Dynamic sustainability assessment of countries at the macro level: A principal component analysis

Monitoring progress toward sustainable development requires the identification of operational indicators that provide manageable units of information on institutional, environmental, economic and social dimensions. This paper is an attempt to develop macro sustainability indicators of selected countries in order to track sustainability in a dynamic manner. Therefore, as a first step, sustainability pillar variables for 131 countries were defined and derived for the period 2000–2007. Three different methods, i.e., standardization, min–max and cyclical techniques, were used to normalize data and finally a principal component analysis (PCA) was applied for weighting selected variables. In the last step, countries were ranked based on their principal components (PCs) and spatially aggregated sustainability was tracked in four dimensions. The paper finds that while progress was observed for the institutional, economic and social dimensions, the environmental conditions deteriorated successively over the studied period. It is concluded that when institutional, environmental and economic pillars are strongly correlated, economic development cannot solely explain environmental deterioration.     

Causality between pillars of sustainable development: Global stylized facts or regional phenomena?

Since the Brundtland report, most governments have committed themselves to sustainable development. For this purpose, different global and national organizations and institutions have tried to find the relationships, and especially causalities, between sustainability pillars, which are interesting for them from a policy point of view. With respect to their findings, some questions need to be answered before appropriate policies can be formulated. Are causalities between sustainability pillars global stylized facts or regional phenomena? Can countries with different characteristics follow the same rules, or are causalities between the pillars sensitive to the regional and intrinsic features of countries? Using principal component analysis for the construction of sustainability indicators and the Granger causality model (GMM approach) for testing the causalities between sustainability pillars in different samples, this study finds that causal patterns among the pillars of sustainability are completely sensitive to the characteristics of the countries that are grouped. Therefore, it is recommended that researchers concentrate more on homogeneous case studies and avoid generalizations of causal relationships between sets of heterogeneous countries.     

Genetic analysis of HIV-1 subtypes in Nairobi, Kenya

Background

Genetic analysis of a viral infection helps in following its spread in a given population, in tracking the routes of infection and, where applicable, in vaccine design. Additionally, sequence analysis of the viral genome provides information about patterns of genetic divergence that may have occurred during viral evolution.

Objective

In this study we have analyzed the subtypes of Human Immunodeficiency Virus -1 (HIV-1) circulating in a diverse sample population of Nairobi, Kenya.

Methodology

69 blood samples were collected from a diverse subject population attending the Aga Khan University Hospital in Nairobi, Kenya. Total DNA was extracted from peripheral blood mononuclear cells (PBMCs), and used in a Polymerase Chain Reaction (PCR) to amplify the HIV gag gene. The PCR amplimers were partially sequenced, and alignment and phylogenetic analysis of these sequences was performed using the Los Alamos HIV Database.

Results

Blood samples from 69 HIV-1 infected subjects from varying ethnic backgrounds were analyzed. Sequence alignment and phylogenetic analysis showed 39 isolates to be subtype A, 13 subtype D, 7 subtype C, 3 subtype AD and CRF01_AE, 2 subtype G and 1 subtype AC and 1 AG. Deeper phylogenetic analysis revealed HIV subtype A sequences to be highly divergent as compared to subtypes D and C.

Conclusion

Our analysis indicates that HIV-1 subtypes in the Nairobi province of Kenya are dominated by a genetically diverse clade A. Additionally, the prevalence of highly divergent, complex subtypes, intersubtypes, and the recombinant forms indicates viral mixing in Kenyan population, possibly as a result of dual infections.     

Prediction of cotton leaf curl virus disease and its management through resistant germplasm and bio-products

Cotton leaf curl virus disease reduces the cotton yield significantly every year and is transmitted by Bemisia tabaci. The study was designed to evaluate 15 varieties/lines against the disease. Multiple regression analysis was performed based on a-biotic environmental variables (maximum air temperature, minimum air temperature, relative humidity and rainfall) to predict disease incidence and its vector (Bemisia tabaci). Two bio-products were evaluated against the whitefly population to control the disease. Out of 15 cotton varieties/lines, no one was found highly resistant against the disease. Five varieties/lines (BT BT-980, BT-457, KIRAN, BT-666 and SLH-BT-6) exhibited moderately resistant response. Maximum air temperature (34–35.5 °C), minimum temperature (25.75–26.25 °C), relative humidity (64.14–66%), rainfall (1–2 mm) and wind speed (5.50–5.75 Kmh^?1) favoured the disease development. Maximum whitefly population was favoured by maximum air temperature from 34–35.5 °C, 25.8–26.2 °C minimum air temperature, 64.14–66% relative humidity, 1–2 mm from rainfall and 5.50–5.75 Kmh^?1 wind speed. Datura stramonium was found more effective as compared to Aviara (Homoeopathic) but not from the positive control (Acetamiprid).     

Influence of growth media on vancomycin resistance of Enterococcus isolates and correlation with resistance gene determinants

The effect of Mueller-Hinton (MH), MH+blood or brain heart infusion medium (agar or broth) on 13 Enterococcus isolates was determined, when testing their antibiotic susceptibility. Disk diffusion and Vitek methods were used to determine vancomycin resistance, while broth dilution and E-test methods were used to measure the minimum inhibitory concentration. The data were correlated with the presence of vancomycin resistance genes. A definite correlation pattern could not be established between the presence of van genes and vancomycin resistance in any plating medium, when tested by the disk diffusion assay. The broth dilution, irrespective of the plating medium, and Vitek methods were more reliable than the E-test method in testing isolates with vanA or vanB genes. However, for vanC2/C3 genotypes, the E-test method, irrespective of the plating medium, tested better than the broth dilution assay.     

Begomoviruses Associated with Yellow Leaf Curl Disease of Tomato in Iran*

The occurrence of Tomato yellow leaf curl virus (TYLCV; genus Begomovirus, family Geminiviridae) in the major tomato‐growing areas of Iran was determined using TAS‐ELISA and PCR. The nucleotide sequences of the coat protein (CP) gene and intergenic region (IR) of eight Iranian isolates were determined. CP nucleotide identities among the Iranian isolates were 96–98%, and showed 94–96% identity with TYLCV‐IR [IR:Ira:98] and TYLCV‐IL [IL:Reo:86]. However, they showed low identity (68–69%) with ToLCIRV‐[IR:Ira]. Sequence analyses of IR indicated that seven Iranian isolates had sequence identity of 93–100% with each other, and 76% identity with the Jiroft isolate; identities of 75–79% with TYLCV‐IR[IR:Ira:98] were observed in every case, and 59–62% identity with ToLCIRV‐[IR:Ira]. The IR nucleotide sequences of Iranian isolates showed 92–93% identity with TYLCV‐IL[IL:Reo:86], except the Jiroft isolate (75%). The CP and IR sequence analyses suggested that eight Iranian TYLCV isolates probably differ from ToLCIRV‐[IR:Ira]. Based on IR sequence comparisons and phylogenetic analyses, the Iranian isolates were divided into two groups. The first major group (A), consists of seven virus isolates, was most closely related to TYLCV‐IL[IL:Reo:86], and relatively divergent from TYLCV‐IR [IR:Ira:98] and ToLCIRV‐[IR:Ira]. However, the Jiroft isolate from group B did not show high similarity with TYLCV‐IR[IR:Ira:98], ToLCIRV‐[IR:Ira], and TYLCV‐IL[IL:Reo:86], suggesting that the isolate may be a divergent variant. The differences are in a range that suggests different strains or species from TYLCV‐IR[IR:Ira:98] and ToLCIRV‐[IR:Ira] are probably associated with tomato yellow leaf curl disease in Iran.     

Tibiofemoral kinematics and condylar motion during the stance phase of gait

Accurate knowledge of the dynamic knee motion in-vivo is instrumental for understanding normal and pathological function of the knee joint. However, interpreting motion of the knee joint during gait in other than the sagittal plane remains controversial. In this study, we utilized the dual fluoroscopic imaging technique to investigate the six-degree-of-freedom kinematics and condylar motion of the knee during the stance phase of treadmill gait in eight healthy volunteers at a speed of 0.67 m/s. We hypothesized that the 6DOF knee kinematics measured during gait will be different from those reported for non-weightbearing activities, especially with regards to the phenomenon of femoral rollback. In addition, we hypothesized that motion of the medial femoral condyle in the transverse plane is greater than that of the lateral femoral condyle during the stance phase of treadmill gait. The rotational motion and the anterior–posterior translation of the femur with respect to the tibia showed a clear relationship with the flexion–extension path of the knee during the stance phase. Additionally, we observed that the phenomenon of femoral rollback was reversed, with the femur noted to move posteriorly with extension and anteriorly with flexion. Furthermore, we noted that motion of the medial femoral condyle in the transverse plane was greater than that of the lateral femoral condyle during the stance phase of gait (17.4±2.0 mm vs. 7.4±6.1 mm, respectively; p<0.01). The trend was opposite to what has been observed during non-weightbearing flexion or single-leg lunge in previous studies. These data provide baseline knowledge for the understanding of normal physiology and for the analysis of pathological function of the knee joint during walking. These findings further demonstrate that knee kinematics is activity-dependent and motion patterns of one activity (non-weightbearing flexion or lunge) cannot be generalized to interpret a different one (gait).     

An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20–45, 45–90, 90–180 and 180–425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.KEY WORDS: DSC traces, particle size, polyox, sustained release, theophylline