22,242 research outputs found

    Early life growth patterns persist for 12 years and impact pulmonary outcomes in cystic fibrosis

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    BACKGROUND: In children with cystic fibrosis (CF), recovery from growth faltering within 2 years of diagnosis (Responders) is associated with better growth and less lung disease at age 6 years. This study examined whether these benefits are sustained through 12 years of age. METHODS: Longitudinal growth from 76 children with CF enrolled in the Wisconsin CF Neonatal Screening Project was examined and categorized into 5 groups: R12, R6, and R2, representing Responders who maintained growth improvement to age 12, 6, and 2 years, respectively, and I6 and N6, representing Non-responders whose growth did and did not improve during ages 2-6 years, respectively. Lung disease was evaluated by % predicted forced expiratory volume in one second (FEV1) and chest radiograph (CXR) scores. RESULTS: Sixty-two percent were Responders. Within this group, 47% were R12, 28% were R6, and 25% were R2. Among Non-responders, 76% were N6. CF children with meconium ileus (MI) had worse lung function and CXR scores compared to other CF children. Among 53 children with pancreatic insufficiency without MI, R12 had significantly better FEV1 (97-99% predicted) and CXR scores during ages 6-12 years than N6 (89-93% predicted). Both R6 and R2 experienced a decline in FEV1 by ages 10-12 years. CONCLUSIONS: Early growth recovery in CF is critical, as malnutrition during infancy tends to persist and catch-up growth after age 2 years is difficult. The longer adequate growth was maintained after early growth recovery, the better the pulmonary outcomes at age 12 years

    Elastic metamaterials with simultaneously negative effective shear modulus and mass density

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    We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess negative shear modulus and negative mass density over a large frequency region. Such a solid metamaterial has a unique elastic property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample, and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids

    Effects of spatial elements and sound sources on sound field in Main Hall of Chinese Buddhist temple

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    In Chinese Han Buddhist temples, the Main Hall is the paramount indoor religious location, for which acoustic quality is very important for several Buddhist rites held within; however, the sound field in the Main Hall has not yet been analyzed scientifically. By combining sound field measurement with acoustic simulation, this study investigated the effects of spatial elements and sound source characteristics in a Main Hall, revealing that both fabric sound absorbers and Buddha statues mounted within had a pronounced effect on the sound field. Using an acoustic model of the Main Hall of the Xiantong Temple as an example, when various fabric sound absorbers were removed, the mid-frequency reverberation time (T30m) and mid-frequency early decay time (EDTm) increased by 32.3% and 46.8%, respectively. When fabric sound absorbers and Buddha statues were removed, the sound pressure level was not significantly affected. The form of the roof did not significantly impact the indoor sound field. The directivity of the sound sources did not significantly affect the T30m but did affect the EDTm and the speech transmission index (STI). When monks chanted sutras face-to-face, the STI was maximized. Additionally, changing the positions of sound sources moderately affected the EDT and STI

    Interrelation between radio and X-ray signatures of drifting subpulses in pulsars

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    We examined a model of partially screened gap region above the polar cap, in which the electron-positron plasma generated by sparking discharges coexists with thermionic flow ejected by the bombardment of the surface beneath these sparks. Our special interest was the polar cap heating rate and the subpulse drifting rate, both phenomena presumably associated with sparks operating at the polar cap. We investigated correlation between the intrinsic drift rate and polar cap heating rate and found that they are coupled to each other in such a way that the thermal X-ray luminosity LxL_x from heated polar cap depends only on the observational tertiary subpulse drift periodicity P^3\hat{P}_3 (polar cap carousel time). Within our model of partially screened gap we derived the simple formula relating LxL_x and P^3\hat{P}_3, and showed that it holds for PSRs B0943++10 and B1133+16, which are the only two pulsars in which both LxL_x and P^3\hat{P}_3 are presently known.Comment: 4 page

    Wave Excitation in Disks Around Rotating Magnetic Stars

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    The accretion disk around a rotating magnetic star (neutron star, white dwarf or T Tauri star) is subjected to periodic vertical magnetic forces from the star, with the forcing frequency equal to the stellar spin frequency or twice the spin frequency. This gives rise bending waves in the disk that may influence the variabilities of the system. We study the excitation, propagation and dissipation of these waves using a hydrodynamical model coupled with a generic model description of the magnetic forces. The m=1m=1 bending waves are excited at the Lindblad/vertical resonance, and propagate either to larger radii or inward toward the corotation resonance where dissipation takes place. While the resonant torque is negligible compared to the accretion torque, the wave nevertheless may reach appreciable amplitude and can cause or modulate flux variabilities from the system. We discuss applications of our result to the observed quasi-periodic oscillations from various systems, in particular neutron star low-mass X-ray binaries.Comment: Small changes/clarifications. To be published in ApJ, Aug.20,2008 issu

    You are how you travel: A multi-task learning framework for Geodemographic inference using transit smart card data

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    Geodemographics, providing the information of population's characteristics in the regions on a geographical basis, is of immense importance in urban studies, public policy-making, social research and business, among others. Such data, however, are difficult to collect from the public, which is usually done via census, with a low update frequency. In urban areas, with the increasing prevalence of public transit equipped with automated fare payment systems, researchers can collect massive transit smart card (SC) data from a large population. The SC data record human daily activities at an individual level with high spatial and temporal resolutions. It can reveal frequent activity areas (e.g., residential areas) and travel behaviours of passengers that are intimately intertwined with personal interests and characteristics. This provides new opportunities for geodemographic study. This paper seeks to develop a framework to infer travellers' demographics (such as age, income level and car ownership, et al.) and their residential areas for geodemographic mapping using SC data with a household survey. We first use a decision tree diagram to detect passengers' residential areas. We then represent each individual's spatio-temporal activity pattern derived from multi-week SC data as a 2D image. Leveraging this representation, a multi-task convolutional neural network (CNN) is employed to predict multiple demographics of individuals from the images. Combing the demographics and locations of their residence, geodemographic information is further obtained. The methodology is applied to a large-scale SC dataset provided by Transport for London. Results provide new insights in understanding the relationship between human activity patterns and demographics. To the best of our knowledge, this is the first attempt to infer geodemographics by using the SC data

    On the blow-up phenomenon for a generalized Davey-Stewartson system

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    The blow-up solutions of the Cauchy problem for a generalized Davey–Stewartson system, which models the wave propagation in a bulk medium made of an elastic material with coupled stresses, are investigated. The mass concentration is established for all the blow-up solutions of the system. The profile of the minimal blow-up solutions as t → T (blow-up time) is discussed in detail in terms of the ground state

    An Exact No Free Lunch Theorem for Community Detection

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    A precondition for a No Free Lunch theorem is evaluation with a loss function which does not assume a priori superiority of some outputs over others. A previous result for community detection by Peel et al. (2017) relies on a mismatch between the loss function and the problem domain. The loss function computes an expectation over only a subset of the universe of possible outputs; thus, it is only asymptotically appropriate with respect to the problem size. By using the correct random model for the problem domain, we provide a stronger, exact No Free Lunch theorem for community detection. The claim generalizes to other set-partitioning tasks including core/periphery separation, kk-clustering, and graph partitioning. Finally, we review the literature of proposed evaluation functions and identify functions which (perhaps with slight modifications) are compatible with an exact No Free Lunch theorem
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