538 research outputs found

    Debating Development Help: NGO Fieldworker Perspectives on Street and Urban Poor Children in Ghana

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    This ethnographic investigation of the non-governmental organization (NGO) Catholic Action for Street Children (CAS) questions the cultural appropriateness of its policies and practices. By situating CAS in a historical context of colonialism and structural adjustment reforms, I show how it is responsive to a legitimating environment that consists of private donors, international finance institutions, and the Ghanaian government, all of which put pressure on CAS to specifically target street children and to adopt a policy of choice that places primary responsibility for development on the individual child. I argue that the legitimating environment is neoliberal in orientation, especially with respect to who is identified as a recipient of aid and what type of aid the recipient should receive, and which is further connected to a global transformation in representation from the street child as innocent victim to one who is more like an adult and so responsible for his or her own choices. Through an analysis of the perspectives of CAS’s own fieldworkers, I argue that the conceptualization of street children as miniature adults promotes policies that help only more advantaged street children, masks social inequalities, and does not include children’s support networks in a formulation of aid. Based on my findings, I recommend a more participatory approach that includes fieldworkers’ ideas and perspectives in the design and implementation of CAS policies

    Postracial Remedies

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    The Supreme Court’s equal protection jurisprudence is decidedly postracial. The Court has restricted the Equal Protection Clause to intentional discrimination by the government, concluding that the Constitution does not prohibit private acts of discrimination and rejecting challenges based on disparate impact, even when rigorous statistical analysis indicates that race is likely a factor. It has held that remedying the effects of past societal discrimination is an insufficient basis for race-specific remedies such as affirmative action. It has also ended remedies of this sort designed to combat previous state-sponsored racial discrimination, such as court-ordered desegregation measures in the schools and the preclearance provisions of the Voting Rights Act. Constitutional litigation currently provides little or no recourse to address racial disparities in outcomes that are not demonstrably caused by intentional governmental racial discrimination, and race-specific remedies face a level of judicial scrutiny that is especially difficult to satisfy. This Article asks what can be done under these circumstances to ameliorate racial inequality in a manner that is politically feasible and does not run afoul of constitutional limits. It argues that “postracial remedies” are a necessary component of an effective strategy to combat racial disparities in areas such as wealth, incarceration, education, and housing. Postracial remedies seek pragmatic solutions for the economic, social, and structural problems that disproportionately burden blacks in the United States. These remedies are not race specific because they do not treat people differently based on race, but they are race sensitive because they target the manifestations of racial inequality and recognize the salience of race in today’s political and legal environment. This approach, which seeks legally achievable remedies, is also consistent with “antibalkanization” perspectives associated with “race moderates” whose civil rights equal protection jurisprudence is motivated, in part, by a concern with preserving social cohesion. Although postracial remedies are necessary within this postracial ethos, pursuing them does not require acceptance of the postracial narrative or the abandonment of advocacy to combat ongoing racial discrimination

    SoK: Cryptographically Protected Database Search

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    Protected database search systems cryptographically isolate the roles of reading from, writing to, and administering the database. This separation limits unnecessary administrator access and protects data in the case of system breaches. Since protected search was introduced in 2000, the area has grown rapidly; systems are offered by academia, start-ups, and established companies. However, there is no best protected search system or set of techniques. Design of such systems is a balancing act between security, functionality, performance, and usability. This challenge is made more difficult by ongoing database specialization, as some users will want the functionality of SQL, NoSQL, or NewSQL databases. This database evolution will continue, and the protected search community should be able to quickly provide functionality consistent with newly invented databases. At the same time, the community must accurately and clearly characterize the tradeoffs between different approaches. To address these challenges, we provide the following contributions: 1) An identification of the important primitive operations across database paradigms. We find there are a small number of base operations that can be used and combined to support a large number of database paradigms. 2) An evaluation of the current state of protected search systems in implementing these base operations. This evaluation describes the main approaches and tradeoffs for each base operation. Furthermore, it puts protected search in the context of unprotected search, identifying key gaps in functionality. 3) An analysis of attacks against protected search for different base queries. 4) A roadmap and tools for transforming a protected search system into a protected database, including an open-source performance evaluation platform and initial user opinions of protected search.Comment: 20 pages, to appear to IEEE Security and Privac

    Production of membrane proteins in yeast

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    Background Yeast is an important and versatile organism for studying membrane proteins. It is easy to cultivate and can perform higher eukaryote-like post-translational modifications. S. cerevisiae has a fully-sequenced genome and there are several collections of deletion strains available, whilst P. pastoris can produce very high cell densities (230 g/l). Results We have used both S. cerevisiae and P. pastoris to over-produce the following His6 and His10 carboxyl terminal fused membrane proteins. CD81 – 26 kDa tetraspanin protein (TAPA-1) that may play an important role in the regulation of lymphoma cell growth and may also act as the viral receptor for Hepatitis C-Virus. CD82 – 30 kDa tetraspanin protein that associates with CD4 or CD8 cells and delivers co-stimulatory signals for the TCR/CD3 pathway. MC4R – 37 kDa seven transmembrane G-protein coupled receptor, present on neurons in the hypothalamus region of the brain and predicted to have a role in the feast or fast signalling pathway. Adt2p – 34 kDa six transmembrane protein that catalyses the exchange of ADP and ATP across the yeast mitochondrial inner membrane. Conclusion We show that yeasts are flexible production organisms for a range of different membrane proteins. The yields are such that future structure-activity relationship studies can be initiated via reconstitution, crystallization for X-ray diffraction or NMR experiments

    Making Legacy Thermal Storage Heating fit for the Smart Grid

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    Collaborative paper with Oxford University Environmental Change Institute and Energy Local Ltd. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Thermal storage heaters, charged using overnight off-peak electricity, have been used for domestic space heating in the UK and other countries since the 1980s. However, they have always been difficult for consumers to manage efficiently and, with the advent of a high proportion of renewables in the electricity generation mix, the time of day when they are charged needs to be more flexible. There is also a need to reduce peaks in the demand profile to allow distribution networks to support new sources of demand such as electric vehicles. We describe a trial of a smart control system that was retrofitted to a group of six dwellings with this form of heating, with the objectives of providing more convenient and efficient control for the users while varying the times at which charging is performed, to flatten the profile of demand and make use of locally-generated renewable electricity. The trial also employs a commercially-realistic combination of a static time-of-day tariff with a real time tariff dependent on local generation, to provide consumers with the opportunity and incentive to reduce their costs by varying times of use of appliances. Results from operation over the 2015-16 heating season indicate that the objectives are largely achieved. It is estimated that on an annualised and weather-adjusted basis most of the users have consumed less electricity than before intervention and their costs are less on the trial tariffs. Critical factors for success of this form of system are identified, particularly the need to facilitate hands-on control of heating by thrifty users and the importance of an effective and sustained user engagement programme when introducing the technology, to ensure users gain confidence through a readily-accessible source of support and advice

    Which yeast species shall I choose? Saccharomyces cerevisiae versus Pichia pastoris (review)

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    Having decided on yeast as a production host, the choice of species is often the first question any researcher new to the field will ask. With over 500 known species of yeast to date, this could pose a significant challenge. However, in reality, only very few species of yeast have been employed as host organisms for the production of recombinant proteins. The two most widely used, Saccharomyces cerevisiae and Pichia pastoris, are compared and contrasted here

    Phylogenomics and analysis of shared genes suggest a single transition to mutualism in Wolbachia of nematodes

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    Wolbachia, endosymbiotic bacteria of the order Rickettsiales, are widespread in arthropods but also present in nematodes. In arthropods, A and B supergroup Wolbachia are generally associated with distortion of host reproduction. In filarial nematodes, including some human parasites, multiple lines of experimental evidence indicate that C and D supergroup Wolbachia are essential for the survival of the host, and here the symbiotic relationship is considered mutualistic. The origin of this mutualistic endosymbiosis is of interest for both basic and applied reasons: How does a parasite become a mutualist? Could intervention in the mutualism aid in treatment of human disease? Correct rooting and high-quality resolution of Wolbachia relationships are required to resolve this question. However, because of the large genetic distance between Wolbachia and the nearest outgroups, and the limited number of genomes so far available for large-scale analyses, current phylogenies do not provide robust answers. We therefore sequenced the genome of the D supergroup Wolbachia endosymbiont of Litomosoides sigmodontis, revisited the selection of loci for phylogenomic analyses, and performed a phylogenomic analysis including available complete genomes (from isolates in supergroups A, B, C, and D). Using 90 orthologous genes with reliable phylogenetic signals, we obtained a robust phylogenetic reconstruction, including a highly supported root to the Wolbachia phylogeny between a (A + B) clade and a (C + D) clade. Although we currently lack data from several Wolbachia supergroups, notably F, our analysis supports a model wherein the putatively mutualist endosymbiotic relationship between Wolbachia and nematodes originated from a single transition event

    Developing a scalable model of recombinant protein yield from Pichia pastoris: the influence of culture conditions, biomass and induction regime

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    <p>Abstract</p> <p>Background</p> <p>The optimisation and scale-up of process conditions leading to high yields of recombinant proteins is an enduring bottleneck in the post-genomic sciences. Typical experiments rely on varying selected parameters through repeated rounds of trial-and-error optimisation. To rationalise this, several groups have recently adopted the 'design of experiments' (DoE) approach frequently used in industry. Studies have focused on parameters such as medium composition, nutrient feed rates and induction of expression in shake flasks or bioreactors, as well as oxygen transfer rates in micro-well plates. In this study we wanted to generate a predictive model that described small-scale screens and to test its scalability to bioreactors.</p> <p>Results</p> <p>Here we demonstrate how the use of a DoE approach in a multi-well mini-bioreactor permitted the rapid establishment of high yielding production phase conditions that could be transferred to a 7 L bioreactor. Using green fluorescent protein secreted from <it>Pichia pastoris</it>, we derived a predictive model of protein yield as a function of the three most commonly-varied process parameters: temperature, pH and the percentage of dissolved oxygen in the culture medium. Importantly, when yield was normalised to culture volume and density, the model was scalable from mL to L working volumes. By increasing pre-induction biomass accumulation, model-predicted yields were further improved. Yield improvement was most significant, however, on varying the fed-batch induction regime to minimise methanol accumulation so that the productivity of the culture increased throughout the whole induction period. These findings suggest the importance of matching the rate of protein production with the host metabolism.</p> <p>Conclusion</p> <p>We demonstrate how a rational, stepwise approach to recombinant protein production screens can reduce process development time.</p

    19F NMR spectroscopy monitors ligand binding to recombinantly fluorine-labelled b'x from human protein disulphide isomerase (hPDI)

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    We report a protein-observe (19)F NMR-based ligand titration binding study of human PDI b'x with ?-somatostatin that also emphasises the need to optimise recombinant protein fluorination when using 5- or 6-fluoroindole. This study highlights a recombinant preference for 5-fluoroindole over 6-fluoroindole; most likely due to the influence of fluorine atomic packing within the folded protein structure. Fluorination affords a single (19)F resonance probe to follow displacement of the protein x-linker as ligand is titrated and provides a dissociation constant of 23 ± 4 ?M

    A Comprehensive Benchmarking Study of Protocols and Sequencing Platforms for 16s Rrna Community Profiling

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    In the last 5 years, the rapid pace of innovations and improvements in sequencing technologies has completely changed the landscape of metagenomic and metagenetic experiments. Therefore, it is critical to benchmark the various methodologies for interrogating the composition of microbial communities, so that we can assess their strengths and limitations. The most common phylogenetic marker for microbial community diversity studies is the 16S ribosomal RNA gene and in the last 10 years the field has moved from sequencing a small number of amplicons and samples to more complex studies where thousands of samples and multiple different gene regions are interrogated. Results: Weassembled2syntheticcommunitieswithaneven(EM)anduneven(UM)distributionofarchaealand bacterial strains and species, as metagenomic control material, to assess performance of different experimental strategies. The 2 synthetic communities were used in this study, to highlight the limitations and the advantages of the leading sequencing platforms: MiSeq (Illumina), The Pacific Biosciences RSII, 454 GS-FLX/+ (Roche), and IonTorrent (Life Technologies). We describe an extensive survey based on synthetic communities using 3 experimental designs (fusion primers, universal tailed tag, ligated adaptors) across the 9 hypervariable 16S rDNA regions. We demonstrate that library preparation methodology can affect data interpretation due to different error and chimera rates generated during the procedure. The observed community composition was always biased, to a degree that depended on the platform, sequenced region and primer choice. However, crucially, our analysis suggests that 16S rRNA sequencing is still quantitative, in that relative changes in abundance of taxa between samples can be recovered, despite these biases. Conclusion: Wehaveassessedarangeofexperimentalconditionsacrossseveralnextgenerationsequencing platforms using the most up-to-date configurations. We propose that the choice of sequencing platform and experimental design needs to be taken into consideration in the early stage of a project by running a small trial consisting of several hypervariable regions to quantify the discriminatory power of each region. We also suggest that the use of a synthetic community as a positive control would be beneficial to identify the potential biases and procedural drawbacks that may lead to data misinterpretation. The results of this study will serve as a guideline for making decisions on which experimental condition and sequencing platform to consider to achieve the best microbial profiling
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