TILLING-by-Sequencing+ to Decipher Oil Biosynthesis Pathway in Soybeans: A New and Effective Platform for High-Throughput Gene Functional Analysis

Reverse genetic approaches have been widely applied to study gene function in crop species; however, these techniques, including gel-based TILLING, present low efficiency to characterize genes in soybeans due to genome complexity, gene duplication, and the presence of multiple gene family members that share high homology in their DNA sequence. Chemical mutagenesis emerges as a genetically modified-free strategy to produce large-scale soybean mutants for economically important traits improvement. The current study uses an optimized high-throughput TILLING by target capture sequencing technology, or TILLING-by-Sequencing⁺ (TbyS⁺), coupled with universal bioinformatic tools to identify population-wide mutations in soybeans. Four ethyl methanesulfonate mutagenized populations (4032 mutant families) have been screened for the presence of induced mutations in targeted genes. The mutation types and effects have been characterized for a total of 138 soybean genes involved in soybean seed composition, disease resistance, and many other quality traits. To test the efficiency of TbyS⁺ in complex genomes, we used soybeans as a model with a focus on three desaturase gene families, GmSACPD, GmFAD2, and GmFAD3, that are involved in the soybean fatty acid biosynthesis pathway. We successfully isolated mutants from all the six gene family members. Unsurprisingly, most of the characterized mutants showed significant changes either in their stearic, oleic, or linolenic acids. By using TbyS⁺, we discovered novel sources of soybean oil traits, including high saturated and monosaturated fatty acids in addition to low polyunsaturated fatty acid contents. This technology provides an unprecedented platform for highly effective screening of polyploid mutant populations and functional gene analysis. The obtained soybean mutants from this study can be used in subsequent soybean breeding programs for improved oil composition traits.     

Creating Decision Trees from Rules using RBDT‐1

Most of the methods that generate decision trees for a specific problem use the examples of data instances in the decision tree–generation process. This article proposes a method called RBDT‐1—rule‐based decision tree—for learning a decision tree from a set of decision rules that cover the data instances rather than from the data instances themselves. The goal is to create on demand a short and accurate decision tree from a stable or dynamically changing set of rules. The rules could be generated by an expert, by an inductive rule learning program that induces decision rules from the examples of decision instances such as AQ‐type rule induction programs, or extracted from a tree generated by another method, such as the ID3 or C4.5. In terms of tree complexity (number of nodes and leaves in the decision tree), RBDT‐1 compares favorably with AQDT‐1 and AQDT‐2, which are methods that create decision trees from rules. RBDT‐1 also compares favorably with ID3 while it is as effective as C4.5 where both (ID3 and C4.5) are well‐known methods that generate decision trees from data examples. Experiments show that the classification accuracies of the decision trees produced by all methods under comparison are indistinguishable.     

The dependence of diffusion length,lifetime and emitter Gummel-number on temperature and doping

Contents In this paper systematic study of the temperature and doping dependences of the energy gap, the diffusion length, the lifetime and the emitter-Gummel number is presented. Based on a special transistor structure, the above parameters could be measured. The doping concentration in the base varies from 10¹⁶/cm³ to 4×10¹⁸/cm³ while the temperature changes from 100 K to 340 K. It is found that the band gap narrowing is smaller than that published in some literature while it agrees with that recently published by del Alamo and Swanson [25]. This result is fully discussed and explained in the text. The diffusion length is nearly independent of temperature, which is interesting for device modeling. On the other hand, the diffusion length decreases with the doping concentrationN _A . The measured lifetime is inversely proportional to doping concentration with powerm wherem=0.6–0.2 depending on temperature. The results show an exponential increase of the emitter Gummel-number with temperature and an increase with doping concentration in the base.

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Die Abhängigkeit der Diffusionslänge, der Trägerlebensdauer und der Emitter-Gummelzahl von der Temperatur und der Dotierungskonzentration

Übersicht Die Arbeit gibt eine systematische Studie wieder über die Temperatur- und Dotierungsabhängigkeit des Bandabstandes, der Diffusionslänge, der Trägerlebensdauer sowie der Emitter-Gummelzahl. An einer speziell präparierten Transistor-Struktur konnten diese Parameter gemessen werden. Die Dotierungskonzentration in der Basis variierte von 10¹⁶ cm^–3 bis 4×10¹⁸ cm^–3, während sich die Temeraturänderung über den Bereich von 100 K bis 340 K erstreckte. Es zeigt sich, daß die Verminderung des Bandabstandes kleiner ist als in einem Teil der Literatur publiziert, daß sic aber übereinstimmt mit dem von del Alamo und Swanson [25] kürzlich veröffentlichten Wert. Dieses Ergebnis wird ausführlich diskutiert und erklärt. Die Diffusionslänge ist annähernd unabhängig von der Temperatur, was für die Bauelemente-Modellierung von Interesse ist. Andererseits nimmt die Diffusionslänge mit wachsender DotierungskonzentrationN _A ab. Die gemessene Ladungsträgerlebensdauer ist proportionalN _A ^–m , wobeim=0,6–0,2 beträgt, abhängig vom Temperaturbereich. Die Ergebnisse zeigen einen exponentiellen Anstieg der Emitter-Gummelzahl mit der Temperatur und eine Zunahme mit der Dotierungskonzentration der Basiszone.

     

Effects of imperfect channel sensing and estimation on the performance of cognitive radio systems

In realistic scenarios of cognitive radio (CR) systems, imperfect channel sensing may occur due to false alarms and miss detections. Channel estimation between the secondary user transmitter and another secondary user receiver is another challenge in CR systems, especially for frequency‐selective fading channels. In this context, this paper presents a study of the effects of imperfect channel sensing and channel estimation on the performance of CR systems. In particular, different methods of channel estimation are analyzed under channel sensing imperfections. Initially, a CR system model with channel sensing errors is described. Then, the expectation maximization (EM) algorithm is implemented in order to learn the channel fading coefficients. By exploiting the pilot symbols and the detected symbols at the secondary user receiver, we can estimate the channel coefficients. We further compare the proposed EM estimation algorithm with different estimation algorithms such as the least squares (LS) and linear minimum mean square error (LMMSE). The expressions of channel estimates and mean squared errors (MSE) are determined, and their dependencies on channel sensing uncertainty are investigated. Finally, to reduce the complexity of EM algorithm, a sub‐optimal algorithm is also proposed. The obtained results show that the proposed sub‐optimal algorithm provides a comparable bit error rate (BER) performance with that of the optimal one yet with less computational complexity.     

Guided particle swarm optimization method to solve general nonlinear optimization problems

The development of hybrid algorithms is becoming an important topic in the global optimization research area. This article proposes a new technique in hybridizing the particle swarm optimization (PSO) algorithm and the Nelder–Mead (NM) simplex search algorithm to solve general nonlinear unconstrained optimization problems. Unlike traditional hybrid methods, the proposed method hybridizes the NM algorithm inside the PSO to improve the velocities and positions of the particles iteratively. The new hybridization considers the PSO algorithm and NM algorithm as one heuristic, not in a sequential or hierarchical manner. The NM algorithm is applied to improve the initial random solution of the PSO algorithm and iteratively in every step to improve the overall performance of the method. The performance of the proposed method was tested over 20 optimization test functions with varying dimensions. Comprehensive comparisons with other methods in the literature indicate that the proposed solution method is promising and competitive.     

Transfer function coefficients for time varying coupled heat transfers in vertically heated hollow concrete bricks

This paper describes a two step numerical procedure to determinate empirical transfer function coefficients (TFCs) for vertically heated hollow concrete bricks. For such systems TFCs cannot be generated using the analytical techniques available in the literature such as the z-transfer function method or the space state representation method because of the nonlinear local character of the heat transfer by natural convection and radiation in the air cells of the hollow concrete bricks. The first step of the procedure consists in predicting coupled heat transfer by conduction, convection, and radiation in realistic time varying conditions using a detailed numerical simulation. In the second step, the results of the simulation (the time-varying heat fluxes at the hollow brick surfaces) are used to obtain empirical transfer function coefficients using an identification technique. Transfer function coefficients are generated for three different types of hollow concrete bricks mostly used in practice. It is shown that the empirical transfer function coefficients permit fast and accurate prediction of heat transfer for thermal excitations that differ markedly from those used to generate these coefficients without solving the complex system of equations governing the coupled heat transfer mechanisms.     

Mechanical and Metallurgical Characterization of HSLA X70Welded Pipeline Steel Subjected to Successive Repairs

The aim of this work is to study the influence of successive weld repairs on the microstructure and the mechanical behavior of the heat-affected zone(HAZ) of an HSLA X70 steel. Detailed microstructural examination combined to grain size measurement showed that beyond the second weld repair, the microstructure of the HAZ undergoes significant change in the grain morphology and grain growth. The results of the X-ray diffraction analyzed using MAUD software indicated an increase in the crystallite size and a decrease in the dislocation density according to the number of weld repair operations. Consequently, a loss of mechanical properties, namely the yield strength and the toughness with the number of weld repairs, was recorded. Beyond the second weld repair operation, the properties of the welded joint do not fulfill the standards applied in piping industry.     

On Architecture of Self-Sustainable Wearable Sensor Node for IoT Healthcare Applications

Wireless Personal Communications - In healthcare applications, the remote monitoring of moving patients depends on wearable nodes that should be mobile. Thus, wearable nodes should be power...     

All-Pass Filters as a Low-Complexity PAPR Reduction Scheme for SC-FDMA System

This paper presents a low-complexity peak-to-average power ratio (PAPR) reduction scheme for single-carrier frequency division multiple access (SC-FDMA) system that is based on all-pass filters (APFs). The basic idea of the APF scheme is that it allows a flat magnitude response with a non-linear phase response. This means that this type of filters passes all frequency content of the input signal, while the phase is severely or intentionally degraded. This idea is well-exploited in this paper for generating random phase sequences that can be treated as multiple versions of an input sequence for the SC-FDMA system. The heart of traditional PAPR reduction techniques such as the conventional selective mapping and blind selective mapping schemes is the generation of multiple random phase sequences for the proper selection of the sequence that achieves the minimum PAPR. This can be accomplished through multiple inverse fast Fourier transform (IFFT) operations, which add more complexity to the system performance. In contrary, with the proposed APF scheme, we generate the signals with different phases through passing the original signal through multiple APFs with different phase responses, which reduces the system complexity.