Relative biological effectiveness (RBE) and out-of-field cell survival responses to passive scattering and pencil beam scanning proton beam deliveries

The relative biological effectiveness (RBE) of passive scattered (PS) and pencil beam scanned (PBS) proton beam delivery techniques for uniform beam configurations was determined by clonogenic survival. The radiobiological impact of modulated beam configurations on cell survival occurring in- or out-of-field for both delivery techniques was determined with intercellular communication intact or physically inhibited. Cell survival responses were compared to those observed using a 6 MV photon beam produced with a linear accelerator. DU-145 cells showed no significant difference in survival response to proton beams delivered by PS and PBS or 6 MV photons taking into account a RBE of 1.1 for protons at the centre of the spread out Bragg peak. Significant out-of-field effects similar to those observed for 6 MV photons were observed for both PS and PBS proton deliveries with cell survival decreasing to 50-60% survival for scattered doses of 0.05 and 0.03 Gy for passive scattered and pencil beam scanned beams respectively. The observed out-of-field responses were shown to be dependent on intercellular communication between the in-and out-of-field cell populations. These data demonstrate, for the first time, a similar RBE between passive and actively scanned proton beams and confirm that out-of-field effects may be important determinants of cell survival following exposure to modulated photon and proton fields

The colonization of macroalgal rafts by the genus Idotea (sub-phylum Crustacea; Order Isopoda):An active or passive process?

The association of invertebrate communities with macroalgae rafts has received much attention over recent decades, yet significant gaps in our knowledge remain with respect to the colonization process. Using laboratory-based experiments and in situ field trials in Strangford Lough, Northern Ireland, this study investigated whether members of the known rafting genus Idotea (sub-phylum Crustacea; order Isopoda) could effectively colonize rafts after shore seaweed detachment, or if their presence merely reflected a passive marooning process. Test tank arenas were used to identify traits that may influence the rafting potential of the dominant shore species Idotea granulosa and the well known rafter Idotea baltica. When released mid-water, I. granulosa initially ascended and associated with floating seaweed whereas I. baltica tended to descend with no clear habitat association. These findings conflict with the differential distribution of these Idotea species among rafts and shore algae, thus highlighting the complex nature of the potential of organisms to raft. In the field we considered the relative ability of different Idotea species to colonize tethered rafts composed of Ascophyllum nodosum and Fucus vesiculosus, cleaned of all vagile organisms and deployed at locations adjacent to established intertidal Idotea species populations. At the end of the experiment (after 44 days) rafts were inhabited by known rafting and shoreline species, confirming that colonization can occur after algal detachment. Previously considered shoreline species on occasion outnumbered well known rafters suggesting that a wide range of Idotea species can readily avail of macroalgal rafts as a potential dispersal mechanism or alternative habitat. © 2012 Marine Biological Association of the United Kingdom.

Adherence to antiepileptic medicines in children: A multiple-methods assessment involving dried blood spot sampling

Purpose: To evaluate adherence to prescribed antiepileptic drugs (AEDs) in children with epilepsy using a combination of adherence-assessment methods.
Methods: A total of 100 children with epilepsy (=17 years old) were recruited. Medication adherence was determined via parental and child self-reporting (=9 years old), medication refill data from general practitioner (GP) prescribing records, and via AED concentrations in dried blood spot (DBS) samples obtained from children at the clinic and via self- or parental-led sampling in children's own homes. The latter were assessed using population pharmacokinetic modeling. Patients were deemed nonadherent if any of these measures were indicative of nonadherence with the prescribed treatment. In addition, beliefs about medicines, parental confidence in seizure management, and the presence of depressed mood in parents were evaluated to examine their association with nonadherence in the participating children.
Key Findings: The overall rate of nonadherence in children with epilepsy was 33%. Logistic regression analysis indicated that children with generalized epilepsy (vs. focal epilepsy) were more likely (odds ratio [OR] 4.7, 95% confidence interval [CI] 1.37-15.81) to be classified as nonadherent as were children whose parents have depressed mood (OR 3.6, 95% CI 1.16-11.41).
Significance: This is the first study to apply the novel methodology of determining adherence via AED concentrations in clinic and home DBS samples. The present findings show that the latter, with further development, could be a useful approach to adherence assessment when combined with other measures including parent and child self-reporting. Seizure type and parental depressed mood were strongly predictive of nonadherence. © 2013 International League Against Epilepsy.
Key Words: Adherence, Epilepsy, Dried blood spots, MARS, Depressed mood.

Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

Biotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e. g. predators); thus, it is often assumed that species' distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e. g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

A wideband antenna array for DVB-T based passive bistatic radar applications

A Digital Video Broadcast Terrestrial (DVB-T) based passive radar requires the development of an antenna array that performs satisfactorily over the entire DVB-T band. The array should require no mechanical adjustments to inter-element spacing to correspond to the DVB-T carrier frequency used for any particular measurement. This paper will describe the challenges involved in designing an antenna array with a bandwidth of 450 MHz. It will discuss the design procedure and demonstrate a number of simulated array configurations. The final configuration of the array will be shown as well as simulations of the expected performance over the desired frequency span.

Design of a wideband conformal array antenna system with beamforming and null steering, for application in a DVB-T based passive radar

The use of radars in detecting low flying, small targets is being explored for several decades now. However radar with counter-stealth abilities namely the passive, multistatic, low frequency radars are in the focus recently. Passive radar that uses Digital Video Broadcast Terrestrial (DVB-T) signals as illuminator of opportunity is a major contender in this area. A DVB-T based passive radar requires the development of an antenna array that performs satisfactorily over the entire DVB-T band. At Fraunhofer FHR, there is currently a need for an array antenna to be designed for operation over the 450-900 MHz range with wideband beamforming and null steering capabilities. This would add to the ability of the passive radar in detecting covert targets and would improve the performance of the system. The array should require no mechanical adjustments to inter-element spacing to correspond to the DVB-T carrier frequency used for any particular measurement. Such an array would have an increased flexibility of operation in different environment or locations.

The design of such an array antenna and the applied techniques for wideband beamforming and null steering are presented in the thesis. The interaction between the inter-element spacing, the grating lobes and the mutual couplings had to be carefully studied and an optimal solution was to be reached at that meets all the specifications of the antenna array for wideband applications. Directional beams, nulls along interference directions, low sidelobe levels, polarization aspects and operation along a wide bandwidth of 450-900 MHz were some of the key considerations.

Integrated Low-Loss Passive SiGe Power Splitter and Combiner Operating Across 78-86 GHz Band

This paper describes the design, implementation, and characterization of a new type of passive power splitting and combining structure for use in a differential four-way power-combining amplifier operating at E-band. In order to achieve lowest insertion loss, input and output coils inductances are resonated with shunt capacitances. Simple C-L-C and L-C networks are proposed in order to compensate inductive loading due to routing line that would otherwise introduce mismatch and increase loss. Across 78-86 GHz band, measured insertion loss is about 7 dB. Measured return losses are >10 dB from 73 GHz to 94 GHz at the input port and >9 dB from 60 GHz to 94 GHz at the output port. When integrated with driver and power amplifier cells, the simulated complete circuit exhibits 18.2 dB gain and 20.3 dBm saturated output power.

Distributed passive intermodulation generation in coplanar waveguide transmission lines

A phenomenology of distributed passive intermodulation generation in coplanar waveguide transmission line is presented. The theoretical analysis is based upon the generalised nonlinear transmission line model, which accounts for the coupling of two propagating modes. The case of weak substrate nonlinearity is considered and the model is given qualitative verification through the mapping of passive intermodulation products generated in coplanar waveguide fabricated on a commercial laminate. Implications for future research are discussed. © 2012 IEEE.

An intelligent configuration-sampling based local motion planner for robotic manipulators

Manipulator motion planning is a task which relies heavily on the construction of a configuration space prior to path planning. However when fast real-time motion is needed, the full construction of the manipulator's high-dimensional configu-ration space can be too slow and expensive. Alternative planning methods, which avoid this full construction of the manipulator's configuration space are needed to solve this problem. Here, one such existing local planning method for manipulators based on configuration-sampling and subgoal-selection has been extended. Using a modified Artificial Potential Fields (APF) function, goal-configuration sampling and a novel subgoal selection method, it provides faster, more optimal paths than the previously proposed work. Simulation results show a decrease in both runtime and path lengths, along with a decrease in unexpected local minimum and crashing issues.

Potassium canrenoate treatment in paediatric patients: a population pharmacokinetic study using novel dried blood spot sampling

Objective: To characterize the population pharmacokinetics of canrenone following administration of potassium canrenoate (K-canrenoate) in paediatric patients.

Methods: Data were collected prospectively from 37 paediatric patients (median weight 2.9?kg, age range 2 days–0.85 years) who received intravenous K-canrenoate for management of retained fluids, for example in heart failure and chronic lung disease. Dried blood spot (DBS) samples (n?=?213) from these were analysed for canrenone content and the data subjected to pharmacokinetic analysis using nonlinear mixed-effects modelling. Another group of patients (n?=?16) who had 71 matching plasma and DBS samples was analysed separately to compare canrenone pharmacokinetic parameters obtained using the two different matrices.

Results: A one-compartment model best described the DBS data. Significant covariates were weight, postmenstrual age (PMA) and gestational age. The final population models for canrenone clearance (CL/F) and volume of distribution (V/F) in DBS were CL/F (l/h)?=?12.86?×? (WT/70.0)0.75?×?e [0.066?×? (PMA?-?40]) and V/F (l)?=?603.30?×? (WT/70)?×?(GA/40)1.89 where weight is in kilograms. The corresponding values of CL/F and V/F in a patient with a median weight of 2.9?kg are 1.11?l/h and 20.48?l, respectively. Estimated half-life of canrenone based on DBS concentrations was similar to that based on matched plasma concentrations (19.99 and 19.37?h, respectively, in 70?kg patient).

Conclusion: The range of estimated CL/F in DBS for the study population was 0.12–9.62?l/h; hence, bodyweight-based dosage adjustment of K-canrenoate appears necessary. However, a dosing scheme that takes into consideration both weight and age (PMA/gestational age) of paediatric patients seems more appropriate.