Exploration of the Correlation Between GRHL1 Expression and Tumor Microenvironment in Endometrial Cancer and Immunotherapy.

Introduction: GRHL1 belongs to the family of Grainyhead-like (GRHL). Previous studies have shown that dysregulation of growth and survival pathways is associated with the GRHL family of gene cancers. Immunotherapy with checkpoint inhibitors has changed the treatment paradigm for many tumors, including endometrial cancer (EC). However, the effect of GRHL1 on immunotherapy in EC and its relationship with immune cell infiltration are poorly understood. Methods: Differential expression of GRHL1 between EC and normal EC tissues was analyzed by searching the TCGA database, and the results were verified utilizing immunohistochemistry analyses. Next, the relationship between GRHL1, CD8+ T cells and tumor microenvironment (TME) was also investigated, and the effect of GRHL1 expression on immunotherapy in EC was evaluated. Results: According to the findings, EC tissues had elevated expression levels of GRHL1 relative to normal tissues. Patients with EC who expressed GRHL1 at high levels experienced worse overall survival (OS) and Progression-free survival (PFS) than those whose expression was lower. In addition, GRHL1 expression was negatively correlated with CD8+ T cells, and patients with high GRHL1 expression were less effective in receiving immunotherapy. Conclusion: The expression of GRHL1 was high in EC patients, and high expression of GRHL1 inhibits the proliferation of CD8+ T cells in the tumor microenvironment of EC and affect the efficacy of immunotherapy.

Receptor-interacting protein kinase 1 (RIPK1) regulates cervical cancer cells via NF-κB-TNF-α pathway: An in vitro study.

INTRODUCTION: Cervical cancer (CC) is associated with high morbidity and mortality rates in women. Members of the receptor-interacting protein kinase (RIPK) family are important regulators of inflammation and cell death. However, the characteristics, molecular functions, and expression mechanisms of RIPK1 in CC remain unclear. MATERIAL AND METHODS: To determine whether RIPK1 can be used for targeted therapy of CC, we assessed the clinical importance, biological function, and potential impact of RIPK1 in CC in 50 patients with CC. We utilized immunohistochemical staining, transfection, western blotting, cell counting kit-8 assay, colony formation assay, and wound healing assays among others, to elucidate the role of RIPK1 in CC. RESULTS: RIPK1 expression was higher in tumor tissues than in paracancerous tissues. Poor prognosis of CC was linked to RIPK1 upregulation. Furthermore, silencing RIPK1 significantly inhibited the proliferation, migration, and invasion of CC cells in vitro. We also established that RIPK1 increased cell migration, invasion, and multiplication by regulating nuclear factor kappa-B (NF-κB) and tumor necrosis factor (TNF). DISCUSSION: RIPK1 activates NF-κB and regulates TNF release to enhance the proliferation and spread of CC cells while suppressing their apoptosis. Therefore, RIPK1 plays a key role in the formation and progression of CC and is a potential target for CC treatment.

Effects of moderate alcohol levels on default mode network connectivity in heavy drinkers.

BACKGROUND: It is well established that even moderate levels of alcohol affect cognitive functions such as memory, self-related information processing, and response inhibition. Nevertheless, the neural mechanisms underlying these alcohol-induced changes are still unclear, especially on the network level. The default mode network (DMN) plays an important role in memory and self-initiated mental activities; hence, studying functional interactions of the DMN may provide new insights into the neural mechanisms underlying alcohol-related changes. METHODS: We investigated resting-state functional connectivity (rsFC) of the DMN in a cohort of 37 heavy drinkers at a breath alcohol concentration of 0.8 g/kg. Alcohol and saline were infused in a single-blind crossover design. RESULTS: Intranetwork connectivity analyses revealed that participants showed significantly decreased rsFC of the right hippocampus and right middle temporal gyrus during acute alcohol exposure. Moreover, follow-up analyses revealed that these rsFC decreases were more pronounced in participants who reported stronger craving for alcohol. Exploratory internetwork connectivity analyses of the DMN with other resting-state networks showed no significant alcohol-induced changes, but suffered from low statistical power. CONCLUSIONS: Our results indicate that acute alcohol exposure affects rsFC within the DMN. Functionally, this finding may be associated with impairments in memory encoding and self-referential processes commonly observed during alcohol intoxication. Future resting-state functional magnetic resonance imaging studies might therefore also investigate memory function and test whether DMN-related connectivity changes are associated with alcohol-induced impairments or craving.

Deep Gray Matter Iron Deposition and Its Relationship to Clinical Features in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy Patients: A 7.0-T Magnetic Resonance Imaging Study.

Background and Purpose- Distribution patterns of iron deposition in deep gray matter and their association with clinical characteristics in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) remain unclear. We aimed to evaluate iron deposition in deep gray matter in patients with CADASIL using 7.0-T susceptibility-weighted imaging and mapping and to explore its correlations with clinical characteristics. Methods- Thirty-nine patients with CADASIL, confirmed via genetic analysis or skin biopsy, were enrolled. We examined patients using the Mini-Mental State Examination, modified Rankin Scale, and brain 7.0-T magnetic resonance imaging and obtained magnetic resonance imaging lesion loads, small vessel disease scores, and susceptibility mapping. The following regions of interest were selected: caudate nucleus, putamen, globus pallidus, thalamus, substantia nigra, and red nucleus. The quantitative differences in the susceptibility of deep gray matter between the CADASIL and control groups and the correlations between deep gray matter susceptibility and clinical characteristics were identified. Results- Compared with the control group, the CADASIL group showed significantly increased susceptibility of caudate nucleus, putamen, thalamus, substantia nigra, and red nucleus. The susceptibility of deep gray matter in basal ganglia region, including caudate nucleus, putamen, and thalamus, significantly increased with age or disease duration and positively correlated with small vessel disease scores in patients with CADASIL. Moreover, the susceptibility of thalamus positively correlated with modified Rankin Scale scores after adjusting for age and disease duration and that of putamen negatively correlated with Mini-Mental State Examination scores in patients with CADASIL after adjusting for age. Conclusions- Our findings indicate an association between abnormal iron deposition in deep gray matter of patients with CADASIL and their clinical characteristics. Therefore, excess iron deposition in deep gray matter, as indicated by 7.0-T susceptibility-weighted imaging and mapping, might not only be a novel magnetic resonance imaging feature but also a potential biomarker for CADASIL severity.

Reduced Venous Oxygen Saturation Associates With Increased Dependence of Patients With Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy: A 7.0-T Magnetic Resonance Imaging Study.

Background and Purpose- Accumulating evidence has demonstrated hemodynamic abnormalities and cerebral hypoperfusion in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Increased venous susceptibility assessed by susceptibility weighted imaging and mapping has been shown to indicate a decrease in venous oxygen saturation. This study aimed to investigate whether altered venous oxygen saturation is related to clinical phenotypes of CADASIL patients. Methods- Using 7.0-T susceptibility weighted imaging and mapping, we compared venous susceptibility of cortical veins between 41 CADASIL patients and 43 age- and sex-matched healthy controls. The magnetic resonance imaging lesion load, mini-mental state examination score, Barthel Index, and modified Rankin Scale were examined in the patient group, and the correlations between venous susceptibility and clinical characteristics were analyzed. Results- Venous susceptibility increased with age (r=0.508, P=0.001) and was higher in CADASIL patients than in healthy controls (t=-4.673; P<0.001). We found a positive association between venous susceptibility and the age-related white matter change scores (r=0.364; P=0.019), number of lacunar infarctions (r=0.520; P<0.001), number of cerebral microbleeds (ρ=0.445; P=0.004), and small-vessel disease scores (ρ=0.465; P=0.002) in CADASIL patients. Moreover, increased venous susceptibility was associated with higher modified Rankin Scale scores in CADASIL patients after adjustment for age- and small-vessel disease scores (odds ratio=3.178; 95% CI, 1.101-9.179; P=0.033). Conclusions- Our findings indicate that extensive cerebral hypoperfusion may induce central nervous system impairment in CADASIL, and susceptibility weighted imaging and mapping could be used clinically to assess the condition of CADASIL patients.

Lenticulostriate Arteries and Basal Ganglia Changes in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy, a High-Field MRI Study.

Background and Purpose: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) mainly affects the cerebral small arteries. We aimed to analyze changes in the lenticulostriate arteries (LSAs) and the basal ganglia in patients with CADASIL using high-field magnetic resonance imaging (7.0-T MRI). Methods: We examined 46 patients with CADASIL and 46 sex- and age-matched healthy individuals using 7.0-T MRI. The number and length of the LSAs, and the proportion of discontinuous LSAs were compared between the two groups. The Mini-Mental State Examination score, the modified Rankin Scale, the Barthel Index, and the MRI lesion load of the basal ganglia were also examined in patients with CADASIL. We analyzed the association between LSA measurements and the basal ganglia lesion load, as well as the association between LSA measurements and clinical phenotypes in this patient group. Results: We observed a decrease in the number of LSA branches (t = -2.591, P = 0.011), and an increase in the proportion of discontinuous LSAs (z = -1.991, P = 0.047) in patients with CADASIL when compared with healthy controls. However, there was no significant difference in the total length of LSAs between CADASIL patients and healthy individuals (t = -0.412, P = 0.682). There was a positive association between the number of LSA branches and the Mini-Mental State Examination scores of CADASIL patients after adjusting for age and educational level (ß = 0.438; 95% CI: 0.093, 0.782; P = 0.014). However, there was no association between LSA measurements and the basal ganglia lesion load among CADASIL patients. Conclusions: 7.0-T MRI provides a promising and non-invasive method for the study of small artery damage in CADASIL. The abnormalities of small arteries may be related to some clinical symptoms of CADASIL patients such as cognitive impairment. The lack of association between LSA measurements and the basal ganglia lesion load among the patients suggests that changes in the basal ganglia due to CADASIL are caused by mechanisms other than anatomic narrowing of the vessel lumen.

Current status and potential application of navigated transcranial magnetic stimulation in neurosurgery: a literature review.

Transcranial magnetic stimulation (TMS) is a noninvasive neurophysiologic technique that can stimulate the human brain. Positioning of the coil was often performed based merely on external landmarks on the head, meaning that the anatomical target in the cortex remains inaccurate. Navigated transcranial magnetic stimulation (nTMS) combines a frameless stereotactic navigational system and TMS coil and can provide a highly accurate delivery of TMS pulses with the guidance of imaging. Therefore, many novel utilities for TMS could be explored due to the ability of precise localization. Many studies have been published, which indicate nTMS enables presurgical functional mapping. This review aimed to provide a comprehensive literature review on nTMS, especially the principles and clinical applications of nTMS. All articles in PubMed with keywords of "motor mapping," "presurgical mapping," "navigated transcranial magnetic stimulation," and "language mapping" published from 2000 to 2018 were included in the study. Frequently cited publications before 2000 were also included. The most valuable published original and review articles related to our objective were selected. Motor mapping of nTMS is validated to be a trustful tool to recognize functional areas belonging to both normal and lesioned primary motor cortex. It can offer reliable mapping of speech and motor regions at cortex prior to operation and has comparable accuracy as direct electrical cortical stimulation. nTMS is a powerful tool for mapping of motor and linguistic function prior to operation, has high application value in neurosurgery and the treatment of neurological and psychiatric diseases, and has gained increasing acceptance in neurosurgical centers across the world.

Clinical application of 3.0 T intraoperative magnetic resonance combined with multimodal neuronavigation in resection of cerebral eloquent area glioma.

Glioma is the most common tumor among central nervous system tumors; surgical intervention presents difficulties. This is especially the case for gliomas in so-called "eloquent areas," as surgical resection threatens vital structures adjacent to the tumor. Intraoperative magnetic resonance imaging (iMRI) combined with multimodal neuronavigation may prove beneficial during surgery. This study explored the applicability of 3.0 T high field iMRI combined with multimodal neuronavigation in the resection of gliomas in eloquent brain areas.We reviewed 40 patients with a glioma located in the eloquent brains areas who underwent treatment in the Neurosurgery Department of Peking University International Hospital between December 2015 and August 2017. The experimental group included 20 patients treated using iMRI assistance technology (iMRI group). The remaining 20 patients underwent treatment by conventional neuronavigation (non-iMRI group). Tumor resection degree, preoperative and postoperative ability of daily living scale (Barthel index), infection rate, and operative time were compared between the 2 groups.No difference in infection rate was observed between the 2 groups. However, compared with the non-iMRI group, the iMRI group had a higher resection rate (96.55 ±â€Š4.03% vs 87.70 ±â€Š10.98%, P = .002), postoperative Barthel index (90.75 ±â€Š12.90 vs 9.25 ±â€Š16.41, P = .018), as well as a longer operation time (355.85 ±â€Š61.40 vs 302.45 ±â€Š64.09, P = .011).The use of iMRI technology can achieve a relatively higher resection rate among cases of gliomas in eloquent brain areas, with less incidence of postoperative neurological deficits. Although the operative time using iMRI was longer than that taken to perform conventional navigation surgery, the surgical infection rate in these 2 procedures showed no significant difference.

Prefrontal dysconnectivity links to working memory deficit in first-episode schizophrenia.

Working memory (WM) deficit is a core feature of schizophrenia and is characterized by abnormal functional integration in the prefrontal cortex, including the dorsolateral prefrontal cortex (dLPFC), dorsal anterior cingulate cortex (dACC), and ventrolateral prefrontal cortex (vLPFC). However, the specific mechanism by which the abnormal neuronal circuits that involve these brain regions contribute to this deficit is still unclear. Therefore, this study focused on these regions and sought to answer which abnormal causal relationships in these regions can be linked to impaired WM in schizophrenia. We used spectral dynamic causal modeling to estimate directed (effective) connectivity between these regions based on resting-state functional magnetic resonance imaging data from healthy control (HC) subjects and patients with first-episode schizophrenia (FES). By comparing these effective connections in the controls and patients, we found that the effective connectivity from the dACC to the dLPFC and from the right dLPFC to the left vLPFC was weaker in the FES group than in the HC group. Furthermore, these effective connections displayed a positive correlation with WM performance in the HCs. However, in the FES patients, the effective connectivity from the dACC to the dLPFC was not correlated with WM performance, and the effective connectivity from the right dLPFC to the left vLPFC was negatively correlated with WM performance. These results could be explained by an aberrant top-down mechanism of WM processing and provide new evidence for the dysconnectivity hypothesis of schizophrenia.

Study of Enhanced Depth Imaging Optical Coherence Tomography in Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary small artery disease caused by NOTCH3 gene mutation. We performed enhanced depth imaging optical coherence tomography (EDI-OCT) to evaluate the retinal vessel changes in CADASIL patients and assessed their consonance with brain magnetic resonance imaging (MRI) findings. METHODS: Of 27 genetically confirmed patients and an equal number of controls were recruited at the Peking University First Hospital from January 2015 to August 2016. All patients underwent 7T-MRI of the brain. Fazekas score, number of small infarcts and microbleeds were evaluated. All patients and controls underwent EDI-OCT to measure subfoveal choroidal thickness (SFCT), inner and outer diameters as well as arterial and venous wall thickness, and arterial venous ratio of the inner (AVRin) and outer diameters (AVRout). The relation between retinal vessel changes and Fazekas scores, numbers of small infarcts, or microbleeds was analyzed. Paired t-test was used to compare the SFCT and retinal vessel measurement data between patients and controls. Spearman's correlation was used to investigate the correlation between retinal vessel changes and MRI lesions. RESULTS: In CADASIL patients, mean SFCT (268.37 ± 46.50 µm) and mean arterial inner diameter (93.46 ± 9.70 µm) were significantly lower than that in controls (P < 0.001,P = 0.048, respectively). Mean arterial outer diameter (131.74 ± 10.87 µm), venous inner (128.99 ± 13.62 µm) and outer diameter (164.82 ± 14.77 µm), and mean arterial (19.13 ± 1.85 µm) and venous (17.91 ± 2.76 µm) wall thickness were significantly higher than that in controls (P = 0.023,P = 0.004,P < 0.001,P < 0.001, respectively). Arterial inner diameter (rs= -0.39, P= 0.044), AVRin (rs= -0.65,P < 0.001), and AVRout (rs= -0.56, P= 0.002) showed a negative correlation with the number of small infarcts. Venous inner diameter (rs = 0.46, P= 0.016) showed a positive correlation with the number of small infarcts. Venous inner diameter (rs = 0.59, P= 0.002), outer diameter (rs = 0.47, P= 0.017), showed a positive correlation with the number of cerebral microbleeds (CMBs). AVRin (rs= -0.52, P= 0.007) and AVRout (rs= -0.40, P= 0.048) showed a negative correlation with the number of CMBs. CONCLUSIONS: Measurement of retinal vessels using EDI-OCT correlates moderately well with MRI parameters. EDI-OCT might be a useful evaluation tool for CADASIL patients.

Angle- and polarization-dependent spectral characteristics of circular grating filters.

We design and implement one type of guided mode resonance (GMR) circular grating filters (CGFs) on an HfO2-on-silicon platform. Taking advantage of an angle-resolved micro-reflection measurement system, we achieve their incident angle- and polarization-dependent reflection spectra. For normal incident arbitrary linear polarization, a pair of reflection peaks is experimentally observed due to the coexistence of the azimuthal component Ea and the radial component Er of the incident wave electric field (E-field). For oblique incident s-polarization (E-field perpendicular to the incident plane), the peak excited by the Ea component splits into two sub-peaks due to the removal of degeneracy, while that excited by the Er component gradually fades away with the increase of the incident angle. For oblique incident p-polarization (E-field parallel to the incident plane), the spectrum appears to be reversed; that is, the peak corresponding to the Er component gets split while that corresponding to the Ea component gradually disappears when the incident angle increases. Moreover, we experimentally demonstrate the spectral relationships between CGFs and linear grating filters under not only normal incidence but also oblique incidence; these relationships greatly facilitate the spectral design and tailoring of the CGFs.

Association of maximum standardized uptake value with occult mediastinal lymph node metastases in cN0 non-small cell lung cancer.

OBJECTIVES: The management of non-small cell lung cancer (NSCLC) relies on the tumour-node-metastasis (TNM) stage, and the treatment regimen differs based on the N status. Positron emission tomography-computed tomography (PET-CT) has emerged as a powerful imaging tool for the detection of various cancers with a relatively low false-negative rate. We explored predictors to identify false-negative N2 disease in PET-CT. METHODS: A total of 284 consecutive cN0 patients with peripheral NSCLC who underwent PET-CT scans followed by curative intent resections were enrolled as a training set to identify predictors of occult N2 metastases by multivariable analysis. The accuracy and cut-off values for the predictors were calculated using a receiver operating characteristic curve. Clinical and pathological data were analysed retrospectively. An additional 151 patients were collected as a test set to validate the results, including the occult N2 rate and accuracy. RESULTS: In total, 8.5% (24/284) PET-CT-diagnosed N0 NSCLC cases had pathologically diagnosed N2 metastases. The SUVmax of the primary tumour was a unique independent risk factor for occult N2 NSCLC [P = 0.003, 95% confidence interval = 0.81-0.96, odds ratio (OR) = 0.88]. Occult N2 metastases occurred more frequently in the subcarinal (16/24) and right lower paratracheal lymph nodes (12/24). Accordingly, we divided the patients into two groups by SUVmax: the occult N2 rates in the SUVmax of <2.6 and SUVmax of ≥2.6 groups were 1.0% (1/100) and 12.5% (23/184), respectively (P = 0.001). In the test set, the occult N2 incidence rate was 9.3% (14/151), with the highest rates occurring in the subcarinal (9/14) and right lower paratracheal lymph nodes (6/14). In the two groups defined by SUVmax, the occult N2 rates were 4% (2/50) and 11.9% (12/101), respectively. CONCLUSIONS: The SUVmax of the primary tumour was an independent risk factor for occult N2 metastases in NSCLC patients diagnosed as clinical N0 by PET-CT. SUVmax of ≥2.6 of the primary tumour may indicate the risk of N2 metastases, and invasive mediastinal staging techniques or comprehensive therapy should not be ignored in these patients.

Resting-State Coupling between Core Regions within the Central-Executive and Salience Networks Contributes to Working Memory Performance.

Previous studies investigated the distinct roles played by different cognitive regions and suggested that the patterns of connectivity of these regions are associated with working memory (WM). However, the specific causal mechanism through which the neuronal circuits that involve these brain regions contribute to WM is still unclear. Here, in a large sample of healthy young adults, we first identified the core WM regions by linking WM accuracy to resting-state functional connectivity with the bilateral dorsolateral prefrontal cortex (dLPFC; a principal region in the central-executive network, CEN). Then a spectral dynamic causal modeling (spDCM) analysis was performed to quantify the effective connectivity between these regions. Finally, the effective connectivity was correlated with WM accuracy to characterize the relationship between these connections and WM performance. We found that the functional connections between the bilateral dLPFC and the dorsal anterior cingulate cortex (dACC) and between the right dLPFC and the left orbital fronto-insular cortex (FIC) were correlated with WM accuracy. Furthermore, the effective connectivity from the dACC to the bilateral dLPFC and from the right dLPFC to the left FIC could predict individual differences in WM. Because the dACC and FIC are core regions of the salience network (SN), we inferred that the inter- and causal-connectivity between core regions within the CEN and SN is functionally relevant for WM performance. In summary, the current study identified the dLPFC-related resting-state effective connectivity underlying WM and suggests that individual differences in cognitive ability could be characterized by resting-state effective connectivity.

Disrupted effective connectivity of the sensorimotor network in amyotrophic lateral sclerosis.

Although dysfunctional sensorimotor network (SMN) has been frequently involved in the pathogenesis of amyotrophic lateral sclerosis (ALS), the causal relationship within this network remains unexplored. In this study, spectral dynamic causal modeling was applied to resting-state functional magnetic resonance imaging data to estimate the causal relationship of SMN in a cohort of 20 ALS patients and 21 healthy controls. The SMN components were first extracted using an independent component analysis, and then compared between the two groups to identify the abnormalities in SMN. In ALS patients, we found significant regional activity alterations in the left primary motor cortex (M1), the left primary somatosensory cortex (S1), and the right supplementary motor cortex (SMA). Among these regions, spectral DCM revealed missing closed-loop circuit between the left M1 and the right SMA, and lost projection from the right SMA to the left S1 in ALS. These findings may reflect the influences of the loss of motor neurons on motor function in ALS, and provide compelling evidence for a breakdown of the sensorimotor neural circuits in ALS. In conclusion, this study elucidates a neurobiological model that may explain the functional impairments of the SMN in ALS, and provides much deeper insights into the pathophysiology of this disease.

The mitochondrial DNA 10197 G > A mutation causes MELAS/Leigh overlap syndrome presenting with acute auditory agnosia.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes/Leigh (MELAS/LS) overlap syndrome is a mitochondrial disorder subtype with clinical and magnetic resonance imaging (MRI) features that are characteristic of both MELAS and Leigh syndrome (LS). Here, we report an MELAS/LS case presenting with cortical deafness and seizures. Cranial MRI revealed multiple lesions involving bilateral temporal lobes, the basal ganglia and the brainstem, which conformed to neuroimaging features of both MELAS and LS. Whole mitochondrial DNA (mtDNA) sequencing and PCR-RFLP revealed a de novo heteroplasmic m.10197 G > A mutation in the NADH dehydrogenase subunit 3 gene (ND3), which was predicted to cause an alanine to threonine substitution at amino acid 47. Although the mtDNA m.10197 G > A mutation has been reported in association with LS, Leber hereditary optic neuropathy and dystonia, it has never been linked with MELAS/LS overlap syndrome. Our patient therefore expands the phenotypic spectrum of the mtDNA m.10197 G > A mutation.

Advanced hyperspectral video imaging system using Amici prism.

In this paper, we propose an advanced hyperspectral video imaging system (AHVIS), which consists of an objective lens, an occlusion mask, a relay lens, an Amici prism and two cameras. An RGB camera is used for spatial reading and a gray scale camera is used for measuring the scene with spectral information. The objective lens collects more light energy from the observed scene and images the scene on an occlusion mask, which subsamples the image of the observed scene. Then, the subsampled image is sent to the gray scale camera through the relay lens and the Amici prism. The Amici prism that is used to realize spectral dispersion along the optical path reduces optical distortions and offers direct view of the scene. The main advantages of the proposed system are improved light throughput and less optical distortion. Furthermore, the presented configuration is more compact, robust and practicable.

Experimental observation of lateral emission in freestanding GaN-based membrane devices.

This Letter describes a double-sided process to fabricate freestanding membrane devices on a GaN-on-silicon platform. The photoluminescence measurement is taken to characterize the optical performance. A large portion of the excited light from InGaN/GaN multiple quantum wells is trapped as waveguide modes and propagates in different directions. Experimental results show that the propagation direction of the waveguide mode can be converted into the direction normal to the surface at the edge of a freestanding membrane, and the emitted light is attenuated due to light propagation loss before it gets out from the edge. Subwavelength grating can also convert waveguide modes into air modes on a freestanding membrane. These results suggest that the emission efficiency can be greatly improved by employing more efficient light extraction methods and that GaN-based photonic waveguides are promising in the visible range.