The product of a collaboration between scientists, historians and archaeologists, this book breaks new ground in the study of the long-term interaction between environmental factors, including ...climate, and human beings.
•Polyunsaturated fatty acid blood levels have predictive power for disease outcomes.•Both the Omega-3 Index and the n6:n3 ratio have been used to express PUFA status.•The n6:n3 ratio has become ...scientifically out-dated.•The Omega-3 Index, because if included EPA and DHA only, is a preferred metric.
The well-known health effects of the long-chain, marine omega-3 (n-3) fatty acids (FAs) has led to a growing interest in the prognostic value that blood levels of these FAs might have vis-à-vis cardiovascular and neurocognitive diseases. The measurement and expression of n-3 FA levels is not straight-forward, however, and a wide variety of means of expression of n-3 FA status have been used in research and clinical medicine. This has led to considerable confusion as to what “optimal” n-3 FA status is. The n-6:n-3 ratio has enjoyed relatively widespread use, but this apparently simple metric has both theoretical and practical difficulties that have contributed to misunderstandings in this field. Just as the once-popular polyunsaturated:saturated FA ratio has largely disappeared from the nutritional and medical literature, it may be time to replace the n-6:n-3 ratio with a newer metric that focuses on the primary deficiency in Western diets – the lack of eicosapentaenoic and docosahexaenoic acids (EPA and DHA). The Omega-3 Index (red blood cell EPA+DHA) has much to recommend it in this regard.
Abstract
Hubble Space Telescope imaging for 26 giant early-type galaxies, all drawn from the MAST archive, is used to carry out photometry of their surrounding globular cluster (GC) systems. Most of ...these targets are Brightest Cluster Galaxies and their distances range from 24–210 Mpc. The catalogs of photometry, completed with DOLPHOT, are publicly available. The GC color indices are converted to Fe/H through a combination of 12 Gyr single stellar population models and direct spectroscopic calibration of the fiducial color index (F475W–F850LP). All of the resulting metallicity distribution functions (MDFs) can be accurately matched by bimodal-Gaussian functions. The GC systems in all of the galaxies also exhibit shallow metallicity gradients with projected galactocentric distance that average
Z
∼
R
gc
−
0.3
. Several parameters of the MDFs including the means, dispersions, and blue/red fractions are summarized. Perhaps the most interesting new result is the trend of blue/red GC fraction with galaxy mass, which connects with predictions from recent simulations of GC formation within hierarchical assembly of large galaxies. The observed trend reveals two major transition stages: for low-mass galaxies, the metal-rich (red) GC fraction
f
(red) increases steadily with galaxy mass, until halo mass
M
h
≃ 3 × 10
12
M
⊙
. Above this point, more than half the metal-poor (blue) GCs come from accreted satellites and
f
(red) starts declining. But above a still higher transition point near
M
h
≃ 10
14
M
⊙
, the data hint that
f
(red) may start to increase again because the metal-rich GCs also become dominated by accreted systems.
We present a catalog of 422 galaxies with published measurements of their globular cluster (GC) populations. Of these, 248 are E galaxies, 93 are SO galaxies, and 81 are spirals or irregulars. We ...also present updated versions of the GC specific frequency S sub(N) and specific mass S sub(M) versus host galaxy luminosity and baryonic mass. These graphs exhibit the previously known U-shape: highest S sub(N) or S sub(M) values occur for either dwarfs or supergiants, but in the midrange of galaxy size (10 super(9)-10 super(10) L sub(middot in circle)) the GC numbers fall along a well-defined baseline value of S sub(N) Asymptotically = to 1 or S sub(M) = 0.1, similar among all galaxy types. Our results strongly reinforce recent proposals that GC formation efficiency appears to be most nearly proportional to the galaxy halo mass M sub(halo). Finally, we find that an excellent empirical predictor of total GC population for galaxies of all luminosities is N sub(GC) ~ (R sub(e)sigma sub(e)) super(1.3), a result consistent with fundamental plane scaling relations.
Highlights • Metabolic changes are involved in cell proliferation and differentiation during embryogenesis and in stem cells. • Metabolism is regulated by the signaling pathways that control cell ...proliferation and differentiation. • Metabolites can regulate cell signaling.
The Roman Empire was one of the largest and most enduring in world history. In his new book, distinguished historian William V. Harris sets out to explain, within an eclectic theoretical framework, ...the waxing and eventual waning of Roman imperial power, together with the Roman community's internal power structures (political power, social power, gender power and economic power). Effectively integrating analysis with a compelling narrative, he traces this linkage between the external and the internal through three very long periods, and part of the originality of the book is that it almost uniquely considers both the gradual rise of the Roman Empire and its demise as an empire in the fifth and seventh centuries AD. Professor Harris contends that comparing the Romans of these diverse periods sharply illuminates both the growth and the shrinkage of Roman power as well as the Empire's extraordinary durability.
The total mass in the globular cluster (GC) system of a galaxy is empirically a near-constant fraction of the total mass of the galaxy across a range of 105 in galaxy mass. This trend is radically ...unlike the strongly nonlinear behavior of total stellar mass M versus Mh. We discuss extensions of this trend to two more extreme situations: (a) entire clusters of galaxies and (b) the ultra-diffuse galaxies (UDGs) recently discovered in Coma and elsewhere. Our calibration of the ratio from normal galaxies, accounting for new revisions in the adopted mass-to-light ratio for GCs, now gives as the mean absolute mass fraction. We find that the same ratio appears valid for galaxy clusters and UDGs. Estimates of in the four clusters we examine tend to be slightly higher than for individual galaxies, but more data and better constraints on the mean GC mass in such systems are needed to determine if this difference is significant. We use the constancy of to estimate total masses for several individual cases; for example, the total mass of the Milky Way is calculated to be . Physical explanations for the uniformity of are still descriptive, but point to a picture in which massive dense star clusters in their formation stages were relatively immune to the feedback that more strongly influenced lower-density regions where most stars form.
Empirical transformations of selected broadband filters in the Hubble Space Telescope Wide Field Camera 3 (WFC3)/UVIS camera into the BVI system are derived. These conversions employ photometry of ...stars in a standard field in the globular cluster 47 Tucanae that has repeatedly been imaged with both the WFC3 and Advanced Camera for Surveys (ACS) cameras, enabling direct comparisons of photometry for large numbers of stars over a wide range of colors. The photometry of these stars on the ACS camera is used to define their BVI magnitudes, through the standard transformations from Sirianni et al. These BVI magnitudes are then used to define the conversions from the native WFC3 filter system. Results are presented for six WFC3 broadband filters: F438W, F475W, F475X, F555W, F606W, F814W. For these, convenient equations are given to transform (F438W, F475W, F475X) into standard B, (F555W, F606W) into V, and F814W into I. In a parallel study with the same database, a new transformation is presented for conversion of the ACS/WFC F475W filter into B.
Because blood concentrations of n-3 (or omega-3) fatty acids (FAs) (eicosapentaenoic and docosahexaenoic acids) are a strong reflection of dietary intake, it is proposed that a n-3 FA biomarker, the ...omega-3 index (erythrocyte eicosapentaenoic acid plus docosahexaenoic acid), be considered as a potential risk factor for coronary heart disease mortality, especially sudden cardiac death. The omega-3 index fulfills many of the requirements for a risk factor including consistent epidemiologic evidence, a plausible mechanism of action, a reproducible assay, independence from classic risk factors, modifiability, and, most important, the demonstration that raising levels will reduce risk for cardiac events. Measuring membrane concentrations of n-3 FAs is a rational approach to biostatus assessment as these FAs appear to exert their beneficial metabolic effects because of their actions in membranes. They alter membrane physical characteristics and the activity of membrane-bound proteins, and, once released by intracellular phospholipases from membrane stores, they can interact with ion channels, be converted into a wide variety of bioactive eicosanoids, and serve as ligands for several nuclear transcription factors, thereby altering gene expression. The omega-3 index compares very favorably with other risk factors for sudden cardiac death. Proposed omega-3 index risk zones are (in percentages of erythrocyte FAs): high risk, <4%; intermediate risk, 4-8%; and low risk, >8%. Before assessment of n-3 FA biostatus can be used in routine clinical evaluation of patients, standardized laboratory methods and quality control materials must become available.
Abstract Background and aims A recent 19-cohort meta-analysis examined the relationships between biomarkers of omega-3 fatty acids and risk for coronary heart disease (CHD). That study did not, ...however, report hazard ratios (HRs) specifically as a function of erythrocyte eicosapentaenoic (EPA) plus docosahexaenoic (DHA) levels, a metric called the Omega-3 Index in which EPA + DHA content is expressed as a percent of total fatty acids. The Omega-3 Index has been used in several recent studies and is a validated biomarker of omega-3 fatty acid tissue levels, but additional data are needed to confirm (or refute) the originally-proposed clinical cut-points of <4% (higher risk) and 8%–12% (lower risk). Methods The present study was therefore undertaken using published data from this meta-analysis to estimate HRs per 1-SD increase in the Omega-3 Index and median quintile values for this metric across 10 of the cohorts for which the needed data were available. Results The overall mean (SD) for the Omega-3 Index in these 10 cohort studies was 6.1% (2.1%), and the HR for a 1-SD increase was 0.85 (95% confidence interval, 0.80–0.91). Median quintile 1 and 5 levels were 4.2% vs. 8.3%, respectively. Based on these values, we estimate that risk for fatal CHD would have been reduced by about 30% moving from an Omega-3 Index of 4%–8%. Conclusions These findings support the use of <4% and >8% as reasonable therapeutic targets for the Omega-3 Index.
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