Depicting the analyses of the first National Maltese Childhood BMI study

Introduction Obesity is a chronic disease that often commences in childhood. Several publications have shown that a quarter to a third of Maltese children are overweight or obese. Malta will be the first country to measure height and weight (and hence Body Mass Index) for all school children in order to quantify the extent of the problem. Methods This study would include 46,000 children in 150 schools. This would be the first time that any country measured its entire childhood cohort, as opposed to sampling. Hence, it was decided to attempt to facilitate data collection and analysis with the use of bespoke spreadsheets. Results This paper will demonstrate how standard Microsoft Excel was used to accomplish this, greatly speeding up the data analysis process. Conclusion Software should be prepared in advance in anticipation of large amounts of data that need to be analysed and summarised. Particular care must be taken in order to prepare the requisite graphs and tables in advance so as to process the data once and present it in a suitable format for consumption and evaluation.peer-reviewe

Coherent forward stimulated Brillouin scattering of a spatially incoherent laser beam in a plasma and its effect on beam spray

A statistical model for forward stimulated Brillouin scattering (FSBS) is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. A threshold for the average power in a speckle is found, well below the self-focusing one, above which the laser beam spatial incoherence can not prevent the coherent growth of FSBS. Three-dimensional simulations confirm its existence and reveal the onset of beam spray above it. From these results, we propose a new figure of merit for the control of the propagation through a plasma of a spatially incoherent laser beam.Comment: submitted to PR

Effect of electron heating on self-induced transparency in relativistic intensity laser-plasma interaction

The effective increase of the critical density associated with the interaction of relativistically intense laser pulses with overcritical plasmas, known as self-induced transparency, is revisited for the case of circular polarization. A comparison of particle-in-cell simulations to the predictions of a relativistic cold-fluid model for the transparency threshold demonstrates that kinetic effects, such as electron heating, can lead to a substantial increase of the effective critical density compared to cold-fluid theory. These results are interpreted by a study of separatrices in the single-electron phase space corresponding to dynamics in the stationary fields predicted by the cold-fluid model. It is shown that perturbations due to electron heating exceeding a certain finite threshold can force electrons to escape into the vacuum, leading to laser pulse propagation. The modification of the transparency threshold is linked to the temporal pulse profile, through its effect on electron heating.Comment: 13 pages, 12 figures; fixed some typos and improved discussion of review materia

Fractal Markets Hypothesis and the Global Financial Crisis: Scaling, Investment Horizons and Liquidity

We investigate whether fractal markets hypothesis and its focus on liquidity and invest- ment horizons give reasonable predictions about dynamics of the financial markets during the turbulences such as the Global Financial Crisis of late 2000s. Compared to the mainstream efficient markets hypothesis, fractal markets hypothesis considers financial markets as com- plex systems consisting of many heterogenous agents, which are distinguishable mainly with respect to their investment horizon. In the paper, several novel measures of trading activity at different investment horizons are introduced through scaling of variance of the underlying processes. On the three most liquid US indices - DJI, NASDAQ and S&P500 - we show that predictions of fractal markets hypothesis actually fit the observed behavior quite well.Comment: 11 pages, 3 figure

Low Dose Ketamine for Opioid Refractory Cancer Pain

Background: Sub-anesthetic ketamine is used in the hospice and palliative setting to provide analgesia for opioid refractory cancer pain. While there are case reports supporting its use for this indication, results from the few studies done are mixed. Additionally, there are no widely agreed upon guidelines for dosing. The heterogeneous results may be attributed to small sample sizes and differing doses and routes of administration of ketamine. The objectives of this case presentation is to describe the successful use of sub-anesthetic ketamine in the management of high dose opioid refractory cancer pain and to propose a new area of study in the use of sub-anesthetic ketamine for management of an opioid refractory cancer pain. Case: A 32 year old male, receiving home hospice, with stage IV gastric adenocarcinoma, complicated by severe cancer-related abdominal pain presented to the ED in a pain crisis, agitated, confused and drowsy. His pain had been managed with a fentanyl PCA at home, with a 650 mcg/hr continuous infusion and a 200mcg demand dose with a 10 minute lockout. His fentanyl use escalated over the preceding days with 31,600 mcg of fentanyl (5266 oral morphine equivalents) in the 24 hours leading up to presentation. In the ED, his fentanyl PCA was continued and he was given hydromorphone 6mg IV and dexamethasone 10mg IV without effect. He was then given a 0.3 mg/kg ketamine bolus with improvement of his pain. He was subsequently admitted to the inpatient hospice unit for further pain management. He was initiated on a low dose ketamine infusion at 0.1mg/kg/hr and was rotated to a hydromorphone PCA at a continuous infusion of 13mg/hr (which is a 25% dose reduction from total fentanyl use) and a 10mg demand dose and 10 minute lockout. His ketamine infusion was titrated upwards to 0.2mg/kg/hr with improvement of his pain. He was maintained at this rate with adequate pain control while his hydromorphone PCA was able to be tapered down to a continuous infusion of 6mg/hr (decreased by 2mg/hr daily) and demand dose of 8mg with a 10 minute lockout. He was subsequently weaned off the ketamine infusion with sustained pain control and a 50% decrease in his opioid requirement. He experienced mild non-disturbing hallucinations and vivid dreams which were adequately controlled with haloperidol and lorazepam. The patient was able to be discharged home with adequate pain control on the hydromorphone PCA with home hospice. Conclusion: This case presentation adds to the other case reports supporting the utility of sub-anesthetic ketamine in the treatment of opioid refractory cancer pain. It also identifies the use of an initial sub-anesthetic ketamine bolus as a means to identify patients that are more likely to benefit from an infusion. Current studies in the medical literature are of small scale, vary in regards to dosing and routes of administration and provide heterogeneous results. Further studies are needed with larger sample sizes, consistent dosing and consistent routes of administration to draw more definitive conclusions regarding the utility of sub-anesthetic ketamine for opioid refractory cancer pain and to guide clinical practice. It is our suggestion that these studies also investigate the use of a sub-anesthetic ketamine bolus as a means to identify patients more likely to benefit from an infusion.https://scholarlycommons.henryford.com/merf2020caserpt/1093/thumbnail.jp

Endometrial adenocarcinoma in the Maltese population : an epidemiological study

The Maltese population has been shown to have a high incidence of endometrial adenocarcinoma when compared to other European countries. This high incidence has been correlated to the high prevalence of abnormal glucose metabolism and rather high dietary fat intake in the Maltese population. Hypertension and low parity were also found to be more frequent in the carcinoma group.peer-reviewe

High-quality ion beams by irradiating a nano-structured target with a petawatt laser pulse

We present a novel laser based ion acceleration scheme, where a petawatt circularly polarized laser pulse is shot on an ultra-thin (nano-scale) double-layer target. Our scheme allows the production of high-quality light ion beams with both energy and angular dispersion controllable by the target properties. We show that extraction of all electrons from the target by radiation pressure can lead to a very effective two step acceleration process for light ions if the target is designed correctly. Relativistic protons should be obtainable with pulse powers of a few petawatt. Careful analytical modeling yields estimates for characteristic beam parameters and requirements on the laser pulse quality, in excellent agreement with one and two-dimensional Particle-in Cell simulations.Comment: 18 pages, 7 figures, accepted in New. J. Phy

Strong inapproximability of the shortest reset word

The \v{C}ern\'y conjecture states that every $n$-state synchronizing automaton has a reset word of length at most $(n-1)^2$. We study the hardness of finding short reset words. It is known that the exact version of the problem, i.e., finding the shortest reset word, is NP-hard and coNP-hard, and complete for the DP class, and that approximating the length of the shortest reset word within a factor of $O(\log n)$ is NP-hard [Gerbush and Heeringa, CIAA'10], even for the binary alphabet [Berlinkov, DLT'13]. We significantly improve on these results by showing that, for every $\epsilon>0$, it is NP-hard to approximate the length of the shortest reset word within a factor of $n^{1-\epsilon}$. This is essentially tight since a simple $O(n)$-approximation algorithm exists.Comment: extended abstract to appear in MFCS 201