CANDELS Sheds Light on the Environmental Quenching of Low-mass Galaxies

Guo, Yicheng,Bell, Eric F.,Lu, Yu,Koo, David C.,Faber, S. M.,Koekemoer, Anton M.,Kurczynski, Peter,Lee, Seong-Kook,Papovich, Casey,Chen, Zhu,Dekel, Avishai,Ferguson, Henry C.,Fontana, Adriano,Giavalis American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.841 No.2

<P>We investigate the environmental quenching of galaxies, especially those with stellar masses (M-*) < 10(9.5) Me-circle dot, beyond the local universe. Essentially all local low-mass quenched galaxies (QGs) are believed to live close to massive central galaxies, which is a demonstration of environmental quenching. We use CANDELS data to test whether or not such a dwarf QG-massive central galaxy connection exists beyond the local universe. For this purpose, we only need a statistically representative, rather than complete, sample of low-mass galaxies, which enables our study to z greater than or similar to 1.5. For each low-mass galaxy, we measure the projected distance (d(proj)) to its nearest massive neighbor (M-* > 10(10.5) M-circle dot) within a redshift range. At a given z and M-*, the environmental quenching effect is considered to be observed if the d(proj) distribution of QGs (d(proj)(Q)) is significantly skewed toward lower values than that of star-forming galaxies (d(proj)(SF)). For galaxies with 10(8) M-circle dot < M-* < 10(10) M-circle dot, such a difference between d(proj)(Q) and d(proj)(SF) is detected up to z similar to 1. Also, about 10% of the quenched galaxies in our sample are located between two and four virial radii (R-Vir) of the massive halos. The median projected distance from low-mass QGs to their massive neighbors, d(proj)(Q)/R-Vir, decreases with satellite M-* at M-* less than or similar to 10(9.5) M-circle dot, but increases with satellite M-* at M-* greater than or similar to 10(9.5) M-circle dot. This trend suggests a smooth, if any, transition of the quenching timescale around M-* similar to 10(9.5) M-circle dot at 0.5 < z < 1.0.</P>

Mortality burden of diurnal temperature range and its temporal changes: A multi-country study

Lee, Whanhee,Bell, Michelle L.,Gasparrini, Antonio,Armstrong, Ben G.,Sera, Francesco,Hwang, Sunghee,Lavigne, Eric,Zanobetti, Antonella,Coelho, Micheline de Sousa Zanotti Stagliorio,Saldiva, Paulo Hila Elsevier 2018 Environment international Vol.110 No.-

<P><B>Abstract</B></P> <P>Although diurnal temperature range (DTR) is a key index of climate change, few studies have reported the health burden of DTR and its temporal changes at a multi-country scale. Therefore, we assessed the attributable risk fraction of DTR on mortality and its temporal variations in a multi-country data set. We collected time-series data covering mortality and weather variables from 308 cities in 10 countries from 1972 to 2013. The temporal change in DTR-related mortality was estimated for each city with a time-varying distributed lag model. Estimates for each city were pooled using a multivariate meta-analysis. The results showed that the attributable fraction of total mortality to DTR was 2.5% (95% eCI: 2.3–2.7%) over the entire study period. In all countries, the attributable fraction increased from 2.4% (2.1–2.7%) to 2.7% (2.4–2.9%) between the first and last study years. This study found that DTR has significantly contributed to mortality in all the countries studied, and this attributable fraction has significantly increased over time in the USA, the UK, Spain, and South Korea. Therefore, because the health burden of DTR is not likely to reduce in the near future, countermeasures are needed to alleviate its impact on human health.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We analyzed the health burden of diurnal temperature range (DTR) for 10 countries. </LI> <LI> In addition, we estimated the temporal changes in the mortality burden of DTR. </LI> <LI> The excessive risk and attributable risk of DTR was significant in most countries. </LI> <LI> The mortality burden due to DTR has been increased during decades (1972–2013). </LI> <LI> We conclude that the effect of DTR will not decrease in the near future. </LI> </UL> </P>

Longer-Term Impact of High and Low Temperature on Mortality: An International Study to Clarify Length of Mortality Displacement

Armstrong, Ben,Bell, Michelle L.,de Sousa Zanotti Stagliorio Coelho, Micheline,Leon Guo, Yue-Liang,Guo, Yuming,Goodman, Patrick,Hashizume, Masahiro,Honda, Yasushi,Kim, Ho,Lavigne, Eric,Michelozzi, Pao U.S. Dept. of Health, Education, and Welfare, Publ 2017 Environmental health perspectives Vol.125 No.10

<P><B>Background:</B></P><P>In many places, daily mortality has been shown to increase after days with particularly high or low temperatures, but such daily time-series studies cannot identify whether such increases reflect substantial life shortening or short-term displacement of deaths (harvesting).</P><P><B>Objectives:</B></P><P>To clarify this issue, we estimated the association between annual mortality and annual summaries of heat and cold in 278 locations from 12 countries.</P><P><B>Methods:</B></P><P>Indices of annual heat and cold were used as predictors in regressions of annual mortality in each location, allowing for trends over time and clustering of annual count anomalies by country and pooling estimates using meta-regression. We used two indices of annual heat and cold based on preliminary standard daily analyses: <I>a</I>) mean annual degrees above/below minimum mortality temperature (MMT), and <I>b</I>) estimated fractions of deaths attributed to heat and cold. The first index was simpler and matched previous related research; the second was added because it allowed the interpretation that coefficients equal to 0 and 1 are consistent with none (0) or all (1) of the deaths attributable in daily analyses being displaced by at least 1 y.</P><P><B>Results:</B></P><P>On average, regression coefficients of annual mortality on heat and cold mean degrees were 1.7% [95% confidence interval (CI): 0.3, 3.1] and 1.1% (95% CI: 0.6, 1.6) per degree, respectively, and daily attributable fractions were 0.8 (95% CI: 0.2, 1.3) and 1.1 (95% CI: 0.9, 1.4). The proximity of the latter coefficients to 1.0 provides evidence that most deaths found attributable to heat and cold in daily analyses were brought forward by at least 1 y. Estimates were broadly robust to alternative model assumptions.</P><P><B>Conclusions:</B></P><P>These results provide strong evidence that most deaths associated in daily analyses with heat and cold are displaced by at least 1 y. https://doi.org/10.1289/EHP1756</P>

EVOLUTION OF INTRINSIC SCATTER IN THE SFR-STELLAR MASS CORRELATION AT 0.5 < <i>z</i> < 3

Kurczynski, Peter,Gawiser, Eric,Acquaviva, Viviana,Bell, Eric F.,Dekel, Avishai,de Mello, Duilia F.,Ferguson, Henry C.,Gardner, Jonathan P.,Grogin, Norman A.,Guo, Yicheng,Hopkins, Philip F.,Koekemoer, American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.820 No.1

<P>We present estimates of intrinsic scatter in the star formation rate (SFR)-stellar mass (M-*) correlation in the redshift range 0.5 < z < 3.0 and in the mass range 10(7) < M-* < 10(11)M(circle dot). We utilize photometry in the Hubble Ultradeep Field (HUDF12) and Ultraviolet Ultra Deep Field (UVUDF) campaigns and CANDELS/GOODS-S and estimate SFR, M-* from broadband spectral energy distributions and the best-available redshifts. The maximum depth of the UDF photometry (F160W 29.9 AB, 5 sigma depth) probes the SFR-M-* correlation down to M-* similar to 10(7)M(circle dot), a factor of 10-100x lower in M-* than previous studies, and comparable to dwarf galaxies in the local universe. We find the slope of the SFR-M-* relationship to be near unity at all redshifts and the normalization to decrease with cosmic time. We find a moderate increase in intrinsic scatter with cosmic time from 0.2 to 0.4 dex across the epoch of peak cosmic star formation. None of our redshift bins show a statistically significant increase in intrinsic scatter at low mass. However, it remains possible that intrinsic scatter increases at low mass on timescales shorter than similar to 100 Myr. Our results are consistent with a picture of gradual and self-similar assembly of galaxies across more than three orders of magnitude in stellar mass from as low as 10(7)M(circle dot).</P>

Predicted temperature-increase-induced global health burden and its regional variability

Lee, Jae Young,Kim, Ho,Gasparrini, Antonio,Armstrong, Ben,Bell, Michelle L.,Sera, Francesco,Lavigne, Eric,Abrutzky, Rosana,Tong, Shilu,Coelho, Micheline de Sousa Zanotti Stagliorio,Saldiva, Paulo Hila Elsevier 2019 Environment international Vol.131 No.-

<P><B>Abstract</B></P> <P>An increase in the global health burden of temperature was projected for 459 locations in 28 countries worldwide under four representative concentration pathway scenarios until 2099. We determined that the amount of temperature increase for each 100 ppm increase in global CO<SUB>2</SUB> concentrations is nearly constant, regardless of climate scenarios. The overall average temperature increase during 2010–2099 is largest in Canada (1.16 °C/100 ppm) and Finland (1.14 °C/100 ppm), while it is smallest in Ireland (0.62 °C/100 ppm) and Argentina (0.63 °C/100 ppm). In addition, for each 1 °C temperature increase, the amount of excess mortality is increased largely in tropical countries such as Vietnam (10.34%p/°C) and the Philippines (8.18%p/°C), while it is decreased in Ireland (−0.92%p/°C) and Australia (−0.32%p/°C). To understand the regional variability in temperature increase and mortality, we performed a regression-based modeling. We observed that the projected temperature increase is highly correlated with daily temperature range at the location and vulnerability to temperature increase is affected by health expenditure, and proportions of obese and elderly population.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Future health burden with respect to CO<SUB>2</SUB> increase was projected in 28 countries. </LI> <LI> Future temperature and mortality were compared across locations. </LI> <LI> Daily temperature range determines the rate of temperature increase. </LI> <LI> Amount of health expenditure determines the vulnerability to temperature change. </LI> </UL> </P>

A study on the machinability of advanced arc PVD AlCrN‑coated tungsten carbide tools in drilling of CFRP/titanium alloy stacks

Dave Kim,Sam R. Swan,Bin He,Viktor Khominich,Eric Bell,Seok‑Woo Lee,Tae‑Gon Kim 한국탄소학회 2021 Carbon Letters Vol.31 No.3

This study aims to investigate the effect of an aluminum chromium nitride (AlCrN) coating on tool wear and hole quality in the conventional drilling process of carbon fiber-reinforced plastic (CFRP) composites, titanium alloy (Ti), and CFRP–Ti stack workpieces popular in the aerospace industry. The advanced arc plasma acceleration (APA) method of physical vapor deposition (PVD) was used for all AlCrN coatings. The drilling experiments were conducted with uncoated drills as well as AlCrN-coated drills. When drilling CFRP only, the AlCrN coating was removed at the drill cutting edges and the margin area, which suggests the carbon fibers abraded the coatings. When drilling Ti only, the AlCrN-coated drill mitigated the Ti adhesion formation, which resulted in less tool wear. In addition, hole quality for both CFRP and Ti was improved when the coating was used versus the uncoated tool. The machinability of CFRP–Ti stacks in the drilling process was improved by utilizing the advanced AlCrN coating on the WC tool in terms of drilling forces and hole quality parameters such as average hole size, average hole roundness, hole surface roughness, and Ti exit burr height.

THE EVOLUTION OF STAR FORMATION HISTORIES OF QUIESCENT GALAXIES

Pacifici, Camilla,Kassin, Susan A.,Weiner, Benjamin J.,Holden, Bradford,Gardner, Jonathan P.,Faber, Sandra M.,Ferguson, Henry C.,Koo, David C.,Primack, Joel R.,Bell, Eric F.,Dekel, Avishai,Gawiser, Er American Astronomical Society 2016 The Astrophysical Journal Vol.832 No.1

<P>Although there has been much progress in understanding how galaxies evolve, we still do not understand how and when they stop forming stars and become quiescent. We address this by applying our galaxy spectral energy distribution models, which incorporate physically motivated star formation histories (SFHs) from cosmological simulations, to a sample of quiescent galaxies at 0.2 < z < 2.1. A total of 845 quiescent galaxies with multi-band photometry spanning rest-frame ultraviolet through near-infrared wavelengths are selected from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) data set. We compute median SFHs of these galaxies in bins of stellar mass and redshift. At all redshifts and stellar masses, the median SFHs rise, reach a peak, and then decline to reach quiescence. At high redshift, we find that the rise and decline are fast, as expected, because the universe is young. At low redshift, the duration of these phases depends strongly on stellar mass. Low-mass galaxies (log(M*/M-circle dot) similar to 9.5) grow on average slowly, take a long time to reach their peak of star formation (greater than or similar to 4 Gyr), and then the declining phase is fast (less than or similar to 2 Gyr). Conversely, high-mass galaxies (log(M*/M-circle dot) similar to 11) grow on average fast (less than or similar to 2 Gyr), and, after reaching their peak, decrease the star formation slowly (greater than or similar to 3). These findings are consistent with galaxy stellar mass being a driving factor in determining how evolved galaxies are, with high-mass galaxies being the most evolved at any time (i.e., downsizing). The different durations we observe in the declining phases also suggest that low- and high-mass galaxies experience different quenching mechanisms, which operate on different timescales.</P>