Cut-off designs

In the cut-off trial there are then three regions for allocation. If the middle randomized region is eliminated so that the two outer regions meet, we then have the extreme example of a cut-off design, the regression discontinuity design. In analysing the cut-off... 

Mild hypertension Moderate hypertension Severe hypertension Figure 6.3 Schematic representation of a cut-off design. 

A further problem with cut-off designs is that they preclude any serious attempt at blinding treatment. Without the unpredictability of allocation which randomization provides, there can be no truly blinded trial. This in turn makes employment of a placebo also impossible, or at least futile. If anything, the ethical problems of using placebos would be even greater than for a run-in. One could hardly claim that it was... 

Figure 6.4 Variance of a symmetric cut-off design as a function of the randomized proportion of patients.

In order to compare the efficiency of the designs (as opposed to approaches to analysis) we assume that the same analysis, namely analysis of covariance, will be used in all three cases. For the cut-off designs we shall assume that we are allocating treatment on the basis of an observed baseline, and for the minimized design that we are using some allocation mechanism which reduces the disparity in this baseline. (See also Chapter 7 for discussion of efficiency and analysis of covariance.)... 

For a=0, which corresponds to the extreme case of a cut-off design in which no patients are randomized (the regression discontinuity design), E[A2 2.75. For a = oo we have a completely randomized design and A2 1. 

A covariance study by Li et al. [76] dealt with the comparison of various sampling schemes and accumulation profiles with respect to their usability with covariance processing. The authors divided sparse sampling schemes into the non-uniform and the ti cut-off (CUO) schemes. While common NUS schemes employ—exponentially—increasing A(i spacing as a function of (i, a cut-off design implies the sole acquisition of signals at short <1 times up to a maximum value. The 2D NMR spectrum is then reconstructed with appropriate methods. Various standard, NUS and... 

The part stress analysis prediction section contains failure rate models for a broad variety of parts used in electronic equipment. This method includes the effects of part quality factors and environmental factors. The tabulated values of the base failure rate are "cut off" at the design temperature and stress of the part. 

The filter system designed will filter all frequencies lying above the cut-off frequency of 6.95 cycles/sec to the first band-pass of 35.8 2 cycles/sec, and the second band-pass of 70.5 2 cycles/sec. This arrangement should perform satisfactorily. 

From Fig. 4-84 determine that (for a line with a design factor of 5) the first cutoff would be made after 1200 ton-miles and additional cut-offs after each successive 1000 ton-miles. 

The chemical and petrochemical industries are highly capital intensive and this has two important implications for the plant designer. Before the expenditure for any plant is approved, a discounted cash flow (DCF) return on capital invested is projected (Section 9.1). The capital cost of the plant is a key factor in deciding whether the DCF return is above or below the cut-off value used by a company to judge the viability of projects. Thus, there is always strong pressure on the materials engineer not to overspecify the materials of construction. 

Benchmarq Microelectronics, Inc., designed a special (more expensive) charging chip for RAM cells, connected in series [40]. The advantage is a complete disconnection of the load when the first cell reaches the predetermined cut-off voltage. Cell reversal is thereby eliminated. 

Many other filter functions can be designed, e.g. an exponential or a trapezoidal function, or a band pass filter. As a rule exponential and trapezoidal filters perform better than cut-off filters, because an abrupt truncation of the Fourier coefficients may introduce artifacts, such as the annoying appearance of periodicities on the signal. The problem of choosing filter shapes is discussed in more detail by Lam and Isenhour [11] with references to a more thorough mathematical treatment of the subject. The expression for a band-pass filter is H v) = 1 for v j < v < else... 

Figure 3.13 Three methods of chemically etching metal tips for STM. In (a) the current cut-off is manually or electronically triggered when the end of the etched wire falls the finite time delay inherent in this approach results in a blunting of the final tip as etching continues after separation, (b) This shows an adaptation in which the etching current is automatically cut off when the lower portion of the wire drops - it is the lower portion that is used as an STM tip. (c) This shows an improved design in which the etching current is fed to the lower portion of the tungsten wire through an electrolyte held in a conductive beaker. In this case the upper portion of the etched wire is kept.

The very low storage temperature and low operating temperature specifications (see Section 4.3 below) also required dedicated design features because many of the components, such as the pumps and processors, cannot operate at very low temperatures. Because of this limitation there were added to several components cold start heaters controlled by snap switches. Further, an industrial temperature grade microprocessor was used in the SDU. With the snap switches the cold start heaters can come on when the power is applied at less than about 32°F/0°C. The snap switches cut off the cold start heaters and apply power to the full CBMS II system once their setpoint temperature is reached. 

PCF calculation Software Simapro software was used to design process tree, and calculate PCF, based on the impact method GWP 100 years. Cut-off on processes impact is set to 1% to ease results view... 

A recent cartridging machine is the Rollex, designed by the firm of Niepmann Sons. This operates on an entirely different principle in that the explosive is first rolled into a sheet and then portions of this sheet are cut off and automatically wrapped in paper. It can also be used for cartridging semi-gelatine explosives. 

Due to issues of polarization in a specific cell design we use for testing, the cut-off potential at C/2 is fixed at - 40mV vs Li/Li+. At this negative potential we never observed with LBG material any lithium plating. 

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