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Posts tagged “science

Day #22 : Parametric vs. NonParametric Statistics – 365 DoA

How Mean Meme

Technically we could call this parametric statistics part 2. However, since we are covering nonparametric statistics and more importantly the difference between parametric and nonparametric statistics, it would seem that this title makes more sense. As usual with a continuation, you probably want to start at the beginning where we define parametric statistics. Ready to get started?*

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Day #21 : Defining Parametric Statistics – 365 DoA

normal-distribution

It’s halloween time, we are talking about normally distributed data, so this fits, and I don’t want to hear otherwise!

Well my lovely readers, we’ve made it to the three week mark, 5.7% of the way through! Okay maybe that doesn’t seem like a big deal written like that, but hey it’s progress. So last post we had our independence day, or rather defined what it meant to have independent events vs. dependent events. We also said it was an important assumption in parametric statistics that our events are independent, but then we realized we never defined what parametric statistics even is, oops. So let’s stop dragging our feet and talk parametric statistics!*

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Day #20 : Independent Events – 365 DoA

correlation

By: xkcd

 

Because we introduced the central limit theorem last post, it’s time to introduce another important concept. The idea of independent events, while this may seem intuitive, it is one of the assumptions we make in parametric statistics, another concept we will define, but for now let’s jump into independence.*

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Day #19 : The Central Limit theorem – 365 DoA

 

 

CLT

Well here we are again, if you recall from our last post, we talked Bonferroni Correction. You may also recall that when the post concluded, there was no real topic for today. Well after some ruminating, before we jump into more statistics, we should talk about the central limit theorem. So let’s do a quick dive into what that is and why you should know it!*

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Day #18 : The Bonferroni Correction – 365 DoA

Keep calm and do the Bonferroni corrrection

Keep calm and do the Bonferroni corrrection

By now we are masters of statistics… right? Okay, not really, but we are getting there. So far we’ve covered two types of errors, type 1 which you can read about here, and type 2 which you can read about here. Armed with this new knowledge we can break into a way to correct for type 1 errors that come about from multiple comparisons. Sound confusing? Well, not for long, let’s break it down and talk Bonferroni.*

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Day #17 : Type 2 errors – 365 DoA

 

cat asleep

Last post we did a quick bit on type 1 errors. As with anything, there is more than one way to make an error. Today we are talking type 2 errors! They are related in the sense and we’ll go over what that means and compare the two right… now!*

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Day #16 : Type 1 errors – 365 DoA

tiny dog yawning

tiny dog yawning

We did it, we cracked the coin conundrum! We managed the money mystery! We checked the change charade! We … well you get the idea. Last post we (finally) determined if our coin was bias or not. Don’t worry, I won’t spoil it for you if you haven’t read it yet. I actually enjoyed working through a completely made up problem, so if you haven’t read it, you really should. Today we’re going to talk dogs, you’ll see what I mean, so let’s dive in.*

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Day #15 : Significance, Part 3 – 365 DoA

Standard_deviation

Where does our observation fall on the probability density function?

It looks like we’ve arrived at part 3 of what is now officially a trilogy of posts on statistical significance. There is so much more to say I don’t want to quite call this the conclusion. Instead, let’s give a quick review of where we left off and we can get back to determining if an observed value is significant.*

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Day #14 : Significance, Part 2 – 365 DoA

Bar graph showing z score across trials
Bar graph showing z score across trials

Z-score bar graph that I made just for all of you using some data I had laying around. If you’re new to statistics it may not make sense, but rest assured we will make sense of it all!

Well here we are two weeks into 365DoA, I was excited until I realized that puts us at 3.8356% of the way done. So if you remember from last post we’ve started our significance talk, as in what does it mean to have a value that is significant, what does that mean exactly, and how to do we find out? Today is the day I finally break, we’re going to have to do some math. Despite my best efforts I don’t think we can finish the significance discussion without it and still manage to make sense. With that, let’s just dive in.*

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Day #13 : Significance, Part 1 – 365 DoA

Normally distributed data shown using a histogram plot
Normally distributed data shown using a histogram plot

Histogram of normally distributed data. It looks very… nomal. No it really is normally distributed, read on to find out what that means and how we can use it.

If you’ve read my last post I hinted that today we would discuss filtering. Instead I think I want to take this a different direction. That isn’t to say we won’t go over filtering, we most definitely will. Today I want to cover something else though, significance. So you’ve recorded your signal, took an ensemble average, and now how do we tell if it actually means something, or if you are looking at an artificial or arbitrary separation in your data (IE two separate conditions lead to no difference in your data). Let’s look at significance.*

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Day #12 : Signal, cutting through the noise – 365 DoA

example data

45 separate trials of very noisy data with the average of those trials (black). Believe it or not, this is actually very useful and very real data from something I am currently working on.

Noise, it can be troublesome. Whether you are studying and someone is being loud or you are trying to record something, noise is everywhere <stern look at people who talk during movies>. Interestingly enough the concept of noise in a signal recording sense isn’t all too different from dealing with talkative movie goers, so let’s talk noise!*

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Day #11 : Why even use the spectrogram? – 365 DoA

rotated spectrogram showing all three dimensions
rotated spectrogram showing all three dimensions

A spectrogram plot rotated so we can see all three dimensions.

So you wanna use a spectrogram… but why? What does a spectrogram do that we can’t do using some other methods for signal processing? As it turns out, there is a lot of reasons you may want to use the spectrogram and today we are going to cover some of those reasons and number four may shock you! (okay not really, what do you think this is a clickbait website?)*

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Day #10 : Spectrogram vs. the banana of uncertainty – 365 DoA

banana

The banana of uncertainty (okay, it’s not a real banana)

Well ten days in and we’ve just introduced the idea of the spectrogram. While a lot of this information is just the broad strokes, I like to think that we’ve covered enough to give you a good idea about how to use these tools and what they are used for. However, we do need to discuss a limitation to the spectrogram, something called the banana of uncertainty, okay not quite the name, but you’ll see why I keep calling it that.*

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Day #9 : Reading a Spectrogram – 365 DoA

rotated spectrogram showing all three dimensions
other example

Definitely not the same spectrogram as yesterday, no really look. Now for the part where I tell you how to read this thing…

Last post we introduced a new tool in our arsenal of signal processing analysis, the spectrogram. Without knowing how to read it, it just looks sort of like a colored mess. Don’t get me wrong, it is an interesting looking colored mess, but a mess nonetheless. Well today we are going to talk about how to interpret the plot and why exactly we would ever use this seeming monstrosity.*

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Day #8 : The Spectrogram Function – 365 DoA

Spectrogram

Example spectrogram from some data I had recently processed

To (somewhat) continue with our signal processing theme that we have going on at the moment, over the next few days, let’s look at something called the spectrogram. It’s three dimensions of fun!*

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Day #3 : Power Spectral Density Overview – 365 DoA

In our last post we introduced the two main characters in this story of spectrogram. On one end we have Welch’s method (pwelch) on the other end we have the Thomson multitaper method (pmtm). As promised here is a awful basic breakdown of why is more than one way to compute power spectral density (in fact there are several, far more than the two I’m talking about). So, let’s just dig right in!*

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Day #2 : Power Spectral Density (pmtm) – 365 Days of Academia

Day 2 - EKG

A example EKG signal

This is a (somewhat) continuation on what we were discussing in the previous post. We covered the pwelch MATLAB function, this time we will cover the PMTM function, this function uses the Thomson multitaper method to calculate power spectral density. We can do a deep dive into the differences between the two next time, but for now let’s talk about the command itself.*

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The power of indifference an open letter to the scientific community

indifference

Suddenly your absent-minded thoughts are shattered by a loud noise. Quickly you look around, to the left of you, you see it, and a child has been shot, you see them bleeding heavily. People are standing around with their phones, some calling emergency services, some filming, but most looking confused and scared. No one is actively trying to help; you hear that they are afraid that the person, or persons, who shot the child is still around. What do you do next, do you choose indifference, or do you help?

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Trumped: Why the election is a symptom of a bigger problem

Donald trump hands

Donald trump hands

Right now you are probably thinking that I am going to unleash some poorly thought out diatribe about president elect Trump. No, that is not going to happen. It is not going to happen because he is not the problem, you are the problem, I am the problem, and we are the problem. That goes for those of you who are atheists, Catholics, Muslims, conservatives and liberals, or anything in-between.

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The science behind real life zombies

Zombies: Science Fiction vs. Fact

zombies ahead

In the spirit of Halloween we bring you the science fact and fiction behind the undead. Zombies, those brain loving little guys, (and girls) are everywhere. Sure, we are all familiar with the classic  zombie, but did you know that we aren’t the only zombie lovers out there? It turns out that nature has its own special types of zombies, but this isn’t a science fiction movie, this is science fact! Sometimes fact can be scarier than fiction, so let’s dive in.

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Study uncovers brain changes in offending pedophiles

pedophiles

pedophiles

New research reveals that certain alterations in the brain may be present in pedophiles, with differences between hands-on offenders and those who have not sexually offended against children.

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Your BMI might affect your brain function

brain wieght

brain wieght

There are plenty of reasons it’s important to maintain a healthy weight, and now you can add one more to the list: It may be good for your brain. Researchers have found that having a higher body mass index, or BMI, can negatively impact cognitive functioning in older adults.

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A new view of the immune system

t cells

t cells

Pathogen epitopes are fragments of bacterial or viral proteins. Attached to the surface structure of cells, they prompt the body’s immune system to mount a response against foreign substances. Researchers have determined that nearly a third of all existing human epitopes consist of two different fragments. Known as ‘spliced epitopes’, these types of epitopes have long been regarded as rare. The fact that they are so highly prevalent might, among other things, explain why the immune system is so highly flexible.

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Oligodendrocyte selectively myelinates a particular set of axons in the white matter

axon

axon

There are three kinds of glial cells in the brain, oligodendrocyte, astrocyte and microglia. Oligodendrocytes myelinate neuronal axons to increase conduction velocity of neuronal impulses. A Japanese research team found a characteristic feature of oligodendrocytes that selectively myelinate a particular set of neuronal axons.

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Cold medicine could stop cancer spread

cold medicine

cold medicine

Bladder cancer is the seventh most common cancer in males worldwide. Every year, about 20,000 people in Japan are diagnosed with bladder cancer, of whom around 8,000–mostly men–succumb to the disease. Bladder cancers can be grouped into two types: non-muscle-invasive cancers, which have a five-year survival rate of 90 percent, and muscle-invasive cancers, which have poor prognoses.

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Female brains change in sync with hormones

brain

brain

Although it has already been known for some time that the brain does not remain rigid in its structure even in adulthood, scientists have recently made a surprising discovery. The brain is not only able to adapt to changing conditions in long-term processes, but it can do this every month.

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Untangling a cause of memory loss in neurodegenerative diseases

memory loss

memory loss

Tauopathies are a group of neurodegenerative disorders, including Alzheimer’s disease that are characterized by the deposition of aggregates of the tau protein inside brain cells. A new study reveals that the cutting of tau by an enzyme called caspase-2 may play a critical role in the disordered brain circuit function that occurs in these diseases.

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High cholesterol triggers mitochondrial oxidative stress leading to osteoarthritis

knee problems

knee problems

High cholesterol might harm more than our cardiovascular systems. New research using animal models suggests that high cholesterol levels trigger mitochondrial oxidative stress on cartilage cells, causing them to die, and ultimately leading to the development of osteoarthritis.

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Vitamins A and C help erase cell memory

epigenetics

epigenetics

Vitamins A and C aren’t just good for your health, they affect your DNA too. Researchers have discovered how vitamins A and C act to modify the epigenetic ‘memory’ held by cells; insight which is significant for regenerative medicine and our ability to reprogramme cells from one identity to another.

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Doc versus machine

webMD cancer scare

webMD cancer scare

Increasingly powerful computers using ever-more sophisticated programs are challenging human supremacy in areas as diverse as playing chess and making emotionally compelling music. But can digital diagnosticians match, or even outperform, human physicians? The answer, according to a new study, is “not quite.”

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New sensor material could enable more sensitive readings of biological signals

transhuman

transhuman

High-tech prosthetics, computers that are controlled by thought, the ability to walk or even move again, these are just a few of the promises of technology. Unfortunately, while the tech is — mostly — up to the challenge, getting the biology side of things to cooperate has been difficult at best, but that could change. Now, scientists have created a material that could make reading biological signals, from heartbeats to brainwaves, much more sensitive.

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Concentrating on the social billions

social media

social media

Using online social media does not lead to long-term problems with our ability to concentrate, according to new research. We are social animals, so it is really no surprise that billions of us now use online tools to communicate, educate and inform each other. The advent of social media and social networking has nevertheless been phenomenally rapid.

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First demonstration of brain-inspired device to power artificial systems

memristor

memristor

New research has demonstrated that a nanoscale device, called a memristor, could be used to power artificial systems that can mimic the human brain. Artificial neural networks (ANNs) exhibit learning abilities and can perform tasks which are difficult for conventional computing systems, such as pattern recognition, on-line learning and classification.

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Mental illness genetically linked to drug use and misuse

anxiety depression

anxiety depression

There are many reports of drug use leading to mental health problems, and we all know of someone having a few too many drinks to cope with a bad day. Many people who are diagnosed with a mental health disorder indulge in drugs, and vice versa. As severity of both increase, problems arise and they become more difficult to treat. But why substance involvement and psychiatric disorders often co-occur is not well understood.

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Scientists find new path in brain to ease depression

peter pan come rescue me

peter pan come rescue me

Scientists have discovered a new pathway in the brain that can be manipulated to alleviate depression. The pathway offers a promising new target for developing a drug that could be effective in individuals for whom other antidepressants have failed. New antidepressant options are important because a significant number of patients don’t adequately improve with currently available antidepressant drugs.

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Revising the meaning of ‘prion’

mad cow disease

mad cow

A team of scientists are redefining what it means to be a prion–a type of protein that can pass heritable traits from cell to cell by its structure instead of by DNA. Although prions are infamous for causing Creutzfeldt-Jakob disease, fatal familial insomnia, and bovine spongiform encephalopathy, commonly known as mad cow’s disease, the present study indicates that prions identified in yeast, and possibly in plants, and other organisms may be beneficial.

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For women, caffeine could be ally in warding off dementia

dementia coffee drinking

dementia coffee drinking

Among a group of older women, self-reported caffeine consumption of more than 261 mg per day was associated with a 36 percent reduction in the risk of incident dementia over 10 years of follow-up. This level is equivalent to two to three 8-oz cups of coffee per day, five to six 8-oz cups of black tea, or seven to eight 12-ounce cans of cola.

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Sugar gives bees a happy buzz

simpson sugar mound

simpson sugar mound

An unexpected sugary snack can give bees a little buzz and appears to lift their mood, even making them optimistic, according to research that suggests pollinators have feelings, too. Since emotions are subjective and difficult to measure—particularly in animals—researchers looked at how bees’ behavior changed after they were given a sip of sucrose solution.

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Nature or nurture: is violence in our genes?

dna violence

dna violence

Nature or nurture? The quest to understand why humans kill one another has occupied the minds of philosophers, sociologists and psychologists for centuries. Are we innately violent, as Englishman Thomas Hobbes postulated in the 1650s, or is our behaviour influenced more by the environment we grow up in, as Jean-Jacques Rousseau theorised a century later?

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Omega-3 fatty acid stops known trigger of lupus

fish oil

fish oil

A team of researchers has found that consuming an omega-3 fatty acid called DHA, or docosahexaenoic acid, can stop a known trigger of lupus and potentially other autoimmune disorders. DHA can be found in fatty, cold-water fish and is produced by the algae that fish eat and store in their bodies. It can be found in fish oil supplements as well, used by more than 30 million Americans.

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Children could point the way to new HIV treatments

HIV Aids

HIV Aids

Children with HIV who can resist the disease progressing could point the way to new treatments for HIV infection that are more widely applicable to infected adults and children alike, an international team of researchers has found.

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Research team may have observed building blocks of memories in the brain

memory

memory

A team of researchers has observed what they believe are the building blocks of memories in a mouse brain. In their paper, the researchers describe how they caused certain neurons to become illuminated when they fired, allowing them to watch in real time as memories were made and then later as they were replayed while the mouse was sitting idle.

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The unintended consequences of almond milk on California

almond milk

almond milk

A new study using aerial imagery across the state of California has found that converting land to grow almonds between 2007 and 2014 has led to a 27% annual increase in irrigation demands—despite the state’s historic drought. The expansion of almonds has also consumed 16,000 acres of wetlands and will likely put additional pressure on already stressed honeybee populations.

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Why do more men than women commit suicide?

Depression

Depression

Why do more men die when they attempt suicide than women? The answer could lie in four traits, finds scientists. There are over 6,000 British lives lost to suicide each year, and nearly 75 per cent of those are male. However, research has found women are more likely to suffer from depression, and to attempt to take their own life.

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Linking perception to action

perception

perception

Researchers studying how the brain uses perception of the environment to guide action offer a new understanding of the neural circuits responsible for transforming sensation into movement.

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Historical analysis examines sugar industry role in heart disease research

high sugar content

high sugar content

Using archival documents, a new report examines the sugar industry’s role in coronary heart disease research and suggests the industry sponsored research to influence the scientific debate to cast doubt on the hazards of sugar and to promote dietary fat as the culprit in heart disease.

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Protect kids from toxic secondhand smoke, experts urge

second hand smoke

second hand smoke

It’s advice most smokers with children probably take lightly, but they shouldn’t. Parents and policy advocates should take a “zero tolerance” approach to exposing children to secondhand cigarette smoke, which can be responsible for lifelong cardiovascular consequences in addition to respiratory and other health issues.

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Potentially harmful chemicals widespread in household dust

toddlers playing

toddlers playing

Household dust exposes people to a wide range of toxic chemicals from everyday products, according to a new study. A multi-institutional team conducted a first-of-a-kind meta-analysis, compiling data from dust samples collected throughout the United States to identify the top ten toxic chemicals commonly found in dust.

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Physicists retrieve ‘lost’ information from quantum measurements

quantum mechanics

quantum mechanics

Typically when scientists make a measurement, they know exactly what kind of measurement they’re making, and their purpose is to obtain a measurement outcome. But in an “unrecorded measurement,” both the type of measurement and the measurement outcome are unknown.

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The new findings heart repair research

broken heart

broken heart

Scientists trying to find ways to regenerate a damaged heart have shed more light on the molecular mechanisms that could one day make this a reality.  Whilst other organs such as the liver can regenerate, the heart muscle has very little ability to do so after suffering damage, such as a heart attack.
In the womb the body is able to produce heart muscle cells but soon after birth it effectively stops producing them.

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