90 research outputs found

    A consistent treatment of link and writhe for open rods, and their relation to end rotation

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    We combine and extend the work of Alexander & Antman \cite{alexander.82} and Fuller \cite{fuller.71,fuller.78} to give a framework within which precise definitions can be given of topological and geometrical quantities characterising the contortion of open rods undergoing large deformations under end loading. We use these definitions to examine the extension of known results for closed rods to open rods. In particular, we formulate the analogue of the celebrated formula Lk=Tw+WrLk=Tw+Wr (link equals twist plus writhe) for open rods and propose an end rotation, through which the applied end moment does work, in the form of an integral over the length of the rod. The results serve to promote the variational analysis of boundary-value problems for rods undergoing large deformations.Comment: 17 pages, 4 figure

    The Euler spiral of rat whiskers

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    This paper reports on an analytical study of the intrinsic shapes of 523 whiskers from 15 rats. We show that the variety of whiskers on a rat’s cheek, each of which has different lengths and shapes, can be described by a simple mathematical equation such that each whisker is represented as an interval on the Euler spiral. When all the representative curves of mystacial vibrissae for a single rat are assembled together, they span an interval extending from one coiled domain of the Euler spiral to the other. We additionally find that each whisker makes nearly the same angle of 47∘ with the normal to the spherical virtual surface formed by the tips of whiskers, which constitutes the rat’s tactile sensory shroud or “search space.” The implications of the linear curvature model for gaining insight into relationships between growth, form, and function are discussed

    Writhe formulas and antipodal points in plectonemic DNA configurations

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    The linking and writhing numbers are key quantities when characterizing the structure of a piece of supercoiled DNA. Defined as double integrals over the shape of the double-helix, these numbers are not always straightforward to compute, though a simplified formula exists. We examine the range of applicability of this widely-used simplified formula, and show that it cannot be employed for plectonemic DNA. We show that inapplicability is due to a hypothesis of Fuller theorem that is not met. The hypothesis seems to have been overlooked in many works.Comment: 20 pages, 7 figures, 47 reference

    TCT-251 Abnormal glucose metabolism and adverse event rates 12 months after treatment with contemporary drug-eluting stents:Insights from the BIO-RESORT Silent Diabetes study

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    BACKGROUND: Patients with abnormal glucose metabolism, including patients with undetected and thus untreated diabetes, may have higher event risks after percutaneous coronary intervention (PCI) with contemporary drug-eluting stents (DES). We assessed the prevalence and clinical impact of abnormal glucose metabolism in allcomer patients without previously known diabetes undergoing PCI. METHODS: The BIO-RESORT Silent Diabetes study, performed at Thoraxcentrum Twente, is a substudy of the randomized BIO-RESORT trial (NCT01674803). We performed an additional analysis identifying patients with an abnormal glucose metabolism by means of oral glucose tolerance testing (OGTT), and assessment of glycated hemoglobin A1c (HbA1c) with fasting plasma glucose (FPG) and clinical outcome at 12 months. RESULTS: Assessment of glucose metabolism revealed that of the 988 participants a total 330 (33.4%) patients had an abnormal metabolism, while 658 (66.6%) patients had a normal metabolism. Patients with abnormal glucose metabolism showed higher rates of the primary endpoint Target Vessel Failure (6.4% vs. 2.7%; p0.01), a composite of cardiac death, target vessel-related myocardial infarction, or target vessel revascularization. Multivariate analysis demonstrated that an abnormal glucose metabolism independently predicted adverse event risk (HR 2.2, 95%-CI:1.2-4.2). CONCLUSION: Abnormal glucose metabolism was detected in one out of three PCI all-comer patients and independently associated with a more than 2-fold higher event risk. Future intervention studies should determine whether meaningful benefits may accrue from routine glycaemia testing in such patients

    Manipulative therapy in addition to usual medical care accelerates recovery of shoulder complaints at higher costs: economic outcomes of a randomized trial

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    Background: Shoulder complaints are common in primary care and have unfavourable long term prognosis. Our objective was to evaluate the clinical effectiveness of manipulative therapy of the cervicothoracic spine and the adjacent ribs in addition to usual medical care (UMC) by the general practitioner in the treatment of shoulder complaints. Methods: This economic evaluation was conducted alongside a randomized trial in primary care. Included were 150 patients with shoulder complaints and a dysfunction of the cervicothoracic spine and adjacent ribs. Patients were treated with UMC (NSAID's, corticosteroid injection or referral to physical therapy) and were allocated at random (yes/no) to manipulative therapy (manipulation and mobilization). Patient perceived recovery, severity of main complaint, shoulder pain, disability and general health were outcome measures. Data about direct and indirect costs were collected by means of a cost diary. Results: Manipulative therapy as add-on to UMC accelerated recovery on all outcome measures included. At 26 weeks after randomization, both groups reported similar recovery rates (41% vs. 38%), but the difference between groups in improvement of severity of the main complaint, shoulder pain and disability sustained. Compared to the UMC group the total costs were higher in the manipulative group ((sic)1167 vs.(sic)555). This is explained mainly by the costs of the manipulative therapy itself and the higher costs due sick leave from work. The cost effectiveness ratio showed that additional manipulative treatment is more costly but also more effective than UMC alone. The cost-effectiveness acceptability curve shows that a 50%-probability of recovery with AMT within 6 months after initiation of treatment is achieved at (sic)2876. Conclusion: Manipulative therapy in addition to UMC accelerates recovery and is more effective than UMC alone on the long term, but is associated with higher costs

    Long-term outcome and chest pain in patients with true versus non-true bifurcation lesions treated with second-generation drug-eluting stents in the TWENTE trial

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    The objective of this study is to assess 3-year clinical outcome of patients with true bifurcation lesions (TBLs) versus non-true bifurcation lesions (non-TBLs) following treatment with second-generation drug-eluting stents (DES). TBLs are characterized by the obstruction of both main vessel and side-branch. Limited data are available on long-term clinical outcome following TBL treatment with newer-generation DES. We performed an explorative sub-study of the randomized TWENTE trial among 287 patients who had bifurcated target lesions with side-branches ≥2.0 mm. Patients were categorized into TBL (Medina classes: 1.1.1; 1.0.1; 0.1.1) versus non-TBL to compare long-term clinical outcome. A total of 116 (40.4 %) patients had TBL, while 171 (59.6 %) had non-TBL only. Target-lesion revascularization rates were similar (3.5 vs. 3.5 %; p = 1.0), and definite-or-probable stent thrombosis rates were low (both <1.0 %). The target-vessel myocardial infarction (MI) rate was 11.3 versus 5.3 % (p = 0.06), mostly driven by (periprocedural) MI ≤48 h from PCI. All-cause mortality and cardiac death rates were 8.7 versus 3.5 % (p = 0.06) and 3.5 versus 1.2 % (p = 0.22), respectively. The 3-year major adverse cardiac event rate for patients with TBL versus non-TBL was 20.0 versus 11.7 % (p = 0.05). At 1-, 2-, and 3-year follow-up, 6.5, 13.0, and 11.0 % of patients reported chest pain at less than or equal moderate physical effort, respectively, without any between-group difference. Patients treated with second-generation DES for TBL had somewhat higher adverse event rates than patients with non-TBL, but dissimilarities did not reach statistical significance. Up to 3-year follow-up, the vast majority of patients of both groups remained free from chest pain

    Describing whisker morphology of the Carnivora

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    One of the largest ecological transitions in carnivoran evolution was the shift from terrestrial to aquatic lifestyles, which has driven morphological diversity in skulls and other skeletal structures. In this paper, we investigate the association between those lifestyles and whisker morphology. However, comparing whisker morphology over a range of species is challenging since the number of whiskers and their positions on the mystacial pads vary between species. Also, each whisker will be at a different stage of growth and may have incurred damage due to wear and tear. Identifying a way to easily capture whisker morphology in a small number of whisker samples would be beneficial. Here, we describe individual and species variation in whisker morphology from two-dimensional scans in red fox, European otter and grey seal. A comparison of long, caudal whiskers shows inter-species differences most clearly. We go on to describe global whisker shape in 24 species of carnivorans, using linear approximations of curvature and taper, as well as traditional morphometric methods. We also qualitatively examine surface texture, or the presence of scales, using scanning electron micrographs. We show that gross whisker shape is highly conserved, with whisker curvature and taper obeying simple linear relationships with length. However, measures of whisker base radius, length, and maybe even curvature, can vary between species and substrate preferences. Specifically, the aquatic species in our sample have thicker, shorter whiskers that are smoother, with less scales present than those of terrestrial species. We suggest that these thicker whiskers may be stiffer and able to maintain their shape and position during underwater sensing, but being stiffer may also increase wear

    TCT-819 Prediabetes and its Impact on 1-Year Clinical Outcome After Treatment with Newer-Generation Drug-eluting Stents in 2,986 All-Comer Patients

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    BACKGROUND Prediabetes (Pre-DM) is a risk factor state for developing diabetes mellitus (DM). Yet it is unclear whether detection of Pre-DM by routine assessment of glycated haemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) among patients undergoing percutaneous coronary intervention (PCI) may help identify subjects with increased event risk. We assessed in all-comers who underwent PCI with contemporary drug-eluting stents (DES) the relation between glycaemia status and 1-year clinical outcome. METHODS HbA1c and FPG was determined in 2,362 non-DM participants in the multicenter, randomized, investigator-initiated TWENTE III trial, in order to identify Pre-DM (HbA1c 42-47mmol/mol; FPG 6.1- 6.9 mmol/L) and DM (HbA1c>=48mmol/mol; FPG >7 mmol/L). Another 624 patients had medically treated DM. The main clinical outcome parameter was a composite endpoint consisting of death, myocardial infarction, or revascularisation. RESULTS Glycaemic state was known in 2,986 trial participants: Pre- DM was present in 324 (11%), DM in 793 (27%), and normoglycaemia in 1,869 (63%) patients. Patients with Pre-DM and DM differed from normoglycemic patients in cardiovascular risk factors. The composite clinical endpoint in Pre-DM occurred in 11.1%, in DM in 10.5%, and in normoglycemic patients in 5.7% (

    Silencing markers are retained on pericentric heterochromatin during murine primordial germ cell development

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    Background: In the nuclei of most mammalian cells, pericentric heterochromatin is characterized by DNA methylation, histone modifications such as H3K9me3 and H4K20me3, and specific binding proteins l
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