Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems.

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Nonlinear dynamics and breakup of free-surface flows

Jets, ie collimated streams of matter, occur from the microscale up to the large-scale structure of the universe Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology They also arise from the last but one topology change of liquid masses bursting into sprays Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects

Physics of liquid jets

Climate change and fossil fuel depletion are the main reasons leading to hydrogen technology. There are many processes for hydrogen production from both conventional and alternative energy resources such as natural gas, coal, nuclear, biomass, solar and wind. In this work, a comparative overview of the major hydrogen production methods is carried out. The process descriptions along with the technical and economic aspects of 14 different production methods are discussed. An overall comparison is carried out, and the results regarding both the conventional and renewable methods are presented. The thermochemical pyrolysis and gasification are economically viable approaches providing the highest potential to become competitive on a large scale in the near future while conventional methods retain their dominant role in H2 production with costs in the range of 1.34–2.27 $/kg. Biological methods appear to be a promising pathway but further research studies are needed to improve their production rates, while the low conversion efficiencies in combination with the high investment costs are the key restrictions for water-splitting technologies to compete with conventional methods. However, further development of these technologies along with significant innovations concerning H2 storage, transportation and utilization, implies the decrease of the national dependence on fossil fuel imports and green hydrogen will dominate over the traditional energy resources.

A comparative overview of hydrogen production processes

The Commission on Classification and Terminology and the Commission on Epidemiology of the International League Against Epilepsy (ILAE) have charged a Task Force to revise concepts, definition, and classification of status epilepticus (SE). The proposed new definition of SE is as follows: Status epilepticus is a condition resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms, which lead to abnormally, prolonged seizures (after time point t1 ). It is a condition, which can have long-term consequences (after time point t2 ), including neuronal death, neuronal injury, and alteration of neuronal networks, depending on the type and duration of seizures. This definition is conceptual, with two operational dimensions: the first is the length of the seizure and the time point (t1 ) beyond which the seizure should be regarded as "continuous seizure activity." The second time point (t2 ) is the time of ongoing seizure activity after which there is a risk of long-term consequences. In the case of convulsive (tonic-clonic) SE, both time points (t1 at 5 min and t2 at 30 min) are based on animal experiments and clinical research. This evidence is incomplete, and there is furthermore considerable variation, so these time points should be considered as the best estimates currently available. Data are not yet available for other forms of SE, but as knowledge and understanding increase, time points can be defined for specific forms of SE based on scientific evidence and incorporated into the definition, without changing the underlying concepts. A new diagnostic classification system of SE is proposed, which will provide a framework for clinical diagnosis, investigation, and therapeutic approaches for each patient. There are four axes: (1) semiology; (2) etiology; (3) electroencephalography (EEG) correlates; and (4) age. Axis 1 (semiology) lists different forms of SE divided into those with prominent motor systems, those without prominent motor systems, and currently indeterminate conditions (such as acute confusional states with epileptiform EEG patterns). Axis 2 (etiology) is divided into subcategories of known and unknown causes. Axis 3 (EEG correlates) adopts the latest recommendations by consensus panels to use the following descriptors for the EEG: name of pattern, morphology, location, time-related features, modulation, and effect of intervention. Finally, axis 4 divides age groups into neonatal, infancy, childhood, adolescent and adulthood, and elderly.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/epi.13121

A Definition and Classification of Status epilepticus--Report of the ILAE Task Force on Classification of Status Epilepticus

Preliminaries.- Bell polynomials, composite structures and Gibbs partitions.- Exchangeable random partitions.- Sequential constructions of random partitions.- Poisson constructions of random partitions.- Coagulation and fragmentation processes.- Random walks and random forests.- The Brownian forest.- Brownian local times, branching and Bessel processes.- Brownian bridge asymptotics for random mappings.- Random forests and the additive coalescent.

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Combinatorial Stochastic Processes

Laminar capillary jet of viscoelastic fluid, discussing breakup, nonNewtonian jet stability and elastic properties

Breakup of a laminar capillary jet of a viscoelastic fluid

Although there are data on the duration of seizures in patients with refractory epilepsy, little is known about the duration of seizures in nonrefractory epilepsy populations. In a prospective study, seizure duration was determined in 407 children with a first unprovoked seizure using a structured interview and review of medical and ambulance records. Analysis focused on the distribution of seizure duration and on the conditional probability that a seizure would stop once it had already lasted for a specified time. Seizures lasted > or = 5 minutes in 50% of cases, > or = 10 minutes in 29%, > or = 20 minutes in 16%, and > or = 30 minutes in 12%. Seizure duration data were best fit as the sum of two exponential distributions, one with a mean of 3.6 minutes accounting for 76% of cases and the other with a mean of 31 minutes accounting for 24% of cases. The longer a seizure lasted, the less likely it was to stop within the next few minutes. In the 182 children with 2 or more seizures, the durations of the first and second seizures were highly correlated (r = 0.395, p < 0.0001). We conclude that the distribution of seizure duration in children with a first unprovoked seizure differs markedly from that observed in patients with refractory epilepsy. A subgroup of patients are predisposed to prolonged seizures. The data suggest that, once a seizure lasts for more than 5-10 minutes, it is unlikely to stop spontaneously within the next few minutes, and intervention is therefore indicated. These findings also support the continued use of the current definition of status epilepticus as a seizure lasting for 30 minutes or longer for epidemiologic studies.

How long do new-onset seizures in children last?

An improved and updated model for modern fluidized bed catalytic crackers (FCC) is presented. It is based on a more detailed kinetic description of the kinetics in both the reactor and the regenerator using the full range of published data both on FCC performance and kinetic rates. It includes a complete description of CO to CO{sub 2} combustion kinetics including the effect of catalytic combustion promoters. The model describes FCC operation in both full and partial CO combustion as well as the transition from one to the other. The reactor kinetics are based on a ten-lump model which allows feed and catalyst characterization based on laboratory experiments. The model overcomes some of the deficiencies and inadequacies of present models and is in good agreement with observed trends in industrial units.

Dynamic and control of fluidized catalytic crackers. 1: Modeling of the current generation of FCC`s

The hydrogen economy, fuel cells, and electric cars

the possibility of controlling crime.' Law makers are considering legislating heavier sentences, which raises questions about the role of prison sentences in crime prevention. Most discussions of crime and its prevention lack a way of generating quantitative estimates of what alternative policies would achieve and what they would cost. A recent paper by one of the authors (Avi-Itzhak and Shinnar, 1973) attempts to develop a mathematical model simple enough to make approximate quantitative estimates based on available statistical information. In this

Reuel Shinnar

Papers

Breakup of a laminar capillary jet of a viscoelastic fluid

How long do new-onset seizures in children last?

Dynamic and control of fluidized catalytic crackers. 1: Modeling of the current generation of FCC`s

The hydrogen economy, fuel cells, and electric cars

The Effects of the Criminal Justice System on the Control of Crime: A Quantitative Approach