Tuesday, May 27, 2008

Carbon-Dioxide Frost Settling from Seasonal Outbursts on Mars (Movie)

video

This movie, constructed by overlaying a time series of images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), shows seasonal changes and unearthly processes that occur in Mars' south polar seasonal frost cap. Mars' seasonal caps consist of frozen carbon dioxide mixed with smaller amounts of water ice frost and dust. The different composition of Mars' seasonal caps than Earth's seasonal caps (water-ice snow), plus the lower pressure of the Martian atmosphere, inevitably make springtime recession of the seasonal cap different than the snowmelt that characterizes retreat of Earth's seasonal cap. To monitor Mars' seasonal changes, CRISM repeatedly targets specific regions as Mars' seasons change. Results shown here are evidence that as warming carbon-dioxide ice vaporizes, some is trapped under the ice slab from which pressurized outbursts occur.
The released gas expands, cools, and some of it refreezes and falls back to the surface as bright fans. The region shown in this movie, known informally as Manhattan, is located at 86.3 degrees south latitude, 99 degrees east longitude. To represent the content of the spectral images, two versions of the data are shown side-by-side. The left image was constructed from extended visible wavelengths, to look similar to color images from the High Resolution Imaging Science Experiment (HiRISE) camera. The right image is infrared false-color, with red being the reflectance at 1.30 micrometers, green being depth of the water ice absorption centered at 1.5 micrometers, and blue being depth of the carbon dioxide ice absorption centered at 1.435 micrometers. In this color scheme, surfaces with higher water ice content will appear greenish, while bright carbon dioxide ice will appear magenta. Areas covered by dust will appear dark. In both images, north is to the right. The four time steps in the movie were taken at solar longitudes (Ls) ranging from 195 through 226. (Solar longitude is a measure of seasons, where 180 is southern spring equinox and 270 is southern summer solstice.)
The first frame shows a number of spots and dark fan-shaped features, with a higher concentration of spots on a slope in the middle of the scene. The dark fans show multiple directions, generally indicating wind coming out of the east.
The second frame was taken just a few days after the prior one and starts to show color variations in the fans.
The third frame records appearance of bright (bluish) fans in addition to the dark fans. The bright fans are slightly more bluish in the false-color image at right, indicating enrichment in carbon dioxide ice. The tails of the dark fans are more greenish, indicated a slight enhancement of water ice.
The fourth and final frame shows distinct bright fans that appear magenta in the false-color image, indicating carbon dioxide ice with little evidence of water ice. However the surrounding surface is greenish, suggesting small amounts of water ice contamination. The tails of the dark fans appear to be more greenish in the infrared than the surrounding ice, suggesting a slight enhancement of the water ice contamination. The difference between the directions of dark and bright fans suggests changes in the wind direction, perhaps as part of a diurnal cycle or pattern. CRISM science team members working with these data believe that they are seeing evidence for a process first proposed based on data from the Thermal Imaging System (THEMIS) instrument on Mars Odyssey.
In this hypothesis, sunlight penetrating the ice warms the underling soil and causes carbon dioxide frost to vaporize at its base. At first the gas is trapped under the frost; when it is released, the expanding gas cools and part of it refreezes to form carbon dioxide frost in the magenta-colored fans. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.
CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials — leading to new understanding of the climate.

Wednesday, May 07, 2008

Firewall

The Firewalls FAQ (http://www.faqs.org/faqs/firewalls-faq/) defines a firewall as "a system or group of systems that enforces an access control policy between two networks." In the context of home networks, a firewall typically takes one of two forms:

* Software firewall - specialized software running on an individual computer, or
* Network firewall - a dedicated device designed to protect one or more computers.

Both types of firewall allow the user to define access policies for inbound connections to the computers they are protecting. Many also provide the ability to control what services (ports) the protected computers are able to access on the Internet (outbound access). Most firewalls intended for home use come with pre-configured security policies from which the user chooses, and some allow the user to customize these policies for their specific needs.

Tuesday, May 06, 2008

Videophone

The widest use of video telephony occurs in mobile phones, as nearly all mobile phones supporting UMTS networks work as videophones using an internal camera, and are able to make video calls wirelessly to other UMTS users in the same country or internationally. As of Q2 2007, there are more than 131 million UMTS users on 134 networks in 59 countries
Videophones can also be used by the deaf to communicate with sign language over a distance. In US the FCC pays companies for providing Video Relay Service to deaf and hard-of-hearing individuals, where they use a videophone to talk through a sign-language translator to people using audio phones. Videophones are used to do on-site sign-language translation. The relatively low cost and widespread availability of mobile phones with video calling capabilities have given the deaf people new possibilities to communicate with the same ease as others, with some wireless operators even starting up free sign language gateways.
Videotelephony is also used in large corporate conferencing setups, and is supported by systems such as Cisco Unified Communications Manager, and similar systems from companies such as Tandberg, Radvision, and Polycom.

Latest Version Of Mobile

Mobile phones plays a major role in our daily modern life..Because they are the better,
cheaper and easier ways to communicate.
Technology and fashion have given a number of latest and advanced handsets to suit the needs of every segment of mobile users. Orange mobile phones rock the world of mobile phone with their stunning looks and advanced features and also with the quality.
Every manufacturer trying the best to insert advanced technology in the mobile phones for the sake of users. Orange mobile phones really have done miracle in the market with their stunning features, as well as functions. Orange mobile phones come with 3G technology, which offers wireless voice telephony with broadband wireless data, in addition with, video calling capabilities.
SPV M 5000 is also another latest endeavour from Orange, it possesses the Microsoft windows, which enables you to work with word, excel and power point on your mobile phone.This is one of the advance version.. It also has a large memory and the latest Active Sync 4.0 weighing 285g.. Orange Mobile Phones provide better communication services ,Rather than any other ordinary handset. They also have made communication impulsive and easily available part of day to day life.