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In recent years, the aviation industry has taken a leading role in the integration of composite structures to develop lighter and more fuel efficient aircraft. Among the leading concepts to achieve this goal is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. The focus of most PRSEUS studies has been on developing an hybrid wing body structure, with only a few discussing the application of PRSEUS to a tube-wing fuselage structure. Additionally, the majority of investigations for PRSEUS have focused on experimental validation of anticipated benefits rather than developing a methodology to capture the behavior of stitched structure analytically. This paper presents an overview of a numerical methodology capable of accurately describing PRSEUS’ construction and how it may be implemented in a barrel fuselage platform resorting to high-fidelity mesoscale modeling techniques. The methodology benefits from fresh user defined strategies developed in a commercially available finite element analysis environment. It further proposes a new approach for improving the ability to predict deformation in stitched composites, allowing for a better understanding of the intricate behavior and subtleties of stitched aerospace structures.
The Preceding discussions have considered the radiocarbon dates in relation to a number of archaeological, geological, and palynological problems. It remains to consider the endeavor as a whole, and to reach some conclusions concerning its present and future value and usefulness. Of primary importance is a consideration of what the dates mean. Basic to this is an understanding of the statistics involved. At the request of the Committee, Arnold, who has been intimately associated with the project, has kindly contributed the following explanatory paragraphs:
It seems worth while to review briefly the physical scientist's notions about the errors inherent in such measurements, as they apply to radiocarbon dates.
We present a multi-frequency study of the intermediate spiral SAB(r)bc type galaxy NGC 6744, using available data from the Chandra X-Ray telescope, radio continuum data from the Australia Telescope Compact Array and Murchison Widefield Array, and Wide-field Infrared Survey Explorer infrared observations. We identify 117 X-ray sources and 280 radio sources. Of these, we find nine sources in common between the X-ray and radio catalogues, one of which is a faint central black hole with a bolometric radio luminosity similar to the Milky Way’s central black hole. We classify 5 objects as supernova remnant (SNR) candidates, 2 objects as likely SNRs, 17 as H ii regions, 1 source as an AGN; the remaining 255 radio sources are categorised as background objects and one X-ray source is classified as a foreground star. We find the star-formation rate (SFR) of NGC 6744 to be in the range 2.8–4.7 M⊙~yr − 1 signifying the galaxy is still actively forming stars. The specific SFR of NGC 6744 is greater than that of late-type spirals such as the Milky Way, but considerably less that that of a typical starburst galaxy.
I review recent progress in determining the nature of the loop structures that form the coronae of solar-like stars. This progress has been driven by observational advances, in particular the new results from X-ray satellites (Chandra and XMM-Newton) and the availability of surface magnetograms from Zeeman-Doppler imaging. It is now clear that stars that are similar to the Sun in mass, but which rotate more rapidly, have a very different magnetic field structure. Their surfaces are more heavily spotted, with spots appearing at all latitudes, extending all the way up to the rotation pole. Their coronae are correspondingly much brighter in X-rays, containing plasma that is hotter and denser than on the Sun. In addition, stellar coronae can support massive co-rotating prominences out to many stellar radii. Recent efforts in modelling these magnetic structures are now bringing together both the surface magnetograms and also the coronal X-ray emission. The resulting coronal loop models show complex loop structures on all scales, with much of the X-ray emission coming from high latitudes where is does not suffer rotational self-eclipse. The observed high densities and X-ray emission measures are a natural consequence of the high magnetic flux density at the surface. The stripping of the corona due to centrifugal effects at high rotation rates can also explain the saturation and supersaturation of X-ray emission with increasing rotation rates, and the recent observation of a high rotational modulation in a supersaturated star.
Deep borehole disposal (or DBD) is now seen as a viable alternative to the (comparatively shallow) geologically repository concept for disposal of high level waste and spent nuclear fuel. Based on existing oil and geothermal well technologies, we report details of investigations into cementitious grouts as sealing/support matrices (SSMs) for waste disposal scenarios in the DBD process where temperatures at the waste package surface do not exceed ∼190ºC. Grouts based on Class G oil well cements, partially replaced with silica flour, are being developed, and the use of retarding admixtures is being investigated experimentally. Sodium gluconate appears to provide sufficient retardation and setting characteristics to be considered for this application and also provides an increase in grout fluidity. The quantity of sodium gluconate required in the grout to ensure fluidity for 4 hours at 90, 120 and 140°C is 0.05, 0.25 and 0.25 % by weight of cement respectively. A phosphonate admixture only appears to provide desirable retardation properties at 90°C. The presence of either retarder does not affect the composition of the hardened cement paste over 14 days curing and the phases formed are durable under conditions of high temperature and pressure.
Model scale tests of modern ‘open rotor’ propulsor concepts that have potential for significant fuel burn reduction for aircraft applications were completed at NASA Glenn Research Center. The recent test campaign was a collaboration between NASA, FAA, and General Electric (GE). GE was the primary industrial partner, but other organisations were involved such as Boeing and Airbus who provided additional hardware for fuselage simulations. The open rotor is a modern version of the UnDucted Fan (UDF®) that was flight tested in the late 1980s through a partnership between NASA and GE. The UDF® was memorable for its scimitar shaped propeller blades and its unique noise signature. Design methods of the time were not able to optimise for both high aerodynamic efficiency and low noise simultaneously. Contemporary CFD/CAA based design methods can produce open rotor blade designs that maintain efficiency with acceptable acoustic signatures. Tests of two generations of new open rotor designs were conducted in the 9’ × 15’ Low Speed Wind Tunnel and the 8’ × 6’ Supersonic Wind Tunnel starting in late 2009 and completed in early 2012. Aerodynamic performance and acoustic data were obtained for take-off, approach and cruise conditions in isolated and semi-installed configurations. Additional detailed flow diagnostic measurements and acoustic measurements, including canonical shielding configurations, were obtained by NASA. NASA and GE conducted joint systems analysis to evaluate the performance of the new blade designs on a Boeing 737 class aircraft. The program demonstrated a 2-3% improvement in overall net efficiency relative to the best efficiency designs of the 1980s while nominally achieving 15-17 EPNdB noise margin to Chapter 4 (at a Technology Readiness Level of 5) for a notional aircraft system defined by NASA.
The majority of extra-solar planets have been discovered (or confirmed after follow-up) through radial-velocity (RV) surveys. Using ground-based spectrographs such as High Accuracy Radial Velocity Planetary Search (HARPS) and HARPS-North, it is now possible to detect planets that are only a few times the mass of the Earth. However, the presence of dark spots on the stellar surface produces RV signals that are very similar in amplitude to those caused by orbiting low-mass planets. Disentangling these signals has thus become the biggest challenge in the detection of Earth-mass planets using RV surveys. To do so, we use the star's lightcurve to model the RV variations produced by spots. Here we present this method and show the results of its application to CoRoT-7.
We observed with HARPS, the Rossiter-McLaughlin effect for 40 of the 75 transiting hot Jupiters discovered in the Southern Hemisphere by WASP. Our observations reveal a wide distribution in orbital inclinations indicative of past dynamical interactions. Our data also demonstrate the important effect produced by tidal interactions in shaping the spin–orbit (β) angle distribution. We briefly present and interpret the data we collected in a series of graphs.
Despite US sanitation advancements, millions of waterborne disease cases occur annually, although the precise burden of disease is not well quantified. Estimating the direct healthcare cost of specific infections would be useful in prioritizing waterborne disease prevention activities. Hospitalization and outpatient visit costs per case and total US hospitalization costs for ten waterborne diseases were calculated using large healthcare claims and hospital discharge databases. The five primarily waterborne diseases in this analysis (giardiasis, cryptosporidiosis, Legionnaires' disease, otitis externa, and non-tuberculous mycobacterial infection) were responsible for over 40 000 hospitalizations at a cost of $970 million per year, including at least $430 million in hospitalization costs for Medicaid and Medicare patients. An additional 50 000 hospitalizations for campylobacteriosis, salmonellosis, shigellosis, haemolytic uraemic syndrome, and toxoplasmosis cost $860 million annually ($390 million in payments for Medicaid and Medicare patients), a portion of which can be assumed to be due to waterborne transmission.
To examine the potential to apply chemically modified surfaces in organic thin film transistors (TFT), we report the synthesis and characterization of two tailored series of oligothiophene compounds. The oligomers have thiol end groups for coupling to gold electrodes and have regio-regular alkyl substitutions corresponding to Head-Head (HH-) and Head-Tail (HT-) molecular conformations. Variations in chain length, structures and end groups have enabled a detailed study of the deposition of films from solution and the films' properties.
Visual and verbal episodic memory deficits are putative endophenotypes for schizophrenia; however, the extent of any genetic overlap of these with schizophrenia is unclear. In this study, we set out to quantify the genetic and environmental contributions to variance in visual and verbal memory performance, and to quantify their genetic relationship with schizophrenia.
We applied bivariate genetic modelling to 280 twins in a classic twin study design, including monozygotic (MZ) and dizygotic (DZ) pairs concordant and discordant for schizophrenia, and healthy control twins. We assessed episodic memory using subtests of the Wechsler Memory Scale – Revised (WMS-R).
Genetic influences (i.e. heritability) contributed significantly to variance in immediate recall of both verbal memory and visual learning, and the delayed recall of verbal and visual memory. Liability to schizophrenia was associated with memory impairment, with evidence of significant phenotypic correlations between all episodic memory measures and schizophrenia. Genetic factors were the main source of the phenotypic correlations for immediate recall of visual learning material; both immediate and delayed recall of verbal memory; and delayed recall of visual memory that, for example, shared genetic variance with schizophrenia, which accounted for 88% of the phenotypic correlation (rph=0.41) between the two.
Verbal memory and visual learning and memory are moderately heritable, share a genetic overlap with schizophrenia and are valid endophenotypes for the condition. The inclusion of these endophenotypes in genetic association studies may improve the power to detect susceptibility genes for schizophrenia.
Auditory P50 sensory gating deficits correlate with genetic risk for schizophrenia and constitute a plausible endophenotype for the disease. The well-supported role of catechol-O-methyltransferase (COMT), brain-derived neurotrophic factor (BDNF) and neuregulin 1 (NRG1) genes in neurodevelopment and cognition make a strong theoretical case for their influence on the P50 endophenotype.
The possible role of NRG1, COMT Val158Met and BDNF Val66Met gene polymorphisms on the P50 endophenotype was examined in a large sample consisting of psychotic patients, their unaffected relatives and unrelated healthy controls using linear regression analyses.
Although P50 deficits were present in patients and their unaffected relatives, there was no evidence for an association between NRG1, COMT Val158Met or BDNF Val66Met genotypes and the P50 endophenotype.
The evidence from our large study suggests that any such association between P50 indices and NRG1, COMT Val158Met or BDNF Val66Met genotypes, if present, must be very subtle.
During the 10-year period 1978–87 there were 48 outbreaks of food poisoning in Scottish hospitals affeeting a total of 2287 persons of whom 12 died. This compared with 50 outbreaks during the previous 5 years (1973–77) when over 1500 persons and 7 deaths were recorded. Although the incidence of outbreaks has decreased the average number of persons affected in outbreaks has increased. A marked reduction was seen in the incidence of outbreaks due to Clostridium perfringens, in contrast to foodborne salmonellosis which remains a problem. Thirty-four hospitals, of which 10 reported two or more outbreaks, were involved. The type of hospitals most frequently affected were general (14), psychiatric (13), geriatric (9) and hospitals for the mentally subnormal (7). Meat, including poultry meat, was incriminated in over 90% of outbreaks where a food vehicle was identified. In modern or re-equipped kitchens cooking in advance with subsequent reheating is being progressively discontinued as more food is being cooked on the day of consumption, a practice which may readily explain the decreasing incidence of outbreaks due to Cl. perfringens. Bacterial cross-contamination from poultry-meat and other raw foods, compounded by inadequate temperature control, however, continues to be a problem in some hospitals. It is too early as yet to determine whether the removal of Crown immunity will have any effect on the future incidence of hospital ‘food poisoning’.
Inverse Compton scattering is a promising method to implement a high brightness, ultra-short, energy tunable X-ray source at accelerator facilities. We have developed an inverse Compton backscattering X-ray source driven by the multi-10 TW laser installed at Daresbury. Hard X-rays, with spectral peaks ranging from 15 to 30 keV, depending on the scattering geometry, will be generated through the interaction of laser pulses with electron bunches delivered by the energy recovery linac machine, initially known as energy recovery linac prototype and subsequently renamed accelerators and lasers in combined experiments. X-ray pulses containing 9 × 107 photons per pulse will be created from head-on collisions, with a pulse duration comparable to the incoming electron bunch length. For transverse collisions 8 × 106 photons per pulse will be generated, where the laser pulse transit time defines the X-ray pulse duration. The peak spectral brightness is predicted to be ~1021 photons/(s mm2 mrad2 0.1% Δλ/λ).
From the latter 1940s until 1977, the General Electric Corporation (GE) discharged an estimated 200,000 to 1.3 million pounds (U.S. Environmental Protection Agency, 2000a) of polychlorinated biphenyls (PCBs) into the Hudson River from two electrical capacitor manufacturing plants at Hudson Falls and Fort Edward, New York (Fig. 24.1). In 1977, under a settlement agreement with the New York State Department of Environmental Conservation, GE stopped direct discharges of PCBs to the river, although leakage of PCBs from the factory sites to the river continues to this day. PCBs used at the GE plants were oily liquids containing dozens of distinct PCB compounds. Most of these components are persistent in the environment, attach strongly to soils and river sediments, and readily accumulate in fish, wildlife, and humans (National Research Council, 2001a). These properties, combined with the large discharges of PCBs from the GE plants over 50+ years, have led to elevated levels of PCBs in the water, sediments, and biota of the Upper Hudson River (defined here as the stretch upstream of the Troy lock and dam). Levels of PCBs in the Hudson River ecosystem are among the highest in the United States.
PCB contamination in the Hudson River is a management problem for the public because it has likely increased human health risks (primarily from consumption of fish), increased ecological risks to fish and fish-eating birds and mammals, and caused losses of river use and the resulting economic impacts (catch and release only fishery; advisories on fish consumption; restrictions on navigational dredging limiting access to the Champlain Canal; restrictions on and the increased costs of dredging; and commercial fishery closure).
Señor Pinto will assume the reins of government at a peculiarly critical moment in the history of his country, a time of severe commercial depression, and when several social and financial questions press for a prompt resolution, and with the prestige of the previous administration to rival. The country will expect much from him – more, probably, than will be realized….
– The Chilian Times, September 2, 1876
The fates were not at all kind to President Pinto. During his first months in office, the world price for copper fell by 20 percent and Chilean copper exports by 16 percent: the drop for semi-smelted metal was as much as 50 percent. Silver exports remained at barely one-third of their 1874 level. Unfortunately the climate also turned belligerent: between 1876 and 1878, the country's croplands underwent months of drought punctuated by indecently generous rainfall. In 1877 a sudden trebling of precipitation washed away roads, submerged rail lines, and destroyed livestock and crops. By 1878, exports of wheat and flour had dropped by well over one-third since 1873. Approximately 300,000 laborers were thrown out of work, the pace of business slowed, and the price of food soared.
Since Chileans were unable (like the Americans and British of the 1980s and 1990s) to curb their appetite for imported goods, the trade deficit widened, and in consequence specie had to be exported in record quantities.
… a New World country with the social organization of old Spain, a twentieth-century people still preserving a feudal society; a republic based on the equality of man, yet with a blue-blood aristocracy and a servile class as distinctly separated as in any of the monarchies of the Old World. Throughout Chile's history this situation has existed. It is this social heritage that forms the background for the present-day problems of the Chilean people.
– George McBride (1936)
Underlying the competition of the parties during the Radical presidencies, and those of Ibáñez and the second Alessandri, there was the whole issue of economic development, as we now call it. The Chilean population was growing, and Chileans were no longer willing to accept the limited horizons of their parents and grandparents. They needed to find a place in Chile, or face the prospect of emigration – like those thousands who had earlier departed for the guaneras of Bolivia, the railroads of Peru, the pampas of Argentina, or M. de Lesseps's Panama Canal. They were as affected as anyone else by the twentieth-century “revolution of rising expectations,” aspiring to share the lifestyles enjoyed by other peoples -not least as images of the “developed” world reached them through the movies. Hollywood, as was often been remarked, was one of the true revolutionary forces of the twentieth century.
For this second edition of the book originally entitled A History of Chile 1808–1994 (Cambridge, 1996), we have added a new final chapter, to take account of developments since 1990 in a broad sweep, and we have made some minor revisions to the rest of the text to correct a few factual errors and to update the story. Our aim in this book is to present a general account of Chile's history as an independent nation-state for English-language readers, although we hope that Chileans, too, will enjoy it. It is our firm belief that the main task of writing Chilean history belongs to Chileans. Yet we also believe that a fresh eye can sometimes be cast over the changing Chilean scene from outside, and hopefully our effort has been worthwhile. As foreigners, we can never claim the intimate knowledge of Chilean society and culture that Chileans themselves grow up with, but we have both had a long personal connection with the country, going back to the presidency of the unforgettable Jorge Alessandri, and this book expresses, we trust, our strong affection for Chile and the Chileans. We have both enormously enjoyed Chile's undoubted charm, its scenery, its literature, its music, its people's notable humor, and, not least, its admirable wines – the finest, our upper nasal cavities tell us, in the Americas. Our lives have been enriched and sometimes frustrated by Chilean virtues and failings. We hope that something of this is communicated to the reader.
The coalition that assumed power in March 1990 would elect two further presidents over the next decade: the Christian Democrat Eduardo Frei, and, following him, the Socialist Ricardo Lagos. While these Concertación governments had to operate within the constraints inherited from the Pinochet regime (the 1980 constitution and the economic “model”), they strove very hard to modify its legacies. The first Concertación president, the septuagenarian Patricio Aylwin, was the first in Chile's history to have an English surname – an ancient one, with the prime meaning of “friend of the elves,” or the subsidiary meaning of “good friend.” The elves, albeit creatures of Nordic rather than Latin mythology, may possibly have given him some help. It is tempting to compare him, despite definite differences of demeanor, with the emollient nineteenth-century president José Joaquín Pérez. His task was in some ways similar, in some ways more daunting. Aylwin's clear head, his patience, his negotiating talent, his mildly ironic smile – these assets were invaluable to the country as it took its first steps back to what Aylwin himself, in his moving televised address on New Year's Eve 1990, termed Chile's “re-encounter” with its history.