130 research outputs found
A CMOS relative ultrasound energy measurement circuit with temperature compensation
No full textCMOS temperature compensated circuit used in measuring relative ultrasound energy is presented in this paper. The core of the circuit is a temperature compensated voltage to current squarer (VCSQ) and a current integrator. The VCSQ consists of a Linear-Transconductor(LTC) and a current-mode squarer. A current source (dependent on MOS transconductance which is in turn dependent on absolute temperature) is used to bias the current-mode squarer; this provides temperature compensation of the circuit. The circuit is simulated for AMI05 (0.5um) technology using Eldo in Mentor Graphics environment. With the compensation, the VCSQ output drift with temperature is achieved better than 1.98% in the 10~90°C range for ±1.2V input range. The integrator output drift is achieved for full scale error better than 2.5% in the 10-90°C range, 1.6% in the 30~90°C range. © Copyright 2011 IEEE – All Rights Reserve
Pediatr Infect Dis J
No full textBackgroundIn China, varicella vaccine has been available in the private sector to children 6512 months of age since 1998 with a single-dose indication. In December 2006, varicella became a notifiable disease in Beijing. We used surveillance data to describe varicella vaccine uptake from 2005 to 2010 and varicella epidemiology in Beijing from 2007 to 2010.MethodsLimited sociodemographic and clinical information was available from the passive surveillance system. Varicella vaccine coverage was estimated for each year for children born between 2004 and 2008 using the number of children in the immunization registry of each birth year as the denominator without adjustment for history of varicella.ResultsVaccine coverage increased within each birth cohort between 2005 and 2010. The coverage at 2 years of age increased from 62.4% in 2005 to 74.1% in 2010 and was 80.4% in children 3\u20136 years of age in 2010. Between 2007 and 2010, 15,544 to 18,256 varicella cases were reported annually with stable overall incidence (range: 1.0\u20131.1/1000 persons), but the incidence in children 1\u20134 years of age decreased significantly from 6.2 per 1000 children in 2007 to 4.4 per 1000 children in 2010 (P < 0.001). Among adults ( 6520 years of age), there were significant increases in the number and proportion of cases from 2557 (16.5%) in 2007 to 4277 (23.4%) in 2010 (P < 0.001).ConclusionsModerately high 1-dose vaccine coverage in young children has been achieved with declining disease incidence, but varicella remains a common, seasonal disease in the population. Current epidemiology suggests that a government-funded varicella vaccine program that includes catch-up vaccination for older children, adolescents and adults needs consideration.CC999999/Intramural CDC HHSUnited States
Vaccine
No full textBackgroundTwo-dose varicella vaccination has been available in Beijing since 2012 in the private sector. We investigated a varicella outbreak in a highly vaccinated elementary school population.MethodsA cohort study was carried out and a varicella case was defined as an acute onset of generalized maculopapulovesicular rash without other apparent cause in a student attending the school from March 29 through May 17, 2015. Breakthrough varicella was defined as varicella >42 days after the last vaccine dose among both 1- or 2-dose varicella vaccine recipients. Vaccination information was collected from immunization records; information on prior varicella and clinical presentations was collected by surveying students\u2019 parents.ResultsOf the 1056 students in the school, 1027 (97.3%) reported no history of varicella. Prior to the outbreak, 98.6% of students had received 651 dose of varicella vaccine, and most (63.2%) students received two doses. Twenty varicella cases were identified for an overall attack rate of 2.0%. Half of the cases occurred in the classroom of the index case-patient, a two-dose recipient who was not isolated after symptom onset. Breakthrough varicella accounted for 95% of cases (19/20) with attack rates of 14.3% (1/7), 1.6% (6/362) and 2.0% (13/649) among unvaccinated, one-dose, and two-dose students, respectively. Most case-patients (18/20, 90%) had <50 lesions. No difference in clinical presentations was found between one-dose and two-dose recipients with breakthrough varicella.ConclusionModerate two-dose varicella vaccine coverage was insufficient to prevent a varicella outbreak. Two-dose recipients with breakthrough varicella are contagious. High two-dose varicella vaccine coverage and timely isolation of cases may be needed for varicella outbreak prevention in the two-dose era.CC999999/Intramural CDC HHSUnited States
Vaccine
No full textBackgroundVaricella vaccine is available in the private sector in China, with a single dose currently recommended for children aged 6512 months. We investigated a varicella outbreak in a school in Beijing with high varicella vaccination coverage to describe the outbreak, examine risk factors for vaccine failure, and calculate vaccine effectiveness.MethodsA varicella case was defined as an acute generalized maculopapular rash without other apparent cause in a student without prior varicella attending the elementary school during August 30\u2013December 28, 2010. Varicella among vaccinated students (breakthrough varicella) was defined as varicella occurring >42 days after vaccination. Students\u2019 vaccination status was verified with immunization records and clinical presentations were collected from health care practitioners.ResultsOf the 951 students, 934 (98%) had no prior varicella history. Among these students, 916 had received 1 dose of varicella vaccine and 2 had received 2 doses (98% vaccination coverage) before the outbreak. A total of 87 cases occurred during the outbreak; most had breakthrough varicella (86/87, 99%) and mild disease (83/87, 95%). Age at vaccination (<15 months vs. 6515 months) and time since vaccination before outbreak (<5 years vs. 655 years) were not associated with development of breakthrough varicella. Single-dose varicella vaccination was 89% effective in preventing any varicella and 99% in preventing moderate/severe varicella.ConclusionSingle-dose varicella vaccination is highly effective in reducing varicella incidence and mitigating disease severity, but not high enough to prevent outbreak. A two-dose program might help to prevent varicella outbreaks in Beijing.CC999999/ImCDC/Intramural CDC HHSUnited States
Electroosmotic Flow in a Rough Nanochannel with Surface Roughness Characterized by Fractal Cantor
No full textMolecular dynamics simulation is applied to study the electroosmotic flow in rough nanochannels, with particular attention given to the fluid–solid interactions. In the simulation, the surface roughness is characterized by a fractal Cantor. The roles of roughness height and fractal dimension on nanoscale electroosmotic flow are examined and analyzed. The concentration distributions, zeta potential and electroosmotic velocity are presented and investigated. The results indicate that surface roughness plays a significant role in the fluid–solid interaction and nanoscale electroosmotic flow. The distribution of dipole angle for water molecules in both the near-wall region and middle region is almost unaffected by surface roughness; however, a significant difference of dipole angle distribution is observed in the fluid region away from the wall. Interestingly, the concentration distributions, electroosmotic velocity and zeta potential are highly affected by the surface fractal dimension, even with the same roughness height
An Adaptive Control Based on Improved Gray Wolf Algorithm for Mobile Robots
No full textIn this paper, a novel intelligent controller for the trajectory tracking control of a nonholonomic mobile robot with time-varying parameter uncertainty and external disturbances in the case of tire hysteresis loss is proposed. Based on tire dynamics principles, a dynamic and kinematic model of a nonholonomic mobile robot is established, and the neural network approximation model of the system’s nonlinear term caused by many coupling factors when the robot enters a roll is given. Then, in order to adaptively estimate the unknown upper bounds on the uncertainties and perturbations for each subsystem in real time, a novel adaptive law employed online as a gain parameter is designed to solve the problem of inter-system coupling and reduce the transient response time of the system with lower uncertainties. Additionally, based on improved gray wolf optimizer and fuzzy system techniques, an adaptive algorithm using the gray wolf optimizer study space as the output variable of the fuzzy system to expand the search area of the gray wolves is developed to optimize the controller parameters online. Finally, the efficacy of the proposed intelligent control scheme and the feasibility of the proposed algorithm are verified by the 2023a version of MATLAB/Simulink platform
Non-Negative Matrix Factorization with Averaged Kurtosis and Manifold Constraints for Blind Hyperspectral Unmixing
No full textThe Nonnegative Matrix Factorization (NMF) algorithm and its variants have gained widespread popularity across various domains, including neural networks, text clustering, image processing, and signal analysis. In the context of hyperspectral unmixing (HU), an important task involving the accurate extraction of endmembers from mixed spectra, researchers have been actively exploring different regularization techniques within the traditional NMF framework. These techniques aim to improve the precision and reliability of the endmember extraction process in HU. In this study, we propose a novel HU algorithm called KMBNMF, which introduces an average kurtosis regularization term based on endmember spectra to enhance endmember extraction, additionally, it integrates a manifold regularization term into the average kurtosis-constrained NMF by constructing a symmetric weight matrix. This combination of these two regularization techniques not only optimizes the extraction process of independent endmembers but also improves the part-based representation capability of hyperspectral data. Experimental results obtained from simulated and real-world hyperspectral datasets demonstrate the competitive performance of the proposed KMBNMF algorithm when compared to state-of-the-art algorithms
Distribution-Free Model for Ambulance Location Problem with Ambiguous Demand
No full textAmbulance location problem is a key issue in Emergency Medical Service (EMS) system, which is to determine where to locate ambulances such that the emergency calls can be responded efficiently. Most related researches focus on deterministic problems or assume that the probability distribution of demand can be estimated. In practice, however, it is difficult to obtain perfect information on probability distribution. This paper investigates the ambulance location problem with partial demand information; i.e., only the mean and covariance matrix of the demands are known. The problem consists of determining base locations and the employment of ambulances, to minimize the total cost. A new distribution-free chance constrained model is proposed. Then two approximated mixed integer programming (MIP) formulations are developed to solve it. Finally, numerical experiments on benchmarks (Nickel et al., 2016) and 120 randomly generated instances are conducted, and computational results show that our proposed two formulations can ensure a high service level in a short time. Specifically, the second formulation takes less cost while guaranteeing an appropriate service level
UV photochemical vapor generation sample introduction for determination of Ni, Fe, and Se in biological tissue by isotope dilution ICPMS
No full textA novel, sensitive method is described for the accurate determination of Ni, Se, and Fe in biological tissues by isotope dilution inductively coupled plasma mass spectrometry (ID ICPMS) based on sample introduction arising from online UV photochemical vapor generation (UV-PVG). Volatile species of Ni, Se, and Fe were liberated from a formic acid medium following exposure to a UV source. Sensitivities were enhanced 27- to 355-fold compared to those obtained using pneumatic nebulization sample introduction. Although precision was slightly degraded (a factor of 2) with ultraviolet photochemical mediated vapor generation (UV-PVG), limits of detection (LODs) of 0.18, 1.7, and 1.0 pg g 121 for Ni, Se, and Fe, respectively, based on an external calibration, provided 28-, 150-, and 29-fold improvements over that realized with conventional pneumatic solution nebulization. Method validation was demonstrated by determination of Ni, Se, and Fe in biological tissue certified reference materials (CRMs) TORT-2 and DORM-3. Concentrations of 2.33 \ub1 0.03, 5.80 \ub1 0.28, and 109 \ub1 2 \u3bcg g 121 (1SD, n = 4) and 1.31 \ub1 0.04, 3.35 \ub1 0.18, and 353 \ub1 5 \u3bcg g 121 (1SD, n = 4) for Ni, Se, and Fe, respectively were obtained in TORT-2 and DORM-3, in good agreement with certified values.Cet article d\ue9crit une nouvelle m\ue9thode dont la sensibilit\ue9 permet de doser avec pr\ue9cision le nickel (Ni), le s\ue9l\ue9nium (Se) et le fer (Fe) contenus dans les tissus biologiques en combinant dilution isotopique et spectrom\ue9trie de masse par plasma \ue0 couplage inductif (ICP-MS ID). Cette m\ue9thode repose sur l'introduction de l\u2019\ue9chantillon par g\ue9n\ue9ration photochimique de vapeur \ue0 l\u2019aide d\u2019une source UV en ligne (UV-PVG). Les esp\ue8ces volatiles de Ni, de Se et de Fe ont \ue9t\ue9 extraites d\u2019une solution d\u2019acide formique par exposition \ue0 une source d\u2019UV. Cette m\ue9thode d\u2019introduction des \ue9chantillons s\u2019est av\ue9r\ue9e de 27 \ue0 355 fois plus sensible que la m\ue9thode de n\ue9bulisation pneumatique. Bien que le degr\ue9 de pr\ue9cision diminue l\ue9g\ue8rement (facteur 2) en raison de l\u2019UV-PVG, les limites de d\ue9tection (LD) \ue9tablies \ue0 partir d\u2019une courbe d\u2019\ue9talonnage externe sont de 0,18, 1,7 et 1,0 pg/g pour le Ni, le Se, et le Fe respectivement, ce qui repr\ue9sente une am\ue9lioration de 28, 150, et 29 fois par rapport aux valeurs obtenues avec un n\ue9bulisateur pneumatique conventionnel. Nous avons valid\ue9 cette m\ue9thode en effectuant des dosages de Ni, de Se et de Fe dans des tissus biologiques correspondant aux mat\ue9riaux de r\ue9f\ue9rence certifi\ue9s (MRC), TORT-2 et DORM-3. Les concentrations respectives de Ni, de Se et de Fe sont de 2,33 \ub1 0,03, 5,80 \ub1 0,28, et 109 \ub1 2 (1SD, n = 4) \u3bcg/g dans le cas de TORT-2 et de 1,31 \ub1 0,04, 3,35 \ub1 0,18, et 353 \ub1 5 \u3bcg/g (1SD, n = 4) dans le cas de DORM-3, et sont conformes aux valeurs certifi\ue9es.Peer reviewed: YesNRC publication: Ye
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