Abnormal arterial-venous fusions and fate specification in mouse embryos lacking blood flow.

The functions of blood flow in the morphogenesis of mammalian arteries and veins are not well understood. We examined the development of the dorsal aorta (DA) and the cardinal vein (CV) in Ncx1 -/- mutants, which lack blood flow due to a deficiency in a sodium calcium ion exchanger expressed specifically in the heart. The mutant DA and CV were abnormally connected. The endothelium of the Ncx1 -/- mutant DA lacked normal expression of the arterial markers ephrin-B2 and Connexin-40. Notch1 activation, known to promote arterial specification, was decreased in mutant DA endothelial cells (ECs), which ectopically expressed the venous marker Coup-TFII. These findings suggest that flow has essential functions in the DA by promoting arterial and suppressing venous marker expression. In contrast, flow plays a lesser role in the CV, because expression of arterial-venous markers in CV ECs was not as dramatically affected in Ncx1 -/- mutants. We propose a molecular mechanism by which blood flow mediates DA and CV morphogenesis, by regulating arterial-venous specification of DA ECs to ensure proper separation of the developing DA and CV

Die Rechtsform des virtuellen Unternehmens - die juristischen Folgen des grenzenlosen Unternehmens

Aus Punkt 1: "Virtuelle Unternehmen sind das Ergebnis eines ökonomischen, zweckorientierten Optimierungsprozesses. Die modernen Informations- und Kommunikationstechnologien eröffnen Unternehmen neue Handlungsoptionen in der Gestaltung ihrer betrieblichen Funktionen. Ein Anwendungsfeld dieser neuen Techniken ist die Neustrukturierung der Zusammenarbeit innerhalb und außerhalb des Unternehmens. Untemehmensgrenzen können so verwischt oder aufgelöst werden. Neue, vernetzte Strukturen entstehen36.

Avian Cone Photoreceptors Tile the Retina as Five Independent, Self-Organizing Mosaics

The avian retina possesses one of the most sophisticated cone photoreceptor systems among vertebrates. Birds have five types of cones including four single cones, which support tetrachromatic color vision and a double cone, which is thought to mediate achromatic motion perception. Despite this richness, very little is known about the spatial organization of avian cones and its adaptive significance. Here we show that the five cone types of the chicken independently tile the retina as highly ordered mosaics with a characteristic spacing between cones of the same type. Measures of topological order indicate that double cones are more highly ordered than single cones, possibly reflecting their posited role in motion detection. Although cones show spacing interactions that are cell type-specific, all cone types use the same density-dependent yardstick to measure intercone distance. We propose a simple developmental model that can account for these observations. We also show that a single parameter, the global regularity index, defines the regularity of all five cone mosaics. Lastly, we demonstrate similar cone distributions in three additional avian species, suggesting that these patterning principles are universal among birds. Since regular photoreceptor spacing is critical for uniform sampling of visual space, the cone mosaics of the avian retina represent an elegant example of the emergence of adaptive global patterning secondary to simple local interactions between individual photoreceptors. Our results indicate that the evolutionary pressures that gave rise to the avian retina's various adaptations for enhanced color discrimination also acted to fine-tune its spatial sampling of color and luminance

Rare plant conservation planning workshop results: Pagosa Springs

This document identifies conservation strategies for Pagosa skyrocket, based on an assessment of the plant's viability and threats by participants of a June 2008 workshop. The primary audience is intended to be the workshop participants and other stakeholders interested in helping to implement the strategies.Sponsored by the Colorado Rare Plant Conservation Initiative, June 12, 2008

Bedrock weathering and stream water chemistry in felsic and ultramafic forest catchments

Abstract not availablePavel Krám, Juraj Farkaš, Anna Pereponova, Chukwudi Nwaogu, Veronika Štědrá, Jakub Hrušk

Scenarios as the basis for assessment of mitigation and adaptation

The possibilities and need for adaptation and mitigation depends on uncertain future developments with respect to socio-economic factors and the climate system. Scenarios are used to explore the impacts of different strategies under uncertainty. In this chapter, some scenarios are presented that are used in the ADAM project for this purpose. One scenario explores developments with no mitigation, and thus with high temperature increase and high reliance on adaptation (leading to 4oC increase by 2100 compared to pre-industrial levels). A second scenario explores an ambitious mitigation strategy (leading to 2oC increase by 2100 compared to pre-industrial levels). In the latter scenario, stringent mitigation strategies effectively reduces the risks of climate change, but based on uncertainties in the climate system a temperature increase of 3oC or more cannot be excluded. The analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but even then adaptation will be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which adaptation is more cost-effective than mitigation, but mitigation can help reduce damages and the cost of adaptation. For agriculture, finally, only the scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts

Geographic Distribution of Maternal Group B Streptococcus Colonization and Infant Death During Birth Hospitalization: Eastern Wisconsin

Purpose: Maternal group B Streptococcus (GBS) can be transmitted from a colonized mother to newborn during vaginal delivery and may or may not contribute to infant death. This study aimed to explore the geographic distribution and risk factors of maternal GBS colonization and infant death during birth hospitalization. Methods: We retrospectively studied mothers with live birth(s) in a large eastern Wisconsin hospital system from 2007 through 2013. Associations between maternal and neonatal variables, GBS colonization and infant death were examined using chi-squared, Mann-Whitney U and t-tests. Multivariable logistic regression models also were developed. Results: Study population (N = 99,305) had a mean age of 28.1 years and prepregnancy body mass index (BMI) of 26.7 kg/m2; 64.0% were white, 59.2% married, 39.3% nulliparous and 25.7% cesarean delivery. Mean gestational age was 39.0 weeks. Rate of maternal GBS colonization (22.3% overall) was greater in blacks (34.1% vs. 20.1% in whites, P < 0.0001), unmarried women (25.5% vs. 20.0% married, P < 0.0001), women with sexually transmitted or other genital infections (P < 0.0001) and residents of ZIP code group 532XX (P < 0.0001), and was associated with increasing BMI (P < 0.0001). All predictors of colonization were significant on multivariable analysis. Rate of infant death was 5.7 deaths/1,000 live births (n = 558 excluding lethal anomalies and stillbirths) and was negatively associated with maternal GBS colonization (P < 0.0001). On multivariable analysis, 532XX ZIP code group, lower gestational age, preterm labor, hyaline membrane disease, normal spontaneous vaginal delivery, hydramnios, oligohydramnios and absence of maternal GBS were associated with infant death. Conclusions: Geographic characteristics were associated with infant death and maternal GBS colonization. Further research is needed to determine if increased surveillance or treatment of mothers colonized with GBS decreases the risk of infant demise at birth

Improving the Bit Error Rate Performance of Free Space Optical Communication due to Atmospheric Turbulence Effect using New Double Multiple-Input Multiple-Output Technique

This paper focus on mitigating the atmospheric turbulence effect in free space optical (FSO) communications by using double multiple input multiple output (DMIMO)technique. This technique is an enhancement of the conventional multiple input multiple output (MIMO) technique in improving the performance of FSO system. The combination of double MIMO with differential detection mode at the receiver resulting in superior modulation against the turbulence especially in reducing the scintillation index, enhance the power received and improve the threshold signal level. The analysis result shows that under strong turbulence conditions, the bit error rate can be improved by 20 percent in terms of free space optical distance propagation

The role of mentorship in protege performance

The role of mentorship on protege performance is a matter of importance to academic, business, and governmental organizations. While the benefits of mentorship for proteges, mentors and their organizations are apparent, the extent to which proteges mimic their mentors' career choices and acquire their mentorship skills is unclear. Here, we investigate one aspect of mentor emulation by studying mentorship fecundity---the number of proteges a mentor trains---with data from the Mathematics Genealogy Project, which tracks the mentorship record of thousands of mathematicians over several centuries. We demonstrate that fecundity among academic mathematicians is correlated with other measures of academic success. We also find that the average fecundity of mentors remains stable over 60 years of recorded mentorship. We further uncover three significant correlations in mentorship fecundity. First, mentors with small mentorship fecundity train proteges that go on to have a 37% larger than expected mentorship fecundity. Second, in the first third of their career, mentors with large fecundity train proteges that go on to have a 29% larger than expected fecundity. Finally, in the last third of their career, mentors with large fecundity train proteges that go on to have a 31% smaller than expected fecundity.Comment: 23 pages double-spaced, 4 figure