Two-temperature pair potentials and phonon spectra for simple metals in the warm dense matter regime

We develop ion-ion pair potentials for Al, Na and K for densities and temperatures relevant to the warm-dense-matter (WDM) regime. Furthermore, we emphasize non-equilibrium states where the ion temperature $T_i$ differs from the electron temperature $T_e$. This work focuses mainly on ultra-fast laser-metal interactions where the energy of the laser is almost exclusively transferred to the electron sub-system over femtosecond time scales. This results in a two-temperature system with $T_e>T_i$ and with the ions still at the initial room temperature $T_i=T_r$. First-principles calculations, such as density functional theory (DFT) or quantum Monte Carlo, are as yet not fully feasible for WDM conditions due to lack of finite-$T$ features, e.g. pseudopotentials, and extensive CPU time requirements. Simpler methods are needed to study these highly complex systems. We propose to use two-temperature pair potentials $U_{ii}(r, T_i,T_e)$ constructed from linear-response theory using the non-linear electron density $n(\mathbf{r})$ obtained from finite-$T$ DFT with a single ion immersed in the appropriate electron fluid. We compute equilibrium phonon spectra at $T_r$ which are found to be in very good agreement with experiments. This gives credibility to our non-equilibrium phonon dispersion relations which are important in determining thermophysical properties, stability, energy-relaxation mechanisms and transport coefficients.Comment: International Conf. on Strongly-Coupled Coulombo Systems (SCCS) 201

Modification and analysis of proteins involved in gliding motility and invasion of Plasmodium

Motility is an important feature of cells that is required for the development of multicellular organisms (Trepat et al. 2012), to heal tissue and fight invading pathogens. But also pathogens itself depend on motility to migrate through tissue barriers and infect hosts. Especially parasites of the genus Plasmodium that are the causative agents of malaria in humans require active movement in order to complete their life cycles. Motility of these parasites is not dependent on alterations of their cell shape, as it is usually observed in mammalian cells, and is therefore called gliding motility. While the mechanism of gliding motility is still not fully understood it is known that specific surface proteins called adhesins are essential for the parasite to perform active movement. In order to better understand the function of adhesins in gliding motility this thesis investigates sporozoite-specific adhesins by using genetic approaches like gene knockout, mutation of single amino acids as well as deletion or exchange of whole domains. A particular focus is put on the thrombospondin related anonymous protein (TRAP) that is specifically expressed at the sporozoite stage. Previous research showed that the deletion of TRAP abrogates directed movement of sporozoites as well as the invasion of the salivary glands of the mosquito. In addition sporozoites lacking TRAP are not infectious to mice if intravenously injected (Sultan et al. 1997). However, while the functions of TRAP are well characterised the mode of action of TRAP is still unknown. To gain further insight into the functions of this adhesin this thesis investigates the Von Willebrandt factor like A-domain as well as the thrombospondin type-I repeat in TRAP ́s extracellular portion and their implications in gliding motility and invasion of sporozoites. To analyse the phenotype of transgenic sporozoites in vitro and in vivo the rodent malaria parasite Plasmodium berghei was used. Utilizing this strategy it is possible to investigate the transmission potential of generated parasite lines by infecting mice via intravenous injection of sporozoites or via bites of infected mosquitos which are experiments that are difficult to perform with the human malaria parasite Plasmodium falciparum. Taken together this thesis aims to gain more insight into ligand recognition by TRAP and Plasmodium transmission in general

Doming Modes and Dynamics of Model Heme Compounds

Synchrotron far-IR spectroscopy and density-functional calculations are used to characterize the low-frequency dynamics of model heme FeCO compounds. The “doming” vibrational mode in which the iron atom moves out of the porphyrin plane while the periphery of this ring moves in the opposite direction determines the reactivity of oxygen with this type of molecule in biological systems. Calculations of frequencies and absorption intensities and the measured pressure dependence of vibrational modes in the model compounds are used to identify the doming and related normal modes

Acceptable Noise Levels for Typical Outdoor Leisure Activities

Throughout the Appalachian Mountain chain, entrepreneurs have capitalized on the outdoor sporting experience.  Both summer and winter sports such as fly fishing, hiking, skiing and snowboarding are very popular. One popular emerging activity is skeet, trap, and sporting clays shooting.  Major tourist enterprises are developing this opportunity for both tourists and the local residents.  To meet the increasing demand, ranges are being constructed throughout the region from Alabama to Maine.  Within North Carolina that are approximately 12 ranges, with an additional 10 in east Tennessee. Although these activities have had few opponents, sporting clays establishments have received an insignificant number of complaints that the noise level is above the noxious level.  A research experiment was designed to test noise levels at one sporting clays course situated near a vacation resort. The first phase of this experiment determined that the noise levels at the source from 12 and 20 gauge shotguns were insignificant. The allowable rounds used are the standard reduced load target load. At the source there was a significant difference between trap (85.85 dBA) and skeet (74.95 dBA). At the closest guest location (second phase) 333 samples were taken between August 2015 and March 2016.  The noise level averaged 53.7 dBA (σ = 7.43dBA). During the third phase (January to March 2016) 44 samples were obtained at the main resort lodging site.  At Site 2 the noise level averaged 31.9 dBA (σ = 5.45).  The fourth and final phase of this study was to determine the noise levels at the closest guest location for each of the 12 sporting clays stations.  Ninety-six samples (8 per station) were collected in October 2016. The average noise level was 53.0 dBA (σ 4.19 dBA). An analysis at the statistical confidence level of 97.5% was conducted.  First all stations were analyzed in a pairwise comparison analysis.  Stations that were not significantly different from one another were combined.  Thus the 12 stations were reduced to three combined stations.  The analysis determined that the noise level from stations 1 through 5 (48.9dBA, σ =1.50 dBA) was significantly lower than from the other stations.  Next loudest was the combinations of stations 6, 7, 10, and 11 (54.1 dBA, σ = 1.69). The last loudest combination was stations 8, 9, and 12 (58.6 dBA, σ = 1.50 dDA).  Thus there was a difference of 9.7 dBA between the lowest and the loudest station.  Since every 5 dBA difference equates to 2 to 3 times louder, depending on frequency, the loudest station is approximately 4 to 6 times louder that the lowest noise level.  However, all stations are below the OSHA Standard.  With an annoyance level (60.0 dBA) for the guest activity, the gunshots are less than the nuisance level and significantly less than the permissible level. The few complaints about the noise levels are not supported by the noise level data. A logical conclusion is that the objection is the act of shooting and not the noise level of the shotgun’s sharp or impact report. Potential solutions might be to examine stations 8, 9, and 12 and considering possible relocation, orientation, or emplacement of a thick tree barrier to absorb the reports. Regression analysis was used to develop a highly significant model to predict noise levels with the variables collected. However, this will not solve the complaints from those who object to reports under any circumstance

Evolutionarily distant I domains can functionally replace the essential ligand-binding domain of Plasmodium TRAP

Inserted (I) domains function as ligand-binding domains in adhesins that support cell adhesion and migration in many eukaryotic phyla. These adhesins include integrin alpha beta heterodimers in metazoans and single subunit transmembrane proteins in apicomplexans such as TRAP in Plasmodium and MIC2 in Toxoplasma. Here we show that the I domain of TRAP is essential for sporozoite gliding motility, mosquito salivary gland invasion and mouse infection. Its replacement with the I domain from Toxoplasma MIC2 fully restores tissue invasion and parasite transmission, while replacement with the aXI domain from human integrins still partially restores liver infection. Mutations around the ligand binding site allowed salivary gland invasion but led to inefficient transmission to the rodent host. These results suggest that apicomplexan parasites appropriated polyspecific I domains in part for their ability to engage with multiple ligands and to provide traction for emigration into diverse organs in distant phyla

Using coherent phonons for ultrafast control of the Dirac node of SrMnSb\u3csub\u3e2\u3c/sub\u3e

SrMnSb2 is a candidate Dirac semimetal whose electrons near the Y point have the linear dispersion and low mass of a Dirac cone. Here we demonstrate that ultrafast, 800-nm optical pulses can launch coherent phonon oscillations in Sr0.94Mn0.92Sb2, particularly an Ag mode at 4.4 THz. Through first-principles calculations of the electronic and phononic structure of SrMnSb2, we show that high-amplitude oscillations of this mode would displace the atoms in a way that transiently opens and closes a gap at the node of the Dirac cone. The ability to control the nodal gap on a subpicosecond timescale could create opportunities for the design and manipulation of Dirac fermions