ALBERT

Description: Presents the findings of a multiyear study of the effectiveness of reform-oriented science and mathematics teaching (instructional practices for engaging students actively in their own learning and enhancing the development of complex cognitive skills)-specifically, whether such practices are associated with higher student achievement and whether that association is sensitive to the aspects of achievement that are measured. (CD-ROM enclosed.)

Description: In 2000, Edison Schools, the nation's largest education management organization, asked RAND to analyze its achievement outcomes and design implementation. RAND evaluated Edison's strategies for promoting student achievement in its schools, how it implemented those strategies, how its management affected student achievement, and what factors explained differences in achievement trends among its schools.

Description: The West Philippine Basin (WPB) is a back-arc basin that opened within the Philippine Sea Plate (PSP) between the current position of the Palau-Kyushu Ridge (PKR) and the margin of East Asia. Spreading occurred at the Central Basin Fault (CBF) mainly from 54 until 30 Ma. The PKR was active since ~ 48 to 35 Ma constituting a single volcanic arc with the Izu-Bonin-Mariana (IBM) Arc. At ~ 42 Ma ago spreading rate and direction changed from NE-SW to NS, stopping at ~ 30 Ma. A late phase of spreading and volcanism took place between 30 and 26 Ma. ODP Leg 195 Site 1201 is located in the WPB, ~ 100 km west of the PKR, on 49 Ma crust formed by NE-SW spreading at the CBF. From ~ 35 to 30 Ma, pelagic sedimentation at Site 1201 was followed by turbidite sedimentation, fed mostly by arc-derived volcanic clasts. The geochemical and isotopic features of Site 1201 basement rocks, which represent Eocene WPB oceanic crust, compared with those of Site 1201 volcanics from the turbidite sequence, representing products of the early Mariana Arc (PKR), provide some insights into the early history of the IBM subduction factory. The WPB basement is made up of aphyric to porphyritic basalts with altered olivine, and preserved plagioclase, clinopyroxene and opaques. The PKR volcanics are porphyritic basalts and andesites with plagioclase, clino- and orthopyroxene, hornblende, alkali feldspar and opaques. Variable textures, and degree of alteration suggesting zeolite facies metamorphic grade, characterize both groups of rocks. The mineralogical and geochemical characteristics of the investigated Site 1201 PKR volcanics highlight their calc-alkaline affinity. This feature is at variance with both other PKR rocks, having mostly boninitic and arc tholeiitic affinity, and WPB basement basalt, having tholeiitic affinity, with some characters transitional to arc-like, as expected for a back-arc basin. New Sr and Nd isotope data, coupled with published Sr, Nd, Pb and Hf isotope data (Savov et al., 2006), highlight the Indian Ocean MORB-like character of Site 1201 basement basalts. This suggests that WPB volcanism tapped an upper mantle domain distinct from that underlying the Pacific Plate. The isotopic features of Site 1201 PKR volcanics are more enriched relative to those of basement basalts reflecting higher amounts of subduction-derived component(s) in the source of arc magmas. Th-Nb relationships and isotope geochemistry of the WPB basement and overlaying arc volcanics suggest addition of subducted sediment mostly as siliceous melts, to the mantle source of the arc volcanics. In that respect, Site 1201 PKR volcanics resemble calc-alkaline volcanics of the currently active Mariana Arc. In addition, the calc-alkaline affinity, unradiogenic neodymium, and inferred Middle Oligocene age of PKR volcanics, suggest they might represent an evolved stage of arc volcanism at Palau-Kyushu Ridge, perhaps shortly before the end of its activity.

Description: Published

Description: 157-171

Description: JCR Journal

Description: open

Description: Recent data indicating that the solar modulation effects are propagated outward in the heliospheric cavity suggest that the 11-year cosmic ray modulation can best be described by a dynamic time dependent model. In this context an understanding of the recovery characteristics of large transient Forbush type decreases is important. This includes the typical recovery time at a fixed energy at 1 AU as well as at large heliocentric radial distances, the energy dependence of the recovery time at 1 Au, and the dependence of the time for the intensity to decrease to the minimum in the transient decreases as a function of distance. These transient decreases are characterized by their asymmetrical decrease and recovery times, generally 1 to 2 days and 3 to 10 days respectively at approx. 1 AU. Near earth these are referred to as Forbush decreases, associated witha shock or blast wave passage. At R equal to or greater than + or - 10 AU, these transient decreases may represent the combined effects of several shock waves that have merged together.

Description: Simultaneous solar proton flux measurements on IMP 7 and by the world wide neutron monitor network during the May 7, 1978 flare event led to conclusions that in the energy range from 50 MeV to 10 GeV: (1) the propagation of the flare particles in the interplanetary magnetic field (IMF) between the Sun and the Earth was nearly scatter free; and (2) therefore, the intensity time (IT) profiles of the solar proton fluxes observed at Earth for about one hour after onset represent the solar injection profiles even to energies as low as 50 MeV. Observations of the IMF at Helios A indicate that the IMF was undisturbed between the Sun and Helios A at the time of the May 7, 1978 flare event; and, therefore, the solar particle propagation was also scatter free from the Sun to Helios A.

Description: In the morning of February 16, 1984 a solar cosmic ray event (GLE) was recorded by the world wide network of neutron monitors (NM). The counting rate vs. time profile of the Goose Bay NM (geog. lat. = 53.3 deg. N, deog. long. = 299.6 deg E) where the increase is expressed as percent of the counting rate of an equatorial sea level NM is presented. The Goose Bay NM was observed to have the maximum response to the solar particles. Its counting rate vs. time profile exhibits a rapid increase to maximum, has a large amplitude (approx. 170%) and decays rapidly to background in approx. 90 min. In Fig. 1 we also show the counting rate vs. time profile for the Tixie Bay NM (71.6 deg, 128.9 deg) which recorded an increase of only a few percent. Since the NMs at Goose Bay and Tixie Bay have asymptotic viewing directions approx. 180 deg apart in longitude, the anisotropy of the solar particle flux at Earth from these stations.

Description: Since its discovery by Forbush (1954), the 11-year cycle modulation of the cosmic ray intensity has been studied extensively. Bowe and Hatton (1982) obtained a well-behaved transfer function F between the solar activity S and the cosmic ray intensity modulation Io-I. They suggested that the 11-year variation for sunspot cycle 20 can be attributed to the modulating effect of solar flare-induced shocks propagating through the heliosphere. The cosmic ray intensity in the absence of solar activity is denoted by Io, while I denotes the observed intensity. Bowe and Hatton infer that the boundary of the heliosphere is located at a distance of 70-90 AU. Since their conclusion is of great importance in understanding the mechanism of the 11-year modulation, the present investigation is concerned with a repetition of their study for two cycles, taking into account the use of a slightly modified method. The obtained results confirm the conclusions reached by Bowe and Hatton that there is a well-behaved transfer function for solar flares.

Description: The solar flare proton rigidity spectra for several flares occurring between 1967 and 1972 have been deduced from the ground level cosmic ray neutron monitor observations. To obtain consistent agreement for all the ground level events (GLEs) analyzed, the specific yield functions of Lockwood and Webber (1967) must be reduced slightly below P = 1.6 GV. The typical spectral indices of solar cosmic rays deduced for GLEs vary from 4 to 6 if the differential spectrum is represented by KP to the minus gamma power. Only occasionally is the spectrum as steep as 8 or 9. The observed spectral index is independent of the magnitude of the integral solar proton flux above 1 GV.

Description: Neutron monitor data from the IMP 7 and 8 satellites are used in the present analysis of the cosmic ray events of Nov. 22, 1977, and May 7, 1978, in order to determine the energy spectra of the solar protons from 50 MeV to 10 GeV, together with pitch angle distributions, intensity-time profiles, and anisotropy-time profiles. The solar proton energy spectra obtained agree with the overlapping energy range when the pitch angle distribution is taken into account, and it is noted that the energy spectra covering three decades of energy and eight of intensity, together with their time variations, were very similar for the two events. The May 1978 event is important for the study of solar particle acceleration and their subsequent injection into the interplanetary medium. Although the solar proton propagation of the November 1977 event was diffusive, the solar particle injection was also time-extended and energy-dependent.

Description: Large transient decreases over 20 percent were observed above 70 MeV cosmic ray intensity in September 1991, at the three spacecraft, V1, V2, and P10, in the outer heliosphere between 35 and 53 AU. These decreases appear to be related to the intense solar activity occurring in late May and early June, which was responsible for a series of rapid transient decreases at the earth that probably reduced the over 70-MeV intensity by more than 50 percent to the 1owest level ever recorded. Average transit speeds of about 600 to 800 km/s are deduced for the propagation of these transients between the earth and the outer heliosphere. The overall picture of the propagation of these transients is consistent with a massive, almost spherical modulating region moving outward in the heliosphere. The smooth almost exponential recovery of intensities at all three spacecraft for over 160 days after the decrease, and the large total modulation beyond P10 at the time of the decrease, suggest that the modulation boundary is well beyond 53 AU and probably beyond 100 AU.