Molecules as magnetic probes of starspots

Stellar dynamo processes can be explored by measuring the magnetic field. This is usually obtained using the atomic and molecular Zeeman effect in spectral lines. While the atomic Zeeman effect can only access warmer regions, the use of molecular lines is of advantage for studying cool objects. The molecules MgH, TiO, CaH, and FeH are suited to probe stellar magnetic fields, each one for a different range of spectral types, by considering the signal that is obtained from modeling various spectral types. We have analyzed the usefulness of different molecules (MgH, TiO, CaH, and FeH) as diagnostic tools for studying stellar magnetism on active G-K-M dwarfs. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and present synthetic Stokes profiles for the modeled spectral type. We modeled a star with a spot size of 10% of the stellar disk and a spot comprising either only longitudinal or only transverse magnetic fields and estimated the strengths of the polarization Stokes V and Q signals for the molecules MgH, TiO, CaH, and FeH. We combined various photosphere and spot models according to realistic scenarios. In G dwarfs, the molecules MgH and FeH show overall the strongest Stokes V and Q signals from the starspot, whereas FeH has a stronger Stokes V signal in all G dwarfs, with a spot temperature of 3800K. In K dwarfs, CaH signals are generally stronger, and the TiO signature is most prominent in M dwarfs. Modeling synthetic polarization signals from starspots for a range of G-K-M dwarfs leads to differences in the prominence of various molecular signatures in different wavelength regions, which helps to efficiently select targets and exposure times for observations.Comment: 9 pages, 5 figures, 1 tabl

Common Causes of Leakages in Parapet Roof Construction in Ghana: A Case Study from Kumasi

In Ghana, especially Kumasi, the second largest city after Accra, the country\'s capital, parapet roof construction became fashionable in building construction in the 1970\'s. It entailed hiding the roofs of buildings from view behind parapet walls. This concept is popularly known as “Bohyemu”, literally meaning “construct it inside\'” or more appropriately “hide it in”. The paper examines roof designs and their functional requirements in general and specifically discusses problems associated with parapet roof construction in the country, with particular reference to Kumasi. It outlines some examples of such roofing and their respective problem areas, which include design and poor detailing, and offers practical suggestions that may help in arresting these problems. The paper concludes by sounding a note of caution to technocrats in the building profession to be more diligent in the detailing, construction and supervision of this type of roof, as well as “diagnosing” problems of leakages associated with parapet roofs, since they are usually caused by a plethora of factors which, if not well-considered and assessed, may ultimately lead to the wrong “prescriptions” in trying to in solve them. Keywords: Parapet, Roof Design, Roof Leakage, Construction Journal of Science & Technology (Ghana) Vol. 28 (3) 2008: pp. 123-13

Black Men’s Knowledge of Prostate Cancer and Screening and Vitamin D Screening and Supplementation: Predictors of High Self-Efficacy to Talk to Medical Providers About Screening

Given a global online sample of Black men (n=194) who responded to a social media campaign and completed the study, the convenience sample of Black males (N=194) was mostly married (N=147, 75.85%), had a mean age of 49.53 years (min 40, max 76, SD=8.73), and was well educated; 24.7% (n=48) had an Associate Degree, 20.6% (n=40) had a Bachelor’s, 18% (n=35) had a Master’s, and 5.2% (n=10) had a Doctorate. The mean annual income was 4.21 for category 4 of $40,000-$49,999 (min 1, max 9, SD=1.64). Most of the participants were employed (n=188, 96.9%) and born in the United States (n=152, 78.4%). As a reflection of a global sample, if not a sample of men born in Ghana (77.3%, n=194) who were now dispersed across the globe, over two-thirds (77.3%) were born in Ghana while 78.4% (n=152) were currently living in the United States; 15.5% (n=30) were currently living in Ghana, followed by 5.1 (n=10) currently living in other countries. Key findings showed that, as a brief intervention of taking the PC-S-KT-39, as per results of four paired t-tests (Bonferroni Adjustment Significance, .05/4, p=.013), this was associated with a significant increase from pre-knowledge test to post-knowledge test (p<.000; Bonferroni Adjustment Significance, .05/4, p=.013) for (a) knowledge of prostate cancer and screening (t=-8.475, df=193, p=.000); (b) self-efficacy for talking to doctor about prostate cancer and screening (t=-9.098, df=193, p=.000); (c) knowledge of Vitamin D screening and supplementation (t=-9.748, df=193, p=.000); and (d) self-efficacy for talking about Vitamin D screening and supplementation (t=-9.384, df=193, p=.000). The study demonstrated how there is great value in contemporary times in using an online social media campaign, posting and distributing flyers in community venues (barber shops, churches), snowballing, and using smart phones to conduct global online research. Given these findings, wide dissemination via the Internet of a link to the new Prostate Cancer and Screening Knowledge Test (PC-S-KT-39) is justified. If men such as those in this study disseminate the link, the impact may be global indeed

On Steady Solutions of a generalized Whitham equation

publishedVersionPaid open acces

Design innovations towards enhancing the quality of living in multi-storey compound housing for low-income households in Kumasi, Ghana

A large number of low-income households in Kumasi, in the Ashanti Region, live in compound houses. The earlier compound houses built in mud are mostly single-storey but this has gradually metamorphosed, over the years, into multi-storey compound houses within the urban areas. This has been attributed mainly to the high land values and efforts by landlords to maximize the use of land, thereby absorbing the large number of urban poor who lack accommodation. The incidence of a large number of rooms with this kind of design enable cost of renting a room to be cheaper and thus accessible to the poor. This paper seeks to present the merits and demerits of the compound house through studies conducted by the Department of Architecture, from 1985 to 2005, as well as employing an “archito-centric” approach to solving some of the problems, especially the preparation of fufu on upper floors of the building, washing and drying of laundry, refuse disposal, cooking, circulation and storage. Keywords: multi-storey compound housing, low-income housing, design innovations, Kumasi Journal of Science and Technology Vol. 26(1) 2006: 76-8

Democracy Takes Another Step Forward in #GhanaDecides 2016

Kafui Tsekpo and Alexander Afram analyse the implications behind the 2016 general elections in Ghana

Complexity of magnetic fields on red dwarfs

Magnetic fields in cool stars can be investigated by measuring Zeeman line broadening and polarization in atomic and molecular lines. Similar to the Sun, these fields are complex and height-dependent. Many molecular lines dominating M-dwarf spectra (e.g., FeH, CaH, MgH, and TiO) are temperature -- and Zeeman -- sensitive and form at different atmospheric heights, which makes them excellent probes of magnetic fields on M dwarfs. Our goal is to analyze the complexity of magnetic fields in M dwarfs. We investigate how magnetic fields vary with the stellar temperature and how "surface" inhomogeneities are distributed in height -- the dimension that is usually neglected in stellar magnetic studies. We have determined effective temperatures of the photosphere and of magnetic features, magnetic field strengths and filling factors for nine M dwarfs (M1-M7). Our chi^2 analysis is based on a comparison of observed and synthetic intensity and circular polarization profiles. Stokes profiles were calculated by solving polarized radiative transfer equations. Properties of magnetic structures depend on the analyzed atomic or molecular species and their formation heights. Two types of magnetic features similar to those on the Sun have been found: a cooler (starspots) and a hotter (network) one. The magnetic field strength in both starspots and network is within 3 kG to 6 kG, on average it is 5 kG. These fields occupy a large fraction of M dwarf atmospheres at all heights, up to 100%. The plasma beta is less than one, implying highly magnetized stars. A combination of molecular and atomic species and a simultaneous analysis of intensity and circular polarization spectra have allowed us to better decipher the complexity of magnetic fields on M dwarfs, including their dependence on the atmospheric height. This work provides an opportunity to investigate a larger sample of M dwarfs and L-type brown dwarfs.Comment: 15 pages, 6 figure