Three point boundary value problems for ordinary differential equations, uniqueness implies existence

We consider a family of three point n − 2, 1, 1 conjugate boundary value problems for nth order nonlinear ordinary differential equations and obtain conditions in terms of uniqueness of solutions imply existence of solutions. A standard hypothesis that has proved effective in uniqueness implies existence type results is to assume uniqueness of solutions of a large family of n−point boundary value problems. Here, we replace that standard hypothesis with one in which we assume uniqueness of solutions of large families of two and three point boundary value problems. We then close the paper with verifiable conditions on the nonlinear term that in fact imply global uniqueness of solutions of the large family of three point boundary value problems

Recent advances in biomedical applications of accelerator mass spectrometry

After publication of our article, it was noted that we inadvertently failed to include the complete list of authors. The full list, including co-authors, has now been added and the Authors' contributions and Competing interests sections modified accordingly

Understanding inclusion in collaborative governance: a mixed methods approach

Who should be included in collaborative governance and how they should be included is an important topic, though the dynamics of inclusion are not yet well understood. We propose a conceptual model to shape the empirical analysis of what contributes to inclusion in collaborative processes. We propose that incentives, mutual interdependence and trust are important preconditions of inclusion, but that active inclusion management also matters a great deal. We also hypothesize that inclusion is strategic, with ‘selective activation’ of participants depending on functional and pragmatic choices. Drawing on cases from the Collaborative Governance Case Databank, we used a mixed method approach to analyse our model. We found support for the model, and particularly for the central importance of active inclusion management.Fil: Ansell, Christopher. University of California at Berkeley; Estados UnidosFil: Doberstein, Carey. University of British Columbia; CanadáFil: Henderson, Hayley. The Australian National University; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Estudios Urbanos y Regionales; ArgentinaFil: Siddiki, Saba. Syracuse University; Estados UnidosFil: ‘t Hart, Paul. Utrecht University; Países Bajo

Persistence of pharmaceutical compounds and other organic wastewater contaminants in a conventional drinking-water-treatment plant

In a study conducted by the US Geological Survey and the Centers for Disease Control and Prevention, 24 water samples were collected at selected locations within a drinking-water-treatment (DWT) facility and from the two streams that serve the facility to evaluate the potential for wastewater-related organic contaminants to survive a conventional treatment process and persist in potable-water supplies. Stream-water samples as well as samples of raw, settled, filtered, and finished water were collected during low-flow conditions, when the discharge of effluent from upstream municipal sewage-treatment plants accounted for 37–67% of flow in stream 1 and 10–20% of flow in stream 2. Each sample was analyzed for 106 organic wastewater-related contaminants (OWCs) that represent a diverse group of extensively used chemicals.Forty OWCs were detected in one or more samples of stream water or raw-water supplies in the treatment plant; 34 were detected in more than 10% of these samples. Several of these compounds also were frequently detected in samples of finished water; these compounds include selected prescription and non-prescription drugs and their metabolites, fragrance compounds, flame retardants and plasticizers, cosmetic compounds, and a solvent. The detection of these compounds suggests that they resist removal through conventional water-treatment processes. Other compounds that also were frequently detected in samples of stream water and rawwater supplies were not detected in samples of finished water; these include selected prescription and non-prescription drugs and their metabolites, disinfectants, detergent metabolites, and plant and animal steroids. The non-detection of these compounds indicates that their concentrations are reduced to levels less than analytical detection limits or that they are transformed to degradates through conventional DWT processes. Concentrations of OWCs detected in finished water generally were low and did not exceed Federal drinking-water standards or lifetime health advisories, although such standards or advisories have not been established for most of these compounds. Also, at least 11 and as many as 17 OWCs were detected in samples of finished water. Drinking-water criteria currently are based on the toxicity of individual compounds and not combinations of compounds. Little is known about potential human-health effects associated with chronic exposure to trace levels of multiple OWCs through routes such as drinking water. The occurrence in drinking-water supplies of many of the OWCs analyzed for during this study is unregulated and most of these compounds have not been routinely monitored for in the Nation’s source- or potable-water supplies. This study provides the first documentation that many of these compounds can survive conventional water-treatment processes and occur in potable-water supplies. It thereby provides information that can be used in setting research and regulatory priorities and in designing future monitoring programs. The results of this study also indicate that improvements in water-treatment processes may benefit from consideration of the response of OWCs and other trace organic contaminants to specific physical and chemical treatments

Incorporation of extracellular 8-oxodG into DNA and RNA requires purine nucleoside phosphorylase in MCF-7 cells

7,8-Dihydro-8-oxo-2′-deoxyguanosine (8-oxodG) is a well-known marker of oxidative stress. We report a mechanistic analysis of several pathways by which 8-oxodG is converted to nucleotide triphosphates and incorporated into both DNA and RNA. Exposure of MCF-7 cells to [14C]8-oxodG combined with specific inhibitors of several nucleotide salvage enzymes followed with accelerator mass spectrometry provided precise quantitation of the resulting radiocarbon-labeled species. Concentrations of exogenously dosed nucleobase in RNA reached one per 106 nucleotides, 5–6-fold higher than the maximum observed in DNA. Radiocarbon incorporation into DNA and RNA was abrogated by Immucillin H, an inhibitor of human purine nucleoside phosphorylase (PNP). Inhibition of ribonucleotide reductase (RR) decreased the radiocarbon content of the DNA, but not in RNA, indicating an important role for RR in the formation of 8-oxodG-derived deoxyribonucleotides. Inhibition of deoxycytidine kinase had little effect on radiocarbon incorporation in DNA, which is in contrast to the known ability of mammalian cells to phosphorylate dG. Our data indicate that PNP and RR enable nucleotide salvage of 8-oxodG in MCF-7 cells, a previously unrecognized mechanism that may contribute to mutagenesis and carcinogenesis

Deterministic delivery of externally cold and precisely positioned single molecular ions

We present the preparation and deterministic delivery of a selectable number of externally cold molecular ions. A laser cooled ensemble of Mg^+ ions subsequently confined in several linear Paul traps inter-connected via a quadrupole guide serves as a cold bath for a single or up to a few hundred molecular ions. Sympathetic cooling embeds the molecular ions in the crystalline structure. MgH^+ ions, that serve as a model system for a large variety of other possible molecular ions, are cooled down close to the Doppler limit and are positioned with an accuracy of one micrometer. After the production process, severely compromising the vacuum conditions, the molecular ion is efficiently transfered into nearly background-free environment. The transfer of a molecular ion between different traps as well as the control of the molecular ions in the traps is demonstrated. Schemes, optimized for the transfer of a specific number of ions, are realized and their efficiencies are evaluated. This versatile source applicable for broad charge-to-mass ratios of externally cold and precisely positioned molecular ions can serve as a container-free target preparation device well suited for diffraction or spectroscopic measurements on individual molecular ions at high repetition rates (kHz).Comment: 11 pages, 8 figure

Dataset associated with "Seeking congruity for agentic women: a longitudinal examination of college women's persistence in STEM"

Those interested in using these data are encouraged to contact Dr. Paul Hernandez ([email protected]) and Dr. Emily Fischer ([email protected]) for more information. Data Contacts: Paul R. Hernandez (primary), [email protected], 979-464-9229 Emily V. Fischer, [email protected], 970-491-8587.Survey data were collected via the online Qualtrics survey system twice yearly in the fall and spring semesters from fall 2015 through spring 2019. This repository contains the data file associated with all surveys utilized in the analyses presented in this research article.Format of Data Files: Data files are in .csv format. Files can be opened by most software (e.g., Notepad, WordPad, Excel) – anything that can read a comma delimited ASCII text file. Here, the file name is "Dataset." In addition, a codebook accompanies the data file. The codebook contains the variable names, variable labels, and value labels for all variables contained within the "Dataset.csv" file.An abundance of literature has examined barriers to women's equal representation in science, technology, engineering, and math (STEM) fields, with many studies showing that STEM fields are not perceived to afford communal goals, a key component of women's interest in future careers. Using Goal Congruity Theory as a framework, we tested the longitudinal impact of perceptions of STEM career goal affordances, communal and agentic goals, and their congruity on persistence in science from the second through fourth years of college among women in STEM majors. We found that women's intent to persist in science were highest in fall of their second year, that persistence intentions exhibited a sharp decline, and that eventually leveled off by their fourth year of college. This pattern was moderated by perceptions of agentic affordances in STEM, such that women with higher perceptions of agentic affordances experienced smaller declines. Similar to prior research, we found that higher perceptions of communal goal affordances in STEM consistently predicted higher persistence intentions. Finally, we found an agentic goal-affordance congruity interaction, such that higher perceptions of agentic affordances in STEM predicted higher persistence intentions; however, the positive relationship was stronger for women with higher agentic goals. We conclude that because STEM fields are stereotyped as affording agentic goals, women who identify interest in a STEM major during their first year of college may be drawn to these fields for this reason, and may benefit from perceptions that STEM affords both communal and agentic goals.Funding for this work was provided by the National Science Foundation through grant number DUE- 1431795, DUE-1431823, and DUE-1460229

Influence of nuclear structure on sub-barrier hindrance in Ni+Ni fusion

Fusion-evaporation cross sections for $^{64}$Ni+$^{64}$Ni have been measured down to the 10 nb level. For fusion between two open-shell nuclei, this is the first observation of a maximum in the $S$-factor, which signals a strong sub-barrier hindrance. A comparison with the $^{58}$Ni+$^{58}$Ni, $^{58}$Ni+$^{60}$Ni, and $^{58}$Ni+$^{64}$Ni systems indicates a strong dependence of the energy where the hindrance occurs on the stiffness of the interacting nuclei.Comment: Submitted to Phys. Rev. Lett. 4 pages, 3 figure

Heterogeneities in Supercooled liquids: A Density Functional Study

A metastable state, characterized by a low degree of mass localization is identified using Density Functional Theory. This free energy minimum, located through the proper evaluation of the competing terms in the free energy functional, is independent of the specific form of the DFT used. Computer simulation results on particle motion indicate that this heterogeneous state corresponds to the supercooled state.Comment: 10 pages, 6 figure