Radiation


Radiation with sufficiently high energy can ionize atoms; that is to say it can knock electrons off of atoms and create ions. This occurs when an electron is stripped (or "knocked out") from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, it can result in an increased chance of cancer.

Thus "ionizing radiation" is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell is made of trillions of atoms, only a small fraction of those will be ionized at low radiation powers.

The probability of ionizing radiation causing cancer is dependent upon the absorbed dose of the radiation, and is a function of the damaging tendency of the type of radiation (equivalent dose) and the sensitivity of the irradiated organism or tissues (effective dose).


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Roughly speaking, photons and particles with energies above about 10 electron volts (eV) are ionizing. Alpha particles, beta particles, cosmic rays, gamma rays, and X-ray radiation, all carry enough energy to ionize atoms. In addition, free neutrons are also ionizing since their interactions with matter are inevitably more energetic than this threshold.

Ionizing radiation originates from radioactive materials, X-ray tubes, particle accelerators, and is naturally present in the environment. It is invisible and not directly detectable by human senses; as a result, instruments such as Geiger counters are usually required to detect its presence. In some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence.

Ionizing radiation has many practical uses in medicine, research and construction, but presents a health hazard if used improperly. Exposure to radiation causes damage to living tissue; high doses result in skin burns, radiation sickness and death, while low but persistent doses result in cancer tumors and genetic damage.

Electromagnetic radiation (EMR) is represented as self-propagating waves. EMR has electric and magnetic field components that oscillate in phase perpendicular to each other and also to the direction of energy propagation. EMR is classified into types according to the frequency range of the waves, these types include (in order of increasing frequency): radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

Of these, radio waves have the longest wavelengths (lowest energy) and gamma rays have the shortest and hence the highest energy. A small window of frequencies, called the visible spectrum or light, is sensed by the eyes of various organisms.

Ionizing electromagnetic radiation is that for which the photons making up the radiation have energies larger than about 10 electron volts. The ability of an electromagnetic wave (photons) to ionize an atom or molecule thus depends on its frequency, which determines the energy of a photon of the radiation.

An energy of 10 eV is about 1.6×10 joules, which is a typical binding energy of an outer electron to an atom or organic molecule. This corresponds with a frequency of 2.4×1015 Hz, and a wavelength of 125 nm (this is in far ultraviolet) or less.(wikipedia.org)

Optical V


Fiber optics, though used extensively in the modern world, is a fairly simple, and relatively old, technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later.

Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870: "When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be totally reflected at the surface....

The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27', for flint glass it is 38°41', while for diamond it is 23°42'." Unpigmented human hairs have also been shown to act as an optical fiber.

Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for internal medical examinations by Heinrich Lamm in the following decade. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade.


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Development then focused on fiber bundles for image transmission. Harold Hopkins and Narinder Singh Kapany at Imperial College in London achieved low-loss light transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954 The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C.

Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material.
A variety of other image transmission applications soon followed.


In 1880 Alexander Graham Bell and Sumner Tainter invented the 'Photophone' at the Volta Laboratory in Washington, D.C., to transmit voice signals over an optical beam. It was an advanced form of telecommunications, but subject to atmospheric interferences and impractical until the secure transport of light that would be offered by fiber-optical systems. In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities.

Jun-ichi Nishizawa, a Japanese scientist at Tohoku University, also proposed the use of optical fibers for communications in 1963, as stated in his book published in 2004 in India. Nishizawa invented other technologies that contributed to the development of optical fiber communications, such as the graded-index optical fiber as a channel for transmitting light from semiconductor lasers.

The first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, which was followed by the first patent application for this technology in 1966. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer (dB/km), making fibers a practical communication medium.

 They proposed that the attenuation in fibers available at the time was caused by impurities that could be removed, rather than by fundamental physical effects such as scattering. They correctly and systematically theorized the light-loss properties for optical fiber, and pointed out the right material to use for such fibers — silica glass with high purity. This discovery earned Kao the Nobel Prize in Physics in 2009.

NASA used fiber optics in the television cameras that were sent to the moon. At the time, the use in the cameras was classified confidential, and only those with the right security clearance or those accompanied by someone with the right security clearance were permitted to handle the cameras.(wikipedia.org)

Binatang


Harimau yang juga dipanggil harimau belang merupakan spesies kucing terbesar di kalangan empat jenis -kucing- besar dalam genus Panthera, dan anggota famili Felidae

Harimau yang asal muasal dari Asia timur dan selatan ini ialah sejenis hewan pemangsa. Subspesies harimau yang lebih besar berukuran panjang 3.3 meter (11 kaki) dan memiliki bobot sekitar 300 kilogram atau 660 paun.

Selain kebesaran dan kegagahannya, hal terpenting lain yang dimiliki harimau ialah corak kulit atau bulu belang menegak berwarna gelap yang melapisi bulunya yang berwarna keputihan atau merah kejinggaan.


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Harimau juga mempunyai ciri amat mudah beradaptasi diri dengan lingkungan baru, terdapat dari kawasan tiga Siberia, ke padang rumput terbuka, ke paya bakau tropika, antara lainnya.

Harimau ialah hewan yang cenderung gemar bersendiri dan berkelakuan menandakan wilayah seperti pada jenis kucing pada umumnya, dan sering memerlukan kawasan habitat yang amat luas untuk menampung keperluan memburu mangsanya.

Sering menyebabkan terjadinya konflik antara harimau dan manusia. Tiga dari pada sembilan subspesies harimau moden sudah di anggap punah dan enam yang selebihnya masuk dalam kategori di ambang kepunahan.


Harimau yang dulu pernah menduduki kawasan-kawasan seluas Mesopotamia dan Caucasus hingga Asia Selatan dan Timur, kini semakin berkurangan kawasan habitatnya akibat dari ulah kita sebagai manusia. Walaupun semua spesies yang masih ada diberi perlindungan undang-undang, namun tetap saja pemburuan, kemusnahan habitat tetap belum bisa sepenuhnya di atasi dengan garang.

Harimau tetap menjadi salah satu jenis megafauna berkarisma yang terlahir di dunia. Harimau juga banyak memainkan peranan penting dalam beberapa mitos dan budaya rakyat, di samping dalam hal ini masih mendapat tempat dalam bidang perfileman dan kesusasteraan moden.(wikipedia.org)

Produksi


Dahulu kala jembatan pertama yang dibuat dengan menggunakan bahan kayu untuk menyeberangi sungai. Ada juga orang yang menggunakan dua buah utas tali atau rotan, yang diikat pada bebatuan di tepi sungai.

pada zaman dahulu orang-orang Roma juga mempunyai pengetahuan, yang mengurangkan perbedaan kekuatan batu2 yang berbeda. dan akhirnya jembatan bata dan mortar dibuat pada kekaisaran Romawi, karena sesudah zaman tersebut, teknologi pengetahuan telah hilang.

dan pada Zaman Pertengahan, tiang-tiang jembatan batu biasanya lebih besar sehingga menyebabkan kesulitan kepada kapal-kapal yang lalu-lalang di sungai tersebut.


www.mbaeh.biz

Pada abad ke-18, dan akhirnya mulai banyak pembaruan dalam pembuatan jembatan kayu salah satunya oleh Hans Ulrich, serta Johannes Grubenmann dan lain-lain. Dengan beradanya Revolusi Industri pada abad ke-19.

sistem rangka (truss system) yang pada dasarnya menggunakan besi untuk memajukan untuk pembuatan jembatan yang lebih besar kuat serta stabil atau tahan banting, tetapi besi tidak mempunyai kekuatan ketegangan (tensile strength) yang cukup untuk beban yang besar.


sedangkan Apabila mempunyai ketegangan yang tinggi, jembatan yang cukup besar akan dibuat, kebanyakannya menggunakan idea Gustave Eiffel, yang saat pertama kali dipertunjukkan di Menara Eiffel di Paris, Perancis.

Yang tentunya sesuai digunakan untuk pembuatan jembatan yang panjang karena ia mempunyai kekuatan-kepada-berat yang tinggi, tetapi konkrit pula mempunyai kos penjagaan yang lebih murah. Jadi, selalunya "konkrit diperkuat" (reinforced concrete) digunakan - kekuatan ketegangan konkrit yang lemah diisi oleh kabel tembaga yang ditanam di dalam konkrit itu.(wikipedia.org)

Teknologi


Segmen tablet memang selalu identik dengan iPad milik Apple. tapi hal tersebut sepertinya akan segera berubah dalam beberapa waktu yang akan datang. Hal itu nantinya pun bisa terlihat dengan beberapa kabar yang hangat akhir-akhir ini.

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Menurut JD Power dalam sebuah survei nya, terungkap bahwa tablet milik Samsung saat ini memiliki tingkat kepuasan yang lebih baik dibanding iPad Apple.

Survei tersebut didasarkan atas lima faktor yang maksimum akan memperoleh poin sekitar 1000. Lima faktor tersebut adalah bobot, performa, kemudahan pemakaian, desain, fitur dan yang terakhir adalah harga.
  1. Samsung: 835
  2. Apple: 833
  3. Amazon: 826
  4. ASUS: 821
  5. Acer: 781
Dan dalam posisi lima besar tersebut nampak jelas terlihat bahwa Samsung memang memiliki keunggulan yang sangat sangat tipis dengan rival nya yaitu Apple.

Dan keunggulan tersebut tampak jelas pada faktor harga, di mana Samsung menyediakan tablet dengan variasi harga yang lebih banyak dibanding Apple.

dan bukan hanya itu, tingkat penjualan iPad kini juga mengalami tingkat penurunan dengan prosentase di bawah 30 persen.


Angka tersebut pun bisa disebut yang paling rendah dalam sejarah penjualan iPad Apple. tapi hal tersebut bisa saja berubah seiring dengan mulainya penjualan iPad Air.(beritateknologi.com)

Kesehatan


Selain hati, paru-paru merupakan salah satu organ yang cukup vital di dalam tubuh manusia. Paru-paru mempunyai beberapa fungsi utama salah satunya sebagai tempat pergantian udara dalam tubuh.

Seperti dinukil dari mindbodygreen.com, kesehatan kulit dan kekebalan tubuh manusia sangat bergantung pada kesehatan paru-paru kita. Jaringan paru-paru sangat halus serta rentan terhadap iritasi terutama pada udara yang cukup dingin.


http://www.tokosarangsemut.com

Berikut adalah beberapa tips mudah untuk menjaga kesehatan paru-paru Anda.

Mengurangi paparan zat klorin

Zat klorin bukan hanya datang dari makanan yang anda konsumsi, tapi juga bisa datang dari udara yang kita hirup. Zat klorin lebih banyak terdapat di dalam air keran yang kita gunakan sehari-hari. untuk mengurangi dampak dari klorin, kita juga dapat memasang filter di keran air Anda.
Hindari makanan pencetus lendir

Apabila cukup banyak ditemukan lendir dalam paru-paru, maka bisa dipastikan kapasitas udara yang disimpan dalam paru-paru kita akan lebih sedikit. Lendir dapat terbentuk karena makanan. Hindarilah mengonsumsi gula dan bahan kimia lainya yang terkandung dalam makanan kita.(wikipedia.org)