Computation of Electrostatic Field near Three-Dimensional Corners and Edges

Theoretically, the electric field becomes infinite at corners of two and three dimensions and edges of three dimensions. Conventional finite-element and boundary element methods do not yield satisfactory results at close proximity to these singular locations. In this paper, we describe the application of a fast and accurate BEM solver (which usesexact analytic expressions to compute the effect of source distributions on flatsurfaces) to compute the electric field near three-dimensional corners and edges. Results have been obtained for distances as close as 1$\mu m$ near the corner/edge and good agreement has been observed between the present results and existing analytical solutions.Comment: Presented in International Conference on Computational and Experimental Engineering and Sciences held at IIT Madras, Chennai, India, during 1-6 December, 200

Fast and air stable near-infrared organic detector based on squaraine dyes

In search for an organic material suitable for the detection of near-infrared electromagnetic radiation and at the same time capable of air stable operation of related devices, so to address the many applications envisaged with this technology (remote control, chemical/biological sensing, optical communication, spectroscopic and medical instruments), we explore the performance of a blend of hydrazone end-capped symmetric squaraines and phenyl C61 butyric acid methyl ester. We succeed in developing air stable solution-processed devices with external quantum efficiency in the NIR as high as 3.5% and response times of few hundreds of nanoseconds. Essential to these achievements has been a detailed characterization of the devices performed by correlating the optoelectronic performances to the morphology of the layers (extracted from AFM measurements) and to the charge carrier mobility (extracted from transistor structures), enabling their optimization at the chemical level, by tailoring the squaraine substitution pattern, and at the device level, by tuning the blend composition. We show that a good balance between holes and electrons mobility is essential for high EQE and fast response speed, and that a smooth morphology is mandatory to achieve long term air stability and operability with no need for encapsulation

Platinum diimine-dithiolate complexes as a new class of photoconducting compounds for pristine photodetectors: case study on [Pt(bipy)(Naph-edt)] (bipy = 2,2'-bipyridine; Naph-edt2- = 2-naphthylethylene-1,2-dithiolate)

The photoconducting properties of platinum diimine-dithiolate complex [Pt(bipy)(Naph-edt)] (1; bipy = 2,2 '-bipyridine; Naph-edt(2-) = 2-naphthylethylene-1,2-dithiolate) were investigated. DFT calculations on a model assembly with four complex units suggest that the high external quantum efficency measured on a prototype photodetector correlates with the intermolecular character of electronic excitations in the visible region

Prevalence of signs of nociception during physiotherapy in patient with disorders of consciousness.

Patients with disorders of consciousness (DOC) may suffer from neuro-orthopaedics disorders that can lead to potential pain during physiotherapy (PT). These patients are unable to communicate it is therefore a real challenge for clinicians to assess pain and adapt treatment. This randomized double-blind placebo-controlled study aimed to investigate the prevalence of signs of nociception during PT and their changes in relation to a pain-killer. During baseline (D0), pain responsiveness was assessed using the NCS-R (Nociception Coma Scale-Revised): at rest; during a tactile stimulation (TS); during a nociceptive stimulation (NS); and during PT. Then, patient with signs of potential pain during PT was assessed during a placebo and a pain-killer condition (D1 and D2). Our results show that most DOC patients present signs of potential pain during PT (14/19; 73.4%), and a few of them already received analgesic treatment before the study (5/14, 35.7%). During baseline, we found significant differences between the NCS-R score during PT than the three others stimulation, suggesting that passive mobilizations are potentially painful for DOC patient. These difference remains during placebo and treatment condition expect with the NS. We do not found an effect of pain-killer on the NCS-R score during PT and NS. This could be explained by the fact that the NCS-R failed to detect the effect of pain-killer or that this effect was not strong enough. This study point-out that PT may be painful for DOC patients and appropriate assessment and treatment before and during mobilizations should become a priority in clinical setting

Squaraine-based organic photodetector coupled to a scintillating crystal for X-ray sensing applications

To the aim of developing an X-ray imager based on a scintillator coupled to an organic photodetector, we fabricated and tested a detector pixel whose active material is a blend of squaraine dyes and Phenyl-C61-Butyric-Acid-Methyl-Ester (PCBM), processed to obtain a detector thickness of 2μm and a leakage current, at the operating voltage, below 10nA/cm2. The detector was coupled to a CsI(Tl) scintillator crystal obtaining, upon collimated 30keV x-ray beam, clear current signals of few hundreds of pA for a dose less than 5μGray/s, both in QCW and under 500μs long pulses. In addition, the development of the pixel on a flexible and transparent substrate leads to a better scintillator light collection

Evaluation of the effect of analgesic treatment on signs of nociception-related behaviors during physiotherapy in patients with disorders of consciousness: a pilot crossover randomized controlled trial

Neuro-orthopedic disorders are common in patients with disorders of consciousness (DOC) and can lead to potential pain. However, the patients' inability to communicate makes pain detection and management very challenging for clinicians. In this crossover randomized double-blind placebo-controlled study, we investigated the effects of an analgesic treatment on the presence of nociception-related behaviors. At baseline, the Nociception Coma Scale-Revised (NCS-R) was performed in 3 conditions: a non-noxious stimulation, a noxious stimulation, and during a physiotherapy session. Patients with a NCS-R total score during physiotherapy equal or above the score observed after the noxious stimulation could participate to the clinical trial, as well as patients with a score above 5. They received an analgesic treatment and a placebo on 2 consecutive days in a randomized order followed by an assessment with the NCS-R. Of the 18 patients, 15 displayed signs of potential pain during physiotherapy. Patients showed higher NCS-R scores during physiotherapy compared with the other conditions, suggesting that mobilizations were potentially painful. Of these 15 patients, 10 met the criteria to participate in the placebo-controlled trial. We did not find any effect of analgesic treatment on the NCS-R scores. This study highlights that physiotherapy may be potentially painful for patients with DOC, while analgesic treatments did not reduced NCS-R scores. Therefore, careful monitoring with appropriate assessment and treatment before and during mobilization should become a priority in clinical settings. Future studies should focus on the development of assessment tools sensitive to analgesic dosage to manage pain in DOC

Pain management in Disorders of Consciousness

Background: Patients with disorders of consciousness (DOC) are unable to communicate about their feelings and therefore they cannot express potential painful sensation. The Nociceptive Coma Scale-Revised (NCS-R) is a valuable tool to assess nociception in those patients (Chatelle et al. 2018; Schnakers and Zasler 2007; Chatelle et al. 2012). In the present study, we aimed at investigating the use of the NCS-R in chronic patients with DOC to monitor behavioural responses to potential painful stimulation, i.e. during physical therapy (PT), as it may potentially induce a painful sensation given the common presence of neuro-orthopaedic disorders in these severely brain-injured patients and especially in case of spasticity (Thibaut et al. 2015). In this randomized double-blind placebo-controlled protocol, we investigated the prevalence of signs of nociception during PT and their changes in relation to an analgesic treatment. Methods: We enrolled chronic (>3 months post-injury) patients in unresponsive wakefulness syndrome (UWS - Laureys et al. 2010) or minimally conscious state (MCS - Giacino et al. 2002) over 16 years old. We excluded patients with documented neurological disorders prior to the acquired brain damage. The level of consciousness was assessed with the Coma Recovery Scale-Revised (CRS-R - Giacino et al. 2004). The behavioural responses related to nociception were assessed using the NCS-R (Chatelle et al. 2012), in four different conditions: a) at rest; b) during a tactile stimulation (i.e., 5 claps on the right and left hand); c) during a nociceptive stimulation (i.e., pressure on the nailbed of the right and left middle finger); and d) during PT. If the score observed during the PT was higher or equal to the one observed during the nociceptive stimulation or if the score was equal or higher than 4 (threshold previously defined - Chatelle et al. 2012), he/she was enrolled in the second phase of the study (i.e., randomized placebo-controlled protocol). In this phase, the patient was assessed twice within 24 hours during a PT session with the same therapist, once when receiving an active pain-killer (tailored on the patient’s medication - Ventafridda et al. 1985) and once after a placebo, administered in a randomized double-blind placebo-controlled manner. The CRS-R was also administered after each PT session to control for changes in the level of consciousness due to pain medication. We used a Friedman Anova to investigate the difference in NCS-R scores between all the conditions (i.e., rest, tactile, nociceptive and during PT). Wilcoxon matched pairs signed rank tests were then used as post hoc analyses. Given the number of patients included in the second phase of the study, we also used descriptive analyses to characterize the effect of analgesics on NCS-R scores. Results: In this preliminary dataset, 6 patients were enrolled (1 UWS, 5 MCS, see table 1). Demographics and NCS-R scores during the first evaluation are reported in table 1 and figure 1. NCS-R total scores differed between all the conditions (χ2 = 12.9; p = 0.005). NCS-R total scores were higher during PT than at rest (p = 0.034) or after the tactile stimulation (p = 0.036). Five out of 6 patients met the criteria for being enrolled in the second phase of the study (i.e., presented signs of nociception during PT more or equal than during the nociceptive stimulation or an NCS-R score during PT higher or equal to 4, see table 2). Two patients were excluded from the analysis for scheduling reasons preventing a standardized application of the protocol. Regarding the three patients included in the phase 2, only one had an improvement in the NCS-R after treatment compared to placebo (decrease of the NCS-R score from 3 at the first evaluation to 0 after treatment and to 2 after placebo), while the NCS-R score did not change for the other two patients after treatment and placebo. The CRS-R based diagnosis remained unchanged for all the patients. Conclusions: In this preliminary dataset, our results show that most patients with DOC present signs of potential pain as measured by the NCS-R during PT (5/6; 83.3%). Indeed, we found a significant difference between the NCS-R score during PT than at rest or after a tactile stimulation, suggesting that passive mobilizations are potentially painful for patients with DOC. Regarding the second phase of the study, even if we found a decrease in the pain score after the treatment with paracetamol in one patient, this was not the case for the other two patients included as their NCS-R scores remained unchanged. This could be explained by the fact that the analgesic treatment was not enough to decrease pain. It could also be due to a failure of the NCS-R to detect the positive effect of an analgesic treatment. Additionally, it is important to highlight that 4 of the 5 patients showing signs of pain during PT were not receiving chronic analgesic treatment at the time of enrollment. Although chronic analgesic therapy is not necessary for all patients, it is crucial to pay attention to the signs of nociception during mobilizations and cares and to provide an adequate treatment. If these results are preliminary, we point-out that PT may be painful for DOC patients and appropriate assessment and treatment before and during mobilizations should become a priority in the clinical setting. In the future, we should also correlate the NCS-R scores with the fluctuations of consciousness (i.e. CRS-R scores) and the variations of spasticity (i.e. Modified Ashworth Scale scores - Mehrholz et al. 2005) during mobilization when analgesics are administered