A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment

A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies

X-ray Emission from the 3C 273 Jet

We present results from four recent Chandra monitoring observations of the jet in 3C 273 using the ACIS detector, obtained between November 2003 and July 2004. We find that the X-ray emission comes in two components: unresolved knots that are smaller than the corresponding optically emitting knots and a broad channel that is about the same width as the optical interknot region. We compute the jet speed under the assumption that the X-ray emission is due to inverse Compton scattering of the cosmic microwave background, finding that the dimming of the jet X-ray emission to the jet termination relative to the radio emission may be due to bulk deceleration.Comment: 2 pages, 2 figures, to appear in the proceedings of "The X-ray Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200

Ten Economic Facts About Crime and Incarceration in the United States

Crime and high rates of incarceration impose tremendous costs on society, with lasting negative effects on individuals, families, and communities. Rates of crime in the United States have been falling steadily, but still constitute a serious economic and social challenge. At the same time, the incarceration rate in the United States is so high -- more than 700 out of every 100,000 people are incarcerated -- that both crime scholars and policymakers alike question whether, for nonviolent criminals in particular, the social costs of incarceration exceed the social benefits

On the absence of Shapiro-like steps in certain mesoscopic S-N-S junctions

In DC transport through mesoscopic S-N-S junctions, it is known that the Josephson coupling decreases exponentially with increasing temperature, but the phase dependence of the conductance persists to much higher temperatures and decreases only as 1/T. It is pointed out here that, despite the fact that such a phase-dependent conductance does bring about an AC current for a pure DC voltage, it cannot, by itself, lead to the formation of Shapiro steps.Comment: 1 page, to be published in PRL (as Comment

Would Hegel Be A ‘Hegelian' Today?

In this paper H. S. Harris argues that it is misguided to suggest that Hegelrsquo;s philosophical project was a dialectical illusion generated by his historical situation and that he would never have believed that his vision was achievable if he had been faced with the world that we face today. Not only does Harris proclaim himself to be a Hegelian, he claims that Hegel would today also remain a Hegelian. He goes on to argue that despite the fragmentation of the twentieth century and the apparent collapse of the vision articulated in the French Revolution, Hegelrsquo;s thinking continues to be relevant because although his philosophy is the lsquo;comprehension of onersquo;s timersquo;, Hegel also produces a philosophy that is out of time and somehow final.br

Symmetric photon-photon coupling by atoms with Zeeman-split sublevels

We propose a simple scheme for highly efficient nonlinear interaction between two weak optical fields. The scheme is based on the attainment of electromagnetically induced transparency simultaneously for both fields via transitions between magnetically split F=1 atomic sublevels, in the presence of two driving fields. Thereby, equal slow group velocities and symmetric cross-coupling of the weak fields over long distances are achieved. By simply tuning the fields, this scheme can either yield giant cross-phase modulation or ultrasensitive two-photon switching.Comment: Modified scheme, 4 pages, 1 figur

A solvable non-conservative model of Self-Organized Criticality

We present the first solvable non-conservative sandpile-like critical model of Self-Organized Criticality (SOC), and thereby substantiate the suggestion by Vespignani and Zapperi [A. Vespignani and S. Zapperi, Phys. Rev. E 57, 6345 (1998)] that a lack of conservation in the microscopic dynamics of an SOC-model can be compensated by introducing an external drive and thereby re-establishing criticality. The model shown is critical for all values of the conservation parameter. The analytical derivation follows the lines of Broeker and Grassberger [H.-M. Broeker and P. Grassberger, Phys. Rev. E 56, 3944 (1997)] and is supported by numerical simulation. In the limit of vanishing conservation the Random Neighbor Forest Fire Model (R-FFM) is recovered.Comment: 4 pages in RevTeX format (2 Figures) submitted to PR

Field correlations and effective two level atom-cavity systems

We analyse the properties of the second order correlation functions of the electromagnetic field in atom-cavity systems that approximate two-level systems. It is shown that a recently-developed polariton formalism can be used to account for all the properties of the correlations, if the analysis is extended to include two manifolds - corresponding to the ground state and the states excited by a single photon - rather than just two levels.Comment: 4 pages, 2 figures, published versio

Studi Pemanfaatan Limbah Padat Dari Perkebunan Kelapa Sawit Pada PLTU 6 MW Di Bangka Belitung

Limbah padat dari perkebunan kelapa sawit berupa cangkang dan fibre dapat dimanfaatkan sebagai sumber energi alternatif pada PLTU. Cangkang memiliki kandungan energi sebesar 4115 kkal/kg dan fibre sebesar 3500 kkal/kg. Cangkang dan fibre dimanfaatkan sebagai bahan bakar pada PLTU 6 MW, yang digunakan untuk memanaskan air didalam boiler sehingga menghasilkan temperatur uap dan tekanan uap yang mampu memutar turbin uap. Turbin uap berfungsi sebagai prime mover untuk memutar generator sehingga menghasilkan output berupa daya listrik. Pada saat menggunakan bahan bakar cangkang PLTU 6 MW menghasilkan ouput rata – rata sebesar 4.8 MW/hr dan dalam 1 MW output membutuhkan 1.02 ton cangkang dan pada saat menggunakan bahan bakar fibre PLTU 6 MW menghasilkan output rata – rata 2.3 MW/hr dan dalam 1 MW output membutuhkan 1.83 ton fibre. Karena lebih optimal dalam pengoperasian serta maksimalnya output yang dihasilkan dari bahan bakar cangkang, maka efisiensinya pun lebih baik. Efisiensi PLTU 6 MW pada saat menggunakan bahan bakar cangkang sebesar 20.5 % dan efisiensi PLTU 6 MW dari bahan bakar fibre 13 %. Oleh karena itu bahan bakar cangkang merupakan bahan bakar utama yang digunakan pada PLTU 6 MW

Preservation Island, Furneaux Group: Two hundred years of vegetation change

Preservation Island was the first area south of Sydney to experience the impact of European settlement. A recent survey of the vegetation resulted in the inventory of 140 plant species, 49 of these being introduced to the island. Ten vegetation types were mapped, some of these being disturbance disclimax communities. The island has a flora typical of many of the Furneaux Outer Islands. Since 1797, Allocasuarina verticillata, once the likely dominant tree on the island, has been depleted almost to extinction and grassland with a high proportion of exotic species has expanded to cover more than a third of the island. Exotic species propagules have been associated with human activity on the island but also with birds and by sea drift. The high levels of natural and human-related disturbance have encouraged establishment of introduced plants. Some obligate-seeding species on the island have been reduced to either precariously low numbers (Acacia ?genistifolia) or extinction (Callitris rhomboidea) by a high fire frequency. The biological productivity of the island was high at the time of initial human settlement because there was an extremely large muttonbird rookery, penguins, macropods and other animals. Scrub and low closed forest were more extensive. Most of the biological capital was exhausted within 30 or 40 years. The significance of the island in post-contact Australian history means that more historical remarks are recorded than would otherwise be expected for such an isolated place