Tuning the diffusion constant to optimize the readout of positional information of spatial concentration patterns

Positional information encoded in spatial concentration patterns is crucial for the development of multicellular organisms.However,it is still unclear how such information is affected by the physically dissipative diffusion process.Here we study one-dimensional patterning systems with analytical derivation and numerical simulations.We find that the diffusion constant of the patterning molecules exhibits a nonmonotonic effect on the readout of the positional information from the concentration patterns.Specifically,there exists an optimal diffusion constant that maximizes the positional information.Moreover,we find that the energy dissipation due to the physical diffusion imposes a fundamental upper limit on the positional information.

Characteristics and utility of combined duplex color-coded ultrasonography in the cervical rotational position with head MRI and MRA in the differential diagnosis of apogeotropic direction-changing positional nystagmus

Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology in cases of apogeotropic direction-changing positional nystagmus(DCPN).Methods:Thirty patients with apogeotropic DCPN were classified into 11 cases of central disease,seven cases of mixed central and peripheral disease,and 12 cases of peripheral disease by differential diagnosis based on various balance function,neuro-otological,and imaging tests.Cervical ultrasonography using the cervical rotation method and MRI and MRA of the head and neck were performed in most patients with apogeotropic DCPN.We reviewed the presence of abnormal imaging findings according to the disease etiology.Results:Of the 30 patients with apogeotropic DCPN,23 showed vascular abnormalities or central lesions on imaging.Vascular lesions were found in six of the 12 patients with peripheral disease.Cervical ultrasonography with cervical rotation detected blood flow disturbance in the vertebral artery in eight patients in whom the disturbance could not be detected by MRI or MRA of the head and neck.Discussion:We hypothesize that the causative disease of apogeotropic DCPN may be strongly associated with circulatory insufficiency of the vertebrobasilar and carotid arteries,and that impaired blood flow in these vessels may affect peripheral vestibular and central function.In patients with apogeotropic DCPN,examinations of vestibular function,central nervous system symptoms,and brain hemodynamics are valuable for differential diagnosis.

Treatment of benign paroxysmal positional vertigo. A clinical review

Benign paroxysmal positional vertigo(BPPV) is the most frequent episodic vestibular disorder. It is due to otolith rests that are free into the canals or attached to the cupulas. Well over 90% of patients can be successfully treated with manoeuvres that move the particles back to the utriculus. Among the great variety of procedures that have been described, the manoeuvres that are supported by evidenced-based studies or extensive series are commented in this review. Some topics regarding BPPV treatment, such as controlling the accuracy of the procedures or the utility of post-manoeuvre restrictions are also discussed.

Probable benign paroxysmal positional vertigo, spontaneously resolved:Incidence in medical practice, patients’ characteristics and the natural course

Background: Probable benign paroxysmal positional vertigo, spontaneously resolved (pBPPVsr), is a variant of benign paroxysmal positional vertigo (BPPV) in which there is no observable nystagmus and no vertigo with any positional maneuver. Objectives: To calculate the incidence pBPPVsr, compare the characteristics of the patients with pBPPVsr and BPPV not spontaneously resolved and describe the spontaneous resolution in the natural course of BPPV. Methods: Multicenter prospective descriptive study. During a one-year period, all patients with suspected BPPV that presented to the Neurotology Units of five participating centers were recruited. The incidence of pBPPVsr was calculated as a percentage of the total number of patients with BPPV. The prevalence of several variables was compared between pBPPVsr and BPPV not spontaneously resolved. The timing of spontaneous resolution was estimated using Kaplan-Meier curves. Results: 457 patients met the inclusion criteria. The incidence of pBPPVsr was 33.5%. It was significantly higher in males, in patients with normal bone mass and in patients who were not taking sulpiride. A rate of 18% of spontaneous resolution after the first month and 51% after the first year was found. This percentage did not change in a significant way after this moment. The curves for males, patients under 50 and patients with normal blood pressure decreased significantly faster. Conclusions: In our serie, BPPV spontaneously resolved in half of the patients with BPPV during the first year. This seemed to occur more commonly in males and could have been hindered by sulpiride intake, osteoporosis, advanced age and high blood pressure.

Climatic variations and benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo(BPPV) is probably the most common diagnosis at vertigo clinics.Seasonal cycles of several human illnesses could be attributed variously to changes in atmospheric or weather conditions.In this retrospective study,patients with BPPV from January 2010 to December 2012 were studied,and their charts were reviewed.Statistical analysis revealed a statistically significant difference in patients’ numbers among different months of the year.Also there is a significant statistical correlation between the numbers of patients with climatic variations especially the temperature.The present paper discusses the possible explanations for these results which confirms the seasonal variations in BPPV,together with a review of literature to view the possible associations with other disorders that causes such seasonality.

Differentiation of Positional Isomers of Propyl Alcohols Using Filament-Induced Fluorescence

We experimentally demonstrate the recognition of positional isomers of propyl alcohol vapor through nonlinear fluorescence induced by high-intensity femtosecond laser filaments in air. By measuring characteristic fluorescence of n-propyl and isopropyl alcohol vapors produced by femtosecond filament excitation, it is found that they show identical spectra, that is, those from molecular bands of CH, C2, Nit, OH and CN, while the relative intensities are different. By comparing the ratios of the CH and C2 signals, the two propyl alcohol isomers are differentiated. The different signal intensities are ascribed to different ionization potentials of the two isomer molecules, leading to different production efficiencies of fluorescing fragments.

BENIGN PAROXYSMAL POSITIONAL VERTIGO

One of the most common causes of vertigo is Benign Paroxysmal Positional Vertigo(BPPV),a sensation of spinning that is caused by a sudden change in head position.This type of vertigo was first described by Robert Barany in the early 1920s[1].He suggested that BPPV was caused by abnormal otoliths,also called statoconium or otoconius,a structure in the saccule or utricle in

Causes and treatment of idiopathic benign paroxysmal positional vertigo based on endocrinological and other metabolic factors

The genesis of the Benign Paroxysmal Positional Vertigo(BPPV)seems to be related to some metabolic factors.These factors,such as vitamin D,glucocorticoids,and even thyroid and growth hormones,can affect bone metabolism and the mineralization of otoconia.It also seems to link to factors related to aging or nutritional habits.Besides,since the incidence of BPPV is quantitatively higher in women than in men,female sex steroids could be associated with this process.It could be useful to understand how these factors act in otoconial mineralization if we want to develop treatments aimed at preventing or delaying BPPV recurrences.In this review,we will analyze the role of these metabolic and hormonal factors in otoconial mineralization and in the treatment of BPPV.

A Numerical Investigation of the Effects of Benign Paroxysmal Positional Vertigo on the Balance Function of the Inner Ear

A three-dimensional numerical model of the membranous labyrinth of the semicircular canal of the inner ear was established to investigate the effects of canalithiasis of BPPV on the balance function of the inner ear.The movement of otolith particles in the membranous labyrinth was simulated when a person turns his head to a specific position.The effects of otolith movements on the balance function of the inner ear were simulated for different numbers,diameters,and initial positions of otoliths.The simulation results show that the otolith diameter affects the movement duration of otoliths in the membranous labyrinth.The number and diameter of otoliths,the diameter of the membranous labyrinth,and the initial position of the otoliths can cause changes in the pressure difference on both sides of the cupula of the crista ampullaris(cupula).The latent period and onset period are related to the diameter of otolith particles and the position of the head.There is also a correlation between the severity of the disease and the diameter and number of otolith particles.

A method for improving graph queries processing using positional inverted index (P.I.I) idea in search engines and parallelization techniques

The idea of positional inverted index is exploited for indexing of graph database. The main idea is the use of hashing tables in order to prune a considerable portion of graph database that cannot contain the answer set. These tables are implemented using column-based techniques and are used to store graphs of database, frequent sub-graphs and the neighborhood of nodes. In order to exact checking of remaining graphs, the vertex invariant is used for isomorphism test which can be parallel implemented. The results of evaluation indicate that proposed method outperforms existing methods.

A comparative study of two methods for treatment of benign paroxysmal positional vertigo in the emergency department

Introduction: Posterior canal benign paroxysmal positional vertigo (PC-BPPV) is considered the mostcommon cause of peripheral vertigo in the emergency department (ED). Although the canalith repositioning maneuver (CRM) is the standard of care, the most effective method to deliver it in the ED hasbeen poorly studied.Objective: To compare two protocols of the Epley maneuver for the treatment of PC-BPPV.Patients and methods: We prospectively recruited 101 patients with unilateral PC-BPPV on physical examination, randomizing them to either a single Epley maneuver (EM) (n ¼ 46) or multiple maneuvers(n ¼ 55) on the same visit. Measured outcomes included presence/absence of positional nystagmus,resolution of vertigo, and score on the dizziness handicap inventory (DHI) at follow-up evaluations. TheDHI was stratified into mild ( 30) and moderate-severe (>30).Results: Normalization of the Dix-Hallpike maneuver at day 5 was observed in 38% of the single EMgroup and 44.4% in the multiple EM group (p ¼ 0.62). The DHI showed reduction from 42.2 (SD 18.4) to31.9 (SD 23.7) in the single EM group and from 43.7 (SD 22.9) to 33.5 (SD 21.5) in the multiple EM group(p ¼ 0.06). A higher number of patients improved from moderate-severe to mild DHI (p ¼ 0.03) in thesingle EM group compared to the multi-EM group (p ¼ 0.23).Conclusion: There was no statistically significant difference between performing a single EM versusmultiple EMs for treatment of PC-BPPV in the emergency department. The single EM approach isassociated with shorter physical contact between patients and examiner, which is logically safer in apandemic context.

Role of subjective visual vertical in patients with posterior canal benign paroxysmal positional vertigo as a prognostic marker after canalith repositioning maneuver

Objective:To study the potential role of subjective visual vertical(SVV)as a prognostic marker for canalith repositioning maneuver(CRM)in patients with posterior canal benign paroxysmal positional vertigo(PC-BPPV)for the Indian population.Methods:SVV was examined in 30 patients with PC-BPPV before and after canalith repositioning maneuver and after complete resolution of PC-BPPV.Study parameters included the mean of 10 angular tilt readings and direction of deviation,which were compared before and after CRM and following complete resolution of PC-BPPV.Results:The angle of SVV tilt was greater and deviated towards the affected ear before CRM in all patients,which decreased significantly shortly after CRM and continued to decrease after complete resolution of PC-BPPV(p<0.0001).Conclusions:SVV can be used to test utricular dysfunction in PC-BPPV.The angle of tilt improves in response to CRM,which may be used as a prognostic marker in patients with PC-BPPV receiving CRM.

A possible objective test to detect benign paroxysmal positional vertigo. The role of the caloric and video-head impulse tests in the diagnosis

Background:Benign paroxysmal positional vertigo(BPPV)is characterized by vertigo lasting from seconds to minutes,induced by head movements.Objectives:Our study aimed to investigate the clinical significance of the caloric vestibular and video head-impulse tests(vHIT)diagnosing the disorder.Methods:68 patients suffering from posterior canal BPPV(25 male,43 females,mean age±SD,54.5±13.2 years)and 56 patients with a normal functioning vestibular system as control were investigated.Bithermal caloric test and vHIT was performed during the same medical check-up.Canal paresis(CP%),gain(GA)and asymmetry(GA%)parameters were calculated.Results:The Dix-Hallpike manoeuvre was only positive in 4%of this population.The CP%parameter was only pathologic in two patients,and there was no significant difference between control and BPPV patients(p=0.76).The GA value was never under 0.8 in this population,but GA%was abnormal in 63.2%.A significant difference comparing the GA%values to the control group was seen(p=0.034).There was no correlation detected between the CP%and GA%values in BPPV.Regarding the GA%value,61%sensitivity and 76%specificity was seen.Conclusion:The Dix-Hallpike manoeuvre was not often positive in the non-acute phase of BPPV;therefore,objective testing is essential.The caloric test does not have clinical significance in BPPV,but vHIT can be helpful based on the GA%parameter。

A New Approach to Assess the Positional Accuracy of Maps Generated by GIS Overlay Operations

This paper proposes a new approach to assess the positional accuracy of maps generated by overlaying multi_scale spatial data layers with different levels of positional accuracy.The existing techniques for assessing the positional accuracy of point,line and polygon features is first examined.Then a taxonomy of graphic features on the derived maps is developed by analyzing the specific processes of overlay operations.Finally,a detailed description of the new approach is provided and the implementation of this new method in practical applications is described.

Residual Network with Enhanced Positional Attention and Global Prior for Clothing Parsing

Clothing parsing, also known as clothing image segmentation, is the problem of assigning a clothing category label to each pixel in clothing images. To address the lack of positional and global prior in existing clothing parsing algorithms, this paper proposes an enhanced positional attention module(EPAM) to collect positional information in the vertical direction of each pixel, and an efficient global prior module(GPM) to aggregate contextual information from different sub-regions. The EPAM and GPM based residual network(EG-ResNet) could effectively exploit the intrinsic features of clothing images while capturing information between different scales and sub-regions. Experimental results show that the proposed EG-ResNet achieves promising performance in clothing parsing of the colorful fashion parsing dataset(CFPD)(51.12% of mean Intersection over Union(mIoU) and 92.79% of pixel-wise accuracy(PA)) compared with other state-of-the-art methods.

Acute thrombosis of the carotid artery associated with positional nystagmus at multiple planes

Objective:An acute onset central pathology without any clear neurological symptoms may mimic peripheral vestibular problem in an emergency setting.A 54-year-old man suddenly developed dizziness without any cranial nerve symptoms,paresis,cerebellar signs or sensory disturbances except upbeat positional nystagmus at multiple provoked positions which alerted for a possible acute central pathology.Findings:An instantaneous magnetic resonance imaging and angiography studies further showed obstruction of the left internal carotid artery above the bifurcation.The patient’s subsequent prognosis was consistent with good recovery following anti-coagulant therapy.A follow-up MRI and angiography showed resolution of thrombosis.Conclusion:It should be kept in mind that positional nystagmus is likely to occur in central pathologies.Differentiation between benign paroxysmal positional vertigo and central positioning nystagmus is critical.

Partition of Forecast Error into Positional and Structural Components

Weather manifests in spatiotemporally coherent structures.Weather forecasts hence are affected by both positional and structural or amplitude errors.This has been long recognized by practicing forecasters(cf.,e.g.,Tropical Cyclone track and intensity errors).Despite the emergence in recent decades of various objective methods for the diagnosis of positional forecast errors,most routine verification or statistical post-processing methods implicitly assume that forecasts have no positional error.The Forecast Error Decomposition(FED)method proposed in this study uses the Field Alignment technique which aligns a gridded forecast with its verifying analysis field.The total error is then partitioned into three orthogonal components:(a)large scale positional,(b)large scale structural,and(c)small scale error variance.The use of FED is demonstrated over a month-long MSLP data set.As expected,positional errors are often characterized by dipole patterns related to the displacement of features,while structural errors appear with single extrema,indicative of magnitude problems.The most important result of this study is that over the test period,more than 50%of the total mean sea level pressure forecast error variance is associated with large scale positional error.The importance of positional error in forecasts of other variables and over different time periods remain to be explored.

A New Approach to Simulate Positional Error of Line Segment in GIS

To determine the distribution of positional error of a line segment, Monte Carlo approach is applied to simulate the probability density function of a line segment with the assumption that the error of endpoints in a line segment follows a two-dimensional normal distribution. For such purpose, a stochastic generator used for uncertain endpoints with the two-dimensional normal distribution is presented. This forms the basis of the generation of random line segment for the simulation of the error model of a whole line segment. The error models cover the cases where two endpoints are either independent or dependent to each other, also including a special case that the distance between two random endpoints in a line segment is close enough.

Direction-fixed positional nystagmus following head-roll testing:how is it related with a vestibular pathology?

Objective:The goal of this study is to analyze the clinical view of patients with direction-fixed positional nystagmus(DFPN)following head-roll maneuver.Methods:Sixty patients with DFPN were reviewed retrospectively.Patients were categorized into 3 groups according to the direction of nystagmus based on rotation side.Associated problems were documented,and cumulative data were compared between groups.One-way analysis of variance(ANOVA test)was used for statistical analysis(P<0.05).Results:Thirty-three patients(55%)had stronger nystagmus beating towards the direction of head-roll(Group-A).Three patients developed geotropic LC-BPPV.Fourteen patients had inner ear disease.Sixteen patients(27%)had stronger nystagmus beating against the direction of head roll(Group-B).Nine patients had inner ear disease.None of the patients tested with head-shaking had change of direction of nystagmus.Eleven patients(18%)had DFPN with equal velocity during right or left head-roll maneuver(Group-C).Of those,nine patients had inner ear disease.None of the patients had change of direction of nystagmus.Comparison of the incidence of associated problems(migraine,vestibular neuronitis,Meniere’s disease etc.)in each group was not statistically significant(P˃0.05).Conclusion:Patients with DFPN should be followed for a possibility of vestibular pathology since vestibular problem was documented for more than half of the patients in the follow-up.On the other hand,DFPN could be related with a temporary reason(thermal,physical or drug effect etc.)in some patients who do not exhibit any associated disease.Head-shaking testing is recommended to expose the lateral canal BPPV.But the incidence is low.

Benign paroxysmal positional vertigo with congenital nystagmus: A case report

BACKGROUND Benign paroxysmal positional vertigo(BPPV)is a form of temporary vertigo induced by moving the head to a specific position.It is a self-limited,peripheral,vestibular disease and can be divided into primary and secondary forms.Congenital nystagmus(CN),an involuntary,rhythmic,binocular-symmetry,conjugated eye movement,is found at birth or within 3 mo of birth.According to the pathogenesis,CN can be divided into sensory-defect nystagmus and motordefect nystagmus.The coexistence of BPPV and CN is rarely seen in the clinic.CASE SUMMARY A 62-year-old woman presented to our clinic complaining of a 15-d history of recurrent positional vertigo.The vertigo lasting less than 1 min occurred when she turned over,sometimes accompanied by nausea and vomiting.Both the patient and her father had CN.Her spontaneous nystagmus was horizontal to right;however,the gaze test revealed variable horizontal nystagmus with the same degree when the eyes moved.The patient’s Dix-Hallpike test was normal,except for persistent nystagmus,and the roll test showed severe variable horizontal nystagmus,which lasted for about 20 s in the same direction as her head movement to the right and left,although the right-side nystagmus was stronger than the left-side.Since these symptoms were accompanied by nausea,she was diagnosed with BPPV with CN and treated by manual reduction.CONCLUSION Though rare,if BPPV with CN is correctly identified and diagnosed,reduction treatment is comparably effective to other vertigo types.