A FACED lift for cerebral blood flow imaging

ISSN:0027-8424ISSN:1091-649

On the influence of geometry updating on modal correlation of brake components.

In most industries dealing with vibration, test/analysis correlation of modal properties is considered a key aspect of the design process. The success of test/analysis methods however often show mixed results. The aim of this paper is to assess and answer some classical correlation problems in structural dynamics. First an investigation of correlation problems from tests is proposed. Tools based on the modal assurance criterion are presented to provide a deeper analysis of correlation and results improvement. In a second part, the need of FEM topology correlation and update is demonstrated, using an efficient morphing technique. Tolerances in the manufacturing process that are well accepted in design and production stages are shown to lead to significant degradation of the test/analysis correlation. An application to an industrial brake part is eventually presented, in an approach of correlation procedure automatization for recurrent use

Extracorporeal photopheresis for graft-versus-host disease: The role of patient, transplant, and classification criteria and hematologic values on outcome - Results from a large single-center study

BACKGROUND: Extracorporeal photopheresis (ECP) has been shown as active therapy for graft-versus-host disease (GVHD). STUDY DESIGN AND METHODS: The aim was to ascertain the role of ECP in 71 patients with steroid-refractory or -dependent acute and chronic GVHD (aGVHD and cGVHD) with special focus on hematologic variables and GVHD staging classification. A total of 34 patients were treated for aGVHD and 37 for cGVHD. RESULTS: The overall response rate (ORR) for aGVHD was 65% and the complete aGVHD-free survival was 50% (95% confidence interval [CI], 36%-70%). The ORR for cGVHD response was 81% while the complete cGVHD-free survival was 50% (95% CI, 34%-73%). The aGVHD-free survival was associated with aGVHD grading (Grade II 81%, Grade III 33%, and Grade IV 0%, p ≤ 0.00) and the absence of visceral involvement (77% vs. 33%, p = 0.03). The cGVHD-free survival was associated with the female sex (67% vs. 25%, p = 0.01) and with the limited form according to the Seattle classification (67% vs. 20%, p = 0.003). No role for hematologic values or apheresis cell count was found, except for the cGVHD ORR (p = 0.037). Transplant-related mortality and overall survival were associated with ECP response 0% versus 54% (p = 0.0001) and 77% versus 45% (p = 0.03) for aGVHD patients and 7% versus 14% (p = 0.02) and 73% versus 20% (p = 0.0003) for cGVHD patients, respectively. CONCLUSIONS: While confirming a higher probability of GVHD responses for early GVHD, our study shows no role of hematologic values or apheresis cell count on GVHD response

Ground States in the Diffusion-Dominated Regime

We consider macroscopic descriptions of particles where repulsion is modelled by non-linear power-law diffusion and attraction by a homogeneous singular kernel leading to variants of the Keller-Segel model of chemotaxis. We analyse the regime in which diffusive forces are stronger than attraction between particles, known as the diffusion-dominated regime, and show that all stationary states of the system are radially symmetric decreasing and compactly supported. The model can be formulated as a gradient flow of a free energy functional for which the overall convexity properties are not known. We show that global minimisers of the free energy always exist. Further, they are radially symmetric, compactly supported, uniformly bounded and $C^\infty$ inside their support. Global minimisers enjoy certain regularity properties if the diffusion is not too slow, and in this case, provide stationary states of the system. In one dimension, stationary states are characterised as optimisers of a functional inequality which establishes equivalence between global minimisers and stationary states, and allows to deduce uniqueness

Management of newly diagnosed patients with type 2 diabetes: What are the attitudes of physicians? A SUBITO!AMD survey on the early diabetes treatment in Italy

Early intensive therapy in type 2 diabetes can prevent complications. Nevertheless, metabolic control is often sub-optimal in newly diagnosed patients. This webbased survey aimed to evaluate opinions of physicians about treatment, priorities, and barriers in the care of patients first referred to diabetes clinics. Data on physician attitudes toward therapeutic preferences for two clinical case models (same clinical profile, except HbA1c levels of 8.6 and 7.3% at the first access, respectively) were collected. Participants were asked to rank from 1 (most important) to 6 (least important) a list of priorities and barriers associated with the care of new patients. Overall, 593 physicians participated. In both case models, metformin and education were primary options, although their combination with other classes of drugs varied substantially. Main priorities were ‘‘to teach the patient how to cope with the disease’’ and ‘‘to achieve HbA1c target’’; main barriers were ‘‘lack of time’’ and ‘‘long waiting list’’. At multivariate analyses, physicians from the South of Italy had a twofold higher likelihood to attribute a rank 1–2 to organizational barriers than those operating in the North (South vs. North: OR: 2.4; 95% CI 1.4–4.1; Center vs. North: OR: 2.4; 95% CI 0.9–3.2). In the absence of a widely accepted evidence-based therapeutic algorithm driving the therapeutic choices according to the patient characteristics, prescriptions vary according to physician preferences. Education is perceived as a key-strategy, but organizational barriers and geographic disparities are an obstacle. These findings can drive new strategies to reduce clinical inertia, attitudes variability, and geographic disparities

On the influence of geometry updating on modal correlation of brake components.

In most industries dealing with vibration, test/analysis correlation of modal properties is considered a key aspect of the design process. The success of test/analysis methods however often show mixed results. The aim of this paper is to assess and answer some classical correlation problems in structural dynamics. First an investigation of correlation problems from tests is proposed. Tools based on the modal assurance criterion are presented to provide a deeper analysis of correlation and results improvement. In a second part, the need of FEM topology correlation and update is demonstrated, using an efficient morphing technique. Tolerances in the manufacturing process that are well accepted in design and production stages are shown to lead to significant degradation of the test/analysis correlation. An application to an industrial brake part is eventually presented, in an approach of correlation procedure automatization for recurrent use

Evolution of the Microstructure and Performance of Pd/Ag - Based Thick Conductors

Pd/Ag-based inks are probably the most commonly used conductors in thick-film hybrid technology. The evolution of the microstructure of these films was studied on samples fired with isochronal cycles at a peak temperature in the range from 300℃ up to 850℃. The samples were investigated by means of X-ray diffraction, SEM and EDAX analysis techniques; the results of these analyses as well as those of thermogravimetry (TG, DTG) and differential thermal analysis (DTA), enable one to obtain a clear picture of the complex evolution of the microstructure of these conductors, which correlates quite strictly with the performance of the films in terms of resistivity and adhesion

The role of leptomeningeal collaterals in redistributing blood flow during stroke

Leptomeningeal collaterals (LMCs) connect the main cerebral arteries and provide alternative pathways for blood flow during ischaemic stroke. This is beneficial for reducing infarct size and reperfusion success after treatment. However, a better understanding of how LMCs affect blood flow distribution is indispensable to improve therapeutic strategies. Here, we present a novel in silico approach that incorporates case-specific in vivo data into a computational model to simulate blood flow in large semi-realistic microvascular networks from two different mouse strains, characterised by having many and almost no LMCs between middle and anterior cerebral artery (MCA, ACA) territories. This framework is unique because our simulations are directly aligned with in vivo data. Moreover, it allows us to analyse perfusion characteristics quantitatively across all vessel types and for networks with no, few and many LMCs. We show that the occlusion of the MCA directly caused a redistribution of blood that was characterised by increased flow in LMCs. Interestingly, the improved perfusion of MCA-sided microvessels after dilating LMCs came at the cost of a reduced blood supply in other brain areas. This effect was enhanced in regions close to the watershed line and when the number of LMCs was increased. Additional dilations of surface and penetrating arteries after stroke improved perfusion across the entire vasculature and partially recovered flow in the obstructed region, especially in networks with many LMCs, which further underlines the role of LMCs during stroke

The role of leptomeningeal collaterals in redistributing blood flow during stroke.

Leptomeningeal collaterals (LMCs) connect the main cerebral arteries and provide alternative pathways for blood flow during ischaemic stroke. This is beneficial for reducing infarct size and reperfusion success after treatment. However, a better understanding of how LMCs affect blood flow distribution is indispensable to improve therapeutic strategies. Here, we present a novel in silico approach that incorporates case-specific in vivo data into a computational model to simulate blood flow in large semi-realistic microvascular networks from two different mouse strains, characterised by having many and almost no LMCs between middle and anterior cerebral artery (MCA, ACA) territories. This framework is unique because our simulations are directly aligned with in vivo data. Moreover, it allows us to analyse perfusion characteristics quantitatively across all vessel types and for networks with no, few and many LMCs. We show that the occlusion of the MCA directly caused a redistribution of blood that was characterised by increased flow in LMCs. Interestingly, the improved perfusion of MCA-sided microvessels after dilating LMCs came at the cost of a reduced blood supply in other brain areas. This effect was enhanced in regions close to the watershed line and when the number of LMCs was increased. Additional dilations of surface and penetrating arteries after stroke improved perfusion across the entire vasculature and partially recovered flow in the obstructed region, especially in networks with many LMCs, which further underlines the role of LMCs during stroke