Genetic background strongly influences the bone phenotype of P2X7 receptor knockout mice

The purinergic P2X7 receptor is expressed by bone cells and has been shown to be important in both bone formation and bone resorption. In this study we investigated the importance of the genetic background of the mouse strains on which the P2X7 knock-out models were based by comparing bone status of a new BALB/cJ P2X7-/- strain with a previous one based on the C57BL/6 strain. Female four-month-old mice from both strains were DXA scanned on a PIXImus densitometer; femurs were collected for bone strength measurements and serum for bone marker analysis. Bone-related parameters that were altered only slightly in the B6 P2X7-/- became significantly altered in the BALB/cJ P2X7-/- when compared to their wild type littermates. The BALB/cJ P2X7-/- showed reduced levels of serum C-telopeptide fragment (s-CTX), higher bone mineral density, and increased bone strength compared to the wild type littermates. In conclusion, we have shown that the genetic background of P2X7-/- mice strongly influences the bone phenotype of the P2X7-/- mice and that P2X7 has a more significant regulatory role in bone remodeling than found in previous studies

Low-Energy Universality in Atomic and Nuclear Physics

An effective field theory developed for systems interacting through short-range interactions can be applied to systems of cold atoms with a large scattering length and to nucleons at low energies. It is therefore the ideal tool to analyze the universal properties associated with the Efimov effect in three- and four-body systems. In this "progress report", we will discuss recent results obtained within this framework and report on progress regarding the inclusion of higher order corrections associated with the finite range of the underlying interaction.Comment: Commissioned article for Few-Body Systems, 47 pp, 16 fig

Adiabatic Pair Creation

We give here the proof that pair creation in a time dependent potentials is possible. It happens with probability one if the potential changes adiabatically in time and becomes overcritical, that is when an eigenvalue enters the upper spectral continuum. The potential may be assumed to be zero at large negative and positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Suessmann in 1963 and Gershtein and Zeldovich in 1970.Comment: 53 pages, 1 figure. Editorial changes on page 22 f

Isolation Precautions for Visitors

Transmission of organisms within the hospital setting has become a topic of major concern not only for patients and healthcare facilities but also for government agencies and the general public. This increased awareness has occurred in part due to the spread of organisms that have limited treatment options, such as carbapenem-resistant Enterobacteriaceae (CRE), as well as the heightened recognition that many hospital-associated infections (HAIs) are preventable. A large body of literature shows that horizontal transmission of multidrug-resistant organisms involves the hands, and potentially the attire, of healthcare workers (HCWs). This evidence provides the rationale for the use of standard and contact isolation precautions among HCWs. However, the health risks to visitors and the role of visitors in the horizontal transmission of pathogens within acute care hospitals is not as clearly defined. Consequently, uncertainty remains regarding which precautions visitors should take when interacting with patients placed on isolation precautions. Frequent arguments against the use of isolation precautions among visitors include lack of visitor movement between patient rooms, the difficulty of educating visitors, and the difficulty of enforcing compliance with isolation practices

Electronic entropy, shell structure, and size-evolutionary patterns of metal clusters

We show that electronic-entropy effects in the size-evolutionary patterns of relatively small (as small as 20 atoms), simple-metal clusters become prominent already at moderate temperatures. Detailed agreement between our finite-temperature-shell-correction-method calculations and experimental results is obtained for certain temperatures. This agreement includes a size-dependent smearing out of fine-structure features, accompanied by a measurable reduction of the heights of the steps marking major-shell and subshell closings, thus allowing for a quantitative analysis of cluster temperatures.Comment: Latex/Revtex, 4 pages with 3 Postscript figure

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand

3-D Ultrastructure of O. tauri: Electron Cryotomography of an Entire Eukaryotic Cell

The hallmark of eukaryotic cells is their segregation of key biological functions into discrete, membrane-bound organelles. Creating accurate models of their ultrastructural complexity has been difficult in part because of the limited resolution of light microscopy and the artifact-prone nature of conventional electron microscopy. Here we explored the potential of the emerging technology electron cryotomography to produce three-dimensional images of an entire eukaryotic cell in a near-native state. Ostreococcus tauri was chosen as the specimen because as a unicellular picoplankton with just one copy of each organelle, it is the smallest known eukaryote and was therefore likely to yield the highest resolution images. Whole cells were imaged at various stages of the cell cycle, yielding 3-D reconstructions of complete chloroplasts, mitochondria, endoplasmic reticula, Golgi bodies, peroxisomes, microtubules, and putative ribosome distributions in-situ. Surprisingly, the nucleus was seen to open long before mitosis, and while one microtubule (or two in some predivisional cells) was consistently present, no mitotic spindle was ever observed, prompting speculation that a single microtubule might be sufficient to segregate multiple chromosomes

Overcoming the barriers to greater public engagement

Integrating science communication training into an undergraduate research project encourages greater academic involvement in public engagement, maximizes audience size, and provides high-quality research data

Determinantes Nacionais e Setoriais da Estrutura de Capital na América Latina

This study identified the role of the national environment (the Macroeconomy, Financial Development and Institutional Quality) and industry characteristics (Munificence, Dynamism, Concentration, Life Cycle, Technological Efficiency Dispersion, Product Quality Dispersion, Customer Bargaining Power and Supplier Bargaining Power) on debt of 612 listed companies from 7 Latin American countries (Argentina, Brazil, Chile, Colombia, Mexico, Peru and Venezuela). For comparison purposes, the analysis is also extended to 847 U.S. companies. The period of study is 1996-2009 and the analysis employed a Hierarchical Linear Model, which controls the effects according to the level of the variables (country, industry, time and firm). The results suggest that Financial Development eases access to external funds and Institutional Quality is negatively related to firm Leverage. The research also finds evidence that institutional quality can promote asymmetrical development between stock markets and credit markets