A room-temperature ion trapping apparatus with hydrogen partial pressure below 10-11 mbar.

The lifetime of trapped ion ensembles corresponds to a crucial parameter determining the potential scalability of their prospective applications and is often limited by the achievable vacuum level in the apparatus. We report on the realization of a room-temperature 40Ca+ ion trapping vacuum apparatus with unprecedentedly low reaction rates of ions with a dominant vacuum contaminant: hydrogen. We present our trap assembly procedures and hydrogen pressure characterization by analysis of the CaH+ molecule formation rate.

Calculation of the performance of magnetic lenses with limited machining precision.

To meet a required STEM resolution, the mechanical precision of the pole pieces of a magnetic lens needs to be determined. A tolerancing plugin in the EOD software is used to determine a configuration which both meets the optical specifications and is cost effective under the constraints of current manufacturing technologies together with a suitable combination of correction elements.

Calculation of aberration coefficients by ray tracing.

In this paper we present an approach for the calculation of aberration coefficients using accurate ray tracing. For a given optical system, intersections of a large number of trajectories with a given plane are computed. In the Gaussian image plane the imaging with the selected optical system can be described by paraxial and aberration coefficients (geometric and chromatic) that can be calculated by least-squares fitting of the analytical model on the computed trajectory positions. An advantage of such a way of computing the aberration coefficients is that, in comparison with the aberration integrals and the differential algebra method, it is relatively easy to use and its complexity stays almost constant with the growing complexity of the optical system. This paper shows a tested procedure for choosing proper initial conditions and computing the coefficients of the fifth-order geometrical and third-order, first-degree chromatic aberrations by ray tracing on an example of a weak electrostatic lens. The results are compared with the values for the same lens from a paper Liu [Ultramicroscopy 106 (2006) 220-232].

Seizures and loss of vision in a patient with systemic lupus erythematosus.

Posterior reversible encephalopathy syndrome (PRES) is a rare neurological condition identifiable by clinical presentation and MRI appearance.1 Patients present with headache, seizures, loss of vision and altered mental function. The pathogenesis of the syndrome is poorly understood. One hypothesis is that cerebral vasospasm results in cerebral ischaemia and subsequent development of T2 hyperintensity, and the other is a temporary failure of the autoregulatory capabilities of the cerebral vessels, leading to hyperperfusion, breakdown of the blood-brain barrier, and consequent vasogenic oedema. It is believed that a rapid rise in blood pressure overcomes cerebral autoregulatory mechanisms with abrupt dilatation of cerebral arterioles. We report a patient with systemic lupus erythematosus and PRES after recurrent spontaneous abortion.

Corrections of magnification and focusing in a cathode lens-equipped scanning electron microscope.

One of the well-proven and efficient methods of obtaining a very low-energy impact of primary electrons in the scanning electron microscope is to introduce a retarding field element below the pole piece of the objective lens (OL). It is advantageous to use the specimen alone as the negatively biased electrode (i.e., cathode of the cathode lens). The optical power of the cathode lens modifies some of the standard parameters of the image formation such as relation of working distance to OL excitation or magnification to the scanning coils current, the impact angle of primary electrons, and so forth. In computer-controlled electron microscopes these parameters, particularly with regard to focusing and magnification, can be corrected automatically. Derivation of algorithms for such corrections and their experimental verifications are presented in this paper. Furthermore, a more accurate analytical expression for the focal length of an aperture lens is derived.

A proposed taxonomy for nailfold capillaries based on their morphology.

Certain diseases cause permanent changes to the shapes and densities of nailfold capillaries and, therefore, nailfold capillaroscopy is important as a tool for diagnosing and monitoring these diseases. The first aim of the project is to resolve differences in terminology that have developed over the years in previous work. We propose a taxonomy for nailfold capillaries that cover six descriptive classes: cuticulis, open, tortuous, crossed, bushy, and bizarre. The first three are parametric in that they may be distinguished by the ratio of capillary length to width and by the curvature of the capillary limbs. The last three are characterized by their topology; a crossed capillary has a closed area that is not connected to the image background. Bushy and bizarre capillaries have atypical shapes that are characterized by the convex hull of their skeleton. These descriptive classes may be modified according to anomalies in width and length. The second aim is to automate the classification of capillaries by encapsulating the taxonomy in an algorithm; our computer program rivals the most experienced clinicians in classifying capillaries consistently with an overall agreement of 85% with the clinicians' majority view. This was particularly valuable in classifying borderline shapes objectively and consistently.

Candida colonization in mechanically ventilated patients.

The diagnosis of pulmonary candidosis is controversial. We undertook a prospective study on 50 mechanically ventilated (>48 h) patients who were hospitalized (>72 h) in the intensive care unit (ICU) with the aim of assessing the incidence of the isolation of Candida species from endotracheal aspirates (EA). Patients were categorized as individuals already colonized with Candida spp. on admission, individuals becoming colonized during hospitalization, or patients with no colonization. Patients in the ICU were hospitalized for a mean of 23 days. The percentage of patients already colonized with Candida was low (six of 50; 12%), the incidence of Candida isolation from EA in critically ill, mechanically ventilated patients in ICU was also low (six of 50; 12%). Age, duration of hospitalization, pre-treatment with antimicrobials or immunosuppressive agents and occurrence of underlying disease were not risk factors in our study. Both antifungal usage and neutropenia were more common in already colonized patients. No risk factors were determined for patients colonized during hospitalization. As all the isolates identified were C. albicans. It appears that at present, colonization and/or infection by more resistant Candida species is not a problem in our unit.