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» Glavni naslovi






Twenty years of "Planeta"

At the beginning of the summer of this year, two decades have passed since the first issue of the magazine "Planeta", an edition that had two important determinants in the header of the front page: "Galaxy" and "Magazine for Science, Research and Discovery". These determinants point, first of all, to the fact that this magazine follows the path of a paper that was once very popular throughout Yugoslavia, and was concerned with the popularization of scientific and technical achievements.
The paper is published every two months and always has 68 pages. So far, 112 issues have been issued. On the edition's website, you can find information about the interest of readers from areas that are not reached by printed copies and in which there is a lively interest in the content of the paper, so you can find out that the site has been visited by readers from 193 countries of the world so far, and that, on average, the site it is visited every day by more than a thousand interested people, mostly readers who know the Serbian language.
It is estimated that over half a million copies of "Planeta" have been printed so far, two decades after the first issue appeared. Slightly more than half of the articles published are those written by local journalists on local topics. A book of 7,616 pages in A4 format could be made from the texts published in "Planeta".



Only in "spiral galaxies"

Not so long ago in 2007, the first "earth-like" planet was discovered - Gliese 581C, which is only five light years away from us. Certainly, one of the many questions related to this discovery was whether there is life on it, is it intelligent or is it only at the level of single-celled organisms? The discovery of the first planet outside our solar system led to other questions, very significant for us, such as: whether some of the interstellar civilizations have already tried to contact us, without us recognizing the signs they send us; perhaps we are not looking for them in the right places or paying attention to the right things; maybe these beings are too "alien" for us to be able to communicate with them; finally, they may have decided to be a non-technical civilization; perhaps civilizations do not last long and it is in the nature of intelligent life to destroy itself or to destroy others; maybe they deliberately avoid contacting us or maybe they simply don't exist!
One of the questions that has haunted the human race since time immemorial, apart from the question "is there life after death", is certainly also whether we are alone in the universe as the only living beings in this vast expanse? If so, the entire universe would be ours only, so we can do whatever we want, arrange and change it according to our needs. Spreading life across this infinity, we might one day become something akin to gods.



As fast as possible through space

The American agency for advanced research projects in the field of defense, better known by its English abbreviation DARPA, within the framework of the DRACO project, together with NASA, is working on nuclear propulsion technology for spacecraft, with the goal of producing the first test aircraft and testing a nuclear engine in space by 2027.
Current rocket propulsion technology uses chemical fuels. The propellant is ignited in a controlled manner, during combustion it is directed through the nozzle and thus thrust is generated. Methane, hydrogen and highly purified kerosene are mostly used as liquid propellants. Since there is no oxygen outside the atmosphere, rockets, in addition to fuel, must also carry oxygen for combustion in their tanks, and most often in liquid form (eng. LOX, liquid oxygen). The fact that both the propellant and the fuel must be carried increases the mass of the rocket.
Logically, we have been looking for alternative means of propulsion for decades. Many more modest alternative propulsion methods for spacecraft, such as ion propulsion powered by solar sails, are more suitable for probes, or small unmanned research vehicles that are launched to other planets in the solar system to collect scientific data. When it comes to manned spaceflight, chemical fuel propulsion is still the way to go.



How much does it cost to send an email?

On the eve of winter, the first question that arises is: how will we keep warm? And for many, the next thought is how to provide uninterrupted power supply for computers and access to the Internet, without which our life has become almost unimaginable, and for many it is a daily necessity, a basic tool for work and ensuring existence. In addition to the fact that it is important for the operation of computers, how much electricity do we actually spend on the Internet and digital technologies?
The consumption of electricity for the operation of the computers we have in the house is not something that comes to mind when the electricity bill arrives. It is even more difficult to imagine that one click on a link on the Web consumes any energy at all.
However, the image, video, or any content that appeared on the screen with such ease had to be somehow delivered to our device. A simple click of the mouse or touch of the phone screen sends an invisible signal halfway around the world and orders from the server exactly that image, exactly that content that we wanted; the content is then sent through a network of copper wires and optical fibers, through hundreds of devices, routers and amplifiers, maybe even goes into space to a satellite and returns to the other side of the globe, or dives to the bottom of the ocean and passes through an optical cable, and back through a new set of cables or, directly, into the ether of mobile and WiFi networks, so that we see a picture of a cat with a funny message on the screen of our device. Some energy had to be expended for such a long journey of one image.



Replantation microsurgery of the upper extremities

The Californian space company "Relativity Space" has been making rockets using 3D printing technology for eight years. The use of 3D printing technology is widely present in the space industry, both for the production of tools used in space and for the production of rocket parts. However, no company before this has designed, produced and launched a rocket based on a fully automated production process based on a computer model. The company's offering currently includes a disposable "Terran 1" rocket powered by their 3D printed "Aeon 1" engine. A reusable "Terran R" rocket is being prepared, which should be ready by 2024. It will be powered by the new "Aeon R" engine.
The rocket-building approach used by software companies in the last few years has proven to be a path that brings rapid innovation. Namely, in the second half of the 20th century, traditional space companies, which for decades received contracts from NASA or the US Department of Defense, adhered to the traditional approach to design. This meant that the design of the aircraft was perfected for years and that only at the end was the prototype made. Thus, many potentially revolutionary projects were canceled even before the creation of prototypes due to the change in the fiscal policy of the current administration. Also, in some cases, the projects reached the stage of making a prototype, but the project was canceled due to defects that would have been revealed during testing. The paradigm shift that took place in the last fifteen years, mostly thanks to "SpaceX", has meant that private space companies are no longer mere contractors for US or other government agencies, but rather autonomously design and implement new projects.In the Acibadem Bel Medic General Hospital in Belgrade, an unusual undertaking was recently performed to stitch (replant) an amputated thumb to a patient who had experienced a traumatic injury. It is a very demanding microsurgical operation that is usually performed only in rare specialized, large hospital centers and which requires enormous microsurgical knowledge and experience. The operation was performed by prof. Dr. Čedomir Vučetić, specialist in orthopedic surgery with traumatology, one of the pioneers of microsurgery of extremities in our country, in cooperation with MD. sc. Rodoljub Stefanović, an experienced anesthesiologist in that surgical field.
The special significance of the procedure is that this type of operation was performed for the first time in a private hospital, and given the fact that limb replantations are performed in specialized medical centers that even smaller countries often do not have, according to Prof. Vučetić. Equipping such centers requires significant financial resources, and even more experts competent in that field, so this surgical intervention demonstrated all the organizational, technical and personnel capabilities of the mentioned institution, the existence of conditions for performing even the most demanding operations, something that is not common practice in private hospitals in Serbia.
Prof. Čedomir Vučetić, who highlights these qualities of Acibadem Bel Medic, is a world-class expert. His professional specialty is that during his working life, in addition to microsurgery, he also mastered the famous Ilizarov method of bone elongation, and the principles of treating bone infections, and combined his knowledge in these three major areas into one exceptional work practice, which resulted in a series of fascinating cases of replantation. arms, hands and/or fingers.



Should and when to operate the tonsils?

Too frequent acute infections of the tonsils can develop into a chronic inflammatory state, with significant consequences for the growth and development of a young organism, so surgical removal of the tonsils is considered as a therapeutic solution in such cases. Dr. Bojan Marković, specialist in ENT, allergology and clinical immunology, points out that the criteria for setting an indication for tonsil surgery are very strict today, but also that obstructive nocturnal breathing is an absolute indication for the removal of all three tonsils.
At the beginning of the 20th century, even in the most developed countries of the world, it was considered that the tonsils were evolutionarily outdated and almost unnecessary, so they were almost inevitably surgically removed in children. In the mid-1940s, in New York, as many as 60 percent of school-age children, as well as almost 40 percent of all other children, underwent tonsil operations.
Opponents of that trend warned about the immunological significance of the tonsils and advised that they should be kept whenever possible, but the rate of tonsillectomy decreased only in the early eighties, with new scientific evidence that the absence of tonsils is not as beneficial as previously thought.



Human and sweet as chicken

Cannibalism (Sp. Caníbal - man-eater, cannibalism) is a name that comes from the Spanish word for the name of the Karibis people, from the Lesser Antilles, who used meat of human origin in their diet. The established figurative meaning of cannibalism is ferocity, inhumanity, savagery. The concept of cannibalism in its original form included only the human race, and was later extended to animal populations. Cannibalism is the act of consuming an individual of the same species, in part or in whole. Cannibalism was once thought to be characteristic only of praying mantises and black widows, and to be caused solely by lack of food or stress. Today, it is known that in the animal kingdom it is present in several hundred, maybe even thousands of species and that it has numerous functions, which are often useful for the entire species. Eating the same species, or exhibiting cannibalistic behavior, is a relatively common ecological interaction in the animal kingdom, and has been observed in more than 1,500 species.
There are active and passive cannibalism. Active cannibals devour relatives they have caught and killed. Scrolls are mostly cruel predators. Firefly larvae feed on species much larger than themselves - most often they eat snails and worms - by slowly decomposing and sucking them. However, there are also those who will happily eat other types of fireflies that they have outsmarted and tricked - by mimicry.



Mysterious fossils in the Baden Sea of Serbia

More than 14 million years ago, during the Middle Miocene (Badenian), Višnjica near Belgrade was part of the southeastern rim of the Central Paratethys sea from a paleogeographic point of view. Geotectonically, it belonged to the Pannonian Basin, which covers an area of about 400 × 800 km. It is often interpreted as a Mediterranean backwater basin of the middle Miocene that was surrounded by the Alps, the Carpathians and the Dinarides. This sea directly flooded the Upper Cretaceous or Lower Miocene sediments in Belgrade and its surroundings. Various organisms such as foraminifera, ostracods, echinoids, bryozoans, corals, gastropods, bivalves, cephalopods, crustaceans and fish inhabited the marine environment only to be covered by silt, sand or mud after a while. Soon, the habitat in Višnjica, at the confluence of the Ramadana stream and the Danube, became their mass grave, built of clay that is blue when wet.






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