Climate, conflict and forced migration

Despite the lack of robust empirical evidence, a growing number of media reports attempt to link climate change to the ongoing violent conflicts in Syria and other parts of the world, as well as to the migration crisis in Europe. Exploiting bilateral data on asylum seeking applications for 157 countries over the period 2006–2015, we assess the determinants of refugee flows using a gravity model which accounts for endogenous selection in order to examine the causal link between climate, conflict and forced migration. Our results indicate that climatic conditions, by affecting drought severity and the likelihood of armed conflict, played a significant role as an explanatory factor for asylum seeking in the period 2011–2015. The effect of climate on conflict occurrence is particularly relevant for countries in Western Asia in the period 2010–2012 during when many countries were undergoing political transformation. This finding suggests that the impact of climate on conflict and asylum seeking flows is limited to specific time period and contexts

Assessing genetic polymorphisms using DNA extracted from cells present in saliva samples

<p>Abstract</p> <p>Background</p> <p>Technical advances following the Human Genome Project revealed that high-quality and -quantity DNA may be obtained from whole saliva samples. However, usability of previously collected samples and the effects of environmental conditions on the samples during collection have not been assessed in detail. In five studies we document the effects of sample volume, handling and storage conditions, type of collection device, and oral sampling location, on quantity, quality, and genetic assessment of DNA extracted from cells present in saliva.</p> <p>Methods</p> <p>Saliva samples were collected from ten adults in each study. Saliva volumes from .10-1.0 ml, different saliva collection devices, sampling locations in the mouth, room temperature storage, and multiple freeze-thaw cycles were tested. One representative single nucleotide polymorphism (SNP) in the catechol-<it>0</it>-methyltransferase gene (COMT rs4680) and one representative variable number of tandem repeats (VNTR) in the serotonin transporter gene (5-HTTLPR: serotonin transporter linked polymorphic region) were selected for genetic analyses.</p> <p>Results</p> <p>The smallest tested whole saliva volume of .10 ml yielded, on average, 1.43 ± .77 μg DNA and gave accurate genotype calls in both genetic analyses. The usage of collection devices reduced the amount of DNA extracted from the saliva filtrates compared to the whole saliva sample, as 54-92% of the DNA was retained on the device. An "adhered cell" extraction enabled recovery of this DNA and provided good quality and quantity DNA. The DNA from both the saliva filtrates and the adhered cell recovery provided accurate genotype calls. The effects of storage at room temperature (up to 5 days), repeated freeze-thaw cycles (up to 6 cycles), and oral sampling location on DNA extraction and on genetic analysis from saliva were negligible.</p> <p>Conclusions</p> <p>Whole saliva samples with volumes of at least .10 ml were sufficient to extract good quality and quantity DNA. Using 10 ng of DNA per genotyping reaction, the obtained samples can be used for more than one hundred candidate gene assays. When saliva is collected with an absorbent device, most of the nucleic acid content remains in the device, therefore it is advisable to collect the device separately for later genetic analyses.</p

Robust acoustic particle manipulation: a thin-reflector design for moving particles to a surface

Existing ultrasonic manipulation devices capable of pushing particles to a surface (“quarter-wave” devices) have significant potential in sensor applications. A configuration for achieving this that uses the first thickness resonance of a layered structure with both a thin reflector layer and thin-fluid layer is described here. Crucially, this mode is efficient with lossy reflector materials such as polymers, produces a more uniform acoustic radiation force at the reflector, and is less sensitive to geometric variations than previously described quarter-wave devices. This design is thus expected to be suitable for mass produced, disposable device

Significance of salivary adrenomedullin in the maintenance of oral health: Stimulation of oral cell proliferation and antibacterial properties

Adrenomedullin (ADM) promotes epithelial cell proliferation and antimicrobial activity in the gastrointestinal tract. Since ADM is also present in saliva, it was the objective of our study to investigate the role of salivary ADM in the maintenance of oral health. We found mRNA for ADM and the specific receptors CRLR-RAMP2 and CRLR-RAMP3 expressed by the salivary glands and by oral keratinocytes. The hormone was detected in the glandular tissues by western blot, being slightly bigger than the synthetic peptide, indicating a posttranlational modification. ADM was localized using immunohistochemistry and immunofluorescence. Staining specific for ADM was observed near the cell nuclei of the salivary ducts and acini. There was no correlation between ADM from matched saliva and serum of healthy volunteers. The physiological role of salivary ADM in the oral cavity was investigated by incubating buccal keratinocytes with ADM and measurement of the cell proliferation using bromodeoxyuridine (BrDU) assays. There was a significant, dose dependant increase (up to 5-fold; p<0.001) of the BrDU incorporation after stimulation with ADM (1.5 to 50 ng/mL). The antibacterial properties of salivary ADM was studied by incubation of Gram+ and Gram- bacteria and yeast, isolated from human oral flora, with ADM (0.01-1000 ng/mL) for 24 h. Bacterial growth was inhibited dose dependently (p<0.001), whereas the yeast was not affected. This finding was consistent when using radial growth inhibition test on agarose plates as well as photometric measurement in microtiter plates. Our findings suggest an important role of salivary ADM in the maintenance of oral health, being involved as well as in oral cell proliferation and anti-bacterial defense

Efficient finite element modeling of radiation forces on elastic particles of arbitrary size and geometry

A finite element based method is presented for calculating the acoustic radiation force on arbitrarily shaped elastic and fluid particles. Importantly for future applications, this development will permit the modeling of acoustic forces on complex structures such as biological cells, and the interactions between them and other bodies. The model is based on a non-viscous approximation, allowing the results from an efficient, numerical, linear scattering model to provide the basis for the second-order forces. Simulation times are of the order of a few seconds for an axi-symmetric structure. The model is verified against a range of existing analytical solutions (typical accuracy better than 0.1%), including those for cylinders, elastic spheres that are of significant size compared to the acoustic wavelength, and spheroidal particles

Modelling for the robust design of layered resonators for ultrasonic particle manipulation

Several approaches have been described for the manipulation of particles within an ultrasonic field. Of those based on standing waves, devices in which the critical dimension of the resonant chamber is less than a wavelength are particularly well suited to microfluidic, or “lab on a chip” applications. These might include pre-processing or fractionation of samples prior to analysis, formation of monolayers for cell interaction studies, or the enhancement of biosensor detection capability. The small size of microfluidic resonators typically places tight tolerances on the positioning of the acoustic node, and such systems are required to have high transduction efficiencies, for reasons of power availability and temperature stability. Further, the expense of many microfabrication methods precludes an iterative experimental approach to their development. Hence, the ability to design sub-wavelength resonators that are efficient, robust and have the appropriate acoustic energy distribution is extremely important. This paper discusses one-dimensional modelling used in the design of ultrasonic resonators for particle manipulation and gives example of their uses to predict and explain resonator behaviour. Particular difficulties in designing quarter wave systems are highlighted, and modelling is used to explain observed trends and predict performance of such resonators, including their performance with different coupling layer materials