bluuebunny/crossref_metadata_2025 huggingface dataset:
Image-guided focused ultrasound ablation of breast cancer: current status, challenges, and future directions
Authors: Schmitz A. C. , Gianfelice D. , Daniel B. L. , Mali W. P. Th. M. , van den Bosch M. A. A. J.
Published: March 2008

Image-guided focussed ultrasound (FUS) ablation is a non-invasive procedure that has been used for treatment of benign or malignant breast tumours. Image-guidance during ablation is achieved either by using real-time ultrasound (US) or magnetic resonance imaging (MRI). The past decade phase I studies have proven MRI-guided and US-guided FUS ablation of breast cancer to be technically feasible and safe. We provide an overview of studies assessing the efficacy of FUS for breast tumour ablation as measured by percentages of complete tumour necrosis. Successful ablation ranged from 20% to 100%, depending on FUS system type, imaging technique, ablation protocol, and patient selection. Specific issues related to FUS ablation of breast cancer, such as increased treatment time for larger tumours, size of ablation margins, methods used for margin assessment and residual tumour detection after FUS ablation, and impact of FUS ablation on sentinel node procedure are presented. Finally, potential future applications of FUS for breast cancer treatment such as FUS-induced anti-tumour immune response, FUS-mediated gene transfer, and enhanced drug delivery are discussed. Currently, breast-conserving surgery remains the gold standard for breast cancer treatment.
Biomarkers of endothelial dysfunction are elevated and related to prognosis in chronic heart failure patients with diabetes but not in those without diabetes
Authors: Kistorp Caroline , Chong Aun Y. , Gustafsson Finn , Galatius Søren , Raymond Ilan , Faber Jens , Lip Gregory Y.H. , Hildebrandt Per
Published: March 2008

Background:

Biomarkers of endothelial dysfunction, such as soluble E‐selectin, and von Willebrand factor (vWf) are elevated in patients with chronic heart failure (CHF). The impact of diabetes mellitus (DM) on these biomarkers, and their relation to prognosis remains unknown.

Aims:

to investigate the impact of DM on plasma levels and the prognostic value of E‐selectin and vWf in patients with CHF.

Methods and results:

Plasma levels of E‐selectin and vWf were measured in 195 CHF patients with (n = 48, 24.5%), and without DM, and in 116 age‐matched healthy controls. Compared with controls, median plasma E‐selectin levels were higher in CHF patients with DM (P = 0.012), but not in CHF patients without DM (P = 0.45); vWf levels were also higher in CHF patients with DM (P < 0.001), but not without DM (P = 0.108). E‐selectin was associated with risk of recurrent ischaemic cardiovascular events among CHF patients with DM (HR 2.60; P = 0.009), but not among patients without DM (HR 1.09; P = 0.60) per 1 SD increment in log transformed variable. vWf was not related with outcome in CHF patients with or without DM.

Conclusions:

Plasma levels of E‐selectin and vWf are elevated in CHF patients with DM but not in those without DM. High E‐selectin levels may be associated with ischaemic events in patients with DM.
Synchronous early‐stage endometrial and ovarian cancer
Authors: Signorelli Mauro , Fruscio Robert , Lissoni Andrea Alberto , Pirovano Cecilia , Perego Patrizia , Mangioni Costantino
Published: March 2008

Objective

To explore the clinicopathologic findings and oncological outcome of early‐stage synchronous endometrial and ovarian malignancies.

Methods

A retrospective study of 93 women with synchronous stage I ovarian and stage I–II endometrial cancer treated between December 1981 and August 2005 in the gynecologic oncology department of San Gerardo Hospital, Italy.

Results

Fifty‐one percent of the ovarian tumors were stage Ia and 71% of the endometrial cancers had minimal myometrial invasion. Endometrioid histology and grade 2 disease were prevalent in both sites. Hyperplasia and endometriosis coexisted in 71% and 22% of endometrial and ovarian cancers, respectively. The actuarial 5‐year disease‐free and overall survival rates were 83% and 96%, respectively.

Conclusion

The incidence of synchronous endometrial and ovarian cancer is not negligible, especially among young women. Synchronous cancers show very favorable pathologic features and have an excellent oncologic outcome. Adjuvant therapy should be tailored according to surgical staging and histology.
Environmental Chauvinism in the Prussian East: Forestry as a Civilizing Mission on the Ethnic Frontier, 1871–1914
Authors: Wilson Jeffrey K.
Published: March 2008

The Tuchel Heath (Tucheler Heide, Bóry Tucholskie) and Kashubia (Kassubei, Kaszuby), the two regions comprising the geographical region known as Pomerelia (roughly the area of the “Polish Corridor”), came into Prussian possession with annexations from Poland in 1772, when Friedrich II seized most of what would become the provinces of Poznania and West Prussia from the ailing Polish Republic. These territories, some liked to imagine, resembled the North American frontier. Friedrich II apparently compared it to Canada and “jokingly named the inhabitants his Iroquois.” Gustav Freytag immortalized Friedrich's arrival on the frontier in his workBilder aus der deutschen Vergangenheit, characterizing the place as “an abandoned land, without law, without authority; it was a wasteland.” Certainly, the harsh climate, the sprawling pine forests and barrens, and the impoverished populace suggested a certain affinity. In one description of the region from 1879, the author depicted the Slavic game poacher “as a red Indian on the warpath.”
Inviscid coupling between point symmetric bodies and singular distributions of vorticity
Authors: EAMES I. , LANDERYOU M. , FLÓR J. B.
Published: March 2008

We study the inviscid coupled motion of a rigid body (of density ρb, in a fluid of density ρ) and singular distributions of vorticity in the absence of gravity, using for illustration a cylinder moving near a point vortex or dipolar vortex, and the axisymmetric interaction between a vortex ring and sphere.

The coupled motion of a cylinder (radius a) and a point vortex, initially separated by a distance R and with zero total momentum, is governed by the parameter R4/(ρb/ρ+1)a4. When R4/(ρb/ρ+1)a4,≤,1, a (positive) point vortex moves anticlockwise around the cylinder which executes an oscillatory clockwise motion, with a mixture of two frequencies, centred around its initial position. When R4/(ρb/ρ+1)a4≫1, the initial velocity of the cylinder is sufficiently large that the dynamics become uncoupled, with the cylinder moving off to infinity. The final velocity of the cylinder is related to the permanent displacement of the point vortex.

The interaction between a cylinder (initially at rest) and a dipolar vortex starting at infinity depends on the distance of the vortex from the centreline (h), the initial separation of the vortical elements (2d), and ρb/ρ. For a symmetric encounter (h=0) with a dense cylinder, the vortical elements pass around the cylinder and move off to infinity, with the cylinder being displaced a finite distance forward. However, when ρb/ρ<1, the cylinder is accelerated forward to such an extent that the vortex cannot overtake. Instead, the cylinder ‘extracts’ a proportion of the impulse from the dipolar vortex. An asymmetric interaction (h>0) leads to the cylinder moving off in the opposite direction to the dipolar vortex.

To illustrate the difference between two- and three-dimensional flows, we consider the axisymmetric interaction between a vortex ring and a rigid sphere. The velocity perturbation decays so rapidly with distance that the interaction between the sphere and vortex ring is localized, but the underlying processes are similar to two-dimensional flows.

We briefly discuss the general implications of these results for turbulent multiphase flows.
Velocity and temperature derivatives in high-Reynolds-number turbulent flows in the atmospheric surface layer. Part 1. Facilities, methods and some general results
Authors: GULITSKI G. , KHOLMYANSKY M. , KINZELBACH W. , LÜTHI B. , TSINOBER A. , YORISH S.
Published: March 2008

This is a report on a field experiment in an atmospheric surface layer at heights between 0.8 and 10m with the Taylor micro-scale Reynolds number in the rangeReλ = 1.6−6.6 ×103. Explicit information is obtained on the full set of velocity and temperature derivatives both spatial and temporal, i.e. no use of Taylor hypothesis is made. The report consists of three parts. Part 1 is devoted to the description of facilities, methods and some general results. Certain results are similar to those reported before and give us confidence in both old and new data, since this is the first repetition of this kind of experiment at better data quality. Other results were not obtained before, the typical example being the so-called tear-dropR-Qplot and several others. Part 2 concerns accelerations and related matters. Part 3 is devoted to issues concerning temperature, with the emphasis on joint statistics of temperature and velocity derivatives. The results obtained in this work are similar to those obtained in experiments in laboratory turbulent grid flow and in direct numerical simulations of Navier–Stokes equations at much smaller Reynolds numbersReλ ~ 102, and this similarity is not only qualitative, but to a large extent quantitative. This is true of such basic processes as enstrophy and strain production, geometrical statistics, the role of concentrated vorticity and strain, reduction of nonlinearity and non-local effects. The present experiments went far beyond the previous ones in two main respects. (i) All the data were obtained without invoking the Taylor hypothesis, and therefore a variety of results on fluid particle accelerations became possible. (ii) Simultaneous measurements of temperature and its gradients with the emphasis on joint statistics of temperature and velocity derivatives. These are reported in Parts 2 and 3.
Effect of gravity modulation on the stability of a horizontal double-diffusive layer
Authors: YU YOUMIN , CHAN CHO LIK , CHEN C. F.
Published: March 2008

The instability characteristics of a horizontal stably stratified fluid layer being heated from below, including its subsequent nonlinear evolution under steady and modulated gravity, have been investigated by experiments and two-dimensional numerical simulations. The critical condition at instability onset is also checked using linear stability analysis. The fluid is contained in a horizontal test tank with an initial stable solute gradient and a constant-temperature gradient imposed by heating from below. Because of the non-diffusive boundaries, the vertical solute gradient slowly decreases and, eventually, the layer becomes unstable. From the time of the onset of instability, the critical solute Rayleigh number is determined. For the experiments with modulated gravity, the tank is fixed onto a platform that oscillates vertically at 1 Hz with an amplitude of 10 cm. The experiment is designed such that no internal wave mode of instability can be excited. The experimental results show that gravity modulation destabilizes the system slightly by increasing the solute Rayleigh number at onset by 8.4% and causes the oscillation frequency at onset to increase by 32.6%. Linear stability analysis and two-dimensional numerical simulations for the steady gravity case yield results that are in good agreement with the experiment. For the gravity modulation case, linear stability results do not show any effect of gravity modulation at the frequency of 1 Hz. Numerical simulation results do show increases in both the onset solute Rayleigh number and the oscillation frequency; however, their values are smaller than those obtained in the experiment. The characteristics of the internal wave mode of instability are explored by numerical simulations of a stably stratified solute fluid layer under gravity modulation. The interference effects between the internal wave mode and double-diffusive mode of instabilities are studied by imposing an adverse temperature gradient on the stratified layer.
Geometry of unsteady fluid transport during fluid–structure interactions
Authors: FRANCO ELISA , PEKAREK DAVID N. , PENG JIFENG , DABIRI JOHN O.
Published: March 2008

We describe the application of tools from dynamical systems to define and quantify the unsteady fluid transport that occurs during fluid–structure interactions and in unsteady recirculating flows. The properties of Lagrangian coherent structures (LCS) are used to enable analysis of flows with arbitrary time-dependence, thereby extending previous analytical results for steady and time-periodic flows. The LCS kinematics are used to formulate a unique, physically motivated definition for fluid exchange surfaces and transport lobes in the flow. The methods are applied to numerical simulations of two-dimensional flow past a circular cylinder at a Reynolds number of 200; and to measurements of a freely swimming organism, the Aurelia aurita jellyfish. The former flow provides a canonical system in which to compare the present geometrical analysis with classical, Eulerian (e.g. vortex shedding) perspectives of fluid–structure interactions. The latter flow is used to deduce the physical coupling that exists between mass and momentum transport during self-propulsion. In both cases, the present methods reveal a well-defined, unsteady recirculation zone that is not apparent in the corresponding velocity or vorticity fields. Transport rates between the ambient flow and the recirculation zone are computed for both flows. Comparison of fluid transport geometry for the cylinder crossflow and the self-propelled swimmer within the context of existing theory for two-dimensional lobe dynamics enables qualitative localization of flow three-dimensionality based on the planar measurements. Benefits and limitations of the implemented methods are discussed, and some potential applications for flow control, unsteady propulsion, and biological fluid dynamics are proposed.
Structure of turbulent flow over regular arrays of cubical roughness
Authors: COCEAL O. , DOBRE A. , THOMAS T. G. , BELCHER S. E.
Published: March 2008

The structure of turbulent flow over large roughness consisting of regular arrays of cubical obstacles is investigated numerically under constant pressure gradient conditions. Results are analysed in terms of first- and second-order statistics, by visualization of instantaneous flow fields and by conditional averaging. The accuracy of the simulations is established by detailed comparisons of first- and second-order statistics with wind-tunnel measurements. Coherent structures in the log region are investigated. Structure angles are computed from two-point correlations, and quadrant analysis is performed to determine the relative importance of Q2 and Q4 events (ejections and sweeps) as a function of height above the roughness. Flow visualization shows the existence of low-momentum regions (LMRs) as well as vortical structures throughout the log layer. Filtering techniques are used to reveal instantaneous examples of the association of the vortices with the LMRs, and linear stochastic estimation and conditional averaging are employed to deduce their statistical properties. The conditional averaging results reveal the presence of LMRs and regions of Q2 and Q4 events that appear to be associated with hairpin-like vortices, but a quantitative correspondence between the sizes of the vortices and those of the LMRs is difficult to establish; a simple estimate of the ratio of the vortex width to the LMR width gives a value that is several times larger than the corresponding ratio over smooth walls. The shape and inclination of the vortices and their spatial organization are compared to recent findings over smooth walls. Characteristic length scales are shown to scale linearly with height in the log region. Whilst there are striking qualitative similarities with smooth walls, there are also important differences in detail regarding: (i) structure angles and sizes and their dependence on distance from the rough surface; (ii) the flow structure close to the roughness; (iii) the roles of inflows into and outflows from cavities within the roughness; (iv) larger vortices on the rough wall compared to the smooth wall; (v) the effect of the different generation mechanism at the wall in setting the scales of structures.
Energy and enstrophy fluxes in the double cascade of two-dimensional turbulence
Authors: BOFFETTA G.
Published: March 2008

High-resolution direct numerical simulations of two-dimensional turbulence in stationary conditions are presented. The development of an energy–enstrophy double cascade is investigated and its statistics found to be compatible with the classical Kraichnan theory in the limit of extended inertial ranges. The analysis of the joint distribution of energy and enstrophy fluxes in physical space reveals a small value of cross-correlation. This result supports many experimental and numerical studies where only one cascade is generated.
A dissipative point-vortex model for nearshore circulation
Authors: TERRILE E. , BROCCHINI M.
Published: March 2008

The hydrodynamic circulation of a nearshore region with complex bathymetry is inves- tigated by means of a point-vortex approach similar, but more complete and suited to practical applications, to that of Kennedy (J. Fluid Mech. vol. 497, 2003, p. 225). The generation and dissipation of each single-point vortex are analysed in detail to obtain a complete description of the vortex dynamics. In particular, we clarify how the mechanism for the generation of breaking-wave-induced macrovortices (large-scale two-dimensional horizontal vortices) can be practically implemented and we discuss in detail the mechanism leading to the dissipation of the circulation assigned to each vortex. Available approximate relations for the rate of generation of bar vortices are placed in context and discussed in detail, and novel approximate relations for the shore vortex generation and for the vortex viscous dissipation are proposed, the latter largely improving the description of the point vortex dynamics. Results have been obtained using three ‘typical’ rip-current bathymetries for which we also test qualitatively and quantitatively the model comparing the vorticity dynamics with the results obtained by means of both wave-resolved and wave-averaged circulation models. A comparison of dynamically equivalent flow configurations shows that the dissipative point-vortex model solutions, neglecting any influence of the wave field, provide rip current velocities in good agreement with both types of numerical solution. A more complete description of the rip current system, not limited to the rip-neck region as given by Kennedy (2003) by mean of an inviscid model, has been achieved by including dissipative effects.
Gas flows in microchannels and microtubes
Authors: CAI CHUNPEI , SUN QUANHUA , BOYD IAIN D.
Published: March 2008

This study analyses compressible gas flows through microchannels or microtubes, and develops two complete sets of asymptotic solutions. It is a natural extension of the previous work by Arkilicet al. on compressible flows through microchannels. First, by comparing the magnitudes of different forces in the compressible gas flow, we obtain proper estimations for the Reynolds and Mach numbers at the outlets. Second, based on these estimations, we obtain asymptotic analytical solutions of velocities, pressure and temperature distributions of compressible gas flow inside the microchannels and microtubes with a relaxation of the isothermal assumption, which was previously used in many studies. Numerical simulations of compressible flows through a microchannel and a microtube are performed by solving the compressible Navier–Stokes equations, with velocity slip and temperature jump wall boundary conditions. The numerical simulation results validate the analytical results from this study.
Denjoy systems and dimension groups
Authors: MASUI KENICHI , SUGISAKI FUMIAKI , YOSHIDA MASAMICHI
Published: March 2008

We construct an adic model for the Denjoy system (X,T) of finite double orbit number. It is based on the dual Ostrowski numeration system. By using this construction, we can determine the K-theory of $C(X)\rtimes _T \mathbb {Z}$ associated with (X,T) in an effective way.
Square summability of variations and convergence of the transfer operator
Authors: JOHANSSON ANDERS , ÖBERG ANDERS
Published: March 2008

In this paper we study the one-sided shift operator on a state space defined by a finite alphabet. Using a scheme developed by Walters [P. Walters. Trans. Amer. Math. Soc.353(1) (2001), 327–347], we prove that the sequence of iterates of the transfer operator converges under square summability of variations of the g-function, a condition which gave uniqueness of a g-measure in our earlier work [A. Johansson and A. Öberg. Math. Res. Lett.10(5–6) (2003), 587–601]. We also prove uniqueness of the so-called G-measures, introduced by Brown and Dooley [G. Brown and A. H. Dooley. Ergod. Th. & Dynam. Sys.11 (1991), 279–307], under square summability of variations.
Autonomous vehicle based in cooperative GPS and inertial systems
Authors: Milanés Vicente , Naranjo José E. , González Carlos , Alonso Javier , de Pedro Teresa
Published: March 2008

A system including Global Positioning Systems (GPS) and digital cartography is a good solution to carry out vehicle's guidance. However, it has inconveniences like high sensibility to multipath and interference when the GPS signal is blocked by external agents. Another system is mandatory to avoid this error. This paper presents a cooperative system based on GPS and Inertial Navigation Systems (INS) for automated vehicle position. The control system includes a decision unit to choose which value is the correct. In case GPS is working at top precision, it takes the control. On the other part, GPS signal can be lost and inertial control system guides the car in this occasion. A third possibility is contemplated: we receive the signal from GPS but the accuracy is over one meter. Now, position value is obtained by means of both systems. Experimental results analyze two situations: guidance in an urban area where GPS signal can be occluded by buildings or trees during short time intervals and the possibility of loss of the signal in long time to simulate the circulation in tunnels. Good results have been observed in tests and it demonstrates how a cooperative system improves the automated vehicle guidance.
DISCRETE SCATTERING AND SIMPLE AND NONSIMPLE FACE-HOMOGENEOUS RANDOM WALKS
Authors: Hordijk Arie , Popov Nikolay , Spieksma Flora
Published: March 2008

In this article we will derive some results for characterizing the almost closed sets of a face-homogeneous random walk. We will present a conjecture on the relation between discrete scattering of the fluid limit and the absence of nonatomic almost closed sets. We will illustrate the conjecture with random walks with both simple and nonsimple decomposition into almost closed sets.
INSURANCE RISK WITH VARIABLE NUMBER OF POLICIES
Authors: Adan Ivo , Kulkarni Vidyadhar
Published: March 2008

In this article we consider an insurance company selling life insurance policies. New policies are sold at random points in time, and each policy stays active for an exponential amount of time with rate μ, during which the policyholder pays premiums continuously at rate r. When the policy expires, the insurance company pays a claim of random size. The aim is to compute the probability of eventual ruin starting with a given number of policies and a given level of insurance fund. We establish the remarkable result that the ruin probability is identical to the one in the standard compound Poisson model where the insurance fund increases at constant rate r and claims occur according to a Poisson process with rate μ.
ASYMPTOTIC PROPERTIES OF SOJOURN TIMES IN MULTICLASS TIME-SHARED SYSTEMS
Authors: Kherani Arzad A.
Published: March 2008

We consider two multiclass discriminatory process sharing (DPS)-like time-shared M/G/1 queuing systems in which the weight assigned to a customer is a function of its class as well as (1) the attained service of the customer in the first system and (2) the residual processing time of the customer in the second system. We study the asymptotic slowdown, the ratio of expected sojourn time to the service requirement, of customers with very large service requirements. We also provide various results dealing with ordering of conditional mean sojourn times of any two given classes. We also show that the sojourn time of an arbitrary customer of a particular class in the standard DPS system (static weights) with heavy-tailed service requirements has a tail behavior similar to that of a customer from the same class that starts a busy period.
INSENSITIVITY OF A FRONT-END WEB SYSTEM
Authors: Yamazaki Genji , Sogo Tamotsu
Published: March 2008

In many companies, legacy systems have been used to serve customers arriving at service counters. The demand of a customer arriving at a counter is divided into R subdemands (SDs). Each SD is processed sequentially by the legacy system. When the final SD service is completed, the customer leaves the counter. On the other hand, Internet users desire that each SD be processed through the Internet without going to a service counter. We note that the applications for operating the web system differ from those of the legacy systems. For that reason, companies might use legacy systems for customers who come to the company through the Internet, without changing those legacy systems' applications. This web system, which is integrated with the legacy system, is called a front-end web system. Suppose that, for the web system, demands are generated according to a Poisson process. Then we show that the loss probability and macrostate distribution for the front-end web system are insensitive with respect to the distribution of the discrete random variable R, aside from the continuous distributions of other uncertain factors, under a restriction.
TP2 DEPENDENCE OF SAMPLE SPACINGS WITH APPLICATIONS
Authors: Li Xiaohu , Hu Xiaoxiao , Li Zhouping
Published: March 2008

This article investigates TP2 dependence of sample spacings. It is proved that TP2 (RR2) dependence between a general spacing and a nonadjacent order statistic might be characterized by the DLR (ILR) property of the parent distribution, and TP2 dependence between any pair of consecutive spacings might be characterized by the DLR aging property of the population. Furthermore, TP2 dependence between any two consecutive spacings in multiple outliers exponential models is also derived. In addition, some applications in reliability and business auction are presented as well.
Die quantitative Messung der Echogenität des Nierenparenchyms
Authors: Tuma J. , Schwarzenbach H.-R. , Nováková B. , Jungius K.-P. , Kuchta M.
Published: March 2008

Die qualitative Beurteilung der Echogenität der Nierenrinde und der Markpyramiden gehört zu den wichtigsten diagnostischen Kriterien bei der Beurteilung der diffusen Nierenparenchymerkrankungen. Es ist von Interesse, diese Beurteilung durch quantitative Angaben zu ergänzen. Die Echogenität der Rinde und des Markes wurde in digitalisierten Bildern quantitativ beurteilt. Die Präzision der wiederholten Messungen betrug 0.83% und die Präzision der wiederholten Messung durch zwei Untersucher 2.03%. Der Einfluss von Furosemid auf die Echogenität des Nierenparenchyms wurde bei vier gesunden Erwachsenen untersucht. Die Echogenität der Nierenrinde ist nach 3 resp. 6 Minuten signifikant angestiegen, während die Echogenität des Nierenmarkes unverändert blieb. Unsere Untersuchung zeigt, dass eine präzise Messung der Echogenität im Nierenparenchym möglich ist. Unter dem Einfluss von Furosemid kommt es zu einem signifikanten Anstieg der Echogenität der Nierenrinde.
Protocole pour l´évaluation et la prise en charge des plaies chroniques
Authors: Genoud C. , Weller J.
Published: March 2008

Eine Umfrage unter Pflegenden, welche Patienten zu Hause betreuen, hat 2001 gezeigt, dass ein grosses Bedürfnis an Unterstützung bei der Pflege von chronischen Wunden besteht. In der Folge wurden ein Protokoll zur Beurteilung und Behandlung chronischer Wunden ausgearbeitet und eine Gruppe von speziell ausgebildeten Pflegepersonen gebildet, die Ärzten, Pflegenden und Patienten für Fragen und Beratungen zur Verfügung stehen.
Das Arbeitsgedächtnis von 4- bis 5-jährigen Kindern
Authors: Schmid Corinne , Zoelch Christof , Roebers Claudia M.
Published: March 2008

Zusammenfassung. In der vorliegenden Arbeit werden Möglichkeiten und Grenzen der frühzeitigen, möglichst genauen und differenzierten Erfassung von Arbeitgedächtniskompetenzen bei Kindern untersucht. An einer Stichprobe von N = 84 4- bis 5-jährigen Kindern wurden acht verschiedene Aufgaben eingesetzt. Die eine Hälfte der Kinder wurde nach drei Wochen einer Wiederholungsmessung unterzogen, die andere Hälfte absolvierte zusätzlich Aufgaben zur Informationsverarbeitungsgeschwindigkeit und zu globaleren Maßen der kognitiven Leistungsfähigkeit. Die Ergebnisse deuten auf eine zuverlässige, spezifische Messung verschiedener Arbeitsgedächtnisprozesse hin: Die Leistungen der 4-Jährigen ließen sich von denen der 5-Jährigen statistisch abgrenzen, die Test-Retest-Reliabilitäten erwiesen sich als hoch und es ergaben sich differentielle Zusammenhangsmuster zu den externen Messinstrumenten. Die faktorenanalytischen Auswertungen erbrachten eine nicht unbedingt modellkonforme Struktur des Arbeitsgedächtnisses, die auf eine allmähliche Ausdifferenzierung der Teilprozesse mit zunehmendem Alter und zunehmendem Einsatz hindeuten könnte.
Simulated Solar Mass Ejection Imager and “Solar Terrestrial Relations Observatory‐like” views of the solar wind following the solar flares of 27–29 May 2003
Authors: Sun W. , Deehr C. S. , Dryer M. , Fry C. D. , Smith Z. K. , Akasofu S.‐I.
Published: March 2008

The three‐dimensional Hakamada‐Akasofu‐Fry (HAFv.2) kinematic solar wind model can be extended to predict what the Solar Terrestrial Relations Observatory (STEREO) spacecraft might expect in observing large‐scale plasma clouds ejected from the Sun. In order to demonstrate this capability, the HAFv.2 model was used to simulate the first observations of a halo coronal mass ejection (CME) from the Solar Mass Ejection Imager (SMEI) instrument on the Coriolis spacecraft, acquired after the solar events of 27–29 May 2003. Projections of the Thomson‐scattered white light intensity on the plane of sky, as observed by the SMEI cameras, were calculated from the three‐dimensional simulations. These simulations of the background solar wind and two shock fronts compare favorably with the white light observations of plasma clouds by the SMEI instrument. The method thus developed is then applied to hypothetical locations of the STEREO spacecraft in a later phase of the STEREO mission. It is shown that the model can be a valuable aid and guide in the identification of multiple shock‐induced variations of the solar wind.
Detecting micrometer‐scale platinum‐group minerals in mantle peridotite with microbeam synchrotron radiation X‐ray fluorescence analysis
Authors: Kogiso Tetsu , Suzuki Katsuhiko , Suzuki Toshihiro , Shinotsuka Kazunori , Uesugi Kentaro , Takeuchi Akihisa , Suzuki Yoshio
Published: March 2008

Platinum‐group elements (PGE) in the Earth's mantle are key tracers for understanding the differentiation history of the Earth. PGE in mantle peridotite are strongly concentrated in Fe‐Ni‐Cu sulfides, whereas platinum‐group minerals, rarely found in peridotite, are additional potential phases that host PGE in the mantle. However, the abundances of platinum‐group minerals are not well constrained because they are generally too small to be detected with conventional analytical tools. We employed microbeam synchrotron radiation X‐ray fluorescence to efficiently detect micrometer‐scale platinum‐group minerals in rock samples. This nondestructive technique allows location of micrometer‐scale minerals from the interior of rock thin sections. With this method, we detected micrometer‐scale platinum‐group minerals in an orogenic lherzolite sample. The platinum‐group minerals range from ∼1 μm to 10 μm in maximum dimension. They are located near or within Fe‐Ni‐Cu sulfides, which were not exposed on the thin section surface. Nine grains of platinum‐group minerals in total were detected in just one peridotite thin section, demonstrating the high efficiency of this method for detecting micrometer‐scale minerals from the inside of rock samples.
Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes
Authors: McGonigle A. J. S. , Aiuppa A. , Giudice G. , Tamburello G. , Hodson A. J. , Gurrieri S.
Published: March 2008

We report the first measurements of volcanic gases with an unmanned aerial vehicle (UAV). The data were collected at La Fossa crater, Vulcano, Italy, during April 2007, with a helicopter UAV of 3 kg payload, carrying an ultraviolet spectrometer for remotely sensing the SO2 flux (8.5 Mg d−1), and an infrared spectrometer, and electrochemical sensor assembly for measuring the plume CO2/SO2 ratio; by multiplying these data we compute a CO2 flux of 170 Mg d−1. Given the deeper exsolution of carbon dioxide from magma, and its lower solubility in hydrothermal systems, relative to SO2, the ability to remotely measure CO2 fluxes is significant, with promise to provide more profound geochemical insights, and earlier eruption forecasts, than possible with SO2 fluxes alone: the most ubiquitous current source of remotely sensed volcanic gas data.
Late Holocene climate oscillations and solar fluctuations from speleothem STAL‐AH‐1, Sauerland, Germany: A numerical perspective
Authors: Jackson A. S. , McDermott F. , Mangini A.
Published: March 2008

Initial 14C activity in a late Holocene stalagmite (a14Cstal) from Attahöhle (Sauerland, Germany) varies synchronously with atmospheric 14C activity (a14Catm). This observation provides independent chronological support for the correlation between a solar forcing proxy (atmospheric 14C production rate, a14Cprod) and a climate proxy (δ18Ostal) in this stalagmite, and eliminates the need to ‘tune’ the chronology. Monte Carlo randomizations in which 100,000 synthetic δ18Ostal datasets were generated indicate that the correlation between a14Cprod and δ18Ostal is statistically robust. The absence of a significant time lag between a14Cprod and δ18Ostal implies rapid climate response at this site to variations in solar output. Positively correlated a14Cprod‐δ18Ostal indicates drier winter conditions during late Holocene solar minima. This supports atmospheric amplification models that predict reduced NAO indices during solar minima if kinetic enrichment of δ18O during dry phases outweighs the reduction of δ18O in rainfall that results from lower air temperatures during negative NAO phases.
Vertical propagation of information in a middle atmosphere data assimilation system by gravity‐wave drag feedbacks
Authors: Ren Shuzhan , Polavarapu Saroja M. , Shepherd Theodore G.
Published: March 2008

The mesospheric response to the 2002 Antarctic Stratospheric Sudden Warming (SSW) is analysed using the Canadian Middle Atmosphere Model Data Assimilation System (CMAM‐DAS), where it represents a vertical propagation of information from the observations into the data‐free mesosphere. The CMAM‐DAS simulates a cooling in the lowest part of the mesosphere which is accomplished by resolved motions, but which is extended to the mid‐ to upper mesosphere by the response of the model's non‐orographic gravity‐wave drag parameterization to the change in zonal winds. The basic mechanism is that elucidated by Holton consisting of a net eastward wave‐drag anomaly in the mesosphere during the SSW, although in this case there is a net upwelling in the polar mesosphere. Since the zonal‐mean mesospheric response is shown to be predictable, this demonstrates that variations in the mesospheric state can be slaved to the lower atmosphere through gravity‐wave drag.
Decrease of sea ice thickness at Hopen, Barents Sea, during 1966–2007
Authors: Gerland S. , Renner A. H. H. , Godtliebsen F. , Divine D. , Løyning T. B.
Published: March 2008

Seasonal fast ice thickness at the island of Hopen (Barents Sea) was monitored over 40 years. Sea ice thickness variability as a climate indicator provides more quantitative information on the state of the ice cover than solely sea ice extent. Usually, starting to form just before December Hopen fast ice reaches maximum thickness in May (on average 0.99 m), before the ice starts to decay. Swell, currents, and winds interrupt the fast ice development at Hopen during several of the winters observed, leading to ice removal and new ice formation. Since 2000, no ice thicker than 1.0 m was observed. We find a trend in the ice thickness anomalies of −0.11 m per decade, coinciding with decreasing seasonal maximum ice thickness, and an increase in local surface air and water temperatures. This is consistent with the decreasing sea ice extent in the Barents Sea and the entire Arctic.
The horizontal hum of the Earth: A global background of spheroidal and toroidal modes
Authors: Kurrle Dieter , Widmer‐Schnidrig Rudolf
Published: March 2008

It is well known that the fundamental spheroidal modes of the Earth are continuously excited. The vertical motions of this ‘hum of the Earth’ can be observed at many stations all over the world. However, there exists no hum observation based on horizontal seismic data yet. In this article, we present observations of continuous horizontal background oscillations of the Earth at four exceptionally quiet seismic stations and show the existence of a so far unknown global background of long‐period Love waves and, equivalently, fundamental toroidal modes. Spheroidal and toroidal modes exhibit similar horizontal amplitudes which, for the spheroidal modes, agree with those expected from the vertical component data. Neither earthquakes nor spheroidal‐toroidal mode coupling can explain a permanent excitation of toroidal modes at this level.
Influence of large‐scale interplanetary structures on energetic particle propagation: September 2004 event at Ulysses and ACE
Authors: Lario D. , Decker R. B. , Malandraki O. E. , Lanzerotti L. J.
Published: March 2008

An intense solar energetic particle (SEP) event was detected in September 2004 by near‐Earth spacecraft and by Ulysses at 5.4 AU. Characteristics of the intensity and anisotropy time profiles at both heliospheric locations were determined by the presence of a corotating low‐density, low‐speed, and low‐proton‐beta βp solar wind stream. This low‐βp stream was followed by a faster and denser solar wind that formed a strong compression region. The bulk of energetic particles at 1 AU were observed downstream of this compression region. Only those particles either able to leak from behind the compression region, accelerated by the shock driven by the coronal mass ejection that generated the SEP event as it penetrated into the low‐βp region, or both were observed prior to the main component of the SEP event at 1 AU. Anisotropic ion intensity enhancements observed upstream of this shock resulted from both particle acceleration in a corrugated shock surface and particle propagation within the low‐βp region. The particle event at Ulysses had exceptionally large and long‐lasting (>4 days) field‐aligned anisotropies. These large anisotropies resulted from both leakage of energetic particles from behind the compression region and their propagation within the low‐βp region. We propose a scenario that explains the characteristics of the particle event at both 1 AU and Ulysses. The effects that large‐scale interplanetary structures have on the energetic particle transport determine the properties of the event at both spacecraft. These effects must be carefully considered by models of energetic particle transport in the heliosphere.
Secondary aerosols in Switzerland and northern Italy: Modeling and sensitivity studies for summer 2003
Authors: Andreani‐Aksoyoglu Sebnem , Keller Johannes , Prévôt Andre S. H. , Baltensperger Urs , Flemming Johannes
Published: March 2008

The formation and transport of secondary aerosols during a 4‐day period in summer 2003 were studied using the 3‐dimensional air quality model CAMx (Comprehensive Air quality Model with eXtensions) over an area covering regions north and south of the Swiss Alps with different air pollution characteristics. The modeled components were particulate sulfate, nitrate, ammonium, primary (POA) and secondary organic aerosols (SOA) and elemental carbon (EC) with a particle diameter smaller than 2.5 μm. Highest concentrations were predicted in northern Italy. The modeled sum of particle mass concentrations was in general lower than PM2.5 measurements most probably due to an underestimation of organic aerosols. Differences between the regions in the north and the south of the Alps are discussed with respect to the aerosol concentrations and to the sensitivity of aerosol formation. Sensitivity tests using reduced NH3 and NOx emissions suggest that in northern Switzerland secondary aerosol formation is unlikely to be limited by NH3 but rather by HNO3. On the other hand, aerosol formation around Milan seems to be similarly dependent on HNO3 and NH3 most of the time. However, there are times when limitation by NH3 is stronger. The contribution of biogenic sources to SOA was predicted to be rather high, about 80% in the north, matching the measurements whereas it was lower in southern Switzerland (40%).
Cerebral Autoregulation: An Overview of Current Concepts and Methodology with Special Focus on the Elderly
Authors: van Beek Arenda HEA , Claassen Jurgen AHR , Rikkert Marcel GM Olde , Jansen René WMM
Published: March 2008

Cerebral autoregulation (CA) refers to the properties of the brain vascular bed to maintain cerebral perfusion despite changes in blood pressure ( BP). Whereas classic studies have assessed CA during changes in BP that have a gradual onset, dynamic studies quantify the fast modifications in cerebral blood flow ( CBF) in relation to rapid alterations in BP. There is a lack of standardization in the assessment of dynamic CA. This review provides an overview of the methods that have been applied, with special focus on the elderly. We will discuss the relative merits and shortcomings of these methods with regard to the aged population. Furthermore, we summarize the effects of variability in BP on CBF in older people. Of the various dynamic assessments of CA, a single sit-to-stand procedure is a feasible and physiologic method in the elderly. The collection of spontaneous beat-to-beat changes in BP and CBF allows estimation of CA using the technique of transfer function analysis. A thorough search of the literature yielded eight studies that have measured dynamic CA in the elderly aged <75 years. Regardless of the methods used, it was concluded from these studies that CA was preserved in this population.
Coordinated Nuclear Receptor Regulation of the Efflux Transporter, Mrp2, and the Phase-Ii Metabolizing Enzyme, GSTπ, at the Blood—Brain Barrier
Authors: Bauer Björn , Hartz Anika M S , Lucking Jonathan R , Yang Xiaodong , Pollack Gary M , Miller David S
Published: March 2008

Xenobiotic efflux pumps at the blood—brain barrier are critical modulators of central nervous system pharmacotherapy. We previously found expression of the ligand-activated nuclear receptor, pregnane X receptor (PXR), in rat brain capillaries, and showed increased expression and transport activity of the drug efflux transporter, P-glycoprotein, in capillaries exposed to PXR ligands (pregnenolone-16α-carbonitrile (PCN) and dexamethasone) in vitro and in vivo. Here, we show increased protein expression and transport activity of another efflux pump, multidrug resistance-associated protein isoform 2 (Mrp2), in rat brain capillaries after in vitro and in vivo exposure to PCN and dexamethasone. The phase-II drug-metabolizing enzyme, glutathione S-transferase-π (GSTπ), was found to be expressed in brain capillaries, where it colocalized to a large extent with Mrp2 at the endothelial cell luminal plasma membrane. Like Mrp2, GSTπ protein expression increased with PXR activation. Colocalization and coordinated upregulation suggest functional coupling of the metabolizing enzyme and efflux transporter. These findings indicate that, as in hepatocytes, brain capillaries possess a regulatory network consisting of nuclear receptors, metabolizing enzymes, and efflux transporters, which modulate blood—brain barrier function.
Speciation of chilean Rhinocryptidae (Avian) based on their behaviour
Authors: Correa Rueda Alejandro , Mpodozis Jorge
Published: March 2008

The current classification of the chilean representatives of the passerine family Rhinocryptidae includes eight species. Three of them contain subspecies that don’t exhibit clear differences. Moreover, differences among two lineages of Scytalopus genera and two species of Pteroptochos are very scarce. We propose a new methodology based on ecological and behavioural patterns in order to understand the concept of speciation in this group of birds. According to our results, we postulate that there is not a cut criteria to establish differences among three sister lineages of current classification. This way the methodology developed by us does not allow to establish divergence for a given common ancestor. Our methodology allows to establish comparison among previously determined phylogenetic lineages. Our results show how when integrating behaviour and ecological terms as biological traits next to morphological characters of the plumage, it allows us to conclude that there is decrease of the distances among sister lineages in the cluster tree.
A transient forward‐targeting element for microneme‐regulated secretion in Toxoplasma gondii
Authors: Brydges Susannah D. , Harper Jill M. , Parussini Fabiola , Coppens Isabelle , Carruthers Vern B.
Published: March 2008

Background information. Accurate sorting of proteins to the three types of secretory granules in Toxoplasma gondii is crucial for successful cell invasion by this obligate intracellular parasite. As in other eukaryotic systems, propeptide sequences are a common yet poorly understood feature of proteins destined for regulated secretion, which for Toxoplasma occurs through two distinct invasion organelles, rhoptries and micronemes. Microneme discharge during parasite apical attachment plays a pivotal role in cell invasion by delivering adhesive proteins for host receptor engagement.

Results. We show here that the small micronemal proprotein MIC5 (microneme protein‐5) undergoes proteolytic maturation at a site beyond the Golgi, and only the processed form of MIC5 is secreted via the micronemes. Proper cleavage of the MIC5 propeptide relies on an arginine residue in the P1′ position, although P1′ mutants are still cleaved to a lesser extent at an alternative site downstream of the primary site. Nonetheless, this aberrantly cleaved species still correctly traffics to the micronemes, indicating that correct cleavage is not necessary for micronemal targeting. In contrast, a deletion mutant lacking the propeptide was retained within the secretory system, principally in the ER (endoplasmic reticulum). The MIC5 propeptide also supported correct trafficking when exchanged for the M2AP propeptide, which was recently shown to also be required for micronemal trafficking of the TgMIC2 (T. gondii MIC2)–M2AP complex [Harper, Huynh, Coppens, Parussini, Moreno and Carruthers (2006) Mol. Biol. Cell 17, 4551–4563].

Conclusion. Our results illuminate common and unique features of micronemal propeptides in their role as trafficking facilitators.