Nanoscale mapping of heterogeneity of the polarization reversal in lead-free relaxor-ferroelectric ceramic composites.

Relaxor/ferroelectric ceramic/ceramic composites have shown to be promising in generating large electromechanical strain at moderate electric fields. Nonetheless, the mechanisms of polarization and strain coupling between grains of different nature in the composites remain unclear. To rationalize the coupling mechanisms we performed advanced piezoresponse force microscopy (PFM) studies of 0.92BNT-0.06BT-0.02KNN/0.93BNT-0.07BT (ergodic/non-ergodic relaxor) composites. PFM is able to distinguish grains of different phases by characteristic domain patterns. Polarization switching has been probed locally, on a sub-grain scale. k-Means clustering analysis applied to arrays of local hysteresis loops reveals variations of polarization switching characteristics between the ergodic and non-ergodic relaxor grains. We report a different set of switching parameters for grains in the composites as opposed to the pure phase samples. Our results confirm ceramic/ceramic composites to be a viable approach to tailor the piezoelectric properties and optimize the macroscopic electromechanical characteristics.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [(18)F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Psychogenic relapses in childhood epilepsy in puberty and adolescence.

Epileptic patients who, after years of being free from symptoms, have relapses during puberty or adolescence (some-times coinciding with a reduction in therapy) pose special therapeutic and diagnostic problems. Because of pubertal lability, the cause of a relapse might seem to be "organic", especially if the EEG also shows a "deterioration", yet psychogenic factors must not be disregarded. On the basis of typical case studies, a characteristic constellation is presented. The achievement of a "well-behaved" child at first dramatically improves and this correlates with the success of antiepileptic therapy. Then individuation and further development cannot adequately take place because the family unit is not functioning properly. At a critical stage of development, the excessive expectations of the parents lead to too much stress on the child, thus destroying the balance within the family system, which has hitherto been maintained only with difficulty. Attempts to improve the situation by changing the medication (increasing the dose or switching to another drug) fail. If, however, it is realized that the symptoms are of psychogenic origin, adequate therapeutic interventions (e.g. adequate schooling or professional training as well as psychotherapy) promise good results.

A new, small-color-difference equation for dental shades.

Traditionally, dental-shade-guide standards are designated in terms of Munsell hue (H), value (V), and chroma (C). However, delta E color differences proposed as ADA tolerances for shade guides are in the CIE L*a*b* system. The purpose of this study was to evaluate a new color-difference equation, delta EM = C delta H/5 + 7 delta V + 4 delta C for estimation of small color differences by Munsell parameters. The published values of the Bioform shade-guide tooth colors determined with a Beckman spectrophotometer were used. Color differences among 276 combinations of the 24 Bioform shade-guide colors were calculated with Eq. 1, with use of the Munsell notation, and also with the CIE L*a*b* equation for delta E. An estimate of the accuracy of Eq. 1 was 0.41 delta E units when delta E CIE was below 4.0. The Vita shade-guide colors were determined with a Beckman spectrophotometer. This data set contained 16 samples, and 120 combinations were used for calculation of color difference. An estimate of the accuracy for this set of data was 0.35 delta E units when delta E CIE was less than 4.0. The new color-difference equation provides a means for estimation of delta E CIE L*a*b* color difference between dental shades with Munsell notation. This equation will be useful for estimation of small delta E CIE L*a*b* values for shade-guide teeth that are designated in terms of Munsell notation.

Prognosis of childhood epilepsy in newly referred patients.

The aim of this study was to investigate the prognosis of childhood epilepsy and to analyze prognostic factors in addition to remission rate in a follow-up of newly referred patients. Two hundred eighty-one patients were followed for a mean period of 5.3 years. Overall, 253 patients (90%) achieved 1-year remission. The beginning of a 1-year seizure-free period was achieved in 77.9% by 1 year, in 84% by 2 years and in 88.6% by 3 years after onset of treatment. Early onset of seizures, symptomatic etiology, and neurologic handicap predicted a worse prognosis. In 44 of 253 children with complete suppression of seizures for 1 year, relapses occurred within the follow-up period. In one child with a relapse, remission could not be achieved in the 2nd year thereafter. In conclusion, our study shows a good prognosis for most children with epilepsy, especially in patients with idiopathic epilepsy and late onset of seizures and without neurologic dysfunction. Moreover, our data strongly suggest that the long-term pattern of seizure control is largely established during the first 2 years of treatment.

Carbamazepine and benzodiazepines in combination--a possibility to improve the efficacy of treatment of patients with 'intractable' infantile spasms?

Therapeutical efforts in epilepsies with infantile spasms (IS) often show unsatisfying results, especially if neurological impairments are found. In a clearly negatively selected group of 24 children with IS and 10 patients with symptomatic myoclonic-astatic epilepsies--pretreated without success with ACTH and/or benzodiazepines (BDZ) alone or combined with other anticonvulsants--we tried a two-drug therapy of BDZ with carbamazepine (CBZ). Dosage of both drugs was within the usual range. In a follow-up period of 1-5 years, 8 of the IS patients and 4 of those with myoclonic-astatic seizures became seizure-free; furthermore, 6 children showed a marked reduction in their seizure frequency: 3 more than 80%, 3 more than 50%. Besides the fact that the patients did not develop a so-called escape-phenomenon--as often seen in therapy with benzodiazepines--they also showed fewer and less intensive side-effects. Without optioning for antiepileptic polytherapy in general, we conclude that in cases of "intractable" IS the combination of BDZ with CBZ might be more successful than the single drug. To confirm these preliminary findings further controlled studies have to be carried out.

One-dimensional color order system for dental shade guides.

The purpose of this study was to re-arrange the master Bioform shade guide into a long-range one-dimensional color system based upon color difference. Although most shade guides may show local order when arranged according to hue, long-range order has not been established. However, shade guide arrangement according to a logical color order would be an advantage to the user. The first step in determining the color order was to measure the color of the shade guide teeth. A methodology was developed for measuring the color by use of a reflectance spectrophotometer. The precision of measurement was determined to be equal to CIE L*a*b* delta E of 0.5. Spectra were obtained and converted into CIE L*a*b* and Munsell notation. The measured colors of the Bioform shades ranged from a Munsell hue of 0.9 Y to 3.5 Y; a value of 6.6 to 7.8; and a chroma of 1.9 to 4.1. The teeth were then arranged visually from light to dark. The correlation coefficient between the visual ranking and color difference was 0.95. There was an inverse correlation between visual ranking and Munsell value, with a correlation coefficient of 0.90. Therefore, the sequence according to color difference provided the better agreement with visual perception.

Stress induced phase transformation of a cesium stabilized leucite porcelain and associated properties.

OBJECTIVES: The addition of CS2O to dental porcelains might provide a means for controlling the thermal expansion and toughness of feldspathic porcelains. The purpose of this investigation was to determine for a leucite porcelain the effect of CS2O content upon its coefficient of thermal expansion (alpha), toughness, hardness, and content of low (tetragonal) leucite and high (cubic) leucite. METHODS: In order to determine the amount of low leucite in the specimens, an x-ray calibration curve for low leucite and an internal standard of copper was obtained using quantitative x-ray diffraction techniques. Utilizing a stress induced phase transformation between low and high leucite, an x-ray intensity conversion ratio (r) was determined for high leucite so that the calibration curve for low leucite could be used to determine the amount of high leucite present in the experimental porcelains. Specimens were prepared with various amounts of CS2O (0.0, 0.5, 1.0, 1.5, 2.0 mol%) so that, except for the as-received porcelain (A), all had the same thermal history. Specimens were tested for content of low and high leucite, hardness (Vickers), toughness (indentation-strength method), and coefficient of thermal expansion (alpha) over two temperature ranges (30-500 degrees C and 30-640 degrees C). Fractured surfaces were examined with a scanning electron microscope (SEM). For each property, specimen groups were compared for statistical differences. These comparisons were statistically analyzed using analysis of variance (ANOVA) and Fisher's protected least significant differences (PLSD). RESULTS: Quantitative x-ray examination of abraded and heat-treated specimens demonstrated that a stress induced phase transformation occurred which could be reversed by heat treatment. The conversion ratio was determined as r = 1.93 +/- 0.29. The addition of CS2O lowered the wt% of low leucite from 63 +/- 6% to 0% and increased the amount of high leucite from 0% to 62 +/- 5%. ANOVA showed that the addition of CS2O had a significant effect on alpha (p < 0.0001), hardness (p < 0.005), and toughness (p < 0.0001). CS2O significantly (PLSD) lowered the alpha (p < 0.0001), hardness (p < 0.01), and toughness (p < 0.0001) of a high-content leucite porcelain. SIGNIFICANCE: A stress induced phase transformation of high leucite to low leucite was demonstrated and, as a consequence, suggested the potential for phase transformation toughening. The alpha of a leucite porcelain could be controlled by stabilizing high (cubic) leucite to room temperature with the fraction of high leucite dependent upon the amount of CS2O added. A method was developed to determine the amount of high leucite present in a porcelain.

Sources of color variation on firing porcelain.

The final color matching of porcelain crowns depends upon the accuracy of the original shade matching by the dentist and variables introduced during processing. Possible sources of processing variables include thickness and color of the opaque, thickness, color, and translucency of the body and enamel layers, firing temperature, and number of firings (Miller, 1987). These processing variables can lead to an error in shade match. The purpose of this study was to quantify, in CIE delta E units: (1) the shade variations when the same batches are fired, (2) the shade variations between different batches, and (3) the differences in color produced by the multiple firing. Three lots of six shades of four commercial brands were included in this study. The color variation of the opaque samples (mean delta E was 0.46) was generally lower than that of the body/opaque samples (mean delta E was 0.86). The average color variation for three different batches of the body/opaque samples was 1.44. The average color difference produced as a result of multiple firings was 1.00 after six firings, compared with the color after three firings.

The strengthening mechanism of a magnesia core ceramic.

A high-expansion core material containing magnesia and forsterite may be used to make all-ceramic dental crowns with porcelain-fused-to-metal body porcelains. The purpose of this study was to investigate the strengthening mechanism for the magnesia core material. Six batches of the magnesia core material were made by reacting magnesia with a silica glass with holding times ranging from 17 to 120 min. The flexural strength was measured using three-point loading according to the ISO specification for dental ceramics. The forsterite content was measured using quantitative x-ray diffraction. A statistically significant correlation was found between the forsterite content and flexural strength. The proposed mechanism for strengthening is the precipitation of fine forsterite crystals in the glass matrix surrounding unreacted magnesia. Longer reaction times produced more dissolution of magnesia and subsequent precipitation of forsterite. This method results in a new strengthening mechanism for dental ceramics which have previously relied on the incorporation of alumina, leucite or ceramic whiskers.

Color distribution of three regions of extracted human teeth.

OBJECTIVES: Knowledge of human tooth color and its distribution are critical to the understanding of shade matching in esthetic dentistry. The color of human teeth shows a gradation from the gingival to the incisal region. There have been many reports in the literature on the distribution of color in teeth, but not in the CIE 1976 L*a*b* system. This study was conducted to determine the color distribution in three regions in a sample of human teeth and express the results in Munsell notation, CIE 1976 L*a*b* and CIE delta E* color differences. The hypothesis of this research was that it is possible to detect significant differences in the color parameters of the three distinct regions in teeth. METHODS: All of the teeth used in this study were extracted, cleaned and stored in artificial saliva. Prior to measurement, the teeth were removed from the solution and mounted in a holder to ensure consistent measurements. Spectral data were collected using a GE recording spectrophotometer, CIE chromaticity coordinates calculated using CIE illuminant C and 1931 observer data, and conversions made to L*, a*, b* and Munsell notation. The results were analyzed by ANOVA and Scheffé's multiple comparisons test. RESULTS: The mean L*, a*, b*s were 72.6, 1.5, 18.4 for gingival, 72.4, 1.2, 16.2 for middle, and 71.4, 0.9, 12.8 for incisal. Average Munsell parameters were 1.2 Y 7.1/2.7 for gingival, 1.3 Y 7.1/2.4 for middle, and 1.4 Y 7.0/1.9 for incisal. The mean CIE delta E* between the gingival and incisal regions of the 95 teeth showed a clinically significant difference of 8.2. SIGNIFICANCE: The distribution of color was identified for three regions of the tooth. A statistical analysis determined that there are statistically significant color differences between the regions, and these differences are also clinically significant. This information is beneficial when esthetic restorations are required.

Cerium oxide as a silver decolorizer in dental porcelains.

OBJECTIVES: Silver-base alloys are known to produce an esthetically unpleasant yellow-green tint in the dental porcelain when making PFM restorations. Cerium oxide is used in dental porcelains to simulate the natural fluorescence found in human dental enamel, and has also been used in the glass industry as a decolorizer. The purpose of this study was to determine the effect of CeO2 additions on the resistance of dental porcelain to staining from silver contamination. METHODS: Five batches of porcelain were prepared according to Weinstein et al. (1962) with 0.00, 0.05, 0.10, 0.15 and 0.20 wt% additions of CeO2. To determine the resistance of these porcelains to silver staining, 0.10 wt% additions of the silver oxides were triturated into the prepared CeO2 porcelains prior to sample fabrication. This procedure provided a more quantitative method of staining than firing directly on silver alloys. Silver oxide was added in two valence states as Ag2O and AgO to test for any possible effects on staining. Samples were pressed into a 17 mm diameter mold, and fired to 960 degrees C under vacuum. Three additional samples were prepared from the non-cerium porcelain frit to produce a non-stained control group. Color measurements were made with a spectrophotometer on the ten experimental groups and the control group. The CIE L*a*b* color difference, delta E*, was calculated between the control and the experimental groups. RESULTS: There was a significant decrease in the silver staining of dental porcelains when CeO2 additions of 0.10 wt% or greater were used. SIGNIFICANCE: Cerium oxide additions in the range of 0.10 to 0.20 wt% caused a three-fold reduction in the staining of dental porcelain samples which had been doped with 0.10 wt% of AgO or Ag2O.

[Determination of antiepileptic drug levels in the blood: day-to-day experience in an out-patient clinic for epilepic children (author's transl)]. / Blutspiegelbestimmungen von Antiepileptika--Erfahrungen aus der Praxis einer Anfallsambulanz.

The possibility of determining the blood levels of antiepileptic drugs represents a considerable advance, under certain circumstances, objective supervision of anticonvulsant therapy. In particular in the case of an unsatisfactory therapeutic result, this procedure helps to reveal the causes of failure (e.g. incorrect administration, poor absorption, interaction with other drugs). Like many new diagnostic methods this method is rather costly; hence, its use within the daily routine work should be limited to definite indications. Apart from its use in cases of inadequate control of epilepsy and the appearance of side effects, other indications for implementation of the method are the establishement of correct dosation of antiepileptic drugs in new patients and drug intercurrent illness, which frequently necessitates the use of additional drugs.

[Brain damage and epilepsy in childhood (author's transl)]. / Epilepsie und Schädelhirntrauma im Kindesalter

Among the 1100 patients with convulsive disorders attending out-patient paediatric clinics of the Universities of Vienna and Graz, there are 14 cases of postnatal posttraumatic epilepsy. The characteristic features of this condition, as evidenced even by this small group of patients are focal epilepsy with focal paroxysms in the EEG, often combined with neurological defects and psychological abnormalities, but more seldom with defects of intelligence; resistance to anticonvulsive drugs is a frequent observation. In a retrospective study such as this, the criteria which could predict the development of epilepsy following posttraumatic brain damage are not sufficiently accurately definable; prospective serial studies on brain-damaged children would be of greater prognostic value. The following parameters seem to be important: the kind of brain damage, the duration of unconsciousness, the frequency of initial convulsive attacks and the persistance of the progression of the EEG changes.

[Computerized tomography in epilepsy in children]. / Computertomographie bei Epilepsien im Kindesalter.

We present a retrospective study of 160 children attending our epilepsy out-patient department. Computed tomography (CT) was performed on 123 (77%) patients, namely all children with the exception of those with febrile seizures, typical absence seizures, and benign Rolandic epilepsy. Incidence of CT abnormalities and their correlation with clinical features were evaluated. The CT scan was normal in 84 and abnormal in 39 patients. Although in general, the detection of abnormality on CT will not alter the management of the child, in a small percentage (2%) of our cases a lesion treatable by surgery was discovered. The indications for CT are summarized.

[Psychosocial dwarfism--a rare form of growth disorder]. / Psychosozialer Minderwuchs--eine seltene Form der Wachstumsstörung.

Psychosocial dwarfism is a syndrome caused by emotional deprivation (maternal deprivation), characterized by symptoms of delayed motor and intellectual development, abnormal eating and drinking habits, enuresis and encopresis, aggressiveness and a pathological family structure. Diagnosis of psychosocial dwarfism is easy if the case history is carefully elicited and the growth hormone level is determined within the first few days following change in environment (e.g. hospitalization). Difficulty in reaching the correct diagnosis or misdiagnosis can occur if the symptomatology is not studied in its entirety. Diagnosis at the earliest possible stage is very important for the further development of the child, since behavioural disturbances and growth retardation are reversible with environmental change. This is demonstrated by the presentation of the case history of a 6 year-old boy--the third case reported in the German literature.

[Discrimination between epileptic and non-epileptic seizures using defined prolactin studies]. / Diskriminierung epileptischer und nichtepileptischer Anfälle mittels genormter Prolaktinuntersuchungen.

Prolactin blood levels (HPRL) increase within 20 minutes postictally after generalized epileptic, especially generalized tonic-clonic seizures and return to normal values within one hour. Elevated HPRL levels were also observed after complex partial seizures, but usually in less extent, exceeding normal ranges only slightly. Therefore baselin HPRL measurements are necessary for estimation of spontaneous fluctuations in comparison to changes after seizures. Unchanged PRL levels after attacks do not support their epileptic origin. Rage attacke showed no clear pattern of PRL changes.

[Function and structure of families with an epileptic child]. / Funktion und Struktur von Familien mit einem epilepsiekranken Kind.

Although the impact of psycho-social factors on the individual patient with epilepsy has been widely investigated, the influence of the illness on the family as a whole is still underestimated. By means of the Family Assessment Measure (FAM III), a well-validated instrument, we investigated which measurable influence the epilepsy of one child had on the functioning of the families. Data from a group of 72 families with a child suffering from epilepsy (EG), but without any other handicap were analysed and compared with those of 75 families with a child with severe mental retardation (SMG) and 76 control families (CG). Data were gathered through home visits. Only complete families were studied. Results showed that the EG was similar to the SMG in all 3 scales of FAM III, but differed significantly from the CG. In 26% of the families in EG and in 19% of the SMG clear signs of family malfunctioning were found, as compared with 6.5% of the CG. Family disfunctioning in EG was of a greater variety that in SMG. We found that within the EG the type of seizures (41 patients with generalized tonic clonic fits, 10 with complex partial seizures and 21 with absences) did not have any impact on the results. In addition, neither the duration of the illness nor the absolute length of seizure-free periods seemed to matter. Only families who had the subjective feeling that their children were still suffering from epilepsy showed significantly higher rates of family malfunctioning. Summarizing, we found that epilepsy in a child can have a severe impact, not only on his individual life and on the mother-child relationship, but on the functioning of his family as the whole. This fact should be taken into account in the treatment of these children and should influence family counselling, as well.

[A discussion of the curability of childhood epilepsies (author's transl)]. / Zur Frage der Heilbarketi kindlicher Epilepsien

Permanent freedom from fits can be achieved in a large proportion of children with a history of epilepsy through precise individual adjustment and careful maintenance of the therapeutic regimen. A review of the cases treated at the Pediatric Clinic, out-Patient-Department for Epileptics, University of Vienna, reveals that at present about 70% of the patients have a good prognosis (the figures vary from 50 to 85%, depending on the seizure type). An important question which has received only scant attention in the literature arises in the case of patients who have remained free from epileptic fits over a period of many years, namely whether longterm antiepileptic therapy can be terminated and, if so, then when and how. Only very few studies deal specifically with this problem and even these do not provide entirely satisfactory answers to all the posed questions, not only with regard to the optimum time and mode of drug reduction, but also with regard to the principles underlying the choice of apparently suitable candidates for attempted termination of therapy. An attempt is made in this retrospective study comprising 375 patients who have been followed up over a period of at least 5 years, to throw some light on these problems. Indeed, results of statistical significance were obtained by the use of a new mathematical technique, which enables the formulation of new guiding principles in the resolution of all three above-mentioned questions. In consequence, it now appears within the power of the pediatrician to markedly reduce the risk of relapse, which in the case of childhood epilepsies, is about 20%, at present. In general, several basic principles must be adhered to. Total freedom from convulsions over an uninterrupted period of at least 3 years' duration is an absolute prerequisite for consideration of cessation of therapy. Reduction in antiepileptic drug dosage should be carried out as a stepwise procedure over a period of about 2 years. Regular clinical and EEG follow-up examinations should be performed over this period of drug reduction and for 5 years subsequently, in order to recognise and counteract promptly any early signs of possible relapse. The prerequisite convulsionfree period is raised to 4 to 5 years or even longer and the time over which therapy is tailed off increased accordingly in the presence of any of the following criteria: 1. "Endogenous" tendency to relapse, 2. persistence of paroxysmal EEG abnormalities or deterioration of the EEG during the attempt to reduce the dosage of antiepileptic drugs, 3. inveterate epilepsy. The cessation of fits and the termination of medication do not yet signify that all the after-effects of epilepsy are overcome. Social integration must also be achieved before this goal is reached. The psychopathological symptomatology of the patient plays an important role in determining the outcome, whereby the level of intelligence of the patient is the decisive factor...

[Improved properties of systems for computer-assisted motility analysis]. / Verbesserung der Eigenschaften von Systemen der computerunterstützten Motilitätsanalyse.

For a number of years, computer-assisted methods have been employed for the motility analysis of spermatozoa. In addition to a number of advantages, such as short processing time and good reproducibility, they have certain shortcomings in the recognition and tracking of spermatozoa at high densities. For example, sperm cells and contaminating particles of the same size cannot be distinguished. The tracking of crossing sperm cell trajectories is also a problem. For this reason, procedures that are free from such shortcomings have been introduced. Their application leads to an improvement in the performance of computer-assisted semen analysis methods.