865 research outputs found
Transfer of training between distinct motor tasks after stroke: Implications for task-specific approaches to upper-extremity neurorehabilitation
BACKGROUND: Although task-specific training is emerging as a viable approach for recovering motor function after stroke, there is little evidence for whether the effects of such training transfer to other functional motor tasks not directly practiced in therapy. OBJECTIVE: The purpose of the current study was to test whether training on one motor task would transfer to untrained tasks that were either spatiotemporally similar or different in individuals with chronic hemiparesis post-stroke. METHODS: Eleven participants with chronic mild-to-moderate hemiparesis following stroke completed five days of supervised massed practice of a feeding task with their affected side. Performance on the feeding task, along with two other untrained functional upper extremity motor tasks (sorting, dressing) was assessed before and after training. RESULTS: Performance of all three tasks improved significantly after training exclusively on one motor task. The amount of improvement in the untrained tasks was comparable, and was not dependent on the degree of similarity to the trained task. CONCLUSIONS: Because the number and type of tasks that can be practiced are often limited within standard stroke rehabilitation, results from this study will be useful for designing task-specific training plans to maximize therapy benefits
Rotation periods of late-type stars in the young open cluster IC 2602
We present the results of a monitoring campaign aimed at deriving rotation
periods for a representative sample of stars in the young (30 Myr) open cluster
IC 2602. Rotation periods were derived for 29 of 33 stars monitored. The
periods derived range from 0.2d (one of the shortest known rotation periods of
any single open cluster star) to about 10d (which is almost twice as long as
the longest period previously known for a cluster of this age). We are able to
confirm 8 previously known periods and derive 21 new ones, delineating the long
period end of the distribution. Despite our sensitivity to longer periods, we
do not detect any variables with periods longer than about 10d. The combination
of these data with those for IC 2391, an almost identical cluster, leads to the
following conclusions:
1) The fast rotators in a 30 Myr cluster are distributed across the entire
0.5 < B-V < 1.6 color range.
2) 6 stars in our sample are slow rotators, with periods longer than 6d.
3) The amplitude of variability depends on both the color and the period. The
dependence on the latter might be important in understanding the selection
effects in the currently available rotation period database and in planning
future observations.
4) The interpretation of these data in terms of theoretical models of
rotating stars suggests both that disk-interaction is the norm rather than the
exception in young stars and that disk-locking times range from zero to a few
Myr.Comment: 23 pages, 8 figures, accepted for publication in the Astrophysical
Journa
VLT Spectroscopy of Ultra-Faint Dwarf Galaxies. 1. Bo\"otes I, Leo IV, Leo V
We perform consistent reductions and measurements for three ultra-faint dwarf
galaxies (UFDs): Bo\"otes I, Leo IV and Leo V. Using the public archival data
from the GIRAFFE spectrograph on the Very Large Telescope (VLT), we locate new
members and provide refined measurements of physical parameters for these dwarf
galaxies. We identify nine new Leo IV members and four new Leo V members, and
perform a comparative analysis of previously discovered members. Additionally,
we identify one new binary star in both Leo IV and Leo V. After removing binary
stars, we recalculate the velocity dispersions of Bo\"otes I and Leo IV to be
5.1 and 3.4 km s, respectively; We do
not resolve the Leo V velocity dispersion. We identify a weak velocity gradient
in Leo V that is 4 smaller than the previously calculated
gradient and that has a corresponding position angle which differs from the
literature value by 120 deg. Combining the VLT data with previous
literature, we re-analyze the Bo\"otes I metallicity distribution function and
find that a model including infall of pristine gas while Bo\"otes I was forming
stars best fits the data. Our analysis of Leo IV, Leo V and other UFDs will
enhance our understanding of these enigmatic stellar populations and contribute
to future dark matter studies. This is the first in a series of papers
examining thirteen UDFs observed with VLT/GIRAFFE between 2009 and 2017.
Similar analyses of the remaining ten UFDs will be presented in forthcoming
papers.Comment: 29 pages, 18 figures, 8 tables. Accepted for publication on ApJ. Code
and data can be found at https://github.com/sazabi4/vlt_dwarf
Time-domain Implementation of the Optimal Cross-Correlation Statistic for Stochastic Gravitational-Wave Background Searches in Pulsar Timing Data
Supermassive black hole binaries, cosmic strings, relic gravitational waves
from inflation, and first order phase transitions in the early universe are
expected to contribute to a stochastic background of gravitational waves in the
10^(-9) Hz-10^(-7) Hz frequency band. Pulsar timing arrays (PTAs) exploit the
high precision timing of radio pulsars to detect signals at such frequencies.
Here we present a time-domain implementation of the optimal cross-correlation
statistic for stochastic background searches in PTA data. Due to the irregular
sampling typical of PTA data as well as the use of a timing model to predict
the times-of-arrival of radio pulses, time-domain methods are better suited for
gravitational wave data analysis of such data. We present a derivation of the
optimal cross-correlation statistic starting from the likelihood function, a
method to produce simulated stochastic background signals, and a rigorous
derivation of the scaling laws for the signal-to-noise ratio of the
cross-correlation statistic in the two relevant PTA regimes: the weak signal
limit where instrumental noise dominates over the gravitational wave signal at
all frequencies, and a second regime where the gravitational wave signal
dominates at the lowest frequencies.Comment: 12 pages, 3 figures, submitted to Physical Review
In children, the microbiota of the nasopharynx and bronchoalveolar lavage fluid are both similar and different
RATIONALE:
Sputum and bronchoalveolar lavage fluid (BALF) are often obtained to elucidate the lower airway microbiota in adults. Acquiring sputum samples from children is difficult and obtaining samples via bronchoscopy in children proves challenging due to the need for anesthesia and specialized procedural expertise; therefore nasopharyngeal (NP) swabs are often used as surrogates when investigating the pediatric airway microbiota. In adults, the airway microbiota differs significantly between NP and BALF samples however, minimal data exist in children.
OBJECTIVES:
To compare NP and BALF samples in children undergoing clinically indicated bronchoscopy.
METHODS:
NP and BALF samples were collected during clinically indicated bronchoscopy. Bacterial DNA was extracted from 72 samples (36 NP/BALF pairs); the bacterial V1-V3 region of the 16S rRNA gene was amplified and sequenced on the Illumina Miseq platform. Analysis was performed using mothur software.
RESULTS:
Compared to NP samples, BALF had increased richness and diversity. Similarity between paired NP and BALF (intra-subject) samples was greater than inter-subject samples (P = 0.0006). NP samples contained more Actinobacteria (2.2% vs 21%; adjusted P = 1.4 × 10-6 ), while BALF contained more Bacteroidetes (29.5% vs 3.2%; adjusted P = 1.2 × 10-9 ). At the genus level several differences existed, however Streptococcus abundance was similar in both sample types (NP 37.3% vs BAL 36.1%; adjusted P = 0.8).
CONCLUSION:
Our results provide evidence that NP samples can be used to distinguish differences between children, but the relative abundance of organisms may differ between the nasopharynx and lower airway in pediatric patients. Studies utilizing NP samples as surrogates for the lower airway should be interpreted with caution
Deletion of the Stress Response Gene \u3ci\u3eDDR48\u3c/i\u3e From \u3ci\u3eHistoplasma capsulatum\u3c/i\u3e Increases Sensitivity to Oxidative Stress, Increases Susceptibility to Antifungals, and Decreases Fitness In Macrophages
The stress response gene DDR48 has been characterized in Saccharomyces cerevisiae and Candida albicans to be involved in combating various cellular stressors, from oxidative agents to antifungal compounds. Surprisingly, the biological function of DDR48 has yet to be identified, though it is likely an important part of the stress response. To gain insight into its function, we characterized DDR48 in the dimorphic fungal pathogen Histoplasma capsulatum. Transcriptional analyses showed preferential expression of DDR48 in the mycelial phase. Induction of DDR48 in Histoplasma yeasts developed after treatment with various cellular stress compounds. We generated a ddr48∆ deletion mutant to further characterize DDR48 function. Loss of DDR48 alters the transcriptional profile of the oxidative stress response and membrane synthesis pathways. Treatment with ROS or antifungal compounds reduced survival of ddr48∆ yeasts compared to controls, consistent with an aberrant cellular stress response. In addition, we infected RAW 264.7 macrophages with DDR48-expressing and ddr48∆ yeasts and observed a 50% decrease in recovery of ddr48∆ yeasts compared to wild-type yeasts. Loss of DDR48 function results in numerous negative effects in Histoplasma yeasts, highlighting its role as a key player in the global sensing and response to cellular stress by fungi
Co-culture of microalgae, cyanobacteria, and macromycetes for exopolysaccharides production: process preliminary optimization and partial characterization.
In this study, the biomass and exopolysaccharides (EPS) production in co-cultures of microalgae/cyanobacteria and macromycetes was evaluated as a technology for producing new polysaccharides for medical and/or industrial application. Based on biomass and EPS productivity of monocultures, two algae and two fungi were selected and cultured in different co-culture arrangements. The hydrosoluble EPS fractions from mono- and cocultures were characterized by ¹³C NMR spectroscopy and gas chromatography coupled to mass spectrometry and compared. It was found that co-cultures resulted in the production of an EPS different from those produced by monocultures, showing fungal predominance with microalgal/cyanobacterial traces. Co-cultures conditions were screened (temperature, agitation speed, fungal and microalgae inoculation rate, initial pH, illumination rate, and glucose concentration) in order to achieve maximum biomass and EPS production, resulting in an increase of 33 and 61% in exopolysaccharides and biomass productions, respectively (patent pending)
Dental and craniofacial defects in the Crtap−/− mouse model of osteogenesis imperfecta type VII
BackgroundInactivating mutations in the gene for cartilage‐associated protein (CRTAP) cause osteogenesis imperfecta type VII in humans, with a phenotype that can include craniofacial defects. Dental and craniofacial manifestations have not been a focus of case reports to date. We analyzed the craniofacial and dental phenotype of Crtap−/− mice by skull measurements, micro‐computed tomography (micro‐CT), histology, and immunohistochemistry.ResultsCrtap−/− mice exhibited a brachycephalic skull shape with fusion of the nasofrontal suture and facial bones, resulting in mid‐face retrusion and a class III dental malocclusion. Loss of CRTAP also resulted in decreased dentin volume and decreased cellular cementum volume, though acellular cementum thickness was increased. Periodontal dysfunction was revealed by decreased alveolar bone volume and mineral density, increased periodontal ligament (PDL) space, ectopic calcification within the PDL, bone‐tooth ankylosis, altered immunostaining of extracellular matrix proteins in bone and PDL, increased pSMAD5, and more numerous osteoclasts on alveolar bone surfaces.ConclusionsCrtap−/− mice serve as a useful model of the dental and craniofacial abnormalities seen in individuals with osteogenesis imperfecta type VII.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155878/1/dvdy166.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155878/2/dvdy166_am.pd
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Shotgun metagenomic analysis of microbial communities from the Loxahatchee nature preserve in the Florida Everglades.
BackgroundCurrently, much is unknown about the taxonomic diversity and the mechanisms of methane metabolism in the Florida Everglades ecosystem. The Loxahatchee National Wildlife Refuge is a section of the Florida Everglades that is almost entirely unstudied in regard to taxonomic profiling. This short report analyzes the metagenome of soil samples from this Refuge to investigate the predominant taxa, as well as the abundance of genes involved in environmentally significant metabolic pathways related to methane production (nitrogen fixation and dissimilatory sulfite reduction).MethodsShotgun metagenomic sequencing using the Illumina platform was performed on 17 soil samples from four different sites within the Loxahatchee National Wildlife Refuge, and underwent quality control, assembly, and annotation. The soil from each sample was tested for water content and concentrations of organic carbon and nitrogen.ResultsThe three most common phyla of bacteria for every site were Actinobacteria, Acidobacteria, and Proteobacteria; however, there was variation in relative phylum composition. The most common phylum of Archaea was Euryarchaeota for all sites. Alpha and beta diversity analyses indicated significant congruity in taxonomic diversity in most samples from Sites 1, 3, and 4 and negligible congruity between Site 2 and the other sites. Shotgun metagenomic sequencing revealed the presence of biogeochemical biomarkers of particular interest (e.g., mrcA, nifH, and dsrB) within the samples. The normalized abundances of mcrA, nifH, and dsrB exhibited a positive correlation with nitrogen concentration and water content, and a negative correlation with organic carbon concentration.ConclusionThis Everglades soil metagenomic study allowed examination of wetlands biological processes and showed expected correlations between measured organic constituents and prokaryotic gene frequency. Additionally, the taxonomic profile generated gives a basis for the diversity of prokaryotic microbial life throughout the Everglades
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