University of New Hampshire

About: University of New Hampshire is a education organization based out in Durham, New Hampshire, United States. It is known for research contribution in the topics: Population & Solar wind. The organization has 9379 authors who have published 24025 publications receiving 1020112 citations. The organization is also known as: UNH.

Cluster observations of an intense normal component of the electric field at a thin reconnecting current sheet in the tail and its role in the shock-like acceleration of the ion fluid into the separatrix region

Abstract: [1] Measurements from the Cluster spacecraft of electric fields, magnetic fields, and ions are used to study the structure and dynamics of the reconnection region in the tail at distances of ∼18 RE near 22.4 MLT on 1 October 2001. This paper focuses on measurements of the large amplitude normal component of the electric field observed in the ion decoupling region near the reconnection x-line, the structure of the associated potential drops across the current sheet, and the role of the electrostatic potential structure in the ballistic acceleration of ions across the current sheet. The thinnest current sheet observed during this interval was bifurcated into a pair of current sheets and the measured width of the individual current sheet was 60–100 km (3–5 c/ωpe). Coinciding with the pair of thin current sheets is a large-amplitude (±60 mV/m) bipolar electric field structure directed normal to the current sheets toward the midplane of the plasma sheet. The potential drop between the outer boundary of the thin current sheet and the neutral sheet due to this electric field is 4–6 kV. This electric field structure produces a 4–6 kV electric potential well centered on the separatrix region. Measured H+ velocity space distributions obtained inside the current layers provide evidence that the H+ fluids from the northern and southern tail lobes are accelerated into the potential well, producing a pair of counterstreaming, monoenergetic H+ beams. These beams are directed within 20 degrees of the normal direction with energies of 4–6 keV. The data also suggest there is ballistic acceleration of O+ in a similar larger-scale potential well of 10–30 kV spatially coinciding with the larger scale size (∼1000–3000 km) portions of current sheet surrounding the thin current sheet. Distribution functions show counterstreaming O+ populations with energies of ∼20 keV accelerated along the average normal direction within this large-scale potential structure. The normal component of the electric field in the thin current sheet layer is large enough to drive an E × B drift of the electrons ∼10,000 km/s (0.25 x electron Alfven velocity), which can account for the magnitude of the cross-tail current associated with the thin current sheet.

Comprehension strategies in the development of a mental model.

Abstract: It is generally assumed that the comprehension strategy used in the development of a mental model for narrative texts focuses on information that is relevant to the protagonist. Experiments 1a and 1b confirmed that readers remain sensitive to the location of the protagonist even when strategies based on text-base level representations predict this information should not be active. Experiments 2 and 3 tested the stronger claim that readers adopt the perspective of the protagonist. Ss did not notice information that was contradictory from the perspective of the protagonist unless explicitly instructed to adopt that perspective. It was concluded that, at the level of the mental model, readers focus on information relevant to the protagonist but that they do not adopt the perspective of the protagonist unless characteristics of the text induce such a strategy. Language: en

Wisconsinan and Holocene Climate History from an Ice Core at Taylor Dome, Western Ross Embayment, Antarctica

Abstract: Geochemical data and geophysical measurements from a 554‐m ice‐core from Taylor Dome, East Antarctica, provide the basis for climate reconstruction in the western Ross Embayment through the entire ...

Updating a situation model: a memory-based text processing view.

Abstract: Previous research (J. E. Albrecht & E. J. O'Brien, 1993) demonstrated that readers were aware of an inconsistency between an earlier described characteristic of a protagonist and a subsequent target action carried out by the protagonist. In a series of 5 experiments, a qualification was added to the described characteristic that restricted the conditions under which the characteristic was operative. According to the here-and-now view of mapping, readers should use this qualification to maintain a fully updated model of the protagonist in active memory and should not experience comprehension difficulty when reading the target action. In contrast, according to the memory-based text processing view, the qualification would not be part of the active discourse model. Instead, it would be reactivated when the target action was read. Thus, readers should still experience comprehension difficulty. Results of all 5 experiments were consistent with the memory-based text processing view.