Focused Ion Beam Milling Strategies of Photonic Crystal Structures in Silicon

We report on optimisation of the side wall angle of focused ion beam (FIB) fabricated submicron diameter holes in silicon. Two optimisation steps were performed. First, we compare two different FIB scanning procedures and show the advantages of using a spiral scanning method for the definition of holes in photonic crystal slab structures. Secondly, we investigate the effect on the geometry, of parameters for reducing the tapering effect. Furthermore, we report on the initial results regarding effects of $Ga^{+}$ ion implantation during FIB milling on optical losses, both before and after an annealing step, showing over a decade reduction of optical loss

Realization of 2-dimensional air-bridge silicon photonic crystals by focused ion beam milling and nanopolishing

We report the design and fabrication of small photonic crystal structures which are combined with conventional dielectric ridge waveguides. We describe in details the fabrication of both rough and smooth membranes, which are used as host for photonic crystals. Two Focused Ion Beam milling experiments are highlighted: the first one shows how photonic crystals can be fast and accurate milled into a Si membrane, whereas the second experiment demonstrates how focused ion beam milling can turn a rough surface into a well-patterned nano-smooth surface. The previously ultra rough surface showed no detectable roughness after milling due to the nanopolishing effect of the focused ion beam milling

Fast prototyping of planar photonic crystal components using a combination of optical lithography and focused ion beam etching

A combination of conventional optical lithography and focused ion beam etching provides a novel method for fast and precise (10 nm accuracy) prototyping of planar photonic crystal structures having submicron features, in silicon on insulator wafers

Free-carrier-induced soliton fission unveiled by in situ measurements in nanophotonic waveguides

Solitons are localized waves formed by a balance of focusing and defocusing effects. These nonlinear waves exist in diverse forms of matter yet exhibit similar properties including stability, periodic recurrence and particle-like trajectories. One important property is soliton fission, a process by which an energetic higher-order soliton breaks apart due to dispersive or nonlinear perturbations. Here we demonstrate through both experiment and theory that nonlinear photocarrier generation can induce soliton fission. Using near-field measurements, we directly observe the nonlinear spatial and temporal evolution of optical pulses in situ in a nanophotonic semiconductor waveguide. We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude. We confirm these observations with a numerical nonlinear Schrödinger equation model. These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides

A preliminary investigation of schematic beliefs and unusual experiences in children

Background In cognitive models of adult psychosis, schematic beliefs about the self and others are important vulnerability and maintaining factors, and are therefore targets for psychological interventions. Schematic beliefs have not previously been investigated in children with distressing unusual, or psychotic-like, experiences (UEDs). The aim of this study was firstly to investigate whether a measure of schematic beliefs, originally designed for adults with psychosis, was suitable for children; and secondly, to examine the association of childhood schematic beliefs with internalising and externalising problems and with UEDs. Method Sixty-seven children aged 8–14 years, with emotional and behavioural difficulties, completed measures of UEDs, internalising (depression and anxiety), and externalising (conduct and hyperactivity-inattention) problems, together with the Brief Core Schema Scales (BCSS). Results The BCSS was readily completed by participants, and scale psychometric properties were good. Children tended to view themselves and others positively. Internalising and externalising problems and UEDs were all associated with negative schematic beliefs; effect sizes were small to medium. Conclusions Schematic beliefs in young people can be measured using the BCSS, and negative schematic beliefs are associated with childhood psychopathology and with UEDs. Schematic beliefs may therefore form a useful target in psychological interventions for young people with UEDs

Effects of multidimensional treatment foster care on psychotic symptoms in girls

Objective Neurodevelopmental theories of psychosis highlight the potential benefits of early intervention, prevention, and/or preemption. How early intervention should take place has not been established, nor whether interventions based on social learning principles can have preemptive effects. The objective was to test whether a comprehensive psychosocial intervention can significantly alter psychotic symptom trajectories during adolescence—a period of heightened risk for a wide range of psychopathology. Method This study was a randomized controlled trial (RCT) of Multidimensional Treatment Foster Care (MTFC) for delinquent adolescent girls. Assessment of psychotic symptoms took place at baseline and then 6, 12, 18, and 24 months post-baseline using a standardized self-report instrument (Brief Symptom Inventory). A second source of information about psychotic symptoms was obtained at baseline or 12 months, and again at 24 months using a structured diagnostic interview (the Diagnostic Interview Schedule for Children [DISC]). Results Significant benefits for MTFC over treatment as usual for psychosis symptoms were observed over a 24-month period. Findings were replicated across both measures. Effects were independent of substance use and initial symptom severity and persisted beyond the initial intervention period. Conclusion Ameliorating nonclinical psychotic symptoms trajectories beginning in mid-adolescence via a multifaceted psychosocial intervention is possible. Developmental research on nonclinical psychotic symptoms and their prognostic value should be complemented by more psychosocial intervention research aimed at modifying these symptom trajectories early in their natural history. Clinical trial registration information—Juvenile Justice Girls Randomized Control Trial: Young Adult Follow-up; http://clinicaltrials.gov; NCT01341626

Author index for volume 103

Coping with unusual experiences for 12–18 year olds (CUES+): SPIRIT Checklist. (DOC 122 kb

Preoperative biliary drainage for periampullary tumors causing obstructive jaundice; DRainage vs. (direct) OPeration (DROP-trial)

BACKGROUND: Surgery in patients with obstructive jaundice caused by a periampullary (pancreas, papilla, distal bile duct) tumor is associated with a higher risk of postoperative complications than in non-jaundiced patients. Preoperative biliary drainage was introduced in an attempt to improve the general condition and thus reduce postoperative morbidity and mortality. Early studies showed a reduction in morbidity. However, more recently the focus has shifted towards the negative effects of drainage, such as an increase of infectious complications. Whether biliary drainage should always be performed in jaundiced patients remains controversial. The randomized controlled multicenter DROP-trial (DRainage vs. Operation) was conceived to compare the outcome of a 'preoperative biliary drainage strategy' (standard strategy) with that of an 'early-surgery' strategy, with respect to the incidence of severe complications (primary-outcome measure), hospital stay, number of invasive diagnostic tests, costs, and quality of life. METHODS/DESIGN: Patients with obstructive jaundice due to a periampullary tumor, eligible for exploration after staging with CT scan, and scheduled to undergo a "curative" resection, will be randomized to either "early surgical treatment" (within one week) or "preoperative biliary drainage" (for 4 weeks) and subsequent surgical treatment (standard treatment). Primary outcome measure is the percentage of severe complications up to 90 days after surgery. The sample size calculation is based on the equivalence design for the primary outcome measure. If equivalence is found, the comparison of the secondary outcomes will be essential in selecting the preferred strategy. Based on a 40% complication rate for early surgical treatment and 48% for preoperative drainage, equivalence is taken to be demonstrated if the percentage of severe complications with early surgical treatment is not more than 10% higher compared to standard treatment: preoperative biliary drainage. Accounting for a 10% dropout, 105 patients are needed in each arm resulting in a study population of 210 (alpha = 0.95, beta = 0.8). DISCUSSION: The DROP-trial is a randomized controlled multicenter trial that will provide evidence whether or not preoperative biliary drainage is to be performed in patients with obstructive jaundice due to a periampullary tumor

CMS physics technical design report : Addendum on high density QCD with heavy ions

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