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Case studies and mathematical models of ecological speciation 3: Ecotype formation in a Swedish snail

Formation of partially reproductively isolated ecotypes in the rough periwinkle, Littorina saxatilis, may be a case of incipient nonallopatric ecological speciation. To better understand the dynamics of ecotype formation, its timescale, driving forces and evolutionary consequences, we developed a spatially explicit, individual-based model incorporating relevant ecological, spatial and mate selecti

Geomagnetic field variations in northern Sweden during the Holocene quantified from varved lake sediments and their implications for cosmogenic nuclide production rates

Palaeomagnetic analyses were conducted on two varved lake-sediment sequences in northern Sweden. The magnetic properties of the sediment sequences are dominated by stable single-domain magnetite with characteristics typical of bacterial magnetosomes. Alternating field demagnetization measurements indicate that the single-domain magnetite is the dominant carrier of a stable natural remanent magneti

Antonymy and negation: the boundedness hypothesis

This paper investigates the interpretation of unbounded (scalar) adjective antonyms with and without negation such as (not) narrow – (not) wide and bounded adjective antonyms with and without negation such as (not) dead – (not) alive as well as their interpretations with approximating degree modifiers, fairly and almost, respectively. The investigation was designed to test the boundedness hypothes

A short-term intervention trial with selenate, selenium-enriched yeast and selenium-enriched milk: effects on oxidative defence regulation

Increased Se intakes have been associated with decreased risk of cancer and CVD. Several mechanisms have been proposed, including antioxidant effects through selenoproteins, induction of carcinogen metabolism and effects on the blood lipid profile. In a 4 x 1 week randomised, double-blind cross-over study, healthy young men supplemented their usual diet with selenate, Se-enriched yeast, Se-enriche

Translocation-excision-deletion-amplification mechanism leading to nonsyntenic coamplification of MYC and ATBF1

Despite oncogene amplification being a characteristic of many tumor types, the mechanisms leading to amplicon formation have remained largely unresolved. In this study, we used a combinatorial approach of fluorescence in situ hybridization and single-nucleotide polymorphism chip gene copy number analyses to unravel the mechanism leading to nonsyntenic coamplification of MYC and ATBF1 in SJNB-12 ce

Production of tissue factor by pancreatic islet cells as a trigger of detrimental thrombotic reactions in clinical islet transplantation

Background Intraportal transplantation of pancreatic islets offers improved glycaemic control and insulin independence in type 1 diabetes mellitus, but intraportal thrombosis remains a possible complication. The thrombotic reaction may explain why graft loss occurs and islets from more than one donor are needed, since contact between human islets and ABO-compatible blood in vitro triggers a thromb

CCL25/CCR9 promotes the induction and function of CD103 on intestinal intraepithelial lymphocytes.

The integrin CD103 and the chemokine receptor CCR9 are co-expressed on small intestinal CD8+ intraepithelial lymphocytes (IEL), naïve murine CD8+ T cells and by a small population of effector/memory CD8+ T cells, indicating a potential role for CCR9 in regulating CD103 expression and function. Here, we demonstrate that CD103, in contrast to CCR9, is down-regulated on CD8+ T cells following their a

Habitat fragmentation and the structure of genetic diversity within disjunct isolates of Anthericum ramosum L. (Anthericaceae) in Scandinavia

The lilioid herb, Anthericum ramosum, occurs in four geographically-isolated regions (Sjaelland, Skane, Oland and Gotland) in Denmark and southern Sweden. We investigated allozyme variation at nine polymorphic loci in A. ramosum from 16 sites (33 populations) in the four regions. There was no clear overall geographic pattern of differentiation between the regions, but the southernmost Gotland and

Distinct requirements for optimal growth and In vitro expansion of human CD34(+)CD38(-) bone marrow long-term culture-initiating cells (LTC-IC), extended LTC-IC, and murine in vivo long-term reconstituting stem cells

Recently, primitive human bone marrow (BM) progenitors supporting hematopoiesis in extended (>60 days) long-term BM cultures were identified. Such extended long-term culture-initiating cells (ELTC-IC) are of the CD34(+)CD38(-) phenotype, are quiescent, and are difficult to recruit into proliferation, implicating ELTC-IC as the most primitive human progenitor cells detectable in vitro. However, it

Numerical Modeling of short crack behavior in a thermal barrier coating upon thermal shock loading

The behavior of microstructurally short inherent cracks within a preoxidized thermal barrier coating system upon thermal shock loading is considered. A thin alumina oxide layer holding residual stresses was induced at the ceramic/metal interface to simulate thermally grown oxide on the bond coat. Undulation of the oxidized bond coat was modeled as a sinusoidal surface. The variations of the stress

Hyperfine-state-dependent lifetimes along the Ni-like isoelectronic sequence

An investigation of the lifetime of the 3d(9)4s D-3(3) level along a part of the nickel-like isoelectronic sequence has been performed. The focus of this work has been to evaluate the importance of the hyperfine induced electric quadrupole channel of the 3d(10) S-1(0)-3d(9)4s D-3(3) transition for isotopes with nuclear spin. Comparisons between the magnetic octupole transition rate and the hyperfi

Temperature dependence of the gain profile for THz quantum cascade lasers

We study the rapid decrease of peak gain in resonant-phonon THz Quantum Cascade Lasers with increasing temperature. The effect of various microscopic scattering processes on the gain profile as a function of temperature is discussed. We argue that increased broadening, prim arily due to increased impurity scattering, and not diminishing population inversion, is the main reason for the reduction of

Growth polarity and cell division in Streptomyces

Streptomycetes are mycelial bacteria that resemble filamentous fungi in their apical growth, branching, and morphogenetic development. One inroad into the largely unknown mechanisms underlying this prokaryotic growth polarity is provided by Streptomyces DivIVA, a protein localized at hyphal tips and involved in tip extension. Another aspect is a proposed migration of nucleoids. During sporulation,

Incorporation of substituted acrylamides to the lamellar mesophase of Aerosol OT

The structure and stability of the lamellar liquid crystal formed by the surfactant sodium bis-2ethylhexyl sulfosuccinate (AOT) in water is perturbed by small amounts of the substituted acrylamides N-isopropyl, N,N-diethyl, N-acryloylmorpholine, and N,N-dimethyl methacrylamide, as revealed by small angle X-ray scattering (SAXS), deuterium NMR, and microscopy. These molecules are water soluble and

Tissue engineering of cartilage: do we need it, can we do it, is it good and can we prove it? : do we need it, can we do it, is it good and can we prove it?

Current treatments of osteoarthritis (OA) focus on pain and loss of joint function. When these interventions fail, the destroyed joint is replaced by implants of metal, plastic and ceramics. In the future, we need to detect cartilage loss before it is too severe, prevent further loss and stimulate regrowth of lost cartilage. Research in tissue engineering can help us understand the complex require

Partial albinism in a semi-isolated population of great reed warblers

Albinism in birds is thought to result from the expression of recessive alleles that disrupt melanin pigmentation at feather development. We have studied great reed warblers Acrocephalus arundinaceus in a recently founded and increasing population in Sweden during 15 years for the presence of birds with albinistic feathers. The study population was founded in 1978 and the few cases of albinism was