Design and analysis of a compliant parallel pan-tilt platform

In combination of the advantages of both parallel mechanisms and compliant mechanisms, a compliant parallel mechanism with two rotational DOFs (degrees of freedom) is designed to meet the requirement of a lightweight and compact pan-tilt platform. Firstly, two commonly-used design methods i.e. direct substitution and FACT (Freedom and Constraint Topology) are applied to design the configuration of the pan-tilt system, and similarities and differences of the two design alternatives are compared. Then inverse kinematic analysis of the candidate mechanism is implemented by using the pseudo-rigid-body model (PRBM), and the Jacobian related to its differential kinematics is further derived to help designer realize dynamic analysis of the 8R compliant mechanism. In addition, the mechanism’s maximum stress existing within its workspace is tested by finite element analysis. Finally, a method to determine joint damping of the flexure hinge is presented, which aims at exploring the effect of joint damping on actuator selection and real-time control. To the authors’ knowledge, almost no existing literature concerns with this issue

Carrier Dynamics in Submonolayer InGaAs/GaAs Quantum Dots

Carrier dynamics of submonolayer (SML) InGaAs/GaAs quantum dots (QDs) were studied by micro-photoluminecence (MPL), selectively excited photoluminescence (SEPL), and time-resolved photoluminescence (TRPL). MPL and SEPL show the coexistence of localized and delocalized states, and different local phonon modes. TRPL reveal shorter recombination lifetimes and longer capture times for the QDs with higher emission energy. This suggests that the smallest SML QDs are formed by perfectly vertically correlated 2D InAs islands, having the highest In content and the lowest emission energy, while a slight deviation from the perfectly vertical correlation produces larger QDs with lower In content and higher emission energy.Comment: 12 pages, 5 figure

Identification of Virulence Factors in Edwardsiella Ictaluri

Edwardsiella ictaluri is the causative agent of enteric septicemia of catfish (ESC), which is one of the most important diseases impacting the US catfish industry. Though this disease has been very common, progress has been slow to find an economical and practical treatment method. Our long-term goal is to determine the mechanisms of E. ictaluri virulence in ESC. The overall objective of this study was to identify E. ictaluri genes required for host encounter and serum resistance and to determine their roles in pathogenesis. The central hypothesis is that E. ictaluri must differentially regulate its genes to invade fish and evade host defenses, thus, mutation of these differentially expressed genes (DEG) should cause attenuation of E. ictaluri virulence. To test this hypothesis, we first determined the global gene expression patterns of the wild type (wt) E. ictaluri 93-146 and EiAKMut02 mutant during catfish encounter and serum exposure using microarray analysis. Results indicated that in E. ictaluri wt, 377 and 16 DEGs were identified during host encounter and serum exposure, respectively. In EiAKMut02, 82 and 296 DEGs were identified during host encounter and serum experiment. Through functional analysis using Blast2GO, PSORTb, Host Pathogen Interaction Database (HPIDB), and Microbe Virulence Database (MVirDB), 38 DEGs in 9 KEGG pathways have been identified as potential virulence factors. The KEGG pathways represented were 1) bacterial secretion system including T3SS and T6SS, 2) ABC transporters including cystine transport system, iron complex transport system, d-methionine transport system, arginine transport system, thiamine transport system, and molybdate transport system, 3) protein export, 4) flagellar assembly, 5) two-component system, 6) bacterial chemotaxis, 7) ascorbate and aldarate metabolism, 8) phosphotransferase system, and 9) metabolic pathways. In order to understand their role in the E. ictaluri virulence, selected DEGs were inrame deleted by allelic exchange, and their virulence and efficacy were characterized in channel catfish fingerlings. Our results showed that the virulence of E. ictaluri ssaV and yscR mutants was completely attenuated while their efficacies were moderate in catfish fingerlings. These results support that the T3SS and T6SS, ABC transporters, protein export, and flagella seem to be important in E. ictaluri virulence

Beam shaping by nonlinear moir\'e metasurfaces

This paper explores the interplay of momentum transfer and nonlinear optical processes through moir\'e phenomena. Momentum transfer plays a crucial role in the interaction between photons and matter. Here, we study stacked metasurfaces with tailored dispersion and rotated against each other with varying twisted angles. The stacking introduces interlayer interactions, which can be controlled by the relative angle between metasurfaces, significantly enriching the resulting response compared to the single layer counterpart. By focusing on second-harmonic generation (SHG) from these twisted metasurfaces, we delve into the realm of nonlinear moir\'e photonics. Through experimental observations, we unveil the emergence of intricate far-field SHG radiation patterns, showing their effective tuning by varying the twisted angles. These findings offer a fresh perspective to explore nonlinear wavefront shaping through moir\'e phenomena, opening new avenues for nonlinear information processing, optical steering, and nonlinear optical switching.Comment: 10 pages, 5 figure

Thirty-six months recurrence after acute ischemic stroke among patients with comorbid type 2 diabetes: A nested case-control study

Background: Stroke patients have to face a high risk of recurrence, especially for those with comorbid T2DM, which usually lead to much more serious neurologic damage and an increased likelihood of death. This study aimed to explore determinants of stroke relapse among patients with comorbid T2DM. Materials and methods: We conducted this case-control study nested a prospective cohort of ischemic stroke (IS) with comorbid T2DM. During 36-month follow-up, the second stroke occurred in 84 diabetic IS patients who were allocated into the case group, while 613 patients without recurrence were the controls. We collected the demographic data, behaviors and habits, therapies, and family history at baseline, and measured the variables during follow-up. LASSO and Logistic regression analyses were carried out to develop a prediction model of stroke recurrence. The receiver operator characteristic (ROC) curve was employed to evaluate the performance of the prediction model. Results: Compared to participants without recurrence, the higher levels of pulse rate (78.29 ± 12.79 vs. 74.88 ± 10.93) and hypertension (72.6 vs. 61.2 %) were recorded at baseline. Moreover, a lower level of physical activity (77.4 vs. 90.4 %), as well as a higher proportion of hypoglycemic therapy (36.9 vs. 23.3 %) was also observed during 36-month follow-up. Multivariate logistic regression revealed that higher pulse rate at admission (OR = 1.027, 95 % CI = 1.005 – 1.049), lacking physical activity (OR = 2.838, 9 5 % CI = 1.418 – 5.620) and not receiving hypoglycemic therapy (OR = 1.697, 95 % CI = 1.013 – 2.843) during follow-up increased the risk of stroke recurrence. We developed a prediction model using baseline pulse rate, hypoglycemic therapy, and physical activity, which produced an area under ROC curve (AUC) of 0.689. Conclusion: Physical activity and hypoglycemic therapy play a protective role for IS patients with comorbid diabetes. In addition to targeted therapeutics, the improvement of daily-life habit contributes to slowing the progress of the IS

The efficacy of different types of cerebral embolic protection device during transcatheter aortic valve implantation: a meta-analysis

AimsPerioperative stroke remains a devastating complication after transcatheter aortic valve implantation (TAVI), and using a cerebral embolic protection device (CEPD) during TAVI may reduce the occurrence of stroke according to some studies. Therefore, we conducted this meta-analysis to determine whether CEPD should be routinely used during TAVI.Methods and resultsThe inclusion criteria for this study were randomized controlled trials (RCTs) that examined the outcome of stroke with or without CEPD during TAVI, with a minimum follow-up period of 30 days. The primary endpoint was the occurrence of stroke (including both cerebrovascular accidents and death due to cerebrovascular accidents). The risk of stroke was lower in the CEPD group: RR 0.68, 95% CI 0.49–0.96, p = 0.03, I2 = 0%. A subgroup analysis was conducted according to the type of CEPD. The risk of stroke was lower in the I&LCCA (filter cover the innominate and the left common carotid arteries) type CEPD group: RR 0.66, 95% CI 0.49–0.96, p = 0.03, I2 = 36%. However, there was no statistically significant difference in the risk of stroke in the TMCA [filter cover the three major cerebral arteries (innominate, left common carotid, and subclavian arteries)] type CEPD group: RR 0.81, 95% CI 0.36–1.80, p = 0.60, I2 = 0%.ConclusionsIn this meta-analysis, the I&LCCA-type CEPD can reduce the risk of stroke within 30 days following TAVI, but the TMCA type cannot

Design and evaluation of a rodent-specific focal transcranial magnetic stimulation coil with the custom shielding application in rats

Repetitive TMS has been used as an alternative treatment for various neurological disorders. However, most TMS mechanism studies in rodents have been based on the whole brain stimulation, the lack of rodent-specific focal TMS coils restricts the proper translation of human TMS protocols to animal models. In this study, we designed a new shielding device, which was made of high magnetic permeability material, to enhance the spatial focus of animal-use TMS coils. With the finite element method, we analyzed the electromagnetic field of the coil with and without the shielding device. Furthermore, to assess the shielding effect in rodents, we compared the c-fos expression, the ALFF and ReHo values in different groups following a 15 min 5 Hz rTMS paradigm. We found that a smaller focality with an identical core stimulation intensity was achieved in the shielding device. The 1 T magnetic field was reduced from 19.1 mm to 13 mm in diameter, and 7.5 to 5.6 mm in depth. However, the core magnetic field over 1.5 T was almost the same. Meanwhile, the area of electric field was reduced from 4.68 cm2 to 4.19 cm2, and 3.8 mm to 2.6 mm in depth. Similar to this biomimetic data, the c-fos expression, the ALFF and ReHo values showed more limited cortex activation with the use of the shielding device. However, compared to the rTMS group without the shielding application, more subcortical regions, like the striatum (CPu), the hippocampus, the thalamus, and the hypothalamus were also activated in the shielding group. This indicated that more deep stimulation may be achieved by the shielding device. Generally, compared with the commercial rodents’ TMS coil (15 mm in diameter), TMS coils with the shielding device achieved a better focality (~6 mm in diameter) by reducing at least 30% of the magnetic and electric field. This shielding device may provide a useful tool for further TMS studies in rodents, especially for more specific brain area stimulation