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Various proposed optical computing devices involve nonlinear optical operation and use semiconductor optical amplifier (SOA)-based switches as fundamental elements for logic operations. Due to the nonlinear operation, these devices suffer from high power that causes problems in very large-scale optical integration. In this paper, a method is proposed to implement arithmetic operations using a photonic crystal (PhC) cell and eliminate the SOA-based switches altogether. The proposed method is employed on designing an all-optical full adder/subtractor circuit that requires only beam combiners and photonic crystal NOT gates.

In this paper, enhanced designs for ultra-fast all-optical circuits based on the terahertz-optical-asymmetric-demultiplexer (TOAD) adders are proposed. The high speed is achieved due to the use of the nonlinear optical materials and the nonbinary modified signed-digit (MSD) number representation. The proposed all-optical circuits use polarized light to present the trinary digits of the MSD numbers. It will be shown that the polarization-encoded MSD adder uses much less TOADs switches (37.5% less) and it is faster by 33.33% compared to the intensity-encoded ones.

In this paper, a new configuration for the input joint images in the joint transform correlator is proposed for fast real-time binary characters and fingerprints verification. In the proposed scheme, the input joint image has a complementary-reference image and a complementary target image in addition to the reference and the target images. We use the cross-correlation peak value between the reference and the complementary target image and the cross-correlation peak value between the complementary reference and the target images as the criteria to perform the recognition of the target in the input scene. It is shown that these two cross-correlation peak values will be zero if and only if the input target matches the reference image. One advantage of using the proposed scheme is the elimination of the usual and necessary time-consuming normalization of the input images in the general correlation-based matching processes. Another advantage of the proposed scheme is the insensitive to light-sources intensity fluctuations that usually limits the matched-based recognition approaches. The scheme is employed to verify binary characters and fingerprints images; further, it is employed to verify occluded fingerprints target images on one hand, and to determine if a specific part or pattern exists in the target fingerprint image on the other hand.

The spatial light modulators (SLMs) at the Fourier planes of a conventional joint-transform correlation (JTC) are eliminated using simple grating filters such as rectangular and triangular ones. To achieve this goal, two non-conventional real-time JTC architectures are proposed: (a) the grating filter is used along with a heterodyning and one-dimensional optical scanning technique to capture the cross-correlation functions of the input images without major processing and (b) the one-dimensional optical scanning is eliminated to achieve a faster (but a little bit more complicated) processing. The proposed techniques significantly reduce the time processing needed for real-time applications by eliminating the drawbacks of the non-ideal characteristics of the SLMs.

A novel analytical approach is proposed for an accurate estimation of a broad range of Gaussian laser beam diameters. The new approach, based on the Fourier transform and the convolution operations, is used to study the performance of most recently proposed periodic and aperiodic rulings. Further, for applications that require extremely small beam diameter measurements, a new Ronchi-like ruling is proposed; while for applications requiring large beam diameters measurements, various aperiodic non-Ronchi rulings are proposed. Furthermore, for spot-size measurement applications, which range from very small to very large beam diameters, a new single aperiodic exponential ruling is proposed. This new ruling eliminates the necessity of using a large number of rulings for measuring a broad range of beam diameters.

Incontrast to intensity-encoded negabinary modified signed-digit number representation, a polarization-encoding scheme is proposed to design all-optical adders. The utilization of the proposed polarization-encoding produces more efficient circuits in terms of gates numbers and circuit delays. Three all-optical adder circuits are designed using Terahertz-Optical-Asymmetric-Demultiplexer (TOAD) switches,polarization beam splitters, polarization converters, and beam combiners. Itwill be shown that the proposed circuits utilize 51.7%, 45.5%, and 21% less gates and they are faster by 44.4%, 42.9%, and 40%, respectively, than thecorresponding intensity-encoded circuits.

A variety of algorithms for computing complex elementary functions based on the quaternary signed-digit (QSD) number system are proposed. An arithmetic unit that performs parallel one-step addition (subtraction), multiplication, and division is proposed to perform the computations of elementary functions such as square root, logarithmic, exponential, and other related functions. An optoelectronic-correlator-based architecture is suggested for implementing the proposed QSD elementary function algorithms. We used the symbolic substitution technique to reduce the number of the computation rules involved.

A quaternary signed-digit number representations-based arithmetic unit is proposed. The arithmetic unit performs parallel one-step addition (subtraction), multiplication and division. We use the symbolic substitution technique to reduce the number of the computation rules involved in the computation rules. Fast parallel nonrecoded quaternary signed-digit multiplication is proposed using our proposed one-step quaternary signed-digit adder. Also, parallel quaternary signed-digit division is performed in constant time by exploiting an iterative conversion algorithm where in every iterative step a negation operation, an addition operation and two multiplication operations are performed. The execution times of the proposed QSD operations are proportional to log2 n, where n are the length of operands.

A symbolic substitution (SS) based optical numeric processor using quaternary signed-digit (QSD) number representations is proposed. Also, we propose new joint spatial encodings for the QSD numbers that reduce the SS computation rules involved in the processor. Optoelectronic implementation of the proposed QSD adder is feasible. The proposed adder is more compact than recently reported QSD counterparts.

The modified signed-digit number representation is a redundant number system with radix=2. This number system allows limited carry and borrow propagation for addition and subtraction operations. In this paper, symmetrical and non-symmetrical special parallel recoding algorithms for the modified signed-digit numbers are proposed for carry-free arithmetic. Multi-bit parallel digital circuits are presented using AND-OR and/or OR-AND realizations. Also, transformation techniques between the proposed recoding algorithms are provided.

A single-step optoelectronics symbolic substitution scheme to handle parallel modified signed-digit (MSD) arithmetic operations is proposed. Conversion algorithms from MSD numbers into a canonical MSD representation are provided. The canonical MSD numbers have the property that no two consecutive digits are non-zero. The addition operation of two CMSD numbers is performed in one step. It will be shown that through the use of CMSD representation, the number of symbolic substitution rules in an optical content-addressable memory (CAM) based system is significantly reduced. The number of symbolic substitution rules can be further reduced to an optimum value through a proposed shared content-addressable memory optical set-up. Further, the proposed optical scheme doubles the storage efficiency of the shared content-addressable memory.

High-radix number representations such as the quaternary signed-digit (QSD) number system allow higher information storage density, less complexity, fewer system components, and fewer cascaded gates and operations. Arithmetic operations on the quaternary signed-digit are carried out using the powerful symbolic substitution scheme. A single-step or two-step conversion algorithm is employed on the QSD numbers to simplify the higher-order QSD addition process and reduce the number of the optical symbolic substitution rules. The optical addition operation of two QSD numbers is performed in one step. An efficient content-addressable memory (CAM) optical implementation of the QSD addition/subtraction operations is proposed. The QSD number addition/subtraction operations require a significantly reduced number of minterms (symbolic substitution rules) when compared to a similar previously reported technique.

The Journal of Thoracic 3. Bigelow WG, Barnes WT. Ruptured aneurysm of aortic sinus. Ann Surg. 1959;150:117-21. 4. Edwards JE, Burchell HB. The pathological anatomy of deficiencies between the aortic root and the heart, including aortic sinus aneurysms. Thorax. 1957;12:125-39. 5. Sawyers JL, Adams JE, Scott SW Jr. Surgical treatment for aneurysms of the aortic sinuses with aorticoatrial fistula: experimental and clinical study. Surgery. 1975;41:46-8.

The logical equivalence between two powerful optical computing techniques, namely, optical symbolic substitution and optical shadow-casting is investigated. A common basis for both schemes is developed and their roots are traced back to fundamental principles of logic design. Both shadow-casting and symbolic substitution based optical computing operations are shown to be equivalent to logical sum of product operations.

By conbining two powerful optical computing techniques, namely, optical symbolic substitution (OSS) and polarization-encoded optical shadow-casting (POSC), morphological or shape transformation operations are demonstrated. Accordingly, erosion, dilation, opening, and closing operations are realized using both OSS and POSC schemes. These morphological operations are used for noise removal in binary images.

We report the case management of a patient with a methicillin-resistant Staphylococcus aureus intramyocardial abscess adjacent to a previously grafted native right coronary artery. The diagnosis was eventually established by obtaining a gallium scan. This case illustrates the need for maintaining a wide-ranging view of potential causes of bacteremia after cardiac surgery, especially in elderly patients with multiple comorbidities.

Repair of an aortic root aneurysm using a composite graft is sometimes complicated by proximal suture line bleeding, which may be very difficult to control. We adopted a previously described technique of "double overlap" sutures on the annulus and the prosthetic cuff, which has virtually eliminated this complication.