3,179 research outputs found
Rigorous Derivation of the Gross-Pitaevskii Equation
The time dependent Gross-Pitaevskii equation describes the dynamics of
initially trapped Bose-Einstein condensates. We present a rigorous proof of
this fact starting from a many-body bosonic Schroedinger equation with a short
scale repulsive interaction in the dilute limit. Our proof shows the
persistence of an explicit short scale correlation structure in the condensate.Comment: 4 pages, 1 figur
Biodistribution and PET Imaging of pharmacokinetics of manganese in mice using Manganese-52
<div><p>Manganese is essential to life, and humans typically absorb sufficient quantities of this element from a normal healthy diet; however, chronic, elevated ingestion or inhalation of manganese can be neurotoxic, potentially leading to <i>manganism</i>. Although imaging of large amounts of accumulated Mn(II) is possible by MRI, quantitative measurement of the biodistribution of manganese, particularly at the trace level, can be challenging. In this study, we produced the positron-emitting radionuclide <sup>52</sup>Mn (<i>t</i><sub><i>1/2</i></sub> = 5.6 d) by proton bombardment (<i>E</i><sub><i>p</i></sub><15 MeV) of chromium metal, followed by solid-phase isolation by cation-exchange chromatography. An aqueous solution of [<sup>52</sup>Mn]MnCl<sub>2</sub> was nebulized into a closed chamber with openings through which mice inhaled the aerosol, and a separate cohort of mice received intravenous (IV) injections of [<sup>52</sup>Mn]MnCl<sub>2</sub>. <i>Ex vivo</i> biodistribution was performed at 1 h and 1 d post-injection/inhalation (p.i.). In both trials, we observed uptake in lungs and thyroid at 1 d p.i. Manganese is known to cross the blood-brain barrier, as confirmed in our studies following IV injection (0.86%ID/g, 1 d p.i.) and following inhalation of aerosol, (0.31%ID/g, 1 d p.i.). Uptake in salivary gland and pancreas were observed at 1 d p.i. (0.5 and 0.8%ID/g), but to a much greater degree from IV injection (6.8 and 10%ID/g). In a separate study, mice received IV injection of an imaging dose of [<sup>52</sup>Mn]MnCl<sub>2</sub>, followed by <i>in vivo</i> imaging by positron emission tomography (PET) and <i>ex vivo</i> biodistribution. The results from this study supported many of the results from the biodistribution-only studies. In this work, we have confirmed results in the literature and contributed new results for the biodistribution of inhaled radiomanganese for several organs. Our results could serve as supporting information for environmental and occupational regulations, for designing PET studies utilizing <sup>52</sup>Mn, and/or for predicting the biodistribution of manganese-based MR contrast agents.</p></div
Efficient growth of complex graph states via imperfect path erasure
Given a suitably large and well connected (complex) graph state, any quantum
algorithm can be implemented purely through local measurements on the
individual qubits. Measurements can also be used to create the graph state:
Path erasure techniques allow one to entangle multiple qubits by determining
only global properties of the qubits. Here, this powerful approach is extended
by demonstrating that even imperfect path erasure can produce the required
graph states with high efficiency. By characterizing the degree of error in
each path erasure attempt, one can subsume the resulting imperfect entanglement
into an extended graph state formalism. The subsequent growth of the improper
graph state can be guided, through a series of strategic decisions, in such a
way as to bound the growth of the error and eventually yield a high-fidelity
graph state. As an implementation of these techniques, we develop an analytic
model for atom (or atom-like) qubits in mismatched cavities, under the
double-heralding entanglement procedure of Barrett and Kok [Phys. Rev. A 71,
060310 (2005)]. Compared to straightforward postselection techniques our
protocol offers a dramatic improvement in growing complex high-fidelity graph
states.Comment: 15 pages, 10 figures (which print to better quality than when viewed
as an on screen pdf
Optimal combinations of imperfect objects
We address the question of how to make best use of imperfect objects, such as
defective analog and digital components. We show that perfect, or near-perfect,
devices can be constructed by taking combinations of such defects. Any
remaining objects can be recycled efficiently. In addition to its practical
applications, our `defect combination problem' provides a novel generalization
of classical optimization problems.Comment: 4 pages, 3 figures, minor change
Recommended from our members
Metabolic correlates of prevalent mild cognitive impairment and Alzheimer's disease in adults with Down syndrome.
IntroductionDisruption of metabolic function is a recognized feature of late onset Alzheimer's disease (LOAD). We sought to determine whether similar metabolic pathways are implicated in adults with Down syndrome (DS) who have increased risk for Alzheimer's disease (AD).MethodsWe examined peripheral blood from 292 participants with DS who completed baseline assessments in the Alzheimer's Biomarkers Consortium-Down Syndrome (ABC-DS) using untargeted mass spectrometry (MS). Our sample included 38 individuals who met consensus criteria for AD (DS-AD), 43 who met criteria for mild cognitive impairment (DS-MCI), and 211 who were cognitively unaffected and stable (CS).ResultsWe measured relative abundance of 8,805 features using MS and 180 putative metabolites were differentially expressed (DE) among the groups at false discovery rate-corrected q< 0.05. From the DE features, a nine-feature classifier model classified the CS and DS-AD groups with receiver operating characteristic area under the curve (ROC AUC) of 0.86 and a two-feature model classified the DS-MCI and DS-AD groups with ROC AUC of 0.88. Metabolite set enrichment analysis across the three groups suggested alterations in fatty acid and carbohydrate metabolism.DiscussionOur results reveal metabolic alterations in DS-AD that are similar to those seen in LOAD. The pattern of results in this cross-sectional DS cohort suggests a dynamic time course of metabolic dysregulation which evolves with clinical progression from non-demented, to MCI, to AD. Metabolomic markers may be useful for staging progression of DS-AD
Brokered Graph State Quantum Computing
We describe a procedure for graph state quantum computing that is tailored to
fully exploit the physics of optically active multi-level systems. Leveraging
ideas from the literature on distributed computation together with the recent
work on probabilistic cluster state synthesis, our model assigns to each
physical system two logical qubits: the broker and the client. Groups of
brokers negotiate new graph state fragments via a probabilistic optical
protocol. Completed fragments are mapped from broker to clients via a simple
state transition and measurement. The clients, whose role is to store the
nascent graph state long term, remain entirely insulated from failures during
the brokerage. We describe an implementation in terms of NV-centres in diamond,
where brokers and clients are very naturally embodied as electron and nuclear
spins.Comment: 5 pages, 3 figure
Pathway Commons, a web resource for biological pathway data
Pathway Commons (http://www.pathwaycommons.org) is a collection of publicly available pathway data from multiple organisms. Pathway Commons provides a web-based interface that enables biologists to browse and search a comprehensive collection of pathways from multiple sources represented in a common language, a download site that provides integrated bulk sets of pathway information in standard or convenient formats and a web service that software developers can use to conveniently query and access all data. Database providers can share their pathway data via a common repository. Pathways include biochemical reactions, complex assembly, transport and catalysis events and physical interactions involving proteins, DNA, RNA, small molecules and complexes. Pathway Commons aims to collect and integrate all public pathway data available in standard formats. Pathway Commons currently contains data from nine databases with over 1400 pathways and 687â000 interactions and will be continually expanded and updated
Optical generation of matter qubit graph states
We present a scheme for rapidly entangling matter qubits in order to create
graph states for one-way quantum computing. The qubits can be simple 3-level
systems in separate cavities. Coupling involves only local fields and a static
(unswitched) linear optics network. Fusion of graph state sections occurs with,
in principle, zero probability of damaging the nascent graph state. We avoid
the finite thresholds of other schemes by operating on two entangled pairs, so
that each generates exactly one photon. We do not require the relatively slow
single qubit local flips to be applied during the growth phase: growth of the
graph state can then become a purely optical process. The scheme naturally
generates graph states with vertices of high degree and so is easily able to
construct minimal graph states, with consequent resource savings. The most
efficient approach will be to create new graph state edges even as qubits
elsewhere are measured, in a `just in time' approach. An error analysis
indicates that the scheme is relatively robust against imperfections in the
apparatus.Comment: 10 pages in 2 column format, includes 4 figures. Problems with
figures resolve
The American Association for the Surgery of Trauma renal injury grading scale: Implications of the 2018 revisions for injury reclassification and predicting bleeding interventions.
BackgroundIn 2018, the American Association for the Surgery of Trauma (AAST) published revisions to the renal injury grading system to reflect the increased reliance on computed tomography scans and non-operative management of high-grade renal trauma (HGRT). We aimed to evaluate how these revisions will change the grading of HGRT and if it outperforms the original 1989 grading in predicting bleeding control interventions.MethodsData on HGRT were collected from 14 Level-1 trauma centers from 2014 to 2017. Patients with initial computed tomography scans were included. Two radiologists reviewed the scans to regrade the injuries according to the 1989 and 2018 AAST grading systems. Descriptive statistics were used to assess grade reclassifications. Mixed-effect multivariable logistic regression was used to measure the predictive ability of each grading system. The areas under the curves were compared.ResultsOf the 322 injuries included, 27.0% were upgraded, 3.4% were downgraded, and 69.5% remained unchanged. Of the injuries graded as III or lower using the 1989 AAST, 33.5% were upgraded to grade IV using the 2018 AAST. Of the grade V injuries, 58.8% were downgraded using the 2018 AAST. There was no statistically significant difference in the overall areas under the curves between the 2018 and 1989 AAST grading system for predicting bleeding interventions (0.72 vs. 0.68, p = 0.34).ConclusionAbout one third of the injuries previously classified as grade III will be upgraded to grade IV using the 2018 AAST, which adds to the heterogeneity of grade IV injuries. Although the 2018 AAST grading provides more anatomic details on injury patterns and includes important radiologic findings, it did not outperform the 1989 AAST grading in predicting bleeding interventions.Level of evidencePrognostic and Epidemiological Study, level III
Postoperative vacuum therapy following AMSâą LGX 700Âź inflatable penile prosthesis placement: penile dimension outcomes and overall satisfaction
Penile shortening after inflatable penile prosthesis for erectile dysfunction is a common postoperative patient complaint and
can reduce overall satisfaction with the procedure. In this prospective study we report our results regarding penile
dimensions and patient satisfaction outcomes after 1 year of follow-up from AMSâąLGX700Âź penile prosthesis implant with
6 months of vacuum erectile device therapy. Seventy-four selected patients with medically refractory erectile dysfunction
underwent AMSâą LGX 700Âź IPP placement. Postoperatively, patients were assigned vacuum device therapy for 5 min
twice daily. Follow-up continued for 1 year after surgery. Dimensional and functional results were assessed. Baseline
median preoperative stretched penile length and girth were 14 cm (range 10â17) and 9 cm (range 7â12), respectively. At the
end of the study penile median dimensional outcomes were 17 cm (range 13â23) for length and 11 cm (range 10â13) for
girth while a median number of 24 pumps (range 18â29) to fully inflate the device was seen. Baseline median International
Index of Erectile Function (IIEF-5) score was 9 (range 5â11), at 6 months 20 (range 18â26) and at 1 year was 25 (range
20â27) (p < 0.0001). Median Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) score at the end of the
follow-up was 74 (range 66â78). Our postoperative rehabilitation program is feasible and should be recommended after
prothesis surgery in order to increase overall satisfaction with the procedure. Penile postoperative dimensional outcomes
were statistically significant improved and complications were negligible
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