H-alpha features with hot onsets. II. A contrail fibril

The solar chromosphere observed in H-alpha consists mostly of narrow fibrils. The longest typically originate in network or plage and arch far over adjacent internetwork. We use data from multiple telescopes to analyze one well-observed example in a quiet area. It resulted from the earlier passage of an accelerating disturbance in which the gas was heated to high temperature as in the spicule-II phenomenon. After this passage a dark H-Halpha fibril appeared as a contrail. We use Saha-Boltzmann extinction estimation to gauge the onset and subsequent visibilities in various diagnostics and conclude that such H-alpha fibrils can indeed be contrail phenomena, not indicative of the thermodynamic and magnetic environment when they are observed but of more dynamic happenings before. They do not connect across internetwork cells but represent launch tracks of heating events and chart magnetic field during launch, not at present.Comment: Accepted for Astronomy & Astrophysic

The PDE4 inhibitor rolipram reverses object memory impairment induced by acute tryptophan depletion in the rat

The selective type IV phosphodiesterase inhibitor, rolipram, has been shown to improve long-term memory and can reverse the cholinergic deficit caused by scopolamine. However, the underlying mechanisms of action of rolipram remain obscure. The present study investigates the effect of rolipram in a serotonergic-deficit model of acute tryptophan depletion (ATD). In addition, the levels of plasma tryptophan (TRP) were compared to object recognition performance. The experiments were conducted using male Wistar rats. The time-dependent effect of ATD treatment (a gelatin-based protein mixture) on plasma TRP levels (0, 1, 3, and 6 h after injection) and object recognition task (ORT) performance (0.5, 1, 3, and 6 h after ATD treatment) was examined. The effect of rolipram (0, 0.01, 0.03, and 0.1 mg/kg, i.p.) was tested in the condition in which ATD induced a clear memory deficit. ATD significantly lowered the plasma TRP ratio (TRP/Sigma large neutral amino acid) with a maximum of 48%, approximately 1 h after administration. Furthermore, ATD impairs ORT performance when administered 3 h before testing. Rolipram (0.1 mg/kg) reversed the memory deficit induced by ATD in a dose-dependent manner. On the basis of previous studies and the ability to reverse a serotonergic deficit, we suggest that rolipram may act through elevation of cyclic adenosine monophosphate levels and subsequent increase in neurotransmitter release

The applicability of displacement ventilation for individual control of a microclimate

This paper introduces the desk displacement ventilation concept, which combines displacement ventilation with task conditioning. The experimental setup and results of full-scale steady-state and transient measurements and numerical simulations are described for a typical office configuration. Results are used to evaluate the concept with regard to the micro/macroclimate and thermal comfort. The steady-state results show that the separation between the micro- and macroclimate, which is characteristic of task conditioning, is less pronounced and may require improvement of the concept. This effect is investigated further via transient experiments. Results of the transient study show that the application of the displacement ventilation principle for task conditioning purposes is not suitable for standard office configurations. It should at least be supported by an additional system that introduces the air at higher velocity close to the occupant, of which several system types are already available today.</p

Effect of baselevel change on floodplain and fan sediment storage and ephemeral tributary channel morphology, Navarro River, California

Managed baselevel lowering in tributaries that emerge from small canyons onto forested floodplains affects floodplain and fan sediment storage and small ephemeral tributary channel morphology in the Navarro River basin, Mendocino Country, California, USA. Numerous small tributaries (drainage areas up to several square kilometres) flow through culverts under Highway 128 across the forested floodplain of the Navarro River and one of its major tributaries, the North Fork. Excavation significantly deepened and widened these small tributaries upstream and downstream of culverts under the highway following the 1997 flood (recurrence interval 12 years), that inundated both the floodplain and the highway and culvert system. The excavation lowered the local baselevel of the tributary systems within the floodplain. This field study documents the effect of the lowered baselevel on floodplain and fan sediment storage and ephemeral tributary channel morphology. Excavation created defined channels in the floodplain where no channels previously existed. Additionally, the excavation and baselevel change created steps, or knickpoints, that migrated headward and incised the upstream tributary channels. Tributary incision decreases the sediment storage potential of the fan and floodplain and reduces the residence time for storage of fine sediment. A reduction in fine sediment residence time degrades downstream habitat for anadromous fish and other aquatic organisms in the Navarro River. Large wood influences floodplain and small tributary channel morphology by forming steps and increases sediment residence time by trapping sediment in forested tributary-fan-floodplain systems. Although this field investigation is specific to the Navarro River basin, our findings linking culvert maintenance excavation to geomorphic processes may be extended to other roads on forested floodplains in the Pacific Northwest or other systems with roads on floodplains