319 research outputs found
On the existence of traveling waves in the 3D Boussinesq system
We extend earlier work on traveling waves in premixed flames in a
gravitationally stratified medium, subject to the Boussinesq approximation. For
three-dimensional channels not aligned with the gravity direction and under the
Dirichlet boundary conditions in the fluid velocity, it is shown that a
non-planar traveling wave, corresponding to a non-zero reaction, exists, under
an explicit condition relating the geometry of the crossection of the channel
to the magnitude of the Prandtl and Rayleigh numbers, or when the advection
term in the flow equations is neglected.Comment: 15 pages, to appear in Communications in Mathematical Physic
Ocena zdrowia kobiet w okresie okołomenopauzalnym
Wstęp. Okres okołomenopauzalny występuje w życiu kobiety pomiędzy okresem reprodukcyjnym, a początkiem okresu starzenia się. Zmiany hormonalne zachodzące w organizmie kobiety w okresie okołomenopauzalnym prowadzą do wystąpienia objawów zespołu klimakterycznego. Objawy mogą utrzymywać się przez klika lat wywierając wpływ na jakość życia kobiety. Cel pracy. Celem pracy była ocena zdrowia kobiet w okresie okołomenopauzalnym. Materiał i metoda. Badaną grupę stanowiło 200 kobiet. Narzędziem badawczym był samodzielnie opracowany kwestionariusz ankiety do oceny charakterystyki badanej grupy oraz kwestionariusz „Zdrowie kobiet” (Women’s Health Questionnaire- WHQ). Uzyskane wyniki badań poddano analizie statystycznej.
Wnioski. Kobiety w okresie okołomenopauzalnym odczuwają wzmożone objawy naczynioruchowe i czują się nieatrakcyjne fizycznie. Dość często wskazują również na problemy ze snem, kłopoty z pamięcią i koncentracją. Natomiast nie odczuwają raczej nastroju depresyjnego i nie mają poczucia niepokoju i lęku. Wiek, miejsce zamieszkania, wykształcenie i stan cywilny warunkują poszczególne aspekty zdrowia w grupie badanych kobiet.Introduction. Perimenopause occurs in a woman's life between the reproductive period and the onset of aging. Hormonal changes occurring in a woman’s body in the perimenopausal lead to symptoms of the climacteric syndrome. Symptoms can persist for several years, affecting the quality of life of a woman. Aim of the study. The aim of the study was to assess the health of women in the perimenopausal period. Materials and method. The study group consisted of 200 women. The research tools were: a self-developed questionnaire survey to assess the characteristics of the study group and "Women's Health Questionnaire” (WHQ). The results obtained were analysed statistically. Conclusions. In the perimenopausal period, women experience increased vasomotor symptoms and feel physically unattractive. Quite often they also indicate problems with sleep, memory, and concentration. On the other hand, they are not depressed and do not feel anxiety or anxiety. Age, place of residence, education and marital status are the determinants of the health aspects of the study group
Effect of soil saturation on denitrification in a grassland soil
Nitrous oxide (N2O) is of major importance as a greenhouse gas and precursor of ozone (O3) destruction in the stratosphere mostly produced in soils. The soil-emitted N2O is generally predominantly derived from denitrification and, to a smaller extent, nitrification, both processes controlled by environmental factors and their interactions, and are influenced by agricultural management. Soil water content expressed as water-filled pore space (WFPS) is a major controlling factor of emissions and its interaction with compaction, has not been studied at the micropore scale. A laboratory incubation was carried out at different saturation levels for a grassland soil and emissions of N2O and N2 were measured as well as the isotopocules of N2O. We found that flux variability was larger in the less saturated soils probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. The results agreed with denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71% WFSP). The isotopocules data indicated isotopic similarities in the wettest treatments vs. the two drier ones. The results agreed with previous findings where it is clear there are two N pools with different dynamics: added N producing intense denitrification vs. soil N resulting in less isotopic fractionation
On the variational limits of lattice energies on prestrained elastic bodies
We study the asymptotic behaviour of the discrete elastic energies in
presence of the prestrain metric , assigned on the continuum reference
configuration . When the mesh size of the discrete lattice in
goes to zero, we obtain the variational bounds on the limiting (in the sense of
-limit) energy. In case of the nearest-neighbour and
next-to-nearest-neibghour interactions, we derive a precise asymptotic formula,
and compare it with the non-Euclidean model energy relative to
Why place matters in residential care: the mediating role of place attachment in the relation between adolescents’ rights and psychological well-being
Little evidence exists on the relationship between rights’ perceptions and well-being outcomes during the adolescence, and particularly in care, as well as on the mediating role of place attachment. Young people in residential care are psychologically and socially vulnerable, showing greater difficulties than their peers do in the family. Youth’s rights fulfilment in residential care may positively affect their psychological functioning together with positive attachments to this place. A sample of 365 adolescents in residential care settings (M = 14.71, SD = 1.81) completed a set of self-reported measures, specifically, the Rights perceptions scale, the Place attachment scale and Scales of psychological well-being. Results revealed significant mediating effects of place attachment (Global scale and subscales of Friends Bonding and Place Dependence) on the relationship between Participation and Protection rights in residential care and Psychological well-being (Positive Relations with others, Personal Growth and Self-Acceptance). The positive role of rights fulfilment in residential care, specifically participation opportunities, as well as the role of youth’s attachment to the care setting are discussed based on previous evidence and theoretical assumptions. A set of practical implications is described.info:eu-repo/semantics/acceptedVersio
Existence and stability of viscoelastic shock profiles
We investigate existence and stability of viscoelastic shock profiles for a
class of planar models including the incompressible shear case studied by
Antman and Malek-Madani. We establish that the resulting equations fall into
the class of symmetrizable hyperbolic--parabolic systems, hence spectral
stability implies linearized and nonlinear stability with sharp rates of decay.
The new contributions are treatment of the compressible case, formulation of a
rigorous nonlinear stability theory, including verification of stability of
small-amplitude Lax shocks, and the systematic incorporation in our
investigations of numerical Evans function computations determining stability
of large-amplitude and or nonclassical type shock profiles.Comment: 43 pages, 12 figure
Early season N<sub>2</sub>O emissions under variable water management in rice systems: source-partitioning emissions using isotope ratios along a depth profile
Soil moisture strongly affects the balance between nitrification, denitrification
and N2O reduction and therefore the nitrogen (N) efficiency and N
losses in agricultural systems. In rice systems, there is a need to improve
alternative water management practices, which are designed to save water and
reduce methane emissions but may increase N2O and decrease nitrogen
use efficiency. In a field experiment with three water management treatments,
we measured N2O
isotope ratios of emitted and pore air N2O
(δ15N, δ18O and site preference, SP) over the
course of 6 weeks in the early rice growing season. Isotope ratio
measurements were coupled with simultaneous measurements of pore water
NO3-, NH4+, dissolved organic carbon (DOC), water-filled pore space (WFPS) and soil redox potential (Eh) at three soil depths.
We then used the relationship between SP × δ18O-N2O and
SP × δ15N-N2O in simple two end-member
mixing models to evaluate the contribution of nitrification, denitrification
and fungal denitrification to total N2O emissions and to estimate
N2O reduction rates. N2O emissions were higher in a
dry-seeded + alternate wetting and drying (DS-AWD) treatment relative to
water-seeded + alternate wetting and drying (WS-AWD) and
water-seeded + conventional flooding (WS-FLD) treatments. In the DS-AWD
treatment the highest emissions were associated with a high contribution from
denitrification and a decrease in N2O reduction, while in the WS
treatments, the highest emissions occurred when contributions from
denitrification/nitrifier denitrification and nitrification/fungal
denitrification were more equal. Modeled denitrification rates appeared to be
tightly linked to nitrification and NO3- availability in all
treatments; thus, water management affected the rate of denitrification and
N2O reduction by controlling the substrate availability for each
process (NO3- and N2O), likely through changes in
mineralization and nitrification rates. Our model estimates of mean
N2O reduction rates match well those observed in 15N
fertilizer labeling studies in rice systems and show promise for the use of
dual isotope ratio mixing models to estimate N2 losses.</p
Dem Stickstoff auf der Spur: N2O Prozesse und Nmin Dynamik nach Grünlanderneuerung
Eine weit verbreitete Maßnahme des Grünlandmanagements, die zur Beseitigung von Narbenschäden und zur Steigerung der Futterqualität in unproduktiven Grünländern angewendet wird, ist die Grünlanderneuerung. Die mechanische Bearbeitung von Grünlandböden und die dadurch gesteigerte Mineralisation durch den Abbau organischer Bodensubstanz und der alten Grasnarbe kann zu hohen N-Verlusten in Form des klimarelevanten Treibhausgases Lachgas (N2O) und/oder Nitratauswaschung (NO3-) führen. Bisher gibt es jedoch über die Dauer des beschriebenen Effektes, sowie den Einfluss unterschiedlicher Grünlanderneuerungstechniken nur wenige Informationen. Insbesondere für die nationale Treibhausgasbilanzierung ist es jedoch von Bedeutung, die Prozesse der N2O Umsetzung und ihre Quellen zu kennen und zu erfassen, da sich nur so Maßnahmen zur Emissionsminderung ableiten lassen. Zu diesem Zweck wurde ein Parzellenversuch (2013-2015) auf zwei Standorten (Plaggenesch, Anmoorgley) in der Nähe von Oldenburg (Niedersachsen) mit unterschiedlichen Erneuerungsvarianten etabliert. Als Referenzvarianten dienten: Grünlandumwandlung in Ackerland (Mais) und langjähriges Dauergrünland. Die N2O Flüsse und die Dynamik des mineralischen N (Nmin) wurden über einen Zeitraum von zwei Jahren untersucht. Zusätzlich wurden Nmin Profile (0-90 cm) genutzt, um den N-Verlust über Winter zu quantifizieren und das Risiko einer möglichen NO3- Auswaschung abzuschätzen. Obwohl die N2O Flüsse für einen kurzen Zeitraum (2 Monate) nach der Bearbeitung erhöht waren, konnte kein Jahreseffekt festgestellt werden. Im ersten Winter nach dem Aufbrechen der alten Grasnarbe trat jedoch für den Plaggenesch ein erhöhtes Risiko für NO3- Auswaschung auf. Die Untersuchung der N2O-Produktionswege und der N2O-Reduktion zu N2 (dem Endprodukt der Denitrifikation) erfolgte unter Nutzung stabiler Isotope. Hierzu wurde die 15N-Gasflussmethode im Sommer 2014 angewendet (1). Zusätzlich wurden natürlich vorhandene stabile Isotopensignaturen im bodenbürtigen N2O (δ15NbulkN2O, δ18ON2O und δ15NSPN2O = intramolekulare Verteilung von 15N im N2O Molekül) genutzt, um Quellen der N2O-Bildung im ersten Jahr nach Grünlanderneuerung (2013-2014) zu ermitteln. Auf dem Anmoorgley wurden große N-Verluste durch den Prozess der Denitrifikation bestimmt, wobei N2 die Emissionen dominerte. Für den Plaggenesch konnten generell geringere gasförmige Verluste festgestellt werden
- …