2,524 research outputs found

    Polydactylous limbs in Strong's Luxoid mice result from ectopic polarizing activity

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    Strong's Luxoid (1st^D) is a semidominant mouse mutation in which heterozygotes show preaxial hindlimb polydactyly, and homozygotes show fore- and hindlimb polydactyly. The digit patterns of these polydactylous limbs resemble those caused by polarizing grafts, since additional digits with posterior character are present at the anterior side of the limb. Such observations suggest that 1st^D limb buds might contain a genetically determined ectopic region of polarizing activity. Accordingly, we show that mutant embryos ectopically express the pattern-determining genes fibroblast growth factor 4 (fgf-4), sonic hedgehog (shh), and Hoxd-12 in the anterior region of the limb. Further, we show that anterior mesoderm from mutant limbs exhibits polarizing activity when grafted into host chicken limbs. In contrast to an experimentally derived polydactylous transgenic mouse, forelimbs of homozygotes show a normal pattern of Hoxb-8 expression, indicating that the duplication of polarizing tissue here occurs downstream or independently of Hoxb-8. We suggest that the 1st gene product is involved in anteroposterior axis formation during normal limb development

    Vibrational Exciton Density of States in Solid Benzene

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    Computer‐aided calculations, based on experimentally‐fitted pairwise interaction terms, give the complete exciton density‐of‐states profile for the entire Brillouin zone. The restricted Frenkel model, with short‐range interactions, is the key assumption. Results are given and discussed for the out‐of‐plane a2ua2u normal mode Îœ11Îœ11(C6H6 and C6D6), for Îœ12(b1u)Îœ12(b1u), and for Îœ15(b2u)Îœ15(b2u). The wide range of parameters used makes this investigation pertinent to other vibrational and electronic exciton bands of benzene and any other molecular crystal with the same interchange symmetry. Also, Van Hove singularities are found to be more important for symmetry‐based critical points than for “accidental” critical points. Present‐day experimental and theoretical intermolecular excitation exchange interaction terms are compared.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71006/2/JCPSA6-53-9-3674-1.pd

    Lexical threshold revisited: Lexical text coverage, learners’ vocabulary size and reading comprehension

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    We explore the relationship between second language (L2) learners’ vocabulary size, lexical text coverage that their vocabulary provides and their reading comprehension. We also conceptualize “adequate reading comprehension” and look for the lexical threshold for such reading in terms of coverage and vocabulary size. Vocabulary size was measured by the Levels Test, lexical coverage by the newest version of Vocabulary Profile and reading comprehension by a standardized national test. Results show that small increments of vocabulary knowledge contribute to reading comprehension even though they hardly improve text coverage. We suggest two thresholds: an optimal one, which is the knowledge of 8,000 word families yielding the coverage of 98% (including proper nouns) and a minimal one, which is 4,000–5,000 word families resulting in the coverage of 95% (including proper nouns)

    Evaluation of a Technology-Based Survivor Care Plan for Breast Cancer Survivors: Pre-Post Pilot Study.

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    BACKGROUND: As of 2016, almost 16 million individuals were cancer survivors, including over 3.5 million survivors of breast cancer. Because cancer survivors are living longer and have unique health care needs, the Institute of Medicine proposed a survivor care plan as a way to alleviate the many medical, emotional, and care coordination problems of survivors. OBJECTIVE: This pilot study for breast cancer survivors was undertaken to: (1) examine self-reported changes in knowledge, confidence, and activation from before receipt to after receipt of a survivor care plan; and (2) describe survivor preferences for, and satisfaction with, a technology-based survivor care plan. METHODS: A single group pretest-posttest design was used to study breast cancer survivors in an academic cancer center and a community cancer center during their medical visit after they completed chemotherapy. The intervention was a technology-based survivor care plan. Measures were taken before, immediately after, and 1 month after receipt of the survivor care plan. RESULTS: A total of 38 breast cancer survivors agreed to participate in the study. Compared to baseline levels before receipt of the survivor care plan, participants reported increased knowledge both immediately after its receipt at the academic center (P\u3c.001) and the community center (P\u3c.001) as well as one month later at the academic center (P=.002) and the community center (P\u3c.001). Participants also reported increased confidence immediately following receipt of the survivor care plan at the academic center (P=.63) and the community center (P=.003) and one month later at both the academic center (P=.63) and the community center (P\u3c.001). Activation was increased from baseline to post-survivor care plan at both the academic center (P=.05) and community center (P\u3c.001) as well as from baseline to 1-month follow-up at the academic center (P=.56) and the community center (P\u3c.001). Overall, community center participants had lower knowledge, confidence, and activation at baseline compared with academic center participants. Overall, 22/38 (58%) participants chose the fully functional electronic survivor care plan. However, 12/23 (52%) in the community center group chose the paper version compared to 4/15 (27%) in the academic center group. Satisfaction with the format (38/38 participants) and the content (37/38 participants) of the survivor care plan was high for both groups. CONCLUSIONS: This study provides evidence that knowledge, confidence, and activation of survivors were associated with implementation of the survivor care plan. This research agrees with previous research showing that cancer survivors found the technology-based survivor care plan to be acceptable. More research is needed to determine the optimal approach to survivor care planning to ensure that all cancer survivors can benefit from it

    HiPEP Ion Optics System Evaluation Using Gridlets

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    Experimental measurements are presented for sub-scale ion optics systems comprised of 7 and 19 aperture pairs with geometrical features that are similar to the HiPEP ion optics system. Effects of hole diameter and grid-to-grid spacing are presented as functions of applied voltage and beamlet current. Recommendations are made for the beamlet current range where the ion optics system can be safely operated without experiencing direct impingement of high energy ions on the accelerator grid surface. Measurements are also presented of the accelerator grid voltage where beam plasma electrons backstream through the ion optics system. Results of numerical simulations obtained with the ffx code are compared to both the impingement limit and backstreaming measurements. An emphasis is placed on identifying differences between measurements and simulation predictions to highlight areas where more research is needed. Relatively large effects are observed in simulations when the discharge chamber plasma properties and ion optics geometry are varied. Parameters investigated using simulations include the applied voltages, grid spacing, hole-to-hole spacing, doubles-to-singles ratio, plasma potential, and electron temperature; and estimates are provided for the sensitivity of impingement limits on these parameters

    Inferential NMR/X-ray-based structure determination of a dibenzo[a,d]cycloheptenone inhibitor-p38a MAP kinase complex in solution.

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    Complex problem: The crystal structure of p38α mitogen-activated protein kinase in complex with a dibenzo[a,d]cycloheptenone inhibitor was found to be incompatible with NMR data of the same complex in solution. By using inferential structure determination (ISD) with restraints from X-ray crystallography and NMR spectra, a structure that is compatible with both data sets and very close to the X-ray crystal structure was generated (see picture)

    Endocrine-disrupting alkylphenols are widespread in the blood of lobsters from southern New England and adjacent offshore areas

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    Author Posting. © National Shellfisheries Association , 2012. This article is posted here by permission of National Shellfisheries Association for personal use, not for redistribution. The definitive version was published in Journal of Shellfish Research 31 (2012): 563-571, doi:10.2983/035.031.0216.Endocrine-disrupting pollutants in rivers and oceans represent a poorly understood but potentially serious threat to the integrity of aquatic and coastal ecosystems. We surveyed the hemolymph of lobsters from across southern New England and adjacent offshore areas for 3 endocrine-disrupting alkylphenols. We found all 3 compounds in hemolymph from every year and almost every region sampled. Prevalence of contamination varied significantly between regions, ranging from 45% of lobsters from southern Massachusetts to 17% of lobsters from central Long Island Sound. Mean contamination levels varied significantly as a function of region, year sampled, and collection trip, and were highest overall in lobsters from western Long Island Sound and lowest in lobsters from central Long Island Sound. Surprisingly, lobsters from offshore areas were not less contaminated than lobsters from inshore areas. Contamination levels also did not vary as a function of lobster size or shell disease signs. Contaminated lobsters held in the laboratory did not retain alkylphenols, suggesting that hemolymph contamination levels represent recent, rather than long-term, exposure. Our data set is the first, to our knowledge, to survey endocrine-disrupting contaminants in a population across such a broad temporal and spatial scale. We show that alkylphenol contamination is a persistent, widespread, but environmentally heterogeneous problem in lobster populations in southern New England and adjacent offshore areas. Our work raises serious questions about the prevalence and accumulation of these endocrine-disrupting pollutants in an important fishery species.This work was supported by the National Marine Fisheries Service as the New England Lobster Research Initiative: Lobster Shell Disease under NOAA grant NA06NMF4720100 to the University of Rhode Island Fisheries Center

    Development of tuneable Fabry-Perot sensors for parallelised photoacoustic signal acquisition

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    Fabry-PĂ©rot (FP) sensors have enabled high resolution 3D photoacoustic (PA) imaging in backward mode. However, raster-scanning of the interrogation laser beam across the sensor can result in slow 3D image acquisition. To overcome this limitation, parallelized PA signal acquisition can be used for which FP sensors with uniform optical thickness are required. In this work, the optical thickness is tuned a) irreversibly through the use of a photopolymer host matrix and b) actively using embedded electro-optic (EO) chromophores. Polymer spacers (5 ÎŒm) were deposited using spin coating and sandwiched between two dielectric mirrors and transparent ITO electrodes. The employed polymer guest-host system consists of an EO chromophore (2-methyl-4-nitroaniline) and poly(vinyl cinnamate). EO tuneability was induced using contact poling and a tuneability of 68 pm was demonstrated. The optical thickness was homogenised by raster scanning a UV beam whilst varying the exposure time across a 4 mm2 detection aperture

    Development of a backward-mode photoacoustic microscope using a Fabry-Perot sensor

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    Optical-resolution photoacoustic microscopy (PAM) has been shown to enable the acquisition of high resolution (ÎŒm) functional and anatomical images. For backward-mode operation, conventional piezoelectric ultrasound transducers need to be placed far away from the signal source due to their opacity and size. This can result in reduced acoustic sensitivity. Planar Fabry-Perot polymer film interferometer (FPI) sensors have the potential to overcome this limitation since they are transparent to the excitation wavelength, can be placed immediately adjacent to the signal source for high acoustic sensitivity, and offer a broadband frequency response (0 –50 MHz). In this study, we present a high frame rate, backward-mode OR-PAM system based on a planar FPI ultrasound sensor. A ns-pulsed laser provides excitation pulses (<200 nJ, maximum pulse repetition frequency = 200 kHz, 532 nm) to generate photoacoustic waves that are detected using a planar FPI sensor interrogated at 765-781 nm. For backwardmode operation and highest acoustic sensitivity, the excitation and interrogation beams are coaxially aligned and rasterscanned. The optical transfer function of the sensor, the spatial resolution and the detection sensitivity were determined to characterise the set-up. Images of a leaf phantom and first in vivo images of zebrafish larvae were acquired. This approach will enable fast 3D OR-PAM with high resolution and high sensitivity for functional and molecular imaging applications. FPI-based ultrasound detection also has the potential to enable dual-mode optical- and acousticresolution PAM and the integration of photoacoustic imaging with purely optical modalities such as multi-photon microscopy

    A Cluster-Matching-Based Method for Video Face Recognition

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    Face recognition systems are present in many modern solutions and thousands of applications in our daily lives. However, current solutions are not easily scalable, especially when it comes to the addition of new targeted people. We propose a cluster-matching-based approach for face recognition in video. In our approach, we use unsupervised learning to cluster the faces present in both the dataset and targeted videos selected for face recognition. Moreover, we design a cluster matching heuristic to associate clusters in both sets that is also capable of identifying when a face belongs to a non-registered person. Our method has achieved a recall of 99.435% and a precision of 99.131% in the task of video face recognition. Besides performing face recognition, it can also be used to determine the video segments where each person is present.Comment: 13 page
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