Impulse Values Research Articles

Positive solutions of impulsive time-scale boundary value problems with p-Laplacian on the half-line

In this paper, four functionals fixed point theorem is used to investigate the existence of positive solutions for second-order time-scale boundary value problem of impulsive dynamic equations on the half-line.

Positive solutions for multi point impulsive boundary value problems on time scales

Positive solutions for multi point impulsive boundary value problems on time scales

Sign-constancy of Green's functions for two-point impulsive boundary value problems

Sign-constancy of Green's functions for two-point impulsive boundary value problems

Recovery Slope of Heart Rate Variability as an Indicator of Internal Training Load

The way in which the Root Mean Square of the Successive Differences between adjacent RR intervals (RMSSD) recovers immediately after exercise could be a good indicator of internal training load (ITL). The aim of this study is to design a recovery index based on RMSSD. Forteen healthy men took part in this study. The experiment lasted 2 weeks, with 4 separate (48 - 72 h) sessions. First session was an incremental treadmill test to determine ventilatory thresholds (VT1 and VT2) and maximal aerobic speed (MAS). Each subject ran at VT1 speed (second day), VT2 speed (third day) and a time-to-exhaustion test at MAS (fourth day). The duration of VT1 and VT2 loads was selected in such a way that the product intensity-duration (training load) was the same. HRV was measured from 10’ prior to test (Rest) to 30’ after completed (Recovery). Recovery slopes were calculated from RMSSD values at 10 and 30 minutes. Borg scale was recorded at the end of every test and the Training Impulse (TRIMP) values were calculated using Banister equations. The RMSSD values dropped substantially regardless of the intensity and the duration of exercise (average 4 ms). The RMSSD recovery was linear during the 30 min and different depending on the intensity of exercise. To propose a recovery index, we calculated the slope of RMSDD over the 30 minutes (slope-30) and also the first 10 minutes (slope-10). Given that the slopes presented an exponential behavior in relation with effort intensity, three curves were obtained (average values, plus SD and minus SD) defining a nomogram. For practical application, we propose: 1) to measure RMSSD the last 5 minutes of exercise and any period of 5 minutes during the first 30 minutes recovery; 2) to calculate the slope of RMSSD between exercise and recovery; 3) to compare with the nomogram.

Impact of fume particles in the keyhole vapour

During laser material processing, the energy of the laser beam needs to be efficiently and constantly transported to the processing zone to guarantee constant processing. However, spatters or ejected particles from the keyhole can absorb and scatter the laser energy leading to inhomogeneous heat input and can initiate defect occurrence like pore formation. The impact of ejected particles from the keyhole on the energy transport of the laser beam is not completely understood since they are difficult to observe due to the small size and high speeds of the ejections. In this work, the particle characteristics were derived from a simulation of the keyhole wall movement. The behavior of the calculated particles in a side shielding gas jet was calculated to derive the height, at which the particles leave the laser beam and are not interrupting the laser energy transfer to the processing zone. Low impulse values of the particles were calculated e.g., at defocusing positions slightly underneath the material surface, where also highest melt pool sizes were found. These observations indicate that the fume particles can be one reason to limit the energy delivery. An efficiency increase can be achieved by adjusting the keyhole parameters to a more stable keyhole.

The neural basis underlying procrastination: a large-scale study of brain networks

Procrastination is a type of irrational behavior during which an individual voluntarily delays the execution of a task despite perceiving such behavior as harmful. Procrastination adversely affects people’s emotions, academic performances, and social achievements; it reduces their subjective well-being, and worse, their physical and mental health. The brain systems that regulate procrastination are still largely undetermined; previous studies have only explored the relationships between procrastination and regional brain activities and cerebral functional connections. Because procrastination involves complex psychological motivations that are dependent on elements such as task value representation, cognitive control, and the approach-avoidance conflict, some limitations to exploring the neural basis of procrastination using univariate and regional brain activities may exist. Therefore, this study used graph-theoretic analysis to investigate the connectivity patterns of large-scale brain networks underlying procrastination. We first defined the 264 regions of interest (ROIs) introduced by Power et al. (2011) as nodes of the network, and then reconstructed the ten intrinsic large-scale brain networks using graph-theoretic analysis. The results showed that the constructed brain network had better network topology attributes, such as a higher local and global efficiency. The strength of functional connectivity within each of these ten brain networks and that between them was then calculated using Pearson’s correlation. Finally, the association between procrastination and the functional network connectivity of brain networks was examined. We found that procrastination was negatively associated with the functional connectivity within the cingulo-opercular network (CON), whereas it was positively associated with the functional connectivity within the subcortical network (SCN). We also found a positive correlation between procrastination and the functional connectivity between the salience network (SAN) and the SCN. These results suggest that the functional network connectivity within the CON and the SCN, as well as that between the SAN and the SCN may be the neural basis underlying procrastination, which highlights the critical role of cognitive control and impulsive value representation in procrastination.

Value of Contrast-Enhanced Ultrasound and Acoustic Radiation Force Impulse Imaging for the Differential Diagnosis of Benign and Malignant Thyroid Nodules.

Objectives: To assess the value of contrast-enhanced ultrasound (CEUS) and acoustic radiation force impulse (ARFI) imaging for the differential diagnosis of benign and malignant thyroid nodules.Methods: CEUS was performed in eighty-eight thyroid nodules. The patterns of CEUS were analyzed, and ARFI was then performed. The shear wave velocities (SWVs) of the nodules and the surrounding normal thyroid tissue were obtained. The areas under the curve (AUCs) and cut-off value were obtained by a receiver operating characteristic (ROC) curve analysis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic rate of each modality were assessed and compared using pathological diagnosis.Results: Among 88 nodules, 29 nodules were malignant and 59 were benign. The sensitivity, specificity, PPV, NPV, and diagnostic rate of CEUS were 79.3, 91.5, 82.1, 90, and 87.5%, respectively. Using a cut-off value of 2.565 m/s for SWV, the sensitivity, specificity, PPV, NPV and diagnostic rate for malignancy were 75.9, 94.9, 88.0, 88.9, and 88.6%, respectively. The AUC was 0.878. The sensitivity, specificity, PPV, NPV and diagnostic rate of CEUS in combination with ARFI were 93.1, 89.8, 81.8, 96.3, and 90.9%, respectively.Conclusion: Both CEUS and ARFI are valuable for the differential diagnosis of benign and malignant thyroid nodules. Combining these two methods can improve the diagnostic rate.

Positive solutions to one-dimensional quasilinear impulsive indefinite boundary value problems

Consider the one-dimensional quasilinear impulsive boundary value problem involving the p-Laplace operator \t\t\t{−(ϕp(u′))′=λω(t)f(u),0<t<1,−Δu|t=tk=μIk(u(tk)),k=1,2,…,n,Δu′|t=tk=0,k=1,2,…,n,u′(0)=0,u(1)=∫01g(t)u(t)dt,\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ \\textstyle\\begin{cases} -(\\phi_{p}(u'))'=\\lambda \\omega (t)f(u), \\quad 0< t< 1, \\\\ -\\Delta u|_{t=t_{k}}=\\mu I_{k}(u(t_{k})), \\quad k=1,2,\\ldots,n, \\\\ \\Delta u'|_{t=t_{k}}=0, \\quad k=1,2,\\ldots,n, \\\\ u'(0)=0, \\qquad u(1)=\\int_{0}^{1}g(t)u(t)\\,dt, \\end{cases} $$\\end{document} where lambda, mu >0 are two positive parameters, phi_{p}(s) is the p-Laplace operator, i.e., phi_{p}(s)=|s|^{p-2}s, p>1, omega (t) changes sign on [0,1]. Several new results are obtained for the above quasilinear indefinite problem.

Positive solutions for singular impulsive Dirichlet boundary value problems

In this paper, a class of singular impulsive Dirichlet boundary value problems is considered. By using variational method and critical point theory, different parameter ranges are obtained to guarantee existence and multiplicity of positive classical solutions of the problem when nonlinearity exhibits different growths.

Prognostic value of impulsivity in treatment outcomes in patients with alcohol use and/or cocaine use disorder in a rehabilitation programme

IntroductionImpulsivity is linked to factors that are negatively correlated with drug and alcohol use. Individuals with substance use disorder (SUD) often suffer from cognitive deficits and, additionally, have high levels of impulsivity. Studies show that cognitive deficits are associated with lower self-efficacy (SE), and the latter is considered an important indicator of SUD management and treatment outcomes. The relationship between impulsivity and SE, however, remains unclear. This prospective study examined impulsivity as a prognostic indicator for SE in SUD populations admitted for inpatient treatment.MethodsFifty individuals, aged 18–61, with either a cocaine use and/or alcohol use disorder diagnosis were examined within 72 hours of (1) the start and (2) completion of treatment.ResultsImpulsivity was a significant predictor of SE. Duration of abstinence (in days), estimated intelligence, global assessment of functioning (GAF) and patient age explained 16% of the variance in the change in SE at discharge. After including impulsivity in the regression model, the total variance explained by the model was 28% (F [5.505] = 3.47, p = 0.01). Impulsivity explained an additional 12% of the variance after controlling for the above variables (R2 change = 0.12, F change [4.45] = 7.206, p = 0.01).ConclusionImpulsivity is a significant predictor of SE following an 8-week impatient treatment programme for individuals diagnosed with SUD. To our knowledge, this is the first study to demonstrate that impulsivity holds prognostic value in respect of the change in SE after inpatient treatment of individuals with SUD. Based on our findings, replication studies are warranted.

Diagnostic value of acoustic radiation force impulse for BI-RADS category 4 breast lesions of different sizes.

To determine the diagnostic value of combined conventional ultrasound (US) and acoustic radiation force impulse (ARFI) imaging for the differential diagnosis of BI-RADS category 4 breast lesions of different sizes. From April 2013 to January 2015, 283 patients (with a total of 292 breast lesions) who underwent US and ARFI examination were included in this retrospective study. The SWV for the lesion and adjacent normal breast tissue were measured and the SWV ratio was calculated. VTI grade was also assessed. The lesions were separated into three groups on the basis of size, and two combinations of ARFI parameters (SWV + VTI and SWV ratio + VTI) were applied to reassess the BI-RADS categories. Diagnoses were confirmed by pathological examination after biopsy or surgery. ROC analysis was performed to assess the diagnostic efficiency of each method. The Z test was used to compare the difference between AUC of the two methods. Significant improvement was seen in the diagnostic performance of US with the use of the ARFI parameters SWV + VTI (77/179 [43.0%] of BI-RADS category 4A breast lesions were downgraded) and SWV ratio + VTI (64/179 [35.8%] of BI-RADS category 4A breast lesions were downgraded, including two malignant cases that were misdiagnosed as benign) (P < 0.01). The difference between the performances of the two combinations-SWV + VTI and SWV ratio + VTI-was significant only in breast lesions <10 mm in size, where the AUC of SWV ratio + VTI was significantly greater than the AUC of SWV + VTI (0.929 vs. 0.874; P < 0.01). Combination of US with ARFI can improve diagnostic performance and help avoid unnecessary biopsy in BI-RADS category 4 breast lesions. The combination of SWV ratio + VTI can improve BI-RADS classification of small lesions (<10 mm size).

Pediatric Fontan associated liver disease: Non-invasive evaluation with serologic markers and acoustic radiation force impulse (ARFI) elastography

Hepatic fibrosis is a significant complication in adult Fontan patients suggesting development as a function of time since the surgery. Children with Fontan circulation are not routinely assessed for development of liver disease. We aimed to evaluate the effectiveness of serologic biomarkers and acoustic radiation force impulse (ARFI) elastography to detect liver disease in pediatric Fontan patients. Patients ≥1 year after Fontan operation prospectively had hepatic US with acoustic radiation force impulse and laboratory testing. Clinical cardiac data (echocardiograms, cardiac catheterizations) were reviewed. Statistical analysis was performed using Pearson's correlation coefficient, Wilcoxon rank-sum test and Kruskal-Wallis test. Forty patients were enrolled with median age of 11 years and median time since Fontan of 6.5 years. Platelet count negatively correlated with years since Fontan (p < 0.000). Thrombocytopenia was noted in 15% of patients with the lowest platelet count of 78 K/cu mm, in a patient >10 years from the Fontan (DORV) operation. Alanine transaminase (ALT, p = 0.034) and aspartate aminotransferase (AST, p = 0.009) were higher in patients with Extracardiac Conduit Fontan compared to those with Extracardiac Pericardial and Lateral Fontan operations. Heterogeneous echotexture on liver ultrasound correlated with years since Fontan (p = 0.022), however all acoustic radiation force impulse values were elevated (>1.34 m/s) and did not correlate with age, years since Fontan, labs or imaging. FibroSure values did not correlate with years since Fontan. This suggests that ARFI may be elevated due to passive hepatic congestion, limiting its value in this patient population. Additional testing is necessary to identify reliable non-invasive screening modalities for hepatic fibrosis in Fontan patients. Our study is the largest pediatric study to evaluate ARFI in patients after the Fontan operation and showed increased shear wave speed for all patients with no correlation with time since palliation. Decreasing platelet count may indicate the development of liver fibrosis.

Diagnostic value of acustic radiation force impulse imaging in the assessment of salivary gland involvement in primary Sjögren's sydrome.

The aim of this study is to investigate the diagnostic value of Acoustic Radiation Force Impulse (ARFI) imagingin the assessment of salivary gland involvement in primary Sjögren's syndrome (pSS). Twenty fivepatients with pSS and 25 healthy volunteers were included. First, echostructures and the thickness of the submandibular andparotid glands were evaluated by B-mode ultrasonography. Then, ARFI imaging with Virtual Touch Quantification® wasperformed. Ten independent shear wave velocity measurements were taken from each gland. Finally, the mean shear wavevelocity (SWV) values were calculated, and used for further analysis. The mean SWV values of parotid and submandibularglands were significantly higher in the pSS patients than in the healthy control group (p<0.001). The cut-off of SWVvalues were calculated to be 1.98 m/s for submandibular glands, and 1.93 m/s for parotid glands. In pSS patients, the meanSWV values of parotid glands were higher than those of the submandibular glands (p<0.001) and no statistically significantrelationships between symptom duration or the degree of xerostomia and mean SWV values of parotid and submandibularglands were found (all p>0.005). Our findings indicate that ARFI imaging may provide a non-invasive, simpleand fast means of assessment of glandular impairment as an alternative test when other salivary gland tests are inconclusive orcannot be performed. ARFI may be a valuable adjunct for the clinical diagnosis of pSS.

A density functional study on some cyclic N10 isomers

Abstract Polynitrogen compounds, comprising only nitrogen atoms, are rare. They are considered as promising candidates of clean (green) high energy density materials because of their high energy content and their sole decomposition product is N2. Extending the previous work which was on cyclic N8 isomers, in this study some cyclic N10 isomers having 1–4 cycles are considered within the limitations of density functional theory at the levels of B3LYP/6-311++G(d,p) and B3LYP/cc-PVTZ. Some of the structures, including the monocyclic one, decompose by eliminating certain number of N2 units while some remain intact. All the stable isomers (1–3, 6–8) investigated presently are highly endothermic that they are candidates for clean high energy materials. Certain quantum chemical properties, IR and UV-VIS spectra as well as the specific impulse values for the stable structures are reported.

Predictive value for esophageal varices using acoustic radiation force impulse elastography in post-hepatitis B cirrhosis patients

Objective: A retrospective analysis of the predictive value of acoustic radiation force impulse (ARFI) elastography for esophageal varices in post-hepatitis B cirrhosis patients. Methods: 124 patients with post-hepatitis B cirrhosis who were admitted to Tianjin Second People's Hospital from August 2016 to August 2017 were selected. According to the shape of esophageal varices under gastroscopy and the risk of bleeding, patients were divided into 4 groups, none, mild, moderate and severe. In ARFI mode, the VTQ function was used to detect the VTQ values of the liver and spleen. The receiver operating characteristic curve and area under the curve (AUC) were used to evaluate the diagnosis of esophageal varices by VTQ values of the liver and spleen. Analysis of variance was performed on the data between the groups, and χ (2) test was performed for categorical data. Results: The difference in liver VTQ values between groups were statistically significant (F = 12.623, P < 0.01). There was a statistically significant difference in VTQ values between spleens (F = 9.022, P < 0.01). The liver VTQ predicts that the AUC value of mild esophageal varices in patients with cirrhosis was 0.701 (0.575-0.827); moderate varices was 0.802 (0.701-0.902); severe varices was 0.885 (0.784-0.986). The best cutoff value was 2.235, the specificity was 97.37%, the negative predictive value was 88.10%, and the accuracy was 90.16%. The VTQ value of spleen predicts the AUC value of mild esophageal varices in patients with liver cirrhosis was 0.688 (0.539-0.798); moderate varices were 0.762 (0.651-0.873); severe varices were 0.800 (0.671-0.928). The best cutoff value was 2.885, the specificity was 84.21%, and the negative predictive value was 82.05%. Conclusion: The application of ARFI elastography in the determination of VTQ values of liver and spleen has certain predictive value for esophageal varices and it might be useful for primary screening of esophageal varices in post-hepatitis B cirrhosis patients.

Scattering Theory of Impulsive Sturm–Liouville Equation in Quantum Calculus

We consider an impulsive boundary value problem consisting of a quantum difference equation and impulsive boundary conditions. Discussing the Jost solution and scattering function of this problem, we study the properties of scattering function and relations between scattering solutions. Besides, we present an example that informs us about the eigenvalues of a special case of this problem.

Bis(imidazolyl)-BH2 ]+ [Bis(triazolyl)-BH2 ]- Ionic Liquids with High Density and Energy Capacity.

[Bis(imidazolyl)-BH2 ]+ [bis(triazolyl)-BH2 ]- and [bis(imidazolyl)-BH2 ]+ [tris(triazolyl)-BH]- were synthesized, the cations and anions of which were functionalized with B-H groups and azoles. As B-H groups contribute to the hypergolic activity and azole groups improve the energy output, the resulting ionic liquids exhibited ignition delay times as low as 20 ms and energy outputs as high as 461.1 kJ mol-1 . In addition, densities (1.07-1.22 g cm-3 ) and density-specific impulse (≈360 s g cm-3 ) values reached a relatively high level. These ionic liquids show great promise as sustainable rocket fuels.

Efficacy of the Sonoelastography Method for Diagnosis of Fibrosis in Renal Transplant Patients.

Although biopsy is the most important method for diagnosing the cause of renal allograft dysfunction, sonoelastography, a new ultrasonography method, can be used to distinguish between the soft or hard nature of lesions. In this study, our aim was to investigate whether sonoelastography could diagnose fibrosis in renal transplant patients. In this prospective study, we included patients over 18 years old who were recommended for clinical biopsy. Sonoelastographic evaluation was made by conducting acoustic radiation force impulse measurements for each patient after they were admitted to the clinic for biopsy. Measurements were performed just before the biopsy procedure. All results were examined by 2 experienced radiologists using the Siemens S3000 Ultrasound Machine (Erlangen, Germany). Comparisons of ultrasonographic values with biopsy results were made with SPSS software (SPSS: An IBM Company, version 20, IBM Corporation, Armonk, NY, USA). Of the 65 patients included in this study, pathology showed acute T-cell-mediated rejection in 37 patients. There was a significant correlation between the pathologic Banff scores and the sonographic acoustic radiation force impulse values (P = .002), where the degree of Banff increased as the mean acoustic radiation force impulse values elevated. A rise in mean impulse values correlated with increased degree of interstitial fibrosis in renal allografts. Renal parenchymal echogenicity of patients significantly differed by sex (P = .009), with an average renal echogenicity of grade 1 in women and grade 0 in men. Also, a statistically significant difference was found between age of the renal transplant recipient and resistive index values. Our study showed a significant correlation between Banff degree and the acoustic radiation force impulse values of renal transplant patients. In addition to biopsy, sonoelastography can be beneficial for the diagnosis of fibrosis in renal transplant patients.

A Reliable Method for Predicting the Specific Impulse of Chemical Propellants

The specific impulse (Isp) is an important performance parameter that describes energy efficiency of propellant combustion and is intimately related to the rocket engine thrust. In this study, it was possible by using only two variables, i.e., the heat of reaction (Q) and the number of moles of gaseous reaction products per gram of propellant (Ng) calculated according to [H2O-CO2] arbitrary decomposition assumption and constants derived from the ISPBKW code to predict the specific impulse of more than 165 compositions belonging to virtually all classes of propellants such as monopropellants, single-base, double-base, triple-base, and cast modified double-base (CMDB) propellants, pseudo-propellants, composite propellants, liquid mono- and bipropellants, and finally hybrid propellants. Further analysis reveals that for C-H-N-O containing propellants, the specific impulse values estimated using the new method should not deviate more than 5% from the output of the ISPBKW thermochemical code.

Impulsivity predicts illness severity in long-term course of bipolar disorder: A prospective approach.

Bipolar disorder is a common, severe and chronic mental illness. Despite this, predictors of illness severity remain poorly understood. Impulsivity is reported to be associated with bipolar disorder and aggravating comorbidities. This study therefore sought to examine the predictive value of impulsivity for determining illness severity in euthymic bipolar disorder patients. Baseline trait impulsivity of 120 bipolar euthymic patients (81 bipolar disorder I [68%], 80 female [67%]) and 51 healthy controls was assessed using Barratt Impulsiveness Scale 11. The impact of impulsivity on illness severity (measured with morbidity index) was prospectively tested in 97 patients with sufficient follow-up data (average observation time: 54.4 weeks), using linear regression analysis. Barratt Impulsiveness Scale 11 total (β = 0.01; p < 0.01) and in particular Barratt Impulsiveness Scale 11 attentional subscale scores (β = 0.04; p < 0.001) predicted illness severity in bipolar disorder, while controlling for other clinical variables. Only age at onset persisted as an additional, but less influential predictor. Barratt Impulsiveness Scale 11 total scores and Barratt Impulsiveness Scale 11 attentional subscale scores were significantly higher in euthymic patients compared to controls. This was not observed for the motor or non-planning subscale scores. The average year-long observation time might not be long enough to account for the chronic course of bipolar disorder. Trait impulsivity and particularly attentional impulsivity in euthymic bipolar patients can be strong predictors of illness severity in bipolar disorder. Future studies should explore impulsivity as a risk assessment for morbidity and as a therapeutic target in bipolar disorder patients.