Large-scale educational telecommunications systems for the US: An analysis of educational needs and technological opportunities

The needs to be served, the subsectors in which the system might be used, the technology employed, and the prospects for future utilization of an educational telecommunications delivery system are described and analyzed. Educational subsectors are analyzed with emphasis on the current status and trends within each subsector. Issues which affect future development, and prospects for future use of media, technology, and large-scale electronic delivery within each subsector are included. Information on technology utilization is presented. Educational telecommunications services are identified and grouped into categories: public television and radio, instructional television, computer aided instruction, computer resource sharing, and information resource sharing. Technology based services, their current utilization, and factors which affect future development are stressed. The role of communications satellites in providing these services is discussed. Efforts to analyze and estimate future utilization of large-scale educational telecommunications are summarized. Factors which affect future utilization are identified. Conclusions are presented

The influence of phase-modulation on femtosecond time-resolved coherent Raman spectroscopy

The influence of phase-modulation on femtosecond time-resolved coherent Raman scattering is investigated theoretically and experimentally. The coherent Raman signal taken as a function of the spectral position shows unexpected temporal oscillations close to time zero. A theoretical analysis of the coherent Raman scattering process indicates that the femtosecond light pulses are amplitude and phase modulated. The pulses are asymmetric in time with more slowly decaying trailing wings. The phase of the pulse amplitude contains quadratic and higher-order contributions

Finding Fault?: Exploring Legal Duties to Return Incidental Findings in Genomic Research

The use of whole genome sequencing in biomedical research is expected to produce dramatic advances in human health. The increasing use of this powerful, data-rich new technology in research, however, will inevitably give rise to incidental findings (IFs), findings with individual health or reproductive significance that are beyond the aims of the particular research, and the related questions of whether and to what extent researchers have an ethical obligation to return IFs. Many have concluded that researchers have an ethical obligation to return some findings in some circumstances, but have provided vague or context-dependent approaches to determining which IFs must be returned and when. As a result, researchers have started returning IFs inconsistently, giving rise to concerns about legal liability in circumstances in which notification could have potentially prevented injury. While it is clear that ethical guidance should not be automatically codified as the law, and that crafting ethical obligations around legal duties can be inappropriate, the ethical debate should not proceed unaware of the potential legal ramifications of advancing and implementing an ethical obligation to return IFs. This article is the first to assess the legal claims that could be brought for a researcher’s failure to return IFs. The potential for researchers to be held liable in tort is still uncertain and turns largely on a number of factors — including customary practice and guidance documents — that are still in flux. Unlike medical care, which has a well-defined duty into which evolving scientific knowledge about genetics and genomics can readily be incorporated, a researcher’s duty to return IFs is less well defined, making it difficult to determine at the outset whether and when legal liability will attach. This article advocates for a clearer, ethically sound standard of requiring that researchers disclose in the informed consent document which approach to offering IFs will be taken. This approach enables participants to know at the outset which findings will be returned, allows researchers to ascertain when their failure to appropriately return incidental findings will give rise to liability, and enables courts to make determinations that will produce consistent legal guidance

A gene regulatory network armature for T lymphocyte specification

Choice of a T lymphoid fate by hematopoietic progenitor cells depends on sustained Notch–Delta signaling combined with tightly regulated activities of multiple transcription factors. To dissect the regulatory network connections that mediate this process, we have used high-resolution analysis of regulatory gene expression trajectories from the beginning to the end of specification, tests of the short-term Notch dependence of these gene expression changes, and analyses of the effects of overexpression of two essential transcription factors, namely PU.1 and GATA-3. Quantitative expression measurements of >50 transcription factor and marker genes have been used to derive the principal components of regulatory change through which T cell precursors progress from primitive multipotency to T lineage commitment. Our analyses reveal separate contributions of Notch signaling, GATA-3 activity, and down-regulation of PU.1. Using BioTapestry (www.BioTapestry.org), the results have been assembled into a draft gene regulatory network for the specification of T cell precursors and the choice of T as opposed to myeloid/dendritic or mast-cell fates. This network also accommodates effects of E proteins and mutual repression circuits of Gfi1 against Egr-2 and of TCF-1 against PU.1 as proposed elsewhere, but requires additional functions that remain unidentified. Distinctive features of this network structure include the intense dose dependence of GATA-3 effects, the gene-specific modulation of PU.1 activity based on Notch activity, the lack of direct opposition between PU.1 and GATA-3, and the need for a distinct, late-acting repressive function or functions to extinguish stem and progenitor-derived regulatory gene expression

Regulated expression and function of CD122 (interleukin-2/interleukin-15R-β) during lymphoid development

To determine whether signaling via CD122 (interleukin-2 [IL-2]/IL-15 receptor β-chain) plays a role in regulating the expansion and differentiation of lymphocyte precursors, we have characterized its expression and evaluated its ability to influence the activity of developing lymphoid cells. A significant fraction of Sca1^+Lin^- hematopoietic stem cells in day 12 fetal liver were found to be CD122^+. CD122-mRNA^+ and IL-2-mRNA^+ cells were also localized in embryo sections within pharyngeal blood vessels adjacent to and surrounding the thymic analgen. This distribution is consistent with the migration of CD122^+ progenitor cells from the liver to the developing thymus where a majority of Sca1^+ intrathymic T-cell progenitors were CD122^+. Analysis of CD122 expression in the day 12 fetal liver revealed that the majority of B220^+ cells were CD122^+. Furthermore, CD122 expression was restricted to the earliest B220^+ cells (CD43^+CD24^-; prepro B cells; fraction A) that proliferate vigorously to IL-2 in the absence of any stromal cells, but not to IL-15. Consistent with a role for the IL-2/IL- 2R pathway in lymphocyte development is the progressive loss of B cells seen in IL-2-deficient mice. Together, these observations suggest that CD122 plays a role in regulating normal lymphocyte development in vivo

Multiple scattering of photons by atomic hyperfine multiplets

Mesoscopic interference effects in multiple scattering of photons depend crucially on the internal structure of the scatterers. In the present article, we develop the analytical theory of multiple photon scattering by cold atoms with arbitrary internal hyperfine multiplets. For a specific application, we calculate the enhancement factor of elastic coherent backscattering as a function of detuning from an entire hyperfine multiplet of neighboring resonances that cannot be considered isolated. Our theory permits to understand why atoms behave differently from classical Rayleigh point-dipole scatterers, and how the classical description is recovered for larger but still microscopic objects like molecules or clusters.Comment: minor changes, published versio

High proton conductivity in cyanide-bridged metal-organic frameworks: understanding the role of water

We investigate and discuss the proton conductivity properties of the cyanide-bridged metal–organic framework (MOF) [Nd(mpca)2Nd(H2O)6Mo(CN)8]·nH2O (where mpca is 5-methyl-2-pyrazinecarboxylate). This MOF is one of an exciting class of cyanide-bridged materials that can combine porosity with magnetism, luminescence, and proton conductivity. Specifically, we show that this material features highly hydrophilic open channels filled with water molecules. They enable a high proton conductivity, as much as 10−3 S cm−1. A rich hydrogen-bonding network, formed by the ligands' carboxylate groups with both coordinated and lattice water molecules, facilitates this high proton conductivity. Combined thermogravimetric studies, FTIR spectroscopy and PXRD analysis show that upon heating at 80 °C, the lattice water molecules are removed without any change in the framework. Further heating at 130 °C results in a partial removal of the coordinated water molecules, while still retaining the original framework. These activated MOFs shows an increasing conductivity from ∼10−9 S cm−1 to ∼10−3 S cm−1 when the relative humidity increases from 0% to 98%. Our studies show that the increase in proton conductivity is correlated with the re-hydration of the framework with lattice water molecules. The Arrhenius activation energy for the proton conductivity process is low (Ea = 37 kJ mol−1), indicating that the protons “hop” through the channels following the Grotthuss mechanism. The fact that this MOF is remarkably stable both under high humidity conditions and at relatively high temperatures (up to 130 °C) makes it a good candidate for real-life applications