tag:blogger.com,1999:blog-34566823554829298052024-03-05T01:52:09.206-08:00Our Curious ExistenceAbout anything and everything that comes to my meandering inquisitive mind as it strolls through lifeUnknownnoreply@blogger.comBlogger19125tag:blogger.com,1999:blog-3456682355482929805.post-21452736641817321872018-04-08T16:10:00.002-07:002018-04-08T16:10:25.077-07:00The bias variance tradeoff<div dir="ltr" style="text-align: left;" trbidi="on">
http://scott.fortmann-roe.com/docs/BiasVariance.html<br />
<br />
This page is easily one of the best explanations of bias, variance and the tradeoff between them!</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-61108415285327782862018-03-17T09:44:00.000-07:002018-03-17T09:50:20.551-07:00A gentle introduction to Gradient Descent<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="font-style: normal; line-height: 100%; margin-bottom: 0in;">
<span style="color: #00cc33;"><span style="font-family: "ubuntu condensed";"><b>A
gentle introduction to Gradient Descent</b></span></span></div>
<div style="font-style: normal; line-height: 100%; margin-bottom: 0in;">
<img align="left" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAC8AAAADCAYAAAADSVbhAAAACXBIWXMAABSnAAAUNAHd6Hd0AAAAPElEQVR4nGP5//8/Awg0PJvV8OP/Tw6GIQA4GNl/NEilNbDABCa8Wlbw8e8X/oF0FLGAn5nnI4rjhyIAABY8ExrDHHjrAAAAAElFTkSuQmCC" />
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="line-height: 100%; margin-bottom: 0in;">
One way to think
about machine learning is as a series of “Optimization” problems
i.e. finding the minimum or maximum of a mathematical function (often
called a loss function). Gradient descent is a workhorse for
optimization and is often employed in neural networks.
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
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Imagine that you are
hiking through a landscape that looks like the Chocolate Hills of the
Philippines and that your objective is to get to the lowest point
amongst these hills.</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpzMkxCtPuSVA5VFUhxGIdHpeYxrmzWa6ZUes4B7_dzurZ35j2MADqJDrFc3BfcCr9biZsolIAGE5SrWBxc-SNQ73EO84jnE37rewiyfUz1tDjBmp2kARXYmpE6sZ2ehiBF07csPv4pOY/s1600/im1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="768" data-original-width="1024" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpzMkxCtPuSVA5VFUhxGIdHpeYxrmzWa6ZUes4B7_dzurZ35j2MADqJDrFc3BfcCr9biZsolIAGE5SrWBxc-SNQ73EO84jnE37rewiyfUz1tDjBmp2kARXYmpE6sZ2ehiBF07csPv4pOY/s640/im1.png" width="440" /></a></div>
<br />
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<br />
<div style="line-height: 100%; margin-bottom: 0in;">
But wait a second!
What does this have to do with machine learning? In fact, it is so
fundamental, that it is easy to miss the intuition! Let’s say you
are trying to build a predictive model. The way you would build the
perfect model is by comparing your prediction against the actual data
and constructing what is known as a loss function. Simplistically,
that could be :-</div>
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<div style="line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Loss
function = Your prediction – Actual data</span></div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="line-height: 100%; margin-bottom: 0in;">
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</div>
<div style="line-height: 100%; margin-bottom: 0in;">
Optimization in this
scenario would be to find the model that reduces the error between
your prediction and the actual data. Said in other words,
optimization aims to find the model that provides the lowest possible
value of the loss function. This hilly landscape can be imagined as
the error for various models and finding the lowest point in the
landscape corresponds to the perfect model!</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="line-height: 100%; margin-bottom: 0in;">
The ‘objective’
function you are trying to optimize during the hike is your height
above sea level. The parameters of this function, known as the
objective, are your latitude and longitude. Gradient descent offers a
set of techniques to iteratively locate the lowest (or highest)
point. Using gradient descent, you can figure out which direction to
take your steps in and how long each step should be.
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="line-height: 100%; margin-bottom: 0in;">
Say that you’ve
stopped to take in the beautiful view of the hills and you stretch
one foot out in every direction around you to feel the ground. The
tilt of your feet as it lands on the ground is the gradient or the
slope. This is exactly the ‘gradient’ in gradient descent too!</div>
<div style="line-height: 100%; margin-bottom: 0in;">
In logical terms,
all of gradient descent can be encapsulated within the following few
lines:-
</div>
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
<div style="line-height: 100%; margin-bottom: 0in;">
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</div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Set initial random parameters (say latitude,
longitude = 43N,45W)</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Calculate height above sea level at these
initial parameters (objective function)</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Repeat until change in objective function is
very small or you’re tired of walking (number of steps has reached
a large value):</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";"> Compute
gradient with given parameter values (lat, long)</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";"> New parameters = Old parameters – Learning
rate * Gradient</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Calculate height above sea level (objective
function) at these new parameters (new objective function)</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";">Is the change in
your height above sea level very small? If so, then stop</span></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtcx-HufdW8-ye8mxt1Ngev89Ag90qQjcDiRVqDsjNjrrOZor3QgfXdZqBZrBqPN8k5oMWAsDVeD31SoqoS2sWaA4zPdZrj5T4P3rzwMisWdCuDDwQzbvjRsh6hgYjBV2tz9J2lysZBR8/s1600/im2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="579" data-original-width="1360" height="272" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtcx-HufdW8-ye8mxt1Ngev89Ag90qQjcDiRVqDsjNjrrOZor3QgfXdZqBZrBqPN8k5oMWAsDVeD31SoqoS2sWaA4zPdZrj5T4P3rzwMisWdCuDDwQzbvjRsh6hgYjBV2tz9J2lysZBR8/s640/im2.jpg" width="440" /></a></div>
<div style="font-weight: normal; line-height: 100%; margin-bottom: 0in;">
<span style="font-family: "lobster";"> </span>
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</div>
<div style="line-height: 100%; margin-bottom: 0in;">
The learning rate
used above determines how fast you arrive at a solution (whether
optimal or not). A large learning rate would imply that the length of
each step you take during your hike is large. You would ‘learn’
quickly with a large learning rate, but you also risk missing the
lowest point in the hill, because you may have just stepped over it.
A smaller learning rate could be exhaustive, but might make for a
very slow process. Imagine a 6 ft human being hiking through these
hills versus an 18ft troll. The human being might cover the entire
hilly landscape thoroughly but take months, while a troll might miss
the lowest point, but take only a few hours. </div>
<div style="line-height: 100%; margin-bottom: 0in;">
<br /></div>
<div style="line-height: 100%; margin-bottom: 0in;">
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</div>
<div style="line-height: 100%; margin-bottom: 0in;">
There are three
variants in gradient descent and they all differ in what information
you use to determine your direction of travel and length of step.
</div>
<ol>
<li>
<div style="line-height: 100%; margin-bottom: 0in;">
Batch
gradient descent
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
The gradient in
batch gradient descent is calculated using the entire available
training data set. Although this ensures that for convex landscapes
a global minima will always be found, you can imagine it being very
slow. Before every step you (the hiker) takes, you compute the
gradient based on <i>all </i><span style="font-style: normal;">available
data. </span>
</div>
<div style="font-style: normal; line-height: 100%; margin-bottom: 0in;">
</div>
</li>
<li>
<div style="line-height: 100%; margin-bottom: 0in;">
Stochastic
gradient descent</div>
<div style="line-height: 100%; margin-bottom: 0in;">
In this case,
before every step that you, as the hiker, take, you stochastically
(or randomly) select a single training data point and use it to
compute the gradient. This can lead to a lot of variation and less
evenly taken steps compared to batch gradient descent since now, the
new step depends on a randomly chosen data point. The nice thing
though is that it is much faster than the batch method.</div>
</li>
<li>
<div style="line-height: 100%; margin-bottom: 0in;">
Mini-batch
gradient descent</div>
<div style="line-height: 100%; margin-bottom: 0in;">
This is the chicago
blend popcorn of the gradient descent world! It uses small batches
of training examples to compute the gradient (not all like in batch
gradient descent and not one like in stochastic gradient descent). A
combination of stability of parameter updates as well as manageable
computation time makes this technique an attractive option when
choosing gradient descent for optimization problems.</div>
</li>
</ol>
</div>
<div style="line-height: 100%; margin-bottom: 0in;">
</div>
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-37523348794974972272016-04-19T20:32:00.001-07:002016-04-19T20:32:51.783-07:00Chicken football<div dir="ltr" style="text-align: left;" trbidi="on">
Not my first foray into comic drawing...but my first public one :)<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBrPDshT6oiWsD9AjRuBG3JtQNgsVUowI3lj4xdBGG7qbwRJQ2Oy5armQExI3T55T11b0ukJeLjTnTFHYcpSIGRPLGJ0NU8kTfkGqJAegClcZJiPnx86PBDAdG_ZNtMmHLB-_Ss5au1uY/s1600/fowl.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBrPDshT6oiWsD9AjRuBG3JtQNgsVUowI3lj4xdBGG7qbwRJQ2Oy5armQExI3T55T11b0ukJeLjTnTFHYcpSIGRPLGJ0NU8kTfkGqJAegClcZJiPnx86PBDAdG_ZNtMmHLB-_Ss5au1uY/s400/fowl.png" width="375" /></a></div>
<br /></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-69968763815429133842014-09-19T06:32:00.000-07:002015-12-28T23:15:57.101-08:00Freshly baked slackware<div dir="ltr" style="text-align: left;" trbidi="on">
I typically run into three problems with a fresh install of slackware (all of two times!!)<br />
1. Anyone (other than root) out there?<br />
useradd <myname><br />
passwd <myname><br />
Typically, I leave my home is installed on a separate unperturbed partition, so to link it up, I simply re-add my old username.<br />
<br />
2. Volume volume people!<br />
Run alsamixer and turn on your speakers :)<br />
<br />
3. Wireless networking<br />
Without preamble...<br />
http://straightedgelinux.com/blog/howto/slackware_userland.html<br />
This is not my work...only a link to the actual article and its printed form<br />
<br />
<iframe height="480" src="https://docs.google.com/file/d/0B-uL3dHSw0ALYmk1clRzb2tJWkU/preview" width="640"></iframe>
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-9271819085069086912013-11-15T06:34:00.001-08:002013-11-17T05:41:18.753-08:00Handy bash and vim tips that I've used from time to time<div dir="ltr" style="text-align: left;" trbidi="on">
<b>BASH</b><br />
1. Copying files while retaining their directory structure<br />
find ~dir1/ -name "*.mat" | xargs -I{} cp {} ~/<destination><br />
The directory structure below ~dir1/ where the *.mat files are found are copied to <destination> retaining the structure<br />
2. Scp-ing only a set of files from multiple directories (using find and then scp-ing those files out retaining directory structure<br />
find -name "*.mat" -print0 | tar --null --no-recursion -czf archive.tar.gz --files-from -<br />
<br />
<br />
<br />
<br />
<b>VIM</b><br />
1. To comment or uncomment a block of code<br />
ctrl+v --> select your block of code --> :norm I# (inserts a # in front of each line) or :norm ^x (removes the first character from each line in the selected block)</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-86315723530841751382013-10-31T07:37:00.003-07:002013-11-17T05:41:49.970-08:00Installing java on your linux machine without removing the native version it comes with<div dir="ltr" style="text-align: left;" trbidi="on">
I like to have all my software installations in a single place so I know exactly what state my machine is in by glancing at a single directory, say ~/Software<br />
My ancient CentOs setup doesn't have jdk 1.7 in its repo, so instead of fooling around with alternatives <shudder>, I downloaded the jdk version I wanted and put it into said ~/Software directory.<br />
<br />
Here's a simple way to go about changing the default version of java that your system picks up without having to uninstall the native java that it comes with.<br />
<br />
1. Switch to su<br />
2. Create a file,say java.sh in /etc/profile.d/ containing :<br />
<br />
#!/bin/bash<br />
<br />
JAVA_HOME=/home/ShankarV/Software/jdk1.7.0_40/<br />
<br />
PATH=$PATH:$JAVA_HOME/bin:<br />
<br />
export PATH JAVA_HOME<br />
<br />
3. Save out the file, and logout and log back in to your machine.<br />
4. To test out your java version, run<br />
java -version<br />
5. To see which executable will be picked up, run<br />
which java</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-10131776890960723822013-09-25T08:18:00.001-07:002013-11-17T05:41:42.303-08:00Installing 32 bit java on my 64 bit CentOs6 machine<div dir="ltr" style="text-align: left;" trbidi="on">
This is a right old pain to do, so unless you really need to, I would say find a way to stick to the native 64 bit jre/jdk install.<br />
As of this writing, the latest jdk version available is 1.7.0_40<br />
<br />
A quick listing of the steps I followed are below. The commands are italicised.<br />
<br />
1. <i>yum erase jdk</i> (to remove the existing 64 bit java devel environment)<br />
<br />
2. Download the x86 version of jdk (the rpm), say jdk-7u40-linux-i586.rpm<br />
<br />
3. <i>yum provides libgcc_s.so.1</i><br />
<i> yum install libgcc-4.4.7-3.el6.i686 </i><br />
(which is what came up as the reqd package from the command above)<br />
<br />
4. <i>yum install jdk-7u40-linux-i586.rpm</i><br />
<br />
5. Check your installation with the usual <i> </i><br />
<i> java -version</i><br />
<br />
In case you want both the 64 and 32 bit versions of java installed, you'll have to muck about with alternatives, which I happily chose to avoid!<i> </i><br />
<br /></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-25801893186878601602013-07-03T09:25:00.006-07:002013-11-17T05:41:59.052-08:00Handy git tricks<div dir="ltr" style="text-align: left;" trbidi="on">
Using Git is a blessing, truly it is. Today is just one of those days when I feel like chopping a limb off because git can't understand what I want it to do.<br />
"Restore a file I deleted from my ide, then revert it to its state when I added that line in, then checkout a single file blah blah jabber jabber"<br />
<br />
Each time I discover a neat trick to do what I want in git, I shall henceforth make a note of it here :)<br />
<br />
<ol style="text-align: left;">
<li><span style="color: purple;">Restore a file that you deleted</span> by accident in the repo or <span style="color: purple;">Undo all the changes in a file</span> but haven't committed yet.</li>
</ol>
git checkout HEAD^ <path to file><br />
<br />
This should bring the file back to the state it is in in the remote repo.<br />
<br />
2. <span style="color: purple;"><span style="background-color: white;">List all the files included in a commit</span></span><br />
<br />
<span style="color: purple;"><span style="background-color: white;"><span style="color: black;">git log master</span></span></span><br />
<br />
<span style="color: purple;"><span style="background-color: white;"><span style="color: black;">find the commit reference from here eg: 7bdf3a80243c7029508357c45bf4b918ce2bab86</span></span></span><br />
<span style="color: purple;"><span style="background-color: white;"><span style="color: black;"> </span> </span></span><br />
git show --name-only 7bdf3a80243c7029508357c45bf4b918ce2bab86</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-54582465061990618802012-09-01T16:14:00.000-07:002013-11-17T05:42:22.584-08:00Cancer killing virus...Are you kidding me?!<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<br />
I couldn't believe my eyes when I stumbled across this nugget online. Why on Earth hasn't this been plastered over the front page of every newspaper, the top of every science feed list or on billboards along the highway!<br />
Before I get ahead of myself and incite an outrage, let me briefly tell you what I understood of the <a href="http://www.telegraph.co.uk/science/9508895/A-virus-that-kills-cancer-the-cure-thats-waiting-in-the-coldc.html">article</a>.<br />
At Uppsala University Hospital in Sweden, Prof Magnus Essand and his team have created a virus that <i>eats</i> cancerous cells. When a healthy cell is infected by a virus, it dies to prevent the spread of the virus to other cells. Cancerous cells change this behaviour and prevent their <i>sacrifice</i> (this is what make cancerous cells evil). But if a virus can be created to take advantage of this very feature of a cancerous cell, it would enter the cell, multiply uncontrollably and cause the cell to 'lyse' or explode, thereby spreading the cancer-munching virus (babies?) to other cancerous cells. This isn't a new idea apparently!<br />
Oddly enough, in the 1890s, an Italian clinician found that prostitutes with cervical cancer showed alleviated symptoms when vaccinated against rabies. He then proceeded to roam the countryside injecting women with dog saliva. (Sigh!). In the 1900s, a 14 old year old boy with lymphatic cancer, found his swollen liver and spleen return to normal size after catch chicken pox. (and you never thought that you would find a bright side to chicken pox!).<br />
The virus that Prof. Essand and his team have is said to attack neuroendocrine tumours (the same kind that assailed Steve Jobs). The virus, however, is in cold storage, refrigerated until it can go into human trials.<br />
To be reasonable, the virus' success in rats doesn't necessarily translate into human viability, but that's what human trials are meant for! Money, is a blocker (surprise surprise). They need 1 million pounds to go through phase 1 and 2 of the trials and 2 million pounds to develop a better variety (I'm not really sure what this is even supposed to mean. Doesn't the virus either do its job or not? what does it get better at with an additional million pounds worth of research?) In any case, the virus remains unnamed and the team has agreed to name it after the person who donates a million pounds. I quote verbatim from the <a href="http://www.telegraph.co.uk/science/9508895/A-virus-that-kills-cancer-the-cure-thats-waiting-in-the-coldc.html">article</a><br />
, <br />
<blockquote>
To donate money to Professor Magnus Essand's research on viral treatments for neuroendocrine cancer, send contributions to Uppsala University, The Oncolytic Virus Fund, Box 256, SE-751 05 Uppsala, Sweden, or visit www.uu.se/en/support/oncolytic. Contributions will be acknowledged in scientific publications and in association with the clinical trial. A donation of £1 million will ensure the virus is named in your honour</blockquote>
<br />
I also found another rather interesting tidbit. The details of the virus have already been published. This no longer allows them to file a patent (who would have thunk!). Without a patent, a pharma company that would have ordinarily take over the expense of the 3rd phase of human trials in order to profit from subsequent manufacturing and distribution when the drug goes commercial, won't think of investing the money. Devoid of an avenue to accrue profits, pharma companies would shrink away into the darkness. Unless....unless the team makes a modification to the virus, and redoes the entire process, this time taking care to file a patent before a publication. Politics in science...is a nasty business.<br />
Here's hoping that the virus does succeed in human trials, that the team does get the money it seeks to continue their research and that patients with NETs (Neuroendocrine tumours) have a lantern bobbing brightly on the horizon.<br />
If this were to succeed, I would be very excited to see how the results could be modified to deal with other kinds of cancers....could we truly be on the cusp of a breakthrough? <br />
Cheering on the Uppsala team, here's wishing them all the very best of luck!<br />
<br />
<br />
Links: http://www.telegraph.co.uk/science/9508895/A-virus-that-kills-cancer-the-cure-thats-waiting-in-the-coldc.html
</div>
Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-3456682355482929805.post-88969058333166838962012-06-26T13:47:00.002-07:002013-11-17T05:42:41.779-08:00Afo the Giant Clove tree<div dir="ltr" style="text-align: left;" trbidi="on">
This was one of the most interesting tidbits to come out of the '<a href="http://news.bbc.co.uk/2/hi/programmes/from_our_own_correspondent/default.stm" target="_blank">From your own Correspondent</a>' podcast (An excellent podcast about events from around the world told in the form of first person narrative stories as bbc's correspondents become immersed characters in the tales)<br />
Its about a giant clove tree on top of an active volcano in Indonesia!<br />
The tree is on the slopes of a volcano on one of the <a href="http://discover-indo.tierranet.com/spiceIslands01.htm" target="_blank">Spice Islands</a> of Indonesia called Ternate. At its peak, it used to be 40 metres tall and 4 metres wide, but sadly all that is left of it today is a stump. No one knows how old it really is, but estimate it to be a 350-400 ancient.<br />
<br />
After the Spanish and Portuguese were routed from the country by the Dutch in 1652, the very first multinational company (called the VOC or the Netherlands United East India Company) formed between them and the East India Company, started to regulate spice exports. They behaved much like MNCs today do; controlling supply artificially to keep demand and prices high. They would allow only 800-1000 tonnes of cloves to be exported per year and the rest of the harvest would be burned or dumped in the sea! Any clove tree that wasn't controlled by the VOC was razed to the ground. Afo escaped this horrendous fate somehow, perhaps because of its remote location<br />
<br />
It seems that man's thirst for money (aka power) is unquenchable, today, 500 years ago and cynically, yet realistically 500 years hence. He apparently doesn't care for anything or anyone that causes so much as a speck on his monetary horizon. That rant aside, what are we to do about our beautiful planet if ravaging her is this deeply ingrained in our psyche?<br />
<br />
Links:<br />
BBC article - http://www.bbc.co.uk/news/magazine-18551857<br />
Spice Islands - http://discover-indo.tierranet.com/spiceIslands01.htm<br />
FOOC podcast link - http://news.bbc.co.uk/2/hi/programmes/from_our_own_correspondent/default.stm<br />
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-60106599374182341672012-03-29T08:13:00.000-07:002013-11-17T05:43:02.333-08:00Matlab and Movie making<div dir="ltr" style="text-align: left;" trbidi="on">
I realize that this is completely against the spirit of my blog, yet I find myself sighing so loudly with relief at having finally been able to make the 'movie making in matlab' process work for me, that I just needed to put it down here (for future reference and for everyone having the same problem)...Believe me, I know how madly annoying it can be to run an 'addframe' command in loop 5000 times, relinquishing control over your screen for an hour, only to find at the end of this excruciating process that the avi is distorted!!!<br />
<br />
In matlab...<br />
<br />
filename = sprintf('images/Pic%04d.jpg', index);<br />
imwrite(image_matrix, filename);<br />
<br />
In the terminal...<br />
ffmpeg -i Pic%04d.jpg -sameq -r 25 outmovie.mp4<br />
or<br />
ffmpeg -i Pic%04d.jpg -sameq -r 25 outmovie.avi<br />
To slow down the movie,<br />
<code>ffmpeg -i Pic%04d.jpg -sameq -r 25 </code><code><code>-vf "setpts=2.0*PTS" </code>outmovie.mp4</code><br />
To speed up the movie,<br />
<code>ffmpeg -i Pic%04d.jpg -sameq -r 25 </code><code><code>-vf "setpts=0.5*PTS" </code>outmovie.mp4</code><br />
<br />
And wala!, I now have a perfect movie :D</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-59230876922657714102011-09-11T19:30:00.000-07:002013-11-17T05:43:17.131-08:00Can machines think?<div dir="ltr" style="text-align: left;" trbidi="on">
<b>These are my impressions after reading Alan Turing's 1950 treatise in MIND on the subject of 'Can Machines Think?'</b><br />
<br />
As i continue to read the articulation of thinking machines by Turing, it seems so incredible that he should have conceived such far reaching ideas as early as 1950!<br />
<br />
An example of 'far reaching' would be in his definition rather the lack thereof of a pinning down means by which thought in the machine may be sought and its similarity to the fashion in which humans are said to 'think'. I quote "May not machines carry out something which ought to be described as thinking but which is very different from what a man does? This objection is a very strong one, but at least we can say that if, nevertheless, a machine can be constructed to play the imitation game satisfactorily, we need not be troubled by this objection".<br />
My own notes at the time that I read this were as follows :<br />
" <style type="text/css">
p, li { white-space: pre-w
</style>he seems to have forseen that the mechanism of 'thought' in the machine is unlikely to be of the same kind as in a human being and chooses to ignore it. <br />
<div style="-qt-block-indent: 0; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; text-indent: 0px;">
If say, a machine were to have used solely machine learning and data mining as a method to find the answers to all the questions of the interrogator, Turing would not have minded it, for he has chosen to give weightage to the ends and not the means. "</div>
<div style="margin: 0px; text-indent: 0px;">
<br /></div>
<div style="margin: 0px; text-indent: 0px;">
Then we come to his definition of the digital computer as a machine that can do anything that a human computer can do. Though, I yet wonder what exactly the 'human computer' is meant to imply. Could it be that in the post world war 2 era, the code breakers et all who crunched numbers are the 'human computers'. But by mentioning this, I deviate from my main intention. His definition of the digital computer is legendary. He states that it should have three components viz.</div>
<div style="margin: 0px; text-indent: 0px;">
1. store</div>
<div style="margin: 0px; text-indent: 0px;">
2. executive unit</div>
<div style="margin: 0px; text-indent: 0px;">
3. control unit</div>
<div style="margin: 0px; text-indent: 0px;">
<br /></div>
<div style="margin: 0px; text-indent: 0px;">
I have also found what my previous job was all about. As a coder/programmer I now know what programming is actually supposed to mean 'constructing instruction tables is programming'.<br />
<br />
He makes a remarkable comment about the notion that scientists always proceed from well-established fact to well established fact without making use of 'unproved conjecture'. In his opinion this is a fallacy. He further notes that as long as fact and ungrounded conjecture are stated upfront, no harm can result from the use of conjecture for it may even lead to new lines of research.<br />
<br />
This line I am yet to understand, but he states that his opinion of the original question of 'Can machines think?' is that 'it is too meaningless to deserve discussion'. !!! I think he might mean that 'Can machines think?' is irrelevant, but 'Are there imaginable discrete state machines that can do well in the imitation game' is what it should be replaced with.<br />
<br />
He has discussed counters to some 8 arguments that stem from diverse areas such as philosophy, Lady Lovelace, Mathematics and even ESP!<br />
This is where I found out that ESP has three forms viz. telepathy, psycho-kinesis, clairvoyance and precognition! His argument against ESP doesn't seem to be very confident. I believe that he did not like the idea of ESP being 'around' despite science and not bothering anyone as long as they chose to ignore it. Albeit he admitted that it might be of special consequence in the particular question of thinking machines. In any case, he seems to have left the doubt lingering (perhaps much to his dislike!).<br />
<br />
He has compared the mind to the skin of an onion. To reveal the inner working, you would need to peel off the layer of skin. In doing so, one would reveal yet another layer to be peeled off. I'm not sure how this ties in with the paragraph of learning machines!<br />
It seems obvious to us now, but the leap that he made from 'let's programme a machine to play the imitation game to mimic an adult human brain to 'let's programme a machine to simulate a child's brain and let it learn via education to become an adult brain' is fantastic! Machine learning's roots!<br />
He admitted that a child machine cannot be subjected to the same teaching/education process that a human child is. Further, do we need to give it legs, eyes and ears? He dismisses the need by citing the example of Helen Keller!!!<br />
<br />
He talks about punishment-reward systems; again the roots of reinforcement learning!<br />
He also talks about how the teacher would be largely ignorant of the internal working of the machine. Unlike the previous idea of a machine having to be told exactly what it needs to do (the progamming part!), and as a counter to Lady Lovelace's argument of a machine being unable to create and being able to do what its been told to do, this new learning machine would be creating and be doing more than it is programmed to do (since it is learning!).<br />
<br />
In his conclusion he mentions that there are two ways in which he thinks machines should be competing with humans.<br />
1. Abstract activity like playing chess<br />
2. Give a machine the best sense organs that money can buy and let it learn as a child does.<br />
<br />
He admits to not knowing which of the two approaches is the ideal one and that both should be tried.<br />
<br />
29 pages of a very interesting read indeed!</div>
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-15035760432106553902011-03-24T23:55:00.000-07:002013-11-17T05:43:27.734-08:00Artificial Trees!<div dir="ltr" style="text-align: left;" trbidi="on">
Now, this is an interesting idea! Given hat man is entirely hopeless at protecting the environment and compelled by some inner voice to make ash out of any remaining beauty in his path, this concept might actually take off, if only for the selfish need that we have for oxygen.<br />
<br />
The idea is this - create artificial trees that would absorb CO2 out of humidity by a technique called humidity swing (more on this later). They would also be equipped with solar panels to create energy to drive this process. Further, a see-saw below the tree would encourage people to play on it thereby creating more energy to be diverted to the absorption process. Excess energy would be used to light up the tree at night which would then serve as a pretty street light!<br />
Hmmm....thats the first thought that came to my mind.<br />
And the next one, what is this humidity swing process anyway?<br />
and the third, what would the tree do with the CO2 it extracts from the humidity?<br />
Oh, and another thing, the tree would be made out of recycled plastic from old bottles and what not.<br />
<br />
<br />
To the second thought....A paper by Klaus Lackner and Allen Wright from Columbia University proposes a method of CO2 capture using a humidity swing sorbent.<br />
Two things here,<br />
1. Humidity swing is the process of raising the relative humidity (called RH ;) ) to a large value for a while and then returning it to normal value.<br />
2. A sorbent is basically an absorbent, a material that absorbs another.<br />
So this is how it works...<br />
1. A dry resin absorbs CO2.<br />
This dry resin consists of +ve ions fixed to a polymer matrix and free -ve ions (OH-)<br />
OH- + CO2 -> HCO3-<br />
<br />
2. The resin is wet with water.<br />
<br />
3. When the CO2 saturated resin reacts with water it releases CO2 at a higher pressure. The resin is then ready to be used again as in step 1.<br />
2HCO3- -> H2O + CO2 + CO3-<br />
This the resin regeneration phase.<br />
<br />
4. Drying of the resin<br />
When the water and CO2 are released, the RH of the resin drops to the original value and it is ready for reuse.<br />
<br />
Now coming to the question of the CO2 that would be stored and then released....where would it be stored? What happens to the CO2 when it becomes time to regenerate the resin? Will the saturated resin be unsaturated in an enclosure that traps the CO2 when it is released from the resin? If so, wha would they do with it once captured? Release it into space? solidify it and bury it?<br />
And a new question that has popped into my head just now....where's the O2 in this process generated from? I wonder if the news articles were misleading.... Rather an unsatisfactory understanding at this stage...but when I do get more detailed information, I'll be sure to update :)<br />
<br />
Links : <br />
The news article in the bangalore mirror - <a href="http://www.bangaloremirror.com/index.aspx?Page=article&sectname=Tech%20-%20Sci%20Tech&sectid=44&contentid=2011031720110317202342266dbf165cd">http://www.bangaloremirror.com/index.aspx?Page=article&sectname=Tech%20-%20Sci%20Tech&sectid=44&contentid=2011031720110317202342266dbf165cd</a> <br />
<a href="http://www.worldarchitecturenews.com/index.php?fuseaction=wanappln.projectview&upload_id=16104">http://www.worldarchitecturenews.com/index.php?fuseaction=wanappln.projectview&upload_id=16104</a><br />
The paper - <a href="http://www.google.co.in/url?sa=t&source=web&cd=1&sqi=2&ved=0CBoQFjAA&url=http%3A%2F%2Fwww.zero.no%2Fzero-konferansen%2F2010%2Finnleggene%2FKlaus_Lackner.pdf&rct=j&q=humidity%20swing%20klaus&ei=mySMTa2WNcjxrQfw27TQDQ&usg=AFQjCNFlkJLQOAb387Hnp6XM_vGIbdSMnw&cad=rja">http://www.google.co.in/url?sa=t&source=web&cd=1&sqi=2&ved=0CBoQFjAA&url=http%3A%2F%2Fwww.zero.no%2Fzero-konferansen%2F2010%2Finnleggene%2FKlaus_Lackner.pdf&rct=j&q=humidity%20swing%20klaus&ei=mySMTa2WNcjxrQfw27TQDQ&usg=AFQjCNFlkJLQOAb387Hnp6XM_vGIbdSMnw&cad=rja</a><br />
<br /></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-45724505449782754082011-03-17T07:33:00.000-07:002013-11-17T05:44:14.255-08:00Planes can fly!<div dir="ltr" style="text-align: left;" trbidi="on">
It all started out with that blasted <a href="http://xkcd.com/803/">xkcd comic</a>! It came up at random and it got my fingers itching to know the answer. So as is my way, i spent an afternoon digging up information, when i finally hit on this <a href="http://amasci.com/wing/airfoil.html">gem</a>.<br />
<br />
There are a couple of things that need to be noted here :<br />
1. Bernoulli effect : "<span class="mContent">when the speed of horizontal flow through a fluid increases, the pressure decreases" quoted from <a href="http://www.wisegeek.com/what-is-the-bernoulli-effect.htm">wisegeek</a> . I especially liked the analogy about a fluid flowing through a narrowing pipe. It speeds up, but considering that there's no change in mass or gravity, the pressure <i>behind</i> the fluid must have to increase compared to that in front to push the fluid faster.</span><br />
<span class="mContent"><br />
</span><br />
<span class="mContent">2. Cambered airfoil : basically this means an unsymmetrical airfoil.</span><br />
<span class="mContent"><br />
</span><br />
<span class="mContent">3. To avoid the suspense :-</span><br />
<ul style="text-align: left;">
<li><span class="mContent">airplanes CAN fly upside down</span></li>
<li><span class="mContent">lift is not because of airfoil shape (What a world do we live in when we can't even begin to trust our own school textbooks!), though it does contribute...read on ;)</span></li>
<li><span class="mContent">airfoils can be symmetrical, asymmetrical and even flat :D</span></li>
</ul>
<span class="mContent">4. Two criteria are essential to an airfoil :-</span><br />
<ul style="text-align: left;">
<li><span class="mContent">It should have a sharp trailing edge</span></li>
<li><span class="mContent">the trailing edge should be aimed diagonally downward</span></li>
</ul>
<span class="mContent">Now to the explanation.</span><br />
<span class="mContent">Oh wait, first off, forget what you read in school about airfoil <i>shape</i> being responsible for anything....hmm, next i'll have to find out what the different shapes are really for!</span><br />
<span class="mContent">One answer that I know of is : the camber is there to prevent stall (reduced lift from upper surface compared to lower surface) and to allow a plane to fly at lower speeds</span><br />
<span class="mContent"><br />
</span><br />
<span class="mContent">Two explanations of the <i>lift</i></span><br />
<span class="mContent">1. <b>Newton's</b><i> </i><b>3rd law and <a href="http://www.wisegeek.com/what-is-the-coanda-effect.htm">Coanda effect</a></b></span><br />
<span class="mContent">2. <a href="http://www.wisegeek.com/what-is-the-bernoulli-effect.htm"><b>Bernoulli effect</b></a></span><br />
<span class="mContent">According to the source that I've cited, both explanations are equally viable and are not <i>competing</i> in any way...they're just <i>both right!</i></span><br />
<span class="mContent">So, on to the first :-</span><br />
<span class="mContent"><i> <b>FIRST EXPLANATION</b></i></span><br />
<span class="mContent">When an airfoil (remember that this can even be a plank of plywood, though it wouldn't be a very good one) goes through the air at a positive angle of attack, both the upper and lower surface of the airfoil are responsible for the lift; a greater portion of which is from the upper surface.<i><b> </b></i>The air along the upper surface is <i>stuck</i> to the surface or attached to it because of the<a href="http://www.wisegeek.com/what-is-the-coanda-effect.htm"> Coanda effect</a> (</span><span class="mContent">fluid or gas stream will hug a convex contour when directed at a tangent to that surface) and hence it flows along the upper surface and since the trailing edge of the wing is aimed downwards (see point 4 above), the air is pushed downwards resulting in a downwash. By Newton's 3rd law, this produces an upward force on the airfoil. Now, to the lower surface. At the +ve <a href="http://www.google.co.in/url?sa=t&source=web&cd=1&ved=0CCAQFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAngle_of_attack&rct=j&q=angle%20of%20attack&ei=xN-BTbywOYrirAea_PXZCA&usg=AFQjCNHhkhnH6QBQVDhWFyXMVcDeMb4LJQ&cad=rja">AoA</a> (fancy abbr for <a href="http://www.google.co.in/url?sa=t&source=web&cd=1&ved=0CCAQFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAngle_of_attack&rct=j&q=angle%20of%20attack&ei=xN-BTbywOYrirAea_PXZCA&usg=AFQjCNHhkhnH6QBQVDhWFyXMVcDeMb4LJQ&cad=rja">angle of attack</a>), the air is pushed downwards by the lower surface, hence the air pushes upwards. These two forces, combine to produce lift. YAY!</span><br />
<span class="mContent"><br />
</span><br />
<span class="mContent"><i><b>REMEMBER</b></i></span><br />
<span class="mContent">Without the downward deflection of air, the AoA is irrelevant since lift won't be created.</span><br />
<span class="mContent"><i><b> </b></i></span><br />
<span class="mContent"><i><b> SECOND EXPLANATION</b></i></span><br />
The leading edge of the airfoil splits the airflow current into two, sending one over the upper edge, and another below the lower edge. If the airfoil has a +ve AoA OR if the airfoil has a classic shape (like we've always been taught), then the stream of air travelling above the airfoil will be well over the upper edge.<br />
Enter Bernoulli...The air flow on the upper edge, since it travels in an arc well over the upper edge, causes the creation of a pocket of low pressure. Air therefore rushes in to fill this low pressure area. However, the air flow along the lower edge, since it collides with it, causes a region of high pressure to develop. This high pressure region slows the air stream on the lower edge down. The pressure differential generates a lift.<br />
<i>But the difference in air velocities over the upper and lower edge is </i><i>caused because of the pressure difference, and not the other way around.</i><br />
<br />
<div>
<span class="mContent">Now that that is all sorted out, lets move on to the airfoil shapes....</span><br />
<span class="mContent"><b>1.</b> <b>The classic shape</b></span><br />
<span class="mContent">From above, we see that the classic shape is good in the case we want large lift even at low speeds. Also, it reduces drag significantly.</span><br />
<span class="mContent"><b>2. A flat wing</b></span><br />
<span class="mContent">This would require a much larger AoA to generate the required lift. Though, it would still develop the pressure differential and downwash in the same explained manner.<b> </b>But the increased AoA would mean a greater drag.</span><br />
<span class="mContent">Helicopter blades are nearly flat. This is preferred because drag is almost not an issue for them. What is required is a maneuverable AoA and airspeed. This is encouraged by nearly flat or tear-drop shaped (symmetrical) blades.</span><br />
<span class="mContent"><b>3. symmetrical wings</b></span><br />
<span class="mContent">A symmetrical or tear drop shaped wing (like most planes do), will resemble the classic shape when positioned appropriately. This is why planes can fly upside down. Both lifting phenomenon still work. </span><br />
<span class="mContent"><b> </b></span><br />
<span class="mContent"><b> </b>A really good explanation is quoted below from <a href="http://www.dynamicflight.com/aerodynamics/airfoils/">http://www.dynamicflight.com/aerodynamics/airfoils/</a></span><br />
<br />
"Airfoil sections are of two basic types, <i><b>symmetrical</b></i> and <i><b>nonsymmetrical</b></i>. <br />
Symmetrical airfoils have identical upper and lower surfaces. They are suited to rotary-wing applications because they have almost no center of pressure travel. Travel remains relatively constant under varying angles of attack, affording the best lift-drag ratios for the full range of velocities from rotor blade root to tip. However, the symmetrical airfoil produces <i><b>less lift</b></i> than a nonsymmetrical airfoil and also has relatively undesirable stall characteristics. The helicopter blade (airfoil) must adapt to a wide range of airspeeds and angles of attack during each revolution of the rotor. The symmetrical airfoil delivers acceptable performance under those alternating conditions. Other benefits are lower cost and ease of construction as compared to the nonsymmetrical airfoil"<br />
<br />
Other sources were :<br />
http://amasci.com/wing/airfoil.html<br />
http://warp.povusers.org/grrr/airfoilmyth.html </div>
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-77271717067303989482011-03-14T04:06:00.000-07:002013-11-17T05:44:27.393-08:00Podcasts<div dir="ltr" style="text-align: left;" trbidi="on">
For the last year and a half, I've been subscribed to a marvelous set of podcasts that i religiously follow. In case, my laptop ever crashes for no given reason or I quit my current place of work (yay!) and so have to give up my mac, on whose iTunes I'm currently subscribed or if a giant meteorite should happen to destroy well....something anyway, here's a record of my favourite podcasts :<br />
<ol style="text-align: left;">
<li><b>Stuff you should know</b> (<a href="http://www.howstuffworks.com/podcasts/stuff-you-should-know.rss">http://www.howstuffworks.com/podcasts/stuff-you-should-know.rss</a>)</li>
<li><b>The Naked Scientists</b> (<a href="http://www.thenakedscientists.com/naked_scientists_podcast.xml">http://www.thenakedscientists.com/naked_scientists_podcast.xml</a>)</li>
<li><b>From our own correspondent</b> (<a href="http://downloads.bbc.co.uk/podcasts/radio4/fooc/rss.xml">http://downloads.bbc.co.uk/podcasts/radio4/fooc/rss.xml</a>)</li>
<li><b>Brain Stuff</b> (<a href="http://www.howstuffworks.com/podcasts/brainstuff.rss">http://www.howstuffworks.com/podcasts/brainstuff.rss</a>)</li>
<li><b>60 second Earth and 60 second Science</b> (<a href="http://www.scientificamerican.com/podcast/sciam_podcast_i_earth.xml">http://www.scientificamerican.com/podcast/sciam_podcast_i_earth.xml</a> and <a href="http://www.scientificamerican.com/podcast/sciam_podcast_i_d.xml">http://www.scientificamerican.com/podcast/sciam_podcast_i_d.xml</a>)</li>
<li><b>A point of view</b> (<a href="http://downloads.bbc.co.uk/podcasts/radio4/pov/rss.xml">http://downloads.bbc.co.uk/podcasts/radio4/pov/rss.xml</a>)</li>
<li><b>The science of everything</b> (<a href="http://fods12.podbean.com/feed">http://fods12.podbean.com/feed</a>)</li>
<li><b>Quirks and Quarks</b> (<a href="http://www.cbc.ca/podcasting/includes/quirksaio.xml">http://www.cbc.ca/podcasting/includes/quirksaio.xml</a>)</li>
</ol>
And here are the podcasts that I wish never died a slow death :'( I miss you guys...please come back!!!<br />
<ol style="text-align: left;">
<li><b>The Thought experiment</b> (<a href="http://feeds.feedburner.com/thethoughtexperiment">http://feeds.feedburner.com/thethoughtexperiment</a>)</li>
<li><b>Discovery Friday news feedbag</b></li>
</ol>
</div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-58469254924042777112011-01-04T19:47:00.001-08:002013-11-17T05:44:42.836-08:00The Two-Way Mirror<div dir="ltr" style="text-align: left;" trbidi="on">
<!--StartFragment--><span style="font-family: Calibri, Verdana, Helvetica, Arial;"><span style="font-size: 11pt;">I went to a friend’s house on new year’s day and she took me on a little tour of her house. Her balcony, curiously enough, had a stepper (exercise machine) and was enclosed with a two-way mirror. For the rest of the evening, I couldn’t sit still! I had to figure out how the bloody thing worked!<br />
So, as soon as I got home, I logged on and checked it out online and walaa! The mystery of the working of the two way mirror was discovered! :D<br />
There are two sides to a pane of glass. The front and the front-of-the-back. <br />
In conventional mirrors, it is the front-of-the-back which is silvered. Therefore, when light falls on it, it is almost completely reflected, leaving anyone on the other side of the mirror with nothing to look at but the painted back end.<br />
However, in a two-way mirror, it is the front that is covered in a very sparse ( not dense ) coating of acrylic or a reflective material. Further, the lighting of the two rooms that this two-way mirror forms an interface between is very important. <br />
Let ‘A’ and ‘B’ be two people...’A’ the prisoner and ‘B’ the cop. <br />
A||||B represents the two people and the mirror in between them.<br />
The room in which ‘A’ is present is very brightly lit while ‘B’’s room is dimly lit. Now, the coating on the mirror, is very thin and would cover say half the molecules on the front surface of the mirror, allowing quite a bit of light to pass through. <br />
Since A’s room has so much light in it, say half the light passes through the two-way mirror into B’s room, allowing B to view A through what seems now like a tinted glass, which is what it exactly is! But B’s room is dimly lit, therefore, the light passing through to A is insufficient for A to see B. A ends up seeing on the light that is reflected off the coating, which is an image of itself. Hence, to A, the two-way mirror seems like a mirror!<br />
If the lighting of the two rooms were to be interchanged, i.e. A’s room be made dim and B’s room be made bright, the situation would be reversed. That is why in cop stories on TV, the prisoner in his room, would try to cup his hand over his eyes and peer through the glass, thus obstructing the bright light of his room so that he may see through! And in the case of my friend’s balcony, she wouldn’t want other people in the surrounding flats to be able to see her on the stepper during the morning hours when it is much brighter outside ( courtesy the sun :) ) while at night, there wouldn’t be much light in the sky anyway to let anyone look in.<br />
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A good way to figure out if you’re stuck at the wrong end of a two-way mirror is to put your finger up against the mirror. If the reflection of your finger is right up against your real finger without any gap, then your up against a two-way mirror. In a conventional mirror, you would notice a gap between your finger and its reflection, because the reflective coating is on the front-of-the-back of the mirror and not on the front ( unlike a two-way mirror ).<br />
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<span style="color: blue;"><u><a href="http://www.wisegeek.com/how-does-a-two-way-mirror-work.htm">http://www.wisegeek.com/how-does-a-two-way-mirror-work.htm</a></u></span></span></span> <!--EndFragment--></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-30346244763881618332010-12-29T02:53:00.000-08:002010-12-29T02:57:13.228-08:00Through the Wormhole<b><span class="Apple-style-span" style="font-size: large;">Episode 5 - How did we get here</span></b><br />
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Just concluded watching the fifth episode of 'Through the Wormhole' on <span class="Apple-style-span" style="color: blue;"><a href="http://topdocumentaryfilms.com/through-the-wormhole-how-did-we-get-here/">http://topdocumentaryfilms.com/through-the-wormhole-how-did-we-get-here/</a></span><br />
Bless the heart of the wise being who uploaded it! :)<br />
<br />
I love the way documentaries give one so much food for thought and make scientists look like rock stars! About this particular one...<br />
The origin of life on Earth is a much speculated and debated scientific and theosophic question. So many scenarios were played out on this episode. My take aways from it were :<br />
<br />
<ul><li>Source 1 of the 'seed' - An experiment conducted by scientists Miller and Ueri in the 50's attempted to replicate the environment during the Hadean period of the Earth involved two flasks, one with evaporating water linked to another with suspended electrodes in it. An electric discharge kept on between the electrodes causes the boiling water to get contaminated with HCn. Also, they found amino acids in the same solutions which are the building blocks of proteins and by extension, life. But even after all these years, proteins were never found in any of the samples of liquid preserved; they remained as unaggregated amino acids itself. </li>
<li>Source 2 of the 'seed' - Meteors bringing amino acids to Earth - It has been shown by experiment that amino acids present within the meteor would have survived the entry through the Earth's atmosphere. This could then have been the seed of life on Earth. This is another possibility for amino acids to have entered the fray of the beginnings of life on Earth ( in contrast to the above explanation).</li>
<li>Source 3 of the 'seed' - Mars could have harboured life before Earth - A meteorite that scientists have discovered the remains of in Antarctica is thought to have come from Mars. This meteorite (ALH84001) indicates signs of magnetization. Mars though is without an atmosphere today. This could indicate that it had an atmosphere and a magnetic field sometime in the past. It could have sustained life at that period. It is also logical because Mars, being half the size of Earth would have cooled faster and settled into a stable state much before Earth and hence could have had all the conditions that Earth now has inorder for it to have been inhabitable by life. It is also possible that after some time, around 4 billion years ago, when Mars started cooling even further, slowly losing its magnetic field and atmosphere, the life on Mars could have hitchhiked on a stray meteor broken out of itslef headed for Earth. This could then have been the third source of amino acids into the primordial soup that was present on Earth. We could all be martians!</li>
</ul><div><ul><li>Life could have evolved in two different forms on the same planet (Earth) - Life in extreme conditions existing in a so-called shadow ecosystem have been discovered to be compatible with arsenic! In lake Mono in California, the levels of arsenic are around 40,000 times the maximum allowable levels. These organisms were collected and subjected to even higher concentrations of arsenic; they survived nonetheless. The reason arsenic is so toxic to human beings is that it molecule is similar to phosphorous and phosphorous is an integral component of the dna molecule. If As replaces the P molecule in dna, it could kill life. So these organisms are akin to alien life form (alien in the sense that they are different to life as we know it and not that they are from outer space). If life could evolve twice over in different ways on the same planet (Earth), then it is nearly impossible to say that life hasn't evolved anywhere else in the universe!</li>
</ul></div><ul><li>Dna is a double helix while rna is a single helix. Rna's building blocks consist of sugar and and base molecules joined together. While it has been possible to create them individually, they have never been able to join them together. At the university of manchester, they tried to create an rna molecule ( something attempted by many many scientists before), but with a twist. This time, they simulated the conditions of Hadean Earth viz. heating, cooling, drying and wetting during the process and created two of the four fundamental building blocks!</li>
</ul><div>The 'seed' for life is stated to be amino acids. In the episode, the sources of this seed are discussed. 'Where could the amino acids have come from?' is addressed. </div><div>This model of the start of life is called abiogenesis i.e. creation of biological life from inanimate chemicals under naturally occurring conditions.</div><div>My questions :</div><div><ul><li>How could it be proved that the meteorite was from Mars.</li>
<li>In the Miller-Ueri experiment all that they used was evaporating water and electricity? Those weren't the only conditions in Hadean Earth I guess.</li>
<li>Given the Miller-Ueri experiment, we know that only amino acids are not sufficient to create life. What are the other ingredients required for the same??</li>
</ul><div>Links :</div></div><div><a href="http://en.wikipedia.org/wiki/Abiogenesis">http://en.wikipedia.org/wiki/Abiogenesis</a></div><div><a href="http://topdocumentaryfilms.com/through-the-wormhole-how-did-we-get-here/">http://topdocumentaryfilms.com/through-the-wormhole-how-did-we-get-here/</a></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-28603816918168664152010-12-28T20:43:00.000-08:002010-12-28T20:43:53.289-08:00YSpeak Project 5 - Why does music affect us in the way it does<!--StartFragment--> <br />
<div class="MsoNoteLevel1CxSpFirst" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;"><sing this song>Rudolph the reindeer<o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><br />
</div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">The careless abandon and romantic nothings echoing from your grandparent’s gramophone,</span><span style="font-family: Calibri; mso-fareast-font-family: Cambria;"> </span><span style="font-family: Calibri;">the muffled sounds of your parent’s favorite tunes on the radio, the songs you crooned along with as a sentimental teenager, the golden oldies you sway to on a lazy Saturday morning and the psychedelic trances you jive to at a late night party. Amazingly, we can all relate to those situations for Music it seems, is omnipresent, at every step of<span style="mso-spacerun: yes;"> </span>the journey that we call ‘life’.<o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><br />
</div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><b style="mso-bidi-font-weight: normal;"><span style="font-family: Calibri;">UNIVERSAL LANGUAGE<o:p></o:p></span></b></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">Music is often touted as the universal language, the underlying stream that runs through all of humanity from time immemorial which binds us together in uncanny harmony. A recently conducted experiment in the Royal Institute of Technology at Stockholm, provided quantitative evidence of the universality of music. A ragtag bunch of volunteers ranging from musical virtuosos to seven year old children, were asked to manipulate songs to enhance the poignancy of specific emotions, like happiness, sadness, anger etc. All of them, landed on the same tempo for each song to bring out the intended emotion. This indicates that music contains some hidden information that evokes similar response irrespective of age, personality, taste or training.<o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><br />
</div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><b style="mso-bidi-font-weight: normal;"><span style="font-family: Calibri;">USE OF MUSIC<o:p></o:p></span></b></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">But, what is the use of Music? Why would anyone want to learn about minor modes, tonic triads or dominant ninths? Learning geometry may be useful for saaaay, building pyramids. Playing with Lego blocks can foster a realization of space. But how does one understand time? That is where music comes in. Paradoxically enough, it also teaches us the rigors of mathematics at the same time as encouraging creativity. Other functional uses of music encompass teaching us to get along with others and suppressing anxiety and stress. Some say that music, by virtue of its individualistic appeal and interminable conundrums is a world shaper; one that can make or break civilizations.<o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><br />
</div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><b style="mso-bidi-font-weight: normal;"><span style="font-family: Calibri;">WHY DO WE LIKE CERTAIN SONGS<o:p></o:p></span></b></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">ASK THE AUDIENCE A QUESTION….Name one of your favorite songs..Why do you like it?<o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">This brings us to an interesting question. Why do we like certain tunes? Is it because of structural features that they might contain? Or is it because they resemble other tunes that we like? In language, unlike music, there are specific syntaxes that define the permissibility and sensibility of one’s utterance. Music, does not have a fixed set of essential features or a rigid structure. <o:p></o:p></span></div><div class="MsoNoteLevel1CxSpMiddle" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><span style="font-family: Calibri;">Let us turn our attention to the second possibility of new favorites resembling our old pet loves. This approach brings up more questions than answers! What do we define as musical resemblance? Well, it is related to how an individual represents melodies in his/her mind. Unfortunately though, nothing spells UNIQUE as much as music does and in each of our minds, different parts of our brain store distinct rhythms, modes and harmonies in unique ways. Beyond that, individuals differ even more. Some cringe at the symmetry that others barely discern, others are elated by a subtle whale song in the background that is imperceptible to most. How do we harmonize the each fading memory of a tune with the next one to be heard? If we like new tunes because they resemble old ones, how then, does our initial liking for music begin? Do we associate some tunes with pleasant experiences? Are they somehow related to our mother’s voice or heartbeat? Are there themes that we find innately likeable? These and many more could hold truth simultaneously, for the only thing that we know with any certainty about our mind is that it is interminably complex. <o:p></o:p></span></div><div class="MsoNoteLevel1CxSpLast" style="margin-left: 0in; mso-add-space: auto; text-indent: 0in;"><br />
</div><div class="MsoNormal"><span style="font-family: Calibri;">Music affects us in ways that are more substantial, direct and poignant than just about every stimuli. Plato allegedly said, “Let me handle the music for one generation and I will control Rome”. We may have conquered the moon, yet we are quite far from understanding music and the mind! Rest assured though, that we don’t need to understand the Beatles to love their Music!</span></div><!--EndFragment-->Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3456682355482929805.post-19713288170075378142010-12-28T18:54:00.000-08:002011-06-05T09:38:57.878-07:00The inchoate list of incipient curiosity (in no particular order)<div dir="ltr" style="text-align: left;" trbidi="on">An ever growing list of random things that I would want to learn/do/see<br />
<br />
<ol><li>Learn origami</li>
<li>Learn Sanskrit ( more than my rudimentary level)</li>
<li>Learn a martial art</li>
<li>Learn to play the guitar</li>
<li>Watch all the episodes of 'Through the wormhole' (for some reason, I always catch the first 10 minutes or the last 15!)</li>
<li>Visit the valley of Kings</li>
<li>Relativity and beyond</li>
<li>Quantum computing/mechanics</li>
<li>Unification of relativity and qm, the purpose of lhc</li>
<li>Explore the history of the world</li>
<li>Tricks that the brain play on our consciousness...unexplained phenomenon attributed to our insufficient understanding of the brain....</li>
<li>Learn Haskell</li>
<li><span style="background-color: lime;">Touch and play with snow </span></li>
<li><span style="background-color: lime;"><span style="background-color: white;">Learn to play chess decently well</span></span></li>
<li><span style="background-color: lime;"><span style="background-color: white;">Create a Daneel Olivaw </span></span></li>
<li><span style="background-color: lime;"><span style="background-color: white;">Be a published author of short stories</span></span></li>
<li><span style="background-color: lime;"><span style="background-color: white;">Learn the detailed history behind each of the references in Billy Joel's 'We didn't start the fire'</span></span></li>
</ol></div>Unknownnoreply@blogger.com0