Damping-Antidamping Effect on Comets Motion

We make an observation about Galilean transformation on a 1-D mass variable systems which leads us to the right way to deal with mass variable systems. Then using this observation, we study two-bodies gravitational problem where the mass of one of the bodies varies and suffers a damping-antidamping effect due to star wind during its motion. For this system, a constant of motion, a Lagrangian and a Hamiltonian are given for the radial motion, and the period of the body is studied using the constant of motion of the system. Our theoretical results are applied to Halley's comet.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:0910.468

Music to Mend Heartache: Song Choices to Match, Change, and Distract Mood

Romantic turmoil is something that most people experience in their life. When faced with an upsetting event, such as a breakup or fight with a partner, a person may turn to music to achieve a more desirable state of mind. The current study extended past research on music and coping by focusing specifically on a person’s use of music when they have emotional distress due to a romantic event. Ten interviews revealed the major theme “Music as a Tool,” regarding how people use music as social support. The first subtheme, Alliance with Mood, describes how participants used music as a tool to relate/identify and experience their current emotions. The second subtheme, Changing Mood, reveals how participants used music as tool to reframe their emotions and distract themselves. Because of the practical nature of this subject, media studies should continue to advance the literature on music and social support

A multiscale hybrid mathematical model of epidermal-dermal interactions during skin wound healing.

Following injury, skin activates a complex wound healing programme. While cellular and signalling mechanisms of wound repair have been extensively studied, the principles of epidermal-dermal interactions and their effects on wound healing outcomes are only partially understood. To gain new insight into the effects of epidermal-dermal interactions, we developed a multiscale, hybrid mathematical model of skin wound healing. The model takes into consideration interactions between epidermis and dermis across the basement membrane via diffusible signals, defined as activator and inhibitor. Simulations revealed that epidermal-dermal interactions are critical for proper extracellular matrix deposition in the dermis, suggesting these signals may influence how wound scars form. Our model makes several theoretical predictions. First, basal levels of epidermal activator and inhibitor help to maintain dermis in a steady state, whereas their absence results in a raised, scar-like dermal phenotype. Second, wound-triggered increase in activator and inhibitor production by basal epidermal cells, coupled with fast re-epithelialization kinetics, reduces dermal scar size. Third, high-density fibrin clot leads to a raised, hypertrophic scar phenotype, whereas low-density fibrin clot leads to a hypotrophic phenotype. Fourth, shallow wounds, compared to deep wounds, result in overall reduced scarring. Taken together, our model predicts the important role of signalling across dermal-epidermal interface and the effect of fibrin clot density and wound geometry on scar formation. This hybrid modelling approach may be also applicable to other complex tissue systems, enabling the simulation of dynamic processes, otherwise computationally prohibitive with fully discrete models due to a large number of variables

Carbon dioxide (CO2) and methane (CH4) fluxes from agricultural drainage canals at the Timberlake Observatory for Wetland Restoration in North Carolina’s coastal plain

Wetlands play an integral role in the global biogeochemical cycling of carbon (C). Historically, research on carbon dynamics in wetlands has focused on large-scale wetlands that are easily recognized on the landscape. However, cryptic wetlands- wetlands that may be small-scale, seasonally inundated, and/or otherwise difficult to identify or characterize on a landscape- occur throughout the Earth’s surface. Agricultural drainage canals represent one type of cryptic wetland environment. Even though they are individually small, the collective imprint of drainage canals across a landscape, especially in low-lying regions where land use is dominated by agriculture, may be large. Herein, we measure CO2 and CH4 emissions from agricultural drainage canals at the Timberlake Observatory for Wetland Restoration in Tyrrell County, North Carolina. Our findings indicate that the inclusion of agricultural drainage canals in the measured GHG fluxes from Timberlake increases site CO2 and CH4 emissions by ca. 1% each. Therefore, agricultural drainage canals may be an unrecognized source of C-fluxes in low-lying regions of the Earth dominated by cropland

Carbon dioxide (CO2) and methane (CH4) fluxes from agricultural drainage canals at the Timberlake Observatory for Wetland Restoration in North Carolina’s coastal plain

Wetlands play an integral role in the global biogeochemical cycling of carbon (C). Historically, research on carbon dynamics in wetlands has focused on large-scale wetlands that are easily recognized on the landscape. However, cryptic wetlands- wetlands that may be small-scale, seasonally inundated, and/or otherwise difficult to identify or characterize on a landscape- occur throughout the Earth’s surface. Agricultural drainage canals represent one type of cryptic wetland environment. Even though they are individually small, the collective imprint of drainage canals across a landscape, especially in low-lying regions where land use is dominated by agriculture, may be large. Herein, we measure CO2 and CH4 emissions from agricultural drainage canals at the Timberlake Observatory for Wetland Restoration in Tyrrell County, North Carolina. Our findings indicate that the inclusion of agricultural drainage canals in the measured GHG fluxes from Timberlake increases site CO2 and CH4 emissions by ca. 1% each. Therefore, agricultural drainage canals may be an unrecognized source of C-fluxes in low-lying regions of the Earth dominated by cropland

Splash control of drop impacts with geometric targets

Drop impacts on solid and liquid surfaces exhibit complex dynamics due to the competition of inertial, viscous, and capillary forces. After impact, a liquid lamella develops and expands radially, and under certain conditions, the outer rim breaks up into an irregular arrangement of filaments and secondary droplets. We show experimentally that the lamella expansion and subsequent break up of the outer rim can be controlled by length scales that are of comparable dimension to the impacting drop diameter. Under identical impact parameters, ie. fluid properties and impact velocity, we observe unique splashing dynamics by varying the target cross-sectional geometry. These behaviors include: (i) geometrically-shaped lamellae and (ii) a transition in splashing stability, from regular to irregular splashing. We propose that regular splashes are controlled by the azimuthal perturbations imposed by the target cross-sectional geometry and that irregular splashes are governed by the fastest-growing unstable Plateau-Rayleigh mode

INFLUÊNCIA DO DIÂMETRO DE ESTACAS NO DESENVOLVIMENTO DOS BROTOS DE Platanus x acerifolia

O objetivo do presente trabalho foi determinar o diâmetro ideal de estacas para a produção de mudas de Platanus x acerifolia. As estacas utilizadas foram coletadas em árvores cuja a brotação apresentava-se com um ano de idade. Foram comparados três diâmetros de estacas: diâmetros inferiores a 1 cm, diâmetros entre 1 e 2 cm e diâmetros superiores a 2 cm. Todas as estacas possuiam 30 cm de comprimento. Decorridos 90 dias do plantio das estacas, foram medidas as alturas dos brotos, onde na qual o maior desenvolvimento foi observado nas estacas com diâmetro entre 1 e 2 centímetros