On Velocity Measurements in Non-Isothermal Turbulent Flows

Turbulent velocity measurements in non-isothermal flows are conventionally performed by constant current hot-wire anemometry. The procedure involved however is cumbersome, the output signals are nonlinear and more critically a continuous signal of velocity fluctuations is not provided. The method described here utilizes two orthogonal wires situated a fraction of a millimeter apart. The upstream wire is operated in a low overheat, constant-current compensated mode thus providing a signal proportional to temperature while the down-stream wire, practically unaffected by the thermal wake of the first wire is operated in the constant temperature mode. Compensation for the effects of local temperature on the downstream wire is accomplished by the temperature signal obtained from the first wire. Variations of Kramers\u27 law coefficients (both being functions of density and thermal conductivities) due to temperature variations are compensated through an analog circuit at the input of the logarithmic amplifiers of the linearizer. By this method, linear and separate signals of the velocity and local temperature are thus obtained simultaneously and continuously. Advantages accruing from this method are readily adapted to cross-wire configuration thus permitting direct measurements of momentum and heat transfer in turbulent heated flows

SKILLED ARTISANAL AVAILABILITY IN THE GHANAIAN CONSTRUCTION INDUSTRY

The issue of skilled artisanal scarcity is not a current one. It dates as far back as the two world wars. This paper premised on the observation of the unavailability of skillful artisans in the Ghanaian Construction Industry (GCI). The objective of the study was to identify the factors aggravating the skilled artisanal scarcity in Ghana. Using relative important indices as the main statistical analysis tool, the following factors have been identified as the most important factors causing the scarcity situation : Irregular and low remuneration, low motivation, the lack of interest by the youth to take up trades like masonship and carpentry as professions, varying working conditions and technological advancements. The study recommends that an Association of Ghanaian Construction Artisans (AGCA) as a regulatory body to promote the welfare of its members i n other to address the issues raised by this study

Preliminary pharmacological investigation of the ischuretic property and safety of a hydro-ethanolic extract of Amaranthus spinosis (Fam: Amaranthaceae)

Background: Ischuria is a health and social problem, having a negative impact on sufferers. This study therefore was a preliminary investigation of the ischuretic property and safety for use of a hydro-ethanolic extract of Amaranthus spinosus used traditionally in managing ischuria.Methods: Phytochemical screening, thin layer chromatography and high performance liquid chromatography were performed on the extract to establish fingerprints for identification. Acetylcholine, Nicotine, and the extract were applied to an isolated rat urinary bladder to ascertain contractile response. The possible receptor site(s) of action was also investigated using isolated rabbit jejunum, and guinea-pig ileum preparations. In-house observation, hematological analysis, and liver and kidney function tests were performed on Sprague-Dawley rats, in acute and sub-acute toxicity studies.Results: The extract had contractile effects on the rat urinary bladder (similar to acetylcholine and nicotine) and rabbit jejunum. Its contractile effect of the guinea-pig ileum was significantly inhibited by hexamethonium (77.50 ± 8.50 %; P ≤ 0.001) and to a lesser extent by mepyramine (49.2 ± 6.80 %; P ≤ 0.001) and Atropine (22.45 ± 5.22 %; P ≤ 0.01). The extract (80-800 mg kg-1) was not lethal and a 160 and 240 mg kg-1 dose had no adverse effect on blood, liver, kidney metabolic function.Conclusions: The hydro-ethanolic extract of Amaranthus spinosus has ischuretic activity possibly mediated via nicotinic, histaminic and muscarinic receptor stimulation and is safety to use in ischuria

An experimental study on wistar rats to see the effect of Gymnema sylvestre on blood pressure

Background: Hypertension is a leading cause of morbidity and mortality globally. It is a well-known risk factor for an array of adverse cardiovascular outcomes. Obesity is considered as one of the major contributing factors to essential hypertension in humans. Obesity in itself is a risk factor for conditions like insulin resistance, hypertension, stroke, ischemic heart diseases, CHF etc. Undoubtedly in recent times we have achieved great advances in terms of management of hypertension but still we have miles to cover to have dominance over it. Gymnema sylvestre is a valuable indigenous herb. A number of animal and human studies have shown the potential role of Gymnema sylvestre (GS) as an anti-diabetic and anti-obesity agent.Methods: Adult Female Wistar rats, weighing between 150-200 gm, were included in the study. They were randomly divided into five groups with six rats in each group. High Fat Diet (HFD) was given for 4 weeks to induce hypertension in all the groups except group I which was fed with normal chow. Drugs along with respective diets were given to the rats for next 4 weeks by oral feeding cannula. Systolic blood pressure was measured by NIBP controller machine.Results: On feeding rats with HFD for 4 weeks the mean systolic blood pressure increased significantly. After giving drugs GS (100mg/kg), GS (200mg/kg) and Amlodipine (10mg/kg) to groups III, IV, V respectively for next 4 weeks, mean systolic blood pressure fell significantly (p <0.05) as compared to group II (HFD control group). At final evaluation at week 8 (as compared to Group 2) SBP got maximally reduced in Group 5 (35.1%) followed by Group 4 (26.4%), Group 3 (20.1%). On comparing Amlodipine standard (group 5) with other groups, a significant difference was found. This showed that Gymnema sylvestre reduced the elevated systolic blood pressure significantly but this anti-hypertensive effect was inferior to Amlodipine.Conclusions: The present study concludes that Gymnema sylvestre has a potent dose- dependent antihypertensive action but the effect is inferior to Amlodipine. Hence it can be used as an add-on to standard drugs for hypertension

Selfsimilar Domain Growth, Localized Structures and Labyrinthine Patterns in Vectorial Kerr Resonators

We study domain growth in a nonlinear optical system useful to explore different scenarios that might occur in systems which do not relax to thermodynamic equilibrium. Domains correspond to equivalent states of different circular polarization of light. We describe three dynamical regimes: a coarsening regime in which dynamical scaling holds with a growth law dictated by curvature effects, a regime in which localized structures form, and a regime in which polarization domain walls are modulationally unstable and the system freezes in a labyrinthine pattern.Comment: 13 pages, 6 figure

Wetland Health in Two Agro-Ecological Zones of Lesotho: Soil Physico-Chemical Properties, Nutrient Dynamics and Vegetation Isotopic N¹⁵

Monitoring is essential to evaluate the effects of wetland restoration projects. Assessments were carried-out after 6 years of restoration efforts on a wetland located in two agro-ecological zones (AEZ): the Mountains agro-ecological zone–Khalongla-lithunya (KHL) and the Foot Hills–Ha-Matela (HM). The former was under conservation and the latter non-conserved. Mini-pits were dug along transects for soil sampling. Runoff water was collected from installed piezometers into pre-rinsed plastic bottles with de-ionized water once a month for between 3 and 6 months. Soil and water samples were analyzed in the laboratory for Ca, Mg, K, Na, total nitrogen, and phosphorus, and soil samples were further analyzed for Cu, Fe, Zn, and Mn and vegetation isotopic N15. Water quality, soil organic matter (SOM), carbon pools, base cations, ratios (silt:clay & SOM:silt clay), texture, and N-15 isotopes were chosen as indicators. Results showed that base cations were significantly (p < 0.05) higher in the groundwater and soils of KHL wetlands compared with those from the HM. The soils of the KHL wetlands have higher (p < 0.05) clay, silt contents, SOM, and silt clay ratios compared with the HM. Furthermore, results of the N15 isotopes were between 2.52 and 2.93% (KHL) compared with 2.00 and 6.18% (HM). Similarly, the results of the δ13C showed significant negative values at KHL (28.13–28%) compared with HM (11.77–12.72%). The study concludes that after five years of rehabilitating the KHL wetlands, the soil indicators showed that restoration efforts are positive compared with the HM wetlands that are non-conserved

Phase-Locked Spatial Domains and Bloch Domain Walls in Type-II Optical Parametric Oscillators

We study the role of transverse spatial degrees of freedom in the dynamics of signal-idler phase locked states in type-II Optical Parametric Oscillators. Phase locking stems from signal-idler polarization coupling which arises if the cavity birefringence and/or dichroism is not matched to the nonlinear crystal birefringence. Spontaneous Bloch domain wall formation is theoretically predicted and numerically studied. Bloch walls connect, by means of a polarization transformation, homogeneous regions of self-phase locked solutions. The parameter range for their existence is analytically found. The polarization properties and the dynamics of walls in one- and two transverse spatial dimensions is explained. Transition from Bloch to Ising walls is characterized, the control parameter being the linear coupling strength. Wall dynamics governs spatiotemporal dynamical states of the system, which include transient curvature driven domain growth, persistent dynamics dominated by spiraling defects for Bloch walls, and labyrinthine pattern formation for Ising walls.Comment: 27 pages, 16 figure

Emotion Norms, Display Rules, and Regulation in the Akan Society of Ghana: An Exploration Using Proverbs

Proverbs are widely used by the Akan of West Africa. The current study thematically analyzed an Akan proverb compendium for proverbs containing emotion references. Of the identified proverbs, a focus on negative emotions was most typical. Emotion-focused proverbs highlighted four emotion regulation strategies: change in cognition, response modulation, situation modification, and situation selection. A subset of proverbs addressed emotion display rules restricting the expression of emotions such as pride, and emotional contagion associated with emotions such as shame. Additional themes including: social context influences on the expression and experience of emotion; expectations of emotion limits; as well as the nature of emotions were present in the proverb collection. In general, Akan emotion-related proverbs stress individual-level responsibility for affect regulation in interpersonal interactions and societal contexts

Experience and Challenges from Clinical Trials with Malaria Vaccines in Africa.

Malaria vaccines are considered amongst the most important modalities for potential elimination of malaria disease and transmission. Research and development in this field has been an area of intense effort by many groups over the last few decades. Despite this, there is currently no licensed malaria vaccine. Researchers, clinical trialists and vaccine developers have been working on many approached to make malaria vaccine available.African research institutions have developed and demonstrated a great capacity to undertake clinical trials in accordance to the International Conference on Harmonization-Good Clinical Practice (ICH-GCP) standards in the last decade; particularly in the field of malaria vaccines and anti-malarial drugs. This capacity is a result of networking among African scientists in collaboration with other partners; this has traversed both clinical trials and malaria control programmes as part of the Global Malaria Action Plan (GMAP). GMAP outlined and support global strategies toward the elimination and eradication of malaria in many areas, translating in reduction in public health burden, especially for African children. In the sub-Saharan region the capacity to undertake more clinical trials remains small in comparison to the actual need.However, sustainability of the already developed capacity is essential and crucial for the evaluation of different interventions and diagnostic tools/strategies for other diseases like TB, HIV, neglected tropical diseases and non-communicable diseases. There is urgent need for innovative mechanisms for the sustainability and expansion of the capacity in clinical trials in sub-Saharan Africa as the catalyst for health improvement and maintained