Search

The physics of intersubband transitions in a patterned inverse quantum dot (IQD) array is analyzed. The studies have shown that the polarization dependence of intersubband absorption is controlled by appropriate design of the IQD array geometry.

The effect of nanopore lattice geometry, material parameters, and temperature on the density of states and intraband energy gaps in an ordered nanopore array diode laser is studied analytically. An improved fabrication process is described for increasing the peak gain achievable in the nanopore laser by a factor of 3 based on the simulation results.

The relationship between the upper cladding thickness and residual thickness and the threshold current, intrinsic loss and the far-field lateral modal characteristics is examined. The results are used for designing efficient devices and waveguides in photonic integrated circuits by using asymmetric cladding ridge waveguides designs for the active and passive devices and are applied to the optimization of any ridge waveguide laser.

The capabilities of the effective-medium approximation (EMA) and alloy models are examined to describe multilayers samples with gradual interfaces by analyzing spectroscopic ellipsometric (SE) data of two AlGaAs samples. Results described the types of errors encountered with different models and have shown that SE data can provide information about the graded regions.

Background/Aims: Acute kidney injury (AKI) following admission to hospital is associated with increased mortality, morbidity and length of stay. Factors that predispose patients to AKI frequently co-exist. The precise description of their representation in unselected admissions could help define mechanistic inter-relationships and optimise risk stratification strategies. Our aim was therefore to define precisely, using electronically available data, the variables that are associated with AKI. Methods: A cohort study of 112,987 emergency admissions to an urban academic medical centre between 2006 and 2010 was performed. Post-admission AKI was defined using KDIGO aligned, proportionate changes in serum creatinine, denominated by the first measured. AKI correlated with co-morbidities, medications received and the C-reactive protein concentration (CRP). Results: The relationship between post-admission AKI and putative risk factors was defined in univariate and multivariate analyses. Inclusion of CRP in multivariate analyses significantly reduced the strength of association between some co-variables such as radiological contrast and gentamicin administration but not others. Conclusion: The effect of CRP in these analyses supports the role of systemic inflammation in susceptibility to post-admission AKI. It accounts for the greater part of univariate associations between AKI and some nephrotoxic agents, placing the risk attributable to their use in context. Quantification of the systemic inflammatory response may have utility in AKI risk stratification, integrating various determinants of susceptibility. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background:Interprofessional education (IPE) is one component of the medical education curriculum and there is a growing interest in the use of e-learning to support this area of the curriculum. The aims of this research were to undertake a pilot feasibility and efficacy trial to test the feasibility of undertaking experimental research in a medical education setting and the efficacy of an e-learning intervention (online simulation) to support IPE.Design and methods:The design of the study was a pragmatic pilot trial with a waiting list. The participants were third-year medical undergraduate students. The trial involved random allocation to either access or no access to online simulations in two strata. The outcome assessments were embedded items in the end-of-year summative exam.Results:From the third-year cohort of 407 students, 253 were eligible to participate in the trial and 152 were excluded. For stratum 1, of 162 eligible students, 88 consented, 25 declined and 49 did not respond. For stratum 2, of 91 eligible students, 37 consented, 17 declined and 37 did not respond. For stratum 1, there was no significant difference in performance on the embedded questions between intervention and control groups. The effect size was −0.10, 95% confidence interval (CI) −0.52 to 0.33. Similarly, for stratum 2, no significant differences between intervention and control groups were apparent. The effect size was 0.22, CI −0.46 to 0.90. When the results for strata 1 and 2 were combined in a meta-analysis the pooled effect size was −0.01 95% CI −0.36 to 0.35p = 0.98. This indicates no statistically significant difference between the simulation and no-simulation groups.Discussion:Recruitment to the trial fell short of what was expected. Similarly, student retention in the trial was lower than anticipated, with just under half of the students who consented to take part actually engaging with the intervention. The trial found no statistically significant difference in efficacy between the intervention and non-intervention groups. However, this finding must be interpreted with caution due to the small sample size.Conclusions:This study tested the recruitment and retention of third-year medical students to a pilot feasibility trial of a Web-based learning package. The promise of the intervention was also investigated using questions embedded in a summative assessment. Whilst such trials are feasible and acceptable, conducting a study to CONSORT standards requires measures to encourage student engagement. [ABSTRACT FROM AUTHOR]

We report results of both strain-driven surface segregation of indium from InGaAs thin films as well as selective area epitaxy of InAs quantum dots using these films. InAs segregation from an underlying InGaAs film allows for preferential growth of quantum dots when additional InAs is deposited. By using standard lithography techniques, a two-step selective growth process for quantum dots is achieved. Furthermore, by utilizing self-assembled nanostructures as a template, selective growth of coalesced wires and dots with 100-nm feature sizes are realized. [ABSTRACT FROM PUBLISHER]

The incorporation of intentional strain in heterostructure lasers was almost unheard of a decade ago or so and considered a problem to be avoided. Advances in both epitaxial crystal growth technology and the understanding of the physics and reliability of these materials have led to a remarkable increase in the commercial use of strained-layer lasers. The industry has benefited from an increase in the available range of emission wavelengths from quantum-well diode lasers and dramatic improvement in their time-zero performance. In the paper, we review the characteristics of strained-layer InGaAs quantum-well heterostructure lasers that have resulted in the emergence of this important technology [ABSTRACT FROM PUBLISHER]

The distributed Bragg pulse shaper (DBPS) is a series of electrically switchable Bragg mirrors on a semiconductor waveguide. The DBPS encodes data packets using parallel electrical signals to set the states of the Bragg mirrors. A broad-band source pulse then probes the device to generate a high bandwidth serial wavepacket from the train of partially reflecting mirrors. This paper describes a DBPS constructed in AlGaAs. Using this device and a mode-locked Ti:sapphire laser, we create a 4-bit packet with 0.37 Tb/s burst bit rate and are demonstrate for the first time that bits in the wavepacket can be switched by electrical modulation of individual Bragg segments. We also describe a model collaborating the observed data [ABSTRACT FROM PUBLISHER]