572 research outputs found
High Extinction Ratio Polarization Selective TE/TM Bragg Gratings Filters on Silicon-on-insulator
No abstract available
High-extinction-ratio TE/TM selective Bragg grating filters on silicon-on-insulator
We report on the design and fabrication of TE and TM polarization selective Bragg grating filters in the form of sinusoidal perturbations on the waveguide sidewall and etched holes on the top of the waveguide, respectively. Combining the two geometries on a silicon-on-insulator waveguide resulted in Bragg grating filters with high extinction ratios of approximately 60 dB
High-extinction-ratio TE/TM selective Bragg grating filters on silicon-on-insulator
We report on the design and fabrication of TE and TM polarization selective Bragg grating filters in the form of sinusoidal perturbations on the waveguide sidewall and etched holes on the top of the waveguide, respectively. Combining the two geometries on a silicon-on-insulator waveguide resulted in Bragg grating filters with high extinction ratios of approximately 60 dB
Cortical pain responses in human infants
Despite the recent increase in our understanding of the development of pain processing, it is still not known whether premature infants are capable of processing pain at a cortical level. In this study, changes in cerebral oxygenation over the somatosensory cortex were measured in response to noxious stimulation using real-time near-infrared spectroscopy in 18 infants aged between 25 and 45 weeks postmenstrual age. The noxious stimuli were heel lances performed for routine blood sampling; no blood tests were performed solely for the purpose of the study. Noxious stimulation produced a clear cortical response, measured as an increase in total hemoglobin concentration [HbT] in the contralateral somatosensory cortex, from 25 weeks (mean Delta[HbT] = 7.74 mu mol/L; SE, 1.10). Cortical responses were significantly greater in awake compared with sleeping infants, with a mean difference of 6.63 mu mol/L [95% confidence interval (CI) limits: 2.35, 10.91 mu mol/L; mean age, 35.2 weeks]. In awake infants, the response in the contralateral somatosensory cortex increased with age ( regression coefficient, 0.698 mu mol/L/week; 95% CI limits: 0.132, 1.265 mu mol/L/week) and the latency decreased with age (regression coefficient, -0.9861 mu mol/L/week; 95% CI limits: -1.5361, -0.4361 mu mol/L/week; age range, 25-38 weeks). The response was modality specific because no response was detected after non-noxious stimulation of the heel, even when accompanied by reflex withdrawal of the foot. We conclude that noxious information is transmitted to the preterm infant cortex from 25 weeks, highlighting the potential for both higher-level pain processing and pain-induced plasticity in the human brain from a very early age
Knot Fertility and Lineage
In this paper, we introduce a new type of relation between knots called the
descendant relation. One knot is a descendant of another knot if
can be obtained from a minimal crossing diagram of by some number of
crossing changes. We explore properties of the descendant relation and study
how certain knots are related, paying particular attention to those knots,
called fertile knots, that have a large number of descendants. Furthermore, we
provide computational data related to various notions of knot fertility and
propose several open questions for future exploration.Comment: 20 pages, 11 figures, 14 table
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Ectopic expression of the HLXB9 gene is associated with an altered nuclear position in t(7;12) leukaemias
This article is available open access through the publisher’s website at the link below. Copyright @ 2009 Macmillan Publishers Ltd.No abstract available (Letter to the editor).The Leukaemia Research Fun
Integrated microrings for on-chip filtering and efficient FWM generation
A silicon micro-ring device with tunable four-wave mixing efficiency is presented. The micro-ring is monolithically integrated with a dual polarisation filter based on a cascaded three ring resonator geometry. Four-wave mixing is demonstrated with signal and idler transmitted through the filter with only 1.8 dB of insertion loss. The pump light is rejected with over 62 dB extinction for both TE and TM guided modes
Silicon photonic filters with high rejection of both TE and TM modes for on-chip four wave mixing applications
Wavelength selective filters represent one of the key elements for photonic integrated circuits (PIC) and many of their applications in linear and non-linear optics. In devices optimised for single polarisation operation, cross-polarisation scattering can significantly limit the achievable filter rejection. An on-chip filter consisting of elements to filter both TE and TM polarisations is demonstrated, based on a cascaded ring resonator geometry, which exhibits a high total optical rejection of over 60 dB. Monolithic integration of a cascaded ring filter with a four-wave mixing micro-ring device is also experimentally demonstrated with a FWM efficiency of -22dB and pump filter extinction of 62dB
Rigid Origami Vertices: Conditions and Forcing Sets
We develop an intrinsic necessary and sufficient condition for single-vertex
origami crease patterns to be able to fold rigidly. We classify such patterns
in the case where the creases are pre-assigned to be mountains and valleys as
well as in the unassigned case. We also illustrate the utility of this result
by applying it to the new concept of minimal forcing sets for rigid origami
models, which are the smallest collection of creases that, when folded, will
force all the other creases to fold in a prescribed way
Comparing Signal Setting Design Methods through emissions and fuel consumption performance indicators
In order to address the Signal Setting Design at urban level two main approaches may be pursued: the coordination and the synchronisation approaches depending on the steps considered for the optimisation of decision variables (two steps vs. one step). Furthermore, in terms of objective functions mono-criterion or multi-criteria may be adopted. In this paper the coordination approach is implemented considering the multi-criteria optimisation at single junctions and mono-criterion optimisation at network level whereas the synchronisation is implemented considering the mono-criterion optimisation. The main purpose of the paper is the evaluation of the performances of two strategies not only considering indicators such as the total delay, the queue length etc. but also considering other indicators such as the emissions and the fuel consumption. The methodological framework is composed by three stages: (i) the decision variables (green timings and offsets) computation through optimisation methods; (ii) the implementation of optimal signal settings in a microscopic traffic flow simulator (“Simulation of Urban MObility”-SUMO); (iii) the estimation of emissions and fuel consumption indicators
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