3,436 research outputs found
Transition Metal Chemistry of Oxime-Containing Ligands, Part XIV. Iron(II) Complexes of syn-Phenyl-2-pyridylketoxime and syn-Methy 1-2-pyridylketoxime
Iron(II) complexes of the type [Fe(HL)2X2] (where HL =
syn-phenyl-2-pyridylketoxime (Hppk) or syn-methyl-2-pyridylketoxime
(Hmpk) and X = c1-, Br-, I-, Ncs- or NCse-) were synthesized
and characterized by elemental analysis, molar conductance,
molecular weight determination, X-ray powder diffraction
patterns, magnetic susceptibility, Mossbauer, reflectance and IR
spectral measurements. On the basis of these physical properties
a halo-bridged dimeric cis- octahedral structure is suggested for
the iron(II) halo complexes, whereas the remaining complexes
appear to be monomeric with a cis- octahedral structur e
Unifying Black-Scholes type formulae which involve Brownian last passage times up to a finite horizon
The authors recently discovered some interesting relations between the Black-Scholes formula and last passage times of the Brownian exponential martingales, which invites one to seek analogous results for last passage times up to a finite horizon. This is achieved in the present paper, where Yuri's formula, as originally presented in Akahori, Imamura and yano (2008), is also derived
Dynamics of broken symmetry nodal and anti-nodal excitations in Bi_{2} Sr_{2} CaCu_{2} O_{8+\delta} probed by polarized femtosecond spectroscopy
The dynamics of excitations with different symmetry is investigated in the
superconducting (SC) and normal state of the high-temperature superconductor
BiSrCaCuO (Bi2212) using optical pump-probe (Pp)
experiments with different light polarizations at different doping levels. The
observation of distinct selection rules for SC excitations, present in A and B symmetries, and for the PG excitations, present in
A and B symmetries, by the probe and absence of any
dependence on the pump beam polarization leads to the unequivocal conclusion of
the existence of a spontaneous spatial symmetry breaking in the pseudogap (PG)
state
Two Modes of Solid State Nucleation - Ferrites, Martensites and Isothermal Transformation Curves
When a crystalline solid such as iron is cooled across a structural
transition, its final microstructure depends sensitively on the cooling rate.
For instance, an adiabatic cooling across the transition results in an
equilibrium `ferrite', while a rapid cooling gives rise to a metastable twinned
`martensite'. There exists no theoretical framework to understand the dynamics
and conditions under which both these microstructures obtain. Existing theories
of martensite dynamics describe this transformation in terms of elastic strain,
without any explanation for the occurence of the ferrite. Here we provide
evidence for the crucial role played by non-elastic variables, {\it viz.},
dynamically generated interfacial defects. A molecular dynamics (MD) simulation
of a model 2-dimensional (2d) solid-state transformation reveals two distinct
modes of nucleation depending on the temperature of quench. At high
temperatures, defects generated at the nucleation front relax quickly giving
rise to an isotropically growing `ferrite'. At low temperatures, the defects
relax extremely slowly, forcing a coordinated motion of atoms along specific
directions. This results in a twinned critical nucleus which grows rapidly at
speeds comparable to that of sound. Based on our MD results, we propose a
solid-state nucleation theory involving the elastic strain and non-elastic
defects, which successfully describes the transformation to both a ferrite and
a martensite. Our work provides useful insights on how to formulate a general
dynamics of solid state transformations.Comment: 3 pages, 4 B/W + 2 color figure
Mitogen-activated protein kinase (MAPK) blockade of bovine preimplantation embryogenesis requires inhibition of both p38 and extracellular signal-regulated kinase (ERK) pathways.
Blastocyst formation, as a critical period during development, is an effective indicator of embryonic health and reproductive efficiency. Out of a number of mechanisms underlying blastocyst formation, highly conserved mitogen-activated protein kinase (MAPK) signaling has emerged as a major mechanism involved in regulating murine preimplantation embryo development. The objective of our study was to ascertain the role of MAPK signaling in regulating bovine development to the blastocyst stage. Using reverse transcriptase PCR and immunohistochemical staining procedures we have demonstrated that mRNA transcripts and polypeptides encoding p38 MAPK pathway constituents are detectable in preimplantation bovine embryos from the one-cell to the blastocyst stage. Further, the effects on bovine embryo development following inhibition of p38 alpha/beta and extracellular signal-regulated kinase (ERK) signaling by treatment with SB220025 and U0126, respectively, were investigated. Eight-cell bovine embryos (50 per group; three replicates) were placed into treatments consisting of synthetic oviductal fluid (SOF) medium: SOF + SB202474 (inactive analogue), SOF + SB220025, SOF + U0124 (inactive analogue), SOF + U0126, and SOF + SB220025 + U0126. Inhibition of p38 MAPK or ERK signaling individually did not affect development to the blastocyst stage. However, when both pathways were blocked simultaneously there was a significant reduction (P \u3c 0.05) in blastocyst formation, cell number and immunofluorescence of phosphorylated downstream pathway constituents. We have determined that, in variance to what was observed during murine preimplantation development, bovine early embryos progress at normal frequencies to the blastocyst stage in the presence of p38 MAPK inhibitors
Bovine oocytes and early embryos express Staufen and ELAVL RNA-binding proteins.
RNA-binding proteins (RBP) influence RNA editing, localization, stability and translation and may contribute to oocyte developmental competence by regulating the stability and turnover of oogenetic mRNAs. The expression of Staufen 1 and 2 and ELAVL1, ELAVL2 RNA-binding proteins during cow early development was characterized. Cumulus-oocyte complexes were collected from slaughterhouse ovaries, matured, inseminated and subjected to embryo culture in vitro. Oocyte or preimplantation embryo pools were processed for RT-PCR and whole-mount immunofluorescence analysis of mRNA expression and protein distribution. STAU1 and STAU2 and ELAVL1 mRNAs and proteins were detected throughout cow preimplantation development from the germinal vesicle (GV) oocyte to the blastocyst stage. ELAVL2 mRNAs were detectable from the GV to the morula stage, whereas ELAVL2 protein was in all stages examined and localized to both cytoplasm and nuclei. The findings provide a foundation for investigating the role of RBPs during mammalian oocyte maturation and early embryogenesis
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Using Theory to Develop Healthy Choices in Motion, a Comprehensive, Experiential Physical Activity Curriculum.
Background: Research has shown that engaging in regular physical activity supports physiologic, metabolic, and immunologic processes, as well as quality of life. However, few youth in the United States meet the U.S. Department of Health and Human Services recommendation of 60 min of moderate-to-vigorous physical activity every day. School-based programs can be an effective avenue for engaging youth in physical activity, particularly when the design of the health education is based on theory, research, and practice. The purpose of this study was to design, implement, and evaluate a theory-driven physical activity curriculum for the Shaping Healthy Choices Program (SHCP) using a systematic approach. Methods: The experiential, inquiry-based physical activity curriculum, Healthy Choices in Motion (HCIM), was developed with an optional technology enhancement using Backward Design. A questionnaire to assess the curriculum's effect on physical activity knowledge was developed and assessed for content validity, internal consistency (α = 0.84), and test-retest reliability (r = 0.73). The curriculum was piloted in two phases among upper elementary-aged youth: to ensure the learning goals were met (Pilot I) and to determine the curriculum's impact on physical activity knowledge, behavior, and self-efficacy (Pilot II). Pilot II was implemented among eight 4th and 5th-grade classrooms participating in the UC CalFresh Nutrition Education Program: (1) Comparison (no intervention) (n = 25); (2) SHCP only (n = 22); (3) SHCP + HCIM (n = 42); (4) SHCP + HCIM with technology enhancement (n = 47). Analyses included unadjusted ANOVA and Bonferroni for multiple comparisons and paired t-test (p < 0.05). Results: Through the use of a methodical design approach, a comprehensive physical activity curriculum, called HCIM, was developed. Youth participating in HCIM improved physical activity knowledge compared to youth receiving no intervention (+2.8 points, p = 0.009) and youth only in the SHCP (+3.0 points, p = 0.007). Youth participating in HCIM with technology enhancement demonstrated improvements compared to youth only in the SHCP (+2.3 points, p = 0.05). Conclusion: Improvements in physical activity knowledge in youth participating in HCIM may contribute to improvements in physical activity and should be further explored in conjunction with behavioral measurements
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