A chemically driven fluctuating ratchet model for actomyosin interaction

With reference to the experimental observations by T. Yanagida and his co-workers on actomyosin interaction, a Brownian motor of fluctuating ratchet kind is designed with the aim to describe the interaction between a Myosin II head and a neighboring actin filament. Our motor combines the dynamics of the myosin head with a chemical external system related to the ATP cycle, whose role is to provide the energy supply necessary to bias the motion. Analytical expressions for the duration of the ATP cycle, for the Gibbs free energy and for the net displacement of the myosin head are obtained. Finally, by exploiting a method due to Sekimoto (1997, J. Phys. Soc. Jpn., 66, 1234), a formula is worked out for the amount of energy consumed during the ATP cycle.Comment: 15 pages. 1 figur

An Appreciative Approach to Diversity Training

One way to combat "diversity fatigue" is to take an appreciative approach to diversity training. This article highlights the six phases of Appreciative Education and how diversity trainers can use specific activities for each phase to deliver effective diversity training

Intravenous digital subtraction angiography in the assessment of patients with left to right shunts before and after surgical correction

Pre- and postoperative structural changes and pulmonary to systemic flow (QP/QS) ratios were assessed using digital angiography in 34 patients documented to have a left to right shunt at cardiac catheterization. There were 16 men and 18 women whose ages ranged from 4 months to 60 years. The radiographic single mask mode was used for all digital subtraction angiographic studies with a typical radiographic sequence being 80 to 100 kV, 5 to 10 mA/frame at six frames/s for 15 seconds. Renografin-76 was used as a bolus injection at 0.5 to 1.0 ml/kg via an arm vein in most patients. The level of the left to right shunt and any associated anomalies were noted and compared with results from cardiac catheterization. Digital subtraction angiographic flow curves were generated from the pulmonary arteries, and QP/QS ratios were calculated pre- and postoperatively using the gamma variate fit method and compared with the QP/QS ratio from first pass radionuclide studies.A strong correlation between preoperative digital subtraction angiographically derived QP/QS ratio and radionuclide-derived QP/QS ratio was found, with an r value equal to 0.89, p < 0.0001. Postoperatively, all patients had a QP/QS ratio less than 1.2:1.0 for both digital subtraction angiography and radionuclide studies. The level of left to right shunt was accurately assessed in all patients, and its absence observed postoperatively. Associated anomalies, such as a persistent left superior vena cava, coarctation of the aorta and partial anomalous venous return, were identified in all cases.Intravenous digital subtraction angiography provides accurate quantitative and anatomic data in patients with a left to right shunt, is potentially an important outpatient method to assess adequate surgical correction and may suffice preoperatively to proceed to cardiac surgery without preoperative cardiac catheterization

The control challenges for the Next Generation Gravity Mission

Several activities are on going in preparation of a "Next Generation Gravity Mission" (NGGM) aimed at measuring the temporal variations of the Earth gravity field over a long time span with high spatial resolution and high temporal resolution. The most appropriate measurement technique identified for such mission is the "Low-Low Satellite-Satellite Tracking" in which two satellites flying in loose formation in a low Earth orbit act as proof masses immersed in the Earth gravity field. The distance variation between the satellites and the non-gravitational accelerations of the satellites, measured respectively by a laser interferometer and by ultra-sensitive accelerometers, are the fundamental observables from which the Earth gravitational field is obtained. The control system for the NGGM must fulfil the challenging combination of requirements for the orbit and formation maintenance, attitude stabilisation, drag compensation and microradian laser beam pointing. This paper presents the assessment and the preliminary design of the NGGM control system, performed by Thales Alenia Space Italia and Politecnico di Torino for the European Space Agency

Wind direction data from a coastal HF radar system in the gulf of naples (central mediterranean sea)

Results on the accuracy of SeaSonde High Frequency (HF) radar wind direction measurements in the Gulf of Naples (Southern Tyrrhenian Sea, Central Mediterranean Sea) are here presented. The investigation was carried out for a winter period (2 February-6 March) and for one summer month (August) of the reference year 2009. HF radar measurements were compared with in situ recordings from a weather station and with model data, with the aim of resolving both small scale and large scale dynamics. The analysis of the overall performance of the HF radar system in the Gulf of Naples shows that the data are reliable when the wind speed exceeds a 5 m/s threshold. Despite such a limitation, this study confirms the potentialities of these systems as monitoring platforms in coastal areas and suggests further efforts towards their improvement

A Patient with Proopiomelanocortin Deficiency: An Increasingly Important Diagnosis to Make

Proopiomelanocortin (POMC) deficiency is a rare monogenic disorder with early-onset obesity. Investigation of this entity have increased our insight into the important role of the leptin-melanocortin pathway in energy balance. Here, we present a patient with POMC deficiency due to a homozygous c.206delC mutation in the POMC gene. We discuss the pathogenesis of this condition with emphasis on the crosstalk between hypothalamic and peripheral signals in the development of obesity and the POMC-melanocortin 4 receptors system as a target for therapeutic intervention