Dermatology Made Simple : Psoriasis : Patterns of Joint Involvement in Psoriasis:

Patterns of Joint Involvement in Psoriasis:

There are Five patterns of Joint involvement in Psoriatic arthropathy:

1.      Distal Interphalangeal Joint Involvement:

2.       Asymmetrical Oligoarticular Joint Involvement

3.       Symmetrical Polyarthritis

4.       Arthritis Mutilans

5.       Spondylitis

Psoriatic Arthropathy affects 5 – 10 % of patients with psoriasis.

In most cases patients develop skin manifestations of psoriasis before joint involvement occurs.

Distal Interphalangeal Joint Involvement:

This is the most common pattern of arthropathy in Psoriasis.

This is usually asymmetrical.

It affects both males and females equally.

Arthritis Mutilans:

This is the most severe although rarest form of Psoriatic arthropathy.

It is characterized by considerable bone resorption and subsequent telecscoping of fingers.

Mathematic Made Simple: Sets

Set:

A set is a collection of distinct and well defined objects.

The objects of which a set consists of are called its elements.

Representation of a Set:

A set is usually denoted by capital English Letters:

Eg A,B,C

A set is mainly represented in three ways

1.Tubular Method:

The members of a set are written within braces , for example:

A = ( 1,2,3,4,5,6,7)

2.Descriptive Method:

The members of a set are described in words  with regards to a common attribute in them for example

A = A set of natural numbers from 1 to 7

3.Set Builder Notation:

We use symbols to describe this set for example

.A = ( x I x is a natural number, 1   < x < 7 )

This can be explained as A is a set of all x such that xis a natural number from 1 to 7.

Common types of sets:

N = Set of natural numbers = ( 1,2,3,4,…….)

W= Set of whole numbers= (0,1,2,3,4,……..)

Z = Set of integers

Z+ Set of positive integers

Z- The set of negative integers

P= set of prime numbers = (2,3,5,7,11,13,……)

E = set of even integers

O Set of odd integers

Q = set of rational numbers

Computer Studies Made Simple : Types of ROM / Read only Memory

Types of ROM / Read only Memory

1.PROM / Programmable Read Only Memory

This form of ROM is initially blank.

The user or manufacturer can write data and programmes on it using special devices.

The user can write data and instructions on it only once.

If there is an error in writing these instructions,the error cannot be removed from it and the chip becomes 

unusable.

2.EPROM/ Erasable Programmable Read Only memory:

This form of ROM is again initially blank.

The user or manufacturer can write data and programmes on it using special devices.

The data and programmes written on it can be erased with special devices using ultraviolet rays.

The user can write new programmes on it as well.

3.EEPROM / Electronically Erasable Programmable Read  Only memory:

In this memory,user can erase and write instructions with the help of electrical pulses.

If there is any error in writing instructions,the user can erase the contents electronically.

The contents of EEPROPM canbe modified easily.  

Nephrology Made Simple : Metabolic Complications of Renal Failure:

Metabolic Complications of Renal Failure:

Lipid Abnormalities:

Renal failure leads to an increase in plasma cholesterol levels.

This leads to deposition of cholesterol in blood vessels and an increased incidence of cardiovascular complications and renal vascular disease.

This is usually present in patients with heavy proteinuria.

In patients without proteinuria,there is an increase in serum triglyecerides and abnormal apolipoprotein metabolism.

Acidosis:

This occurs in severe renal failure.

It results in bone disease,increased muscle metabolism and growth retardation in children.

In severe casese,it causes hyperventilation and also predisposes to hyperkalemia.

HYPERKALEMIA

This occurs in Chronic renal failure and has a number of causes

Causes of Hyperkalemia in Renal Failure :

1.Decreased secretion in collecting ducts :

Mostly due to medications :

Spironolactone

ACE inhibitors

Angiotensin 2 receptor blockers

Hyporeninaemic hypoaldosteronism

2.Decreased renal excretion :

Potassium sparing diuretics

Worsening renal failure

3.Shift of potassium from cells:

Acidosis

Muscle breakdown

Released from red blood cells after transfusion

4 Increased potassium intake :

Dietry intake

Potassium supplements : Oral or iv

Absorption from blood : Haematoma or GI bleed

Computer studies Made Simple : Types of Computer Memory

Types of Memory:

Memory has two types:

1.RAM

2.ROM

1.RAM / Random access memory:

Also known as Direct Access Memory

In this type of memory,each individual byte in entire memory canbe accessed directly.

This is a temporary memory.

When the power is turned off,all the information in the RAM is lost.

It is also called as volatile memory.

CPU can read data from RAM and write data to RAM as well.

RAM is also called as read write memory.

It is used to store data and instruction while it is being executed.

RAM is also called as Main Memory or primary storage.

2.ROM/Read Only Memory:

The instructions I ROM prepare the computer for use.

These instructions can only be read but cant be altered or deleted.

It isnot possible to write new information or instructions into the ROM.

ROM stores data and instructions permanently.

When the power is turned off,the memory in ROM isnot lost and hence is called as non-volatile memory.

The information on ROM is stored by manufacturer and hence,when the power is switched on,the instructions in ROM are loaded into the memory of computer.  

Types Of RAM

RAM is built by using two different techniques:

A.      DRAM :

DRAM / Dynamic Random Access Memory:

This type of memory is used in most computers.

It is most economic type of RAM.

It requires an electric current to maintain its electric state.

The electric charge on DRAM decreases with time and this may result in loss of data.

DRAM has to be recharged over and over again to maintain its data retaining capabilities.

It has slower performance because the processor cannot acces its data while its being recharged.

B.      SRAM

SRAM /Static Random Access Memory :

The memory cells are made from digital gates.

Each cell can store its value without any read to refresh the data as long as the power is available.

SRAM is relatively more expensive.

CPU can access data readily as it doesnot need to be recharged to maintain its performance,hence its faster.

It uses more power than DRAM and canbe used to build a very fast emory called as Cache memory  

Nephrology Made Simple : End Stage Renal Disease : Signs and symptoms

Clinical features of End Stage Renal Disease:

General Physical Examination:

Anemia

Skin bruises

Scratch marks on skin

Postural hypotension

Peripheral oedema

Corneal calcification

Cardiovascular System:

Left ventricular hypertrophy

Arterial bruits

Peripheral vascular disease

Respiratory System:

Lung crackles

Pleural effusions

Abdomen / GIT

Abdominal scars

Palpable kidneys or Liver ( in polycystic disease)

Nervous system:

Peripheral neuropathy

Proximal Myopathy

Symptoms:

Loss of appetitie

Weakness

Fatigue

Nausea

Lethargy

Loss of sleep

Increased tendency to bleed

Restless legs

Sexual dysfunction

Nephrology made Simple : End Stage Renal Disease

End Stage Renal Disease:

This is defined as loss of function of the kidney to such an extent that requires treatment with either long term dialysis or renal transplantation

Causes of End Stage Renal Disease:

1.Diabetes Mellitus:

This is the most common cause of ESRD in Western countries.

2.Arterial Pathology:

Diseases that can cause longterm  arterial/vascular pathology in the kidney include :

Hypertension.

Malignant Hypertension.

Renal artery stenosis.

3.Infections of kidney:

This includes

Glomerulonephritis.

Pyelonephritis.

Tuberculosis.

HIV.

4.Obstructive uropathy

5.Reflux uropathy

6..Toxins:

Such as:

Lead

Cadmium

Lithium

Cyclosporin

7.Familial Diseases:

Polycystic kidney disease

Fabry”s disease

Oxalosis

Tuberous sclerosis

Cystinosis

Alport”s disease

8.Other causes:

Interstitial nephritis

Radiation nephritis

Sickle cell disease

Sarcoidosis

Traumatic Renal Loss

Computer Studies Made Simple : Main Memory:

Main Memory:

This is an important component of a computer system.

It is used to store programme and data that are being used.

It is also known as the working area of computer system.

A computer cannot work without its main memory.

Structure of Main Memory:

The main memory is bult in the form of a chip.

The chip is made up of a semi-conductor material.

The chip consists of thousand or millions of cells.

Each cell can store one bit as 0 or 1.

The cells in main memory are organized as groups of 8 bits.

One group of 8 bits is known as byte.

Each byte in the memory is assigned a unique number.

This number is called as the address of the byte.

Accessing data in main memory:

Main memory is a sequence of bytes.

CPU and other components can access any byte of main memory by specifying its address.

Different bytes canbe accessed randomly.Accessing any part of memory takes equal time.

Accessing data from the main memory doesnot require any form of movement.

That is why main memory is very fast as compared to other storage devices such as Magnetic disc.  

Rheumatology Made Simple : Neck Pain

Neck Pain:

Neck pain is a fairly common symptom.

Usually it accompanies thoracis spine pathology.

It may be associated with degenerative changes in cervical spine such as intervertebral disc narrowing,osteophyte formations at end plates and erosion of facet joints.

At a given time,around 12 % of population will be having neck pain.

Causes Of Neck Pain:

1.Inflammatory Diseases:

Rheumatoid arthritis

Polymyalgia rheumatica.

Juvenile idiopathic arthritis.

2.Infectious diseases:

Brucellosis

3.Soft tissue pathology:

Trauma

Whip lash injury

Neck strain

4.Degenerative Bone disorders:

Disc proplapse

Osteoporosis

Traumatic fracture

Osteomyelitis

Osteomalacia

Paget”s disease

5.Trauma

Direct to the neck

Bracial plexus trauma

6.Referred pain:

From Shoulder as in adhesive capsulitis

From pharynx eg in pharyngitis / infections.

Temporomandibular joint and Acromioclavicular joint

Dermatology Made Simple : Psoriasis : Clinical Presentation:

Psoriasis : Clinical Presentation:

Usually,the patients present with plaques on the elbows,knees, and scalp.

Lesions on the  trunk are usually annular.

Psoriatic lesions may develop in scars and areas of minor skin trauma,this is called as Koebner”s phenomenon.

Scales may develop on scalp in 50 % of patients.

There may be small pits on the nails and separation of nail from nail bed can occur,a process called as Onycholysis

Guttate Psoriasis:

This consists of widespread small plaques scattered on the trunk and limbs.

It is usualy preceded by a Gp B haemolytic streptococcal pharyngitis and affects adolescents mostly.

There is a family history in most of cases.

In most cases,it resolves completely.

There may be history of recurrence.

Pustular psoriasis:

This occurs as chronic deep seated lesions on the palms and soles.

Scales develop in most of the cases and there is a surrounding erythema as well.

There is a known association with smoking.

Severe form of psoriasis may be associated with generalized pustular psoriasis.

It maybe precipitated by the use of oral steroids.

Flexural Psoriasis:

This produces well – defined erythematous areas in the axillae,groin and natal cleft,beneath the breasts and in skin folds.

Scaling is minimum and maybe absent.

Erythrodermic Psoriasis:

This is a serious and sometimes life threatening condition with confluent erythema affecting nearly all of the skin.

Characteristic scaling of psoriasis may be absent.

It may lead to heat and water loss.

Patients should be hospitalized.

Computer Studies Made Simple : Computer Architecture

Computer Architecture:

A computer is a combination of various components each of which perform different functions.

These components work together and communicate with each other.

The way in which these computers are connected with each other is called computer architecture.

Components of a computer:

Different components of a computer are as follows:

1.Control Unit:

Control unit is an important component of CPU.

It acts as a supervisor of computer and controls all activities of a computer.

It performs the following operations:

a.It carries instruction from main memory.

b.Interprets instruction to find what operation needs to be performed.

c.Controls execution of instruction.

2.Arithmetic Logic Unit:

This is a part of CPU.

In this part,actual execution of instructions takes place.

All arithmetic and logical operations are performed in ALU.

It consists of two units:

a.Arithmetic Unit:

This performs basic arithmetic functions like : Additio,subtraction,multiplication and division.

b.Logic Unit:

It performs logic operations like : comparing two data items to find which data is greater than equal to or less than the other.

3.Main Memory:

This is an important component of computer system.

It is used to store programme and data that are being executed.

It is also called as working area of a computer system.

4. I/O Unit:

I/O unit controls processor”s communicatiosn with peripheral devices such as monitor,disk drive and printer connected to the computer system.

5.BUS interconnection:

It is an important component of a computer system.

A computer system onsists of a CPU,Main memory and I/O Units.

These components have to be connected to transfer data from one component to another.

The use of buses to connect different components is known as Bus interconnection.

Physics Made Simple : Refraction through a prism:

Refraction through a prism:

Prism is a transparent body having three rectangular and two triangular surfaces.

The angle of the triangular surface opposite the base is known as Angle of Prism.

If an incident ray PQ strikes prism on surface AB,on entering the prism,the ray bends towards the normal at its point of incidence Q.,ie towards the base of the prism.

The refracted ray QR on coming out of the prism bends away from the normal RN at the point of emergence R ie the emergent ray RS bends towards the base of the prism.

The incident ray PQ makes an angle of incidence I and r is its corresponding  angle of refraction of the prism.

If n is the refractive index of the prism,

N = sin i/ sin r

The original direction of incidenr ray is PQT but it is turned through angle TDS on passing through the prism.

The angle TDS is known as the Angle of deviation.

THE VALUE OF ANGLE OF DEVIATION DEPENDS UPON THE VALUE OF ANGLE OF INCIDENCE.

When the angle of incidence is continuously increased from a small value,the angle of deivation first decreases,reaches a minimum value and then starts increasing.

The minimum value of angle of deviation is known as the angle of minimum deviation and is denoted by Dm.

The refractive index “n” of the material of the prism with respect to air canbe determined by the following relation:

N = Sin ( A + Dm/2) / sin(A/2)

Where A is angle of the prism and Dm is the angle of minimum deviation.

The refraction of waves depends on their wavelengths.Since sunlight consists of different colours,the waves of different wavelengths,thus when it passes through a prism,then the waves of different wavelengths deviate on different paths due to this white light disperses in different colours,which is called as dispersion and the band of colours which is seen on the screen is called solar spectrum.  

A ray trace through a prism with apex angle α. Regions 0, 1, and 2 haveindices of refraction , , and , and primed angles  indicate the ray angles after refraction.

Types of prisms

Dispersive prisms

Comparison of the spectra obtained from a diffraction grating by diffraction (1), and a prism by refraction (2). Longer wavelengths (red) are diffracted more, but refracted less than shorter wavelengths (violet).

Dispersive prisms are used to break up light into its constituent spectral colors because the refractive index depends on frequency; the white light entering the prism is a mixture of different frequencies, each of which gets bent slightly differently. Blue light is slowed down more than red light and will therefore be bent more than red light.

• Triangular prism
• Abbe prism
• Pellin–Broca prism
• Amici prism
• Compound prism
• Grism, a dispersive prism with a diffraction grating on its surface

Reflective prisms

Reflective prisms are used to reflect light, in order to flip, invert, rotate, deviate or displace the light beam. They are typically used to erect the image inbinoculars or single-lens reflex cameras – without the prisms the image would be upside down for the user. Many reflective prisms use total internal reflection to achieve high reflectivity.

The most common reflective prisms are:

• Porro prism
• Porro–Abbe prism
• Amici roof prism
• Pentaprism and roof pentaprism
• Abbe–Koenig prism
• Schmidt–Pechan prism
• Bauernfeind prism
• Dove prism
• Retroreflector prism

Beam-splitting prisms

Some reflective prisms are used for splitting a beam into two or more beams:

• Beam splitter cube
• Dichroic prism

Polarizing prisms

There are also polarizing prisms which can split a beam of light into components of varying polarization. These are typically made of a birefringent crystalline material.

• Nicol prism
• Wollaston prism
• Nomarski prism – a variant of the Wollaston prism with advantages in microscopy
• Rochon prism
• Sénarmont prism
• Glan–Foucault prism
• Glan–Taylor prism
• Glan–Thompson prism

Deflecting prisms

Wedge prisms are used to deflect a beam of light by a fixed angle. A pair of such prisms can be used for beam steering; by rotating the prisms the beam can be deflected into any desired angle within a conical "field of regard". The most commonly found implementation is a Risley prism pair. Two wedge prisms can also be used as an anamorphic pair to change the shape of a beam. This is used to make a round beam from the elliptical output of a laser diode.

Rhomboid prisms are used to laterally displace a beam of light without inverting the image.

Deck prisms were used on sailing ships to bring daylight below deck, since candles and kerosene lamps are a fire hazard on wooden ships.

Deviation angle and dispersion

A ray trace through a prism with apex angle α. Regions 0, 1, and 2 haveindices of refraction , , and , and primed angles  indicate the ray angles after refraction.

Ray angle deviation and dispersion through a prism can be determined by tracing a sample ray through the element and using Snell's law at each interface. For the prism shown at right, the indicated angles are given by

.

For a prism in air . Defining , the deviation angle  is given by

If the angle of incidence  and prism apex angle  are both small,  and  if the angles are expressed in radians. This allows the nonlinear equation in the deviation angle  to be approximated by

The deviation angle depends on wavelength through n, so for a thin prism the deviation angle varies with wavelength according to

.

Physics Made Simple : Total Internal Reflection

Total Internal Reflection

When a ray of light passes from a denser medium (glass) to a rarer medium (air),the refracted ray bends away from the normal and the angle of refraction is greater than the angle of incidence.

As the angle of incidence I increases,the anlge of refraction r also increases in a way that r is always greater than i.till for a particular value of angle of incidence,the corresponding angle of refraction become 90 degrees and the refracted ray grazes along the surface.

“The angle of incidence in the denser medium for which the corresponding angle of refraction is 90 degrees in the rarer medium is called the critical angle”C”.

This angle of incidence/Critical angle is denoted by “C”  .

When the value of the angle of incidence becomes greater than the critical angle,then the ray does not pass into the second medium (air),that is the ray of light no longer undergoes refraction,but are totally reflected back in the denser medium eg (glass) obeying the laws of reflection.

Such reflection of light is termed as “Total Internal Reflection”.

There are two conditions that must exist for total internal reflection:

1.The ray of light should travel from a denser medium to a rare medium.

2.The angle of incidence should be greater than the critical angle.   

  

Critical Angles of Different Materials:

Glass                                     42 degrees

Water                                   49 degrees

Diamond                              24 Degrees

1.Total internal reflection can be seen at the air-water boundary.





2.Total internal reflection in a block of acrylic



3.Total internal reflection in a semi-circular acrylic block

Images from Wikipedia

Computer Studies Made Simple : Internet :Key Terms

E-mail:

This stands for electronic mail.

Email means exchange of messages and files through internet.

Messages canbe in the form of graphics,sounds,video clips or simple text.

It is a fast way of sending messages in a very short time anywhere in the world.

Web site:

A collection of related web pages is called a website.

Each website has a unique address.

It contains text,graphics,sound and video.

Internet Service Provider / ISP:

This refers to a company that provides internet connections.

ISP also provides facilities of Email.

A connection from ISP is necessary to connect to the internet.

Web browsing:

This is a process of searching information on the world wide web.

A software used to search and view web pages is known as a web browser.

An example of web browser include Internet explorer and google chrome.





Internet packet routing is accomplished among various tiers of Internet service providers.






This NeXT Computer was used by Tim Berners-Lee at CERN and became the world's first Web server.

Dermatology Made Simple : Psoriasis : Causes

Causes of Psoriasis

Psoriasis is an autoimmune skin disease with an inherited genetic predisposition and immunological triggers.

A psoriasis susceptibility locus PSORS1 is identified on chromosome 21 within the MHC : major Histo Compalibility Complex.

In 60 % of patients,HLA-CW6 is the phenotype associated with Psoriasis especially in patients with early onset disease.

HLA types associated with Psoriatic arthropathy include : HLA B27,B17,CW6,DR4 and DR7.

Trigger factors for Psoriasis:

Certain form of Psoriasis maybe triggered by :

Immunological stimuli such as Beta Hemolytic streptococcal infections.

Certain Drugs:

Antimalarials

Lithium

Beta blockers.

Other factors include:

Local trauma

General illness

Stress

High intake of alcohol

Smoking

Histological changes:

There is increased T cell activity in diseased skin.

The activated T cells lead to high levels of pro-inflammatory cytokines in psoriatic lesions especially gamma interferon and TNF : Tumor Necrosis Factor alpha.

TNF alpha increases keratinocyte proliferation and induces SKALP/elafin gene which is not expressed in normal keratinocytes.

This gene is a marker of abnormal keratinocyte differentiation,a hyperproliferative epidermis and increased inflammation.

The cellular abnormalities found in psoriatic plaques are targeted by some of the novel biological therapies.

TNF alpha blockers include etanercept and infliximab.

T cell blockers include efalizumab and alefacept.

Dermatology Made Simple : Psoriasis : Clinical Lesions and Trigger Factors

Clinical Lesions in Psoriasis:

Usually, a patient with psoriasis will have the following clinical lesions:

1.Plaques:

These are well defined raised lesions.

They may be variable ie large or small,few or extensive,over arms legs or trunk.

2.Scaling:

This is a chatacteristic feature of Psoraisis.

There are silver plaques on the plaques.

3.Redness/Erythema:

The affected skin will be markedly erythematous/red.

This may be more marked in body flexures such as groin and axillae (Arm pits).

4.Pustules:

Pustules may occasionally be seen in Psoriasis.

Factors Affecting Psoriasis:

1.Age:

Most commonly,first presentation is around 27 years,however the age of onset is variable and can affect at any age from infancy to old age

2.Familiy History:

There is an increased incidence of Psoriasis in offspring of affected parent.

3.Infections:

Infection of any type can trigger the onset of psoriasis.

4.Stress:

It has been noted that any type of stress can also enhance or trigger psoriaisis in predisposed individuals.

5.Trauma:

In predisposed individuals,lesions may develop at sites of trauma on the skin.In this case term used is 

Koebner”s phenomenon.

1.Pustular Psoriasis

2.Nail Psoriasis





3.Plaque Psoriasis





4.Guttate Psoriaisis





5.Scalp Psoriasis

Images from Healthline.com

Computer Studies Made Simple : World Wide Web and Search Engines

World Wide Web (WWW):                 

World Wide web is a collection of documents stored in computers that can be accessed using internet.It is a means of providing information on computers using the internet.

As already discussed,internet refers to collections of lot of computers around the world that are connected to each other by different telecommunications links such as phone lines,wireless and fibreoptics etc.

Search Engines:

This refers to a website that can be used to obtain information on any topic by the user.

Sometimes it may be difficult to remember a website address and in this case most easy way out is to search about a topic on the searh engine and we can get relevant information on that topic.

Some of the commonly used Search Engines include:

Google

Yahoo

Lycos

Alta Vista  

Physics Made Simple : Light : Refraction : Properties of Refraction and Refractive Index

Refraction

When a ray of light travelling in one medium enters another medium,it bends away from its path.

This bending of waves from their path is called Refraction.

Refraction occurs due to change in speed of light in the other medium.

Laws Of Refraction:

There are two main laws of refraction:

1.The incident ray,the refracted ray and the normal at the point of incidence all lie in the same plane.

2.When a ray of light passes from one particular medium to another,the ratio of the sine of angle of incidence i to sine of angle of refraction r is a constant.

This constant ratio is called the Refractive Index of the second medium with respect to (w.r.t) the first and is denoted by letter n

 n = sin I / sin r

The refractive Indext can also be calculated by dividing the speed of light in vacuu by the speed of light in that medium.

As the speed of light in vacuum is almost equal to speed of light in air,we can use speed of light in air instead of speed in vacuum.

Refractive Indices of Various substances:

Medium                                                  Refractive Index

Air                                                          1.003

Vacuum                                                  1.000

Water                                                    1.33

Ice                                                         1.30

Diamond                                                2.42

Glycerine                                               1.47

Alcohol                                                  1.36

Dermatology Made Simple : Psoriasis : Definition Pathogenesis and Risk Factors

Psoriasis:

Psoriasis is a dermatological disease that has a variety of clinical types.

It has a genetic component and a number of exacerbating factors.

Nail changes and arthropathy may be associated in a number of cases.

Risk factors that can predispose to psoriasis include :

Hormonal Changes.

Stress

Infection

Pathogenesis:

Keratinocytes are skin cells that predominate in the epidermis,they grow from bottom/basal layer and slowly migrate to the surface.

In normal skin,this process of turnover usually takes 23 days.In patienst with psoriasis,cell turnover is rapidly accelerated taking only 3-5 days for cells to reach the surface and accumulate in large numbers.

This leads to one of characteristic features of psoriasis namely thickened skin due to scaling (hyperkeratosis).
Keratinocytes usually lose their nucleus as they move to the skin surface,In psoriasis however,they move so quickly that cell retain their nucleus throughout the epidermis.

Nail Involvement:

In a patient with psoriasis,nail involvement occurs and may have the following changes:

Onycholysis:

This means lifting of nail plate off the nail bed.

Sub-ungal hyperkeratosis:

Excessive proliferation of nail bed tissue.

Pitting:

Very small depressions in the nail plate.

Beau”s Lines:

Transverse lines on the nail plate.

Splinter haemorrhages:

Longitudinal black lines on nail

Computer studies Made Simple : Web browsing World Wide Web and Web Server

Web browsing:

This is a term used to describe process of sharing information on the world wide web.

A software used to search and view web pages is known as web browser.

A web can act as an interface between the user and the internet.It can display text and graphics.

The browser contacts a web server and sends a request for the required information.

The web server searches for the requested web page and sends it to the web browser.

The browser receives the information and then displays it on the user”s computer.

World Wide Web:

The word wide web / www provides the facility to publish information on the internet.

It is a collection of documents or web pages stored on computers permanently connected with internet around the world.

A web page is a document written in HTML.

These web pages are connected to each other using hyperlinks..

The www uses Hypertext transfer protocol / http to link these web pages.

Web pages are also known as hypertext documents.

A web page may contain a simple text,images and hyperlinks.

Anyone can view web pages through a web browser.

A collection of related web pages is called website.

Each website has a unique address.

Websites are stored on a host computer on the internet.

These computers are known as web server.

The process of launching a web page is called as publishing the page.