Light Curve Analysis of Hipparcos Data for the Massive O-type Eclipsing Binary UW CMa

Hipparcos photometric data for the massive O-type binary UW CMa were analysed within the framework of the Roche model. Photometric solutions were obtained for five mass ratios in the $q=M_2/M_1=0.5-1.5$ range. The system is found to be in a contact configuration. Independently of $q$, the best-fitting model solutions correspond to the orbital inclination $i \sim 71^\circ$ and the temperature of the secondary component $T_2 \sim 33500\,K$, at the fixed temperature of the primary $T_1=33750 K$. Considering that the spectrum of the secondary is very weak, photometric solutions corresponding to the contact configuration favor the mass ratio $q$ smaller than unity (in which case the luminosity of the secondary is smaller than that of the primary). The absolute parameters of the system are estimated for different values of the mass ratio.Comment: 18 pages, 6 figure

Noise and disturbance caused by vehicles crossing cattle grids: comparison of installations

Cattle grids are used on roads and tracks to prevent grazing animals from leaving an open space without fencing onto a more controlled area where access to the road from surrounded land is more limited. They are widely used in the UK at the entrances to common and moorland areas where animals are free to roam, but also on private drive entrances. Typically, they consist of a series of metal bars across the road that are spaced so that an animal’s legs would fall through the gaps if it attempted to cross. Below the grid is a shallow pit that is intended to further deter livestock from using that particular crossing point. The sound produced as vehicles cross these devices is a characteristic low frequency “brrrr” where the dominant frequencies relates to the bar passage frequency under the tyres. The sound can be disturbing to riders and their horses and walkers and residents living close by as evidenced by press reports and the need to consider noise aspects in planning for new installations. For this reason and due to the lack of available information on the size and nature of the problem measurements and recordings have been made at a number of sites in Yorkshire in the UK. In addition, questionnaire surveys of residents living close by and façade measurements have also been used to gauge impact. Results show that there is a wide variation in the maximum noise level produced by cattle grids of apparently similar design. This can be related to impact noise produced by the movement of all or part of the grid as the frame comes under impulsive loading as the vehicle crosses. It was further established that some residents living close to the cattle grids were disturbed by the noise, and in some cases vibration, and wanted them removed or suitably modified

IPHAS and the symbiotic stars. I. Selection method and first discoveries

The study of symbiotic stars is essential to understand important aspects of stellar evolution in interacting binaries. Their observed population in the Galaxy is however poorly known, and is one to three orders of magnitudes smaller than the predicted population size. IPHAS, the INT Photometric Halpha survey of the Northern Galactic plane, gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume, and discover a significant number of new systems. A method of selecting candidate symbiotic stars by combining IPHAS and near-IR (2MASS) colours is presented. It allows us to distinguish symbiotic binaries from normal stars and most of the other types of Halpha emission line stars in the Galaxy. The only exception are T Tauri stars, which can however be recognized because of their concentration in star forming regions. Using these selection criteria, we discuss the classification of a list of 4338 IPHAS stars with Halpha in emission. 1500 to 2000 of them are likely to be Be stars. Among the remaining objects, 1183 fulfill our photometric constraints to be considered candidate symbiotic stars. The spectroscopic confirmation of three of these objects, which are the first new symbiotic stars discovered by IPHAS, proves the potential of the survey and selection method.Comment: Accepted for publication on Astronomy and Astrophysics. 12 pages, 8 figure

Structures for Environmental Action

This article develops a typology of what we term “structures for action”—strategies, mechanisms, and means—used by local environmental groups to facilitate actions such as lifestyle shifts, civic protest, and environmental preservation. Based on data from nineteen groups in several states, we distinguish between internal structures that facilitate action for members of the groups and external structures that facilitate action among nonmembers and other groups. Within both internal and external structures, we identify three dimensions: knowledge, meaning, and praxis. Our typology of structures for action is designed to stimulate further research and to be useful for environmental groups, as well as for other social issue-oriented local groups that seek to be more effective

Development and clinical acceptability of a pre-operative risk stratification tool of cerebellar mutism syndrome in children with posterior fossa tumour

Aims: Despite identification of numerous pre-operative cerebellar mutism syndrome (CMS) clinical and radiological predictors, a unifying pre-operative risk stratification model for use during surgical consent is currently lacking. The aims of the project are (1) to develop a simple, easy to implemented risk scoring scheme to flag patients at higher risk of post-operative CMS; and (2) to assess its clinical acceptability amongst medical professionals. Methods: The combined cohort consists of 89 patients from two major treatment centres (age: 2-23yrs, gender 28M,61F, MRI pathology estimate 36 medulloblastoma, 40 pilocytic astrocytoma, 12 ependymoma, 1 non-committal); 26 (29%) of whom developed post-operative CMS. Post-operative CMS status was ascertained from clinical notes and pre-operative MRI scans, blinded to CMS status, underwent structured evaluation for 21 tightly-defined candidate imaging risk markers based on prior literature. All variables were first screened based upon results from univariate analysis and C4.5 decision tree. Stepwise logistic regression was then used to develop the optimal model, and multiple logistic regression coefficients for the predictors were converted into risk scores. Results: Univariate analysis identified five significant risks and C4.5 decision tree identified six predictors. The final model (Table 1) has an accuracy of 88.8% (79/89), with a sensitivity of 96.2% (25/26) and specificity of 85.7% (54/63). Using risk score cut-offs 203 and 238 permit discrimination into low (38/89, predicted probability < 3%), intermediate (17/89, predicted probability 3–52%) and high-risk (34/89, predicted probability 52%), respectively (Figure 1). Three illustrative cases from these categories will be used to collect clinicians’ opinion on surgical treatment decision and the acceptability of using this risk stratification for decision making and surgical consenting process. A web-based voting app will be used. Conclusions: A risk stratification model for post-operative CMS could flag patients at increased risk pre-operatively and may influence strategies for surgical treatment of cerebellar tumours. Following future testing and prospective validation, this risk scoring scheme may be utilised during the surgical consenting process

Development and clinical acceptability of a pre-operative risk stratification tool of cerebellar mutism syndrome in children with posterior fossa tumour

Aims: Despite identification of numerous pre-operative cerebellar mutism syndrome (CMS) clinical and radiological predictors, a unifying pre-operative risk stratification model for use during surgical consent is currently lacking. The aims of the project are (1) to develop a simple, easy to implemented risk scoring scheme to flag patients at higher risk of post-operative CMS; and (2) to assess its clinical acceptability amongst medical professionals. Methods: The combined cohort consists of 89 patients from two major treatment centres (age: 2-23yrs, gender 28M,61F, MRI pathology estimate 36 medulloblastoma, 40 pilocytic astrocytoma, 12 ependymoma, 1 non-committal); 26 (29%) of whom developed post-operative CMS. Post-operative CMS status was ascertained from clinical notes and pre-operative MRI scans, blinded to CMS status, underwent structured evaluation for 21 tightly-defined candidate imaging risk markers based on prior literature. All variables were first screened based upon results from univariate analysis and C4.5 decision tree. Stepwise logistic regression was then used to develop the optimal model, and multiple logistic regression coefficients for the predictors were converted into risk scores. Results: Univariate analysis identified five significant risks and C4.5 decision tree identified six predictors. The final model (Table 1) has an accuracy of 88.8% (79/89), with a sensitivity of 96.2% (25/26) and specificity of 85.7% (54/63). Using risk score cut-offs 203 and 238 permit discrimination into low (38/89, predicted probability < 3%), intermediate (17/89, predicted probability 3–52%) and high-risk (34/89, predicted probability 52%), respectively (Figure 1). Three illustrative cases from these categories will be used to collect clinicians’ opinion on surgical treatment decision and the acceptability of using this risk stratification for decision making and surgical consenting process. A web-based voting app will be used. Conclusions: A risk stratification model for post-operative CMS could flag patients at increased risk pre-operatively and may influence strategies for surgical treatment of cerebellar tumours. Following future testing and prospective validation, this risk scoring scheme may be utilised during the surgical consenting process

Role of intermediary cells in Peltodon radicans (Lamiaceae) in the transfer of calcium and formation of calcium oxalate crystals

With the objective of studying the connection between calcium oxalate crystals formation and the phloem, fragments of leaves of Peltodon radicans Pohl (Lamiaceae) were fixed and processed, for light and electron-transmission microscopes. It was observed that the crystals occurred in the cells of the bundle sheath, juxtaposed in relation to the phloem. Intermediary cells established a connection between the sieve element and crystal-bearing sheath cells. Calcium was present abundantly in the cytoplasm of sheath cells as calcium oxalate crystals. The presence of calcium was also detected in the intermediary cells, but in the sieve elements it was not detected. There was, therefore, an increasing concentration gradient of calcium in the sieve elements from sheath cells. Thus, we hypothesized that the formation of calcium oxalate crystals regulates calcium levels in the sieve elements.Com o objetivo de estudar a relação entre cristais de oxalato de cálcio e floema, fragmentos de folhas de Peltodon radicans foram fixados e processados, segundo métodos usuais, para estudos ao microscópio de luz e eletrônico de transmissão. Observou-se que os cristais ocorrem nas células da bainha do feixe, lateralmente em relação ao floema. Células intermediárias estabelecem conexão entre elemento crivado e células da bainha, portadoras de cristais, com crescimento intrusivo entre estas. Íons cálcio são abundantes no citoplasma das células da bainha que contém cristais de oxalato de cálcio. Nas células intermediárias a detecção ultra-citoquímica de cálcio também apresentou resultados positivos, enquanto nos elementos crivados a presença deste íon não foi constatada. Há, portanto, um gradiente crescente de concentração de cálcio dos elementos crivados para as células da bainha. Assim, formulamos a hipótese de que a formação de cristais de oxalato de cálcio tem, em P. radicans, o objetivo de controlar os níveis de cálcio citossólico nos elementos crivados

Estruturas secretoras de mucilagem em Hibiscus pernambucensis Arruda (Malvaceae): distribuição, caracterização morfoanatômica e histoquímica

No presente trabalho foram estudadas as estruturas secretoras de mucilagem de Hibiscus pernambucensis aos microscópios de luz e de varredura. Conhecida como guaxima-do-mangue e algodão-do-brejo, é espécie nativa encontrada no litoral brasileiro, vegetando áreas de manguezal e restinga, tendo grande importância ecológica nestes ecossistemas. É importante produtora de fibras têxteis e celulose, fornece abundante mucilagem suscetível das mesmas aplicações medicinais de outras malváceas, além da presença de tanino. Coléteres, glândulas peroladas, tricomas secretores longo-pedunculados, canais, cavidades e idioblastos foram observados. Os coléteres ocorrem no ápice caulinar, estípulas, primórdios foliares, folhas, sépalas e pétalas jovens. As glândulas peroladas são encontradas nas superfícies adaxial e abaxial dos primórdios foliares. Os canais e as cavidades encontram-se distribuídos nos eixos vegetativo aéreo e reprodutivo. Os idioblastos ocorrem nas raízes, em estágios primários e secundários de desenvolvimento e no mesofilo foliar. A secreção presente nas diferentes estruturas secretoras é constituída predominantemente por polissacarídeos ácidos e neutros, podendo ocorrer proteínas, lipídeos e substâncias fenólicas. A presença de mucilagem, tanto na superfície como no interior dos órgãos, em diferentes fases do ciclo vegetativo e reprodutivo, representa um importante mecanismo adaptativo e de sobrevivência da espécie aos ambientes de restinga e mangue.This work studied the mucilage-secreting structures of Hibiscus pernambucensis using light and scanning electron microscopy. Known as guaxima-do-mangue, algodão-do-brejo and embira-do-mangue, this species is a native shrub that occurs in mangrove and restinga along the Brazilian coast, and is important in the production of textile fibers and cellulose, provides abundant mucilage that is used medicinally like other Malvaceae species, and has tannins. The results of this work found colleters, pearl glands, long-stalked secretory trichomes, ducts, cavities and idioblasts. The colleters occur on the shoot apices, stipules, leaf primordia, leaves, young sepals and petals. The pearl glands are present in the adaxial and abaxial surface of the leaf primordia. The ducts and the cavities occur in the vegetative and reproductive shoot apices. The idioblasts occur in the roots, both in primary and secondary stages of development, and in the leaf mesophyll. The secretion of the different secretory structures is made predominantly of acids and neutral polysaccharides, proteins, lipids and phenolic substances. The presence of external and internal mucilage-secreting structures in all plant organs, at different stages of development, represents an important adaptive mechanism to restinga and mangrove environments

Analysis of water ligands within the allosteric forms of phenylalanine hydroxylase

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Phenylalanine Hydroxylase (PheH) is a liver enzyme that catalyzes the conversion of L- phenylalnine to L-tyrosine using tetrahydrobiopterin and molecular oxygen. Deficiencies in this enzyme cause phenylketonuria (PKU), an autosomal recessive metabolic disorder that occurs in ~1/10,000 live births. The general mechanism of PheH consists of two major steps: (1) formation of the ferryl-oxo species and (2) hydroxylation of the aromatic amino acid L-phenylalanine. Before the coupled hydoxylation can occur, PheH is activated by the presence of L-phe from the T-(unactivated) to R-(activated)-state. Here activation is marked by a distinct increase in the specific activity, which corresponds to a 2.2 and 8-fold increase in the specific activity for hPheH and rPheH, respectively. Accompanying the activation of PheH is a global conformational change, which results in a ligand rearrangement of the active site. Mixed signals about the presence of water in the literature have lead to multiple accounts concerning the role water plays in the formation of the ferryl-oxo species.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;This work provided the basis for studying water ligands in pterin dependent non-heme iron enzymes with an [FeNO]7 spin system using 1H ESEEM and HYSCORE. Based on qualitative argument with the 1H ESEEM spectra from the [FeNO]7-(N2O)(H2O)2 and [FeNO]7-(N2O2)(H2O)1 model complexes, it was determined that the activation of PheH, without BH4 complexed, lead to a one water dehydration of PheH's active site. The water ligands were then quantitatively analyzed to show characteristic dipolar distances (from the iron to the water protons) of 2.52 - 2.62 \uc5 and &#946; angles between 58\ub0 - 83\ub0 and 97\ub0 - 122\ub0. The observed dipolar distances and angles are consitent with water ligands that are located cis to the binding site of NO. Overall, this analysis demonstrated the ability of using 1H ESEEM and HYSCORE to study water ligands bound to non-heme iron enzymes.Thesis (Ph. D.)--Michigan State University. Chemistry, 2013Includes bibliographical references (pages 180-183