Natural α-tocopherol is the RRR-α (or ddd-α) form. The synthetic dl,dl,dl-α ("dl-α") form is not so active as the natural ddd-α ("d-α") tocopherol form. This is mainly due to reduced vitamin activity of the four possible stereoisomers that are represented by the l or S enantiomer at the first stereocenter (an S or l configuration between the chromanol ring and the tail, i.e., the SRR, SRS, SSR, and SSS stereoisomers). The three unnatural "2R" stereoisomers with natural R configuration at this 2' stereocenter, but S at one of the other centers in the tail (i.e., RSR, RRS, RSS), appear to retain substantial RRR vitamin activity, because they are recognized by the alpha-tocopherol transport protein, and thus maintained in the plasma, where the other four stereoisomers (SRR, SRS, SSR, and SSS) are not. Thus, the synthetic all-rac-α-tocopherol, in theory, would have approximately half the vitamin activity of RRR-α-tocopherol in humans. Experimentally, the ratio of activities of the 8 stereoisomer racemic mixture to the natural vitamin, is 1 to 1.36 in the rat pregnancy model (suggesting a measured activity ratio of 1/1.36 = 74% of natural, for the 8-isomer racemic mix).
ATTENTION: If you are updating a world with HexWool from an older version to Minecraft 1.7, you need to first update to 0.3.4 and load the world once. Ignore any ID mismatch warnings on load, that's supposed to happen.
This lists the first six lines of each of the variables in the dataframe as a table. You can similarly retrieve the last six lines of a dataframe by an identical call to the function tail(). Of course, this works better when you have fewer than 10 or so variables (columns); for larger data sets, things can get a little messy. If you want more or fewer rows in your head or tail, tell R how many rows it is you want by adding this information to your function call. Try typing:
EDIT: Some more information on the "treatment". Each treatment is the introduction of a new regulation. Each individual is treated based on how much he spends in a given year. If he spends more, his intensity of treatment (i.e., exposure to the regulatory shock) is higher, if he spends less, his intensity of treatment (i.e., exposure to the regulatory shock) is less, CT is bounded between 0 and 1. The first regulation occurred before the start of the sample period in 1992. This affected ALL individuals at the same time, but then after 1992, for each individual, a "newer" version of the regulation came into effect, but introduction is staggered for each individual. The difference between the "newer" regulation and the initial one in 1992 is that the amount of money one spends translates into a different amount of treatment intensity. E.g., if someone spends $1 under the 1992 regulation, then the treatment intensity, say, takes a value of 0.1, but under the newer regulation, \$1 may translate into only 0.01 (these are just hypothetical values I made up to illustrate the difference in the regulation). Let me explain in detail how CT varies for each individual:
Alternatively, if you have a header row, but it is not on the firstline of your file, you can use tail -n + to have clipivot read everything but the nth row. For instance, if the header row of your CSV file bad_csv.csv is on the fifth line, you can type 781b155fdc