Kurtosis Parameters Research Articles

Coupling characteristics and kurtosis parameter of partially coherent beams in turbulent atmosphere

ABSTRACTCoupling properties and kurtosis parameter (K parameter) of arbitrary beams propagating through atmospheric turbulence are investigated. A correlation factor (C4-factor) is introduced to describe the influence of turbulence on coupling characteristics. The general analytical expression for C4-factor of arbitrary beams in atmospheric turbulence is derived. It is shown that C4-factor of arbitrary beams in the turbulent atmosphere depends on the initial second-order moments and fourth-order moments and turbulence quantities. Taking the partially coherent anomalous elliptical hollow Gaussian (PCAEHG) beam as an example, we can obtain that C4-factor decreases as structure constant of the refractive index fluctuations and inner scale increase, and waist width and transverse coherence length decrease when z > 5 km. Moreover, K parameter of PCAEHG beam in turbulent atmosphere converges to 2 when propagation distance is large enough. It indicates that the profile of PCAEHG beams in turbulent atmosphere finally evolves into fundamental Gaussian distribution.

Propagation properties of optical bottle beam in turbulence

We study the propagation properties of optical bottle beams in turbulent atmosphere. By allowing the mathematical expression of source plane to cover both the symmetric and asymmetric forms, the beam is propagated through turbulence using random phase screens. On the source plane, the intensity profile of the bottle beam resembles a dark hollow beam with an outside ring for symmetric cases, whereas it becomes divided into two or more separate lobes for the asymmetric cases. During propagation, both symmetric and asymmetric beams concentrate the intensity toward the center, eventually assuming a Gaussian shape, where this process seems to be more rapid for the former beam types. The rising trend of the kurtosis parameter of bottle beams changes to a falling trend when the refractive index structure constant is reduced from 10 − 14 to 10 − 13 m − 2/3.

Beam spreading, kurtosis parameter and Strehl ratio of partially coherent cosh-Airy beams in atmospheric turbulence

In order to reduce turbulence-induced degeneration or resist the turbulence effect in non-diffraction partially coherent Airy optical fields, we introduce the cosh function to partially coherent Airy beam in turbulence, and focus our attention on the dependence of beam spreading, kurtosis parameter and Strehl ratio on cosh modulation parameter in the condition of the fixed input power. The results show that the resulting beam possesses more side lobes, and it can make main lobe to acquire more peak intensity in atmospheric propagation. Beam spreading of non-zero cosh modulation parameter is less sensitive to turbulence than that for zero value of cosh modulation parameter. The kurtosis parameter or Strehl ratio of partially coherent cosh-Airy beams can be further improved by increasing cosh modulation parameter. It means that partially coherent cosh-Airy beams with a larger cosh modulation parameter bring advantages in beam spreading, sharpness and peak intensity when compared with partially coherent Airy beams, which could have potential application in optical radar detection and free-space laser communication.

Diffusion kurtosis imaging histogram parameter metrics predicting survival in integrated molecular subtypes of diffuse glioma: An observational cohort study

PurposeThe aim of the study was to assess the predictive value of preoperatively assessed diffusion kurtosis imaging (DKI) metrics as prognostic factors in the 2016 World Health Organization Classification of Tumors of the Central Nervous System integrated glioma groups. Material and methodsSeventy-seven patients with histopathologically confirmed treatment-naïve glioma were retrospectively assessed between 08/2013 and 10/2017 using mean kurtosis (MK) and mean diffusivity (MD) histogram parameters from DKI, overall and progression-free survival, and relevant prognostic molecular data (isocitrate dehydrogenase, [IDH]; alpha-thalassemia/mental retardation syndrome X-linked, [ATRX]; chromosome 1p/19q loss of heterozygosity). Receiver operating characteristic (ROC) analysis was performed on metric variables to determine the optimal cutoff-values. The Kaplan-Meier method was used to assess univariate survival data. A multivariate Cox proportional hazards model was performed on significant results from the univariate analysis. ResultsThere were significant differences in overall and progression-free survival between patient age (p = 0.001), resection statuses (p = 0.002), WHO glioma grades (p < 0.0001), and integrated molecular profiles (p < 0.0001). Survival was significantly better in patients with lower MK and higher MD values globally (p = 0.009), in gliomas without chromosome 1p/19q LOH (p < 0.0001), and those with retained ATRX expression (p = 0.008). ConclusionsPatient age and MK from DKI from DKI are relevant factors for preoperatively predicting overall and progression-free survival. Regarding the molecular subgroups, they seem to be predictive in gliomas with ATRX retention, representing a feature of IDH wild-type gliomas.

Circular Lorentz-Gauss beams.

A circular Lorentz-Gauss beam is introduced. The analytical optical field of the circular Lorentz-Gauss beam passing through a paraxial ABCD optical system is derived. Based on the second- and higher-order moments of the light intensity, the analytical beam propagation factor of a circular Lorentz-Gauss beam and the analytical kurtosis parameter of a circular Lorentz-Gauss beam passing through a paraxial ABCD optical system have also been derived. The properties of the circular Lorentz-Gauss beam propagating in free space are demonstrated. The normalized intensity distribution, the beam half width, the beam waist, the divergence, the beam propagation factor, and the kurtosis parameter of the circular Lorentz-Gauss beam are compared with those of the corresponding Lorentz-Gauss beam, respectively. The main difference between the circular Lorentz-Gauss and the Lorentz-Gauss beams is their different peripheries. The circular Lorentz-Gauss beam has better symmetry than the Lorentz-Gauss beam. The beam propagation factor of the circular Lorentz-Gauss beam is always slightly larger than that of the Lorentz-Gauss beam. Therefore, the circular Lorentz-Gauss beam is the enrichment and supplement of the existing Lorentz-Gauss beam.

Dynamic changes in hippocampal diffusion and kurtosis metrics following experimental mTBI correlate with glial reactivity.

Diffusion magnetic resonance imaging biomarkers can provide quantifiable information of the brain tissue after a mild traumatic brain injury (mTBI). However, the commonly applied diffusion tensor imaging (DTI) model is not very specific to changes in the underlying cellular structures. To overcome these limitations, other diffusion models have recently emerged to provide a more complete view on the damage profile following TBI. In this study, we investigated longitudinal changes in advanced diffusion metrics following experimental mTBI, utilising three different diffusion models in a rat model of mTBI, including DTI, diffusion kurtosis imaging and a white matter model. Moreover, we investigated the association between the diffusion metrics with histological markers, including glial fibrillary acidic protein (GFAP), neurofilaments and synaptophysin in order to investigate specificity. Our results revealed significant decreases in mean diffusivity in the hippocampus and radial diffusivity and radial extra axonal diffusivity (RadEAD) in the cingulum one week post injury. Furthermore, correlation analysis showed that increased values of fractional anisotropy one day post injury in the hippocampus was highly correlated with GFAP reactivity three months post injury. Additionally, we observed a positive correlation between GFAP on one hand and the kurtosis parameters in the hippocampus on the other hand three months post injury. This result indicated that prolonged glial activation three months post injury is related to higher kurtosis values at later time points. In conclusion, our findings point out to the possible role of kurtosis metrics as well as metrics from the white matter model as prognostic biomarker to monitor prolonged glial reactivity and inflammatory responses after a mTBI not only at early timepoints but also several months after injury.

Effects of surface texture parameters of cutting tools on friction conditions at tool-chip interface during dry machining of AISI 1045 steel

Abstract Dry machining is one of the essential steps towards achieving sustainable manufacturing processes. Sustainable dry machining can be further enhanced by using surface textured cutting tools where the micro-capillary networks on cutting tool surfaces are exploited for tribological benefit in the absence of cutting fluids. This paper presents the results of an experimental study in which rake surfaces of uncoated carbide cutting tools are textured at different levels, and orthogonal machining is performed on AISI 1045 steel under dry machining condition. The results show that skewness, kurtosis, and other surface texture parameters on the rake surface significantly influence the machining forces via altering friction conditions at the tool-chip interface. Further, the orientation of the cutting tool’s surface texture pattern has a strong effect on the capability of the surface micro-capillary network to allow atmospheric air, which must serve as a lubricant in dry cutting, to access portions of the tool-chip contact zone.

Diffusional Kurtosis along the Corticospinal Tract in Adult Normal Pressure Hydrocephalus.

Normal Pressure Hydrocephalus is a reversible form of dementia characterized by enlarged ventricles, which can deform and cause disruptions to adjacent white matter fibers. The purpose of this work was to examine how diffusion and kurtosis parameters vary along the corticospinal tract and determine where along this path microstructure is compromised in patients diagnosed with normal pressure hydrocephalus. We hypothesized that disruption of the corticospinal tract from ventricular enlargement can be measured using diffusion MR imaging and this will be quantified in periventricular regions. We developed a method to analyze diffusion parameters at discrete points along neural tracts. We then used diffusion MR imaging data from patients with Alzheimer disease and healthy controls to compare whether diffusion along the corticospinal tract differs from that of patients with normal pressure hydrocephalus. We found that diffusion parameters can differentiate patients with normal pressure hydrocephalus from those with Alzheimer disease and healthy controls: Axial diffusion, axial kurtosis, and the axonal water fraction were found to differ significantly across groups (P < .05) in an area located close to the superior internal capsule and corona radiata but below the cortex. A lower axonal water fraction indicates a lower axonal density in the corticospinal tract, which may indicate permanent damage. Lower axial kurtosis may imply that axons are being more aligned due to compression.

Vokal Kist Probleminin Yüksek Dereceli Momentler ve Destek Vektör Makineleri Kullanılarak Tespiti

The voice disorders occurring due to the problems in the voice producing organs cause some changes in the intensity or tone of the voice. It is difficult to identify the diseased voice by the reason of its variable and different nature. One of the most popular voice disorder reasons is cyst which is located on the vocal cords. The aim of this study is to detect the vocal cyst problem by using acoustic voices data which were recorded from healthy people and patient with cyst diagnoses subjects by using high order statistics and support vector machines (SVMs) classifier. In this study, two experimental procedures were implemented for two different voice samples. In the first , /a/ vowel and the second, the Turkish word of “aydinlik” (mean in English “bright”) were investigated with skewness and kurtosis parameters which are third and fourth order cumulants (spectral moments), respectively. The obtained features values for healthy and cyst subjects were used as the SVMs’ inputs for classification . The experimental results show that the test accuracies of SVMs were found as 94.89% and 91.11% for /a/ vowel and “aydinlik” word, respectively. It is concluded from experimental studies that skewness provides more meaningful results than kurtosis in relation to distinguish into two voice groups as healthy and cyst . Additionally, it is assessed that the “aydinlik” is affective word for the pathological and normal acoustic voice discrimination as good as /a/vowel.

Geometric-Gamma Collective Modified Value-at-Risk Model in Life Insurance Risk

Claim risk is a payment made by the insurance company to the policyholder. Actuaries in insurance companies should be able to measure and control the risk of claims, in order to avoid losses to insurance companies. In this paper we analyze the Geometric-Gamma Collective Modified Value-at-Risk model in life insurance risk. In this research, there is a development of claim risk measure called Collective Modified Value-at-Risk, which is an extension of Collective Risk model. This Collective Modified Value-at-Risk model requires estimation of the mean, variance, skewness, and kurtosis parameters. The result of this research, is that the extent of this model can be applied to the risk of claims amount of non-normal distributed. Thus, the Collective Modified Value-at-Risk model can serve as one of the statistical alternatives for measuring the risk of claims on life insurance.

DIFFUSION-KURTOSIS IMAGING IN ASSESMENT OF BRAIN MICROSTRUCTURE. HEALTHY VOLUNTEERS MEASURMENTS

Aim:discover quantitative and qualitative variance of diffusion parameters in white and gray matter of healthyvolunteers brain. Discover correlation between diffusion and kurtosis parameters, find out if there is correlation between the parameters and aging microstructural changes.Materials and methods.14 healthy volunteers were investigated (9 men, 5 women; age from 21 to 55 years, mean 34). The volunteers were classified into two groups by age: 7 subjects who younger 35 (6 men and 1 woman, mean age 25) and 7 subjects who older 35 years (3 men and 4 women, mean age 44). We used 3.0 Tesla MRI (3.0T SignaHDxt, General Electric, USA) with 8 channel head coil, gradient strength 50 mT/m, slew rate 150 T/m/s. Diffusion imaging was based on echo planar “spin echo” sequence (SE EPI), TR = 10000 ms, TEmin = 102 ms, FOV = 240 mm, voxel size 3 × 3 × 3 mm3, 60 non-coplanar diffusion directions and three b-values: 0, 1000, 2500 s/mm2. Acquisition time of diffusion kurtosis imaging was 22 minutes. We excluded extracerebral areas on diffusion and kurtosis parametric maps using semi-automatic approach. After that, brain images were transformed to MNI152 space using affine method. Masks of 9 anatomical structures were applied to the transformed images. Diffusion and kurtosis values were measured in these structures.Results.Fractional anisotropy (FA) changed from 0.06 in lateral occipital cortex to 0.25 in cerebral white matter, kurtosis anisotropy (KA) changed from 0.03 to 0.14 in the same cerebral structures. Axial (AK), radial (RK) and mean kurtosis (MK) were minimal in superior frontal gyrus and maximal in cerebral white matter. AK changed from 0.55 to 0.72, RK changed from 0.62 to 1.05, MK from 0.59 to 0.88. Axial(AxEAD) and radial extra axonal water diffusion (RadEAD) were minimal in putamen and maximal in superior frontal gyrus. AxEAD was changing from 1.38 • 10–3 to 2.57 • 10–3, RadEAD from 1.03 • 10–3 to 2.34 • 10–3. Axonal water fraction (AWF) had minimal value 0,18 in superior frontal gyrus and maximal value 0.29 in cerebral white matter. Tortuosity (TORT) changed from 1.06 in lateral occipital cortex to 1.43 in cerebral white matter. There was significant difference between age groups in AWF, RK, RadEAD in putamen and in KA in superior temporal gyrus. Maximal correlation with age was in MK in superior temporal gyrus, anterior division. It was equal to 0.562.Conclusions:Diffusion kurtosis imaging is highly sensitive method of brain tissue microstructure assessment, which detects age-related changes.

Evaluation of patients with relapsing-remitting multiple sclerosis using tract-based spatial statistics analysis: diffusion kurtosis imaging

BackgroundDiffusion kurtosis imaging (DKI) has the potential to provide microstructural insights into myelin and axonal pathology with additional kurtosis parameters. To our knowledge, few studies are available in the current literature using DKI by tract-based spatial statistics (TBSS) analysis in patients with multiple sclerosis (MS). The aim of this study is to assess the performance of commonly used parameters derived from DKI and diffusion tensor imaging (DTI) in detecting microstructural changes and associated pathology in relapsing remitting MS (RRMS).MethodsThirty-six patients with RRMS and 49 age and sex matched healthy controls underwent DKI. The brain tissue integrity was assessed by fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr), mean kurtosis (MK), axial kurtosis (Ka) and radial kurtosis (Kr) of DKI and FA, MD, Da and Dr of DTI. Group differences in these parameters were compared using TBSS (P < 0.01, corrected). To compare the sensitivity of these parameters in detecting white matter (WM) damage, the percentage of the abnormal voxels based on TBSS analysis, relative to the whole skeleton voxels for each parameter was calculated.ResultsThe sensitivities in detecting WM abnormality in RRMS were MK (78.2%) > Kr (76.7%) > Ka (53.5%) and Dr (78.8%) > MD (76.7%) > FA (74.1%) > Da (28.3%) for DKI, and Dr (79.8%) > MD (79.5%) > FA (68.6%) > Da (40.1%) for DTI. DKI-derived diffusion parameters (FA, MD, and Dr) were sensitive for detecting abnormality in WM regions with coherent fiber arrangement; however, the kurtosis parameters (MK and Kr) were sensitive to discern abnormalities in WM regions with complex fiber arrangement.ConclusionsThe diffusion and kurtosis parameters could provide complementary information for revealing brain microstructural damage in RRMS. Dr and DKI_Kr may be regarded as useful surrogate markers for reflecting pathological changes in RRMS.

Propagation of hollow vortex Gaussian beams in a strongly nonlocal nonlinear media

An analytical expression of a hollow vortex Gaussian beam is derived in a strongly nonlocal nonlinear media. The analytical expressions of the beam width, the curvature radius, the kurtosis parameter, and the orbital angular momentum density for the hollow vortex Gaussian beam have been also derived. The normalized intensity, the beam width, the curvature radius, the kurtosis parameter, and the orbital angular momentum density versus the axial propagation distance are all periodic, and the period is the same. Their periodic behaviors are also demonstrated. When the parameter η is used to describe the strength of the nonlocality, the periodic behaviors of the normalized intensity distribution, the beam width, the curvature radius in the strongly nonlocal nonlinear media of η = 0.5 are opposite to those in the strongly nonlocal nonlinear media of η = 1.0, respectively. When η reaches a critical value, the normalized intensity distribution, the beam width, and the curvature radius keep unvaried upon propagation. The periodic evolution of the kurtosis parameter is independent of the parameter η. The magnitude of the orbital angular momentum density is inversely proportional to the beam width, while the corresponding distribution area is proportional to the beam width. The periodic evolutions of the hollow vortex Gaussian beam in the strongly nonlocal nonlinear media are well exhibited, and have promising application in optical switch and optical micromanipulation.

Diffusion kurtosis imaging as a neuroimaging biomarker in patients with carbon monoxide intoxication

Attempting suicide by burning charcoal can lead to carbon monoxide (CO) intoxication and cognitive deficits. Changes in white matter (WM) quantified by diffusion tensor imaging (DTI)-derived parameters have been validated to reflect cognitive test scores. As diffusion kurtosis imaging (DKI) measures biological microstructures using non-Gaussian diffusivity, we assessed the added-information of DKI with neuropsychological test scores as the major outcome measure.A total of 45 patients were enrolled and compared with 30 age-matched controls. The patients were stratified into acute or chronic phase according to the intervals of intoxication and assessments. WM status was assessed using tract-based spatial statistics for DKI and DTI topographies, and the sensitivity/specificity of either model was tested using area under the curve (AUC) analysis. To evaluate their clinical significance, values of DKI- and DTI-derived parameters were extracted from seven regions of interest (ROI) and correlated with neuropsychiatric scores.The kurtosis parameters were lower in the patients than in the controls but none of the parameters provided differentiations between the acute or chronic phase. Kurtosis fractional anisotropy (KFA) had a higher AUC than fractional anisotropy while the other 3 DTI parameters had higher AUC than the corresponding DKI ones. In clinical correlations, KFA value of right posterior WM correlated with visual memory (r = 0.326, p = 0.029), and KFA values of bilateral posterior WM correlated with the digit forward score (right: r = 0.302, p = 0.043; left: r = 0.314, p = 0.036).Although DTI was more sensitive in reflecting disease status, KFA may be more sensitive and specific than fractional anisotropy in cognitive test score predictions.

Inference about the Population Kurtosis with Confidence: Parametric and Bootstrap Approaches

This paper considers some classical and bootstrap methods in constructing confidence intervals for the kurtosis parameter of a distribution. The bootstrap techniques used are: Bias-Corrected Standard Bootstrap, Efron’s Percentile Bootstrap, Hall’s Percentile Bootstrap and Bias-Corrected Percentile Bootstrap. The performance of these estimators is compared through confidence intervals by determining the average width and probabilities of capturing the kurtosis parameter of a distribution. We observed that the parametric method works well in terms of coverage probability when data come from a normal distribution, while the bootstrap intervals struggled in constantly reaching a 95% confidence level. When sample data are from a distribution with negative kurtosis, both parametric and bootstrap confidence intervals performed well, although we noticed that bootstrap methods tend to have shorter intervals. When it comes to positive kurtosis, bootstrap methods perform slightly better than classical methods in the sense of high coverage probability. For illustration purposes, two real life health related data are analyzed.

Study on Feature Selection Methods for Depression Detection Using Three-Electrode EEG Data.

The early diagnosis of depression is important to the treatment of this condition, whereas a timely diagnosis can reduce the incidence of mortality caused in patients with depression. In the present study, we collected the EEG signals of Fp2, Fpz and Fp1, compared with 128 channels EEG, a simpler test (3 channels EEG) can make diagnosis more accessible and widespread, researchers can perform more tests on more patients given the same amount of time and money. The difference between the depressed and the non-depressed patients was explored by the linear and non-linear characteristics of these EEG signals. A total of 152 patients with depression and 113 healthy subjects participated in the study. In the current report, the linear features were as follows: peak, variance, inclination, kurtosis and Hjorth parameter. The nonlinear features included C0 complexity, correlation dimension, Shannon entropy, Kolmogorov entropy and power spectrum entropy. With regard to the aforementioned characteristics, the present report utilized four feature selection algorithms, namely WrapperSubsetEval, CorrelationAttributeEval, GainRatioAttributeEval, and PrincipalComponents and five classification algorithms that included Support Vector Machine, K-Nearest Neighbor, Decision Tree, Logistics Regression and Random Forest. The experimental results indicated that the WrapperSubsetEval of the wrapper class exhibited higher performance compared with the other three feature selection algorithms on each classifier, whereas the highest classification accuracy was 76.4. It is suggested that this analysis may be a complementary tool to aid psychiatrists in the diagnosis of depressed patients.

Quantitative diffusion MRI using reduced field-of-view and multi-shot acquisition techniques: Validation in phantoms and prostate imaging

PurposeTo evaluate the reproducibility of quantitative diffusion measurements obtained with reduced Field of View (rFOV) and Multi-shot EPI (msEPI) acquisitions, using single-shot EPI (ssEPI) as a reference. MethodsDiffusion phantom experiments, and prostate diffusion-weighted imaging in healthy volunteers and patients with known or suspected prostate cancer were performed across the three different sequences. Quantitative diffusion measurements of apparent diffusion coefficient, and diffusion kurtosis parameters (healthy volunteers), were obtained and compared across diffusion sequences (rFOV, msEPI, and ssEPI). Other possible confounding factors like b-value combinations and acquisition parameters were also investigated. ResultsBoth msEPI and rFOV have shown reproducible quantitative diffusion measurements relative to ssEPI; no significant difference in ADC was observed across pulse sequences in the standard diffusion phantom (p = 0.156), healthy volunteers (p ≥ 0.12) or patients (p ≥ 0.26). The ADC values within the non-cancerous central gland and peripheral zone of patients were 1.29 ± 0.17 × 10−3 mm2/s and 1.74 ± 0.23 × 10−3 mm2/s respectively. However, differences in quantitative diffusion parameters were observed across different number of averages for rFOV, and across b-value groups and diffusion models for all the three sequences. ConclusionBoth rFOV and msEPI have the potential to provide high image quality with reproducible quantitative diffusion measurements in prostate diffusion MRI.

Atomic force microscopy analysis of surface topography of pure thin aluminum films

Pure aluminium thin films were deposited on stainless and mild steel substrates through rf magnetron sputtering at rf powers of 150 and 200 W. Surface analysis of the films was undertaken using atomic force microscopy. The surface structure evolution, roughness and distribution were examined and discussed. Power spectral density, skewness and Kurtosis parameters were used to explain the nature and distribution of the surface structures on the thin aluminium films as reported from the line profile analyses. The result shows that the morphologies of the surface structures of Al thin films vary with power and substrate type. The coatings also exhibited higher roughness at the power of 200 W. A strong link exists between the atomic force microscopy (AFM) observations and scanning electron microscopy (SEM) analysis, which implies that AFM can be considerably used to study the microstructural evolution of thin films prepared by magnetron sputtering.

Structural, morphological and optical properties of pulsed laser deposited ZnSe/ZnSeO3 thin films

The effect of varying laser pulses on structural, morphological and optical behavior of Pulsed Laser Deposited (PLD) ZnSe/ZnSeO3 thin films has been investigated. The films were grown by employing Excimer laser (100 mJ, 248 nm, 18 ns, 30 Hz) at various number of laser pulses i.e. 3000, 4000, 5000 and 6000 with elevated substrate temperature of 300 °C. One film was grown at Room Temperature (RT) by employing 3000 number of laser pulses. In order to investigate the structural analysis of deposited films, XRD analysis was performed. It was observed that the room temperature is not favorable for the growth of crystalline film. However, elevated substrate temperature to 300°C, two phases with preferred orientation of ZnSeO3 (2 1 2) and ZnSe (3 3 1) were identified. AFM and SEM analysis were performed to explore the surface morphology of grown films. Morphological analysis also confirmed the non-uniform film growth at room temperature. At elevated substrate temperature (300 °C), the growth of dendritic rods and cubical crystalline structures are observed for lower number of laser pulses i.e. 3000 and 4000 respectively. With increased number of pulses i.e. 5000 and 6000, the films surface morphology becomes smooth which is confirmed by measurement of surface RMS roughness. Number of grains, skewness, kurtosis and other parameters have been evaluated by statistical analysis. In order to investigate the thickness, and optical properties of deposited films, ellipsometery and UV–Vis spectroscopy techniques were employed. The estimated band gap energy is 2.67 eV for the film grown at RT, whereas band gap values varies from 2.80 eV to 3.01 eV for the films grown at 300 °C with increasing number of laser pulses.

P08-Diffusion kurtosis imaging detects early microstructural changes in dorsal motor nucleus of vagus in intragastric rotenone mouse model of Parkinson’s disease

The aim was to determine whether diffusion kurtosis imaging (DKI-MRI) could detect changes in dorsal motor nucleus of vagus (DMV) in mice who received chronic administration of rotenone. This may help in early diagnosis of patients with Parkinson’s disease. Mice received vehicle (VEH) or rotenone (ROT) intragastrically for 4 months. DKI scanning was performed at 2, 3 and 4 months. ROI analysis was used to compare kurtosis and diffusivity parameters in GM regions. WM tracts were investigated using the tract-based spatial statistics. We found significant increase in mean kurtosis in DMV in the ROT group at 2 months. At 3 months we found increase in kurtosis and decrease in diffusivity in almost all regions of interest, showing once the pathology crosses the DMV it spreads throughout the brain. At 4 months all the changes vanished. ROT group showed significant motor impairment at 4 months. At 2 months the DKI parameters may improve the early diagnosis of PD by showing increase in mean kurtosis in the DMV. This may help in monitoring and developing neuroprotective therapy. On the other hand, the lack of the DKI signal changes between ROT and VEH groups at the 4 months probably reflects the brain atrophy.