29 research outputs found
Quantum capacity of an amplitude-damping channel with memory
We calculate the quantum capacity of an amplitude-damping channel with time
correlated Markov noise, for two channel uses. Our results show that memory of
the channel increases it's ability to transmit quantum information
significantly. We analyze and compare our findings with earlier numerical
results on amplitude-damping channel with memory. An upper bound on the amount
of quantum information transmitted over the channel in presence of memory, for
an arbitrary number of channel uses is also presented.Comment: 17 Pages, 5 Figure
Delamination technique together with longitudinal incisions for treatment of Chiari I/syringomyelia complex: a prospective clinical study
<p>Abstract</p> <p>Background</p> <p>Treatment modalities in Chiari malformation type 1(CMI) accompanied by syringomyelia have not yet been standardized. Pathologies such as a small posterior fossa and thickened dura mater have been discussed previously. Various techniques have been explored to enlarge the foramen magnum and to expand the dura. The aim of this clinical study was to explore a new technique of excision of the external dura accompanied by widening the cisterna magna and making longitudinal incisions in the internal dura, without disturbing the arachnoid.</p> <p>Methods</p> <p>Ten patients with CMI and syringomyelia, operated between 2004 and 2006, formed this prospective series. All cases underwent foramen magnum decompression of 3 × 3 cm area with C1–C2 (partial) laminectomy, resection of foramen magnum fibrous band, excision of external dura, delamination and widening of internal dura with longitudinal incisions.</p> <p>Results</p> <p>Patients were aged between 25 and 58 years and occipital headache was the most common complaint. The mean duration of preoperative symptoms was 4 years and the follow-up time was 25 months. Clinical progression was halted for all patients; eight patients completely recovered and two reported no change. In one patient, there was a transient cerebrospinal fluid (CSF) fistula that was treated with tissue adhesive. While syringomyelia persisted radiologically with radiological stability in five patients; for three patients the syringomyelic cavity decreased in size, and for the remaining two it regressed completely.</p> <p>Conclusion</p> <p>Removal of the fibrous band and the outer dural layer, at level of foramen magnum, together with the incision of inner dural layer appears to be good technique in adult CMI patients. The advantages are short operation time, no need for duraplasty, sufficient posterior fossa decompression, absence of CSF fistulas as a result of extra arachnoidal surgery, and short duration of hospitalization. Hence this surgical technique has advantages compared to other techniques.</p
Treatment of irritable bowel syndrome with diarrhoea using titrated ondansetron (TRITON): study protocol for a randomised controlled trial
Background: Irritable bowel syndrome with diarrhoea (IBS-D) affects up to 4% of the general population. Symptoms
include frequent, loose, or watery stools with associated urgency, resulting in marked reduction of quality of life and
loss of work productivity. Ondansetron, a 5HT3 receptor antagonist, has had an excellent safety record for over 20 years
as an antiemetic, yet is not widely used in the treatment of IBS-D. It has, however, been shown to slow colonic transit
and in a small randomised, placebo-controlled, cross-over pilot study, benefited patients with IBS-D.
Methods: This trial is a phase III, parallel group, randomised, double-blind, multi-centre, placebo-controlled trial, with
embedded mechanistic studies. Participants (n = 400) meeting Rome IV criteria for IBS-D will be recruited from
outpatient and primary care clinics and by social media to receive either ondansetron (dose titrated up to 24 mg daily)
or placebo for 12 weeks. Throughout the trial, participants will record their worst abdominal pain, worst urgency, stool
frequency, and stool consistency on a daily basis.
The primary endpoint is the proportion of “responders” in each group, using Food and Drug Administration (FDA)
recommendations. Secondary endpoints include pain intensity, stool consistency, frequency, and urgency. Mood and
quality of life will also be assessed.
Mechanistic assessments will include whole gut transit, faecal tryptase and faecal bile acid concentrations at baseline
and between weeks 8 and 11. A subgroup of participants will also undergo assessment of sensitivity (n = 80) using the
barostat, and/or high-resolution colonic manometry (n = 40) to assess motor patterns in the left colon and the impact
of ondansetron.
Discussion: The TRITON trial aims to assess the effect of ondansetron across multiple centres. By defining
ondansetron’s mechanisms of action we hope to better identify patients with IBS-D who are likely to respond