995 resultados para post-relational DBMS
Resumo:
This paper investigates the limitations of postcolonial planning practices that aimed to modernise Cairo’s urban spaces during Gamal Abdel Nasser rule (1952–70). Following the Free Officers revolution of 1952, ambition to display urban order through forceful change in the city’s built environment was in action. Nasser’s visions of modernity were explicit in a series of attempts to reshape several prime locations in central Cairo, which included the old traditional waterfront quarter, in Bulaq Abul Ela. An analysis of the Bulaq planning scheme drafted in 1966 reveals insights into how notions of order were spatialised to integrate with Cairo’s complex urban fabric. The official plans to regularise Bulaq also strongly demonstrates how this was a top-down, centralised process in terms of governance, with full utilisation of state resources, namely the military and the media. From a wider perspective, planning practices under Nasser demonstrated an evident break with the past to eliminate memories of colonisation and disorder. Drawing on original resources, archival material, meeting minutes and maps of this historical but dilapidated quarter of Cairo, this paper gives an insight into how Nasser’s government attempted to convey a sense of order in a revolutionary country without, however, having an understanding of order as a coherent, multilayered and sequential process of change.
Resumo:
As part of a programme to investigate spatial variations in the Galactic chemical composition, we have been searching for normal B-type stars and A-type supergiants near the Galactic center. During this search we have found eleven peculiar stars, and in some cases performed detailed abundance analyses of them which suggest that they may be at a post-AGB evolutionary stage.
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A post-Markovian master equation has been recently proposed as a tool to describe the evolution of a system coupled to a memory-keeping environment [A. Shabani and D. A. Lidar, Phys. Rev. A 71, 020101 ( R) ( 2005)]. For a single qubit affected by appropriately chosen environmental conditions, the corresponding dynamics is always legitimate and physical. Here we extend such a situation to the case of two qubits, only one of which experiences the environmental effects. We show how, despite the innocence of such an extension, the introduction of the second qubit should be done cum grano salis to avoid consequences such as the breaking of the positivity of the associated dynamical map. This hints at the necessity of using care when adopting phenomenologically derived models for evolutions occurring outside the Markovian framework.
Resumo:
1. Deer are of major concern with regards to impacts on biodiversity, forestry and agriculture as well as human health. The invasive Reeves’ muntjac deer Muntiacus reevesi, native to Asia but established in Great Britain, has recently appeared in the wild in Ireland. <br/><br/>2. The first verified record in the wild in Northern Ireland was confirmed during June 2009 as a result of a road traffic accident near Newtownards, Co. Down. The second record was a culled animal shot in the grounds of Mount Stewart, Co. Down during June 2011.<br/><br/>3. The current report aimed to perform a detailed investigation of the most recently obtained animal to establish a) its age, b) its genetic relationship with the first animal and c) the threat it might pose in terms of carrying endo- or ecto-parasites or other micro-pathogens, principally viruses and bacteria.<br/><br/>4. Analysis of its dentition suggested the culled animal was 56 weeks old (range 55-57 weeks).<br/><br/>5. Genetic analysis indicated that there was no possibility of a father-son relationship with the buck killed in 2009. There was a 6.25% probability of both individuals being full-sibs and a 25% probability of a half-sib relationship.<br/><br/>6. The deer was free from all the major pathogens. Most significantly, a novel species of Gammaherpesvirus was detected most closely matching type 2 ruminant rhadinovirus (Gammaherpesvirinae) from mule deer. Further sequencing is required to provide a definitive classification. There is no evidence suggesting this virus is pathogenic but its detection is nonetheless of concern. <br/><br/>7. During late 2009 (after the first animal was recovered) and early 2010, there were a number of sightings of muntjac within the vicinity of Mount Stewart. Our results indicate that the animal shot in June 2011 could not have been this same animal, as the shot animal must have been born in spring 2010. Moreover, genetic analysis indicates that the two recovered individuals were highly unlikely to share the same mother and father, suggesting they were the offspring of a minimum of three breeding adults (two fathers and one mother or two mothers and one father). This brings the total number of known individuals to 5 including the two offspring. The location of the breeding adults is unknown and may be either in captivity with subsequent escapees, or deliberate releases, or be free living in the wild. However, a further sighting during early 2012 may suggest a wild origin.
Resumo:
The development of a plasma discharge at low voltage (200-600 V) in saline solution is characterized using fast and standard CCD camera imaging. Vapor formation, plasma formation, and vapor collapse and subsequent pressure wave propagation are observed. If, with increasing voltage, the total energy deposited is kept approximately constant, the sequence and nature of events are similar but develop faster and more reproducibly at the higher voltages. This is attributed to the slower temporal evolution of the vapor layer at lower voltages which means a greater sensitivity to hydrodynamic instabilities at the vapor-liquid interface.
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In this paper we demonstrate a new concept in the production of negative hydrogen ions in a low-pressure multicusp discharge. The discharge voltage is modulated to produce a non-Maxwellian, hot-electron plasma during the current pulse, followed by a cool Maxwellian electron plasma in the post discharge. This procedure, of separating in time the required hot and cold electron plasmas required for volume H- production, is called a temporal filter. The time evolution of the electron energy distribution function is measured using the time-resolved second derivative of a Langmuir probe characteristic. Time-resolved measurements of the negative ion density are made using laser photodetachment. The measurements show that the negative ion density in the center of the source, at a gas pressure of 0.07 Pa, increases by a factor of 2 when the discharge is switched off. At this low pressure the average H- beam current extracted from the source, when operated with a discharge current of 1 A in the pulse modulated mode exceeds the H- beam current from a 5 A continuously operated source. The increase in efficiency of the pulsed source is explained in terms of a two-step H- production mechanism.
Resumo:
<p>Assembling aircraft stiffened panels using friction stir welding offers potential to reduce fabrication time in comparison to current mechanical fastener assembly, making it economically feasible to select structurally desirable stiffener pitching and novel panel configurations. With such a departure from the traditional fabrication process, much research has been conducted on producing strong reliable welds, with less examination of the impact of welding process residual effects on panel structural behaviour and the development of appropriate design methods. This article significantly expands the available panel level compressive strength knowledge, demonstrating the strength potential of a welded aircraft panel with multiple lateral and longitudinal stiffener bays. An accompanying computational study has determined the most significant process residual effects that influence panel strength and the potential extent of panel degradation. The experimental results have also been used to validate a previously published design method, suggesting accurate predictions can be made if the conventional aerospace design methods are modified to acknowledge the welding altered panel properties.</p>