Wednesday, August 29, 2012

How to Overlining Words in Microsoft Word

Tips: Windows

Tuesday, August 28, 2012

Fifty Shades of Brown

Fifty Shades of Brown: The Evolving View of Fat
Source: Circulation

This is an editorial article of a PVAT (Perivascular adipose tissue) study supports fat is friend not foe. I have learned decades ago in my medical school that the BAT (brown adipose tissue) which is major thermogenetic fat for an infant, especially cold area of world without heat. Now, researchers find that adults also have the BAT a little bit here and a little bit there.

"...
The relationship between increased body mass index and risk for diabetes mellitus or cardiovascular disease is well established. Such observations have driven considerable interest into the nature of adipose tissue and what mechanisms might help explain how adipose tissue and specific aspects of adipocyte biology influence cardiometabolic disorders. For example, adipocytes are now recognized as a source of mediators released into the circulation, like the adipokines resistin and adiponectin, which can modulate inflammation, insulin sensitivity, and atherosclerosis. Other molecules released from adipocytes like free fatty acids and reactive oxygen species can also exert both local and distant effects that may be integral to the development of diabetes mellitus, atherosclerosis, and their complications. To an increasing extent, adipose tissue is now understood as an organ playing important physiological and pathological roles. Both the absence of fat, as with certain lipodystrophies, and excess adiposity are associated with diabetes mellitus, with mechanisms that appear to include infiltration of inflammatory cells into adipose tissue and the release of systemic mediators.
..."

Wednesday, August 08, 2012

How to calculate confidence interval of incidence rate under the Poisson distribution


How to calculate the confidence  interval of incidence rate under the Poisson distribution


Incidence rate (IR) = # event (N) / person-time at risk (T)

The exact Poisson confidence interval (CI) (Ulm, 1990): 
                   (1- α) % CI of N =
                   (1- α) % CI of IR


If is large, 95% CI of N
                    95% CI of IR =  = 

You may use PQRS or use an online calculate like GraphPad QuickCalcs, or Quantile Function Calculator to get a quantile of the chi-square distribution.


The Online OpenEpi, a nice Epidemiologic Calculator, provides different ways to get these confidence intervals. I noticed, if N = 0, the calculator gives N = 0.5 to avoid unrealistic results.


Stata can give exact Poisson CI:
     .cii T N, poisson

Wednesday, August 01, 2012

Recipes

Recipes