Methods and apparatus for the processing of digital signals having high speed and low power dissipation. The apparatus uses Residue Number Systems (RNSs) to represent the signals and/or parameters, with each digit within an RNS system being encoded in a "one-hot" encoding scheme wherein each possible value of a digit has an associated single line, one and only one of which will be high at any one time. The combination of an RNS system with the one-hot scheme results in low signal activity and low loading of signal lines which in turn result in low power. Methods and apparatus for addition, subtraction, multiplication and other operations, and conversion from and to natural numbers. The speed advantage offered by other RNS-based architectures is retained.

1. Field of the Invention
The present invention relates to methods and apparatus for the processing of digital signals.
2. Prior Art
Various architectures of digital signal processing circuitry such as digital filters and the like are well known in the art. Most of these architectures use a conventional binary numbering system to represent the parameters and the signals. Some architectures, though, use a Residue Number System (RNS) to represent both the parameters and the signals. An RNS representation has the advantage that the operations of multiplication, addition and subtraction--the basic operations in filtering, signal detection and the like--are exceedingly fast because, in contrast to a binary numbering system, no carries between digits are necessary to perform the operations. It has been reported in the literature that this speed advantage is the sole advantage of using an RNS system over using a conventional system of numbering.
In an RNS representation of a number X, the number is represented by a number of digits wherein each digit has its own limited range as follows: EQU X=x.sub.ma,x.sub.mb, . . . ,x.sub.mN
where:
X=a natural number
x.sub.ma, x.sub.mb, . . . x.sub.mN are each a digit in the RNS representation of the natural number X wherein:
x.sub.ma =X mod(m.sub.a)=the remainder after X is divided by m.sub.a. The remainder is therefore less than m.sub.a. PA1 x.sub.mb =X mod(m.sub.b), etc., and PA1 m.sub.a, m.sub.b . . . m.sub.N are the different moduli (integer numbers), each associated with a respective digit in the RNS representation of the natural number X. PA1 where: m=the modulus of the digit, a positive integer PA1 1.) X is evenly divisible by the integer divisor d (remainder=0). Then X/d is clearly an integer number, and expressible in RNS form in the same RNS system as X. PA1 2.) The divisor and the modulus of the RNS digit are relatively prime. PA1 where: PA1 N.sub.d =the integer value of (X/d)/m=(N-n)/d PA1 x.sub.d =(x+n*m)/d=the value of the RNS digit in the RNS representation of X/d PA1 x.sub.d can also be found directly by using RNS multiplication of x by a number called the multiplicative inverse of d, as follows: Since (x+n*m)/d=x.sub.d : EQU x+n*m=x.sub.d *d PA1 then EQU x*I.sub.dm mod(m)=xd mod(m)=x.sub.d PA1 I.sub.dm, then, is the multiplicative inverse of d in the modulus m. If d is relatively prime with respect to m the multiplicative inverse exists (without proof herein), hereinafter denoted d.sub.m.sup.-1. PA1 where a.sub.1, a.sub.2, etc. are functions of x.sub.1, x.sub.2, etc. PA1 where x.sub.2 ' is the value of the second RNS digit after the subtraction of a.sub.1 and the division by m.sub.1. PA1 Pos/Neg, M even: -M/2<=X<=M/2-1 PA1 Pos/Neg, M odd: -(M-1)/2<=X<=(M-1)/2
If the moduli are relatively prime, that is, the smallest single number into which all will divide evenly is equal to the product of all the moduli, then the range of numbers that can be uniquely represented in any particular RNS form X=x.sub.ma,x.sub.mb, . . . ,x.sub.mN is m.sub.a *m.sub.b * . . . *m.sub.N. This excludes the possibility of repetition of a modulus, but not even numbers or a perfect square. For instance note that 3, 4 and 5 are relatively prime in that the smallest single number into which all will divide evenly is 60, even though 4 is both an even number and a perfect square.
As an example of the foregoing, consider the example of a Residue Number System shown in Table 1. In this RNS, each integer is represented by three RNS digits x.sub.3, x.sub.5 and x.sub.7, the subscript of each digit being the value of the associated modulus. Thus this is a 3, 5, 7 RNS, being able to distinguish 3*5*7=105 unique integers. As can be seen from Table 1, no RNS representation repeat in the range from 0 to 104, though the entire sequence begins to repeat again if one tries to extend the same to 105 and beyond.
TABLE 1 ______________________________________ Natural RNS RNS RNS Number digit digit digit X x.sub.3 x.sub.5 x.sub.7 ______________________________________ 105 0 0 0 104 2 4 6 . . . . . . . . . . . . 15 0 0 1 14 2 4 0 13 1 3 6 12 0 2 5 11 2 1 4 10 1 0 3 9 0 4 2 8 2 3 1 7 1 2 0 6 0 1 6 5 2 0 5 4 1 4 4 3 0 3 3 2 2 2 2 1 1 1 1 0 0 0 0 ______________________________________
As an example of how the RNS system works, consider the natural number 14. The x.sub.3 digit is 14 mod(3)=the remainder 2, i.e. 14/3=4 remainder 2. The x.sub.5 digit is 14 mod(5)=the remainder 4, i.e. 14/5=2 remainder 4. The x.sub.7 digit is 14 mod(7)=the remainder 0 (14/7=2 remainder 0). It will be noted that each digit is determined without reference to any other digit in the RNS representation.
Also note that the same 3,5,7 RNS representation might be used to uniquely represent the numbers 105 to 209. However addition, subtraction and multiplication of any two numbers in the range of 105 to 209 all provide a result which is out of the range of 105 to 209, making this scheme rather useless for digital signal processing. Of particular interest for digital signal processing however, is the introduction of negative numbers by limiting the range of numbers representable in the RNS system chosen to an equal or substantially equal number of positive and negative numbers, as most signals processed will have or can be made to have a substantially zero average value. Such an assignment for a 3,5,7 RNS system is shown in Table 2. Again note that 105 numbers -52 to +52 are uniquely represented in the RNS, but the representations begin to repeat at 53 and -53. Note also that no separate sign is associated with positive or negative RNS numbers, but instead the sign is determined by the digits themselves once the RNS system and its range is selected. Finally, note that even the sign of the associated natural number represented in RNS form cannot be determined from any less than all the RNS digits in the RNS representation of the number.
TABLE 2 ______________________________________ Natural RNS RNS RNS Number digit digit digit X x.sub.3 x.sub.5 x.sub.7 ______________________________________ 53 2 3 4 52 1 2 3 . . . . . . . . . . . . 15 0 0 1 14 2 4 0 13 1 3 6 12 0 2 5 11 2 1 4 10 1 0 3 9 0 4 2 8 2 3 1 7 1 2 0 6 0 1 6 5 2 0 5 4 1 4 4 3 0 3 3 2 2 2 2 1 1 1 1 0 0 0 0 -1 2 4 6 -2 1 3 5 -3 0 2 4 -4 2 1 3 -5 1 0 2 -6 0 4 1 -7 2 3 0 -8 1 2 6 -9 0 1 5 -10 2 0 4 -11 1 4 3 -12 0 3 2 -13 2 2 1 -14 1 1 0 -15 0 0 6 . . . . . . . . . . . . -52 2 3 4 -53 1 2 3 ______________________________________
For RNS addition, each respective pair of digits of the two RNS numbers are added and the applicable modulo operation is performed on each respective sum.
Example ##EQU1##
But 3 mod(3)=0 and 7 mod(5)=2. Therefore the sum 375 in the RNS system is 025, representing the natural number 12 (see Table 2).
For subtraction, the same procedure is followed, though the modulus may have to be added back to bring the "remainder" into the range of 0 to the respective modulus minus 1.
Example ##EQU2##
But adding the applicable modulus of 7 to -5 gives a "remainder" of 2. Therefore plus 13 subtracted from plus 8 in this RNS system is 102, representing the natural number -5 (see Table 2).
For addition involving a negative number, the same procedure is followed as in addition of positive numbers.
Example ##EQU3##
But 4 mod(3) is 1 and 5 mod(5) is 0. Therefore -13 added to 8 in this RNS system is 102, again representing the natural number -5 (see Table 2).
Finally, in the case of multiplication, consider the following example:
Example ##EQU4##
But 12 mod(7) is 5. Therefore (-3)*(-4) in this RNS system is 025, again representing the natural number 12 (see Table 2).
It can be seen that addition, subtraction and multiplication of positive and negative numbers expressed in a RNS form work in the RNS system. The key observation to be made, though, is that the operations are performed on each RNS digit independently, without reference to results of the same operation on any other RNS digit. The high speed characteristic of RNS arithmetic is due to this "carry free" nature of the operations, whereas in conventional arithmetic, the results of multiplication, addition or subtraction of a particular digit cannot be finally determined until the results of the operation on less significant digits have been determined.
Division is also possible in an RNS system, with certain essential limitations. The principles of division in an RNS system may be illustrated as follows. In a single digit x of an RNS representation of a natural number X: EQU X=m*N+x
N=an integer (which will be a negative integer for negative numbers) PA2 x=the value of the RNS digit (the remainder, in the range of 0.ltoreq.x.ltoreq.m-1, after subtracting m*N from X)
For any individual RNS digit, only x, the value of the digit itself, is known. Knowledge of only a single digit does not give knowledge of X, or N for that digit.
The above equation for X may be written in various ways as follows: ##EQU5## where: n=is an arbitrary positive integer
The operation of division can occur on an RNS digit by RNS digit basis provided the following two conditions are met (the satisfaction of these two conditions will be commented on hereafter on a case by case basis):
Using the above equations for X, X/d may be expressed in a conventional number system by any of the following equations: ##EQU6##
If there is a value of n where (x+n*m)/d is an integer, then because X/d is also an integer, m*(N-n)/d is an integer. Therefore, m*(N-n) must include a factor d. Since it is assumed that m is relatively prime with respect to d, (N-n) must include the factor d, and so (N-n)/d is also an integer.
Furthermore, if for one and only one value of n, (x+n*m)/d is an integer in the range of 0 to m-1, then X/d=m*(N-n)/d+(x+n*m)/d is in the form of the equation: EQU X/d=m*N.sub.d +x.sub.d
If m and d are relatively prime, it is stated without proof will be one and only one value of n for which (x+n integer in the range of 0 to m-1.
By way of example, consider a digit of modulus 5 of an RNS representation of a number X evenly divisible by d. First consider 56 divided by 7=8. The modulus 5 RNS digit x of 56 is 1 and the modulus 5 RNS digit x.sub.d of 8 is 3. Therefore x=1 and x.sub.d should come out out to be 3. Though not known from x, N=the integer value of 56/5=11. The possibilities for x.sub.d =(x+n*m)/d in the range of 0 to 4 for various values of n, and for N.sub.d =(N-n)/d are shown in Table 3 below.
TABLE 3 ______________________________________ X.sub.d (x + n*m) (x + n*m)/d N.sub.d (x + n*m)/d = n (x = 1) (d = 7) (N - n)/d an integer ______________________________________ 0 1 1/7 11/7 1 6 6/7 10/7 2 11 11/7 9/7 3 16 16/7 8/7 4 21 21/7 = 3 7/7 = 1 3 ______________________________________
While the foregoing only illustrates the division of 56 by 7, the second and third columns of Table 3 are the same for any number X evenly divisible by 7 and having an RNS digit of modulus 5 equal to 1. Thus in any RNS system in which one of the RNS digits has a modulus of 5, when that RNS digit has a value of 1 in the RNS representation of a number X evenly divisible by 7, the corresponding digit in the RNS representation of the result of dividing X by 7 will always be 3. The same procedure may be used to find the respective value of the RNS digit of modulus 5 in X/7 when the corresponding RNS digit in X has any of the other values 0, 2, 3 and 4 (x.sub.d =0, 1, 4 and 2, respectively).
This same technique, of course, can readily be further extended to division in general wherein the divisor and the modulus of the digit are relatively prime and it is known that X/d is an integer. It also works for negative numbers. For instance, consider -49 divided by 7. For -49, an RNS digit of modulus 5 is also 1. Therefore, as before, the RNS digit of modulus 5 in the RNS representation of the result will be 3, which is the RNS digit of modulus 5 in the RNS representation of -7.
Multiplying both sides of the above equation by some integer I.sub.dm : EQU x*I.sub.dm +n*m*I.sub.dm =x.sub.d *d*I.sub.dm
Then taking mod(m) of both sides gives: EQU (x*I.sub.dm +n*m*I.sub.dm)mod(m)=(x.sub.d *d*I.sub.dm)mod(m)
The term n*m*I.sub.dm on the left of the above equation can be dropped since it is an integer multiple of the modulus m, and an additional mod(m) operation can be inserted on the right without changing the result. Thus: EQU x*I.sub.dm mod(m)=[x.sub.d *(d*I.sub.dm mod(m))] mod(m)
If an integer Idm can be found such that EQU d*I.sub.dm mod(m)=1
To find the multiplicative inverse d.sub.m.sup.-1 of d for the modulus m, it is not necessary to search through all integers for the integer d.sub.m.sup.-1 such that: EQU d*d.sub.m.sup.-1 mod(m)=1
If d.sub.m.sup.-1 exists, then it is also true that EQU [d*(d.sub.m.sup.-1 mod(m))] mod(m)=1
Given d mod(m) then, it is only necessary to search from 1 through m-1 to find the inverse of d in the modulus m (the inverse cannot be 0).
Note that if d mod(m)=0, then no multiplicative inverse will be found. Of course, if d mod(m)=0, then d and m are not relatively prime and one of the two conditions for division has not been satisfied.
Thus rather than dividing by a number, such as a number d, one can multiply by d.sub.m.sup.-1, the multiplicative inverse of d. To illustrate a multiplicative inverse, consider division by 13 for a modulo 5 digit of an RNS number. The digit may have values of 0, 1, 2, 3 or 4. Using the first approach to division described to divide by 13, the modulus 5 may be repeatedly added to the RNS digit value until the sum is evenly divisible by 13. In that regard, there will be only one such number evenly divisible by 13 to give a result of 0, 1, 2, 3 or 4, as shown in Table 4 below.
TABLE 4 ______________________________________ x + n*m x.sub.d Value x Value of the of the modulo Value of the Add modulus modulo 5 5 digit modulo 5 5 "n" times digit divided by digit n= plus n*5 13 ______________________________________ 0 0 0 0 1 5 26 2 2 10 52 4 3 2 13 1 4 7 39 3 ______________________________________
However, multiplying the value of the modulo 5 digit times 2 gives an identical result. Thus for the modulo 5 digit, dividing by 13 is identical to multiplying by 2. Using the equation: EQU d.sub.m.sup.-1 *d mod(m)=1 EQU .sub.5.sup.-1 *13 mod(5)=1 EQU or again, 13.sub.5.sup.-1 =2
While the operations of addition, subtraction and multiplication are carry free in an RNS system and hence simple and fast to execute, other operations that are simple and fast in a binary numbering system are cumbersome within an RNS system. For example, truncation in a binary system is simply the dropping of the least significant digits of the number to be truncated. In an RNS system, the digits do not have a relative significance, and therefore truncation is problematic.
Other operations that are difficult in an RNS number system include division, scaling (division by a fixed factor), sign detection, comparison, and dynamic range extension. As these are simple operations in binary, it is in principle possible to convert from an RNS number form to binary, perform the operation on the binary number, and then reconvert to an RNS number form if necessary (comparison and sign detection are results in themselves, and the RNS number or numbers on which they have operated may be preserved in RNS form for later use). However the Associated Mixed Radix (AMR) representation of a number can be found more naturally than the binary representation from the RNS representation.
Like a binary or decimal number, a mixed radix number is expressed by digits that have a relative significance. But unlike binary and decimal numbers, the weight of each digit is not a fixed multiple ("radix") of the weight of the immediately less significant digit.
The radix of a decimal number is 10. The value of the least significant digit ranges from 0 to 9. The next most significant digit, which also varies from 0 to 9, has a weight of 10. The next most significant digit has a weight of 100, 10 times larger than the weight of the previous digit, etc. The radix of a binary number is 2. The value of the least significant binary digit ranges from 0 to 1. The next most significant binary digit, which also varies from 0 to 1, has a weight of 2. The next most significant digit has a weight of 4, 2 times larger than the weight of the previous digit, etc.
The radix of a mixed radix number changes from digit to digit. Considering first only positive numbers, the value of the least significant digit ranges from 0 to p-1. The weight of the next most significant digit is "p". The value of this digit, though, ranges from 0 to q-1, where "q" in general is not equal to "p". The weight of the next digit is "q" times the weight of this digit, namely "p" times "q", and its value can range from 0 to yet 20 a different maximum.
Of interest here is when the radices of a mixed radix representation of an integer X are equal to the moduli m.sub.1, m.sub.2, etc. of the RNS representation of the integer X (hence the "Associated" Mixed Radix representation). The value of the least significant digit ranges from 0 to m.sub.1 -1, where m.sub.1 is one of the RNS moduli. (Note that in the following discussion, the notation style has changed. Subscripts no longer indicate the value of the modulus, but rather merely distinguish between RNS system digits.) The next AMR digit, which has a weight of m.sub.1, ranges from 0 to m.sub.2 -1, etc. The natural number X, then, in AMR form can be expressed as EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *(m.sub.1 *m.sub.2)+a.sub.4 *(m.sub.1 *m.sub.2 *m.sub.3)+ . . .
where a.sub.1, a.sub.2, etc. are the AMR digit values. Note that the range under the AMR representation is identical to the range of the corresponding RNS representation of a number X. For instance, assume four AMR digits a.sub.1, a.sub.2, a.sub.3 and a.sub.4. Then X can range from zero to: EQU X.sub.max =(m.sub.1 -1)+(m.sub.2 -1)*m.sub.1 +(m.sub.3 -1)(m.sub.1 *m.sub.2)+(m.sub.4 -1)*(m.sub.1 *m.sub.2 *m.sub.3)=m.sub.1 *m.sub.2 *m.sub.3 *m.sub.4 -1
The values for the AMR digits a.sub.1, a.sub.2, etc. can be obtained from the RNS representation of X using the following methodology.
Consider a natural number X having the RNS representation x.sub.1,x.sub.2, . . . ,x.sub.N in the moduli m.sub.1, m.sub.2, . . . , m.sub.N. Again X can be expressed as: EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *m.sub.1 *m.sub.2 + . . . +a.sub.N *m.sub.1 *m.sub.2 * . . . *m.sub.N-1
By taking modulo m.sub.1 of each side of the above equation: EQU X mod(m.sub.1)=(a.sub.1 +a.sub.2 *m.sub.1 + . . . a.sub.N *m.sub.1 * . . . *m.sub.N-1) mod(m.sub.1)
The left side of the above equation is simply equal to x.sub.1. Note that m.sub.1 is a factor in every term on the right side of the equation except the first, and therefore all terms except the first can be dropped. Therefore: EQU x.sub.1 =a.sub.1 mod(m.sub.1)=a.sub.1
Now subtract a.sub.1 from X using RNS subtraction and divide the result by m.sub.1 using RNS division to obtain the result X' in RNS form. EQU X'=(X-a.sub.1)/m.sub.1 =a.sub.2 +a.sub.3 *m.sub.2 + . . . +a.sub.N *m.sub.2 * . . . *m.sub.N-1
Note that subtracting a.sub.1 from X drives the value of the x.sub.1 digit of the RNS representation of X to zero, meaning that the result X-a.sub.1 is evenly divisible by m.sub.1, so that X' is an integer representable in RNS form. Also note that the divisor m.sub.1 is relatively prime to all of the moduli except itself. Therefore, the two conditions for valid RNS division have been satisfied for all RNS digits except the first. Fortunately, the inability to legitimately divide the first digit is of no consequence, as the possible range of the result is diminished so as to be uniquely expressible by the remaining digits.
Now taking mod(m.sub.2) of X': EQU X' mod(m.sub.2)=(a.sub.2 +a.sub.3 *m.sub.2 + . . . +a.sub.N *m.sub.2 * . . . * m.sub.N-1) mod(m.sub.2)
Consequently: EQU x.sub.2 '=a.sub.2 mod(m.sub.2)=a.sub.2
Repeating the process as required: EQU a.sub.1 =x.sub.1, a.sub.2 =x.sub.2 ', a.sub.3 =x.sub.3 ", etc.
As an example of the foregoing, consider the natural number 41 in the 3,5,7 RNS system of Table 1. The natural number 41 is 216 in RNS. Thus: EQU X=216 RNS EQU x.sub.1 =a.sub.1 =2 EQU X-a.sub.1 =X-2=044 RNS EQU X'=(X-a.sub.1)/3=36 RNS (3.sub.5.sup.-1 =2, 3.sub.7.sup.-1 =5) EQU x.sub.2 '=a.sub.2 =3 EQU X'-3=03 RNS EQU X"=(X'-3)/5=2 RNS=x.sub.3 "=a.sub.3 (5.sub.7.sup.-1 =3)
Thus a.sub.1 =2, a.sub.2 =3 and a.sub.3 =2.
As a check: EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *m.sub.1 *m.sub.2 EQU X=2+3*3+2*3*5=2+9+30=41
Now consider the Associated Mixed Radix representation of positive and negative numbers in the 3,5,7 RNS system of Table 2, wherein the numbers X range from -52 to +52. Again the AMR representation of a number X is: EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *m.sub.1 *m.sub.2
The moduli m.sub.1, m.sub.2 and m.sub.3 are necessarily positive, but the values of a.sub.1, a.sub.2 and a.sub.3 are not so limited, though each is limited in range to the range of the respective one of m.sub.1, m.sub.2 and m.sub.3. Thus if: EQU -1.ltoreq.a.sub.1 .ltoreq.+1 EQU -2.ltoreq.a.sub.2 .ltoreq.+2 EQU -3.ltoreq.a.sub.3 .ltoreq.+3
Then X will range from -1+(-2*3)+(-3*3*5)=-52 to +1+(+2*3)+(+3*3*5)=+52, as in Table 2.
As an example of the foregoing, again consider the natural number 41 in the 3,5,7 RNS system of Table 2. The natural number 41 is 216 in RNS. Thus: EQU X=216 RNS EQU x.sub.1 =a.sub.1 mod(3)=2
Given that x.sub.1 =a.sub.1 mod(3)=2 and -1.ltoreq.a.sub.1 .ltoreq.+1, a.sub.1 must be -1. EQU X-a.sub.1 =X-(-1)=216 RNS+111 RNS=020 RNS EQU X'=(X-a.sub.1)/3=40 RNS EQU x.sub.2 '=4=a.sub.2 mod(5) EQU a.sub.2 =-1 (since -2.ltoreq.a.sub.2 .ltoreq.+2) EQU X'-a.sub.2 =X'-(-1)=40 RNS+11 RNS=01 RNS EQU X"=(X'-a.sub.2)/5=3 RNS EQU x.sub.3 '=3=a.sub.3 mod(7)=a.sub.3
Thus a.sub.1 =-1, a.sub.2 =-1 and a.sub.3 =3.
As a check: EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *m.sub.1 *m.sub.2 EQU X=-1+(-1*3)+3*3*5=-1+(-3)+45=41
In the preceding example including a range of negative numbers, all the moduli were odd (i.e., 3, 5 and 7), and the numbers representable in AMR form ranged from -52 to +52. For another system where the moduli are 2, 5, and 11, a range inclusive of positive and negative numbers could instead be from -55 to +54. More generally, the total range representable in AMR form is equal to M=m1*m2* . . . , the product of the moduli. If only positive numbers ranging from 0 are considered, then 0<=X<=M-1. If inclusive of negative numbers also, there are two possibilities of particular interest. If any one of the moduli is an even number, M will be an even number. Otherwise, M will be an odd number. Two possibilities of range inclusive of both positive and negative numbers can therefore be identified:
The determination of the range of the possible values of the individual AMR digits depends on which of the two possibilities apply. If all moduli are odd, then M is odd and the total range is symmetrical about zero. It is therefore necessary for all the AMR digits to also have ranges symmetric about zero. For all AMR digits "aa" associated with moduli "m", then:
For all AMR digits (M odd): -(m-1)/2<=a<=(m-1)/2 as exemplified above in the 3, 5, 7 system.
If one of the moduli is even and M is therefore even, the range inclusive of both positive and negative numbers is not symmetric about zero and the determination of the range of AMR digit values is more complicated. First, note that there can be only one even modulus. Otherwise, the moduli in the RNS system would not be relatively prime (all even moduli would have a common factor of two). The range of AMR digit values depends on the location, in terms of significance, of the digit associated with the even modulus:
______________________________________ AMR digit associated with -m/2 <= a <= m/2 - 1 the even modulus: AMR digits associated with -(m-1)/2 <= a <= (m-1)/2 odd moduli more significant than the digit associated with the even modulus: AMR digits associated with 0 <= a <= m-1 odd moduli less significant than the digit associated with the even modulus: ______________________________________
To understand this arrangement, note that while the total range with M even is asymmetrical about zero, it is only slightly so, and therefore the most significant digits that can have symmetric ranges need to have such. The even digit needs to have an asymmetric range, and it should be in favor of the negative values but only slightly so. Finally, if the even digit is not the least significant digit, even its slightly asymmetric range will give excessive asymmetry towards negative values in the total range, and the less significant odd digits need to acquire only positive values to compensate.
For example, the 2, 5, 11 RNS system briefly mentioned above could, again, represent the natural numbers from -55 to +54. If the AMR representation is such that the AMR digits, from the most significant to the least significant, are associated with the 11, 2, and 5 moduli respectively, then the digits should have the following ranges: EQU -5<=a3<=+5 EQU -1<=a2<=0 EQU 0<=a1<=+4
As a check, the minimum natural number X representable in AMR form is EQU X.sub.min =0+(-1)*5+(-5)*5*2=0-5-50=-55
and the maximum is EQU X.sub.max= 4+0*5+5*5*2=4+0+50=+54
An AMR representation of a number has various uses, such as to create a new RNS digit for an expanded RNS representation of the number. To create the new RNS digit x.sub.N+1 having modulus m.sub.N+1 : EQU X=a.sub.1 +a.sub.2 *m.sub.1 +a.sub.3 *m.sub.1 *m.sub.2 + . . . +a.sub.N *m.sub.1 *m.sub.2 * . . . *m.sub.N-1 EQU x.sub.N+1 =X mod(m.sub.N+1)=(a.sub.1 + . . . +a.sub.N *m.sub.1 * . . . *m.sub.N-1) mod(m.sub.N+1) EQU x.sub.N+1 =((a.sub.1) mod(m.sub.N+1)+(a.sub.2 *m.sub.1) mod(m.sub.N+1)+ . . . ) mod(m.sub.N+1)
Again as an example, consider the generation of a new RNS digit of modulus 11 for the natural number 41 expressed as the 3,5,7 RNS number 216, first in the all positive RNS representations of Table 1. It has already been determined that a.sub.1 =2, a.sub.2 =3 and a.sub.3 =2. In this case: EQU x.sub.N+1 =((a.sub.1) mod(m.sub.N+1)+(a.sub.2 *m.sub.1) mod(m.sub.N+1)+(a.sub.3 *m.sub.1 *m.sub.2) mod(m.sub.N+1)) mod(m.sub.N+1) EQU x.sub.N+1 =(2 mod(11)+(3*3) mod(11)+(2*3*5) mod(11)) mod(11) EQU x.sub.N+1 =((2)+(9)+(30 mod(11))) mod(11) EQU x.sub.N+1 =(2+9+8) mod(11)=19 mod(11)=8
Obviously this is correct, in that 41 mod(11) is 8. Thus the natural number 41, expressed in a 3,5,7 RNS as 216 RNS, is expressed in a 3,5,7,11 RNS as 2168 RNS. While for the natural number 41 the additional RNS digit is redundant, the range of the natural numbers expressible in the new four digit 3,5,7,11 RNS is eleven times that expressible in the three digit 3,5,7 RNS. Note that it was not necessary to determine the actual value of X=41. x.sub.N+1 was determined solely by the RNS and AMR digits. The foregoing is called "Base Extension".
Now consider the generation of a new RNS digit of modulus 11 for the natural number 41 expressed in the 3,5,7 positive and negative number RNS representations of Table 2. It has already been determined that in the positive and negative number range system, a.sub.1 =-1, a.sub.2 =-1 and a.sub.3 =3. In this case: EQU x.sub.N+1 =((a.sub.1) mod(m.sub.N+1)+(a.sub.2 *m.sub.1) mod(m.sub.N+1)+(a.sub.3 *m.sub.1 *m.sub.2) mod(m.sub.N+1)) mod(m.sub.N+1) EQU x.sub.N+1 =((-1) mod(11)+(-1*3) mod(11)+(3*3*5) mod(11)) mod(11)
Thus: EQU x.sub.N+1 =((10)+(8)+(45) mod(11)) mod(11) EQU x.sub.N+1 =(10+8 +1) mod (11)=19 mod(11)=8
In electronic circuits, various encoding schemes are well known in the representation of digit values. In conventional binary encoding, each digit can be represented by a single signal, or a single "line". A line with a high voltage represents a binary "1". A line with a "low" voltage represents a binary "0". In binary coded decimal, each decimal digit is represented by four lines, and the various voltage levels on the lines determine the value of the decimal digit. Commonly used methods and apparatus for the processing of digital signals use one of these two representations of real numbers, most commonly the binary encoding. Decoding of a digit to a 1 of N form is also common, but not for digital processing, but rather for device addressing and for control purposes.


Provided is a novel active oxygen-resisting agent which has an excellent active oxygen resistance and which exhibits a good solubility in an oil solvent. An active oxygen-resisting agent containing as an active ingredient an amino acid derivative represented by the following formula (I) ##STR1## wherein Ar represents a substituted or substituted 2-hydroxyphenyl group or a pyridyl group, said substitution being selected from the group consisting of a halogen atom, a C.sub.1-6 alkyl group, a hydroxyl group, a hydroxy C.sub.1-6 alkyl group, a nitro group, a C.sub.1-6 alkoxyl group or a carboxyl group, R.sup.1 represents a side chain of an amino acid, X represents --O-- or --NH--, R.sup.2 represents a C.sub.8-22 alkyl group, and n represents 0 or 1, or its salt.

1. Field of the Invention
The present invention relates to a novel amino acid derivative having an excellent active oxygen resistance and exhibiting a good solubility, and an active oxygen-resisting agent comprising the same as an active ingredient.
2. Description of the Related Art
In recent years, various skin disorders and diseases owing to active oxygen species have been reported. For example, it has been known that in aging, canceration, pigmentation and inflammation of the skin by sunlight, especially, ultraviolet light, an active oxygen species deeply participates therein as the cause thereof. Accordingly, if the action of the active oxygen species can be inhibited, it is expected that these disorders and diseases of the skin can be prevented.
Enzymatic antioxidants including superoxide dismutase (SOD), non-enzymatic antioxidants such as ascorbic acid, tocopherol or glutathione, or antioxidant derived from a vegetables, such as tannin are known as substances that inhibits the action of an active oxygen species. However, of these substances, the use of SOD is limited because it is costly and chemically unstable. Also the non-enzymatic antioxidants such as ascorbic acid, tocopherol or glutathione are unstable in many cases, and their effect of inhibiting the active oxygen species is unsatisfactory. The antioxidants derived from the vegetables, such as tannin, are also easily hydrolyzed, and themselves easily oxidized. Accordingly, these substances are problematic in stability in many cases.
Further, in recent years, some investigations have been reported in which a metal ion present in vivo plays a part as a catalyst in the occurrence of the active oxygen species, the occurrence of the active oxygen species is controlled by chelation of the metal ion (for example, Free Radicals in Biology and Medicine, Oxford, Clarendon Press, p. 234, 1989). As a compound having a chelation ability, a disferrioxamine compound is known. Since this compound is, however, too strong a chelator, the balance of the metal ion in vivo is interfered with, and this compound is costly. Besides the disferrioxamine compound, metal ion chelating agents such as 2,2'-dipyridyl, 1,10-phenanthrolene and 2,2'-dipyridylamine have been studied. However, most of these compounds exhibit skin irritation.
Amino acid derivatives which are stable, which show low skin irritation and which have an excellent active oxygen resistance are reported in WO 94/14755 (U.S. Pat. No. 5,594,012). Nevertheless, since the derivatives have a low solubility in a multi-purpose oil solvent such as liquid paraffin or an olive oil, the use thereof is limited.

Amino acid derivatives and active oxygen-resisting agent


An axial gap electronic motor includes a stator having a plurality of poles, and a rotor. Each pole is formed of a stator iron core made of a magnet body and a coil wound therearound. The rotor has a plurality of poles formed of permanent magnet and arranged along a rotation axis direction of said rotor with a predetermined gap provided therebetween. The stator has a magnetic force generating section in which a plurality of the stator iron cores is arranged in a ring shape on a concentric circle with the rotation axis line of the rotor being a center axis. Each of teeth of the stator iron core is provided with a skew.

In an axial gap electronic motor, as disclosed in, for example, Patent Document 1 (Japanese Patent Application Publication No. 2000-253635), a rotor and a stator are arranged opposedly along the axial direction of an output shaft with a predetermined gap provided therebetween. The axial gap electronic motor can be designed so as to be thin as compared with the ordinary motor. For this reason, the motor of this type is preferably used as a hub motor for a power assisted bicycle, a driving motor for an FD drive, and the like.
In a brushless motor made up of a stator iron core made of a magnetic material and a magnet rotor, when the magnetic resistance between the rotor and the stator is changed by the rotation of rotor, cogging torque is produced by attraction and repulsion in the rotation direction. If this cogging torque is high, vibrations and noise occur.
Especially in the case of the axial gap electronic motor, design is made so that the gap between the rotor and the stator is very narrow. Therefore, there is a fear that the rotor is brought into contact with the stator by vibrations, which may provide a cause of breakage, etc.
Thereupon, as one method for decreasing the cogging torque, a stator iron core structure in which a skew (slope) is provided on a stator iron core has been used. Specifically, the skew can achieve an effect of decreasing cogging torque by tilting a part of stator iron core through a predetermined angle along the direction of rotation of the rotor. On the other hand, however, the skew has a drawback of decreased efficiency of conversion to rotational energy.
In the axial gap electronic motor, the stator iron core structure provided with a skew on the stator iron core has not been used from viewpoints of the connection line of coil on the stator iron core, the assembling ability, and the like. Therefore, as shown in a graph of FIG. 6 showing the relationship between cogging torque and electrical angle, when the energization of each stator iron core is switched over, a high cogging torque is produced on the rotor. It is urgent to solve this problem.


The subject matter disclosed herein relates to simulation of bucket testing. In a particular implementation, cohort of users associated with a value for an engagement metric may be selected based at least in part on an intersection of first and second probability distributions. Behavior of the first and second groups may be compared based at least in part on the selected cohort of users.

1. Field
The subject matter disclosed herein relates to simulation of bucket testing.
2. Information
Data processing tools and techniques continue to improve. Information in the form of data is continually being generated or otherwise identified, collected, stored, shared, and analyzed. Databases and other like data repositories are common place, as are related communication networks and computing resources that provide access to such information.
The Internet is ubiquitous; the World Wide Web provided by the Internet continues to grow with new information seemingly being added every second. To provide access to such information, tools and services are often provided, which allow for the copious amounts of information to be searched through in an efficient manner. For example, service providers may allow for users to search the World Wide Web or other like networks using search engines. Similar tools or services may allow for one or more databases or other like data repositories to be searched.
With so much information being available, there is a continuing need for methods and systems that allow for pertinent information to be analyzed in an efficient manner. For example, when conducting studies to determine the impact of a particular product or feature, such as the impact on users of the Internet, an A/B bucket test may be conducted. Such an A/B bucket test may involve showing a random group of users one version of the feature and comparing that group's long term performance with a control group that did not see this feature. However, it is not always possible to foresee the right bucket tests to run. Furthermore, it is not always possible to conduct such an A/B bucket test in a controlled way. Additionally, it is not always possible to conduct such an A/B bucket test retroactively to determine the effect of a feature on users by comparing users who used the feature against ones who didn't.
Reference is made in the following detailed description to the accompanying drawings, which form a part hereof, wherein like numerals may designate like parts throughout to indicate corresponding or analogous elements. It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, it is to be understood that other embodiments may be utilized and structural and/or logical changes may be made without departing from the scope of claimed subject matter. It should also be noted that directions and references, for example, up, down, top, bottom, and so on, may be used to facilitate the discussion of the drawings and are not intended to restrict the application of claimed subject matter. Therefore, the following detailed description is not to be taken in a limiting sense and the scope of claimed subject matter defined by the appended claims and their equivalents.


A gas turbine engine has a low cost combustor liner cooling system combining the benefits of high internal heat removal with improved film cooling by employing a large number of strategically positioned, laser-drilled cooling passages. Cooling air flows through these specially tailored passages to absorb heat from the liner prior to injection as a protective film on the interior surface. The passages are set in staggered rows on a thickened portion of the liner and have a rough internal heat transfer surface and an exit with a steep injection angle to evenly distribute the cooling film along the interior surface of the liner.

Gas turbine power plants are used as the primary propulsive power source for aircraft, in the forms of jet engines and turboprop engines, as auxiliary power sources for driving air compressors, hydraulic pumps, etc. on aircraft, and as stationary power supplies such as backup electrical generators or hospitals and the like. The same basic power generation principles apply for all of these types of gas turbine power plants. A gas turbine engine in its basic form includes a compressor section, a combustion section and a turbine section arranged to provide a generally axially extending flow path for the working gases. Compressed air is mixed with fuel and burned, and the expanding hot combustion gases are directed against stationary turbine guide vanes in the one or more turbine stages of the engine. The vanes turn the high velocity gas flow partially sideways to impinge at the proper angle upon turbine blades mounted on a turbine disk or wheel that is free to rotate. The force of the impinging gas causes the turbine disk to spin at high speed. The power so generated is then used to draw more air into the engine, in the case of the jet propulsion engine, and both draw more air into the engine and also supply shaft power to turn the propeller, an electric generator, or for other uses, in the cases of the other applications. The high velocity combustion gas is then passed out the aft end of the gas turbine which, in the propulsion engine applications, supplies a forward reaction force to the aircraft.
As is well known, the thermal efficiency, and therefore power, produced by any engine is a function of, among other parameters, the temperature of the working gases admitted into the turbine section. That is, all other things being equal, an increase in power from a given engine can be obtained by increasing the combustion gas temperature. This is particularly true for small turboshaft or turboprop engines where very small changes in the operating temperature can substantially affect the engine output. For example, it has been determined in a typical engine of this type that a single degree centigrade increase in the temperature of the working gases can increase the engine power by as much as 15 horsepower. However, as a practical matter, the maximum feasible gas temperature is limited by the useful operating temperature of the component parts in contact with the motive gas and/or the ability to cool these parts below the hot gas temperature.
The maximum gas temperatures occur in the combustion section. A turbine engine conventionally employs either an annular combustor or several cylindrical combustor cans arranged around the circumference of the turbine to contain the burning fuel and air and to produce energetic hot gases for introduction to the turbine section. A transition duct containing guide vanes is typically disposed between the combustors and the first turbine stage to properly direct the flow of hot gases onto the turbine wheel blades.
Various methods for cooling the walls of these combustor components have been tried in order to allow ever higher gas temperatures to be used. Most methods utilize relatively cool uncombusted air from the engine's compressor to both passively cool the exterior of the walls by convection and to actively protect the interior of the walls by film cooling.
The term film cooling as used herein refers to the technique of cooling a surface by maintaining a relatively slow moving layer or film of cool air near the surface so that the layer acts as an insulative barrier to prevent or retard unwanted heating of the surface by the adjacent hot gas stream. In this context, film cooling is distinguished from the more common convection cooling which operates on the completely different principle of maintaining a relatively high velocity flow of cooling air at a surface to carry heat away from the surface rather than insulating the surface from an adjacent heat source.
Several problems exist with the known cooling methods when applied in smaller high performance gas turbine engines. Simple film cooling through slots and/or louvers in the combustor walls does not utilize the full heat sink potential of the cooling air. Also the amount of air so used represents a significant portion of the total air flow from the compressor which would otherwise be available to support combustion and control the burner exit temperature profile, i.e. eliminate hot spots.
To use cooling air more efficiently, recent attempts have focused on providing film cooling through arrays of holes or passages, as opposed to continuous slots, and constructing the passages to provide more active internal wall cooling by convection or impingement, or both. See, for example, U.S. Pat. Nos. 3,420,058; 3,623,711; 3,737,152; 4,242,871; 4,622,821 and 4,773,593. Such complicated cooling schemes raise new problems to be solved. For example, the uniform hole patterns normally employed can result in wall sections that are undercooled on the leading (upstream) edge, well cooled in some central regions, and overcooled on the trailing edge as the cooling film effectiveness increases from row to row in the streamwise direction. In addition, the typical pressure drop through the combustor walls tends to produce blowing ratios much larger than the ideal value near 0.4. Hence, the effusion jets can separate from the hot surface and mix with the bulk flow rather than forming a protective film near the surface.
In view of the foregoing, it is an object of the present invention to provide an improved cooling system for gas turbine combustor walls.
More specifically, it is an object of the invention to provide a durable but lightweight combustor liner having a more effective array of cooling passages therein.
It is a further object of the invention to provide an efficient method of making a porous combustor liner for advanced gas turbine engines.


Branched polymers are prepared from at least (A) at least one monomer having an electron donor moiety, (B) at least one monomer having an electron acceptor moiety, and (C) at least one multifunctional branching agent comprising a urea moiety and at least two N-vinyl groups. The branched polymers are least 20% (by weight) soluble in a solvent for which the corresponding polymer of equal molecular weight made without said multifunctional branching agent is at least 20% (by weight) soluble. Due in part to the wide range of chemistries and solubility and rheological properties, the branched polymers find application in personal care, pharmaceutical/nutritional, and performance chemicals compositions.

1. Field of the Invention
The present invention relates to branched polymers, their properties, compositions and uses thereof.
2. Description of Related Art
There is a desire to extend the performance of polymers beyond what is currently known. In many applications polymers that exhibit low viscosity while maintaining benefits of a higher molecular weight are needed. Such polymers could be used in spraying, pumping, and mixing applications that currently are limited by high viscosity. Likewise, there is a demand for polymers that offer better processability (like blendability, mixability, pumpability, and/or extrudability) to enable entirely new formulations that cannot otherwise be created. Examples of limitations may include high equipment torque, motor failure, and/or product inhomogeneity. One approach to this problem is to synthesize branched polymer variants.
Branching agents are compounds that have the functionality to link one monomer and/or polymer chain to another monomer and/or polymer chain, resulting in polymers that are non-linear polymers, or partially crosslinked polymers. The non-linear and/or partially crosslinked polymers may contain linear polymer portion(s), and combinations thereof.
Among other factors, the resulting polymer properties can depend on the selected monomer(s), branching agent(s), their addition levels, resulting polymer chain densities, and polymerization solvent (or solvent blend), if used. Low addition levels of these branching agents can give rise to branched polymer behavior, meaning that the polymer does not exhibit properties typical of polymers made without the branching agent. Branched polymers may exhibit a lower viscosity than linear polymers of equal molecular weight made without the branching agent, an effect attributed in part to fewer polymer chain entanglement arising from the branched polymer architecture. Because they lack extensive covalent bonds between polymer chains (which is achieved at high branching agent addition levels), a branched polymer exhibits a solubility in the same solvents that solubilize the analogous polymer of equal molecular weight but synthesized without the branching agent(s). As just mentioned, with further increases in the branching agent(s), the resulting polymer can display networked hydrogel behavior, which may include elastic properties such as increased elongational viscosity and/or higher strengths. At high addition levels crosslinked polymers may be created, becoming very rigid or glassy, such as phenol-formaldehyde materials.
It is known to those skilled in the art that polymers having the same chemical composition but having different branching may have different properties. See, for general background, F. W. Billmeyer, Textbook of Polymer Science, 3rd Ed., John Wiley and Sons, New York, 1984; P. J. Flory, Principles of Polymer Chemistry, Cornell University Press, 1953; and C. Tanford, Physical Chemistry of Macromolecules, John Wiley and Sons, New York, 1961.
Related disclosures include WO 2007/096400, WO 2008/032342, and U.S. Pat. Nos. 5,300,606; 5,338,815; 5,534,174 and 5,788,950.
Disclosures of branched polymers, especially poly(N-vinyl-2-pyrrolidone), are provided in U.S. Pat. Nos. 5,082,910; 5,159,034; and 6,294,064. The '910 and '034 inventions provide processes for preparing linear polymers of high molecular weight, as contrasted to branched polymers of low molecular weight. Also known are poly(N-vinyl-2-pyrrolidone)-b-polyester, as disclosed on U.S. patent application 2008/0262105. An additional description of branched polymers includes co-pending U.S. patent application Ser. No. 12/984,926.
Related disclosure also includes international patent application PCT/US11/20208, which is hereby incorporated in its entirety by reference. That application provides polymers resulting from the polymerization of at least one reactive vinyl monomer moiety and a multifunctional N-vinyl formamide crosslinking moiety.
Also related are the following U.S. Pat. Nos. 4,774,285; 4,952,558; 5,202,112; 5,334,375; 5,385,729; 5,534,174; and 5,569,725; 6,197,908; 6,252,026; 7,135,598; 7,579,403; 7,833,585; 7,498,395; and U.S. patent applications 2006/0116492 and 2010/00144958; and international application WO 1992/015628 and 2010/149957


A method determines core geographical information in a document by computing a score for each geographical name found in the document. The computation of the score uses the appearance frequency of the respective geographical name and positional weights assigned to various types of appearance positions of the geographical name in the document. The system determines the core geographical information in the document based on the scores of the geographical names found in the document. The method may further compute aggregated scores of geographical regions related to the geographical names and determine the core geographical information using both the aggregated scores of geographical regions and the scores of individual geographical names to increase accuracy.

Among services provided by the Internet such as keyword search (including content provision of aggregated news and information, for example), document content may be provided according to the relevant geographical information found in the documents. However, with these services provided on the Internet, existing technologies merely extract geographical information that appears within a document when categorizing the document according to its geographical information. Different geographical information may however appear in the same document, and all geographical information may be extracted from the document without differentiation. In reality, core geographical information generally exists in the descriptive content of a document. For example, among the news reports of Sichuan earthquake, the location name "Sichuan" may be extracted as geographical information. At the same time, the news may also mention donations from other provinces and cities to Sichuan. Using an existing method, such geographical information as Guangdong and Beijing may also be extracted. Merely judging from the geographical information extracted this way, the document content might seem as if the news or the information had happened in another place, such as Beijing or Guangdong. At the same time, core geographical information of these news reports should really be recognized as "Sichuan" in this case.
In other words, because existing technologies merely extract geographical information that appears within a document on its face value, multiple pieces of geographical information may be extracted without discerning the true core geographical information of the document from among these pieces of geographical information. This may lead to an inaccurate result for services that are based on the extracted geographical information, such as content provision based on search, and geographically aggregated news and information.

This patent is subject to a terminal disclaimer.

Determining core geographical information in a document


The invention includes methods and systems of processing and managing applications for collocation space. In a computer network including a workstation, a web server, an application server, and a database, the invention assists users in completing applications for collocation space and allows for management of and preparation of responses to those applications. Generally, embodiments of the invention may include submitting and distributing collocation applications and firm orders online; allowing field personnel to respond to and monitor applications online throughout the response and provisioning process; providing notification to field groups and users via e-mail of the events affecting each application; and displaying the current status of each application.

In the United States, telephone service was historically provided almost exclusively by American Telephone and Telegraph, Inc. (AT&T). Following deregulation of the telephone industry in 1984, AT&T was limited to providing long distance telephone service, and local telephone service was thereafter provided by the Regional Bell Operating Companies (RBOCs), such as Bell Atlantic and BellSouth. Thus, following deregulation, the RBOCs served as the exclusive local exchange carriers (LECs), and maintained the subscriber loop between the Public Switched Telephone Network (PSTN) and each individual telephone subscriber.
In 1996, Congress enacted the Telecommunications Act (the "Act") as part of an effort to foster competition in the local telephone industry. Interpretations and enforcement of key portions of the Act were placed in the jurisdiction of the Federal Communications Commission (FCC). The FCC quickly set forth regulations requiring incumbent local exchange carriers (ILECs) to allow any requesting telecommunications carriers, or competitive local exchange carriers (CLECs), to utilize the ILEC's networks to establish a market presence in a region while the CLEC builds its own physical network. These regulations require ILECs to make their network components available using a variety of approaches in which a CLEC purchases service bundles or individual service components from the ILEC and resells those services, as originally bundled, as rebundled by the CLEC or individually, to the CLEC's customers.
The FCC required ILECs to offer collocation space, in some form, to CLECs as early as 1991, but the Act redefined collocation space requirements. As part of the Act's mandate, an ILEC must allow CLECs access to the ILEC's central offices (COs) and provide space in those COs, known as collocation space, for CLEC equipment. A CLEC, for example, may lease certain unbundled elements of the ILEC's network at reduced rates for resale. The CLEC may lease an unbundled port on an end office switch as a point of access to the ILEC's switch and the subscriber loops. The CLEC then connects its own switch network to the unbundled port. Alternatively, the CLEC may operate its own independent switching facilities and loop plant. In either case, the regulatory requirements mandate that the CLEC facilities must be integrated into the PSTN in a seamless manner from the customer's perspective. As such, customers must be able to make and receive telephone calls using existing dialing patterns, without any apparent distinction in processing as a result of service through the CLEC. The regulatory environment therefore places certain burdens on the ILEC to provide an efficient interconnection to the CLEC's facilities and to provide mechanisms for compensation between the parties for calls interconnected between the two carriers' networks.
The interconnection contemplated by the Act provides nondiscriminatory access or interconnection to such services or information as is necessary to allow the requesting CLEC to implement local dialing parity, including access to telephone numbers, operator service, directory assistance, and directory listing, with no unreasonable dialing delays. Federal regulations require that ILECs provide CLECs with a way to request these services as well as the necessary collocation space in the ILEC's CO. For instance, if there is a CO in which a CLEC wants to locate its equipment, the CLEC must complete an application for collocation space and specific federal rules and regulations mandate how and when the ILEC must respond. Among the federal regulations are specified time limits or intervals for standard work activities such as the interval from application submit date to ILEC response date. These time limits may be as short as a few days, such that even a one day delay can become significant.
Previously, a CLEC completed a paper collocation application and sent the completed application by mail, fax, or e-mail to an account team of the ILEC. If there were errors made by the CLEC in submitting the request, the account team was responsible for contacting the CLEC to verify and/or correct the information. The account team then sent the application to applicable field organizations or groups of the ILEC. Copies of applications had to be faxed or shipped next-day air to multiple sites in the region in order to meet the regulatory mandated date intervals. Because there were so many applications being handled manually, applications were often lost or misplaced and an arduous tracking process had to be implemented to ensure proper handling.
Each applicable field group was responsible for providing any information required of it, based on the collocation application, and entering the necessary data into a simple spreadsheet or on paper. The collective information provided by all of the applicable field groups formed the basis for a response to the CLEC. Once the ILEC sent a response, the CLEC replied by paper with a firm order if it wished to order the allocated collocation space. The paper process is faulty for numerous reasons, including time delays, poor handwriting, inaccurate math, and impossible or inconsistent data parameters entered by the CLEC.
The manual, paper-based environment was improved somewhat through the use of PCs and spreadsheets that multiple field groups could access. However, variations still exist because numerous parties are involved in the process and the information is spread among many PCs and is not centrally located. High employee turnover is another problem for CLECs. Because of the high volume of turnover, CLECs do not know with certainty whether a collocation application was sent, what attachments may have been included with the application, where copies of relevant documents were filed, etc. The manual, paper-based and spreadsheet-based systems and methods are simply too labor intensive and prone to errors.
Therefore, there is a need for methods and systems of automating the collocation application process using a computer network where applications for collocation space are processed, responses are generated, firm orders are submitted, and work is provisioned efficiently and accurately.

Systems and methods for processing and managing collocation application over a computer network

BellSouth Intellectual Property Corporation


A method of preparing an antimicrobial preservative system in a substantially anhydrous liquid form is disclosed. The antimicrobial preservative system inhibits or retards microbial growth when an effective antimicrobial amount is subsequently added to a medium capable of supporting undesirable microbial growth. More particularly, the preservative system comprises a condensation product of a 5,5-disubstituted hydantoin and formaldehyde prepared in the presence of a substantially anhydrous, water-miscible, solvent and an alkalizing agent. Also disclosed is a cold-stable, substantially anhydrous liquid preservative system comprising 1,3-dimethylol-5,5-dimethylhydantoin alone or in combination with an effective antimicrobial amount of at least one paraben preservative prepared by an embodiment of the disclosed method.

Antimicrobial preservatives are commonly included in aqueous consumer products and industrial products to prolong the useful life of the product during storage and usage. Such consumer products include personal care products, household products, pet-grooming products and like products which are handled by or come in contact with the skin of the user. Industrial products made up as aqueous media can also come in contact with the skin of the user. The presence of water in such aqueous media can support the growth of microorganisms. While some microorganisms can be innocuous, others can be pathogenic to humans.
Microbial growth or contamination also can and frequently does cause deterioration of the product while the is in the trade channels and in the hands of a consumer. This deterioration can undesirably alter a product's attributes rendering it physically or chemically unaesthetic, or shorten the product's useful life making it unmarketable and, in some instances, even be injurious to humans. Thus antimicrobial preservatives are desirable and necessary for inclusion in aqueous consumer products, and cosmetics in particular.
The term "antimicrobial preservative" as used herein refers to a compound or substance that kills microorganisms or prevents, inhibits or retards their growth and reproduction and is included in a product only at a concentration sufficient to prevent spoilage or prevent the growth of inadvertently added microorganisms. Such an antimicrobial preservative extends the useful life of a product but does not contribute to the claimed effects of the product.
The term "personal care products" as used herein, refers to health and cosmetic beauty aid products generally recognized as being formulated for beautifying and grooming the skin and hair. For example, personal care products include cosmetics, toiletries, and over-the-counter pharmaceutical products intended for topical usage.
The term "household products" as used herein refers to products specially formulated for cleaning or caring for hard surfaces, clothing and the like for use in homes or institutions. For example, household products include detergents, cleansers, fabric softeners, room deodorizers, soaps and the like.
The term "industrial products" as used herein refers to products made up in aqueous medium for use in the industrial workplace or for maintaining hard surfaces and which may come in contact with the worker's hands or skin. For example, industrial products can include water-based paints, cutting oils, latex solutions and the like in which microbial growth can arise during storage. Industrial products are frequently supplied in concentrated form and are normally diluted with water by the user. Microbial growth can lead to deterioration of the diluted product, costly interference with mechanical operations and expose the workers to possible skin irritation problems.
Aqueous personal care products, particularly emulsions and solutions having a pH of between about 5 and about 9, can support the growth of some undesirable microorganisms when sufficient water is present, unless an effective preservative is included Even anhydrous personal care products, such as eye shadows, lipsticks and pancake makeups which are repeatedly used, can be subjected to microbial contamination, especially when the product is moistened during use or adsorbs moisture on the exposed surface.
Cosmetic products, in particular, can be subject to microbial contamination during manufacture, packaging, storage, as well as during use. Consequently, there is a growing need for antimicrobial preservative systems having a broad spectrum of antimicrobial activity for use in almost all cosmetics. Desirably, the antimicrobial preservative system should be non-irritating to the skin and effective against those microorganisms of greatest concern over the range of pH values encountered in cosmetic products. Ideally, the antimicrobial preservative system should be cost effective and in a form that can be easily stored, shipped and incorporated into the product during its manufacture.
A number of antimicrobial preservatives suitable for cosmetics are well known from the cosmetic art and literature. A collection of articles discussing the categories of antimicrobial preservatives frequently used in cosmetics, and describing the properties and efficacy of commercially available preservatives can be found in the Preservatives Documentary/Encyclopedia issue of Cosmet. & Toilet., 102, No. 12 (1987), the pertinent disclosures of which are incorporated herein by reference. For convenience, common category names will be used herein where applicable.
In particular, formaldehyde is known to have effective broad spectrum fungicidal and bactericidal activity. However, for cosmetic acceptability, antimicrobial preservation with formaldehyde is preferably provided by binding formaldehyde to a heterocyclic organic compound to be released slowly over time. These type of antimicrobial preservatives are commonly categorized as formaldehyde donors. A particularly effective formaldehyde donor commonly employed in cosmetics is a condensation product of formaldehyde and a hydantoin, namely, a 5,5-dimethylhydantoin-formaldehyde adduct having methylol functional groups bound to one or both of the nitrogen atoms of the hydantoin ring.
In commercial practice, 1,3-dimethylol-5,5dimethylhydantoin, is a popular broad-spectrum antimicrobial agent widely used in numerous cosmetics. This formaldehyde donor is designated the name of "DMDM Hydantoin" in the CTFA Cosmetic Ingredient Dictionary, Third Edition, (hereafter CTFA Dictionary) published in 1982 by The Cosmetic, Toiletry and Fragrance Association, Inc. (Washington, D.C.). For convenience, the CTFA name will be used.
Antimicrobial preservatives in liquid form are particularly desirable for convenient handling during manufacturing processes Until now, however, liquid DMDM Hydantoin was prepared commercially only as an aqueous solution resulting from the reaction of formaldehyde solution, such as formalin, with 5,5-dimethylhydantoin (DMH). Commercially, formalin is supplied as an aqueous solution of 37 percent by weight of formaldehyde usually with up to about 15 percent methanol added to prevent polymerization of the formaldehyde. A description of one commercial procedure can be found in U.S. Pat. No. 3,987,184 the pertinent disclosures of which are incorporated herein by reference.
Liquid aqueous DMDM Hydantoin, though useful, suffers from the following drawbacks. In commerce, solutions containing about 55 weight percent DMDM Hydantoin generally are not cold stable. The term "cold-stable" as used herein denotes a composition that does not tend to crystallize on standing, storage, or during shipping at a temperature of below about -10 degrees C. (below about 14 degrees F.). Moreover, the presence of water in the DMDM Hydantoin solution limits its utility to water-containing media.
There is a need and desire, therefore, for a cold-stable, water-free liquid antimicrobial preservative system comprising a formaldehyde donor, and DMDM Hydantoin in particular. One method aspect of this invention provides such a liquid antimicrobial preservative system prepared in a substantially anhydrous state which can be subsequently incorporated in a medium containing sufficient water to support microbial growth and effectively inhibit or retard such microbial growth.
From experience, the ideal preservation of aqueous personal care products requires a mixture of antimicrobial preservative compounds to effectively achieve broad spectrum activity against microbial growth. Each preservative compound, however, must be separately dissolved in the product during manufacture which adds to the cost and handling steps involved.
For example, other preservatives which are also widely used in commercial cosmetic practice are phenyl esters of parahydroxybenzoic acid and alkyl esters of parahydroxybenzoic acid containing 1 to about 10 carbon atoms in the alkyl group. These compounds are generally called "paraben esters" or "parabens". The term "paraben preservative" as used herein means that at least one paraben ester compound is present. Paraben preservatives have marked bacteriostatic activity against gram positive bacteria and a marked fungistatic activity, but efficacy against pseudomonads is poor. Typically, one or more of the paraben preservatives are also commonly included in products containing formaldehyde-donor preservatives to enhance broad spectrum antimicrobial efficacy.
The parabens, however, are generally supplied as solids which, though water-soluble, require heating to increase their solubility in water. There is a need and desire, therefore, for an antimicrobial preservative system including a formaldehyde donor and at least one paraben preservative, preferably in a clear liquid form, to eliminate the problems associated with dissolving solid preservatives during manufacturing. Another method aspect of this invention provides such a preservative system in substantially anhydrous liquid form.

Antimicrobial preservative system and method comprising a formaldehyde substituted hydantoin


In embodiments of capacitive touch controls lockout, a computing device includes a touch-screen display for user interaction, and includes one or more capacitive touch controls for user selection as a device input to initiate a device action. The computing device also includes a lockout service that is implemented to disable one or more of the capacitive touch controls based on user interaction with the touch-screen display.

Various types of computing and media devices, such as tablet and portable computers, cell-phones, navigation devices, and desktop display devices include a touch-screen display for user input and touch interaction. Devices with an integrated touch-screen display may also have capacitive buttons or other selectable touch controls at the edges of the touch-screen display. These buttons and touch controls are prone to inadvertent actuation, such as when a user brushes up against a button or touch control while interacting with the touch-screen display on a device. A typical solution is to require the user to press and hold these types of capacitive buttons for a longer duration before an intended action is initiated. However, these types of delays appear to a user as a slow response and may be perceived as a negative user experience. Further, a capacitive button or touch control that is designed for press and hold actuation is not immune to a user inadvertently resting a hand or arm over the control, and initiating an unwanted action on the device.


Content which users may wish to receive may be distributed with interrupting content such that the use of the content on the user's receiver may be interrupted and replaced with the interrupting content. The content which the user wishes to receive may be software, audio, video, graphics or other material and the interrupting content in one embodiment of the prevent invention may be advertisements. In this way, the user's receiver may be utilized to determine when it is appropriate to interrupt the interruptible content with the interrupting content. This may provide a convenient mechanism for reduced price or free distribution of a wide variety of media currently provided only in physical form or only for free without any compensation to the content provider.

This invention relates generally to content distribution.
Broadband content distribution may involve the distribution of television programming to a large number of receivers as well as the distribution of other forms of content. Content which may be amenable to widespread distribution include video, graphics, software, audio and games.
The ability to charge customers for content in many cases means that the type of content that may be distributed may be of higher quality. Thus, pay-per-view television programming is widely accepted.
However, there is a considerable demand for the distribution of content without charge. Conventional television broadcasts subsidize distribution through an advertising scenario. Similarly, in connection with the Internet, a large amount of content is distributed for free with the hope that viewers will patronize advertisers that pay for banner ads that accompany the content.
Thus, it would be desirable to include advertising material or other interruptions in the course of a wide variety of content that might be distributed for free or at reduced charge in a broadband distribution network. However, many content formats are not amenable to the ready incorporation of advertising material. For example, games and software could be distributed with banner ads. However, full screen display of advertisements is generally not viable because there is no way to know when to insert these advertisements in the course of the video game or software operation.
An interruptible content delivery system allows the play of any of a variety of types of selectable content to be paused to permit the automatic insertion of advertising material. Thus, the play of audio, video, games, graphics, software or other media may be paused automatically to allow insertion of advertisements. At the end of the advertisement, the content restarts where it left off.
Generally, advertisers prefer to target their advertisements to specific demographic profiles. For example, advertisers may attempt to target a specific demographic profile based on the nature of a particular type of content such as the nature of the television program. The advertisers may determine that people who enjoy particular types of content, such as particular television programs, may be more likely to purchase particular types of products.
Of course in some potential interruptible content delivery systems, it may not be known in advance what content may be played at any given time. Instead, in many situations, the user may be in control of selecting the content that is played at any particular time.
Thus, there is a need for ways to enable advertising to be inserted in an interruptible content delivery system.


A method of operating a wireless communication apparatus is described. The method includes receiving, a repeated physical downlink control channel (PDCCH) from a base station, performing blind decoding on a plurality of candidate PDCCHs, performing a cyclic redundancy check (CRC), comparing the at least two pieces of control information with each other, and determining whether to terminate the blind decoding based on the comparison.

The inventive concept relates to a wireless communication apparatus, and more particularly, to a method of reducing the probability of a false alarm during decoding.
Wireless communication apparatuses may include a variety of devices such as cell phones, modems, refrigerators, electronic watches, and televisions. A wireless communication apparatus performs encoding and decoding processes to transmit data to or receive data from a base station. The wireless communication apparatus also performs channel scheduling based on information obtained during the decoding process. A check process is then performed by the wireless communication apparatus to determine if the information obtained during the decoding process is sufficient. A failure of the check process will produce an alarm response.
When the check determines a failure, the failure may be due to a false alarm. A false alarm may be a product of the communication environment, and may cause the wireless communication apparatus to perform channel scheduling based on incorrect information.
Channel scheduling with incorrect information produces a mismatch with the channel scheduling of the base station, which causes throughput of the wireless communication apparatus to decrease. It may also result in unnecessary power consumption. Therefore, there is a need in the art for a method to prevent the occurrence of a false alarms to improve communication performance and reduce unnecessary power consumption.

Wireless communication apparatus and operation method thereof


A sun shield is mounted on a bracket that is provided for support of a side-view mirror on a truck cab. The sun shield is mounted horizontally with respect to a ground surface and is located in a position to shield an area just inside the driver's window to protect the arm of the driver from the sun's rays. In the preferred embodiment, the sun shield is made of a high density polymer that is opaque to the sun's rays and is located in a position that does not obstruct the driver's view.

The present invention relates to a truck side-view mirror-mounted sun shield. In the prior art, sun shields of various sizes and configurations are known. However, Applicant is unaware of any such sun shield including all of the features and aspects of the present invention.
The following prior art is known to Applicant:
U.S. Pat. No. 1,717,185 to Caldwell
U.S. Pat. No. 2,020,585 to Stansberry
U.S. Pat. No. 2,681,825 to De Lyra
U.S. Pat. No. 2,863,697 to Watkins
U.S. Pat. No. 4,943,103 to Rosen
U.S. Pat. No. 5,058,942 to Minh
U.S. Pat. No. 5,150,258 to Schmidt et al.
U.S. Pat. No. 5,362,119 to Rosentratter.
None of these references teaches the concept of a sun shield horizontally disposed above a bracket used to mount a side-view mirror on the driver's door of a truck cab and designed to shield an area from the sun shield to area just inside the cab of the vehicle to shield the driver while not obstructing the driver's view.

Truck side-view mirror-mounted sun shield


A device and method for correcting a position of at least one target point relative to a motor vehicle depending on a movement of the motor vehicle over a given number of cycles; starting from at least one target point, forming a first group with adjacent target points depending on a first given characteristic; verifying if the first group is homogeneous depending on a second given characteristic; and calculating a position of a formed group relative to the motor vehicle over the given number of cycles, a formed group corresponding to a target object.

1. Field of the Invention
The present invention concerns a method of detecting a target object for motor vehicle and a detection device for implementing the method.
It finds a particular application in the field of motor vehicles.
2. Description of the Related Art
In the field of motor vehicles, a known prior art method of detecting a target object for motor vehicle uses radar scanning of the front environment of the motor vehicle to return information comprising a set of points representative of the target objects, such as vehicles followed or cross traffic. Such a method is implemented by a radar mounted at the front of a motor vehicle.
A drawback of this prior art is that the information returned by the radar is often noisy and unstable and it is therefore difficult to differentiate target objects from noise, a fixed object from a mobile object, and finally one object close to another in the environment of the motor vehicle.
What is needed, therefore, is a detection device and method that improves over the prior art.

Device and method of detecting a target object for motor vehicle


The present invention relates to a method for preparing a nickel ferrite nanoparticle composite having an inverse spinel structure obtained using a polyol process, a nickel ferrite nanoparticle composite prepared by the method, and a method for selectively binding, separating or purifying a specific protein using the nickel ferrite nanoparticle composite. The method for preparing a magnetic nanoparticle composite according to the present invention includes a one-step hydrothermal synthesis process, and thereby the magnetic nanoparticle composite can be prepared in a simple and economic manner. Also, the nickel ferrite nanoparticles synthesized by the method of the present invention can be strongly magnetic, and also exist in the form of Ni2+ in which Ni binds to a specific protein, thereby preventing loss of separability caused by additional oxidation and repeated recycling of the nanoparticles.

In proteomics, a very important technique is to easily separate and handle a recombinant protein.
Nickel nitrilotriacetic acid (Ni-NTA) beads most frequently used to separate a recombinant protein have been most widely used to purify a protein with an oligohistidine affinity tag (His-tag). A NTA-attached resin is used to fix Ni ions in the Ni-NTA beads and separate a His-tagged protein through coordination chemistry.
In recent years, Xu et al. have synthesized an NTA-attached FePt nanoparticles and an NTA-attached Co/Fe2O3 magnetic nanoparticles and demonstrated the separation of a His-tagged protein by using the magnetic nanoparticles (C. Xu, K. Xu, H. Gu, X. Zhong, Z. Guo, R. Zheng, X. Zhang, B. Xu, J. Am. Chem. Soc. 2004, 126, 3392; C. Xu, K. Xu, H. Gu, R. Zheng, H. Liu, X. Zhang, Z. Guo, B. Xu, J. Am. Chem. Soc. 2004, 126, 9938).
Mirkin et al. have manufactured an Au—Ni—Au triblock nanorod using an anodic alumina membrane and applied it to magnetic separation of a His-tagged protein (K.-B. Lee, S. Park, C. A. Mirkin, Angew. Chem. 2004, 116, 3110; Angew. Chem. Int. Ed. 2004, 43, 3048; B.-K. Oh, S. Park, J. E. Millstone, S. W. Lee, K.-B. Lee, C. A. Mirkin, J. Am. Chem. Soc. 2006, 128, 11825).
However, in the methods published by Xu et al. and Mirkin et al., the nanoparticles for separating a protein are prepared through a series of complicated organic reaction processes.
In more recent years, Hyeon et al. have disclosed Ni/NiO core/shell nanoparticles for selectively binding and magnetically separating a His-tagged protein (I. S. Lee, N. Lee, J. Park, B. H. Kim, Y.-W. Yi, T. Kim, T. K. Kim, I. H. Lee, S. R. Paik, T. Hyeon, J. Am. Chem. Soc. 2006, 128, 10658).
However, the conventional systems have a problem in that the Ni/NiO nanoparticles should undergo a complicated multi-step organic synthesis process since Ni ions binding to a protein are introduced into surfaces of magnetic particles and a shell is formed around a core showing magnetism using silica or a polymer resin to connect a ligand. Also, when the Ni/NiO nanoparticles are recycled several times, the magnetic Ni core is gradually oxidized into NiO which is a semi-ferromagnetic substance. As a result, it is difficult to recycle the Ni/NiO nanoparticles as the magnetism of the Ni/NiO core/shell nanoparticles gradually decreases.
Meanwhile, a conventional method for preparing a ferrite powder includes mixing a metal oxide and drying, calcining and grinding the resulting mixture to prepare particles. However, the process should be performed at a calcination temperature of 1,200° C. or higher since an oxide is used as a starting material, and requires a long grinding process since compositions and particle size of the particles are not uniformly formed due to a solid-state reaction between the particles, which leads to degraded purity and magnetic characteristics caused by contamination.
In addition to the above-described method, methods for preparing a ferrite, such as coprecipitation, hydrothermal synthesis and a flux method, have been used. However, all the methods have problems in that it is difficult to mass-produce nanoparticles since an apparatus has a complicated configuration and is a batch-type apparatus, a manufacturing time is long, the nanoparticles do not exist as a composite since a new phase is formed by a reaction between raw materials, especially upon manufacture of nanocomposite powder, and it is difficult to obtain a powder having a uniform composition.

Nickel ferrite nanoparticle composite and method for preparing same


A semiconductor device includes, a semiconductor element, a wiring member arranged to sandwich the semiconductor element, a sealing resin body. The semiconductor element has an SBD formed thereon with a base material of SiC which is a wide band gap semiconductor. The semiconductor element has two main electrodes on both surfaces. The wiring member includes (i) a heat sink electrically connected to a first main electrode and (ii) a heat sink and a terminal electrically connected to a second main electrode. The semiconductor device further includes an insulator. The insulator has a non-conducting element made of silicon. The insulator has joints on both of two surfaces for mechanical connection of the heat sinks.

When a wide bandgap semiconductor having a wider bandgap than silicon is used as a base material of the semiconductor element, the element size can be made smaller than that made of silicon. When the element size is reduced, the stress acting on the semiconductor element increases. In view of the above or other points not mentioned, there is a need for further improvements in semiconductor devices.


A radio device having a frame structure is proposed for transmitting digital data in a radio communication system, a multiframe being used, which is made of a plurality of containers. The duration of the multiframe can be selected in such a manner that, during this time, a data packet can be filled with voice data of a predetermined bit rate. A container can be selected to be large enough, that a complete transmission frame can be accommodated therein.

Conventional methods in cellular technology allow a frequency band to be used simultaneously by a plurality of radio base stations. In such a radio communication system, several terminals are controlled by a central unit, e.g., a radio base station, which, however, can also be a terminal itself. This central unit defines a radio cell, which indicates the spatial dimensions of the coverage area of the central unit. In general, such radio cells are represented as hexagons or circles in plan view. Such a system is represented in FIG. 1.
FIG. 2 depicts a cellular network having radio cells R1 through R8. However, if a radio cell is now defined, the terminals and the central unit generate interference which extends beyond the boundary of the radio cell. This can completely or partially prevent the operation of a second radio cell that uses the same frequency channel. As an example, the same frequency could be used in radio cells R1 and R4 in FIG. 2. Because of the short distance, signals from R4 interfere with the operation of R1, and vice versa. This problem predominantly occurs when the number of allowed frequency channels is too low.
Various solutions have been proposed for this problem, which are essentially based on separating the radio channels in the frequency or code directions (FDMA and CDMA). Recently, there have also been proposals for separating the channels in the time direction. An example of this is the DECT system.

Radio method and device having a frame structure


Coated fluorescent semiconductor nanoparticles having an organic surface layer of multi-functional surface ligands that include a nanocrystal binding center and one or more covalently attached functional groups or reactive functional groups are described as well as water-dispersible nanoparticles having an organic surface layer or multi-functional surface ligands and methods for the preparation and use of such coated nanoparticles.

Semiconductor nanocrystals are widely used in the study of biochemical and biological systems. Semiconductor nanocrystals can be excited over a wide spectrum of wavelengths and display intense luminescent emission over an extremely narrow bandwidth that is dependent on nanocrystal size and composition. Nanocrystals can also be made insensitive to their medium or environment. These properties allow semiconductor nanocrystals to be used as ultrasensitive luminescent reporters of biological states and processes in many systems.
Semiconductor nanocrystals may be made using techniques known in the art. These methods typically produce nanocrystals having a coating of hydrophobic ligands, such as on their surfaces. Because the surface of the nanocrystal has many binding sites for such ligands, the typical process results in coating of the exposed surface of the nanocrystal with a layer of alkyl groups at the outer surface, and produces a nanocrystal with a surface that is hydrophobic, i.e., incompatible with water.
High temperature pyrolysis gives the synthetic chemist a substantial degree of control over the size of the particles prepared. One disadvantage of this method, however, is that the particles are sequestered in reverse micelles of coordinated, hydrophobic coating of surfactant molecules, such as, for example, trioctyl phosphine (TOP), trioctyl phosphine oxide (TOPO), or tetradecylphosphonic acid (TDPA). While this surfactant layer helps to protect and stabilize the nanocrystal from rapid degradation, they are only dispersible in organic solvents such as chloroform, dichloromethane, hexane, toluene, and pyridine. This is problematic insofar as many applications rely on the fluorescence emission of the semiconductor nanocrystals and require that the nanocrystals be water soluble or water dispersible. In particular, for biological applications, nanocrystals that are soluble or dispersible in water are desirable. Therefore, it may be necessary to make the surface of the nanocrystal, which is typically coated with hydrophobic ligands, compatible with water or biological media.
Although some methods for rendering semiconductor nanocrystals water dispersible have been reported, they are problematic insofar as the treated semiconductor nanocrystals suffer from significant disadvantages that limit their wide applicability. For example, a Cd(OH)2-capped CdS sol exhibits photoluminescent properties that are pH dependent. The sol could be prepared only in a very narrow pH range (pH 8-10) and exhibited a narrow fluorescence band only at a pH of greater than 10. Such pH dependency greatly limits the usefulness of the material; in particular, it is not appropriate for use in biological systems. Other groups have replaced the organic passivating layer of the semiconductor nanocrystal with water-soluble moieties; however, the resultant derivatized semiconductor nanocrystals often exhibit a loss in luminescence. For example, short chain thiols such as 2-mercaptoethanol and 1-thio-glycerol have been used as stabilizers in the preparation of water-soluble CdTe nanocrystals, but the resulting coated semiconductor nanocrystals were not stable and photoluminescent properties degraded with time. Other more exotic capping compounds such as deoxyribonucleic acid (DNA) have been reported with similar results. In addition, subjecting coated nanoparticles to ligand exchange typically results in nanoparticles having a lower quantum yield and lower colloidal stability than the coated nanoparticles prior to ligand exchange, and incomplete ligand exchange can cause batch-to-batch variability.


The presently disclosed embodiments relate generally to an image forming apparatus including: a) an imaging member, and b) a delivery member in contact with a surface of the imaging member, the delivery member has a surface layer comprised of an elastic material impregnated with a functional healing material, and the functional healing material is transferred onto the imaging member by diffusion through the elastic material to the surface of the imaging member. Embodiments also pertain to an improved electrophotographic imaging member including a very thin outer layer on an imaging member surface, where the very thin outer layer includes functional healing materials that act as a lubricant and/or a barrier against moisture and/or surface contaminants. The improved imaging member exhibits improved xerographic performance, such as reduced friction and deletions in high humidity conditions.

The presently disclosed embodiments relate generally to layers that are useful in imaging apparatus members and components, for use in electrophotographic, including digital printing, apparatuses. More particularly, the embodiments pertain to an improved electrophotographic imaging member comprising a very thin outer layer on an imaging member surface, where the very thin outer layer comprises functional healing materials that act as a lubricant and or a barrier against moisture and/or surface contaminants. The very thin outer layer is applied to the imaging member on a nano-scale or molecular level. The improved imaging member exhibits improved xerographic performance, such as improved interaction with a blade cleaner and reduced image deletions in high humidity conditions. The embodiments also pertain to methods and systems for delivering the healing materials to the surface of the imaging member.
In electrophotographic or electrophotographic printing, a charge retentive surface, typically known as a photoreceptor, is electrostatically charged, and then exposed to a light pattern of an original image to selectively discharge the surface in accordance therewith. A resulting pattern of charged and discharged areas on the photoreceptor form an electrostatic charge pattern, known as a latent image, conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder known as toner. Toner is held on image areas by the electrostatic charge on the surface of the photoreceptor. Thus, a toner image is produced in conformity with a light image of an original being reproduced or printed. The toner image may then be transferred to a substrate or support member (e.g., paper) directly or through the use of an intermediate transfer member, and the toner image affixed thereto to form a permanent record of the original to be reproduced or printed. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is useful for light lens copying from an original or printing electronically generated or stored originals such as with a raster output scanner (ROS), where a charged surface may be imagewise discharged in a variety of ways.
The described electrophotographic copying process is well known and is commonly used for light lens copying of an original document. Analogous processes also exist in other electrophotographic printing applications such as, for example, digital laser printing or ionographic printing and reproduction where charge is deposited on a charge retentive surface in response to electronically generated or stored images.
A scorotron has been employed to charge a surface of a photoreceptor. Alternatively, to charge a surface of a photoreceptor, a contact type charging device has been used. The contact type charging device, also termed "bias charge roll" includes a conductive member which is supplied a voltage from a power source with a D.C. voltage superimposed with an A.C. voltage of no less than twice the level of the D.C. voltagen The charging device contacts an image bearing member (photoreceptor) surface, which is a member to be charged. The outer surface of an image bearing member is charged with the a rubbing friction at a contact area. The contact type charging device charges the image bearing member to a predetermined potential. Typically the contact type charging device is in the form of a roll charger such as that disclosed in U.S. Pat. No. 4,387,980, the relative portions thereof incorporated herein by reference. Further, a vicinity type of charging roller may also be suitable to charge a photoreceptor surface, such as in U.S. Pat. No. 6,360,065.
Electrophotographic photoreceptors can be provided in a number of forms. For example, the photoreceptors can be a homogeneous layer of a single material, such as vitreous selenium, or it can be a composite layer containing a photoconductive layer and another material. In addition, the photoreceptor can be layered. Multilayered photoreceptors or imaging members have at least two layers, and may include a substrate, a conductive layer, an optional undercoat layer (sometimes referred to as a "charge blocking layer" or "hole blocking layer"), an optional adhesive layer, a photogenerating layer (sometimes referred to as a "charge generation layer," "charge generating layer," or "charge generator layer"), a charge transport layer, and an optional overcoating layer in either a flexible belt form or a rigid drum configuration. In the multilayer configuration, active layers of the photoreceptor are the charge generation layer (CGL) and the charge transport layer (CTL). Enhancement of charge transport across these layers provides better photoreceptor performance. Multilayered flexible photoreceptor members may include an anti-curl layer on a backside of the substrate, opposite to the side of the active layers, to render a desired photoreceptor flatness.
Conventional photoreceptors are disclosed in the following patents, a number of which describe the presence of light scattering particles in the undercoat layers: Yu, U.S. Pat. No. 5,660,961; Yu, U.S. Pat. No. 5,215,839; and Katayama et al., U.S. Pat. No. 5,958,638. The terms "photoreceptor" or "photoconductor" is generally used interchangeably with the terms "imaging member." The term "electrophotographic" includes "electrophotographic" and "xerographic." The term "charge transport molecule" is generally used interchangeably with the term "hole transport molecule."
To further increase the service life of the photoreceptor, use of overcoat layers has also been implemented to protect photoreceptors and improve performance, such as wear resistance. However, these low wear overcoats are associated with poor image quality due to deletion in a humid environment as the wear rates decrease to a certain level. The low wear overcoated photoreceptors also often possess high friction with a blade cleaner, thus causing inefficient cleaning. The high friction may also increase the risk of cleaning blade damage at an earlier stage. Therefore, in order to improve the image quality and service life of a low wear photoreceptor there is a need to control the surface chemistry of the photoreceptor due to charging and to minimize its deletion. Further there is a need to improve the interaction between the low wear photoreceptor and a blade cleaner for reduced friction and improved cleaning.

Apparatus and methods for delivery of a functional material to an image forming member