High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9

One of the most challenging aspects of studying galaxies in the z>~7 universe is the infrequent confirmation of their redshifts through spectroscopy, a phenomenon thought to occur from the increasing opacity of the intergalactic medium to Lya photons at z>6.5. The resulting redshift uncertainties inhibit the efficient search for [C II] in z~7 galaxies with sub-mm instruments such as ALMA, given their limited scan speed for faint lines. One means by which to improve the precision of the inferred redshifts is to exploit the potential impact of strong nebular emission lines on the colors of z~4-8 galaxies as observed by Spitzer/IRAC. At z~6.8, galaxies exhibit IRAC colors as blue as [3.6]-[4.5] ~-1, likely due to the contribution of [O III]+Hb to the 3.6 mum flux combined with the absence of line contamination in the 4.5 mum band. In this paper we explore the use of extremely blue [3.6]-[4.5] colors to identify galaxies in the narrow redshift window z~6.6-6.9. When combined with an I-dropout criterion, we demonstrate that we can plausibly select a relatively clean sample of z~6.8 galaxies. Through a systematic application of this selection technique to our catalogs from all five CANDELS fields, we identify 20 probable z~6.6-6.9 galaxies. We estimate that our criteria select the ~50% strongest line emitters at z~6.8 and from the IRAC colors we estimate a typical [O III]+Hb rest-frame equivalent width of 1085A for this sample. The small redshift uncertainties on our sample make it particularly well suited for follow-up studies with facilities such as ALMA.Comment: In submission to the Astrophysical Journal, updated in response to the referee report, 13 pages, 11 figures, 1 tabl

High-precision photometric redshifts from Spitzer/IRAC : extreme [3.6] - [4.5] colors identify galaxies in the redshift range z ~ 6.6 - 6.9.

One of the most challenging aspects of studying galaxies in the z 7 universe is the infrequent confirmation of their redshifts through spectroscopy, a phenomenon thought to occur from the increasing opacity of the intergalactic medium to Lyα photons at z \u3e 6.5. The resulting redshift uncertainties inhibit the efficient search for [C II] in z ~ 7 galaxies with sub-millimeter instruments such as ALMA, given their limited scan speed for faint lines. One means by which to improve the precision of the inferred redshifts is to exploit the potential impact of strong nebular emission lines on the colors of z ∼ 4 – 8 galaxies as observed by Spitzer/IRAC. At z ~ 6.8, galaxies exhibit IRAC colors as blue as[3.6] [4.5] 1 - ~- , likely due to the contribution of [O III]+Hβ to the 3.6 μm flux combined with the absence of line contamination in the 4.5 μm band. In this paper we explore the use of extremely blue [3.6] [4.5] - colors to identify galaxies in the narrow redshift window z ~ 6.6 – 6.9. When combined with an I-dropout criterion, we demonstrate that we can plausibly select a relatively clean sample of z ~ 6.8 galaxies. Through a systematic application of this selection technique to our catalogs from all five CANDELS fields, we identify 20 probable z ~ 6.6 – 6.9 galaxies. We estimate that our criteria select the ∼50% strongest line emitters at z ~ 6.8 and from the IRAC colors we estimate a typical [O III]+Hb rest-frame equivalent width of 1085 Å for this sample. The small redshift uncertainties on our sample make it particularly well suited for follow-up studies with facilities such as ALMA

Essential EU Climate Law

This thoroughly revised second edition provides an up-to-date account of essential EU climate mitigation law, analysing an area that remains one of the most dynamic fields of EU law. Special attention is paid to the energy sector and to the impact of climate law on broader legal issues, such as energy newtwork regulation and human rights

The Past and Possible Future of EU Climate Law

This chapter provides some food for thought about the next steps the EU may or should take to further improve climate mitigation law

The Past and Possible Future of EU Climate Law

This chapter links the findings of all book chapters and provides some food for thought about the next steps that the EU may or perhaps even should take to further improve climate mitigation law. It reflects upon the general lessons that can be learned from the development of EU climate law, with specific lessons for cost-effectiveness and solidarity. Insights into the broader picture of EU climate regulation are also provided by addressing overarching issues in relation to energy network regulation, multi-level governance and human rights

Purpose, Approach and Outline of the Book

This chapter outlines the purpose, approach and outline of the book 'Essential EU Climate Law' (Edward Elgar Publishing, 2015)

High sFlt-1 Concentrations During Pregnancy Modulate the Ppara Promoter Methylation in the Fetal Liver

Background An adverse prenatal environment significantly increases the risk of chronic metabolic diseases in the offspring. The mechanisms underlying such programming are unclear but may involve epigenetic modifications that lead to altered fetal gene expression. It was demonstrated that poor maternal nutrition affects the DNA methylation status of important transcriptional factors in the liver. However, little attention has been given to other pathological events during pregnancy e.g. increased concentrations of soluble fms-like tyrosine kinase-1 (sFlt-1). Our working hypothesis is that increased sFlt-1 concentrations in the mother can influence the developmental plasticity and the phenotype of the offspring via resetting of DNA methylation marks. Methods Pregnant Sprague-Dawley rats were injected with control or adenovirus overexpressing sFlt-1 on gestational day (GD 8). Fetal plasma, body and organ weight were assessed on GD 19. Microarray analysis was performed to assess the offspring liver gene expressions. The candidate gene methylation status was verified by pyrosequencing. Results Plasma concentrations of sFlt-1 peaked 48 h post injections in the treated animals, and the high concentrations were maintained until the end of the pregnancy. The fetal sFLt-1 concentrations were increased and body weight and length were decreased in the sFlt-1 group. There were no significant differences in the brain weight between the groups, but the livers were smaller in comparison to the respective control group. Microarray analysis revealed 623 differentially expressed genes in the fetal liver. The functional analysis indicated a significant effect on lipid metabolism and in particular fatty acid beta-oxidation. Moreover, Ppara, a transcriptional factor and key regulator of hepatic lipid metabolism, was one of the most induced genes by the high sFlt-1 concentrations present in the mother and in the offspring. In addition, we performed pyrosequencing, to confirm whether Ppara overexpression is accompanied by changes in the methylation of the respective promoter. The promoter region of Ppara revealed decreased methylation in the high sFlt-1 group in comparison to the controls, which is in accordance to the observed gene overexpression. Conclusion Our data show that increased sFlt-1 concentrations in the mother and the offspring lead to growth restriction, brain sparing and Ppara upregulation in the liver. This is accompanied by Ppara promoter hypomethylation. Overall this suggests that epigenetic mechanism may induce the altered phenotype of the offspring via high sFlt-1 maternal concentrations. Support or Funding Information This work was supported by the Netherlands Organization for Health Research and Development (ZonMW, grant number 91211053)