Feasibility study of a constrained Dijkstra approach for optimal path planning of an unmanned surface vehicle in a dynamic maritime environment

Copy deposited in PEARL for open access under terms in penultimate paragraph of Optimal path planning is an important part of mission management hierarchy in a modern unmanned surface vehicle (USV) guidance, navigation and control frame work. USVs operate in a complex dynamic marine environment comprising of moving obstacles and sea surface currents. These characterising variables of configuration space change spatially as well as temporally. The current work investigates a well-known search technique, the Dijkstra algorithm, to resolve the problem of motion planning for a USV moving in a maritime environment. The current study extends the implementation of Dijkstra algorithm in a space cluttered with static and moving obstacles. In addition, downstream and upstream effects of sea surface currents of different intensities on optimal path planning are studied. The performance is verified in simulations with total path length and elapsed computational time considered as parameters to determine the effectiveness of the adopted approach. The results showed that the approach is effective for global path planning of USVs

A constrained A* approach towards optimal path planning for an unmanned surface vehicle in a maritime environment containing dynamic obstacles and ocean currents

Even after embargo period expires, authors' right to distribute as green open access is conditional on the green open access version including a DOI link, and on the green open access version being distributed under the Creative Commons CC-BY-NC-ND licence. In addition, the authors' right to distribute as green open access extends only to the author-generated post-print, not to any version with Elsevier typography.Efficient path planning is a critical issue for the navigation of modern unmanned surface vehicles (USVs) characterized by a complex operating environment having dynamic obstacles with a spatially variable ocean current. The current work explores an A* approach with an USV enclosed by a circular boundary as a safety distance constraint on generation of optimal waypoints to resolve the problem of motion planning for an USV moving in a maritime environment. Unlike existing work on USV navigation using graph based methods, this study extends the implementation of the proposed A* approach in an environment cluttered with static and moving obstacles and different current intensities. The study also examines the effect of headwind and tailwind currents moving in clockwise and anti clockwise direction respectively of different intensities on optimal waypoints in a partially dynamic environment. The performance of the proposed approach is verified in simulations for different environmental conditions. The effectiveness of the proposed approach is measured using two parameters, namely, path length and computational time as considered in other research works. The results show that the proposed approach is effective for global path planning of USVs

Traumatic quadriceps rupture in a patient with patellectomy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Acute traumatic, unilateral, quadriceps rupture after patellectomy is rare.</p> <p>Case presentation</p> <p>We present a 42-year old male who experienced a unilateral left quadriceps tendon rupture following assault by four people. Twenty-seven years before this injury, the patient had suffered ipsilateral femur and comminuted patellar fractures, which were managed by intramedullary nailing and patellectomy respectively. We performed primary end to end repair of the torn tendon. Postoperatively, histology revealed findings consistent with pre-existent degenerative changes. The patient made good recovery, and returned to his former occupation which was reliant on his ability to drive.</p> <p>Conclusion</p> <p>Degenerative changes of the tendon of the extensor mechanism of knee following patellectomy may predispose the quadriceps tendon to traumatic rupture. Early operative intervention and protracted rehabilitation are required to obtain the best functional results.</p

Reversal of end-stage renal disease after aortic dissection using renal artery stent: a case report

BACKGROUND: Medical management is the conventional treatment for Stanford Type B aortic dissections as surgery is associated with significant morbidity and mortality. The advent of endovascular interventional techniques has revived interest in treating end-organ complications of Type B aortic dissection. We describe a patient who benefited from endovascular repair of renal artery stenosis caused by a dissection flap, which resulted in reversal of his end-stage renal disease (ESRD). CASE PRESENTATION: A 69 y/o male with a Type B aortic dissection diagnosed two months earlier was found to have a serum creatinine of 15.2 mg/dL (1343.7 μmol/L) on routine visit to his primary care physician. An MRA demonstrated a rightward spiraling aortic dissection flap involving the origins of the celiac artery, superior mesenteric artery, and both renal arteries. The right renal artery arose from the false lumen with lack of blood flow to the right kidney. The left renal artery arose from the true lumen, but an intimal dissection flap appeared to be causing an intermittent stenosis of the left renal artery with compromised blood flow to the left kidney. Endovascular reconstruction with of the left renal artery with stent placement was performed. Hemodialysis was successfully discontinued six weeks after stent placement. CONCLUSION: Percutaneous intervention provides a promising alternative for patients with Type B aortic dissections when medical treatment will not improve the likelihood of meaningful recovery and surgery entails too great a risk. Nephrologists should therefore be aggressive in the workup of ischemic renal failure associated with aortic dissection as percutaneous intervention may reverse the effects of renal failure in this population

Malignant neuroendocrine tumour of the appendix in childhood with loco-regional lymph node invasion

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1006600359152743 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13000-015-0287-z) contains supplementary material, which is available to authorized users

Failure of functional imaging with gallium-68-DOTA-D-Phe1-Tyr3-octreotide positron emission tomography to localize the site of ectopic adrenocorticotropic hormone secretion: a case report

<p>Abstract</p> <p>Introduction</p> <p>The diagnostic efficacy of biochemical and imaging modalities for investigating the causes of Cushing's syndrome are limited. We report a case demonstrating the limitations of these modalities, especially the inability of functional imaging to help localize the site of ectopic adrenocorticotropic hormone secretion.</p> <p>Case presentation</p> <p>A 37-year-old Arabian woman presented with 12 months of progressive Cushing's syndrome-like symptoms. Biochemical evaluation confirmed adrenocorticotropic hormone -dependent Cushing's syndrome. However, the anatomical site of her excess adrenocorticotropic hormone secretion was not clearly delineated by further investigations. Magnetic resonance imaging of our patient's pituitary gland failed to demonstrate the presence of an adenoma. Spiral computed tomography of her chest only revealed the presence of a non-specific 7 mm lesion in her left inferobasal lung segment. Functional imaging, including a positron emission tomography scan using 18-fluorodeoxyglucose and gallium-68-DOTA-D-Phe1-Tyr3-octreotide, also failed to show increased metabolic activity in the lung lesion or in her pituitary gland. Our patient was commenced on medical treatment with ketoconazole and metyrapone to control the clinical features associated with her excess cortisol secretion. Despite initial normalization of her urinary free cortisol excretion rate, levels began to rise eight months after commencement of medical treatment. Repeated imaging of her pituitary gland, chest and pelvis again failed to clearly localize a source of her excess adrenocorticotropic hormone secretion. The bronchial nodule was stable in size on serial imaging and repeatedly reported as having a nonspecific appearance of a small granuloma or lymph node. We re-explored the treatment options and endorsed our patient's favored choice of resection of the bronchial nodule, especially given that her symptoms of cortisol excess were difficult to control and refractory. Subsequently, our patient had the bronchial nodule resected. The histological appearance of the lesion was consistent with that of a carcinoid tumor and immunohistochemical analysis revealed that the tumor stained strongly positive for adrenocorticotropic hormone. Furthermore, removal of the lung lesion resulted in a normalization of our patient's 24-hour urinary free cortisol excretion rate and resolution of her symptoms and signs of hypercortisolemia.</p> <p>Conclusion</p> <p>This case report demonstrates the complexities and challenges in diagnosing the causes of adrenocorticotropic hormone -dependent Cushing's syndrome. Functional imaging may not always localize the site of ectopic adrenocorticotropic hormone secretion.</p

A hierarchy of effective teaching and learning to acquire competence in evidenced-based medicine

BACKGROUND: A variety of methods exists for teaching and learning evidence-based medicine (EBM). However, there is much debate about the effectiveness of various EBM teaching and learning activities, resulting in a lack of consensus as to what methods constitute the best educational practice. There is a need for a clear hierarchy of educational activities to effectively impart and acquire competence in EBM skills. This paper develops such a hierarchy based on current empirical and theoretical evidence. DISCUSSION: EBM requires that health care decisions be based on the best available valid and relevant evidence. To achieve this, teachers delivering EBM curricula need to inculcate amongst learners the skills to gain, assess, apply, integrate and communicate new knowledge in clinical decision-making. Empirical and theoretical evidence suggests that there is a hierarchy of teaching and learning activities in terms of their educational effectiveness: Level 1, interactive and clinically integrated activities; Level 2(a), interactive but classroom based activities; Level 2(b), didactic but clinically integrated activities; and Level 3, didactic, classroom or standalone teaching. SUMMARY: All health care professionals need to understand and implement the principles of EBM to improve care of their patients. Interactive and clinically integrated teaching and learning activities provide the basis for the best educational practice in this field

Peroxisome Proliferator-Activated Receptor alpha (PPAR alpha) down-regulation in cystic fibrosis lymphocytes

Background: PPARs exhibit anti-inflammatory capacities and are potential modulators of the inflammatory response. We hypothesized that their expression and/or function may be altered in cystic fibrosis (CF), a disorder characterized by an excessive host inflammatory response. Methods: PPARα, β and γ mRNA levels were measured in peripheral blood cells of CF patients and healthy subjects via RT-PCR. PPARα protein expression and subcellular localization was determined via western blot and immunofluorescence, respectively. The activity of PPARα was analyzed by gel shift assay. Results: In lymphocytes, the expression of PPARα mRNA, but not of PPARβ, was reduced (-37%; p < 0.002) in CF patients compared with healthy persons and was therefore further analyzed. A similar reduction of PPARα was observed at protein level (-26%; p < 0.05). The transcription factor was mainly expressed in the cytosol of lymphocytes, with low expression in the nucleus. Moreover, DNA binding activity of the transcription factor was 36% less in lymphocytes of patients (p < 0.01). For PPARα and PPARβ mRNA expression in monocytes and neutrophils, no significant differences were observed between CF patients and healthy persons. In all cells, PPARγ mRNA levels were below the detection limit. Conclusion: Lymphocytes are important regulators of the inflammatory response by releasing cytokines and antibodies. The diminished lymphocytic expression and activity of PPARα may therefore contribute to the inflammatory processes that are observed in CF

A novel malaria vaccine candidate antigen expressed in Tetrahymena thermophila

Development of effective malaria vaccines is hampered by the problem of producing correctly folded Plasmodium proteins for use as vaccine components. We have investigated the use of a novel ciliate expression system, Tetrahymena thermophila, as a P. falciparum vaccine antigen platform. A synthetic vaccine antigen composed of N-terminal and C-terminal regions of merozoite surface protein-1 (MSP-1) was expressed in Tetrahymena thermophila. The recombinant antigen was secreted into the culture medium and purified by monoclonal antibody (mAb) affinity chromatography. The vaccine was immunogenic in MF1 mice, eliciting high antibody titers against both N- and C-terminal components. Sera from immunized animals reacted strongly with P. falciparum parasites from three antigenically different strains by immunofluorescence assays, confirming that the antibodies produced are able to recognize parasite antigens in their native form. Epitope mapping of serum reactivity with a peptide library derived from all three MSP-1 Block 2 serotypes confirmed that the MSP-1 Block 2 hybrid component of the vaccine had effectively targeted all three serotypes of this polymorphic region of MSP-1. This study has successfully demonstrated the use of Tetrahymena thermophila as a recombinant protein expression platform for the production of malaria vaccine antigens

Successful treatment of fusarium solani ecthyma gangrenosum in a patient affected by leukocyte adhesion deficiency type 1 with granulocytes transfusions

<p>Abstract</p> <p>Background</p> <p>Ecthyma gangrenosum (EG) manifests as a skin lesion affecting patients suffering extreme neutropenia and is commonly associated with <it>Pseudomonas aeruginosa </it>in immunocompromised patients. Leukocyte adhesion deficiency I (LAD I) which count among primary immunodeficiency syndromes of the innate immunity, is an autosomal recessive disorder characterized in its severe phenotype by a complete defect in CD18 expression on neutrophils, delayed cord separation, chronic skin ulcers mainly due to recurrent bacterial and fungal infections, leucocytosis with high numbers of circulating neutrophils and an accumulation of abnormally low number of neutrophils at sites of infection.</p> <p>Case Presentation</p> <p>We report at our knowledge the first case of a child affected by LAD-1, who experienced during her disease course a multi-bacterial and fungal EG lesion caused by <it>fusarium solani</it>. Despite targeted antibiotics and anti-fungi therapy, the lesion extended for as long as 18 months and only massive granulocytes pockets transfusions in association with G-CSF had the capacity to cure this lesion.</p> <p>Conclusion</p> <p>We propose that granulocytes pockets transfusions will be beneficial to heal EG especially in severely immunocompromised patients.</p