Underwater single crystal piezocomposite transducer with extended usable frequency band.

A single crystal/epoxy 1-3 composite plate transducer with air backing and two acoustic matching layers was modelled, fabricated and compared to a similar PZT transducer. For the relevant underwater applications, the usable frequency band is restricted by reactive electrical power. The design goal was to provide an underwater transmitter that could be operated over a wide range of frequencies, but not necessarily create a single pulse spanning the entire frequency band. The thicknesses and the characteristic acoustic impedances of the matching layers were therefore optimized for a wide passband rather than a maximally flat passband. The resulting single crystal transducer had reactive power below 50 % in a frequency band 132 % wide relative to the center frequency.

Optimization of Matching Layers to Extend the Usable Frequency Band for Underwater Single-Crystal Piezocomposite Transducers.

The ongoing robotic revolution in oceanic science puts new requirements on sonar technology. Small platforms require compact multi-purpose transducers, with strict requirements on power consumption and heat dissipation. Introducing single-crystal ferroelectrics as the active material of the transmitter can be one way of meeting the new requirements. The large electromechanical coupling coefficient of single crystals can enable an extension of the usable frequency band compared to conventional PZT. For the applications considered in this work, the usable frequency band is restricted by both the transmitted acoustic power and the reactive electrical power. Single crystals as the active materials can double the usable band, but the acoustic matching required for this can be difficult to obtain in practice. We investigated an air-backed, plane 1-3 composite transducer, matched to water by acoustic matching layers. For many applications, the diversity provided by a large usable frequency range is more important than a flat acoustic power response, and the transducer can be used far beyond the -3-dB limit. We defined the usable band by requiring maximum -12-dB ripple in transmitted acoustic power and maximum 50% reactive power. The matching layers were optimized to maximize the usable band according to this definition, in contrast to the conventional approach where matching layers are optimized for maximally flat response. Under the chosen definitions, our modeling showed that with a single crystal as the active material we could achieve 188% usable frequency band relative to the resonance frequency, compared to 121% for a PZT.

Checkpoint inhibitors in pancreatic cancer.

INTRODUCTION: Immune checkpoint inhibitors, targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and the programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) pathways have shown remarkable potential in several types of cancer. In this review we summarize published and ongoing studies on checkpoint inhibitors in pancreatic cancer (PC). METHODS: We conducted a systematic literature search using Medline and Embase up to November 2018; additional data from a search on clinicaltrials.gov were included. Endpoints of interest encompassed overall survival (OS), progression free survival (PFS) and response rates. RESULTS: Full-length articles constituted a minority of included records. Furthermore, few patients were enrolled, and only few phase II studies were identified. Disappointing limited activity was demonstrated with single-agent checkpoint inhibitors in PC. A small number of studies on combination therapy showed promise with regards to response. But overall, PC patients treated with checkpoint inhibitors were not shown to elicit improvement in response rates or overall survival. CONCLUSION: Checkpoint inhibition monotherapy has failed to elicit efficacy in patients with pancreatic cancer. Combination regimens including chemotherapy have shown initial promise, but these results need to be verified. Numerous studies on checkpoint inhibition in PC are ongoing.

Validity of the European short list of respiratory diseases: a 40-year autopsy study.

The predictors of autopsy and the accuracy of European short list (E) codes of respiratory diseases lack recent knowledge. A 10% random sample (n=6811) of inhabitants of Bergen, Norway, aged 20-70 years, was invited to participate in a survey in 1965-1971 (participation rate 83%). By December 31, 2005, 4387 (64%) participants had died and 1163 (27% of the deceased) had been given an autopsy. Causes of death were tuberculosis (E02, 0.2%), lung malignancy (E15, 3.5%), influenza (E38, 0.2%), pneumonia (E39, 6.5%) and chronic lower respiratory diseases (E40, 3.2%). Male sex, early deaths in the surveillance period and E15 were positive predictors of an autopsy examination, whereas old age and E39 were strong negative predictors. Among those referred for a post mortem examination, the cause of death was verified as tuberculosis in 0.3%, lung cancer in 8.1%, acute pneumonia in 2.0% and chronic obstructive lung diseases in 4.9%. Cohen's kappa coefficients (E codes versus autopsy) were 0.91 (95% CI 0.86-0.96) for E15, 0.37 (95% CI 0.20-0.54) for E39 and 0.65 (95% CI 0.54-0.76) for E40. These findings matter when deaths from respiratory diseases are used as end-points in epidemiological association studies and clinical trials.

Nutritional risk profile in a university hospital population.

BACKGROUND & AIMS: The prevalence of nutritional risk varies according to several factors. We aimed to determine the nutritional risk profile in a large Norwegian hospital population, specifically by age, disease category and hospital department. METHODS: Nutritional surveys are performed routinely at Haukeland University Hospital, Norway. During eight surveys in 2008-2009, 3279 patients were categorized according to the Nutritional Risk Screening tool (NRS 2002). RESULTS: The overall prevalence of nutritional risk was 29%, highest in patients with infections (51%), cancer (44%) and pulmonary diseases (42%), and in the departments of intensive care (74%), oncology (49%) and pulmonology (43%). Further, nutritional risk was identified in 40% of patients aged ≥80 years compared to 21% of age <40 years and 35% of patients with emergency admissions compared to 19% with elective admissions. Related to the tool components, nutritional risk was most common in patients with low BMI (<20.5 kg/m(2)) (95%) and/or high comorbidity (>7 diagnoses) (45%). However it was also high in patients with BMI ≥25 kg/m(2) (12%) and in those with fewer than 7 diagnoses (26%). CONCLUSIONS: Nutritional risk was most common among patients with high age, low BMI, more comorbidity, and with infections, cancer or pulmonary diseases, and patients who were discharged to nursing homes. However, the highest number of patients at nutritional risk had BMI in the normal or overweight range, were 60-80 years old, and were found in departments of general medicine or surgery. Importantly, younger patients and overweight patients were also affected. Thus, nutritional risk screening should be performed in the total patient population in order to identify, within this heterogeneous group of patients, those at nutritional risk.

The nutritional strategy: four questions predict morbidity, mortality and health care costs.

BACKGROUND: Nutritional care for hospital in-patients is potentially important but challenging. OBJECTIVE: To investigate the association between nutritional status and clinical outcomes. METHODS: Eight prevalence surveys were performed at Haukeland University Hospital, Norway, during 2008-2009. In total 3279 patients were classified as being at nutritional risk or not according to the Nutritional Risk Screening (NRS 2002) tool. The initial four questions of NRS 2002 assess dietary intake, weight loss, body mass index (BMI) and illness severity. RESULTS: The overall prevalence of nutritional risk was 29%. Adjusted mean days for hospitalisation was 8.3 days for patients at nutritional risk and 5.0 days for patients not at risk (p < 0.001). In adjusted models, patients at nutritional risk had increased one-year mortality (OR 4.07, 95% CI 2.90-5.70), morbidity (OR 1.59, 95% CI 1.18-2.13), and were 1.24 (95% CI 1.16-1.32) times more likely to have had a new admission during the three previous years and the one subsequent year, compared to patients not at risk. A 'positive' response to the initial four questions was associated with increased risk of morbidity and mortality. Patients with a reduced dietary intake during the last weeks had OR 1.72 (95% CI 1.03-2.85) for one-year mortality. Patients with a positive answer on all the initial four questions had ten times increased risk for mortality the following year, OR 13.0 (95% CI 4.52-37.6). CONCLUSION: The four initial questions of the NRS 2002 robustly identify nutritional risk and were strong predictors of hospitalisation, morbidity and most importantly mortality among hospitalised patients. Thus, these simpler and short questions are robust indicators for subsequent poor outcomes.