A VIEWPOINT OF REGIONAL RESEARCH

Research and Development/Tech Change/Emerging Technologies,

Efficient third harmonic generation in photonic nanowires

In a photonic nanowire the strong optical confinement allows for the phase matching of nonlinear interactions that would not normally be phase matched, while the large longitudinal component of the electric field serves to further enhance the effective nonlinearity. Thus such waveguides are good choices for studying nonlinear effects such as third harmonic generation. In this paper we analyse third harmonic generation analytically and present the criteria for optimal harmonic generation. In addition we analyse the inverse process of 1/3 harmonic generation and show that efficient parametric amplifiers can be made which would be a high brightness source of entangled photons for producing GHZ states

Efficient low-threshold lasers based on an erbium-doped holey fiber

We report experimental results on the continuous-wave lasers based on a small core erbium-doped holey fiber. In a simple Fabry-Perot-type cavity with high output coupling, we demonstrate low-threshold (0.55 mW) high slope-efficiency (57.3%) operation confirming both the quality and exceptionally high gain efficiency of the fiber. In an all-fiber ring cavity where the cavity loss is reduced, we show that it is possible to achieve a low-threshold laser with extremely wide tunability (>100 nm around 1550 nm). Our results illustrate some of the unique opportunities provided by active small core holey fibers

A holey fiber based Brillouin laser

We demonstrate for the first time a Brillouin laser based on a Holey Fiber (HF). Using a simple Fabry-Perot resonator scheme containing a 75m long highly nonlinear HF with an effective area of 2.85µm2 we obtain a threshold of 125mW and a slope efficiency of ~70%

The quick and the dead: when reaction beats intention

Everyday behaviour involves a trade-off between planned actions and reaction to environmental events.Evidence from neurophysiology, neurology and functional brain imaging suggests different neural bases for the control of different movement types. Here we develop a behavioural paradigm to test movement dynamics for intentional versus reaction movements and provide evidence for a ‘reactive advantage’ in movement execution, whereby the same action is executed faster in reaction to an opponent. We placed pairs of participants in competition with each other to make a series of button presses. Within subject analysis of movement times revealed a 10 per cent benefit for reactive actions. This was maintained when opponents performed dissimilar actions, and when participants competed against a computer, suggesting that the effect is not related to facilitation produced by action observation. Rather, faster ballistic movements may be a general property of reactive motor control, potentially providing a useful means of promoting survival

Potential of eye movement desensitization and reprocessing therapy in the treatment of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) continues to attract both empirical and clinical interest due to its complex symptom profile and the underlying processes involved. Recently, research attention has been focused on the types of memory processes involved in PTSD and hypothesized neurobiological processes. Complicating this exploration, and the treatment of PTSD, are underlying comorbid disorders, such as depression, anxiety, and substance use disorders. Treatment of PTSD has undergone further reviews with the introduction of eye movement desensitization and reprocessing (EMDR). EMDR has been empirically demonstrated to be as efficacious as other specific PTSD treatments, such as trauma-focused cognitive behavioral therapy. There is emerging evidence that there are different processes underlying these two types of trauma treatment and some evidence that EMDR might have an efficiency advantage. Current research and understanding regarding the processes of EMDR and the future direction of EMDR is presented.

Normal, Abby Normal, Prefix Normal

A prefix normal word is a binary word with the property that no substring has more 1s than the prefix of the same length. This class of words is important in the context of binary jumbled pattern matching. In this paper we present results about the number $pnw(n)$ of prefix normal words of length $n$, showing that $pnw(n) =\Omega\left(2^{n - c\sqrt{n\ln n}}\right)$ for some $c$ and $pnw(n) = O \left(\frac{2^n (\ln n)^2}{n}\right)$. We introduce efficient algorithms for testing the prefix normal property and a "mechanical algorithm" for computing prefix normal forms. We also include games which can be played with prefix normal words. In these games Alice wishes to stay normal but Bob wants to drive her "abnormal" -- we discuss which parameter settings allow Alice to succeed.Comment: Accepted at FUN '1

Resource variation in colorectal surgery; a national centre-level analysis.

BACKGROUND: Delivery of quality colorectal surgery requires adequate resources. We set out to assess the relationship between resources and outcomes in English colorectal units. METHODS: Data was extracted from the ACPGBI resource questionnaire to profile resources. This was correlated with Hospital Episode Statistics (HES) outcome data including 90-day mortality and readmissions. Patient satisfaction measures were extracted from the Cancer Experience Patient Survey (CEPS) and compared at unit level. Centres were divided by workload into low, middle, and top tertile. RESULTS: Completed questionnaires were received from 75 centres in England. Service resources were similar between low and top tertiles in access to CEPOD theatre, level 2 or 3 beds per 250,000 population or likelihood of having a dedicated colorectal ward. There was no difference in staffing levels per 250,000 unit of population. Each 10% increase in the proportion of cases attempted laparoscopically, was associated with reduced 90-day unplanned readmission (RR 0.94, 95% CI 0.91 to 0.97, p<0.001). The presence of a dedicated colorectal ward (RR 0.85, 95% CI 0.73 to 0.99, p =0.040) was also associated with a significant reduction in unplanned readmissions. There was no association between staffing or service factors and patient satisfaction. DISCUSSION AND CONCLUSIONS: Resource levels do not vary based on unit of population. There is benefit associated with increased use of laparoscopy and a dedicated surgical ward. Alternative measures to assess the relationship between resources and outcome, such as failure to rescue, should be explored in UK practice. This article is protected by copyright. All rights reserved

Risk factors for ischaemic colitis after surgery for abdominal aortic aneurysm: a systematic review and observational meta-analysis

BACKGROUND: Ischaemic colitis is an infrequent but serious complication following repair of abdominal aortic aneurysm (AAA), with high mortality rates. This systematic review set out to identify risk factors for the development of ischaemic colitis after AAA surgery. METHODS: A systematic search of the MEDLINE, EMBASE and CINAHL databases was performed. This search was limited to studies published in the English language after 1990. Abstracts were screened by two authors. Eligible studies were obtained as full text for further examination. Data was extracted by two authors, and any disputes were resolved via consensus. Extracted data was pooled using Mantel-Haenszel random effects models. Bias was assessed using two Cochrane-approved tools. Effect sizes are expressed as relative risk ratios alongside the 95 % confidence interval. Statistical significance was defined at the level of p < 0.05. RESULTS: From 388 studies identified in the initial search, 33 articles were included in the final synthesis and analysis. Risk factors were grouped into patient (female gender, disease severity) and operative factors (peri-procedural hypotension, operative modality). The risk of ischaemic colitis was significantly higher when undergoing emergency repair versus elective (risk ratio (RR) 7.36, 3.08 to 17.58, p < 0.001). Endovascular repair reduced the likelihood of ischaemic colitis (RR 0.22, 0.12 to 0.39, p < 0.001). DISCUSSION: The quality of published evidence on this subject is poor with many retrospective datasets and inconsistent reporting across studies. Despite this, emergency presentation and open repair should prompt close monitoring for the development of IC

Radiative Decays of Decuplet to Octet Baryons in Light Cone QCD

The radiative decays of decuplet to octet baryons are analyzed within the light cone QCD sum rules framework.The electromagnetic transition form factors for these decays are calculated up to twist four accuracy for photon wave functions as well as including first order strange quark mass corrections. A comparison of our results with predictions of lattice theory and existing experimental data is presented.Comment: 43 pages, 30 figures, uses graphicx and amssymb, included a more general analysis, Conclusions change