Optimum sterilization: a comparative study between average and surface quality

Sterilization temperatures to maximize volume average or surface quality retention were calculated for one-dimensional conduction heating foods as a function of (1) Food Properties, (2) Processing Conditions and (3) Processing Criteria. A target lethality at the least-lethality point was used as a constraint, and optimal temperatures were qualitatively and quantitatively compared for equal design variables. Average quality optimum conditions depend linearly on the inverse square of the Drefq-value for the quality factor. These conditions do not vary linearly with all the other influential variables, opposite to what had been observed for surface quality. Optimum temperature for maximum average quality is always higher than the corresponding one for surface quality, but the difference is not constant. A systematic approach to the dependence of average quality optimal conditions on all the relevant parameters was carried out and quantitative relations were obtained. Optimum average quality retention is independent of surface heat transfer resistance

Low disordered, stable, and shallow germanium quantum wells: a playground for spin and hybrid quantum technology

Buried-channel semiconductor heterostructures are an archetype material platform to fabricate gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface, however nearby surface states degrade the electrical properties of the starting material. In this paper we demonstrate a two-dimensional hole gas of high mobility ($5\times 10^{5}$ cm$^2$/Vs) in a very shallow strained germanium channel, which is located only 22 nm below the surface. This high mobility leads to mean free paths $\approx6 \mu m$, setting new benchmarks for holes in shallow FET devices. Carriers are confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The top-gate of a dopant-less field effect transistor controls the carrier density in the channel. The high mobility, along with a percolation density of $1.2\times 10^{11}\text{ cm}^{-2}$, light effective mass (0.09 m$_e$), and high g-factor (up to $7$) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies

Low-rank multi-parametric covariance identification

We propose a differential geometric construction for families of low-rank covariance matrices, via interpolation on low-rank matrix manifolds. In contrast with standard parametric covariance classes, these families offer significant flexibility for problem-specific tailoring via the choice of "anchor" matrices for the interpolation. Moreover, their low-rank facilitates computational tractability in high dimensions and with limited data. We employ these covariance families for both interpolation and identification, where the latter problem comprises selecting the most representative member of the covariance family given a data set. In this setting, standard procedures such as maximum likelihood estimation are nontrivial because the covariance family is rank-deficient; we resolve this issue by casting the identification problem as distance minimization. We demonstrate the power of these differential geometric families for interpolation and identification in a practical application: wind field covariance approximation for unmanned aerial vehicle navigation

Advancing the remote sensing of precipitation

Satellite-based global precipitation data has addressed the limitations of rain gauges and weather radar systems in forecasting applications and for weather and climate studies. Inspite of this ability, a number of issues that require the development of advanced concepts to address key challenges in satellite-based observations of precipitation were identified during the Advanced Concepts Workshop on Remote Sensing of Precipitation at Multiple Scales at the University of California. These include quantification of uncertainties of individual sensors and their propagation into multisensor products warrants a great deal of research. The development of metrics for validation and uncertainty analysis are of great importance. Bias removal, particularly probability distribution function (PDF)-based adjustment, deserves more in-depth research. Development of a near-real-time probabilistic uncertainty model for satellitebased precipitation estimates is highly desirable

Niche complementarity and facilitation drive positive diversity effects on biomass production in experimental benthic diatom biofilms

Up to now, relatively few diversity-production experiments have been performed using microorganisms. Benthic diatom communities from estuarine intertidal mudflats are especially interesting for this purpose as they are relatively species poor and are thus more easy to simulate in laboratory conditions. We studied the effect of diversity on biomass production during microcosm experiments with diatoms assembled in combinations of up to eight species. Our results demonstrate a highly positive effect of biodiversity on production, with transgressive overyielding occurring in more than half of the combinations. These strong positive diversity effects could largely be attributed to positive complementarity effects (covering both niche complementarity and facilitation), although negative selection effects effects at higher diversities. We found a significant positive relation between functional diversity and the net biodiversity effects, indicating niche complementarity. In addition, we provide one of the first mechanistic evidences for facilitation by which biodiversity can enhance ecosystem functioning. This was demonstrated by the improved growth of Cylindrotheca closterium after addition of spent medium obtained from other diatom species. The stimulated growth of C. closterium was explained by a shift to mixotrophic growth with a down-regulation of the photosynthetic apparatus

Preventing <i>Staphylococcus aureus</i> Sepsis through the Inhibition of Its Agglutination in Blood

Staphylococcus aureus infection is a frequent cause of sepsis in humans, a disease associated with high mortality and without specific intervention. When suspended in human or animal plasma, staphylococci are known to agglutinate, however the bacterial factors responsible for agglutination and their possible contribution to disease pathogenesis have not yet been revealed. Using a mouse model for S. aureus sepsis, we report here that staphylococcal agglutination in blood was associated with a lethal outcome of this disease. Three secreted products of staphylococci - coagulase (Coa), von Willebrand factor binding protein (vWbp) and clumping factor (ClfA) – were required for agglutination. Coa and vWbp activate prothrombin to cleave fibrinogen, whereas ClfA allowed staphylococci to associate with the resulting fibrin cables. All three virulence genes promoted the formation of thromboembolic lesions in heart tissues. S. aureus agglutination could be disrupted and the lethal outcome of sepsis could be prevented by combining dabigatran-etexilate treatment, which blocked Coa and vWbp activity, with antibodies specific for ClfA. Together these results suggest that the combined administration of direct thrombin inhibitors and ClfA-antibodies that block S. aureus agglutination with fibrin may be useful for the prevention of staphylococcal sepsis in humans.</p

Ballistic supercurrent discretization and micrometer-long Josephson coupling in germanium

We fabricate Josephson field-effect-transistors in germanium quantum wells contacted by superconducting aluminum and demonstrate supercurrents carried by holes that extend over junction lengths of several micrometers. In superconducting quantum point contacts we observe discretization of supercurrent, as well as Fabry-Perot resonances, demonstrating ballistic transport. The magnetic field dependence of the supercurrent follows a clear Fraunhofer-like pattern and Shapiro steps appear upon microwave irradiation. Multiple Andreev reflections give rise to conductance enhancement and evidence a transparent interface, confirmed by analyzing the excess current. These demonstrations of ballistic superconducting transport are promising for hybrid quantum technology in germanium