Wednesday, July 16, 2008

The Body Surface Area

Today I deployed my first Google application developed with the Google app engine (GAE). You have to be connected to the internet and establish an account with Google to use it. BSA Calculator is a body surface area (BSA) calculator with a simple layout in font that the visually challenged like me can read without squinting.

The large font may also be helpful to the busy physician using an iPhone.

Physicians regularly use body surface area to calculate drug doses for their patients. Notably, the dosing of chemotherapeutic drugs like Cisplatin is determined according to BSA. I use it to control my diet. When my BSA climbs over 2.1 m2, it is high time for me to act.

Estimating human body surface is not trivial. It is difficult to develop one formula that fits all, simply because we come in a wide range of shapes and sizes and the relationship between body height and body weight changes considerably while we grow up. Medcalc provides a handful of methods and references. The suggested formulas have been empirically derived from measurements of height and weight. J.D. Current, 1998, and Than Vu, 1999, critically review the methods in use. Boyd, 1935, published one method that is still widely employed. In recent years the method of Mosteller, 1987, has gained popularity. Both are available in BSAcalc.

  • Boyd E (1935) The growth of the surface area of the human body. University of Minnesota Press, Minneapolis.
  • Mosteller RD (1987) Simplified Calculation of Body Surface Area. New England Journal of Medicine 317: 1098.
The BSA calculator accepts only metric dimensions (Système International). You may use the converter below to convert body height and weight from inches and pounds to centimeters and kilograms, respectively. Enter the body height in inches in the inches box and click on the centimeter box. In analogy, enter the body weight in lbs into the pound box and click on the kilo box:

[in] :
[kg] :

 Converter © You may donate for further development through PayPalhere.
Proceed to the BSA calculator.

  • A authoritative study by Sacks and others (2009) in the New England Journal of Medicine (360:859-873) demonstrates that we can diminish our weight on reduced-calorie diets (02/26/09).

Thursday, July 10, 2008

Who Owns Your Site?

Recently, a friend of mine was pondering some existential questions about websites. She had started an own business selling customized arts and crafts over the internet. She found an appealing name for her site. She tells us on the site, how her real business grew from an unreal idea. The site offers to customers options to create the product they like to purchase. Sales have been taking off. The business shows all signs of success.

My friend is not a web expert and outsourced site development and administration.  Now, questions arise about the ownership of the site. The details of site registration have fundamental implications for ownership, particularly when the site name is synonymous with the brand and the businesses vitally depends on brand recognition. The person who registers the domain name of the site with the registrar may actually own that name. This person may also own the administrative privileges to add and delete data and permit other parties access to site administration. The administrator can potentially read the e-mails on the site.

For those who are not savvy in the use of the terminal command line, I found an easy way to obtain information about your site. Go to Broadband Report's whois browser application, type in your domain name, that is the site name without "www.",  and hit return. Check carefully that the entries match your expectations.

Small Business Tip #1. Click here.

Wednesday, July 2, 2008

How to Build a Silent PC: Episode II

In episode I, I narrated my first experience with building a personal desktop computer, describing important discoveries I made in the process. Earlier this year I build my second PC. Below I shall summarize the essential lessons I learned.

The purpose of this project was to provide my son with a powerful computer to use for his graphics and arts work as well as his games. My son is learning animation with Maya Learning Edition and chess with Chessmaster.This computer would be stationed in his room. The first machine I built boasts 7 fans. The noise these fans collectively produce is considerable. You would not want to have them in your bedroom. Therefore, I was looking for a very quiet design.

On my search for the noiseless machine, I happened on cases for home theater personal computers (HTPC). Computers for the control of high fidelity entertainment centers must be designed noiseless. Compared with standard cases, the fans in these cases commonly run very quietly. As a drawback, I did not find a case with a small form factor. Even the cases, that can house micro-sized (mATX) motherboards, are not much smaller than mid-size towers. At the high end of the price range I are the impressive cases by Zalman. I opted for Antec's Fusion V2, which is comparatively low in price.

Owing to my good experience with Micro-Star International and Advanced Micro Devices, I chose the K9MM-V motherboard and an Athlon 64 3500+ Socket AM2 central processing unit (SKU:CP2-AM2-3500 AV). I purchased both in a bundle for a bargain price from TigerDirect. The "V"s are important. They indicate that board and processor are designed to fully support virtualization. Microsoft's Hyper-V virtualization software is under development and can be tested with a compatibility check utility that AMD provides for download. I opted for Microsoft's Windows XP Professional x64 as operating system to let my son run his applications smoothly and perhaps will use Xen for virtualization.

In my first assembly, I had the CPU pre-installed. This time, I mounted it myself, before placing the board in the case. It was straight forward. A close check of the instructions in the MSI manual sufficed. You must ground yourself, before you start! The designated corner of the CPU and has to match up with that of socket on the board. When the chip is properly aligned, the pins slip smoothly into the holes of the socket. No force is needed. The chip is fastened by pushing down a lever. Then, I applied an even layer of thermal grease and mounted Ultraproduct'son top. The fan has a diameter of 92 mm and provides air flow at 53.5 CFM. The motherboard was ready to be placed in the case.

Next, I filled the the board's memory slots with a pair of PNY 1GB memory modules MD2048KD2-667.
Before you order the memory modules, validate the specifications with the recommendations on the manufacturer's site.

The case came with a 430-W power supply with all necessary connectors attached and provided two internal and one external drive bay. I loaded one internal bay with a Seagate SATA hard drive. I used a Barracuda 7200.10 320GB drive.

The SATA cable came with the motherboard. The board features a second SATA input. I may install another SATA drive in the empty bay. The external drive bay was reserved for the DVD/CD drive. I installed Mad Dog's multimedia IDE drive and connected it to the motherboard with the round cable included in the MSI kit.

Micro-ATX motherboards are about 2" shorter than the regular ATX boards, but still accommodate standard PCI and AGP cards. This was important to me, because I had PCI cards in stock and wanted to be able to use AGP graphics cards. I swapped out the ATI Radeon 9600 PRO card used in my first project for a 9800 series card and installed the old card in this computer. The reason was an important discovery. If you use a mATX motherboard, ensure that the graphics card you intend to use matches the shorter length of this board. The ATI Radeon 9600 card was sufficiently short.

The motherboard accommodated all connections from the case, except the firewire port. Therefore, one of the three PCI slots had to be reserved for a USB/firewire card. I purchased Ultra 8 Port USB 2.0/Firewire PCI Combo Card.
Another slot was taken by a wireless network adapter card. I chose Cisco's Linksys WMP54G PCI Wireless Adapter v41.The Linksys software does not function properly with Windows XP x64. A compatible driver for the card can found at Ralink support. The driver that matched my card can be downloaded at PCI/mPCI/CB(RT256x/RT266x). After insertion of the PCI card, restart the computer and the hardware wizard will announce that new hardware was detected and prompt you for a driver. At this juncture, the wizard has to be manually pointed to the RT61 file in the Ralink folder under program files (x64). If the wizard does not prompt you, the driver can be loaded manually for the network adapter in the device manager. Should Ralink terminate its support for XP, the driver I used is available for download at BMI under downloads.

As useful amenities, I added Gyration's gyrotools.The compact keyboard is light-weight and short. The buttons have a good feel. The optical air mouse doubles as remote control.

You may wish to check out this book, if you seek more advice. I own a few books in this series and found them helpful.
Compusa (Systemax, Inc.)


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