2,031 research outputs found
A cybernetic perspective on methods and process models in collaborative designing
Cybernetic thinking provides a framework to understand the issues in creating and using methods and process models during collaborative designing. It can help understand what takes place while the creation and use is unfolding. This viewpoint allows methods and process models to be framed as aiding human decision-making, and as supporting the organisation of design activities. It casts light on how a team acts and what are they doing to solve design problems, by considering that they react to changes in the perceived solution state or goal state. Cybernetics thus provides an articulation of mechanisms for doing design. By identifying virtues that support creation and use of methods and process models during designing, cybernetics could thus help teams to design more effectively.
This article considers the creation and use of process models and methods in design from a cybernetic perspective. We suggest that a process model and method are similar in nature, in that they both give guidance for progressing the design according to the circumstances encountered. Cybernetic principles are interpreted to help understand the role of modelling and method use in design process evolution.International Design Conference - DESIGN 201
Evaluating surgical skills from kinematic data using convolutional neural networks
The need for automatic surgical skills assessment is increasing, especially
because manual feedback from senior surgeons observing junior surgeons is prone
to subjectivity and time consuming. Thus, automating surgical skills evaluation
is a very important step towards improving surgical practice. In this paper, we
designed a Convolutional Neural Network (CNN) to evaluate surgeon skills by
extracting patterns in the surgeon motions performed in robotic surgery. The
proposed method is validated on the JIGSAWS dataset and achieved very
competitive results with 100% accuracy on the suturing and needle passing
tasks. While we leveraged from the CNNs efficiency, we also managed to mitigate
its black-box effect using class activation map. This feature allows our method
to automatically highlight which parts of the surgical task influenced the
skill prediction and can be used to explain the classification and to provide
personalized feedback to the trainee.Comment: Accepted at MICCAI 201
Does self-monitoring reduce blood pressure? Meta-analysis with meta-regression of randomized controlled trials
Introduction. Self-monitoring of blood pressure (BP) is an increasingly common part of hypertension management. The objectives of this systematic review were to evaluate the systolic and diastolic BP reduction, and achievement of target BP, associated with self-monitoring.
Methods. MEDLINE, Embase, Cochrane database of systematic reviews, database of abstracts of clinical effectiveness, the health technology assessment database, the NHS economic evaluation database, and the TRIP database were searched for studies where the intervention included self-monitoring of BP and the outcome was change in office/ambulatory BP or proportion with controlled BP. Two reviewers independently extracted data. Meta-analysis using a random effects model was combined with meta-regression to investigate heterogeneity in effect sizes.
Results. A total of 25 eligible randomized controlled trials (RCTs) (27 comparisons) were identified. Office systolic BP (20 RCTs, 21 comparisons, 5,898 patients) and diastolic BP (23 RCTs, 25 comparisons, 6,038 patients) were significantly reduced in those who self-monitored compared to usual care (weighted mean difference (WMD) systolic −3.82 mmHg (95% confidence interval −5.61 to −2.03), diastolic −1.45 mmHg (−1.95 to −0.94)). Self-monitoring increased the chance of meeting office BP targets (12 RCTs, 13 comparisons, 2,260 patients, relative risk = 1.09 (1.02 to 1.16)). There was significant heterogeneity between studies for all three comparisons, which could be partially accounted for by the use of additional co-interventions.
Conclusion. Self-monitoring reduces blood pressure by a small but significant amount. Meta-regression could only account for part of the observed heterogeneity
Superconductivity at the Border of Electron Localization and Itinerancy
The superconducting state of iron pnictides and chalcogenides exists at the
border of antiferromagnetic order. Consequently, these materials could provide
clues about the relationship between magnetism and unconventional
superconductivity. One explanation, motivated by the so-called bad-metal
behaviour of these materials, proposes that magnetism and superconductivity
develop out of quasi-localized magnetic moments which are generated by strong
electron-electron correlations. Another suggests that these phenomena are the
result of weakly interacting electron states that lie on nested Fermi surfaces.
Here we address the issue by comparing the newly discovered alkaline iron
selenide superconductors, which exhibit no Fermi-surface nesting, to their iron
pnictide counterparts. We show that the strong-coupling approach leads to
similar pairing amplitudes in these materials, despite their different Fermi
surfaces. We also find that the pairing amplitudes are largest at the boundary
between electronic localization and itinerancy, suggesting that new
superconductors might be found in materials with similar characteristics.Comment: Version of the published manuscript prior to final journal-editting.
Main text (23 pages, 4 figures) + Supplementary Information (14 pages, 7
figures, 3 tables). Calculation on the single-layer FeSe is added.
Enhancement of the pairing amplitude in the vicinity of the Mott transition
is highlighted. Published version is at
http://www.nature.com/ncomms/2013/131115/ncomms3783/full/ncomms3783.htm
Normal-State Spin Dynamics and Temperature-Dependent Spin Resonance Energy in an Optimally Doped Iron Arsenide Superconductor
The proximity of superconductivity and antiferromagnetism in the phase
diagram of iron arsenides, the apparently weak electron-phonon coupling and the
"resonance peak" in the superconducting spin excitation spectrum have fostered
the hypothesis of magnetically mediated Cooper pairing. However, since most
theories of superconductivity are based on a pairing boson of sufficient
spectral weight in the normal state, detailed knowledge of the spin excitation
spectrum above the superconducting transition temperature Tc is required to
assess the viability of this hypothesis. Using inelastic neutron scattering we
have studied the spin excitations in optimally doped BaFe1.85Co0.15As2 (Tc = 25
K) over a wide range of temperatures and energies. We present the results in
absolute units and find that the normal state spectrum carries a weight
comparable to underdoped cuprates. In contrast to cuprates, however, the
spectrum agrees well with predictions of the theory of nearly antiferromagnetic
metals, without complications arising from a pseudogap or competing
incommensurate spin-modulated phases. We also show that the temperature
evolution of the resonance energy follows the superconducting energy gap, as
expected from conventional Fermi-liquid approaches. Our observations point to a
surprisingly simple theoretical description of the spin dynamics in the iron
arsenides and provide a solid foundation for models of magnetically mediated
superconductivity.Comment: 8 pages, 4 figures, and an animatio
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Analysis of polymorphisms in 16 genes in type 1 diabetes that have been associated with other immune-mediated diseases.
BACKGROUND: The identification of the HLA class II, insulin (INS), CTLA-4 and PTPN22 genes as determinants of type 1 diabetes (T1D) susceptibility indicates that fine tuning of the immune system is centrally involved in disease development. Some genes have been shown to affect several immune-mediated diseases. Therefore, we tested the hypothesis that alleles of susceptibility genes previously associated with other immune-mediated diseases might perturb immune homeostasis, and hence also associate with predisposition to T1D. METHODS: We resequenced and genotyped tag single nucleotide polymorphisms (SNPs) from two genes, CRP and FCER1B, and genotyped 27 disease-associated polymorphisms from thirteen gene regions, namely FCRL3, CFH, SLC9A3R1, PADI4, RUNX1, SPINK5, IL1RN, IL1RA, CARD15, IBD5-locus (including SLC22A4), LAG3, ADAM33 and NFKB1. These genes have been associated previously with susceptibility to a range of immune-mediated diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Graves' disease (GD), psoriasis, psoriatic arthritis (PA), atopy, asthma, Crohn disease and multiple sclerosis (MS). Our T1D collections are divided into three sample subsets, consisting of set 1 families (up to 754 families), set 2 families (up to 743 families), and a case-control collection (ranging from 1,500 to 4,400 cases and 1,500 to 4,600 controls). Each SNP was genotyped in one or more of these subsets. Our study typically had approximately 80% statistical power for a minor allele frequency (MAF) >5% and odds ratios (OR) of 1.5 with the type 1 error rate, alpha = 0.05. RESULTS: We found no evidence of association with T1D at most of the loci studied 0.02 <P < 1.0. Only a SNP in ADAM33, rs2787094, was any evidence of association obtained, P = 0.0004 in set 1 families (relative risk (RR) = 0.78), but further support was not observed in the 4,326 cases and 4,610 controls, P = 0.57 (OR = 1.02). CONCLUSION: Polymorphisms in a variety of genes previously associated with immune-mediated disease susceptibility and/or having effects on gene function and the immune system, are unlikely to be affecting T1D susceptibility in a major way, even though some of the genes tested encode proteins of immune pathways that are believed to be central to the development of T1D. We cannot, however, rule out effect sizes smaller than OR 1.5
Pediatric Differentiated Thyroid Carcinoma in The Netherlands: A Nationwide Follow-Up Study
Introduction: Treatment for differentiated thyroid carcinoma (DTC) in pediatric patients is based mainly on evidence from adult series due to lack of data from pediatric cohorts. Our objective was to evaluate presentation, treatment-related complications, and long-term outcome in patients with pediatric DTC in the Netherlands. Patients and methods: In this nationwide study, presentation, complications and outcome of patients with pediatric DTC (age at diagnosis ≤18 years) treated in the Netherlands between 1970 and 2013 were assessed using medical records. Results: We identified 170 patients. Overall survival was 99.4% after median follow-up of 13.5 (range 0.3–44.7) years. Extensive follow-up data were available for 105 patients (83.8% women), treated in 39 hospitals. Median age at diagnosis was 15.6 (range 5.8–18.9) years. At initial diagnosis, 43.8% of the patients had cervical lymph node metastases; 13.3% had distant metastases. All patients underwent total thyroidectomy. Radioiodine was administered to 97.1%, with a median cumulative activity of 5.66 (range 0.74–35.15) GBq. Lifelong postoperative complications (permanent hypoparathyroidism and/or recurrent laryngeal nerve injury) were present in 32.4% of the patients. At last known follow-up, 8.6% of the patients had persistent disease and 7.6% experienced a recurrence. TSH suppression was not associated with recurrences (OR 2.00, 95% CI 0.78 to 5.17, P = 0.152). Conclusions: Survival of pediatric DTC is excellent. Therefore, minimizing treatment-related morbidity takes major priority. Our study shows a frequent occurrence of lifelong postoperative complications. Adverse effects may be reduced by centralization of care, which is crucial for children with DTC
Upregulation of the cell-cycle regulator RGC-32 in Epstein-Barr virus-immortalized cells
Epstein-Barr virus (EBV) is implicated in the pathogenesis of multiple human tumours of lymphoid and epithelial origin. The virus infects and immortalizes B cells establishing a persistent latent infection characterized by varying patterns of EBV latent gene expression (latency 0, I, II and III). The CDK1 activator, Response Gene to Complement-32 (RGC-32, C13ORF15), is overexpressed in colon, breast and ovarian cancer tissues and we have detected selective high-level RGC-32 protein expression in EBV-immortalized latency III cells. Significantly, we show that overexpression of RGC-32 in B cells is sufficient to disrupt G2 cell-cycle arrest consistent with activation of CDK1, implicating RGC-32 in the EBV transformation process. Surprisingly, RGC-32 mRNA is expressed at high levels in latency I Burkitt's lymphoma (BL) cells and in some EBV-negative BL cell-lines, although RGC-32 protein expression is not detectable. We show that RGC-32 mRNA expression is elevated in latency I cells due to transcriptional activation by high levels of the differentially expressed RUNX1c transcription factor. We found that proteosomal degradation or blocked cytoplasmic export of the RGC-32 message were not responsible for the lack of RGC-32 protein expression in latency I cells. Significantly, analysis of the ribosomal association of the RGC-32 mRNA in latency I and latency III cells revealed that RGC-32 transcripts were associated with multiple ribosomes in both cell-types implicating post-initiation translational repression mechanisms in the block to RGC-32 protein production in latency I cells. In summary, our results are the first to demonstrate RGC-32 protein upregulation in cells transformed by a human tumour virus and to identify post-initiation translational mechanisms as an expression control point for this key cell-cycle regulator
Evaluation of Quantitative EEG by Classification and Regression Trees to Characterize Responders to Antidepressant and Placebo Treatment
The study objective was to evaluate the usefulness of Classification and Regression Trees (CART), to classify clinical responders to antidepressant and placebo treatment, utilizing symptom severity and quantitative EEG (QEEG) data. Patients included 51 adults with unipolar depression who completed treatment trials using either fluoxetine, venlafaxine or placebo. Hamilton Depression Rating Scale (HAM-D) and single electrodes data were recorded at baseline, 2, 7, 14, 28 and 56 days. Patients were classified as medication and placebo responders or non-responders. CART analysis of HAM-D scores showed that patients with HAM-D scores lower than 13 by day 7 were more likely to be treatment responders to fluoxetine or venlafaxine compared to non-responders (p=0.001). Youden’s index γ revealed that CART models using QEEG measures were more accurate than HAM-D-based models. For patients given fluoxetine, patients with a decrease at day 2 in θ cordance at AF2 were classified by CART as treatment responders (p=0.02). For those receiving venlafaxine, CART identified a decrease in δ absolute power at day 7 at the PO2 region as characterizing treatment responders (p=0.01). Using all patients receiving medication, CART identified a decrease in δ absolute power at day 2 in the FP1 region as characteristic of nonresponse to medication (p=0.003). Optimal trees from the QEEG CART analysis primarily utilized cordance values, but also incorporated some δ absolute power values. The results of our study suggest that CART may be a useful method for identifying potential outcome predictors in the treatment of major depression
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