A numerical study on free vibration analysis of detailed and homogenized models for FG-CNTRC beams

The goal of this study is to compare and investigate the free vibration characteristics of detailed and homogenized models for functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams, based on the finite element method (FEM). In this study, three types of FG-CNTRC beams and boundary conditions are considered for different volume fractions of CNT: UD (uniformly distributed), FG-X, and FG-Λ beams. These beams in which single-walled carbon nanotubes (SWCNTs) are distributed with a gradient through the thickness are employed and analyzed for simply supported (SS), clamped-clamped (CC), and free-free (FF) boundary conditions. For the homogenized model, the effective material properties are determined in terms of the CNT volume fraction using the linear rule of mixture. A commercial midas NFX program is used for finite element simulations to analyze the free vibration responses of FG-CNTRC beams. The numerical results are compared with the existing analytical solutions in the literature in order to validate the developed finite element models

Numerical Optimization of CNT Distribution in Functionally Graded CNT-Reinforced Composite Beams

This paper is concerned with the numerical optimization of the thickness-wise CNT (carbon nanotube) distribution in functionally graded CNT-reinforced composite (FG-CNTRC) beams to secure the structural safety. The FG-CNTRC in which CNTs are inserted according to the specific thickness-wise distribution pattern are extensively investigated for high-performance engineering applications. The mechanical behaviors of FG-CNTRC structures are definitely affected by the distribution pattern of CNTs through the thickness. Hence, the tailoring of suitable CNT distribution pattern is an essential subject in the design of FG-CNTRC structure for a given boundary and loading conditions. Nevertheless, the thickness-wise CNT distribution pattern has been assumed by several linear functions so that these assumed primitive patterns cannot appropriately respond to arbitrary loading and boundary conditions. In this context, this paper aims to introduce a numerical method for optimally tailoring the CNT distribution pattern of FG-CNTRC beams. As a preliminary stage, the effective stress is defined as the objective function and the layer-wise CNT volume fractions are chosen as the design variables. The exterior penalty-function method and golden section method are adopted for the optimization formulation, together with finite difference scheme for the design sensitivity analysis. The proposed optimization method is illustrated and validated through the benchmark experiments, such that it successfully provides an optimum CNT distribution which can significantly minimize the effective stress, with a stable and rapid convergence in the iterative optimization process

Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)

Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate – a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle^(–1)). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies

Filler wire for aluminum alloys and method of welding

A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required

Silicon-compatible high-hole-mobility transistor with an undoped germanium channel for low-power application

In this work, Ge-based high-hole-mobility transistor with Si compatibility is designed, and its performance is evaluated. A 2-dimensional hole gas is effectively constructed by a AlGaAs/Ge/Si heterojunction with a sufficiently large valence band offset. Moreover, an intrinsic Ge channel is exploited so that high hole mobility is preserved without dopant scattering. Effects of design parameters such as gate length, Ge channel thickness, and aluminum fraction in the barrier material on device characteristics are thoroughly investigated through device simulations. A high on-current above 30 ??A/??m along with a low subthreshold swing was obtained from an optimized planar device for low-power applications.open0

Measuring Crime And Deviance: Law Enforcement Off The Pavement

This study operationalized quantitative measures of crime and deviance through the categorization of coding narrative violations as a specific section of the law. The aggregate number of violations in the game and fish, waters of the state, ports, and watercraft, and conservation and natural resources categories, which make up the majority of the total violations, suggests that these laws may be a priority for law enforcement or that there are many people violating these rules. However, without more information it is difficult to say what is significant about the data without more context. The difference in citations and warnings between the crimes and offenses category and the motor vehicles and traffic category may be due to various factors such as the complexity of offenses, enforcement priorities, and ease of enforcing specific rules. Moreover, the relatively low percentage of violations in the alcoholic beverages, criminal procedure, health, and insurance categories suggests that these codes are not as heavily enforced or may be less relevant to the studied population. Therefore, this study highlights the need for detailed incident-based data to measure the extent of game warden work overlap with routine law enforcement, and for a nuanced understanding of the factors that influence enforcement priorities and strategies

Interferon regulatory factor-1 (irf-1) shapes both innate and cd8 + t cell immune responses against west nile virus infection

Interferon regulatory factor (IRF)-1 is an immunomodulatory transcription factor that functions downstream of pathogen recognition receptor signaling and has been implicated as a regulator of type I interferon (IFN)-αβ expression and the immune response to virus infections. However, this role for IRF-1 remains controversial because altered type I IFN responses have not been systemically observed in IRF-1 -/- mice. To evaluate the relationship of IRF-1 and immune regulation, we assessed West Nile virus (WNV) infectivity and the host response in IRF-1 -/- cells and mice. IRF-1 -/- mice were highly vulnerable to WNV infection with enhanced viral replication in peripheral tissues and rapid dissemination into the central nervous system. Ex vivo analysis revealed a cell-type specific antiviral role as IRF-1 -/- macrophages supported enhanced WNV replication but infection was unaltered in IRF-1 -/- fibroblasts. IRF-1 also had an independent and paradoxical effect on CD8 + T cell expansion. Although markedly fewer CD8 + T cells were observed in naïve animals as described previously, remarkably, IRF-1 -/- mice rapidly expanded their pool of WNV-specific cytolytic CD8 + T cells. Adoptive transfer and in vitro proliferation experiments established both cell-intrinsic and cell-extrinsic effects of IRF-1 on the expansion of CD8 + T cells. Thus, IRF-1 restricts WNV infection by modulating the expression of innate antiviral effector molecules while shaping the antigen-specific CD8 + T cell response

One-Parameter Squeezed Gaussian States of Time-Dependent Harmonic Oscillator and Selection Rule for Vacuum States

By using the invariant method we find one-parameter squeezed Gaussian states for both time-independent and time-dependent oscillators. The squeezing parameter is expressed in terms of energy expectation value for time-independent case and represents the degree of mixing positive and negative frequency solutions for time-dependent case. A {\it minimum uncertainty proposal} is advanced to select uniquely vacuum states at each moment of time. We show that the Gaussian states with minimum uncertainty coincide with the true vacuum state for time-independent oscillator and the Bunch-Davies vacuum for a massive scalar field in a de Sitter spacetime.Comment: 13 Pages, ReVTeX, no figure

Maintenance of non-pharmacological strategies 6 months after patients with chronic obstructive pulmonary disease (COPD) attend a breathlessness service: a qualitative study

Objectives This study aimed to explore the degree to which non-pharmacological strategies for chronic breathlessness are sustained 6 months after completing a breathlessness service in patients with chronic obstructive pulmonary disease (COPD), and patient perceptions regarding the need for ongoing support. Design A qualitative approach was taken using semistructured telephone interviews. Thematic analysis used an integrative approach. Setting The Westmead Breathlessness Service (WBS) trains patients with COPD to self-manage chronic breathlessness over an 8-week programme with multidisciplinary input and home visits. Participants Patients with moderate to very severe COPD who had completed the WBS programme 6 months earlier. Results Thirty-two participants were interviewed. One or more breathlessness self-management strategies were sustained by most participants, including breathing techniques (n=22; 69%), the hand-held fan (n=17; 53%), planning/pacing and exercise (n=14 for each; 44%) and strategic use of a four-wheeled walker (n=8; 25%). However, almost a third of participants appeared to be struggling psychologically, including some who had refused psychological intervention. A ‘chaos narrative’ appeared to be prevalent, and many participants had poor recall of the programme. Conclusions Self-management strategies taught by breathlessness services to patients with moderate to very severe COPD have potential to be sustained 6 months later. However, psychological coping may be more challenging to maintain. Research is needed on ways to improve resilience to set-backs and uptake of psychological interventions, as well as to understand and address the implications of poor recall for self-management. Trial registration number ACTRN1261700049938

Improved methods for detection of β-galactosidase (lacZ) activity in hard tissue

The ß-galactosidase gene (lacZ) of Escherichia coli is widely used as a reporter gene. The expression of lacZ can be detected by enzyme-based histochemical staining using chromogenic substrates such as 5-bromo-4-chloro-3-indolyl-ß-D: -galactoside (X-gal). Because the enzymatic activity of lacZ is vulnerable to high temperatures and acid treatment for demineralization, detection of lacZ on paraffinized sections is difficult, especially for hard tissues, which require demineralization before sectioning in paraffin. To circumvent this problem, whole-mount X-gal staining before sectioning is performed. However, detection of lacZ activity in the center of larger portions of hard whole adult tissues is challenging. In this study, focusing on fixation procedures, we determined the conditions conducive to improved detection of lacZ activity in deeper areas of whole tissues. We used an annexin a5 (Anxa5)-lacZ reporter mouse model in which the Anxa5 expression in hard tissue is indicated by lacZ activity. We found that lacZ activity could be detected throughout the periodontal ligament of adult mice when fixed in 100% acetone, whereas it was not detected in the periodontal ligament around the root apex fixed in glutaraldehyde and paraformaldehyde. This staining could not be detected in wild-type mice. Acetone maintains the lacZ activity within 48 h of fixation at both 4°C and at room temperature. In conclusion, acetone is the optimal fixative to improve permeability for staining of lacZ activity in large volumes of adult hard tissues