Invariance of the Null Distribution of the Multiple Coherence

In this paper we investigate the invariance of the null distribution of the multiple coherence (MC) to the statistics of the examined signals. We show that when the MC is computed between a group of signals x_i[n], i=1,...,K and a signal y[n], the null distribution of the MC is independent of the distribution of x_i[n] and y[n] if at a given frequency the joint distribution of the spectra of the segments of x_i[n] and y[n] is rotationally symmetric with respect to the rotation of the spectra of the segments of x_i[n] or y[n]. The significance of this result lies in the improvement of the multiple coherence analysis. Hitherto, the null distribution of the MC was known only for signals with the multivariate Gaussian distribution; therefore, an MC estimate could be evaluated for its statistical significance only in this limited case. With the results presented in this paper, it will be possible to evaluate the statistical significance of MC estimates for much wider class of signals

The Fate of Arsenic in Noah’s Flood

One potential consequence of Noah’s Flood would be the mobilization of toxic elements such as arsenic (As), a group 15 metalloid with a significant solubility and redox chemistry in water and a high toxicity to human beings. This paper discusses the likely chemistry of arsenic during the Flood. The Flood would have released arsenic through hydrothermal activity, volcanic eruptions, and weathering of crustal rock. Arsenic in hydrothermal fluid would likely be rapidly precipitated by sulfides. Likewise, much of the arsenic in volcanoes would actually be deposited sub-surface as sulfides. In the presence of oxygen-rich waters, these sulfide minerals can undergo oxidative dissolution, releasing the arsenic back into the water to join that liberated by the weathering of the surface. Iron oxyhydroxides would form in such an environment, however, and these will sorb and remove arsenic from the water once again. In waters rich in organic-carbon, reducing conditions can return periodically. This would lead to reductive dissolution to liberate the arsenic from the iron oxyhydroxides. However, these conditions can also reduce sulfates to sulfides and thus reprecipitate the arsenic sulfide minerals. Furthermore, the extremely rapid formation of sedimentary rock during the Flood would likely bury both the original sulfide minerals and the arsenic-sorbed iron oxyhydroxides before they could be significantly dissolved. The modern distribution of arsenic gives evidence of this; the element is often concentrated in large sedimentary basins adjacent to orogenic belts. It appears that arsenic sulfides (formed during the Flood) were in some cases subject to uplift during orogenesis associated with the Flood and underwent oxidation, resulting in the arsenic being sorbed to iron minerals and clays. These eroded into the foreland basins and were buried before the arsenic could leach into local waters to a major degree. In modern times, however, reductive dissolutions of these deposits has resulted in arsenic poisoning. While arsenic does not threaten the Flood model (rather the Flood explains the modern distribution of arsenic), modern arsenic contamination is an ongoing result of the judgement of the Flood

Phase field theory of polycrystalline solidification in three dimensions

A phase field theory of polycrystalline solidification is presented that is able to describe the nucleation and growth of anisotropic particles with different crystallographic orientation in three dimensions. As opposed with the two-dimensional case, where a single orientation field suffices, in three dimensions, minimum three fields are needed. The free energy of grain boundaries is assumed to be proportional to the angular difference between the adjacent crystals expressed here in terms of the differences of the four symmetric Euler parameters. The equations of motion for these fields are obtained from variational principles. Illustrative calculations are performed for polycrystalline solidification with dendritic, needle and spherulitic growth morphologies.Comment: 7 pages, 4 figures, submitted to Europhysics Letters on 14th February, 200

3D atomic structure from a single XFEL pulse

X-ray Free Electron Lasers (XFEL) are the most advanced pulsed x-ray sources. Their extraordinary pulse parameters promise unique applications. Indeed, several new methods have been developed at XFEL-s. However, no methods are known, which would allow ab initio atomic level structure determination using only a single XFEL pulse. Here, we present experimental results, demonstrating the determination of the 3D atomic structure from data obtained during a single 25 fs XFEL pulse. Parallel measurement of hundreds of Bragg reflections was done by collecting Kossel line patterns of GaAs and GaP. With these measurements, we reached the ultimate temporal limit of the x-ray structure solution possible today. These measurements open the way for studying non-repeatable fast processes and structural transformations in crystals for example measuring the atomic structure of matter at extremely non-ambient conditions or transient structures formed in irreversible physical, chemical, or biological processes. It would also facilitate time resolved pump-probe structural studies making them significantly shorter than traditional serial crystallography.Comment: 16 pages of manuscript followed by 15 pages of supplementary informatio

Impact of insecticide-treated nets on wild pyrethroid resistant Anopheles epiroticus population from southern Vietnam tested in experimental huts

<p>Abstract</p> <p>Background</p> <p>In this study, the efficacy of insecticide-treated nets was evaluated in terms of deterrence, blood-feeding inhibition, induced exophily and mortality on a wild resistant population of <it>Anopheles epiroticus </it>in southern Vietnam, in order to gain insight into the operational consequences of the insecticide resistance observed in this malaria vector in the Mekong delta.</p> <p>Method</p> <p>An experimental station, based on the model of West Africa and adapted to the behaviour of the target species, was built in southern Vietnam. The study design was adapted from the WHO phase 2 guidelines. The study arms included a conventionally treated polyester net (CTN) with deltamethrin washed just before exhaustion, the WHO recommended long-lasting insecticidal net (LLIN) PermaNet 2.0^®unwashed and 20 times washed and PermaNet 3.0^®, designed for the control of pyrethroid resistant vectors, unwashed and 20 times washed.</p> <p>Results</p> <p>The nets still provided personal protection against the resistant <it>An. epiroticus </it>population. The personal protection ranged from 67% for deltamethrin CTN to 85% for unwashed PermaNet 3.0. Insecticide resistance in the <it>An. epiroticus </it>mosquitoes did not seem to alter the deterrent effect of pyrethroids. A significant higher mortality was still observed among the treatment arms despite the fact that the <it>An. epiroticus </it>population is resistant against the tested insecticides.</p> <p>Conclusion</p> <p>This study shows that CTN and LLINs still protect individuals against a pyrethroid resistant malaria vector from the Mekong region, where insecticide resistance is caused by a metabolic mechanism. In the light of a possible elimination of malaria from the Mekong region these insights in operational consequences of the insecticide resistance on control tools is of upmost importance.</p

Vibrational spectra of C60C8H8 and C70C8H8 in the rotor-stator and polymer phases

C60-C8H8 and C70-C8H8 are prototypes of rotor-stator cocrystals. We present infrared and Raman spectra of these materials and show how the rotor-stator nature is reflected in their vibrational properties. We measured the vibrational spectra of the polymer phases poly(C60C8H8) and poly(C70C8H8) resulting from a solid state reaction occurring on heating. Based on the spectra we propose a connection pattern for the fullerene in poly(C60C8H8), where the symmetry of the C60 is D2h. On illuminating the C60-C8H8 cocrystal with green or blue light a photochemical reaction was observed leading to a similar product to that of the thermal polymerization.Comment: 26 pages, 8 figures, to appear in Journal of Physical Chemistry B 2nd version: minor changes in wording, accepted version by journa

Vector control in a malaria epidemic occurring within a complex emergency situation in Burundi: a case study

BACKGROUND: African highlands often suffer of devastating malaria epidemics, sometimes in conjunction with complex emergencies, making their control even more difficult. In 2000, Burundian highlands experienced a large malaria outbreak at a time of civil unrest, constant insecurity and nutritional emergency. Because of suspected high resistance to the first and second line treatments, the provincial health authority and Médecins Sans Frontières (Belgium) decided to implement vector control activities in an attempt to curtail the epidemic. There are few reported interventions of this type to control malaria epidemics in complex emergency contexts. Here, decisions and actions taken to control this epidemic, their impact and the lessons learned from this experience are reported. CASE DESCRIPTION: Twenty nine hills (administrative areas) were selected in collaboration with the provincial health authorities for the vector control interventions combining indoor residual spraying with deltamethrin and insecticide-treated nets. Impact was evaluated by entomological and parasitological surveys. Almost all houses (99%) were sprayed and nets use varied between 48% and 63%. Anopheles indoor resting density was significantly lower in treated as compared to untreated hills, the latter taken as controls. Despite this impact on the vector, malaria prevalence was not significantly lower in treated hills except for people sleeping under a net. DISCUSSION: Indoor spraying was feasible and resulted in high coverage despite being a logistically complex intervention in the Burundian context (scattered houses and emergency situation). However, it had little impact on the prevalence of malaria infection, possibly because it was implemented after the epidemic's peak. Nevertheless, after this outbreak the Ministry of Health improved the surveillance system, changed its policy with introduction of effective drugs and implementation of vector control to prevent new malaria epidemics. CONCLUSION: In the absence of effective drugs and sufficient preparedness, present study failed to demonstrate any impact of vector control activities upon the course of a short-duration malaria epidemic. However, the experience gained lead to increased preparedness and demonstrated the feasibility of vector control measures in this specific context

Social Determinants of Long Lasting Insecticidal Hammock-Use Among the Ra-Glai Ethnic Minority in Vietnam: Implications for Forest Malaria Control

BACKGROUND: Long-lasting insecticidal hammocks (LLIHs) are being evaluated as an additional malaria prevention tool in settings where standard control strategies have a limited impact. This is the case among the Ra-glai ethnic minority communities of Ninh Thuan, one of the forested and mountainous provinces of Central Vietnam where malaria morbidity persist due to the sylvatic nature of the main malaria vector An. dirus and the dependence of the population on the forest for subsistence - as is the case for many impoverished ethnic minorities in Southeast Asia. METHODS: A social science study was carried out ancillary to a community-based cluster randomized trial on the effectiveness of LLIHs to control forest malaria. The social science research strategy consisted of a mixed methods study triangulating qualitative data from focused ethnography and quantitative data collected during a malariometric cross-sectional survey on a random sample of 2,045 study participants. RESULTS: To meet work requirements during the labor intensive malaria transmission and rainy season, Ra-glai slash and burn farmers combine living in government supported villages along the road with a second home at their fields located in the forest. LLIH use was evaluated in both locations. During daytime, LLIH use at village level was reported by 69.3% of all respondents, and in forest fields this was 73.2%. In the evening, 54.1% used the LLIHs in the villages, while at the fields this was 20.7%. At night, LLIH use was minimal, regardless of the location (village 4.4%; forest 6.4%). DISCUSSION: Despite the free distribution of insecticide-treated nets (ITNs) and LLIHs, around half the local population remains largely unprotected when sleeping in their forest plot huts. In order to tackle forest malaria more effectively, control policies should explicitly target forest fields where ethnic minority farmers are more vulnerable to malaria

The importance of considering community-level effects when selecting insecticidal malaria vector products

BACKGROUND\ud \ud Insecticide treatment of nets, curtains or walls and ceilings of houses represent the primary means for malaria prevention worldwide. Direct personal protection of individuals and households arises from deterrent and insecticidal activities which divert or kill mosquitoes before they can feed. However, at high coverage, community-level reductions of mosquito density and survival prevent more transmission exposure than the personal protection acquired by using a net or living in a sprayed house.\ud \ud METHODS\ud \ud A process-explicit simulation of malaria transmission was applied to results of 4 recent Phase II experimental hut trials comparing a new mosaic long-lasting insecticidal net (LLIN) which combines deltamethrin and piperonyl butoxide with another LLIN product by the same manufacturer relying on deltamethrin alone.\ud \ud RESULTS\ud \ud Direct estimates of mean personal protection against insecticide-resistant vectors in Vietnam, Cameroon, Burkina Faso and Benin revealed no clear advantage for combination LLINs over deltamethrin-only LLINs (P = 0.973) unless both types of nets were extensively washed (Relative mean entomologic inoculation rate (EIR) ± standard error of the mean (SEM) for users of combination nets compared to users of deltamethrin only nets = 0.853 ± 0.056, P = 0.008). However, simulations of impact at high coverage (80% use) predicted consistently better impact for the combination net across all four sites (Relative mean EIR ± SEM in communities with combination nets, compared with those using deltamethrin only nets = 0.613 ± 0.076, P < 0.001), regardless of whether the nets were washed or not (P = 0.467). Nevertheless, the degree of advantage obtained with the combination varied substantially between sites and their associated resistant vector populations.\ud \ud CONCLUSION\ud \ud Process-explicit simulations of community-level protection, parameterized using locally-relevant experimental hut studies, should be explicitly considered when choosing vector control products for large-scale epidemiological trials or public health programme procurement, particularly as growing insecticide resistance necessitates the use of multiple active ingredients