We propose planar, high numerical aperture (NA), low loss, focusing reflectors and lenses using subwavelength high contrast gratings (HCGs). By designing the reflectance and the phase of non-periodic HCGs, both focusing reflectors and lenses can be constructed. Numerical aperture values as high as 0.81 and 0.96 are achieved for a reflector and lens with very low losses of 0.3 and 0.2 dB, respectively. The design algorithm is also shown to be readily extended to a 2D lens. Furthermore, HCG optics can simultaneously focus the reflected and transmitted waves, with important technological implications. HCG focusing optics are defined by one-step photolithography and thus can be readily integrated with many devices including VCSELs, saturable absorbers, telescopes, CCDs and solar cells.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes a devastating disease in swine. The presence and transmission of PRRSV by boar semen has been demonstrated by using a swine bioassay. In this assay, 4-to 8-week-old pigs were inoculated intraperitoneally with semen from PRRSV-infected boars. Seroconversion of these piglets indicated the presence of PRRSV in semen. Seroconversion in gilts has also been demonstrated following artificial insemination with semen from PRRSV-infected boars. These methods of detecting PRRSV in boar semen are time-consuming, laborious, and expensive. The objective of this study was to develop a reliable and sensitive PCR assay to directly detect PRRSV in boar semen. Primers from open reading frames 1b and 7 of the PRRSV genome were used in nested PCRs. Virus was detected at concentrations as low as 10 infectious virions per ml in PRRSV-spiked semen. Specificity was confirmed by using a nested PCR and a 32 P-labeled oligonucleotide probe. The primers did not react with related arteriviruses or other swine viruses. The PCR assay showed good correlation with the swine bioassay, and both methods were superior to virus isolation. To consistently identify PRRSV in boar semen, the cell fraction was separated by centrifugation at 600 ؋ g for 20 min, a lysis buffer without a reducing agent (2-mercaptoethanol) was used, and nondiluted and 1:20-diluted cell fractions were evaluated by PCR. PRRSV was not reliably detected in the seminal plasma fraction of boar semen. RESULTSOptimization of PCR amplification conditions. To improve the specificity and sensitivity of the PCR, various MgCl 2 concentrations (1.6 to 5 mM), primer concentrations (0.2 to 0.4 M), annealing (50 to 58ЊC) and denaturing (94, 95, or 98ЊC) temperatures, and numbers of cycles (30, 40, or 45) were tested. The optimum product yield was achieved with 5 mM MgCl 2 , 0.4 M primer, annealing and denaturing temperatures of 58 and 95ЊC, respectively, and 30 cycles.

Forty-five Holstein calves were fed milk replacers containing either antibiotics [MRA (oxytetracycline at 138 mg/kg and neomycin at 276 mg/kg), n = 22)] or Enteroguard [MRE, a blend of fructooligosaccharides, allicin, and gut-active microbes at (129 mg/kg, n = 23)] from birth to 5 wk of age to compare effects on average daily gain and on incidence of scours. Performance was evaluated by measuring weight gain, feed efficiency, and fecal scores. The overall body weight gains and severity of scours were not different between treatments, nor were there differences in starter intake or mean body weight gain. During wk 2, the average gain of calves fed MRA was less than that of calves fed MRE (0.07 vs. 0.09 kg/d, P = 0.09), and greater during wk 5 (0.62 vs. 0.51 kg/d, P < 0.01); however, total gain for calves fed MRE was not different from calves fed MRA. Likewise, average feed efficiencies (gain/dry matter intake) were not different. Severity of scours, as measured by fecal scores, and concentrations of serum proteins, an indirect measure of immunoglobulins, were similar for calves fed MRA and MRE. The results suggest that antibiotics in milk replacers can be replaced with compounds such as fructooligosaccharides, probiotics, and allicin to obtain similar calf performance.

Subwavelength High-Contrast Grating (HCG) and its Applications in Optoelectronic Devices Optical grating is a research topic with a long history. It has been extensively studied over the years due to its various applications in holography, spectroscopy, lasers, and many other optoelectronic devices. In this dissertation, we present a novel single-layer subwavelength high-index-contrast grating (HCG) which opens a new era in the study of grating. HCGs can serve as surface normal broadband (∆λ/λ ~35%), high-reflectivity (>99%) mirrors, which can be used to replace conventional distributed Bragg reflectors (DBRs) in optical devices. Different designs of HCGs can also serve as narrow band, surface emitting, high-quality (Q) factor optical resonators or shallow angle reflectors. In this dissertation, we will review the recent advances in high-index-contrast grating and its applications in optoelectronic devices, including vertical-cavity surface-emitting lasers (VCSELs), high-Q optical resonators, and hollow-core waveguides. We first present a novel HCG-based VCSEL where the conventional DBR mirror is replaced with a HCG-based mirror. A systematic and comprehensive review of the experimental and numerical simulation results is presented to demonstrate many desirable 2 attributes of HCG-based VCSELs, including polarization selection, transverse mode control and a large fabrication tolerance. Next, we present an ultra-fast tuning, HCG-based tunable VCSEL. By integrating a mechanically movable actuator with a single-layer HCG as the VCSEL top mirror, precise, wide continuous wavelength tuning (~18 nm) was achieved at room temperature. The small footprint of the HCG enables each of the mechanical actuator dimensions to be scaled down by at least a factor of 10, resulting in a greater than 1000 times reduction in mass, and an increase in the mechanical resonant frequency. It also allows for a record-fast, HCG-based tunable VCSEL with a tuning time in the ~10 ns range to be obtained. Besides the HCG-based VCSELs/tunable VCSELs, we also present a HCG-based surface normal high-Q resonator with a simulated Q-factor as large as 500,000 and an experimentally measured Q-factor of ~14,000. The unique feature of a high-Q with surface normal emission is highly desirable, as the topology facilitates a convenient and high output coupling with free-space or fiber optics. This feature is promising for array fabrication of lasers and filters, as well as high throughput sensor arrays. In addition, we propose a HCG-based hollow-core waveguide design with an ultralow propagation loss of <0.01dB/m, three orders of magnitude lower than the lowest loss of the state-of-art chip-scale hollow waveguides. This novel HCG hollow-core waveguide design will serve as a basic building block in many chip-scale integrated photonic circuits, enabling system-level applications including optical interconnects, optical delay lines, and optical sensors. ____________________________________ Professor Constance J. Chang-Hasnain Dissertation Committee Chair

Previous studies have indicated that porcine reproductive and respiratory syndrome virus (PRRSV) can be identified in and transmitted through boar semen. However, the site(s) of replication indicating the origin of PRRSV in semen has not been identified. To determine how PRRSV enters boar semen, five vasectomized and two nonvasectomized PRRSV-seronegative boars were intranasally inoculated with PRRSV isolate VR-2332. Semen was collected three times weekly from each boar and separated into cellular and cell-free (seminal plasma) fractions. Both fractions were evaluated by reverse transcriptase nested polymerase chain reaction (RT-nPCR) for the presence of PRRSV RNA. Viremia and serostatus were evaluated once weekly, and boars were euthanatized 21 days postinoculation (DPI). Tissues were collected and evaluated by RT-nPCR, virus isolation (VI), and immunohistochemistry to identify PRRSV RNA, infectious virus, or viral antigen, respectively. PRRSV RNA was identified in semen from all vasectomized and nonvasectomized boars and was most consistently found in the cell fraction, within cells identified with a macrophage marker. Viral replication as determined by VI was predominately found within lymphoid tissue. However, PRRSV RNA was widely disseminated throughout many tissues, including the reproductive tract at 21 DPI. These results indicate that PRRSV can enter semen independent of testicular or epididymal tissues, and the source of PRRSV in semen is virus-infected monocytes/macrophages or non-cell-associated virus in serum. PRRSV-infected macrophages in semen may result from infection of local tissue macrophages or may originate from PRRSV-infected circulating monocytes or macrophages.