jump to navigation

Capable Modular Robots November 9, 2019

Posted by stuffilikenet in Applications, Awesome, Geek Stuff, Science, Star Trek Technology, Toys, Video.
add a comment

 MIT’s Computer Science and Artificial Laboratory’s M-Block robots can self-assemble into different structures. The little cubes (in development over the last six years) have gained the ability to jump, flip, spin, and recognize each other. A barcode-like system on each face of each cube, allowing them to identify the other cubes around them.

The engineers wanted to see if the M-Blocks could (for example) form a straight line or form a random structure using the new communication algorithms. They waited to see if the blocks could determine how they were connected, and then what direction they would need to move to create that line. They found that 90% of the block swarm knew which motion and guidance to move to accomplish the task. I’m curious to know what the other 10% did…

Engineers hope to create a more substantial swarm of blocks (>16) that can assemble to form more complex structures with new capabilities.

Potential MRSA Treatment August 15, 2019

Posted by stuffilikenet in Awesome, Science.
add a comment

Scientists from UNC (North Carolina, not Northern Colorado) School of Medicine, in a study published in Cell Chemical Biology, found just adding molecules called rhamnolipids

Tobramycin.svg

to aminoglycoside antibiotics, such as tobramycin,

Tobramycin.svg

 

makes them hundreds of times more potent against Staphylococcus aureus, including the strains that are otherwise very hard to kill.

We’re talking about MRSA here, folks.  This is a big damned deal. CDC says there were 119,000 cases of serious bloodstream Staph infections in the United States in the last year for which data is available (2017), of which more than 20,000 were fatal.

Take time to process that.

These rhamnolipids effectively loosen up the outer membranes of S. aureus cells so that aminoglycoside molecules can get into them more easily. In a new study, Conlon, Radlinski and colleagues tested rhamnolipid-tobramycin combinations against S. aureuspopulations that are particularly hard to kill in ordinary clinical practice. The researchers found that rhamnolipids boost tobramycin’s potency against:

  • S. aureus growing in low-oxygen niches;
  • MRSA (methicillin-resistant S. aureus), which are a family of dangerous S. aureus variants with genetically-acquired treatment resistance;
  • tobramycin-resistant S. aureus strains isolated from cystic fibrosis patients;
  • and “persister” forms of S. aureus that normally have reduced susceptibility to antibiotics because they grow so slowly.

They found this effect works in related families of antibiotics including gentamicin, amikacin, neomycin, and kanamycin, for the same reason and on Clostridioides difficile, which is a bit of a killer in its own right.

 

Homework:

Chemical Induction of Aminoglycoside Uptake Overcomes Antibiotic Tolerance and Resistance in Staphylococcus aureus; 

40Hz Light Pulses Stop Alzheimer’s May 10, 2019

Posted by stuffilikenet in Awesome, Brain, Geek Stuff, Science, Star Trek Technology.
add a comment

Neuroscientists at MIT have published a paper which demonstrates that 40Hz pulses of light can somehow inhibit the progress of neurodegeneration in mouse model. This study is designed to figure out how a flickering light could stifle cognitive decline, using two unique mouse models engineered to overproduced the toxic proteins that contribute to neurodegeneration. The animals were exposed to light flickering at 40 Hz for one hour every day for between three and six weeks. It worked a treat;  mice engineered to overproduce tau proteins (that usually cause neurodegeneration) displayed no neuronal degeneration after three weeks of treatment compared to a control group that displayed nearly 20 percent total neuronal loss. The other mouse model, engineered to produce a neurodegenerative protein called p25, displayed no neurodegeneration whatsoever during the entire six weeks of treatment.

At left is the brain of a mouse genetically programmed to develop Alzheimer’s disease. At right,...

The researchers then zoomed in on the light-treated animal’s neurons and microglia to study whether the treatment induced any unusual changes in gene expression. The light-treated mice revealed increased neuronal expression of genes associated with synaptic function and DNA repair. In microglia, the brain’s immune cells, there was a decrease in genes associated with inflammation.

Nobody understands how a 40 Hz flickering light can trigger these specific changes to gene expression deep in the brain, but human trials testing the sound and light treatment in Alzheimer’s patients have already begun.

Note: Adding a 40 Hz auditory tone to the process improved the efficacy of this treatment.  Your elderly parents can benefit from this by using gnuaural, an open-source generator of binaural beats for meditation and other psychological effects.

Homework: https://www.cell.com/neuron/fulltext/S0896-6273(19)30346-0

Malaria Cure in the Offing March 11, 2019

Posted by stuffilikenet in Awesome, Science.
add a comment

Shamelessly stolen words:

“In 2016, 216 million people fell sick due to the Plasmodium falciparum parasite and 441,000 died of malaria, according to the report.

The study demonstrated that a single oral dose of 400 mg DSM265 — given seven days after blood stage infection was experimentally induced in healthy subjects who had not previously been exposed, is sufficient to clear low-level P. falciparum parasitemia.

The study confirmed multiple previous studies collectively comprising more than 100 subjects, which also found that DSM265 could clear the disease-causing, non-sexual stage parasites from infected humans.”

This is far too good a bit of news to not shout from rooftops. My uncle (sort of) suffered from malaria from Guadalcanal in 1945 until he passed away eight years ago. Millions of others are a few years from total cure, possibly in a single dose.

 

No Homework Tonight: Don’t have a cite for this yet; it’s supposed to be in today’s Antimicrobial Agents and Chemotherapy, a journal of the American Society for Microbiology, but I can’t find it.

EXCITING UPDATE: American Society for Microbiology. “Anti-malarial shows promise in human clinical study.”  –don’t ask me what page.

50% More Efficient Nanowire Solar Panels February 21, 2019

Posted by stuffilikenet in Awesome, Science.
add a comment

Gallium arsenide nanowires can convert up to 33% of incident light to electricity if arranged like a stand of trees.  A team at École polytechnique fédérale de Lausanne (EFPL, because my French is merde) has made a prototype of these light funnels and found that it may collect up to twelve times the light.  Where did I get that 50% figure in the headline?  That’s the “in practice” value (33% efficiency), compared to the conversion of silicon-based cells (currently[0] about 20% efficient).

Also, since they are really skinny wires, there isn’t much mass which is good considering the cost of gallium arsenide.  When I say skinny here I mean tens of nanometers thick: “Arrays of nanowires would use at least 10 000 times less gallium arsenide, allowing for industrial use of this costly material. Translating this into dollars for gallium arsenide, the cost would only be $10 per square meter instead of $100 000.”

Right then, let’s review: cheaper, lighter and more efficient.  The team thinks they can mount them on flexible substrates, too, so there should be additional deployment modes.

Homework: Single-nanowire solar cells beyond the Shockley–Queisser limit, Peter Krogstrup, Henrik Ingerslev Jørgensen, Martin Heiss, Olivier Demichel, Jeppe V. Holm, Martin Aagesen, Jesper Nygard & Anna Fontcuberta i Morra

 

[0] See what I did there?

Fluorescent Pink Flying Squirrel February 8, 2019

Posted by stuffilikenet in Mutants, Photography, Science.
add a comment

Think Pink: Texas A&M student aids in discovery of fluorescent pink flying squirrel

Not a punk band name, the North American flying squirrel fluoresces pink at night under ultraviolet light. Not a mistake, either:

“I looked at a ton of different specimens that they had there,” Kohler said. “They were stuffed flying squirrels that they had collected over time, and every single one that I saw fluoresced hot pink in some intensity or another.”

In order to expand the search, the team at Northland College in Wisconsin went to the Field Museum of Natural History in Chicago and gathered more specimens. In all, they researched over 100 specimens ranging across numerous states, all confirming the “pink theory.”

I mean it’s not hunter’s orange, but it’s a start.

Tentacle-nosed Catfish February 8, 2019

Posted by stuffilikenet in Mutants, Photography, Science.
add a comment

sixnewspecie2

This is one of six catfish species recently discovered in Amazonian basin rivers and streams.sixnewspecie1

Cute little creatures, aren’t they?

3D-Printed Flexible Piezoelectric Element January 24, 2019

Posted by stuffilikenet in 3D Printing, Awesome, Science, Video.
add a comment

Mechanical engineers develop process to 3D print piezoelectric materials

New methods to 3D print piezoelectric materials that can be custom-designed to convert movement, impact and stress from any directions to electrical energy have been published in Nature Materials.  The materials can also be activated — providing the next generation of intelligent infrastructures and smart materials for tactile sensing, impact and vibration monitoring, energy harvesting, and other applications. Unlike conventional piezoelectrics, where electric charge movements are prescribed by the intrinsic crystals, the new method allows users to prescribe and program voltage responses to be magnified, reversed or suppressed in any direction.

A factor in current piezoelectric fabrication is the natural crystal used. At the atomic level, the orientation of atoms are fixed. The researchers produced a substitute that mimics the crystal but allows the lattice orientation to be altered by design.

“We have synthesized a class of highly sensitive piezoelectric inks that can be sculpted into complex three-dimensional features with ultraviolet light. The inks contain highly concentrated piezoelectric nanocrystals bonded with UV-sensitive gels, which form a solution — a milky mixture like melted crystal — that we print with a high-resolution digital light 3D printer”.

The material has sensitivities 5-fold higher than flexible piezoelectric polymers. The stiffness and shape of the material can be tuned and produced as a thin sheet resembling a strip of gauze, or as a stiff block. “We have a team making them into wearable devices, like rings, insoles, and fitting them into a boxing glove where we will be able to record impact forces and monitor the health of the user,” said the chief investigator Zheng.

The team has printed and demonstrated smart materials wrapped around curved surfaces, worn on hands and fingers to convert motion, and harvest the mechanical energy, but the applications go well beyond wearables and consumer electronics.

“Traditionally, if you wanted to monitor the internal strength of a structure, you would need to have a lot of individual sensors placed all over the structure, each with a number of leads and connectors,” said Huachen Cui, a doctoral student of Zheng’s and the first author of the Nature Materials paper. “Here, the structure itself is the sensor — it can monitor itself.”

Homework: Huachen Cui, Ryan Hensleigh, Desheng Yao, Deepam Maurya, Prashant Kumar, Min Gyu Kang, Shashank Priya, Xiaoyu Zheng. Three-dimensional printing of piezoelectric materials with designed anisotropy and directional responseNature Materials, 2019; DOI: 10.1038/s41563-018-0268-1

AI Detects Rare Syndromes From Images January 9, 2019

Posted by stuffilikenet in Applications, Photography, Science, Star Trek Technology.
add a comment

Rare disorders often present with patterned discoloration of the epidermis, distortion of features and other visibly-detectable aberrations in appearance. Marfan’s syndrome presents with long, flexible body type. Noonan syndrome may present wide-set eyes, and Down’s syndrome is well-known to nearly everyone. Now, researchers have developed a facial analysis framework, DeepGestalt, using computer vision and deep learning algorithms, that quantifies similarities to hundreds of genetic syndromes based on unconstrained 2D images. DeepGestalt is currently trained with over 26,000 patient cases from a rapidly growing phenotype-genotype database, consisting of tens of thousands of validated clinical cases, curated through a community-driven platform. DeepGestalt currently achieves 91% top-10-accuracy in identifying over 215 different genetic syndromes and has outperformed clinical experts in three separate experiments.

In results published in Nature Medicine, DeepGestalt  outperformed doctors in diagnosing patients with Angelman syndrome and Cornelia de Lange syndrome versus other disorders, and in separating patients with different genetic subtypes of Noonan syndrome.

It’s a neat study in that it controls for a bunch of conditions including ethnicity and gender, so it’s a bit more robust than previous studies.

 

Homework: [PDF] https://arxiv.org/abs/1801.07637

Modest Plasma Globe Hack December 12, 2018

Posted by stuffilikenet in Awesome, Science, Star Trek Technology, Toys, Video.
add a comment

Desktop Van De Graaf Generator December 11, 2018

Posted by stuffilikenet in Awesome, Science, Toys, Video.
add a comment

WANT!

Sodom and Gomorrah: Boom Towns December 6, 2018

Posted by stuffilikenet in Awesome, Brilliant words, Science.
add a comment

This delicious rumor just in from archaeologist Phillip Silvia of Trinity Southwest University and published in a paper by Silvia and co-author (and archaeologist) Steven Collins called “The Civilization-Ending 3.7KYrBP Event: Archaeological Data, Sample Analyses, and Biblical Implications”: the Twin Sin Cities were wiped out 3700 years ago by a meteor burst.[1]

The paper has a lot of juicy facts to corroborate Silva and Colins’ version of events: little glassy bits on surfaces that were exposed at the time (too hot to have been made by fires, but not long lasting enough to melt more than the top layers of things); “large-scale absence of tumbled mudbrick that would be typical of earthquake damage. The mudbrick super-structures of buildings at Tall elHammam and its neighbors are totally “missing” as if they were blown entirely off of their foundations.”[2]; “signature markers of an airburst event include high levels of platinum, typically 600%above normal background levels, and a high platinumpalladium ratio. (Both of these occur in asteroids and meteors, but are not common on Earth.) Signature markers also include a high incidence of scorialike objects (SLOs), frequently in pelletized, spherule forms or agglomerations of melted materials, and a high incidence of magnet-ic spherules.”[3]

There is also a delicious discussion of the effects of such an airburst on the nearby Dead Sea the shock wave would have deposited a layer of salts onto the top soil, destroying it and making it unable to support agriculture for hundreds of years. It only takes a salt content of 13,000 ppm to prevent wheat from germinating, and a salt content of 18,000 ppm to prevent barley from growing. Those thresholds were easily exceeded (60,000 ppm): enough to wipe out an entire civilization’s food supply.

What I personally find so interesting in this business is the ancient city itself, not the colorful destruction thereof and subsequent taking of credit by Jehovah’s nutbags; this was 3700 years ago, and the city was already 2500 years old.  The city itself was the administrative center of the kingdom of Middle Ghor[4], and was protected by a perimeter wall up to 30m (100 ft) thick and up to 15m (50 ft.) high, for a linear distance of over 2.5km. That’s not cheap; must have been quite a sight but I can’t find any population figures for 3700 years ago.

Homework: The CivilizationEnding 3.7KYrBP Event: Archaeological Data, Sample Analyses, Southwest University, 7600 Jefferson NE, Suite 28, Albuquerque, NM 87109

  1. The Tunguska thing is apparently not all that rare.
  2. Boom, baby!
  3. Present in Tunguska, too.
  4. Was there an Inner Ghor and an Outer Ghor?  Or a Left and a Right Ghor?

Wrinkled Vein Grafts Don’t Clot November 30, 2018

Posted by stuffilikenet in Awesome, Science.
add a comment

Usually the veins  in bypass surgery come from the patient’s own leg veins, but sometimes that’s not an option. Synthetic vein grafts can be used but tend to develop clots more than do natural (donor) veins.  University of Pittsburgh researchers have hit upon an interesting strategy for reducing clot formation by wrinkling the vein and then straightening it out again.  Check out the bottom picture, there; it looks like an air-brushed playmate.

Top: A smooth surface after exposure to blood get fouled with platelets. Bottom: A surface that wrinkles while exposed to blood resists fouling.

Not bad. “Our arteries expand and contract naturally, partially driven by normal fluctuations in blood pressure during the cardiac cycle. Our hypothesis is that this drives the transition between smooth and wrinkled luminal surfaces in arteries, and this dynamic topography may be an important anti-thrombotic mechanism in arteries. Our goal is to use this novel concept of a purely mechanical approach to prevent vascular graft fouling by using the heartbeat as a driving mechanism.”

Homework:

Active wrinkles to drive self-cleaning: A strategy for anti-thrombotic surfaces for vascular grafts, LukaPocivavsek, Sang-HoYe,JosephPugar,  EdithTzeng, EnriqueCerda,   SachinVelankar,   William R.Wagner

ISS Timelapse November 30, 2018

Posted by stuffilikenet in Awesome, Music, Science, Video.
add a comment

If you haven’t seen this, I recommend viewing full-sized, with the ambient music provided…or Pink Floyd.

You know you want to.

Wound-healing by Alternating Current November 30, 2018

Posted by stuffilikenet in Applications, Awesome, Science.
add a comment

Abstract Image

Scientists at University of Wisconsin have made bandages that can cut (see what I did there?) wound-healing time from two weeks to three days. By passing small alternating currents through the wound (see above) the bandage encourages the fibroblasts to line up in scaffold formation, speeding recovery. It is thought that “biochemical substances that promote tissue growth” are also encouraged by the current.

Interestingly, the current in this experiment was supplied by nanogenerators in a belt around the patients which uses breathing motions to generate the current.

Homework:Yin Long et al. Effective Wound Healing Enabled by Discrete Alternative Electric Fields from Wearable Nanogenerators, ACS Nano (2018). DOI: 10.1021/acsnano.8b07038 (Am. Chem Soc. journals are paywalled, usually, but this one is available now.  Hurry, hurry, hurry!)

Type II Diabetes Prediction by Skin Autofluorescence November 27, 2018

Posted by stuffilikenet in Awesome, Science, Star Trek Technology.
add a comment

Despite amazing improvements in understanding of diabetes, something like one in ten humans is Type II diabetic.  Take a minute to absorb that; about half a billion people. Very, very obviously better medical tools and interventions are needed, since we as a species seem incapable of eating right (there are other factors, too; I don’t blame anyone for enjoying food). Researchers in the Netherlands and Canada have published a study using skin autofluorescence to detect some markers which accurately predict onset of Type II diabetes in the short term of about four years…unless they die first.

It’s a good study; 72,000 patients. “After a median follow-up of 4 years (range 0.5–10 years), 1056 participants (1.4%) had developed type 2 diabetes, 1258 individuals (1.7%) were diagnosed with CVD, while 928 (1.3%) had died. Baseline skin autofluorescence was elevated in participants with incident type 2 diabetes and/or CVD [(myocardial infarction, coronary interventions, cerebrovascular accident, transient ischemic attack, intermittent claudication or vascular surgery)-ed.] and in those who had died (all p < 0.001), compared with individuals who survived and remained free of the two diseases. Skin autofluorescence predicted the development of type 2 diabetes, CVD and mortality, independent of several traditional risk factors, such as the metabolic syndrome, glucose and HbA1c.”.

In high-tech terms this isn’t tough; a one-inch square is illuminated with 300-420nm UV and the fluorescence at 420-600nm.  They took the ratio of the two.  They did chemical workups on fasting blood samples as well: “On the same day, HbA1c (EDTA-anticoagulated) was analyzed using an NGSP-certified turbidimetric inhibition immunoassay on a Cobas Integra 800 CTS analzser (Roche Diagnostics Nederland, Almere, the Netherlands). Serum creatinine was measured on a Roche Modular P chemistry analyzer (Roche, Basel, Switzerland) and renal function was calculated as estimated (e)GFR with the formula developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) [31]. Total cholesterol and HDL-cholesterol were measured using an enzymatic colorimetric method, triacylglycerol using a colorimetric UV method, and LDL-cholesterol using an enzymatic method, on a Roche Modular P chemistry analyzer (Roche). Fasting blood glucose was measured using a hexokinase method.”

Without doing the rather more expensive bloodwork, a skin fluorescence gizmo could be made cheaply available.  It’s an excellent first step.

Homework:

Manufactured Human Organs November 20, 2018

Posted by stuffilikenet in 3D Printing, Awesome, Brain, Science, Star Trek Technology.
add a comment

Scientists at Tel Aviv University have created human organs (little ones but, hey) from a bit of biopsied tissues.  They separated the cells from the rest, induced pluripotency and built up organs in differentiated cell layers on a gel scaffolding.  They were able to grow cardiac, spinal and cortical cells from the biopsy sample.

This is critical to success: the cells are the patient’s own cells, with little chance of immune system rejection.  These guys (Tal Dvir, Reuven Edri, NAdav Noor, Idan Gal, Dan Peer and Irit Gat Viks) are currently engaged in regenerating an injured spinal cord and an infarcted heart with spinal cord and cardiac implants. They have also begun to investigate the potential of human dopaminergic implants to treat Parkinson’s disease in animal models.

They have big plans for this technology: “We believe that the technology of engineering fully personalized tissue implants of any type will allow us to regenerate any organ with a minimal risk of immune response,” Prof. Dvir concludes.

Homework: Reuven Edri et al, Personalized Hydrogels for Engineering Diverse Fully Autologous Tissue Implants, Advanced Materials (2018). DOI: 10.1002/adma.201803895

Diagnosing Alzheimer’s with AI November 12, 2018

Posted by stuffilikenet in Applications, Awesome, Brain, Science.
add a comment

This is pretty good news if you think Alzheimer’s can be slowed or halted in some way (unproven, but a good idea): researchers funded by NIH have developed a (so far) 100% accurate method of diagnosing Alzheimer’s before any clinical symptoms appear.  The study seems pretty bullet-proof, too: Prospective 18F-FDG PET brain images from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) (2109 imaging studies from 2005 to 2017, 1002 patients) and retrospective independent test set (40 imaging studies from 2006 to 2016, 40 patients) were collected. 90% of the images were used as training data and the rest used as test data.  The learning algorithm developed for early prediction of Alzheimer disease achieving 82% specificity at 100% sensitivity, an average of 75.8 months prior to the final diagnosis.

Figure 2:

Example of fluorine 18 fluorodeoxyglucose PET images from Alzheimer’s Disease Neuroimaging Initiative set preprocessed with the grid method for patients with Alzheimer disease (AD). One representative zoomed-in section was provided for each of three example patients: A, 76-year-old man with AD, B, 83-year-old woman with mild cognitive impairment (MCI), and, C, 80-year-old man with non-AD/MCI. In this example, the patient with AD presented slightly less gray matter than did the patient with non-AD/MCI. The difference between the patient with MCI and the patient with non-AD/MCI appeared minimal to the naked eye.

I do recommend doing your homework (below), since the paper is pretty digestible for the alert layman, and the study itself well structured.

Homework:

  1. Yiming Ding, Jae Ho Sohn, Michael G. Kawczynski, Hari Trivedi, Roy Harnish, Nathaniel W. Jenkins, Dmytro Lituiev, Timothy P. Copeland, Mariam S. Aboian, Carina Mari Aparici, Spencer C. Behr, Robert R. Flavell, Shih-Ying Huang, Kelly A. Zalocusky, Lorenzo Nardo, Youngho Seo, Randall A. Hawkins, Miguel Hernandez Pampaloni, Dexter Hadley, Benjamin L. Franc. A Deep Learning Model to Predict a Diagnosis of Alzheimer Disease by Using 18F-FDG PET of the BrainRadiology, 2018; 180958 DOI: 10.1148/radiol.2018180958

 

Crisis Management Down Under November 8, 2018

Posted by stuffilikenet in Brilliant words, Geek Stuff, Science.
add a comment

"Where have all the bloody teaspoons gone?" is an age old question in the workplace. In an article in the BMJ [not concerned with scatology, but British Medicine] from 2005, researchers at the Burnet Institute in Australia attempt to measure the phenomenon of teaspoon loss and its effect on office life. They purchased and discreetly numbered 70 stainless steel teaspoons (54 of standard quality and 16 of higher quality). The teaspoons were placed in tearooms around the institute and were counted weekly over five months. After five months, staff were told about the research project and asked to complete a brief anonymous questionnaire about their attitudes towards and knowledge of teaspoons and teaspoon theft.

During the study, 56 (80%) of the 70 teaspoons disappeared. The half life of the teaspoons was 81 days (that is, half had disappeared permanently after that time). The half life of teaspoons in communal tearooms (42 days) was significantly shorter than those in rooms linked to particular research groups (77 days). The rate of loss was not influenced by the teaspoons’ value and the overall incidence of teaspoon loss was 360.62 per 100 teaspoon years. At this rate, an estimated 250 teaspoons would need to be purchased annually to maintain a workable population of 70 teaspoons, say the authors.

The questionnaire showed that most employees (73%) were dissatisfied with teaspoon coverage in the institute, suggesting that teaspoons are an essential part of office life. The rapid rate of teaspoon loss shows that their availability (and therefore office life) is under constant assault.

One possible explanation for the phenomenon is resistentialism (the theory that inanimate objects have a natural aversion to humans), they write. This is supported by the fact that people have little or no control over teaspoon migration.

Given the widely applicable nature of these results, they suggest that the development of effective control measures against the loss of teaspoons should be a research priority

Hilarious. But wait; there’s more.

Exasperated by the disappearance, the scientists decided they would measure the phenomenon. Do the teaspoons really disappear over time? The answer was a resounding yes: spoons in research institute tearooms seem to have legs. While good fun, the research is a good example of a study design referred to as "longitudinal".

A longitudinal study uses continuous or repeated measures to follow particular individuals – in this case, teaspoons – over prolonged periods of time. The studies are generally observational in nature: the scientists simply watch and collect data over time. Typically, no external influence is applied during the course of the study. Beyond just working out where all the teaspoons have gone, this study type is also useful for evaluating the relationship between risk factors and the development of disease (for example, heart disease), and the outcomes of treatments over different lengths of time. In this study, the main questions posed by our researchers were to determine the overall rate of loss of teaspoons, and to work out how long it took for teaspoons to go missing.

They purchased 70 teaspoons (16 of which were of higher quality), each one discretely numbered and then distributed throughout the institute. Counts of the teaspoons were carried out weekly for two months, then fortnightly for a further three months. Desktops and other immediately visible surfaces were also scanned for "misplaced" spoons. After five months of covert research, the study was revealed to the institute, and staff were asked to return or anonymously report any marked teaspoons which may have found their way into desk draws or homes.

Good study design

This type of data collection provides a simple example of what makes a good longitudinal study. If we break it down, a longitudinal study needs to:

  • take place over a prolonged period (this study was done over 5 months)
  • be observational in nature (teaspoons were observed and counted, there was no intervention)
  • conducted without external influences (teaspoon users/thieves were not aware they were being studied until the conclusion of the study itself).

Results

 

The results show that 56 (80%) of the 70 teaspoons disappeared during the study, and that the half life of the teaspoons was 81 days (that is, half had disappeared permanently after that time). The study also showed the half life of teaspoons in communal tearooms (42 days) was significantly shorter than for those in research group specific tearooms (77 days). The rate of loss was not influenced by the teaspoons’ value. All of these pieces of information directly answer the main question posed by the researchers.

Conclusions

A longitudinal study is terrific at following individuals or teaspoons over a period of time and observing outcomes. But, by definition, the design means there can be no intervention (as we are just observing a phenomenon). The researchers could not employ a tool or an intervention to prevent spoons from being "misplaced", and the researchers could only report a spoon missing. As the study is observational only, there is no way of finding out what has happened to the spoon, just that it is lost. The authors were able to conclude that the loss of workplace teaspoons was rapid, and their availability in the tearoom was constantly under threat.

Homework: Megan S C Lim et al. The case of the disappearing teaspoons: longitudinal cohort study of the displacement of teaspoons in an Australian research institute, BMJ (2005). DOI: 10.1136/bmj.331.7531.1498

Fit Any Scatter Plot June 7, 2018

Posted by stuffilikenet in Brilliant words, Geek Stuff, Science.
add a comment

A wonderful paper in the archives of the University of Rochester  shows how any random scatter plot can be fit to a curve with enough parameters, and thence a lower number of same is often thought to be a good measure of an expression’s fitness for use…until now. “The mathematician John von Neumann famously admonished that with four free parameters he could make an elephant, and with five he could make it wiggle its trunk…The aim of this short note is to show that, in fact, very simple, elementary models exist that are capable of fitting arbitrarily many points to an arbitrary precision using only a single real-valued parameter θ. This is not always due to severe pathologies—one such model, studied here, is infinitely continuously differentiable as a function of θ. The existence of this model has implications for statistical model comparison, and shows that great care must be taken in machine learning efforts to discover equations from data since some simple models can fit any data set arbitrarily well.”

Tall claim?  Nope.  The author, Steven T. Piantadosi, shows two examples of data points fitted with a simple equation

 

image

can be fit to any arbitrary set of data plots……like these:

image

Mind you, the parameter θ needs to be calculated precisely: ”Both use r = 8 and require hundreds to thousands of digits of precision in θ.”.

Gee whiz (and hilarity) aside, the paper demonstrates the fallacy of using unreasonable models for this sort of algorithmic from-data derivation to create meaning from what might be noise, or Joan Miro’s signature.