I learned in school that in the 14. century the “Black Death” plague was caused by the bacterium Yersinia pestis which was transmitted by rat fleas. However, this may not be true. So yes, plague is caused by Yersinia pestis, but there are different infection ways: (I) from rat fleas to human, (II) from human ectoparasites (fleas and lice) to human and (III) from human to human by inhalation from infected droplets. But how you can find out many centuries later which infection way was the basis for the “Black Death”? The answer is: with mathematical models! Katharine R. Dean, et al. (PNAS 2018) created mathematical models for all three infection ways. So they were able to simulate how infection rates would develop over time for each type of infection. Then they fitted the simulation results to real outbreak data and showed that in many cases the “human ectoparasites to human” model fits best. Of course, it can still be that it was a mixture of different infection ways and that the main infection way differed from region to region. Nevertheless, it shows that the story which we learn in school, that the plague is caused by infected rats and rat fleas, is maybe too easy.
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We all know that kind of guessing games: How many candies are in this jar? Which weight has this cow? The question is how you can improve your guess and maybe win the prize. In 1906, Sir Francis Galton noticed that the aggregate judgement of the players, the average of their estimates, closely approximated the true value. This is called the wisdom of crowds. So of course, a good method to win is to form a small group, take the average of the estimates, and share the win in the end. But what to do if you don't want to share? One possibility is that you ask yourself multiple times and take the average of your guesses. This is called the wisdom of the inner crowd. That works best if you let some time pass between the guesses or if your short-term memory is not the best and you tend to forget fast what you guessed before. Unfortunately, there is still a large chance that you will be beaten by any 2-person team. As the paper of Dennie van Dolder and Martijn van den Assem (2017) points out: "The average of a large number of judgements from the same person is barely better than the average of two judgements from different people". So the message of the day: Ask the others and learn to share! The magic of a break. For a short time put your work aside and do something else. At least while struggling with verbal learning tasks, such breaks should be helpful and improve your memory. The “spacing effect” as it is called in memory literature, refers to the fact that spatial learning (with temporal lags between the learning session) results in greater retention accuracy and less forgetting compared to massed learning (no lags). There are many different theories why “spatial learning” works. Maybe it works because that the cues which are present in the different learning session variate (a different environment, a different mood) and improve learning. And/or it is just this cycle between forgetting (in the lags) and recall (during the session) which strength the memory. Whatever it is: does it work for any type of learning? Most experiments focus on verbal learning. For motor learning the studies show variating results. Melody Wiseheart (great name by the way) and colleagues analysed if there is a spacing effect while learning to play the piano. They asked students with varying music education to perform two tasks: One focuses on the “translation” from music sheets to the right finger movement on the piano keyboard, the other on the auditory feedback to reproduce a certain melody with right volume and rhythm. Interestingly, massed learning and spatial learning strategy showed both the same learning performance in both tests. Maybe the time lags (max 15min) were to short. But at least it shows, that the spacing effect may vary with the learning task. “Lack of spacing effects during piano learning”
Wiseheart M, D’Souza AA, Chae J (2017) PLoS ONE 12(8): e0182986. Who else loves the TV-Show Bones? I am a big fan of this TV series. So no wonder that I liked the paper of Stian Suppersberger Hamre et al. (PLOS One, July, 2017). Like "Bones" they used human bones to reconstract the life-story of the individual. The only difference to the TV show is that they don't do this in order to catch a murder. Stian Suppersberger Hamre et al. do this for Sience. They analysed the skeletons of three individuals who lived in Trondheim (Norway) during the 13th century. They used different methods (skeletal examinations, genetic and stable oxygen isotope analyses) to analyse where and when they may were born, when they moved to Trondheim, how they looked like and if they had any illnesses. The result is a really interesting paper with three life-stories which show the variety of Trondheim citizens in the 13th century. They all had different birth places... one maybe even came from the Alps in Germany. They all died "young" in their 20s-30s. One even had a head surgery and survived it, which was not so common at this time. Great paper... a little bit like a story book! "Three individuals, three stories, three burials from medieval Trondheim, Norway."
Stian Suppersberger Hamre, et al. PLoS One 12.7 (2017): e0180277. Medieval music: when I read that word, immediately I hear lutes, pipes and drums in my head and pictures of singing bards, dancing noblewomen and royal parties are popping up. But how was this music perceived by the medieval people? Sensual or intellectual? The enthusiasm of humans to music is old. Already Aristotle considered music as one of the four diciplines (grammar, drawing, gymnastics and music) which was worth to spend free time in. The purpose of music was always the same: providing pleasure (hedone — delectatio). “Delectation that accompanies leisure is understood as the antithesis of sadness caused by work.” Work? What has work to do with music? Does it refer to playing music instead of listening to it? No. It is the other way around.“Play [music] should be a remedy for sadness and should provide pleasure in periods of leisure and recreation. On the other hand, the purpose of deductio (listening) is to give rise to noble and worthy thought as well as speculation or contemplation of things divine.” So listening to music is sort of intellectual work which can result in pleasure (delectatio). The base of this “listening is mental work” idea, is the Pythagorean tradition, which was a “major force in medieval music theory — the relationship between sounds can be expressed numerically, it may therefore be considered in terms of the relationship of two numbers, apart from actual sound and beyond physical time.” Therefore, besides the sensual level, there is also an intellectual level of music. And this is why the medieval philosopher “Peter of Auvergne considered deductio (listening) an intellectual activity dictated by the mind that led through delectatio (pleasure) to happiness”. But of course that doesn’t mean, that medieval people were all mind working people which couldn’t enjoy music just by listening, as the most of us are doing it normally. Also in the medieval times, according to Peter von Auvergne, there were two categories of listeners: “in the first category are free and educated persons prepared for intellectual pursuits, while the second category included uneducated and hard working persons who in moments of ease derive pleasure from games and spectacles”. Referring to the fact how I use music in my free time, I definitely belong to the second category. What about you? "The Medieval Concept of Music Perception. Hearing, Calculating and Contemplating."
Elzbieta Witkowska-Zaremba Scripta Instituti Donneriani Aboensis16 (2014): 369-376. The todays paper of the day is about stuttering. When I googled stuttering I found a funny quote: “Stuttering is Ok. Because what I say is worth repeating”. This quote highlights already the most prominent feature of stuttering: the involuntary repetitions of sounds and words which disturb the fluency of speech. Moreover, involuntary prolongations of sounds and involuntary silent pauses in which the person is unable to say anything, are also characteristics of stuttering. Sometimes people stutter in uncomfortable stressful situations, sometimes the stuttering is a persistant disease (also called chronic perseverative stuttering - CPS). The latter is the focus of the paper of Jolanta Góral-Półrola et al. (2015). The neurodevelopmental hypothesis of fluency of speech “suggests that the main symptoms in stuttering disorders are the result of integrated genetic, developmental, neurological, and social factors.” Based on this hypothesis, Góral-Półrola et al. (2015) looked at the gene expression of a 26 years old CPS patient. The focus was on stress related genes. Interestingly, “the expression of almost all tested genes, with the exception of IL1, in patient’s leukocytes were lower than in the control group.” This either means a lower stress load of this patient or insufficient stress response and protection of the cells. Of course, a single patient is not enough for significant study results, but having in mind that the most of us were already in a stressfull situation in which they started stutering, it seems quite logical that chronic stuttering may be connected to an decreased stress tolerance due to low stress gene expression. Just as remark: "Changes in gene expression associated with cell stress in the patient with chronic persevarative stuttering"
Góral-Półrola et al. (2015). Evoked-response audiometry (or electric-response audiometry, ERA) is a collective term for techniques which record electrical activity response of the auditory pathway to auditory signals. These techniques allow conclusions about the hearing ability of the subject. According to the website corticalera.com, “the earliest report of relevance was that of Davis who identified the auditory cortical evoked response in 1939 although changes in the EEG evoked by a loud sound had been observed by Berger a decade earlier.” The first ERA technique was the cortical ERA (CERA) in which the cortical response is recorded from the vertex. Many tests had to be done for optimising the detection and analysis of the small bio-electronic signals. One of these tests is described in the paper of the day: “Validation of Evoked-Response Audiometry (Era) in Deaf Children” by Hallowed Davis (1966). It compares the ERA results with “old” testing methods for hearing ability which relied on behaviour signal to auditory signal. The measured ERA volume threshold for different auditory signals for different frequences differed from the voluntary thresholds (measured by behavioral response) just by 0.1dB. So no wonder that cortical ERA was in “widespread clinical use” just a handful of years later (in the 1970s). “Validation of Evoked-Response Audiometry (Era) in Deaf Children”
Hallowed Davis International audiology 5.2 (1966): 77-81 Teleology… don’t confuse that with theology… is a doctrine which deals with the idea that all living and processes in nature follow a certain purpose and are goal orientated. Children are especial receptible for teological explanations. “When asked about properties of natural entities like pointy rocks, children prefer teleological explanations over physical–causal ones, endorsing that rocks are pointy ‘so that animals won’t sit on them’, not because ‘’bits of stuff piled up over time’.” With increasing age this preference to explanations which satisfy the beliefs about intentional causality in nature are replaced by rational explanations. However, people suffering from Alzheimer disease prefer teleological explanations again. So maybe rational explanations don’t replace but cover the teleological explanation. That would mean that teleological explanatory is a sort of explanatory default which can be reactivated when the causal knowledge is damaged. Deborah Kelemen and Evelyn Rossett tested this hypothesis of the co-existence of teleological and rational explanation. They predicted: “Even healthy, schooled adults should display scientifically unwarranted promiscuous teleological intuitions when their capacity to inhibit more primary purpose-based intuitions is impaired by processing demands”. So they designed a test were the participants had to decide if a explanation is good or bad (right or wrong). Indeed they could show that without time limit the participants (university students) prefer rational explanations but “in speeded conditions judged significantly more scientifically unwarranted teleological explanations as correct (e.g., ‘‘the sun radiates heat because warmth nurtures life”)”. So maybe the rational thinking is really just covering our default assumption that in nature everything is connected with each other and everything has a certain function in this interplay? No wonder as the “perfect” evolutionary adaptation of organisms to their environments makes it sometimes hard to keep in mind that it is all a result of random mutation and selection. "The Human Function Compunction: Teleological explanation in adults."
Deborah Kelemen and Evelyn Rossett, 2009 Cognition 111.1 (2009): 138-143. Sorcery accusation can have bad consequences for the defendant. Just remember the witch hunting era which was lead by the inquisition. But there are also more recent examples. For example, in east Java, there are reports about sorcerer-killing from the begin of the 21st century. How can it be that the belief in sorcery is still active? Recording to anthropologists, the modernity of the supernatural lies in an association of evil spirits with capitalism. Therefore, “instead of declining in the modern period, beliefs and practices associated with evil spirits and magic are regularly invoked to explain the experience of capitalism.” For example, in the religion of Java, there are spirits called tuyul which are “spirit familiars who appear like children and can be ‘sent out to steal money’ for their owners.” In order to obtain a tuyul, the sorcerer has to sacrifice ‘either a close relative or a friend’ (Geertz 1960: 21–22). That means that the sorcerer let people suffer for his own gain. He takes advantage of a miserable situation of somebody else which he created by himself and sacrifices relationships in order to benefit from it. That concept is an intense simplification of capitalism. However, as Nicholas Herriman points out in a paper from 2015, capitalism is just one reason for sorcery accusation. Sorcery accusation is also based on conflicts about reciprocity. The connection between evil magic and reciprocity can be seen for example in the Maori concept of hau: “When I receive a gift, I also receive a spirit or hau along with it. If I reciprocate the gift, the hau will return to the original giver. If I do not reciprocate the gift, the hau will stay with me and ‘serious harm might befall me, even death’ (Mauss 1990: 14)”. Indeed, many cases of sorcery which Nicolas Herriman reports from his excursion to Java, include conflicts about reciprocity which don’t have to be connected to capitalism. In many cases the sorcerer wanted something from the person and his request was denied before the affected person got ill because of “evil magic”. So maybe the focus for finding the “sorcerer” who is responsible for the illness is not the question “who benefits from that” but more “who was in a reciprocity relationship with the affected person”. This is maybe why the most “sorcerers” are relatives or neighbours of the affected person. "The Morbid Nexus: Reciprocity and Sorcery in Rural East Java.”
Nicholas Herriman, 2015 The Australian Journal of Anthropology 26.2 (2015): 255-275. I am quite happy that I belong to the persons who had to google endodontic therapy. I feel sorry for every person who knows details about that because of their own experience. Every tooth contains nerves and blood vessels. They are coming through the root and are filling the pulp (the “hole” below the hard surface of the crown). Tooth damage (e.g. by cavity) can damage of the tooth or bacterial infection can lead to an infection of the nerves in the then unprotected pulp. In order to protect the tooth, the dentist removes all nerve tissue and the blood vessels (and other organic material). Desinfection secures that no bacterial infection will occur (again) in this tooth and then the holed tooth is filled with some material and protected by a crown. Herbert Schilder published a paper in 2006, in which he describes the problem of the three dimensional filling of the holed tooth. Filling material can be e.g. solid cores of gutta percha or silver which are connected to the tooth by cementing material. The problem is the complete sealing of the whole hole. The solid core needs to be adapted to the hole form and even then it is hard to guarantee that besides the main root canals all lateral accessory canals are sealed and protected from infection. Therefore, in addition to a solid gutta percha core, gutta percha (according to wikipedia: “a natural polymer prepared from latex from the percha (Palaquium gutta) tree”) can heated up. While gutta percha is heated up its get softer and helps to fill the gap between the the solid core and the tooth and so reduces the amount of cement which is needed. Lets hope we will never need that knowledge. "Filling root canals in three dimensions."
Herbert Schilder Journal of endodontics 32.4 (2006): 281-290. |
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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