44 research outputs found
Redenvoeringen van wylen Petrus Camper, over de wyze, om de onderscheidene hartstogten op onze wezens te verbeelden : over de verbaazende overeenkomst tusschen de viervoetige dieren, de vogelen, de visschen en den mensch, en over het gedaante schoon : gehouden in de Teken Academie te Amsterdam /
No full textErrata, p. 1-3 at end.Frontispiece is engraved port. of the author, signed by Reinier Vinkeles and dated 1778. Plates I-XI are outline drawings, etched with engraving; I-II are têtes d'expression, III-VI are side views of animals, VII juxtaposes a woman and a mare, VIII-IX depict chiefly decorative motifs, X-XI depict birds.Mode of access: Internet.Inserted in Library's copy is five-line note in Dutch written in brown ink.Binding: printed stiff blue-gray wrappers, publisher's announcements on lower cover
Topology Optimization using CutFEM
No full textThe demand for better performing structural designs gives rise to the interest in topology optimization. An accurate geometry description is fundamental in the optimization process. The Cut Finite Element Method (CutFEM) can describe the object surface on a fixed grid with an immersed boundary. To this level set method, multiple techniques from the density method can be added. In this thesis project, the performance of 3D topology optimization using CutFEM is tested. A topology optimization model using CutFEM was developed. For the elements on the boundary (Cut Elements), a cut is made to split the element in a solid and fluid part. The Gauss points that represent each part are calculated in order to find the stiffness of the Cut Elements. The performance has been tested by performing finite element analysis with CutFEM. In order to perform topology optimization, the sensitivities are calculated with the adjoint method, a filter was used with Heaviside projection and mapping, and the Method of Moving Asymptotes (MMA) is used in order to find the design of the next iteration. In order to increase the length scale, an optional robust design method was implemented which creates an eroded and dilated design. The performance of topology optimization using CutFEM was tested by optimizing a structure for minimum compliance for a set of loading conditions. This was compared to topology optimization with classical Solid Isotropic Material with Penalization (SIMP) method. Firstly, it was found that Cut Elements are an accurate method to perform a finite element analysis. Next, it was found that topology optimization using CutFEM is able to obtain a better objective function than topology optimization using the SIMP method. The computational costs of the CutFEM method are substancially higher. In 3D topology optimization using CutFEM, the design changes can happen everywhere on the boundary, so that the initial structural design is of less importance than for 2D. Next, it was found that the robust design method works well in increasing the length scale, but the objective function is decreased and the initial design is more important. It is thought that CutFEM could best be used to perform optimization with the initial design computed by the SIMP method. Finally, the CutFEM method has been used in a Navier Stokes fluid solver with Brinkman penalization implementation. It was found that this does not work, and a fluid solver with a hard boundary method is required. It is recommended to implement the CutFEM method in a fluid solver with Nitsches method.European Wind Energy Masters (EWEM) | Rotor Design Trac
Metamorphosis naturalis, ofte Historische beschryvinghe van den oirspronk, aerd, eygenschappen ende vreemde veranderinghen der wormen, rupsen, maeden, vliegen, witjens, byen, motten ende dierghelijcke dierkens meer; niet uyt eenighe boecken, maer alleenelijck door eygen ervarentheyd uytgevonden, beschreven, en na da konst afgeteyckent.
No full textPagination, v. 1: [40], 152, [16] p., [63] leaves of plates. Vol. 2: [24], 288, [16] p., [43] leaves of plates. Vol. 3: [18], 54, [2], [55]-208 p., [21] leaves of plates (part folded).Signatures, v. 1: (a)⁸ (b)⁴ (c)⁸ A-I⁸ K⁴ [a]⁸. Vol. 2: [superscript pi]a⁸ [superscript pi]b⁴ a-s⁸ 2a-2b⁴. Vol. 3: a⁸ A-C⁸ D⁸(D3+1) E-N⁸.Each vol. has added t.p., the first 2 etched (2nd signed by Goedaerdt), the 3rd engraved. Vol. 2 has engraved port. of Goedaerdt by Reinier van Persyn after Willem Eversdyck. Added t.p.'s and port. as well as etched plates are hand colored.Vols. 1 & 2 issued in 1662 and 1667. Vol. 3 issued posthumously in 1669, edited by Johannes Mey. See Dict. of scientific biog., V, p. 440.Mode of access: Internet.John Landwehr's printed label on front pastedown of v. 1.Bound in 3 vols. in vellum. Lapped foredges. Author & title written at head of spine. Edges sprinkled blue.Includes index to first 2 vols
Interobserver Variability of the Diagnosis of Scaphoid Proximal Pole Fractures
No full text
Purpose Fractures of the proximal pole of the scaphoid are prone to adverse outcomes such as nonunion and avascular necrosis. Distinction of scaphoid proximal pole fractures from waist fractures is important for management but it is unclear if the distinction is reliable.
Methods A consecutive series of 29 scaphoid fractures from one tertiary hospital was collected consisting of 5 scaphoid proximal pole and 24 scaphoid waist fractures. Fifty-seven members of the Science of Variation Group (SOVG) were randomized to diagnose fracture location and displacement by using radiographs alone or radiographs and a computed tomography (CT) scan.
Results Observers reviewing radiographs alone and observers reviewing radiographs and CT scans both had substantial agreement on fracture location (κ = 0.82 and κ = 0.80, respectively; p = 0.54). Both groups had only fair agreement on fracture displacement (κ = 0.28 and κ = 0.35, respectively; p = 0.029).
Conclusion Proximal pole fractures are sufficiently distinct from proximal waist fractures that CT does not improve reliability of diagnosis.
Level of Evidence Level IV interobserver reliability case-control study.</jats:p
Surgical treatment of acute and chronic AC joint dislocations: Five-year experience with conventional and modified LARS fixation by a single surgeon
No full textSurgical treatment of acute and chronic AC joint dislocations: Five-year experience with conventional and modified LARS fixation by a single surgeon
No full textBackground: Different surgical fixation methods are available for the treatment of acromioclavicular (AC) joint dislocations. The aim of this study was to present the results of five years of experience with the Ligament Augmentation and Reconstruction System (LARS) fixation technique by a single surgeon. Methods: A single-center retrospective cohort study was performed. All patients treated for an AC joint dislocation with LARS fixation by the same surgeon between 2012 and 2016 (n = 20) were eligible for inclusion. All these dislocations were unstable injuries, Rockwood type-III or higher, requiring acute or chronic repair. The primary outcome was the QuickDASH score. Secondary outcomes were the Subjective Shoulder Value (SSV), Numerical Rating Scale (NRS) pain score, return to work, complications, and implant removal. Results: 17 patients (85%) were available for final follow-up. The median follow-up was 23 months (IQR; 17─34). The median QuickDASH score was 7 (IQR; 2-18), the median SSV was 90 (IQR; 80-90), and the median NRS pain score was 2 (IQR; 1-3). Patients returned to work after a median of 8 weeks (IQR; 6-12). There was no significant difference in functional outcome scores between acute and chronic repair, or between the conventional and modified LARS fixation groups. There were two major complications requiring revision surgery, one ruptured LARS ligament and one case of deep wound infection. Implant removal was performed in one patient. Conclusions: The LARS ligament fixation technique seems to be effective for the treatment of AC joint dislocations, resulting in good short- and mid-term patient-reported functional outcome. LARS fixation might also be an acceptable treatment option for active patients with symptomatic chronic AC dislocations. Level of evidence: Level III, Retrospective Comparative Study, Treatment Study
Proximal humerus fractures; conservative or surgical treatment?
No full textThere is an increasing incidence of proximal humerus fractures. Patients with proximal humerus fractures have traditionally been treated conservatively. During the past decades, however, various new osteosynthetic and prosthetic implants have been developed for the shoulder and surgical treatment of proximal humerus fractures has increased. However, recent literature in which conservative and surgical treatment of proximal humerus fractures is compared has shown no difference in functional outcome. The trend towards more frequent surgical treatment is thus not based on scientific evidence. In this article, we present the current state of affairs and attempt to give a nuanced picture of who will not, but also who might profit from surgical treatment of a proximal humerus fracture
Does Mindfulness Correlate With Physical Function and Pain Intensity in Patients With Upper Extremity Illness?
No full text Background: Mindfulness skills training interventions seem efficacious in increasing physical function and decreasing pain intensity in patients with chronic pain. The relationship of mindfulness and upper extremity complaints in patients presenting to orthopedic surgical practices is not known. The aim of this study was to assess if mindfulness has a relationship to physical function and pain intensity in patients with upper extremity illness. Methods: In this cross-sectional study, a total of 126 patients with a nontraumatic upper extremity condition were asked to fill out questionnaires assessing the 5 facets of mindfulness, pain intensity, and upper extremity physical function, along with clinical and demographic variables prior to their visit with the surgeon. Results: Nonreactivity to inner experiences was the only facet of mindfulness that was correlated with upper extremity physical function and pain intensity. The overall mindfulness score was correlated with pain intensity only. In multivariable analyses, mindfulness was not associated with either physical function or with pain intensity. Pain interference was the most important predictor of both pain intensity and physical function. Conclusions: Greater overall mindfulness was associated with lower pain intensity, and greater ability to be nonreactive to inner experiences was associated with both pain intensity and upper extremity physical function in bivariate but not multivariable analyses. Pain interference was the most important predictor of both pain intensity and upper extremity physical function. Psychosocial interventions focused on improving physical function and decreasing pain intensity in this population should focus primarily on reducing pain interference, and secondarily on teaching patients mindfulness skills. </jats:p
Management of displaced humeral surgical neck fractures in daily clinical practice: hanging does not re-align the fracture
No full textIntroduction: It is unclear if the collar and cuff treatment improve alignment in displaced surgical neck fractures of the proximal humerus. Therefore, this study evaluated if the neckshaft angle and extent of displacement would improve between trauma and onset of radiographically visible callus in non-operatively treated surgical neck fractures (Boileau type A, B, C). Materials and Methods: A consecutive series of patients (≥ 18 years old) were retrospectively evaluated from a level 1 trauma center in Australia (inclusion period: 2016–2020) and a level 2 trauma center in the Netherlands (inclusion period: 2004 to 2018). Patients were included if they sustained a Boileau-type fracture and underwent initial non-operative treatment. The first radiograph had to be obtained within 24 h after the initial injury and the follow-up radiograph(s) 1 week after trauma and before the start of radiographically visible callus. On each radiograph, the maximal medial gap (MMG), maximal lateral gap (MLG), and neck-shaft angle (NSA) were measured. Linear mixed modelling was performed to evaluate if these measurements would improve over time. Results: Sixty-seven patients were included: 25 type A, 11 type B, and 31 type C fractures. The mean age (range) was 68 years (24–93), and the mean number (range) of follow-up radiographs per patient was 1 (1–4). Linear mixed modelling on both MMG and MLG revealed no improvement during follow-up among the three groups. Mean NSA of type A fractures improved significantly from 161° at trauma to 152° at last follow-up (p-value = 0.004). Conclusions: Apart from humeral head angulation improvement in type A, there is no increase nor reduction in displacement among the three fracture patterns. Therefore, it is advised that surgical decision-making should be performed immediately after trauma. Level of clinical evidence: Level IV, retrospective case series.Biomechanical Engineerin
Are allogeneic blood transfusions associated with decreased survival after surgical treatment for spinal metastases?
No full textPerioperative allogeneic blood transfusions have been associated with decreased survival after surgical resection of primary and metastatic cancer. Studies investigating this association for patients undergoing resection of bone metastases are scarce and controversial.
We assessed (1) whether exposure to perioperative allogeneic blood transfusions was associated with decreased survival after surgery for spinal metastases and (2) if there was a dose-response relationship per unit of blood transfused. Additionally, we explored the risk factors associated with survival after surgery for spinal metastases.
This is a retrospective cohort study from two university medical centers.
There were 649 patients who had operative treatment for metastatic disease of the spine between 2002 and 2014. Patients with lymphoma or multiple myeloma were also included. We excluded patients with a revision procedure, kyphoplasty, vertebroplasty, and radiosurgery alone.
The outcome measure was survival after surgery. The date of death was obtained from the Social Security Death Index and medical charts.
Blood transfusions within 7 days before and 7 days after surgery were considered perioperative. A multivariate Cox proportional hazard model was used to assess the relationship between allogeneic blood transfusion as exposure versus non-exposure, and subsequently as continuous value; we accounted for clinical, laboratory, and treatment factors.
Four hundred fifty-three (70%) patients received perioperative blood transfusions, and the median number of units transfused was 3 (interquartile range: 2-6). Exposure to perioperative blood transfusion was not associated with decreased survival after accounting for all explanatory variables (hazard ratio [HR]: 1.03; 95% confidence interval [CI]: 0.80-1.31; p=.841). Neither did we find a dose-response relationship (HR: 1.01; 95% CI: 0.98-1.04; p=.420). Other factors associated with worse survival were older age, more severe comorbidity status, lower preoperativehemoglobin level, higher white blood cell count, higher calcium level, primary tumor type, previous systemic therapy, poor performance status, presence of lung, liver, or brain metastasis, and surgical approach.
Perioperative allogeneic blood transfusions were not associated with decreased survival after surgery for spinal metastases. More liberal transfusion policies might be warranted for patients undergoing surgery for spinal metastasis, although careful consideration is needed as other complications may occur
