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The radial forearm free flap (RFFF) is widely used for oral reconstruction. The superficial circumflex iliac artery perforator (SCIP) flap is an increasingly utilized alternative. The cases of 165 patients who received either an RFFF or SCIP flap for oral reconstruction at Chris O'Brien Lifehouse, Sydney were reviewed. The aim was to report on patient, pathology, treatment, and outcome variables and to compare these between the two flap groups. A RFFF was used in 126 patients and a SCIP flap in 39 patients. SCIP flap patients were younger (P 0.001) and had shorter operative times (P 0.001), shorter anaesthetic times (P 0.001), and more frequent recipient site dehiscence (P = 0.005) when compared to RFFF patients. The SCIP flap was significantly less frequently used for composite resections including bone when compared to the RFFF (P 0.001). The primary site distribution was more even for RFFF patients (P 0.001). There were no SCIP flap failures; three RFFF failures occurred. SCIP flaps performed comparably in terms of operative and clinical outcomes. Most SCIP flaps were utilized in younger patients with partial glossectomy defects.

There are around 2,500 new cases of oral cavity squamous cell carcinoma (OSCC) reported yearly within Australia. Resection often leads to substantial defects, requiring complex reconstruction. The aim of this study was to examine how reconstruction at a dedicated head and neck cancer unit has evolved over a 30-year period. A retrospective review was conducted of all OSCC carcinoma cases performed from 1988 to 2017. Data was analysed in six-time periods; pre-1995, 1995–1999, 2000–2004, 2005–2009, 2010–2014, and 2015 and above. A total of 903 patients were identified, of which 56.1% (n = 507) underwent free flap reconstruction including 426 (84.0%) soft tissue free flaps (STFF) and 81 (16.0%) bony free flaps (BFF). STFF usage remained stable over time. The radial forearm was the most common free flap but declined over time with increasing use of the anterolateral thigh flap. The number of BFF increased from 5.0% before 1995 to 20.4% in 1995–2015. The tongue was the most common subsite, followed by the floor of mouth. Free flaps were utilised in more than 50% of OSCC reconstructions at each time period. Over time, the proportion of different STFF evolved towards increased use of the ALT flap and BFF within our institution. Level of evidence: Level four.

Time-domain electromagnetic simulations employing unstructured tetrahedral meshes can be sensitive to local mesh characteristics. In particular, the maximum permissible time step for stable operation can be unacceptably small. In this paper, a cell clustering technique is described for the transmission line modeling algorithm that reduces the sensitivity to local mesh characteristics and permits substantial increases in time step to be made without compromising accuracy or stability.

A novel triangular TLM node containing a subcell sized wire of arbitrary radius is presented. The technique is based upon the mapping between the total field at the cell boundary and exact modal field expansions around the wire. The wire node is incorporated into an unstructured 2D TLM algorithm providing a flexible package for modeling fine-features in proximity to complex structures. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1753–1757, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23482

Using a quantitatively calibrated imaging system and specially fabricated tapered lasers with windowed n-contacts, the authors image the spontaneous emission distribution inside two different laser cavities as a function of injection current. In the first device, an array of narrow-angle index-guided tapered lasers, significant thermal and electrical coupling between the emitters was observed. In the second device, a wide-angle gain-guided tapered laser, significant spatial hole burning was observed above threshold. The spontaneous emission distributions of this wide-angle device have been compared with simulation results from a 2.5D laser simulator and show good quantitative agreement in the quantum well carrier density.

This paper presents a transmission-line modeling (TLM) algorithm, which is based upon unstructured tetrahedral meshes. In comparison with the conventional, usually Cartesian, scheme, the use of such meshes provides a significant enhancement in the flexibility and accuracy of the TLM simulations, permitting both smooth boundary approximations and the use of diversely sized elements in multiscale problems. A full theoretical development of the unstructured algorithm is presented for the first time and canonical problems are used to demonstrate the computational advantages available. Particular consideration is given to practical meshing constraints and the merging of adjacent tetrahedra into larger cells used to avoid the use of undesirably small time steps.

To date, the transmission line modelling method has been applied to structured, usually Cartesian, meshes. The flexibility offered by using 2D and 3D unstructured meshes, which is invaluable for practical simulation tasks, is now combined with the transmission line modelling algorithm to yield a powerful tool for computational electromagnetics.

We study the influence of a patterned contact design on the beam properties of high-brightness tapered lasers. A simple approach to simulate patterned injection has been developed and introduced into a quasi-three-dimensional tapered laser model. The method is applied to tapered lasers, whose performance is limited by two different mechanisms: self-focusing and poor modal filtering. The results show an improvement in beam quality in comparison to standard devices.

Experimental measurements of the spatial distribution of the spontaneous emission produced inside the cavity of a 4° 980 nm tapered laser are presented and compared with the results of a 2.5 D half-space, hot-cavity simulation. A custom device with a windowed n-contact was designed and fabricated for this work. The effectiveness of this windowed contact was investigated and appears to be satisfactory. The measurement system for photo- and electroluminescence microscopy imaging was quantitatively calibrated with an error of < ±15%. Good agreement between the experimental and simulated results are presented, with an error of ~ 6% in the carrier density at the output facet.

Transmission-line modeling (TLM) is an established numerical simulation method for electromagnetics that has been employed in a wide variety of application areas. To date, TLM has been formulated primarily for structured (usually Cartesian) meshes. This paper presents and illustrates the application of a new TLM algorithm suitable for use with unstructured two-dimensional meshes based upon triangular elements.

We present a simulation tool useful to optimize the design of semiconductor tapered lasers and to study the physical processes inside of them. This is achieved by using a state-of-the-art quasi-three-dimensional (quasi-3-D) electrical and thermal model, coupled to a two-dimensional (2-D) wide-angle beam propagation method optical model. A calibration procedure of model parameters is proposed to contribute to the development of reliable simulation tools. Different laser diodes with a tapered gain section, emitting at 735 and 975 nm, are used to validate the model through the extensive comparison of experimental and simulated results. The suitability of 2-D and 3-D electrical, thermal, and optical models is discussed in terms accuracy and computational effort.

The properties of a tapered semiconductor laser cavity, which can be used to generate a high-brightness optical beam, are studied. The cavity consists of a narrow straight waveguide section and a tapered power amplifier section. The influence of the input waveguide width and length, as well as of the length and taper angle of the power amplifier section, on the overall performance of the cavity are discussed. Finally, the application of beam spoilers is studied. In order to solve the wave equation, the wide-angle-beam propagation method incorporating a higher-order finite-difference scheme is applied.

The nonlinear phenomena accompanying the process of light generation in high-power tapered semiconductor lasers are studied using a combination of simulation and experiment. Optical pumping, electrical overpumping, filamentation, and spatial hole burning are shown to be the key nonlinear phenomena influencing the operation of tapered lasers at high output powers. In the particular tapered laser studied, the optical pumping effect is found to have the largest impact on the output beam quality. The simulation model used in this study employs the wide-angle finite-difference beam propagation method for the analysis of the optical propagation within the cavity. Quasi-three-dimensional (3-D) thermal and electrical models are used for the calculation of the 3-D distributions of the temperature, electrons, holes, and electrical potential. The simulation results reproduce key features and the experimental trends.

Dietary texture has been reported to influence parasite establishment and survival, but to what degree this relationship is modified by either the type or quantity of dietary fibre is unknown. Using a 2×4 factorial design, we explored the relationship between fibre type (soluble = pectin vs insoluble = cellulose) and fibre quantity (0, 5, 10 and 20% by dry weight) on parasitic outcomes in BALB/c mice infected with 100 Heligmosomoides polygyrus (Nematoda) larvae. Pectin, but not cellulose, exerted a significant effect on parasite egg production. Following in vitro culture of female worms, increasing levels of dietary pectin were associated with increasing release of eggs. Yet this pattern was not observed in vivo, where per capita egg production peaked at the 10% pectin concentration, but was very low in mice fed 20% pectin. Parasite establishment was elevated in mice fed 20% pectin, but was unaffected by cellulose concentration. Neither type nor quantity of fibre affected H. polygyrus survival or spatial distribution along the gastrointestinal tract. To what degree differences in parasite establishment and reproduction could be attributed to the marked effects of pectin on gut morphology (increased intestinal length, villus length, mucosa thickness and villus/crypt ratio) requires further exploration. Our data indicate that cellulose is preferable to pectin as the source of fibre for experimental diets as cellulose did not affect H. polygyrus establishment, reproduction or survival during a 4-week primary infection.

In the Earth’s magnetosphere, electron–whistler mode wave–particle interactions are a candidate mechanism for auroral precipitation via electron phase space diffusion. Of particular interest are stochastic interactions between relativistic electrons and (as often observed) waves of more than one wave number. It can be shown that the interaction between electrons and two oppositely directed monochromatic whistlers is stochastic. Once a threshold is exceeded, stochastic trajectories exist in addition to regular orbits (Kolmogorov–Arnold–Moser, or KAM, surfaces) near resonance, and here their corresponding pitch angle diffusion is estimated. The treatment is extended to consider broad band whistler wave packets and it is shown that the stochastic diffusion mechanism is again present for interactions with one or two wave packets. The pitch angle diffusion coefficient is estimated from the dynamics of stochastic electrons. For wave amplitudes consistent with planetary magnetospheres, such as at the Earth and J...

Using numerical solutions of single-particle dynamics, we consider a chaotic electron–whistler interaction mechanism for enhanced diffusion in phase space. This process, when applied to parameters consistent with the Jovian magnetosphere, is a candidate mechanism for pitch angle scattering in the Io torus, thus providing a source of auroral precipitating electrons. We initially consider the interaction between two oppositely directed monochromatic whistler mode waves. We generalize previous work to include relativistic effects. The full relativistic Lorentz equations are solved numerically to permit application to a more extensive parameter space. We use this simplified case to study the underlying behaviour of the system. For large-amplitude monochromatic waves the system is stochastic, with strong diffusion in phase space. We extend this treatment to consider two oppositely directed, broad band whistler wave packets. Using Voyager 1 data to give an estimate of the whistler wave amplitude at the Io torus at Jupiter, we calculate the degree of pitch angle scattering as a function of electron energy and initial pitch angle. We show that for relatively wide wave packets, significant pitch angle diffusion occurs (up to ±25°), on millisecond timescales, for electrons with energies from a few keV up to a few hundred keV.

Micro-resonators are critical optical components that have many exciting applications in fields such as telecommunications, quantum cryptography and optical signal processing. Fabrication techniques allow many different designs of micro-resonator to be realised, but at present their optimisation and simulation remain firmly entrenched in 2D. The geometrical complexity of many micro-resonators mitigates against analytic study. Thus there is a strong demand for comprehensive 3D numerical simulations. We discuss some of the difficulties and challenges when modelling micro-resonators and recent progress towards their 3D modelling using time-domain codes.

Flexible simulation solvers are paramount for the development of a wide range of modern technologies. Numerical techniques complement computationally efficient analytical approaches and offer ease of use and applicability to a wide range of applications. The Transmission Line Modeling Method has recently been extended to the domain of tetrahedral mesh descriptions of structure geometry and this presentation discusses a number of recent advances that affect its practical deployment.

A novel triangular TLM node containing a sub-cell sized wire of arbitrary radius for incorporation into an unstructured 2D TLM algorithm is presented. The wire-node formulation is based upon the mapping between the total field at the cell boundary and exact modal field expansions around the wire. The integration of the wire node into an unstructured 2D TLM algorithm provides a flexible package for modelling fine-features in proximity to complex structures.

The paper describes recent advances in the treatment of multi-scale problems and complexity in the electromagnetic simulation of complex systems.

SUMMARYThis study determined whether the timing of re-feeding of protein-deficient mice restored functional protection against the gastrointestinal nematode,Heligmosomoides bakeri. Balb/c mice were fed a 3% protein-deficient (PD) diet and then transferred to 24% protein-sufficient (PS) diet either on the day of primary infection, 10 days after the primary infection, on the day of challenge infection, or 7 days after the challenge infection. Control mice were fed either the PD or PS diet. Onset of challenge, but not primary, infection caused short-term body weight loss, anorexia and reduced feed efficiency. Weight gain was delayed in mice when re-feeding commenced on the day of challenge infection; alkaline phosphatase (ALP) was also elevated in these mice on day 28 post-challenge. In contrast, other re-feeding groups attained similar body weights to PS mice within 4 days and had similar ALP at day 28. Serum leptin was higher in PD than PS mice and positively associated with food intake. As expected, worm survival was prolonged in mice fed the PD diet. However, egg production and worm burdens were similar in all re-feeding groups to the PS mice, indicating that protein re-feeding during either the primary or challenge infection rapidly restored normal parasite clearance.

Beam spoilers are an integral part of high-power laser diode design, being used to provide improved output beam quality by spatially filtering higher order field components from the backward travelling wave. They consist of deeply etched angled trenches and this inherent three-dimensional nature is one reason why, despite their practical importance, no systematic design of beam spoilers has been undertaken. In this paper we compare and contrast simulation methods for this purpose, including beam propagation and TLM methods.

Current technology trends require the utilisation of very high clock rates which have a broad electromagnetic spectrum. Electronic equipment designers require accurate characterisation and optimisation of electrical components, sub-systems and complete systems at frequencies that extend well into the microwave spectrum. This paper aims to assess the state-of-the-art in full field solvers in system and sub-system design and in doing so identify the trends in simulation techniques that are targeted towards the development of complex designs which operate at high speeds. Particular emphasis is placed on the treatment of multiscale problems, the development of macronodes containing sub-wavelength features and optimal meshing techniques. Developments in these areas are illustrated with results typical of EMC and SI design issues

Transmission Line modeling is a time domain simulation method suitable for integrated optics. Structured Cartesian or nonorthogonal formulations require fine meshes to avoid staircasing. Application of unstructured and frequency domain implementations for optoelectronics are discussed.

We have developed Al-free broad area lasers with low optical losses of 0.5 cm-1 and T0 = 171 K. Clarinet lasers deliver 0.65 W cw with an M2 of less than 1.3 at 1/e2. (2 pages)

Numerical simulations of gain guided tapered lasers have been applied to achieve a physical insight into the beam quality limitation mechanisms and to provide guidelines to optimise the device design. The analysis is based on a numerical model which has demonstrated an excellent agreement with experiments for different geometries and lasing wavelengths, providing useful insight on the internal processes.

Much present day simulation and design for optoelectronics involves approximations due to the limitations of today's computer resources. For example, finite difference beam propagation (FD-BPM) methods assume that the propagation takes the form of an envelope function multiplied by a propagation factor. These approximations can limit the utility of present methods. The next generation of software must aim to eliminate these limitations, ideally correctly solving the vector Helmholtz equation subject to open boundary conditions. In this paper we will address how advances in our understanding, novel approaches and computer power are moving us towards this goal.

In this work we use a numerical model to analyze the beam filamentation in tapered lasers with the goal of optimizing the epitaxial structure. The model self-consistently solves the steady state electrical and optical equations for the flared unstable resonator. This model has been applied to simulate the performance of InGaAs/InGaAsP tapered lasers emitting at 975 nm. We investigate the role of the active material properties (carrier induced index change, differential gain) and of the epitaxial design (optical confinement factor) on the filamentation process and on the maximum achievable power.

High performance fibre EDFA amplifiers for dense WDM systems require efficient and economic pumping devices. One way of providing high pumping power to an EDFA amplifier at low cost is to use tapered semiconductor lasers. The development of a software package for the design and optimisation of these high power tapered laser diodes is described. Cold cavity modelling enables the influence of the laser geometry on the overall performance of the cavity to be investigated along with the beam spoiler design. A 2.5D hot cavity laser model also takes into account effects such as spatial hole burning, carrier diffusion and current spreading. This enables detailed investigation of the laser design and the factors limiting beam quality to be carried out. Our present research aims to incorporate a 3D model of the optical propagation into the laser model using wide-angle FD-BPM schemes, novel finite difference techniques, and modem matrix solvers to minimize memory usage and calculation time.

The properties of a tapered semiconductor laser cavity utilised for the generation of a high power, good quality optical beam are investigated. In particular the influence of the straight section width and length as well as the angle and length of the tapered section on the overall performance of the cavity are studied. In order to solve the wave equation, the wide angle beam propagation method has been applied. The computer memory requirements are relaxed by the use of higher order finite difference schemes.

A quasi-3D model has been developed with the aim of studying the different factors limiting the performance of high-brightness high-power tapered lasers. The model solves the complete semiconductor and thermal equations, neglecting the flow of carriers and heat along the cavity ax is, together with a 2D Wide-Angle Beam Propagation method solving the optical propagation. The coupling between electrical, thermal and optical equations yields a stable solution which incorporates carrier and temperature induced perturbations of the refractive index. Although tapered lasers have already demonstrated superior beam quality performance in comparison with broad area devices, they still suffer of beam filamentation at high power levels. We analyze the influence of the different competing factors in the self-focusing process for 980 nm lasers with a gain guided taper section. The simulation results indicate that the lasers with the longest taper section provide the highest output power before the filamentation process is triggered, and that the backward propagating field plays a crucial role in the stability of the output beam.

An investigation into the convergence behaviour of two separate schemes for coupling the electromagnetic and electronic models in the simulation of a semiconductor laser is presented. One model couples the optical and electronic models once per optical round trip (separate solution model - SSM), whereas the other couples the optical and electronic models at each optical step along the cavity (coupled solution method - CSM). Results are presented using a simple 1D model to show that the CSM provides better numerical stability and faster convergence. Results are also presented from a more complex coupled laser model, based on a quasi-3D solution, which demonstrate that the CSM is capable of rapid convergence.

To compare endogenous cholesterol biosynthesis measured by deuterium incorporation (DI) and mass isotopomer distribution analysis (MIDA), cholesterol fractional and absolute synthetic rates were measured simultaneously by both techniques under identical physiological conditions. Twelve subjects (22 to 39 years of age) underwent a dual stable isotope protocol, involving oral deuterium oxide administration and measurement of incorporation of deuterium into cholesterol coincident with constant infusion of sodium [1-(13)C]acetate and measurement of the mass isotopomer distribution pattern of newly synthesized cholesterol. Synthesis was determined over 24 h with a 7-h feeding period. Both methods yielded similar measurements of fractional cholesterol synthesis (7.8 +/- 2.5% day(-)(1) for DI vs. 6.9 +/- 2.2% day(-)(1) for MIDA). Correlation of fractional synthesis across techniques was strong (r = 0.84, P = 0.0007). Absolute synthesis rates were also not different at 24 h (13.4 +/- 4.3 mg kg(-)(1) day(-)(1) for DI vs. 11.9 +/- 3.6 mg kg(-)(1) day(-)(1) for MIDA, r = 0.79, P0.002). We conclude that despite different assumptions and analytical requirements, deuterium incorporation and MIDA yield similar rates of cholesterogenesis in humans when measurements are made over 24 h. The decision as to which method to adopt depends on available clinical and analytical facilities

Infant pigs (8.5 kg) were fasted for 16 h and infused for 6 h with [U-13C]glucose. The fractional abundances of all13C mass isotopomers of plasma glucose, lactate, and pyruvate and of plasma, hepatic, and very low density lipoprotein apolipoprotein B-100 (apoB-100) alanine, glutamate, and aspartate were measured. The ratios of [13C3]aspartate, [13C3]glutamate, and [13C3]alanine in apoB-100 were used to estimate the positional equilibrium of [13C3]oxaloacetate, the fractional contribution of pyruvate carboxylase to the hepatic oxaloacetate flux, and the activity of hepatic pyruvate dehydrogenase. The values were compared with those based on glucose labeling and previously published equations. The two methods [Katz and Lee method (J. Katz, P. A. Wals., and W.-N. P. Lee. J. Biol. Chem. 264: 12994–13001, 1989) and apoB method] gave similar estimates of the positional equilibrium of [13C3]oxaloacetate (0.59, Katz and Lee method; 0.61, apoB method) but slightly different estimates of the contribution of pyruvate carboxylase to the oxaloacetate flux (0.36, Katz and Lee; 0.31 apoB). Gluconeogenesis apparently contributed between 71 (Katz and Lee method) and 80% (apoB method) of the glucose entry rate (25 μmol ⋅ kg−1⋅ min−1), and pyruvate dehydrogenase contributed 20% of the hepatic acetyl-CoA. We conclude that the labeling of aspartate in apoB-100 provides a good estimate of the isotopomer distribution in hepatic oxaloacetate but may underestimate the absolute isotopic enrichment by 50%.

The classical definition of essential amino acids is those α-amino acids whose carbon skeleton cannot be synthesized in the human (animal) body (1). Over the past 15 years it has become apparent that the simple division of 20 amino acids for which there exists a t-RNA into essential and non-essential was too simplistic (2). A newer terminology has been created, which will be used in the remainder of this review, namely, indispensable (which is equivalent to essential), conditionally indispensable and dispensable (which is equivalent to non-essential). The concept of conditionally indispensable is particularly important when considering the amino acid needs of infants. Optimal growth of lean tissue requires that an appropriate mixture of all 20 amino acids and sufficient non-protein energy is present to optimize net protein synthesis. Interestingly, Duffy et al. (3) in parenterally fed very low birth weight neonates and Fuller (4) in piglets have shown that an improved balance of amino acid intake results in enhanced net protein deposition by reducing endogenous protein breakdown.

The requirements for the indispensable amino acids have been determined by a number of different methods. Historically, descriptive or gross measures like growth and nitrogen balance have been used. However, technological advancements in recent years have resulted in the use of more precise and mechanistic metabolic approaches (i.e., plasma amino acid concentrations, amino acid oxidation, indicator amino acid oxidation) to examine requirement. Nevertheless, the current recommendations are still based on nitrogen balance studies. Requirement estimates based on other methodologies, such as plasma amino acid concentrations and direct amino acid oxidation, suggest that the requirement estimates derived from nitrogen balance experiments are too low. However, these higher estimates have also been criticized on conceptual and methodological grounds, resulting in considerable controversy in the area of indispensable amino acid requirements. A new technique, indicator amino acid oxidation, addresses many of the criticisms directed toward the alternative methods and the proposed higher requirement estimates. This paper reviews the current knowledge of amino acid requirements and makes recommendations in light of new information that has been provided from recent indicator amino acid oxidation research. It is concluded that the nitrogen balance-based estimates of amino acid requirement are too low.

The validity of measuring isotopic enrichment of amino acids in urine was tested in neonates during different feeding regimens and tracer administration protocols, and with different amino acid tracers. Twenty infants, fed enterally or parenterally, were given primed, constant infusions of 15N-glycine, L-[1-13C]leucine, and L-[1-13C]phenylalanine. Urine was collected every 2 h for 16 h. Blood was sampled only when required clinically. At baseline, enrichment in plasma and urine did not differ for any amino acid. At isotopic steady state, leucine enrichment was similar in plasma and urine, while the agreement was slightly weaker for glycine and phenylalanine, probably because of problems inherent in drawing blood samples from neonates. Study protocol did not affect the agreement. Since urine collection involves minimal invasive procedures, this approach could facilitate more indepth tracer studies in infants and children.

High-power and high-brightness continuous-wave (cw) operation has been achieved with an optimized design of fully index-guided tapered laser emitting at 975 nm. The device achieves simultaneously negligible astigmatism and stable low divergence in the lateral axis at high-power operation. By using a quasi-three-dimensional simulation model, the different mechanisms modifying the slow axis beam divergence at high power have been carefully balanced in the clarinet design, easing the use of collective optics in laser bars. The devices consist of a relatively long ridge-waveguide filtering section coupled to a relatively short tapered section with an aperture angle of 2°. InGaAs∕InGaAsP lasers were fabricated with this design, demonstrating an output power of 1 W cw, a maximum wall-plug efficiency of 50%, negligible astigmatism, a slow-axis far-field divergence (measured at 1∕e2) of 5° at 1 W and beam quality parameter M2

An elegant and accurate technique of interfacing segments of a uniform computational mesh with different spatial resolution is described. The technique is illustrated in the time-domain for a TLM mesh. Results show that a seamless interface is achieved between different mesh areas, thus allowing multi-scale problems to be accurately mapped onto the mesh.

CHARACTERIZATION OF PATHWAYS OF ENDOGENOUS SYNTHESIS OF LONG CHAIN POLYUNSATURATED (LC-PUFA) FATTY ACIDS IN PIGLETS. ▴ 1903

The enzyme-reduced coenzyme-alpha-ketoglutarate ternary complex is a critical intermediate in the glutamate dehydrogenase-catalyzed reaction. Oxalylglycine, a structural analog of alpha-ketoglutarate which contains an amide carbonyl group in place of a reducible ketone group, is one of the few compounds known to complete with alpha-ketoglutarate itself. In order to examine the role of the ketone group of alpha-ketoglutarate in the ternary complex, we have carried out a calorimetric study of the corresponding oxalylglycine ternary complex, determining the complete delta H, delta G, delta S, and delta Cp profiles and the corresponding interaction parameters for that complex and have compared the various parameters with the corresponding ones previously reported for the alpha-ketoglutarate ternary complex. While the overall delta G values of the two ternary complexes differ only slightly, the enzyme-NADPH-oxalylglycine ternary complex appears to achieve much of its stability from a very tight enzyme-oxalylglycine binary complex with little or no contribution from favorable interactions in the ternary complex, while the alpha-ketoglutarate ternary complex appears to achieve the same stability by a large interaction starting from a very weak enzyme-alpha-ketoglutarate binary complex. Consideration of the enthalpic profiles, however, show that this delta G-derived picture is deceptive. The excess binding energy which stabilizes the oxalylglycine binary is in fact due to hydrogen bonding of the amide group of oxalylglycine to the enzyme; in forming the ternary complex, this hydrogen bonding is lost in favor of forming an oxalylglycine-NADPH interaction, which is very similar to the alpha-ketoglutarate-NADPH interaction which stabilizes the alpha-ketoglutarate ternary complex. We conclude that the alpha-ketoglutarate-NADPH interaction must depend on either hydrogen bonding to or steric hindrance by the ketone group and that the existence of this energetically large interaction cannot be ascribed to imine formation between the keto group and enzyme. These findings also indicate the locus on the reaction coordinate where the reduced coenzyme plays a critical role, a role other than its obvious function as a hydride donor.

The Red-necked Stint Calidris ruficollis breeds in the northern hemisphere and migrates to southern latitudes for its non-breeding period where adults undergo a complete moult of the flight feathers. Juveniles follow the adults to the wintering grounds but remain for the breeding season, the southern winter, and do not moult all their flight feathers until the following year. Returning adults and second-year birds begin to moult their primaries between late August and early December and finish between late December and late March. The mean duration of moult of their primaries is calculated as 130 days, fifteen days longer than that previously reported. Previous authors may not have distinguished non-moulting first-year birds and the inaccuracies in their method of calculation probably account for the difference. Distributions of the moult scores of the primaries of the adults are unimodal and we dispel Evans's (1975) suggestion of subgroups. Pooling of data from separate samples, asymmetry between the wings during early stages of moult, decrease in the rate d moult in middle to late stages and possible bias in sampling all may have contributed to the artificial formation of subgroups.

An optical method of detecting electron polarization which measures the polarization at any desired angle to the electron momentum with equal efficiency is proposed. The method requires no calibration and is intermediate in efficiency between low and high energy Mott detection.