From Car Parking to Protein Adsorption: An Overview of Sequential Adsorption Processes

The adsorption or adhesion of large particles (proteins, colloids, cells, >...) at the liquid-solid interface plays an important role in many diverse applications. Despite the apparent complexity of the process, two features are particularly important: 1) the adsorption is often irreversible on experimental time scales and 2) the adsorption rate is limited by geometric blockage from previously adsorbed particles. A coarse-grained description that encompasses these two properties is provided by sequential adsorption models whose simplest example is the random sequential adsorption (RSA) process. In this article, we review the theoretical formalism and tools that allow the systematic study of kinetic and structural aspects of these sequential adsorption models. We also show how the reference RSA model may be generalized to account for a variety of experimental features including particle anisotropy, polydispersity, bulk diffusive transport, gravitational effects, surface-induced conformational and orientational change, desorption, and multilayer formation. In all cases, the significant theoretical results are presented and their accuracy (compared to computer simulation) and applicability (compared to experiment) are discussed.Comment: 51 pages, 18 Figures, to appear in a special volume entitled "Adhesion of Submicron Particles on Solid Surfaces" of Colloids and Surfaces A, guest-edited by V. Privman.to appear in a special volume entitle

Brain metastases in osteosarcoma: incidence, clinical and neuroradiological findings and management options.

Brain metastasis is uncommon in osteosarcoma, but this may be changing with prolonged patient survival in the modern chemotherapy era. We present 5 patients with brain metastases out of 39 with lung metastasis (13%) in a total of 87 osteosarcoma patients. The clinical manifestations of brain metastases were catastrophic: massive hemorrhage in 2 and status epilepticus in 3. Metastases were single or multiple, and some were osteoblastic. Surgical intervention in 2 cases resulted in dramatic, though transient, clinical improvement. We advocate periodic neuroradiology screening in osteosarcoma patients with lung metastases, for early detection of brain involvement

Random Fan-Out State Induced by Site-Random Interlayer Couplings

We study the low-temperature properties of a classical Heisenberg model with site-random interlayer couplings on the cubic lattice. This model is introduced as a simplified effective model of Sr(Fe$_{1-x}$Mn$_{x}$)O$_2$, which was recently synthesized. In this material, when $x=0.3$, $(\pi\pi\pi)$ and $(\pi\pi0)$ mixed ordering is observed by neutron diffraction measurements. By Monte Carlo simulations, we find an exotic bulk spin structure that explains the experimentally obtained results. We name this spin structure the "random fan-out state". The mean-field calculations provide an intuitive understanding of this phase being induced by the site-random interlayer couplings. Since Rietveld analysis assuming the random fan-out state agrees well with the neutron diffraction pattern of Sr(Fe$_{0.7}$Mn$_{0.3}$)O$_2$, we conclude that the random fan-out state is reasonable for the spin-ordering pattern of Sr(Fe$_{0.7}$Mn$_{0.3}$)O$_2$ at the low-temperature phase.Comment: 13 pages, 12 figure

Gifted and talented education: The English policy highway at a crossroads?

Copyright © 2013 by Sage Publications. This is the author's accepted manuscript. The final published article is available from the link below.In 1999, the British government launched an education program for gifted and talented pupils as part of its Excellence in Cities initiative (EiC) that was initially designed to raise the educational achievement of very able pupils in state-maintained secondary schools in inner-city areas. Although some activities targeting gifted children had already been initiated by various voluntary organizations over several previous decades, this was the first time that the topic of improved provision for these pupils had been placed firmly within the national agenda. This article provides the background to the English gifted and talented policy “highway” and an overview of what was expected of schools. How practitioners responded to the policy, their beliefs and attitudes toward identifying gifted and talented pupils, and the opportunities and challenges that arose along the way to the current crossroads are explored. The need to empower teachers to feel more confident in classroom provisions for gifted and talented pupils is identified along with the potentially pivotal role of action research and “pupil voice” in the process of continued professional development and support

Análise de associação por todo o genoma para identificar locos relacionados ao lucro líquido, à vida produtiva e ao escore de células somáticas na raça Jersey.

Foi realizada uma varredura por todo o genoma de animais da raça Jersey, nos EUA, utilizando marcadores do tipo SNP, visando identificar QTL associados ao lucro líquido, à vida produtiva e ao escore de células somáticas. Os dados usados neste estudo foram provenientes do Animal Improvement Programs Laboratory, USDA/EUA. Amostras de DNA coletadas de 2.380 animais da raça Jersey e as habilidades preditas de transmissão de 2.081 animais, publicadas em fevereiro/2009 (http://greenbook.usjersey.com/), foram utilizadas nas análises. Para a genotipagem dos SNPs foi usado o BovineSNP50 BeadChip da Illumina, com aproximadamente 54.000 SNPs. Todo SNP com call rate (<99%), em desequilíbrio de Hardy-Weinberg (teste exato p<0,01) e com frequência de um dos alelos menor do que 5% foram excluídos das análises finais (30.342 SNP usados). P-values corrigidos pelo teste de Bonferroni iguais a 0,01 foram usados. Para todas as características, SNP significativos foram encontrados em vários cromossomos, especialmente nos BTAs 3, 4, 5, 6, 10, 12, 23 e 25. Os resultados sugerem que as soluções para os efeitos dos marcadores nas avaliações genômicas podem identificar regiões cromossômicas que necessitem ser melhor estudadas

Field-induced evolution of magnetic ordering in the quantum spin system (CuBr)Sr₂Nb₃O₁₀ with a ⅓ magnetization plateau

The field-induced evolution of the magnetic ordering in (CuBr)Sr₂Nb₃O₁₀ with a 1/3 magnetization plateau has been investigated by neutron diffraction under magnetic fields up to 10 T. With an increasing magnetic field, the zero-field helical antiferromagnetic (AFM) phase, AF1, with κ = [0 3/8 1/2] is replaced by a simple ferromagnetic phase with κ = [0 0 0], the formation of which is, however, retarded by the appearance of a second AFM, AF2, with κ = [0 1/3 &#8764;0.46]. Upon further increasing of the magnetic field, the AF2 phase disappears and only the ferromagnetic phase persists. The results clearly show that the magnetization plateau, induced by the competition between field-induced ferromagnetic, F, and AF2 phases, is coincidentally situated at M = 1/3 MS of the dc magnetization curve. The AF1 and AF2 phases have strongly differing magnetic propagation vectors and are therefore not directly related

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

Zebuines kerngenom und taurine Mitochondrien: admixtur von Nelore, der größten brasilianischen rinderrasse.

The beef industry is a major employment industry in Brazil and the country is currently the world’s third largest exporter of beef. From the mid-1950s to the mid-1960s, thousands of zebus were imported from India, establishing the meat breed Nelore (or Nellore). This study uses cluster analysis methods, implemented by the “admixture” software, to analyze the proportion of indicine and taurine genetic material in the current Nelore population. angus, Fleckvieh, Hereford, Holstein Friesian, Limousin and Piedmontese cattle breeds are used as taurine references. ancestral Nelore and Gir animals and the Brahman cattle breed serve as the indicine references