Macromorphology and recruitment of Prosopis cineraria in the United Arab Emirates

Recruitment frequency of Prosopis cinerarium the United Arab Emirates is poorly understood, though heavy browsing by camels is often assumed to be a limiting factor. Macromorphological characteristics were recorded at eight locations from the northern United Arab Emirates. Tree size (canopy diameter, trunk diameter, and tree height) showed conformity within locations. Height of browse line was strongly affected by camels, which removed foliage to a height of 3 meters whenever present. Recruitment by seed was not observed during the study, and observed asexual recruitment was limited to root suckers produced only within the season. Presence of suckers was unrelated to browsing but strongly affected by a shifting ground surface. Viable theories for the absence of sexual recruitment include seedling destruction by herbivores, a lack of safe sites for seedling growth and establishment, and that sexual recruitment events might naturally occur rarely, but produce many recruits in the rare successful seasons. Significant recruitment of new individuals is likely to occur only with protection from current herbivory systems

Characterization of the indoor kitchen soundscape

With a growing tendency for compact living, the kitchen space is typically at the center of the daily activity, combining different functionalities. In the context of the ”IoT chef” project, the cooking experience is optimized, with focus on the cooker hood noise. In a first part of the study, a large-scale online survey (N = 754) is conducted among Flemish home cooks in order to (1) map personal assessments of the sound environment during a typical cooking experience and (2) evaluate the indoor (kitchen) soundscape based on the ISO 12913-1/2 standard. The impact of the role of the observant (chef or bystander) on the subjective evaluation is investigated. In a second part of the study, typical kitchen sound levels are monitored during a one-week period at 16 households, selected from survey participants. Additionally, cooker hood levels are measured at the cook’s ears to define the contribution of hood noises in the overall kitchen soundenvironment. Results from the measurement campaign are presented and discussed

Divergence, recombination and retention of functionality during protein evolution

We have only a vague idea of precisely how protein sequences evolve in the context of protein structure and function. This is primarily because structural and functional contexts are not easily predictable from the primary sequence, and evaluating patterns of evolution at individual residue positions is also difficult. As a result of increasing biodiversity in genomics studies, progress is being made in detecting context-dependent variation in substitution processes, but it remains unclear exactly what context-dependent patterns we should be looking for. To address this, we have been simulating protein evolution in the context of structure and function using lattice models of proteins and ligands (or substrates). These simulations include thermodynamic features of protein stability and population dynamics. We refer to this approach as ‘ab initio evolution ’ to emphasise the fact that the equilibrium details of fitness distributions arise from the physical principles of the system and not from any preconceived notions or arbitrary mathematical distributions. Here, we present results on the retention of functionality in homologous recombinants following population divergence. A central result is that protein structure charac-teristics can strongly influence recombinant functionality. Exceptional structures with many sequence options evolve quickly and tend to retain functionality — even in highly diverged recombinants. By contrast, the more common structures with fewer sequence options evolve more slowly, but the fitness of recombinants drops off rapidly as homologous proteins diverge. These results have implications fo

Tunable magnetic exchange interactions in manganese-doped inverted core/shell ZnSe/CdSe nanocrystals

Magnetic doping of semiconductor nanostructures is actively pursued for applications in magnetic memory and spin-based electronics. Central to these efforts is a drive to control the interaction strength between carriers (electrons and holes) and the embedded magnetic atoms. In this respect, colloidal nanocrystal heterostructures provide great flexibility via growth-controlled `engineering' of electron and hole wavefunctions within individual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d exchange interaction between electron-hole excitations (excitons) and paramagnetic manganese ions using `inverted' core-shell nanocrystals composed of Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe. Magnetic circular dichroism studies reveal giant Zeeman spin splittings of the band-edge exciton that, surprisingly, are tunable in both magnitude and sign. Effective exciton g-factors are controllably tuned from -200 to +30 solely by increasing the CdSe shell thickness, demonstrating that strong quantum confinement and wavefunction engineering in heterostructured nanocrystal materials can be utilized to manipulate carrier-Mn wavefunction overlap and the sp-d exchange parameters themselves.Comment: To appear in Nature Materials; 18 pages, 4 figures + Supp. Inf

Strong armies, slow adaptation: civil-military relations and diffusion of military power

Why are some states more willing to adopt military innovations than others? Why, for example, were the great powers of Europe able to successfully reform their military practices to better adapt to and participate in the so-called military revolution of the sixteenth and seventeenth centuries while their most important extra-European competitor, the Ottoman Empire, failed to do so? This puzzle is best explained by two factors: civil-military relations and historical timing. In the Ottoman Empire, the emergence of an institutionally strong and internally cohesive army during the early stages of state formation—in the late fourteenth century—equipped the military with substantial bargaining powers. In contrast, the great powers of Europe drew heavily on private providers of military power during the military revolution and developed similar armies only by the second half of the seventeenth century, limiting the bargaining leverage of European militaries over their rulers. In essence, the Ottoman standing army was able to block reform efforts that it believed challenged its parochial interests. Absent a similar institutional challenge, European rulers initiated military reforms and motivated officers and military entrepreneurs to participate in the ongoing military revolution

Shale disposal of U.S. high-level radioactive waste.

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