Design and construction of a 9 MeV γ-ray source based on capture of moderated plutonium-beryllium neutrons in nickel.

We have designed and constructed a high-energy γ-ray source for detector characterisation and calibration. The source is a composite type based on a plutonium-beryllium neutron emitter embedded in a paraffin moderator, which is homogeneously mixed with nickel powder. The 9 MeV γ-ray source produces approximately 450 photons per second in 4π when 2.2×105 neutrons per second are emitted, corresponding to a surface flux of 9 MeV γ-rays of approximately 2.5×10-6 cm-2 per emitted neutron. Here we discuss the properties and design of this source, including the characterisation of homogeneity and high-energy γ-ray emission spectra.

[Chorioretinal lesions in deaf mutes]. / Leziuni corioretiniene la surdomuti.

The paper reports a study of 216 patients of special deaf-mute schools from Craiova. The exam of them showed us the presence of retinal degenerative lesions in 17 cases (7.8%). There was not a parallelism between deafness' degree and retinal lesions expanse. In point of clinical aspect, the retinal degenerative lesions were Sjögreen retinal lesions in 6 cases, colloidal Amalric-Bessou retinal lesions in 6 cases. In 2 cases lesions had a pseudoinflammatory aspect and another 2 cases were peripheral lesions like "salt and pepper's". Only one case had pigmentary osteoblastic mobilization. Deafness was associated with oligophrenia in 15 cases, with discreet manifestations of eredoataxia Friedreich in 5 cases, with epilepsy in 2 cases and with nanism in another 2 cases. It is necessary a complex oto-neuro-ophthalmological exploration of patients with deaf-muteness.

[Parinaud's conjunctivitis]. / Conjunctivita Parinaud.

A case of a 31-years-old young with swollen left eyelid, abundant discharge and giant conjunctival follicles of all palpebral conjunctiva. The existence of the left unilateral preauricular and submaxillary adenopathy associated with anatomo-pathological exam of the conjunctival follicles decides the diagnosis of Parinaud conjunctivitis.

[Bilateral transverse optic neuropathy]. / Neuropatie optica transversa bilaterala.

It shows a clinical observation about optical anterior juxtabulbar bilateral neuropathy, with superacute debut, rapid and dramatic evolution in the first days, at a young woman. The disease established the marked diminuation of the visual acuity and the collapse of the visual field. The evolution was favourably under the cortisone therapy, establishing the total recovering of the visual function. Are discussed appearances about etiology and clinical specific features of optical juxtabulbar neuropathy, considering this isolated optical neuropathy like a first attack in evolution of one sclerosis in plaques.