78 research outputs found
CN− Secondary Ions Form by Recombination as Demonstrated Using Multi-Isotope Mass Spectrometry of 13C- and 15N-Labeled Polyglycine
We have studied the mechanism of formation CN− secondary ions under Cs+ primary ion bombardment. We have synthesized 13C and 15N labeled polyglycine samples with the distance between the two labels and the local atomic environment of the 13C label systematically varied. We have measured four masses in parallel: 12C, 13C, and two of 12C14N, 13C14N, 12C15N, and 13C15N. We have calculated the 13C/12C isotope ratio, and the different combinations of the CN isotope ratios (27CN/26CN, 28CN/27CN, and 28CN/26CN). We have measured a high 13C15N − secondary ion current from the 13C and 15N labeled polyglycines, even when the 13C and 15N labels are separated. By comparing the magnitude of the varied combinations of isotope ratios among the samples with different labeling positions, we conclude the following: CN− formation is in large fraction due to recombination of C and N; the CO double bond decreases the extent of CN− formation compared to the case where carbon is singly bonded to two hydrogen atoms; and double-labeling with 13C and 15N allows us to detect with high sensitivity the molecular ion 13C15N−
A New Paradigm to Address Bid Protests
Sponsored Report (for Acquisition Research Program)distribution unlimited.The goal of this study is to offer senior decision-makers a useful framework to evaluate, articulate, and recommend modifications of the government''s bid protest policy to improve procurement outcomes. Most countries allow disappointed bidders to protest public procurement decisions as an oversight mechanism to minimize fraud and errors by procurement officials. The expectation is that allowing bid protests increases transparency and accountability and encourages competition, reducing the cost of public purchases. A key contribution of this study is to add an economics dimension to a bid protest process that is mostly thought of in legal terms. The economics approach suggests firms are likely to use the protest process strategically to improve their competitive bargaining position and will be equally strategic in their decision to protest an award. The conclusion is that a firm''s responsibility to its shareholders can lead it to undertake protests for reasons substantially different from, and fundamentally opposed to, the government''s objectives. The economics approach suggests minimizing the risk of protests that result in cost overruns, schedule delays, and performance gaps, while preserving the benefits offered by protests to promote competition and ensure the integrity, transparency, and accountability of the procurement process. Adopting an economics perspective reveals two other crucial insights: firms can exploit protests to extract concessions (Fed Mail), and risk-averse officials can overreact in attempts to achieve protest-proof procurements (Buy-offs). In recognizing costs as well as benefits of a protest system, the economics approach invites a review of alternative portfolios of governance mechanisms that complement bid protests (internal audits, external audits, independent investigations, alternative dispute resolution, increased training and incentives, etc.), to improve procurement outcomes.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited
Core Alzheimer’s disease cerebrospinal fluid biomarker assays are not affected by aspiration or gravity drip extraction methods
Background
CSF biomarkers are well-established for routine clinical use, yet a paucity of comparative assessment exists regarding CSF extraction methods during lumbar puncture. Here, we compare in detail biomarker profiles in CSF extracted using either gravity drip or aspiration.
Methods
Biomarkers for β-amyloidopathy (Aβ1–42, Aβ1–40), tauopathy (total tau), or synapse pathology (BACE1, Neurogranin Trunc-p75, α-synuclein) were assessed between gravity or aspiration extraction methods in a sub-population of the Australian Imaging, Biomarkers and Lifestyle (AIBL) study (cognitively normal, N = 36; mild cognitive impairment, N = 8; Alzheimer’s disease, N = 6).
Results
High biomarker concordance between extraction methods was seen (concordance correlation > 0.85). Passing Bablock regression defined low beta coefficients indicating high scalability.
Conclusions
Levels of these commonly assessed CSF biomarkers are not influenced by extraction method. Results of this study should be incorporated into new consensus guidelines for CSF collection, storage, and analysis of biomarkers
Analysis of wear-related failures in long-term follow-up of crosslinked polyethylene hip sockets
The publication of our long-term hip replacement follow-up study computer analysis has clearly demonstrated the
association between polyethylene (polyethylene/UHMWPE) wear on the one hand and pain, interface widening
and osteolysis on the other1. From a total of 97 cases, seven had true failure and needed ultimate revision. These
seven cases formed the nucleus of the current study (Group 1). The course of events could then be analysed in
great detail, and compared with the other 90 cases (Groups 2, 3, and 4).
The purpose of this paper was to confirm the role of polyethylene wear (the independent variable) in the limitation
of longevity of the implant; furthermore to identify the cut-off point of wear that is considered acceptable.
At the same time quantification of P, I, O (pain, interface widening and osteolysis) was studied (the dependent
variables). Once again, computer analysis provided us with detailed values that would constitute the cut-off points
for acceptance.
These findings then enabled us to categorise the 97 cases into four groups. Of special interest was Group 2:
‘impending failure’. Even though none of the nine cases in Group 2 were revised, this study clearly demonstrated
that they should be classified as failures and managed accordingly.
In this study some other controversial issues were addressed: the degree of wear proved important as opposed
to the tempo, which was not! Equally unimpressive were the patients’ age, activity and body mass, which according
to digital analysis had little effect on implant longevity.http://www.charpublications.co.za/C_JournalsORTH.as
Long-term evaluation of polyethylene wear in total hip replacement : a statistical analysis of the association between the degree of wear versus pain, interface change, osteopysis and implant failure
With over 3.5 decades dedicated exclusively to total joint replacement, our arthroplasty unit has repeatedly identified
and reported a clear correlation between cup wear on the one hand, and pain, interface widening and osteolytic
failure on the other1. However, in view of the fact that this statement has sparked some controversy, clarification
of this correlation became imperative, particularly in view of important clinical consequences.
Materials and methods were provided by a potentially long-lasting gamma crosslinked cup. The arthroplasty follow-
up ranged from 10-33 years. Objective clinical, radiographic and pathological evaluations were backed by
computer analysis through the Department of Statistics at the University of Pretoria.
We are able to conclude that the statistical correlation between wear, on the one hand, versus pain, interface
effects and osteolysis on the other, was no coincidence but instead proved to be clearly conclusive. Of great
importance is the fact that this study allowed us to set new objective criteria for true failure as well as impending
failure, thus guiding us towards sensible decision-making in terms of revision surgery in these complex
issues. Cup wear was thus clearly identified as the overwhelming leading variable in long-term prognosis in this
type of total hip replacement.http://www.charpublications.co.za/C_JournalsORTH.as
Análisis general de sistemas productivos claves y sus indicadores a nivel nacional en el contexto de crecimiento verde
El concepto de crecimiento verde fue incluido en el Plan Nacional de Desarrollo 2014-2018 “Todos por un Nuevo País” con el objetivo de buscar el desarrollo económico sostenible, la competitividad y la reducción de vulnerabilidades al cambio climático. En este informe se busca dar a conocer el estado actual de los indicadores de crecimiento verde para diferentes sistemas productivos agropecuarios en Colombia e identificar las opciones tecnológicas que permitan mejorar dichos indicadores con el fin de incrementar la productividad de la tierra sin afectar los demás indicadores de crecimiento verde.
Para lograr esto se han propuesto en este estudio cinco fases que van desde la fase de preparación, un análisis general a nivel nacional, un análisis detallado a nivel regional, un análisis de barreras para la implementación de medidas y recomendaciones. Este reporte corresponde a la fase dos del estudio sobre análisis general.
La línea base de expansión en área proyectada para los cinco sistemas productivos, la construcción y estimación de los indicadores a nivel nacional para cada uno de los sistemas productivos y una lista de opciones tecnológicas que pueden contribuir al crecimiento verde en estos sistemas productivos. Posteriormente se estimará el potencial que tiene cada tecnología sobre los indicadores de crecimiento verde. En este estudio también se incluye la metodología y resultados sobre el proceso de priorización de los sistemas productivos.
The concept of green growth was included in the National Development Plan 2014-2018 "All for a New Country" with the objective of seeking sustainable economic development, competitiveness and the reduction of vulnerabilities in climate change. This report seeks to publicize the current status of green growth indicators for different agricultural production systems in Colombia and identify the technological options that allow improving the indicators in order to increase the productivity of the land without affecting the other indicators of green growth
To achieve this, five phases have been improved in this study, ranging from the preparation phase, a general analysis at the national level, detailed analysis at the regional level, an analysis of barriers to the implementation of measures and recommendations. This report corresponds to the phase of the study on general analysis.
The baseline projected in this area for the five productive systems, the construction and the estimation of the indicators at national level for each one of the productive systems and a list of technological options that can contribute to the green growth in these productive systems. Subsequently, the potential of each technology on green growth indicators will be estimated. This study also includes the methodology and results on the process of prioritization of productive systems.The concept of green growth was included in the National Development Plan 2014-2018 "All for a New Country" with the objective of seeking sustainable economic development, competitiveness and the reduction of vulnerabilities in climate change. This report seeks to publicize the current status of green growth indicators for different agricultural production systems in Colombia and identify the technological options that allow improving the indicators in order to increase the productivity of the land without affecting the other indicators of green growth
To achieve this, five phases have been improved in this study, ranging from the preparation phase, a general analysis at the national level, detailed analysis at the regional level, an analysis of barriers to the implementation of measures and recommendations. This report corresponds to the phase of the study on general analysis.
The baseline projected in this area for the five productive systems, the construction and the estimation of the indicators at national level for each one of the productive systems and a list of technological options that can contribute to the green growth in these productive systems. Subsequently, the potential of each technology on green growth indicators will be estimated. This study also includes the methodology and results on the process of prioritization of productive systems
Burden and risk factors for Pseudomonas aeruginosa community-acquired pneumonia:a Multinational Point Prevalence Study of Hospitalised Patients
Pseudornonas aeruginosa is a challenging bacterium to treat due to its intrinsic resistance to the antibiotics used most frequently in patients with community-acquired pneumonia (CAP). Data about the global burden and risk factors associated with P. aeruginosa-CAP are limited. We assessed the multinational burden and specific risk factors associated with P. aeruginosa-CAP.
We enrolled 3193 patients in 54 countries with confirmed diagnosis of CAP who underwent microbiological testing at admission. Prevalence was calculated according to the identification of P. aeruginosa. Logistic regression analysis was used to identify risk factors for antibiotic-susceptible and antibiotic-resistant P. aeruginosa-CAP.
The prevalence of P. aeruginosa and antibiotic-resistant P. aeruginosa-CAP was 4.2% and 2.0%, respectively. The rate of P. aeruginosa CAP in patients with prior infection/colonisation due to P. aeruginosa and at least one of the three independently associated chronic lung diseases (i.e. tracheostomy, bronchiectasis and/or very severe chronic obstructive pulmonary disease) was 67%. In contrast, the rate of P. aeruginosa-CAP was 2% in patients without prior P. aeruginosa infection/colonisation and none of the selected chronic lung diseases. The multinational prevalence of P. aeruginosa-CAP is low.
The risk factors identified in this study may guide healthcare professionals in deciding empirical antibiotic coverage for CAP patients
Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk
BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat
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