Chick PTPσ regulates the targeting of retinal axons within the optic tectum

Chick PTP (cPTP), also known as CRYP, is a receptor-like protein tyrosine phosphatase found on axons and growth cones. Putative ligands for cPTP are distributed within basement membranes and on glial end feet of the retina, optic nerve, and optic tectum, suggesting that cPTP signaling is occurring along the whole retinotectal pathway. We have shown previously that cPTP plays a role in supporting the retinal phase of axon outgrowth. Here we have now addressed the role of cPTP within retinal axons as they undergo growth and topographic targeting in the optic tectum. With the use of retroviruses, a secretable cPTP ectodomain was ectopically expressed in ovo in the developing chick optic tectum, with the aim of directly disrupting the function of endogenous cPTP. In ovo, the secreted ectodomains accumulated at tectal sites in which cPTP ligands are also specifically found, suggesting that they are binding to these endogenous ligands. Anterograde labeling of retinal axons entering these optic tecta revealed abnormal axonal phenotypes. These included the premature stalling and arborization of fibers,excessive pretectal arbor formation, and diffuse termination zones. Most of the defects were rostral of the predicted termination zone, indicating that cPTP function is necessary for sustaining the growth of retinal axons over the optic tectum and for directing axons to their correct sites of termination. This demonstrates that regulation of cPTP signaling in retinal axons is required for their topographic mapping, the first evidence of this function for a receptor-like protein tyrosine phosphatase in the retinotectal projection

IS AGRICULTURAL SECTOR GROWTH A PRECONDITION FOR ECONOMIC GROWTH? THE CASE OF SOUTH AFRICA

In this paper a simple growth model is adapted to explain the effect of the agricultural sectors' growth on the non-agricultural sector. The empirical results suggest that for a 1% growth in the agricultural sector, the non-agricultural sector responds by more than 1%. The results also confirm that productivity difference exists, the non-agricultural sector being more efficient in terms of input use. The empirical results support the argument of President T. Mbeki, that South Africa should follow an "agricultural-led" growth strategy for successful development.International Development,

Reliability of a Shuttle reaction timer

Reaction, movement, and task times refer to the times needed to initially respond to a stimulus, make the specific movement, and complete the entire task. This study evaluated the reliability of a simple reaction timer designed to mimic a Space Shuttle task (turning on an overhead switch)

Twelve Tips for specialists teaching generalists

Generalist clinicians play a vital role as the spine of a modern healthcare system. As a result of the breadth of their practice, they require high quality continuous professional development (CPD) training to keep up with important developments in all areas of their practice. Specialist clinicians are often well placed to provide such training but should recognise the ways in which this may differ from undergraduate and postgraduate training, and design tailored education that takes account of power dynamics, professional roles, and contemporary healthcare challenges. Prior engagement with the learning group to understand their aims and priorities is a crucial first step. Case-based learning, practical diagnostic and referral tips, patient communication and information advice, prioritising discussion and feedback, and reflecting on changes in evidence and guidelines are all suggested areas of focus that can provide a framework to design effective and engaging training for generalist groups

Testing collapse models with levitated nanoparticles: the detection challenge

We consider a nanoparticle levitated in a Paul trap in ultrahigh cryogenic vacuum, and look for the conditions which allow for a stringent noninterferometric test of spontaneous collapse models. In particular we compare different possible techniques to detect the particle motion. Key conditions which need to be achieved are extremely low residual pressure and the ability to detect the particle at ultralow power. We compare three different detection approaches based respectively on a optical cavity, optical tweezer and a electrical readout, and for each one we assess advantages, drawbacks and technical challenges

Evaluation of noninvasive cardiac output methods during exercise

Noninvasive techniques to estimate cardiac output (Qc) will be used during future space flight. This retrospective literature survey compared the Qc techniques of carbon dioxide rebreathing (CO2-R), CO2 single breath (CO2-S), Doppler (DOP), impedance (IM), and inert gas (IG: acetylene or nitrous oxide) to direct (DIR) assessments measured at rest and during exercise

WHO Takes Action to Promote the Health of Refugees and Migrants

Migration is a defining issue of our time, with 1 billion migrants globally, of whom 258 million have crossed borders. Climate change and political instability propel ever-greater displacement, with major detriments to health. Policies that fail to prevent human trafficking or guarantee essential services undermine Universal Health Coverage (UHC) and the global pledge to “leave no one behind.” The World Health Assembly should robustly implement WHO’s Global Action Plan (GAP) on the Health of Refugees and Migrants.ugees and Migrants

Power Emission Enhancement of Light Emitting Diode by Using InN based Quantum Dot

AbstractThis paper highlights the enhancement of emitted power from light emitting diodes using InN based quantum dot in the active layer of the device structure. We have developed mathematical models and analyzed numerically the temperature dependence of the degradation rate of the device lifetime, the effect of light transmission factor and the operating time on the power emitted from the light emitting diodes. The results obtained by using InN based quantum dot in the active layer of the device have been compared with those obtained by using InP based quantum dot in the active layer of the device. The comparison results reveal that the degradation rate of the device has been reduced and the power emission has been enhanced significantly by using InN based quantum dot in the active layer of the device. It can be then concluded that InN based quantun dot will bring a revolusionary changes in the performance improvement of LEDs in the near future

Properties of the Discrete Hilbert Transform

The asymptotic behavior of the distribution function of the Hilbert transform of sequences from the class l1 is studied. The concept of Q-summability of series is introduced; using this notion, it is shown that the Hilbert transform of a sequence from the class l1 is Q-summable and is Q-sum is zero