University of California, Davis

About: University of California, Davis is a education organization based out in Davis, California, United States. It is known for research contribution in the topics: Population & Gene. The organization has 78770 authors who have published 180033 publications receiving 8064158 citations. The organization is also known as: UC Davis & UCD.

Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z~6 Quasars II: A Sample of 19 Quasars

Abstract: We study the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate-resolution spectra of a sample of 19 quasars at 5.74 5.7: the GP optical depth evolution changes from τ ~ (1 + z)4.3 to (1 + z)11, and the average length of dark gaps with τ > 3.5 increases from 80 comoving Mpc. The dispersion of IGM properties along different lines of sight also increases rapidly, implying fluctuations by a factor of 4 in the UV background at z > 6, when the mean free path of UV photons is comparable to the correlation length of the star-forming galaxies that are thought to have caused reionization. The mean length of dark gaps shows the most dramatic increase at z ~ 6, as well as the largest line-of-sight variations. We suggest using dark gap statistics as a powerful probe of the ionization state of the IGM at yet higher redshift. The sizes of H II regions around luminous quasars decrease rapidly toward higher redshift, suggesting that the neutral fraction of the IGM has increased by a factor of 10 from z = 5.7 to 6.4, consistent with the value derived from the GP optical depth. The mass-averaged neutral fraction is 1%-4% at z ~ 6.2 based on the GP optical depth and H II region size measurements. The observations suggest that z ~ 6 is the end of the overlapping stage of reionization and are inconsistent with a mostly neutral IGM at z ~ 6, as indicated by the finite length of the dark absorption gaps.

Socioeconomic Status, Family Processes, and Individual Development.

Abstract: Research during the past decade shows that social class or socioeconomic status (SES) is related to satisfaction and stability in romantic unions, the quality of parent-child relationships, and a range of developmental outcomes for adults and children. This review focuses on evidence regarding potential mechanisms proposed to account for these associations. Research findings reported during the past decade demonstrate support for an interactionist model of the relationship between SES and family life, which incorporates assumptions from both the social causation and social selection perspectives. The review concludes with recommendations for future research on SES, family processes and individual development in terms of important theoretical and methodological issues yet to be addressed.

Templates for the Solution of Algebraic Eigenvalue Problems: A Practical Guide

Abstract: List of symbols and acronyms List of iterative algorithm templates List of direct algorithms List of figures List of tables 1: Introduction 2: A brief tour of Eigenproblems 3: An introduction to iterative projection methods 4: Hermitian Eigenvalue problems 5: Generalized Hermitian Eigenvalue problems 6: Singular Value Decomposition 7: Non-Hermitian Eigenvalue problems 8: Generalized Non-Hermitian Eigenvalue problems 9: Nonlinear Eigenvalue problems 10: Common issues 11: Preconditioning techniques Appendix: of things not treated Bibliography Index .

Chapter IV A Roll Tube Method for Cultivation of Strict Anaerobes

Abstract: Publisher Summary This chapter presents factors that are considered in developing stringently anaerobic techniques and in describing the procedure and rationale of roll-tube method. A roll-tube method was developed in which agar medium was distributed as a thin layer over the internal surface of test tubes charged with an anaerobic atmosphere for the isolation of obligately anaerobic bacteria of the rumen. In the roll-tube method, exposure of bacteria and culture medium to air is avoided by displacing the air in the culture vessel with an oxygen-free gas, such as carbon dioxide, hydrogen, nitrogen, or mixtures of these gases. Carbon dioxide is the gas of choice because it is heavier than air, relatively cheap, and valuable in buffering. Vessels are stoppered under conditions preventing access of air. The cultures require no special incubators and can be removed and examined with no anaerobic precautions if kept stoppered. If opened, anaerobiosis can be continuously maintained during necessary manipulations, and the culture again closed without exposure to oxygen.

The global distribution of the arbovirus vectors Aedes aegypti and Ae. Albopictus

Abstract: Dengue and chikungunya are increasing global public health concerns due to their rapid geographical spread and increasing disease burden. Knowledge of the contemporary distribution of their shared vectors, Aedes aegypti and Aedes albopictus remains incomplete and is complicated by an ongoing range expansion fuelled by increased global trade and travel. Mapping the global distribution of these vectors and the geographical determinants of their ranges is essential for public health planning. Here we compile the largest contemporary database for both species and pair it with relevant environmental variables predicting their global distribution. We show Aedes distributions to be the widest ever recorded; now extensive in all continents, including North America and Europe. These maps will help define the spatial limits of current autochthonous transmission of dengue and chikungunya viruses. It is only with this kind of rigorous entomological baseline that we can hope to project future health impacts of these viruses.