The Nature of Jets in Powerful Radio Galaxies

Relativistic plasma ejected from SMBHs at the centres of galaxies is known to play a key role in the AGN feedback cycle, and consequently the formation and evolution of structure in the universe. However, the physics driving the observed jet structure in these cosmic outflows remains an open question. As part of a project that aims to resolve some of these key questions in extragalactic jet physics, this thesis presents high resolution and sensitivity studies on the nature of jets in two known powerful FR I radio galaxies (3C465 & 3C83.1B), using the first ever deep transverse resolved radio observations of these objects from e-MERLIN, and with complementary observations from the EVLA. Our radio images represent the highest resolution and sensitivity maps of 3C465 to date, and compared with previous observations, our highest resolution (e-MERLIN only) map shows that there exist multiple bright knotty structures at the base of the NW jet in 3C465. A detailed description of the overall radio structure is presented. We measure sidedness ratio of 14.85, and consequently derive lower and upper limit values of 0.5c and 61o respectively for the jet velocity, βj and angle to the line of sight, θ in 3C465. We also use matched-resolution images across two frequencies (~1.5 and ~8.5 GHz) to construct accurate, spatially resolved spectral index image of the radio source and consequently derive the characteristic spectra across the entire radio galaxy (jet, hotspots and plumes). Our results shows that the jet spectra are fairly constant ( = -0.7), and the observed spectral flattening within the first 4.42 kpc radius from the core coincides with the region hosting the bright knots, and is consistent with the site of X-ray particle acceleration observed at the base of the radio jet in previous studies. There is very little dispersion ( = -0.04) between the spectra of the two hotspot components, plausibly indicating that electron populations of the same ages are injected at these sites. Our spectral profiles suggest that the NW and SE plumes in 3C465 are approximately homologous structures, in spite of the striking asymmetry in their physical size and shape. We attribute this asymmetry in morphology to 2-D projection effects, while variations in mass injection and propagation in external pressure and density gradients in the two regions account for the comparatively steeper spectrum in the NW plume, = -1.43 compared with the SE plume, = -1.38. Overall, our results show that first-order Fermi process at mildly relativistic shocks is the most likely acceleration mechanism at play in the radio source 3C465; and consistent with previous works, we conclude that two plausible acceleration mechanisms; (a) when bulk flow speeds, βj ≥ 0.5, and (b) when flow speeds, βj are less than ≈ 0.5 exist in our radio sample. Whereas the first case can accelerate electrons to high Lorentz factors, the second scenario dominates at slower speeds and larger distances. As extension of this work, we aim to undertake a detailed study of the radio source 3C83.1B and statistically compare the synchrotron spectra in the two samples, in order to check for any discrepancy. We also note for further study, the so called deviations from power law spectra which are indicators of synchrotron ageing and plausible diagnostics of the acceleration mechanism in order to place greater constraints on the nature of jet-particle acceleration in these sources; and in addition, polarization studies to investigate the orientation and degree of ordering of magnetic field in driving the evolution of the radio jets in these powerful FR I sources

Preparation Of Cyclohexenones From Acyclic (pentadienyl)iron(1+) Cations: Synthesis Of Carvone Metabolites And Synthetic Studies Directed Toward Dihydrotachysterols

ABSTRACT PREPARATION OF CYCLOHEXENONES FROM ACYCLIC (PENTADIENYL)IRON(1+) CATIONS: SYNTHESIS OF CARVONE METABOLITES AND SYNTHETIC STUDIES DIRECTED TOWARD DIHYDROTACHYSTEROLS Charles Felix Manful, BSc. Marquette University, 2013 Six-membered carbocycles are abundant in natural products. This structural feature is present in terpenes, secosteroids, antibiotics, and even imbedded in the polycyclic framework of complex alkaloids. A wide variety of methodologies have been utilized for the preparation of six-membered carbocycles including Robinson annulation, Diels-Alder cycloaddition, Dieckmann condensation, ring closing metathesis, photochemical carbonylation of alkenylcyclopropanes, addition of soft nucleophiles to acyclic (ç5-pentadienyl)iron cations, etc. Acyclic (ç5-pentadienyl)iron(+1) cations were first prepared about 50 years ago. The reactivity of these complexes is of continuing interest, particularly for the synthesis of conjugated polyenes and 2-cyclohexenones. These types of cationic complexes are powerful electrophiles and the site of nucleophilic attack is dependent on substituents on the pentadienyl ligand, the nature of the nucleophile, counter ion and spectator ligands on the complex. Tricarbonyl(ç5-1-methylpentadienyl)iron(+1), tricarbonyl(ç5-1-phenylpentadienyl)iron(+1), tricarbonyl(ç5-3-methylpentadienyl)iron(+1), and tricarbonyl(ç5-1,5-dimethylpentadienyl)iron(+1) cations were prepared following literature procedures. The reactivity of these substituted acyclic (pentadienyl)iron cations with malonate, nitroacetate, sulfonate and phosphonoacetate nucleophiles were examined as potential routes to synthesis of natural product possessing six-membered carbocycles. Addition of stabilized/soft carbon nucleophiles occurs preferentially at the internal positions to afford cyclohexenones via (pentenediyl)iron intermediates. Nucleophilic addition at the terminal positions affords (2,4-dienoate)iron complexes mostly as minor products. This observed regioselectivity was explained mainly on the basis of FMO vs charge control. In order to synthesize the oxygenated terpene (±)-10-Hydroxycarvone a ketoester was synthesized in five steps starting from commercially available 2,4-hexadienal. Deprotonation of the keteoester followed by DIBAL-reduction gave (±)-10-Hydroxycarvone. Alternatively, saponification of the ketoester afforded (±)-carvonic acid. Furthermore to synthesize the dihydrotachysterol A-ring fragment, a cyclohexenone was synthesized in five steps from commercially available ethyl 3-methyl-4-oxocrotonate. Luche and catalytic reductions of the cyclohexenone gave diastereomeric mixture of cyclohexanols. Protection followed by desulfonylation of the diastereomeric mixture gave a single diastereomer. á-Selenylation of this diastereomer followed by NaIO4 oxidation gave a racemic mixture dihydrotachysterol A-ring fragments

Evaluation of ECMWF medium-range ensemble forecasts of precipitation for river basins

Providing probabilistic forecasts using Ensemble Prediction Systems has become increasingly popular in both the meteorological and hydrological communities. Compared to conventional deterministic forecasts, probabilistic forecasts may provide more reliable forecasts of a few hours to a number of days ahead, and hence are regarded as better tools for taking uncertainties into consideration and hedging against weather risks. It is essential to evaluate performance of raw ensemble forecasts and their potential values in forecasting extreme hydro-meteorological events. This study evaluates ECMWF's medium-range ensemble forecasts of precipitation over the period 1 January 2008 to 30 September 2012 on a selected midlatitude large-scale river basin, the Huai river basin (ca. 270 000 km2) in central-east China. The evaluation unit is sub-basin in order to consider forecast performance in a hydrologically relevant way. The study finds that forecast performance varies with sub-basin properties, between flooding and non-flooding seasons, and with the forecast properties of aggregated time steps and lead times. Although the study does not evaluate any hydrological applications of the ensemble precipitation forecasts, its results have direct implications in hydrological forecasts should these ensemble precipitation forecasts be employed in hydrology

Reunification in informal foster care child placement: Examining the different pathways in Ghana

Informal foster care remains the preferred alternative care option for children in many parts of the world. However, the processes of reunification in informal foster care are largely unknown. This qualitative study sought to explore the reunification processes within informal foster care in Ghana to inform child protection services for better program design for such children. Twenty interviews were conducted with reunified fostered children and their biological parents. Data from the in-depth interviews with parents and children were analyzed thematically. Three main processes of reunification were identified in this study namely; open, flexible exit plans and educational threshold arrangements. The findings show that reunification pathways are informed by the factors that informed the placement. A model of reunification, based on the study findings has been suggested to guide further studies. Child protection workers should utilize the reunification model as a framework to design services for children who are reunified in informal foster care. Researchers could also utilize the reunification model as a tool to study the outcomes for children who have been reunified. Further research should also explore measures and mechanism that are needed to integrate best practices of the informal foster care processes within the formal child protection domain

Reactivity of Acyclic (pentadienyl)iron(1+) Cations with Phosphonate Stabilized Nucleophiles: Application to the Synthesis of Oxygenated Metabolites of Carvone

The addition of phosphonate stabilized carbon nucleophiles to acyclic (pentadienyl)iron(1+) cations proceeds predominantly at an internal carbon to afford (pentenediyl)iron complexes. Those complexes bearing an electron withdrawing group at the σ-bound carbon (i.e., 13/14) are stable and isolable, while complexes which do not contain an electron withdrawing group at the σ-bound carbon undergo CO insertion, reductive elimination and conjugation of the double bond to afford cyclohexenone products (21/22). Deprotonation of the phosphonate 13/14 or 21 and reaction with paraformaldehyde affords the olefinated products. This methodology was utilized to prepare oxygenated carvone metabolites (±)-25 and (±)-26

Religion, gender and citizenship: a case study of Christian and Muslim women in the United Kingdom

Religion, gender and citizenship: a case study of Christian and Muslim women in the United Kingdo

Physicochemical and nutritional properties of rice as affected by parboiling steaming time at atmospheric pressure and variety

To elucidate the effect of different parboiling steaming time on the physicochemical and nutritional quality of rice, four varieties, NERICA1, NERICA7, IR841, and WITA4, were soaked at the same initial temperature (85°C) and steamed for 5, 15, 25, 35, and 45 min. NERICA7 steamed for 25 min recorded the highest head rice yield (71.9%). Nonparboiled IR841 recorded the shortest cooking time (17.0 min), while NERICA1 steamed for 35 min recorded the longest cooking time (26.1 min). NERICA1 steamed for 45 min was the hardest (63.2 N), while nonparboiled IR841 was the softest (28.7 N). NERICA7 recorded higher peak and final viscosities across all steaming times compared to the other varieties. NERICA7 steamed for 35 and 45 min recorded the lowest total starch (77.3%) and the highest protein (13.2%) content, respectively. NERICA7 steamed for 25 and 45 min recorded the highest phosphorus (0.166%), magnesium (572 mg/kg), and potassium (2290 mg/kg) content, respectively. We conclude that, depending on desired physicochemical and nutritional properties, specific varieties and steaming times can be selected to achieve those outcomes

Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa

Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa