Moderate Contrast Research Articles

Silicon nitride directional coupler-based polarization beam splitter utilizing shallow ridge waveguides for improved fabrication tolerance

This study presents the design and fabrication of a silicon nitride (Si3N4) asymmetrical directional coupler (DC)-based polarization beam splitter (PBS) utilizing a shallow ridge waveguide structure. The use of Si3N4 with a moderate refractive index contrast and the design of a shallow ridge waveguide enables the DC structure to have a wider coupling gap of approximately 600 nm, which can be readily achieved with standard I-line lithography. The simulation results indicate that the polarization splitting is highly efficient with minimal insertion loss. This is corroborated by the experimental measurements, which show consistent broadband performance. The fabricated polarization beam splitter (PBS) exhibits a high polarization extinction ratio (PER) of over 20 dB for both transverse electric (TE) and transverse magnetic (TM) modes across a broad bandwidth of 120 nm (1500-1620 nm). This work demonstrates the potential of shallow ridge Si3N4 waveguides to enhance the fabrication tolerance and performance of integrated photonic devices.

Enhanced laser absorption and ion acceleration by boron nitride nanotube targets and high-energy PW laser pulses

Enhancing laser energy absorption with energy transfer to fast electrons is crucial for efficient laser-driven ion acceleration. In this work, we present an experimental demonstration of volumetric laser absorption using boron nitride nanotube (BNNT) targets with an average density of 15 of the solid density. We use a PW laser system operating at a pulse duration of 1.2 ps and an energy of 1.3 kJ, reaching intensities of 2 × 1019 Wcm−2 on target with moderate nanosecond contrast (109), to generate energetic ion streams from a 250 µm thick BNNT target. To characterize laser-accelerated ions, Thomson parabola spectrometers, CR-39 nuclear track detectors, and an electron spectrometer are employed. The results are compared to those achieved using flat targets made of polystyrene (PS) of the same thickness. The comparison reveals a 1.5-fold increase in proton maximum energy and a 2.5-fold increase in the maximum energy of heavy ions (C and N) when comparing the BNNT to PS. Moreover, the high-energy ion flux recorded at CR-39 is orders of magnitude higher for the BNNT after cutting off low-energy ions with Al filters. The enhanced ion acceleration is the result of a 2.3-fold increase in the electron temperature for BNNT, as measured by the electron spectrometer. These experimental findings are further validated through two-dimensional particle-in-cell simulations, which confirm the increase in electron temperature due to enhanced laser absorption ascribable to the low density and nanostructure of the BNNT target compared to the flat foil. Published by the American Physical Society 2024

Assessing the interplay of contrast, defocus, and resolution in cryo-EM: a benchmark experiment for limited dataset screening

The selection of defocus ranges for small datasets in cryo-electron microscopy (cryo-EM) is under-researched. We present a comprehensive benchmark experiment that aimed to evaluate the relationship between contrast, defocus, and resolution, particularly in the context of limited datasets. We conducted a detailed analysis of beta-galactosidase, apo-ferritin, and connexin-46/50 datasets to optimize pre-screening strategies for cryo-EM. Our approach involved classifying micrographs based on image contrast using an artificial intelligence (AI) model without considering the defocus level. This method allowed us to investigate the optimal defocus range for pre-screening in a limited dataset and its impact on the overall image processing. The micrographs were categorized into good, moderate, and bad contrast groups. Subsequent analysis revealed that, contrary to the prevailing assumption that lower contrast (associated with lower defocus) leads to higher resolution, in scenarios with limited datasets higher contrast images yield superior resolution. This finding was consistent across all three protein samples, underscoring the critical role of contrast in determining the quality of 3D reconstructions in limited datasets. This significant finding challenges conventional cryo-EM methodologies. In conclusion, our study provides new benchmarks for selecting appropriate contrast and defocus levels in cryo-EM, particularly for screening approaches that use limited datasets. This strategy promises to enhance the data quality and efficiency in structural biology research, particularly in resource-constrained scenarios.

High-efficiency self-focusing metamaterial grating coupler in silicon nitride with amorphous silicon overlay

Efficient fiber-chip coupling interfaces are critically important for integrated photonics. Since surface gratings diffract optical signals vertically out of the chip, these couplers can be placed anywhere in the circuit allowing for wafer-scale testing. While state-of-the-art grating couplers have been developed for silicon-on-insulator (SOI) waveguides, the moderate index contrast of silicon nitride (SiN) presents an outstanding challenge for implementing efficient surface grating couplers on this platform. Due to the reduced grating strength, a longer structure is required to radiate the light from the chip which produces a diffracted field that is too wide to couple into the fiber. In this work, we present a novel grating coupler architecture for silicon nitride photonic integrated circuits that utilizes an amorphous silicon (α-Si) overlay. The high refractive index of the α-Si overlay breaks the coupler’s vertical symmetry which increases the directionality. We implement subwavelength metamaterial apodization to optimize the overlap of the diffracted field with the optical fiber Gaussian mode profile. Furthermore, the phase of the diffracted beam is engineered to focalize the field into an SMF-28 optical fiber placed 55 µm above the surface of the chip. The coupler was designed using rigorous three-dimensional (3D) finite-difference time-domain (FDTD) simulations supported by genetic algorithm optimization. Our grating coupler has a footprint of 26.8 × 32.7 µm2 and operates in the O-band centered at 1.31 μm. It achieves a high directionality of 85% and a field overlap of 90% with a target fiber mode size of 9.2 µm at the focal plane. Our simulations predict a peak coupling efficiency of − 1.3 dB with a 1-dB bandwidth of 31 nm. The α-Si/SiN grating architecture presented in this work enables the development of compact and efficient optical interfaces for SiN integrated photonics circuits with applications including optical communications, sensing, and quantum photonics.

Different donors' effect on the electrochemical behavior and electrochromic performances of the D-A type chlorinated polymers

Chlorination has proved to be an efficient method in tuning energy levels and optoelectronic properties of organic semiconducting materials with cheaper synthesis and low-cost raw materials when compared with the fluorinated analogues. Herein, in this work, 5-chlorobenzo[c][1,2,5]thiadizole (Cl-BT) unit was chosen as a new acceptor unit to design two new D-A type electrochromic conjugated polymer: P(Cl-T) and P(Cl-EDOT). The electrochemical behavior and electrochromic performances of above-mentioned chlorinated polymers were studied by electrochemical polymerization techniques and spectroelectrochemistry. Thanks to the strong electron-withdrawing ability of Cl-BT unit and the strong electron-donating properties of EDOT unit, the resultant Cl-EDOT precursor could electropolymerize into high quality hybrid polymer films at lower potential (0.71 V vs. Ag/AgCl) with favorable redox activity and better redox stability. Spectroelectrochemistry shown that as-formed lower band gaps P(Cl-EDOT) exhibits reversible color-changing nature from pale blue to gray accompanied with the moderate optical contrast (13.9%), fast response time (0.6 s), and favorable coloration efficiency (126.4 cm2 C−1) in the NIR region that was measured from the kinetic studies. By optimizing the tested electrolyte and solution, its electrochromic performance is further improved (optical contrast: 25.6%, response time: 0.25 s, coloration efficiency: 275.9 C−1 cm2). The favorable redox stability and electrochromic performance of P(Cl-EDOT) make it a good candidate to construct electrochromic device, and Cl-BT unit should be a promising building block in designing high performance near infrared electrochromic materials.

Using head-mounted eye trackers to explore children's color preferences and perceptions of toys with different color gradients.

This study investigated how color gradients affect the attraction and visual comfort of children aged 4 to 7 years. We analyzed 108 eye-tracking datasets, including the color attraction index (COI), visual comfort index (PUI), and saccade rate (SR). The findings revealed that children are more attracted to colors as saturation decreases and brightness increases within a specific range. Beyond this range, reduced saturation diminishes color appeal. Moderate brightness and contrast enhance visual comfort during play, while extremely low contrast hinders concentration. Warm colors (red, orange, and yellow) slightly dominate preferences; however, the roles of hue, saturation, and brightness in children's color preferences remain inconclusive. These insights have practical implications for age-appropriate toy design and marketing. Future research should explore age-specific color preferences for more targeted design strategies.

Electrochromic conjugated polymers employed tetraphenylethylene building block with moderate optical contrast and fast response time

Tetraphenylethylene (TPE) can improve nature-state transmittance and response time when used as a building block in electrochromism. Two precursors of TPE-based molecules (TPE‐2T and TPE-2E) were successfully synthesized by Stille coupling reaction, and electropolymerized to yield the corresponding polymers of P(TPE‐2T) and P(TPE-2E). Characterizations of the above polymers were performed by cyclic voltammetry (CV), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Furthermore, the spectroelectrochemistry and electrochromic properties of P(TPE‐2T) and P(TPE-2E) were compared investigated. P(TPE‐2T) demonstrated yellow in the neutral state to deep green in the oxidized state while P(TPE-2E) showed colorless-to-violet color changes with 0–1.4 V. P(TPE‐2T) displayed much better electrochromic performance due to its electroactivity with moderate optical contrast (32%) and fast response time (0.9 s). However, P(TPE-2E) showed low optical contrast, which is in agreement with the spectroelectrochemistry result (only slight wavelength shift between the neutral state and the oxidized state). From these results, P(TPE‐2T) can be further explored electrochromic material towards indoor electrochromic product and flexible display.

Layers of inhibitory networks shape receptive field properties of AII amacrine cells

In the retina, rod and cone pathways mediate visual signals over a billion-fold range in luminance. AII ("A-two") amacrine cells (ACs) receive signals from both pathways via different bipolar cells, enabling AIIs to operate at night and during the day. Previous work has examined luminance-dependent changes in AII gap junction connectivity, but less is known about how surrounding circuitry shapes AII receptive fields across light levels. Here, we report that moderate contrast stimuli elicit surround inhibition in AIIs under all but the dimmest visual conditions, due to actions of horizontal cells and at least two ACs that inhibit presynaptic bipolar cells. Under photopic (daylight) conditions, surround inhibition transforms AII response kinetics, which are inherited by downstream ganglion cells. Ablating neuronal nitric oxide synthase type-1 (nNOS-1) ACs removes AII surround inhibition under mesopic (dusk/dawn), but not photopic, conditions. Our findings demonstrate how multiple layers of neural circuitry interact to encode signals across a wide physiological range.

Contrast media extravasation injury: a prospective observational cohort study

ObjectiveTo identify the risk factors for moderate and severe contrast media extravasation and provide effective guidance to reduce the degree of extravasation injuries.MethodsWe observed 224 adult patients who underwent contrast media extravasation at Xiangya Hospital of Central South University, Hunan Provincial Maternal and Child Healthcare Hospital, and Xiangya Changde Hospital, Hunan Province between January 1, 2018 and December 31, 2022. Risk factors for moderate extravasation injuries were evaluated using univariate and multivariate logistic regression.ResultsAmong 224 patients, 0 (0%) had severe, 18 (8.0%) had moderate, and 206 (92.0%) had mild contrast media extravasation injury. Multivariate logistic regression analysis revealed malignant tumors (odds ratio [OR] = 6.992, 95% confidence interval [CI]: 1.674–29.208), Iohexol (OR = 9.343, 95% CI 1.280–68.214), large-volume (> 50 mL) extravasation (OR = 5.773, 95% CI 1.350‒24.695), and injection site (back of the hand) (OR = 13.491, 95% CI 3.056–59.560) as independent risk factors for moderate injury.ConclusionRisk factors for moderate contrast media extravasation injury are malignant tumors, iohexol, large-volume (> 50 mL) extravasation, and back-of-the-hand injection. Analysis of these risk factors can help reduce the degree of injury after extravasation.Clinical relevance statementHigh-risk patients with extravasation support should choose the appropriate contrast media type, avoiding back-of-the-hand injections. We recommend that patients with cancer be implanted with a high-pressure resistant central venous catheter and receive effective measures to timely detect and reduce extravasation.

Effects of contrast and ambient illumination on visual discomfort of autostereoscopic display

AbstractThe conflict between vergence and accommodation is the main perceptual factors contributing to visual discomfort when viewing autostereoscopic display. The key factors relevant to the accommodation and vergence are the ambient illumination and the contrast. The current study was a 2 × 3 × 3 mixed design comparing VFSI and VIMS symptoms between 2D and 3D video clips with three contrast levels under three ambient illumination levels on the autostereoscopic display. Twenty participants were required to evaluate the degree of discomfort by filing out questionnaires after watching those video clips. According to the result analysis, the 3D viewing participants reported more severe symptoms compared to 2D. The moderate contrast conditions were found to be the optimum for viewing comfort. The difference between VFSI and VIMS symptoms become larger with increasing contrast. The results also suggested the optimum 3D illumination condition should not be too high to effectively relieve visual discomfort. VIMS symptoms were more sensitive to the changes in ambient illumination than VFSI. Moreover, significant interaction between contrast and ambient illumination was found. Participants felt the most comfortable in the combination effect of moderate level of contrast and the high level of ambient illumination.

Predicting disease progression and the need for tumor-directed treatment in tectal plate gliomas.

Tectal plate gliomas are rare, slow-growing tumors of the midbrain that are discovered predominantly in the pediatric population. Because of their indolent nature, treatment mainly consists of observation and management of hydrocephalus. Unfortunately, a subset of tectal gliomas may exhibit tumor enlargement and disease progression. Currently, there are no established guidelines for predicting future progression of tectal gliomas or the need for tumor-directed treatment. In this paper, the authors present a large case series of tectal plate gliomas with the aim of determining early indicators of tumor progression and the need for tumor-directed treatment in a pediatric population, along with providing their experience in treating progressive tumors. A retrospective chart review of 170 patients diagnosed with tectal plate glioma from a single institution, of whom 67 were pediatric patients (≤ 18 years of age), was performed. Univariate analysis was used to determine statistically significant predictors of symptomatic disease progression requiring eventual tumor-directed therapy. The median patient age of the full cohort was 24 years (range 0-73 years). Compared with the pediatric population, the adult population had more instances of incidental lesions (p < 0.001) and lower rates of hydrocephalus (50% vs 84%, p < 0.001). Of the pediatric patients who had ≥ 5 years of follow-up (n = 51), 12 (24%) experienced radiological progression and 13 (25%) required treatment for their tumor. The 1-year, 5-year, and 10-year radiographic progression-free survival (PFS) rates were 98%, 90%, and 86%, respectively. In univariate analysis, lesion involvement of the pons, moderate T1 hypointensity, and moderate contrast enhancement on baseline radiology were significantly associated with worse radiographic PFS. Alternatively, significant predictors of requiring tumor-directed treatment included extraocular eye movement abnormalities at presentation, involvement of the lesion beyond the tectum on baseline radiology, moderate T1 hypointensity, moderate contrast enhancement, and an increase in total lesion size during progression. At the most recent follow-up, 94% of the patients had stable/nonprogressive disease, 2% had progressive disease, and 4% died of tumor progression. Patients who demonstrate radiographic progression may not necessarily experience clinical/symptomatic progression or require tumor-directed treatment. Certain patient presentation characteristics and baseline radiographic features may be predictive of worse radiographic PFS or the need for future tumor-directed treatment in the pediatric population. Typically, the natural history of these lesions lends to excellent long-term survival, even in patients who experience clinical progression, should appropriate treatment be initiated.

Operator-norm resolvent estimates for thin elastic periodically heterogeneous rods in moderate contrast

We provide resolvent asymptotics as well as various operator-norm estimates for the system of linear partial differential equations describing thin infinite elastic rods with material coefficients that rapidly oscillate along the rod. The resolvent asymptotics is derived simultaneously with respect to the rod thickness and the period of material oscillations, which are taken to be of the same order. The analysis is carried out separately on two invariant subspaces pertaining to the out-of-line and in-line displacements, under the assumption on material symmetries as well as in the general case when these two types of displacements are intertwined.

342 Predicting Early Disease Progression in Tectal Plate Gliomas

INTRODUCTION: Tectal gliomas are slow-growing tumors of the midbrain. Due to their indolent nature, treatment mainly consists of observation and management of hydrocephalus. However, a subset of tectal gliomas may exhibit tumor enlargement and disease progression. Currently, there are no established guidelines for predicting future progression of tectal gliomas. Further, given the rarity of these tumors, studies in the literature are limited to &lt;50 patients. METHODS: We performed a retrospective chart review of 172 patients diagnosed with tectal glioma. In addition to descriptive statistics, we performed univariate analysis using Student’s t-test and Chi-squared testing to determine if significant differences exist between patients with tumor progression versus those without progression. RESULTS: The median patient age was 24 years (range: 0-73 years); of these, 69 were pediatric (≤18 years). Hydrocephalus was present in 64% of cases. Lesions were incidentally detected in 37% of the cohort and were only present in the adult population. Of the patients that had &gt; 1 year follow-up (n = 145), 26 experienced radiological progression (18%) with 19 requiring tumor-directed treatment (13%). Predictors of progression included younger age at diagnosis (p = 0.005), expansion of the lesion beyond the tectum on initial imaging (p &lt; 0.001), moderate T1 signal (p &lt; 0.001), and mild or moderate contrast enhancement (p = 0.011 and p &lt; 0.001, respectively). At most recent follow-up, 92% had stable disease, 3% had progressive disease, 1% died from tumor progression, and 3% died of other causes. CONCLUSIONS: Certain characteristics of radiographic imaging may be predictive of future disease progression. In patients with progression, excellent survival can be achieved if progression is detected early and appropriate treatment is initiated.

Recurrence Following Globe Sparing Excision for Basal Cell Carcinoma with Anterior Orbital Invasion.

Globe-sparing excision for periocular basal cell carcinoma (BCC) with orbital invasion has evident benefits, but the ensuing morbidity and characteristics of recurrence are not well elucidated. This study aims to describe the extent of visual morbidity following globe-sparing excision, and the clinicoradiological characteristics of tumor recurrence. Multicentre retrospective case series. Eight patients were identified for inclusion in this series. Time to recurrence following globe-sparing excision ranged from 3 to 12 years. Seven patients (87.5%) presented with recurrent disease originating from the medial canthus. Clinical features at presentation included contracture ( n =4, 50.0%), upper lid ptosis ( n =3, 37.5%), a palpable mass ( n =2, 25.0%), and hypoesthesia ( n =2, 25.0%). Radiologically, tumor recurrence was predominantly characterized by isointense signals on T1 and T2-weighted sequences ( n =5, 62.5%) with moderate contrast enhancement. The most common histologic subtype in recurrent tumors was a mixed nodular and infiltrative growth pattern ( n =5, 62.5%). Perineural invasion was a feature in four (50%) cases. Salvage therapy in the form of exenteration was performed in seven cases. Vismodegib and adjuvant radiotherapy were provided for one case with surgically unresectable tumor recurrence. Globe-sparing excision for invasive periocular BCC can be complicated by late recurrence that develops rapidly despite silent neuroimaging for years. Early clinical signs are subtle. High-risk features predictive of recurrence include medial canthus location, mixed histological subtypes, and perineural invasion. Patients with such characteristics require lifelong clinical and imaging surveillance following globe-sparing excision.

Effective properties of heterogeneous materials as functions of contrast between properties of constituents

One of the key difficulties in applications of the effective media theories to real materials is the complex and “irregular” character of microstructures. However, in cases of moderate contrast between properties of the constituents, the sensitivity of the effective properties to microgeometries is much lower; it vanishes in the first approximation. The latter actually remains applicable at substantial (up to 70%–100%) contrast in properties. The effective elastic and conductive properties are considered as functions of property contrast between constituents. Whereas in the isotropic cases the Voigt–Reuss bounds provide guidance, in anisotropic cases these issues are less obvious. Two origins of effective anisotropies are discussed: (A) anisotropy of material constants and (B) geometric factors: non-random orientations of non-spherical inclusions. To the first order in contrast, the factor (A) is dominant, and factor (B) can be ignored (effective properties are independent of microgeometries, such as inhomogeneity shapes); the importance of factor (B) increases sharply with increasing contrast. For matrix composites (continuous matrices containing inhomogeneities), an interesting interplay takes place between the moderate contrast assumption and the non-interaction assumption (NIA). It shows that, in cases of moderate contrast, the NIA remains accurate at substantial concentrations. An application to monitoring fatigue of austenitic steel, whereby property contrast between the martensite and austenite phases is moderate, is discussed. Results of the second order in contrast, that are limited to the ellipsoidal inhomogeneities, are also given.

Inter and intra-observer agreement of arterial wall contrast-enhanced ultrasonography in giant cell arteritis.

The aim of this study was to analyze inter- and intra-observer agreement for contrast-enhanced ultrasonography (CEUS) for monitoring disease activity in Giant Cell Arteritis (GCA) in the wall of axillary arteries, and common carotid arteries. Giant cell arteritis patients have CEUS of axillary arteries and common carotid. These images were rated by seven vascular medicine physicians from four hospitals who were experienced in duplex ultrasonography of GCA patients. Two weeks later, observers again rated the same images. GCA patients were recruited in from December 2019 to February 2021. An analysis of the contrast of the ultrasound images with a gradation in three classes (grade 0, 1, and 2) was performed. Grade 0 corresponds to no contrast, grade 1 to moderate wall contrast and grade 2 to intense contrast. A new analysis in 2 classes: positive or negative wall contrast; was then performed on new series of images. Sixty arterial segments were evaluated in 30 patients. For the three-class scale, intra-rater agreement was substantial: κ 0.70; inter-rater agreement was fair: κ from 0.22 to 0.27. Thirty-four videos had a wall thickness of less than 2 mm and 26 videos had a wall thickness greater than 2 mm. For walls with a thickness lower than 2 mm: intra-rater agreement was substantial: κ 0.69; inter-rater agreement was fair: κ 0.35. For walls with a thickness of 2 mm or more: intra-rater agreement was substantial: κ 0.53; inter-rater agreement was fair: κ 0.25. For analysis of parietal contrast uptake in two classes: inter-rater agreement was fair to moderate: κ from 0.35 to 0.41; and for walls with a thickness of 2 mm or more: inter-rater agreement was fair to substantial κ from 0.22 to 0.63. The visual analysis of contrast uptake in the wall of the axillary and common carotid arteries showed good intra-rater agreement in GCA patients. The inter-rater agreement was low, especially when contrast was analyzed in three classes. The inter-rater agreement for the analysis in two classes was also low. The inter-rater agreement was higher in two-class analysis for walls of 2 mm thickness or more.

Color-tuning neutrality for soluble black-to-transmissive electrochromics via solution co-processing

Chemical polymerization towards obtaining alternating copolymers ECP-B and ECP-R of the electron-acceptor (2,2′-biindoline)-3,3′-dione or benzotriazole and the electron-donor thiophene derivatives, with or without long alkyl chain substituents serving as solubilization components, was performed in advance. Electrochromic studies demonstrated that ECP-B transformed from neutral-state blue to an oxidized-state transmissive light cyan color, while ECP-R displayed a red color in the neutral state and a transparent light gray color in the oxidized state. Then, the neutral-state black polymer electrochrome (ECP-2) was obtained by blending two donor-π-acceptor (D-π-A) copolymers with complementary spectral absorption via solution co-processing in different mix ratio. The film ECP-2 in 1:2 mass ratio of ECP-R to ECP-B demonstrated a full range of visible absorption, and switched between an improved saturated black neutral state (L* = 57.3, a* = 4, b* = −7) and a light cyan transmissive oxidation state (L* = 77.6, a* = −4, b* = −5) reversibly with the moderate optical contrast of ca. 30%, the fast switching speed as low as 1.2 s, and the high coloration efficiency (222 cm2·C-1), which suggested a promising method for large area electrochromic device applications. Besides, a larger contrast (65.9%) in NIR region (1500 nm) for the ECP-2 film concomitant with an outstanding coloring efficiency (515 cm2·C-1) and a fast response time (0.6 s) were favorable for many NIR applications.

Effects of nutrient heterogeneity on root foraging and plant growth at the individual and community level.

Plants enhance nutrient uptake in heterogeneous nutrient environments through selective root placement. Many studies have documented that plants grow better under heterogeneous than under homogeneous nutrient distribution, but comprehensive syntheses are relatively few. In a meta-analysis, we examined the effects of patch scale and contrast on plant responses by synthesizing the effects of nutrient heterogeneity on root foraging and plant growth in 131 comparative studies. Plant responses to nutrient heterogeneity were phylogenetically conserved, and the response in shoot biomass was significantly correlated with the response in root biomass but not with root foraging precision. Root precision depended on the competition regime, and plants had lower precision in interspecific than in conspecific competition. Community-level growth was significantly promoted by nutrient heterogeneity and was less variable than individual-level responses. Along with increasing patch scale, overall shoot and root responses of individuals increased but root foraging precision declined. In addition, moderate patch contrast induced the highest root responses. Our results indicate that plants optimize nutrient acquisition from heterogeneous patches mainly through increasing root growth, and plant communities exploit heterogeneous nutrients more effectively than individuals. Understanding the roles of patch attributes in nutrient-heterogeneity effects may help in designing fertilization practices to promote productivity and conserve biodiversity.

Using multiple partially-penetrating wells (MPPWs) to improve the performance of high-temperature ATES systems: Well operation, storage conditions and aquifer heterogeneity

The occurrence of free thermal convection negatively affects thermal recovery efficiencies of High-Temperature Aquifer Thermal Energy Storage (HT-ATES) systems. In this study the potential of applying a Multiple Partially Penetrating Well (MPPW) configuration to counteract the impact for seasonal HT-ATES is tested through numerical modeling with SEAWATv4. For scenarios where the thermal front is close to the HT-ATES well-screen and free thermal convection has considerable effect on the thermal recovery efficiency, the use of a MPPW configuration has great potential. Storage at a moderate temperature contrast (ΔT = 40 °C) between the hot injection volume and cold ambient groundwater in a high-permeability aquifer resulted in significant improvement of the thermal recovery efficiency with a MPPW configuration targeting injection in lower parts of the aquifer and recovery in the upper parts. For conventional, fully screened HT-ATES a thermal recovery efficiency of 0.43 is obtained while this is 0.59 with the MPPW scheme in the first recovery cycle. This recovery efficiency of 0.59 is only 0.11 less than a theoretical case with no buoyancy effects. For seasonal HT-ATES cases that face severe free thermal convection, rapid accumulation of heat in the upper part of the aquifer is observed and the MPPW configuration is less effective due to the long period between injection and recovery. Especially for HT-ATES cases that require a cut-off temperature, thermal recovery can be significantly improved and prolonged. For storage temperatures of 60 and 80 °C in a high-permeability aquifer, approximately 4 times more abstracted usable heat is obtained with the MPPW setup while considering a cut-off temperature of 40 °C. Moreover, the present study shows that the use of MPPW configurations in heterogeneous aquifers should be carefully planned. Improper application of MPPW is particularly vulnerable for simplification of the aquifer characteristics, and therefore proper site heterogeneity investigation and operational monitoring are required to benefit from optimal MPPW operation during HT-ATES.

Frontal intradiploic encephalocele in a 44-year-old male patient: illustrative case.

Encephaloceles are protrusions of the cerebral tissue through a skull defect. They occur mostly in children and very rarely in adults. The authors present a case of a 44-year-old man presenting with a first-time generalized seizure. Computed tomography of the head showed bone destruction associated with a right frontal lesion. Magnetic resonance imaging scans demonstrated a largely isointense lesion in the intradiploic space that contained small, hyperintense nodular components and showed a low to moderate contrast agent enhancement. The patient underwent resection, during which the histological examination found the lesion to be an intradiploic encephalocele. The patient had an uneventful postoperative course with a cessation of seizures. The imaging and neuropathological findings as well as a literature review, together with a discussion on the etiology of intradiploic encephaloceles, are contained in this report.