1,738 research outputs found

    Semi-regular continued fractions and an exact formula for the moments of the Minkowski question mark function

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    This paper continues investigations on the integral transforms of the Minkowski question mark function. In this work we finally establish the long-sought formula for the moments, which does not explicitly involve regular continued fractions, though it has a hidden nice interpretation in terms of semi-regular continued fractions. The proof is self-contained and does not rely on previous results by the author.Comment: 8 page

    Expanding the application of cassava value chain technologies through UPoCA project

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    Root and Tuber . IITA TechnologiesCassava has long been expected to play a key role in rural economic growth in Africa, but are we there yet? Although research partnerships have produced elite cassava varieties with 50% more yielding potential and demonstrated technologies to boost processing and marketing of cassava, the sub-sector is constrained by low productivity and marketing dificulties. In DR Congo, Ghana, Malawi and Sierra Leone, for example, cassava value chain actors are yet to respond to 2007 estimated $59 million trade opportunities through substitution of imported wheat lour with locally produced high quality cassava lour. Industrial pull for cassava would also aggravate hunger and poverty if yields do not increase from current national averages of 5 to 19t/ha to more than 25t/ha expected of released varieties under low input agriculture. In 2008, USAID and IITA initiated the project “Unleashing the Power of Cassava in Response to Food Price Crisis (UPOCA) as a multi-country and inter-institutional partnership enabling cassava sub-sectors to realize their full potential in rural economies. UPoCA project covers DR Congo, Ghana, Malawi, Mozambique, Nigeria, Sierra Leone, and Tanzania. UPoCA project draws on prior research results to increase on-farm cassava productivity and value adding processing for markets. By end 2009, small holder beneiciaries associated with 55 partner organizations and 11 agricultural related irms established 306 community cassava stem multiplication sites and root production farms totalling 10,097ha with 58 improved varieties. Through experiential learning at 24 hands-on short-term courses, 345 men and 142 women learnt improved techniques in cassava production, processing, product development, and packaging/labelling and 8 technologies were introduced to rural communities. Seven other papers in this symposium, based on these evolving UPoCA achievements, show that a longer-term cassava research for development partnership platform of this nature will enable cassava sub-sectors to contribute signiicantly to rural economic growth in Africa

    Microstructure and reconstitution of freeze-dried gum Arabic at a range of concentrations and primary drying temperatures

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    Freeze-drying is an energy intensive unit operation used for the production of dehydrated foods, such as instant coffee and dried fruits, and results in high sensorial, nutritional and reconstitution properties of the final products. Understanding the relationships between operating conditions and product quality is essential to design processes that are energy efficient, whilst producing high quality dried foods. In this work, the properties (microstructure and reconstitution) of freeze-dried gum arabic samples (with initial concentrations ranging between 20 and 60% solids by weight) were evaluated. The materials were dried at three different primary drying shelf temperatures, Ts (- 20, - 30 and - 40 ◦C). Sample temperatures recorded throughout freeze-drying were close to the pre-set Ts, with the exception of the 60% initial concentration system, where the sample was hotter than the shelf by 10–15 ◦C, in particular on increasing Ts. This was attributed to a combination of local temperature and pressure conditions that may have resulted in partial melting of the material. For the 20–50% systems, the properties of the freeze-dried materials were mainly affected by the initial concentration of the system, with increasing initial concentration generally resulting in lower porosities (ranging between 20 and 40%) and higher reconstitution times (ranging between 0.5 and 10min for 95% reconstitution). Pores were generally needle-shaped and <200 μm. Large (200–1800 μm), circular pores were observed in high initial concentration systems, and they were dominant in the microstructure of the freeze-dried 60% sample. The presence of these large bubbles was linked to the partial melting of the material, which enabled its expansion and puffing. For the 60% system, primary drying temperature had a profound effect on the properties of the freeze-dried solid, with samples dried at higher temperature showing higher porosity (e.g. 60–70% for Ts = -¬¬ 20◦C) and faster reconstitution rates (e.g. 3min for 95% reconstitution at Ts = - 20◦C). Overall, this study demonstrates the significance of formulation and shelf temperature on the porous structure of freeze-dried samples, which directly influences product performance

    Correlations for the orthogonal-unitary and symplectic-unitary transitions at the hard and soft edges

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    For the orthogonal-unitary and symplectic-unitary transitions in random matrix theory, the general parameter dependent distribution between two sets of eigenvalues with two different parameter values can be expressed as a quaternion determinant. For the parameter dependent Gaussian and Laguerre ensembles the matrix elements of the determinant are expressed in terms of corresponding skew-orthogonal polynomials, and their limiting value for infinite matrix dimension are computed in the vicinity of the soft and hard edges respectively. A connection formula relating the distributions at the hard and soft edge is obtained, and a universal asymptotic behaviour of the two point correlation is identified.Comment: 37 pgs., 1fi

    Efficacy of pimobendan in the prevention of congestive heart failure or sudden death in doberman pinschers with preclinical dilated cardiomyopathy (the PROTECT study)

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    &lt;p&gt;Background: The benefit of pimobendan in delaying the progression of preclinical dilated cardiomyopathy (DCM) in Dobermans is not reported.&lt;/p&gt; &lt;p&gt;Hypothesis: That chronic oral administration of pimobendan to Dobermans with preclinical DCM will delay the onset of CHF or sudden death and improve survival.&lt;/p&gt; &lt;p&gt;Animals: Seventy-six client-owned Dobermans recruited at 10 centers in the UK and North America.&lt;/p&gt; &lt;p&gt;Methods: The trial was a randomized, blinded, placebo-controlled, parallel group multicenter study. Dogs were allocated in a 1:1 ratio to receive pimobendan (Vetmedin capsules) or visually identical placebo.&lt;/p&gt; &lt;p&gt;The composite primary endpoint was prospectively defined as either onset of CHF or sudden death. Time to death from all causes was a secondary endpoint.&lt;/p&gt; &lt;p&gt;Results: The proportion of dogs reaching the primary endpoint was not significantly different between groups (P = .1). The median time to the primary endpoint (onset of CHF or sudden death) was significantly longer in the pimobendan (718 days, IQR 441–1152 days) versus the placebo group (441 days, IQR 151–641 days) (log-rank P = 0.0088). The median survival time was significantly longer in the pimobendan (623 days, IQR 491–1531 days) versus the placebo group (466 days, IQR 236–710 days) (log-rank P = .034).&lt;/p&gt; &lt;p&gt;Conclusion and Clinical Importance: The administration of pimobendan to Dobermans with preclinical DCM prolongs the time to the onset of clinical signs and extends survival. Treatment of dogs in the preclinical phase of this common cardiovascular disorder with pimobendan can lead to improved outcome.&lt;/p&gt

    Using X-ray Crystallography, Biophysics, and Functional Assays to Determine the Mechanisms Governing T-cell Receptor Recognition of Cancer Antigens.

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    Human CD8+ cytotoxic T lymphocytes (CTLs) are known to play an important role in tumor control. In order to carry out this function, the cell surface-expressed T-cell receptor (TCR) must functionally recognize human leukocyte antigen (HLA)-restricted tumor-derived peptides (pHLA). However, we and others have shown that most TCRs bind sub-optimally to tumor antigens. Uncovering the molecular mechanisms that define this poor recognition could aid in the development of new targeted therapies that circumnavigate these shortcomings. Indeed, present therapies that lack this molecular understanding have not been universally effective. Here, we describe methods that we commonly employ in the laboratory to determine how the nature of the interaction between TCRs and pHLA governs T-cell functionality. These methods include the generation of soluble TCRs and pHLA and the use of these reagents for X-ray crystallography, biophysical analysis, and antigen-specific T-cell staining with pHLA multimers. Using these approaches and guided by structural analysis, it is possible to modify the interaction between TCRs and pHLA and to then test how these modifications impact T-cell antigen recognition. These findings have already helped to clarify the mechanism of T-cell recognition of a number of cancer antigens and could direct the development of altered peptides and modified TCRs for new cancer therapies

    Neutron Knockout Reactions

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    This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

    Noncolliding Squared Bessel Processes

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    We consider a particle system of the squared Bessel processes with index ν>1\nu > -1 conditioned never to collide with each other, in which if 1<ν<0-1 < \nu < 0 the origin is assumed to be reflecting. When the number of particles is finite, we prove for any fixed initial configuration that this noncolliding diffusion process is determinantal in the sense that any multitime correlation function is given by a determinant with a continuous kernel called the correlation kernel. When the number of particles is infinite, we give sufficient conditions for initial configurations so that the system is well defined. There the process with an infinite number of particles is determinantal and the correlation kernel is expressed using an entire function represented by the Weierstrass canonical product, whose zeros on the positive part of the real axis are given by the particle-positions in the initial configuration. From the class of infinite-particle initial configurations satisfying our conditions, we report one example in detail, which is a fixed configuration such that every point of the square of positive zero of the Bessel function JνJ_{\nu} is occupied by one particle. The process starting from this initial configuration shows a relaxation phenomenon converging to the stationary process, which is determinantal with the extended Bessel kernel, in the long-term limit.Comment: v3: LaTeX2e, 26 pages, no figure, corrections made for publication in J. Stat. Phy
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