Untersuchung einer neuen Herzklappe für Herzunterstützungssysteme

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Ein bewährtes Verfahren zur Behandlung erkrankter natürlicher Heizklappen ist die Implantation von Heizklappenprothesen. Neben diesem Einsatz entwickelt sich zur Zeit ein weiteres Anwendungsgebiet; der Einsatz von Herzklappenprothesen in Herzunterstützungssystemen. Eine häufig dabei auftretende Komplikation stellt die Thrombenbildung dar. Diese tritt insbesondere im Bereich der verwendeten Herzklappenprothesen auf. Bei einer Implantation einer Heizklappenprothese ist ihre unmittelbare Umgebung durch die Anatomie vorgegeben. Bei einem Einsatz in einem Herzunterstützungssystem dagegen kann diese Umgebung frei gestaltet werden. Mit diesem Ansatz ergeben sich für die strömungstechnische Gestaltung der Herzklappen für Blutpumpen ganz neue Möglichkeiten. Die unmittelbare Umgebung der Klappe ist der Strömungskanal. Mit dem neuen, hier vorgestellten S-förmigen Strömungskanal der Klappe scheint es möglich zu sein, die Gefahr der Thrombenbildung zu reduzieren. Insbesondere die Vermeidung von Ablösungen führt zu einer Verringerung des Risikos der Thrombenbildung und ermöglicht damit eine verminderte Dosierung von Antikoagulantien

Confinement of sows for different periods during lactation: effects on behaviour and lesions of sows and performance of piglets.

Alternatives to farrowing crates with continuous confinement of the sow are urgently needed because the animal welfare is negatively impacted. Given the increase of herd sizes, practical experience with loose-housing is needed to force the implementation of these systems in the field. Next to aspects of labour efficiency, detrimental piglet mortality rates that may occur during the first days postpartum (pp) is a major criticism. Therefore, loose-housing after a crating period limited to the first days pp might be a feasible alternative to improve welfare under intensive production conditions. The aim was to investigate the effect of crating sows during lactation for different periods on their behaviour and integument alterations and on piglets' performance. Gilts from a commercial herd were observed from 5 to 26 days pp and housed in farrowing crates (1.85×2.50 m) that could be altered between confinement crates and loose-housing pens. Animals were divided into three groups, that were either crated continuously from birth until weaning (Group A, n=55), until 14 days pp (Group B; n=54) or 7 days pp (Group C, n=59). The behaviour of six randomly selected gilts per group was video recorded from 5 to 26 days pp and analysed by time sampling technique. Lesions on the legs, shoulder and lumbar vertebra were scored on days 7, 14 and 25 pp. Piglets were weighed weekly, causes of losses recorded and weight losses of gilts measured. Not different between groups (P>0.05), animals spent 72 to 76% lying laterally, 14 to 17% lying in abdominal or semi-abdominal position, 9 to 10% standing and 1 to 3% sitting. B-sows were lying longer in week 3 and 4 of lactation compared to A- and C-sows (P0.05), whereas almost 90% of the losses occurred in the first week pp. In conclusion, loose-housing of lactating gilts after a reduced postnatal crating period of 7 days affected neither the activity level of the gilts and lesions on the integument nor pre-weaning mortality. Therefore, it is recommended to allow sows to move around to some extent during the later lactation period

Algorithmic Interpretations of Fractal Dimension

We study algorithmic problems on subsets of Euclidean space of low fractal dimension. These spaces are the subject of intensive study in various branches of mathematics, including geometry, topology, and measure theory. There are several well-studied notions of fractal dimension for sets and measures in Euclidean space. We consider a definition of fractal dimension for finite metric spaces which agrees with standard notions used to empirically estimate the fractal dimension of various sets. We define the fractal dimension of some metric space to be the infimum delta>0, such that for any eps>0, for any ball B of radius r >= 2eps, and for any eps-net N, we have |B cap N|=O((r/eps)^delta). Using this definition we obtain faster algorithms for a plethora of classical problems on sets of low fractal dimension in Euclidean space. Our results apply to exact and fixed-parameter algorithms, approximation schemes, and spanner constructions. Interestingly, the dependence of the performance of these algorithms on the fractal dimension nearly matches the currently best-known dependence on the standard Euclidean dimension. Thus, when the fractal dimension is strictly smaller than the ambient dimension, our results yield improved solutions in all of these settings. We remark that our definition of fractal definition is equivalent up to constant factors to the well-studied notion of doubling dimension. However, in the problems that we consider, the dimension appears in the exponent of the running time, and doubling dimension is not precise enough for capturing the best possible such exponent for subsets of Euclidean space. Thus our work is orthogonal to previous results on spaces of low doubling dimension; while algorithms on spaces of low doubling dimension seek to extend results from the case of low dimensional Euclidean spaces to more general metric spaces, our goal is to obtain faster algorithms for special pointsets in Euclidean space

Pharmacological inhibition of cyclin-dependent kinases triggers anti-fibrotic effects in hepatic stellate cells in vitro

Liver fibrosis is a wound healing process in response to chronic liver injury, which is characterized by the accumulation of extracellular collagen produced by Hepatic Stellate Cells (HSCs). This process involves cell cycle re-entry and proliferation of normally quiescent HSCs controlled by cyclins and associated cyclin-dependent kinases (Cdks). Cdk2 mediates the entry and progression through S-phase in complex with E-and A-type cyclins. We have demonstrated that cyclin E1 is essential for liver fibrogenesis in mice, but it is not known if this is dependent on Cdk2 or related Cdks. Here, we aimed to evaluate the benefit of the pan-Cdk inhibitor CR8 for treatment of liver fibrosis in vitro. CR8-treatment reduced proliferation and survival in immortalized HSC lines and in addition attenuated pro-fibrotic properties in primary murine HSCs. Importantly, primary murine hepatocytes were much more tolerant against the cytotoxic and anti-proliferative effects of CR8. We identified CR8 dosages mediating anti-fibrotic effects in primary HSCs without affecting cell cycle activity and survival in primary hepatocytes. In conclusion, the pharmacological pan-Cdk inhibitor CR8 restricts the pro-fibrotic properties of HSCs, while preserving proliferation and viability of hepatocytes at least in vitro. Therefore, CR8 and related drugs might be beneficial for the treatment of liver fibrosis

Language ability in preterm children is associated with arcuate fasciculi microstructure at term

In the mature human brain, the arcuate fasciculus mediates verbal working memory, word learning, and sublexical speech repetition. However, its contribution to early language acquisition remains unclear. In this work, we aimed to evaluate the role of the direct segments of the arcuate fasciculi in the early acquisition of linguistic function. We imaged a cohort of 43 preterm born infants (median age at birth of 30 gestational weeks; median age at scan of 42 postmenstrual weeks) using high b value high-angular resolution diffusion-weighted neuroimaging and assessed their linguistic performance at 2 years of age. Using constrained spherical deconvolution tractography, we virtually dissected the arcuate fasciculi and measured fractional anisotropy (FA) as a metric of white matter development. We found that term equivalent FA of the left and right arcuate fasciculi was significantly associated with individual differences in linguistic and cognitive abilities in early childhood, independent of the degree of prematurity. These findings suggest that differences in arcuate fasciculi microstructure at the time of normal birth have a significant impact on language development and modulate the first stages of language learning

A spectrum deconvolution method based on grey relational analysis

The extensive usage of X ray spectroscopies in studying complex material systems is not only intended to reveal underlying mechanisms that govern physical phenomena, but also used in applied studies focused on an insight driven performance improvement of a wide range of devices. However, the traditional analysis methods for X ray spectroscopic data are rather time consuming and sensitive to errors in data pre processing e.g., normalization or background subtraction . In this study, a method based on grey relational analysis, a multi variable statistical method, is proposed to analyze and extract information from X ray spectroscopic data. As a showcase, the valence bands of microcrystalline silicon suboxides probed by hard X ray photoelectron spectroscopy HAXPES were investigated. The results obtained by the proposed method agree well with conventionally derived composition information e.g., curve fit of Si 2p core level of the silicon suboxides . Furthermore, the uncertainty of chemical compositions derived by the proposed method is smaller than that of traditional analysis methods e.g., the least square fit , when artificial linear functions are introduced to simulate the errors in data pre processing. This suggests that the proposed method is capable of providing more reliable and accurate results, especially for data containing significant noise contributions or that is subject to inconsistent data pre processing. Since the proposed method is less experience driven and error prone, it offers a novel approach for automate data analysis, which is of great interest for various applications, such as studying combinatorial material librarie

Multi-level evidence of an allelic hierarchy of USH2A variants in hearing, auditory processing and speech/language outcomes.

Language development builds upon a complex network of interacting subservient systems. It therefore follows that variations in, and subclinical disruptions of, these systems may have secondary effects on emergent language. In this paper, we consider the relationship between genetic variants, hearing, auditory processing and language development. We employ whole genome sequencing in a discovery family to target association and gene x environment interaction analyses in two large population cohorts; the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK10K. These investigations indicate that USH2A variants are associated with altered low-frequency sound perception which, in turn, increases the risk of developmental language disorder. We further show that Ush2a heterozygote mice have low-level hearing impairments, persistent higher-order acoustic processing deficits and altered vocalizations. These findings provide new insights into the complexity of genetic mechanisms serving language development and disorders and the relationships between developmental auditory and neural systems

Paramagnetic centers in amorphous and microcrystalline silicon irradiated with 2 МeV electrons

Amorphous and microcrystalline silicon are well known materials for thin film large area electronics. The defects in the material are an important issue for the device quality and the manufacturing process optimization. We study defects in thin film silicon with electron spin resonance (ESR). In order to vary the defect density in a wide range 2 MeV electron bombardment at 100 K was applied with dose as high as 10¹⁸ e*cm⁻². Samples were investigated after deposition, after irradiation and between the annealing steps. The spin density (Ns) in the material was varied over 3 orders of magnitude. Strong satellites with g≈2.010 and g≈2.000 were observed on the shoulders of the dangling bond line. The initial Ns and the shape of the resonance line were restored after annealing.Аморфний і мікрокристалічний кремній є широко відомими матеріалами для виробництва тонкоплівкової електроники великої площі. Дефекти у даних матеріалах відіграють вирішальну роль для якості пристроїв і оптимізації виробничих процесів. Ми досліджували тонкоплівковий гідрогенований кремній методом вимірів електронного парамагнитного резонансу (ЕПР). Для зміни щільності дефектів у широкому диапазоні зразки було опромінено електронами з енергією 2 МеВ. Зразки було досліджено після осадження, після опромінення і між етапами відпалу. Щільність спинів (Ns) в матеріалі змінювалась в межах 3-х порядків величини. З обох боків від центрального резонансу, що характеризує обірвані зв’язки кремнію, спостеригались потужні додаткові резонансні лінії (g≈2.010 и g≈2.000). Після відпалу форма резонансних ліній і щільність спинів поверталися до вихідних показників.Аморфный и микрокристаллический кремний являются широко известными материалами для производства тонкопленочной электроники большой площади. Дефекты в данных материалах играют решающую роль для качества приборов и оптимизации производственных процессов. Мы исследовали тонкопленочный гидрогенированный кремний методом измерений электронного парамагнитного резонанса (ЭПР). Для изменения плотности дефектов в широких пределах образцы облучались электронами с энергией 2 МэВ. Образцы исследовались после осаждения, после облучения и между стадиями отжига. Плотность спинов (Ns) в материале изменялась в пределах 3-х порядков величины. По обе стороны от центрального резонанса, характеризующего оборванные связи кремния, наблюдались мощные дополнительные резонансные линии (g≈2.010 и g≈2.000). После отжига форма резонансных линий и плотность спинов возвращались к исходным значениям