1,225 research outputs found

    Goos-Haenchen induced vector eigenmodes in a dome cavity

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    We demonstrate numerically calculated electromagnetic eigenmodes of a 3D dome cavity resonator that owe their shape and character entirely to the Goos-Haenchen effect. The V-shaped modes, which have purely TE or TM polarization, are well described by a 2D billiard map with the Goos-Haenchen shift included. A phase space plot of this augmented billiard map reveals a saddle-node bifurcation; the stable periodic orbit that is created in the bifurcation corresponds to the numerically calculated eigenmode, dictating the angle of its "V". A transition from a fundamental Gaussian to a TM V mode has been observed as the cavity is lengthened to become nearly hemispherical.Comment: 4 pages, 4 figure

    Sorption kinetics for the removal of aldehydes from aqueous streams with extractant impregnated resins

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    The sorption kinetics for the removal aldehydes from aqueous solutions with Amberlite XAD-16 and MPP particles impregnated with Primene JM-T was investigated. A model, accounting for the simultaneous mass transfer and chemical reaction, is developed to describe the process. It is based on the analogy to the diffusion and reaction in a stagnant liquid sphere, but corrected for the porosity and particle properties influencing the diffusion. The developed model describes the kinetic behavior of the process in the low concentration region rather well. However, in the high concentration region, larger discrepancies are observed. Initially, the influence of the flow rate was investigated to eliminate the effect of the external mass transfer. The influence of the particle morphology was investigated for both physical and reactive sorption. Physical sorption experiments were used to determine the factor τ that takes the particle properties influencing the diffusion into account. It was shown that the diffusion is faster in XAD-16 than in MPP impregnated systems. Reaction rate constant kx was determined by fitting the model to the experimental data. Sorption of benzaldehyde appears to be significantly slower (kx ~ 10−4 l/mol s) than the sorption of pentanal (kx ~ 10−3 l/mol s) due to the slower chemical reaction. The influence of the particle size was investigated for the sorption of pentanal with XAD-16. It was observed that the particle size does influence the diffusion term, but does not have an effect on the reaction rate. On the other hand, the extractant loading influences the reaction rate slightly in the low concentration region, whereas the initial concentration of the solute has more pronounced effect

    On some Diophantine equations

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    High road mortality during female-biased larval dispersal in an iconic beetle

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    Animals often disperse from one habitat to another to access mates or suitable breeding sites. The costs and benefits of such movements depend, in part, on the dispersing individuals' phenotypes, including their sex and age. Here we investigated dispersal and road-related mortality in larvae of a bioluminescent beetle, the European common glow-worm, Lampyris noctiluca, in relation to habitat, sex and proximity of pupation. We expected these variables to be relevant to larval dispersal because adult females are wingless, whereas adult males fly when searching for glowing females. We found that dispersing glow-worm larvae were almost exclusively females and close to pupation. The larvae were often found on a road, where they were able to move at relatively high speeds, with a tendency to uphill orientation. However, each passing vehicle caused a high mortality risk, and we found large numbers of larvae run over by cars, especially close to covered, forest-like habitat patches. In contrast, adult females in the same area were most often found glowing in more open rocky and grassy habitats. These findings demonstrate an underappreciated ecological strategy, sex-biased dispersal at larval phase, motivated by different habitat needs of larvae and wingless adult females. The results are also consistent with roads being an ecological trap, facilitating dispersal and presumably females' signal visibility but causing severe larval mortality just before the reproductive stage. Hence, in addition to the previously recognised threats of urbanisation, even low traffic volumes have a high potential to negatively affect especially females of this iconic beetle. Significance statement Animals sometimes need to move from one habitat to another to find mating partners or breeding sites. We found this need to result in strongly female-biased larval dispersal in the European common glow-worm, a beetle known for the glow of wingless females that attract flying males to mate. Female larvae moving between habitats often used a road or trail but perished in high numbers when run over by cars. Hence, roads are likely to be ecological traps for the female glow-worm larvae, attracting them during dispersal, but causing grave mortality. The sex-biased larval dispersal, demonstrated in this study, is a poorly known ecological strategy that was found to be very risky in a human-modified landscape.Peer reviewe

    Evaluation and establishment of a ward-based geriatric liaison service for older urological surgical patients: Proactive care of Older People undergoing Surgery (POPS)-Urology.

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    OBJECTIVE: To assess the impact of introducing and embedding a structured geriatric liaison service, Proactive care of Older People undergoing Surgery (POPS)-Urology, using comprehensive geriatric assessment methodology, on an inpatient urology ward. PATIENTS AND METHODS: A phased quality improvement project was undertaken using stepwise interventions. Phase 1 was a before-and-after study with initiation of a daily board round, weekly multidisciplinary meeting, and targeted geriatrician-led ward rounds for elective and emergency urology patients aged ≥65 years admitted over two 1-month periods. Outcomes were recorded from medical records and discharge documentation, including length of inpatient stay, medical and surgical complications, and 30-day readmission and mortality rates. Phase 2 was a quality improvement project involving Plan-Do-Study-Act cycles and qualitative staff surveys in order to create a Geriatric Surgical Checklist (GSCL) to standardize the intervention in Phase 1, improve equity of care by extending it to all ages, improve team-working and streamline handovers for multidisciplinary staff. RESULTS: Phase 1 included 112 patients in the control month and 130 in the intervention month. The length of inpatient stay was reduced by 19% (mean 4.9 vs 4.0 days; P = 0.01), total postoperative complications were lower (risk ratio 0.24 [95% confidence interval 0.10, 0.54]; P = 0.001). A non-significant trend was seen towards fewer cancellations of surgery (10 vs 5%; P = 0.12) and 30-day readmissions (8 vs 3%; P = 0.07). In Phase 2, the GSCL was created and incrementally improved. Questionnaires repeated at intervals showed that the GSCL helped staff to understand their role better in multidisciplinary meetings, improved their confidence to raise issues, reduced duplication of handovers and standardized identification of geriatric issues. Equity of care was improved by providing the intervention to patients of all ages, despite which the time taken for the daily board round did not lengthen. CONCLUSION: This is the first known paper describing the benefits of daily proactive geriatric intervention in elective and emergency urological surgery. The results suggest that using a multidisciplinary team board round helps to facilitate collaborative working between surgical and geriatric medicine teams. The GSCL enables systematic identification of patients who require a focused comprehensive geriatric assessment. There is potential to transfer the GSCL package to other surgical specialties and hospitals to improve postoperative outcomes

    Superconducting and Normal State Properties of Neutron Irradiated MgB2

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    We have performed a systematic study of the evolution of the superconducting and normal state properties of neutron irradiated MgB2_2 wire segments as a function of fluence and post exposure annealing temperature and time. All fluences used suppressed the transition temperature, Tc, below 5 K and expanded the unit cell. For each annealing temperature Tc recovers with annealing time and the upper critical field, Hc2(T=0), approximately scales with Tc. By judicious choice of fluence, annealing temperature and time, the Tc of damaged MgB2 can be tuned to virtually any value between 5 and 39 K. For higher annealing temperatures and longer annealing times the recovery of Tc tends to coincide with a decrease in the normal state resistivity and a systematic recovery of the lattice parameters.Comment: Updated version, to appear in Phys. Rev.

    Plasma inflammatory cytokines and survival of pancreatic cancer patients.

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    OBJECTIVES: Inflammation and inflammatory conditions have been associated with pancreatic cancer risk and progression in a number of clinical, epidemiological, and animal model studies. The goal of the present study is to identify plasma markers of inflammation associated with survival of pancreatic cancer patients, and assess their joint contribution to patient outcome. METHODS: We measured circulating levels of four established markers of inflammation (C-reactive protein (CRP), interleukin-6 (IL-6), soluble tumor necrosis factor receptor type II (sTNF-RII), and macrophage inhibitory cytokine-1 (MIC-1)) in 446 patients enrolled in an ongoing prospective clinic-based study. Hazard ratios (HRs) and 95% confidence intervals (CI) for death were estimated using multivariate Cox proportional hazards models. RESULTS: Overall mortality was significantly increased in patients in the top quartile of CRP (HR = 2.52, 95% CI: 1.82-3.49), IL-6 (HR = 2.78, 95% CI: 2.03-3.81), sTNF-RII (HR = 2.00, 95% CI: 1.46-2.72), and MIC-1 (HR = 2.53, 95% CI: 1.83-3.50), compared to those in the bottom quartile (P-trend CONCLUSION: Individual elevated plasma inflammatory cytokines are associated with significant and dramatic reductions in pancreatic cancer patient survival. Furthermore, we observed an independent combined effect of those cytokines on patient survival, suggesting that multiple inflammatory pathways are likely involved in PDAC progression. Future research efforts to target the inflammatory state using combination strategies in pancreatic cancer patients are warranted
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