Isostasy and origin of the Alpha-Mendeleev Ridge, Arctic Ocean

Thesis (M.S.) University of Alaska Fairbanks, 2006The Alpha-Mendeleev Ridge is an aseismic ridge bisecting the Amerasian Basin, Arctic Ocean. There is no widely accepted theory of formation. Gravity and bathymetry data from the poorly understood ridge are used to constrain the isostatic compensation of the feature in the frequency domain. Spectral analysis of the cross correlation between gravity and bathymetry along nine data transects collected from submarines and ice breakers over the ridge yield an average crustal thickness estimate of 30 km and density estimate of 2.75 g-cm⁻³. It also suggests compensation by local isostasy, as a near-ridge oceanic plateau or an extended fragment of continental shelf. These parameters are used to constrain gravity models of crustal structure. The analysis suggests no difference between the compensation of the Alpha and Mendeleev Ridges. These results are discussed in the broader tectonic context of the Amerasian Basin, in light of the current controversy over the formation of the ridge.1. Introduction -- 1.1. Tectonic history of the Arctic Ocean -- 1.2. The Alpha-Mendeleev Ridge -- 1.3. Purpose -- 2. Spectral analysis -- 2.1. Introduction to spectral analysis -- 2.1.1. Historical results -- 2.1.2. Theory -- 2.1.2a. Calculating admittance -- 2.1.2b. Theoretical isostatic models -- 2.1.3. Methods & data reduction -- 2.2. Shiptrack data -- 2.3. The Alpha-Mendeleev Ridge Complex -- 2.3.1. Results of spectral analysis -- 2.3.2. Isostatic models for the Alpha-Mendeleev Ridge complex -- 2.4. Alpha-Mendeleev Ridge sections -- 2.4.1. Results of spectral analysis -- 2.4.2. Isostatic models for Alpha and Mendeleev Ridges -- 2.5. Discussion of results -- 2.6. Data grids -- 3. Gravity modeling -- 3.1. Introduction -- 3.2. Methods : 3.2.1 2-D Shiptrack models -- 3.3. Results -- 3.3.12-D Crustal models -- 3.3.2. Grid crustal models -- 4. Discussion -- 4.1. Near spreading center hotspot activity -- 4.2. Rifted continental fragment -- 4.3. Consistent tectonic models of the Amerasian basin -- 5. Conclusions -- References -- Appendix

Evidence of Environmental Quenching at Redshift z ~ 2

We report evidence of environmental quenching among galaxies at redshift ~ 2, namely the probability that a galaxy quenches its star formation activity is enhanced in the regions of space in proximity of other quenched, more massive galaxies. The effect is observed as strong clustering of quiescent galaxies around quiescent galaxies on angular scales \theta < 20 arcsec, corresponding to a proper(comoving) scale of 168 (502) kpc at z = 2. The effect is observed only for quiescent galaxies around other quiescent galaxies; the probability to find star-forming galaxies around quiescent or around star-forming ones is consistent with the clustering strength of galaxies of the same mass and at the same redshift, as observed in dedicated studies of galaxy clustering. The effect is mass dependent in the sense that the quenching probability is stronger for galaxies of smaller mass ($\rm{M_*<10^{10} Msun}$) than for more massive ones, i.e. it follows the opposite trend with mass relative to gravitational galaxy clustering. The spatial scale where the effect is observed suggests these environments are massive halos, in which case the observed effect would likely be satellite quenching. The effect is also redshift dependent in that the clustering strength of quiescent galaxies around other quiescent galaxies at z = 1.6 is ~ 1.7 times larger than that of the galaxies with the same stellar mass at z = 2.6. This redshift dependence allows for a crude estimate of the time scale of environmental quenching of low-mass galaxies, which is in the range 1.5 - 4 Gyr, in broad agreement with other estimates and with our ideas on satellite quenching.Comment: 12 pages, 9 figures, Accepted for publication in Ap

Discovery of a dark, massive, ALMA-only galaxy at z~5-6 in a tiny 3-millimeter survey

We report the serendipitous detection of two 3 mm continuum sources found in deep ALMA Band 3 observations to study intermediate redshift galaxies in the COSMOS field. One is near a foreground galaxy at 1.3", but is a previously unknown dust-obscured star-forming galaxy (DSFG) at probable $z_{CO}=3.329$, illustrating the risk of misidentifying shorter wavelength counterparts. The optical-to-mm spectral energy distribution (SED) favors a grey $\lambda^{-0.4}$ attenuation curve and results in significantly larger stellar mass and SFR compared to a Calzetti starburst law, suggesting caution when relating progenitors and descendants based on these quantities. The other source is missing from all previous optical/near-infrared/sub-mm/radio catalogs ("ALMA-only"), and remains undetected even in stacked ultradeep optical ($>29.6$ AB) and near-infrared ($>27.9$ AB) images. Using the ALMA position as a prior reveals faint $SNR\sim3$ measurements in stacked IRAC 3.6+4.5, ultradeep SCUBA2 850$\mu$m, and VLA 3GHz, indicating the source is real. The SED is robustly reproduced by a massive $M^*=10^{10.8}$M$_\odot$ and $M_{gas}=10^{11}$M$_\odot$, highly obscured $A_V\sim4$, star forming $SFR\sim300$ M$_{\odot}$yr$^{-1}$ galaxy at redshift $z=5.5\pm$1.1. The ultrasmall 8 arcmin$^{2}$ survey area implies a large yet uncertain contribution to the cosmic star formation rate density CSFRD(z=5) $\sim0.9\times10^{-2}$ M$_{\odot}$ yr$^{-1}$ Mpc$^{-3}$, comparable to all ultraviolet-selected galaxies combined. These results indicate the existence of a prominent population of DSFGs at $z>4$, below the typical detection limit of bright galaxies found in single-dish sub-mm surveys, but with larger space densities $\sim3 \times 10^{-5}$ Mpc$^{-3}$, higher duty cycles $50-100\%$, contributing more to the CSFRD, and potentially dominating the high-mass galaxy stellar mass function.Comment: Accepted for publication in ApJ. 2 galaxies, too many pages, 8 figures, 2 table

Cytosolic Phospholipase A2α and Eicosanoids Regulate Expression of Genes in Macrophages Involved in Host Defense and Inflammation

Acknowledgments: We thank Dr. Robert Barkley and Charis Uhlson for mass spectrometry analysis. Funding: This work was supported by grants from the National Institutes of Health HL34303 (to C.C.L., R.C.M. and D.L.B), DK54741 (to J.V.B.), GM5322 (to D.L.W.) and the Wellcome Trust (to N.A.R.G. and G.D.B.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Coral reef ecosystem services in the Anthropocene

Coral reefs underpin a range of ecosystem goods and services that contribute to the well‐being of millions of people. However, tropical coral reefs in the Anthropocene are likely to be functionally different from reefs in the past. In this perspective piece, we ask, what does the Anthropocene mean for the provision of ecosystem services from coral reefs? First, we provide examples of the provisioning, regulating, cultural and supporting services underpinned by coral reef ecosystems. We conclude that coral reef ecosystem service research has lagged behind multidisciplinary advances in broader ecosystem services science, such as an explicit recognition that interactions between social and ecological systems underpin ecosystem services. Second, drawing on tools from functional ecology, we outline how these social–ecological relationships can be incorporated into a mechanistic understanding of service provision and how this might be used to anticipate future changes in coral reef ecosystem services. Finally, we explore the emergence of novel reef ecosystem services, for example from tropicalized coastlines, or through changing technological connections to coral reefs. Indeed, when services are conceived as coming from social–ecological system dynamics, novelty in services can emerge from elements of the interactions between people and the ecosystem. This synthesis of the coral reef ecosystem services literature suggests the field is poorly prepared to understand the changing service provision anticipated in the Anthropocene. A new research agenda is needed that better connects reef functional ecology to ecosystem service provision. This research agenda should embrace more holistic approaches to ecosystem service research, recognizing them as co‐produced by ecosystems and society. Importantly, the likelihood of novel ecosystem service configurations requires further conceptualization and empirical assessment. As with current ecosystem services, the loss or gain of services will not affect all people equally and must be understood in the context in which they occur. With the uncertainty surrounding the future of coral reefs in the Anthropocene, research exploring how the benefits to people change will be of great importance

Pellagra: Down Not out If Down and out (and South): Part 2

North-South variation in the supply of meat has always been present Sharing of meat was the rule but in the multi-centric Neolithic revolution when domestication of animals and plants co-evolved class differences became pronounced aristocrats and inferior proletariats and “lesser breeds and lower orders” started to form. The distribution of natural domesticates was uneven with the near-east and a temperate band across Europe well off compared with Africa and the Americas. The Columbian exchange changed this as meat became abundant in the New World who then exported to Europe. Wars, expropriations and genocides were over the meat supply and acquiring pastureland or water. Colonial plantation profits paid for meat imports from “settler colonies” indigenous or poor peoples on low meat pro-pellagrous diets were considered inferior whatever their colour and had poorer health and life expectancy. Attempts to correct hunger in the resultant ramshackle “Third world” concentrated on calories fuelling population booms and busts and delaying demographic, epidemiological and economic transitions. High meat variances are narrowing in China and Asia but need help elsewhere in the South. Dangers of not developing with a safe and sufficient meat supply include the emergence of zoonoses and mass migration. Reparations, rehabilitation and rejuvenation should concentrate on reconstituting a meat commons giving us a shot at redemption and survival

Pellagra: Down Not out If down and out (Part 1)

Pellagra is caused by a dietary deficiency of milk and meat leading to insufficient nicotinamide (vitamin B3), the precursor to nicotinamide adenine dinucleotide (NAD). “Pellagra sine pellagra” was well recognised and may be common as supplementation was never globally implemented and a screening test never developed. Meat and milk intake varies 30-fold globally so there are perhaps 2 billion at risk of deficiency. Such patients will have physical and cognitive stunting, poor conduct and be prone to acute and chronic infections, including TB, and premature ageing, including dementia. Resilience may be poor to NAD-consuming insults whether chemical, microbial or traumatic that conspires to cause brain injury but comes with the opportunity for pre-conception dietary corrections breaking cycles of deprivation and poor educational outcomes. Such individuals may otherwise be subject to discrimination as was the pellagra ridden “Butterfly” caste causing racial and ethic tensions. Poor countries with many having to spend 50-80% of income on food and very little on animal produce cannot develop properly unlike wealthier meat rich empires, past and present. The many benefits of experiments with food programmes and basic income support are because, as Engels curves predict, more is spent on milk and meat enabling demographic, epidemiological, and economic transitions and modernity