A variant of nested dissection for solving n by n grid problems

Nested dissection orderings are known to be very effective for solving the sparse positive definite linear systems which arise from n by n grid problems. In this paper nested dissection is shown to be the final step of incomplete nested dissection, an ordering which corresponds to the premature termination of dissection. Analyses of the arithmetic and storage requirements for incomplete nested dissection are given, and the ordering is shown to be competitive with nested dissection under certain conditions

A case of acute aortic dissection type b associated with cushing's syndrome

We report a case of a 63-year-old man, with a previous history of hypertension and glucose intolerance associated troncular obesity that was emergently admitted to our Institution for evaluation of a severe, constant posterior chest pain which radiated anteriorly and dyspnoea with a suspected diagnosis of acute aortic dissection. A CT scan of thorax and abdomen demonstrated a dissection starting just below left succlavian artery and extending downward to the left renal artery, involving the celiac tripod and superior mesenteric artery. The dissection was classified as Stanford B, De Bakey III. Moreover, CT scan of abdomen revealed incidentally a left adrenal tumor of 25 mm of diameter. An emergent prosthetic graft was placed just below the origin of the left succlavian artery up-to the diaphragmatic hiatus. Furthermore, a diagnostic evaluation of the mass revealed an increase of cortisol production, and a diagnosis of Cushing's syndrome was done and the patient underwent an adrenalectomy via laparotomic approach. We report an association of acute aortic dissection of acute aortic dissection type B associated to Cushing's syndrome. Cushing's syndrome; Adrenocortical adenoma; Aortic dissection type B

Postablation Right Atrial Dissection in Ebstein's Anomaly.

• Right atrial dissection is a potentially life-threatening complication after ablation. • Hemodynamic instability may occur and can be rapidly progressive. • Agitated saline contrast echocardiography may help diagnose intracardiac dissection

Spontaneous Coronary Artery Dissection: A Case Series of 9 Patients With Literature Review.

Spontaneous coronary artery dissection is an increasingly recognized nonatherosclerotic cause of acute coronary syndrome. Reports regarding the prognosis and natural history of this disease are limited. In addition to the diagnostic difficulty, this condition poses a significant therapeutic challenge due to the lack of specific management guidelines. We present here a case series of 9 patients with spontaneous coronary artery dissection. Additionally, this article reviews the incidence, clinical characteristics, risk factors, diagnostic modalities, therapeutic approaches, and patterns of recurrence in patients with spontaneous coronary artery dissection

Advances in procedural techniques--antegrade.

There have been many technological advances in antegrade CTO PCI, but perhaps most importantly has been the evolution of the "hybrid' approach where ideally there exists a seamless interplay of antegrade wiring, antegrade dissection re-entry and retrograde approaches as dictated by procedural factors. Antegrade wire escalation with intimal tracking remains the preferred initial strategy in short CTOs without proximal cap ambiguity. More complex CTOs, however, usually require either a retrograde or an antegrade dissection re-entry approach, or both. Antegrade dissection re-entry is well suited to long occlusions where there is a healthy distal vessel and limited "interventional" collaterals. Early use of a dissection re-entry strategy will increase success rates, reduce complications, and minimise radiation exposure, contrast use as well as procedural times. Antegrade dissection can be achieved with a knuckle wire technique or the CrossBoss catheter whilst re-entry will be achieved in the most reproducible and reliable fashion by the Stingray balloon/wire. It should be avoided where there is potential for loss of large side branches. It remains to be seen whether use of newer dissection re-entry strategies will be associated with lower restenosis rates compared with the more uncontrolled subintimal tracking strategies such as STAR and whether stent insertion in the subintimal space is associated with higher rates of late stent malapposition and stent thrombosis. It is to be hoped that the algorithms, which have been developed to guide CTO operators, allow for a better transfer of knowledge and skills to increase uptake and acceptance of CTO PCI as a whole

Medical Student Dissection of Cadavers Improves Performance on Practical Exams but not on the NBME Anatomy Subject Exam

We have examined whether cadaver dissection by first year medical students (MIs) affected their performance in two test measures: the NBME Gross Anatomy and Embryology Subject Exam (dissection-relevant questions only), and practical exams given at the end of each major section within the course. The dissections for the entire course were divided into 18 regional dissection units and each student was assigned to dissect one third of the regional units; the other two-thirds of the material was learned from the partner-prosected cadavers. Performance for each student on the exams was then assessed as a function of the regions those students actually dissected. While the results indicated a small performance advantage for MIs answering questions on material they had dissected on the NBME Subject Exam questions relevant to dissection (78-88% of total exam), the results were not statistically significant. However, a similar, small performance advantage on the course practical exams was highly significant

Standard methods for Apis mellifera anatomy and dissection

An understanding of the anatomy and functions of internal and external structures is fundamental to many studies on the honey bee Apis mellifera. Similarly, proficiency in dissection techniques is vital for many more complex procedures. In this paper, which is a prelude to the other papers of the COLOSS BEEBOOK, we outline basic honey bee anatomy and basic dissection techniques

Interventions for the treatment of oral and oropharyngeal cancers: surgical treatment.

BACKGROUND: Surgery is an important part of the management of oral cavity cancer with regard to both the removal of the primary tumour and removal of lymph nodes in the neck. Surgery is less frequently used in oropharyngeal cancer. Surgery alone may be treatment for early stage disease or surgery may be used in combination with radiotherapy, chemotherapy and immunotherapy/biotherapy. There is variation in the recommended timing and extent of surgery in the overall treatment regimens of people with these cancers. OBJECTIVES: To determine which surgical treatment modalities for oral cavity and oropharyngeal cancers result in increased overall survival, disease free survival, progression free survival and reduced recurrence. SEARCH STRATEGY: The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 17 February 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to 17 February 2011) and EMBASE via OVID (1980 to 17 February 2011). There were no restrictions regarding language or date of publication. SELECTION CRITERIA: Randomised controlled trials where more than 50% of participants had primary tumours of the oral cavity or oropharynx, and which compared two or more surgical treatment modalities or surgery versus other treatment modalities. DATA COLLECTION AND ANALYSIS: Data extraction and assessment of risk of bias was undertaken independently by two or more review authors. Study authors were contacted for additional information as required. Adverse events data were collected from published trials. MAIN RESULTS: Seven trials (n = 669; 667 with cancers of the oral cavity) satisfied the inclusion criteria, but none were assessed as low risk of bias. Trials were grouped into three main comparisons. Four trials compared elective neck dissection (ND) with therapeutic neck dissection in patients with oral cavity cancer and clinically negative neck nodes, but differences in type of surgery and duration of follow-up made meta-analysis inappropriate. Three of these trials reported overall and disease free survival. One trial showed a benefit for elective supraomohyoid neck dissection compared to therapeutic ND in overall and disease free survival. Two trials found no difference between elective radical ND and therapeutic ND for the outcomes of overall survival and disease free survival. All four trials found reduced locoregional recurrence following elective ND.A further two trials compared elective radical ND with elective selective ND and found no difference in overall survival, disease free survival or recurrence. The final trial compared surgery plus radiotherapy to radiotherapy alone but data were unreliable because the trial stopped early and there were multiple protocol violations.None of the trials reported quality of life as an outcome. Two trials, evaluating different comparisons reported adverse effects of treatment. AUTHORS' CONCLUSIONS: Seven included trials evaluated neck dissection surgery in patients with oral cavity cancers. The review found weak evidence that elective neck dissection of clinically negative neck nodes at the time of removal of the primary tumour results in reduced locoregional recurrence, but there is insufficient evidence to conclude that elective neck dissection increases overall survival or disease free survival compared to therapeutic neck dissection. There is very weak evidence from one trial that elective supraomohyoid neck dissection may be associated with increased overall and disease free survival. There is no evidence that radical neck dissection increases overall survival compared to conservative neck dissection surgery. Reporting of adverse events in all trials was poor and it was not possible to compare the quality of life of patients undergoing different surgeries