240 research outputs found
A Cost-Benefit Analysis for the Implementation of Lean Logistics to Aircraft Structural Repair at the Air Force Material Command\u27s Warner Robins Air Logistics Center/Depot
This research conducts a cost-benefit analysis of the implementation of lean logistics to the repair of aircraft structural components at the Air Force Material Command\u27s (AFMC) Warner Robins Air Logistics Center (WR-ALC). A literature review identifies new business practices in the automotive industry, collectively \u27termed lean production, that were translated by the RAND Corporation into a modified Air Force logistics system-- the lean logistics model.
Theoretical costs and benefits from the lean logistics model are translated into empirical costs and benefits associated with aircraft structural repair. The cost-benefit analysis results clearly demonstrate that express distribution costs for the sizable aircraft structural components significantly contribute to costs exceeding benefits for this specific depot logistics subsystem process
Drug resistance outcomes of long-term ART with tenofovir disoproxil fumarate in the absence of virological monitoring
Objectives: The resistance profiles of patients receiving long-term ART in sub-Saharan Africa have been poorly described. This study obtained a sensitive assessment of the resistance patterns associated with long-term tenofovir-based ART in a programmatic setting where virological monitoring is yet to become part of routine care.
Methods: We studied subjects who, after a median of 4.2 years of ART, replaced zidovudine or stavudine with tenofovir disoproxil fumarate while continuing lamivudine and an NNRTI. Using deep sequencing, resistance-associated mutations (RAMs) were detected in stored samples collected at tenofovir introduction (T0) and after a median of 4.0 years (T1).
Results: At T0, 19/87 (21.8%) subjects showed a detectable viral load and 8/87 (9.2%) had one or more major NNRTI RAMs, whereas 82/87 (94.3%) retained full tenofovir susceptibility. At T1, 79/87 (90.8%) subjects remained on NNRTI-based ART, 5/87 (5.7%) had introduced lopinavir/ritonavir due to immunological failure, and 3/87 (3.4%) had interrupted ART. Whilst 68/87 (78.2%) subjects maintained or achieved virological suppression between T0 and T1, a detectable viral load with NNRTI RAMs at T0 predicted lack of virological suppression at T1. Each treatment interruption, usually reflecting unavailability of the dispensary, doubled the risk of T1 viraemia. Tenofovir, lamivudine and efavirenz selected for K65R, K70E/T, L74I/V and Y115F, alongside M184V and multiple NNRTI RAMs; this resistance profile was accompanied by high viral loads and low CD4 cell counts.
Conclusions: Viraemia on tenofovir, lamivudine and efavirenz led to complex resistance patterns with implications for continued drug activity and risk of onward transmission
Chasing the ‘Killer’ Phonon Mode for the Rational Design of Low Disorder, High Mobility Molecular Semiconductors
Molecular vibrations play a critical role in the charge transport properties of weakly van der Waals bonded organic semiconductors. To understand which specific phonon modes contribute most strongly to the electron – phonon coupling and ensuing thermal energetic disorder in some of the most widely studied high mobility molecular semiconductors, we have combined state-of-the-art quantum mechanical simulations of the vibrational modes and the ensuing electron phonon coupling constants with experimental measurements of the low-frequency vibrations using inelastic neutron scattering and terahertz time-domain spectroscopy. In this way we have been able to identify the long-axis sliding motion as a ‘killer’ phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, we propose a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high mobility molecular semiconductors.Royal Society
German Research Foundation
European Research Council
Engineering and Physical Sciences Research Council
ARCHER UK National Supercomputing Service
Belgian National Fund for Scientific Research
Leverhulme Trust
Wiener-Anspach Foundation
Belgian Walloon Region
GENCI-CINES/IDRI
A novel soft tissue prediction methodology for orthognathic surgery based on probabilistic finite element modelling
Repositioning of the maxilla in orthognathic surgery is carried out for functional and aesthetic
purposes. Pre-surgical planning tools can predict 3D facial appearance by computing the
response of the soft tissue to the changes to the underlying skeleton. The clinical use of
commercial prediction software remains controversial, likely due to the deterministic nature
of these computational predictions. A novel probabilistic finite element model (FEM) for the
prediction of postoperative facial soft tissues is proposed in this paper. A probabilistic FEM
was developed and validated on a cohort of eight patients who underwent maxillary repositioning and had pre- and postoperative cone beam computed tomography (CBCT) scans
taken. Firstly, a variables correlation assessed various modelling parameters. Secondly, a
design of experiments (DOE) provided a range of potential outcomes based on uniformly
distributed input parameters, followed by an optimisation. Lastly, the second DOE iteration
provided optimised predictions with a probability range. A range of 3D predictions was
obtained using the probabilistic FEM and validated using reconstructed soft tissue surfaces
from the postoperative CBCT data. The predictions in the nose and upper lip areas accurately include the true postoperative position, whereas the prediction under-estimates the
position of the cheeks and lower lip. A probabilistic FEM has been developed and validated
for the prediction of the facial appearance following orthognathic surgery. This method
shows how inaccuracies in the modelling and uncertainties in executing surgical planning
influence the soft tissue prediction and it provides a range of predictions including a minimum and maximum, which may be helpful for patients in understanding the impact of surgery on the face
Low-dose TNF augments fracture healing in normal and osteoporotic bone by up-regulating the innate immune response
The mechanism by which trauma initiates healing remains unclear. Precise understanding of these events may define interventions for accelerating healing that could be translated to the clinical arena. We previously reported that addition of low-dose recombinant human TNF (rhTNF) at the fracture site augmented fracture repair in a murine tibial fracture model. Here, we show that local rhTNF treatment is only effective when administered within 24h of injury, when neutrophils are the major inflammatory cell infiltrate. Systemic administration of anti-TNF impaired fracture healing. Addition of rhTNF enhanced neutrophil recruitment and promoted recruitment of monocytes through CCL2 production. Conversely, depletion of neutrophils or inhibition of the chemokine receptor CCR2 resulted in significantly impaired fracture healing. Fragility, or osteoporotic, fractures represent a major medical problem as they are associated with permanent disability and premature death. Using a murine model of fragility fractures, we found that local rhTNF treatment improved fracture healing during the early phase of repair. If translated clinically, this promotion of fracture healing would reduce the morbidity and mortality associated with delayed patient mobilization
Status of Muon Collider Research and Development and Future Plans
The status of the research on muon colliders is discussed and plans are
outlined for future theoretical and experimental studies. Besides continued
work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy
collider, many studies are now concentrating on a machine near 0.1 TeV (CoM)
that could be a factory for the s-channel production of Higgs particles. We
discuss the research on the various components in such muon colliders, starting
from the proton accelerator needed to generate pions from a heavy-Z target and
proceeding through the phase rotation and decay ()
channel, muon cooling, acceleration, storage in a collider ring and the
collider detector. We also present theoretical and experimental R & D plans for
the next several years that should lead to a better understanding of the design
and feasibility issues for all of the components. This report is an update of
the progress on the R & D since the Feasibility Study of Muon Colliders
presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A.
Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics
(Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics,
Accelerators and Beam
ATLAS Run 2 searches for electroweak production of supersymmetric particles interpreted within the pMSSM
A summary of the constraints from searches performed by the ATLAS collaboration for the electroweak production of charginos and neutralinos is presented. Results from eight separate ATLAS searches are considered, each using 140 fb−1 of proton-proton data at a centre-of-mass energy of √ = 13 TeV collected at the Large Hadron Collider during its second data-taking run. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, where R-parity conservation is assumed and the lightest supersymmetric particle is assumed to be the lightest neutralino. Constraints from previous electroweak, flavour and dark matter related measurements are also considered. The results are presented in terms of constraints on supersymmetric particle masses and are compared with limits from simplified models. Also shown is the impact of ATLAS searches on parameters such as the dark matter relic density and the spin-dependent and spin-independent scattering cross-sections targeted by direct dark matter detection experiments. The Higgs boson and Z boson ‘funnel regions’, where a low-mass neutralino would not oversaturate the dark matter relic abundance, are almost completely excluded by the considered constraints. Example spectra for non-excluded supersymmetric models with light charginos and neutralinos are also presented
Molecular and phenotypic characterisation of paediatric glioma cell lines as models for preclinical drug development.
Although paediatric high grade gliomas resemble their adult counterparts in many ways, there appear to be distinct clinical and biological differences. One important factor hampering the development of new targeted therapies is the relative lack of cell lines derived from childhood glioma patients, as it is unclear whether the well-established adult lines commonly used are representative of the underlying molecular genetics of childhood tumours. We have carried out a detailed molecular and phenotypic characterisation of a series of paediatric high grade glioma cell lines in comparison to routinely used adult lines
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