Modeling of Transmission Functions and Crosstalk in Metallic Cables for Implementation of MIMO Concept

The new promising wireless networks based on multi-carrier modulations (MCM) and multiple-input multiple-output concept (MIMO) will soon offer high-speed digital connections. Their access points are mostly connected by fixed metallic lines to core data and telecommunication networks. That is why it will also be necessary to increase the transmission speed and overall performance of these fixed access networks adequately in order to meet the expected requirements of wireless connections. It would be possible to use VDSL2 digital subscriber lines and implement MIMO concept into the existing metallic networks for this purpose, but before that it will be necessary to solve several problems first. The transmission capacity of present VDSL2 digital lines is limited mainly by crosstalk occurring in metallic cables. This paper describes a new method for modeling of transmission functions and crosstalk in multi-pair and multi-quad metallic cables including its mathematical implementation, and it also gives an example of results obtained so far. The presented model is based on statistical evaluations of measured values, generation of pseudo-random components of frequency response and subsequent filtration process

Survey of Toxoplasma gondii antibodies in meat juice of wild boar (Sus scrofa) in several districts of the Czech Republic

Introduction and objective The aims of the study were: 1) to detect antibodies against Toxoplasma gondii from wild boar meat; 1) establish seroprevalence of toxoplasmosis in the wild boar population; 3) establish risk factors concerned in higher possible seroprevalence; 4) to estimate the usefulness of meat juice for detection of T. gondii antibodies in wild boar. Material and Methods Diaphragm meat juice samples from 656 wild boar (Sus scrofa) were collected during the hunting seasons between September 2008 – October 2010 from 9 districts of the Czech Republic. The samples were stratified per age category into 2 groups: piglets (n = 279) and yearlings together with adults (n = 377). The in-house ELISA test was used for the detection of antibodies against T. gondii from the meat juice samples. Results Antibodies against T. gondii were detected by in-house ELISA in 260 of 656 wild boars (40%) with 26% prevalence in piglets (72/279) and 50% prevalence in yearlings and adults (188/377). The district total seroprevalences ranged between 32% – 59%, with a significantly higher prevalence in the district of Havlíčkův Brod (59%). Statistically significant differences (p-value < 0.05) were found between 2 age categories, and between 9 districts, with a significant variability in the district of Havlíčkův Brod. Seroprevalence correlated positively with farm density, but without any statistical significance. Conclusions The obtained results indicate that consumption of raw or undercooked meat from wild boars can carry an important risk of toxoplasma infection. Post mortem detection of antibodies in meat juice samples using ELISA is a useful alternative to blood serum examination. In addition, a diaphragm sample has been well-proven as a matrix sample for the contemporaneous diagnostics of trichinellosis and toxoplasmosis

First record of chambered hexactinellid sponges from the Palaeozoic

A new chambered hexactinellid sponge, Casearia devonica sp. nov., is described from the Lower Devonian of northern Spain (Cantabrian Mountains). The fossil represents the first evidence of chambered hexactinellid sponges from the Palaeozoic and the oldest representative of the order Hexactinosida. Casearia devonica sp. nov. occurred within small metre-sized mud mounds that developed in deeper water below the storm wave base

College-wide Senior Design Competition: A Motivating Approach

Up until five years ago, capstone senior design project in the Howard R. Hughes College of Engineering, University of Nevada, Las Vegas, was mostly an individual student effort. Students were not necessarily expected to produce a working prototype by the end of one year capstone course. With a view to encourage commercially viable interdisciplinary and motivate the students to bring out their creative spirit without fear of lack of resources, our college began a college-wide senior design competition at the end of every semester. The competition is sponsored by Harriet and Fred Cox, a local philanthropist. The departments of Civil and Environmental Engineering, Electrical and Computer Engineering, and Mechanical Engineering offer two-course sequence senior design courses. By the end of the first semester, students should finalize their design and present a budget for creating a prototype in the second semester. Typically, a project is funded up to 85% of its total cost. At the end of the second semester, students have to participate in the competition by presenting their project along with a poster summarizing the highlights of their design. The projects and the posters are evaluated by three or four engineers from the local industry. The criteria for evaluation are: (i) innovation, (ii) potential for commercialization/ implementation, (iii) technical merit, (iv) clarity and soundness of the project, (v) oral presentation and (vi) poster presentation. Interdisciplinary projects are given a separate award. Additionally, the judges are given the opportunity to provide us their thoughts individually and collectively as a group. The evaluation data and comments are passed back to the students as a constructive feedback. Prize monies raging from $2500 to$500 along with medallions are awarded to the winners in an industrially sponsored “Senior Design Dinner” event in May, every year. This event is usually attended by about 300 local entrepreneurs and engineers and features an entrepreneur as a keynote speaker. The data is also used as one of the tools of external evaluation of our undergraduate degree programs for ABET purposes. Based on our past experiences, we are in the process of developing a Technology Commercialization Minor. We will also encourage students to participate in a state-wide Business Plan competition

The semaphorin 4D-plexin-B signalling complex regulates dendritic and axonal complexity in developing neurons via diverse pathways.

Semaphorins and their receptors, plexins, have emerged as key regulators of various aspects of neuronal development. In contrast to the Plexin-A family, the cellular functions of Plexin-B family proteins in developing neurons are only poorly understood. An activation of Plexin-B1 via its ligand, semaphorin 4D (Sema4D), produces an acute collapse of axonal growth cones in hippocampal and retinal neurons over the early stages of neurite outgrowth. However, the functional role of Sema4D-Plexin-B interactions over subsequent stages of neurite development, differentiation and maturation has not been characterized. Here we addressed this question using morphogenetic assays and time-lapse imaging on developing rat hippocampal neurons as a model system. Interestingly, Sema4D treatment over several hours was observed to promote branching and complexity in hippocampal neurons via the activation of Plexin-B1. The activation of receptor tyrosine kinases and the Rho kinase following Sema4D treatment was found to control dendritic and axonal morphogenesis by differentially regulating branching and extension. Phosphoinositide-3-kinase, but not extracellular signal-regulated kinase 1/2, was observed to be important for the stimulatory effects of Sema4D on dendritic branching. Furthermore, we observed that the mammalian target of rapamycin is activated downstream of Plexin-B1 and contributes to Sema4D-induced effects on dendritic branching. In contrast, glycogen synthase kinase-3 beta, another effector of phosphoinositide-3-kinase signalling, was not involved. Thus, our results show that Sema4D-Plexin-B interactions modulate dendritic and axonal arborizations of developing neurons by co-ordinated and concerted activation of diverse signalling pathways

A functional role for semaphorin 4D/plexin B1 interactions in epithelial branching morphogenesis during organogenesis.

Semaphorins and their receptors, plexins, carry out important functions during development and disease. In contrast to the well-characterized plexin A family, however, very little is known about the functional relevance of B-type plexins in organogenesis, particularly outside the nervous system. Here, we demonstrate that plexin B1 and its ligand Sema4d are selectively expressed in epithelial and mesenchymal compartments during key steps in the genesis of some organs. This selective expression suggests a role in epithelial-mesenchymal interactions. Importantly, using the developing metanephros as a model system, we have observed that endogenously expressed and exogenously supplemented Sema4d inhibits branching morphogenesis during early stages of development of the ureteric collecting duct system. Our results further suggest that the RhoA-ROCK pathway, which is activated downstream of plexin B1, mediates these inhibitory morphogenetic effects of Sema4d and suppresses branch-promoting signalling effectors of the plexin B1 signalling complex. Finally, mice that lack plexin B1 show early anomalies in kidney development in vivo. These results identify a novel function for plexin B1 as a negative regulator of branching morphogenesis during kidney development, and suggest that the Sema4d-plexin B1 ligand-receptor pair contributes to epithelial-mesenchymal interactions during organogenesis via modulation of RhoA signalling

Gene Deletion Mutants Reveal a Role for Semaphorin Receptors of the Plexin-B Family in Mechanisms Underlying Corticogenesis ▿

Semaphorins and their receptors, plexins, are emerging as key regulators of various aspects of neural and nonneural development. Semaphorin 4D (Sema4D) and B-type plexins demonstrate distinct expression patterns over critical time windows during the development of the murine neocortex. Here, analysis of mice genetically lacking plexin-B1 or plexin-B2 revealed the significance of Sema4D-plexin-B signaling in cortical development. Deficiency of plexin-B2 resulted in abnormal cortical layering and defective migration and differentiation of several subtypes of cortical neurons, including Cajal-Retzius cells, GABAergic interneurons, and principal cells in vivo. In contrast, a lack of plexin-B1 did not impact on cortical development in vivo. In various ex vivo assays on embryonic forebrain, Sema4D enhanced the radial and tangential migration of developing neurons in a plexin-B2-dependent manner. These results suggest that Sema4D-plexin-B2 interactions regulate mechanisms underlying cell specification, differentiation, and migration during corticogenesis

Plexin-B2, but not Plexin-B1, critically modulates neuronal migration and patterning of the developing nervous system in vivo

Semaphorins and their receptors, plexins, have emerged as important cellular cues regulating key developmental processes. B-type plexins directly regulate the actin cytoskeleton in a variety of cell types. Recently, B-type plexins have been shown to be expressed in striking patterns in the nervous system over critical developmental windows. However, in contrast to the well characterized plexin-A family, the functional role of plexin-B proteins in neural development and organogenesis in vertebrates in vivo is not known. Here, we have elucidated the functional contribution of the two neuronally expressed plexin-B proteins, Plexin-B1 or Plexin-B2, toward the development of the peripheral nervous system and the CNS by generating and analyzing constitutive knock-out mice. The development of the nervous system was found to be normal in mice lacking Plexin-B1, whereas mice lacking Plexin-B2 demonstrated defects in closure of the neural tube and a conspicuous disorganization of the embryonic brain. After analyzing mutant mice, which bypassed neural tube defects, we observed a key requirement for Plexin-B2 in proliferation and migration of granule cell precursors in the developing dentate gyrus, olfactory bulb, and cerebellum. Furthermore, we identified semaphorin 4C as a high-affinity ligand for Plexin-B2 in binding and functional assays. Semaphorin 4C stimulated activation of ErbB-2 and RhoA via Plexin-B2 and enhanced proliferation and migration of granule cell precursors. Semaphorin 4C-induced proliferation of ventricular zone neuroblasts was abrogated in mice lacking Plexin-B2. These genetic and functional analyses reveal a key requirement for Plexin-B2, but not Plexin-B1, in patterning of the vertebrate nervous system in vivo

Gene deletion mutants reveal a role for semaphorin receptors of the plexin-B family in mechanisms underlying corticogenesis

Semaphorins and their receptors, plexins, are emerging as key regulators of various aspects of neural and nonneural development. Semaphorin 4D (Sema4D) and B-type plexins demonstrate distinct expression patterns over critical time windows during the development of the murine neocortex. Here, analysis of mice genetically lacking plexin-B1 or plexin-B2 revealed the significance of Sema4D-plexin-B signaling in cortical development. Deficiency of plexin-B2 resulted in abnormal cortical layering and defective migration and differentiation of several subtypes of cortical neurons, including Cajal-Retzius cells, GABAergic interneurons, and principal cells in vivo. In contrast, a lack of plexin-B1 did not impact on cortical development in vivo. In various ex vivo assays on embryonic forebrain, Sema4D enhanced the radial and tangential migration of developing neurons in a plexin-B2-dependent manner. These results suggest that Sema4D-plexin-B2 interactions regulate mechanisms underlying cell specification, differentiation, and migration during corticogenesis