2,055 research outputs found

    Splitting up a complex mess: The effectiveness of statistical analysis on delimiting species complexes

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    Recent studies have highlighted a need for more refined tools in species delimitation. This is especially true when considering diversity within species complexes, where members are morphologically similar and traditional tools have thus far failed to provide clearly defined boundaries between species. This project seeks to refine our traditional tools of species delimitation and apply new tools to the challenges created by species complexes. The focus organisms of this study are the anurans of the Limnonectes kuhlii complex. This species complex comprises more than 25 species of stream frogs from Southeast Asia. Traditionally, morphometrics (particularly linear measures) has been the most common way to demonstrate differences between two or more species. Unfortunately, traditional morphological analyses placed members of this group into a single, widely distributed species for nearly 200 years. Recent studies combining genetic, morphological, and bioacoustic tools have been effective in distinguishing and delimiting some, but not all potential species of the L. kuhlii complex. The currently distinguished, yet undescribed, members (candidate species) provide an opportunity to investigate new approaches to morphological character analyses (e.g., geometric morphometrics), and to refine traditional approaches (alternative statistical analyses) used in species delimitation. Geometric morphometrics show statistically significant differences in head shape between candidate species. Statistics provided a refinement of the traditional morphological approaches and revealed a list of potential characters for delimiting the candidate species on Borneo. This study showed the use of Body Length (BL), recommended by Inger (1966), provided the same results as Snout-vent Length. Illustrating that BL should be considered throughout the complex, especially when previous studies have shown SVL between males and females of the same candidate species (or clade). BL may provide further insight to the candidate species on mainland by giving a new outlook on previously used data. Ultimately, this project aims to recognize, delimit, and describe real biological diversity in order to facilitate conservation efforts aimed at protecting these frogs and the habitats that they live in

    Special Lagrangian cones with higher genus links

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    For every odd natural number g=2d+1 we prove the existence of a countably infinite family of special Lagrangian cones in C^3 over a closed Riemann surface of genus g, using a geometric PDE gluing method.Comment: 48 page

    Charge imbalance and Josephson effects in superconductor-normal metal mesoscopic structures

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    We consider a SBSSBS Josephson junction the superconducting electrodes SS of which are in contact with normal metal reservoirs (BB means a barrier). For temperatures near TcT_{c} we calculate an effective critical current Ic∗% I_{c}^{\ast} and the resistance of the system at the currents I<I< Ic∗% I_{c}^{\ast} and I>>Ic∗I>>I_{c}^{\ast}. It is found that the charge imbalance, which arises due to injection of quasiparticles from the NN reservoirs into the SS wire, affects essentially the characteristics of the structure. The effective critical current Ic∗I_{c}^{\ast} is always larger than the critical current IcI_{c} in the absence of the normal reservoirs and increases with decreasing the ratio of the length of the SS wire 2L2L to the charge imbalance relaxation length lQl_{Q}. It is shown that a series of peaks arises on the I−VI-V characteristics due to excitation of the Carlson-Goldman collective modes. We find the position of Shapiro steps which deviates from that given by the Josephson relation.Comment: 12 pages, 4 figures; accepted for publication in Phys. Rev.

    Boundary definition of a multiverse measure

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    We propose to regulate the infinities of eternal inflation by relating a late time cut-off in the bulk to a short distance cut-off on the future boundary. The light-cone time of an event is defined in terms of the volume of its future light-cone on the boundary. We seek an intrinsic definition of boundary volumes that makes no reference to bulk structures. This requires taming the fractal geometry of the future boundary, and lifting the ambiguity of the conformal factor. We propose to work in the conformal frame in which the boundary Ricci scalar is constant. We explore this proposal in the FRW approximation for bubble universes. Remarkably, we find that the future boundary becomes a round three-sphere, with smooth metric on all scales. Our cut-off yields the same relative probabilities as a previous proposal that defined boundary volumes by projection into the bulk along timelike geodesics. Moreover, it is equivalent to an ensemble of causal patches defined without reference to bulk geodesics. It thus yields a holographically motivated and phenomenologically successful measure for eternal inflation.Comment: 39 pages, 4 figures; v2: minor correction

    On the Lichnerowicz conjecture for CR manifolds with mixed signature

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    We construct examples of nondegenerate CR manifolds with Levi form of signature (p,q)(p,q), 2≤p≤q2\leq p\leq q, which are compact, not locally CR flat, and admit essential CR vector fields. We also construct an example of a noncompact nondegenerate CR manifold with signature (1,n−1)(1,n-1) which is not locally CR flat and admits an essential CR vector fields. These provide counterexamples to the analogue of the Lichnerowicz conjecture for CR manifolds with mixed signature.Comment: 7 page

    Development of use of an Operational Procedure Information System (OPIS) for future space missions

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    A MS-Windows based electronic procedure system, called OPIS (Operational Procedure Information System), was developed. The system consists of two parts, the editor, for 'writing' the procedure and the notepad application, for the usage of the procedures by the crew during training and flight. The system is based on standardized, structured procedure format and language. It allows the embedding of sketches, photos, animated graphics and video sequences and the access to off-nominal procedures by linkage to an appropriate database. The system facilitates the work with procedures of different degrees of detail, depending on the training status of the crew. The development of a 'language module' for the automatic translation of the procedures, for example into Russian, is planned

    A simple remark on a flat projective morphism with a Calabi-Yau fiber

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    If a K3 surface is a fiber of a flat projective morphisms over a connected noetherian scheme over the complex number field, then any smooth connected fiber is also a K3 surface. Observing this, Professor Nam-Hoon Lee asked if the same is true for higher dimensional Calabi-Yau fibers. We shall give an explicit negative answer to his question as well as a proof of his initial observation.Comment: 8 pages, main theorem is generalized, one more remark is added, mis-calculation and typos are corrected etc

    Vacuum Spacetimes with Future Trapped Surfaces

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    In this article we show that one can construct initial data for the Einstein equations which satisfy the vacuum constraints. This initial data is defined on a manifold with topology R3R^3 with a regular center and is asymptotically flat. Further, this initial data will contain an annular region which is foliated by two-surfaces of topology S2S^2. These two-surfaces are future trapped in the language of Penrose. The Penrose singularity theorem guarantees that the vacuum spacetime which evolves from this initial data is future null incomplete.Comment: 19 page
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