The midpoint of cortical thinning between late childhood and early adulthood differs between individuals and brain regions: Evidence from longitudinal modelling in a 12-wave neuroimaging sample.

Charting human brain maturation between childhood and adulthood is a fundamental prerequisite for understanding the rapid biological and psychological changes during human development. Two barriers have precluded the quantification of maturational trajectories: demands on data and demands on estimation. Using high-temporal resolution neuroimaging data of up to 12-waves in the HUBU cohort (N = 90, aged 7-21 years) we investigate changes in apparent cortical thickness across childhood and adolescence. Fitting a four-parameter logistic nonlinear random effects mixed model, we quantified the characteristic, s-shaped, trajectory of cortical thinning in adolescence. This approach yields biologically meaningful parameters, including the midpoint of cortical thinning (MCT), which corresponds to the age at which the cortex shows most rapid thinning - in our sample occurring, on average, at 14 years of age. These results show that, given suitable data and models, cortical maturation can be quantified with precision for each individual and brain region.

Properties of New Glass-Ionomer Restorative Systems Marketed for Stress-Bearing Areas.

OBJECTIVES: The purpose of this study was to evaluate the properties (fracture toughness, surface hardness) of newer conventional glass-ionomer restorative materials that are marketed for posterior stress-bearing areas compared with more traditional glass-ionomer restorative materials marketed for non-load-bearing areas and composite-resin restorative materials. METHODS AND MATERIALS: Notched-beam fracture toughness specimens were created in a mold with each tested material (Equia Forte, GC America, with and without a surface coating of Equia Forte Coat; Ketac Universal, 3M/ESPE; ChemFil Rock, Dentsply; Fuji IX GP Extra, GC; Ionostar Molar, VOCO; Filtek Z250, 3M/ESPE; Filtek Supreme Ultra, 3M/ESPE) and fractured using a universal testing machine after 24 hours of storage. Hardness values were determined on the surface of the fracture toughness specimens using a hardness tester. Data were analyzed with a one-way ANOVA and Tukey's post hoc test per property (alpha=0.05). RESULTS: The composite-resin restorative materials had significantly greater fracture toughness than the glass-ionomer materials. There was no significant difference in fracture toughness between the glass-ionomer materials. The use of a resin coating significantly increased the surface hardness of the newer glass ionomer marketed for stress-bearing areas. CONCLUSIONS: Fracture toughness was not improved with the newer glass-ionomer restorative materials marketed for stress-bearing areas compared to the conventional glass-ionomer materials, however a resin coating provided greater surface hardness.

Perception and recognition of faces in adolescence.

Most studies on the development of face cognition abilities have focussed on childhood, with early maturation accounts contending that face cognition abilities are mature by 3-5 years. Late maturation accounts, in contrast, propose that some aspects of face cognition are not mature until at least 10 years. Here, we measured face memory and face perception, two core face cognition abilities, in 661 participants (397 females) in four age groups (younger adolescents (11.27-13.38 years); mid-adolescents (13.39-15.89 years); older adolescents (15.90-18.00 years); and adults (18.01-33.15 years)) while controlling for differences in general cognitive ability. We showed that both face cognition abilities mature relatively late, at around 16 years, with a female advantage in face memory, but not in face perception, both in adolescence and adulthood. Late maturation in the face perception task was driven mainly by protracted development in identity perception, while gaze perception abilities were already comparatively mature in early adolescence. These improvements in the ability to memorize, recognize and perceive faces during adolescence may be related to increasing exploratory behaviour and exposure to novel faces during this period of life.

First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers.

We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the Cosmic-Ray Observation via Microwave Emission experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3×10^{16} eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarized emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at E≥10^{17} eV.

Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande.

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8×10(16) eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the "knee" of the cosmic ray spectrum at 3-5×10(15) eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of 10(16) to 10(18) eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.

Suppression of nonradiative recombination by V-shaped pits in GaInN/GaN quantum wells produces a large increase in the light emission efficiency.

Despite the high density of threading dislocations generally found in (AlGaIn)N heterostructures, the light emission efficiency of such structures is exceptionally high. It has become common to attribute the high efficiency to compositional fluctuations or even phase separation in the active GaInN quantum well region. The resulting localization of charge carriers is thought to keep them from recombining nonradiatively at the defects. Here, we show that random disorder is not the key but that under suitable growth conditions hexagonal V-shaped pits decorating the defects exhibit narrow sidewall quantum wells with an effective band gap significantly larger than that of the regular c-plane quantum wells. Thereby nature provides a unique, hitherto unrecognized mechanism generating a potential landscape which effectively screens the defects themselves by providing an energy barrier around every defect.

Spectroscopy of the conformational disorder in molecular films: tetracosane and squalane on Pt(111).

The spectroscopic investigation of the molecular vibrations of adsorbed branched and unbranched alkane molecules using helium atom scattering (HAS) provides evidence for the thermal formation of gauche defects in tetracosane (C24H50) monolayers above 200 K. HAS results for the vibration of tetracosane molecules perpendicular to the Pt(111) surface reveal a strong frequency decrease and peak broadening above the transition temperature which can be related to a reduction of the force holding the molecules to the surface. This reduction of the force is interpreted as being due to the thermal formation of gauche defects within the tetracosane molecules.

Intramolecular diffusive motion in alkane monolayers studied by high-resolution quasielastic neutron scattering and molecular dynamics simulations.

Molecular dynamics simulations of a tetracosane (n-C24H50) monolayer adsorbed on a graphite basal-plane surface show that there are diffusive motions associated with the creation and annihilation of gauche defects occurring on a time scale of approximately 0.1-4 ns. We present evidence that these relatively slow motions are observable by high-energy-resolution quasielastic neutron scattering (QNS) thus demonstrating QNS as a technique, complementary to nuclear magnetic resonance, for studying conformational dynamics on a nanosecond time scale in molecular monolayers.

[Radiotherapy of malignant melanoma of the skin]. / Strahlentherapie des malignen Melanoms der Haut.

The malignant melanoma is presently regarded as a radiosensitive tumor. Usually the first choice treatment for primary melanomas is surgery. However, we regard operation and radiotherapy of primary melanomas of the face up to a thickness of 1 mm as equal therapeutic methods in patients who are sixty years and older. Radiotherapy can be recommended for primary melanomas of the face with higher tumor thickness or in younger patients if a major operations is too burdensome due to impaired general health or internal diseases or if the patient refuses the operation. Radiotherapy of primary melanomas of the scalp can be considered if the patient can accept the irreversible hair loss in the irradiated field. Soft x-ray therapy with single doses of 3.5-5 Gy 3-6 times weekly and total doses of 80 Gy for invasive primary melanomas and 70 Gy for in-situ melanomas has been effective. We choose a half value depth of at least 2.8 mm. The safety margin are 1 cm for in-situ melanomas, and for invasive primary tumors it should be the same as used in surgery: 1 cm for < or = 1 mm, 2 cm for 1-4 mm and 3 cm for > or = 4 mm thick lesions. Prior to soft x-ray therapy the diagnosis should be confirmed and the tumor thickness determined by a representative biopsy. If possible, nodular parts of the tumor should be totally excised. The subsequent soft x-ray therapy can then be performed with a minor half dose depth. Smaller primary melanomas may be totally excised before radiotherapy so that only the safety margin has to be irradiated. Pigment may be visible in the irradiated field up to one year after the end of radiotherapy. Melanoma metastases can be treated by radiotherapy if they grow rapidly or cause symptoms. Pain due to bone metastases is relieved or totally eliminated by this treatment. Excessively high single doses are not necessary for the radiotherapy of melanoma metastases. An adjuvant radiotherapy after excision of regional lymph node metastases does not influence the overall survival and the local recurrence rate and can therefore not be recommended.

Should adjuvant radiotherapy be recommended following resection of regional lymph node metastases of malignant melanomas?

BACKGROUND: Several authors have recommended adjuvant radiotherapy following resection of regional lymph node metastases in cutaneous malignant melanoma. There is, however, little evidence from controlled trials that patients benefit from this treatment. OBJECTIVES: To evaluate the usefulness of adjuvant radiotherapy following resection of lymph node metastases in cutaneous malignant melanoma. METHODS: We performed a retrospective study comparing 58 patients who underwent radiotherapy following resection of regional lymph node metastases with 58 controls from another centre who exclusively underwent regional lymphadenectomy. Patients and their controls were matched with respect to the number of tumour-bearing lymph nodes (1 vs. > 1) and to gender, although the proportion of thick tumours was greater in the irradiation group. RESULTS: The overall survival curves were almost identical in the two groups. There were nine disease recurrences in the study group and 12 in the control group (not significant). Regional recurrences in the irradiated patients were usually accompanied by metastases at other sites. CONCLUSIONS: The present study does not support the recommendation of adjuvant radiotherapy following resection of regional lymph node metastases in patients with malignant melanoma.

Filter matrix estimation in automated DNA sequencing.

In four-color fluourescence-based automated DNA sequencing, a 4 x 4 filter matrix parameterizes the relationship between the dye-intensity signals of interest and the data collected by an optical imaging system. The filter matrix is important because the estimated DNA sequence is based on the dye intensities that can only be recovered via inversion of the matrix. In this paper, we present a calibration method for the estimation of the columns of this matrix, using data generated through a special experiment in which DNA samples are labeled with only one fluorescent dye at a time. Simulations and applications of the method to real data are provided, with promising results.

A method to determine the filter matrix in four-dye fluorescence-based DNA sequencing.

In a previous paper (Yin et al., Electrophoresis 1996, 17, 1143-1150), an automated method for matrix determination in four-dye fluorescence-based DNA sequencing was presented. As a continuation of that work, we have developed an alternative method to estimate the matrix from raw sequence data. The method uses an iterative clustering technique to associate each 4 x 1 data vector with one column of the desired filter matrix, using Kullback's I-divergence as a distance measure. The method requires less preprocessing of the data and less computation than the approach described by Yin et al. (Electrophoresis 1996, 17, 1143-1150). An example demonstrating applicability of the proposed method to Applied Biosystems sequencer data is given.

[Salmonella in broiler intestines in relation to flooring system]. / Salmonella im Broilerdarm in Abhängigkeit von der Bodentechnik.

Broilers were reared on two flooring systems: conventional litter (wood shavings) and plastic floor ("trampoline") without litter. Female birds were housed over 49 d (20 birds per m2), males over 70 d (10 birds per m2). After slaughtering the guts were sampled and deep frozen. Guts of 84 birds from litter floor and 94 birds from plastic floor were examined for Salmonella. Totally, 20% of the guts were Salmonella negative. The plastic floor did not significantly diminish the occurrence of Salmonella. Also not significant in both flooring systems was the higher amount of negative samples after 49 d than after 70 days. Data show, that the amount of Salmonella in the guts of birds from plastic-floor might have been lower than those from litter-floor, in the samples from plastic-floor the amount of Salmonella after 49 days might have been lower than in those after 70 days rearing. The isolates were S. virchow and S. enteritidis.

Aberrant projection induced by otocyst removal maintains normal tonotopic organization in the chick cochlear nucleus.

Nucleus magnocellularis (NM), a second-order nucleus in the chick auditory system, is topographically and tonotopically organized. The basilar papilla (cochlea) projects onto the ipsilateral NM via the auditory nerve. The anteromedial region of NM is innervated by the proximal end of the basilar papilla and responds to high-frequency sounds; more posterolateral regions receive input from more distal locations along the papilla and respond to progressively lower frequencies. NM projects exclusively to the third-order neurons of nucleus laminaris (NL). Otocyst removal prevents the formation of the ipsilateral cochlea and cochlear nerve and results in the development of an aberrant functional projection from the contralateral NM to the "deafferented" NM on the operated side of the brain (Jackson and Parks, 1988). In the present experiment, the otocyst was removed unilaterally and the tonotopic organization of the deafferented NM was physiologically mapped at 17-18 d of embryonic age (E17-E18). Quantitative analyses revealed that the frequency organization of the deafferented NM is almost identical to that in normal embryos. Progressively higher characteristic frequencies were recorded at successively more anterior and more medial locations in the nucleus, and the orientation of the tonotopic axis was indistinguishable from normal. Furthermore, the correlation between characteristic frequency and anatomical location is comparable in the deafferented (r = 0.91) and normal (r = 0.87) NM. The only noticeable discrepancy is that characteristic frequencies in NM on both sides of the brain of operated embryos are higher than the frequencies observed previously at comparable regions of the nucleus in unoperated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Data acquisition system for maximum-likelihood analysis of electron microscopic autoradiographs.

EMAMAP is a program for the data acquisition phase of maximum-likelihood analysis of electron microscope autoradiographs. This program is written in C and has been implemented on a Masscomp MC-500 which supports a graphics processor and a digitizing tablet. The image analysis is automated at a low level: the program operator outlines the edges of the structures of interest using the digitizing tablet, while contiguous regions formed by closed contours are automatically filled by the software. The resulting image is compressed for efficient storage by a quadtree encoding technique for which data compression ratios of greater than 25:1 have been achieved. In practical terms, this implies that the data from a typical experiment of 50 autoradiographs could be stored on a single floppy disk. The system is currently in use for acquiring actual biological experimental data.

Diamine oxidase in the diagnosis of ruptured fetal membranes.

Diamine oxidase activity is present in amniotic fluid but absent from vaginal secretions, providing a method for diagnosing rupture of membranes. Vaginal secretions were absorbed onto sterile paper strips, eluted, and assayed for diamine oxidase activity. Interfering substances included maternal serum, iodine antiseptics, and large amounts of meconium. Two of 109 prenatal clinic (negative control) specimens displayed measurable diamine oxidase activity; one of 144 postamniotomy (positive control) specimens had no diamine oxidase activity. Of 75 test specimens obtained by speculum examination and 488 test specimens obtained without the aid of a speculum, 18 and 62, respectively, displayed a diamine oxidase test result different from results of conventional tests (nitrazine paper, ferning, fetal cell stains). These discrepancies are discussed in view of the utility of the diamine oxidase test as an adjunct to conventional methods for diagnosing rupture of membranes. The diamine oxidase test appears to be objective, sensitive, quantitative, and capable of detecting amniotic fluid leaks more than 25 hours after rupture of membranes. It can be performed in 1 hour and requires a scintillation counter.