Formin isoforms are differentially expressed in the mouse embryo and are required for normal expression of fgf-4 and shh in the limb bud

Mice homozygous for the recessive limb deformity (ld) mutation display both limb and renal defects. The limb defects, oligodactyly and syndactyly, have been traced to improper differentiation of the apical ectodermal ridge (AER) and shortening of the anteroposterior limb axis. The renal defects, usually aplasia, are thought to result from failure of ureteric bud outgrowth. Since the ld locus gives rise to multiple RNA isoforms encoding several different proteins (termed formins), we wished to understand their role in the formation of these organs. Therefore, we first examined the embryonic expression patterns of the four major ld mRNA isoforms. Isoforms I, II and III (all containing a basic amino terminus) are expressed in dorsal root ganglia, cranial ganglia and the developing kidney including the ureteric bud. Isoform IV (containing an acidic amino terminus) is expressed in the notochord, the somites, the apical ectodermal ridge (AER) of the limb bud and the developing kidney including the ureteric bud. Using a lacZ reporter assay in transgenic mice, we show that this differential expression of isoform IV results from distinct regulatory sequences upstream of its first exon. These expression patterns suggest that all four isoforms may be involved in ureteric bud outgrowth, while isoform IV may be involved in AER differentiation. To define further the developmental consequences of the ld limb defect, we analyzed the expression of a number of genes thought to play a role in limb development. Most significantly, we find that although the AERs of ld limb buds express several AER markers, they do not express detectable levels of fibroblast growth factor 4 (fgf-4), which has been proposed to be the AER signal to the mesoderm. Thus we conclude that one or more formins are necessary to initiate and/or maintain fgf-4 production in the distal limb. Since ld limbs form distal structures such as digits, we further conclude that while fgf-4 is capable of supporting distal limb outgrowth in manipulated limbs, it is not essential for distal outgrowth in normal limb development. In addition, ld limbs show a severe decrease in the expression of several mesodermal markers, including sonic hedgehog (shh), a marker for the polarizing region and Hoxd-12, a marker for posterior mesoderm. We propose that incomplete differentiation of the AER in ld limb buds leads to reduction of polarizing activity and defects along the anteroposterior axis

Relativistic Quasilinear Diffusion in Axisymmetric Magnetic Geometry for Arbitrary-Frequency Electromagnetic Fluctuations

A relativistic bounce-averaged quasilinear diffusion equation is derived to describe stochastic particle transport associated with arbitrary-frequency electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for the elements of a relativistic quasilinear diffusion tensor are calculated explicitly for magnetically-trapped particle distributions in axisymmetric magnetic geometry in terms of gyro-drift-bounce wave-particle resonances. The resonances can destroy any one of the three invariants of the unperturbed guiding-center Hamiltonian dynamics.Comment: 22 pages, Latex, to appear in Physics of Plasma

Risk and Return on Real Estate: Evidence from Equity REITs

We analyze monthly returns on an equally-weighted index of 18 to 23 equity (real property) real estate investment trusts (REITs) that were traded on major stock exchanges over the 1973-87 period. We employ a multifactor Arbitrage Pricing Model using prespecified macroeconomic factors. We also test whether equity REIT returns are related to changes in the discount on closed-end stock funds, which seems plausible given the closed-end nature of REITs. Three factors, and the percentage change in the discount on closed-end stock funds, consistently drive equity REIT returns: unexpected inflation and changes in the risk and term structures of interest rates. The impacts of these variables on equity REIT returns is around 60 percent of the impacts on corporate stock returns generally. As expected, the impacts are greater for more heavily levered REITs than for less levered REITs. Real estate, at least as measured by the return performance of equity REITs, is less risky than stocks generally, but does not offer a superior risk-adjusted return and is not a hedge against unexpected inflation.

Implementation of enterprise resource planning (ERP) software in a major construction contracting organization in Hong Kong

Purpose &ndash; The purpose of this paper is to summarize the scope, methodology and main findings of a doctoral thesis about the implementation of enterprise resource planning (ERP) software in a major construction contracting organization in Hong Kong. This research is taken from a leadership and power and project management (PM) perspective.Design/methodology/approach &ndash; The project adopted a case study approach in which the candidate was an employee/observer, who was embedded as a member of the business transformation team taking an action learning approach to study the ERP adoption. The research used the soft system methodology to identify gaps in the observed maturity level which exists in the organization. Data was gathered using public and private documentation, semi-structured interviews, observation and was validated through review of evidence with participants.Findings &ndash; The results identified the importance of leadership and cultural issues in implementation of the business strategy. This research includes a contribution in two spheres: PM and construction procurement. The first implication for PM theory was to illustrate how knowledge has been efficiently managed within a construction organization by using information communication technology (ICT). It can be represented by the ladder of ICT&gt;ERP&gt;KM&gt;PM. The second implication was to pave the way for the use of partnering strategies in PM practice. It can be represented by the ladder of National Culture&gt;Organizational Culture&gt;Leadership&gt;Partnering Strategy&gt;PM.Practical implications &ndash; This model could be adapted to other large and complex organisational contexts. The research project also has implications as opening up a PM perspective on business transformation.Originality/value &ndash; The contribution of this research is proving the success of adopting KM in a construction company by using an ERP system. The importance of culture in the traditionally collectivistic construction industry, and the issues senior management should take into account when formulating business strategies.<br /