Low loss silicon waveguides for the mid-infrared Mashanovich, Goran Z; Milošević, Milan M; Nedeljkovic, Milos ...
Optics express,
2011-Apr-11, 2011-04-11, 20110411, Letnik:
19, Številka:
8
Journal Article
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Silicon-on-insulator (SOI) has been used as a platform for near-infrared photonic devices for more than twenty years. Longer wavelengths, however, may be problematic for SOI due to higher absorption ...loss in silicon dioxide. In this paper we report propagation loss measurements for the longest wavelength used so far on SOI platform. We show that propagation losses of 0.6-0.7 dB/cm can be achieved at a wavelength of 3.39 µm. We also report propagation loss measurements for silicon on porous silicon (SiPSi) waveguides at the same wavelength.
We introduce a hyperuniform-disordered platform for the realization of near-infrared photonic devices on a silicon-on-insulator platform, demonstrating the functionality of these structures in a ...flexible silicon photonics integrated circuit platform unconstrained by crystalline symmetries. The designs proposed advantageously leverage the large, complete, and isotropic photonic band gaps provided by hyperuniform disordered structures. An integrated design for a compact, sub-volt, sub-fJ/bit, hyperuniform-clad, electrically controlled resonant optical modulator suitable for fabrication in the silicon photonics ecosystem is presented along with simulation results. We also report results for passive device elements, including waveguides and resonators, which are seamlessly integrated with conventional silicon-on-insulator strip waveguides and vertical couplers. We show that the hyperuniform-disordered platform enables improved compactness, enhanced energy efficiency, and better temperature stability compared to the silicon photonics devices based on rib and strip waveguides.
One of the side-effects of the COVID-19 pandemic is a global change in work ergonomic patterns as millions of people replaced their usual work environment with home to limit the spread of the severe ...acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection. The aim of our cross-sectional pilot study was to identify musculoskeletal pain that may have resulted from this change and included 232 telecommunications company workers of both genders 121 (52.2 %) men aged 23–62 (median 41; interquartile range 33–46 yrs.) and 111 (47.8 %) women aged 23–53 (median 40; interquartile range 33–44) who had been working from home for eight months (from 16 March to 4 December 2020) before they joined the study. The participants were asked to fill in our web-based questionnaire by self-assessing their experience of hand, lower back, and upper back/neck pain while working at home and by describing their work setting and physical activity. Compared to previous work at the office, 90 (39.1 %) participants reported stronger pain in the lower back, 105 (45.7 %) in the upper back/neck, and 63 (27.2 %) in their hands. Only one third did not report any musculoskeletal problems related to work from home. Significantly fewer men than women reported hand, lower back, and upper back/ neck pain (p=0.033, p=0.001 and p=0.013, respectively). Sixty-nine workers (29.9 %) reported to work in a separate room, 75 (32.4 %) worked in a separate section of a room with other household members, whereas 87 (37.7 %) had no separate work space, 30 of whom most often worked in the dining room. Ninety-five participants (40.9 %) had no office desk to work at, and only 75 (32.3 %) used an ergonomic chair. Of those who shared their household with others (N=164), 116 (70.7 %) complained about constant or occasional disturbances. Over a half of all participants (52 %) said that they worked longer hours from home than at work, predominantly women (p=0.05). Only 69 participants (29.9 %) were taking frequent breaks, predominantly older ones (p=0.006). Our findings clearly point to a need to inform home workers how to make more ergonomic use of non-ergonomic equipment, use breaks, and exercise and to inform employers how to better organise working hours to meet the needs of work from home.
Purpose
Acute hydrocephalus is a common complication after aneurysmal subarachnoid hemorrhage (aSAH). It can be self-limiting or require cerebrospinal fluid diversion. We aimed to determine the ...transient acute hydrocephalus (TAH) rate in patients with aSAH treated endovascularly and evaluate its predictive factors.
Methods
A retrospective review of 357 patients with aSAH who underwent endovascular treatment from March 2013 to December 2019 was performed. Clinical and radiographic data were analyzed and risk factors with potential significance for acute hydrocephalus were identified. We constructed a new risk score, the Drainage Or Transiency of Acute Hydrocephalus after Aneurysmal SAH (DOTAHAS) score, that may differentiate patients who would experience TAH from those needing surgical interventions.
Results
Acute hydrocephalus occurred in 129 patients (36%), out of whom in 66 patients (51%) it was self-limiting while 63 patients (49%) required external ventricular drainage placement. As independent risk factors for acute hydrocephalus, we identified older age, poor initial clinical condition, aSAH from posterior circulation, and the extent of cisternal and intraventricular hemorrhage. The following three factors were shown to predict acute hydrocephalus transiency and therefore included in the DOTAHAS score, ranging from 0 to 7 points: Hunt and Hess grade ≥ 3 (1 point), modified Fisher grade 4 (2 points), and Ventricular Hijdra Sum Score (vHSS) ≥ 6 (4 points). Patients scoring ≥ 3 points had significantly higher risk for EVD (
P
< 0.0001) than other patients.
Conclusion
The newly developed DOTAHAS score can be useful in identifying patients with transient acute hydrocephalus. Further score evaluation is needed.
Safety management is a new scientific discipline that was created by merging two sciences, safety science and management science. Modern security threats, which have been increasing recently, have ...led to an increased interest in security issues, as well as in organizations that deal with these issues. In accordance with the changes that have occurred in the field of security, different theories and schools of security have also developed and changed. The aim of this paper is, therefore, to present different approaches in the study of security management as a scientific discipline, and to point out the similarities and differences between the presented theories and schools. The paper presents the traditional - voluntarist approach and alternative approaches to security. Contemporary problems of safety management with the challenges ahead are also given.
The
Challenge-20
is an assessment of advanced motor skills of children with cerebral palsy. The purpose of this study was to develop age-related norms and percentile curves for the
Challenge-20
with ...typically developing children (
n
= 150, 7 through 11 years), and compare
Challenge-20
scores of independently ambulatory children with CP, Gross Motor Function Classification System level I (
n
= 135) and II (
n
= 56) to these age norms. Younger TD children (7 years) scored lowest, and older children (11 years) scored highest on the
Challenge-20
, showing similar developmental trajectories.
Challenge-20
scores of 15% of children in GMFCS level I were situated above the lower 2.5th percentile curve of the typically developing children’s
Challenge-20
growth curve, that is, overlapping into the typically developing child zone. The
Challenge-20
is sensitive to the progression of advanced gross motor skills in typically developing children. Children with cerebral palsy, GMFCS I follow similar, albeit lower,
Challenge
score trajectory to that of typically developing children, and in some cases come close to lower level abilities of typically developing children. The reference values with typically developing children extend the
Challenge-20
‘s utility when assessing advanced gross motor skill of independently ambulatory children with cerebral palsy for physiotherapy intervention and physical activity planning and open the door to re-thinking more about advanced gross motor interventions for children with cerebral palsy in GMFCS levels I and II given their potential to progress along the developmental trajectory.
Although the role of microbiota has been investigated in relation to different oral diseases, it is unknown if its composition has any effect on the course of recovery after third molar alveotomy. ...Our aim was to determine the influence of patient clinical characteristics as well as pericoronary microbiota composition on the course of recovery after a semi-impacted third molar alveotomy. Thirty-six patients were included and samples obtained with paper points, swabs, and tissue samples were analyzed using DNA hybridization and culture methods. Among the 295 organisms detected, the most frequent were
spp. (22.4%; 66/295) followed by
spp. (11.9%; 35/295), and
(9.1%; 27/295). A comparison of microbiota composition in patients with better and worse recovery did not show significant differences. Worse recovery outcomes were more frequent in patients with a grade 2 self-assessment of oral health (
= 0.040) and better recovery courses were observed in patients with a grade 4 self-assessment (
= 0.0200). A worse recovery course was statistically significant more frequently in patients with previous oral surgical procedures (
= 0.019). Although we demonstrate that worse recovery outcomes were more frequent when certain bacteria were detected, there was no statistically significant difference. Further research is needed to identify microbial profiles specific to the development of worse outcomes after a third molar alveotomy.
Typically, a healthcare intervention is evaluated by comparing data before and after its implementation using statistical tests. Comparing group means can miss underlying trends and lead to erroneous ...conclusions. Segmented linear regression can be used to reveal secular trends but is susceptible to outliers. We described a novel method using segmented robust regression techniques to evaluate the effect of introducing a dedicated hip fracture unit (HFU).
We retrospectively analysed patient outcomes from a total of 2777 patients sustaining proximal femoral fragility fractures over a 6-year period at a Level 1 Major Trauma Centre. We compared time to surgical intervention and length of hospital stay before and after the implementation of the HFU using group comparison tests, segmented ordinary regression and robust regression techniques to evaluate the effect of the intervention.
Group comparison tests did not identify a significant difference in time to surgery pre and post- HFU. Segmented regression revealed that there was a significant reduction in time to surgery but that this predated the introduction of the HFU. Group comparison tests did not identify a significant difference in length of stay pre and post-HFU. Ordinary segmented regression demonstrated that there was a constant reduction in length of stay, which accelerated after the introduction of the HFU. Robust regression identified that this change occurred prior to the HFU.
There was a significant decrease in time to surgical intervention during the study period that occurred long before the introduction of the HFU, and that cannot be attributed to the HFU itself. Length of stay started dropping early in the study period and was unrelated to the HFU. However, with robust regression we concluded that the HFU was effective in reducing relatively long hospital stays (outliers).
Several explanatory factors that may have affected the observed trends in time to surgery and length of stay were identified.
Robust regression is a useful adjunct to ordinary segmented linear regression techniques in modelling retrospective time-series and dealing with outliers. The changes observed in hip fracture patient outcomes over a 6-year period was likely multifactorial.
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