MTDC systems for frequency support base on DC voltage manipulation

This paper presents control strategies for multi-terminal HVDC systems to provide primary frequency support to connected AC networks via coordinated DC voltage manipulation. Inertia response from DC connected large offshore wind farms can also be incorporated without telecommunication based on the detection of DC voltage derivation. Simulation studies ba sed on a 3-terminal HVDC system connecting one large wind farm and two separate AC networks validate the operation of the system during frequency events

Frequency support using multi-terminal HVDC systems based on DC voltage manipulation

This paper investigates the use of multi-terminal HVDC systems to provide primary frequency support to connected AC networks via coordinated DC voltage manipulation. Control schemes for multi-terminal HVDC systems to allow redistribution of active power, based on the idea of “power priority” are proposed. Inertia response from DC connected large offshore wind farms can also be incorporated based on the detection of DC voltage derivation at the offshore converter terminal without the need for telecommunication between the DC terminals. Simulation studies based on a three - terminal HVDC system connecting one large wind farm and two separate AC networks validate the operation of the system during frequency events

Exploring Zeptosecond Quantum Equilibration Dynamics: From Deep-Inelastic to Fusion-Fission Outcomes in 58^{58}Ni+60^{60}Ni Reactions

Energy dissipative processes play a key role in how quantum many-body systems dynamically evolve towards equilibrium. In closed quantum systems, such processes are attributed to the transfer of energy from collective motion to single-particle degrees of freedom; however, the quantum many-body dynamics of this evolutionary process are poorly understood. To explore energy dissipative phenomena and equilibration dynamics in one such system, an experimental investigation of deep-inelastic and fusion-fission outcomes in the $^{58}$Ni+$^{60}$Ni reaction has been carried out. Experimental outcomes have been compared to theoretical predictions using Time Dependent Hartree Fock and Time Dependent Random Phase Approximation approaches, which respectively incorporate one-body energy dissipation and fluctuations. Excellent quantitative agreement has been found between experiment and calculations, indicating that microscopic models incorporating one-body dissipation and fluctuations provide a potential tool for exploring dissipation in low-energy heavy ion collisions.Comment: 11 pages, 9 figures, 1 table, including Supplemental Material - Version accepted for publication in Physical Review Letter

Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements

Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent way. Previous experimental and theoretical studies had produced conflicting conclusions. The experimental MADs reveal an increase in contact time and mass evolution of the quasifission fragments with increasing (N/Z)CN, which is indicative of an increase in the fusion probability. The experimental results are in agreement with microscopic time-dependent Hartree-Fock calculations of the quasifission process. The experimental and theoretical results favor the use of the most neutron-rich projectiles and targets for the production of heavy and superheavy nuclei.Comment: Accepted to PRC as a Rapid Communicatio

The combined effects of genetic risk and perceived discrimination on blood pressure among African Americans in the Jackson Heart Study

Both genomics and environmental stressors play a significant role in increases in blood pressure (BP). In an attempt to further explain the hypertension (HTN) disparity among African Americans (AA), both genetic underpinnings (selected candidate genes) and stress due to perceived racial discrimination (as reported in the literature) have independently been linked to increased BP among AAs. Although Gene x Environment interactions on BP have been examined, the environmental component of these investigations has focused more on lifestyle behaviors such as smoking, diet, and physical activity, and less on psychosocial stressors such as perceived discrimination

Systematic study of quasifission characteristics and timescales in heavy element formation reactions

Superheavy elements can only be created in the laboratory by the fusion of two massive nuclei. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission, the major competitor to fusion in these reactions. The systematics of 42 mass-angle distributions provide information on the global characteristics of quasifission. Deviations from the systematics reveal the major role played by the nuclear structure of the two colliding nuclei in determining the reaction outcome, and in hindering or favouring heavy element production.The authors acknowledge operations support for the ANU Heavy Ion Accelerator Facility from NCRIS, and support from Dr. N. Lobanov and Dr. T. Kibedi and the ANU Heavy Ion Accelerator Facility staff in operating the Linac. Financial support from ARC grants DP130101569, DP140101337, FL110100098, FT120100760 and DE140100784 is acknowledged

Automated Morphological Classification of SDSS Red Sequence Galaxies

(abridged) In the last decade, the advent of enormous galaxy surveys has motivated the development of automated morphological classification schemes to deal with large data volumes. Existing automated schemes can successfully distinguish between early and late type galaxies and identify merger candidates, but are inadequate for studying detailed morphologies of red sequence galaxies. To fill this need, we present a new automated classification scheme that focuses on making finer distinctions between early types roughly corresponding to Hubble types E, S0, and Sa. We visually classify a sample of 984 non-starforming SDSS galaxies with apparent sizes >14". We then develop an automated method to closely reproduce the visual classifications, which both provides a check on the visual results and makes it possible to extend morphological analysis to much larger samples. We visually classify the galaxies into three bulge classes (BC) by the shape of the light profile in the outer regions: discs have sharp edges and bulges do not, while some galaxies are intermediate. We separately identify galaxies with features: spiral arms, bars, clumps, rings, and dust. We find general agreement between BC and the bulge fraction B/T measured by the galaxy modeling package GIM2D, but many visual discs have B/T>0.5. Three additional automated parameters -- smoothness, axis ratio, and concentration -- can identify many of these high-B/T discs to yield automated classifications that agree ~70% with the visual classifications (>90% within one BC). Both methods are used to study the bulge vs. disc frequency as a function of four measures of galaxy 'size': luminosity, stellar mass, velocity dispersion, and radius. All size indicators show a fall in disc fraction and a rise in bulge fraction among larger galaxies.Comment: 24 pages, 20 figures, MNRAS accepte

Evolutionary Patterns and Selective Pressures of Odorant/Pheromone Receptor Gene Families in Teleost Fishes

BACKGROUND: Teleost fishes do not have a vomeronasal organ (VNO), and their vomeronasal receptors (V1Rs, V2Rs) are expressed in the main olfactory epithelium (MOE), as are odorant receptors (ORs) and trace amine-associated receptors (TAARs). In this study, to obtain insights into the functional distinction among the four chemosensory receptor families in teleost fishes, their evolutionary patterns were examined in zebrafish, medaka, stickleback, fugu, and spotted green pufferfish. METHODOLOGY/PRINCIPAL FINDINGS: Phylogenetic analysis revealed that many lineage-specific gene gains and losses occurred in the teleost fish TAARs, whereas only a few gene gains and losses have taken place in the teleost fish vomeronasal receptors. In addition, synonymous and nonsynonymous nucleotide substitution rate ratios (K(A)/K(S)) in TAARs tended to be higher than those in ORs and V2Rs. CONCLUSIONS/SIGNIFICANCE: Frequent gene gains/losses and high K(A)/K(S) in teleost TAARs suggest that receptors in this family are used for detecting some species-specific chemicals such as pheromones. Conversely, conserved repertoires of V1R and V2R families in teleost fishes may imply that receptors in these families perceive common odorants for teleosts, such as amino acids. Teleost ORs showed intermediate evolutionary pattern between TAARs and vomeronasal receptors. Many teleost ORs seem to be used for common odorants, but some ORs may have evolved to recognize lineage-specific odors