1,089 research outputs found
Measurement of Stochastic Entropy Production
Using fluorescence spectroscopy we directly measure entropy production of a
single two-level system realized experimentally as an optically driven defect
center in diamond. We exploit a recent suggestion to define entropy on the
level of a single stochastic trajectory (Seifert, Phys. Rev. Lett. {\bf 95},
040602 (2005)). Entropy production can then be split into one of the system
itself and one of the surrounding medium. We demonstrate that the total entropy
production obeys various exact relations for finite time trajectories.Comment: Phys. Rev. Lett., in pres
Co-designing a conceptual controlled environment agriculture (CEA) model inside an Australian maximum-security prison: A research framework
This research paper presents the framework for a research study that aims to define and evaluate the design requirements and the related feasibility of a controlled environment agriculture (CEA) system concept within a maximum-security prison in Australia. A co-design methodology will guide the study so that the views of a broad range of stakeholders can contribute to the conceptualization of a CEA farm system that is appropriately suited to correctional settings. The unique aspect of this research lies in the application of a bottom-up consultative process involving both prison administrators and inmates. Stakeholders will initially be asked to consider what CEA typology would be most suitable for a prison environment and then use this as a basis for developing a more extensive system design. As open-field agriculture represents a lower-cost alternative to CEA, this will also be considered to complement CEA. The co-design sessions will run in tandem with current growth trials of lettuce within the prison environment using different growing environments. The research is aimed at assisting to reduce the impacts of climate change, by growing produce locally. Growing produce within the prison walls reduces food miles and improves the nutritional quality of produce, which benefits longer-term inmate health. Growth trials that complement the co-design study are aimed at evaluating the ease of use for each of type growing environment. This research contributes significant new knowledge for the application of co-design in prisons, aimed at developing implementation guidelines for a CEA ecosystem that would supply fresh vegetables to pre-cooked inmate meals. The researcher has a unique perspective as an inmate. Outside community groups wishing to try CEA may also benefit from this study
Maternal micronutrient status and decreased growth of Zambian infants born during and after the maize price increases resulting from the southern African drought of 2001-2002.
OBJECTIVE: To investigate the effects on maternal micronutrient status and infant growth of the increased maize prices that resulted from the southern African drought of 2001-2002. DESIGN: Longitudinal cohort study. SETTING: A maternal and child health clinic in Lusaka, Zambia. SUBJECTS: Maternal and infant health and nutrition data and maternal plasma were being collected for a study of breast-feeding and postpartum health. Samples and data were analysed according to whether they were collected before (June to December 2001), during (January 2002 to April 2003) or after (May 2003 to January 2004) the period of increased maize price. Season and maternal HIV status were controlled for in analyses. RESULTS: Maize price increases were associated with decreased maternal plasma vitamin A during pregnancy (P = 0.028) and vitamin E postpartum (P = 0.042), with the lowest values among samples collected after May 2003 (vitamin A: 0.96 micromol l(-1), 95% confidence interval (CI) 0.84-1.09, n = 38; vitamin E: 30.8 micromol mmol(-1) triglycerides, 95% CI 27.2-34.8, n = 64) compared with before January 2002 (vitamin A: 1.03 micromol l(-1), 95% CI 0.93-1.12, n = 104; vitamin E: 38.9 micromol mmol(-1) triglycerides, 95% CI 34.5-43.8, n = 47). There were no significant effects of sampling date on maternal weight, haemoglobin or acute-phase proteins and only marginal effects on infant weight. Infant length at 6 and 16 weeks of age decreased progressively throughout the study (P-values for time of data collection were 0.51 at birth, 0.051 at 6 weeks and 0.026 at 16 weeks). CONCLUSIONS: The results show modest effects of the maize price increases on maternal micronutrient status. The most serious consequence of the price increases is likely to be the increased stunting among infants whose mothers experienced high maize prices while pregnant. During periods of food shortages it might be advisable to provide micronutrient supplements even to those who are less food-insecure
NASICON materials - a long neglected class of solid electrolytes
The so-called NASICON materials AT2P3O12 (A = alkaline metal, T = tetravalent transition metal) are known since the 1970s [1] and are derived from the first “Na+ super-ionic conductor”, Na3Zr2Si2PO12, of this group of materials. The aims of current investigations are on the one hand the better understanding of the ionic conduction and on the other hand the search for new materials with very high ionic conductivity.
For this purpose, new and simple synthesis methods have been developed, which deliver very homogeneous powders with reduced temperatures for the preparation of ceramics. In this way a lithium ion conductor with the composition Li1.5Al0.5Ti1.5P3O12 was manufactured. After sintering to highly dense ceramics a total conductivity of 0.7 mS/cm was achieved at room temperature [2] and therefore this material belongs to the best known solid oxidic Li+ ion conductors. NMR and impedance spectroscopy investigations [3-5] have shown that the bulk conductivity amounts to 3-5 mS/cm and that the grain boundaries determine the quality of the material.
In the case of Na+ ion conductors, the prototype Na3Zr2Si2PO12 was newly synthesized and gave a previously not achieved conductivity of 1 mS/cm [6]. The modification of the composition by substitution with scandium delivered conductivities of 0.8 mS/cm (Na3.4Sc2Si0.4P2.6O12) [7] and 4 mS/cm (Na3.4Zr1.6Sc0.4Si2PO12) [8]. The latter composition possesses one of the highest known Na+ ion conductivities of oxide ceramics and reaches the conductivity of liquid electrolytes. The mentioned compositions confirm the empirical criteria which are necessary for achieving high ionic conductivities in NASICON materials [9].
References:
[1] H. Y. P. Hong, Mater. Res. Bull. 11 (1976) 173-182; H. Y. P. Hong, J. B. Goodenough, J. A. Kafalas, Mater. Res. Bull. 11 (1976) 203-220
[2] Q. Ma, Q. Xu, C.-L. Tsai, F. Tietz, O. Guillon, J. Am. Ceram. Soc., (2016), in press
[3] V. Epp, Q. Ma, F. Tietz, M. Wilkening, Phys. Chem. Chem. Phys., 17 (2015) 32115-32121
[4] S. Breuer, D. Prutsch, V. Epp, Q. Ma, F. Preishuber-Pflügl, F. Tietz, M. Wilkening, J. Mater. Chem. A, 3 (2015) 21343-21350
[5] D. Rettenwander, A. Welzl, S. Pristat, F. Tietz, S. Taibl, G. J. Redhammer, J. Fleig, J. Chem. Mater. A, 4 (2016) 1506-1513
[6] S. Naqash, Q. Ma, Tietz, O. Guillon, in preparation
[7] M. Guin, F. Tietz, O. Guillon, in preparation
[8] Q. Ma, M. Guin, S. Naqash, C.-L. Tsai, F. Tietz, O. Guillon, in preparation
[9] M. Guin, F. Tietz, J. Power Sources, 273 (2015) 1056-106
Priming third-party social exclusion does not elicit children's inclusion of out-group members
This study investigates how culture and priming 3- to 7-year-old children (N = 186) with third-party social exclusion affects their subsequent inclusion of out-group members. Children in societies that tend to value social independence (Germany, New Zealand) and interdependence (Northern Cyprus) were randomly assigned to minimal groups. Next, they watched video stimuli depicting third-party social exclusion (exclusion condition) or neutral content (control condition). We assessed children's recognition of the social exclusion expressed in the priming videos and their understanding of the emotional consequences thereof. We furthermore assessed children's inclusion behaviour in a ball-tossing game in which participants could include an out-group agent into an in-group interplay. Children across societies detected third-party social exclusion and ascribed lower mood to excluded than non-excluded protagonists. Children from Germany and New Zealand were more likely to include the out-group agent into the in-group interaction than children from Northern Cyprus. Children's social inclusion remained unaffected by their exposure to third-party social exclusion primes. These results suggest that children from diverse societies recognize social exclusion and correctly forecast its negative emotional consequences, but raise doubt on the notion that social exclusion exposure affects subsequent social inclusion
Fatores abióticos e atividade externa de Melipona (Michmelia) mondury Smith, 1863 (Hymenoptera, Apidae) em Santa Catarina
Para a abelha sem ferrão uruçu-amarela (bugia), não se conhecem os limiares climáticos para o movimento externo. Visando obter informações sobre a influência dos fatores abióticos na atividade de voo, observou-se o movimento externo de três colônias, durante um ano. Em cada colônia, a cada hora, durante dez minutos, foram contabilizadas as abelhas que saíam sem nada ou com detritos e aquelas que entravam com pólen, resina, barro, sem carga e com o abdome dilatado (água ou néctar), desde o início das atividades até o cessar, ao longo do dia. Os limites horários de atividade verificados foram 4h54 (primavera) e 19h (primavera e verão) e 5h30 (outono) e 18h30 (outono e inverno), realizando 13 horas de atividade durante o outono/inverno e 14 horas durante a primavera/verão. A amplitude de temperatura para a atividade foi de 12 a 41ºC; para umidade relativa, de 39,5 a 100%. O recurso mais coletado foi o néctar (durante as quatro estações), seguido pelo pólen. Resina e barro foram coletados em temperaturas mais elevadas do que pólen e néctar. O movimento externo mostrou correlação negativa com a temperatura e positiva com a umidade relativa. As abelhas foram observadas saindo no escuro e também com chuva
Atomic effects in astrophysical nuclear reactions
Two models are presented for the description of the electron screening
effects that appear in laboratory nuclear reactions at astrophysical energies.
The two-electron screening energy of the first model agrees very well with the
recent LUNA experimental result for the break-up reaction , which so far defies all available theoretical models.
Moreover, multi-electron effects that enhance laboratory reactions of the CNO
cycle and other advanced nuclear burning stages, are also studied by means of
the Thomas-Fermi model, deriving analytical formulae that establish a lower and
upper limit for the associated screening energy. The results of the second
model, which show a very satisfactory compatibility with the adiabatic
approximation ones, are expected to be particularly useful in future
experiments for a more accurate determination of the CNO astrophysical factors.Comment: 14 RevTex pages + 2 ps (revised) figures. Phys.Rev.C (in production
Lattice instabilities of cubic NiTi from first principles
The phonon dispersion relation of NiTi in the simple cubic B2 structure is
computed using first-principles density-functional perturbation theory with
pseudopotentials and a plane-wave basis set. Lattice instabilities are observed
to occur across nearly the entire Brillouin zone, excluding three
interpenetrating tubes of stability along the (001) directions and small
spheres of stability centered at R. The strongest instability is that of the
doubly degenerate M5' mode. The atomic displacements of one of the eigenvectors
of this mode generate a good approximation to the observed B19' ground-state
structure.Comment: 11 pages, 3 figure
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