333 research outputs found
Two-step rocket engine bipropellant valve Patent
Solenoid two-step valve for bipropellant flow rate control to rocket engin
Two-step rocket engine bipropellant valve concept
Initiating combustion of altitude control rocket engines in a precombustion chamber of ductile material reduces high pressure surges generated by hypergolic propellants. Two-step bipropellant valve concepts control initial propellant flow into precombustion chamber and subsequent full flow into main chamber
Coupling of organic and inorganic aerosol systems and the effect on gas-particle partitioning in the southeastern US
Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (ratio of ammonium to 2 × sulfate, R_(N∕2S) ≈ 0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NH_x) in the particle. Southeastern Aerosol Research and Characterization Network (SEARCH) gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for AeRosols and Gases in Ambient air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to a factor of 3 overestimate of the nonvolatile cations. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and aerosol mass spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H^+]_(air) (H^+ in µg m^(−3) air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid–liquid phase separation. In addition, accounting for nonideal mixing modified the pH such that a fully interactive inorganic–organic system had a pH roughly 0.7 units higher than predicted using traditional methods (pH = 1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C ≥ 0.6) compounds including several isoprene-derived tracers as well as levoglucosan but decrease particle-phase partitioning for low O : C, monoterpene-derived species
Understanding variation in salamander ionomes: A nutrient balance approach
Ecological stoichiometry uses information on a few key biological elements (C, N, and P) to
explain complex ecological patterns. Although factors driving variation in these elements are
well-established, expanding stoichiometric principles to explore dynamics of the many other
essential elements comprising biological tissues (i.e., the ionome) is needed to determine their
metabolic relationships and better understand biological control of elemental flows through
ecosystems.
2. In this paper, we report observations of ionomic variation in two species of salamander
(Ambystoma opacum and A. talpoideum) across ontogenic stages using specimens from
biological collections of two wetlands sampled over a 30-year period. This unique data set
allowed us to explore the extent of ionomic variation between species, among ontogenic stages,
between sites, and through time.
3. We found species- and to a lesser extent site-specific differences in C, N, and P along with 13
other elements forming salamander ionomes but saw no evidence of temporal changes.
Salamander ionomic composition was most strongly related to ontogeny with relatively higher
concentrations of many elements in adult males (i.e., Ca, P, S, Mg, Zn, and Cu) compared to
metamorphic juveniles, which had greater amounts of C, Fe, and Mn.
4. In addition to patterns of individual elements, covariance among elements was used to
construct multi-elemental nutrient balances, which revealed differences in salamander elemental
composition between species and sites and changes in elemental proportions across ontogenic
development. These multi-elemental balances distinguished among species-site-ontogenic stage
groups better than using only C, N, and P.
5. Overall, this study highlights the responsiveness of consumer ionomes to life-history and
environmental variation while reflecting underlying relationships among elements tied to
biological function. As such, ionomic studies can provide important insights into factors shaping
consumer elemental composition and for predicting how these changes might affect higher-order
ecological processes
Стойкость: когнитивный и психосоциальный феномены
Original manuscript received October 31, 2020. Revised manuscript accepted November 15, 2020. First published online February 08, 2021.Resilient individuals may be identified as those who are firmly grounded in today, who have benefited from yesterday, and who have the capacity of seeing themselves in tomorrow. Therefore, it is important to understand the underlying dynamics that allow these people to be resilient. The nature-nurture concept contributes to an individual’s resilience. Via neuroscience research it is becoming abundantly clear that nature is the stronger factor. The contribution of nurture, however, must also be considered. What does nurture contribute
to the individual and/or the environment? Does proper caretaking of the individual and the environment increase resilience, or does resilience merely depend upon the neuroscience of genetics? This article will explore the multifaceted concept of resilience.Стойкий индивид — это тот, кто крепко стоит на ногах сегодня, использует то, что было вчера, и способен представить себя в завтрашнем дне. Поэтому необходимо определить факторы, которые позволяют людям быть стойкими. Для понимания стойкости индивида важна концепция взаимосвязи наследственности и воспитания. Исследования в области нейронаук доказывают большую роль наследственности, но нельзя не учитывать и вклад воспитания. Каков вклад воспитания в индивида и/или его окружение? Усиливают ли устойчивость хороший уход и благоприятная среда или она зависит только от нейрогенетики? В статье обсуждается многоаспектность понятия «устойчивость»
Anyonic behavior of quantum group gases
We first introduce and discuss the formalism of -bosons and fermions
and consider the simplest Hamiltonian involving these operators. We then
calculate the grand partition function for these models and study the high
temperature (low density) case of the corresponding gases for . We show
that quantum group gases exhibit anyonic behavior in and spatial
dimensions. In particular, for a boson gas at the parameter
interpolates within a wider range of attractive and repulsive systems than the
anyon statistical parameter.Comment: LaTeX file, 19 pages, two figures ,uses epsf.st
Why Sin?—A Test and an Exploration of the Social and Psychological Context of Resentment and Desire
Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector
The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
Coupling of organic and inorganic aerosol systems and the effect on gas-particle partitioning in the southeastern US
Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (ratio of ammonium to 2 × sulfate, R_(N∕2S) ≈ 0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NH_x) in the particle. Southeastern Aerosol Research and Characterization Network (SEARCH) gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for AeRosols and Gases in Ambient air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to a factor of 3 overestimate of the nonvolatile cations. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and aerosol mass spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H^+]_(air) (H^+ in µg m^(−3) air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid–liquid phase separation. In addition, accounting for nonideal mixing modified the pH such that a fully interactive inorganic–organic system had a pH roughly 0.7 units higher than predicted using traditional methods (pH = 1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C ≥ 0.6) compounds including several isoprene-derived tracers as well as levoglucosan but decrease particle-phase partitioning for low O : C, monoterpene-derived species
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