Sunday 30 March 2014

Ronaldo - Greatest football player

Ronaldo Luís Nazário de Lima born 18 September 1976) commonly known as Ronaldo, is a retired Brazilian footballer. Popularly dubbed "the phenomenon", he is considered by experts and fans to be one of the greatest football players of all time..He is one of only three men to have won the FIFA World Player of the Year award three times or more, along with Zinedine Zidane andLionel Messi. He won his first Ballon d'Or in 1997 and won the award again in 2002.
Considered by many the most complete striker in the past thirty years, in 2007 he was named a member of the best starting eleven of all-time by France Football and was named to the FIFA 100, a list of the greatest footballers compiled by Pelé. In 2010, he was voted Goal.com's "Player of the Decade" in an online poll, gathering 43.63 percent of all votes and was also included as centre forward in the "Team of the Decade". In February 2010, Ronaldo announced that he would retire after the 2011 season, signing a two-year contract extension with Corinthians at the same time.
Ronaldo played for Brazil in 98 matches, scoring 62 goals, and is the second highest goalscorer for his national team. Aged 17, he was a part of the Brazilian squad that won the 1994 FIFA World Cup. At the 1998 World Cup he helped Brazil reach the final and won the Golden Ball for player of the tournament. He won a second World Cup in 2002 where he received the Golden Boot as top goalscorer. During the 2006 FIFA World Cup, Ronaldo became the highest goalscorer in World Cup history with his fifteenth goal, surpassing Gerd Müller's previous record of fourteen.
Having suffered a string of serious injuries throughout his career, Ronaldo retired on 14 February 2011, citing pain and hypothyroidism as the reasons for his premature retirement. In January 2013 he was named one of the six Ambassadors of the 2014 FIFA World Cup in Brazil, the others being Amarildo, Bebeto, Carlos Alberto Torres,Marta and Mario Zagallo

Saturday 29 March 2014

'Mending Wall'-poem-and summary--Robert Frost

                                           Robert Frost
The poet was born on 26th March, 1874 Frost’s parents were of Scottish and English descent and he lived in California and Sanfransisco during his early years. Frost's father was a teacher, and later he became the editor of the San Francisco Evening Bulletin .The poet lived in close association with rural life durin his early days and moved to the city later. So he frequently uses themes from rural life in New England in his poems. Most of his poems centre around complex, social and philosophical themes. He ranks one among the best American poets and was honoured for receiving four Pulitzer Prizes. His first poem, "My Butterfly: An Elegy" was published in the
November 8, 1894 edition of the New York Independent. He married Elinor Miriam White, and attended Harvard University for two years. Frost ‘s grandfather purchased a farm for the young couple in Derry, New Hampshire, and Frost worked on the farm for nine years and wrote many of the poems that later became famous. His attempts at farming were not successful and Frost returned to education as an English teacher at Pinkerton Academy from 1906 to 1911, then at the New Hampshire Normal School . In 1912, Frost sailed with his family to Great Britain, and his first book of poetry, A Boy's Will, was published the next year. In England he got the acquaintance of all the leading poets of the time. When the first world war began Frost returned to America in 1915 and resumed his vocation as a teacher and poet. He died a little more than two years later, in Boston, on January 29, 1963.
            
          Mending Wall"
Something there is that doesn't love a wall,
That sends the frozen-ground-swell under it,
And spills the upper boulders in the sun;
And makes gaps even two can pass abreast.
The work of hunters is another thing:
I have come after them and made repair
Where they have left not one stone on a stone,
But they would have the rabbit out of hiding,
To please the yelping dogs. The gaps I mean,
No one has seen them made or heard them made,
But at spring mending-time we find them there.
I let my neighbour know beyond the hill;
And on a day we meet to walk the line
And set the wall between us once again.
We keep the wall between us as we go.
To each the boulders that have fallen to each.
And some are loaves and some so nearly balls
We have to use a spell to make them balance:

"Stay where you are until our backs are turned!"
We wear our fingers rough with handling them.
Oh, just another kind of out-door game,
One on a side. It comes to little more:
There where it is we do not need the wall:
He is all pine and I am apple orchard.
My apple trees will never get across
And eat the cones under his pines, I tell him.
He only says, "Good fences make good neighbours."
Spring is the mischief in me, and I wonder
If I could put a notion in his head:
"Why do they make good neighbours? Isn't it
Where there are cows? But here there are no cows.
Before I built a wall I'd ask to know
What I was walling in or walling out,
And to whom I was like to give offence.
Something there is that doesn't love a wall,
That wants it down." I could say "Elves" to him,
But it's not elves exactly, and I'd rather
He said it for himself. I see him there
Bringing a stone grasped firmly by the top
In each hand, like an old-stone savage armed.
He moves in darkness as it seems to me,
Not of woods only and the shade of trees.
He will not go behind his father's saying,
And he likes having thought of it so well
He says again, "Good fences make good neighbors."
                     Poem Summary
In “The Mending Wall” Robert Frost makes use of the image of a wall to drive home the lesson that people unnecessarily create boundaries around themselves. The wall separating the farm of two neighbors is introduced as a primary symbol in the poem. Frost begins the poem by stating that there is something in nature that does not like wall. So it swells the ground beneath and manages to disintegrate the wall to such an extent that even two men can pass abreast through the opening. The poet is sure that the destruction of walls is not the work of rabbit hunters. The force that destroys the wall is unnameable. There is a mystery about who or what doesn't like a wall. No one has seen the holes being made but at springtime there are big holes in the wall.The narrator and his neighbour meet on a specified date and rebuild the wall. Rebuilding the wall is a laborious task. The stones are uneven in size and shape and they have to balance them delicately.They are tired by the time the wall is rebuilt.The speaker reinforces the idea that these breaks created by nature are more mysterious than those made by the hunters. This action cannot be observed, though the effects are consistent year after year. The speaker (poet) does not like a wall. He keeps rebuilding it only to please his neighbor. Very humorously Frost says:

“He is all pine and I am apple orchard.
My apple trees will never get across
And eat the cones under his pines, I tell him.”

Both of them have different crops in their orchard. The pine cones will not walk up and eat the apples or vice versa. Yet his neighbour insists on building walls saying that good fences make good neighbours. The separation between them is also emphasized in the fact that they walk on opposite sides of the wall and as they are each responsible for replacing the stones that have fallen on each one’s side. While they are performing this act together, they do not actually assist each other.

Frost’s tone becomes playful in the lines, when he says that farmers often use fences to keep their livestock separated. Such a fence is unnecessary because they have only pine and apple trees, not cows or cattle. Again, the speaker considers trying to provoke his neighbor with practical objections, but he never makes this statement out loud.

In the concluding sections, Frost becomes philosophical and speculates abstractly. He wants to know what they are “walling in” and “walling out.” The double function of a wall is addressed, for not only are outsiders prevented from entry, but insiders are trapped inside. The speaker considers the possibility that walls “give offence” as he himself seems to be slightly offended, but he never reaches a conclusion about what it is within himself that is either walled in or walled out. Nor does he say that he himself doesn't love a wall, only that “something” doesn't  He muses that “Elves” might have destroyed their wall. In the speaker’s eyes the neighbor resembles a savage, an old storage man armed with a stone. He implies that the neighbor is also using the stones as weapons; he is “armed.” In a sense, then, the fence becomes a weapon, even if its purpose is primarily defense. The speaker then moves from thoughts of the Stone Age to thoughts of the Dark Ages, where darkness functions as a symbol for a lack of insight that is understood as progress. His darkness is more than physical darkness provided by the shade. There is also emotional darkness in his refusal to leave the wall unmended. Frost concludes saying that his neighbor will not change his ideas, nor will he give up the practices set forth by his father. Like a savage the man keeps repeating “Good fences make good neighbors”.

Friday 28 March 2014

Satellite television

Satellite television is television programming delivered by the means of communications satellite and received by an outdoor antenna, usually a parabolic reflector generally referred to as a satellite dish, and as far as household usage is concerned, a satellite receiver either in the form of an external set-top box or a satellite tuner module built into a television set. Satellite television tuners are also available as a card or a USB peripheral to be attached to a personal computer. In many areas of the world satellite television provides a wide range of channels and services, often to areas that are not serviced by terrestrial or cable providers.
Direct-broadcast satellite television comes to the general public in two distinct flavors – analog and digital. This necessitates either having an analog satellite receiver or a digital satellite receiver. Analog satellite television is being replaced by digital satellite television and the latter is becoming available in a better quality known as high-definition television.
Satellites used for television signals are generally in either naturally highly elliptical (with inclination of +/-63.4 degrees and orbital period of about twelve hours, also known as Molniya orbit) or geostationary orbit 37,000 km (23,000 mi) above the earth's equator.
Satellite television, like other communications relayed by satellite, starts with a transmitting antenna located at an up link facility. Up link satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter. The increased diameter results in more accurate aiming and increased signal strength at the satellite. The uplink dish is pointed toward a specific satellite and the up linked signals are transmitted within a specific frequency range, so as to be received by one of the transponders tuned to that frequency range aboard that satellite. The transponder 'retransmits' the signals back to Earth but at a different frequency band (a process known as translation, used to avoid interference with the uplink signal), typically in the C-band (4–8 GHz) or Ku-band (12–18 GHz) or both. The leg of the signal path from the satellite to the receiving Earth station is called the downlink.
A typical satellite has up to 32 transponders for Ku-band and up to 24 for a C-band only satellite, or more for hybrid satellites. Typical transponders each have a bandwidth between 27 and 50 MHz. Each geostationary C-band satellite needs to be spaced 2° from the next satellite to avoid interference; for Ku. the spacing can be 1°. This means that there is an upper limit of 360/2 = 180 geostationary C-band satellites and 360/1 = 360 geostationary Ku-band satellites. C-band transmission is susceptible to terrestrial interference while Ku-band transmission is affected by rain (as water is an excellent absorbed of microwaves at this particular frequency). The latter is even more adversely affected by ice crystals in thunder clouds.
On occasion, sun outage will occur when the sun lines up directly behind the geostationary satellite the reception antenna is pointing to. This will happen twice a year at around midday for a two-week period in the spring and in the fall, and affects both the C-band and the Ku-band. The line-up swamps out all reception for a few minutes due to the sun emitting microwaves on the same frequencies used by the satellite's transponders.
The down linked satellite signal, quite weak after traveling the great distance (see inverse-square law), can be collected by using a parabolic receiving dish, which reflects the weak signal to the dish's focal point. Mounted on brackets at the dish's focal point is a device called a feed horn. This feed horn is essentially the flared front-end of a section of wave guide that gathers the signals at or near the focal point and 'conducts' them to a probe or pickup connected to a low-noise block down converter or LNB. The LNB amplifies the relatively weak signals, filters the block of frequencies in which the satellite television signals are transmitted, and converts the block of frequencies to a lower frequency range in the L-band range. The evolution of LNBs was one of necessity and invention.
The original C-Band satellite television systems used a Low Noise Amplifier connected to the feed horn at the focal point of the dish. The amplified signal was then fed via very expensive and sometimes 50 ohm impedance gas filled hardline coaxial cable to an indoor receiver or, in other designs, fed to a down converter (a mixer and a voltage tuned oscillator with some filter circuitry) for down conversion to an intermediate frequency. The channel selection was controlled, typically by a voltage tuned oscillator with the tuning voltage being fed via a separate cable to the headend. But this design evolved.
Designs for microstrip based converters for Amateur Radio frequencies were adapted for the 4 GHz C-Band. Central to these designs was concept of block downconversion of a range of frequencies to a lower, and technologically more easily handled block of frequencies (intermediate frequency).
The advantages of using an LNB are that cheaper cable could be used to connect the indoor receiver with the satellite television dish and LNB, and that the technology for handling the signal at L-Band and UHF was far cheaper than that for handling the signal at C-Band frequencies. The shift to cheaper technology from the 50 Ohm impedance cable and N-Connectors of the early C-Band systems to the cheaper 75 Ohm technology and F-Connectors allowed the early satellite television receivers to use, what were in reality, modified UHFtelevision tuners which selected the satellite television channel for down conversion to another lower intermediate frequency centered on 70 MHz where it was demodulated. This shift allowed the satellite television DTH industry to change from being a largely hobbyist one where receivers were built in low numbers and complete systems were expensive (costing thousands of dollars) to a far more commercial one of mass production.
Direct broadcast satellite dishes are fitted with an LNBF, which integrates the feed horn with the LNB.
In the United States, service providers use the intermediate frequency ranges of 950-2150 MHz to carry the signal to the receiver. This allows for transmission of UHF band signals along the same span of coaxial wire at the same time. In some applications (DirecTV AU9-S and AT-9), ranges the lower B-Band and upper 2250-3000 MHz, are used. Newer LNBFs in use by DirecTV referred to as SWM (Single Wire Multiswitch), See also Single Cable Distribution, use a less limited frequency range of 2-2150 MHz.
The satellite receiver or set-top box demodulates and converts the signals to the desired form (outputs for television, audio, data, etc.). Sometimes, the receiver includes the capability to unscramble or decrypt the received signal; the receiver is then called an integrated receiver/decoder or IRD. The cable connecting the receiver to the LNBF or LNB should be of the low loss type RG-6, quad shield RG-6 or RG-11, etc. RG-59 is not recommended for this application as it is not technically designed to carry frequencies above 950 MHz, but will work in many circumstances, depending on the quality of the coaxial wire.
A practical problem relating to satellite home reception is that basically an LNB can only handle a single receiver. This is due to the fact that the LNB is mapping two different circular polarizations – right hand and left hand – and in the case of the K-band two different reception bands – lower and upper – to one and the same frequency band on the cable. Depending on which frequency a transponder is transmitting at and on what polarization it is using, the satellite receiver has to switch the LNB into one of four different modes in order to receive a specific desired program on a specific transponder. This is handled by the receiver using the DiSEqC protocol to control the LNB mode. If several satellite receivers are to be attached to a single dish a so-called multiswitch will have to be used in conjunction with a special type of LNB. There are also LNBs available with a multiswitch already integrated. This problem becomes more complicated when several receivers are to use several dishes (or several LNBs mounted in a single dish) pointing to different satellites.
A common solution for consumers wanting to access multiple satellites is to deploy a single dish with a single LNB and to rotate the dish using an electric motor. The axis of rotation has to be set up in the north-south direction and, depending on the geographical location of the dish, have a specific vertical tilt. Set up properly the motorized dish when turned will sweep across all possible positions for satellites lined up along the geostationary orbit directly above the equator. The disk will then be capable of receiving any geostationary satellite that is visible at the specific location, i.e. that is above the horizon. The DiSEqC protocol has been extended to encompass commands for steering dish rotors.

Tuesday 25 March 2014

La Luna-

La Luna es el único satélite natural de la Tierra y la luna quinto más grande del Sistema Solar. Es el satélite natural más grande de un planeta en el Sistema Solar en relación al tamaño de su primario,  que tiene el 27% del diámetro y de 60 % de la densidad de la Tierra , dando lugar a 1/81 ( 1.23 %) de su masa. Entre los satélites con densidades conocidas, la Luna es el segundo más densa , después de Io, un satélite de Júpiter .
La Luna está en rotación síncrona con la tierra, mostrando siempre la misma cara con su cara cerca de marcado por Maria volcánica oscura que llenan entre las montañas corticales antiguas brillantes y los cráteres prominentes del impacto . Es el objeto más luminoso en el cielo después del sol. Aunque parece un blanco muy brillante , su superficie es en realidad oscura , con una reflectancia sólo ligeramente mayor que la de asfalto desgastado . Su prominencia en el cielo y su ciclo regular de fases , desde épocas antiguas , hecho la luna una influencia cultural importante en lengua, calendarios , arte y mitología. Influencia gravitacional de la luna produce las mareas del océano y el alargamiento minucioso del día. Distancia orbital actual de la Luna es de unos treinta veces el diámetro de la Tierra , haciendo que tenga un tamaño aparente en el cielo casi la misma que la del sol. Esto permite que la Luna cubra el Sun casi exacto en eclipse total de sol . Esta coincidencia de tamaño visual aparente es una coincidencia. Distancia lineal de la Luna de la Tierra está aumentando a un ritmo de 3.82 ± 0.07 cm por año , pero esta tasa no es constante. 
La Luna se cree que se formó hace cerca de 4,5 millones de años, no mucho después de la Tierra. Aunque ha habido varias hipótesis de su origen en el pasado, la actual explicación más aceptada es que la Luna se formó de los escombros que queda después de un impacto gigante entre la Tierra y un cuerpo del tamaño de Marte .
La Luna es el único cuerpo celeste que no sea la Tierra en la que los seres humanos han establecido actualmente pie. Programa Luna de la Unión Soviética fue el primero en llegar a la Luna con la nave espacial no tripulada en 1959 , el programa Apolo de la NASA de los Estados Unidos alcanzó las únicas misiones tripuladas a la fecha, comenzando con la primera tripulada misión en órbita lunar por el Apolo 8 en 1968 , y seis tripulada aterrizajes lunares entre 1969 y 1972 , con la primera siendo Apolo  . Estas misiones regresaron más de 380 kg de rocas lunares , que se han utilizado para desarrollar una comprensión geológica de origen de la Luna , la formación de su estructura interna, y su historia posterior .
Después de la misión Apollo 17 en 1972 , la Luna ha sido visitado por la nave espacial no tripulada . De éstas , las misiones orbitales han dominado : Desde 2004 , Japón , China, India, Estados Unidos, y la Agencia Espacial Europea han enviado orbitadores lunares cada uno , que han contribuido a confirmar el descubrimiento de hielo de agua lunar en cráteres permanentemente sombreados en los polos y limita en el regolito lunar. La era post- Apolo también ha visto dos misiones rover : la final de la misión Lunokhod Soviética en 1973 , y continua misión Chang'e 3 de China, que desplegó su rover Yutu el 14 de diciembre de 2013.
Las futuras misiones tripuladas a la Luna han sido planeadas , incluyendo el gobierno , así como los esfuerzos de financiación privada . La Luna sigue siendo , en el marco del Tratado sobre el Espacio Ultraterrestre , la libertad de todas las naciones para explorar para fines pacíficos .

Adolescence

Adolescence (from Latin adolescence, meaning "to grow up") is a transitional stage of physical and psychological human development that generally occurs during the period from puberty to legal adulthood (age of majority). The period of adolescence is most closely associated with the teenage years, though its physical, psychological and cultural expressions may begin earlier and end later. For example, although puberty has been historically associated with the onset of adolescent development, it now typically begins prior to the teenage years and there has been a normative shift of it occurring in preadolescence, particularly in females (see early and precocious puberty). Physical growth, as distinct from puberty (particularly in males), and cognitive development generally seen in adolescence, can also extend into the early twenties. Thus chronological age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence.
A thorough understanding of adolescence in society depends on information from various perspectives, including psychology, biology, history, sociology, education, and anthropology. Within all of these perspectives, adolescence is viewed as a transitional period between childhood and adulthood, whose cultural purpose is the preparation of children for adult roles. It is a period of multiple transitions involving education, training, employment and unemployment, as well as transitions from one living circumstance to another.
The end of adolescence and the beginning of adulthood varies by country and by function, and furthermore even within a single nation state or culture there can be different ages at which an individual is considered (chronologically and legally) mature enough for society to entrust them with certain privileges and responsibilities. Such milestones include driving a vehicle, having legal sexual relations, serving in the armed forces or on a jury, purchasing and drinking alcohol, voting, entering into contracts, finishing certain levels of education, and marriage. Adolescence is usually accompanied by an increased independence allowed by the parents or legal guardians and less supervision as compared to preadolescence.
In popular culture, adolescent characteristics are attributed to physical changes and what is called raging hormones.There is little evidence that this is the case, however. In studying adolescent development, adolescence can be defined biologically, as the physical transition marked by the onset of puberty and the termination of physical growth; cognitively, as changes in the ability to think abstractly and multi-dimension ally; or socially, as a period of preparation for adult roles. Major pubertal and biological changes include changes to the sex organs, height, weight, and muscle mass, as well as major changes in brain structure and organization. Cognitive advances encompass both increases in knowledge and in the ability to think abstractly and to reason more effectively. The study of adolescent development often involves interdisciplinary collaborations. For example, researchers in neuroscience or bio-behavioral health might focus on pubertal changes in brain structure and its effects on cognition or social relations. Sociologists interested in adolescence might focus on the acquisition of social roles (e.g., worker or romantic partner) and how this varies across cultures or social conditions.Developmental psychologists might focus on changes in relations with parents and peers as a function of school structure and pubertal status.