The presence of an unpaired copy of a gene during meiosis triggers the silencing of every copy of that gene in the diploid ascus cell of Neurospora crassa, a phenomenon called Meiotic Silencing. This phenomenon has two stages: trans-sensing and meiotic silencing. If a DNA region is not detected on the opposite homologous chromosome early in meiosis (a trans-sensing failure), a signal corresponding to the unpaired region is produced that transiently silences expression of all homologous sequences. Meiotic silencing is related to RNA Silencing, a phenomenon that employs RNA-dependent RNA Polymerases (RdRPs), Argonautes, and Dicers. Dicers cleave double-stranded RNA (dsRNA) into 21-23 nucleotide RNAs. In the filamentous fungus Neurospora crassa, two RNA silencing pathways have been identified; one is active during mitosis, and the other is active during meiosis. The mitotic RNA silencing pathway, known as “quelling”, involves an RdRP (quelling-deficient-1--qde-1), an Argonaute-like protein (quelling-deficient-2--qde-2), and two Dicer-like proteins (dicer-like-1--dcl-1 and dicer-like-2--dcl-2). Previous studies in N. crassa also revealed the involvement of an RdRP (Suppressor of ascus dominance-1--Sad-1) and an Argonaute-like protein (Suppressor of meiotic silencing-2--Sms-2) in meiotic silencing, suggesting that meiotic silencing is RNA-dependent and raising the question of whether a Dicer is involved in meiotic silencing. In this work, we tested the participation in meiotic silencing of the dcl-1 gene of N. crassa, which codes for a Dicer-like protein we call Suppressor of meiotic silencing-3--Sms-3. Crosses homozygous for mutant alleles of Sms-3 are barren, indicating that the gene is also essential for sexual development. Due to this homozygous sterility, we could only test the involvement of Sms-3 in meiotic silencing in heterozygous crosses. Under these conditions, we observed suppression of the meiotic silencing which would have otherwise been induced by the presence of unpaired DNA of reporter genes. We conclude that the Dicerlike protein Sms-3 is required for both meiotic RNA silencing and sexual development.

A multi band orthogonal frequency division multiplexing (MB-OFDM) compatible ultra wideband (UWB) receiver with narrowband interference (NBI) suppression capability is presented. The average transmit power of UWB system is limited to -41.3 dBm/MHz in order to not interfere existing narrowband systems. Moreover, it must operate even in the presence of unintentional radiation of FCC Class-B compatible devices. If this unintentional radiation resides in the UWB band, it can jam the communication. Since removing the interference in digital domain requires higher dynamic range of analog front-end than removing it in analog domain, a programmable analog notch filter is used to relax the receiver requirements in the presence of NBI. The baseband filter is placed before the variable gain amplifier (VGA) in order to reduce the signal swing at the VGA input. The frequency hopping period of MB-OFDM puts a lower limit on the settling time of the filter, which is inverse proportional to notch bandwidth. However, notch bandwidth should be low enough not to attenuate the adjacent OFDM tones. Since these requirements are contradictory, optimization is needed to maximize overall performance. Two different NBI suppression schemes are tested. In the first scheme, the notch filter is operating for all sub-bands. In the second scheme, the notch filter is turned on during the sub-band affected by NBI. Simulation results indicate that the UWB system with the first and the second suppression schemes can handle up to 6 dB and 14 dB more NBI power, respectively. The results of this work are not limited to MB-OFDM UWB system, and can be applied to other frequency hopping systems.

Reverse auction bidding is an online auction system. A purchaser's primary objective in using a reverse auction is to obtain the lowest possible bid for goods and services on a construction project. With this type of bidding, it is normal that the purchaser will only consider price, instead of a bidders' work history and experience. As a reverse auction is an online service, the common misperception is that a purchaser can reach a broader market to obtain the lowest possible price. It is a controversial bidding system. No previous research has been undertaken by the Texas A&M University Reverse Auction Bidding study group into potential owner interference with the bidding system for a reverse auction. Six bidders were asked to participate in the Reverse Auction Bidding process for a series of construction projects in Houston. Each participant was also asked to complete a Keirsey Temperament Sorter Test type I and II to determine each participant's personality. After the tests, the six participants competed in an online reverse auction bidding game. The primary objective of this research is to analyze the impact of an owner's interference in a reverse auction bidding scenario. In this test, one of the six bidders acted as the owner's surrogate to interfere with an ethical process and reduce the owner's costs. The other five bidders were unaware of the surrogate's role in the bidding. The primary directive given to the surrogate bidder was to drive down the cost of the projects. The results for the research study show that the owner's surrogate can affect the bidding process. Interference results in reduced returns for the bidders when compared to an uncompromised bidding scenario. It is clear that the method used is unethical.

IEEE 802.11 MAC protocol uses two techniques to avoid interference ¡V physical carrier sensing and RTS/CTS handshake (virtual carrier sensing). Ideally, these two techniques can solve most of interference problem. But in normal situation a host cannot receive packet successfully unless the power of receiving signal is much higher than that of interference signal. This fact leads that other host can interfere the reception in farther distance than the distance between the transmitter and the receiver. When the distance between the transmitter and the receiver is larger than certain value, some hosts that are out of the range covered by RTS/CTS packet may still interfere the receiver. This problem can be solved by using a very large physical carrier sensing range, which is limited by antenna and will reduce the network throughput. So it¡¦s not suitable to avoid large interference problem. So far some schemes were proposed to solve or improve this problem, but most of them cause power waste at the same time. In this thesis, we will propose a scheme to look after both interference and power consumption. Simulation results verify that our scheme can solve most interference caused by large interference range with less power consumption.

In This Thesis , We primarily introduce some results with suppression of ground bounce noise in high-speed PCB by the formal researchers and summarize their advantages and weaknesses .In the next section .we explain why the EBG (Electromagnetic Band Gap ) design structure is from PBG (Photonic Band Gap ) concept in optical research field and that its principle can suppress GBN . We also summarize their advantages and weaknesses .In the following part, we define five parameters of EBG design structure to find the optimal solution by HFSS simulation method .The optimal solution can enlarge the bandwidth of suppression of GBN to 5.40GHz.We prove the accuracy of HFSS simulation method by actual measurement . When the EBG basic cell gradually compact from n=9.their characteristics are according to 1.central frequency towards high frequency 2.bandwidth of suppression of GBN is more broadband 3. forbiddance band depth becomes wider. Finally we oppose some new EBG design structures to solve some problems of old EBG design structure .These new EBG design structures can enhance signal integrity (SI) and law frequency response. Include three items 1.Meander design structure 2. Buddha design structure 3. Budder design structure .We also prove the accuracy of HFSS simulation method by actual measurement.

This paper presents design and fabrication of ring cavity semiconductor lasers and optical filters with simple fabrication process. A 1.55

Impellers are important components in the field of precision machine, energy technology, and aerospace industries. Due to their complex geometries and a higher degree of interference, multi-axis machines are requested to product impellers with desired accuracy. The object of this thesis is to improve the five-axis machining efficiency and accuracy. The involved techniques include: the construction of equal depth and equal width tool paths in rough machining, the methods for interference check and avoidance, error evaluation and control of chordal deviation and scallop height, as well as three and five dimension NURBS (Non-uniform Rational B-splines) tool paths generation by a least squares method.

Due to the uncertainties introduced by the propagation channel, and RF and mixed signal circuits imperfections, digital communication receivers require efficient and robust signal acquisition algorithms for timing and carrier recovery, and interfer- ence rejection. The main theme of this work is the development of efficient and robust signal synchronization and interference rejection schemes for narrowband, wideband and ultra wideband communications systems. A series of novel signal acquisition schemes together with their performance analysis and comparisons with existing state-of-the- art results are introduced. The design effort is first focused on narrowband systems, and then on wideband and ultra wideband systems. For single carrier modulated narrowband systems, it is found that conventional timing recovery schemes present low efficiency, e.g., certain feedback timing recov- ery schemes exhibit the so-called hang-up phenomenon, while another class of blind feedforward timing recovery schemes presents large self-noise. Based on a general re- search framework, we propose new anti-hangup algorithms and prefiltering techniques to speed up the feedback timing recovery and reduce the self-noise of feedforward tim- ing estimators, respectively. Orthogonal frequency division multiplexing (OFDM) technique is well suited for wideband wireless systems. However, OFDM receivers require high performance car-rier and timing synchronization. A new coarse synchronization scheme is proposed for efficient carrier frequency offset and timing acquisition. Also, a novel highly accurate decision-directed algorithm is proposed to track and compensate the residual phase and timing errors after the coarse synchronization step. Both theoretical analysis and computer simulations indicate that the proposed algorithms greatly improve the performance of OFDM receivers. The results of an in-depth study show that a narrowband interference (NBI) could cause serious performance loss in multiband OFDMbased ultra-wideband (UWB) sys- tems. A novel NBI mitigation scheme, based on a digital NBI detector and adaptive analog notch filter bank, is proposed to reduce the effects of NBI in UWB systems. Simulation results show that the proposed NBI mitigation scheme improves signifi- cantly the performance of a standard UWB receiver (this improvement manifests as a signal-to-noise ratio (SNR) gain of 9 dB).

Salmonella enterica serovar Enteritidis (SE) is one of the most common food-borne pathogens that cause human salmonellosis. Contamination of consumed poultry products continues to be a global threat to public health. Genetic resistance using genomic approach provides a promising solution to controlling SE infection in poultry. The mechanism of SE resistance in chickens remains elusive. Three different approaches, microarray techology, gene silencing, and computational gene analysis, have been utilized to study SE-induced transcriptional changes of host immune response in the chicken. A whole genome chicken 44K microarray was used to analyze the transcriptome of heterophils from SE-resistant (line A) and SE-susceptible chickens (line B) with/without in vitro SE stimulation. Many differentially expressed immune-related genes were found in the SE-infected to non-infected comparison, where more immune-related genes were down-regulated in line B than line A. These results suggested a similar Toll-like receptor (TLR) regulatory network might exist in heterophils of both lines, and provided strong candidates for further investigating SE resistance and susceptibility in chickens. In the gene silencing study, small interfering RNAs (siRNA) were used to specifically inhibit the expression of NFkB1 in the chicken HD11 macrophage cell line with SE challenge. Genes related to the NF-kB signaling pathway were selected to examine the effect of NFkB1 inhibition on TLR pathway. With 36% inhibition of NFkB1 expression, the results showed an increased expression of TLR4 and interleukin (IL)-6 following SE challenge and suggested a likely inhibitory regulation of NFkB1 on TLR signal pathway. Finally, two novel chicken C-type lectin-like receptors were identified and annotated to chicken CD69 and CD94/NKG2-like with multiple evidences generated by computational (in-silico) sequence analysis. Both genes located in a region on chicken chromosome 1 that is syntenic to mammalian Nature Killer Receptor Complex (NKC) region, which may have existed before the divergence between mammals and aves. While siRNA lays the foundation of using loss-of-function approach on testifying gene-gene interactions, in-silico analysis aids in gathering information of unknown genes of great interest. Both approaches provide great potential to use for down-stream analysis following microarray study.

Ultra-wideband (UWB) system is an indoor communication system, high data rate transmission within 5-10m transmitted range. This system suffers from high dense multipath channels impairment. If the spreading code is not orthogonal in dense multipath channels, severe inter-symbol interference (ISI) will degrade the system performance. In this thesis, we will discuss the performance of various receivers in ultra-wideband channels. Rake receiver can collect signal energy from different multipath. However, the imperfect orthogonal property of spreading code will cause severe ISI and degrade the performance of Rake receiver. Least mean square (LMS) chip equalizer not only combines the energy from different multipath, but also suppresses ISI. But, the complexity is too high to realize. In this thesis, we combine Rake receiver with ISI canceller to enhance system performance. If the canceller is before Rake receiver, we define it as ISIC RAKE. If the canceller is behind Rake receiver, we define it as RAKE ISIC. In the ISI canceller, not only ISI caused by preceding bits is cancelled, but also the ISI caused by following bit is cancelled. In multiuser cases, we are also canceling multi-access interference (MAI). From simulation results, the proposed method outperforms conventional Rake receiver, Rake receiver combined with LMS symbol equalizer, and LMS chip equalizer. The complexity of proposed method is lower than LMS chip equalizer.