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Introduction The aim of this study was to determine whether ultrasound alone is sufficient to safely exclude malignancy in thyroid nodules in a district general hospital setting, to comply with the latest British Thyroid Association guidelines. Methods This retrospective study investigated the quality of ultrasound reporting and the correlation between ultrasound report and histology for individual thyroid nodules. Cases were selected from the thyroid multidisciplinary meeting and included all patients having undergone surgery for a thyroid malignancy in a one-year period. Results Forty-seven patients were included in the study. Ultrasound reports were reviewed and assessed, in which 21 clinicians were involved; 36% of scans included a summary of whether the nodule(s) overall appeared benign, equivocal, suspicious or malignant; 4% of reports included a U classification; 81% of reports commented on cervical lymph nodes. Ultrasound was compared with histology. The sensitivity of ultrasound in correctly identifying nodules requiring further investigation was of 56% and specificity was 81%. Positive predictive value was 81% and negative predictive value was 56%. Discussion These findings suggest that, in a district general hospital setting without a dedicated head and neck radiologist, using only ultrasound and limiting fine-needle aspiration cytology to identify suspicious nodules may not be safe, as a high number of nodules appearing benign on ultrasound may ultimately prove to be malignant.

A review of high operating temperature (HOT) infrared (IR) photon detector technology vis-a-vis material requirements, device design and state of the art achieved is presented in this article. The HOT photon detector concept offers the promise of operation at temperatures above 120 K to near room temperature. Advantages are reduction in system size, weight, cost and increase in system reliability. A theoretical study of the thermal generation-recombination (g-r) processes such as Auger and defect related Shockley Read Hall (SRH) recombination responsible for increasing dark current in HgCdTe detectors is presented. Results of theoretical analysis are used to evaluate performance of long wavelength (LW) and mid wavelength (MW) IR detectors at high operating temperatures. (C) 2013 Elsevier B.V. All rights reserved.

We present a method of analyzing the non-uniformity in electrical characteristics of HgCdTe photodiode arrays for infrared imaging applications. We have selected dynamic resistance–voltage (R–V) characteristics for analyzing electrical behavior of HgCdTe photodiodes because the dynamic resistance at a given operating voltage directly governs the imager performance and being derivative of current–voltage (I–V) characteristics, it has little impact of the constant shifts due to stray illumination during dark measurements, relaxing the stringent requirement of perfect dark conditions to some extent for performance analysis. We have demonstrated that by using statistical analysis such as correlation of the selected signatures and their principal component analysis, we can identify the root cause of the high non-uniformity among sensor pixels in the array. The method has been implemented using theoretical I–V model of MWIR HgCdTe photodiodes, but it is generic and may be implemented on any other types of diode arrays for theoretical or experimental analysis of their non-uniformity.

Micro-Raman spectroscopy was used to evaluate the surface quality of Hg 1− x Cd x Te ( x = 0.3) epitaxial layers polished with chemo-mechanical and free chemical etching processes. Raman technique has been employed to monitor the HgCdTe detector array fabrication process to ensure epilayer surface devoid of impurities and minimal damage. Chemical etching with bromine–methanol solution is seen to leave residual damage or non-stoichiometric HgCdTe surface layer indicated by an asymmetrical broadening and down shift in all Raman peaks. A peak at 112 cm −1 as defect mode or due to disordering on the epilayer surface has been noticed.

In this paper, the ranges of two specific long-wave infrared (LWIR) and mid-wave infrared (MWIR) focal plane array (FPA) systems are estimated and compared, using MODTRAN to calculate atmospheric transmission and NVTherm to calculate the ranges. The calculations are for a standard tank target, clear weather conditions and a horizontal terrestrial path at mean sea level, under varying ambient temperature and relative humidity (RH) conditions. Detection ranges are more sensitive to temperature and RH variations than the recognition ranges, while identification ranges are the least sensitive. LWIR ranges depend more upon these variations than do MWIR ranges. The relative range ratios are plotted versus the ambient temperature and RH as a contour plot. Typically, LWIR systems perform better at lower ambient temperatures and RHs, while MWIR systems are advantageous at higher temperatures and RHs. The so-called ‘phase curve’ separating the MWIR and LWIR ‘phases’ also depends upon system parameters (FPA and optics). Ambient temperatures and RHs vary diurnally and seasonally, and over kilometer distance scales. Our proposed plot is more flexible than the standard scenarios used in MODTRAN. The advent of dual band imaging systems has not rendered this discussion irrelevant since the more producible FPAs are sequential rather than simultaneous.

We propose a unified approximate analytical expression for the carrier density of HgCdTe semiconductors that have non-parabolic energy bands and are highly degenerate. The proposed expression is without any adjustable parameter. It can be applied to HgCdTe for the case where electron densities are very high and the material is strongly degenerate, e.g., a highly accumulated surface due to passivant-induced negative fixed charge density in an n-HgCdTe photoconductor device. The proposed expression is simultaneously valid for SWIR, MWIR and LWIR bands.

A compositionally graded surface layer has been created for the passivation of Hg1-xCdxTe photodiodes. The graded CdTe-Hg1-xCdxTe interface was created by deposition of CdTe and subsequent annealing. It was found that the composition gradient and width of the graded region could be tailored by adopting a suitable annealing procedure. The effect of grading on the interface electrical properties and photoelectrical properties was studied by X-ray photoelectron spectroscopy (XPS), photoconductive decay, and C-V measurements. Insulator fixed-charge density and interface-trap density could be reduced to 3times1010 cm -2 and 2times1010 cm-2middoteV-1, respectively, by creating a graded interfacial composition. The interface conditions so engineered led to a low surface recombination velocity ~3000 cm/s. A direct correlation has been established between the process conditions, interfacial composition, and the electrical/photoelectrical properties of the CdTe-Hg1-xCdxTe heterostructures. The passivation layer formed by this method is shown to be suitable for the fabrication of high-performance infrared detectors

A compositionally graded CdTe-Hg1−xCdxTe interface was created by deposition of CdTe on p-HgCdTe and subsequent annealing. The compositionally graded layer between CdTe and HgCdTe was formed by an interdiffusion process and was used for passivation. The composition gradient (Δx) in the interfacial region and the width of the graded region were tailored by adopting a suitable annealing procedure. The effect of process conditions on the interfacial profile and photoelectric properties such as lifetime and surface recombination velocity was studied in detail. Surface recombination velocity of the p-HgCdTe could be reduced to the level of 3,000 cm/s at 77 K, which represents very good passivation characteristics. The passivation layer formed by this method can be used for the fabrication of high performance and stable modern infrared detectors. Thus, a passivation process is developed, which is simple, effective, reproducible, and compatible with the HgCdTe device fabrication and packaging processes.

Summary Background Treatment with a continuous i.v. proton pump inhibitor is presumed to promote clot formation and stability by sustaining intragastric pH ≥ 6. Aim We postulated that very frequent oral dosing of proton pump inhibitors should simulate i.v. infusion and achieve similar pH control. Methods Twenty healthy volunteers were stratified by Helicobacter pylori status (10 positive; 10 negative) and had determination of CYP2C19 status. After an overnight fast, an intragastric pH probe was placed. Subjects received 120 mg of lansoprazole at 8 am and 30 mg every 3 h until 8 pm. Intragastric pH was measured over 24 h, and lansoprazole plasma concentrations were determined at five time points. Results Intragastric pH was ≥6 for 41% (95% CI: 30–53%) of the 15-h period from 8 am–11 pm and 46% (95% CI: 35–56%) of the 24-h period (8–8 am). The mean proportion of patients with pH ≥6 was not significantly different in H. pylori-positive vs. negative patients. Only 25% of subjects sustained pH ≥6 for at least 60% of the 15-h period, and 35% had a sustained pH ≥6 for at least 60% of the 24-h period. Conclusions A dose of 120 mg of oral lansoprazole followed by standard 30 mg doses of lansoprazole every 3 h did not reliably sustain pH at the desired level of 6.

We present the results of calculations for surface shunt resistance due to the passivant fixed charge density (Qss) in n-HgCdTe photoconductive (PC) detectors. To the best of our knowledge, this is the first detailed calculation involving the actual majority carrier profile at the accumulated surface. The effect of surface field (or potential) due to heavily accumulated density of majority carriers on surface mobility (μs) has been investigated in detail by employing the Schrieffer and Goldstein models using random diffuse scattering. Additionally, the effect of lateral field (applied to these devices) on surface mobility is included by invoking the model of Yoo et al. The above effects were not taken into account in previous simplified models. For narrow-band, n-type HgCdTe the effects of carrier degeneracy and band non-parabolicity cannot be neglected. In this work, a one-dimensional model including these effects has been developed to evaluate the detector resistance and responsivity. A proper two-layer (bulk and surface) responsivity model is developed. The results are compared with the widely-used approximate one-layer model of Reine and with the step model proposed by Bhan and Gopal. It is shown that, for the Reine model, the agreement with the present model depends on the value of μs chosen. The trend of the step model agrees with the Reine model, but both models show disagreement with the present one-layer and two-layer profile models for Qss ≈ (1010–1012) cm−2.

The dependence of the zero-bias resistance-area (RA) product and the quantum efficiency (η) of variable-area diode arrays is numerically calculated by solving the diffusion equation in a cylindrical, three-dimensional geometry in the thick base approximation. The calculation is done for long-wavelength IR HgCdTe n+-on-p diffusion-limited photodiodes at 77 K. The inverse resistance-area product 1/(RA) and the square root of the quantum efficiency, η1/2, are plotted against the perimeter-to-area (P/A) ratio. The 1/RA results are fitted to a quadratic dependence on the P/A ratio. The dependence of the 1/RA on the minority carrier diffusion length, the junction depth and the surface recombination velocity (SRV) is evaluated. An empirical expression is proposed that largely accounts for the dependence of the coefficients of the quadratic on these parameters and is more general than those used in previous studies. The results are also in reasonable agreement with the results of Briggs, expressed in terms of the parameter f3D, that are valid for zero junction depth and zero SRV. The slope of the quantum efficiency versus P/A plot, which is approximately a straight line, is related to an effective length Lopt, that also depends on the diffusion length, junction depth, SRV and the absorption coefficient α. The parameter Lopt varies as α1/2.

In this paper, the varying composition (x) of the Hg1-xCdxTe epilayer is related to a new parameter namely the shift in the forward bias voltage at a constant current (Vcon) of the photovoltaic (PV) diodes in an array environment. The dependence of Vcon on the composition x is investigated both theoretically and experimentally. It is shown that Vcon is almost linearly proportional to x and hence can be utilized as a calibration standard for mapping x or non-uniformity in x. Here, this is done by fabricating nine 16×16 photovoltaic diode arrays on liquid-phase epitaxy-grown mercury cadmium telluride, Hg1-xCdxTe, of nominal composition x = 0.227. The composition x or cut-off wavelengths (λc) determined from Fourier transform infrared transmission for three specific PV diodes having different compositions (x) are correlated with the shift in Vcon of current-voltage (I-V) characteristics of these diodes. Following this, Vcon versus x is plotted which is used as a calibration curve for mapping non-uniformity in x in terms of Vcon for a given technology. Furthermore, it is proposed that, in addition to the usual information, the I-V characteristics can be used to monitor any process-induced changes in the composition of the starting material.

In this paper a model for calculating the quantum efficiency and the specific detectivity of both and photodiodes, considering both front- and backside illuminated configurations, is presented. The diode is analysed by assuming a step model for the concentration profile. The effects of the surface recombination velocities at different surfaces/interfaces of the diode, the minority carrier lifetimes and the carrier concentrations are considered. It is pointed out that the parameter to be optimized for a photodiode is and not the zero-bias resistance - area product , although the latter combines with the quantum efficiency to determine the behaviour of . Based on our calculations, it is observed that the values of different parameters that maximize are different from those that are optimal for high quantum efficiency. For sufficiently high , dominates ; otherwise, both factors affect . The calculation of done here refers to the long-wavelength IR region where often is low, with the result that the injection efficiency into the CCD multiplexer is decreased, which has been taken into account.

The results of a quasi-two-dimensional model for calculating passivant-induced surface leakage currents due to band-to-band tunnelling in mercury cadmium telluride (MCT) photovoltaic (PV) diodes are presented. The object is to assess the effect of a fixed surface state charge density due to a passivant on the zero-bias resistance - area product for the technologically important case when surface state charges accumulate the MCT surface. Calculations are carried out to estimate the tolerable value of beyond which the of the MCT diode degrades. To the best of our knowledge, this is the first time that such a detailed calculation involving the acceptor concentration profile near the surface has been reported for long-wavelength IR (LWIR) MCT photodiodes. This calculation has been done numerically, and hence the depletion width (pinched near the surface), the electric field and the band-to-band tunnelling are calculated as a function of depth, layer by layer, from the passivant - semiconductor interface. The currents - diffusion, generation - recombination, band-to-band and trap-assisted tunnelling - have been calculated in each layer, and the zero-bias resistance - area product is determined for each mechanism. Hence, the resultant is calculated. The results are compared with the earlier step model of Bhan and Gopal (Semicond. Sci. Technol. 9 (1994) 289), which assumed a surface layer of constant concentration . The present model indicates that for photodiodes with a cut-off wavelength of and an acceptor concentration , operating at 77 K, a would degrade significantly. This value is insensitive to composition (in the LWIR). For an diode, the tolerable value of is found to depend on the concentration in the layer. Further, the tolerable value of for an diode is much higher than for an diode, for donor concentrations .

The effect of the layer in a structure made in long-wavelength (x = 0.229) epilayers on the zero-bias resistance - area product is theoretically analysed, and compared with a structure. A step profile is assumed for the concentration in the and layers, fabricated by ion implantation and annealing. Various current components (diffusion currents in the , and p layers, depletion layer and surface generation - recombination (g - r) currents, band-to-band and trap-assisted tunnelling) are taken into account. The effect of the surface recombination velocities, and the concentrations (p-side trap, layer, and p layer) are discussed in detail. The results of this model clearly indicate the conditions under which a diode can perform better than a diode. In broad terms, a structure is more suitable for p-type epilayers with lower trap concentrations and higher lifetimes, whereas a structure is advantageous, in terms of increasing , for higher trap concentrations and lower lifetimes. Another advantage of the structure is that reduced tunnelling implies that a higher acceptor concentration can be accepted for device fabrication.

Objectives:Airway fires pose a risk during laser microlaryngoscopy, and neurosurgical cotton patties, used to prevent tissue injury from stray laser beams, are a potential ignition source. Using a configuration approximating clinical practice, we experimentally assessed the relative impact of changing different ‘fire triad’ components on the occurrence of airway fires, in order to better inform patient care.Methods:The relative effects of wet vs dry neurosurgical patties, oxygen concentration and laser power setting on the patty ignition time were studied in a cadaveric porcine model. Data were analysed using t-test and two-way analysis of variance.Results:Dry patties ignited after 2.3 ± 1.2 seconds (average ± standard deviation) of continuous 5 W laser fire at 50 per cent oxygen concentration, compared with 63.9 ± 27.8 seconds for wet patties under the same laser and oxygen settings (p p Conclusion:We suggest that surgical patties should always be soaked and should be used for relatively short periods, in order to prevent drying. If at all possible clinically, prolonged laser use at high power settings and ventilation with 100 per cent oxygen should be avoided.

The authors report the first model of Zener tunnelling capacitance and its effect on the C-V characteristics of Hg1-xCdxTe. For narrow band Hg1-xCdxTe, with x=0.2, even at moderate doping densities, C-V curves exhibit low-frequency behaviour at measurement frequencies as high as 1 MHz (both for p-type and n-type MCT). The model predicts the reported trends in C-V characteristics as a function of composition, doping density and measurement frequency.

Background Infections caused by community-acquired, methicillin-resistant strains of Staphylococcus aureus (CA-MRSA) have become a major problem in children and adults. We recently reported that either of two clinical CA-MRSA isolates exposed to daptomycin (vs vancomycin) stimulated less macrophage tumor necrosis factor (TNF) secretion. We hypothesized that this difference might result from reduced release of bacterial products (such as bacterial DNA) from CA-MRSA isolates exposed to daptomycin (versus vancomycin). Purpose We sought to determine whether bacterial DNA contributed to the up-regulation of macrophage TNF production in response to a live CA-MRSA isolate exposed to vancomycin, daptomycin, clindamycin, or linezolid. Methods RAW 264.7 murine macrophages were stimulated for 16 to 18 hours with 107 cfu/mL of a well-characterized CA-MRSA isolate (USA300) in the presence of either vancomycin (20 mg/L), daptomycin (20 mg/L), clindamycin (20 mg/L), or linezolid (10 mg/L). In parallel, cells were preincubated for 1 hour prior to bacterial challenge with chloroquine (2.5 mg/L), a selective inhibitor of the bacterial DNA/Toll-like receptor 9 (TLR9) pathway. After stimulation, cell supernatants were collected and assayed for TNF concentration by ELISA. Results As we have previously reported, macrophages exposed to the CA-MRSA isolate in the presence of daptomycin (vs vancomycin) secreted significantly less TNF; clindamycin and linezolid were intermediate. Interestingly, preincubation of RAW cells with chloroquine led to substantial decreases in TNF secretion in response to the CA-MRSA isolate exposed to any of the four antibiotics. Furthermore, the magnitude of inhibition was consistently greater (70% vs 20-30%) in cells exposed to the SA isolate in the presence of daptomycin (compared with vancomycin, linezolid, or clindamycin). Conclusions Our data suggest that bacterial DNA plays an important role in the stimulation of TNF secretion by macrophages exposed to this virulent USA300 CA-MRSA isolate in the presence of any of the four antibiotics tested. Additional studies are needed to define the importance of bacterial DNA in stimulating the inflammatory response to staphylococcal infections.

Group A beta-hemolytic Streptococcus (GAHS) was isolated from 18% of swabs submitted to a district microbiology laboratory from girls with vulvovaginitis, a figure similar to that from a contemporary British study. This suggests that vulvovaginitis is more commonly associated with GAHS than reported previously. This could represent either an increase in frequency of the condition or better recognition of it.

There have been a large number of studies of infrared diode arrays, both experimental and theoretical, in which the trend has been toward increasing diffusion length in the devices.

The performance of an IR detector in an area array is studied by numerically solving the 2-D diffusion equation for thermal and photo- generated carriers. The zero-bias resistance area product R0A, quan- tum efficiencyh, and the noise equivalent temperature difference NETD for diodes of different size and junction depth are calculated for long wavelength infrared (LWIR) HgCdTe n 1 -on-p diffusion-limited diodes in the backside illuminated configuration. The 2-D calculations incorporate thermally generated- and photocarriers that originate under the junction (the ''normal'' current), as well as those that originate from around the junction (the lateral current). The calculation of the diffusion currents— both optical and thermally generated carriers—is made using a trapezoi- dal grid, which better fits the symmetry of diodes in an area array. The present results are compared with previous calculations in which a uni- form grid was used. The results of R0A and h calculated by the uniform and trapezoidal grids differ significantly, especially for diodes with deep junctions or diodes that are small compared to the center-to-center dis- tance between diodes. Both the uniform and trapezoidal grid calculations have been compared with spot scan measurements and Semicad simu- lation in a stripe diode array in the literature. © 2001 Society of Photo-Optical

The quantum efficiency and the crosstalk of a photodiode in a long wavelength IR (LWIR) 2-D diode array are studied by numerically solving the 2-D diffusion equation of photocarriers in an array environ- ment. The quantum efficiency depends strongly on both the diode size and the junction depth, and can be expressed, to good accuracy, as a quadratic function of the two variables. The results, corresponding to HgCdTe n 1 -on-p backside illuminated photovoltaic (PV) diodes, are compared with published Monte Carlo results and with analytical (1-D) special cases. For a given pitch, smaller diodes have lower crosstalk, but also lower quantum efficiency. This implies an optimal diode size. The highest quantum efficiency is obtained for low junction depths (1 mm), and the optimum diode size, maximizing the quantum efficiency and minimizing the crosstalk, lies in the range of 15 to 30 mm for a pitch of 50 mm over a wide range of diffusion lengths. The quantum efficiency de- pends weakly on the pitch, for a given ratio of diode size to the pitch. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)02907-X) Subject terms: detector arrays; quantum efficiency; crosstalk; infrared; photodi- ode.

The noise-equivalent-temperature difference (NETD) is calculated in fixed-pattern-noise-limited mercury cadmium telluride (MCT) focal-plane arrays (FPA5) for both 3- to 5-μm and 8- to 14-μm terrestrial imaging applications, on the basis of a model for MCT in which a linear two-point compensation scheme is considered. The contributions to the NETD from the fixed-pattern noise of an array-in terms of gain, offset, and residual error-are calculated and taken in quadrature to obtain the NETD of the FPA. The effect of stability of the focal-plane temperature is included, but the contribution of readout is not considered. The largest contribution to the NETD is from the residual error in the compensation scheme. Decreasing the intrascene temperature difference and including a sharp-cutoff filter are shown to decrease the NETD. The composition has been varied so as to obtain the lowest NETD in each band: at x = 0.31 in the 3- to 5-μm band, and at x = 0.22 to 0.23 in the 8- to 14- μm band (where x is the composition in the alloy Hg 1- x Cd x Te).

A model is presented to calculate response nonuniformity in a hybrid mercury cadmium telluride focal plane array in terms of material/ device parameters. The model predicts a minimum 10% intrinsic nonuniformity contribution from the IR detector array caused by compositional variations in detector material with the state-of-the-art HgCdTe material. In hybrid FPAs an additional contribution to the nonuniformity is caused by variations in the charge injection efficiency across the area of the array. The injection nonuniformity contribution can, however, be controlled to negligibly small values by working at very high injection efficiencies, on the order of 99%.

Because of the similarities in the psychiatric symptoms of Cushing's syndrome and those of major depression, and because the former generally remits when the hyperadrenalism is alleviated, an open clinical trial of the effect of steroid suppression in major depression was undertaken. Ten patients satisfying the DSM-III-R criteria for major depression, and classified as treatment-resistant, were included. Eight patients completed the study, which consisted of discontinuation of other psychotropic drugs and 2 months' treatment with one or more steroid suppressive agent (aminoglutethimide, ketoconazole and/or metyrapone). Six were classified as responders, and two as partial responders. In six, the improvement has been sustained for longer than 5 months after withdrawing the drugs. Side effects were mild to moderate. These results provide some evidence that steroids are involved in the maintenance of major depression, and that their suppression may lead to a readjustment of the hypothalamic-pituitary-adrenal axis with remission of the depression.

The effect of Zener current, due to the internal field emission in the space-charge region of an n+-p junction, on the zero-bias resistance-area product R o A of narrow-bandgap HgCdTe photodiodes has been investigated theoretically. It is shown that the contribution of this mechanism in these photodiodes could appreciably lower the R o A product in the temperature range of 10 to 100 K.