acase@tulane.edu

acase@tulane.edu

This paper matches four different classes of axisymmetric solutions to Einstein's Field equations (Weyl and Levi-Civita static solutions, Kerr solution, Papapetrou solutions or Lewis and Van Stockum solutions) across a thin axisymmetric rotating shell to a flat interior metric. No assumptions about the behavior of the gravitational field at infinity are imposed, including the usual assumptions of asymptotic flatness or compactness. The purpose is to see how changing the boundary conditions at infinity affects frame dragging inside the shell The first case discussed is that of a spherical rigidly rotating shell of uniform density. Excluding the limit of the shell radius equal to the gravitational radius, the only matching exterior solutions finite on the rotation axis are trivial flat and Schwarzschild metrics. The freedom gained by not imposing boundary conditions at infinity is not sufficient to allow other matchings across such a shell to a flat interior metric Allowing the shell to be any of a class of axisymmetric prolate spheroidal shells with rotation and density dependent on latitude, I find matchings in cases other than the gravitational limit for both the Weyl and Levi-Civita static case and the Papapetrou case. Both contain asymptotically flat solutions as well as solutions with other behavior at infinity. The component of the stress energy tensor for time and angle of rotation as seen in an inertial frame is zero in the Weyl and Levi-Civita static case for all boundary conditions. It may however be nonzero in the Papapetrou case depending upon the conditions at infinity imposed. The interpretation is that changing the boundary conditions in this case changes the frame dragging of the interior inertial frames / acase@tulane.edu

We present a method to automatically construct features capable of putting images in correspondence with each other (i.e. registration) without requiring control points or landmarks on the images in question. It is clear that a technique is required for analyzing the dependence structure inside an image. Typically images have a high degree of correlation, thus having redundant information within the image set. Transforming the set of images into its principal components results in a data set where the resulting information is uncorrelated, thus eliminating the redundancies. Our method is based primarily on Principal Component Analysis (PCA) and a suitable image representation, The feature set is a collection of weight vectors and the correspondence mapping is done using the distances between those vectors. Only a small number of vectors is needed. While we illustrate the approach in the context of image registration, other applications of this method are possible, like distributed sensor networks specifically when a sensor network is build up observing devices, like camcorders, CCDs, etc. Most notably, the method could be used for image matching and retrieval, being insensitive to rotation / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

Multipotent Stromal Cells (MSCs) hold great promise for future cell-based therapeutics. By understanding the mechanisms by which MSCs contribute to tissue repair, not only can insight be gained as to their potential applications, but novel therapeutic candidates can be identified as well. We determined that MSCs were activated by apoptotic cells to upregulate and secrete Stanniocalcin-1 (STC1), a highly evolutionarily-conserved mineral-regulating protein hypothesized to be stress-responsive in mammals. We determined that STC1 was required for the MSCs to elicit an anti-apoptotic effect on injured cells in two in vitro models of apoptosis. In the first model, STC1 was required but not sufficient to reduce apoptosis of fibroblasts that had been UV-irradiated. In the second model, STC1 was both required and sufficient to reduce apoptosis of ischemic lung epithelial cells. We then tested the stress-responsive nature of STC1 more directly by adopting a model of injury that allowed us to visualize calcium dynamics immediately following insult. We demonstrated that STC1 dramatically enhanced calcium wave propagation following mechanical stimulation of an epithelial monolayer. We showed that the propagation of the calcium wave was dependent on extracellular nucleotides, and that STC1 enhanced the calcium response downstream of extracellular ATP. Blocking STC1 inhibited the propagation of the calcium wave as well as the ATP-induced calcium response indicating that STC1 was required for ATP signaling. These novel data provide mechanistic grounds for the pleiotropic nature of STC1 and may have profound implications on the application of STC1 as a therapeutic target considering the ubiquity of ATP signaling in various biological processes / acase@tulane.edu

Satellite associations (SA's) of the human acrocentric chromosomes, which are commonly seen in metaphase spreads, result from joint nucleolus formation during the preceding interphase. Silver staining is specific for those nucleolar organizer regions (NOR's) which produced rRNA during the preceding interphase. Thus, both SA and silver staining result from nucleolar activity. However, the two aspects of nucleolar activity are not inseparable. Some SA's contain silver-negative acrocentrics are not always found in SA SA's were scored in 2800 metaphase cells from fourteen individuals. Two different criteria for SA were used: (1) acrocentrics with visible silver connectives (SC's) between them were scored; (2) acrocentrics were scored if the measured distance between their short arms was no greater than the long arm length of chromosome 21 Less than 2% of the total acrocentrics in SA scored using both criteria were silver-negative. However, almost 20% of those scored using the distance criterion were silver-negative. The presence of silver-negative chromosomes in SA indicates that some SA's are spurious. If only silver-connected acrocentrics are considered to be in association, then approximately 9% of the SA's were spurious. If the distance criterion is allowed, then about 3% of the total were spurious The same 2800 metaphases were used to screen for associations between NOR's and the heterochromatic regions of the non-acrocentrics. Of the 800 acrocentrics thus associated, 597 were joined by SC's to heterochromatin. Approximately half of the total associations were with the C-bands of chromosomes 1, 9 and 16. A positive correlation between C-band size and number of associations was found. Additionally, in heteromorphic C-bands most associations were with the larger C-band of the homologous pair The distribution of SC associations with heterochromatin was not random with respect to the amount of heterochromatin in each C-band. Chromosomes 1 and 2 had more associations than expected, and chromosomes 17, 18, 19, 20 and Y had fewer. Although the number of SC overlaps of euchromatin was far less than of heterochromatin, the pattern of distribution was similar / acase@tulane.edu

The tertiary phosphine/secondary amide and amine hybrid ligands o-(diphenylphosphino)-N-phenylbenzamide (P(CO)NHPh), o-(diphenylphosphino)-N-benzoylaniline (PNH(CPhO), o-(diphenyl- phosphino)-N-phenylbenzylamine (PCNHPh), and o-(diphenyl- phosphino)-N-benzylaniline (PNHBz) have been synthesized and characterized. PNH(CPhO) undergoes N-H oxidative addition with IrL(,2)Cl (L = 2PPh(,3), 2AsPh(,3), 1,2-(Ph(,2)P)(,2)C(,2)H(,4)) to give a mixture of two isomers of the Ir(III) amido hydride(' )Ir PN(CPhO) L(,2)(H)Cl. The possible structures of these isomers are discussed on the basis of their spectroscopic properties (('31)P nmr, ('1)H nmr, and infrared). The reactions of IrL(,2)Cl and the other hybrid ligands give similar results. The oxidative addition reaction of the N-H moiety of a secondary benzamide or aniline and IrL(,2)Cl does not occur in the absence of the chelate effect. Neither PNH(CPhO) nor P(CO)NHPh undergo N-H oxidative addition with either M(cod)Cl (,2) or M(cod)(THF)(,2) - ClO(,4) (M = Rh, Ir; cod = 1,5-cyclooctadiene); instead M(I) phosphine complexes are obtained. The hybrid ligands were used to prepare the chelate-stabilized amido complexes (cod)M(P N)(' )(M = Rh, P(' )N(' )= PN(CPHO), P(CO)NPh; M = Ir, P N = P(CO)NPh) and Ir PN(CPhO) (cod)H(Cl).(' )The properties of these rhodium and iridium complexes are discussed. PNH(CPhO) and P(CO)NHPh coordinate to M(II) (M = Pd, Pt) via the phosphorus atom to give the complexes ML(,2)Cl(,2) (L = hybrid ligand). Deprotonation of the nitrogen atom of these complexes gives the bis(amido) complexes M(P(' )N)(,2) (P N(' )= PN(CPhO), P(CO)NPh). The Pd(II) bis(amido) complexes were also prepared by the reaction of the hybrid ligands and Pd(,2)(dba)(,3) (dba = dibenzylideneacetone). The cyclometallated amido complexes(' )M o-Ph(,2)PC(,6)H(,4)NC(O)C(,6)H(,4) PNH(CPhO) (M = Pd, Pt) have been synthesized. The structure of the Pt complex was determined by a single crystal X-ray diffraction study. The solid state molecular structure is best described as a square pyramid with the NH moiety of the PNH(CPhO) ligand residing in the apical position. A short Pt-H distance of 2.46 A was found, and this interaction may be important in the H/D exchange reaction between the NH proton of these amido complexes and deuterated solvents. The reactivity of the palladium and platinum amido complexes was examined / acase@tulane.edu

acase@tulane.edu