Role of Vector Mesons in High-Q^2 Lepton-Nucleon Scattering

The possible role played by vector mesons in inclusive deep inelastic lepton-nucleon scattering is investigated. In the context of the convolution model, we calculate self-consistently the scaling contribution to the nucleon structure function using the formalism of time-ordered perturbation theory in the infinite momentum frame. Our results indicate potentially significant effects only when the vector meson---nucleon form factor is very hard. Agreement with the experimental antiquark distributions, however, requires relatively soft form factors for the $\pi N$, $\rho N$ and $\omega N$ vertices.Comment: 22 pages, 9 figures (available upon request); accepted for publication in Phys.Rev.D, ADP-92-197/T12

An Outbreak of Rift Valley Fever in Northeastern Kenya, 1997-98

In December 1997, 170 hemorrhagic fever-associated deaths were reported in Carissa District, Kenya. Laboratory testing identified evidence of acute Rift Valley fever virus (RVFV). Of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-RVFV immunoglobulin (Ig) M positive. An age-adjusted IgM antibody prevalence of 14% was estimated for the district. We estimate approximately 27,500 infections occurred in Garissa District, making this the largest recorded outbreak of RVFV in East Africa. In multivariate analysis, contact with sheep body fluids and sheltering livestock in one’s home were significantly associated with infection. Direct contact with animals, particularly contact with sheep body fluids, was the most important modifiable risk factor for RVFV infection. Public education during epizootics may reduce human illness and deaths associated with future outbreaks

η′\eta^{\prime} production in proton-proton scattering close to threshold}

The $pp \to pp \eta^{\prime}$ (958) reaction has been measured at COSY using the internal beam and the COSY-11 facility. The total cross sections at the four different excess energies \mbox{$Q = ~1.5 ~MeV, ~1.7 ~MeV, ~2.9 ~MeV,$ and $~4.1 MeV$} have been evaluated to be \mbox{$\sigma = 2.5 \pm 0.5~nb$, $~~~ 2.9 \pm 1.1~nb$, $~~~ 12.7 \pm 3.2~nb$, ~ and $~~~ 25.2 \pm 3.6 ~nb$}, respectively. In this region of excess energy the $\eta^{\prime}$ (958) cross sections are much lower compared to those of the $\pi ^0$ and $\eta$ production.Comment: 11 pages, 3 figure

Optics and Quantum Electronics

Contains table of contents for Section 3 and reports on eighteen research projects.Defense Advanced Research Projects Agency/MIT Lincoln Laboratory Contract MDA972-92-J-1038Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Grant ECS 94-23737U.S. Air Force - Office of Scientific Research Contract F49620-95-1-0221U.S. Navy - Office of Naval Research Grant N00014-95-1-0715MIT Center for Material Science and EngineeringNational Center for Integrated Photonics Technology Contract DMR 94-00334National Center for Integrated Photonics TechnologyU.S. Navy - Office of Naval Research (MFEL) Contract N00014-94-1-0717National Institutes of Health Grant 9-R01-EY11289MIT Lincoln Laboratory Contract BX-5098Electric Power Research Institute Contract RP3170-25ENEC

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points