Fractional Hamiltonian analysis of higher order derivatives systems

The fractional Hamiltonian analysis of 1+1 dimensional field theory is investigated and the fractional Ostrogradski's formulation is obtained. The fractional path integral of both simple harmonic oscillator with an acceleration-squares part and a damped oscillator are analyzed. The classical results are obtained when fractional derivatives are replaced with the integer order derivatives.Comment: 13 page

How Can Recessions Be Brought To An End? Effects Of Macroeconomic Policy Actions On Durations Of Recessions

This paper analyzes how effective macroeconomic policy actions are in ending recessions. We also investigate which structural factors help the country to experience shorter recessions. We implement survival regression analysis and conclude that expansionary monetary policy significantly decreases durations of recessions whereas fixing the exchange rate does not have an effect on the durations of recessions. Expansionary fiscal policy has undesired effects and decreases the probability that recession will end, thus increasing the durations of recessions. The analysis of country specific factors indicates that emerging countries experience shorter recessions. Recessions in countries with higher trade openness last significantly longer. Financial openness and institutional quality do not have significant effects of recession durations. The empirical analysis takes into account alternative probability distributions and endogeneity of policy actions

Nonlinear modeling of an immersed transmitting capacitive micromachined ultrasonic transducer for harmonic balance analysis.

Finite element method (FEM) is used for transient dynamic analysis of capacitive micromachined ultrasonic transducers (CMUT) and is particularly useful when the membranes are driven in the nonlinear regime. One major disadvantage of FEM is the excessive time required for simulation. Harmonic balance (HB) analysis, on the other hand, provides an accurate estimate of the steady-state response of nonlinear circuits very quickly. It is common to use Mason's equivalent circuit to model the mechanical section of CMUT. However, it is not appropriate to terminate Mason's mechanical LC section by a rigid piston's radiation impedance, especially for an immersed CMUT. We studied the membrane behavior using a transient FEM analysis and found out that for a wide range of harmonics around the series resonance, the membrane displacement can be modeled as a clamped radiator. We considered the root mean square of the velocity distribution on the membrane surface as the circuit variable rather than the average velocity. With this definition, the kinetic energy of the membrane mass is the same as that in the model. We derived the force and current equations for a clamped radiator and implemented them using a commercial HB simulator. We observed much better agreement between FEM and the proposed equivalent model, compared with the conventional model

Thermoelectric power of nondegenerate Kane semiconductors under the conditions of mutual electron-phonon drag in a high electric field

The thermoelectric power of nondegenerate Kane semiconductors with due regard for the electron and phonon heating, and their thermal and mutual drags is investigated. The electron spectrum is taken in the Kane two-band form. It is shown that the nonparabolicity of electron spectrum significantly influences the magnitude of the thermoelectric power and leads to a change of its sign and dependence on the heating electric field. The field dependence of the thermoelectric power is determined analytically under various drag conditions.Comment: 25 pages, RevTex formatted, 3 table

Carotid endarterectomy compared with carotid artery stenting for extracranial carotid artery stenosis: a retrospective single-centre study

Aim: One of the main risk factors for an ischemic stroke is significant carotid artery stenosis, and extracranial severe carotid artery stenosis accounts for 20% of ischemic strokes. Prior to the development of carotid artery stenting (CAS), the only effective and reliable treatment for carotid artery stenosis was carotid endarterectomy (CEA). This study compares the results of CAS and CEA in patients with significant carotid artery stenosis. Methods: Between 2018 and 2022, hospital records of all patients who underwent carotid artery revascularization at the institution were retrospectively analyzed. Patients were divided into two groups depending on whether CEA or CAS was performed for carotid revascularization. Propensity score matching was performed to reduce bias by equating the baseline clinical characteristics of the groups. To compare 30-day, 1-year, and long-term outcomes, rates of transient ischemic attack (TIA), myocardial infarction, stroke, all-cause mortality, and composite endpoints were analyzed. Results: After PSM, 76 patients each in the CEA and CAS groups were compared. The mean age was 69.80 years ± 11.35 years and 121 (80%) were male. The patients were followed up for a mean of 33 months ± 6 months. The incidence of TIA in the perioperative period [9 (12%) vs. 4 (5%); P < 0.05], TIA and composite endpoint at 1-year period [11 (15%) vs. 2 (3%); P < 0.05 and 27 (36%) vs. 16 (21%); P < 0.05, respectively] were significantly higher in the CAS group than in the CEA group. No difference was observed between the groups in the long-term. Conclusions: There was no noticeable difference between the CEA and CAS groups in the examination of cases with severe carotid artery stenosis in terms of 1-month, and 1-year results (apart from TIA and composite endpoints), or long-term outcomes. Extracranial carotid artery stenosis can be treated safely and effectively also by CAS

Co-firing of biomass with coals Part 1. Thermogravimetric kinetic analysis of combustion of fir (abies bornmulleriana) wood

The chemical composition and reactivity of fir (Abies bornmulleriana) wood under non-isothermal thermogravimetric (TG) conditions were studied. Oxidation of the wood sample at temperatures near 600 A degrees C caused the loss of aliphatics from the structure of the wood and created a char heavily containing C-O functionalities and of highly aromatic character. On-line FTIR recordings of the combustion of wood indicated the oxidation of carbonaceous and hydrogen content of the wood and release of some hydrocarbons due to pyrolysis reactions that occurred during combustion of the wood. TG analysis was used to study combustion of fir wood. Non-isothermal TG data were used to evaluate the kinetics of the combustion of this carbonaceous material. The article reports application of Ozawa-Flynn-Wall model to deal with non-isothermal TG data for the evaluation of the activation energy corresponding to the combustion of the fir wood. The average activation energy related to fir wood combustion was 128.9 kJ/mol, and the average reaction order for the combustion of wood was calculated as 0.30

Stability of the monoclinic phase in the ferroelectric perovskite PbZr(1-x)TixO3

Recent structural studies of ferroelectric PbZr(1-x)TixO3 (PZT) with x= 0.48, have revealed a new monoclinic phase in the vicinity of the morphotropic phase boundary (MPB), previously regarded as the the boundary separating the rhombohedral and tetragonal regions of the PZT phase diagram. In the present paper, the stability region of all three phases has been established from high resolution synchrotron x-ray powder diffraction measurements on a series of highly homogeneous samples with 0.42 <=x<= 0.52. At 20K the monoclinic phase is stable in the range 0.46 <=x<= 0.51, and this range narrows as the temperature is increased. A first-order phase transition from tetragonal to rhombohedral symmetry is observed only for x= 0.45. The MPB, therefore, corresponds not to the tetragonal-rhombohedral phase boundary, but instead to the boundary between the tetragonal and monoclinic phases for 0.46 <=x<= 0.51. This result provides important insight into the close relationship between the monoclinic phase and the striking piezoelectric properties of PZT; in particular, investigations of poled samples have shown that the monoclinic distortion is the origin of the unusually high piezoelectric response of PZT.Comment: REVTeX file, 7 figures embedde

Biogeosciences perspectives on integrated, coordinated, open, networked (ICON) science

This article is composed of three independent commentaries about the state of ICON principles (Goldman et al. 2021) in the AGU Biogeosciences section and discussion on the opportunities and challenges of adopting them. Each commentary focuses on a different topic: Global collaboration, technology transfer and application (Section 2), Community engagement, citizen science, education, and stakeholder involvement (Section 3), and Field, experimental, remote sensing, and real-time data research and application (Section 4). We discuss needs and strategies for implementing ICON and outline short- and long-term goals. The inclusion of global data and international community engagement are key to tackle grand challenges in biogeosciences. Although recent technological advances and growing open-access information across the world have enabled global collaborations to some extent, several barriers ranging from technical to organizational to cultural have remained in advancing interoperability and tangible scientific progress in biogeosciences. Overcoming these hurdles is necessary to address pressing large-scale research questions and applications in the biogeosciences, where ICON principles are essential. Here, we list several opportunities for ICON, including coordinated experimentation and field observations across global sites, that are ripe for implementation in biogeosciences as a means to scientific advancements and social progress