Selasa, 27 September 2011

COAXIAL CABLE


Coaxial cable, or coax, is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880.[1]

Coaxial cable is used as a transmission line for radio frequency signals. Its applications include feedlines connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable televisionsignals. One advantage of coax over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors. This allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other types of transmission lines. Coaxial cable also provides protection of the signal from external electromagnetic interference.

Coaxial cable differs from other shielded cable used for carrying lower frequency signals, such as audio signals, in that the dimensions of the cable are controlled to give a precise, constant conductor spacing, which is needed for it to function efficiently as a radio frequency transmission line.

TWISTED PAIR CABLE


In balanced pair operation, the two wires carry equal and opposite signals and the destination detects the difference between the two. This is known asdifferential mode transmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields and tend to couple to both wires equally. The noise thus produces a common-mode signal which is cancelled at the receiver when the difference signal is taken. This method starts to fail when the noise source is close to the signal wires; the closer wire will couple with the noise more strongly and the common-mode rejection of the receiver will fail to eliminate it. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles. One pair can induce crosstalk in another and it is additive along the length of the cable. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise-source is exchanged. Providing the interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode. Differential signaling also reduces electromagnetic radiation from the cable, along with the associated attenuation allowing for greater distance between exchanges.

The twist rate (also called pitch of the twist, usually defined in twists per meter) makes up part of the specification for a given type of cable. Where nearby pairs have equal twist rates, the same conductors of the different pairs may repeatedly lie next to each other, partially undoing the benefits of differential mode. For this reason it is commonly specified that, at least for cables containing small numbers of pairs, the twist rates must differ.[1]

In contrast to FTP (foiled twisted pair) and STP (shielded twisted pair) cabling, UTP (unshielded twisted pair) cable is not surrounded by any shielding. It is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due to the high flexibility of the cables.

[edit]

Jumaat, 24 Jun 2011

Tenaga Pengajar

BAHASA MELAYU-PUAN ZALEHA ABDUL SAMAD
BAHASA INGGERIS-MADAM FATHIAH RASHID
MATEMATIK-ENCIK HASSAN PUTEH
SAINS-PUAN ZALEHA SAIIN
AGAMA ISLAM-PUAN HAJAH NOREHA JOHDI
SEJARAH-PUAN SARIMAH SHUIB
PRINSIP PERAKAUNAN-PUAN ZARINA AHMAD
I.C.T-ENCIK BASORI ABDUL RAHMAN&PUAN NURUL AMALINA
MATEMATIK TAMBAHAN-ENCIK CHE SALIM ABU BAKAR

JADUAL WAKTU KELAS

ISNIN
08:15-09:25 Matematik Tambahan
09:25-1035 Bahasa Melayu
10:35-10:55 Rehat
10:55-11:30 Sains
11:30-12:05 Matematik
12:05-13:15 Prinsip Perakaunan

SELASA
07:35-08:10 Matematik
08:10-08:45 PJPK
08:45-09:20 PSK
09:20-10:30 Prinsip Perakaunan
10:30-10:50 Rehat
10:50-11:25 Pendidikan Agama Islam
11:25-12:35 Sains
12:35-13:10 Matematik Tambahan
13:10-13:45 Bahasa Inggeris

RABU
07:35-08:10 PSK
08:10-09:20 ICT
09:20-10:30 Bahasa Inggeris
10:30-10:50 Rehat
10:50-11:25 Matematik Tambahan
11:25-12:35 Sains
12:35-13:45 Matematik

KHAMIS
07:35-08:10 Matematik Tambahan
08:10-09:20 ICT
09:20-10:30 Bahasa Melayu
10:30-10:50 Rehat
10:50-12:00 Sejarah
12:00-13:10 Pendidikan Agama Islam
13:10-13:45 Bahasa Inggeris

JUMAAT
08:00-08:35 Sejarah
08:35-09:10 Bahasa Inggeris
09:10-09:45 PJPK
09:45-10:20 Matematik
10:20-10:40 Rehat
10:40-11:15 Pendidikan Agama Islam
11:15-12:25 Bahasa Melayu

Aktiviti Kelas

22 Jun 2011 : Pc Assembly (ICT)

Aktiviti Kelas

20 Jun 2011 : Kuiz Prinsip Akaun

Aktiviti Kelas

22 Januari 2011: Mengadakan Gotong-royong menghias kelas.

Jadual Harian

Selasa, 21 Jun 2011

5 USM KELASKU ~

-UMMU SUHAINA ABDUL RAHMAN
-MIMIE ROZMIZA ROZMAN
-EVA NATASHA AHMAD
-CHAN KAH MUN
-TAN SU YING
-ENNI EFAFIQA
-HIDAYATUL UMAIRAH
-NUR HIDAYAH
-FARAH NINI
-NURUL HAZIRAH
-CHUAH CHE YIN
-LIM KAI LOON
-NG JUN HAO
-SHU PHOOI SEE
-YEAP SHI HUI
-SITI SHUHADA ANUM
-YOGARAJAN
-YASOTARAN
-SATISWARAN
-WAN NURUL ASYIKIN
-NURUL KHATIJAH
-REMECCA
-UHUNESHWARY
-LEE HWANG GAO
-TEH WEI JUN
-AZMAN
-NAZRUN NAIM
-FADHULAH
-ISZWAN
-IZZUDDIN
-HARITH AQIF

Khamis, 16 Jun 2011

Hackers Target Malaysian Government Sites


A number of Malaysian government Web sites fell prey to cyber attacks Wednesday night in a coordinated effort possibly organized by members of the clandestine Web group, Anonymous.

Ninety-one Web sites were attacked starting at 11:30pm local time, the Malaysian Communications and Multimedia Commission told Bloomberg. Seventy-six have since come back online.

Earlier this week, an image from Anonymous circulated, calling on supporters to attack malaysia.gov.my on June 15 at 7:30pm GMT.

In a YouTube video (below) posted on June 14, Anonymous criticized Malaysian government officials for their censorship of the Web.

"We have seen the censorship taken by the Malaysian government, blocking sites like The Pirate Bay, and WikiLeaks," according to a voice in the video, which was set to music from the movie Inception. "Malaysia is one of the world's strictest governments, even blocking out movies, and television shows. These acts of censorship are inexcusable. You are taking away a basic human right. The Internet is here for freedom, without fear of government interference."

The video went on to warn Malaysian officials that "this is a sign, a warning, and an opportunity to listen to ideas above your own."

"Now we will wash your corruption away so be prepared. Take this as a favour," the group concluded.

Malaysia, however, has not been mentioned on the AnonOps Twitter feed or blog. Most recently, those sites have named Federal Reserve chairman Ben Bernanke as the next Anonymous target. Anonymous, however, is a rather splintered group. If you say you are a member of Anonymous, you are a member of Anonymous, making the group difficult to track. Bloomberg reports that many of the Malaysia attacks came from unidentified local hackers, who set up a blog to share updates.

The fractured nature of Anonymous, however, hasn't stopped some officials from crackdowns. Members of the group were arrested in Spain and Turkey this week over distributed denial of service (DDoS) attacks similar to the ones that affected the Malaysia sites.

Selasa, 1 Mac 2011

Ruby (programming language)

Ruby is a dynamic, reflective, general purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto. It was influenced primarily by Perl, Smalltalk, Eiffel, and Lisp.

Ruby supports multiple programming paradigms, including functional, object oriented, imperative and reflective. It also has a dynamic type system and automatic memory management; it is therefore similar in varying respects to Python, Perl, Lisp, Dylan, Pike, and CLU.

The standard 1.8.7 implementation is written in C, as a single-pass interpreted language. There is currently no specification of the Ruby language, so the original implementation is considered to be the de facto reference. As of 2010, there are a number of complete or upcoming alternative implementations of the Ruby language, including YARV, JRuby, Rubinius, IronRuby, MacRuby, and HotRuby. Each takes a different approach, with IronRuby, JRuby and MacRuby providing just-in-time compilation and MacRuby also providing ahead-of-time compilation. The official 1.9 branch uses YARV, as will 2.0 (development), and will eventually supersede the slower Ruby MRI.

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode (class file) that can run on any Java Virtual Machine (JVM) regardless of computer architecture. Java is a general-purpose, concurrent, class-based, object-oriented language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere". Java is currently one of the most popular programming languages in use, and is widely used from application software to web applications.[9][10]

The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun relicensed most of its Java technologies under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java, GNU Classpath, and Dalvik.

Selasa, 18 Januari 2011

Programming Language Generations


- In the computer industry, these abbreviations are widely used to represent major steps or "generations" in the evolution of programming languages.
1GL or first-generation language was (and still is) machine language or the level of instructions and data that the processor is actually given to work on (which in conventional computers is a string of 0s and 1s).
2GL or second-generation language is assembler (sometimes called "assembly") language. A typical 2GL instruction looks like this: ADD 12,8
An assembler converts the assembler language statements into machine language.
3GL or third-generation language is a "high-level" programming language, such as PL/I, C, or Java. Java language statements look like this: public boolean handleEvent (Event evt) {
switch (evt.id) {
case Event.ACTION_EVENT: {
if ("Try me" .equald(evt.arg)) {
A compiler converts the statements of a specific high-level programming language into machine language. (In the case of Java, the output is called bytecode, which is converted into appropriate machine language by a Java virtual machine that runs as part of an operating system platform.) A 3GL language requires a considerable amount of programming knowledge.
4GL or fourth-generation language is designed to be closer to natural language than a 3GL language. Languages for accessing databases are often described as 4GLs. A 4GL language statement might look like this: EXTRACT ALL CUSTOMERS WHERE "PREVIOUS PURCHASES" TOTAL MORE THAN $1000
5GL or fifth-generation language is programming that uses a visual or graphical development interface to create source language that is usually compiled with a 3GL or 4GL language compiler. Microsoft, Borland, IBM, and other companies make 5GL visual programming products for developing applications in Java, for example. Visual programming allows you to easily envision object-oriented programming class hierarchies and drag icons to assemble program components.

Programming Language


A programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication.
The earliest programming languages predate the invention of the computer, and were used to direct the behavior of machines such as Jacquard looms and player pianos. Thousands of different programming languages have been created, mainly in the computer field, with many more being created every year. Most programming languages describe computation in an imperative style, i.e., as a sequence of commands, although some languages, such as those that support functional programming or logic programming, use alternative forms of description.
A programming language is usually split into the two components of syntax (form) and semantics (meaning) and many programming languages have some kind of written specification of their syntax and/or semantics. Some languages are defined by a specification document, for example, the C programming language is specified by an ISO Standard, while other languages, such as Perl, have a dominant implementation that is used as a reference.

Isnin, 8 November 2010

Perang Siber


KETIKA Amerika Syarikat meraikan ulang tahun kemerdekaannya pada 4 Julai lalu,satu siri serangan siber berupa serangan denial-of-service (DDoS) telah dilancarkan ke atas rangkaian Internet di Amerika Syarikat dan Korea Selatan .
Ia menyaksikan kira-kira 25 laman web agensi kerajaan dan syarikat termasuk Rumah Putih,Jabatan Perbendaharaan,Jabatan Pengangkutan,Suruhanjaya Perdagangan Persekutuan,Jabatan Pertahanan,Agensi Keselamatan Nasional,Jabatan Keselamatan Dalam Negeri,Bursa Saham Nasdaq dan New York serta akhbar The Washington Post mengalami gangguan.
Di Korea Selatan,siri serangan tersebut berlarutan sehingga 8 Julai yang menyaksikan 11 organisasi termasuk Pejabat Presiden yang dikenali sebagai Blue House dan Kementerian Pertahanan serta salah sebuah bank terbesar di Korea Selatan,akhbar utama dan agensi perisikannya menjadi sasaran serangan yang mengakibatkan laman web organisasi berkenaan lumpuh atau sukar diakses.
Menurut laporan media,serangan siber ke atas Amerika Syarikat dan Korea Selatan itu didakwa dilakukan oleh Korea Utara.
Jika disoroti insiden serangan siber yang serupa seperti yang dialami oleh Amerika Syarikat dan Korea Selatan baru-baru ini,ia bukanlah kejadian pertama yang berlaku. Estonia (2007),Georgia (2008) dan Kyrgyzstan (Januari 2009) pernah mengalami serangan siber dan yang dituduh menjadi dalang serangan ke atas ketiga-tiga negara itu ialah Rusia.
Persoalannya,apakah benar Korea Utara dan Rusia bertanggungjawab melancarkan perang siber atau ia sekadar hipotesis pihak media dan penganalisis?
Dalam insiden serangan siber ke atas Estonia,Georgia,Kyrgyzstan dan baru-baru ini ke atas Amerika Syarikat dan Korea Selatan,tiada bukti kukuh pembabitan Rusia dan Korea Utara dalam serangan tersebut.
Jika analisis dan hipotesis penganalisis diambil kira,China,Rusia dan Korea Utara adalah antara negara yang mempunyai kekuatan tentera yang terkuat di alam siber.
Rusia dan China adalah dua buah negara yang sering memperagakan keupayaan ketenteraan mereka di alam siber berdasarkan beberapa insiden serangan siber yang didakwa oleh penganalisis-penganalisis keselamatan siber dilancarkan oleh kedua-dua negara berkenaan.
Rusia didakwa memiliki militia siber yang mengawal botnet terbesar di dunia iaitu antara 150 hingga 180 juta nod.
Kebiasaannya,serangan siber berupa DDoS boleh dilancarkan menerusi nod tersebut walaupun nod tersebut tidak berada di negara yang melancarkan serangan. Namun sehingga kini,belum ada bukti kukuh untuk mengaitkan serangan ke atas Estonia,Georgia dan Kyrgyzstan itu dilancarkan oleh militia siber Rusia.
kekuatan ketenteraan
China bukan sahaja merupakan negara yang mempunyai jumlah tentera yang teramai yakni 2.3 juta orang malah di alam siber kekuatan ketenteraan China sering mendapat perhatian kuasa besar dunia seperti Amerika Syarikat dan Britain.
Dalam tahun 2007,ketika serangan siber ke atas Australia dan New Zealand tercetus,China didakwa menjadi dalang serangan tersebut.
Malah,dilaporkan China mempunyai bala tentera siber yang terdiri daripada Tentera Pembebasan Rakyat (PLA) yang sering menceroboh rangkaian komputer di Amerika Syarikat,Kanada,Jerman dan Jepun bagi mengumpul maklumat dan mencuri data penting negara-negara berkenaan.
Namun sehingga ke hari ini,tiada bukti kukuh atas dakwaan tersebut.
Korea Utara yang menyertai China dan Rusia dalam senarai negara yang memiliki tentera siber yang besar didakwa telah bertahun-tahun memiliki sepasukan tentera yang dianggotai oleh kira-kira 100 penggodam yang kebanyakannya adalah graduan akademi tentera di Pyongyang yang bertanggungjawab mengumpul maklumat dan mengganggu jaringan komputer di Korea Selatan dan Amerika Syarikat.
Malah sumber perisikan Korea Selatan pernah mendedahkan bahawa Korea Utara mempunyai 'Unit 121' iaitu satu organisasi ketenteraan yang dianggotai oleh 500-1000 penggodam mahir yang pernah menggodam jabatan pertahanan Korea Selatan dan Amerika Syarikat.
Seperti dalam kes Rusia,segala dakwaan ke atas Korea Utara hanyalah hipotesis penganalisis.
Malah menurut seorang penyelidik botnet,berdasarkan analisis yang dibuat ke atas kod perisian berbahaya (malware) yang digunakan dalam serangan ke atas Amerika Syarikat dan Korea Selatan,tiada penunjuk yang membuktikan serangan tersebut dilakukan atau didalangi oleh Korea Utara.
Jadi,apakah benar Rusia,China dan Korea Utara mampu melancarkan perang siber ke atas musuh mereka seperti yang dilaporkan oleh media barat atau ia sebahagian daripada propaganda politik Amerika Syarikat dalam meneruskan hegemoninya?
Dari satu sudut,memang tidak mustahil negara seperti Rusia,China dan Korea Utara mampu melancarkan perang siber ke atas mana-mana negara yang dimusuhi mereka.
Malah Amerika Syarikat juga mampu melakukannya kerana adalah mustahil sebuah negara maju seperti Amerika Syarikat yang memiliki teknologi dan pakar dalam teknologi maklumat tidak memiliki tentera sibernya sendiri.
Namun ada sesetengah penganalisis insiden serangan siber berpendapat,ada kemungkinan kerajaan atau tentera Rusia,China dan Korea Utara tidak terbabit langsung dalam serangan siber tersebut sebaliknya ia dilakukan oleh penggodam yang mahu menguji kemahiran mereka atau yang bersimpati dan pro negara-negara berkenaan.
Dalam kes insiden di Estonia,Georgia,Kyrgyzstan,Amerika Syarikat dan Korea Selatan,jelas ketegangan geopolitik baik di dalam negara berkenaan mahupun di peringkat antarabangsa dikatakan menjadi punca serangan.
Oleh yang demikian adalah tidak mustahil penggodam yang simpati atau pro pada pihak yang ditekan melancarkan serangan siber terhadap pihak yang menekan atas dasar simpati atau protes.
Ini terbukti dalam insiden serangan siber antara Israel-Palestin yang tercetus pada penghujung 2008 dan awal 2009 di mana isu serangan Israel ke atas Palestin ketika itu mengundang rasa simpati penggodam yang akhirnya menyaksikan kira-kira 12,862 laman web dan 72 pelayan Israel berjaya digodam.
Di Iran,ketika pilihan raya presiden pada pertengahan Jun tahun ini,12 laman web prokerajaan telah menjadi mangsa serangan siber oleh penyokong parti pembangkang,antaranya laman blog rasmi Mahmoud Ahmadinejad,Pejabat Pemerintah Agung Ayatollah Ali Khamenei,Kementerian Dalam Negeri,Polis Kebangsaan,Kementerian Keadilan dan Iranian Press TV.
Insiden serangan siber tersebut berlaku berikutan ketidakpuasan hati penyokong parti pembangkang dengan pemilihan semula Mahmoud Ahmadinejad sebagai presiden.
Penyokong pembangkang menggunakan Twitter sebagai alat komunikasi dan penyebaran maklumat mengenai kaedah untuk menyerang laman web prokerajaan.
Walaupun perang siber masih merupakan hipotesis para penganalisis,insiden serangan siber bukanlah sesuatu yang asing terutama ketika era masa kini yang menyaksikan kebergantungan tinggi manusia terhadap komputer dan Internet.
mengakses komputer
Bagi segelintir daripada kita,kebergantungan terhadap komputer (termasuk telefon bimbit) pada hari ini telah mencapai satu tahap di mana jika tidak mengakses komputer sama ada dengan atau tanpa Internet,kita akan merasa gelisah sepanjang hari.
Daripada urusan pejabat sehingga urusan peribadi dan untuk bersosial,komputer atau telefon bimbit menjadi satu alat yang amat penting bagi mengerjakan segala urusan.
Sesetengah pakar di negara maju berpendapat,kebergantungan yang amat tinggi terhadap komputer (Internet) untuk melakukan apa saja urusan penting boleh mencetuskan cybergeddon yakni situasi di mana pengguna mengalami kesulitan yang boleh mengancam keselamatan apabila komputer atau jaringan Internet mengalami serangan siber.
Serangan siber bukan sahaja boleh mendatangkan kerugian yang besar kepada pengguna Internet malah jika dilancarkan pada skala besar boleh melumpuhkan prasarana kritikal maklumat negara seperti jabatan kerajaan,perbankan,kewangan dan pengangkutan.
Amerika Syarikat sendiri telah mengklasifikasikan serangan siber sebagai ancaman terbesar mereka selepas perang nuklear dan senjata pemusnahan besar-besaran.
Oleh yang demikian,persoalan mengenai sejauh mana serangan siber itu boleh dianggap sebagai satu bentuk perang yang dilancarkan oleh sesebuah negara sebenarnya bergantung pada persepsi penganalisis atau pihak media yang melaporkannya.
Sama ada perang siber akan menjadi satu realiti suatu hari nanti atau kekal sekadar ilusi yang dicipta oleh kuasa besar seperti Amerika Syarikat dalam mengimbangi kebangkitan negara seperti China dan Korea Utara di pentas politik antarabangsa,yang penting insiden serangan siber tidak mustahil akan menjadi senjata perang pada masa akan datang.
Malaysia sebagai sebuah negara yang semakin bergantung pada teknologi maklumat juga harus bersiap siaga untuk mendepani serangan siber.
Redy Jeffry Mohamad Ramli dan Nadia Salwa Mohamad ialah Penyelidik Media Siber di Bahagian Keselamatan Siber dan Polisi,CyberSecurity Malaysia. Kenyataan dan pandangan yang terdapat di dalam artikel ini adalah pandangan peribadi penulis.

Selasa, 2 November 2010

KARNIVAL iCT











UBUNTU



Ubuntu (pronounced /uːˈbuːntuː/[4][5] or /uːˈbʌnˌtuː/[citation needed]) is a computeroperating system originally based on the Debian GNU/Linux distribution and distributed as free and open source software with additional proprietary software available.
It is named after the Southern African philosophy of Ubuntu ("humanity towards others").[6] Ubuntu is designed primarily for desktop usage, though netbook andserver editions exist as well.[7] Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50 percent,[8][9] and upward trending usage as a web server.[10]
Ubuntu is composed of many software packages, of which the vast majority are distributed under a free software license (also known as open source). The main license used is the GNU General Public License (GNU GPL) which, along with theGNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. Ubuntu is sponsored by the UK-based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. Canonical creates revenue by sellingtechnical support and services tied to Ubuntu.
Canonical endorses and provides support for three additional Ubuntu-derived operating systems: Kubuntu, Edubuntu, also known as Ubuntu Education Edition, and Ubuntu Server Edition. There are several other derivative operating systems including local language and hardware-specific versions.[11]
Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. LTS (Long Term Support) versions, which are released every two years,[12] are supported for three years on the desktop and five years for servers.[13] The latest version of Ubuntu, 10.10 (Maverick Meerkat), was released on October 10, 2010.

Ahad, 27 Jun 2010

Virus H1N1


Influenza A (H1N1) virus is a subtype of influenza A virus and was the most common cause of human influenza (flu) in 2009. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza. H1N1 strains caused a few percent of all human flu infections in 2004–2005.[1] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).
In June 2009, the World Health Organization declared the new strain of swine-origin H1N1 as a pandemic. This strain is often called swine flu by the public media. This novel virus spread worldwide and had caused about 17,000 deaths by the start of 2010.