Popular science article: Dracaena opens.
The night is full of autumn flowers with dew, full moon tower, Yu Yan Bridge, fragrant dust and Wan Li live in sorrow.
How long is this life expected? The giant trees are boundless, slim and graceful, and the dragon blood is fragrant and fascinating.
The dragon blood trees (fragrans, meaning incense) in the Dragon Blood Tree Garden of Xishuangbanna Tropical Botanical Garden are blooming in large numbers, and the fragrance is refreshing, especially at night.
Dracaena stenophylla, also known as Brazilian wood, is a kind of Dracaena of Asparagaceae. This is a flowering plant native to Africa. It grows on the plateau at an altitude of 600-2250 meters, reaching Sudan in the north, Mozambique in the south, C? te d 'Ivoire in the west and Angola in the southwest.
Brazilian wood is a famous new tree, with neat and beautiful plant shape, wide leaves, luster and green. Replace indoor foliage plants. Small and medium pots can be used to decorate the study, living room and bedroom, which looks elegant and chic; Large and medium-sized plants are arranged in halls, conference rooms, offices and other places, which can be enjoyed for a long time and are quite exotic; Especially the Brazilian wood planted at random, with clear branches and leaves, can it be given to people? Step by step? The moral of.
Brazilian wood is an evergreen tree, which can be as high as 6 meters in its place of origin, and the height of potted plants is generally 50- 100cm. Its trunk is upright and sometimes branched. Leaves clustered at the top of the stem, oblong-lanceolate, petiole-free; The leaves are 40-90cm long and 6- 10cm wide, curved into an arch, with wavy edges and slightly blunt tips; Bright green, shiny. Spikes, small flowers, yellow-green, fragrant.
Brazilian wood is not produced in Brazil, but in Africa, and has been widely introduced and cultivated in China in recent years. Brazilian wood is propagated mainly by cutting. After years of cultivation, if the plant is too high or the leaves at the lower part of the stem fall off and the plant shape is poor, it can be pruned, and the cut branches can be used as cutting materials.
Popular science article: excavation of paleontological fossils
In the eyes of paleontologists, bone fossils scattered in loess are not just a pile of dead things, they are like scattered puzzles, pieced together, maybe a flying dinosaur, or a huge whale, or just a primitive skull, or a bug at the origin of life. But biologists are not picky. How do they know where there are fossils? Are there any instruments that can detect underground fossils? How do they know the names of these creatures?
find
Paleontology is an ancient and traditional basic science, which studies the fossils of organisms that have appeared on the earth, so as to understand the origin, evolution, extinction, recovery and its relationship with the environment at that time in geological history. Generally, it goes through several stages, such as field investigation, fossil excavation, specimen restoration, scientific research, morphological restoration and museum display.
Before on-the-spot investigation, we should first choose areas and strata. For example, if we study pterosaurs and dinosaurs, we should look for fossil clues in Mesozoic strata. Mesozoic includes Triassic, Jurassic and Cretaceous, while reptiles such as pterosaurs and dinosaurs only lived in Mesozoic, so their fossils could not be found in the sediments of late Cenozoic and early Paleozoic.
In the wild, we should not only find, verify and determine the location of fossils recorded in geological documents, but also visit local villagers to investigate whether fossils have been found in this area and when. On this basis, look for possible fossils. Therefore, looking for clues of wild fossils and determining the excavation site do not depend on any advanced instruments and equipment.
Determining the best excavation site is mainly based on the number of fossils exposed on the surface and the rock stratum where the fossils are buried, to analyze and judge whether the fossils of this rock stratum are complete or relatively complete individuals buried in situ, scattered bones buried in different places after being transported, enriched burial caused by group death, or a small amount of burial caused by normal death. For example, the Jehol biota in western Liaoning is different from the dinosaur biota in Laiyang, Shandong. The former is gray-black shale, which means that they were formed in the reducing environment of deep lake and still water. In this environment, the fossils in shale are generally complete individuals, and judging from the large number of volcanic ash interlayers appearing on the profile, volcanic activity here is very frequent, and the death of these creatures should be related to the catastrophic events caused by volcanic eruption. In other words, they died in an abnormal cluster. As long as the horizon and position of fossil outcrop are found, it means that relatively rich and complete fossils are buried. So as long as we find an outcrop with only one bone, we can determine this position as the best exploration site without hesitation. The latter is buried in sandstone and mudstone formed by alluvial rivers, and it is purple gravel sandstone and mudstone piled up in disorder, belonging to the sedimentary type formed by debris flow in oxidation environment. Most fossils in this kind of sediments are scattered and preserved, and the best fossil position should be the point with the most outcrops in the same horizon. The more outcrops, the richer the fossils.
collect
It is important to find fossils in the wild, but it is more important to collect them intact. According to the lithology and burial environment of the strata where fossils are located, different collection methods can be adopted, such as box-fixing method, gypsum bag and? Sandwich biscuit method and so on.
Large dinosaur bones and other fossils scattered in river alluvial burial environment, such as Laiyang dinosaur fauna in Shandong Province, are mostly collected by gypsum bags. In this method, the periphery of fossils and surrounding rocks is slotted downward, and when it exceeds fossils, it shrinks inward to make it mushroom-shaped. Pour gypsum on it, cover it with sacks, flatten it, then pour thicker gypsum, smooth it and compact it, and add wood or wooden sticks. After the gypsum is heated and hardened, it is smashed into the steel drill and separated from the rock stratum and turned over, and registered by unified number.
It is necessary to adopt a complete fossil skeleton buried in Hunan shale similar to the West Lake in Liaoning Province. Sandwich biscuit method. Because there are many cracks in the shale containing Jehol biota fossils in western Liaoning, and all of them contain volcanic ash, the rock stratum is very soft after long-term immersion in groundwater, and the volcanic ash will be dehydrated quickly after collection, resulting in rock stratum deformation and powder crushing. Therefore, the collection of such specimens has always been a difficult problem. But with what? The sandwich biscuit method can collect more than ten specimens a day, and the fossils are not damaged at all. This method needs to determine the scope of a single fossil, cut notches and small grooves on the rocks around the fossil with a knife, pad soft paper around the specimen along the grooves, tightly wrap and fix it with transparent tape, separate the relatively brittle layer under the fossil layer, translate the specimen along the layer to the prepared wooden board, then pad the soft paper, press another wooden board, wrap it with adhesive tape, and finally slowly dehydrate and dry it in the shade.
Fossil restoration is one of the most critical links in paleontology research. Fossil restoration is to expose fossil bones as much as possible without damaging fossils. What if it's being repaired? When collecting fossils by sandwich biscuit method, the completely dry specimens should be opened in front, and the exposed bones should be repaired in turn from the upper surface of the bones found in the field. Some specimens also preserved the feathers of dinosaurs or birds, pterodactyl wing membranes and other soft tissue structures, so they should be carefully repaired under a microscope, and even X-ray scanning can be used to confirm the distribution of bones to guide the repair.
For the fossils collected by gypsum bags, it is necessary to determine the size of the fossils and collect them by slotting, and most of the fossil bones in the upper layer have been exposed. Only by starting from the lower layer will the restoration progress be accelerated. In the process of repair, the anhydrite around the gypsum bag should be sawed off with a saw blade to expose the surrounding rock, and then cleaned down in turn until all the surrounding rock around the bone is cleaned up. In the process of cleaning, the naturally fractured bones in the rock stratum should be reinforced with glue at any time.
name
The most basic research method of paleontology is the detailed description of fossil morphology. Although many of them are qualitative descriptions, they are the basis of all other studies. Based on the traditional morphological description and taxonomic study, this paper analyzes the phylogenetic position of this biological type and discusses its origin and evolution. With the emergence of new technologies and methods, many new technologies are gradually applied to the field of paleontology, such as high-precision CT scanning and three-dimensional reconstruction technology, which can clearly understand some internal morphological structures of fossil organisms, such as complex brain and skull systems, without destroying fossils. The application of electron microscope and slicing technology can observe the microstructure of fossil bones and understand the age and individual development of organisms.
If fossil research proves to be a new species that has never been discovered, paleontologists will name the fossils. The naming of ancient creatures also adopts binomial method, such as Avatar, the Ikarosaurus. In Latin names, the front is the generic name, followed by the species name, and all the generic and species names are italicized. Translate it into Chinese. What's its name? Avatar? Before the name? Icarus pterodactyl? Finally, the common name can be used alone, and we can call it? Icarus pterodactyl? , but the name can't be used alone, and it must be used together with the common name. There are several etymologies of paleontological naming, including: the names of fossil producing areas, such as Hami pterosaur in Tianshan Mountain; Names, that is, to commemorate some historical figures, scientists who have made important contributions or discoverers of fossils, such as sage Confucius; Fossil features, such as pungent Qingdao dragon, are named after long dinosaur heads. A prickly nose? . Among these names, the genus name is unique, and the species name can be named repeatedly.
Through the study of fossil morphology, we know the size of individuals, the shapes of skulls and teeth, the size ratio of bones in the body, and even the shapes of soft tissues such as feathers, as well as their living environment. Can artists use it? Could this be ancient? According to some biological characteristics and similar environmental background, the morphological recovery map and ecological recovery map of fossil organisms are drawn.
Popular science article: housework may save your life.
I have never been keen on physical exercise. My working state is basically sitting in front of the computer for a few hours every day, chatting with others occasionally, and of course sitting. In the evening, I usually sit and watch TV. Unless I go out, I usually take a taxi first and then sit and eat. Sitting is my normal state. I may sit 15 or 16 hours a day (and lie down and sleep for the other 8 hours). All the research evidence shows that low-level physical activity is not good for health. A few years ago, the famous medical magazine The Lancet published a series of commentary articles, pointing out that low-level physical activity is the fourth biggest killer of human health today. According to the data of the World Health Organization,10% (5 million people) of the people who die directly every year in the world come from low level of physical activity.
My problem is that I know the harm of inactivity, but I can't motivate myself to stand up and exercise. If I really want to do sports, I need another reason besides being good for my health. It's not that I have physical defects and can't exercise normally, but that I have psychological resistance to it. For example, when my son was in Beijing, I got up an hour early every morning and rode 5 kilometers to school with him. I will have a cup of coffee in the cafe near his school, then go home by bike for 5 kilometers, and then go to the office only 500 meters away from my residence. Obviously, cycling is my sport, because it is also done by sitting! But this is a sport. Moreover, riding with a boy of 17 years old is quite fast. On the way, we often try to compete with electric bicycles, and my heart rate is likely to reach the level of physical training.
The point here is that there is another reason why I ride a bike happily every morning, that is, to be with my son. We often go against the wind, and sometimes we encounter snowstorms, and we don't talk much. But many times, he will tell me what he did at school, his plans for the future, and various meaningless male topics, such as Ferrari 458 Italy (Ita 1ia) or Lamborghini Aventador, which is better? In fact, we can't have both, but it's very important for men to understand this problem (by the way, Lamborghini Ivando is better). In the last three months in Beijing, he transferred to another school, which is17km away from our residence. However, I still go to school by bike with him. We got up 30 minutes earlier than before. There is no cafe near the new school. Every day as soon as he enters the school gate, I turn around and walk back.
In those months, when I went to work every day, I almost finished riding the whole marathon. However, for me, it has nothing to do with sports. My son is now back in England to go to college. I still ride my bike every day, but only from my residence to the office. The total amount of exercise every day is only 10 minutes, and my speed and heart rate are not much better than when I am sitting and working. I never thought that I would turn around, ride for half an hour at three times the usual speed, exercise until I sweat and come back. My son is not around, so cycling is just a sport for me and I don't have enough motivation to do it. I know all kinds of statistical results and biological principles about low physical activity, and I also know the benefits of exercise and fitness, but this inertia is still so strong. So what will happen to people who don't understand the benefits of sports?
However, how healthy outdoor sports are for people living in Beijing is another question. This problem is air pollution. As we all know, the air quality in Beijing is very poor. I used to ride a marathon every day for three months. Is it really good for your health? Considering the air quality when riding, the answer may be no.
So there seems to be nothing left. If you don't exercise, you will encounter various physical and health problems related to low physical activity level. But if you exercise, the air quality in most parts of East China may make exercise more dangerous than not exercising. So what exactly should we do? At least for men in China, the answer is housework. This answer must be very pleasant for most women in China. Does your husband never share housework at home? It may be worth pointing out to them that doing more housework can reduce their risk of various non-communicable diseases, including cancer.
The evidence of this assertion comes from the publication of Public Library of Science 20 13. In an article in PLOS Family magazine, researchers studied the benefits of housework to 4,000 middle-aged and elderly people in China. In the screening process, 1 133 subjects with heart disease, stroke, cancer or diabetes were excluded, and the final valid data came from 2867 healthy individuals. They recorded the subjects' daily physical activities, including leisure activities, such as exercise and walking, gardening and mowing the lawn. In addition, the researchers also recorded the time the subjects spent on indoor housework and home maintenance. After that, the researchers followed the subjects for 1 1 year, during which 452 people died, of which 185 died of cancer. After revising the data according to age, education level and lifestyle, they found that the death risk of individuals who do more and heavier housework is significantly lower than that of individuals who rarely or never do housework. The risk ratio of the two is 0.72, which means that the risk is reduced by about 30%. This influence is enormous. However, in addition to the direct impact of housework, there may be many reasons for the reduction of disease risk. For example, people who do more indoor housework may have more sports or outdoor leisure activities. Perhaps people who don't do housework at all are actually seriously obese, so their mortality rate is related to obesity, not to the amount of housework. However, the risk ratio between body composition (body mass index) and living conditions (married, unmarried, etc.). ) and outdoor leisure activities are only 0.7 1, indicating that the above other factors have no effect on the relationship between housework and all-cause death. Housework has a more significant impact on cancer risk. Subjects who do a lot of housework have only half the risk of cancer (hazard ratio is 0.52). However, engaging in moderate and light intensity housework has little impact on the risk of death.
Two findings in this study are particularly surprising. One is that the influence of housework far exceeds leisure activities including sports. Secondly, the significant impact of housework on health is only seen in men. For the women surveyed in the study, the amount of housework is not related to all deaths caused by death or cancer! Therefore, the results of this study are really good news for women. You can leave all the housework to your husband without worrying about increasing the risk of death or cancer; Your husband does all housework, so he can live longer. In my opinion, there are two additional benefits. Compared with physical exercise, the purpose of doing housework is different. In fact, it is a job. Compared with simple exercise, I am more likely to insist on doing housework, just like I can take my son to school by bike, but I don't want to ride without him for a while. Another advantage is that, by definition, housework is done indoors, so this is something you don't need to expose yourself to air pollution in Beijing? Exercise? .
This sounds too good to be true. This may not be true. For all these studies, it is very important to remember that although the sample size is very large (nearly 3O00 people) and the follow-up period is very long (about 10 years), the results obtained are only a correlation. There is no necessary causal relationship between the increase of housework and the decrease of mortality, no matter how convincing the data seem, no matter how consistent they are with other research results. For example, a person's commitment to housework is likely to reflect his overall positive attitude towards life. If a person keeps his home in good order, it may mean that he is also active and serious about other things. Perhaps their overall attitude towards life has influenced other things they do, thus reducing the risk of death. These people may eat healthier, have a wider circle of friends and be more enthusiastic about community activities. All the above points are considered to be related to longevity and the risk of non-communicable diseases including cancer. Housekeeping may be just an indicator of other factors that really affect the risk of death. So, if you decide to take on a lot of housework, but don't make any changes in other related things, the end result may just be that you have a cleaner home. The impact of housework on the risk of death will be weak, and may even be negative. Maybe people who are willing to do housework and housework maintenance have a special set of skills, but those who don't do housework don't. If you suddenly start to do all kinds of housework without corresponding experience, you may face higher accident risks, such as falling off a ladder and getting an electric shock. In fact, if your view of things is quite negative, suddenly taking on a lot of housework every week will not make your view of life more optimistic, but it is likely to make things worse. What we really need is a randomized controlled experiment, in which the subjects are randomly divided into two groups, one group is given more housework and the other group is not, and then their death risk is followed up. Only in this way can we determine whether the correlation in observation and research belongs to causality.