1,308 research outputs found
In situ imaging of vortices in Bose-Einstein condensates
Laboratory observations of vortex dynamics in Bose-Einstein condensates
(BECs) are essential for determination of many aspects of superfluid dynamics
in these systems. We present a novel application of dark-field imaging that
enables \texttt{\it in situ} detection of two-dimensional vortex distributions
in single-component BECs, a step towards real-time measurements of complex
two-dimensional vortex dynamics within a single BEC. By rotating a Rb
BEC in a magnetic trap, we generate a triangular lattice of vortex cores in the
BEC, with core diameters on the order of 400 nm and cores separated by
approximately 9 m. We have experimentally confirmed that the positions of
the vortex cores can be determined without the need for ballistic expansion of
the BEC.Comment: 5 pages, 4 figure
Spectral Measures of Bipartivity in Complex Networks
We introduce a quantitative measure of network bipartivity as a proportion of
even to total number of closed walks in the network. Spectral graph theory is
used to quantify how close to bipartite a network is and the extent to which
individual nodes and edges contribute to the global network bipartivity. It is
shown that the bipartivity characterizes the network structure and can be
related to the efficiency of semantic or communication networks, trophic
interactions in food webs, construction principles in metabolic networks, or
communities in social networks.Comment: 16 pages, 1 figure, 1 tabl
Evaluation of Participation and Environments for Individuals with Disabilities: An Evidence-Based Practice Project Bailey
This Evidence-Based Practice (EBP) project considered the following question: What measures are available to evaluate participation and environmental supports and barriers for individuals with disabilities and what are their psychometric properties
Near Resonant Spatial Images of Confined Bose-Einstein Condensates in the '4D' Magnetic Bottle
We present quantitative measurements of the spatial density profile of
Bose-Einstein condensates of sodium atoms confined in a new '4D' magnetic
bottle. The condensates are imaged in transmission with near resonant laser
light. We demonstrate that the Thomas-Fermi surface of a condensate can be
determined to better than 1%. More generally, we obtain excellent agreement
with mean-field theory. We conclude that precision measurements of atomic
scattering lengths and interactions between phase separated cold atoms in a
harmonic trap can be measured with high precision using this method.Comment: 15 pages, 3 figures. Submitted 10/30/97, accepted for publication in
Phys. Rev. A Rapid Com
LHS6343C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission
We report the discovery of a brown dwarf that transits one member of the M+M
binary system LHS6343AB every 12.71 days. The transits were discovered using
photometric data from the Kelper public data release. The LHS6343 stellar
system was previously identified as a single high-proper-motion M dwarf. We use
high-contrast imaging to resolve the system into two low-mass stars with masses
0.45 Msun and 0.36 Msun, respectively, and a projected separation of 55 arcsec.
High-resolution spectroscopy shows that the more massive component undergoes
Doppler variations consistent with Keplerian motion, with a period equal to the
transit period and an amplitude consistent with a companion mass of M_C = 62.8
+/- 2.3 Mjup. Based on an analysis of the Kepler light curve we estimate the
radius of the companion to be R_C = 0.832 +/- 0.021 Rjup, which is consistent
with theoretical predictions of the radius of a > 1 Gyr brown dwarf.Comment: Our previous analysis neglected the dependence of the scaled
semimajor axis, a/R, on the transit depth. By not correcting a/R for the
third-light contamination, we overestimated the mass of Star A, which led to
an overestimate the mass and radius of the LHS6343
Integrative genomic analysis reveals low T-cell infiltration as the primary feature of tobacco use in HPV-positive oropharyngeal cancer
Although tobacco use is an independent adverse prognostic feature in HPV(+) oropharyngeal squamous cell carcinoma (OPSCC), the biologic features associated with tobacco use have not been systematically investigated. We characterized genomic and immunologic features associated with tobacco use through whole exome sequencing, mRNA hybridization, and immunohistochemical staining in 47 HPV(+) OPSCC tumors. Low expression of transcripts in a T cell-inflamed gene expression profile (TGEP) was associated with tobacco use at diagnosis and lower overall and disease-free survival. Tobacco use was associated with an increased proportion of T \u3e C substitutions and a lower proportion of expected mutational signatures, but not with increases in mutational burden or recurrent oncogenic mutations. Our findings suggest that rather than increased mutational burden, tobacco\u27s primary and clinically relevant association in HPV(+) OPSCC is immunosuppression of the tumor immune microenvironment. Quantitative assays of T cell infiltration merit further study as prognostic markers in HPV(+) OPSCC
Primary bony non-Hodgkin lymphoma of the cervical spine: a case report
<p>Abstract</p> <p>Introduction</p> <p>Non-Hodgkin lymphoma primarily originating from the bone is exceedingly rare. To our knowledge, this is the first report of primary bone lymphoma presenting with progressive cord compression from an origin in the cervical spine. Herein, we discuss the unusual location in this case, the presenting symptoms, and the management of this disease.</p> <p>Case presentation</p> <p>We report on a 23-year-old Caucasian-American man who presented with two months of night sweats, fatigue, parasthesias, and progressive weakness that had progressed to near quadriplegia. Magnetic resonance (MR) imaging demonstrated significant cord compression seen primarily at C7. Surgical management, with corpectomy and dorsal segmental fusion, in combination with adjuvant chemotherapy and radiation therapy, halted the progression of the primary disease and preserved neurological function. Histological analysis demonstrated an aggressive anaplastic large cell lymphoma.</p> <p>Conclusion</p> <p>Isolated primary bony lymphoma of the spine is exceedingly rare. As in our case, the initial symptoms may be the result of progressive cervical cord compression. Anterior corpectomy with posterolateral decompression and fusion succeeded in preventing progressive neurologic decline and maintaining quality of life. The reader should be aware of the unique presentation of this disease and that surgical management is a successful treatment strategy.</p
N6-Methyladenosine Inhibits Local Ribonucleolytic Cleavage to Stabilize mRNAs in Arabidopsis
N6-methyladenosine (m6A) is a dynamic, reversible,
covalently modified ribonucleotide that occurs predominantly
toward 30 ends of eukaryotic mRNAs
and is essential for their proper function and regulation.
In Arabidopsis thaliana, many RNAs contain at
least one m6A site, yet the transcriptome-wide function
of m6A remains mostly unknown. Here, we show
that manym6A-modified mRNAs in Arabidopsis have
reduced abundance in the absence of this mark. The
decrease in abundance is due to transcript destabilization
caused by cleavage occurring 4 or 5 nt directly
upstream of unmodified m6A sites. Importantly, we
also find that, upon agriculturally relevant salt treatment,
m6A is dynamically deposited on and stabilizes
transcripts encoding proteins required for salt
and osmotic stress response. Overall, our findings
reveal that m6A generally acts as a stabilizing mark
through inhibition of site-specific cleavage in plant
transcriptomes, and this mechanism is required
for proper regulation of the salt-stress-responsive
transcriptome
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