The Effects of Headcut and Knickpoint Propagation on Bridges in Iowa, October 2008

Headcuts (known also as primary knickpoints) and knickpoints (known also as secondary knickpoints) have been found to contribute to the accelerated riverbed degradation problem in the midwestern United States. Step-changes that occur at the head of channel networks are referred to as headcuts, and those that occur within the confines of channel banks are referred to as knickpoints. The formation of headcuts and knickpoints and their upstream migration have been linked to the over-steepening of stream reaches when the flow plunges to the bed and creates a plunge pool. Secondary flow currents and seepage are believed to be some other parameters contributing to the formation and evolution of headcuts and knickpoints. Ongoing research suggests that headcuts and knickpoints, where they form and migrate, may account for 60% (or more) of the bed erosion in the streams. Based on preliminary observations, there is a strong indication that headcuts and knickpoints can also have a greater influence on flow thalweg alignment (line of deepest flow) for small rivers. A shift in thalweg toward a riverbank or embankment is usually a prime factor contributing to riverbank erosion and scour.

Taking "Galton's problem" Seriously : Towards a Theory of Policy Diffusion

This article builds on the recent policy diffusion literature and attempts to overcome one of its major problems, namely the lack of a coherent theoretical framework. The literature defines policy diffusion as a process where policy choices are interdependent, and identifies several diffusion mechanisms that specify the link between the policy choices of the various actors. As these mechanisms are grounded in different theories, theoretical accounts of diffusion currently have little internal coherence. In this article we put forward an expected-utility model of policy change that is able to subsume all the diffusion mechanisms. We argue that the expected utility of a policy depends on both its effectiveness and the payoffs it yields, and we show that the various diffusion mechanisms operate by altering these two parameters. Each mechanism affects one of the two parameters, and does so in distinct ways. To account for aggregate patterns of diffusion, we embed our model in a simple threshold model of diffusion. Given the high complexity of the process that results, strong analytical conclusions on aggregate patterns cannot be drawn without more extensive analysis which is beyond the scope of this article. However, preliminary considerations indicate that a wide range of diffusion processes may exist and that convergence is only one possible outcome.

Molecular determinants of desensitization in an ENaC/degenerin channel.

Epithelial Na(+) channel (ENaC)/degenerin family members are involved in mechanosensation, blood pressure control, pain sensation, and the expression of fear. Several of these channel types display a form of desensitization that allows the channel to limit Na(+) influx during prolonged stimulation. We used site-directed mutagenesis and chemical modification, functional analysis, and molecular dynamics simulations to investigate the role of the lower palm domain of the acid-sensing ion channel 1, a member of the ENaC/degenerin family. The lower palm domains of this trimeric channel are arranged around a central vestibule, at ∼20 Å above the plasma membrane and are covalently linked to the transmembrane channel parts. We show that the lower palm domains approach one another during desensitization. Residues in the palm co-determine the pH dependence of desensitization, its kinetics, and the stability of the desensitized state. Mutations of palm residues impair desensitization by preventing the closing movement of the palm. Overexpression of desensitization-impaired channel mutants in central neurons allowed--in contrast to overexpression of wild type--a sustained signaling response to rapid pH fluctuations. We identify and describe here the function of an important regulatory domain that most likely has a conserved role in ENaC/degenerin channels.

Minimum requirements for application of ink dating methods based on solvent analysis in casework

Several ink dating methods based on solvents analysis using gas chromatography/mass spectrometry (GC/MS) were proposed in the last decades. These methods follow the drying of solvents from ballpoint pen inks on paper and seem very promising. However, several questions arose over the last few years among questioned documents examiners regarding the transparency and reproducibility of the proposed techniques. These questions should be carefully studied for accurate and ethical application of this methodology in casework. Inspired by a real investigation involving ink dating, the present paper discusses this particular issue throughout four main topics: aging processes, dating methods, validation procedures and data interpretation. This work presents a wide picture of the ink dating field, warns about potential shortcomings and also proposes some solutions to avoid reporting errors in court.

Aislamiento, identificación, clonación y análisis filogénico de la microalga Prorocentrum minimum (PAVILLARD) J. Schiller 1933 Aislada de la Bahía del Callao - Perú

Las Floraciones Algales Nocivas (FAN) o Mareas Rojas son decoloraciones del agua visible a simple vista debido a la proliferación de uno o más microorganismos planctónicos como las microalgas, estas pueden alcanzar niveles altos y producir efectos adversos a la salud humana, como también, causar daños a otros organismos marinos cercanos a la costa. Por tal motivo, existió el interés de aislar, identificar y hacer un estudio filogenético de la especie Prorocentrum minimum encontrada en la Bahía del Callao- Perú. Se realizaron varias tomas de muestras de agua de mar para su posterior identificación morfológica, se les efectuó la técnica de purificación de la microalga, y a su vez, se adquirió un estándar de Prorocentrum minimum del Instituto Provasoli- Guillard National Center for Culture of Marine Phytoplankton (CCMP), USA. Se realizó la curva de crecimiento para la concentración de la densidad microalgal, posteriormente se efectuó la extracción de ADN y la filogenia molecular a partir de las secuencias de las subunidades del ribosoma LSU rRNA de la especie Prorocentrum minimum. Se identificó P. minimum y P gracile, que fueron especies epibentónicos cercanas por ser más recientes evolutivamente. Para la confirmación de la presencia ausencia de alguna biotoxina marina en el cultivo de Prorocentrun minimum, se estableció un análisis cuantitativo de la dosis respuesta del animal en el bioensayo en ratón. Se logró obtener la purificación de cultivo de Prorocentrum minimum y estandarizar el protocolo de trabajo, se confirmó la filogenia de la especie de microalgas. No se logró obtener la toxina DSP del cultivo de la microalga.

The 19th Ion Channel Meeting. September 2008, France.

The annual meeting of the French Ion Channels Society, held on the Mediterranean coast of France, is aimed at gathering the international scientific community working on various aspects of ion channels. In this report of the 19th edition of the meeting, held in September 2008, we summarize selected symposia on aspects of the ion channel field from fundamental to clinical research. The meeting is an opportunity for leading investigators as well as young researchers to present and discuss their recent advances and future challenges in the ion channel field.

Iowa Fisheries Research Technical Series No. 75-1 Variations in the abundance of channel catfish year classes in the upper Mississippi River and causative factors Don R. Helms, Fishery Research Biologist Fisheries Section Jerry M. Conley, Superintendent of Fisheries December, 1975

study of channel catfish in the Mississippi River to determine differences in year class abundance and causative factors

Experimental conversion of colony social organization in fire ants (Solenopsis invicta): worker genotype manipulation in absence of queen effects

Colony social organization in the fire ant Solenopsis invicta appears to be under strong genetic control. In the invasive USA range, polygyny (multiple queens per colony) is marked by the presence of the Gp-9(b) allele in most of a colony's workers, whereas monogyny (single queen per colony) is associated with the exclusive occurrence of the Gp-9(B) allele. Ross and Keller, Behav Ecol Sociobiol 51:287-295 (2002) experimentally manipulated social organization by cross-fostering queens into colonies of the alternate form, thereby changing adult worker Gp-9 genotype frequencies over time. Although these authors showed that social behavior switched predictably when the frequency of b-bearing adult workers crossed a threshold of 5-10%, the possibility that queen effects caused the conversions could not be excluded entirely. We addressed this problem by fostering polygyne brood into queenright monogyne colonies. All such treatment colonies switched social organization to become polygyne, coincident with their proportions of b-bearing workers exceeding 12%. Our results support the conclusion that polygyny in S. invicta is induced by a minimum frequency of colony workers carrying the b allele, and further confirm that its expression is independent of queen genotype or history, worker genotypes at genes not linked to Gp-9, and colony genetic diversity.

Dispersal probability distributions and the wave-front speed problem

The speed and width of front solutions to reaction-dispersal models are analyzed both analytically and numerically. We perform our analysis for Laplace and Gaussian distribution kernels, both for delayed and nondelayed models. The results are discussed in terms of the characteristic parameters of the models

Zum Problem der Übersetzung von Gedichten : auch vom Gesichtspunkt des Computers

Abstract

A novel dominant mutation of the Nav1.4 alpha-subunit domain I leading to sodium channel myotonia.

BACKGROUND: Mutations in SCN4A may lead to myotonia. METHODS: Presentation of a large family with myotonia, including molecular studies and patch clamp experiments using human embryonic kidney 293 cells expressing wild-type and mutated channels. RESULTS: In a large family with historic data on seven generations and a clear phenotype, including myotonia at movement onset, with worsening by cold temperature, pregnancy, mental stress, and especially after rest after intense physical activity, but without weakness, the phenotype was linked with the muscle sodium channel gene (SCN4A) locus, in which a novel p.I141V mutation was found. This modification is located within the first transmembrane segment of domain I of the Na(v)1.4 alpha subunit, a region where no mutation has been reported so far. Patch clamp experiments revealed a mutation-induced hyperpolarizing shift (-12.9 mV) of the voltage dependence of activation, leading to a significant increase (approximately twofold) of the window current amplitude. In addition, the mutation shifted the voltage dependence of slow inactivation by -8.7 mV and accelerated the entry to this state. CONCLUSIONS: We propose that the gain-of-function alteration in activation leads to the observed myotonic phenotype, whereas the enhanced slow inactivation may prevent depolarization-induced paralysis.

Note on the blocking flow shop problem

We present some results attained with different algorithms for the Fm|block|Cmax problem using as experimental data the well-known Taillard instances.