A general low frequency acoustic radiation capability for NASTRAN

A new capability called NASHUA is described for calculating the radiated acoustic sound pressure field exterior to a harmonically-excited arbitrary submerged 3-D elastic structure. The surface fluid pressures and velocities are first calculated by coupling a NASTRAN finite element model of the structure with a discretized form of the Helmholtz surface integral equation for the exterior fluid. After the fluid impedance is calculated, most of the required matrix operations are performed using the general matrix manipulation package (DMAP) available in NASTRAN. Far field radiated pressures are then calculated from the surface solution using the Helmholtz exterior integral equation. Other output quantities include the maximum sound pressure levels in each of the three coordinate planes, the rms and average surface pressures and normal velocities, the total radiated power and the radiation efficiency. The overall approach is illustrated and validated using known analytic solutions for submerged spherical shells subjected to both uniform and nonuniform applied loads

Cost-effectiveness analysis of endoscopic eradication therapy for treatment of high-grade dysplasia in Barrett's esophagus

AIM: The aim was to evaluate the cost-effectiveness of endoscopic eradication therapy (EET) with combined endoscopic mucosal resection and radiofrequency ablation for the treatment of high-grade dysplasia (HGD) arising in patients with Barrett's esophagus compared with endoscopic surveillance alone in the UK. MATERIALS & METHODS: The cost-effectiveness model consisted of a decision tree and modified Markov model. A lifetime time horizon was adopted with the perspective of the UK healthcare system. RESULTS: The base case analysis estimates that EET for the treatment of HGD is cost-effective at a GB£20,000 cost-effectiveness threshold compared with providing surveillance alone for HGD patients (incremental cost-effectiveness ratio: GB£1272). CONCLUSION: EET is likely to be a cost-effective treatment strategy compared with surveillance alone in patients with HGD arising in Barrett's esophagus in the UK

Experimental evidence of a {\phi} Josephson junction

We demonstrate experimentally the existence of Josephson junctions having a doubly degenerate ground state with an average Josephson phase \psi=\pm{\phi}. The value of {\phi} can be chosen by design in the interval 0<{\phi}<\pi. The junctions used in our experiments are fabricated as 0-{\pi} Josephson junctions of moderate normalized length with asymmetric 0 and {\pi} regions. We show that (a) these {\phi} Josephson junctions have two critical currents, corresponding to the escape of the phase {\psi} from -{\phi} and +{\phi} states; (b) the phase {\psi} can be set to a particular state by tuning an external magnetic field or (c) by using a proper bias current sweep sequence. The experimental observations are in agreement with previous theoretical predictions

Respiratory symptoms in people living with HIV and the effect of antiretroviral therapy: a systematic review and meta-analysis

BACKGROUND: Antiretroviral therapy (ART) has significantly altered the pattern of acute and chronic HIV-related disease. However, it is not clear what this means in terms of respiratory symptoms. We sought to investigate the association between HIV status and respiratory symptoms and how these have changed with the availability of ART. METHODS: We searched Cochrane, Medline and Embase databases for studies published between 1946 and August 2015 comparing the prevalence of respiratory symptoms in populations with and without HIV infection. We undertook random effects meta-analysis of the main symptoms reported. We studied heterogeneity and completed sensitivity analyses and funnel plots. RESULTS: From 5788 unique references identified, 24 papers provided relevant data: 18 documented the prevalence of cough and 11 examined the prevalence of breathlessness among other symptoms reported. Compared with the HIV negative, people living with HIV (PLWH) were more likely to have respiratory symptoms with pooled ORs for the prevalence of cough of 3.05 (95% CI 2.24 to 4.16) in resource-limited populations without access to ART; 2.18 (1.56 to 3.18) in resource-rich populations without access to ART and 1.11 (0.99 to 1.24) in resource-rich populations with access to ART. In resource-rich settings, although the availability of ART was associated with a reduction in the difference between HIV-positive and HIV-negative individuals, PLWH were more likely to report breathlessness, OR 1.39 (95% CI 1.11 to 1.73). CONCLUSIONS: Respiratory symptoms are more common in PLWH than controls. This association persists although at a reduced level in populations with access to ART

On the Complexity of Searching in Trees: Average-case Minimization

We focus on the average-case analysis: A function w : V -> Z+ is given which defines the likelihood for a node to be the one marked, and we want the strategy that minimizes the expected number of queries. Prior to this paper, very little was known about this natural question and the complexity of the problem had remained so far an open question. We close this question and prove that the above tree search problem is NP-complete even for the class of trees with diameter at most 4. This results in a complete characterization of the complexity of the problem with respect to the diameter size. In fact, for diameter not larger than 3 the problem can be shown to be polynomially solvable using a dynamic programming approach. In addition we prove that the problem is NP-complete even for the class of trees of maximum degree at most 16. To the best of our knowledge, the only known result in this direction is that the tree search problem is solvable in O(|V| log|V|) time for trees with degree at most 2 (paths). We match the above complexity results with a tight algorithmic analysis. We first show that a natural greedy algorithm attains a 2-approximation. Furthermore, for the bounded degree instances, we show that any optimal strategy (i.e., one that minimizes the expected number of queries) performs at most O(\Delta(T) (log |V| + log w(T))) queries in the worst case, where w(T) is the sum of the likelihoods of the nodes of T and \Delta(T) is the maximum degree of T. We combine this result with a non-trivial exponential time algorithm to provide an FPTAS for trees with bounded degree

Delayed-onset disseminated BCG disease causing a multi-system illness with fatal mycotic aortic aneurysm

CASE: We report a case of disseminated BCG infection, diagnosed two years after BCG infusion for bladder cancer. Our patient, a 74-year-old male, was referred with an 18-month history of fevers, weight loss and intermittent confusion. Prior to referral, the patient had multiple hospital admissions for evaluation of fever of unknown origin, confusion, and fatigue. He was treated for several acute infections, whilst extensive investigations did not identify a focal cause of the persistent fever. During this period two aneurysms, iliac and aortic, were found and stented. Both were presumed mycotic, but no positive microbiology arose from either. He presented again with fever and confusion and was found to have a left sided pleural effusion, which was drained, and broad-spectrum antibiotics started, but his fever and inflammatory markers did not settle. Mycobacterium tuberculosis PCR on a pleural fluid sample returned a positive result, and later cultures from the same fluid grew Mycobacterium species which whole genome sequencing identified as Mycobacterium Bacillus Calmette-Guérin (BCG). Despite a number of adverse events with anti-BCG medications, the patient was established on four medications (rifampicin/isoniazid/ethambutol/levofloxacin) with symptomatic improvement. He re-presented four months later with abdominal pain and was found to have an inoperable leaking thoracic aortic sac from deterioration of his mycotic aneurysm. Following discussion with the patient and his family he was managed palliatively and died two days later. DISCUSSION: The learning points from this case are to consider disseminated BCG in patients presenting with pyrexia of unknown origin following reported intravesical BCG treatment for bladder malignancy in the years prior to presentation. Mycotic aneurysms are a rare but serious complication of disseminated BCG with a high mortality

The Synthesis, Characterisation and Potential of Eu 3+ Doped Molybdate Phosphors for White Light Emitting Diodes

A wide variety of Eu3+ doped molybdate phosphors were synthesised using the solid state reaction route and their photoluminescent properties were compared. Their crystal structures were investigated. A relationship between cell size and emission intensity was apparent. The implications of this for phosphor design are discussed.The authors are grateful to the Technology Strategy Board (TSB) (UK) for financial funding in the form of TSB Technology programs for the NovelLEDs program TP/6/EPH/6/S/K2522J and the EPSRC for funding the PURPOSE program

Helping education undergraduates to use appropriate criteria for evaluating accounts of motivation

The aim of the study was to compare students in a control group with those in a treatment group with respect to evaluative comments on psychological accounts of motivation. The treatment group systematically scrutinized the nature and interpretation of evidence that supported different accounts, and the assumptions, logic, coherence and clarity of accounts. Content analysis of 74 scripts (using three categories) showed that the control group students made more assertions than either evidential or evaluative points, whereas the treatment group used evaluative statements as often as they used assertion. The findings provide support for privileging activities that develop understanding of how knowledge might be contested, and suggest a need for further research on pedagogies to serve this end. The idea is considered that such understanding has a pivotal role in the development of critical thinking