Search results for "Zone"
showing 10 items of 2029 documents
Characterizing a hybrid zone between a cryptic species pair of freshwater snails.
2015
Characterizing hybrid zones and their dynamics is a central goal in evolutionary biology, but this is particularly challenging for morphologically cryptic species. The lack of conspicuous divergence between parental types means intermediate hybrid forms often go undetected. We aimed to detect and characterize a suspected hybrid zone between a pair of morphologically cryptic lineages of the freshwater snail, Radix. We sampled Radix from across a contact zone between two mitochondrial lineages (Radix balthica and an undescribed lineage termed 'MOTU3') and detected admixture between two nuclear genotype clusters, which were significantly but not categorically associated with the mitochondrial …
Pre- and post-mating reproductive barriers drive divergence of five sympatric species of Naryciinae moths (Lepidoptera: Psychidae)
2014
The biological species concept suggests that species can be separated on the basis of reproductive isolation. However, because natural interbreeding capabilities are often unknown, differences in morphology are generally used to separate species. Alternatively, genetic dissimilarity is used to separate morphologically similar species. Many genetic markers, including the maternally inherited mitochondrial cytochrome oxidase I sequence, cannot show interbreeding and therefore species status of groups may remain unresolved. In species of the genera Dahlica and Siederia (Lepidoptera: Psychidae: Naryciinae) the lack of morphological distinction and unknown interbreeding has led to unclear and un…
Isolation, Long-Term Expansion, and Differentiation of Murine Neural Stem Cells
2014
Stem cells are capable of extensive self-renewal while preserving the ability to generate cell progeny that can differentiate into different cell types. Here, we describe some methods for the isolation of neural stem cells (NSCs) from the adult murine subependymal zone (SEZ), their extensive culturing and the assessment of their full developmental potential, particularly with respect to their differentiation capacity. The procedure includes chemically defined conditions such as absence of serum and addition of specific growth factors, in which differentiated cells die and are rapidly eliminated from the culture. In contrast, undifferentiated precursors become hypertrophic and proliferate, f…
Host−Guest Interactions between β-Cyclodextrin and the (Z)-Phenylhydrazone of 3-Benzoyl-5-phenyl-1,2,4-oxadiazole: The First Kinetic Study of a Ring…
2002
The effect of beta-cyclodextrin (beta-CD) on the mononuclear heterocyclic rearrangement of the (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1) in aqueous borate buffer at pH = 9.6 has been analyzed at temperatures ranging from 293.15 to 313.15 K. The trend of the absorption spectra of 1 as a function of time has been accounted for with the formation of two different 1:1 complexes between beta-CD and 1, the first, "unreactive" complex being formed faster than the "reactive" one. The occurrence of negative activation enthalpy values for the studied interconversion evidences the kinetic relevance of inclusion processes. Computational models elaborated using the MM2 molecular mec…
Single-Hemisphere Photoelectron Momentum Microscope With Time-of-Flight Recording
2020
Photoelectron momentum microscopy is an emerging powerful method for angle-resolved photoelectron spectroscopy (ARPES), especially in combination with imaging spin filters. These instruments record kx-ky images, typically exceeding a full Brillouin zone. As energy filters double-hemispherical or time-of-flight (ToF) devices are in use. Here we present a new approach for momentum mapping of the full half-space, based on a single hemispherical analyzer (path radius 225 mm). Excitation by an unfocused He lamp yielded an energy resolution of 7.7 meV. The performance is demonstrated by k-imaging of quantum-well states in Au and Xe multilayers. The alpha-square-aberration term (alpha: entrance an…
Splenic marginal zone lymphoma with or without villous lymphocytes
2004
The Integruppo Italiano Linfomi (IIL) carried out a study to assess the outcomes of splenic marginal zone lymphoma and to identify prognostic factors in 309 patients. The 5-year cause-specific survival (CSS) rate was 76%. In univariate analysis, the parameters predictive of shorter CSS were hemoglobin levels below 12 g/dL (P < .001), albumin levels below 3.5 g/dL (P = .001), International Prognostic Index (IPI) scores of 2 to 3 (P < .001), lactate dehydrogenase (LDH) levels above normal (P < .001), age older than 60 years (P = .01), platelet counts below 100,000/microL (P = .04), HbsAg-positivity (P = .01), and no splenectomy at diagnosis (P = .006). Values that maintained a negative influe…
Responses of Young Peach Trees to Root Confinement
1994
Rooted cuttings of Nemaguard peach [Prunus persica (L.) Batsch.] were grown in 0.18-, 0.36-, 0.90-, and 2.40-liter containers for 16 weeks to study the influence of root confinement on growth, gas exchange, water uptake, and leaf carbohydrate and nutrient content. An automatic nutrient-solution dispensing system was used to ensure uniform fertility among treatments and to prevent drought stress. Leaf area and stem length were reduced by root confinement 6 to 7 weeks after transplanting, and differences among treatments increased throughout the experiment. Final tree dry weights were reduced by 51% over a 13-fold reduction in rooting volume, but dry weight partitioning was largely unaffected…
An Efficient Implementation of Distributed Routing Algorithms for NoCs
2008
The design of NoCs for multi-core chips introduces new design constraints like power consumption, area, and ultra low latencies. Although 2D meshes are preferred, heterogeneous blocks, fabrication faults, reliability issues, and chip virtualization may lead to the need of irregular topologies or regions. In this situation, efficient routing becomes a challenge. Although the use of routing tables at switches is flexible, it does not scale in terms of latency and area due to its memory requirements. LBDR (logic-based distributed routing) is proposed as a new routing method that removes the need of using routing tables at all. LBDR enables the implementation of many routing algorithms on most …
Circuit-Elimination based Link-State Routing in Mobile Ad-hoc Networks
2007
Circuit-elimination based connected dominating set formation is an efficient technique for reducing routing overhead in mobile ad hoc networks. In this paper, we propose a new message dissemination algorithm which utilizes such techniques to reduce the number of nodes that generate or forward link state advertisements in link state routing protocols. Simulation results with both static and dynamic network topologies demonstrate the potential of the proposed algorithm to reduce routing overhead, compared with a benchmark link state routing protocol, OLSR.
Ornstein-Zernike equation and Percus-Yevick theory for molecular crystals
2004
We derive the Ornstein-Zernike equation for molecular crystals of axially symmetric particles and apply the Percus-Yevick approximation to this system. The one-particle orientational distribution function has a nontrivial dependence on the orientation and is needed as an input. Despite some differences, the Ornstein-Zernike equation for molecular crystals has a similar structure as for liquids. We solve both equations for hard ellipsoids on a sc lattice. Compared to molecular liquids, the tensorial orientational correlators exhibit less structure. However, depending on the lengths a and b of the rotation axis and the perpendicular axes of the ellipsoids, different behavior is found. For obl…