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Internet


Internet

A.  Pengertian
Internet singkatan dari Interconnected Network. Internet adalah kumpulan komputer yang terhubung satu dengan yang lain dalam sebuah jaringan.
Internet mempunyai peranan yang sangat penting        :
a.     Sebagai sumber data dan informasi
Internet menyimpan berbagai jenis informasi dalam jumlah yang tidak terbatas,siapa saja dapat mengakses berbagai informasi.
b.     Sarana pertukaran data dan informasi
Internet dapat digunakan sebagai sarana pertukaran informasi dari satu komputer ke komputer lain tanpa dibatasi oleh jarak fisik kedua komputer tersebut. Dua komputer yang sama-sama terhubung dapat saling berkomunikasi satu sama lain, mempertukarkan data dan informasi dalam waktu yang sangat cepat.

        I.            Sejarah
          Pada tahun 1969 ARPA (Advanced Research Project Argency) milik Departemen Pertahanan Amerika Serikat membuat sebuah jaringan bernama ARPAnet yang digunakan untuk keperluan penelitian. Jaringan tersebut kemudian juga dipergunakan untuk keperluan penelitian oleh Perguruan Tinggi, dimulai oleh University of  California, Stanford Research Institute dan University of  Utah. Sejak saat itu penggunaan internet meluas meski dalam kalangan terbatas. Pada tahun 1986 internet kemudian dipergunakan secara terbuka untuk umum.
     II.            Berbagai Aplikasi Internet
Dari sekian banyak aplikasi internet yang ada saat ini, yang paling banyak dikenal dan digunakan, antara lain   :

Ø World Wide Web
World Wide Web atau www merupakan aplikasi yang paling banyak digunakan dan merupakan aplikasi yang paling penting.
WWW adalah dokumen-dokumen internet yang disimpan di server-server yang terdapat diseluruh dunia. Dokumen web tersebut dibuat dengan menggunakan format hypertext dan hypermedia, yaitu Hypertext Markup Language (HTML). HTML mempunyai kemampuan untuk menghubungkan (link) sebuah dokumen dengan dokumen yang lain. Dokumen yang dibuat dengan HTML tersebut dapat memuat teks, gambar, animasi, audio, dan video.
Ø Electronic Mail (E-mail)
E-mail atau surat elektronik adalah aplikasi internet untuk sarana komunikasi surat-menyurat dalam bentuk elektronik. Melalui e-mail, kita juga dapat mengirimkan file dokumen, gambar, dan sebagainya.
E-mail merupakan alat komunikasi yang murah dan cepat. Kita dapat mengirimkan surat keseluruh dunia dengan biaya yang sangat murah.
Ø Mailing List
Mailing List atau sering juga disebut milis adalah aplikasi internet yang digunakan sebagai sarana diskusi atau bertukar informasi dalam satu kelompok melalui e-mail. Milis sebenarnya bentuk lain dari e-mail. Fasilitas ini digunakan oleh kelompok-kelompok untuk bertukar informasi dan berdiskusi sesama anggota kelompok. Milis mempunyai sifat yang sama dengan e-mail.
Ø Newsgroup
Newsgroup adalah aplikasi internet yang digunakan untuk berkomunikasi satu sama lain dalam sebuah forum. Sarana yang mungkin digunakan dalam newsgroup dapat berupa multimedia (audio-visual) dengan menggunakan fasilitas konferensi video, dapat berupa teks aja atau teks dan audio dengan menggunakan fasilitas chat (IRC).
Ø Internet Relay Chat
IRC adalah aplikasi internet yang digunakan untuk bercakap-cakap di internet. Bercakap-cakap di internet dikenal dengan istilah chatting. Dengan menggunakan fasilitas ini, kita dapat “bercakap-cakap” sambil melihat gambar orang yang sedang chatting dengan kita.

Ø File Transfer Protocol
File Transfer Protocol yang sering disingkat dengan FTP adalah aplikasi internet yang digunakan untuk mengirimkan atau mengambil file ke / dari komputer lain. FTP sering digunakan untuk mencari dan mengambil (download) arsip (file) dari sebuah server di internet yang mempunyai alamat tertentu yang menyediakan berbagai file.
Ø Telnet
Telnet adalah aplikasi internet yang digunakan untuk mengakses komputer yang letaknya jauh. Telnet dapat digunakan apabila kita mempunyai alamat IP (IP address) dari komputer  yang akan diakses dan kita juga harus mempunyai hak akses (user ID dan password) ke komputer tersebut.
Ø Gopher
Gopher adalah aplikasi yang digunakan untuk mencari informasi yang ada di internet. Untuk mendapatkan informasi melalui Gopher, kita harus menghubungkan diri dengan Gopher server yang ada di internet.
Ø Ping
Ping adalah singkatan dari Packet Internet Gopher. Ping digunakan untuk mengetahui apakah komputer yang kita gunakan terhubung (terkoneksi) dengan komputer lain di internet.
 III.             Kegunaan internet   :
a.     Sarana untuk mendapatkan dan menyampaikan informasi yang cepat dan murah.
b.     Mengurangi biaya kertas dan biaya distribusi.
c.      Sebagai media promosi
d.     Sarana komunikasi interaktif
e.      Sarana penelitiaan dan pengembangan (Research dan Development)
f.       Sarana untuk mempertukarkan data

B. Dasar-dasar Sistem Jaringan di Internet
Jaringan Komputer adalah sebuah system yang terdiri atas komputer dan perangkat jaringan lainnya yang bekerja bersama-sama untuk mencapai suatu tujuan yang sama.

Tujuan dari jaringan komputer adalah :
·        Membagi sumber daya
·        Komunikasi
·        Akses informasi

1.     Cara menghubungkan komputer dengan internet
a.     Melalui Jaringan
b.     Melalui Saluran Telepon Langsung (Dial Up)
c.      Menggunakan Jaringan GPRS
d.     Melalui WiFi
e.      Menggunakan Jaringan TV Kabel
f.       Menggunakan Wireless Broadband
2.     Macam-macam Jaringan
a.     Berdasarkan skala
·        Local Area Network (LAN)
·        Metropolitant Area Network (MAN)
·        Wide Area Network (WAN)
·        Internet
·        Jaringan tanpa kabel
b.     Berdasarkan fungsi
c.      Berdasarkan topologi jaringan

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Price Tag lyrics
Songwriters: Jessica Cornish;Lukasz Gottwald;Claude Kelly;Jr. Simmons Lyrics

Featuring: B.O.B.

Seems like everybody's got a price
I wonder how they sleep at night
When the sale comes first and the truth comes second
Just stop for a minute and smile

Why is everybody so serious?
Acting so damn mysterious
You got your shades on your eyes and your heels so high
That you can't even have a good time

Everybody look to their left
Everybody look to their right
Can you feel that? Yeah
We'll pay them with love tonight

It's not about the money, money, money
We don't need your money, money, money
We just wanna make the world dance
Forget about the price tag

Ain't about the cha-ching, cha-ching
Ain't about the ba-bling, ba-bling
Wanna make the world dance
Forget about the price tag

We need to take it back in time
When music made us all unite
And it wasn't low blows and video hoes
Am I the only one gettin' tired?

Why is everybody so obsessed?
Money can't buy us happiness
Can we all slow down and enjoy right now
Guarantee we'll be feelin' alright

Everybody look to their left
Everybody look to their right
Can you feel that? Yeah
We'll pay them with love tonight

It's not about the money, money, money
We don't need your money, money, money
We just wanna make the world dance
Forget about the price tag
(From: http://www.elyrics.net/read/j/jessie-j-lyrics/price-tag-lyrics.html)

Ain't about the cha-ching, cha-ching
Ain't about the ba-bling, ba-bling
Wanna make the world dance
Forget about the price tag

Yeah, yeah, well, keep the price tag and take the cash back
Just give me six strings and a half stack
And you can keep the cars, leave me the garage
And all I, yes, all I need are keys and guitars

And guess what, in 30 seconds I'm leaving to Mars
Yes, we leaving across these undefeatable odds
It's like this man, you can't put a price on life
We do this for the love, so we fight and sacrifice every night

So we ain't gon' stumble and fall, never
Waiting to see, a sign of defeat, uh uh
So we gon' keep everyone moving their feet
So bring back the beat and then everybody sing, it's not about

It's not about the money, money, money
We don't need your money, money, money
We just wanna make the world dance
Forget about the price tag

Ain't about the cha-ching, cha-ching
Ain't about the ba-bling, ba-bling
Wanna make the world dance
Forget about the price tag

It's not about the money, money, money
We don't need your money, money, money
We just wanna make the world dance
Forget about the price tag

Ain't about the cha-ching, cha-ching
Ain't about the ba-bling, ba-bling
Wanna make the world dance
Forget about the price tag

Yeah, yeah
Oh, forget about the price tag

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Venereal Disease Research Laboratory test

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VDRL slide for performing the blood test for Syphilis
The Venereal Disease Research Laboratory test or VDRL is a blood test for syphilis and was developed by the former Venereal Disease Research Laboratory, now the Treponemal Pathogenesis and Immunology Branch, of the United States Public Health Service. The VDRL type test was invented before World War I, with its first iteration being that developed by August Paul von Wasserman with the aid of Albert Neisser in 1906.

History

The VDRL test, as it is largely still done today, was developed in 1946 by Harris, Rosenberg, and Riedel.[1]

Mechanism

The (VDRL) is a nontreponemal serological screening for syphilis that is also used to assess response to therapy, to detect CNS involvement, and as an aid in the diagnosis of congenital syphilis. The basis of the test is that an antibody produced by a patient with syphilis reacts with an extract of ox heart (diphosphatidyl glycerol). It therefore detects anti-cardiolipin antibodies (IgG, IgM or IgA), visualized through foaming of the test tube fluid, or "flocculation".
The RPR (Rapid Plasma Reagin) test uses the same antigen as the VDRL, but in that test it has been bound to several other molecules including a carbon particle to allow visualization of the flocculation reaction without the need of a microscope.
Many other medical conditions can produce false positive results, including some viruses (mononucleosis, hepatitis), drugs, pregnancy, rheumatic fever, rheumatoid arthritis, lupus, and leprosy.
The syphilis anti-cardiolipin antibodies are beta-2 glycoprotein independent,[2] whereas those that occur in the antiphospholipid antibody syndrome (associated to lupus for example) are beta-2 glycoprotein dependent, and this can be used to tell them apart in an ELISA assay.[3] This test is very useful as the trend of titres are correlated to disease activity (i.e. falling titres indicate successful treatment). It has a very good sensitivity for syphilis, except in late tertiary form.

Other tests

VDRL slides used in India
There are a number of treponemal-specific tests such as the Fluorescent treponemal antibody-absorption (FTA-ABS) test, Treponema pallidum hemagglutination assays (TPHA and MHA-TP)(Microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after another method tests positive for the syphilis bacteria. The MHA-TP test detects antibodies to the bacteria that cause syphilis and can be used to detect syphilis in all stages, except during the first 3 to 4 weeks. This test is not done on spinal fluid. The MHA-TP test is rarely used any more.,[4] Treponema pallidum particle agglutination assay (TP-PA), and the Toluidine red unheated serum test (TRUST) which may be used to confirm a positive VDRL result. These tests are more specific for syphilis than non-treponemal tests and, in the presence of a positive test, more likely indicate active infection. Unfortunately other treponemal infections such as yaws, bejel and pinta and possibly nonpathogenic commensal treponemes can result in a positive.
However it must be noted that all treponemal specific tests will remain positive for life once a person has been infected with syphilis, even if syphilis has been adequately treated. Therefore, these types of tests cannot be used to monitor the treatment of syphilis. automated RPR test(ART)is available for large scale tests.

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Widal test

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Test whereby bacteria causing typhoid fever are mixed with serum containing specific antibodies obtained from an infected individual. It is a presumptive serological test for enteric fever or undulant fever. In case of Salmonella infections, it is a demonstration of the presence of O-soma false-positive result. Test results need to be interpreted carefully in the light of past history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world. Typhidot is the other test used to ascertain the diagnosis of typhoid fever. As with all serological tests, the rise in antibody levels needed to perform the diagnosis takes 7–14 days, which limits it applicability in early diagnosis. Other means of diagnosing Salmonella typhi (and paratyphi) include cultures of blood, urine and faeces. These organisms produce H2S from thiosulfate and can be easily identified on differential media such as Bismuth sulfite agar.
Often 2-mercaptoethanol is added to the Widal test. This agent more easily denatures the IgM class of antibodies, so if a decrease in the titer is seen after using this agent, it means that the contribution of IgM has been removed leaving the IgG component. This differentiation of antibody classes is important; as it allows for the distinction of a recent (IgM) from an old infection (IgG).
The Widal test is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance due to the number of cross reacting infections, including malaria. If no other tests (either bacteriologic culture or more specific serology) are available, a fourfold increase in the titer (e.g., from 1:40 to 1:160) in the course of the infection, or a conversion from an IgM reaction to an IgG reaction of at least the same titer, would be consistent with a typhoid infection.

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Human gastrointestinal tract

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Jump to: navigation, search
Human gastrointestinal tract (Digestive System)
Stomach colon rectum diagram.svg
Stomach colon rectum diagram
The human gastrointestinal tract refers to the stomach and intestine,[1] and sometimes to all the structures from the mouth to the anus.[2] (The "digestive system" is a broader term that includes other structures, including the accessory organs of digestion).[3]
In an adult male human, the gastrointestinal (GI) tract is 5 metres (20 ft) long in a live subject, or up to 9 metres (30 ft) without the effect of muscle tone, and consists of the upper and lower GI tracts. The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment of the tract.
The GI tract always releases hormones to help regulate the digestion process. These hormones, including gastrin, secretin, cholecystokinin, and grehlin, are mediated through either intracrine or autocrine mechanisms, indicating that the cells releasing these hormones are conserved structures throughout evolution.[4]

Upper gastrointestinal tract

Salivary glands Parotid gland Submandibular gland Sublingual gland Pharynx Tongue Esophagus Pancreas Stomach Pancreatic duct Ileum Anus Rectum Vermiform appendix Cecum Descending colon Ascending colon Transverse colon Colon (anatomy) Bile duct Duodenum Gallbladder Liver Oral cavity
Upper and Lower human gastrointestinal tract
The upper gastrointestinal tract consists of the esophagus, stomach, and duodenum.[5] The exact demarcation between "upper" and "lower" can vary. Upon gross dissection, the duodenum may appear to be a unified organ, but it is often divided into two parts based upon function, arterial supply, or embryology.

Lower gastrointestinal tract

The Lower Gastrointestinal Tract includes most of the Small Intestine and all of the Large Intestine.[6] According to some sources, it also includes the Anus.[citation needed]
The Ligament of Treitz is sometimes used to divide the upper and lower GI tracts.[7]

Embryology

The gut is an endoderm-derived structure. At approximately the sixteenth day of human development, the embryo begins to fold ventrally (with the embryo's ventral surface becoming concave) in two directions: the sides of the embryo fold in on each other and the head and tail fold toward one another. The result is that a piece of the yolk sac, an endoderm-lined structure in contact with the ventral aspect of the embryo, begins to be pinched off to become the primitive gut. The yolk sac remains connected to the gut tube via the vitelline duct. Usually this structure regresses during development; in cases where it does not, it is known as Meckel's diverticulum.
During fetal life, the primitive gut can be divided into three segments: foregut, midgut, and hindgut. Although these terms are often used in reference to segments of the primitive gut, they are also used regularly to describe components of the definitive gut as well.
Each segment of the gut gives rise to specific gut and gut-related structures in later development. Components derived from the gut proper, including the stomach and colon, develop as swellings or dilatations of the primitive gut. In contrast, gut-related derivatives — that is, those structures that derive from the primitive gut but are not part of the gut proper, in general develop as out-pouchings of the primitive gut. The blood vessels supplying these structures remain constant throughout development.[8]
Part Part in adult Gives rise to Arterial supply
Foregut Esophagus to first 2 sections of the duodenum Esophagus, Stomach, Duodenum (1st and 2nd parts), Liver, Gallbladder, Pancreas, Superior portion of pancreas
(Note that though the Spleen is supplied by the celiac trunk, it is derived from dorsal mesentery and therefore not a foregut derivative)
celiac trunk
Midgut lower duodenum, to the first two-thirds of the transverse colon lower duodenum, jejunum, ileum, cecum, appendix, ascending colon, and first two-thirds of the transverse colon branches of the superior mesenteric artery
Hindgut last third of the transverse colon, to the upper part of the anal canal last third of the transverse colon, descending colon, rectum, and upper part of the anal canal branches of the inferior mesenteric artery

Transit time

The time taken for food or other ingested objects to transit through the gastrointestinal tract varies depending on many factors, but roughly, it takes 2.5 to 3 hours after a meal for 50% of stomach contents to empty into the intestines and total emptying of the stomach takes 4 to 5 hours. Subsequently, 50% emptying of the small intestine takes 2.5 to 3 hours. Finally, transit through the colon takes 30 to 40 hours.[9]

Pathology

There are a number of diseases and conditions affecting the gastrointestinal system, including:

Immune function

The gastrointestinal tract is also a prominent part of the immune system.[10] The surface area of the digestive tract is estimated to be the surface area of a football field. With such a large exposure, the immune system must work hard to prevent pathogens from entering into blood and lymph.[11]
The low pH (ranging from 1 to 4) of the stomach is fatal for many microorganisms that enter it. Similarly, mucus (containing IgA antibodies) neutralizes many of these microorganisms. Other factors in the GI tract help with immune function as well, including enzymes in saliva and bile. Enzymes such as Cyp3A4, along with the antiporter activities, also are instrumental in the intestine's role of detoxification of antigens and xenobiotics, such as drugs, involved in first pass metabolism.
Health-enhancing intestinal bacteria serve to prevent the overgrowth of potentially harmful bacteria in the gut. These two types of bacteria compete for space and "food," as there are limited resources within the intestinal tract. A ratio of 80-85% beneficial to 15-20% potentially harmful bacteria generally is considered normal within the intestines. Microorganisms also are kept at bay by an extensive immune system comprising the gut-associated lymphoid tissue (GALT).

Histology

General structure of the gut wall
The gastrointestinal tract has a form of general histology with some differences that reflect the specialization in functional anatomy.[12] The GI tract can be divided into four concentric layers:

Mucosa

The mucosa is the innermost layer of the gastrointestinal tract. that is surrounding the lumen, or open space within the tube. This layer comes in direct contact with digested food (chyme),
The mucosa is made up of three layers:
  • Epithelium - innermost layer. Responsible for most digestive, absorptive and secretory processes.
  • Lamina propria - a layer of connective tissue. Unusually cellular compared to most connective tissue
  • Muscularis mucosae - a thin layer of smooth muscle. Function is still under debate
The mucosae are highly specialized in each organ of the gastrointestinal tract to deal with the different conditions. The most variation is seen in the epithelium.
In the oesophagus, the epithelium is stratified, squamous and non-keratinising, for protective purposes.
In the stomach it is simple columnar, and is organised into gastric pits and glands to deal with secretion. The gastro-oesophageal junction is extremely abrupt.
The small intestine epithelium (particularly the ileum) is specialised for absorption; it is organised into plicae circulares and villi, and the enterocytes have microvilli. This creates a brush border which greatly increases the surface area for absoption. The epithelium is simple columnar with microvilli. In the ileum there are occasionally Peyer's patches in the lamina propria.
The colon has simple columnar epithelium with no villi. There are goblet cells.
The appendix has a mucosa resembling the colon but is heavily infiltrated with lymphocytes.
The ano-rectal junction (at the pectinate line) is again very abrupt; there is a transition from simple columnar to stratified squamous non-keratinising epithelium (as in the oesophagus) for protective purposes.

Submucosa

The submucosa consists of a dense irregular layer of connective tissue with large blood vessels, lymphatics, and nerves branching into the mucosa and muscularis externa. It contains Meissner's plexus, an enteric nervous plexus, situated on the inner surface of the muscularis externa.

Muscularis externa

The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer. The circular muscle layer prevents food from traveling backward and the longitudinal layer shortens the tract. Actually the layers are not truly longitudinal or circular, rather the layers of muscle are helical with different pitches. The inner circular is helical with a steep pitch and the outer longitudinal is helical with a much shallower pitch.
The coordinated contractions of these layers is called peristalsis and propels the food, through the tract. Food in the GI tract is called a bolus (ball of food) from the mouth down to the stomach. After the stomach the food is partially digested and semi-liquid, and is referred to as chyme. In the large intestine the remaining semi-solid substance is referred to as faeces.
Between the two muscle layers are the myenteric or Auerbach's plexus. This controls peristalsis. Activity is initiated by the pacemaker cells (interstitial cells of Cajal). The gut has intrinsic peristaltic activity (basal electrical rhythm) due to its self-contained enteric nervous system. The rate can of course be modulated by the rest of the autonomic nervous system.
The thickness of muscularis externa varies in each part of the tract. In the colon, for example, the muscularis externa is much thicker because the faeces are large and heavy, and require more force to push along. The outer longitudinal layer of the colon thins out into 3 discontinuous longitudinal bands, known as tiniae coli (bands of the colon). This is one of the 3 features helping to distinguish between the large and small intestine.
Occasionally in the large intestine (2-3 times a day) there will be mass contraction of certain segments, moving a lot of faeces along. This is generally when one gets the urge to defacate.
The pylorus of the stomach has a thickened portion of the inner circular layer: the pyloric sphincter. Alone among the GI tract, the stomach has a third layer of muscularis externa. This is the inner oblique layer, and helps churn the chyme in the stomach.

Adventitia/serosa

The outermost layer of the GI tract consists of several layers of connective tissue.
Intraperitoneal parts of the GI tract are covered with serosa. These include most of the the stomach, first part of the duodenum, all of the small intestine, caecum and appendix, transverse colon, sigmoid colon and rectum. In these sections of the gut there is clear boundary between the gut and the surrounding tissue. These parts of the tract have a mesentery.
Retroperitoneal parts are covered with adventitia. They blend in to the surrounding tissue and are fixed in position. For example, the retroperitoneal section of the duodenum usually passes through the transpyloric plane. These include the oesophagus, pylorus of the stomach, distal duodenum, ascending colon, descending colon and anal canal. In addition, the oral cavity has adventitia.

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