We present an improved analysis of the final dataset from the QUaD experiment .
Using an improved technique to remove ground contamination , we double the effective sky area and hence increase the precision of our CMB power spectrum measurements by \sim 30 \% versus that previously reported .
In addition , we have improved our modeling of the instrument beams and have reduced our absolute calibration uncertainty from 5 % to 3.5 % in temperature .
The robustness of our results is confirmed through extensive jackknife tests and by way of the agreement we find between our two fully independent analysis pipelines .
For the standard 6-parameter \Lambda CDM model , the addition of QUaD data marginally improves the constraints on a number of cosmological parameters over those obtained from the WMAP experiment alone .
The impact of QUaD data is significantly greater for a model extended to include either a running in the scalar spectral index , or a possible tensor component , or both .
Adding both the QUaD data and the results from the ACBAR experiment , the uncertainty in the spectral index running is reduced by \sim 25 \% compared to WMAP alone , while the upper limit on the tensor-to-scalar ratio is reduced from r < 0.48 to r < 0.33 ( 95 % c.l ) .
This is the strongest limit on tensors to date from the CMB alone .
We also use our polarization measurements to place constraints on parity violating interactions to the surface of last scattering , constraining the energy scale of Lorentz violating interactions to < 1.5 \times 10 ^ { -43 } GeV ( 68 % c.l . ) .
Finally , we place a robust upper limit on the strength of the lensing B -mode signal .
Assuming a single flat band power between \ell = 200 and \ell = 2000 , we constrain the amplitude of B -modes to be < 0.57 \mu { K } ^ { 2 } ( 95 % c.l .
) .