Reputation

We explain what reputation effects are, how they arise and the factors that limit or strengthen them

Dealer behaviour and price volatility in asset markets

Macroeconomic Models

Twist Is Required for Muscle Template Splitting during AdultDrosophilaMyogenesis

AbstractThe basic helix–loop–helix transcription factor Twist is required for normal development of larval and adult somatic muscles inDrosophila.Adult flies normally have six pairs of dorsal longitudinal indirect flight muscles (DLMs), whereas when Twist function is reduced, only three pairs of DLMs are formed. Althoughtwistis expressed in precursors of adult muscles throughout the larval and early pupal stages, we demonstrate that Twist function is required only during the late larval stage for DLM patterning. In wild-type flies, this is just prior to the time when three pairs of persistent larval muscle fibers split longitudinally to form templates for the six pairs of DLMs. By examining sections at various times during pupal development, we found that splitting of the larval muscles does not occur intwistmutants, indicating that Twist function is required to induce major changes in the larval templates prior to differentiation. The function of Twist in larval muscle splitting is likely mediated by myocyte enhancer factor-2 (MEF2) since inMef2hypomorphic mutants splitting is also reduced andMef2expression is dependent upon Twist. Our findings define specific roles for Twist and MEF2 during pupal myogenesis and demonstrate that these transcription factors function in adult muscle precursor cells to regulate downstream factors controlling muscle cell splitting and morphogenesis

Pharmaceutical transition to non-CFC pressurized metered dose inhalers

The production of ozone-depleting chlorofluorocarbons (CFCs) was discontinued on 1 January 1996 for all uses deemed non-essential under the Montreal Protocol. However, the use of CFCs as propellants in pressurized metered dose inhalers (pMDIs) was classed as essential, providing an exemption from the agreement. Following extensive research, the hydrofluoroalkanes (HFA) 134a and 227 were identified as the only suitable replacements for CFC propellants in pMDIs.The drug delivery of pMDIs formulated with HFA 134a as a propellant and containing either salbutamol (100 μg per actuation) or fluticasone propionate (125 and 250 μg per actuation) have been assessed for dose uniformity and particle size distribution.All of the HFA 134a pMDIs delivered doses throughout the life of the canisters that were reproducible and within specified regulatory requirements. Each of the products provided an emitted dose which was within ±25% of the mean value indicating accurate and consistent dosing (93, 112 and 221 μg per metered dose for the salbutamol 100 μg and fluticasone propionate 125 and 250 μg HFA 134a pMDIs, respectively). These findings were unaffected by changing the storage orientation of the pMDI or by using the device in a manner designed to simulate typical patient use. The particle size distributions of HFA 134a pMDI doses did not differ significantly from those of the corresponding CFC pMDIs. As a result of the similar pharmaceutical performance, it is unnecessary to change the label claim dose of active drug when making the transition from a CFC to an HFA 134a pMDI for salbutamol (VentolinTM) and fluticasone propionate (FlixtideTM). A seamless transition to non-CFC pMDIs will help to maintain the confidence of patients and healthcare professionals in asthma therapy

The effect of farming system on dairy cow cleanliness in the UK and implications to udder health

The cleanliness of dairy cows was assessed using a 20 point hygiene score system at different times in the year on 14 organic and 14 conventional farms in the UK. Overall, cows were dirtier during winter housing compared to summer grazing. Farming system had no effect on cow cleanliness when cows were at grass, but when housed in the winter, organic cows were more likely to be cleaner. There was a link between cow hygiene scores and milk hygiene, with herds having lower bulk tank somatic cell counts (BTSCC) tending to have cleaner cows. This relationship was strongest for the organic herds. There was no significant link between hygiene score and Bactoscan (BS) count or mastitis incidence

Singularities in five-axis machining:cause, effect and avoidance

Singular configurations of five-axis machines have long been observed. Machining near to such singularities drastically affects the behaviour of machine axes movements. Singularities have been linked to the kinematic chain of the machine configuration but not necessarily machine axes movement. The first contribution of this paper is a link between cutter motion in work-piece and machine coordinate systems. This leads to a description for the machine axes movements for a given tool path. Unstable machine axes movements are discovered near singular configurations of the rotary axes. By relating these configurations to orientations in the workpiece coordinate system, a simple approach that avoids singularities by reorienting the workpiece is proposed. Machining tests verify the effectiveness of this approach.</p