RESUMEN
The performance assessment of storage tanks and combined sewer overflow (CSO) structures in sewer systems requires knowledge of the total inflow from the catchment during rainfall events. Many structures are, however, only equipped with sensors to measure water level and/or outflows. Based on the geometry of the tank, expressed as a level-storage relationship, inflow can be calculated from these data using a simple conceptual storage model. This paper compares a deterministic and a Bayesian approach for estimating the inflow to a CSO structure from measurements of outflows and water level. The Bayesian approach clearly outperforms the deterministic estimation which is very sensitive to measurement errors. Although computationally more demanding, the use of a simple linear storage model allows the online application of the Bayesian approach to repeatedly estimate inflow in short time intervals of a few minutes. The method could thus be used as an online software sensor for inflow to storage structures in sewer systems.
RESUMEN
For a sufficient calibration of an environmental model not only parameter sensitivity but also parameter identifiability is an important issue. In identifiability analysis it is possible to analyse whether changes in one parameter can be compensated by appropriate changes of the other ones within a given uncertainty range. Parameter identifiability is conditional to the information content of the calibration data and consequently conditional to a certain measurement layout (i.e. types of measurements, number and location of measurement sites, temporal resolution of measurements etc.). Hence the influence of number and location of measurement sites on the number of identifiable parameters can be investigated. In the present study identifiability analysis is applied to a conceptual model of a combined sewer system aiming to predict the combined sewer overflow emissions. Different measurement layouts are tested and it can be shown that only 13 of the most sensitive catchment areas (represented by the model parameter 'effective impervious area') can be identified when overflow measurements of the 20 highest overflows and the runoff to the waste water treatment plant are used for calibration. The main advantage of this method is very low computational costs as the number of required model runs equals the total number of model parameters. Hence, this method is a valuable tool when analysing large models with a long runtime and many parameters.
Asunto(s)
Monitoreo del Ambiente/métodos , Modelos Teóricos , Aguas del AlcantarilladoRESUMEN
A new methodology for online estimation of excess flow from combined sewer overflow (CSO) structures based on simulation models is presented. If sufficient flow and water level data from the sewer system is available, no rainfall data are needed to run the model. An inverse rainfall-runoff model was developed to simulate net rainfall based on flow and water level data. Excess flow at all CSO structures in a catchment can then be simulated with a rainfall-runoff model. The method is applied to a case study and results show that the inverse rainfall-runoff model can be used instead of missing rain gauges. Online operation is ensured by software providing an interface to the SCADA-system of the operator and controlling the model. A water quality model could be included to simulate also pollutant concentrations in the excess flow.
Asunto(s)
Monitoreo del Ambiente/métodos , Aguas del Alcantarillado , Programas InformáticosRESUMEN
Functional hemispherectomy, a safe and effective therapeutical procedure in medically intractable epilepsy, offers the chance to investigate a strictly unilateral cortical activation in ipsilateral limb movement. We assessed the pattern of cortical activation in a group of patients following functional hemispherectomy. We measured regional cerebral blood flow (rCBF) in 6 patients postoperatively and 6 normal subjects with positron emission tomography using 15[O]H2O as a tracer. Brain activation was achieved by passive elbow movements of the affected arm. Analysis of group results and between-group comparisons were performed with statistical parametric mapping, (SPM96). In normal subjects brain activation was found contralaterally in the cranial sensorimotor cortex and the supplementary motor area and ipsilaterally in the inferior parietal cortex. In patients significant rCBF increases were found in the inferior parietal cortex, caudal sensorimotor cortex and the supplementary motor area ipsilaterally. The activation was weaker than in normal subjects. Compared with normal subjects patients showed additional activation in the premotor cortex, caudal sensorimotor cortex and the inferior parietal cortex of the remaining hemisphere. Less activation compared with normal subjects was found in the cranial sensorimotor cortex and the supplementary motor area. A functional network connecting the inferior parietal cortex, premotor cortex and the supplementary motor area as well as the existence of ipsilateral projections originating from these regions may explain why these areas are predominantly involved in reorganization confined to a single hemisphere.
Asunto(s)
Encéfalo/cirugía , Corteza Cerebral/fisiología , Procedimientos Neuroquirúrgicos , Adulto , Mapeo Encefálico , Corteza Cerebral/diagnóstico por imagen , Epilepsia/cirugía , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Corteza Motora/diagnóstico por imagen , Corteza Motora/fisiología , Movimiento/fisiología , Paresia/cirugía , Corteza Somatosensorial/diagnóstico por imagen , Corteza Somatosensorial/fisiología , Tomografía Computarizada de EmisiónAsunto(s)
Anestésicos Locales/farmacología , Carticaína/farmacología , Lidocaína/farmacología , Ataxias Espinocerebelosas/tratamiento farmacológico , Anestésicos Locales/uso terapéutico , Bloqueadores de los Canales de Calcio/farmacología , Carticaína/uso terapéutico , Humanos , Lidocaína/uso terapéutico , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
We investigated the cortical activation pattern in a 30-year-old woman 4 years after multiple subpial transection (MST) of the right fronto-parietal cortex and six healthy controls using positron emission tomography. Sequential finger-to-thumb opposition at the frequency of 1.5 Hertz contralateral to the operated hemisphere was used as the activation paradigm. We found preserved cortical activation in the transected fronto-parietal cortex and additional activation of the prefrontal cortex bilaterally and the inferior parietal cortex contralaterally when compared with the control group. This activation pattern indicates that MST induces a rather selective lesion leaving the cortical structures functionally intact. However, it necessitates the recruitment of additional motor areas.
Asunto(s)
Epilepsia/fisiopatología , Epilepsia/cirugía , Corteza Somatosensorial/fisiopatología , Corteza Somatosensorial/cirugía , Adulto , Velocidad del Flujo Sanguíneo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Corteza Motora/fisiopatología , Corteza Motora/cirugía , Piamadre/cirugía , Corteza Prefrontal/fisiopatología , Corteza Prefrontal/cirugía , Corteza Somatosensorial/irrigación sanguínea , Tomografía Computarizada de EmisiónRESUMEN
BACKGROUND: Transcranial magnetic stimulation (TMS) was utilized to study 7 patients who had undergone hemispherectomy for control of longstanding intractable epilepsy to assess cortical motor reorganization and MEP (motor evoked potentials) ipsilateral to the remaining hemisphere. Five patients were seizure-free post-operatively. All patients displayed a spastic hemiparesis, were able to walk, raise and bend the paretic arm and use the paretic hand to different degrees. METHODS: We examined MEP threshold, site of maximal response to TMS, and latency to the biceps brachii, abductor pollicis brevis and the anterior tibial muscles using a 7 and 12 cm diameter round coil. RESULTS: The following results were obtained: (1) No MEP could be induced to either side by use of the small coil. (2) When using the large coil MEP-threshold was elevated also when stimulating the non-affected hemisphere in comparison to normal controls. (3) Ipsilateral MEP were found to: be non-inducible in two patients, demonstrate largely increased latencies in 3 and be identical to contralateral MEP in two patients. (4) Ipsilateral MEP could be evoked more often in distal than proximal muscles. (5) The site of maximal ipsilateral MEP response was found approximately 2 cm anteriorly to that of the contralateral MEP to the non-affected side of the body (6) No correlation was found between the degree of hemiparesis and inducability of MEP. CONCLUSIONS: The pattern of reorganization of ipsilateral motor control following early brain damage and hemispherectomy appears to be extremely diverse and does not correlate with the degree of neurological impairment.
Asunto(s)
Encéfalo/fisiopatología , Encéfalo/cirugía , Epilepsia/fisiopatología , Epilepsia/cirugía , Potenciales Evocados Motores/fisiología , Estimulación Magnética Transcraneal , Adulto , Mapeo Encefálico , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Factores de TiempoRESUMEN
We used serial positron emission tomography (PET) to study the evolution of functional brain activity within 12 weeks after a first subcortical stroke. Six hemiplegic stroke patients and three normal subjects were scanned twice (PET 1 and PET 2) by using passive elbow movements as an activation paradigm. Increases of regional cerebral blood flow comparing passive movements and rest and differences of regional cerebral blood flow between PET 1 and PET 2 in patients and normal subjects were assessed by using statistical parametric mapping. In controls, activation was found in the contralateral sensorimotor cortex, supplementary motor area, and bilaterally in the inferior parietal cortex with no differences between PET 1 and PET 2. In stroke patients, at PET 1, activation was observed in the bilateral inferior parietal cortex, contralateral sensorimotor cortex, and ipsilateral dorsolateral prefrontal cortex, supplementary motor area, and cingulate cortex. At PET 2, significant increases of regional cerebral blood flow were found in the contralateral sensorimotor cortex and bilateral inferior parietal cortex. A region that was activated at PET 2 only was found in the ipsilateral premotor area. Recovery from hemiplegia is accompanied by changes of brain activation in sensory and motor systems. These alterations of cerebral activity may be critical for the restoration of motor function.
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Encéfalo/fisiopatología , Hemiplejía/fisiopatología , Accidente Cerebrovascular/fisiopatología , Anciano , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Circulación Cerebrovascular , Femenino , Estudios de Seguimiento , Lateralidad Funcional , Hemiplejía/diagnóstico por imagen , Hemiplejía/etiología , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia , Flujo Sanguíneo Regional , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/diagnóstico por imagen , Tomografía Computarizada de EmisiónAsunto(s)
Encéfalo/patología , Cocaína/envenenamiento , Inhibidores de Captación de Dopamina/envenenamiento , Heroína/envenenamiento , Narcóticos/envenenamiento , Síndromes de Neurotoxicidad/patología , Abuso de Sustancias por Vía Intravenosa/complicaciones , Adulto , Humanos , Imagen por Resonancia Magnética , MasculinoRESUMEN
We analyzed the clinical course and neuroradiological findings of ten patients aged 27-46 years, with ischemic stroke secondary to vertebral artery dissection (VAD; n = 8) or internal carotid artery dissection (CAD; n = 2), all following chiropractic manipulation of the cervical spine. The following observations were made: (a) All patients had uneventful medical histories, no or only mild vascular risk factors, and no predisposing vascular lesions. (b) VAD was unilateral in five patients and bilateral in three. VAD was located close to the atlantoaxial joint in all eight patients and showed additional involvement of lower sections in six, as well as temporary occlusion of one vertebral artery in three. (c) Nine of ten patients had brain infarction documented by magnetic resonance imaging or computed tomography. (d) Onset of symptoms was immediately after the manipulation (n = 5) or within 2 days (n = 5). (e) Progression of neurological deficits occurred within the following hours to a maximum of 3 weeks. (f) Maximum neurological deficits were severe in nine of ten patients. (g) Outcome after 4 weeks-3 years included no or mild neurological deficits in five patients, marked deficits in three, persistent locked-in syndrome in one, and persistent vegetative state in one. (h) Informed consent was obtained in only one of ten patients. Thus, patients at risk for stroke after chiropractic manipulation may not be identified a priori. Neurological deficits may be severely disabling and are potentially life threatening.
Asunto(s)
Trastornos Cerebrovasculares/etiología , Manipulación Espinal/efectos adversos , Cuello/inervación , Adulto , Disección Aórtica/etiología , Enfermedades de las Arterias Carótidas/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento , Arteria VertebralRESUMEN
BACKGROUND AND PURPOSE: Cortical reorganization of motor systems has been found in recovered stroke patients. Reorganization in nonrecovered hemiplegic stroke patients early after stroke, however, is less well described. We used positron emission tomography to study the functional reorganization of motor and sensory systems in hemiplegic stroke patients before motor recovery. METHODS: Regional cerebral blood flow (rCBF) was measured in 6 hemiplegic stroke patients with a single, subcortical infarct and 3 normal subjects with the [(15)O]H(2)O injection technique. Brain activation was achieved by passive elbow movements driven by a torque motor. Increases of rCBF comparing passive movements and rest were assessed with statistical parametric mapping. Significant differences were defined at P<0.01. RESULTS: In normal subjects, significant increases of rCBF were found in the contralateral sensorimotor cortex, supplementary motor area, cingulate cortex, and bilaterally in the inferior parietal cortex. In stroke patients, significant activation was observed bilaterally in the inferior parietal cortex and in the contralateral sensorimotor cortex, ipsilateral prefrontal cortex, supplementary motor area, and cingulate cortex. Significantly larger increases of rCBF in patients compared with normal subjects were found bilaterally in the sensorimotor cortex, stronger in the ipsilateral, unaffected hemisphere, and in both parietal lobes, including the ipsilateral precuneus. CONCLUSIONS: Passive movements in hemiplegic stroke patients before clinical recovery elicit some of the brain activation patterns that have been described during active movements after substantial motor recovery. Changes of cerebral activation in sensory and motor systems occur early after stroke and may be a first step toward restoration of motor function after stroke.
Asunto(s)
Isquemia Encefálica/diagnóstico por imagen , Hemiplejía/diagnóstico por imagen , Desempeño Psicomotor/fisiología , Corteza Somatosensorial/fisiopatología , Tomografía Computarizada de Emisión , Anciano , Velocidad del Flujo Sanguíneo , Isquemia Encefálica/complicaciones , Isquemia Encefálica/fisiopatología , Circulación Cerebrovascular , Femenino , Hemiplejía/etiología , Hemiplejía/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Movimiento/fisiología , Pronóstico , Descanso/fisiología , Corteza Somatosensorial/irrigación sanguínea , Corteza Somatosensorial/diagnóstico por imagenRESUMEN
Secondary prevention of transient or permanent cerebral ischemia is performed with antiplatelet drugs, e.g. aspirin, ticlopidine, clopidogrel or dipyridamole. The four substances have different indications and different side effect profiles. Patients with proven or suspected cardiac source of embolism are treated with anticoagulants. Patients with > 70% stenosis of the internal carotid artery and TIA or minor stroke receive carotid endarterectomy in combination with aspirin. Stroke risk is reduced between 20 and 65% by these measures.
Asunto(s)
Infarto Cerebral/prevención & control , Anticoagulantes/efectos adversos , Anticoagulantes/uso terapéutico , Infarto Cerebral/etiología , Terapia Combinada , Endarterectomía Carotidea , Humanos , Inhibidores de Agregación Plaquetaria/efectos adversos , Inhibidores de Agregación Plaquetaria/uso terapéutico , Recurrencia , Factores de RiesgoRESUMEN
BACKGROUND: Little is known about the link between mood, food and metabolic function in Seasonal Affective Disorder (SAD). METHODS: We investigated this link in a combined glucose tolerance-alliesthesia test in eight SAD patients in winter before and after one week light therapy, and in summer. RESULTS: SAD patients exhibited faster post-glucose glycaemic and insulin responses (p <0.05), and increased hedonic ratings of high concentrated sucrose solutions (p <0.035) when depressed in winter than when euthymic (one week after light treatment or in summer). CONCLUSIONS: The rapid glycaemic and insulin responses to an oral glucose load may be a result of accelerated gastric emptying. LIMITATIONS: The number of studied patients was rather small and no control group was studied in parallel. CLINICAL RELEVANCE: the more rapid post-glucose glycaemia may impair glucose homeostasis in depressed SAD patients.
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Afecto , Glucemia/análisis , Trastorno Afectivo Estacional/sangre , Adolescente , Adulto , Apetito , Índice de Masa Corporal , Calorimetría Indirecta/métodos , Carbohidratos de la Dieta/metabolismo , Femenino , Vaciamiento Gástrico , Prueba de Tolerancia a la Glucosa , Humanos , Insulina/sangre , Insulina/metabolismo , Masculino , Fototerapia/métodos , Estudios Prospectivos , Trastorno Afectivo Estacional/terapia , Factores de TiempoRESUMEN
BACKGROUND: There are no controlled studies investigating the response of patients with seasonal affective disorder (SAD) to a total sleep deprivation (SD). METHODS: The clinical response to SD of patients with SAD in winter was investigated under the stringently controlled conditions of a 40-h constant routine protocol. RESULTS: 52% of the SAD patients (N=11 women) improved, using a mean of a multiple ratings. This is in the range of response found for non-seasonal major depression. In contrast, controls (N=8 women) showed less improvement of mood (29%). CONCLUSION: SAD patients respond to SD as do non-seasonal major depressives. The best discrimination of response was obtained in an observer rating (Clinical Global Impression: global severity improvement), and the morning values of two different self ratings (v. Zerssen depression scale, 100 mm VAS with the criterion of > or =10 mm improvement). LIMITATION: A more reliable estimate of the SD response rate in SAD patients would require a larger group. CLINICAL RELEVANCE: SAD patients do not differ from other subgroups of major depression in their response to SD, and therefore this is an additional treatment option to light therapy.
Asunto(s)
Trastorno Afectivo Estacional/psicología , Privación de Sueño , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Fototerapia , Trastorno Afectivo Estacional/diagnóstico , Trastorno Afectivo Estacional/terapia , Índice de Severidad de la Enfermedad , Factores de TiempoRESUMEN
Possible changes in the organization of the cortex in patients with facial palsy, serving as a model of peripheral motor deefferentation, were investigated by using transcranial magnetic stimulation (TMS) and positron emission tomography (PET). With TMS, the size of the area producing muscle-evoked potentials (MEPs) of the abductor pollicis brevis muscle, the sum of MEP amplitudes within this area, and the volume over the mapping area were compared between both hemispheres in 8 patients. With PET, increases in regional cerebral blood flow, measured with the standard H2(15)O2 bolus injection technique, were compared between 6 patients and 6 healthy volunteers during sequential finger opposition. Patients moved the hand ipsilateral to the facial palsy, the control subjects the right hand. Of 9 patients in total, 5 participated in both experiments. With both methods, an enlargement of the hand field contralateral to the facial palsy was found, extending in a lateral direction, into the site of the presumed face area. The PET data showed that the enlargement of the hand field in the somatosensory cortex (SMC) is part of a widespread cortical reorganization, including the ipsilateral SMC and bilateral secondary motor and sensory areas. We report for the first time, using two different noninvasive methods, that peripheral, mere motor deefferentation is a sufficient stimulus for reorganizational changes in the healthy adult human cortex.
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Corteza Cerebral/diagnóstico por imagen , Corteza Cerebral/patología , Parálisis Facial/diagnóstico por imagen , Parálisis Facial/patología , Adaptación Fisiológica , Adulto , Anciano , Mapeo Encefálico , Corteza Cerebral/irrigación sanguínea , Circulación Cerebrovascular , Potenciales Evocados , Parálisis Facial/fisiopatología , Femenino , Dedos/fisiología , Lateralidad Funcional , Humanos , Imagen por Resonancia Magnética , Magnetismo , Masculino , Persona de Mediana Edad , Movimiento/fisiología , Estimulación Física , Corteza Somatosensorial/diagnóstico por imagen , Corteza Somatosensorial/patología , Tomografía Computarizada de EmisiónRESUMEN
During active and passive (driven by a torque motor) flexion and extension of the right elbow, regional cerebral blood flow (rCBF) was measured in six healthy, male volunteers using positron emission tomography and the standard H2(15)O injection technique. During active as well as during passive movements of the right elbow there were strong increases in rCBF, identical in location, amount, and extent in the contralateral sensorimotor cortex. There were activations during both conditions in the supplementary motor area (stronger and more inferior in the active condition) and inferior parietal cortex (on the convexity during active movements and in the depth of the central sulcus during passive movements). During active movements only, activations of the basal ganglia and the cingulate gyrus were found. Brain activations during motor tasks are largely related to the processing of afferent information.
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Mapeo Encefálico , Codo/inervación , Cinestesia/fisiología , Desempeño Psicomotor/fisiología , Tomografía Computarizada de Emisión , Adulto , Lateralidad Funcional/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Corteza Motora/irrigación sanguínea , Corteza Motora/fisiología , Flujo Sanguíneo Regional/fisiología , Corteza Somatosensorial/irrigación sanguínea , Corteza Somatosensorial/fisiologíaRESUMEN
The role of sleep regulation in Seasonal Affective Disorder (SAD) was studied in 11 female SAD patients and eight controls in winter before and after light treatment (LT, 6000 lux, 10-14h, 5 days). The sleep electroencephalogram (EEG) was recorded at baseline and after the total sleep deprivation (TSD) of a 40-h constant routine. The well-known effects of TSD on sleep parameters and on EEG power spectra were replicated, indicating normal homeostatic sleep regulation in SAD. Sleep improved after LT in both groups. Since the condition following LT was the second session, these improvements may be an order effect and/or an effect of LT itself. After LT, sleep EEG spectra of SAD patients, but not of controls, showed modifications resembling those of recovery sleep. Since only SAD patients curtailed their sleep while remitting during the LT period, these EEG modifications can be explained by normal sleep regulation alone. We conclude that the robust antidepressant effect of LT in SAD is unlikely to be mediated by changes in sleep, and that sleep regulatory mechanisms are not a crucial factor in the pathogenesis of winter depression.
Asunto(s)
Electroencefalografía , Fototerapia , Trastorno Afectivo Estacional/fisiopatología , Privación de Sueño/fisiología , Sueño/fisiología , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Polisomnografía , Escalas de Valoración Psiquiátrica , Trastorno Afectivo Estacional/terapiaRESUMEN
Epidemiology focuses on frequency and distribution of diseases and their relevant risk factors. Epidemiologic data are the basis for development of therapeutic strategies, evaluation of prevention and rehabilitation. Stroke in terms of epidemiology includes ischemic brain infarction as well as intracerebral and subarachnoidal hemorrhage. Stroke is most prominent in the elderly with an annual incidence of about 3%. Stroke prevalence varies between 5 and 8%. The 1-year case fatality is about 42%. The mortality rate varies considerably between 20 and 80 per 100 000 in comparable populations in Europe. Hypertension, smoking and atrial fibrillation are the most prominent risk factors; diabetes and the elevated serum cholesterol also contribute.
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Trastornos Cerebrovasculares/epidemiología , Trastornos Cerebrovasculares/etiología , Arritmias Cardíacas/complicaciones , Trastornos Cerebrovasculares/mortalidad , Femenino , Humanos , Hipertensión/complicaciones , Incidencia , Estilo de Vida , Masculino , Prevalencia , Factores de Riesgo , Fumar/efectos adversos , Suiza/epidemiologíaRESUMEN
Seasonal affective disorder (SAD) is characterised by recurrent episodes in autumn and winter of depression, hypersomnia, augmented appetite with carbohydrate craving, and weight gain, and can be successfully treated with bright light. Circadian rhythm hypotheses (summarized in) have stimulated research into the pathophysiology of SAD, postulating that: 1.The illness is a consequence of delayed phase position, 2.It is correlated with diminished circadian amplitude, or 3.It results from changes in the nocturnal duration between dusk and dawn e.g. of low core body temperature or melatonin secretion. Light is considered to act directly on the circadian pacemaker ('Process C') and not on sleep dependent processes ('Process S'). Thus successful treatment of SAD must act via mechanisms within known retinohypothalamic pathways. Conversely, emergence of SAD symptoms may reflect inappropriate neurobiological response to decreasing daylength.