The Memory Capacity of the Human Brain

The human brain consists of about one billion neurons. Each neuron forms about 1,000 connections to other neurons, amounting to more than a trillion connections. If each neuron could only help store a single memory, running out of space would be a problem. You might have only a few gigabytes of storage space, similar to the space in an iPod or a USB flash drive. Yet neurons combine so that each one helps with many memories at a time, exponentially increasing the brain’s memory storage capacity to something closer to around 2.5 petabytes (or a million gigabytes).

There are actually around 100 billion neurons in the brain. That would up their numbers by two zeros, giving us 250 petabytes of storage.

http://www.scientificamerican.com/article.cfm?id=what-is-the-memory-capacity
http://faculty.washington.edu/chudler/facts.html
http://en.wikipedia.org/wiki/Human_brain

The Ad Hominem Fallacy

We commit the ad hominem fallacy when we think that considerations about a person “refute” his or her assertions. Ad hominem is Latin for “to the man,” indicating that it is not really the subject matter that’s being addressed, but the person.

There are different kinds of ad hominem fallacies. For instance, there is the tu quoque fallacy, where a person’s assertion is rejected because of hypocrisy. Just because a person is being hypocritical doesn’t mean what they’re saying is false.

Ad hominem arguments work via the halo effect, a human cognitive bias in which the perception of one trait is influenced by the perception of an unrelated trait, e.g. treating an attractive person as more intelligent or more honest. People tend to see others as tending to all good or tending to all bad. Thus, if you can attribute a bad trait to your opponent, others will tend to doubt the quality of their arguments, even if the bad trait is irrelevant to the arguments.

Brooke Noel Moore and Richard Parker, Critical Thinking 9th ed. (McGraw-Hill, 2009) 212

Ad hominem. (2012, March 3). In Wikipedia, The Free Encyclopedia. Retrieved 15:04, March 11, 2012, from http://en.wikipedia.org/w/index.php?title=Ad_hominem&oldid=479995034

Using Assembly Language Inside A High-Level Language

By wrapping your assembler in a function, you can write inline assembly code.

Inline assembly code is a straightforward alternative to writing assembly code in external modules. The primary advantage to writing inline code is simplicity because there are no external linking issues, naming problems, and parameter passing protocols to worry about.

Using Microsoft Visual C++, you could write the following short C++ example using the __asm directive:

void TranslateBuffer( char * buf,
  unsigned count, unsigned char eChar )
{
  __asm {
    mov esi,buf
    mov ecx,count
    mov al,eChar
  L1:
    xor [esi],al
    inc esi
    loop L1
  } // asm
}

Kip R. Irvine, Assembly Language For x86 Processors, 6th ed. (Prentice Hall, 2011) 532

“Hello, World!” In Assembly Language 

TITLE Hello World Program (Hello.asm)

.MODEL small
.STACK 100h
.386

.data
message BYTE "Hello, world!",0dh,0ah

.code
main PROC
  mov ax,@data ; initialize DS
  mov ds,ax
  mov ah,40h ; write to file/device
  mov bx,1 ; output handle
  mov cx,SIZEOF message ; number of bytes
  mov dx,OFFSET message ; addr of buffer
  int 21h
  .EXIT
main ENDP
END main

Everything after a semi-colon, on any line, is a comment. “Mov” is short for “move”. The two-letter codes, like ax, ds, ah, bx, etc., are the names of registers, which are very small amounts of memory located directly on the chip.

Assembler is a one-to-one mnemonic representation of machine code, so it offers total freedom, but at the cost of being as low-level a programming language as possible.

Each assembly language program is written for a particular processor family. This one is written for the x86 processor type, i.e. Intel and AMD chips. Furthermore, this code is written for the MASM assembler, created by Microsoft, and designed for programming x86 processors on a Windows machine.

BTW, calling assembly language “assembler” is a bit wrong-headed, as an assembler is a particular program that converts assembly language into machine code. However, it’s a convenient term, and it’s widely used.

Kip R. Irvine, Assembly Langugage For x86 Processors, 6th ed. (Prentice Hall, 2011) 572

The Three Domains Of Life On Earth

All species fall into one of three domains, the broadest (most inclusive) taxonomic category. … Bacteria, Archaea, and Eukarya. Species in domains Bacteria and Archaea are superficially similar to one another; all are single-celled prokaryotes, meaning that their DNA is free in the cell and not confined to an organelle called a nucleus. Major differences in DNA sequences separate these two domains from each other. Domain Eukarya, on the other hand, contains all species of eukaryotes, which are unicellular or multicellular organisms whose cells contain a nucleus.

We fall into the eukaryote domain. Pretty much everything we think of as life falls into that domain.

All three domains are further subdivided into kingdoms.

Three of these kingdoms–Animalia, Fungi, and Plantae–are familiar to most people. Within each one, organisms share the same general strategy for acquiring energy. For example, plants are autotrophs. Fungi and animals are consumers, although they differ in the details of how they obtain food. But the fourth group of eukaryotes, the Protista, contains a huge collection of unrelated species. Protista is a convenient but artificial “none of the above” category for the many species of eukaryotes that are not plants, fungi, or animals.

Mariëlle Hoefnagels, Biology: Concepts and Investigations, 2nd edition. (McGraw-Hill, 2012) 9

Plant Stomata

Plants obtain their three most abundant elements (C, H, and O) from water and the atmosphere. Water (H2O) enters the plant through the roots … Carbon and oxygen atoms come from the atmosphere in the form of CO2 gas, which diffuses into the leaf or stem through pores called stomata.

So a plant uses a stoma to exchange gasses.

In botany, a stoma (also stomate; plural stomata) is a pore, found in the leaf and stem epidermis that is used for gas exchange. … Air containing carbon dioxide and oxygen enters the plant through these openings where it is used in photosynthesis and respiration, respectively.

Stomata tend to open at times of high light intensity and high humidity. Because they’re saturated with water vapor, they have to lose some water before they can take in carbon dioxide.

Mariëlle Hoefnagels, Biology: Concepts and Investigations, 2nd edition. (McGraw-Hill, 2012) 477

Stoma. (2012, January 26). In Wikipedia, The Free Encyclopedia. Retrieved 14:41, February 27, 2012, from http://en.wikipedia.org/w/index.php?title=Stoma&oldid=473388848