Number Of Ha Research Articles

The Effect of Forest Fire Events on Air Quality: A Case Study of Northern Colombia

This work presents an analysis of fire events recorded in Isla Salamanca Natural Park and their impact on the air quality in the district of Barranquilla, with an emphasis on 2020 due to the increase in the number of ha burned by forest fires that year. The analysis was based on the data provided by the environmental authority for 2015–2020. The average number of ha burned in 2020 was 50% (events recorded since 2015), with a total area of fires corresponding to 256.9 ha, which is of concern considering the ecological importance of the park and its proximity to the district of Barranquilla, Colombia. The study evaluated the spatial–temporal distributions of forest fires and their possible direct effects on air quality. For 2020, it was found that the maximum hourly measurements of the Tres Ave Marias station for particulate matter less than 2.5 (135.013 µg/m3) corresponded to the recorded event that occurred in June 2020, whereas those of the Móvil station for PM10 (263.98 µg/m3) and PM2.5 (278.7 µg/m3) corresponded to the events of 28 June 2020, and 9 August 2020. These concentrations were higher than the standard values of the average maximum limits for 24 h established in the current Colombian regulations, and both events coincided with fire events reported by the environmental authorities, where a total of 249 ha of Isla Salamanca Natural Park were burned. These things considered, it was evident that the Policía station had the highest concentrations of pollutants on average.

Temporal dynamics of persistent germinal centers and memory B cell differentiation following respiratory virus infection.

SummaryFollowing infection or immunization, memory B cells (MBCs) and long-lived plasma cells provide humoral immunity that can last for decades. Most principles of MBC biology have been determined with hapten-protein carrier models or fluorescent protein immunizations. Here, we examine the temporal dynamics of the germinal center (GC) B cell and MBC response following mouse influenza A virus infection. We find that antiviral B cell responses within the lung-draining mediastinal lymph node (mLN) and the spleen are distinct in regard to duration, enrichment for antigen-binding cells, and class switching dynamics. While splenic GCs dissolve after 6 weeks post-infection, mLN hemagglutinin-specific (HA+) GCs can persist for 22 weeks. Persistent GCs continuously differentiate MBCs, with “peak” and “late” GCs contributing equal numbers of HA+ MBCs to the long-lived compartment. Our findings highlight critical aspects of persistent GC responses and MBC differentiation following respiratory virus infection with direct implications for developing effective vaccination strategies.

The numerical analysis on the variation of electric potential, electric current and Lorentz force with its influence on buoyancy-driven conjugate heat transfer and fluid flow using OpenFOAM

The development of electric potential, electric current and Lorentz force in the presence of the magnetic field in the fluid/solid domain is studied numerically. Moreover, the significance of the magnetic field and its orientation on the pattern of electric potential, electric current and the direction of the Lorentz force is observed in the enclosure. The buoyancy-driven conjugate heat transfer and fluid flow solver with Magnetohydrodynamics (MHD) is developed in open source CFD tool OpenFOAM. The buoyancy force in the enclosure is altered by varying the Rayleigh number of Ra = 104, 105, 106, at the fixed Prandtl number of Pr = 0.02. The magnetic field is imposed in the x-direction (Bx) and y-direction (By) measured by Hartmann number of Ha = 0–100. The conjugate thermal and electromagnetic coupling is considered for the fluid-wall interface in the present analysis and includes the wall thickness within the computational domain. The orientation of the magnetic field shows the asymmetric (for Bx) and symmetric pattern (for By) of an electric potential distribution in the enclosure, and hence electric current. The detailed analysis of temperature iso-surface, isotherms, streamlines, and Nusselt number variations, etc in the presence of magnetic field are discussed in detail.

Cherry production in South Africa: status quo and new initiatives

At present the main production area for cherries in South Africa is situated in the Western Cape Province, which represents about 50% of the total 262 ha that has been planted up to 2016. Previously, production centered around the Highveld region in the eastern Free State. The cherry production areas in the eastern Free State are situated at approximately 28°45’ latitude and 27°45’ longitude and 1650 m a.s.l. The Highveld region is part of the summer-rainfall area, with dry winters and below zero temperatures during winter nights. This decline in production in the Highveld region is mainly due to these adverse growing conditions. Production was also negatively affected by using the too dwarfing ‘Gisela 5’ rootstocks that were not suitable for the shallow and sandy soils. Older orchards on Mahaleb rootstock are still producing good average yields in harsh growing conditions. Current initiatives include the use of more yield efficient rootstocks like ‘Maxma 14’ and the low-chilling scion cultivars from the breeding programs in California, USA. The poor rootability of Mahaleb cuttings in the nursery and the shortages of in vitro propagated rootstocks like ‘Maxma 14’, also tempered the planting of new orchards. This problem was overcome by a mass importation of in vitro ‘Maxma 14’ from Italy, optimising the current availability of nursery trees to increase dramatically from 32,000 to 150,000 trees year-1. These new initiatives will have a positive effect increasing the number of ha in non-traditional cherry growing areas in South Africa, such as the Northern Province as well as in the warmer parts of the Western Cape Province.

Effect of vortex promoter shape on heat transfer in MHD duct flow with axial magnetic field

The heat transfer from the side-wall of a duct through which an electrically conducting fluid flows within a strong transverse magnetic field is numerically investigated using high-resolution numerical simulation. Parameter ranges considered are 0≤Ha≤2400 and 100≤Re≤3000 for a constant blockage ratio of 1/4. The gain in the heat transfer using obstacles of different geometric shapes are compared. For Ha=320, a maximum heat transfer enhancement of 78% is obtained when using the square cylinder at a modes Re=1000, while the triangular cylinder outperformed the various other vortex promoter geometries at Re = 2000 yielding a 75% improvement.. However, at a higher Hartmann number of Ha=2400, a maximum heat transfer augmentation of 16% and 40% is obtained for the triangular cylinder at Re=1000 and 2000, respectively. This suggests that for a duct flow under the influence of a strong magnetic field, the triangular obstacle is a superior heat transfer promoter geometry compared to the square or circular cylinders. A further net power analysis reveals that the heat transfer enhancement dominates over the pumping power to produce net benefits for even a modest heat transfer enhancement.

Improving Human Capacity–One of the Ways to Overcome the Decrease in Organic Farming

Aim: This paper tends to put a different perspective for the reasons that had contributed to the drop in interest for further development of organic farming in Macedonia. Anno Domini 2001 is the year considered as official beginning of organic farming in the Republic of Macedonia. Trainings were conducted, farmers associations were established and an umbrella National Association was established too. In 2005, organic farming got under the national subsidy program, but the very next 2006 was abandoned. But since then without interruptions organic farming enjoys steady and increasing governmental support. Since 2007, two National Programs were developed while the area under organic and number of organic growers recorded steady growth. Up to 2012, when first signs of losing the pace is recorded by having a drop in number of ha under organic was recorded and the number of organic growers too. The next year, 2013 was another disappointment for the sector, since the government had reduced the volume of support from € 2113000 in 2012 to € 1089430 in 2013. Reasons for the drop in interest are naturally various but one of the most significant is insufficient competent support farmers were receiving. Unfortunately, the national advisory service has very limited human capacity on this matter, and private advisors are much too small in number to cover the demand for advice. Methodology: In order to obtain real-case data number of farms were interviewed for the practice they apply in their daily operations, in order to check their understanding of what organic farming is all about. The area of intervention was the East Planning Region in Macedonia. Then, subject of analysis were the advisors at the National Extension Agency who were asked to express their opinions on answers listed in a carefully designed questionnaire, which needed to provide answers on the level of knowledge advisors possess on organic farming. Results: the results analysis on both of the surveys are driving to a conclusion that Ministry’s opinion for the drop in interest has little value, since the amount of subsidies is quite high, yet farmers are giving up. Conclusion: Specially designed program for introducing the principles of organic farming to the farmers is imperative before they would be invited to join this kind of agricultural production. Furthermore, in order to provide best possible competent support, advisors need to go through a carefully designed training procedure in order to increase their knowledge in the principles of organic farming.

Effect of pH on the electrophoretic mobility of a particle with a charge-regulated membrane in a general electrolyte solution

The electrophoretic motion of an entity comprised of a rigid, uncharged core covered by a charge-regulated membrane which simulates a biological cell, in a general a:b electrolyte solution is analyzed. The membrane carries a fixed charge which arises from the dissociation of the acidic functional group HA. We show that the higher the concentration of cations in the bulk liquid phase, the lower the absolute Donnan potential, ∣ ϕ D∣, and the lower the concentration of functional group, N 0, the lower the ∣ ϕ D∣. Also, the higher the pH, the higher the absolute electrical potential, and the greater the N 0, the lower the pH. The absolute mobility of a cell, ∣ μ∣, increases with pH, but decreases with the increase in the friction coefficient of the membrane phase, γ. For a fixed total number of HA, if γ is large, μ/ μ s is less than unity, μ s being the mobility of the corresponding rigid particle, and it decreases with the thickness of membrane d, and the inverse is true if γ is small. For a medium γ, the variation of μ/ μ s as a function of d has a local maximum, and depending upon d, it can be either greater or less than unity.