Twins Among the Low Mass Spectroscopic Binaries

We report an analysis of twins of spectral types F or later in the 9th Catalog of Spectroscopic Binaries (SB9). Twins, the components of binaries with mass ratio within 2% of 1.0, are found among the binaries with primaries of F and G spectral type. They are most prominent among the binaries with periods less than 43 days, a cutoff first identified by Lucy. Within the subsample of binaries with P<43 days, the twins do not differ from the other binaries in their distributions of periods (median P~7d), masses, or orbital eccentricities. Combining the mass ratio distribution in the SB9 in the mass range 0.6 to 0.85 Msun with that measured by Mazeh et al. for binaries in the Carney-Latham high proper motion survey, we estimate that the frequency of twins in a large sample of spectroscopic binaries is about 3%. Current theoretical understanding indicates that accretion of high specific angular momentum material by a protobinary tends to equalize its masses. We speculate that the excess of twins is produced in those star forming regions where the accretion processes were able to proceed to completion for a minority of protobinaries. This predicts that the components of a young twin may appear to differ in age and that, in a sample of spectroscopic binaries in a star formation region, the twins are, on average, older than the binaries with mass ratios much smaller than 1.Comment: Accepted by the Astronomical Journa

Convergence Language Use in Nigerian Prose as a Platform for Human Development: A Study Of Chimamanda Adichie's Purple Hibiscus

All human activities are basically language based. This is to say that humans cannot do without language both verbally and nonverbally. Development of any kind cannot take place without language, this is because, it is language that propels human activities and co-operation. Co-operation cannot occur if humans do not observe certain nuances of language use. Language as a two edged sword can either lead to human development or mar it. So, as humans, if we want to develop economically, academically, socially, spiritually, politically etcetera, we should be able to know how to manipulate our language use to bring about cooperation which in turn brings about development. In order to achieve this, the researchers advocate the use of convergence principles in communication. Twenty- convergence conversations and twenty non- convergence conversations were systematically selected from the text. The accommodation theory by Howard Giles formed the theoretical framework of the study. At the end of the textual analysis, it was discovered by the researchers that convergence communication draw communicators closer to their communicants and as a result co-operation is achieved while non- convergence communication eschew communicators. The researchers therefore recommend that language users should endeavour to apply convergence language use because with that, they can achieve any kind of development humanly possible.Key words: Language, communication, convergence, divergence, human developmen

The Taurus Boundary of Stellar/Substellar (TBOSS) Survey I: far-IR disk emission measured with Herschel

With Herschel/PACS 134 low mass members of the Taurus star-forming region spanning the M4-L0 spectral type range and covering the transition from low mass stars to brown dwarfs were observed. Combining the new Herschel results with other programs, a total of 150 of the 154 M4-L0 Taurus members members have observations with Herschel. Among the 150 targets, 70um flux densities were measured for 7 of the 7 ClassI objects, 48 of the 67 ClassII members, and 3 of the 76 ClassIII targets. For the detected ClassII objects, the median 70um flux density level declines with spectral type, however, the distribution of excess relative to central object flux density does not change across the stellar/substellar boundary in the M4-L0 range. Connecting the 70um TBOSS values with the results from K0-M3 ClassII members results in the first comprehensive census of far-IR emission across the full mass spectrum of the stellar and substellar population of a star-forming region, and the median flux density declines with spectral type in a trend analogous to the flux density decline expected for the central objects. SEDs were constructed for all TBOSS targets covering the optical to far-IR range and extending to the submm/mm for a subset of sources. Based on an initial exploration of the impact of different physical parameters; inclination, scale height and flaring have the largest influence on the PACS flux densities. From the 24um to 70um spectral index of the SEDs, 5 new candidate transition disks were identified. The steep 24um to 70um slope for a subset of 8 TBOSS targets may be an indication of truncated disks in these systems.Two examples of mixed pair systems that include secondaries with disks were measured. Finally, comparing the TBOSS results with a Herschel study of Ophiuchus brown dwarfs reveals a lower fraction of disks around the Taurus substellar population.Comment: 64 pages, 33 figures, 12 tables, accepted for publication in A&

Nutrient Composition of Mushroom: Pleurotus Ostreatus (Jacaum, ex. Fr. Kummer) grown on Different Agricultural Wastes

The study evaluated the nutrient compositions of Pleurotus ostreatus (Jacaum, ex. Fr. Kummer) grown using different agricultural waste: sawdust, sugarcane (Sacharum officinarum) peels, plantain leaves and corn cobs. The proximate compositions of P. ostreatus fruit bodies varied significantly (P≤ 0.05). Matured fruit bodies of P. ostreatus harvested from sawdust and sugarcane peel substrates had significantly (P≤ 0.05) the highest content of moisture (15.20%) and ash (5.23%) respectively. The Corn cob substrates yielded P. ostreatus with significantly (P≤ 0.05) the highest amount of protein (9.38%) and lipids (8.5%); and lowest amount of carbohydrates (51.76%). Crude fibre was found more in the fruit bodies of P. ostreatus harvested from sugarcane peel substrates (8.23%) followed by corn cobs (7.28% ). The mineral content varied significantly (P≤ 0.05) from 0.43 - 0.90, 0.12 - 0.30, 9.20 - 14.6, 7.30 -13.0 and 1.5 - 2.7 mg/100g for iron, sodium, potassium, phosphorus and calcium respectively. P. ostreatus from sugarcane peels had significantly (P≤ 0.05) the highest mineral content except for calcium. Vitamin C content ranged from 1.3 mg/100g for corn hob to 1.8mg/100g for sawdust. The study revealed that sugarcane peel and corn hob in terms of the proximate and mineral composition are better substrate for the growth of P. ostreatus. It is therefore recommended that these agricultural wastes should be used in the cultivation of P. ostreatus. Besides producing nutritious mushrooms, this will help to reduce the huge agricultural wastes within our environment that sometimes when not properly managed caused serious environmental pollution

Direct Imaging of Multiple Planets Orbiting the Star HR 8799

Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.Comment: 30 pages, 5 figures, Research Article published online in Science Express Nov 13th, 200

Gas-solid conversion of lignin to carboxylic acids

Lignin is the only source of aromatics from lignocellulosic biomass and is a potential alternative to petroleum as a sustainable source of chemicals . Lignin constitutes 15% to 40% of the dry weight of lignocellulose, but because its a complex heterogeneous molecule. Thermo-chemical processes break lignin down to light gases (CO, H2, CH4) and pyrolysis oils characterized by a wide range of compounds, which requires further processing. The challenge is to activate lignin at lower temperatures to reduce the yield of light gases and to target a narrow class of compounds. Catalysts can improve selectivity towards the target molecules at lower temperature but carbonaceous species coke the active sites within seconds and minutes. Here we describe a two stage reactor in which we oxidize and steam crack lignin in the first stage (at heating rate of 5°Cmin−1 up to 550°C) of lignin and catalytically oxidize the effluent in the second stage. We targeted carboxylic acids that have a higher market than biofuel. With a gas feed composition of 10% oxygen and 50% steam all the lignin reacted. In the second stage, vanadium catalyst cleaved the remaining lignin bonds and opened up aromatic rings to make carboxylic acids — mostly C4 acids. In the presence of vanadium pyrophosphate 24% of the lignin formed a condensable product of which 48% was maleic acid 31% C5-C8 aromatics and fumaric ,malonic and gallic acid. Only ∼ 5% of the lignin formed coke

Machine Learning Heuristic for Solving Multi-Mode Resource-Constrained Project Scheduling Problems

The non-preemptive resource-constrained project scheduling problem is considered in this work. It is assumed that each activity has many ways of execution and the objective is to find a schedule that minimizes the project’s completion time (multi-mode RCPSP). Methods that are based on priority rules do not always give the needed very good results when used to solve multi-mode RCPSP. In solving large real-life problems quickly though, these methods are absolutely necessary. Hence good methods based on priority rules to get the primary results for metaheuristic algorithms are needed. This work presents a novel method based on priority rules to calculate the primary solutions for metaheuristic algorithms. It is a machine learning approach. This algorithm first of all uses Preprocessing to reduce the project data in order to speed up the process. It then employs a mode assignment procedure to obtain the mode of each job. After which the algorithm uses machine learning priority rule to get the precedence feasible activity list of the project’s tasks. Finally, it then uses the Serial Schedule Generation Scheme to get the total completion time of the project. In our experiments, we use our algorithm to solve some problems in the literature that was solved with metaheuristic procedures. We compared our results with the initial solutions the authors started with, and our results competes favorably with the initial solutions, making our algorithm a good entry point for metaheuristic procedures

Minimization of Failed Roads - A Hybrid Resource-Constrained Project Scheduling Problem

Causes of failed roads and the reasons why most roads stay consistently failed in some nations of the world, like Nigeria, may be attributed to many factors, salient among them may be corruption and recession ultimately. Corruption in the award of road construction contracts make roads not to be properly done, to meet set standards thereby failing almost immediately they are completed. So, if corruption is minimized in awarding road construction contracts, the number of failed roads maybe minimized. This paper introduces some solution methods to minimize corruption in road construction projects so that good and sustainable roads are constructed even if there is also recession. In our experiment, we formulated the construction of real life 5km asphalt road as a hybrid resource constrained project scheduling problem (HRCPSP). Using priority based project scheduling technique, our results show the number of skilled workers needed in each period which gives the idea of the amount of fund needed in each of the periods. We constructed two Gantt diagrams: when resources are unconstrained and when resources are constrained to the minimal demand of jobs in the eligible set in each period. The unconstrained Gantt diagram helps to know the maximum amount of fund that should be released to the engineers in each period. This helps to curb corruption. The constrained Gantt diagram helps to know the minimum amount that should be released to the engineers for work to go on and the project to get to completion stage even there is recession. This helps project to be completed even if there is recession