Optimal box-covering algorithm for fractal dimension of complex networks

The self-similarity of complex networks is typically investigated through computational algorithms the primary task of which is to cover the structure with a minimal number of boxes. Here we introduce a box-covering algorithm that not only outperforms previous ones, but also finds optimal solutions. For the two benchmark cases tested, namely, the E. Coli and the WWW networks, our results show that the improvement can be rather substantial, reaching up to 15% in the case of the WWW network.Comment: 5 pages, 6 figure

Molecular characterization of a phytoplasma causing phyllody in clover and other herbaceous hosts in northern Italy

Red clover (Trifolium pratense) and Ladino clover (Trifolium repens) plants showing phytoplasma-associated symptoms (yellowing/reddening, virescence and phyllody) have been recovered in Friuli-Venezia Giulia, Italy. Using AluI RFLP analysis of PCR amplified 16S rDNA we showed that the disease can be caused independently by two phylogenetically distinct phytoplasmas. One of them showed the very typical 16S rDNA RFLP pattern of the agent of Clover Phyllody in Canada (CCPh). The 16S rDNA of the other phytoplasma (Italian Clover Phyllody phytoplasma, ICPhp) has been PCR amplified, cloned and sequenced. The sequence revealed high similarity (>98%) with phytoplasmas belonging to the X disease cluster, which includes organisms not reported to cause phyllody on their hosts. The analysis by AluI RFLP of the PCR amplified pathogen 16S rDNA from other herbaceous plants (Crepis biennis, Taraxacum officinale, Leucanthemum vulgare) collected nearby with phytoplasma-associated symptoms showed similar patterns. Southern blot hybridization of their EcoRI digested total DNA revealed identical RFLP patterns, suggesting that the causative agent may be the same organism

High Resolution X-Ray Micro-CT of Ultra-Thin Wall Space Components

A high resolution micro-CT system has been assembled and is being used to provide optimal characterization for ultra-thin wall space components. The Glenn Research Center NDE Sciences Team, using this CT system, has assumed the role of inspection vendor for the Advanced Stirling Convertor (ASC) project at NASA. This article will discuss many aspects of the development of the CT scanning for this type of component, including CT system overview; inspection requirements; process development, software utilized and developed to visualize, process, and analyze results; calibration sample development; results on actual samples; correlation with optical/SEM characterization; CT modeling; and development of automatic flaw recognition software. Keywords: Nondestructive Evaluation, NDE, Computed Tomography, Imaging, X-ray, Metallic Components, Thin Wall Inspectio

Physics Behind Precision

This document provides a writeup of contributions to the FCC-ee mini-workshop on "Physics behind precision" held at CERN, on 2-3 February 2016.Comment: https://indico.cern.ch/event/469561

Creep Properties of NiAl-1Hf Single Crystals Re-Investigated

NiAl-1Hf single crystals have been shown to be quite strong at 1027 C, with strength levels approaching those of advanced Ni-based superalloys. Initial testing, however, indicated that the properties might not be reproducible. Study of the 1027 C creep behavior of four different NiAl-1Hf single-crystal ingots subjected to several different heat treatments indicated that strength lies in a narrow band. Thus, we concluded that the mechanical properties are reproducible. Recent investigations of the intermetallic NiAl have confirmed that minor alloying additions combined with single-crystal growth technology can produce elevated temperature strength levels approaching those of Ni-based superalloys. For example, General Electric alloy AFN 12 {Ni-48.5(at.%) Al-0.5Hf-1Ti-0.05Ga} has a creep rupture strength equivalent to Rene 80 combined with a approximately 30-percent lower density, a fourfold improvement in thermal conductivity, and the ability to form a self-protective alumina scale in aggressive environments. Although the compositions of strong NiAl single crystals are relatively simple, the microstructures are complex and vary with the heat treatment and with small ingot-toingot variations in the alloy chemistry. In addition, initial testing suggested a strong dependence between microstructure and creep strength. If these observations were true, the ability to utilize NiAl single-crystal rotating components in turbine machinery could be severely limited. To investigate the possible limitations in the creep response of high-strength NiAl single crystals, the NASA Glenn Research Center at Lewis Field initiated an in depth investigation of the effect of heat treatment on the microstructure and subsequent 1027 C creep behavior of [001]-oriented NiAl-1Hf with a nominal chemistry of Ni-47.5Al-1Hf-0.5Si. This alloy was selected since four ingots, grown over a number of years and possessing slightly different compositions, were available for study. Specimens taken from the ingots were subjected to several heat treatment schedules, examined by transmission electron microscopy, and tested in both compression and tension. An example of the microstructure found in a [001]-oriented NiAl-1Hf specimen after a solution treatment at 1317 C for 50 hr followed by air cooling is illustrated in the image on the left, where the NiAl matrix contains a uniform distribution of nanometer-scale Gphase (Ni16Hf6Si7) precipitates. Other heat treating schedules produced microstructures with nanometer-sized G-phase cubes and plates or, in an extreme case, produced a microstructure with all the G-phase converted to Heusler (Ni2AlHf) particles. The results of 1027 C creep strength and strain rate testing are illustrated which summarizes data from tensile and compressive testing of samples cut from all four NiAl-1Hf ingots and subjected to a variety of heat treatment schedules. With one exception, all the strength values lie in a narrow band that spans six orders of magnitude in strain rate. The only factor that produced results outside of this band was the heat treatment schedule that dissolved all the G-phase and replaced it with Heusler precipitates. The results portrayed in this figure lead to the important practical conclusion that the elevated-temperature creep properties of NiAl-1Hf single crystals are reproducible and are not affected by small variations in alloy chemistry from ingot to ingot or by different initial distributions of G-phase in the heat-treated alloy. The only variable in this study that produced a significant and delerious effect on mechanical strength was a post-solution heat treatment that lead to the complete disappearance of the G-phase in favor of Heusler precipitates

Vaginal lactoferrin in prevention of preterm birth in women with bacterial vaginosis

Objective: To evaluate use of vaginal lactoferrin in prevention of preterm birth (PTB) in women with first trimester bacterial vaginosis and prior spontaneous PTB.Methods: This is a retrospective cohort study of all consecutive singleton gestations with prior PTB, and first trimester diagnosis of bacterial vaginosis. Women who were found to have bacterial vaginosis were recommended lactoferrin 300 mg vaginal tablets daily for 21 days. The primary outcome was the incidence of PTB at less than 37 weeks of gestations. Outcomes were compared in women who received daily lactoferrin with those who did notResults: During the study period, 847 pregnant women with prior spontaneous PTB were screened for bacterial vaginosis. Of them, 193 were found to have bacterial vaginosis in the first trimester, with an overall incidence of 22.8%. Out of the 193 women, 125 met the inclusion criteria for the study and were analyzed. Sixty of the included women received vaginal lactoferrin, while 65 did not. Women who received supplementation with lactoferrin had a significantly lower rate of PTB < 37 weeks (25.0 versus 44.6%; p = .02), lower mean gestational age at delivery (37.7 ± 3.2 versus 35.9 ± 4.1 weeks; p = .01), and lower rate of admission for threatened PTL (45.0 versus 70.8%; p = .04). No between-group differences were noticed in the other outcomes, including chorioamnionitis, PPROM < 34 weeks, and neonatal outcomes. No cases of late miscarriage were reported in our cohort. No cases of adverse events were reported.Conclusion: Based on this small single-center retrospective study, supplementation with vaginal lactoferrin in women with first trimester bacterial vaginosis may be an option to reduce the risk of preterm delivery

Intermediate Temperature Fluids Life Tests - Experiments

There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 725 K (170 to 450 C), including space nuclear power system radiators, fuel cells, and high temperature electronics cooling. Historically, water has been used in heat pipes at temperatures up to about 425 K (150 C). Recent life tests, updated below, demonstrate that titanium/water and Monel/water heat pipes can be used at temperatures up to 550 K (277 C), due to water's favorable transport properties. At temperatures above roughly 570 K (300 C), water is no longer a suitable fluid, due to high vapor pressure and low surface tension as the critical point is approached. At higher temperatures, another working fluid/envelope combination is required, either an organic or halide working fluid. An electromotive force method was used to predict the compatibility of halide working fluids with envelope materials. This procedure was used to reject aluminum and aluminum alloys as envelope materials, due to their high decomposition potential. Titanium and three corrosion resistant superalloys were chosen as envelope materials. Life tests were conducted with these envelopes and six different working fluids: AlBr3, GaCl3, SnCl4, TiCl4, TiBr4, and eutectic diphenyl/diphenyl oxide (Therminol VP-1/Dowtherm A). All of the life tests except for the GaCl3 are ongoing; the GaCl3 was incompatible. As the temperature approaches 725 K (450 C), cesium is a potential heat pipe working fluid. Life tests results are also presented for cesium/Monel 400 and cesium/70-30 copper/nickel heat pipes operating near 750 K (477 C). These materials are not suitable for long term operation, due to copper transport from the condenser to the evaporator

Tenascin Expression in Human Placentas during FGR Affected Pregnancies and Umbilical Doppler Velocimetry Correlation

Objective: The aim of this study was to evaluate the expression of some non collagenous extracellular matrix proteins, in particular tenascin, in human placentas of intrauterine growth restricted fetuses with abnormal umbilical Doppler velocimetry. Study Design: Study group (group A) consisted of 23 pregnant women with intrauterine growth restricted fetuses, with or without preeclampsia. Control group (group B) consisted of 10 pregnant women with appropriate fetal weight for gestational age. Placental specimens were collected from biopsies obtained after cesarean delivery. Umbilical artery Doppler velocimetry was performed within four hours from delivery in all patients. Tenascin expression was studied by immunohistochemistry and western blot techniques. Results: A difference in birth weight and placental weight was found in the two groups, being lower in the study group. Umbilical artery Doppler velocimetry showed abnormal patterns in the study group and normal findings in the control one. Tenascin was strongly expressed in placentas from growth restricted fetuses, as shown by immunohistochemistry and by RT-PCR, while it was almost absent in placentas from group B. Conclusion: A relationship between abnormal Doppler patterns and tenascin distribution in growth restricted fetuses has been observed. The presence of tenascin might be considered as a placental compensatory mechanism in FGR fetuses with abnormal umbilical artery Doppler velocimetry

Development of Wireless Techniques in Data and Power Transmission - Application for Particle Physics Detectors

Wireless techniques have developed extremely fast over the last decade and using them for data and power transmission in particle physics detectors is not science- fiction any more. During the last years several research groups have independently thought of making it a reality. Wireless techniques became a mature field for research and new developments might have impact on future particle physics experiments. The Instrumentation Frontier was set up as a part of the SnowMass 2013 Community Summer Study [1] to examine the instrumentation R&D for the particle physics research over the coming decades: {\guillemotleft} To succeed we need to make technical and scientific innovation a priority in the field {\guillemotright}. Wireless data transmission was identified as one of the innovations that could revolutionize the transmission of data out of the detector. Power delivery was another challenge mentioned in the same report. We propose a collaboration to identify the specific needs of different projects that might benefit from wireless techniques. The objective is to provide a common platform for research and development in order to optimize effectiveness and cost, with the aim of designing and testing wireless demonstrators for large instrumentation systems