A simplified model of the source channel of the Leksell Gamma Knife(R)^(R): testing multisource configurations with PENELOPE

A simplification of the source channel geometry of the Leksell Gamma Knife$^{\circledR}$, recently proposed by the authors and checked for a single source configuration (Al-Dweri et al 2004), has been used to calculate the dose distributions along the $x$, $y$ and $z$ axes in a water phantom with a diameter of 160~mm, for different configurations of the Gamma Knife including 201, 150 and 102 unplugged sources. The code PENELOPE (v. 2001) has been used to perform the Monte Carlo simulations. In addition, the output factors for the 14, 8 and 4~mm helmets have been calculated. The results found for the dose profiles show a qualitatively good agreement with previous ones obtained with EGS4 and PENELOPE (v. 2000) codes and with the predictions of GammaPlan$^{\circledR}$. The output factors obtained with our model agree within the statistical uncertainties with those calculated with the same Monte Carlo codes and with those measured with different techniques. Owing to the accuracy of the results obtained and to the reduction in the computational time with respect to full geometry simulations (larger than a factor 15), this simplified model opens the possibility to use Monte Carlo tools for planning purposes in the Gamma Knife$^{\circledR}$.Comment: 13 pages, 8 figures, 5 table

A reconfigurable wideband and multiband antenna using dual-patch elements for compact wireless devices

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 IEEEA reconfigurable wideband and multiband C-Slot patch antenna with dual-patch elements is proposed and studied. It occupies a compact volume of 50 × 50 × 1.57 (3925 mm3), including the ground plane. The antenna can operate in two dual-band modes and a wideband mode from 5 to 7 GHz. Two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and the wideband modes. Two switches, implemented using PIN diodes, are placed on the connecting lines of a simple feed network to the patch elements. Dual-band modes are achieved by switching “ON” either one of the two patch elements, while the wideband mode with an impedance bandwidth of 33.52% is obtained by switching “ON” both patch elements. The frequencies in the dual-band modes can be independently controlled using positions and dimensions of the C-Slots without affecting the wideband mode. The advantage of the proposed antenna is that two dual-band operations and one wideband operation can be achieved using the same dimensions. This overcomes the need for increasing the surface area normally incurred when designing wideband patch antennas. Simulation results are validated experimentally through prototypes. The measured radiation patterns and peak gains show stable responses and are in good agreements. Coupling between the two patch elements plays a major role for achieving the wide bandwidth and the effects of mutual coupling between the patch elements are also studied

On a generalization of the risk model with Markovian claim arrivals

The class of risk models with Markovian arrival process (MAP) (see e.g., Neuts[15]) is generalized by allowing the waiting times between two successive events (which can be a change in the environmental state and/or a claim arrival) to have an arbitrary distribution. Using a probabilistic approach, we determine the solution for a class of Gerber-Shiu functions apart from some unknown constants when claim sizes have a mixed exponential distribution. Such constants are later determined using the more classic ruin-analytic approach. A numerical example is later considered to illustrate the tractability of the suggested methodology in the study of Gerber-Shiu functions. Copyright © 2011 Taylor &Francis Group, LLC.postprin

Recursive methods for a multi-dimensional risk process with common shocks

In this paper, a multi-dimensional risk model with common shocks is studied. Using a simple probabilistic approach via observing the risk processes at claim instants, recursive integral formulas are developed for the survival probabilities as well as for a class of Gerber-Shiu expected discounted penalty functions that include the surplus levels at ruin. Under the assumption of exponential or mixed Erlang claims, the recursive integrals can be simplified to give recursive sums which are computationally more tractable. Numerical examples including an optimal capital allocation problem are also given towards the end. © 2011 Elsevier B.V.postprin

Rotational and hyperfine analysis of the near infrared 3Φ4-X3Φ4 transitions of CoCl and Col

A rotational and hyperfine analysis of the 3φ 4- 3φ 4 transition of CoCl and CoI in the near infrared region was reported. Six and eight vibronic transition band soft CoCl and CoI, respectively, were recorded and analyzed. Accurate molecular parameters for both the upper and the ground 3φ 4 states were determined by least squares fitting of line positions of observed bands simultaneously for each molecule, which yielded accurate molecular parameters for both the upper and lower 3φ 4 states.published_or_final_versio

Achieving Synergistic Effects by Combining Different Phytochemicals for the Prevention and Treatment of Cancer

AL ZAHARNA, M & CHEUNG, HY 2014, 'Achieving Synergistic Effects by Combining Different Phytochemicals for the Prevention and Treatment of Cancer' Hong Kong Pharmaceutical Journal, vol 21, no. 1, pp. 20 - 24 … AL ZAHARNA, M., & CHEUNG, H. (2014). Achieving Synergistic Effects by Combining Different Phytochemicals for the Prevention and Treatment of Cancer. Hong Kong Pharmaceutical Journal, 21(1), 20 - 24 … AL ZAHARNA M, CHEUNG HY. Achieving Synergistic Effects by Combining Different Phytochemicals for the Prevention and Treatment of Cancer. Hong Kong Pharmaceutical Journal. 2014 Jan;21(1):20 - 24 … AL ZAHARNA, Mazen; CHEUNG, Hon-Yeung / Achieving Synergistic Effects by Combining Different Phytochemicals for the Prevention and Treatment of Cancer … In: Hong Kong Pharmaceutical Journal, Vol. 21, No. 1, 01.2014, p. 20 - 24

Delamination of polyimide in hydrofluoric acid

Wet etching is a critical fabrication step for the mass production of micro and nanoelectronic devices. However, when an extremely corrosive acid such as hydrofluoric (HF) acid are used during etching, an undesirable damage might occur if the device includes a material that is not compatible with the acid. Polyimide thin films can serve as sacrificial/structural layers to fabricate freestanding or flexible devices. The importance of polyimide in microelectronics is due to its relatively low stress and compatibility with standard micromachining processes. In this work, a fast delamination process of a 4-μm-thin film of polyimide from a silicon substrate has been demonstrated. The films’ detachment has been performed using a wet-based etchant of HF acid. Specifically, the effect of HF concentration on the delamination time required to detach the polyimide film from the substrate has been investigated. This study is intended to provide the information on the compatibility of using polyimide films with HF, which can help in the design and fabrication of polyimide-based devices

Posttraumatic Stress Among Syrian Refugees: Trauma Exposure Characteristics, Trauma Centrality, and Emotional Suppression

© Washington School of Psychiatry. Objectives: This study revisited the prevalence of posttraumatic stress disorder (PTSD) and examined a hypothesized model describing the interrelationship between trauma exposure characteristics, trauma centrality, emotional suppression, PTSD, and psychiatric comorbidity among Syrian refugees. Methods: A total of 564 Syrian refugees participated in the study and completed the Harvard Trauma Questionnaire, General Health Questionnaire (GHQ-28), Centrality of Event Scale, and Courtauld Emotional Control Scale. Results: Of the participants, 30% met the cutoff for PTSD. Trauma exposure characteristics (experiencing or witnessing horror and murder, kidnapping or disappearance of family members or friends) were associated with trauma centrality, which was associated with emotional suppression. Emotional suppression was associated with PTSD and psychiatric comorbid symptom severities. Suppression mediated the path between trauma centrality and distress outcomes. Conclusions: Almost one-third of refugees can develop PTSD and other psychiatric problems following exposure to traumatic events during war. A traumatized identity can develop, of which life-threatening experiences is a dominant feature, leading to suppression of depression with associated psychological distress