We turn to the section How it works... to speak about the functioning of the television. The silly box, since they name it some, takes with us about 50 years, but his first steps happened it does more than 100. From these first steps with the Nipkow disc until our days with the sophisticated screens SMELL there has been a long trip, and obviously we are not going to speak about all the contributions that the science has done to improve the television, but yes that we are going to treat two models: the television CRT and the television of plasma. The television CRT (initials in English of Pipe of Cathode Beams) it is the first one that many of the readership will identify with the television "of the whole life". This gigantic box with a thick screen of crystal and that, occasionally, if the sign was going away he was managing beating him in the side street. The same technology was applying itself also for the monitors of computer (they keep on existing but less and less) so this explanation is extensible to monitors. Inside this type of television there is a device called pipe of cathode beams (we will be quick like CRT) which functioning we are going to try to explain simply. The CRT is composed on different parts as we can see in the top figure. We have to the left a cannon of electrons (cathode) that is throwing them continuously against the screen, to the right. To half of the figure there can be seen a few bobbins that work as magnet to focus and to direct the electron to the point of the screen that we are interested in. To obtain this also one is provided with several plates. The screen is a layer of phosphorus that is illuminated on having received the impact of the electron. Seen this way perhaps it is a little complicated to do an idea to him so we are going to mount ourselves in an electron and do the whole process. Everything begins when it departs from the electrons cannon. Of beginning his trip it is already focused and directed to the little to the screen thanks to the bobbins and the plates. This first electron will go away direct to the left top corner where there is a small pixel. The pixel is composed of three different areas: red, blue and green. Depending on the intensity that applies him to itself to each of these three areas we will see on the screen a pixel of a color or other. Now then, this is only a pixel, we can only refill the millions that the screen has. The following electron will continue the same way that should be safe for a small modification that will take him to the position of the contiguous pixel; the first horizontal pixels tier being refilled thus. Realizing the same process for the rest of tiers the image is obtained finally. All this process realizes at a major speed that the one that the eye can appreciate and therefore it seems that we see a completely animated image when really what appears is a set of pixels that freshen up several times per second, what is known like frames for second (fps). After knowing the functioning of a screen CRT let's go on to the plasma screens. These screens are already more modern, although the basic functioning is not very different from that of the CRT. How we can see in the low scheme it is a question of a counterfoil of small blocks or cells of color between two glass walls. Every combination of 3 colors, which are red, blue and green as in the CRT, they form also a pixel of the image. Now we do not have a pipe of cathode beams if not that the mechanism to produce the photons (light) is lightly different. Inside the colors cells a noble gas is confinedas it can be the xenon, the neon, or the helium, which is ionized to produce light. The way of ionizing it is to apply a potential difference to him using the electrodes that exist ahead and behind every block. Thus in the gas there can appear an electric current that, on having come to the phosphorus of the cells, produces a photon of the certain color. Thus applying a potential difference to the set of three cells that shape the pixel million colors can be generated with relative facility. After all, this method well can be alike how a fluorescent lamp works, but we leave that for another day. Multitude of different screens exists with funcionamientos more or less sophisticated, but I believe that with these two, which perhaps are the most well-known, it is sufficient. Therefore not at all more up to the next delivery of How does it work.... Greetings ;) Of what does the Spanish vaccine consist against the VIH The truth of the fluorescent ones
I have begun a project with pupils of my insti (and quite the one that wants to join) concerning the addictions.
We are going to leave some "addiction" (each one his: the computer, the console, the TV, the chocolate, the tobacco or what should be), and we are going to be writing a blog to tell how it us goes and to do a little of “therapy of group”.
If you mola, it would be entertained to be provided with you. It is going to be one month (we start tomorrow on Monday), and insurance that it is an interesting exercise.
And if you do not take part like collaborators, since happen over there, read to us, mention to us and treat us tenderly that we are going to be very sensitive …
It is an example to foresee numbers between 0 and 63
You need these letters
(We leave some reader crush you, to design a few nicer stage to us)
You will have to forgive me, but a kind reader has indicated me that one has strained an error to me in the LETTER 2. Where it puts 8 it must put 6
Now you ask your "victim" to choose a number between 0 and 63
Later you are teaching him the letters and ask him if his number is in each of them.
If he says to you that yes, you should plunge mentally the first number of the letter.
When you have taught him all the letters, the sum that you have done will be the elected number.
Let's do an example.
The elected number will be 47
Is it in the first letter? Yes (I plunge 1)
Is it in the second letter? Yes (I plunge 2, whole 3)
Is it in the third letter? Yes (I plunge 4, whole 7)
Is it in the fourth letter? Yes (I plunge 8, whole 15)
Is it in the fifth letter? Not (I do not plunge 16, I am still conl 15)
Is it in the sixth letter? Yes (I plunge 32, whole 47!!)
Ta chaaaaan!!
And now the explanation
In the conjuring tricks, when they "foresee" something to you it is for one of these two skills. Or they force you to choose what they want, or force you to reveal your election.
In our case... they have made you "sing" the number as a goldfinch... gullible!
"If I have not said anything..." - you will protest.
Yes, son yes... what it spends is that you speak in BINARY.
You have said: Yes, yes, yes, yes, Not, Yes...
What can be understood like 1,1,1,1,0,1
47 in binary is 101111... This way of simple.
How to do the letters
In the first letter you put all the numbers that they have the first bit to one
In the second letter those that they have the second bit to one... etc.
Here you have a table of the first 64 numbers in binary
With this you can already do to yourself yourself the letters that you want, according to up to the number that you want to cover. With one more letter you can come up to 100 (in particular up to 127), but you have to include more numbers in the six first ones using the skill that we have described.
Have you ever been in a discotheque or in a concert and have seen any laser of green or red color? That rascal, but: have you ever thought about if it was sure for our sight? If they it use in a public place debit of it being: no? In this entry we are going to try to answer to this question. But earlier … What is a laser? We have extracted the definition of the NTP 261 of the INSHT, since it defines it of precise form and briefly. According to the technical prevention note 261 a laser is defined of the following form: “The láseres are devices that produce and amplify a bundle of electromagnetic radiation in the interval of wavelengths of 200 nanómetros to 1 millimeter, like result of a controlled stimulated emission. The obtained bundle of radiation of this form has three properties that separate it from the obtained radiation of conventional sources. It is monochrome (of a concrete wavelength), it is coherent (all the electromagnetic waves coincide with phase) and it is expressed in a certain direction (with very small angular difference, so that the dispersion of the bundle is not significant with regard to his length)." The characteristics of a laser as the following ones are the NTP 261: wavelength of emission, duration of the emission, potency or energy of the bundle, diameter of the bundle and difference. So that you should do better an idea, we are going to be explaining the principal characteristics of the laser, but earlier we are going to try to understand how a laser works. A laser (initials in English of “amplification of the light by means of stimulated radiation emission”) consists of different parts that possess different properties and functions. To start we need what is known as an active way (1). It is a question of the chemical compound that is inside the device and that we will excite so that it expresses the light laser. To produce the excitement there is necessary an energy source (2), which is usually a battery, to produce the energy pumping. Once exitados the atoms, the external electrons droop and they begin expressing the first photons. And here there begins real stimulated emission that names the laser. The walls of the active way are two reflecting mirrors. One of them is reflecting to 100 % (3) while other (4) presents a small transparence. The photons bounce infinity of times between the mirrors and in every step along the active way, if they collide with an excited electron this one droops and expresses another photon. This process realized constantly produces a big number of photons with the properties of coherence and without phase lag, which we will explain further on. And after all this almost instantaneous process there is generated the bundle of the laser (5) that goes out for a small gap in the mirror (4). The wavelength has no loss. His color talks each other of the wavelength of the light that expresses the laser, that is to say. They are, between slightly secondhand others, in red color (630 nm), in green (532 nm), in violet (405 nm) and even in infrared that is not visible for the human eye (808 nm). Generally every laser works with a certain color (it is monochrome) that depends on the chemical compound that is in his interior and that produces the bundle. Different types of laser exist as the way of expressing that they have. By agreement the time of extreme emission is chosen between a laser of continuous emission and one of emission touched in 0,25 seconds. If the pulse of light that expresses the laser is expressed in more than 0,25 seconds it is considered to be a continuous laser, while it does it in less time he is considered to be touched. For the user scarcely there is difference, but in practice yes that it is. For example, the touched láseres are useful in the materials ablation when you want vaporizar a small material portion. With a short but intense pulse you might do it, while with a continuous laser the energy would vanish for the rest of the material without achieving the looked vaporization. The potency or energy of the bundle indicates us the grade of power that has the laser. Major how much is the potency, as well as the energy, more dangerous will be the laser, since more power will have to "burn" the materials in which it affects. For example, the top laser that the speakers use in a conference generally does not overcome 5 mW, what makes them quite sure, but a laser for astronomical observation of 100 mW expresses with more power and it is capable of causing serious damages. Further down we will see a video of a laser of 125 mW in action. For the continuous láseres it usually give the potency in watts, but for the touched láseres another form exists. It is a question of Julys divided per time. For example, if we say that a laser is 150 mJ/10 ns it means that the laser expresses 150 milijulios in pulses of 10 nanoseconds. The characteristic most emphasized from the láseres is few dispersion that he suffers. Any bulb expresses a light in all the directions of the space, while a laser expresses a bundle in the only direction. This owes to the coherence of the light that it generates and to that is cofiled perfectly. The coherence is only a property of the waves for which these support a difference of constant phase, what in our case comes to say that all the expressed photons have the same phase. This, together with the colimación, which consists of doing that all the photons have the same direction (they point towards the infinite), it does that they do not interfere between themselves and that the bundle is supported during more distance without dispersing. For example, the bundle of a laser normalito of He-Ne pointing at the Moon only expands 1,6 km (diverges) in 384.000 km that it covers. A property that arises from that the bundle of the laser diverges little and of his potency is that it can go so far as to burn the materials in which it affects. This is due to the fact that the area that receives the impact warms up like result of the continuous reception of photons focused in a very small area. It is similar to when we take a magnifying glass and focus on the beams of the Sun in a small point. The material on which we focus (an ant if we are bad persons:P) can go so far as to be burned by the sufficient exhibition time. The láseres of 100 mW are already sufficiently powerful as to be able to burn small things as role or make to exploit balloons (pointing at some area of black color). The most powerful láseres of several W are already used to cut wood and those of even major potency to cut metal. We leave you with a video in which it is possible to see what a laser of 125 mW can do.
Are they dangerous the laser that is used in public places as in discotheques? The technical note in prevention 261 says this way: "the aptitude of a laser to produce a risk will be determined principally by the first three factors: wavelength, duration or time of exhibition and potency or energy of the bundle.” As we were mentioning that more above with láseres of 100 mW we can already burn things. In different experiments there have put themselves to the test different types of laser and his aptitude to cause observable damages in the animals retina. Let's remember that the part of the human body that more risk has opposite to the possible damages of a laser is the retina. For example, with a laser of 74 mW it is possible to hurt with a time of exhibition of 2 milliseconds in a Monkey Rhesus, while 20 ms was needed with a laser of 36 mW of potency. A Krypton laser with a wavelength of 586,2 nanómetros and a potency of 22,5 mW produces damage with a time of 33 ms exhibition and with 25 mW if it is exhibited during 16 ms. Even with a laser of 10 mW damage takes place with a time of exhibition of a second. Now we go to the articles laser known. So that we do an idea, a top laser to ourselves to indicate things in a conference, it can have in most cases between less than 1 mW and 5 mW (as we have commented previously). Even with a potency of 5 mW they can go so far as to hurt with a long exhibition time. In adults it is supposed that the same act of separating the look is a sufficient protection, but in children clinical cases have happened with reversible injuries for a long exhibition (approximately 10 seconds, producing edema to him to blacken). An exhibition prolonged with this type of láseres might produce of course permanent damages also. But: How much potency do the láseres of the discotheques have? There are very varied ones, but to do an idea to us, they are for example of 10 mW, of 30mW, of 40 mW, of 80 mW, even of 350 mW. You can imagine what this type of láseres can do to him to our sight: no? To simplify a little the things, the láseres as they gather together his danger grade in different categories, as 654 turns out to be reflected in the technical prevention note. This way we have left the following categories: type 1, 1M, 2, 2M, 3R, 3B and 4. We have found papers that he accompanies to some of these devices like cards and instructions. After reading the indications that appear in some of the devices that are used to generate animations laser in discotheques, we could have verified that the majority they turn out to be catalogued in the proper instructions of the device like laser of type 3B (although they are also of type 3R or 4 for example). To know what that means we can come to the technical note in prevention 654, where the following thing appears in the type 3B … ”The direct vision of the bundle is always dangerous, while the diffuse reflection is normally sure”. In fact in the same instructions of some devices it is warned in the shape of text that the lightest direct radiation is dangerous for the sight and can cause permanent damages in the retina. An interesting study must exist round there precisely on láseres of discotheques. They quote it in different places as in the BBC and in consumer. We can extract some parts, although more interesting it is to bring in and to read these pages. For example, on the page of the BBC (here in Castilian) we can read … “Lasers used in nightclubs could damage dancers' sight, researchers have warned.” And of that of Consumer … “The popular lights laser that are used in the discotheques or night clubs of half a world can affect to the vision of the persons who frequent this type of places, according to a report of the Meeting of Radiological Protection of England (NRPB in his initials in English) quoted by the BBC.” We can see more information about the topic here... But: how they put these láseres in public places!? Moreover: how they allow that to be made!? An important point is that the láseres do not produce damages if they are used correctly. One of the principal problems can come for his undue use. The manufacturers have obligation to accompany the device of a few instructions of use between other things. Here we can read on the topic. Reading the manuals of some of these devices, in them it is said clearly that the laser bundle must not settle in such a way that it gives straight to the eyes of the persons (in addition to other specifications, like which there must exist the figure of an expert in control of laser … etc …). If a slightly powerful laser will be used or the installed system one had such form that the radiation laser that was coming to the public was not overcoming the established limits, from the point of view of the risk it would be correct. But what is clear is that what it is not necessary to do is to use a powerful laser and to direct it straight on the persons. If the businessman does not use of suitable form this type of technology, it can achieve that the sight of the user finishes damaged. Frequently it might happen that or the businessman uses badly the device or sometimes even it does not even receive the information adapted about his functioning. In some cases if the laser is the sufficiently powerful thing, it is possible to go so far as to produce a real disaster. Do you remember what happened in Russia in a concert? Since that itself. It began raining and the "technical staff" thought that he had not greatly sense to point with the láseres at the sky as they were reckoning, since they had covered the dance floor and this way “the beams” were not going to be seen. So they aimed at them straight towards the dance floor. The láseres must perform high potency, I suppose that of class 4, for the effect that took place in the sight of the assistants of so sharp form. The news as pais.com … “Tens young people who took part last July 5 in a music festival dance outdoors close to Moscow they have lost part of the vision after the laser used during the spectacle was burning his retinas, have admitted Russian sanitary sources, that they have confirmed 12 cases.” “"Partly this has owed to the rain, but also to the ignorance of the technical staff, by force of the used, extremely powerful laser for a small space as the place in which the concert was celebrated", has shown Valentin Vasiliev, owner of a company of rent of cannons of laser. Meanwhile, the promoters of the festival of electronic music keep silence, while the local authorities affirm that they never went so far as to receive an authorization request to celebrate the event, according to the digital newspaper Gazeta. Ru.” “"What you saw there were annoying spots, like when you look at the sun", he has said to Kommersant Dmitry. "After three days, I went to the hospital. The doctors examined me and asked me if it had been in the festival. I agreed, and they deposited me straight; I could not to house take my things again", he has reported.” The ocular damage We were saying that the part of the eye that covers more danger is the retina and that the produced damage depends straight on the energy of the bundle laser. But, what more factors influence the appearance of the burn?. On the other hand, although the retina is the textile that has more possibilities of be damaging: cannot other ocular structures fall ill with the laser? The key is in another parameter that we have mentioned at first: the wavelength. We were saying that for the proper nature of the laser, they are monochrome or almost monochrome. Namely they have only one wavelength, only one color. In the visible bogey of the electromagnetic radiation, the optical structures of the eye (cornea, watery, crystalline, glassy humor) are transparent. Namely the light does not intergesticulate with them. With the laser the same happens: if the laser is visible (that is to say, his wavelength will be minor than the infrared ones and more than the ultraviolet ones) it will cross the cornea, the crystalline one and the humors of the eye without affecting them, although the energy of the bundle is high. For example, a blue, green, red or yellow laser of 500 mW, that with this energy is very dangerous for the eye, will not burn the cornea or the crystalline one. Of general form, it is accepted that to energy equality, the laser that more damage produces in the retina is that 550 is next to nanómetros (green color). But we understand that any visible laser (and infrared of of short wavelength) they can affect to the retina. On the outside of the visible bogey, the things change. In the infrared near one to the visible light, there are still supported the optical properties of the visible light: the optical structures keep on being transparent, and the infrared radiation still comes to the retina. In fact, there are medical tests that use infrared radiation to study the retina: the angiografía with green indocianida, and the scanner of optical coherence (the last one uses in fact an infrared laser). For the infrared radiations of major wavelength (in the bogey, more removed from the visible light) the optical means are already not transparent. And with the ultraviolet light the same happens, the eye is opaque and the radiation does not come to the retina, stays in the cornea. These characteristics take advantage in ophthalmology: if we want to use a laser with an effect in the cornea, as it happens with the surgery of the myopia, the ultraviolet bogey is used. Therefore, already we take the principal reason as that the habitual láseres (that are in the visible bogey) affect to the retina. Also an interesting effect takes place: the transparent means of the eye are in charge of focusing and concentrating the light beams on the retina, from this form the projected image originates. If we point with a laser at the eye the same happens: the lenses of the eye concentrate the energy of the laser on a minor area of the retina, therefore there takes place major damage (more energy in minor surface, major thermal and photochemical effect). Well, already we have a bundle laser of the visible bogey that crosses the transparent textiles of the eye and comes to the retina. What happens then?. Most of the textile retiniano is transparent, and the laser crosses it up to the most external part: the epithelium pigmentario and the fotorreceptores. This area has pigments that prevent the transparence. The photons then interact with the textile. A principally thermal damage takes place (although to very high energies a photochemical damage takes place), the temperature increases suddenly several grades, too rapidly so that the mechanisms of thermal dispersion act. The heat propagates to other more internal layers of the retina, and to adjacent retina areas. Factors that are going to determine the visual damage Most of the burns retinianas for the laser does not cause a valuable visual loss. Namely it affects in little or not at all the visual function. This the ophthalmologists know it very well, because for a series of illnesses of the retina (principally as regards the diabetes), sometimes they have to produce small burns for almost the whole retina, and the patient does not notice any visual loss. This is like that because the thin vision, which allows us to visualize the detail, corresponds to a small surface of the retina, the most central, which it is named fóvea. The impacts laser (both accidental and therapeutic) far from the fóvea are not going to produce visual problems: the peripheral retina corresponds to the peripheral visual field, which has spatial resolution small, and a loss of sensibility produced by a burn is not translated in effects biologically excellent. [I always speak of láseres with energies of the parameters that we have indicated more above, how maximum of a few hundreds of milivatios. Some industrial láseres of major energies yes can produce major damages in peripheral retina, like hemorrhages or perforations retinianas]. If the light impact affects in the fóvea, the things change: any permanent damage is translated in an irreversible visual loss. The retina here is thinner (less dispersion of the heat, more damage in the textile), the epithelium pigmentario is darker (more light absorption, more damage) and the fotorreceptores are much more nearby between themselves (major number of fotorreceptores damaged by surface unit, less spread between them to remove the heat). A light is projected straight in the fóvea when we look straight at this light. Therefore, the most dangerous thing when a device laser points at the eye, it is to look at it straight. It is a reflex: if something pays our attention in our peripheral visual field, we focus it straight ahead, and if it is a light laser exhibit our fóvea. But not all sound disadvantages. The same as we have the reflex of looking straight ahead at a light, also we have other of us to separate when this one dazzles us. The láseres that are used in the discotheques work in the visible bogey. When the fóvea turns out to be dazzled, we have a protection reflex that separates the eye, it closes the eyelid and even can turn the head. So used laser depends on the system the direct exhibition might hurt. For speaking with the numbers in the hand, an answer of habitual dazzle limits the exhibition of the fóvea between 0,15 and 0,25 seconds. For a top laser, which has few potency milivatios, it is more than sufficient. The leader would be risked to leave for example in hands of a small child, that playing yes that his fóvea might exhibit during several seconds. A leader of 5 mW would need an exhibition foveal concerning 10-20 seconds. For the láseres of the discotheques mostly of class 3B, a reflex of normal dazzle might go so far as to hurt (let's remember that experimentally with a time of exhibition of 16 milliseconds damage takes place with a laser of 25 mW of potency and is not so rare to find devices of more than 30 mW in the rooms and holiday). A more simple-minded answer (let's think about the relative visual disorientation for the lighting conditions, if the subject has taken alcohol, etc) can be translated in a burn of the fóvea. Other less important factors exist. The diameter of the pupil influences, so that when the pupil is wide (as for example in the discotheques or any slightly illuminated environment) the damage will be major. Those of darker race have more possibilities of turning out to be damaged, because the epithelium pigmentado of the retina, as the skin, will be more pigmentado and will absorb more radiation. And the graduation defects (like the myopia or the farsightedness) act like protectors whenever one does not take glasses or contact lenses: it implies that the laser does not focus well in the retina. And the injuries, why are no many any more people with ocular injuries due to the láseres of discotheque? There are several motives for which finally the injuries might not go so far as to take place or might not go so far as to be notified. One of them is that in the experiments in laboratory and the industrial accidents, the distances are 1 or 2 meters, while in the discotheques most of the people might be at major distance. Another reason might be that most of the people do not look straight to the bundle at laser, as we mention above, or that the fact of separating the look in some cases could be sufficient. Or the injury might go so far as to take place but for ignorance not to relate it to the exhibition to laser. This document is interestingwith these and some other notes on this point. Anyway everything depends on the potency of the laser, of how it is installed, the exhibition time... the commented previously we go. And it is clear that with the suitable laser and the opportune conditions the injuries might go so far as to take place, as it happened already in the concert of the disaster. In short: to look at a laser straight straight ahead during a long time, in a slightly illuminated environment, there will be the most dangerous conditions. And we know that the láseres used in discotheques can use energies that we already consider to be dangerous if they aim at the people instead of to the walls or the roof. Therefore, when less avoid to look straight at the bundle laser, and if it happens, separate quickly the look. Written by Wis, Ocularis and Héctor. Sources Wikipedia NTP 261 NTP 654 BBC BBC (in Spanish) The Country Consumer Lukor Consumption Source image Laser eye insult. Barkana Y, Belkin M. Surv Ophthalmol. 2000 May - June; 44 (6):459-78. Review. PMID: 10906379 [PubMed - indexed for MEDLINE] Microorganisms: that do not take the sandwich from you! What hides the series "Heroes"? Streaming Desperate Housewives S06E17 Chromolume #7 now
The whole world we have our puntito friki. Included doctors. And if you do not believe me, throw a glance to the following T-shirt: You can see it to quí in Street Anatomy. Certainly, this drawing is nicer and perhaps more anatomical than the man without Actimel stomach: truth? ;)
Of course more than once you will have heard like pupil or like teacher "Why there serves to study this, what application it has". Well, today I bring to you a good motive for studying Physics with desire and fondness. Let's see: if I say to you "blood pressure and law of Laplace:" how many of you are you capable of relating both concepts? I put myself a moment the disguise of blue bug comegalletas and I you it count step to pasito:1. The blood pressure is the force with which the blood circulates along the blood glasses. 2. The arterial tension is the force, the resistance that the blood glasses put up against the step of it bleed 3. We lack the third element: the radio of the blood glasses. Do you remember when érais children and jugábais to press a hose and to see how was the water going out to major pressure? 4. Let's go now for the Laplace law: The pressure is equal to the tension divided by the radio. I dress of nice form: Throwing a glance to the equation we realize that if it diminishes the radio, the blood pressure increases and if it raises the tension, also it raises the pressure. With these notes you already have material sufficient to throw yourselves to think what happens when a pesona suffers aterosclerosis (the arteries become more rigid) or any other example related to this that occurs to you. I wait for you in the comments to debate and to explain why of the things. Dedicated tenderly to Sergio L. Palaces, Wis and Eugenio, in so many good moments that have met to me on his earnings on Physics :)
Entry published previously in Science in the XXIst. To children of any age, adolescents and adults it is easy to show them the marvels of the electrostatics simple with experiments that can be done at home. If you touch a friend and feel to a cramp nothing it has to do neither with positive energies nor divine auras. It is, simply, electrostatic. Electrical pendulum It is the simplest thing that serves itself in electrical experiment, after a boli bic rubs in the hair and to bring it over to small role pieces. There consists, simply, of a little boll of porexpan polystyrene (in many books they say elder marrow, as if it was something that is in the supermarket or in the quisoco of the corner) hung by a thin thread. On having brought over a rod of vídrio or of plastic, the sphere is attracted. It leaves that it sticks, you will see that to a little time is repelled. It is due to the fact that the load that the rod adopted as rubbing is distributed between the above mentioned rod and the little boll, until two bodies have the same load. And we already know that bodies with the same load to be repel. If the experiment wants to recur we must touch the little boll, pair unload it. Calm, that you do not electrocute yourself.
Electroscope Designed by Gilbert, this simple device allows us sabersin difficulty if a body is loaded or not. In this video he explains himself marvelously, so there it stays. And you can see this linkage to construct one at home.
Versorio It is very similar to the electrostatic small mill, which allows to see clearly the effect of the tops. The charges tend to accumulate in the areas where there are tops, and in the surface of the driver. That's why the lightning rods have the form that they usually show.
Others
If you take a plastiquito of the envelopes of lime tree and rub it, you can give it in a smooth wall and leave it there for hours.
The mythical experiment of the pen and the roles does not need explanation, although any pupils come to 3rd from THAT without never having realized it.
If you rub a balloon in the hair or in the clothes you can do the same that on of lime tree, to give it to the wall. The balloon pegón lasts less adhered to the surface for a simple reason: the weight.
If nothing sticks to the teflon: How does he adhere to the frying pans?
First it is necessary to tell that it is the teflon. The teflon, it is the trade name registered by DuPont to refer to the politetrafluoretileno.
What hides under this product that seems to repel all the meals remains is about his molecules. The fluorine that wraps them repels almost any material and prevents these from adhering to the teflon. Not in vain, it has the lowest coefficient of friction of the materials that we know. Another fundamental characteristic is his impermeability.
His history is well curious: Roy J. Plunkett (right in the image) and his assistant Jack Rebok (left in the image) they realized experiments for the company DuPont somewhere near the year 1938. In one of them, they wanted to obtain major quantities of tetraflouretileno (TFE). This material, after a simple treatment, was vaporizado and it was happening across a few pipes and meters of flow, later to finish in a camera where other chemicals were applied to him so that it was reacting. As in many other inventions of the history, the find was fortuitous. They detected an error in the system and the motive was not explained. On having dismantled some valves, they realized that there was a white substance in the shape of dust. The TFE there was polimerizado. They tried with many acids and dissolvers, but they did not achieve that it was affecting to this polymer. Then, the history we already know it. The DuPont was interested and happened to be part of his scale of polymers.
But as is the teflon fixed to the frying pans then? Should not it repel the same way to these? Two skills exist to cover of teflon the surfaces of pans and frying pans.
The method of the sintetización, which is similar to the smelting. It is a question of raising the temperature of the teflon even more or less 400ºC and once done this, it is printed strongly on the surface that we are interested in. Nevertheless, it is necessary to say that when this one cools down, it can jump with the time and separate of the frying pan.
Nevertheless, another option is that of the "bombing". There is modified chemically the side of the teflon that we want to give to the frying pan, bombarding it with ions in an electrical field and in the gap, with which, we will manage to start or remove many atoms of fluorine of the part that we want to hook in the frying pan or pan, then this part can get hooked up since what towards that the teflon was repelling materials was – as we have said earlier - the fluorine about the molecules. Once eliminated or started these atoms, we can modify this face adding to him any other material that should favor the addition, as for example, the oxygen.
Since you see, this second option is the one that gives better results, what explains the motive for which one is the method most used to adhere the teflon to another type of materials.
Although it is much known by the recovering that we have just explained, the true thing is that the teflon is used in many other things: isolation of cables of communication of information, in clothes and hangings (to repel water and spots), in revetments of planes, rockets, spaceships, in prosthesis, in electronic components, paintings, etc.
Many of the squares that exist for our geography, especially in the south, are a typical example of square of white, with the paved margins, with arboreal vegetation in the flowerbeds that surround it, with banks alternated between them and with the typical corresponding flock of pigeons. Two examples of this type of squares are that of the Track in my people, Arahal or certain parts of the enormous Park of Maria Luisa in Seville (meet as the Park of the pigeons). Also there are of white the bullrings. White of the Square of the Track in Arahal (Seville) There are the people who thinks that for tradition it is necessary to support the squares of white, and to leave that the children play, get dirty and roll about in him, better that to have landscaped or paved squares, without thinking that a child can suppose the white one problemilla of health. Due to this and in the entry that I prepared for another blog in which I collaborate, I thought of making her extensive to the Museum of the Science, and here the result is after modifying it properly. The first thing will be to know something more on the white one, of which there is no a lot of information in the network, although it is always a little: The white one is a sedimentary material, of organic origin and of yellowish - orange color, which is obtained of a type of lime rock, the limestone nummulítica, that it comes from the remains of conches of nummulites, a type of protozoans foraminíferos, with a calcita conch, aragonito and rarely silica proceeding from the area of the Hills, in Seville, although also it is possible to find in the basin of the Yellow river in China. It might think that as it happens with some types of sand, rich in silica, the exhibition prolonged to the white one and his consistent respiration might provoke silicosis, a serious illness chronic and irreversible that affects professionals who work with this material, for example in the metalworker, ceramics, mining, marble, vídrio..., but on this part we can be calm, position on that, as I commented in the previous paragraph, the silica is an element that rarely appears in the white one or is in minimal quantities. But there is another problem and it is given by one of the biological elements of the squares: I refer to the pigeons, since there are a few birds that have turned into last decades in an urban plague in our villages and cities. In spite of his more or less agreeable appearance and his good reputation (pigeon of the peace, carrier pigeons, cartoon pigeons...) there are one more plague, how there can be the cockroaches, the rats or the termites. Apart from this it is not strange that bring over to the human beings any more of the account, since they have lost the fear of the persons and do not hesitate to steal meal or give pecks to the incautious walkers who approach to feed to the 'little doves'. And let's not say already, if they bombard you with his stinking depositions... Of course, with this I do not mean that the human beings we have any more rights that the rats, the cockroaches or the pigeons... are thought by me that, simply, we are species that we compete for the same space and resources... and because of hygiene, we say that it is not very suitable to share hearth with these animalcules... Pigeons in the Square of the Track in Arahal (Seville) The pigeons that they inhabit in our cities and squares belong to the species Columbia domestic livia, a subspecies proceeding from thedomesticated ferocious pigeons. The domestication was carried out by the man hundreds of years ago, but nowadays these live in the semiwild state, coexisting with us, perfectly adapted to the transformed urban environment. Before continuing, I would like making clear, that the problemillas about which I speak are not serious want to create unnecessary alarms, simply I try to inform about a small question that it appears with the union of these two elements about which we are speaking: white + pigeons. Pigeons in the Square of the Track in Arahal (Seville) The excrement of the pigeons is mixed little by little with the white one and there happens to be part of this one, since it is difficult to clean, without eliminating also the white one, which supposes that when dust gets up and this one stays in suspension in the ambience, it can go on to our lungs (both the sandy material, and the depositions of the pigeons). And to contact pigeons feces can represent a small risk for the health. Controversy exists with regard to the illnesses quantity that the pigeon can transmit the human beings, but more or less we can speak that approximately 30 infectious diseases exist from these birds to us, and approximately 10 transmissible ones to other domestic animals. In terms of public health, the zoonosis of major importance are criptococosis, aspergilosis, salmonelosis, listeriosis and estafilococosis, that they can be transmitted across the air or his feces. Another three a little stranger illnesses associated with the feces of the pigeons are: histoplasmosis, criptococosis and psittacosis: - The histoplasmosis is an illness caused by a mushroom that grows in the feces of the pigeons, which it can spend to our respiratory system, although only in cases of high exhibition it can cause infection. It is an illness that sometimes does not give symptoms and when it shows them there are the same symptoms as a flu, with what the people make a mistake. The persons inmunodeprimidas if they cover more risk of enduring the symptoms. And it is necessary to say that the illness one cannot transmit from person person. - The criptococosis is another illness for fungi associated with the feces of the pigeons, although also it is very little probable that the healthy persons turn out to be infected still at high exhibition levels, but, as in the previous case, there is an important infection risk for having the flagging immune system. - The psittacosis (also acquaintance like ornitosis or fever of the parrot) is a rare infectious illness produced by bacteria, which affects principally parrots, cockatoos and parakeets, but also it can affect to other birds, such as the pigeons. When the feces of these birds dry off and are transported by the air they can be inhaled by the persons and fall ill. In the human beings, this bacterial illness is characterized by fatigue, fever, headache, eruption, shakes and sometimes pneumonia. The symptoms appear approximately 10 days after the exhibition and his treatment consists simply a common antibiotic. The persons with major contagion risk are birds proprietors, personnel of shops of pets, veterinary, and you present yourself with the systems immune debilitated. My small Marten chasing to the pigeons in a square of white In spite of all this, I am the first one that I will keep on taking to my kidling to the square of the Track, or to the Park of the pigeons to which it runs and plays with other children, and I will sit down myself there to accompany it, but I will try that it gets dirty, touches or breathes the minimal quantity of white possibly, while they keep on standing out to his wide ones over there, the nice and adorable pigeons... Marten with the pigeons to the fund. --------------------- Source of the images: - The Science of the Life. --------------------- It notices: This entry is a version lightly modified of the one that I published in The Arahal blog and it has been checked, nicely, by Sohpie. --------------------- Sources: - Wikipedia. - Educared. - News Educared. - NYC Health. - Fueraplagas. - Scielo. - Environmental engineer. - Croquettes rain. - The Arahal blog.
The sensor CCD has turned into one of our inseparable technological partners. It is possible that many you do not even know what is, not why it works, but almost with entire safety you use it or have used it in some electronic device. Do not you imagine where? Without going further in your mobile phones with camera or in a digital camera. Any electronic device that receives photo or video uses almost with entire safety a sensor CCD. Now then: how does a sensor CCD work? The basic functioning is not too complicated to understand and it is based on the photoelectric effect. This effect was described of theoretical form by Einstein in the year 1905 (receiving later the Nobel Prize in 1921) and it comes to us to say that when a photon (light) affects on a surface, if it has enough energy, it is going to manage to start some electrons of the material. With this it is possible to generate a usable electric current for what it is needed. Knowing this, we can already begin treating the sensor. As we said already in the previous paragraph, the sensor CCD works basically for the photoelectric effect. Therefore, after the light makes affect on him there are started electrons that finish in a condenser. To major intensity of the light more electrons are started and therefore major is the stored load. Depending on this load it goes to have a different voltage that will be what determines finally the color. This happens for every cell of the sensor, or what is known generally as a pixel. If we join quite these cells or pixels it is when we have the captured image, which then we will be able to see in the computer or in any other device. When it is said that a digital camera has a number of pixels it means that the sensor CCD has this number of cells and therefore, major resolution is going to have the image to major number of cells. The cells of the sensor CCD are ready in rectangular form, hence the digital photos have this form. To finish, I want to propose a small exercise to you. It is sure that you have listened more than once that a digital camera has 5 Mpx (5 million pixels), or even more. Now then: have you ever stopped to calculate the number of pixels (resolution) that has your screen of the computer? You can do it very easily multiplying the pixels breadth by the high place, that is to say: 1280x800, 1440x900, or the resolution that you have. The result is surprising: truth? Greetings ;) Source of the images: Wikipedia (1) and (2)
Healthtalkonline is a curious page. In her you can listen to the history, experience and persons' opinion that have endured an illness. In contrast to other Internet pages where the persons write his history without much ado, in Healthtalkonline the persons are interviewed by investigators of the Oxford University. With his histories, other patients, relatives, minders and professionals of the health they can benefit a lot of his experience on having been able to come closer the illness from a more personal point of view, knowing how it is lived, the impact in the daily life, how they usually confront it affected in his daily life, etc. On the page it can think of everything, from the cancer up to the disabilities or how one lives the traumatic death of a dear being.
I find many positive points to him to this page. A simple design, every section of a color, very well structured. For example, if we go away to the section of bones and joints, we can get into the subsection of rheumatoid arthritis, where in turn we can go straight to what is this illness, the impact that he supposes that they diagnose it to you, the image that there has the proper patient of himself, what therapies are to choose, how it is every day with arthritis.
I do not know any page in Spanish like this one. A sorrow, it would be very interesting to have a web like that for the Spanish-speaking ones.
When a small child asks you where from the babies come, you remain a bit flabbergasted thinking how you are going to explain it to him. And when he feels like asking why the mom of Fulanito, who is diabetic, has had a child taaaan big, you arch an eyebrow again and wonder also why. Let's revise little physiology of the pregnancy. On having remained a pregnant woman, a few "infrastructures" form to support the comfortable, warm baby and good fed inside the womb. One of the main frames for all this is the afterbirth, across which a lot of nutrients come to him. They not all come to him from the same way and there are some of them that do not come to him, like the insulin, which prepares the fetus for itself. A diabetic woman does not have proper insulin production or this one is very scarce, so that when it consumes carbohydrates and sugar is not taken of rapid form not effectively to the cells and the "larders" of these elements in the organism, for example the liver. To this it is necessary to add him that during the first trimester of the pregnancy the body of the gestante is regulated in such a way that there is more glucose in blood, which spreads across the afterbirth up to the fetus and is one of his basic sustenances. The fetus prepares insulin as the quantity of glucose that is coming to him. And where do you take us with all this glucose roll for above, for below, insulin of the mother, of the child and etc? Since to that the insulin has other functions apart from that to facilitate the storage of the glucose. It facilitates the synthesis and the proteins deposit, working together with the hormone of the growth to stimulate the growth (cost the redundancy), being the insulin the principal hormone in charge of the increase of size and weight of the baby. This way we meet a diabetic woman with a better or worse control of his glycemia and a fetus that not of to produce insulin because it is receiving enough glucose, putting itself really hermosote. Another day we speak about the test of O'Sullivan that is done to the pregnant women to discard the diabetes gestacional :)
We turn to the section How it works... to speak about the functioning of the television. The silly box, since they name it some, takes with us about 50 years, but his first steps happened it does more than 100. From these first steps with the Nipkow disc until our days with the sophisticated screens SMELL there has been a long trip, and obviously we are not going to speak about all the contributions that the science has done to improve the television, but yes that we are going to treat two models: the television CRT and the television of plasma. 
You can see it to
His history is well curious: Roy J. Plunkett (right in the image) and his assistant Jack Rebok (left in the image) they realized experiments for the company DuPont somewhere near the year 1938. In one of them, they wanted to obtain major quantities of tetraflouretileno (TFE). This material, after a simple treatment, was vaporizado and it was happening across a few pipes and meters of flow, later to finish in a camera where other chemicals were applied to him so that it was reacting. As in many other inventions of the history, the find was fortuitous. They detected an error in the system and the motive was not explained. On having dismantled some valves, they realized that there was a white substance in the shape of dust. The TFE there was polimerizado. They tried with many acids and dissolvers, but they did not achieve that it was affecting to this polymer. Then, the history we already know it. The DuPont was interested and happened to be part of his scale of polymers. 
White of the Square of the Track in Arahal (Seville) 
Pigeons in the Square of the Track in Arahal (Seville) 
My small Marten chasing to the pigeons in a square of white 
Marten with the pigeons to the fund. 
The sensor CCD has turned into one of our inseparable technological partners. It is possible that many you do not even know what is, not why it works, but almost with entire safety you use it or have used it in some electronic device. Do not you imagine where? Without going further in your mobile phones with camera or in a digital camera. Any electronic device that receives photo or video uses almost with entire safety a sensor CCD. Now then: how does a
