Tip-splitting evolution in the idealized Saffman-Taylor problem

We derive a formula describing the evolution of tip-splittings of Saffman-Taylor fingers in a Hele-Shaw cell, at zero surface tension

Kajian Desain Environmental Graphic Design Umeda Hospital

Environmental graphic design (EGD) adalah sebuah obyek desain grafis yang belum banyak dibahas karena seringkali dinilai inferior. Hal itu dikarenakan EGD seringkali dinilai hanya ‘melengkapi' desain interior ataupun arsitektur yang secara volume lebih tinggi dibangingkan EGD, namun hal itu bukan berarti EGD merupakan sebuah obyek desain yang remeh. Tulisan ini akan membahas EGD dari Umeda Hospital yang didesain oleh Kenya Hara. Kajian terhadap desain tersebut dilakukan dengan melihatnya sebagai obyek desain grafis: memiliki elemen gambar dan tulisan. Dengan melihat relasi antara kedua elemen tersebut dalam EGD Umeda Hospital, penulis mendapatkan kesimpulan bagaimana EGD tersebut dirancang tidak hanya fungsional semata, namun juga konseptual dan juga memiliki pertimbangan estetik yang tidak kalah penting. Penulis berharap tulisan ini dapat menunjukkan otoritas dan mungkin kompleksitas dari disiplin desain grafis dalam perancangan EGD yang tidak kalah dengan disiplin ilmu lainnya

Singular limit of Hele-Shaw flow and dispersive regularization of shock waves

We study a family of solutions to the Saffman-Taylor problem with zero surface tension at a critical regime. In this regime, the interface develops a thin singular finger. The flow of an isolated finger is given by the Whitham equations for the KdV integrable hierarchy. We show that the flow describing bubble break-off is identical to the Gurevich-Pitaevsky solution for regularization of shock waves in dispersive media. The method provides a scheme for the continuation of the flow through singularites.Comment: Some typos corrected, added journal referenc

Viscous fingering and a shape of an electronic droplet in the Quantum Hall regime

We show that the semiclassical dynamics of an electronic droplet confined in the plane in a quantizing inhomogeneous magnetic field in the regime when the electrostatic interaction is negligible is similar to viscous (Saffman-Taylor) fingering on the interface between two fluids with different viscosities confined in a Hele-Shaw cell. Both phenomena are described by the same equations with scales differing by a factor of up to $10^{-9}$. We also report the quasiclassical wave function of the droplet in an inhomogeneous magnetic field.Comment: 4 pages, 1 eps figure include

The endowment effect and beliefs about the market

The endowment effect occurs when people assign a higher value to an item they own than to the same item when they do not own it, and this effect is often taken to reflect an ownership-induced change in the intrinsic value people assign to the object. However recent evidence shows that valuations made by buyers and sellers are influenced by market prices provided for the individual products, suggesting a role for beliefs about the markets. Here we elicit individuals’ beliefs about whole distributions of market prices, enabling us to quantify whether or not a given transaction constitutes a “good deal” and to demonstrate how an endowment effect may reflect such considerations. In a meta-analysis and three laboratory experiments, we show for the first time that ownership has no effect on beliefs about either: (a) the quality of the item or (b) the appropriate market price for the item. Instead, we show that sellers demand a price for the item that matches their beliefs about the item’s relative quality and the distribution of market prices in the market. Buyers, in contrast, offer less than what they believe the appropriate market price is. Thus, we argue that the endowment effect may largely reflect “adaptively rational” behavior on the part of both buyers and sellers (given their beliefs about relevant markets) rather than any ownership-induced bias or change in intrinsic preferences

Inflammatory Biomarkers in Childhood Arterial Ischemic Stroke: Correlates of Stroke Cause and Recurrence.

Background and purposeAmong children with arterial ischemic stroke (AIS), those with arteriopathy have the highest recurrence risk. We hypothesized that arteriopathy progression is an inflammatory process and that inflammatory biomarkers would predict recurrent AIS.MethodsIn an international study of childhood AIS, we selected cases classified into 1 of the 3 most common childhood AIS causes: definite arteriopathic (n=103), cardioembolic (n=55), or idiopathic (n=78). We measured serum concentrations of high-sensitivity C-reactive protein, serum amyloid A, myeloperoxidase, and tumor necrosis factor-α. We used linear regression to compare analyte concentrations across the subtypes and Cox proportional hazards models to determine predictors of recurrent AIS.ResultsMedian age at index stroke was 8.2 years (interquartile range, 3.6-14.3); serum samples were collected at median 5.5 days post stroke (interquartile range, 3-10 days). In adjusted models (including age, infarct volume, and time to sample collection) with idiopathic as the reference, the cardioembolic (but not arteriopathic) group had higher concentrations of high-sensitivity C-reactive protein and myeloperoxidase, whereas both cardioembolic and arteriopathic groups had higher serum amyloid A. In the arteriopathic (but not cardioembolic) group, higher high-sensitivity C-reactive protein and serum amyloid A predicted recurrent AIS. Children with progressive arteriopathies on follow-up imaging had higher recurrence rates, and a trend toward higher high-sensitivity C-reactive protein and serum amyloid A, compared with children with stable or improved arteriopathies.ConclusionsAmong children with AIS, specific inflammatory biomarkers correlate with cause and-in the arteriopathy group-risk of stroke recurrence. Interventions targeting inflammation should be considered for pediatric secondary stroke prevention trials