Optimal control of magnetization dynamics in ferromagnetic heterostructures by spin--polarized currents

We study the switching-process of the magnetization in a ferromagnetic-normal-metal multilayer system by a spin polarized electrical current via the spin transfer torque. We use a spin drift-diffusion equation (SDDE) and the Landau-Lifshitz-Gilbert equation (LLGE) to capture the coupled dynamics of the spin density and the magnetization dynamic of the heterostructure. Deriving a fully analytic solution of the stationary SDDE we obtain an accurate, robust, and fast self-consistent model for the spin-distribution and spin transfer torque inside general ferromagnetic/normal metal heterostructures. Using optimal control theory we explore the switching and back-switching process of the analyzer magnetization in a seven-layer system. Starting from a Gaussian, we identify a unified current pulse profile which accomplishes both processes within a specified switching time.Comment: 5 figure

Spiranthes vernalis Engelm. & A. Gray

https://thekeep.eiu.edu/herbarium_specimens_byname/21408/thumbnail.jp

Irreversibilitaet der aeroben Spaltkraft bei optimaler Sauerstoffversorgung der Zelle

Mit der Entdeckung der Krebsglykolyse durch Warburg sind zwei differente Arten von Spaltungsstoffwechsel bekannt geworden. Die aerob irreversible Spaltkraft ist nach Warburg fuer alle malignen Zellen symptomatisch. Aber auch die Hefen und Milchsaeurebakterien in der Natur verfuegen, wie im folgenden nachgewiesen wird, ueber die Faehigkeit der aeroben Zuckerspaltung. Die gaerfaehige Torulopsis, von Meyerhof als Prototyp der aerob nicht-gaerenden Hefen herausgestellt, bildet oxy- wie anoxybiotisch annaehernd die gleichen Mengen Alkohol. Bei der zymagenen Umzuechtung von urspruenglich nur atmenden Torulazeen ist die Spaltkraft bereits in statu nascendi aerob irreversibel konstituiert. Die Meyerhofsche Korrelationstheorie von der aeroben Dominanz der Atmung ueber die Spaltung ist demnach in ihrem unitarischen Anspruch unsubstantiiert und zu reduzieren. Die Hefezelle, die im ausgereiften, ruhenden Zustand keiner O(2)-Beeinflussung unterliegt, ist vegetativ O(2)-abhaengig, sowohl in bezug auf die Proliferation selbst, als auch hinsichtlich der potentiellen Ausbildung der Stoffwechselkraefte. Im vegetativen Stadium tritt die Pasteursche "consequence de la vie sans air" voll in Erscheinung. Fuer die fertig ausgebildete, nicht in Vermehrung befindliche Hefezelle gibt es indessen weder eine Pasteursche Konsequenz der Anaerobiose, noch eine Meyerhofsche Korrelation zwischen Oxy- und Anoxybiose

The Portuguese S3-Non-invasive Ventilation (S3-NIV) questionnaire for home mechanically ventilated patients

Short, valid and easy to use tools are needed to monitor home mechanical ventilation (HMV) in clinical practice and for organization of HMV services. The S3NIV is a self-administered questionnaire containing 11 items that includes a Respiratory Symptoms and Sleep & Side Effects subscores, ranging from 0 (highest impact of disease and treatment) to 10 (lowest impact of disease and treatment). The Portuguese version of the questionnaire was obtained using translation-back translation process with two professional translators and it was then validated on 234 stable patients (128 male patients, 53.8%) with a mean age of 69.3 (SD 11.0) years under long-term home non-invasive ventilation. Data on total score and subscales according to disease category are reported on the table. Internal consistency for the total score was good (Cronbach’s α coefficient of 0.76) as well as for the Respiratory Symptoms and the Sleep & Side effects domains (Cronbach’s α coefficient=0.68 and Cronbach’s α coefficient=0.72, respectively). The Portuguese version of the S3-NIV questionnaire is a simple and valid tool for the routine clinical assessment of patients receiving HMV. Although they have advanced diseases, it appears patients recognize treatment benefits and have controlled side effects

Thermodynamically Stable One-Component Metallic Quasicrystals

Classical density-functional theory is employed to study finite-temperature trends in the relative stabilities of one-component quasicrystals interacting via effective metallic pair potentials derived from pseudopotential theory. Comparing the free energies of several periodic crystals and rational approximant models of quasicrystals over a range of pseudopotential parameters, thermodynamically stable quasicrystals are predicted for parameters approaching the limits of mechanical stability of the crystalline structures. The results support and significantly extend conclusions of previous ground-state lattice-sum studies.Comment: REVTeX, 13 pages + 2 figures, to appear, Europhys. Let

Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies

The binding energies of 29Si, 33S, and 36Cl have been measured with a relative uncertainty $< 0.59 \times 10^{-6}$ using a flat-crystal spectrometer. The unique features of these measurements are 1) nearly perfect crystals whose lattice spacing is known in meters, 2) a highly precise angle scale that is derived from first principles, and 3) a gamma-ray measurement facility that is coupled to a high flux reactor with near-core source capability. The binding energy is obtained by measuring all gamma-rays in a cascade scheme connecting the capture and ground states. The measurements require the extension of precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region, a significant precision measurement challenge. The binding energies determined from these gamma-ray measurements are consistent with recent highly accurate atomic mass measurements within a relative uncertainty of $4.3 \times 10^{-7}$. The gamma-ray measurement uncertainties are the dominant contributors to the uncertainty of this consistency test. The measured gamma-ray energies are in agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure

A performance comparison of the contiguous allocation strategies in 3D mesh connected multicomputers

The performance of contiguous allocation strategies can be significantly affected by the distribution of job execution times. In this paper, the performance of the existing contiguous allocation strategies for 3D mesh multicomputers is re-visited in the context of heavy-tailed distributions (e.g., a Bounded Pareto distribution). The strategies are evaluated and compared using simulation experiments for both First-Come-First-Served (FCFS) and Shortest-Service-Demand (SSD) scheduling strategies under a variety of system loads and system sizes. The results show that the performance of the allocation strategies degrades considerably when job execution times follow a heavy-tailed distribution. Moreover, SSD copes much better than FCFS scheduling strategy in the presence of heavy-tailed job execution times. The results also show that the strategies that depend on a list of allocated sub-meshes for both allocation and deallocation have lower allocation overhead and deliver good system performance in terms of average turnaround time and mean system utilization

Patients' perspective and lung function correlation:the importance of questionnaires in home mechanical ventilation

Classical physiological variables used to monitor respiratory function in patients under non-invasive ventilation (NIV), such as FEV1 or FVC, correlate poorly with reported impairment of physical function or overall health status and hence provide an incomplete picture of impaired health. Aim: to investigate the association between the Portuguese S3-non-invasive ventilation (S3-NIV) questionnaire score and objective measures of lung function. Consecutive adult patients with chronic respiratory failure, established on home NIV for at least 30 days were recruited in one outpatient clinic. Correlations between physiological variables and S3-NIV score were computed with Spearman rank coefficient. We studied 230 stable patients (126 male, 54.8%) with a mean age of 69.2 (± 11,0) years. Demographic and spirometry characteristics, and S3-NIV respiratory and total scores are presented on the table, according to disease groups. Spearman coefficient values are also presented. Neither the S3-NIV total score nor the respiratory symptoms subscore correlate with lung function impairment in any of the disease groups. This reinforces the notion that symptoms questionnaires and patient reported outcome measures must always be obtained directly from the patient and should be included in regular treatment monitoring

Transition-metal interactions in aluminum-rich intermetallics

The extension of the first-principles generalized pseudopotential theory (GPT) to transition-metal (TM) aluminides produces pair and many-body interactions that allow efficient calculations of total energies. In aluminum-rich systems treated at the pair-potential level, one practical limitation is a transition-metal over-binding that creates an unrealistic TM-TM attraction at short separations in the absence of balancing many-body contributions. Even with this limitation, the GPT pair potentials have been used effectively in total-energy calculations for Al-TM systems with TM atoms at separations greater than 4 AA. An additional potential term may be added for systems with shorter TM atom separations, formally folding repulsive contributions of the three- and higher-body interactions into the pair potentials, resulting in structure-dependent TM-TM potentials. Towards this end, we have performed numerical ab-initio total-energy calculations using VASP (Vienna Ab Initio Simulation Package) for an Al-Co-Ni compound in a particular quasicrystalline approximant structure. The results allow us to fit a short-ranged, many-body correction of the form a(r_0/r)^{b} to the GPT pair potentials for Co-Co, Co-Ni, and Ni-Ni interactions.Comment: 18 pages, 5 figures, submitted to PR

Challenges for the balanced attribution of livestock’s environmental impacts: the art of conveying simple messages around complex realities

Meat production is often listed among the largest contributors to climate change, and is usually associated with biodiversity damage, feed-food competition, and water scarcity. This assumption is largely based on the biogenic methane (CH4) emissions of the global herd of ruminants and its occupation of land. Environmental assessments of the livestock sector are all too frequently stated in simplistic terms, making use of a myopic selection of metrics, and overlooking underlying heterogeneity and complexities. One example of such oversimplification is the comparison of the warming effect of different greenhouse gases (CO2, CH4, and N2O), which are associated with a series of challenges due to their own heterogeneous atmospheric ‘behavior’. Whilst useful for certain research questions, standardizations such as the commonly used GWP100 hide many complex issues. These issues include considering different emission profiles of production systems (e.g., low-methane porcine vs. high-methane ruminant), the need to factor in CO2 and CH4 sinks, the different atmospheric lifetimes of each gas and subsequent atmospheric warming potential, and compensatory background emissions in alternative rewilding scenarios. Whilst poorly managed land negatively affects biodiversity, well-managed land strategies, including those pertaining to livestock production, can lead to favorable outcomes (e.g., biodiverse swards that encourage pollination and beneficial microfauna). Similarly, the assessment of water wastage and land use requires contextualized approaches. This highlights the importance of addressing agricultural heterogeneity in systems analysis, including Life Cycle Assessment (LCA). To further reflect the food-environment nexus, nutritional LCA (nLCA) incorporates considerations of food. optimizing e.g. nutritional sustenance and reducing, in theory, the amount of food we consume through meal-level assessment - rather than focusing on a single product.• Being more recent than the wider LCA ‘umbrella’ (e.g., Life Cycle Cost Analyses), one current drawback of nLCA is that it can be easily manipulated to favour one product over another, whether plant- or animal sourced, by singling out specific nutrients (e.g., fiber or vitamin C vs. vitamin B12 or digestible amino acid balanced protein). When considering the value of livestock products against their environmental impact, a holistic assessment is needed using balanced metrics and avoiding tunnel vision. Besides factoring in nutrition and co-product benefits, other natural capitals, and societal assets that result from well-managed farm enterprises need to be acknowledged, even if no empirical metric can currently fully account for their true value. Examples include: biodiversity, soil health, land stewardship, and rural community support; especially in a time of extreme variability due to climate, social unrest, and economic crises