2,917 research outputs found
Gold( i )-catalyzed addition of aldehydes to cyclopropylidene bearing 6-aryl-1,5-enynes
A diastereoselective, gold-catalyzed cascading cycloisomerization of alkylidene cyclopropane bearing 1,5-enynes that terminates in a cyclo-addition of aldehydes has been developed
Promoting CâC Bond Coupling of Benzyne and Methyl Ligands in Electron-Deficient (triphos)PtâCH 3 + Complexes
In situ generated benzyne reacts at room temperature with (triphos)Pt-CH3 (+) to form a five-coordinate Ï-complex (2) that is isolable and stable in solution. Thermolysis of 2 at 60 °C generates (triphos)Pt(o-tolyl)(+) (3), which is the product of formal migratory insertion of CH3 (-) onto the coordinated benzyne. The reaction of 2 with the acid Ph2NH2 (+) yields toluene at room temperature over the course of 8 h, while the same reaction with 3 only proceeds to 40% conversion over 2 days. These data indicate that the protonolysis of 2 does not proceed by CH3 migration onto benzyne to form 3 followed by protodemetalation. Instead, the data suggest either that protonation of 2 is first and is followed by H migration to yield a Pt(IV)Ph(Me) dication or that this latter species is generated by direct protonolysis of coordinated benzyne prior to reductive elimination of toluene
'Against the World': Michael Field, female marriage and the aura of amateurism'
This article considers the case of Katherine Bradley and Edith Cooper, an aunt and niece who lived and wrote together as âMichael Fieldâ in the fin-de-siĂšcle Aesthetic movement. Bradleyâs bold statement that she and Cooper were âcloser marriedâ than the Brownings forms the basis for a discussion of their partnership in terms of a âfemale marriageâ, a union that is reflected, as I will argue, in the pages of their writings. However, Michael Fieldâs exclusively collaborative output, though extensive, was no guarantee for success. On the contrary, their case illustrates the notion, valid for most products of co-authorship, that the jointly written work is always surrounded by an aura of amateurism. Since collaboration defied the ingrained notion of the author as the solitary producer of his or her work, critics and readers have time and again attempted to âparseâ the collaboration by dissecting the co-authored work into its constituent halves, a treatment that the Fields too failed to escape
Implementation of a Shared Data Repository and Common Data Dictionary for Fetal Alcohol Spectrum Disorders Research
Many previous attempts by fetal alcohol spectrum disorders researchers to compare data across multiple prospective and retrospective human studies have failed due to both structural differences in the collected data as well as difficulty in coming to agreement on the precise meaning of the terminology used to describe the collected data. Although some groups of researchers have an established track record of successfully integrating data, attempts to integrate data more broadly amongst different groups of researchers have generally faltered. Lack of tools to help researchers share and integrate data has also hampered data analysis. This situation has delayed improving diagnosis, intervention, and treatment before and after birth. We worked with various researchers and research programs in the Collaborative Initiative on Fetal Alcohol Spectrum Disorders (CI-FASD) to develop a set of common data dictionaries to describe the data to be collected, including definitions of terms and specification of allowable values. The resulting data dictionaries were the basis for creating a central data repository (CI-FASD Central Repository) and software tools to input and query data. Data entry restrictions ensure that only data which conform to the data dictionaries reach the CI-FASD Central Repository. The result is an effective system for centralized and unified management of the data collected and analyzed by the initiative, including a secure, long-term data repository. CI-FASD researchers are able to integrate and analyze data of different types, collected using multiple methods, and collected from multiple populations, and data are retained for future reuse in a secure, robust repository
Implementation of a Distributed Architecture for Managing Collection and Dissemination of Data for Fetal Alcohol Spectrum Disorder
We implemented a distributed system for management of data for an international collaboration studying Fetal Alcohol Spectrum Disorders (FASD). Subject privacy was protected, researchers without dependable Internet access were accommodated, and researchersâ data were shared globally. Data dictionaries codified the nature of the data being integrated, data compliance was assured through multiple consistency checks, and recovery systems provided a secure, robust, persistent repository. The system enabled new types of science to be done, using distributed technologies that are expedient for current needs while taking useful steps towards integrating the system in a future grid-based cyberinfrastructure. The distributed architecture, verification steps, and data dictionaries suggest general strategies for researchers involved in collaborative studies, particularly where data must be de-identified before being shared. The system met both the collaborationâs needs and the NIH Roadmapâs goal of wide access to databases that are robust and adaptable to researchersâ needs
Elimination of a group II intron from a plastid gene causes a mutant phenotype
Group II introns are found in bacteria and cell organelles (plastids, mitochondria) and are thought to represent the evolutionary ancestors of spliceosomal introns. It is generally believed that group II introns are selfish genetic elements that do not have any function. Here, we have scrutinized this assumption by analyzing two group II introns that interrupt a plastid gene (ycf3) involved in photosystem assembly. Using stable transformation of the plastid genome, we have generated mutant plants that lack either intron 1 or intron 2 or both. Interestingly, the deletion of intron 1 caused a strong mutant phenotype. We show that the mutants are deficient in photosystem I and that this deficiency is directly related to impaired ycf3 function. We further show that, upon deletion of intron 1, the splicing of intron 2 is strongly inhibited. Our data demonstrate that (i) the loss of a group II intron is not necessarily phenotypically neutral and (ii) the splicing of one intron can depend on the presence of another
Status of the Fritz Haber Institute THz FEL
The THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4 m long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2 m long cavity with a 1-d waveguide for the optical mode is used for the far-IR. A key aspect of the accelerator performance is low longitudinal emittance, < 50 keV-psec, at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the FHI in October 2011 and we will describe progress in the commissioning of this device. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described
Using ice core measurements from Taylor Glacier, Antarctica, to calibrate in situ cosmogenic 14 C production rates by muons
Cosmic rays entering the Earthâs atmosphere produce showers of secondary particles such as protons, neutrons, and muons. The interaction of these particles with oxygen-16 (16O) in minerals such as ice and quartz can produce carbon-14 (14C). In glacial ice, 14C is also incorporated through trapping of 14C-containing atmospheric gases (14CO2, 14CO, and 14CH4). Understanding the production rates of in situ cosmogenic 14C is important to deconvolve the in situ cosmogenic and atmospheric 14C signals in ice, both of which contain valuable paleoenvironmental information. Unfortunately, the in situ 14C production rates by muons (which are the dominant production mechanism at depths of > 6m solid ice equivalent) are uncertain. In this study, we use measurements of in situ 14C in ancient ice (> 50 ka) from the Taylor Glacier, an ablation site in Antarctica, in combination with a 2D ice flow model to better constrain the compound-specific rates of 14C production by muons and the partitioning of in situ 14C between CO2, CO, and CH4. Our measurements show that 33.7% (11.4%; 95% confidence interval) of the produced cosmogenic 14C forms 14CO and 66.1% (11.5%; 95% confidence interval) of the produced cosmogenic 14C forms 14CO2. 14CH4 represents a very small fraction (< 0.3%) of the total. Assuming that the majority of in situ muogenic 14C in ice forms 14CO2, 14CO, and 14CH4, we also calculated muogenic 14C production rates that are lower by factors of 5.7 (3.6â13.9; 95% confidence interval) and 3.7 (2.0â11.9; 95% confidence interval) for negative muon capture and fast muon interactions, respectively, when compared to values determined in quartz from laboratory studies (Heisinger et al., 2002a, b) and in a natural setting (Lupker et al., 2015). This apparent discrepancy in
muogenic 14C production rates in ice and quartz currently lacks a good explanation and requires further investigation
Kinetics of progenitor hemopoetic stem cells in sepsis: Correlation with patients survival?
BACKGROUND: Current theories underline the crucial role of pro-inflammatory mediators produced by monocytes for the pathogenesis of sepsis. Since monocytes derive from progenitor hemopoetic cells, the kinetics of stem cells was studied in peripheral blood of patients with sepsis. METHODS: Blood was sampled from 44 patients with septic syndrome due to ventilator-associated pneumonia on days 1, 3, 5 and 7 upon initiation of symptoms. Concentrations of tumour necrosis factor-alpha (TNFα), interleukin (IL)-6, IL-8 and G-CSF were estimated by ELISA. CD34/CD45 cells were determined after incubation with anti-CD45 FITC and anti-CD34 PE monocloncal antibodies and flow cytometric analysis. Samples from eight healthy volunteers served as controls. RESULTS: Median of CD34/CD45 absolute count of controls was 1.0/Όl. Respective values of the total study population were 123.4, 112.4, 121.5 and 120.9/Όl on days 1, 3, 5 and 7 (p < 0.0001 compared to controls). Positive correlations were found between the absolute CD34/CD45 count and the absolute monocyte count on days 1, 5 and 7. Survival was prolonged among patients with less than 310/Όl CD34/CD45 cells on day 1 compared to those with more than 310/Όl of CD34/CD45 cells (p: 0.022). Hazard ratio for death due to sepsis was 5.47 (p: 0.039) for CD34/CD45 cells more than 310/Όl. Median IL-6 on day 1 was 56.78 and 233.85 pg/ml respectively for patients with less than 310/Όl and more than 310/Όl CD34/CD45 cells (p: 0.021). CONCLUSION: Stem cells are increased in peripheral blood over all days of follow-up compared to healthy volunteers. Patients with counts on day 1 less than 310/Όl are accompanied by increased survival compared to patients with more than 310/Όl
Childhood cancer burden: a review of global estimates.
5-year net survival of children and adolescents diagnosed with cancer is approximately 80% in many high-income countries. This estimate is encouraging as it shows the substantial progress that has been made in the diagnosis and treatment of childhood cancer. Unfortunately, scarce data are available for low-income and middle-income countries (LMICs), where nearly 90% of children with cancer reside, suggesting that global survival estimates are substantially worse in these regions. As LMICs are undergoing a rapid epidemiological transition, with a shifting burden from infectious diseases to non-communicable diseases, cancer care for all ages has become a global focus. To improve outcomes for children and adolescents diagnosed with cancer worldwide, an accurate appraisal of the global burden of childhood cancer is a necessary first step. In this Review, we analyse four studies of the global cancer burden that included data for children and adolescents. Each study used various overlapping and non-overlapping statistical approaches and outcome metrics. Moreover, to provide guidance on improving future estimates of the childhood global cancer burden, we propose several recommendations to strengthen data collection and standardise analyses. Ultimately, these data could help stakeholders to develop plans for national and institutional cancer programmes, with the overall aim of helping to reduce the global burden of cancer in children and adolescents
- âŠ