Binary Population Synthesis: Methods, Normalization, and Surprises

In this paper we present a brief overview of population synthesis methods with a discussion of their main advantages and disadvantages. In the second part, we present some recent results from synthesis models of close binary compact objects with emphasis on the predicted rates, their uncertainties, and the model input parameters the rates are most sensitive to. We also report on a new evolutionary path leading to the formation of close double neutron stars (NS), with the unique characteristic that none of the two NS ever had the chance to be recycled by accretion. Their formation rates turn out to be comparable to or maybe even higher than those of recycled NS-NS binaries (like the ones observed), but their detection probability as binary pulsars is much smaller because of their short lifetimes. We discuss the implications of such a population for gravitational-wave detection of NS-NS inspiral events, and possibly for gamma-ray bursts and their host galaxies.Comment: 15 pages, 1 figure, to appear in the proceedings ``The influence of binaries on stellar population studies'', Brussels, August 2000 (Kluwer Academic Publishers), ed. D.Vanbevere

Railway transportation as a serious source of organic and inorganic pollution

Polycyclic aromatic hydrocarbons and heavy metal (Pb, Cd, Cu, Zn, Hg, Fe, Co, Cr, Mo) contents were established in soil and plant samples collected in different areas of the railway junction Iława Główna, Poland. Soil and plant samples were collected in four functional parts of the junction, i.e. the loading ramp, main track within platform area, rolling stock cleaning bay and the railway siding. It was found that all the investigated areas were strongly contaminated with polycyclic aromatic hydrocarbons (PAHs). The PAH contamination of the soil was the highest in the railway siding and in the platform area (59,508 and 49,670 μg kg−1, respectively). In the loading ramp and cleaning bay, the PAH concentration in soil was lower but still relatively very high (17,948 and 15,376 μg kg−1, respectively). The contamination in the railway siding exceeded the average control level up to about 80 times. In the soil of all the investigated areas, four- and five-ring PAHs prevailed. The concentrations of PAHs were determined in four dominating species of plants found at the junction. The highest concentration was found in the aerial parts of Taraxacum officinale (22,492 μg kg−1) growing in the cleaning bay. The comparison of the soil contamination with PAHs in the investigated railway junction showed a very significant increase of the PAHs level since 1995. It was found that the heavy metal contamination was also very high. Pb, Zn, Hg and Cd were established at the highest levels in the railway siding area, whereas Fe concentration was the highest in the platform area. A significant increase in mercury content was observed in the cleaning bay area. The investigations proved very significant increase of contamination with PAHs and similar heavy metals contamination in comparison with the concentration determined in the same areas 13 years ago

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

In silico approach to screen compounds active against parasitic nematodes of major socio-economic importance

Infections due to parasitic nematodes are common causes of morbidity and fatality around the world especially in developing nations. At present however, there are only three major classes of drugs for treating human nematode infections. Additionally the scientific knowledge on the mechanism of action and the reason for the resistance to these drugs is poorly understood. Commercial incentives to design drugs that are endemic to developing countries are limited therefore, virtual screening in academic settings can play a vital role is discovering novel drugs useful against neglected diseases. In this study we propose to build robust machine learning model to classify and screen compounds active against parasitic nematodes.A set of compounds active against parasitic nematodes were collated from various literature sources including PubChem while the inactive set was derived from DrugBank database. The support vector machine (SVM) algorithm was used for model development, and stratified ten-fold cross validation was used to evaluate the performance of each classifier. The best results were obtained using the radial basis function kernel. The SVM method achieved an accuracy of 81.79% on an independent test set. Using the model developed above, we were able to indentify novel compounds with potential anthelmintic activity.In this study, we successfully present the SVM approach for predicting compounds active against parasitic nematodes which suggests the effectiveness of computational approaches for antiparasitic drug discovery. Although, the accuracy obtained is lower than the previously reported in a similar study but we believe that our model is more robust because we intentionally employed stringent criteria to select inactive dataset thus making it difficult for the model to classify compounds. The method presents an alternative approach to the existing traditional methods and may be useful for predicting hitherto novel anthelmintic compounds.12 page(s

Chinese herb mix Tiáo-Gēng-Tāng possesses antiaging and antioxidative effects and upregulates expression of estrogen receptors alpha and beta in ovariectomized rats

<p>Abstract</p> <p>Background</p> <p>Herb mixtures are widely used as an alternative to hormonal therapy in China for treatment of the menopausal syndrome. However, composition of these herb mixtures are complex and their working mechanism is often unknown. This study investigated the effect of Tiáo-Gēng-Tāng (TG-decoction), a Chinese herbal mixture extract, in balancing female hormones, regulating expression of estrogen receptors (ERs), and preventing aging-related tissue damage.</p> <p>Methods</p> <p>Ovariectomized 5-month-old female rats were used to model menopause and treated with either TG-decoction or conjugated estrogen for 8 weeks. Estradiol (E₂), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in serum and in the hypothalamus. Hypothalamic expression of estrogen receptor (ER) alpha and beta were studied by real-time PCR and western blotting. Total antioxidant capacity (T-AOC), oxidation indicator superoxide dismutase (SOD) activity and tissue damage parameter malondialdehyde (MDA) were measured using standard assays. Aging-related ultrastructural alterations in mitochondria were studied in all animals by transmission electron microscopy.</p> <p>Results</p> <p>TG-decoction-treatment elevated E₂and lowered FSH in serum of ovariectomized rats. The potency and efficacy of TG-decoction on the hypothalamus was generally weaker than that of conjugated estrogens. However, TG-decoction was superior in upregulating expression of ERα and β. TG-decoction increased hypothalamic SOD and T-AOC levels and decreased MDAlevels and mitochondrial damage in hypothalamic neurons.</p> <p>Conclusions</p> <p>TG-decoction balances female hormones similarly to conjugated estrogens but less effectively. However, it is superior in up regulating ERα and β and exhibits antioxidative antiaging activities. Whilst it shares similar effects with estrogen, TG-decoction also seems to have distinctive and more complex functions and activities.</p

Representing 3D Space in Working Memory: Spatial Images from Vision, Hearing, Touch, and Language

The chapter deals with a form of transient spatial representation referred to as a spatial image. Like a percept, it is externalized, scaled to the environment, and can appear in any direction about the observer. It transcends the concept of modality, as it can be based on inputs from the three spatial senses, from language, and from long-term memory. Evidence is presented that supports each of the claimed properties of the spatial image, showing that it is quite different from a visual image. Much of the evidence presented is based on spatial updating. A major concern is whether spatial images from different input modalities are functionally equivalent— that once instantiated in working memory, the spatial images from different modalities have the same functional characteristics with respect to subsequent processing, such as that involved in spatial updating. Going further, the research provides some evidence that spatial images are amodal (i.e., do not retain modality-specific features)

Modeling the accretion history of supermassive black holes

There is overwhelming evidence for the presence of supermassive black holes (SMBHs) in the centers of most nearby galaxies. The mass estimates for these remnant black holes from the stellar kinematics of local galaxies and the quasar phenomenon at high redshifts point to the presence of assembled SMBHs. The accretion history of SMBHs can be reconstructed using observations at high and low redshifts as model constraints. Observations of galaxies and quasars in the submillimeter, infrared, optical, and X-ray wavebands are used as constraints, along with data from the demography of local black holes. Theoretical modeling of the growth of black hole mass with cosmic time has been pursued thus far in two distinct directions: a phenomenological approach that utilizes observations in various wavebands, and a semi-analytic approach that starts with a theoretical framework and a set of assumptions with a view to matching observations. Both techniques have been pursued in the context of the standard paradigm for structure formation in a Cold Dark Matter dominated universe. Here, we examine the key issues and uncertainties in the theoretical understanding of the growth of SMBHs.Comment: 19 pages, 4 figures, to appear as Chapter 4 in "Supermassive Black Holes in the Distant Universe" (2004), ed. A. J. Barger, Kluwer Academic Publishers, in pres

A systematic review of the psychometric properties of self-report research utilization measures used in healthcare

<p>Abstract</p> <p>Background</p> <p>In healthcare, a gap exists between what is known from research and what is practiced. Understanding this gap depends upon our ability to robustly measure research utilization.</p> <p>Objectives</p> <p>The objectives of this systematic review were: to identify self-report measures of research utilization used in healthcare, and to assess the psychometric properties (acceptability, reliability, and validity) of these measures.</p> <p>Methods</p> <p>We conducted a systematic review of literature reporting use or development of self-report research utilization measures. Our search included: multiple databases, ancestry searches, and a hand search. Acceptability was assessed by examining time to complete the measure and missing data rates. Our approach to reliability and validity assessment followed that outlined in the <it>Standards for Educational and Psychological Testing</it>.</p> <p>Results</p> <p>Of 42,770 titles screened, 97 original studies (108 articles) were included in this review. The 97 studies reported on the use or development of 60 unique self-report research utilization measures. Seven of the measures were assessed in more than one study. Study samples consisted of healthcare providers (92 studies) and healthcare decision makers (5 studies). No studies reported data on acceptability of the measures. Reliability was reported in 32 (33%) of the studies, representing 13 of the 60 measures. Internal consistency (Cronbach's Alpha) reliability was reported in 31 studies; values exceeded 0.70 in 29 studies. Test-retest reliability was reported in 3 studies with Pearson's <it>r </it>coefficients > 0.80. No validity information was reported for 12 of the 60 measures. The remaining 48 measures were classified into a three-level validity hierarchy according to the number of validity sources reported in 50% or more of the studies using the measure. Level one measures (n = 6) reported evidence from any three (out of four possible) <it>Standards </it>validity sources (which, in the case of single item measures, was all applicable validity sources). Level two measures (n = 16) had evidence from any two validity sources, and level three measures (n = 26) from only one validity source.</p> <p>Conclusions</p> <p>This review reveals significant underdevelopment in the measurement of research utilization. Substantial methodological advances with respect to construct clarity, use of research utilization and related theory, use of measurement theory, and psychometric assessment are required. Also needed are improved reporting practices and the adoption of a more contemporary view of validity (<it>i.e.</it>, the <it>Standards</it>) in future research utilization measurement studies.</p