We know that the earth was attacked by asteroids and comets in its history. We just have to remember the sad ending of the dinosaurs. However, even if there were many asteroids and comets falling on earth, it is hard to study them. Erosion and geological changes like volcanos and water makes it hard to identify the craters and to study its age. Much better are the circumstances on the moon. There is no water and no volcanos. Therefore, the craters stay “untouched”. And when there would be a time in which many asteroids and comets attacked the moon, it just seems logical to assume that in the same time there were also asteroids and comets falling on earth as they are close neighbours. Therefore, knowing the history of the crater impacts of the moon also reveals some informations about the history of our earth. Interestingly, lunar probes collected by Apollo astronauts showed that around 3.9 billion years ago the crust of the moon was so hot that all rocks in it metamorphosed. This was the birth of the lunar cataclysm hypothesis: the heating up of the crust may be created by a large number of asteroid and/or cometary collisions in a brief pulse of time. However, did the lunar cataclysm really happen? The Apollo astronauts just collected probes in a small area so just because these probes are from the same age, it has not to be valid for the whole moon surface. However, in December 2000, Cohen et al. published a study which results support the hypothesis. They studied the ages of 4 lunar meteorites which were found on earth. The lunar meteorites are like random samples from the moon surface and indeed the scientists found in them nothing which was older than 3.9 billion years. So that supports the hypothesis that at this time point many collision events happened on the moon. And maybe this also affected our earth. Remembering that the earliest isotopic evidence Scientists are now wondering if this cataclysmic bombardment may have affected life on Earth or been involved in life's origins. The earliest isotopic evidence of life is ~3.8 billion years old. Can this be an accident? (please read here more about it: http://www.lpi.usra.edu/exploration/science/lunarCat/ ) "Support for the lunar cataclysm hypothesis from lunar meteorite impact melt ages."
B. A. Cohen, T. D. Swindle, and D. A. Kring. Science 290.5497 (2000): 1754-1756.
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In my opinion, science is the ability to ask questions which either can't be answered or which answers just raise new questions. The paper today is from the first kind. It asks "are gorillas right-handed or not?" and the result is: We don't know. In 1992, there were just 22 published studies about hand preferences in gorillas. Although, McGrew and Marchant analyzed and compared the study results, the number of studies was not enough to conclude if gorillas are left-, right- or ambi-preferent. Therefore, based on the knowledge from 1992, I can not answer you the question. But today... in the time where everybody can access the world-wide knowledge everytime with his smartphone, laptop or tablet... today it is different, isn't it? So many people had now so much time to observe gorillas and to share their observations with the rest of the world. So today we have to know the answer, right? No. Unfortunately wrong. You still find contradictory answers to this simple question. Some webpages claim gorillas to be right-handed (http://phys.org/news/2012-10-predominance-right-handed-uniquely-human-trait.html) and some others claim them to be ambi-prefered (http://scienceblogs.com/developingintelligence/2007/10/16/why-animals-dont-show-handedne/). So if you always asked yourself: is there any question which science can not answer?... here you have an example :-D "Are gorillas right-handed or not?"
W. C. McGrew and L. F. Marchant Human Evolution 8.1 (1993): 17-23. Mathematicians like to claim that math is in everything. I won’t start a discussion about if this is true. However, what I can tell you is that math is in origami. I am sure you all know the art of folding paper in creative shapes. Also it is an ancient Japanese art, it is a quite “young” hobby for the rest of the world. “Modern origami, in the sense of what one finds when looking at a typical origami instruction book, only dates back to the 1940s and 1950s.” Since then, a lot of progress has been made in this field. While in the 1970s the people thought, "It is impossible to make a grasshopper using one sheet of square paper”, we know know: it is possible. And we know: origami is not only free creative art, it also follows some certain rules. This is were the mathematicians entered the field. With increasing complexity of the origami figures, finding a way to fold them became more and more complicated. In the 1990s, “Fumiaki Kawahata, Toshiyuki Meguro, and Jun Maekawa in Japan and Robert Lang in the United States independently discovered a connection between origami design and circle-packing.” Every “peak” in a origami figure,… a leg/antenna/tooth/… needs to be made from a circle on the square paper. These circles can be on the border of the squared paper or in the middle of it. I can not explain why it has to be a circle. Let us believe that. Then I can tell you, that this way of thinking of “figure extensions” as circles is the base of the popular tree algorithm for designing folding schemes for origami figures. Every part of the planned figure becomes a point in a network scheme with lines (edges) between the points which correspond to the size relation of the later formed body part. This map is then projected to the squared paper by drawing for every point a circle with a radius corresponding to the edge length. The problem is to find a way to “arrange the circles, making them reasonably large and, for convenience, positioning them along axes of symmetry of the square, if possible.” The rest is “quite” easy: “connect some of the centers of neighboring circles with creases to begin an outline of the crease pattern.“ Of course there are now conputer programs for this (http://www.langorigami.com/article/treemaker please look here also for pictures as a visual support for my description). But fact is, this algorithm, based on mathematical rules, helps forming new origami figures and this is why math is in origami (as claimed in the beginning of this text). "Origami design secrets: mathematical methods for an ancient art."
Robert J. Lang and Thomas C. Hull The Mathematical Intelligencer 27.2 (2005): 92-95. In many countries, the usage of mobile phones while driving is forbidden. The prohibition is based on the non-use of one hand which can cause interference with the trained driving movements and not on the distraction due to the phone conversation. Therefore, hands-free phone kits are still allowed. But how much does a hands-free phone conversation distract the driver compared to listening to the radio or talking with a passenger? Collet et al. (2009) compared reaction time and heart rate at different secondary tasks while driving. While listening to the radio didn’t affected the reaction time, the reaction time while hands-free phoning and in-vehicle conversation was 20% longer compared to driving without any distractions. That means, referring to the reaction time, there is no difference between phoning and talking to a passenger. Also the mean heart rate, which gives a clue about the strain of the driver, was the same for talking and phoning. Both secondary tasks seem to stress the driver much more than listening to the radio. So what can we learn from that? If you want to concentrate while driving: shut up. Don’t talk to anybody. Turn on your radio instead. "Physiological and behavioural changes associated to
the management of secondary tasks while driving." C. Collet, et al. Applied ergonomics 40.6 (2009): 1041-1046. Lithium-ion batteries are everywhere: in your smartphone, in your camera, … These types of rechargeable batteries are great for any portable electronics as it has a small memory effect and low self-discharge. However, that doesn’t mean that it can’t be improved. In 2007, Fu et al. tested three-dimensionally ordered mesoporous titania microparticles as “new” anode material. Why titania? I don’t know. Fact is, “conventional Li-storage materials suffer serious capacity loss when they are charged/discharged at a high rate. Polarization caused by slow diffusion of lithium ions and electrons in active materials is one challenging problem.“ As far as I understand it (and please my dear reader correct me if I am wrong) that means, that the lithium ions need a certain time to travel between between the electrodes. Therefore, if you are charging and discharging faster than the lithium ions need to travel from the one electrode to the other, this results in a capacity loss. Normally the anode in a lithium ion battery is made of graphitic layers. Between the stacked layers the lithium ions are normally stored in the charging process. While discharging, the lithium ions travel to the cathode. So summing up, the traveling time between the anode and the cathode (and the other way around) is the reason for polarization. However, “previous studies showed that electrode materials with three-dimensionally (3D) ordered mesoporous structure could decrease the polarization and enhance the performance at high rates”. That means that if the electrode material has a 3d structure with “pores” instead of the graphitic layers, the lithium ions can travel faster and so the polarization is decreased. Therefore, Fu et al. created a 3D ordered mesoporous structure out of titania and used it as anode. Indeed, the 3d structure was “beneficial to the diffusion of lithium ions” which reduced the capacity loss. So 3d is better than 2d… at least regarding the structure of the anode material in lithium ion batteries… (for movies I still prefer 2d… but this is maybe a question of taste). "Preparation and characterization of three-dimensionally ordered mesoporous titania microparticles as anode material for lithium ion battery."
Fu et al. Electrochemistry Communications 9.8 (2007): 2140-2144. |
IdeaI love to increase my general science knowledge by reading papers from different fields of science. Here I share some of them. Archiv
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