Current Off Research Articles

Poster 167: Increased Throwing Velocity is Correlated with a Higher Likelihood of Violating Current Pitch Count Recommendations in High School Baseball Pitchers.

Objectives: While pitch count and rest guidelines have been promoted for youth and adolescent baseball players for nearly two decades, compliance with guidelines remains poorly understood. The purpose of this study was to determine the frequency of compliance with Pitch Smart guidelines, as well as the association between compliance and range of motion, strength, velocity, injury, and pitcher utilization. Methods: This study was a prospective, multi-center study of high school pitchers, encompassing each region of the United States. Pre-season pitchers were surveyed about their compliance with current off- season rest-related guidelines and history of injury. Pre-season, pitchers underwent standardized physical examinations and pitch velocity was measured. During the high school season that followed, both pitch counts and injury incidence were collected. Results: One hundred and fifteen pitchers participated. Based upon pre-season data, 84% of pitchers had previously violated current pitch recommendation guidelines. During the season, 14% had at least one instance of a violation of the current pitch counts guidelines. Across both the pre-season survey and in-season pitch counts, 89% of players had at least one violation of the current Pitch Smart guidelines. While there were no significant differences in range of motion or strength, those pitchers who were non-compliant with guidelines in the pre-season had higher max pitch velocity (mean±standard deviation 74±8 miles per hour vs. 69±5 miles per hour, p=0.009). Pitchers self-reported their peak velocity at 7 MPH greater than the actual measured velocity. Only a single injury occurred during the season, precluding a comparison between groups. There were no significant differences in the incidence of a history of injury between those pitchers who were noncompliant with between-season rest guidelines (p=0.285). Conclusions: Most high school pitchers are non-compliant with current Pitch Smart guidelines, and they tend to overestimate their peak velocity by 7 MPH. Pitchers with greater velocity were at the highest risk for violating current pitch count recommendations. Since both increased throwing volume and pitch velocity are known risk factors for injury, these athletes may be at particular risk for subsequent injury. research is necessary to understand whether taking three consecutive month rest between seasons prevents pitching-related injury.

Topographically Generated Submesoscale Shear Instabilities Associated with Brazil Current Meanders

Abstract The western boundary current system off southeastern Brazil is composed of the poleward-flowing Brazil Current (BC) in the upper 300 m and the equatorward flowing Intermediate Western Boundary Current (IWBC) underneath it, forming a first-baroclinic mode structure in the mean. Between 22° and 23°S, the BC-IWBC jet develops recurrent cyclonic meanders that grow quasi-stationarily via baroclinic instability, though their triggering mechanisms are not yet well understood. Our study, thus, aims to propose a mechanism that could initiate the formation of these mesoscale eddies by adding the submesoscale component to the hydrodynamic scenario. To address this, we perform a regional 1/50° (∼2 km) resolution numerical simulation using CROCO (Coastal and Regional Ocean Community model). Our results indicate that incoming anticyclones reach the slope upstream of separation regions and generate barotropic instability that can trigger the meanders’ formation. Subsequently, this process generates submesoscale cyclones that contribute, along with baroclinic instability, to the meanders’ growth, resulting in a submesoscale-to-mesoscale inverse cascade. Last, as the mesoscale cyclones grow, they interact with the slope, generating inertially and symmetrically unstable anticyclonic submesoscale vortices and filaments. Significance Statement Off southeastern Brazil, the Brazil Current develops recurrent cyclonic meanders. Such meanders enhance the open-ocean primary productivity and are of societal importance as they are located in a region rich in oil and gas where oil-spill accidents have already happened. This study aims to explore the processes responsible for triggering the formation of these mesoscale eddies. We find that incoming anticyclones reach the slope upstream of separation regions and generate barotropic instabilities that eject submesoscale filaments and vortices and can trigger the meanders’ formation. Such results show that topographically generated submesoscale instabilities can play an important role in the dynamics of mesoscale meanders off southeastern Brazil. Moreover, this may indicate that resolving the submesoscale dynamics in operational numerical models may contribute to an increase in the predictability of the regional eddies.

A ZVS-Based Non-Isolated High Step-Up DC–DC Converter With Low Voltage Stress for Renewable Applications

A high gain soft switched step-up DC-DC converter is presented in this paper. High gain is achieved at lower duty and turns ratio with a pair of coupled inductors and a voltage multiplier. In addition, an active clamp is incorporated to reduce the voltage stress across the main switch. Hence, switches with lower on-state resistance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_dson</i> ) and lower voltage ratings are employed, reducing both conduction losses and cost. It additionally helps in achieving zero voltage switching (ZVS) to both MOSFETs. By recycling the leakage energy of the coupled inductors, voltage gain is further increased. It also helps to accomplish zero current switching (ZCS) turn-on and off of diodes. This further reduces losses and increases further efficiency. Moreover, the reverse recovery problem of the diodes is also mitigated. The working principle, steady-state analysis, and design guidelines have been carried out. Finally, a 500 W hardware set up with an input voltage range of 20-24 V and output of 400 V at a switching frequency of 50 kHz is built to validate the performance of the proposed converter. The operating efficiency at full load is observed as 95.11%.

InGaN/GaN QWs on tetrahedral structures grown on graphene/SiC

In recent years, flexible nitride LEDs have been developed for applications in fields such as lighting, displays but also medicine and biology. Said nanowire-based flexible LEDs are made of InGaN/GaN core-shell nanowires encapsulated in a polymer matrix, which is peeled off and constitutes the final flexible LED structure. However, the current peel off process is complex and hardly compatible with industrial applications. One solution to this issue could be the Van Der Waals epitaxy of the LED structures on graphene, as this approach is known to ease the separation from the original substrate. However, to realize Van der Waals epitaxy and prevent nucleation of GaN on defects located within the graphene layer, the quality of the graphene needs to be optimized. In this work we employ graphene grown by Chemical Vapor Deposition on SiC, known to be notably less defective than graphene grown on metals or sapphire. In this work, tetrahedral structures of GaN have been grown on monolayer and multilayer graphene on SiC. X-Ray Diffraction measurements confirmed that the GaN followed the crystallographic directions of SiC, implying growth through remote-epitaxy mechanism thanks to the presence of graphene in both cases. Last, InGaN/GaN structures were realized by growth of a 5 period of InGaN/GaN quantum wells on these GaN tetrahedra. Cathodoluminescence as well as photoluminescence measurements revealed the presence of stacking faults and Zinc Blende inclusion, as well as a broad visible emission near 480 nm of quantum wells.

Investigations on material removal rate of reduced graphene oxide coated copper electrodes for electric discharge machining

ABSTRACT In the present work, the reduced graphene oxide (RGO) nanoparticles have been synthesised by modified Hummer’s technique. The RGO powder thus obtained was characterised by X-Ray diffraction analysis (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electront microscopy (TEM). Raman spectra showed the D-band at Raman shift of 1354 cm−1 and G-band at 1606 cm−1 of RGO. TEM analysis exhibited the RGO structure in nanometres. The prepared nanoparticles were mixed with alcohol to form a paste and was coated on standard Copper electrode for experimentation on Electric Discharge Machine (EDM). The influence of process parameters like current, pulse on and pulse-off on the material removal rate were studied using L9 Orthogonal Array of Taguchi Technique using Minitab18.0. Substantial improvement in material removal rate at current of 20 amperes, pulse on time of 90 microseconds and pulse off time of 1 microsecond. It was also found that current and pulse off were significant factors that influenced the material removal rate.

Carbon budgets of copepod communities in the northern Humboldt Current System off Peru

Abundance, biomass and respiration rates of dominant medium- to larger-sized copepod species (ML class) from the upwelling system off Peru (8.5-16°S) were determined along with their carbon ingestion and egestion rates. Small copepods (S class) were included for comparisons of community rates. Overall, abundance/biomass was highest in the upper 50 m and decreased with depth and thus also community ingestion and egestion. Ingestion of the ML class (0-50 m) in shelf regions (14-515 mg C m-2 d-1) was lower in the south compared to the north and central study areas, while their offshore ingestion (11-502 mg C m-2 d-1) was comparable across regions (8.5-16°S). Ingestion rates (0-50 m) of the S class were in a range similar to those of the ML class in shelf regions (100-417 mg C m-2 d-1) but were higher offshore (177-932 mg C m-2 d-1). Calanus chilensis and the S class contributed most to total ingestion in the north, while in the south, Centropages brachiatus had the highest community ingestion aside from the S class. Egestion varied from 3-155 mg C m-2 d-1 for the ML class and 30-280 mg C m-2 d-1 for the S class. The high community rates highlight the crucial role of both size classes for carbon budgets in the northern Humboldt Current System off Peru and indicate that the ML class may enhance passive vertical carbon flux, whereas the S class may support carbon remineralization rates in surface waters.

Oceanographic structuring of the mucous-mesh grazer community in the Humboldt Current off Peru

The Humboldt Upwelling System (HUS) supports high levels of primary production and has the largest single-stock fishery worldwide. The high fish production is suggested to be related to high trophic transfer efficiency in the HUS. Mucous-mesh grazers (pelagic tunicates and gastropods) are mostly of low nutritious value and might reduce trophic transfer efficiency when they are locally abundant. Unfortunately, little is known about the spatial dynamics of mucous-mesh grazers from Peruvian waters, limiting our understanding of their potential ecological role(s). We provide a spatial assessment of mucous-mesh grazer abundance from the Peruvian shelf in austral summer 2018/2019 along 6 cross-shelf transects spanning from 8.5 to 16°S latitude. The community was dominated by appendicularians and doliolids. Salps occurred in high abundance but infrequently, and pelagic gastropods were mostly restricted to the north. At low latitudes, the abundance of mucous-mesh grazers was higher than some key species of crustacean mesozooplankton. Transects in this region had stronger Ekman transport, higher temperature, lower surface turbidity and a broader oxygenated upper water layer compared to higher-latitude transects. Small-scale lateral intrusions of upwelled water were potentially associated with high abundances of doliolids at specific stations. The high abundance and estimated ingestion rates of mucous-mesh grazers in the northern HUS suggest that a large flux of carbon from lower trophic levels is shunted to tunicates in recently upwelled water masses. The data provide important information on the ecology of mucous-mesh grazers and stress the relevance to increase research effort on investigating their functioning in upwelling systems.

Value of 1-Hour Plasma Glucose During an Oral Glucose Tolerance Test in a Multiethnic Cohort of Obese Children and Adolescents.

We applied the current cut off thresholds reported in the pediatric literature for the 1-hr PG, 132.5 (7.4 mmol/l) and 155 mg/dL (8.6 mmol/l) during an OGTT, to report abnormal glucose tolerance (AGT) using ROC curve analyses. We determined the empirical optimal cut point for 1-hr PG for our multi ethnic cohort using the Youden Index. About 1-hour and 2-hours plasma glucose showed the highest predictive potential based on Areas under the curve (AUC) values of 0.91 [CI: 0.85, 0.97] and 1 [CI: 1, 1], respectively. Further comparison of the ROC curves of the 1-hour and 2-hour PG measurements as predictors of an abnormal OGTT showed that their associated AUCs differed significantly (X2(1) = 9.25, P < .05). Using 132.5 mg/dL as the cutoff point for plasma glucose at 1-hour yielded a ROC curve with an AUC of 0.796, a sensitivity of 88%, and a specificity of 71.2%. Alternatively, the cutoff point of 155 mg/dL resulted in a ROC AUC of 0.852, a sensitivity of 80%, and a specificity of 90.4%. Our cross-sectional study affirms that the 1-hr PG can identify obese children and adolescents at increased risk for prediabetes and/or T2D with almost the same accuracy as a 2-hr PG. In our multi-ethnic cohort, a 1-hr PG ⩾ 155 mg/dL (8.6 mmol/l) serves as an optimal cut-point, using the estimation of the Youden index with AUC of 0.86 and sensitivity of 80%.We support the petition to consider the 1-hr PG as integral during an OGTT, as this adds value to the interpretation of the OGTT beyond the fasting and 2-hr PG.

Interaction between Iron Fluoride and Molten FLiBe

The equilibrium potentials of iron in a LiF-BeF2-FeF2 melt were measured using the EMF method and were dependent upon the temperature and iron fluoride concentrations. The empirical equations for the isotherms and equilibrium polytherms of the iron fluoride concentration were obtained. The cathode polarization of iron fluoride in the molten mixture of lithium and beryllium fluoride was measured using the current switch off method from the stationary state. It was found that in the studied temperature and concentration ranges of iron fluoride in the LiF-BeF2 electrolyte, the valence state of iron in the melt is mainly +2. According to the experimental values of the equilibrium potentials of the iron electrode in the LiF-BeF2-FeF2 melt, the conditional standard potentials of iron were calculated relative to the fluoride reference electrode in the molten mixture of lithium and beryllium fluoride. The conditional standard values of the Gibbs energy change were calculated at the formation of iron difluoride from the element in the form of dilute solutions, as were the thermodynamic values (enthalpy and entropy) when iron difluoride was mixed with LiF-BeF2.

Decadal Time‐Series Depletion of Dissolved Oxygen at Abyssal Depths in the Northeast Pacific

AbstractDissolved oxygen depletion in the global ocean is well documented over several decades from the surface ocean to abyssal depths. This decline is especially prevalent in the Northeast Pacific. A significant decline in dissolved oxygen has been measured over 30 years at 4,000–4,100 m depth (Station M) beneath the California Current off central California. Three principal hypotheses examined the relationship of declining oxygen with biological and physical factors over the 30‐year time series. Annual resolution revealed Ekman pumping, coastal upwelling, particulate matter flux, and sediment community oxygen consumption having significant correlations with bottom water dissolved oxygen concentration. Coastal upwelling accounted for 65% of the annual variation in bottom water oxygen concentration. Stepwise regression yielded descriptive models of bottom water dissolved oxygen using coastal upwelling, wind stress and primary production variables. Is continued oxygen depletion in the Northeast Pacific indicative of abyssal regions in the world ocean?

The oxygen minimum zone relative depth is a key driver of dolphin habitats in the northern Humboldt Current System

Highly mobile odontocetes need habitats with environmental conditions with the potential of aggregating enough and high-quality prey, to maximize foraging success. Until now, the characterization of those habitats was in terms of physical and biological indicators of high production, capable of attracting and sustaining prey. Nevertheless, there has been no approach to quantifying the effects of a biophysical characteristic of the ocean with proven effects on the vertical distribution of prey for cetaceans: The oxygen minimum zone (OMZ) depth. In the northern branch of the Humboldt Current System off Peru (~6-18° S), a shallow OMZ (30-50 m) affects the distribution of the Peruvian anchovy (Engraulis ringens), main prey for several marine predators, including dolphins. We hypothesized these predators would aggregate in productive areas, but with preference for places where the relative OMZ depth can constrain prey vertically, making it more accessible and maximizing foraging success. We fitted Bayesian habitat models for three dominant odontocete species in this region, with multiple combinations of environmental covariates, smoothing techniques, and temporal and spatial random effects. Cetacean data came from 23 dedicated surveys spanning 2001-2019. Habitat predictors included the spatial anomalies of sea surface temperature, surface chlorophyl-a, pycnocline depth and OMZ depth. Dusky (Lagenorhynchus obscurus) and common dolphins (Delphinus delphis) preferred productive, cold areas with a very shallow OMZ, regardless of the season, while bottlenose dolphins (Tursiops truncatus) aggregated in both cold and warm waters, also with shallow OMZ. The former two species of higher metabolic demands would maximize energy intake by selecting areas with highly aggregated prey, while the latter, of more moderate metabolic needs and more diverse prey, would exploit less restricted habitats.

The application of an age adjusted D-dimer threshold to rule out suspected venous thromboembolism (VTE) in an emergency department setting: a retrospective diagnostic cohort study

BackgroundVenous Thromboembolic disease (VTE) poses a diagnostic challenge for clinicians in acute care. Over reliance on reference standard investigations can lead to over treatment and potential harm.We sought to evaluate the pragmatic performance and implications of using an age adjusted D-dimer (AADD) strategy to rule out VTE in patients with suspected disease attending an emergency department (ED) setting. We aimed to determine diagnostic test characteristics and assess whether this strategy would result in proportional imaging reduction and potential cost savings.MethodsDesign: Single centre retrospective diagnostic cohort study.All patients > 50 years old evaluated for possible VTE who presented to the emergency department over a consecutive 12-month period between January and December 2016 with a positive D-dimer result. Clinical assessment records and reference standard imaging results were followed up by multiple independent adjudicators and coded as VTE positive or negative.ResultsDuring the study period, there were 2132 positive D-dimer results. One thousand two hundred thirty-six patients received reference standard investigations. A total increase of 314/1236 (25.1%) results would have been coded as true negatives as opposed to false positive if the AADD cut off point had been applied, with 314 reference standard tests subsequently avoided. The AADD cut off had comparable sensitivity to the current cut off despite this increase in specificity; sensitivities for the diagnosis of DVT were 99.28% (95% CI 96.06–99.98%) and 97.72% for PE (95% CI 91.94% to 97.72). There were 3 false negative results using the AADD strategy.ConclusionsIn patients with suspected VTE with a low or moderate pre-test probability, the application of AADD appears to increase the proportion of patients in which VTE can be excluded without the need for reference standard imaging. This management strategy is likely to be associated with substantial reduction in anticoagulation treatment, investigations and cost/time savings.

Evaluation of Climate Change Impacts on the Geographic Distribution of Fritillaria imperialis L. (Liliaceae) (Turkey)

Abstract Fritillaria imperialis is a bulbous plant that has increased commercial value and contributes to rural development in Turkey. It is widely utilized in traditional medicine and pharmacy, and has great potential for use in modern pharmaceuticals in the future. As the effects of climate change on this plant have not been documented, this study aimed to understand how climate change might affect F. imperialis . The methodology of the study was divided into three steps: ( i ) database development, including the current distribution zones of F. imperialis and climatic parameters such as temperature and precipitation data; ( ii ) determination of the plant’s temperature and precipitation requirements; and ( iii ) Ecocrop’s plant climate suitability modeling (PCSM). As a result of the study, it was determined that climatic suitability would decrease below 20% in the plant’s current distribution area between 2,000 m and 3,000 m altitude. For the zones between 500–1,000 m altitude, the climatic suitability will be as high as 100%. Although there are zones where climatic suitability will increase by 2070, the general trend shows that suitability will decrease. This change in the plant ecosystem is explained by the decreased winter precipitation and snowfall but increased temperature and evaporation at higher altitudes. Fritillaria imperialis is expected to shift its geographic distribution to lower altitudes because of climate change.

Study the impact of graphene channel over conventional silicon on DC/analog and RF performance of DG dual-material-gate VTFET

In this article, using a Silvaco TCAD simulator, the impact of Graphene Channel Double Gate Dual Gate Material Vertical tunnel FET on the analog and RF application is studied. We observed better results in DC characteristics such as drain current (ION), leakage current (IOFF), subthreshold swing (SS), DIBL as well as On current Off current ratio (ION/IOFF). Graphene Vertical tunnel FET proves that the structure is a magnificent candidate for analog and high-frequency range applications. The important figures of merit (FOMs) illustrated in this article are analog performance such as transconductance (gm), second-order transconductance (gg2), output conductance (gd), and VIP2. Due to the dual effect of the high mobility/ controllable band gap of graphene channel and band-to-band tunnel, the proposed structure greatly impacts the result.

DDDMOSFET Performance Improvement by Gate Oxide Removal Followed by Silicided Source/Drain Formation in Gate Slots

In this work, the intentional insertion of slots in metal gate (MG) is introduced to solve the dishing issue for the double-diffused drain MOSFET (DDDMOSFET) fabrication. For traditional DDDMOSFET, the gate oxide layer in slots will be reserved to improve the device reliability, which requires an additional photomask to screen the gate/slot regions during the following sidewall formation and source/drain (S/D) implantation. This makes the process more complicated with increased cost. Without that additional photomask, it is proposed that the removal of gate oxide layer in slots can directly allow the floating S/D formation and the followed Ni silicidation there. It is demonstrated that such a novel process can not only relieve the MG dishing issue but can also effectively result in ~16% higher ON current and comparable OFF current for both N- and P-DDDMOSFETs without threshold voltage shift after applying electrical stress on gates. It is also revealed that the floating silicided S/Ds in slots have negligible influence on device breakdown characteristics. By saving one photomask, this work proposes a novel solution for the effective integration of core devices with very small feature sizes and high-voltage (HV) devices with large feature sizes in the same die, which is a common challenge for display driver chip fabrication using high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> /MG (HK/MG) technology.

Neutrophil to lymphocyte ratio, platelet to lymphocyte ratio and one year survival of lung cancer in Sanglah hospital

Background: Lung cancer is ranked third as the most common cancer in Indonesia. The one-year survival rate of advanced-stage non-small cell lung carcinoma (NSCLC) patient is quite low, that is 24.6%. Effective and inexpensive prognostic markers need to be further studied due to an increasing incidence of cancer. Inflammation plays an important role in tumorigenesis and research showed an association of NLR and PLR values with poor prognosis in patients with various solid tumors, but current cut off values still vary. This study wanted to determine the value of NLR, PLR and their relationship with the survival rate of advanced stage NSCLC patients at Sanglah hospital.Methods: A retrospective cohort study using the medical record of 96 advanced-stage NSCLC patients who underwent treatment since January 2018 in Sanglah hospital, was closely monitored for a year since diagnosed. Analysis was performed with ROC, Kaplan Meier analysis, log rank test, and time independent cox regression model.Results: The one-year survival rate of advanced stage NSCLC patient is 14.6%, with median survival 3.26 months. Cut off NLR&gt; 3.37, median survival 2.66, p=0.00. Cut off PLR&gt;178.55, median survival 3.26, p=0.35. Multivariate analysis showed that NLR, HR=2.75 and performance status, HR=1.78 were associated with survival.Conclusions: NLR with cut off &gt;3.37 is associated with one-year survival rate of advanced-stage NSCLC patient. PLR did not have any significant association with one-year survival rate of advanced-stage NSCLC patient.

Current Loop Off Axis Field Approximations With Excellent Accuracy and Low Computational Cost

The current loop is a fundamental building block of cylindrically symmetric magnetic calculations. However, the off-axis magnetic field involves the subtraction of elliptic integrals of the first and second kind, which is computationally expensive, hard to manipulate in equations, and difficult to visualize. By conducting a different binomial series expansion on the original loop integral, a series solution is created, which can be simplified to a set of approximation functions with useful characteristics: exactly correct along the axis and at distance, while in the current loop itself the relative error is limited, computationally simple, highly accurate, and easy to visualize for behavior or symmetry. For the radial field, the first and second orders fit where the parameters are optimized to minimize the relative peak error. Note the symmetry that occurs by expressing as function of the scaled expansion term <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> , which ranges from 0 to 1, allowing maximum relative errors of 0.025 for first order and 2.9E-4 for second order. For the axial field first order, due to the subtraction of terms, the accuracy is only modest but the second order has a 9E-4 maximum relative error, with zero error at the loop, on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z =0$ </tex-math></inline-formula> loop plane. The axial field relative error stays low within the loop, but the outside stays low for any h until it falls to 1% of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z =0$ </tex-math></inline-formula> plane value, then it loses accuracy as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> is near where the field direction reverses sign due to slight differences in the zero crossing predicated coordinate, increasing again in accuracy as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> moves further from the reveal. Higher order approximations for both radial and axial add more <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> terms with increasing accuracy—for radial, the third order is 1.8E-5, fourth order is 2.3E-6, and fifth order is 4.9E-7, while axial goes as third 4.6E-5, fourth 6E-6, and fifth 1.3E-6. Relative error plots in 3-D space are presented for all orders of approximations. The simplicity of these functions suggests new ways combining loops to optimize such things as field uniformity.

Enhanced drain current and cut off frequency in AlGaN/GaN HEMT with BGaN back barrier

The DC and RF capability of GaN high electron mobility transistor (HEMT) was enhanced by incoorporating BGaN back barrier (BB). Different types of back barriers like AlGaN, BGaN, AlN, AlInN, InGaN and p-diamond was used and the small and large signal RF characteristics were simulated and compared at gate length of 0.8 µm. The AlGaN/GaN HEMT with BGaN back barrier exhibited the highest drain current density of 1.45 A/mm at drain voltage of VD = 10 V. Also, the device with BGaN back barrier had a transconductance of 275 mS/mm at drain voltage of VD = 10 V. The highest value of current gain cutoff frequency (fT) of 27 GHz was attained for HEMT with BGaN back barrier. At 100 nm gate length, the device with BGaN back barrier exhibited the highest fT of 118 GHz. The voltage gain of the devices is also simulated, BGaN back barrier device exhibited better performance above 12 GHz. The BGaN back barrier device exhibited better performance in terms of drain current, transconductance, current gain cut off frequency, voltage gain and linearity. Thus, the device with BGaN back barrier has a good potential for high frequency and high gain power applications that require highly linear devices.

Zero voltage switching high step‐up boost converter with coupled inductor for renewable energy applications

AbstractThis paper proposes a zero‐voltage switching high step‐up boost converter with coupled inductor for renewable energy applications. In this proposed circuit, main and auxiliary switches are turned ON at zero voltage switching to reduce switching losses. The voltage gain of the converter is increased by varying the turns ratio between primary and secondary of the coupled inductor (CI). The voltage spikes at the main switch are mitigated by using active clamping technique. The reverse recovery problem in diodes is alleviated due to leakage inductance of the CI. Zero current switching turn OFF in output diode is achieved, which can enhance the efficiency of the converter. A real‐time model for 100 W proposed converter circuit is developed to verify the theoretical analysis.

Microbial production of toluene in oxygen minimum zone waters in the Humboldt Current System off Chile

Expansion of oxygen minimum zones in the world's oceans is likely to enhance the production of anaerobic metabolites by marine microorganisms. Here we show that toluene is present throughout the year in shelf waters of the upwelling ecosystem off Concepción (36° S), Chile, and it is a product of microbial anaerobic metabolism. The intra-annual variability in toluene concentrations is consistent with seasonal variability in the strengths of suboxic equatorial and oxygenated subantarctic water masses. Laboratory incubations of oxygen minimum zone water showed microbial production of toluene in the absence of O2. Toluene concentrations were elevated (up to 96 nM) in deeper O2-depleted waters and followed a seasonal pattern in oceanographic conditions. There is evidence to hypothesize that microbial production of toluene could be a homeostatic biochemical mechanism to thrive in the more acidic oxygen minimum zone waters. On the other hand, evidence indicates that microbial anaerobic degradation of toluene may be a source of NO2− by partial denitrification, as shown for aquifer sediments. Since toluene production was not detected in incubations under aerobic conditions, we hypothesize that oxygen minimum zone waters export toluene to surrounding oxygenated waters. Expansion of hypoxia in the ocean will certainly enhance the production and export of anaerobic metabolites by marine microorganisms.