366 research outputs found
Experimental material handling device Final report
Design, fabrication and test of materials handling device for spacecraft us
Structural and Magnetic Characterization of Large Area, Free-Standing Thin Films of Magnetic Ion Intercalated Dichalcogenides Mn0.25TaS2 and Fe0.25TaS2
Free-standing thin films of magnetic ion intercalated transition metal
dichalcogenides are produced using ultramicrotoming techniques. Films of
thicknesses ranging from 30nm to 250nm were achieved and characterized using
transmission electron diffraction and X-ray magnetic circular dichroism.
Diffraction measurements visualize the long range crystallographic ordering of
the intercalated ions, while the dichroism measurements directly assess the
orbital contributions to the total magnetic moment. We thus verify the
unquenched orbital moment in Fe0.25TaS2 and measure the fully quenched orbital
contribution in Mn0.25TaS2. Such films can be used in a wide variety of
ultrafast X-ray and electron techniques that benefit from transmission
geometries, and allow measurements of ultrafast structural, electronic, and
magnetization dynamics in space and time
Lafutidine, a Protective H2 Receptor Antagonist, Enhances Mucosal Defense in Rat Esophagus
Luminal acid or CO2 induces a hyperemic response in the esophagus, via activation of acid sensors on capsaicin-sensitive afferent nerves (CSAN). Since disruption of the hyperemic response to luminal CO2 acidifies the interstitium of the esophageal mucosa, the hyperemic response may maintain interstitial pH (pHint). We hypothesized that acid-related hyperemia maintains pHint, preventing acid-induced injury in the esophageal mucosa.
We examined the effects of capsaicin (Cap) or lafutidine (Laf), a mucosal protective H2 antagonist, on the regulation of pHint and blood flow in rat esophagus using ratiometric microimaging and laser-Doppler measurements of the lower esophageal mucosa of living rats. The esophagus was topically superfused with pH 7.0 buffer, or a pH 1.0 or pH 1.0 + pepsin (1 mg/ml) solution with or without Laf.
Cap (30 or 100 µM) or Laf (0.1 or 1 mM) dose-dependently increased blood flow, accompanied by increased pHint. The pH 1.0 solution increased blood flow without pHint change, whereas Laf (1 mM) increased blood flow and pHint during acid exposure. The effects of Laf were abolished by ablation of CSAN. Perfusion of the acidified pepsin solution gradually decreased pHint, inhibited by Laf perfusion.
Activation of CSAN by Laf with or without acid, accompanied by hyperemia, increased pHint, preventing acidified pepsin-induced interstitial acidification. Stimulation of the capsaicin pathway with compounds such as Laf enhances mucosal protection from acid-related injury in the upper gastrointestinal tract
Probing photo-induced melting of antiferromagnetic order in La0.5Sr1.5MnO4 by ultrafast resonant soft X-ray diffraction
Photo-excitation in complex oxides1 transfers charge across semicovalent
bonds, drastically perturbing spin and orbital orders2. Light may then be used
in compounds like magnetoresistive manganites to control magnetism on nanometre
lengthscales and ultrafast timescales. Here, we show how ultrafast resonant
soft x-ray diffraction can separately probe the photo-induced dynamics of spin
and orbital orders in La0.5Sr1.5MnO4. Ultrafast melting of CE antiferromagnetic
spin order is evidenced by the disappearance of a (1/4,1/4,1/2) diffraction
peak. On the other hand the (1/4,1/4,0) peak, reflecting orbital order, is only
partially reduced. Cluster calculations aid our interpretation by considering
different magnetically ordered states accessible after photo-excitation.
Nonthermal coupling between light and magnetism emerges as a primary aspect of
photo-induced phase transitions in manganites.Comment: 7 pages manuscript, 4 figure
Deconstructing the Hubbard Hamiltonian by Ultrafast Quantum Modulation Spectroscopy in Solid-state Mott Insulators
Optical pulses at THz and mid-infrared frequencies tuned to specific vibrational resonances modulate the lattice along chosen normal mode coordinates. In this way, solids can be switched between competing electronic phases and new states are created. Here, we use vibrational modulation to make electronic interactions (Hubbard-U) in Mott-insulator time dependent. Mid-infrared optical pulses excite localized molecular vibrations in ET-F<sub>2</sub>TCNQ, a prototypical one-dimensional Mott-insulator. A broadband ultrafast probe interrogates the resulting optical spectrum between THz and visible frequencies. A red-shifted charge-transfer resonance is observed, consistent with a time-averaged reduction of the electronic correlation strength U. Secondly, a sideband manifold inside of the Mott-gap appears, resulting from a periodically modulated U. The response is compared to computations based on a quantum-modulated dynamic Hubbard model. Heuristic fitting suggests asymmetric holon-doublon coupling to the molecules and that electron double-occupancies strongly squeeze the vibrational mode
Developing Secure Power Systems Professional Competence: Alignment and Gaps in Workforce Development Programs?Summary Report
This document is a summarization of the report, Developing Secure Power Systems Professional Competence: Alignment and Gaps in Workforce Development Programs, the final report for phase 2 of the SPSP (DOE workforce study) project
Evolution of three-dimensional correlations during the photoinduced melting of antiferromagnetic order in La
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Late phonological development in Spanish children with bilateral hearing loss / Desarrollo fonologico tardio en ninos espanoles con perdidas auditivas bilaterales
This study has a twofold objective: to analyse and compare the phonological processes in a sample of Spanish children with hearing loss, both with a cochlear implant and with a hearing aid, with a group with normal hearing; and to determine whether there are differences between the participants with a cochlear implant and with a hearing aid in the frequency and nature of the phonological processes. The sample is made up of 168 participants, eight with hearing loss (four with an implant and four with a hearing aid) and 160 with normal hearing. Samples of spontaneous speech were collected and transcribed using the tools from the CHILDES project. For the analysis, the phonological processes paradigm was adopted, evaluating phonological development based on normative error rates. The participants with a hearing loss show slower phonological development in terms of phonological processes, along with atypical processes. Furthermore, the participants with cochlear implants committed more phonological errors than those that wear a hearing aid. The implications of the results are discussed, and it is recommended that auditory stimulation should be done early in children with hearing loss regardless of their technical aid
A Vulnerability Assessment of Fish and Invertebrates to Climate Change on the Northeast U.S. Continental Shelf
Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability
Fluorescence activated cell sorting followed by small RNA sequencing reveals stable microRNA expression during cell cycle progression.
BACKGROUND: Previously, drug-based synchronization procedures were used for characterizing the cell cycle dependent transcriptional program. However, these synchronization methods result in growth imbalance and alteration of the cell cycle machinery. DNA content-based fluorescence activated cell sorting (FACS) is able to sort the different cell cycle phases without perturbing the cell cycle. MiRNAs are key transcriptional regulators of the cell cycle, however, their expression dynamics during cell cycle has not been explored. METHODS: Following an optimized FACS, a complex initiative of high throughput platforms (microarray, Taqman Low Density Array, small RNA sequencing) were performed to study gene and miRNA expression profiles of cell cycle sorted human cells originating from different tissues. Validation of high throughput data was performed using quantitative real time PCR. Protein expression was detected by Western blot. Complex statistics and pathway analysis were also applied. RESULTS: Beyond confirming the previously described cell cycle transcriptional program, cell cycle dependently expressed genes showed a higher expression independently from the cell cycle phase and a lower amplitude of dynamic changes in cancer cells as compared to untransformed fibroblasts. Contrary to mRNA changes, miRNA expression was stable throughout the cell cycle. CONCLUSIONS: Cell cycle sorting is a synchronization-free method for the proper analysis of cell cycle dynamics. Altered dynamic expression of universal cell cycle genes in cancer cells reflects the transformed cell cycle machinery. Stable miRNA expression during cell cycle progression may suggest that dynamical miRNA-dependent regulation may be of less importance in short term regulations during the cell cycle
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