Fluid pressurisation and earthquake propagation in the Hikurangi subduction zone.

In subduction zones, seismic slip at shallow crustal depths can lead to the generation of tsunamis. Large slip displacements during tsunamogenic earthquakes are attributed to the low coseismic shear strength of the fluid-saturated and non-lithified clay-rich fault rocks. However, because of experimental challenges in confining these materials, the physical processes responsible for the coseismic reduction in fault shear strength are poorly understood. Using a novel experimental setup, we measured pore fluid pressure during simulated seismic slip in clay-rich materials sampled from the deep oceanic drilling of the Papaku thrust (Hikurangi subduction zone, New Zealand). Here, we show that at seismic velocity, shear-induced dilatancy is followed by pressurisation of fluids. The thermal and mechanical pressurisation of fluids, enhanced by the low permeability of the fault, reduces the energy required to propagate earthquake rupture. We suggest that fluid-saturated clay-rich sediments, occurring at shallow depth in subduction zones, can promote earthquake rupture propagation and slip because of their low permeability and tendency to pressurise when sheared at seismic slip velocities.

Comparison of realistic head modeling methods in EEG source imaging - biomed 2010.

EEG inverse source imaging aims at reconstructing the underlying current distribution in the human brain using potential differences measured non-invasively from the head surface. A critical component of source reconstruction is the head volume conductor model used to reach an accurate solution of the associated forward problem, i.e., the simulation of the EEG for a known current source in the brain. The volume conductor model contains both the geometry and the electrical conduction properties of the head tissues and the accuracy of both parameters has direct impact on the accuracy of the source analysis. This was examined in detail with two different human head models. Two realistic head models derived from an averaged T1-weighted MRI dataset of the Montreal Neurological Institute (MNI) were used for this study. These models were: (1) BEM Model: a four-shell surface-based Boundary Elements (BEM) head model; (2) FDM Model: a volume-based Finite Difference (FDM) model, which allows better modeling accuracy than BEM as it better represents the cortical structures, such as, sulci and gyri in the brain in a three-dimensional head model. How model accuracy description influences the EEG source localizations was studied with the above realistic models of the head. We present here a detailed computer simulation study in which the performances of the two realistic four-shell head models are compared, the realistic MNI-based BEM Model and the FDM Model. As figures of merit for the comparative analysis, the point spread function (PSF) maps and the lead field (LF) correlation coefficients are used. The obtained results demonstrate that a better description of realistic geometry can provide a factor of improvement particularly important when considering sources placed in the temporal or in the occipital cortex. In these situations, using a more refined realistic head model will allow a better spatial discrimination of neural sources.

Threedimensional eeg source reconstruction on high performance computers methodological and computational issues.

This paper presents an original problem solving framework specifically conceived and designed to achieve high performance three-dimensional (3D) reconstruction of the sources of electroencephalographic (EEG) brain activity, named TEBAM (True Electrical Brain Activity Mapping). We describe the integrated framework that has been proposed and developed, specifying TEBAM's design characteristics, implementation and tools interconnections (pipelines). TEBAM relays on patient's specific realistic head modeling for the EEG forward and inverse problem evaluation and is implemented and optimized with a very flexible approach to solve in short time, by means of High Performance Computing resources, the large scale computations needed. Results of 3D True Electrical Brain Activity Mapping can be visualized in TEBAM framework in different multimodal ways, combining the anatomical information with the computed results to give an optimal insight of computation output, relying also on stereographic visualization.

Head modeling for realistic electrical brain activity mapping identification of a multimodal neuroimaging protocol.

Realistic electrical brain activity mapping implies reconstructing and visualizing sources of electrical brain activity within the specific patient's head. This requires the assumption of a precise and realistic volume conductor model of the specific subject's head, i.e., a 3-D representation of the head's electrical properties in terms of shape and electrical conductivities. Source reconstruction accuracy is influenced by errors committed in head modeling. Clinical images, MRI and CT, are used to identify the head structures to be included in the volume conductor head model. Modeling accuracy mainly relies on the correct image-based identification of head structures, characterized by different electrical conductivities, to be included as separate compartments in the model. This paper analyzes the imaging protocols used in clinical practice to define the most suitable procedures for identification of the various head structures necessary to build an accurate head model also in the presence of morphologic brain pathologies. Furthermore, tissues anisotropy is discussed and identified as well. With this work we have identified a protocol for the acquisition of multimodal patient's imaging data for realistic electrical brain activity mapping purposes, able to account for pathological conditions and for head tissues anisotropy.

Door-to-door prevalence survey of epilepsy in three Sicilian municipalities.

A door-to-door prevalence survey of epilepsy was conducted in 3 Sicilian municipalities, as of November 1, 1987. In phase 1, the screening by questionnaire of 24,496 eligible subjects (participation = 92%) identified 544 suspected to have epilepsy. In phase 2, neurological evaluation of the 544 subjects yielded 111 with epilepsy. Of the 111 subjects, 103 (93%) had been previously diagnosed, 68 (61%) were taking antiepileptic medication, and 81 (73%) had active epilepsy. Referring to the 81 subjects with active epilepsy, the seizure type was generalized in 60 (74%), partial in 19 (23%) and undetermined in 2 (3%). The prevalence of active epilepsy (per 1,000 population) was 3.3 overall, 3.5 for men and 3.2 for women. The age-specific patterns for active epilepsy differed by sex, with higher figures for men at younger ages (5-19 years) and older ages (50-99 years). The age-specific prevalence figures for active epilepsy were lower than those from previous Italian surveys.

Clinical facial photography in a small office: lighting equipment and technique.

The taking of clinical photographs, to record and to utilize during surgery, is an essential aspect of activity in every professional office or department of facial surgery. To obtain the best quality and consistency of results, many suggest the use of a professional lighting system composed of two or more flash units. An entire room, or a large part of it, should be permanently reserved for this use. In the last five years, I have developed and standardized a technique for taking facial photography, utilizing a single flash unit (monolight) in a small area that, after photographing, is cleared to allow space for other activities. A remarkable effort was dedicated to make the procedure easier, to save time, to reduce cost, and to make it possible to take a complete set of shots without the aid of an assistant.

Parkinson disease survival: a population-based study.

OBJECTIVE: To evaluate whether the survival of patients with Parkinson disease (PD) is shorter than that of the general population. DESIGN: Survival was investigated in a cohort of patients with PD previously identified during a population-based prevalence study (prevalence day, November 1, 1987, reference follow-up date, October 31, 1995). The survival of patients with PD was compared with that of a control sample randomly selected from the same population (2 controls for each case, matched for age, sex, and study municipality). The causes of death in the 2 groups were also compared. Both univariate and multivariate survival analyses were performed to investigate the association with disease-related variables. SETTING: A door-to-door 2-phase prevalence survey performed in 3 Sicilian municipalities. PATIENTS: Fifty-nine patients with PD and 118 controls. RESULTS: Patients with PD showed a high risk of death (relative risk, 2.3; 95% confidence interval, 1.60-3.39). Greater age at November 1, 1987, high Hoehn-Yahr score, and lack of levodopa therapy were associated with a lower survival on univariate analysis. Multivariate analysis confirmed the association between shorter survival among patients with PD and greater age on November 1, 1987. One-way analysis of variance indicated a different effect of levodopa therapy according to age. Multivariate analysis did not confirm this finding. Pneumonia was the cause of death most frequently associated with PD. CONCLUSION: This study indicates that patients with PD have a shorter survival time than the general population.

Stroke incidence and survival in three Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group.

We investigated the incidence of first-ever stroke in three Sicilian municipalities over the years 1984-1987. Case ascertainment involved two approaches: a door-to-door two-phase prevalence survey and a study of death certificates. Only first-ever strokes occurring within the study time interval were included, and diagnoses were based on specified criteria. We found 138 subjects who had experienced a first stroke over 73 488 person-years; the average incidence rate (new cases per 1000 population per year) was 1.9 overall, 1.7 in men, and 2.1 in women. Incidence increased steeply with age and was similar in men and women. Incidence was similar in the three study municipalities. The overall case-fatality rate was 35% at 30 days and 22% at one week. Survival after stroke was similar in men and women but better in younger compared to older stroke patients. Comparisons with previous studies suggest the absence of major geographic variations in stroke incidence within Italy.

[Acute gastroduodenal lesions and stress]. / Lesioni gastroduodenali acute e stress.

Haemorrhagic gastroduodenitis together with complicated peptic ulcer, are--after trauma--the most common causes of urgent admission in hospital for young people. In the present paper the Authors deal with the role of emotional disturbances, generated by environmental stress, in the pathogenesis of many gastrointestinal diseases in the young. They observed a rise in the incidence of gastroduodenal pathology (especially of the erosive-haemorrhagic form) in young males during military service. So they hypothesized that such high incidence of acute GDD during military service, could be attributed to abrupt changes in lifestyle, generating a significant environmental stress. The results of a clinical study on 65 young conscripts out of 483 who underwent EGDS for acute digestive symptoms also tested for psychological evaluation to stress response, are reported. In the 60.7% of all patients, MMPI (Minnesota Multiphasic Personality Inventory) test showed pathological alterations. Correlating the pathological findings with MMPI results, the Authors found that the 25% of patients suffering from oesophagitis, the 36.3% of those with peptic ulcers, the 68% of aspecific gastroduodenitis and the 75% of erosive-haemorrhagic gastroduodenitis, had psychological disturbances. The study shows that GDD in the young is a very frequent pathology, which may be triggered off by abrupt changes in life style, especially in those patients who are unable to react positively to changes in the outer world. GD pathology arises most frequently during the first five months of military service, especially within the third and the fourth month. The Authors conclude that a correct management of GDD in the young needs a versatile approach based on EGDS to establish the correct diagnosis, and on psychopathological investigations.

Incidence and lifetime prevalence of Bell's palsy in two Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group.

INTRODUCTION: In a door-to-door two-phase survey of common neurologic diseases conducted in two Sicilian municipalities, we investigated the incidence and the lifetime prevalence of Bell's palsy (BP). MATERIAL & METHODS: During phase I, we administered a screening instrument for facial palsy to 11,901 adult persons. During phase 2, study neurologists using specified diagnostic criteria evaluated those subjects who screened positive. RESULTS: We found 73 subjects who had experienced BP during their life. The lifetime prevalence as of November 1, 1987, was 642.8 cases per 100,000 population age 15 years and above. The prevalence increased with age and was similar in men and women. Eighteen episodes of BP occurred in the three years preceding the prevalence day. The average annual incidence rate was 52.8 new episodes per 100,000 population age 15 years and above. Incidence increased with age. CONCLUSION: Comparison with other incidence studies suggests some geographic variability.

Prevalence of lumbosacral radiculopathy in two Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group.

OBJECTIVES: As part of a door-to-door survey of neurologic diseases, we investigated the prevalence of lumbosacral radiculopathy (LR) in two Sicilian municipalities (N = 14,540, as of November 1, 1987). MATERIAL & METHODS: During phase 1, we administered a brief screening instrument to subjects in the study population. In phase 2, study neurologists using specified diagnostic criteria investigated those subjects who screened positive. Our case finding was restricted to subjects who manifested symptoms of LR in the six months preceding the prevalence day. RESULTS: We found 143 subjects affected by LR (112 definite, 31 possible) yielding a crude prevalence of 9.8 cases per 1,000 population. Age-specific prevalence was generally higher in men; it increased to a peak at age 50-59 years and decreased steadily thereafter. At the peak, prevalence was higher in factory workers, housewives, and clerks compared to workers in other occupations. CONCLUSIONS: LR is a common neurologic disease in the general population.

Prevalence of epilepsy. A door-to-door survey in the Sicilian community of Riposto.

In a door-to-door survey of common neurological disorders in Sicily (SNES Project), we administered a screening symptoms questionnaire and a brief neurological examination to detect epileptic patients. All of the subjects effectively resident in the community of Riposto on 1 November 1987 (prevalence day) were investigated (n = 9956). The subjects with a positive questionnaire or a previous diagnosis of epilepsy were extensively examined by a neurologist and then definitively classified for epilepsy by a panel of senior neurologists. The crude prevalence of active and non-active epilepsy was 3.21/1000; the prevalence of active epilepsy alone was 2.71/1000. Of the 27 active cases, sixteen were affected by generalized tonic-clonic seizures, four by absences and four by complex partial attacks. All except two were being treated with antiepileptic drugs, most with phenobarbital. Our prevalence rate is lower than that reported by most authors, but similar to the rates in other Sicilian communities.

Occupation, education, and Parkinson's disease: a case-control study in an Italian population.

Current epidemiologic data on the association between occupational exposures and Parkinson's disease (PD) are inconsistent. In a case-control study, we investigated the associations between occupation and PD and between education and PD. The cases (n = 62) were those identified in a prevalence survey (door-to-door, two-phase) of three Sicilian municipalities, as a November 1, 1987. We then randomly selected from the general population two controls for each case, matched for age ( +/- year), sex, and municipality (n = 124). Information on current and past occupations and education for cases and controls was obtained during the survey. Subjects who worked for most of their lives as farmers were not at increased risk of PD (OR = 0.6; 95% CI = 0.3-1.3). Neither were subjects who worked for most of their lives in other occupations (e.g., housewives, fishermen, factory workers, salesmen, craftsmen, clerks). PD was not associated with low education. Our findings suggest that farming, as a broad occupational category, does not play a major role in the causation of PD.

Prevalence of cervical spondylotic radiculopathy: a door-to-door survey in a Sicilian municipality.

INTRODUCTION: Because of the limited information on cervical spondylotic radiculopathy, we conducted a door-to-door two-phase survey in a Sicilian municipality. MATERIAL AND METHODS: We first screened for cervical spondylotic radiculopathy among the inhabitants of the municipality: (N = 7653, as of the prevalence day, November 1, 1987). Study neurologists then investigated those subjects suspected to have had a cervical spondylotic radiculopathy. Diagnoses were bases on specified criteria. RESULTS: We found 27 subjects affected by CSR (17 definite, 10 possible). Prevalence (cases per 1000 population) was 3.5 in the total population; it increased to a peak at age 50-59 years, and decreased thereafter. The age-specific prevalence was consistently higher in women. CONCLUSIONS: Comparison with other prevalence studies shows similar age-specific patterns, but different magnitudes, which may partly reflect methodologic differences across studies.

Prevalence of stroke: a door-to-door survey in three Sicilian municipalities. Sicilian Neuroepidemiologic Study (SNES) Group.

As part of a door-to-door survey, we screened for stroke among the inhabitants of three Sicilian municipalities (n = 24,496 as of November 1, 1987). Neurologists then investigated those subjects suspected to have had a stroke. Diagnoses of first-ever strokes were based on specified criteria and were reviewed by an adjudication panel. We found 189 subjects who had experienced at least one completed stroke (180 definite, 9 possible); 15 strokes were hemorrhagic, 71 ischemic, and 103 uncertain. The prevalence (cases/100,000) was 771.6 in the total population and 1,893.6 in those aged 40 years or over. The prevalence increased steeply with age, was higher in men between 60 and 79 years, but was higher in women thereafter. Age-specific figures were similar in the three study municipalities. Although all first-ever strokes had been previously diagnosed, 40% of the subjects had not been hospitalized for this condition.

Risk factors for cerebral glioma in adults: a case-control study in an Italian population.

A case-control study on risk factors for cerebral tumors was conducted on an adult Italian population by the four Neurosurgical Departments of the Veneto Region, i.e. Padua, Treviso, Verona and Vicenza. The study recruited 195 cases of histologically-confirmed cerebral glioma. One hospital control was selected for each case. Cases and controls were matched for age, sex, data of hospitalization and residence. Information on both cases and controls was obtained from a relative. Uninvolved interviewers administered a structured questionnaire including items on the subject's education, occupation, lifestyle, medical history, exposure to radiation for diagnosis or therapy, head trauma and blood group and the medical history of family members. The series of cerebral tumors was first considered as an indistinct set: none of the risk factors examined showed a statistically significant association. A positive association was found with blood group A (OR = 6) when low-grade astrocytomas (n = 41) were considered separately. As for the malignant astrocytomas (n = 132), there was a suggestive but not statistically significant association with the presence of CNS tumors among first- and second-degree relatives (OR = 7.0). On the whole, this study yielded no clear and meaningful association for the various risk factors analyzed.

Prevalence of essential tremor: a door-to-door survey in Terrasini, Sicily. Sicilian Neuro-Epidemiologic Study Group.

As part of a door-to-door neuroepidemiologic survey, we investigated the frequency and distribution of essential tremor (ET) in a Sicilian municipality. During phase 1, we administered a screening instrument for tremor to 7,653 persons residing in Terrasini (Palermo province). During phase 2, neurologists evaluated those subjects who had screened positive. The diagnoses, based on specified clinical criteria, were reviewed to increase reliability across neurologists. We found 31 subjects affected by ET (17 men, 14 women); 11 patients (35.5%) reported a familial aggregation. The prevalence of ET as of November 1, 1987, was 405.1 per 100,000 for the total population, and 1,074.9 per 100,000 for those 40 years old or older. The prevalence increased with advancing age for both sexes and was slightly but consistently higher in men. Comparison with other studies suggests striking geographic variation, which may reflect genetic differences.

Attrition and use of proxy respondents and auxiliary information in the Sicilian Neuroepidemiologic Study.

Two-phase prevalence surveys with screening (phase 1) and examination (phase 2) are useful for some chronic diseases. Attrition, which may bias estimates, occurs in either phase because some eligible subjects die before contact, some refuse to cooperate, some are incapacitated, and some are unreachable. This investigation relates to a survey of neurologic diseases conducted in three municipalities of Sicily (prevalence date, November 1, 1987) and considers the attrition experienced and the use of proxy respondents in phase 1 and auxiliary information in phase 2 to offset, in part, this attrition. Regarding case finding, the salvage effort was more productive for decreased and incapacitated subjects. The age, sex, and household size of the subject were related to phase 1 attrition, but only age was related for all four attrition groups--deceased, refusing, incapacitated, and unreachable subjects. On the basis of information from proxy respondents, the educational levels of refusing and unreachable subjects were compared with those of subjects screened directly. Refusing subjects were less educated, and unreachable subjects were more educated. The proxy respondent performance, as indicated by "don't know" responses, was better with screening items concerning facial paralysis and mouth drooping (and not limb sensory abnormalities or impaired consciousness), better with younger subjects, and worse with refusing or incapacitated subjects.