Hot Prospects for Ultracold Molecules
With trapped molecules, one would ideally like to achieve three things: reduce translational temperatures to submillikelvin levels; cool a large number of molecules; and put the molecules in a single, and preferably the lowest, rotational vibrational state. Moreover, it would be nice to find a method that enables one to reach these parameters with just about any type of molecule.
Charge Coupled Devices (CCDs) were invented in the 1970s and originally found application as memory devices. Their light sensitive properties were quickly exploited for imaging applications and they produced a major revolution in Astronomy.
CCDs work by converting light into a pattern of electronic charge in a silicon chip. This pattern of charge is converted into a video waveform, digitized and stored as an image file on a computer.
Here is a mascot fight.
Now the Ducks are 2-0. But it is only September.
Hope they can keep the winning streak until the National Champion game.
Definitely we need a little good luck to go that far.
scalar data
All numbers have the same format internally: there are no integer values internal to perl.
Non-Decimal integer literals:
Octal(base 8): 0377 #377 octal, same as 255 decimal (leading zero)
Hexadecimal(base 16): 0xff #FF hex, also 255 decimal
Binary(base 2): 0b11111111 #also 255 decimal
Perl allows underscores for clarity within the literals.
运算符：
%: modulus operator
Strings: literal strings come in two different flavors, single-quoted string literals and double-quoted string literals
Any character other than a single quote or a backslash between the quote marks (including newline characters, if the string continues onto successive lines) stands for itself inside a string. Backslash takes on it’s full power to specify certain control characters. When a string literal is double-quoted, it is subject to variable interpolation （变量内插）besides being checked for backslash escapes.
The simplest way to get a value from the keyboard into a perl program is to use the line-input operator <STDIN>.
The chomp operator: chomp($name). If the string ends in a newline character, chomp can get rid of the newline. The most common use of chomp is: chomp($name=<STDIN>). chomp is a function, has a return value, which is the number of the characters removed. If a line ends with two or more newlines, chomp removes only one. If there is no newline, it does nothing and returns zero.
The undef value and the defined function: variables have the special undef value before they are first assigned. But undef is neither a number nor a string; it is an entirely seperate kind of scalar value. To tell if a value is undef and not the empty string, use the defined function, which returns false for undef and true for everything else.
Thermal lensing is a lensing effect induced by temperature gradients.
Particularly in high power lasers, the heating of the gain medium (e.g. a laser crystal) often causes a significant thermal lens through the following mechanisms:
The gain medium is hotter on the beam axis, compared with the outer regions, typically causing some transverse gradient of the refractive index (→ thermo-optic effect, quantified with the coefficient dn/dT).
Further index changes can be caused by thermally induced mechanical stress (→ photo-elastic effect, quantified with photo-elastic coefficients ρij and the thermal expansion coefficient α).
Mechanical stress can also lead to bulging of the end faces of the gain medium, so that these also cause lensing. This effect can be important for short laser crystals.
Depending on the situation, these effects can have different relative strength and even sign. In many cases, the first mentioned effect (temperature dependence of the refractive index) is most important. (more…)
Perl (Practical Extraction and Report Language)
Unix/Linux 一般都预装了perl, 可以直接拿来写程序；windows下需要在Active Perl(http://www.activeperl.com)下载安装perl的执行环境。如果安装在c:\perl, 需要设定环境变数path,加入c:\perl\bin。
hello world: perl -e ‘print “hello world!\n”‘
编写perl程序只需要一个文字编辑器。 下面是第一个程序：
#！/usr/bin/perl
print “hello world\n”;
执行命令：perl helloworld.pl
在unix下面，可以用chmod把文件变为可执行文件，然后在文件所在目录打：./helloworld.pl
perl的语句用分号（；）分开 ，以井字号（#）作为程序的注释。
Every group in this field has its own way to do computer control.
The content below is from Quantum Gas Lab at University of Aarhus, Denmark.