Ballistic effectiveness of Zr-containing composite solid propellants as a function of binder nature and mass fraction

This paper considers the effects of binder mass fraction on the properties of energetic formulations based on zirconium and zirconium hydride. These ingredients, replacing aluminum in solid rocket motors with low vehicle performance coefficient, may increase the propellant ballistic effectiveness, thanks to the resulting higher density and notwithstanding their lower specific impulse. The propellant ballistic effectiveness is estimated via the vehicle velocity achieved using the propellant under analysis in a real vehicle. For each specific mission, the binder content can be varied to provide the optimal relationship between energetic and physical-mechanical properties, that is, one may sacrifice energy in favor of rheological and physicomechanical properties (increasing binder mass fraction), or vice versa

How and when do big data investments pay off? The role of marketing affordances and service innovation

Big data technologies and analytics enable new digital services and are often associated with superior performance. However, firms investing in big data often fail to attain those advantages. To answer the questions of how and when big data pay off, marketing scholars need new theoretical approaches and empirical tools that account for the digitized world. Building on affordance theory, the authors develop a novel, conceptually rigorous, and practice-oriented framework of the impact of big data investments on service innovation and performance. Affordances represent action possibilities, namely what individuals or organizations with certain goals and capabilities can do with a technology. The authors conceptualize and operationalize three important big data marketing affordances: customer behavior pattern spotting, real-time market responsiveness, and data-driven market ambidexterity. The empirical analysis establishes construct validity and offers a preliminary nomological test of direct, indirect, and conditional effects of big data marketing affordances on perceived big data performance

Maternal vitamin A supplementation increases natural antibody concentrations of preadolescent offspring in rural Nepal

AbstractObjectiveB1a lymphocytes—which constitutively produce most natural antibodies (NAb)—arise from an early wave of progenitors unique to fetal life. Vitamin A regulates early lymphopoiesis. In animals, deficiency during this critical period compromises B1 cell populations. The aim of this study was to investigate the effect of maternal supplementation with vitamin A or β-carotene from preconception through lactation on NAb concentrations of offspring.MethodsParticipants (N = 290) were born to participants of a cluster-randomized, placebo-controlled trial of weekly maternal vitamin A or β-carotene supplementation (7000 μg retinol equivalents) conducted in Sarlahi, Nepal (1994–1997) and assessed at ages 9 to 13 y (2006–2008). Serum retinol was measured by reversed-phase high-performance liquid chromatography at mid-pregnancy and 3 mo of age. Enzyme-linked immunosorbent assay (ELISA) was used to measure children's plasma NAb concentrations at 9 to 13 y.ResultsUnadjusted geometric mean concentrations were 20.08 U/mL (95% confidence interval [CI], 17.82–22.64) in the vitamin A group compared with 17.64 U/mL (95% CI, 15.70–19.81) and 15.96 U/mL (95% CI, 13.43–18.96) in the β-carotene and placebo groups (P = 0.07), respectively. After adjustment, maternal vitamin A supplementation was associated with a 0.39 SD increase in NAb concentrations (P = 0.02). The effect was mediated by infant serum retinol in our statistical models. Although girls had 1.4-fold higher NAb concentrations (P < 0.001), sex did not modify the vitamin A effect.ConclusionsIn an undernourished population, maternal vitamin A supplementation enhanced NAb concentrations of preadolescent children. We posit that this was due to a greater allotment of B1a precursors during fetal life and a sustained higher count of NAb-secreting B1a cells

Radiation Tolerant 3D Laser Scanner for Structural Inspections in Nuclear Reactor Vessels and Fuel Storage Pools

Accurate and timely assessment of displacements and/or structural damages in nuclear reactor vessels' components is a key action in routine inspections for planning maintenance and repairs but also in emergency situations for mitigating consequences of nuclear incidents. Nevertheless, all these components are maintained underwater and reside in high-radiation fields thus imposing harsh operative conditions to inspection devices which must cope with effects such as Cerenkov radiation background, Total Ionizing Radiation (TID), and occlusions in the detectors' field of view. To date, ultrasonic techniques and video cameras are in use for inspection of components' integrity and with measurements of volumetric and surface crack opening displacements, respectively. The present work reports the realization of a radiation tolerant laser scanner and the results of tests in a nuclear research reactor vessel for acquisition of 3D models of critical components. The device, qualified for underwater operation and for withstanding up to 1 MGy of TID, is based on a 515 nm laser diode and a fast-scanning electro-optic unit. To evaluate performances in a significant but controlled environment, the device has been deployed in the vessel of a research reactor operated by ENEA in the Casaccia Research Centre in Rome (Italy). A 3D model of the fuel rods assembly through a cooling water column of 7 m has been acquired. The system includes proprietary postprocessing software that automatically recognizes components of interest and provides dimensional analysis. Possible application fields of the system stretch to dimensional analysis also in spent nuclear fuel storage pools

When does customer-oriented leadership pay off? An investigation of frontstage and backstage service teams

The service literature highlights the importance of organizational leaders in creating an organization-wide customer orientation (CO). Yet some open questions remain regarding this relationship: Are organizational leaders from different hierarchical levels equally effective in creating a CO? Does the functional role of employees affect the importance of certain leaders? More generally, when does customer-oriented leadership really pay off? To address these questions, we investigate how senior managers’ and direct supervisors’ CO affects the CO climate and effectiveness of both frontstage and backstage service teams. Analyzing multisource data from 575 employees and their supervisors from 110 teams in a retail bank, we find that the effect of perceived senior manager CO on team CO climate and team effectiveness is stronger in backstage teams while perceived direct supervisor CO has a greater influence in frontstage teams. Moreover, team CO climate consensus moderates the effect of team CO climate on team effectiveness. These results suggest that, contrary to past theorizing, customer-oriented leadership does not per se increase team CO climate and team effectiveness; rather, the correct coupling of leadership source and degree of customer contact needs to be achieved. Service managers should use these findings and appoint the correct leader to implement CO, to make the organization-wide CO diffusion more efficient and effective

Towards a Radio-guided Surgery with β−\beta^{-} Decays: Uptake of a somatostatin analogue (DOTATOC) in Meningioma and High Grade Glioma

A novel radio guided surgery (RGS) technique for cerebral tumors using $\beta^{-}$ radiation is being developed. Checking the availability of a radio-tracer that can deliver a $\beta^{-}$ emitter to the tumor is a fundamental step in the deployment of such technique. This paper reports a study of the uptake of 90Y labeled (DOTATOC) in the meningioma and the high grade glioma (HGG) and a feasibility study of the RGS technique in these cases.Comment: 21 pages, 5 figure