p31 comet acts to ensure timely spindle checkpoint silencing subsequent to kinetochore attachment

The spindle assembly checkpoint links the onset of anaphase to completion of chromosome-microtubule attachment and is mediated by the binding of Mad and Bub proteins to kinetochores of unattached or maloriented chromosomes. Mad2 and BubR1 traffic between kinetochores and the cytosol, thereby transmitting a "wait anaphase" signal to the anaphase-promoting complex. It is generally assumed that this signal dissipates automatically upon kinetochore-microtubule binding, but it has been shown that under conditions of nocodazole-induced arrest p31comet, a Mad2-binding protein, is required for mitotic progression. In this article we investigate the localization and function of p31 comet during normal, unperturbed mitosis in human and marsupial cells. We find that, like Mad2, p31 comet traffics on and off kinetochores and is also present in the cytosol. Cells depleted of p31 comet arrest in metaphase with mature bipolar kinetochore-microtubule attachments, a satisfied checkpoint, and high cyclin B levels. Thus p31 comet is required for timely mitotic exit. We propose that p31 comet is an essential component of the machinery that silences the checkpoint during each cell cycle

A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments

We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an integration of the data at fixed Q**2 over the whole significant x-interval. From these data we extracted the structure function F2 and, by including other world data, we studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and demand significant improvements in theoretical predictions for a meaningful comparison with new experimental results.Comment: revtex4 18 pp., 12 figure

Lasery paskowe typu zygzak pompowane diodami

We have considered the advantages of diode pumping of solid-state lasers with high-performance active medium. The article describes the design features of solid-state zigzag lasers based on a flat truncated prism. We have identified the range of the angles under which zigzag laser with small output beam transverse size can be obtained that significantly increases the output power density. It was shown that the diode pumping system well combines with the zigzag geometry of the solid laser based on the flat truncated prism.Rozważono zalety laserów półprzewodnikowych o wysokosprawnym ośrodku aktywnym, pompowanych diodami. Artykuł opisuje cechy konstrukcyjne laserów na ciele stałym typu zygzak w formie płaskiego graniastosłupa ściętego. Zidentyfikowaliśmy zakres kątów, w których może być otrzymany laser typu zygzak o małym przekroju poprzecznym wiązki wyjściowej, co znacznie zwiększa gęstość mocy wyjściowej. Wykazaliśmy, że diodowy system pompowania dobrze łączy się z laserem typu zygzak w formie płaskiego graniastosłupa ściętego

Analiza strat energii w laserach paskowych typu zygzak

Artykuł poświęcony stratom energii w laserze z rezonatorem Fabry-Perota i typu zygzak w formie płaskiego graniastosłupa ściętego. Zawiera on skorygowane wartości strat dla lasera typu zygzak z rezonatorem zawierającym trzy zwierciadła. Oprócz materiałowych strat na absorpcję i rozpraszanie w ośrodku czynnym, uwzględniono również straty spowodowane wyciekiem promieniowania przez nieidealne zwierciadła. Przeanalizowano również zależności współczynnika strat od parametrów projektowych rezonatora lasera zawierającego trzy zwierciadła.The article considers energy losses in a Fabry-Perot laser resonator and zigzag laser in form of a flat truncated prism. It refines the values of the harmful losses of the zigzag laser three-mirror optical resonator, in which apart from material losses on absorption and scattering in the matrix of the active media, the losses on the radiation transferring through the non-ideal reflecting mirrors that provide a zigzag course of the beam in the cavity are included. The dependences of the losses coefficient on the design parameters of the three-mirror zigzag laser resonator are also analyzed

Proton source size measurements in the eA → e'ppX reaction

Two-proton correlations at small relative momentum q were studied in the e A ( 3 H e , 4 H e , C , F e ) → e ′ p p X reaction at E 0 = 4.46     G e V using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in e A reactions for the first time