Filamentation of a relativistic proton bunch in plasma.

We show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma skin depth for the instability to occur. At the threshold, the outcome of the experiment alternates between filamentation and self-modulation instability (evidenced by longitudinal modulation into microbunches).

Hosing of a Long Relativistic Particle Bunch in Plasma.

Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, self-modulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge.

Morphologic criteria of vermiform appendix on computed tomography and a possible risk of developing acute appendicitis.

Objective: To evaluate the correlation of morphological criteria of the cecal appendix using computed tomography (CT) and the possible risk of developing acute appendicitis.

Materials And Methods: Cases were defined as patients with surgically confirmed acute appendicitis who had undergone CT at least twice: at diagnosis and at least one month prior. Controls were defined as emergency patients with abdominal pain who had undergone abdominal CT that excluded acute appendicitis and had also undergone CT at least one month before.