Public School Choice and Integration: Evidence from Durham, North Carolina

Using evidence from Durham, North Carolina, we examine the impact of school choice programs on racial and class-based segregation across schools. Theoretical considerations suggest that how choice programs affect segregation will depend not only on the family preferences emphasized in the sociology literature but also on the linkages between student composition, school quality and student achievement emphasized in the economics literature, and on the availability of schools of different types. Reasonable assumptions about how these factors differ for students of different races and socio-economic status suggest that the segregating choices of students from advantaged backgrounds are likely to outweigh any integrating choices by disadvantaged students. The results of our empirical analysis are consistent with these theoretical considerations. Using information on the actual schools students attend and on the schools in their assigned attendance zones, we find that schools in Durham are more segregated by race and class as a result of school choice programs than they would be if all students attended their geographically assigned schools. In addition, we find that the effects of choice on segregation by class are larger than the effects on segregation by race.

A review of cataract in stable and conflict zones in Africa

Aim. To review and explore cataract prevalence in stable and unstable countries by examining published and unpublished ocular literature about Africa from 1980 onwards.^ Methods. Searches using OVID, Proquest Dissertations, WHO, and Ebsco Host were done. The review was restricted to articles utilizing WHO definitions of blindness and low vision. Random cluster sampling technique with a minimum sample size of 1,500, and reporting causes of blindness categorized by age and gender were inclusion considerations in the selected articles. ^ Results. Blindness and low vision increased with conflict. Women and the elderly were more likely to have vision impairing cataract. Cataract was the leading cause of blindness; the prevalence range was 22%–81% for the reviewed nations.^ Conclusion. Instability was connected to higher cataract prevalence and worse visual outcome across all characteristics examined except cataract surgical rates. ^

Polybrominated diphenyl ether (PBDE) exposure in North Americans: Cause for concern?

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants (BFRs) that have been widely produced and used as flame retardants since the 1970’s in many consumer products such as carpet and drape linings, plastics used in electronics, computer and television casings and polyurethane foam used in chairs, sofas and mattresses. PBDEs are persistent organic pollutants (POPs), which, by definition, are toxic in nature, persistent in the environment and accumulative in living organisms. Animal studies have found PBDEs to cause health defects such as fetal malformations, delayed onset of puberty, decreased sperm count, behavioral changes, permanent learning and memory impairment, endocrine disruption, as well as cancer at high doses. Recent research involving humans reported that elevated breast milk PBDEs levels in their mothers are associated with cryptorchidism (absence of one or both testes from the scrotum) in newborn boys and adverse birth outcomes as well as elevated serum PBDE levels in mothers are associated with low sperm count in young men. There are three commonly manufactured PBDE commercial mixtures: Penta-, Octa-, and Deca-BDEs. Two of them (Octa- and Penta-BDEs) have been banned by the European Union and are being voluntarily phased out in the United States. However, Deca continues to be manufactured, used, and imported in the United States. This MPH thesis consists of a literature review of peer reviewed scientific articles concerned with PBDEs in the environment and in humans, as well as a discussion concerning different routes of exposure to PBDEs and their blood, milk and tissue levels as surrogates for body burdens in North Americans and in people from other countries. Results of this literature review shows PBDE levels in human blood, milk and tissues are higher in North Americans than people from other countries worldwide. To date, the highest level of PBDEs was found in a toddler’s blood in a California study. Despite the fact that PBDEs are associated with adverse health effects, and highest levels of PBDEs in North Americans, Deca-BDE is still manufactured, used and imported in the United States. There is an urgent need of new federal regulatory policy to ban completely the production, importation and use of all commercial mixtures of PBDEs.^

The influence of HIV/AIDS on the association between genital human papillomavirus and cervical cancer in HIV/AIDS infected women: A literature review

Background: With over 440 million cases of infections worldwide, genital HPV is the most frequent sexually transmitted infection. There are several types including high risk types 16, 18, 58 and 70 among others, which are known to cause cervical cell abnormality and if persistent, can lead to cervical cancer which globally, claims 288,000 lives annually. 33.4 million people worldwide are currently living with HIV/AIDS, with 22.4 million in sub-Saharan Africa where 70% of the female population living with HIV/AIDS is also found. Similar risk factors for HPV, cervical cancer and HIV/AIDS include early age at sexual debut, multiple sexual partners, infrequent condom use, history of STI and immune-suppression. ^ Objectives: To describe the role of HPV in cervical cancer development, to describe the influence of HIV/AIDS on HPV and in the development of cervical cancer and to describe the importance of preventive measures such as screening. ^ Methods: This is a literature review where data were analyzed qualitatively and a descriptive narrative style used to evaluate and present the information. The data came from searches using Pub Med, Cochrane Library, EBSCO Medline databases as well as websites such as the CDC and WHO. Articles selected were published in English over the last 10 years. Keywords used included: 'HPV, cervical cancer and HIV', 'HIV and HPV', 'HPV and cervical cancer', 'HPV infection', 'HPV vaccine', 'genital HPV', 'HIV and cervical cancer', 'prevalence of HIV and cervical cancer' and 'prevalence of cervical cancer'. ^ Results: Women with HIV/AIDS have multiple HPV types, persistent infection, are more likely to present with cervical neoplasia and are at higher risk for cervical cancer. Research also shows that HIV could affect the transmissibility of HPV and that HPV itself could also increase the susceptibility to HIV acquisition. ^ Conclusion: HIV, genital HPV and cervical cancer are all preventable. Need to emphasize programs that aim to increase HIV/AIDS, HPV and cervical cancer awareness. Stress importance of behavior modification such as frequent use of condoms, decreased sexual partners and delayed first intercourse. Facilitate programs for screening and treating HPV, male circumcision, effective management of HAART and HPV vaccination.^

Policy analysis of iron micronutrient programs at USAID: The FANTA program in East Africa and the micronutrient initiative in Bihar region of India, using comparative cost effective and cost benefit analysis

It is the aim of this paper to examine iron supplementation programs which receive funding from United States Agency for International Development (USAID) but approach combating iron deficiency anemia in two vastly different ways. A brief literature review and background information on iron deficiencies and the differences between supplementation programs and micronutrient fortification were reviewed. Two non-governmental organizations (NGO's) were examined for this paper: the Food and Nutrition Technical Assistance II (FANTA) and the MicroNutrient Initiative. The FANTA program included an educational component to their supplementation program while the MicroNutrient Initiative solely used supplementation of micronutrients to their population. Methods used were cost-benefit analysis and cost-effectiveness analysis to determine the overall effectiveness of each program in reducing iron deficiency anemia in each population, if the added costs of the incentives in the FANTA program changed the cost-effectiveness of the program compared to the MicroNutrient Initiative program and to determine which program imparted the greatest benefit to each population by reducing the disease burden in Disability Adjusted Life Years (DALY). Results showed that the unit cost of the FANTA program per person was higher than the MicroNutrient Initiative program due to the educational component. The FANTA program reduced iron deficiency anemia less overall but cost less for each percentage point of anemia decreased in their respective populations. The MicroNutrient Initiative program had a better benefit cost ratio for the populations it served. The MicroNutrient Initiative's large scale program imparted many advantages by reducing unit cost per person and decreasing iron deficiency anemia. The FANTA program was more effective at decreasing iron deficiency anemia with less money: $5,660 per 1% decrease in iron deficiency anemia versus $18,450 per 1% decrease in iron deficiency anemia for the MicroNutrient Initiative program. ^ In conclusion, economic analysis cannot measure all of the benefits associated with programs that contain an educational component or large scale supplementation. More information needs to be gathered by NGOs and reported to USAID, such as detailed prevalence rates of iron deficiency anemia among the populations served. Further research is needed to determine the effects an educational supplementation program has on compliance rates of participants and motivation to participate in supplementation programs whose aim is to decrease iron deficiency anemia in a targeted population.^

n-Alkane analyses from an transect of marine surface sediments off southwest Africa

An isobathic transect of marine surface sediments from 1°N to 28°S off southwest Africa was used to further evaluate the potential of the chain length distribution and carbon stable isotope composition of higher plant n-alkanes as proxies for continental vegetation and climate conditions. We found a strong increase in the n-C29-33 weighted mean average d13C values from -33 per mil near the equator to around -26 per mil further south. Additionally, C25-35n-alkanes reveal a southward trend of increasing average chain length from 30.0 to 30.5. The data reflect the changing contribution of plants employing different photosynthetic pathways (C3 and C4) and/or being differently influenced by the environmental conditions of their habitat. The C4 plant proportions calculated from the data (ca. 20% for rivers draining the rainforest, to ca. 70% at higher latitude) correspond to the C4 plant abundance in continental catchment areas postulated by considering prevailing wind systems and river outflows. Furthermore, the C4 plant contribution to the sediments correlates with the mean annual precipitation and aridity at selected continental locations in the postulated catchment areas, suggesting that the C4 plant fraction in marine sediments can be used to assess these environmental parameters.

Distribution of siphonophores in the upwelling area off NW Africa

Using a Bongo-Net equipped with a multiple coded closing device, the vertical distribution of siphonophores has been observed in 100 m depth intervals at 13 stations off Cap Mirik (19°N) (from 0-500 m depth). This distributional pattern of the 15 siphonophores species found is discussed in relationship to the hydrography of this upwelling region. The following main features have been observed in comparision with the warmer oceanic water offshore: (1) a lower diversity, (2) a shallower distribution of some of the deep living species die to the lower temperature in the upper 300 m an a lower transparency, (3) no contribution to acoustic scattering by physonect siphonophores.

Hydrogeological investigations in the upper Ouémé catchment in Benin, West Africa

The scope of this PhD thesis was the hydrogeological conceptualisation of the Upper Ouémé river catchment in Benin. The study area exceeds 14,500 km**2 and is underlain by a crystalline basement. At this setting the typical sequence of aquifers - a regolith aquifer at the top and a fractured bedrock aquifer at the bottom - is encountered, which is found in basement areas all over Africa and elsewhere in the world. The chosen regional approach revealed important information about the hydrochemistry and hydrogeology of this catchment. Based on the regional conceptual model a numerical groundwater flow model was designed. The numerical model was used to estimate the impact of climate change on the regional groundwater resources. This study was realised within the framework of the German interdisciplinary research project IMPETUS (English translation: "Integrated approach to the efficient management of scarce water resources in West Africa"), which is jointly managed by the German universities of Bonn and Cologne. Since the year 2000 the Upper Ouémé catchment was the principal target for investigations into the relevant processes of the regional water cycle. A first study from 2000 to 2003 (Fass, 2004, http://nbn-resolving.de/urn:nbn:de:hbz:5n-03849) focused on the hydrogeology of a small local catchment (~30 km**2). In the course of this thesis five field campaigns were underdone from the year 2004 to 2006. In the beginning of 2004 a groundwater monitoring net was installed based on 12 automatic data loggers. Manual piezometric measurements and the sampling of groundwater and surface water were realised for each campaign throughout the whole study area. Water samples were analysed for major ions, for a choice of heavy metals and for their composition by deuterium, oxygen-18 and tritium. The numerical model was performed with FEFLOW. The hydraulic and hydrochemical characteristics were described for the regolith aquifer and the bedrock aquifer. The regolith aquifer plays the role of the groundwater stock with low conductivity while the fractures of the bedrock may conduct water relatively fast towards extraction points. Flow in fractures of the bedrock depends on the connectivity of the fracture network which might be of local to subregional importance. Stable isotopes in combination with hydrochemistry proved that recharge occurs on catchment scale and exclusively by precipitation. Influx of groundwater from distant areas along dominant structures like the Kandi fault or from the Atacora mountain chain is excluded. The analysis of tritium in groundwater from different depths revealed the interesting fact of the strongly rising groundwater ages. Bedrock groundwater may possibly be much older than 50 years. Equilibrium phases of the silicate weathering products kaolinite and montmorillonite showed that the deeper part of the regolith aquifer and the bedrock aquifer feature either stagnant or less mobile groundwater while the shallow aquifer level is influenced by seasonal groundwater table fluctuations. The hydrochemical data characterised this zone by the progressive change of the hydrochemical facies of recently infiltrated rainwater on its flow path into deeper parts of the aquifers. Surprisingly it was found out that seasonal influences on groundwater hydrochemistry are minor, mainly because they affect only the groundwater levels close to the surface. The transfer of the hydrogeological features of the Upper Ouémé catchment into a regional numerical model demanded a strong simplification. Groundwater tables are a reprint of the general surface morphology. Pumping or other types of groundwater extraction would have only very local impact on the available groundwater resources. It was possible to integrate IMPETUS scenario data into the groundwater model. As a result it was shown that the impact of climate change on the groundwater resources until the year 2025 under the given conditions will be negligible due to the little share of precipitation needed for recharge and the low water needs for domestic use. Reason for concern is the groundwater quality on water points in the vicinity of settlements because of contamination by human activities as shown for the village of Dogué. Nitrate concentrations achieved in many places already alerting levels. Health risks from fluoride or heavy metals were excluded for the Upper Ouémé area.

XCO2 and XCH4 total column measurement during POLARSTERN cruise PS83 (ANT-XXIX/10), north-south gradient

A portable Fourier transform spectrometer (FTS), model EM27/SUN, was deployed onboard the research vessel Polarstern to measure the column-average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) by means of direct sunlight absorption spectrometry. We report on technical developments as well as data calibration and reduction measures required to achieve the targeted accuracy of fractions of a percent in retrieved XCO2 and XCH4 while operating the instrument under field conditions onboard the moving platform during a 6-week cruise on the Atlantic from Cape Town (South Africa, 34° S, 18° E; 5 March 2014) to Bremerhaven (Germany, 54° N, 19° E; 14 April 2014). We demonstrate that our solar tracker typically achieved a tracking precision of better than 0.05° toward the center of the sun throughout the ship cruise which facilitates accurate XCO2 and XCH4 retrievals even under harsh ambient wind conditions. We define several quality filters that screen spectra, e.g., when the field of view was partially obstructed by ship structures or when the lines-of-sight crossed the ship exhaust plume. The measurements in clean oceanic air, can be used to characterize a spurious air-mass dependency. After the campaign, deployment of the spectrometer alongside the TCCON (Total Carbon Column Observing Network) instrument at Karlsruhe, Germany, allowed for determining a calibration factor that makes the entire campaign record traceable to World Meteorological Organization (WMO) standards. Comparisons to observations of the GOSAT satellite and concentration fields modeled by the European Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) demonstrate that the observational setup is well suited to provide validation opportunities above the ocean and along interhemispheric transects.

(Table 1) Water column biogenic silica concentrations and Si isotopic composition during Marion Dufresne cruise MD166 off South Africa

Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition (d30Si) of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (Bonus-GoodHope) which includes for the first time summer d30Si signatures of suspended biogenic silica (i) for the whole water column at three stations and (ii) in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation) should satisfactorily describe the d30Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the d30Si. The failures of previous models (Rayleigh and steady state) become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1) a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2) a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large vertical silicic acid gradient, e.g. in the Polar Front Zone and at the Polar Front.