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1.
It has previously been shown that the Copenhagen (COP) rat contains several genetic loci that contribute to its mammary tumor-resistant phenotype after 7,12-dimethylbenz(a)anthracene (DMBA) administration. One of these loci, mammary carcinoma susceptibility 1 (Mcs1), is located on the centromeric end of chromosome 2 and appears to act in a semidominant fashion. To confirm the existence and independent action of this locus and also aid in the identification of the physical location of the Mcs1 gene, congenic lines were generated by transferring the Mcs1 COP allele onto a Wistar Furth (WF) genetic background. Male carriers were genotyped using microsatellite markers spanning 20-30 cM of the Mcs1 locus. One of the congenic lines minimally retained the COP allele at D2Mit29 on the centromeric end of chromosome 2 and extended distally to D2Rat201. Heterozygous Mcs1 carrier rats were interbred, and the female offspring were treated with DMBA. The female rats from the Mcs1 congenic line that carried one or two COP alleles of the Mcs1 region had a significantly reduced (65 and 85%, respectively) tumor development (P < 0.001) compared with rats carrying zero COP alleles at this locus. A WF.COP-D2Mit29/D2Rat201 homozygous congenic strain derived at the N10 generation was treated with DMBA, and the COP homozygous rats developed 1.5 +/- 0.3 carcinomas/rat versus 6.3 +/- 0.5 in WF control rats (P < 0.0001). Fine mapping of this congenic interval using several recombinant lines identified three genetic loci within the Mcs1 congenic region that independently supported a tumor resistance phenotype. These genetic loci have been termed Mcs1a, Mcs1b, and Mcs1c. In rats for which each locus was homozygous for the COP allele, tumor development was reduced by approximately 60% compared with littermate controls. The identification of these independent loci within the Mcs1 COP allele provide a model of the genetic complexity of cancer.  相似文献   
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The formation of nanostructures with controlled size and morphology has been the focus of intensive research in recent years. Such nanostructures are important in the development of nanoscale devices and in the exploitation of the properties of nanomaterials. Here we show how tree-like nanostructures ('nanotrees') can be formed in a highly controlled way. The process involves the self-assembled growth of semiconductor nanowires via the vapour-liquid-solid growth mode. This bottom-up method uses initial seeding by catalytic nanoparticles to form the trunk, followed by the sequential seeding of branching structures. Each level of branching is controlled in terms of branch length, diameter and number, as well as chemical composition. We show, by high-resolution transmission electron microscopy, that the branching mechanism gives continuous crystalline (monolithic) structures throughout the extended and complex tree-like structures. The controlled seeding method that we report here has potential as a generic means of forming complex branching structures, and may also offer opportunities for applications, such as the mimicking of photosynthesis in nanotrees.  相似文献   
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In-air epitaxy of nanostructures (Aerotaxy) has recently emerged as a viable route for fast, large-scale production. In this study, we use small-angle X-ray scattering to perform direct in-flight characterizations of the first step of this process, i.e., the engineered formation of Au and Pt aerosol nanoparticles by spark generation in a flow of N2 gas. This represents a particular challenge for characterization because the particle density can be extremely low in controlled production. The particles produced are examined during production at operational pressures close to atmospheric conditions and exhibit a lognormal size distribution ranging from 5–100 nm. The Au and Pt particle production and detection are compared. We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding dominant physical properties, including the average particle diameter and sphericity, as influenced by particle sintering and the presence of aggregates. We observe highly sorted and sintered spherical Au nanoparticles at ultra-dilute concentrations (< 5 × 105 particles/cm3) corresponding to a volume fraction below 3 × 10–10, which is orders of magnitude below that of previously measured aerosols. We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis. Our study indicates that with high-intensity synchrotron beams and careful consideration of background removal, size and shape information can be obtained for extremely low particle concentrations with industrially relevant narrow size distributions.

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With river regulation, water withdrawal is common, reducing instream flows. The opposite alteration, flow augmentation, is less common and could reveal a mechanistic coordination between flow regime, channel form, and riparian ecosystems. The Little Bow River, a naturally intermittent prairie stream in Southern Alberta, has experienced flow augmentation since the late 1890s, and the Little Bow/Highwood Project of 2004 enabled a tripling of diversion flows from 2.9 to 8.5 m3/s. We investigated the subsequent responses by assessing the channel form and riparian vegetation based on aerial photographs taken in 2000 versus 2010, and riparian birds were assessed between 2005 and 2013 to investigate associations with riparian vegetation. Following recent flow augmentation, the mean channel width increased from 12.2 to 13.5 m, while sinuosity was relatively unchanged. Streamside zones with true willows (especially Salix exigua and Salix bebbiana) increased from 7 to 11% of the river corridor, and the facultative riparian wolf willow (Elaeagnus commutata) zones increased from 16 to 20%, while grassy zones decreased from 64 to 52%. Avian species richness and Shannon–Wiener index increased, while species evenness was relatively unaltered, suggesting an increase of rarer bird species in response to the increased habitat structure and diversity following the expansion of riparian shrubs and woodland. This study revealed responses to the recent flow augmentation over the first decade of implementation, and alterations following flow augmentation would likely continue for decades until the river and riparian zones adjust to the new flow regime. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
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A poor depiction of occupant behavior in building performance simulation frequently results in substantial divergences between real and simulated results. The problem may be of particular concern with simulation supporting the renovation of older multi-unit residential buildings, buildings whose occupants use windows for temperature control even during heating season. Here, we investigated the impact of window operation models (as well as other occupant behaviors) on simulated energy performance in university residence halls. Based on environmental monitoring, along with information collected from occupant surveys and wearable devices, we estimated air exchange rates and developed a probabilistic window-operation prediction model. The data were collected in 76 dormitory rooms sampled from a pre-renovated historic building and two similar buildings. We then evaluated the window-operation model’s predictive performance in 15 dormitory rooms in the post-renovated building with new occupants. The results of our predictive model were also compared with previously reported window-operation models. We implemented each window-operation model in a calibrated EnergyPlus building performance model, comparing the results of each simulation to metered hourly steam consumption. The impact of the different window operation models on simulated heating energy use was significant (annual error ranging from 0.2% to 10%). Our model demonstrated the highest capability of predicting window state (accuracy=85.8%) and steam use (NMBE=?0.2%); however, some previously published windowoperation models also produced satisfactory performance, implying that such models may be generalizable to some extent. The results suggest that data collected from somewhat ubiquitous indoor environmental quality sensors can glean insights into occupant behavior for building performance simulation. Furthermore, the energy impacts resulting from the variations in occupant behavior studied here were large enough to show that the choice of behavior model can have meaningful implications for real-world applications, such as estimating saving from heating and lighting system upgrades.  相似文献   
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