2,638 research outputs found
A new species of Ribautiella (Myriapoda, Symphyla, Scolopendrellidae) from an Amazonian black-water inundation forest and notes on its natural history and ecology
Ribautiella amazonica is described from a black-water inundation forest near Manaus, Brazil. The genus is recorded for the first time for the Americas. R. amazonica was predominantly collected from the forest soil, mainly between 7 and 14 cm depth and is considered euedaphic. Data indicate, that advanced immature stages and adults withstand forest-inundation of 5 - 6 months duration in the soil and reproduce in the early part of the emersion period
Бандаж робочого колеса турбінного ступеня
Бандаж робочого колеса турбінного ступеня містить бандажну стрічку з отворами, що відповідають формі шипів робочих лопаток, просунутих в отвори бандажної стрічки, та допоміжне кільце з ущільнювальними гребенями на його зовнішній поверхні, яке надіте на бандажну стрічку. На зовнішній торцевій частині шипів робочих лопаток виконані виступи циліндричної, сферичної або конічної форми. На внутрішній частині допоміжного кільця з ущільнювальними гребенями створені лунки, розміри яких відповідають формі і розмірам зазначених виступів над шипами робочих лопаток
Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot
We report a thermally activated metastability in a GaAs double quantum dot
exhibiting real-time charge switching in diamond shaped regions of the charge
stability diagram. Accidental charge traps and sensor back action are excluded
as the origin of the switching. We present an extension of the canonical double
dot theory based on an intrinsic, thermal electron exchange process through the
reservoirs, giving excellent agreement with the experiment. The electron spin
is randomized by the exchange process, thus facilitating fast, gate-controlled
spin initialization. At the same time, this process sets an intrinsic upper
limit to the spin relaxation time.Comment: 4 pages, 5 figures (color
Bone marrow adipose tissue is a unique adipose subtype with distinct roles in glucose homeostasis
PROBLEMS IN THE DETERMINATION OF EFFECTIVE DIFFUSION COEFFICIENTS OF GASES AND LIQUIDS USING THE UP-TAKE TECHNIQUE
Diffusion processes play an important role in many areas of science and technology. Since pore diffusion processes strongly depend on the pore texture of the porous solid, a desired value of an effective diffusion coefficient, D, has to be determined experimentally. Although, several measuring techniques have been described in the open literature, only a few of them can be used to set up a routine procedure. One of these methods is the so-called Up-Take Technique. The evaluation of the experimental data in this case, however, can lead to difficulties which will be discussed in detail
How well can people observe the flow state of temporary streams?
Even though more than half of the global river network does not have continuous flow, temporary (i.e., non-perennial) streams are poorly represented in traditional monitoring networks. Therefore, new approaches are needed to monitor these streams. Citizen science provides an interesting opportunity as people, equipped with smartphones, can observe the flow state of temporary streams. Such observations can go beyond a simple classification of flow vs. no flow and include ecologically important states, such as standing water, isolated pools, or wet streambeds. However, the quality of citizen science data for temporary streams has so far not been thoroughly assessed. Therefore, we asked more than 1,200 people during 23 field days to visually determine the flow state of eight temporary streams based on six classes ranging from a dry streambed to flowing water. Participants could most clearly distinguish a flowing stream from a non-flowing stream. The overall agreement between participants was 66%; 83% of the selected flow states were within one class of the most frequently selected flow state. The agreement with the expert was lower (56% chose the same class, and 79% chose a state within one class). Inconsistencies between the selected flow state and answers to specific yes-no statements about the temporary stream were largest for the dry streambed and damp/wet streambed states. These discrepancies were partly caused by participants looking at different parts of the stream (i.e., participants considered the flow state for a location further upstream or downstream). To ensure that all participants determine the flow state comparably, we recommend clear definitions of the flow state classes, detailed information on the exact location for which the flow state needs to be determined, as well as more training
Optimal control of serial, multi-echelon inventory/production systems with periodic batching
We consider a single-item, periodic-review, serial, multi-echelon inventory system, with linear inventory holding and penalty costs. In order to facilitate shipment consolidation and capacity planning, we assume the system has implemented periodic batching: each stage is allowed to order at given equidistant times. Further, for each stage except the most downstream one, the reorder interval is assumed to be an integer multiple of the reorder interval of the next downstream stage. This reflects the fact that the further upstream in a supply chain, the higher setup times and costs tend to be, and thus stronger batching is desired. Our model with periodic batching is a direct generalization of the serial, multi-echelon model of Clark and Scarf (1960). For this generalized model, we prove the optimality of basestock policies, we derive Newsboy-type characterizations for the optimal basestock levels, and we describe an efficient exact solution procedure for the case with mixed Erlang demands. Finally, we present extensions to assembly systems and to systems with a modified fill rate constraint instead of backorder costs. Subject classification: Inventory/Production: Multi-echelon, stochastic demand, periodic batching, optimal policies.
Effectiveness of Forest Management Strategies to Mitigate Effects of Global Change in South-Central Siberia
We investigated questions about the ability of broad silvicultural strategies to achieve multiple objectives (reduce disturbance losses, maintain the abundance of preferred species, mitigate fragmentation and loss of age-class diversity, and sequester aboveground carbon) under future climate conditions in Siberia. We conducted a factorial experiment using the LANDIS-II landscape disturbance and succession model. Treatments included varying the size and amount of areas cut and the cutting method (selective or clearcut). Simultaneously, the model simulated natural disturbances (fire, wind, insect out-breaks) and forest succession under projected future climate conditions as predicted by an ensemble of global circulation models. The cutting method and cutting rate treatments generally had a large effect on species and age-class composition, residual living biomass, and susceptibility to disturbance, whereas cutblock size had no effect. Cutblock size affected only measures of fragmentation, but cutting method and cutting rate often had an even greater effect. Based on the results, we simulated a “recommended” strategy and compared it with the current forest management practice. The recommended strat-egy resulted in greater forest biomass, increased abundance of favored species, and reduced fragmentation, but it did not sig-nificantly reduce losses by disturbance. No single strategy appears able to achieve all possible forest management objectives
GaAs Quantum Dot Thermometry Using Direct Transport and Charge Sensing
We present measurements of the electron temperature using gate defined
quantum dots formed in a GaAs 2D electron gas in both direct transport and
charge sensing mode. Decent agreement with the refrigerator temperature was
observed over a broad range of temperatures down to 10 mK. Upon cooling nuclear
demagnetization stages integrated into the sample wires below 1 mK, the device
electron temperature saturates, remaining close to 10 mK. The extreme
sensitivity of the thermometer to its environment as well as electronic noise
complicates temperature measurements but could potentially provide further
insight into the device characteristics. We discuss thermal coupling
mechanisms, address possible reasons for the temperature saturation and
delineate the prospects of further reducing the device electron temperature.Comment: 8 pages, 3 (color) figure
Forest Restoration in a Mixed-Ownership Landscape under Climate Change
The article presents a study regarding forest management associated with climate change. It mentions that preservation endeavors and restoration schemes should diminish current threats like unsuited forest management and development while integrating possible effects of climate change. It also stresses that an adaptive approach to management can be the most efficient strategy of forest restoration given the doubts of climate change impacts
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