Giorgio Levy

How to get localhost and username within IDL.

2011-12-08T03:02:00.001-08:00

To get the localhost name and username within idl, you can use the get_login_info function.

IDL>help,/str, get_login_info()

** Structure <88f5c88>, 2 tags, length=24, data length=24, refs=1:

MACHINE_NAME STRING 'PSGJPENDLETON'

USER_NAME STRING 'jimp'

How does a cryo-pump work?

2011-11-06T21:07:00.000-08:00

Previously, I have discussed the cryotorr 8, but how does it work?
A small presentation is shown at the helix website. The cryo-pump uses helium as cooling agent. It cryo-condenses water, nitrogen and argon by frosting them on the condensation array. By using activated charcoal, it cryo-adsorbs hydrogen, helium and neon. Water is cryo-condensed on the first stage array, at ~65K. Nitrogen and argon are cryo-condensed on the second stage at ~12K. Hydrogen, helium and neon are cryo-adsorbed also on the second stage.
By cryo-pumping, we are able to lower the pressure to ~3e-11 Torr from 8e-11 Torr.

If there is no gas load, what is the lowest of the cryotorr 8 cryo-pump?

2011-11-03T21:49:00.000-07:00

Following the previous post, you have installed a new cryo pump cryotorr 8 from Brooks Automation, P/N 8033170. However, the lowest temperature you get after the bake is ~13K, which is almost the same you've reached with the previous cryo-pump.
Shouldn't be lower?
Talking to the technical support, GUTS, the cryo-pump temperature of the second stage should be ~11K. However, it could be easily 1K off and even up to 2K because the silicon diode thermometer is not calibrated. There is no clear-cut reason for a ~13K reading instead of ~11K. It could be due to the calibration curve, or it could be due to a tiny leak. I strongly recommend you to rule out the last possibility by performing an extensive leak-check.
In the case of the second option, where you do not have a calibration curve for the thermometer, it is important how you read the temperature. Brooks automation recommends using a Brooks temperature indicator, P/N 8043459G001; it comes with a "standard" calibration curve. If you are using a Lakeshore 211 temperature controller, it has three different standard calibration curves corresponding to dt470, dt670 and CTI silicon diodes. You can test the display reading of a Brooks temperature indicator against the Lakeshore 211; when the Lakeshore 211 using the CTI calibration curve displays 13.4K, the Brooks temperature indicator will display 12.9K.

Plotting scientific graphs directly in latex

2011-10-27T00:56:00.000-07:00

Previously, I have introduced the latex compiler for text formatting. By using the tikz package; its manual can be found in the CTAN site and here there are some examples. Pgfplots packages uses tikz to plot scientific data (manual).

My cryo-pump has reduced its performance; its operational temperature and base pressure are higher. Why?

2011-10-26T00:33:00.000-07:00

Just to restate the issue: the cryo-pump is connected to a chamber, let's say through a gate valve; after the bake the chamber is at 7e-11 Torr and the cryo-pump operational temperature is at 13.4K. You have leak checked the pump and it is ok. When you open the gate valve, the cryo-pump temperature increases to 14K and the chamber pressure drops only to 5.5e-11 Torr. Eventually it gets to 3.5e-11 Torr. However, the pump temperature slowly increases.

You've got the cryo-pump model: CryoTorr 8 and looked at the cryo-pump manual on the troubleshooting chapter, just to realize that your problem is not described there.

Then you go to the compressor manual with the compressor model: 8200. You check that the compressor static pressure of 250 psi is in the specified range: between 245 and 255 psi. Also, the nominal compressor pressure pulses between 280 and 285 psi which is also within the range given by the manual: 280 and 285psi. Finally you verify the compressor draws 7.95 A which is within the working conditions of the compressor: between 8 and 9A.

After you call the GUTS technical service (24/7/365) from Brooks Automation. They explain you that the average lifetime of the pump is around 5 years; a reduced performance is expected after this. When you give your serial number, you are pointed out that your pump is around 7 years old. These symptoms point to a seals wear off inside the cold head. The solution: either exchange the pump or send it to them. In any case you will get a refurbished one.

Interactive science simulations

2011-10-24T23:37:00.000-07:00

The university of colorado at Boulder has developed interdisciplinary researched-based science simulations: PhET. They are useful to introduce different concepts but, in my opinion, they should not replace the much richer learning process through direct experience.
Have fun!

Como dividir y multiplicar tan solo sabiendo sumar, restar y la tabla del dos

2011-10-23T00:45:00.000-07:00

Este es un interesante capitulo del libro de Adrian Paenza sobre como multiplicar o dividir dos numeros cualquiera tan solo sabiendo sumar, restar y la tabla del dos.

Recommended earthquake safety procedures for BC, Canada

2011-10-23T00:05:00.000-07:00

Last week was the BC shakeout: an awareness day for safety procedures during an earthquake. The basic steps are drop, cover, and hold on. A more comprehensive guide can be found on the Seven steps to earthquake safety and UBC emergency procedures for an earthquake. If you are indoors, they resume to drop, cover, and hold on.
You can check the latest shake status for Canada here. The issue around Vancouver is that the tectonic plates are stuck so if there is a considerable earthquake it will be a big one.

Latex in the cloud

2011-10-18T13:25:00.000-07:00

As far as I know there are three options for using latex in the cloud:
a. latexlab This is very promising; it is still in beta version and some packages are missing.
b. scribtex It is a nice option. It has the package pgfplots and tikz working. The interface is basic.
c. verbosus Nice interface, missing pgfplots package, limited projects in free version.

I am using latexlab for latex notes on the run and keeping the files within Google docs.

Radiation map for Japan

2011-10-13T22:10:00.000-07:00

A friend traveling to Japan asked me how safe is there after the Fukushima Nuclear disaster. This is a radiation dose map for Japan. Below, you will find a brief explanation to understand it, based on a Radiation Awareness Module from the Canadian Light Source.

Ionizing radiation is energy transmitted through a media capable to remove electrons from atoms. During its travel, some of its energy is deposited or lost into the medium. If the energy is deposited in a person, he or she receives a radiation dose. Radiation doses are measured in milli-Sieverts (mSv). The average annual radiation dose to the general population in Canada from natural sources is about 2 mSv per person, and from human-made sources is about 0.6 mSv per person. This is a brief chart of the radiation dose a person can adsorbed from different sources.

Sistema portátil liviano

2011-10-09T20:24:00.000-07:00

Recientemente he descubierto un sistema operativo que arranca desde una llave usb, es confiable, y permite navegar de forma segura: Lightweight Portable Security (LPS).
Esta basado en linux, aunque el entorno simula a windows. Esta desarrollado por el departamento de defensa de los Estados Unidos (DoD) para solucionar el problema del nodo final (end of node problem). Para instalarlo pueden bajar un archivo ISO y grabarlo en un CD or en una llave USB. Para la ultima opción, use unetbootin.
Este sistema es útil porque detecta automáticamente la configuración de la computadora, no deja rastros de navegación en el disco rígido, y permite navegar de forma segura con la ultima tecnología flash y java.

Recursos de Latex en Internet

2011-10-08T21:59:00.000-07:00

Latex es un sistema para preparar differentes textos. (definicion en wiki)
Lo utilizo para publicaciones científicas. Uso texlive como interprete y texstudio como editor. Ambos son independientes del sistema operativo (SO). Una buena guia y manual es The Not So Short Introduction to LATEX2ε.

Con esto es suficiente para comenzar.

2010-08-24T02:39:00.000-07:00

The Happy Prince by Oscar Wilde

When we were little, my brother and I had each a bedtime-stories book. One of my favorites tales was the Happy Prince. I remember that my mother was reluctant to read it and I did not understand why.

Now that I have two boys, I see why. When I was little I did not fully grasp the whole idea. The image of a golden statue talking to a swallow was a nice one. Nowadays, when I try to read it, my voice fails and it is after a lot of effort for self-control that I can keep with it.

This is for me an example of how things change with a little of life experience.

2010-08-20T21:14:00.000-07:00

Ventajas cognitivas del hombre moderno

Un colega de trabajo se preguntaba que ventaja en la educación tiene una persona en la actualidad con respecto a alguien que vivió hace 500 años. Si existiera una máquina del tiempo donde tan solo las personas pueden viajar sin nada material. Cuál sería el mayor cambio que haría debido al conocimiento extra que posee?

En mi opinión el mayor cambio se haría en cuanto a la higiene y prevención de enfermedades. Recién alrededor de 1850, John Snow demostró en Inglaterra que el cólera se transmitía por materias fecales. Debido a eso, se diseño en Londres un sistema de cloacas que reduciría la concentración de desechos humanos en la ciudad, disminuyendo los focos infecciosos. Imaginen como sería el disenio de las ciudades previo a eso.

Una persona en la actualidad, posee los conocimientos mínimos de higiene y prevención de enfermedades así como disminuir su transmisión. Como ejemplo, la construcción de fosas cépticas para las casas, hervir el agua antes de tomarla o cocinar con ella y usar alochol para desinfectar heridas.

2010-08-17T21:49:00.000-07:00

Book review

Recently, I've been contacted by Beverly Hill Times publisher to review a book. The e-mail is:

The Beverly Hills Times Magazine has come across a book about which we are considering running an article. The book presents a theory about the emotional balance of people, with focus on homeostasis, evolution, conservation laws, society, and religion. We are seeking background information on the topics in the book to ensure that all of the information in the book is accurate. We are asking for your assistance because your extensive expertise has been brought to the attention of the Beverly Hills Times Magazine.

As background information on the Beverly Hills Times Magazine, my name is Stephen Takowsky, and I am the publisher of Beverly Hills Times Magazine. This is the only free magazine that goes to the residences and businesses in Beverly Hills, California. We have several prestigious monthly contributors including: Ralph Nader, Erin Brockovich, Ron Paul, and Dennis Kucinich. We maintain close contacts with other media, and our articles have been featured on several media platforms including CNN and TMZ. Our websites focus on gathering heavy traffic for our articles by bringing the key words in our articles to the top of search engines.

For more information on our magazine, you can check out our website at bhtmag.com, or you can Google us by searching for Beverly Hills Times. Your assistance would be greatly appreciated. Our main goal at this point is to determine whether there is any established scientific evidence that tends either to support or invalidate the theory presented in the book. We want to find out if there is any scientific research that is relevant to the premise of the book. The Beverly Hills Times Magazine would give you full credit for any input you provide. We would also consider publishing one of your own articles as trade for your contribution. If you have any questions, please feel free to contact me at Publisher@bhtmag.com
Here is a link to the book: http://www.ofgrandeur.com

If you are interested, we would appreciate having your comments by September 19, 2010.

Thank you for your time.

Stephen Takowsky
Publisher, Beverly Hills Times Magazine

bhtmag.com Publisher@bhtmag.com

Firstly, I was surprised that the author of the book wrote me as the publisher of Beverly Hills Times magazine. This rises a lot of ethical questions.

My review is:

   The terms happiness and sadness are used without proper definitions. There are several assumptions made along the book which are not supported. One example is that pain always produces sadness which is not true as it is the case of masochists. Also an objective description on how to measure the happiness and sadness concept is missing along the book. All of these make this idea vague and imprecise. In the book, the question on how to define and measure these concepts are addressed but not answered. The book develops the idea of balance between these concepts related to an emotional energy, a statement which is not scientific. Below it is explained why not.

   The conservation laws are applied to quantities that are transfered between different systems. They are conserved for an isolated system. In two interacting systems which can exchange them, the amount that one systems receives is the same that the other gives. The best example is energy. For an isolated system its energy is conserved. Within this concept, a statement like the absence of energy defines a new entity does not make any sense.

   Another concept is the existence of two quantities that interact between each other or are the possible states of some measurable property. One example is the head and tail states of a coin. If a coin is tossed and the outcome is registered, it can be either tail or head. When the coin is tossed several times, the probability of measuring tail is 1/2 and head is 1/2. In average, we will measure the same amount of tails and heads. This does not mean that there is a balance law between them but just that both states have the same chance to outcome.

   In the same sense, the concept of emotional balance between happiness and sadness have the same sense that the concept of coin balance between tail and head. Stated otherwise, since these quantities are the properties of our emotions, it could be that there is no such balance, just a probabilistic fact. The concept of emotional energy it does not make any sense because for an isolated system the emotional energy will not be conserved. Before life started on earth the emotional energy was zero since it is associated to life. It later increases with the amount of living things. Therefore is not conserved.