The static and dynamic structural bulk properties of fibrous media

The structural bulk properties of fibrous materials are investigated. Theoretical models are developed and their predictions are compared to measured data. The properties under both static loading and dynamic excitation are studied.Macro-scale experimental models are constructed to represent the idealised microscopic structure and to investigate its static behaviour under compression. As a result, the dominant mechanisms of deflection and nonlinearity are respectively identified as bending and the increase in the number of inter-fibre contacts under compression. Exploratory investigations concerning friction and electric contact resistance are conducted on macro-scale models. As an effective means of representing its structural characteristic, a transversely isotropic structure of stacked cylinders is employed to model a bulk fibrous material. Based on this, static bending models are formulated to describe the structural nonlinear stress-strain behaviour of bulk fibrous media under static compression. In these models, the increase in the number of inter-fibre contacts is related to the shortening of fibre links, and is also further examined in terms of "connectivity'' inside a medium. Similarities to, and differences from, percolation theory are noted.The dynamic structural bulk properties of fibrous materials are also investigated. Their nonlinear behaviour is dealt with mainly in terms of dependence on the amplitude of excitation, and is characterised by shifts in the measured transmissibility and the corresponding complex Young's modulus.As in the case of the static properties, the dynamic behaviour of a fibrous material is also investigated by means of idealised models, which show that the nonlinear mechanism is similar to that in the static case.A novel method is proposed to improve the efficacy in measuring the dynamic properties of a bulk fibrous material. The new method combines the advantages of two conventional techniques, the transfer function method and the mechanical impedance method. Finally, a nonlinear governing partial differential equation is derived for the dynamic behaviour of a bulk fibrous material. Its analogy to nonlinear equations in other types of media is observed. And the nonlinear behaviour, especially regarding the occurrence of harmonic components, is predicted in the theory as well as being confirmed by experiment

Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts

We have investigated the electrical Hanle effect with magnetic fields applied at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect, OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal measurement scheme. The electrical oblique Hanle signals obtained in CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes depending on the spin lifetime of the host SC. Notably, at moderate magnetic fields, the asymptotic values of the oblique Hanle signals (in both contacts) are consistently reduced by a factor of cos^2({\theta}) irrespective of the bias current and temperature. These results are in good agreement with predictions of the spin precession and relaxation model for the electrical oblique Hanle effect. At high magnetic fields where the magnetization of CoFe is significantly tilted from the film plane to the magnetic field direction, we find that the observed angular dependence of voltage signals in the CoFe/MgO/Si and CoFe/MgO/Ge contacts are well explained by the OHE, considering the misalignment angle between the external magnetic field and the magnetization of CoFe.Comment: 19 pages, 8 figure

Monte Carlo Analysis of the Accelerator-Driven System at Kyoto University Research Reactor Institute

An accelerator-driven system consists of a subcritical reactor and a controllable external neutron source. The reactor in an accelerator-driven system can sustain fission reactions in a subcritical state using an external neutron source, which is an intrinsic safety feature of the system. The system can provide efficient transmutations of nuclear wastes such as minor actinides and long-lived fission products and generate electricity. Recently at Kyoto University Research Reactor Institute (KURRI; Kyoto, Japan), a series of reactor physics experiments was conducted with the Kyoto University Critical Assembly and a Cockcroft-Walton type accelerator, which generates the external neutron source by deuterium-tritium reactions. In this paper, neutronic analyses of a series of experiments have been re-estimated by using the latest Monte Carlo code and nuclear data libraries. This feasibility study is presented through the comparison of Monte Carlo simulation results with measurements.clos

The orphan nuclear receptor SHP is a positive regulator of osteoblastic bone formation

The orphan nuclear receptor small heterodimer partner (SHP; NR0B2) interacts with a diverse array of transcription factors and regulates a variety of cellular events such as cell proliferation, differentiation, and metabolism. However, the role of SHP in bone formation has not yet been elucidated. SHP expression is significantly increased during osteoblast differentiation, and its expression is partially regulated by bone morphogenetic protein 2 (BMP-2), which plays an important role in bone formation. In our study, inhibition of SHP expression significantly repressed BMP-2-induced osteoblast differentiation and ectopic bone formation. In accordance with these in vitro and in vivo results, osteoblast differentiation in SHP −/− mice primary osteoblasts was significantly repressed, and the mice showed decreased bone mass resulting from decreased numbers of osteoblasts. Finally, SHP physically interacts and forms a complex with runt-related transcription factor 2 (Runx2) on the osteocalcin gene promoter, and overexpression of SHP increased Runx2 transactivity via competition with histone deacetylase 4 (HDAC4), an enzyme that inhibits DNA binding of Runx2 to its target genes. Taken together, these results indicate that SHP acts as a novel positive regulator of bone formation by augmenting osteoblast differentiation through regulation of the transcriptional activity of Runx2. © 2010 American Society for Bone and Mineral ResearchPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65055/1/90718_ftp.pd

A HISTORICAL APPROACH TO SYPHILIS INFECTION IN KOREA

From the end of the 15th century, syphilis spread worldwide, posing a serious threat to public health. Venereal syphilis has been a major research topic, not only in clinical medicine but also in paleopathology, especially because it is a disease of questionable origin and of high prevalence until the discovery of antibiotics. Syphilis in history has been studied extensively in Europe and the Americas, though less so in Asia. In this review, based on extant historical documents and available paleopathological data, we pinpoint the introduction and trace the spread of venereal syphilis in Korea to the end of the 19th century. This review provides fundamental information that will be of great help to future research on pre-20th century syphilis in Korea

Age-related changes of ocular parameters in Korean subjects

Aims: To evaluate the age-related variations of ocular parameters in Korean subjects. Methods: We recruited 314 normal subjects who visited the department of Ophthalmology between January 2007 and October 2007. Refraction, axial length, corneal curvature, white-to-white distance, anterior chamber depth, corneal endothelial cell density, and retinal nerve fiber layer (RNFL) thickness were measured using auto-refractive keratometer, intraocular lens master, noncontact specular microscope, and optical coherence tomography. Result: In correlation analysis, from 19 to 82 years, hyperopic shift showed a strong positive statistical correlation with age (r = 0.553, P < 0.001). Corneal curvatures increased (r = 0.221, P < 0.001), while axial length (r = -0.506, P < 0.001), anterior chamber depth (r = -0.491, P < 0.001) and white-to-white distance (r = -0.205, P < 0.001) decreased with age. Also, corneal endothelial cell density was lower in older patients than in younger patients (r = -0.409, P < 0.001). Compared to younger patients, RNFL thickness was lower in the older patients as well, in all quadrants (superior, r = -0.283, P < 0.001; inferior, r = -0.230, P < 0.001; nasal, r = 0.025, P = 0.676; and temporal, r = -0.393, P < 0.001). According to multiple regression analysis, out of the six parameters measured, only hyperopic shift, anterior chamber depth and corneal endothelial cell density (P, 0.05) had statistically significant correlation with age. Conclusion: Some of the ocular parameters changed with aging. Hyperopic shift, shallowing anterior chamber depth, and reduction of corneal endothelial cell density were only definitely related to age

Tiresias: Predicting Security Events Through Deep Learning

With the increased complexity of modern computer attacks, there is a need for defenders not only to detect malicious activity as it happens, but also to predict the specific steps that will be taken by an adversary when performing an attack. However this is still an open research problem, and previous research in predicting malicious events only looked at binary outcomes (e.g., whether an attack would happen or not), but not at the specific steps that an attacker would undertake. To fill this gap we present Tiresias, a system that leverages Recurrent Neural Networks (RNNs) to predict future events on a machine, based on previous observations. We test Tiresias on a dataset of 3.4 billion security events collected from a commercial intrusion prevention system, and show that our approach is effective in predicting the next event that will occur on a machine with a precision of up to 0.93. We also show that the models learned by Tiresias are reasonably stable over time, and provide a mechanism that can identify sudden drops in precision and trigger a retraining of the system. Finally, we show that the long-term memory typical of RNNs is key in performing event prediction, rendering simpler methods not up to the task