A Geometrical Approach to Strong Gravitational Lensing in f(R) Gravity

We present a framework for the study of lensing in spherically symmetric spacetimes within the context of f(R) gravity. Equations for the propagation of null geodesics, together with an expression for the bending angle are derived for any f(R) theory and then applied to an exact spherically symmetric solution of R^n gravity. We find that for this case more bending is expected for R^n gravity theories in comparison to GR and is dependent on the value of n and the value of distance of closest approach of the incident null geodesic.Comment: 9 page

Inheritance of resistance to Sporisorium sorghi in grain sorghum

Greenhouse and field experiments were conducted in 1995, in Kansas, USA, to investigate the inheritance of resistance to covered kernel smut (Sporisorium sorghi) in sorghum cultivars B35-6, SC414 and Sureño. In all crosses, the susceptible parent was BTx623. Crosses were made between resistant and susceptible accessions to determine inheritance. Crosses between resistant accessions were used to determine if they possessed the same genes. Resistant parents remained immune to S. sorghi under both field and greenhouse conditions. The incidence (76%) of smutted panicles of BTx623 grown under greenhouse conditions was substantially higher than that in BTx623 grown in the field (2.3%). The reactions of F1 progenies of the crosses B35-6 × Sureño and Sureño × BTx623 suggest incomplete dominance of resistance. There was a very limited amount of F1 seed from the other resistant × susceptible crosses and therefore no conclusion could be reached on the reactions of their progenies to S. sorghi. A 3:1 ratio of resistant to susceptible plants was obtained in the F2 population of Sureño × BTx623, suggesting incomplete dominance. Higher smut incidence in the F1 progeny of Sureño × BTx623 was observed, indicating incomplete dominance of resistance from Sureno

Solutions for f(R) gravity coupled with electromagnetic field

In the presence of external, linear / nonlinear electromagnetic fields we integrate f(R) \sim R+2{\alpha}\surd(R+const.) gravity equations. In contrast to their Einsteinian cousins the obtained black holes are non-asymptotically flat with a deficit angle. In proper limits we obtain from our general solution the global monopole solution in f(R) gravity. The scale symmetry breaking term adopted as the nonlinear electromagnetic source adjusts the sign of the mass of the resulting black hole to be physical.Comment: 7 pages no figure, final version for publication in European Physical Journal

Covariant gravitational dynamics in 3+1+1 dimensions

We develop a 3+1+1 covariant formalism with cosmological and astrophysical applications. First we give the evolution and constraint equations both on the brane and off-brane in terms of 3-space covariant kinematical, gravito-electro-magnetic (Weyl) and matter variables. We discuss the junction conditions across the brane in terms of the new variables. Then we establish a closure condition for the equations on the brane. We also establish the connection of this formalism with isotropic and anisotropic cosmological brane-worlds. Finally we derive a new brane solution in the framework of our formalism: the tidal charged Taub-NUT-(A)dS brane, which obeys the closure condition.Comment: 35 pages 1 fig; significantly expanded with (a) new closure condition on the brane, (b) discussion of anisotropic brane-worlds, (c) stationary vacuum space-times with local rotational symmetry including (d) a new tidal charged Taub-NUT-(A)dS brane solution; published version

New Spherically Symmetric Solutions in f(R)-gravity by Noether Symmetries

Spherical symmetry for f(R)-gravity is discussed by searching for Noether symmetries. The method consists in selecting conserved quantities in form of currents that reduce dynamics of f(R)-models compatible with symmetries. In this way we get a general method to obtain constants of motion without setting a priori the form of f(R). In this sense, the Noether symmetry results a physical criterium. Relevant cases are discussed.Comment: 9 pages, accepted for publication in General Relativity and Gravitatio

Some exact solutions of F(R) gravity with charged (a)dS black hole interpretation

In this paper we obtain topological static solutions of some kind of pure $F(R)$ gravity. The present solutions are two kind: first type is uncharged solution which corresponds with the topological (a)dS Schwarzschild solution and second type has electric charge and is equivalent to the Einstein-$\Lambda$-conformally invariant Maxwell solution. In other word, starting from pure gravity leads to (charged) Einstein-$\Lambda$ solutions which we interpreted them as (charged) (a)dS black hole solutions of pure $F(R)$ gravity. Calculating the Ricci and Kreschmann scalars show that there is a curvature singularity at $r=0$. We should note that the Kreschmann scalar of charged solutions goes to infinity as $r \rightarrow 0$, but with a rate slower than that of uncharged solutions.Comment: 21 pages, 4 figures, generalization to higher dimensions, references adde

Use of AUDIT, and measures of drinking frequency and patterns to detect associations between alcohol and sexual behaviour in male sex workers in Kenya

Background: Previous research has linked alcohol use with an increased number of sexual partners, inconsistent condom use and a raised incidence of sexually transmitted infections (STIs). However, alcohol measures have been poorly standardised, with many ill-suited to eliciting, with adequate precision, the relationship between alcohol use and sexual risk behaviour. This study investigates which alcohol indicator - single-item measures of frequency and patterns of drinking (> = 6 drinks on 1 occasion), or the Alcohol Use Disorders Identification Test (AUDIT) - can detect associations between alcohol use and unsafe sexual behaviour among male sex workers. Methods: A cross-sectional survey in 2008 recruited male sex workers who sell sex to men from 65 venues in Mombasa district, Kenya, similar to a 2006 survey. Information was collected on socio-demographics, substance use, sexual behaviour, violence and STI symptoms. Multivariate models examined associations between the three measures of alcohol use and condom use, sexual violence, and penile or anal discharge. Results: The 442 participants reported a median 2 clients/week (IQR = 1-3), with half using condoms consistently in the last 30 days. Of the approximately 70% of men who drink alcohol, half (50.5%) drink two or more times a week. Binge drinking was common (38.9%). As defined by AUDIT, 35% of participants who drink had hazardous drinking, 15% harmful drinking and 21% alcohol dependence. Compared with abstinence, alcohol dependence was associated with inconsistent condom use (AOR = 2.5, 95% CI = 1.3-4.6), penile or anal discharge (AOR = 1.9, 95% CI = 1.0-3.8), and two-fold higher odds of sexual violence (AOR = 2.0, 95% CI = 0.9-4.9). Frequent drinking was associated with inconsistent condom use (AOR = 1.8, 95% CI = 1.1-3.0) and partner number, while binge drinking was only linked with inconsistent condom use (AOR = 1.6, 95% CI = 1.0-2.5). Conclusions: Male sex workers have high levels of hazardous and harmful drinking, and require alcohol-reduction interventions. Compared with indicators of drinking frequency or pattern, the AUDIT measure has stronger associations with inconsistent condom use, STI symptoms and sexual violence. Increased use of the AUDIT tool in future studies may assist in delineating with greater precision the explanatory mechanisms which link alcohol use, drinking contexts, sexual behaviours and HIV transmission

INFLUENCE OF CREATIVE ACCOUNTING PRACTICES ON TAX EVASION AMONGST SMALL AND MEDIUM ENTERPRISES IN NAKURU, KENYA

Tax evasion has become a challenge to the Kenya Revenue Authority (KRA). In April of 2018 for instance, KRA charged a business person with a KSh. 7 billion tax evasion that was undertaken through use of fraudulent accounting practices. This study thus sought to examine the influence of creative accounting practices on tax evasion amongst small and medium enterprises (SMEs) in Nakuru in Kenya. It was guided by the deterrence theory and economics of crime theory and employed descriptive research design. The study specifically targeted the owners/managers of all the 20,355 SMEs operating within Nakuru County. Nassiuma (2000) formula was employed to arrive at a sample size of 100 SMEs’owners/managers. Proportional stratified random sampling technique was used to select the 100 owners/managers of SMEs from the target population. A structured questionnaire was used to gather primary data while secondary data was collected through document analysis. Content validity of questionnaires was based on responses given by five content experts. Cronbach Alpha coefficient of 0.71 was realized as a test for reliability of the instrument. Descriptive statistics that included frequencies and percentages as well as inferential statistics such as correlation and regression analysis were employed in data analysis. The study found that creative accounting practices positively influence tax evasion amongst SMEs in Nakuru. It recommended that the KRA should enforce the use of Electronic Tax Registers to eliminate loopholes that allow for manipulation of source documents, understatement of sales figures, and overstatement of purchase figures by SME

Effect of A Community Health Worker led Intervention on Skilled Birth Care in Rural Mwingi West Sub-County, Kenya: A Quasi Experimental Study

Despite strong evidence that skilled birth care (SBC) significantly reduces maternal deaths, one in four babies worldwide are delivered without SBC. This has kept maternal mortality rates (MMR) high in sub-Saharan Africa and Kenya in particular. Kenya adopted Community Health Strategy (CHS) with the aim of improving community health services. The aim of this study was to evaluate the effect of CHS on SBC in Mwingi west sub-county, Kenya. A quasi experimental study design was conducted with 1 pretest and 2 post-test household surveys done in intervention and control sites. Sample size in each survey was 422 households. Women with a child aged 9-12 months were main respondents. Binary logistic regression analysis was used to estimate the odds of SBC utilization before and after the intervention In intervention site; SBC utilization significantly improved by 12.9% (57.9% vs. 70.5%) and women in end term survey were 1.6 times (Adj. OR=1.556, P<0.0001; 95%CI: 1.295-1.868) more likely to deliver under SBC compared to baseline. Compared to control, the proportion of women delivering under SBC in intervention site increased by 8.6%. To improve maternal and child health outcomes in Kenya, implementation of CHS should be fast tracked in all counties. Keywords: Community Health Strategy, Community Health Workers, Skilled Birth Care, Maternal and Child Healt

Diseases of improved Brachiaria grass cultivars in Kenya

Swedish International Development Cooperation Agenc