Grassland carbon and nitrogen dynamics: effects of seasonal fire and clipping in a mixed-grass prairie of the southern great plains

Plant production and soil microbial biomass (SMB) in grassland ecosystems are linked by flows of carbon (C) and nitrogen (N) between the two groups of organisms. In native mixed grasslands of the southern Great Plains, these cycles are strongly influenced by climate. They may also be modulated by the timing and intensity of disturbances such as fire and clipping. We assessed the relative influence of climate and disturbance on plant community and soil C and N dynamics. Combined effects of fire and clipping were assessed in a 2x3 factorial design including spring fire and light clipping or continuous clipping. Seasonal fire effects were evaluated in a one-way analysis incorporating spring and fall fire in unclipped plots. Plant cover and biomass (by functional type), litter mass, SMB C and N, soil density fraction concentration and composition, soil organic C, total N, and inorganic N, soil temperature and moisture, soil respiration, and net N mineralization were measured at monthly intervals. C4 grasses were unaffected by fire or clipping, probably as a result of summer drought in both studyyears. Clipping reduced cover of C3 annual grasses but increased that of C3 perennials, resulting in no net change in C3 grass biomass. Fire did not affect C3 grass cover or biomass. Both fire and clipping reduced litter mass. This was reflected in seasonal declines in SMB C in fire treatments, suggesting that the primary input of microbial C in this ecosystem occurs by decomposition of current-season plant litter. Litter removal offers a single mechanism by which fire-induced increases in soil temperature and reductions in light soil density fraction concentration, soil moisture, and net N mineralization rates may be explained. Lack of treatment effects on soil respiration rates suggest that plant roots represent an important component of the plant-soil C cycle, not quantified in this research. Overall, treatment effects were relatively minor compared to seasonal climate-related changes in response variables, particularly in light of repeated summer drought

Eradication of two incursions of the Red Imported Fire Ant in Queensland, Australia

Of the five known incursions of the highly invasive Red Imported Fire Ant in Australia, two are regarded to have been eradicated. As treatment efforts continue, and the programme evolves and new tools become available, eradication is still considered to be feasible for the remaining Red Imported Fire Ant populations with long-term commitment and support

Drug Testing in Juvenile Diversion Programs

Evidence-Based Practices Brief #3. According to the Risk-Needs-Responsivity (RNR) framework1,2, juvenile diversion programs that individualize diversion plans will be more effective at reducing recidivism because the juvenile’s risk level and needs are being targeted.3 To follow RNR, programs should assess youth with a validated assessment tool and then match youth to services based on the risks and needs presented by the assessment tool

Reliability and Predictive Validity of Screener/Assessment Tools in Nebraska Juvenile Diversion

Juvenile diversion is offered in most counties throughout Nebraska to eligible youth; and although state guidelines require the use of a screening or assessment tool, the tools utilized are not standardized or uniform statewide. This report quantifies whether the various tools are being reliably administered and are effectively predicting diversion completion and future system involvement. The Juvenile Justice Institute gathered item-level risk/needs screener and assessment data from all juvenile diversion programs receiving Community-based Aid (CBA) funds. Overall, 3,916 youth were assessed for a juvenile diversion program between July 1st, 2015 and June 30th, 2017. The Youth Level of Service Inventory/Case Management Inventory (YLS) comprised the largest number of completed assessments (n = 2,193), followed by the Nebraska Youth Screen (NYS; n = 1,512), and the Arizona Risk-Needs Assessment (ARNA; n = 211). First, we tested the reliability of each tool, which is how well it is consistently performing at predicting risk (i.e., less error in measurement). Reliability analyses revealed the YLS/CMI had the strongest internal consistency of the three measures, which means the items are grouped well together to measure the construct (i.e., risk level). The items within the NYS, however, demonstrated the strongest item-total correlations, which means these items were most related to the overall construct (i.e., risk level). Both the NYS and ARNA had poor internal consistency. Second, we performed Receiver Operating Curve (ROC) analyses to determine the predictive validity of each tool, utilizing both unsuccessful discharge from diversion and future system involvement as outcomes. Results revealed all three tools had predictive validity for unsuccessful diversion completion with large effect sizes (i.e., measure of strength of the relationship). Furthermore, while all three tools demonstrated predictive validity for future system involvement with small to moderate effect sizes, when we tested predictive validity by both gender and race/ethnicity, only the YLS accurately predicted future system involvement for girls, none of the tools accurately predicted future system involvement for Black/African American youth, and only the ARNA accurately predicted future system involvement for Hispanic youth. While it is always recommended to screen and/or assess youth, the tools currently being utilized in Nebraska juvenile diversion programs are not reliably and validly measuring risk for all youth assessed. The most problematic items within each tool were those relating to prior convictions or prior contacts with the legal system. Because this is a diversion population, presumably with little to no prior juvenile justice system involvement, these items poorly capture risk in this population, which in turn contributes to lower reliability and predictive validity. While these findings do not provide definitive results for us to whole-heartedly recommend a tool for juvenile diversion programs at this time, our recommendation is to explore creating/utilizing a risk assessment tool that removes items that measure previous legal system involvement or norming current tools without those items. Future research and practice should continue to explore gender and racial/ethnic differences within youth assessment

Annual Report FY 16-17

Evidence-Based Nebraska Recognizing that unnecessary formal involvement in the juvenile justice system may be contrary to the best interests and well-being of juveniles, the state of Nebraska established funds through the Community-based Juvenile Services Aid (CBA) Program for counties and tribes to use for developing programs and services (Neb. Rev. Stat. § 43-2404.02). The purpose of the CBA fund is to assist counties with developing intervention and prevention activities “designed to serve juveniles and deter involvement in the formal juvenile justice system” (Neb. Rev. Stat. § 43-2404.02 (b)). A total of 71 counties and two tribes in Nebraska received funding in fiscal year 2016-2017 (FY 16/17). In some instances, counties join multi-county groups with a single lead county that manages the grant. In FY 16/17 there were 10 multi-county groups. During this time, there were approximately 243 CBA-funded programs (including system improvement programs that do not work directly with youth); however, the number of programs may fluctuate throughout the year due to subgrant adjustments, carry over funds from the previous year, or late program registration

Formation of Multiple Populations in Globular Clusters: Another Possible Scenario

While chemical composition spreads are now believed to be a universal characteristic of globular clusters (GCs), not all of them present multiple populations in their color-magnitude diagrams (CMDs). Here we present a new scenario for the formation of GCs, in an attempt to qualitatively explain this otherwise intriguing observational framework. Our scenario divides GCs into three groups, depending on the initial mass (M_I) of the progenitor structure (PS), as follows. i) Massive PSs can retain the gas ejected by massive stars, including the ejecta of core-collapse SNe. ii) Intermediate-mass PSs can retain at least a fraction of the fast winds of massive stars, but none of the core-collapse SNe ejecta. iii) Low-mass PSs can only retain the slow winds of intermediate-mass stars. Members of the first group would include omega Centauri (NGC 5139), M54 (NGC 6715), M22 (NGC 6656), and Terzan 5, whereas NGC 2808 (and possibly NGC 2419) would be members of the second group. The remaining GCs which only present a spread in light elements, such as O and Na, would be members of the third group. According to our scenario, the different components in omega Cen should not display a sizeable spread in age. We argue that this is consistent with the available observations. We give other simple arguments in favor of our scenario, which can be described in terms of two main analytical relations: i) Between the actual observed ratio between first and second generation stars (R_SG^FG) and the fraction of first generation stars that have been lost by the GC (S_L); and ii) Between S_L and M_I. We also suggest a series of future improvements and empirical tests that may help decide whether the proposed scenario properly describes the chemical evolution of GCs.Comment: Accepted for publication in Astronomy and Astrophysic

Interplay between pleiotropy and secondary selection determines rise and fall of mutators in stress response

Dramatic rise of mutators has been found to accompany adaptation of bacteria in response to many kinds of stress. Two views on the evolutionary origin of this phenomenon emerged: the pleiotropic hypothesis positing that it is a byproduct of environmental stress or other specific stress response mechanisms and the second order selection which states that mutators hitchhike to fixation with unrelated beneficial alleles. Conventional population genetics models could not fully resolve this controversy because they are based on certain assumptions about fitness landscape. Here we address this problem using a microscopic multiscale model, which couples physically realistic molecular descriptions of proteins and their interactions with population genetics of carrier organisms without assuming any a priori fitness landscape. We found that both pleiotropy and second order selection play a crucial role at different stages of adaptation: the supply of mutators is provided through destabilization of error correction complexes or fluctuations of production levels of prototypic mismatch repair proteins (pleiotropic effects), while rise and fixation of mutators occur when there is a sufficient supply of beneficial mutations in replication-controlling genes. This general mechanism assures a robust and reliable adaptation of organisms to unforeseen challenges. This study highlights physical principles underlying physical biological mechanisms of stress response and adaptation