Inclusion of explicit thermal requirements in optimum structural design

A finite-element based procedure is described for obtaining minimum mass designs of structures subjected to combined thermal and mechanical loading and both strength and thermal constraints. The procedure is based on a mathematical programming method using the Sequence of Unconstrained Minimizations Technique (SUMT) in which design requirements are incorporated by an exterior penalty function. The procedure is limited to steady-state temperatures which are controlled by structural sizing only. The optimization procedure is demonstrated by the design of a structural wing box with both mechanical loading and external heating, subject to design constraints on stress, minimum gage, and temperature. The final design for these conditions is compared with a corresponding design in which temperature constraints are omitted

A Framework to Manage the Complex Organisation of Collaborating: Its Application to Autonomous Systems

In this paper we present an analysis of the complexities of large group collaboration and its application to develop detailed requirements for collaboration schema for Autonomous Systems (AS). These requirements flow from our development of a framework for collaboration that provides a basis for designing, supporting and managing complex collaborative systems that can be applied and tested in various real world settings. We present the concepts of "collaborative flow" and "working as one" as descriptive expressions of what good collaborative teamwork can be in such scenarios. The paper considers the application of the framework within different scenarios and discuses the utility of the framework in modelling and supporting collaboration in complex organisational structures

Cold Molecule Spectroscopy for Constraining the Evolution of the Fine Structure Constant

We report precise measurements of ground-state, $\lambda$-doublet microwave transitions in the hydroxyl radical molecule (OH). Utilizing slow, cold molecules produced by a Stark decelerator we have improved over the precision of the previous best measurement by twenty-five-fold for the F' = 2 $\to$ F = 2 transition, yielding (1 667 358 996 $\pm$ 4) Hz, and by ten-fold for the F' = 1 $\to$ F = 1 transition, yielding (1 665 401 803 $\pm$ 12) Hz. Comparing these laboratory frequencies to those from OH megamasers in interstellar space will allow a sensitivity of 1 ppm for $\Delta\alpha/\alpha$ over $\sim$$10^{10}$ years.Comment: This version corrects minor typos in the Zeeman shift discussio

Some Systematics of Galactic Globular Clusters

The global properties of all known Galactic globular clusters are examined. The relationship between the luminosities and the metallicities of Galactic globular clusters is found to be complex. Among luminous clusters there is a correlation in the sense that the oldest clusters are slightly more metal deficient than are younger clusters. However, no such clear-cut relationship is found among the faintest globular clusters. The central concentration index C of globular clusters is seen to be independent of metallicity. The dependence of the half-light radii of globular clusters on their Galactocentric distances can be approximated by the relation $R_h \alpha R^{2/3}_{gc}$. Clusters with collapsed cores are mostly situated close to the Galactic nucleus. For $R_{gc} < 10$ kpc the luminosities and the radii of clusters appear to be uncorrelated. The Galaxy differs from the LMC and the SMC in that it appears to lack highly flattened luminous clusters. Galactic globular clusters with ages $\geq$ 13.0 Gyr are all of Oosterhoff type II, whereas almost all of those with ages $<$ 13.0 Gyr have been assigned to Oosterhoff type I. Globular clusters with ages $<$11.5 Gyr are all located in the outer Galactic halo, have below-average luminosities and above-average radii. On the other hand the very old globular cluster NGC 6522 is situated close to the Galactic nucleus.Comment: PASP, in pres

An insight into some innovative cycles for aircraft propulsion

Emissions are important drivers in the design and use of aero-engines. This paper presents a part of the work carried out in the VITAL (EnVIronmenTALly aero-engine) project; it consists of a parameter study on the application of three innovative thermodynamic cycles to aircraft propulsion, looking for benefits on fuel consumption, carbon dioxide, nitrogen oxides, and noise. These cycles are intercooler-regenerative, the wave rotor topping, and the constant volume combustor cycles. The work, starting from a next-generation ultra-high bypass ratio turbofan, the baseline, and considering two possible design conditions, presents the influence of the application of these new cycles or design changes to the baseline on emissions and on the required technological level, represented by the turbine entry temperature (TET). VITAL is a project supported by the Sixth Framework Programme of the European Communities. The results showthat some significant benefits on emissions can be achieved although they are linked to significant technology improvements and in-depth studies of the new components involved in cycle implementation

Neurodevelopmental Outcomes at 2 and 3.5 Years for Very Preterm Babies Enrolled in a Randomized Trial of Milking the Umbilical Cord versus Delayed Cord Clamping

Background: Guidelines published by the International Liaison Committee for Resuscitation and by the World Health Organization recommend delaying cord clamping at birth as part of routine care for infants. Objective: To study the use of milking of the cord 4 times as an alternative to enhance the redistribution of placental blood into the baby. Methods: This is a prospective cohort study of neurodevelopmental assessment by the Bayley III method of very preterm infants who had participated in a trial of delayed cord clamping versus cord milking at birth that was conducted in a neonatal tertiary care hospital. The primary outcomes were differences in cognitive, motor and language development at 2 and 3.5 years. Two-tailed analyses were performed with the χ2 test, Fisher's exact test, t test, Mann-Whitney U test and ANCOVA. Results: Out of the 58 infants enrolled in the original study, 39 infants (67%) were assessed at 2 years and 29 (50%) at 3.5 years of age. Neurodevelopmental outcomes at 2 and 3.5 years did not significantly differ between the two groups for the three Bayley III composite scores. At 3.5 years there was a trend towards higher scores for girls in the language composite scores (girls: mean = 121.6, SD = 15.22; boys: mean = 101.07, SD = 19.84) and on the motor scale (girls: mean = 124.60, SD = 18.15; boys: mean = 97.86, SD = 17.23). Conclusions: In this small number of participants followed up at 2 and 3.5 years of age, milking of the cord 4 times did not have any long-term adverse effect on neurodevelopmental outcome, suggesting that cord milking could be used as an alternative to delayed cord clamping

Ultrasound Imaging of Gene Expression in Mammalian Cells

The study of cellular processes occurring inside intact organisms requires methods to visualize cellular functions such as gene expression in deep tissues. Ultrasound is a widely used biomedical technology enabling noninvasive imaging with high spatial and temporal resolution. However, no genetically encoded molecular reporters are available to connect ultrasound contrast to gene expression in mammalian cells. To address this limitation, we introduce mammalian acoustic reporter genes. Starting with a gene cluster derived from bacteria, we engineered a eukaryotic genetic program whose introduction into mammalian cells results in the expression of intracellular air-filled protein nanostructures called gas vesicles, which produce ultrasound contrast. Mammalian acoustic reporter genes allow cells to be visualized at volumetric densities below 0.5% and permit high-resolution imaging of gene expression in living animals

Variable Stars in the Globular Cluster M5. Application of the Image Subtraction Method

We present $V$-band light curves of 61 variables from the core of the globular cluster M5 obtained using a newly developed image subtraction method (ISM). Four of these variables were previously unknown. Only 26 variables were found in the same field using photometry obtained with DoPHOT software. Fourier parameters of the ISM light curves have relative errors up to 20 times smaller than parameters measured from DoPHOT photometry. We conclude that the new method is very promising for searching for variable stars in the cores of the globular clusters and gives very accurate relative photometry with quality comparable to photometry obtained by HST. We also show that the variable V104 is not an eclipsing star as has been suggested, but is an RRc star showing non-radial pulsations.Comment: submitted to MNRAS, 9 pages, 4 figure

Spaceborne Fiber Optic Data Bus (SFODB)

Spaceborne Fiber Optic Data Bus (SFODB) is an IEEE 1393 compliant, gigabit per second, fiber optic network specifically designed to support the real-time, on-board data handling requirements of remote sensing spacecraft. The network is fault tolerant highly reliable, and capable of withstanding the rigors of launch and the harsh space environment. SFODB achieves this operational and environmental performance while maintaining the small size, light weight, and low power necessary for spaceborne applications. On December 9, 1998, SFODB was successfully demonstrated at NASA's Goddard Space Flight Center (GSFC)