Asymmetric Index Research Articles

Short‐Term Traffic Volume Forecasting with Asymmetric Loss Based on Enhanced KNN Method

Short‐term traffic volume forecasting is one of the most essential elements in Intelligent Transportation System (ITS) by providing prediction of traffic condition for traffic management and control applications. Among previous substantial forecasting approaches, K nearest neighbor (KNN) is a nonparametric and data‐driven method popular for conciseness, interpretability, and real‐time performance. However, in previous related researches, the limitations of Euclidean distance and forecasting with asymmetric loss have rarely been focused on. This research aims to fill up these gaps. This paper reconstructs Euclidean distance to overcome its limitation and proposes a KNN forecasting algorithm with asymmetric loss. Correspondingly, an asymmetric loss index, Imbalanced Mean Squared Error (IMSE), has also been proposed to test the effectiveness of newly designed algorithm. Moreover, the effect of Loess technique and suitable parameter value of dynamic KNN method have also been tested. In contrast to the traditional KNN algorithm, the proposed algorithm reduces the IMSE index by more than 10%, which shows its effectiveness when the cost of forecasting residual direction is notably different. This research expands the applicability of KNN method in short‐term traffic volume forecasting and provides an available approach to forecast with asymmetric loss.

Comparison of changes in shoulder functions between biceps tenotomy and tenodesis in an animal model

ObjectivesTenotomy and tenodesis of the long head of biceps tendon are effective pain-relieving treatments. However, there is no consensus on the functional outcome after these surgical procedures. We hypothesized that there would be no difference in ambulation parameters after recovery from the surgery between rats that underwent tenotomy versus tenodesis procedures. MethodsTwenty-four New Zealand rats were used and randomly divided into three groups. Each group received one of the following surgeries: tenotomy, tenodesis, and sham operation. A video-based walking track system was applied for gait analysis at day −1, 1, 3, 5, 7, 14 and 21 for each rat. Temporal and spatial parameters were obtained, and asymmetric index was calculated for each parameter. ResultsCompared to the tenotomy and sham-operated groups, the rats in the tenodesis group had shorter stance phase, longer swing time, longer step length, smaller paw length, smaller intermediary toe-spread length, smaller toe-spread length, and larger foot angle right after the tenodesis procedure. After day 14, all parameters were equivalent to those of the sham-operated group. At the end of the study, there were no functional changes found in tenotomy and tenodesis groups compared with the sham-operated group and preoperative status. ConclusionTransient functional alterations in temporal and spatial parameters are found after tenotomy and tenodesis in a rat model. The functional changes in the tenodesis group existed for a longer period than in tenotomy group; however, and all parameters showed no significant differences when compared with the sham group at the conclusion of the study.

Limiting thermal characteristics for flow of non-Newtonian fluids between asymmetrically heated parallel plates: An analytical study

In this work, an analytical study on the limiting thermal transport characteristics for the flow of a non-Newtonian fluid namely, power law liquid, between asymmetrically heated parallel plates is presented. The transport equations for mass, momentum, and energy are analytically solved to obtain closed-form expressions for the temperature distributions in the flow field and the limiting Nusselt number in terms of relevant parameters. The effects of frictional heating due to viscous dissipation on the heat transfer characteristics are studied. Results are presented in terms of degree of asymmetric heating, Brinkman number, and power law index. The most important finding from the present work is the nontrivial interplay between degree of asymmetric heating and the rheological behavior of the fluid in dictating the thermal transport characteristics of heat.

Correlation between Gait Asymmetry and Leg Length Discrepancy—What Is the Role of Clinical Abnormalities?

Reducing the effect of leg length discrepancy (LLD) on gait abnormalities while other abnormal conditions such as spasticity, joint contractures or weak muscle strength are exhibited is challenging. This study aimed to evaluate the impact of mild LLD on lower limb biomechanics, on participants with anatomic LLD with and without other clinical abnormalities. A motion capture system was utilized on 32 participants to measure lower limb kinematics and dynamic leg length (DLL) throughout the gait cycle, calculated as the absolute distance from the hip joint center, either to the heel, ankle joint center, or forefoot. The Pearson correlation coefficient found that LLD was associated with 5 kinematic variables only when LLD appeared with no other clinical abnormalities present (r = 0.574 – 0.846, p < 0.05). When clinical abnormalities were present, the random forest classification accuracy was lower (64% versus 80%), implying that the used kinematics are low predictors for anatomic LLD, revealing a higher asymmetrical clearance index (the difference between the maximal stance phase and the minimal contra-lateral swing phase DLL) and a different kinematic variable importance index. Clinical abnormalities in pathological gait will in all probability significantly affect gait deviations, affirming mild anatomic LLD as inconsequential. A functional measurement can offer a better estimate as to the side and extent of the functional discrepancy.

Distribution and activity pattern of stone marten Martes foina in relation to prey and predators

Small carnivores are expected to optimize their activity to maximize prey capture and minimize their encounter with predators. We assessed the activity pattern of the stone marten Martes foina in relation to its potential prey, the Himalayan woolly hare Lepus oiostolus and the Royle’s pika Ochotona roylei, and its predators, the red fox Vulpes vulpes and the free-ranging dog Canis familiaris. Using three years of camera trapping data from the Indian Trans-Himalaya, we estimated individual and pair-wise spatio-temporal niche width and overlap, respectively, using Levins’ asymmetric index. Stone martens showed limited space use (spatial niche width 0.16) and nocturnal activity (temporal niche width 0.35). They had high temporal (0.75) and low spatial overlap (0.05) with hares; while they had relatively low temporal (0.33) but higher spatial overlap (0.29) with pikas. Red foxes showed relatively high temporal (1.21) and spatial (0.75) overlap with martens, while free-ranging dogs showed low temporal (0.23) and spatial (0.03) overlap with martens. Although restricted space and time use by pikas might help martens track pikas even with relatively low spatio-temporal overlap, martens may be benefiting from higher temporal overlap with hares. While martens seem to be co-existing with foxes, their nocturnal activity might be driven by a trade-off between consuming prey and avoidance of diurnal predators like dogs.

Functional tractography of white matter by high angular resolution functional-correlation imaging (HARFI).

Functional magnetic resonance imaging with BOLD contrast is widely used for detecting brain activity in the cortex. Recently, several studies have described anisotropic correlations of resting-state BOLD signals between voxels in white matter (WM). These local WM correlations have been modeled as functional-correlation tensors, are largely consistent with underlying WM fiber orientations derived from diffusion MRI, and appear to change during functional activity. However, functional-correlation tensors have several limitations. The use of only nearest-neighbor voxels makes functional-correlation tensors sensitive to noise. Furthermore, adjacent voxels tend to have higher correlations than diagonal voxels, resulting in orientation-related biases. Finally, the tensor model restricts functional correlations to an ellipsoidal bipolar-symmetric shape, and precludes the ability to detect complex functional orientation distributions (FODs). We introduce high-angular-resolution functional-correlation imaging (HARFI) to address these limitations. In the same way that high-angular-resolution diffusion imaging (HARDI) techniques provide more information than diffusion tensors, we show that the HARFI model is capable of characterizing complex FODs expected to be present in WM. We demonstrate that the unique radial and angular sampling strategy eliminates orientation biases present in tensor models. We further show that HARFI FODs are able to reconstruct known WM pathways. Finally, we show that HARFI allows asymmetric "bending" and "fanning" distributions, and propose asymmetric and functional indices which may increase fiber tracking specificity, or highlight boundaries between functional regions. The results suggest the HARFI model could be a robust, new way to evaluate anisotropic BOLD signal changes in WM.

Sensing Characteristics of Helical Long-Period Gratings Written in the Double-Clad Fiber by CO2 Laser

We demonstrate the fabrication of helical long-period gratings (HLPGs) with the periodic helical index modulation by twisting the double-clad fiber (DCF) while the fiber was exposed by CO2 laser. Torsion, bending, surrounding refractive index, temperature and axial strain characteristics of the fabricated DCF-HLPG were investigated experimentally. The DCF-HLPG was found to have a high torsion sensitivity of −0.384 nm/(rad/m) and bending sensitivity of 18.112 nm/m−1 due to the asymmetric helical index modulation across the fiber section induced by the CO2 laser heating.

Optimum cross section index (OCI): a new approach for identification of an optimum channel—a case study of the Ichamati River, India

The Ichamati River drains the east and south side of the North 24 Parganas district which belongs to the Ganga-Brahmaputra Delta (GBD), covered by deep Quaternary sediments produced under tropical monsoon climate in India. The district is densely populated. The river has huge impact on its population. In this paper, particular attention has been paid to a new method, named optimum cross section index (OCI), which is a numerical representation of a river cross section with respect to its optimum condition. To establish the validity and reliability of OCI, as circumstantial evidences, we have measured and analyzed the geometric parameters, such as width, depth, hydraulic radius, wetted perimeter, and bank profile at 22 points, and applied the areal difference asymmetric index (ADAI). The paper considers that the changing characters of the geometric form of the cross sections and ADAI stand for the OCI. All the techniques reveal that (1) the area of channel decreases abruptly upstream downward, (2) the upstream channel is more symmetrical than the lower reach, and (3) the area of optimum channel gradually increases upstream downward. Results of the study show that the river is going to be deteriorating from upstream downward. OCI has been constructed based on width and depth, which are relatively easily available data. So, this model may be well assessable to identify the optimum channel for a river management.

Dual-Resonance-Coupling and Sensing Characteristics in an All-Solid Photonic Bandgap Fiber Interferometer Based on LP01 Cladding Supermodes

A dual-resonance-coupling phenomenon and the sensing characteristics of an in-fiber modal interferometer based on cascaded long period gratings inscribed in an all-solid photonic bandgap fiber are demonstrated. Theoretical and experimental investigations reveal that the dual-resonance dips result from the coupling between fundamental core mode and two different kinds of LP01 cladding supermodes. Due to the deep grooves and asymmetric index distribution along the long period grating caused by side illumination, this dual-resonance interferometer is sensitive to polarization and twist, and the dual-resonance dips according to different LP01 cladding supermodes exhibit different responses to twist. Furthermore, the transmission loss and the resonance wavelength of each interference dip show discrimination in sensitivities of temperature and twist, making it a good candidate for multiple physics parameters measurements.

Treatment outcome of bimaxillary surgery for asymmetric skeletal class II deformity.

Facial asymmetry is one of the main concerns in patients with a dentofacial deformity. The aims of the study were to (1) evaluate the changes in facial asymmetry after bimaxillary surgery for asymmetric skeletal class II deformity and (2) compare preoperative and postoperative facial asymmetry of class II patients with normal controls. The facial asymmetry was assessed for 30 adults (21 women and 9 men, mean age: 29.3years) who consecutively underwent bimaxillary surgery for asymmetric skeletal class II deformity using cone-beam computed tomography before and at least 6months after surgery. Thirty soft tissue and two dental landmarks were identified on each three-dimensional facial image, and the asymmetry index of each landmark was calculated. Results were compared with those of 30 normal control subjects (21 women and 9 men, mean age: 26.2years) with skeletal class I structure. Six months after surgery, the asymmetric index of the lower face and total face decreased significantly (17.8 ± 29.4 and 16.6 ± 29.5mm, respectively, both p < 0.01), whereas the asymmetric index of the middle face increased significantly (1.2 ± 2.2mm, p < 0.01). Postoperatively, 53% of the class II patients had residual chin asymmetry. The postoperative total face asymmetric index was positively correlated with the preoperative asymmetric index (r = 0.37, p < 0.05). Bimaxillary surgery for patients with asymmetric class II deformity resulted in a significant improvement in lower face asymmetry. However, approximately 50% of the patients still had residual chin asymmetry. The total face postoperative asymmetry was moderately related to the initial severity of asymmetry. These findings could help clinicians better understand orthognathic outcomes on different facial regions for patients with asymmetric class II deformity.

Analysis of Bloch Surface Waves at the Interface Between Two Semi-infinite Rugate Filters with Symmetric Refractive Index Profiles

Surface electromagnetic waves are representation of Maxwell’s frequency domain equations at the interface of two dissimilar materials. In this article, two canonical boundary value problems have been formulated to analyze the multiplicity of electromagnetic surface waves at the interface between two dissimilar materials. In the first problem, interface between two semi-infinite rugate filters having symmetric refractive index profiles is considered and in the second problem, to enhance the multiplicity of surface electromagnetic waves, a homogeneous dielectric slab is included between two semi-infinite symmetric rugate filters. Multiplicity has been observed by varying the size of dielectric material from 0 to 1000 nm. Numerical results show that the number of Tamm waves of different phase speeds, different polarization states, different degrees of localization, and different field profiles that are being propagated at interface between two semi-infinite rugate filters having symmetric refractive profile is almost twice as when asymmetric refractive index profile is used. Having two interfaces when a homogeneous dielectric layer is placed between two semi-infinite rugate filters has increased the multiplicity of electromagnetic surface waves.

Explaining the Year‐to‐Year Variability of the Eastern Pacific Intertropical Convergence Zone in the Boreal Spring

AbstractThe year‐to‐year variability of the Intertropical Convergence Zone (ITCZ) in the eastern tropical Pacific is a significant phenomenon of the tropical climate system. Asymmetric interannual variation of precipitation on two sides of the Equator is often observed there in the boreal spring. We introduce a simple normalized asymmetric index and a double ITCZ index as well as a hierarchical clustering method to describe the ITCZ variation based on the tropical boreal spring precipitation from 1979 to 2017. We show that the indices and the clustering method give consistent categorization of asymmetric ITCZ variation. We find that the asymmetry of precipitation can be explained by the remote impact of the interannual variability of the central Pacific sea surface temperature (SST) on the horizontal gradient of surface pressure and surface wind convergence, especially the Modoki mode. The central Pacific SST also remotely modulates free‐tropospheric temperature and vertical stability in the eastern equatorial Pacific, but this remote impact is secondary to the wind convergence. Interannual variability of local SST south of the Equator plays little role in the precipitation variability, which is supported by numerical experiments with a regional atmospheric model. Results imply that surface wind convergence should be considered in convection schemes to improve the simulation of precipitation in the eastern tropical Pacific in climate models.

Improvement in the measurement error of the specific binding ratio in dopamine transporter SPECT imaging due to exclusion of the cerebrospinal fluid fraction using the threshold of voxel RI count.

In Japan, the Southampton method for dopamine transporter (DAT) SPECT is widely used to quantitatively evaluate striatal radioactivity. The specific binding ratio (SBR) is the ratio of specific to non-specific binding observed after placing pentagonal striatal voxels of interest (VOIs) as references. Although the method can reduce the partial volume effect, the SBR may fluctuate due to the presence of low-count areas of cerebrospinal fluid (CSF), caused by brain atrophy, in the striatal VOIs. We examined the effect of the exclusion of low-count VOIs on SBR measurement. We retrospectively reviewed DAT imaging of 36 patients with parkinsonian syndromes performed after injection of 123I-FP-CIT. SPECT data were reconstructed using three conditions. We defined the CSF area in each SPECT image after segmenting the brain tissues. A merged image of gray and white matter images was constructed from each patient's magnetic resonance imaging (MRI) to create an idealized brain image that excluded the CSF fraction (MRI-mask method). We calculated the SBR and asymmetric index (AI) in the MRI-mask method for each reconstruction condition. We then calculated the mean and standard deviation (SD) of voxel RI counts in the reference VOI without the striatal VOIs in each image, and determined the SBR by excluding the low-count pixels (threshold method) using five thresholds: mean-0.0SD, mean-0.5SD, mean-1.0SD, mean-1.5SD, and mean-2.0SD. We also calculated the AIs from the SBRs measured using the threshold method. We examined the correlation among the SBRs of the threshold method, between the uncorrected SBRs and the SBRs of the MRI-mask method, and between the uncorrected AIs and the AIs of the MRI-mask method. The intraclass correlation coefficient indicated an extremely high correlation among the SBRs and among the AIs of the MRI-mask and threshold methods at thresholds between mean-2.0D and mean-1.0SD, regardless of the reconstruction correction. The differences among the SBRs and the AIs of the two methods were smallest at thresholds between man-2.0SD and mean-1.0SD. The SBR calculated using the threshold method was highly correlated with the MRI-SBR. These results suggest that the CSF correction of the threshold method is effective for the calculation of idealized SBR and AI values.

Bilateral asymmetry of skin temperature is not related to bilateral asymmetry of crank torque during an incremental cycling exercise to exhaustion.

Although moderate relationships (|r| ∼ 0.5) were reported between skin temperature and performance-related variables (e.g., kinetic), it remains unclear whether skin temperature asymmetry reflects muscle force imbalance in cycling. Therefore, the aim of this study was to assess whether a relationship exists between kinetic and thermal asymmetry during a fatiguing exercise. Ten elite cyclists were enrolled and tested on a maximal incremental cycling test. Peak crank torques of both legs were obtained at the initial and final workload. Likewise, bilateral skin temperatures were recorded before and after exercise. Asymmetric indexes were also calculated for kinetic (AIK) and skin temperature (AIT) outcomes. The bilateral peak crank torques showed a larger difference at the final compared to the initial workload (p < 0.05) of the incremental exercise. Conversely, the bilateral skin temperature did not show any differences at both initial and final workload (p > 0.05). Additionally, trivial relationships were reported between AIK and AIT (−0.3 < r < 0.2) at the initial and final workload. The obtained results showed that changes in bilateral kinetic values did not reflect concurrent changes in bilateral skin temperatures. This finding emphasizes the difficulty of associating the asymmetry of skin temperature with those of muscle effort in elite cyclists. Lastly, our study also provided further insights on thermal skin responses during exhaustive cycling exercise in very highly-trained athletes.

ОСОБЛИВОСТІ ПРОСТОРОВИХ РОЗМІРІВ ВЕРХНЬОЩЕЛЕПНИХ ПАЗУХ У ОСІБ ЧОЛОВІЧОЇ ТА ЖІНОЧОЇ СТАТІ ЗРІЛОГО ВІКУ ЗГІДНО З РЕКОНСТРУЙОВАНИМИ 3Д МОДЕЛЯМИ

The analysis of 102 Cone-beam Computed Tomography of the nose and paranasal sinuses was performed. Spatial dimensions of the maxillary sinuses according to the 3D models, their symmetry, as well as natural ostiums openings passability in relation to the forms of maxillary sinuses (MS) have been determined. Analysis of the 3D models of MS results. 102 examined subjects of different periods of mature age males and females showed, that the volume of sinuses varies from 9.7 cm3 (min) to 33.2 cm3 (max) and has a pronounced age and gender dependence. In the first age group, namely in the early mature age (from the age of 21 to 35), the spatial volumes are higher in men – 22.8 ± 2.09 cm³ and 23.06 ± 1.93 cm³ respectively, on the left and right sides, and in women, the scores are lower – 18 ± 1.91 cm³ for the left sinus and 17.06 ± 1.8 cm for the right sinus. In the case of the late mature age group (36 to 60 years), the average volume of MS in men is 21 ± 2,09 cm³ and 22,13 ± 2,4 cm³, whereas in women it is 21,42 ± 2 , 42 cm³ and 20.78 ± 2.28 cm³ respectively for the left and right sides. Gender comparison of individual indicators of the size of the left MS in early mature age showed, that the volume of the left MS in men is bigger than in women of this age group. In the late mature age, the volume of the left MS is higher in females than in males. The analysis of individual indicators of the size of the right MS in early mature age showed, that the volume of the right MS, as well as left, in men is bigger than in women of this age group. In the late mature age, the volume of the right MS, unlike the left, is larger in men than in women. The conducted analysis of age dynamics of the volume of maxillary sinuses in individuals of different periods of mature age has shown that the researched indicator in both women and men in both age groups is asymmetrical. At the same time, the volume of both maxillary sinuses in men with age decreases, and in women – increases. It was also established that the volume of the left MS in persons of the first age group and the right MS in both age groups is higher than in men, and the volume of the left MS in the second age group is slightly higher among the female population. The analysis of symmetry of sinuses has shown, that maxillary sinuses symmetry was observed in 34 patients (33% of the total number of all surveyed), and asymmetry – in 68 patients (67%). The analysis of the symmetry of the MS in women and men made it possible to establish that in women the difference between the investigated parameter is insignificant – the symmetry of the indicator of the MS volume was established in 55% of the examined women, asymmetry – in 45%. Unlike women, in men the asymmetry of the MS is found to be much higher – 81% of asymmetric indices with 19% of the symmetrical total of the examined male population. The analysis of computed tomographies allowed to determine the influence of the form of maxillary sinuses on the passability of their natural ostium openings. According to the results, we often see the passage of the natural ostiums of the sinuses in the circular form of the MS, in particular, in the horizontal projection – in 100% of the examined. Also, often natural ostiums openings are passable in rectangular, triangular and oval forms of sinuses. In the square form, the passability of natural ostiums of the MS observed the least – only in 25% of cases.

Monitoring cerebral blood flow change through use of arterial spin labelling in acute ischaemic stroke patients after intra-arterial thrombectomy.

To evaluate the ability of arterial spin labelling perfusion-weighted imaging (ASL-PWI) to identify reperfusion status and to predict the early neurological outcome of acute ischaemic stroke patients after intra-arterial (IA) thrombectomy. A total of 51 acute ischaemic stroke patients who underwent IA thrombectomy were retrospectively reviewed. Asymmetrical index before and after IA thrombectomy (AICBFpre and AICBFpost) and volume ratio of the reperfused territory to the baseline perfusion abnormality (reperfusion volume ratio) were calculated on ASL-PWI. A paired t-test was used to compare AICBFpre and AICBFpost. Pearson correlation and multiple linear regression were performed to evaluate correlations between the imaging parameters and NIHSS scores. Mean AICBFpost was significantly higher than mean AICBFpre (0.923±0.352 vs. 0.312±0.191, p<0.001). AICBFpre had a significant correlation with NIHSSpre (pr=-0.430, p=.004). ∆AICBF had significant correlations with NIHSS24 h, NIHSS5-7 days and ∆NIHSS5-7 days (r=-0.356, p=0.028; r=-0.597, p<0.001; r=-0.346, p=0.033, respectively). ∆AICBF, reperfusion volume ratio and baseline infarct volume were significant independent predictors for NIHSS5-7 days. ASL-PWI has the potential to serve as a non-invasive imaging tool to monitor the reperfusion status and predict the early neurological outcome of acute ischaemic stroke patients after IA thrombectomy. • CBF change on ASL-PWI after IA thrombectomy correlated with NIHSS scores. • ASL-PWI can non-invasively monitor reperfusion in AIS patients after IA thrombectomy. • ASL-PWI may predict early outcome of AIS patients after IA thrombectomy.

Dynamics of a broad-band quantum cascade laser: from chaos to coherent dynamics and mode-locking.

The dynamics of a multimode quantum cascade laser, are studied in a model based on effective semiconductor Maxwell-Bloch equations, encompassing key features for the radiation-medium interaction such as an asymmetric frequency dependent gain and refractive index as well as the phase-amplitude coupling provided by the linewidth enhancement factor. By considering its role and that of the free spectral range, we find the conditions in which the traveling wave emitted by the laser at the threshold can be destabilized by adjacent modes, thus leading the laser emission towards chaotic or regular multimode dynamics. In the latter case our simulations show that the field oscillations are associated to self-confined structures which travel along the laser cavity, bridging mode-locking and solitary wave propagation. In addition, we show how a RF modulation of the bias current leads to active mode-locking yielding high-contrast, picosecond pulses. Our results compare well with recent experiments on broad-band THz-QCLs and may help in the understanding of the conditions for the generation of ultrashort pulses and comb operation in mid-IR and THz spectral regions.

Crossed Cerebellar Diaschisis: Risk Factors and Correlation to Functional Recovery in Intracerebral Hemorrhage.

ObjectiveThe purpose of this study is to investigate predictors of crossed cerebellar diaschisis (CCD), and the effects of CCD on functional outcomes including motor function, activities of daily living, cognitive function, and ambulation 6 months after onset in patients with intracerebral hemorrhage (ICH).MethodsA total of 74 patients experiencing their first ICH were recruited. If the asymmetric index was more than 10% using single photon emission computed tomography (SPECT), a diagnosis of CCD was confirmed. Clinical factors were retrospectively assessed by reviewing medical records. Radiologic factors encompassed the concomitance of intraventricular hemorrhage, side and location of the lesion, and hemorrhage volume. Functional outcomes were evaluated using the Fugl-Meyer Assessment, the Korean version of the Mini-Mental State Examination, the Korean version of the Modified Barthel Index, and measurement of the Functional Ambulatory Category at the time of SPECT measurement and 6 months post-ICH.ResultsLesion location, especially in the basal ganglia (odds ratio [OR]=6.138, p=0.011), and hemorrhagic volume (OR=1.055, p=0.046) were independent predictors for CCD according to multivariate logistic regression analysis. In addition, the presence of CCD was significantly related to the improvement in Fugl-Meyer Assessment score after 6 months (adjusted R2=0.152, p=0.036).ConclusionLesion location and hemorrhagic volume were the predisposing factors for CCD, and the CCD was associated with poor motor recovery over 6 months in patients with hemorrhagic stroke.

GaN/AlGaN photonic crystal narrowband thermal emitters on a semi-transparent low-refractive-index substrate

We demonstrate a GaN/AlGaN photonic crystal thermal emitter supported by a semi-transparent low-refractive-index substrate for mid-wavelength infrared operation. The employment of the substrate increases the mechanical strength of the photonic crystal, and enables the fabrication of a large-area thermal emitter for high power operation. First, we numerically investigate the control of emission spectra of the GaN/AlGaN photonic crystal thermal emitters and found that nearly single-peak emission in the normal direction can be realized in spite of the lower and asymmetric refractive index contrast due to the existence of the substrate. Then we fabricate a GaN/AlGaN thermal emitter with an area of 3.4 mm × 3.4 mm on a sapphire substrate, and experimentally demonstrate narrowband thermal emission with a Q factor of 101 and an emission power of 25 mW/μm/sr at 800°C.

Effects of free stream flow turbulence on blowoff characteristics of bluff-body stabilized premixed flames

In this article we report on an experimental investigation of a bluff-body stabilized lean premixed flame subjected to different levels of free stream turbulence intensities (4, 14, 24 and 30%) at conditions approaching blowoff. The mean flow velocities ranged from 5 to 15 m/s. The turbulence Reynolds number based on integral length scale and rms velocity ranged from 44 to 4280. Simultaneous imaging of hydroxyl (OH) and formaldehyde (CH2O) by planar laser induced fluorescence and particle image velocimetry (PIV) was used to study the interaction between the flame and the flow field and determine the sequence of events leading to flame blowoff. CH2O fluorescence and the pixel-by-pixel multiplication of OH and CH2O fluorescence signals were utilized to mark the preheat and heat release regions of flame front respectively. The flame structure was observed to be strongly modified by the turbulent flow field which affects the lean blowoff limits. The flame blowoff equivalence ratio increased with increasing free stream turbulence levels owing to strong interactions of the turbulent flow with the flame and the resulting modification of flame surfaces and ensuing local flame extinction. For stably burning flames, the flame front predominantly enveloped the shear layer vortices for all the turbulent conditions. As blowoff was approached, the flame front and shear layer vortices entangled inducing high local strain rates on the flame front that exceed the extinction strain resulting in significant breaks along the reaction zone. At conditions near blowoff, wide regions of CH2O and heat release were observed inside the recirculation zone. Velocity vectors near the flame holes indicate the penetration of the reactants into the recirculation zone. Several properties were measured to characterize the near blowoff flames which include the strain rate and curvature statistics along the flame front, burning fraction, asymmetric index and the average duration of the blowoff event.