Influence of Current Pulse Shape on Directly Modulated Systems Performance in Metro Area Optical Networks

Due to the fact that a metro network market is very cost sensitive, direct modulated schemes appear attractive. In this paper a CWDM (Coarse Wavelength Division Multiplexing) system is studied in detail by means of an Optical Communication System Design Software; a detailed study of the modulated current shape (exponential, sine and gaussian) for 2.5 Gb/s CWDM Metropolitan Area Networks is performed to evaluate its tolerance to linear impairments such as signal-to-noise-ratio degradation and dispersion. Point-to-point links are investigated and optimum design parameters are obtained. Through extensive sets of simulation results, it is shown that some of these shape pulses are more tolerant to dispersion when compared with conventional gaussian shape pulses. In order to achieve a low Bit Error Rate (BER), different types of optical transmitters are considered including strongly adiabatic and transient chirp dominated Directly Modulated Lasers (DMLs). We have used fibers with different dispersion characteristics, showing that the system performance depends, strongly, on the chosen DML?fiber couple.

Cloning of thermostable DNA polymerases from hyperthermophilic marine Archaea with emphasis on Thermococcus sp. 9 degrees N-7 and mutations affecting 3'-5' exonuclease activity.

Five extremely thermophilic Archaea from hydrothermal vents were isolated, and their DNA polymerases were cloned and expressed in Escherichia coli. Protein splicing elements (inteins) are present in many archaeal DNA polymerases, but only the DNA polymerase from strain GB-C contained an intein. Of the five cloned DNA polymerases, the Thermococcus sp. 9 degrees N-7 DNA polymerase was chosen for biochemical characterization. Thermococcus sp. 9 degrees N-7 DNA polymerase exhibited temperature-sensitive strand displacement activity and apparent Km values for DNA and dNTP similar to those of Thermococcus litoralis DNA polymerase. Six substitutions in the 3'-5' exonuclease motif I were constructed in an attempt to reduce the 3'-5' exonuclease activity of Thermococcus sp. 9 degrees N-7 DNA polymerase. Five mutants resulted in no detectable 3'-5' exonuclease activity, while one mutant (Glul43Asp) had <1% of wild-type activity.

Thames Tunnel, London, England, 1827 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan of the roads and main objects on the eastern part of London : as connected with the tunnel excavating under the Thames from Rotherhithe to Wapping, projected by M.I. Brunel, C.E. F.R.S., 1827. It was published by H. Teape & Son in 1827. Scale [ca. 1:48,000]. The image inside the map neatline is georeferenced to the surface of the earth and fit to the British National Grid coordinate system (British National Grid, Airy Spheroid OSGB (1936) Datum). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, docks, drainage, canals, selected buildings, and more. Includes text, advertisement, and engravings: View of the Thames River -- View of the Interior of the Thames Tunnel -- View of the iron shield compartments for workers. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

Traffic capacity through work zones on urban freeways. Interim report.

Texas State Department of Highways and Public Transportation, Transportation Planning Division, Austin

The model T Ford car, its construction, operation and repair; a complete practical treatise explaining the operating principles of all parts of the Ford automobile, with complete instructions for driving and maintenance; includes the most thorough and easily understood illustrated instructions on Ford repairing ever published; based on five years' experience of a Ford operator--invaluable to all Ford owners, dealers, salesmen, drivers and repair men--every phase of the subject treated in a non-technical yet comprehensive manner,

Mode of access: Internet.

Hadleigh Castle, The Mouth of the Thames--Morning after a Stormy Night

John Constable; 3 ft. 11 63/64 in.x 5 ft. 4 49/64 in.; oil on canvas

The Thames and its tributaries; or, Rambles among the rivers.

Added t.-p. illustrated in each volume.

The complete works of Henry Fielding, esq., with an essay on the life, genius and achievement of the author /

This ed. ... is limited to 375 numbered copies for Great Britain ... This is copy no. 272.

Standard practical plumbing; an exhaustive treatise on all branches of plumbing construction, including drainage and venting, ventilation, hot and cold water supply and circulation; showing the latest and best plumbing practice, special attention being given to the skilled work of the plumber, and to the theory underlying plumbing devices and operations,

Mode of access: Internet.

The complete works of Henry Fielding : with an essay on the life, genius and achievement of the author /

"This edition ... is limited to 375 numbered copies for Great Britain."

Concrete on the farm and in the shop; a complete practical treatise on the commonest every-day uses of concrete,

Mode of access: Internet.

The life of Major-General William Henry Harrison: comprising a brief account of his important civil and military services, and an accurate description of the council at Vincennes with Tecumseh, as well as the victories of Tippecanoe, Fort Meigs and the Thames.

Another issue appeared in the same year having different frontispiece, 4 plates, different spacing of the lines of text.

Horseless vehicles, automobiles, motor cycles operated by steam, hydro-carbon, electric and pneumatic motors; a practical treatise for ... everyone interested in the development, use and care of the automobile, including a special chapter on how to build an electric cab, with detail drawings.

Mode of access: Internet.

Modern American lathe practice; a new complete and practical work on the "king of machine shop tools," the American lathe. Giving its origin and development. Its design. Its various types as manufactured by different builders ... etc.

Mode of access: Internet.

Saw filing and management of saws; a practical treatise on filing, gumming, swaging, hammering, and brazing band saws, etc.

Includes index.