Thursday, September 29, 2011

OPERATING SYSTEMS


Figure 4.12 (adapted from Madnick and Donovan, 1974) is a simplified process model of you, in which there are only two states: sleeping and waking. You make the transistion from waking to sleeping when you are tired, and from sleeping to waking when alarm clock goes off.


 


Alarm clock rings
 
Sleeping
 
Waking
 
                                                                       


a.       Add three more states to the diagram (for example, one might be eating).
Answer:

b.      State all of the possible transitions among the five states.
Answer:
-          SUSPEND BLOCKED then BLOCKED → If a process in the RUNNING state requires more memory, then at least one BLOCKED process can be swapped out of memory onto disk. The transition can also be made for the BLOCKED process if there are READY processes available, and the OS determines that the READY process that it would like to dispatch requires more main memory to maintain adequate performance.
-          SUSPEND BLOCKED then SUSPEND READY A process in the SUSPEND BLOCKED state is moved to the SUSPEND READY state when the event for which it has been waiting occurs. Note that this requires that the state information concerning suspended processes be accessible to the OS.
-          SUSPEND READY then READY  When there are no READY processes in main hbbbbbmemory, the OS will need to bring one in to continue execution. In addition, it might be the case that a process in the READY SUSPEND state has higher priority than any of the processes in the READY state. In that case, the OS designer may dictate that it is more important to get at the higher priority process than to minimise swapping.
-          SUSPENDED but READY  Normally, the OS would be designed so that the preference would be to suspend a BLOCKED process rather than a READY one.

Sunday, April 10, 2011

Digital Signals and Systems




Problems

1. Define the term "sample" as it applies to digital systems.
-A sample is a "snap-shot" in time of an analog signal. It has a finite resolution or   accuracy  an represents the value of the analog signal at only one instant in time. 


2. Define the term "sampling rate" as it applies to digital system
A sampling rate is the rate (usually in samples per second) at which the digital system  takes its samples or "snap-shots". If a sampling rate is 10 samples/second, then the digital system measures the analog value ten times every second. 



3. What are the two primary problems that sampling could cause?


Firstly, if the Sampling too slowly may cause the digital system to miss "faster" details of an analog signal.

Secondly, if the resolution or accuracy of the digital system that is measuring the analog signal is too low, the system may not be able to discern the difference between two samples.



4. Name the three parts of the system used to input an analog signal
into a digital system and describe their purpose.

There is System that is used to get/catch/sense analog signal in desired environment in our device/s like PC/phone via Conversion System of analog to digital signal that use a SENSOR to catch analog signal and it is amplified and refined before it goes to ADC or analog-to-digital converter.

Initially the captured analog signal is first weak and noisy before it will be conditioned to be passed on (ADC) for analog to digital converter.

Secondly, the captured analog signal will be conditioned for amplifying or refining analog signal (weak and noisy analog signal), the analog signal must be amplified in order to reach its destination and after it is amplified the weak and noisy analog signal will be strong and clean analog signal, enough to be converted to digital signal.

Lastly, the strong and clean analog signal will be converted to analog to digital signal. The results of this system are viewed like the table of numbers and 0’s and 1’s that is in computer readable form.
                                    


5. Name four benefits of a digital system over an analog system.

There are benefits to using data in a digital format rather than analog.

First, if an analog signal is transmitted over long distances. The noise that is attached to the signal will get amplified and converted to digital signal.

Secondly, noise cannot attach itself to a digital signal. Once an analog signal has been converted to a sequence of numbers, the signal's characteristics remain the same as long as the numbers don't change.

Thirdly, the benefit  that once a signal is turned into a sequence of
numbers, mathematical algorithms can be used to operate on the data.
Disciplines such as Digital Signal Processing (DSP) and the study of
wavelets allow for much more accurate processing of signals than
analog systems were ever able to achieve.

Lastly, a sequence of digital numbers can also be stored more compactly
than an analog signal, e.i. MP3 devices in addition, supplementary data can be stored along with the samples for information such as digital watermarking for security or codes for error
checking or error correction.

6. Name three drawbacks of a digital system over an analog system.

Firstly, if the samples are taken too slowly, details of the analog input are missed.

Secondly, if the accuracy of the samples is not fine enough, the signal may not be precisely represented with the digital values.

Lastly, additional hardware is required to convert the signal from analog to digital.



7. True or False: Since non-periodic pulse trains do not have a
predictable format, there are no defining measurements of the
signal.

True, because it has no predictable format because, do not have a
characteristic pattern in their changes between logic 1 and logic 0.



8. If a computer runs at 12.8 GHz, what is the period of its clock
signal?



9. If the period of a periodic pulse train is 125 nanoseconds, what is
the signal's frequency?

10. If the period of a periodic pulse train is 50 microseconds, what
should the pulse width, tw, be to achieve a duty cycle of 15%?
-25%

11. True or False: A signal’s frequency can be calculated from its duty

cycle alone. 
- True




Monday, February 14, 2011

Theories of Socialization and Personality

THEORIES OF SOCIALIZATION AND PERSONALITY
(SOCIOLOGICAL PERSPECTIVE)

PROPONENT

THEORY

SIGMUND FREUD

PSYCHOANALYSIS/PSYCHODYNAMICS

JEAN PIAGET

COGNITIVE DEVELOPMENT

LAWRENCE KOHLBERG

MORAL REASONING

CAROL GILLIGAN

BRINGING IN GENDER

CHARLES HORTON COOLEY

THE LOOKING GLASS SELF

GEORGE HERBERT MEAD

THE SOCIAL SELF

ERIK ERIKSON

PSYCHOSOCIAL DEVELOPMENT

ALFRED ADLER

INDIVIDUAL PSYCHOLOGY

CARL JUNG

ANALYTICAL PSYCHOLOGY

KAREN HORNEY

PSYCHOANALYTIC SOCIAL THEORY

ERIC FROMM

HUMANISTIC PSYCHOANALYSIS

HARRY STACK SULLIVAN

INTERPERSONAL THEORY

MELANIE KLEIN

OBJECT RELATIONS THEORY

ABRAHAM MASLOW

MOTIVATION AND PERSONALITY

CARL ROGERS

REAL SELF VS. IDEAL SELF

GEORGE KELLY



----------------------------------------------------------------------------------------------------------------------------------------------------


Psychoanalysis/psychodynamics


PERSONAL CONTRUCT THEORY




Monday, August 23, 2010

8 Things You Didn't Know About Toothpaste

8 Things You Didn't Know About Toothpaste

Faced with dozens of different products promising to make your teeth fresher, whiter and cavity-free, it’s no wonder you wander aimlessly down the toothpaste aisle. To help you pick wisely, we turned to the pros for the scoop on what ingredients to look for, whether gel or paste formulas are right for you and just how much you need to squeeze onto your brush. It’s never too late to get your pearly whites in tip-top shape, so read on to find out how!

1. It’s all about the fluoride.
With a host of ingredients in toothpaste, it’s easy to lose sight of what’s essential. But no matter what your individual needs are (i.e., tartar control, whitening, breath-freshening and so on), dental hygienists agree that fluoride is a must. According to the Academy of GeneralDentistry, brushing with fluoride toothpaste twice daily can reduce tooth decayby as much as 40 percent. “Even in areas where there is water fluoridation, the added fluoride in toothpaste has been shown to be very beneficial,” says Caryn Loftis-Solie, RDH, president of the American Dental Hygiene Association (ADHA).

2. Look for the seal of approval.
While it’s tempting to save some cash with a generic brand of toothpaste, you may actually be getting an ineffective—and potentially harmful—product. “You should always look for the ADA Seal when choosing a toothpaste,” says Clifford Whall, PhD, director of the American Dental Association (ADA) Seal of Acceptance Program. “Only those products have the scientific data to back up their claims and have been proven to meet our criteria for safety and effectiveness.” With 50-plus approved toothpastes on shelves, it’s easy to find a tube that’s right for you and your budget.

3. Whitening toothpastes work—at least to a certain degree.
Countless products promise a whiter smile, but do they really deliver? “Whitening toothpastes—like all toothpastes—contain mild abrasives to help remove surface stains on your teeth,” says Dr. Whall. “The shape of the particles used in whitening products, though, is modified to clean those stains away better, so you’ll see a noticeable difference in how your teeth look.” However, according to Dr. Whall, these products don’t contain bleach, making it impossible for them to brighten your smile as dramatically as professional whitening treatments.

4. Less is more.
Despite what you see on commercials, a brush full of toothpaste won’t clean your pearly whites any better than half that amount, according to E. Jane Crocker, RHD, president of the Massachusetts Dental Hygienists’ Association. “All you need is a pea-size amount of toothpaste—yes, I mean the little green vegetable!” Not only will that get the job done effectively (by cleaning and removing plaque, stains and food debris), you’ll also extend the life of your tube.

5. How you brush is more important than what you brush with.
You can buy the best toothpaste and toothbrush on the market, but if you aren’t brushing correctly you won’t see results. “To do it properly, you need to position the brush at a 45 degree angle so that you get some of the bristles in between the tooth and the gums,” says Dr. Whall. “Move the brush in small circles in those areas, and then continue on to the rest of the teeth. This process should take about one to two minutes to complete.” View the ADA’s step-by-step guide to brushing and flossing here.

6. Organic toothpastes can be just as effective as regular.
If you’re willing to spend a little more to go green, natural and organic toothpastes can be a good eco-friendly alternative to commercial brands—provided they contain fluoride. “Natural and organic toothpastes that include fluoride in their ingredients are as effective as regular toothpastes with fluoride,” says Crocker. You’ll also be avoiding artificial preservatives, sweeteners and dyes.

7. What’s inside your toothpaste might surprise you.
You may not recognize the names listed on the side of the tube, but ingredients like seaweed and detergent can be found in many fluoride toothpastes. According to the ADA, common thickening agents include seaweed colloids, mineral colloids and natural gums. And for that quintessential foaming action, most products rely on detergents such as sodium lauryl sulfate—also found in many shampoos and body washes—that are deemed 100 percent safe and effective by the ADA.

8. Pastes or gels—they all do the trick.
You may have heard that one works better than the other but, according to the experts, they all clean teeth equally well. “Other than flavor, texture and how it makes a person feel, there aren’t any major differences among the various forms,” says Crocker. “I think it comes down to personal preference, which might come through trial and error. I encourage my patients to use whichever product encourages them to brush.”

Monday, June 14, 2010

kl.edgar

A poem from his heart and I shared by.....

From Edgar Allan Poe


Once upon a midnight dreary, while I pondered weak and weary,

Over many a quaint and curious volume of forgotten lore,
While I nodded, nearly napping, suddenly there came a tapping,
As of some one gently rapping, rapping at my chamber door.
`'Tis some visitor,' I muttered, `tapping at my chamber door -
Only this, and nothing more.'

Ah, distinctly I remember it was in the bleak December,
And each separate dying ember wrought its ghost upon the floor.
Eagerly I wished the morrow; - vainly I had sought to borrow
From my books surcease of sorrow - sorrow for the lost Lenore -
For the rare and radiant maiden whom the angels named Lenore -
Nameless here for evermore.

And the silken sad uncertain rustling of each purple curtain
Thrilled me - filled me with fantastic terrors never felt before;
So that now, to still the beating of my heart, I stood repeating
`'Tis some visitor entreating entrance at my chamber door -
Some late visitor entreating entrance at my chamber door; -
This it is, and nothing more,'

Presently my soul grew stronger; hesitating then no longer,
`Sir,' said I, `or Madam, truly your forgiveness I implore;
But the fact is I was napping, and so gently you came rapping,
And so faintly you came tapping, tapping at my chamber door,
That I scarce was sure I heard you' - here I opened wide the door; -
Darkness there, and nothing more.

Deep into that darkness peering, long I stood there wondering, fearing,
Doubting, dreaming dreams no mortal ever dared to dream before;
But the silence was unbroken, and the darkness gave no token,
And the only word there spoken was the whispered word, `Lenore!'
This I whispered, and an echo murmured back the word, `Lenore!'
Merely this and nothing more.

Back into the chamber turning, all my soul within me burning,
Soon again I heard a tapping somewhat louder than before.
`Surely,' said I, `surely that is something at my window lattice;
Let me see then, what thereat is, and this mystery explore -
Let my heart be still a moment and this mystery explore; -
'Tis the wind and nothing more!'

Open here I flung the shutter, when, with many a flirt and flutter,
In there stepped a stately raven of the saintly days of yore.
Not the least obeisance made he; not a minute stopped or stayed he;
But, with mien of lord or lady, perched above my chamber door -
Perched upon a bust of Pallas just above my chamber door -
Perched, and sat, and nothing more.

Then this ebony bird beguiling my sad fancy into smiling,
By the grave and stern decorum of the countenance it wore,
`Though thy crest be shorn and shaven, thou,' I said, `art sure no craven.
Ghastly grim and ancient raven wandering from the nightly shore -
Tell me what thy lordly name is on the Night's Plutonian shore!'
Quoth the raven, `Nevermore.'

Much I marvelled this ungainly fowl to hear discourse so plainly,
Though its answer little meaning - little relevancy bore;
For we cannot help agreeing that no living human being
Ever yet was blessed with seeing bird above his chamber door -
Bird or beast above the sculptured bust above his chamber door,
With such name as `Nevermore.'

But the raven, sitting lonely on the placid bust, spoke only,
That one word, as if his soul in that one word he did outpour.
Nothing further then he uttered - not a feather then he fluttered -
Till I scarcely more than muttered `Other friends have flown before -
On the morrow he will leave me, as my hopes have flown before.'
Then the bird said, `Nevermore.'

Startled at the stillness broken by reply so aptly spoken,
`Doubtless,' said I, `what it utters is its only stock and store,
Caught from some unhappy master whom unmerciful disaster
Followed fast and followed faster till his songs one burden bore -
Till the dirges of his hope that melancholy burden bore
Of "Never-nevermore."'

But the raven still beguiling all my sad soul into smiling,
Straight I wheeled a cushioned seat in front of bird and bust and door;
Then, upon the velvet sinking, I betook myself to linking
Fancy unto fancy, thinking what this ominous bird of yore -
What this grim, ungainly, ghastly, gaunt, and ominous bird of yore
Meant in croaking `Nevermore.'

This I sat engaged in guessing, but no syllable expressing
To the fowl whose fiery eyes now burned into my bosom's core;
This and more I sat divining, with my head at ease reclining
On the cushion's velvet lining that the lamp-light gloated o'er,
But whose velvet violet lining with the lamp-light gloating o'er,
She shall press, ah, nevermore!

Then, methought, the air grew denser, perfumed from an unseen censer
Swung by Seraphim whose foot-falls tinkled on the tufted floor.
`Wretch,' I cried, `thy God hath lent thee - by these angels he has sent thee
Respite - respite and nepenthe from thy memories of Lenore!
Quaff, oh quaff this kind nepenthe, and forget this lost Lenore!'
Quoth the raven, `Nevermore.'

`Prophet!' said I, `thing of evil! - prophet still, if bird or devil! -
Whether tempter sent, or whether tempest tossed thee here ashore,
Desolate yet all undaunted, on this desert land enchanted -
On this home by horror haunted - tell me truly, I implore -
Is there - is there balm in Gilead? - tell me - tell me, I implore!'
Quoth the raven, `Nevermore.'

`Prophet!' said I, `thing of evil! - prophet still, if bird or devil!
By that Heaven that bends above us - by that God we both adore -
Tell this soul with sorrow laden if, within the distant Aidenn,
It shall clasp a sainted maiden whom the angels named Lenore -
Clasp a rare and radiant maiden, whom the angels named Lenore?'
Quoth the raven, `Nevermore.'

`Be that word our sign of parting, bird or fiend!' I shrieked upstarting -
`Get thee back into the tempest and the Night's Plutonian shore!
Leave no black plume as a token of that lie thy soul hath spoken!
Leave my loneliness unbroken! - quit the bust above my door!
Take thy beak from out my heart, and take thy form from off my door!'
Quoth the raven, `Nevermore.'

And the raven, never flitting, still is sitting, still is sitting
On the pallid bust of Pallas just above my chamber door;
And his eyes have all the seeming of a demon's that is dreaming,
And the lamp-light o'er him streaming throws his shadow on the floor;
And my soul from out that shadow that lies floating on the floor
Shall be lifted - nevermore!

copied by: viel alojado