Mapping Australia’s economy: cities as engines of prosperity

This report maps the Australian economy by the location of economic activity, defined as the dollar value of goods and services produced by workers within a particular area. Overview Eighty per cent of the value of all goods and services produced in Australia is generated on just 0.2 per cent of the nation’s land mass – mostly in cities. Today, cities are the engines of economic prosperity. But the concentration of highly productive activity in city centres presents challenges for policymakers. Too many workers live too far away to fulfil our cities’ economic potential. This report maps the Australian economy by the location of economic activity, defined as the dollar value of goods and services produced by workers within a particular area. It finds that economic activity is concentrated most heavily in the central business districts (CBDs) and inner areas of large cities. The CBDs of Sydney and Melbourne – just 7.1 square kilometres in total – generated $118 billion in 2011-12, almost 10 per cent of all economic activity in Australia, and triple the contribution of the entire agriculture sector. The intense economic contribution of CBDs occurs partly because of the concentration of jobs in these areas. But CBD businesses are also much more productive on average than those in other areas. Inner city areas and secondary commercial hubs, such as those around large cities’ airports, also tend to be more productive than other locations. For example, in 2011-12 the Sydney CBD produced$64.1 billion worth of goods and services: about $100 for every hour worked there. Employing only 13 per cent of Sydney’s workforce, this small area generates almost a quarter of the value of the Greater Sydney economy. Parramatta, often said to be Sydney’s second CBD, generated only$68 for each hour worked, and its total of $6.8 billion was about a tenth of the value generated in the CBD. There is a reason intense economic activity is concentrating in CBDs and inner suburbs. Many businesses in these areas provide highly knowledge-intensive and specialised services such as funds management, insurance, design, engineering and international education. These businesses depend on highly skilled workers, and locating in the heart of large cities gives them access to the largest possible pools of them. Proximity to suppliers, customers and partners also helps businesses to work efficiently, to generate opportunities and to come up with new ideas and ways of working. Knowledge-intensive activity is present in all sectors, including manufacturing and mining. Perth’s CBD is home to more than a third of Western Australian mining jobs, including accountants, administrators, geologists and specialist engineers. In the early 20th century one in three workers were employed in primary industry and almost half of the population lived on rural properties or in towns of less than 3,000 people. By 1960 manufacturing had grown to make up almost 30 per cent of GDP and employ one in four Australians, with a big presence in suburban areas. But today the small areas that generate most value are often a very long commute from the fast-growing outer suburbs in which many Australians live. If the prosperity that comes from knowledge-intensive activity is to be widely shared, governments need to enable more people to live closer to these areas, and to improve road and public transport networks so that they better connect employers and workers

Cluster Randomised Trials in Cochrane Reviews: Evaluation of Methodological and Reporting Practice

Objective Systematic reviews can include cluster-randomised controlled trials (C-RCTs), which require different analysis compared with standard individual-randomised controlled trials. However, it is not known whether review authors follow the methodological and reporting guidance when including these trials. The aim of this study was to assess the methodological and reporting practice of Cochrane reviews that included C-RCTs against criteria developed from existing guidance. Methods Criteria were developed, based on methodological literature and personal experience supervising review production and quality. Criteria were grouped into four themes: identifying, reporting, assessing risk of bias, and analysing C-RCTs. The Cochrane Database of Systematic Reviews was searched (2nd December 2013), and the 50 most recent reviews that included C-RCTs were retrieved. Each review was then assessed using the criteria. Results The 50 reviews we identified were published by 26 Cochrane Review Groups between June 2013 and November 2013. For identifying C-RCTs, only 56% identified that C-RCTs were eligible for inclusion in the review in the eligibility criteria. For reporting C-RCTs, only eight (24%) of the 33 reviews reported the method of cluster adjustment for their included C-RCTs. For assessing risk of bias, only one review assessed all five C-RCT-specific risk-of-bias criteria. For analysing C-RCTs, of the 27 reviews that presented unadjusted data, only nine (33%) provided a warning that confidence intervals may be artificially narrow. Of the 34 reviews that reported data from unadjusted C-RCTs, only 13 (38%) excluded the unadjusted results from the meta-analyses. Conclusions The methodological and reporting practices in Cochrane reviews incorporating C-RCTs could be greatly improved, particularly with regard to analyses. Criteria developed as part of the current study could be used by review authors or editors to identify errors and improve the quality of published systematic reviews incorporating C-RCTs

There are many ways to spin a photon : half-quantization of a total optical angular momentum

This work was supported by the Higher Education Authority of Ireland under PRTLI (Programme for Research in Third-Level Institutions) funding cycle 5 and by Science Foundation Ireland (09/SIRG/I1592, 12/RC/2278).The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ. We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization.Publisher PDFPeer reviewe

High-speed chromatic dispersion monitoring of a two-channel WDM system using a single TPA microcavity

Chromatic dispersion monitoring of two 160 Gb/s wavelength channels using a TPA Microcavity is presented. As the microcavity exhibits a wavelength resonance characteristic, a single device could monitor a number of different WDM-channels sequentially

Wavelength tuneable pulse monitoring using a Two-Photon-Absorption microcavity

Two Photon Absorption (TPA) is a non-linear optical-to-electrical conversion process that can be significantly enhanced by placing the active region within a resonance microcavity. The experiment confirmed the potential use of the microcavity structure for monitoring a single channel in multi-wavelength systems. The cavity can be designed for different applications depending on desired resonance width or cavity life time allowing the contrast ratio to be further improved. Due to the possibility of tuning the resonance wavelength by cavity tilting, a single device can be used to monitor a number of WDM channels without the need for additional optical filters

Resonance tuning of two-photon absorption microcavities for wavelength-selective pulse monitoring

We show the potential use of a single photodetector for multichannel pulse monitoring. Two-photon absorption in a microcavity structure is used as the nonlinear optical technique for pulse monitoring. Angle tuning of the device allows the resonance to be tuned. For the device studied here that is optimized for 2-ps pulses, a possible tuning range of 55 nm is shown

Optical signal processing via two-photon absorption in a semiconductor microcavity for the next generation of high-speed optical communications network

Due to the introduction of new broadband services, individual line data rates are expected to exceed 100 Gb/s in the near future. To operate at these high speeds, new optical signal processing techniques will have to be developed. This paper will demonstrate that two-photon absorption in a specially designed semiconductor microcavity is an ideal candidate for optical signal processing applications such as autocorrelation, sampling, and demultiplexing in high-speed wavelength-division-multiplexed (WDM) and hybrid WDM/optical time-division-multiplexed networks

Chromatic dispersion monitoring for high-speed WDM systems using two-photon absorption in a semiconductor microcavity

This paper presents a theoretical and experimental investigation into the use of a two-photon absorption (TPA) photodetector for use in chromatic dispersion (CD) monitoring in high-speed, WDM network. In order to overcome the inefficiency associated with the nonlinear optical-to-electrical TPA process, a microcavity structure is employed. An interesting feature of such a solution is the fact that the microcavity enhances only a narrow wavelength range determined by device design and angle at which the signal enters the device. Thus, a single device can be used to monitor a number of different wavelength channels without the need for additional external filters. When using a nonlinear photodetector, the photocurrent generated for Gaussian pulses is inversely related to the pulsewidth. However, when using a microcavity structure, the cavity bandwidth also needs to be considered, as does the shape of the optical pulses incident on the device. Simulation results are presented for a variety of cavity bandwidths, pulse shapes and durations, and spacing between adjacent wavelength channels. These results are verified experimental using a microcavity with a bandwidth of 260 GHz (2.1 nm) at normal incident angle, with the incident signal comprising of two wavelength channels separated by 1.25 THz (10 nm), each operating at an aggregate data rate of 160 Gb/s. The results demonstrate the applicability of the presented technique to monitor accumulated dispersion fluctuations in a range of 3 ps/nm for 160 Gb/s RZ data channel

Chromatic dispersion monitoring of 80-Gb/s OTDM data signal via two-photon absorption in a semiconductor microcavity

In this letter, a novel method of chromatic dispersion monitoring via two-photon absorption (TPA) is investigated. A specially designed semiconductor microcavity is employed as a TPA detector for monitoring data signals operating at rates up to 80Gb/s. As the microcavity has a wavelength-dependent response, a single device can be used to monitor multiple channels in a multiwavelength optical telecommunication syste