Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon

We have directly observed reversal of the polarity of charged surfaces in water upon the addition of tri- and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size and lipophilicity of the ions, but is dominated by their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion.Comment: submitted to PRL, 26-04-2004 Changed the presentation of the theory at the end of the paper. Changed small error in estimate of prefactor ("w" in first version) of equation

Making Refuge

How do people whose entire way of life has been destroyed and who witnessed horrible abuses against loved ones construct a new future? How do people who have survived the ravages of war and displacement rebuild their lives in a new country when their world has totally changed? In Making Refuge Catherine Besteman follows the trajectory of Somali Bantus from their homes in Somalia before the onset in 1991 of Somalia’s civil war, to their displacement to Kenyan refugee camps, to their relocation in cities across the United States, to their settlement in the struggling former mill town of Lewiston, Maine. Tracking their experiences as "secondary migrants" who grapple with the struggles of xenophobia, neoliberalism, and grief, Besteman asks what humanitarianism feels like to those who are its objects and what happens when refugees move in next door. As Lewiston's refugees and locals negotiate co-residence and find that assimilation goes both ways, their story demonstrates the efforts of diverse people to find ways to live together and create community. Besteman’s account illuminates the contemporary debates about economic and moral responsibility, security, and community that immigration provokes. This title was made Open Access by libraries from around the world through Knowledge Unlatched

Radius and chirality dependent conformation of polymer molecule at nanotube interface

Temperature dependent conformations of linear polymer molecules adsorbed at carbon nanotube (CNT) interfaces are investigated through molecule dynamics simulations. Model polyethylene (PE) molecules are shown to have selective conformations on CNT surface, controlled by atomic structures of CNT lattice and geometric coiling energy. PE molecules form entropy driven assembly domains, and their preferred wrapping angles around large radius CNT (40, 40) reflect the molecule configurations with energy minimums on a graphite plane. While PE molecules prefer wrapping on small radius armchair CNT (5, 5) predominantly at low temperatures, their configurations are shifted to larger wrapping angle ones on a similar radius zigzag CNT (10, 0). A nematic transformation around 280 K is identified through Landau-deGennes theory, with molecule aligning along tube axis in extended conformationsComment: 19 pages, 7 figure2, submitted to journa

Making Refuge

How do people whose entire way of life has been destroyed and who witnessed horrible abuses against loved ones construct a new future? How do people who have survived the ravages of war and displacement rebuild their lives in a new country when their world has totally changed? In Making Refuge Catherine Besteman follows the trajectory of Somali Bantus from their homes in Somalia before the onset in 1991 of Somalia’s civil war, to their displacement to Kenyan refugee camps, to their relocation in cities across the United States, to their settlement in the struggling former mill town of Lewiston, Maine. Tracking their experiences as "secondary migrants" who grapple with the struggles of xenophobia, neoliberalism, and grief, Besteman asks what humanitarianism feels like to those who are its objects and what happens when refugees move in next door. As Lewiston's refugees and locals negotiate co-residence and find that assimilation goes both ways, their story demonstrates the efforts of diverse people to find ways to live together and create community. Besteman’s account illuminates the contemporary debates about economic and moral responsibility, security, and community that immigration provokes. This title was made Open Access by libraries from around the world through Knowledge Unlatched

The Case for Second Chances: A Pathway to Decarceration in Maine

The Article argues that Maine incarcerates too many people, for too long, for too many things, at too great of an expense. We offer evidence to support this claim, briefly review some of the criminal legal legislation that shaped our present reality, and show how recent efforts at reform have been, at best, only modestly successful. In concert with a growing number of expert voices across the country calling for strategies of decarceration, our goal is to demonstrate the need for second chance legislation in Maine in the form of the reinstatement of parole, an effective clemency process, a far-reaching reevaluation of custody levels, and a new revision of the Maine Criminal Code. We argue that Maine needs a restorative pathway to decarceration that would meaningfully reduce the number of people in prison and recidivism rates, while emplacing broader and more effective responses to harm than that afforded by incarceration alone

“You know that's a rip-off”: policies and practices surrounding micro-enterprises and poverty alleviation in South African township tourism

Supporting the development of small tourism businesses has been seen by policy-makers as a valuable means of alleviating poverty in South African townships. This perspective has been endorsed by several ‘responsible’ tourism businesses and academics. Following a review of the literature, this paper reports the findings of an empirical study that examined the practices of micro-business owners and the factors that shape their behaviour in two South African townships. In spite of significant visitor numbers, it finds that their narrow social networks and the imbalances of power between them and intermediaries such as travel agencies and tour operators prevent them from developing their businesses and sharing in the material gains that become available because of tourism. This analysis has important implications for local policy-makers and those advocating responsible tourism. For the former, it suggests a cessation of current initiatives in favour of greater regulation and alternative forms of investment. For the latter, it implies the need to reassess the utility of advocating responsible tourism to consumers in a context where they do not understand the dynamics which fashion what is on offer or the full implications of their choices

Creating sustained usage of household water treatment: a case study from Kagera, Tanzania

In 2014 Basic Water Needs B.V. and South Pole Group, together with the Tanzanian NGO KADERES, developed a safe drinking water project in the Kagera region in Tanzania. The focus of the project was on sustained usage of household water treatment products. The project partners decided not to invest in the products, but in the creation of sustainable supply chain for a household water filter. This meant that filters were sold through local retailers and end-users were asked to invest the expected commercial retail price. By the end of 2016 an analysis of all monitoring data showed the percentage of households still using the household water treatment product exceeded expectations. 93,1% of households owning the product between 0-1 year were still using the product and 82,7% was still using it after 1-2 years. It seems probable that the project set up has influenced the high usage rates

Direct evidence for sequence-dependent attraction between double-stranded DNA controlled by methylation

Although proteins mediate highly ordered DNA organization in vivo, theoretical studies suggest that homologous DNA duplexes can preferentially associate with one another even in the absence of proteins. Here we combine molecular dynamics simulations with single-molecule fluorescence resonance energy transfer experiments to examine the interactions between duplex DNA in the presence of spermine, a biological polycation. We find that AT-rich DNA duplexes associate more strongly than GC-rich duplexes, regardless of the sequence homology. Methyl groups of thymine acts as a steric block, relocating spermine from major grooves to interhelical regions, thereby increasing DNA-DNA attraction. Indeed, methylation of cytosines makes attraction between GC-rich DNA as strong as that between AT-rich DNA. Recent genome-wide chromosome organization studies showed that remote contact frequencies are higher for AT-rich and methylated DNA, suggesting that direct DNA-DNA interactions that we report here may play a role in the chromosome organization and gene regulationopen