1,507 research outputs found
Dynamical Quantum Error Correction of Unitary Operations with Bounded Controls
Dynamically corrected gates were recently introduced [Khodjasteh and Viola,
Phys. Rev. Lett. 102, 080501 (2009)] as a tool to achieve decoherence-protected
quantum gates based on open-loop Hamiltonian engineering. Here, we further
expand the framework of dynamical quantum error correction, with emphasis on
elucidating under what conditions decoherence suppression can be ensured while
performing a generic target quantum gate, using only available bounded-strength
control resources. Explicit constructions for physically relevant error models
are detailed, including arbitrary linear decoherence and pure dephasing on
qubits. The effectiveness of dynamically corrected gates in an illustrative
non-Markovian spin-bath setting is investigated numerically, confirming the
expected fidelity performance in a wide parameter range. Robutness against a
class of systematic control errors is automatically incorporated in the
perturbative error regime.Comment: 21 pages, 7 figures (errors fixed, figures added, text updated
Involving community health workers in disease-specific interventions: perspectives from The Gambia on the impact of this approach
Background
The Community Health Worker (CHW) programme is recognised as key for providing healthcare to communities, particularly in remote locations. CHWs are usually volunteers, nominated by their communities and trained to provide basic care and prevention for common illnesses. However, differences in disease-specific programmes aimed at meeting national agenda and perceived health needs of the community raises questions about the best approach to maximise the potential of this workforce.
Methods
This was an explorative qualitative study, ancillary to a larger trial on a malaria control intervention. In July 2017, 40 semi-structured interviews were conducted with 17 village health workers (VHWs), four community health nurses who supervise VHWs, and 19 key informants from the community. Analysis was concurrent to data collection and carried out using a deductive process for thematic analysis, with the aid of NVivo 11 Qualitative Analysis Software.
Results
There were three key aspects of the VHW role identified in this setting; (1) to give health advice; (2) to treat and refer patients; and (3) to support environmental cleaning. The VHWs’ involvement in the clinical trial impacted their role in several ways. Overall, this was perceived very positively by the community and the VHWs since it improved access to medication and training on how to treat malaria. However, involvement was also perceived to increase VHWs’ workload, and placed more emphasis on malaria over other common illnesses, creating a shift in the balance of their role between disease prevention and treatment.
Conclusions
VHWs are essential for the successful delivery of disease-specific activities at the community level. However, involving them in these activities has important implications for their everyday role. If carefully managed, it has the potential to improve their capacity to screen and treat specific diseases such as malaria
Convergence to equilibrium for many particle systems
The goal of this paper is to give a short review of recent results of the
authors concerning classical Hamiltonian many particle systems. We hope that
these results support the new possible formulation of Boltzmann's ergodicity
hypothesis which sounds as follows. For almost all potentials, the minimal
contact with external world, through only one particle of , is sufficient
for ergodicity. But only if this contact has no memory. Also new results for
quantum case are presented
The Cross Section of 3He(3He,2p)4He measured at Solar Energies
We report on the results of the \hethet\ experiment at the underground
accelerator facility LUNA (Gran Sasso). For the first time the lowest
projectile energies utilized for the cross section measurement correspond to
energies below the center of the solar Gamow peak (=22 keV). The
data provide no evidence for the existence of a hypothetical resonance in the
energy range investigated. Although no extrapolation is needed anymore (except
for energies at the low-energy tail of the Gamow peak), the data must be
corrected for the effects of electron screening, clearly observed the first
time for the \hethet\ reaction. The effects are however larger than expected
and not understood, leading presently to the largest uncertainty on the quoted
value for bare nuclides (=5.40 MeV b).Comment: 18 pages, 10 postscript figures, Calculations concerning hypothetical
resonanz added, Submitted to Phys. Rev. C., available at this URL:
HTTP://www.lngs.infn.it/lngs/htexts/luna/luna.htm
AltitudeOmics: Red Blood Cell metabolic adaptation to high altitude hypoxia
Red blood cells (RBCs) are key players in systemic oxygen transport. RBCs respond to in vitro hypoxia through the so-called oxygen-dependent metabolic regulation, which involves the competitive binding of deoxyhemoglobin and glycolytic enzymes to the N-terminal cytosolic domain of band 3. This mechanism promotes the accumulation of 2,3-DPG, stabilizing the deoxygenated state of hemoglobin, and cytosol acidification, triggering oxygen off-loading through the Bohr effect. Despite in vitro studies, in vivo adaptations to hypoxia have not yet been completely elucidated. Within the framework of the AltitudeOmics study, erythrocytes were collected from 21 healthy volunteers at sea level, after exposure to high altitude (5260m) for 1, 7 and 16days, and following reascent after 7days at 1525m. UHPLC-MS metabolomics results were correlated to physiological and athletic performance parameters. Immediate metabolic adaptations were noted as early as a few hours from ascending to >5000m, and maintained for 16 days at high altitude. Consistent with the mechanisms elucidated in vitro, hypoxia promoted glycolysis and deregulated the pentose phosphate pathway, as well purine catabolism, glutathione homeostasis, arginine/nitric oxide and sulphur/H2S metabolism. Metabolic adaptations were preserved one week after descent, consistently with improved physical performances in comparison to the first ascendance, suggesting a mechanism of metabolic memory
Temporal fluctuations of waves in weakly nonlinear disordered media
We consider the multiple scattering of a scalar wave in a disordered medium
with a weak nonlinearity of Kerr type. The perturbation theory, developed to
calculate the temporal autocorrelation function of scattered wave, fails at
short correlation times. A self-consistent calculation shows that for
nonlinearities exceeding a certain threshold value, the multiple-scattering
speckle pattern becomes unstable and exhibits spontaneous fluctuations even in
the absence of scatterer motion. The instability is due to a distributed
feedback in the system "coherent wave + nonlinear disordered medium". The
feedback is provided by the multiple scattering. The development of instability
is independent of the sign of nonlinearity.Comment: RevTeX, 15 pages (including 5 figures), accepted for publication in
Phys. Rev.
Coagulation Factor Xa Induces Proinflammatory Responses in Cardiac Fibroblasts via Activation of Protease-Activated Receptor-1
Coagulation factor (F) Xa induces proinflammatory responses through activation of protease-activated receptors (PARs). However, the effect of FXa on cardiac fibroblasts (CFs) and the contribution of PARs in FXa-induced cellular signalling in CF has not been fully characterised. To answer these questions, human and rat CFs were incubated with FXa (or TRAP-14, PAR-1 agonist). Gene expression of pro-fibrotic and proinflammatory markers was determined by qRT-PCR after 4 and 24 h. Gene silencing of F2R (PAR-1) and F2RL1 (PAR-2) was achieved using siRNA. MCP-1 protein levels were measured by ELISA of FXa-conditioned media at 24 h. Cell proliferation was assessed after 24 h of incubation with FXa ± SCH79797 (PAR-1 antagonist). In rat CFs, FXa induced upregulation of Ccl2 (MCP-1; >30-fold at 4 h in atrial and ventricular CF) and Il6 (IL-6; ±7-fold at 4 h in ventricular CF). Increased MCP-1 protein levels were detected in FXa-conditioned media at 24 h. In human CF, FXa upregulated the gene expression of CCL2 (>3-fold) and IL6 (>4-fold) at 4 h. Silencing of F2R (PAR-1 gene), but not F2RL1 (PAR-2 gene), downregulated this effect. Selective activation of PAR-1 by TRAP-14 increased CCL2 and IL6 gene expression; this was prevented by F2R (PAR-1 gene) knockdown. Moreover, SCH79797 decreased FXa-induced proliferation after 24 h. In conclusion, our study shows that FXa induces overexpression of proinflammatory genes in human CFs via PAR-1, which was found to be the most abundant PARs isoform in this cell type
Impact of intra-partum azithromycin on carriage of group A streptococcus in the Gambia: a posthoc analysis of a double-blind randomized placebo-controlled trial
Background:
Group A Streptococcus (GAS) is a major human pathogen and an important cause of maternal and neonatal sepsis. Asymptomatic bacterial colonization is considered a necessary step towards sepsis. Intra-partum azithromycin may reduce GAS carriage.
Methods:
A posthoc analysis of a double-blind, placebo-controlled randomized-trial was performed to determine the impact of 2 g oral dose of intra-partum azithromycin on maternal and neonatal GAS carriage and antibiotic resistance. Following screening, 829 mothers were randomized who delivered 843 babies. GAS was determined by obtaining samples from the maternal and newborn nasopharynx, maternal vaginal tract and breastmilk. Whole Genome Sequencing (WGS) of GAS isolates was performed using the Illumina Miseq platform.
Results:
GAS carriage was lower in the nasopharynx of both mothers and babies and breast milk among participants in the azithromycin arm. No differences in GAS carriage were found between groups in the vaginal tract. The occurrence of azithromycin-resistant GAS was similar in both arms, except for a higher prevalence in the vaginal tract among women in the azithromycin arm. WGS revealed all macrolide-resistant vaginal tract isolates from the azithromycin arm were Streptococcus dysgalactiae subspecies equisimilis expressing Lancefield group A carbohydrate (SDSE(A)) harbouring macrolide resistant genes msr(D) and mef(A). Ten of the 45 GAS isolates (22.2%) were SDSE(A).
Conclusions:
Oral intra-partum azithromycin reduced GAS carriage among Gambian mothers and neonates however carriage in the maternal vaginal tract was not affected by the intervention due to azithromycin resistant SDSE(A). SDSE(A) resistance must be closely monitored to fully assess the public health impact of intrapartum azithromycin on GAS.
Trial registration: ClinicalTrials.gov Identifier: NCT0180094
- …