3,386 research outputs found
Swift/XRT monitoring of five orbital cycles of LS I+61° 303
No full textContext.LS I +61° 303 is one of the most interesting high-mass X-ray binaries owing to its spatially resolved radio emission and its TeV emission, generally attributed to non-thermal particles in an accretion-powered relativistic jet or in the termination shock of the relativistic wind of a young pulsar. Also, the nature of the compact object is still debated. Only LS 5039 and PSR B1259-63 (which hosts a non-accreting millisecond pulsar) have similar characteristics.
Aims.We study the X-ray emission from LS I +61° 303 covering both short-term and orbital variability. We also investigate the source spectral properties in the soft X-ray (0.3–10 keV) energy range.
Methods.Twenty-five snapshot observations of LS I +61° 303 were collected in 2006 with the XRT instrument on-board the Swift satellite over a period of four months, corresponding to about five orbital cycles. Since individual data sets have too few counts for a meaningful spectral analysis, we extracted a cumulative spectrum.
Results.The count rate folded at the orbital phase shows a clear modulation pattern at the 26.5 days period and suggests that the X-ray peak occurs around phase 0.65. Moreover, the X-ray emission appears to be variable on a timescale of ~1 ks. The cumulative spectrum is well described by an absorbed power-law model, with hydrogen column density cm-2 and photon index . No accretion disk signatures, such as an iron line, are found in the spectrum
Production of lipospheres for bioactive compounds delivery
No full textLipospheres (LS), have been proposed as new type of fat-based matrix developed for drug delivery of bioactive compounds. LS combine the advantages of polymeric nanoparticles, fat emulsions and liposomes avoiding some of their disadvantages, such as cytotoxic effects after phagocytosis, toxic effects of organic residues after the production of polymers, lack of large industrial scale production. Due to their large particle size range (comprised between 0.2-500 μm), LS can be administered by different routes, such as oral, subcutaneous, intramuscular, topic or used for cells encapsulation. The targeting to phagocytic cells could be approached by LS for the treatment of many infectious deseases (i.e. AIDS) and for the administration of hormones, such as growth factors. In addition, the encapsulation of some antibiotics, such as tetracycline, for the treatment of periodontal diseases and enteric infections could be facilitated. The in vivo distribution of LS demonstrated an high affinity to vascular wells (including capillaries), to inflamed tissues and to granulocytes.
This study evaluate (a) the production of LS obtained by emulsion-melt dispersion and by solvent evaporation, (b) the influence of preparation parameters on liposphere morphology and (c) the microparticles' release of model drugs (retinyl acetate, progesteron and sodium cromoglycate). To obtain a biocompatible formulation for humans, triglycerides and monoglycerides were chosen as biomaterials, due to their high biocompatibility and high physicochemical stability.
Our results demonstrated that the morphological characteristics of the produced LS are influenced by (a) the type of lipid matrix used, (b) stabilizer, (c) the stirring speed and (d) type of paddle strirrer. Nevertheless, LS can entrap efficiently both hydrophobic and hydrophilic drugs and control the release of the encapsulated drug. In addition, the activity of the drug towards the target is increased and the cytotoxic systemic effects minimalized. The encouraging results obtained in this study could propose LS for future clinical trials, especially in the vehiculation of anti-infectives and hormones
FIGURES 15–16 in Panava a senior synonym of Wulpisca, and description of new species of Panava and Dexosarcophaga (Bezzisca) from the Brazilian Amazon (Diptera, Sarcophagidae)
No full textFIGURES 15–16. Dexosarcophaga tracua sp. nov., male terminalia. 15. Distiphallus, ventral view. 16. Distiphallus, ventral view. Scale bar = 0.1 mm. Abbreviations: ju = juxta, ls = lateral stylus, ms = median stylus, ve = vesica.Published as part of Filho, Fernando Da Silva Carvalho & Esposito, Maria Cristina, 2011, Panava a senior synonym of Wulpisca, and description of new species of Panava and Dexosarcophaga (Bezzisca) from the Brazilian Amazon (Diptera, Sarcophagidae), pp. 49-56 in Zootaxa 2808 on page 55, DOI: 10.5281/zenodo.20215
Author Attributions in Medieval Text Collections: An Exploration
No full textThis article examines the role and function of author attributions in multi-text manuscripts containing Dutch, English, French or German short verse narratives. The findings represent one strand of the investigations undertaken by the cross-European project ‘The Dynamics of the Medieval Manuscript’, which analysed the dissemination of short verse narratives and the principles of organisation underlying the compilation of text collections. Whilst short verse narratives are more commonly disseminated anonymously, there are manuscripts in which authorship is repeatedly attributed to a text or corpus. Through six case studies, this article explores medieval concepts of authorship and how they relate to constructions of authority, whether regarding an empirical figure or a literary construction. In addition, it looks at how authorship plays a role in manuscript compilation, and at the effects of attributions (by author and/or compiler) on reception. The case studies include manuscripts from the thirteenth to fifteenth centuries, produced in a range of social and cultural contexts, and featuring some of the most important European authors of short verse narratives: Rutebeuf, Baudouin de Condé, Der Striker, Konrad von Würzberg, Willem of Hildegaersberch, and Geoffrey Chaucer. The preliminary findings contribute to our understanding of author attributions in text collections from across northern Europe and point towards future lines of enquiry into the role of authorship in medieval textual dissemination
Batch Bayesian Learning of Large-Scale LS-SVMs Based on Low-rank Tensor Networks
No full textLeast Squares Support Vector Machines (LS-SVMs) are state-of-the-art learning algorithms that have been widely used for pattern recognition. The solution for an LS-SVM is found by solving a system of linear equations, which involves the computational complexity of O(N^3). When datasets get larger, solving LS-SVM problems with standard methods becomes burdensome or even unfeasible. The Tensor Train (TT) decomposition provides an approach to representing data in highly compressed formats without loss of accuracy. By converting vectors and matrices in the TT format, the storage and computational requirements can be greatly reduced. In this thesis, we develop a Bayesian learning method in the TT format to solve large-scale LS-SVM problems, which involves the computation of a matrix inverse. This method allows us to include the information we know about the model parameters in the prior distribution. As a result, we are able to obtain a probability distribution of the parameters, which enables us to construct confidence levels of the predictions. In the numerical experiment, we show that the developed method performs competitively with the current methods.Mechanical Engineering | Systems and Contro
Experience with laparoscopic splenectomy
No full textBackground/Purpose: The laparoscopic splenectomy (LS) often
is adopted to treat children affected by hematologic
diseases. Many of the pitfalls of LS are related to the 2
steps—dissection and extraction. Although various methods
have been adopted, the conversion rate still is too high
during the learning curve period. The authors analyse their
experience in 54 laparoscopic splenectomies performed by
their teams in 3 European countries.
Methods: From 1995 to 1999, 54 children underwent laparoscopic
splenectomy, 4 of whom also underwent a concomitant
cholecystectomy. There were 29 girls and 25 boys with
ages ranging between 4 and 19 years (median, 8.1 years). All
patients underwent an elective laparoscopic splenectomy:
Thirty children had hereditary spherocytosis, 13 had an idiopathic
thrombocytopenic purpura, 10 were affected by a b
thalassemia, and 1 child had sickle cell disease.
Results: Mean operating time was 140 minutes (range, 100 to
250 minutes). Hospital stay ranged from 2 to 6 days (median,
3 days). In 7 patients the spleen was removed through a 7-cm
minilaparotomy; in another 46 cases the spleen was captured
into an extraction bag, fragmented, and then removed
through the umbilical or left orifice. There was one conversion
to open surgery because of a camera failure during the
operation.
Conclusions: On the basis of our experience we believe that
the operating time of LS is still too long compared with open
surgery, and the extraction phase still not simple enough. A
perfect control of hemostasis is fundamental because severe
complications can arise from even a slight bleeding episode.
It also is very important to search for and remove any
accessory spleens. In our series this occurred in 7 patients,
one of whom had 3 accessory spleens. The laparoscopic
approach is today a good alternative to open splenectomy
Additive Manufacturing: Polymers Applicable for Laser Sintering (LS)
No full textAbstractAdditive Manufacturing (AM) is close to become a production technique changing the way of part fabrication in future. Enhanced complexity and personalized features are aimed. The expectations in AM for the future are enormous and betimes it is considered as kind of the next industrial revolution. Laser Sintering (LS) of polymer powders is one component of the AM production techniques. However materials successfully applicable to Laser Sintering (LS) are very limited today. The presentation picks up this topic and gives a short introduction on the material available today. Important factors of polymer powders, their significance for effective LS processing and analytical approaches to access those values are presented in the main part. Concurrently the exceptional position of polyamide 12 powders is this connection is outlined
Pediatric laparoscopic splenectomy: are there real advantages in comparison with traditional open approach?
No full textThe hospital records of patients who underwent splenectomy during the last 2 years were reviewed to compare the advantages of the laparoscopic approach with traditional open splenectomy (OS). Between March 1994 and March 1996, 16 children underwent splenectomy, in 8 using an open approach and 8 by a laparoscopic procedure. Of the patients who underwent laparoscopic splenectomy (LS), 2 had a concomitant cholecystectomy. Ages ranged between 4 and 11 years (mean 6.4 years); there were 9 girls and 7 boys. The indications for splenectomy were: hereditary spherocytosis (7 cases); idiopathic thrombocytopenic purpura (4); sickle-cell disease (3); and beta-thalassemia (2). The average operating time for OS was 100 min (range, 50-155), for LS 170 min (range 125-240). The hospital stay for patients who had OS ranged from 3 to 9 days (mean 4.7), for those who had LS from 2 to 5 days (mean 3). One OS patient developed a wound infection. In 3 of the LS patients, the spleen was removed via a 7-cm Pfannenstiel minilaparotomy in the suprapubic region; in 5 cases the spleen was captured into an extraction bag, crushed, and removed through the umbilical orifice. The authors believe that LS must be performed only when it is possible to use the extraction bag to remove the spleen from the umbilical orifice (spleens weighing less than 700 g) and when a concomitant procedure such as cholecystectomy is indicated; in other cases OS is preferable
Production of lipospheres as carriers for bioactive compounds
No full textAim of the present paper was to investigate the influence of preparation parameters on the production of lipospheres (LS) for drug delivery. LS composed of triglycerides and monoglycerides were alternatively produced by melt dispersion technique, solvent evaporation or w/o/w double emulsion method. The influence of preparation parameters, such as (a) type and amount of lipids, (b) presence and concentration of surfactants, (c) stirring speed and (d) type of stirrer was studied. In the case of LS prepared by melt dispersion, the use of a lipid composition of cetyl alcohol/cholesterol (2:1, w/w), a 5% (w/w) gelatin solution (50 bloom grades) and 1000rpm stirring speed resulted in the production of spherical particles, with high percentage of recovery (82%, w/w) a mean diameter of 80μm and a narrow size distribution. In the case of LS prepared by solvent evaporation, the best results in terms of LS morphology, recovery and size distribution were obtained by the use of a lipid composition of tristearin/monostearate (66:34, w/w), a 1% (w/w) PVA solution, a 750rpm stirring speed and a 55mm three-blade turbine rotor.The solvent evaporation method resulted in the production of LS characterised by a smaller size (20μm mean diameter) but poor mechanical properties with respect to particles with the same composition obtained by the melt dispersion technique (170μm mean diameter). The use of a combination of lipids and a methacrylic polymer (Eudragit RS 100) overcame this problem, resulting in the production of spherical particles, with a narrower size distribution and good mechanical properties.Two lipophilic drugs, such as retinyl acetate and progesterone, and one hydrophilic drug, sodium cromoglycate (SCG), were encapsulated in LS as model compounds. Lypophilic drugs displayed satisfactory encapsulation efficiencies (over 70%w/w), while SCG was very scarcely encapsulated (about 2%w/w). To solve this drawback, the use of a w/o/w double emulsion strategy was proposed, enabling to increase the encapsulation of SCG up to 50%w/w.Finally, in vitro drug release studies were performed, showing that all drugs were released in a control manner. In particular, the retinyl acetate release efficacy within the first 8h was 27% of the total amount of the drug, while in the same period, the amount of progesterone released was 63%. With regard to SCG containing LS, the release of the drug was largely influenced by the type of stabiliser of the primary emulsion, in any case the SCG release reached the 100% of the total amount of drug after 5h from the beginning of the experiment. Copyright © 2002 Elsevier Science Ltd
The Social Cost-of-Living: Welfare Foundations and Estimation
No full textWe present a new class of social cost-of-living indices and a nonparametric framework for estimating these and other social cost-of- living indices. Common social cost-of-living indices can be understood as aggregator functions of approximations of individual cost-of-living indices. The Consumer Price Index (CPI) is the expenditure-weighted average of first-order approximations of each individual’s cost-of-living index. This is troubling for three reasons. First, it has not been shown to have a welfare economic foundation for the case where agents are heterogeneous (as they clearly are.) Second, it uses an expenditure-weighted average which downweights the experience of poor households relative to rich households. Finally, it uses only first-order approximations of each individual’s cost-of-living index, and thus ignores substitution effects. We propose a “common-scaling” social cost-of-living index, which is defined as the single scaling to everyone’s expenditure which holds social welfare constant across a price change. Our approach has an explicit social welfare foundation and allows us to choose the weights on the costs of rich and poor households. We also give a unique solution for the welfare function for the case where the weights are independent of household expenditure. A first order approximation of our social cost-of- living index nests as special cases commonly used indices such as the CPI. We also provide a nonparametric method for estimating second- order approximations (which account for substitution effects).Inflation, Social cost-of-living, Demand, Average Derivatives
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