Recording of natural head position using stereophotogrammetry: A new technique and reliability study

The purpose of this study was to develop a technique to record physical references and orient digital mesh models to natural head position (NHP) using stereo-photogrammetry (SP). The first step was to record the digital mesh model of a hanging reference board placed at the capturing position of the SP machine. The board was aligned to the true vertical using a plumb bob. It was also aligned with laser plane parallel to the hanging mirror which was located at the center of the machine. Parameter derived from the digital mesh model of the board was then used to adjust the roll, pitch and yaw of the subsequent captures of subjects. This information was valid until the next machine calibration. The board placement was repeatable with standard deviation of less than 0.1 degrees for both pitch and yaw; 0.15 degrees for roll angles.postprin

Cerebrospinal fluid to serum glucose ratio in non-hypoglycorrhachic neurological conditions

Objective. To explore the relevance of cerebrospinal fluid to serum glucose ratio in non-hypoglycorrhachic conditions. Design. Retrospective observational study. Setting. Neurology ward, university teaching hospital, Hong Kong. Patients. Adult patients with conditions unrelated to hypoglycorrhachia who underwent lumbar puncture. Main outcome measures. Cerebrospinal fluid and simultaneous serum glucose concentrations, and their ratio to each other. Results. Between September 1998 and August 2003, 170 cerebrospinal fluid and serum glucose samples were collected from 138 patients. Mean cerebrospinal fluid to serum glucose ratio was 0.61 (standard deviation, 0.142; range, 0.21-1.00). With the exception of cerebrospinal fluid protein level, laboratory parameters were similar among different diseases. The glucose ratio was lower than 0.6 in 43% and lower than 0.5 in 19% of samples. Cases with a low glucose ratio appeared to have higher serum glucose concentrations (significant among groups with different glucose ratios, P<0.001). The mean glucose ratio (0.65) was also significantly higher in patients with serum glucose concentration of lower than 7.8 mmol/L compared with those with serum glucose concentration between 7.8 and 11.1 mmol/L (mean, 0.46), or higher than 11.1 mmol/L (mean, 0.46) [P<0.001]. There was a strong negative correlation between the glucose ratio and serum glucose concentration (r= -0.704, P<0.001). Conclusion. A lowered cerebrospinal fluid to serum glucose ratio is often seen in the absence of an appropriate disorder, especially when simultaneous serum glucose concentration is elevated. This may be explained by the saturation kinetics of glucose transportation in hyperglycaemia, and the time lag for cerebrospinal fluid and glucose to equilibrate when the blood level fluctuates.published_or_final_versio

An epidemiological study of motor neuron disease in Hong Kong

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Clinical relevance of severe initial hypertension in acute intracerebral haemorrhage

Free Paper Presentations – Session 2OBJECTIVE: To characterise severe initial hypertension (SIH) in the acute intracerebral haemorrhage (ICH) and the related clinical outcomes. METHODOLOGY: We prospectively identified patients admitted to a regional hospital with acute ICH between January 2003 and September 2003. SIH was defined by systolic BP >180 mmHg, diastolic BP >105 mmHg and/or mean BP >130 mmHg for 2 or more readings at 10 or more minutes apart. Clinical data was recorded and analyzed. The modified Rankin score was used to assess disability. RESULTS: A total of 102 patients were identified. SIH was found in 72 patients (70.6%). Comparing those with SIH and those without SIH, they differed statistically in Glasgow Coma Scale (p=0.03), National Institutes of Health Stroke Scale (p<0.001), volume of ICH (p=0.006), past history of hypertension (p=0.03) and time from onset to hospital arrival (p=0.013). Patients with SIH had a statistically significant increase in 30-day mortality (p=0.028) and 3-month mortality (p=0.016) as well as increase in 30-day disability (p=0.003) and 3-month disability (p=0.006). However, the correlation between SIH and mortality or disability was lost when controlling for the above factors. Furthermore, about half of the patients with SIH had their BP subsided within the first day, and this was associated with a significantly lower 30-day disability (p=0.033) and 3-month disability (p=0.045). CONCLUSION: SIH in acute ICH is related to a poor neurological state, an increased volume of ICH, a past history of hypertension and a shorter delay from onset. SIH is a prognostic indicator for mortality and disability but is not an independent factor. As those with early settle of BP have a lower disability, aggressive BP control in the acute phase of ICH may lessen the morbidity.published_or_final_versio

Predictive factors for ischemic strokes complicating tuberculous meningitis

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Headache co-morbidity and seizure control in patients with epilepsy

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Seronegative myasthenia gravis in Hong Kong Chinese

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Split Supersymmetry from Anomalous U(1)

We present a scenario wherein the anomalous U(1) D-term of string origin triggers supersymmetry breaking and generates naturally a Split Supersymmetry spectrum. When the gaugino and the Higgsino masses (which are of the same order of magnitude) are set at the TeV scale, we find the scalar masses to be in the range (10^6 - 10^8) GeV. The U(1) D-term provides a small expansion parameter which we use to explain the mass and mixing hierarchies of quarks and leptons. Explicit models utilizing exact results of N = 1 suersymmetric gauge theories consistent with anomaly constraints, fermion mass hierarchy, and supersymmetry breaking are presented.Comment: 20 pages in LaTeX, version published in NPH

Natural course of patients with acute myelitis

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On graviton non-Gaussianities during inflation

We consider the most general three point function for gravitational waves produced during a period of exactly de Sitter expansion. The de Sitter isometries constrain the possible shapes to only three: two preserving parity and one violating parity. These isometries imply that these correlation functions should be conformal invariant. One of the shapes is produced by the ordinary gravity action. The other shape is produced by a higher derivative correction and could be as large as the gravity contribution. The parity violating shape does not contribute to the bispectrum [1106.3228, 1108.0175], even though it is present in the wavefunction. We also introduce a spinor helicity formalism to describe de Sitter gravitational waves with circular polarization. These results also apply to correlation functions in Anti-de Sitter space. They also describe the general form of stress tensor correlation functions, in momentum space, in a three dimensional conformal field theory. Here all three shapes can arise, including the parity violating one.Comment: 51 pages, v2: Corrected statement about parity violation in the gravitational wave bispectrum. Some other changes and references adde