A potential new method for determining the temperature of cool stars

‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.13489.xPeer reviewe

Square spirals, dimensionality and biopolymers

AbstractThis paper illustrates the diversity and esthetic beauty of the spatial patterns produced by a class of heuristic procedures describable by a one-parameter algorithm. While the patterns may provide insight into the structures of biopolymers and other macromolecules, the main focus of this work is the demonstration of how two-dimensional order may arise from one-dimensional processes

Galois theory and Lubin-Tate cochains on classifying spaces

We consider brave new cochain extensions F(BG +,R) → F(EG +,R), where R is either a Lubin-Tate spectrum E n or the related 2-periodic Morava K-theory K n , and G is a finite group. When R is an Eilenberg-Mac Lane spectrum, in some good cases such an extension is a G-Galois extension in the sense of John Rognes, but not always faithful. We prove that for E n and K n these extensions are always faithful in the K n local category. However, for a cyclic p-group C p r, the cochain extension F(BC p r +,E n ) → F(EC p r +, E n ) is not a Galois extension because it ramifies. As a consequence, it follows that the E n -theory Eilenberg-Moore spectral sequence for G and BG does not always converge to its expected target

The collapse of Io's primary atmosphere in Jupiter eclipse

Volcanic outgassing due to tidal heating is the ultimate source of a tenuous SO atmosphere around Jupiter's moon Io. The question of whether SO frost on the surface plays a part, and to what degree, in maintaining Io's atmosphere with the constant volcanic outgassing is still debated. It is believed that for a sublimation-supported atmosphere, the primary atmosphere should collapse during eclipses by Jupiter, as the SO vapor pressure is strongly coupled to the temperature of the ice on the surface. No direct observations of Io's atmosphere in eclipse have previously been possible, due to the simultaneous need for high spectral and time sensitivity, as well as a high signal-to-noise ratio. Here we present the first ever high-resolution spectra at 19 µm of Io's SO atmosphere in Jupiter eclipse from the Gemini telescope. The strongest atmospheric band depth is seen to dramatically decay from 2.5 ± (0.08)% before the eclipse to 0.18 ± (0.16)% after 40 min in eclipse. Further modeling indicates that the atmosphere has collapsed shortly after eclipse ingress, implying that the atmosphere of Io has a strong sublimation-controlled component. The atmospheric column density—from pre-eclipse to in-eclipse—drops by a factor of 5 ± 2.C.C.C.T. and J.R.S. at Southwest Research Institute were funded by NASA Outer Planets Research grant NNX14AC63G and Planetary Astronomy grant NNX11AD61G. M.A.L.V. was funded by the Spanish Ministerio de Economia y Competitividad and by FEDER funds under project ESP2015-65064-C2-1-P (MINECO/FEDER)Peer Reviewe

Flexible Power Modeling of LTE Base Stations

With the explosion of wireless communications in number of users and data rates, the reduction of network power consumption becomes more and more critical. This is especially true for base stations which represent a dominant share of the total power in cellular networks. In order to study power reduction techniques, a convenient power model is required, providing estimates of the power consumption in different scenarios. This paper proposes such a model, accurate but simple to use. It evaluates the base station power consumption for different types of cells supporting the 3GPP LTE standard. It is flexible enough to enable comparisons between state-of-the-art and advanced configurations, and an easy adaptation to various scenarios. The model is based on a combination of base station components and sub-components as well as power scaling rules as functions of the main system parameters

Valor clínico de la tomografía de emisión de positrones con F-18-FDG en el seguimiento de pacientes con cáncer de ovario

Background. Positron emission tomography with fluor- 18-deoxyglucose (PET-FDG) is an efficient technique for the detection of tumoural tissue. The aim of the paper is to evaluate the PET-FDG in the diagnosis of residual disease or relapse in patients with cancer of the ovary. Methods. A total of 24 patients, diagnosed and treated for cancer of the ovary with surgery and subsequent chemotherapy, were included. With 12 patients the study was carried out prior to second-look surgery, and with the other 12 after objectivising an increase of the tumoural marker in the follow up. Abdominal-pelvic CAT, determination of the seric levels of CA-125 and PET-FDG of thorax, abdomen and pelvis were carried out on all patients. The PET-FDG was evaluated in a qualitative way through the visual study of the images, and quantitatively through the SUV or standard uptake value. The definitive diagnosis was confirmed through an anatomopathological study in 13 cases and through clinical follow up in the rest with an average of 11.2±5.4 months (range 6-24). Results. A CA-125 value higher than 35 UI/ml was considered positive, obtaining a sensitivity of 77% and a specificity of 100%. The sensitivity of the CAT was 23% and the specificity 91%. With the FDG-PET sensitivity was 92% and the specificity 90%. A SUV value ≥ 3 was considered pathological, obtaining the same results as with the visual evaluation. The FDG-PET was positive in 5 patients with non-conclusive CAT, 4 with negative CAT and 2 with negative CA-125. Conclusion. These preliminary results suggest that the FDG-PET could be useful in the follow up of patients treated for cancer of the ovary. The FDG-PET could be efficient in the differentiation between residual disease or recurrence, as opposed to sequels to the treatment, when the CAT is not conclusive due to anatomical distortion. The FDG-PET could be more sensitive than an increased marker value, and facing an increase of the latter it permits a non-invasive localisation of the disease

Diagnostic value of quantitative SPECT/CT in assessing active sacroiliitis in patients with axial spondylarthritis and/or inflammatory low back pain

Background. The diagnostic accuracy of bone scintigraphy (BS) increases with SPECT/CT imaging. It would therefore be appropriate to reassess the diagnostic utility of scintigraphy in sacroiliitis with axial spondyloarthritis (SpA). The aim of this study was to compare the diagnostic performance of MRI, SPECT/CT and a combination of both techniques in sacroiliitis, and to evaluate the correlation between quantitative SPECT/CT indices and quantitative MRI inflammatory lesion scores. Methods. Thirty-one patients with active SpA and 22 patients with inflammatory low back pain underwent MRI and SPECT/CT of the sacroiliac joints. The diagnostic accuracy of both techniques was calculated using clinical diagnosis as the gold standard. The correlation between MRI and SPECT/CT was calculated by comparing the SPECT/CT activity indices and the Berlin/SPARCC scoring systems for MRI. Results. The sensitivity and specificity values in quantitative SPECT/CT, taking the sacroiliac/promontory ratio of >1.36 as the cut-off value, were close to those from MRI published in the literature. The combination of both techniques increased sensitivity while maintaining high specificity. There was a moderate correlation between SPECT/CT and MRI total scores. This correlation was improved by using solely the MRI inflammation scores. Conclusion. Quantitative SPECT/CT showed better diagnostic accuracy than planar scintigraphy and showed a moderate correlation with MRI scores in active sacroiliitis. The combination of both tests increased the diagnostic accuracy. Quantitative SPECT/CT could play a relevant role in the diagnosis of active sacroiliitis in patients with high a suspicion of SpA and a negative/inconclusive MRI test or in patients with whom MRI studies cannot be carried out.Fundamento. La precisión diagnóstica de la gammagrafía ósea (GO) aumenta con las imágenes SPECT/TAC haciendo conveniente reevaluar su utilidad diagnóstica en la sacroilitis de la espondiloartritis axial (EA). El objetivo fue comparar el rendimiento diagnóstico de la resonancia magnética (RM), la SPECT/TC y ambas pruebas combinadas, y evaluar la correlación entre los índices cuantitativos de ambas técnicas. Métodos. A 31 pacientes con EA activa y 22 con lumbalgia inflamatoria se les realizó una RM y una SPECT/TC de las articulaciones sacroilíacas y se calculó la precisión diagnóstica de ambas técnicas respecto al diagnóstico clínico. La correlación entre ambas pruebas se calculó comparando los índices de actividad del SPECT/TC con los sistemas de puntuación Berlín y SPARCC de RM. Resultados. Los valores de sensibilidad y especificidad de la SPECT/TC cuantitativa, tomando como punto de corte el cociente sacroilíaca/promontorio >1,36, fueron similares a los publicados para la RM. La combinación de ambas técnicas aumentó la sensibilidad manteniendo una alta especificidad. La correlación entre las escalas totales de RM y SPECT/TC fue moderada y mejoraba al utilizar únicamente las escalas de inflamación. Conclusiones. La SPECT/TC cuantitativa muestra una mejor precisión diagnóstica que la GO planar en la sacroilitis activa y una correlación moderada con las puntuaciones de RM. La combinación de ambas técnicas aumenta la precisión diagnóstica. Por tanto, la SPECT/TAC cuantitativa podría tener un papel relevante en el diagnóstico de sacroilitis en pacientes con alta sospecha de EA y RM negativa/no concluyente o en aquellos pacientes en los que no se pueda realizar una RM

Thermal radiation processes

We discuss the different physical processes that are important to understand the thermal X-ray emission and absorption spectra of the diffuse gas in clusters of galaxies and the warm-hot intergalactic medium. The ionisation balance, line and continuum emission and absorption properties are reviewed and several practical examples are given that illustrate the most important diagnostic features in the X-ray spectra.Comment: 37 pages, 16 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 9; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

Tomografía de emisión de fotones cerebral. Valor del índice corticocerebeloso y patrones gammagráficos en la enfermedad de Alzheimer y otras afecciones

Brain single photon emission computed tomography (SPECT) with 99mTc-HMPAO is a diagnostic tool for evaluating regional cerebral blood flow. Recently, the diagnostic possibilities of the method are being investigated in some neurologic disorders, such as cerebrovascular accidents, seizures and dementia. This work has been carried out with 54 subjects, 9 healthy volunteers and 45 patients (31 dementia and 14 epileptics), in order to evaluate gammagraphic patterns and the utility of cortico/cerebellar activity indexes. An interesting diagnostic finding is a significant decrease (p less than 0.001) in perfusion of temporoparietal regions in the patients with Alzheimer's disease in relation with the healthy volunteers' group. We have not found significant changes in perfusion in the group of epileptic patients during the interictal phase. We conclude emphasizing the interest of the SPECT in the differential diagnosis of dementia