Towards Identifying Core Computational Literacy Concepts for Inclusion in a First-year General Engineering Course

In this paper, we describe an exploratory study to support efforts in revising first-year courses required for engineering students. It is common to include some form of introductory programming or spreadsheet computation topics in first-year courses. The inclusions of these topics is ostensibly to provide foundational computational skills needed in later courses. However, there are many challenges associated with teaching and learning these skills, the least of which is selecting which skills to include in the finite time allotted for a first-year introductory course that may also be tasked with teaching foundational problem solving and professional skills. This study is the first stage towards identifying a core set of skills for inclusion that would be relevant for most first-year students

Application of Hertz Vector Diffraction Theory to the Diffraction of Focused Gaussian Beams and Calculations of Focal Parameters

Hertz vector diffraction theory is applied to a focused TEM00 Gaussian light field passing through a circular aperture. The resulting theoretical vector field model reproduces plane-wave diffractive behavior for severely clipped beams, expected Gaussian beam behavior for unperturbed focused Gaussian beams as well as unique diffracted-Gaussian behavior between the two regimes. The maximum intensity obtainable and the width of the beam in the focal plane are investigated as a function of the clipping ratio between the aperture radius and the beam width in the aperture plane

Use of Michelson and Fabry-Perot interferometry for independent determination of the refractive index and physical thickness of wafers

We present a method to independently measure the refractive index and the thickness of materials having flat and parallel sides by using a combination of Michelson and Fabry-Perot interferometry techniques. The method has been used to determine refractive-index values in the infrared with uncertainties in the third decimal place and thicknesses accurate to within Ϯ5 m for materials at room and cryogenic temperatures. © 2005 Optical Society of America OCIS codes: 120.2230, 120.3180, 120.4290, 160.4760. The refractive index, n, and the thermo-optic coefficient, dn͞dT, of materials are often determined by one's interferometrically measuring the phase change that light undergoes in passing through a plane-parallel slab of the material. Because the phase change depends on the value of n as well as the slab thickness, d, to obtain accurate values of n and dn͞dT, it is important to know d accurately. FabryPerot etalon interferometry has been used to optically measure d, 5 but the precision of thickness measurements with this method is limited by the precision of the known refractive-index value. Recent research by Coppala et al. 6 demonstrated that independent values for n and d can be obtained with interferometry and a continuously tunable laser source. In this paper we demonstrate that the Michelson and the Fabry-Perot interferometric methods can be used sequentially to determine independent and absolute values of both the material's thickness and the material's refractive index over a wide range of temperatures of practical interest. The method does not require that either quantity be initially well known. With this method, both n and d can be determined by use of a fixed-wavelength laser source. First, by use of data from both experiments, the material's physical thickness is determined. Then the thickness value is used to determine the material's refractive index (and thermo-optic coefficient) with either of the interferometric methods. We present experimental verification of this method by measuring n and d for a range of common infrared materials at both room temperature and cryogenic temperatures. The intensity of a coherent collimated beam of light transmitted by a plane-parallel transparent plate is given by the Airy formula 7 : where I o is the incident intensity, r is the reflection coefficient for the electric field, and f is the phase difference accumulated by the light beam in a double traversal through the plate. As the sample is rotated in the path of the laser light, the net transmitted intensity will modulate owing to the changing phase, f . The angle-dependent phase difference between subsequent transmitted light paths through the sample is given by 7 f () ϭ 4nd cos t ϭ 4d ͙n 2 Ϫ sin 2 , where d is the sample thickness, is the laser wavelength, t is the angle of refraction, and is the angle of incidence of the laser path with respect to the normal of the sample surface

Performance of formulae based estimates of glomerular filtration rate for carboplatin dosing in stage 1 seminoma

<b>Background:</b> Single cycle carboplatin, dosed by glomerular filtration rate (GFR), is standard adjuvant therapy for stage 1 seminoma. Accurate measurement of GFR is essential for correct dosing. Isotopic methods remain the gold standard for the determination of GFR. Formulae to estimate GFR have improved the assessment of renal function in non-oncological settings. We assessed the utility of these formulae for carboplatin dosing.<p></p> <b>Methods:</b> We studied consecutive subjects receiving adjuvant carboplatin for stage 1 seminoma at our institution between 2007 and 2012. Subjects underwent 51Cr-ethylene diamine tetra-acetic acid (EDTA) measurement of GFR with carboplatin dose calculated using the Calvert formula. Theoretical carboplatin doses were calculated from estimated GFR using Chronic Kidney Disease-Epidemiology (CKD-EPI), Management of Diet in Renal Disease (MDRD) and Cockcroft–Gault (CG) formulae with additional correction for actual body surface area (BSA). Carboplatin doses calculated by formulae were compared with dose calculated by isotopic GFR; a difference <10% was considered acceptable.<p></p> <b>Results:</b> 115 patients were identified. Mean isotopic GFR was 96.9 ml/min/1.73 m2. CG and CKD-EPI tended to overestimate GFR whereas MDRD tended to underestimate GFR. The CKD-EPI formula had greatest accuracy. The CKD-EPI formula, corrected for actual BSA, performed best; 45.9% of patients received within 10% of correct carboplatin dose. Patients predicted as underdosed (13.5%) by CKD-EPI were more likely to be obese (p = 0.013); there were no predictors of the 40.5% receiving an excess dose.<p></p> <b>Conclusions:</b> Our data support further evaluation of the CKD-EPI formula in this patient population but clinically significant variances in carboplatin dosing occur using non-isotopic methods of GFR estimation. Isotopic determination of GFR should remain the recommended standard for carboplatin dosing when accuracy is essential.<p></p&gt

Correlations and Pair Formation in a Repulsively Interacting Fermi Gas

A degenerate Fermi gas is rapidly quenched into the regime of strong effective repulsion near a Feshbach resonance. The spin fluctuations are monitored using speckle imaging and, contrary to several theoretical predictions, the samples remain in the paramagnetic phase for arbitrarily large scattering length. Over a wide range of interaction strengths a rapid decay into bound pairs is observed over times on the order of 10\hbar/E_F, preventing the study of equilibrium phases of strongly repulsive fermions. Our work suggests that a Fermi gas with strong short-range repulsive interactions does not undergo a ferromagnetic phase transition

Frameworks for Estimating Causal Effects in Observational Settings: Comparing Confounder Adjustment and Instrumental Variables

To estimate causal effects, analysts performing observational studies in health settings utilize several strategies to mitigate bias due to confounding by indication. There are two broad classes of approaches for these purposes: use of confounders and instrumental variables (IVs). Because such approaches are largely characterized by untestable assumptions, analysts must operate under an indefinite paradigm that these methods will work imperfectly. In this tutorial, we formalize a set of general principles and heuristics for estimating causal effects in the two approaches when the assumptions are potentially violated. This crucially requires reframing the process of observational studies as hypothesizing potential scenarios where the estimates from one approach are less inconsistent than the other. While most of our discussion of methodology centers around the linear setting, we touch upon complexities in non-linear settings and flexible procedures such as target minimum loss-based estimation (TMLE) and double machine learning (DML). To demonstrate the application of our principles, we investigate the use of donepezil off-label for mild cognitive impairment (MCI). We compare and contrast results from confounder and IV methods, traditional and flexible, within our analysis and to a similar observational study and clinical trial

Towards Identifying Core Computational Literacy Concepts for Inclusion in a First-year General Engineering Course

In this paper, we describe an exploratory study to support efforts in revising first-year courses required for engineering students. It is common to include some form of introductory programming or spreadsheet computation topics in first-year courses. The inclusions of these topics is ostensibly to provide foundational computational skills needed in later courses. However, there are many challenges associated with teaching and learning these skills, the least of which is selecting which skills to include in the finite time allotted for a first-year introductory course that may also be tasked with teaching foundational problem solving and professional skills. This study is the first stage towards identifying a core set of skills for inclusion that would be relevant for most first-year students

Economics of Tourism and Transport: An Introduction

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Thermodynamic limits on oxygenic photosynthesis around M-dwarf stars: Generalized models and strategies for optimization

We explore the feasibility and potential characteristics of photosynthetic light-harvesting on exo-planets orbiting in the habitable zone of low mass stars ($< 1$ M$_{\odot}$). As stellar temperature, $T_{s}$, decreases, the irradiance maximum red-shifts out of the $400 \textrm{nm} \leq \lambda < 750$ nm range of wavelengths that can be utilized by \emph{oxygenic} photosynthesis on Earth. However, limited irradiance in this region does not preclude oxygenic photosynthesis and Earth's plants, algae and cyanobacteria all possess very efficient \emph{light-harvesting antennae} that facilitate photosynthesis in very low light. Here we construct general models of photosynthetic light-harvesting structures to determine how an oxygenic photosystem would perform in different irradiant spectral fluxes. We illustrate that the process of light-harvesting, capturing energy over a large antenna and concentrating it into a small \emph{reaction centre}, must overcome a fundamental \emph{entropic barrier}. We show that a plant-like antenna cannot be adapted to the light from stars of $T_{s}<3400$ K, as increasing antenna size offers diminishing returns on light-harvesting. This can be overcome if one introduces a slight \emph{enthalpic gradient}, to the antenna. Interestingly, this strategy appears to have been adopted by Earth's oxygenic cyanobacteria, and we conclude that \emph{bacterial} oxygenic photosynthesis is feasible around even the lowest mass M-dwarf stars.Comment: 5 Figures, submitted to Astrobiology and awaiting return of revie