Studies on lymphocyte subpopulations and the effect of age on immune competence in turkeys

We characterized the lymphocyte subpopulations and investigated the effect of age on cellular and humoral immunity, development of lymphoid organs, and the relative proportions of CD4+ and CD8+ cells in turkeys. The mitogenic responses of peripheral T cells were poorly developed at hatch but developed rapidly after hatch and reached adult levels by 2 weeks-of-age. The average percentage of CD4+ cells was 45, 29.8, and 26.3 in the thymi, peripheral blood, and spleens, respectively, in turkeys. The mean percentage of CD8+ cells in the thymi, peripheral blood, and spleens of turkeys was 53.8, 13.6, and 15.5, respectively. Age did not influence the relative proportions of CD4+ and CD8+ T cells in the spleens and peripheral blood of turkeys. The mean percentages of IgM+ cells in the bursae and spleens were 78.5 and 26.8, respectively. Day-old turkeys did not develop detectable antibodies to either thymus dependent or independent antigens. However, 2 week or older turkeys showed good humoral responses. Inoculation of BSA at hatch induced tolerance, whereas injection of SRBC did not. Analysis of relative organ weights of turkey lymphoid organs showed that spleens and thymi developed rapidly during the first week-of-age.     

Shaping gain of the partially coherent additive white Gaussiannoise channel

We derive necessary conditions on the channel input and output probability density functions (PDFs) to achieve channel capacity for the additive white Gaussian noise (AWGN) channel with Tikhonov distributed phase error. We show that the Gaussian input does not achieve capacity, and we obtain a lower bound on the shaping gain. The shaping gain can be as large as 2.4 dB at rates as low as 0.5 b/symbol/Hz. This contrasts with the well-known shaping gain for the AWGN channel, which is small at low transmission rates and 1.53 dB at higher rates     

Complex, linear-phase filters for efficient image coding

With the exception of the Haar basis, real-valued orthogonal wavelet filter banks with compact support lack symmetry and therefore do not possess linear phase. This has led to the use of biorthogonal filters for coding of images and other multidimensional data. There are, however, complex solutions permitting the construction of compactly supported, orthogonal linear phase QMF filter banks. By explicitly seeking solutions in which the imaginary part of the filter coefficients is small enough to be approximated to zero, real symmetric filters can be obtained that achieve excellent compression performance     

A two-element antenna for suppression in multipath environments

The design of a two-element antenna for portable transceivers is considered. The antenna consists of a dipole terminated with a parallel loop-capacitor combination. The antenna has a single feed at a point on the loop opposite the junction and does not require external combining circuitry. The capacitor creates a phase shift between the dipole and loop currents, thereby greatly reducing the probability of deep s in the received signal when the antenna is deployed in free-space or in the vicinity of a fixed reflector, where standing wave patterns occur. Theoretical and simulation studies based on multiple incident/reflected plane wave fields typical of multipath environments are used to quantify the reduction in probability. Simulation results are presented for three antenna types: a dipole antenna, a loop-dipole antenna without a capacitor, and the loop-dipole antenna with capacitor. The results are verified by field measurements on an automated outdoor test range, where the incidence angle and distance from the reflector are varied. With a single incident plane wave, the loop-dipole-capacitor (LDC) design reduces the probability of deep s in the received signal by up to two orders of magnitude at low signal-to-noise ratios (SNRs) when compared with the standard dipole antenna and the loop-dipole antenna without the capacitor. The performance advantage of the new design decreases as the number of incident waves increases; however, it performs at least as well as the dipole antenna in all cases studied.     

Determinants of graft survival after renal transplantation

We studied multiple determinants of graft survival at a single center and the effects of nonimmunologic graft loss on transplant survival. This retrospective study examined the results of 589 cadaver donor transplants performed between 1986 and 1992. Graft survival rates were calculated using Kaplan-Meier estimates for both overall graft survival (all causes of graft loss) and immunologic graft survival (function lost due to acute or chronic rejection and noncompliance). Cadaver graft survival was significantly poorer with an increasing degree of DR mismatch (P=0.02). An analysis of pretransplant variables showed graft loss risk was highest with greater DR mismatches, two B-antigen mismatch, higher donor serum creatinine, and younger recipient age. After transplantation, acute rejection was the most significant factor associated with long-term graft survival. Our data demonstrate a significant advantage for zero DR and one DR mismatch cadaver donor transplants, with excellent immunologic graft survival. This study suggests that a combination of immediate graft function, prevention of acute rejection by appropriate early immunosuppressive therapy, and acceptable DR match enhances cadaveric graft survival.     

Symmetric trellis-coded vector quantization

We present here design techniques for trellis-coded vector quantizers with symmetric codebooks that facilitate low-complexity quantization as well as partitioning into equiprobable sets for trellis coding. The quantization performance of this coder on the independently identically distributed (i.i.d.) Laplacian source matches the performance of trellis-based scalar-vector quantization (TB-SVQ), but requires less computational complexity     

Bounds on the a priori index crossover probabilities fortrellis-based channel codes

This paper derives truncated union bounds on the a priori index crossover probabilities p(j|i) that result when an n-bit data index i is convolutionally encoded, transmitted over a noisy channel, and decoded with the Viterbi algorithm, giving received index j. The bounds are derived with a modified transfer function technique, using n-stage state transition matrices with symbolic labels. The technique is easily automated with commercial symbolic algebra packages. Bounds are obtained for convolutional and trellis-coded modulation (TCM) codes, over binary symmetric and additive white Gaussian noise (AWGN) channels. A joint source channel coding example demonstrates that the bounds on p(j|i) developed in this paper can give a 13-dB accuracy improvement in end-to-end signal-to-noise ratio (SNR) predictions, when compared to predictions based on bounds on the delivered bit error probability P_b     

Crosstalk-Aware Channel Coding Schemes for Energy Efficient and Reliable NOC Interconnects

Network-on-chip (NOC) is emerging as a revolutionary methodology to integrate numerous intellectual property blocks in a single die. It is the packet switching-based communications backbone that interconnects the components on multicore system-on-chip (SoC). A major challenge that NOC design is expected to face is related to the intrinsic unreliability of the interconnect infrastructure under technology limitations. By incorporating error control coding schemes along the interconnects, NOC architectures are able to provide correct functionality in the presence of different sources of transient noise and yet have lower overall energy dissipation. In this paper, designs of novel joint crosstalk avoidance and triple-error-correction/quadruple-error-detection codes are proposed, and their performance is evaluated in different NOC fabrics. It is demonstrated that the proposed codes outperform other existing coding schemes in making NOC fabrics reliable and energy efficient, with lower latency.