returns on size, book-to-market, and long-term reversal-sorted portfolios for the period 1964 to 2002. This finding highlights the importance of fundamental cash flow characteristics in determining the risk exposure of an asset. [source] Feeling Richer or Poorer than Others: A Cross-section and Panel Analysis of Subjective Economic Status in Indonesia,ASIAN ECONOMIC JOURNAL, Issue 2 2007Nattavudh Powdthavee O53; I3 This paper examines what makes us feel richer or poorer than others. It investigates cross-sectional and longitudinal determinants of individuals' subjective economic status in Indonesia. Using two waves of Indonesian Family Life Surveys, 1997 and 2000, I show that individuals' perceptions of where they are on the economic scale are more dependent on a number of socioeconomic characteristics, as well as their attitudes towards their future economic status, than their current spending capacities would suggest. I also find significant, albeit weaker, expenditure and income effects on individuals' subjective economic status once individual fixed effects are controlled for in the regression. [source] Angiotensin-converting enzyme inhibitors (ACEIs) and age-related maculopathy (ARM): cross-sectional findings from the Blue Mountains Eye StudyACTA OPHTHALMOLOGICA, Issue 3p1 2004Kathy H. C. Wu Abstract. Purpose:, To assess the relationship between the use of angiotensin-converting enzyme inhibitors (ACEIs) and prevalence of age-related maculopathy (ARM). Methods:, Eligible residents aged , 49 years were first examined in 1992,94 (Cross-section 1, n = 3654). Of these, 2335 were re-examined in 1997,99, together with an additional 1174 who became eligible after 1994 (Cross-section 2, n = 3509). Information regarding ACEI use was obtained and retinal photographs were graded using the Wisconsin ARM Grading System. Results:, In Cross-section 1, prevalence rates of late and early stage ARM were 1.3% and 4.3% among current ACEI users, and 2.0% and 4.8% among non-current users, respectively. In Cross-section 2, prevalence rates of late and early stage ARM were 2.3% and 11.3% among current ACEI users, and 1.3% and 9.3% among non-current users, respectively. After adjusting for age, sex and smoking, neither survey found any significant association between ACEI use and prevalence of either late or early ARM. Conclusions:, No significant cross-sectional associations were found between ACEI use and ARM prevalence in this population. [source] An automated pottery archival and reconstruction systemCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2003Martin Kampel Abstract Motivated by the current requirements of archaeologists, we are developing an automated archival system for archaeological classification and reconstruction of ceramics. Our system uses the profile of an archaeological fragment, which is the cross-section of the fragment in the direction of the rotational axis of symmetry, to classify and reconstruct it virtually. Ceramic fragments are recorded automatically by a 3D measurement system based on structured (coded) light. The input data for the estimation of the profile is a set of points produced by the acquisition system. By registering the front and the back views of the fragment the profile is computed and measurements like diameter, area percentage of the complete vessel, height and width are derived automatically. We demonstrate the method and give results on synthetic and real data. Copyright © 2003 John Wiley & Sons, Ltd. [source] Configuration Studies on the Heliotron Fusion Energy Reactor with Split-Type Helical CoilsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 6-7 2010N. Yanagi Abstract Configuration optimization is examined for the heliotron fusion energy reactor FFHR in order to find sufficient clearances between the ergodic region outside the nested magnetic surfaces and blankets at the inboard side of the torus. The standard configuration of FFHR, which is similar to that of LHD, has a relatively large major radius of the helical coils in order to satisfy this requirement. It has been found, as an alternative design, that equivalent clearances are obtained with a shorter major radius both by employing a lower helical pitch parameter and splitting the helical coils in the poloidal cross-section at the outboard side. Splitting the helical coils also provides another configuration that ensures magnetic well formation in the fairly large nested magnetic surfaces with outward shifted configurations. Optimization is being carried out for these configurations by adjusting the pitch modulation parameter to improve the particle confinement (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterisation of Zn:LiNbO3/Mg:LiNbO3 multilayer thin films grown by liquid phase epitaxyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2006H. J. Lee Abstract 1, 3 and 5 mol% ZnO doped LiNbO3 film and 2 mol% MgO doped LiNbO3 multilayer films were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with a Li2O-V2O5 system. We examined the optical transmission spectra of the Zn:LiNbO3 by Fourier Transform-Infrared Spectrophotometer (FT-IR). The crystallinity and the lattice mismatch between the Zn:LiNbO3 film and Mg:LiNbO3 film was confirmed by x-ray rocking curve (XRC) and observed the ZnO and MgO distribution in the cross-section of the multilayer thin films by electron probe micro analyzer (EPMA). Furthermore, the surface morphology of the films was observed using atomic force microscopy (AFM). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microstructure of a genuine Damascus sabreCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2005A. A. Levin Abstract The surface and cross-section of a genuine Damascus sword was characterised by means of wide-angle X-ray scattering techniques complemented by optical and transmisssion electron microscopy. Position-resolved X-ray phase analysis revealed that, unlike ferrite and martensite, the distribution of cementite is inhomogeneous in different spatial zones parallel to the cutting edge of the blade. For the first time a quantitative X-ray phase and texture analysis was made possible by averaging all spatial zones of the surface and the cross-section of the sword and applying the Rietveld method with code TOPAS. Differences concerning texture and structure characteristics of ferrite, martensite and cementite are discussed. More evidence for the structure of cementite nanowires is supplied. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Rapid Rise of Supermarkets?DEVELOPMENT POLICY REVIEW, Issue 2 2006W. Bruce Traill A series of articles, many of them published in this journal, have charted the rapid spread of supermarkets in developing and middle-income countries and forecast its continuation. In this article, the level of supermarket penetration (share of the retail food market) is modelled quantitatively on a cross-section of 42 countries for which data could be obtained, representing all stages of development. GDP per capita, income distribution, urbanisation, female labour force participation and openness to inward foreign investment are all significant explanators. Projections to 2015 suggest significant but not explosive further penetration; increased openness and GDP growth are the most significant factors. [source] Dating floodplain sediments using tree-ring response to burial,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2005Jonathan M. Friedman Abstract Floodplain sediments can be dated precisely based on the change in anatomy of tree rings upon burial. When a stem of tamarisk (Tamarix ramosissima) or sandbar willow (Salix exigua) is buried, subsequent annual rings in the buried section resemble the rings of roots: rings become narrower, vessels within the rings become larger, and transitions between rings become less distinct. We combined observations of these changes with tree-ring counts to determine the year of deposition of sedimentary beds exposed in a 150-m-long trench across the floodplain of the Rio Puerco, a rapidly filling arroyo in New Mexico. This method reliably dated most beds thicker than about 30 cm to within a year of deposition. Floodplain aggradation rates varied dramatically through time and space. Sediment deposition was mostly limited to brief overbank flows occurring every few years. The most rapid deposition occurred on channel-margin levees, which migrated laterally during channel narrowing. At the decadal timescale, the cross-section-average sediment deposition rate was steady, but there was a shift in the spatial pattern of deposition in the 1980s. From 1936 to 1986, sediment deposition occurred by channel narrowing, with little change in elevation of the thalweg. After 1986 sediment deposition occurred by vertical aggradation. From 1936 to 2000 about 27 per cent of the arroyo cross-section filled with sediment. The rate of filling from 1962 to 2000 was 0·8 vertical m/decade or 85 m2/decade. Published in 2005 by John Wiley & Sons, Ltd. [source] Coastal conglomerates around the Hadjer el Khamis inselbergs (western Chad, central Africa): new evidence for Lake Mega-Chad episodesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2003Mathieu Schuster Abstract This paper reports on a study dealing with the rhyolitic inselbergs of Hadjer el Khamis that formed palaeoislands during Lake Mega-Chad events. Field observations have shown that: (1) conglomeratic patches of immature to mature clasts are preserved at the feet of the Hadjer el Khamis inselbergs; (2) in cross-section, their pro,le reveals a well de,ned cliff,platform junction at a constant elevation (325 m). The monolithological clasts show all degrees of roundness, from angular cobbles to well rounded pebbles. This wide range of maturity suggests a coastal origin for these cobbles. The system was permanently fed with angular clasts, which were progressively worn by waves. Cobbles that were wave-worked for the longest time are the best rounded. The cliff,platform junction is the result of erosion by waves, which attacked and undercut the inselberg cliffs during Lake Mega-Chad events. Asymmetrical erosion pro,les moreover suggest a wind regime dominated by SW to NE oriented winds. These interpretations have two implications. The elevation of the cliff,platform junction is an indication of the highest water level of Lake Mega-Chad at 320,325 m, which is in agreement with other observations elsewhere in the basin. The SW to NE oriented winds show that monsoon-related winds were prevalent during Lake Mega-Chad events, suggesting the Inter-Tropical Convergence Zone was located higher in latitude than today. Copyright © 2003 John Wiley & Sons, Ltd. [source] ADV measurements of velocity distributions in a gravel-bed flumeEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2003Vito Ferro Abstract Velocity measurements carried out by an acoustic doppler velocimeter (ADV) in a rectangular laboratory ,ume having a gravel bed are presented. The velocity pro,les are measured in six verticals of the channel cross-section having an increasing distance (from 4 to 38·5 cm) from the ,ume wall. The experimental runs are carried out for ,ve different bed arrangements, characterized by different concentrations of coarser elements, and for the two conditions of small- and large-scale roughness. For both hydraulic conditions, the velocity measurements are ,rst used to test the applicability of the Dean pro,le and of the logarithmic pro,le corrected by a divergence function proposed in this paper. Then, for each value of the depth sediment ratio h/d84, the non-dimensional friction factor parameter is calculated by integration of the measured velocity distributions in the different verticals of the cross-section. Finally a semi-logarithmic ,ow resistance equation is empirically deduced. Copyright © 2003 John Wiley & Sons, Ltd. [source] A model of equilibrium bed topography for meander bends with erodible banksEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2002Stephen E. Darby Abstract Channel curvature produces secondary currents and a transverse sloping channel bed, along which the depth increases towards the outer bank. As a result deep pools tend to form adjacent to the outer bank, promoting bank collapse. The interaction of sediment grains with the primary and secondary flow and the transverse sloping bed also causes meanders to move different grain sizes in different proportions and directions, resulting in a consistent sorting pattern. Several models have been developed to describe this process, but they all have the potential to over-predict pool depth because they cannot account for the influence of erodible banks. In reality, bank collapse might lead to the development of a wider, shallower cross-section and any resulting flow depth discrepancy can bias associated predictions of flow, sediment transport, and grain-size sorting. While bed topography, sediment transport and grain sorting in bends will partly be controlled by the sedimentary characteristics of the bank materials, the magnitude of this effect has not previously been explored. This paper reports the development of a model of flow, sediment transport, grain-size sorting, and bed topography for river bends with erodible banks. The model is tested via intercomparison of predicted and observed bed topography in one low-energy (5·3 W m,2 specific stream power) and one high-energy (43·4 W m,2) study reach, namely the River South Esk in Scotland and Goodwin Creek in Mississippi, respectively. Model predictions of bed topography are found to be satisfactory, at least close to the apices of bends. Finally, the model is used in sensitivity analyses that provide insight into the influence of bank erodibility on equilibrium meander morphology and associated patterns of grain-size sorting. The sensitivity of meander response to bank cohesion is found to increase as a function of the available stream power within the two study bends. Copyright © 2002 John Wiley & Sons, Ltd. [source] Distorted Froude-scaled flume analysis of large woody debrisEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2001Nicholas P. Wallerstein Abstract This paper presents the results of a movable-boundary, distorted, Froude-scaled hydraulic model based on Abiaca Creek, a sand-bedded channel in northern Mississippi. The model was used to examine the geomorphic and hydraulic impact of simplified large woody debris (LWD) elements. The theory of physical scale models is discussed and the method used to construct the LWD test channel is developed. The channel model had bed and banks moulded from 0·8 mm sand, and flow conditions were just below the threshold of motion so that any sediment transport and channel adjustment were the result of the debris element. Dimensions and positions of LWD elements were determined using a debris jam classification model. Elements were attached to a dynamometer to measure element drag forces, and channel adjustment was determined through detailed topographic surveys. The fluid drag force on the elements decreased asymptotically over time as the channel boundary eroded around the elements due to locally increased boundary shear stress. Total time for geomorphic adjustment computed for the prototype channel at the Q2 discharge (discharge occurring once every two years on average) was as short as 45 hours. The size, depth and position of scour holes, bank erosion and bars created by flow acceleration past the elements were found to be related to element length and position within the channel cross-section. Morphologies created by each debris element in the model channel were comparable with similar jams observed in the prototype channel. Published in 2001 John Wiley & Sons, Ltd. [source] Cyclic tests on large-scale models of existing bridge piers with rectangular hollow cross-sectionEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 13 2003A. V. Pinto Abstract Cyclic tests on two large-scale models of existing bridge piers with rectangular hollow cross-section were performed in the ELSA laboratory. The prototype structure is an existing reinforced concrete highway bridge constructed in Austria in 1975. The piers presented several seismic deficiencies and consequently they showed poor hysteretic behaviour and limited deformation capacity as well as undesirable failure modes that do not comply with the requirements of modern codes for seismic-resistant structures. Experimental data are compared to numerical and empirical predictions. Copyright © 2003 John Wiley & Sons, Ltd. [source] Sample Splitting and Threshold EstimationECONOMETRICA, Issue 3 2000Bruce E. Hansen Threshold models have a wide variety of applications in economics. Direct applications include models of separating and multiple equilibria. Other applications include empirical sample splitting when the sample split is based on a continuously-distributed variable such as firm size. In addition, threshold models may be used as a parsimonious strategy for nonparametric function estimation. For example, the threshold autoregressive model (TAR) is popular in the nonlinear time series literature. Threshold models also emerge as special cases of more complex statistical frameworks, such as mixture models, switching models, Markov switching models, and smooth transition threshold models. It may be important to understand the statistical properties of threshold models as a preliminary step in the development of statistical tools to handle these more complicated structures. Despite the large number of potential applications, the statistical theory of threshold estimation is undeveloped. It is known that threshold estimates are super-consistent, but a distribution theory useful for testing and inference has yet to be provided. This paper develops a statistical theory for threshold estimation in the regression context. We allow for either cross-section or time series observations. Least squares estimation of the regression parameters is considered. An asymptotic distribution theory for the regression estimates (the threshold and the regression slopes) is developed. It is found that the distribution of the threshold estimate is nonstandard. A method to construct asymptotic confidence intervals is developed by inverting the likelihood ratio statistic. It is shown that this yields asymptotically conservative confidence regions. Monte Carlo simulations are presented to assess the accuracy of the asymptotic approximations. The empirical relevance of the theory is illustrated through an application to the multiple equilibria growth model of Durlauf and Johnson (1995). [source] Parental Separation and Children's Educational Attainment: A Siblings Analysis on Swedish Register DataECONOMICA, Issue 292 2006ANDERS BJÖRKLUND This paper analyses whether the commonly found negative relationship between parental separation in childhood and educational outcomes is causal or due mainly to selection. We use data on about 100,000 Swedish full biological siblings, born in 1948,63, and perform cross-section and sibling-difference estimations. Outcomes are measured as educational attainment in 1996. Our cross-section analysis shows the expected negative and significant relationship, while the relationship is not significant, though precisely estimated, in the sibling-difference analysis. This finding was robust to the sensitivity tests performed and is consistent with selection, rather than causation, being the explanation for the negative relationship. [source] Evaluation of poly(ethylene-co-vinyl acetate-co-carbon monoxide) and polydimethylsiloxane for equilibrium sampling of polar organic contaminants in waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Jörgen A Magnér Abstract Abstract-The aim of the present study was to develop a passive a bsorptive equilibrium sampler that would enable the determination of the concentrations of polar organic compound (POC) in water more efficiently than existing techniques. To this end, a novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated and the results were compared with an existing silicone-based passive absorptive equilibrium device. Seven compounds (imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon, and chlorpyrifos), a mixture of pharmaceuticals, and pesticides with a logarithmic octanol-water partition coefficient ranging from 0.2 to 4.77 were selected as model substances for the experiments. The results showed that six of the seven selected POCs reached distribution equilibrium within 4 d in the two materials tested. A linear relation with a regression coefficient of more than 0.8906 between the established logarithmic absorbent-water partition coefficient and the calculated logarithmic dissociation partition coefficient of the selected compounds in the two polymers was observed. The correlation between these two coefficients was within one order of magnitude for the compounds that reached equilibrium in the two polymers, which demonstrates that both materials are suitable for mimicking biological uptake of POCs. The PEVAC material showed an enhanced sorption for all selected compounds compared to the silicone material and up to five times higher enrichment for the most polar compound. Fluorescence analysis of the sampler cross-section, following the uptake of fluoranthene, and proof that the sorption was independent of surface area variations demonstrated that the PEVAC polymer possessed absorptive rather than adsorptive enrichment of organic compounds. [source] Long-term clopidogrel administration following severe coronary injury reduces proliferation and inflammation via inhibition of nuclear factor-kappaB and activator protein 1 activation in pigsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2009K. Pels ABSTRACT Background, The optimal duration of clopidogrel treatment following percutaneous coronary intervention (PCI) and the patient population that would benefit most are still unknown. In a porcine coronary injury model, we tested two different durations of clopidogrel treatment on severely or moderately injured arteries and examined the arterial response to injury. To understand the molecular mechanism, we also investigated the effects on transcription factors nuclear factor-kappaB (NF-,B) and activator protein 1 (AP-1). Materials and methods, In 24 cross-bred pigs, one coronary artery was only moderately injured by percutaneous transluminal coronary angioplasty (PTCA) and one coronary artery was severely injured by PTCA and subsequent beta-irradiation (Brachy group). Animals received 325 mg aspirin daily for 3 months and 75 mg clopidogrel daily for either 28 days [short-term (ST) clopidogrel group] or 3 months [long-term (LT) clopidogrel group]. Results, After 3 months, the number of proliferating cells per cross-section differed significantly between ST and LT in both injury groups (PTCAST 90·2 ± 10·3 vs. PTCALT 19·2 ± 4·7, P < 0·05; BrachyST 35·8 ± 8·4 vs. BrachyLT 7·5 ± 2·0, P < 0·05). Similar results were seen for inflammatory cells (CD3+ cells): PTCAST 23·5 ± 3·55 vs. PTCALT 4·67 ± 0·92, P < 0·05; BrachyST 83·17 ± 11·17 vs. BrachyLT 20 ± 4·82, P < 0·05). Long-term administration also reduced the activity of NF-,B and AP-1 by 62,64% and 42,58%, respectively. However, the effects of different durations of clopidogrel administration on artery dimensions were not statistically significant. Conclusions, Regarding inflammation and transcription factor activity at the PCI site, long-term clopidogrel administration is superior to short-term administration, especially in severely injured arteries. Transferring our results to the human situation, patients with more severely diseased arteries may benefit from a prolonged clopidogrel medication after PCI. [source] Inhibition of five lipoxygenase activating protein (FLAP) by MK-886 decreases atherosclerosis in apoE/LDLR-double knockout miceEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2006J. Jawien Abstract Background, Recent reports point to an important role of leukotrienes in atherogenesis. Leukotrienes are produced by 5-lipoxygenase co-operating with five lipoxygenase activating protein (FLAP). We hypothesized that MK-886, an inhibitor of FLAP, could attenuate the development of atherosclerosis in the atherogenic apolipoprotein E/low density lipoprotein receptor (apoE/LDLR) double knockout (DKO) mouse model. Materials and methods, Female apoE/LDLR-DKO mice at the age of 8 weeks were put on Western diet. The experimental group (n = 10) received the same diet as the control group (n = 10), but mixed with MK-886 (Merck, Rahway, NJ) at a dose of 4 µg per 100 mg of body-weight per day. At age 6 months the mice were sacrificed under anaesthesia. Results, Measured by the en face method, the percentage of area occupied by lesions in aortas in the control group was 25·15 ± 2·9%, whereas in the MK-886-treated group it was 11·16 ± 0·7% (P < 0·05). Lesion area measured by cross-section of aortic roots was 455 494 ± 29 564 µm2 in the control group versus 263 042 ± 20 736 µm2 in the MK-886-treated group (P < 0·05). The MK-886 did not change the plasma cholesterol lipoprotein profile as compared with the control mice. Finally, we show that MK-886 may increase plaque stability by decreasing the macrophage content as well as increasing the collagen and smooth-muscle cell content. Conclusions, Our results show for the first time that inhibition of FLAP by MK-886 reduces development of atherosclerosis in gene-targeted apoE/LDLR-DKO mice. [source] Mixed f-d Metallomesogens with an Extended Rigid CoreEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2005Koen Binnemans Abstract The liquid-crystalline behaviour of copper(II) and nickel(II) complexes of a mesogenic Schiff-base ligand derived from N,N' -disalicylidene-1,2-phenylenediamine (salophenH2) and of the corresponding trinuclear mixed copper(II)/lanthanum(III) and nickel(II)/lanthanum(III) complexes was investigated. High-temperature X-ray diffraction studies revealed that both the parent transition metal complexes and the mixed f-d complexes exhibit a hexagonal columnar phase (Colh) over an extended temperature range. Complex formation with lanthanum(III) nitrate resulted in an increase of the transition temperatures. The geometrical parameters (lattice parameters and column cross-section) of all the metal complexes are very similar, which indicates that the local organisation in the mesophase is the same despite their structural differences. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Biomorphic Silicon Carbide Coated with an Electrodeposition of Nanostructured Hydroxyapatite/Collagen as Biomimetic Bone Filler and Scaffold,ADVANCED ENGINEERING MATERIALS, Issue 8 2010M. Lelli Abstract The paper describes the method of preparation and chemical/physical characterization of a new biomaterial to be used as a bone substitute and bone-tissue engineering scaffold, which synergistically joins a porous bio-inspired morphology and the mechanical properties of biomorphic silicon carbide (BioSiC) with the surface bioactivity of a nanostructured hydroxyapatite/collagen biomimetic coating. FT-IR spectroscopy and XRD techniques are utilized to determine the chemical coating's composition. The morphology and size of the inorganic and protein components are investigated by TEM. The characteristic morphology of BioSiC channels and pores, which differ as a function of the transversal or longitudinal cross-section and with etching time, are investigated by SEM. Natural wood transformed into BioSiC acts as a cathode in an electrochemically assisted process that produces on its surface a biomimetic coating of hydroxyapatite nanocrystals and reconstituted type I collagen fibrils, producing an innovative apatite/collagen biomimetic porous bone filler and scaffold for tissue engineering. [source] A precise method for the impedance calculation of a power rail taking into account the skin effect and complex geometryEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2000Y. J. Wang The method of coupled inductance based on subdivision of conductors is employed in this paper for calculating the impedance of a power rail (also known as the conductor rail or third rail) considering the skin effect and complex geometry. The proposed method also allows the current distribution over the rail cross-section to be determined. A numerical technique that is able to economize on the number of subconductors required to achieve a prescribed level of accuracy, is also proposed to reduce computation time and matrix dimensions. [source] Eccentric cardiac hypertrophy was induced by long-term intermittent hypoxia in ratsEXPERIMENTAL PHYSIOLOGY, Issue 2 2007Li-Mien Chen It is unclear whether cardiac hypertrophy and hypertrophy-related pathways will be induced by long-term intermittent hypoxia. Thirty-six Sprague,Dawley rats were randomly assigned into three groups: normoxia, and long-term intermittent hypoxia (12% O2, 8 h per day) for 4 weeks (4WLTIH) or for 8 weeks (8WLTIH). Myocardial morphology, trophic factors and signalling pathways in the three groups were determined by heart weight index, histological analysis, Western blotting and reverse transcriptase-polymerase chain reaction from the excised left ventricle. The ratio of whole heart weight to body weight, the ratio of left ventricular weight to body weight, the gross vertical cross-section of the heart and myocardial morphological changes were increased in the 4WLTIH group and were further augmented in the 8WLTIH group. In the 4WLTIH group, tumour necrosis factor-,(TNF,), insulin-like growth factor (IGF)-II, phosphorylated p38 mitogen-activated protein kinase (P38), signal transducers and activators of transcription (STAT)-1 and STAT-3 were significantly increased in the cardiac tissues. However, in the 8WLTIH group, in addition to the above factors, interleukin-6, mitogen-activated protein kinase (MEK)5 and extracellular signal-regulated kinase (ERK)5 were significantly increased compared with the normoxia group. We conclude that cardiac hypertrophy associated with TNF, and IGF-II was induced by intermittent hypoxia. The longer duration of intermittent hypoxia further activated the eccentric hypertrophy-related pathway, as well as the interleukin 6-related MEK5,ERK5 and STAT-3 pathways, which could result in the development of cardiac dilatation and pathology. [source] Effect of Hypervelocity Impact on Microcellular Ceramic Foams from a Preceramic PolymerADVANCED ENGINEERING MATERIALS, Issue 11 2003P. Colombo A promising material for hypervelocity impact shields in spacecraft and satellites has been found in lightweight microcellular SiOC foams. The foam stops the projectile and the debris from the impacted bumper facesheet within a few millimeters (see Figure for a cross-section of the crater) at speeds up to 5.1 km,s,1. The impacted SiOC ceramic did not react with incoming debris, and no phase transformation or compositional change was observed. [source] Stress intensity factors for cracked triangular cross-section thin-walled tubesFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2004Y. J. XIE ABSTRACT For one kind of finite-boundary crack problems, the cracked equilateral triangular cross-section tube, an analytical and very simple method to determine the stress intensity factors has been proposed based on a new concept of crack surface widening energy release rate and the principle of virtual work. Different from the classical crack extension energy release rate, the crack surface widening energy release rate can be defined by the G*-integral theory and expressed by stress intensity factors. This energy release rate can also be defined easily by the elementary strength theory for slender structures and expressed by axial strains and loads. These two forms of crack surface widening energy release rate constitute the basis of a new analysis method for cracked tubes. From present discussions, a series of stress intensity factors are derived for cracked equilateral triangular cross-section tubes. Actually, the present method can also be applied to cracked polygonal tubes. [source] What Drives the S&P 500 Inclusion Effect?FINANCIAL MANAGEMENT, Issue 4 2006An Analytical Survey We present an analytical survey of the explanations,price pressure, downward-sloping demand curves, improved liquidity, improved operating performance, and increased investor awareness,for the increase in stock value associated with inclusion in the S&P 500 Index. We find that increased investor awareness is the primary factor behind the cross-section of abnormal announcement returns. We also find some evidence of temporary price pressure around the inclusion date. We find no evidence that long-run downward-sloping demand curves for stocks, anticipated improvements in operating performance, or increased liquidity are related to the cross-section of announcement or inclusion returns. [source] Structural fire design according to Eurocode 5,design rules and their backgroundFIRE AND MATERIALS, Issue 3 2005Jürgen KönigArticle first published online: 18 NOV 200 Abstract This paper gives a review of the design rules of EN 1995-1-2, the future common code of practice for the fire design of timber structures in the Member States of the EU and EFTA, and makes reference to relevant research background. Compared with the European pre-standard ENV 1995-1-2, the new EN 1995-1-2 has undergone considerable changes. Charring is dealt with in a more systematic way and different stages of protection and charring rates are applied. For the determination of cross-sectional strength and stiffness properties, two alternative rules are given, either by implicitly taking into account their reduction due to elevated temperature by reducing the residual cross-section by a zero-strength zone, or by calculating modification factors for strength and stiffness parameters. Design rules for charring and modification factors are also given for timber frame members of wall and floor assemblies with cavities filled with insulation. A modified components additive method has been included for the verification of the separating function. The design rules for connections have been systemized by introducing simple relationships between the load-bearing capacity (mechanical resistance) and time. The code provides for advanced calculation methods for thermal and structural analysis by giving thermal and thermo-mechanical properties for FE analyses. The code also gives some limited design rules for natural fire scenarios using parametric fire curves. Copyright © 2004 John Wiley & Sons, Ltd. [source] Time to ignition, heat release rate and fire endurance time of wood in cone calorimeter testFIRE AND MATERIALS, Issue 4 2001Toshiro HaradaArticle first published online: 15 MAR 200 The combustibility of wood specimens was tested by cone calorimeter. A total of nine wood species (four softwood and five hardwood) were used. The thicknesses of the specimens were 10, 20 and 40 mm. The heated surfaces were radial, tangential, and cross-sections of wood. The irradiance levels were 20, 25, 30, 40 and 50 kWm,2. The effects of wood species, density, specimen thickness, heated surface (radial, tangential or cross-section), and irradiance level on time to ignition, mass loss rate, heat release rate and fire endurance time were studied. Simple formulae were proposed to forecast those indices and their validity was examined. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||