Sudden Flight and True Sudden Stops

We extend the sudden stops literature by allowing crisis episodes to be caused by either the retreat of global investors, as is assumed but not shown in the extant literature, or the sudden flight of local investors. We find that almost half of the previously defined sudden stops are actually episodes of sudden flight. Compared to sudden flight, true sudden stops are bunched and are associated with greater slowdowns in economic activity and sharper currency depreciations. We show that the empirical regularities of sudden flight and true sudden stops are consistent with theoretical models that incorporate gross capital flows and information asymmetries.international capital flows, capital flight, emerging market crises

Spontaneous Raman scattering as a high resolution XUV radiation source

A type of high resolution XUV radiation source is described which is based upon spontaneous anti-Stokes scattering of tunable incident laser radiation from atoms excited to metastable levels. The theory of the source is summarized and two sets of experiments using He (1s2s)(1)S atoms, produced in a cw hollow cathode and in a pulsed high power microwave discharge, are discussed. The radiation source is used to examine transitions originating from the 3p(6) shell of potassium. The observed features include four previously unreported absorption lines and several sharp interferences of closely spaced autoionizing lines. A source linewidth of about 1.9 cm(-1) at 185,000 cm(-1) is demonstrated

GRBs from unstable Poynting dominated outflows

Poynting flux driven outflows from magnetized rotators are a plausible explanation for gamma-ray burst engines. We suggest a new possibility for how such outflows might transfer energy into radiating particles. We argue that the Poynting flux drives non-linearly unstable large amplitude electromagnetic waves (LAEMW) which ``break'' at radii $r_t \sim 10^{14}$ cm where the MHD approximation becomes inapplicable. In the ``foaming'' (relativisticly reconnecting) regions formed during the wave breaks the random electric fields stochastically accelerate particles to ultrarelativistic energies which then radiate in turbulent electromagnetic fields. The typical energy of the emitted photons is a fraction of the fundamental Compton energy $\epsilon \sim f \hbar c/r_e$ with $f \sim 10^{-3}$ plus additional boosting due to the bulk motion of the medium. The emission properties are similar to synchrotron radiation, with a typical cooling time $\sim 10^{-4}$ sec. During the wave break, the plasma is also bulk accelerated in the outward radial direction and at larger radii can produce afterglows due to the interactions with external medium. The near equipartition fields required by afterglow models maybe due to magnetic field regeneration in the outflowing plasma (similarly to the field generation by LAEMW of laser-plasma interactions) and mixing with the upstream plasma.Comment: 15 pages, 1 figur

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

Whose Duty is it Anyway?: the Kennedy Krieger Opinion and its Implications for Public Health Research

In this article, the authors discuss the Maryland Court of Appeals decision in the case of Grimes v. Kennedy Krieger Institute, Inc. and its implications for the tort duty owed by researchers, in particular public health researchers, to their subjects. The Opinion resulted from two lawsuits alleging lead poisoning of children enrolled in a study conducted by the Kennedy Krieger Institute, a world renown pediatric research and treatment facility. The opinion shocked the research establishment with its scathing characterization of researchers and its apparent holding that in Maryland a parent cannot consent to the participation of a child in nontherapeutic research or other studies in which there is any risk of injury or damage to the health of the subject. While this was the focus of much of the research community, the issue in dispute in the case was that of the scope of duty of the researchers. Hoffmann and Rothenberg describe the facts leading to the case, many of which were omitted from the Court of Appeals decision which resulted from an appeal to a motion for summary judgment, and then discuss two possible interpretations of the Court\u27s decision as it relates to the duty of researchers. One interpretation is based on a broad view of what constitutes the research endeavor and its associated risks and would arguably not result in a change in the legal duties of researchers. The other is based on a narrow view of the research project and would lead to the disclosure of risks not traditionally required by law as they fall outside of risks resulting from participation in the research protocol. The authors assert that as a result of confusion in the Opinion regarding the definition of the research study, the Court\u27s decision may result in a significantly broader duty than has been posed historically in the research setting. In addition to exploring the contrasting interpretations of the Court\u27s Opinion, the authors deconstruct the scope of the duty as articulated by the Court and pose a series of questions as to how such a duty might be discharged and how realistic the Court\u27s apparent expectations are regarding the duty or researchers. Finally, they discuss the implications of the Court\u27s apparent broad based duty requirement in the context of public health studies and raise the question whether the Opinion may ultimately have negative consequences for the future of public health research in Maryland and for the compensation of injured research subjects

Ikaros represses and activates PU.1 cell-type-specifically through the multifunctional Sfpi1 URE and a myeloid specific enhancer

Generation of myeloid and lymphoid cells from progenitors involves dynamic changes in transcription factor expression and use, and disruption of hematopoietic transcription factor function and expression can contribute to leukemic transformation. PU.1 and Ikaros are pivotal factors whose expression and utilization are dynamically altered during hematopoietic development. Here, we demonstrate that expression of PU.1, encoded by the Sfpi1 gene, is divergently regulated by Ikaros in distinct cell type-specific contexts. Chromatin immune precipitation analysis and functional perturbations revealed that Ikaros can directly repress or activate Sfpi1 transcription via different PU.1 cis-elements, with PU.1 and Ikaros collaborating at myeloid-specific elements but not at other elements. Our results thus shed light on how PU.1 and Ikaros can act as lineage competency factors to facilitate both myeloid and lymphoid developmental programs

Lyt-2 glycoprotein is synthesized as a single molecular species

We investigated the possibility that the Lyt-2 molecules made by uncloned mouse T lymphocytes would show variable primary structures like those of immunoglobulins. Newly synthesized Lyt-2/3 complexes were found to include only two major components, both discrete glycoproteins with apparent molecular weights of 31,000 (31 K) and 35,000 (35 K). When products of Lyt-2.1 and Lyt-2.2 thymocytes were compared by two-dimensional nonequilibrium pH gradient electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis, the isoelectric points of the 35 K molecules were different; thus, the 35 K component was likely to be encoded by the Lyt-2 locus itself. However, the 35 K molecules made by any one genotype were homogeneous in charge as well as in size. The homogeneity was obscured rapidly by post-translational modification. Most strikingly, within 30 min of initial synthesis, these processing events generated the conspicuous array of microheterogeneous products that form the "38 K" component of cell-surface Lyt-2/3