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Search Results: 1 - 10 of 208629 matches for " Grecebio Jonathan D. Alejandro "
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Molecular Phylogeny of the Philippine Endemic Genus Antherostele Bremek. (Rubiaceae) Inferred from ITS Data (nrDNA) and Its Conservation Status  [PDF]
Jasper John A. Obico, Grecebio Jonathan D. Alejandro
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.310169
Abstract: Antherostele Bremek. is an understudied genus of Rubiaceae endemic to the Philippines formerly comprising four species of shrubs or small trees distributed in Luzon and Visayas. In this first molecular study of the genus, the ITS (nrDNA) was utilized to determine the monophyly of Antherostele, reconstruct its phylogeny, and resolve its placement in Rubiaceae. Furthermore, an update on the assessment of its conservation status of the included species in the genus was done. Antherostele is monophyletic and is nested within the tribe Urophylleae of subfamily Rubioideae which confirms its segregation from Urophyllum and its placement within Urophylleae as proposed by earlier authors based on morphology. However, the relationships of Urophylleae members remain unresolved. Antherostele is united by reflexed corolla, hairs on upper side of the corolla lobes and syngenesious stamens. The montane A. luzoniensis with small leaves is found to be sister to the rest of Antherostele species. Antherostele is hypothesized to originate from montane regions and diversified by forming larger leaves following dispersal to the shaded forest understory. From the five species of Antherostele currently recognized in the study, two are endangered (A. banahaensis, A. grandistipula) and three are critically endangered including a new species (A. callophylla, A. luzoniensis, A. sp. nov.) following the criteria of IUCN.
Applying Fishers' Ecological Knowledge to Construct Past and Future Lobster Stocks in the Juan Fernández Archipelago, Chile
Tyler D. Eddy,Jonathan P. A. Gardner,Alejandro Pérez-Matus
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013670
Abstract: Over-exploited fisheries are a common feature of the modern world and a range of solutions including area closures (marine reserves; MRs), effort reduction, gear changes, ecosystem-based management, incentives and co-management have been suggested as techniques to rebuild over-fished populations. Historic accounts of lobster (Jasus frontalis) on the Chilean Juan Fernández Archipelago indicate a high abundance at all depths (intertidal to approximately 165 m), but presently lobsters are found almost exclusively in deeper regions of their natural distribution. Fishers' ecological knowledge (FEK) tells a story of serial depletion in lobster abundance at fishing grounds located closest to the fishing port with an associated decline in catch per unit effort (CPUE) throughout recent history. We have re-constructed baselines of lobster biomass throughout human history on the archipelago using historic data, the fishery catch record and FEK to permit examination of the potential effects of MRs, effort reduction and co-management (stewardship of catch) to restore stocks. We employed a bioeconomic model using FEK, fishery catch and effort data, underwater survey information, predicted population growth and response to MR protection (no-take) to explore different management strategies and their trade-offs to restore stocks and improve catches. Our findings indicate that increased stewardship of catch coupled with 30% area closure (MR) provides the best option to reconstruct historic baselines. Based on model predictions, continued exploitation under the current management scheme is highly influenced by annual fluctuations and unsustainable. We propose a community-based co-management program to implement a MR in order to rebuild the lobster population while also providing conservation protection for marine species endemic to the Archipelago.
Y-Stenting for Bifurcation Aneurysm Coil Embolization: What is the Risk?
Alejandro M. Spiotta,Jonathan Lena,M. Imran Chaudry,Raymond D. Turner,Aquilla S. Turk
Stroke Research and Treatment , 2014, DOI: 10.1155/2014/762389
Abstract: The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms has been accepted as an alternative to clip reconstruction of a select subset of challenging aneurysms. We review the risks associated with Y-stenting, including its procedural complication rates, angiographic occlusion rates, rerupture, and retreatment rates. 1. Introduction Since the International Symptomatic Aneurysm Trial (ISAT) and the Barrow Ruptured Aneurysm Trial (BRAT) firmly established endovascular therapy as a valid method for treating intracranial aneurysms, development of new techniques has broadened the scope of practice to allow for the treatment of geometrically complex aneurysms. Until the introduction and widespread adoption of adjuncts to endovascular coil embolization, complex wide-necked bifurcation aneurysms had classically been treated with microsurgical clip reconstruction. Advances in endovascular techniques including balloon remodeling as well as the use of stents have allowed more of these challenging aneurysms to be treated with coil embolization. The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms was first described by Chow et al. in 2004 [1]. Since that time many reports have been published demonstrating low morbidity and mortality rates associated with Y-stenting [1–14] and it has been accepted as a safe and reasonable alternative to clip reconstruction of a select subset of challenging aneurysms. But what exactly are the risks associated with Y-stenting? To address this question a thorough understanding of the technical aspects of the procedure as well as the available reported rates of complications is required. 2. Stent Assisted Coiling The technique of stent assisted coiling in the clinical setting was first described in 1997 [15] Soon after, the availability of new flexible, self-expanding intracranial stents allowed for increasing application of this technique and observation of its benefits. Stents have been quickly adopted as promising adjuncts with potential mechanical, hemodynamic, and biologic properties, imparting an advantage over coil embolization alone [15]. Stent deployment provides mechanical support to prevent coil prolapse, may serve as a conduit to divert flow, and provides a scaffold for endothelial growth and vessel healing [15–17]. In addition, an implanted stent may incur subtle changes in the parent vessel-aneurysm geometry, imparting significant hemodynamic alterations which change the inflow
Measurements and confluence in quantum lambda calculi with explicit qubits
Alejandro Díaz-Caro,Pablo Arrighi,Manuel Gadella,Jonathan Grattage
Physics , 2008, DOI: 10.1016/j.entcs.2011.01.006
Abstract: This paper demonstrates how to add a measurement operator to quantum lambda-calculi. A proof of the consistency of the semantics is given through a proof of confluence presented in a sufficiently general way to allow this technique to be used for other languages. The method described here may be applied to probabilistic rewrite systems in general, and to add measurement to more complex languages such as QML or Lineal, which is the subject of further research.
On the Cohomology of Central Frattini Extensions
Alejandro Adem,Jonathan Pakianathan
Mathematics , 2000,
Abstract: We use topological methods to compute the mod p cohomology of certain p-groups. More precisely we look at central Frattini extensions of elementary abelian by elementary abelian groups such that their defining k-invariants span the entire image of the Bockstein. We show that if p is sufficiently large, then the mod p cohomology of the extension can be explicitly computed as an algebra.
The Summation of One Class of Infinite Series  [PDF]
Jonathan D. Weiss
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.517269
Abstract: This paper presents closed-form expressions for the series, \"\", where the sum is from n = 1 to n = ∞. These expressions were obtained by recasting the series in a different form, followed by the use of certain relationships involving the elliptical nome. Among the values of x for which these expressions can be obtained are of the form: \"\" and \"\", where l is an integer between ∞ and ∞. The values of λ include 1,\"\",\"\"and 3. Examples of closed-form expressions obtained in this manner are first presented for \"\", \"\", \"\", and \"\". Additional examples are then presented for \"\", \"\", \"\", and \"\". This undertaking was prompted by the author’s work on an electrostatics boundary-value problem related to the van der Pauw measurement technique of electrical resistivity. The presence of this series for x = \"\" in the solution of that problem and its absence from any compendium of infinite series that he consulted led to this work.
The Gravitational Attraction between Hemispherical Masses  [PDF]
Jonathan D. Weiss
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.86064
Abstract: This paper is a study of the gravitational attraction between two uniform hemispherical masses aligned such that the pair is cylindrically symmetric. Three variations are considered: flat side to flat side, curved side to curved side, and flat side to curved side. Expressions for the second and third variation are derived from the first, with the use of superposition and the well-known gravitational behavior of a spherical mass as equivalent to a point mass at its center. The study covers two masses of equal diameter and of different diameters, such that one is four times that of the other. Calculations are done for separations from zero to fifty times the radius of the larger of the two, which is effectively the asymptotic limit. It is demonstrated that at any separation, the force can be expressed as if the two hemispheres were point masses separated by a certain distance. Expressions for that distance and the location of the (fictitious) point masses within each hemisphere are presented. Unlike the case of two spherical masses, the location within their respective hemisphere is not necessarily the same for each point and both are dependent upon the separation between the two hemispheres. The calculation for the first variation is done in two ways. The first is a “brute force” multi-dimensional integral with the help of Wolfram Mathematica. The second is an axial expansion for the potential modified for off-axis locations by Legendre polynomials. With only a few terms in the expansion, the results of the second method are in extremely good agreement with those of the first. Finally, an interesting application to a split earth is presented.
Certain Aspects of the Gravitational Field of a Disk  [PDF]
Jonathan D. Weiss
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.912089
Abstract:
There are at least two reasons why one would study the gravitational field of a disk. The first is that many astronomical objects, such as spiral galaxies like the Milky Way, are disk-like. The second is that the field of a disk is interesting, particularly when compared to that of a spherical, or near-spherical, object, which is much easier to analyze because of its high degree of symmetry. It is hoped that this study will augment previous work on this subject. The aspects presented in this paper are as follows: 1) both the radial and vertical gravitational fields of a thin disk within the plane of the disk and above it; 2) a comparison of some of the field results obtained by Lass and Blitzer (1983) involving elliptic integrals to those obtained by a standard numerical integration, now available online, and separately through the use of Legendre polynomials; 3) the logarithmic divergence of the radial field at the edge of a thin disk; 4) the fields in the plane of a disk containing a central hole, particularly within the hole, such as the rings of Saturn; 5) circular orbits within the plane of a single disk and half way between two disks, and their stability; 6) the escape velocity at a point within the Milky Way, particularly at the position of the solar system and without any added, or subtracted, orbital effects around the galactic center; and 7) the radial field at the circular edge of a disk of finite thickness.
Role Expansion: Implications of the Security Role Expanding into the EHS Function  [PDF]
Wanda D. Minnick, Jonathan D. Cunkelman
Open Journal of Safety Science and Technology (OJSST) , 2015, DOI: 10.4236/ojsst.2015.53010
Abstract: The purpose of this study was to explore the perception of safety professionals regarding the expansion of their role into security functions. One hundred eleven returned surveys from practicing safety professionals in the manufacturing, oil and gas, and construction industries were examined. Fifty seven percent of respondents agree with role expansion into security and twenty three percent of participants do not. Thematic patterns emerged from their comments and are provided. The remaining twenty percent of respondents fell into a category of “it depends” and the provided reasons suggest other variables that could have influence. A Chi square test for independence indicated that role expansion is independent of industry type; suggesting there is agreement for role expansion into security functions regardless of industry type. Another primary finding is that although the majority of safety professionals agree with role expansion, security coursework is currently not required in a review of accredited occupational safety and health program curricula. This suggests recent graduates may not be formerly prepared for the security elements of their role and should seek or be offered additional training.
Black hole entropy and SU(2) Chern-Simons theory
Jonathan Engle,Karim Noui,Alejandro Perez
Physics , 2009, DOI: 10.1103/PhysRevLett.105.031302
Abstract: Black holes in equilibrium can be defined locally in terms of the so-called isolated horizon boundary condition given on a null surface representing the event horizon. We show that this boundary condition can be treated in a manifestly SU(2) invariant manner. Upon quantization, state counting is expressed in terms of the dimension of Chern-Simons Hilbert spaces on a sphere with marked points. Moreover, the counting can be mapped to counting the number of SU(2) intertwiners compatible with the spins that label the defects. The resulting BH entropy is proportional to a_H with logarithmic corrections \Delta S=-3/2 \log a_H. Our treatment from first principles completely settles previous controversies concerning the counting of states.
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