23,450 research outputs found

    Certified Roundoff Error Bounds Using Semidefinite Programming.

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    Roundoff errors cannot be avoided when implementing numerical programs with finite precision. The ability to reason about rounding is especially important if one wants to explore a range of potential representations, for instance for FPGAs or custom hardware implementation. This problem becomes challenging when the program does not employ solely linear operations as non-linearities are inherent to many interesting computational problems in real-world applications. Existing solutions to reasoning are limited in the presence of nonlinear correlations between variables, leading to either imprecise bounds or high analysis time. Furthermore, while it is easy to implement a straightforward method such as interval arithmetic, sophisticated techniques are less straightforward to implement in a formal setting. Thus there is a need for methods which output certificates that can be formally validated inside a proof assistant. We present a framework to provide upper bounds on absolute roundoff errors. This framework is based on optimization techniques employing semidefinite programming and sums of squares certificates, which can be formally checked inside the Coq theorem prover. Our tool covers a wide range of nonlinear programs, including polynomials and transcendental operations as well as conditional statements. We illustrate the efficiency and precision of this tool on non-trivial programs coming from biology, optimization and space control. Our tool produces more precise error bounds for 37 percent of all programs and yields better performance in 73 percent of all programs

    SOT163-1

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    2. Features and benefits The 74HC541; 74HCT541 is an octal non-inverting buffer/line driver with 3-state outputs. The device features two output enables (OE1 and OE2). A HIGH on OEn causes the outputs to assume a high-impedance OFF-state. Inputs include clamp diodes that enable the use of current limiting resistors to interface inputs to voltages in excess of VCC. Non-Inverting output

    Caveolin-1 is a risk factor for postsurgery metastasis in preclinical melanoma models

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    Melanomas are highly lethal skin tumours that are frequently treated by surgical resection. However, the efficacy of such procedures is often limited by tumour recurrence and metastasis. Caveolin-1 (CAV1) has been attributed roles as a tumour suppressor, although in late-stage tumours, its presence is associated with enhanced metastasis. The expression of this protein in human melanoma development and particularly how the presence of CAV1 affects metastasis after surgery has not been defined. CAV1 expression in human melanocytes and melanomas increases with disease progression and is highest in metastatic melanomas. The effect of increased CAV1 expression can then be evaluated using B16F10 murine melanoma cells injected into syngenic immunocompetent C57BL/6 mice or human A375 melanoma cells injected into immunodeficient B6Rag1−/− mice. Augmented CAV1 expression suppresses tumour formation upon a subcutaneous injection, but enhances lung metastasis of cells injected into the tail vein in both models. A procedure was initially developed using B16F10 melanoma cells in C57BL/6 mice to mimic better the situation in patients undergoing surgery. Subcutaneous tumours of a defined size were removed surgically and local tumour recurrence and lung metastasis were evaluated after another 14 days. In this postsurgery setting, CAV1 presence in B16F10 melanomas favoured metastasis to the lung, although tumour suppression at the initial site was still evident. Similar results were obtained when evaluating A375 cells in B6Rag1−/− mice. These results implicate CAV1 expression in melanomas as a marker of poor prognosis for patients undergoing surgery as CAV1 expression promotes experimental lung metastasis in two different preclinical models

    Analyzing Digital Image by Deep Learning for Melanoma Diagnosis

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    Image classi cation is an important task in many medical applications, in order to achieve an adequate diagnostic of di erent le- sions. Melanoma is a frequent kind of skin cancer, which most of them can be detected by visual exploration. Heterogeneity and database size are the most important di culties to overcome in order to obtain a good classi cation performance. In this work, a deep learning based method for accurate classi cation of wound regions is proposed. Raw images are fed into a Convolutional Neural Network (CNN) producing a probability of being a melanoma or a non-melanoma. Alexnet and GoogLeNet were used due to their well-known e ectiveness. Moreover, data augmentation was used to increase the number of input images. Experiments show that the compared models can achieve high performance in terms of mean ac- curacy with very few data and without any preprocessing.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Asphyxia neonatorum - assessment of the infant at birth

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    Asphyxia neonatorum is defined as failure of a newborn infant to establish sustained respiration after its complete delivery. In 206 asphyxiated infants reviewed, details of the Apgar scores,  time to sustained respiration and resuscitation required, were documented. The value of each of these observations, as well as that of the heart rate and acid-base status after birth, is assessed. From the findings definite recommendations for the routine assessment of the infant at birth are made.S. Afr. Med. J., 48, 2139 (1974)

    Relative Therapeutic Efficacy of the Treadmill and Step Bench in Gait Rehabilitation of Hemiparetic Stroke Patients

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    The aim of this research is to compare the efficacy of treadmill and step bench exercises in hemiparetic gait rehabilitation. Previous studies have supported the use of treadmill and step bench exercises in gait rehabilitation. Nineteen patients were recruited for an 8-week, 2-group quasi-experimental study which was conducted at the Aminu Kano Teaching Hospital. The patients were randomly distributed into 2 groups: A (step bench exercise) and B (treadmill). Groups A and B had 9 and 10 participants respectively. The mean age of the participants in group A was 47.78 + 8.17 years, while that of participants in group B was 46.9 + 7.11 years. Data collected on cadence, stride length, stride width, step length, stride velocity and foot angle before treatment at the 4th and 8th weeks of treatment were analysed using inferential statistics. There was a significant difference (p < 0.05) in the pre-treatment and post-treatment scores in both groups. Comparison of the post-treatment mean scores of the 2 groups was made and the t-values for cadence, stride length, step length, stride width, stride velocity and foot angle were 1.18, -0.91,-0.86, 0.78,1.19 and 0.01, respectively, after analysis was carried out using the unpaired t test. The results showed no significant difference in the mean scores of the measured gait parameters for the groups (p>0.05). It was concluded that hemiparetic stroke patients will benefit from both rehabilitation protocols, and that neither rehabilitation protocol is superior to the other

    Mechanisms of flame spread and burnout in large enclosure fires

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    Knowledge of the first principles defining fire behaviour in large enclosures remains limited despite their common use in modern tall buildings. The evolution of a fire in large enclosures can be defined by the relationship between the flame front and burnout velocities (VS/VBO). This relationship can be classified into three distinct fire spread modes being Mode 1 (VS/VBO → ∞), Mode 2 (VS/VBO > 1), and Mode 3 (VS/VBO ≈ 1). The mechanisms governing flame spread and burnout are investigated using four full-scale enclosure fire experiments with high porosity wood cribs with similar enclosure geometries. Flame and burnout front positions and velocities are estimated using video data. Velocities are affected by the heat feedback from the enclosure and smoke layer to the fuel. The spread velocity shows two regimes, a minimum external heat flux above which there is surface spread (q''s,min) and a heat flux that defines the onset of very rapid flame spread ((q''rs,crit)). A phenomenological model is developed to help identify the underlying mechanisms controlling the transition between the different spread modes. Both the model and data show that for wood cribs, the dependence of the burnout front velocity to the external radiation is weak, whereas the dependence of the flame spread velocity to the external and flame heat flux is strong. A transition from Mode 3 (VS/VBO ≈ 1) to Mode 2 (VS/VBO > 1) occurs with increasing external heat fluxes above q''s,min. The transition to Mode 1 (VS/VBO → ∞) is further defined once (q''rs,crit) is attained due to a sudden increase in the flame heat flux by changing the ventilation condition, or by significant increases in the external heat flux from the enclosure

    Robust and Biocompatible Functionalization of ZnS Nanoparticles by Catechol-Bearing Poly(2-Methyl-2-Oxazoline)s.

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    Zinc sulfide (ZnS) nanoparticles (NPs) are particularly interesting materials for their electronic and luminescent properties. Unfortunately, their robust and stable functionalization and stabilization, especially in aqueous media, has represented a challenging and not yet completely accomplished task. In this work, we report the synthesis of colloidally stable, photoluminescent and biocompatible core\u2013polymer shell ZnS and ZnS:Tb NPs by employing a water-in-oil miniemulsion (ME) process combined with surface functionalization via catechol-bearing poly-2-methyl-2-oxazoline (PMOXA) of various molar masses. The strong binding of catechol anchors to the metal cations of the ZnS surface, coupled with the high stability of PMOXA against chemical degradation, enable the formation of suspensions presenting excellent colloidal stability. This feature, combined with the assessed photoluminescence and biocompatibility, make these hybrid NPs suitable for optical bioimaging

    Dispersion of VOC vapours in the surface treatment workspace: influence of variability in diffusivity, mass transfer and air velocity.

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    Wherever solvents are allowed to disperse into the workspace it is necessary to be able to predict and determine their concentration and the effect of air velocity variations. Models developed to predict dispersion for assessing ventilation efficiency and worker exposure are validated against measured data with varying success. In numerical convection–dispersion models, including computational fluid dynamics methods, the transport coefficient effective diffusivity is used as a turbulence closure parameter and air velocities are used to define convective mass transport. This study shows how transport coefficient values, empirically estimated from airborne volatile organic carbon vapour concentrations from a solvent source, vary in a ventilated workspace. Variability in effective diffusivity values demonstrates non-Fickian dispersion from the source along the length of a one-dimensional axis. An important finding was that a correlation between air velocity and vapour transport data was not found. This suggests that air velocity should not be used a priori to represent mass transport in the determination of vapour dispersion in the workplace

    A new zooarchaeological application for geometric morphometric methods: Distinguishing Ovis aries morphotypes to address connectivity and mobility of prehistoric Central Asian pastoralists.

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Geometric morphometric methods (GMM), which were developed to characterize the shape and size of biological organisms, have been applied within zooarchaeology over the past decade to address animal domestication processes and to refine morphological criteria to differentiate between taxa. However, there has been limited utilization of these methods to discriminate between populations of the same taxa to challenge and refine other key archaeological issues, such as migration and connectivity in prehistory. Presented here is a novel application of a three-dimensional landmark based geometric morphometric approach to address the nature of long distance trade and connectivity on the prehistoric Silk Road. The similarity of Bronze and Iron Age archaeological cultures along this steppe route has encouraged characterisations of these people as nomads, with highly mobile, integrated, and connected human and animal populations. However, the interconnectedness of domestic animal populations, in particular sheep (Ovis aries), the foundation of this prehistoric pastoral economy, has never been examined. This study utilized geometric morphometric methods to quantify geometric morphometric variance of O. aries astragali between three geographically disparate settlement sites within a single Final Bronze age cultural and chronological context. Significant differences between morphotypes revealed that protracted mobility patterns were unlikely and that while animal exchange may have occurred, it was not pervasive enough to produce a uniform sheep morphotype across central and southeastern Kazakhstan. The result of this new application of geometric morphometric methods challenges models of uniform and undifferentiated long distance mobility and economic connectivity between the peoples of the Silk Road.Fulbright scholarshipFrances Mary Hazen fellowshi
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