Multi-Dimensional Constant Energy Modulation

Multi-dimensional modulation is of interest to communications systems researchers due to its potential for increased spectral efficiency and improved performance in nonlinear channels. We present the multi-dimensional constant energy modulation (CEM) technique, which utilizes N-dimensional signal space to improve spectral efficiency while constraining all symbols in a signal constellation to a constant energy. The implementation of the CEM technique is described. Results of the Monte Carlo simulations conducted with linear and nonlinear amplifier effects for N=4, N=5, N=6, N=7 and N=8 modulation dimensions are presented. Key findings include the need to consider bandwidth, spectral efficiency and power trade-offs when selecting the N-dimensional constellation for a required communications system and the need to optimize the constellation to maintain the largest possible minimum Euclidean distance between neighboring vectors while having sufficient vectors to transmit the required symbols. It is observed that the bit error ratio improves with increasing N for the same number of bits per symbol. The CEM system also shows better performance when going through a nonlinear amplifier, especially when compared to an equivalent existing modulation technique.Civilian Defence Science and Technology Agency, SingaporeApproved for public release; distribution is unlimited

Internal audit functions in Singapore : existence, outsourcing and current practices.

The objective of this study is to investigate factors that affect the existence and outsourcing of internal audit functions (IAFs) among listed firms in Singapore

Synthesis of Half-Titanocene Complexes Containing π,π-Stacked Aryloxide Ligands, and Their Use as Catalysts for Ethylene (Co)polymerizations

A family of half-titanocene complexes bearing π,π-stacked aryloxide ligands and their catalytic performances towards ethylene homo-/co- polymerizations were disclosed herein. All the complexes were well characterized, and the intermolecular π,π-stacking interactions could be clearly identified from single crystal X-ray analysis, in which a stronger interaction could be reflected for aryloxides bearing bigger π-systems, e.g., pyrenoxide. Due to the formation of such interactions, these complexes were able to highly catalyze the ethylene homopolymerizations and copolymerization with 1-hexene comonomer, even without any additiveson the aryloxide group, which showed striking contrast to other half-titanocene analogues, implying the positive influence of π,π-stacking interaction in enhancing the catalytic performances of the corresponding catalysts. Moreover, it was found that addition of external pyrene molecules was capable of boosting the catalytic efficiency significantly, due to the formation of a stronger π,π-stacking interaction between the complexes and pyrene molecules

Genome-Wide Dynamic Profiling of Histone Methylation during Nuclear Transfer-Mediated Porcine Somatic Cell Reprogramming.

The low full-term developmental efficiency of porcine somatic cell nuclear transfer (SCNT) embryos is mainly attributed to imperfect epigenetic reprogramming in the early embryos. However, dynamic expression patterns of histone methylation involved in epigenetic reprogramming progression during porcine SCNT embryo early development remain to be unknown. In this study, we characterized and compared the expression patterns of multiple histone methylation markers including transcriptionally repressive (H3K9me2, H3K9me3, H3K27me2, H3K27me3, H4K20me2 and H4K20me3) and active modifications (H3K4me2, H3K4me3, H3K36me2, H3K36me3, H3K79me2 and H3K79me3) in SCNT early embryos from different developmental stages with that from in vitro fertilization (IVF) counterparts. We found that the expression level of H3K9me2, H3K9me3 and H4K20me3 of SCNT embryos from 1-cell to 4-cell stages was significantly higher than that in the IVF embryos. We also detected a symmetric distribution pattern of H3K9me2 between inner cell mass (ICM) and trophectoderm (TE) in SCNT blastocysts. The expression level of H3K9me2 in both lineages from SCNT expanded blastocyst onwards was significantly higher than that in IVF counterparts. The expression level of H4K20me2 was significantly lower in SCNT embryos from morula to blastocyst stage compared with IVF embryos. However, no aberrant dynamic reprogramming of H3K27me2/3 occurred during early developmental stages of SCNT embryos. The expression of H3K4me3 was higher in SCNT embryos at 4-cell stage than that of IVF embryos. H3K4me2 expression in SCNT embryos from 8-cell stage to blastocyst stage was lower than that in the IVF embryos. Dynamic patterns of other active histone methylation markers were similar between SCNT and IVF embryos. Taken together, histone methylation exhibited developmentally stage-specific abnormal expression patterns in porcine SCNT early embryos

Viable short-term directed energy weapon naval solutions: a systems analysis of current prototypes

With conventional weapons nearing their peak capability, the need to identify alternative war fighting solutions suggests a look at Directed Energy Weapons (DEWs). The goal is to change the means by which warfare is conducted to improve operational efficiencies and overall effectiveness. The Naval Postgraduate School Systems Engineering and Analysis (SEA-19B) Capstone project team examined how existing directed energy technologies can provide performance across multiple warfare area domains and mission subsets for the U.S. Navy. The aim was to identify and characterize the capability gaps with conventional weapons systems, produce a coherent vision of naval missions that incorporate DEWs, and generate a roadmap for a DEW fleet. By conducting a thorough Analysis of Alternatives based on system performance, integration, schedule, and cost, the project team identified that the Tactical Laser System (with a laser beam power of 10 kW) provided the best overall capability to defend surface combatants, although none of the analyzed DEWs have the capability to replace a current conventional weapon. The Active Denial System (microwave) provided a niche capability in the Anti-Terrorism/Force Protection mission set.http://archive.org/details/viableshorttermd1094534734Approved for public release; distribution is unlimited

Dynamic reprogramming model for histone lysine methylation during porcine early embryo development.

<p>We propose the following three distinct models about dynamic reprogramming of histone lysine methylation during porcine early embryo development. Red line indicates the first model, the signal intensity from the majority of histone lysine methylation modifications (H3K4me2/me3, H3K9me2/me3, H3K27me2/me3, H3K36me3, and H4K20me2/me3) gradually decrease from pronuclear stage to 8-cell stage and reappear at morula stage. Histone methylations at blastocyst stage show symmetric distribution pattern with similar methylation level between both cell lineages or asymmetric distribution pattern as hypermethylation in TE and hypomethylation in ICM. Green line indicates the second model, the expression level of histone methylation (H3K36me2) invariably keep constant from pronuclear stage to blastocyst stage and the signal intensity is almost consistent between both cell lineages. Blue line indicates the third model, histone methylation (H3K79me2 and H3K79me3) is quickly demethylated after fertilization and always keep low level during development to the blastocyst stage.</p

Dynamic patterns of H3K9me2/3 during IVF and SCNT cleavage-stages embryo development.

<p><b>(A)</b> Representative images of porcine IVF and SCNT embryos at different developmental stages immunostained with an anti-H3K9me2 antibody. Antibody was localized with an Alexa Flour 488-conjugated secondary antibody (green). DNA was stained with propidium iodide (red). Middle panels showed the merged images (yellow) between H3K9me2 signal (green) and DNA staining (red). Red dash line marks the developmental stages with different H3K9me2 signal intensity between IVF and SCNT embryos. Arrow denotes H3K9me2 signal intensity was abnormally higher in SCNT embryos than that in IVF counterparts. White dash circle denotes ICM. <b>(B)</b> Representative images of IVF and SCNT embryos at different developmental stages immunostained with an anti-H3K9me3 antibody. Arrow denotes H3K9me3 signal intensity was abnormally higher in SCNT embryos than that in IVF counterparts. White dash circle denotes ICM. Scale bar = 50 μm. <b>(C)</b> Quantification of H3K9me2 intensity between IVF and SCNT early embryos. (D) Quantification of H3K9me3 intensity between IVF and SCNT early embryos. Blue bars denote IVF group, red bars represent SCNT group. Values are mean ± S.E.M. Different letters (a-b) on the bars indicate a statistically significant difference between IVF and SCNT groups (<i>p</i> < 0.05).</p

Dynamic patterns of H3K4me2/3 during porcine IVF and SCNT cleavage-stages embryo development.

<p><b>(A)</b> Representative images of IVF and SCNT embryos at different developmental stages immunostained with an anti-H3K4me2 antibody. Antibody was localized with an Alexa Flour 488-conjugated secondary antibody (green). DNA was stained with propidium iodide (red). Middle panels showed the merged images (yellow) between H3K4me2 signal (green) and DNA staining (red). Red dash line marks the developmental stages with different H3K4me2 signal intensity between IVF and SCNT embryos. Arrow denotes H3K4me2 signal intensity was abnormally higher in SCNT embryos than that in IVF counterparts. Arrowhead means H3K4me2 signal intensity was abnormally lower in SCNT embryos than that in IVF counterparts. <b>(B)</b> Representative images of IVF and SCNT embryos at different developmental stages immunostained with an anti-H3K4me3 antibody. Arrow denotes H3K4me3 signal intensity was abnormally higher in SCNT embryos than that in IVF counterparts. Scale bar = 50 μm. <b>(C)</b> Quantification of H3K4me2 intensity between IVF and SCNT early embryos. (D) Quantification of H3K4me3 intensity between IVF and SCNT early embryos. Blue bars denote IVF group, red bars represent SCNT group. Values are mean ± S.E.M. Different letters (a-b) on the bars indicate a statistically significant difference between IVF and SCNT groups (<i>p</i> < 0.05).</p