Mineral fabrication and golgi apparatus activity in the mouse calvarium

There is diverse opinion about the mechanism of bone mineralization with only intermittent reports of any direct organellar role played by the golgi apparatus (juxtanuclear body). Light and laser confocal microscopy was combined with electron microscopy and elemental EDX (energy dispersive X-ray microanalysis) in comparing “young” osteocytes in situ in fresh and “slam” frozen developing mouse calvarium, with similar cells (MC3T3-E1) maintained in vitro. The distribution of “nascent” electron dense mineral was examined histochemically (von Kossa, GBHA), including tetracycline (TC) staining as a fluorescent complex with bone salt, while golgi body activity was demonstrated by transfection with a specific green fluorescent construct (GFP/mannosidase II). In tissue culture golgi body activity and mineralization were both blocked by brefeldin A (an established golgi inhibitor) and restored by forskolin, enabling an association with mineral fabrication to be quantified as changing fluorescence intensity (AU) of GFP or TC markers. Results from osteocytes in situ supported previous descriptions of intracellular electron dense objects (microspheres and nanospheres) in a juxtanuclear pattern, containing Ca, P and transitory Si, in a spectrum recapitulated in the calcifying culture after 10 days, when GFP fluorophore surged from 71.7 ± 1.4SD to 133.7 ± 2.7SD AU by 14 days (p < 0.0001). At this stage TC fluorophore mean intensity was 23.8 ± 3.7SD AU (14 days) rising to 45.0 ± 5.1SD AU by 17 days, compared to its stationary 21.7 ± 3.6SD when treated 3 days previously with BFA golgi inhibitor (p < 0.0001), until forskolin reversal. It was concluded from the changing juxtanuclear morphology, Si mineralization mediation and the variably controlled activity versus stasis that the inorganic phase of bone is a complex golgi-directed fabrication with implications for bone matrix biology and evolution

Compressive force generation by a bundle of living biofilaments

To study the compressional forces exerted by a bundle of living stiff filaments pressing on a surface, akin to the case of an actin bundle in filopodia structures, we have performed particulate Molecular Dynamics simulations of a grafted bundle of parallel living (self-assembling) filaments, in chemical equilibrium with a solution of their constitutive monomers. Equilibrium is established as these filaments, grafted at one end to a wall of the simulation box, grow at their chemically active free end and encounter the opposite confining wall of the simulation box. Further growth of filaments requires bending and thus energy, which automatically limit the populations of longer filaments. The resulting filament sizes distribution and the force exerted by the bundle on the obstacle are analyzed for different grafting densities and different sub- or supercritical conditions, these properties being compared with the predictions of the corresponding ideal confined bundle model. In this analysis, non-ideal effects due to interactions between filaments and confinement effects are singled out. For all state points considered at the same temperature and at the same gap width between the two surfaces, the force per filament exerted on the opposite wall appears to be a function of a rescaled free monomer density $\hat{\rho}_1^{\rm eff}$. This quantity can be estimated directly from the characteristic length of the exponential filament size distribution $P$ observed in the size domain where these grafted filaments are not in direct contact with the wall. We also analyze the dynamics of the filament contour length fluctuations in terms of effective polymerization ($U$) and depolymerization ($W$) rates, where again it is possible to disentangle non-ideal and confinement effects.Comment: 24 pages, 7 figure

Damping of liquid sloshing by foams: from everyday observations to liquid transport

We perform experiments on the sloshing dynamics of liquids in a rectangular container submitted to an impulse. We show that when foam is placed on top of the liquid the oscillations of the free interface are significantly damped. The ability to reduce sloshing and associated splashing could find applications in numerous industrial processes involving liquid transport.Comment: Accepted for publication in Journal of Visualizatio

Name and shame the impact of the ofsted model of school inspection on the working lives of primary teachers: an ethnographic study

The question the study seeks to address is what kind of effects primary teachers experience before, during and after an inspection by the Office for Standards in Education (Ofsted). The focus of the study is the classroom and staffroom interaction of teachers in a small primary school serving a disadvantaged estate in the North of England. Working as a voluntary classroom assistant in each of the classes in the school throughout the school's Ofsted year, the researcher adopts the role of participant observer, noting the teachers' response to the Ofsted process, as evidenced in their day-to-day activities and interaction. The study begins by explaining the researcher's interest in this area of study and approach, then sets this against the background of recent research into the work of teachers in English primary schools. In Chapter Three, the practicalities of undertaking fieldwork in the school are explored, relating these to literature which the researcher found particularly helpful in making sense of the realities of undertaking an ethnographic approach in this environment. An outline sketch of the background to school inspection in the UK is undertaken in Chapter Four to place the experiences of the teachers in context. The major part of the study, in Chapter Five, is given over to the story of Banktop School's Ofsted year, as observed by the researcher working as "another pair of hands" in the classroom. The analysis of this data in Chapter Six draws attention to three main themes throughout the year - the anxiety of the teachers; their view of Ofsted as separate from their own values in their day-to-day work; the stress on public performance as central to successful assessment by Ofsted. In the final chapter, the experiences of the year are viewed in context of the research reviewed in Chapter Two and consideration is given to the limitations of the methodology. The usefulness of the Ofsted model of school inspection in the professional development of primary teachers is questioned

The Privileges and Immunities Clause: A Reaffirmation of Fundamental Rights

In this note, the author examines the continuing debate over the role of the judiciary in reviewing state legislative acts and indicates the continued reluctance of the Supreme Court of the United States to expand the content of rights protected under the privileges and immunities clause of article IV and the fourteenth amendment. The author concludes that the present refusal of the Court to impose its own value judgments over those of the state legislature is consistent with the purpose and past interpretation of the privileges and immunities clause, absent a conflict with other rights of the Constitution

The Privileges and Immunities Clause: A Reaffirmation of Fundamental Rights

In this note, the author examines the continuing debate over the role of the judiciary in reviewing state legislative acts and indicates the continued reluctance of the Supreme Court of the United States to expand the content of rights protected under the privileges and immunities clause of article IV and the fourteenth amendment. The author concludes that the present refusal of the Court to impose its own value judgments over those of the state legislature is consistent with the purpose and past interpretation of the privileges and immunities clause, absent a conflict with other rights of the Constitution

On the Properties of a Bundle of Flexible Actin Filaments in an Optical Trap

We establish the Statistical Mechanics framework for a bundle of Nf living and uncrosslinked actin filaments in a supercritical solution of free monomers pressing against a mobile wall. The filaments are anchored normally to a fixed planar surface at one of their ends and, because of their limited flexibility, they grow almost parallel to each other. Their growing ends hit a moving obstacle, depicted as a second planar wall, parallel to the previous one and subjected to a harmonic compressive force. The force constant is denoted as trap strength while the distance between the two walls as trap length to make contact with the experimental optical trap apparatus. For an ideal solution of reactive filaments and free monomers at fixed free monomers chemical potential, we obtain the general expression for the grand potential from which we derive averages and distributions of relevant physical quantities, namely the obstacle position, the bundle polymerization force and the number of filaments in direct contact with the wall. The grafted living filaments are modeled as discrete Wormlike chains, with Factin persistence length, subject to discrete contour length variations to model single monomer (de)polymerization steps. Rigid filaments, either isolated or in bundles, all provide average values of the stalling force in agreement with Hill's predictions, independent of the average trap length. Flexible filaments instead, for values of the trap strength suitable to prevent their lateral escape, provide an average bundle force and an average trap length slightly larger than the corresponding rigid cases (few percents). Still the stalling force remains nearly independent on the average trap length, but results from the product of two strongly L dependent contributions: the fraction of touching filaments and the single filament buckling force.Comment: 21 pages, 8 figure

Understanding the information needs of users of public information about higher education

Report to HEFCE by Oakleigh Consulting and Staffordshire University. "This study's aims were to carry out research into understanding the needs of intended users (primarily prospective students but with some focus on their advisors and employers) of public information on higher education (HE). The work focussed on England, but also took into account Wales, Scotland and Northern Ireland where relevant." - Page 1

Nuclear Envelope, Nuclear Lamina, and Inherited Disease

The nuclear envelope is composed of the nuclear membranes, nuclear lamina, and nuclear pore complexes. In recent years, mutations in nuclear-envelope proteins have been shown to cause a surprisingly wide array of inherited diseases. While the mutant proteins are generally expressed in most or all differentiated somatic cells, many mutations cause fairly tissue-specific disorders. Perhaps the most dramatic case is that of mutations in A-type lamins, intermediate filament proteins associated with the inner nuclear membrane. Different mutations in the same lamin proteins have been shown to cause striated muscle diseases, partial lipodystrophy syndromes, a peripheral neuropathy, and disorders with features of severe premature aging. In this review, we summarize fundamental aspects of nuclear envelope structure and function, the inherited diseases caused by mutations in lamins and other nuclear envelope proteins, and possible pathogenic mechanisms

Fault and Equity: Implied Indemnity After \u3cem\u3eHoudaille\u3c/em\u3e

This article examines the doctrine of implied indemnity in light of the recent decision of the Supreme Court of Florida in Houdaille Industries, Inc. v. Edwards. The authors discuss the meaning of fault and no fault in terms of the mechanisms of accident law, develop three models for allocating accident losses, and evaluate the change in accident law introduced in Houdaille, concluding that the court achieved conceptual consistency at the expense of equity