A hybrid multilevel converter for medium and high voltage applications

This paper investigates the suitability of the hybrid multilevel converter for medium and high voltage application. The converter operation, modulation, and capacitor voltage balancing method are described in detail. The ability of the hybrid multilevel converter to operate with different modulation indices and load power factors is investigated. It has been established that the hybrid multilevel converter is capable of operating independent of load power factor. Operation with variable modulation index increases voltage stresses on the converter switches and does not alter the fundamental voltage magnitude as in all known voltage source converter topologies. The viability of the hybrid multilevel converter for medium and high voltage applications is confirmed by simulations

Effects of heat and drought on carbon and water dynamics in a regenerating semi-arid pine forest: a combined experimental and modeling approach

Predicting the net effects on the carbon and water balance of semi-arid forests under future conditions depends on ecosystem processes responding to changes in soil and atmospheric drought. Here we apply a combination of field observations and soil-plant-atmosphere modeling (SPA) to study carbon and water dynamics in a regenerating ponderosa pine forest. The effects of soil and atmospheric drought were quantified based on a field irrigation experiment combined with model simulations. To assess future effects of intensifying drought on ecosystem processes, the SPA model was run using temperature and precipitation scenarios for 2040 and 2080. Experimentally increased summer water availability clearly affected tree hydraulics and enhanced C uptake in both the observations and the model. Simulation results showed that irrigation was sufficient to eliminate soil water limitation and maintaining transpiration rates, but gross primary productivity (GPP) continued to decrease. Observations of stomatal conductance indicated a dominant role of vapor pressure deficit (VPD) in limiting C uptake. This was confirmed by running the simulation under reduced atmospheric drought (VPD of 1 kPa), which largely maintained GPP rates at pre-drought conditions. The importance of VPD as a dominant driver was underlined by simulations of extreme summer conditions. We found GPP to be affected more by summer temperatures and VPD as predicted for 2080 (-17%) than by reductions in summer precipitation (-9%). Because heterotrophic respiration responded less to heat (-1%) than to reductions in precipitation (-10%), net ecosystem C uptake declined strongest under hotter (-38%) compared to drier summer conditions (-8%). Considering warming trends across all seasons (September-May: +3 °C and June-August: +4.5 °C), the negative drought effects were largely compensated by an earlier initiation of favorable growing conditions and bud break, enhancing early season GPP and needle biomass. An adverse effect, triggered by changes in early season allocation patterns, was the decline of wood and root biomass. This imbalance may increase water stress over the long term to a threshold at which ponderosa pine may not survive, and highlights the need for an integrated process understanding of the combined effects of trends and extremes

Sibling Relationship and Behavioral Adjustment in Families of Disabled Children: Cross-Lagged Associations

Abstract Cross-lagged panel designs were used to examine longitudinal and potential (bi)directional relationships between primary caregiver reported sibling relationship quality and the behaviors of children with intellectual disability (n = 297) and their closest in age siblings. The behavioral and emotional problems of the child with intellectual disability positively predicted sibling conflict over time. When accounting for control variables, this relationship was no longer present. Sibling warmth positively predicted the prosocial behaviors of the child with intellectual disability over time. When accounting for control variables, both sibling warmth and sibling conflict positively predicted the prosocial behaviors of the child with intellectual disability over time. Future research directions and clinical implications are discussed.</jats:p

Effects of Nosema apis, N. ceranae, and coinfections on honey bee (Apis mellifera) learning and memory

Western honey bees (Apis mellifera) face an increasing number of challenges that in recent years have led to significant economic effects on apiculture, with attendant consequences for agriculture. Nosemosis is a fungal infection of honey bees caused by either Nosema apis or N. ceranae. The putative greater virulence of N. ceranae has spurred interest in understanding how it differs from N. apis. Little is known of effects of N. apis or N. ceranae on honey bee learning and memory. Following a Pavlovian model that relies on the proboscis extension reflex, we compared acquisition learning and long-term memory recall of uninfected (control) honey bees versus those inoculated with N. apis, N. ceranae, or both. We also tested whether spore intensity was associated with variation in learning and memory. Neither learning nor memory differed among treatments. There was no evidence of a relationship between spore intensity and learning, and only limited evidence of a negative effect on memory; this occurred only in the co-inoculation treatment. Our results suggest that if Nosema spp. are contributing to unusually high colony losses in recent years, the mechanism by which they may affect honey bees is probably not related to effects on learning or memory, at least as assessed by the proboscis extension reflex

Recommendations for dietary calcium intake and bone health: the role of health literacy

Osteoporosis, a common disease of the skeleton, involves microarchitecturaldeterioration of the bone matrix and depletion of bonemineral; this results in an increased susceptibility to fracture [1]. Postfracture,there is a plethora of financial, personal and psychosocialoutcomes, including reduced mobility, impairment of daily activities,inability to work and loss of confidence [2,3]. A hip fracture has themost severe implications: one in five individuals die within the firstyear, while 60% of individuals who survive a hip fracture still requireassistance to walk one year later, and 33% are totally dependent or areadmitted to a nursing home [2,4]. Bone mass is an important predictorof osteoporosis, and future fracture risk [5], and calcium plays animportant role in normal growth, development and maintenance of theskeleton [6], including providing a dynamic store to maintain theintra- and extra-cellular calcium pools [7]. Calcium homeostasis isregulated by an integrated hormonal system that involves calcitonin,parathyroid hormone (PTH) and the PTH receptor, and 1,25-dihydroxyvitamin D and the vitamin D receptor [7,8], along withserum ionized calcium, and the calcium-sensing receptor [9]. Whenplasma concentrations of ionized calcium fall below optimal levels,bone resorption increases in order to restore the mineral equilibrium

Entangled quantum tunneling of two-component Bose-Einstein condensates

We examine the quantum tunneling process in Bose condensates of two interacting species trapped in a double well configuration. We discover the condition under which particles of different species can tunnel as pairs through the potential barrier between two wells in opposition directions. This novel form of tunneling is due to the interspecies interaction that eliminates the self- trapping effect. The correlated motion of tunneling atoms leads to the generation of quantum entanglement between two macroscopically coherent systems.Comment: 4 pages, 3 figure

Efficient Selfconsistent Calculations of Multiband Superconductivity in UPd2_2Al3_3

An efficient physically motivated computational approach to multiband superconductivity is introduced and applied to the study of the gap symmetry in a heavy-fermion, UPd$_2$Al$_3$. Using realistic pairing potentials and accurate energy bands that are computed within density functional theory, self-consistent calculations demonstrate that the only accessible superconducting gap with nodes exhibits d-wave symmetry in the $A_{1g}$ representation of the $D_{6h}$ point group. Our results suggest that in a superconductor with gap nodes the prevailing gap symmetry is dictated by the constraint that nodes must be as far as possible from high-density areas

Graviton Resonances in E+ E- -> MU+ MU- at Linear Colliders with Beamstrahlung and ISR Effects

Electromagnetic radiation emitted by the colliding beams is expected to play an important role at the next generation of high energy e^+ e^- linear collider(s). Focusing on the simplest process e+e- -> mu+ mu-, we show that radiative effects like initial state radiation (ISR) and beamstrahlung can lead to greatly-enhanced signals for resonant graviton modes of the Randall-Sundrum model.Comment: 20 pages Latex, 7 eps figure