339 research outputs found
Atomization of viscoelastic fluids Final report, 1 Jan. 1968 - 30 Jun. 1969
Atomization of viscoelastic fluid
Towards a Formally Verified Security Monitor for VM-based Confidential Computing
Confidential computing is a key technology for isolating high-assurance
applications from the large amounts of untrusted code typical in modern
systems. Existing confidential computing systems cannot be certified for use in
critical applications, like systems controlling critical infrastructure,
hardware security modules, or aircraft, as they lack formal verification.
This paper presents an approach to formally modeling and proving a security
monitor. It introduces a canonical architecture for virtual machine (VM)-based
confidential computing systems. It abstracts processor-specific components and
identifies a minimal set of hardware primitives required by a trusted security
monitor to enforce security guarantees. We demonstrate our methodology and
proposed approach with an example from our Rust implementation of the security
monitor for RISC-V
Kinetics of fragmentation-annihilation processes
We investigate the kinetics of systems in which particles of one species
undergo binary fragmentation and pair annihilation. In the latter, nonlinear
process, fragments react at collision to produce an inert species, causing loss
of mass. We analyse these systems in the reaction-limited regime by solving a
continuous model within the mean-field approximation. The rate of
fragmentation, for a particle of mass to break into fragments of masses
and , has the form (), and the annihilation
rate is constant and independent of the masses of the reactants. We find that
the asymptotic regime is characterized by the annihilation of small-mass
clusters. The results are compared with those for a model with linear mass-loss
(i.e.\ with a sink). We also study more complex models, in which the processes
of fragmentation and annihilation are controlled by mutually-reacting
catalysts. Both pair- and linear-annihilation are considered. Depending on the
specific model and initial densities of the catalysts, the time-decay of the
cluster-density can now be very unconventional and even non-universal. The
interplay between the intervening processes and the existence of a scaling
regime are determined by the asymptotic behaviour of the average-mass and of
the mass-density, which may either decay indefinitely or tend to a constant
value. We discuss further developments of this class of models and their
potential applications.Comment: 16 pages(LaTeX), submitted to Phys. Rev.
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Regression, developmental trajectory and associated problems in disorders in the autism spectrum: the SNAP study
We report rates of regression and associated findings in a population derived group of 255 children aged 9-14 years, participating in a prevalence study of autism spectrum disorders (ASD); 53 with narrowly defined autism, 105 with broader ASD and 97 with non-ASD neurodevelopmental problems, drawn from those with special educational needs within a population of 56,946 children. Language regression was reported in 30% with narrowly defined autism, 8% with broader ASD and less than 3% with developmental problems without ASD. A smaller group of children were identified who underwent a less clear setback. Regression was associated with higher rates of autistic symptoms and a deviation in developmental trajectory. Regression was not associated with epilepsy or gastrointestinal problems
MRI Discriminates Thrombus Composition and ST Resolution after Percutaneous Coronary Intervention in Patients with ST-Elevation Myocardial Infarction
Histological composition of material obtained by thrombus aspiration during percutaneous coronary intervention (PCI) in patients with ST-segment elevation acute myocardial infarction (STEMI) is highly variable. We aimed to characterize this material using magnetic resonance imaging (MRI) and to correlate MRI findings with the success of PCI in terms of ST-segment resolution. Thrombus aspiration during primary or rescue PCI was attempted in 100 consecutive STEMI patients, of whom enough material for MRI was obtained in 59. MR images were obtained at 9.4T and T1 and T2 values were measured. Patients with (nâ=â31) and without (nâ=â28) adequate ST resolution 120 min after PCI (â„70% of pre-PCI value) had similar baseline characteristics except for a higher prevalence of diabetes mellitus in the latter (10 vs. 43%, pâ=â0.003). T1 values were similar in both groups (1248±112 vs. 1307±85 ms, respectively, pâ=â0.7). T2 values averaged 31.2±10.3 and 36.6±12.2 ms; in thrombus from patients with and without adequate ST resolution (pâ=â0.09). After adjusting for diabetes and other baseline characteristics, lower T2 values were significantly associated with inadequate ST resolution (odds ratio for 1 ms increase 1.08, CI 95% 1.01â1.16, pâ=â0.027). Histology classified thrombus in 3 groups: coagulated blood (nâ=â38), fibrin rich (nâ=â9) and lipid-rich (nâ=â3). Thrombi composed mostly of coagulated blood were characterized as being of short (nâ=â10), intermediate (nâ=â15) or long evolution (nâ=â13), T2 values being 34.0±13.2, 31.9±8.3 and 31.5±7.9 ms respectively (pâ=âNS). In this subgroup, T2 was significantly higher in specimens from patients with inadequate perfusion (35.9±10.3 versus 28.6±6.7 ms, pâ=â0.02). This can be of clinical interest as it provides information on the probability of adequate ST resolution, a surrogate for effective myocardial reperfusion
What is the easier and more reliable dose calculation for iv Phenytoin in children at risk of developing convulsive status epilepticus, 18 mg/kg or 20 mg/kg?
Background: With the Convulsive Status Guidelines due for renewal, we wondered if a phenytoin dose of â20 mg/kgâ
would be easier to calculate correctly and therefore safer than the current â18 mg/kgâ. An educational exercise in dose
calculation was therefore undertaken to assess ease of calculation.
Method: A standard question paper was prepared, comprising five clinical scenarios with children of varying ages and
estimated body weights. Medical students, trainee doctors at registrar and senior house officer level, and consultant
paediatricians were asked to complete the exercise, in private, by one of two medical students (SD, PS). Calculations were done with and without a calculator, for 18 mg/kg and for 20 mg/kg in randomised order. Speed and errors (greater than 10%) were determined. The data analysis was performed using SPSS version 18.
Results: All answered all 20 scenarios, giving a total of 300 answers per doctor/student group, and 300 answers per
type of calculation. When comparing the 2 doses, the numbers of errors more than 10% were significantly less in
20 mg/kg dose (0.33%) as compared to the 18 mg/kg dose (9.3%) (p<0.0001). Speed off calculation was significantly
decreased in 20 mg/kg dose when compared with 18 mg/kg dose, with (p<0.001) or without (p<0.0001) the calculator.
Speed was more than halved and errors were much less frequent by using a calculator, for the 18 mg/kg dose but no
difference with or without the calculator for 20 mg/kg dose.
Conclusion: We recommend that the future guidelines should suggest iv Phenytoin at 20 mg/kg rather than 18 mg/kg.
This will make the calculation easier and reduce the risk of significant errors
The association of patient weight and dose of fosphenytoin, levetiracetam, and valproic acid with treatment success in status epilepticus
The Established Status Epilepticus Treatment Trial was a blinded, comparativeâeffectiveness study of fosphenytoin, levetiracetam, and valproic acid in benzodiazepineârefractory status epilepticus. The primary outcome was clinical seizure cessation and increased responsiveness without additional anticonvulsant medications. Weightâbased dosing was capped at 75 kg. Hence, patients weighing >75 kg received a lower mg/kg dose. Logistic regression models were developed in 235 adults to determine the association of weight (†or >75 kg, †or >90 kg), sex, treatment, and weightânormalized dose with the primary outcome and solely seizure cessation. The primary outcome was achieved in 45.1% and 42.5% of those â€75 kg and >75 kg, respectively. Using univariate analyses, the likelihood of success for those >75 kg (odds ratio [OR] = 0.9, 95% confidence interval [CI] = 0.54â1.51) or >90 kg (OR = 0.85, 95% CI = 0.42â1.66) was not statistically different compared with those â€75 kg or â€90 kg, respectively. Similarly, other predictors were not significantly associated with primary outcome or clinical seizure cessation. Our findings suggest that doses, capped at 75 kg, likely resulted in concentrations greater than those needed for outcome. Studies that include drug concentrations and heavier individuals are needed to confirm these findings
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