2,232 research outputs found
Recommended from our members
The Perceived Value Among Employers of College Study Abroad for Engineers
Engineering graduates of the twenty-first century must be worldly and understand how to work with professionals from many cultures on projects that cross international boundaries. Increasingly, employers are finding that prospective employees who have studied abroad make better, more rounded candidates than those who have no life experience outside of their home region. The objective of this study was to determine whether engineering students who participate in a major-specific, study abroad experience are more desirable as candidates for employment than those who only study at their home institution. This descriptive study surveyed the membership of the combined Industrial Advisory Boards of the University of North Texas College of Engineering (n=90) which is a focused group of skilled managers and directors that represent various businesses, industries and organizations. The survey yielded a 58% response rate. The evaluation was validated by a survey that searched for a perceptual trend among representatives from business and industry who are in a hiring capacity for engineering graduates, evaluating a major-specific study abroad experience as part of a graduate’s employability and career growth. Statistical Analysis was made on Companies whose scope of business is domestic and international comparing the perceived value of study abroad as a characteristic for hiring new engineers, as well as comparing the perceived value of foreign study or work experience on the career development of engineers. These tests indicated that at the 0.05 level there was no statistical significance in the findings. Additional analysis was made on groups of employees that either had foreign experience (work or study) and those that did not. These tests indicated that there was no statistical significance in the findings. Analysis of the data indicates that although having a major specific study abroad experience may not be important at the entry level, it becomes more important as an engineer progresses into mid-career. It could also indicate change in the business climate and a growing need for global awareness. Additional observations show that other co-curricular activities, such as internships and grades weigh more in the hiring of a new engineering graduate
Synchronization in a neuronal feedback loop through asymmetric temporal delays
We consider the effect of asymmetric temporal delays in a system of two
coupled Hopfield neurons. For couplings of opposite signs, a limit cycle
emerges via a supercritical Hopf bifurcation when the sum of the delays reaches
a critical value. We show that the angular frequency of the limit cycle is
independent of an asymmetry in the delays. However, the delay asymmetry
determines the phase difference between the periodic activities of the two
components. Specifically, when the connection with negative coupling has a
delay much larger than the delay for the positive coupling, the system
approaches in-phase synchrony between the two components. Employing variational
perturbation theory (VPT), we achieve an approximate analytical evaluation of
the phase shift, in good agreement with numerical results.Comment: 5 pages, 4 figure
Contrast-enhanced micro-CT imaging in murine carotid arteries : a new protocol for computing wall shear stress
Background: Wall shear stress (WSS) is involved in the pathophysiology of atherosclerosis. The correlation between WSS and atherosclerosis can be investigated over time using a WSS-manipulated atherosclerotic mouse model. To determine WSS in vivo, detailed 3D geometry of the vessel network is required. However, a protocol to reconstruct 3D murine vasculature using this animal model is lacking. In this project, we evaluated the adequacy of eXIA 160, a small animal contrast agent, for assessing murine vascular network on micro-CT. Also, a protocol was established for vessel geometry segmentation and WSS analysis. Methods: A tapering cast was placed around the right common carotid artery (RCCA) of ApoE(-/-) mice (n = 8). Contrast-enhanced micro-CT was performed using eXIA 160. An innovative local threshold-based segmentation procedure was implemented to reconstruct 3D geometry of the RCCA. The reconstructed RCCA was compared to the vessel geometry using a global threshold-based segmentation method. Computational fluid dynamics was applied to compute the velocity field and WSS distribution along the RCCA. Results: eXIA 160-enhanced micro-CT allowed clear visualization and assessment of the RCCA in all eight animals. No adverse biological effects were observed from the use of eXIA 160. Segmentation using local threshold values generated more accurate RCCA geometry than the global threshold-based approach. Mouse-specific velocity data and the RCCA geometry generated 3D WSS maps with high resolution, enabling quantitative analysis of WSS. In all animals, we observed low WSS upstream of the cast. Downstream of the cast, asymmetric WSS patterns were revealed with variation in size and location between animals. Conclusions: eXIA 160 provided good contrast to reconstruct 3D vessel geometry and determine WSS patterns in the RCCA of the atherosclerotic mouse model. We established a novel local threshold-based segmentation protocol for RCCA reconstruction and WSS computation. The observed differences between animals indicate the necessity to use mouse-specific data for WSS analysis. For our future work, our protocol makes it possible to study in vivo WSS longitudinally over a growing plaque
Typifications of five names in Agarista (Ericaceae, Vaccinioideae, Lyonieae).
Five names are typified here as a first step towards the floristic and taxonomic study of Ericaceae in Rio Grande do Sul state, Brazil, and the taxonomic revision of Agarista. We reviewed protologues, type specimens (including digital images), and negative photos at F from lost specimens originally deposited at B. Lectotypes are designated for the names Andromeda chlorantha, A. serrulata, A. eucalyptoides, A. multiflora, and A. nummularia. These lectotypes are designated from duplicates conserved in the herbaria E, F, HAL, G, GH, L, M, NY, S, and W. Additionally, epitypes are also designated for Agarista chlorantha and Agarista nummularia at ESA and US, respectively
Vortex microavalanches in superconducting Pb thin films
Local magnetization measurements on 100 nm type-II superconducting Pb thin
films show that flux penetration changes qualitatively with temperature. Small
flux jumps at the lowest temperatures gradually increase in size, then
disappear near T = 0.7Tc. Comparison with other experiments suggests that the
avalanches correspond to dendritic flux protrusions. Reproducibility of the
first flux jumps in a decreasing magnetic field indicates a role for defect
structure in determining avalanches. We also find a temperature-independent
final magnetization after flux jumps, analogous to the angle of repose of a
sandpile.Comment: 6 pages, 5 figure
FINITE ELEMENT MODELING OF A TRANSFORMER FEEDING A RECTIFIED LOAD: THE COUPLED POWER ELECTRONICS AND NONLINEAR MAGNETIC FIELD PROBLEM
Abstract-Zedimensional finite elements are used to help directly incorporate models of nonlinear power electronic switching devices into nonlinear transient magnetic finite element analysis. Iko applications are considered: a buck regulator circuit and a transformer feeding a rectified load
Breaking the Waves: Modelling the Potential Impact of Public Health Measures to Defer the Epidemic Peak of Novel Influenza A/H1N1
BACKGROUND: On June 11, 2009, the World Health Organization declared phase 6 of the novel influenza A/H1N1 pandemic. Although by the end of September 2009, the novel virus had been reported from all continents, the impact in most countries of the northern hemisphere has been limited. The return of the virus in a second wave would encounter populations that are still nonimmune and not vaccinated yet. We modelled the effect of control strategies to reduce the spread with the goal to defer the epidemic wave in a country where it is detected in a very early stage. METHODOLOGY/PRINCIPAL FINDINGS: We constructed a deterministic SEIR model using the age distribution and size of the population of Germany based on the observed number of imported cases and the early findings for the epidemiologic characteristics described by Fraser (Science, 2009). We propose a two-step control strategy with an initial effort to trace, quarantine, and selectively give prophylactic treatment to contacts of the first 100 to 500 cases. In the second step, the same measures are focused on the households of the next 5,000 to 10,000 cases. As a result, the peak of the epidemic could be delayed up to 7.6 weeks if up to 30% of cases are detected. However, the cumulative attack rates would not change. Necessary doses of antivirals would be less than the number of treatment courses for 0.1% of the population. In a sensitivity analysis, both case detection rate and the variation of R0 have major effects on the resulting delay. CONCLUSIONS/SIGNIFICANCE: Control strategies that reduce the spread of the disease during the early phase of a pandemic wave may lead to a substantial delay of the epidemic. Since prophylactic treatment is only offered to the contacts of the first 10,000 cases, the amount of antivirals needed is still very limited
Hormone replacement therapy, mammography screening and changing age-specific incidence rates of breast cancer: an ecological study comparing two European populations
Background: In 2003, for the first time, US breast cancer incidence rates have fallen. Experts argue whether this is due to the reduced uptake of screening mammography or to lower use of Hormone Replacement Therapy (HRT). This study aims to disentangle the respective impact of screening and HRT on age-incidence rates and histology of breast cancer, by comparing two populations with comparably high levels of screening mammography, but with different prevalence of HRT. Methods: We included all invasive breast cancers recorded at the Geneva cancer registry (n=4,909) and the Netherlands Cancer Registry (n=152,428) between 1989-2003. We compared age-specific incidence rates and trends in histological subtyping between the two populations. Results: Between 1989-1991, incidence rates increased with age in both populations. In 2001-2003, women aged 60-64years showed highest incidence rates in Geneva, while in the Netherlands incidence rates continued to increase with age. The annual increase in ductal cancer incidence was similar in the Netherlands (2.3%) and Geneva (2.5%), but the annual increase in lobular cancer was sharper in Geneva (10%) than in the Netherlands (5%). Conclusion: The sharp differences in age distribution and histological subtyping of breast cancer between two European populations are not attributable to screening, since both populations have a high uptake of mammography screening. Since the prevalence of HRT use is very high in Geneva and rather low in the Netherlands, HRT may explain these discrepancies. However, other etiological factors and differences in histological assessment may also have played a rol
- …