Willingness to Risk Death Endpoint in HIV Cure-Related Research with Otherwise Healthy Volunteers is Misleading

This viewpoint article critiques two recent articles examining 'willingness to risk death' to advance HIV cure-related research. The 'willingness to risk death' endpoint sends the wrong signal to the HIV cure-related research community about ongoing research in otherwise healthy volunteers living with HIV. Socio-behavioural scientists have examined the acceptability of a 99% risk of death scenario, which is unrealistic and would not be acceptable by current regulatory and ethical standards. We believe that the field needs robust and relevant socio-behavioural research reflecting ongoing biomedical HIV cure-related trials. These studies will need to withstand regulatory and ethical scrutiny if cure or remission regimens are to proceed to the licensing stage. The HIV cure-related research community must continue to protect the public trust in the HIV cure-related research field and sustain societal value generated by such research. We call for the utmost prudence in designing biomedical HIV cure trials as well as in setting up socio-behavioural research experiments related to these complex trials

Characterization and modeling of a hybrid electric vehicle lithium-ion battery pack at low temperatures

Although lithium-ion batteries have penetrated hybrid electric vehicles (HEVs) and pure electric vehicles (EVs), they suffer from significant power capability losses and reduced energy at low temperatures. To evaluate those losses and to make an efficient design, good models are required for system simulation. Subzero battery operation involves nonclassical thermal behavior. Consequently, simple electrical models are not sufficient to predict bad performance or damage to systems involving batteries at subzero temperatures. This paper presents the development of an electrical and thermal model of an HEV lithium-ion battery pack. This model has been developed with MATLAB/Simulink to investigate the output characteristics of lithium-ion batteries over the selected operating range of currents and battery capacities. In addition, a thermal modeling method has been developed for this model so that it can predict the battery core and crust temperature by including the effect of internal resistance. First, various discharge tests on one cell are carried out, and then, cell's parameters and thermal characteristics are obtained. The single-cell model proposed is shown to be accurate by analyzing the simulation data and test results. Next, real working conditions tests are performed, and simulation calculations on one cell are presented. In the end, the simulation results of a battery pack under HEV driving cycle conditions show that the characteristics of the proposed model allow a good comparison with data from an actual lithium-ion battery pack used in an HEV. © 2015 IEEE

Modeling the dynamical interaction between epidemics on overlay networks

Epidemics seldom occur as isolated phenomena. Typically, two or more viral agents spread within the same host population and may interact dynamically with each other. We present a general model where two viral agents interact via an immunity mechanism as they propagate simultaneously on two networks connecting the same set of nodes. Exploiting a correspondence between the propagation dynamics and a dynamical process performing progressive network generation, we develop an analytic approach that accurately captures the dynamical interaction between epidemics on overlay networks. The formalism allows for overlay networks with arbitrary joint degree distribution and overlap. To illustrate the versatility of our approach, we consider a hypothetical delayed intervention scenario in which an immunizing agent is disseminated in a host population to hinder the propagation of an undesirable agent (e.g. the spread of preventive information in the context of an emerging infectious disease).Comment: Accepted for publication in Phys. Rev. E. 15 pages, 7 figure

Influence of wind on crop canopy reflectance measurements

Remote sensing techniques of measuring red and far-red crop canopy reflectance are frequently used to estimate crop canopy characteristics. The variability introduced in reflectance data from nonvegetative factors such as wind decreases the usefulness of the techniques. The objective of this study was to quantify and minimize the variability from wind on spectral reflectances. Red and far-red reflectances were acquired above wheat, barley, and alfalfa canopies throughout days of changing wind conditions. Periods of 312 s with little changes in irradiance values were used for the analysis. Wind had negligible effect on reflectances of a short canopy such as cut alfalfa, while it had a significant effect on reflectances from canopies with a higher vertical structure, particularly during gusty conditions. Within the windy and calm periods, extreme values of spectral reflectance differed by 60% and 12%, respectively, in the red, and by 40% and 8% in the far-red for the barley canopy. For the compact and dense canopy structure of alfalfa, these differences reached a maximum of 10% under windy conditions in both spectral regions. The plant canopy architecture, the wind conditions, and the spectral regions all affected the magnitude of the influence of wind on crop canopy spectral reflectances. The mean reflectance of a canopy overestimated the true reflectance by 2–4% while the use of the median reduced this overestimation. Sampling requirements for this sensor are evaluated, and the possibility of decreasing either the sampling rate or the sampling period is discussed

Sun-angle effects on the red and near infrared reflectances of five different crop canopies

The objective of this paper is to study relationships between dai/y variations in sun angles and red and near infrared reflectances measured throughout a growing season over different types of crop canopies. Five architecturally different crop canopies were planted: wheat (NNW-SSE rows 0.18 m and 0.35 m apart), barley (NNW-SSE rows 0.18 m apart), corn (NNWSSE rows 0.46 m apart), and sunflower (N-S rows 0.92 m apart). Each canopy was planted at three different densifies in order to add intraspecies variability. Spectral reflectances were measured with a sensor in the nadir position located on a ground platform. Changes in sun angles usually affected the red more than near infrared reflectances. Within each crop, the canopies with the lowest LAI a/ways showed the larges! variations in spectral reflectances. But among the crops, the importance of changing sun angles on crop canopy reflectances varied with the architecture of the canopy. Red reflectances collected over corn and sunflower at LAI of 6 were insensitive to changes in sun angles, while those collected above sunflower showed significant differences when LAI was around 4. The higher proportion of horizontal foliar area compared to the vertical one in corn canopies could account for this difference between the two crops, since a canopy with horizontal foliar distribution is a nearer approximation of a lambertian surface. The differences in row width and orientation could also explain some of these differences. Reflectances of wheat canopies planted with rows 0.35 m apart showed larger red reflectance variations within a day than those planted 0.17 m apart. The maximum red reflectances always appeared when the sun was in fine with row direction. The fact that most rapid variations in red reflectances were occurring around this particular time of the day also confirmed that there is a strong interaction between row direction and width with the position of the sun in the sky. The magnitude of the effect of the variations of sun angles on crop canopy spectral reflectances was shown to be dependent on the species, planting patterns, wavelength band, and sky conditions. Le présent article décrit une étude des relations entre les variations quotidiennes de l'angle du soleil ainsi que des réflectances dans le rouge et le proche infrarouge mesurées tout au long d'une saison de récolte sur différents types de couverts végétaux. Cinq couverts végétaux de structure différente ont été semés: blé (rangs NNO-SSE à intervalles de 0,18 et 0,35 mètres), orge (rangs NNO-SSE à intervalles de 0,18 mètre), maïs (rangs NNO-SSE à intervalles de 0,46 mètre) et tournesol (rangs N-S à intervalles de 0,92 mètre). Chaque couvert végétal a été semé à trois densités différentes de manière à pouvoir mesurer la variabilité au sein de chaque espèce. Les réflectances spectrales ont été mesurées à la position nadir à l'aide d'un capteur fixé à une plate-forme au sol. En général, les variations de l'angle du soleil touchaient davantage les réflectances dans le rouge que les réflectances dans le proche infrarouge. Pour chaque culture, les couverts ayant l'indice de surface foliaire (ISF) le moins élevé ont systématiquement donné la plus grande variation au niveau des réflectances spectrales. Par contre, entre les diverses cultures, la variation de l'angle du soleil sur les réflectances des couverts végétaux était fonction de la structure du couvert. Les réflectances rouges recueillies au-dessus du maïs et du tournesol avec un ISF de 6 étaient insensibles aux variations de l'angle du soleil, tandis que celles mesurées au-dessus des tournesols variaient substantiellement lorsque l'ISF était aux environs de 4. Cette différence entre les deux cultures peut s'expliquer par la présence d'une plus grande distribution foliaire horizontale comparativement à la surface verticale offerte par le couvert de maïs, puisqu'un couvert ayant une distribution foliaire horizontale se rapproche davantage d'une surface lambertienne. La différence dans la largeur et l'orientation des rangs pourrait aussi expliquer certaines de ces différences. Les couverts de blé semés en rangs à intervalles de 0,35 mètre ont donné des variations de réflectances dans le rouge plus grandes dans une journée que ceux semés à intervalles de 0,17 mètre. Les réflectances maximales dans le rouge se produisaient toujours lorsque le soleil était en ligne avec les rangs. Le fait que la plupart des variations rapides des réflectances dans le rouge se produisaient à ce moment particulier de la journée a aussi confirmé qu'il existe une forte corrélation entre la direction et la largeur des rangs et la position du soleil dans le ciel. Cette étude a démontré que l'ampleur de l'incidence des variations de l'angle du soleil sur les réflectances spectrales des couverts végétaux est fonction de l'espèce, du mode de semence, de la longueur d'ondes de la bande et des conditions du ciel

Lithium-ion battery aging experiments at subzero temperatures and model development for capacity fade estimation

Lithium-ion (Li-ion) batteries widely used in electric vehicles (EVs) and hybrid EVs (HEVs) are insufficient for vehicle use after they have degraded to 70% to 80% of their original capacity. Battery lifespan is a large consideration when designing battery packs for EVs/HEVs. Aging mechanisms, such as metal dissolution, growth of the passivated surface film layer on the electrodes, and loss of both recyclable lithium ions, affect the longevity of the Li-ion battery at higherature operations. Even vehicle maneuvers at low temperatures (T<0°C)contribute to battery lifetime degradation, owing to the anode electrode vulnerability to other degradation mechanisms such as lithium plating. Nowadays, only a few battery thermal management schemes have properly considered lowerature degradation. This is due to the lack of studies on aging of Li-ion batteries at sub-zero temperature. This paper investigates how load cycle and calendar life properties affect the lifetime and aging processes of Li-ion cells at low temperatures. Accelerated aging tests were used to determine the effect of the ambient temperature on the performance of three 100-Ah LiFeMnP04 Li-ion cells. Two of them were aged through a normalized driving cycle at two temperature tests (-20°C and 25°C). The calendar test was carried out on one single battery at -20 °C and mid-range of state of charge (50%). Their capacities were continuously measured every two or three days. An aging model is developed and added to a preliminary single-cell electrothermal model to establish, in future works, a thermal strategy capable of predicting how the cell ages. This aging model was then validated by comparing its predictions with the aging data obtained from a cycling test at 0 °C. © 1967-2012 IEEE

Interface Equations for Capillary Rise in Random Environment

We consider the influence of quenched noise upon interface dynamics in 2D and 3D capillary rise with rough walls by using phase-field approach, where the local conservation of mass in the bulk is explicitly included. In the 2D case the disorder is assumed to be in the effective mobility coefficient, while in the 3D case we explicitly consider the influence of locally fluctuating geometry along a solid wall using a generalized curvilinear coordinate transformation. To obtain the equations of motion for meniscus and contact lines, we develop a systematic projection formalism which allows inclusion of disorder. Using this formalism, we derive linearized equations of motion for the meniscus and contact line variables, which become local in the Fourier space representation. These dispersion relations contain effective noise that is linearly proportional to the velocity. The deterministic parts of our dispersion relations agree with results obtained from other similar studies in the proper limits. However, the forms of the noise terms derived here are quantitatively different from the other studies