DAVIS: A direct algorithm for velocity-map imaging system.

In this work, we report a direct (non-iterative) algorithm to reconstruct the three-dimensional (3D) momentum-space picture of any charged particles collected with a velocity-map imaging system from the two-dimensional (2D) projected image captured by a position-sensitive detector. The method consists of fitting the measured image with the 2D projection of a model 3D velocity distribution defined by the physics of the light-matter interaction. The meaningful angle-correlated information is first extracted from the raw data by expanding the image with a complete set of Legendre polynomials. Both the particle's angular and energy distributions are then directly retrieved from the expansion coefficients. The algorithm is simple, easy to implement, fast, and explicitly takes into account the pixelization effect in the measurement.

Systematic review of the effects of aromatase inhibitors on pain associated with endometriosis.

OBJECTIVE: To assess the effects of aromatase inhibitors in women symptomatic of pain with endometriosis. DESIGN: A systematic review of published literature. MATERIAL AND METHODS: We conducted a comprehensive literature search to identify all the published observational and randomised studies evaluating the efficacy of aromatase inhibitors on pain associated with endometriosis. A combination of keywords was used to identify the maximum number of relevant citations in MEDLINE, EMBASE, CINAHL and the Cochrane Database. Outcome Pain relief, lesion size and quality of life. RESULTS: There were eight studies (137 women) evaluating outcomes of aromatase inhibitors. In case series/reports (seven studies, 40 women), aromatase inhibitors combined with progestogens or oral contraceptive pill or gonadotrophin-releasing hormone (GnRH) analogues reduced mean pain scores and lesion size and improved quality of life. An RCT (97 women) demonstrated that aromatase inhibitors in combination with GnRH analogues significantly improved pain (P < 0.0001) compared with GnRH analogues alone together with significant improvement in multidimensional patient scores (P < 0.0001). There was no significant reduction in spine or hip-bone densities. CONCLUSION: Aromatase inhibitors appear to have a promising effect on pain associated with endometriosis, but the strength of this inference is limited due to a dearth of the evidence available.

Real-time breath monitoring of propofol and its volatile metabolites during surgery using a novel mass spectrometric technique: a feasibility study.

BACKGROUND: At present, there is no rapid method for determining the plasma concentration of i.v. anaesthetics. A solution might be the measurement of the anaesthetic concentration in expired breath and its relation to the plasma concentration. We used chemical ionization methods to determine whether an i.v. anaesthetic can be detected in the low concentrations (parts per billion by volume) in the expired breath of an anaesthetized patient. METHOD: Chemical ionization mass spectrometry can measure trace gases in air with high sensitivity without interference from major gases. We carried out a feasibility trial with a proton transfer reaction mass spectrometer (PTR-MS) to monitor the i.v. anaesthetic agent propofol and two of its metabolites in exhaled gas from an anaesthetic circuit. Exhaled gas was sampled via a 4 m long, unheated tube connected to the PTR-MS. RESULTS: Propofol and its metabolites were monitored in real time in the expired breath of patients undergoing surgery. CONCLUSION: Routine measurement of i.v. agents, analogous to that for volatile anaesthetic agents, may be possible.

The effect of posture on cerebral oxygenation during abdominal surgery.

Performing surgery with a patient in the head-down position for several hours may cause marked facial and conjunctival oedema. It is not known whether oedema might also be occurring within the cranial cavity. This study, using near-infrared regional cerebral oximetry, was performed to see if there was any evidence of cerebral anoxia during operations performed with patients in the head-down position compared with those performed on patients who were flat. Patients managed in the head-down position did not demonstrate any reduction in regional cerebral oxygenation, but those who were managed flat did. An explanation of these paradoxical findings is elusive.

The contamination of volatile anaesthetics in an in-circle vaporizer with water during prolonged closed-circle anaesthesia.

The amount of water present in sevoflurane in an in-circle vaporizer after long procedures was measured. This demonstrated that the sevoflurane residue was contaminated with a small amount of water.

The use of epidural ropivacaine in high doses for the management of pain from invasive carcinoma of the cervix.

A case is presented of a young woman with advanced cervical cancer invading the rectum and sacral nerves giving rise to an intractable pain state. The management of her symptoms using a domicillary infusion of diamorphine with high doses of ropivacaine is described. It is believed that this is the first presentation of ropivacaine being used in daily doses approaching 2 g, and the associated problems are discussed.

Topographical anatomy of the lumbar epidural region: an in vivo study using computerized axial tomography.

The lumbar epidural region was studied using computerized tomography. This technique allows examination of the region in vivo. It confirmed that the spinal canal is oval in the upper lumbar region, becoming triangular lower down, and that the ligamenta flava form a posterior recess to the vertebral canal. Epidural fat is confined to this region between the ligamenta flava and the intervertebral foramina, and the dura mater lies apposed to the walls of the vertebral canal except where there is epidural fat. The absence of a posterior midline fold of dura mater was noted, and discussed in the light of other studies.

Chiropractic biophysics technique: a linear algebra approach to posture in chiropractic.

OBJECTIVE: This paper discusses linear algebra as applied to human posture in chiropractic, specifically chiropractic biophysics technique (CBP). MATHEMATICAL ANALYSIS: Rotations, reflections and translations are geometric functions studied in vector spaces in linear algebra. These mathematical functions are termed rigid body transformations and are applied to segmental spinal movement in the literature. Review of the literature indicates that these linear algebra concepts have been used to describe vertebral motion. However, these rigid body movers are presented here as applying to the global postural movements of the head, thoracic cage and pelvis. CONCLUSION: The unique inverse functions of rotations, reflections and translations provide a theoretical basis for making postural corrections in neutral static resting posture. Chiropractic biophysics technique (CBP) uses these concepts in examination procedures, manual spinal manipulation, instrument assisted spinal manipulation, postural exercises, extension traction and clinical outcome measures.

A model of the extradural space and a reappraisal of the extradural space pressure.

A model is described which was used to study the genesis of the pressure in the extradural space. It consists of a Perspex outer tube, with perforations covered with rubber septa to allow the insertion of needles, and Paul's tubing on the inside, representing the dura mater. The Paul's tubing is filled with water through a constant head of pressure apparatus. The response of the model to the insertion of an extradural needle and the reproduction of various clinical phenomena are described. The pressure in the extradural space is discussed in relation to the performance of the model.