Meteoritul de pe Marte isi dezvaluie varsta (Mars meteorite reveals its age)

Folosind un instrument ce poate debloca secretelr sistemului solar, s-a descoperit o noua tehnica ce determina precis varsta meteoritilor., raporteaza oamenii de stiinta in revista Nature.

Oamenii de stiinta nu se inteleg i privinta estimarii varstelor meteoritilor pentru ca este greu sa distingi perioada in care rocile s-au format si perioada in care ele au fost arse dintr-un impact si au zburat prin spatiu spre Pamant.

Geologul de la UCLA Axel Schmitt si coleii sai au inceput prin examinarea structurii cristalelor minerale ale meteoritului, care variaza, in funcite de doua criterii. Cristalele se pot forma prin solidificare gradata intr-un flux de lava sau se formeaza rapid in urma caldurii si presiunii impactului. Apoi au determinat varsta cristalelo prin masurarea ratiei de uraniu ce trebuie dusa/condusa. Uraniul are doi izotopi, fiecare descompunandu-se in propiul  izotop conducator, oferind cercetatorilor multiple masuratori pe baza datarii radioactive ce verifica consistenta.

Echipa a analizat meteoritul martian si au gasit cristale mari, conectate, cu o varsta de cca 187 milioane de ani,  fapt ce sugereaza ca roca s-a format acum aprox.187 mil ani in urma unei eruptii vulcanice. 

Cercetatoriiau gasit cristale de zircon care s-au format intr-un  impact acum aprox. 22 milioane de ani.

Schmitt spune ca prin aplicarea tehnicii pe rocile de pe marte, pe luna, pe asteroizi sau chiar pe Pamant oamenii de stiinta pot afla mai multe despre timpul in care au erupt vulcanii in trecutul indepartat.

Providing a tool for unlocking secrets of the early solar system, a new technique accurately determines the age of meteorites, scientists report in the July 25 Nature.

Scientists disagree over estimates of meteorites’ ages because it’s hard to distinguish between when the rocks formed and when they got seared from an impact and flung into space toward Earth.

UCLA geochronologist Axel Schmitt and colleagues began by examining the structure of a meteorite’s mineral crystals, which differs depending on whether the crystals solidified gradually within a lava flow or rapidly after the intense heat and pressure of an impact. Then they determined the age of the crystals by measuring the ratio of uranium to lead. Uranium has two isotopes, each of which decays into its own lead isotope, providing researchers with multiple radioactive-dating measurements to cross-check for consistency.

The team analyzed the Martian meteorite Northwest Africa 5298 and found large, interlocking crystals about 187 million years old, which suggests that the rock formed during a volcanic eruption back then. The researchers also found zircon crystals that likely formed from an impact no more than 22 million years ago.

Schmitt says that by applying the technique to rocks from Mars, the moon, asteroids and even Earth, scientists can learn about when volcanoes erupted in the distant past.

Fractalii in arta (Fractals in art)

M-am gandit sa va mai ofer niste informatii interesante despre fractali :)
Tipare de fractali au fost descoperite în picturile artistului american Jackson Pollock. Deși picturile lui Pollock par a fi doar stropi haotici, analiza computerizată a descoperit tipare de fractali în opera sa.
Iata un exemplu:

Fractalii sunt de asemenea predominanți în arta și arhitectura africană. Casele circulare apar în cercuri de cercuri, casele dreptunghiulare în dreptunghiuri de dreptunghiuri și așa mai departe. Astfel de tipare se găsesc și în textile și sculpturile africane, precum și în părul împletit în codițe.

Exemple de formare a fractalilor (cu obiecte obisnuite)
Un fractal se formează când se despart două plăci de acril lipite. 

Ramificarea fractalilor are loc în cazul suprafeţei DVD-urilor iradiate într-un cuptor cu microunde.

Si: O magnificare a mulţimii phoenix.

I have some extra information about fractals :)
Patterns for fractals were dicovered in Jackson Pollok's paintings.Even if his paintings look like chaotic drops, computer analysis has found fractal patterns in his work.
Here's an example:

Decalcomania, a technique used by artists such as Max Ernst, can produce fractal-like patterns. It involves pressing paint between two surfaces and pulling them apart.
Fractals appear in african architecture. Circular houses appear in circles of circles, rectangular houses in rectangles of rectangles, and so on. Such scaling patterns can also be found in African textiles, sculpture, and even cornrow hairstyles.
 A fractal is formed when pulling apart two glue-covered acrylic sheets.

Fractal branching occurs for DVDs area irradiated in a microwave oven.

And a magnification of the crowd phoenix.

-Ioana

Lumina "sucita" transmite mai multa informatie (Twisted light transmits more data)

Un nou cablu din fibra optica care transmite mai multe raze de lumina simultan poate usura si  grabi drastic viteza informatiei transmise pe internet.

Andrew Weiner, un fizician de la Universitatea Purdue din West Lafayette, Indiana spune ca:" E ca si cum am avea mai multe fibre optice insa fara a avea cu adevarat mai multe"

Companiile de telecomunicatii folosesc lumina pentru a codifica si transmite informatia prin cablurile din fibra optica. In ultimele decenii, savantii au marit latimea de banda prin faptul ca au permis fasciculului de lumina sa transmita mai multa informatie, dar progresul lor va fi depasit in curand de vastele cantitati de informatie pe care oamenii le schimba intre ei. Folosind mai multe fibre ar fi costisitor. Siddharth Ramachandran, fizician de la Universitatea Boston spune ca: "Am ajuns la punctul unde comunitatea telecomunicatiilor a inceput sa intrebe ce altceva am putea face".

Solutia pe care a gasit-o impreuna cu echipa lui este sa trimita mai multe raze de lumina simultan intr-o singura fibra. Aceasta idee e aparut acum 40 de ani , dar nu este un lucru usor de facut deoarece fibrele traditionale permit razelor de lumina ce se misca in paralel sa se amestece incurcand 1s si 0s codate in fiecare fascicul.

Recent, cercetatorii au incercat sa imparta torsiunile in unele dintre fascicule pentru ca ele sa formeze o spirala impreuna cu fibra, in timp ce celelalte circula in linie dreapta, dar nici acest lucru nu a mers.

Abandonand ideea "amestecarii" luminii, cativa dintre cercetatori au creat algoritmi complecsi care descifreaza fasciculele amestecate la capatul cablului, dar algoritmii sunt lenti si nu sunt eficienti 100%.

Pe 28 Iunie, Ramachandran si echipa lui au raportat construirea unei fibre lungi de 1,1 km, care, pentru rima oara, permitea multiplelor fascicule sa ajunga la destinatie intacte. Fibrele lor de siliciu sunt narcotizate  cu alte materiale, fapt ce permite fasciculelor sa se miste la viteze usor diferite si le impiedica sa se amestece.

Folosind un instrument numit "modulator de lumina spatiala" pentru a rasuci fasciculele, cercetatorii au trimis 4 fascicule concomitent, trimitand informatie de mai multe de 1.6 trilioane de biti pe secunda, prin fibra lor facuta la comanda. Ei spera sa comprime mai multa informatie  in fiecare din fascicule folosind metode deja exploatate de industria telecomunicatiilor. Ramachandran a observat ca echipa sa si-a fabricat fibrele folosind metode standard, astfel ca, daca vor fi produse la scara industriala fibra nu ar trebui sa coste mai mult decat cele deja disponibile.

Ramachandran spune ca nu este sigur daca noua fibra va putea fi utilizata pentru a comunica informatia pe distante mari ,dar spera ca va imbunatati transmisia in zonele cu populatie densa. De asemenea va ajuta la vastele servere ale fermelor de informatie, unde mii de computere stocheaza  informatii pentru cmpanii ca Google si Facebook care necesita retele ferme si rapide pentru a schimba informatii.

A new fiber-optic cable that seamlessly shuttles multiple beams of light simultaneously could drastically speed data transfer over the Internet.

“It’s like having more fibers without actually laying more fibers,” says Andrew Weiner, a physicist at Purdue University in West Lafayette, Indiana.

Telecommunications companies use light to encode and send data through fiber-optic cables. Over the last few decades, scientists have increased bandwidth by enabling a single beam to carry more information, but their progress soon will be outpaced by the vast amounts of data people exchange. Laying more fibers would be expensive. “We’ve gotten to the point where the [telecom] community has been asking what else we can do,” says Siddharth Ramachandran, a physicist at Boston University.

The solution he and his team came up with was to dispatch multiple beams of light through a single fiber. The idea goes back nearly four decades, but it’s not an easy thing to do because traditional fibers allow light beams moving in parallel to interfere with each other, jumbling the 1s and 0s encoded in each beam.

Recently, scientists have tried imparting twists into some of the beams so that they spiral along the fiber while others travel in a straight line, but that hasn’t worked either. Resigned to this light mixing, some researchers have created complex algorithms that decipher the amalgamated beams at the end of the cable, but the algorithms are slow and not 100 percent effective.

In the June 28 Science, Ramachandran and his team report building a 1.1-kilometer-long fiber that, for the first time, allows multiple beams to reach their destination intact. Their silica fiber is doped in places with other materials, which cause the beams to move at slightly different speeds and prevent them from mixing with each other.

Using an instrument called a spatial light modulator to twist the beams, the researchers sent as many as four concurrent beams, transmitting data at speeds up to 1.6 trillion bits per second, through their custom fiber. They hope to squeeze more data into each of those beams using methods already exploited by the telecom industry. Ramachandran notes that the team manufactured its fiber at a commercial facility using standard methods, so if it were mass produced, the fiber should not cost much more than those now in use.

Ramachandran says he is unsure whether the new fiber will work for communicating data over long distances, but hopes that it will improve transmission in dense metropolitan areas. It could also help in vast data server farms, where thousands of computers that store data for companies like Google and Facebook require tight, fast networks to exchange information.