Small Differences Research Articles

Discrimination and sensorimotor adaptation of self-produced vowels in cochlear implant users.

Humans rely on auditory feedback to monitor and adjust their speech for clarity. Cochlear implants (CIs) have helped over a million people restore access to auditory feedback, which significantly improves speech production. However, there is substantial variability in outcomes. This study investigates the extent to which CI users can use their auditory feedback to detect self-produced sensory errors and make adjustments to their speech, given the coarse spectral resolution provided by their implants. First, we used an auditory discrimination task to assess the sensitivity of CI users to small differences in formant frequencies of their self-produced vowels. Then, CI users produced words with altered auditory feedback in order to assess sensorimotor adaptation to auditory error. Almost half of the CI users tested can detect small, within-channel differences in their self-produced vowels, and they can utilize this auditory feedback towards speech adaptation. An acoustic hearing control group showed better sensitivity to the shifts in vowels, even in CI-simulated speech, and elicited more robust speech adaptation behavior than the CI users. Nevertheless, this study confirms that CI users can compensate for sensory errors in their speech and supports the idea that sensitivity to these errors may relate to variability in production.

ALMA-LEGUS. I. The Influence of Galaxy Morphology on Molecular Cloud Properties

We present a comparative study of the molecular gas in two galaxies from the Legacy ExtraGalactic UV Survey (LEGUS) sample: barred spiral NGC 1313 and flocculent spiral NGC 7793. These two galaxies have similar masses, metallicities, and star formation rates, but NGC 1313 is forming significantly more massive star clusters than NGC 7793, especially young massive clusters (<10 Myr, >104 M ⊙). Using Atacama Large Millimeter/submillimeter Array (ALMA) CO(2–1) observations of the two galaxies with the same sensitivity and resolution (13 pc), we directly compare the molecular gas in these two similar galaxies to determine the physical conditions responsible for their large disparity in cluster formation. By fitting size–line width relations for the clouds in each galaxy, we find that NGC 1313 has a higher intercept than NGC 7793, implying that its clouds have higher kinetic energies at a given size scale. NGC 1313 also has more clouds near virial equilibrium than NGC 7793, which may be connected to its higher rate of massive cluster formation. However, these virially bound clouds do not show a stronger correlation with young clusters than with the general cloud population. We find surprisingly small differences between the distributions of molecular cloud populations in the two galaxies, though the largest of those differences is that NGC 1313 has higher surface densities and lower freefall times.

AI-Based Measurement of Lumbar Spinal Stenosis on MRI: External Evaluation of a Fully Automated Model.

The aim of this study was to clinically validate a fully automated AI model for magnetic resonance imaging (MRI)-based quantifications of lumbar spinal canal stenosis. This retrospective study included lumbar spine MRI of 100 consecutive clinical patients (56 ± 17 years; 43 females, 57 males) performed on clinical 1.5 (51 examinations) and 3 T MRI scanners (49 examinations) with heterogeneous clinical imaging protocols. The AI model performed segmentations of the thecal sac on axial T2-weighted sequences. Based on these segmentations, the anteroposterior (AP) and mediolateral (ML) distance, and the area of the thecal sac were measured in a fully automated manner. For comparison, 2 fellowship-trained musculoskeletal radiologists performed the same segmentations and measurements independently. Statistics included 1-sample t tests, the intraclass correlation coefficient (ICC), Bland-Altman plots, and Dice coefficients. A P value of <0.05 was considered statistically significant. The average measurements of the AI model, reader 1, and reader 2 were 194 ± 72 mm 2 , 181 ± 71 mm 2 , and 179 ± 70 mm 2 for thecal sac area, 13 ± 3.3 mm, 12.6 ± 3.3 mm, and 12.6 ± 3.2 mm for AP distance, and 19.5 ± 3.9 mm, 20 ± 4.3 mm, and 19.4 ± 4 mm for ML distance, respectively. Significant differences existed for all pairwise comparisons, besides reader 1 versus AI model for the ML distance and reader 1 versus reader 2 for the AP distance ( P = 0.1 and P = 0.21, respectively). The pairwise mean absolute errors among reader 1, reader 2, and the AI model ranged from 0.59 mm and 0.75 mm for the AP distance, from 1.16 mm to 1.37 mm for the ML distance, and from 7.9 mm 2 to 15.54 mm 2 for the thecal sac area. Pairwise ICCs among reader 1, reader 2, and the AI model ranged from 0.91 and 0.94 for the AP distance and from 0.86 to 0.9 for the ML distance without significant differences. For the thecal sac area, the pairwise ICC between both readers and the AI model of 0.97 each was slightly, but significantly lower than the ICC between reader 1 and reader 2 of 0.99. Similarly, the Dice coefficient and Hausdorff distance between both readers and the AI model were significantly lower than the values between reader 1 and reader 2, overall ranging from 0.93 to 0.95 for the Dice coefficients and 1.1 to 1.44 for the Hausdorff distances. The investigated AI model is reliable for assessing the AP and the ML thecal sac diameters with human level accuracies. The small differences for measurement and segmentation of the thecal sac area between the AI model and the radiologists are likely within a clinically acceptable range.

A clinical utility evaluation of dual HIV/Syphilis point-of-care tests in non-clinical settings for screening for HIV and syphilis in men who have sex with men

BackgroundDual point-of-care tests (POCTs) for the simultaneous detection of antibodies to HIV and syphilis have been developed. Since community-based organisations (CBO) are effective providers of HIV and syphilis testing among men who have sex with men (MSM), evaluation of the utility of these dual tests at CBO testing services is a high priority. The aim of this study is to determine the feasibility of performing dual HIV-syphilis POCT testing among both users and providers at these non-clinical sites.MethodsThis evaluation assessed the utility of two lateral flow immunochromatographic antibody technologies for dual screening for HIV/syphilis among MSM seeking testing in four CBO testing services in Spain, Slovenia, Latvia, and Ukraine. The study’s conceptual framework divides the concept of feasibility into two inter-related domains, acceptability, and usability and further breaks it down into six subdomains: learnability, willingness, suitability, satisfaction, efficacy, and effectiveness. The feasibility analysis was performed by calculating the median score in 3 stages (for individual questions, subdomains, and domains), using a summated scores method.ResultsThe final sample included 844 participants, 60 of which were found to be HIV test positive (7.1%) and 61 (7.2%) positive on testing for syphilis. There was a small difference (1.1%) when comparing the results of the two dual POCTs under evaluation to the tests routinely used at each site. The inter-rater agreement showed a high concordance between two independent readings. The analysis of the feasibility for the users of the services indicated good satisfaction, suitability, and willingness. In addition, among 18 providers the total mean score showed good acceptability and usability, good willingness, easy learnability, high suitability, and good efficacy, but lower satisfaction and effectiveness. The operational characteristics of both dual study POCTs were well evaluated by providers.ConclusionsThe introduction of dual HIV and syphilis POCTs in CBO testing services for screening of MSM is feasible, with a high acceptability and usability both for users and providers. Implementation of dual POCTs for HIV and syphilis in CBO testing services is an opportunity for scaling up integrated HIV/syphilis testing for MSM.

Hardness of (M)LWE with semi-uniform seeds

Let (D,S,χ,m)-LWEn,q be the LWE problem in matrix form (A,y=As+emodq), where A,s,e are randomly chosen respectively from the seed distribution D over Zqm×n, secret distribution S over Zqn and noise distribution χm over Zm (or Rm), i.e., A←D,s←S,e←χm. For various secret-noise distributions (S,χ), the (D,S,χ,m)-LWEn,q problem is shown to be as hard as some standard worst-case lattice problems, but most of the known results require D to be the uniform distribution over Zqm×n. In this paper, we show that under the standard LWE assumption, the problem (D,S,χ,m)-LWEn,q can still be hard for some distribution D that is not (even computationally indistinguishable from) the uniform distribution over Zqm×n. Specifically, we show that if D is a semi-uniform distribution over Zqm×n (namely, D can be publicly derived from and has a “small difference” to the uniform distribution over Zqm×n), then for appropriate choices of (S,χ), the problem (D,S,χ,m)-LWEn,q is hard under the standard LWE assumption. Moreover, we also show that the semi-uniform MLWE problem is hard under the standard MLWE assumption. As a direct application, our results pave the way to prove the security of public-key encryptions with rounded public keys under the standard (M)LWE assumption.

Smaller Differences in the Comparative Effectiveness of Biologics in Reducing Asthma-Related Hospitalizations Compared With Overall Exacerbations

Evidence on the comparative effectiveness of respiratory biologics remains sparse. We sought to evaluate the comparative effectiveness of omalizumab, mepolizumab, benralizumab, and dupilumab in a matched retrospective cohort of patients with asthma. We identified patients with asthma aged ≥18 years who were incident users of these biologics between November 1, 2018, and June 30, 2023, in administrative claims data from the FDA's Sentinel System and Merative™ MarketScan® Commercial Database. We compared asthma-related exacerbations and hospitalizations in the 12-months since biologic prescription in pairwise comparisons of propensity score-matched cohorts. Covariates used in matching included age, sex, allergic comorbidities, baseline asthma medications use, and the Charlson Comorbidity Index. Incidence rate ratios (IRR) and 95% CIs were estimated using negative binomial regression models. Eight hundred and ninety-three mepolizumab users, 1300 benralizumab, 1170 omalizumab, and 1863 dupilumab patients were identified. The average age was 55 years and two-thirds of the participants were female. At baseline, over 80% of these individuals had an active prescription for an inhaled corticosteroid. Almost half of patients on dupilumab had concomitant nasal polyposis compared to 6-13% of patients on the other biologics. Covariates were balanced after matching. In matched analyses, dupilumab was associated with the lowest incidence of exacerbations over the follow-up period (vs dupilumab): mepolizumab (IRR: 1.36; 95% CI: 1.12-1.64), omalizumab (IRR: 1.33; 95% CI: 1.13-1.58), benralizumab (IRR: 1.19; 95% CI: 1.00-1.41). For exacerbations leading to hospitalizations, benralizumab and mepolizumab were associated with the lowest incidence of hospitalizations and the greatest difference was between mepolizumab vs dupilumab (IRR 0.76; 0.56 - 1.03). Dupilumab was associated with the lowest incidence of overall exacerbations and mepolizumab with the lowest incidence of asthma hospitalizations in this administrative claims-based cohort of individuals with asthma. Despite matching propensity scores, residual confounding, such as baseline eosinophil count, may explain some of these findings.

Synthesis of PEDOT/CNTs Thermoelectric Thin Films with a High Power Factor.

In this study, we have improved the power factor of conductive polymer nanocomposites by combining layer-by-layer assembly with electrochemical deposition to produce flexible thermoelectric materials based on PEDOT/carbon nanotubes (CNTs)-films. To produce films based on CNTs and PEDOT, a dual approach has been employed: (i) the layer-by-layer method has been utilized for constructing the CNTs layer and (ii) electrochemical polymerization has been used in the synthesis of the conducting polymer. Moreover, the thermoelectric properties were optimized by controlling the experimental conditions including the number of deposition cycles and electropolymerizing time. The electrical characterization of the samples was carried out by measuring the Seebeck voltage produced under a small temperature difference and by measuring the electrical conductivity using the four-point probe method. The resulting values of the Seebeck coefficient S and σ were used to determine the power factor. The structural and morphological analyses of CNTs/PEDOT samples were carried out using scanning electron microscopy (SEM) and Raman spectroscopy. The best power factor achieved was 131.1 (μWm-1K-2), a competitive value comparable to some inorganic thermoelectric materials. Since the synthesis of the CNT/PEDOT layers is rather simple and the ingredients used are relatively inexpensive and environmentally friendly, the proposed nanocomposites are a very interesting approach as an application for recycling heat waste.

Combination of Machine Learning and Raman Spectroscopy for Determination of the Complex of Whey Protein Isolate with Hyaluronic Acid.

Macromolecules and their complexes remain interesting topics in various fields, such as targeted drug delivery and tissue regeneration. The complex chemical structure of such substances can be studied with a combination of Raman spectroscopy and machine learning. The complex of whey protein isolate (WPI) and hyaluronic acid (HA) is beneficial in terms of drug delivery. It provides HA properties with the stability obtained from WPI. However, differences between WPI-HA and WPI solutions can be difficult to detect by Raman spectroscopy. Especially when the low HA (0.1, 0.25, 0.5% w/v) and the constant WPI (5% w/v) concentrations are used. Before applying the machine learning techniques, all the collected data were divided into training and test sets in a ratio of 3:1. The performances of two ensemble methods, random forest (RF) and gradient boosting (GB), were evaluated on the Raman data, depending on the type of problem (regression or classification). The impact of noise reduction using principal component analysis (PCA) on the performance of the two machine learning methods was assessed. This procedure allowed us to reduce the number of features while retaining 95% of the explained variance in the data. Another application of these machine learning methods was to identify the WPI Raman bands that changed the most with the addition of HA. Both the RF and GB could provide feature importance data that could be plotted in conjunction with the actual Raman spectra of the samples. The results show that the addition of HA to WPI led to changes mainly around 1003 cm-1 (correspond to ring breath of phenylalanine) and 1400 cm-1, as demonstrated by the regression and classification models. For selected Raman bands, where the feature importance was greater than 1%, a direct evaluation of the effect of the amount of HA on the Raman intensities was performed but was found not to be informative. Thus, applying the RF or GB estimators to the Raman data with feature importance evaluation could detect and highlight small differences in the spectra of substances that arose from changes in the chemical structure; using PCA to filter out noise in the Raman data could improve the performance of both the RF and GB. The demonstrated results will make it possible to analyze changes in chemical bonds during various processes, for example, conjugation, to study complex mixtures of substances, even with small additions of the components of interest.

Ladz in the Hood: Features of Pasifika English in Drill Rappers from Western Sydney

Despite well-established Pasifika communities in Australia, there has been no examination of the English spoken by members of these communities in the sociolinguistic literature. Yet, research shows that Pasifika English may exhibit key differences from local ‘mainstream’ varieties. In this paper, we present a case study of members of a drill rap group with Pasifika heritage to examine whether Pasifika English features are evident in their speech. We first analyze their monophthong productions and compare these to those of mainstream Australian English speakers. We also analyze their dental fricative realizations to examine whether there is evidence of th-stopping and dh-stopping, commonly described as markers of Pasifika English. Finally, we investigate whether their speech is more syllable-timed than mainstream Australian English. The results show that these speakers produce monophthongs generally consistent with mainstream Australian English vowels, despite some small differences. We also show consistent th-fronting and dh-stopping in their speech, which serves as a marker of their Pasifika heritage. We find a tendency towards more syllable-timed speech; however, this occurs to a lesser extent than has been reported for other Pasifika varieties of English. The results suggest that these speakers index their Pasifika identities by employing indicators/markers of Pasifika English that diverge from mainstream Australian English.

Performance analysis and multi-objective optimization of the offshore renewable energy powered integrated energy supply system

Offshore renewable energy technologies offer a promising prospect for energy supply on offshore islands. However, traditional wind and solar energy sources exhibit strong variability and cannot fully meet the energy demands of users. At the same time, the energy demand of users also has great volatility, so the supply side and demand side of energy cannot match well. Existing renewable energy systems often utilize thermal power generation as a stabilizer for the system, however, this approach is difficult to apply in offshore conditions. This study introduces an innovative multi-energy complementary system that integrates seawater freezing desalination, refrigeration and power-hydrogen-ammonia co-generation, driven by ocean thermal energy, wind energy, and solar energy. The system incorporates the use of a new developed small temperature difference ejector refrigeration cycle to stabilize the entire system and produce low-temperature refrigeration. By utilizing the seawater freezing desalination process to minimize energy conversion losses and balancing fluctuations in multiple energy inputs and user demands through ammonia-hydrogen co-production, this approach effectively minimizes energy waste, enhances energy utilization efficiency, and reduces excess power handling. The purpose is to optimize the configuration of the energy conversion subsystem within the multi-energy complementary multi-effect co-generation system, thus improving the economic feasibility and reliability of the system in providing energy and freshwater supply, ultimately achieving the goals of reducing energy waste, achieving high conversion efficiency, and minimizing equipment investment. This study conducts an economic analysis and optimization of a multi-energy complementary system, utilizing a 2 MW-level OTEC subsystem as a stabilizer. Both equipment investment and operating costs are considered in the economy analysis. The carbon emission reduction performance of this system is evaluated. The performance optimization results show that the system achieves an energy storage efficiency of 65.96 %, and the curtailment rate of this system is only 3.99 %, significantly lower than the 10 % curtailment rate in traditional system. The proposed system can meet the annual electricity demand of 33.09 million kWh, as well as a cooling demand of 546.81 million kWh. Under typical conditions, the ocean thermal energy conversion cycle exhibits a power efficiency of 0.85 % and a refrigeration efficiency of 29.10 %. Meanwhile, it annually reduces CO2 emissions by 2.54 million tons, demonstrating significant environmental benefits. This proposed system is mainly applicable to tropical waters with high surface water temperatures and depths of no less than 600 m worldwide. This study offers a practical and economically beneficial solution for energy and freshwater supply on offshore islands.

Improved gait parameters following surgical revascularization in patients with intermittent claudication

ObjectiveIntermittent claudication (IC) is known to be associated with impaired gait parameters, with a higher incidence of falls and higher oxygen consumption due to uneconomic walking. However, the influence of arterial disobliteration in patients with IC on their gait pattern has rarely been investigated to date. The aim of this study was to examine the gait patterns before and after inflow revascularization by surgical disobliteration of pelvic and inguinal arteries (ie, common iliac artery, external iliac artery, common femoral artery, profound femoral artery, superficial femoral artery) in IC patients. Successful surgical disobliteration of inflow arteries (improvement of ankle brachial pressure index of ≥0.2 and patent common iliac, external iliac, common femoral, profound femoral, and superficial femoral arteries) is known to improve the painless walking distance for patients with IC due to peripheral arterial disease; however, its influence on gait parameters is unclear. We hypothesized that the gait parameters would also improve after surgery. Improved gait parameters can lead to a more economic walking process, lower oxygen consumption, a lower risk of falls, and a higher quality of life. MethodsIn a single-center, exploratory, longitudinal study, we examined the gait parameters of 20 IC inpatients of our hospital before and after surgical disobliteration of pelvic and inguinal arteries. Spatiotemporal parameters such as range of motion of the hip and knee joint, stance phase, cadence, and foot rotation were obtained using the Diers 4Dmotion Lab (Diers International). The gait parameters were obtained under painful walking conditions preoperatively and with the patients walking pain free at the same speed postoperatively. ResultsA total of 20 patients were examined. Surgical revascularization led to a higher walking cadence (mean, plus 7.88 steps; 95.5 steps/min vs 87.6 steps/min; P = .024), an increased range of motion of the hip joint (mean, plus 2.0°; 35.1° vs 33.1°; P = .038), and improved foot rotation (mean, plus 2.0°; 11.0° vs 9.0°; P = .02). Regarding other parameters such as step length, stance phase, and step duration, smaller differences were detected in this study. ConclusionsIn this exploratory study, we found that surgical revascularization of pelvic and inguinal arteries in IC patients improved certain gait parameters. Further studies with larger patient numbers are needed to confirm these data and provide more evidence on this subject.

Processing of Plural Marking in Nouns by German-Speaking Children With Normal Hearing and Children With Cochlear Implants: An Eye-Tracking Study.

Our goal is to understand how the different types of plural marking are understood and processed by children with cochlear implants (CIs): (a) how does salience affect the processing of plural marking, (b) how is this processing affected by the incomplete signal provided by the CIs, and (c) is it linked to individual factors such as chronological age, vocabulary development, and phonological working memory? Sixteen children with CIs and 30 age-matched children with normal hearing (NH) participated in an eye-tracking study. Their task was to choose the corresponding picture to an auditorily presented singular or plural noun. Accuracy, reaction time, and gaze fixation were measured and analyzed with mixed-effect models. Group differences were found in accuracy but not in reaction time or gaze fixation. Plural processing is qualitatively similar in children with CIs and children with NH, with more difficulties in processing plurals involving stem-vowel changes and less with those involving suffixes. Age effects indicate that processing abilities still evolve between 5 and 11 years, and processing is further linked to lexical development. Our results indicate that early implantation seems to be beneficial for the acquisition of plural as indicated by very small between-group differences in processing and comprehension. Processing is furthermore affected by the type of material (i.e., phonetic, phonological, or morphological) used to mark plural and less so by their segmental salience. Our study emphasizes the need to take into account the form of the linguistic material in future investigations at higher levels of processing.

Altered biodistribution of [68Ga]Ga-DOTA-TOC during somatostatin analogue treatment.

The need for an interval between the administration of long-acting Somatostatin Receptor Analogues (SSA) and the [68Ga]Ga-DOTA-TATE PET has been questioned based on recent literature in the new EANM guidelines. Here an earlier studies showed that SSA injection immediately before SSTR PET had minimal effect on normal organ and tumor uptake (1). However, data are scarce and there are (small) differences between [68Ga]Ga-DOTA-TATE and [68Ga]Ga-DOTA-TOC binding affinity, and it remains unknown whether these findings can be directly translated to scans with [68Ga]Ga-DOTA-TOC as well. The purpose of this study was to assess the effect of SSA use on the biodistribution in a subsequent [68Ga]Ga-DOTA-TOC PET/CT and compare this intra-individually across several cycles of SSA treatments. Retrospectively, 35 patients with NENs were included. [68Ga]Ga-DOTA-TOC PET at staging and after the 1st and 2nd cycle of SSA were included. SUVmean and SUVmax of blood, visceral organs, primary tumor and two metastases were determined. Also, the interval between SSA therapy and the PET scan was registered. Treatment with SSA resulted in a significantly higher bloodpool activity and lower visceral tracer uptake. This effect was maintained after a 2nd cycle of SSA therapy. Furthermore, there was an inverse relationship between bloodpool tracer availability and visceral tracer binding and a positive correlation between bloodpool tracer availability and primary tumor tracer uptake. With an interval of up to 5days, there was a significantly higher bloodpool activity than at longer intervals. Absolute comparison of the SUV on [68Ga]Ga-DOTA-TOC PET should be done with caution as the altered biodistribution of the tracer after SSA treatment should be taken into account. We recommend not to perform a scan within the first 5days after the injection of lanreotide.

Regional-Scale Assessment of Burn Scar Mapping in Southwestern Amazonia Using Burned Area Products and CBERS/WFI Data Cubes

Fires are one of the main sources of disturbance in fire-sensitive ecosystems such as the Amazon. Any attempt to characterize their impacts and establish actions aimed at combating these events presupposes the correct identification of the affected areas. However, accurate mapping of burned areas in humid tropical forest regions remains a challenging task. In this paper, we evaluate the performance of four operational BA products (MCD64A1, Fire_cci, GABAM and MapBiomas Fogo) on a regional scale in the southwestern Amazon and propose a new approach to BA mapping using fraction images extracted from data cubes of the Brazilian orbital sensors CBERS-4/WFI and CBERS-4A/WFI. The methodology for detecting burned areas consisted of applying the Linear Spectral Mixture Model to the images from the CBERS-4/WFI and CBERS-4A/WFI data cubes to generate shadow fraction images, which were then segmented and classified using the ISOSEG non-supervised algorithm. Regression and similarity analyses based on regular grid cells were carried out to compare the BA mappings. The results showed large discrepancies between the mappings in terms of total area burned, land use and land cover affected (forest and non-forest) and spatial location of the burned area. The global products MCD64A1, GABAM and Fire_cci tended to underestimate the area burned in the region, with Fire_cci underestimating BA by 88%, while the regional product MapBiomas Fogo was the closest to the reference, underestimating by only 7%. The burned area estimated by the method proposed in this work (337.5 km2) was 12% higher than the reference and showed a small difference in relation to the MapBiomas Fogo product (18% more BA). These differences can be explained by the different datasets and methods used to detect burned areas. The adoption of global products in regional studies can be critical in underestimating the total area burned in sensitive regions. Our study highlights the need to develop approaches aimed at improving the accuracy of current global products, and the development of regional burned area products may be more suitable for this purpose. Our proposed approach based on WFI data cubes has shown high potential for generating more accurate regional burned area maps, which can refine BA estimates in the Amazon.

Numerical Simulation and Optimal Control of Composite Nonlinear Mechanical Parts Casting Process

In order to understand the numerical simulation and optimal control of the casting process of Machine element, the author proposed a study based on the numerical simulation and optimal control of the casting process of composite Machine element. Firstly, the author analyzed the structural characteristics of composite Machine element, introduced them in detail, and studied their casting technology in combination with the actual situation. Secondly, the casting process of composite Machine element was simulated by using numerical simulation method, and the temperature field and flow field in the casting filling and solidification process were analyzed. Finally, selecting square cylinders with different wall thicknesses as typical components, the scheme design of traditional single casting process and multi material composite casting process based on dieless casting composite forming technology were carried out. Finite element numerical simulation and experimental research were conducted on the two processes, respectively. The results indicate that: The casting obtained by the multi material composite casting process almost solidifies simultaneously around 200 seconds later, and the graphite morphology around the casting is Type A, with a length of about 100 um, with small differences and uniform distribution; The minimum difference in tensile strength around the casting is about 3.8%, and the maximum increase in tensile strength value is 21%. This research achievement can provide technical reference for high-performance and high-quality casting of complex iron castings. In order to improve the casting quality, the author optimized the casting process of composite Machine element by numerical simulation.

From neighborhood contexts to human behaviors: Cellphone-based place visitation data contribute to estimating neighborhood-level depression prevalence in the United States

The elucidation of neighborhood-level mental illness is pivotal to effective community need assessment and public health interventions. However, aggregating individual behaviors linked to mental health at the neighborhood level has proven to be a challenge. In this study, we collected place visitation data from extensive mobile phone records as a proxy measure of health behaviors to investigate whether and how the place visitation data can contribute to improving the estimation of nationwide neighborhood-level depression prevalence. Using nationwide place visitation data from 2019, we measured eight types of health behaviors at the neighborhood level in the United States, including positive and negative health behaviors (PNHB) and health service utilization behaviors (HSUB). The study revealed that visitations to different types of places of interest (POI) (i.e., fitness visitation, drinking place (alcoholic beverages) visitation, pharmacy visitation, general hospital visitation, and specialty hospital visitation) were significantly associated with neighborhood-level depression. Incorporating cellphone-based place visitation data (i.e., the proxy of health behaviors) into the models enhanced modeling fitness, with the model that included neighborhood context variables exhibiting the strongest fitness, followed by PNHB, POI features, and HSUB variables. These improvements are greater in models for self-reported mental health status compared to depression. The model fitness exhibits spatial differences, with smaller differences between actual and predicted values in urban areas (2.834) compared to rural areas (2.956) and the Midwest (2.212) compared to other regions. Overall, this study represents the first nationwide investigation of the role of cellphone-based place visitation data in estimating neighborhood-level depression prevalence. It expands a novel conceptual framework for explicating neighborhood-level depression prevalence by incorporating neighborhood-level health behaviors.

Theoretical and experimental study on the secondary heat recovery cycle of the mixed working fluid in ocean thermal energy conversion

The small ocean temperature difference causes the power generation efficiency to not be high while the power generation cost is high; this method has not been commercially applied. Therefore, it is particularly important to find a new thermal cycle to improve the cycle efficiency. In this paper, a new cycle of the ocean temperature difference using a non-azeotropic mixed as working fluid is proposed, and a secondary heat recovery device is added to the solution branch separated by the separator. Theoretical analysis and numerical calculation were used to analyze the relationships between cycle efficiency and working fluid concentration, turbine inlet pressure and cold seawater temperature were obtained. The results show that the maximum cycle efficiency can reach 5.25% by adding a secondary heat recovery device. A 10 kW OTEC experimental system was constructed and analyzed; the system performance was obtained. The efficiency of the experimental system was found to be as high as 3.8%, while the experimental value of the test system was lower than the theoretical calculation value. Finally, the heat transfer coefficients of an evaporator and condenser under these conditions were obtained, which provides basic data and technical support for the engineering application of an OTEC plant.

Investigation on the propagation characteristics of pressure wave during managed pressure drilling

The small difference between formation pressure and fracture pressure in offshore oil and gas reservoirs poses a huge challenge to drilling. Managed pressure drilling (MPD) technology, as a drilling technique that can accurately control bottomhole pressure, is an effective technique to solve this challenge. In MPD technology, the pressure wave propagation behavior and mechanism in the wellbore induced by wellhead backpressure are crucial for parameter design and efficient application. In this paper, pressure wave propagation characteristics and mechanism in gas-liquid flow were investigated with a new proposed pressure wave velocity model that considers inter-phase mass transfer effect. This new model and its solution algorithm were verified with experimental data in literature. The influence of gas invasion stage, drilling fluid type, drilling fluid density and backpressure on pressure wave propagation characteristics were investigated. Results show that the time for pressure wave induced by wellhead backpressure in the wellbore cannot be ignored in the design of the backpressure value during MPD. This propagation time increases with occurrence of gas invasion. Moreover, the propagation time in water-based drilling fluid is longer than that in oil-based drilling fluid, which is because the interphase mass transfer between invaded gas and oil-based drilling fluid. The influence mechanism of high drilling fluid density and wellhead backpressure on pressure wave propagation characteristics is due to the suppression of gas invasion process. These findings could be used as guides in parameters design and optimization in MPD.

Effects of 1-butyl-3-methyl-imidazolium acetate on the solution behavior of melittin: A molecular dynamics study

Ionic liquids posses efficiency as solvents, co-solvents or agents for applications involving biomolecules. Due to the increasing interest in systems containing proteins and ionic liquids, we hereby present results from molecular dynamics simulations on solutions containing the polypeptide melittin in pure water, in the neat ionic liquid 1-butyl-3-methyl-imidazolium acetate ([BMI][OAc]) and in the equimolar [BMI][OAc]/H2O mixture. When compared to the solutions containing the ionic liquid, melittin displays higher mobility and flexibility, lower stability and poorer secondary structure preservation in water. The intramolecular hydrogen bonds in melittin do not play a major role in the structural preservation, but intermolecular hydrogen bonds between melittin and the solvent are important. The micro-solvation of melittin demonstrates that anions and water molecules are in closer contact to melittin, whereas the cations maintain larger distances to the polypeptide. The presence of [BMI][OAc] reduces fluctuation in melittin's structure. Only small differences have been found in the structural arrangement of melittin in the neat ionic liquid and the ionic liquid/water mixture.

Dielectric and Ultrasonic Properties of PDMS/TiO2 Nanocomposites.

This work presents the dielectric and ultrasonic properties of polydimethylsiloxane (PDMS) nanocomposites filled with titanium dioxide nanoparticles. The dielectric study was performed over a very broad range of frequencies (20 Hz-3 THz). The dielectric permittivity was almost frequency-independent in all the composites at room temperature over the whole range of measurement frequencies, and the dielectric losses were very low under these conditions (less than 2). The dielectric permittivity strongly increases with the nanoparticle concentration according to the Maxwell-Garnet model. Therefore, the investigated composites are suitable for various flexible electronic applications, particularly in the microwave and terahertz frequency ranges. Dielectric dispersion and increased attenuation of ultrasonic waves were observed at lower temperatures (below 280 K) due to the relaxation of polymer molecules at the PDMS/TiO2 interface and in the polymer matrix. The relaxation time followed the Vogel-Vulcher law, while the freezing temperature increased with the titanium dioxide concentration due to interactions between the polymer molecules and nanoparticles. The significant hysteresis in the ultrasonic properties indicated that titanium dioxide acts as a crystallization center. This is confirmed by the correlation between the hysteresis in the ultrasonic properties and the structure of the composites. The small difference in the activation energy values obtained from the ultrasonic and dielectric investigations is related to the fact that the dielectric dispersion is slightly broader than the Debye-type dielectric dispersion.