High N, dry: Experimental nitrogen deposition exacerbates native shrub loss and nonnative plant invasion during extreme drought.

Hotter, longer, and more frequent global change-type drought events may profoundly impact terrestrial ecosystems by triggering widespread vegetation mortality. However, severe drought is only one component of global change, and ecological effects of drought may be compounded by other drivers, such as anthropogenic nitrogen (N) deposition and nonnative plant invasion. Elevated N deposition, for example, may reduce drought tolerance through increased plant productivity, thereby contributing to drought-induced mortality. High N availability also often favors invasive, nonnative plant species, and the loss of woody vegetation due to drought may create a window of opportunity for these invaders. We investigated the effects of multiple levels of simulated N deposition on a Mediterranean-type shrubland plant community in southern California from 2011 to 2016, a period coinciding with an extreme, multiyear drought in the region. We hypothesized that N addition would increase native shrub productivity, but that this would increase susceptibility to drought and result in increased shrub loss over time. We also predicted that N addition would favor nonnatives, especially annual grasses, leading to higher biomass and cover of these species. Consistent with these hypotheses, we found that high N availability increased native shrub canopy loss and mortality, likely due to the higher productivity and leaf area and reduced water-use efficiency we observed in shrubs subject to N addition. As native shrub cover declined, we also observed a concomitant increase in cover and biomass of nonnative annuals, particularly under high levels of experimental N deposition. Together, these results suggest that the impacts of extended drought on shrubland ecosystems may be more severe under elevated N deposition, potentially contributing to the widespread loss of native woody species and vegetation-type conversion

Thermal acoustic excitations with atomic-scale wavelengths in amorphous silicon

The vibrational properties of glasses remain a topic of intense interest due to several unresolved puzzles, including the origin of the Boson peak and the mechanisms of thermal transport. Inelastic scattering measurements have revealed that amorphous solids support collective acoustic excitations with low THz frequencies despite the atomic disorder, but these frequencies are well below most of the thermal vibrational spectrum. Here, we report the observation of acoustic excitations with frequencies up to 10 THz in amorphous silicon. The excitations have atomic-scale wavelengths as short as 6 Å and exist well into the thermal vibrational frequencies. Simulations indicate that these high-frequency waves are supported due to the high group velocity and monatomic composition of a-Si, suggesting that other glasses with these characteristics may also exhibit such excitations. Our findings demonstrate that a substantial portion of thermal vibrational modes in amorphous materials can still be described as a phonon gas despite the lack of atomic order

Thermal acoustic excitations with atomic-scale wavelengths in amorphous silicon

The vibrational properties of glasses remain a topic of intense interest due to several unresolved puzzles, including the origin of the Boson peak and the mechanisms of thermal transport. Inelastic scattering measurements have revealed that amorphous solids support collective acoustic excitations with low THz frequencies despite the atomic disorder, but these frequencies are well below most of the thermal vibrational spectrum. Here, we report the observation of acoustic excitations with frequencies up to 10 THz in amorphous silicon. The excitations have atomic-scale wavelengths as short as 6 Å and exist well into the thermal vibrational frequencies. Simulations indicate that these high-frequency waves are supported due to the high group velocity and monatomic composition of a-Si, suggesting that other glasses with these characteristics may also exhibit such excitations. Our findings demonstrate that a substantial portion of thermal vibrational modes in amorphous materials can still be described as a phonon gas despite the lack of atomic order

Thermoelectric properties of lead chalcogenide core-shell nanostructures

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials. On the basis of these results we propose suitable core-shell material combinations for future thermoelectric materials of large electric conductivities in combination with an increased thermopower by energy filtering.Comment: 12 pages, 8 figure

Comprehensive behavioral testing in the R6/2 mouse model of Huntington's disease shows no benefit from CoQ10 or minocycline

Previous studies of the effects of coenzyme Q10 and minocycline on mouse models of Huntington's disease have produced conflicting results regarding their efficacy in behavioral tests. Using our recently published best practices for husbandry and testing for mouse models of Huntington's disease, we report that neither coenzyme Q10 nor minocycline had significant beneficial effects on measures of motor function, general health (open field, rotarod, grip strength, rearing-climbing, body weight and survival) in the R6/2 mouse model. The higher doses of minocycline, on the contrary, reduced survival. We were thus unable to confirm the previously reported benefits for these two drugs, and we discuss potential reasons for these discrepancies, such as the effects of husbandry and nutrition

Pleural Dye Marking of Lung Nodules by Electromagnetic Navigation Bronchoscopy

IntroductionElectromagnetic navigation bronchoscopy (ENB)‐guided pleural dye marking is useful to localize small peripheral pulmonary nodules for sublobar resection.ObjectiveTo report findings on the use of ENB‐guided dye marking among participants in the NAVIGATE study.MethodsNAVIGATE is a prospective, multicentre, global and observational cohort study of ENB use in patients with lung lesions. The current subgroup report is a prespecified 1‐month interim analysis of ENB‐guided pleural dye marking in the NAVIGATE United States cohort.ResultsThe full United States cohort includes 1215 subjects from 29 sites (April 2015 to August 2016). Among those, 23 subjects (24 lesions) from seven sites underwent dye marking in preparation for surgical resection. ENB was conducted for dye marking alone in nine subjects while 14 underwent dye marking concurrent with lung lesion biopsy, lymph node biopsy and/or fiducial marker placement. The median nodule size was 10 mm (range 4‐22) and 83.3% were <20 mm in diameter. Most lesions (95.5%) were located in the peripheral third of the lung, at a median of 3.0 mm from the pleura. The median ENB‐specific procedure time was 11.5 minutes (range 4‐38). The median time from dye marking to resection was 0.5 hours (range 0.3‐24). Dye marking was adequate for surgical resection in 91.3%. Surgical biopsies were malignant in 75% (18/24).ConclusionIn this study, ENB‐guided dye marking to localize lung lesions for surgery was safe, accurate and versatile. More information is needed about surgical practice patterns and the utility of localization procedures.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151973/1/crj13077_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151973/2/crj13077.pd