Multi-kilowatt modularized spacecraft power processing system development

A review of existing information pertaining to spacecraft power processing systems and equipment was accomplished with a view towards applicability to the modularization of multi-kilowatt power processors. Power requirements for future spacecraft were determined from the NASA mission model-shuttle systems payload data study which provided the limits for modular power equipment capabilities. Three power processing systems were compared to evaluation criteria to select the system best suited for modularity. The shunt regulated direct energy transfer system was selected by this analysis for a conceptual design effort which produced equipment specifications, schematics, envelope drawings, and power module configurations

The addition of a goal-based motivational interview to treatment as usual to enhance engagement and reduce dropouts in a personality disorder treatment service: results of a feasibility study for a randomized controlled trial

Background: There are high rates of treatment non-completion for personality disorder and those who do not complete treatment have poorer outcomes. A goal-based motivational interview may increase service users’ readiness to engage with therapy and so enhance treatment retention. We conducted a feasibility study to inform the design of a randomized controlled trial. The aims were to test the feasibility of recruitment, randomization and follow-up, and to conduct a preliminary evaluation of the effectiveness of the motivational interview. Methods: Patients in an outpatient personality disorder service were randomized to receive the Personal Concerns Inventory plus treatment as usual or treatment as usual only. The main randomized controlled trial feasibility criteria were recruitment of 54% of referrals, and 80% of clients and therapists finding the intervention acceptable. Information was collected on treatment attendance, the clarity of therapy goals and treatment engagement. Results: The recruitment rate was 29% (76 of 258). Of 12 interviewed at follow-up, eight (67%) were positive about the Personal Concerns Inventory. Pre-intervention interviews were conducted with 61% (23 out of 38) of the Personal Concerns Inventory group and 74% (28 out of 38) of the treatment as usual group. Participants’ therapy goals were blind-rated for clarity on a scale of 0 to 10. The mean score for the Personal Concerns Inventory group was 6.64 (SD = 2.28) and for the treatment as usual group 2.94 (SD = 1.71). Over 12 weeks, the median percentage session attendance was 83.33% for the Personal Concerns Inventory group (N = 17) and 66.67% for the treatment as usual group (N = 24). Of 59 eligible participants at follow-up, the Treatment Engagement Rating scale was completed for 40 (68%). The mean Treatment Engagement Rating scale score for the Personal Concerns Inventory group was 6.64 (SD = 2.28) and for the treatment as usual group 2.94 (SD = 1.71). Of the 76 participants, 63 (83%) completed the Client Service Receipt Inventory at baseline and 34 of 59 (58%) at follow-up. Conclusion: Shortfalls in recruitment and follow-up data collection were explained by major changes to the service. However, evidence of a substantial positive impact of the Personal Concerns Inventory on treatment attendance, clarity of therapy goals and treatment engagement, make a full-scale evaluation worth pursuing. Further preparatory work is required for a multisite trial

Photon echo quantum memories in inhomogeneously broadened two level atoms

Here we propose a solid-state quantum memory that does not require spectral holeburning, instead using strong rephasing pulses like traditional photon echo techniques. The memory uses external broadening fields to reduce the optical depth and so switch off the collective atom-light interaction when desired. The proposed memory should allow operation with reasonable efficiency in a much broader range of material systems, for instance Er3+ doped crystals which have a transition at 1.5 um. We present analytic theory supported by numerical calculations and initial experiments.Comment: 7 pages, 8 figure

Colloidal ionic complexes on periodic substrates: ground state configurations and pattern switching

We theoretically and numerically studied ordering of "colloidal ionic clusters" on periodic substrate potentials as those generated by optical trapping. Each cluster consists of three charged spherical colloids: two negatively and one positively charged. The substrate is a square or rectangular array of traps, each confining one such cluster. By varying the lattice constant from large to small, the observed clusters are first rod-like and form ferro- and antiferro-like phases, then they bend into a banana-like shape and finally condense into a percolated structure. Remarkably, in a broad parameter range between single-cluster and percolated structures, we have found stable supercomplexes composed of six colloids forming grape-like or rocket-like structures. We investigated the possibility of macroscopic pattern switching by applying external electrical fields.Comment: 14 pages, 13 figure

Feature weighting techniques for CBR in software effort estimation studies: A review and empirical evaluation

Context : Software effort estimation is one of the most important activities in the software development process. Unfortunately, estimates are often substantially wrong. Numerous estimation methods have been proposed including Case-based Reasoning (CBR). In order to improve CBR estimation accuracy, many researchers have proposed feature weighting techniques (FWT). Objective: Our purpose is to systematically review the empirical evidence to determine whether FWT leads to improved predictions. In addition we evaluate these techniques from the perspectives of (i) approach (ii) strengths and weaknesses (iii) performance and (iv) experimental evaluation approach including the data sets used. Method: We conducted a systematic literature review of published, refereed primary studies on FWT (2000-2014). Results: We identified 19 relevant primary studies. These reported a range of different techniques. 17 out of 19 make benchmark comparisons with standard CBR and 16 out of 17 studies report improved accuracy. Using a one-sample sign test this positive impact is significant (p = 0:0003). Conclusion: The actionable conclusion from this study is that our review of all relevant empirical evidence supports the use of FWTs and we recommend that researchers and practitioners give serious consideration to their adoption

Sending children to school: rural livelihoods and parental investment in education in northern Tanzania

Evolutionary and economic models of the demographic transition argue that economic development incentivizes low-fertility, high-investment parental strategies, and that such strategies emerge first in relatively wealthy families within populations undergoing 'modernization'. However, most research focuses on fertility reduction rather than shifting parental investment, and few studies consider how parental decisions regarding educational investment vary in relation to alternative rural livelihoods. Using data from 19 villages and 1,719 children (7-19 years), we investigate the effects of diversifying livelihoods, wealth and child characteristics on multiple measures of educational investment in rural Tanzania. Children in (predominantly Maasai) pastoralist households were the least likely to attend school, while neighboring farmers and business owners invested more in education. Household wealth, as measured by asset ownership, was also independently positively associated with educational investment for all livelihood types. These results are consistent with lower opportunity costs and greater perceived economic pay-offs to education for relatively labor market-integrated and wealthy households. However, among pastoralists wealth held in livestock was not associated with educational investment This result may reflect elevated opportunity costs related to the child labor demands of livestock herding. We find a marginal female advantage in education, which is surprising because qualitative research and numerous development projects in the region emphasize the disadvantages facing girls. We also find suggestive evidence of a later-born disadvantage (i.e. borderline statistically significant) consistent with the predicted consequences of sequential household resource dilution. Female advantage and later-born disadvantage were particularly evident in the wealthiest households. Greater reliability in the returns to education for wealthy households may favor preferential treatment of children with higher perceived long-term payoffs, while equal but lower-level investment in all children in relatively poor families may reflect a bet-hedging strategy. We discuss our results in light of parental investment theory and the wider literature on the demographic transition. (C) 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Estimating the retrotransposition rate of human Alu elements

Mobile elements such as Alu repeats have substantially altered the architecture of the human genome, and de novo mobile element insertions sometimes cause genetic disorders. Previous estimates for the retrotransposition rate (RR) of Alu elements in humans of one new insertion every ∼100-125 births were developed prior to the sequencing of the human and chimpanzee genomes. Here, we used two independent methods (based on the new genomic data and on disease-causing de novo Alu insertions) to generate refined Alu RR estimates in humans. Both methods consistently yielded RR on the order of one new Alu insertion every ∼20 births, despite the fact that the evolutionary-based method represents an average RR over the past ∼6 million years while the mutation-based method better reflects the current-day RR. These results suggest that Alu elements retrotranspose at a faster rate in humans than previously thought, and support the potential of Alu elements as mutagenic factors in the human genome. © 2006 Elsevier B.V. All rights reserved

Average of trial peaks versus peak of average profile : impact on change of direction biomechanics

The aims of this study were twofold: firstly, to compare lower limb kinematic and kinetic variables during a sprint and 90° cutting task between two averaging methods of obtaining discrete data (peak of average profile vs. average of individual trial peaks); secondly, to determine the effect of averaging methods on participant ranking of each variable within a group. Twenty-two participants, from multiple sports, performed a 90° cut, whereby lower limb kinematics and kinetics were assessed via 3D motion and ground reaction force (GRF) analysis. Six of the eight dependent variables (vertical and horizontal GRF; hip flexor, knee flexor, and knee abduction moments, and knee abduction angle) were significantly greater (p ≤ 0.001, g = 0.10-0.37, 2.74-10.40%) when expressed as an average of trial peaks compared to peak of average profiles. Trivial (g ≤ 0.04) and minimal differences (≤ 0.94%) were observed in peak hip and knee flexion angle between averaging methods. Very strong correlations (ρ ≥ 0.901, p <0.001) were observed for rankings of participants between averaging methods for all variables. Practitioners and researchers should obtain discrete data based on the average of trial peaks because it is not influenced by misalignments and variations in trial peak locations, in contrast to the peak from average profile