The Suess effect in Fiji coral δ13C and its potential as a tracer of anthropogenic CO2 uptake

In the context of increasing anthropogenic CO2 emissions, determining the rate of oceanic CO2 uptake is of high interest. Centennial-scale changes in δ13C of the surface water dissolved inorganic carbon (DIC) reservoir have been shown to be influenced by the carbon isotopic composition of atmospheric CO2. However, the availability of direct oceanic δ13C measurements is limited and methods for reconstructing past δ13C variability of the oceanic DIC are needed. Geochemical reconstructions of DIC variability can help in understanding how the ocean has reacted to historical changes in the carbon cycle. This study explores the potential of using temporal variations in δ13C measured in five Fijian Porites corals for reconstructing oceanic δ13C variability. A centennial-scale decreasing δ13C trend is observed in these Fiji corals. Other studies have linked similar decreasing δ13C trends to anthropogenic changes in the atmospheric carbon reservoir (the “13C Suess effect”). We conclude that solar irradiance is the factor influencing the δ13C cycle on a seasonal scale, however it is not responsible for the centennial-scale decreasing δ13C trend. In addition, variations in skeletal extension rate are not found to account for centennial-scale δ13C variability in these corals. Rather, we found that water depth at which a Fijian Porites colony calcifies influences both δ13C and extension rate mean values. The water depth-δ13C relationship induces a dampening effect on the centennial-scale decreasing δ13C trend. We removed this “water depth effect” from the δ13C composite, resulting in a truer representation of δ13C variability of the Fiji surface water DIC (δ13CFiji-DIC). The centennial-scale trend in this Fiji coral composite δ13CFiji-DIC time-series shares similarities with atmospheric δ13CCO2, implicating the 13C Suess effect as the source of the this coral δ13C trend. Additionally, our study finds that the δ13C variability between the atmosphere and the ocean in this region is not synchronous; the coral δ13C response is delayed by ~ 10 years. This agrees with the previously established model of isotopic disequilibrium between atmospheric δ13CCO2 and oceanic surface water DIC

Clogging by sieving in microchannels: Application to the detection of contaminants in colloidal suspensions

We report on a microfluidic method that allows measurement of a small concentration of large contaminants in suspensions of solid micrometer-scale particles. To perform the measurement, we flow the colloidal suspension through a series of constrictions, i.e. a microchannel of varying cross-section. We show and quantify the role of large contaminants in the formation of clogs at a constriction and the growth of the resulting filter cake. By measuring the time interval between two clogging events in an array of parallel microchannels, we are able to estimate the concentration of contaminants whose size is selected by the geometry of the microfluidic device. This technique for characterizing colloidal suspensions offers a versatile and rapid tool to explore the role of contaminants on the properties of the suspensions

After-School Connectedness, Racial–Ethnic Identity, Affirmation, and Problem Behaviors

After-school programs are potential contexts that may promote positive youth development (PYD) and reduce problem behaviors among African American children. One way after-school programs may be associated with reduced problem behaviors is by fostering an affirming sense of identity. Prior research on racial–ethnic identity among African American children and adolescents has shown that a positive and affirming sense of identity is related to less maladaptive coping, yet little is known about how after-school programs may foster an affirming sense of identity and lead to reduced problem behaviors. The current study adds to this discourse by investigating how children’s connection to staff and peers in after-school settings is associated with racial–ethnic identity (as measured by racial–ethnic affirmation) and reduced problem behaviors. Participants were 186 African American children ages 7–11 (M = 8.44; SD = 1.10) who completed surveys in the LEGACY Together Afterschool research project. Data were collected at 55 community-based after-school programs. Results indicated that positive racial–ethnic affirmation mediated the association between after-school connectedness and problem behaviors, such that childreport of connectedness—that is feeling safe and happy in the after-school programs—was directly related to positive racial–ethnic identity and indirectly to reduced problem behaviors. These findings underscore the importance of supportive after-school programs that encourage meaningful interactions among staff and children that are nurturing and affirming to children’s identities

Optical activation of germanium plasmonic antennas in the mid-infrared

Impulsive interband excitation with femtosecond near-infrared pulses establishes a plasma response in intrinsic germanium structures fabricated on a silicon substrate. This direct approach activates the plasmonic resonance of the Ge structures and enables their use as optical antennas up to the mid-infrared spectral range. The optical switching lasts for hundreds of picoseconds until charge recombination redshifts the plasma frequency. The full behavior of the structures is modeled by the electrodynamic response established by an electron-hole plasma in a regular array of antennas

Application of Time Domain Reflectometers in Urban Settings

Time domain reflectometers (TDRs) are in-situ monitoring probes that record soil moisture content when calibrated to a particular soil. Typically TDRs are used in agricultural settings, but this technology may also be applied to urban soils. The Urban Watershed Management Branch located at the Edison Environmental Center (EEC) has been exploring the use of TDRs as a way to monitor stormwater infiltration practices. TDRs are installed in pilot- and full-scale bioretention units (e.g., rain gardens). The TDRs are capable of measuring soil moisture and sensing the wetting front as the stormwater infiltrates through the planting media and into the native soil. Recently, a new permeable pavement parking lot was constructed at the EEC. This parking lot was designed for long-term monitoring and included the installation of TDRs, both in the crushed concrete storage layer and in the underlying soil. Early indications suggest that while this novel application of TDRs in crushed concrete may not provide calibrated moisture content, wetting fronts correspond to those of the TDRs in soils. Extensive bench-scale testing was performed in crushed concrete prior to the permanent installation below the paved surfaces as a proof of concept test. Application of this technology may be suitable to urban areas that are interested in modifying tree pit design, controlling stormwater through rain gardens and porous pavements, or using manufactured or engineered soils, and seek or require supporting data that water is infiltrating and available to plants

Immunotherapy: Is it different for sarcomas?

The Janus-faced roles of macrophages in cancer imply both tumor-suppressive and -stimulating actions of these innate immune cells. Whereas the balance is toward tumor promotion in most epithelial cancers, we have recently shown that osteosarcoma metastasis seems to be inhibited by macrophages. Here we discuss the possible mechanism of this observation

The Role of Ethnic Identity in Interventions to Promote Positive Adolescent Development

This paper addresses the role of ethnic identity in child development. We report on two school-based interventions with a focus on strengthening the ethnic identity of girls, one with a Hispanic population and one with an African American population. We also report on a study investigating whether parental ethnic identity plays a mediating role in African American parenting styles. The results of each study were non-significant in relation to their specific hypotheses regarding ethnic identity. We discuss the implications of these non-significant findings, particularly given that the two interventions were conducted in minority-majority communities

n-Ge on Si for Mid-Infrared Plasmonic Sensors

The detection and amplification of molecular absorption lines from a mustard gas simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. Approaches to integrated sensors will be presented along with a review of n-Ge compared to other mid-infrared plasmonic materials

The Role of Ethnic Identity in Interventions to Promote Positive Adolescent Development

This paper addresses the role of ethnic identity in child development. We report on two school-based interventions with a focus on strengthening the ethnic identity of girls, one with a Hispanic population and one with an African American population. We also report on a study investigating whether parental ethnic identity plays a mediating role in African American parenting styles. The results of each study were non-significant in relation to their specific hypotheses regarding ethnic identity. We discuss the implications of these non-significant findings, particularly given that the two interventions were conducted in minority-majority communities