Panel Cointegration Testing in the Presence of Common Factors

Panel unit root and no-cointegration tests that rely on cross-sectional independence of the panel unit experience severe size distortions when this assumption is violated, as has e.g. been shown by Banerjee, Marcellino and Osbat (2004, 2005) via Monte Carlo simulations. Several studies have recently addressed this issue for panel unit root test using a common factor structure to model the cross-sectional dependence, but not much work has been done yet for panel no-cointegration tests. This paper proposes a model for panel no-cointegration using an unobserved common factor structure, following the work on Bai and Ng (2004) for panel unit roots. The model enables us to distinguish two important cases: (i) the case when the non-stationarity in the data is driven by a reduced number of common stochastic trends, and (ii) the case where we have common and idiosyncratic stochastic trends present in the data. We study the asymptotic behavior of some existing, residual-based panel no-cointegration, as suggested by Kao (1999) and Pedroni (1999, 2004). Under the DGP used, the test statistics are no longer asymptotically normal, and convergence occurs at rate T rather than sqrt(N)T as for independent panels. We then examine the properties of residual-based tests for no-cointegration applied to defactored data from which the common factors and individual components have been extracted.econometrics;

Introduction of a pyramid guiding process for general musculoskeletal physical rehabilitation

Successful instruction of a complicated subject as Physical Rehabilitation demands organization. To understand principles and processes of such a field demands a hierarchy of steps to achieve the intended outcome. This paper is intended to be an introduction to a proposed pyramid scheme of general physical rehabilitation principles. The purpose of the pyramid scheme is to allow for a greater understanding for the student and patient. As the respected Food Guide Pyramid accomplishes, the student will further appreciate and apply supported physical rehabilitation principles and the patient will understand that there is a progressive method to their functional healing process

The Role of Surface Characteristics in the Initial Adhesion of Human Bone-Derived Cells on Ceramics

The tissue/biomaterial interactions of three biomaterials of potential use in bone implants were studied in vitro. The mechanism of cell adherence to various ceramic substrata has been investigated by measurement of short term (90 minutes) cell attachment and spreading rate. We have determined the effect of two serum glycoproteins, fibronectin and vitronectin, on the adhesion of human bone derived cells (HBD-cells) cultured on three different types of ceramics {alumina (Al2O3), hydroxyapatite (HAP) and yttria-doped tetragonal zirconia polycrystal (Y-TZP)} . The attachment of HBD-cells to alumina and hydroxyapatite was approximately 60% of that to Y-TZP. Furthermore, the requirement for serum adhesive glycoproteins vitronectin and fibronectin, for HBD-cell attachment to Al2O3, HAP and Y-TZP reveals a dependence upon serum vitronectin for the initial attachment of HBD-cells. There was no difference in the mechanism of initial adhesion between bioactive hydroxyapatite, as compared to the bioinert ceramics, alumina and Y-TZP, so the mechanism of the initial attachment of HBD-cells appears not to be dependent on the ceramic composition. The effect of surface roughness of alumina in the order of 8.3-70.7 nm on the adhesion of HBD-cells was also investigated. The Al2O3 disks with a root mean square surface roughness (roughness assessment: Ra) value of 8.3 nm had significantly fewer cells attached than those with an Ra of 70.7 nm

Array tomography: Characterizing FAC-sorted populations of zebrafish immune cells by their 3D ultrastructure

For 3D reconstructions of whole immune cells from zebrafish, isolated from adult animals by FAC-sorting we employed array tomography on hundreds of serial sections deposited on silicon wafers. Image stacks were either recorded manually or automatically with the newly released ZEISS Atlas 5 Array Tomography platform on a Zeiss FEGSEM. To characterize different populations of immune cells, organelle inventories were created by segmenting individual cells. In addition, arrays were used for quantification of cell populations with respect to the various cell types they contained. The detection of immunological synapses in cocultures of cell populations from thymus or WKM with cancer cells helped to identify the cytotoxic nature of these cells. Our results demonstrate the practicality and benefit of AT for high-throughput ultrastructural imaging of substantial volumes. LAY DESCRIPTION: To look at immune cells from zebrafish we employed array tomography, a technique where arrays of serial sections deposited on solid substrates are used for imaging. Cell populations were isolated from the different organs of zebrafish involved in haematopoiesis, the production of blood cells. They were chemically fixed and centrifuged to concentrate them in a pellet that was then dehydrated and embedded in resin. Using a custom-built handling device it was possible to place hundreds of serial sections on silicon wafers as well ordered arrays. To image a whole cell at a resolution that would allow identifying all the organelles (i.e. compartments surrounded by membranes) inside the cell, stacks of usually 50–100 images were recorded in a scanning electron microscope (SEM). This recording was either done manually or automatically using the newly released Atlas Array Tomography platform on a ZEISS SEM. For the imaging of the sections a pixel size of about 5 nm was chosen, which defines membrane boundaries very well and allows segmentation of the membrane topology. After alignment of the images, cellular components were segmented to locate the individual organelles within the 3D reconstruction of the whole cell and also to create an inventory of organelles. Based on their morphologies we could identify specific cell types in the different hematopoietic organs. We could also quantify the proportion of each cell type in the whole population isolated from a given organ. Some of these specific cells from zebrafish were grown in a culture dish together with human cancer cells. By time-lapse light microscopy we observed that the fish cells attacked the cancer cells and killed them. From this we concluded that these cells must be similar to the cytotoxic cells from humans that play an important role in defence against spontaneously arising cancer cells in our bodies. They form special structures, called immunological synapses that we could also identify on our arrays and reconstruct in 3D. This is the first time the potential of zebrafish immune cells to form immunological synapses has been demonstrated. Our study is a good example for the practicality and benefit of array tomography in high-throughput ultrastructure imaging of substantial volumes, applicable to many areas of cell and developmental biology

The long run relationship between private consumption and wealth : common and idiosyncratic effects

We investigate the long run relationship between private consump- tion, disposable income and wealth approximated by equity and house price indices for a panel of 15 industrialized countries. Consumption, income and wealth are cointegrated in their common components. The impact of house prices exceeds the effect arising from equity wealth. The long run vector is broadly in line with the life cycle permanent income hypothesis, if house prices are allowed to enter the relationship. At the idiosyncratic level, a long run equilibrium is detected between consumption and income, i.e. the wealth variable can be excluded. The income elasticity in the idiosyncratic relationship is significantly less than unity. Hence, the presence of wealth effects in consumption equations arises from the international integration of asset markets and points to the relevance of risk sharing activities of agents. Without sufficient opportunities, an increase in national saving rates would be expected, leading to a lower path of private consumption expenditures.info:eu-repo/semantics/publishedVersio