6,058 research outputs found
Hunting for asymptotia at LHC
We discuss whether the behaviour of some hadronic quantities, such as the
total cross-section, the ratio of the elastic to the total cross-section, are
presently exhibiting the asymptotic behaviour expected at very large energies.
We find phenomenological evidence that at LHC7 there is still space for further
evolution.Comment: 5 pages, 2 figures, talk given by G. Pancheri at International
Workshop on Diffraction in High-Energy Physics, DIFFRACTION 2012, Puerto del
Carmen, Canary Islands, Spain. To appear in AIP Conf. Pro
Serial stereotactic biopsy of brainstem lesions in adults improves diagnostic accuracy compared with MRI only.
Objective: The aim of the current prospective study was
to analyse the validity of MRI based diagnosis of
brainstem gliomas which was verified by stereotactic
biopsy and follow-up evaluation as well as to assess
prognostic factors and risk profile.
Methods: Between 1998 and 2007, all consecutive adult
patients with radiologically suspected brainstem glioma
were included. The MRI based diagnosis of the lesions
was made independently by an experienced neuroradiologist.
Histopathological evaluation was performed in all
patients from paraffin embedded specimens obtained by
multimodal image guided stereotactic serial biopsy
technique. Histopathological results were compared with
prior radiological assessment. Length of survival was
estimated with the Kaplan–Meier method and prognostic
factors were calculated using the Cox model.
Results: 46 adult patients were included. Histological
evaluation revealed pilocytic astrocytoma (n=2), WHO
grade II glioma (n=14), malignant glioma (n=12),
metastasis (n=7), lymphoma (n=5), cavernoma
(n=1), inflammatory disease (n=2) or no tumour/
gliosis (n=3). Perioperative morbidity was 2.5% (n=1).
There was no permanent morbidity and no mortality. All
patients with ‘‘no tumour’’ or ‘‘inflammatory disease’’
survived. Patients with low grade glioma and malignant
glioma showed a 1 year survival rate of 75% and 25%,
respectively; the 1 year survival rate for patients with
lymphoma or metastasis was 30%. In the subgroup with a
verified brainstem glioma, negative predictors for length of
survival were higher tumour grade (p=0.002) and
Karnofsky performance score (70 (p=0.004).
Conclusion: Intra-axial brainstem lesions with a radiological
pattern of glioma represent a very heterogeneous
tumour group with completely different outcomes.
Radiological features alone are not reliable for diagnostic
classification. Stereotactic biopsy is a safe method to
obtain a valid tissue diagnosis, which is indispensible for
treatment decision
Flujo alrededor de un cilindro: efecto de la condición de contorno en la pared y de la anchura del dominio
En el presente trabajo se examina la influencia de la localización de los lÃmites laterales del dominio computacional en el cálculo de los principales parámetros de un flujo bidimensional oscilatorio incompresible alrededor de un cilindro. Los experimentos numéricos se han realizado
a un Pr = 0,7 y dentro de un intervalo de números de Reynolds que va desde 60 a 200. Se
han utilizado, en todos los casos, mallas ortogonales no uniformes cuyos puntos de cálculo vienen dados por la intersección entre las isolÃneas de función de corriente y las de potencial de velocidad de un flujo potencial alrededor de un cilindro. Los resultados obtenidos en este trabajo son comparados con datos experimentales y numéricos.The influence of the location of the lateral computational boundaries on the main
parameters of two-dimensional unsteady incompressible flow past a circular cylinder is investigated in the present work. The numerical experiments are realized over 60 < Re < 200 and Pr = 0,7. We use, in al1 cases, non uniform orthogonal grids. Their nodes are tlle intersection between the streamlines and the velocity potencial isolines of a potencial flow around a cylinder. The results obtained in this work are compared with experimental arid numerical data.Peer Reviewe
Band gap control via tuning of inversion degree in CdInS spinel
Based on theoretical arguments we propose a possible route for controlling
the band-gap in the promising photovoltaic material CdInS. Our
\textit{ab initio} calculations show that the experimental degree of inversion
in this spinel (fraction of tetrahedral sites occupied by In) corresponds
approximately to the equilibrium value given by the minimum of the theoretical
inversion free energy at a typical synthesis temperature. Modification of this
temperature, or of the cooling rate after synthesis, is then expected to change
the inversion degree, which in turn sensitively tunes the electronic band-gap
of the solid, as shown here by accurate screened hybrid functional
calculations.Comment: In press in Applied Physics Letters (2012); 4 pages, 2 figures, 1
tabl
Effect of Polyethylene Glycol Treatment on Acetic Acid Emissions from Wood
Acetic acid is known to be emitted from sound wood and can accelerate damage to heritage materials, particularly metals. However, few studies have investigated the extent of acetic acid emissions from archaeological wood. This research utilised Solid-Phase-Micro-Extraction (SPME) GC–MS and lead coupon corrosion to identify volatile emissions from polyethylene glycol (PEG)-treated archaeological wood from the Mary Rose collection and assess if they could cause accelerated damage. In addition, the effect of PEG treatment on acetic acid emissions was investigated using sound wood samples. For sound wood, the PEG treatment acted as a barrier to acetic acid emissions, with higher-molecular-weight PEGs preventing more emissions. Archaeological wood, despite its age and high-molecular-weight PEG treatment, still emitted detectable concentrations of acetic acid. Moreover, they emitted a wider array of compounds compared to sound wood, including carbon disulphide. Like sound wood, when the archaeological wood samples were in a sealed environment with lead coupons, they caused accelerated corrosion to lead. This evidences that archaeological wood can emit high enough concentrations of volatile compounds to cause damage and further investigation should be performed to evaluate if this can occur inside museum display cases
Benign Bilateral Adenomyoepithelioma of the Mammary Gland in a Ring-tailed Lemur (Lemur catta)
Naturally occurring mammary tumours are uncommon in prosimians. A 20-year-old female ring-tailed lemur (Lemur catta) developed bilateral enlargement of the mammary glands. Surgical removal revealed that both masses were comprised of multiple nodules and cystic areas that entirely replaced the normal glands. Histologically, a benign neoplastic biphasic cellular proliferation, composed of luminal–epithelial and basal–myoepithelial components, was identified. Immunohistochemical analysis for expression of cytokeratin (CK) AE1/AE3, CK7, CK5 + 8, CK14, vimentin, p63 and 14-3-3σ highlighted the biphasic nature of the neoplasm. A low mitotic count, low Ki67 labelling index, expression of oestrogen receptor-α, lack of expression of human epidermal growth factor receptor and a 3-year disease-free period without recurrence supported the benign nature of the tumour. Macroscopically, histologically and immunohistochemically this neoplasm resembled benign adenomyoepithelioma of the breast in women. This is the first complete report of a naturally occurring mammary tumour in a ring-tailed lemur
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