3,432 research outputs found

    An apertureless near-field microscope for fluorescence imaging

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    We describe an apertureless near field microscope for imaging fluorescent samples. Optical contrast is generated by exploiting fluorescent quenching near a metallized atomic force microscope tip. This microscope has been used to image fluorescent latex beads with subdiffraction limit resolution. The use of fluorescence allows us to prove that the contrast mechanism is indeed spectroscopic in origin

    In Vivo Magnetic Resonance Imaging Morphometry Measurements of Pulmonary Airspace Enlargement

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    Diffusion-weighted magnetic resonance imaging (MRI) provides unparalleled information and measurements of lung structure and function without the burden of ionizing radiation. In particular, diffusion-weighted MRI provides estimates of airspace enlargement, which is a hallmark characteristic of emphysema. MRI provides a way to measure in vivo mean-linear-intercept (Lm) and this is a promising measurement for clinical evaluation of disease progression in patients with Alpha-1 Antitrypsin Deficiency (AATD) in which airspace enlargement begins early in life. As such, our objective was to evaluate MRI measurements of airspace enlargement in AATD patients and compare these measurements to ex-smokers with chronic obstructive pulmonary disease (COPD) and healthy never-smokers. We compared these measurements with standard clinical measurements provided by spirometry, plethysmography and computed tomography; we also demonstrated that MRI detected differences in disease severity in patients with clinically similar measurements

    Challenges in New Physics searches in top-like events at the LHC

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    The prospects of exploring physics beyond the standard model involving top quarks and top-like signals at the LHC based on Monte Carlo simulations at √s = 14 and 10TeV are reviewed. A special attention is given to results that can be expected for the early LHC running in 2010-2011. Consequently, the first section deals with the implications of having a center-of-mass energy lower than what was simulated, √s = 7TeV, for the first years of the LHC running. This will be done qualitatively by discussing the impact on the cross section of various production processes. Following this discussion, several searches for physics Beyond the standard model that are related to the top quark are described: top-antitop resonances, 4th generation of quarks, top charge, W polarization, anomalous Wtb vertex coupling, top-antitop spin correlation, and flavor changing neutral current. Their order of appearance goes from lower to higher integrated luminosity needed to obtain meaningful results out of each analysis

    М. Ф. ФОН ДІТМАР – ЯСКРАВИЙПРЕДСТАВНИК ГІРНИЧОПРОМИСЛОВОЇ БУРЖУАЗІЇ ПІВДНЯ УКРАЇНИ(ОСТАННЯ ЧВЕРТЬ ХІХ– ПОЧАТОК ХХ СТ.)

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    В статті розглянуто постать відомого підприємця, науковця і суспільного діячаМ. Ф. фон Дітмара, визначено основні напрями його діяльності наПівдні Українив останній чверті ХІХ – на початку ХХ ст.The article considers the person of famous businessman, scientist and social activistM. F. von Ditmar, determines themain directions of his activity in SouthernUkraine in the last quarter ofXIX – the beginning ofXXcenturies

    Efficient rigorous numerics for higher-dimensional PDEs via one-dimensional estimates

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    We present an efficient rigorous computational method which is an extension of the work Analytic Estimates and Rigorous Continuation for Equilibria of Higher-Dimensional PDEs (M. Gameiro and J.-P. Lessard, J. Differential Equations, 249 (2010), pp. 2237-2268). The idea is to generate sharp one-dimensional estimates using interval arithmetic which are then used to produce high-dimensional estimates. These estimates are used to construct the radii polynomials which provide an efficient way of determining a domain on which the contraction mapping theorem is applicable. Computing the equilibria using a finite-dimensional projection, the method verifies that the numerically produced equilibrium for the projection can be used to explicitly define a set which contains a unique equilibrium for the PDE. A new construction of the polynomials is presented where the nonlinearities are bounded by products of one-dimensional estimates as opposed to using FFT with large inputs. It is demonstrated that with this approach it is much cheaper to prove that the numerical output is correct than to recompute at a finer resolution. We apply this method to PDEs defined on three- and four-dimensional spatial domains

    Rigorous computation of smooth branches of equilibria for the three dimensional Cahn-Hilliard equation

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    In this paper, we propose a new general method to compute rigorously global smooth branches of equilibria of higher-dimensional partial differential equations. The theoretical framework is based on a combination of the theory introduced in Global smooth solution curves using rigorous branch following (van den Berg et al., Math. Comput. 79(271):1565-1584, 2010) and in Analytic estimates and rigorous continuation for equilibria of higher-dimensional PDEs (Gameiro and Lessard, J. Diff. Equ. 249(9):2237-2268, 2010). Using this method, one can obtain proofs of existence of global smooth solution curves of equilibria for large (continuous) parameter ranges and about local uniqueness of the solutions on the curve. As an application, we compute several smooth branches of equilibria for the three-dimensional Cahn-Hilliard equation

    Rigorous numerics in floquet theory: Computing stable and unstable bundles of periodic orbits

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    In this paper, a rigorous method to compute Floquet normal forms of fundamental matrix solutions of nonautonomous linear differential equations with periodic coefficients is introduced. The Floquet normal form of a fundamental matrix solution F(t) is a canonical decomposition of the form F(t) = Q(t)eRt, where Q(t) is a real periodic matrix and R is a constant matrix. To rigorously compute the Floquet normal form, the idea is to use the regularity of Q(t) and to simultaneously solve for R and Q(t) with the contraction mapping theorem in a Banach space of rapidly decaying coefficients. The explicit knowledge of R and Q can then be used to construct, in a rigorous computer-assisted way, stable and unstable bundles of periodic orbits of vector fields. The new proposed method does not require rigorous numerical integration of the ODE

    Suicidal ideation in an adolescent clinical sample: Attachment patterns and clinical implications

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    Investigated the relationship between attachment patterns and suicidal ideation in a clinical sample of 116 adolescents (aged 10–17 yrs). Ss were assessed on level of current ideation through self-report questionnaires. Lethality of methods contemplated was also rated on a subset of the sample (16 Ss) who, in addition to endorsing current suicidal ideation, presented a plan on a diagnostic interview. Quality of attachment to caregivers based on a semistructured clinical interview was assessed using K. Bartholomew\u27s (see record 1990-30882-001) 2-dimensional, 4-category model of attachment. Categorical analyses indicated that youth with predominantly fearful or preoccupied attachment were more likely to endorse suicidal ideation than were predominantly secure or dismissing youth. Severity of suicidal ideation was positively correlated with ratings of fearfulness and negatively correlated with ratings on the secure and dismissing patterns. Greater lethality in methods of contemplated suicide was positively correlated with preoccupied tendencies. The importance of attachment theory for understanding the factors underlying suicidal ideation in troubled youth is discussed and implications for therapeutic intervention are presented
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