50 research outputs found

    Optimisation of the surfboard fin shape using computational fluid dynamics and genetic algorithms

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    During the sport of wave surfing, the fins on a surfboard play a major role in the overall performance of the surfer. This article presents the optimisation of a surfboard fin shape, using coupled genetic algorithms with the FLUENT® solver, aiming at the maximisation of the lift per drag ratio. The design-variable vector includes six components namely the chord length, the depth and the sweep angle of the fin as well as the maximum camber, the maximum camber position and the thickness of the hydrofoil (the four-digit NACA parametrization). The Latin hypercube sampling technique is utilised to explore the design space, resulting in 42 different fin designs. Fin and control volume models are created (using CATIA® V5) and meshed (unstructured using ANSYS® Workbench). Steady-state computations were performed using the FLUENT SST k−ω (shear stress transport k−ω) turbulence model at the velocity of 10 m/s and 10° angle of attack. Using the obtained lift and drag values, a response surface based model was constructed with the aim to maximise the lift-to-drag ratio. The optimisation problem was solved using the genetic algorithm provided by the MATLAB® optimisation toolbox and the response surface based model was iteratively improved. The resultant optimal fin design is compared with the experimental data for the fin demonstrating an increase in lift-to-drag ratio by approximately 62% for the given angle of attack of 10°

    Hybrid bone SPECT/CT reveals spleen calcification in sickle cell mutation and beta-thalassemia

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    We present a case of a 65 years-old male with sickle cell mutation and beta-thalassemia (Hb S/β-Thal), who had whole-body bone scan evaluation for osteomyelitis. The examination revealed high radiopharmaceutical uptake in the left abdomen. Further evaluation with hybrid single photon emission computed tomography/computed tomography (SPECT/CT) showed calcification of approximately the entire spleen, in the context of sickle cell anemia. This report highlights the role of SPECT/CT in such cases

    Atrial Flutter With 1:1 Atrioventricular Conduction and Profound Nonischemic ST Segment Depression

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    A 60-year-old lady presented to the emergency room with breathlessness, palpitations, dizziness and hypotension. The ECG showed narrow QRS complex tachycardia at a rate of 300 beats/min and downsloping ST segment depression. Following intravenous administration of adenosine, atrial flutter was confirmed and due to hemodynamic instability a direct current shock was delivered which restored sinus rhythm. The causes of such rapid ventricular rates in atrial flutter are discussed a propos with this case report

    Detection of Herplex Simplex Virus-1 and -2 in Cardiac Myxomas

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    The etiology of sporadic cardiac myxomas remains elusive. The tendency for these lesions to recur following resection, their immunopathological characteristics, along with their histological and molecular profile, may implicate the presence of an infective agent in this type of tumor. In this study, we investigated the presence of herpes simplex virus (HSV) DNA in a cohort of cardiac myxomas in a tertiary referral centre. Twenty-nine formalin-fixed paraffin-embedded (FFPE) sporadic cardiac myxomas were obtained, 17 of which were shown to be informative. These were compared to 19 macroscopically and microscopically normal heart tissue specimens. The detection of HSV-1 and -2 genomic sequences was achieved with the use of a combined nested PCR-Restriction Fragment Length Polymorphism methodology. The presence of HSV-1 and/or -2 DNA was demonstrated in 6 of 17 (35%) informative sporadic cardiac myxomas, whereas no HSV DNA was detected in normal heart tissues (P < 0.01). The existence of HSV-1/2 DNA in sporadic cardiac myxomas, along with its absence from normal heart tissues, reinforces the possibility that HSV infection might be involved in the development of these lesions. Our findings raise the point of anti-HSV medication postsurgically with a potential benefit in reducing the rate of recurrences

    OYXOY: A Modern NLP Test Suite for Modern Greek

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    This paper serves as a foundational step towards the development of a linguistically motivated and technically relevant evaluation suite for Greek NLP. We initiate this endeavor by introducing four expert-verified evaluation tasks, specifically targeted at natural language inference, word sense disambiguation (through example comparison or sense selection) and metaphor detection. More than language-adapted replicas of existing tasks, we contribute two innovations which will resonate with the broader resource and evaluation community. Firstly, our inference dataset is the first of its kind, marking not just \textit{one}, but rather \textit{all} possible inference labels, accounting for possible shifts due to e.g. ambiguity or polysemy. Secondly, we demonstrate a cost-efficient method to obtain datasets for under-resourced languages. Using ChatGPT as a language-neutral parser, we transform the Dictionary of Standard Modern Greek into a structured format, from which we derive the other three tasks through simple projections. Alongside each task, we conduct experiments using currently available state of the art machinery. Our experimental baselines affirm the challenging nature of our tasks and highlight the need for expedited progress in order for the Greek NLP ecosystem to keep pace with contemporary mainstream research

    Detection of Herplex Simplex Virus-1 and -2 in Cardiac Myxomas

    Get PDF
    The etiology of sporadic cardiac myxomas remains elusive. The tendency for these lesions to recur following resection, their immunopathological characteristics, along with their histological and molecular profile, may implicate the presence of an infective agent in this type of tumor. In this study, we investigated the presence of herpes simplex virus (HSV) DNA in a cohort of cardiac myxomas in a tertiary referral centre. Twenty-nine formalin-fixed paraffin-embedded (FFPE) sporadic cardiac myxomas were obtained, 17 of which were shown to be informative. These were compared to 19 macroscopically and microscopically normal heart tissue specimens. The detection of HSV-1 and -2 genomic sequences was achieved with the use of a combined nested PCRRestriction Fragment Length Polymorphism methodology. The presence of HSV-1 and/or -2 DNA was demonstrated in 6 of 17 (35%) informative sporadic cardiac myxomas, whereas no HSV DNA was detected in normal heart tissues (P &lt; 0.01). The existence of HSV-1/2 DNA in sporadic cardiac myxomas, along with its absence from normal heart tissues, reinforces the possibility that HSV infection might be involved in the development of these lesions. Our findings raise the point of anti-HSV medication postsurgically with a potential benefit in reducing the rate of recurrences

    Postoperative spinal infection mimicking systemic vasculitis with titanium-spinal implants

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    <p>Abstract</p> <p>Background</p> <p>Secondary systemic vasculitis after posterior spinal fusion surgery is rare. It is usually related to over-reaction of immune-system, to genetic factors, toxicity, infection or metal allergies.</p> <p>Case Description</p> <p>A 14 year-old girl with a history of extended posterior spinal fusion due to idiopathic scoliosis presented to our department with diffuse erythema and nephritis (macroscopic hemuresis and proteinuria) 5 months post surgery. The surgical trauma had no signs of inflammation or infection. The blood markers ESR and CRP were increased. Skin tests were positive for nickel allergy, which is a content of titanium alloy. The patient received corticosteroids systematically (hydrocortisone 10 mg) for 6 months, leading to total recess of skin and systemic reaction. However, a palpable mass close to the surgical wound raised the suspicion of a late infection. The patient had a second surgery consisting of surgical debridement and one stage revision of posterior spinal instrumentation. Intraoperative cultures were positive to Staphylococcus aureus. Intravenous antibiotics were administered. The patient is now free of symptoms 24 months post revision surgery without any signs of recurrence of either vasculitis or infection.</p> <p>Literature Review</p> <p>Systemic vasculitis after spinal surgery is exceptionally rare. Causative factors are broad and sometimes controversial. In general, it is associated with allergy to metal ions. This is usually addressed with metal on metal total hip bearings. In spinal surgery, titanium implants are considered to be inert and only few reports have presented cases with systemic vasculitides. Therefore, other etiologies of immune over-reaction should always be considered, such as drug toxicity, infection, or genetic predisposition.</p> <p>Purposes and Clinical Relevance</p> <p>Our purpose was to highlight the difficulties during the diagnostic work-up for systemic vasculitis and management in cases of posterior spinal surgery.</p

    Bilateral adrenocortical carcinoma in a patient with multiple endocrine neoplasia type 1 (MEN1) and a novel mutation in the MEN1 gene

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    The incidence of adrenal involvement in MEN1 syndrome has been reported between 9 and 45%, while the incidence of adrenocortical carcinoma (ACC) in MEN1 patients has been reported between 2.6 and 6%. In the literature data only unilateral development of ACCs in MEN1 patients has been reported. We report a 31 years-old female MEN1-patient, in whom hyperplasia of the parathyroid glands, prolactinoma, non functioning pancreatic endocrine carcinoma and functioning bilateral adrenal carcinomas were diagnosed. Interestingly, a not previously described in the literature data, novel germline mutation (p.E45V) in exon 2 of MEN1 gene, was detected. The association of exon 2 mutation of the MEN1 gene with bilateral adrenal carcinomas in MEN1 syndrome, should be further investigated

    Modelling perineural tumour invasion

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    Perineural Tumour Invasion (PNI) describes a particularly aggressive mode of tumour spread where cells exhibit a propensity to infiltrate neural structures very rapidly. Clinical observations in the case of Non-Melanoma Skin Cancer (NMSC) suggest that cells of an epidermal tumour can invade the nerve endings lying in deeper tissue (up to 4mm) within, at most, six weeks. Various hypotheses exist regarding the mechanism behind PNI. One such hypothesis is that random motion alone may be sufficient to produce invasion within the observed time frame. Other hypotheses consider an up-regulated proliferation rate, a reduced apoptotic rate or the existence of a chemical gradient that attracts tumour cells towards the nerve sheath. We explore simple models of cellular processes such as migration, proliferation, death in the absence (and presence) of spatial gradients from a discrete stochastic cell-based perspective. We then associate a continuum description at the collective (tissue) level via deterministic models. These are obtained analytically as mean-field approximations of the stochastic setting in the thermodynamic limit. This enables comparison of the mean time of invasion produced by stochastic simulations of simple position- and velocity-jump processes to corresponding analytical estimates derived from the deterministic models. We, thus, formulate an appropriate mathematical framework which is used to predict the rates of the aforementioned cellular processes required for such rapid invasion. Our framework illustrates how analysis of the first moments of the distribution of first-passage times to an absorbing barrier by specific position- and velocity-jump processes enables a comparison between the different hypotheses. The setting is extended to include branching and annihilation processes. Finally, we use this ensemble of model mechanisms to compare both analytical and numerical predictions to biological observations so as to assess the validity of the different hypotheses. Testing each hypothesis using this framework shows that for realistic parameter values, derived from the biochemical literature, the existence of chemical or other spatial gradients is necessary to achieve sufficiently rapid invasion. All other hypotheses are rejected because they predict slower invasion by several orders of magnitude.</p
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