562 research outputs found
Phenomenology of Sterile Neutrinos
The indications in favor of short-baseline neutrino oscillations, which
require the existence of one or more sterile neutrinos, are reviewed. In the
framework of 3+1 neutrino mixing, which is the simplest extension of the
standard three-neutrino mixing which can partially explain the data, there is a
strong tension in the interpretation of the data, mainly due to an
incompatibility of the results of appearance and disappearance experiments. In
the framework of 3+2 neutrino mixing, CP violation in short-baseline
experiments can explain the difference between MiniBooNE neutrino and
antineutrino data, but the tension between the data of appearance and
disappearance experiments persists because the short-baseline disappearance of
electron antineutrinos and muon neutrinos compatible with the LSND and
MiniBooNE antineutrino appearance signal has not been observed.Comment: 8 pages. Invited paper to NUFACT 11, XIIIth International Workshop on
Neutrino Factories, Super beams and Beta beams, 1-6 August 2011, CERN and
University of Geneva (Submitted to IOP conference series
Penetration depth of low-coherence enhanced backscattered light in sub-diffusion regime
The mechanisms of photon propagation in random media in the diffusive
multiple scattering regime have been previously studied using diffusion
approximation. However, similar understanding in the low-order (sub-diffusion)
scattering regime is not complete due to difficulties in tracking photons that
undergo very few scatterings events. Recent developments in low-coherence
enhanced backscattering (LEBS) overcome these difficulties and enable probing
photons that travel very short distances and undergo only a few scattering
events. In LEBS, enhanced backscattering is observed under illumination with
spatial coherence length L_sc less than the scattering mean free path l_s. In
order to understand the mechanisms of photon propagation in LEBS in the
subdiffusion regime, it is imperative to develop analytical and numerical
models that describe the statistical properties of photon trajectories. Here we
derive the probability distribution of penetration depth of LEBS photons and
report Monte Carlo numerical simulations to support our analytical results. Our
results demonstrate that, surprisingly, the transport of photons that undergo
low-order scattering events has only weak dependence on the optical properties
of the medium (l_s and anisotropy factor g) and strong dependence on the
spatial coherence length of illumination, L_sc, relative to those in the
diffusion regime. More importantly, these low order scattering photons
typically penetrate less than l_s into the medium due to low spatial coherence
length of illumination and their penetration depth is proportional to the
one-third power of the coherence volume (i.e. [l_s \pi L_sc^2 ]^1/3).Comment: 32 pages(including 7 figures), modified version to appear in Phys.
Rev.
Outcomes of interfacility critical care adult patient transport: a systematic review
INTRODUCTION: We aimed to determine the adverse events and important prognostic factors associated with interfacility transport of intubated and mechanically ventilated adult patients. METHODS: We performed a systematic review of MEDLINE, CENTRAL, EMBASE, CINAHL, HEALTHSTAR, and Web of Science (from inception until 10 January 2005) for all clinical studies describing the incidence and predictors of adverse events in intubated and mechanically ventilated adult patients undergoing interfacility transport. The bibliographies of selected articles were also examined. RESULTS: Five studies (245 patients) met the inclusion criteria. All were case-series and two were prospective in design. Due to the paucity of studies and significant heterogeneity in study population, outcome events, and results, we synthesized data in a qualitative manner. Pre-transport severity of illness was reported in only one study. The most common indication for transport was a need for investigations and/or specialist care (three studies, 220 patients). Transport modalities included air (fixed or rotor wing; 66% of patients) and ground (31%) ambulance, and commercial aircraft (3%). Transport teams included a physician in three studies (220 patients). Death during transfer was rare (n = 1). No other adverse events or significant therapeutic interventions during transport were reported. One study reported a 19% (28/145) incidence of respiratory alkalosis on arrival and another study documented a 30% overall intensive care unit mortality, while no adverse events or outcomes were reported after arrival in the three other studies. CONCLUSION: Insufficient data exist to draw firm conclusions regarding the mortality, morbidity, or risk factors associated with the interfacility transport of intubated and mechanically ventilated adult patients. Further study is required to define the risks and benefits of interfacility transfer in this patient population. Such information is important for the planning and allocation of resources related to transporting critically ill adults
A retrospective cohort pilot study to evaluate a triage tool for use in a pandemic
Abstract
Introduction
The objective of this pilot study was to assess the usability of the draft Ontario triage protocol, to estimate its potential impact on patient outcomes, and ability to increase resource availability based on a retrospective cohort of critically ill patients cared for during a non-pandemic period.
Methods
Triage officers applied the protocol prospectively to 2 retrospective cohorts of patients admitted to 2 academic medical/surgical ICUs during an 8 week period of peak occupancy. Each patient was assigned a treatment priority (red -- 'highest', yellow -- 'intermediate', green -- 'discharge to ward', or blue/black -- 'expectant') by the triage officers at 3 separate time points (at the time of admission to the ICU, 48, and 120 hours post admission).
Results
Overall, triage officers were either confident or very confident in 68.4% of their scores; arbitration was required in 54.9% of cases. Application of the triage protocol would potentially decrease the number of required ventilator days by 49.3% (568 days) and decrease the total ICU days by 52.6% (895 days). On the triage protocol at ICU admission the survival rate in the red (93.7%) and yellow (62.5%) categories were significantly higher then that of the blue category (24.6%) with associated P values of < 0.0001 and 0.0003 respectively. Further, the survival rate of the red group was significantly higher than the overall survival rate of 70.9% observed in the cohort (P < 0.0001). At 48 and 120 hours, survival rates in the blue group increased but remained lower then the red or yellow groups.
Conclusions
Refinement of the triage protocol and implementation is required prior to future study, including improved training of triage officers, and protocol modification to minimize the exclusion from critical care of patients who may in fact benefit. However, our results suggest that the triage protocol can help to direct resources to patients who are most likely to benefit, and help to decrease the demands on critical care resources, thereby making available more resources to treat other critically ill patients
Random paths and current fluctuations in nonequilibrium statistical mechanics
An overview is given of recent advances in nonequilibrium statistical
mechanics about the statistics of random paths and current fluctuations.
Although statistics is carried out in space for equilibrium statistical
mechanics, statistics is considered in time or spacetime for nonequilibrium
systems. In this approach, relationships have been established between
nonequilibrium properties such as the transport coefficients, the thermodynamic
entropy production, or the affinities, and quantities characterizing the
microscopic Hamiltonian dynamics and the chaos or fluctuations it may generate.
This overview presents results for classical systems in the escape-rate
formalism, stochastic processes, and open quantum systems
An exact analytical solution for generalized growth models driven by a Markovian dichotomic noise
Logistic growth models are recurrent in biology, epidemiology, market models,
and neural and social networks. They find important applications in many other
fields including laser modelling. In numerous realistic cases the growth rate
undergoes stochastic fluctuations and we consider a growth model with a
stochastic growth rate modelled via an asymmetric Markovian dichotomic noise.
We find an exact analytical solution for the probability distribution providing
a powerful tool with applications ranging from biology to astrophysics and
laser physics
How Stands Collapse II
I review ten problems associated with the dynamical wave function collapse
program, which were described in the first of these two papers. Five of these,
the \textit{interaction, preferred basis, trigger, symmetry} and
\textit{superluminal} problems, were discussed as resolved there. In this
volume in honor of Abner Shimony, I discuss the five remaining problems,
\textit{tails, conservation law, experimental, relativity, legitimization}.
Particular emphasis is given to the tails problem, first raised by Abner. The
discussion of legitimization contains a new argument, that the energy density
of the fluctuating field which causes collapse should exert a gravitational
force. This force can be repulsive, since this energy density can be negative.
Speculative illustrations of cosmological implications are offered.Comment: 37 page
Ongoing clinical trials and treatment options for patients with systemic sclerosis-associated interstitial lung disease
SSc is a rare CTD that affects multiple organ systems, resulting in substantial morbidity and mortality. Evidence of interstitial lung disease (ILD) is seen in âŒ80% of patients with SSc. Currently there is no approved disease-modifying treatment for ILD and few effective treatment options are available. CYC is included in treatment guidelines, but it has limited efficacy and is associated with toxicity. MMF is becoming the most commonly used medication in clinical practice in North America and the UK, but its use is not universal. Newer agents targeting the pathogenic mechanisms underlying SSc-ILD, including fibrotic and inflammatory pathways, lymphocytes, cell-cell and cell-extracellular membrane interactions, hold promise for better treatment outcomes, including improved lung function, patient-related outcomes and quality of life. Here we review ongoing trials of established and novel agents that are currently recruiting patients with SSc-ILD
Efficacy and Safety of Atacicept in Patients With Systemic Lupus Erythematosus: Results of a TwentyâFourâWeek, Multicenter, Randomized, DoubleâBlind, PlaceboâControlled, ParallelâArm, Phase IIb Study
OBJECTIVE: To evaluate the efficacy and safety of atacicept, an antagonist of BLyS/APRIL-mediated B cell activation, in patients with systemic lupus erythematosus (SLE).
METHODS: ADDRESS II was a phase IIb, multicentre study (NCT01972568). Patients with active, autoantibody-positive SLE receiving standard therapy were randomized (1:1:1) to atacicept (75 or 150 mg) or placebo for 24 weeks. The primary endpoint was the SLE responder index (SRI)-4 at Week 24.
RESULTS: The ITT population included 306 patients. There was a trend towards improved SRI-4 response rate with atacicept 75 mg (57.8% [adjusted OR 1.78], P = 0.045) and 150 mg (53.8% [adjusted OR 1.56], P = 0.121) versus placebo (44.0%) at Week 24 (primary analysis; screening visit as baseline). In a pre-specified sensitivity analysis using study Day 1 as baseline, a significantly larger proportion of patients receiving atacicept 75 mg (55.9% [adjusted OR 1.88], P = 0.029) and 150 mg (55.8% [adjusted OR 1.96], P = 0.020) achieved SRI-4 response at Week 24 versus placebo (41%). In pre-defined subpopulations with baseline high disease activity (HDA), serologically active disease (SA), or both, statistically significant improvements in SRI-4 and SRI-6 response rates were seen with atacicept versus placebo. Severe flare risk was reduced with atacicept in both the ITT and HDA populations. The risks of serious adverse events and serious or severe infection were not increased with atacicept versus placebo. CONCLUSION: Atacicept showed evidence of efficacy in SLE, particularly in HDA and SA patients. Reductions in disease activity and severe flare were observed with atacicept treatment, along with an acceptable safety profile
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