Primary Parameters Of Interest Research Articles

Alternative schedule of temozolomide/capecitabine in neuroendocrine neoplasms.

The chemotherapy regimen capecitabine/temozolomide (CAPTEM) is routinely used in neuroendocrine tumors (NET), with antitumor activity particularly demonstrated in pancreatic or high-grade neuroendocrine neoplasms (NEN). However, different dosing regimens are used, and the optimal schedule remains to be defined. This single-center retrospective analysis assessed the efficacy and safety of CAPTEM in patients with NEN using a schedule starting both compounds simultaneously (temozolomide on days 1-5 and capecitabine on days 1-14 of a 28-day cycle) rather than sequentially. The primary parameters of interest were response rates, progression-free survival (PFS), and toxicities following this treatment regimen, hereinafter referred to as TEMCAP. The study population comprised 40 patients, half of whom (n = 20) had pancreatic NEN, and 9 patients (22.5%) had pulmonary or thymic NETs. The most common histology was NET G3 (n = 15, 37.5%), and 8 patients (20.0%) had a neuroendocrine carcinoma (NEC). Most patients (77.5%) had at least one prior systemic therapy, and 16 patients (40.0%) prior chemotherapy. The median number of TEMCAP cycles was 6 (range 1-16). Median PFS for the highly heterogeneous population was 13.3 months, while the median overall survival was 31.9 months. In total, 14/36 patients (38.9%) exhibited a partial response, and the disease control rate was 75.0%. The safety profile of TEMCAP (at a below-target mean temozolomide dose of 118.85 mg/m2) in our cohort was remarkably good with no toxicities of grade 3 or 4. Taken together, the results of this analysis further support the use of temozolomide/capecitabine in NEN and prompt further assessment of our modified TEMCAP schedule.

Roles of tropical cyclones with varying intensities in the re-distribution of aerosols

The study analyzes three tropical cyclones (TC) with varying intensities, namely BOB02, a deep depression in the Bay of Bengal; Tauktae, an extremely severe cyclone in the Arabian Sea (AS); and Amphan, a supercyclone in the Bay of Bengal, which developed on October 11, 2020, May 13, 2021, and May 16, 2020, respectively. The analysis focuses on studying the re-distribution of the aerosols over the Indian region using these distinct datasets: Modern-Era Retrospective Analysis for Research and Application, version 2 (MERRA2), Integrated Multi-Satellite Retrievals for GPM (IMERG), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Throughout the cyclonic period, which includes the period from the inception of the low-pressure area to its dissipation as well as the pre-cyclonic and post-cyclonic periods (one week prior to and after the cyclonic period, respectively), various parameters related to aerosols and background meteorological conditions were collected. The primary parameter of interest was the aerosol optical depth (AOD). The analysis revealed significant variations in meteorological parameters such as wind speed, temperature, relative humidity, and rainfall along the cyclone track during both the cyclonic and post-cyclonic conditions compared to the pre-cyclonic conditions of these TCs. The AOD surrounding the cyclone track decreases during cyclonic and post-cyclonic conditions compared to pre-cyclonic conditions. This is due to the scavenging of both anthropogenic and natural (dust) aerosols. Conversely, AOD increases along the cyclone track, mainly due to an increase in natural (sea salt) aerosols. During pre-cyclonic conditions, both natural (dust) and anthropogenic (black carbon, organic carbon, and sulfate) aerosols contribute significantly to the total AOD, whereas during pre-cyclonic conditions, the main contributors are natural (sea-salt) aerosols. The coarse-mode particles are more dominant during cyclonic and post-cyclonic conditions than pre-cyclonic ones. Furthermore, our observations indicate that the atmospheric boundary layer (ABL) height increases by ∼0.1–0.6 km along the cyclone track during cyclonic conditions compared to pre-cyclonic conditions. While AOD from the free troposphere (FT) contributes more to the total AOD, contributions from ABL increase, while those from the FT decrease during cyclonic and post-cyclonic conditions.

Enhancing medium voltage underground circuit design: Assessing limitations, thermal influence, and accurate modelling

The research article conducted a study aimed at elucidating the limitations present in existing international standards related to the permissible quantity of medium voltage circuits that can be placed within a single trench. The study also explored important considerations for underground circuits in the context of renewable energy projects, particularly focusing on the crucial roles of capacity and load requirements in cable design. The research employed advanced finite element methods with Composition, Environmental, Structure, and Mechanism (CESM) and mathematical modeling to enhance existing procedures defined by international standards like IEC 60287, 60502, and 60228. The primary parameter of interest was the thermal influence of subterranean XLPE (cross-linked polyethylene) current capacity, considering various factors such as circuit quantities, distances, and depths. Notably, the study made several key findings, including a notable reduction in the current capacity of the underground circuits. This reduction in current capacity was found to vary, ranging from 100 % to 25.75 %. The reduction was attributed to factors such as native soil conditions, circuit separation. The findings furnish valuable insights into the challenges pertinent to medium voltage underground circuit design. Moreover, the paper establishes the accuracy of the proposed process, achieving a precision of 99.4850 ± 0.5150 % for 240 mm2 and 99.3698 ± 0.6301 % for 630 mm2.

Adolescent alcohol use: use of social network analysis and cross-classified multilevel modeling to examine peer group, school, and neighborhood-level influences

ABSTRACT Background: Neighborhood-, school-, and peer-contexts play an important role in adolescent alcohol use behaviors. Methodological advances permit simultaneous modeling of these contexts to understand their relative and joint importance. Few empirical studies include these contexts, and studies that do typically: examine each context separately; include contexts for the sole purpose of accounting for clustering in the data; or do not disaggregate by sex. Objectives: This study takes an eco-epidemiologic approach to examine the role of socio-contextual contributions to variance in adolescent alcohol use. The primary parameters of interest are therefore variance rather than beta parameters (i.e. random rather than fixed effects). Sex-stratified models are also used to understand how each context may matter differently for male and female adolescents. Method: Data come from the National Longitudinal Study of Adolescent to Adult Health (n = 8,534 females, n = 8,102 males). We conduct social network analysis and traditional and cross-classified multilevel models (CCMM) in the full and sex-disaggregated samples. Results: In final CCMM, peer groups, schools, and neighborhoods contributed 10.5%, 10.8%, and 0.4%, respectively, to total variation in adolescent alcohol use. Results do not differ widely by gender. Conclusions: Peer groups and schools emerge as more salient contributing contexts relative to neighborhoods in adolescent alcohol use for males and females. These findings have both methodological and practical implications. Multilevel modeling can model contexts simultaneously to prevent the overestimation of variance in youth alcohol use explained by each context. Primary prevention strategies addressing youth alcohol use should focus on schools and peer networks.

Hypothermia is associated with a low ETCO2 and low pH-stat PaCO2 in refractory cardiac arrest

AimsThe end-tidal carbon dioxide (ETCO2) is frequently measured in cardiac arrest (CA) patients, for management and for predicting survival. Our goal was to study the PaCO2 and ETCO2 in hypothermic cardiac arrest patients. MethodsWe included patients with refractory CA assessed for extracorporeal cardiopulmonary resuscitation. Hypothermic patients were identified from previously prospectively collected data from Poland, France and Switzerland. The non-hypothermic CA patients were identified from two French cohort studies. The primary parameters of interest were ETCO2 and PaCO2 at hospital admission. We analysed the data according to both alpha-stat and pH-stat strategies. ResultsWe included 131 CA patients (39 hypothermic and 92 non-hypothermic). Both ETCO2 (p < 0.001) and pH-stat PaCO2 (p < 0.001) were significantly lower in hypothermic compared to non-hypothermic patients, which was not the case for alpha-stat PaCO2 (p = 0.15). The median PaCO2-ETCO2 gradient was greater for hypothermic compared to non-hypothermic patients when using the alpha-stat method (46 mmHg vs 30 mmHg, p = 0.007), but not when using the pH-stat method (p = 0.10). Temperature was positively correlated with ETCO2 (p < 0.01) and pH-stat PaCO2 (p < 0.01) but not with alpha-stat PaCO2 (p = 0.5). The ETCO2 decreased by 0.5 mmHg and the pH-stat PaCO2 by 1.1 mmHg for every decrease of 1° C of the temperature. The proportion of survivors with an ETCO2 ≤ 10 mmHg at hospital admission was 45% (9/25) for hypothermic and 12% (2/17) for non-hypothermic CA patients. ConclusionsHypothermic CA is associated with a decrease of the ETCO2 and pH-stat PaCO2 compared with non-hypothermic CA. ETCO2 should not be used in hypothermic CA for predicting outcome.

Cell-free DNA Testing in Routine Practice: Characterisation of a Cohort with Positive Results for Trisomies, Sex Chromosome Anomalies and Microdeletions.

Introduction Cell-free DNA (cfDNA) testing is increasingly used as a screening method not only for trisomy (T) 21 but also for T18 and T13, sex chromosome anomalies (SCA) and microdeletions. Based on cases with a positive cfDNA result in our specialised prenatal practice, this study aims to characterise the usage of cfDNA testing and to estimate the positive predictive value (PPV) in routine practice in Germany. Patients and Methods In this retrospective study we analysed the data of all pregnant women with a positive cfDNA result seen between 09/2013 and 12/2019. Women were either referred due to the positive result or the test was initiated in our practice. The primary parameter of interest was the concordance of cfDNA tests with confirmatory genetic testing. Results We encountered 81 cases with a positive cfDNA test (T21: 49.4%; T18: 9.9%; T13: 8.6%; SCA: 22.2%; 22q12del: 8.6%). The PPV was 95.0% for T21, but considerably lower for T18 (55.6%) and T13 (28.6%). For SCAs it was 23.1% and no case with DiGeorge syndrome was confirmed. 63% of the patients had not received a fetal anomaly scan before cfDNA testing. In first-trimester fetuses with a cfDNA test predicting an autosomal aneuploidy, fetal anomalies were detected in 90.3% of the cases. No false positive case had an abnormal US result. Conclusions Despite the excellent specificity of cfDNA tests, the PPV for aneuploidies other than T21 is low in routine practice. In discordance with the current guidelines, cfDNA test is often used without a previous detailed anomaly scan. Our data provide valuable information to assist patient counselling and shared decision making.

Super-Pedicle Osteotomy for Correction of Focal Thoracolumbar Kyphosis

Focal thoracolumbar kyphotic deformities require operative correction through osteotomies to restore normal spinal balance. Traditional osteotomies, such as the pedicle subtraction osteotomy, that are often used in the lumbar spine are less useful in the thoracolumbar region. The super-pedicle osteotomy is a pedicle-sparing wedge osteotomy that can be used for correction of kyphosis in patients with thoracolumbar deformities. A retrospective review was conducted of 9 consecutive cases using the super-pedicle technique. Clinical data regarding patient age at presentation, etiology of deformity, symptoms, neurological status at presentation, American Society of Anesthesiologists class, type of surgery performed, estimated blood loss during surgery, and complications up to last follow-up were recorded. The primary parameter of interest was the angle at the planned osteotomy site before and after correction. Nine patients with an average age of 64 years were included. All 9 patients had focal thoracic kyphosis either at T11-T12 or T12-L1. All patients underwent thoracolumbar operations with super-pedicle osteotomies at their main level of kyphosis. Estimated blood loss was 600 mL. Average correction at the osteotomy site as measured on preoperative and postoperative radiographs was 31°. At an average follow-up of 338 days, no patients experienced rod fracture, but 1 patient required extension of fusion for proximal junctional kyphosis. In this small series of patients with thoracolumbar kyphosis, the super-pedicle osteotomy technique was clinically useful. More robust examination is required to determine the safety, utility, and durability of this osteotomy technique.

Vegan diet reduces neutrophils, monocytes and platelets related to branched-chain amino acids - A randomized, controlled trial.

Vegan diet (VD) has improved inflammatory activity in patients with rheumatoid arthritis (RA) in several small controlled trials. The underlying mechanism remains widely unclear. We investigated the effect of a VD in comparison to a meat-rich diet (MD) on markers of inflammation (which have been shown to be relevant in patients with RA) in healthy volunteers. 53 healthy, omnivore subjects were randomized to a controlled VD (n=26) or MD (n=27) for 4 weeks following a pre-treatment phase of a one week controlled mixed diet. Primary parameters of interest were sialylation of immunoglobulins, percentage of regulatory T-cells and level of interleukin 10 (IL10). Usual care immune parameters used in patients with RA and amino acid serum levels as well as granulocytes and monocytes colony stimulating factor (GM-CSF) serum levels were secondary parameters. In the VD group, total leukocyte, neutrophil, monocyte and platelet counts decreased and after four weeks they were significantly lower compared to the MD group (ANCOVA: leukocytes p=0.003, neutrophils p=0.001, monocytes p=0.032, platelets p=0.004). Leukocytes, neutrophils, monocytes, and platelets correlated with each other and likewise conform with serum levels of branched-chain amino acids, which were significantly lower in the VD compared to the MD group. The primary parameters did not differ between the groups and BMI remained stable in the two groups. Four weeks of a controlled VD affected the number of neutrophils, monocytes and platelets but not the number or function of lymphocytes. The relation with branched-chain amino acids and GM-CSF suggests a mode of action via the mTOR signaling pathway. REGISTERED AT: http://www.drks.de (German Clinical Trial register) at DRKS00011963.

The Aemulus Project. III. Emulation of the Galaxy Correlation Function

Abstract Using the N-body simulations of the Aemulus Project, we construct an emulator for the nonlinear clustering of galaxies in real and redshift space. We construct our model of galaxy bias using the halo occupation framework, accounting for possible velocity bias. The model includes 15 parameters, including both cosmological and galaxy bias parameters. We demonstrate that our emulator achieves ∼1% precision at the scales of interest, 0.1 h −1 Mpc &lt; r &lt; 10 h −1 Mpc, and recovers the true cosmology when tested against independent simulations. Our primary parameters of interest are related to the growth rate of structure, f, and its degenerate combination, fσ 8. Using this emulator, we show that the constraining power on these parameters monotonically increases as smaller scales are included in the analysis, all the way down to 0.1 h −1 Mpc. For a BOSS-like survey, the constraints on fσ 8 from r &lt; 30 h −1 Mpc scales alone are nearly a factor of two tighter than those from the fiducial BOSS analysis of redshift-space clustering using perturbation theory at larger scales. The combination of real- and redshift-space clustering allows us to break the degeneracy between f and σ 8, yielding an 11% constraint on f alone for a BOSS-like analysis. The current Aemulus simulations limit this model to surveys of massive galaxies. Future simulations will allow this framework to be extended to all galaxy target types, including emission-line galaxies.

Multidisciplinary methodology for turbine overspeed analysis

ABSTRACTIn this paper, an integrated approach to turbine overspeed analysis is presented, taking into account the secondary air system dynamics and mechanical friction in a turbine assembly following an unlocated high-pressure shaft failure. The axial load acting on the rotating turbine assembly is a governing parameter in terms of overspeed protection since it governs the level of mechanical friction which acts against the turbine acceleration due to gas torque. The axial load is dependent on both the force coming from secondary air system cavities surrounding the disc and the force on the rotor blades. It is highly affected by secondary air system dynamics because rotor movement modifies the geometry of seals and flow paths within the network. As a result, the primary parameters of interest in this study are the axial load on the turbine rotor, the friction torque between rotating and static structures and the axial position of the rotor.Following an initial review of potential damage scenarios, several cases are run to establish the effect of each damage scenario and variable parameter within the model, with comparisons being made to a baseline case in which no interactions are modelled. This allows important aspects of the secondary air system to be identified in terms of overspeed prevention, as well as guidelines on design changes in current and future networks that will be beneficial for overspeed prevention.

Analyzing Effects of Directionality and Random Heights in Drone-Based mmWave Communication

Utilization of drones as aerial access points (AAPs) is a promising concept to enhance network coverage and area capacity promptly and on demand. The emerging millimeter-wave (mmWave) communication technology may in principle deliver higher data rates, thus, making the use of AAPs more effective. By extending the conventional (planar) stochastic geometry considerations, we construct a novel three-dimensional model for drone-based mmWave communication that captures the high directionality of transmissions as well as the random heights of the communicating entities. Choosing signal-to-interference ratio as our primary parameter of interest, we assess system performance with an emphasis on the impact of the “vertical” dimension in aerial mmWave connectivity. We also demonstrate that accurate performance assessment is only possible with simplified models for certain ranges of input parameters.

Infant Feeding Practices and Weight Gain in Toddlers Born Very Preterm: A Pilot Study

PurposeLong-term consequences of prematurity are a public health concern. A pattern of slow initial weight gain followed by a period of rapid weight gain has been associated with poor cardiometabolic health outcomes. The purpose of this study was to examine the relationships between infant feeding practices and weight gain in a sample of 18-to-24-month olds corrected age born very preterm. Design and MethodsA cross-sectional design was used to examine the relationships between infant feeding practices and weight gain. Estimates of effect sizes and model fit estimates were the primary parameters of interest. ResultsMost of the participants received human milk after birth, but most had transitioned to formula before three months. Slightly less than half received complementary foods prior to four months corrected age. Gains in weight and head circumference were rapid after discharge from the neonatal intensive care unit, while gains in length lagged behind. Infant feeding practices did not have a clinically meaningful effect on weight gain. ConclusionsWhile the initiation of human milk feedings was encouraging, the duration fell short of recommendations. Practices such as the early introduction of complementary feedings and the addition of rice cereal to the bottle are troubling. Additionally, the rapid increase in weight gain may have a negative impact on future cardiometabolic health.Practice Implications.Clinical recommendations include ensuring support for the use of human milk before and after hospital discharge, close monitoring of physical growth, and ensuring adherence to the guidelines for the introduction of complementary foods.

Commentary: Can a Quasi-experimental Design Be a Better Idea than an Experimental One?

Commentary: Can a Quasi-experimental Design Be a Better Idea than an Experimental One?

Efficacy of homecare regimens for mechanical plaque removal in managing gingivitis a meta review.

Based on evidence as presented in systematic reviews what is the efficacy and safety of available homecare toothbrush regimens for mechanical plaque removal on plaque and gingivitis in adults? Three Internet sources were used (up to and including August 2014) to search for appropriate papers that satisfied the study purpose. Plaque scores and gingivitis scores were considered to be the primary parameter of interest. Safety was considered an important facet in relation to efficacy. Data and conclusions as presented in the selected papers were extracted. The potential risk of bias was estimated and the emerging evidence was graded. Independent screening of 176 unique reviews resulted in 10 published and eligible systematic reviews. They were categorized into one review evaluating the effect of an oral hygiene instruction with a toothbrush on plaque and gingivitis scores, five evaluating the efficacy of manual and power toothbrushes and three reviews evaluating toothbrush safety and one evaluating toothbrush contamination. Tooth brushing is effective in reducing levels of dental plaque. With respect to gingivitis power toothbrushes have a benefit over manual toothbrushes. The greatest body of evidence was available for oscillating-rotating brushes. Tooth brushing generally can be considered safe for the teeth and their investing tissues.

Efficacy of inter-dental mechanical plaque control in managing gingivitis--a meta-review.

What is the effect of mechanical inter-dental plaque removal in addition to toothbrushing, on managing gingivitis using various formats of inter-dental self-care in adults based on evidence gathered from existing systematic reviews? Three Internet sources were searched by a strategy designed to include systematic reviews on inter-dental cleaning devices. Plaque and gingivitis scores were the primary parameters of interest. Characteristics of selected papers were extracted. The potential risk of bias was estimated and the acquired evidence was graded. Screening of 395 papers resulted in six systematic reviews. Two papers evaluated the efficacy of dental floss, two of inter-dental brushes (IDB), one of woodsticks and one of the oral irrigator. Weak evidence of unclear or small magnitude was retrieved that supported dental floss, woodsticks and the oral irrigator to reduce gingivitis in addition to toothbrushing. No concomitant evidence for an effect on plaque emerged. There is moderate evidence that IDBs in combination with toothbrushing reduce both plaque and gingivitis. Evidence suggests that inter-dental cleaning with IDBs is the most effective method for inter-dental plaque removal. The majority of available studies fail to demonstrate that flossing is generally effective in plaque removal. All investigated devices for inter-dental self-care seem to support the management of gingivitis, however, to a varying extend.

MP83-02 COMBINATION OF MULTI-PARAMETRIC MAGNETIC RESONANCE IMAGING (MP-MRI) AND TRANSPERINEAL TEMPLATE-GUIDED MAPPING BIOPSY (TTMB) OF THE PROSTATE TO IDENTIFY CANDIDATES FOR HEMI-ABLATIVE FOCAL THERAPY

You have accessJournal of UrologyProstate Cancer: Localized IX1 Apr 2015MP83-02 COMBINATION OF MULTI-PARAMETRIC MAGNETIC RESONANCE IMAGING (MP-MRI) AND TRANSPERINEAL TEMPLATE-GUIDED MAPPING BIOPSY (TTMB) OF THE PROSTATE TO IDENTIFY CANDIDATES FOR HEMI-ABLATIVE FOCAL THERAPY Minh Tran, James Thompson, Maret Boehm, Marley Pulbrook, Daniel Moses, Ron Shnier, Phillip Brenner, Warick Delprado, Anne-Maree Haynes, Richard Savdie, and Phillip Stricker Minh TranMinh Tran More articles by this author , James ThompsonJames Thompson More articles by this author , Maret BoehmMaret Boehm More articles by this author , Marley PulbrookMarley Pulbrook More articles by this author , Daniel MosesDaniel Moses More articles by this author , Ron ShnierRon Shnier More articles by this author , Phillip BrennerPhillip Brenner More articles by this author , Warick DelpradoWarick Delprado More articles by this author , Anne-Maree HaynesAnne-Maree Haynes More articles by this author , Richard SavdieRichard Savdie More articles by this author , and Phillip StrickerPhillip Stricker More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1877AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Focal therapy (FT) is an emerging treatment option for patients with localized prostate cancer (PCa) aiming to reduce the morbidity of whole-gland therapy. Successful patient selection requires accurate identification and localization of clinically significant lesions within the prostate. Transperineal mapping biopsy (TTMB) is considered the gold standard diagnostic tool to identify candidates for FT. Multi-parametric magnetic resonance imaging (mp-MRI) has recently been shown to have a high NPV in detecting clinically significant PCa. We evaluated the accuracy of combined mp-MRI and TTMB for identifying lobes with significant cancer for application of hemi-ablative FT. METHODS From January 2012–January 2014, 89 consecutive patients aged ≥40 with PSA ≤15 underwent in sequential order: mp-MRI, TTMB and radical prostatectomy (RP) at a single centre. Analysis was performed on 50 patients that met consensus guidelines for FT (clinical stage ≤T2a, Gleason ≤3+4 and no evidence of extracapsular extension or seminal vesicle invasion on mp-MRI or TTMB). Lobes were stratified into lobes with significant cancer (LSC), insignificant cancer (LIC) and no cancer (LNC). Using histopathology at RP, the predictive performance of combined mp-MRI and TTMB in identifying LSC was evaluated. RESULTS The sensitivity, specificity and PPV for combined mp-MRI+TTMB for LSC was 97%, 64% and 84% respectively. Due to the risk of undertreating significant lesions, NPV was considered the primary parameter of interest. The NPV for combined mp-MRI+TTMB for LSC was 91%. Of the 50 patients, 22 had significant unilateral disease on mp-MRI+TTMB and were thus potential candidates for hemi-ablative FT. Two (91%) of the 22 patients had a significant lesion crossing the sagittal midline with contralateral extension of 4mm and 6mm respectively. One of these two patients additionally had a separate small but moderate risk lesion (<0.1cc Gleason 3+4 with 10% Gleason pattern 4) undetected by mp-MRI+TTMB. CONCLUSIONS In candidates for focal therapy based on consensus guidelines, mp-MRI reported by expert radiologists and TTMB provide an excellent negative predictive value in the application for hemi-ablative focal therapy. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e1050 Peer Review Report Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Minh Tran More articles by this author James Thompson More articles by this author Maret Boehm More articles by this author Marley Pulbrook More articles by this author Daniel Moses More articles by this author Ron Shnier More articles by this author Phillip Brenner More articles by this author Warick Delprado More articles by this author Anne-Maree Haynes More articles by this author Richard Savdie More articles by this author Phillip Stricker More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Proposed Method for Probabilistic Estimation of Peak Component Acceleration Demands

A probabilistic method is proposed to quantify peak component acceleration (PCA) demands for nonstructural components attached to elastic and inelastic structures. Incremental dynamic analyses and site-specific ground-motion hazard information are used to estimate PCA hazard curves and component uniform hazard spectra (CUHS) based on various structural and nonstructural parameters. For a given structural system, the primary parameters of interest are the location of the component within the structure, the ratio of the period of the component to the modal periods of the primary structure, and the component damping ratio. Representative results for shear wall structures illustrate the value of applying the method to acceleration-sensitive components, as the quantification of CUHS facilitates the implementation of performance-based design and evaluation approaches. The variability in the component responses presented highlights the need for a robust probabilistic seismic demand estimation methodology for nonstructural components in which the major sources of variability are incorporated.

Development of a Lightweight Low-Carbon Footprint Concrete Containing Recycled Waste Materials

Use of any recycled material helps to maintain a greener environment by keeping waste materials out of the landfills. Recycling practices also can decrease the environmental and economical impact of manufacturing the materials from virgin resources, which reduces the overall carbon footprint of industrial materials and processes. This study examined the use of waste materials such as crushed glass, ground tire rubber, and recycled aggregate in concrete. Compressive strength and elastic modulus were the primary parameters of interest. Results demonstrated that ground tire rubber introduced significant amounts of air into the mix and adversely affected the strength. The introduction of a defoamer was able to successfully remove part of the excess air from the mix, but the proportional strength improvements were not noted implying that air left in the defoamed mixture had undesirable characteristics. Freeze-thaw tests were next performed to understand the nature of air in the defoamed mixtures, and results demonstrated that this air is not helpful in resisting freeze-thaw resistance either. Overall, while lightweight, low-carbon footprint concrete materials seem possible from recycled materials, significant further optimization remains possible.

Inference on the Primary Parameter of Interest with the Aid of Dimension Reduction Estimation

Summary As high dimensional data become routinely available in applied sciences, sufficient dimension reduction has been widely employed and its research has received considerable attention. However, with the majority of sufficient dimension reduction methodology focusing on the dimension reduction step, complete analysis and inference after dimension reduction have yet to receive much attention. We couple the strategy of sufficient dimension reduction with a flexible semiparametric model. We concentrate on inference with respect to the primary variables of interest, and we employ sufficient dimension reduction to bring down the dimension of the regression effectively. Extensive simulations demonstrate the efficacy of the method proposed, and a real data analysis is presented for illustration.

Identification of Process Parameters for Friction Stir Welding Ti–6Al–4V

An experimental study was conducted to identify acceptable welding parameters for friction stir welding Ti-6Al-4V butt joints, ranging from 3 mm to 12 mm in thickness. The primary parameters of interest were the spindle speed and feed rate. Welds were produced using spindle speeds of 140–320 rpm and feed rates between 40 mm/min and 125 mm/min. Joints were evaluated by macro- and micrometallurgical examination along with limited fatigue and tensile testing. The weld parameters were found to influence the microstructure, penetration, void formation, and tool wear among other things. A process window was identified for combinations of the feed rate and spindle speed capable of achieving defect free joints for a given tooling configuration and thickness. It was found that the tensile and fatigue properties of the welds produced in this study were comparable to Ti–6Al–4V base material properties.