Mammal-Like Organization of the Avian Midbrain Central Gray and a Reappraisal of the Intercollicular Nucleus

In mammals, rostrocaudal columns of the midbrain periaqueductal gray (PAG) regulate diverse behavioral and physiological functions, including sexual and fight-or-flight behavior, but homologous columns have not been identified in non-mammalian species. In contrast to mammals, in which the PAG lies ventral to the superior colliculus and surrounds the cerebral aqueduct, birds exhibit a hypertrophied tectum that is displaced laterally, and thus the midbrain central gray (CG) extends mediolaterally rather than dorsoventrally as in mammals. We therefore hypothesized that the avian CG is organized much like a folded open PAG. To address this hypothesis, we conducted immunohistochemical comparisons of the midbrains of mice and finches, as well as Fos studies of aggressive dominance, subordinance, non-social defense and sexual behavior in territorial and gregarious finch species. We obtained excellent support for our predictions based on the folded open model of the PAG and further showed that birds possess functional and anatomical zones that form longitudinal columns similar to those in mammals. However, distinguishing characteristics of the dorsal/dorsolateral PAG, such as a dense peptidergic innervation, a longitudinal column of neuronal nitric oxide synthase neurons, and aggression-induced Fos responses, do not lie within the classical avian CG, but in the laterally adjacent intercollicular nucleus (ICo), suggesting that much of the ICo is homologous to the dorsal PAG

Characterisation of a single photon counting pixel detector

The Large Area Detector is a photon counting detector based on pixel readout ASICs with 64×64 arrays of square pixels bump bonded to a thick Si detector. It is designed for X-ray diffraction studies and is capable of up to count rate per pixel. A prototype has been tested at the synchrotron radiation source in Daresbury in a X-ray beam. This paper focuses on the spatial resolution and noise performance. The calculation of modulation transfer functions leads to analytical formulae allowing the determination of the theoretical spatial resolution

Charge sharing in silicon pixel detectors

We used a pixellated hybrid silicon X-ray detector to study the effect of the sharing of generated charge between neighbouring pixels over a range of incident X-ray energies, 13–36 keV. The system is a room temperature, energy resolving detector with a Gaussian FWHM of 265 eV at 5.9 keV. Each pixel is 300 μm square, 300 μm deep and is bump bonded to matching read out electronics. The modelling packages MEDICI and MCNP were used to model the complete X-ray interaction and the subsequent charge transport. Using this software a model is developed which reproduces well the experimental results. The simulations are then altered to explore smaller pixel sizes and different X-ray energies. Charge sharing was observed experimentally to be 2% at 13 keV rising to 4.5% at 36 keV, for an energy threshold of 4 keV. The models predict that up to 50% of charge may be lost to the neighbouring pixels, for an X-ray energy of 36 keV, when the pixel size is reduced to 55 μm

Performance of an energy resolving X-ray pixel detector

We have built a back-illuminated, silicon X-ray detector with 16×16 pixels. This is bump-bonded to an integrated circuit containing a corresponding array of pre-amplifiers. The bump-bonded unit is wire bonded to two 128 channel integrated circuits which have signal shaping, peak-hold and sparcification logic. These integrated circuits output the analogue value of the individual X-ray and the address of the 300 μm×300 μm pixel. The system has previously demonstrated X-ray spectroscopy measurement in the 5–40 keV range with a resolution of 1 keV FWHM. This paper describes the performance of the system used in an X-ray diffraction experiment performed on the Daresbury Synchrotron Radiation Source. The second part demonstrates the successful operation of this pixellated detector for spectroscopy. In this part, the variation among the pixel outputs is accounted for without significantly affecting the noise performance

Avaliação pré-operatória visando ao uso do halo craniano no tratamento de deformidades rígidas da coluna vertebral Evaluación pre-operatoria del uso del halo craneal en lo tratamiento de las deformidades rígidas de la columna vertebral Preoperative evaluation for the use of cranial halo traction in the spine treatment of rigid deformities

OBJETIVO: avaliar a eficácia e a segurança do uso do halo craniano gravitacional como técnica de tratamento de deformidades rígidas da coluna vertebral e rever complicações associadas ao seu tratamento. MÉTODOS: análise retrospectiva de dez pacientes com deformidades rígidas da coluna vertebral: cifose, escoliose, cifoescoliose e hiperlordose cervical. O critério para inclusão dos pacientes foi o uso do halo craniano gravitacional em um período pré-operatório e interoperatório em deformidades rígidas da coluna vertebral. Foram avaliados os prontuários dos pacientes e suas mensurações radiográficas foram feitas em um período pré-operatório, após instalação do halo craniano gravitacional, e no período pós-operatório. As variáveis estudadas foram idade, sexo, valor angular da curva principal, valor angular da curva secundária, valor angular da curva sagital maior, protocolo de tração e tipo de procedimento utilizado. RESULTADOS: em relação ao plano frontal, avaliou-se, no período pré-operatório, a média angular de 89,9º, decrescendo para 65º após a instalação do halo e 56,9º no pós-operatório. Analisando o plano sagital, observou-se no período pré-operatório o valor angular de 77,7º, decrescendo para 55,4º, com o uso do halo-colete, e 46,5º no pós-operatório tardio. CONCLUSÃO: pode-se concluir que o uso da tração halo craniana é um método eficaz no auxílio da correção das deformidades rígidas da coluna vertebral, visto que se conseguiu uma correção significativa das deformidades do período pré-operatório para os períodos pós-instalação do halo e pós-operatório, sem se observar lesão neurológica ou outra grave complicação.<br>OBJETIVO: evaluar, retrospectivamente, la eficacia y la seguridad del uso del halo craneal gravitacional como técnica de tratamiento de deformidades rígidas de la columna vertebral, y rever complicaciones asociadas a su tratamiento. MÉTODOS: ha sido analizado un total de diez pacientes con deformidades rígidas de la columna vertebral: cifosis, escoliosis, cifoscoliosis e hiperlordosis cervical. El criterio para inclusión de los pacientes fue el uso del halo craneal gravitacional en un periodo preoperatorio y interoperatorio en deformidades rígidas de la columna vertebral. Han sido evaluados los prontuarios de los pacientes y sus mediciones radiográficas en un periodo preoperatorio, tras la instalación del halo craneal gravitacional y en el periodo postoperatorio. Las variables estudiadas fueron: edad, sexo, valor angular de la curva principal, valor angular de la curva secundaria, valor angular de la curva sagital mayor, protocolo de tracción y tipo de procedimiento utilizado. RESULTADOS: en relación al plano frontal, se ha evaluado, en el periodo preoperatorio, la media angular de 89,9º, decreciendo para 65,0º tras la instalación del halo y 56,9º en el postoperatorio. Analizando el plano sagital, se observa en el periodo preoperatorio el valor angular de 77,7º, decreciendo para 55,4º con el uso del halo y 46,5º en el postoperatorio. CONCLUSIÓN: se puede concluir que el uso de la tracción de halo craneal es un método eficaz para ayudar a corregir las deformidades de la columna rígida, ya que se logró una significativa corrección de las deformidades antes de la operación por los períodos después de la instalación de halo y postoperatorio, sin previo aviso u otras complicaciones neurológicas graves.<br>OBJECTIVE: to assess the efficacy and safety of using the gravitational cranial halo as a technique for treating rigid deformities in the spinal column and to revisit complications associated to the treatment. METHODS: a total of ten patients with rigid spinal deformities were studied, with the following deformities: kyphosis, scoliosis, kyphoscoliosis and cervical hyperlordosis. The criterion for including a patient was the use of the gravitational cranial halo in a postoperative period and interoperative period for rigid spinal deformities. The patient medical records and their radiographic measurements were studied and compared in a preoperative period, after the installation of the gravitational cranial halo and in the postoperative period. The aspects analyzed were: age, sex, angular value of the main curvature and angular value of the secondary curvature, angular value of the major sagittal curvature, traction protocol and type of procedure. RESULTS: in the frontal plane, an average angle of 89.9º was found in the preoperative period, decreasing to 65º after the installation of the halo and 56.9º in the postoperative period. In the sagittal plane, an angular value of 77.7º was observed, decreasing to 55.4º with the use of the halo and 46.5º in the postoperative period. CONCLUSION: the conclusion was that the use of cranial halo traction is an efficient method for correcting rigid spinal deformities, taking into account that there was significant correction of the deformities from the preoperative period to the post installation of the halo and the postoperative period, without any neurological lesions or serious complications resulting from the treatment