8 research outputs found
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Stability of flows of thermo-viscoelastic fluids between rotating coaxial circular cylinders
We investigate in this thesis, the problem of stability
of thermo-viscoelastic fluid flow between rotating
coaxial cylinders. By using the thermo-viscoelastic
constitutive equations given by Eringen, we reduce the
equations of motion into a form suitable for stability
analysis. The course of reduction which we follow yields
some interesting intermediate results. The solution for
the steady state couette flow problem is found. Interestingly
enough, the velocity field for this problem is found
to be identical with the classical viscous case and the
case of a Reiner-Rivlin fluid, but the temperature and
pressure fields are different. The non-dimensional forms
of the equations of motion governing the couette flow of
thermo-viscoelastic fluids in a heat reservoir are given.
These equations are reduced further by considering a small
gap between the cylinders and by imposing some physically
reasonable mechanical and geometrical restrictions on the
flow. This results in a secular equation which forms a
characteristic value problem. The solution of the characteristic
value problem has been obtained and this yields a
criterion for stability in terms of a critical Taylor number.
In general, the critical values of Taylor numbers are found
to be higher than corresponding ones in classical hydrodynamic
stability problems, which implies that thermo-viscoelastic
fluids are more stable, in a couette flow, than
classical viscous fluids under a similar situation. Comparing
this result with existing investigations in non-
Newtonian fluids we find that, like Bingham fluids, thermoviscoelastic
fluids are more stable than viscous and
Reiner-Rivlin fluids
Massive spinal-ischial dysplasia and extensive spinal dyssygmentation in a Tunisian child with severe form of Cleido- cranial dysplasia
Abstract Kyphoscoliosis is a complication of some bone dysplasias, including Cleido-cranial dysplasia (CCD). We report on massive spinal dysplasia secondary to severe spinal dyssygmentation associated with marked defective ossification of the ischium, detected in a Tunisian female child with a severe form of Cleido-cranial dysplasia. Literature review on Cleido cranial dysplasia and associated spinal abnormalities showed no previous similar reports as encountered in our patient
Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey
Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
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Stability of convective flows in porous media
The stability of fluids in porous media subject to
various physical and geometrical conditions is studied
here. Criteria for the onset of convective motions are
given in terms of critical temperature gradients or heat
sources. The general method used involves the linearization
of the field equations about the hydrostatic solutions
and the reduction of the linear equations to an
appropriate linear eigenvalue problem for certain Positive
operators. Variational methods are then used to
approximate the minimum eigenvalues which yield the
stability criteria
Combining Gene Mutation with Expression of Candidate Genes to Improve Diagnosis of Escobar Syndrome
Escobar syndrome is a rare, autosomal recessive disorder that affects the musculoskeletal system and the skin. Mutations in the CHRNG and TPM2 genes are associated with this pathology. In this study, we conducted a clinical and genetic investigation of five patients and also explored via in silico and gene expression analysis their phenotypic variability. In detail, we identified a patient with a novel composite heterozygous variant of the CHRNG gene and two recurrent mutations in both CHRNG and TPM2 in the rest of the patients. As for the clinical particularities, we reported a list of modifier genes in a patient suffering from myopathy. Moreover, we identified decreased expression of IGF-1, which could be related to the short stature of Escobar patients, and increased expression of POLG1 specific to patients with TPM2 mutation. Through this study, we identified the genetic spectrum of Escobar syndrome in the Tunisian population, which will allow setting up genetic counseling and prenatal diagnosis for families at risk. In addition, we highlighted relevant biomarkers that could differentiate between patients with different genetic defects
Subtotal amelia in a child with autosomal recessive hypohidrotic ectodermal dysplasia
We report an inbred Tunisian family, in which the proband manifested signs of hypohidrotic ectodermal dysplasia, subtotal amelia, scoliosis and left renal agenesis. Two other family members had the full clinical criteria of hypohidrotic ectodermal dysplasia, characterized by deficient sweat glands, hypodontia, hypoplasia of the mucous glands, and fine hair. Nine family subjects had variable clinical expression of the disorder
Torticollis in Connection with Spine Phenotype
Purpose: Torticollis is not of uncommon occurrence in orthopaedic departments. Various theories and studies concerning the pathogenesis of the deformity have been suggested. We aimed to highlight and discuss the underlying cervical and spine malformation complex in correlation with torticollis via radiographic and tomographic analysis and its connection with a specific syndromic entity. Methods: Torticollis has been recognised in six patients (2 boys and 4 girls with an age range of 14–18 years), in addition to a couple of parents manifested persistent backpain. A variable spine malformation complex was the main reason behind torticollis. In addition, some patients manifested plagiocephaly, facial asymmetry and scoliosis/kyphoscoliosis. In some patients, conventional radiographs were of limited value because of the overlapping anatomical structures. Three-dimensional reconstruction CT scanning was the modality of choice, which enlightens the path for the phenotypic characterisation. Results: A 16-year-old-boy presented with torticollis in correlation with pathologic aberration of the spine cartilaginous stage was analysed via 3DCT scan. Comprehensive clinical and radiological phenotypes were in favour of spondylomegepiphyseal dysplasia. The genotype showed a mutation of the NKX3-2 (BAPX1) gene compatible with the diagnosis of spondylo-meg-epiphyseal-metaphyseal dysplasia. His younger male sibling and parents were heterozygous carriers. In two patients with pseudoachondroplasia syndrome, in which odontoid hypoplasia associated with cervical spine synchondrosis causing life-threatening torticollis, Cartilage oligomeric matrix protein (COMP) gene mutation was identified. MURCS syndrome has been diagnosed in two unrelated girls. Torticollis associated with cervical kyphosis was the major presentation since early childhood. Interestingly, one girl showed omovertebral bones of the lower cervical and upper thoracic spine. Her karyotype manifested a balanced translocation of 46 XX, t (14q; 15q). Conclusion: To detect the underlying etiological diagnosis of torticollis, a skeletal survey was the primary diagnostic tool. Conventional radiographs of the craniocervical junction and spine resulted in confusing readings because of the overlapping anatomical structures. Cranio-cervical malformation complex could have serious neurological deficits, especially for children with indefinite diagnosis of torticollis. The widely used term of congenital muscular torticollis resulted in morbid or mortal consequences. Moreover, some patients received vigorous physical therapy on the bases of muscular torticollis. Sadly speaking, this resulted in grave complications. Understanding the imaging phenotype and the genotype in such patients is the baseline tool for precise and proper management. The value of this paper is to sensitise physicians and orthopaedic surgeons to the necessity of comprehensive clinical and radiological phenotypic characterisations in patients with long term skeletal pathology