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Search Results: 1 - 10 of 512 matches for " Thor Veen "
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Premating Reproductive Barriers between Hybridising Cricket Species Differing in Their Degree of Polyandry
Thor Veen,Joseph Faulks,Rolando Rodríguez-Mu?oz,Tom Tregenza
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019531
Abstract: Understanding speciation hinges on understanding how reproductive barriers arise between incompletely isolated populations. Despite their crucial role in speciation, prezygotic barriers are relatively poorly understood and hard to predict. We use two closely related cricket species, Gryllus bimaculatus and G. campestris, to experimentally investigate premating barriers during three sequential mate choice steps. Furthermore, we experimentally show a significant difference in polyandry levels between the two species and subsequently test the hypothesis that females of the more polyandrous species, G. bimaculatus, will be less discriminating against heterospecific males and hence hybridise more readily. During close-range mating behaviour experiments, males showed relatively weak species discrimination but females discriminated very strongly. In line with our predictions, this discrimination is asymmetric, with the more polyandrous G. bimaculatus mating heterospecifically and G. campestris females never mating heterospecifically. Our study shows clear differences in the strength of reproductive isolation during the mate choice process depending on sex and species, which may have important consequences for the evolution of reproductive barriers.
Identifying the African Wintering Grounds of Hybrid Flycatchers Using a Multi–Isotope (δ2H, δ13C, δ15N) Assignment Approach
Thor Veen, M?rten B. Hjernquist, Steven L. Van Wilgenburg, Keith A. Hobson, Eelke Folmer, Laura Font, Marcel Klaassen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098075
Abstract: Migratory routes and wintering grounds can have important fitness consequences, which can lead to divergent selection on populations or taxa differing in their migratory itinerary. Collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers breeding in Europe and wintering in different sub-Saharan regions have distinct migratory routes on the eastern and western sides of the Sahara desert, respectively. In an earlier paper, we showed that hybrids of the two species did not incur reduced winter survival, which would be expected if their migration strategy had been a mix of the parent species' strategies potentially resulting in an intermediate route crossing the Sahara desert to different wintering grounds. Previously, we compared isotope ratios and found no significant difference in stable-nitrogen isotope ratios (δ15N) in winter-grown feathers between the parental species and hybrids, but stable-carbon isotope ratios (δ13C) in hybrids significantly clustered only with those of pied flycatchers. We followed up on these findings and additionally analyzed the same feathers for stable-hydrogen isotope ratios (δ2H) and conducted spatially explicit multi-isotope assignment analyses. The assignment results overlapped with presumed wintering ranges of the two species, highlighting the efficacy of the method. In contrast to earlier findings, hybrids clustered with both parental species, though most strongly with pied flycatcher.
Detecting Periodic Elements in Higher Topological Hochschild Homology
Torleif Veen
Mathematics , 2013,
Abstract: Given a commutative ring spectrum $R$ let $\Lambda_XR$ be the Loday functor constructed by Brun, Carlson and Dundas, which is equivalent to the tensor $X\otimes R$ in the category of commutative ring spectra. Given a prime $p\geq 5$ we calculate $\pi_*(\Lambda_{T^n}H\mathbb{F}_p)$ for $n\leq p$, and find a formula for the operator $\sigma:\pi_*(\Lambda_{T^{n}}H\mathbb{F}_p)\rightarrow \pi_*(\Lambda_{T^{n+1}}H\mathbb{F}_p)$ induced by the standard natural map $S^1_+\wedge \Lambda_{T^{n}}H\mathbb{F}_p\rightarrow \Lambda_{T^{n+1}}H\mathbb{F}_p$. Let $\mu_i$ be the image in $\pi_*(\Lambda_{T^{n}}H\mathbb{F}_p)$ of a generator of $\pi_2(\Lambda_{S^1}H\mathbb{F}_p)$ under the inclusion of the $i$-th circle. Using the two result above we will deduce that the Rognes element $t_1\mu_1^{p^{n-1}}+\ldots+t_n\mu_n^{p^{n-1}}$ in the homotopy fixed points spectral sequence calculating $\pi_*((\Lambda_{T^{n}}H\mathbb{F}_p)^{hT^{n}})$, is not hit by any differential and thus represent an element called the Rognes class. Using this we prove that $v_{n-1}$ in the $n-1$-th connective Morava $K$-theory of $(\Lambda_{T^{n}}H\mathbb{F}_p)^{hT^{n}}$ is detected by the Rognes class.
Mandated data archiving greatly improves access to research data
Timothy H. Vines,Rose L. Andrew,Dan G. Bock,Michelle T. Franklin,Kimberly J. Gilbert,Nolan C. Kane,Jean-Sébastien Moore,Brook T. Moyers,Sébastien Renaut,Diana J. Rennison,Thor Veen,Sam Yeaman
Computer Science , 2013, DOI: 10.1096/fj.12-218164
Abstract: The data underlying scientific papers should be accessible to researchers both now and in the future, but how best can we ensure that these data are available? Here we examine the effectiveness of four approaches to data archiving: no stated archiving policy, recommending (but not requiring) archiving, and two versions of mandating data deposition at acceptance. We control for differences between data types by trying to obtain data from papers that use a single, widespread population genetic analysis, STRUCTURE. At one extreme, we found that mandated data archiving policies that require the inclusion of a data availability statement in the manuscript improve the odds of finding the data online almost a thousand-fold compared to having no policy. However, archiving rates at journals with less stringent policies were only very slightly higher than those with no policy at all. At one extreme, we found that mandated data archiving policies that require the inclusion of a data availability statement in the manuscript improve the odds of finding the data online almost a thousand fold compared to having no policy. However, archiving rates at journals with less stringent policies were only very slightly higher than those with no policy at all. We also assessed the effectiveness of asking for data directly from authors and obtained over half of the requested datasets, albeit with about 8 days delay and some disagreement with authors. Given the long term benefits of data accessibility to the academic community, we believe that journal based mandatory data archiving policies and mandatory data availability statements should be more widely adopted.
On the special current and water level variations in the channel of S?o Sebasti?o
Kvinge, Thor;
Boletim do Instituto Oceanográfico , 1967, DOI: 10.1590/S0373-55241967000100003
Abstract: in this paper were discussed current measurements recorded at 5 meter depth in the s?o sebasti?o channel and its correlation with tidal currents and prevailing weather conditions. it has been shown that the recorded current is dominated by long periodic variation with periods of about four days and is characterized by a net transport towards ne. computations of the currents of tidal origin have shown that they are very small and of minor importance to the current conditions in the channel, however there are evidences of the connection between the non tidal currents, the irregular sea level variation and the prevailing weather conditions.
Porous Titanium Granules and Blood for Bone Regeneration around Dental Implants: Report of Four Cases and Review of the Literature
Andreas Thor
Case Reports in Dentistry , 2013, DOI: 10.1155/2013/410515
Abstract:
Implicit-explicit methods based on strong stability preserving multistep time discretizations
Thor Gjesdal
Mathematics , 2003,
Abstract: In this note we propose and analyze novel implicit-explicit methods based on second order strong stability preserving multistep time discretizations. Several schemes are developed, and a linear stability analysis is performed to study their properties with respect to the implicit and explicit eigenvalues. One of the proposed schemesis found to have very good stability properties, with implicit A-stability for the entire explicit stability domain. The properties of the other proposed schemes are comparable to those of traditional methods found in the literature.
Neonatal transports—risks and opportunities  [PDF]
Alf Meberg, Thor Willy Ruud Hansen
Open Journal of Pediatrics (OJPed) , 2011, DOI: 10.4236/ojped.2011.14013
Abstract: Aim: To assess the need for and quality of neonatal transports. Material and methods: Prospective observational study of consecutive transports from a level II neonatal unit. Results: 500 transports were undertaken 1982-2010 in 445 patients, representing 0.7% of liveborn infants (n = 61 450). Indications were congenital malformations in 223 (45%), prematurity/respiratory distress syndrome (RDS) in 87 (17%), and other conditions in 190 (38%). For patients ventilated during transport (n = 121) mean pCO2 was improved at arrival, and for spontaneously breathing patients mean pH, pCO2, and base excess (p < 0.05). After establishing a local respirator programme from 1989, transports for prematurity/RDS declined from 3.4 per 1000 live born infants in 1982-88 to 0.8 per 1 000 in 1989-2010 (p < 0.0001), and night-time transports (departure between 22.00 pm - 06.00 am) declined from 24/119 (20%) to 38/381 (10%) (p = 0.003). Technical mishaps or severe clinical deterioration occurred in 16 (3%) of the transports. Conclusions: Neonatal transport carries risks, but also an opportunity for further stabilization and improvement. A local respirator programme reduced the need for transfer of premature infants with RDS as well as for transports during night-time.
Angiosarcoma of the mandible: Metastasis from a primary tumor of the right atrium of the heart  [PDF]
Anwar Ramadhan, Helena Willén, Andreas Thor
Case Reports in Clinical Medicine (CRCM) , 2013, DOI: 10.4236/crcm.2013.21015
Abstract:

Angiosarcoma of the heart is a rare tumor with very poor prognosis especially in a patient with multiple metastases. We present a case of a 39-year-old woman with angiosarcoma of the heart metastasing to the right side of the mandible, a situation not often found previously in the literature.

Ossoran Tempon Daomai Langi’
H. van der Veen
Bijdragen tot de Taal-, Land- en Volkenkunde , 1976,
Abstract:
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